JP3212670B2 - Vehicle slip control device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle slip control device for preventing a drive wheel from slipping excessively on a road surface when the vehicle starts or accelerates. The present invention relates to a so-called brake traction control fail countermeasure for suppressing the slip.

[0002]

2. Description of the Related Art In slip control (also referred to as traction control) for preventing excessive slip of drive wheels on a road surface at the time of starting or accelerating a vehicle, a braking force is forcibly applied to the drive wheels. There are brake control and engine control for controlling the output of the engine, and these two types of slip control are usually used together. For example, JP-A-60-
Japanese Patent Application Laid-Open No. 128028/1990 discloses that the engine control is started when the rotational speed difference between the left and right driving wheels becomes equal to or more than a predetermined value. When the slip value is small, only the engine control is performed, and when the slip value of the drive wheel is large,
It discloses that both the engine control and the brake control are performed.

[0003] Conventionally, as a control device for performing the above-mentioned brake control, in addition to a device for applying a braking force to a drive wheel using a hydraulic pressure generated by a hydraulic pump, a master cylinder is driven by a brake booster to drive the drive wheel. There is known a device that applies a braking force to a vehicle. As disclosed in, for example, Japanese Patent Publication No. 3-5344, this type of control device includes a master cylinder that supplies brake fluid pressure to a wheel cylinder of a driving wheel and a driven wheel, a wheel of the master cylinder and a wheel of the driven wheel. A first opening / closing valve provided in a brake pipe between the cylinder and a first chamber and a second chamber defined by a movable wall connected to the master cylinder; A negative pressure is always introduced into the second chamber, while a negative pressure is usually introduced into the second chamber, and an atmospheric pressure is introduced when the brake pedal is depressed. A brake booster that drives the master cylinder in accordance with the pressure, a second on-off valve provided in a path for introducing the negative pressure to the second chamber, and a second chamber that is operated by the brake booster. Independent of pressure adjustment An adjusting valve provided so as to be adjustable to a state where the negative pressure and the atmosphere are introduced into the second chamber; a plurality of wheel speed detecting means for detecting rotation speeds of driving wheels and driven wheels; and a wheel speed detecting means. And control means for controlling the first and second opening / closing valves and the regulating valve in response to a signal from the controller. Then, the control means normally keeps both the on-off valves in the open state and the regulating valve in the shut-off state, while the difference in rotation speed between the drive wheel and the driven wheel is larger than a predetermined value. In the case of, while switching the above both on-off valve to the closed state,
By controlling the operation of the regulating valve, a differential pressure is generated between the first chamber and the second chamber to forcibly drive the brake booster. At this time, the supply of the brake fluid pressure to the wheel cylinders of the driven wheels is shut off by the first on-off valve, so that the fluid pressure generated in the master cylinder acts only on the wheel cylinders of the drive wheels, and the slip of the drive wheels is reduced. Is suppressed.

[0004]

The negative pressure introduced to the brake booster is usually the negative pressure of the intake air of the engine (see Japanese Patent Publication No. Hei 3-5344 described above).

On the other hand, in a vehicle engine, the intake valve of the engine is closed at a relatively late point from the bottom dead center in the compression stroke in order to improve fuel efficiency and the like. In some cases, a supercharger is provided to supply the intake air by pressure.However, in this type of engine, the intake negative pressure is not so high because the throttle valve is set to be slightly open even when the throttle valve is fully closed. No. In addition, even with a normal engine, when the vehicle travels in a place with a low atmospheric pressure such as high altitude, the intake negative pressure becomes low. When the intake negative pressure is low as described above, if the intake negative pressure is used as a negative pressure for operating the brake booster, the brake traction control is hindered.

Therefore, in order to solve such a problem, a vacuum pump is provided, and the negative pressure generated by the vacuum pump is used together with the intake negative pressure as a negative pressure for operating the brake booster, or used alone. It is possible. However, even when the vacuum pump fails, if the brake traction control is continued for a long time, a negative pressure shortage occurs, which hinders normal brake braking.

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, and an object of the present invention is to provide a vacuum pump as a negative pressure generating source for operating a brake booster as described above. To provide a vehicle slip control device capable of ensuring brake braking.

[0008]

In order to attain the above object, according to the present invention, when a driving wheel is in a slip state, a master cylinder is driven by a brake booster to apply a braking force to the driving wheel. In the vehicle slip control device configured as described above, a vacuum pump that generates a negative pressure introduced into the brake booster, a pump failure detection unit that detects a failure of the vacuum pump, and a failure of the vacuum pump is detected by the detection unit. Regulating means for regulating the application of a braking force to the driving wheel when detected, wherein the regulating means
During the control in which the braking force is being applied to
When a failure of the volume pump is detected,
Controlling the application of braking force when you have finished
The configuration is provided .

[0009]

According to the above-mentioned structure, according to the first aspect of the present invention,
When the vacuum pump fails, the pump failure detecting means detects the failure, and the regulating means receiving a signal from the detecting means regulates the application of the braking force to the drive wheels, that is, the brake traction control. As a result, the negative pressure of the brake booster is secured without being consumed by the brake traction control, and the brake booster operates normally during normal brake braking.

Further, upon detection of a failure of the vacuum pump in the middle of the brake traction control, since the subsequent brake traction control at the time the control is finished is regulated, behavior of the vehicle is due to a rapid regulation of the brake traction control It can prevent instability .

[0011]

Embodiments of the present invention will be described below with reference to the drawings.

In FIG. 1, 1FL denotes a front left wheel, 1FR denotes a front right wheel, 1RL denotes a rear left wheel, and 1RR denotes a rear right wheel. Reference numeral 2 denotes an engine mounted horizontally on the front part of the vehicle body. The generated torque of the engine 2 is sequentially transmitted to the clutch 3, the transmission 4 and the differential device 5, and then the left drive shaft 6L
Via the left front wheel 1FL and the right drive shaft 6R
To the right front wheel 1FR. As described above, in the vehicle, the front wheels 1FL, 1FR are used as drive wheels, and the rear wheels 1RL, 1RL are used.
1RR is a front wheel drive vehicle that is a driven wheel.

An intake valve (not shown) of each cylinder of the engine 2 is set so as to close at a relatively late point in time from the bottom dead center of the compression stroke. A supercharger 18 is provided downstream of the valve 17 (cylinder side of the engine 2). The main throttle valve 17 has an opening degree of the accelerator pedal 1.
It is provided so as to correspond to the depression amount of No. 9 and to be slightly opened when fully closed.

Further, 7FL, 7FR, 7RL and 7RR
Is a brake mounted on each of the wheels 1FL to 1RR, and each of the brakes 7FL to 7RR is a disc brake having a hydraulic wheel cylinder 7a. 8
Is a master cylinder as a brake fluid pressure source, which is a tandem type having two discharge ports 8a and 8b. A brake pipe 13 extends from one discharge port 8 a of the master cylinder 8.
Is branched into two on the way. One branch pipe 13F is the wheel cylinder 7 of the left front wheel brake 7FL.
a, and the other branch pipe 13R is connected to the wheel cylinder 7a of the right rear wheel brake 7RR. A brake pipe 14 extends from the other discharge port 8b of the master cylinder 8, and the brake pipe 14 is also branched into two, and one branch pipe 14F is connected to the wheel cylinder 7a of the right front wheel brake 7FR. The other branch pipe 14R is connected to the wheel cylinder 7a of the left rear wheel brake 7RL.

The four branch pipes 13F, 13R, 14
F, 14R, branch pipe 1 for front wheels, that is, for drive wheels
3F and 14F are provided with electromagnetic hydraulic control valves 15L and 15L, respectively.
15R, a branch pipe 1 for a rear wheel, that is, for a driven wheel.
3R and 14R have electromagnetic on-off valves 16L and 16L, respectively.
R is connected. The hydraulic control valves 15L, 15R
Is a pressure increasing position for supplying brake fluid pressure (oil pressure) from the master cylinder 8 to the wheel cylinders 7a of the brakes 7FL and 7FR to increase the pressure in the wheel cylinders 7a, and the brake fluid pressure in the wheel cylinders 7a. To the reserve tanks 22L, 22R via the pipes 21L, 21R.
The pressure is switched to the decompression position where the pressure is reduced. The brake fluid stored in the one reserve tank 22L is supplied by the hydraulic pump 23L through the pipe 25L provided with the check valve 24L and the brake pipe 13 at a pressure equal to or higher than the hydraulic pressure in the pipe 13. The master cylinder 8
And sent back. Similarly, the other reserve tank 2
The brake fluid stored in the 2R is also fed back to the master cylinder 8 by the hydraulic pump 23R via the brake pipe 14 and the pipe 25R provided with the check valve 24R.

Further, reference numeral 12 denotes a brake pedal,
The depression force of the brake pedal 12 is transmitted to the master cylinder 8 via a booster, that is, a brake booster 11. The brake booster 11 is basically the same as a known vacuum booster. However, in the case of slip control, as described later, the brake booster 11 has a boosting action even when the brake pedal 12 is not depressed. Is configured to do so.

The brake booster 11 has a case 31 fixed to the vehicle body and the master cylinder 8, and a first chamber 34 in the case 31 is formed by a diaphragm 32 and a valve body 33 fixed thereto. And the second
A chamber 35 is defined. The first chamber 34 is always supplied with a negative pressure. When the brake pedal 12 is not depressed, the second chamber 35 is communicated with the first chamber 34, and the operation of the brake booster 11 is stopped. On the other hand, when the brake pedal 12 is depressed, the atmospheric pressure is supplied to the second chamber 35, whereby the diaphragm 32 is displaced forward together with the valve body 33, and a boosting action is performed.

The negative pressure supplied to the first chamber 34 is the negative pressure generated by the vacuum pump 39 driven by the engine 2 and the negative pressure of the throttle valve 1 in the intake passage 20 of the engine 2.
The suction negative pressure guided from the portion between the turbocharger 7 and the supercharger 18 is used in combination. Although not shown, the negative pressure supply passage prevents the backflow of the negative pressure in the first chamber 34. A check valve is provided. The switching between the negative pressure supply and the atmospheric pressure supply to the second chamber 35 is basically performed by a valve device provided in the valve body 33. The valve body 33 will be described with reference to FIG.

That is, in FIG.
3 is a power piston 4 fixed to the diaphragm 32
1 and a recess 41 formed in the power piston 41
The reaction disk 42 and the base end of the output shaft 43 are fitted in a. The output shaft 43 serves as an input shaft of the master cylinder 8. A valve plunger 45 is mounted in the valve body 33 at the tip of the input shaft 44 connected to the brake pedal 12. A vacuum valve 46 is provided behind the valve plunger 45.

A pressure introduction passage 50 is formed in the power piston 41, and the pressure introduction passage 50 is always communicated with a space 51 formed around the valve plunger 45. The space 51 is always in communication with the second chamber 35. A valve seat 47 on which the vacuum valve 46 is seated is formed at an open end of the pressure introduction passage 50 toward the space 51. The vacuum valve 46 is also seated on a valve seat 45a formed at the rear end of the valve plunger 45. Reference numerals 48 and 49 denote springs for urging the vacuum valve 46 in a direction for seating the same on the valve seat 45a.

In the above configuration, it is assumed that a negative pressure is introduced into the pressure introducing passage 50. In this state, when the brake pedal 12 is not depressed, the vacuum valve 46 is seated on the valve seat 45a by the urging force of the springs 48, 49 in the state of FIG.
7 are separated. Therefore, the negative pressure from the pressure introduction passage 50 is introduced into the second chamber 35 via the space 51, and no boosting action is performed.

On the other hand, when the brake pedal 12 is depressed in such a state, the input shaft 44 and thus the valve plunger 45 move forward (to the left in the drawing). During this movement, the vacuum valve 46 is first seated on the valve seat 47 and
And the pressure introduction passage 50 are cut off.
6, the valve seat 45a is separated. When the vacuum valve 46 and the valve seat 45a are separated from each other, the atmospheric pressure from the rear of the valve body 33 is introduced into the space 51, and the second chamber 35
Becomes atmospheric pressure. As a result, the diaphragm 32 is displaced forward together with the valve body 33, and as a result, the output shaft 4
3 moves forward and a boosting action is performed. The brake reaction from the master cylinder 8
Is transmitted to the valve plunger 45 and eventually to the brake pedal 12. When the depressing operation force of the brake pedal 12 is released, the state is returned to the state shown in FIG.

Although the parts described above are the same as those of the known vacuum booster, in this embodiment, the negative pressure of the first chamber 34 is introduced into the pressure introduction passage 50 for slip control. And a state in which atmospheric pressure is introduced. That is, the first chamber 34 and the pressure introduction passage 50 are connected via the pipe 37, and the pipe 37 is provided with an electromagnetic three-way switching valve 38 (see FIG. 1). The switching valve 38 communicates the pressure introduction passage 50 with the first chamber 34 during demagnetization, and introduces atmospheric pressure into the pressure introduction passage 50 during excitation. And this switching valve 3
When the pressure 8 is excited and the atmospheric pressure is introduced into the pressure introducing passage 50, the space 51 and thus the second chamber 35 become the atmospheric pressure even if the brake pedal 12 is not depressed. By performing the operation, the brake fluid pressure is generated in the master cylinder 8.

FIG. 3 schematically shows a control system of the slip control device. In the figure, reference numerals 61 to 64 denote wheel speed sensors for detecting the rotation speeds of the wheels 1FL to 1RR. Here, since the rotation speeds of the rear wheels 1RL, 1RR, which are driven wheels, are proportional to the vehicle speed (also referred to as vehicle speed or vehicle speed), wheel speed sensors 63, 64 for detecting the rotation speeds of the rear wheels 1RL, 1RR. Has also a function as a vehicle speed detecting means for detecting a vehicle speed.

An accelerator switch 65 is turned on when the accelerator pedal 10 is fully closed, and brake switches 66 and 67 are each operated when the brake pedal 12 is depressed. One switch is normally open and the other is normally closed.
68 is an accelerator opening sensor for detecting the accelerator opening, 6
Reference numeral 9 denotes a pump failure detecting means for detecting a failure of the vacuum pump 39 from a negative pressure generation state. The signals of the various sensors or switches 61 to 69 are transmitted to a control unit 7 configured using a microcomputer.
1 is input.

The control unit 71 includes a wheel speed sensor 6
Front wheels 1F as driving wheels based on signals from 1 to 64
Slip amount detecting means 72 for detecting the slip amount of L, 1FR, and various valves 15L of the brake control system so as to suppress the slip of the front wheels 1FL, 1FR based on the detection result by the slip amount detecting means 72 and the like. , 15R, 16
L, 16R, and 38, and a slip control means 74 for controlling the operation of a torque adjusting means 73 for adjusting the torque generated by the engine 2;
And a slip control restricting means 75 for restricting the slip control (specifically, brake traction control) by the slip control means 74 when the vacuum pump 39 fails.

The slip control (traction (TRC) control) by the slip control means 74 is a brake control (brake traction control) for controlling a braking force applied to the drive wheels 1FL and 1FR by switching various valves of a brake control system. And engine control (engine traction control) for adjusting the generated torque of the engine 2 by the torque adjusting means 73. Although not shown in detail in the drawing, the torque adjusting means 73 includes a sub-throttle valve provided in the intake passage 20 of the engine 2 together with the main throttle valve 17, and an actuator for adjusting the opening of the sub-throttle valve. The generated torque is adjusted by adjusting the opening of the sub-throttle valve. The torque adjusting means 73 is not limited to the one in the present embodiment. For example, the torque adjusting means 73 may adjust the generated torque by adjusting the intake air amount or by combining the number of fuel cut cylinders and the ignition timing. Good.

Next, the contents of the traction control will be described with reference to FIG.

In FIG. 4, since no significant slip has occurred in the drive wheels before the time t1, no engine control is performed, and therefore the sub-throttle valve is fully opened and the throttle opening Tn (main and The combined opening of the sub-throttle valve, which corresponds to the opening of the smaller throttle valve) is the main throttle opening TH · M corresponding to the accelerator depression amount.

At time t 1, the slip amount of the drive wheel becomes S
This is the time when a large slip, which is ET, occurs. In this state, the accelerator pedal 19 is depressed, and the traction control is started unless the depression is released or the brake pedal 12 is not depressed. And
At this time point t1, the throttle opening is reduced to the lower limit control value SM at once (feed forward control). Then, once the SM is set, the slip amount of the drive wheel is set to the SET.
The opening degree of the sub-throttle valve is feedback-controlled so that At this time, the throttle opening Tn becomes the subthrottle valve opening TH · S.

At the time t2, the slip amount of the drive wheel becomes SB
T, and at this time, the brake fluid pressure is supplied to the brakes 7FL and 7FR of the drive wheels,
Traction control by both engine control and brake control is started. The brake fluid pressure is feedback-controlled so that the slip amount of the drive wheel becomes SBT.

At time t 3, the slip amount of the drive wheel becomes SB
This is the time when it becomes less than T, whereby the brake fluid pressure gradually decreases, and eventually the brake fluid pressure becomes zero.
However, engine control is still continued.

The above-described traction control is conventionally known, and the feature of the present invention is that the slip control restricting means 75 restricts the brake control of the traction control when the vacuum pump 39 fails. The control for this restriction is performed according to the flowchart shown in FIG.

That is, after starting, first of all,
In step S1, it is determined based on a signal from the pump failure detecting means 69 whether or not the vacuum pump (VP) 39 has failed. If this determination is NO, the process returns as it is, while if the determination is YES, a determination is made as to whether or not traction control is being performed based on a signal from the traction control unit 74 in step S2. If the traction control is not being performed, that is, if NO, it is determined in step S3 whether a predetermined time has elapsed from the time when the vacuum pump 39 failed.

After a lapse of a predetermined time from the failure of the vacuum pump 39, the brake traction control by the slip control means 74 is stopped in step S4, and the process returns thereafter.

On the other hand, if the traction control in step S2 is YES, the traction control currently being performed is ensured in step S5, and after the control is completed, the process proceeds to step S4 to stop the brake traction control. I do.

Therefore, according to the traction control regulation control, when the vacuum pump 39 fails, the brake control of the traction control is stopped after a predetermined time has elapsed from the time when the failure occurs. The negative pressure is not consumed in the brake booster 11 due to the brake traction control. For this reason, even when the negative pressure is not supplied from the vacuum pump 39 to the first chamber 34 of the brake booster 11 and the intake negative pressure supplied from the intake passage 20 of the engine 2 is not low, the brake booster 11 operates normally. Since the time when the brake does not operate normally due to lack of negative pressure during braking can be delayed, the brake booster 11 can operate normally over several times of normal brake braking, and safety can be ensured. it can.

In addition, immediately after the failure of the vacuum pump 39, since the vacuum pressure is sufficiently accumulated in the vacuum pump 39 and the brake booster 11, etc., even if the brake traction control is performed during this time as in the above embodiment, Not only does not cause any trouble at the time of normal brake braking, but also the driving wheels (front wheels 1
Fl, 1FR) can be effectively suppressed.

Further, in the above embodiment, when a failure of the vacuum pump 39 occurs and is detected during the traction control, the subsequent brake traction control is restricted when the control is completed. It is possible to prevent the behavior of the vehicle from becoming unstable due to abrupt regulation, and to further improve safety.

[0040]

As described above, according to the vehicle slip control apparatus of the present invention, when the vacuum pump fails, the brake traction control is restricted and the negative pressure of the brake booster is secured without being consumed. It can be ensured that the brake booster operates normally at the time of brake braking, and safety can be improved.

[0041] Particularly, when the vacuum pump is fail during braking traction control, since the subsequent brake traction control at the time the control is finished is restricted, unstable behavior of the vehicle is due to a rapid regulation of the brake traction control Can be prevented, and safety can be further improved.

[Brief description of the drawings]

FIG. 1 is an overall configuration diagram of a vehicle slip control device according to an embodiment of the present invention.

FIG. 2 is a sectional view of a main part of a brake booster.

FIG. 3 is a block diagram of a control system of the slip control device.

FIG. 4 is a time chart of slip control.

FIG. 5 is a flowchart illustrating regulation control for slip control.

[Description of Signs] 1FL, 1RR Front wheel (drive wheel) 2 Engine 8 Master cylinder 11 Brake booster 18 Supercharger 39 Vacuum pump 69 Pump failure detection means 75 Slip control restriction means

──────────────────────────────────────────────────続 き Continued on the front page (58) Field surveyed (Int. Cl. ⁷ , DB name) B60T 8/58 B60T 8/88 B60T 17/00 B60K 41/20

Claims (1)

(57) [Claims] 1. A slip control device for a vehicle, wherein a master cylinder is driven by a brake booster to apply a braking force to the drive wheel when the drive wheel is in a slip state. A vacuum pump for generating pressure, a pump failure detecting means for detecting a failure of the vacuum pump, and a regulating means for regulating the application of a braking force to the drive wheel when the failure of the vacuum pump is detected by the detecting means. provided, the regulating means, application of braking force to the drive wheels row
Vacuum pump failure is detected during
When the brakes are released,
A vehicle slip control device provided so as to regulate application of force .