CN103661356A - Vehicle control apparatus - Google Patents

Abstract

A vehicle control device, comprising: when an engine (11) mounted on a vehicle (10) is restarted, an engaged state of an engaging element of a transmission (12) is maintained and a braking force is applied to a wheel (13). an interlock control means (7); an engine driving force calculating means (3) for calculating an engine driving force generated by the engine (11); and a braking force calculating means for calculating a braking force generated by a brake device (14) of the vehicle (10) (4). The interlock control means (7) calculates and generates an interlock holding force based on the difference between the engine driving force and the braking force. In addition, the interlock control means changes the timing of releasing the interlock according to the ambient temperature related to the braking force of the brake device provided on the wheel. In addition, the interlock control means (7) changes the timing of releasing the interlock according to the ambient temperature related to the braking force of the brake device (14) provided on the wheel (13).

Description

vehicle control device

technical field

The present invention relates to a vehicle control device that controls a braking force generated by interlocking a transmission mounted on a vehicle.

Background technique

Conventionally, a hill start assist device is known as a device for suppressing the vehicle from sliding down when starting on a hill. It is a device that temporarily holds the brake hydraulic pressure immediately after the brake pedal is released when starting the vehicle. By switching from the brake pedal to the accelerator pedal while the hill start assist device maintains the brake hydraulic pressure, the vehicle can be started smoothly while suppressing unintended vehicle forward and reverse.

However, the braking force applied to the gears with the hill start assist device corresponds to the hydraulic pressure of the brakes. Therefore, if the gradient of the slope on which the vehicle stops is steep, the slide cannot be prevented unless the brake hydraulic pressure is maintained to increase the braking force. In addition, in a vehicle that uses the control of the hill start assist device and the idling stop control (automatic stop and automatic restart control according to the engine load) at the same time, the driving force at the time of restarting the engine may temporarily increase suddenly and exceed the braking force. , the behavior of the vehicle after starting is sometimes unstable.

Therefore, a technology has been proposed that utilizes the interlock function of the transmission to reduce the amount of driving force transmitted from the engine to the wheels within the transmission, thereby reducing the load on the hill start assist device. The interlock function mentioned here refers to the function of intentionally forming a double mesh state (interlock) by engaging a frictional engagement element not located on the power transmission path from the engine to the wheels inside the transmission. When the interlock occurs, the output from the transmission decreases, and the magnitude of the output corresponds to the tightening pressure of the frictional engagement elements. Therefore, by using both the hill start assist device and the interlock function of the transmission, braking performance immediately after the wheels start can be improved (for example, refer to Patent Document 1).

Patent Document 1: Japanese Patent Laid-Open No. 2010-6326

The problem to be solved by the invention

The magnitude of the braking force applied to the vehicle by the hill start assist device can vary depending on the operating conditions of the vehicle, environmental conditions, individual differences in characteristics of the braking device, and the like. For example, when the temperature of the brake fluid is high, the brake fluid pressure tends to decrease due to a decrease in viscosity, and the period during which the brake fluid pressure is maintained by the hill start assist device tends to be shortened. On the contrary, when the temperature of the brake fluid is low temperature, the holding period of the brake hydraulic pressure tends to be prolonged. In addition, such brake characteristics are not only affected by the temperature of the brake fluid, but also may be affected by individual differences and aging.

However, in the conventional technology described in Patent Document 1, since such brake characteristics are not taken into consideration, the braking force after the vehicle moves forward may be excessive or the driving force may be insufficient, and the acceleration of the vehicle may be significantly reduced. In particular, in a vehicle that uses hill start assist control and idle stop control at the same time, the timing of the sudden increase of the engine driving force and the timing of the brake hydraulic pressure drop do not necessarily coincide, so it is easy to produce a hooking or flying feeling when starting. It is difficult to maintain the driving stability of the vehicle.

Contents of the invention

One object of the present invention is to provide a vehicle control device capable of improving the running stability of a vehicle, created in view of the above problems. In addition, it is not limited to this object, and it can also serve as another object of the present invention as an effect brought about by each configuration shown in the form for carrying out the invention described later, that is, exerting an effect that cannot be obtained by conventional techniques.

means to solve the problem

(1) The vehicle control device of the present invention has: an interlock control member that maintains the engagement state of the engagement elements of the transmission and applies a braking force to the wheels when the engine mounted on the vehicle is restarted; an engine driving force calculating means for the generated engine driving force; and a braking force calculating means for calculating a braking force generated by the brake device of the vehicle, the interlock control means, based on the engine driving force and the braking force The difference is calculated and produces the interlock retention force.

The brake device includes a brake device that applies a braking force to a wheel in response to a driver's depressing operation on a brake pedal, or a device that automatically applies a braking force to a wheel regardless of whether the brake pedal is depressed. For example, the brake device includes a hill start assist device for suppressing the vehicle from sliding down when starting on a hill. The specific braking method of the brake device is arbitrary, for example, there are friction brakes, electric brakes and fluid brakes.

In addition, the transmission mentioned here is a transmission that at least has the function of reducing the driving force input from the engine and then outputting it to the wheel side, for example, it is a transmission that has a plurality of frictions built in the transmission. A transmission that functions to engage frictional engagement elements that are not located on the power transmission path among the elements. When the frictional engagement elements that are not on the power transmission path are engaged, a double mesh state (so-called interlock state) is formed, and the output from the transmission decreases. The magnitude of this output corresponds to the tightening pressure of the engaged frictional engagement elements. The interlock holding force is a force corresponding to the output reduction portion.

(2) In addition, the vehicle control device preferably has target driving force calculating means for calculating the target driving force of the vehicle. In this case, it is preferable that the interlock control means correct the interlock holding force calculated from the difference between the engine driving force and the braking force based on the target driving force. For example, preferably, the interlock control means subtracts the target driving force calculated by the target driving force calculating means from the difference between the driving force and the braking force and the target driving force. force, while controlling the interlock retention force.

(3) In addition, it is preferable that, when the difference between the engine driving force and the braking force is less than the target driving force, the interlock control means corrects the interlock holding force so as to increase the When the difference between the engine driving force and the braking force is equal to or greater than the target driving force, the interlock control means corrects the interlock maintaining force so that Decreases the rate at which the interlock retention force decreases. In other words, preferably, after comparing the difference between the driving force and the braking force with the target driving force, if the former is smaller than the latter, then increase the release speed of the interlock holding force, and if the former is larger than the latter , then reduce the opening speed.

(4) Further, preferably, the target driving force calculation means calculates the target driving force based on a road surface gradient. In this case, it is preferable that the target driving force be increased and the interlock holding force be decreased as the road surface gradient is an upward slope as the inclination increases. As a result, the actual driving force transmitted to the wheels increases, and the climbing speed increases. In addition, it is preferable that, if the gradient of the road surface is downhill, the target driving force is decreased and the interlock holding force is increased the greater the inclination. As a result, the actual driving force transmitted to the wheels decreases, and the downhill speed decreases. In addition, it is preferable that at least the road surface gradient is reflected in the control of the interlock holding force. Therefore, the interlock control means can also control the interlock holding force according to the road surface gradient.

(5) In addition, it is preferable that the interlock control means change the timing of releasing the interlock in accordance with an ambient temperature related to a braking force of a brake device provided on the wheel.

The transmission mentioned here is a transmission that at least has the function of reducing the driving force input from the engine and then outputting it to the wheel side, for example, it is a transmission that has a plurality of frictional engagement elements built into the transmission. A transmission that does not engage with friction elements on the power transmission path. When the frictional engagement elements that are not on the power transmission path are engaged, a double mesh state (so-called interlock state) is formed, and the output from the transmission decreases. The magnitude of this output corresponds to the tightening pressure of the engaged frictional engagement elements. The force corresponding to this output reduction is called interlock holding force.

The "time when the interlock is released" mentioned here includes the time when the interlock holding force generated by the transmission starts to be released, and the time when the release of the interlock holding force ends (the time when the interlock holding force becomes zero) . Considering the application time of the braking force estimated from the ambient temperature, the time point at which the interlock control member maintains the force for releasing the interlock is controlled.

The so-called ambient temperature mentioned here is, for example, the temperature (the temperature reflected by the characteristics of the brake fluid) that affects the characteristics (fluidity, viscosity, etc.) of the brake fluid that drives the brake device. Specifically, it includes: Fluid temperature, outside air temperature, vehicle interior temperature, and the temperature of the reservoir tank after sealing the brake fluid, etc. In contrast to the correlation between the ambient temperature and the braking force, the ambient temperature can be used to evaluate the influence (size) and impact time (effectiveness) of the braking force.

In addition, the brake device includes a brake device that applies a braking force to a wheel in response to a driver's depressing operation on a brake pedal, or a device that automatically applies a braking force to a wheel regardless of whether the brake pedal is depressed. For example, it includes a hill start assist device for suppressing the vehicle from sliding down when starting on a hill. . The specific braking method in the brake device is arbitrary, and there are, for example, friction brakes, electric brakes, and fluid brakes.

(6) In addition, it is preferable that the interlock control means delays the time point of releasing the interlock as the ambient temperature becomes higher. That is, it is preferable that the interlock holding force is less likely to be lost in a state where the braking force is more likely to be lost. As a result, the braking force in which the braking force is attenuated is replaced by the interlock holding force.

(7) In addition, it is preferable that the interlock control means changes the timing at which the interlock is released after the engine is restarted from the idling stop state.

The effect of the invention

According to the vehicle control device of the present invention, the interlock holding force is controlled according to the difference between the engine driving force and the braking force of the brake device, so that the wheel driving force can be suppressed even when the output of the engine and the braking force vary. Changes transmitted to the wheel side. Thereby, it is possible to suppress the feeling of hooking and jumping out when the vehicle is started, and improve the running stability of the vehicle.

With the vehicle control device of the present invention, by controlling the opening time point of the interlock holding force according to the ambient temperature related to the braking force, even when the magnitude (effectiveness) of the braking force changes, the wheel can be restrained. Changes in drive force transmission to the wheel side. Accordingly, it is possible to suppress the feeling of hooking and jumping out when the vehicle is moving forward, and improve the running stability of the vehicle.

Description of drawings

FIG. 1 is a schematic diagram illustrating the configuration of a vehicle control device according to an embodiment.

FIG. 2 is a flowchart illustrating a control procedure of the gear control device.

Fig. 3 is a time chart for explaining the control action of the vehicle control device, Fig. 3(a) is the vehicle speed, Fig. 3(b) is the driving force of the engine, Fig. 3(c) is the braking force, and Fig. 3(d) is the speed change Figure 3(e) is the interlock holding force, Figure 3(f) is the wheel driving force, and Figure 3(g) is the acceleration of the car body.

Symbol Description

1...vehicle control device, 2...calculation section, 3...engine drive force calculation section (engine drive force calculation means), 4...braking force calculation section (braking force calculation means), 5...target drive force calculation Part (target driving force calculation means), 6 ... interlock holding force calculation part (interlock control means), 7 ... transmission control part (interlock control means), 10 ... vehicle, 11 ... engine, 12 ...speed changer, 14...wheel brake (brake device).

Detailed ways

The vehicle control device will now be described with reference to the drawings. In addition, the embodiment shown below is only an illustration after all, and it is not intended to exclude various deformation|transformation and technical application which are not expressly shown in the following embodiment. The structures of the present embodiment can be modified in various ways without departing from their gist, and can be selected or combined as necessary.

(1. Device Configuration) FIG. 1 is a block diagram showing a schematic configuration of a vehicle 10 to which a vehicle control device according to the present embodiment is applied. The output work of the engine 11 mounted on the vehicle 10 is transmitted to the wheels 13 through the transmission 12 . The transmission 12 is a transmission having a function of changing the wheel driving force transmitted to the wheel 13 side by controlling the fastening force of a plurality of frictional engagement elements (clutch elements, brake elements).

In the case of the transmission 12 having a planetary gear mechanism, the magnitude of the wheel drive force is controlled by engaging frictional engagement elements that are not located on the power transmission path to intentionally create a double mesh (interlock) state. Alternatively, the magnitude of the wheel driving force can also be controlled by increasing the fastening force of the element acting to stop the rotational motion among the frictional engagement elements located on the power transmission path. The transmission 12 not only has the function of changing the speed of the rotation of the output shaft of the engine 10 but also has at least a function of reducing the driving force transmitted from the engine 11 .

Hereinafter, the braking force (transmission holding force) generated inside the transmission 12 is referred to as "interlock holding force". For a specific control method of the frictional engagement element, known techniques such as those described in Patent Document 1 can be applied. In addition, when the electric transmission oil pump is mounted on the vehicle 10 , the fastening force of the frictional engagement elements can be controlled regardless of the operating state of the engine 11 . On the other hand, in the case of the vehicle 10 having the transmission oil pump operated by the driving force of the engine 11, the fastening force of the frictional engagement elements immediately after the engine 11 is started may not be ensured.

Therefore, wheel brakes 14 (brake devices) connected to a hydraulic unit 15 are provided on the wheels 13 . The hydraulic unit 15 has two functions.

The first function is to cause the wheel brakes 14 to generate a braking force corresponding to normal brake operation. Accordingly, a brake hydraulic pressure P (oil pressure) corresponding to the stepping operation of the brake pedal 16 is generated inside the hydraulic unit 15, and the brake hydraulic pressure P is transmitted to the wheel brakes 14, and a braking force corresponding to the magnitude of the brake hydraulic pressure P acts on the wheels 13. superior.

The second function is to automatically generate a braking force for suppressing the vehicle from sliding down when starting on a hill. For example, when the road surface gradient is large when the vehicle is stopped, the brake hydraulic pressure P is maintained at a predetermined value or higher irrespective of fluctuations in the amount of depression of the brake pedal 16, and at the same time, the hydraulic pressure P is delayed immediately after the brake pedal 16 is released. Descending, slowly reducing the braking force acting on the wheel 13. This control is also known as hill start assist or uphill assist function. Hereinafter, the braking force generated in the wheel brake 14 corresponding to the brake fluid pressure P is referred to as "braking force".

The vehicle control device 1 is provided on the vehicle 10 described above. The vehicle control device 1 is configured by connecting integrated large-scale integrated circuit devices such as a microprocessor, ROM, and RAM, and built-in electronic devices to a communication line of an on-vehicle network provided in the vehicle 10 . In the vehicle control device 1 , the states of the engine 11 , the transmission 12 and the wheel brakes 14 are controlled.

As shown in FIG. 1 , the vehicle control device 1 is connected with: a speed sensor 21 for detecting the engine speed Ne; a wheel speed sensor 22 for detecting the vehicle speed V (wheel speed); and a brake hydraulic pressure P for the hydraulic unit 15. The brake hydraulic sensor 23 for detection; the accelerator opening sensor 24 for detecting the accelerator opening APS; the slope sensor 25 for detecting the road surface slope θ; and the brake fluid temperature sensor 26 for detecting the brake fluid temperature T (environmental temperature) wait. In the vehicle control device 1 , based on information detected by these various sensors 21 to 26 , idling stop control, hill start assist control, and driving force correction control are executed.

(2. Contents of Control) The idling stop control is control that automatically temporarily stops and restarts the engine 11 in accordance with the stop and start of the vehicle 10 . The conditions for starting the idling stop control are, for example, detection that the brake pedal 16 is depressed and the vehicle speed V is substantially zero. On the other hand, the end condition of the idling stop control is detection that the brake pedal 16 is not stepped on or that the accelerator opening APS (acceleration pedal depression operation) is greater than or equal to a predetermined value.

The hill start assist control is a control for suppressing the vehicle from sliding down when starting on a hill using the latter of the two functions of the hydraulic unit 15 . The conditions for starting the hill start assist control are, for example, that the vehicle speed V is substantially 0 (the vehicle 10 is stopped) and the absolute value of the road surface gradient θ exceeds a predetermined value θ0. Thus, when the vehicle 10 temporarily stops on a certain level of uphill or downhill, the brake hydraulic pressure P automatically continues to act on the wheel brakes 14 for a period of time after the brake pedal 16 is released, thereby suppressing the vehicle 10 from sliding down. .

The so-called driving force correction control is a control to correct the wheel driving force output from the transmission 12 to the wheels 13 immediately after the vehicle 10 starts to improve the running stability and driving feeling when the vehicle starts. In this control, for example, the deviation of the effective side of the braking force due to the hill start assist control, the deviation of the engine driving force when the engine 11 is started, the fluctuation of the target driving force set in response to the driver's start request and acceleration request, etc. , to adjust the interlock holding force in the transmission 12.

The driving force correction control of the present embodiment is executed when the vehicle 10 is started when returning from the idling stop control. In addition, the magnitude of the interlocking holding force can be controlled by changing the degree of fastening force of the frictional engagement elements, and the specific method of changing the degree of fastening is arbitrary. Next, the contents of the driving force correction control will be described in detail.

(3. Vehicle Control Device) The vehicle control device 1 is provided with a calculation unit 2 and a transmission control unit 7 . These elements may be realized by circuits (hardware), or may be programmed software, or some of these functions may be hardware and other parts may be software.

The purpose of the calculation unit 2 is to calculate various parameters related to the driving force correction control. Here, as shown in FIG. 1 , an engine driving force calculating unit 3 , a braking force calculating unit 4 , a target driving force calculating unit 5 , and an interlock holding force calculating unit 6 are provided.

The purpose of the engine driving force calculating unit 3 (engine driving force calculating means) is to calculate the engine driving force A generated by the engine 11 . Here, the engine drive force A is calculated from the engine speed Ne and the accelerator opening APS. In addition, when the vehicle 10 has an engine ECU, a control structure may be adopted that reads the engine driving force A calculated by the engine ECU. The information on the engine driving force A obtained here is transmitted to the interlock holding force calculation unit 6 .

The purpose of the braking force calculating unit 4 (braking force calculating means) is to calculate the braking force B generated by the wheel brake 14 . Here, the braking force B is calculated based on, for example, the brake fluid pressure P detected by the brake fluid pressure sensor 23 and the brake fluid temperature T detected by the brake fluid temperature sensor 26 . Therefore, the braking force B includes not only the braking force for hill start assist but also the braking force generated by stepping on the brake pedal 16 . Information on the braking force B calculated here is transmitted to the interlock holding force calculation unit 6 .

The state of the brake fluid temperature T is reflected in the braking force B calculated here. For example, the higher the brake fluid temperature T is, the smaller the braking force B is, or the calculation is performed to increase the gradient of the braking force B. Conversely, the lower the brake fluid temperature T is, the larger the braking force B is, or the calculation is performed so that the gradient of the braking force B decreases. In this way, the information on the brake fluid temperature T is used to grasp the characteristics related to the easiness of extinction of the braking force.

The purpose of the target driving force calculating unit 5 (target driving force calculating means) is to calculate the target driving force C which is a target value of the driving force required by the vehicle 10 . The target driving force C is a driving force for smooth starting and running of the vehicle 10, and is calculated from the engine speed Ne, the accelerator opening APS, and the road surface gradient θ. The value of the target driving force C is calculated, for example, to increase as the road surface gradient θ increases (inclined upward), and to decrease as the road surface gradient θ decreases (inclined downward). Information on the target driving force C calculated here is transmitted to the interlock holding force calculation unit 6 .

The purpose of the interlock holding force calculation unit 6 (interlock control means) is to calculate the interlock holding force D generated by the transmission 2 . The interlock holding force D is calculated from the difference between the engine driving force A and the braking force B. Here, the calculation method in the case of controlling the change gradient of the interlock holding force D and the calculation method in the case of controlling the magnitude will be described.

In the case of controlling the change gradient of the interlock holding force D, the interlock holding force D is set to a preset initial holding force D0 when the vehicle 10 starts, and at the same time, the subsequent release of the interlock holding force D The speed ΔD (interlock release speed) is calculated from the difference between the engine driving force A and the braking force B. For example, when the difference (A-B) between the engine driving force A and the braking force B is smaller than the target driving force C, the opening speed ΔD per unit time of the interlock holding force D is corrected to increase. This correction corresponds to an operation of increasing the reduction speed of the interlock holding force D. FIG. On the other hand, when the difference (A-B) between the engine driving force A and the braking force B is equal to or greater than the target driving force C, the opening speed ΔD is corrected to decrease. This correction corresponds to an operation of reducing the reduction speed of the interlock holding force D. FIG.

In addition, the opening speed ΔD may be controlled according to the brake fluid temperature T. For example, the lower the brake fluid temperature T, the more the opening speed ΔD is corrected to increase, and the higher the brake fluid temperature T, the more the release speed ΔD is corrected to decrease. In addition, the state of the brake fluid temperature T is already reflected in the braking force B calculated by the braking force calculating unit 4 in the present embodiment.

In the case of controlling the magnitude of the interlock holding force D, the interlock holding force D when the vehicle 10 is started is calculated by, for example, Equation 1 below. In this case, when the target driving force C is constant, the interlock holding force D changes according to the difference between the engine driving force A and the braking force B. That is, the interlock holding force D is calculated from the difference between the engine driving force A and the braking force B. In addition, focusing on the relationship with the target driving force C, the interlock holding force D is a value corrected based on the target driving force C after being calculated from the difference between the engine driving force A and the braking force B. Information on the interlock holding force D calculated here is transmitted to the transmission control unit 7 .

D=A-B-C...(Formula 1)

The purpose of the transmission control unit 7 (interlock control means) is to control the frictional engagement elements inside the transmission 12 based on the interlock holding force D calculated by the interlock holding force calculation unit 6 and its release speed ΔD. Solid force controls. That is, the transmission control unit 7 controls to apply a braking force to the wheels 13 while maintaining the engagement state of the frictional engagement element with the transmission 12 . Here, it is conceivable to implement two types of control corresponding to the two types of calculation methods related to the interlock holding force D. FIG.

The first method is: increase the fastening pressure of the frictional engagement elements until the interlocking holding force D when the vehicle 10 starts reaches the initial holding force D0, after the interlocking holding force D reaches the initial holding force D0, according to the The release speed ΔD calculated by the holding force calculation unit 6 and corrected reduces the tightening pressure of the frictional engagement elements. In this case, for example, when the target driving force C is greater than the value (A-B), the fastening speed and the releasing speed of the interlock are delayed, and when the target driving force C is smaller than the value (A-B), the fastening speed and the releasing speed of the frictional engagement element are accelerated. open speed.

The state where C>(A-B) holds is that the driving force obtained by subtracting the braking force B from the engine driving force A is slightly smaller than the target driving force C. In this case, the interlock holding force D such as that of the transmission 12 should be absorbed, the fastening speed and release speed of the frictional engagement elements should be reduced, and the acting time of the interlock holding force D should be prolonged. On the other hand, the state where C<(A-B) holds true is when the driving force obtained by subtracting the braking force B from the engine driving force A is greater than the target driving force C. In this case, the action time of the interlock holding force D should be shortened, and the tightening and releasing speeds of the frictional engagement elements should be increased.

In addition, when the brake fluid temperature T is considered, the higher the brake fluid temperature T is, the lower the viscosity of the brake fluid is, and the shorter the application time of the braking force B is. Therefore, in this case, the action time of the interlock holding force D should be prolonged and the release time of the interlock should be delayed, thereby reducing the tightening speed and releasing speed of the frictional engagement elements. Conversely, if the brake fluid temperature T is low, the action time of the interlock holding force D should be shortened to increase the fastening speed and release speed of the frictional engagement elements.

The second method is to control the fastening force of the frictional engagement elements so that the transmission 12 generates a braking force equal to the interlock holding force D calculated by the interlock holding force calculation unit 6 . In this case, the actual interlock holding force D becomes larger as the engine driving force A increases, and becomes smaller as the engine driving force A decreases. On the other hand, take the opposite action with respect to the change of the braking force B and the target driving force C, for example, the more the braking force B increases, the more the actual interlock holding force D is reduced, the more the braking force B decreases, The actual interlock holding force D increases more.

The control using the first method can be regarded as a control that increases or decreases the time during which the interlock holding force D acts. On the other hand, the control using the second method can be regarded as the control of increasing or decreasing the magnitude of the interlocking holding force D. In either case, the magnitude of the wheel drive force output from the transmission 12 to the wheels 13 is optimized, and the running stability and driving feeling at the time of starting the vehicle are improved.

(4. Flowchart) FIG. 2 is a flowchart illustrating the procedure of the driving force correction control executed in the vehicle control device 1 . Here, a flow when the control of increasing or decreasing the time in which the interlock holding force D acts is performed is exemplified.

In step A10, it is determined in the vehicle control device 1 whether or not a condition for starting the idling stop control is satisfied. Here, if the start condition of the idling stop control is satisfied, the process proceeds to step A20, and if not satisfied, the flow of the calculation cycle ends.

In addition, in step A20, it is determined whether or not the start condition of the hill start assist control is satisfied. For example, it is determined whether the absolute value of the road surface gradient θ exceeds a predetermined value θ0. Here, if the start condition of the hill start assist control is satisfied, the process proceeds to step A30 to start the hill start assist control. In this case, the brake hydraulic pressure P generated according to the depression amount of the brake pedal 16 is maintained, and the process proceeds to step A40. On the other hand, if the start condition of the hill start assist control is not satisfied, the process proceeds to step A40 as it is.

In step A40, idling stop control is implemented. In this step, the fuel supply to the engine 11 is cut off, and the engine 11 is stopped. In the next step A50, it is determined whether or not the end condition of the idling stop control is satisfied. For example, if it is detected that the brake pedal 16 is not released, the end condition of the idling stop control is satisfied, and the process proceeds to step A60. On the other hand, when the end condition is not satisfied, the control returns to step A40, and the idling stop control is continued.

In step A60, fuel supply to the engine 11 is restarted, and the engine 11 is automatically restarted. In the next step A70, the target driving force calculation unit 5 calculates the target driving force C based on the engine speed Ne and the road surface gradient θ. In addition, in step A80 following it, the interlock holding force D is set to a preset initial holding force D0 , and a control signal corresponding to the initial holding force D0 is output from the vehicle control device 1 to the transmission 12 . As a result, the fastening force at which the initial holding force D0 is obtained inside the transmission 12 is set as a target value, the fastening pressure of the frictional engagement elements rises, and the interlock holding force D gradually increases.

Furthermore, in step A90, it is determined whether or not the engine speed Ne exceeds a predetermined start-up speed Ne0. Here, if Ne>Ne0 holds, the process proceeds to step A100. On the other hand, if the determination condition in step A90 is not satisfied, the control returns to step A60, and the starting operation of the engine 11 is continued.

In step A100, it is determined whether the change amount ΔNe per unit time of the engine speed Ne is smaller than a predetermined steady gradient value ΔNe0, and if ΔNe<ΔNe0 holds, the process proceeds to step A110. On the other hand, if the determination condition in step A100 is not satisfied, the control returns to step A60, and the starting operation of the engine 11 is continued.

In step A110 , the interlock holding force D is controlled such that the interlock holding force D decreases by a predetermined opening speed ΔD0 set in advance. In this step, a control signal corresponding to the predetermined opening speed ΔD0 is output from the vehicle control device 1 to the transmission 12 . As a result, the fastening pressure of the frictional engagement elements decreases, and the interlock holding force D gradually decreases.

In step A120 , the target driving force C is calculated by the target driving force calculating unit 5 . Here, the target driving force C is calculated from the engine speed Ne, the accelerator opening APS, and the road surface gradient θ, and the target driving force C is corrected according to the driver's intention to start. In the next step A130, the engine driving force calculation unit 3 calculates the engine driving force A from the engine speed Ne and the accelerator opening APS. In addition, in step A140 , the braking force B is calculated from the brake hydraulic pressure P by the braking force calculation unit 4 .

In step A150, it is determined whether or not the target driving force C is greater than the difference (A-B) between the engine driving force A and the braking force B. When the determination condition is satisfied, it is determined that the driving force actually transmitted to the wheel 13 side is greater than the target driving force C (that is, the state where the braking force B is sufficiently large) and proceeds to step A160, where the interlocking holding force D is released. The speed ΔD is corrected in the increasing direction. On the other hand, if the determination condition of step A150 is not satisfied, it is determined that the actual driving force is smaller than the target driving force C (that is, the braking force B is insufficient) and the process proceeds to step A170, and the release speed ΔD of the interlock holding force D is increased to The decreasing direction is corrected.

In these steps A160 and A170 , a control signal corresponding to the corrected opening speed ΔD is output from the vehicle control device 1 to the transmission 12 . As a result, the acting time of the interlock holding force D is appropriately adjusted, and the magnitude of the wheel driving force output from the transmission 12 to the wheel 13 side is optimized. In addition, in step A180, it is determined whether the magnitude of the interlock holding force D is 0 or less. Here, in the case of D≦0, this flow ends, and the driving force correction control ends. On the other hand, in the case of D>0, control returns to step A110, and the opening speed ΔD is controlled until the interlock holding force D becomes 0.

In addition, the above-mentioned flowchart is a diagram for controlling the action time of the interlock holding force D. FIG. In contrast, in the case of controlling the magnitude of the interlock holding force D, it is only necessary to change step A80 and steps A150 to A170. For example, if the interlock holding force D is controlled when the tightening pressure of the frictional engagement element is reduced, such a control structure is conceivable: in step A150, the interlock holding force D is calculated according to formula 1, and the corresponding The control signal is output from the vehicle control device 1 to the transmission 12 .

In this case, steps A160, A170 may be omitted. Similarly, such a control structure can also be made: if the interlock holding force D is controlled when the fastening pressure of the frictional engagement element is increased, the interlock holding force D is calculated in step A80, and the corresponding control signal Output from the vehicle control device 1 to the transmission 12 .

In addition, when the brake fluid temperature T is reflected in the control of the interlock holding force D, before step A170 of the above-mentioned flowchart, the interlock holding force may be increased or decreased according to the brake fluid temperature T. The step of correcting the opening speed ΔD of the force D. In addition, if the interlock holding force D is controlled when the fastening pressure of the frictional engagement elements is increased, the initial holding force D0 can be corrected according to the brake fluid temperature T in step A80, or it can be increased or decreased. The tightening speed of the interlock holding force D is corrected.

(5. Operation) FIGS. 3( a ) to ( g ) show time charts for explaining the control operation of the vehicle control device 1 from when the vehicle 10 is stopped to when it starts. Time t1 is the time after the brake pedal 16 of the traveling vehicle 10 is stepped on to stop, and time t2 is the time when the start condition of the idling stop control is satisfied. In addition, the interlock holding force D shown in FIG. 3( e ) represents fluctuations in the holding force in the transmission 12 having a transmission oil pump operated by the driving force of the engine 11 .

When the idling stop control is started, as shown in FIG. 3( b ), the engine driving force A decreases as the engine 11 is stopped. At this time, the state of the clutch incorporated in the transmission 12 is switched from the forward state to the interlocked state as shown in FIG. 3( d ).

When the absolute value of the road surface gradient θ exceeds the fixed value θ0 while the vehicle 10 is stopped, the hill start assist control is started. As a result, the brake hydraulic pressure P corresponding to the brake depression force is held in the wheel brakes 14 . Then, when the brake pedal 16 is released at time t3, as shown by the dotted line in FIG. 3(c), the brake pedaling force decreases. However, since the braking force B indicated by the solid line is maintained for a while after the brake pedal 16 is released, the vehicle 10 is suppressed from sliding down. In addition, when the end condition of the idling stop control is satisfied by releasing the brake pedal 16, the start operation of the engine 11 is started, and at the same time, the driving force correction control is started.

The hill start assist control ends at time t4 after a predetermined time has elapsed from time t3, and then the braking force B decreases. Here, as shown by the solid line in Figure 3(c), if the brake fluid temperature T is high and the braking force B decreases rapidly, the difference (A-B) between the engine driving force A and the braking force B will rise rapidly, that is , the difference (A-B) is relatively easy to become larger than the target driving force C.

Therefore, the releasing speed ΔD of the interlocking holding force D is easily corrected to decrease, and as shown by the solid line in FIG. That is, the lost part of the braking force B is supplemented by the interlock holding force D. Therefore, as shown by the solid line in FIG. 3( f ), the wheel driving force transmitted from the transmission 12 to the gear 13 side increases smoothly. In addition, the acceleration of the vehicle body does not change rapidly as shown by the solid line in FIG. 3( g ), and the feeling of jumping out of the vehicle 10 can be suppressed.

On the other hand, as shown by the dotted line in Fig. 3(c), when the brake fluid temperature T is low and the braking force B decreases slowly, the difference (A-B) between the engine driving force A and the braking force B increases slowly, That is, the difference (A-B) is relatively easy to become small with respect to the target driving force C. FIG. Therefore, the releasing speed ΔD of the interlocking holding force D is easily corrected in the increasing direction, as shown by the dotted line in FIG. That is, in a state where the braking force B is difficult to decrease, the interlock holding force D decreases rapidly, and the driving force transmitted to the wheel 13 side does not become excessively large, thereby suppressing the feeling of hooking. The wheel driving force and the acceleration of the vehicle body fluctuate substantially in the same manner as when the braking force B decreases rapidly, as indicated by the solid lines in FIGS. 3(f) and (g).

In addition, even if the decrease speed of the braking force B is fast, when the accelerator pedal is depressed immediately after the idling stop control is completed, the driver's start request is reflected in the target driving force C, and the engine driving force A and the braking force B The difference (A-B) with respect to the target driving force C is relatively easy to become small.

Therefore, the opening speed ΔD of the interlocking holding force D is easily corrected in the direction of increasing. As shown by the dotted line in Fig. The graph is shortened. That is, the driving force transmitted from the transmission 12 to the wheels 13 increases at an early time. Therefore, as shown by the dotted line in Fig. 3(f) and (g), the wheel driving force and the acceleration of the vehicle body rapidly increase according to the driver's intention to start, and the acceleration responsiveness of the vehicle 10 improves.

(6. Effects) (1) In this way, with the above-mentioned vehicle control device 1, since the interlock holding force D is controlled based on the difference (A-B) between the engine driving force A and the braking force B, even in the magnitude of the braking force B Even in the case where the action time is changed, the sudden change of the driving force transmitted to the wheel 13 side can be suppressed. Therefore, the running stability of the vehicle can be improved.

(2) In addition, in the vehicle control device 1 described above, the interlock holding force D is controlled based on not only the difference (A-B) between the engine driving force A and the braking force B but also the target driving force C. Accordingly, the behavior of the vehicle 10 can be controlled according to the road surface gradient θ and the driver's intention to start, and the running stability and acceleration responsiveness when the vehicle is moving forward can be improved.

(3) In particular, in the vehicle control device 1 described above, since the release speed ΔD of the interlock holding force D is controlled based on the magnitude relationship between the difference (A-B) between the engine driving force A and the braking force B and the target driving force C, , can properly handle the driver's intention to start and the interlock holding force D (for example, the implementation time of the driving force correction control and the action time of the interlock holding force D, the magnitude of the interlock holding force D, etc.), and the vehicle can be improved. driving stability and acceleration responsiveness.

(4) In addition, in the vehicle control device 1 described above, the target driving force C is calculated from the road surface gradient θ. For example, when traveling on a steep slope, the calculated value of the target driving force C is larger than that when traveling on a flat road, and the interlock holding force D decreases rapidly, so the wheel driving force increases earlier. Therefore, the effect of suppressing slipping and flying out when the vehicle is moving forward can be enhanced.

(5) In addition, in the vehicle control device 1 described above, the interlock holding force D at the time of returning from the idling stop control is controlled by the driving force correction control. Thereby, it is possible to appropriately suppress the unstable fluctuation of the driving force due to the unstable rotation after the engine 11 is restarted, and it is possible to improve the running stability of the vehicle.

(6) Furthermore, in the vehicle control device 1 described above, the interlock holding force D is controlled by the drive force correction control even when the idling stop control and the hill start assist control are used simultaneously. As a result, even when the rising timing of the engine driving force A does not coincide with the falling timing of the braking force B, the interlock holding force D can be applied appropriately, and the running stability of the vehicle can be improved.

(7) In addition, in the vehicle control device 1 described above, the application time of the interlock holding force D is controlled using the braking force B calculated from the brake fluid temperature T. For example, if the brake fluid temperature T is low, the calculation of increasing the braking force B or decreasing the gradient of the braking force B is performed, so that the interlock holding force D is relatively reduced or the interlock holding force D is released. The speed ΔD is corrected to increase. On the other hand, if the brake fluid temperature T is high, calculations are performed to decrease the braking force B or increase the gradient of the braking force B. Therefore, it is controlled so that the interlock holding force D becomes relatively large, or the interlock holding force The opening speed ΔD of D is corrected to decrease.

In this way, by controlling the interlock holding force D based on the brake fluid temperature T, the viscosity of the brake fluid can be appropriately evaluated, and the characteristics of the braking force B can be grasped with high precision (for example, the braking force B from the moment the brake pedal 16 is released The descending speed), which can be reflected as the control of the interlocking holding force D. Therefore, the running stability of the vehicle can be improved regardless of the magnitude (effectiveness) of the braking force B.

(8) In addition, the higher the brake fluid temperature T is, the lower the viscosity of the brake fluid is, and the braking force B disappears earlier. On the contrary, in the vehicle control device 1 described above, since the timing of release is delayed by controlling the interlock holding force D, the insufficient part of the braking force B can be supplemented by the interlock holding force D. Therefore, the running stability of the vehicle can be improved without applying excessive or insufficient braking force to the engine drive force A when the vehicle starts.

(9) In addition, in the vehicle control device 1 described above, for example, when the release speed ΔD of the interlock holding force D is corrected in the direction of decreasing as the brake fluid temperature T becomes higher, the interlock holding force D is extended. Substantial application period. As a result, even when the braking force B disappears in a short time, the braking force against the engine driving force A can be ensured when the vehicle is started, thereby improving the running stability of the vehicle.

(7. Modification) In the above-mentioned embodiment, the driving force correction control is performed when the vehicle 10 is started when returning from the idling stop control, but the timing of carrying out the driving force correction control is not limited to this. For example, not only when returning from the idle stop control, but also when the vehicle 10 is started, the driving force correction control may be performed all the time, or the driving force correction control may be performed when the vehicle 10 is running at a slow speed (for example, slow running) and normal running. In any case, the same operations and effects as those of the above-described embodiment are obtained.

In addition, in the above-mentioned embodiment, the interlock holding force D and its release speed ΔD were exemplified as the control objects, but the fastening speed of the interlock holding force D may be controlled in addition to or instead of this control structure. Object, the period during which the interlock holding force D is applied is the control object. For example, it can be considered that when the target driving force C is greater than the value (A-B), the interlock fastening speed is corrected to increase, and when the target driving force C is below the value (A-B), the tightening speed is decreased. Correction. In the former case, the interlock holding force D rapidly becomes large, and as a result, the interlock holding force D is strengthened. On the other hand, in the latter case, since the interlock holding force D gradually increases, the interlock holding force D is weakened as a result.

In addition, it may be considered that when the target driving force C is greater than the value (A-B), the application period of the interlock holding force D is extended, and when the target driving force C is below the value (A-B), the application period of the interlock holding force D is extended. shorten. In the former case, the interlock holding force D acts for a long time, that is, the interlock holding force D is strengthened. In contrast, in the latter case, the interlock holding force D is weakened. In this way, by processing the strength of the braking force B and the strength of the interlock holding force D in a complementary manner, the same operations and effects as those of the above-described embodiment are obtained.

In the above-mentioned embodiment, the interlock holding force D is controlled according to the magnitude relationship between the difference (A-B) between the engine driving force A and the braking force B and the target driving force C, but the specific control method is not limited thereto. For example, the interlock holding force D can also be calculated according to the above formula 1, and the interlock state of the transmission 12 is controlled so that the holding force actually generated by the transmission 12 is consistent with (or close to) the calculated value of the interlock holding force D .

Alternatively, the interlock holding force D may be controlled based on the brake fluid temperature T detected by the brake fluid temperature sensor 26 . In this case, it is conceivable that the lower the brake fluid temperature T is, the lower the interlock holding force D is, or the release speed ΔD is corrected to increase. Conversely, it may be considered that the higher the brake fluid temperature T is, the more the interlock holding force D is increased, or the release speed ΔD is corrected to decrease.

That is to say, it is controlled according to the brake characteristics that change with the brake fluid temperature T: in the state where the braking force is easy to fade, it is supplemented with the interlock holding force D, and in the state where the braking force is difficult to fade, the interlock is not activated. The retention force D is excessive. For example, as the brake fluid temperature T becomes high, the time to release the interlock (time to start release of the interlock holding force D, time to end release, etc.) is delayed. In this control as well, the same action and effect as in the above-mentioned embodiment are obtained.

In addition, in the above-mentioned embodiment, the brake fluid temperature T is used to calculate the braking force B, and the interlock holding force D is controlled accordingly, but the outside air temperature, the vehicle interior temperature, etc. may be used instead of the brake fluid temperature T. If at least the ambient temperature confirmed to be relevant to the braking force B is used, the same operations and effects as those of the above-described embodiment are obtained.

Claims (7)

1. A vehicle control device, characterized in that it has: An interlock control member that maintains the engagement state of the engagement elements of the transmission and applies braking force to the wheels when the engine mounted on the vehicle is restarted; engine driving force calculating means for calculating the engine driving force generated by the engine; and a braking force calculating means for calculating a braking force generated by the brake device of the vehicle, The interlock control means calculates and generates an interlock holding force based on a difference between the engine driving force and the braking force. 2. The vehicle control device according to claim 1, further comprising target driving force calculating means for calculating a target driving force of the vehicle, The interlock control means corrects the interlock holding force calculated from the difference between the engine driving force and the braking force based on the target driving force. 3. The vehicle control device according to claim 2, wherein when the difference between the engine driving force and the braking force is less than the target driving force, the interlock control means controls the interlock. Lock holding force is corrected to increase the reduction speed of the interlock holding force, When the difference between the engine driving force and the braking force is equal to or greater than the target driving force, the interlock control means corrects the interlock holding force so as to reduce a decrease in the interlock holding force. speed. 4. The vehicle control device according to claim 2 or 3, wherein the target driving force calculating means calculates the target driving force based on a road surface gradient. 5. The vehicle control device according to claim 1, wherein: The interlock control means changes the timing of releasing the interlock according to the ambient temperature related to the braking force of the brake device provided on the wheel. 6. The vehicle control device according to claim 5, wherein the interlock control means delays a time point of releasing the interlock as the ambient temperature becomes higher. 7. The vehicle control device according to claim 5 or 6, wherein the interlock control means changes the timing at which the interlock is released after the engine is restarted from the idling stop state.

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