Vehicle control device

Abstract

To curb an increase in a temperature of hydraulic oil due to a reduction in cooling performance of a heat exchanger while appropriately maintaining follow-up travel.SOLUTION: During execution of follow-up travel in which a vehicle automatically travels with a predetermined inter-vehicle distance from a preceding vehicle, oil temperature curbing control is executed to change a control state of a lockup clutch so as to curb an increase in a temperature of hydraulic oil which is distributed inside a fluid type transmission device and used for switching the control state of the lockup clutch. In this way, a heat generation amount of the fluid type transmission device including the lockup clutch can be reduced without changing an actual inter-vehicle distance with respect to a predetermined inter-vehicle distance in the follow-up travel. Thus, a vehicle control device can curb the increase in the temperature of the hydraulic oil due to a reduction in cooling performance of a heat exchanger while appropriately maintaining the follow-up travel.SELECTED DRAWING: Figure 8

Description

[Technical field]

[0001] The present invention relates to a vehicle control device for controlling following travel. [Background technology]

[0002] There are well-known vehicle control devices that automatically control following a vehicle at a predetermined distance from a preceding vehicle. For example, there is a vehicle driving control device described in Patent Document 1. Patent Document 1 discloses that when the inflow air flow rate blown into the vehicle interior is less than the required air flow rate, the inflow air flow rate is increased by moving at least a part of the portion that introduces air into the vehicle interior away from the separation area where the air flow rate is reduced, which occurs behind the preceding vehicle. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2012-201133 A Summary of the Invention [Problem to be solved by the invention]

[0004] In following driving, the preceding vehicle acts as a windbreak, reducing the air flow rate hitting the following vehicle and reducing running resistance. On the other hand, the cooling performance of the heat exchanger using air is reduced. The reduction in cooling performance may lead to an increase in temperature of the object cooled by the heat exchanger, for example. The object is hydraulic oil that flows through a fluid-type transmission device having a lock-up clutch and is provided in the power transmission path between the power source and the driving wheels and is used to switch the control state of the lock-up clutch. The increase in temperature of the hydraulic oil may lead to deterioration of the hydraulic oil, for example. As disclosed in Patent Document 1, if the state of following driving is changed, such as by lengthening the inter-vehicle distance from a predetermined inter-vehicle distance, to suppress the reduction in the inflow air flow rate, the reduction in the cooling performance of the heat exchanger is suppressed, but the running resistance increases.

[0005] The present invention has been made against the background of the above circumstances, and its object is to provide a vehicle control device that can suppress the rise in hydraulic oil temperature caused by a decrease in the cooling performance of the heat exchanger while properly maintaining following driving. [Means for solving the problem]

[0006] The gist of a first aspect of the present invention is a control device for a vehicle including (a) a power source and a hydrodynamic power transmission having a lock-up clutch provided in a power transmission path between the power source and driving wheels, the control device including: (b) a follow-up running control unit that controls follow-up running in which the vehicle automatically runs at a predetermined distance from a preceding vehicle; and (c) a lock-up clutch control unit that controls the lock-up clutch to be in one of a released state, a slip state, and an engaged state, and (d) the lock-up clutch control unit executes oil temperature suppression control that changes the control state of the lock-up clutch so as to suppress a temperature rise of hydraulic oil that circulates within the hydrodynamic power transmission and is used to switch the control state of the lock-up clutch during the follow-up running. (e) the lock-up clutch control unit sets a lower predetermined oil temperature as the temperature of the hydraulic oil increases, and when it is determined that the temperature of the hydraulic oil is equal to or higher than the predetermined oil temperature, executes the oil temperature suppression control so as to reduce the amount of heat generated by the fluid-type power transmission device. The point is...

[0007] In addition, a second invention is a vehicle control device according to the first invention, wherein the oil temperature suppression control is a control that switches the lock-up clutch, which is controlled to the released state or the slip state based on a predetermined relationship, to the engaged state.

[0008] Also, the third invention The gist of the present invention is a control device for a vehicle including: (a) a power source; and a fluid-type power transmission device having a lock-up clutch provided in a power transmission path between the power source and drive wheels, (b) a follow-up driving control unit that controls follow-up driving in which the vehicle automatically drives at a predetermined distance from a preceding vehicle; and (c) a lock-up clutch control unit that controls the lock-up clutch to be in one of a released state, a slip state, and an engaged state, (d) the lock-up clutch control unit executes oil temperature suppression control that changes the control state of the lock-up clutch so as to suppress a temperature rise of hydraulic oil that circulates through the fluid-type power transmission device and is used to switch the control state of the lock-up clutch during the follow-up driving, and (e) The oil temperature suppression control is a control that switches the lock-up clutch, which is controlled to the released state based on a predetermined relationship, to the engaged state, and switches the lock-up clutch, which is controlled to the slip state based on the relationship, to the released state.

[0009] The fourth invention is the above Record number 3rd shot ClearlyIn the described vehicle control device, the lock-up clutch control unit sets a lower predetermined oil temperature the more easily the temperature of the hydraulic oil increases, and when it determines that the temperature of the hydraulic oil is above the predetermined oil temperature, it executes the oil temperature suppression control to reduce the amount of heat generated from the fluid transmission device.

[0010] The fifth invention is the above-mentioned The first invention, the second invention, and The fourth invention Any one of In the vehicle control device described in the above, the ease with which the temperature of the hydraulic oil increases is varied depending on the environment of the driving route predicted for future travel, and the lock-up clutch control unit sets the specified oil temperature based on environmental information of the driving route.

[0011] In addition, a sixth aspect of the present invention is that in the vehicle control device described in the fifth aspect of the present invention, the lock-up clutch control unit calculates the vehicle load predicted for future driving based on environmental information of the driving route, and sets the specified oil temperature to a lower value as the vehicle load becomes greater.

[0012] The seventh invention is the above-mentioned The first invention, the second invention, and The fourth invention Any one of In the vehicle control device described in the above, the ease with which the temperature of the hydraulic oil increases is varied depending on the vehicle-to-vehicle distance from the preceding vehicle, and the lock-up clutch control unit sets the specified oil temperature to a lower value as the vehicle-to-vehicle distance becomes shorter.

[0013] The eighth aspect of the present invention is the above-mentioned The first invention, the second invention, and The fourth invention Any one of In the vehicle control device described in the above, the ease with which the temperature of the hydraulic oil increases is varied depending on the projected area of ​​the preceding vehicle, and the lock-up clutch control unit sets the specified oil temperature to a lower value the larger the projected area of ​​the preceding vehicle when viewed from behind.

[0014] The ninth aspect of the present invention is the above-mentioned The first invention, the second invention, and The fourth invention Any one ofIn the vehicle control device described in the above, the ease with which the temperature of the hydraulic oil increases is varied depending on the width of the leading vehicle, which is the vehicle dimension in a direction horizontally perpendicular to the direction of travel of the leading vehicle, and the lock-up clutch control unit sets the specified oil temperature to a lower value the longer the width of the leading vehicle.

[0015] The tenth aspect of the present invention is the above-mentioned The first invention, the second invention, and The fourth invention Any one of In the vehicle control device described in the above, the lock-up clutch control unit sets a control end threshold used to determine the end of the oil temperature suppression control to a value lower than the specified oil temperature used to determine the start of the oil temperature suppression control, and terminates the oil temperature suppression control when it is determined that the temperature of the working oil is below the control end threshold during execution of the oil temperature suppression control.

[0016] The eleventh invention is the above Record number 3rd shot Clearly In the described vehicle control device, the follow-up driving control unit stops the follow-up driving when it determines that it is becoming difficult to perform the follow-up driving due to a change in driving performance caused by the oil temperature suppression control.

[0017] In addition, a twelfth aspect of the present invention is that, in the vehicle control device described in the eleventh aspect of the present invention, when the following driving control unit determines that it is becoming difficult to perform the following driving, it discontinues the following driving after receiving instructions or consent from the driver.

[0018] The thirteenth invention is the above Record number 3rd shot Clearly In the described vehicle control device, the lock-up clutch control unit prohibits the oil temperature suppression control when it detects a malfunction of any of the fluid transmission device including the lock-up clutch and the devices related to the control of the fluid transmission device.

[0019] The 14th invention is the above Record number 3rd shot ClearlyIn the vehicle control device described above, when the follow-up traveling ends while the oil temperature suppression control is being executed, the lock-up clutch control unit ends the oil temperature suppression control. Effect of the Invention

[0020] According to the first aspect of the present invention, during follow-up driving, in which the vehicle automatically drives at a predetermined distance from the preceding vehicle, oil temperature suppression control is executed to change the control state of the lock-up clutch so as to suppress a rise in temperature of the hydraulic oil circulating within the fluid transmission and used to switch the control state of the lock-up clutch, so that the amount of heat generated by the fluid transmission including the lock-up clutch can be reduced without changing the actual inter-vehicle distance to the predetermined inter-vehicle distance during follow-up driving. Therefore, the temperature rise of the hydraulic oil caused by a decrease in the cooling performance of the heat exchanger can be suppressed while maintaining the follow-up driving appropriately. Furthermore, according to the first invention, the easier it is for the hydraulic oil temperature to rise, the lower the specified oil temperature is set, and when it is determined that the hydraulic oil temperature is equal to or higher than the specified oil temperature, oil temperature suppression control is executed to reduce the amount of heat generated from the fluid transmission device. Therefore, when the hydraulic oil temperature is in a state where it is easy for it to rise, oil temperature suppression control is executed early, thereby suppressing the rise in the hydraulic oil temperature.

[0021] Furthermore, according to the second invention, the oil temperature suppression control is a control that switches the lockup clutch, which is controlled to a released state or a slip state based on a predetermined relationship, to an engaged state, so that the amount of heat generated from a fluid-type transmission device including the lockup clutch can be appropriately reduced.

[0022] According to the third aspect of the present invention, during follow-up driving, in which the vehicle automatically drives at a predetermined distance from the preceding vehicle, oil temperature suppression control is executed to change the control state of the lock-up clutch so as to suppress a rise in temperature of the hydraulic oil that circulates within the fluid transmission and is used to switch the control state of the lock-up clutch, so that the amount of heat generated by the fluid transmission including the lock-up clutch can be reduced without changing the actual inter-vehicle distance to the predetermined inter-vehicle distance during follow-up driving. Therefore, a rise in temperature of the hydraulic oil due to a decrease in the cooling performance of the heat exchanger can be suppressed while maintaining proper follow-up driving. Furthermore, according to the third invention, the oil temperature suppression control switches a lock-up clutch that is controlled to a released state based on a predetermined relationship to an engaged state, and switches a lock-up clutch that is controlled to a slip state based on a predetermined relationship to a released state, so that the amount of heat generated from a fluid-type transmission device including a lock-up clutch can be appropriately reduced.

[0023] Furthermore, according to the fourth invention, the easier it is for the hydraulic oil temperature to rise, the lower the specified oil temperature is set, and when it is determined that the hydraulic oil temperature is equal to or higher than the specified oil temperature, oil temperature suppression control is executed to reduce the amount of heat generated from the fluid transmission device. Therefore, when the hydraulic oil temperature is in a state where it is easy for it to rise, oil temperature suppression control is executed early, thereby suppressing the rise in the hydraulic oil temperature.

[0024] Furthermore, according to the fifth aspect of the invention, the ease with which the hydraulic oil temperature rises is varied depending on the environment of the driving route predicted for future driving, and the specified oil temperature is set based on environmental information for that driving route, so that oil temperature suppression control is executed early when the environment of the driving route makes it easy for the hydraulic oil temperature to rise.

[0025] Furthermore, according to the sixth aspect of the present invention, the vehicle load predicted for future travel is calculated based on environmental information about the travel route, and the greater the vehicle load, the lower the specified oil temperature is set to. Therefore, when the vehicle load is large and the temperature of the hydraulic oil is likely to rise, oil temperature suppression control is executed early.

[0026] Furthermore, according to the seventh aspect of the present invention, the ease with which the temperature of the hydraulic oil increases varies depending on the distance from the vehicle ahead, and the shorter the distance between the vehicles, the lower the specified oil temperature is set to. Therefore, when the air cooling performance is reduced due to the short distance between the vehicles, oil temperature suppression control is executed early.

[0027] Furthermore, according to the eighth aspect of the invention, the ease with which the temperature of the hydraulic oil increases varies depending on the projected area of ​​the leading vehicle, and the larger the projected area when viewed from behind the leading vehicle, the lower the specified oil temperature is set to. Therefore, when the projected area is large and the cooling performance by air is reduced, oil temperature suppression control is executed early.

[0028] Furthermore, according to the ninth aspect of the present invention, the ease with which the temperature of the hydraulic oil increases varies depending on the width of the preceding vehicle, and the greater the width of the preceding vehicle, the lower the specified oil temperature is set to. Therefore, when the width of the preceding vehicle is large and the cooling performance by the air is reduced, oil temperature suppression control is executed early.

[0029] Furthermore, according to the tenth aspect of the present invention, if it is determined that the temperature of the hydraulic oil during execution of the oil temperature suppression control is below a control termination threshold value which is set to a value lower than the specified oil temperature used to determine the start of the oil temperature suppression control, the oil temperature suppression control is terminated. This avoids hunting, in which the start and end of the oil temperature suppression control are repeated within a short period of time, and allows the oil temperature suppression control to be terminated only after the temperature rise of the hydraulic oil has been sufficiently suppressed.

[0030] In addition, according to the eleventh aspect of the present invention, if it is determined that it will be difficult to perform follow-up driving due to a change in driving performance caused by oil temperature suppression control, follow-up driving is stopped, thereby avoiding a rise in the temperature of the hydraulic oil due to follow-up driving.

[0031] In addition, according to the twelfth aspect of the present invention, when it is determined that it will be difficult to perform follow-up driving, follow-up driving is stopped after the driver gives instructions or consent, thereby enabling an appropriate transition from automatic follow-up driving to driving operated by the driver.

[0032] In addition, according to the 13th invention, when a failure is detected in any of the fluid transmission device including the lock-up clutch and the devices related to the control of the fluid transmission device, the oil temperature suppression control is prohibited, and therefore, when there is a risk that the control state of the lock-up clutch cannot be appropriately changed, the oil temperature suppression control is not executed.

[0033] According to the fourteenth aspect of the present invention, when follow-up traveling is ended while the oil temperature suppression control is being executed, the oil temperature suppression control is terminated, so that the oil temperature suppression control is not executed when follow-up traveling is not being executed, and the control of the entire vehicle is simplified. Also, when follow-up traveling is not being executed, no restrictions are imposed on the control state of the lock-up clutch in response to an increase in the temperature of the hydraulic oil. [Brief description of the drawings]

[0034] [Figure 1] 1 is a diagram illustrating a schematic configuration of a vehicle to which the present invention is applied, and is also a diagram illustrating main parts of control functions and a control system for various controls in the vehicle. [Diagram 2] FIG. 2 is a diagram illustrating a schematic configuration of a cooling system that cools oil. [Diagram 3] FIG. 4 is a diagram showing an example of a lock-up region diagram used for controlling a lock-up clutch. [Figure 4] FIG. 11 is a diagram showing an example of a predetermined relationship for setting an oil temperature threshold value based on a vehicle distance; [Diagram 5] FIG. 13 is a diagram showing an example of a predetermined relationship for setting an oil temperature threshold value based on the projected area of ​​a preceding vehicle. [Figure 6] FIG. 13 is a diagram showing an example of a predetermined relationship for setting an oil temperature threshold value based on a width of a preceding vehicle. [Figure 7] FIG. 13 is a diagram illustrating an example of a predetermined relationship for setting an oil temperature threshold value based on an expected load. [Figure 8] 1 is a flowchart illustrating the main control operations of the electronic control device, and is a flowchart illustrating the control operations for suppressing an increase in oil temperature caused by a decrease in the cooling performance of the heat exchanger while appropriately maintaining following driving. [Figure 9] This is a flowchart explaining the main parts of the control operation of the electronic control device, and is a flowchart explaining the control operation for suppressing an increase in oil temperature caused by a decrease in the cooling performance of the heat exchanger while appropriately maintaining following driving, and is an embodiment different from the flowchart of FIG. [Figure 10]10 is a diagram showing an example of a time chart when the control operation shown in the flowchart of FIG. 9 is executed. [Figure 11] This is a flowchart explaining the main parts of the control operation of the electronic control device, and is a flowchart explaining the control operation for suppressing an increase in oil temperature caused by a decrease in the cooling performance of the heat exchanger while appropriately maintaining following driving, and is an embodiment different from the flowchart of FIG. [Figure 12] This is a flowchart explaining the main parts of the control operation of the electronic control device, and is a flowchart explaining the control operation for suppressing an increase in oil temperature caused by a decrease in the cooling performance of the heat exchanger while appropriately maintaining following driving, and is an embodiment different from the flowchart of FIG. [Figure 13] This is a flowchart explaining the main parts of the control operation of the electronic control device, and is a flowchart explaining the control operation for suppressing an increase in oil temperature caused by a decrease in the cooling performance of the heat exchanger while appropriately maintaining following driving, and is an embodiment different from the flowchart of FIG. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0035] In an embodiment of the present invention, the vehicle capable of following the vehicle is any of various conventionally used vehicles, such as an engine-driven vehicle, an electric vehicle, or a hybrid electric vehicle equipped with an engine and a rotating machine as a power source. The engine is an internal combustion engine, such as a gasoline engine or a diesel engine. The rotating machine is, for example, a motor generator that can be selectively used as an electric motor or a generator. The motor generator functions as a power source when used as an electric motor, and can provide regenerative braking when used as a generator. The rotating machine may be, for example, an electric motor that does not function as a generator.

[0036] An automatic transmission may be provided in the power transmission path between the fluid-type power transmission device and the drive wheels. The automatic transmission may be, for example, a stepped transmission such as a planetary gear type or a synchronous meshing parallel two-shaft type, or a continuously variable transmission such as a belt type. The gear ratio in the automatic transmission is "rotation speed of an input rotating member / rotation speed of an output rotating member". The high-side gear ratio of the automatic transmission is a high-vehicle speed side gear ratio on the side where the gear ratio is small. The low-side gear ratio of the automatic transmission is a low-vehicle speed side gear ratio on the side where the gear ratio is large. For example, the lowest-side gear ratio is the lowest vehicle speed side gear ratio on the lowest vehicle speed side, and is the maximum gear ratio on which the gear ratio is the largest value.

[0037] When the vehicle is equipped with an automatic transmission, the hydraulic oil is a transmission oil used in the automatic transmission. For example, the hydraulic oil is an automatic transmission fluid (ATF) used in a stepped transmission such as a planetary gear type, or a CVTF used in a continuously variable transmission such as a belt type.

[0038] In addition, the following driving can be, for example, manned driving, in which a driver is on board, or unmanned driving, in which no driver is on board, using an automatic steering system or the like that can drive along a predetermined driving route.

[0039] The control device also calculates a required driving force for following the vehicle so that the vehicle distance between the vehicle itself and the preceding vehicle is maintained at a predetermined target vehicle distance as a predetermined vehicle distance, and controls the output of the power source so as to obtain the required driving force, thereby executing follow-up running control for following the vehicle at the target vehicle distance. It is preferable that the output control of the power source in the follow-up running control includes control of negative torque due to engine braking, regenerative control of the rotating machine, etc., and it is also possible to control braking force via an automatic brake system.

[0040] The vehicle capable of following may be a following vehicle in a platoon. The platooning is a traveling of the platoon participating vehicles, which includes, for example, a leading vehicle and following vehicles that automatically follow the leading vehicle in a single file at a predetermined distance from the leading vehicle, and which are connected and controlled via wireless communication.

[0041] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. EXAMPLES

[0042] Fig. 1 is a diagram for explaining the schematic configuration of a vehicle 10 to which the present invention is applied, and is also a diagram for explaining the main parts of the control functions and control system for various controls in the vehicle 10. In Fig. 1, the vehicle 10 is a hybrid vehicle equipped with an engine 12 and a rotary machine MG that function as a power source SP. The vehicle 10 also includes drive wheels 14 and a power transmission device 16 provided in a power transmission path between the engine 12 and the drive wheels 14.

[0043] The engine 12 is a known internal combustion engine such as a gasoline engine, a diesel engine, etc. An engine control device 50 including a throttle actuator, a fuel injection device, an ignition device, etc., provided in the vehicle 10 is controlled by an electronic control device 90 described later, whereby an engine torque Te, which is an output torque of the engine 12, is controlled.

[0044] The rotating machine MG is a rotating electric machine having a function as a motor 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 rotating machine MG is connected to a battery 54 provided in the vehicle 10 via an inverter 52 provided in the vehicle 10. The battery 54 is an electricity storage device that supplies and receives electric power to the rotating machine MG. The rotating machine MG controls the inverter 52 by an electronic control device 90 described later, thereby controlling the MG torque Tm, which is the output torque of the rotating machine MG. For example, when the rotating machine MG rotates in a forward direction, which is the same as the rotating direction when the engine 12 is in operation, the MG torque Tm is a power torque when it is a positive torque on the acceleration side, and is a regenerative torque when it is a negative torque on the deceleration side. The electric power is also the same as electric energy when there is no particular distinction. The motive power is also the same as driving force, torque, and force when there is no particular distinction.

[0045] The power transmission device 16 includes a torque converter 20, an automatic transmission 22, and the like, in a case 18 that is a non-rotating member attached to the vehicle body. The torque converter 20 is connected to the engine 12. The automatic transmission 22 is connected to the torque converter 20 and is interposed in a power transmission path between the torque converter 20 and the drive wheels 14. The power transmission device 16 also includes a propeller shaft 26 connected to a transmission output shaft 24 that is an output rotating member of the automatic transmission 22, a differential gear 28 connected to the propeller shaft 26, a pair of drive shafts 30 connected to the differential gear 28, and the like. The power transmission device 16 also includes a rotary machine connecting shaft 32 that connects the engine 12 and the torque converter 20, and the like.

[0046] The rotating machine MG is connected to the rotating machine connecting shaft 32 in the case 18 so as to be capable of transmitting power. That is, the rotating machine MG is connected to a power transmission path between the engine 12 and the driving wheels 14, particularly to a power transmission path between the engine 12 and the torque converter 20. In other words, the rotating machine MG is connected to the torque converter 20 and the automatic transmission 22 so as to be capable of transmitting power.

[0047] The torque converter 20 includes a pump wheel 20a connected to a rotary machine connecting shaft 32, and a turbine wheel 20b connected to a transmission input shaft 34, which is an input rotating member of the automatic transmission 22. The pump wheel 20a is an input member of the torque converter 20, and the turbine wheel 20b is an output member of the torque converter 20. The rotary machine connecting shaft 32 is also an input rotating member of the torque converter 20. The transmission input shaft 34 is also an output rotating member of the torque converter 20, which is formed integrally with a turbine shaft that is driven to rotate by the turbine wheel 20b. The torque converter 20 is a fluid-type power transmission device provided in a power transmission path between the power source SP and the driving wheels 14, which transmits power from the power source SP from the rotary machine connecting shaft 32 to the transmission input shaft 34 via a fluid. The fluid flowing through the torque converter 20 is also hydraulic oil used to switch the control state of the LU clutch 36, which will be described later. This hydraulic oil is also transmission oil used for the shifting operation of the automatic transmission 22. In this embodiment, this transmission oil is referred to as oil FLD.

[0048] The torque converter 20 includes an LU clutch 36 that connects the pump wheel 20a and the turbine wheel 20b, that is, that connects the rotating machine connecting shaft 32 and the transmission input shaft 34. The LU clutch 36 is a direct clutch that connects the input and output rotating members of the torque converter 20, that is, a known lock-up clutch.

[0049] The LU clutch 36 is a hydraulic friction engagement device constituted by, for example, a multi-plate or single-plate clutch. The LU clutch 36 has its operating state, i.e., its control state, changed by the LU torque Tlu, which is the torque capacity of the LU clutch 36, being changed by the LU oil pressure PRlu, which is a regulated oil pressure supplied from a hydraulic control circuit 56 provided in the vehicle 10.

[0050] The control states of the LU clutch 36 include a release state (also called a fully released state) in which the LU clutch 36 is released, a slip state in which the LU clutch 36 is engaged with slipping, and an engagement state (also called a fully engaged state) in which the LU clutch 36 is engaged. When the LU clutch 36 is in the release state, the torque converter 20 is in a torque converter state in which a torque amplification effect is obtained. When the LU clutch 36 is in the engaged state, i.e., in lock-up on, the torque converter 20 is in a lock-up state in which the pump wheel 20a and the turbine wheel 20b are rotated together.

[0051] The automatic transmission 22 is a known planetary gear type automatic transmission including, for example, one or more planetary gear devices (not shown) and an engagement device CB. The engagement device CB includes, for example, a plurality of known hydraulic friction engagement devices. The engagement devices CB have their respective torque capacities, or CB torques Tcb, changed by the CB hydraulic pressure PRcb, or regulated hydraulic pressure, supplied from the hydraulic control circuit 56, thereby switching between control states such as an engaged state, a slip state, and a disengaged state.

[0052] The automatic transmission 22 is a stepped transmission in which one of a plurality of gear stages (also called gear stages) with different speed ratios (also called gear ratios) γ (=AT input rotation speed Ni / AT output rotation speed No) is formed by engaging one of the engagement devices CB. The automatic transmission 22 switches between gear stages formed according to the accelerator operation of the driver (=operator) and the vehicle speed V by an electronic control device 90 described later. The AT input rotation speed Ni is the rotation speed of the transmission input shaft 34, and is the input rotation speed of the automatic transmission 22. The AT input rotation speed Ni is the same value as the turbine rotation speed Nt, which is the output rotation speed of the torque converter 20. The AT input rotation speed Ni can be expressed by the turbine rotation speed Nt. The AT output rotation speed No is the rotation speed of the transmission output shaft 24, and is the output rotation speed of the automatic transmission 22.

[0053] In the power transmission device 16, the power output from the power source SP is transmitted from the rotating machine connecting shaft 32 to the drive wheels 14 via the torque converter 20, the automatic transmission 22, the propeller shaft 26, the differential gear 28, and the drive shaft 30, in that order.

[0054] The vehicle 10 is equipped with the MOP 38, which is a mechanical oil pump. The MOP 38 is connected to the pump impeller 20a, and is rotationally driven by the power source SP to discharge hydraulic oil, i.e., oil FLD, used in the power transmission device 16. The oil FLD discharged by the MOP 38 is supplied to a hydraulic control circuit 56. The hydraulic control circuit 56 supplies the CB hydraulic pressure PRcb, the LU hydraulic pressure PRlu, and the like, each of which is adjusted based on the oil FLD discharged by the MOP 38.

[0055] The vehicle 10 is equipped with a wheel brake device 58. The wheel brake device 58 includes a brake master cylinder and a cylinder actuator (not shown) that generate brake hydraulic pressure. The wheels including the driving wheels 14 and the non-driving wheels (not shown) are each equipped with a wheel brake 59. If the vehicle 10 is an all-wheel drive vehicle, the non-driving wheels are driving wheels. The wheel brake device 58 is a brake device that applies wheel braking torque, which is a braking torque by the wheel brake 59, to the wheels according to a command from an electronic control device 90 (described later). The wheel brake device 58 supplies brake hydraulic pressure to wheel cylinders (not shown) provided in the wheel brakes 59 in response to, for example, the driver's depressing operation of the brake pedal. In the wheel brake device 58, a master cylinder hydraulic pressure corresponding to the brake operation amount Bra generated from the brake master cylinder is normally supplied to the wheel cylinder as brake hydraulic pressure. On the other hand, in the wheel braking device 58, for example, when the ABS function is activated, skid prevention control is activated, vehicle speed control is activated, automatic driving control is activated, the automatic brake function is activated, regenerative control is activated, etc., in order to generate wheel braking torque, brake hydraulic pressure of a magnitude corresponding to the wheel braking torque required for each control is supplied to the wheel cylinder. The brake operation amount Bra is a signal that corresponds to the brake pedal depression force and indicates the magnitude of the brake pedal depression operation by the driver, that is, the magnitude of the brake operation.

[0056] Fig. 2 is a diagram illustrating a schematic configuration of a cooling system 60 that cools the oil FLD and is mounted on the vehicle 10. In Fig. 2, the cooling system 60 includes, for example, a radiator 62, a water pump 64, and a heat exchanger 66. Note that the solid arrows in Fig. 2 indicate the flow of the cooling water CLT, and the dashed arrows indicate the flow of the oil FLD.

[0057] The radiator 62 receives the coolant CLT flowing out from the water jacket of the engine 12, cools the coolant CLT by heat exchange with outside air, and causes the cooled coolant CLT to flow out to a water pump 64. The water pump 64 is provided in, for example, the engine 12, and sucks in the coolant CLT flowing out from the radiator 62, a bypass flow passage 68 of the water jacket of the engine 12, and the heat exchanger 66, and supplies the coolant CLT to the water jacket of the engine 12, thereby circulating the coolant CLT to each part.

[0058] The heat exchanger 66 receives the cooling water CLT flowing out from the water jacket of the engine 12, circulates the cooling water CLT inside itself, and then flows it out to the water pump 64. The heat exchanger 66 also receives the oil FLD flowing out from the hydraulic control circuit 56, the torque converter 20, and the like, circulates the oil FLD inside itself, and then flows it out to the hydraulic control circuit 56. In this way, the heat exchanger 66 exchanges heat between the oil FLD and the cooling water CLT. In the heat exchanger 66, for example, when the engine is cold (during warm-up), heat is transferred from the cooling water CLT warmed by the engine 12 to the oil FLD, and the oil FLD is warmed up quickly. On the other hand, after warm-up, heat is transferred from the oil FLD warmed by the torque converter 20, etc. to the cooling water CLT, and the oil FLD is cooled. In this way, the heat exchanger 66 is an oil heat exchanger, for example, an oil cooler, that exchanges heat between the oil FLD and the cooling water CLT.

[0059] Returning to Fig. 1, the vehicle 10 further includes an electronic control device 90 including a control device for the vehicle 10. The electronic control device 90 includes a so-called microcomputer equipped with, for example, a CPU, RAM, ROM, an input / output interface, and the like, and the CPU executes various controls of the 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 includes computers for engine control, electric motor control, clutch control, transmission control, and the like as necessary.

[0060] The electronic control device 90 receives various signals based on detection values ​​from various sensors provided in the vehicle 10 (for example, an engine rotation speed sensor 70, a turbine rotation speed sensor 71, an output rotation speed sensor 72, a MG rotation speed sensor 73, an accelerator opening sensor 74, a throttle valve opening sensor 75, a brake sensor 76, a battery sensor 77, an oil temperature sensor 78, a shift position sensor 79, a vehicle surroundings information sensor 80, a navigation system 81, an auto-cruise setting device 82, etc.) (for example, an engine rotation speed Ne which is the rotation speed of the engine 12, a turbine rotation speed Nt which is the same value as the AT input rotation speed Ni, an AT output rotation speed No corresponding to the vehicle speed V, a MG rotation speed Nm which is the rotation speed of the rotating machine MG, a torque sensor 84 which indicates the magnitude of the driver's acceleration operation, etc.). The following information is supplied: accelerator opening θacc, which is the amount of accelerator operation by the driver; throttle valve opening θth, which is the opening of the electronic throttle valve; brake-on signal Bon, which is a signal indicating the state in which the brake pedal for activating wheel brakes 59 is being operated by the driver; brake operation amount Bra; battery temperature THbat, which is the temperature of battery 54; battery charge / discharge current Ibat, which is the charge / discharge current of battery 54; battery voltage Vbat, which is the voltage of battery 54; oil temperature THoil, which is the temperature of the oil FLD in the hydraulic control circuit 56; operating position (=operating position) POSop, which indicates the position to which the shift lever is operated; vehicle surroundings information Iard; navigation information Inavi; auto-cruise setting information Icru, etc.

[0061] The vehicle surroundings information sensor 80 includes at least one of, for example, a lidar, a radar, and an on-board camera, and directly acquires information about the road on which the vehicle is traveling and information about objects present around the vehicle. For example, the vehicle surroundings information sensor 80 detects objects in front of, on the sides of, and behind the vehicle 10, and outputs object information about the detected objects as vehicle surroundings information Iard. The object information includes the distance and direction of the detected object from the vehicle 10. The vehicle surroundings information Iard includes, for example, the inter-vehicle distance Dis to a vehicle ahead of the vehicle 10, i.e., a preceding vehicle, which is traveling just before the vehicle 10, the projected area Area of ​​the preceding vehicle as viewed from the rear, and the width of the preceding vehicle, i.e., the preceding vehicle width Wid, which is the vehicle dimension in a direction horizontally perpendicular to the traveling direction of the preceding vehicle.

[0062] The navigation system 81 is a known navigation system having a display, a speaker, and the like. The navigation system 81 locates the vehicle position on pre-stored map data based on position information based on, for example, GPS signals (trajectory signals) transmitted by GPS (Global Positioning System) satellites. When a destination is input, the navigation system 81 calculates a driving route from a departure point to the destination, and instructs the driver on the driving route and the like via a display, a speaker, and the like. The navigation information Inavi includes map information such as road information and facility information based on map data pre-stored in the navigation system 81. The navigation information Inavi also includes weather information and traffic information acquired, for example, by communication or the like.

[0063] The auto-cruise setting device 82 is a device for selecting auto-cruise driving, which performs constant speed driving and following driving, as an automatic driving that automatically controls the power source SP so that the vehicle 10 travels in a predetermined target driving state without the need for acceleration / deceleration operation by the driver. That is, the vehicle 10 is capable of auto-cruise driving, which automatically controls the power source SP according to the target vehicle speed Vt, etc., in addition to manual driving, in which the power source SP is controlled according to the driver's acceleration / deceleration operation using the accelerator pedal, etc. The auto-cruise setting device 82 is a device that not only selects auto-cruise driving, but also sets the target vehicle speed Vt, increases / decreases the target vehicle speed Vt, and sets the target inter-vehicle distance Dt during following driving in which the vehicle travels following a preceding vehicle, and is disposed, for example, on a steering wheel, etc., and the target vehicle speed Vt, the target inter-vehicle distance Dt, etc. are input by the driver as auto-cruise setting information Icru.

[0064] The electronic control device 90 outputs various command signals (e.g., an engine control command signal Se for controlling the engine 12, an MG control command signal Sm for controlling the rotating machine MG, a CB hydraulic control command signal Sbc for controlling the engagement device CB, an LU hydraulic control command signal Slu for controlling the LU clutch 36, a brake control command signal Sbra for controlling the wheel braking torque, etc.) to each device (e.g., the engine control device 50, the inverter 52, the hydraulic control circuit 56, the wheel brake device 58, etc.) provided in the vehicle 10.

[0065] In order to realize various controls in the vehicle 10, the electronic control unit 90 functionally comprises a power source control means, i.e., a power source control unit 92, a transmission control means, i.e., a transmission control unit 94, an LU clutch control means, i.e., an LU clutch control unit 96, and a following driving control means, i.e., a following driving control unit 98.

[0066] The power source control unit 92 is a hybrid control means, i.e., a hybrid control unit, which operates the engine 12 and the rotary machine MG in cooperation to execute hybrid drive control and the like. The power source control unit 92 calculates a 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 drive demand amount map is a relationship that is experimentally or design-wise obtained and stored in advance, i.e., a predetermined relationship. The drive demand amount is a demand value for the drive amount output by the vehicle 10. The drive amount is, for example, a drive force Fr or a drive torque Tr at the drive wheels 14, and the drive demand amount is, for example, a required drive force Frdem or a required drive torque Trdem at the drive wheels 14. The power source control unit 92 outputs an engine control command signal Se for controlling the engine 12 and outputs an MG control command signal Sm for controlling the rotary machine MG so that the torque of the power source SP required to realize, for example, the required drive torque Trdem is obtained, taking into account a transmission loss, an auxiliary load, a gear ratio γ of the automatic transmission 22, and the like.

[0067] The power transmission device 16 may include, for example, an engine disconnection clutch that interrupts the power transmission between the engine 12 and the rotary machine MG in the power transmission path between the engine 12 and the drive wheels 14. When the engine disconnection clutch is included, the power source control unit 92 can perform motor running, that is, BEV (Battery Electric Vehicle) running, in which the vehicle runs using only the rotary machine MG as the power source SP, when the clutch is released and the engine 12 is stopped. For example, when the required drive torque Trdem can be satisfied only by the output of the rotary machine MG, the power source control unit 92 establishes the BEV drive mode as the drive mode. The BEV drive mode is an electric drive mode that allows BEV running (=electric running). On the other hand, when the required drive torque Trdem cannot be satisfied without using at least the output of the engine 12, the power source control unit 92 establishes the engine drive mode, that is, the HEV drive mode as the drive mode. The HEV drive mode is a hybrid drive mode that allows engine running, i.e., hybrid running (=HEV running), in which at least the engine 12 is used as the power source SP when the engine connection / disconnection clutch is in an engaged state. On the other hand, even if the required drive torque Trdem can be satisfied only by the output of the rotary machine MG, the power source control unit 92 establishes the HEV drive mode as the drive mode when the battery 54 needs to be charged or when the engine 12 or the like needs to be warmed up.

[0068] The transmission control unit 94 uses a shift map, which is a predetermined relationship, for example, to determine whether to shift the automatic transmission 22, and outputs a CB hydraulic control command signal Sbc to the hydraulic control circuit 56 to execute shift control of the automatic transmission 22 as necessary, that is, according to the result of the shift determination. The shift map is a predetermined relationship having a shift line for determining whether to shift the automatic transmission 22, on a two-dimensional coordinate system having the vehicle speed V and the required driving torque Trdem as variables, for example. In the shift map, the AT output rotation speed No may be used instead of the vehicle speed V, and the required driving force Frdem, the accelerator opening θacc, the throttle valve opening θth, etc. may be used instead of the required driving torque Trdem.

[0069] The LU clutch control unit 96 is a lock-up clutch control means, or a lock-up clutch control unit, that controls the LU clutch 36 to be in one of the control states of the released state, the slip state, and the engaged state, that is, that controls the control state of the LU clutch 36. Specifically, the LU clutch control unit 96 determines the control region using, for example, a lock-up region diagram, which is a predetermined relationship, and outputs an LU hydraulic pressure control command signal Slu to the hydraulic control circuit 56 to supply the LU clutch 36 with the LU hydraulic pressure PRlu that realizes the control state corresponding to the determined control region.

[0070] Fig. 3 is a diagram showing an example of a lock-up region diagram used for controlling the LU clutch 36. In Fig. 3, the lock-up region diagram has a predetermined relationship on a two-dimensional coordinate system with vehicle speed V and accelerator opening θacc as variables, which has a release region corresponding to the release state, a slip region corresponding to the slip state, and a lock-up region corresponding to the engagement state. In the lock-up region diagram of Fig. 3, the AT output rotation speed No or the like may be used instead of the vehicle speed V, and the required drive torque Trdem or the like may be used instead of the accelerator opening θacc.

[0071] When the LU clutch control unit 96 determines that the control region is the lock-up region, it executes lock-up control of the LU clutch 36, by setting the LU hydraulic pressure PRlu to obtain the LU torque Tlu capable of transmitting the input torque to the LU clutch 36, i.e., the LU input torque Tinlu, and bringing the LU clutch 36 into a fully engaged state. The LU input torque Tinlu is, for example, the torque of the power source SP. The LU torque Tlu capable of transmitting the LU input torque Tinlu is, for example, a torque value obtained by multiplying the LU input torque Tinlu by a safety factor (>1).

[0072] When the LU torque Tlu is small relative to the LU input torque Tinlu, slippage occurs in the LU clutch 36. When the LU clutch control unit 96 determines that the control region is the slip region, it performs slip control of the LU clutch 36, i.e., LU slip control, by setting the LU hydraulic pressure PRlu for realizing the slip amount of the LU clutch 36, i.e., the target value of the LU slip amount Nslplut, for the LU input torque Tinlu, and putting the LU clutch 36 in a target slip state. The target slip state of the LU clutch 36 is a target slip state in which the target LU slip amount Nslplut is realized. In other words, the LU clutch control unit 96 performs LU slip control by setting the LU clutch command pressure Splu that realizes the target LU slip amount Nslplut and controlling the LU clutch 36 to be in a slip state. The LU slip amount Nslplu is the rotational speed difference (=Ne-Nt) between the LU input rotational speed (=engine rotational speed Ne) and the LU output rotational speed (=turbine rotational speed Nt). In the lockup region diagram of Fig. 3, the slip region is set, for example, in a lower vehicle speed region compared to the lockup region, and is a region in which it is difficult to execute lockup control and a slip state is set to improve energy efficiency and drivability. The slip region is also a region that is set in consideration of drivability and muffled noise (for example, NV (noise and vibration) performance).

[0073] The following running control unit 98 executes following running as an automatic driving. Following running is an autonomous running without requiring the driver to perform an acceleration / deceleration operation, and executes following running control to follow the vehicle while maintaining the target inter-vehicle distance Dt set by the auto-cruise setting device 82. In the following running control, the following running control unit 98 controls following running to automatically run the vehicle while keeping a target inter-vehicle distance Dt as a predetermined inter-vehicle distance from the preceding vehicle. That is, in the following running control, the following running control unit 98 follows the preceding vehicle while maintaining the target inter-vehicle distance Dt. In the following running control, the following running control unit 98 calculates a required driving torque Trdem required for following running in a state in which the inter-vehicle distance Dis is the target inter-vehicle distance Dt, and controls the torque of the power source SP so that the required driving torque Trdem is obtained. The target inter-vehicle distance Dt is variably set according to, for example, the vehicle speed V. The required driving torque Trdem here is obtained by feedback control, feedforward control, or the like, based on, for example, the difference between the target inter-vehicle distance Dt and the actual inter-vehicle distance Dis. Furthermore, when the required driving torque Trdem is negative, such as when the preceding vehicle is decelerating, the following running control unit 98 generates engine braking or regenerative braking by the rotary machine MG, and, if necessary, obtains the negative required driving torque Trdem by combining it with the braking force of the wheel brakes 59 controlled by the wheel brake device 58. Note that even during this following running, the transmission control unit 94 executes shift control to switch the gear of the automatic transmission 22 in accordance with shift conditions such as a shift map.

[0074] In the above-mentioned following running, the preceding vehicle acts as a windbreak, and the air flow rate hitting the vehicle 10 is reduced. Therefore, while the running resistance of the vehicle 10 is reduced, the cooling performance of the radiator 62 in the cooling system 60 is reduced, and the cooling performance of the heat exchanger 66 is reduced. This makes it easier for the oil temperature THoil to rise, and there is a risk that the oil temperature THoil will become too high and cause deterioration of the oil FLD. When the oil temperature THoil becomes high during following running, it is desirable to suppress the rise in the oil temperature THoil without stopping following running or lengthening the inter-vehicle distance Dis without maintaining the target inter-vehicle distance Dt.

[0075] Therefore, while the follow-up travel control unit 98 is performing follow-up travel, the LU clutch control unit 96 executes oil temperature suppression control CTtho, which changes the control state of the LU clutch 36 so as to suppress an increase in the oil temperature THoil.

[0076] Among the control states of the LU clutch 36, the engaged state in which the LU slip amount Nslplu is zero generates the least amount of heat from the torque converter 20. Therefore, when the LU clutch 36 is controlled to a released state or a slip state while following travel is being performed, the LU clutch control unit 96 switches the LU clutch 36 to an engaged state. When the LU clutch control unit 96 controls the LU clutch 36 to an engaged state while following travel is being performed, the LU clutch control unit 96 maintains the engaged state. In other words, the oil temperature suppression control CTtho is a control that maintains the LU clutch 36, which is controlled to an engaged state based on the lock-up region diagram (see FIG. 3), in the engaged state as it is, and also is a control that switches the LU clutch 36, which is controlled to a released state or a slip state based on the lock-up region diagram, to an engaged state, i.e., lock-up on.

[0077] Specifically, the follow-up running control unit 98 determines whether follow-up running is being performed. If the follow-up running control unit 98 determines that follow-up running is not being performed, the LU clutch control unit 96 does not execute the oil temperature suppression control CTtho. Therefore, if follow-up running by the follow-up running control unit 98 ends while the oil temperature suppression control CTtho is being performed and the follow-up running control unit 98 determines that follow-up running is not being performed, the LU clutch control unit 96 ends the oil temperature suppression control CTtho and does not execute the oil temperature suppression control CTtho.

[0078] When the following running control unit 98 determines that following running is being performed, the LU clutch control unit 96 sets an oil temperature threshold value THf as a predetermined oil temperature that is a threshold value for determining whether or not to perform the oil temperature suppression control CTtho. Then, the LU clutch control unit 96 determines whether the oil temperature THoil is equal to or higher than the oil temperature threshold value THf.

[0079] When the LU clutch control unit 96 determines that the oil temperature THoil is equal to or higher than the oil temperature threshold value THf, it executes the oil temperature suppression control CTtho to reduce the amount of heat generated from the torque converter 20. On the other hand, when the LU clutch control unit 96 determines that the oil temperature THoil is less than the oil temperature threshold value THf, it does not execute the oil temperature suppression control CTtho. Moreover, when the LU clutch control unit 96 determines that the oil temperature THoil is less than the oil temperature threshold value THf while the oil temperature suppression control CTtho is being executed, it ends the oil temperature suppression control CTtho and does not execute the oil temperature suppression control CTtho.

[0080] If the vehicle is in a state in which the oil temperature THoil is likely to rise, it is better to execute the oil temperature suppression control CTtho early. The LU clutch control unit 96 sets a lower oil temperature threshold value THf the more likely the oil temperature THoil is to rise.

[0081] The longer the inter-vehicle distance Dis from the preceding vehicle, the more the air flow rate hitting the vehicle 10 increases, improving the cooling performance of the cooling system 60 by air, and making it difficult for the oil temperature THoil to rise. In other words, the shorter the inter-vehicle distance Dis, the less the air flow rate hitting the vehicle 10 decreases, lowering the cooling performance of the cooling system 60, making it easier for the oil temperature THoil to rise. In this way, the ease with which the oil temperature THoil rises varies depending on the inter-vehicle distance Dis from the preceding vehicle. For this reason, the LU clutch control unit 96 sets the oil temperature threshold THf to a lower value as the inter-vehicle distance Dis becomes shorter, for example, as shown in FIG. 4. FIG. 4 is a diagram showing an example of a predetermined relationship for setting the oil temperature threshold THf based on the inter-vehicle distance Dis, for example.

[0082] The larger the projected area Area of ​​the preceding vehicle, the smaller the air flow rate hitting the vehicle 10, which reduces the cooling performance of the cooling system 60 and makes it easier for the oil temperature THoil to rise. In this way, the ease with which the oil temperature THoil rises varies depending on the projected area Area of ​​the preceding vehicle. For this reason, the LU clutch control unit 96 sets the oil temperature threshold THf to a lower value as the projected area Area of ​​the preceding vehicle increases, as shown in FIG. 5, for example. FIG. 5 is a diagram showing an example of a predetermined relationship for setting the oil temperature threshold THf based on the projected area Area of ​​the preceding vehicle, for example.

[0083] The longer the preceding vehicle width Wid, the smaller the flow rate of air hitting the vehicle 10, which reduces the cooling performance of the cooling system 60 and makes it easier for the oil temperature THoil to rise. In this way, the ease with which the oil temperature THoil rises varies depending on the preceding vehicle width Wid. For this reason, the LU clutch control unit 96 sets the oil temperature threshold THf to a lower value as the preceding vehicle width Wid increases, as shown in FIG. 6, for example. FIG. 6 is a diagram showing an example of a predetermined relationship for setting the oil temperature threshold THf based on the preceding vehicle width Wid, for example.

[0084] When the environment of the predicted driving route, which is the driving route that the vehicle 10 is expected to travel in the future, differs, the ease with which the oil temperature THoil rises differs. For example, when the environment of the predicted driving route is a driving route with many uphill roads, the predicted load Loadex, which is the vehicle load Load expected for the future driving, is likely to be increased. The larger the predicted load Loadex, the more the required driving torque Tr is increased, so that the LU clutch 36 is released more frequently so that the torque converter 20 is in a torque converter state in which a torque amplification effect is obtained. When the frequency of the LU clutch 36 being released increases, the oil temperature THoil is likely to rise. In this way, the ease with which the oil temperature THoil rises varies depending on the predicted load Loadex. Therefore, the LU clutch control unit 96 acquires road information in the navigation information Inavi as environmental information of the predicted driving route, and calculates the predicted load Loadex based on the road information of the predicted driving route. Then, as shown in FIG. 7, for example, the LU clutch control unit 96 sets the oil temperature threshold value THf to a lower value as the predicted load Loadex increases. FIG. 7 is a diagram showing an example of a predetermined relationship for setting the oil temperature threshold value THf based on, for example, the expected load Loadex.

[0085] Alternatively, for example, if the outside air temperature is high along the predicted driving route, the oil temperature THoil is likely to rise. The LU clutch control unit 96 acquires weather information in the navigation information Inavi as environmental information along the predicted driving route, and sets the oil temperature threshold value THf to a lower value as the outside air temperature along the predicted driving route increases.

[0086] Alternatively, for example, if there is traffic congestion on the predicted driving route, the oil temperature THoil is likely to rise. The LU clutch control unit 96 acquires traffic information in the navigation information Inavi as environmental information on the predicted driving route, and sets the oil temperature threshold value THf to a lower value as the degree of traffic congestion on the predicted driving route increases.

[0087] In this way, the tendency for the oil temperature THoil to increase varies depending on the environment of the predicted travel route. The LU clutch control unit 96 sets the oil temperature threshold value THf based on environmental information about the predicted travel route.

[0088] When the following driving control unit 98 determines that following driving is being performed, the LU clutch control unit 96 acquires, as vehicle surroundings information Iard, the inter-vehicle distance Dis to the preceding vehicle, the projected area Area of ​​the preceding vehicle, the width Wid of the preceding vehicle, etc. In addition, when the following driving control unit 98 determines that following driving is being performed, the LU clutch control unit 96 acquires a predicted driving route of the vehicle 10 based on the navigation information Inavi, and acquires environmental information of the predicted driving route.

[0089] The LU clutch control unit 96 sets the oil temperature threshold THf based on the vehicle surroundings information Iard and environmental information of the predicted driving route. For example, the LU clutch control unit 96 sets the lowest oil temperature threshold THf among the oil temperature thresholds THf calculated based on the vehicle surroundings information Iard and the environmental information of the predicted driving route as the oil temperature threshold THf used to determine whether or not to execute the oil temperature suppression control CTtho.

[0090] In the oil temperature suppression control CTtho, for example, if the LU clutch 36, which is controlled to a released state based on the lockup region diagram, is switched to lockup on, the torque converter 20 will no longer be able to amplify torque. This will make it difficult for the follow-up running control unit 98 to achieve the required drive torque Trdem required for follow-up running, and there is a risk that follow-up running will not be able to be continued appropriately. The follow-up running control unit 98 determines whether or not it will become difficult to perform follow-up running due to a change in running performance caused by the oil temperature suppression control CTtho. If the follow-up running control unit 98 determines that it will become difficult to perform follow-up running, it stops follow-up running and ends follow-up running.

[0091] FIG. 8 is a flowchart illustrating the main control operations of the electronic control device 90, which are for suppressing an increase in the oil temperature THoil due to a decrease in the cooling performance of the heat exchanger 66 while maintaining proper following driving, and which is executed, for example, repeatedly.

[0092] In FIG. 8, first, in step S10 (hereinafter, step will be omitted) corresponding to the function of the following driving control unit 98, it is determined whether or not following driving is being performed. If the determination in S10 is positive, in S20 corresponding to the function of the LU clutch control unit 96, the vehicle distance Dis to the preceding vehicle, the projected area Area of ​​the preceding vehicle, the preceding vehicle width Wid, and the like are acquired as the vehicle surroundings information Iard. Next, in S30 corresponding to the function of the LU clutch control unit 96, road information, weather information, traffic information, and the like are acquired as the environmental information of the predicted driving route. Next, in S40 corresponding to the function of the LU clutch control unit 96, the oil temperature threshold THf is set based on the vehicle surroundings information Iard and the environmental information of the predicted driving route. Next, in S50 corresponding to the function of the LU clutch control unit 96, it is determined whether or not the oil temperature THoil is equal to or higher than the oil temperature threshold THf. If the determination in S50 is positive, in S60 corresponding to the function of the LU clutch control unit 96, it is determined whether or not the control state of the LU clutch 36 is in the released state. If the determination in S60 is negative, then in S70, which corresponds to the function of the LU clutch control unit 96, it is determined whether the control state of the LU clutch 36 is in a slip state. If the determination in S70 is negative, then this routine is terminated. If the determination in S60 is positive, or if the determination in S70 is positive, then in S80, which corresponds to the function of the LU clutch control unit 96, the control state of the LU clutch 36 is switched to lock-up on. Then, in S90, which corresponds to the function of the following running control unit 98, it is determined whether or not it becomes difficult to perform following running, in particular whether or not it is impossible to perform following running. If the determination in S90 is negative, then this routine is terminated. If the determination in S90 is positive, then in S100, which corresponds to the function of the following running control unit 98, following running is terminated. If the determination in S10 is negative, or if the determination in S50 is negative, then in S110, which corresponds to the function of the LU clutch control unit 96, the oil temperature suppression control CTtho is not executed.

[0093] As described above, according to this embodiment, while following running is being performed, the oil temperature suppression control CTtho is executed to change the control state of the LU clutch 36 so as to suppress an increase in the oil temperature THoil, so that it is possible to reduce the amount of heat generated from the torque converter 20 including the LU clutch 36 without changing the actual following distance Dis relative to the target following distance Dt during following running. Therefore, it is possible to suppress an increase in the oil temperature THoil caused by a decrease in the cooling performance of the heat exchanger 66 while appropriately maintaining following running.

[0094] Furthermore, according to this embodiment, the oil temperature suppression control CTtho is a control that switches the LU clutch 36, which is controlled to a released state or a slip state based on the lock-up region diagram, to an engaged state, so that the amount of heat generated from the torque converter 20 can be appropriately reduced.

[0095] Furthermore, according to this embodiment, the easier it is for the oil temperature THoil to rise, the lower the oil temperature threshold value THf is set, and when it is determined that the oil temperature THoil is equal to or higher than the oil temperature threshold value THf, the oil temperature suppression control CTtho is executed to reduce the amount of heat generated from the torque converter 20. Therefore, when the oil temperature THoil is in a state where it is easy for it to rise, the oil temperature suppression control CTtho is executed early, and the rise in the oil temperature THoil is suppressed.

[0096] Furthermore, according to this embodiment, the tendency for the oil temperature THoil to rise varies depending on the environment of the predicted driving route, and the oil temperature threshold value THf is set based on environmental information about the predicted driving route. Therefore, when the environment of the predicted driving route makes it easy for the oil temperature THoil to rise, the oil temperature suppression control CTtho is executed early.

[0097] Furthermore, according to this embodiment, the predicted load Loadex is calculated based on environmental information about the predicted driving route, and the larger the predicted load Loadex, the lower the oil temperature threshold value THf is set to. Therefore, when the predicted load Loadex is large and the oil temperature THoil is likely to rise, the oil temperature suppression control CTtho is executed early.

[0098] Furthermore, according to this embodiment, the tendency for the oil temperature THoil to rise varies depending on the vehicle distance Dis from the preceding vehicle. The shorter the vehicle distance Dis, the lower the oil temperature threshold value THf is set to. Therefore, when the vehicle distance Dis is short and the cooling performance by the air is reduced, the oil temperature suppression control CTtho is executed early.

[0099] Furthermore, according to this embodiment, the ease with which the oil temperature THoil rises varies depending on the projected area Area of ​​the preceding vehicle, and the larger the projected area Area of ​​the preceding vehicle, the lower the oil temperature threshold value THf is set to. Therefore, when the projected area Area is large and the cooling performance by air is reduced, the oil temperature suppression control CTtho is executed early.

[0100] Furthermore, according to this embodiment, the ease with which the oil temperature THoil rises varies depending on the preceding vehicle width Wid. The longer the preceding vehicle width Wid, the lower the oil temperature threshold value THf is set to. Therefore, when the preceding vehicle width Wid is long and the air cooling performance is reduced, the oil temperature suppression control CTtho is executed early.

[0101] Furthermore, according to this embodiment, if it is determined that it will be difficult to perform follow-up driving due to a change in driving performance caused by the oil temperature suppression control CTtho, follow-up driving is stopped, thereby preventing an increase in the oil temperature THoil due to follow-up driving.

[0102] Furthermore, according to this embodiment, if follow-up traveling ends while the oil temperature suppression control CTtho is being executed, the oil temperature suppression control CTtho is terminated, and therefore the oil temperature suppression control CTtho is not executed when follow-up traveling is not being executed, simplifying the control of the entire vehicle 10. Furthermore, when follow-up traveling is not being executed, no restrictions are imposed on the control state of the LU clutch 36 in response to an increase in the oil temperature THoil.

[0103] Next, another embodiment of the present invention will be described. In the following description, parts common to the embodiments are given the same reference numerals and the description thereof will be omitted. EXAMPLES

[0104] In the first embodiment described above, the same oil temperature threshold value THf is used for determining the start and end of the oil temperature suppression control CTtho. In this embodiment, different oil temperature threshold values ​​THf are used for determining the start and end of the oil temperature suppression control CTtho.

[0105] The LU clutch control unit 96 sets the control end threshold THfoff used to determine the end of the oil temperature suppression control CTtho to a value lower than the control start threshold THfon used to determine the start of the oil temperature suppression control CTtho. The LU clutch control unit 96 sets, as the control start threshold THfon, for example, the oil temperature threshold THf set in the above-mentioned first embodiment. In addition, the LU clutch control unit 96 sets, as the control end threshold THfoff, for example, a value lower than the control start threshold THfon by a predetermined hunting suppression value.

[0106] When the following running control unit 98 determines that following running is being performed, the LU clutch control unit 96 sets a control start threshold THfon and a control end threshold THfoff. Then, the LU clutch control unit 96 determines whether the oil temperature THoil is equal to or higher than the control start threshold THfon. When the LU clutch control unit 96 determines that the oil temperature THoil is equal to or higher than the control start threshold THfon, it executes the oil temperature suppression control CTtho. In addition, the LU clutch control unit 96 determines whether the oil temperature THoil is equal to or lower than the control end threshold THfoff while the oil temperature suppression control CTtho is being performed. When the LU clutch control unit 96 determines that the oil temperature THoil is equal to or lower than the control end threshold THfoff, it ends the oil temperature suppression control CTtho.

[0107] FIG. 9 is a flowchart for explaining the main part of the control operation of the electronic control device 90, and is a flowchart for explaining the control operation for suppressing an increase in the oil temperature THoil caused by a decrease in the cooling performance of the heat exchanger 66 while maintaining appropriate following driving, and is executed repeatedly, for example. FIG. 9 is an embodiment different from the flowchart of FIG. 8. In FIG. 9, the points different from FIG. 8 are mainly described. FIG. 10 is a diagram showing an example of a time chart when the control operation shown in the flowchart of FIG. 9 is executed.

[0108] In FIG. 9, instead of S40, in S40B corresponding to the function of the LU clutch control unit 96, the control start threshold THfon and the control end threshold THfoff are set. Next, instead of S50, in S50B corresponding to the function of the LU clutch control unit 96, it is determined whether the oil temperature THoil is equal to or higher than the control start threshold THfon. If the determination in S50B is negative, it is determined whether the oil temperature suppression control CTtho is being executed in S55 corresponding to the function of the LU clutch control unit 96. If the determination in S55 is positive, it is determined whether the oil temperature THoil is equal to or lower than the control end threshold THfoff in S58 corresponding to the function of the LU clutch control unit 96. If the determination in S55 is negative or if the determination in S58 is positive, the S110 is executed. If the determination in S50B is positive or if the determination in S58 is negative, the S60 is executed.

[0109] FIG. 10 shows an example of a change in the oil temperature THoil when the following running is being performed. In FIG. 10, time t1 indicates the time when the oil temperature THoil becomes equal to or higher than the control start threshold THfon during the following running. Accordingly, the oil temperature suppression control CTtho is turned on, that is, executed, and the control state of the LU clutch 36 is switched from the released state to the lock-up on state (see time t1-t2). When the oil temperature THoil is lowered by the execution of the oil temperature suppression control CTtho and the oil temperature THoil becomes equal to or lower than the control end threshold THfoff, the oil temperature suppression control CTtho is turned off, that is, terminated, and the control state of the LU clutch 36 is switched to the released state (see time t2 and after). In FIG. 10, the control state of the LU clutch 36 is switched to the released state with the end of the oil temperature suppression control CTtho, but after the end of the oil temperature suppression control CTtho, the control state of the LU clutch 36 may be returned to the normal control controlled based on the lock-up region diagram (see FIG. 3), and is not necessarily set to the released state.

[0110] As described above, according to this embodiment, if it is determined that the oil temperature THoil is equal to or lower than the control end threshold THfoff, which is set to a value lower than the control start threshold THfon, during execution of the oil temperature suppression control CTtho, the oil temperature suppression control CTtho is terminated. This avoids hunting, in which the oil temperature suppression control CTtho is started and ended repeatedly within a short period of time, and the oil temperature suppression control CTtho is terminated only after the rise in the oil temperature THoil has been sufficiently suppressed. EXAMPLES

[0111] In the above-described first embodiment, the oil temperature suppression control CTtho is a control for switching the LU clutch 36, which is controlled to be in a released state or a slip state based on the lock-up region diagram (see FIG. 3), to an engaged state. The amount of heat generated by the torque converter 20 is greatest in a slip state, and there are cases in which there is little difference between the released state and the engaged state. In such a case, the LU clutch 36, which is controlled to be in a slip state, may be placed in a released state in which torque amplification is achieved in the torque converter 20.

[0112] In this embodiment, when the LU clutch 36 is controlled to a slip state while following travel is being performed, the LU clutch control unit 96 switches the LU clutch 36 to a released state. In other words, the oil temperature suppression control CTtho is a control that switches the LU clutch 36, which is controlled to a released state based on the lock-up region diagram, to an engaged state, and also switches the LU clutch 36, which is controlled to a slip state based on the lock-up region diagram, to a released state.

[0113] Fig. 11 is a flowchart for explaining the main part of the control operation of the electronic control device 90, and is a flowchart for explaining the control operation for suppressing the rise in the oil temperature THoil caused by the deterioration of the cooling performance of the heat exchanger 66 while maintaining the following running appropriately, and is executed repeatedly, for example. Fig. 11 is an embodiment different from the flowchart of Fig. 8. Fig. 11 mainly describes the points different from Fig. 8.

[0114] In Fig. 11, if the determination in S60 is negative, S70 is executed. If the determination in S70 is positive, the control state of the LU clutch 36 is switched to the released state in S75, which corresponds to the function of the LU clutch control unit 96. If the determination in S60 is positive, S80 is executed. Following S75 or S80, S90 is executed.

[0115] As described above, according to this embodiment, the oil temperature suppression control CTtho switches the LU clutch 36, which is controlled to a released state based on the lock-up region diagram, to an engaged state, and also switches the LU clutch 36, which is controlled to a slip state based on the lock-up region diagram, to a released state, so that the amount of heat generated by the torque converter 20 can be appropriately reduced. EXAMPLES

[0116] In the above-described embodiment 1, when it is determined that it is difficult to execute the following driving, the following driving is stopped. At this time, since the stopping of the following driving requires the driver to perform operations such as acceleration and deceleration, in order to smoothly transition to the driver's operation, the driver may be asked to confirm that the following driving is to be stopped.

[0117] When the following driving control unit 98 determines that it will be difficult to perform following driving, it stops following driving after receiving an instruction or consent from the driver, and ends following driving. For example, when the following driving control unit 98 determines that it will be difficult to perform following driving, it notifies the driver that following driving cannot be continued by displaying on an in-vehicle monitor or the like. The following driving control unit 98 determines whether the driver has instructed or consented to the end of following driving, for example, based on the driver's operation on an in-vehicle monitor or the like. When the following driving control unit 98 determines that the driver has instructed or consented to the end of following driving, it stops following driving and ends following driving.

[0118] Fig. 12 is a flowchart for explaining the main part of the control operation of the electronic control device 90, and is a flowchart for explaining the control operation for suppressing the rise in the oil temperature THoil caused by the deterioration of the cooling performance of the heat exchanger 66 while maintaining the following running appropriately, and is executed repeatedly, for example. Fig. 12 is an embodiment different from the flowchart of Fig. 8. Fig. 12 mainly describes the points different from Fig. 8.

[0119] In Fig. 12, if the determination in S90 is positive, then in S95, which corresponds to the function of the following driving control unit 98, the driver is notified that following driving cannot be performed. Next, in S98, which corresponds to the function of the following driving control unit 98, it is determined whether the driver has instructed or agreed to end following driving. If the determination in S98 is negative, then S98 is repeatedly executed. If the determination in S98 is positive, then S100 is executed.

[0120] As described above, according to this embodiment, when it is determined that it will be difficult to execute follow-up driving, follow-up driving is stopped after the driver gives instructions or consent, so that an appropriate transition can be made from automatic follow-up driving to driving operated by the driver. EXAMPLES

[0121] If the torque converter 20 including the LU clutch 36 or devices related to the control of the torque converter 20 fail, the LU clutch 36 may not be properly controlled, and the oil temperature suppression control CTtho may not be properly controlled. Devices related to the control of the torque converter 20 include, for example, the hydraulic control circuit 56 and the electronic control device 90.

[0122] The LU clutch control unit 96 prohibits the oil temperature suppression control CTtho when it detects a failure in the torque converter 20 or any of the devices related to the control of the torque converter 20. In addition, the LU clutch control unit 96 may put the LU clutch 36 in a released state when it detects a failure in the torque converter 20 or any of the devices related to the control of the torque converter 20.

[0123] Fig. 13 is a flowchart for explaining the main part of the control operation of the electronic control device 90, and is a flowchart for explaining the control operation for suppressing the rise in the oil temperature THoil caused by the deterioration of the cooling performance of the heat exchanger 66 while maintaining the following running appropriately, and is executed repeatedly, for example. Fig. 13 is an embodiment different from the flowchart of Fig. 8. Fig. 13 mainly describes the points different from Fig. 8.

[0124] 13, in S5 corresponding to the function of the LU clutch control unit 96, it is determined whether or not a failure has been detected in the torque converter 20 or any of the devices related to the control of the torque converter 20. If the determination in S5 is positive, then in S8 corresponding to the function of the LU clutch control unit 96, the oil temperature suppression control CTtho is prohibited and the LU clutch 36 is put into a released state. If the determination in S5 is negative, the above-mentioned S10 is executed.

[0125] As described above, according to this embodiment, if a failure is detected in the torque converter 20 or any of the devices related to the control of the torque converter 20, the oil temperature suppression control CTtho is prohibited, and therefore, when there is a risk that the control state of the LU clutch 36 cannot be appropriately changed, the oil temperature suppression control CTtho is not executed.

[0126] Although the embodiment of the present invention has been described in detail above with reference to the drawings, the present invention can be applied to other embodiments.

[0127] For example, in the above-described embodiments 2 to 5, two or more of the embodiments may be combined and implemented with respect to the above-described embodiment 1.

[0128] In the above embodiment, the oil temperature threshold THf does not necessarily have to be set based on the vehicle surroundings information Iard or the environmental information of the predicted driving route, and a value that can suppress the oil temperature THoil from becoming high may be determined in advance. The oil temperature threshold THf may also be set based on one piece of information from the vehicle surroundings information Iard or one piece of information from the environmental information of the predicted driving route.

[0129] In the above-described embodiment, the flowchart in FIG. 8 may be modified as appropriate, for example, S90 and S100 in the flowchart in FIG. 8 may not be provided.

[0130] In the above-described embodiment, the heat exchanger 66 may be, for example, an oil cooler with a built-in radiator that is directly exposed to air.

[0131] It should be noted that the above is merely one embodiment, and the present invention can be embodied in various modified and improved forms based on the knowledge of those skilled in the art. [Explanation of symbols]

[0132] 10: Vehicle 12: Engine (power source) 14: Drive wheel 20: Torque converter (fluid transmission device) 36: LU clutch (lock-up clutch) 90: Electronic control device (control device) 96: LU clutch control unit (lock-up clutch control unit) 98: Following driving control unit FLD: Oil (hydraulic oil) MG: Rotating machine (power source) SP: Power source

Claims

1. A control device for a vehicle including a power source and a hydrodynamic power transmission device having a lock-up clutch provided in a power transmission path between the power source and a drive wheel, comprising: a following driving control unit that controls following driving in which the vehicle automatically drives at a predetermined distance from a preceding vehicle; a lock-up clutch control unit that controls the lock-up clutch so that the lock-up clutch is in one of a released state, a slip state, and an engaged state; Contains The lock-up clutch control unit executes an oil temperature suppression control for changing a control state of the lock-up clutch so as to suppress a temperature rise of hydraulic oil that circulates through the fluid transmission device and is used to switch the control state of the lock-up clutch during the execution of the following running, A vehicle control device characterized in that the lock-up clutch control unit sets a lower predetermined oil temperature the more easily the temperature of the hydraulic oil increases, and when it determines that the temperature of the hydraulic oil is equal to or higher than the predetermined oil temperature, it executes the oil temperature suppression control to reduce the amount of heat generated from the fluid transmission device.

2. 2. The vehicle control device according to claim 1, wherein the oil temperature suppression control is a control for switching the lock-up clutch, which is controlled to the released state or the slip state based on a predetermined relationship, to the engaged state.

3. A control device for a vehicle including a power source and a fluid-type transmission device having a lock-up clutch provided in a power transmission path between the power source and a drive wheel, comprising: a following driving control unit that controls following driving in which the vehicle automatically drives at a predetermined distance from a preceding vehicle; a lock-up clutch control unit that controls the lock-up clutch so that the lock-up clutch is in one of a released state, a slip state, and an engaged state; Contains The lock-up clutch control unit executes an oil temperature suppression control for changing a control state of the lock-up clutch so as to suppress a temperature rise of hydraulic oil that circulates through the fluid transmission device and is used to switch the control state of the lock-up clutch during the execution of the following running, A vehicle control device characterized in that the oil temperature suppression control is control to switch the lock-up clutch, which is controlled to the released state based on a predetermined relationship, to the engaged state, and to switch the lock-up clutch, which is controlled to the slip state based on the relationship, to the released state.

4. The vehicle control device according to claim 3, characterized in that the lock-up clutch control unit sets a lower predetermined oil temperature the more easily the temperature of the hydraulic oil increases, and when it determines that the temperature of the hydraulic oil is equal to or higher than the predetermined oil temperature, it executes the oil temperature suppression control so as to reduce the amount of heat generated from the fluid transmission device.

5. The ease with which the temperature of the hydraulic oil increases varies depending on the environment of the route expected in the future.

5. The vehicle control device according to claim 1, wherein the lock-up clutch control unit sets the predetermined oil temperature based on environmental information of the travel route.

6. 6. The vehicle control device according to claim 5, wherein the lock-up clutch control unit calculates a vehicle load predicted for future travel based on environmental information about the travel route, and sets the specified oil temperature to a lower value as the vehicle load increases.

7. The ease with which the temperature of the hydraulic oil increases varies depending on a vehicle-to-vehicle distance from the preceding vehicle, 5. The vehicle control device according to claim 1, wherein the lock-up clutch control unit sets the predetermined oil temperature to a lower value as the inter-vehicle distance becomes shorter.

8. the ease with which the temperature of the hydraulic oil increases is varied depending on a projected area of ​​the preceding vehicle, 5. The vehicle control device according to claim 1, wherein the lock-up clutch control unit sets the predetermined oil temperature to a lower value as a projected area of ​​the preceding vehicle when viewed from behind is larger.

9. the ease with which the temperature of the hydraulic oil increases varies depending on a width of the preceding vehicle, which is a vehicle dimension in a direction horizontally perpendicular to a traveling direction of the preceding vehicle, 5. The vehicle control device according to claim 1, wherein the lock-up clutch control unit sets the predetermined oil temperature to a lower value as the width of the preceding vehicle becomes larger.

10. A vehicle control device as described in any one of claims 1, 2, and 4, characterized in that the lock-up clutch control unit sets a control end threshold used to determine the end of the oil temperature suppression control to a value lower than the specified oil temperature used to determine the start of the oil temperature suppression control, and terminates the oil temperature suppression control when it determines that the temperature of the hydraulic oil is below the control end threshold during execution of the oil temperature suppression control.

11. 4. The vehicle control device according to claim 3, wherein the following-travel control unit stops the following-travel control when it determines that execution of the following-travel control has become difficult due to a change in driving performance caused by the oil temperature suppression control.

12. 12. The vehicle control device according to claim 11, wherein the following-travel control unit, when it determines that it is becoming difficult to perform the following-traveling, stops the following-traveling after receiving an instruction or consent from the driver.

13. 4. The vehicle control device according to claim 3, wherein the lock-up clutch control unit prohibits the oil temperature suppression control when it detects a malfunction of the fluid transmission device including the lock-up clutch and any of the devices related to the control of the fluid transmission device.

14. The vehicle control device according to claim 3, wherein the lock-up clutch control unit terminates the oil temperature suppression control when the follow-up running ends while the oil temperature suppression control is being executed.

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