JPS6111823B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a valve device for controlling brake pressure at rear wheels of a vehicle.

It is known that the rear wheel brake pressure during vehicle braking generally needs to be lowered by a predetermined ratio compared to the front wheel side. This is because the vehicle's existing load or live load does not evenly press the wheels against the road surface, so that when the same braking force is applied, early wheel lock occurs on one side. The ideal distribution of brake force between the front and rear wheels has been determined for each type of vehicle, and this distribution curve generally changes as the amount of payload increases.
It is also known that the state approaches the 1/1 line from the BF/BR state.

For this reason, it is common to install a control valve in the vehicle brake hydraulic system to keep the increase in rear wheel brake hydraulic pressure lower than that of the front wheels, and it also maintains a constant level depending on the amount of vehicle carrying load. In view of the fact that the brake pressure required to obtain a braking force also varies, so-called G valves are provided which operate when a constant vehicle deceleration is achieved. This G valve is a type in which a ball that moves inertia due to constant deceleration of the vehicle blocks the flow path, thereby determining the containment pressure of the rear wheel brake pressure, or further using this for proportioning operation. It is.

However, this type of G valve had the problem of variations in confinement pressure due to several unstable factors. For example, there is a delay in the response of ball inertial movement to an increase in brake oil pressure, the influence of the flow velocity of brake oil on ball inertial movement, variation in the angle of the slope that guides ball inertial movement, and furthermore, the influence when the vehicle runs on a slope.

The present invention has been made to solve all of the various difficulties mentioned above, and detects the rotational speed of the rear wheels or their drive shafts, and when the deceleration reaches a certain value, electrically controls the control valve. This eliminates problems such as activation delays by activating the rear wheel brake pressure and determining the turning point oil pressure value for the rear wheel brake pressure. Furthermore, since the constant deceleration that determines the corner oil pressure value is generally a low value of about 0.2 to 0.3g, there is no significant difference in the deceleration state between the wheels and the vehicle, and rear wheel brake pressure control that approximates the ideal brake force distribution ratio is It becomes possible.

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

Embodiment 1 In Fig. 1, 1 is a wheel that rotates integrally with the rear wheel, 2 is a sensor that detects the number of teeth passing through this wheel 1, and 3 is a sensor that detects the rotational speed of the wheel based on a frequency signal from the sensor 2. This is a control circuit that issues a signal when the deceleration during braking exceeds a preset constant value, and is realized using known technology. 4 is an electromagnetic switching valve that switches from a normally open flow state a to a closed flow state b in response to a signal from the control circuit 3;
5 is the master cylinder, 6 is the rear wheel brake device, 7
is a control valve interposed between the hydraulic pressure transmission paths 8 and 9 connecting the master cylinder 5 and the rear wheel brake device 6, and the stepped cylinder 1 formed in the body 10.
A compression spring 14 is stretched between the stepped cylinder 12 that is slidably fitted over the large and small diameter portions of the pistons 1 and 11', and the adjustment piston 13 that is slidably fitted to the small diameter portion 11. 13 are expanded and biased toward both ends. 15 is the adjustment piston 13
is an adjustment oil chamber facing the end of the electromagnetic switching valve 4.
It is connected to the master cylinder 5 via. 1
6 is a stepped piston 12 and a stepped cylinder 11,1
1' is an input oil chamber surrounded by stepped parts,
It is connected to the master cylinder 5 via a hydraulic pressure transmission path 8 . An output oil chamber 17 faces the large diameter end of the stepped piston 12, and is connected to the rear wheel brake device 6 via a hydraulic pressure transmission path 9. Reference numeral 18 denotes a check valve built into the stepped piston 12, and the poppet 20 pressed by the spring 19 normally locks onto the wall surface of the valve body 10 and separates from the valve seat 21, thereby opening the input/output oil chamber 16, 17, and when the stepped piston 12 moves toward the small diameter part on the left side in the figure, it comes into contact with the valve seat 21 and connects the input/output oil chamber 1.
6 and 17 are configured to cut off communication.

Next, its operation will be explained.

At the time of braking, the hydraulic pressure from the master cylinder 5 is first transmitted to the input oil chamber 16 and then transmitted to the adjustment hydraulic pressure 15 via the electromagnetic switching valve 4. At this time, the check valve is in communication, so the output oil chamber 1
Hydraulic pressure is transmitted from 7 to the rear wheel brake device 6.
Therefore, the front and rear brakes increase at a ratio of 1/1. In this hydraulic state, the adjustment piston 13 has PiA ₁ (Pi: output oil pressure of the master cylinder 5, A ₁ : internal cross-sectional area of the small diameter portion 11 of the stepped cylinder).
A force of P ₀ A ₂ − Pi (A ₂ − A ₁ ) (P ₀ : rear wheel brake device 6
The input oil pressure, _A2 : internal cross-sectional area of the large diameter portion 11' of the stepped cylinder) acts on the left side of the figure. In the above-mentioned state, Pi=P ₀ =P, so the compression spring 14 is compressed, but the adjustment piston 13 and stepped piston 12 as a whole are PA ₁ → (i) PA ₂ −P(A ₂ − A ₁ )=PA ₁ ← (ii) The forces in the left and right directions in the figure are balanced, and the communication of the check valve 18 is maintained.

When the wheels are braked by the brake action and the deceleration of the rear wheels exceeds a predetermined constant value, the control circuit 3
The electromagnetic switching valve 4 shifts to the closed state shown in b in the figure in response to a signal from. Therefore, the inside of the adjustment oil chamber 15 is maintained at the current oil pressure value Pc, and the adjustment piston 13 remains stationary. After this, the force acting on the stepped piston 12 is P (A ₂ − A ₁ ) + F → (iii) PA ₂ ← (iv) in the left and right direction in the figure, and the check valve 18 communication is cut off. Therefore, approximately the containment pressure Pc of the adjustment oil chamber 15
The corner oil pressure value of the rear wheel brake pressure is determined in a substantially proportional relationship to the amount of compression of the compression spring 14 determined by =F/ _A1 , and thereafter increases at the rate of tanθ= _A2 - _A1 / _A2 . be done.

When the brake is released, the oil pressure in the input oil chamber 16 becomes zero, and the oil pressure is released from the output oil chamber 17 via the check valve 18. Further, the electromagnetic switching valve 4 returns to its initial state when the brake switch is turned off or the deceleration decreases.

In this way, with the valve device of this example, the containment pressure of the rear wheel brake pressure is determined based on the rotational speed of the wheels, and the problem of variations in the pressure is resolved and, for example, if a failure occurs in the front wheel hydraulic system, the entire vehicle When the braking force is insufficient, by inputting an appropriate failure detection signal to the control circuit 3 to prevent the output of the electromagnetic switching valve operating signal, the operation of the valve device can be completely stopped. There is also the advantage of being able to do so.

Embodiment 2 In this embodiment, as shown in FIG. 2, the existing proportioning valve and the valve device of the present invention are combined.

To briefly explain the structure of the proportioning valve, a stepped middle cylinder member 22 (adjusting piston) biased by a fixed spring 27 is arranged in the valve chamber, and the middle cylinder 23 facing the blind hole cylinder 24 is arranged in the valve chamber. The large diameter portion of the control piston 25, whose small diameter portion has been inserted and slid into the blind hole cylinder 24, is inserted into the middle cylinder 23 to a predetermined position by means of the control spring 26, and the middle cylinder member 2
The output oil chamber 30 in the middle cylinder 23 is constructed by constructing a valve mechanism for opening and closing the flow path by the cooperation of the valve seat 28 fixed to the cylinder 2 and the large diameter part of the control piston 25.
and an input oil chamber 29 in which the shaft portion of the control piston 25 is located. The output oil chamber 30 is communicated with a rear wheel brake device, and the input oil chamber 29 is communicated with a master cylinder.

Further, the plug 32 that closes the valve chamber is formed with a protrusion that enters the middle cylinder 23 and is slidably fitted thereto, so that the middle cylinder member 2
A regulating oil chamber 31 is formed, which the large diameter portion of No. 2 faces.

In such a configuration, the slow rising characteristic of the rear wheel brake oil pressure, that is, the output oil pressure, is determined by the cross-sectional areas A ₃ and A ₄ of the large and small diameter portions of the control piston 25 and the spring force of the control spring 26. The corner oil pressure value is determined. If the middle cylinder member 22 is moved to the left side of the input oil chamber 29 in the figure, the compression distance of the control spring 26 required to open and close the flow path of the valve mechanism increases, increasing the corner oil pressure value. be able to.

In this example, the movement of the middle cylinder member 22 to the left in the figure is configured to be performed by a valve device interposed in a hydraulic path 38 connecting the input oil chamber 29 and the adjustment oil chamber 31. That is, 33 is the above-mentioned Example 1
A solenoid is excited by a signal from the control circuit (not shown) described in 2. 34 is an armature that moves by the excitation of this solenoid 33. 35 is a valve body disposed in the hydraulic path 38. Due to the pressing force of the spring 36, it separates from the valve seat 37 and communicates the flow path, and as the armature 35 moves, it moves integrally and comes into contact with the valve seat 37, blocking communication of the flow path.

With the valve device having such a configuration, the brake oil pressure Pc when the wheel deceleration exceeds a certain value is contained in the adjustment oil chamber 31, and the brake oil pressure Pc is contained in the adjustment oil chamber 31.
2 is the balance between the large diameter end area A ₄ facing the adjustment oil chamber 31, the small diameter end area A ₃ facing the input oil chamber 29, and the spring force of the control spring 26 and fixed spring 27 acting on the middle cylinder member 22. It will move to the desired position and stand still. It will be understood from the above explanation that the amount of movement from this initial position is proportional to the value of the containment oil pressure Pc.

As described above, the valve device according to the present invention has the following features:
By controlling the rear wheel brake hydraulic pressure based on the wheel deceleration rather than the vehicle deceleration, high responsiveness is obtained and the problem of variation is reduced.Furthermore, since the control is based on electrical commands, the front wheel hydraulic system The practical benefits are extremely large, such as ensuring that the braking force of the entire vehicle is compensated in the event of failure.

[Brief explanation of drawings]

FIG. 1 is an explanatory cross-sectional view of a valve device according to a first embodiment of the present invention, and FIG. 2 is a cross-sectional view of a valve device combined with proportioning according to a second embodiment of the present invention. 1... Wheel, 2... Sensor, 3... Control circuit, 4... Solenoid switching valve, 5... Master cylinder,
6... Rear wheel brake device, 7... Valve device,
8, 9...Hydraulic pressure transmission path, 10...Valve body, 11, 11'...Stepped cylinder, 12...Stepped piston, 13...Adjustment piston, 14...Compression spring, 15...Adjustment oil chamber, 16...Input oil chamber, 17...Output oil chamber, 18...Check valve, 19
... Spring, 20 ... Poppet, 21 ... Valve seat, 22 ... Middle cylinder member, 23 ... Middle cylinder, 24 ... Blind hole cylinder, 25 ... Control piston, 26 ... Control spring, 27 ... Fixed spring, 28...Valve seat, 29...Input oil chamber, 30...Output oil chamber, 31...Adjustment oil chamber, 32
...Plug, 33 ... Solenoid, 34 ... Armature, 35 ... Valve body, 36 ... Spring, 3
7... Valve seat, 38... Hydraulic path.

Claims (1)

[Claims] 1 The control piston, which has a small pressure-receiving area facing the input oil chamber communicating with the master cylinder and a large pressure-receiving area facing the output oil chamber communicating with the rear wheel brake system, is normally moved toward the output oil chamber side by the pressing force of the control spring. A vehicle rear end brake hydraulic control system configured to be biased to open a valve mechanism provided in the input/output oil chamber communication passage, and to close the valve mechanism by moving against the control spring by hydraulic action. In the valve device, an adjustment oil chamber communicates with the input oil chamber via a normally open flow path opening/closing valve, and an adjustment chamber with one end facing the adjustment oil chamber and with the bottom end engaged with the control spring. A piston and a control circuit that detects the wheel rotational speed and closes the flow path opening/closing valve when the deceleration during control exceeds a certain value are provided, and the adjustment oil chamber is controlled when the flow path opening/closing valve is closed. A valve device characterized in that the spring force acting on the control piston of the control spring is increased by movement of the regulating piston substantially proportional to the containment pressure.