vehicle

Abstract

This ensures that the frequency of abnormal detection of the sub-fuel pump is maintained without causing any discomfort to the driver. [Solution] The invention includes an engine having a port injection valve, a low-pressure pipe that communicates with first and second branch pipes from which pressurized fuel is discharged by a main fuel pump and a sub-fuel pump, respectively, located in a fuel tank, and supplies fuel to the port injection valve, a control unit that switches between a first drive state in which the main fuel pump is driven and the sub-fuel pump is stopped, or a second drive state in which both the main fuel pump and the sub-fuel pump are driven, according to the engine's required output, and a diagnostic unit that forcibly drives the sub-fuel pump to diagnose an abnormality when an abnormality diagnosis condition is met in the first drive state, where the fuel pressure supplied to the port injection valve is above a predetermined value, wherein the diagnostic unit controls the sub-fuel pump to a rotational speed at which it cannot discharge fuel to the second branch pipe if the fuel pressure supplied to the port injection valve in the first drive state is above the predetermined value, and the diagnostic unit controls the sub-fuel pump to a rotational speed at which it cannot discharge fuel to the second branch pipe.

Description

Technical Field

[0001] The present invention relates to a vehicle.

Background Art

[0002] There are a main fuel pump and a sub - fuel pump provided in a fuel tank of a vehicle, which pressurize the fuel in the fuel tank and supply it to an engine. When the required output of the engine is low, only the main fuel pump is driven, and when the required output is high, both the main fuel pump and the sub - fuel pump are driven (see, for example, Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Abnormal diagnosis of a pump may be performed based on a voltage value or a current value applied during driving of the pump. When the required output of the engine is low, the sub - fuel pump is not driven. Therefore, there is a possibility that the execution frequency of abnormal diagnosis of the sub - fuel pump decreases. Also, such abnormal diagnosis is preferably performed without giving a sense of discomfort to the driver.

[0005] Therefore, an object of the present invention is to provide a vehicle in which the execution frequency of abnormal diagnosis of a sub - fuel pump is ensured without giving a sense of discomfort to the driver.

Means for Solving the Problems

[0006] The above objective is to provide an engine having port injection valves, a main fuel pump and a sub-fuel pump provided in a fuel tank, first and second branch pipes from which pressurized fuel from the main fuel pump and the sub-fuel pump, respectively, a low-pressure pipe communicating with the first and second branch pipes and supplying fuel to the port injection valves, and a control device that controls the main fuel pump and the sub-fuel pump, wherein the control device operates in a first operating state in which the main fuel pump is driven and the sub-fuel pump is stopped, or the main fuel pump The system includes a control unit that switches to a second drive state in which both the and sub-fuel pumps are driven, and a diagnostic unit that, when abnormality diagnosis conditions are met, including the fuel pressure supplied to the port injection valve in the first drive state being greater than or equal to a predetermined value, forcibly drives the sub-fuel pump and performs an abnormality diagnosis of the sub-fuel pump, wherein the diagnostic unit controls the rotational speed of the sub-fuel pump during forced drive to a rotational speed in which fuel cannot be discharged from the sub-fuel pump to the second branch pipe when the fuel pressure supplied to the port injection valve in the first drive state is greater than or equal to the predetermined value, which can be achieved by the vehicle.

[0007] The aforementioned abnormality diagnosis conditions may include the vehicle speed being equal to or greater than a predetermined speed.

[0008] The aforementioned abnormality diagnosis conditions may include the fact that the abnormality diagnosis has not been performed during the current trip.

[0009] The engine may have an in-cylinder injection valve and a high-pressure fuel pump that further pressurizes the fuel pressurized by the main fuel pump and sub-fuel pump and supplies it to the in-cylinder injection valve. [Effects of the Invention]

[0010] According to the present invention, it is possible to provide a vehicle in which the frequency of abnormality diagnosis of the sub-fuel pump is ensured without causing discomfort to the driver. [Brief explanation of the drawing]

[0011] [Figure 1]Figure 1 is a schematic diagram of a hybrid vehicle. [Figure 2] Figure 2 is a schematic diagram of the fuel supply system. [Figure 3] Figure 3 is a flowchart illustrating the sub-fuel pump malfunction diagnosis control. [Figure 4] Figures 4A and 4B illustrate the differences in fuel discharge conditions depending on the rotational speed when the sub-fuel pump is forcibly driven. [Modes for carrying out the invention]

[0012] [Overall configuration of a hybrid vehicle] Figure 1 is a schematic diagram of the hybrid vehicle 1. The hybrid vehicle 1 is equipped with an engine 10 and a motor 15 as the power source for driving. The engine 10 is an inline 4-cylinder gasoline engine, but is not limited to 4 cylinders; it may be a V-type engine or a diesel engine. A transmission unit 11 is provided in the power transmission path from the engine 10 to the drive wheels 13. The transmission unit 11 and the left and right drive wheels 13 are driven together via a differential 12.

[0013] The transmission unit 11 is equipped with a K0 clutch 14 and a motor 15. The motor 15 is located on the power transmission path from the engine 10 to the drive wheels 13.

[0014] The K0 clutch 14 is located between the engine 10 and the motor 15 in the power transmission path. The K0 clutch 14 engages when hydraulic pressure is supplied, connecting the power transmission between the engine 10 and the motor 15. The K0 clutch 14 disengages when the hydraulic pressure supply is stopped, interrupting the power transmission between the engine 10 and the motor 15. The K0 clutch 14 also slips from the start of torque transmission until it is fully engaged.

[0015] The motor 15 is connected to the battery 16 via an inverter 17. The battery 16 is a rechargeable secondary battery such as a nickel-metal hydride battery or a lithium-ion battery. The motor 15 functions as a motor that generates driving force for the vehicle in response to power supplied from the battery 16. Furthermore, the motor 15 also functions as a generator that generates electricity to charge the battery 16 in response to power transmission from the engine 10 and the drive wheels 13. The power exchanged between the motor 15 and the battery 16 is regulated by the inverter 17.

[0016] The transmission unit 11 is equipped with a torque converter 18 and an automatic transmission 19. The torque converter 18 is a fluid coupling with a torque amplification function. The automatic transmission 19 is a multi-stage transmission that switches the gear ratio in multiple stages. The torque converter 18 is installed between the motor 15 and the drive wheels 13 on the power transmission path. The automatic transmission 19 is installed between the torque converter 18 and the drive wheels 13 on the power transmission path. The torque converter 18 is equipped with a lock-up clutch (hereinafter referred to as LU clutch) 20 that receives hydraulic pressure, engages with it to directly connect the motor 15 and the automatic transmission 19.

[0017] The LU clutch 20 engages when hydraulic pressure is supplied, connecting the power transmission between the motor 15 and the drive wheels 13. The LU clutch 20 disengages when the hydraulic pressure supply is stopped. The LU clutch 20 also slips from disengagement until it engages again.

[0018] The transmission unit 11 is further equipped with an oil pump 21 and a hydraulic control mechanism 22. The hydraulic pressure generated by the oil pump 21 is supplied to the K0 clutch 14, torque converter 18, automatic transmission 19, and LU clutch 20 via the hydraulic control mechanism 22. The hydraulic control mechanism 22 is equipped with hydraulic circuits for the K0 clutch 14, torque converter 18, automatic transmission 19, and LU clutch 20, as well as various hydraulic control valves for controlling their operating hydraulic pressures.

[0019] The hybrid vehicle 1 is provided with an ECU (Electronic Control Unit) 100 as a control device for the hybrid vehicle. The ECU 100 is an electronic control unit including an arithmetic processing circuit that performs various arithmetic processes related to the running control of the vehicle, and a memory in which control programs and data are stored. The ECU 100 is an example of a control device, and specifically, functionally realizes a control unit and a diagnosis unit, which will be described later in detail.

[0020] An ignition switch 61, a crank angle sensor 62, and an air flow meter 63 are connected to the ECU 100. The ignition switch 61 detects the on / off state of the ignition. The crank angle sensor 62 detects the rotational speed of the crankshaft of the engine 10. The air flow meter 63 detects the amount of intake air introduced into the engine 10.

[0021] The ECU 100 controls the driving of the engine 10 and the motor 15. Specifically, the ECU 100 controls the inverter 17 to adjust the amount of power transfer between the motor 15 and the battery 16, thereby performing torque control of the motor 15. The ECU 100 performs drive control of the K0 clutch 14, the LU clutch 20, and the automatic transmission 19 through the control of the hydraulic control mechanism 22.

[0022] The ECU 100 runs the hybrid vehicle 1 in either the motor running mode or the hybrid running mode. In the motor running mode, the ECU 100 releases the K0 clutch 14 and rotates the drive wheels 13 with the power of the motor 15. In the hybrid running mode, the ECU 100 engages the K0 clutch 14 and rotates the drive wheels 13 with the power of at least one of the engine 10 and the motor 15. For example, when the required driving force for the hybrid vehicle 1 becomes equal to or greater than the driving force threshold value, the mode is switched from the motor running mode to the hybrid running mode. Also, when the charge amount of the battery 16 becomes equal to or less than the power threshold value, the mode is switched from the motor running mode to the hybrid running mode.

[0023] [Schematic Configuration of Fuel Supply System] Figure 2 is a schematic diagram of the fuel supply system A. The fuel supply system A includes an engine 10, a fuel tank 23, a main fuel pump 24a, a sub-fuel pump 24b, a low-pressure pipe 25, a low-pressure delivery pipe 26, a high-pressure delivery pipe 36, fuel pressure sensors 28 and 38, and a high-pressure fuel pump 40, etc.

[0024] Engine 10 is a spark-ignition type four-cylinder gasoline engine equipped with in-cylinder injection valves 37 that inject fuel into each cylinder and port injection valves 27 that inject fuel into each intake port. Engine 10 also includes a camshaft CPS that drives the intake valve or exhaust valve in conjunction with a crankshaft which is linked to a plurality of pistons.

[0025] The fuel tank 23 stores gasoline, which is the fuel. The main fuel pump 24a and the sub-fuel pump 24b are located inside the fuel tank 23. The main fuel pump 24a and the sub-fuel pump 24b are pumps with the same performance, such as head, but are not limited to these. The main fuel pump 24a pressurizes the fuel and discharges it to the low-pressure pipe 25 via the branch pipe 24ap. The sub-fuel pump 24b pressurizes the fuel and discharges it to the low-pressure pipe 25 via the branch pipe 24bp. The base ends of the branch pipes 24ap and 24bp are connected to the main fuel pump 24a and the sub-fuel pump 24b, respectively. The ends of the branch pipes 24ap and 24bp are connected to the low-pressure pipe 25. The branch pipes 24ap and 24bp are examples of the first and second branch pipes, respectively. The fuel discharged into the low-pressure pipe 25 is supplied to the port injection valve 27 via the low-pressure delivery pipe 26, and also to the high-pressure fuel pump 40 via the branch pipe 25a that branches off from the low-pressure pipe 25.

[0026] The high-pressure fuel pump 40 pressurizes the fuel supplied from the branch pipe 25a and discharges it into the high-pressure delivery pipe 36. The fuel pressurized by the high-pressure fuel pump 40 is supplied to the in-cylinder injection valve 37 via the high-pressure delivery pipe 36.

[0027] The fuel pressure sensors 28 and 38 detect the fuel pressure in the low-pressure delivery pipe 26 and the high-pressure delivery pipe 36, respectively. The ECU 100 acquires the detected values ​​from the fuel pressure sensors 28 and 38.

[0028] Furthermore, the ECU 100 changes the in-cylinder injection ratio, which is the ratio of the amount of fuel injected from the in-cylinder injection valve 37 to the total amount of fuel injected, according to the operating range of the engine 10. For example, when the engine 10 is operating in a low-load range, the in-cylinder injection ratio is 0%, in a high-load range it is 100%, and in a medium-load range it is set to an intermediate value.

[0029] The high-pressure fuel pump 40 is equipped with a cylinder 41, a plunger 42, a pressurizing chamber 43, an intake passage 45, a discharge passage 47, a relief passage 49, an intake valve 50, a discharge valve 60, and a relief valve 70. The plunger 42 is biased by a spring toward the cam CP, which rotates together with the cam shaft CPS, and reciprocates within the cylinder 41 as the cam CP rotates. The pressurizing chamber 43 is defined by the cylinder 41 and the plunger 42. The volume of the pressurizing chamber 43 decreases as the plunger 42 rises. The volume of the pressurizing chamber 43 increases as the plunger 42 descends.

[0030] The intake passage 45 connects the branch pipe 25a, which branches off from the low-pressure pipe 25, to the pressurizing chamber 43. The intake passage 45 is provided with a pulsation damper 44 to suppress fuel pressure pulsation. The relief passage 49 connects the pressurizing chamber 43 to the high-pressure delivery pipe 36. The discharge passage 47 connects the relief passage 49 on the pressurizing chamber 43 side of the discharge valve 60 to the relief passage 49 on the high-pressure delivery pipe 36 side of the discharge valve 60.

[0031] The intake valve 50 is located on the fuel inlet side of the pressurizing chamber 43 and switches the communication state between the intake passage 45 and the pressurizing chamber 43. The intake valve 50 has a valve body 51, a coil 55 that drives the valve body 51, and a spring 53 that always biases the valve body 51 in the open direction. When the coil 55 is energized, the valve body 51 blocks the intake passage 45 and the pressurizing chamber 43 against the biasing force of the spring 53. When the coil 55 is not energized, the valve body 51 is maintained in the open state by the biasing force of the spring 53. The discharge valve 60 is located on the discharge passage 47 and is a check valve that allows the flow of fuel from the pressurizing chamber 43 side to the high-pressure delivery pipe 36 side but restricts the flow in the reverse direction.

[0032] During the intake stroke of the high-pressure fuel pump 40, the intake valve 50 opens and the plunger 42 descends, filling the pressurizing chamber 43 from the branch pipe 25a through the intake passage 45. During the pressurizing stroke, the intake valve 50 closes and the volume of the pressurizing chamber 43 decreases as the plunger 42 rises, pressurizing the fuel in the pressurizing chamber 43. During the discharge stroke, the discharge valve 60 opens when the fuel pressure acting on the discharge valve 60 from the pressurizing chamber 43 side becomes greater due to the fuel pressure acting on the discharge valve 60 from the high-pressure delivery pipe 36 side and the biasing force of the discharge valve 60's spring. As a result, the pressurized fuel is supplied to the high-pressure delivery pipe 36.

[0033] The relief valve 70 is located on the relief passage 49 and allows fuel to flow from the high-pressure delivery pipe 36 to the pressurizing chamber 43, but restricts flow in the reverse direction. The relief valve 70 opens when the fuel pressure in the high-pressure delivery pipe 36 rises excessively, to the point where it could cause abnormalities in the high-pressure delivery pipe 36 or the in-cylinder injection valve 37.

[0034] The ECU 100 controls the system to a first drive state, where only the main fuel pump 24a is driven, if the requested output to the engine 10 is below a threshold. If the requested output to the engine 10 is greater than the threshold, the ECU 100 controls the system to a second drive state, where both the main fuel pump 24a and the sub-fuel pump 24b are driven. By driving both the two main fuel pumps 24a and the sub-fuel pump 24b, the amount of fuel supplied to the port injection valves 27 of the engine 10 can be ensured. In this way, the ECU 100 switches between the first drive state and the second drive state according to the requested output to the engine 10. Switching between the first drive state and the second drive state is an example of processing performed by the control unit.

[0035] [Sub-fuel pump malfunction diagnosis and control] Figure 3 is a flowchart illustrating the sub-fuel pump malfunction diagnosis control. The ECU 100 determines whether or not the vehicle is in hybrid driving mode (step S1). In other words, the ECU 100 determines whether or not the vehicle is running on engine 10. If the answer in step S1 is No, this control terminates. If the answer in step S1 is Yes, the ECU 100 determines whether or not the vehicle is in the first driving state where only the main fuel pump 24a is running and the sub-fuel pump 24b is stopped (step S2). If the answer in step S2 is No, this control terminates.

[0036] If the answer in step S2 is Yes, the ECU 100 determines whether the abnormality diagnosis conditions for the sub-fuel pump 24b have been met (step S3). The abnormality diagnosis conditions include (1) the fuel pressure supplied to the port injection valve 27 in the first drive state is above a predetermined value, (2) the vehicle speed is above a predetermined speed, and (3) the abnormality diagnosis of the sub-fuel pump 24b has not been performed during the current trip.

[0037] The fuel pressure in condition (1) is the fuel pressure obtained by the fuel pressure sensor 28. The predetermined value in condition (1) will be explained in detail later. The predetermined speed in condition (2) is set to the minimum vehicle speed at which the driver will not notice the operating noise caused by the forced operation of the sub-fuel pump 24b, which will be explained later, and will not cause the driver any discomfort. This is to prevent the driver from feeling uncomfortable due to the forced operation of the sub-fuel pump 24b, which will be explained later. Condition (3) is a condition to avoid the forced operation of the sub-fuel pump 24b, which will be explained later, being performed multiple times during one trip. This is because the forced operation of the sub-fuel pump 24b is an exceptional control, and if it is performed multiple times during one trip, it may cause discomfort to the driver, and the forced operation may also increase power consumption.

[0038] Furthermore, the abnormality diagnosis conditions may also include conditions such as the operating state of engine 10 not being transient and engine 10 having completed warm-up. If at least one of the abnormality diagnosis conditions is not met, the result is determined as No in step S3 and this control terminates.

[0039] If the answer in step S3 is Yes, the ECU 100 forces the sub-fuel pump 24b to operate (step S4). In this forced operation, the rotational speed of the sub-fuel pump 24b is controlled to a rotational speed at which fuel cannot be discharged from the sub-fuel pump 24b to the branch pipe 24bp if the fuel pressure supplied to the port injection valve 27 in the first operating state is greater than or equal to the predetermined value described above.

[0040] Figures 4A and 4B illustrate the differences in fuel discharge state depending on the rotational speed when the sub-fuel pump 24b is forcibly driven. In the first driving state, the fuel pressure supplied to the port injection valve 27 is controlled to a desired fuel pressure according to the operating state of the engine 10. For example, as shown in Figure 4A, when fuel is supplied to the port injection valve 27 from both the main fuel pump 24a and the sub-fuel pump 24b by forcibly driving the sub-fuel pump 24b, the fuel pressure supplied to the port injection valve 27 rises above the desired fuel pressure. As a result, the amount of fuel injected from the port injection valve 27 increases, which may affect the operating state of the engine 10 and cause discomfort to the driver.

[0041] In this embodiment, when the sub-fuel pump 24b is forcibly driven, the rotational speed is controlled to a speed at which fuel cannot be discharged from the sub-fuel pump 24b to the branch pipe 24bp. In other words, when the fuel pressure supplied to the port injection valve 27 in the first drive state is above a predetermined value, the rotational speed of the sub-fuel pump 24b during forced drive is controlled to a speed at which fuel cannot be discharged from the sub-fuel pump 24b. As a result, as shown in Figure 4B, the impeller of the sub-fuel pump 24b rotates, but it cannot overcome the fuel pressure received from the main fuel pump 24a, and therefore no fuel is discharged from the sub-fuel pump 24b to the branch pipe 24bp. Consequently, the sub-fuel pump 24b can be forcibly driven without increasing the fuel pressure supplied to the port injection valve 27.

[0042] Furthermore, the higher the fuel pressure supplied to the port injection valve 27 in the first drive state, the higher the maximum rotational speed at which fuel cannot be discharged from the sub-fuel pump 24b to the branch pipe 24bp during forced drive. Therefore, the predetermined value mentioned above and the rotational speed of the sub-fuel pump 24b during forced drive are determined based on experimental and simulation results to be the value at which fuel cannot be discharged from the sub-fuel pump 24b.

[0043] Next, the ECU 100 performs an abnormality diagnosis of the sub-fuel pump 24b based on the voltage and current values ​​applied to the sub-fuel pump 24b while the sub-fuel pump 24b is being forcibly driven (step S5). For example, if at least one of the voltage or current values ​​applied to the sub-fuel pump 24b is outside the normal range, the sub-fuel pump 24b is diagnosed as abnormal. If the sub-fuel pump 24b is diagnosed as abnormal, the ECU 100 may notify the system of the abnormality of the sub-fuel pump 24b by displaying this information on a display provided on the instrument panel of the hybrid vehicle 1, for example. Steps S4 and S5 are examples of processes performed by the diagnostic unit.

[0044] As described above, by forcibly driving the sub-fuel pump 24b in the first drive state at a rotational speed at which fuel cannot be discharged from the sub-fuel pump 24b to the branch pipe 24bp, the frequency of abnormality diagnosis of the sub-fuel pump 24b is ensured without causing discomfort to the driver. Furthermore, by limiting the rotational speed during forced driving of the sub-fuel pump 24b,

[0045] In the above embodiment, a hybrid vehicle 1 was used as an example, but the invention is not limited to this, and an engine-powered vehicle equipped with an engine as a driving power source may also be used.

[0046] Although embodiments of the present invention have been described in detail above, the present invention is not limited to these specific embodiments, and various modifications and changes are possible within the scope of the gist of the present invention as described in the claims. [Explanation of symbols]

[0047] 1. Hybrid vehicle 10 Engines 24a Main fuel pump 24b Sub-fuel pump 24ap branch pipe (1st branch pipe) 24bp branch pipe (second branch pipe) 27-port injection valve 37 In-cylinder injection valve 40 High-pressure fuel pump 100 ECUs (Control Units, Control Units, Diagnostic Units)

Claims

1. An engine having port injection valves, A main fuel pump and a sub-fuel pump are located inside the fuel tank, First and second branch pipes through which fuel pressurized by the main fuel pump and sub-fuel pump, respectively, is discharged. A low-pressure pipe that communicates with the first and second branch pipes and supplies fuel to the port injection valve, The system includes a control device for controlling the main fuel pump and the sub-fuel pump, The control device is A control unit that switches between a first drive state in which the main fuel pump is driven and the sub-fuel pump is stopped, or a second drive state in which both the main fuel pump and the sub-fuel pump are driven, depending on the magnitude of the engine's required output, The system includes a diagnostic unit that, when abnormality diagnosis conditions are met, including the fuel pressure supplied to the port injection valve in the first driving state being greater than or equal to a predetermined value, forcibly drives the sub-fuel pump and performs an abnormality diagnosis of the sub-fuel pump, The diagnostic unit controls the rotational speed of the sub-fuel pump in a forced drive state to a rotational speed at which fuel cannot be discharged from the sub-fuel pump to the second branch pipe when the fuel pressure supplied to the port injection valve in the first drive state is equal to or greater than the predetermined value, in a vehicle.

2. The vehicle according to claim 1, wherein the abnormality diagnosis condition includes the vehicle speed being equal to or greater than a predetermined speed.

3. The vehicle according to claim 2, wherein the abnormality diagnosis condition includes the fact that the abnormality diagnosis has not been performed during the current trip.

4. The engine has an in-cylinder injection valve, A vehicle according to any one of claims 1 to 3, further comprising a high-pressure fuel pump that pressurizes the fuel pressurized by the main fuel pump and sub-fuel pump and supplies it to the in-cylinder injection valve.

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