JPH11348758A - Vehicle control device - Google Patents

Abstract

(57) [Summary] An object of the present invention is to minimize a response delay when controlling wheels by pump discharge in a device without a pressure storage chamber. SOLUTION: At a stage before execution of this control, standby control for driving a pump and generating a preload is executed.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle control device for controlling the behavior of wheels by a braking torque generated by using a pump discharge pressure.

[0002]

2. Description of the Related Art Conventionally, vehicle acceleration for controlling a slip at the time of acceleration caused by a driving torque given to a driving wheel from at least a power plant system including an internal combustion engine to a desired value by applying a braking torque to the driving wheel. Slip control devices are known. In addition, this type of device has a pressure accumulator for supplying brake pressure by itself, but there is also known a technology for eliminating these auxiliary pressure accumulators and supplying hydraulic pressure only by a pump. (Japanese Patent Laid-Open No. 58
-39971, etc.).

[0003]

However, when the hydraulic pressure is supplied only by driving the pump as described above,
The pressure increase gradient of the brake pressure at the time of the slip reduction control depends on the supply capacity of the pump, and a pump with a low supply capacity may not be able to suppress excessive slip at the beginning of the slip. Further, even if the supply capacity is increased, the response of the slip control is reduced due to the delay of the rising time required for increasing the discharge pressure of the pump, and the pump is also increased in size.

That is, even if the pump drive is started from the time when the acceleration slip is observed, the acceleration slip of the drive wheel becomes excessive within the delay time until the predetermined high pressure value is actually reached. Cannot achieve the purpose of the term. In particular, when starting on a slope, unless the initial acceleration slip is kept small, good starting and acceleration performance cannot be obtained, and the vehicle stability is lost during turning acceleration, which is a serious problem.

Accordingly, the present invention focuses on the delay of the discharge pressure rise time in the initial stage of pump supply, and increases the responsiveness of this control by starting the hydraulic pressure supply by the pump and increasing the pressure before starting this control. It is an object of the present invention to provide a vehicle control device capable of performing the following.

[0006]

To solve the above problems, the present invention has the following arrangement.

According to a first aspect of the present invention, there is provided a vehicle control device comprising: a wheel behavior detecting means for detecting a behavior of the wheel; a pump for applying a braking torque to the wheel; A main control unit for applying a braking torque to a corresponding wheel when detected, and driving the pump based on a standard lower than an execution standard of the main control unit before the main control unit starts. And standby control means for performing the operation.

Therefore, since the pump is driven in the stage before the actual control in which the behavior control is performed by actually applying the braking torque to the wheels, the hysteresis in the actual control is reduced, and the delay of the rising time to the high pressure is suppressed. Therefore, high responsiveness of this control can be ensured.

As specific examples, it is possible to use an acceleration slip suppression control for suppressing the acceleration slip of the wheel as the main control and a means for detecting the acceleration slip state of the wheel as the wheel behavior detecting means. Can compensate for a delay in increasing the wheel cylinder pressure due to pump discharge in the acceleration slip suppression control.

According to a second aspect of the present invention, there is provided a vehicle control device, wherein the main control means applies a braking force to the wheels by discharging the pump, and before the main control means is executed, the pump pressure applied to the wheel cylinder is adjusted. And a standby control unit that starts driving the pump without applying the pressure and generates a preload.

Thus, the same effect as the first aspect can be obtained.

[0012]

Embodiments of the present invention will be described below. FIG. 1 shows the overall system configuration of a front engine / rear drive (FR) type vehicle equipped with the vehicle acceleration slip control device of the embodiment. Hereinafter, the configuration of the acceleration slip control device according to the embodiment will be described with reference to the drawings.

This device detects the rotational speed of the right and left rear drive wheels RR and RL to which the drive torque from the internal combustion engine 6 is transmitted via the transmission 2 and the differential gear 4. Sensors 11, 12;
An electromagnetic pickup type driven wheel speed sensor 1 for detecting the rotational speed of left and right driven wheels FR and FL provided at the front of the vehicle
3, 14; an engine speed sensor 15 for detecting the speed of the internal combustion engine 6; and a shift position sensor 17 for detecting the shift position of the transmission 2 are provided in the driving force transmission system of the vehicle.

The intake system for controlling the output torque of the internal combustion engine 6 includes a main throttle position sensor 24 for detecting an opening of a main throttle 22 interlocked with an accelerator pedal 20, and a sub-throttle actuator 26 comprising a step motor and the like. And a sub-throttle position sensor 30 for detecting the opening degree of the sub-throttle 28 driven by the sub-throttle.

The detection signals from the respective sensors are input to an electronic control circuit 40, where the magnitudes of the braking torque and the driving torque to be applied to the left and right driving wheels RR and RL are determined based on the detection signals of the respective sensors. The control signal according to the determination is output to the brake control device 50 and the sub-throttle actuator 26 described above.

Here, the brake control device 50 controls the drive of the normal brake device provided for each drive wheel RR, RL independently of the left and right. Next, a detailed configuration of the brake control device 50 will be described with reference to FIG. The brake control device 50 controls the control execution signal So output from the electronic control circuit 40 and the left and right driving wheels RL and RR.
Input three kinds of control signals BL and BR,
The normal hydraulic brake devices 50-1 and 50-2 provided on the left and right drive wheels RL and RR are driven based on these signals. The hydraulic brake devices 50-1, 50
-2 is driven by the operating oil pressure obtained by the driver's brake operation in the normal state.
0 in response to various control signals from the hydraulic brake device 5
The oil stored in the reservoir 54 is pumped by the pump 52 to drive 0-1 and 50-2, and constitutes a hydraulic pressure source. The operating hydraulic pressure of each of the hydraulic brake devices 50-1 and 50-2 is generated from the hydraulic pressure of the hydraulic pressure source.

As described above, the brake devices 50-1, 50-
There are two systems of hydraulic pressure sources that drive the motor 2, but in a normal state, the hydraulic pressure source by the driver's operation of the brake pedal is used. That is, the brake oil from the master cylinder MC by the driver's operation of the brake pedal receives the hydraulic line switching valve 58, the left hydraulic control valve 50RL, and the hydraulic line switching valve 5
8 and the right hydraulic control valve 50RR.

Here, the hydraulic line switching valve 58 is a hydraulic source used for driving the hydraulic brake devices 50-1 and 50-2.
Is a two-position valve that switches to a hydraulic pressure source centered on a hydraulic pressure source, and is normally stable at a position where the hydraulic pressure from the master cylinder MC can be supplied to each of the hydraulic brake devices 50-1 and 50-2.
When the control execution signal So is input from the electronic control circuit 40 to the two-position valve drive circuit 60, the position is switched from the stable position over the input period, and the pump 5
Hydraulic brake devices 50-1 and 50
-2 is controlled to a position where it can be driven.

A hydraulic control valve 50 provided on the left and right wheels
RL and 50RR are provided to increase and decrease the braking force of each of the hydraulic brake devices 50-1 and 50-2 by using the hydraulic pressure from the pump 52 transmitted through the hydraulic pipeline switching valve 58. The position valve has a pressure increasing mode a, a pressure reducing mode b, and a holding mode c.

The pressure increase mode a is a mode in which the hydraulic line switching valve 58 communicates with the hydraulic brake devices 50-1 and 50-2, and generates a braking torque corresponding to the amount of brake operation by the driver. This corresponds to time and braking when the braking torque is increased by slip control.

The decompression mode "b" means that the hydraulic brake device 50
This is a mode in which the brake hydraulic pressure is reduced by connecting the low pressure line to the low pressure line. The two-position valve drive circuit 62, which operates in response to the control execution signal So from the electronic control circuit 40, allows the two-position valve 63 to communicate between the low-pressure line that had been shut off and the reservoir 54. Therefore, in the decompression mode b, the hydraulic oil of the hydraulic brake devices 50-1 and 50-2 is returned to the reservoir 54 via the low-pressure line and the two-position valve 63, and the brake hydraulic pressure is reduced.

The holding mode c is a mode in which the above-mentioned various oil passages and the hydraulic brake devices 50-1 and 50-2 are shut off to hold the brake hydraulic pressure. Hydraulic control valves 50RL, 50RR that realize such various modes
Is a three-position valve drive circuit 64 during a slip control period in which the hydraulic pipeline switching valve 58 is switched to the pump 52 side.
Drive control is performed by RL and 64RR in accordance with control signals BL and BR from the electronic control circuit 40.

The three-position valve drive circuits 64RL, 64RR are:
The hydraulic control valve 5 is activated for a period during which the control execution signal So is continuously output from the electronic control circuit 40, and similarly in response to the control signals BL and BR output from the electronic control circuit 40.
Drive control is performed on 0RL and 50RR. In the present embodiment, the hydraulic brake devices 50-1, 50-2 are controlled by a pressure increase or pressure reduction duty ratio D set in accordance with the control signals BL, BR.
Control the increase and decrease of the brake oil pressure. In other words, a time t (t = D ・) for increasing or decreasing the brake hydraulic pressure per a fixed time T in accordance with the control signals BL and BR from the electronic control circuit 40.
T) is determined, and the hydraulic control valves 50RL and 50RR are duty-controlled between modes a and c when the brake hydraulic pressure is increased, and the hydraulic control valve 5 is controlled when the brake hydraulic pressure is reduced.
Duty control of 0RL and 50RR is performed between the modes b and c to control the brake hydraulic pressure of each of the hydraulic brake devices 50-1 and 50-2.

As described above, the brake hydraulic pressure of the hydraulic brake devices 50-1 and 50-2 is controlled to increase or decrease by various control signals from the electronic control circuit 40. In order to improve the control accuracy of the brake hydraulic control, The brake oil pressure of each of the hydraulic brake devices 50-1 and 50-2 is detected by drive wheel brake oil pressure sensors 66 and 68, and the detection result is fed back to the electronic control circuit 40.

Next, an electric circuit configuration centering on the electronic control circuit 40 of this embodiment will be described with reference to FIG. Various sensor detection signals such as the drive wheel speed sensors 11 and 12 as well as the drive wheel brake oil pressure sensors 66 and 68 are input to the electronic control circuit 40, and based on the information, the sub-throttle actuator 26 and the brake control device 50
Various control signals to be output to are determined. The electronic control circuit 40 is constituted by a logical operation circuit for executing such complicated information processing, and the CPU 4 for performing the logical operation.
1, an I / O port 42 serving as an input interface for various sensors, a counter 43 for measuring the number of pulses input from the engine speed sensor 15, a RAM 44 for temporarily storing calculation results, and the like, A ROM 45 storing control data, an I / O port 46 for outputting a control signal to the sub-throttle actuator 26 and the brake control device 50 are provided.

The vehicular acceleration slip control device of the embodiment configured as described above has a ROM 45 of the electronic control circuit 40.
It operates according to the control program stored in. Hereinafter, the operation of the vehicle acceleration slip control device will be described with reference to the flowcharts of the control programs shown in FIGS.

When the acceleration slip control process is started,
First, initialization of the RAM 44 and various initial values are set (step 100). Then, processing (steps 110 to 130) for detecting the current running state of the vehicle by inputting detection signals from various sensors is executed.

In this process, the driven wheel speed sensors 13, 1
4, the driven wheel speeds VPR and VPL are calculated from the detected outputs of the drive wheel speed sensors 4 and 4, and the drive wheel speeds VD and VD are calculated from the detected outputs of the drive wheel speed sensors 11 and 12.
R and VDL are calculated, and the driving wheel speeds VDR and VDL are further calculated.
Then, drive wheel accelerations αDR and αDL are calculated from the time derivative of (step 110).

Then, the vehicle speed VB is estimated based on the driven wheel speeds VPR and VPL (step 120). Here, the vehicle speed VB is calculated, for example, as in the following Expression 1.

[0030]

VB = MAX (VPR, VPL) That is, the larger of the driven wheel speeds VPR, VPL is estimated as the vehicle body speed VB. In addition, a detection signal is input from each of the throttle position sensors 24 and 30 to grasp the current driving state of the vehicle (step 130). Next, it is determined whether or not the acceleration slip control has been started (step 140).
The program proceeds to step 220 to determine whether to end the acceleration slip control. On the other hand, if it is determined in step 140 that the acceleration slip control has not been started, it is determined whether or not an acceleration slip has occurred (step 150). This determination is made, for example, by the following wheel speeds VPR, VPL and the driving wheel speed VDR,
VDL, and the driving wheel speeds VDR and VDL are
When the values exceed PR and VPL by a predetermined amount, the acceleration slip is considered.

If an acceleration slip has occurred (step 150: YES), the flow shifts to the acceleration slip control in step 250 and thereafter. On the other hand, if the acceleration slip has not occurred (step 150: NO), the reference throttle opening is set (step 160). In the previous acceleration slip control, the road surface μ condition was previously determined in step 240.
If the learning has been performed in step (1), the optimum throttle opening for the road surface μ is set as the reference throttle opening. Also,
For example, when the information from the previous acceleration slip control cannot be obtained, for example, when the ignition is turned on for the first time, the full throttle opening may be set as the reference throttle opening.

Next, it is determined whether or not the pump drive (hereinafter, referred to as standby control) for predicting the occurrence of the acceleration slip is being executed (step 170). 170: YES), and proceeds to standby control end determination processing in step 200 described later.

When not in standby control (step 1)
70: NO), that is, it is determined whether or not to start the standby control for the first time when it is determined that neither the acceleration slip control nor the standby control is performed in the processing up to step 170 (step 180).

As a specific determination method, the reference throttle opening which is determined in step 160 and reflects the road surface μ information and which is the optimum throttle opening in the road surface state, and the reference throttle opening detected in step 130, The actual throttle opening at the calculation timing is compared with the actual throttle opening. If the actual throttle opening exceeds the reference throttle opening, the standby control is started by predicting that an acceleration slip will occur when the output of the internal combustion engine responds to the throttle opening. In step 190, the process proceeds to step 190 to start driving the pump 52.

On the other hand, if it is determined in step 170 that the standby control has already been started, it is determined whether or not the standby control end condition has been satisfied (step 200). This determination is made based on, for example, whether or not a predetermined time has elapsed since the start of the standby control.
Alternatively, the determination may be made based on whether or not the throttle opening detected in step 130 exceeds a predetermined value.

If the condition for terminating the standby control is not satisfied in step 200, the process returns to step 110 and the following processing is repeated. If the condition for terminating the standby control is satisfied, the drive of the pump 52 is terminated (step 200). 210), and return to step 110. Here, in order to further improve the responsiveness at the start of the acceleration slip control, the hydraulic pipeline switching valve 58 may be turned on and off in accordance with the pump drive at the start and end of the standby control. However, in this case,
During the standby control, it is necessary to switch the hydraulic control valves 50RL and 50RR to the holding mode c.

Next, the acceleration slip control after step 250, which is performed when it is determined in step 150 that an acceleration slip has occurred, will be described. First, it is determined whether or not the standby control is currently being executed (step 250). If not, the pump 52 is started to be driven, and the hydraulic line switching valve 58 and the two-position valve 63 are respectively operated. Turn on (step 26)
0).

Then, the current slip state is determined based on various wheel speed information, and the hydraulic control valves 50RL, 50R
The drive pattern of R is determined. Specifically, a plurality of threshold values for the driven wheel speeds VPR and VPL are set in advance, and based on which threshold the drive wheel speeds VDR and VDL are between,
The pressure increase / hold / decompression pattern of predetermined several stages is determined.

When the acceleration slip control is being executed, in step 240, the current road surface condition is determined from the slip state during the acceleration slip control, the brake oil pressure generated in the drive wheels RL and RR, the throttle opening, and the like. To learn. In this embodiment, a state in which the drive wheel speeds VDR, VDL are within the range of the driven wheel speeds VPR, VPL + predetermined value is defined as a stable region, and the drive torque estimated value based on the throttle opening at that time and the brake hydraulic pressure The road surface μ is learned from the difference from the braking torque estimation value based on. As a result, an equivalent result can be obtained simply by using the throttle opening at the end of the acceleration slip control. It should be noted that the road surface μ learning value in this case can be represented by the throttle opening.

The determination of the end of the acceleration slip control performed in step 220 when the acceleration slip control is being performed in the determination in step 140 will be described. This end determination is made based on the throttle opening or various wheel speeds. In this embodiment, the acceleration slip control is performed when either the throttle opening is fully closed or the drive wheel speeds VDR, VDL fall below the driven wheel speeds VPR, VPL + predetermined value for a predetermined time. To end.

However, when the end condition based on the throttle opening is satisfied, the acceleration slip control for the left and right drive wheels RL and RR is simultaneously ended. Drive wheels RL, RR
End determination is performed individually, and is not affected by the state of the target wheel.

Next, the periodic interruption processing shown in FIG. 6 will be described. This periodic interruption processing is performed by the hydraulic control valve 5.
This is a process for actually driving 0RL and 50RR. Based on the pressure increase / hold / pressure reduction pattern determined in step 230, the three-position valve drive circuits 64RL and 64R
The hydraulic control valves 50RL and 50RR are driven by R to control the brake hydraulic pressure of each of the hydraulic brake devices 50-1 and 50-2 (step 300). The reason for performing the periodic interruption process is to control the pressure increase / decrease pressure gradient by using a combination of the pressure increasing / holding / pressure decreasing time duty ratio D by using a three-position valve for the hydraulic pressure control valves 50RL and 50RR.

As described above, according to the acceleration slip control device of the present embodiment, the reference throttle opening at which the occurrence of acceleration slip is predicted is set according to the road surface μ, and the detected throttle opening is set at the reference throttle opening. When the opening degree is exceeded, even before the start of the acceleration slip control, the pump 52
Is driven to increase the discharge pressure in advance.

Therefore, when slip is predicted, the pump discharge pressure is increased in advance by standby control. When slip actually occurs, further increase in pressure is started from the preload level.
The delay of the rising time required for increasing the discharge pressure of the liquid crystal can be compensated.

In order to clarify the effect of the acceleration slip control of this embodiment, the difference between the two depending on the presence or absence of the standby control will be described with reference to a time chart shown in FIG. In FIG. 7, the solid line indicates the case with standby control, and the dashed line indicates the case without standby control (that is, the conventional one). As can be seen from the figure, when the throttle opening in (a) exceeds the reference throttle opening, that is, when the occurrence of slip is predicted, standby control is started, and as shown in (c), the pump discharge pressure is reduced. It is driven and pressure is increased in advance.

Then, as shown in (b), when the driving wheel speed exceeds the acceleration slip determination threshold value and the acceleration slip control is executed, in (c), further pressure increase is started from the preload level. The rise time required until the discharge pressure of the pump 52 is increased is shortened.
Therefore, the pressure increase gradient of the brake pressure is also steep and reaches the predetermined level quickly. Accordingly, the response of the acceleration slip control is improved as shown in FIG. 2B, and good starting and acceleration performance can be secured.

In the above-described embodiment, no special sensor is used for detecting the road surface condition. However, the road surface condition is detected by using a ground sensor or the like for detecting the road surface μ, and the optimum road surface condition is determined in advance. The reference throttle opening may be set with reference to a map of the throttle opening. In the above-described embodiment, the acceleration slip is predicted based on the throttle opening. However, a threshold smaller than the threshold used for detecting the acceleration slip is set, and the standby control is performed when the driving wheel speeds VDR and VDL exceed the threshold. May be started.

On the other hand, a reference rotation speed for predicting the acceleration slip is set by using the rotation speed of the internal combustion engine instead of the throttle opening, and when the engine rotation speed exceeds this reference rotation speed, the standby control is started. Even if it comprises, it can implement similarly. Further, in the above embodiment, the reference throttle opening is set according to the detected road surface condition, and the start timing of the standby control is determined by comparing the detected actual throttle opening with the reference throttle opening. But
Another method will be described below.

Based on the throttle opening and the amount of change in the throttle opening, an evaluation value S1 is calculated as in the following equation 2, and if this evaluation value exceeds a predetermined reference evaluation value FS1, standby control is performed. You may make it start.

[0050]

S1 = KA.times.THM + KB.times..DELTA.THM, where KA.sub.KB; coefficient THM; throttle opening .DELTA.THM; change in throttle opening. S2 is calculated, and a predetermined reference evaluation value F is calculated.
The present invention can be similarly implemented by comparing with S2 or calculating the evaluation value S3 using the engine speed and the amount of change in the engine speed and comparing with the predetermined reference evaluation value FS3. Generally, the throttle opening, the engine speed, and the wheel speed are more useful as a predicted drive torque value in the order named. That is, the response delay is large in this order.

In the present acceleration slip control device, since the pump 52 is driven, the pump 52 and the hydraulic line switching valve 58 or the hydraulic control valves 50RL, 50RR are switched during the period from the standby control to the acceleration slip control. There is a risk that the piping between them may become high pressure. As a countermeasure, a pressure regulating valve (not shown) may be provided in the middle of the corresponding pipe in addition to a method of forcibly terminating a predetermined time or more after the start of the standby control as shown in steps 200 and 210. In the case where a pressure equal to or more than a predetermined value is generated by interposing the oil, the excess oil may be returned to the reservoir 54.

In this embodiment, the main throttle 22
In addition to the above description, the configuration including the sub throttle 28 is described as an example, but the sub throttle 28, the sub throttle actuator 26, the sub throttle position sensor 3
A configuration having no 0 can be similarly implemented.

As described above, according to the present invention, this control is used as an acceleration slip control device for a vehicle, and if a slip is predicted, the pump is driven in advance before this control to increase the pump discharge pressure. By increasing the pressure, when the slip actually occurs, the pressure increase starts from the preload level, so the rise time required for increasing the pump discharge pressure in the wheel cylinder pressure increase in this control is increased. Can compensate for the delay of
This has the effect of increasing the responsiveness of the acceleration slip control and ensuring good starting and acceleration performance.

[Brief description of the drawings]

FIG. 1 is a configuration block diagram of a vehicle system equipped with a vehicle acceleration slip control device according to one embodiment of the present invention.

FIG. 2 is a configuration explanatory diagram mainly showing a hydraulic system of a brake control device of the present embodiment.

FIG. 3 is a block diagram illustrating an electric system according to the present embodiment.

FIG. 4 is a first half of a flowchart showing an acceleration slip control process of the present embodiment.

FIG. 5 is a second half of a flowchart showing the acceleration slip control process.

FIG. 6 is a flowchart showing a periodic interruption process.

FIG. 7 is a time chart illustrating acceleration slip control according to the present embodiment.

[Explanation of symbols]

RL, RR: drive wheels, MC: master cylinder,
6 ... internal combustion engine, 11 ... drive wheel speed sensor, 1
3 ... driven wheel speed sensor, 15 ... engine speed sensor,
20: accelerator pedal, 22: main throttle,
24 ... Main throttle position sensor, 2
8 ... sub throttle, 30 ... sub throttle position sensor, 40 ... electronic control circuit,
50: brake control device, 50RL, 50RR: hydraulic control valve, 52: pump, 58: hydraulic line switching valve

Claims (3)

[Claims] 1. A vehicle control device for controlling the behavior of a vehicle body by applying a braking torque generated by using a pump discharge pressure to wheels of the vehicle, wherein a wheel behavior detecting means for detecting the behavior of the wheel; A pump for applying a braking torque to the wheel; a control unit for applying a braking torque to a corresponding wheel when the wheel behavior detecting unit detects a behavior that is equal to or greater than a predetermined value; And a standby control unit that drives the pump based on a criterion lower than the execution criterion of the control unit before the control unit starts. 2. A vehicle control device for controlling the behavior of a vehicle body by applying a braking torque generated using a pump discharge pressure to wheels of a vehicle, wherein a braking force is applied to the wheels by the pump discharge. Vehicle control characterized by comprising: a main control unit that performs the main control unit; and a standby control unit that starts driving of the pump without applying pump pressure to the wheel cylinders to generate a preload before the execution of the main control unit. apparatus. 3. The control device according to claim 2, wherein the standby control unit changes a reference value for determining a timing at which the standby control is to be performed before the execution of the main control unit, according to a road surface condition under the wheel. The vehicle main control device according to claim 1 or 2.