Vehicle control device

Abstract

To decrease the response delay of transmission control, and to execute the gear change of an automatic transmission at a proper timing.SOLUTION: A vehicle control device is equipped with an automatic transmission with stages performing gear change by hydraulically controlling a friction engagement element, and determines the execution of the gear change on the basis of a transmission threshold. An drive state of a vehicle exceeds the transmission threshold to execute the gear change. A transmission preparation threshold different from the transmission threshold is provided, and before the execution of the transmission, the drive state exceeds the transmission preparation threshold to execute transmission preparation control which supplies engagement preparation hydraulic pressure lower than the engagement hydraulic pressure while keeping a releasing state with respect to the friction engagement element in the releasing state, or lowers the engagement hydraulic pressure till releasing preparation hydraulic pressure that is lower than the engagement hydraulic pressure and higher than the releasing hydraulic pressure while keeping the engagement state with respect to the friction engagement element in the engaging state (a step S3).SELECTED DRAWING: Figure 5

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 performs gear shift control of an automatic transmission that can change gears by switching between gear stages and set multiple gear stages. [Background technology]

[0002] Patent Document 1 describes a hydraulic control device for an automatic transmission that aims to suppress shift shock when a gear change is performed using a so-called power-off downshift. The hydraulic control device for an automatic transmission described in Patent Document 1 is configured to estimate, from the vehicle deceleration, the possibility that a request for a gear change to a lower gear (next gear) will occur during a power-off downshift gear change operation, and to start supplying pre-engagement hydraulic pressure to the friction engagement element that will be engaged at the next gear if it estimates that a request for a gear change to the next gear will occur during the gear change.

[0003] Furthermore, Patent Document 2 describes a gear shift control device for an automatic transmission that selects either a gear shift pattern in which the shift vehicle speed is set low or a gear shift pattern in which the shift vehicle speed is set high according to the accelerator operation speed (engine load change rate) with the aim of enabling gear shift control that reflects the driver's intentions. The gear shift control device for an automatic transmission described in Patent Document 2 is configured to, when the accelerator pedal is depressed slowly and the throttle opening is gradually increasing, suspend judgment on selection of a gear shift pattern until the increase in throttle opening from the point at which the throttle opening starts to increase (i.e., the point at which the accelerator pedal begins to be depressed) exceeds a predetermined amount, and only when the predetermined amount is exceeded does it calculate the throttle opening change rate for judging selection of a gear shift pattern and execute judgment on selection of a gear shift pattern based on the calculated value.

[0004] Patent Document 3 describes a shift control device for an automatic transmission that controls gear shifting of the transmission by selectively controlling the engagement of multiple friction engagement elements. The shift control device for an automatic transmission described in Patent Document 3 calculates the amount of heat stored for each friction engagement element based on the amount of heat generated and the amount of heat dissipated by the friction engagement elements that engage during gear shifting, and is configured to set the timing of upshifting to a gear using at least the friction engagement element with the amount of heat stored equal to or greater than the set value to be earlier than when the amount of heat stored is equal to or less than the set value.

[0005] Furthermore, Patent Document 4 describes a shift control device for an automatic transmission that can switch between an automatic shift mode in which a shift operation is performed by determining the gear to be set based on the driving state, and a manual shift mode in which a shift operation is performed in accordance with a manual operation by the driver. The shift control device for an automatic transmission described in Patent Document 4 is configured so that if a switch operation to the other shift mode occurs while a shift operation in either the automatic shift mode or the manual shift mode is being performed, the shift operation in the other shift mode starts after the shift operation in the shift mode before the switch operation has finished. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] Japanese Patent Application Laid-Open No. 2008-223939 [Patent Document 2] Japanese Patent Application Publication No. 6-129529 [Patent Document 3] Japanese Patent Application Laid-Open No. 2005-98431 [Patent Document 4] Japanese Patent Application Laid-Open No. 2000-2325 Summary of the Invention [Problem to be solved by the invention]

[0007] As described above, in the hydraulic control device for an automatic transmission described in Patent Document 1, if a request to shift to the next gear is likely to occur during a gear shift, the friction engagement elements (clutches and brakes) that should be engaged in the next gear are initiated to engage. This shortens the time it takes for the next gear to be established after a request to shift to the next gear. Therefore, the hydraulic control device for an automatic transmission described in Patent Document 1 is capable of achieving an appropriate gear according to the vehicle speed without delaying the gear shift, even when multiple downshifts are performed under conditions of relatively high vehicle deceleration, thereby suppressing shift shock. However, even in the hydraulic control device for an automatic transmission described in Patent Document 1, normal gear shift control is performed using a gear shift map that sets shift lines (upshift lines and downshift lines), as in the conventional case. As the vehicle's operating conditions, based on the vehicle speed and accelerator pedal position, change across the shift lines on the shift map, a shift determination is made, the target gear is changed, and a hydraulic pressure command signal is output to set the new (changed) target gear. Then, hydraulic pressure based on the hydraulic pressure command signal is supplied, and the clutches and brakes of the automatic transmission are actuated, thereby actually shifting gears in the automatic transmission. Therefore, due to the responsiveness of the hydraulic pressure control as described above, a response delay in the shift control inevitably occurs.

[0008] Furthermore, as with the automatic transmission shift control device described in Patent Document 2, by configuring the device to appropriately select one of multiple shift patterns, it is possible to perform a shift at an appropriate speed depending on the accelerator pedal operation speed. For example, when the accelerator pedal is operated faster than normal, a high-vehicle speed shift pattern is set to speed up the shift decision, thereby accelerating the shift output (control command) compared to normal shift operations. This allows the timing of the shift to be advanced in response to a sudden accelerator pedal operation. However, while the above-described control advances the timing of the shift, it does not shorten the duration of the series of shift operations (shift time). Therefore, it is unable to eliminate the response delay of the shift control described above. Furthermore, since the automatic transmission shift control device described in Patent Document 2 changes the timing of the shift output depending on the accelerator pedal operation speed, there is a possibility that the shift will be performed against the driver's intention if the driver's accelerator pedal operation is inconsistent.

[0009] This invention was devised with an eye on the above-mentioned technical problems, and aims to provide a vehicle control device that can reduce the response delay of gear shift control and perform gear shifts in an automatic transmission at appropriate timing. [Means for solving the problem]

[0010] In order to achieve the above object, the present invention provides a vehicle control device that is equipped with an automatic transmission that is capable of shifting by hydraulically controlling the engaged and disengaged states of frictional engagement elements to switch between and set a plurality of gear stages each having a different gear ratio, and that determines whether to execute the gear change using a shift threshold that defines the relationship between a required driving force and a vehicle speed (or the number of revolutions of the output shaft of the automatic transmission) as a criterion for determination, and that performs hydraulic control to supply an engagement hydraulic pressure to the frictional engagement elements in a disengaged state to bring the frictional engagement elements in the disengaged state into an engaged state, or to reduce the engagement hydraulic pressure to the frictional engagement elements in an engaged state to a release hydraulic pressure at which the frictional engagement elements in the engaged state are released, and selectively sets one of the gear stages. The present invention is characterized in that the controller executes the shift and switches the gear when the operating state based on the required driving force and the vehicle speed exceeds the shift threshold, and has a shift preparation threshold different from the shift threshold, and executes shift preparation control such that, prior to the execution of the shift, when the operating state based on the required driving force and the vehicle speed exceeds the shift preparation threshold, an engagement preparation oil pressure lower than the engagement oil pressure is supplied to the friction engagement element in the released state while maintaining the released state, or the engagement oil pressure is reduced to a release preparation oil pressure lower than the engagement oil pressure and higher than the release oil pressure while maintaining the engaged state, for the friction engagement element in the engaged state.

[0011] The controller in this invention has, as the shift thresholds, an upshift threshold for determining whether to perform an upshift to change gear to a gear having a smaller gear ratio than the currently set gear, and a downshift threshold for determining whether to perform a downshift to change gear to a gear having a larger gear ratio than the currently set gear. The controller executes the upshift when the driving state changes across the upshift threshold in a direction in which the required driving force becomes lower and the vehicle speed becomes higher, and executes the downshift when the driving state changes across the downshift threshold in a direction in which the required driving force becomes higher and the vehicle speed becomes lower. The controller also has, as the shift preparation thresholds, an upshift threshold for determining whether to perform an upshift to change gear to a gear having a smaller gear ratio than the currently set gear, and a downshift threshold for determining whether to perform a downshift to change gear to a gear having a larger gear ratio than the currently set gear. and an upshift preparation threshold that is set at a lower vehicle speed and defines a relationship between the required driving force and the vehicle speed in parallel with the upshift threshold, and a downshift preparation threshold that is set near the downshift threshold, where the required driving force is lower than the downshift threshold and the vehicle speed is higher, and defines a relationship between the required driving force and the vehicle speed in parallel with the downshift threshold. When the driving state changes across the upshift preparation threshold in a direction such that the required driving force becomes lower and the vehicle speed becomes higher, the gearshift preparation control is executed prior to execution of the upshift, and when the driving state changes across the downshift preparation threshold in a direction such that the required driving force becomes higher and the vehicle speed becomes lower, the gearshift preparation control is executed prior to execution of the downshift.

[0012] Furthermore, the controller in this invention may have a predicted shift preparation threshold, which is the shift preparation threshold for determining whether to execute the shift preparation control, and which specifies a reference value for at least one of an acceleration request amount based on a driving operation by the driver and a deceleration request amount based on the driving operation, and may be configured to acquire at least one of the actual acceleration request amount and the actual deceleration request amount, and to execute the shift preparation control when the acquired acceleration request amount or deceleration request amount exceeds (exceeds) the predicted shift preparation threshold prior to executing the shift.

[0013] Further, the controller in this invention has, as the shift thresholds, an upshift threshold for determining execution of an upshift to perform the shift to the gear stage having a smaller gear ratio than the currently set gear stage, and a downshift threshold for determining execution of a downshift to perform the shift to the gear stage having a larger gear ratio than the currently set gear stage, and executes the upshift when the driving state changes across the upshift threshold in a direction in which the required driving force becomes lower and the vehicle speed becomes higher, and executes the downshift when the driving state changes across the downshift threshold in a direction in which the required driving force becomes higher and the vehicle speed becomes lower. When the actual amount of required acceleration becomes larger than the predicted upshift preparation threshold, the downshift is executed, and the predicted shift preparation thresholds include a predicted upshift preparation threshold for predicting the execution of the upshift and determining whether to execute the shift preparation control, and a predicted downshift preparation threshold for predicting the execution of the downshift and determining whether to execute the shift preparation control. The system may be configured so that when the actual amount of required acceleration becomes larger than the predicted upshift preparation threshold, the shift preparation control is executed prior to the upshift, and when the actual amount of required deceleration becomes larger than the predicted downshift preparation threshold, the shift preparation control is executed prior to the downshift.

[0014] Furthermore, the automatic transmission of the present invention may be configured such that, when a manual shift mode is selected, manual shifting is possible, in which the shift is performed in response to a shift operation by the driver, and the controller of the present invention has a manual shift preparation threshold that is the shift preparation threshold for determining whether to execute the shift preparation control in the manual shift mode, and that defines a reference value for at least one of an acceleration request amount based on a driving operation of the driver and a deceleration request amount based on the driving operation, and acquires at least one of an actual acceleration request amount and an actual deceleration request amount, and, when the manual shift mode is selected, prior to the execution of the manual shift, executes the shift preparation control when the acquired acceleration request amount or deceleration request amount exceeds (exceeds) the manual shift preparation threshold.

[0015] Furthermore, the controller in this invention may have, as the manual shift preparation thresholds, a manual upshift preparation threshold for determining whether to execute the shift preparation control by predicting that the driver will perform an upshift operation to change the gear to a gear having a smaller gear ratio than the currently set gear, and a manual downshift preparation threshold for determining whether to execute the shift preparation control by predicting that the driver will perform a downshift operation to change the gear to a gear having a larger gear ratio than the currently set gear. With the manual shift mode selected, the controller may be configured to perform the upshift or the downshift in accordance with the shift operation, and to execute the shift preparation control prior to the upshift when the actual required acceleration amount becomes larger than the manual upshift preparation threshold, and to execute the shift preparation control prior to the downshift when the actual required deceleration amount becomes larger than the manual downshift preparation threshold.

[0016] Furthermore, when executing the shift preparation control, the controller of the present invention may be configured to obtain at least either the duration from the point at which execution of the shift preparation control was started or the amount of heat absorption by the friction engagement element during the duration, and to terminate the shift preparation control when at least either the duration exceeds a predetermined reference time or the amount of heat absorption exceeds a predetermined reference heat amount. [Effects of the Invention]

[0017] The vehicle control device of the present invention controls a vehicle equipped with an automatic transmission capable of setting multiple gears, and performs gear shift control of the automatic transmission. The automatic transmission hydraulically controls frictional engagement elements, such as clutches and brakes, to switch gears and set a predetermined gear. Similar to conventional automatic transmissions, gear shifting (gear shift control), which hydraulically controls frictional engagement elements to switch gears, is performed when, for example, a driving state based on a required driving force determined by factors such as accelerator position and throttle valve opening, and vehicle speed or output shaft rotation speed (of the automatic transmission), or a driving point indicating such a driving state, exceeds or crosses a gear shift threshold. The gear shift threshold is, for example, a gear shift line on a gear shift map or a gear shift diagram, and is a criterion for determining whether to perform a gear shift that defines the relationship between the required driving force and vehicle speed (output shaft rotation speed).

[0018] In the shift control of an automatic transmission as described above, an unavoidable delay in response to the control occurs due to, for example, the response time of hydraulic pressure or electrical signals, and the torsion or rotational inertia of rotating elements. Therefore, in conventional shift control of an automatic transmission, the shift line (shift threshold) as described above is set in advance to anticipate the delay in response to the control. In contrast, the vehicle control device of the present invention provides a shift preparation threshold different from the shift threshold as well as the shift threshold. The shift preparation threshold is set, for example, on a shift map or shift line diagram, near the shift threshold (shift line) and at a value parallel to the shift threshold. The shift preparation threshold is executed when the driving state exceeds (crosses) the shift preparation threshold before the shift threshold. In other words, the shift preparation control of the present invention is executed prior to the execution of a shift in the automatic transmission. In order to reduce the response delay of the control described above, the gear shift preparation control performs hydraulic control of the friction engagement elements that will be activated during the subsequent gear shift, and keeps the engaged and disengaged states of the friction engagement elements in a predetermined gear shift preparation state or gear shift standby state. By executing the gear shift preparation control, engagement preparation hydraulic pressure is supplied to the friction engagement elements in the released state. Furthermore, engagement hydraulic pressure is discharged from the friction engagement elements in the engaged state. Therefore, the released friction engagement elements maintain their released state, i.e., do not enter the engaged state, but slightly move toward the engagement side to enter the gear shift preparation state. Furthermore, the engaged friction engagement elements maintain their engaged state, i.e., do not enter the disengaged state, but slightly move toward the disengagement side to enter the gear shift preparation state.

[0019] For example, the shift preparation thresholds are configured with an upshift preparation threshold that is set near the upshift threshold (upshift line) and at a higher required driving force than the upshift threshold and at a lower vehicle speed, and a downshift preparation threshold that is set near the downshift threshold (downshift line) and at a lower required driving force than the downshift threshold and at a higher vehicle speed. Therefore, in the vehicle control device of the present invention, the vehicle operating state crosses the upshift preparation threshold before crossing the upshift threshold, thereby executing the shift preparation control. That is, the shift preparation control for the upshift is executed prior to the execution of the upshift. Similarly, in the vehicle control device of the present invention, the vehicle operating state crosses the downshift preparation threshold before crossing the downshift threshold, thereby executing the shift preparation control. That is, the shift preparation control for the downshift is executed prior to the execution of the downshift.

[0020] Furthermore, in the vehicle control device of the present invention, as described above, a predicted shift preparation threshold is provided as the shift preparation threshold for determining whether to execute the shift preparation control. The predicted shift preparation threshold defines at least one reference value of a required acceleration amount, such as an accelerator operation amount (accelerator opening), a throttle valve opening, or a fuel injection amount, or a required deceleration amount, such as a brake operation amount, stroke, pedal force, or master cylinder pressure. The shift preparation control is executed when the actual required acceleration amount or the actual required deceleration amount based on the driver's driving operation exceeds (exceeds) the predicted shift preparation threshold. In other words, the shift preparation control is executed when the actual required acceleration amount or the actual required deceleration amount exceeds the predicted shift preparation threshold and it is predicted that a shift of the automatic transmission will be executed immediately thereafter.

[0021] For example, the predicted gearshift preparation thresholds are configured with a predicted upshift preparation threshold that is different from the upshift threshold (upshift line) and set to a value lower than the accelerator operation amount corresponding to the upshift threshold, and a predicted downshift preparation threshold that is different from the downshift threshold (downshift line) and set to a value lower than the brake operation amount corresponding to the downshift threshold. Therefore, in the vehicle control device of the present invention, when the accelerator operation amount exceeds the predicted upshift preparation threshold and an upshift is predicted to be performed immediately thereafter (high probability of an upshift being performed), gearshift preparation control for the upshift is executed prior to the execution of the downshift. Alternatively, in the vehicle control device of the present invention, when the brake operation amount exceeds the predicted upshift preparation threshold and a downshift is predicted to be performed immediately thereafter (high probability of a downshift being performed), gearshift preparation control for the downshift is executed prior to the execution of the downshift.

[0022] The vehicle control device of the present invention is particularly designed for a situation in which the driver manually changes gears in the automatic transmission (manual shift mode). The manual shift preparation threshold, which defines at least one reference value for the acceleration demand, such as the accelerator operation amount (accelerator opening), throttle valve opening, or fuel injection amount, or the deceleration demand, such as the brake operation amount, stroke, pedal force, or master cylinder pressure, is used as the shift preparation threshold for determining whether to execute the shift preparation control. When the manual shift mode of the automatic transmission is selected, the shift preparation control is executed when the actual acceleration demand or the actual deceleration demand based on the driver's driving operation exceeds the manual shift preparation threshold. That is, the shift preparation control is executed when the actual acceleration demand or the actual deceleration demand exceeds the manual shift preparation threshold and the driver's intention to manually shift gears in the automatic transmission is predicted immediately after the actual acceleration demand or the actual deceleration demand exceeds the manual shift preparation threshold.

[0023] For example, the manual shift preparation threshold includes a manual upshift preparation threshold that is different from the upshift threshold (upshift line) and set to a value lower than the accelerator operation amount corresponding to the upshift threshold, and a manual downshift preparation threshold that is different from the downshift threshold (downshift line) and set to a value lower than the brake operation amount corresponding to the downshift threshold. Therefore, in the vehicle control device of the present invention, when the accelerator operation amount exceeds the manual upshift preparation threshold in a manual shift mode of the automatic transmission and a manual upshift is predicted to be performed immediately thereafter (i.e., a manual upshift is highly likely), shift preparation control for the upshift is executed prior to the execution of the upshift. Alternatively, in the vehicle control device of the present invention, when the brake operation amount exceeds the manual downshift preparation threshold and a manual downshift is predicted to be performed immediately thereafter (i.e., a manual downshift is highly likely), shift preparation control for the downshift is executed prior to the execution of the downshift.

[0024] Therefore, according to the vehicle control device of the present invention, a shift preparation threshold as described above is set in addition to the normal shift threshold (shift line), and shift preparation control is executed based on the shift preparation threshold. By executing the shift preparation control of the present invention, the engagement hydraulic pressure of the frictional engagement element that is engaged or disengaged to achieve the upshift or downshift is preliminarily controlled prior to the actual execution of the upshift or downshift. That is, the engagement hydraulic pressure is increased or decreased within a range in which the frictional engagement element does not switch between engaged and disengaged states, or within a range in which the actual shift does not occur, to bring the frictional engagement element into a shift preparation state. By placing the frictional engagement element in a shift preparation state in advance of the actual shift, it is possible to reduce the hydraulic response delay, which is a major factor in the response delay of the shift control. Therefore, the shift threshold, which was previously set to anticipate a relatively large response delay, can be set to anticipate only the minimum response delay reduced by the shift preparation control. Therefore, the automatic transmission can shift at an appropriate timing as originally intended, or close to the originally intended timing.

[0025] The above-described shift preparation control is terminated, for example, when the duration of the shift preparation control exceeds a predetermined reference time, or when the amount of heat absorbed (or generated) by the frictional engagement element during the duration of the shift preparation control exceeds a predetermined reference heat amount. For example, if the duration of the shift preparation control is extended due to the vehicle operating conditions while allowing the frictional engagement element to slip during the shift preparation control, the execution of the shift preparation control can be terminated. This prevents an increase in loss and a decrease in the vehicle's energy efficiency caused by the frictional engagement element continuing to slip for a long period of time during the shift preparation control. Furthermore, a decrease in the durability of the frictional engagement element can be prevented. [Brief explanation of the drawings]

[0026] [Figure 1] 1 is a diagram for explaining a vehicle to be controlled by a vehicle control device of the present invention, and is a diagram schematically showing an example of the configuration and control system of the vehicle. FIG. [Figure 2] 3 is a diagram showing an image of a shift threshold (shift line) and a shift preparation threshold (shift preparation line) used to determine whether or not the vehicle control device of the present invention should execute shift control and shift preparation control; FIG. [Figure 3] FIG. 1 is a diagram for explaining a problem with conventional gear shift control, illustrating a situation in which a gear shift line that takes into account a response delay in hydraulic control does not coincide with the point at which the gear shift is actually desired to start. [Figure 4] FIG. 1 is a diagram for explaining a problem with conventional gear shift control, illustrating an image of a situation in which a gear shift is performed against the driver's intention when the driver's driving operation is unstable. [Figure 5] 3 is a flowchart illustrating an example of control executed by the vehicle control device of the present invention. [Figure 6]10 is a time chart showing the transition of the engagement oil pressure of the engagement-side friction engagement element, illustrating the effect of the shift preparation control executed by the vehicle control device of the present invention; FIG. [Figure 7] 10 is a diagram for explaining the effect of the shift preparation control executed by the vehicle control device of the present invention, and is a time chart showing the transition of the engagement oil pressure (release oil pressure) of the friction engagement element on the release side. FIG. [Figure 8] 10 is a flowchart illustrating another example of control executed by the vehicle control device of the present invention. [Figure 9] 1 is a diagram showing an image of a predicted shift preparation threshold (predicted shift preparation line) and a manual shift preparation threshold (manual shift preparation line) used to determine whether the vehicle control device of the present invention should execute shift preparation control; DETAILED DESCRIPTION OF THE INVENTION

[0027] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The following embodiments of the present invention will be described with reference to the accompanying drawings. Note that the following embodiments are merely examples of specific embodiments of the present invention and are not intended to limit the scope of the present invention.

[0028] The vehicle controlled in the embodiment of the present invention is equipped with an automatic transmission capable of shifting gears and setting multiple gears. It may be a conventional engine vehicle equipped with an internal combustion engine as a driving force source. Alternatively, it may be a hybrid vehicle equipped with an engine and a motor as a driving force source. Furthermore, it may be an electric vehicle that uses a motor as its only driving force source and combines a stepped automatic transmission with the motor. The automatic transmission can set multiple gears with different gear ratios by hydraulically controlling friction engagement elements provided inside. For example, a stepped (stepped) automatic transmission is used, in which the power transmission state between multiple planetary gear mechanisms is hydraulically controlled by the operation of friction engagement elements. Alternatively, it may be an automatic transmission such as a dual clutch transmission (DCT) that uses two clutch systems and a constantly meshing gear mechanism. Alternatively, it may be a belt-type continuously variable transmission (CVT) equipped with an auxiliary transmission that switches between multiple gears (e.g., high and low gears). An example of the configuration (drive system and control system) of a vehicle equipped with such an automatic transmission is shown in FIG.

[0029] The vehicle Ve shown in FIG. 1 includes, as its main components, a driving force source 1, driving wheels 2, an automatic transmission (AT) 3, a friction engagement element 4 (of the automatic transmission 3), a detection unit 5, and a controller (ECU) 6.

[0030] The driving force source 1 outputs torque for driving the drive wheels 2, i.e., torque for generating driving force for the vehicle Ve. In the example shown in FIG. 1, the driving force source 1 is an engine (ENG) 7. The engine 7 is, for example, an internal combustion engine such as a gasoline engine or a diesel engine, and is configured to electrically control its operating state, such as adjusting its output and starting and stopping. In the case of a gasoline engine, the throttle valve opening, the fuel supply or injection amount, the ignition on / off, and the ignition timing are electrically controlled. In the case of a diesel engine, the fuel injection amount, the fuel injection timing, or the throttle valve opening (in an EGR system) are electrically controlled. Note that the driving force source 1 in the embodiment of the present invention may be, in addition to the engine 7 described above, a hybrid drive unit (not shown) equipped with the engine 7 and a motor (motor generator), for example. The vehicle control device in the embodiment of the present invention can also control a hybrid vehicle (not shown) that combines such a hybrid drive unit with an automatic transmission 3 (described later).

[0031] The drive wheels 2 are wheels that generate drive force for the vehicle Ve by transmitting the output torque of the drive power source 1. In the example shown in FIG. 1, the drive wheels 2 are rear wheels of the vehicle Ve, and are connected to an output shaft 3a of an automatic transmission 3 (described later) via a propeller shaft 8, a differential gear 9, and left and right drive shafts 10. That is, in the example shown in FIG. 1, the vehicle Ve is a rear-wheel drive vehicle in which the rear wheels are drive wheels 2 and drive force is generated by the rear wheels. Note that the vehicle Ve in the embodiment of the present invention may be a front-wheel drive vehicle (not shown) in which the front wheels are drive wheels 2 and drive force is generated by the front wheels. Alternatively, the vehicle Ve may be a four-wheel drive vehicle (not shown) in which the output torque of the drive power source 1 is distributed to the front and rear wheels by a transfer case (not shown), i.e., the front and rear wheels are drive wheels 2. Alternatively, the vehicle may be a four-wheel drive hybrid vehicle (not shown) in which either the front or rear wheels are driven by an engine 7 and the other of the front or rear wheels is driven by a motor.

[0032] The automatic transmission 3 is provided in a power transmission path 11 between the driving force source 1 and the drive wheels 2, and transmits the output torque of the driving force source 1 within the power transmission path 11. At the same time, the automatic transmission 3 changes the rotation speed of an output shaft (not shown) of the driving force source 1. In the example shown in FIG. 1 , the automatic transmission 3 is connected to the output side of the engine 7 via, for example, a torque converter or the like (not shown), and transmits the output torque of the engine 7 to the drive wheels 2 between the engine 7 and the drive wheels 2. The automatic transmission 3 is a power transmission device that can appropriately change the ratio of the rotation speed of the output shaft 3 a to the rotation speed of the input shaft (not shown), i.e., the gear ratio, and automatically controls the change of the gear ratio, i.e., the gear shift control. Specifically, the automatic transmission 3 is a conventional, commonly used vehicle transmission, for example, a stepped (multi-stage) "automatic transmission" that hydraulically controls the power transmission state between a plurality of planetary gear mechanisms (not shown). Alternatively, it may be a "dual clutch transmission" (DCT) as mentioned above, or a "belt-type continuously variable transmission" (CVT) equipped with a hydraulically controlled sub-transmission mechanism.

[0033] The automatic transmission 3 also includes a hydraulic control device (not shown) that hydraulically controls gear shifting operations such as changing gears (gear ratios), switching between forward and reverse gears, and setting the neutral state. Specifically, the hydraulic control device hydraulically controls the operation of friction engagement elements (or friction engagement mechanisms) 4 configured inside the automatic transmission 3. For example, the friction engagement elements 4 are "clutches" and "brakes" provided inside the automatic transmission 3, and the above-described gear shifting operations are performed by hydraulically controlling the engagement and release operations of these "clutches" and "brakes." The friction engagement elements 4 are engaged by supplying a predetermined engagement hydraulic pressure to the friction engagement elements 4 in a released state. The friction engagement elements 4 are also released by discharging the engagement hydraulic pressure from the friction engagement elements 4 in an engaged state. By executing such hydraulic control to supply and discharge the engagement hydraulic pressure, one of multiple gears with different gear ratios is selectively set.

[0034] As in the past, the automatic transmission 3 shifts gears using, for example, shift thresholds (shift lines referred to as upshift lines and downshift lines) set on a shift diagram or shift map. The shift thresholds (shift lines) are reference values ​​or thresholds that define the relationship between required driving force and vehicle speed on a shift diagram or shift map such as that shown in FIG. 2. The automatic transmission 3 determines whether to perform a shift using these shift thresholds as a determination criterion. In the example shown in FIG. 2, on the shift diagram or shift map in which the vertical axis represents the accelerator opening (required driving force) and the horizontal axis represents the output shaft rotation speed (or vehicle speed) of the automatic transmission 3, an upshift threshold (x → x+1 / Up shift line) is set as the shift threshold for an upshift from the xth gear to the (x+1)th gear, and a downshift threshold (x+1 → x / Down shift line) is set as the shift threshold for a downshift from the (x+1)th gear to the xth gear. When the operating state of the vehicle Ve, based on the vehicle speed (output shaft rotation speed) and accelerator opening (required driving force), changes across a shift threshold (shift line), a shift determination is made for the automatic transmission 3, the target gear position is changed, and a hydraulic pressure command signal is output to set the new (changed) gear position. Then, hydraulic pressure based on the hydraulic pressure command signal is supplied, and the "clutch" and "brake" of the automatic transmission 3 are actuated, thereby actually shifting gears in the automatic transmission 3.

[0035] Furthermore, in the shifting of the automatic transmission 3 according to the embodiment of the present invention, a shift preparation threshold is set in addition to the shift threshold (shift line). The shift preparation threshold is a reference value or threshold different from the shift threshold, and is set, for example, on a shift diagram or a shift map, in other words, a shift preparation line. In the example shown in FIG. 2 , an upshift preparation threshold (Up preparation line) is set on the shift diagram or shift map as a shift preparation threshold for an upshift from the xth gear to the (x+1)th gear, and a downshift preparation threshold (Down preparation line) is set as a shift preparation threshold for a downshift from the (x+1)th gear to the xth gear. The upshift preparation threshold is set in parallel with the upshift threshold near the upshift threshold, on the side where the required driving force (or accelerator pedal depression) is higher and the vehicle speed (or output shaft rotation speed) is lower than the upshift threshold, and defines the relationship between the required driving force (accelerator pedal depression) and the vehicle speed (output shaft rotation speed). Furthermore, the downshift preparation threshold is set in parallel with the downshift threshold near the downshift threshold, on the side where the required driving force (or accelerator pedal depression) is lower and the vehicle speed (or output shaft rotation speed) is higher than the downshift threshold, thereby defining the relationship between the required driving force (accelerator pedal depression) and the vehicle speed (output shaft rotation speed). Therefore, in the vehicle control device according to the embodiment of the present invention, the operating state of the vehicle Ve crosses the upshift preparation threshold before crossing the upshift threshold, thereby executing the gearshift preparation control. That is, prior to the execution of an upshift, the gearshift preparation control for the upshift is executed. Similarly, in the vehicle control device according to the embodiment of the present invention, the operating state of the vehicle Ve crosses the downshift preparation threshold before crossing the downshift threshold, thereby executing the gearshift preparation control. That is, prior to the execution of a downshift, the gearshift preparation control for the downshift is executed.

[0036] The shift preparation control is a control that performs hydraulic control of the friction engagement element 4 to be activated during a subsequent shift in advance, in order to reduce a response delay in the control of the shift of the automatic transmission 3, and keeps the engaged and disengaged states of the friction engagement element 4 in a predetermined shift preparation state or shift standby state. By executing such shift preparation control, an engagement preparation hydraulic pressure is supplied to the friction engagement element 4 in the released state. Furthermore, the engagement hydraulic pressure acting on the friction engagement element 4 in the engaged state is reduced to a release preparation hydraulic pressure. The engagement preparation hydraulic pressure is a target value of hydraulic pressure supplied to the friction engagement element 4 in the released state, and is lower than the engagement hydraulic pressure supplied when the friction engagement element 4 is engaged. Furthermore, the release preparation hydraulic pressure is a target value of hydraulic pressure to be reduced from the engaged friction engagement element 4, and is a hydraulic pressure higher than the release hydraulic pressure or 0 but lower than the engagement hydraulic pressure when the friction engagement element 4 is released. Such shift preparation control will be described in detail below, showing an example of the control.

[0037] The detection unit 5 is a device or apparatus for acquiring various data and information required to control the vehicle Ve, and includes, for example, a power supply unit, a microcomputer, a sensor, an input / output interface, etc. In particular, the detection unit 5 in this embodiment of the present invention detects various data and information for controlling the driving force source 1 (engine 7) and the automatic transmission 3, respectively. Specifically, the detection unit 5 has various sensors such as a vehicle speed sensor 5a that detects the vehicle speed from the rotation speed of the wheels, etc., an engine rotation speed sensor 5b that detects the rotation speed of the output shaft of the engine 7, a throttle opening sensor 5c that detects the opening of a throttle valve (not shown) of the engine 7, an accelerator opening sensor 5d that detects the amount of operation (opening) of the accelerator pedal (not shown), a master cylinder pressure sensor 5e that detects the oil pressure acting on a master cylinder (not shown) of the braking device, a brake sensor 5f that detects the amount of operation (stroke) of the brake pedal (not shown) of the braking device, an input shaft rotation speed sensor 5g that detects the rotation speed of the input shaft (not shown) of the automatic transmission 3, an output shaft rotation speed sensor 5h that detects the rotation speed of the output shaft 3a of the automatic transmission 3, an engagement pressure sensor 5i that detects the oil pressure (engagement oil pressure) acting on the friction engagement element 4 of the automatic transmission 3, and a timer 5j that measures the duration of control, waiting time, etc. The detection unit 5 is electrically connected to a controller 6, which will be described later, and outputs an electrical signal corresponding to the detected or calculated values ​​of the above-mentioned various sensors, devices, and apparatuses to the controller 6 as detection data.

[0038] The controller 6 is an electronic control device mainly composed of a microcomputer or the like, and in particular, the controller 6 in the embodiment of the present invention mainly controls the operation of the driving force source 1 (engine 7) and the operation of the automatic transmission 3. Various data detected or calculated by the detection unit 5 is input to the controller 6. The controller 6 performs calculations using the input various data as well as pre-stored data, calculation formulas, etc. The controller 6 then outputs control command signals based on the calculation results, and is configured to control the operation of the engine 7 and the gear shifting operation of the automatic transmission 3, etc. Note that while FIG. 1 shows an example in which one controller 6 is provided, multiple controllers 6 may be provided for each device or equipment to be controlled or for each control content.

[0039] As described above, when an automatic transmission 3 that hydraulically controls gear shifting is used, a response delay in the gear shift control inevitably occurs due to the responsiveness of the hydraulic control. Therefore, with conventional gear shift control, if the driver's accelerator pedal operation is inconsistent, a gear shift may occur unintentionally. For example, as shown in the time chart of FIG. 3, conventional gear shift control takes into account the response delay (hydraulic response delay) of the control and sets a gear shift threshold (shift line) so that the gear shift is initiated earlier than the timing or accelerator pedal position (point A) at which the gear shift is actually desired, i.e., at a low accelerator pedal position (point B). If gear shift control is performed based on such a gear shift threshold, for example, if the driver's accelerator operation fluctuates, repeatedly increasing and decreasing, as shown in the time chart of FIG. 4, a gear shift command may be output and a gear shift may be initiated before the desired accelerator pedal position (point C) is reached. This could result in a gear shift being performed against the driver's intention. Such an event occurs more frequently when the vehicle Ve has little margin of driving force, such as when the vehicle is traveling at high speed with a high-speed gear set in the automatic transmission 3. Therefore, the vehicle control device according to an embodiment of the present invention is configured to execute the control shown in the flowchart of Fig. 5 below, for example, in order to reduce the response delay of the gear shift control and to execute the gear shift as precisely as possible.

[0040] The control shown in the flowchart of Figure 5 is gear change control that is executed when the vehicle Ve is traveling at or above a predetermined vehicle speed, and typically shows an example of a downshift that shifts gears toward a gear with a larger gear ratio than the currently set gear. First, in step S1, it is determined whether the gear currently set in the automatic transmission 3 is the (x+1)th gear or higher. That is, it is determined whether the current gear is the (x+1)th gear, or a higher gear with a smaller gear ratio than the (x+1)th gear (for example, the (x+2)th gear or the (x+3)th gear).

[0041] If the current gear is lower than the (x+1)th gear, that is, a lower gear with a larger gear ratio than the (x+1)th gear (for example, the xth gear or the (x-1)th gear), and therefore the result of the negative determination in step S1 is false, the routine shown in the flowchart of FIG. 5 is temporarily terminated without executing any further control.

[0042] On the other hand, if the current gear is equal to or higher than the (x+1)th gear, that is, if the current gear is the (x+1)th gear or a higher gear with a smaller gear ratio than the (x+1)th gear and the answer is affirmative in step S1, the process proceeds to step S2.

[0043] In step S2, a determination is made as to whether or not shift preparation control is necessary. That is, a determination is made as to whether or not the operating condition of the vehicle Ve, based on the required driving force and vehicle speed, has exceeded a shift preparation threshold. Specifically, a determination is made as to whether or not the operating condition of the vehicle Ve has changed across the downshift preparation threshold in such a manner that the required driving force increases and the vehicle speed decreases. For example, on the shift map as shown in FIG. 2, a determination is made as to whether or not the output shaft rotation speed re of the automatic transmission 3, which corresponds to the vehicle speed, has become lower than the downshift preparation threshold (Down preparation line) from the (x+1)th gear to the xth gear, and the accelerator opening ta, which corresponds to the required driving force, has become higher than the downshift preparation threshold (Down preparation line) from the (x+1)th gear to the xth gear. That is, on the shift map of Figure 2, it is determined whether the operating condition of the vehicle Ve has changed across the downshift preparation threshold (Down preparation line) from the (x+1)th gear to the xth gear in the direction of increasing the accelerator opening ta and decreasing the output shaft rotation speed re.

[0044] If the answer to step S2 is affirmative because the operating condition of the vehicle Ve has changed in the direction of increasing the required driving force (accelerator opening ta) and decreasing the vehicle speed (output shaft rotation speed re), crossing the downshift preparation threshold (Down preparation line) from the (x+1)th gear to the xth gear, the process proceeds to step S3.

[0045] In step S3, gear shift preparation control is executed. That is, hydraulic pressure control is performed on the friction engagement elements 4 (clutches and brakes) that will be activated during a downshift scheduled thereafter, and the engaged and disengaged states are set to a gear shift preparation state for downshifting or a gear shift standby state (preparation phase). Specifically, in this gear shift preparation control, engagement preparation hydraulic pressure is supplied to the friction engagement elements 4 that are in the released state. Also, the engagement hydraulic pressure acting on the friction engagement elements 4 that are in the engaged state is reduced to release preparation hydraulic pressure. The engagement preparation hydraulic pressure is a target value of hydraulic pressure to be supplied to the friction engagement elements 4 that are in the released state, and is lower than the engagement hydraulic pressure supplied when engaging the friction engagement elements 4. By supplying this engagement preparation hydraulic pressure to the friction engagement elements 4 that are in the released state, the friction engagement elements 4 that are in the released state move slightly toward the engagement side while maintaining their released state, i.e., without entering an engaged state, and enter the gear shift preparation state (preparation phase). The release preparation hydraulic pressure is a target value for hydraulic pressure to be reduced from the friction engagement element 4 in an engaged state, and is a hydraulic pressure that is higher than the release hydraulic pressure or 0 and lower than the engagement hydraulic pressure when the friction engagement element 4 is released. By reducing the engagement hydraulic pressure acting on the friction engagement element 4 in an engaged state to this release preparation hydraulic pressure, the friction engagement element 4 in an engaged state moves slightly toward the release side while maintaining its engaged state, i.e., without entering a released state, and enters a gear shift preparation state (preparation phase).

[0046] Next, in step S4, it is determined whether or not shift control needs to be performed. That is, it is determined whether or not the operating condition of the vehicle Ve, based on the required driving force and vehicle speed, has exceeded a shift threshold. Specifically, it is determined whether or not the operating condition of the vehicle Ve has changed across the downshift threshold in such a way that the required driving force increases and the vehicle speed decreases. For example, on the shift map such as that shown in FIG. 2, it is determined whether or not the output shaft rotation speed re of the automatic transmission 3, which corresponds to the vehicle speed, has become lower than the downshift threshold (downshift line) from the (x+1)th gear to the xth gear, and the accelerator opening ta, which corresponds to the required driving force, has become higher than the downshift threshold (downshift line) from the (x+1)th gear to the xth gear. That is, on the shift map of Figure 2, it is determined whether the operating condition of the vehicle Ve has changed across the down shift threshold (Down shift line) from the (x+1)th gear to the xth gear in the direction of increasing the accelerator opening ta and decreasing the output shaft rotation speed re.

[0047] If the operating state of the vehicle Ve has not yet exceeded (crossed) the downshift threshold (downshift line) from the (x+1)th gear to the xth gear and therefore the determination in step S4 is negative, the process returns to step S2, and the same control as before is executed. Therefore, the shift preparation control continues until the determination in step S2 is negative. Alternatively, the shift preparation control continues until it is determined in step S4 that the operating state of the vehicle Ve has exceeded (crossed) the downshift threshold (downshift line) from the (x+1)th gear to the xth gear.

[0048] On the other hand, if the operating condition of the vehicle Ve has exceeded (crossed over) the downshift threshold (downshift line) from the (x+1)th gear to the xth gear and the result of the determination in step S4 is affirmative, the process proceeds to step S5.

[0049] In step S5, gear shift control is executed. That is, a downshift from the (x+1)th gear to the xth gear is performed. Once the gear shift control is executed in step S5, the routine shown in the flowchart of FIG. 5 is temporarily ended.

[0050] On the other hand, in the first routine of the flowchart of FIG. 5, if the operating state of the vehicle Ve has not yet changed across the downshift preparation threshold (Down preparation line) from the (x+1)th gear to the xth gear in the direction of increasing the required driving force (accelerator opening ta) and decreasing the vehicle speed (output shaft rotation speed re), and therefore the result of the negative determination in step S2 is that the process proceeds to step S6.

[0051] In this case, the shift preparation control has not yet been executed, and the friction engagement element 4 of the automatic transmission 3 has not yet entered the shift preparation state (preparation phase), i.e., the state is the same as when the shift preparation control and the preparation phase have ended. Therefore, in this case (first routine), no particular control is performed in step S6, and thereafter, the routine shown in the flowchart of FIG. 5 is temporarily ended.

[0052] Alternatively, if the operating state of the vehicle Ve crosses the downshift preparation threshold (Down preparation line) from the (x+1)th gear to the xth gear, and then does not cross the downshift threshold (Down preparation line), the output shaft rotation speed re again becomes higher than the downshift preparation threshold (Down preparation line) from the (x+1)th gear to the xth gear, or the accelerator opening ta becomes lower than the downshift preparation threshold (Down preparation line) from the (x+1)th gear to the xth gear, then the process proceeds to step S6.

[0053] In this case, the shift preparation control and the preparation phase are started once, but then the state returns to the state before the downshift preparation threshold (Down preparation line) from the (x+1)th gear to the xth gear is crossed without an actual shift (downshift). Therefore, in this case (a state in which the execution condition for the shift preparation control is not met), the shift preparation control and the preparation phase are ended in step S6.

[0054] Then, in step S6, when the shift preparation control and the preparation phase are completed, the routine shown in the flowchart of FIG. 5 is temporarily terminated.

[0055] As described above, in the vehicle control device according to the embodiment of the present invention, in addition to the shift threshold for executing an actual shift, a shift preparation threshold different from the shift threshold is set for the shift control of the automatic transmission 3. The shift preparation threshold is set, for example, on a shift map or shift line diagram, at a value that is parallel to the shift threshold (shift line) and near the shift threshold. The shift preparation control is executed when the operating state of the vehicle Ve based on the required driving force (accelerator opening) and the vehicle speed (output shaft rotation speed of the automatic transmission 3) exceeds (crosses) the shift preparation threshold before the shift threshold. In other words, the shift preparation control is executed before the automatic transmission 3 executes a shift. Execution of the shift preparation control supplies engagement preparation hydraulic pressure to the friction engagement element 4 in the disengaged state. Furthermore, engagement hydraulic pressure is discharged from the friction engagement element 4 in the engaged state. Therefore, the friction engagement element 4 in the disengaged state maintains its disengaged state, i.e., moves slightly toward the engagement side without entering an engaged state, thereby entering the shift preparation state. Furthermore, the friction engagement element 4 in the engaged state moves slightly toward the disengagement side while maintaining the engaged state, that is, without going into the disengaged state, and goes into the gear shift preparation state.

[0056] In conventional gear shift control that does not execute the gear shift preparation control according to the embodiment of the present invention, as shown in the time chart of FIG. 6, it takes a relatively long time for the frictional engagement element 4 in the disengaged state to actually rise in engagement oil pressure and enter the engaged state at time t3 after a gear shift command value is output at time t1. In other words, the response delay of the gear shift control (hydraulic control) is large. In contrast, by executing the gear shift preparation control according to the embodiment of the present invention, engagement preparation oil pressure is supplied to the frictional engagement element 4 in the disengaged state, and the frictional engagement element 4 in the disengaged state maintains its disengaged state, i.e., does not enter an engaged state, but slightly moves toward the engaging side, entering a gear shift preparation state (gear shift standby state). Then, when a gear shift command value is output to the frictional engagement element 4 in the gear shift preparation state at time t2, for example, the engagement oil pressure rises between time t2 and time t3, and the frictional engagement element 4 in the gear shift preparation state enters an engaged state. Therefore, the response delay of the gear shift control (hydraulic control) is significantly reduced compared to conventional gear shift control.

[0057] Similarly, in conventional gear shift control without executing the gear shift preparation control according to the embodiment of the present invention, as shown in the time chart of FIG. 7, it takes a relatively long time for the engaged frictional engagement element 4 to actually drop to the release hydraulic pressure and enter the released state at time t13 after the gear shift command value is output at time t11. In other words, there is a large response delay in gear shift control (hydraulic control). In contrast, by executing the gear shift preparation control according to the embodiment of the present invention, the engagement hydraulic pressure is discharged from the engaged frictional engagement element 4, and the hydraulic pressure acting on the engaged frictional engagement element 4 is lowered to the release hydraulic pressure, which is lower than the engagement hydraulic pressure. Therefore, the engaged frictional engagement element 4 maintains its engaged state, i.e., does not enter the released state, but moves slightly toward the release side, entering the gear shift preparation state (gear shift standby state). Then, for example, when a gear shift command value is output to the frictional engagement element 4 in the gear shift preparation state at time t12, the hydraulic pressure is lowered to the release hydraulic pressure from time t12 to time t13, and the frictional engagement element 4 in the gear shift preparation state enters the released state. Therefore, compared to conventional gear shift control, the response delay of gear shift control (hydraulic control) is significantly reduced.

[0058] 5 shows an example in which a downshift is performed in the automatic transmission 3. However, the vehicle control device according to the embodiment of the present invention can also perform the same shift preparation control and achieve the same effects when an upshift is performed in the automatic transmission 3. That is, the shift preparation thresholds according to the embodiment of the present invention are configured with an upshift preparation threshold (Up preparation line in FIG. 2 ) that is set near the upshift threshold (Up shift line in FIG. 2 ) at a higher required driving force (accelerator opening degree ta) and at a lower vehicle speed (output shaft rotation speed re) than the upshift threshold, and a downshift preparation threshold (Down preparation line in FIG. 2 ) that is set near the downshift threshold (Down shift line in FIG. 2 ) at a lower required driving force and at a higher vehicle speed than the downshift threshold. Therefore, in the vehicle control device according to the embodiment of the present invention, the operating state of the vehicle Ve crosses the upshift preparation threshold before crossing the upshift threshold, and the shift preparation control is thereby executed. In other words, prior to the execution of an upshift, the gear shift preparation control for the upshift is executed. Similarly, in the vehicle control device of the present invention, the operating state of the vehicle Ve crosses the downshift preparation threshold before crossing the downshift threshold, which causes the gear shift preparation control to be executed. In other words, prior to the execution of a downshift, the gear shift preparation control for the downshift is executed.

[0059] The vehicle control device in this embodiment of the present invention can also execute the control shown in the flowchart of Figure 8 by selecting the manual shifting mode and controlling a vehicle Ve equipped with an automatic transmission 3 that is capable of manual shifting and changes gears in response to the driver's shifting operation.

[0060] The control shown in the flowchart of Figure 8 is a shift control that is executed when the vehicle Ve is traveling at a predetermined vehicle speed or higher, and in this case, too, a representative example is shown of downshifting of the automatic transmission 3. First, in step S11, it is determined whether or not a manual shift mode has been selected.

[0061] If the manual shift mode (manual shift mode) has not been selected and therefore a negative determination is made in step S11, the routine shown in the flowchart of FIG. 5 is temporarily ended without executing the subsequent control.

[0062] On the other hand, if the manual shift mode is selected and the answer to step S11 is affirmative, the process proceeds to step S12.

[0063] In step S12, it is determined whether the gear currently set in the automatic transmission 3 is equal to or higher than the (x+1)th gear. That is, it is determined whether the current gear is the (x+1)th gear, or a higher-speed gear with a smaller gear ratio than the (x+1)th gear (for example, the (x+2)th gear or the (x+3)th gear).

[0064] If the current gear is lower than the (x+1)th gear, i.e., a lower gear with a larger gear ratio than the (x+1)th gear (e.g., xth gear, (x-1)th gear), and the result of this step S11 is negative, the process proceeds to step S13.

[0065] This step S13 is a control step that ends the shift preparation control and the preparation phase, but in the first routine of the flowchart in Fig. 8, the shift preparation control has not yet been executed, and the friction engagement element 4 of the automatic transmission 3 is not yet in a shift preparation state (preparation phase), that is, it is in a state similar to when the shift preparation control and the preparation phase have ended. Therefore, in this case (first routine), no particular control is performed in step S13, and thereafter the routine shown in the flowchart in Fig. 8 is temporarily ended.

[0066] On the other hand, if the current gear is equal to or higher than the (x+1)th gear, that is, if the current gear is the (x+1)th gear or a higher gear with a smaller gear ratio than the (x+1)th gear and the answer is affirmative in step S12, the process proceeds to step S14.

[0067] In step S14, it is determined whether the amount of brake pedal operation (brake operation amount) ba by the driver is greater than a manual shift preparation threshold. The manual shift preparation threshold is a shift preparation threshold used to determine whether shift preparation control should be performed in manual shift mode, and is a threshold that defines at least one reference value of an acceleration request amount (e.g., accelerator opening, throttle valve opening, fuel injection amount, etc.) based on the driver's driving operation (accelerator operation and brake operation) or a deceleration request amount (e.g., brake operation amount, brake stroke, pedal force, master cylinder pressure, etc.) based on the driver's driving operation. Prior to the execution of a shift in automatic transmission 3, the shift preparation control is executed when the actual acceleration request amount or the actual deceleration request amount exceeds (exceeds) this manual shift preparation threshold. In the example shown in the flowchart of FIG. 8, the manual shift preparation threshold is a manual downshift preparation threshold for the brake operation amount ba, and when the brake operation amount ba exceeds the manual downshift preparation threshold, it is predicted that the driver will immediately perform a downshift in manual shift mode. Alternatively, it is determined that there is a high possibility that the driver will perform a downshift in the manual shift mode, and shift preparation control is initiated prior to the execution of the downshift in the manual shift mode.

[0068] Note that, instead of the control of comparing the brake operation amount ba with the manual downshift preparation threshold for that brake operation amount ba as described above, the control of step S14 may be control of comparing the accelerator operation amount (or accelerator opening) with the manual downshift preparation threshold for that accelerator operation amount. Alternatively, the control may be control of comparing the brake operation amount ba with the manual upshift preparation threshold for that brake operation amount ba. Alternatively, the control may be control of comparing the accelerator operation amount (or accelerator opening) with the manual upshift preparation threshold for that accelerator operation amount. The manual upshift preparation threshold predicts that an upshift in the manual shift mode will be performed by the driver immediately after the brake operation amount ba or the accelerator operation amount exceeds the manual upshift preparation threshold. Alternatively, it determines that there is a high possibility that an upshift in the manual shift mode will be performed by the driver. Then, the shift preparation control is started prior to the upshift in the manual shift mode.

[0069] The manual downshift preparation threshold is set to a value lower than the value of the brake operation amount corresponding to the shift threshold (shift line), for example, as shown in Fig. 9. Alternatively, it is set to a value lower than the value of the accelerator operation amount corresponding to the shift threshold (shift line). Similarly, the manual upshift preparation threshold is set to a value lower than the value of the brake operation amount corresponding to the shift threshold (shift line), for example, as shown in Fig. 9. Alternatively, it is set to a value lower than the value of the accelerator operation amount corresponding to the shift threshold (shift line).

[0070] In step S14, the manual shift preparation threshold is used to predict the driver's intention to accelerate or decelerate from the amount of acceleration or deceleration required based on the driver's driving operation, and the driver's manual shift operation is predicted based on the intention to accelerate or decelerate, so that the shift preparation control can be started prior to the driver's manual shift operation.As a result, the shift preparation control in this embodiment of the present invention can be executed effectively.

[0071] Note that the control of determining whether to execute the shift preparation control using the manual shift preparation threshold as shown in step S14 can also be applied, for example, to a normal state (automatic shift mode n) that is not the manual shift mode of the automatic transmission 3 as described above. That is, instead of the manual shift preparation threshold, predicted shift preparation thresholds (predicted downshift preparation threshold, predicted upshift preparation threshold) may be set, and instead of the manual shift operation by the driver, the possibility of shifting in the automatic transmission 3 may be predicted, and the shift preparation control may be executed based on the prediction result.

[0072] Therefore, if the brake operation amount ba is greater than the manual shift preparation threshold (manual downshift preparation threshold) and therefore the answer to step S14 is affirmative, the process proceeds to step S15.

[0073] In step S15, gear shift preparation control is executed. That is, hydraulic pressure control is performed on the friction engagement elements 4 (clutches and brakes) that will be activated during a downshift that is predicted to be performed later by manual operation by the driver, and their engaged and released states are set to a gear shift preparation state for downshifting or a gear shift standby state (preparation phase). Specifically, engagement preparation hydraulic pressure is supplied to the friction engagement element 4 in the released state. Furthermore, the engagement hydraulic pressure acting on the friction engagement element 4 in the engaged state is reduced to release preparation hydraulic pressure. The engagement preparation hydraulic pressure is a target value of hydraulic pressure to be supplied to the friction engagement element 4 in the released state, and is lower than the engagement hydraulic pressure supplied when engaging the friction engagement element 4. By supplying this engagement preparation hydraulic pressure to the friction engagement element 4 in the released state, the friction engagement element 4 in the released state moves slightly toward the engagement side while maintaining its released state, i.e., without entering an engaged state, and enters the gear shift preparation state (preparation phase). The release preparation hydraulic pressure is a target value for hydraulic pressure to be reduced from the friction engagement element 4 in an engaged state, and is a hydraulic pressure that is higher than the release hydraulic pressure or 0 and lower than the engagement hydraulic pressure when the friction engagement element 4 is released. By reducing the engagement hydraulic pressure acting on the friction engagement element 4 in an engaged state to this release preparation hydraulic pressure, the friction engagement element 4 in an engaged state moves slightly toward the release side while maintaining its engaged state, i.e., without entering a released state, and enters a gear shift preparation state (preparation phase).

[0074] Next, in step S16, it is determined whether a manual downshift operation has been performed by the driver. For example, it is determined whether a shift device (not shown) of the automatic transmission 3 has been operated by the driver. If a negative determination is made in step S16 because the driver has not yet performed a manual downshift operation, the process returns to step S14, and the same control as before is executed. Therefore, the shift preparation control continues until a negative determination is made in step S14 because the brake operation amount ba has decreased to or below the predicted shift preparation threshold. Alternatively, the shift preparation control continues until a manual downshift operation has been performed by the driver is determined in step S16.

[0075] If the answer to step S16 is YES because the driver has manually downshifted the transmission, the process proceeds to step S17.

[0076] In step S17, gear shift control is executed. That is, a downshift from the (x+1)th gear to the xth gear is performed. Once the gear shift control is executed in step S17, the routine shown in the flowchart of FIG. 8 is temporarily ended.

[0077] On the other hand, if the brake operation amount ba is equal to or less than the predicted shift preparation threshold value and therefore the answer to the question in step S14 is NO, the process proceeds to step S18.

[0078] In step S18, it is determined whether the duration ti of the gear shift preparation control is longer than 0 and shorter than an upper limit. The duration ti is the time from the start of execution of the gear shift preparation control to the present, and the upper limit in this case is a predetermined reference value for the duration ti. If the duration ti exceeds the upper limit, the gear shift preparation control is terminated.

[0079] If the duration ti of the shift preparation control is longer than 0 and shorter than the upper limit value, and therefore the answer to step S18 is affirmative, the process proceeds to step S16, where the same control as before is executed.

[0080] On the other hand, if the determination in step S18 is negative because the duration ti of the gear shift preparation control is 0 or the duration ti of the gear shift preparation control has exceeded the upper limit, the process proceeds to step S13. Note that in the first routine of the flowchart in Fig. 8, the gear shift preparation control has not yet been executed, so the duration ti of the gear shift preparation control is 0.

[0081] If the duration ti of the shift preparation control is 0, the shift preparation control has not yet been executed, and the friction engagement element 4 of the automatic transmission 3 is not yet in a shift preparation state (preparation phase), that is, the state is the same as when the shift preparation control and the preparation phase have ended. Therefore, in this case (first routine), no particular control is performed in step S13, and thereafter, the routine shown in the flowchart of FIG. 5 is temporarily ended.

[0082] In addition, if the duration ti of the shift preparation control exceeds the upper limit value, the shift preparation control and the preparation phase are terminated in order to suppress an increase in loss due to the continuation of the shift preparation control and to protect the friction engagement element 4 of the automatic transmission 3.

[0083] In the above-described gear shift preparation control, for example, if the duration ti of the gear shift preparation control becomes excessively long, losses increase and the energy efficiency of the vehicle Ve may decrease. Furthermore, if the slip state of the frictional engagement element 4 is permitted and the slip state continues for an excessively long time, wear and deterioration of the frictional engagement element 4 may progress. For this reason, in the control of step S18, an upper limit is set for the duration ti of the gear shift preparation control.

[0084] Note that, in the control of step S18, instead of setting an upper limit on the duration ti as described above, an upper limit (reference heat amount) may be set on the amount of heat absorption (or heat generation amount) of the frictional engagement element 4 during the duration ti, and the shift preparation control may be terminated when the amount of heat absorption by the frictional engagement element 4 exceeds the upper limit. Alternatively, the shift preparation control may be terminated when both the duration ti and the amount of heat absorption by the frictional engagement element 4 exceed their respective upper limits. The amount of heat absorption by the frictional engagement element 4 can be estimated and calculated from, for example, the duration ti, the amount of slippage (differential rotation) of the frictional engagement element 4, and the pressing force (engagement pressure) of the frictional engagement element 4.

[0085] Therefore, by the control of step S18, if the duration ti of the gear shift preparation control is extended due to the driving state of the vehicle Ve while the slip state of the frictional engagement element 4 is permitted during the gear shift preparation control, the execution of the gear shift preparation control can be canceled. This makes it possible to prevent an increase in loss and a decrease in the energy efficiency of the vehicle Ve due to the frictional engagement element 4 continuing in a slip state for a long period of time during the gear shift preparation control. It is also possible to prevent a decrease in the durability of the frictional engagement element 4.

[0086] Furthermore, the control of step S18 and the control of setting an upper limit (reference heat amount) on the amount of heat absorption by the frictional engagement element 4 as described above, i.e., the control of setting an upper limit on the shift preparation control, may be applied to, for example, the control shown in the flowchart of Fig. 5 described above. In the control shown in the flowchart of Fig. 5, by setting an upper limit on the shift preparation control, it is possible to prevent a decrease in the energy efficiency of the vehicle Ve, as described above. It is also possible to prevent a decrease in the durability of the frictional engagement element 4.

[0087] Then, in step S6, when the shift preparation control and the preparation phase are completed, the routine shown in the flowchart of FIG. 5 is temporarily terminated.

[0088] As described above, according to the vehicle control device of the embodiment of the present invention, a shift preparation threshold as described above is set in addition to the normal shift threshold (shift line), and shift preparation control is executed based on the shift preparation threshold. By executing the shift preparation control of the embodiment of the present invention, the engagement hydraulic pressure of the frictional engagement element 4, which is engaged or disengaged to achieve an upshift or downshift, is preliminarily controlled prior to the actual execution of the upshift or downshift. That is, the engagement hydraulic pressure is increased or decreased within a range in which the frictional engagement element 4 does not switch between engaged and disengaged states, or within a range in which an actual shift does not occur, to bring the frictional engagement element 4 into a shift preparation state. By bringing the frictional engagement element 4 into a shift preparation state in advance of the actual shift, it is possible to reduce the hydraulic response delay, which is a major factor in the response delay of shift control. Therefore, the shift threshold, which was previously set to anticipate a relatively large response delay, can be set to anticipate only the minimum response delay reduced by the shift preparation control. Therefore, the automatic transmission can be shifted at the appropriate timing as originally intended or close to the original target. [Explanation of symbols]

[0089] 1. Driving force source 2 drive wheels 3 Automatic transmission (AT) 3a (automatic transmission) output shaft 4 Friction engagement element 5. Detection unit 5a (detection section) vehicle speed sensor 5b (detection part) engine speed sensor 5c (detection part) throttle opening sensor 5d (Detection section) Accelerator opening sensor 5e Master cylinder pressure sensor (detection section) 5f Brake sensor (detection section) 5g (Detection section) Input shaft rotation speed sensor 5h (Detection section) Output shaft rotation speed sensor 5i (Detection section) Engagement pressure sensor 5j (Detector) Timer 6 Controller (ECU) 7 Engine (ENG; driving force source) 8 propeller shaft 9 Differential gear 10 Drive shaft 11 Power transmission path Vehicle

Claims

1. A control device for a vehicle that is equipped with an automatic transmission that is capable of shifting by switching between a plurality of gear stages each having a different gear ratio by hydraulically controlling the engaged and disengaged states of friction engagement elements, and that determines whether to execute the shift using a shift threshold that defines the relationship between a required driving force and a vehicle speed as a determination criterion, a controller that executes hydraulic control to supply, to the friction engagement element in a released state, an engagement hydraulic pressure that causes the friction engagement element in the released state to be in an engaged state, or to reduce, to the friction engagement element in an engaged state, the engagement hydraulic pressure to a release hydraulic pressure that causes the friction engagement element in the engaged state to be in a released state, and selectively sets one of the gear stages; The controller When the driving state based on the required driving force and the vehicle speed exceeds the shift threshold, the shift is performed to switch the gear position, and a shift preparation threshold different from the shift threshold, Prior to the execution of the shift, when the operating state exceeds the shift preparation threshold, a shift preparation control is executed in which an engagement preparation oil pressure lower than the engagement oil pressure is supplied to the friction engagement element in the released state while maintaining the released state, or the engagement oil pressure is reduced to a release preparation oil pressure lower than the engagement oil pressure and higher than the release oil pressure while maintaining the engaged state of the friction engagement element. A vehicle control device comprising:

2. The vehicle control device according to claim 1, The controller The shift thresholds include an upshift threshold for determining execution of an upshift to perform the shift to a gear stage having a smaller gear ratio than the currently set gear stage, and a downshift threshold for determining execution of a downshift to perform the shift to a gear stage having a larger gear ratio than the currently set gear stage, When the driving state changes across the upshift threshold in a direction in which the required driving force becomes lower and the vehicle speed becomes higher, the upshift is performed; when the driving state changes across the downshift threshold in a direction in which the required driving force becomes higher and the vehicle speed becomes lower, the downshift is performed; and The gear shift preparation thresholds include an upshift preparation threshold that is set near the upshift threshold, where the required driving force is higher than the upshift threshold and the vehicle speed is lower, and defines a relationship between the required driving force and the vehicle speed in parallel with the upshift threshold, and a downshift preparation threshold that is set near the downshift threshold, where the required driving force is lower than the downshift threshold and the vehicle speed is higher, and defines a relationship between the required driving force and the vehicle speed in parallel with the downshift threshold, When the driving state changes across the upshift preparation threshold in a direction in which the required driving force becomes lower and the vehicle speed becomes higher, the gear shift preparation control is executed prior to the execution of the upshift, and when the driving state changes across the downshift preparation threshold in a direction in which the required driving force becomes higher and the vehicle speed becomes lower, the gear shift preparation control is executed prior to the execution of the downshift. A vehicle control device comprising:

3. The vehicle control device according to claim 1, The controller the shift preparation threshold for determining whether the shift preparation control is to be executed includes a predicted shift preparation threshold that defines a reference value of at least one of an acceleration request amount based on a driving operation of a driver and an deceleration request amount based on the driving operation, acquiring at least one of the actual acceleration request amount and the actual deceleration request amount; The shift preparation control is executed when the acquired acceleration request amount or deceleration request amount exceeds the predicted shift preparation threshold value prior to the execution of the shift. A vehicle control device comprising:

4. The vehicle control device according to claim 3, The controller The shift thresholds include an upshift threshold for determining execution of an upshift to perform the shift to a gear stage having a smaller gear ratio than the currently set gear stage, and a downshift threshold for determining execution of a downshift to perform the shift to a gear stage having a larger gear ratio than the currently set gear stage, When the driving state changes across the upshift threshold in a direction in which the required driving force becomes lower and the vehicle speed becomes higher, the upshift is performed; when the driving state changes across the downshift threshold in a direction in which the required driving force becomes higher and the vehicle speed becomes lower, the downshift is performed; and The predicted shift preparation thresholds include a predicted upshift preparation threshold for predicting the execution of the upshift and determining whether to execute the shift preparation control, and a predicted downshift preparation threshold for predicting the execution of the downshift and determining whether to execute the shift preparation control, When the actual acceleration request amount becomes larger than the predicted upshift preparation threshold, the shift preparation control is executed prior to the execution of the upshift, and when the actual deceleration request amount becomes larger than the predicted downshift preparation threshold, the shift preparation control is executed prior to the execution of the downshift. A vehicle control device comprising:

5. The vehicle control device according to claim 1, The automatic transmission is capable of manual shifting in which the gear shift is performed in response to a driver's shifting operation by selecting a manual shifting mode, The controller the shift preparation threshold is for determining whether the shift preparation control is to be executed in the manual shift mode, and the manual shift preparation threshold defines at least one of a reference value of an acceleration request amount based on a driving operation of the driver and a reference value of a deceleration request amount based on the driving operation, acquiring at least one of the actual acceleration request amount and the actual deceleration request amount; In the manual shift mode, the shift preparation control is executed when the acquired acceleration request amount or deceleration request amount exceeds the manual shift preparation threshold value prior to the execution of the manual shift. A vehicle control device comprising:

6. The vehicle control device according to claim 5, The controller The manual shift preparation thresholds include a manual upshift preparation threshold for determining whether to execute the shift preparation control by predicting that the driver will perform an upshift operation to change the gear to a gear having a smaller gear ratio than the currently set gear, and a manual downshift preparation threshold for determining whether to execute the shift preparation control by predicting that the driver will perform a downshift operation to change the gear to a gear having a larger gear ratio than the currently set gear, In the manual shift mode, The upshift or the downshift is performed in response to the gear shift operation, When the actual acceleration request amount becomes larger than the manual upshift preparation threshold, the shift preparation control is executed prior to the execution of the upshift, and when the actual deceleration request amount becomes larger than the manual downshift preparation threshold, the shift preparation control is executed prior to the execution of the downshift. A vehicle control device comprising:

7. The vehicle control device according to any one of claims 1 to 6, The controller When the shift preparation control is executed, At least one of the duration from the point in time when the execution of the shift preparation control is started and the heat absorption amount of the friction engagement element during the duration is acquired, The shift preparation control is terminated at least when the duration exceeds a predetermined reference time or when the amount of absorbed heat exceeds a predetermined reference heat amount. A vehicle control device comprising:

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