JPH03132455A - Anti-lock brake modulator - Google Patents

Abstract

PURPOSE:To improve responsiveness and make an anti-lock mechanism survivable as long as possible at the time of failure by providing a fixing mechanism for fixing a modulator piston so that a piston opens a cutoff valve at the pressure reducing time of an accumulator. CONSTITUTION:In an anti-lock brake modulator, a first and a second pistons 7, 13 of different diameters provided at both ends of a modulator piston 6 piercing a partition wall 5 are fitted into a first and a second cylinder parts 3, 4 with the partition wall 5 interposed in between. The outside of these pistons 7, 13 are formed into a control chamber 9 and a spring chamber 12 communicated respectively with an accumulator 33. The partition wall 5 is provided with a cutoff valve 16 closed at the time of anti-lock control operation to cut off the communication between an input and an output oil pressure chambers 8, 14. In this case, there is provided with a second cutoff valve 23 for fixing the modulator piston so that the second piston 13 opens the cutoff valve 16 at the pressure reducing time of the accumulator 33, and the second cutoff valve 23 is switched by the operation of a differential pressure piston 22.

Description

DETAILED DESCRIPTION OF THE INVENTION A0 OBJECTS OF THE INVENTION (1) Industrial Field of Application The present invention relates to a modulator for controlling brake hydraulic pressure transmitted from a master cylinder to wheel brakes in an anti-lock brake system for a vehicle.

(2) Conventional technology Conventionally, a modulator piston is attached to the modulator of an anti-lock brake system and controls a cut valve that controls communication/cutoff between the input hydraulic chamber communicating with the master cylinder and the output hydraulic chamber communicating with the wheel brakes. has one end facing the control chamber that receives control hydraulic pressure via a solenoid valve, and the other end is a spring with a strong pressing force installed in a spring chamber open to the atmosphere that keeps the cut valve in communication. The structure is such that when the anti-lock control is activated, the control chamber is pressurized to drive the modulator piston and control the cut valve to close. 17164
(See Publication No. 9).

(3) Problems to be Solved by the Invention However, in the conventional anti-lock brake modulator described above, the control chamber is normally maintained at atmospheric pressure, and the spring is pressed to a high level after the solenoid valve is activated due to the start of anti-lock control. In order to obtain pressurization of the fairly high pressure control chamber and to obtain sufficient responsiveness, since the modulator piston begins to move as the pressurization of the control chamber with a fairly high pressure is started against the pressure, and to obtain sufficient responsiveness. It was necessary to increase the rigidity and capacity of pumps and accumulators, and to make them larger.

In addition, it is desired to improve the functions such as allowing the anti-lock function or the proportional pressure reducing valve function (hereinafter referred to as the PCV function) to remain as much as possible even in the event of a failure.

The present invention was made in view of the above-mentioned circumstances, and has excellent responsiveness, and also has an anti-lock function or a PC control function when a failure occurs.
It is an object of the present invention to provide a modulator for anti-lock brakes that allows the V function to remain as much as possible.

B1 Structure of the Invention (1) Means for Solving the Problems In order to achieve the above object, the present invention provides a structure in which a first cylinder part and a second cylinder part are coaxially formed with a partition wall in between, and the partition wall is slidable. A first piston that is provided at both ends of a modulator piston that freely moves through the modulator piston and that slides into the first cylinder portion and the second cylinder portion, respectively, and a second piston that has a larger pressure receiving area than the first piston, and the first piston. a cavity control chamber defined on the outside of the second piston and communicating with the accumulator; a spring chamber defined on the outside of the second piston and communicating with the accumulator and having a spring contracted therein; and the partition wall and the first piston. an input hydraulic chamber defined between and communicating with the master cylinder;
an output hydraulic chamber defined between the pistons and communicating with the wheel brake; and an output hydraulic chamber provided in the partition wall, which opens when the second piston comes into contact during normal braking, and communicates the input hydraulic chamber with the output hydraulic chamber; In an anti-lock brake modulator, the anti-lock brake modulator includes a cut valve that closes when the second piston separates during anti-lock control operation to cut off communication between the input hydraulic pressure chamber and the output hydraulic chamber, when the pressure in the accumulator is reduced. , the second piston is driven to open the cut valve based on a modulator piston fixing mechanism that fixes the modulator piston, and a differential pressure between a master cylinder side hydraulic pressure and a wheel brake side hydraulic pressure when antilock control is activated; and a differential pressure piston that disables the modulator piston fixing mechanism.

(2) Function According to the feature of the present invention described above, when the accumulator is in the pressure accumulation state, the control hydraulic pressure acts on the control chamber and the spring chamber at both ends of the modulator piston, and the first piston and the second piston The second piston is held in a position where the cut valve is opened due to the difference in the pressure receiving area of the second piston. As a result, the input hydraulic chamber and the output hydraulic chamber communicate with each other to form a hydraulic path from the master cylinder to the wheel brakes. When the control oil pressure in the splash chamber is removed during anti-lock control operation, the first piston is pressed by the control oil pressure in the control chamber to drive the modulator piston, and the second piston moves away from the cut valve to perform the cut. Close the valve. This blocks communication between the input hydraulic chamber and the output hydraulic chamber, increases the volume of the output hydraulic chamber, reduces the wheel brake side hydraulic pressure, and prevents the wheels from entering a locked state.

When the accumulator is depressurized due to a failure, the modulator piston fixing mechanism is activated and the modulator piston is fixed, so the second piston is held in a position where the cut valve is forcibly opened, allowing normal braking to continue as before. continues.

However, if the pressure in the accumulator is reduced during anti-lock control operation, the master cylinder side oil pressure is greater than the wheel brake side oil pressure, so the differential pressure piston is driven and the modulator piston fixing mechanism becomes inactive, and the modulator piston Anti-lock control is performed as long as the control oil pressure remains in the accumulator, and after the control oil pressure completely disappears, braking is performed with the gain reduced by the PC■ function.

(3) Examples Hereinafter, the present invention will be explained in detail based on the drawings.

FIG. 1 shows a first embodiment of the present invention, in which a modulator M is installed between a master cylinder Cm driven by a brake lever 1 attached to a handle of a motorcycle and a caliper cylinder 00 attached to a wheel. ing.

Inside the modulator body 2, a small-diameter first cylinder part 3 and a large-diameter second cylinder part 4 are coaxially formed.
A modulator piston 6 is slidably fitted into a partition wall 5 that partitions both cylinder parts 3.4. The first piston 7 is fixed to the left end of the mojip rake piston 6 and slides into the small diameter first cylinder part 3. The first cylinder part 3 is connected to the input hydraulic chamber 8 connected to the master cylinder Cm, and the control chamber 9. It is defined as 0. On the other hand, the right end of the modulator piston 6 is integrally formed with a spring seat 10 that slides into the large-diameter second cylinder portion 4, and a spring 11 that urges the modulator piston 6 leftward is compressed on the right side of the spring seat 10. A splash chamber 12 is defined. A second piston 13 slidably supported on the outer periphery of the intermediate portion of the modulator piston 6 is fitted inside the large-diameter second cylinder portion 4, and between the second piston 13 and the partition wall 5, the An output hydraulic chamber 14 connected to the caliper cylinder CC is defined.

Spring seat 10 of modulator piston 6 and second piston 1
3, there is a spring 11 housed in the spring chamber 12.
The spring 15 is compressed with a set load that is weaker than that of the second piston 13, and urges the second piston 13 toward the partition wall 5. This prevents negative pressure from being generated in the output hydraulic chamber 14 even if the modulator piston 6 suddenly moves to the right.

The first cut valve 16 that controls communication and isolation between the input hydraulic chamber 8 and the output hydraulic chamber 14 includes a valve body 17 in which a shaft portion 17a is loosely fitted into a through hole 5a formed in the partition wall 5. The valve body 17 is biased rightward by a valve spring 18.
This valve body 17 forms a valve seat 5b at the entrance of the through hole 5a.
The first cut valve 16 is closed by sitting on the seat. Further, when the shaft portion 17a protruding into the output hydraulic pressure chamber 14 is pressed by the second piston 13 at the left end position and moves to the left, the valve body 17 is separated from the valve seat 5b and the first cut valve 16 is opened. .

The modulator body 2 further has a cylinder 19 and a hole 20 coaxially formed therein. The cylinder 19 and the hole 20 accommodate a differential pressure piston 22 connected by a rod 21 and moving together, and a second cut valve 23 as a modulator piston fixing mechanism. The first chamber 24 on the left side of the differential pressure piston 22 communicates with the input hydraulic chamber 8 , and the second chamber 25 on the right side thereof communicates with the output hydraulic chamber 14 .

On the other hand, the second cut valve 23 includes a valve body 28 that is urged by a valve spring 26 in a direction to contact the valve seat 27, and opens when the rod 21 moves to the right against the valve spring. .

The cylinder 29 formed in the modulator body 2 is provided with an accumulator 33 consisting of an accumulator chamber 30, an accumulator piston 31, and an accumulator spring 32.

When the accumulator chamber 30 enters the pressure accumulation state, the accumulator piston 31 moves to the right while compressing the accumulator spring 32, presses the rod 21, and opens the second cut valve 23.

A hydraulic pump 34 that generates control hydraulic pressure is connected to the accumulator chamber 3 of the accumulator 33 via an oil passage L3.
0, and further connected to a normally open inlet valve 35 made of a solenoid valve via an oil path L2. The inlet valve 35 is connected to a normally closed outlet valve 36 via an oil passage L3, and is further connected to a low pressure oil passage L4 from there.
It is connected to the hydraulic pump 34 via. The control chamber 9 facing the first piston 7 of the modulator piston 6 is connected to the hydraulic pump 34 via an oil path, and the spring chamber 12 facing the spring seat 10 is connected to the oil path L7, the second cut valve 23, It is connected to the oil passage L3 via an oil passage L6. As a result, when the second cut valve 23 is in the open state, the control hydraulic pressure accumulated in the accumulator 30 acts on the first piston 7 of the modulator piston 6 and the second piston 13 in contact with the spring seat 10. do.

The electronic control device 37 includes a wheel speed sensor 3 that detects when the wheels are in a locked state.
8 detection signals are input, and the inlet valve 35 and outlet valve 36 are controlled based on the calculation results of the signals. Further, an accumulator sensor 39 provided at the end of the rod 21 is connected to the electronic control device 37, and when the accumulated pressure of the accumulator 33 decreases due to leakage and the accumulator piston 31 and the rod 21 move to the left, , the hydraulic pump 34 is driven to accumulate pressure in the accumulator 33.

Next, the operation of the embodiment of the present invention having the above-described configuration will be explained.

When the ignition switch is OFF, the hydraulic pump 34 is stopped and both the inlet valve 35 and outlet valve 36 are open, so the accumulator chamber 3 is in a low pressure state and the accumulator piston 31
is moving to the left by the elastic force of the accumulator spring 32. As a result, the restriction on the left end of the rod 21 is released, and the valve body 28 is seated on the valve seat 27 by the elastic force of the valve spring 26.
The second cut valve 23 is closed. As a result, the splash chamber 12 enters an oil lock state, the modulator piston 6 is held at a position where the first cut valve 16 is forcibly opened, and a state where normal braking is possible is maintained.

When the ignition switch is turned on, the outlet valve 36 closes and the hydraulic pump 34 operates simultaneously, causing pressure to be accumulated in the accumulator 33 via the oil path L1. As a result, the accumulator piston 31 moves to the right, presses the °ζ rod 21 to the right, and the second cut valve 2
3 opens ↑.

Further, the pressure oil in the accumulator 33 that has been accumulated is transferred to the oil path I7□, the inlet valve 35, the oil path L3, the oil path ■,
6. Pressurize the spring chamber 12 via the second cut valve 23 and the oil passage 1-7. At this time, since the pressure receiving area of the spring seat lOO formed at the right end is larger than the pressure receiving area of the first piston 7 fixed to the left end of the modulator piston 6, the modulator piston 6 opens the first cut valve 16. Stops at the leftmost position. Therefore, when the first cut valve 16 is opened, the master cylinder C
The master cylinder side hydraulic pressure I) generated at m is supplied to the input hydraulic chamber 8, the first cut valve 16, and the output hydraulic chamber 14.
The hydraulic pressure is transmitted to the caliber cylinder CC as a wheel brake side hydraulic pressure Pz (=P+), and normal braking is performed.

When the wheel speed sensor 38 detects that the wheel is about to enter the locked state, the inlet valve 35 is closed and the outlet valve 36 is opened according to a command from the electronic control unit 37, and the inside of the spring chamber 12 is opened. The pressure is reduced by communicating with the low pressure oil passage L4 via the outlet valve 36.

At this time, the modulator piston 6 is pressed by the first piston 7 sliding into the pressurized control chamber 9 and quickly moves to the right against the spring 11. the result,
The second part is fitted to the modulator piston 6 so as to be relatively movable.
The piston 13 is moved rightward by the wheel brake side hydraulic pressure P2 in the output hydraulic pressure chamber 14 to open the first cut I/valve 1.
6 is closed, and the volume of the output hydraulic pressure chamber 14 is increased to decrease the wheel brake side hydraulic pressure P2, thereby preventing the wheels from entering the locked state. Also, when the pressure increases, the outlet valve 36 closes and the inlet valve 35 opens as much as necessary, so that the splash chamber 12 is pressurized, and the modulator piston 6 and second piston 13 move to the left as a unit to move toward the wheel brake side. Increase oil pressure P2.

~ 18 Now, when the control hydraulic pressure decreases due to a failure of the hydraulic pump 34 or the accumulator 30 during normal braking, the accumulator piston 31 moves to the left by the elastic force of the brake spring 320, and the rod released from the restraint by the accumulator piston 31 moves to the left. 21 is moved to the left by the elastic force of the valve spring 26, and the second cut valve 23, which serves as a modulator piston fixing mechanism, is closed. As a result, the honey chamber 1
2 is in an oil lock state and the modulator piston 6
stops at the left end position, and the first cant valve 16 is kept open. In this way, even if the control hydraulic pressure fails during normal braking, the normal braking function is maintained.

On the other hand, when the control oil pressure decreases when the anti-lock control is activated, the accumulator piston 31 moves to the left as described above, but at this time, the master cylinder side oil pressure 1] is larger than the wheel brake side oil pressure P2, so the differential pressure The piston is driven rightward and the second cut valve 23 is kept open. As a result, the oil locking of the splash chamber 12 is prevented, the modulator piston 6 remains movable, and the anti-lock function is maintained as efficiently as possible until the amount of accumulated pressure in the accumulator 30 becomes zero. .

When the amount of accumulated pressure in the accumulator 30 becomes zero, the anti-lock function is lost, but the PCV function reduces the wheel brake side oil pressure P2 with respect to the master cylinder side oil pressure P to prevent the wheels from entering a locked state as much as possible. do.

That is, the effective cross-sectional area of the input hydraulic chamber 8 is A1, and the effective cross-sectional area of the 14 output hydraulic chambers is A2 (AI < A2).
, if the elastic force of the spring II stored in the spring chamber 11 is F, then the force pushing the modulator piston 6 to the left is P+
A, 10F, and the force pushing the modulator piston 6 to the right becomes P2A2. Here, by operating the brake lever 1, the master cylinder side oil pressure P 1 (= P z)
increases, and the differential pressure between P+AI and P2A2 becomes spring 1.
When the elastic force F of 1 is exceeded, the modulator piston 6 moves to the right, the first cut valve 16 closes, and the wheel brake side hydraulic pressure P2 of the output hydraulic chamber 14 decreases. As a result, the modulator piston 6 moves to the left by the elastic force of the spring 11, opening the first cut valve 16 again. When the master cylinder side oil pressure P1 further increases, the modulator piston 6 moves to the right and the first cut valve 16 closes in the same manner as described above. By vibrating the modulator piston 6 left and right in this way, the fourth
As shown in the figure, the wheel brake side oil pressure P2, which has increased by the same amount as the master cylinder side oil pressure P, increases by 1 when it passes the turning point P determined by the magnitude of the elastic force of the spring 11. The rate decreases and gain down occurs. This results in
Even after the anti-lock function is lost, the wheels are prevented from entering the locked state as much as possible by reducing the gain of the wheel brake side oil pressure P2 by the PC (2) function.

FIG. 2 shows a modification of the first embodiment. In this modification, the caliper cylinder Cc is pivotally supported on the vehicle body by a pin 40, and the tip of an arm 1141 extending from the pin 40 is at the right end of the modulator piston 6, which penetrates the modulator body 2 in a fluid-tight manner. is connected to.

Therefore, when the wheels are about to slip during the PCV function, the reaction force that the caliper cylinder Cc receives from the wheels, that is, the pressing force f by which the arm 41 provided on the caliper cylinder Cc presses the modulator piston 6 to the left, is equal to the road surface. It changes depending on the state. This pressing force f varies depending on the coefficient of friction of the road surface, and becomes large when the coefficient of friction is large and small when the coefficient of friction is small. As a result, in accordance with the change in the pressing force f, the force exerting the force on the modulator piston 6 in response to the input increases or decreases in conjunction with the spring 11 housed in the spring chamber 12, and as shown in the fifth leap, the master Cylinder side oil pressure P
The position of the corner point where the increase rate of the wheel brake side oil pressure P2 with respect to 1 starts to decrease changes to 1'+, Pz. In this way, the gain reduction becomes more noticeable on slippery road surfaces, so that the PCV function is more effectively exhibited.

FIG. 3 shows a second embodiment of the invention.

In this embodiment, the modulator piston 6 is fixed by oil-locking the splash chamber 12 in the first embodiment, whereas the accumulator piston 6 is fixed in this embodiment.
The modulator piston 6 is directly fixed to the modulator piston 6 by the piston rod 43 as a modulator piston fixing mechanism.
It is characterized by the fact that it is fixed. In this example,
Components that correspond to the components of the first embodiment and have the same functions are designated by the same reference numerals, and redundant explanation thereof will be omitted.

This embodiment includes an accumulator piston 31 disposed coaxially with the modulator piston 6 inside the modulator body 2 . A locking piston 44 formed at the intermediate portion of a piston rod 43 integral with the accumulator piston 31 is slid into a cylinder 42 connected to the cylinder 29 housing the accumulator piston 31, and the tip of the piston rod 43 is It reaches the inside of the splash chamber 12 and faces the end of the modulator piston 6. A locking chamber 45 is defined inside the cylinder 42 by a locking piston 44 . The locking chamber 45 is the oil path I! , I to the hydraulic pump 34, and the oil path β2. ! 3 to the accumulator chamber 30 of the accumulator 33. A differential pressure piston 2 is located between the oil passage 12 and the oil passage β3.
A second cut valve 23 driven by the differential pressure piston 22 is interposed, and this second cut valve 23 is driven by the differential pressure piston 22
When the master cylinder side oil pressure P1 acting on the first chamber 24 formed on both sides of the wheel is larger than the wheel brake side oil pressure P2 acting on the second chamber 25, the valve is closed and the locking chamber 45 is closed.

The accumulator chamber 30 of the accumulator 33 is connected to the oil passage 14
, is connected to the low-pressure side oil path r6 via the inlet valve 35, oil path β9, and outlet valve 36, and further branches from the oil path I! , 7 is in the control room 9, oil line I! , 5 is in communication with the spring chamber 12.

Therefore, when the ignition switch is OFF, the accumulator chamber 30 is in a low pressure state, and the accumulator spring 32
The first cut valve 16 is forcibly opened as the piston rod 43 protrudes into the spring chamber 12 and fixes the modulator piston 6, thereby maintaining a state in which normal braking is possible.

When the ignition switch is turned on, the outlet valve 36 closes and the hydraulic pump 34 starts operating, and the oil path i! , 1. Pressure is accumulated in the accumulator chamber 3 through the locking chamber 45 and the second cutter (valve 23, and the accumulator piston 31 and the piston rod 43)
2 and release the modulator piston 6. Furthermore, the control hydraulic pressure accumulated in the accumulator 33 is transferred to the oil passages 1a, j!
s, 1. control room 9 and spring room 12 via r, 7!8
The modulator piston 6 is lowered to maintain a state in which normal braking is possible. When anti-lock 26 control is performed from this state, the effect is the same as in the first embodiment.

When the control hydraulic pressure fails during normal braking, the accumulator piston 31 descends due to the elastic force of the accumulator spring 32, and the oil in the accumulator chamber 30 pushes open the second cut valve 23 and flows from the locking chamber 45 to the low pressure side. Reflux to. As a result, the piston rod 43 is lowered by the elastic force of the accumulator spring 32 to lock the modulator piston 6, and the first cut valve 16 is maintained in the open state. In this way, even if the control hydraulic pressure fails during normal braking, the normal braking function is maintained.

On the other hand, if the control oil pressure fails during anti-lock control operation, the master cylinder side oil pressure P1 is larger than the wheel brake side oil pressure P2, so the differential pressure piston is driven to the left, and the second cut valve 23 is closed. do. This results in
The accumulator chamber 30 is closed and the piston rod 43
cannot be lowered, and the modulator piston 6 is prevented from being restrained.

As in the previous embodiment, the anti-lock function is maintained as efficiently as possible until the amount of pressure accumulated in the accumulator 30 becomes zero, and the amount of accumulated pressure in the accumulator 30 becomes zero. After that, 1) the C■ function prevents the wheels from entering the locked state as much as possible.

C3 Effects of the Invention As described above, according to the present invention, since the control hydraulic pressure is always acting on the control chamber that presses the modulator piston to close the cut valve when the anti-lock control is activated, the pressing force of the spring is reduced. Therefore, the control hydraulic pressure itself can also reduce the high pressure level. This makes it possible to downsize pumps, accumulators, etc., and to improve responsiveness by quickly driving the modulator piston. Also, when the anti-lock control is activated,
- When the modulator is depressurized, the differential pressure piston is driven and the modulator piston fixing mechanism becomes inoperable.
The modulator piston remains free. As a result, anti-lock control is performed as long as the control oil pressure remains in the accumulator, and after the control oil pressure completely disappears, braking is performed with the gain reduced by the 207 function, thereby preventing the wheels from slipping as much as possible. Ru.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of a modulator according to a first embodiment of the present invention, FIG. 2 is a sectional view of a modification of the first embodiment, and FIG. 3 is a sectional view of a modulator according to a second embodiment of the present invention. FIG. 4 and FIG. 5 are explanatory diagrams of the operation. 3...First cylinder, 4...Second cylinder, 5...
- Bulkhead, 6... Modulator piston, 7... First
Piston, 8... Input hydraulic chamber, 9... Control room, 11
... Spring, 12 ... Spring chamber, 13 ... Second
Piston, 14... Output hydraulic chamber, 16... First cut valve (cut valve), 22... Differential pressure piston, 23... Second cant valve (modulator piston fixed a structure), 33... ...Accumulator, 43...Piston rod (modulator piston fixing mechanism),

Claims (1)

[Scope of Claims] A first cylinder part (3) and a second cylinder part (4) formed coaxially with a partition wall (5) in between, and the partition wall (5).
A first piston (7) provided at both ends of a modulator piston (6) that slidably passes through the first piston (7) and slidingly engaged with the first cylinder part (3) and the second cylinder part (4), respectively; 7), and a control chamber (9) defined outside the first piston (7) and communicating with the accumulator (33).
), a spring chamber (12) defined on the outside of the second piston (13), communicating with the accumulator (33) and having a spring (11) contracted therein; an input hydraulic chamber (8) defined between the first piston (7) and communicating with the master cylinder (Cm), and an output defined between the partition wall (5) and the second piston (13) and communicating with the wheel brake. Hydraulic chamber (14) and the partition wall (5)
When the second piston (13) comes into contact with the valve during normal braking, the valve opens to communicate the input hydraulic chamber (8) and the output hydraulic chamber (14), and the second piston (13) opens when the anti-lock control is activated. An anti-lock brake modulator comprising a cut valve (16) that closes when the accumulator (13) separates and blocks communication between the input hydraulic chamber (8) and the output hydraulic chamber (14), a modulator piston fixing mechanism (23, 43) that fixes the modulator piston (6) so that the second piston (13) opens the cut valve when the pressure is reduced; and a master cylinder when the anti-lock control is activated. A differential pressure piston (22) is driven based on the differential pressure between the side hydraulic pressure (P_1) and the wheel brake side hydraulic pressure (P_2) and disables the modulator piston fixing mechanism (23, 43). A modulator for anti-lock brakes.