JP2020083174A - Control device of vehicle - Google Patents

Abstract

To effectively achieve both protection of a friction fastening element for start and improvement of start responsiveness when starting a vehicle from an accelerator hill hold state in an uphill road.SOLUTION: A control device of a vehicle includes: fastening power control means for controlling fastening power of a friction fastening element for start for connecting and disconnecting an engine and a driving wheel; brake control means for actuating a brake device irrespective of a brake pedal operation; gradient load torque calculation means; required driving torque calculation means; and uphill road braking control means for maintaining a braking state of a vehicle while suppressing a thermal load of the friction fastening element for start when required driving torque T1 is larger than zero and is equal to or smaller than the gradient load torque T2 on an uphill road. The uphill road braking control means performs fastening power limiting control for limiting fastening power of the friction fastening element for start so that transmission torque TCL at a prescribed ratio R1 to the required driving torque T1 is generated while operating the brake device.SELECTED DRAWING: Figure 3

Description

The present invention relates to a vehicle control device that transmits a driving force of a driving source to driving wheels via a friction fastening element.

There is a case where a vehicle such as an automobile performs an accelerator hill hold in which a vehicle is stopped on an uphill road by using a required driving force by a driver depressing an accelerator pedal instead of operating a brake pedal. In the accelerator hill hold, the braking state is maintained by balancing the slip-down torque (hereinafter also referred to as “gradient load torque”) due to the vehicle weight on the uphill road and the required drive torque corresponding to the required drive force. A differential rotation occurs between the drive source and the drive wheels. In a vehicle equipped with an automatic transmission, due to this differential rotation, the starting frictional engagement element between the drive source and the drive wheels slides, and an excessive heat load is applied to the starting frictional engagement element. The durability of the starting frictional fastening element is likely to decrease.

On the other hand, a vehicle may be provided with a second brake device that performs braking independently of the foot brake device that performs braking in response to a normal operation of a brake pedal. In this type of vehicle, when accelerator hill hold is performed on an uphill road and the required drive torque is smaller than the gradient load torque, the starting friction coupling element is maintained while the braking state is maintained by the operation of the second brake device. Braking control for releasing (hereinafter, also referred to as "uphill braking control") may be performed. As a result, it is possible to prevent the vehicle from retreating and to suppress the deterioration of durability due to the slip of the starting frictional fastening element.

If the required drive torque becomes larger than the gradient load torque during the execution of the uphill braking control, the uphill braking control ends and the vehicle starts. At the time of starting the vehicle, it is necessary to engage the starting frictional engagement element and release the second brake device. Therefore, the start may be delayed by the time required for these operations.

On the other hand, in Patent Document 1, first, based on the differential rotation between the drive source and the drive wheels, it is determined whether or not slippage has occurred in the starting frictional fastening element, and when slippage has occurred, There is disclosed a vehicle control device that determines whether or not to perform uphill road braking control, depending on the heat load (for example, the degree of slippage or heat generation) of a start frictional engagement element.

Specifically, in the vehicle control device disclosed in Patent Document 1, the target drive torque is calculated based on the accelerator opening degree, and when the target drive torque is larger than 0 and the vehicle speed is almost 0, Based on the differential rotation between the drive source and the drive wheels, it is determined whether or not the vehicle is in a stalled state where slippage occurs in the starting friction element.

When the vehicle is in the stalled state, whether or not to perform the uphill braking control is determined according to the degree of heat load of the starting frictional engagement element. For example, if the heat load is less than a predetermined value on an uphill road with a gentle slope, the uphill road braking control is not executed, so that a good start response can be secured. On the contrary, if the load is equal to or higher than a predetermined heat load on a steep slope, the slope braking control is executed to suppress heat generation in the starting frictional engagement element. As described above, in the technique of Patent Document 1, whether or not the uphill road braking control is executed is determined according to the situation, so that the balance between the protection of the starting frictional engagement element and the securing of the starting response performance is achieved. There is.

JP, 2013-33903, A

By the way, the starting response performance of a vehicle on an uphill road tends to be more demanded on a steep uphill road than on a gentle uphill road. However, in the vehicle control device of Patent Document 1, since the uphill road braking control is performed on a steep uphill road where the slippage of the starting frictional engagement element during the execution of the accelerator hill hold becomes large, the required drive torque When the uphill road braking control ends due to the increase and the vehicle starts, as described above, it takes time to engage the starting frictional engagement element and release the second brake device. I can't improve. Therefore, there is room for improvement in improving the starting response from the accelerator hill hold.

Further, in the vehicle control device of Patent Document 1, in a stall state on a gentle uphill where the uphill braking control is not executed, the heat generation amount in the starting frictional engagement element in the slip state is larger than that in the completely released state. Prone. Therefore, there is room for improvement in always protecting the starting frictional engagement element during execution of the accelerator hill hold.

Therefore, the present invention provides a vehicle control device capable of effectively achieving both protection of a starting frictional engagement element and improvement of starting responsiveness when the vehicle starts from an accelerator hill hold state on an uphill road. The challenge is to provide.

First, the invention according to claim 1 of the present application is
A starting frictional engagement element that is interposed between a power source and a drive wheel to connect and disconnect the power source and the drive wheel,
Fastening force control means for controlling the fastening force of the starting frictional fastening element,
Brake control means for operating the brake device regardless of brake pedal operation,
A road surface slope detecting means for detecting a road surface slope,
Gradient load torque calculating means for calculating a gradient load torque acting on the wheels based on the road surface gradient,
Accelerator opening detection means for detecting the accelerator opening,
A required drive torque calculating means for calculating a required drive torque based on the accelerator opening,
When the road surface is an uphill slope and the required drive torque is larger than zero and is equal to or smaller than the slope load torque, a slope for maintaining the braking state of the vehicle while suppressing the thermal load of the starting frictional engagement element. An uphill road braking control means for executing road braking control, and a control device for a vehicle comprising:
In the uphill road braking control, the uphill road braking control means operates the brake device by the brake control means, while the fastening force control means causes the transfer torque of a predetermined ratio with respect to the required drive torque to be used for the start. It is characterized in that fastening force limiting control is performed to limit the fastening force of the starting friction fastening element so as to be generated by the friction fastening element.

The “predetermined ratio” here is a ratio that is larger than 0% and smaller than 100%.

Further, the invention described in claim 2 is the same as the invention described in claim 1,
The uphill road braking control means, when the required drive torque increases to a predetermined lower reference value smaller than the gradient load torque, ends the fastening force limiting control by the fastening force control means, and It is characterized in that a complete engagement control for completely engaging the start friction engagement element is started.

The "lower reference value" here is, for example, to the extent that it can be reasonably determined that it is certain that the vehicle will soon start or that the driver has increased the accelerator pedal with the intention of starting the vehicle. The magnitude of the required drive torque when the required drive torque is increased, that is, a value slightly smaller than the gradient load torque is set.

Further, the invention according to claim 3 is the same as the invention according to claim 1 or claim 2,
The uphill braking control means causes the brake control means to release the operation of the brake device when the transmission torque in the starting frictional engagement element increases to a predetermined upper reference value that is larger than the gradient load torque. Is characterized by.

The "upper reference value" here is, for example, the magnitude of the transmission torque at the timing immediately after the transmission torque in the starting frictional engagement element exceeds the gradient load torque, that is, a value slightly larger than the gradient load torque. Is set to.

The timing at which the transmission torque of the starting frictional engagement element reaches the "upper reference value" is the timing at which the starting frictional engagement element is completely engaged, that is, the transmission torque of the starting frictional engagement element is required to drive. It may coincide with the timing of rising until it coincides with the torque.

Further, the invention according to claim 4 is the invention according to any one of claims 1 to 3,
Temperature detecting means for detecting a temperature related to the temperature of the starting frictional fastening element,
Ratio setting means for setting the predetermined ratio to be lower as the temperature detected by the temperature detecting means is higher.

As used herein, the "temperature related to the temperature of the starting friction engaging element" includes, for example, the temperature of oil around the starting friction engaging element, the temperature of oil stored in the transmission case, and the starting friction. Examples include the temperature of the fastening element parts themselves.

The invention described in claim 5 is the same as the invention described in claim 4,
During the execution of the fastening force limit control, the time period during which the transmission torque of the starting frictional fastening element is maintained at the torque of the predetermined ratio is limited, and when the limited time period elapses, the fastening force control means controls the torque. Time limiting means for further reducing the fastening force of the starting friction fastening element,
And a time limit setting means for setting a shorter time limit by the time limit means as the temperature detected by the temperature detection means becomes higher.

Further, the invention according to claim 6 is the invention according to any one of claims 1 to 3,
Rotational speed difference detection means for detecting a difference between the input side rotational speed and the output side rotational speed of the starting frictional fastening element,
And a ratio setting unit that sets the predetermined ratio to a lower value as the value detected by the rotation speed difference detection unit increases.

The “ratio setting means” described in claim 6 may be different from or the same as the “ratio setting means” described in claim 4. In the former case, both “ratio setting means” are not provided in the vehicle control device according to the present invention, and only one of the “ratio setting means” may be selectively provided. In the latter case, the “ratio setting unit” sets a predetermined ratio based on one or both of the “temperature detected by the temperature detection unit” and the “value detected by the rotational speed difference detection unit”.

The invention described in claim 7 is the same as the invention described in claim 6,
During the execution of the fastening force limit control, the time period during which the transmission torque of the starting frictional fastening element is maintained at the torque of the predetermined ratio is limited, and when the limited time period elapses, the fastening force control means controls the torque. Time limiting means for further reducing the fastening force of the starting friction fastening element,
It is characterized by further comprising a time limit setting means for setting a shorter time limit by the time limit means as the value detected by the rotation speed difference detection means increases.

The "time limit setting means" described in claim 7 is different from the "time limit setting means" described in claim 5, and both "time limits" are set in the vehicle braking device according to the present invention. The "setting means" is not provided, and only one of the "time limit setting means" may be selectively provided.

According to the invention described in claim 1, during the execution of the uphill road braking control, the engagement force of the starting frictional engagement element is controlled so that the transmission torque of a predetermined ratio with respect to the required drive torque is generated. Therefore, during the execution of the uphill braking control, as compared with the case where the starting frictional engagement element is completely released, a good starting response is obtained at the end of the uphill braking control, and the driving torque is tentatively matched. As compared with the case where the transmission torque is generated in the starting frictional fastening element, heat generation in the starting frictional fastening element can be suppressed. Therefore, according to the present invention, the starting responsiveness is improved and the starting frictional fastening element is protected regardless of the gradient of the uphill road (a gentle uphill road to a steep uphill road) and the load of the starting frictional fastening element. It is always possible to effectively achieve both.

Further, according to the invention described in claim 2, before the required drive torque reaches the gradient load torque, that is, before the start of the vehicle is started, for example, at a proper timing immediately before the start, at a predetermined ratio. The complete engagement control of the engaged start friction engagement element is started. This complete engagement control is completed more quickly than if it was started in the complete disengaged state, so that the start response performance is prevented from being hindered by the uphill road braking control.

Further, according to the invention described in claim 3, the brake device is released, for example, at a timing when the vehicle starts to start after the transmission torque exceeds the gradient load torque, so that the accelerator hill hold on an uphill road is performed. During the execution of, the vehicle can be surely prevented from sliding down.

According to the fourth aspect of the present invention, the fastening force of the starting frictional fastening element is limited to a lower value as the temperature of the starting frictional fastening element increases during the execution of the fastening force limiting control in the uphill braking control. Specifically, in a situation where the temperature of the starting friction engaging element is high and deterioration due to heat generation is likely to occur, the engagement ratio of the starting friction engaging element is reduced (controlled to the disengagement side), so deterioration of the starting friction engaging element occurs. Suppression can be given priority. On the other hand, in a situation where the temperature of the starting friction element is relatively low and the deterioration is relatively difficult to proceed, the engagement ratio of the starting friction engaging element is increased, so that the starting responsiveness can be improved preferentially.

Therefore, since the engagement ratio is appropriately controlled according to the temperature of the starting frictional fastening element, the deterioration of the starting frictional fastening element is effectively suppressed while minimizing the sacrifice of the starting response performance. be able to.

Further, according to the invention described in claim 5, when the temperature of the starting frictional fastening element is high and deterioration due to heat generation is likely to proceed, the time limiting means has a relatively low temperature of the starting frictional fastening element. Compared with the case where the deterioration is relatively difficult to proceed, the time for maintaining the transmission torque of the starting frictional engagement element at the torque of a predetermined ratio with respect to the required drive torque is limited. Therefore, when the starting frictional fastening element is at a high temperature, the fastening force of the starting frictional fastening element is relatively quickly reduced, and further heat generation of the starting frictional element is suppressed. The deterioration can be effectively suppressed.

According to the invention described in claim 6, as the difference between the input speed and the output speed of the starting frictional engagement element increases during execution of the engaging force limiting control in the uphill road braking control, the starting effect is increased. The fastening force of the friction fastening element is limited to a low level. Specifically, due to the large difference between the input side rotation speed and the output side rotation speed of the start friction engagement element, the start friction engagement element is likely to be slipped and deteriorated easily by heat generation. Since the fastening element is controlled to the disengagement side, deterioration of the starting friction fastening element can be effectively suppressed. On the other hand, in a situation where the difference between the input side rotation speed and the output side rotation speed of the starting friction engagement element is relatively small and deterioration is relatively difficult to proceed, the engagement ratio of the starting friction engagement element is increased to improve the starting response. Can be achieved with priority.

Therefore, since the ratio of the fastening force is appropriately controlled according to the difference between the input and output rotational speeds of the starting frictional fastening element, deterioration of the starting frictional fastening element is suppressed while minimizing the sacrifice of the starting response performance. Can be effectively suppressed.

Further, according to the invention described in claim 7, when the difference between the input and output rotational speeds of the starting frictional fastening element is large and deterioration due to heat generation is likely to progress, the time limiting means inputs and outputs the starting frictional fastening element. Compared to the case where the difference in rotation speed is small and the deterioration due to heat generation is relatively difficult to progress, the time period for maintaining the transmission torque of the starting frictional fastening element at a predetermined ratio of torque to the required drive torque is limited. Therefore, when the difference between the input and output rotational speeds of the starting frictional fastening element is relatively large, the fastening force of the starting frictional fastening element is reduced relatively quickly, and further heat generation of the starting frictional fastening element is suppressed. Therefore, deterioration of the starting frictional fastening element can be effectively suppressed.

FIG. 1 is a schematic configuration diagram of a vehicle including a vehicle control device according to an embodiment of the present invention. 1 is a system diagram of a vehicle control device according to an embodiment of the present invention. It is a flowchart which shows an example of operation|movement of the control apparatus of the vehicle in an uphill road. It is a time chart which shows an example of a change over time of various elements at the time of starting from an accelerator hill hold on an uphill road. 6 is a control map showing an example of a relationship between an oil temperature and a predetermined ratio (ratio of transmission torque to required drive torque). It is a control map which shows an example of the relationship between oil temperature and time limit. 5 is a control map showing an example of the relationship between the input/output rotation difference of the starting frictional engagement element and a predetermined ratio. 5 is a control map showing an example of the relationship between the input/output rotation difference of the starting frictional engagement element and the time limit.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

FIG. 1 is a schematic configuration diagram of a vehicle 1 including a vehicle control device according to an embodiment of the present invention. The vehicle 1 includes an engine 2 as a drive source, an automatic transmission 3 that shifts the output rotation of the engine 2, wheels 4... 4 including drive wheels 4a and 4a, and a braking device 5 for braking the vehicle 1. Is equipped with. 1 shows a so-called vertical power train in which the engine 2 and the automatic transmission 3 are arranged side by side in the longitudinal direction of the vehicle body. However, the power train of the vehicle 1 includes the engine and the automatic transmission. It may be a horizontal type that is arranged side by side in the vehicle body width direction. A motor may be adopted as the drive source instead of the engine, and a hybrid vehicle including both the engine and the motor may be used.

The automatic transmission 3 includes a stepped speed change mechanism, and the speed change mechanism has a plurality of friction engagement elements. The speed change mechanism is configured to form a desired shift speed by selectively engaging a plurality of friction engagement elements. The output rotation of the speed change mechanism is transmitted to the left and right drive wheels 4a, 4a via a propeller shaft and a differential device (not shown).

In the present embodiment, the automatic transmission 3 is configured such that a plurality of (for example, two) friction engagement elements are engaged to form each shift speed. In the following description, of the two friction engagement elements that form the first speed, which is the start gear stage, the friction engagement element that is released while the vehicle is stopped and that is engaged when the vehicle starts is referred to as a start friction engagement element CL.

It should be noted that the first speed, which is the start gear stage, may be formed by the engagement of one friction engagement element and the lock of the one-way clutch. In this case, the one friction engagement element is combined with the start friction engagement element CL. Become.

An engagement hydraulic chamber (not shown) is provided in each friction engagement element, and the hydraulic pressure supplied to the engagement hydraulic chamber is controlled by the hydraulic control device 6 (see FIG. 2). The hydraulic control device 6 controls the flow and hydraulic pressure of the hydraulic oil supplied from the oil pump (not shown) to the hydraulic supply circuit by means of a hydraulic control valve and a switching valve provided in the hydraulic supply circuit. As a result, the hydraulic pressure of the engagement hydraulic chamber of each frictional engagement element is controlled, whereby the engagement, release, and slip of the frictional engagement element and the degree of engagement (engagement ratio) in the slip state are controlled.

The braking device 5 includes a brake pedal 51, a booster 52 that amplifies the pedaling force of the brake pedal 51, a master cylinder 53 that raises the brake fluid pressure in response to a depression operation of the brake pedal 51, and each wheel by the raised brake fluid pressure. 54 for applying a braking force to 4...4, and a hydraulic circuit 55 for connecting the master cylinder 53 and the brake devices 54...54.

The braking device 5 further includes a second braking device 60. The second brake device 60 is provided on the hydraulic circuit 55 between the master cylinder 53 and the brake devices 54...54. The second brake device 60 is composed of, for example, a hydraulic pump (not shown) that uses an electric motor as a drive source, and the second brake device 60 drives the hydraulic pump to drive the hydraulic pressure. The hydraulic pressure of the circuit 55 can be increased. Accordingly, even if the operation of the brake pedal 51 is released, the hydraulic pressure of the brake devices 54... 54 is maintained, and the braking force applied to the wheels 4... 4 is maintained. As the second brake device 60, a DSC (Dynamic Stability Control) device may be used.

As shown in FIG. 2, the control device for the vehicle 1 according to the present embodiment includes a control unit 100 that performs various controls of the vehicle 1. The control unit 100 mainly includes a microprocessor, for example. The control unit 100 includes a central processing unit (CPU), a memory including, for example, a RAM and a ROM, and an input/output interface circuit.

Various external signals used to control the vehicle 1 are input to the control unit 100. Specific examples of the input signal to the control unit 100 include a vehicle speed sensor 71 that detects a traveling speed of the vehicle 1, an accelerator opening sensor 72 that detects an accelerator opening (depression amount of the accelerator pedal), and a rotation speed of the engine 2. The engine speed sensor 73 for detecting, the output speed sensor 74 for detecting the output speed of the transmission mechanism of the automatic transmission 3, the oil temperature sensor 75 for detecting the temperature of the lubricating oil of the starting frictional engagement element CL, and the vehicle 1 are Examples include detection signals from the gradient sensor 76 that detects the gradient of the road surface on which the vehicle is located and the brake pedal sensor 77 that detects the depression of the brake pedal 51.

The oil temperature sensor 75 is provided at an arbitrary position in the transmission case of the automatic transmission 3, for example, a peripheral portion of the starting frictional fastening element CL or an oil storage portion at the bottom of the transmission case.

The control unit 100 includes an engine control unit 110 that controls the engine 2 based on detection values from various sensors including an accelerator opening sensor 72 and an engine speed sensor 73, a vehicle speed sensor 71, an accelerator opening sensor 72, and an engine speed. Shift control means 120 for controlling the shift by outputting a control signal to the hydraulic control device 6 of the transmission 3 based on detection values from various sensors including the number sensor 73 and the output rotation speed sensor 74 of the transmission 3. The vehicle is provided with an uphill braking control means 130 described later.

The uphill road braking control means 130 receives inputs from the vehicle speed sensor 71, the accelerator opening sensor 72, the engine speed sensor 73, the output speed sensor 74 of the transmission 3, the oil temperature sensor 75, the gradient sensor 76, and the brake pedal sensor 77. By outputting a control signal to the hydraulic control device 6 and the second brake device 60 based on the signal, the following uphill braking control is performed.

The uphill road braking control is performed in an accelerator hill hold state (a state in which the required drive torque T1 is larger than zero and the gradient load torque T2 or less) in which an occupant is braking the vehicle 1 by operating the accelerator on an uphill road surface. This control is for maintaining the braking state of the vehicle 1 while suppressing the heat load on the starting frictional engagement element CL. When the uphill road braking control is performed, the starting frictional engagement element CL is held in the slip state so as to avoid the engine stall while transmitting the driving torque to the output side.

In the uphill road braking control according to the present embodiment, the second friction device 60 is actuated to prevent the vehicle 1 from sliding down the uphill road even if the brake pedal 51 is not depressed, and the starting frictional engagement element CL is used. In order to suppress the deterioration due to the heat generation, the slip amount of the starting frictional fastening element CL is reduced.

The uphill braking control is executed when a predetermined uphill braking control condition is satisfied. The uphill road braking control conditions are, for example, that the road surface on which the vehicle 1 is located has an incline having a slope greater than 0%, that the vehicle speed is zero, and that the starting frictional engagement element CL is in a released state (for example, completely released). State), that the brake pedal 51 is turned off, and that the accelerator pedal 70 is turned on.

The uphill braking control means 130 includes a brake control means 131, a required drive torque calculation means 132, a gradient load torque calculation means 133, a fastening force control means 134, a first ratio setting means 135, and a second ratio. The setting means 136, the time limit means 137, and the time limit setting means 138 are provided.

The brake control means 131 automatically actuates the second brake device 60 regardless of the operation of the brake pedal 51. Specifically, the brake control means 131 may actuate the second brake device 60, for example, when the vehicle stops on an uphill road, or immediately after the brake pedal 51 is turned off in a stopped state on an uphill road. The second brake device 60 may be operated when the accelerator pedal 70 is turned on and the required drive torque T1 is equal to or less than the gradient load torque T2 (when the driver has an intention to hold the accelerator hill), or when the vehicle climbs uphill. The second brake device 60 may be operated at the time when the road braking control is started. When the uphill road braking control ends, the brake control means 131 releases the operation of the second braking device 60.

The required drive torque calculation means 132 calculates the required drive torque T1 by the driver based on the accelerator opening detected by the accelerator opening sensor 72.

The gradient load torque calculating means 133 calculates the gradient load torque T2 based on the gradient of the road surface detected by the gradient sensor 76.

The fastening force control means 134 controls the fastening force of the starting frictional fastening element CL in the slip state during execution of the uphill road braking control. Specifically, the fastening force control unit 134 performs the fastening force limiting control for limiting the fastening force of the starting frictional fastening element CL in the uphill braking control. In the engagement force limiting control, the transfer torque TCL (T1×R1) of a predetermined ratio R1 with respect to the required drive torque T1 is used as the starting frictional engagement from the time when the uphill road braking control is started until the predetermined time limit tmax elapses. It is provided with a first limit control for controlling the fastening force so as to be generated by the element CL and a second limit control for further reducing the fastening force after the lapse of the time limit tmax.

The first ratio setting means 135 and the second ratio setting means 136 set the above-mentioned predetermined ratio R1 according to the heat load of the starting frictional fastening element CL. Specifically, the first ratio setting means 135 sets a predetermined ratio R1a according to the oil temperature Te detected by the oil temperature sensor 75, for example, based on the control map shown in FIG. The setting means 136 is a difference (input/output rotation difference) ΔN between the rotational speed of the input side (engine 2 side) rotary element and the output side (drive wheel 4a side) rotary element of the starting frictional engagement element CL. Accordingly, the predetermined ratio R1b is set based on the control map shown in FIG. 7, for example.

In addition, as for the 1st ratio setting means 135 and the 2nd ratio setting means 136, either one of these may be provided and both may be provided. The control maps shown in FIGS. 5 and 7 are stored in advance in a storage unit (not shown) of the control unit 100. Further, the input/output rotation difference ΔN can be calculated, for example, based on the difference between the turbine rotation speed (or engine rotation speed) and the output rotation speed of the transmission 3.

The predetermined ratio R1 (R1a, R1b) is set to be lower as the degree of heat generation of the starting frictional fastening element CL is higher. Specifically, the first ratio setting means 135 sets the predetermined ratio R1a lower as the oil temperature Te is higher, and the second ratio setting means 136 sets the predetermined ratio R1b as the input/output rotation difference ΔN is larger. Set low. One of the predetermined ratio R1a set by the first ratio setting unit 135 and the predetermined ratio R1b set by the second ratio setting unit 136 is selectively selected by the fastening force control unit 134. , Or a combination of both.

As the predetermined ratio R1 (R1a, R1b), after the initial value is set at the start time of the uphill braking control, the degree of increase of the oil temperature Te or the input/output rotation difference ΔN during the execution of the uphill braking control. It may be appropriately corrected according to the degree of increase.

The time limiter 137 sets a predetermined execution time of the first limit control of the engagement force limit control (a time period during which the transmission torque TCL of the starting frictional engagement element CL is maintained at the torque (T1×R1) of a predetermined ratio R1). Is limited to the time limit tmax. When the time limit tmax elapses, the time limiter 137 executes the second limit control (control to further reduce the engaging force of the starting frictional engaging element CL by the engaging force control unit 134), and thereby the starting frictional engagement. Further heat generation of the element CL is suppressed.

The time limit setting means 138 sets the time limit tmax. The time limit setting means 138 sets the time limit tmax to be shorter as the oil temperature Te is higher, based on the control map shown in FIG. 6 and the oil temperature Te at the start of the uphill braking control, for example. However, the time limit setting means 138 may set the time limit tmax according to the input/output rotation difference ΔN instead of the oil temperature Te. In this case, for example, the control map shown in FIG. Based on the input/output rotation difference ΔN at the start of control, the larger the input/output rotation difference ΔN, the shorter the time limit tmax is set.

The control maps shown in FIGS. 6 and 8 are stored in advance in a storage unit (not shown) of the control unit 100.

An example of the operation of the uphill road braking control will be described more specifically with reference to the flowchart of FIG.

In the control operation shown in FIG. 3, while the vehicle is stopped on an uphill road, the engine 2 is driven at an idling speed, the shift range of the automatic transmission 3 is the D range (running range), and the start friction engagement element CL is It is started in a state where the brake pedal 51 is released, the brake pedal 51 is on, the accelerator pedal 70 is off, and the second brake device 60 is operating (see time point t0 in FIG. 4 ).

In step S1 of FIG. 3, it is determined whether the brake pedal 51 is in the released state (off state). When the brake pedal 51 is being depressed (in the ON state), the flow is returned to the beginning, and when it is determined that the brake pedal 51 is in the OFF state, the process proceeds to step S2.

In step S2, it is determined whether the time after the brake pedal 51 is turned off (hereinafter, referred to as "brake off duration time") is a predetermined time Δt1 or less.

If the brake-off duration is longer than the predetermined time Δt1, the process proceeds to step S3 and the second brake device 60 is released. In the following step S4, the state of the accelerator pedal 70 is determined. Until it is determined in step S4 that the accelerator is in the on state (while the accelerator pedal 70 is in the off state), the transmission 3 is in the neutral state and the braking devices 54... 54 are operating on an uphill road with a gradient of greater than 0%. Since there is no vehicle, the vehicle moves down (backs up).

When it is determined in step S4 that the accelerator pedal 70 is in the on state, the process proceeds to step S5, the starting frictional engagement element CL is completely engaged, and the vehicle starts.

On the other hand, in step S2, if the brake-off duration is equal to or less than the predetermined time Δt1, the process proceeds to step S6, and it is determined whether the accelerator pedal 70 is in the on state (the accelerator opening is larger than zero). If it is determined in step S6 that the accelerator pedal 70 is off, the process returns to step S1 until the brake off duration time does not exceed Δt1 (step S2) and it is determined that the accelerator is on (step S2). S6), step S1, step S2, and step S6 are repeated.

In step S6, when it is determined that the accelerator pedal 70 has been stepped on and the accelerator opening degree has become larger than zero, that is, the accelerator pedal 70 is turned on until a predetermined time Δt1 has elapsed after the brake pedal 51 was turned off. When operated, the uphill road braking control is executed in steps S7 to S18.

In step S7, various kinds of information necessary for uphill braking control are detected. In step S7, various detected values such as the accelerator opening, the oil temperature Te, and the gradient are read.

In the following step S8, the driver's required drive torque T1 is calculated based on the accelerator opening. In step S9, based on the oil temperature Te detected in step S7 and the control map shown in FIG. 5, a predetermined ratio (ratio of the transmission torque TCl in the start-stop urine friction engagement element CL to the required drive torque T1). An initial value (for example, 30% to 50%) of R1 (R1a) is calculated. At this time, the transmission torque TCL of the starting frictional engagement element CL corresponds to a value (T1×R1) that is a predetermined ratio R1 to the required drive torque T1 and the transmission torque TCL (T1×R1). The fastening force of the starting frictional fastening element CL is also calculated.

In the following step S10, the time limit tmax relating to the first limit control of the above-mentioned engaging force limit control is calculated based on the oil temperature Te detected in step S7 and the control map shown in FIG.

In step S11, the gradient load torque T2 is calculated based on the gradient of the road surface obtained from the gradient sensor 76. The gradient load torque T2 is a torque that tends to move the vehicle 1 backward by the action of gravity when the vehicle 1 is stopped on an uphill.

Further, in step S11, a start determination torque T3 (T3=T2-ΔT1) (see arrow A1 in FIG. 4) as a lower reference value smaller than the gradient load torque T2 by a predetermined minute amount ΔT1 is also calculated. .. The start confirmation torque T3 is, for example, the required drive torque when the required drive torque T1 increases to such an extent that it can be reasonably determined that it is certain that the driver has stepped on the accelerator pedal 70 with the intention of starting the vehicle. It is set to the size of T1.

Further, in step S11, a startable torque T4 (T4=T2+ΔT2) (see arrow A2 in FIG. 4) as an upper reference value larger than the gradient load torque T2 by a predetermined minute amount ΔT2 is also calculated. The startable torque T4 is set to, for example, the magnitude of the transmission torque TCL at a timing immediately after the transmission torque TCL in the starting frictional engagement element CL exceeds the gradient load torque T2.

In step S12, it is determined whether the required drive torque T1 is less than the start confirmation torque T3 (T3=T2-ΔT1). If the required drive torque T1 is less than the start confirmation torque T3, the process proceeds to step S13. The first limit control of the engagement force limit control is executed. The process of step S13 in the first limit control is repeatedly executed a plurality of times until the time limit tmax set in step S10 elapses.

In step S13 that is first executed, the transmission torque TCL in the starting frictional engagement element CL is in a torque of a predetermined ratio R1 with respect to the required drive torque T1 (T1×R1) according to the initial value of the predetermined ratio R1 calculated in step S9. 4), the fastening force of the starting frictional fastening element CL is controlled (see arrow a in FIG. 4).

In step S14, it is determined whether the elapsed time tCL from when the first limit control is started (when the first step S13 is executed) is equal to or longer than the limit time tmax calculated in step S10. If the elapsed time tCL is less than the time limit tmax, the process proceeds to step S15.

In step S15, the predetermined ratio R1 calculated in step S9 is corrected. The correction in step S15 may be performed based on, for example, one or both of the increase degree of the oil temperature Te and the increase degree of the input/output rotation difference ΔN. In the present embodiment, the correction of the predetermined ratio R1 is based on the degree of increase in the oil temperature Te of the starting frictional engagement element CL detected after the start time of the uphill road braking control (time t1 in FIG. 4). Done.

Then, after the correction in step S15, the process returns to step S12. In step S12 via step S15, it is determined again whether the required drive torque T1 is equal to or less than the start confirmation torque T3. If the required drive torque T1 is equal to or less than the start confirmation torque T3, the process proceeds to step S13 again.

In step S13 after the second time, the fastening force of the starting frictional fastening element CL is controlled according to the predetermined ratio R1 (R1a, R1b) corrected in step S15.

Repeating steps S12 to S15 until the required drive torque T1 rises to the start confirmation torque T3 or more by the determination of step S12, or until the time limit tmax calculated in step S10 elapses by the determination of step S14 1 Limit control is continued.

When the required drive torque T1 becomes equal to or greater than the start confirmation torque T3 in step S12, the process proceeds to step S16, and complete engagement control of the start frictional engagement element CL is executed (see arrow b in FIG. 4).

In the following step S17, it is determined whether or not the transmission torque TCL of the starting frictional engagement element CL is equal to or greater than the startable torque T4 (T4=T2+ΔT2). If the transmission torque TCL is smaller than the startable torque T4, the process returns to step S16. Continue full engagement control.

In step S17, when the transmission torque TCL of the starting frictional engagement element CL is equal to or greater than the startable torque T4, the process proceeds to step S18, and the operation of the second brake device 60 is released. As a result, the starting frictional engagement element CL is completely engaged (arrow c in FIG. 4) and the second brake device 60 is released, so that the vehicle 1 starts (see arrows c and d in FIG. 4).

On the other hand, in step S14, when the elapsed time tCL from the start of the first limit control is equal to or longer than the limit time tmax calculated in step S10 (the limit time before the required drive torque T1 reaches the start confirmation torque T3). When tmax has elapsed) (see time t21 in FIG. 4), the process proceeds to step S19, and the second limit control of the engagement force limit control is executed. That is, in step S19, the fastening force limit control is switched from the first limit control to the second limit control.

Specifically, in the second limit control of step S19, the engagement force of the starting frictional engagement element CL is controlled so as to be further reduced from the time when the first limit control ends. That is, when the second limit control is being performed, the transmission torque TCL of the starting frictional engagement element CL is calculated from the torque (T1×R1) corresponding to the latest predetermined ratio R1 set in step S9 or step S15. Is also reduced (see arrow e in FIG. 4).

In a succeeding step S20, it is determined whether or not the required drive torque T1 is equal to or greater than the start confirmation torque T3. As a result of the determination in step S20, the processes of steps S19 to S20 are repeated and the second limit control is continued until the required drive torque T1 increases to the start confirmation torque T3 or more. While the second limit control is continued, the engaging force and the engaging ratio of the starting friction engaging element CL are maintained in a reduced state (see arrow e in FIG. 4 ).

Then, as a result of the determination in step S20, when the required drive torque T1 reaches or exceeds the start confirmation torque T3, the complete engagement control in step S16 is executed (see arrow f in FIG. 4), and the result of the determination in step S17 is When the transmission torque TCL of the starting frictional engagement element CL reaches or exceeds the startable torque T4, the process proceeds to step S18, and the second brake device 60 is released (see arrow g in FIG. 4). As a result, the starting frictional engagement element CL is completely engaged and the second brake device 60 is released, so that the vehicle 1 starts.

The time chart shown in FIG. 4 shows an example of changes over time of various elements when the vehicle 1 including the control device according to the present embodiment starts from the accelerator hill hold state.

As shown in FIG. 4, at time t0, the second brake device is in a stopped state on an uphill road with a slope greater than 0%, the brake pedal 51 is depressed (brake on), and the brake pedal 51 is not operated. It is assumed that 60 is in an operating state (on state), the accelerator is not operated (accelerator opening is zero), and the engine 2 is driven at an idle speed.

At time t0, the gradient load torque T2 acts on the vehicle 1 located on the uphill road, and the vehicle 1 is in the direction of rolling down. However, due to the brake torque TB of the brake pedal 51 and the second brake device 60, the vehicle 1 is in the stopped state. Has been maintained.

At time t1, the brake pedal 51 is released (turned off), and when the accelerator pedal 70 is turned on at time t2 from the time t1 until a predetermined time Δt1 elapses, the uphill road braking control is started. In the uphill road braking control, first, the first limiting control (step S13 in FIG. 3) of the fastening force limiting control is executed.

When the accelerator pedal 70 is turned on at time t2, the required drive torque T1 increases as the accelerator opening increases. The gradient load torque T2 is higher than the required drive torque T1 when the engagement force limiting control is being performed.

During the engagement force limiting control, the transmission torque TCL of the starting friction engagement element CL is controlled to be a torque (T1×R1) of a predetermined ratio R1 with respect to the required drive torque T1, as shown by an arrow a in FIG. To be done.

Here, a case will be described in which the required drive torque T1 increases until it reaches the start-determined torque T3 from the time when the engagement force limit control is started until the time limit tmax elapses.

When the engaging force limiting control is being executed, the transmission torque TCL and the engaging force of the starting frictional engaging element CL are limited as described above, which causes an excessive deterioration of the starting frictional engaging element CL. Fever can be suppressed.

Further, the predetermined ratio R1 is set with high accuracy based on the actual degree of heat load of the starting frictional engagement element CL (oil temperature Te or input/output rotation difference ΔN), and therefore is set based on prediction. Compared with the case, it becomes easier to suppress the transmission torque TCL and the fastening force of the starting frictional fastening element CL from being excessively reduced, and thus it is easy to suppress an unnecessary decrease in the starting response.

When the required drive torque T1 reaches the start determination torque T3 at the time t3 from the start of the first limit control of the engaging force source control to the elapse of the time limit tmax (see A1 in FIG. 4), The engagement force limitation control ends without switching from the limitation control to the second limitation control, and shifts to complete engagement control (see arrow b in FIG. 4 ).

(Function of inclination of complete fastening)
In the complete engagement control, the time required to match the transmission torque TCL of the starting friction engagement element CL to the required drive torque T1 from the torque (T1×R1) of the predetermined ratio is the engagement (from the neutral to the first speed). It is preferable to set the time to such an extent that the shock due to gear shifting is suppressed and the starting responsiveness of the vehicle is not hindered.

As described above, in the present embodiment, the starting frictional engagement element CL is completely engaged from a state (time point t3) in which the transmission frictional torque TCL having the predetermined ratio R1 with respect to the required drive torque T1 is engaged to some extent. (Time point t4). Therefore, at time t3, it is possible to realize a quick and smooth complete engagement as compared with the case where the complete engagement control is performed after the start friction engagement element CL is completely released. It is possible to improve the sex.

Furthermore, since the starting definite torque T3 that serves as a reference when shifting from the engagement limit control to the complete engagement control is a value T3 (T3=T2-ΔT1) smaller than the gradient load torque T2, the required drive torque T1 is assumed to be the gradient. It is possible to improve the starting response as compared with the case where the complete engagement control is not performed until the load torque T2 is reached (see A3 in FIG. 4).

During the complete engagement control, when the transmission torque TCL of the starting friction engagement element CL reaches a startable torque T4 (T4=T2+ΔT2) larger than the gradient load torque T2 (time point t4), the second brake device 60 is actuated. Is released.

The startable torque T4 is preferably a value that surely exceeds the gradient load torque T2, and the value of ΔT2 does not include zero. As described above, since the operation of the brake devices 54... 54 is released after the actual transmission torque TCL surely exceeds the gradient load torque T2, the vehicle 1 can be surely prevented from sliding down.

When the second brake device 60 is released, the brake hydraulic pressure is released, and at time t5 when the brake torque TB is sufficiently reduced, the output rotation speed and the vehicle speed of the transmission 3 rise and the vehicle starts (arrow in FIG. 4). d)). Although the brake torque TB remains slightly at the time point t5, the brake hydraulic pressure is released gently at the time point t5 to smoothly change the torque.

Next, a case will be described in which, after the engagement force limit control is started, the limit time tmax is reached before the required drive torque T1 reaches the start confirmation torque T3.

In this case, at the time point t21 when the time limit tmax is reached, the fastening force limit control shifts from the first limit control to the second limit control. As a result, the fastening force of the starting frictional fastening element CL is further reduced as compared with the case where the transmission torque TCL of the predetermined ratio R1 with respect to the required drive torque T1 is generated. Therefore, the second limit control is performed from the time t21 after the time limit tmax has elapsed to the time t3 when the complete engagement control is started, so that the heat generation of the starting frictional engagement element CL is more effectively suppressed. You can

After that, similarly to the above, from the time t3 when the required drive torque T1 reaches the starting fixed torque T3, the control shifts to the complete engagement control, and the transmission torque TCL of the starting frictional engagement element CL becomes the startable torque T4 or more. At time point g, the second braking device 60 is released. As a result, the starting frictional engagement element CL is completely engaged and the second brake device 60 is released, so that the vehicle 1 starts.

According to the above configuration, the predetermined ratio R1 and the time limit tmax are appropriately set differently according to the grade of the slope and the heat load of the starting frictional engagement element CL, so that the starting frictional engagement is performed. A balance is achieved between quick fastening of the element CL and reduction of heat load. Therefore, it is possible to always effectively improve both the starting responsiveness and the protection of the starting frictional fastening element CL.

In the above embodiment, an example in which the calculation of the predetermined ratio R1 in step S9 of FIG. 3 and the calculation of the time limit tmax in step S10 are performed based on the oil temperature Te has been described. The calculation may be performed based on other parameters related to the heat load of the element CL. For example, instead of the oil temperature Te, the input/output rotation difference ΔN of the starting frictional engagement element CL may be used for the calculation. Further, the predetermined ratio R1 and the time limit tmax may be calculated based on a plurality of parameters (for example, the oil temperature Te and the input/output rotation difference ΔN).

As described above, according to the present invention, in the vehicle control device, when the vehicle starts from the accelerator hill hold state on an uphill road, it is effective to achieve both protection of the starting frictional engagement element and improvement of the starting responsiveness. Therefore, it may be preferably used in the field of manufacturing industry of vehicles equipped with a transmission having a starting frictional engagement element.

1 vehicle 2 engine (power source)
4...4 Wheels 4a, 4a Drive wheel 51 Brake pedal 54...54 Brake device 60 Second brake device 72 Accelerator opening sensor (accelerator opening detecting means)
73, 74 Engine speed sensor, output speed sensor of transmission (rotation speed difference detecting means)
75 Oil temperature sensor (temperature detection means)
76 Gradient sensor (road surface gradient detection means)
130 Uphill road braking control means 131 Brake control means 132 Required drive torque calculation means 133 Gradient load torque calculation means 134 Engaging force control means 135, 136 First ratio setting means, Second ratio setting means (ratio setting means)
137 Time limit means 138 Time limit setting means CL Start friction engagement element R1 Predetermined ratio T1 Required drive torque T2 Gradient load torque T3 Start confirmation torque (lower reference value)
T4 Startable torque (upper reference value)
TCL transmission torque tmax time limit

Claims (7)

A starting frictional engagement element that is interposed between a power source and a drive wheel to connect and disconnect the power source and the drive wheel,
Fastening force control means for controlling the fastening force of the starting frictional fastening element,
Brake control means for operating the brake device regardless of brake pedal operation,
A road surface slope detecting means for detecting a road surface slope,
Gradient load torque calculating means for calculating a gradient load torque acting on the wheels based on the road surface gradient,
Accelerator opening detection means for detecting the accelerator opening,
A required drive torque calculating means for calculating a required drive torque based on the accelerator opening,
When the road surface is an uphill slope and the required drive torque is larger than zero and is equal to or smaller than the slope load torque, a slope for maintaining the braking state of the vehicle while suppressing the thermal load of the starting frictional engagement element. An uphill road braking control means for executing road braking control, and a control device for a vehicle comprising:
In the uphill road braking control, the uphill road braking control means operates the brake device by the brake control means, while the fastening force control means causes the transfer torque of a predetermined ratio with respect to the required drive torque to be used for the start. A control device for a vehicle, which performs a fastening force limiting control for limiting a fastening force of the starting friction fastening element so as to be generated by the friction fastening element. The uphill road braking control means, when the required drive torque increases to a predetermined lower reference value smaller than the gradient load torque, terminates the fastening force limiting control by the fastening force control means, and The control device for a vehicle according to claim 1, wherein a complete engagement control for completely engaging the start friction engagement element is started. The uphill braking control means causes the brake control means to release the operation of the brake device when the transmission torque in the starting frictional engagement element increases to a predetermined upper reference value that is larger than the gradient load torque. The control device for a vehicle according to claim 1 or claim 2. Temperature detecting means for detecting a temperature related to the temperature of the starting frictional fastening element,
4. The vehicle according to any one of claims 1 to 3, further comprising: ratio setting means for setting the predetermined ratio to be lower as the temperature detected by the temperature detecting means is higher. Control device. During the execution of the fastening force limit control, the time period during which the transmission torque of the starting frictional fastening element is maintained at the torque of the predetermined ratio is limited, and when the limited time period elapses, the fastening force control means controls the torque. Time limiting means for further reducing the fastening force of the starting friction fastening element,
The vehicle control apparatus according to claim 4, further comprising: a time limit setting unit that sets a shorter time limit by the time limit unit as the temperature detected by the temperature detection unit is higher. Rotational speed difference detection means for detecting a difference between the input side rotational speed and the output side rotational speed of the starting frictional fastening element,
The vehicle according to any one of claims 1 to 3, further comprising: ratio setting means for setting the predetermined ratio to be lower as the detected value by the rotation speed difference detecting means is larger. Control device. During the execution of the fastening force limit control, the time period during which the transmission torque of the starting frictional fastening element is maintained at the torque of the predetermined ratio is limited, and when the limited time period elapses, the fastening force control means controls the torque. Time limiting means for further reducing the fastening force of the starting friction fastening element,
The vehicle control device according to claim 6, further comprising: a time limit setting unit that sets a shorter time limit by the time limit unit as the detected value by the rotation speed difference detection unit is larger.

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