Hybrid vehicle control device

Abstract

To prevent a feeling of strangeness from being given to a driver during execution of partial cylinder fuel-cut control.SOLUTION: A control device of a hybrid vehicle, which controls an engine, a first motor and a second motor of a hybrid vehicle which is equipped with the engine with a plurality of cylinders, an exhaust gas purification unit having a catalysis for purifying exhaust gas from the engine, the first motor, a planetary gear whose three rotational elements are connected to three shafts of the engine, the first motor and a driving shaft connected to a driving wheel and the second motor connected to the driving shaft, executes partial cylinder fuel-cut control by which fuel supply to at least one cylinder of the plurality of cylinders is stopped, and makes a rotation speed of the engine during execution of the partial cylinder fuel-cut control higher than that when the vehicle is travelling in the same travelling state and the partial cylinder fuel-cut control is not executed, on the basis of the travelling state of the hybrid vehicle.SELECTED DRAWING: Figure 2

Description

Technical Field

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

Background Art

[0002] Conventionally, as a control device for this type of hybrid vehicle, a control device for an engine and first and second motors of a hybrid vehicle including an engine having a plurality of cylinders, an exhaust gas purification device having a catalyst for purifying exhaust gas from the engine, and first and second motors has been proposed (see, for example, Patent Document 1). In this device, during the execution of partial cylinder fuel cut (partial cylinder FC) control for stopping the fuel supply to at least one cylinder among a plurality of cylinders, the engine speed is increased compared to when the partial cylinder FC control is not being executed. Thereby, deterioration of drivability during the partial cylinder FC control is suppressed.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the above-described control device for a hybrid vehicle, during the execution of partial cylinder FC control, the engine speed is increased compared to when the partial cylinder FC control is not being executed regardless of the running state of the hybrid vehicle. Therefore, depending on the running state of the hybrid vehicle, it may give the driver a sense of discomfort.

[0005] The control device for a hybrid vehicle of the present invention aims to suppress giving the driver a sense of discomfort during the execution of partial cylinder fuel cut control.

Means for Solving the Problems

[0006] The control device for a hybrid vehicle according to the present invention has adopted the following means in order to achieve the above-mentioned main object.

[0007] The control device for a hybrid vehicle according to the present invention is a control device for a hybrid vehicle that controls the engine and the first and second motors of a hybrid vehicle including an engine having a plurality of cylinders, an exhaust gas purification device having a catalyst for purifying exhaust gas from the engine, a first motor, and a planetary gear in which three rotating elements are connected to three axes of a drive shaft connected to the engine, the first motor, and drive wheels, and a second motor connected to the drive shaft, executes partial cylinder fuel cut control for stopping fuel supply to at least one cylinder among the plurality of cylinders, and during the execution of the partial cylinder fuel cut control, based on the running state of the hybrid vehicle, increases the rotational speed of the engine compared to when in the same running state and the partial cylinder fuel cut control is not being executed. This is the gist.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Modes for Carrying Out the Invention

[0009] Next, modes for carrying out the present invention will be described using examples.

Examples

[0010] FIG. 1 is a configuration diagram showing an overview of the configuration of a hybrid vehicle 20 equipped with a control device as an example of the present invention. As shown in the figure, the hybrid vehicle 20 includes an engine 22, an exhaust gas purification device (purification device) 24, a planetary gear 30, motors MG1 and MG2 (first and second motors), inverters 41 and 42, a battery 50, a transmission (transmission device) 60, and an electronic control unit (hereinafter referred to as "ECU") 70. The engine 22 is configured as an internal combustion engine and is operationally controlled by the ECU 70. The exhaust gas purification device 24 includes a catalyst for purifying exhaust gas containing carbon monoxide (CO) and hydrocarbons (HC) and a catalyst composed of an oxygen storage catalyst for storing oxygen in the exhaust gas. The planetary gear 30 is configured as a single pinion type planetary gear mechanism. The rotor of the motor MG1 is connected to the sun gear, the input shaft 33 of the transmission 60 is connected to the ring gear, and the crankshaft 23 of the engine 22 is connected to the carrier. The motors MG1 and MG2 are configured as, for example, synchronous generator motors, and the motor MG2 is connected to the input shaft 33. The inverters 41 and 42 are used to drive the motors MG1 and MG2 and are connected to the battery 50 via the power line 54. The motors MG1 and MG2 are rotationally driven by the ECU 70 by switching control of a plurality of switching elements (not shown) of the inverters 41 and 42. The battery 50 is configured as a secondary battery and is managed by the ECU 70. The transmission 60 is configured as, for example, a 10-speed stepped transmission, is connected to the input shaft 33 and the drive shaft 36 connected to the drive wheels 39a and 39b via a differential gear 38, and is controlled by the ECU 70. The ECU 70 includes, although not shown, a microcomputer having a CPU, a ROM, a RAM, a flash memory, an input / output port, and a communication port. Signals from various sensors are input to the ECU 70 via the input port.As signals input to the ECU 70, for example, there may be signals from various sensors necessary for controlling the operation of the engine 22, rotational positions θm1 and θm2 from a rotational position sensor (not shown) that detects the rotational positions of the rotors of the motors MG1 and MG2, detection values from sensors that detect the running state of the vehicle (for example, the accelerator opening Acc from a sensor that detects the opening of the accelerator pedal and the vehicle speed V from a vehicle speed sensor that detects the vehicle speed), etc., signals from various sensors necessary for driving and controlling the motors MG1 and MG2, signals from various sensors necessary for managing the battery 50, and a switch signal from a switch SW that is turned on when there is a request for partial cylinder fuel cut (partial cylinder FC) control (partial cylinder FC request) described later. From the ECU 70, various control signals for controlling the operation of the engine 22, switching control signals to a plurality of switching elements (not shown) of the inverters 41 and 42, and a shift control signal to the transmission 60 are output via the output ports.

[0011] In the hybrid vehicle 20 of the embodiment configured in this way, under the control of the ECU 70, it travels in a hybrid driving (HV driving) mode that involves driving the engine 22 or an electric driving (EV driving) mode that involves driving with the engine 22 stopped. For example, in the HV driving mode, the ECU 70 basically executes first control for driving and controlling the engine 22 and the motors MG1 and MG2 so that the engine 22 runs efficiently at a rotational speed equal to or higher than the lower limit rotational speed Nemin. In the first control, the lower limit rotational speed Nemin is set to a rotational speed predetermined as the lower limit value of the rotational speed at which the engine 22 does not misfire. In the control of the transmission 60, the ECU 70 sets the target gear stage M* of the transmission 60 based on the accelerator opening Acc, the vehicle speed V, and the shift diagram. When the current gear stage M of the transmission 60 matches the target gear stage M*, the ECU 70 controls the transmission 60 so that the gear stage M is maintained. When the gear stage M and the target gear stage M* are different, the ECU 70 executes shift control (upshift or downshift) for controlling the transmission 60 so that the gear stage M matches the target gear stage M*. The shift diagram will be described later. When it is required to raise the temperature of the exhaust gas purification device 24 during the load operation of the engine 22, the ECU 70 displays this fact on a display (not shown) near the driver's seat. When the switch SW is turned on, the ECU 70 executes partial cylinder fuel cut (partial cylinder FC) control for stopping the fuel supply to at least one of the plurality of cylinders. By executing such partial cylinder FC control, more air is supplied by the exhaust gas purification device 24 to raise the temperature in a low temperature environment.

[0012] Next, the operation of the hybrid vehicle 20 configured in this way, particularly the operation during traveling in the HV driving mode, will be described. FIG. 2 is a flowchart showing an example of a control routine executed by the ECU 70. This routine is executed at predetermined intervals (for example, every few msec) during traveling in the HV driving mode and when the engine 22 is under load operation.

[0013] When this routine is executed, the ECU 70 determines whether the switch SW is on, that is, whether there is a partial cylinder FC request (step S100). When the switch SW is off, the ECU 70 determines that there is no partial cylinder FC request and executes normal control (step S110). When the switch SW is on, the ECU 70 determines that there is a partial cylinder FC request, executes partial cylinder FC time control (step S120), and ends this routine. In the normal control in step S110, for the engine 22, the motors MG1, and MG2, the above-described first control is executed, and for the transmission 60, control is performed using the solid and broken shift lines in the shift diagram shown in FIG. 3.

[0014] In the partial cylinder FC time control in step S120, for the transmission 60, control is performed using the dash-dotted shift line in the shift diagram shown in FIG. 3. The dash-dotted shift line is set so that a lower speed gear can be selected than the solid and broken shift lines at the same vehicle speed V and accelerator opening Acc. In FIG. 3, only the shift lines from the first speed to the fourth speed are shown, but for the shift lines from the fifth speed to the tenth speed, they are also set so that a lower speed gear can be selected than the solid and broken shift lines at the same vehicle speed V and accelerator opening Acc.

[0015] In the partial cylinder FC time control of step S120, for the engine 22, the motor MG1, and the motor MG2, instead of the first control, the second control is executed. In the second control, first, a temporary target engine speed Netmp of the engine 22 is set using the vehicle speed V, the target gear position M*, and the rotation speed setting map for the second control. In the rotation speed setting map for the second control, the temporary target engine speed Netmp is set such that it linearly increases as the vehicle speed V increases at each gear position, and the slope with respect to the vehicle speed V decreases as the gear position increases. As a result, when the engine 22 is operated at the temporary target engine speed Netmp, the engine speed Ne of the engine 22 increases as the vehicle speed V increases at each gear position of the transmission 60, the engine speed Ne of the engine 22 decreases when the gear position is upshifted, and the engine speed Ne of the engine 22 increases when the gear position is downshifted. Thereby, the behavior of the engine speed Ne of the engine 22 can be made closer to the behavior of the engine mounted on an automobile equipped with an engine and a stepped transmission, and the discomfort of the driver can be suppressed. By setting the temporary target engine speed Netmp in this way, the temporary target engine speed Netmp becomes higher than that using the solid line or the broken line shift line in the shift diagram shown in FIG. 3. As a result, when the engine 22 is operated at the temporary target engine speed Netmp, there are more opportunities to make the cycle of the torque fluctuation of the engine 22 higher than the resonance frequency band of the drive system, the vibration of the vehicle can be suppressed, and the discomfort of the driver can be suppressed. When the ECU 70 sets the temporary target engine speed Netmp of the engine 22, the lower limit engine speed Nemin of the engine 22 is set higher than the first control, higher when the accelerator opening Acc is high than when it is low, and higher when the vehicle speed V is high than when it is low. The larger value of the temporary target engine speed Netmp and the lower limit engine speed Nemin is set as the target engine speed Ne* of the engine 22, and the target power Pe* of the engine 22 is set so that the vehicle travels with the driving power based on the accelerator opening Acc and the vehicle speed V. The engine 22 is operated with the target torque Te* obtained by dividing the target power Pe* by the target engine speed Ne* and the target engine speed Ne*, and the engine 22 and the motors MG1, MG2 are drive-controlled so that the vehicle travels with the driving torque Td*.By setting the lower limit rotational speed Nemin to be higher when the accelerator opening Acc is high than when it is low, and higher when the vehicle speed V is high than when it is low in this way, the behavior of the rotational speed Ne of the engine 22 can be made closer to the behavior of the engine mounted on an automobile equipped with an engine and a stepped transmission, and the discomfort of the driver can be suppressed.

[0016] According to the hybrid vehicle 20 equipped with the control device of the embodiment described above, a partial cylinder FC control for stopping the fuel supply to at least one cylinder among a plurality of cylinders is executed. During the execution of the partial cylinder FC control, by using the accelerator opening Acc, the vehicle speed V, and the dashed-dotted shift line in the shift diagram shown in FIG. 3, the rotational speed Ne of the engine 22 is increased compared to the first control in which the partial cylinder FC control is not executed at the same accelerator opening Acc and vehicle speed V, thereby suppressing giving discomfort to the driver during the execution of the partial cylinder FC time control.

[0017] In the hybrid vehicle 20 equipped with the control device of the embodiment, in the second control of the partial cylinder FC time control, by using the dashed-dotted shift line in the shift diagram shown in FIG. 3 or making the lower limit rotational speed Nemin higher, the rotational speed Ne of the engine 22 is made higher compared to when the first control is executed at the same accelerator opening Acc and vehicle speed V. Together with using the dashed-dotted shift line in the shift diagram shown in FIG. 3 and the lower limit rotational speed Nemin, or instead of at least one of the dashed-dotted shift line in the shift diagram shown in FIG. 3 and the lower limit rotational speed Nemin, by increasing the slope of the temporary target rotational speed Netmp with respect to the vehicle speed V in the rotational speed setting map for the second control, or by prohibiting shifting to a higher gear for each vehicle speed, the rotational speed Ne of the engine 22 may be made higher compared to the first control at the same accelerator opening Acc and vehicle speed V.

[0018] As described above, the embodiments for the mode for carrying out the present invention have been described using examples. However, the present invention is not limited to such examples, and it goes without saying that the present invention can be implemented in various forms without departing from the gist of the present invention.

Industrial Applicability

[0019] The present invention can be used in the manufacturing industry of hybrid vehicles and the like.

Explanation of Signs

[0020] 20 Hybrid vehicle, 70 Electronic control unit (ECU).

Claims

【Claim 1】 A control device for a hybrid vehicle, comprising: an engine having a plurality of cylinders; an exhaust gas purification device having a catalyst for purifying exhaust gas from the engine; a first motor; a planetary gear having three rotating elements connected to three axes of the engine, the first motor, and an input shaft; a second motor connected to the input shaft; and a stepped transmission connected to the input shaft and a drive shaft connected to drive wheels, the control device controlling the engine, the first and second motors, and the stepped transmission, executing partial cylinder fuel cut control for stopping fuel supply to at least one cylinder among the plurality of cylinders, when the partial cylinder fuel cut control is being executed, for the stepped transmission, controlling the stepped transmission so as to be in a lower gear stage than when the partial cylinder fuel cut control is not being executed at the same vehicle speed and accelerator opening; for the engine and the first and second motors, setting a temporary target rotational speed such that the higher the vehicle speed, the larger and more linear it becomes, and the higher the gear stage of the stepped transmission, the smaller the slope with respect to the vehicle speed; setting a lower limit rotational speed to be higher than a lower limit value of a rotational speed at which the engine does not misfire, higher when the accelerator opening is high than when it is low, and higher when the vehicle speed is high than when it is low; setting the larger of the temporary target rotational speed and the lower limit rotational speed as the target rotational speed of the engine; setting a target power of the engine such that the hybrid vehicle travels with a driving power based on the accelerator opening and the vehicle speed; and controlling such that the engine is operated at the target rotational speed and the hybrid vehicle travels with a driving torque by dividing the target power by the target rotational speed, A control device for a hybrid vehicle.

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