Vehicle control device

Abstract

To provide a vehicle control device enabling a vehicle to deliver travel performance thereof even when a garage shift is performed with a wheel put in a slipped state.SOLUTION: A vehicle control device is for a vehicle which comprises an engine and an automatic transmission enabling manual operation to switch between a forward driving position (D range) and a backward traveling position (R range) and performs torque limit control limiting transmission torque, the torque transmitted through the automatic transmission when a garage shift repeatedly switching between the forward traveling position and the backward traveling position is performed. The vehicle control device lifts or relaxes a limit on the transmission torque under the torque limit control when the garage shift is performed with a drive wheel put in a slipped state (Steps S3, S4 and S5).SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to a control device for a vehicle equipped with an automatic transmission, and more particularly to a control device for a vehicle that controls the vehicle in response to a situation where a shift operation (garage shift) that repeats forward and reverse is performed by a driver's shift operation.

Background Art

[0002] Patent Document 1 describes a vehicle control device aimed at suppressing overheating of a friction material in a friction engagement element when switching between forward and reverse during a garage shift. The vehicle control device described in this Patent Document 1 controls a vehicle equipped with an engine, a planetary gear device, and a forward / reverse switching mechanism having friction engagement elements (clutches, brakes). In the vehicle control device described in this Patent Document 1, when a so-called garage shift is performed in which a shift device is switched between a forward driving range (D range) and a reverse driving range (R range), throttle closing control is executed to suppress the output torque of the engine by setting the throttle opening degree of the engine to be equal to or less than the upper limit value. At the same time, in the vehicle control device described in this Patent Document 1, when the absolute value of the difference in rotational speed before and after in the friction engagement element becomes equal to or less than a first predetermined value, and the absolute value of the sum of the rotational speeds before and after in the friction engagement element becomes equal to or less than a second predetermined value, a return control is executed to change the upper limit value of the throttle opening degree from a first opening degree corresponding to idling to a second opening degree that is larger than the first opening degree and smaller than a value corresponding to the driver's operation amount.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] Conventionally, in vehicles equipped with an automatic transmission or a forward and reverse switching mechanism, like the vehicle control device described in Patent Document 1, during a garage shift, the output torque of the engine is restricted by the throttle closing control as described above to prevent or suppress overheating of the friction material and protect the automatic transmission and the forward and reverse switching mechanism. On the other hand, for example, when the wheels slip on a muddy road, sandy ground, or a rough road with severe unevenness and the vehicle gets stuck, an operation called "rocking out" may be performed, where the vehicle is rocked back and forth by repeatedly moving forward and backward to escape from the stuck state. That is, it is assumed that the above-described garage shift is performed while the wheels are slipping. When the garage shift is performed in a state where such wheel slip has occurred, if the above-described throttle closing control is executed, even though a large driving force is required to escape from the stuck state, the output torque of the engine is restricted. As a result, there is a risk that the running performance of the vehicle will deteriorate.

[0005] This invention was conceived by focusing on the above technical problem, and an object of the invention is to provide a vehicle control device capable of avoiding or suppressing deterioration of the running performance of the vehicle even when a garage shift is performed in a state where wheel slip has occurred.

Means for Solving the Problem

[0006] In order to achieve the above object, the present invention provides a driving power source that outputs torque for driving driving wheels, a controller that changes the rotational speed of the output shaft of the driving power source, and transmits the torque between the driving power source and the driving wheels, and an automatic transmission that allows a driver to manually switch and set a forward driving position and a reverse driving position. In a vehicle control device that executes torque limit control for limiting the transmission torque transmitted by the automatic transmission when a garage shift in which a switching operation between the forward driving position and the reverse driving position is repeated is performed, the vehicle control device includes a controller that controls the driving power source and the automatic transmission respectively. When the garage shift is performed while slip occurs in the driving wheels, the controller releases the restriction on the transmission torque by the torque limit control, or relaxes the restriction on the transmission torque by the torque limit control.

[0007] Note that the torque limit control in the present invention may include control for limiting the transmission torque by providing a limit on the magnitude of the output torque of the driving power source. The controller in the present invention may be configured to release the restriction on the magnitude of the output torque, or relax the restriction on the magnitude of the output torque, thereby releasing the restriction on the transmission torque, or relaxing the restriction on the transmission torque.

[0008] Also, the torque limit control in the present invention may include control for limiting the transmission torque by providing a limit on the shifting operation of the automatic transmission. The controller in the present invention may be configured to release the restriction on the shifting operation of the automatic transmission, or relax the restriction on the shifting operation of the automatic transmission, thereby releasing the restriction on the transmission torque, or relaxing the restriction on the transmission torque.

Advantages of the Invention

[0009] When a so-called garage shift, which repeatedly switches the shift position of the automatic transmission between the forward driving position (e.g., D range) and the reverse driving position (R range), is performed, torque limit control for limiting the transmission torque of the automatic transmission is executed to protect clutches, brakes, etc. in the automatic transmission. For example, by restricting the magnitude of the output torque of the driving power source, the transmission torque of the automatic transmission is restricted. Alternatively, by restricting the shifting operation of the automatic transmission, the transmission torque of the automatic transmission is restricted. And in the vehicle control device of this invention, when the above-described garage shift is performed in a situation where slip occurs in the driving wheels of the vehicle, the restriction on the transmission torque of the automatic transmission by the torque limit control is released. Alternatively, the restriction on the transmission torque of the automatic transmission by the torque limit control is relaxed. For example, by releasing the restriction on the magnitude of the output torque of the driving power source, the restriction on the transmission torque of the automatic transmission is released. Alternatively, by relaxing the restriction on the magnitude of the output torque of the driving power source, the restriction on the transmission torque of the automatic transmission is relaxed. Therefore, for example, when a garage shift is performed to escape from a situation where the wheels slip on a muddy road, sandy ground, or rough road and the vehicle gets stuck, the restriction on the transmission torque of the automatic transmission by the torque limit control is released or relaxed to generate a large driving force necessary to escape from the stuck state. Thus, according to the vehicle control device of this invention, even when a garage shift is performed in a state where the wheels are slipping, it is possible to avoid a decrease in the running performance of the vehicle and to exhibit the original running performance of the vehicle.

Brief Description of the Drawings

[0010]

Figure 1

Figure 2

Best Mode for Carrying Out the Invention

[0011] Embodiments of the present invention will be described with reference to the drawings. Note that the embodiments shown below are merely examples of implementing the present invention and do not limit the present invention.

[0012] In the embodiments of the present invention, the vehicle to be controlled includes a driving power source, driving wheels to which the output torque of the driving power source is transmitted to generate a driving force, a transmission mechanism that changes the rotational speed of the output shaft of the driving power source and transmits torque between the driving power source and the driving wheels, and a controller that controls the operations of the driving power source and the transmission. An example of the configuration (driving system and control system) of such a vehicle is shown in FIG. 1.

[0013] The vehicle Ve shown in FIG. 1 includes, as main components, a driving power source 1, driving wheels 2, an automatic transmission (AT) 3, a shift device 4, a detection unit 5, and a controller (ECU) 6.

[0014] The driving power source 1 outputs torque for driving the drive wheels 2, that is, torque for generating the driving force of the vehicle Ve. In the example shown in FIG. 2, an engine (ENG) 7 is provided as the driving power source 1. The engine 7 is, for example, an internal combustion engine such as a gasoline engine or a diesel engine, and is configured such that its output adjustment and operating states such as start and stop are electrically controlled. In the case of a gasoline engine, the opening degree of the throttle valve, the fuel supply amount or injection amount, the execution and stop of ignition, and the ignition timing are electrically controlled. In the case of a diesel engine, the fuel injection amount, the fuel injection timing, or the opening degree of the throttle valve (in the EGR system) is electrically controlled. Note that the driving power source 1 in the embodiment of the present invention may be, in addition to the engine 7 as described above, for example, a hybrid drive unit (not shown) that combines the engine 7 and a motor (motor generator) with an automatic transmission 3 described later, or a motor drive unit (not shown) that combines a motor with the automatic transmission 3 described later. In the vehicle control device in the embodiment of the present invention, a vehicle Ve having such a hybrid drive unit or motor drive unit as the driving power source 1 can also be made the object of control.

[0015] The drive wheel 2 is a wheel that generates the driving force of the vehicle Ve when the output torque of the driving force source 1 is transmitted. In the example shown in FIG. 2, the drive wheel 2 is the rear wheel of the vehicle Ve, and is connected to the output shaft 3b of the transmission 3 described later via the propeller shaft 8, the differential gear 9, and the left and right drive shafts 10. That is, in the example shown in FIG. 2, the vehicle Ve is a rear-wheel drive vehicle that uses the rear wheels as the drive wheels 2 and generates the driving force with the rear wheels. Note that the vehicle Ve in the embodiment of the present invention may be a front-wheel drive vehicle (not shown) that uses the front wheels as the drive wheels 2 and generates the driving force with the front wheels. Alternatively, the output torque of the driving force source 1 may be distributed to the front wheels and the rear wheels by a transfer (not shown), that is, a four-wheel drive (or all-wheel drive) vehicle (not shown) that uses the front wheels and the rear wheels as the drive wheels 2 and generates the driving force with those front wheels and rear wheels. Or, it may be a four-wheel drive (or all-wheel drive) hybrid vehicle (not shown) that drives either the front wheels or the rear wheels with the engine 7 and drives the other of the front wheels or the rear wheels with a motor.

[0016] The automatic transmission 3 is provided between the driving power source 1 and the driving wheels 2, and changes the rotational speed of the output shaft (for example, the output shaft 7a of the engine 7) of the driving power source 1. At the same time, the automatic transmission 3 transmits the output torque of the driving power source 1 between the driving power source 1 and the driving wheels 2. In the embodiment shown in FIG. 1, the automatic transmission 3 is connected to the output side of the engine 7 via a torque converter or the like (not shown), and transmits the output torque of the engine 7 to the driving wheels 2 side between the engine 7 and the driving wheels 2. And the automatic transmission 3 is a device that can appropriately change the ratio of the rotational speed of the output shaft 3b to the rotational speed of the input shaft 3a, that is, the gear ratio, and automatically controls the change of the gear ratio, that is, the shift control. Specifically, the automatic transmission 3 is a conventionally generally used vehicle transmission, for example, a stepped (multi-speed) "automatic transmission" that hydraulically controls the power transmission state between a plurality of planetary gear mechanisms (not shown). Or it may be an "automatic transmission" such as a so-called "dual clutch transmission" (DCT) using two systems of clutches and a constantly meshing gear mechanism. Or it may be an "automatic transmission" provided with a "forward and reverse switching mechanism" (not shown) that operates by hydraulic control, such as a "belt-type continuously variable transmission" (CVT) as described in Patent Document 1 above.

[0017] Also, the automatic transmission 3 performs shift operations such as changing the gear stage (gear ratio), switching the forward and reverse stages, and setting the neutral state by hydraulic control. Specifically, it hydraulically controls the operation of an engagement mechanism (not shown) configured inside the automatic transmission 3. For example, by hydraulically controlling the engagement and release operations of the clutches and brakes (not shown) provided inside the automatic transmission 3, the above-described shift operations are performed. In the case of a "belt-type continuously variable transmission" as described in Patent Document 1 above, the forward and reverse stages are switched by hydraulically controlling the operation of the "forward and reverse switching mechanism".

[0018] The shift device 4 has, for example, a shift lever (not shown) and a shift paddle (not shown), etc., and is operated by the driver. Specifically, the shift device 4 is manually operated by the driver to switch and set, as the shift positions of the automatic transmission 3, at least a forward travel position (drive position, or D range), a reverse travel position (reverse position, or R range), and a neutral position (or N range).

[0019] The detection unit 5 is a device or apparatus for acquiring various data and information necessary when controlling the vehicle Ve, and includes, for example, a power supply unit, a microcomputer, sensors, and input / output interfaces, etc. In particular, the detection unit 5 in the embodiment of this invention detects various data and information for controlling the drive power source 1 (engine 7) and the automatic transmission 3 respectively. Specifically, the detection unit 5 has at least various sensors such as a wheel speed sensor 5a for detecting the rotational speed of all wheels including the drive wheels 2, an engine speed sensor 5b for detecting the rotational speed of the output shaft 1a of the engine 7, an input shaft speed sensor 5c for detecting the rotational speed of the input shaft 3a (or a rotating member on the input shaft 3a side) of the automatic transmission 3, an output shaft speed sensor 5d for detecting the rotational speed of the output shaft 3b (or a rotating member on the output shaft 3b side) of the automatic transmission 3, a hydraulic pressure sensor 5e for detecting the engagement hydraulic pressure etc. for controlling the engagement mechanism (clutch, brake) of the automatic transmission 3, and a shift position sensor 5f for detecting the gear position of the automatic transmission 3 and the selected position of the shift device 4. In addition, the detection unit 5 may have a camera (not shown) for detecting or determining the slip state of the drive wheels 2, an acceleration sensor (not shown) for detecting the acceleration of the vehicle Ve, etc. And the detection unit 5 is electrically connected to a controller 6 described later, and outputs an electrical signal corresponding to the detection values or calculated values of the various sensors, devices, and apparatuses as described above to the controller 6 as detection data.

[0020] The controller 6 is an electronic control device mainly composed of, for example, a microcomputer. In particular, the controller 6 in the embodiment of the present invention mainly controls the operations of the driving power source 1 (engine 7) and the automatic transmission 3 respectively. Various data detected or calculated by the above detection unit 5 are input to the controller 6. The controller 6 performs calculations using the input various data and the data and calculation formulas etc. stored in advance. Then, the controller 6 outputs a control command signal based on the calculation result, and is configured to control the operations of the driving power source 1 (engine 7) and the automatic transmission 3 etc. as described above. Although FIG. 1 shows an example in which one controller 6 is provided, a plurality of controllers 6 may be provided for each device or equipment to be controlled, or for each control content.

[0021] As described above, the vehicle Ve in the embodiment of the present invention includes an automatic transmission 3 operated by a shift device 4. For example, when parking the vehicle Ve in a predetermined space, or during a direction change or a switching operation, a so-called garage shift that repeats forward and reverse is performed. As described above, in a vehicle Ve equipped with the automatic transmission 3 as described above, or a "vehicle" equipped with a "forward and reverse switching mechanism" in a "belt-type continuously variable transmission", during a garage shift, in order to protect the friction materials of the clutches and brakes in the automatic transmission 3 and the "forward and reverse switching mechanism", torque limit control for limiting the transmission torque transmitted by the automatic transmission 3 and the "forward and reverse switching mechanism" is executed. For example, like the throttle closing control in the vehicle control device described in Patent Document 1 above, by limiting the output torque of the engine 7, the torque input to the automatic transmission 3, that is, the transmission torque transmitted by the automatic transmission 3 is limited. Also, for example, by restricting the shift stages that can be set in the automatic transmission 3, or suppressing the hydraulic pressure for performing the shift control of the automatic transmission 3, etc., by providing restrictions or upper limits on the shift operation of the automatic transmission 3, the transmission torque transmitted by the automatic transmission 3 is limited. Thereby, even in a situation where the rotational speed difference between the friction materials of the clutches and brakes of the automatic transmission 3 is likely to increase due to the garage shift being performed, the load applied to such clutches and brakes can be suppressed, and overheating and burning of the friction materials can be prevented. That is, the automatic transmission 3 can be protected.

[0022] Incidentally, when the vehicle Ve travels on a muddy road, sandy ground, or a rough road with severe unevenness and the drive wheels 2 slip, causing the vehicle Ve to get stuck, for example, an operation called "rocking out" may be performed to rock the vehicle Ve back and forth to escape from the stuck state by repeating forward and reverse movements. That is, it is assumed that the above-described garage shift is performed in a situation where the drive wheels 2 are slipping. In such a situation, in the conventional control technology as described above, even when the drive wheels 2 are slipping, the torque limit control is executed when the garage shift is performed, and the transmission torque of the automatic transmission 3 is restricted. As a result, although a large driving force is required to escape from the stuck state, the necessary driving force cannot be obtained, and there is a possibility that the running performance of the vehicle Ve may deteriorate.

[0023] Also, as described above, when the garage shift is performed in a state where the drive wheels 2 are slipping, particularly when the drive wheels 2 are slipping in the reverse driving position (R range), a gear stage higher than the lowest gear stage (for example, the first gear stage, starting gear stage, etc.) (for example, the second gear stage, third gear stage, etc.) may be formed, and it may become impossible to obtain the necessary driving force. Usually, the vehicle speed is detected always assuming a forward state without distinguishing between forward and reverse. At the same time, the gear shift in the automatic transmission 3 is performed based on the vehicle speed and the accelerator opening. For example, the gear stage of the automatic transmission 3 is formed based on a shift diagram or a shift map that defines a shift line for determining the shift to each gear stage on a diagram showing the relationship between the vehicle speed and the accelerator opening. Therefore, in the conventional control, in a state where the drive wheels 2 are slipping in the reverse driving position (R range) as described above, even if the actual vehicle speed is 0, it may be determined that a predetermined vehicle speed is output from the wheel speed of the slipping drive wheels 2, and a high-speed gear stage corresponding to that vehicle speed may be formed. Therefore, when the grip of the drive wheels 2 is restored from a state where the drive wheels 2 are slipping and such a high-speed gear stage is formed, there is a possibility that the necessary large driving force cannot be obtained.

[0024] Therefore, even when a garage shift is performed while the drive wheels 2 are slipping, the vehicle control device according to the embodiment of the present invention generates an appropriate driving force so that the vehicle Ve can exhibit its original running performance. For example, it is configured to execute the control shown in the flowchart of FIG. 2 below.

[0025] In the flowchart of FIG. 2, first, in step S1, it is determined whether or not the tire is in a slip state. Specifically, it is determined whether or not slip has occurred in the drive wheels 2. For example, by comparing the detected value of the wheel speed sensor 5a with the vehicle speed calculated from the detected value of the acceleration sensor, it is possible to determine the presence or absence of slip in the drive wheels 2.

[0026] If it is negatively determined in this step S1 because no slip has occurred in the drive wheels 2, that is, the tire is not in a slip state, the routine shown in the flowchart of FIG. 2 is terminated once without executing the subsequent control.

[0027] On the other hand, if it is positively determined in step S1 because slip has occurred in the drive wheels 2, that is, the tire is in a slip state, the process proceeds to step S2.

[0028] In step S2, it is determined whether or not a shift operation in which the shift position is repeatedly switched between the forward driving position (D range) and the reverse driving position (R range), that is, a garage shift, has been performed. In short, in this step S2, it is determined whether or not a garage shift has been performed in a situation where the drive wheels 2 are slipping.

[0029] If it is negatively determined in this step S2 because the garage shift between the D range and the R range has not been performed, the routine shown in the flowchart of FIG. 2 is terminated once without executing the subsequent control.

[0030] On the other hand, if a garage shift is performed between the D range and the R range, that is, if the garage shift is performed in a situation where the drive wheels 2 are slipping, and it is affirmatively determined in step S2, the process proceeds to steps S3, S4, and S5, and the restriction on the transmission torque by the torque restriction control is released or relaxed.

[0031] As described above, in the vehicle in the embodiment of the present invention, when a garage shift is performed, for the purpose of protecting the automatic transmission 3, torque restriction control for restricting the transmission torque transmitted by the automatic transmission 3 is executed. Specifically, in the torque restriction control, (1) When the vehicle speed (the vehicle speed during forward travel and the vehicle speed during reverse travel) is an extremely low vehicle speed (for example, in the range of about 0 km / h to 10 km / h), the output torque of the engine 7 is restricted for a predetermined period (for example, about several seconds) (for example, a predetermined upper limit lower than normal is set for the output torque of the engine 7, and the transmission torque of the automatic transmission 3 is reduced), (2) When the vehicle speed is higher than the extremely low vehicle speed range, the output torque of the engine 7 is set to 0 for a predetermined period (for example, about several seconds), or the automatic transmission 3 is set to neutral, and the transmission torque of the automatic transmission 3 is set to 0, (3) When the vehicle speed is higher than the extremely low vehicle speed range, the hydraulic control for the automatic transmission 3 is restricted (for example, the control hydraulic pressure for the shift control that operates the clutch and the brake is suppressed to a hydraulic pressure level lower than normal, and the shift operation or shift speed of the automatic transmission 3 is suppressed), (4) When the vehicle speed is higher than the extremely low vehicle speed range, the setting of the reverse travel position (R range) in the automatic transmission 3 is prohibited, or the shift from the reverse travel position (R range) being set to the forward travel position (D range) or other shift positions is prohibited (the shift operation of the automatic transmission 3 is restricted), By such means, the transmission torque of the automatic transmission 3 is restricted.

[0032] For the torque limit control as described above, in the vehicle control device according to an embodiment of the present invention, when a garage shift is performed while the drive wheel 2 is slipping, in each of the following steps S3, S4, and S5, the restriction on the transmission torque by the torque limit control is released, or the restriction on the transmission torque by the torque limit control is invalidated. Or, the restriction on the transmission torque by the torque limit control is relaxed.

[0033] In step S3, the switching of the hydraulic control of the automatic transmission 3 is executed. Specifically, the control hydraulic pressure for the shift control that operates the clutch and brake of the automatic transmission 3 is switched to a hydraulic pressure level that is higher than the hydraulic pressure level suppressed by the torque limit control and lower than the normal hydraulic pressure level at which the torque limit control is not executed. That is, the restriction on the transmission torque by the torque limit control is relaxed. Or, the restriction on the hydraulic control for the automatic transmission 3 by the torque limit control is released or invalidated, and the control hydraulic pressure for the shift control is switched to the normal hydraulic pressure level at which the torque limit control is not executed. That is, the restriction on the transmission torque by the torque limit control is released. Or, the restriction on the transmission torque by the torque limit control is invalidated. Note that the hydraulic pressure level of the hydraulic control switched in this step S3 may be changed according to, for example, the vehicle speed or the state of the vehicle Ve.

[0034] In step S4, the switching of the torque control of the engine 7 is executed. Specifically, the output torque of the engine 7 transmitted to the automatic transmission 3 is switched to an output torque that is higher than the torque level suppressed by the torque control limit control and lower than the normal torque level at which the torque control limit control is not executed. That is, the restriction of the transmission torque by the torque control limit control is relaxed. Or, the restriction on the output torque of the engine 7 by the torque control limit control is released or invalidated, and the output torque of the engine 7 is switched to the normal torque level at which the torque control limit control is not executed. That is, the restriction of the transmission torque by the torque control limit control is released. Or, the restriction of the transmission torque by the torque control limit control is invalidated. Note that the torque level of the output torque of the engine 7 switched in this step S3 may be changed according to, for example, the vehicle speed or the state of the vehicle Ve.

[0035] In step S5, the switching of the determined gear stage for the automatic transmission 3 is executed. Specifically, the restrictions or prohibitions on the shifting operation of the automatic transmission 3 are released or relaxed. For example, even when the vehicle speed is higher than the extremely low vehicle speed range, the setting of the reverse travel position (R range) in the automatic transmission 3 is permitted. Or, a shift from the state where the reverse travel position (R range) is set to the forward travel position (D range) or other shift positions is permitted. In that case, for example, a predetermined gear stage is selected based on the normal shift line at which the torque control limit control is not executed.

[0036] Furthermore, in this step S5, when the reverse travel position (R range) is set, that is, when the drive wheels 2 are slipping in the reverse travel position (R range), it is made possible to select an arbitrary gear stage that is not necessarily based on the gear shift line. As described above, in the conventional control, when the drive wheels 2 are slipping in the reverse travel position (R range), if the gear stage is selected according to the normal gear shift line, even if the vehicle speed is actually 0, a high-speed gear stage such as the second gear stage or the third gear stage may be selected, and it may not be possible to obtain the necessary large driving force. On the other hand, in the control according to the embodiment of the present invention, as described above, since the selection of the gear stage can be arbitrarily performed, even if a high-speed gear stage is determined by the normal gear shift line, a lower-speed gear stage such as the first gear stage or the starting gear stage can be selected. Therefore, when the grip of the slipping drive wheels 2 is restored, a large driving force according to the situation can be obtained.

[0037] Therefore, also in this step S5, ultimately, the restriction of the transmission torque by the torque restriction control is relaxed. Or, the restriction of the transmission torque by the torque restriction control is released. Or, the restriction of the transmission torque by the torque restriction control is invalidated.

[0038] Note that the control in each of the above steps S3, S4, and S5 may be executed, for example, simultaneously or in parallel. Or, the order may be appropriately changed and executed.

[0039] Then, in step S6, it is determined whether or not the synchronization determination for the automatic transmission 3 is completed. Specifically, it is determined whether or not the rotational speed difference between the friction materials in the clutch and the brake of the automatic transmission 3 has become 0 or has become equal to or less than a predetermined value. That is, in this step S6, as described above, the garage shift is performed in a state where the restriction of the transmission torque of the automatic transmission 3 by the torque restriction control is released or relaxed, and it is determined whether or not the shift control of the automatic transmission 3 by the garage shift is completed.

[0040] If the synchronization determination for the automatic transmission 3 has not been completed yet and thus a negative determination is made in this step S6, the control of this step S6 is executed again. That is, the control of step S6 is repeated until the synchronization determination for the automatic transmission 3 is completed.

[0041] Therefore, if a positive determination is made in step S6 because the synchronization determination for the automatic transmission 3 is completed, that is, the garage shift has ended under the condition that the restriction on the transmission torque of the automatic transmission 3 by the torque restriction control has been released or relaxed as described above, the routine shown in the flowchart of FIG. 2 is temporarily terminated.

[0042] As described above, in the vehicle control device according to the embodiment of the present invention, when a garage shift is performed as in the prior art, torque restriction control for restricting the transmission torque of the automatic transmission 3 is executed to protect the clutch, brake, etc. of the automatic transmission 3. For example, by restricting the magnitude of the output torque of the engine 7, the transmission torque of the automatic transmission 3 is restricted. Alternatively, by restricting the shift operation of the automatic transmission 3, the transmission torque of the automatic transmission 3 is restricted. And in the vehicle control device according to the embodiment of the present invention, when the above-described garage shift is performed in a situation where slip occurs in the drive wheels 2 of the vehicle Ve, the restriction on the transmission torque of the automatic transmission 3 by the torque restriction control is released. Alternatively, the restriction on the transmission torque of the automatic transmission 3 by the torque restriction control is relaxed. For example, by releasing the restriction on the torque level of the output torque of the engine 7, the restriction on the transmission torque of the automatic transmission 3 is released. Alternatively, by relaxing the restriction on the torque level of the output torque of the engine 7, the restriction on the transmission torque of the automatic transmission 3 is relaxed. Therefore, for example, when a garage shift is performed to escape from a situation where the drive wheels 2 slip on a muddy road, sandy ground, or rough road and the vehicle Ve gets stuck, the restriction on the transmission torque of the automatic transmission 3 by the torque restriction control can be released or relaxed to generate a large driving force necessary to escape from the stuck state.

[0043] Therefore, according to the vehicle control device in the embodiment of the present invention, even when a garage shift is performed while the drive wheels 2 are slipping, it is possible to avoid a decrease in the running performance of the vehicle Ve and allow the vehicle Ve to exhibit its original running performance.

Explanation of Reference Numerals

[0044] 1 Driving force source 2 Drive wheels (rear wheels) 3 Automatic transmission (AT) 3a Input shaft (of the automatic transmission) 3b Output shaft (of the automatic transmission) 4 Shift device 5 Detection unit 5a Wheel speed sensor (of the detection unit) 5b Engine speed sensor (of the detection unit) 5c Input shaft speed sensor (of the detection unit) 5d Output shaft speed sensor (of the detection unit) 5e Hydraulic pressure sensor (of the detection unit) 5f Shift position sensor (of the detection unit) 6 Controller (ECU) 7 Engine (ENG; driving force source) 7a Output shaft (of the engine) 8 Propeller shaft 9 Differential gear 10 Drive shaft Ve Vehicle

Claims

【Claim 1】 A vehicle control device including a driving force source that outputs torque for driving a driving wheel, a transmission that changes the rotational speed of the output shaft of the driving force source and transmits the torque between the driving force source and the driving wheel, and that can be manually switched and set to a forward travel position and a reverse travel position by a driver, and executes torque limit control for limiting the transmission torque transmitted by the transmission when a garage shift in which a switching operation between the forward travel position and the reverse travel position is repeated is performed. The vehicle control device includes a controller that controls the driving force source and the transmission, respectively. The controller When the garage shift is performed in a state where slip of the driving wheel occurs, releases the restriction of the transmission torque by the torque limit control, or relaxes the restriction of the transmission torque by the torque limit control. A vehicle control device characterized by the above.

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