JP2024061026A - Vehicle control device - Google Patents

Abstract

[Problem] To provide a vehicle control device capable of reducing vibrations caused by engine torque fluctuations while driving at low vehicle speeds. [Solution] A slip control is executed to engage the disconnecting clutch K0 and put the starting clutch WSC into a slip state, and when a predetermined vibration generation condition is met during execution of driving control in which the vehicle is driven by the power of the engine 12, slip control is executed to put the disconnecting clutch K0 into a slip state, thereby reducing the transmission of torque fluctuations of the engine 12, which cause vibrations, to the automatic transmission 20. As a result, creep vibrations originating from torque fluctuations of the engine 12 can be reduced. [Selected Figure] Figure 1

Description

The present invention relates to a control device for a vehicle that uses at least an engine as a power source.

Patent document 1 describes a control device for a vehicle that includes an engine and an electric motor that function as a power source, a first clutch interposed between the engine and the power source, and a second clutch interposed in a power transmission path between the electric motor and the drive wheels. Specifically, Patent document 1 describes that when the vehicle starts, the drive torque of the power source is controlled to a target drive torque for starting, and the second clutch is made to slip. It also describes that when the temperature of the second clutch reaches or exceeds a predetermined temperature while the second clutch is slipping, the automatic transmission interposed between the power source and the drive wheels is shifted, thereby suppressing the temperature rise of the second clutch.

JP 2010-149629 A

In the vehicle described in Patent Document 1, when the vehicle is creeping at a low speed while the engine is running, the engine is operated at an idle speed to slip the second clutch. At this time, depending on the gear of the automatic transmission and the temperature of the hydraulic oil, there is a risk that the torque fluctuation of the engine transmitted via the second clutch will become large on the drive shaft.

The present invention was made against the background of the above circumstances, and its purpose is to provide a vehicle control device that can reduce vibrations caused by engine torque fluctuations that occur when traveling at low vehicle speeds.

The gist of the present invention is a control device for a vehicle including: (a) an engine that functions as a power source; a transmission that is interposed in a power transmission path between the engine and drive wheels; a first clutch that is provided in the power transmission path between the engine and the transmission; and a second clutch that is provided in the power transmission path between the first clutch and the transmission or within the transmission; (b) a control unit that, under a predetermined condition with the engine driven, engages the first clutch and executes slip control to put the second clutch into a slip state, and executes driving control to drive the vehicle using the engine power; and (c) the control unit executes slip control to put the first clutch into a slip state when a vibration generation condition that is specified in advance is met during the execution of the driving control.

According to the present invention, slip control is executed to engage the first clutch and put the second clutch into a slip state, and when a predetermined vibration generation condition is met during execution of driving control to drive the vehicle by engine power, slip control is executed to put the first clutch into a slip state, thereby reducing the transmission of engine torque fluctuations, which cause vibrations, to the transmission side. As a result, vehicle vibrations originating from engine torque fluctuations can be reduced.

1 is a diagram for explaining a schematic configuration of a hybrid vehicle to which the present invention is applied, and is also a diagram for explaining main parts of control functions and a control system for various controls in the vehicle. 4 is a flowchart illustrating a main part of the control operation of the electronic control device.

The following describes in detail the embodiments of the present invention with reference to the drawings. Note that in the following embodiments, the drawings have been simplified or modified as appropriate, and the dimensional ratios and shapes of the various parts are not necessarily drawn accurately.

Figure 1 is a diagram illustrating the general configuration of a hybrid vehicle 10 (hereinafter, vehicle 10) to which the present invention is applied, as well as a diagram illustrating the main parts of the control functions and control system for various controls in the vehicle 10. In Figure 1, the vehicle 10 is a hybrid vehicle equipped with an engine 12 and an electric motor MG that function as a power source. The vehicle 10 also has drive wheels 14 and a power transmission device 16 provided in the power transmission path between the engine 12 and the drive wheels 14.

The engine 12 is a known internal combustion engine. The engine torque Te of the engine 12 is controlled by an engine control device 50 provided in the vehicle 10, which is controlled by an electronic control device 90 described below.

The electric motor MG is connected to a battery 54 via an inverter 52 provided in the vehicle 10. The inverter 52 is controlled by an electronic control device 90, thereby controlling the MG torque Tm, which is the torque of the electric motor MG.

The power transmission device 16 includes a case 18, which is a non-rotating member, and includes a switch clutch K0, a starting clutch WSC, an automatic transmission 20, a reduction gear mechanism 22, a differential gear 24, and the like. The switch clutch K0 is provided between the engine 12 and the electric motor MG and the automatic transmission 20 in the power transmission path between the engine 12 and the drive wheels 14. The starting clutch WSC is provided between the switch clutch K0 and the automatic transmission 20 in the power transmission path between the engine 12 and the drive wheels 14. The reduction gear mechanism 22 is connected to a transmission output gear 26, which is an output rotating member of the automatic transmission 20. The switch clutch K0 corresponds to the first clutch of the present invention, and the starting clutch WSC corresponds to the second clutch of the present invention.

The power transmission device 16 also includes a pair of drive shafts 28 connected to the differential gear 24. The power transmission device 16 also includes, within the case 18, an engine connecting shaft 30 that connects the engine 12 to the on-off clutch K0, and an electric motor connecting shaft 32 that connects the on-off clutch K0 to the starting clutch WSC.

The electric motor MG is connected to the electric motor connecting shaft 32 inside the case 18. In other words, the electric motor MG is connected to the power transmission path between the engine 12 and the drive wheels 14 so as to be capable of transmitting power.

The on-off clutch K0 is, for example, a known friction engagement device. The on-off clutch K0 has its torque capacity, K0 torque capacity Tk0, changed by the regulated K0 oil pressure PRk0 supplied from the hydraulic control circuit 56 provided in the vehicle 10, thereby switching between operating states, i.e., control states, such as an engaged state (fully engaged state), a slip state, and a released state.

The starting clutch WSC is a wet friction engagement device, for example, composed of a multi-plate clutch pressed by a hydraulic actuator. The control state of the starting clutch WSC is switched by changing the WSC torque capacity Twsc, which is the torque capacity of the starting clutch WSC, using the regulated WSC oil pressure PRwsc supplied from the hydraulic control circuit 56.

The automatic transmission 20 is interposed in the power transmission path between the engine 12 and the drive wheels 14. The automatic transmission 20 is, for example, a known planetary gear type automatic transmission equipped with a planetary gear device and an engagement device CB. The engagement device CB includes, for example, a plurality of known friction engagement devices. The control state of each of the engagement devices CB is switched by changing the CB torque capacity Tcb, which is the torque capacity of each of the engagement devices CB, using the regulated CB hydraulic pressure PRcb supplied from the hydraulic control circuit 56.

The vehicle 10 is equipped with an electronic control device 90 for executing various controls of the vehicle 10. The electronic control device 90 is supplied with various detection signals, etc., from various sensors 70, 72, 74, 76, 78, 80, 82, 84, 86, etc. equipped in the vehicle 10 (for example, engine speed Ne, which is the rotation speed of the engine 12; MG speed Nm, which is the rotation speed of the electric motor MG; input speed Ni, which is the rotation speed of the transmission input shaft 38 of the automatic transmission 20; output speed No, which is the rotation speed of the transmission output gear 26 corresponding to the vehicle speed V; accelerator opening θacc; throttle valve opening θth; brake signal Bon; battery temperature THbat; battery charge/discharge current Ibat; battery voltage Vbat; hydraulic oil temperature THoil, which is the temperature of the hydraulic oil supplied to the hydraulic control circuit 56, etc.).

The electronic control device 90 outputs various command signals (e.g., engine control command signal Se, MG control command signal Sm, CB hydraulic control command signal Scb, K0 hydraulic control command signal Sk0, WSC hydraulic control command signal Swsc, etc.) to each of the devices 50, 52, 56, etc. provided in the vehicle 10.

The electronic control device 90 includes a power source control means, i.e., a power source control unit 92, a clutch control means, i.e., a clutch control unit 94, and a creep control means, i.e., a creep control unit 96, in order to realize various controls in the vehicle 10.

The power source control unit 92 includes a function for controlling the operation of the engine 12 and a function for controlling the operation of the electric motor MG, and executes hybrid drive control using the engine 12 and the electric motor MG, etc., using these control functions.

The power source control unit 92 calculates the amount of drive required by the driver for the vehicle 10, for example, by applying the accelerator opening θacc and the vehicle speed V to a drive demand map. The drive demand map is a relationship for calculating the drive demand that is experimentally or design-wise determined and stored in advance, i.e., is predetermined. The drive demand is, for example, the required drive torque Trdem [Nm] or the required drive force Frdem [N] at the drive wheels 14. In other words, the required drive torque Trdem is the required drive power Prdem [W] at the vehicle speed V at that time. The power source control unit 92 outputs an engine control command signal Se for controlling the engine 12 and an MG control command signal Sm for controlling the electric motor MG so as to realize the required drive power Prdem, taking into account the transmission loss, the auxiliary load, the gear stage Gear of the automatic transmission 20, etc.

When the required driving power P rdem can be met only by the output of the electric motor MG, the power source control unit 92 sets the driving mode for driving the vehicle 10 to the BEV driving mode. The BEV driving mode is a motor driving mode that allows motor driving (=BEV driving) in which the vehicle runs using only the electric motor MG as a power source when the on-off clutch K0 is in a released state. On the other hand, when the required driving power P rdem cannot be met without using at least the output of the engine 12, the power source control unit 92 sets the driving mode to the engine driving mode, i.e., the HEV driving mode. The HEV driving mode is a hybrid driving mode that allows engine driving (=HEV driving) in which the vehicle runs using at least the engine 12 as a power source when the on-off clutch K0 is in an engaged state. On the other hand, even if the required driving power P rdem can be met only by the power of the electric motor MG, the power source control unit 92 establishes the HEV driving mode when the battery 54 needs to be charged or when the engine 12 needs to be warmed up.

For example, when traveling in BEV drive mode, the clutch control unit 94 engages the starting clutch WSC while disengaging the connecting/disconnecting clutch K0. This enables motor driving using the electric motor MG as a power source. At this time, the disconnecting clutch K0 is disengaged, preventing losses due to dragging of the engine 12. Furthermore, when traveling in HEV drive mode, the clutch control unit 94 engages the starting clutch WSC and the connecting/disconnecting clutch K0. This enables hybrid driving using the engine 12 and the electric motor MG as a power source.

When the shift range is switched to D range, which is a forward driving range, or R range, which is a reverse driving range, and the driver releases the brake pedal from a state in which the brake pedal is depressed, the creep control unit 96 executes creep control to cause the vehicle 10 to creep at a low vehicle speed. The creep control unit 96 corresponds to the control unit of the present invention. Also, the state in which the shift range is in D range or R range and the brake pedal is released corresponds to the specified state of the present invention.

When the engine 12 is driven to perform creep running, the creep control unit 96 executes creep control to run the vehicle 10 by the power of the engine 12. At this time, the creep control unit 96 outputs a command to the power source control unit 92 to control the engine 12 to a predetermined idle rotation speed Neidle. The creep control unit 96 also outputs a command to the clutch control unit 94 to engage (fully engage) the disconnecting clutch K0 so that the power of the engine 12 is transmitted to the drive wheels 14, and to execute slip control to put the starting clutch WSC in a slip state. In response to this, the clutch control unit 94 controls the WSC torque capacity Twsc of the starting clutch WSC so that the power required for creep running is transmitted to the automatic transmission 20. The creep control described above causes the vehicle 10 to creep run by the power of the engine 12. The creep control described above corresponds to the running control of the present invention.

It is known that engine vibration occurs due to torque fluctuations in the engine 12 at low vehicle speeds of about 5 to 10 km/h. When this engine vibration is transmitted to the drive wheels 14 via the on-off clutch K0 and the starting clutch WSC, depending on the driving conditions of the vehicle 10, the vibration (hereinafter referred to as creep vibration) generated in the power transmission path such as the drive shaft 28 may become large, causing discomfort to vehicle occupants. In response to this, the creep control unit 96 executes slip control to put the on-off clutch K0 into a slip state when conditions for large creep vibration (hereinafter referred to as vibration generation conditions) are met while creep control is being executed with the engine 12 running.

Here, the vibration generation conditions are determined and specified in advance through experiments or design. Creep vibration becomes large in a region where the resonance point of the engine vibration and the resonance point of the vehicle 10 coincide or are close to each other. In addition, the resonance point of the vehicle 10 varies depending on, for example, the vehicle speed V, the hydraulic oil temperature THoil, and the gear stage Gear of the automatic transmission 20. Therefore, the vibration generation conditions are stored as a relationship map of vibration generation conditions, with, for example, the vehicle speed V, the hydraulic oil temperature THoil, and the gear stage Gear of the automatic transmission 20 as parameters. In addition to these parameters, the accelerator opening θacc, the engine rotation speed Ne, etc. may also be applied as the relationship map of vibration generation conditions.

The creep control unit 96 determines whether or not a vibration generation condition is met during creep control with the engine 12 running. The creep control unit 96 applies the vehicle speed V, hydraulic oil temperature THoil, and gear position of the automatic transmission 20, which are detected at any time, to a relationship map of vibration generation conditions, and determines that the vibration generation condition is met if the current driving state meets the vibration generation condition defined in the relationship map.

When the creep control unit 96 determines that the vibration generation condition is satisfied during creep driving, it switches the disconnecting clutch K0 to a slip state. For example, the slip amount Nslip or the K0 torque capacity Tk0 of the disconnecting clutch K0, at which the creep vibration generated during the vibration generation condition is within an acceptable range, is determined in advance experimentally or by design and stored in a map or the like. When the creep control unit 96 determines that the vibration generation condition is satisfied during creep driving, it outputs a command to the clutch control unit 94 to control the disconnecting clutch K0 so that the slip amount Nslip or the K0 torque capacity Tk0 of the disconnecting clutch K0 is obtained from the map. In response to this, the clutch control unit 94 executes slip control of the disconnecting clutch K0, thereby reducing the creep vibration generated due to the torque fluctuation of the engine 12.

When the creep control unit 96 determines that the driving condition of the vehicle 10 is no longer within the vibration generation condition, i.e., that the vehicle has passed through the region in which the vibration generation condition is satisfied, the creep control unit 96 releases the slip control of the disconnecting clutch K0 and returns the disconnecting clutch K0 to a fully engaged state. Whether or not the region in which the vibration generation condition is satisfied is determined based on, for example, the vehicle speed V. When the creep control unit 96 determines that, for example, the vehicle speed V has passed through a vehicle speed range (e.g., 5 to 10 km/h) that corresponds to a predefined region in which the vibration generation condition is satisfied, the creep control unit 96 returns the disconnecting clutch K0 to a fully engaged state. As a result, normal creep driving is restored.

Figure 2 is a flowchart explaining the main control operations of the electronic control unit 90, and is a flowchart explaining the control operations for reducing creep vibrations that occur during creep driving with the engine 12 in a driving state. This flowchart is executed repeatedly during creep driving with the engine 12 in a driving state.

First, in step S10 (hereinafter, steps are omitted) corresponding to the control function of the creep control unit 96, the engine rotation speed Ne is controlled to the idle rotation speed Neidle. Also, the disconnecting clutch K0 is engaged (fully engaged), and slip control of the starting clutch WSC is executed. Next, in S20 corresponding to the control function of the creep control unit 96, it is determined whether or not a vibration generation condition that increases creep vibration is established. If the determination in S20 is negative, this routine is terminated. If the determination in S20 is positive, in S30 corresponding to the control function of the creep control unit 96, slip control of the disconnecting clutch K0 is executed. In S40 corresponding to the control function of the creep control unit 96, it is determined whether or not the vehicle has passed through a vehicle speed range in which the vibration generation condition is established. If the determination in S40 is negative, the process returns to S30 and the slip control of the disconnecting clutch K0 is continued. If the determination in S40 is positive, in S50 corresponding to the control function of the creep control unit 96, the disconnecting clutch K0 is returned to a fully engaged state.

As described above, according to this embodiment, slip control is executed to engage the disconnecting clutch K0 and put the starting clutch WSC into a slip state, and if a predetermined vibration generation condition is met during execution of creep control to run the vehicle using the power of the engine 12, slip control is executed to put the disconnecting clutch K0 into a slip state, thereby reducing the transmission of torque fluctuations of the engine 12, which cause vibrations, to the automatic transmission 20. As a result, creep vibrations originating from torque fluctuations of the engine 12 can be reduced.

The above describes in detail an embodiment of the present invention based on the drawings, but the present invention can also be applied in other aspects.

For example, in the above embodiment, the starting clutch WSC is provided between the on-off clutch K0 and the automatic transmission 20, and causes the on-off clutch K0 to slip during creeping, but the present invention is not necessarily limited to this. For example, during creeping, the starting clutch WSC may be provided in the automatic transmission 20 and controls the slip of an input clutch that is engaged during creeping. In this case, the input clutch corresponds to the second clutch of the present invention.

Note that the above is merely one embodiment, and the present invention can be implemented in various forms with various modifications and improvements based on the knowledge of those skilled in the art.

10: Hybrid vehicle 12: Engine 14: Drive wheels 20: Automatic transmission (transmission) 90: Electronic control device (control device) 96: Creep control unit (control unit) K0: On-off clutch (first clutch) WSC: Starting clutch (second clutch)

Claims (1)

A control device for a vehicle including an engine that functions as a power source, a transmission that is interposed in a power transmission path between the engine and a drive wheel, a first clutch that is provided between the engine and the transmission in the power transmission path, and a second clutch that is provided between the first clutch and the transmission in the power transmission path or within the transmission,
a control unit that executes slip control to engage the first clutch and place the second clutch in a slip state under a predetermined condition while the engine is running, and executes running control to run the vehicle by power of the engine,
The control device for a vehicle, wherein the control unit executes slip control to put the first clutch into a slip state when a predetermined vibration generation condition is satisfied during execution of the driving control.

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