JPH11210557A - Liquefied gas fuel supply device for engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To ensure engine startability at the time of low temperature and idling stability after start-up, and ensure controllability and responsiveness. SOLUTION: A fuel supply device is provided with a liquid phase injector 25 for injection-supplying LPG fuel stored in a cylinder 17, as liquid phase fuel to an engine 1; a gas phase injector 16 for injection-supplying LPG fuel stored in the cylinder 17, as gas phase fuel to the engine 1; a fuel temperature sensor 31 and a fuel pressure sensor 32 for detecting the state of LPG fuel supplied from the cylinder 17 to the liquid phase injector 25; and an electronic control unit(ECU) 36 for controlling the respective injectors 16, 25. The ECU 36 controls the liquid phase injector 25 to supply liquid phase fuel to the engine 1 in the case of judging the state of LPG fuel detected by the respective sensors 31, 31, to be liquid phase, and controls the gas phase injector 16 to supply gas phase fuel to the engine 1 in the case of judging the state of LPG fuel to be gas phase.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a liquefied gas fuel supply device for supplying liquefied gas fuel to an engine. More particularly, the present invention relates to a liquefied gas fuel supply device for an engine that selectively supplies a gaseous fuel and a liquid phase fuel to an engine.

[0002]

2. Description of the Related Art Conventionally, there is an engine using a liquefied gas such as liquefied petroleum gas (LPG) as a fuel. There is also a fuel supply device that supplies liquefied gas fuel to this type of engine.
As this type of fuel supply device, mainly liquid fuel,
That is, there is a type that supplies liquid-phase fuel to an engine. By supplying the liquid-phase fuel, it is possible to secure a relatively rich air-fuel mixture and increase the output of the engine.

[0003] However, if the liquid-phase fuel is always supplied, the fuel becomes excessive depending on the operation state of the engine, and an appropriate air-fuel ratio cannot be maintained, which may deteriorate exhaust emission and fuel efficiency.

On the other hand, Japanese Patent Application Laid-Open No. 63-5152 discloses means for supplying a liquid phase fuel, a gaseous fuel,
That is, there is disclosed a fuel supply control device which has means for supplying gas-phase fuel and selectively controls those means based on the operating state of the engine. Specifically, the control device detects at least one of the load and the rotation speed of the engine as elements indicating the operation state, and when each detected value is smaller than a predetermined value, that is, when the engine is at a low load or a low rotation, By supplying gas-phase fuel to the engine by gas-phase fuel supply means, an appropriate air-fuel ratio and fuel efficiency are ensured. On the other hand, when each of the detected values is larger than a predetermined value, that is, when the engine is under a high load or a high speed, the control unit supplies the liquid-phase fuel to the engine by the liquid-phase fuel supply means to thereby output the engine output. We are improving.

[0005]

However, in the conventional fuel supply control device, the liquid-phase fuel supply means and the gas-phase fuel supply means are selectively used based on the load or rotation speed of the engine. No consideration was given to the temperature state or the fuel state. For this reason, when the engine was started at an extremely low temperature, there was a possibility that a malfunction would occur. That is, when the engine is started at a very low temperature, the gas-phase fuel is supplied, but the fuel in the cylinder is not vaporized, so that the gas-phase fuel may not be obtained. For this reason, even if the control for supplying the gaseous fuel is performed, the gaseous fuel is not actually supplied to the engine, and there is a possibility that a good startability cannot be secured. In addition, there is a possibility that idling after starting is completed becomes unstable.

[0006] On the other hand, during the operation of the engine, the operation state often changes between high load and low load, and changes between high rotation and low rotation. Accordingly, in the conventional fuel supply control device, the supply switching between the gaseous fuel and the liquid fuel is frequently performed every time the load state or the rotation speed of the engine changes. For this reason, it was not easy to ensure controllability and responsiveness including the transition period of the supply switching.

The present invention has been made in view of the above circumstances, and has as its object to switch the supply of gaseous or liquid fuel to an engine based on the temperature state or fuel state of the engine to reduce the temperature. In order to secure the engine startability at the time and the idling stability after the start,
It is an object of the present invention to provide a liquefied gas fuel supply device for an engine capable of ensuring controllability and responsiveness.

[0008]

According to one aspect of the present invention, there is provided a liquid-phase fuel supply for supplying an engine with liquefied gas fuel contained in a cylinder as a liquid-phase fuel. Means, a gas-phase fuel supply means for supplying the liquefied gas fuel contained in the cylinder to the engine as a gas-phase fuel, and a state for detecting the state of the liquefied gas fuel supplied from the cylinder to the liquid-phase fuel supply means. A fuel state detecting means for controlling the liquid fuel supply means to supply the liquid fuel to the engine when the state of the detected liquefied gas fuel is a liquid phase, and detecting the detected liquefied gas fuel state; And a supply control means for controlling the gas-phase fuel supply means to supply the gas-phase fuel to the engine when is in the gas phase.

According to the above arrangement, when the state of the liquefied gas fuel supplied to the liquid-phase fuel supply means and detected by the fuel state detection means becomes a liquid phase, the supply control means controls the liquid-phase fuel supply. The means is controlled to supply liquid fuel to the engine. On the other hand, when the state of the liquefied gas fuel supplied to the liquid-phase fuel supply means and detected by the fuel state detection means becomes gas phase, the gas-phase fuel supply means is controlled by the supply control means to Is supplied to the engine.
Therefore, when the liquefied gas fuel is difficult to vaporize, the gaseous fuel is not supplied to the engine by the gaseous fuel supply means, and the liquid fuel is properly supplied to the engine by the liquid fuel supply means. Will be supplied.
On the other hand, when the liquefied gas fuel is excessively vaporized, the liquid-phase fuel supply means does not attempt to supply the liquid-phase fuel to the engine, and the gas-phase fuel supply means appropriately supplies the gas-phase fuel to the engine. Will be supplied.

According to a second aspect of the present invention, in the first aspect of the invention, the fuel state detecting means includes a temperature sensor for detecting a temperature of the liquefied gas fuel, A pressure sensor for detecting the pressure of the liquefied gas fuel, and the supply control means determines whether the state of the liquefied gas fuel is in the liquid phase based on the temperature and the pressure detected by the temperature sensor and the pressure sensor. The purpose is to determine whether or not it is a phase.

According to the above configuration, in addition to the function of the first aspect, the parameter indicating the state of the liquefied gas fuel is specifically specified based on the temperature and the pressure detected by the temperature sensor and the pressure sensor. The supply control means determines whether the liquid phase or the gas phase.

According to a third aspect of the present invention, there is provided a driving mechanism for detecting an operating state of an engine, comprising: When the operating state indicates the deceleration of the engine, the supply of the fuel by the liquid-phase fuel supply means and the gas-phase fuel supply means is shut off, and the state of the detected liquefied gas fuel shifts from the gas phase to the liquid phase. In the case, and when the detected operating state indicates a return from the engine deceleration to the normal operation, the fuel supply is switched from the gas-phase fuel supply unit to the liquid-phase fuel supply unit. And supply switching means.

According to the above configuration, in addition to the operation of the invention described in claim 1 or 2, when the operating state detected by the operating state detecting means indicates the deceleration of the engine,
Both the supply of the liquid-phase fuel and the supply of the gas-phase fuel to the engine are cut off, thereby saving fuel. On the other hand, if the detected state of the liquefied gas fuel has shifted from the gas phase to the liquid phase, and if the detected operating state indicates a return to normal operation from deceleration of the engine, The supply of the fuel is switched from the supply to the supply of the liquid fuel. Therefore, the fuel remaining in the engine is wiped out during the deceleration while the fuel supply is cut off, and then the supply is switched from the supply of the gaseous fuel to the supply of the liquid fuel. Therefore, when switching to the supply of the liquid phase fuel, the amount of fuel supplied to the engine does not become excessive.

According to a fourth aspect of the present invention, there is provided the engine according to any one of the first to third aspects, wherein the engine is supplied to the engine with the supply of fuel. Air amount adjusting means whose opening degree is controlled to adjust the amount of air to be supplied, and when the engine is started, the amount of air supplied to the engine together with the gaseous phase fuel is supplied to the engine together with the liquid phase fuel. Air amount control means for controlling the air amount adjustment means so as to be more open than during liquid phase fuel supply so as to be relatively the same as the amount of air to be supplied. That is the purpose.

According to the above construction, in addition to the function of any one of the first to third aspects of the invention, immediately after the start of the engine, the air amount adjusting means is controlled to open by the air amount control means. Thus, the amount of air supplied to the engine together with the gaseous phase fuel is adjusted to be relatively the same as the amount of air supplied to the engine together with the liquid phase fuel. Therefore, even when the amount of air supplied to the engine may be reduced by mixing with the gas-phase fuel, the shortage of the air amount is compensated.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of a liquefied gas fuel supply system for an engine according to the present invention will now be described with reference to FIGS.
This will be described in detail with reference to FIG.

FIG. 1 is a schematic configuration diagram showing a liquefied petroleum gas (LPG) engine 1 in the present embodiment and a liquefied gas fuel supply device for supplying LPG fuel to the engine 1. The engine 1 is a multi-cylinder type having a known structure, and is mounted on an automobile. This engine 1 explodes and burns fuel and air, that is, combustible air-fuel mixture, supplied through an intake passage 2 in a combustion chamber, and discharges the combusted exhaust gas through an exhaust passage 3 to drive a piston. The crankshaft 4 is rotated to obtain power. In this embodiment, as the LPG fuel, for example, a fuel containing 30% of propane and 70% of butane is employed.

A starter 5 provided in the engine 1 assists the start of the engine 1 by applying a starting force to the crankshaft 4 when the engine 1 is started. The starter 5 is driven based on the operation of an ignition switch (not shown). The starter switch 6 provided on the starter 5 outputs a starter signal ST indicating that the engine is being started only while the starter 5 is driven, that is, until the start of the engine 1 is completed.

The rotation sensor 7 provided on the crankshaft 4 detects the rotation speed of the shaft 4, that is, the engine rotation speed NE, and outputs an electric signal according to the detection result. Water temperature sensor 8 provided in engine 1
Detects the temperature (cooling water temperature) THW of the cooling water flowing inside the engine 1 and outputs an electric signal according to the detection result. This cooling water temperature THW indicates the temperature state of the engine 1.

Air cleaner 9 provided in intake passage 2
Is for purifying the air taken into the passage 2. The air flow meter 10 provided in the intake passage 2 includes:
It measures the amount of air (intake amount) Qa that flows through the passage 2 and is taken into the engine 1, and outputs an electric signal according to the measurement result.

The throttle valve 11 provided in the intake passage 2 controls the amount of air flowing through the intake passage 2, that is, the intake air amount Qa.
It is opened and closed to adjust. This valve 1
Reference numeral 1 denotes a linkless type driven by a motor 12. The accelerator pedal 13 provided in the driver's seat of the car opens and closes the throttle valve 11,
It is operated by the driver. Accelerator sensor 1
Reference numeral 4 denotes an operation amount of the accelerator pedal 13, that is, an accelerator opening ACCP, and an electric signal corresponding to the detection result is output. The accelerator pedal 13 is operated,
When the motor 12 is driven based on the detection result of the accelerator sensor 14, the throttle valve 11 is opened and closed. Then, according to the opening degree of the valve 11, the intake air amount Q
a is adjusted. The throttle valve 11 and the motor 12 correspond to an air amount adjusting means of the present invention for adjusting the amount of air supplied to the engine 1 with the supply of the LPG fuel.

A throttle sensor 15 provided for the throttle valve 11 detects an opening degree (throttle opening degree) TA of the valve 11 and outputs an electric signal according to the detection result. The sensor 15 incorporates a well-known idle switch (not shown). This idle switch is turned on when the throttle valve 11 is fully closed, and outputs an idle signal IDL indicating that. In addition, the intake passage 2
An intake air temperature sensor (not shown) provided in the air conditioner detects the temperature of the outside air taken into the intake passage 2 and outputs an electric signal corresponding to the detection result. Similarly, an intake pressure sensor (not shown) provided in the intake passage 2 detects the intake pressure in the intake passage 2 and outputs an electric signal according to the detection result. Further, an oxygen sensor (not shown) provided in the exhaust passage 3 detects the concentration of oxygen in the exhaust gas discharged from the combustion chamber to the exhaust passage 3, and outputs an electric signal according to the detection result.

In this embodiment, the starter switch 6, the rotation sensor 7, the water temperature sensor 8, the air flow meter 10, the accelerator sensor 14, the throttle sensor 15, etc., of the present invention for detecting the operating state of the engine 1 are used. It corresponds to the operating state detecting means.

A gas-phase injector 16 provided in the intake passage 2 downstream of the throttle valve 11 is for injecting the LPG fuel contained in the cylinder 17 into the intake passage 2 as gas-phase fuel. This injector 16
Is an electromagnetic injection valve, which is always closed and electrically opened. At room temperature, in the cylinder 17, non-vaporized LPG fuel (liquid-phase fuel) is stored at the bottom, and vaporized LPG fuel (gas-phase fuel) is stored at the top. The gas-phase injector 16 receives and injects gas-phase fuel stored in the upper part of the cylinder 17. For that purpose, the gas-phase pipe 18 connected to the cylinder 17 takes out the gas-phase fuel from the upper part of the cylinder 17 and guides the gas-phase fuel taken out to the pipe 18 to the gas-phase injector 11. A first solenoid valve 19 provided adjacent to the cylinder 17 and a second solenoid valve 20 provided adjacent to the gas-phase injector 16 allow or block the flow of the LPG fuel in the gas-phase pipe 18, respectively. It is for. Gas phase piping 18
The preheater 21 provided in the
This is for supplementarily heating the PG fuel in order to maintain the gas phase. The heat generated by the preheater 21 is obtained, for example, by supplying cooling water heated by the engine 1. The regulator 22 provided in the gas-phase pipe 18 is for suppressing pressure fluctuation of the gas-phase fuel. The gas-phase injector 16 and the gas-phase pipe 18 correspond to a gas-phase fuel supply unit of the present invention.

A first fuel temperature sensor 23 as a temperature sensor provided in the gas-phase pipe 18
It detects a fuel temperature (first fuel temperature) TF1 and outputs an electric signal corresponding to the detection result. Similarly, a first pressure sensor as a pressure sensor
The fuel pressure sensor 24 detects the pressure (first fuel pressure) PF1 of the LPG fuel in the pipe 18 and outputs an electric signal according to the detection result. These sensors 2
Reference numerals 3 and 24 correspond to a fuel state detecting means for detecting the state of the LPG fuel in the gas phase pipe 18.

A liquid-phase injector 25 provided in the intake passage 2 downstream of the gas-phase injector 16 is for injecting the LPG fuel contained in the cylinder 17 into the intake passage 2 in a mist form as a liquid-phase fuel. is there. The injector 25 is an electromagnetic injection valve, which is always closed and electrically opened. The liquid injector 25 receives and injects liquid fuel stored at the bottom of the cylinder 17. For that purpose, the liquid-phase pipe 26 connected to the cylinder 17 takes out the liquid-phase fuel from the bottom of the cylinder 17,
The liquid fuel thus taken out is guided to the liquid injector 25. A third solenoid valve 27 provided in the pipe 26 adjacent to the cylinder 17 and a pipe 2 adjacent to the liquid injector 25
The fourth solenoid valve 28 provided in the pipe 6
To allow or shut off the flow of the liquid phase fuel at The filter 29 provided in the liquid phase pipe 26 is for removing foreign substances in the liquid phase fuel. The pump 30 provided in the liquid pipe 29 is for pumping the liquid fuel to the liquid injector 25 under pressure. The liquid injector 25, the liquid pipe 26, and the pump 30 correspond to a liquid fuel supply unit of the present invention.

A second fuel temperature sensor 31 as a temperature sensor provided in the liquid-phase pipe 26
It detects the fuel temperature (second fuel temperature) TF2 and outputs an electric signal according to the detection result. Similarly, a second pressure sensor provided in the liquid phase pipe 26
The fuel pressure sensor 32 detects the pressure (second fuel pressure) PF2 of the LPG fuel in the pipe 26, and outputs an electric signal according to the detection result. These sensors 3
Reference numerals 1 and 32 correspond to the fuel state detecting means of the present invention for detecting the state of the LPG fuel in the liquid phase pipe 26. Also, since the state of the LPG fuel can change reflecting the temperature state of the engine 1, these sensors 3
The reference numerals 1 and 32 also correspond to temperature state detecting means for detecting the temperature state of the engine 1.

The liquid phase pipe 26 is connected to the return pipe 33 in the liquid injector 25. This return pipe 33
Is for returning all or a part of the liquid fuel fed to the liquid injector 25 through the liquid pipe 26 to the cylinder 17. That is, when the liquid-phase injector 25 is operating, the liquid-phase fuel that has been pressure-fed to the injector 25 and has not been injected passes through the injector 25 and is returned to the cylinder 17 via the return pipe 33. On the other hand, when the liquid injector 25 is not operating,
All of the liquid-phase fuel pumped to the injector 25 passes through the injector 25 and is returned to the cylinder 17 via the return pipe 33. As described above, when the liquid-phase fuel is pressure-fed to the liquid-phase injector 25, the injector 25 is cooled by the passage of the fuel. The fifth solenoid valve 34 provided in the return pipe 33 is for permitting or blocking the flow of the liquid phase fuel in the return pipe 33. The regulator 35 provided in the return pipe 33
This is for adjusting the fuel pressure in the pipe 33.

In this embodiment, an electronic control unit (ECU) 36 includes various components output from the starter switch 6, the rotation sensor 7, the water temperature sensor 8, the air flow meter 10, the accelerator sensor 14, the throttle sensor 15, and the like. Input the signal. Based on these input signals, the ECU 36 controls the injectors 16 and 25 and the fuel injectors 25 and 25 to execute fuel supply control for supplying LPG fuel to the engine 1 and throttle control for adjusting the opening of the throttle valve 11. Solenoid valves 19, 20, 27,
28, 34, the pump 30, the motor 12, and the like, respectively. In this embodiment, the ECU 36 corresponds to the supply control unit, the supply switching unit, and the air amount control unit of the present invention. The ECU 36 is a central processing unit (CP
U), a read-only memory (ROM), a random access memory (RAM), a backup RAM, and the like. The ROM stores a predetermined control program relating to the various controls described above in advance. C
The PU executes various controls according to the control program.

Next, the contents of various controls executed by the ECU 36 will be described. FIG. 2 is a flowchart showing the contents of the fuel supply control program. The ECU 36
This program is started at each injection timing corresponding to each cylinder of the engine 1.

First, a main routine for controlling the fuel injection amount will be described. When this program is started, the ECU 36 sets each of the solenoid valves 19, 20, 27, 28,
34 is opened appropriately, and the pump 30 is operated appropriately. Then, in step 101, the ECU 36
Are the second fuel temperature TF2 and the second fuel pressure P based on the signals from the second fuel temperature sensor 31 and the fuel pressure sensor 32.
The value of F2 is read.

In step 102, the ECU 36
The fuel state is calculated based on the read fuel temperature TF2 and fuel pressure PF2. The ECU 36 performs this calculation based on function data as shown in the graph of FIG.

In step 103, the ECU 36
It is determined whether or not the calculated fuel state is a liquid phase fuel. The ECU 36 makes this determination based on the function data shown by the graph in FIG. That is, when the calculation result of the fuel state corresponds to the region above the curve shown in FIG.
The ECU 36 determines the fuel state as liquid-phase fuel, and otherwise determines as gas-phase fuel. If the determination is for gaseous fuel, the ECU 36 shifts the processing to step 111. If the determination is liquid fuel, the ECU 36 proceeds to step 110.

In step 110, the ECU 36
Whether or not a gas phase injection flag XFI1 described later is on,
That is, it is determined whether or not the mode is the gas phase injection mode. If the flag XFI1 is on, the ECU 36 determines that the mode is the gas phase injection mode, and shifts the processing to step 111. If the flag XFI1 is off, the ECU 36 determines that the mode is the liquid-phase injection mode, and shifts the processing to step 104. That is, the ECU 36 determines in step 1
Even if the determination in step 03 is liquid phase fuel, step 11
If the determination at 0 is the gas phase injection mode, the gas phase injection mode is continued without shifting to the liquid phase injection mode. If the determination in step 103 is liquid fuel and the determination in step 110 is the liquid injection mode, the operation shifts to the liquid injection mode.

In step 104, the ECU 36 reads the values of the engine speed NE and the intake air amount Qa based on the signals from the rotation sensor 7 and the air flow meter 10, respectively.

In step 105, the ECU 36
Based on the read values of the engine speed NE and the intake air amount Qa, the value of the intake air amount (unit intake air amount) Ga per rotation of the crankshaft 4 is calculated.

In step 106, the ECU 36
Values of the above-mentioned engine speed NE and unit intake air amount Ga,
The value of the liquid phase injection amount TAU2 is calculated based on the various correction values. In this calculation, the ECU 36 calculates the value of the liquid phase basic injection amount TBS2 based on the function data as shown in the graph of FIG. In this function data, the liquid phase basic injection amount TBS2 is determined in advance using the engine speed NE and the unit intake air amount Ga as parameters. For example, the engine speed NE is the lowest and the unit intake air amount G
When a is the smallest, the liquid phase basic injection amount TBS2 is “a
11 ". As the engine rotational speed NE becomes higher than the above condition, the liquid phase basic injection amount T
BS2 is "a12", "a13", ... "a17"
And increase. Here, the increase in the number is the engine speed NE.
Shows the increase in the liquid phase basic injection amount TBS2 with the rise of the pressure. On the other hand, as the unit intake amount Ga becomes larger than the above condition, the liquid phase basic injection amount TBS2 becomes “b11”, “c”.
11 ",..." G11 ". Here, the alphabetical order indicates an increase in the liquid phase basic injection amount TBS2 with an increase in the unit intake air amount Ga. The value of the liquid phase basic injection amount TBS2 corresponds to the valve opening time of the liquid phase injector 25, and the length of the valve opening time is reflected in the amount of fuel injected from the injector 25. Then, the ECU 36 reflects the various correction values such as the high-temperature correction, the intake air temperature correction, and the air-fuel ratio correction on the liquid-phase basic injection amount TBS2 calculated as described above. Calculate the value of TAU2. The ECU 36
As is well known, various correction values are calculated based on detection values of a water temperature sensor 8, an intake temperature sensor (not shown), an intake pressure sensor, an oxygen sensor, and the like, but a detailed description of the correction is omitted here.

Then, in step 107, the ECU
The control unit 36 controls the liquid injector 25 based on the calculated value of the liquid injection amount TAU2 to inject the liquid fuel into the intake passage 2 in the form of a mist. After that, ECU3
6 temporarily ends the processing.

Next, a subroutine for fuel cut during deceleration will be described. If the LPG fuel is gas phase fuel, or if the gas phase injection flag XFI1 is ON (gas phase injection mode), the ECU 36 proceeds to step 103
Alternatively, the processing is shifted from step 110 to step 111
, It is determined whether or not the current condition is a fuel cut during engine deceleration. The ECU 36 makes this determination based on the value of the separately set fuel cut flag XFC. The ECU 36 controls the fuel cut flag XFC
Is set as follows.

That is, FIG. 3 shows the program contents of the fuel cut control executed at the time of engine deceleration. ECU36
Executes this routine periodically at a timing of a predetermined period.

In step 200, the ECU 36
The values of the idle signal IDL and the engine speed NE from the throttle sensor 15 and the rotation sensor 7 are read.

In step 210, the ECU 36
It is determined whether or not the throttle valve 11 is fully closed based on the idle signal IDL. Here, the idle signal I
When DL is off, since the throttle valve 11 is open and the engine 1 is in a normal operation state, the ECU 36 sets the fuel cut flag XFC to off in step 220, and performs the subsequent processing. Stop once.

On the other hand, if the idle signal IDL is ON in step 210, the throttle valve 1
1 is fully closed, the ECU 36 determines in step 21
At 5, it is determined whether or not the value of the engine speed NE is equal to or higher than a predetermined value N1. Here, if the above determination result is negative, the ECU 36 shifts the processing to step 220. On the other hand, if the above determination is affirmative, since the engine 1 is in the deceleration operation state, the ECU 36 shifts the processing to step 230.

Then, in step 230, the ECU
36 forcibly closes all the injectors 16 and 25 to execute fuel cut. Next, at step 240, the fuel cut flag XFC is set to ON, and the subsequent processing is temporarily terminated.

According to the fuel cut control described above, when the engine 1 is decelerated, all the injectors 16 and 25 are forcibly closed, and the supply of the LPG fuel to the engine 1 is cut off. At the same time, the fuel cut flag XFC is set to ON. When the throttle valve 11 is opened when the engine 1 attempts to shift from deceleration operation to normal operation,
The idle signal IDL is turned off, and the fuel cut flag X
FC is set to off.

Returning to the description of the routine of FIG. Step 1
In the case of fuel cut during deceleration at 11, the EC
U36 determines in step 112 that the gas phase injection flag X
FI1 is set to OFF, and the subsequent processing is temporarily ended.
On the other hand, if the fuel cut during deceleration is not being performed in step 111, the ECU 36 determines in step 113 that
The gas phase injection flag XFI1 is set to ON.

Step 12 shifts from step 113
0, the ECU 36 determines the first fuel temperature T based on the signals from the first fuel temperature sensor 23 and the fuel pressure sensor 24.
The values of F1 and the first fuel pressure PF1 are read.

In step 121, the ECU 36
The fuel state is calculated based on the read fuel temperature TF1 and fuel pressure PF1. The ECU 36 performs this calculation based on the function data shown by the graph in FIG.

In step 122, the ECU 36
It is determined whether or not the calculated fuel state is a gas phase fuel. That is, when the calculation result of the fuel state corresponds to a region below the curve shown in FIG. 6, the ECU 36 determines the fuel state as gas-phase fuel. If the determination is for gas phase fuel, the ECU 36 shifts the processing to step 123. If the determination is not gas phase fuel, the ECU 36 shifts the processing to step 131. Here, the case where the LPG fuel is not determined to be the gas phase fuel means that the LPG fuel in the gas phase pipe 18 is an incomplete gas phase fuel. This is very rare.

In step 123, the ECU 36
Based on signals from the rotation sensor 7 and the air flow meter 10, the values of the engine rotation speed NE and the intake air amount Qa are read, respectively.

In step 124, the ECU 36
The value of the unit intake air amount Ga is calculated based on the read engine speed NE and the intake air amount Qa.

In step 125, the ECU 36
Values of the above-mentioned engine speed NE and unit intake air amount Ga,
Further, the value of the gas-phase injection amount TAU1 is calculated based on various correction values. In this calculation, the ECU 36 calculates the gas-phase basic injection amount TBS1 based on the function data as shown in the graph of FIG. In this function data, the gas-phase basic injection amount TBS1 is predetermined using the engine speed NE and the unit intake air amount Ga as parameters. For example, the engine rotation speed NE is the lowest and the unit intake air amount Ga
Is the smallest, the gas-phase basic injection amount TBS1 is “a2
1 ". As the engine speed NE becomes higher than the above condition, the gas phase basic injection amount TB
S1 increases to “a22”, “a23”,..., “A27”. Here, an increase in the number indicates an increase in the gas-phase basic injection amount TBS1 with an increase in the engine rotation speed NE. On the other hand, as the unit intake air amount Ga becomes larger than the above condition, the gas-phase basic injection amount TBS1 becomes “b21”, “c2”.
1 ",..." G21 ". Here, the alphabetical order indicates an increase in the gas-phase basic injection amount TBS1 with an increase in the unit intake air amount Ga. Gas phase basic injection amount T
The value of BS1 corresponds to the valve opening time of the gas phase injector 16, and the length of the valve opening time is determined by the injector 1
This is reflected in the amount of fuel injected from 6. The function data shown in FIG. 9 is based on the gas-phase basic injection amount TB with respect to the engine speed NE and the unit intake air amount Ga so that the injection characteristics of the gas-phase injector 16 match the required characteristics of the engine 1.
The value of S1 is set. The function data shown in FIG. 8 is also used to adjust the injection characteristics of the liquid injector 25 to the required characteristics of the engine 1 in the same manner.
The value of S2 is set. In that sense, FIG.
9 have different characteristics from each other. And
The ECU 36 reflects the various correction values, such as the high temperature correction, the intake air temperature correction, and the air-fuel ratio correction, on the gas phase basic injection amount TBS1 calculated as described above in the same manner as described above. The value of the phase injection amount TAU1 is calculated.

Then, at step 126, the ECU
The control unit 36 controls the gas-phase injector 16 based on the calculated value of the gas-phase injection amount TAU1 to inject the gas-phase fuel into the intake passage 2. Thereafter, the ECU 36 once ends the processing.

Step 13 after shifting from step 122
1, the ECU 36 determines the engine speed N based on signals from the rotation sensor 7 and the air flow meter 10.
The values of E and the intake air amount Qa are read, respectively.

In step 132, the ECU 36
The value of the unit intake air amount Ga is calculated based on the read engine speed NE and the intake air amount Qa.

In step 133, the ECU 36
The value of the quasi-gas-phase injection amount TAU3 is calculated based on the engine speed NE and the unit intake air amount Ga. ECU
36 performs this calculation based on predetermined function data. This function data is set so that the injection amount is relatively smaller than the function data shown by the graph in FIG. Again, the value of the quasi-gas phase injection amount TAU3 corresponds to the valve opening time of the gas phase injector 16, and the length of this valve opening time is reflected in the amount of fuel injected from the injector 16.

Then, at step 134, the ECU
The control unit 36 controls the gas-phase injector 16 based on the calculated value of the quasi-gas-phase injection amount TAU3 to inject LPG fuel into the intake passage 2 in a state similar to the gas-phase fuel.
Thereafter, the ECU 36 once ends the processing.

According to the above fuel supply control, the engine 1
In the normal operation of, when the LPG fuel in the liquid-phase pipe is actually liquid-phase fuel, the liquid-phase injector 25 supplies the liquid-phase fuel to the engine 1. On the other hand, when the LPG fuel in the liquid-phase pipe 26 is actually a gas-phase fuel instead of a liquid-phase fuel, the LPG fuel by the liquid-phase injector 25
The supply of PG fuel is prohibited. Then, the gas-phase fuel or the quasi-gas-phase fuel is supplied to the engine 1 by the gas-phase injector 16 instead of the liquid-phase injector 25.

On the other hand, when the gas-phase injector 16 supplies the gas-phase fuel to the engine 1 during the normal operation except the deceleration state, the engine 1 shifts to the deceleration operation and the fuel cut is performed. The injection flag XFI1 is set to off. Thereafter, when the operation returns from the deceleration operation with the fuel cut to the normal operation, and the LPG fuel in the liquid phase pipe 26 at that time indicates a liquid phase state, the deceleration operation with the fuel cut is changed from the deceleration operation to the normal operation. The liquid fuel is injected by the liquid injector 25 from the first injection of the return. That is, in this fuel supply control, switching from the injection of the gaseous phase fuel to the injection of the liquid phase fuel is performed by the liquid phase pipe 26.
Is performed when the LPG fuel in the fuel cell has transitioned from the gas phase state to the liquid phase state, and when the engine 1 has returned from the deceleration operation with the fuel cut to the normal operation. On the other hand, regarding the switching from the injection of the liquid phase fuel to the injection of the gas phase fuel, regardless of the return from the deceleration operation accompanied by the fuel cut to the normal operation, the liquid phase pipe 26 and the gas phase pipe 16 are switched.
Will be performed based only on the determination of the state of the LPG fuel.

FIGS. 4 and 5 are flowcharts respectively showing the contents of the throttle control program. FIG. 4 shows the contents of a control program performed during normal operation, and FIG.
Shows the contents of the control program at the time of the first idling operation performed in response to the fuel supply control.

The control program shown in FIG.
36 periodically executes this routine at a timing of a predetermined period.

In step 300, the ECU 36 reads the value of the accelerator opening ACCP from the accelerator sensor 14, or the change value of the opening ACCP.

In step 310, the ECU 36
Based on the value of the read accelerator opening ACCP,
The value of the target throttle opening TTA is calculated. ECU36
Performs this calculation based on predetermined function data.

Then, at step 320, the ECU
The reference numeral 36 controls the motor 12 based on the calculated target throttle opening TTA in order to determine the opening of the throttle valve 11. In this manner, the opening of the throttle valve 11 is controlled by the accelerator pedal 13 by the driver.
It is adjusted according to the operation of.

On the other hand, when the engine 1 is started, the ECU 36 periodically executes this routine for a predetermined period, for example, at a timing of 4 ms in accordance with the control program shown in FIG.

In step 400, the ECU 36
Starter switch 6, rotation sensor 7, water temperature sensor 8, and starter signal ST from accelerator sensor 14, engine speed NE, cooling water temperature THW, and accelerator opening ACC.
Read each value of P.

In step 405, the ECU 36
The read starter signal ST, engine speed N
E, it is determined whether or not the current state is the first idle operation of the engine 1 based on the values of the cooling water temperature THW and the accelerator opening ACCP. The first idling operation means the first idling operation immediately after the completion of the start performed in the cold state after the engine 1 is left in a stopped state for a while. The ECU 36 determines completion of the start based on the starter signal ST, and determines that the engine is in the first idle operation based on the engine speed NE, the coolant temperature THW, and the accelerator opening ACCP. If it is not during the first idling operation, the ECU 36 temporarily ends the subsequent processing. If it is the first idling operation, the ECU 36 shifts the processing to step 410.

In step 410, the ECU 36
It is determined whether or not the current fuel supply control is in the gas-phase injection mode in which the gas-phase injector 16 is operating.

If the determination is in the gas phase injection mode, E
In step 420, the CU 36 calculates a value of the target idle opening degree TIA1 in the gas-phase injection mode based on the read value of the cooling water temperature THW. On the other hand, if the above-described determination is the liquid-phase injection mode in which the liquid-phase injector 25 is operating, the ECU 36 determines in step 430 the liquid-phase injection mode based on the read coolant temperature THW. Of the target idle opening TIA2 is calculated. The ECU 36 performs these calculations based on function data as shown in FIG. In these function data, the target idle opening TIA1 calculated in the gas phase injection mode is relatively larger than the target idle opening TIA2 calculated in the liquid phase injection mode for the same value of the coolant temperature THW. Is set. This is to compensate for the fact that the amount of air supplied to the engine 1 through the intake passage 2 may be reduced by the gaseous fuel having a large space occupancy.

In step 440 after shifting from step 420 or step 430, the ECU 36 reads the actual value of the throttle opening TA from the throttle sensor 15.

In step 450, the ECU 36
It is determined whether or not the actual value of the throttle opening TA is larger than the calculated target throttle opening TIA1 or target throttle opening TIA2.

In this determination, if the actual value of the throttle opening TA is larger, the ECU 36
Is controlled, the throttle valve 11 is closed by a predetermined amount. That is, the opening of the throttle valve 11 is reduced by a predetermined amount. On the other hand, in this determination, if the actual value of the throttle opening TA is not larger, the ECU 3
6 opens the throttle valve 11 by a predetermined amount by controlling the motor 12. That is, the throttle valve 1
1 is increased by a predetermined amount. Then, after completing the processes of steps 460 and 470, the ECU 36 once ends this routine.

According to the throttle control at the time of the first idling operation, during the first idling operation, the values of the target idle opening degrees TIA1 and TIA2 according to the gas phase injection mode or the liquid phase injection mode are determined, and the target idle opening is determined. The throttle opening degree TA is adjusted so that the degrees become TIA1 and TIA2. Here, the amount of air supplied to the engine 1 together with the gas phase fuel in the gas phase injection mode is relatively the same as the amount of air supplied to the engine 1 together with the liquid phase fuel in the liquid phase injection mode. The opening of the throttle valve 11 is controlled in the gas-phase injection mode so that the throttle opening TA is on the opening side as compared with in the liquid-phase injection mode, that is, so that the same intake air amount Qa is obtained.

As described above, according to the configuration of the liquefied gas fuel supply device of the present embodiment, the second fuel temperature TF2 and the fuel temperature of the LPG fuel supplied to the liquid phase injector 25 through the liquid phase pipe 26 The value of the pressure PF2 is detected. The fuel temperature TF2 and the fuel pressure PF
Based on the value of 2, it is determined whether the state of the LPG fuel is liquid phase fuel. When it is determined that the LPG fuel is liquid fuel, the liquid injector 25 is controlled in the liquid injection mode, and the liquid fuel is injected and supplied to the engine 1.

On the other hand, when the state of the LPG fuel is not the liquid phase fuel, the gas phase injector 1
Fuel temperature TF1 related to the LPG fuel supplied to the fuel cell 6
And the value of the fuel pressure PF1 are detected. Based on the values of the fuel temperature TF1 and the fuel pressure PF1, LP
It is determined whether the state of the G fuel is gas phase fuel. When it is determined that the LPG fuel is the gaseous fuel, the gaseous phase injector 16 is controlled in the gaseous fuel injection mode, and the gaseous fuel is injected and supplied to the engine 1.
If the LPG fuel is not determined to be a gaseous fuel, it is determined that the LPG fuel is an incomplete gaseous fuel.
6 is controlled so that the quasi-gas phase fuel is injected and supplied to the engine 1.

Accordingly, under the condition that the LPG fuel in the gas phase pipe 18 is hard to be vaporized, such as at the time of the cold start of the engine 1, the gas phase fuel is supplied to the engine 1 by the gas phase injector 16. Therefore, the liquid-phase injector 25 supplies the liquid-phase fuel to the engine 1 properly. On the other hand, under the condition that the temperature of the engine 1 and the surrounding environment becomes high enough to vaporize the LPG fuel in the liquid phase pipe 26, the liquid phase fuel is supplied to the engine 1 by the liquid injector 25. Without
The gas-phase injector 16 supplies the gas-phase fuel to the engine 1 properly.

As described above, the LPG in the liquid phase piping 26
Whether or not the fuel is in the liquid phase reflects the temperature state of the engine 1, and it is determined whether or not the fuel is at an extremely high temperature, which is observed when the engine 1 is restarted after high-speed running. It also means to judge. Therefore, the above description is based on the case where the temperature of the engine 1 is not extremely high, the liquid injector 25 is controlled to supply the liquid fuel to the engine 1, and the temperature of the engine 1 is extremely high. This means that the gas-phase injector 16 is controlled and the gas-phase fuel is supplied to the engine 1.

Therefore, when the temperature of the engine 1 becomes low enough to make the LPG fuel difficult to vaporize, the gas-phase fuel is not supplied to the engine 1 by the gas-phase injector 16 and the liquid-phase fuel is supplied by the liquid-phase injector 25. Is supplied to the engine 1 in an appropriate amount. In contrast, LP
When the temperature of the engine 1 becomes high enough to vaporize the G fuel excessively, the liquid-phase injector 25 does not supply the liquid-phase fuel to the engine 1, and the gas-phase injector 16 supplies the engine 1 with a proper amount of the gas-phase fuel. 1 will be supplied.

As described above, the supply of the gas-phase fuel or the liquid-phase fuel to the engine 1 is switched based on the fuel state that can be changed by reflecting the temperature state of the engine 1. Therefore, at extremely low temperatures where the LPG fuel in the cylinder 17 does not evaporate and no gaseous phase fuel can be obtained, the supply control of the gaseous phase fuel is not performed, and the supply control of the liquid phase fuel is performed instead. An appropriate amount of liquid fuel is supplied to the engine 1. As a result, even at extremely low temperatures, the startability of the engine 1 and the stability of idling after the start is completed can be secured.

In addition, in this embodiment, the engine 1
Supply of gaseous or liquid phase fuel to the actual LPG
It is switched according to the state of the fuel. For this reason, unlike the conventional control device, the supply of the gaseous fuel and the supply of the liquid fuel are not frequently switched according to a change in the load or the rotation speed of the engine 1 between high and low. In this sense, good controllability and responsiveness can be ensured including the transition period of the LPG fuel supply switching.

According to the configuration of this embodiment, the parameters indicating the state of the LPG fuel are used as the fuel temperature sensors 23 and 31.
And the fuel temperatures TF1, TF2 and the fuel pressures PF1, PF2 detected by the fuel pressure sensors 24, 32. Then, the fuel state is calculated based on those parameters, and it is determined whether the fuel is a liquid phase fuel or a gas phase fuel. For this reason, it is possible to accurately determine whether the LPG fuel is actually a liquid-phase fuel or a gas-phase fuel, thereby improving the control accuracy of the present apparatus.

According to the configuration of this embodiment, when the idle switch of the throttle sensor 15 is turned on and the operating state of the engine 1 detected thereby indicates a deceleration operation, all the injectors 16 and 25 are forced to operate. And the supply of liquid-phase fuel and gas-phase fuel to the engine 1 is forcibly shut off (fuel cut), thereby saving LPG fuel. On the other hand, the fuel temperature TF2 and the fuel pressure P detected by the fuel temperature sensor 31 and the fuel pressure sensor 32, respectively.
The case where the state of the LPG fuel determined based on the value of F2 has shifted from the gas phase to the liquid phase, and the operating state of the engine 1 detected by the throttle sensor 15 is from the deceleration operation with fuel cut to the normal operation. To return to the gas phase injector 1 that was performed immediately before the fuel cut.
The fuel supply mode is switched from the injection of the gaseous fuel by the liquid injector 6 to the injection of the liquid fuel by the liquid injector 25. That is, the mode is switched from the gas phase injection mode to the liquid phase injection mode.

Therefore, the fuel (residual fuel) remaining on the intake passage 2, particularly the inner wall of the intake port immediately adjacent to the combustion chamber, immediately before the fuel cut is performed, the fuel is cut at the time of deceleration. In the meantime, it is sucked into the combustion chamber and cleared. When the residual fuel is almost exhausted, the mode is switched from the gas phase injection mode to the liquid phase injection mode, and the liquid fuel is injected from the first time. For this reason, when switching to the liquid phase injection at the time of return from the fuel cut, it is possible that the residual fuel is added to the liquid phase fuel injected from the liquid phase injector 25 and the amount of fuel supplied to the combustion chamber becomes excessive. Absent. As a result, it is possible to prevent the air-fuel ratio of the engine 1 from becoming over-rich, and to prevent deterioration of the exhaust emission of the engine 1.

If there is no fuel supply switching control as described above, for example, switching from gas-phase injection to liquid-phase injection during idling operation of the engine 1 may occur. In such a case, if the gas phase injection is stopped and the liquid phase injection is started at the same time, the flow of air in the intake passage 2 becomes relatively slow because the engine speed NE is low during the idling operation. ing. When the liquid phase fuel is injected in such a state, the liquid phase fuel is injected at a higher speed than the air flow, and together with the residual fuel by the gas phase injection immediately before the fuel cut, the liquid fuel is injected into the combustion chamber. There is a possibility that the amount of supplied fuel becomes temporarily excessive, the air-fuel ratio becomes over-rich, and the exhaust emission deteriorates. The switching control of the fuel supply in the present embodiment can cope with the above-described problem.

On the other hand, in the present embodiment, the switching from the injection of the liquid-phase fuel to the injection of the gas-phase fuel is performed regardless of the return from the fuel cut.
6 based on the determination of the state of the LPG fuel only. This has the following advantages for the operation of the engine 1.

That is, for example, there is a case where the vehicle is left in idle operation after traveling at high speed, that is, a case where “hot soak” occurs. Here, during high-speed running, the engine 1
Consumes a large amount of fuel and increases the calorific value,
Because of the traveling wind, the area around the engine 1 is appropriately cooled. However, during hot soak,
The running wind disappears, and the temperature around the engine 1, especially the intake system and the fuel supply system, rises extremely. In such a case, the LPG fuel in the liquid phase pipe 26 changes state from liquid phase fuel to gas phase fuel. Therefore, if the liquid-phase injection mode continues in such a situation, the gas-phase fuel will be injected from the liquid-phase injector 25, and the air-fuel ratio will become over-lean and the engine 1 may stop. . On the other hand, during the high-speed running, the engine cooling water is at a high temperature.
The fuel in the gas phase pipe 33 is in a sufficiently gas phase state. For this reason, when shifting from liquid-phase fuel injection to gas-phase fuel injection, it is better to switch the injection mode based only on the determination of the state of the LPG fuel in each of the pipes 26 and 16. It is possible to immediately switch to injection of gaseous phase fuel rather than adding the return from the condition to the condition. Even if the liquid fuel is injected during the hot soak, the fuel gas is not filled in the intake passage 2. At that time, the injection of the liquid fuel is stopped, and the injection of the gaseous fuel is immediately started. Even if started, exhaust emission and drivability do not deteriorate.

According to the configuration of this embodiment, immediately after the start of the engine 1, particularly when the gas-phase fuel or the liquid-phase fuel is supplied to the engine 1 during the first idling operation,
The motor 12 is controlled so that the opening degree T of the throttle valve 11 is controlled.
A is adjusted automatically. Here, at the time of gas-phase fuel injection, the amount of air supplied to the engine 1 together with the gas-phase fuel is controlled by controlling the opening degree TA of the throttle valve 11 to be more open than at the time of liquid-phase fuel injection. It is adjusted to be relatively the same as the amount of air supplied to the engine 1 together with the liquid phase fuel.

Therefore, even when the amount of air supplied to the engine 1 during the first idle operation is likely to be reduced by mixing with the gas-phase fuel, the shortage of the amount of air is compensated. As a result, it is possible to suppress the output shortage of the engine 1 when the gas-phase fuel is supplied during the first idle operation, and to stabilize the idle operation.

According to this embodiment, the return pipe 33 connected to the liquid phase pipe 26 is connected to the liquid phase injector 25.
Is provided so that part or all of the liquid fuel supplied to the liquid injector 25 is returned to the cylinder 17. Therefore, the liquid-phase injector 25 can be cooled by the liquid-phase fuel flowing through the two pipes 26 and 33, and the air bubbles entering the liquid-phase pipe 26 can be discharged through the return pipe 33. In this sense, the properties of the liquid fuel injected from the liquid injector 25 can always be maintained as appropriate.

The present invention is not limited to the above-described embodiment, but can be carried out as follows without departing from the spirit of the invention.

(1) In the above embodiment, the processing of steps 110 to 113 is added to the fuel supply control program shown in FIG. 2 to change the state of the LPG fuel in the liquid phase pipe 26 from the gas phase to the liquid phase. Only when the engine has shifted to the phase and when the engine 1 returns from the deceleration operation with the fuel cut to the normal operation, the injection from the gas phase fuel is switched to the injection of the liquid phase fuel. On the contrary,
These processes may be omitted.

(2) In the above embodiment, the gas-phase fuel or the liquid-phase fuel is supplied to the engine 1 by the gas-phase injector 16 and the liquid-phase injector 25 provided one each in the intake passage 2. On the other hand, a configuration may be adopted in which a gas-phase injector and a liquid-phase injector are arranged in each of a plurality of cylinders of an engine.

(3) In the above embodiment, the link-less type throttle valve 11 is used as the air amount adjusting means of the present invention to control the air amount during the first idle operation as shown in FIG. On the other hand, a bypass passage bypassing the throttle valve and an idle speed control valve (ISC valve) for opening and closing the bypass passage are provided as air amount adjusting means in the intake passage. Air amount control during operation may be performed.

[0094]

According to the first aspect of the present invention,
The supply of the gas-phase fuel or the liquid-phase fuel to the engine is switched based on the state of the liquefied gas fuel. Therefore, when it is difficult to vaporize the liquefied gas fuel, the liquid phase fuel is appropriately supplied to the engine. When the liquefied gas fuel is excessively vaporized, the gaseous phase fuel is properly supplied to the engine. Will be. As a result, it is possible to ensure the startability of the engine at a low temperature and the stability of idling after the start, and further, it is possible to ensure the controllability and responsiveness of the device.

According to the second aspect of the invention, in addition to the function of the first aspect, the parameter indicating the state of the liquefied gas fuel is specifically specified based on the detected temperature and pressure. It is determined whether it is a liquid phase or a gas phase.
For this reason, in addition to the effect of the first aspect of the present invention, it is possible to accurately determine whether the LPG fuel is actually a liquid phase fuel or a gas phase fuel, and it is possible to enhance the control accuracy of the present apparatus. It has the effect.

According to a third aspect of the present invention, in the first or second aspect of the present invention, the state of the liquefied gas fuel changes from a gas phase to a liquid phase, and When the engine returns from the deceleration operation accompanied by the fuel cut to the normal operation, the supply is switched from the supply of the gaseous fuel to the supply of the liquid fuel. Therefore, in addition to the operation of the invention of claim 1 or claim 2, the fuel remaining in the engine until immediately before is removed during the fuel cut, and then the supply of gaseous fuel is switched to the supply of liquid fuel. The amount of fuel supplied to the engine will not be excessive. For this reason, in addition to the effect of the invention of claim 1 or claim 2, it is possible to prevent the air-fuel ratio in the engine from becoming temporarily rich, and in this sense, it is possible to prevent deterioration of the exhaust of the engine. It has the effect of being able to do it.

According to the structure of the invention described in claim 4, in the structure of the invention of claims 1 to 3, the case where the gas phase fuel is supplied to the engine immediately after the start of the engine;
A relatively same amount of air is supplied to the engine when liquid fuel is supplied to the engine. Therefore, in addition to the effects of the inventions of claims 1 to 3, even if the amount of air supplied to the engine may be reduced by mixing with the gas-phase fuel, the shortage of the amount of air is compensated. As a result, in addition to the effects of the inventions of claims 1 to 3, when the gaseous phase fuel is supplied at the time of idling operation after starting, it is possible to suppress the engine output from becoming insufficient, and to stabilize the idling operation. The effect that it can be achieved is exhibited.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing a liquefied gas fuel supply device for an engine according to one embodiment.

FIG. 2 is a flowchart showing the contents of a fuel supply control program.

FIG. 3 is a flowchart showing the contents of a fuel cut control program.

FIG. 4 is a flowchart showing the contents of a throttle control program.

FIG. 5 is a flowchart showing the contents of a throttle control program during a first idle operation.

FIG. 6 is a graph showing function data set for a fuel state.

FIG. 7 is a graph showing function data set for a target idle opening degree.

FIG. 8 is a graph showing function data similarly set for the liquid phase basic injection amount.

FIG. 9 is also a graph showing function data set for the gas phase basic injection amount.

[Explanation of symbols]

 Reference Signs List 1 LPG engine 6 starter switch 7 rotation sensor 8 water temperature sensor 10 air flow meter 14 accelerator sensor 15 throttle sensor 16 gas-phase injector 17 cylinder 18 gas-phase pipe 25 liquid-phase injector 26 liquid-phase pipe 30 pump 31 second fuel temperature sensor 32 first 2 fuel pressure sensor 36 ECU

Claims (4)

[Claims] 1. A liquid fuel supply means for supplying a liquefied gas fuel contained in a cylinder as a liquid fuel to an engine, and supplying the liquefied gas fuel contained in the cylinder as a gaseous fuel to the engine. Gas state fuel supply means for detecting the state of the liquefied gas fuel supplied from the cylinder to the liquid phase fuel supply means; and Controlling the liquid-phase fuel supply means to supply the liquid-phase fuel to the engine when the liquid-phase fuel is in a phase; A supply control means for controlling a supply means to supply the gaseous phase fuel to the engine. 2. The liquefied gas fuel supply device for an engine according to claim 1, wherein the fuel state detecting means detects a temperature of the liquefied gas fuel and a pressure of the liquefied gas fuel. And a supply sensor, wherein the state of the liquefied gas fuel is a liquid phase or a gas phase based on a temperature and a pressure detected by the temperature sensor and the pressure sensor. Liquefied gas fuel supply apparatus for an engine, comprising: 3. The liquefied gas fuel supply device for an engine according to claim 1 or 2, wherein an operating state detecting means for detecting an operating state of the engine; and When deceleration is indicated, the supply of fuel by the liquid-phase fuel supply means and the gas-phase fuel supply means is interrupted, and the state of the detected liquefied gas fuel shifts from a gas phase to a liquid phase. ,
And when the detected operating state indicates a return from the deceleration of the engine to a normal operation, the switching from the supply of fuel by the gas-phase fuel supply unit to the supply of fuel by the liquid-phase fuel supply unit. A liquefied gas fuel supply device for an engine, comprising: a supply switching unit. 4. The liquefied gas fuel supply device for an engine according to claim 1, wherein the engine controls an amount of air supplied to the engine along with the supply of the fuel. Having an air amount adjusting means whose opening degree is controlled to adjust the amount of air supplied to the engine together with the gas-phase fuel when the engine is started; Air amount control means for controlling the air amount adjustment means so as to be relatively the same as the amount of air so as to be on the open side during the supply of the gaseous phase fuel than during the supply of the liquid phase fuel. A liquefied gas fuel supply device for an engine, comprising: