Controller of starting clutch for vehicle

Abstract

To provide a controller of a starting clutch for a vehicle that is not likely to be damaged even when limp-home driving requiring differential of the starting clutch is performed in a high-speed gear stage of a stepped automatic transmission.SOLUTION: In a state where a low-speed gear stage of an automatic transmission 38 fails and use of the low-speed gear stage is limited, when differential (slip) of a starting clutch 36 is required, a starting clutch protection control unit 100 limits an input rotation speed to a starting clutch 36 or a driving force input to the starting clutch 36 so that a cumulative value ΣQcl (estimated value) of a heat generation amount Qcl of the starting clutch 36 falls within a predetermined value (allowable value) Q1. This makes it possible to limit increase in load on the starting clutch 36, so that an amount of heat generated is less likely to exceed an allowable heat amount, and thermal protection of the starting clutch 36 is performed.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a control device for a starting clutch for a vehicle, and particularly to a technique for performing thermal protection of the starting clutch.

Background Art

[0002] A vehicle equipped with a starting clutch that disconnects and connects between a drive source and a stepped automatic transmission is known. For example, a hybrid vehicle including an engine, an electric motor, a first clutch that disconnects and connects between the engine and the electric motor, and a second clutch (starting clutch) that disconnects and connects between the electric motor and a stepped automatic transmission, wherein the engine and the electric motor are used as power sources for traveling, is one such example. The vehicle described in Patent Document 1 is an example thereof.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, when a low - speed gear stage on the low - speed side where the gear ratio of the stepped automatic transmission is relatively large fails, limp - home driving is performed in the high - speed gear stage of the stepped automatic transmission. However, at the start of such limp - home driving (retreat driving), since the input torque of the stepped automatic transmission is increased and the load on the starting clutch becomes large, the amount of heat generated by the starting clutch easily exceeds the allowable amount of heat, and there is room for improvement from the viewpoint of thermal protection of the starting clutch.

[0005] The present invention has been made against the background of the above circumstances, and an object thereof is to provide a control device for a starting clutch for a vehicle in which the starting clutch is sufficiently thermally protected even when limp - home driving that requires differential of the starting clutch is performed in the high - speed gear stage of a stepped automatic transmission.

Means for Solving the Problem

[0006] The gist of the present invention is a control device for a vehicle starting clutch used in a vehicle equipped with (a) a starting clutch that is interposed between a drive source and a stepped transmission, and (b) a starting clutch protection control unit that restricts the input rotational speed and / or driving force input to the starting clutch in a case where differential of the starting clutch is required during running in a state where use of a low-speed gear stage of the stepped automatic transmission is restricted.

Effect of the Invention

[0007] According to such a control device for a vehicle starting clutch, in a case where differential of the starting clutch is required during running in a state where use is restricted due to an abnormality in a low-speed gear stage of the stepped automatic transmission, the input rotational speed and / or driving force input to the starting clutch is restricted by the starting clutch protection control unit. Thereby, an increase in the load on the starting clutch is restricted, so that it becomes difficult for the generated heat amount to exceed the allowable heat amount, and thermal protection of the starting clutch is performed.

[0008] Here, preferably, when an abnormality occurs in a low-speed gear stage of the stepped automatic transmission and use is restricted, the shift stage of the stepped automatic transmission is switched to a shift stage on the higher-speed side than the low-speed stage where the abnormality has occurred, and a retreat running control unit that differentially operates the starting clutch to run the vehicle is provided. Thereby, limp-home running becomes easy.

[0009] Also, preferably, the starting clutch protection control unit gives priority to restricting the input rotational speed input to the starting clutch among the restriction of the input rotational speed input to the starting clutch and the restriction of the driving force input to the starting clutch. Since the restriction of the input rotational speed input to the starting clutch is preferentially implemented, it becomes easy to suppress the heat generation amount in the starting clutch.

[0010] Further preferably, when it is estimated that the amount of heat generated in the starting clutch will be equal to or greater than a predetermined value after restricting the input rotational speed input to the starting clutch, the starting clutch protection control unit restricts the driving force input to the starting clutch and / or restricts the transmission torque capacity of the starting clutch so that the amount of heat generated in the starting clutch becomes an allowable amount. Thereby, since the amount of heat generated in the starting clutch is restricted, it is possible to avoid the starting clutch from entering a overheated state.

Brief Description of Drawings

[0011]

Figure 1

Figure 2

Embodiments for Carrying Out the Invention

[0012] The present invention is applied to an engine vehicle equipped with an engine as a drive source, an electric (BEV) vehicle equipped with an electric motor as a drive source, and a HEV vehicle equipped with an engine and an electric motor as drive sources. The HEV vehicle is, for example, a 1M hybrid type vehicle that can switch between a first driving mode that runs using at least the engine and a second driving mode that runs using the electric motor. As the electric motor, a motor generator having a function as a generator is preferably used, but an electric motor that does not function as a generator can also be used. A starting clutch and a stepped automatic transmission are provided in the power transmission path between the drive source and the drive wheels. In a 1M (motor) hybrid type vehicle, a first clutch that disconnects and connects between the engine and the electric motor and a second clutch that disconnects and connects between the electric motor and the stepped automatic transmission are provided, and the second clutch functions as a starting clutch. One of the plurality of shift oil pressure type friction engagement devices in the stepped automatic transmission can also be used as the second clutch.

Examples

[0013] Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings. In FIG. 1, a vehicle 10 includes an electronic control unit 90 as a control device according to an embodiment of the present invention. The vehicle 10 is a hybrid electric (HEV) vehicle including an engine 12 and a motor MG as drive sources. The vehicle 10 includes the engine 12, drive wheels 14 which are the left and right rear wheels or front wheels, and a power transmission device 18 provided in a power transmission path between the engine 12 and the drive wheels 14. The engine 12 is an internal combustion engine such as a gasoline engine or a diesel engine. The engine 12 has its engine torque Te, which is the torque of the engine 12, controlled by the electronic control unit 90 controlling engine control equipment 22 including a throttle actuator, a fuel injection device, an ignition device, etc. The motor MG is a rotating electric machine having a function as an engine that generates mechanical power from electric power and a function as a generator that generates electric power from mechanical power, and is a so-called motor generator. The motor MG is connected to a battery 28 via a PCU (Power Control Unit) 24 having an inverter or the like. The motor MG has its MG torque Tmg, which is the torque of the motor MG, controlled by the electronic control unit 90 controlling the PCU 24.

[0014] The power transmission device 18 includes a K0 clutch 34, a launch clutch 36, an automatic transmission (AT) 38, etc. within a case 32 which is a non-rotating member attached to the vehicle body, and power is transmitted from a transmission output shaft 40 to the drive wheels 14 via a differential gear 42 and a pair of drive shafts 44. The K0 clutch 34 is a first clutch that stages the connection between the engine 12 and the motor MG. The launch (WSC) clutch 36 is a second engagement device that stages the connection and disconnection between the motor MG and the drive wheels 14, and is a wet multi-plate launch clutch (second clutch) that is semi-engaged at vehicle start by being slip-engagedly controlled by the electronic control unit 90.

[0015] The power transmission device 18 includes, within the case 32, an engine connecting shaft 46 that connects the engine 12 and the K0 clutch 34, and a motor connecting shaft 48 that connects the K0 clutch 34 and the start clutch 36. The motor MG is connected to the motor connecting shaft 48 in a power-transmittable manner. Both the K0 clutch 34 and the start clutch 36 have their control states, such as the engaged state and the released state, switched according to commands from the electronic control device 90. The K0 clutch 34 has its control state switched by changing the K0 torque Tk0, which is the torque capacity of the K0 clutch 34, by means of the K0 hydraulic pressure PRk0 supplied from the hydraulic control circuit 52. The start clutch 36 has its control state switched by changing the WSC torque Twsc, which is the torque capacity of the start clutch 36, by means of the WSC hydraulic pressure PRwsc supplied from the hydraulic control circuit 52. The input-side member of the start clutch 36 is connected to the motor connecting shaft 48, and the output-side member of the start clutch 36 is connected to the transmission input shaft 50, which is the input rotating member of the automatic transmission 38.

[0016] The automatic transmission 38 is, for example, a planetary gear type automatic transmission including a plurality of planetary gear devices and a plurality of hydraulic friction engagement devices CB. Each of the plurality of hydraulic friction engagement devices CB has its control state, such as the engaged state and the released state, switched by changing its respective torque capacity, the CB torque Tcb, by means of the regulated CB hydraulic pressure PRcb supplied from the hydraulic control circuit 52. The automatic transmission 38 is a stepped automatic transmission in which any one of the engagement devices CB is selectively engaged to form any one of a plurality of gear stages having different gear ratios γat (= input rotational speed Ni / output rotational speed No).

[0017] Vehicle 10 is equipped with a mechanical oil pump 58 and an electric oil pump 60. The mechanical oil pump 58 is connected to, for example, the motor coupling shaft 48 in a power-transmittable manner via a gear, a belt, a chain, or the like, and is driven by at least one of the engine 12 and the motor MG to discharge hydraulic oil. The electric oil pump 60 is rotationally driven by a pump motor (not shown) to discharge hydraulic oil. The hydraulic oil discharged by the mechanical oil pump 58 and the electric oil pump 60 is supplied to the hydraulic control circuit 52. The hydraulic control circuit 52 outputs, based on the hydraulic oil discharged by the mechanical oil pump 58 and the electric oil pump 60, regulated CB hydraulic pressure PRcb, K0 hydraulic pressure PRk0, WSC hydraulic pressure PRwsc, etc., respectively.

[0018] Vehicle 10 is equipped with an electronic control unit 90 as a control device that executes various controls. The electronic control unit 90 includes a so-called microcomputer and executes various controls of the vehicle 10. The electronic control unit 90 is configured to include a plurality of computers such as an engine control computer, an MG control computer, and a hydraulic control computer as necessary.

[0019] The electronic control unit 90 is supplied with signals related to various information necessary for various controls, such as the engine speed Ne which is the rotational speed of the engine 12, the input rotational speed Ni, the output rotational speed No corresponding to the vehicle speed V, the MG rotational speed Nmg which is the rotational speed of the electric motor MG, the accelerator opening θacc which represents the driver's output demand amount by the operation amount of the accelerator pedal etc., the throttle valve opening θth which is the opening of the electronic throttle valve, the brake ON signal Bon which is a signal indicating that the brake pedal for operating the wheel brake is being operated by the driver, the battery temperature THbat, the battery charge / discharge current Ibat, the battery voltage Vbat of the battery 28 which is a power storage device, and the oil temperature THoil which is the temperature of the working oil in the hydraulic control circuit 52, from, for example, an engine speed sensor 70, an input rotational speed sensor 72, an output rotational speed sensor 74, an MG rotational speed sensor 76, an accelerator opening sensor 80, a throttle valve opening sensor 82, a brake switch 84, a battery sensor 86, an oil temperature sensor 88, etc. The MG rotational speed Nmg is the same as the rotational speed of the input side member of the starting clutch 36, and the input rotational speed Ni is the same as the rotational speed of the output side member of the starting clutch 36. From these rotational speeds Nmg and Ni, the operating state of the starting clutch 36, that is, whether it is in a fully engaged state, a slip engaged state, or an open state, can be determined.

[0020] From the electronic control unit 90, engine control command signals Se for controlling the engine 12, MG control command signals Smg for controlling the electric motor MG, CB hydraulic control command signals Scb for controlling the engagement device CB, K0 hydraulic control command signals Sk0 for controlling the K0 clutch 34, WSC hydraulic control command signals Swsc for controlling the starting clutch 36, electric oil pump control command signals Seop, etc. are output to each device provided in the vehicle 10, such as the engine control device 22, the PCU 24, the hydraulic control circuit 52, the electric oil pump 60, etc. In addition to the linear solenoid valve SLW controlled by the WSC hydraulic control command signal Swsc, the hydraulic control circuit 52 is provided with various solenoid valves for switching the oil passage and controlling the oil pressure according to the K0 hydraulic control command signal Sk0 and the CB hydraulic control command signal Scb.

[0021] The electronic control device 90 functionally includes a power source control unit 92, a start clutch engagement control unit 94, a shift control unit 96, an evacuation travel control unit 98, and a start clutch protection control unit 100 corresponding to the main parts of various controls in the vehicle 10.

[0022] The power source control unit 92 calculates the drive demand amount for the vehicle 10 by the driver, for example, by applying the accelerator opening θacc and the vehicle speed V to a drive demand amount map. The power source control unit 92 calculates the required input torque Tidemand at the transmission input shaft 50 that can achieve the required drive amount, considering transmission losses, accessory loads, the gear ratio γat of the automatic transmission 38, etc., and obtains the target engine torque Tetgt and the target MG torque Tmtgt at which the required input torque Tidemand can be obtained. Then, it outputs an engine control command signal Se to control the engine 12 so that the target engine torque Tetgt is output, and outputs an MG control command signal Smg to control the motor MG so that the target MG torque Tmtgt is output.

[0023] When the power source control unit 92 can satisfy the required input torque Tidem only with the output of the electric motor MG, for example, it is set to the BEV (Battery Electric Vehicle) driving mode, which is a motor driving mode in which the electric motor MG is driven only by the power from the battery 28 to run. In the BEV driving mode, the K0 clutch 34 is released to stop the engine 12, and the start clutch 36 is engaged to run only with the electric motor MG. In this BEV driving mode, the MG torque Tmg is controlled to realize the required input torque Tidem. On the other hand, when the power source control unit 92 cannot satisfy the required input torque Tidem without using at least the output of the engine 12, it is set to the HEV (Hybrid Electric Vehicle) driving mode, which is an engine driving mode. In the HEV driving mode, both the K0 clutch 34 and the start clutch 36 are engaged, and the engine runs using at least the engine 12 as a power source, that is, HEV driving is performed. In this HEV driving mode, the engine torque Te is controlled to realize all or part of the required input torque Tidem, and the MG torque Tmg is controlled to supplement the torque that is insufficient with the engine torque Te for the required input torque Tidem.

[0024] When the vehicle 10 is stopped, the start clutch engagement control unit 94 controls to maintain the start clutch 36 in an open state or a slip engagement state. When the start clutch 36 is set in the slip engagement state in the vehicle stop state, for example, when a brake-off operation is performed with the accelerator off, the vehicle 10 can be run in a so-called creep running in which the vehicle 10 moves slowly. Also, when the vehicle 10 is running in the BEV driving mode or the HEV driving mode, the start clutch 36 is controlled to be maintained in a fully engaged state.

[0025] The shift control unit 96 makes a shift determination for the automatic transmission 38 using, for example, a shift map that is a predefined relationship, and outputs a CB hydraulic pressure control command signal Scb for switching the gear stage of the automatic transmission 38 as necessary. The shift map is a predetermined relationship having shift lines for determining shifts of the automatic transmission 38 on a two-dimensional coordinate with, for example, vehicle speed V and required drive torque Trdem as variables.

[0026] When an abnormality (failure) occurs in the low-speed gear stage of the automatic transmission 38 and the use of the low-speed gear stage is restricted, the retreat travel control unit 98 switches the automatic transmission 38 from the low-speed gear stage (for example, the first-speed gear stage) to a high-speed gear stage on the higher-speed side (the side with a smaller gear ratio) (for example, a gear stage of second speed or higher), and if it is necessary to increase the rotational speed of the engine 12 or the electric motor MG, etc., performs differential (slip) of the launch clutch 36 to perform retreat travel (limp home travel).

[0027] When an abnormality occurs in a gear stage with a large gear ratio such as the first speed or the second speed in the low-speed gear stage of the automatic transmission 38 and the use of the low-speed gear stage is restricted, and differential (slip) of the launch clutch 36 is necessary, the launch clutch protection control unit 100 restricts the input rotational speed to the launch clutch 36 and / or the driving force input to the launch clutch 36, that is, the input rotational speed to the automatic transmission 38 or the driving force to the automatic transmission 38. Preferably, the launch clutch protection control unit 100 gives priority to restricting the input rotational speed to the launch clutch 36 among the restriction of the input rotational speed to the launch clutch 36 and the restriction of the driving force input to the launch clutch 36.

[0028] The starting clutch protection control unit 100 limits the input rotation speed to the starting clutch 36, and then, when it is estimated that the cumulative value ΣQcl (estimated value) of the heat generation amount Qcl generated in the starting clutch 36 from the differential start becomes equal to or greater than a preset predetermined value Q1, it limits the driving force input to the starting clutch 36 so that the heat generation amount generated in the starting clutch 36 becomes the preset allowable amount, or limits the torque transmission capacity of the starting clutch 36. The preset predetermined value Q1 is an allowable value at which heat protection due to overheating of the starting clutch 36 becomes difficult, and is a value set experimentally in advance.

[0029] The heat generation amount Qcl per unit time of the starting clutch 36 is estimated, for example, based on the following formula (1), where the differential rotation speed of the starting clutch 36 is ΔNcl (rpm), the transmitted torque (capacity) of the starting clutch 36 is Tcl (Nm), and the friction material area of the starting clutch 36 is Scl. Qcl = (ΔNcl × 2π / 60) × Tcl / Scl ···(1)

[0030] FIG. 2 is a flowchart for explaining the main part of the control operation of the electronic control unit 90. In FIG. 2, at step S1 (hereinafter, steps are omitted), it is determined whether or not the low-speed gear stage is unavailable due to a failure of the automatic transmission 38. If the determination at S1 is negative, this routine ends. However, if it is positive, at S2, it is determined whether differential (slip) is required for the launch clutch 36 for limp-home driving. If the determination at S2 is negative, this routine ends. However, if it is positive, at S3, it is determined whether or not the cumulative value ΣQcl of the heat generation amount Qcl generated by differential in the launch clutch 36 from the start of differential has become equal to or greater than a predetermined value Q1 set in advance. If the determination at S3 is negative, this routine ends. However, if it is positive, at S4, for example, by controlling the motor MG, the rotational speed of the motor connection shaft 48, that is, the input rotational speed of the launch clutch 36, is limited. Next, at S5, even after the input rotational speed of the launch clutch 36 is limited, it is determined whether or not the cumulative value ΣQcl (estimated value) of the heat generation amount Qcl of the launch clutch 36 is likely to become equal to or greater than the predetermined value Q1. If the determination at S5 is negative, this routine ends. However, if it is positive, at S6, the driving force input to the launch clutch 36 and / or the transmission torque (capacity) of the launch clutch 36 are limited so that the cumulative value ΣQcl (estimated value) of the heat generation amount Qcl of the launch clutch 36 falls within the predetermined value Q1.

[0031] As described above, according to the present embodiment, when differential (slip) of the launch clutch 36 is required in a state where the low-speed gear stage of the automatic transmission 38 has failed and the use of the low-speed gear stage is restricted by the launch clutch protection control unit 100, the input rotational speed of the launch clutch 36 and / or the driving force input to the launch clutch 36 are restricted so that the cumulative value ΣQcl (estimated value) of the heat generation amount Qcl of the launch clutch 36 falls within a predetermined value (allowable value) Q1. Thereby, an increase in the load on the launch clutch 36 is restricted, so that it becomes difficult for the generated heat amount to exceed the allowable heat amount, and thermal protection of the launch clutch 36 is performed.

[0032] Further, in this embodiment, when an abnormality occurs in the low-speed gear stage of the automatic transmission 38 and the use of the low-speed gear stage is restricted, the gear stage of the automatic transmission 38 is switched to a gear stage on the higher-speed side than the low-speed stage where the abnormality has occurred, and a retreat travel control unit 98 that differentially operates the starting clutch 36 to drive the vehicle 10 is provided. This facilitates limp-home travel.

[0033] Also, in this embodiment, the starting clutch protection control unit 100 gives priority to restricting the input rotation speed of the starting clutch 36 among restricting the input rotation speed of the starting clutch 36 and restricting the driving force input to the starting clutch 36. Since the restriction of the input rotation speed of the starting clutch 36 is preferentially implemented, it becomes easy to suppress the amount of heat generated within the starting clutch 36.

[0034] Preferably, after restricting the input rotation speed of the starting clutch 36, when it is estimated that the cumulative value ΣQcl (estimated value) of the heat generation amount Qcl generated in the starting clutch 36 becomes equal to or greater than a predetermined value (allowable value) Q1, the driving force input to the starting clutch 36 is restricted and / or the transmission torque capacity of the starting clutch 36 is restricted so that the cumulative value ΣQcl (estimated value) of the heat generation amount Qcl generated in the starting clutch 36 falls within the predetermined value (allowable value) Q1. Thereby, since the heat generation amount of the starting clutch 36 is restricted, it is avoided that the starting clutch 36 enters an overheated state.

[0035] As described above, the embodiments of the present invention have been described in detail based on the drawings, but this is merely one embodiment, and the present invention can be implemented in various modified and improved forms based on the knowledge of those skilled in the art.

Explanation of Reference Numerals

[0036] 10: Vehicle, 12: Engine (driving source), 14: Driving wheel, 36: Starting clutch, 38: Automatic transmission (step-type automatic transmission), 90: Electronic control device (control device), 94: Starting clutch engagement control unit, 98: Retreat travel control unit, 100: Starting clutch protection control unit, MG: Electric motor (driving source)

Claims

1. A control device for a vehicle starting clutch used in a vehicle comprising a starting clutch that step-connects between a drive source and a stepped transmission, wherein in the case of running where differential of the starting clutch is required in a state where use of a low gear stage of the stepped automatic transmission is restricted, a starting clutch protection control unit that restricts the input rotational speed and / or driving force to the starting clutch is provided. A control device for a vehicle starting clutch, characterized by the above.

2. When an abnormality occurs in a low gear stage of the stepped automatic transmission and use of the low gear stage is restricted, a shift stage of the stepped automatic transmission is switched to a shift stage on the higher speed side than the low speed stage where the abnormality has occurred, and a retreat running control unit that differentially operates the starting clutch to run the vehicle is further provided. The control device for a vehicle starting clutch according to Claim 1, characterized by the above.

3. The starting clutch protection control unit prioritizes restriction of the input rotational speed to the starting clutch among restriction of the input rotational speed to the starting clutch and restriction of the driving force to the starting clutch. The control device for a vehicle starting clutch according to Claim 1, characterized by the above.

4. After restricting the input rotational speed input to the starting clutch, when it is estimated that the amount of heat generated in the starting clutch becomes equal to or more than a predetermined value, the driving force input to the starting clutch is restricted so that the amount of heat generated in the starting clutch becomes an allowable amount or the capacity of the starting clutch is restricted. The control device for a vehicle starting clutch according to any one of Claims 1 to 3, characterized by the above.

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