Vehicle control device

Abstract

To secure an opportunity of air purge for sufficiently venting air.SOLUTION: A vehicle control device (100) for executing air purge for discharging air in fuel piping (25) connected to a fuel injection valve (24) of an internal combustion engine (3) includes control means (101-103) for executing the air purge by cranking the internal combustion engine (3) by using an electric motor (1) with variable output and performing fuel injection for the air purge by using the fuel injection valve (24). In the cranking by using the electric motor (1) during execution of the air purge, the control means (101-103) lowers a degree of increase of speed of the internal combustion engine (3) compared to cranking when the air purge has been completed.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a vehicle control device for performing an air purge to discharge air from a fuel pipe connected to a fuel injection valve of an internal combustion engine. [Background technology]

[0002] An internal combustion engine mounted on a vehicle is equipped with a fuel supply system that includes fuel injection valves and fuel piping (delivery pipes). After the fuel supply system is installed in the vehicle at the factory or after the fuel supply system components are rearranged, air may remain in the fuel piping. Therefore, when starting the engine for the first time after the fuel supply system is installed or after the fuel supply system components are rearranged, the engine is cranked, fuel is injected by the fuel injection valve, and an air purge is performed to expel air from the fuel piping. At this time, insufficient fuel pressure can easily cause a start delay compared to a normal start, and an improvement is desired. Patent Document 1 discloses a method for bleeding air from a fuel supply system, in which the fuel injection valve is held fully open during cranking to discharge air from the delivery pipe through the fuel injection valve, and when initial exposure is detected, normal fuel injection valve control is performed. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 8-326583 Summary of the Invention [Problem to be solved by the invention]

[0004] When fuel injection for air purging is performed, a mechanism may be used in which the fuel injection for air purging is stopped when the engine speed reaches a threshold value, as in Patent Document 1. Patent Document 1 discloses that if an increase in engine speed is detected and an initial explosion is detected, the control is switched to normal fuel injection valve control. However, when the cranking speed is high, the engine speed increases to a high degree, which may result in the engine speed quickly reaching the threshold and the air purge fuel injection ending before the air has been sufficiently purged, thereby limiting the opportunity for air purging.

[0005] The present invention has been made in view of the above circumstances, and has as its object to ensure an opportunity for air purging to sufficiently remove air. [Means for solving the problem]

[0006] The vehicle control device of the present invention is a vehicle control device for performing an air purge to discharge air from a fuel pipe connected to a fuel injection valve of an internal combustion engine, and is equipped with a control means for cranking the internal combustion engine using an electric motor with variable output, injecting fuel for air purge using the fuel injection valve, and performing air purge, and is characterized in that the control means reduces the degree of increase in the rotation speed of the internal combustion engine when cranking by the electric motor to perform air purge compared to cranking when air purge is completed. [Effects of the Invention]

[0007] According to the present invention, it is possible to ensure an opportunity for air purging to sufficiently remove air. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a diagram showing a schematic configuration of a vehicle according to an embodiment; [Figure 2] FIG. 2 is a diagram illustrating an example of the configuration of an engine. [Figure 3] 4 is a time chart showing a flow at the time of initial startup in the embodiment. [Figure 4] 4 is a time chart showing a flow at the time of initial startup in the embodiment. [Figure 5] 10 is a flowchart illustrating an example of an air purge process executed by the ECU. [Figure 6]6 is a time chart showing a flow at the time of initial startup in a comparative example. [Figure 7] 6 is a time chart showing a flow at the time of initial startup in a comparative example. DETAILED DESCRIPTION OF THE INVENTION

[0009] A vehicle control device according to one embodiment of the present invention is a vehicle control device (100) for performing air purging to discharge air from a fuel pipe (25) connected to a fuel injection valve (24) of an internal combustion engine (3), and includes control means (101-103) for cranking the internal combustion engine (3) using an electric motor (1) with a variable output, injecting fuel for air purging by the fuel injection valve (24), and performing air purging, and the control means (101-103) reduces the degree of increase in the rotation speed of the internal combustion engine (3) during cranking by the electric motor (1) when performing air purging compared to cranking when air purging is completed. This ensures that there is sufficient opportunity for air purging to remove the air. [Example]

[0010] Preferred embodiments of the present invention will now be described with reference to the accompanying drawings. FIG. 1 is a diagram showing a schematic configuration of a vehicle according to an embodiment. The vehicle of this embodiment is a series-type hybrid vehicle that uses the engine as a generator and the motor as a power source, and is equipped with a power generation motor generator 1 (hereinafter referred to as power generation MG), a drive motor generator 2 (hereinafter referred to as drive MG), and an internal combustion engine 3.

[0011] The vehicle is equipped with a transaxle 4 equipped with a generator MG1 and a drive MG2. An engine 3 is connected to the generator MG1. The engine 3 is used as a generator and is not mechanically connected to the drive wheels 5. When starting the engine 3, cranking is performed by the generator MG1. The drive MG2 is mechanically connected to the drive wheels 5 via a transmission or the like. The drive MG2 is a power source that generates power for running the vehicle via a reduction gear.

[0012] The vehicle is also equipped with a high-voltage battery 6. The power generation MG 1 is connected to the high-voltage battery 6 via a high-voltage line 7, an inverter 8a, and a boost converter 9. The drive MG 2 is also connected to the high-voltage battery 6 via a high-voltage line 7, an inverter 8b, and a boost converter 9. The power generation MG 1 and the drive MG 2 function as electric motors that use the high-voltage battery 6 as a power source and vary their output through inverter control. In this way, the high-voltage battery 6 is used to drive the vehicle.

[0013] The vehicle also includes an auxiliary device 10 and a low-voltage battery 11 that serves as a power source for the auxiliary device 10. In this manner, the low-voltage battery 11 is used to supply power to the auxiliary device system.

[0014] The vehicle is also equipped with an ECU (Electronic Control Unit) 100. Power is supplied to the ECU 100 from a high-voltage battery 6 via a DC-DC converter 12. The ECU 100 functions as an HCU (Hybrid Vehicle Control Unit) that manages driving force. The ECU 100 also functions as an ECM (Engine Control Module) that controls the engine 3 based on requests from the HCU, and as a BMS (Battery Management System) that monitors the state of the high-voltage battery 6. The functional configuration of the ECU 100 and the processing executed by the ECU 100 will be described in detail later, but in this embodiment, the ECU 100 functions as a control device for a vehicle to which the present invention is applied.

[0015] Next, an example of the configuration of the engine 3 will be described with reference to Fig. 2. Fig. 2 is a diagram showing an example of the configuration of the engine 3. The engine 3 is provided with a crankshaft 13 rotatably supported therein and a piston 15 that reciprocates in a cylinder 14 as the crankshaft 13 rotates. The engine 3 is also formed with a combustion chamber 16, an intake port 17 that communicates with the combustion chamber 16, and an exhaust port 18. A spark plug 19 is provided facing the combustion chamber 16. An intake passage 20 is connected to the intake port 17, and an intake valve 21 is provided to open and close the intake port 17. An exhaust passage 22 is connected to the exhaust port 18, and an exhaust valve 23 is provided to open and close the exhaust port 18. A throttle valve 26 and an injector 24 located downstream of the throttle valve 26 are provided in the intake passage 20. The injector 24 is a fuel injection valve that injects fuel supplied via a fuel piping (delivery pipe) 25.

[0016] Furthermore, although not shown, the engine 3 is equipped with various sensors, such as a rotation speed sensor that measures the engine rotation speed, an opening sensor that measures the opening of the throttle valve 26, and an air flow sensor that measures the amount of air in the intake passage 20. The ECU 100 controls the engine, such as the opening and closing operation of the throttle valve 26, fuel injection by the injector 24, the opening and closing timing of the intake valve 21 and the exhaust valve 23, and the ignition timing by the spark plug 19, in accordance with the detection results of the various sensors. Note that, for engine control during normal operation, known techniques may be applied, and detailed description thereof will be omitted here.

[0017] The following is a detailed description of the air purge that discharges air from the fuel pipe 25. The air purge is performed at the first start after the fuel supply system is assembled or after the components of the fuel supply system are rearranged. 1 shows the functional configuration of an ECU 100 for executing air purging. The ECU 100 includes a determination unit 101, a cranking control unit 102, and a fuel injection control unit 103. The determination unit 101 determines whether the engine speed has reached a threshold value. The threshold value includes an air purge fuel injection speed, a normal fuel injection speed, and an air purge complete combustion determination speed, as will be described later. The cranking control unit 102 controls the power generation MG1 to crank the engine 3. The cranking control unit 102 performs inverter control, and when cranking by the power generation MG1 to perform air purging, the degree of increase in engine speed is reduced compared to normal cranking (cranking when air purging is completed). The fuel injection control unit 103 controls the injector 24. The fuel injection control unit 103 sets the fuel injection amount for the air purge fuel injection (air purge fuel injection amount) to be greater than the fuel injection amount for the fuel injection during normal cranking (normal fuel injection amount) (normal fuel injection amount). In this embodiment, the determining unit 101, cranking control unit 102, and fuel injection control unit 103 function together as the control means of the present invention.

[0018] First, the flow of air purging in a comparative example will be described with reference to Figures 6 and 7. Air purging is performed at the first start after the fuel supply system is assembled or after the fuel supply system components are rearranged. Note that in the comparative example, the same components as in this embodiment will be described with the same reference numerals. In the comparative example, cranking is performed by a starter motor when starting the engine 3. The starting torque of the starter motor is designed to be sufficient to start the engine by cranking. Although the term "starter motor" is used, a configuration in which cranking is performed by the generator MG1 as in the example of FIG. 1, and the starting torque is always constant (torque equivalent to the starting torque of the starter motor), also falls under the comparative example.

[0019] Figure 6 is a time chart showing the flow at initial startup in a comparative example. Figure 6(a) shows the time series change in engine speed, (b) shows the time series change in on / off of the starter motor, (c) shows the time series change in on / off of fuel injection for air purge, (d) shows the time series change in on / off of normal fuel injection, and (e) shows the time series change in on / off of air purge completion determination. As shown in FIG. 6, cranking is started by the starter motor (timing t0). When the engine speed increases due to cranking and reaches the air purge fuel injection speed (timing t1), fuel injection for air purge is performed by the injector 24. The fuel injection amount for air purge fuel injection (air purge fuel injection amount) is set to be larger than the fuel injection amount for normal fuel injection (normal fuel injection amount), and the air is pushed out and discharged from the fuel pipe 25.

[0020] While the air purge fuel injection is being performed, cranking by the starter motor is stopped (timing t2), and when the engine speed reaches the normal fuel injection speed (timing t3), the amount of fuel injection for air purge is switched from the amount of fuel injection for air purge to the amount of normal fuel injection (amount of fuel injection for air purge > amount of normal fuel injection) in order to prevent excess fuel consumption and smoldering of the spark plug 19. If sufficient air has been removed, fuel is injected appropriately from the injector 24, the engine speed increases, and complete combustion occurs (timing t4). When the engine speed further increases and reaches an engine speed at which it can be determined that air purging has been performed appropriately (air purge complete combustion determination speed) (timing t5), it is determined that air purging has been completed (air purge completion determination ON). When the air purge completion determination is ON, normal fuel injection will occur from the next start.

[0021] Figure 7 is a time chart showing the flow of the initial start-up in a comparative example, showing a case where a poor start occurs. Figure 7(a) shows the time series change in engine speed, (b) shows the time series change in the on / off of the starter motor, (c) shows the time series change in the on / off of the fuel injection for air purge, (d) shows the time series change in the on / off of the normal fuel injection, and (e) shows the time series change in the on / off of the air purge completion determination. The ease of bleeding air from the fuel pipe 25 depends on the amount of air in the fuel pipe 25 and the location of the remaining air in the fuel pipe 25 (whether it is in a location where the air can easily flow). As shown in Figure 7, if the air is not sufficiently bled, when the fuel injection amount for air purge is switched to the normal fuel injection amount (timing t3), the fuel will not be injected properly from the injector 24, the engine speed will not increase steadily, and there will be a delay before the air purge complete combustion determination speed is reached (timing t5'). Alternatively, the engine 3 may stop, requiring re-cranking.

[0022] Next, the flow of air purging in the embodiment will be described with reference to Figures 3 and 4. Air purging is performed at the first start after the fuel supply system is assembled or after the parts of the fuel supply system are rearranged. Figure 3 is a time chart showing the flow at initial startup in this embodiment. Figure 3(a) shows the time series change in engine speed, (b) shows the time series change in the on / off state of the generator MG1 and the magnitude of the starting torque, (c) shows the time series change in the on / off state of the air purge fuel injection, and (d) shows the time series change in the on / off state of the normal fuel injection. In Figures 3(a) to 3(d), the comparative examples described in Figures 6 and 7 are indicated by dotted lines. As shown in FIG. 3, cranking is started with the generator MG1 (timing T0). The output of the generator MG1 is variable under inverter control. When cranking is performed with the generator MG1, the starting torque is normally about the same as that of the starter motor described in FIG. 6, for example. However, as shown in FIG. 3(a), at the initial start, the starting torque of the generator MG1 is made smaller than that of the starter motor. In this way, when cranking with the generator MG1 to perform air purging, the degree of increase in engine speed is made lower than when cranking after air purging is completed.

[0023] When the engine speed increases due to cranking and reaches the air purge fuel injection speed (timing T1), fuel injection for air purge is performed by the injector 24. The fuel injection amount for air purge fuel injection (air purge fuel injection amount) is set to be larger than the fuel injection amount for normal fuel injection (normal fuel injection amount), and air is pushed out and discharged from the fuel pipe 25. Although the fuel injection amount for air purge is set to be larger than the normal fuel injection amount, it is preferable to set the fuel injection amount to the minimum amount necessary to perform air purge depending on the degree of increase in engine speed, so as to prevent smoldering of the spark plug 19 due to adhesion of fuel droplets, etc.

[0024] While fuel injection for air purge is being performed, cranking by the generator MG1 is stopped (timing T2), and when the engine speed reaches the normal fuel injection speed (timing T3), the fuel injection amount for air purge is switched to the normal fuel injection amount (air purge fuel injection amount > normal fuel injection amount) to prevent excess fuel consumption and smoldering of the spark plug 19. After that, although not shown, as in the comparative example of Figure 6, when the engine speed reaches the air purge complete combustion judgment speed, the air purge completion judgment is turned on. When the air purge completion judgment is turned on, normal fuel injection is performed from the next start.

[0025] 4 is a time chart showing the flow at the time of initial start-up in this embodiment, and shows a case where starting failure occurs due to, for example, smoldering of the spark plug 19. Fig. 4(a) shows the time series change in engine speed, (b) shows the time series change in the on / off of the generator MG1 and the magnitude of the starting torque, (c) shows the time series change in the on / off of the air purge fuel injection, (d) shows the time series change in the on / off of the normal fuel injection, (e) shows the time series change in the on / off of the long crank determination, and (f) shows the time series change in the on / off of the air purge completion determination. As shown in FIG. 4, cranking is initiated by the generator MG 1 (timing T0). When the air purge fuel injection speed is reached (timing T1), air purge fuel injection is initiated by the injector 24. If the engine speed does not stabilize and does not reach the normal fuel injection speed within the long crank determination time from timing T1 (timing T6), a long crank is determined (long crank determination), and the air purge fuel injection is stopped. The output of the generator MG 1 is increased to forcibly increase the engine speed (forced cranking). When the engine speed reaches the air purge complete combustion determination speed (timing T5), forced cranking by the generator MG 1 is stopped, and normal fuel injection is initiated by the injector 24. In this case, the ignition period of the spark plug 19 may be shortened to increase the temperature and eliminate smoldering. When forced cranking is initiated, the air purge completion determination is turned on when the completion determination time has elapsed since the engine speed reached the air purge complete combustion determination speed. The reason for waiting for the completion determination time to elapse is to maintain a constant engine speed (for example, idling) with normal fuel injection. Once the air purge completion determination is turned on, normal fuel injection will be performed from the next start.

[0026] FIG. 5 is a flowchart showing an example of the air purge process executed by the ECU 100. In step S1, when the ECU 100 receives a test signal indicating that the engine is being started for the first time after the fuel supply system has been assembled or after the components of the fuel supply system have been rearranged, the process proceeds to step S2. In step S2, the cranking control unit 102 controls the generator MG 1 to perform cranking for air purging. Specifically, as described in Fig. 3, cranking is started by the generator MG 1 (timing T0). The starting torque of the generator MG 1 at this time is set to be smaller than the starting torque during normal operation. In step S3, the fuel injection control unit 103 controls the injector 24 to perform fuel injection for air purge. Specifically, as described in Fig. 3, when the determination unit 101 determines that the engine speed has reached the air purge fuel injection speed (timing T1), the injector 24 performs fuel injection for air purge (air purge fuel injection amount>normal fuel injection amount).

[0027] In step S4, the determination unit 101 determines whether the engine speed has reached the normal fuel injection speed. If the engine speed has reached the normal fuel injection speed, the process proceeds to step S5. If the engine speed has not reached the normal fuel injection speed, the process proceeds to step S6. In step S6, the determination unit 101 determines whether or not the long crank determination time has elapsed since the timing T1 of the air purge fuel injection, as described in Fig. 4. If the long crank determination time has elapsed, the process proceeds to step S7. If the long crank determination time has not elapsed, the process returns to step S2, and the air purge cranking and air purge fuel injection are continued. In step S7, the cranking control unit 102 controls the generator MG1 to perform forced cranking. Specifically, as described in Fig. 4, the fuel injection for air purge is stopped and the output of the generator MG1 is increased to forcibly increase the engine speed (timing T6). Then, when the determination unit 101 determines that the engine speed has reached the air purge complete combustion determination speed (timing T5), the forced cranking is stopped and the process proceeds to step S5.

[0028] In step S5, the fuel injection control unit 103 controls the injector 24 to perform normal fuel injection. In step S8, the determination unit 101 determines whether or not air purge has been completed based on the relationship between the engine speed and the air purge complete combustion determination speed, and if the air purge completion determination is ON, the process ends.

[0029] As described above, when cranking with the generator MG1 to perform air purging, the increase in engine speed is made lower than when cranking after air purging is complete. This allows the air purging time to be extended, as shown in Figure 3, ensuring an opportunity for air purging to sufficiently remove air. Therefore, it is possible to prevent insufficient fuel pumping at the initial start and to prevent start-up delays from occurring more easily than during normal start-up.

[0030] Furthermore, when the engine speed reaches a predetermined speed (normal fuel injection speed), the amount of fuel injected by the injector 24 is changed to a normal fuel injection amount that is less than the air purge fuel injection amount, thereby making it possible to suppress excess fuel consumption and smoldering of the spark plug 19.

[0031] Furthermore, if the engine speed does not reach a predetermined speed (normal fuel injection speed) within a predetermined time (long crank determination time) after the start of air purge fuel injection, the output of the generator MG1 is increased, which forcibly increases the engine speed, suppresses smoldering of the spark plug 19, and prevents start-up delays.

[0032] Although the embodiments of the present invention have been described in detail above with reference to the drawings, each embodiment merely shows a specific example of how the present invention can be implemented. The technical scope of the present invention is not limited to each embodiment. Various modifications of the present invention are possible within the scope of the gist of the present invention, and these modifications are also included within the technical scope of the present invention. Although the present embodiment has been described with reference to a series hybrid vehicle, the present invention is not limited to this and can be widely applied to vehicles capable of cranking an internal combustion engine using a variable output electric motor. A vehicle control device to which the present invention is applied is configured by a computer device equipped with, for example, a CPU, ROM, RAM, etc., and the functions of each means are realized by the CPU executing a predetermined program stored, for example, in the ROM. [Explanation of symbols]

[0033] 1: power generating motor generator, 3: engine, 6: high voltage battery, 8a: inverter, 24: injector, 25: fuel pipe, 100: ECU, 101: determination unit, 102: cranking control unit, 103: fuel injection control unit

Claims

1. A vehicle control device for performing an air purge to discharge air from a fuel pipe connected to a fuel injection valve of an internal combustion engine, a control means for cranking the internal combustion engine using an electric motor with a variable output, and for injecting fuel for air purging by the fuel injection valve to perform air purging; The control device for a vehicle is characterized in that, when cranking by the electric motor when performing an air purge, the control means reduces the degree of increase in the rotation speed of the internal combustion engine compared to cranking when the air purge is completed.

2. 2. The vehicle control device according to claim 1, wherein the control means changes the fuel injection amount by the fuel injection valve to a fuel injection amount that is less than the fuel injection amount for the air purge when the rotation speed of the internal combustion engine reaches a predetermined rotation speed.

3. 3. The vehicle control device according to claim 1, wherein the control means increases the output of the electric motor when the rotation speed of the internal combustion engine does not reach a predetermined rotation speed until a predetermined time has elapsed after the start of the air purge fuel injection by the fuel injection valve.

4. The vehicle includes a high-voltage battery used for driving the vehicle and a low-voltage battery used for supplying power to auxiliary equipment.

3. The vehicle control device according to claim 1, wherein the electric motor is connected to the high-voltage battery via an inverter.

Images