JPH0318299Y2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a hydraulic circuit in an anti-lock brake system.

In general, an anti-lock brake system detects a sign that the wheels of a car are about to lock up when braking in response to a wheel acceleration signal obtained by electrically differentiating the wheel rotational speed from a speed sensor in an electronic control unit, and controls a modulator ( A drive command is given to the hydraulic regulator (hydraulic adjustment device), and the modulator ensures steering stability of the vehicle during braking, and controls the braking force while giving an appropriate wheel slip rate to shorten the braking distance.

In such an anti-lock brake system, when brake pressure from a master cylinder is applied to the primary brake hydraulic chamber of the modulator, the brake pressure is normally transmitted to the secondary brake hydraulic chamber via the cylinder. The brake is operated by the hydraulic output of the secondary brake hydraulic chamber, and when the hydraulic pressure is adjusted by the modulator, the volume of the secondary brake hydraulic chamber is expanded to reduce the brake pressure. . Therefore, unless the secondary brake hydraulic chamber is always filled with brake oil, the hydraulically adjusted brake pressure cannot be accurately transmitted to the brake side.

This idea was created taking the above points into consideration.
The present invention provides a hydraulic circuit for an anti-lock brake system that can reliably fill a secondary brake hydraulic chamber of a modulator with brake oil.

Hereinafter, one embodiment of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 shows an example of the configuration of a hydraulic system in an anti-lock brake system. In response to depression of the brake pedal 1, the primary brake hydraulic pressure chambers 41, 41' of the first modulator 4 are transferred from the tandem master cylinder 2 to the primary brake hydraulic chambers 41, 41' of the first modulator 4. Brake pressure is applied to each of the primary brake hydraulic chambers 51 and 51' in the second modulator 5 through the first modulator 4, respectively, and hydraulic control valves 61 and 51' are respectively applied to the brake pressure.
Brake pressure is applied via 61'. Furthermore, by applying brake pressure to the primary brake hydraulic chambers 41, 41' of the modulator 4, each piston 42, 42'' moves forward, thereby causing the secondary brake hydraulic chambers 43, 4
3', and the right and left front wheel brakes 71, 71' of the automobile are applied in accordance with the respective hydraulic outputs of the secondary brake hydraulic chambers 43, 43'.
are now in operation. Each piston 42, 42' is arranged such that a primary braking hydraulic chamber 41, 42' communicating with the master cylinder 2 is defined at one end side of the partition wall 17, 17' that partitions the cylinders in the modulator 4. ' are fitted, and a secondary brake hydraulic chamber 41, which communicates with the brakes 71, 71', is provided on the other end side of the partition wall 17, 17'.
a second piston 422, such that a second piston 42' is defined;
422' are fitted, and the first and second pistons are connected by rods 18, 18' passing through holes provided in the partition walls 17, 17'. The same applies to the modulator 5 side, and the secondary braking hydraulic chamber 5 is opened by each piston 52, 52' moving forward.
Brake pressure is transmitted to brakes 3 and 53, and the left and right rear wheel brakes 81 and 81' of the automobile are actuated by the respective hydraulic outputs. Further, at the rear portions of the pistons 42, 42' and 52, 52' in the modulators 4 and 5, there are open oil chambers 44, 44' and 54, respectively.
54' are provided, each open oil chamber 44, 44' and 54, between the modulators 4 and 5.
51' are in communication with each other, and the open oil chambers 54, 54' on the modulator 5 side are connected to the master cylinder 2 through the oil passage 9.
It is connected to Reservoir 3. In addition, open oil chamber 4
4, 44' and 54, 54' become larger than the pressure in the secondary brake hydraulic chambers 43, 43' and 53, 53', the release oil chambers 44, 44' and 54, 54' As a means for allowing oil to flow to the secondary brake hydraulic chambers 43, 43' and 53, 53', each release oil chamber 44, 44' and 54, 54' and each secondary brake hydraulic chamber 43, 43' and 53,5
3' and a cup-shaped sealing member 45,
45' and 55,55' are each piston 42,4
2' and 52, 52' side, and each open oil chamber 44, 44' and 54, 5
4' to each secondary brake hydraulic chamber 43, 43' and 5
Oil is supplied to the 3 and 53' sides, but oil is prevented from leaking in the opposite direction.

Further, after the control oil supplied from the reservoir 10 for anti-lock control is pressurized to a predetermined level by the pump 11, the pressure is temporarily accumulated in the accumulator 12, and the accumulated control oil is transferred to the normally closed solenoid valves 131, 132. through each anti-lock control oil chamber 46 of the modulator 4,5.
56, respectively. Furthermore, each anti-lock control oil chamber 46, 5
6 are connected to the reservoir 10 through normally open solenoid valves 141 and 142, respectively. Note that the solenoid valves 131, 132 and 141, 142' are driven to open and close, respectively, according to drive commands from an electronic control unit (not shown), and during anti-lock control, the solenoid valves 131, 132 are opened and closed. and the solenoid valves 141 and 142 are closed.
When not controlled, each solenoid valve 131,
132, 141, and 142 are adapted to return to their normal states.

Therefore, in the anti-lock brake system configured in this way, the primary braking hydraulic chambers 41, 41' and 51 of the modulators 4 and 5 are
51' is applied to each wheel brake 71, 71' by hydraulic output from the secondary brake oil chambers 43, 43' and 53, 53'.
and 81, 81', when an anti-lock drive command is issued from the electronic control section, the control oil (brake (pressurized to a level higher than the pressure) is fed in as appropriate, thereby pushing back the respective pistons 42, 42' and 52, 52', thereby adjusting the brake pressure. At that time, each release oil chamber 44, 44' and 54, 5 in the modulators 4, 5
4', the oil flows back to the reservoir 3 side.

In the hydraulic system of such an anti-lock brake system, especially in the present invention, as shown in FIG.
An orifice 16 is provided in an oil passage 9 connecting between 44' and 54, 54' and the suction portion of the reservoir 3 in the master cylinder 2. Specifically, a part of the outer pipe of the oil passage 9 is squeezed to form the orifice 16.

By providing the orifice 16 in the oil passage 9, it becomes possible to easily ensure that the secondary brake hydraulic chambers 43, 43' of each modulator 4, 5 are filled with control oil. That is, when the brake pedal 1 is released and brake pressure is no longer applied from the master cylinder 2 to the secondary brake hydraulic chambers 43, 43' and 53, 53' of the modulators 4, 5, the pistons 42, 42' and 5
The oil chambers 44, 44' and 54 are opened by the pump action when the oil chambers 2, 52' are returned by the spring force.
54' to each secondary brake hydraulic chamber 43, 43' and 5
3, 53' through cup-shaped seal members 45, 45' and 55, 55',
When each piston 42, 42' and 52, 52' returns to its original position by spring force, each oil chamber 44, 4 is released.
4' and 54, 54' will be pushed back to the reservoir 3 side, and at this time, the orifice 1
6, and as a result, it becomes difficult for the control oil to return to the reservoir 3 side, and the secondary brake hydraulic pressure chamber 43,
43' and 53, 53' can be efficiently filled with control oil. At this time, if the orifice 16 is not provided, the resistance of the oil passage 9 will be small, and the control oil will be easily pushed back to the reservoir 3 side from each release oil chamber 44, 44' and 54, 54'. Accordingly, each release oil chamber 44,
44' and 54, 54' to the secondary brake hydraulic chamber 4
It becomes difficult to supply control oil to 3, 43' and 53, 53'. In addition, modulators 4 and 5
Each release oil chamber 4 is also used when adjusting the brake pressure.
The control oil in 4, 44' and 54, 54' is pushed back to the reservoir 3 side, and at this time it is resisted by the orifice 16, and the pistons 42, 42'
52, 52' become difficult to retreat, but at that time, since a large pressure is applied to the antilock control oil chambers 46, 56, the resistance of the orifice 16 does not interfere with the adjustment of the brake pressure.

In addition, not only during normal operation, but also when piping the oil passage 9 during the manufacturing stage, the brake pedal 1 is depressed and operated many times to release oil while bled air using an air valve appropriately installed in the hydraulic system. The control oil is sent from the chambers 44, 44' and 54, 54' into the secondary brake hydraulic chambers 43, 43' and 53, 53', and in this case, the orifice 16 provided in the oil passage 9 is This action allows the control oil to flow smoothly into the secondary brake hydraulic chambers 43, 43' and 53, 53'.

In addition, if the orifice 16 is not provided at one location in the oil passage 9, but is appropriately provided at multiple locations within the oil passage 9, and the area of each orifice is relatively changed, the effect will be even greater. will be obtained.

In addition, in the configuration shown in FIG. 2, the open oil chambers 44, 44' and 54, 5 of each modulator 4, 5
The reservoir 3 of the master cylinder 2 is disposed above the suction joint at 4', so that even if air is trapped in the oil passage 9, the air will not flow due to its own buoyancy. As a result, the air rises, reaches the reservoir 3 and is released to the outside without being retained in the oil passage 9, and air is naturally vented, and the air in the oil passage 9 flows into the secondary braking hydraulic chamber of the modulator. This is to prevent anything that would reduce the braking force.

As described above, in the hydraulic circuit of the anti-lock brake system according to the present invention, the cylinder of the modulator body is partitioned by a partition wall, and the first piston is fitted into one end of the partition wall to define a primary braking hydraulic chamber communicating with the master cylinder. and a second one on the other end side of the partition wall.
A secondary brake hydraulic chamber is defined in which the piston is fitted and communicated with the brake, and a rod is provided that passes through a hole provided in the partition wall and communicates with the first and second pistons;
An anti-lock control oil chamber is provided on the opposite side of the piston from the primary braking oil pressure chamber and selectively communicates with the control oil pressure source and the reservoir via a switching valve, and on the opposite side from the secondary braking oil pressure chamber of the second piston. A release oil chamber facing the reservoir is provided, and at least one orifice is provided in the oil passage communicating the release oil chamber with the reservoir, and the pressure in the release oil chamber is greater than the pressure in the secondary brake hydraulic pressure chamber. A means is provided to allow oil to flow from the release oil chamber to the secondary brake hydraulic chamber in accordance with the above conditions, thereby ensuring that the secondary brake hydraulic chamber of the modulator is filled with brake oil. This has the excellent advantage that it is possible to effectively prevent air from entering the secondary brake hydraulic chamber and to adjust the brake pressure in the modulator with high precision.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an example of the construction of a hydraulic system in an anti-lock brake system according to the present invention, and FIG. 2 is a diagram showing an embodiment of the hydraulic circuit in an anti-lock brake system according to the present invention. 2...Master cylinder, 3...Reservoir, 4,
5... Modulator, 61, 61''... Hydraulic control valve, 71, 71', 81, 81'... Brake, 1
0... Reservoir, 11 Pressure pump, 12... Accumulator, 131, 132, 141, 142,
... Solenoid valve, 44, 44', 54, 5
4'...Release oil chamber, 9...Oil passage, 16...Orifice.

Claims (1)

[Scope of utility model registration request] The cylinder of the modulator main body 4 is partitioned by a partition wall, a first piston is fitted on one end side of the partition wall to define a primary braking hydraulic chamber 41 communicating with the master cylinder 2, and a second piston is fitted on the other end side of the partition wall. A rod is provided to connect the first and second pistons by passing through a hole provided in the partition wall to define a secondary braking hydraulic chamber 43 which is fitted and communicated with the brake 71, and which connects the first piston to a primary braking hydraulic chamber 43. A switching valve 13 is connected to the control hydraulic power sources 11, 12 and the reservoir 10 on the opposite side from the 41.
1, 141, and a release oil chamber 44 facing the side opposite to the secondary braking oil pressure chamber 43 of the second piston and communicating with the reservoir. At least one orifice is provided in the oil passage communicating with the reservoir, and when the pressure in the release oil chamber 44 becomes higher than the pressure in the secondary brake hydraulic pressure chamber 43, the secondary brake hydraulic pressure is released from the release oil chamber 44. A hydraulic circuit for an anti-lock brake system, characterized in that a means 45 for allowing oil to flow into a chamber 43 is provided.