Control device for hybrid vehicle

Abstract

To suppress generation of vapor in a low-pressure delivery pipe, a low-pressure pipe, a high-pressure delivery pipe, a high-pressure pipe, and a high-pressure pump.SOLUTION: Provided is a control device for a hybrid vehicle. The hybrid vehicle comprises: an engine that is a traveling power source having a low-pressure delivery pipe and a high-pressure delivery pipe; and a motor that is a traveling power source capable of generating power based on power of the engine. The control device for a hybrid vehicle comprises an injection rate controlling unit for controlling a port injection rate that is a ratio of a fuel injection amount from a port injection valve relative to a total of a fuel injection amount from the port injection valve and that of an in-cylinder injection valve. In the case that external power supply is carried out by causing the motor to generate power using power of the engine when the vehicle is stopped, the control device of the hybrid vehicle determines whether or not a temperature of the high-pressure fuel is higher than a temperature of the low-pressure fuel. Then: in the case of affirmative determination, the control device decreases the port injection rate and increases the in-cylinder injection rate relative to the rates in the case of negative determination; and in the case of negative determination, the control device increases the port injection rate and decreases the in-cylinder injection rate.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a control device for a hybrid vehicle. [Background technology]

[0002] There is a hybrid vehicle equipped with an engine and a motor as a driving power source. The motor can generate electricity using the power of the engine. The engine has a port injection valve, an in-cylinder injection valve, a low-pressure delivery pipe, a low-pressure pipe, a high-pressure delivery pipe, a high-pressure pipe, and a high-pressure pump (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-156355 Summary of the Invention [Problem to be solved by the invention]

[0004] While the vehicle is stopped, it is possible to generate electricity from the engine to power the motor and supply it to an external power source. In this case, the engine cannot be cooled by the wind while the vehicle is stopped, and there is a risk that the engine will become too hot. As a result, the fuel may become overheated in any of the low-pressure delivery pipe, low-pressure pipe, high-pressure delivery pipe, high-pressure pipe, or high-pressure pump, generating vapor and reducing the accuracy of air-fuel ratio control.

[0005] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide a control device for a hybrid vehicle that suppresses the generation of vapor in the low-pressure delivery pipe, low-pressure pipe, high-pressure delivery pipe, high-pressure pipe, and high-pressure pump. [Means for solving the problem]

[0006] The object is to provide a control device for a hybrid vehicle including an engine as a power source for running, the engine having a port injection valve, an in-cylinder injection valve, a low-pressure delivery pipe for supplying low-pressure fuel to the port injection valve, and a high-pressure delivery pipe for supplying high-pressure fuel having a higher pressure than the low-pressure fuel to the in-cylinder injection valve, and a motor as a power source for running, capable of generating electricity based on the power of the engine, the control device including an injection rate control unit that controls a port injection rate, which is the ratio of fuel injection from the port injection valve to a total fuel injection amount from the port injection valve and the in-cylinder injection valve, and an in-cylinder injection rate, which is the ratio of the fuel injection amount from the in-cylinder injection valve to the total fuel injection amount, and a control unit that controls the motor to generate electricity using the power of the engine while the vehicle is stopped. This can be achieved by a control device for a hybrid vehicle, which includes an external power supply determination unit that determines whether or not a vehicle-stopped external power supply process that supplies external power is being executed, and a fuel temperature determination unit that, if a positive determination is made by the external power supply determination unit, performs a temperature determination to determine whether or not the high-pressure fuel is hotter than the low-pressure fuel, wherein, if a positive determination is made by the external power supply determination unit and the fuel temperature determination unit, the injection rate control unit decreases the port injection rate and increases the in-cylinder injection rate more than when a negative determination is made by the external power supply determination unit, and if a positive determination is made by the external power supply determination unit and a negative determination is made by the fuel temperature determination unit, the injection rate control unit increases the port injection rate and decreases the in-cylinder injection rate more than when a negative determination is made by the external power supply determination unit.

[0007] The engine temperature determination unit may determine whether the temperature of the engine is higher than a first threshold value, and an ambient temperature determination unit may determine whether the ambient temperature around the engine is higher than a second threshold value, and when the external power supply determination unit, the engine temperature determination unit, and the ambient temperature determination unit make positive determinations, the fuel temperature determination unit may execute the temperature determination. [Effects of the Invention]

[0008] A control device for a hybrid vehicle can be provided that suppresses the generation of vapor in the low-pressure delivery pipe, low-pressure pipe, high-pressure delivery pipe, high-pressure pipe, and high-pressure pump. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a schematic diagram of a hybrid vehicle. [Figure 2] FIG. 1 is a schematic diagram of an engine. [Figure 3] 4 is a flowchart illustrating vapor generation suppression control. DETAILED DESCRIPTION OF THE INVENTION

[0010] [Hybrid vehicle configuration] 1 is a schematic diagram of a hybrid vehicle 1. The hybrid vehicle 1 includes an engine 10, a first motor 61, a second motor 62, a power split mechanism 63, a transmission mechanism 64, drive wheels 70, a PCU 80, a battery 90, a voltage converter 92, an external power feed port 94, and an ECU (Electronic Control Unit) 100. The engine 10, the first motor 61, and the second motor 62 are mounted as drive sources for driving the hybrid vehicle 1.

[0011] The first motor 61 and the second motor 62 are connected to the battery 90 via the PCU 80. The first motor 61 and the second motor 62 function as motors that generate driving force for the vehicle in response to power supplied from the battery 90. Furthermore, the first motor 61 and the second motor 62 also function as generators that generate regenerative power to charge the battery 90 in response to power transmission from the engine 10 and the drive wheels 70. The power exchanged between the first motor 61 and the second motor 62 and the battery 90 is adjusted by the PCU 80. The PCU 80 is controlled by the ECU 100. The PCU 80 converts a DC voltage from the battery 90 into an AC voltage, or converts an AC voltage from the first motor 61 or the second motor 62 into a DC voltage.

[0012] The power split mechanism 63 mechanically couples the crankshaft of the engine 10, the rotating shaft of the first motor 61, and the output shaft of the power split mechanism 63. The power split mechanism 63 is, for example, a planetary gear mechanism including a sun gear, a planetary carrier, a pinion gear, and a ring gear. The output shaft of the power split mechanism 63 is coupled to a transmission mechanism 64. The rotating shaft of the second motor 62 is also coupled to the transmission mechanism 64. The driving forces of the engine 10, the first motor 61, and the second motor 62 are transmitted to the drive wheels 70 via the transmission mechanism 64.

[0013] The voltage converter 92 is driven by the ECU 100 during external power feeding. The voltage converter 92 converts DC power fed from the battery 90 into AC power and outputs it to an external power feed port 94. By connecting a connector (not shown) from the outside to the external power feed port 94, the power stored in the battery 90 can be supplied to, for example, a home power system. Furthermore, the ECU 100 can execute a vehicle-stop external power feeding process in which, while the vehicle is stopped, the engine 10 is driven to cause the first motor 61 to generate power, and the power is used to feed external power. Since external power can be fed while the first motor 61 is generating power, it is possible to feed power to, for example, an external device that requires a large amount of power.

[0014] The ECU 100 is an electronic control unit that includes a processing circuit that performs various types of calculations related to vehicle driving control and a memory that stores control programs and data. The ECU 100 is an example of a control device for the hybrid vehicle 1, and functionally realizes an external power supply determination unit, a fuel temperature determination unit, an injection rate control unit, an engine temperature determination unit, and an ambient temperature determination unit, which will be described in detail later.

[0015] The ECU 100 is electrically connected to a vehicle speed sensor 101, a crank angle sensor 102, a water temperature sensor 103, and an engine ambient temperature sensor 104. The vehicle speed sensor 101 detects the traveling speed of the hybrid vehicle 1. The crank angle sensor 102 detects the rotation speed of the engine 10. The water temperature sensor 103 detects the temperature of the cooling water that cools the engine 10. The engine ambient temperature sensor 104 is disposed in the engine compartment and detects the ambient temperature around the engine 10.

[0016] [Engine outline] 2 is a schematic diagram of the engine 10. The engine 10 includes a fuel tank 21, a low-pressure pump 22, a low-pressure pipe 25, a low-pressure delivery pipe 26, a high-pressure delivery pipe 36, fuel pressure sensors 28 and 38, fuel temperature sensors 29 and 39, and a high-pressure pump 40.

[0017] Engine 10 is a spark-ignition four-cylinder gasoline engine equipped with port injection valves 27 that inject fuel into each intake port and direct injection valves 37 that inject fuel into each cylinder. Engine 10 also includes a camshaft 15 that drives the intake valves or exhaust valves in conjunction with the crankshaft.

[0018] The fuel tank 21 stores fuel. The low-pressure pump 22 pressurizes the fuel in the fuel tank 21 and discharges it into a low-pressure pipe 25. The fuel discharged into the low-pressure pipe 25 is supplied to a port injection valve 27 via a low-pressure delivery pipe 26, and is also supplied to a high-pressure pump 40 via a high-pressure pipe 25a branching off from the low-pressure pipe 25. The high-pressure pump 40 pressurizes the fuel supplied from the high-pressure pipe 25a and discharges it into a high-pressure delivery pipe 36. The fuel pressurized by the high-pressure pump 40 is supplied to an in-cylinder injection valve 37 via the high-pressure delivery pipe 36.

[0019] 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 fuel temperature sensors 29 and 39 detect the fuel temperature in the low-pressure delivery pipe 26 and the high-pressure delivery pipe 36, respectively. The ECU 100 acquires the detection values of the fuel pressure sensors 28 and 38 and the fuel temperature sensors 29 and 39.

[0020] The ECU 100 changes the port injection rate and the in-cylinder injection rate according to the operating range of the engine 10. The port injection rate is the proportion of fuel injected from the port injection valve 27 to the total fuel injection rate from the port injection valve 27 and the in-cylinder injection valve 37. The in-cylinder injection rate is the proportion of fuel injected from the in-cylinder injection valve 37 to the total fuel injection rate. For example, when the operating range of the engine 10 is in the low load range, the port injection rate is 100% and the in-cylinder injection rate is 0%. When the operating range of the engine 10 is in the high load range, the port injection rate is 0% and the in-cylinder injection rate is 100%. When the operating range of the engine 10 is in the medium load range, the port injection rate and the in-cylinder injection rate are, for example, 50% each. The port injection rate and the in-cylinder injection rate are controlled so that the sum of the port injection rate and the in-cylinder injection rate is always 100%.

[0021] The high-pressure pump 40 includes a cylinder 41, a plunger 42, a pressurizing chamber 43, a suction passage 45, a discharge passage 47, a relief passage 49, a suction valve 50, a discharge valve 47a, and a relief valve 49a. The plunger 42 moves up and down within the cylinder 41 as a result of rotation of a cam CP that rotates together with the camshaft 15. The volume of the pressurizing chamber 43 increases and decreases as the plunger 42 moves up and down. The pressurizing chamber 43 is defined by the cylinder 41 and the plunger 42.

[0022] The suction passage 45 communicates the pressurization chamber 43 with the high-pressure pipe 25a branching off from the low-pressure pipe 25. A pulsation damper 44 that suppresses fuel pressure pulsation is provided in the suction passage 45. A relief passage 49 communicates the pressurization chamber 43 with the high-pressure delivery pipe 36. The discharge passage 47 bypasses the relief valve 49a and communicates with the relief passage 49. The discharge valve 47a allows fuel to flow from the pressurization chamber 43 side to the high-pressure delivery pipe 36 side in the discharge passage 47, but prevents fuel from flowing in the reverse direction. The relief valve 49a allows fuel to flow from the high-pressure delivery pipe 36 side to the pressurization chamber 43 side in the relief passage 49, but prevents fuel from flowing in the reverse direction.

[0023] The intake valve 50 is a solenoid valve controlled by the ECU 100. When the intake valve 50 opens, the plunger 42 descends, and fuel is supplied from the high-pressure pipe 25a through the intake passage 45 into the pressurization chamber 43. Next, the intake valve 50 closes, the plunger 42 ascends, and the fuel in the pressurization chamber 43 is pressurized. Next, when the force of the fuel pressure acting on the discharge valve 47a from the pressurization chamber 43 side reaches or exceeds a predetermined pressure, the discharge valve 47a opens, and the pressurized fuel is supplied to the high-pressure delivery pipe 36. The relief valve 49a opens when the fuel pressure in the high-pressure delivery pipe 36 rises excessively.

[0024] [Vapor generation suppression control] 3 is a flowchart illustrating the vapor generation suppression control. The ECU 100 determines whether the above-described vehicle-stop external power feeding process is being executed (step S1). If the result in step S1 is No, this control ends. Step S1 is an example of a process executed by the external power feeding determination unit.

[0025] If the answer is Yes in step S1, the ECU 100 determines whether the coolant temperature is higher than a first threshold value T1 based on the water temperature sensor 103 (step S2). The first threshold value T1 is set to an upper limit value of the coolant temperature at which vapor is unlikely to be generated in any of the low-pressure delivery pipe 26, the low-pressure pipe 25, the high-pressure delivery pipe 36, the high-pressure pipe 25a, and the high-pressure pump 40. Here, the coolant temperature is an example of the temperature of the engine 10. Therefore, for example, the temperature of the engine oil that lubricates the engine 10 may be used as the temperature of the engine 10. If the answer is No in step S2, it is determined that vapor is unlikely to be generated in the low-pressure delivery pipe 26, the low-pressure pipe 25, the high-pressure delivery pipe 36, the high-pressure pipe 25a, and the high-pressure pump 40, and this control ends. Step S2 is an example of processing executed by the engine temperature determination unit. Note that "inside the high-pressure pump 40" refers to the portion of the high-pressure pump 40 that is filled with fuel. Specifically, the inside of the high-pressure pump 40 means the inside of the pressurizing chamber 43 , the suction passage 45 , the discharge passage 47 , and the relief passage 49 .

[0026] If the answer is Yes in step S2, the ECU 100 determines whether the ambient temperature around the engine 10 is higher than a second threshold value T2 based on the engine ambient temperature sensor 104 (step S3). The second threshold value T2 is set to an upper limit value of the ambient temperature around the cold engine 10 at which vapor is unlikely to be generated in any of the low-pressure delivery pipe 26, the low-pressure pipe 25, the high-pressure delivery pipe 36, the high-pressure pipe 25a, and the high-pressure pump 40. If the answer is No in step S3, it is considered that vapor is unlikely to be generated in the low-pressure delivery pipe 26, the low-pressure pipe 25, the high-pressure delivery pipe 36, the high-pressure pipe 25a, and the high-pressure pump 40, and this control ends. For example, when the hood of the hybrid vehicle 1 is opened, the ambient temperature around the engine 10 drops, promoting heat dissipation from the low-pressure pipe 25 and the high-pressure pipe 25a, and therefore vapor is unlikely to be generated. Step S3 is an example of processing executed by the ambient temperature determination unit.

[0027] If the answer is Yes in step S3, the ECU 100 determines whether the temperature difference between the low-pressure fuel and the high-pressure fuel is greater than a predetermined value D based on the fuel temperature sensors 29 and 39 (step S4). The predetermined value D is set to prevent hunting in the control, as will be described in detail later. If the answer is No in step S4, the low-pressure fuel and the high-pressure fuel are considered to be at approximately the same temperature, and this control ends.

[0028] If the answer to step S4 is Yes, the ECU 100 executes a temperature determination to determine whether the high-pressure fuel is hotter than the low-pressure fuel using the fuel temperature sensors 29 and 39 (step S5). Step S5 is an example of a process executed by the fuel temperature determination unit.

[0029] If the answer to step S5 is Yes, the ECU 100 reduces the port injection rate by a predetermined rate and increases the in-cylinder injection rate by the same rate (step S6). For example, the port injection rate is reduced by 10% and the in-cylinder injection rate is increased by 10%. This increases the injection amount of high-pressure fuel, which is hotter than low-pressure fuel, from the in-cylinder injection valve 37. As a result, new high-pressure fuel is supplied to the high-pressure pipe 25a, the high-pressure pump 40, and the high-pressure delivery pipe 36. This prevents the high-pressure fuel in the high-pressure delivery pipe 36, the high-pressure pipe 25a, and the high-pressure pump 40 from overheating, thereby suppressing the generation of vapor. Step S6 is an example of processing executed by the injection rate control unit.

[0030] If the answer is No in step S5, ECU 100 increases the port injection rate by a predetermined rate and decreases the in-cylinder injection rate by the same rate (step S7). For example, the port injection rate is increased by 10% and the in-cylinder injection rate is decreased by 10%. This increases the injection amount of low-pressure fuel, which is hotter than high-pressure fuel, from port injection valve 27. As a result, new low-pressure fuel is supplied to low-pressure delivery pipe 26 and low-pressure pipe 25. This prevents the low-pressure fuel in low-pressure delivery pipe 26 and low-pressure pipe 25 from overheating, thereby suppressing the generation of vapor. Step S7 is an example of processing executed by the injection rate control unit.

[0031] Next, the ECU 100 determines whether a predetermined time has elapsed since the execution of step S6 or S7 (step S8). If the answer is No in step S8, step S8 is executed again. If the answer is Yes in step S8, step S4 is executed again. That is, fuel injection is performed for a predetermined time at the in-cylinder injection rate and port injection rate set in step S6 or S7.

[0032] As described above, if the answer to steps S2 and S3 is Yes, steps S4 and subsequent steps are executed. Steps S2 and S3 determine whether environmental conditions under which vapor generation is possible exist. If the environmental conditions exist, it is assumed that vapor generation is possible, and steps S4 and subsequent steps are executed. Execution of steps S6 or S7 may result in a deterioration in fuel economy. Therefore, by making the environmental conditions of steps S2 and S3 true before executing steps S6 or S7, it is possible to avoid executing steps S6 or S7 carelessly when the possibility of vapor generation is not high. In this way, both a deterioration in fuel economy and the generation of vapor are suppressed.

[0033] The above-mentioned step S4 is executed to suppress control hunting, which occurs when the port injection rate and the in-cylinder injection rate are frequently switched in a short period of time. If step S4 is not executed, the port injection rate and the in-cylinder injection rate will be switched even if the temperature difference between the high-pressure fuel and the low-pressure fuel is slight. Step S8 is also executed to suppress control hunting.

[0034] In steps S4 and S5, the determinations are made based on the fuel temperature sensors 29 and 39, but this is not limiting. For example, the temperatures of the low-pressure fuel and the high-pressure fuel may be estimated without using a fuel temperature sensor. For example, the temperature of the low-pressure fuel in the low-pressure delivery pipe 26 may be estimated according to the operating state of the engine 10, taking into account the lengths and thermal conductivities of the low-pressure pipe 25 and the low-pressure delivery pipe 26. Similarly, the temperature of the high-pressure fuel in the high-pressure delivery pipe 36 may be estimated according to the operating state of the engine 10, taking into account the lengths and thermal conductivities of the high-pressure pipe 25a, the intake passage 45, and the discharge passage 47.

[0035] Although the embodiments of the present invention have been described in detail above, the present invention is not limited to such specific embodiments, and various modifications and variations are possible within the scope of the gist of the present invention as defined in the claims. [Explanation of symbols]

[0036] 1 Hybrid vehicle 10 Engine 26 Low pressure delivery pipe 27 port injection valve 36 High-pressure delivery pipe 37 In-cylinder injection valve 61 First motor (motor) 90 Battery 100 ECU (controller, external power supply determination unit, fuel temperature determination unit, injection rate control unit, engine temperature determination unit, ambient temperature determination unit)

Claims

1. an engine serving as a driving power source, the engine including a port injection valve, an in-cylinder injection valve, a low-pressure delivery pipe that supplies low-pressure fuel to the port injection valve, a low-pressure pipe that supplies the low-pressure fuel to the low-pressure delivery pipe, a high-pressure delivery pipe that supplies high-pressure fuel that is higher in pressure than the low-pressure fuel to the in-cylinder injection valve, and a high-pressure pipe and a high-pressure pump that supply the high-pressure fuel to the high-pressure delivery pipe; a motor that is a driving power source and that can generate electricity based on the power of the engine; A control device for a hybrid vehicle comprising: an injection rate control unit that controls a port injection rate, which is a ratio of fuel injection from the port injection valve to a total fuel injection amount from the port injection valve and the direct injection valve, and an direct injection rate, which is a ratio of the fuel injection amount from the direct injection valve to the total fuel injection amount; an external power supply determination unit that determines whether or not a vehicle-stop external power supply process is being executed, in which the motor generates power using power from the engine while the vehicle is stopped and supplies power to the outside; a fuel temperature determination unit that, when a positive determination is made by the external power supply determination unit, performs a temperature determination to determine whether the high-pressure fuel is hotter than the low-pressure fuel, When the external power supply determination unit and the fuel temperature determination unit make positive determinations, the injection rate control unit decreases the port injection rate and increases the in-cylinder injection rate more than when the external power supply determination unit makes a negative determination; When the external power supply determination unit makes a positive determination and the fuel temperature determination unit makes a negative determination, the injection rate control unit increases the port injection rate and decreases the in-cylinder injection rate more than when the external power supply determination unit makes a negative determination.

2. an engine temperature determination unit that determines whether the temperature of the engine is higher than a first threshold; an ambient temperature determination unit that determines whether the ambient temperature around the engine is higher than a second threshold value, 2. The control device for a hybrid vehicle according to claim 1, wherein when the external power supply determining unit, the engine temperature determining unit, and the ambient temperature determining unit make a positive determination, the fuel temperature determining unit executes the temperature determination.

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