JPS6312829B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a brake fluid pressure generating device used in a vehicle brake system, which includes a master cylinder and a booster equipped with a power piston that operates in response to operation of a brake pedal.

In recent years, there has been a strong demand for various devices for vehicles to be smaller and lighter in order to improve fuel efficiency and the like. When reducing the size and weight of the brake fluid pressure generator described above, it is effective to reduce the cylinder diameter of the master cylinder and the power piston diameter of the booster. If the diameter is reduced, the operation stroke of the brake pedal becomes excessive, which impairs brake performance.

An object of the present invention is to solve this problem without increasing the operating force (depression force) of the brake pedal, and one embodiment thereof will be described below with reference to the drawings.

The figure shows a brake fluid pressure generating device employed in an automobile brake system, and this device consists of a master cylinder 100 and a vacuum booster 200 integrated therewith. A stepped cylinder 111 coaxial with the power piston 210 of the vacuum booster 200 is formed in the cylinder body 110 of the master cylinder 100, and a primary piston 120 and a secondary piston 130 are attached to the small diameter portion 112 of the cylinder 111. A cylindrical piston 140 is fitted into the large diameter portion 113 of the cylinder 111 so as to be slidable in the axial direction.

The primary piston 120 is biased to the right by a return spring 121 and held at the return position shown in the figure by a stopper bolt 122. A liquid chamber 190 is formed on the left side by the secondary piston 130, and a cylindrical piston is formed on the right side. 14
0 forms a liquid chamber 191. Further, the primary piston 120 is provided with a communication hole 129, and the piston cup 123 is connected to the liquid chamber 191 due to the pressure difference between the liquid chamber 191 and the liquid chamber 190.
It is mounted to allow liquid flow from the liquid chamber 190 to the liquid chamber 190. The fluid chamber 190 is a braking fluid pressure generation chamber, and when the primary piston 120 is in the position shown, a port 114 connected to a wheel cylinder (not shown) and a reservoir 150 are connected to each other.
(a valve seat 161 of a check valve 160 described later)
A compensation hole 115 (which communicates through a compensation hole 169 provided in the hole) is open. The liquid chamber 191 has a communication hole 1.
16 is open, and this communication hole 116 communicates with the reservoir 150 via a check valve 160 that is integrally provided with a relief valve 165. Check valve 160
The valve seat 161 is fixed in the reservoir connection port of the cylinder body 110, and the movable support 16 is located below the valve seat 161 and supports the valve body 162.
3. Consisting of a spring 164 that urges this support 163 upward and a relief valve 165 built into the support 163, the relief valve 165 allows liquid to flow out from the reservoir 150 and prevents liquid from flowing back into the reservoir 150. suppressed by In addition, relief valve 1
The valve opening pressure of 65 is set to a relatively low predetermined value (the pressure required to make the shoe clearance zero).

The secondary piston 130 is biased to the right by a return spring 131 and is biased to the left by a return spring 121 having a larger resiliency than the return spring 131. The primary piston 120 is held in the return position by contact with the primary piston 120 (which is attached to the primary piston 120 and is prevented from coming off by a retainer 124 fixed to the primary piston 120). This secondary piston 130 is connected to the cylinder body 1
10 form liquid chambers 192 and 193, and the liquid chamber 192 has a port 117 connected to a wheel cylinder of another system (not shown) and a compensation hole 118 communicating with the reservoir 150. A communication hole 119 that communicates with the reservoir 150 is opened in the chamber 193 . Further, the secondary piston 130 is provided with a communication hole 139 and piston cups 133, 134 are attached thereto, and the left piston cup 133 is connected to the liquid chamber 193.
The liquid chamber 193 is installed to allow liquid to flow from the liquid chamber 193 to the liquid chamber 192 due to the pressure difference between the liquid chamber 193 and the liquid chamber 192.

The cylindrical piston 140 is connected to the return spring 1
41 to the right, and is held at the return position shown in the figure by a clip 142, and its inner hole 1
A rod portion 125 of the primary piston 120 is accommodated within the rod portion 43 so as to be slidable in the axial direction. A piston cup 144 is attached to the outer periphery of the cylindrical piston 140, and a piston cup 126 is attached to the outer periphery of the rod portion 125, so that the liquid chamber 191 is sealed from the outside. Further, an annular plate 145 is screwed into the right inner hole of the cylindrical piston 140.

On the other hand, in the vacuum booster 200, the power piston 210 is a diaphragm piston 220.
and a valve piston 230. The diaphragm piston 220 is connected to the housing 240
A diaphragm 22 whose outer peripheral edge is airtightly fixed to the
1 and a sleeve 222 hermetically fixed to the inner peripheral edge of the diaphragm 221, and is urged rightward by a return spring 219.
This diaphragm piston 220 has a flange 2 having a communication hole 223a in its sleeve 222.
It is constantly engaged with the plate 145 of the cylindrical piston 140 via a sleeve 224 provided with 23.
The valve piston 230 includes a sleeve 231 that is axially slidably and airtightly assembled into the sleeve 222 of the diaphragm piston 210, and a main body 2 that is airtightly and integrally assembled to the sleeve 231.
32, and the axial movement of the sleeve 231 is restricted by a projecting wall 225 provided integrally with the sleeve 222 of the diaphragm piston 220 and a clip 226 fixed to the sleeve 222, so that the diaphragm piston 210 It is assembled so that it can be relatively moved by a predetermined amount in the axial direction.
The main body 232 has an inner hole 232a and a communication hole 232.
b, 232c, and the right end portion extends outside the housing 240 via a seal member 249. This main body 232 has an operating rod 233 connected to a brake pedal (not shown), a valve plunger 234, a poppet 235, and an air cleaner 23 in the right side of the inner hole 232a.
It accommodates 6. Further, the main body 232 has an inner hole 23
A reaction rubber disk 237 and a plug 238 (slidable relative to the main body 232) and a push rod 239 (slidable in an airtight manner relative to the sleeve 224) are assembled to the left end of 2a.
The primary piston 120 of the master cylinder 100 is removably engaged with the primary piston 120 of the master cylinder 100 via. Note that a stopper 211 that comes into contact with the inner surface of the housing 240 is attached to the main body 232 . The operating rod 233 and valve plunger 2 mentioned above
34, poppet 235 and air cleaner 236
The configuration is the same as that of a conventionally known vacuum booster, and the operating
3. Due to the cooperative action of the valve plunger 234, poppet 235, and main body 232, the housing 2
A right chamber 241 formed by the power piston 210 in the left chamber 2 is connected to a negative pressure source at all times.
42 or the atmosphere, which is likely to be easily understood, so a description thereof will be omitted.

In this embodiment configured as described above, the vacuum booster 200 is activated by depressing the brake pedal.
When the operating rod 233 is moved to the left, the valve plunger 234, poppet 235, and main body 232 of the valve piston 230 work together to allow air to flow into the right chamber 241, causing the power piston 210 to move between the two chambers 241 and 242. The pressure moves the primary piston 120 of the master cylinder 100 to the left against the return spring 219, and the secondary piston 130 is also pushed through the liquid in the liquid chamber 190, causing the primary piston 120 to move to the left. Piston cup 123 due to left movement
After closing the communication between the liquid chamber 190 and the compensation hole 123, the liquid pressure in the liquid chamber 190 increases, and the liquid in the liquid chamber 190 is discharged from the port 114 toward one system of wheel cylinders. After the piston cup 133 closes the communication between the liquid chamber 192 and the compensation hole 118 due to leftward movement, the liquid pressure in the liquid chamber 192 increases, and the liquid in the liquid chamber 192 is discharged from the port 117 toward the wheel cylinder of another system. , braking force can be obtained.

By the way, at the beginning of the leftward movement of the power piston 210 described above, the diaphragm piston 220 moves to the left before the valve piston 230, and this is transmitted to the cylindrical piston 140 via the sleeve 224 and the plate 145, so that the cylindrical piston 140 moves to the left. By moving to the left, the liquid pressure in the liquid chamber 191 is increased to a level (below a predetermined value) that does not open the relief valve 165, and the liquid in the liquid chamber 191 mainly passes through the communication hole 129 and the outer periphery of the piston cup 123. At the same time, the liquid in the liquid chamber 190 flows into the port 114.
The fuel is discharged from the air to one system of wheel cylinders, and the one system of wheel cylinders is idled (operation until the shoe clearance becomes zero). At this time, the secondary piston 130 is moved to the left by the liquid flowing into the liquid chamber 190,
The liquid in the liquid chamber 192 is discharged from the port 117 toward the wheel cylinders of other systems, thereby idling the wheel cylinders of the other systems. During this time, the valve piston 230 was also moving slightly to the left.
The left movement of the valve piston 230 causes the primary piston 12 to move through the reaction rubber disk 237, plug 238, and push rod 239.
0 is pushed to the left, and by the time the shoe clearance becomes zero, the hydraulic pressure in the liquid chamber 190 is
1, the pressure in the liquid chamber 191 becomes higher than a predetermined value, and the relief valve 165 opens. After that, the liquid in the liquid chamber 191 mainly flows through the communication hole 116.
By flowing into the reservoir 150 through the relief valve 165, the cylindrical piston 140 can be moved to the left. Thus, the sleeve 222 of the diaphragm piston 220 is connected to the valve piston 230.
When the pistons 220 and 230 are engaged with the sleeve 231 and become integral, almost all of the leftward pressing force that acts on both pistons 220 and 230 acts on the primary piston 120, and the liquid pressure in the liquid chamber 190 becomes high, The liquid pressure in the liquid chamber 192 is set to high pressure, and a large braking force is obtained. At this time, the liquid pressure in the liquid chamber 190 is transmitted through the primary piston 120, the push rod 239, the plug 238, and the reaction rubber disk 237, and from the reaction rubber disk 237 to the main body 2 of the valve piston 230.
32 and the valve plunger 234, and is transmitted from the valve plunger 234 to the operating rod 233 and the brake pedal to provide a reaction force to the driver.

Furthermore, when the brake pedal is released, the primary piston 120 and the secondary piston 1
30, cylindrical piston 140 and power piston 2
10 returns to the illustrated return position by the action of each return spring. At this time of return, liquid chamber 1
When the pressure in the liquid chamber 190 tends to be negative, the liquid in the liquid chamber 191 flows into the liquid chamber 190 through the communication hole 129 and the outer circumference of the piston cup 123, and when the pressure in the liquid chamber 191 tends to be negative, the liquid in the reservoir 150 flows into the liquid chamber 190. The liquid in the liquid chamber 193 flows into the liquid chamber 191 through the check valve 160 and the communication hole 116, and when the liquid chamber 192 tends to have a negative pressure, the liquid in the liquid chamber 193 flows through the communication hole 139 and the outer periphery of the piston cup 133. The liquid flows through the liquid chamber 192 and releases the brake smoothly. Thus, each piston 12 of master cylinder 100
0, 130, and 140 return to the illustrated return position, the liquid chamber 190 communicates with the reservoir 150 through the compensation hole 115 provided in the cylinder body 110 and the compensation hole 169 provided in the valve seat 161 of the check valve 160, Further, the liquid chamber 191 communicates with the reservoir 150 through the communication hole 116 and the compensation hole 169 provided in the cylinder body 110, and the liquid chamber 192 communicates with the reservoir 150 through the compensation hole 118 provided in the cylinder body 110. , expansion and contraction of the fluid in the brake system will not cause abnormal pressure in the fluid chambers 190, 192, and no malfunction of the brake will occur.

As can be understood from the above description, in this embodiment, the diaphragm piston 220 operates before the valve piston 230 at the initial stage of operation of the power piston 210, which operates in response to the depression of the brake pedal. shaped piston 140
is pushed through the sleeve 224, and the liquid chamber 191
The liquid inside flows into the liquid chamber 190, and the liquid in the liquid chamber 190,1
Since the liquid in 92 is discharged toward the respective wheel cylinders, it is assumed that the master cylinder 100
The diameter of the cylinder 111 (especially the small diameter part 112
The diameter of the power piston 210 in the vacuum booster 200 is reduced to reduce the size and weight of the brake pedal, and to reduce the reaction force of the brake pedal.
Even if the diameter of the primary piston 120 is reduced to reduce the size and weight, the required (large amount) of fluid can be discharged toward the wheel cylinder without significantly moving the primary piston 120, which moves substantially integrally with the brake pedal. brake performance can be improved. Furthermore, in this example,
The cylindrical piston 140 is a vacuum booster 200
Since the brake pedal is pushed by the diaphragm piston 220 of the power piston 210 in the brake pedal, it is possible to improve the operability without increasing the operating force (depression force) of the brake pedal.

In the above embodiment, the tandem master cylinder 100 and vacuum booster 200 are
The brake fluid pressure generating device according to the present invention is constructed by using a single master cylinder and a vacuum booster 20.
Of course, it can be constructed by a master cylinder and various types of boosters.

[Brief explanation of the drawing]

The figure is a partially vertical side view showing one embodiment of the present invention. Explanation of codes, 100...Master cylinder, 1
DESCRIPTION OF SYMBOLS 10... Cylinder body, 111... Stepped cylinder, 112... Small diameter part of cylinder, 113... Large diameter part of cylinder, 114... Port, 115...
Compensation hole, 116... Communication hole, 120... Primary piston (operating piston), 123... Piston cup, 125... Rod portion, 140... Cylindrical piston, 150... Reservoir, 160... Check valve, 190...Liquid chamber (first liquid chamber), 191...Liquid chamber (second liquid chamber), 200...Vacuum booster,
210...Power piston, 220...Diaphragm piston, 224...Sleeve (cylindrical connection body), 230...Valve piston.

Claims (1)

[Claims] 1 Consists of a master cylinder and a booster equipped with a power piston that operates in response to the operation of the brake pedal.The cylinder body of the master cylinder is formed with a stepped cylinder, and the operating piston is located in the small diameter part of this cylinder in the axial direction. A first liquid chamber is formed on the small diameter side of the cylinder in which a port connected to the wheel cylinder is always open and a compensation hole communicating with the reservoir is opened when the working piston returns. A second liquid chamber is formed on the large-diameter side of the cylinder and has a communication hole that communicates with the reservoir via a check valve and a relief valve that suppress liquid backflow to the reservoir, and a second liquid chamber is formed on the large diameter side of the cylinder. is equipped with a piston cup that allows fluid to flow from the second fluid chamber to the first fluid chamber due to the pressure difference between the two fluid chambers, and the rod portion of the operating piston is attached to the large diameter portion of the cylinder in the axial direction. a diaphragm piston, into which a cylindrical piston is slidably fitted in the axial direction, and a diaphragm piston in which the power piston of the booster engages with the cylindrical piston via a cylindrical connection body; The valve piston is assembled into a diaphragm piston so as to be relatively movable by a predetermined amount in the axial direction, is operatively connected to the brake pedal, and is operatively engaged with the actuating piston through the cylindrical connecting body; When the power piston is actuated by operating a brake pedal, the diaphragm piston operates before the valve piston in the initial stage of operation, and the cylindrical piston is pushed by a predetermined amount via the cylindrical connection body, Thereafter, the diaphragm piston engages with the valve piston and operates integrally, and this is transmitted to the actuating piston to push the actuating piston, so that braking fluid pressure is generated in the first fluid chamber. Braking fluid pressure generator.