JPH0211470B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a load-responsive brake hydraulic pressure control device that changes the distribution of braking force between front and rear wheels according to the loaded load, and in particular applies a load according to the loaded load to a plunger that opens and closes a valve. This invention relates to improvements in load transmission mechanisms for

In general, proportioning valves apply the same braking force to the front and rear wheels when the braking force is low at the beginning of braking.
When the braking force exceeds a predetermined value, the braking force on the rear wheels is made smaller than that on the front wheels so that the front and rear wheels are simultaneously locked. By opening and closing the valve, the master cylinder pressure is reduced at a predetermined rate and transmitted to the rear wheel cylinder. And conventionally,
In order to give this proportioning valve characteristics according to the live load, a load corresponding to the live load is applied to the plunger to change the pressure at which the valve starts depressurizing operation, and as the load increases, the braking force of the rear wheels increases. A device is known in which the control start pressure is increased.

By the way, this type of device has conventionally converted changes in the distance between the body and the axle due to changes in the live load into changes in the biasing force of the sensor spring, thereby applying a load to the plunger according to the live load. However, even if the sensor spring should be damaged, it is necessary to ensure braking force for the rear wheels.

However, with conventional devices, when the sensor spring breaks, the plunger lifts and there is a risk that it will not be possible to secure the braking force for the rear wheels, or even if it is possible to secure the above braking force, the structure is extremely complicated and costs are high. There were problems such as.

The present invention has been made to solve these problems, and its purpose is to provide load-responsive braking that is simple and inexpensive in structure and that can secure braking force for the rear wheels in the event of sensor spring breakage. To provide a hydraulic control device.

To achieve the above object, the present invention is characterized by having a plunger that opens and closes a valve in response to master cylinder pressure, and by opening and closing the valve, the master cylinder pressure is reduced at a predetermined rate and transmitted to the rear wheel cylinder. A load-responsive braking hydraulic pressure control device comprising: a proportioning valve that applies a load to the plunger according to the load of the vehicle; and a load transmission mechanism that changes the depressurization start pressure of the valve; of,
The lever comprises a lever that is swingable about a desired position as a fulcrum, and a biasing means that is provided at the free end of the lever and applies a load to the plunger via the lever in accordance with the distance between the vehicle body and the axle of the vehicle, and the lever In this case, an arm section which is biased by a return spring in the opposite direction to the biasing means is branched and arranged in parallel, and a plunger that comes into contact with the lever is inserted through this arm section through a clearance. It is in.

The present invention will be described below based on illustrated embodiments.

In Fig. 1, 1 is the main body of the proportioning valve, which is attached to the vehicle body (not shown), and this main body 1 has an input hole 2 communicating with a master cylinder (not shown) and an input hole 2 communicating with a rear wheel cylinder (not shown). Output holes 3 are provided respectively. Further, the front wheel cylinder communicates directly with the master cylinder without going through the proportioning valve.

Inside the main body 1, there are a hole 5 into which the plunger 4 is slidably fitted, a valve chamber 6 communicating with the input hole 2, a through hole 7 communicating the valve chamber 6 with the output hole 3, and a valve chamber 6. A series of flow paths are formed from a passage 9 that communicates between the valve chamber 6 and the chamber 8, and a ball valve 10 that opens and closes the through hole 7 is disposed within the valve chamber 6. This ball valve 10 includes a ball 10a and a valve seat 10b.
and a compression spring 10c that presses and urges the ball 10a toward the valve seat 10b, and the ball valve 10 is opened and closed by the vertical movement of the plunger 4, as will be described later.

The plunger 4 includes a large diameter portion 4a that fits into the hole 5, a medium diameter portion 4b facing the interior of the chamber 8, and a small diameter portion 4c that protrudes to the outside of the main body 1 following the medium diameter portion 4b. The ball 10 is formed into a rod shape and loosely fits through the through hole 7 on the lower end surface of the large diameter portion 4a.
A protruding rod 11 is provided which comes into contact with a. The ball 10a is normally pressed by the rod 11 and is separated from the valve seat 10b. Also, the chamber 8
A packing cup 12, a retainer 13, and a ring retaining 14 are disposed on the outer periphery of the middle diameter portion 4b located at the upper part of the plunger 4 and the main body 1.
Ensures liquid tightness between the

On the other hand, as shown in FIG. 1, a lever 15 having a roughly U-shape is attached to an external position of the main body 1 above the plunger 4 so as to be swingable about a fulcrum 10. A sensor spring 17 that biases the lever 15 toward the main body 1 is connected to the free end, and the free end of the lower arm 15b of the lever 15 is biased by a return spring 19 disposed in a recess 18 formed in the main body 1. Main body 1
biased toward the side. The sensor spring 17 is configured such that its lower end changes its position between when the vehicle is empty (X) and when the vehicle is loaded (Y), as shown in FIG. It has come to be granted power according to the person. That is, the lower end of the sensor spring 17 is connected to the axle, and the distance between the vehicle body and the axle that changes depending on the load is determined by the sensor spring 17.
The force is converted into force and transmitted to the lever 15. Thus, this sensor spring 17 and the lever 15 constitute a load transmission mechanism that applies a force to the plunger 4 according to the loaded load. That is, the small diameter portion 4c of the plunger 4 protruding outside the main body 1 loosely fits through a hole 20 provided in the lower arm portion 15b of the lever 15, as shown in FIG. 1, and its upper end abuts on the upper arm portion 15a. As a result, a force corresponding to the live load is applied to the plunger 4. Further, the diameter D of the hole 20 is larger than the diameter d of the small diameter portion 4c, so that in the normal state, that is, the upper arm portion 1 of the lever 15 is operated by the sensor spring 17 with a force corresponding to the load.
5a is biased, the small diameter portion 4c is connected to the hole 2.
It is not in contact with the periphery of 0.

Thus, the biasing force of the sensor spring 17 changes depending on the load of the vehicle, and a force corresponding to the load acts on the plunger 4 via the lever 15. As a result, the pressure at which the ball valve 10 starts its decompression operation changes depending on the load.

Now, to simplify the explanation, the lever 15, sensor spring 17, and return spring 1 will be explained.
Assuming that there is no 9, the brake fluid pressure generated in the master cylinder (not shown) is directly introduced into the front wheel cylinder (not shown), and is also transmitted through the input hole 2 of the main body 1, the valve chamber 6, and the open ball. It is introduced into a rear wheel cylinder (not shown) through the valve 10, through hole 7 and output hole 3, respectively. That is, at the initial stage of braking, the input hole 2 and the output hole 3 are in a state of communication through a simple passage, and the brake fluid pressure in the master cylinder is directly supplied to the rear wheel cylinder, while the front wheel cylinder is directly supplied with the brake fluid pressure in the master cylinder. Since the brake fluid pressure in the master cylinder is directly supplied to both wheels, the same brake fluid pressure is introduced to the front and rear wheel wheel cylinders as shown by the straight line a in FIG. When the brake fluid pressure supplied to the rear wheel cylinder increases, this fluid pressure is simultaneously introduced into the chamber 8 via the passage 9 and acts on the step between the large diameter portion 4a and the middle diameter portion 4b of the plunger 4, on the other hand,
Since the same braking fluid pressure flowing through the through hole 7 from the input hole 2 acts on the lower end surface of the plunger 4, the plunger 4 moves upward due to the difference in the receiving area of the braking fluid pressure, as shown in FIG. At point A, the ball 10a seats on the valve seat 10b, stopping the increase in brake fluid pressure supplied to the rear wheel cylinder. When the brake fluid pressure further increases, the acting force that moves the plunger 4 upward does not increase because the ball 10a is seated, but the force between the large diameter part 4a and the middle diameter part 4b of the plunger 4 does not increase. Since the force acting on the stepped portion to lower the plunger 4 increases as the hydraulic pressure rises, the plunger 4 descends again, disengaging the ball 10a, and increasing the braking hydraulic pressure of the rear wheel cylinder. When the brake fluid pressure acting on the rear wheel cylinder, that is, the lower end surface of the plunger 4 increases, the plunger 4 moves upward again to seat the ball 10a, and therefore the brake fluid pressure decreases. Due to the rise, the plunger 4 moves up and down, and as shown by the straight line _b1 in Fig. 2, the braking fluid pressure in the rear wheel cylinder increases at a lower rate of increase than the fluid pressure increase on the master cylinder side, that is, on the front wheel cylinder side. It will be raised by

However, in reality, when the plunger 4 moves up and down, the upper end of the small diameter portion 4c of the plunger 4 comes into contact with the lever 15 and receives the force of the sensor spring 17. increases as the live load increases. That is, when the vehicle is empty, the biasing force of the sensor spring 17 is small, so the plunger 4 moves up and down at a low pressure as shown, for example, at point _B in FIG. However, during loading when the biasing force of the sensor spring 17 increases, the plunger 4 cannot move up and down unless greater braking pressure is generated.
The decompression operation start pressure increases as shown at point C,
Thereafter, the control shown by straight line _b3 is performed. However,
It becomes possible to control the brake fluid pressure in response to the load.

The case where the load transmission mechanism is operating normally has been explained above, but in the unlikely event that the sensor spring 17 is damaged, no force will be applied to the plunger 4 in accordance with the live load, and the plunger 4 will move up and down in a free state.
In this case, the initial pressure at which the plunger 4 opens and closes the ball valve 10 is an extremely low value (substantially zero) shown at point _A in FIG. Therefore, if the sensor spring 17 is damaged, sufficient braking force will not be provided to the rear wheels.

Therefore, in the present invention, when the sensor spring 17 is damaged, the lever 15 is rotated by the return spring 19, thereby locking the plunger 4.

That is, if the sensor spring 17 is damaged in the state shown in FIG.
Since the clockwise biasing force in the figure disappears and becomes a counterclockwise biasing force by the return spring 19, the lever 15 rotates counterclockwise as shown in FIG. 3. And the lever 15 is the lower arm part 15
The peripheral edge of the hole 20 b contacts the small diameter portion 4c of the plunger 4 and stops it in a slightly pulled up state, and thereafter the plunger 4 is held in that state by the biasing force of the return spring 19. Thus, the plunger 4 is locked with the input hole 2 and the output hole 2 communicating with each other. When the input and output holes 2 and 3 communicate, the braking fluid pressure from the master cylinder is directly introduced to the rear wheel cylinder, and as shown by the broken line a' in Figure 2, the same braking fluid pressure is introduced to the front and rear wheel cylinders. will be done. This makes it possible to secure sufficient braking force to the rear wheels.

Note that in the above embodiment, the lower arm portion 15 of the lever 15
Although the plunger 4 is locked by the hole 20 provided in the hole 20 in b, any structure may be used as long as the plunger 4 is locked by the rotation of the lever 15 due to the biasing force of the return spring 19. But that's fine.

FIG. 4 shows a second embodiment of the present invention,
Unlike the embodiments described above, the middle diameter portion 4 of the plunger 4
An annular spring seat 21 is fitted into the stepped portion 4d formed between the small diameter portion 4c and the small diameter portion 4c, and a return spring 1 is fitted between the spring seat 21 and the lever 15.
9 was inserted. According to this configuration, when the sensor spring 17 is damaged, the return spring 19 rotates the lever 15 counterclockwise and moves the plunger 4 downward, so that if the ball valve 10 is closed, Even if the sensor spring 17 is damaged, the plunger 4 moves downward during the locking operation to push down the ball 10a and open the valve 10.
As a result, the plunger 4 is locked with the input hole 2 and the output hole 3 communicating with each other, so that the brake fluid pressure of the master cylinder is directly transmitted to the wheel cylinder of the rear wheel, and sufficient braking force of the rear wheel is obtained. It will be done.

As described above, the present invention includes a swingable lever and a load transmission mechanism provided at the free end of the lever, which applies a load to the plunger according to the vehicle's carrying load to change the pressure at which the valve starts decompression. a biasing means for applying a load to the plunger via the lever according to the distance between the vehicle body and the axle of the vehicle, and the lever is biased by a return spring in a direction opposite to the biasing means; When the biasing means is damaged, the lever is rotated by the biasing force of the return spring, and the plunger is locked in a state where the braking fluid pressures of the front and rear wheels are equalized. Braking power can be obtained. Furthermore, since the plunger is locked by rotation of the lever, there is no need for a hydraulic mechanism, piston, or piping from the front wheel side, resulting in a compact and inexpensive device.

[Brief explanation of drawings]

Fig. 1 shows an embodiment of the present invention, a front view with main parts cut away, Fig. 2 is a graph schematically showing how the brake fluid pressure is controlled, and Fig. 3 shows the lever and plunger when the sensor spring is damaged. FIG. 4 shows another embodiment of the present invention, and is a front view with main parts cut away. 1: Main body, 2: Input hole, 3: Output hole, 4: Plunger, 10: Ball valve, 15: Lever, 1
6: fulcrum, 17: sensor spring, 19: return spring, 20: hole.

Claims (1)

[Claims] 1 A proportioning valve that has a plunger that opens and closes the valve in response to master cylinder pressure, and that reduces master cylinder pressure at a predetermined rate and transmits it to the rear wheel cylinder by opening and closing the valve, and a proportioning valve that reduces master cylinder pressure at a predetermined rate and transmits it to the rear wheel cylinder. A load-responsive braking hydraulic pressure control device comprising a load transmission mechanism that applies a load to the plunger and changes the depressurization operation start pressure of the valve, the load transmission mechanism comprising: a lever capable of swinging the load transmission mechanism about a predetermined position as a fulcrum; The lever includes a biasing means provided at the free end of the lever that applies a load to the plunger via the lever in accordance with the distance between the vehicle body and the axle, and the lever is provided with a return spring that is opposite to the biasing means. 1. A load-responsive braking hydraulic pressure control device, characterized in that arm portions that are biased in a direction are branched and arranged in parallel, and a plunger that contacts the lever is inserted through the arm portion with a clearance.