JP7571703B2 - Vehicle control device - Google Patents

Description

The present invention relates to a vehicle control device, and in particular to backlash elimination control that eliminates backlash in the gear mechanism when the transmission is switched from one of the forward gear and reverse gear to the other.

When a shift operation that reverses the drive direction is performed, backlash in the gear mechanism can cause rattle shocks (such as teeth rattles and torque fluctuations), so a vehicle control device has been proposed that controls the output of the drive power source to eliminate rattle in the gear mechanism (see Patent Document 1).

JP 2013-183504 A

However, when a torque converter is disposed in the power transmission path between the driving force source and the drive wheels, simply controlling the output of the driving force source as described in Patent Document 1 is likely to cause changes in the input rotation speed of the torque converter, and when the input rotation speed changes, the torque transmitted from the torque converter to the gear mechanism also changes, causing the backlash elimination speed to change, making it difficult to adequately suppress the backlash shock.

The present invention was made against the background of the above circumstances, and its purpose is to appropriately suppress the rattle shock caused by backlash in the gear mechanism when a shift operation that reverses the drive direction is performed in a vehicle that has a torque converter disposed in the power transmission path.

In order to achieve this objective, the present invention relates to a vehicle having (a) a torque converter and a transmission arranged in series from the driving force source in a power transmission path between the driving wheels and the driving wheels, the transmission having at least a forward gear stage and a reverse gear stage, and a shift operation device that allows the driver to switch the transmission between the forward gear stage and the reverse gear stage, and (b) a control device for the vehicle having a backlash elimination control unit that controls the output of the driving force source to eliminate backlash in the gear mechanism subsequent to the transmission when a reverse shift operation is performed by the shift operation device to switch the transmission from one of the forward gear stage and the reverse gear stage to the other, and (c) the backlash elimination control unit controls the output of the driving force source so that the input rotational speed of the torque converter stagnates at a predetermined backlash elimination rotational speed for a predetermined period of time.

In such a vehicle control device, the output of the drive power source is controlled so that the input rotational speed of the torque converter remains at a predetermined backlash-reducing rotational speed for a predetermined period of time, so that the output torque of the torque converter, i.e., the torque transmitted to the gear mechanism, is stabilized and backlash in the gear mechanism can be appropriately eliminated to suppress rattle shock.

FIG. 1 is a schematic configuration diagram for explaining a drive system of a hybrid electric vehicle having a control device according to an embodiment of the present invention, and also shows control functions for various controls and essential parts of the control system. 4 is a flowchart specifically illustrating the operation of a garage control unit and a backlash reduction control unit that are functionally provided in the electronic control device of the hybrid electric vehicle of FIG. 1 . 3 is an example of a data map for determining a stagnation time tstuff for determining completion of backlash elimination in step S7 of FIG. 2. 3 is an example of a data map for determining the backlash-eliminating rotational speed Nstuff set in step S6 of FIG. 2. 3 is an example of a time chart illustrating changes in the operating state of each part when garage control and backlash elimination control are performed according to the flowchart of FIG. 2 during an R→D shift operation of the shift lever;

The present invention is preferably applied to electric vehicles equipped with a rotating machine as a driving force source, but can also be applied to engine-driven vehicles equipped with only an engine as a driving force source. Electric vehicles are electric vehicles equipped with only a rotating machine as a driving force source, and hybrid electric vehicles equipped with an engine and a rotating machine as driving force sources. As the rotating machine, a motor generator that can be used alternatively as an electric motor and a generator is preferably used, but an electric motor that does not function as a generator can also be used. The target vehicles include various drive types such as FR (front engine, rear drive) type rear-wheel drive vehicles, front and rear wheel drive vehicles with a transfer provided midway to distribute power to the front wheels, and FF (front engine, front drive) type front-wheel drive vehicles such as transaxles.

The transmission provided in series with the torque converter in the power transmission path has at least a forward gear and a reverse gear. A stepped transmission such as a planetary gear type or a parallel shaft type is preferably used, but it may also be a forward/reverse switching device. This transmission may be an automatic transmission that can electrically switch gears, or a manual transmission that mechanically switches gears according to the driver's operation of a shift lever. The gear mechanism after the transmission is a gear mechanism on the drive wheel side including the transmission, and includes various power transmission mechanisms with meshing gears, such as a differential gear that distributes power to the left and right drive wheels. The backlash-eliminating rotation speed may be set to a fixed value, but may also be variably set based on the vehicle conditions such as the oil temperature of the hydraulic oil in the torque converter and the type of gear of the transmission.

The present invention relates to an automatic transmission, for example: (a) the transmission is an automatic transmission in which the forward gear stage and the reverse gear stage are established by electrically switching the engagement and disengagement states of a plurality of engagement devices; (b) a garage control unit that performs a reverse range switching that electrically switches the automatic transmission from one of a D range, in which forward driving is possible using the forward gear stage, and an R range, in which reverse driving is possible using the reverse gear stage, to the other in accordance with the reverse shift operation when the reverse shift operation is performed; and (c) a creep control unit that controls the input rotation speed of the torque converter by the driving force source so as to obtain a predetermined creep torque when the automatic transmission is in the driving range of the D range or the R range, when the drive demand amount is approximately 0 and the vehicle speed is a low vehicle speed equal to or lower than a predetermined creep vehicle speed, or when the vehicle is stopped; (d) the garage control unit controls the output of the driving force source so that the input rotation speed of the torque converter becomes approximately 0 in priority to the control by the creep control unit, and performs the reverse range switching when the input rotation speed is approximately 0; and (e) The backlash eliminating control unit is configured to control the output of the driving force source so that the input rotation speed of the torque converter becomes the backlash eliminating rotation speed after the reverse range switching is performed, thereby executing backlash eliminating control. However, various aspects are possible, such as the input rotation speed of the torque converter not being set to 0, but being held at the backlash eliminating rotation speed, for example, and the reverse range switching by the garage control unit being performed. Also, the creep control unit is not necessarily required, and various aspects are possible, such as the input rotation speed of the torque converter being held at the backlash eliminating rotation speed until a driving force request is made, or the input rotation speed of the torque converter being temporarily set to 0 after the backlash eliminating control is completed.

For example, (a) the garage control unit can execute high-speed garage control in which the engagement command pressure of an engaging side engaging device to be engaged at the time of the reverse range switching is increased stepwise to quickly engage the engaging side engaging device, and normal garage control in which the engagement command pressure is gradually increased to gently engage the engaging side engaging device, and (b) the garage control unit is configured to execute the high-speed garage control when the reverse range switching is performed in a state where the input rotation speed is approximately 0. However, the manner of garage control by the garage control unit can be appropriately determined, such as using a garage control unit that performs reverse range switching only by normal garage control, and executing the normal garage control when the reverse range switching is performed in a state where the input rotation speed is approximately 0. High-speed garage control can also be executed in a state where the input rotation speed of the torque converter is set to, for example, a predetermined high-speed switching allowable rotation speed or less, which is lower than the backlash-reducing rotation speed.

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 for the purpose of explanation, and the dimensional ratios, angles, shapes, etc. of each part are not necessarily drawn accurately.

Figure 1 is a schematic diagram of the drive system of a hybrid electric vehicle 10 (hereinafter simply referred to as electric vehicle 10) having an electronic control device 90 as a vehicle control device according to one embodiment of the present invention, and shows the control functions for various controls in the electric vehicle 10 and the main parts of the control system. In Figure 1, the electric vehicle 10 is a parallel-type hybrid electric vehicle equipped with an engine 12 and a rotary machine MG as a driving force source for traveling. The electric vehicle 10 also has a power transmission device 16 provided in the power transmission path between the engine 12 and drive wheels 14. The drive wheels 14 are the left and right rear wheels, and the electric vehicle 10 is a FR-type rear-wheel drive vehicle.

The engine 12 is an internal combustion engine such as a gasoline engine or a diesel engine. The engine 12 has an engine control device 50 including a throttle actuator, a fuel injection device, an ignition device, etc., which is controlled by an electronic control device 90 to control the engine torque Te, which is the output torque of the engine 12. The rotating machine MG is a motor generator having a function as an electric motor that generates mechanical power from electric power and a function as a generator that generates electric power from mechanical power, such as a three-phase AC synchronous motor with a permanent magnet arranged on the rotor, and is connected to a battery 54 via an inverter 52. The rotating machine MG has an inverter 52 controlled by the electronic control device 90 to control the MG torque Tmg, which is the torque of the rotating machine MG, and the MG rotation speed Nmg, which is the rotation speed of the rotating machine MG. The rotating machine MG generates driving power using electric power supplied from the battery 54 via the inverter 52 instead of or in addition to the engine 12. The rotating machine MG also generates electricity by being regeneratively controlled to function as a generator when it is driven to rotate by the power of the engine 12 or the driven force input from the drive wheels 14, and generates regenerative braking when it is connected to the drive wheels 14. The electric power generated by the electric power generation of the rotating machine MG is stored in the battery 54 via the inverter 52. The battery 54 is an electricity storage device that supplies and receives electric power to the rotating machine MG.

The power transmission device 16 includes a K0 clutch 20, a torque converter 22, and an automatic transmission 24 in series from the engine 12 side in a case 18, which is a non-rotating member attached to the vehicle body, and a rotary machine MG is connected to the power transmission path between the K0 clutch 20 and the torque converter 22. The K0 clutch 20 is a clutch provided between the engine 12 and the rotary machine MG in the power transmission path between the engine 12 and the drive wheels 14, and is an engine disconnecting device that connects and disconnects the rotary machine MG and the engine 12. The torque converter 22 is a fluid-type transmission device provided between the rotary machine MG and the automatic transmission 24, and transmits power via hydraulic oil OIL, which is a fluid, and is connected to the engine 12 via the K0 clutch 20. The automatic transmission 24 is connected to the torque converter 22 and is interposed in the power transmission path between the torque converter 22 and the drive wheels 14. The power transmission device 16 includes a propeller shaft 28 connected to a transmission output shaft 26, which is an output rotating member of the automatic transmission 24, a differential gear 30 connected to the propeller shaft 28, and a pair of drive shafts 32 connected to the differential gear 30. The power transmission device 16 also includes an engine connecting shaft 34 connecting the engine 12 and the K0 clutch 20, an MG connecting shaft 36 connecting the K0 clutch 20 and the torque converter 22, and the rotor of the rotary machine MG is connected to the MG connecting shaft 36. The automatic transmission 24 and the differential gear 30 correspond to a gear mechanism that generates rattle shocks such as teeth rattle noise and torque fluctuations due to backlash of the gears when the electric vehicle 10 changes from driven to driven, or when the driving direction is reversed, i.e., when forward and reverse travel is switched.

The K0 clutch 20 is a wet or dry friction engagement device composed of, for example, a multi-plate or single-plate clutch pressed by an actuator. The K0 clutch 20 switches between control states such as an engaged state and an released state by changing the K0 torque Tk0, which is the torque capacity of the K0 clutch 20, by the adjusted K0 oil pressure PRk0 supplied from the hydraulic control circuit 56. The input side member of the K0 clutch 20 is connected to the engine connecting shaft 34 and rotated integrally with the engine connecting shaft 34. The output side member of the K0 clutch 20 is connected to the MG connecting shaft 36 and rotated integrally with the MG connecting shaft 36. When the K0 clutch 20 is in an engaged state, the rotor of the rotating machine MG and the pump impeller 22a are rotated integrally with the engine 12 via the engine connecting shaft 34. On the other hand, when the K0 clutch 20 is in a released state, the power transmission between the rotor of the rotating machine MG and the pump impeller 22a and the engine 12 is interrupted.

The rotary machine MG is connected to the MG connecting shaft 36 in the case 18 so as to be capable of transmitting power. The rotary machine MG is connected to the power transmission path between the engine 12 and the drive wheels 14, in particular to the power transmission path between the K0 clutch 20 and the torque converter 22 so as to be capable of transmitting power. In other words, the rotary machine MG is connected to the torque converter 22 and the automatic transmission 24 so as to be capable of transmitting power without passing through the K0 clutch 20. The torque converter 22 and the automatic transmission 24 transmit the driving force from the driving force sources of the engine 12 and the rotary machine MG to the drive wheels 14, respectively.

The torque converter 22 includes a pump wheel 22a connected to the MG connecting shaft 36, and a turbine wheel 22b connected to a transmission input shaft 38, which is an input rotating member of the automatic transmission 24. The pump wheel 22a is connected to the engine 12 via the K0 clutch 20, and is also directly connected to the rotary machine MG. The pump wheel 22a is an input member of the torque converter 22, and the turbine wheel 22b is an output member of the torque converter 22. The MG connecting shaft 36 is also an input rotating member of the torque converter 22. The transmission input shaft 38 is also an output rotating member of the torque converter 22, which is formed integrally with the turbine shaft that is driven to rotate by the turbine wheel 22b. The torque converter 22 includes an LU clutch 40 that connects the pump wheel 22a and the turbine wheel 22b. The LU clutch 40 is a direct clutch that connects the input and output rotating members of the torque converter 22, that is, a known lock-up clutch.

The LU clutch 40 switches between operating and control states by changing the LU clutch torque Tlu, which is the torque capacity of the LU clutch 40, with the regulated LU hydraulic pressure PRlu supplied from the hydraulic control circuit 56. The control states of the LU clutch 40 include a fully released state in which the LU clutch 40 is released, a slip state in which the LU clutch 40 is engaged with slippage, and a fully engaged state in which the LU clutch 40 is engaged. By placing the LU clutch 40 in the fully released state, the torque converter 22 is placed in a torque converter state in which a torque amplification effect is obtained. Also, by placing the LU clutch 40 in the fully engaged state, the torque converter 22 is placed in a lock-up state in which the pump impeller 22a and the turbine impeller 22b are rotated together.

The automatic transmission 24 is a known planetary gear type automatic transmission that includes, for example, one or more planetary gear devices and multiple engagement devices CB. The engagement devices CB are hydraulic friction engagement devices that are composed of, for example, multi-plate or single-plate clutches or brakes pressed by a hydraulic actuator, or band brakes tightened by a hydraulic actuator. The engagement devices CB have their respective torque capacities, or CB torques Tcb, changed by the regulated CB hydraulic pressure PRcb supplied from the hydraulic control circuit 56, thereby switching between control states such as an engaged state and a disengaged state.

The automatic transmission 24 is a stepped transmission that can form multiple forward and reverse gears with different gear ratios γat (=AT input rotation speed Ni /AT output rotation speed No) by engaging any of the engagement devices CB. The automatic transmission 24 selectively forms multiple gears by switching the gears formed according to the driver's (=operator's) accelerator operation and the vehicle speed V, etc., by the electronic control device 90. In addition, when all of the engagement devices CB are released, the transmission is in neutral, which cuts off the power transmission. The AT input rotation speed Ni is the rotation speed of the transmission input shaft 38 and is the input rotation speed of the automatic transmission 24. The AT input rotation speed Ni is also the rotation speed of the output rotating member of the torque converter 22, and is the same value as the turbine rotation speed Nt, which is the output rotation speed of the torque converter 22. The AT output rotation speed N0 is the rotation speed of the transmission output shaft 26, and is the output rotation speed of the automatic transmission 24.

In the power transmission device 16, when the K0 clutch 20 is engaged, the power output from the engine 12 is transmitted from the engine connecting shaft 34 to the drive wheels 14 via the K0 clutch 20, MG connecting shaft 36, torque converter 22, automatic transmission 24, propeller shaft 28, differential gear 30, drive shaft 32, etc. In addition, the power output from the rotary machine MG is transmitted from the MG connecting shaft 36 to the drive wheels 14 via the torque converter 22, automatic transmission 24, propeller shaft 28, differential gear 30, drive shaft 32, etc., regardless of the control state of the K0 clutch 20.

The electric vehicle 10 is equipped with a mechanical oil pump MOP 58, an electric oil pump EOP 60, a pump motor 62, etc. The MOP 58 is connected to the pump impeller 22a and is rotated and driven by a driving force source (engine 12, rotary machine MG) to discharge hydraulic oil OIL used in the power transmission device 16. The pump motor 62 is an electric motor dedicated to the EOP 60 for rotating and driving the EOP 60. The EOP 60 is rotated and driven by the pump motor 62 to discharge hydraulic oil OIL, and can discharge hydraulic oil OIL at any timing including when the electric vehicle 10 is stopped. The hydraulic oil OIL discharged by the MOP 58 and EOP 60 is supplied to the hydraulic control circuit 56. The hydraulic control circuit 56 outputs the CB hydraulic pressure PRcb, the K0 hydraulic pressure PRk0, the LU hydraulic pressure PRlu, etc., which are adjusted based on the hydraulic oil OIL discharged by the MOP 58 and/or the EOP 60. The hydraulic oil OIL is supplied to the torque converter 22 for power transmission, and is also used for lubrication and cooling of various parts. The hydraulic oil OIL is stored in an oil reservoir such as an oil pan provided at the bottom of the case 18, and is pumped up by the MOP 58 and/or the EOP 60 and supplied to the hydraulic control circuit 56.

The electric vehicle 10 is equipped with an electronic control device 90 as a control device that executes various types of control. The electronic control device 90 is configured to include a so-called microcomputer equipped with, for example, a CPU, RAM, ROM, an input/output interface, etc., and the CPU executes various types of control of the electric vehicle 10 by performing signal processing according to a program previously stored in the ROM while utilizing the temporary storage function of the RAM. The electronic control device 90 is configured to include computers for engine control, MG control, hydraulic control, etc. as necessary.

The electronic control device 90 receives various signals based on detection values from various sensors (e.g., engine rotation speed sensor 70, turbine rotation speed sensor 72, output rotation speed sensor 74, MG rotation speed sensor 76, accelerator opening sensor 78, throttle valve opening sensor 80, brake switch 82, battery sensor 84, oil temperature sensor 86, lever position sensor 88, etc.) provided in the electric vehicle 10 (e.g., engine rotation speed Ne, which is the rotation speed of the engine 12; turbine rotation speed Nt, which is the same value as the AT input rotation speed Ni; AT output rotation speed No, which corresponds to the vehicle speed V; MG rotation speed Nmg, which is the rotation speed of the rotating machine MG; accelerator opening θacc, such as the accelerator operation amount representing the driving request amount of the driver; throttle valve opening θth, which is the opening of the electronic throttle valve; brake ON signal Bon, which is a signal indicating a state in which the brake pedal for operating the wheel brakes is being operated by the driver; battery temperature THbat, battery charge/discharge current Ibat, and battery voltage Vbat of the battery 54). , the oil temperature THoil, which is the temperature of the hydraulic oil OIL in the hydraulic control circuit 56, and a signal indicating the operation position POSsh of the shift lever 64 provided in the electric vehicle 10 are supplied. The MG rotation speed Nmg is equal to the input rotation speed Ntci of the torque converter 22, and the turbine rotation speed Nt is equal to the output rotation speed Ntco of the torque converter 22.

The shift lever 64 is disposed near the driver's seat and is a shift operation member operated by the driver to switch the shift range, which is the power transmission state of the automatic transmission 24, and has multiple operation positions POSsh. As the operation positions POSsh, multiple positions, for example, P, R, N, and D, are provided. The P position is an operation position for selecting the P (parking) range for parking, in which the automatic transmission 24 is in a neutral state in which the power transmission is cut off and the rotation of the transmission output shaft 26 is mechanically prevented. The neutral state is, for example, a state in which all the engagement devices CB of the automatic transmission 24 are released. The R position is an operation position for selecting the R (reverse) range for reverse driving, in which the automatic transmission 24 is in reverse gear. The N position is an operation position for selecting the N (neutral) range, in which the automatic transmission 24 is in a neutral state, similar to the P position. The D position is an operating position that selects the D (drive) range for forward travel, in which the automatic transmission 24 automatically switches between multiple forward gears depending on the driving conditions such as the vehicle speed V and the accelerator opening θacc. The shift lever 64 may be one that is positioned and held at each of the operating positions P, R, N, and D POSsh, or it may be an automatic return type that is automatically returned to a predetermined home position. In addition, a push button switch or the like that selects each of the above shift ranges may be used as the shift operating member.

The electronic control device 90 outputs various command signals (e.g., engine control command signal Se for controlling the engine 12, MG control command signal Smg for controlling the rotary machine MG, CB hydraulic control command signal Scb for controlling the engagement device CB, K0 hydraulic control command signal Sk0 for controlling the K0 clutch 20, LU hydraulic control command signal Slu for controlling the LU clutch 40, EOP control command signal Seop for controlling the EOP 60, etc.) to each device (e.g., engine control device 50, inverter 52, hydraulic control circuit 56, pump motor 62, etc.) provided in the electric vehicle 10. The hydraulic control circuit 56 is provided with a plurality of solenoid valves that switch oil paths and control hydraulic pressure according to the CB hydraulic control command signal Scb, K0 hydraulic control command signal Sk0, and LU hydraulic control command signal Slu.

The electronic control unit 90 functionally comprises a hybrid control unit 92, a gear shift control unit 94, a creep control unit 96, and a backlash elimination control unit 98 to realize various controls in the electric vehicle 10.

The hybrid control unit 92 has a function of controlling the operation of the rotary machine MG and the engine 12 in a coordinated manner. The hybrid control unit 92 calculates the driving demand amount of the electric vehicle 10 by the driver, for example, by applying the accelerator opening θacc and the vehicle speed V to a driving demand amount map. The driving demand amount is, for example, the required driving torque Trdem at the driving wheels 14. The hybrid control unit 92 calculates the required input torque Tindem, which is the input torque of the torque converter 22 required to realize the above-mentioned required driving torque Trdem, taking into account the transmission loss, the auxiliary load, the gear ratio γat of the automatic transmission 24, the torque ratio of the torque converter 22, the chargeable power Win and the dischargeable power Wout of the battery 54, etc., and outputs an engine control command signal Se for controlling the engine 12 and an MG control command signal Smg for controlling the rotary machine MG so that the required input torque Tindem is obtained. The chargeable power Win and dischargeable power Wout of the battery 54 are calculated by the electronic control unit 90 based on, for example, the battery temperature THbat and the state of charge value SOC [%] of the battery 54. The state of charge value SOC of the battery 54 is a value indicating the state of charge of the battery 54, i.e., the remaining amount of electricity, and can be calculated based on, for example, the battery charge/discharge current Ibat and the battery voltage Vbat.

When the required input torque Tindem can be met only by the output of the rotating machine MG, the hybrid control unit 92 sets the vehicle to a BEV (Battery Electric Vehicle) driving mode, which is a motor driving mode in which the rotating machine MG is driven only by the power from the battery 54. In the BEV driving mode, the K0 clutch 20 is opened to stop the engine 12, and the vehicle is driven by the rotating machine MG only as a driving force source. In this BEV driving mode, the MG torque Tmg is controlled to realize the required input torque Tindem. On the other hand, when the required input torque Tindem cannot be met without using at least the output of the engine 12, the hybrid control unit 92 sets the vehicle to an HEV (Hybrid Electric Vehicle) driving mode, which is an engine driving mode. In the HEV driving mode, the K0 clutch 20 is engaged to drive the vehicle by using at least the engine 12 as a driving force source, i.e., HEV driving. In this HEV driving mode, the engine torque Te is controlled to realize all or part of the required input torque Tindem, and the MG torque Tmg is controlled to compensate for the torque that is insufficient for the required input torque Tindem by the engine torque Te. On the other hand, even if the required input torque Tindem can be met only by the output of the rotary machine MG, the hybrid control unit 92 establishes the HEV driving mode when the engine 12 or the like needs to be warmed up. In this way, the hybrid control unit 92 switches between the BEV driving mode and the HEV driving mode by automatically stopping the engine 12 during HEV driving, restarting the engine 12 after the engine has been stopped, starting the engine 12 during BEV driving, automatically stopping the engine 12 while the vehicle is stopped, and starting the engine 12, based on the required input torque Tindem, etc.

The shift control unit 94 includes a garage control unit 94a that switches the shift range of the automatic transmission 24 according to the operation position POSsh selected by the shift operation when the shift lever 64 is operated while the electric vehicle 10 is substantially stopped. When a reverse shift operation is performed in which the shift lever 64 is switched from one of the D position and the R position to the other, the garage control unit 94a performs reverse range switching to switch the automatic transmission 24 from one of the D range and the R range to the other according to the reverse shift operation, and also performs various range switching to switch the shift range between the non-driving range of the P range and the N range and the driving range of the D range and the R range. The reverse shift operation is specifically a D → R shift operation from the D position to the R position, or an R → D shift operation from the R position to the D position, and may be performed via the N position. When a D→R shift operation is performed, the garage control unit 94a performs a reverse range switch to switch the automatic transmission 24 from D range to R range, i.e., a D→R range switch that outputs a CB hydraulic control command signal Scb to the hydraulic control circuit 56 to switch from a forward gear to a reverse gear. Also, when an R→D shift operation is performed, the garage control unit 94a performs a reverse range switch to switch the automatic transmission 24 from R range to D range, i.e., a R→D range switch that outputs a CB hydraulic control command signal Scb to the hydraulic control circuit 56 to switch from a reverse gear to a forward gear.

For example, among the multiple engagement devices CB of the automatic transmission 24, the first engagement device CB1 and the second engagement device CB2 are engaged to form a first gear stage with the largest gear ratio γat among the multiple forward gear stages, and the automatic transmission 24 is in the D range. When the second engagement device CB2 and the third engagement device CB3 are engaged to form a reverse gear stage and the automatic transmission 24 is in the R range, in the D → R range switching, the hydraulic pressures PRcb1, PRcb3 of the first engagement device CB1 are controlled to release the first engagement device CB1 and engage the third engagement device CB3. In addition, in the R → D range switching, the hydraulic pressures PRcb3, PRcb1 of the third engagement device CB3 are controlled to release the third engagement device CB3 and engage the first engagement device CB1.

Here, when any of the multiple engagement devices CB is engaged during range switching including reverse range switching, the garage control unit 94a has a function of performing normal garage control in which the engagement command pressure of the hydraulic pressure PRcon of the engagement side engagement device CBcon is gradually increased to smoothly engage the engagement side engagement device CBcon, as well as a function of performing high-speed garage control in which the engagement command pressure of the hydraulic pressure PRcon of the engagement side engagement device CBcon is increased in a stepwise manner to quickly engage the engagement side engagement device CBcon and execute range switching in a short time. For example, in the D→R range switching, the third engagement device CB3 is the engagement side engagement device CBcon, and the engagement command pressure of the hydraulic pressure PRcb3 of the third engagement device CB3 is gradually increased at a predetermined increase rate in normal garage control, while it is increased in a stepwise manner in high-speed garage control. In addition, in the R→D range change, the first engagement device CB1 is the engagement side engagement device CBcon, and the engagement command pressure of the hydraulic pressure PRcb1 of the first engagement device CB1 is gradually increased at a predetermined increase rate in normal garage control, while it is increased in a stepwise manner in high-speed garage control. Figure 5 is an example of a time chart when the R→D range change is performed by high-speed garage control in conjunction with the R→D shift operation. After lowering the hydraulic pressure PRcb3 of the third engagement device CB3, which is the disengagement side engagement device CBop, the engagement command pressure of the hydraulic pressure PRcb1 of the first engagement device CB1, which is the engagement side engagement device CBcon, is increased in a stepwise manner, so that the first engagement device CB1 can be quickly engaged and the R→D range change can be performed in a short time. In Figure 5, the first engagement device CB1 is approximately engaged at time t2.

When the D range is selected, the gear shift control unit 94 also performs gear shift control by using a predetermined gear shift map or the like with the driving conditions such as the vehicle speed V and the accelerator opening θacc as variables to determine whether to shift the automatic transmission 24, and by outputting a CB hydraulic control command signal Scb to the hydraulic control circuit 56 as necessary to automatically switch between multiple forward gears of the automatic transmission 24.

The creep control unit 96 executes creep torque control to control the input rotation speed Ntci (=Nmg) of the torque converter 22 by the driving force source so that a predetermined creep torque Tcreep is obtained as the driving torque Tr of the electric vehicle 10 when the accelerator opening θacc corresponding to the driving demand amount is approximately 0 and the vehicle speed V is at or below a predetermined creep vehicle speed or when the vehicle is stopped, with the shift lever 64 in the driving position of D or R and the automatic transmission 24 in the driving range of D or R. In this embodiment, with the K0 clutch 20 open and the engine 12 disconnected from the power transmission path, the rotating machine MG is controlled to generate creep torque Tcreep via the torque converter 22. That is, when the LU clutch 40 is in a completely open state and power is transmitted from the MG connecting shaft 36 to the transmission input shaft 38 side via the torque converter 22, the MG torque Tmg is controlled so that the input rotation speed Ntci of the torque converter 22 becomes a predetermined creep rotation speed Ncreep, thereby generating a predetermined creep torque Tcreep. The creep rotation speed Ncreep is set to a rotation speed approximately equal to the idle rotation speed Neidl of the engine 12, for example, but may be set independently regardless of the idle rotation speed Neidl. Also, different creep rotation speeds Ncreep may be set for the D range and the R range, or may be variably set according to the oil temperature THoil of the hydraulic oil OIL flowing through the torque converter 22. The predetermined creep torque Tcreep can also be generated by engaging the K0 clutch 20 and operating the engine 12 at the idle rotation speed Neidl, etc.

When the shift lever 64 is shifted from D to R or from R to D, the clearance eliminating control unit 98 controls the output of the driving force source to eliminate clearance in the automatic transmission 24 and the differential gear 30, which are the gear mechanism. That is, in this embodiment, when the accelerator opening θacc corresponding to the driving demand amount is approximately 0 and the vehicle speed V is at a low vehicle speed below a predetermined creep vehicle speed or when the vehicle is stopped, the creep control unit 96 controls the rotating machine MG to generate a predetermined creep torque Tcreep. Therefore, when the forward and reverse gear stages of the automatic transmission 24 are switched with the reverse range switching from D to R or from R to D, the creep torque Tcreep is reversed, and a rattle shock may occur due to the backlash of each part of the automatic transmission 24 and the differential gear 30. For this reason, the creep torque Tcreep is temporarily limited to perform backlash elimination control to smoothly eliminate backlash in the automatic transmission 24 and the differential gear 30. Specifically, backlash elimination control is performed to control the MG torque Tmg so that the input rotation speed Ntci of the torque converter 22 stagnates for a predetermined time at a predetermined backlash elimination rotation speed Nstuff that is lower than the creep rotation speed Ncreep at which the creep torque Tcreep is obtained. When the input rotation speed Ntci is reduced in this manner, the output torque of the torque converter 22, i.e., the torque transmitted to the automatic transmission 24 and the differential gear 30, is reduced, and the backlash elimination speed associated with the reversal of the rotation direction is reduced, suppressing the rattle shock. The backlash elimination rotation speed Nstuff is appropriately determined by experiments, simulations, etc. so that backlash elimination is performed smoothly.

Figure 2 is a flow chart specifically explaining the garage control executed by the garage control unit 94a and the backlash eliminating control executed by the backlash eliminating control unit 98, and signal processing is executed according to steps S1 to S9 (hereinafter, steps are omitted and simply referred to as S1 to S9). Here, in priority to the creep torque control by the creep control unit 96, the garage control unit 94a controls the MG torque Tmg so that the input rotation speed Ntci of the torque converter 22 becomes approximately 0, and in a state where the input rotation speed Ntci is approximately 0, the garage control unit 94a executes reverse range switching. Thereafter, the backlash eliminating control unit 98 executes backlash eliminating control, and the MG torque Tmg is controlled so that the input rotation speed Ntci stagnates for a predetermined time at a predetermined backlash eliminating rotation speed Nstuff that is lower than the creep rotation speed Ncreep. Then, when the backlash eliminating control is completed, normal control by the creep control unit 96 and the like is permitted. S2 to S4 and S9 in FIG. 2 correspond to the garage control unit 94a, and S6 and S7 correspond to the backlash elimination control unit 98.

2 is executed in a driving state where a rattle shock may occur due to creep torque Tcreep, for example, when the accelerator opening θacc corresponding to the drive demand amount is approximately 0 and the vehicle speed V is a low vehicle speed below a predetermined creep vehicle speed or when the vehicle is stopped. In S1 of FIG. 2, it is determined whether a shift operation to change the operating position POSsh of the shift lever 64 has been performed, for example, based on the operating position POSsh. If a shift operation has not been performed, the process ends, but if a shift operation has been performed, S2 and subsequent steps are executed. In S2, it is determined whether creep cut is possible to set the creep torque Tcreep to approximately 0 in priority to the creep torque control by the creep control unit 96, based on whether a predetermined creep cut permission condition is satisfied. The creep cut permission condition is, for example, when a brake ON signal Bon is supplied so that the electric vehicle 10 does not slide down due to creep cut, when the road gradient is below a predetermined value, when the vehicle speed V is below a predetermined vehicle speed, etc.

If the creep cut permission condition is not met, i.e., if the judgment in S2 is NO (negative), S9 is executed and the garage control unit 94a performs range switching using normal garage control without performing creep cut. In other words, when performing range switching in conjunction with a shift operation, if it is necessary to engage any of the engagement devices CB, the engagement command pressure for that engagement side engagement device CBcon is gradually increased to smoothly engage the engagement side engagement device CBcon.

If the judgment in S2 is YES (affirmative), that is, if the creep cut permission condition is satisfied, S3 is executed to control the MG torque Tmg so that the input rotation speed Ntci of the torque converter 22 becomes 0. That is, in priority to the creep torque control by the creep control unit 96, the MG torque Tmg is controlled so that the input rotation speed Ntci decreases at a predetermined rate of change to 0. As a result, the creep torque Tcreep becomes 0, the driving torque Tr of the electric vehicle 10 becomes 0, and the torque transmitted to the automatic transmission 24 and the differential gear 30 in the power transmission path also becomes 0. Then, in this state, the high-speed garage control in S4 is executed. Specifically, when it is necessary to engage any of the engagement devices CB when performing range switching in conjunction with a shift operation, the engagement command pressure of the engagement side engagement device CBcon is increased in a stepwise manner to quickly engage the engagement side engagement device CBcon. For example, when performing a reverse range switch to switch between R and D ranges with a reverse shift operation, the hydraulic pressure PRop of the disengagement engagement device CBop is lowered, and then the engagement command pressure of the hydraulic pressure PRcon of the engagement engagement device CBcon is increased in a stepped manner, so that the engagement engagement device CBcon is quickly engaged and the reverse range switch can be performed in a short time.

Figure 5 is an example of a time chart showing the change in the operating state of each part when the R → D range switching is performed according to the flowchart of Figure 2 with the R → D shift operation, and time t1 is the time when the R → D shift operation is performed by the shift lever 64. Figure 5 shows the case where the creep cut permission condition is satisfied, the judgment in S2 is YES, and in S3, the input rotation speed Ntci is reduced to 0 at a predetermined change rate by the control of the rotating machine MG, and the creep torque Tcreep becomes 0. In addition, in S4, high-speed garage control is performed, and after the hydraulic pressure PRcb3 of the third engagement device CB3, which is the disengagement side engagement device CBop, is reduced, the engagement command pressure of the hydraulic pressure PRcb1 of the first engagement device CB1, which is the engagement side engagement device CBcon, is increased in a stepwise manner. As a result, the first engagement device CB1 is quickly engaged, and the R → D range switching is performed in a short time. Since the creep torque Tcreep is 0 and the transmission torque of the automatic transmission 24 is 0, there is no risk of shift shock occurring despite the sudden engagement of the first engagement device CB1. Time t2 is the time when the first engagement device CB1 is engaged and switched to the D range. Note that the input rotation speed Ntci does not necessarily have to be completely 0. If the output torque of the torque converter 22, i.e., the transmission torque of the automatic transmission 24, becomes approximately 0, shock due to sudden engagement of the engagement side engagement device CBcon can be sufficiently reduced.

Returning to FIG. 2, in the next step S5, it is determined whether the driving direction is reversed, i.e., whether the shift operation of the shift lever 64 is a reverse shift operation. If it is not a reverse shift operation, S8 is immediately executed to increase the input rotation speed Ntci to the target input rotation speed Ntcit. The target input rotation speed Ntcit is determined based on, for example, the shift range after range switching of the automatic transmission 24 and the required driving torque Trdem, but in this embodiment, creep torque control by the creep control unit 96 is permitted, so that, for example, when the accelerator opening θacc is 0 in the driving range of the D range or the R range, the creep rotation speed Ncreep is set to the target input rotation speed Ntcit.

If the determination in S5 is YES, that is, if the shift operation of the shift lever 64 is a reverse shift operation and the reverse range switching is performed in S4, S6 is executed. In S6, the MG torque Tmg is controlled so as to increase the input rotation speed Ntci to a predetermined clearance rotation speed Nstuff lower than the creep rotation speed Ncreep at a predetermined change rate. In addition, in S7, it is determined whether clearance has been completed, in this embodiment, whether the clearance rotation speed Nstuff has been continuously maintained for a predetermined stagnation time tstuff, and by executing S6 until the stagnation time tstuff is reached, the MG torque Tmg is controlled so that the state of the input rotation speed Ntci = Nstuff is continued. Then, when the stagnation time tstuff is reached, S8 is executed and the input rotation speed Ntci is changed to the target input rotation speed Ntcit at a predetermined change rate. In this way, by stagnating the input rotation speed Ntci of the torque converter 22 for a predetermined time at the clearance-reducing rotation speed Nstuff, which is lower than the creep rotation speed Ncreep, the output torque of the torque converter 22, i.e., the torque transmitted to the automatic transmission 24 and the differential gear 30, is stabilized, and clearance of the automatic transmission 24 and the differential gear 30 can be appropriately performed so that rattle shock is suppressed. Note that the completion of clearance elimination in S7 can also be determined not by the stagnation time tstuff but by, for example, a change in the MG torque Tmg of the rotary machine MG that controls the input rotation speed Ntci.

Time t3 in Figure 5 is the time when the input rotational speed Ntci is increased to the backlash-removing rotational speed Nstuff by executing S6, and time t4 is the time when the state of input rotational speed Ntci = Nstuff reaches the stagnation time tstuff. Between times t3 and t4, the backlash changes from the R side to the D side, which represents the backlash removal. After that, in Figure 5, the target input rotational speed Ntcit is set to the creep rotational speed Ncreep, and the MG torque Tmg is controlled so that the input rotational speed Ntci is increased to the creep rotational speed Ncreep at a predetermined rate of change, thereby obtaining a predetermined creep torque Tcreep.

Here, the clearance-reducing rotation speed Nstuff and the stagnation time tstuff may each be set to a fixed value in advance, but when the oil temperature THoil of the hydraulic oil OIL supplied to the torque converter 22 is low, the viscosity increases, the output torque of the torque converter 22 increases, the torque transmitted to the gear mechanism such as the automatic transmission 24 increases, and the clearance-reducing speed increases. For this reason, at least one of the clearance-reducing rotation speed Nstuff and the stagnation time tstuff may be set according to the oil temperature THoil of the hydraulic oil OIL. For example, as shown in FIG. 3, when the oil temperature THoil is low, the stagnation time tstuff for clearance can be shortened continuously or stepwise compared to when the oil temperature THoil is high, thereby shortening the time required for clearance. In addition, since the clearance-reducing speed is faster, the clearance-reducing rotation speed Nstuff can be lowered continuously or stepwise compared to when the oil temperature THoil is high, for example, as shown in FIG. 4, when the oil temperature THoil is low, the clearance-reducing rotation speed Nstuff can be lowered continuously or stepwise compared to when the oil temperature THoil is high, thereby reliably suppressing the clearance shock. In order to reduce the rattle shock while shortening the time required to eliminate rattle, both the rattle eliminating rotation speed Nstuff and the stagnation time tstuff may be changed to optimal values according to the oil temperature THoil of the hydraulic oil OIL.

In addition, when the forward gear stage and the reverse gear stage have different speed ratios γat, the torque transmitted to the gear mechanism after the automatic transmission 24 changes accordingly, and the clearance speed changes. For this reason, at least one of the clearance clearance rotation speed Nstuff and the stagnation time tstuff may be determined according to the type of reverse range switching, i.e., R → D range switching or D → R range switching. For example, when the speed ratio γat of the reverse gear stage is larger than that of the forward gear stage, the torque transmitted to the gear mechanism after the automatic transmission 24 becomes relatively large in the D → R range switching, and the clearance clearance speed becomes faster, so that the clearance clearance time can be shortened by shortening the stagnation time tstuff compared to the R → D range switching. In addition, since the clearance clearance speed becomes faster, the clearance shock is more likely to occur, so that the clearance shock can be reliably suppressed by lowering the clearance clearance rotation speed Nstuff in the D → R range switching compared to the R → D range switching. That is, the stagnation time tstuff of the backlash eliminating control with a larger gear ratio γat can be made shorter than that of the backlash eliminating control with a smaller gear ratio γat, and the backlash eliminating rotation speed Nstuff of the backlash eliminating control with a larger gear ratio γat can be made lower than that of the backlash eliminating control with a smaller gear ratio γat. Both the backlash eliminating rotation speed Nstuff and the stagnation time tstuff can be changed to optimal values according to the type of reverse range switching so that the backlash eliminating time is shortened while suppressing the rattle shock.

In this way, the backlash-eliminating control section 98 of the electronic control device 90 of the electric vehicle 10 of this embodiment controls the MG torque Tmg so that the input rotation speed Ntci of the torque converter 22 stagnates at the predetermined backlash-eliminating rotation speed Nstuff for a predetermined period of time, so that the output torque of the torque converter 22, i.e., the torque transmitted to the automatic transmission 24 and the differential gear 30, which are the gear mechanisms, is stabilized, and backlash elimination of the automatic transmission 24 and the differential gear 30 can be appropriately performed so that rattle shock is suppressed.

The above describes in detail an embodiment of the present invention based on the drawings, but this 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 electric vehicle (vehicle) 12: Engine (power source) 14: Drive wheels 16: Power transmission device (power transmission path) 22: Torque converter 24: Automatic transmission (transmission, gear mechanism) 30: Differential gear (gear mechanism) 64: Shift lever (shift operation device) 90: Electronic control device (control device) 98: Backlash elimination control unit MG: Rotating machine (power source) Ntci: Input rotation speed Nstuff: Backlash elimination rotation speed tstuff: Stagnation time (predetermined time)

Claims (1)

A vehicle in which a torque converter and a transmission are arranged in series from a driving force source side in a power transmission path between the driving force source and driving wheels, the transmission having at least a forward gear stage and a reverse gear stage, and a shift operation device that can switch the transmission between the forward gear stage and the reverse gear stage by an operation of a driver,
a backlash eliminating control unit that controls an output of the driving force source to eliminate backlash in a gear mechanism subsequent to the transmission when a reverse shift operation is performed by the shift operation device to switch the transmission from one of the forward gear stage and the reverse gear stage to the other,
The vehicle control device, wherein the backlash-eliminating control unit controls an output of the driving force source so that an input rotation speed of the torque converter remains at a predetermined backlash-eliminating rotation speed for a predetermined period of time.

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