JPH036016B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a deceleration-responsive braking correction device used in an automobile brake system.

In particular, British Patent No. 913838 discloses a housing having a chamber therein into which an inlet orifice connected to a pressure source and an outlet orifice connected to a brake motor open, and between said chamber and said outlet orifice. A deceleration-responsive brake compensator is described, which includes a valve disposed in the chamber to control communication therebetween, and an inertial weight pivotally supported within the chamber to control the valve. .

In the correction device described in the above-mentioned patent, the closing element of the valve is supported by an inertial weight, and the relative position of the axis of rotation of the weight and the center of gravity is controlled by the weight, which It is set to move away from the closed position and on the other hand to approach said closed position by its own penetration during deceleration.

However, in this correction device, the deceleration at which the weight reaches the valve closing position is constant regardless of the load state of the vehicle.

The present invention is such that the operation of such a correction device is made to respond to the load of the vehicle, and in the above-mentioned type of brake correction device, the inertial weight is configured to adjust the inertial weight when the pressure in the room increases. It is characterized in that it has at least two elements, one of which can be slid relative to the other against an elastic device so as to change the position of the center of gravity of the weight.

According to the above configuration, the two elements forming the inertial weight can be moved relative to each other, so that the relative position between the axis of rotation and the center of gravity can be changed as a function of the brake pressure, and the weight can be reduced when the weight reaches the closing position of the valve. The velocity can also be varied as a function of this pressure.

Hereinafter, one embodiment of the present invention will be described in detail with reference to the accompanying drawings.

In the drawing, the motor vehicle brake system comprises a master cylinder 10 actuated in a known manner by a pedal 12 and a set of front brake actuators 14 connected directly to the master cylinder 10 by a conduit 16. It consists of a pair of rear brake actuators 18 connected to the master cylinder by conduits 20 and 22. A deceleration-sensitive brake compensator 24 according to the invention is arranged between a conduit 20 leading from the master cylinder 10 and a conduit 22 terminating in the rear brake actuator 18 .

The brake compensator 24 includes a housing 26 having a chamber 28 opening therein into which an inlet orifice 30 connected to the conduit 20 and an outlet orifice 32 connected to the conduit 22 open. An inertial weight 34 is pivotally mounted within the chamber 28 and has an axis of rotation indicated at P that is horizontal and perpendicular to the cross-section shown.

The inertial weight 34 is comprised of a first generally cylindrical element 36 and a second element comprising a stepped piston 38 slidably and coaxially fitted within the element. . The stepped piston 38 consists of a head 38a and a tail 38b with a small cross-sectional area.
8c is supported. The piston 38 delimits an air chamber 40 inside the cylindrical element 36, which is formed by a return interposed between a washer 44 fixed to the cylindrical element 36 and a counterweight 38c. Contains a spring 42.

A spring 42 presses the piston 38 against a shoulder 46 of the cylindrical element 36 to define a rest position of the piston.

In this rest position, the inertial mass 34 is located on a common axis of the cylindrical element 36 and the piston 38.
The center of gravity G of is located at a vertical distance a above the axis of rotation P and at a horizontal distance b behind this axis. Note that the moving direction of the vehicle is indicated by an arrow V.

Thus, the entire weight 34 is such that the extension 48 of the cylindrical element 36 rests against the bearing surface 50 of the housing 26.
It will be rotated counterclockwise in the figure by its own weight until it comes into contact with .

The cylindrical element 36 includes a bore 52 adjacent the piston head 38a which extends generally vertically and terminates in a valve seat 54. Valve plug 56
is secured to the housing 26 around the outlet orifice 32, opposite the valve seat 54.

Finally, the piston 38 has an axial passage 58 extending therethrough and opening into the chamber 28 at one end and into the bore 52 at the other end; A one-way flap 60 is provided to prevent fluid communication from 28 to hole 52.
The flap 60 has an axial rod 62 which projects into the bore 52 and abuts a beveled abutment member 64 secured to the housing 26. As shown, the abutment member 64 includes a central groove 66 that opens into the exit orifice 32.
Therefore, when the piston 38 is in the rest position, the rod 62 of the flap 60 is in contact with the flap spring 68.
Due to this action, the contact member 64 having an inclined surface is brought into contact with the contact member 64. As a result, a force is generated that acts to rotate the weight 34 counterclockwise for reasons described later.

The correction device 24 is configured so that the axis of the weight 34 is horizontal and oriented in the direction of arrow V in the figure, and the piston 38
The head 38a is mounted on the vehicle such that the head 38a is located at the front of the vehicle.

The brake compensation device described above operates as follows.

When the master cylinder 10 is actuated by depressing the pedal 12, pressure fluid is supplied to the front and rear brake actuators via conduits 16 and 20, respectively. Since the front brake actuator 14 is directly connected to the master cylinder 10, the pressure flowing into it is equal to the pressure created in the master cylinder.

On the other hand, the pressure flowing into the rear brake actuator 18 is modified by the compensation device 24 .

Initially, pressure fluid entering the inlet orifice 30 enters the bore 52 through the chamber 28 and into the groove 66.
It flows to the exit orifice 32 through the. Since the pressure at this time is low, the fluid force acting on the piston 38 is less than the force of the spring 42, and the piston remains in the rest position, with the flap in contact with the abutment member 64 having an inclined surface. A rod 62 at 60 holds the entire weight 34 in a rearwardly tilted position.

When the pressure exceeds a predetermined value, the fluid force acting on the piston 38 exceeds the force of the spring 42, causing the piston to move to the left in the figure. As a result of this backward movement of the piston, the flap 60 closes and the rod 62 separates from the ramped abutment member 64. In this state, the weight 34 can freely rotate clockwise. However, in order to rotate the weight, the torque generated by its inertial force must be greater than the counter torque generated by gravity. This condition occurs when the ratio of deceleration to gravity exceeds the ratio b:a of the horizontal and vertical distances between the center of gravity G and the axis of rotation P.

When the deceleration exceeds the above-mentioned value, the weight 34 rotates clockwise and the valve seat 54 contacts the valve plug 56, cutting off communication between the master cylinder 10 and the rear brake actuator 18. . From this condition, the pressure in the rear brake motor is reduced as a result of the static compression of fluid by the piston 38 to the tail 38a relative to the cross-sectional area of the piston head 38a.
Depending on the ratio of the cross-sectional area of the tail 38b to the cross-sectional area of the tail 38b, the pressure will rise more slowly than the pressure in the inlet orifice 30. That is, when the pressure in the inlet orifice 30 increases and the piston 38 approaches the rest position, the rod 62 contacts the abutment member 64 to open the flap 60, and as the pressure in the outlet orifice 32 increases, the piston moves backward again. and close the flap. In this way, the continuous opening and closing operation of the flap 60 and the flow control of fluid from the chamber 28 to the hole 52 and to the brake actuator 18 are performed, depending on the cross-sectional area of the head 38a relative to the cross-sectional area of the piston tail 38b. The pressure within the brake actuator increases more slowly than the pressure within chamber 28. Of course, the valve seat 54 is slightly inclined with respect to the axis of the cylindrical element 36 so that it comes into full contact with the valve plug 56 when the weight 34 is rotated.

It is clear that the deceleration rate at which the weight 34 rotates and the valves 54-56 close varies as a function of brake pressure. In fact, as the pressure increases,
The piston 38 moves to the left in the figure against the spring 42, and the center of gravity of the entire weight 34 also moves to the left, reaching, for example, point G'. In this state, the weight 3
The deceleration at which the rotation of 4 occurs is such that the ratio of deceleration to gravity is greater than B:a, where B is the horizontal distance between the new center of gravity G' and the axis of rotation P. There must be.

It is therefore clear that the brake compensator according to the invention can be configured to react to the vehicle load in a very simple manner since the deceleration of the vehicle is directly dependent on its load. .

When the pressure is released, the exit orifice 3
A backward movement of the piston 38 against the spring 42 occurs until the pressures in the chamber 28 and 2 are equal. Thereafter, the weight 34 will rotate back under the action of gravity and abut the bearing surface 50 of the housing 26, opening the valves 54-56.

That is, when the pressure within hole 52 equalizes the pressure within chamber 28, flap 60 opens to allow fluid to freely return from brake actuator 18 to chamber 28. Thereafter, the piston 38 connects the chamber 28 and the hole 5.
gradually returns as a result of the decrease in pressure within 2. During this return movement of the piston, the return flow of fluid from the brake actuator 18 forms a jet stream emerging from the groove 66, thus creating a dynamic fluid force that acts to rotate the weight 34 in a counterclockwise direction. will occur.

When the piston 38 reaches the rest position, the rod 6
2 comes into contact with an abutting member 64 having an inclined surface. As a result of this, first, flap 60 can open to allow fluid to flow from chamber 28 to hole 52;
Second, the entire weight 34 will again abut the bearing surface 50 to ensure that the valve seat 54 is spaced from the valve plug 56.

This may occur if there is a slight leakage between the valves 54-56 and the brake actuator 18, even after the pressure has been completely released.
56 is held in the closed position.

[Brief explanation of the drawing]

The drawing is a schematic diagram of an automobile brake system showing a deceleration-responsive brake correction device according to the present invention in cross section. 10...Master cylinder, 14...Front wheel brake actuator, 18...Rear wheel brake actuator, 24...Brake compensation device, 26...Housing, 28...Chamber, 30...Inlet orifice, 32... ...Exit orifice, 34...Inertia weight, 36...Cylindrical element, 38...Stepped piston, 38a...Head, 38b...Tail, 42
... Return spring, 52 ... Hole, 54 ... Valve seat, 56 ... Valve plug, 58 ... Passage, 60 ...
One-way flap, 62...rod, 64...abutting member, 68...flap spring.

Claims (1)

[Claims] 1. Inlet orifice 30 connected to pressure source 10
and an outlet orifice 32 connected to the brake actuator 18; valves 54-56 for controlling; and an inertial weight 34 pivotally mounted within said chamber 28 for controlling said valves 54-56.
In the deceleration-responsive braking correction device, the inertial weight 34 is connected to an elastic device 42 so as to change the position of the center of gravity G of the inertial weight 34 when the pressure in the chamber 28 increases. at least two elements 3, one 38 slidable relative to the other 36;
6, 38. A deceleration-responsive braking correction device comprising: 2. Said one element is slidably fitted into said other element 36 and is pulled into its rest position by said elastic device 42 at the shoulder 46 of the other element 36.
The head 38a and the tail 38 are pushed in the direction of the head 38a and are exposed to the pressure flowing into the chamber 28.
2. The brake compensation device according to claim 1, characterized in that it comprises a stepped piston 38 having a diameter of 1.b. 3. The other element comprises a cylindrical element 36 that coaxially accommodates the stepped piston 38 and whose axis is oriented in the direction of movement of the vehicle;
The cylindrical element 36 and the stepped piston 38 are configured such that the center of gravity G of the inertial mass 34 is located above and behind the rotational axis P of the inertial mass 34 with respect to the direction of movement of the vehicle. A braking correction device according to claim 2 characterized by: 4. The valve comprises a valve seat 54 supported by the inertial weight 34 and a valve plug 56 supported by the housing 26 around the outlet orifice 32 opposite the valve seat. A brake correction device according to any one of claims 1 to 3. 5 The valve seat 54 is formed in the cylindrical element 36, and the head 38a of the stepped piston 38 is
5. The brake compensation device according to claim 4, wherein the valve seat 54 is penetrated and exposed to a hole 52 provided in the cylindrical element 36. 6 The stepped piston 38 has an axial passage 58 therethrough communicating between the chamber 28 and the bore 52, with fluid communication from the chamber 28 to the bore 52 within the passage 58. 6. The braking correction device according to claim 5, further comprising a one-way flap 60 for preventing the braking. 7. The flap 60 has a rod 62 projecting into the hole 52, which rod 62, in the rest position of the stepped piston, abuts an abutment member 64 provided in the housing 26 that projects into the hole. 7. The brake compensation device according to claim 6, wherein the flap 60 is opened when the brake is in contact with the brake. 8 The abutting member 64 has an inclined surface, and the rod 62 is pressed against the inclined surface by a flap spring 68 to apply a force in the direction of separating the valve seat 54 from the valve plug 56. The braking correction device according to claim 7, characterized in that the braking correction device acts on an inertial weight 34.