Fuel supply system control device

Abstract

To prevent an unintended fuel rich state from occurring at the time of starting an internal combustion engine.SOLUTION: A combustion supply device 50 comprises a fuel injection valve 51, a delivery pipe 52, a relief passage 60, a first on-off valve 64, and a second on-off valve 65. The fuel injection valve 51 injects gaseous fuel. The delivery pipe 52 is a pipe for supplying gaseous fuel to the fuel injection valve 51. The relief passage 60 connects an intake passage 21 and the delivery pipe 52 of an internal combustion engine 10. The first on-off valve 64 can supply gaseous fuel in the delivery pipe 52 to the relief passage 60. The second on-off valve 65 is provided in the relief passage 60. The second on-off valve 65 opens when a pressure in a portion of the relief passage 60 on the intake passage 21 side relative to the second on-off valve 65 becomes lower by a predetermined specified pressure or more than a pressure in a portion of the relief passage 60 on the delivery pipe 52 side relative to the second on-off valve 65.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a control device for a fuel supply device.

Background Art

[0002] The fuel supply device described in Patent Document 1 includes a delivery pipe and a fuel injection valve. The fuel injection valve receives the supply of gaseous fuel through the delivery pipe. Further, the fuel supply device described in Patent Document 1 includes a relief pipe and a relief valve. The upstream end of the relief pipe is connected to the delivery pipe. The downstream end of the relief pipe is connected to the intake passage of the internal combustion engine. And, the relief valve is switched from the closed state to the open state when the pressure in the delivery pipe is higher than the allowable limit pressure at the start of the internal combustion engine. When the relief valve is in the open state, the gaseous fuel is discharged into the intake passage through the relief pipe, and as a result, the pressure in the delivery pipe decreases.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the technique described in Patent Document 1, when the pressure in the delivery pipe is high at the start of the internal combustion engine, a large amount of gaseous fuel flows into the intake passage. On the other hand, at the start of the internal combustion engine, the amount of intake air supplied to the internal combustion engine is relatively small. Therefore, in the technique described in Patent Document 1, there is a risk of unintentionally becoming a fuel-rich state at the start of the internal combustion engine.

Means for Solving the Problems

[0005] To solve the above problems, the present invention provides a fuel injection valve for injecting gaseous fuel, a delivery pipe for supplying the gaseous fuel to the fuel injection valve, and a relief passage connecting the intake passage of an internal combustion engine and the delivery pipe. The valve opens when the pressure inside the delivery pipe is equal to or greater than the specified pipe pressure. The system comprises a first on-off valve capable of supplying the gaseous fuel in the delivery pipe to the relief passage, and a second on-off valve provided in the relief passage. The relief passage has a vacuum tank on the delivery pipe side relative to the second on / off valve that supplies negative pressure to the vehicle's actuator. The second on-off valve is a fuel supply device that opens when the pressure in the relief passage on the intake passage side relative to the second on-off valve becomes lower than or equal to a predetermined specified pressure compared to the pressure in the relief passage on the delivery pipe side relative to the second on-off valve.

[0006] According to the above configuration, the second valve opens when the pressure in the portion of the relief passage on the intake passage side becomes sufficiently low relative to the second valve. When the pressure in the portion of the relief passage on the intake passage side is low, a considerable amount of intake air is supplied to the internal combustion engine. Therefore, even if the second valve opens and gaseous fuel flows into the intake passage, it is unlikely that the internal combustion engine will become excessively fuel-rich. [Brief explanation of the drawing]

[0007] [Figure 1] A schematic diagram of a vehicle equipped with an internal combustion engine and fuel supply system. [Modes for carrying out the invention]

[0008] Hereinafter, one embodiment of the fuel supply device will be described with reference to the drawings. <Overall Configuration of an Internal Combustion Engine> As shown in Figure 1, the vehicle 500 is equipped with an internal combustion engine 10. The internal combustion engine 10 uses a gaseous fuel, such as hydrogen, as fuel. The internal combustion engine 10 has a crankshaft 11, four cylinders 12, four pistons 13, four connecting rods 14, and four spark plugs 15. Note that in Figure 1, only one of the four sets of cylinders 12, pistons 13, connecting rods 14, and spark plugs 15 is illustrated.

[0009] Cylinder 12 is a space for burning a mixture of fuel and intake air. The piston 13 reciprocates within cylinder 12 as the mixture burns. The piston 13 is connected to the crankshaft 11 via a connecting rod 14. The connecting rod 14 transmits the reciprocating motion of the piston 13 as rotational motion of the crankshaft 11. The tip of the spark plug 15 is located inside cylinder 12. The spark plug 15 ignites the mixture inside cylinder 12.

[0010] As shown in Figure 1, the internal combustion engine 10 is equipped with an intake passage 21 and an exhaust passage 31. The intake passage 21 is the passage for intake air. The intake passage 21 is connected to each cylinder 12. The exhaust passage 31 is the passage for exhaust air. The exhaust passage 31 is connected to each cylinder 12.

[0011] The internal combustion engine 10 has a plurality of intake valves 21A and a plurality of exhaust valves 31A. Note that in Figure 1, only one of the plurality of intake valves 21A and only one of the plurality of exhaust valves 31A are shown. An intake valve 21A is provided for each cylinder 12. The intake valve 21A is located at the connection point between the intake passage 21 and the cylinder 12. When the intake valve 21A operates, the opening on the cylinder 12 side of the intake passage 21 is opened and closed. An exhaust valve 31A is provided for each cylinder 12. The exhaust valve 31A is located at the connection point between the exhaust passage 31 and the cylinder 12. When the exhaust valve 31A operates, the opening on the cylinder 12 side of the exhaust passage 31 is opened and closed.

[0012] The internal combustion engine 10 includes an intercooler 22, a throttle valve 23, and a surge tank 24. The intercooler 22 is located in the middle of the intake passage 21. The intercooler 22 cools the intake air. The throttle valve 23 is located downstream of the intercooler 22 in the intake passage 21. The throttle valve 23 has an adjustable opening. The throttle valve 23 adjusts the amount of intake air flowing into the cylinder 12 according to its opening. The surge tank 24 is located downstream of the throttle valve 23 in the intake passage 21. The surge tank 24 can store a certain volume of intake air.

[0013] Vehicle 500 has a supercharger 40. The supercharger 40 is installed across the intake passage 21 and the exhaust passage 31. The supercharger 40 has a compressor wheel 41, a turbine wheel 42, a bypass passage 43, and a wastegate valve 44. The compressor wheel 41 is located upstream of the intercooler 22 in the intake passage 21. The turbine wheel 42 is located in the middle of the exhaust passage 31. The turbine wheel 42 rotates in accordance with the exhaust flow. The compressor wheel 41 rotates together with the turbine wheel 42. The compressor wheel 41 compresses and sends out the intake air as it rotates. That is, the intake air is supercharged by the rotation of the compressor wheel 41. The bypass passage 43 connects the upstream and downstream portions of the exhaust passage 31 with respect to the turbine wheel 42. That is, the bypass passage 43 is a passage that bypasses the turbine wheel 42. The wastegate valve 44 is located at the downstream end of the bypass passage 43. The wastegate valve 44 is adjustable in its opening degree. Changing the opening degree of the wastegate valve 44 changes the amount of exhaust gas flowing through the bypass passage 43.

[0014] <Regarding the fuel supply system> As shown in Figure 1, the vehicle 500 is equipped with a fuel supply system 50. The fuel supply system 50 comprises four fuel injectors 51 and a delivery pipe 52. Note that only one of the four fuel injectors 51 is shown in Figure 1.

[0015] The fuel injector 51 injects gaseous fuel directly into the cylinder 12 without passing through the intake passage 21. In other words, the fuel injector 51 is a so-called in-cylinder injection valve. The delivery pipe 52 is a fuel flow passage for supplying gaseous fuel to the fuel injector 51. The delivery pipe 52 is connected to a fuel tank (not shown). In other words, the delivery pipe 52 receives gaseous fuel from the fuel tank.

[0016] The fuel supply device 50 is equipped with a relief passage 60. The relief passage 60 comprises a vacuum tank 61, a first relief passage 62, and a second relief passage 63. The inside of the vacuum tank 61 is at a lower pressure than atmospheric pressure. When the wastegate valve 44 is fully open, that is, when the internal combustion engine 10 is operating without supercharging, the air inside the vacuum tank 61 is drawn into the surge tank 24. In other words, the vacuum tank 61 accumulates the negative pressure in the surge tank 24 during non-supercharging operation.

[0017] The vacuum tank 61 supplies negative pressure to the actuators of the vehicle 500. Specifically, the vacuum tank 61 supplies negative pressure to the brake booster of the vehicle 500. Therefore, the vacuum tank 61 has a sufficient volume to operate the actuators of the vehicle 500 with negative pressure.

[0018] The first relief passage 62 connects the delivery pipe 52 and the vacuum tank 61. The second relief passage 63 connects the vacuum tank 61 and the surge tank 24. Therefore, the relief passage 60 as a whole connects the intake passage 21 and the delivery pipe 52 of the internal combustion engine 10. As a result, gaseous fuel in the delivery pipe 52 can flow into the surge tank 24 via the first relief passage 62, the vacuum tank 61, and the second relief passage 63.

[0019] The fuel supply device 50 includes a first on-off valve 64 and a second on-off valve 65. The first on-off valve 64 is located at the connection point of the delivery pipe 52 and the first relief passage 62. The first on-off valve 64 is an electronically controlled electromagnetic valve. The first on-off valve 64 is normally closed. The first on-off valve 64 can be electrically switched between open and closed states. When the first on-off valve 64 is open, the gaseous fuel in the delivery pipe 52 is supplied to the relief passage 60.

[0020] The second on-off valve 65 is provided in the relief passage 60. Specifically, the second on-off valve 65 is located in the middle of the second relief passage 63. The second on-off valve 65 is a one-way valve. The second on-off valve 65 allows only the flow from the vacuum tank 61 side to the surge tank 24 side in the second relief passage 63. Since the second on-off valve 65 is located in the middle of the second relief passage 63, the vacuum tank 61 is located on the delivery pipe 52 side with respect to the second on-off valve 65.

[0021] Although detailed illustration is omitted, the second on-off valve 65 has a body and a valve body capable of opening and closing the opening of the body. The valve body is pressed against the opening of the body by a spring. Due to the pressing force of this spring, the valve body closes the opening of the body. Also, when the difference between the downstream pressure and the upstream pressure with respect to the valve body exceeds the pressing force of the spring, the valve body opens.

[0022] That is, the second on-off valve 65 opens when the pressure of the portion of the relief passage 60 on the intake passage 21 side with respect to the second on-off valve 65 becomes lower than the pressure of the portion of the relief passage 60 on the delivery pipe 52 side with respect to the second on-off valve 65 by a specified pressure or more. Therefore, the specified pressure here is predetermined as a pressure difference capable of operating the valve body against the pressing force of the above-described spring.

[0023] <Regarding the control device> The vehicle 500 includes a pressure sensor 71 and a control device 72. The pressure sensor 71 is located inside the delivery pipe 52. The pressure sensor 71 detects the pipe pressure P inside the delivery pipe 52.

[0024] The control device 72 controls the first on-off valve 64. The control device 72 obtains a signal indicating the pipe pressure P from the pressure sensor 71. The control device 72 opens the first on-off valve 64 when the pipe pressure P is equal to or greater than the specified pipe pressure. The specified pipe pressure can be determined by testing or simulation, etc., as the pressure at which leakage of gaseous fuel from the fuel injection valve 51, etc., can be reduced to an acceptable level.

[0025] The control device 72 may be configured as a circuit including one or more processors that execute various processes according to a computer program (software). Alternatively, the control device 72 may be configured as a circuit including one or more dedicated hardware circuits, such as application-specific integrated circuits (ASICs), or a combination thereof, that execute at least some of the various processes. The processor includes a CPU and memory such as RAM and ROM. The memory stores program code or instructions configured to cause the CPU to execute processes. Memory, or computer-readable media, includes any available media accessible by a general-purpose or dedicated computer.

[0026] <Operation of this embodiment> When the pipe pressure P is equal to or greater than the specified pipe pressure, the control device 72 opens the first on-off valve 64. When the first on-off valve 64 opens, the gaseous fuel in the delivery pipe 52 is stored in the vacuum tank 61 through the first relief passage 62. As a result, the pipe pressure P decreases.

[0027] When the internal combustion engine 10 is stopped, the pressure in the surge tank 24 is approximately atmospheric pressure. Therefore, in the relief passage 60, the pressure on the intake passage 21 side is higher than the pressure on the delivery pipe 52 side relative to the second on-off valve 65. As a result, the second on-off valve 65 is closed. In other words, when the internal combustion engine 10 is stopped, the gaseous fuel that has flowed into the vacuum tank 61 from the delivery pipe 52 remains stored in the vacuum tank 61.

[0028] On the other hand, when the internal combustion engine 10 starts to operate, the pressure in the intake passage 21, including the surge tank 24, decreases as the piston 13 and intake valve 21A are driven. However, immediately after starting the internal combustion engine 10, the amount of intake air flowing through the intake passage 21 is small, so the pressure in the surge tank 24 does not decrease significantly. Therefore, even if the pressure in the surge tank 24 is lower than the pressure in the vacuum tank 61, the second on-off valve 65 remains closed as long as the difference is less than the specified pressure. Consequently, in this case, the gaseous fuel remains stored in the vacuum tank 61.

[0029] After the internal combustion engine 10 starts, let's assume that the amount of intake air to the internal combustion engine 10 increases while it is operating in an unsupercharged state. In this case, the pressure in the intake passage 21 drops considerably. Then, in the relief passage 60, when the pressure on the intake passage 21 side drops by a specified pressure or more relative to the second on-off valve 65, the second on-off valve 65 opens. As a result, the gaseous fuel that flows from the delivery pipe 52 into the vacuum tank 61 flows into the surge tank 24. The gaseous fuel that flows into the surge tank 24 is then guided to the cylinder 12 and used for combustion.

[0030] Let's assume that the internal combustion engine 10 is operating under supercharging conditions as the required torque increases. At this time, the pressure in the surge tank 24 is greater than atmospheric pressure. Therefore, in the relief passage 60, the pressure on the intake passage 21 side is higher than the pressure on the delivery pipe 52 side relative to the second on-off valve 65. As a result, the second on-off valve 65 is closed. In other words, when the internal combustion engine 10 is operating under supercharging conditions, even if gaseous fuel flows into the vacuum tank 61 from the delivery pipe 52, the gaseous fuel remains stored in the vacuum tank 61.

[0031] <Effects of this embodiment> (1) As described above, the second on-off valve 65 opens when the pressure in the portion of the relief passage 60 on the intake passage 21 side becomes sufficiently low relative to the second on-off valve 65. When the pressure in the portion of the relief passage 60 on the intake passage 21 side is low, a considerable amount of intake air is supplied to the internal combustion engine 10. Therefore, according to the above embodiment, even if the second on-off valve 65 opens and gaseous fuel flows into the surge tank 24, it is unlikely that the internal combustion engine 10 will become excessively fuel-rich.

[0032] (2) According to the above embodiment, the vacuum tank 61 can be used as the supply destination for the gaseous fuel from the first on-off valve 64. Since the vacuum tank 61 has a sufficient volume, even if gaseous fuel is supplied, there is little possibility that the pressure inside the vacuum tank 61 will fluctuate significantly. Also, because the volume of the vacuum tank 61 is large, when gaseous fuel is supplied from the first on-off valve 64, the concentration of the gaseous fuel decreases significantly. Therefore, even if air containing gaseous fuel is supplied from this vacuum tank 61 to the surge tank 24, the effect on the air-fuel ratio of the gaseous fuel is minimal.

[0033] (3) According to the above embodiment, the existing vacuum tank 61 used to supply negative pressure to the actuator is used as the destination for the gaseous fuel from the first on-off valve 64. As a result, there is no need to install a new, large-volume component as the destination for the gaseous fuel from the first on-off valve 64.

[0034] <Example of changes> This embodiment can be implemented with the following modifications. This embodiment and the following modifications can be combined with each other to the extent that they do not contradict each other technically.

[0035] In the above embodiment, the configuration of the vehicle 500 is not limited to the examples of the above embodiment. For example, the configuration of the supercharger 40 may be omitted in the vehicle 500. The vehicle 500 only needs to have at least the fuel supply device 50 and the configuration related to the combustion of the internal combustion engine 10.

[0036] In the above embodiment, the relief passage 60 can omit the vacuum tank 61. If the vacuum tank 61 is omitted, the relief passage 60 may be a single pipe without distinction between the first relief passage 62 and the second relief passage 63. Furthermore, the relief passage 60 may further include a tank or other configuration separate from the vacuum tank 61.

[0037] In the above embodiment, the first on-off valve 64 and the second on-off valve 65 may be solenoid valves or mechanical valves. At a minimum, the second on-off valve 65 should open when the pressure in the relief passage 60 on the intake passage 21 side relative to the second on-off valve 65 becomes lower than or equal to a specified pressure compared to the pressure in the delivery pipe 52 side relative to the second on-off valve 65. [Explanation of symbols]

[0038] 10... Internal combustion engine 21…Intake passage 50…Fuel supply device 51…Fuel injector 52…Delivery pipe 60…Relief corridor 61... Vacuum tank 64…First shut-off valve 65... Second shut-off valve 500...vehicles

Claims

[Claim 1] A fuel injector that injects gaseous fuel, A delivery pipe for supplying the gaseous fuel to the fuel injection valve, A relief passage connecting the intake passage of the internal combustion engine and the delivery pipe, A first on / off valve that opens when the pressure in the delivery pipe is equal to or greater than the specified pipe pressure, thereby supplying the gaseous fuel in the delivery pipe to the relief passage, A second on / off valve is provided in the relief passage, Equipped with, The relief passage has a vacuum tank on the delivery pipe side relative to the second on / off valve that supplies negative pressure to the vehicle's actuator. The second on-off valve opens when the pressure in the relief passage on the intake passage side relative to the second on-off valve becomes lower than or equal to a predetermined specified pressure compared to the pressure in the relief passage on the delivery pipe side relative to the second on-off valve. Fuel supply device.

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