JPS6233107B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a deceleration sensing type proportioning valve that appropriately distributes front and rear wheel braking force when braking a vehicle in accordance with fluctuations in the load capacity W of the vehicle.

It is generally known that in order to maintain a suitable slip ratio between the wheels and the road surface and obtain effective wheel braking force, it is necessary to apply a certain percentage of braking force to the rear wheels compared to the front wheels. There is.
This is because the force that presses the wheels against the road surface is greater for the front wheels, and the ideal brake force distribution ratio between the front and rear wheels is affected by the change in the directionality of the inertial force during braking, which is the curve a in Figure 1. , b, and c. Since the increase in load carrying capacity W mainly appears as an increase in the force that presses the rear wheels against the road surface, the above curve asymptotically approaches the front and rear wheel brake ratio F _R /Ff = 1/1 as the load increases from a to b to c. It also has the property of

However, since it is desirable to approximate the actual front and rear brake force ratio to the curve showing the ideal distribution ratio, conventional proportioning has been applied to the hydraulic path connecting the hydraulic power source (master cylinder) and the rear brake system. In some cases, a control valve such as a valve is provided.

However, in conventional valves of this type, the hydraulic pressure transmitted to the output oil chamber shifts to a state of a slow rate of increase with a predetermined constant value as a turning point, and this turning point oil pressure value does not change. Therefore, in vehicles such as trucks with large load fluctuations, there is a drawback that the deviation between the ideal curve and the actual control characteristic line becomes large.

This problem can be solved by, for example, detecting the relative displacement due to load fluctuations between the vehicle body and the axle using an appropriate detection mechanism, and linking this detection mechanism to change the corner oil pressure value of the valve. Although this problem could be solved by adding a so-called load response mechanism that has the function of increasing the load, it also led to problems such as a complicated structure, an increase in the number of parts, and an increase in cost.

Therefore, the present applicant has provided a stepped piston that faces the control piston or is slidably fitted with the control piston, sandwiching the input oil chamber in the cylinder, and also opens and closes the flow path in cooperation with the valve seat of the control piston. A control spring that determines the starting point of operation (i.e., corner point oil pressure) is stretched between the stepped piston and the control piston, and the large diameter end of the other end of the stepped piston enters the input oil chamber via the G valve. A deceleration-sensing proportion is configured to compress the control spring approximately in proportion to an increase in the hydraulic pressure sealed in the regulating oil chamber by facing the communicating regulating oil chamber, thereby increasing the corner oil pressure value. We are developing a shock valve.

The present invention is a further improvement on this type of valve. In other words, as mentioned above, this valve is of a type that increases the corner oil pressure value by compressing the control spring, so the control piston and stepped piston are positioned with the control spring and input oil chamber in between, and the cylinder It was necessary to have a relatively large axial length.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide a deceleration-sensing proportioning valve having a structure suitable for solving the problems of the prior art and realizing miniaturization of the valve. .

The deceleration-sensing proportioning valve of the present invention, which was made to achieve the above object, is characterized by the fact that the hydraulic force from the output oil chamber exceeds the hydraulic force from the input oil chamber. a control piston that can move toward the input oil chamber while compressing a control spring; and a valve seat that divides the inside of the cylinder into two oil chambers, the input oil chamber and the output oil chamber, and that the moving control piston comes into contact with. When the hydraulic force applied to the control piston exceeds a certain value, the control piston and the valve seat cooperate to open and close the normally open flow path formed in the valve seat, thereby increasing the amount of water in the output oil chamber. A proportioning valve that gradually increases output oil pressure includes a stepped piston whose large diameter end is divided into a pressure receiving surface desired for the output oil chamber and the adjustment oil chamber, and whose small diameter end faces the input oil chamber; An adjustment spring that presses the stepped piston toward the output oil chamber is provided so that the stepped piston can be moved toward the input oil chamber while compressing the adjustment spring by hydraulic force, and the valve seat is provided to follow the movement of the stepped piston, and furthermore, the adjusting oil chamber is connected to the input oil chamber via a G valve that cuts oil pressure transmission at a constant vehicle deceleration, and when the G valve cuts off oil pressure transmission, the adjustment oil chamber The stepped piston is moved by hydraulic pressure sealed in an adjustment oil chamber to increase the amount of compression of the control spring required for the control piston to engage the valve seat.

According to such a configuration, the movement of the valve seat accompanying the movement of the stepped piston increases the amount of movement required for the control piston to come into contact with the valve seat, and therefore, the amount of movement of the control spring at this time increases. The amount of compression also increases, and the hydraulic pressure point value increases accordingly. Since the movement directions of the control piston and the stepped piston are the same, it is possible to adopt a structure in which the stepped piston holds the control piston, and as a result, the entire valve can be made smaller. You can obtain the following characteristics.

The present invention will be described below based on embodiments shown in the drawings.

In FIG. 2, 1 is a valve body, 2 is a stepped cylinder, 3 is a plug that closes the large diameter part of the stepped cylinder 2, and a port 4 and a small diameter cylinder 5 are connected to a rear wheel brake device (not shown). is formed. Reference numeral 6 denotes a stepped piston that is slidably fitted to the stepped cylinder 2, and a small-diameter extending portion 7 is provided from the large-diameter end to slide-fit to the small-diameter cylinder 5 of the plug 3; The spring force F ₂ of the adjustment spring 8 is biased from the side so as to lock the plug 3.

9 is a flow path passing through the axial center of the stepped piston 6;
10 is an output oil chamber that communicates with the port 4 and the flow path 9 and faces the end face of the small diameter extension 7 of the stepped piston 6; 11 is the small diameter portion of the stepped cylinder 2 and the small diameter end of the stepped piston 6; It is an input oil chamber facing the section, and is communicated with a master cylinder (not shown) via a port 12, and is also communicated with an output oil chamber 10 via a flow path 9 in the stepped piston 6. .

Reference numeral 13 denotes an adjustment oil chamber to which the large diameter end of the stepped piston 6 excluding the small diameter extension 7 faces, and is communicated with the input oil chamber 11 via the G valve mechanism.

This G valve mechanism is a known one, and the ball 15 is guided by a guide surface 14 that forms an elevation angle of θ with respect to the vehicle traveling direction (indicated by the arrow in the figure), and the ball 15 is inertia caused by a constant deceleration g _c when the vehicle is braked. Move and valve seat 1
6 and blocks communication of the flow path 17.

Reference numeral 18 denotes a control piston disposed within the input oil chamber 11, one end of which is fitted and slid into the blind hole 19 of the valve body 1, and the other end provided with a large diameter head 20 forming the valve body. The stepped piston 6 is inserted into a recess 21 having the same diameter as the small-diameter extending portion 7 formed at the small-diameter end of the stepped piston 6 .

22 is a flange portion of the control piston 18;
The locking plate 24 is moved by the spring force _F1 of the control spring 23.
The stepped piston 6 is biased so as to be engaged with the stepped piston 6 via the stepped piston 6. 25 is a stepped piston 2 by a spring 26.
It is a valve seat fixed in the small-diameter end recess 21 of the control piston 18, and normally has a certain gap with the head 20 of the control piston 18 to open a flow path that communicates the input and output two oil chambers 10, 11. The piston 18 moves and its head 2
0 is provided so as to close the flow path when the valve seat 25 comes into contact with the valve seat 25.

Next, its operation will be explained.

When not braking, the control piston 18 is activated as shown in the figure.
and the stepped piston 6 are biased to the left in the figure by the biasing spring force, and the input oil chamber 11 and the output oil chamber 10
are in communication, and the G valve mechanism is also connected to the flow path 17.
The input oil chamber 11 and the adjustment oil chamber 13 are communicated by opening.

When hydraulic pressure is transmitted to the input oil chamber 11 at the beginning of braking, this input hydraulic pressure Pi is transmitted to the output oil chamber 10 via the flow path 9, and at the same time, the input oil pressure Pi is transmitted to the output oil chamber 10 through the flow path 1 of the G valve mechanism.
It is also transmitted to the regulating oil chamber 13 via 7.

In this case, the input oil pressure Pi, the output oil pressure Po, and the oil pressure Pa in the adjustment oil chamber are in the state of Pi = Po = Pa, and the oil pressure acts on the control piston 18 and the stepped piston 6 in the left-right direction in the figure as follows. do.

Control piston 18: →PoA ₁ ...(1) ←Pi (A ₁ - _{A 2} ) ...(2) (where A ₁ : Cross-sectional area of control piston head 20 A ₂ : Cross-sectional area of control piston shaft) Stepped piston 6: →PoA ₃ +PaA ₄ ...(3) ←PiA ₅ ...(4) (However, A ₃ : Cross-sectional area of stepped piston small diameter extension part 7 A ₄ : (Stepped piston large diameter section Area) - A ₃ (A ₅ : Cross-sectional area of the small diameter part of the stepped piston) Here, A ₁ > A ₁ - A ₂ and A ₃ + A ₄ > A ₅ , respectively (1) > (2) > , (3)>(4), and as the oil pressure of the control piston 18 and the stepped piston 6 increases, the urging force to move them to the right in the figure increases.

If the spring forces F ₁ and F ₂ of the control spring 23 and adjustment spring 8 are exceeded, the movement to the right in the figure will occur.

Assuming that the stepped piston 6 is stationary, the control piston 18 begins to move to the right in the figure as PoA ₁ > Pi (A ₁ − A ₂ ) + F ₁ (5), and PoA ₁ = Pi (A ₁ − A ₂ ) + F ₁ + k ₁ x ₀ ...(6) (where k ₁ : Spring constant of the control spring x ₀ : When the amount of clearance between the control spring head and the valve seat is reached, the control piston _The head 20 of No. 18 comes into contact with the valve seat 25, and after that, Po= _A1 - _A2 / _A1Pi - _F1 + _k1x0 / _A1 ...
By maintaining the balance of (7), an increase in the output oil pressure Po can be obtained.

From the above, from equation (6), Pi=Po=F ₁ +k ₁ x0/A ₂ =Pc...(8) is the corner oil pressure Pc, and then tanθ=A ₁ −A ₂ /A ₁
<1 output oil pressure Po (equivalent to rear wheel brake force)
This results in a gradual increase in

On the other hand, considering the stepped piston 6, in this example, the spring force of the control spring 23 is also biased via the control piston 18, so the control piston 16 is (Po=Pa=Pi) PoA ₂ + PoA ₃ + PaA ₄ >PiA ₅ +F ₁ +F ₂ ...(9) It starts to move to the right in the figure while accompanying the control piston 18. Then, when the vehicle deceleration reaches a certain value g _c due to the braking action, the G valve mechanism closes the flow path 17, the adjustment hydraulic pressure Pa is sealed, and the position of the stepped piston 6 at that time is PoA ₂ + PoA ₃ + PaA ₄ =PiA ₅ +F ₁ +k ₁ x′+F ₂ +k ₂ x′ ……(10) (where k ₂ : Spring constant of adjustment spring 8 x′ : Travel amount of stepped piston) is determined by x′ and stops there. Become something. Therefore, as the head 20 of the control piston 18 repeatedly moves away from and separates from the valve seat 25, which is stationary at that position, a gradual increase in the output oil pressure Po is obtained. The spring force of the control spring 23 that determines is F ₁ + k ₁ x ₀ → F ₁ + k ₁ (x ₀ + x'), and an increase in the corner oil pressure value Pc is approximately proportional to the amount of movement of the stepped piston 6. It is understood that this will happen.

Therefore, the moving amount x' of the stepped piston 6 is proportional to the oil pressure value Pa sealed in the regulating oil chamber 13, and this is because the oil pressure value Pa at the time when the flow path 17 of the G valve mechanism is closed is known, and the load capacity of the vehicle is As a result, the value of the corner oil pressure Pc is approximately proportional to the variation in the vehicle's load, and the stepped piston 6
Since the control of the corner oil pressure Pc can be carried out from the time when the vehicle is loaded with zero load (when the vehicle is empty) to when the vehicle is fully loaded (when the vehicle is at constant load), when the vehicle is empty, the movement amount x' of the stepped piston 6 can be set to zero, Practically speaking, it is desirable to set the spring forces F ₁ and F ₂ of the adjustment spring 8 and the control spring 23 accordingly.

In this example, the control spring 23 is indirectly engaged with the stepped piston 6 via the locking plate 24; however, depending on the movement of the stepped piston 6, the valve seat 24 It may be configured such that only the control piston 18 moves, thereby increasing the clearance x0 between the head 20 of the control piston 18 and the valve seat 24. It is easily understood that the same control operation can be obtained in this case as well, except that the values of the spring forces F ₁ , F ₂ and the spring constants k ₁ , k ₂ of the control spring 23 and adjustment spring 8 are changed. By the way.

FIG. 3 shows another embodiment of the present invention, except that the fitting relationship between the stepped piston 106 and the plug 103 and the positions of the output oil chamber 110 and the adjustment oil chamber 113 are changed. It is similar to

That is, the stepped piston 106 has a relatively large-diameter flow path 109 formed at its axial center, into which an extension 103' formed in the plug 103 is fitted, and the output oil chamber 110 is connected to the stepped piston 106. The adjusting oil chamber 113 is provided in a position where the large diameter end of the stepped piston 106 faces. Therefore, the movement of the stepped piston 106 is independent of the oil pressure Po of the output oil chamber 110, and the adjustment oil chamber Pa,
Although it is supposed to be balanced by the input oil pressure Pi, the spring forces F ₁ and F ₂ of the adjustment spring 108 and the control spring 123, the substantial operating relationship and control characteristics can be obtained almost the same as in the previous embodiment. It is.

As described above, the deceleration sensing type proportioning valve according to the present invention is provided with a stepped piston that moves relative to the control piston by hydraulic pressure so as to reduce the span, and the relative movement causes the control piston to spring. Compared to the conventional structure in which the control spring that biases the force is compressed and the force of the bias spring is increased, the stepped piston is controlled by moving parallel to and in the same direction as the control piston. It is configured to move the position of the valve seat that cooperates with the piston, making it possible to shorten the length of the valve in the cylinder direction, resulting in miniaturization, which has great practical benefits. It is something.

[Brief explanation of the drawing]

Fig. 1 is a diagram showing the characteristics of the deceleration sensing type proportioning valve of the present invention in comparison with an ideal curve, Fig. 2 is a vertical cross-sectional view of the valve showing an embodiment of the present invention, and Fig. 3 is FIG. 7 is a vertical cross-sectional view of a valve showing another embodiment. 1,101... Valve body, 2,102...
Stepped cylinder, 3,103...Plug, 103'
...Extending portion, 4,104...Port, 5...Small diameter cylinder, 6,106...Stepped piston, 7...
Small diameter extension part, 8,108...adjustment spring,
9,109...Flow path, 10,110...Output oil chamber, 11,111...Input oil chamber, 12,112...
...Port, 13,113...Adjustment oil chamber, 14,1
14...Guide surface, 15,115...Ball, 1
6,116... Valve seat, 17,117... Channel, 1
8,118... Control piston, 19,119...
Blind hole, 20,120... Head, 21,121...
Recessed portion, 22, 122...Flange, 23, 123
... Control spring, 24,124 ... Locking plate,
25,125...valve seat, 26,126...disc spring.

Claims (1)

[Claims] 1 A control piston that can move toward the input oil pressure side while compressing a control spring due to the hydraulic force from the output oil chamber that exceeds the hydraulic force from the input oil chamber, and a control piston that can move toward the input oil pressure side while compressing the control spring, The control piston is divided into two oil chambers, and has a valve seat that the moving control piston comes into contact with. In the proportioning valve, the large diameter end is connected to the output oil chamber and the adjustment oil chamber by opening and closing a normally open flow path formed in the valve seat to slowly increase the output oil pressure in the output oil chamber. A stepped piston that is divided into desired pressure-receiving surfaces and whose small diameter end faces the input oil chamber, and an adjustment spring that presses the stepped piston toward the output oil chamber are provided, and the stepped piston is adjusted by hydraulic force. The valve seat is configured to move toward the input oil chamber while compressing the spring, and the valve seat is provided to follow the movement of the stepped piston, and the adjusting oil chamber transmits hydraulic pressure at a constant vehicle deceleration. The stepped piston is connected to the input oil chamber via the G valve to be cut, and the stepped piston is moved by the hydraulic pressure sealed in the adjustment oil chamber when the G valve is transmitted to cut, and the control piston reaches the valve seat. 1. A deceleration-sensing proportioning valve, characterized in that it is configured to increase the amount of compression of the control spring required for.