JPH036022B2 - - Google Patents

Description

[Detailed Description of the Invention] A. Purpose of the Invention (1) Industrial Application Field The present invention provides an input hydraulic chamber communicating with an output port of a master cylinder, and a braking system communicating with a wheel brake according to the hydraulic pressure of the input hydraulic chamber. A brake hydraulic modulator has an output hydraulic chamber for generating hydraulic pressure, and is configured to increase the volume of the output hydraulic chamber in accordance with the supply of control hydraulic pressure to the control chamber when the wheels are about to enter a lock state. The present invention relates to a vehicle brake hydraulic control device disposed corresponding to each wheel brake.

(2) Conventional technology Conventionally, in such a brake hydraulic control device for a vehicle, each brake hydraulic modulator operates a piston according to the hydraulic pressure in the input hydraulic chamber to reduce the volume of the output hydraulic chamber. A braking hydraulic pressure corresponding to the hydraulic pressure is generated from the output hydraulic chamber, and during anti-lock, the piston is actuated in the opposite direction by the control hydraulic pressure supplied to the control chamber to increase the volume of the output hydraulic chamber.

(3) Problems to be solved by the invention In the above conventional vehicle brake hydraulic control device,
The brake hydraulic system is separated into two parts: from the master cylinder to the input hydraulic chamber, and from the output hydraulic chamber to the wheel brakes. Therefore, when supplying hydraulic oil to the brake hydraulic system, both are operated separately. It was necessary to fill it with oil. In addition, the piston is always in operation when the brake is operated, and the number of strokes is large, resulting in poor durability.

Therefore, the applicant has developed an anti-lock control system that integrates the braking hydraulic system from the master cylinder to the wheel brakes to facilitate the filling of hydraulic oil, as well as to reduce the number of piston strokes and improve durability. A hydraulic control device has already been proposed that includes a normally open valve mechanism that shuts off the output hydraulic chambers at the same time, and a brake hydraulic modulator that is installed on the partition wall between the output hydraulic chambers.

According to such a hydraulic control device, the above problems are solved. However, when the hydraulic pressure in the control chamber increases abnormally when the vehicle is traveling on a rough road or when excessive antilock control is performed due to failure of the antilock control valve means, the volume of the output hydraulic chamber becomes abnormally large. As a result, the pressure in the hydraulic system between the output hydraulic chamber and the wheel brakes becomes negative, which may cause so-called air trapping.

Additionally, since the braking load of a vehicle is generally larger on the front wheels and smaller on the rear wheels, it is desirable to reduce the braking oil pressure on the rear wheels, and for this purpose conventionally a proportional pressure reducing valve has been installed. However, it would be advantageous if the brake hydraulic modulator could function as a proportional pressure reducing valve.

Furthermore, since a relatively large amount of braking oil pressure is required on the front wheel side, the volume of the input oil pressure chamber is also set to be relatively large, and therefore the amount of oil returned from the input oil pressure chamber to the master cylinder during anti-lock braking is also reduced. This will be relatively large, and the amount of jerking that will occur in the brake pedal will also be large.

The present invention has been made in view of the above circumstances, and provides a front wheel brake hydraulic modulator that has a simple configuration, prevents the output hydraulic pressure chamber from becoming negative pressure, and reduces the amount of oil returned from the input hydraulic chamber to the master cylinder. To provide a brake hydraulic control device for a vehicle which prevents negative pressure in an output hydraulic chamber of a rear wheel brake hydraulic modulator with a simple configuration and also functions as a proportional pressure reducing valve. The purpose is to

B. Structure of the Invention (1) Means for Solving the Problems According to the present invention, in the front wheel brake hydraulic modulator, the first piston is fixed to one end of the piston rod that penetrates the partition wall oil-tightly and movably. the second piston is relatively movably attached to the other end of the piston rod and biased toward the partition wall;
Moreover, a valve mechanism is provided in the piston rod to communicate between the input hydraulic pressure chamber and the output hydraulic chamber in accordance with the relative proximity movement of the second piston to the partition wall. A first piston having a small diameter is fixed to one end of a piston rod that oil-tightly and movably penetrates the partition wall, and a second piston is mounted to the other end of the piston rod so as to be relatively movable and extends toward the partition wall. energized.

(2) Action In both the front wheel and rear wheel brake hydraulic modulators, the second piston applies pressure to the piston rod until the biasing force toward the bulkhead and the force directed away from the bulkhead caused by the hydraulic pressure in the output hydraulic chamber are balanced. Since the output hydraulic pressure chamber moves relative to the other, it is possible to avoid negative pressure in the output hydraulic chamber. Furthermore, in the front wheel brake hydraulic modulator, the input hydraulic chamber and the output hydraulic chamber communicate with each other as the second piston moves relatively close to the partition wall, so negative pressure in the output hydraulic chamber is more reliably prevented, and The amount of oil returning from the input hydraulic chamber to the master cylinder decreases. Furthermore, in the rear wheel brake hydraulic modulator, since the first piston has a smaller diameter than the second piston, it functions as a proportional pressure reducing valve.

(3) Embodiment An embodiment of the present invention will be described below with reference to the drawings. First, in FIG. 1, oil passages 2a and 2b are connected to a pair of output ports 1a and 1b of a tandem master cylinder Mc. , the output oil pressure from one output port 1a is supplied to the right front wheel brake oil pressure modulator Mfr and the left rear wheel brake oil pressure modulator Mrl via the oil path 2a,
The output oil pressure from the other output port 1b is oil passage 2b.
Brake hydraulic modulator for left front wheel via MFL
and the brake hydraulic modulator Mrr for the right rear wheel. The brake hydraulic modulators Mfl, Mfr for the left and right front wheels adjust the braking hydraulic pressure corresponding to the output hydraulic pressure of the master cylinder Mc to the brakes Bfl, Mfr for the left and right front wheels.
The brake hydraulic modulators Mrl and Mrr for the left and right rear wheels are the master cylinders.
Braking oil pressure proportionally reduced from Mc's output oil pressure is shown on the left.
It acts to apply brakes Brr and Brr for the right rear wheel.

In addition, in order to reduce the brake hydraulic pressure when each wheel is about to lock up, the brake hydraulic pressure source 5 and the reservoir R, the brake hydraulic pressure modulators Mfl and Mfr for the left and right front wheels, and the brake hydraulic pressure for the left and right rear wheels are connected. Antilock control valve means 6a and 6b are interposed between the modulators Mrl and Mrr. i.e. brake hydraulic modulator for left and right front wheels
The antilock operation of Mfl and Mfr is controlled by the operation of one antilock control valve means 6a,
Brake hydraulic modulator Mrl for left and right rear wheels,
The antilock of Mrr is controlled by the operation of the other antilock control valve means 6b.

In FIGS. 2 to 4, the brake hydraulic modulators Mfl, Mfr, Mrl, and Mrr are provided in a common casing 7. Moreover, the brake hydraulic modulators Mfl and Mfr for the left and right front wheels and the brake hydraulic modulators Mrl and Mrr for the left and right rear wheels are arranged parallel to each other. In addition, there are brake hydraulic modulators in the same hydraulic system, namely a brake hydraulic modulator Mfr for the right front wheel and a brake hydraulic modulator Mrl for the left rear wheel, to which hydraulic pressure is supplied from one output port 1a of the master cylinder Mc, and a brake hydraulic modulator Mrl for the left rear wheel, which is supplied with hydraulic pressure from one output port 1a of the master cylinder Mc. Brake hydraulic modulator Mfl for the left front wheel and brake hydraulic modulator for the right rear wheel, to which hydraulic pressure is supplied from output port 1b.
Brake hydraulic modulators Mfl, Mfr, Mrl, and Mrr are adjacent to each other on a parallel straight line.
Mrr is arranged. Furthermore, one anti-lock control valve means 6a is disposed on the extension of a straight line connecting the brake hydraulic modulators Mfl and Mfr for the left and right front wheels.
The other anti-lock control valve means 6b is arranged on the extension of a straight line connecting Mrl and Mrr, and both anti-lock control valve means 6a and 6b are integrally supported by a mounting portion 85 provided on the side of the casing 7. , their antilock control valve means 6a, 6b.
A reservoir R is disposed on top of the reservoir R.

Each brake hydraulic modulator Mfl, Mfr, Mrl,
Mrr extends vertically and is arranged parallel to each other, and is a brake hydraulic modulator for the left and right front wheels.
The configurations of Mfl and Mfr are basically the same, and the configurations of the brake hydraulic modulators Mrl and Mrr for the left and right rear wheels are basically the same as the brake hydraulic modulators Mfl and Mfr for the left and right front wheels, with some exceptions. It is.
Therefore, the structure of the brake hydraulic modulator Mfl for the left front wheel will be explained in detail below, and the brake hydraulic modulator Mrr for the right rear wheel will be explained in detail.
Only the parts that are different from the brake hydraulic modulators Mfl and Mfr for the right front wheel will be explained, and the main parts corresponding to the brake hydraulic modulator Mfl for the left front wheel will only be illustrated with the same reference numerals.

In FIG. 5, the left front wheel brake hydraulic modulator Mfl is constructed by assembling components from above into a bottomed cylinder hole 8 bored in the casing 7 and having an open upper end. That is, cylinder hole 8
A disk-shaped partition wall 9 and a cylindrical sleeve 10 are fitted inside. The partition wall 9 is fitted into the cylinder hole 8 with an O-ring 11 interposed between it and the inner surface of the cylinder hole 8, and the sleeve 10 is inserted into the cylinder hole 8 with an O-ring 13 interposed between it and the inner surface of the cylinder hole 8. It will be inserted into. In the middle of the cylinder hole 8 is a step 1 facing upward.
2 is provided. Further, a lid member 14 is attached to the casing 7 corresponding to the open end of the cylinder hole 8, and the partition wall 9 and the sleeve 10 are clamped and fixed between the lid member 14 and the step portion 12. Note that the sleeve 10 may be integrated with the partition wall 9.

By fixing the partition wall 9 and the sleeve 10 in the cylinder hole 8, the partition wall 9 is formed in the casing 7.
A first cylinder portion 15 located below the partition wall 9 and a second cylinder portion 16 located below the partition wall 9 are formed concentrically.

A first piston 17 is slidably connected to the first cylinder portion 15 , an input hydraulic pressure chamber 18 is defined between the first piston 17 and the partition wall 9 , and a control chamber 19 is defined between the bottom of the casing 7 and the first piston 17 . defined.

An annular oil passage 28 is defined between the lower outer surface of the partition wall 9 and the inner surface of the cylinder hole 8, and an oil passage 20 is bored in the partition wall 9 to communicate between the input hydraulic chamber 18 and the annular oil passage 28. will be established. Further, the casing 7 is provided with an inlet oil passage 21 that opens at the side surface 7a on the left front wheel brake hydraulic modulator Mfl side and communicates with the annular oil passage 28. Furthermore, the annular oil passage 2 is also connected to the brake hydraulic modulator Mrr for the right rear wheel.
8 is provided, and its annular oil passage 28 and the annular oil passage 2 of the brake hydraulic modulator Mfl for the left front wheel
8 through a communication passage 29, and this communication passage 29 is bored in the casing 7 on the axial extension of the inlet oil passage 21. Therefore, when processing the casing 7, the inlet oil passage 21 and the communication passage 29
are drilled at the same time. Moreover, the inlet oil passage 21
The open end of is the output port 1 of master cylinder Mc.
An oil passage 2b continuous to b is connected to the oil passage 2b. Therefore,
The output hydraulic pressure from the output port 1b is supplied to the input hydraulic chambers 18 of both brake hydraulic modulators Mfl and Mrr.

A second piston 22 having the same diameter as the first piston 17 is slid into the second cylinder portion 16 , an output hydraulic chamber 23 is defined between the second piston 22 and the partition wall 9 , and the second piston 22 and the lid member 14 are provided with an output hydraulic pressure chamber 23 . A spring chamber 24 is defined therebetween. An oil passage 25 is bored in the sleeve 10 so as to constantly communicate with an output oil pressure chamber 23, and a brake oil pressure modulator for the left front wheel Mfl.
The outlet oil passage 26 bored in the side wall of the casing 7 to connect the oil passage 3b (see Fig. 1) leading to the
The output oil pressure chamber 23 is bored through the oil passage 25, and the outlet oil passage 26 is opened on the side surface 7a of the casing 7 on the same side as the inlet oil passage 21.

The lid member 14 is basically formed into a cylindrical shape with a bottom, and its open end is screwed into the open end of the cylinder hole 8 and abuts against the sleeve 10. Moreover, the lid member 1
A hole 27 is bored at the closed end of 4.

A through hole 31 is bored in the center of the partition wall 9 between the input hydraulic chamber 18 and the output hydraulic chamber 23, and a piston rod 33 is inserted into the through hole 31 with an O-ring 32 interposed between the two. It is inserted so that it can move freely in the axial direction. The first piston 17 is integrally provided at the bottom of the piston rod 33, and the second piston 22 is sealed at the top of the piston rod 33 to allow relative axial movement within a limited range. It is attached with the member 34 interposed between the two. Further, a step portion 35 facing upward is integrally provided at the upper part of the piston rod 33, and a receiving member 36 that comes into contact with this step portion 35 is attached to the piston rod 33 by a nut 37.
is fixed at the top of the

The second piston 22 is integrally provided with a cylindrical portion 38 extending toward the partition wall 9, and this cylindrical portion 38
Corresponding to this, the piston rod 33 has an output hydraulic chamber 23.
A locking hole 39 is bored along one diameter line, and is in continuous communication with the. In addition, the locking hole 39 has a cross-sectional shape of an elongated oval along the axial direction of the piston rod 33, and is connected to the rod 4 fixed at one or both ends to the cylindrical portion 38 of the second piston 22.
0 is inserted into the locking hole 39. Therefore, the second piston 22 is allowed to move relative to the piston rod 33 within the range in which the rod 40 can move along the axial direction of the piston rod 33 within the locking hole 39.

A flange portion 42 is provided on the piston rod 33 on the side closer to the partition wall 9 than the first piston 17 , and this flange portion 42 contacts the partition wall 9 to restrict upward movement of the piston rod 33 . Also, the first piston 17
A sealing member 43 is fitted between the flange 42 and a blind lid 44 attached to the lower end of the piston rod 33.
A seal member 45 is provided between the first piston 17 and the first piston 17.
are fitted, and both seal members 43 and 45 come into sliding contact with the inner surface of the first cylinder portion 15. Furthermore, the second piston 22 has an annular fitting groove 4 in a portion near the partition wall 9.
6 is provided, and a sealing member 47 that comes into sliding contact with the inner surface of the second cylinder portion 16 is fitted into this fitting groove 46 .

The receiving member 36, that is, the piston rod 33 and the lid member 1
A first spring 48 is interposed between the first piston 17 and the first piston 4 , and the spring force of the first spring 48 biases the piston rod 33 downward, that is, in a direction in which the first piston 17 moves away from the partition wall 9 . Also, between the receiving member 36, that is, the piston rod 33, and the second piston 22, the first spring 48 is provided for exerting a spring force to relatively move the second piston 22 toward the partition wall 9.
A second spring 52 with a smaller set load is interposed.

The partition wall 9 is provided with a valve mechanism 53 that communicates and blocks communication between the input hydraulic chamber 18 and the output hydraulic chamber 23. The first valve mechanism 53 has a valve chamber 54 provided in the partition wall 9 that communicates with the input hydraulic chamber 18, a valve hole 55 provided between the valve chamber 54 and the output hydraulic chamber 23, and a valve hole 55 that opens and closes the valve hole 55. A spherical valve body 56 is preferably housed in the valve chamber 54, a drive rod 57 is integrated with the valve body 56 and passes through the valve hole 55 and faces the output hydraulic chamber 23, and a drive rod 57 is housed in the valve chamber 54. A spring 58 that urges the valve body 56 toward the valve hole 55 side is provided. Valve chamber 54
A conical valve seat 59 whose diameter becomes smaller toward the valve hole 55 side is provided on the end face on the valve hole 55 side. Further, the length of the drive rod 57 is the same as that of the second piston 22.
is set to a value sufficient to cause the valve element 56 to move away from the valve seat 59 by being pressed by the pressing part 60 provided at the tip of the cylindrical part 38 of the second piston 22 when the valve is displaced to the maximum extent toward the partition wall 9 side. be done.

Further, a second valve mechanism 61 is provided within the piston rod 33. This second valve mechanism 61 includes a valve chamber 62 that is always in communication with the input hydraulic pressure chamber 18, and a piston rod 33.
A cylindrical valve seat member 64 having a valve hole 63 concentric with
, a passage 65 concentrically connected to the valve hole 63 and communicating between the valve hole 63 and the locking hole 39 , and a spherical valve body 66 accommodated in the valve chamber 62 to open and close the valve hole 63 .
and a spring 67 that urges the valve body 66 toward the valve hole 63.
and a drive rod 68 inserted through the passage 65 and the valve hole 63 to press the valve body 66 and open the valve hole 63.

The valve chamber 62 is formed by fitting the valve seat member 64 into a bottomed hole concentrically formed in the lower end of the piston rod 33 and closing the open end of the bottomed hole with the blind cover 44. and a blind lid 44. The seal between the valve chamber 62 and the passage 65 is achieved by press-fitting and fixing the valve seat member 64 into the bottomed hole. It is also possible to intervene. A valve body receiver 69 that receives the valve body 66 is housed in the valve chamber 62 so as to be movable in the axial direction of the piston rod 33 , and a spring 67 is interposed between the blind cover 44 and the valve body receiver 69 . Further, a communication hole 70 that communicates between the valve chamber 62 and the input hydraulic pressure chamber 18 is bored in the piston rod 33 .

The length of the drive rod 68 is the same as that of the valve body 66 in the closed state.
When one end is in contact with the locking hole 39, the other end projects into the locking hole 39 by a certain length. Therefore, the second piston 22 is connected to the receiving member 3.
When the valve element 66 of the second valve mechanism 61 moves away from the valve seat member 64 and opens relative to the piston rod 33 over a certain distance in a direction away from the valve seat member 64 and closer to the partition wall 9.

Regarding the brake hydraulic modulator Mrr for the right rear wheel, the second valve mechanism 61 is omitted, and the first piston 17' is set to have a smaller diameter than the second piston 22, and the first cylinder portion 15 is adjusted accordingly. ′ becomes smaller. Moreover, the set load of the first spring 48' is set larger than that of the first spring 48 of the brake hydraulic modulator Mfl for the left front wheel, and the first spring 48' is larger than the first spring 48. Accordingly, the lid member 14' also becomes larger.

The other structure of the brake hydraulic modulator Mrr for the right rear wheel is basically the same as that of the brake hydraulic modulator Mfl for the left front wheel.
6' is a side surface 7a of the casing 7 adjacent to the outlet oil passage 26 of the brake hydraulic modulator Mfl for the left front wheel.
The outlet oil passage 26' is connected to an oil passage 4b (see FIG. 1) leading to the right rear wheel brake Brr.

The brake hydraulic modulator Mfr for the right front wheel and the brake hydraulic modulator Mrl for the rear left wheel are configured in the same manner as described above. hydraulic modulator
The outlet oil passages 72 and 72', which communicate with the output hydraulic chambers 23 of Mfr and Mrl, respectively, are the same as the inlet oil passage 21 and the outlet oil passages 26 and 26'.
It is opened on the side surface 7a of. An oil passage 2a is connected to the inlet oil passage 71, and oil passages 3a and 4a are connected to the outlet oil passages 72 and 72', respectively.

The lower part of the casing 7 has a supply oil passage 73a communicating with the control chamber 19 of the brake hydraulic modulators Mfl, Mfr for the left and right front wheels, and a control chamber 19 of the brake hydraulic modulators Mrl, Mrr for the left and right rear wheels. The supply oil passage 73b is bored in a straight line and in parallel, and the supply oil passages 73a, 73b
One end of the opening is closed with lids 74a and 74b.
Both supply oil passages 73a, 73b are for supplying control hydraulic pressure to each control chamber 19, and the other ends of the supply oil passages 73a, 73b are for supplying control hydraulic pressure via anti-lock control valve means 6a, 6b. connected to source 5.

Referring again to FIG. 1, the control fluid pressure source 5 consists of a hydraulic pump P that pumps control fluid, such as hydraulic oil, from a reservoir R, and an accumulator AC.
Hydraulic pump P is driven as necessary during vehicle operation. Further, the control hydraulic pressure source 5 is provided with a hydraulic pressure sensor S for detecting failures and oil pressure failures of the hydraulic pump P, as well as the start and stop of driving the hydraulic pump P.

The anti-lock control valve means 6a, 6b consists of first solenoid valves V1a, V1b which are closed during normal times and second solenoid valves V2a, V2b which are open during normal times, and when each wheel is about to lock, 1st
The solenoid valves V1a and V1b are driven to open, and the second solenoid valves V2a and V2b are driven to close.

The first solenoid valves V1a and V1b are supply oil passages 73a,
73b, and the second solenoid valve V2
a, V2b are provided in the middle of return oil passages 75a, 75b that branch from the supply oil passages 73a, 73b and reach the reservoir R between the first electromagnetic valves V1a, V1b and the control chamber 19.

Further, the first solenoid valves V1a, V1b and the second solenoid valves V2a, V2b have a cylindrical housing 76a,
The housings 75a and 75b are stacked in a stacked manner, and a reservoir R is disposed above the housings 75a and 75b.

Each brake hydraulic modulator Mfl, Mfr, Mrl,
A cap 77 is fitted to the upper end of the casing 7 so as to cover the lid members 14 and 14' of the Mrr, and the upper surface of the cap 77 has supporting parts 78a and 78b having an arcuate cross section and an open top. is provided. Each support portion 78a, 78b includes a respective electromagnetic valve V1a, V of both anti-lock control valve means 6a, 6b.
1b; Connection members 79a and 79b for connecting wiring to V2a and V2b are fitted and held, respectively.

Next, the operation of this embodiment will be explained.First, the brake hydraulic modulators Mfl and Mfr for both front wheels will be explained.
To explain the action of the piston rod 33, when the brake pedal 83 is not operated and the brake pedal 83 is not operated, the piston rod 33 is moved downward by the spring force of the first spring 48, and the second piston 22 is in contact with the partition wall 9. ing. Therefore, in the first valve mechanism 53, the drive rod 57 is connected to the pressing portion 60 of the second piston 22.
The valve element 56 is separated from the valve seat 59 and opened. Therefore, the master cylinder
Input hydraulic chamber 18 from output ports 1a and 1b of Mc,
Valve chamber 54, valve hole 55, output hydraulic chamber 23, oil passage 2
5. Outlet oil passages 26, 26' and oil passages 3a, 3b
A hydraulic path is formed through the brakes Bfl and Bfr. This makes it possible to extremely easily fill the brake hydraulic system with hydraulic oil, similar to a brake hydraulic system not equipped with a brake hydraulic control system for anti-lock control. That is, whereas conventionally, the hydraulic path from the master cylinder Mc to the input hydraulic chamber 18 and the hydraulic path from the output hydraulic chamber 23 to the brakes Bfl and Bfr had to be separated and filled with hydraulic oil. , master cylinder
A brake hydraulic path is established from Mc to both front wheel brakes Bfl and Bfr, so the master cylinder
By filling hydraulic oil from the Mc side, filling of hydraulic oil to both brakes Bfl and Bfr is completed.

When the brake pedal 83 is used to perform a brake operation, the output ports 1a and 1b of the master cylinder Mc
The braking hydraulic pressure from the
Supplied to Bfl and Bfr. At this time, since the control fluid pressure from the control fluid pressure source 5 is not supplied to the control chamber 19, the second piston 22 remains displaced to the maximum extent toward the partition wall 9 by the spring force of the first spring 48.
The first valve mechanism 53 remains closed. In this way, the braking oil pressure is transferred from the master cylinder Mc to each brake.
Since it is directly supplied to Bfl and Bfr, the piston stroke switch that was conventionally installed to detect brake hydraulic pressure leakage is omitted, and the hydraulic pressure is controlled by the same means as a brake hydraulic system that does not have an anti-lock control function. Leakage can be detected.

If the braking force becomes excessive during brake operation and the wheels are about to lock, the second solenoid valve V2
Since the first solenoid valve V1a is closed and the first solenoid valve V1a is opened, antilock control hydraulic pressure from the control hydraulic pressure source 5 is supplied to the control chamber 19. As a result, the first piston 17 and the piston rod 33 are pushed upward against the downward force generated by the first spring 48 and the hydraulic pressure of the input hydraulic chamber 18 . At this time, the second piston 22 moves upward together with the piston rod 33 while in contact with the receiving member 36 until the upward force due to the hydraulic pressure of the output hydraulic chamber 23 and the downward force due to the second spring 52 are balanced. Along with this, the second piston 22 separates from the partition wall 9, so that the valve body 56 of the first valve mechanism 53
is seated on the valve seat 59 and closed, cutting off the supply of braking hydraulic pressure to both brakes Bfl and Bfr, and increasing the volume of the output hydraulic pressure chamber 23. As a result, the brake hydraulic pressure is reduced and the wheels are prevented from locking up.

Here, the operation during excessive anti-lock control such as when driving on a rough road or when the control hydraulic pressure source 5 is out of order will be explained. First, during non-braking, the first piston 17 and the piston rod 33 move upward against the spring force of the first spring 48 as the control fluid pressure in the control chamber 19 increases, but the second piston 22 moves upward. The upward movement is restrained by the second spring 52, and the second piston 22 moves downward relative to the piston rod 33. As a result, in the second valve mechanism 61, the rod 40 integrated with the second piston 22 presses the drive rod 68, and the valve body 66 separates from the valve seat member 64 to open the valve. Therefore, the input hydraulic pressure chamber 18 and the output hydraulic pressure chamber 23 are communicated with each other, and the inside of the output hydraulic pressure chamber 23 is prevented from becoming a negative pressure that would be inconvenient for practical use. At this time, the relative movement between the second piston 22 and the piston rod 33 is until the rod 40 comes into contact with the side wall of the locking hole 39, and from then on, the second piston 22 moves upward together with the piston rod 33.

When a braking operation is performed in such a state, the braking oil pressure supplied from the master cylinder Mc to the input oil pressure chamber 18 is transferred to the output oil pressure chamber 2 via the second valve mechanism 61.
3, and both brakes are connected via oil passages 3a and 3b.
Acts on Bfl and Bfr. At this time, the output hydraulic chamber 23
When the upward force of the second piston 22 due to the hydraulic pressure of The same operation is performed.

Next, assume that the control fluid pressure in the control chamber 19 abnormally increases during braking. In this case, the piston rod 33 moves upward, and accordingly, the second piston 22 receives the upper power from the hydraulic pressure of the output hydraulic chamber 23 and the second
It moves upward together with the piston rod 33 until the downward force due to the spring force of the spring 52 is balanced. When the piston rod 33 further moves upward, the second piston 22 moves upward as the hydraulic pressure in the output hydraulic chamber 23 decreases.
3, and the second valve mechanism 61 opens. This prevents the oil pressure in the output oil pressure chamber 23 from dropping to a negative pressure that would pose a practical problem. Further, since the amount of oil in excess of the amount of oil required to be removed from the input hydraulic chamber 18 for proper anti-lock is led to the output hydraulic chamber 23, the brake pedal 83 is subjected to more kickback than is required for anti-lock control. It will never occur.

Brake hydraulic modulator for both rear wheels Mrl, Mrr
basically operates in the same way as the brake hydraulic modulators Mfl and Mfr for both front wheels, but the pressure receiving area of the first piston 17' is set smaller than the pressure receiving area of the second piston 22. Braking oil pressure reduced in proportion to the oil pressure in the input oil pressure chamber 18 can be output from the output oil pressure chamber 23, and functions as a proportional pressure reducing valve. Therefore, the output hydraulic pressure of master cylinder MC is proportionally reduced and supplied to both rear wheel brakes Brl and Brr.

In addition, brake hydraulic modulators for both rear wheels
Although Mrl and Mrr do not have the second valve mechanism 61, the first piston 18 has a small diameter and the input hydraulic chamber 1
Since the volume of the brake pedal 8 is also small, even during anti-lock excessive control, the amount of oil returned from the input hydraulic chamber 18 to the master cylinder Mc is small, so that no excessive jerking occurs in the brake pedal 83.

C. Effects of the Invention As described above, according to the present invention, in both the front wheel and rear wheel brake hydraulic modulators, the second piston is mounted on the piston rod so as to be relatively movable, and the second piston is biased toward the partition wall. I did it like this,
It is possible to prevent the output hydraulic pressure chamber from decreasing to a negative pressure that would cause a practical problem.

In addition, in the front wheel brake hydraulic modulator,
Since the piston rod is provided with a valve mechanism that communicates between the input hydraulic chamber and the output hydraulic chamber in accordance with the relative proximity movement of the second piston toward the partition wall side, negative pressure in the output hydraulic chamber can be more reliably prevented. At the same time, it is possible to reduce the amount of oil returned to the master cylinder and prevent excessive backlash from occurring.

Further, in the rear wheel brake hydraulic modulator, since the first piston has a smaller diameter than the second piston, it can also function as a proportional pressure reducing valve.

[Brief explanation of drawings]

The drawings show one embodiment of the present invention; the first is an overall hydraulic system diagram, the second is a front view, the third is a plan view of FIG. 2, and the fourth is a right side view of FIG. FIG. 5 is an enlarged sectional view taken along the - line in FIG. 2. 7...Casing, 8...Cylinder hole, 9...
Partition wall, 15, 15'...first cylinder part, 16...
...Second cylinder section, 17, 17'...First piston, 18...Input hydraulic chamber, 19...Control chamber, 22
...Second piston, 23...Output hydraulic chamber, 53...
...first valve mechanism, 61...second valve mechanism, Bfl, Bfr,
Brl, Brr...Wheel brake, Mc...Master cylinder, Mfl, Mfr...Front wheel brake hydraulic modulator, Mrl, Mrr...Rear wheel brake hydraulic modulator.

Claims (1)

[Claims] 1. A partition wall is provided in the middle of a cylinder hole drilled in the casing to divide the cylinder hole into a first cylinder part and a second cylinder part, and a partition wall defines an input hydraulic chamber communicating with the master cylinder in the first cylinder part. A first piston that defines a control chamber on the opposite side of the partition wall and that can communicate with a control hydraulic pressure source is slidably connected to the second cylinder portion, and an output hydraulic chamber that communicates with the wheel brakes is provided on the partition wall side of the second cylinder portion. A second piston is slidably connected to the first piston, and the partition wall is provided with a valve mechanism that shuts off the input hydraulic chamber and the output hydraulic chamber in response to movement of the first piston toward the partition wall. In the brake hydraulic control device for a vehicle, a brake hydraulic modulator for a front wheel is arranged to correspond to each wheel brake, and the first piston is a piston that penetrates a partition wall oil-tightly and movably. The second piston is fixed to one end of the rod, and the second piston is relatively movably attached to the other end of the piston rod and biased toward the partition wall.
A valve mechanism is provided to communicate between an input hydraulic pressure chamber and an output hydraulic pressure chamber in accordance with the relative proximity movement of the piston to the partition wall. A vehicle characterized in that the second piston is fixed to one end of a piston rod passing through the piston rod tightly and movably, and the second piston is relatively freely attached to the other end of the piston rod and is biased toward the partition wall. Brake hydraulic control device.