JPS5810671Y2 - Load responsive proportion valve - Google Patents

Description

[Detailed description of the invention] This invention is a brake fluid pressure reducing device for a two-axle vehicle with two rear axles. This invention relates to a responsive proportion valve.

Conventional load-responsive proportion valves - In the case of a braking circuit with two rear wheels and separate pressure reduction circuits, two proportion valves are required.
Therefore, there are disadvantages in that it is difficult to secure a mounting location and that it is expensive.

Therefore, the applicant first provided a load-responsive proportion valve that solved these drawbacks (see Japanese Patent Application No. 140332 of 1971 and Japanese Patent Application Laid-open No. 50089769).
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This proportion valve is a brake fluid pressure reducing device consisting of a live load sensing part and a hydraulic pressure control part having a first plunger part and a second plunger part. The actuator plate, supported by The plungers of the second plunger portion are respectively actuated via adjustment screws, thereby performing two systems of proportional action.

The present invention improves the previously provided load-responsive proportion valve so that even if one of the two systems is damaged, the other system can perform an appropriate braking action. This is what I did.

The present invention will be described below with reference to embodiments shown in the drawings.

A vehicle brake system using a proportion valve according to the present invention will be explained with reference to FIG.

When the pedal 1 is depressed, the liquid from the tandem master cylinder 2 is separated and discharged from chambers 3a and 3b.
The liquid in the chamber 3a passes through the passage 4 and is supplied to the brake booster 5a, in which it acts as a command pressure.

There, the boosted liquid passes through one passage 6, one is led to the front wheel braking cylinder 8 through a pipe 7, the other passes through a passage 9, passes through the first plunger portion 11a of the proportion valve 10, and is led to the piping 12. , and is later led to the wheel braking cylinder 13.

Similarly, the fluid in the chamber 3b passes through the passage 14 and is supplied to the brake booster 5b□.

It acts as a command pressure in the brake booster.

The boosted liquid then passes through the first passage 15, the second plunger portion 11b of the proportion valve 10, and the pipe 16 to be guided to the rear and front wheel braking cylinders 1γ.

The proportion valve according to the present invention will be explained with reference to FIG.

The proportion valve 10 has a first plunger portion 11a
The second plunger portion 11b includes a hydraulic pressure control portion and a load sensing portion 18.

The first plunger portion 11a is. a chamber 19 leading to the pipe 9;
Chamber 20 communicating with piping 12 and second plunger portion 11
Each has a chamber 21 communicating with it via a conduit 46 on the b side,
The chamber 20 and the chamber 19 communicate with each other through a passage 22 and a passage 23, and through a chamber 24, respectively.

A steel ball 27 is housed in the chamber 24 so as to be in contact with the seat 26 by a spring 25.

The plunger 28 has a large diameter portion 29 , a medium diameter portion 30 and a small diameter portion 31 , and the pressure inside the chamber 20 is equal to the area of the large diameter portion 29 minus the area of the small diameter portion 310 . The pressure inside the chamber 21 acts on the area of the large diameter portion 29 minus the medium diameter portion 300.

This plunger 28. The steel ball 27 is arranged so as to be separated from the seat 26 by the force Fa transmitted from the load sensing portion 18.

The second plunger portion 11b is the first plunger portion 11a.
With the same configuration as above, pipes 15° 16 communicate with each chamber 19', 20', and further communicate with the chamber 21' from the system on the first granger section 11a side via a pipe line 46', and the large diameter section 29 ', medium diameter part 30', and small diameter part 31'
The plunger 28' is arranged so that the force Fb transmitted from the load sensing portion 18 causes the steel ball 27' to be moved away from the seat 26'.

In FIG. 1, the same reference numerals as the first plunger part 11b with a dash attached thereto are the same elements.

The load sensing portion 18 has the tip of a leaf spring 33 connected to a lever 32 fixed to a placket 34 fixed to one of the rear wheel axles via a wire or rod 35, and the proportion valve 10 is fixed to the chassis frame.

The force generated by the displacement between the rear wheel axle and the chassis frame is
Rod 35. Leaf spring 33. It extends to the retainer 37 via the lever 32 and the rod 36, and acts in the opposite direction to the biasing force direction of the spring 338 that biases the retainer.

The plate 39 is in contact with the retainer 37 and further engages with the actuator plate 40 at its center, transmitting a force F obtained by subtracting the force generated according to the load from the biasing force of the spring 38 to the actuator plate 40. .

The actuator plate 40 has a pin 4 attached to the plate 39.
The plungers 28 and 28' of the first and second plunger portions are pressed by plugs 42 and 42' fitted near both ends thereof.

This actuator plate 40 is prevented from moving in the direction of the plunger part by a stopper 43 and by a load sensing part 1.
Stopper 4 disposed in casing 44 for movement in eight directions
5, respectively.

First, the operation of the plunger according to the present invention will be explained with reference to the principle diagrams shown in FIGS. 2 and 3.

To simplify the explanation, the force of the spring 250 biasing the steel ball 27 and the diameter of the rod 47 that presses the steel ball are ignored, and the area of pressure acting on the large diameter portion 290 of the plunger 28 on the side of the chamber 19 is ignored. (Referring to the area where hydraulic pressure actually acts) is A.

The pressure acting area B on the chamber 21 side, the pressure acting area on the medium diameter section 300 chamber 20 side is C1. Now, assuming that the pressure in each chamber 19, 20° 21 is the same (pressure Pky/ci), the right direction in Figure 1 is If positive, the force fa exerted on the plunger 28 is.

Volume = (B+C)-A=(C-A) 10th class... ■If the system of the second plunger part 11b is damaged here, the chamber 2
Since the pressure inside 1 becomes zero, the force f'a exerted on the plunger 28 in this case is 1ゝ-(C-A)......■
Further, the hydraulic pressure of the first plunger portion 11a is acting on the chamber 21' of the second plunger portion 11b.

The force f'b exerted on the plunger 28' is equal to B
...■ Comparing the above formulas ■ and ■, it can be seen that formula 0 is smaller by B.

That is, when the system of the second plunger portion 11b is damaged, the force f'a exerted by the hydraulic pressure on the plunger 28 is smaller than the force fa exerted by the hydraulic pressure on the plunger 28 under normal conditions.

Here, if the relationship between the pressure acting areas is, for example, C-A<o, then f'a is negative, that is, the plunger 28 is moved to the left by the action of the hydraulic pressure regardless of the action of the load sensing section 18, No depressurization is performed.

Contrary to the above, if the relationship between the pressure acting areas is C-A>o, then f'a is positive, that is, the hydraulic pressure is fa, and c presses the plunger 28 to the right with a small force f'a. .

Next, the overall operation of the proportion valve 10 will be explained in the following two steps.

In the first stage, on the first plunger portion 11a side, the force Fa transmitted from the load sensing portion 18 causes the plunger 2 to
8 moves and holds the steel ball 2T at the tip of the sheet 2.
It is away from 6.

In this state, the hydraulic gutter 9. is boosted by the brake booster 5a due to the hydraulic pressure in the mask cylinder 20 chamber 3a.
It is led to chamber 24 via chamber 19 and passage 23.

Further, it enters the chamber 20 through the passage 22, passes through the piping 12,
It later enters the wheel braking cylinder 13.

On the other hand, the load sensing portion 1 in the second plunger portion 11b
Similarly, the steel ball 27' is separated from the seat 26' by the force FbK transmitted from B, and the liquid, which is boosted by the brake booster 5b by the hydraulic pressure in the mask cylinder 20 chamber 3b, passes through the piping 15. It enters the front wheel brake cylinder 17.

The input hydraulic pressure and output hydraulic pressure before and after entering the first plunger portion 11a or the second plunger portion 11b4C are equal.

In the second stage, on the first plunger portion 11a side, as the input hydraulic pressure gradually increases, the hydraulic pressure that has entered the chamber 20□ acts on the outer surface of the medium diameter portion 30 of the plunger 28, and the force generated thereby and the chamber The input hydraulic pressure in 19 is the plunger 2
The difference between the force and the force generated by acting on the outer surface of the large diameter portion 29 of 8 overcomes the force Fa and moves the plunger 28 in the direction of the load sensing portion 18.

Accordingly, the steel ball 27 closes the seat 26.

As the input hydraulic pressure increases further, the hydraulic pressure in chamber 19 moves plunger 28 in the opposite direction.

Accordingly, the steel ball 27 separates from the seat 26, so that the liquid input to the chamber 240 enters the chamber 20 through the passage 22.

The hydraulic pressure then moves the plunger 28 in the direction of the load sensing portion 18 in the same manner as above, causing the steel ball 27 to close the seat 26 again.

In this way, the plunger 28 opens and closes the seat 26 to adjust the input hydraulic pressure PFa and the output hydraulic pressure PRa.

At this position, the seat 26 is closed and stopped.

(However, A, B, and C represent the pressure acting areas used in the above formulas (1) and (2), and the hydraulic pressure from the second plunger side exerted on the chamber 21 was assumed to be the same as the input hydraulic pressure PFa.

) On the other hand, in the second plunger portion 11b, the plunger 28' opens and closes the seat 26' to adjust the input hydraulic pressure PFb.
and output hydraulic pressure PRb.

At this position, the seat 26' is closed and stopped.

In this way, the proportion pulp 10 is connected to the load sensing part 1.
The proportion action starting hydraulic pressure is determined by the component force Fa or Fb of the force F transmitted from 8.

Note that the relationship between each component force Fa, Fb and F is as follows.

Each plunger 28 on the second plunger side 11at11b.
The distances from 28' to pin 41 are La and L, respectively.
Let's say b.

It is.

Next, the load sensing portion 18 will be explained.

When the rod 35 is displaced due to the load capacity of the vehicle, the leaf spring 3
3 changes the biasing force of the spring 38, and the actuator plate 40 applies force F to the plugs 42, 42 via the plate 37.
' to each plunger 28°28'.

In the embodiment of the present invention (FIG. 2), if an abnormality occurs in one of the hydraulic pressure systems, for example, if the piping on the second plunger portion 11b side is broken and the hydraulic pressure does not increase, the first plunger portion The hydraulic pressure in the chamber 21 of 11a becomes zero, and the plunger 28 moves upward in the figure with a small force, regardless of Fa, as described above.

This substantially eliminates or reduces the pressure reducing effect on the first plunger portion 11a side, thereby reducing the wheel braking force later.

The proportion valve according to the present invention allows two systems of proportioning to be performed with one proportion valve, and can arbitrarily change both pressure reduction ratios.

Furthermore, even if there is an abnormality in one of the pressure reducing systems, the proportion valve according to the present invention can sufficiently transmit the force transmitted to the other plunger compared to normal conditions, thereby transferring fluid pressure to the braking cylinder without substantially reducing the pressure. It can be made to work.

Further, the characteristics of this valve are determined by the balance of forces applied to the plunger when the ball valves 26 and 27 are closed.

Therefore, as explained in FIG. 3, when both hydraulic systems are normal, the force of the plunger 28 is balanced.

PRa-C+PFa-B-PFa-A+FaAlso, if one hydraulic system is damaged.

From the balance of power of Ja28, PRa-C=PFa-A+Fa plan becomes.

Based on these two equations, the characteristics of this valve are as shown in FIG.

In other words, under normal conditions, the slope is the peak θ as shown by the solid line
If one of the hydraulic systems is damaged, the slope becomes tanθ=tese, as shown by the solid line Y, and if one of the hydraulic systems is damaged,
4, the slope when one hydraulic system is damaged is higher than when it is normal.

In addition, as mentioned above, the hydraulic pressure breaking point PC2 when one hydraulic system is damaged
The pressure also rises from the normal hydraulic pressure point PC.

Therefore, even after PC0 under normal conditions, the output pressure P Ra t P Rb rises with a slope of tmlθ-momo1, and when one hydraulic system is damaged, PC2 rises and the slope after PC2 is even steeper. Since the output pressure increases at tanθ-1, extremely favorable characteristics can be obtained.

[Brief explanation of drawings]

Fig. 1 shows a vehicle brake system diagram using the load-responsive proportion valve according to the present invention, Fig. 2 is a longitudinal cross-sectional view of the load-responsive proportion valve according to the invention, and Fig. 3 explains the operation of the plunger. FIG. FIG. 4 is a diagram showing the characteristics of this valve. 9... Passage, io... Proportion valve, 11a... First plunger part, 11
b...Nibranja part, 12...
Piping, 15... passage. 16...Piping, 18...Load sensing part, 19°20.21...Chamber, 23...
Passageway, 24...room, 26...seat,
27...Steel ball, 28...Plunger, 29...Large diameter section, 30...
Medium diameter part, 31... Small diameter part, 40... Actuator plate, 41... Pin, 46...
...Pipeline.

Claims (1)

[Scope of utility model registration request] A hydraulic control section comprising a payload sensing section and a hydraulic control section having a first plunger section associated with one hydraulic system and a second plunger section associated with the other hydraulic system and engaged with a plate of the load sensing section. In the load-responsive proportion valve of the brake fluid pressure reducing device, in which the actuator plate is brought into contact with each plunger of the first plunger portion and the second plunger portion, the small diameter portion, large diameter portion, and medium diameter portion are attached to each plunger in this order. In addition, chambers are formed so that hydraulic pressure acts on the small diameter part side surface of the large diameter part, the medium diameter part side surface of the large diameter part, and the outer end surface of the medium diameter part. The small-diameter side chamber and the outer-end chamber of the medium-diameter portion are communicated, a hydraulic inlet passage is connected to the small-diameter side chamber of the large-diameter portion of each plunger, and a hydraulic outlet passage is connected to the outer-end chamber of the medium diameter portion of each plunger. A load-responsive proportion HARTZ that connects the large-diameter and medium-diameter side chambers to other hydraulic systems.