Vehicle control device

Abstract

To suppress deterioration of fuel efficiency in a vehicle control device for a hybrid vehicle mounted on a starting clutch.SOLUTION: An ECU (100) executes catalyst warming control to maintain a clutch (40) in a slipped state by operating an internal combustion engine (10) while keeping a rotation speed thereof at a constant value by controlling a motor (30) and by controlling a transmission ratio of a mechanical transmission (50). During the catalyst warming control, the ECU controls a main motor and sub-motor (90) so that larger driving torque is generated on a main drive shaft (60) than a sub-drive shaft (80).SELECTED DRAWING: Figure 1

Description

[Technical Field]

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

[0002] A conventional hybrid vehicle includes an internal combustion engine with a catalyst in an exhaust passage, an electric motor, an engine disengagement clutch interposed between the internal combustion engine and the electric motor, a transmission that transmits torque to drive wheels, and a launch clutch interposed between the electric motor and the transmission. A conventional control device applied to this hybrid vehicle executes catalyst warm-up control when catalyst warm-up is required. That is, the conventional control device controls the electric motor to maintain a constant engine speed, and controls the transmission to reduce the launch clutch output shaft rotation speed (i.e., the transmission input shaft rotation speed) to maintain the launch clutch in a slip state (partially engaged state), thereby transmitting torque corresponding to the driver's requested driving torque to an axle connected to the transmission output shaft (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2016-37251 Summary of the Invention

[0004] When the driver's required driving torque increases, the engine torque generated by the internal combustion engine is increased. Furthermore, if the engine torque is insufficient to generate torque corresponding to the required driving torque, the motor torque generated by the motor is increased. However, with conventional control systems, the starting clutch is maintained in a slip state during catalyst warm-up control, causing clutch loss. This can lead to a problem in that torque corresponding to the required driving torque cannot be generated even when the motor torque is maximized. Furthermore, clutch loss is determined by the product of the difference between the input shaft rotation speed and the output shaft rotation speed of the clutch (hereinafter sometimes referred to as the "clutch rotational speed difference") and the clutch transmission torque. However, if the motor torque is increased in response to an increase in the required driving torque during catalyst warm-up control, the clutch transmission torque also increases, resulting in a problem of reduced fuel economy. The present invention was made to address this problem.

[0005] One aspect of the vehicle control device of the present invention is The invention is applied to a hybrid vehicle (HV) including an internal combustion engine (10) having a catalyst (11) in an exhaust passage, a main motor (30) having a rotating shaft connected to the internal combustion engine so as to be able to transmit power, a mechanical transmission (50) connected to a main drive shaft (60) having wheels (61R, 61L) attached to both ends so as to be able to transmit power, a clutch (40) having an input shaft connected to the rotating shaft of the main motor (30) and an output shaft connected to the input shaft of the mechanical transmission (50), and an auxiliary motor (90) connected to an auxiliary drive shaft (80) having wheels (81R, 81L) attached to both ends so as to be able to transmit power.

[0006] This vehicle control device If a request for warming up the catalyst has been issued (S205: Yes), the main motor is driven and the internal combustion engine is operated so that the rotation speed of the internal combustion engine becomes a constant predetermined rotation speed (S230), Controlling the speed ratio achieved by the mechanical transmission so that the rotational speed of the input shaft of the mechanical transmission is lower than the rotational speed of the input shaft of the clutch (S240); maintaining the clutch in a slip state when the rotation speed of the input shaft of the mechanical transmission is lower than the rotation speed of the input shaft of the clutch (S235); Catalyst warm-up control is performed, When the catalyst warm-up control is being executed, the main motor and the auxiliary motor are controlled so that the ratio of the drive shaft torque distributed to the auxiliary drive shaft to the drive torque distributed to the main drive shaft is larger than when the catalyst warm-up control is not being executed (S220, S250).

[0007] According to this, during catalyst warm-up control, the auxiliary motor generates a large motor torque relative to the main motor, so that a drive torque that satisfies the user's drive torque requirement can be applied to the vehicle without increasing the motor torque generated by the main motor. Furthermore, since the motor torque generated by the main motor can be relatively reduced during catalyst warm-up control, the clutch transmission torque becomes relatively small. Therefore, clutch loss becomes relatively small, and fuel economy is less likely to deteriorate. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a schematic configuration diagram of a vehicle and a vehicle control device according to an embodiment of the present invention; [Figure 2] Routine executed by the CPU of the electronic control unit shown in Figure 1 [Figure 3] A time chart for explaining the operation of the vehicle control device shown in FIG. DETAILED DESCRIPTION OF THE INVENTION

[0009] A vehicle control device according to an embodiment of the present invention is applied to a hybrid vehicle (HV) having the components shown in Fig. 1. The internal combustion engine 10 is a gasoline fuel-injected internal combustion engine, and is provided with a three-way catalyst 11 in its exhaust passage. The engine 10 is provided with actuators (not shown, for example, a fuel injection valve, an ignition device, and a throttle valve drive motor), and is controlled by an ECU 100, which will be described later. The crankshaft of the engine 10 is connected to the input shaft of an engine disconnection clutch 20, which is controlled by the ECU 100 to be in either an engaged state or a disengaged state. The output shaft of the engine disconnection clutch 20 is connected to the rotating shaft of a main motor (generator-motor) 30.

[0010] In response to commands from the ECU 100, the first inverter 31 converts DC power from the battery 70 into three-phase AC power and supplies it to the main motor 30, and converts the three-phase AC power from the main motor 30 into DC power and supplies it to the battery 70. The rotating shaft of the main motor 30 is connected to the input shaft of the starting clutch 40.

[0011] The output shaft of the starting clutch 40 is connected to the input shaft of the mechanical transmission 50. The starting clutch 40 is controlled by the ECU 100 to be in one of an engaged state, a disengaged state, and a slip state (half-engaged state).

[0012] The mechanical transmission 50 realizes one of the first through sixth gears and a reverse gear in response to a command from the ECU 100. More specifically, when an operating point formed by the vehicle speed SPD and the accelerator pedal depression amount AP crosses a known shift line during normal shift control, the ECU 100 controls the mechanical transmission 50 so as to realize the shift line indicated by the shift line crossed by the operating point. However, when a request for warming up the catalyst 11 is generated, the ECU 100 controls the mechanical transmission 50 by executing a catalyst warm-up shift control, which will be described later. The mechanical transmission 50 may be a continuously variable transmission (CVT). The output shaft of the mechanical transmission 50 is connected to a main drive shaft 60 via a differential gear 51 so as to be able to transmit power. A right front wheel 61R and a left front wheel 61L are attached to both ends of the main drive shaft 60.

[0013] A right rear wheel 81R and a left rear wheel 81L are attached to both ends of the auxiliary drive shaft 80. The auxiliary drive shaft 80 is connected to the rotary shaft of the auxiliary motor 90. Therefore, the auxiliary motor 90 rotates the auxiliary drive shaft 80 and is also rotated by the auxiliary drive shaft 80. In response to commands from the ECU 100, the second inverter 91 converts DC power from the battery 70 into three-phase AC power and supplies it to the auxiliary motor 90, and converts the three-phase AC power from the auxiliary motor 90 into DC power and supplies it to the battery 70.

[0014] The ECU 100 is an electronic control unit equipped with a microcomputer including a CPU, a ROM, a RAM, a nonvolatile memory, etc., and acquires output values ​​(detected values) of the following sensors. An accelerator pedal operation amount sensor 101 detects an accelerator pedal operation amount AP. A water temperature sensor 102 detects the temperature (cooling water temperature) THW of the cooling water of the engine 10. A vehicle speed sensor 103 detects a vehicle speed SPD, which is the rotation speed NMA of the main drive shaft 60. A rotation speed sensor 104 detects the engine rotation speed NE, which is the rotation speed of the crankshaft of the engine 10 (the rotation speed of the input shaft of the engine disconnecting clutch 20). A rotational speed sensor 105 for detecting the input shaft rotational speed NATin of the mechanical transmission 50. A rotation speed sensor 106 for detecting the rotation speed NSA of the auxiliary drive shaft 80.

[0015] (Activation) The CPU of the ECU 100 executes the routine shown in the flowchart of Fig. 2 every time a predetermined time elapses. Therefore, at the predetermined timing, the CPU starts processing from step (hereinafter referred to as "S") 200 in Fig. 2 and proceeds to S205.

[0016] In S205, the CPU determines whether or not a warm-up request has been generated for the catalyst 11. More specifically, the CPU determines that a warm-up request has been generated for the catalyst 11 when the coolant temperature THW is equal to or lower than the threshold coolant temperature THWth. The CPU may also determine that a warm-up request has been generated for the catalyst 11 when the elapsed time since the start of the engine 10 is within a predetermined time and the estimated catalyst temperature Tc is equal to or lower than a predetermined estimated temperature threshold Tcth.

[0017] If a warm-up request for the catalyst 11 has not been generated, the CPU proceeds from S205 to S210 and executes normal shift control. That is, the CPU controls the gear position of the mechanical transmission 50 based on the above-mentioned shift diagram. Next, the CPU proceeds to S215 and sets the engine disengagement clutch 20 to an engaged state or a disengaged state depending on the driver's required driving torque Tqreq. That is, if the required driving torque Tqreq is smaller than the threshold torque, the CPU sets the engine disengagement clutch 20 to a disengaged state. If the required driving torque Tqreq is equal to or greater than the threshold torque, the CPU sets the engine disengagement clutch 20 to an engaged state. In addition, the CPU sets the start clutch 40 to an engaged state in S215.

[0018] The CPU separately calculates the required driving torque Tqreq by applying the accelerator pedal operation amount AP and the vehicle speed SPD to a look-up table MapTqreq(AP, SPD).

[0019] Next, the CPU proceeds to S220 and controls the main motor 30 and the auxiliary motor 90 in the first drive mode. More specifically, the CPU controls the main motor 30, the engine 10, and the auxiliary motor 90 so that X% of the required drive torque Tqreq is distributed to the main drive shaft 60 and (100-X)% of the required drive torque Tqreq is distributed to the auxiliary drive shaft 80. In this example, X% is 50%. The CPU then proceeds from S220 to S295 and temporarily ends this routine.

[0020] On the other hand, if a warm-up request for the catalyst 11 has been issued, the CPU proceeds from S205 to S225, where it determines whether slip control of the starting clutch 40 (i.e., control to maintain the starting clutch 40 in a semi-engaged state) is feasible. More specifically, the CPU estimates the input shaft rotation speed NATin of the mechanical transmission 50, assuming that the gear of the mechanical transmission 50 is set to sixth gear, which is the highest gear, based on the rotation speed NMA of the main drive shaft 60 (vehicle speed SPD) and the gear ratio of sixth gear. The CPU then determines whether the estimated input shaft rotation speed NATin of the mechanical transmission 50 is equal to or less than a value D obtained by subtracting a predetermined clutch rotation speed difference α from a predetermined engine rotation speed NE0. If the estimated input shaft rotation speed NATin is equal to or less than the value D, it determines that slip control of the starting clutch 40 is feasible. If slip control is not feasible, the CPU proceeds from S225 to S210 described above.

[0021] On the other hand, if slip control is executable, the CPU proceeds from S225 to S230, engages the engine disengagement clutch 20, and maintains the rotational speed of the main motor 30 at a predetermined rotational speed N0, thereby operating the engine 10 to rotate at the predetermined rotational speed N0. This promotes warm-up of the catalyst 11. Next, the CPU proceeds from S230 to S235, and sets the starting clutch 40 to a slip state (half-engaged state).

[0022] Next, the CPU proceeds from S235 to S240 and executes catalyst warm-up shift control. More specifically, when the input shaft rotation speed NATin of the mechanical transmission 50 increases as the vehicle speed SPD increases and coincides with "a value D obtained by subtracting a predetermined clutch rotation speed difference α from the predetermined rotation speed NE0," the CPU changes the gear position of the mechanical transmission 50 from the current gear position to a gear position that is one step higher. That is, the CPU controls the gear position (i.e., the gear ratio) of the mechanical transmission 50 so that the input shaft rotation speed NATin of the mechanical transmission is lower than the input shaft rotation speed of the starting clutch 40 (the rotation speed of the main motor 30, which is set to the predetermined rotation speed NE0) by at least the clutch rotation speed difference α.

[0023] Next, the CPU proceeds from S240 to S245 to determine whether the wheels (81R, 81L) of the auxiliary drive shaft 80 are slipping. More specifically, the CPU determines that the wheels (81R, 81L) of the auxiliary drive shaft 80 are slipping when the rotational speed NSA of the auxiliary drive shaft 80 detected by the rotational speed sensor 106 is higher than the rotational speed NMA of the main drive shaft 60 detected by the vehicle speed sensor 103 by a predetermined value or more, and determines that the wheels (81R, 81L) of the auxiliary drive shaft 80 are not slipping otherwise. If the wheels (81R, 81L) of the auxiliary drive shaft 80 are slipping, the CPU proceeds from S245 to S215. Note that S245 may be omitted.

[0024] On the other hand, if the wheels (81R, 81L) of the auxiliary drive shaft 80 are not slipping, the CPU proceeds from S245 to S250 and controls the main motor 30 and the auxiliary motor 90 in the second drive mode. More specifically, the CPU controls the main motor 30, the engine 10, and the auxiliary motor 90 so that Y% of the required drive torque Tqreq is distributed to the main drive shaft 60 and (100-Y)% of the required drive torque Tqreq is distributed to the auxiliary drive shaft 80. The value Y is smaller than the value X. In this example, Y% is 20%. Thus, in the second drive mode, which is performed while catalyst warm-up control is being executed, the main motor 30 and the auxiliary motor 90 are controlled so that the ratio of the "drive torque distributed to the auxiliary drive shaft 80" to the "drive torque distributed to the main drive shaft 60" is larger than in the first drive mode, which is performed when catalyst warm-up control is not being executed, and drive power is preferentially distributed to the auxiliary drive shaft 80. The CPU then proceeds from S250 to S295.

[0025] (Example of operation) 3A shows the temporal changes in various parameters when no warm-up request for the catalyst 11 has been issued. In this example, the vehicle is stopped before time t1. Therefore, the input shaft rotation speed NATin of the mechanical transmission 50, depicted by the dashed line, is maintained at "0." Meanwhile, the engine rotation speed NE, depicted by the solid line, is maintained at a predetermined rotation speed N0. The gear position is first gear, and the starting clutch 40 is maintained in a slip state.

[0026] When the accelerator pedal is depressed at time t1, the motor torque of the main motor 30 increases, and therefore the clutch transmission torque also increases. As a result, the input shaft rotation speed NATin of the mechanical transmission 50 and the vehicle speed SPD gradually increase. Thereafter, at time t2, when the input shaft rotation speed NATin of the mechanical transmission 50 and the engine rotation speed NE match, the start clutch 40 changes from a slip state to an engaged state. As a result, from time t2 onwards, the input shaft rotation speed NATin and the engine rotation speed NE increase and decrease while remaining matched. In this example, since the vehicle speed continues to increase from time t1 onwards, the illustrated gear shifts are performed at times t3, t4, and t5 by normal gear shift control using the above-mentioned gear shift diagram.

[0027] 3(B) shows the temporal changes in various parameters when a warm-up request for the catalyst 11 is issued. In this example, the vehicle is stopped before time t1. Therefore, the input shaft rotation speed NATin of the mechanical transmission 50, depicted by the dashed line, is maintained at "0." Meanwhile, the engine rotation speed NE, depicted by the solid line, is maintained at a predetermined rotation speed N0. The gear position is first gear, and the starting clutch 40 is maintained in a slip state.

[0028] When the accelerator pedal is depressed at time t1, the motor torque of the main motor 30 increases, which in turn increases the clutch transmission torque. As a result, the input shaft rotation speed NATin of the mechanical transmission 50 and the vehicle speed SPD gradually increase. Thereafter, at time t2, when the input shaft rotation speed NATin reaches a value D obtained by subtracting a predetermined clutch rotation speed difference α from the engine rotation speed NE0, the catalyst warm-up shift control shifts the gear position of the mechanical transmission 50 from first to second. As a result, the input shaft rotation speed NATin of the mechanical transmission 50 decreases sharply and then begins to increase. Thereafter, the catalyst warm-up shift control similarly shifts the gears as shown at times t3, t4, t5, and t6, which are the limits for maintaining the slip state.

[0029] Because the mechanical transmission 50 does not have a sixth or higher gear, at time t7, the input shaft rotation speed NATin of the mechanical transmission 50 increases to the engine rotation speed NE. Therefore, at time t7, the start clutch 40 is shifted from a slip state to an engaged state. As a result, from time t7 onwards, the input shaft rotation speed NATin and the engine rotation speed NE increase while remaining the same. In this way, the period up to time t7 is a period during which catalyst warm-up control can be executed, and during this period the vehicle HV is run in the second drive mode.

[0030] As explained above, during catalyst warm-up control, the auxiliary motor 90 generates a large motor torque relative to the main motor 30. Therefore, even if the motor torque generated by the main motor 30 is not increased, a drive torque that satisfies the drive torque required by the user can be generated. In addition, the clutch transmission torque can be made relatively small, thereby reducing clutch loss. [Explanation of symbols]

[0031] 10...internal combustion engine, 30...main motor, 40...starting clutch, 50...mechanical transmission, 60...main drive shaft, 80...auxiliary drive shaft, 90...auxiliary motor.

Claims

[Claim 1] A vehicle control device applied to a hybrid vehicle including an internal combustion engine having a catalyst in an exhaust passage, a main motor having a rotary shaft connected to the internal combustion engine so as to be able to transmit power, a mechanical transmission connected to a main drive shaft having wheels attached to both ends so as to be able to transmit power, a clutch having an input shaft connected to the rotary shaft of the main motor and an output shaft connected to the input shaft of the mechanical transmission, and an auxiliary motor connected to an auxiliary drive shaft having wheels attached to both ends so as to be able to transmit power, When a warm-up request for the catalyst is generated, driving the main motor and operating the internal combustion engine so that the rotation speed of the internal combustion engine becomes a constant predetermined rotation speed; controlling a speed ratio achieved by the mechanical transmission so that the rotational speed of the input shaft of the mechanical transmission is lower than the rotational speed of the input shaft of the clutch; maintaining the clutch in a slip state when the rotational speed of the input shaft of the mechanical transmission is lower than the rotational speed of the input shaft of the clutch; Catalyst warm-up control is performed, During execution of the catalyst warm-up control, the main motor and the auxiliary motor are controlled so that the ratio of the drive shaft torque distributed to the auxiliary drive shaft to the drive torque distributed to the main drive shaft is increased compared to during non-execution of the catalyst warm-up control. Vehicle control device.

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