JPH11159372A - Injection control system for accumulator type multi-cylinder engine - Google Patents

Abstract

(57) Abstract: In an injection control device for a pressure-accumulation type multi-cylinder engine, a decrease in controllability of fuel injection is prevented without increasing cost. An injector (2) is connected to a common rail (4) common to each cylinder. Basically, while an electromagnetic valve (3) is open, high-pressure fuel in the common rail (4) is supplied from the injector (2) to each cylinder (# 1 to # 4). It is injected. Electronic control unit (EC
U) 51 calculates a correction injection pressure based on the calculated fuel injection amount, obtains an injection fuel pressure based on the corrected injection pressure, and corrects it by reflecting it in the valve opening time. Therefore, the injection causes a pressure pulsation inside the injection system, and even if a phenomenon occurs in which the generated pressure reflected wave is synchronized with the injection period of the next injection cylinder, the influence of the pressure reflected wave is considered. In addition, the valve opening time is controlled, and an optimal fuel amount is secured for the operating state and the pressure pulsation state of the diesel engine 1 at that time.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an injection control device for an accumulator-type multi-cylinder engine, and more particularly, to an accumulator system for injecting high-pressure fuel accumulated in an accumulator pipe from a fuel injection valve to each cylinder of the engine. The present invention relates to an injection control device for a multi-cylinder engine.

[0002]

2. Description of the Related Art Conventionally, an accumulator type fuel injection device has been known as one of fuel injection devices for a diesel engine, for example. This device accumulates high-pressure fuel from a supply pump in an accumulator pipe called a common rail, and injects this into each cylinder of the engine by opening a fuel injection valve.

As described above, in the technology of the type in which the high-pressure fuel stored in the common rail is injected from the fuel injection valve to each cylinder of the engine, every time the injection is performed for each cylinder, the pressure inside the injection system is increased. Pulsation can occur. At this time, a phenomenon in which the pressure reflected wave is synchronized with the injection period of the next injection cylinder may occur. Therefore, there is a problem that the influence of the pressure reflected wave affects the next injection, and as a result, the controllability of the fuel injection is reduced.

As a technique for solving such a problem, for example, a technique disclosed in Japanese Patent Application Laid-Open No. Hei 4-252860 is known. In this technique, a check valve is provided between the fuel injection valve and the common rail in order to prevent the above-mentioned problem from occurring. According to this technique, the transmission of the pressure reflected wave is regulated by the presence of the check valve, and the situation in which the pressure reflected wave is synchronized with the injection period of the next injection cylinder as described above can be suppressed. .

[0005]

However, in the above-mentioned prior art, it is necessary to provide a check valve corresponding to each cylinder, so that the number of parts and the cost are increased.

In the above technique, a check valve is provided on the downstream side of the common rail, so that the presence of the check valve impedes a smooth flow of accumulated fuel during injection. For this reason, the fuel pressure may be reduced, which may cause a situation where the fuel pressure originally required for the injection cannot be secured. As a result, there still remains a problem that the controllability of the fuel injection is reduced, for example, the output fluctuates and the drivability is deteriorated.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and has as its object to provide a pressure-accumulating multi-cylinder engine in which high-pressure fuel accumulated in a pressure accumulating pipe is injected from a fuel injection valve to each cylinder of the engine. It is an object of the present invention to provide an injection control device for a pressure-accumulating multi-cylinder engine which can prevent a decrease in controllability of fuel injection without increasing cost.

[0008]

In order to achieve the above object, according to the first aspect of the present invention, a high pressure fuel is supplied from a supply pump, and a pressure accumulating pipe for accumulating the high pressure fuel is connected to the pressure accumulating pipe. A fuel injection valve for injecting fuel into each cylinder of the engine; an operation state detection means for detecting an operation state of the engine; and a fuel injection valve for the fuel injection valve based on a detection result of the operation state detection means. Pulsation detecting a fuel pressure pulsation state in the pressure accumulation pipe in an injection control device for a pressure accumulation type multi-cylinder engine, comprising: an injection control means for determining a valve opening period and controlling a fuel injection valve based on the valve opening period. The gist of the invention is to provide a state detecting means and a valve opening period correcting means for correcting the valve opening period in accordance with the fuel pressure pulsating state detected by the pulsating state detecting means.

According to the second aspect of the present invention, high-pressure fuel is supplied from a supply pump, and a pressure-accumulation pipe for accumulating the high-pressure fuel is connected to the pressure-accumulation pipe to inject fuel into each cylinder of the engine. A fuel injection valve, an operating state detecting means for detecting an operating state of the engine, and an injection timing by the fuel injection valve based on a detection result of the operating state detecting means. In an injection control device for a pressure-accumulation type multi-cylinder engine having an injection control means for controlling an injection valve, a pulsation state detection means for detecting a pulsation state of fuel pressure in the pressure accumulation pipe, and a pulsation state detected by the pulsation state detection means. The gist is that an injection timing correction means for correcting the injection timing according to the fuel pressure pulsation state is provided.

Further, according to the third aspect of the present invention, a high-pressure fuel is supplied from a supply pump, and a pressure-accumulation pipe for accumulating the high-pressure fuel, and is connected to the pressure-accumulation pipe to inject fuel into each cylinder of the engine. A fuel injection valve, operating state detecting means for detecting the operating state of the engine,
An injection control unit that determines a valve opening period of the fuel injection valve and an injection timing by the fuel injection valve based on a detection result of the operating state detection unit, and controls the fuel injection valve based on the valve opening period and the injection timing; In the injection control device for a pressure-accumulation type multi-cylinder engine, comprising: a pulsation state detection means for detecting a fuel pressure pulsation state in the pressure accumulation pipe, and a fuel pressure pulsation state detected by the pulsation state detection means. The gist of the invention is to provide a correction means for correcting the valve opening period and the injection timing.

According to a fourth aspect of the present invention, in the injection control apparatus for a pressure-accumulation type multi-cylinder engine according to any one of the first to third aspects, the pulsation state detecting means may include a pulsating state detecting means for the engine. The gist of the invention is to detect a fuel pressure pulsation state based on a fuel pressure fluctuation state that is previously empirically determined according to a load and a rotation speed.

According to a fifth aspect of the present invention, in the injection control apparatus for a pressure accumulating multi-cylinder engine according to any one of the first to third aspects, the pulsation state detecting means includes at least a fuel injection valve. The gist is to detect a fuel pressure pulsation state in consideration of a pressure wave component due to valve closing.

(Operation) According to the first aspect of the present invention, the high pressure fuel from the supply pump is supplied to the pressure accumulation pipe, and the high pressure fuel is accumulated in the pressure accumulation pipe. Fuel is injected into each cylinder of the engine from a fuel injection valve connected to the pressure accumulation pipe. Further, the operating state of the engine is detected by the operating state detecting means. Then, based on the detection result, the injection control means determines the valve opening period of the fuel injection valve, and controls the fuel injection valve based on the valve opening period.

In the present invention, the pulsating state of the fuel pressure in the pressure accumulating pipe is detected by the pulsating state detecting means. The valve opening period correcting means corrects the valve opening period in accordance with the fuel pressure pulsating state detected by the pulsating state detecting means. Therefore, even if pressure pulsation occurs,
An appropriate fuel injection amount can be secured without using a new pressure pulsation prevention member separately.

Further, according to the present invention, the flow of fuel is not hindered by providing the separate pressure pulsation preventing member. For this reason, it is possible to prevent a decrease in fuel pressure due to hindering a smooth flow of fuel.

Further, according to the second aspect of the present invention,
High pressure fuel from a supply pump is supplied to the pressure accumulating pipe, and the fuel is accumulated in the pressure accumulating pipe. Fuel is injected into each cylinder of the engine from a fuel injection valve connected to the pressure accumulation pipe. Further, the operating state of the engine is detected by the operating state detecting means. Then, based on the detection result, the injection control means determines the injection timing of the fuel injection valve, and controls the fuel injection valve based on the injection timing.

In the present invention, the pulsating state of the fuel pressure in the pressure accumulation pipe is detected by the pulsating state detecting means. Then, the injection timing is corrected by the injection timing correction means in accordance with the fuel pressure pulsation state detected by the pulsation state detection means. Therefore, even if pressure pulsation occurs,
Correcting the injection timing to the advance or retard side makes it possible to adapt the actual output to the required output. In the present invention, it is not necessary to use a new pressure pulsation prevention member separately.
And an operation equivalent to the operation of the invention described in (1).

In particular, according to the present invention, even if the injection pressure deviates from the required value, for example, to the required value due to the pressure pulsation, the injection timing is properly corrected.
The premixed gas ratio does not become too large. Therefore, a situation in which the combustion noise deteriorates is avoided.

In addition, according to the third aspect of the present invention,
The functions described in the first and second aspects are both achieved. Further, according to the invention described in claim 4,
In addition to the operation of the invention as set forth in claims 1 to 3, the pulsation state detecting means may determine the fuel pressure based on the fluctuation state of the fuel pressure which is empirically grasped in advance according to the engine load and rotation speed at that time. A pulsating state is detected. Therefore,
The fuel pressure pulsation state is accurately grasped, and the fuel injection amount is further optimized.

Furthermore, according to the invention described in claim 5. In addition to the effect of the invention described in claims 1 to 3, the pulsation state detecting means detects the fuel pressure pulsation state in consideration of at least a pressure wave component caused by closing the fuel injection valve. For this reason, the valve opening period, and hence the fuel injection amount is corrected in consideration of the pressure wave component that can greatly affect the pressure pulsation, and the fuel injection amount is further optimized.

[0021]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS (First Embodiment) A first embodiment of a fuel injection type multi-cylinder engine injection control apparatus according to the present invention will now be described in detail with reference to the drawings.

FIG. 1 is a schematic configuration diagram showing an injection control device of a pressure accumulating diesel engine mounted on a vehicle in the present embodiment. The diesel engine 1 is provided with a plurality of cylinders (four cylinders in the present embodiment) # 1 to # 4, and an injector 2 as a fuel injection valve is provided to a combustion chamber of each of the cylinders # 1 to # 4. Are arranged. Each cylinder # 1 to # 4 of the diesel engine 1 from the injector 2
Is controlled by turning on / off the solenoid valve 3 for injection control.

The injector 2 is connected to a common rail 4 serving as a pressure accumulating pipe common to each cylinder. Basically, while the solenoid valve 3 for injection control is open, fuel in the common rail 4 is supplied from the injector 2. The fuel is injected into each of the cylinders # 1 to # 4. A relatively high pressure corresponding to the fuel injection pressure needs to be continuously accumulated in the common rail 4, particularly at the time of starting. Therefore, the common rail 4 is connected to the discharge port 6 a of the supply pump 6 via the supply pipe 5. A check valve 7 is provided in the middle of the supply pipe 5,
Due to this existence, the supply pump 6 and the common rail 4
Supply of fuel to the supply pump 6 from the common rail 4 to the supply pump 6 is regulated.

The supply pump 6 has a suction port 6b
Is connected to the fuel tank 8 via a filter 9, and a filter 9 is provided in the middle of the fuel tank 8. The supply pump 6 draws fuel from the fuel tank 8 via the filter 9. At the same time, the supply pump 6 reciprocates the plunger by a cam (not shown) synchronized with the rotation of the diesel engine 1 to increase the fuel pressure to a required predetermined pressure. Then, the supply pump 6 supplies high-pressure fuel to the common rail 4.

Further, the discharge port 6 of the supply pump 6
A pressure control valve 10 is provided near a. The pressure control valve 10 is for controlling the pressure of the fuel discharged from the discharge port 6a toward the common rail 4 (therefore, the discharge amount). The pressure control valve 10 closes its own valve body in response to the ON signal, and permits the supply of fuel from the discharge port 6a toward the common rail 4. The pressure control valve 10 opens its own valve element in response to the OFF signal, and supplies excess fuel not discharged from the discharge port 6 a from the return port 6 c provided in the supply pump 6 through the return pipe 11 to the fuel tank 8. To return to.

In the present embodiment, the common rail 4 is provided with a relief valve 12, and when a predetermined condition is satisfied, the relief valve 12 is opened. As a result, the high-pressure fuel in the common rail 4 is returned to the fuel tank 8 via the return pipe 11, and the pressure in the common rail 4 is reduced.

Further, in the injector 2 of the present embodiment, when the solenoid valve 3 is driven, not only does the fuel injection into each of the cylinders # 1 to # 4 be performed, but also the solenoid valve 3 is driven. During the initial period (hereinafter referred to as “ineffective injection time”), fuel is released and the common rail 4
It has a mechanism that can reduce the fuel pressure in the interior. Here, the mechanism will be described.

As shown in FIG. 2A, the injector 2
The casing 61 is provided with a supply port 62 so that the fuel from the common rail 4 passes through a supply pipe 63 and is introduced into a lower fuel storage chamber 64 formed at a lower portion of the casing 61. I have. Further, a nozzle hole 65 that can communicate with the lower fuel storage chamber 64 is formed at the lowermost portion of the casing 61. Further, the supply port 62 is connected to an upper fuel reservoir 67 via an orifice 66. One nozzle needle 68 is slidably provided in the lower fuel storage chamber 64 and the upper fuel storage chamber 67.

The nosle needle 68 is composed of a tip portion 69, a large diameter portion 70, a small diameter portion 71, and a piston portion 72 in this order from the lower side. The large diameter portion 70 connects the upper portion of the lower fuel storage chamber 64 with The piston portion 72 can slide vertically on a lower portion of the upper fuel storage chamber 67. A needle spring 73 is provided around the small diameter portion 71, and the urging force of the spring 73 always urges the nozzle needle 68 downward in the drawing. As a result, the tip 69 of the nozzle needle 68 is always in contact with the seat 74 near the nozzle hole 65.

The upper fuel storage chamber 67 communicates with an electromagnetic valve housing chamber 76 through an orifice 75. The electromagnetic valve 3 includes a valve body 77, a solenoid 78, a valve body spring 79, and the like, and these are housed in an electromagnetic valve housing chamber 76. That is, the valve body 77 is provided at a lower portion of the solenoid valve housing chamber 76, and the valve body spring 79 is provided so as to abut on the ceiling of the valve body 77 and the solenoid valve housing chamber 76. Therefore, the valve body 77 is always urged downward. As a result, the orifice 75 is always closed by the biased valve body 77, and the communication between the upper fuel storage chamber 67 and the solenoid valve housing chamber 76 is shut off. When the solenoid 78 itself is excited, the valve body spring 7
This is for raising the valve body 77 upward in the drawing against the urging force of No. 9. The upper portion of the valve body 77 is formed in a flange shape, and a through hole 77a is formed in the flange portion. The casing 61 has an electromagnetic valve housing chamber 76.
A return port 80 for allowing fuel from the fuel tank to escape is formed.
From 0, surplus fuel is returned to the fuel tank 8 via the return pipe 11. The space in which the needle spring 73 is provided and the solenoid valve accommodating chamber 76 are connected by a communication passage 81. Therefore, the fuel that leaks little by little into the space where the needle spring 73 is provided flows through the communication passage 81 into the solenoid valve housing chamber 76, and eventually through the through hole 77 and the return port 80, and returns to the return pipe 11. It gradually flows toward.

The injector 2 configured as described above
The operation of is described below, as shown in FIG.
First, when the solenoid 78 is not excited, the valve body 77 is urged downward by the urging force of the valve body spring 79, and the communication between the upper fuel storage chamber 67 and the electromagnetic valve housing chamber 76 is cut off. . Therefore, in such a situation, the fuel from the supply port 62 is uniformly supplied to the lower fuel storage chamber 64 and the upper fuel storage chamber 67, and the pressure balance is maintained. Accordingly, the nozzle needle 68 is provided with the needle spring 73.
The nozzle needle 68 is urged downward by the urging force of
Is maintained in contact with the seating portion 74 near the nozzle hole 65. Therefore, in this case, the fuel is not injected from the nozzle hole 65, and the fuel from the upper fuel storage chamber 67 does not quickly flow out through the return port 80.

On the other hand, when the solenoid 78 is excited,
The valve body 77 moves upward against the urging force of the valve body spring 79, and the upper fuel storage chamber 67 and the solenoid valve housing chamber 76
Communication is established between them. Then, for a while after that, the injector 2 behaves as shown in FIG. That is, since the valve element 77 moves upward, the fuel in the upper fuel storage chamber 67 flows from the return port 80 to the return pipe 11 through the through hole 77a. At this time,
For a while after the solenoid 78 is excited, the difference between the fuel pressure in the lower fuel chamber 64 and the fuel pressure in the upper fuel chamber 67 is still smaller than the urging force of the needle spring 73. For this reason, the nozzle needle 68 does not move, and the tip 69 remains in contact with the seating portion 74. Therefore, in this state, fuel is not injected from the nozzle hole 65, and fuel from the upper fuel storage chamber 67 quickly flows out through the return port 80. This period is the invalid injection time.

Then, the fuel in the upper fuel storage chamber 67 steadily escapes, and the difference between the fuel pressure in the lower fuel storage chamber 64 and the fuel pressure in the upper fuel storage chamber 67 becomes larger than the urging force of the needle spring 73. Figure 2
As shown in (c), the nozzle needle 68 moves upward by the fuel pressure in the lower fuel storage chamber 64. This allows
The distal end portion 69 is separated from the seating portion 74, and the lower fuel storage chamber 64 and the nozzle hole 65 communicate with each other. As a result, high-pressure fuel is injected from the nozzle hole 65.

Thereafter, when the excitation of the solenoid 78 is released, the injector 2 returns to the state shown in FIG. 2A, and the fuel injection ends. That is, the solenoid 78
If the excitation time is less than the invalid injection time,
Since the state shown in FIG. 2B does not shift to the state shown in FIG. 2C, the fuel is not injected and the fuel from the upper fuel reservoir 67 only flows out quickly through the return port 80. Become.

The combustion chamber of the diesel engine 1 is connected to an intake passage 13 and an exhaust passage 14, respectively. A throttle valve (not shown) is provided in the intake passage 13, and the flow rate of intake air introduced into the combustion chamber is adjusted by opening and closing the valve.

In the combustion chamber of the diesel engine 1, a glow plug 16 is provided. The glow plug 16 is connected to the glow relay 16 immediately before the engine 1 is started.
This is a start-up assisting device that makes the device red-heat by applying a current to a, and sprays a part of the fuel spray to promote ignition and combustion.

The diesel engine 1 is provided with the following various sensors and the like for detecting the state thereof, and these constitute an operating state detecting means in the present embodiment. That is, an accelerator sensor 21 for detecting the accelerator opening ACCP is provided near the accelerator pedal 15, and near the sensor 21,
A fully-closed switch 22 that outputs a fully-closed signal when the depression amount of the accelerator pedal 15 is zero is provided.

The intake passage 13 is provided with an intake pressure sensor 23 via a filter 17 and a vacuum switching valve (VSV) 18. The intake pressure sensor 23 detects the intake pressure (intake pressure PM) inside the intake passage 13.

Further, the cylinder block of the diesel engine 1 is provided with a water temperature sensor 24 for detecting the temperature of the cooling water (cooling water temperature THW). In addition, the diesel engine 1 is provided with a starter 19 for starting the engine 1. The starter 19 is provided with a starter switch 25 for detecting the operation state. The starter switch 25 operates when the ignition switch (not shown) is operated from the OFF position to the start position by the driver when the diesel engine 1 is started, and the starter is operated (when the engine is in the cranking state). Signal STA
Is output as “ON”. When the start of the diesel engine 1 is completed (it becomes a complete explosion state) or the start of the engine 1 fails and the ignition switch is returned from the start position to the ON position, the starter switch 25 starts the starter switch 25. The signal STA is output as “OFF”.

In addition, the return pipe 11 is provided with a fuel temperature sensor 26 for detecting the fuel temperature THF. In addition, the common rail 4 is provided with a fuel pressure sensor 27 for detecting the fuel pressure (fuel pressure PC) in the common rail 4.

In this embodiment, an NE sensor 28 is provided near a pulser provided on a crankshaft (not shown) of the diesel engine 1. Further, the rotation of the crankshaft is transmitted via a timing belt or the like to a camshaft (not shown) for opening and closing the intake valve 31 and the exhaust valve 32. The camshaft is set to rotate at a rotation speed of 1/2 of the crankshaft. A G sensor 29 is provided near the pulser provided on the camshaft. In the present embodiment, the engine speed NE is calculated based on the pulse signals output from the sensors 28 and 29, and the crank angle CA, the top dead center (TDC) of each of the cylinders # 1 to # 4. Is calculated (the cylinder is determined).

An intake air temperature sensor 30 for detecting an intake air temperature THA is provided near an air cleaner (not shown) at the entrance of the intake passage 13. In the present embodiment, an electronic control unit (ECU) 51 for controlling various controls of the diesel engine 1 is provided. The electrical configuration of the ECU 51 will be described with reference to the block diagram of FIG. The ECU 51 includes a central processing control unit (CPU) 52, a read-only memory (ROM) 53 in which predetermined programs and maps are stored in advance, a CPU 5
2 is provided with a random access memory (RAM) 54 for temporarily storing the calculation result and the like, a backup RAM 55 for storing previously stored data and the like, a timer counter 56, and the like, and an input interface 57 and an output interface 58 and the like. I have. In addition, each of the above sections 52
The input interface 57 and the output interface 58 are connected by a bus 59.

The above-described accelerator sensor 21, intake pressure sensor 23, water temperature sensor 24, fuel temperature sensor 26, fuel pressure sensor 27, intake temperature sensor 30, etc. are respectively provided with a buffer, a multiplexer, and an A / D converter (all not shown). ) Is connected to the input interface 57. Also,
The NE sensor 28 and the G sensor 29 are connected to an input interface 57 via a waveform shaping circuit. Further, the fully closed switch 22 and the starter switch 25 are directly connected to the input interface 57.

The CPU 52 includes the sensors 21 to 30 described above.
Is read through the input interface 57. The solenoid valve 3, the pressure control valve 10, the relief valve 12, and the VSV 18 are connected to an output interface 58 via a drive circuit (not shown). The CPU 52 suitably controls the solenoid valve 3, the pressure control valve 10, the relief valve 12, the VSV 18 and the like based on the input values read via the input interface 58.

Next, in this embodiment, the ECU 51
The fuel injection control among the controls executed by the ECU will be described. First, FIG. 4 is a flowchart showing an “injection control routine” executed by the ECU 51. This routine is executed by interruption every predetermined crank angle.

When the processing of this routine is started, the ECU
51, first, in step 101, various sensors 2
Accelerator opening ACC based on signals from 1 to 30 etc.
P, engine speed NE, fuel pressure PC, etc. are read.

Next, at step 102, the ECU 5
1 calculates the fuel injection amount Q based on the accelerator opening ACCP and the engine speed NE read this time. In the present embodiment, the fuel injection amount Q corresponds to the load of the diesel engine 1, and is calculated by referring to a map (not shown).

Further, at step 103, the ECU
51 calculates a corrected injection pressure Y based on the engine speed NE and the fuel injection amount Q calculated this time. Here, the corrected injection pressure Y corresponds to a pressure fluctuation value of fuel generated by pressure pulsation accompanying fuel injection or the like at the time of next injection, and a map as shown in FIG. 5 is taken into consideration. It is calculated by: This map shows the engine speed NE and the fuel injection amount Q corresponding to the engine load.
The correction injection pressure Y is determined empirically in advance.

The ECU 51 then proceeds to step 10
In step 4, a value obtained by adding the correction injection pressure Y calculated this time to the fuel pressure PC read this time is set as the injection fuel pressure PI.

Further, in the next step 105, the valve opening time TAU is calculated based on the fuel pressure PI during injection and the fuel injection amount Q calculated this time. Then step 1
In 06, when the predetermined injection timing has arrived, the ECU 51 controls the injector 2 based on the valve opening time TAU calculated this time, and once ends the subsequent processing.

Next, the operation and effect of this embodiment will be described. According to the present embodiment, the correction injection pressure Y is calculated based on the engine speed NE and the fuel injection amount Q corresponding to the engine load, and the fuel pressure during injection P is calculated based on the correction injection pressure Y.
I was determined, and was corrected by reflecting it in the valve opening time TAU. Therefore, pressure pulsation occurs inside the injection system due to the injection, and the pressure reflected wave generated at this time is
Even if a phenomenon synchronous with the injection period of the next injection cylinder occurs, the valve opening time TAU is controlled in consideration of the effect of the pressure reflected wave. Therefore, an optimal fuel amount can be secured for the operating state and the pressure pulsation state of the diesel engine 1 at that time. As a result, problems such as output fluctuation and deterioration of drivability due to the inability to obtain the expected fuel injection amount can be solved, and the controllability of fuel injection can be prevented from lowering.

According to the present embodiment, the above-described operation and effect can be achieved without providing a separate pressure pulsation preventing member, so that an increase in the number of parts and an increase in cost can be suppressed.

Further, since it is not necessary to provide a separate pressure pulsation preventing member in the injection system, the flow of fuel is not obstructed thereby. Therefore, it is possible to prevent a decrease in fuel pressure due to hindering a smooth flow of the fuel, and it is possible to reliably prevent a decrease in controllability due to the provision of a separate pressure pulsation prevention member.

In addition, according to the present embodiment, even if the pressure at the time of injection increases due to the pressure pulsation, the valve opening time TAU becomes shorter by that much, so that Fuel efficiency can also be improved.

In addition, according to the present embodiment, the fuel injection amount Q corresponding to the engine speed NE and the engine load
Based on the above, the correction injection pressure Y is calculated by a map empirically determined in advance. Therefore, the fuel pressure pulsation state at that time can be grasped simply and accurately. As a result, the amount of injected fuel can be further optimized.

(Second Embodiment) Next, a second embodiment of the present invention will be described with reference to FIG. However, in the configuration and the like of the present embodiment, the same members and the like as those in the above-described first embodiment are denoted by the same reference numerals, and description thereof will be omitted. The following description focuses on the differences from the first embodiment.

In the first embodiment, the valve opening time TA
U is controlled to control the amount of fuel to be injected. On the other hand, the present embodiment is characterized in that the target injection timing Ainj is controlled.

FIG. 6 is a flow chart showing an "injection timing control routine" executed by the ECU 51. This routine is executed by interruption every predetermined crank angle.

When the processing of this routine is started, the ECU
51, first, in step 201, various sensors and the like 2
Accelerator opening ACC based on signals from 1 to 30 etc.
P, engine speed NE, fuel pressure PC, etc. are read.

Next, at step 202, the ECU 5
1 calculates the fuel injection amount Q by referring to a map (not shown) based on the accelerator opening ACCP and the engine speed NE read this time.

Further, in step 203, the ECU
51 calculates a basic injection timing AinjB by referring to a map (not shown) based on the engine speed NE and the fuel injection amount Q calculated this time.

Subsequently, at step 204, the ECU
51 calculates a corrected injection pressure Y based on the engine speed NE and the fuel injection amount Q. This corrected injection pressure Y is calculated by referring to the map shown in FIG. 5, as in the first embodiment.

Then, in the next step 205,
Based on the correction injection pressure Y calculated this time, the correction injection timing K
Calculate Y. When calculating the correction injection timing KY, the correction injection pressure Y is converted into a timing by using a conversion coefficient empirically determined in advance.

Thereafter, the ECU 51 proceeds to step 20
In step 6, a value obtained by adding the correction injection timing KY calculated this time to the basic injection timing AinjB calculated this time is set as the final target injection timing Ainj. And
The ECU 51 once ends the subsequent processing.

As described above, in the present embodiment, the corrected injection pressure Y is calculated based on the engine speed NE and the fuel injection amount Q, and the corrected injection pressure Y is converted into the corrected injection timing KY. Then, the final target injection timing Ainj is corrected according to the corrected injection timing KY.
For this reason, even if a pressure pulsation occurs, the actual output can be adapted to the required output by correcting the fuel injection timing to the advance or retard side.
For this reason, it is possible to prevent a decrease in controllability without causing output fluctuation or the like.

Also in this embodiment, it is not necessary to use a new pressure pulsation prevention member separately.
The same operation and effect as those of the first embodiment are provided. Further, in the present embodiment, due to the pressure pulsation, the injection pressure is
Even if the required value is shifted, for example, to the increasing side, the injection timing is properly corrected, so that the premixed air ratio does not become too large. In other words, a deviation from the requirement of the premixed gas ratio due to the deviation of the injection pressure can be absorbed by correcting the injection timing. Therefore, it is possible to avoid a situation where the combustion noise is deteriorated.

(Third Embodiment) Next, a third embodiment of the present invention will be described with reference to FIGS. However, also in the configuration and the like of the present embodiment, the same members and the like as those in the above-described first embodiment are denoted by the same reference numerals, and description thereof is omitted. And, below, the first
The following description focuses on differences from the first embodiment.

In the first embodiment, the valve opening time TA
When controlling U, the correction injection pressure Y is calculated by referring to the map. On the other hand, the present embodiment is characterized in that the correction injection pressure Y is calculated by calculating the magnitude of the water hammer.

That is, FIG. 7 is a timing chart showing a water hammer component amount and the like which can be generated when the injector 2 is closed, which is one of the water hammer. As shown in the figure, the amount of the water hammer component generated when the injector 2 is closed is generated as a pressure wave that compresses at the moment when the fuel injection ends (X in the figure), and then attenuates while drawing a sine curve. Then, the amount of the water hammer component affects the next injection (Y in the figure). Here, the cycle (2 * ω) and the damping rate α of the pressure wave are determined by the specifications of the injection system (diameter and length of the pipe), the fuel temperature, and the like, and are referred to as the size of the peak of the water hammer component amount. Is determined by the valve opening time TAU, the fuel pressure PC, and the like.
Further, the attenuation rate is also determined by the specifications (diameter and length) of the injection tube. That is, if these values are grasped, it is possible to directly grasp how much the water hammer component amount has an effect on the next injection, unlike the map as in the first embodiment. If the pressure is taken as the pressure, the corrected injection pressure Y in the first embodiment can be recognized.

The following is a description of the processing for obtaining the corrected injection pressure Y by calculation taking these factors into account. That is, FIG. 8 is a flowchart illustrating the “correction injection pressure calculation routine” executed by the ECU 51. This routine is executed by interruption every predetermined crank angle.

When the processing of this routine is started, the ECU
51, first, in step 301, various sensors 2
1 to 30, etc., the fuel injection amount Q, the fuel pressure P
C, the engine speed NE, the valve opening time TAU, and the like are read.

Next, in step 302, the ECU 51 obtains the water hammer component amount X generated when the injector 2 was previously closed. That is, a value obtained by multiplying the fuel injection amount Q and the fuel pressure PC read this time by a predetermined coefficient k is set as the water hammer component amount X.

The ECU 51 also proceeds to step 303
, The time T from the previous valve closing time of the injector 2 to the intermediate time point of the valve opening time TAU in the current injection cylinder.
Is calculated. That is, the time T is 180 [° CA].
It is expressed as −１ ／ TAU [ms], and when converted to time, 1.08 * NE [ms] − ／ TAU [m
s].

Further, in step 304, the ECU 51 obtains the water hammer component β at the intermediate point. The water hammer component β at the intermediate point is β = α * sin (T · π /
ω).

Next, in step 305, the ECU 51 obtains the magnitude γ of the water hammer component amount Y in the current injection cylinder in the time direction. The magnitude γ in the time direction is γ = si
n (TAU · π / ω).

Thereafter, in step 306, the ECU 51 calculates the water hammer component amount Y. This water hammer component amount Y
Is represented by Y = β * γ * X. Here, if the water hammer component amount X generated at the time of the previous closing of the injector 2 is converted into an injection fuel pressure equivalent value, Y is equivalent to the corrected injection pressure Y in the first embodiment. Become. And
As described in the first embodiment, the injection fuel pressure PI is obtained based on the corrected injection pressure Y, and the correction is performed by reflecting the fuel pressure PI on the valve opening time TAU.

As described above, according to the present embodiment, the corrected injection pressure Y is calculated in consideration of the pressure wave component due to the closing of the injector 2. For this reason, the valve opening time T is considered after considering the pressure wave component that can greatly affect the pressure pulsation.
The AU and, consequently, the fuel amount to be injected are corrected, so that the fuel amount can be further optimized.

The present invention is not limited to the above-described embodiments, but may be implemented as follows by appropriately changing a part of the configuration without departing from the spirit of the invention. (1) In the third embodiment, only the pressure wave component due to the closing of the injector 2 is described. However, other pressure wave components (for example, the amount of the water hammer component when the pressure control valve 10 is closed, the common rail 4 May be taken into account. By taking such components into consideration, control accuracy can be further improved.

(2) The injector 2 does not necessarily have to have the configuration described in detail in the above embodiment. (3) In the first embodiment, the valve opening time TAU is corrected as the command value. However, the command value itself of the injection amount may be corrected.

(4) In the above embodiment, four cylinders
Although the present invention is embodied in the diesel engine 1 having 1 to $ 4, the number of cylinders is not limited at all if the engine has a plurality of cylinders. For example, the present invention can be embodied as having six or eight cylinders. Furthermore,
The present invention is not limited to the diesel engine 1 but can be applied to a gasoline engine.

(5) The injection control (valve opening time TAU) of the first embodiment and the injection timing control of the second embodiment may be performed simultaneously. With such a configuration, both effects can be achieved at the same time.

[0082]

As described in detail above, according to the present invention,
Prevention of deterioration in controllability of fuel injection without increasing cost in an injection control device for a pressure-accumulating multi-cylinder engine that injects high-pressure fuel accumulated in an accumulator pipe from a fuel injector to each cylinder of the engine. The effect is excellent.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing an injection control device for a pressure-accumulating multi-cylinder engine according to a first embodiment of the present invention.

FIG. 2 is a diagram showing a configuration of an injector, wherein (a)
FIG. 3 is a cross-sectional view showing a state in which the solenoid is not excited, FIG. 4B is a sectional view showing an invalid injection state, and FIG.

FIG. 3 is a block diagram showing an electrical configuration of an ECU.

FIG. 4 shows an “injection control routine” executed by the ECU.
5 is a flowchart showing the process.

FIG. 5 is a map showing a relationship between a corrected injection pressure with respect to an engine speed and a fuel injection amount.

FIG. 6 is a flowchart illustrating an “injection timing control routine” executed by an ECU according to the second embodiment;

FIG. 7 is a timing chart showing a change in a water hammer component amount and the like that may occur when the injector is closed.

FIG. 8 is a flowchart illustrating a “correction injection pressure calculation routine” executed by an ECU according to the third embodiment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Diesel engine as an internal combustion engine, 2 ... Injector as a fuel injection valve, 4 ... Common rail as a pressure accumulation pipe, 6 ... Supply pump, 21 ... Accelerator sensor, 27 ... Fuel pressure sensor, 28 ... NE sensor, 29 ... G sensor , 51... An electronic control unit (ECU).

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁶ Identification code FI F02M 51/00 F02M 51/00 E 51/06 51/06 Z

Claims (5)

[Claims] 1. A high pressure fuel is supplied from a supply pump, and a pressure accumulating pipe for accumulating the high pressure fuel, a fuel injection valve connected to the pressure accumulating pipe for injecting fuel into each cylinder of the engine, Operating state detecting means for detecting an operating state; and an injection control for obtaining a valve opening period of the fuel injection valve based on a detection result of the operating state detecting means, and controlling the fuel injection valve based on the valve opening period. A fuel pressure pulsation state detected by the pulsation state detection means, wherein the pulsation state detection means detects a fuel pressure pulsation state in the pressure accumulation pipe. And a valve-opening period correcting means for correcting the valve-opening period. 2. A high pressure fuel is supplied from a supply pump, and a pressure accumulating pipe for accumulating the high pressure fuel, a fuel injection valve connected to the pressure accumulating pipe for injecting fuel into each cylinder of the engine, and Operating state detecting means for detecting an operating state, an injection control means for obtaining an injection timing by the fuel injection valve based on a detection result of the operating state detecting means, and controlling the fuel injection valve based on the injection timing; In an injection control device for a pressure-accumulation type multi-cylinder engine, comprising: a pulsation state detection means for detecting a fuel pressure pulsation state in the pressure accumulation pipe; and a fuel pressure pulsation state detected by the pulsation state detection means. An injection control device for a pressure-accumulating multi-cylinder engine, comprising: injection timing correction means for correcting the injection timing. 3. A high pressure fuel is supplied from a supply pump, and a pressure accumulating pipe for accumulating the high pressure fuel; a fuel injection valve connected to the pressure accumulating pipe for injecting fuel into each cylinder of the engine; Operating state detecting means for detecting an operating state; and, based on a detection result of the operating state detecting means, an opening period of the fuel injection valve and an injection timing by the fuel injection valve are obtained. A pressure control type multi-cylinder engine having an injection control means for controlling a fuel injection valve on the basis of: a pulsation state detection means for detecting a fuel pressure pulsation state in the pressure accumulation pipe; and the pulsation state detection means. And a correction means for correcting the valve opening period and the injection timing in accordance with the fuel pressure pulsation state detected by the fuel injection pulsation state. 4. An injection control device for a pressure-accumulating multi-cylinder engine according to claim 1, wherein said pulsation state detecting means is empirically determined in advance in accordance with a load and a rotation speed of said engine at that time. A fuel pressure fluctuation state detected by the fuel pressure fluctuation state detected by the fuel pressure fluctuation state. 5. The injection control device for a pressure-accumulating multi-cylinder engine according to claim 1, wherein the pulsation state detecting means considers at least a pressure wave component caused by closing the fuel injection valve. An injection control device for a pressure-accumulating multi-cylinder engine, which detects a fuel pressure pulsation state.