JPS5932345B2 - Adjustable load brake hydraulic control valve - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a variable load brake fluid pressure control valve that adjusts the hydraulic pressure of brake fluid supplied to a brake cylinder according to the loaded weight of a vehicle.

In a conventional variable load brake fluid pressure control valve, for example, a piston is slidably provided in the control valve body to cut off the supply of brake fluid to the brake cylinder by moving in response to fluid pressure, and the end of the piston is A link having a spring force that biases the piston in a direction opposite to the hydraulic pressure is brought into direct contact with the piston, and the spring of the link is There is a link type control valve that changes the force and adjusts the cut pressure of the hydraulic pressure supplied to the brake cylinder.

However, in the link type variable load brake fluid pressure control valve mentioned above, due to the use of a link, the installation position of the control valve is limited to near the rear axle of the vehicle, and the cut pressure is zero when the link is broken. Therefore, in preparation for such a case, it is necessary to separately provide a guarantee mechanism for supplying the minimum hydraulic pressure to the brake cylinder, resulting in a problem that the structure becomes complicated.

Furthermore, when used for a long period of time, the links tend to fatigue, resulting in changes in their spring characteristics and rusting.Therefore, when the links are replaced, there is a problem in that it is extremely difficult to adjust the cutting pressure when reassembling the links. .

The present invention solves the above-mentioned problems by providing a valve body of a valve mechanism that cuts off the supply of brake fluid to the brake cylinder due to vertical displacement between the sprung upper side and the unsprung lower side of the vehicle according to the loaded weight. It is characterized in that the cut pressure of the variable load brake fluid pressure control valve is controlled by converting it into a separation distance between the valve seat and the valve seat.

Embodiments of the present invention will be described below with reference to the drawings.

1 and 2, 1 is the main body of the hydraulic control valve, and the main body 1 has a cylinder 2, a cylinder 3 with a larger diameter than the cylinder 2, and holes 4 and 5 in a straight line from the left in the figure. Arranged on a line and communicated with each other.

The left end opening of the cylinder 2 is covered with a spring case 6 which is screwed onto the main body 1 and has a hollow part on the same line as the cylinder 2, and the hole 5 has a cylinder with a smaller diameter than the left side in the figure. A plug I formed by connecting a and a large diameter cylinder γb is screwed.

This cylinder? a pγb is also on the same straight line as cylinder 2.

8 is the brake fluid inlet, 9 is the brake fluid outlet,
A master cylinder (not shown) is connected to the inlet 8, and a brake cylinder (not shown) for the rear wheel of the vehicle is connected to the outlet 9.

The inlet 8 communicates with a primary hydraulic pressure chamber 10 formed within the cylinder 3, and the outlet 9 communicates with a secondary hydraulic chamber 11 formed within the hole 4.

12 is a stepped piston having a small diameter part 12a and a large diameter part 12b, and the stepped piston 12 is inserted into the cylinder such that the small diameter part 12a slides inside the cylinder 2 and the large diameter part 12b slides inside the cylinder 3. Insert into 2 and 3.

A ring 13 is attached to the left side of this stepped piston 12,
A spring 14 is housed between the ring 13 and the spring case 6 so as to have a free length or a compressed state, and the movement of the stepped piston 12 to the left in the figure is caused by the compression. Controlled by elastic force.

Since the ring 13 comes into contact with the left end of the main body 1, the stepped piston 12 is not subjected to the elastic force of the spring 14, and its movement to the right in the figure is restricted.

A liquid passage 15 is formed in the stepped piston 12 to communicate the primary hydraulic chamber 10 and the secondary hydraulic chamber 11, that is, to communicate the inlet 8 and the outlet 9.

A ring-shaped valve seat 16, which constitutes a part of the valve mechanism for opening and closing the liquid passage 15, is provided at the right end of the stepped piston 12. A spherical valve body 17 seated on a valve seat 16 is housed.

Further, a valve spring 18 is housed in the liquid passage 15, and the valve spring 18 always urges the valve body 11 toward the valve seat 16.

The plug 7 is provided with a plunger 19 having a small diameter portion 19a and a large diameter portion 19b.
and the large-diameter cylinder 7b, respectively, and are slidably fitted therein.

A dust cover 20 has a hemispherical abutting end 19c formed at the right end of the plunger 19 and protrudes out of the main body 1, with one end fixed to the protruding part of the plunger 19 and the other end fixed to the main body 1. This prevents dust and the like from entering the main body 1.

Further, a small-diameter valve stem 19a is formed at the left end of the plunger 19, and the valve stem 19d passes through the ring-shaped valve seat 16 and extends to the left in the figure. The valve body 17 and the valve seat 16 are separated from each other.

Therefore, the plunger 19 is given a slight biasing force to the right in the drawing by the valve spring 18, and the distance that the valve body 11 is separated from the valve seat 16 is adjusted by the left and right movement of the plunger 19 in the drawing.

On the other hand, a bracket 22 is attached to the side of the main body 1 with bolts 21, 21.

A cam guide groove 23 extending in a direction perpendicular to the axial direction of the plunger 19 (in the vertical direction in the figure) is formed in a bent manner on the right side of the bracket 22. A plate-shaped cam 24 is inserted if possible.

The cam 24 has its right end sliding surface 24a aligned with the guide groove 23.
The guide surface 23a of the plunger 19 is brought into contact with the guide surface 23a, and the cam ring distance curve 24b formed at the left end thereof is brought into contact with the contact end 19c of the plunger 19.

In order to regulate the vertical stroke of the cam 24, a regulation groove 24c extending vertically is formed on the plate surface of the cam 24, and a pin-shaped stopper 25 is inserted into the regulation groove 24c and engaged with the cam guide groove 23. Stop.

Therefore, the plunger 19 moves as the cam 24 moves up and down.
A forward and backward movement in the left-right direction corresponding to the cam ring distance curve 24b is given, but in the embodiment, the plunger 19 is moved more leftward in the figure as the cam 24 moves upward, i.e. The cam ring distance curve 24b is formed in a straight line so that the distance between the valve seat 16 and the valve body 17 is large.

Further, the minimum width h of the cam 24 (distance between the cam guide surface 23a and the abutting end 19c) is such that the plunger 19 is connected to the valve seat 19 when the stepped piston 12 is located at the rightmost position, that is, in the illustrated state. and the valve body 17 by a distance that guarantees the minimum guaranteed hydraulic pressure.

A wire stop 26 is bent below the bracket 22, and one end 2γA of the pipe-shaped outer wire 2γ is fixed to the wire stop 26 with a nut 28, and one end 29a of the inner wire 29 inserted into the outer wire 27 is fixed to the wire stop 26. is connected to the cam 24.

A return spring 30 is inserted between the cam 24 and the wire stopper 26, and the return spring 30 always urges the cam 24 upward.

In order to install the variable load brake fluid pressure control valve according to the present invention configured as described above to a vehicle, for example, as shown in FIG.
at an appropriate location on the frame 31, which is a member on the sprung side,
Further, the other ends 29b of the inner wires 29 are attached to appropriate locations on the differential case 32, which is an unsprung member.

Conversely, the control valve body 1 and the other end 27b of the outer wire 27 may be attached to the differential case 32, and the other end 29b of the inner wire 29 may be attached to the frame 31.

Of course, the attachment site is not limited to the frame 31 or the differential case 32.

The operation of the variable load brake fluid pressure control valve according to the present invention will be explained below.

First, we will explain the case when the vehicle is empty. In this case, since the distance between the frame 31 and the differential case 32 is large, the inner wire 29 is sufficiently pulled by the differential case 32, so that the cam 24
is the position that has moved downward in the figure, so plunger 19
is biased to the right by the valve spring 18, causing the valve seat 16 and the valve body 1 to
The distance from γ is small.

At this time, when the driver steps on the brake, the pressure oil from the master cylinder flows through the inlet 8, the primary hydraulic pressure chamber 10, and the fluid passage 15.
, through the secondary hydraulic pressure chamber 11 and the outflow port 9 to reach the brake cylinder, but the stepped piston 12 moves to the left in the figure due to the hydraulic pressure applied to the pressure receiving area of the small diameter portion 12a of the stepped piston 12. This compresses the spring 14, and the stepped piston 12 stops at a position that balances the force exerted by the compression.

When the brake pedal pressure is weak and the master cylinder hydraulic pressure is below point a in Figure 4, the valve seat 16 and the valve body 17 are separated, so the master cylinder hydraulic pressure and the brake cylinder hydraulic pressure are different. become equal.

When the brake is pressed even harder to raise the master cylinder hydraulic pressure to a value above point a, the stepped piston 12 moves further to the left, and the valve body 11 finally seats on the valve seat 16, causing the brake cylinder of the rear wheel to Cut off the hydraulic pressure supply to.

Then, the large diameter portion 12b side of the stepped piston 12 also has a pressure receiving area, and the hydraulic pressure applied to the difference causes the stepped piston 12 to
A force is applied to the right side in the figure, and as the hydraulic pressure in the primary hydraulic chamber 10 increases, the stepped piston 12 moves to the right, and the valve body 1
7 and the valve seat 16 are separated.

Then, the pressure receiving area becomes only the small diameter portion 12a, and the valve body 17 is seated on the valve seat 16 due to the increase in hydraulic pressure as described above.

Thereafter, the valve body 17 and the valve seat 16 are repeatedly separated and seated, and an idle operation characteristic line sloping upward to the right as shown in FIG. 4A is obtained.

Therefore, the brake cylinder can be supplied with pressurized liquid that increases at a rate of increase in hydraulic pressure that is smaller than the hydraulic pressure corresponding to the hydraulic pressure of the master cylinder.

Next, the case when the vehicle is loaded will be explained. In this case, the distance between the frame 31 and the differential case 32 becomes smaller, so the inner wire 29 is bent more than when the vehicle is empty, and the return spring 30 causes the cam 24 to
is moved upward, and therefore the plunger 19 moves to the left in the figure, and the distance between the valve seat 16 and the valve body 1γ increases.

Therefore, when the valve body 17 is seated on the valve seat 16, the master cylinder hydraulic pressure (indicated by the dot in Figure 4) increases, and as shown in Figure 4, even if the master cylinder hydraulic pressure is the same, the This makes it possible to obtain an operating characteristic line when the vehicle is loaded, in which the rear wheel brake cylinder hydraulic pressure is greater than when the vehicle is empty.

Note that, unlike the embodiment, the large diameter side 12b of the piston 12
By making the diameter the same as the small diameter side 12a, the operating characteristic line shown in FIG. 5 can be obtained.

Here, the plunger 1 is operated by the hydraulic pressure in the secondary hydraulic pressure chamber 11.
9 to the right in the figure is supported by the cam guide surface 23a, the cam 24, which moves in the direction perpendicular to the axis of the plunger 19, is hardly affected by the pressing force and moves the inner wire 29. It can move up and down smoothly by following the displacement.

Further, in order to finely adjust the cutting pressure according to the loaded weight, the cam 24 may be slightly displaced by turning the nut 28 and changing the effective tensile length of the inner wire 29.

Furthermore, to explain the case where the inner wire 29 is cut, in this case, regardless of the loaded weight, the cam 24 moves upward by the return spring 30 until it is stopped by the stopper 25, and the valve seat 16 and the valve body 18 This means that they are separated by the maximum amount.

Therefore, even if the inner wire 29 is cut, the cutting pressure can be prevented from becoming zero, and a rear-end collision of the vehicle due to the ineffectiveness of the brake can be prevented.

Note that if the minimum width of the cam 24 is determined to ensure the minimum hydraulic pressure as described above, even if the return spring 30 is damaged, the cutting pressure can be prevented from becoming zero.

Next, a second embodiment of the present invention will be described based on FIGS. 6 to 8.

Note that the same components as in the previous embodiment are given the same reference numerals, and the differences from the previous embodiment will be explained below.

In this embodiment, the plug T includes a large diameter cylinder 7b, a small diameter cylinder 7a, and an even larger diameter hole 7''.
C is provided.

A female thread γd is formed in the large diameter hole 7c.

The plunger 19 is attached to the plug T at its small diameter portion 19a.
is slidably inserted into the small-diameter cylinder 7a, and its large-diameter portion 19b is tightly and slidably inserted into the small-diameter cylinder γb.

Furthermore, movement of the plunger 19 to the right in the figure is restricted by a stepped portion 7e formed by a small-diameter cylinder γa and a large-diameter cylinder 7b.

An adjustment screw 41 is screwed into the female thread 7d of the plug I, and the inner end of the adjustment screw 41 faces the contact end 19c of the plunger 19, so that a slight gap is formed between the two wheels. ing.

A lever 43 is integrally fixed to the adjustment screw 41 with a bolt 42.

A hole 43a is formed in the lever 43 in the middle thereof, and a small hole 1a is also formed in the wall of the main body 1.

A coil spring 44 is attached to the outer periphery of the plug 7 with a twisting force, with both ends supported by the hole 43a and the small hole 1a.

This torsional force acts on the lever 43 in FIG. 7 so as to rotate the lever 43 counterclockwise.

Furthermore, the adjustment screw 41 and the female thread γd are as follows:
When the adjustment screw 41 is rotated counterclockwise in FIG. 2, the screw 41 is threaded so as to move forward to the left in FIG. 1.

One end of a wire 45 is attached to the tip of the lever 43.

Here, the state in which the variable load brake control valve according to the second embodiment of the present invention is attached to a vehicle will be explained with reference to FIG. The other end is fixed to the rear axle 47.

When the vehicle is empty, the distance between the frame 46 and the rear axle 47 is large, so that the wire 45 pulls the lever 43 against the torsional force of the coil spring 44, as shown in FIG.

Furthermore, when the vehicle is loaded, the distance between the frame 46 and the rear axle 47 becomes narrower and the wire 45 becomes loose, so the lever 43 receives the torsional force of the coil spring 44 and rotates counterclockwise, causing the adjustment screw to rotate. 41 is displaced to the left in FIG. further apart.

The operation of the control valve when the vehicle is empty and when it is loaded is the same as in the previous embodiment.

By the way, when the wire 45 is cut, the adjustment screw 41 is pushed to the left in FIG. 6 by the maximum amount by the coil spring 44, so that the cut pressure of the control valve does not become zero.

Furthermore, even if the coil spring 44 is damaged, the plunger 1
Since the plug 9 can only be displaced to the right up to the stepped portion 7e of the plug 7, the minimum guaranteed hydraulic pressure can be ensured.

FIG. 9 shows a third embodiment of the present invention, in which a cylindrical cam 51 is used instead of the adjusting screw 41, and a pin 5 is press-fitted into the cam groove 51a and fixed to the plug 7.
2 is inserted, and as the lever 43 rotates, the cam 51
moves left and right.

Note that the drawing is a cross-sectional view showing a part of this embodiment, and shows a state in which the cam 51 has moved the most to the left.

The configuration of other parts is the same as that shown in FIG. Furthermore, a fourth embodiment of the present invention will be described with a focus on the portion indicated by the dashed line in FIG. 2.

This embodiment is configured so that the supply of brake fluid to the brake cylinder is not cut off when the vehicle load exceeds a predetermined value, and as shown in the dashed line, the stepped piston 12 A plunger 19 is provided with a rod portion 12c on the left side, and moves between the end of the rod portion 12c and the spring case 6, that is, the stroke of the piston 12, by the upward movement of the cam 24 in accordance with a predetermined load.
The distance between the valve body 17 and the valve seat 16 is determined by the pushing amount.

In this way, when the vehicle load exceeds a predetermined value, the valve body 17 and the valve seat 16 will not close even if the piston 12 moves to the maximum due to the hydraulic pressure, so that the brake cylinder will not be closed. Brake fluid supply is never cut.

Further, a fifth embodiment of the present invention will be described with a focus on the portion indicated by the dashed line in FIG. 6.

In this embodiment, when the vehicle load exceeds a predetermined value, the spring force applied to the stepped piston is increased to reduce the amount of movement of the stepped piston, thereby increasing the amount of liquid consumed due to the movement of the piston. The aim is to make it as small as possible.

That is, the spring receiver 61 fixed to the spring housing hole of the main body 1
A second spring 62 is interposed with a free length between the ring 13 and the ring 13 with a gap l.

Therefore, when the plunger 19 is pushed in according to the load and the distance between the valve body 17 and the valve seat 16 becomes larger than the gap l, the stepped piston 12, which moves under the pressure of the hydraulic pressure, will move during its movement stroke. The spring force that comes into contact with the second spring 62 and resists the hydraulic pressure increases, and even if the amount of movement thereof is small, high hydraulic pressure can be transmitted to the brake cylinder.

Therefore, by configuring the cam curves in FIGS. 2 and 9 as curves such that the amount of pushing of the plunger 19 after the stepped piston 12 comes into contact with the second spring 62 is gradually increased, the plunger Even if the pushing amount of the stepped piston 19, that is, the amount of movement of the stepped piston 20 is reduced, the same hydraulic characteristics as with only one spring 14 can be obtained.

By reducing the amount of movement of the stepped piston 12, the secondary hydraulic pressure chamber 1 due to the movement of the stepped piston 12 is
It is possible to minimize the increase in the amount of liquid consumed due to an increase in the number of liquids.

Although the embodiments of the present invention have been described in detail above, the present invention is not limited to the above examples. A linear cam mechanism that moves the plunger by linear motion in a direction perpendicular to the axis of the plunger, or a screw structure or cylindrical cam that moves the plunger by rotational motion about its axis relative to the axis of the plunger. Although a mechanism is used, a link mechanism or a hydraulic (pneumatic) machine tank or the like that converts the displacement of the vehicle body into hydraulic pressure or pneumatic pressure and moves the plunger using this hydraulic pressure may also be used.

In addition, wires were especially used in consideration of the installation of the control valve, but
It is also possible to use a link mechanism etc. without being limited to this.

Furthermore, although a ball-shaped valve body is used as the valve mechanism for closing the liquid passage that communicates the inlet and the outlet, it may be conical or of other shapes.

Further, although the liquid passage is provided inside the stepped piston, the liquid passage may be formed between the outer periphery of the piston and the inner periphery of the cylinder in which it is accommodated. In this case, a flange is provided on the outer periphery of the piston. Alternatively, a step may be provided to serve as a valve element, and the valve seat may be moved by a plunger so that the valve element can collect dust and close the liquid passage on the outer periphery of the piston.

Since the present invention has the above configuration, it has the following effects.

■ A valve body is arranged in the liquid passage formed in the piston, and the distance between the valve body and the valve seat formed at the opening end of the liquid passage on the outlet side is adjusted by adjusting the plunger according to the loaded weight of the vehicle. Since it is possible to control the brake fluid pressure by applying operating force to the installed components only when the piston is activated, that is, when the brake is activated, this reduces fatigue of the pistons, springs, etc. that make up the installation. It becomes possible to suppress wear and the like to the necessary minimum.

- Displacement according to the vehicle's carrying load can be transmitted to the control valve using wires, etc., so the control valve can be easily installed in any desired position without being limited to near the rear axle of the vehicle, and the installation space can be reduced.

- By appropriately selecting the shape of the cam etc., various cut pressures of the control valve can be selected.

■ When using a wire, by finely adjusting its effective tensile length, the initial cutting pressure can be fine-tuned without changing the subsequent operating characteristics, making reassembly when replacing the wire extremely easy. It's easy.

■ Even if the wire of the plunger that controls the valve mechanism that determines the cutting pressure is broken or the return spring or coil spring is damaged, the plunger will be prevented from moving freely as in the previous embodiments. As a result, the cutting pressure does not become zero, and there is no need for a separate mechanism to guarantee the minimum hydraulic pressure as in the past.

[Brief explanation of the drawing]

FIG. 1 is a top view showing an embodiment of the present invention, FIG. 2 is a longitudinal sectional view of FIG. 4 and 5 are diagrams showing operating characteristic lines of the control valve, FIG. 6 is a sectional view showing another embodiment of the present invention, FIG. 7 is a side view of FIG. 6, and FIG. The figure is an abbreviated sectional view showing still another embodiment of the present invention. 1...Main body, 8...Inflow port, 9...
... Outlet, 12... Piston, 14, 62.
... Spring, 15 ... Liquid passage, 16
... Valve seat, 17... Valve body, 19...
...Plunger.

Claims (1)

[Scope of Claims] 1. A piston that is slidably inserted into a main body having an inlet and an outlet for brake fluid and is moved in one direction by brake fluid pressure; a spring biased in the opposite direction; a liquid passageway formed in the piston to communicate the inlet and the outlet; and a valve seat formed at the opening end of the liquid passageway on the outlet side. , a valve body disposed in the liquid passageway and forming a valve mechanism with the valve seat; and a valve body slidably provided in the main body, the valve body and the valve being moved in conjunction with the valve body. a plunger that adjusts the distance between the valve seat and the valve seat; and a plunger that transmits the displacement of the vehicle body according to the loaded weight of the vehicle to the plunger, and moves the valve body through the plunger to adjust the distance between the valve body and the valve seat as the loaded weight increases. A variable load brake fluid pressure control valve comprising: a transmission means that acts to move the separation distance in a direction increasing;