JPH0620870B2 - Vehicle braking hydraulic control device - Google Patents

Description

Detailed Description of the Invention A. Object of the Invention (1) Field of Industrial Application The present invention aims to reduce the pressure of the master cylinder output and guide it to the rear wheel brakes, and to stop the hydraulic pressure reducing action on the rear wheel brakes when the hydraulic pressure on the front wheel brake side fails. The present invention relates to a braking hydraulic pressure control device for a vehicle in which a housing is provided midway in an oil passage that connects a master cylinder to front wheel brakes and rear wheel brakes independently of each other.

(2) Conventional Technology Conventionally, such a device is disclosed in, for example, Japanese Patent Publication No. 51-48225
It is known from Japanese Patent Publication No.

(3) Problems to be Solved by the Invention However, in the above-mentioned conventional one, opening and closing the proportional pressure reducing valve provided in the housing to reduce the braking hydraulic pressure on the rear wheel brake side changes the rear wheel braking hydraulic pressure. In addition to the output hydraulic pressure on the rear wheel brake side,
Since it is a structure that also receives the output hydraulic pressure on the front wheel brake side,
The output hydraulic pressure on the front wheel brake side has a considerable influence on the pressure reducing action on the rear wheel brake side, and the braking hydraulic pressures on the rear wheel brake and the front wheel brake influence each other.

The present invention has been made in view of the above circumstances, and the braking hydraulic pressure of a vehicle is such that the pressure reducing characteristic of the braking hydraulic pressure on the rear wheel braking side is obtained without being affected by the braking hydraulic pressure on the front wheel braking side during normal operation. An object is to provide a control device.

B. Configuration of the Invention (1) Means for Solving the Problems In order to achieve the above object, the present invention is directed to a cylinder-shaped pressure receiving piston having a bottom and being slidably fitted in a cylinder hole of a housing. An output hydraulic chamber communicating with the rear wheel brake is defined between the outer surface of the closed end and the one end wall of the housing, and an input hydraulic chamber communicating with the master cylinder is formed in the pressure receiving piston with an inner surface of the closed end of the pressure receiving piston. A valve piston formed therebetween is slidably fitted, and a communication hole that connects the input hydraulic chamber and the output hydraulic chamber is coaxially formed at the closed end of the pressure receiving piston, and a valve body that controls the opening and closing of the communication hole. But,
A valve spring that is capable of relative movement in the axial direction in a limited range is connected to a valve piston in the input hydraulic chamber, and a valve spring that biases the valve body in a valve closing direction is interposed between the valve body and the valve piston.
A cylindrical receiving member, which is inserted into the cylinder hole so as to face the opening end of the pressure receiving piston, is elastically held in a contact position with the intermediate step portion of the cylinder hole, and the pressure receiving piston contracts the output hydraulic chamber. A spring that elastically urges in the direction to separate the pressure receiving piston and the receiving member from each other by a predetermined distance in a normal state is contracted between the receiving member and the pressure receiving piston, and moves toward the side away from the input hydraulic chamber of the valve piston. A regulating piston, one end of which engages with the valve piston to regulate the sliding limit, is slidably fitted in the cylinder hole, and the stopper part that regulates the sliding limit of this regulating piston to the valve piston side is the receiving member. The regulating piston is spring-biased in the engagement position with the stopper portion, and a regulating hydraulic chamber communicating with the master cylinder and the front wheel brake is defined between the other end of the regulating piston and the other end wall of the housing. Suko The features.

(2) Operation According to the above configuration, when the brake hydraulic system for both the front and rear wheels is operating normally, the regulating piston whose sliding on the valve piston side is regulated by the receiving member is The piston can be mounted in place. When the master cylinder output hydraulic pressure exceeds a certain value in this state, the pressure receiving piston moves toward the closing side due to the difference between the pressure receiving area of the pressure receiving piston facing the input hydraulic chamber and the pressure receiving area of the pressure receiving piston facing the output hydraulic chamber. By repeating the movement of the pressure receiving piston to the open side due to the increase of the hydraulic pressure in the input hydraulic chamber, the output hydraulic pressure of the master cylinder is reduced and transmitted to the rear wheel brakes. In this case, even if the braking hydraulic pressure on the front wheel brake side acts on the regulating piston, the sliding of the regulating piston to the valve piston side is reliably regulated by the receiving member as described above, and the braking hydraulic pressure on the front wheel braking side is regulated. Does not affect the reciprocating movement of the pressure receiving piston or the movement of the valve body connected to the valve piston, so that the pressure reducing characteristic of the braking hydraulic pressure on the rear wheel braking side is determined without being affected by the braking hydraulic pressure on the front wheel braking side. .

Also, especially when there is a hydraulic pressure failure on the front wheel brake side,
The valve piston presses the restriction piston to move, and the communication hole is held in the open state, so that the output hydraulic pressure of the master cylinder is supplied to the rear wheel brake without being reduced.

(3) Embodiment An embodiment of the present invention will be described below with reference to the drawings. First, referring to FIG. 1, a front wheel brake Bf of an automobile is shown.
An oil passage 1 is connected to l and Bfr, and an oil passage 2 is connected to the rear wheel brakes Brl and Brr. On the other hand, a pair of oil passages 3 and 4 are connected to the tandem type master cylinder M independently of each other, and the oil passages 1, 3; 2 and 4 are connected via the braking hydraulic control device 5 according to the present invention. It

In FIG. 2, the housing 6 of the braking hydraulic control device 5 is shown.
Is constructed by connecting the housing halves 6a, 6b, which are joined to each other via the seal member 7, to each other with bolts 8 and nuts 9. One housing half 6
A cylinder hole 10 formed by coaxially connecting a large-diameter portion 10a and a bottomed small-diameter portion 10b from the side of the other housing half 6b is formed in a, and the other housing half 6b is formed.
The large diameter portion 1 in order from the one housing half 6a side.
A cylinder hole 11 is formed by coaxially connecting 1a and a small diameter portion 11b having a bottom. Moreover, both cylinder holes 10,
Reference numeral 11 indicates a cylinder hole C of the housing 6 which is coaxial when the two housing halves 6a and 6b are joined, and the large diameter portions 10a and 11a are formed to have the same inner diameter. The small-diameter portion 10b has a larger diameter than the other small-diameter portion 11b.

A pressure receiving piston 13 that defines an output hydraulic chamber 12 is slidably fitted to the small diameter portion 10b of the cylinder hole 10 of one of the housing half bodies 6a between the closed end of the small diameter portion 10b. The body 6a is provided with an outlet hole 14 for communicating the output hydraulic chamber 12 with the oil passage 2. The pressure receiving piston 13 is formed in a bottomed cylindrical shape with its closed end facing the closed end of the small diameter portion 10b.
A valve piston 16 which forms an input hydraulic chamber 15 therebetween is slidably fitted in the valve 3. A cup seal 17 is fitted on the outer surface of the valve piston 16, and the cup seal 17 slidably contacts the inner surface of the pressure receiving piston 13.

Further, an annular groove 18 is provided on the outer surface of the intermediate portion of the pressure receiving piston 13, and the outer surface of the pressure receiving piston 13 which is closer to the output hydraulic chamber 12 than the annular groove 18 is in sliding contact with the inner surface of the small diameter portion 10b of the cylinder hole 10. The ring 19 is fitted and the O
A cup seal 20 which is slidably contacted with the inner surface of the small diameter portion 10b is fitted to the end of the annular groove 18 on the side opposite to the ring 19. As a result, both axial ends of the annular groove 18 are O-rings 19.
And it will be sealed with the cup seal 20. Moreover, the pressure receiving piston 13 is provided with an oil hole 21 communicating with the input hydraulic chamber 15 and opening to the annular groove 18, and the housing half 6a is provided with the oil passage 4 regardless of sliding of the pressure receiving piston 13. An inlet hole 22 that allows communication with 18 is formed. Therefore, the oil passage 4 always communicates with the input hydraulic chamber 15.

The closed end of the pressure receiving piston 13 is provided with a communication hole 23 coaxially with the cylinder hole 10 to connect the input hydraulic chamber 15 and the output hydraulic chamber 12, and the pressure receiving piston 13 contacts the closed end of the cylinder hole 10. Even in the contact state, a plurality of communication passages 24 extending in the radial direction are bored so that the communication hole 23 communicates with the output hydraulic chamber 12. On the other hand, in the input hydraulic chamber 15,
A valve body 25 that can close the communication hole 23 is housed, and a valve opening rod 26 that is inserted into the communication hole 23 is integrally provided in the valve body 25. As shown in FIG. 2, the length of the valve opening rod 26 is such that the tip of the valve opening rod 26 contacts the closed end of the cylinder hole 10 when the pressure receiving piston 13 is in contact with the closed end of the cylinder hole 10. It is set so that the valve body 25 can be held in the valve opening position when contacted. A connector 27 is attached to the valve body 25, and the valve piston 16 and the connector 27 are attached.
And are connected so as to allow relative movement in the axial direction within a limited range. That is, the valve piston 16 is integrally provided with a connecting rod 28 that projects into the connector 27, and an engaging flange 29 that is engageable with the inner end of the connector 27 is provided at the tip of the connecting rod 28. A valve spring 41 for urging the valve body 25 in the valve closing direction is contracted between the valve body 25 and the valve piston 16.

The receiving member 30 supported by the step portion 6s between the small diameter portion 11b and the large diameter portion 11a in the cylinder hole 11 of the other housing half body 6b is inserted. This receiving member 30
Is a cylindrical portion 30a facing the open end of the pressure receiving piston 13.
And a brim portion 30b that extends radially outward from the end of the cylindrical portion 30a so as to come into contact with the stepped portion 6s. Moreover, the coil-shaped spring 32 is contracted between the support ring 31 engaged with the outer surface of the pressure receiving piston 13 at the portion corresponding to the large diameter portion 10a of the cylinder hole 10 and the flange portion 30b of the receiving member 30. Due to the spring force of the spring 32, the pressure receiving piston 13 is spring-biased in a direction to contract the output hydraulic chamber 12, and the receiving member 30 is pressed against the housing half 6b.

Small diameter portion 1 of cylinder hole 11 in housing half 6b
A restriction piston 34 is slidably fitted to the 1b so as to define a restriction hydraulic chamber 33 between the closed end and a closed end, and a cup seal 35 that slidably contacts the inner surface of the small diameter portion 11b on the outer surface of the restriction piston 34. Is fitted. Further, a balance spring 36 is contracted between the closed end of the small diameter portion 11b and the restriction piston 34 in the restriction hydraulic chamber 33, and the restriction piston 34 functions as a stopper portion of the receiving member 30 by the spring force of the balance spring 36. It is urged in a direction of coming into contact with the opening end edge portion 30s on the side of the regulation hydraulic chamber 33. Moreover, the pressure receiving area A1 of the restriction piston 34 is set to be equal to or larger than the pressure receiving area A2 of the valve piston 16 (A1 ≧ A2). A restriction rod 37 that is inserted into the receiving member 30 is provided coaxially on the restriction piston 34, and the tip of the restriction rod 37 abuts the valve piston 16.

The housing half 6b has an inlet hole 38 for communicating the restriction hydraulic chamber 33 with the oil passage 3 and the restriction hydraulic chamber 33 with the oil passage 1.
And an outlet hole 39 for communicating with the.

Here, in the state of FIG. 2, the moving distance of the pressure receiving piston 13 from the valve opening position to the valve closing position of the valve body 25 is 11, the distance until the valve piston 16 is engaged with the connector 27 is 12, and the regulating piston 34. Let l3 be the distance to contact the closed end of the cylinder hole 11 and l4 be the distance to which the pressure receiving piston 13 contacts the receiving member 30.
There is the following relationship between 2, 13, and 14.

l1 + l3> l2 + l4 (1) Next, the operation of this embodiment will be described with reference to FIG. 3 as well. When the master cylinder M is not operating, the regulating piston 34 receives the restricting piston 34 by the balance spring 36.
The pressure receiving piston 13 is in contact with the closed end of the cylinder hole 10 by the spring 32, and the valve opening rod 26 of the valve body 25 is in contact with the closed end of the cylinder hole 10 by the valve spring 41. Therefore, the communication hole 23 is open.
When the master cylinder M is operated in this state, the braking hydraulic pressure output to one oil passage 3 is supplied to the front wheel brakes Bfl and Bfr via the regulation hydraulic chamber 33 and the oil passage 1, respectively, and to the other oil passage 4. The output braking hydraulic pressure is supplied to the rear wheel brakes Brl and Brr via the input hydraulic chamber 15, the communication hole 23, the output hydraulic chamber 12 and the oil passage 2.

At this time, the hydraulic pressure introduced from the master cylinder M to the input hydraulic chamber 15 is Pm, and the output hydraulic chamber 1 of the pressure receiving piston 13
When the pressure receiving area A3 facing 2 is set and the load of the spring 32 is set to W1, the following equation is established.

Pm · (A3-A2) <W1 ... (2) Further, the hydraulic pressure Pw of the output hydraulic chamber 12 and the hydraulic pressure Pm are equal (Pm = Pw).

When the hydraulic pressure Pm from the master cylinder M rises and reaches a certain value, the pressure receiving piston 13 overcomes the spring force of the spring 32 and starts rightward movement, and the communication hole 23 is closed by the valve body 25, and the input hydraulic chamber 15 and the output hydraulic chamber 12 are shut off. The oil pressure Pm at the time when the pressure receiving piston 13 starts to move is such that the O ring 19 and the cup seal 17,
It is expressed by the following equation when the sliding resistance of 20 is W2.

Further, the hydraulic pressure Pm (= Pc) of the input hydraulic chamber 15 when the communication hole 23 is closed is expressed by the following equation when the spring constant of the spring 32 is K.

When the hydraulic pressure Pm from the master cylinder M further rises,
The pressure receiving piston 13 moves to the left and the valve body 25 opens the communication hole 23 to increase the hydraulic pressure in the output hydraulic chamber 12. When this pressure reaches a certain value, the pressure receiving piston 13 moves to the right again to close the communication hole 23 and stop the pressure increase. By repeating such an action, the hydraulic pressure of the output hydraulic chamber 12, that is, the braking hydraulic pressure of the rear wheel brakes Brl, Brr gradually increases.

The hydraulic pressure Pw of the output hydraulic chamber 12 at the time of this pressure reducing action is represented by the following equation when the cross-sectional area of the communication hole 23 is A4.

Therefore, the pressure reduction ratio tan θ is expressed by the following equation (6).

From the equation (6), the pressure reduction ratio tan θ is calculated as the area A2, A3,
It turns out that it is determined by the relationship of A4. However, in reality, the resistance of each seal portion has a great influence on the stability of the characteristics during depressurization. To reduce this effect, the area A
2 and A3 may be increased to reduce the influence of the resistance of the seal portion as much as possible, so that stable depressurization characteristics can always be obtained.

When the output hydraulic pressure Pm of the master cylinder M drops,
Pressure receiving area A3 facing the output hydraulic chamber 12 of the pressure receiving piston 13
The pressure-receiving piston 13 moves to the right due to the relationship between the pressure-receiving area A2 facing the input hydraulic chamber 15 and expands the volume of the output hydraulic chamber 12 to reduce the outlet pressure Pw. Step-down slope ta at this time
nθ 'is expressed by the following equation.

tan θ ′ = A2 / A3 (7) Here, by decreasing the difference between tan θ and tan θ ′, it is possible to bring the boosting characteristic and the bucking characteristic closer to each other. Characteristics when boosting voltage (7)
Comparing with the characteristics at the time of step-down shown by the formula, the communication hole 23
The cross-sectional area A4 is different between tan θ and tan θ ′. Therefore, by increasing the pressure receiving areas A2 and A3 and reducing the cross-sectional area A4 of the communication hole 23 as much as possible, it is possible to bring the characteristics at the time of boosting and the characteristics at the time of reducing pressure close to each other to obtain a good hysteresis.

When the hydraulic pressure Pm from the master cylinder M further drops,
Due to the spring force of the spring 32, the pressure receiving piston 13 returns to the non-actuated position, and the communication hole 23 is opened.
Oil pressure Pw of the input oil pressure chamber 15 drops to the same pressure as the oil pressure Pm of the input oil pressure chamber 15.

Next, explaining the operation when a hydraulic pressure failure occurs,
First, when the hydraulic pressure failure occurs before the boosting operation of the master cylinder M in the system on the front wheel brakes Bfl and Bfr side, the master cylinder M is boosted because the hydraulic pressure is not acting on the restriction hydraulic chamber 33. Oil pressure Pm in the input oil pressure chamber 15
When the pressure is applied, the pressure receiving piston 13 remains in contact with the closed end of the cylinder hole 10 by the spring force of the spring 32, while the valve piston 16 overcomes the spring force of the balance spring 36 and presses the regulating piston 34. While moving to the right by a distance l3. At this time, the communication hole 23 remains open,
The hydraulic pressure Pw of the output hydraulic chamber 12 becomes the hydraulic pressure Pm and is increased. When the hydraulic pressure Pm reaches the hydraulic pressure Pc, the pressure receiving piston 13 moves rightward by the distance l4 against the spring force of the spring 32, but the valve piston 16 has already moved rightward by the distance l3 as described above. The communication hole 23 remains open, and therefore the hydraulic pressure Pw of the output hydraulic chamber 12 becomes the same as the hydraulic pressure Pm of the input hydraulic chamber 15 as shown by the broken line in FIG.

When the hydraulic pressure Pm from the master cylinder M is lowered, the pressure receiving piston 13 moves left by the spring force of the spring 32, and the valve piston 16 moves left by the spring force of the balance spring 36 to return to the non-actuated position of FIG. .

Further, when the hydraulic pressure failure occurs before the boosting operation of the master cylinder M in the system on the rear wheel brakes Brl, Brr side, the restriction piston 3 is increased in accordance with the increase in the hydraulic pressure in the restriction hydraulic chamber 33.
4 moves to the left while pressing the valve piston 16, and the receiving member 3
It stops when 0 is in contact with the pressure receiving piston 13. At this time, the oil passages 3 and 1 are in communication with each other via the restriction hydraulic chamber 33, and the braking hydraulic pressure on the front wheel brakes Bfl and Bfr side is secured.

The front wheel brake Bf during the depressurization operation of the braking hydraulic control device 5
When a hydraulic pressure failure occurs on the l, Bfr side, after the valve piston 16 and the restriction piston 34 move right by a distance l3, the pressure receiving piston 13 moves right by a distance l4 and stops.
Due to the dimensional relationship of the equation (1), the communication hole 23 is opened and the hydraulic pressure Pw of the output hydraulic chamber 12 becomes the same as the hydraulic pressure Pm of the input hydraulic chamber 15 as shown by the broken line in FIG.

Further, while the braking hydraulic control device 5 is in the pressure reducing operation, the rear wheel brake B
When a hydraulic pressure failure occurs on the rl and Brr sides, the pressure receiving piston 13 is moved to the non-operating position by the spring force of the spring 32, the communication hole 23 is opened, and the hydraulic pressure Pw of the output hydraulic chamber 12 and the input hydraulic pressure. The hydraulic pressure Pm of the chamber 15 is both 0 kg / cm ² . At this time, the restriction piston 34 moves left by the distance l4, and the braking hydraulic pressure on the front wheel brake Bfl, Bfr side is secured.

In such a braking hydraulic control device 5, the regulation hydraulic chamber 33 communicating with the oil passages 1 and 3 on the front wheel brakes Bfl and Bfr side.
The restriction piston 34 that receives the hydraulic pressure of the above only abuts the receiving member 30 to support the valve piston 16 during normal operation, and does not push and move the valve piston 16, so that the rear wheel brakes Brl and Brr side It does not affect the pressure reducing operation of the braking oil pressure, and therefore the pressure reducing characteristic of the braking oil pressure can be determined only by the braking oil pressure on the side of the rear wheel brakes Brl, Brr.

C. EFFECTS OF THE INVENTION As described above, according to the present invention, when both the front and rear wheels of the brake hydraulic system are operating normally, the regulation piston is restricted from sliding toward the valve piston by the receiving member. If the output oil pressure of the master cylinder exceeds a certain value in this state, the pressure receiving area of the pressure receiving piston facing the input oil pressure chamber and the pressure receiving area of the pressure receiving piston facing the output oil pressure chamber can be It is possible to reduce the output hydraulic pressure of the master cylinder and supply it to the rear wheel brakes by repeating the movement of the pressure-receiving piston to the closing side due to the difference in it can. In this case, even if the braking hydraulic pressure on the front wheel brake side acts on the regulating piston, the sliding of the regulating piston to the valve piston side is reliably regulated by the receiving member as described above, and the braking hydraulic pressure on the front wheel braking side is regulated. Does not affect the reciprocating movement of the pressure receiving piston or the movement of the valve element connected to the valve piston, so it is possible to determine the pressure reduction characteristics of the rear wheel brake side without being affected by the front wheel brake side brake oil pressure. Therefore, the response to the braking hydraulic pressure on the rear wheel brake side is excellent and a highly accurate pressure reducing action can be obtained.

Also, especially when there is a hydraulic pressure failure on the front wheel brake side,
The valve piston pushes the restriction piston to move it, which keeps the communication hole open, so the output hydraulic pressure of the master cylinder can be supplied to the rear wheel brake without being reduced, and therefore the rear wheel brake. Can be used effectively for braking.

[Brief description of drawings]

The drawings show one embodiment of the present invention. FIG. 1 is an overall hydraulic system diagram, FIG. 2 is a longitudinal sectional view of a braking hydraulic control device,
FIG. 3 is a pressure reduction characteristic diagram. 1 to 4 ... Oil passage, 5 ... Braking hydraulic control device, 6 ... Housing, 6s ... Step, 12 ... Output hydraulic chamber, 13 ...
Pressure receiving piston, 15 ... Input hydraulic chamber, 16 ... Valve piston, 23 ... Communication hole, 25 ... Valve element, 30 ... Receiving member, 30s ... Opening edge as stopper, C ...
Cylinder hole, 33 ... Regulator hydraulic chamber, 34 ... Regulator piston, 41 ... Valve spring, Bfl, Bfr ... Front wheel brake, Brl, Brr ... Rear wheel brake, M ... Master cylinder

Claims (1)

[Claims] 1. An output hydraulic pressure of a master cylinder (M) is reduced and guided to a rear wheel brake (Brl, Brr), and when the hydraulic pressure on the front wheel brake (Bfl, Bfr) side fails, it is applied to a rear wheel brake (Brl, Brr). The master cylinder (M) and front wheel brakes (Bfl, B)
fr) and the rear wheel brakes (Brl, Brr), the braking hydraulic pressure control device for a vehicle in which a housing (6) is provided in the middle of an oil passage (1 to 4) that connects the brakes independently of each other.
A bottomed cylindrical pressure receiving piston (13) is slidably fitted in a cylinder hole (C) of the housing (6), and an outer surface of a closed end of the pressure receiving piston (13) and one end of the housing (6). Between the wall and the rear wheel brake (Brl, Br
The output hydraulic chamber (12) communicating with r) is defined, and the input hydraulic chamber (15) communicating with the master cylinder (M) is formed in the pressure receiving piston (13) between the closed end inner surface of the pressure receiving piston (13). The valve piston (16) formed in the above is slidably fitted, and the closed end of the pressure receiving piston (13) connects the input hydraulic chamber (15) and the output hydraulic chamber (12) with a communication hole (2
3) is coaxially bored, and the valve body (25) that controls the opening and closing of the communication hole (23) enables relative movement in the axial direction in a limited range, and the valve piston (15) in the input hydraulic chamber (15). 16)
Connected to the valve body (25) and the valve piston (16)
In between, a valve spring (4) for urging the valve body (25) in the valve closing direction is provided.
1) is interposed and a cylindrical receiving member (30) is inserted into the cylinder hole (C) so as to face the opening end of the pressure receiving piston (13), and an intermediate step portion (6s) of the cylinder hole (C) is provided. ) Is elastically held in a contact position with the pressure receiving piston (13) and the pressure receiving piston (13) is elastically urged in a direction of contracting the output hydraulic chamber (12), and in normal times, the pressure receiving piston (13) and the receiving member (30) A spring (32) that separates a predetermined distance (14) from each other is contracted between the receiving member (30) and the pressure receiving piston (13), and is separated from the input hydraulic chamber (15) of the valve piston (16). A restriction piston (34), one end of which engages with the valve piston (16) to restrict the sliding limit to the valve piston (16), is slidably fitted in the cylinder hole (C). 16) Stopper part (30s) that regulates the sliding limit to the side
Is provided on the receiving member (30), and the restriction piston (34) is biased by the spring (36) to the engagement position with the stopper portion (30s), so that the master cylinder (M) and the front wheel brakes (Bfl, Bfr). Restricted hydraulic chamber (3
3) is defined between the other end of the restriction piston (34) and the other end wall of the housing (6),
Vehicle braking hydraulic control device.