JP3266657B2 - Anti-lock brake device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a master cylinder for generating a hydraulic braking pressure in response to depression of the brake operation element, a brake cylinder for braking a wheel, a hydraulic pressure source for generating a control hydraulic pressure, the master cylinder and the brake An oil passage opening / closing valve provided in an oil passage between the cylinder and an anti-lock control valve capable of switching between a step-down state in which at least the brake cylinder is connected to a reservoir during anti-lock control and a step-up state in which the brake cylinder is connected to a hydraulic source during anti-lock control; And an anti-lock brake device comprising:

[0002]

2. Description of the Related Art An example of such an anti-lock brake device is disclosed in Japanese Utility Model Publication No. 4-23718.

[0003]

The above-described conventional anti-lock brake device selects the larger one of the brake oil pressure from the master cylinder and the control oil pressure from the oil pressure source and transmits the selected oil passage to the brake cylinder. A valve is provided to allow communication between the master cylinder and the brake cylinder during normal braking, and to block the communication during antilock control to connect the hydraulic pressure source to the brake cylinder. For this reason, during the transition from the low friction coefficient road surface (hereinafter referred to as low μ road) to the high friction coefficient road surface (hereinafter referred to as high μ road) during the antilock control shown in FIG. Output hydraulic pressure from master cylinder
Exceeds the control oil pressure and has a high select function.
Transmitted to the brake cylinder via the
Is that there is, brake feeling increased strokes blur <br/> Kipedaru is as indicated by this time (A ') there is a problem of decrease.

The present invention has been made in view of such circumstances, and has as its object to prevent an increase in the stroke of a brake pedal during antilock control.

[0005]

In order to achieve the above object, an antilock brake device according to the present invention comprises a master cylinder for generating a brake oil pressure in response to operation of a brake operator, and a brake cylinder for braking wheels. , Control oil pressure source and master cylinder output oil
Interposed in the first oil passage for transmitting pressure to the brake cylinder
It is, boosting the oil passage opening and closing valve for closing <br/> when the valve is opened by anti-lock control during normal braking, to communicate the at least buck state and a brake cylinder for communicating brake cylinder to the reservoir to the hydraulic pressure source during the anti-lock control Anti-lock control valve that can switch the state and oil passage opening and closing valve
Oil passage connected to the first oil passage to bypass the
Is in the check valve from the master cylinder to regulate the flow of hydraulic fluid to the brake cylinder, by releasing the control oil pressure to be transmitted from the anti-lock control valve when A Nchirokku control the brake cylinder to the reservoir,
And a constant pressure valve for regulating so as not higher than a predetermined value to the brake hydraulic pressure upper limit value of the control hydraulic pressure generated by the master cylinder, the pressure valve, co
Control oil pressure in the valve opening direction.
Second oil that communicates between hydraulic source and anti-lock control valve
That opens and closes between the passage and a third oil passage connected to the reservoir
And a valve spring that constantly biases the valve body in the closing direction.
Set the valve spring load to the output hydraulic pressure from the master cylinder.
And a set load changing means for increasing the load according to the increase .

[0006]

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

1 to 3 show a first embodiment of the present invention. FIG. 1 is a hydraulic circuit diagram of an antilock brake device,
2 is an enlarged view of a part of FIG. 1 showing the structure of the constant pressure valve, and FIG. 3 is a graph showing the operation of the antilock brake device according to the present embodiment.

As shown in FIG. 1, a tandem type master cylinder Mc for an automobile, which is connected to a brake pedal 1 and operates, is provided integrally with a reservoir 2 for storing hydraulic oil at an upper portion thereof and brakes left and right front wheels. Front output port 3 connected to a pair of brake cylinders Bc _FL and Bc _FR
And a pair of brake cylinders Bc for braking the left and right rear wheels.
_RL , Bc _RR .

The front wheel anti-lock control system provided between the front output port 3 and the front wheel brake cylinders Bc _FL and Bc _FR includes a rear output port 4 and the rear wheel brake cylinders Bc _RL and Bc _RR . Since it has substantially the same structure as the rear wheel antilock control system provided between
Hereinafter, the structure of the front wheel side antilock control system will be described as a representative, and the same description will be given to the rear wheel side antilock control system, and redundant description will be omitted.

[0010] The first oil passage L ₁ extending from the front output port 3 of the master cylinder Mc is bifurcated, the first oil passage L ₁
Left and right brake cylinders B via oil passage opening / closing valves 5 and 5 each comprising a solenoid valve capable of opening and closing the brake cylinder B
Connected to c _FL and Bc _FR . Each oil passage opening and closing valve 5,5
An oil path connected to the first oil passage L ₁ by bypassing the brake cylinder Bc _FL, master cylinder Mc from Bc _FR side
Check valves 6 and 6 that allow only the flow of hydraulic oil to the side are interposed .

A second oil passage L ₂ extending from the reservoir 2 of the master cylinder Mc is connected to a hydraulic pump 8 driven by a motor 7.
Is provided after the second oil passage L ₂ leading to the discharge side of the hydraulic pump 8 is branched into two, the respective bifurcated through the antilock control valves 9, 9 made of 3 position switchable solenoid valve First oil passage L branched to
Connected to ₁ . And wherein the second oil passage L ₂ leading to the suction side and the discharge side of the hydraulic pump 8, a pair of check valves 10, 10 for restricting the reverse flow of the hydraulic fluid is respectively provided in series. Also in the second oil passage L ₂ on the discharge side of the hydraulic pump 8, the accumulator 11 is provided.

The oil passage opening / closing valves 5, 5, anti-lock control valves 9, 9 and hydraulic pump 8 are connected to an electronic control unit (not shown). Is controlled based on the output of

A low-pressure third oil passage L ₃ connected to the reservoir 2 of the master cylinder Mc and a second hydraulic passage L ₃ downstream of the hydraulic pump 8.
An oil passage L _2, between the upstream first oil path of the oil passage opening and closing valve 5 and 5, a constant pressure valve 12 is disposed.

Next, referring to FIG.
The structure of will be described.

The constant pressure valve 12 includes a bottomed cylindrical housing 21, communicating with the opening of the housing 21 and a cap 23 for closing over the packing 22, the first oil passage L ₁ the cap 23 A first port P ₁ is formed at the bottom of the housing 21, a second port P ₂ connected to the second oil passage L ₂ is formed, and a third port P ₃ connected to a third oil passage is formed at a side wall of the housing 21. Is done.

A piston 24 is slidably fitted in the housing 21 via a seal member 25, and a leg 26 ₁ is slidably fitted in a guide hole 24 ₁ formed in the piston 24. The valve body 26 is housed in an oil chamber 27 formed on the bottom side of the housing 21. A valve spring 28 is contracted between the head 26 _{2 of the} valve body 26 and the piston 24, and the elastic force of the valve spring 28 causes the head 26
Valve head 26 ₃ formed ₂ closes the second port P _2.
Note that the leg portions 26 ₁ of the valve element 26, the grooves 26 ₄ for releasing hydraulic oil guide hole 24 ₁ of the piston 24 is formed.

When the control pressure acting on the second port P ₂ exceeds the set load of the valve spring 28, the valve 2
6 By moves rightwards against the valve spring 28, the second port P ₂ is communicated with the third port P _3. When the piston 24 is moved leftward in response to an increase of the master cylinder Mc of hydraulic braking pressure transmitted to the first port P _1, the valve spring 2
8 is compressed and its set load increases. Therefore
The piston 24 constitutes the set load changing means of the present invention.
You.

Next, the operation of the first embodiment of the present invention having the above configuration will be described. Since the functions of the front wheel side and the rear wheel side antilock control systems are substantially the same, the function of the front wheel side antilock control system will be described below as a representative.

At the time of normal braking without the possibility of the wheels being locked, the oil passage opening / closing valves 5, 5 are controlled by a command from the electronic control unit.
Is held at the right position shown, and the antilock control valves 9, 9 are held at the center position shown. Therefore,
The brake hydraulic pressure output from the front output port 3 of the master cylinder Mc by operating the brake pedal 1
From the oil passage L ₁ bifurcated through the oil passage opening and closing valve 5,5, left and right brake cylinders Bc _FL, it is transmitted to Bc _FR.

When it is detected that the front wheels have a tendency to lock, an oil passage opening / closing valve 5,
5 is switched to the left position, and the anti-lock control valves 9, 9 are switched to the left position. as a result,
The brake hydraulic pressure from the master cylinder Mc is blocked by the oil passage opening / closing valves 5 and 5, and the brake cylinder Bc _FL ,
Bc _FR is not transmitted to Bc _FR , and at the same time, the brake hydraulic pressure of the brake cylinders Bc _FL and Bc _FR is transferred from the first oil passage L ₁ to the third oil passage L ₃ connected to the reservoir 2 through the antilock control valves 9 and 9. Escaped. As a result, the braking forces of the brake cylinders Bc _FL and Bc _FR are weakened, and the locking of the front wheels is suppressed.

When the locking tendency of the front wheels is weakened by the above operation, the antilock control valves 9, 9 are switched to the center position. As a result, communication between the first oil passage L ₁ and the third oil passage L ₃ is prevented, the brake cylinder Bc _FL, brake hydraulic pressure of Bc _FR is maintained. When the locking tendency of the front wheels is further weakened, the antilock control valves 9, 9 are switched to the right position. As a result, transmission control pressure accumulated in the accumulator 11 by the hydraulic pump 8 from the second oil passage L ₂ brake cylinders Bc _FL through the antilock control valves 9, 9, the first oil passage L ₁ connecting to Bc _FR As a result, the braking force of the brake cylinders Bc _FL and Bc _FR is increased.

By controlling the anti-lock control valves 9 and 9 during the anti-lock control, the hydraulic pressure transmitted to the brake cylinders Bc _FL and Bc _FR is reduced or reduced in accordance with the tendency of the front wheels to lock. Holding and increasing the pressure prevent the front wheels from entering the locked state.

The motor 7 of the hydraulic pump 8 is driven at least during the antilock control, and the accumulator 11 is always kept in the pressure accumulation state. When the control pressure in the second oil passage L ₂ by the excess of hydraulic oil discharged from the hydraulic pump 8 is excessive, the pressure is released to the third oil passage L ₃ leading to the reservoir 2 via a constant pressure valve 12.

[0024] That is, as is clear from FIG. 2, when the control pressure in the second oil passage L ₂ becomes excessive, constant pressure valve 12
The valve body 26 moves to the right while compressing the valve spring 28 by the control pressure transmitted to the second port P ₂ of the second port P ₂ , so that the excess hydraulic oil supplied to the second oil passage L ₂ loses the second port P ₂ , the oil chamber 27, through the third port P ₃ and the third oil passage L ₃ flows back to the reservoir 2.

Now, during the antilock control, the antilock
The control valves 9, 9 are switched to the right position to
Linda Bc_FL, Bc_FRHydraulic pressure transmitted to is increased
Time, brake cylinder Bc_FL, Bc_FRSide pressure is master
When the pressure becomes higher than the pressure on the cylinder Mc side,The brake
Linda Bc _FL , Bc _FR Side pressure is the check valve 6,6
Is transmitted to the master cylinder Mc side throughMaster series
So-called kickback when pedal Mc1 is pushed back
Elephants may occur and impair brake feelingAh
You. However, according to the present invention, the kickback current
Elephant can be reduced by the action of the constant pressure valve 12.
You.

That is, as described above, the brake cylinder Bc
Second oil passage L ₂ for increasing the hydraulic pressure transmitted to _FL and Bc _FR
Is increased, the control pressure is released to the reservoir 2 by moving the valve body 26 of the constant pressure valve 12 rightward against the set load of the valve spring 28. At this time, as shown in FIG. 2, since the first port a first pressure oil passage L ₁ leading to the master cylinder Mc to P ₁ of the constant pressure valve 12 is acting, it is moved to the left the piston 24 is the pressure The set load of the valve spring 28 is increased. In other words, since the set load of the valve spring 28 increases with an increase in the pressure on the master cylinder Mc side,
The upper limit value of the control pressure determined by the set load of the valve spring 28 also increases as the pressure on the master cylinder Mc side increases. As a result, the difference between the upper limit value of the control pressure and the pressure on the master cylinder Mc side is regulated to a constant value determined by the characteristics of the valve spring 28, so that the pressure on the brake cylinders Bc _FL and Bc _FR side becomes
It is prevented that the pressure becomes higher than the pressure on the c side, thereby reducing the kickback phenomenon of the master cylinder Mc.

When the brake pedal 1 is depressed during antilock control, the brake cylinder Bc _FL ,
When the pressure on the Bc _FR side becomes lower than the pressure on the master cylinder Mc side, the check valves 6 and 6 that bypass the oil passage opening and closing valves 5 and 5 in the closed state are opened, and the brake cylinder is opened.
The oil on the Bc _FL and Bc _FR sides smoothly moves to the master cylinder Mc side.
Returned to

On the other hand, if the pressure on the master cylinder Mc becomes higher than the pressure on the brake cylinders Bc _FL and Bc _FR when the depression force of the brake pedal 1 is increased during the antilock control, the check valves 6 and 6 are activated. Close the valve , and this
Occasionally, the oil passage opening / closing valves 5 and 5 are in a shut-off state
Therefore, from the master cylinder Mc to the brake cylinder B
c _FL, the first oil passage L ₁ extending Bc _FR is closed, the brake pedal 1 is not pushed.

That is, as is apparent from FIG. 3, after the vehicle enters the anti-lock control state shown in FIG. 3B from the normal braking state shown in FIG. The stroke of the pedal 1 is kept constant, thereby preventing a decrease in brake feeling.

[0030] Incidentally, when the control pressure in the second oil passage L ₂ becomes impossible antilock control is reduced by failure of the hydraulic pump 8, the oil passage opening and closing valve 5,5 and anti-lock control valve 9 , 9 are fixed in the state shown in FIG. As a result, the brake oil pressure generated in the master cylinder Mc becomes the same as the brake cylinder Bc _FL , B
c The braking force is transmitted to the _FR to secure the braking force.

FIG. 4 shows a second embodiment of the present invention.
FIG. 3 is a sectional view of a constant pressure valve corresponding to FIG. 2.

The constant pressure valve 12 of this embodiment includes a return spring 29 contracted between the piston 24 and the cap 23 in addition to a valve spring 28 contracted between the piston 24 and the valve body 26. Prepare. Thus, the brake hydraulic pressure valve spring 28 which is transmitted from the master cylinder Mc to the first port P ₁
When the valve spring 28 moves leftward against the return spring 29, the set load of the valve spring 28 increases, so that the valve opening pressure of the valve body 26 determined by the set load of the valve spring 28, that is, the second port P
The difference between the upper limit value of the control pressure acting on ₂ and the pressure on the master cylinder Mc side is regulated to a constant value.

In this embodiment, since the return spring 29 of the piston 24 and the valve spring 28 of the valve body 26 are separated, the valve opening pressure of the valve body 26 can be easily set, and the degree of freedom of design can be improved. Can be increased.

Although the embodiments of the present invention have been described in detail, the present invention is not limited to the above embodiments, and various design changes can be made.

[0035]

As described above, according to the present invention, the master system
To transmit the output hydraulic pressure of the cylinder to the brake cylinder
In the first oil passage, the valve opens during normal braking and during antilock control.
An oil passage opening / closing valve to be closed is interposed, and an oil passage connected to the first oil passage so as to bypass the oil passage opening / closing valve.
That the check valve, since the master cylinder and regulates the flow of hydraulic fluid to the brake cylinder, during anti-lock control in which the oil passage opening and closing valve is closed, Masutashirin
To reliably prevent hydraulic pressure transmission from the damper to the brake cylinder side.
Te, regulate the depression of the brake pedal of the master cylinder, Ru can improve brake feeling.
In addition, if the brake pedal is released during this antilock control , the brake cylinder must pass through the above check valve.
Oil can be returned smoothly to the master cylinder side
From above, the closed state is maintained during the antilock control.
The hydraulic pressure of the brake cylinder can be reduced quickly even with the special provision of the oil passage opening / closing valve .

With the special installation of the check valve,
Increase brake hydraulic pressure with control hydraulic pressure during lock control
When trying to do so, the brake oil pressure
Although it may be transmitted to the star cylinder side,
From the antilock control valve during antilock control
Upper limit of control oil pressure transmitted to brake cylinder
The value is different from the brake oil pressure generated in the master cylinder.
Equipped with a constant pressure valve that regulates so that it does not become higher than the fixed value
Therefore, the kickback phenomenon that occurs in the master cylinder can be reduced.

In particular, the constant pressure valve is controlled by
It is configured to receive oil pressure in the valve opening direction,
Second oil passage and reservoir for communicating between antilock control valves
A valve body capable of opening and closing between a third oil passage connected to the valve and the valve;
A valve spring that constantly urges the body in the closing direction, and a valve spring
Load according to the increase in output oil pressure from the master cylinder
The load of the valve
It is necessary to attach an elastic seal part that has a large sliding resistance to itself.
It is no longer necessary, so the valve
A valve that receives output hydraulic pressure directly and has a constant set load of the valve spring
Compared with the structure, the response of the valve element can be improved effectively.
Wear.

[Brief description of the drawings]

FIG. 1 is a hydraulic circuit diagram of an anti-lock brake device.

FIG. 2 is an enlarged view of a part of FIG. 1 showing a structure of a constant pressure valve.

FIG. 3 is a graph showing the operation of the antilock brake device of the embodiment.

FIG. 4 is a view corresponding to FIG. 2 according to a second embodiment.

FIG. 5 is a graph showing the operation of a conventional antilock brake device.

[Explanation of symbols]

Reference Signs List 1 brake pedal (brake operator) 2 reservoir 5 oil passage opening / closing valve 6 check valve 8 hydraulic pump (hydraulic power source) 9 antilock control valve 11 accumulator (hydraulic power source) 12 constant pressure valve 24 piston (set load changing means) 26 valve body 28 valve springs Bc _FL , Bc _FR , Bc _RL , Bc _RR Brake cylinder L ₁ , L ₂ , L ₃ Oil passage Mc Master cylinder

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-62-166150 (JP, A) JP-A-52-70424 (JP, A) JP-A-57-65467 (JP, A) 62176 (JP, U) (58) Field surveyed (Int. Cl. ⁷ , DB name) B60T 8/48

Claims (1)

(57) [Claims] 1. A master cylinder for generating a hydraulic braking pressure in response to depression of the brake operation element (1) (Mc), a brake cylinder for braking a wheel (Bc _FL, Bc _FR, B
c _RL , Bc _RR ), the hydraulic pressure source (8, 11) that generates the control hydraulic pressure, and the output hydraulic pressure of the master cylinder (Mc)
(Bc _FL , Bc _FR , Bc _RL , Bc _RR )
It is interposed in the first oil passage (L _1), and an oil passage opening and closing valve is closed when the valve is opened and A <br/> Nchirokku control during normal braking (5), at least the brake cylinder during antilock control (B
c _FL , Bc _FR , Bc _RL , Bc _RR ) to communicate with the reservoir (2) and the brake cylinders (Bc _FL , B
c _FR, Bc _RL, and Bc _RR) to enable switching between the step-up state to communicate with the hydraulic pressure source (8, 11) for anti-lock control valve (9), the first oil to bypass the oil passage opening and closing valve (5) Road (L
₁ ) is installed in the oil passage connected to the master cylinder (M
c) to the brake cylinder (Bc _FL , Bc _FR , Bc _RL ,
Check valve (6) that regulates the flow of hydraulic oil to Bc _RR )
When, A Nchirokku control during the anti-lock control valve (9) from the brake cylinder _{(Bc FL, Bc FR, Bc} RL, B
c _RR ) The control oil pressure transmitted to the reservoir (2)
By releasing the, and a constant pressure valve (12) for regulating so as not higher than a predetermined value to the brake hydraulic pressure upper limit value of the control hydraulic pressure generated by the master cylinder (Mc), the constant pressure valve (12) is How to open control hydraulic pressure
Hydraulic sources (8, 11) and
Second oil passage communicating between antilock control valves (9)
(L ₂ ) and a third oil passage (L ₃ ) connected to the reservoir (2).
A valve body (26) that can open and close between the valve and this valve body (26)
A valve spring (28) that is constantly biased in the closing direction,
Set load of (28) from master cylinder (Mc)
Set load changing means to increase as output hydraulic pressure increases
(24) An anti-lock brake device characterized by having: