Control device of hybrid vehicle

Abstract

To cool an exhaust catalyst of a hybrid vehicle without controlling the increase in amount of fuel injection.SOLUTION: A hybrid vehicle 1 comprises an engine 11 and a motor 13 as a driving source. The engine 11 contains a fuel injector 44, an intake passage 41, an exhaust passage 42 and an exhaust catalyst 43. The engine 11 and the motor 13 make it possible to drive and connect via a clutch mechanism 12c. An electronic control device (ECU) 30 executes motoring by driving and connecting the engine 11 and the motor 13 by the clutch mechanism 12c and at the same time by driving the motor 13 if catalyst simulation temperature TCS calculated according to the operational state of the engine 11 is a first reference temperature or more. In addition, the ECU 30 stops the motoring if the calculated catalyst simulation temperature TCS is a second reference temperature or less.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The technology disclosed in this specification relates to a control device for a hybrid vehicle equipped with an engine and a motor as power sources. [Background technology]

[0002] A known example of this type of technology is the "engine fuel injection control device" described in Patent Document 1 below. In this technology, in order to prevent damage due to overheating of the exhaust catalyst, which is one of the exhaust system components, the amount of fuel injected into the engine is increased to cool the exhaust catalyst when the exhaust temperature exceeds a second threshold value that is higher than a first threshold value, and cooling the exhaust catalyst by increasing the amount of fuel injected is prohibited when the exhaust temperature is lower than the first threshold value. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2003-65111 Summary of the Invention [Problem to be solved by the invention]

[0004] However, if future exhaust gas regulations prohibit increasing the fuel injection amount, it will not be possible to adopt the technology described in Patent Document 1 for cooling the exhaust catalyst. Since hybrid vehicles that use exhaust catalysts also have similar issues, it is desirable to provide an alternative means for cooling the exhaust catalyst.

[0005] This disclosed technology has been developed in consideration of the above circumstances, and its purpose is to provide a control device for a hybrid vehicle that makes it possible to cool the exhaust catalyst of a hybrid vehicle without performing control to increase the fuel injection amount. [Means for solving the problem]

[0006] In order to achieve the above object, the technology described in claim 1 is a control device for a hybrid vehicle having an engine and a motor as power sources, wherein the engine includes a fuel supply means for supplying fuel to the engine, an intake passage for introducing intake air into the engine, an exhaust passage for discharging exhaust gas after combustion from the engine, and an exhaust catalyst provided in the exhaust passage for purifying the exhaust gas, the engine and the motor are configured to be driveably connected via a clutch mechanism, and includes a simulated temperature calculation means for calculating a simulated temperature of the exhaust catalyst, and a motoring control means for controlling the motor and the clutch mechanism to perform engine motoring, and the motoring control means performs motoring by drive-connecting the engine and the motor via the clutch mechanism and driving the motor when the calculated simulated temperature is equal to or higher than a first reference temperature.

[0007] According to the configuration of the above technology, when the simulated temperature of the exhaust catalyst becomes high enough to be equal to or higher than the first reference temperature, motoring is performed. As a result, the engine and the motor are drivingly connected by the clutch mechanism, and the engine is driven to rotate by the motor. Therefore, as the engine drives to rotate, intake air (fresh air) flows into the intake passage, and the fresh air is sent to the exhaust catalyst in the exhaust passage via the engine, removing heat from the exhaust catalyst.

[0008] In order to achieve the above object, the technology described in claim 2 is the technology described in claim 1, further comprising an acceleration request value detection means for detecting an acceleration request value for the hybrid vehicle from the driver, and the motoring control means cuts off the supply of fuel by the fuel supply means and performs motoring when the simulated temperature is equal to or higher than a first reference temperature and the detected acceleration request value is smaller than a predetermined reference value.

[0009] According to the configuration of the above technology, in addition to the effect of the technology described in claim 1, when the simulated temperature is equal to or higher than the first reference temperature and the acceleration request value is smaller than a predetermined reference value, motoring is performed without supplying fuel to the engine. Therefore, during motoring, fuel is not burned in the engine and the exhaust gas after combustion is not sent to the exhaust catalyst.

[0010] In order to achieve the above object, the technology described in claim 3 is the technology described in claim 2, in which the motoring control means stops motoring when the calculated simulated temperature is equal to or lower than a second reference temperature and the detected acceleration request value is equal to or higher than a predetermined reference value.

[0011] According to the configuration of the above technology, in addition to the effect of the technology described in claim 2, when the simulated temperature of the exhaust catalyst falls to a temperature equal to or lower than the second reference temperature and there is an acceleration request whose acceleration request value is equal to or higher than a predetermined reference value, motoring stops and fresh air is no longer supplied to the exhaust catalyst, so the temperature of the exhaust catalyst does not drop excessively. [Effects of the Invention]

[0012] According to the technology recited in claim 1, the exhaust catalyst of a hybrid vehicle can be cooled with fresh air without performing control to increase the fuel injection amount.

[0013] According to the technology recited in claim 2, in addition to the effect of the technology recited in claim 1, the exhaust catalyst of the hybrid vehicle can be cooled with fresh air of even lower temperature.

[0014] According to the technology recited in claim 3, in addition to the effect of the technology recited in claim 1 or 2, it is possible to suppress a decrease in the purification capacity of the exhaust catalyst. [Brief explanation of the drawings]

[0015] [Figure 1] 1 is a schematic diagram showing a hybrid vehicle according to one embodiment; [Figure 2]FIG. 2 is a block diagram showing the configuration of a control unit according to an embodiment. [Figure 3] 4 is a flowchart showing the contents of motoring control according to one embodiment. [Figure 4] 4 is a flowchart showing the contents of fuel cut control according to one embodiment. [Figure 5] 4 is a time chart showing changes in various parameters when motoring control and fuel cut control are executed in one embodiment. [Figure 6] 6 is a time chart showing changes in various parameters when fuel increase control is executed, as a comparative example. DETAILED DESCRIPTION OF THE INVENTION

[0016] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A detailed description of an embodiment of a control device for a hybrid vehicle will be given below with reference to the accompanying drawings.

[0017] [About hybrid vehicles] An overview of the hybrid vehicle of this embodiment will be described. Fig. 1 shows a schematic diagram of a hybrid vehicle 1 of this embodiment. As shown in Fig. 1, the hybrid vehicle 1 is a vehicle equipped with an engine 11 and a motor 13 as power sources. The hybrid vehicle 1 is equipped with the engine 11, a transmission 12, a motor generator 13 (hereinafter referred to as "motor 13"), a battery 14, front wheels 21, rear wheels 22, and an electronic control unit (ECU) 30.

[0018] The engine 11 and the motor 13 are configured to be drivably connected via a transmission 12. The engine 11 is also a power source for the motor 13 and includes a crankshaft 11a. The crankshaft 11a is connected to an input shaft 12a of the transmission 12.

[0019] The engine 11 has a plurality of cylinders (not shown) and includes an intake passage 41 for introducing intake air into the engine 11, an exhaust passage 42 for discharging exhaust gas after combustion from the engine 11, an exhaust catalyst 43 provided in the exhaust passage 42 for purifying the exhaust gas, and an injector 44 for supplying fuel to the engine 11. The intake passage 41 is provided with a throttle valve 45 for adjusting the amount of intake air flowing through the passage 41. As is well known, fuel is supplied to the injector 44 from a fuel tank (not shown). The injector 44 and the fuel tank correspond to an example of a "fuel supply means" of the disclosed technology.

[0020] The transmission 12 is disposed between the engine 11 and the motor 13. The transmission 12 includes an input shaft 12a connected to the crankshaft 11a of the engine 11, an output shaft 12b connected to the motor 13, and a clutch mechanism 12c that couples and releases the coupling between the input shaft 12a and the output shaft 12b.

[0021] The motor 13 is located closer to the rear wheels 22 than the transmission 12. In other words, the motor 13 is located on the opposite side of the transmission 12 from the engine 11. The motor 13 is connected to a drive shaft 23. The motor 13 functions as a generator that generates mechanical power from electrical energy. The motor 13 also functions as a generator that generates electrical energy from mechanical energy.

[0022] That is, the motor 13 functions as a motor that generates power (i.e., mechanical power) for running the hybrid vehicle 1 using power (i.e., electrical energy) supplied from the battery 14. The motor 13 also functions as a generator that generates power (i.e., performs regenerative power generation) using rotational power (i.e., mechanical energy) transmitted from the rear wheels 22 via the drive shaft 23 or the like, and charges the power (i.e., electrical energy) into the battery 14.

[0023] The battery 14 is electrically connected to the motor 13. The battery 14 supplies power to the motor 13 to discharge the power, and receives power from the motor 13 to charge the power.

[0024] The front wheels 21 are driven wheels that rotate as the hybrid vehicle 1 travels. On the other hand, the rear wheels 22 are driving wheels that are connected to the motor 13 via an axle 24, a differential gear 25, and a drive shaft 23.

[0025] The ECU 30 constitutes a control unit that controls the components of the hybrid vehicle 1 (for example, the engine 11, the transmission 12, and the motor 13), and includes a central processing unit (CPU), various memories, an external input circuit, an external output circuit, and the like.

[0026] FIG. 2 is a block diagram showing the configuration of the control unit of this embodiment. As shown in FIG. 2, the ECU 30 includes an HV-ECU 31, an MG-ECU 32, and an EFI-ECU 33. The HV-ECU 31 controls the hybrid vehicle 1. The MG-ECU 32 controls the motor 13. The EFI-ECU 33 controls the engine 11. Detection signals from an accelerator sensor 51, a brake sensor 52, a weight sensor 53, and a seating sensor 54 are input to the HV-ECU 31. Detection signals from a rotation speed sensor 55 and an intake air amount sensor 56 are input to the EFI-ECU 33. Torque command data and torque output data are exchanged between the HV-ECU 31 and the MG-ECU 32. Detection signals from the various sensors 51 to 56 are exchanged between the HV-ECU 31 and the EFI-ECU 33.

[0027] Here, the accelerator sensor 51 is a sensor that detects an accelerator opening degree ACCP, which is an operation amount by the driver of an accelerator pedal (not shown) provided at the driver's seat of the hybrid vehicle 1. That is, the accelerator sensor 51 is for detecting an acceleration value required by the driver for the hybrid vehicle 1, and corresponds to an example of an "acceleration request value detecting means" in the disclosed technology. The accelerator opening degree ACCP corresponds to an example of an "acceleration request value" in the disclosed technology. The brake sensor 52 is a sensor that detects an operation by the driver of a brake pedal (not shown) provided at the driver's seat. The weight sensor 53 is a sensor that is attached to a loading platform (not shown) of the hybrid vehicle 1 and detects the weight of a load in the loading platform. The seat sensor 54 is a sensor that is attached to the passenger compartment (e.g., a seat) of the hybrid vehicle 1 and detects the weight (body weight) of a passenger (including the driver) in the passenger compartment. The rotation speed sensor 55 is a sensor that detects the rotation speed of the crankshaft 11a of the engine 11 as an engine rotation speed NE. The intake air amount sensor 56 is a sensor that detects the amount of intake air flowing through the intake passage 41 .

[0028] As will be described later, the ECU 30, the rotation speed sensor 55, and the intake air amount sensor 56 correspond to an example of a "simulated temperature calculation means" of the disclosed technology for calculating a simulated temperature (catalyst simulated temperature) TSC of the exhaust catalyst 43. Also, as will be described later, the ECU 30 corresponds to an example of a "motoring control means" of the disclosed technology for controlling the motor 13 and the transmission 12 to perform motoring of the engine 11.

[0029] [About motoring control] Next, the motoring control performed in the hybrid vehicle 1 will be described.

[0030] 3 is a flowchart showing the motoring control executed by the ECU 30. When the process proceeds to this routine, the ECU 30 (HV-ECU 32) acquires the catalyst simulated temperature TCS in step 100.

[0031] Here, the ECU 30 (EFI-ECU 33) calculates the catalyst simulated temperature TCS in a separate processing routine (not shown) based on the operating state of the hybrid vehicle 1. That is, the ECU 30 applies the detected values ​​of the rotation speed sensor 55 and the intake amount sensor 56 to a predetermined calculation formula to calculate the temperature of the exhaust catalyst 43 at each time as the catalyst simulated temperature TCS.

[0032] Next, in step 110, ECU 30 determines whether catalyst simulated temperature TCS is equal to or higher than a "motoring start temperature TMS," which is a reference temperature for determining whether motoring should be started. Motoring start temperature TMS corresponds to an example of a "first reference temperature" in the disclosed technology. If the result of this determination is positive, ECU 30 proceeds to step 120, and if the result of this determination is negative, ECU 30 proceeds to step 150.

[0033] In step 120, the ECU 30 sets the motoring request flag FMR to "1."

[0034] Next, in step 130, the ECU 30 determines whether the engine stop request flag FESR is "1." This flag FESR is determined depending on the operating state of the hybrid vehicle 1, and is set by a separate "fuel cut control" processing routine, which will be described later. When the engine stop request flag FESR is "1," this means that the engine 11 is in a stopped state due to a fuel cut. If the determination result in step 130 is positive, the ECU 30 proceeds to step 140, and if the determination result is negative, the ECU 30 proceeds to step 170.

[0035] Then, in step 140, the ECU 30 performs motoring while the engine 11 is stopped, and temporarily ends the subsequent processing. In this embodiment, when the catalyst simulated temperature TCS is equal to or higher than the motoring start temperature TMS and there is a request to stop the engine 11, the ECU 30 performs motoring by drivingly connecting the engine 11 and the motor 13 with the clutch mechanism 12c and driving the motor 13.

[0036] On the other hand, moving from step 110 to step 150, ECU 30 determines whether the catalyst simulated temperature TCS is equal to or lower than the "motoring stop temperature TME," which is a reference temperature for determining a motoring stop request. The motoring stop temperature TME corresponds to an example of the "second reference temperature" in this disclosed technology. If the result of this determination is positive, ECU 30 proceeds to step 160, and if the result of this determination is negative, ECU 30 jumps to step 120.

[0037] Then, in step 160, the ECU 30 sets the motoring request flag FMR to "0."

[0038] Next, in step 170, which follows from step 130 or step 160, the ECU 30 determines whether motoring is being performed. If the result of this determination is positive, the ECU 30 proceeds to step 180, and if the result of this determination is negative, the ECU 30 temporarily terminates the subsequent processing.

[0039] Then, in step 180, the ECU 30 stops motoring and temporarily ends the subsequent processing.

[0040] [About fuel cut control] 4 is a flowchart showing the contents of the fuel cut control executed by the ECU 30. When the process proceeds to this routine, the ECU 30 takes in the accelerator opening ACCP detected by the accelerator sensor 51 in step 200.

[0041] Next, in step 210, the ECU 30 determines whether the accelerator opening ACCP is smaller than a predetermined reference opening ACC1. The reference opening ACC1 corresponds to, for example, the opening when the engine 11 is decelerating or stopped. The reference opening ACC1 corresponds to an example of the "reference value" in the disclosed technology. If the result of this determination is positive, the ECU 30 proceeds to step 220, and if the result of this determination is negative, the ECU 30 proceeds to step 240.

[0042] In step 220, the ECU 30 executes a fuel cut. That is, the ECU 30 cuts off the supply of fuel to the engine 11 by the injector 44. The ECU 30 also sets a fuel cut flag FFC to "1."

[0043] Next, in step 230, the ECU 30 sets the engine stop request flag FESR to "1" and temporarily ends the subsequent processing.

[0044] On the other hand, in step 240 following step 210, the ECU 30 sets the engine stop request flag FESR to "0" and temporarily ends the subsequent processing.

[0045] According to the motoring control and fuel cut control described above, when the calculated catalyst simulated temperature TCS is equal to or higher than the motoring start temperature TMS, the ECU 30 performs motoring by drivingly connecting the engine 11 and the motor 13 with the clutch mechanism 12c and driving the motor 13. More specifically, in this embodiment, when the catalyst simulated temperature TCS is equal to or higher than the motoring start temperature TMS, the ECU 30 performs motoring when the supply of fuel by the injector 44 is cut off (fuel cut). Furthermore, when the calculated catalyst simulated temperature TCS is equal to or lower than the motoring stop temperature TME, the ECU 30 stops motoring.

[0046] 5 is a time chart showing changes in various parameters when the motoring control and fuel cut control are executed to cool the exhaust catalyst 43 according to this embodiment. In FIG. 5, (A) represents the vehicle speed VS of the hybrid vehicle 1, (B) represents the catalyst simulated temperature TCS, (C) represents the fuel increase flag FIF for the fuel increase control, (D) represents the actual catalyst temperature TC, (E) represents the engine rotation speed NE, (F) represents the fuel cut flag FFC, (G) represents the motoring request flag FMR, and (H) represents the execution of motoring. In FIG. 5, at time t1, the engine 11 starts, and as the engine rotation speed NE begins to increase, the vehicle speed VS, the catalyst simulated temperature TCS, and the catalyst temperature TC also begin to increase.

[0047] Then, at time t2, when the rising catalyst simulated temperature TCS reaches the motoring start temperature TMS, the motoring request flag FMR becomes 1. Then, at time t3, fuel cut is performed, and when the fuel cut flag FFC becomes 1, motoring begins, and motoring continues until time t5.

[0048] Here, immediately after motoring begins, the vehicle speed VS, catalyst simulated temperature TCS, and catalyst temperature TC soon reach their peaks and begin to decrease. The engine speed NE also begins to decrease immediately before motoring begins, stops decreasing at time t4, and is then maintained at a predetermined speed until time t5. The speed at this time is the speed at which the engine 11 is driven by motoring, and can be set to, for example, 1000 to 1500 rpm.

[0049] Then, when the decreasing catalyst simulated temperature TCS reaches the motoring stop temperature TME at time t5 due to the execution of motoring, the motoring request flag FMR becomes "0", the execution of motoring stops, the engine 11 stops, and the engine speed NE becomes zero. At this point, it can be seen that the actual catalyst temperature TC drops to a temperature lower than that before the start of the engine 11. In the hybrid vehicle 1 of this embodiment, if the catalyst simulated temperature TCS exceeds a threshold value, motoring can be performed during deceleration to lower the catalyst temperature TC, thereby preparing for a rise in the catalyst temperature TC during re-acceleration.

[0050] In FIG. 5, the fuel increase control is not executed, and the fuel increase flag FIF remains at "0" between time t0 and time t5.

[0051] For comparison, Fig. 6 shows, in a time chart, changes in various parameters when fuel increase control is performed instead of motoring control to cool the exhaust catalyst. In Fig. 6, (A) to (F) show changes in vehicle speed VS, catalyst simulated temperature TCS, fuel increase flag FIF, catalyst temperature TC, engine speed NE, and fuel cut flag FFC, just like Fig. 5. In Fig. 6, when engine speed NE begins to increase at time t1, vehicle speed VS, catalyst simulated temperature TCS, and catalyst temperature TC also begin to increase.

[0052] Thereafter, at time t2, when the rising catalyst simulated temperature TCS reaches the fuel increase temperature TFI, the fuel increase flag FIF becomes "1" and fuel increase control is started. At time t3, when the engine stops, the engine speed NE becomes zero, and the fuel cut flag FFC becomes "1," the fuel increase control stops and the fuel increase flag FIF becomes "0."

[0053] After that (after time t3), the vehicle speed VS, catalyst simulated temperature TCS, and catalyst temperature TC decrease, but the actual catalyst temperature TC does not fall below the temperature before the engine was started, as shown in Figure 6. In this comparative hybrid vehicle, the engine is stopped during deceleration except under certain conditions, so the catalyst temperature cannot be lowered.

[0054] [About the operation and effects of the control device for hybrid vehicles] According to the configuration of the control device for a hybrid vehicle of this embodiment described above, motoring is performed when the catalyst simulated temperature TCS of the exhaust catalyst 43 becomes high enough to be equal to or higher than the motoring start temperature TMS. As a result, the engine 11 and the motor 13 are drivingly connected by the clutch mechanism 12c, and the engine 11 is rotationally driven by the motor 13. Therefore, as the engine 11 rotates, intake air (fresh air) flows into the intake passage 41, and the fresh air is sent to the exhaust catalyst 43 in the exhaust passage 42 via the engine 11, removing heat from the exhaust catalyst 43. Therefore, the exhaust catalyst 43 of the hybrid vehicle 1 can be cooled by fresh air without performing control to increase the fuel injection amount.

[0055] According to the configuration of this embodiment, when the catalyst simulated temperature TCS is equal to or higher than the motoring start temperature TMS and the accelerator opening ACCP is smaller than a predetermined reference opening ACC1, motoring is performed without supplying fuel to the engine 11. Therefore, during motoring, fuel is not burned in the engine 11, and the exhaust gas after combustion is not sent to the exhaust catalyst 43. This allows the exhaust catalyst 43 of the hybrid vehicle 1 to be cooled with even lower temperature fresh air.

[0056] According to the configuration of this embodiment, when the catalyst simulated temperature TCS of the exhaust catalyst 43 reaches a temperature equal to or lower than the motoring stop temperature TME, and there is an acceleration request that causes the accelerator opening ACCP to be equal to or greater than a predetermined reference opening ACC1, motoring stops and fresh air is no longer supplied to the exhaust catalyst 43. Therefore, the temperature of the exhaust catalyst 43 does not drop excessively. As a result, a decrease in the purification capacity of the exhaust catalyst 43 can be suppressed.

[0057] As described above, in this embodiment, the ECU 30 is capable of suppressing excessive temperature rise of the exhaust catalyst 43 by performing motoring when the hybrid vehicle 1 is decelerating or stopped after the catalyst simulated temperature TCS reaches or exceeds the threshold motoring start temperature TMS.

[0058] The disclosed technology is not limited to the above-described embodiment, and part of the configuration can be appropriately modified within the scope of the disclosed technology. [Industrial Applicability]

[0059] The disclosed technology can be applied to a hybrid vehicle equipped with an engine having an exhaust catalyst in the exhaust passage. [Explanation of symbols]

[0060] 1 Hybrid vehicle 11 Engine 12c clutch mechanism 13 Motor 14 Battery 30 ECU (one element of simulated temperature calculation means, motoring control means) 41 Intake passage 42 Exhaust passage 43 Exhaust catalyst 44 injector (fuel supply means) 51 Accelerator sensor (acceleration request detection means) 55 Rotational speed sensor (one element of simulated temperature calculation means) 56 Intake air volume sensor (one element of simulated temperature calculation means) TCS catalyst simulation temperature TMS Motoring start temperature (first reference temperature) TME Motoring stop temperature (second reference temperature) ACCP Accelerator opening (acceleration demand value) ACC1 reference opening (reference value)

Claims

1. A control device for a hybrid vehicle equipped with an engine and a motor as power sources, the engine includes a fuel supply means for supplying fuel to the engine, an intake passage for introducing intake air into the engine, an exhaust passage for discharging exhaust gas after combustion from the engine, and an exhaust catalyst provided in the exhaust passage for purifying the exhaust gas, The engine and the motor are configured to be drivably connected via a clutch mechanism, a simulated temperature calculation means for calculating a simulated temperature of the exhaust catalyst; a motoring control means for controlling the motor and the clutch mechanism to perform motoring of the engine; When the calculated simulated temperature is equal to or higher than a first reference temperature, the motoring control means performs the motoring by drivingly connecting the engine and the motor with the clutch mechanism and driving the motor. A control device for a hybrid vehicle.

2. 2. The control device for a hybrid vehicle according to claim 1, The hybrid vehicle further includes an acceleration demand value detection means for detecting an acceleration demand value of a driver of the hybrid vehicle, When the simulated temperature is equal to or higher than a first reference temperature and the detected acceleration request value is smaller than a predetermined reference value, the motoring control means cuts off the supply of fuel by the fuel supply means and executes the motoring. A control device for a hybrid vehicle.

3. 3. The hybrid vehicle control device according to claim 2, The motoring control means stops the motoring when the calculated simulated temperature is equal to or lower than a second reference temperature and the detected acceleration request value is equal to or higher than a predetermined reference value. A control device for a hybrid vehicle.

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