Vehicle control device

Abstract

To suppress excessive increase in an oil temperature in an automatic transmission due to reduction in cooling performance caused by reduction in airflow volume resulting from presence of a preceding vehicle during follow-up traveling.SOLUTION: During execution of follow-up traveling control, a high-oil-temperature determination value THs is variably set on the basis of information (an inter-vehicle distance Dis and a projected area Apr) on a preceding vehicle affecting airflow volume. Meanwhile, an oil temperature THoil in a transmission part is detected, and when it is equal to or higher than the high-oil-temperature determination value THs, a high-oil-temperature-time shift map M2 is selected, so that a high-speed-side gear stage is frequently used. As a result, rotational speeds of respective parts of the transmission part (automatic transmission), including an input rotational speed, are reduced, and heat generation caused by the stirring of oil is suppressed, so that increase in the oil temperature THoil due to reduction in cooling performance caused by reduction in the airflow volume during follow-up traveling is suppressed. In other words, it is possible to enjoy a fuel-economy improvement effect because the preceding vehicle acts as a windshield during the follow-up traveling, thereby reducing traveling resistance, and to suppress excessive increase in the oil temperature THoil caused by the reduction in the airflow volume.SELECTED DRAWING: Figure 6

Description

[Technical field]

[0001] The present invention relates to a vehicle control device, and more particularly to a vehicle control device capable of following a preceding vehicle at a predetermined target inter-vehicle distance. [Background technology]

[0002] There is known a vehicle control device having a following driving control unit that controls the output of a driving force source so that the vehicle follows the preceding vehicle at a predetermined target distance without the driver needing to accelerate or decelerate. The device described in Patent Document 1 is one example of such a device, and since the preceding vehicle acts as a windscreen to reduce running resistance, it also reduces the amount of ventilation airflow for the cooling system such as the radiator, thereby degrading cooling performance, so a technology has been proposed to adjust the distance between the vehicles so as to obtain a predetermined amount of ventilation airflow. [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] Incidentally, even in vehicles with an automatic transmission capable of changing the gear ratio, the oil temperature of the automatic transmission may rise excessively due to a reduction in the amount of ventilation air caused by the presence of a leading vehicle when following another vehicle, and it is therefore conceivable to adjust the distance between vehicles to obtain a predetermined cooling performance by applying the technology described in Patent Document 1. However, there is a possibility that adjusting the distance between vehicles may increase running resistance and deteriorate fuel efficiency, leaving room for improvement.

[0005] The present invention has been made against the background of the above circumstances, and its purpose is to prevent the oil temperature in an automatic transmission from rising excessively when cooling performance is reduced due to a decrease in ventilation air volume caused by the presence of a leading vehicle during following driving. [Means for solving the problem]

[0006] In order to achieve this object, the first invention relates to a vehicle control device having (a) a driving force source and an automatic transmission capable of changing the gear ratio, (b) a follow-up driving control unit that controls the output of the driving force source so that the vehicle follows a preceding vehicle at a predetermined target distance without the need for acceleration or deceleration by the driver, and (c) a gear change control unit that changes the gear ratio of the automatic transmission in accordance with predetermined gear change conditions, wherein (d) while the follow-up driving control unit is performing follow-up driving control, the gear change control unit variably sets a high oil temperature judgment value based on information about the preceding vehicle that affects the ventilation air volume, while detecting the oil temperature of the automatic transmission, and when the oil temperature is equal to or higher than the high oil temperature judgment value, changes the gear change conditions based on the oil temperature so that a higher gear ratio having a smaller gear ratio is used more frequently than when the oil temperature is lower than the high oil temperature judgment value. The present invention can also be implemented by detecting other temperatures that change in response to the oil temperature, such as the temperature of the automatic transmission itself. The gear ratio is the ratio of the input rotation speed to the output rotation speed of the automatic transmission (=input rotation speed / output rotation speed), and the smaller the gear ratio, the lower the input rotation speed.

[0007] A second invention is characterized in that, in the vehicle control device of the first invention, (a) the information regarding the preceding vehicle is the inter-vehicle distance from the vehicle to the preceding vehicle, and (b) the gear shift control unit variably sets the high oil temperature judgment value depending on the inter-vehicle distance so that the high oil temperature judgment value is lower when the inter-vehicle distance is small compared to when the inter-vehicle distance is large.

[0008] A third invention is characterized in that, in the vehicle control device of the first invention, (a) the information relating to the preceding vehicle is a width dimension of the rear of the preceding vehicle, and (b) the gear shift control unit variably sets the high oil temperature judgment value in accordance with the width dimension so that the high oil temperature judgment value is lower when the width dimension is large compared to when the width dimension is small.

[0009] A fourth invention is characterized in that, in the vehicle control device of the first invention, (a) the information about the preceding vehicle is a projected area as seen from the rear side of the preceding vehicle, and (b) the gear shift control unit variably sets the high oil temperature judgment value depending on the projected area so that the high oil temperature judgment value is lower when the projected area is large compared to when the projected area is small.

[0010] A fifth invention is characterized in that, in the vehicle control device of the first invention, the shift control unit variably sets the high oil temperature judgment value based on the expected load, which is the predicted future driving load of the vehicle, in addition to information about the preceding vehicle, so that the high oil temperature judgment value is lower when the expected load is large compared to when the expected load is small.

[0011] A sixth aspect of the present invention is the vehicle control device according to the fifth aspect of the present invention, characterized in that the expected load is determined based on a predetermined travel route.

[0012] A seventh invention is characterized in that, in the vehicle control device of the first invention, when the shift conditions are changed by the gear change control unit during execution of the following running control so that the higher speed gear ratio is used more frequently, the following running control unit determines whether or not it is appropriate to continue the following running control, and limits the following running control if it determines that it is inappropriate to continue.

[0013] An eighth invention is a control device for a vehicle of the first invention, wherein the shift control unit switches from a normal shifting condition to a high oil temperature shifting condition in which the high speed side gear ratio is used frequently when the oil temperature is equal to or higher than the high oil temperature judgment value, and returns from the high oil temperature shifting condition to the normal shifting condition on the condition that the oil temperature becomes equal to or lower than a return judgment value which is lower than the high oil temperature judgment value. Effect of the Invention

[0014] In such a vehicle control device, during execution of the following running control, the high oil temperature judgment value is variably set based on information about the preceding vehicle that affects the ventilation air volume, while the oil temperature of the automatic transmission is detected, and when the oil temperature is equal to or higher than the high oil temperature judgment value, the gear shift conditions are changed so that the high speed side gear ratio is used more frequently than when the oil temperature is lower than the high oil temperature judgment value. When the high speed side gear ratio is used more frequently in this manner, the rotation speed of each part of the automatic transmission, including the input rotation speed, is reduced, and heat generation due to stirring of the oil is suppressed, so that the oil temperature rise due to the decrease in cooling performance caused by the decrease in the ventilation air volume during following running is suppressed. In particular, since the high oil temperature judgment value for determining whether or not to change the gear shift conditions is variably set based on information about the preceding vehicle that affects the ventilation air volume, the oil temperature rise due to the decrease in the ventilation air volume during following running can be appropriately suppressed. As a result, it is possible to suppress an excessive rise in the oil temperature due to the decrease in the ventilation air volume while enjoying the effect of improving fuel efficiency by reducing the running resistance due to the preceding vehicle acting as a windshield during following running.

[0015] In the second invention, the distance to the preceding vehicle is used as information about the preceding vehicle that affects the ventilation air volume, and the high oil temperature judgment value is variably set according to the distance between the vehicles so that the high oil temperature judgment value is lower when the distance between the vehicles is small compared to when the distance between the vehicles is large, so that the rise in oil temperature is appropriately suppressed. In other words, when the distance between the vehicles is small, the deterioration of cooling performance due to the reduction in the ventilation air volume caused by the preceding vehicle becomes significant, so by lowering the high oil temperature judgment value and making the high speed gear ratio more frequently used from a lower oil temperature, the rise in oil temperature can be appropriately suppressed regardless of the deterioration of cooling performance.

[0016] In the third invention, the width dimension of the rear of the preceding vehicle is used as information about the preceding vehicle that affects the ventilation air volume, and the high oil temperature judgment value is variably set according to the width dimension so that the high oil temperature judgment value is lower when the width dimension is large compared to when the width dimension is small, so that the rise in oil temperature is appropriately suppressed. In other words, when the width dimension of the preceding vehicle is large, the decrease in cooling performance due to the decrease in ventilation air volume caused by the preceding vehicle becomes significant, so by lowering the high oil temperature judgment value and making the high speed side gear ratio frequently used from a lower oil temperature, the rise in oil temperature can be appropriately suppressed regardless of the decrease in cooling performance.

[0017] In the fourth invention, the projected area of ​​the preceding vehicle as seen from the rear side is used as information about the preceding vehicle that affects the ventilation air volume, and the high oil temperature judgment value is variably set according to the projected area so that the high oil temperature judgment value is lower when the projected area is large compared to when the projected area is small, so that the rise in oil temperature is appropriately suppressed. In other words, when the projected area of ​​the preceding vehicle is large, the deterioration of cooling performance due to the reduction in ventilation air volume caused by the preceding vehicle becomes significant, so by lowering the high oil temperature judgment value and making the high speed gear ratio more frequently used from a lower oil temperature, the rise in oil temperature can be appropriately suppressed regardless of the deterioration of cooling performance.

[0018] In the fifth aspect of the invention, the high oil temperature determination value is variably set based on the predicted load in addition to information about the preceding vehicle that affects the ventilation air volume so that the high oil temperature determination value is lower when the predicted load is large compared to when it is small, so that the rise in oil temperature is more appropriately suppressed. In other words, when the predicted load is large, the low-speed gear ratio with a large gear ratio is used frequently, and the oil temperature is likely to rise, so by lowering the high oil temperature determination value and making the high-speed gear ratio used frequently from a lower oil temperature, the rise in oil temperature caused by a large running load can be appropriately suppressed.

[0019] In the sixth aspect of the present invention, the above-mentioned expected load is calculated based on a predetermined driving route. Therefore, by appropriately predicting the expected load and lowering the high oil temperature judgment value, the rise in oil temperature can be appropriately suppressed.

[0020] In the seventh aspect of the invention, when the shift conditions are changed by the shift control unit while follow-up cruise control is being executed, a determination is made as to whether or not it is appropriate to continue the follow-up cruise control, and if it is determined that continuation is inappropriate, the follow-up cruise control is restricted. This prevents the driver from feeling uncomfortable due to large changes in the distance between the vehicle and the preceding vehicle or large changes in the torque of the driving force source caused by the continuation of unreasonable follow-up cruise control.

[0021] The eighth invention is a case in which normal shifting conditions and high oil temperature shifting conditions, in which higher speed gear ratios are frequently used, are switched between based on the oil temperature. When the oil temperature reaches or exceeds a high oil temperature judgment value, the shifting conditions are switched to the high oil temperature shifting conditions. On the other hand, the shifting conditions are returned to the normal shifting conditions from the high oil temperature shifting conditions when the oil temperature falls below a return judgment value that is lower than the high oil temperature judgment value. This prevents the shifting conditions from being frequently switched due to slight fluctuations in the oil temperature. [Brief description of the drawings]

[0022] [Figure 1] FIG. 1 is a diagram illustrating an example of a hybrid electric vehicle equipped with an on-board control device as a control device that is one embodiment of the present invention, and shows a schematic diagram of the drive system, as well as control functions for various controls and key parts of the control system. [Diagram 2] FIG. 2 is a schematic diagram for explaining a specific example of the HEV transmission device of FIG. 1. [Diagram 3] 3 is an engagement operation table showing the relationship between a plurality of gear stages of a transmission part provided in the HEV transmission device of FIG. 2 and the engagement / disengagement states of engagement devices for establishing those gear stages. [Figure 4] 3 is a diagram illustrating an example of a normal-time shift map M1 used in shift control of the shifting section of FIG. 2 by a shift control section that is functionally provided in the on-board control device of FIG. 1. FIG. [Diagram 5] FIG. 5 is a diagram illustrating an example of a high oil temperature shift map M2 that is used in place of the normal time shift map M1 of FIG. 4 when the oil temperature is high. [Figure 6] 6 is a flowchart illustrating an operation of a gear shift control unit functionally provided in the on-board control device of FIG. 1 when selecting which of the gear shift maps of FIG. 4 and FIG. 5 is to be used when performing gear shift control. [Figure 7] 1 is a flowchart illustrating the operation of an auto-cruise control unit that is functionally equipped in the on-board control device of FIG. 1 when terminating follow-up cruise control under certain conditions when shift control is performed using high oil temperature shift map M2. [Figure 8] FIG. 7 is a diagram for explaining a high oil temperature determination standard value THsst that is determined according to the inter-vehicle distance Dis when setting the high oil temperature determination value THs in step S6 of FIG. 6. [Figure 9] 7 is a diagram for explaining a correction coefficient Ka determined according to a projection area Apr when setting a high oil temperature determination value THs in step S6 of FIG. 6. FIG. [Figure 10] FIG. 7 is a diagram for explaining a correction coefficient Kl determined according to an expected load Lex when setting a high oil temperature determination value THs in step S6 of FIG. 6. [Figure 11] FIG. 7 is a diagram for explaining a correction coefficient Kw determined according to the width dimension Wpr when the high oil temperature determination value THs is set in consideration of the width dimension Wpr in step S6 of FIG. 6. [Figure 12] 7 is an example of a time chart showing a change in oil temperature THoil when shift control is performed by changing between a normal time shift map M1 and a high oil temperature time shift map M2 in accordance with the flowchart of FIG. 6. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0023] The present invention is preferably applied to a case where a plurality of freight vehicles or buses, etc., are driven in a convoy over a relatively long distance on a highway or a motorway, but may also be applied to a case where a general vehicle, such as a passenger car, is driven in a convoy on a highway or a general road without being driven in a convoy. The present invention can be applied to various conventional vehicles, such as engine-driven vehicles, electric vehicles, or hybrid electric vehicles equipped with an engine and a rotary machine as a driving force source. It is preferable that a driver is on board the vehicle, but the present invention can also be applied to an unmanned vehicle equipped with an automatic steering system or the like that can drive the vehicle along a predetermined driving route. The present invention is preferably applied to an automatic transmission, such as a stepped transmission in which the gear stages are changed according to the engagement and disengagement states of a plurality of friction engagement devices, such as a planetary gear type or a two-shaft meshing type, but may also be applied to a vehicle equipped with a continuously variable transmission, such as a belt type, that continuously changes the gear ratio.

[0024] The following running control unit calculates a driving demand amount required for following the preceding vehicle so that the distance between the preceding vehicle and the preceding vehicle is maintained at a predetermined target distance, and controls the output of the driving force source so as to obtain the driving demand amount, thereby executing following running control for following the preceding vehicle at the target distance. In addition to the following running control, the following running control may be capable of executing autonomous running control for running at a predetermined target vehicle speed by calculating a driving demand amount required for running at a predetermined target vehicle speed and controlling the output of the driving force source so as to obtain the driving demand amount. The autonomous running control may be a constant speed running control for running at a constant target vehicle speed, or an autonomous running control for automatically running while changing the vehicle speed according to a target vehicle speed that is successively variably set according to the running route. The output control of the driving force source in the following running control and the autonomous running control is preferably controlled including negative torque by engine braking, regenerative control of a rotary machine, etc., and braking force control may also be performed via an automatic brake system.

[0025] The shift control unit is configured to change to a high oil temperature shift condition that is determined so that a higher speed gear ratio such as a higher gear is used more frequently than usual when the oil temperature becomes equal to or higher than a predetermined high oil temperature judgment value. For example, two types of shift conditions, normal and high oil temperature, may be determined in advance, or the normal shift condition may be simply corrected to shift to the lower vehicle speed side. In addition, it is possible to change the shift condition in two stages, whether or not the oil temperature is equal to or higher than the high oil temperature judgment value, and to change the shift condition continuously or in multiple stages of three or more stages according to the oil temperature. The high oil temperature judgment value is variably set based on information about the preceding vehicle that affects the ventilation air volume. The information about the preceding vehicle that affects the ventilation air volume may be, for example, the distance between the preceding vehicle, the width dimension of the rear of the preceding vehicle, the projected area as seen from the rear side, etc., and the high oil temperature judgment value may be variably set based on any one of the information, but may also be variably set using multiple information. In addition to the information about the preceding vehicle that affects the ventilation air volume, the high oil temperature judgment value may be variably set in consideration of other factors that affect the oil temperature, such as an expected load. In addition to changing the shift conditions, it is also possible to suppress the rise in oil temperature by using other controls in combination, such as adjusting the vehicle distance as described in Patent Document 1. EXAMPLES

[0026] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Note that in the following embodiments, the drawings are appropriately simplified or modified for the purpose of explanation, and the shapes, dimensional ratios, angles, etc. of the various parts are not necessarily drawn accurately.

[0027] FIG. 1 is a diagram for explaining an example of a vehicle 10 equipped with an on-board control device 130 as a control device according to an embodiment of the present invention, and is a diagram showing a schematic diagram of a drive system and a main part of the control system for various controls. The vehicle 10 is a freight vehicle or the like used for platooning, and is a hybrid electric vehicle with a front-mounted engine and rear-wheel drive (FR) system, and is equipped with an engine 32 and a transmission device 34 for a hybrid electric vehicle (HEV) connected to the engine 32. A propeller shaft 46 is connected to the transmission device 34 for the HEV, and left and right rear wheels 52 are rotated and driven via a differential gear 48 and left and right drive shafts 50. The engine 32 is an internal combustion engine such as a gasoline engine or a diesel engine, and is used as a driving force source for traveling. The engine 32 controls an engine torque Te, which is an output torque of the engine 32, by controlling an engine control device (not shown) having a throttle actuator, a fuel injection device, an ignition device, etc., by the on-board control device 130.

[0028] FIG. 2 is a schematic diagram for explaining a specific example of the HEV transmission device 34. In FIG. 2, the HEV transmission device 34 includes a rotating machine MG arranged in a transmission case 60 (hereinafter, referred to as the case 60) as a non-rotating member attached to the vehicle body, and a speed change unit 64 connected to the rotating machine MG and the engine 32 via a torque converter 62. The rotating machine MG, the torque converter 62, and the speed change unit 64 are configured substantially symmetrically with respect to a center line, and the lower half of the center line is omitted in the schematic diagram of FIG. 2. The rotating machine MG is a motor generator having a function as an electric motor that generates mechanical power from electric power and a function as a generator that generates electric power from mechanical power, and is, for example, a three-phase AC synchronous motor. The rotating machine MG has an MG torque Tmg, which is the torque of the rotating machine MG, and an MG rotation speed Nmg, which is the rotation speed of the rotating machine MG, controlled by the on-board control device 130. The rotating machine MG is used as a driving force source, and generates driving force for traveling instead of or in addition to the engine 32. The rotating machine MG is also controlled to function as a generator to generate electricity when rotated by the power of the engine 32 or the driven force input from the rear wheels 52, and applies regenerative braking to the rear wheels 52. The rotating machine MG is connected to the crankshaft of the engine 32 directly or via a damper or the like (not shown). An engine disconnecting clutch or the like that connects and disconnects power transmission may be provided between the rotating machine MG and the engine 32.

[0029] The torque converter 62 includes a pump wheel 62a connected to the rotary machine MG via an MG connecting shaft 66, and a turbine wheel 62b connected to an input shaft 68 of the transmission unit 64. The torque converter 62 includes an LU (lock-up) clutch 70 that connects the pump wheel 62a and the turbine wheel 62b. The LU clutch 70 changes the LU clutch torque Tlu, which is the torque capacity of the LU clutch 70, by controlling the LU oil pressure PRlu by the on-board control device 130, and switches the operating state, i.e., the control state. The operating states of the LU clutch 70 include a release state in which the LU clutch 70 is released, a slip state in which the LU clutch 70 is engaged with slipping, and a lock-up state in which the LU clutch 70 is fully engaged. The release state of the LU clutch 70 results in a torque converter state in which the torque converter 62 provides a torque amplification effect. Furthermore, by placing the LU clutch 70 in a lock-up state, the torque converter 62 is placed in a directly connected state in which the pump wheel 62a and the turbine wheel 62b are rotated integrally.

[0030] The transmission unit 64 changes the input rotation speed Ni, which is the rotation speed of the input shaft 68, in stages and transmits it to the output shaft 72, from which the power is transmitted to the propeller shaft 46. The transmission unit 64 is equipped with a first planetary gear set 74 and a second planetary gear set 76, both of which are single pinion types, and is a planetary gear-type stepped automatic transmission in which a plurality of gears with different gear ratios γ [=input rotation speed Ni / rotation speed (output rotation speed) No of the output shaft 72] are mechanically established. The input rotation speed Ni is equal to the turbine rotation speed Nt, which is the output rotation speed of the torque converter 62, and the output rotation speed No corresponds to the vehicle speed V. The first planetary gear set 74 includes three rotation elements: a first sun gear S1, a first carrier CA1 supporting the first pinion gear P1 so that it can rotate and revolve around its axis, and a first ring gear R1 meshing with the first sun gear S1 via the first pinion gear P1. The second planetary gear set 76 includes three rotation elements: a second sun gear S2, a second carrier CA2 supporting the second pinion gear P2 so that it can rotate and revolve around its axis, and a second ring gear R2 meshing with the second sun gear S2 via the second pinion gear P2.

[0031] In the first planetary gear set 74 and the second planetary gear set 76, the first sun gear S1 is selectively connected to the case 60 via the first brake B1. The first carrier CA1 is integrally connected to the second ring gear R2, and the first carrier CA1 and the second ring gear R2 are selectively connected to the input shaft 68 via the second clutch C2 and selectively connected to the case 60 via the second brake B2. The first carrier CA1 and the second ring gear R2 are also connected to the case 60, which is a non-rotating member, via the one-way clutch F1, and are allowed to rotate in the same direction as the engine 32 and are prohibited from rotating in the opposite direction. The first ring gear R1 is integrally connected to the second carrier CA2, and the first ring gear R1 and the second carrier CA2 are connected to the output shaft 72. The second sun gear S2 is selectively connected to the input shaft 68 via the first clutch C1. The first clutch C1, the second clutch C2, the first brake B1, and the second brake B2 (hereinafter, referred to as the engagement device CB unless otherwise specified) are hydraulic friction engagement devices that are engaged by a hydraulic actuator, and four forward gears from a first gear "1st" to a fourth gear "4th" are established as multiple gear stages by engaging each clutch C and brake B according to the engagement operation table shown in FIG. 3. In addition, by disengaging all of the engagement devices CB, neutral "N" is established in which power transmission is interrupted. The parenthetical "(○)" in FIG. 3 indicates engagement when engine braking is applied. In other words, the shifting unit 64 is a stepped transmission in which multiple forward gear stages are established according to the engagement and disengagement states of the multiple engagement devices CB.

[0032] Returning to Fig. 1, the vehicle 10 is equipped with an on-board control device 130 as a control device that executes various types of control. The on-board control device 130 is an electronic control device that includes a so-called microcomputer equipped with, for example, a CPU, RAM, ROM, an input / output interface, etc., and the CPU executes various types of control of the 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 on-board control device 130 is configured to include multiple electronic control devices for engine control, MG control, hydraulic control, etc., as necessary.

[0033] The on-board control device 130 receives various signals based on detection values ​​from various sensors provided in the vehicle 10 (for example, an engine rotation speed sensor 90, a turbine rotation speed sensor 92, an output rotation speed sensor 94, a MG rotation speed sensor 96, an accelerator opening sensor 98, a throttle valve opening sensor 100, a road surface gradient sensor 102, an oil temperature sensor 104, a vehicle front photographing camera 106, a vehicle distance sensor 108 such as a millimeter wave radar, an auto-cruise setting device 110, a lever position sensor 120, etc.), and outputs various signals (for example, an engine rotation speed Ne which is the rotation speed of the engine 32, a turbine rotation speed Nt which is the same value as the input rotation speed Ni, an output rotation speed No corresponding to the vehicle speed V, an MG rotation speed Nmg which is the rotation speed of the rotating machine MG, an accelerator opening θacc which is an operation amount of an accelerator operation member such as an accelerator pedal and which represents an output request amount of the driver, a throttle valve opening θth which is an opening amount of the electronic throttle valve, a road surface gradient Φ, an oil temperature THoil of the transmission unit 64, and the like). , a video image Vfr of the area in front of the vehicle, a distance Dis to the preceding vehicle 56, auto-cruise setting information Acrui, a signal indicating the operating position POSsh of the shift lever 122, etc. are supplied. The oil temperature THoil is the temperature of the lubricating oil that lubricates the transmission unit 64.

[0034] The shift lever 122 is disposed near the driver's seat, and is a shift operation member operated by the driver to switch the shift range, which is the power transmission state of the transmission unit 64, and has a plurality of operation positions POSsh. As the operation positions POSsh, a plurality of positions, for example, P, R, N, and D, are provided. The P position is an operation position for selecting a P (parking) range for parking, in which the transmission unit 64 is in a neutral state in which power transmission is interrupted and the rotation of the output shaft 72 is mechanically prevented. The neutral state is, for example, a state in which all the engagement devices CB of the transmission unit 64 are released. The R position is an operation position for selecting an R (reverse) range for reverse driving. The N position is an operation position for selecting an N (neutral) range in which the transmission unit 64 is in a neutral state similar to the P position. The D position is an operating position that selects the D (drive) range for forward driving, in which the transmission 64 automatically switches between multiple forward gears "1st" to "4th" in accordance with predetermined shift conditions using driving conditions such as vehicle speed V and required drive torque Trdem as variables.

[0035] The auto-cruise setting device 110 is a device for selecting auto-cruise driving, which performs constant speed driving and following driving, as an automatic driving that automatically controls the engine 32 and the rotary machine MG, which are the driving force sources, so that the vehicle travels in a predetermined target driving state without the need for acceleration / deceleration operation by the driver. That is, the vehicle 10 of this embodiment is capable of auto-cruise driving, which automatically controls the engine 32 and the rotary machine MG according to a target vehicle speed Vt, etc., in addition to manual driving in which the engine 32 and the rotary machine MG are controlled according to the driver's acceleration / deceleration operation using the accelerator pedal, etc. In addition to selecting auto-cruise driving, the auto-cruise setting device 110 is a device for setting a target vehicle speed Vt, increasing / decreasing the target vehicle speed Vt, setting a target inter-vehicle distance Dt during following driving in which the vehicle travels following a preceding vehicle, etc., and is disposed on, for example, a steering wheel, and the target vehicle speed Vt, the target inter-vehicle distance Dt, etc. are input by the driver as auto-cruise setting information Acrui.

[0036] The on-board control device 130 outputs various command signals (e.g., an engine control command signal Se for controlling the engine 32, an MG control command signal Smg for controlling the rotary machine MG, an LU control command signal Slu for controlling the LU clutch 70, a shift control command signal Ssh for switching the gear stage of the shift unit 64, etc.) for controlling each device (e.g., the engine 32, the rotary machine MG, the LU clutch 70, the transmission unit 64, etc.) provided in the vehicle 10. The vehicle 10 also includes an automatic brake system 80 in relation to the auto-cruise running. The automatic brake system 80 electrically controls the braking force, i.e., the brake hydraulic pressure, of each wheel brake 82 provided on the rear wheels 52 and the front wheels 54 in accordance with an automatic brake control command signal Sbr supplied from the on-board control device 130. The wheel brakes 82 are also supplied with brake hydraulic pressure via a brake master cylinder by stepping on a brake pedal (not shown), and mechanically generate a brake force according to the brake hydraulic pressure, i.e., the brake operation force.

[0037] The on-board control device 130 functionally comprises a hybrid control unit 132, a gear shift control unit 134, and an auto-cruise control unit 136 in order to realize various controls in the vehicle 10.

[0038] The hybrid control unit 132 controls the operation of the engine 32 and the rotary machine MG in a coordinated manner. The hybrid control unit 132 calculates a driving demand amount for the vehicle 10 by the driver, for example, by applying the accelerator opening θacc and the vehicle speed V to a driving demand amount map. The driving demand amount is, for example, a required driving force Frdem and a required driving torque Trdem at the rear wheels 52. The hybrid control unit 132 calculates, for example, a required TC input torque Ttcdem, which is an input torque of the torque converter 62 required to realize the required driving torque Trdem, taking into consideration a transmission loss, an auxiliary load, a gear ratio γ of the transmission unit 64, a torque ratio of the torque converter 62, and the like, and outputs an engine control command signal Se for controlling the engine 32 and an MG control command signal Smg for controlling the rotary machine MG so that the required TC input torque Ttcdem is obtained.

[0039] When the required TC input torque Ttcdem can be met only by the output of the rotary machine MG, the hybrid control unit 132 selects a BEV (Battery Electric Vehicle) driving mode, which is a motor driving mode in which the rotary machine MG is driven to drive the vehicle. In the BEV driving mode, the engine 32 is stopped, and the vehicle is driven in a BEV driving mode in which the vehicle is driven only by the rotary machine MG as a driving force source. When an engine disconnecting device is provided between the rotary machine MG and the engine 32, it is desirable to open the engine disconnecting device and disconnect the engine 32 from the power transmission path to prevent the engine 32 from rotating together. In the BEV driving mode, the MG torque Tmg is controlled so as to realize the required TC input torque Ttcdem. On the other hand, when the required TC input torque Ttcdem cannot be met without using at least the output of the engine 32, the hybrid control unit 132 selects an HEV (Hybrid Electric Vehicle) driving mode, which is an engine driving mode. In the HEV driving mode, the vehicle is driven in an engine driving mode in which the vehicle is driven in a HEV driving mode in which the vehicle is driven in a HEV driving mode in which the vehicle is driven in a HEV driving mode, which is an engine driving mode in which the vehicle is driven in a HEV driving mode, at least the engine 32 is used as a driving force source. In this HEV driving mode, the engine torque Te is controlled to realize all or a part of the required TC input torque Ttcdem, and the MG torque Tmg is controlled to compensate for the torque that is insufficient in the engine torque Te relative to the required TC input torque Ttcdem. On the other hand, even if the required TC input torque Ttcdem can be satisfied only by the output of the rotary machine MG, the hybrid control unit 132 establishes the HEV driving mode when warming up of the engine 32 or the like is required. In this way, the hybrid control unit 132 switches between the BEV driving mode and the HEV driving mode by automatically stopping the engine 32 during HEV driving, restarting the engine 32 after the engine has stopped, starting the engine 32 during BEV driving, automatically stopping the engine 32 while the vehicle is stopped, and starting the engine 32, based on the required TC input torque Ttcdem, etc.

[0040] When the D range is selected, the shift control unit 134 performs automatic shift control by making a shift decision of the shift unit 64 according to a shift condition such as a shift map determined in advance using the driving state such as the vehicle speed V and the required driving torque Trdem as variables, and outputting a shift control command signal Ssh for automatically switching the multiple forward gears of the shift unit 64 as necessary. FIG. 4 shows an example of a shift map when the shift unit 64 is equipped with the four-speed transmission of FIG. 2, which is determined using the required driving torque Trdem and the vehicle speed V as variables, with the solid line being an upshift line for deciding whether to upshift, and the dashed line being a downshift line for deciding whether to downshift. This shift map is determined so that the driving force source (the engine 32 and the rotary machine MG) is operated in an appropriate operating region, such as a torque region or a rotation speed region, according to the required driving torque Trdem and the vehicle speed V. Specifically, it is set that the higher the vehicle speed V or the lower the required driving torque Trdem, the smaller the gear ratio γ becomes in the higher gear, and the lower the vehicle speed V or the larger the required driving torque Trdem, the larger the gear ratio γ becomes in the lower gear. The numbers "1" to "4" in FIG. 4 represent the first gear "1st" to the fourth gear "4th". The required driving torque Trdem corresponds to the driving demand amount, and the required driving force Frdem or the accelerator opening θacc may be used instead of the required driving torque Trdem. Also, the output rotation speed No may be used instead of the vehicle speed V.

[0041] The transmission control unit 134 also performs manual transmission control to switch the forward gears of the transmission unit 64 in accordance with a transmission instruction signal when the driver operates the shift lever 122 or a manual transmission operating member provided near the driver's seat and supplies the transmission instruction signal.

[0042] The auto-cruise control unit 136 executes auto-cruise driving as an automatic driving. Auto-cruise driving is autonomous driving without the need for acceleration / deceleration operation by the driver, and executes constant speed driving control for constant speed driving at the target vehicle speed Vt set by the auto-cruise setting device 110, and follow-up driving control for following while maintaining the target inter-vehicle distance Dt set by the auto-cruise setting device 110. In the constant speed driving control, a required driving torque Trdem required for driving at the target vehicle speed Vt is calculated, and a required TC input torque Ttcdem required for realizing the required driving torque Trdem is obtained in consideration of a transmission loss, an auxiliary load, a gear ratio γ of the transmission unit 64, a torque ratio of the torque converter 62, and the like. Then, an engine control command signal Se for controlling the engine 32 is outputted so that the required TC input torque Ttcdem is obtained, and an MG control command signal Smg for controlling the rotary machine MG is outputted. 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 vehicle speed Vt and the actual vehicle speed V. On the other hand, in the follow-up running control in which the vehicle follows the preceding vehicle 56 while maintaining the target inter-vehicle distance Dt, the required driving torque Trdem required for following the preceding vehicle 56 while the inter-vehicle distance Dis is the target inter-vehicle distance Dt is calculated, and the engine torque Te and the MG torque Tmg are controlled so that the required driving torque Trdem is obtained. The target inter-vehicle distance Dt is variably set according to the vehicle speed V, for example. In addition, when the required driving torque Trdem is negative, such as when the preceding vehicle 56 is decelerating, regenerative braking is generated by the engine brake or the rotary machine MG, and, if necessary, a negative required driving torque Trdem is obtained by combining it with the braking force of the wheel brake 82 controlled by the automatic brake system 80. In this embodiment, the auto-cruise control unit 136 corresponds to the follow-up running control unit that executes the follow-up running control.

[0043] During the above-mentioned auto-cruise running, manual shift control by the shift control unit 134 is prohibited, and automatic shift control is performed to automatically switch between the four forward gears in accordance with a predetermined normal shift map M1 as shown in Fig. 4. In this case, during following running in which the vehicle follows a preceding vehicle 56, particularly during platooning in which the vehicle follows a preceding vehicle 56 over a relatively long distance on a highway or a motorway, the presence of the preceding vehicle 56 may reduce the amount of ventilation air, causing the oil temperature THoil to rise excessively. For this reason, in this embodiment, a high oil temperature shift map M2 as shown in Fig. 5 is prepared in addition to the normal shift map M1 as shown in Fig. 4, and the shift control unit 134 performs automatic shift control of the shift unit 64 while changing the shift maps M1 and M2 according to the oil temperature THoil during following running. The high oil temperature shift map M2 in Fig. 5 is a map in which the shift lines (upshift lines and downshift lines) are shifted toward the lower vehicle speed side, so that the gears are switched at lower vehicle speeds, i.e., so that the higher gears are used more frequently, as compared with the normal shift map M1 in Fig. 4. Fig. 5 shows that all the shift lines are simply shifted in parallel toward the lower vehicle speed side, but various modes are possible, such as only shifting either the upshift lines or the downshift lines toward the lower vehicle speed side, only shifting some of the shift lines (e.g., the side where the required driving torque Trdem is high) toward the lower vehicle speed side, or only shifting some of the gear shift lines (e.g., the shift line between the third gear "3rd" and the fourth gear "4th") toward the lower vehicle speed side. The normal shift map M1 corresponds to a normal shift condition, and the high oil temperature shift map M2 corresponds to a high oil temperature shift condition.

[0044] The gear shift control unit 134 selects a gear shift map in accordance with steps S1 to S10 (hereinafter, the steps will be omitted and simply referred to as S1 to S10. The same applies to other flowcharts.) in the flowchart, and executes automatic gear shift control using the selected gear shift map. In the flowchart, YES in the decision steps indicated by diamonds means affirmative, and NO means negative.

[0045] In S1 of Fig. 6, it is determined whether or not the vehicle is in follow-up driving, in which the auto-cruise control unit 136 is executing follow-up driving control. Whether or not the vehicle is in follow-up driving can be determined, for example, from the operation state of the auto-cruise setting device 110, the driving state of the vehicle 10, or the operating state of the auto-cruise control unit 136, or from the state of a follow-up driving flag that is switched ON or OFF depending on whether or not follow-up driving control is being executed. If the vehicle is not in follow-up driving, S10 is executed to select the normal-time shift map M1 in Fig. 4, and if the vehicle is in follow-up driving, S2 and subsequent steps are executed. In S2, it is determined whether or not the normal-time shift map M1 is selected, and if the normal-time shift map M1 is selected, S3 and subsequent steps are executed, and if the normal-time shift map M1 is not selected, i.e., if the high oil temperature shift map M2 is selected, S9 is executed.

[0046] In S9, it is determined whether or not the return condition to the normal shift map M1 is satisfied. If the return condition is not satisfied, S8 is executed to maintain the selection state of the high oil temperature shift map M2, but if the return condition is satisfied, S10 selects the normal shift map M1. The high oil temperature shift map M2 is selected in S8 when the oil temperature THoil is equal to or higher than the high oil temperature judgment value THs and the judgment in S7 is YES. Therefore, the return condition may be determined to be that the oil temperature THoil is lower than the high oil temperature judgment value THs. However, in this embodiment, in order to prevent the shift maps M1 and M2 from being frequently switched, the return condition is determined to be equal to or lower than a return judgment value THre that is lower than the high oil temperature judgment value THs. The return judgment value THre is determined to be a value lower than the high oil temperature judgment value THs by a predetermined constant temperature or a value lower by a certain percentage. Also, apart from the return condition related to the oil temperature THoil, it is desirable to return to the normal-time shift map M1, for example, when it is not appropriate to continue the automatic shift control under shift conditions other than the normal-time shift map M1. For example, when a solenoid valve, a rotation speed sensor, or the like involved in the shift has a failure, the automatic shift control itself may not be performed properly, and when such a failure occurs, various controls are performed on the premise that the shift control is performed according to the normal-time shift map M1. Therefore, the detection of a failure of a part involved in the shift may also be specified as a return condition, and the determination in S9 becomes YES, and the normal-time shift map M1 may be selected in S10.

[0047] If the determination in S2 is YES, that is, if the normal shift map M1 is selected, the vehicle distance Dis between the vehicle 10 and the preceding vehicle 56 is read in S3, the projected area Apr seen from the rear side of the preceding vehicle 56 is calculated in S4, and the expected load Lex, which is the future expected driving load of the vehicle 10, is calculated in S5. The vehicle distance Dis is detected by the vehicle distance sensor 108, and may be an instantaneous value, but for example, an average value for a predetermined fixed driving time or a predetermined driving distance may also be used. The projected area Apr can be obtained, for example, from a video image Vfr captured by the vehicle front capturing camera 106, but the projected area Apr can also be calculated by measuring the width dimension Wpr and height dimension Hpr of the rear of the preceding vehicle 56 by a sensor. In addition, if the projected area Apr is stored in advance together with the type and identification number of the preceding vehicle 56 in the platooning, the projected area Apr can be read from the identification number, etc., or the projected area Apr can be read by vehicle-to-vehicle communication with the preceding vehicle 56, and various other modes are possible. The expected load Lex can be calculated from a travel route preset in the navigation system 84 having road information including altitude, for example. Specifically, for example, the total energy required for travel [J], the average output [W] of the required output for the engine 32 and the rotary machine MG, the travel resistance [N] such as air resistance, power transmission loss, and rolling resistance, the total travel distance [km], the accumulated elevation difference [m], etc. can be used as the expected load Lex. In addition, the expected load Lex may be, for example, a moving average from the current position to several kilometers to several tens of kilometers ahead. Past travel load data on the same travel route may be stored and read. The travel load data may be stored in a server of a platoon management center or the like, and read from the server via a wireless communication line.

[0048] The above-mentioned inter-vehicle distance Dis, projected area Apr, and expected load Lex are all oil temperature influencing factors that affect the oil temperature THoil during following driving. Among these oil temperature influencing factors, the inter-vehicle distance Dis and projected area Apr correspond to information on the preceding vehicle 56 that affects the ventilation air volume of the vehicle 10. Then, in the next S6, the high oil temperature judgment value THs is calculated based on the inter-vehicle distance Dis, projected area Apr, and expected load Lex. For example, as shown in FIG. 8, the high oil temperature judgment reference value THsst is calculated based on the inter-vehicle distance Dis from a predetermined map or relational expression, as shown in FIG. 9, the correction coefficient Ka is calculated based on the projected area Apr from a predetermined map or relational expression, as shown in FIG. 10, the correction coefficient Kl is calculated based on the predicted load Lex from a predetermined map or relational expression, and the high oil temperature judgment reference value THsst, the correction coefficient Ka, and the correction coefficient Kl are multiplied together as shown in the following equation (1) to calculate the high oil temperature judgment value THs. That is, for the vehicle distance Dis, the smaller the vehicle distance Dis, the smaller the ventilation air volume and the easier it is for the oil temperature THoil to rise, so in Fig. 8, the smaller the vehicle distance Dis, the lower the high oil temperature judgment reference value THsst is set. For the projected area Apr, the larger the projected area Apr, the smaller the ventilation air volume and the easier it is for the oil temperature THoil to rise, so in Fig. 9, the larger the projected area Apr, the smaller the correction coefficient Ka becomes below 1.0 and the lower the high oil temperature judgment value THs is set. For the expected load Lex, the larger the expected load Lex, the more frequently the low-speed gear stage is used, and the rotation speed of each part of the transmission unit 64 and the rotation speed of the torque converter 62 become faster, and the oil temperature THoil is more likely to rise due to oil agitation, so in Fig. 10, the larger the expected load Lex, the smaller the correction coefficient Kl becomes below 1.0 and the lower the high oil temperature judgment value THs is set. THs =THsst ×Ka ×Kl (1)

[0049] In FIG. 8, the high oil temperature judgment reference value THsst is calculated according to the vehicle distance Dis. However, a certain high oil temperature judgment reference value THsst may be determined in advance, and a correction coefficient Kd may be calculated for the vehicle distance Dis in the same manner as for the projected area Apr and the expected load Lex, and the high oil temperature judgment reference value THs may be multiplied by the correction coefficient Kd to calculate the high oil temperature judgment value THs. The high oil temperature judgment reference value THsst may be calculated from the projected area Apr or the expected load Lex. The high oil temperature judgment value THs may be variably set using only one of the vehicle distance Dis and the projected area Apr, which are information about the preceding vehicle 56 that affects the ventilation air volume, as a variable. The high oil temperature judgment value THs may be calculated in consideration of other information about the preceding vehicle 56 that affects the ventilation air volume instead of or in addition to the vehicle distance Dis, the projected area Apr, and the expected load Lex. For example, the width dimension Wpr and height dimension Hpr of the rear of the preceding vehicle 56 may be calculated from the video image Vfr, and the correction coefficients Kw and Kh may be obtained from a predetermined map, and the high oil temperature judgment reference value THsst may be multiplied by the correction coefficients Kw and Kh to calculate the high oil temperature judgment value THs. Fig. 11 shows an example of a map or formula for calculating the correction coefficient Kw based on the width dimension Wpr. As in the case of the projected area Apr, the larger the width dimension Wpr, the smaller the ventilation air volume and the easier it is for the oil temperature THoil to rise. Therefore, the correction coefficient Kw is set to be smaller than 1.0 and the high oil temperature judgment value THs is set to be lower as the width dimension Wpr increases. As for the height dimension Hpr, the larger the height dimension Hpr, the smaller the ventilation air volume and the easier it is for the oil temperature THoil to rise. Therefore, the correction coefficient Kh is set to be smaller than 1.0 as the height dimension Hpr increases. In Figures 9 to 11, the correction coefficients Ka, Kl, and Kw each vary across 1.0, but depending on how the high oil temperature judgment reference value THsst is determined, it is also possible to simply vary these correction coefficients Ka, Kl, and Kw within a range of 1.0 or less.In addition, for the maps or arithmetic expressions in FIGS. 8 to 11, although the high oil temperature determination reference value THsst, correction coefficients Ka, Kl, and Kw all change linearly with variables such as the inter-vehicle distance Dis, they may also change in a broken line or curve, or may change in multiple steps of two steps or three or more steps. Various modes are possible.

[0050] In S7 of FIG. 6, it is determined whether the oil temperature THoil is equal to or higher than the high oil temperature determination value THs obtained in S6. If THoil ≧ THs, S8 is executed to select the high oil temperature shift map M2 in FIG. 5. If THoil < THs, S10 is executed to select the normal shift map M1 in FIG. 4.

[0051] FIG. 12 is an example of a time chart showing the change in the oil temperature THoil and the shift maps M1 and M2 when the shift maps M1 and M2 are changed according to the flowchart in FIG. 6 during following driving. The time t1 in FIG. 12 is the time when the oil temperature THoil becomes equal to or higher than the high oil temperature determination value THs, the determination in S7 becomes YES, S8 is executed, and the high oil temperature shift map M2 is selected. When changed to the high oil temperature shift map M2 in this way, since the high-speed side gear stages are used more frequently, the rotational speeds of each part of the transmission unit 64 and the rotational speed of the torque converter 62 decrease, and the temperature rise due to oil agitation is suppressed. In addition, since the gear stages of the transmission unit 64 are switched at a lower vehicle speed than in the normal state, the change in the rotational speed during shifting of the engagement device CB that is engaged during shifting becomes smaller as the vehicle speed V is lower, and the load (heat generation amount) during engagement is reduced, suppressing the rise in the oil temperature THoil. As a result, the oil temperature THoil is reduced. When it becomes equal to or lower than the return determination value THre at time t2, the determination in S9 becomes YES, S10 is executed, and it returns to the normal shift map M1.

[0052] On the other hand, when the shift control is performed according to the high oil temperature shift map M2 in this way, the high-speed gear stage is used frequently, so that the engine 32 and the rotary machine MG, which are the driving force sources, are operated in a high torque region, which may result in poor responsiveness to the required drive torque Trdem. As a result, the change in the inter-vehicle distance Dis during following driving becomes large, while the change in the required drive torque Trdem becomes large in order to suppress the change in the inter-vehicle distance Dis, and a busy shift in which the gear stage is frequently changed due to the change in the required drive torque Trdem is likely to occur, which may cause the driver to feel uncomfortable. For this reason, the auto-cruise control unit 136 of this embodiment executes signal processing according to the flowchart of FIG. 7, and is configured to limit following driving under certain conditions when the high oil temperature shift map M2 is selected.

[0053] In SS1 of FIG. 7, it is determined whether the high oil temperature shift map M2 is selected, and if the high oil temperature shift map M2 is selected, SS2 and subsequent steps are executed. If the high oil temperature shift map M2 is not selected, that is, if the normal shift map M1 is selected, the process ends. In SS2, it is determined whether it is appropriate to continue the following running control, and in this embodiment, whether a following running impossible condition is met for which following running should be stopped. The following running impossible condition is determined in advance as a vehicle state that causes a driver to feel uncomfortable, such as when the inter-vehicle distance Dis is significantly deviated from the target inter-vehicle distance Dt, when a state in which the inter-vehicle distance is greater than or equal to a certain value continues for a certain period of time, when the inter-vehicle distance is greater than or equal to a certain value frequently occurs, when the engine torque Te or the MG torque Tmg of the driving force source torque changes by a large amount, or when the driving force source torque changes frequently. Then, when the following running impossible condition is met, SS3 and subsequent steps are executed, and when the following running impossible condition is not met, the process ends.

[0054] In SS3, the driver is notified of the non-following running information, which indicates that the following running should be stopped, by a sound or an image, etc., using a display device near the driver's seat. In SS4, it is determined whether the driver has performed an operation to end the following running using the auto-cruise setting device 110. If the driver has performed an operation to end the following running, SS5 is executed to end the following running control, but if the driver has not performed an operation to end the following running control, the following running control is continued as is. When the end process of the following running control is performed in SS5, the determination in S1 of FIG. 6 becomes NO, and the normal time shift map M1 is selected in S10, and the shift control of the shift unit 64 is performed using the normal time shift map M1. In this way, the case where the driver is notified of the non-following running information and the following running control is ended on the condition of the driver's end operation is also one aspect of restricting the following running control. It is also possible to forcibly end the following running control by omitting SS4.

[0055] According to the shift control unit 134 functionally provided in the vehicle-mounted control device 130 of the vehicle 10 of this embodiment, while the following running control is being performed, the high oil temperature judgment value THs is variably set based on information (inter-vehicle distance Dis, projected area Apr) about the preceding vehicle 56 that affects the ventilation air volume, while the oil temperature THoil of the transmission unit 64 is detected, and when the oil temperature THoil is equal to or higher than the high oil temperature judgment value THs, the high oil temperature shift map M2 in which the gear stage is switched to the low vehicle speed side is selected (S7, S8), and the high-speed gear stage with a small gear ratio γ is used frequently. When the high-speed gear stage is used frequently in this manner, the rotation speed of each part of the transmission unit 64 including the input rotation speed Ni and the rotation speed of the torque converter 62 are reduced, and heat generation due to stirring of the oil is suppressed, so that the oil temperature THoil is prevented from rising due to a decrease in cooling performance caused by a decrease in the ventilation air volume during following running. In particular, since the high oil temperature judgment value THs for determining whether or not to change the shift maps M1, M2 is variably set based on information about the preceding vehicle 56 that affects the ventilation air volume, it is possible to appropriately suppress the rise in the oil temperature THoil caused by the reduction in the ventilation air volume during following travel. As a result, it is possible to suppress an excessive rise in the oil temperature caused by the reduction in the ventilation air volume while enjoying the effect of improving fuel efficiency by reducing the running resistance caused by the preceding vehicle 56 acting as a windbreak during following travel.

[0056] In addition, the transmission 64 is a stepped transmission in which gears are changed by changing the engagement and release state of multiple engagement devices CB, and when the high oil temperature shift map M2 is selected and the gears are changed to the low vehicle speed side, the change in rotational speed of the engagement devices CB that are engaged during the shift is smaller since the vehicle speed V is lower, and the load (heat generation) during the engagement is reduced, which also suppresses the rise in the oil temperature THoil.

[0057] In addition, a determination is made as to whether or not the oil temperature THoil has reached or exceeded the high oil temperature determination value THs set in S6, and if it has reached or exceeded the high oil temperature determination value THs, the high oil temperature shift map is changed to M2, thereby making it possible to easily implement the present invention in which the rotational speed of each part of the transmission 64 is reduced to suppress the rise in the oil temperature THoil.

[0058] Furthermore, the vehicle distance Dis to the preceding vehicle 56 is used as information regarding the preceding vehicle 56 that affects the ventilation air volume, and the high oil temperature determination value THs is variably set according to the vehicle distance Dis so that when the vehicle distance Dis is small, the high oil temperature determination value THs is lower than when the vehicle distance Dis is large, thereby appropriately suppressing the rise in the oil temperature THoil. In other words, when the vehicle distance Dis is small, the deterioration in cooling performance due to the reduction in the ventilation air volume caused by the preceding vehicle 56 becomes significant, so by lowering the high oil temperature determination value THs and changing to the high oil temperature shift map M2 at a lower oil temperature THoil, the rise in the oil temperature THoil can be appropriately suppressed regardless of the deterioration in cooling performance.

[0059] In addition, the projected area Apr seen from the rear side of the preceding vehicle 56 is used as information on the preceding vehicle 56 that affects the ventilation air volume, and the high oil temperature determination value THs is variably set according to the projected area Apr so that when the projected area Apr is large, the high oil temperature determination value THs is lower than when the projected area Apr is small, so that the rise in the oil temperature THoil is appropriately suppressed. In other words, when the projected area Apr of the preceding vehicle 56 is large, the deterioration in cooling performance due to the reduction in the ventilation air volume caused by the preceding vehicle 56 becomes significant, so by lowering the high oil temperature determination value THs and changing to the high oil temperature shift map M2 at a lower oil temperature THoil, the rise in the oil temperature THoil can be appropriately suppressed regardless of the deterioration in cooling performance.

[0060] Furthermore, since the high oil temperature determination value THs is variably set based on the expected load Lex as well as information about the preceding vehicle 56 that affects the ventilation air volume so that the high oil temperature determination value THs is lower when the expected load Lex is large compared to when it is small, the rise in the oil temperature THoil is more appropriately suppressed. In other words, when the expected load Lex is large, the lower gear stage with the larger gear ratio γ is used more frequently due to a decrease in vehicle speed V, making it easier for the oil temperature THoil to rise, so by lowering the high oil temperature determination value THs and changing to the high oil temperature shift map M2 at a lower oil temperature THoil, the rise in the oil temperature THoil caused by a large traveling load can be appropriately suppressed.

[0061] In addition, since the expected load Lex is calculated based on a predetermined driving route, the expected load Lex can be appropriately predicted and the high oil temperature determination value THs can be lowered, thereby appropriately suppressing the rise in the oil temperature THoil.

[0062] Furthermore, when the shift control unit 134 changes to the high oil temperature shift map M2 while the follow-up travel control is being performed, the auto-cruise control unit 136 determines whether follow-up travel can be continued (SS2), and if it determines that follow-up travel is not possible, notifies the driver of the follow-up travel impossibility information (SS3). Then, since the follow-up travel control is ended on the condition that the driver performs an end operation (SS4, SS5), it is possible to prevent the driver from feeling uncomfortable due to a large change in the inter-vehicle distance Dis from the preceding vehicle 56, a large change in the torque of the driving force source, or the occurrence of a busy shift caused by the continuation of the follow-up travel control in an unreasonable manner.

[0063] In addition, when the oil temperature THoil becomes equal to or higher than the high oil temperature judgment value THs, the map is switched to the high oil temperature shift map M2. However, the map is returned to the normal operation shift map M1 from the high oil temperature shift map M2 only when the oil temperature THoil becomes equal to or lower than the return judgment value THre, which is lower than the high oil temperature judgment value THs. This prevents the map M1 and M2 from being frequently switched between due to slight up and down changes in the oil temperature THoil.

[0064] Furthermore, when setting the high oil temperature judgment value THs in S6, the width dimension Wpr of the rear of the preceding vehicle 56 is taken into consideration as information on the preceding vehicle 56 that affects the ventilation air volume, and the high oil temperature judgment reference value THsst is multiplied by a correction coefficient Kw, which becomes smaller than 1.0 as the width dimension Wpr increases, as shown in Fig. 11, to calculate the high oil temperature judgment value THs, so that the increase in the oil temperature THoil can be appropriately suppressed. In other words, when the width dimension Wpr of the preceding vehicle 56 is large, the decrease in cooling performance due to the decrease in the ventilation air volume caused by the preceding vehicle 56 becomes significant, so that the increase in the oil temperature THoil can be appropriately suppressed regardless of the decrease in cooling performance by lowering the high oil temperature judgment value THs and changing to the high oil temperature shift map M2 at a lower oil temperature THoil. The same effect can be obtained by taking into consideration the height dimension Hpr of the rear of the preceding vehicle 56 and calculating the correction coefficient Kh in the same way as the width dimension Wpr to set the high oil temperature judgment value THs.

[0065] Although the embodiment of the present invention has been described in detail above with reference to the drawings, this is merely one embodiment, and the present invention can be implemented in various forms with various modifications and improvements based on the knowledge of those skilled in the art. [Explanation of symbols]

[0066] 10: Vehicle 32: Engine (power source) 56: Leading vehicle 64: Transmission unit (automatic transmission) 130: On-board control device (control device) 134: Transmission control unit 136: Auto-cruise control unit (follow-up driving control unit) MG: Rotating machine (power source) M1: Normal shift map (normal shift conditions) M2: High oil temperature shift map (high oil temperature shift conditions) THoil: Oil temperature THs: High oil temperature judgment value THre: Recovery judgment value Dis: Inter-vehicle distance Apr: Projected area Wpr: Width dimension Lex: Expected load

Claims

1. A vehicle having a driving force source and an automatic transmission capable of changing a gear ratio, a follow-up running control unit that controls an output of the driving force source so that the vehicle follows the preceding vehicle at a predetermined target vehicle distance without requiring an acceleration / deceleration operation by a driver; a gear shift control unit that changes a gear ratio of the automatic transmission in accordance with a predetermined gear shift condition; In a control device for a vehicle having The shift control unit variably sets a high oil temperature determination value based on information about the preceding vehicle that affects the ventilation air volume while the following drive control unit is performing the following drive control, and detects an oil temperature of the automatic transmission, and when the oil temperature is equal to or higher than the high oil temperature determination value, changes the shift conditions based on the oil temperature so that a higher speed side gear ratio having a smaller gear ratio is used more frequently than when the oil temperature is lower than the high oil temperature determination value. A vehicle control device comprising:

2. The information regarding the preceding vehicle is a distance between the vehicle and the preceding vehicle, The shift control unit variably sets the high oil temperature determination value in accordance with the inter-vehicle distance so that the high oil temperature determination value is lower when the inter-vehicle distance is small compared to when the inter-vehicle distance is large.

2. The vehicle control device according to claim 1.

3. the information about the preceding vehicle is a width dimension of a rear portion of the preceding vehicle; The shift control unit variably sets the high oil temperature determination value in accordance with the width dimension such that the high oil temperature determination value is lower when the width dimension is large than when the width dimension is small.

2. The vehicle control device according to claim 1.

4. the information about the preceding vehicle is a projected area of ​​the preceding vehicle as seen from a rear side; The shift control unit variably sets the high oil temperature determination value in accordance with the projected area such that the high oil temperature determination value is lower when the projected area is large than when the projected area is small.

2. The vehicle control device according to claim 1.

5. The shift control unit variably sets the high oil temperature determination value based on the expected load in addition to information about the preceding vehicle so that the high oil temperature determination value is lower when the expected load, which is a future expected running load of the vehicle, is large compared to when the expected load is small.

2. The vehicle control device according to claim 1.

6. The predicted load is calculated based on a predetermined travel route.

6. The vehicle control device according to claim 5.

7. When the shift control unit changes the gear shift conditions so that the high-speed gear ratio is frequently used during execution of the following running control, the following running control unit determines whether or not it is appropriate to continue the following running control, and limits the following running control when it determines that it is inappropriate to continue the following running control.

2. The vehicle control device according to claim 1.

8. The shift control unit switches from a normal shift condition to a high oil temperature shift condition in which the high speed side gear ratio is frequently used when the oil temperature is equal to or higher than the high oil temperature judgment value, and returns from the high oil temperature shift condition to the normal shift condition on the condition that the oil temperature becomes equal to or lower than a return judgment value that is lower than the high oil temperature judgment value.

2. The vehicle control device according to claim 1.

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