JP3101777B2 - 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 slip control device for a vehicle, and more particularly to a slip control device using a vacuum booster.

[0002]

2. Description of the Related Art When a vehicle is accelerating or the like, a driving wheel slips due to an excessive driving force, which may reduce the acceleration. Therefore, conventionally, when a slip ratio of a drive wheel to a road surface becomes equal to or more than a predetermined value, a slip control device that controls the driving force of the drive wheel so that the slip ratio (drive slip ratio) approaches a predetermined target drive slip ratio. Has been proposed. As a specific example of such a slip control device, there is known a device that performs driving force control by one or both of limiting an engine output (engine control) and applying a braking force to driving wheels (brake control). ing.

[0003] The above-described brake control has been conventionally performed, for example, in Japanese Patent Laid-Open No.
As disclosed in 3-281469, a brake pressure generating pump is provided between the brake pedal and the brake,
It has been performed by appropriately supplying the brake pressure generated by the brake pressure generating pump to the drive wheels.

[0004] Since the above-mentioned pump for generating brake pressure is large, Japanese Patent Publication No. 3-5344 discloses that a brake is controlled by using a negative pressure generated by a vacuum booster, and A slip control device that eliminates the pump has been proposed.

[0005]

In a brake control device using such a vacuum booster, a brake booster is operated by a brake pressure generating solenoid to generate a brake pressure, and the brake pressure is applied to the brake. A predetermined brake pressure is supplied to the drive wheels by adjusting the pressure by the pressure adjustment valve. In such a case, a brake for compensating the brake pressure reduced by the operation of the brake pressure adjustment valve is provided. It is necessary to provide a pressure supplement pump.
In such a brake control device, an initial check of whether the solenoid for generating brake pressure and the pump for replenishing brake pressure normally operate is performed in the brake control in order to appropriately perform the brake control. It needs to be done in advance.

The above-described initial check for the brake pressure generating solenoid is performed after the engine is started. However, since the negative pressure is accumulated in the vacuum booster by starting the engine, the timing of the initial check for the brake pressure generating solenoid is performed. Is too slow,
Performing the initial check causes a negative pressure loss of the vacuum booster, and also causes a problem that a brake system operates due to a brake pressure generated by the negative pressure and an overload acts on seals.

The present invention has been made in view of such circumstances, and in a vehicle slip control device using a vacuum booster, a negative pressure loss of the vacuum booster accompanying an initial check is reduced. It is another object of the present invention to provide a vehicle slip control device capable of improving the reliability of brake system seals.

[0008]

The slip control device for a vehicle according to the present invention achieves the above object by devising the order of the initial check.

In other words, a vacuum booster is provided between the brake pedal and the brake and amplifies the brake pressure generated by the depression operation of the brake pedal by using a negative pressure. A brake pressure generating solenoid for operating the vacuum booster to generate a brake pressure regardless of whether or not a brake pressure is generated, and a brake pressure generating solenoid provided between the vacuum booster and the brake to reduce and adjust the brake pressure. Controlling a brake pressure adjusting valve, a brake pressure replenishing pump that compensates for a brake pressure reduced by operation of the brake pressure adjusting valve, the brake pressure generating solenoid, the brake pressure adjusting valve, and the brake pressure replenishing pump; Control means for performing slip control by means of a vehicle. Stage, is characterized in that it is configured to perform before the initial check of the initial check of the brake pressure generating solenoid the brake 圧補 earmarking pump.

[0010]

As described above, the initial check of the solenoid for generating brake pressure is performed before the initial check of the pump for replenishing brake pressure, and therefore, the initial check for the solenoid for generating brake pressure is performed. The check can be performed at a timing when the negative pressure has not sufficiently accumulated in the vacuum booster.

Therefore, according to the present invention, in a slip control device for a vehicle using a vacuum booster, a negative pressure loss of the vacuum booster due to an initial check is reduced, and the reliability of brake system seals is improved. Can be achieved.

[0012]

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

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

As shown in FIG. 1, the vehicle provided with the slip control device is a front wheel drive vehicle in which front wheels 1FL and 1FR are drive wheels and rear wheels 1RL and 1RR are driven wheels. The engine 2 is mounted horizontally, and the torque generated by the engine 2 is the clutch 3, the transmission 4,
After being transmitted to the differential gear 5, it is transmitted to the left front wheel 1FL via the left drive shaft 6L and to the right front wheel 1FR via the right drive shaft 6R.

[0015] Brakes 7FL to 7R mounted on each wheel
R is a hydraulic disc brake, and a master cylinder 8 as a brake fluid pressure source has two discharge ports 8.
a and 8b. The brake pipe 13 extending from one discharge port 8a of the master cylinder 8 is branched into two on the way, and the branch pipe 13F is connected to the left front wheel brake 7FL (a wheel cylinder provided in the caliper of the brake). The branch pipe 13R is connected to the right rear wheel brake 7RR. The branch pipe 14 extending from the other discharge port 8b of the master cylinder 8 is also branched into two, the branch pipe 14F is connected to the right front wheel brake 7FR, and the branch pipe 14R is connected to the left rear wheel brake 7RL. .

Branch pipe 13 for front wheels, that is, for drive wheels
F and 14F are provided with electromagnetic hydraulic pressure regulating valves 15L and 15R.
(Brake pressure adjusting valve) is connected, and the branch pipe 1 for the rear wheel
Electromagnetic on-off valves 16L, 16R are connected to 3R, 14R. The hydraulic pressure regulating valves 15L, 15R supply the brake fluid pressure from the master cylinder 8 to the brakes 7FL, 7FR and supply the brake fluid pressure of the brakes 7FL, 7FR to the reservoir tanks 22L, 2R via the pipes 21L, 21R.
The mode for releasing to 2R is switched.
The brake fluid in the reservoir tank 22L is supplied to the pump 23L.
(Brake pressure supplement pump) is supplied to the pipe 13 through a pipe 25L to which a check valve 24L is connected. Similarly, the brake fluid in the reservoir tank 22R is supplied to the pump 2
3R (brake pressure supplement pump) allows check valve 24
R is supplied to the pipe 14 via the connected pipe 25R.

Each of the above-mentioned hydraulic pressure adjusting valves 15L, 15R and each of the on-off valves 16L, 16R are provided with a control unit 51.
(Control means).

The stepping force on the brake pedal 12 is
The power is transmitted to the master cylinder 8 via the brake booster 11 (vacuum booster). This booster 11 is basically the same as a known vacuum booster, but in a predetermined case, as will be described later,
It is configured to perform a boosting action even when the stepping operation 2 is not performed.

The booster 11 has a casing 31 fixed to the vehicle body and the master cylinder 8, and the casing 31 has a first chamber 34 and a second chamber 34 formed by a diaphragm 32 and a valve body 33 fixed thereto. 35. Negative pressure (for example, negative pressure of the intake pipe of the engine 2) is always supplied to the first chamber 34, and when the brake pedal is not depressed, the second chamber 35 becomes the first chamber 3
4, the operation of the booster 11 is stopped, and when the brake pedal 12 is depressed, atmospheric pressure is supplied to the second chamber 35, whereby the diaphragm 32 is displaced forward together with the valve body 33. Then, a boosting action is performed.

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. This valve body 33
The portion will be described with reference to FIG.

The valve body 33 has a power piston 41 fixed to the diaphragm 32. A reaction disk 42 and a base end of an output shaft 43 are accommodated in a recess 41a formed in the power piston 41. Mated. This output shaft 43 serves as an input shaft of the master cylinder 8. Further, a valve plunger 45 is attached to the distal end of the input shaft 44 connected to the brake pedal 12 within the valve body 33. Behind the valve plunger 45, a vacuum valve 46 is provided.

The power piston 41 has a pressure introducing passage 50.
Is formed, and the pressure introducing passage 50 is always communicated with a space X formed around the valve plunger 45. This space X is always in communication with the second chamber 35. A valve seat 47 is formed at an open end of the pressure introducing passage 50 toward the space X, on which the vacuum valve 46 is detached and seated. Further, the vacuum valve 46 is also separated from and seated on a valve seat 45a formed at the rear end of the valve plunger 45.

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 and 49 as shown in FIG. Are separated. Therefore, the negative pressure from the pressure introduction passage 50 is introduced into the second chamber 35 via the space X, and no boosting action is performed.

When the brake pedal 12 is depressed,
The valve plunger 45 moves forward (leftward in the figure) together with the input shaft 44. During this forward movement, the vacuum valve 46
First, the operator sits on the valve seat 47 to cut off the communication between the space X and the pressure introducing passage 50, and thereafter the valve seat 45 a is separated from the vacuum valve 46. When the vacuum valve 46 and the valve seat 45a are separated from each other, the atmospheric pressure from behind the valve body 33 is introduced into the space X, and the second chamber 35 becomes the atmospheric pressure. As a result, the diaphragm 32 is displaced forward together with the valve body 33, and as a result, the output shaft 43 moves forward and a boosting action is performed. The brake reaction force from master cylinder 8 is
It is transmitted to the valve plunger 45 and further to the brake pedal 12 via the reaction disk 42. When the depressing operation force of the brake pedal 12 is released, the state is returned to the state of FIG. 2 by the return spring 36 (see FIG. 1), and the vehicle is prepared for the next boosting action.

Although the above-described portion is the same as that of the known vacuum booster, in the present embodiment, the negative pressure of the second chamber 35 is supplied to the pressure introduction passage 50 for slip control described later. It is possible to switch between a state for introducing and a state for introducing atmospheric pressure. That is, the first
The chamber 34 and the pressure introduction passage 50 are connected via a pipe 37, and the pipe 37 has a three-way electromagnetic switching valve 38 controlled by a control unit 51 as shown in FIG.
(Brake pressure generating solenoid) is connected. The switching valve 38 connects the pressure introduction passage 50 to the first chamber 3 during demagnetization.
4 so that the atmospheric pressure is introduced into the pressure introducing passage 50 at the time of excitation. When the switching valve 38 is excited and the atmospheric pressure is introduced into the pressure introducing passage 50, the space X, and therefore the second chamber 35, becomes the atmospheric pressure even when the brake pedal 12 is not depressed, and as a result, the pressure becomes double. By performing a force action, a brake fluid pressure is generated in the master cylinder 8.

As shown in FIG. 1, signals from sensors or switches S _{1 to} S ₉ are input to the control unit 5. The sensors S _{1 to} S ₄
This is a wheel speed sensor that detects the rotation speed of each of the wheels 1FL to 1RR. Switch S ₅ is a accelerator switch the accelerator pedal 10 is turned on when the fully closed. Switches S ₆ and S ₇ are foot brake switches which are activated when the brake pedal 12 is depressed, and one switch is normally open and the other is normally closed. Switch S ₈ is a parking brake switch which is turned on when the parking brake (not shown) is actuated. Switch S ₉ is a manual switch for stopping the braking function of the hill holder mechanism (not shown) by a manual operation.

The control unit 51 also outputs a control signal to the torque adjusting means 9 for adjusting the engine output (torque generated by the engine 2). The torque adjusting means 9 adjusts the generated torque by, for example, adjusting the intake air amount or by combining the number of fuel cut cylinders and the ignition timing.

The control unit 51 performs ABS control (braking force control) during vehicle braking as slip control.
And TRC control (driving force control) during vehicle acceleration. ABS control is performed by the hydraulic pressure adjusting valve 15L, 1
The TRC control is performed by operation control on the three-way electromagnetic switching valve 38, the hydraulic pressure adjustment valves 15L and 15R (brake control), and operation control on the torque adjustment means 9 (engine control). ).

The TRC control by the control unit 51 is performed independently for each of the left and right rear wheels 3 and 4. For example, for the left rear wheel 3, it is performed as follows.

That is, first, the control unit 5
1, from a table set in advance the road surface friction coefficient μ (as estimated by the rear wheel acceleration A _R obtained therefrom and the average rear wheel speed V _R) as a parameter, the engine control start threshold S _EO and the engine control target value It reads the S _E and the brake control start threshold S _BO and the brake control target value S _B.

[0031] Here, it is shown in Table 1 when indicating road friction coefficient initiation threshold of μ and engine control S _EO and the target value S _E, the relation between the start threshold S _BO and the target value S _B of the brake control . In the present embodiment, the threshold S _EO engine control start is set to the same value as the engine control target value S _E, the brake control start threshold S _BO is set to the same value as the braking control target value S _B Have been.

[0032]

[Table 1]

In Table 1 above, each control start threshold value S _EO ,
S _BO and the respective control target values S _E and S _B are set as values corresponding to the slip ratio (drive slip ratio) of the left front wheel 1 with respect to the road surface.

The control unit 51 controls the front left wheel speed V
From _FL and the average rear wheel speed V _R, the following equation (1), and calculates the first driving slip ratio S _A1 with respect to the road surface of the left front wheel 1.

S _A1 = (V _FL -V _R ) / V _FL (1) The control unit 51 determines that the first drive slip ratio S _A1 is equal to the engine control start threshold S as shown in FIG.
At the time (t ₁ ) when _EO is exceeded, the engine control is started, and the torque adjusting means 9 is adjusted so that the engine control target value _SE is obtained.
Of the throttle opening adjustment actuator is feedback-controlled. Accordingly, the output torque of the engine 5 is to be controlled to converge to the engine control target value S _E.

If the left front wheel speed V _FL continues to increase without the slip condition being eliminated by this engine control, the first drive slip ratio S _A1 becomes equal to the brake control start threshold value S A.
At the time point (t ₂ ) exceeding _BO , the hydraulic pressure adjusting valve 15 of the left front wheel 1
The braking pressure is supplied to the L and three-way electromagnetic switching valve 38, and control using both engine control and brake control is performed. Incidentally, the brake pressure is feedback-controlled so that the first driving slip ratio S _A1 becomes the brake control target value S _B.

[0037] The first driving slip ratio S _A1 is at the time when lowered to the brake control target value S _B (t _3), the brake pressure is reduced brake control is stopped. The engine control is performed until a predetermined termination condition is satisfied.

The above control is similarly performed for the right front wheel 2. That is, the ECU 40 calculates the right front wheel speed V
Right front wheel speed it from the _FR by subtracting the average rear wheel speed V _R V _FR
The second drive slip ratio S _A2 for the right front wheel 2 is calculated. Then, when the second drive slip ratio S _A2 exceeds the engine control start threshold value S _EO set in the same manner as described above, the engine control is started, and the slip state is not canceled even by this engine control. When the right front wheel speed V _FR continues to increase and the second drive slip ratio S _A2 exceeds the brake control start threshold value S _BO in the same manner as described above, control using both engine control and brake control is performed. Then, the second drive slip ratio S _A2 is equal to the brake control target value S _B.
At this point, the brake control is stopped and the braking pressure is reduced.

The ABS control by the control unit 51 is performed independently for each wheel 1FL, 1FR, 1RL, 1RR. For example, for the left front wheel 1FL, from the left front wheel 1FL wheel speeds V _FL and estimated vehicle speed V _E (which will be described later), the following equation (2), the slip rate for the left front wheel 1FL road (first braking Slip ratio) S _ABS is calculated.

S _ABS1 = (V _E −V _FL ) / V _E (2) Then, when the first braking slip ratio S _ABS1 becomes _equal to or more than the ABS control threshold S _ABS , the first braking slip ratio S The braking force of the left front wheel 1FL is controlled so that _ABS1 approaches a predetermined target braking slip ratio.

As shown in FIG. 4, for example, and starts braking by depressing the brake pedal at the time point t ₁ now. Then, it is _assumed that the brake fluid pressure increases due to the depression of the pedal, the wheel speed of the left front wheel 1FL starts to decrease, and the first braking slip ratio S _ABS1 becomes _equal to or more than the ABS control threshold value S _ABS . Then, the control unit 51
, The left front wheel 1FL is determined that the tendency to lock, immediately starts the vacuum it is determined that the vacuum phase is t ₂ time.

[0042] As the estimated vehicle speed V _E, 4-wheel maximum wheel speed among the wheel speeds of, or, the vehicle speed in the vicinity of the start braking acceleration according to the road friction coefficient from (wheel speed) mu, for example - A vehicle speed reduced by 1.2 g (high μ) to −0.3 g (low μ) can be used.

Then, the brake fluid pressure is reduced, and at the time point t ₃ at which the rise of the slip ratio S _ABS stops, the holding phase is determined and the brake fluid pressure is held. _ABS1 increases again the brake fluid pressure is judged that the pressure increase phase at t ₄ when lowered to the threshold value S _ABS, the slip ratio in the same manner is reduced in pressure by the time t ₅ that exceeds the threshold S _ABS, slip held at t ₆ the increase rate _ABS1 is stopped, boosts at t ₇ the slip ratio S _ABS1 is lowered to the threshold, such vacuum holding, the target slip rate the slip rate while repeating pressure increasing cycle Is controlled.

Similarly, for the other wheels 1FR, 1RL, 1RR, the second, third, and fourth braking slip rates S
ABS control is performed when _ABS2 , S _ABS3 and S _ABS4 are _equal to or greater than the threshold value S _ABS .

To properly perform the above TRC control and ABS control, a switching valve 38 for generating brake fluid pressure and a pump 23 for compensating for a decrease in brake fluid pressure are provided.
It is important that L and 23R operate normally and a predetermined brake fluid pressure is secured.

Therefore, in this embodiment, the control unit 51 controls the switching valve 38 and the pump 23
An initial check is performed on L and 23R.

That is, as shown in the flowchart of FIG.
Starts (step T1), the vehicle speed V is zero (step T2), and the foot brake is off, that is, the brake pedal 12 is not depressed (step T3).
Under the condition that the solenoid for generating brake pressure (the switching valve 3
8) is operated to perform an initial check (step T4). It is determined whether this operation is normal (step T).
5) If normal, then the brake pressure replenishment pumps (pumps 23L and 23R) are operated to perform an initial check (step T6). If not, it is determined that the brake pressure generating solenoid is abnormal. (Step T7), and a warning lamp (No. 1) for notifying the abnormality is turned on (step T8).
Move to step T6. As a result of the initial check in step T6, it is determined whether or not the operation of the brake pressure replenishing pump is normal (step T9). If normal, the process returns to step T1. A failure determination is made that there is an abnormality in the refill pump (step T10), and a warning lamp (No. 2) for notifying the abnormality is turned on (step T1).
1).

As described in detail above, in the present embodiment, the initial check of the brake pressure generating solenoid is performed before the initial check of the brake pressure replenishing pump. Can be performed at a timing when the negative pressure is not sufficiently accumulated in the brake booster 11 yet.

Therefore, according to the present embodiment, in the vehicle slip control device using the brake booster 11, the negative pressure loss of the brake booster 11 due to the initial check is reduced, and the seals of the brake system (for example, the master cylinder 8) , Etc.) can be improved.

In this embodiment, the warning judgment of the brake pressure generating solenoid and the failure judgment of the brake pressure replenishing pump are respectively performed by the warning lamps (N
o. 1) and the warning lamp (No. 2) are lit and displayed independently, so that appropriate measures can be taken for each failure determination. For example, when only the warning lamp (No. 1) is turned on, T
It is possible to prohibit only the RC control and perform a switch operation or the like for continuing the ABS control.

[Brief description of the drawings]

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

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

FIG. 3 is a time chart showing an example of TRC control in the embodiment.

FIG. 4 is a time chart showing an example of ABS control in the embodiment.

FIG. 5 is a flowchart showing an operation in the embodiment.

[Description of Signs] 1FL, 1FR Front wheel (drive wheel) 1RL, 1RR Rear wheel (driven wheel) 2 Engine 7FL, 7FR, 7RL, 7RR Brake 8 Master cylinder 9 Torque adjusting means 11 Brake booster (vacuum booster) 12 Brake Pedal 15L, 15R Hydraulic pressure control valve (brake pressure control valve) 16L, 16R Open / close valve 23L, 23R Pump (brake pressure supplement pump) 38 Three-way electromagnetic switching valve (brake pressure generation solenoid) 51 Control unit (control means) S ₁ to S ₄ wheel speed sensor S ₅ accelerator switch S _6, S ₇ foot brake switch S ₈ parking brake switch S ₉ manual switch

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Keizumi Masu 3-1 Shinchi, Fuchu-cho, Aki-gun, Hiroshima Naru Deck Co., Ltd. (72) Koichi Hosoya 3-1 Shinchi, Fuchu-cho, Aki-gun, Hiroshima Naru JP-A-3-54057 (JP, A) JP-A-1-254460 (JP, A) JP-A-1-119461 (JP, A) JP-A-3-281469 (JP) JP-A-51-149472 (JP, A) JP-A-2-1933753 (JP, A) JP-B-3-5344 (JP, B2) (58) Fields investigated (Int. Cl. ⁷ , DB Name) B60T 8/88 B60T 8/58 B60T 13/52

Claims (2)

(57) [Claims] A vacuum booster provided between a brake pedal and a brake for amplifying a brake pressure generated by a depression operation of the brake pedal by using a negative pressure; A brake pressure generating solenoid for operating the vacuum booster to generate a brake pressure regardless of whether or not a brake pressure is generated, and a brake pressure generating solenoid provided between the vacuum booster and the brake to reduce and adjust the brake pressure. Controlling a brake pressure adjusting valve, a brake pressure replenishing pump that compensates for a brake pressure reduced by the operation of the brake pressure adjusting valve, the brake pressure generating solenoid, the brake pressure adjusting valve, and the brake pressure replenishing pump; Control means for performing a slip control by a vehicle, wherein the control means comprises: Serial slip control system for a vehicle, characterized by being configured to perform before the initial check of the the initial check of the brake pressure generating solenoid brake 圧補 earmarking pump. 2. The slip control of a vehicle according to claim 1, wherein the initial check of the solenoid for generating brake pressure is performed when three conditions of engine start, vehicle speed zero, and foot brake off are met. apparatus.