JP3845898B2 - Engine fuel supply system - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to an improvement in an engine fuel supply apparatus.
[0002]
[Prior art]
2. Description of the Related Art As a fuel supply device provided in a conventional engine, there is an apparatus that includes an electromagnetic injector that injects fuel and performs duty control of the injector valve opening time (injection pulse width) between 0% and 100% depending on the operating state. (See Japanese Utility Model Publication No. 1-118158).
[0003]
A fuel supply device provided in a conventional direct injection engine includes a high-pressure fuel pump driven by the engine, a high-pressure fuel passage for supplying fuel sent from the high-pressure fuel pump to an injector, and a pressure for adjusting the fuel pressure in the high-pressure fuel passage. The fuel pressure is composed of a regulator and the like, and the fuel pressure guided to the injector is adjusted through the pressure regulator so that the differential pressure from the atmospheric pressure becomes constant.
[0004]
[Problems to be solved by the invention]
By the way, since the fuel flowing through the high pressure fuel passage is heated and expanded by the residual heat during the operation of the engine, the pressure in the high pressure fuel passage decreases as the fuel in the high pressure fuel passage contracts after the engine stops.
[0005]
However, in a direct-injection engine, if the fuel pressure in the high-pressure fuel passage decreases when the engine is started, the fuel pressure in the high-pressure fuel passage rises to a predetermined value even when the high-pressure fuel pump is activated due to engine cranking. It takes time to do so, and the fuel injection pressure of the injector cannot be obtained sufficiently, and the startability is impaired.
[0006]
In addition, it is conceivable to use an electric fuel pump to drive the high-pressure fuel passage in advance at the start of the engine so as to boost the pressure of the high-pressure fuel passage. There is a problem in that the driving efficiency is greatly reduced and the fuel consumption of the engine is deteriorated.
[0007]
The present invention has been made in view of the above problems, and an object of the present invention is to ensure startability in an engine fuel supply apparatus.
[0008]
[Means for Solving the Problems]
As shown in FIG. 5, the engine fuel supply device according to claim 1 is sent from an injector 107 that injects and supplies fuel to the engine, a high-pressure fuel pump 105 that is directly driven by the engine, and a high-pressure fuel pump 105. A high-pressure fuel passage 106 for supplying fuel to the injector 107, a pressure regulator 108 for adjusting the fuel pressure in the high-pressure fuel passage 106, an accumulator tank 111 that is connected to the high-pressure fuel passage 106 and stores pressurized fuel, and an accumulator tank 111; the accumulation passage switching valve 110 for opening and closing the accumulation passage connecting the high pressure fuel passage 106, before the cranking is performed at the start of the engine, and communicating the accumulator tank 111 and the high pressure fuel passage 106 through the accumulator passage switching valve 110 The high pressure fuel stored in the pressure storage tank 111 is stored in the high pressure fuel passage 106 after being introduced. And boosting means 120 at the time of starting to block the communication between the tank 111 and the high-pressure fuel passage 106 communicates between the accumulator tank 111 and the high pressure fuel passage 106 through the accumulator passage switching valve 110 during deceleration of the engine, before stopping of the engine The pressure accumulating tank 111 is provided with a pressure accumulating means 130 for blocking communication between the pressure accumulating tank 111 and the high pressure fuel passage 106 via the pressure accumulating passage switching valve 110.
[0009]
The fuel supply device for an engine according to claim 2 is the invention according to claim 1,
The engine is provided with a start delay means for delaying cranking until the pressure accumulation tank and the high pressure fuel passage communicate with each other via the pressure accumulation passage switching valve when the engine is started.
[0011]
According to a third aspect of the present invention, there is provided a fuel supply device for an engine according to the first or second aspect of the invention, wherein the engine is operated until the communication between the pressure accumulation tank and the high pressure fuel passage is cut off via the pressure accumulation passage switching valve when the engine is stopped. A stop postponing means for postponing the stop is provided.
[0013]
[Action]
2. The fuel supply device for an engine according to claim 1, wherein the pressure accumulation tank 111 and the high pressure fuel passage 106 are communicated with each other via the pressure accumulation passage switching valve 110 before the cranking is performed when the engine is started, and the pressure of the high pressure fuel passage 106 is increased. To do.
[0014]
Even when the pressure of the high-pressure fuel passage 106 decreases while the engine is stopped, the fuel injection pressure of the injector 107 can be sufficiently obtained by connecting the accumulator tank 111 to the high-pressure fuel passage 106 before cranking is performed. Startability can be secured.
[0015]
Before the engine is stopped, the communication between the pressure accumulation tank 111 and the high pressure fuel passage 106 is cut off via the pressure accumulation passage switching valve 110, and the fuel pressure in the pressure accumulation tank 111 can be reliably increased in preparation for the next start.
In addition, before cranking is performed when the engine is started, the accumulator tank is connected after the accumulator tank and the high-pressure fuel passage are connected via the accumulator passage valve and the high-pressure fuel stored in the accumulator tank is introduced into the high-pressure fuel passage. The pressure of the high pressure fuel passage is increased by cutting off the communication between the high pressure fuel passage and the high pressure fuel passage.
After introducing the fuel pressure of the accumulator tank and increasing the pressure of the high-pressure fuel passage, before the cranking is performed, the communication between the accumulator tank and the high-pressure fuel passage is shut off via the accumulator passage valve, The volume of the passage connecting the injectors is reduced, and the pressure of the high-pressure fuel passage is quickly increased by the fuel discharged from the high-pressure fuel pump. In this way, the fuel injection pressure of the injector at the start is further increased, and the startability is improved.
Further, when the engine is decelerated, the pressure accumulation tank and the high pressure fuel passage are communicated via the pressure accumulation passage switching valve, and the communication between the pressure accumulation tank and the high pressure fuel passage is blocked via the pressure accumulation passage switching valve before the engine is stopped.
When the engine decelerates, the amount of fuel injected from the injector decreases, and surplus fuel discharged from the high-pressure fuel pump into the high-pressure fuel passage increases. However, it can be avoided that the fuel injection from the injector is hindered.
[0016]
3. The fuel supply device for an engine according to claim 2, wherein the cranking is delayed until the accumulator tank and the high-pressure fuel passage are communicated with each other via the accumulator switching valve at the time of starting the engine. The pressure of the high pressure fuel passage can be reliably increased.
[0019]
4. The engine fuel supply device according to claim 3 , wherein the engine stoppage is postponed until the next start-up until the communication between the pressure accumulation tank and the high pressure fuel passage is cut off via the pressure accumulation passage switching valve when the engine is stopped. The fuel pressure in the accumulator tank can be reliably increased.
[0022]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.
[0023]
In FIG. 1, reference numeral 7 denotes four injectors facing each cylinder of the direct injection engine, and fuel is directly injected from each injector 7 into each cylinder.
[0024]
The injector 7 is duty-controlled when the injection pulse width (valve opening time) is 0 to 100%, and is opened by a pulse signal sent from the control unit.
[0025]
The engine compresses an air-fuel mixture formed by air sucked into the cylinder and fuel injected from the injector 7 with a piston and ignites and burns with an ignition plug.
[0026]
The fuel stored in the fuel tank 1 is sucked up through the low pressure fuel pump 2 and sent to the high pressure fuel pump 5 through the low pressure fuel passage 3. The fuel pressure in the low-pressure fuel passage 3 is adjusted via the pressure regulator 4 so that the pressure difference from the atmospheric pressure becomes a predetermined value.
[0027]
The high-pressure fuel pump 5 sends pressurized fuel to the high-pressure fuel passage 6 and is distributed from the high-pressure fuel passage 6 to the injectors 7 of each cylinder.
[0028]
The high pressure fuel pump 5 is directly driven by the engine. That is, the rotational force of the crankshaft of the engine is transmitted to the pump drive shaft of the high-pressure fuel pump 5 via the belt and pulley.
[0029]
The fuel pressure in the high-pressure fuel passage 6 is adjusted via the pressure regulator 8 so that the differential pressure from the atmospheric pressure becomes a predetermined value. Excess fuel sent from the high-pressure fuel pump 5 to the high-pressure fuel passage 6 is returned from the pressure regulator 8 to the fuel tank 1 through the fuel return passage 9. The pressure regulator 8 is disposed in the upper part of the high-pressure fuel passage 6 so that air contained in the fuel is discharged via the pressure regulator 8.
[0030]
During engine operation, the fuel pressure in the high-pressure fuel passage 6 is adjusted to be substantially constant, and the required amount of fuel is injected into each cylinder by duty-controlling the injection pulse width of each injector 7.
[0031]
By the way, if the fuel pressure in the high-pressure fuel passage 6 is reduced when the engine is started, the fuel pressure in the high-pressure fuel passage 6 rises to a predetermined value even if the high-pressure fuel pump 5 is operated due to cranking of the engine. It takes a long time, and the fuel injection pressure of the injector 7 relative to the pressure in the cylinder cannot be obtained sufficiently, so that the startability is impaired.
[0032]
In the present invention, the pressure accumulation tank 11 is connected to the high pressure fuel passage 6 through the pressure accumulation passage switching valve 10 and communicates with the high pressure fuel passage 6 before cranking is performed at the start. Thus, a sufficient fuel injection pressure of the injector 7 with respect to the pressure in the cylinder is obtained.
[0033]
The pressure accumulating tank 11 has a function of accumulating fuel whose pressure has been increased to a predetermined value, and the pressure in the high pressure fuel passage 6 is opened by opening the pressure accumulating passage switching valve 10 from a state in which the fuel pressure in the high pressure fuel passage 6 is reduced at the time of starting. Can be increased to a predetermined value.
[0034]
The electromagnetic pressure accumulation passage switching valve 10 has an open position for communicating the pressure accumulation tank 11 and the high pressure fuel passage 6 and a closed position for blocking communication between the pressure accumulation tank 11 and the high pressure fuel passage 6. An excitation current is sent from the valve drive means 12 to the pressure accumulation passage switching valve 10 by a signal sent from the control unit 13 so as to open and close.
[0035]
The control unit 13 inputs an intake air amount detected by the air flow meter 16, a signal such as a crank angle detected by the crank angle sensor 15, an ignition switch signal, a starter switch signal, and the like, and the pressure accumulation passage switching valve 10 and the injector 7. And the operation of a starter motor and a spark plug (not shown).
[0036]
The control unit 13 communicates the pressure accumulation tank 11 and the high pressure fuel passage 6 via the pressure accumulation passage switching valve 10 before cranking at the time of starting the engine, and increases the fuel pressure in the high pressure fuel passage 6. Cranking is postponed until the pressure accumulation passage switching valve 10 is switched to an open position where the pressure accumulation tank 11 and the high pressure fuel passage 6 communicate with each other when the engine is started.
[0037]
Further, the control unit 13 blocks communication between the pressure accumulation tank 11 and the high pressure fuel passage 6 via the pressure accumulation passage switching valve 10 before the engine is stopped, and accumulates pressure in the pressure accumulation tank 11. When the engine is stopped, the engine operation is suspended until the engine is switched to the closed position where the communication between the pressure accumulation tank 11 and the high pressure fuel passage 6 is switched off via the pressure accumulation passage switching valve 10.
[0038]
The flowchart of FIG. 2 shows a program for controlling the operation of the pressure accumulation passage switching valve 10 and the like, and this is executed at regular intervals.
[0039]
This will be described. First, in Step 1, it is determined whether or not the engine has been requested for starting before cranking has been performed in a state where an engine start request has been issued.
[0040]
If it is determined that the engine has not been started yet, the operation proceeds to Step 2 to postpone the operation of the starter motor.
[0041]
Subsequently, the process proceeds to Step 3, the pressure accumulation passage switching valve 10 is switched to the open position, and the pressure accumulation tank 11 is communicated with the high pressure fuel passage 6. As a result, the high-pressure fuel stored in the accumulator tank 11 in advance at the start is introduced into the high-pressure fuel passage 6 via the accumulator passage switching valve 10.
[0042]
The processing performed in Step 2 and Step 3 constitutes a boosting means at start-up.
[0043]
Subsequently, at Step 4, it is determined whether or not a predetermined time (for example, 0.2 seconds) has elapsed since the pressure accumulation passage switching valve 10 was switched to the open position.
[0044]
When a predetermined time has elapsed since the pressure accumulation passage switching valve 10 was switched to the open position, the process proceeds to Step 5 to release the operation postponement of the starter motor. Thus, the operation of switching the pressure accumulation passage switching valve 10 to the open position is terminated while the engine start is postponed, and the high pressure fuel stored in the pressure accumulation tank 11 is introduced into the high pressure fuel passage 6 via the pressure accumulation passage switching valve 10. Is done.
[0045]
The processing performed in Step 2 to Step 5 constitutes start delaying means for delaying cranking at the start.
[0046]
Subsequently, the process proceeds to Step 6 where the starter motor is operated to crank the engine, the fuel is injected from each injector 7, and ignited and burned by the spark plug, so that the engine is started. .
[0047]
Even when the pressure of the high-pressure fuel passage 6 decreases while the engine is stopped, the fuel injection pressure of the injector 7 can be sufficiently obtained by connecting the accumulator tank 11 to the high-pressure fuel passage 6 before cranking is performed. Startability can be secured.
[0048]
Since the pressure accumulation tank 11 communicates with the high-pressure fuel passage 6 during engine operation, the pressure fluctuation in the high-pressure fuel passage 6 is suppressed, and the fuel injection amount from each injector 7 can be accurately adjusted.
[0049]
On the other hand, when it is determined at Step 1 that the engine has already been cranked, the process proceeds to Step 7 to determine whether a request for stopping the engine operation has been issued.
[0050]
When the engine stop request has been issued, the process proceeds to Step 8 to postpone the engine stop.
[0051]
Subsequently, the process proceeds to Step 9 where the pressure accumulation passage switching valve 10 is switched to a closed position where the communication between the pressure accumulation tank 11 and the high pressure fuel passage 6 is blocked.
[0052]
The processing performed in Step 8 and Step 9 constitutes pressure accumulating means.
[0053]
Subsequently, in Step 10, it is determined whether or not a predetermined time (for example, 0.2 seconds) has elapsed.
[0054]
When a predetermined time has elapsed since the engine stop request was issued, the process proceeds to Step 11 where the fuel injection from each injector 7 is stopped and the operation of the spark plug is stopped. Thereby, this routine is completed.
[0055]
The processing performed in Step 8 to Step 10 constitutes a stop postponing means for postponing the engine stoppage.
[0056]
Thus, while the operation stoppage of the engine is postponed, the operation of switching the pressure accumulation passage switching valve 10 to the closed position is performed, and the communication between the pressure accumulation tank 11 and the high pressure fuel passage 6 is shut off. Thereby, fuel of a predetermined pressure is stored in the pressure accumulation tank 11 in preparation for the next start.
[0057]
In addition, since the time for delaying the start or stop of the engine is set to about 0.2 seconds, the driver does not feel uncomfortable.
[0058]
Next, as another embodiment, the control unit 13 blocks communication between the pressure accumulation tank 11 and the high pressure fuel passage 6 via the pressure accumulation passage switching valve 10 before cranking is performed.
[0059]
Further, when the engine is decelerated, the pressure accumulation tank 11 and the high pressure fuel passage 6 are communicated with each other via the pressure accumulation passage switching valve 10 to increase the fuel pressure in the pressure accumulation tank 11.
[0060]
The flowchart of FIG. 3 shows a program for controlling the operation of the pressure accumulation passage switching valve 10 and the like, and this is executed at regular intervals.
[0061]
This will be described. First, in Step 21, it is determined whether or not the engine has not been cranked yet in a state where an engine start request has been issued.
[0062]
If it is determined that the engine has not been started yet, the operation proceeds to Step 22 to postpone the operation of the starter motor.
[0063]
Then, it progresses to Step23, the pressure accumulation passage switching valve 10 is switched to an open position, and the pressure accumulation tank 11 is connected to the high pressure fuel passage 6. As a result, the high-pressure fuel stored in the accumulator tank 11 in advance at the start is introduced into the high-pressure fuel passage 6 via the accumulator passage switching valve 10.
[0064]
Subsequently, in Step 24, it is determined whether or not a predetermined time (for example, 0.2 seconds) has elapsed since the pressure accumulation passage switching valve 10 was switched to the open position.
[0065]
When a predetermined time has elapsed since the pressure accumulation passage switching valve 10 was switched to the open position, the process proceeds to Step 25, where the pressure accumulation passage switching valve 10 is switched to the closed position where communication between the pressure accumulation tank 11 and the high pressure fuel passage 6 is blocked.
[0066]
The processing performed in Step 24 and Step 25 constitutes a rolling stock rolling means.
[0067]
Then, it progresses to Step26 and cancels | releases the operation postponement of the said starter motor. Thus, the operation of switching the pressure accumulation passage switching valve 10 to the open position is terminated while the engine start is postponed, and the high pressure fuel stored in the pressure accumulation tank 11 is introduced into the high pressure fuel passage 6 via the pressure accumulation passage switching valve 10. Is done.
[0068]
Subsequently, the routine proceeds to Step 27, where the starter motor is operated to crank the engine, the fuel is injected from each injector 7, and is ignited and burned by the spark plug to start the engine. .
[0069]
Even when the pressure in the high-pressure fuel passage 6 decreases while the engine is stopped, the pressure accumulation tank 11 is connected to the high-pressure fuel passage 6 to increase the pressure of the high-pressure fuel passage 6 before cranking is performed. By closing the pressure accumulation passage switching valve 10 after cranking is performed after the fuel pressure in the pressure accumulation tank 11 is introduced to increase the pressure of the high pressure fuel passage 6, the passage volume connecting the high pressure fuel pump 5 and each injector 7 is reduced. The pressure is reduced and the pressure of the high-pressure fuel passage 6 is quickly increased by the fuel discharged from the high-pressure fuel pump 5. Thus, the startability is improved by further increasing the fuel injection pressure of the injector 7.
[0070]
On the other hand, if it is determined in Step 21 that the engine has already been cranked, the process proceeds to Step 28, where it is determined whether or not the predetermined deceleration region is set based on the map shown in FIG.
[0071]
When it is determined that the pressure is not in the predetermined deceleration region, the process proceeds to Step 30 to switch the pressure accumulation passage switching valve 10 to a closed position where the communication between the pressure accumulation tank 11 and the high pressure fuel passage 6 is blocked.
[0072]
When it is determined that the vehicle is in the predetermined deceleration region, the process proceeds to Step 29 where the pressure accumulation passage switching valve 10 is switched to an open position where the pressure accumulation tank 11 and the high pressure fuel passage 6 are communicated.
[0073]
The processing performed in Step 28 and Step 29 constitutes a pressure accumulating means during deceleration.
[0074]
Thus, while the engine is decelerating, the pressure accumulation passage switching valve 10 is opened and the fuel pressure in the high pressure fuel passage 6 is introduced into the pressure accumulation tank 11. During this deceleration, the amount of fuel injected from the injector 7 decreases and surplus fuel discharged from the high-pressure fuel pump 5 to the high-pressure fuel passage 6 increases, so that even if fuel is introduced from the high-pressure fuel passage 6 to the pressure accumulation tank 11 avoids be adversely impaired supporting the fuel injection from the injector 7.
[0075]
【The invention's effect】
As described above, according to the engine fuel supply device of the first aspect, even when the pressure of the high pressure fuel passage is reduced while the engine is stopped, the pressure accumulation tank is changed to the high pressure fuel passage before cranking is performed. By communicating, the fuel injection pressure of the injector can be sufficiently obtained and startability can be ensured.
In addition, after introducing the fuel pressure of the accumulator tank to boost the high-pressure fuel passage, before the cranking is performed, the communication between the accumulator tank and the high-pressure fuel passage is shut off via the accumulator passage valve. The volume of the passage connecting each of the injectors is reduced, and the fuel injection pressure at the time of start-up is further increased by the fuel discharged from the high-pressure fuel pump, thereby improving the startability.
Furthermore, since the accumulator tank and the high-pressure fuel passage communicate with each other through the accumulator passage switching valve when the engine decelerates, even if fuel is introduced from the high-pressure fuel passage into the accumulator tank, the fuel injection from the injector is hindered. Can be avoided.
[0076]
According to the fuel supply device for an engine according to claim 2, the cranking is postponed until the accumulator tank and the high-pressure fuel passage are communicated with each other via the accumulator switching valve when the engine is started. Thus, the pressure of the high pressure fuel passage can be reliably increased.
[0078]
According to the fuel supply device for an engine according to claim 3 , the engine stoppage is postponed until the communication between the pressure accumulation tank and the high pressure fuel passage is interrupted via the pressure accumulation passage switching valve when the engine is stopped. In preparation for the occasion, fuel of a predetermined pressure is reliably stored in the pressure accumulating tank.
[Brief description of the drawings]
FIG. 1 is a system diagram of a fuel supply system showing an embodiment of the present invention.
FIG. 2 is a flowchart showing the same control content.
FIG. 3 is a flowchart showing the contents of control in another embodiment.
FIG. 4 is a deceleration area determination diagram.
FIG. 5 is a claim correspondence diagram showing the invention according to claim 1;
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Fuel tank 2 Low pressure fuel pump 4 Pressure regulator 5 High pressure fuel pump 6 High pressure fuel passage 7 Injector 8 Pressure regulator 9 Fuel return passage 10 Accumulation passage changeover valve 11 Accumulation tank 12 Valve drive means 13 Control unit 105 High pressure fuel pump 106 High pressure fuel passage 107 Injector 108 Pressure Regulator 110 Pressure Accumulation Passage Switching Valve 111 Pressure Accumulation Tank 120 Pressure Boosting Means 121 Pressure Accumulation Means

Claims (3)

An injector that injects fuel into the engine;
A high-pressure fuel pump driven directly by the engine;
A high-pressure fuel passage for supplying fuel sent from the high-pressure fuel pump to the injector;
A pressure regulator for adjusting the fuel pressure in the high-pressure fuel passage;
An accumulator tank connected to the high pressure fuel passage to store pressurized fuel;
A pressure accumulation passage switching valve for opening and closing a pressure accumulation passage connecting the pressure accumulation tank and the high pressure fuel passage;
Before cranking is performed at the start of the engine, the accumulator tank and a high pressure high pressure fuel stored in the accumulator tank and communicating the accumulator tank and the high-pressure fuel passage via the accumulation passage switching valve from being introduced into the high-pressure fuel passage A boosting means at the time of starting to cut off the communication of the fuel passage ;
A pressure accumulating means for communicating the pressure accumulating tank and the high pressure fuel passage via the pressure accumulating passage switching valve at the time of deceleration of the engine, and shutting off the communication of the pressure accumulating tank and the high pressure fuel passage via the pressure accumulating passage switching valve before the engine stops;
An engine fuel supply apparatus comprising: 2. The engine fuel supply device according to claim 1, further comprising start delaying means for delaying cranking until the accumulator tank and the high pressure fuel passage communicate with each other through the accumulator switching valve at the start of the engine. According to claim 1 or 2, characterized in that it comprises a stop postponing means for postponing the shutdown of the engine to the communication of the accumulator tank and the high pressure fuel passage is cut off through the accumulation passage switching valve when stopping the engine Engine fuel supply device.

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