JPS6140614Y2 - - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to an improvement of a hydraulic control device for a vehicle brake.

In vehicle brakes, the brake hydraulic pressure for the rear wheels is controlled relative to the brake hydraulic pressure for the front wheels. So-called proportioning valves are known, and deceleration sensing valves have been proposed that sense the deceleration of a vehicle and control the operation of the proportioning valve.

Furthermore, in a hydraulic control system equipped with such a proportioning valve and a deceleration sensing valve, in order to prevent fluctuations in the operating point of the proportioning valve and stabilize the operation of the valve, especially when the vehicle is empty, a reduction is required. A speed sensing valve equipped with a check valve has been proposed.

However, when the check valve is provided, the set pressure of the check valve causes a hydraulic loss in the rear wheel hydraulic pressure during loading as shown by the shaded area A in FIG. Furthermore, when the car is suddenly braked when the vehicle is empty, the ball valve of the deceleration sensing valve tries to block the pressure oil outlet of the cylinder chamber of the sensing valve and causes the oil pressure in the cylinder chamber to rise rapidly, and as a result, The check valve may open without comparing the hydraulic pressure generated by the master cylinder, causing the operating point of the proportioning valve to fluctuate, making its operation unstable.

In order to stabilize this, it is possible to increase the set pressure of the check valve, but this increases hydraulic pressure loss during loading, as shown by B (triangular portion including A) in FIG. 2. For this reason, the braking force on the rear wheels decreases in the normal use range when loaded, and the braking force distribution on the front wheels increases, causing abnormal phenomena such as brake unilateral braking and squealing, as well as improving the feeling of the vehicle. do not have.

As a brake hydraulic control means for the rear wheels,
As shown in Japanese Patent Publication No. 38-18255, there is a main body with a chamber inclined upward in the forward direction, and the rear end of the chamber communicates with the master cylinder and the front end communicates with the rear brake. The space is divided into front and rear parts by a partition wall, and an opening made in the wall is controlled by a poppet valve, and a ball is placed in the room so as to engage with a pin of the poppet valve to keep the valve open at all times. There is an inertia valve type anti-lock device in which a cylinder is formed in the vicinity of the hydraulic pressure outlet to the rear wheel of the main body and communicates with the outlet, and a piston pushed toward the outlet by a coil spring is fitted into the cylinder to form an expansion chamber. This has no check valve,
The movement of the ball, which senses deceleration, closes the poppet valve to suppress hydraulic pressure to the rear wheels. In addition, the expansion chamber has the function of equalizing pressure fluctuations to the rear wheels and at the same time compensating for the increase in fluid required by thermal expansion of the brake drum. It is sufficiently strong to avoid surges and is independent of the poppet spring strength. Therefore, it is not possible to eliminate the loss of rear wheel hydraulic pressure due to the provision of the check valve, and it is not possible to eliminate operational instability caused by sudden fluctuations in hydraulic pressure during sudden braking.

Further, in a brake control device equipped with a proportioning valve and a deceleration sensing valve as described above,
Master cylinder, control valve (proportioning valve) that controls the input liquid pressure from the master cylinder that exceeds a predetermined value using a pressure receiving area difference and outputs it using a liquid velocity responsive valve and stepped piston, deceleration sensing shutoff valve, etc. The control valve has a spring that biases the stepped piston in the valve opening direction, and a second piston that receives one end of the spring and changes the anchor point of the spring in response to hydraulic pressure. , a pressurizing chamber facing the pressure-receiving surface of the second piston, a check valve controlling the introduction of liquid pressure into the pressurizing chamber, and a check valve compressively interposed between the check valve and the second piston. The device is equipped with a spring that biases the cylinder in the closing direction, and is arranged so that hydraulic pressure is introduced from the master cylinder to the pressurizing chamber via the deceleration sensing shutoff valve and the check valve. It is disclosed in Publication No. 51-2883.

This means that for the device having the control valve and the deceleration sensing shutoff valve, the range of change at the time of control start, that is, the range of change of the bending point of the characteristic curve shown in Figure 2 of the drawings of the present application, is limited to simply replacing the spring. Therefore, the purpose is to enable the control valve to be used over a wider range than before, but the structure of the control valve is complicated, and not only is the length of the control valve long, but also the check valve and the second piston are By changing the spring inserted between the valves, the check valve set pressure changes.If the spring pressure becomes stronger, the durability of the check valve valve piece (seal) will decrease, and if the spring pressure becomes weaker, the durability of the check valve valve piece (seal) will decrease. There is a risk that the seal of the valve piece may be incomplete.

In addition, in order to temporarily absorb the amount of pressure oil generated by the master cylinder, an oil amount absorbing device was installed in the hydraulic line connecting the master cylinder and the relay valve of the booster. 52−
As can be seen in the specification and drawings of No. 44986, the purpose of this is to absorb the pedal stroke that operates the master cylinder, and by closing the ball (valve) of the deceleration sensing valve as described above, the interior of the chamber containing the ball is It does not prevent malfunction of the check valve caused by a sudden increase in oil pressure, and therefore the oil quantity absorption device is simply connected to the master cylinder and the relay valve in series or branched, and the oil absorption device is simply connected to the master cylinder and the relay valve in series or branched. It is not connected, and in this device, it always operates when the master cylinder is operated and only absorbs the pedal stroke, and it operates when the indoor hydraulic pressure suddenly increases due to the closing operation of the ball (valve). isn't it.

The present invention has been devised in view of the above points, particularly for the purpose of stabilizing the operation of the check valve, and will be explained below based on the embodiments shown in the drawings.

In Figure 1, 1 is the brake master cylinder, 2 is the front wheel brake wheel cylinder,
A hydraulic circuit 3 communicates with the master cylinder 1.

A rear brake wheel cylinder 4 is connected to the master cylinder 1 through a hydraulic circuit 5.

Reference numeral 6 denotes a proportioning valve disposed in the hydraulic circuit 5, which is conventionally known, so its details will be omitted.

Reference numeral 7 denotes a control valve which integrally constitutes a deceleration sensing valve 7a and a check valve 7b which are disposed in a control circuit 8 for applying control hydraulic pressure to the proportioning valve 6, and will be specifically described below.

The valve body 71 of the control valve 7 has a ball valve 72B that moves by sensing deceleration, and a cylinder chamber 71a having a conical surface with a predetermined slope toward the pressure oil outlet 71d so as to obtain the set deceleration. A plug 72 having a passage 72a communicating between the cylinder chamber 71a and the control circuit 8 at its right end is fitted to form the deceleration sensing valve 7a.

The valve body 71 also includes a cylinder 71b that communicates with the pressure oil outlet 71e of the cylinder chamber 71a and in which a check valve body 73 having a passage 73a and a valve 73b can move, and a cylinder 71b that is perpendicular to the axial direction of the cylinder 71b. The Prada 7 has a passage 74a forming a valve seat surface 71c and communicating the chamber 71b and the control circuit 8 at the left end of the cylinder 71b.
A spring 75 is disposed between the Prada 74 and the check valve body 73 to push the valve body 73 to the right in the figure and press the valve 73b against the valve seat surface 71c. and constitutes a check valve 7b.

Reference numeral 9 denotes a hydraulic absorption device, which in this embodiment is integrally formed with the control valve main body 71 and includes a case 91 including a cylinder 91a that communicates with the cylinder chamber 71a through a passage 71d, and a piston 92 slidably disposed on the
a piston rod 93 having one end connected to the piston; a plug 94 fitted to the upper end of the case 91 and having a hole through which the rod 93 passes; and a plug 94 disposed between the plug 94 and the piston 92. is,
It is composed of a spring 95 that presses the piston 92 downward in the figure.

Note that the spring 95 of the hydraulic absorption device 9
A spring with a weaker force than the spring 75 of the check valve 7b is used, and the piston 9 is activated by the hydraulic pressure of the pressure oil flowing into the cylinder chamber 71a from the master cylinder 1, which is higher than a predetermined value.
Both springs are adjusted so that the check valve 7b is activated after the check valve 7b is activated.

The present invention is structured as described above, and the following:
Let us describe its effect.

When the master cylinder 1 is actuated, the pressure oil generated in the master cylinder 1 passes through the hydraulic circuit 3 and acts on the wheel cylinder 2 of the front wheel brake, and passes through the hydraulic circuit 5 and the proportioning valve 6 to act on the rear wheel brake. It acts on the wheel cylinder 4 of.

On the other hand, when the pressure oil flowing into the deceleration sensing valve 7a exceeds a predetermined value, it pushes the check valve body 73 open against the force of the spring 75, acts on the proportioning valve 6 through the control circuit 8, and operates the valve. When the vehicle decelerates and the value reaches a predetermined value, the ball valve 72 rolls left and right in the figure along the conical surface to close the pressure oil outlet 71e and cut off the flow of pressure oil. .

At this time, in the device of the present invention, a hydraulic absorption device 9 is provided which communicates with the cylinder chamber 71a of the deceleration sensing valve 7a, which is arranged closer to the master cylinder 1 than the check valve 7b.
Even when the pressure oil outlet 71e and the pressure oil outlet 71e are moved toward the left, and the pressure inside the cylinder chamber 71a rises to a predetermined value or more, the cylinder 91a of the hydraulic absorption device 9 is closed before the check valve 7b is activated. Pressure oil flows into the piston 92, and the piston 92 moves against the force of the spring 95, thereby absorbing sudden oil pressure fluctuations. Therefore, a hydraulic pressure corresponding to the hydraulic pressure generated in the master cylinder 1 is applied to the check valve 7b via the pressure oil outlet 71e, and the proportioning valve 6 is actuated.
Pressurized oil with appropriate oil pressure can be sent to.

As described above, the present device includes a deceleration sensing valve that opens and closes a pressure oil outlet in a cylinder chamber communicating with a master cylinder by movement of a ball valve, and a deceleration sensing valve that communicates with the cylinder chamber and opens and closes the pressure oil outlet in a cylinder chamber when the ball valve is operated in the closing direction. and a hydraulic absorption device that operates when the cylinder chamber hydraulic pressure is equal to or higher than a predetermined pressure, a check valve communicating with the cylinder chamber pressure oil outlet, and proportioning controlled by the pressure oil passing through the deceleration sensing valve and the check valve. By providing a hydraulic absorption device that communicates with the cylinder chamber and operates when the ball valve is operated in the closing direction and when the hydraulic pressure in the cylinder chamber exceeds a predetermined pressure, it is possible to prevent sudden damage, especially when the vehicle is empty. When braking is applied, sudden fluctuations in the oil pressure in the cylinder chamber due to the operation of the ball valve in the closing direction are absorbed by the oil pressure absorption device, thereby stabilizing the operation of the check valve. Therefore, without increasing the set pressure of the check valve, it is possible to cause the check valve to operate in accordance with the operation of the master cylinder during sudden braking when the vehicle is empty, thereby eliminating fluctuations in the proportioning valve operating point. Its operation can be stabilized.

In addition, with the device of the present invention, there is no need to increase the set pressure of the check valve, and therefore the hydraulic loss during loading can be minimized, and a highly safe hydraulic brake device can be obtained, and the set pressure can be increased as much as possible. This increase also has the effect of improving the durability of the check valve.

[Brief explanation of the drawing]

FIG. 1 is an explanatory diagram showing a main part of the hydraulic control system of the present invention cut away, and FIG. 2 is a diagram showing the hydraulic pressure distribution between the front wheels and the rear wheels when the vehicle is loaded and when the vehicle is empty. 1: Master cylinder, 2, 4: Wheel cylinder, 3, 5, 8: Hydraulic circuit, 6: Proportioning valve, 7: Control valve, 7a: Deceleration sensing valve, 7b: Check valve, 71: Valve body, 71
a: cylinder chamber, 71b: cylinder, 71c: seating surface, 71d: passage, 71c: pressure oil outlet, 72: plug, 72a: passage, 72B: ball valve, 73:
Check valve body, 73a: Passage, 73b: Valve, 74: Prada, 74a: Passage, 75: Spring, 9: Hydraulic absorption device, 91: Case, 91
a: cylinder, 92: piston, 93: piston rod, 94: plug, 95: spring.

Claims (1)

[Scope of utility model registration request] a deceleration sensing valve that opens and closes a pressure oil outlet in a cylinder chamber communicating with the master cylinder by movement of a ball valve; A hydraulic absorption device that operates when the above conditions are met;
A brake hydraulic control device comprising a check valve communicating with the cylinder chamber pressure oil outlet, and a proportioning valve controlled by the pressure oil passing through the deceleration sensing valve and the check valve.