JPS61125957A - Hydraulic booster with fail safe device - Google Patents

Abstract

PURPOSE:To enable a device to be miniaturized by providing a hydraulic booster with a fail safe mechanism so as to compensate for a possible pressure loss in a hydraulic pressure accumulating system allowing a braking force to be secured. CONSTITUTION:A cylinder 1 includes No.3 cylinder which contains a master cylinder mechanism, No.1 cylinder in a shoulder form which contains a pressure control mechanism, and No.2 cylinder which contains an oil pressure generating mechanism including a power piston. The power piston 16 receives hydraulic piston 17 with a force for displacement. The hydraulic piston 17 includes a shut-off valve 18 which is contained in an oil passage 17a. The shut-off valve usually keeps its ball 20 spaced apart from its valve seat 17b allowing the oil passage to be opened. But when the piston 17 is displaced, as an engagement by an engaging stem 19 is released, the ball 20 is allowed to seat on the valve seat 17b permitting the oil passage 17a to be closed.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Application of the Invention] The present invention relates to a hydro booster for a brake system, and more specifically to a hydro booster equipped with a seven-function safety mechanism that can generate brake hydraulic pressure even when a pressure accumulation source fails. It concerns boosters.

[Background of the invention]

Traditionally, a hydrobooster has been used as a booster mechanism as one of the devices used in the brake system for vehicle braking.
This is a system in which large hydraulic pressure from a pressure accumulation source is transmitted to the brake hydraulic pressure generating mechanism while controlling the hydraulic pressure transmission level, and the degree of opening of the so-called dart can be controlled by a relatively small input (lower layer) to the brake pedal, etc. The hydraulic pressure transmission level is determined by determining the hydraulic pressure transmission level.

By the way, when it comes to vehicle brake systems, it has recently become important to consider the idea of compensation, or so-called fail-safe, to ensure braking force even in the event of oil pressure failure for some reason. As such, it is desired that even in the above-mentioned hydro booster, measures against oil pressure failure of the pressure accumulation source are provided.

[Purpose of the invention]

From this point of view, the present invention improves the structure of the hydro booster, and normally functions as a hydro booster, but
The purpose of the present invention is to provide a hydro booster equipped with a fail-safe mechanism that can function as a general master cylinder hydraulic pressure generation mechanism when a hydraulic pressure failure occurs in the pressure accumulation source of the hydro booster system.

[Summary of the invention]

The gist of the present invention, which has been made to achieve such an object, is to provide a brake hydraulic pressure generation mechanism including a power piston that is moved by hydraulic pressure transmission from a pressure accumulation source and generates brake hydraulic pressure in an output oil chamber; A hydraulic control mechanism including a valve piston that moves further to determine the hydraulic pressure level transmitted from the pressure accumulation source to the brake hydraulic generation mechanism, and
) A master cylinder mechanism that generates f rake hydraulic pressure, and the hydraulic control mechanism is provided to return a depression reaction force proportional to the transmitted hydraulic pressure level to the brake pedal, and the depression reaction force causes the valve piston to be activated by the depression reaction force. The brake hydraulic pressure generating mechanism is provided with a communication path between the hydraulic pressure generating chamber of the master cylinder mechanism and the output oil chamber, and a hydraulic pressure generating mechanism configured to control movement of the brake hydraulic pressure to below the predetermined amount. The present invention provides a fail-safe hydro booster, characterized in that it is provided with a cutoff valve that closes the communication passage.

[Embodiments of the invention]

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

This embodiment shows a case in which the vehicle is constructed as a hydro booster with an anti-skid device, and the vehicle brake system is constructed as two independent systems (however, only one system is shown in the drawing). In FIG. 1, 1 is a cylinder body, which includes a first cylinder housing a master cylinder mechanism, a stepped first cylinder housing a pressure control mechanism, and a first cylinder housing a brake hydraulic pressure generation mechanism including a power piston. are provided for each.

First, the structure of the first cylinder part will be explained. This is a pulp screw inserted into the small diameter cylinder part from the opening at one end of the cylinder body 1. : A push rod 2 and a control piston 3 fitted on the outer periphery of the inner end of the push rod 2 and fitted inside the large diameter cylinder are housed. Through the cooperation of the rod 2 and the control piston 3, brake oil (described later) is discharged from the brake mulrator 4, which is a pressure accumulation source, in response to the pressing force on a brake pedal (not shown) connected to the outer end of the push rod 2. A pressure control valve is configured to determine the hydraulic pressure level communicated to the generating mechanism.

That is, the control piston 3 has a radial passage 3a that guides the pressure oil from the accumulator 4 to the inner cylinder circumferential surface where the inner end of the push rod 2 is fitted, and the push rod 2 has a A radial passage 2& that opens on the inner cylinder peripheral surface of the control piston 3 is provided, and these bidirectional radial passages 2&.

3& are in a non-communicating state where they do not face each other as shown in the figure under normal conditions (when not braking), but when the push rod 2 moves relative to the control piston 3 due to the foot of the pedal during play (during f rake). moves to the opposing position and becomes a communicating position with the radial passage 2ae3a, and the accumulator 4
Pressure oil from the push rod 2 is transmitted to the radial passage 2a of the push rod 2.

The radial passage of the push rod 2 is outputted downstream via the longitudinal passage 2b in the shaft center and through the stepped oil chamber E in the small diameter cylinder section, and the oil pressure in the stepped oil chamber E is The action acts in the opposite direction to the push-in of the bushing rod 2, giving a depression reaction force to the brake pedal.

The control piston 3 is biased to the initial position shown in the figure by a lightly loaded return spring 5 stretched between the inner wall of the cylinder body, and the bushing rod 2 is biased to the first cylinder position by a return spring of a brake pedal (not shown). For external extraction, a spring force is applied in the extraction direction.

Reference numeral 6 denotes a locking ring that defines the limit of the extension of this push rod r2.

Furthermore, the gumshield rod 2 and the control piston 3 are provided with radial passages 2c and 3b for pressure release, which normally communicate with each other, but which release the communication relationship during braking. When the brake is released, the hydraulic pressure in the stepped oil chamber E is released to a reservoir side, which will be described later, via a release oil chamber.

As described above, the pressure control mechanism housed in the No. 1 cylinder shuts off the pressure oil from the akimulator 4 when not braking, releases the hydraulic pressure in the stepped oil chamber E, and when braking. While blocking pressure release in the stepped oil chamber E, hydraulic pressure corresponding to the degree of under-road pressure is transmitted to the stepped oil chamber EIC to the brake pedal.

Next, to explain the master cylinder mechanism housed in the No. 1 cylinder, the master cylinder mechanism in this example is of a two-system type (tandem type), and therefore functions essentially as one body with the control piston 2 described above. The first piston 7 has a first piston 7 and a second piston 8 arranged in pair with the first piston 7, and when the first and second pistons 7. Each of them is designed to independently generate the same hydraulic pressure.

The master cylinder device including the first piston 7 and the second piston 8 is structurally similar to a general tandem type master cylinder, and functionally, as described above, it functions as a fail-safe mechanism. It is something that works.

In other words, when the first piston 7 receives an external force and moves in the square direction in the figure, the seal 9 closes the compensating port 10 to generate oil pressure in the oil chamber A, and at the same time, the second piston 8 is moved and As a result, hydraulic pressure is generated in the oil chamber F. Na-
In the figure, 11 is an intake port), 12.13 is a return spring, and 14 and 14' are reservoirs connected through the respective oil chambers A, yK--) 10.11.

And the oil chamber A by such a master cylinder mechanism,
The oil chamber is generated at F when the aforementioned sticky rod 2 directly presses the first piston 7 via the control piston 3. Therefore, since this is a measure against failure of the accumulator 4 system, in this example, the control piston 3 is directly suppressed by the bushing rod 2, and the bushing rod 2 beyond the stroke range to function as a pressure control valve is During the movement, the shoulder 2d of the bushing rod 2 engages with the control piston 3, and normally, the shoulder 2d of the bushy rod 2 and the control piston 3 are caused by the reaction force of stepping on the bushing rod 2 in the oil chamber E. The oil chambers A and E do not generate hydraulic pressure.

Next, to explain the brake hydraulic pressure generating mechanism housed in the No. 1 cylinder, in this example, a power piston 16 is used to generate brake hydraulic pressure during normal braking, and a brake hydraulic pressure generating mechanism is used in cooperation with the power piston 16 during normal braking. It consists of a combination of a hydraulic piston 17 that generates hydraulic pressure and incorporates a normally open shutoff valve 18 that transmits the hydraulic pressure generated in the oil chamber A of the master cylinder device to the brake device side in the event of a failure.

The power piston 16 moves in response to the oil pressure in the oil chamber C to which pressure oil is transmitted from the oil chamber E through an anti-skid device consisting of an electromagnetic valve mechanism, and applies a moving force to the hydraulic piston 17. ing. On the other hand, hydraulic vist/1
7 has a flow path 17m penetrating in the axial direction, and has a locking rod 19
Normally, the gale 20 is separated from the valve seat 17b by contact with the valve seat 17b to open the flow path 17m, and the hydraulic piston 17
A check valve-type cutoff valve 18 is built in the flow path 17a, and when the locking rod 19 is disengaged and the lever 20 is seated on the valve seat 17b, the check valve type shutoff valve 18 closes the flow path 17a. ing.

The oil chamber A' facing the knocker piston side end of the hydraulic piston 17 communicates with the oil chamber A of the master cylinder device, and the output oil chamber B facing the opposite end of the hydraulic piston 17 communicates with the wheel cylinder of the brake device. It is clearly communicated.

As described above, when the hydraulic pressure is transmitted to the oil chamber C, the knocker piston 16 moves and presses the hydraulic piston 17, which closes the shutoff valve 18 and thereafter the output oil chamber B receives the hydraulic pressure of the oil chamber C. Brake oil pressure is generated proportional to.

On the other hand, when hydraulic pressure is not transmitted to the oil chamber C during braking due to failure of the achievator 4, etc., hydraulic pressure is generated in the oil chamber A of the master cylinder device as described above, and at this time, the hydraulic piston 17 does not move, so the shutoff valve 18 remains open, the oil pressure generated in the oil chamber A is transmitted to the output oil chamber B through the oil chamber, and this becomes the brake oil pressure.

FIGS. 2(a) to 2) are enlarged views of a specific configuration for shifting the cutoff valve 18 in the hydraulic piston from the open state to the closed state, and show the detailed structure of the shutoff valve 18 in the hydraulic piston described above. The tip of the hydraulic piston 17 is connected to the hydraulic piston 17 via the spacer 21.
The locking rods 19 of the spacer 21 are spaced apart by a gap t during non-braking, so that only the hydraulic piston 17 moves during this gap t. The shutoff valve 18 is opened and then closed.

Next, the anti-skid device will be briefly explained.

The anti-skid device 23 in this example uses a normally open solenoid valve NO installed in the middle of a path for transmitting oil pressure from an oil chamber E to an oil chamber C, and transmits oil pressure in an oil chamber C (via an oil iD) to a reservoir 1.
It consists of a pair of normally closed solenoid valves NC that are released at
These two solenoid valves NO.

The NC can select, for example, the modes shown in Table 1 below using an anti-skid signal from an anti-skid control circuit (not shown).

Table f This kind of mode selection is based on a known anti-skid control circuit that outputs a brake pressure reduction signal, a hold signal, and a repressurization signal depending on the rotational state of the wheels. do it.

Note that 24 is a pump that pumps pressure oil from the release system (oil chamber D) to the achievator 4.

The operation of the hydrobooster with anti-skid device having the above structure will be summarized and explained.

During normal braking, by pressing the push rod 2 from the fV key pedal,
The pressure control valve functions to transmit oil pressure to the oil chamber E, and the push rod 2 generates a reaction force for pushing down. Further, the oil pressure in the oil chamber E is transmitted to the oil chamber C, causing movement of the arm piston 16. Therefore, the opening/closing valve 18 of the brake hydraulic pressure generating mechanism is closed, and the movement of the hydraulic piston 17 generates brake hydraulic pressure in the output oil chamber B.

This brake oil pressure is determined by the oil pressure in the oil chamber C, and therefore by the value of the oil pressure transmitted to the oil chamber E controlled by the pressure control valve.

Note that at this time, no oil pressure is generated in the oil chambers A and A'.

Pressure control is performed by the push rod 2 to the extent that the seal 9 does not close the compensating port 10.

During fail-safe mode, when pressure accumulation does not occur due to failure of the achiever 4, etc., the hydraulic pressure in the oil chamber KK is not transmitted even if the brake 4 is under the brake pedal. The push rod 2 is thus moved until it engages the control piston 3, which is directly pressed by the push rod 2.

Therefore, oil pressure is generated in oil chambers A and F, and the oil pressure in oil chamber A is transmitted to oil chamber A' of the brake oil pressure generation mechanism. At this time, since the power piston 16 is not moving, the shutoff valve 18 continues to be open, and therefore the oil chamber A −+
The oil pressure at A' is directly transmitted to the output oil chamber B and becomes brake oil pressure.

When a sudden drop in wheel rotation occurs during normal braking during anti-skid control, an anti-skid signal (not shown) first closes solenoid valve NO, stops any further increase in oil pressure in oil chamber C, and at the same time opens solenoid valve NC. Ru.

Therefore, the oil pressure in the oil chamber C is reduced, and the power piston 1
6 becomes smaller, the brake oil pressure generated in the oil chamber B is reduced, and the braking force of the wheels becomes smaller (see the beginning of Table 1).

If the rotational speed of the wheel is recovered by this, the solenoid valve NC
(see C in Table 1), and then open solenoid valve NO as necessary (see B in Table 1), the hydraulic pressure is transmitted to the oil chamber C and the brake hydraulic pressure (output oil chamber B) is reapplied. Pressure is applied.

Note that since the hydraulic pressure reduction and the like at this time occur only downstream of the solenoid valve NO, there is virtually no pressure fluctuation on the oil chamber E side, and the influence on the fluctuation of the depression reaction force of the brake pedal is minimal.

According to the hydro booster with anti-skid device having the configuration of this embodiment described above, the hydraulic system (E, C, D) for normal brake operation and the hydraulic system for fail-safe are independent. , air bubbles, etc., the various mechanisms for anti-skid control are shared with the various mechanisms for the booster, which is effective in reducing the overall size. Since the mechanism is a hydraulic system separate from the anti-skid system,
There is an advantage that safety can be better ensured.

〔Effect of the invention〕

As described above, according to the fail-safe hydrobooster of the present invention, braking force is ensured even in the event of oil pressure failure in the pressure accumulation source system. Although the hydraulic systems used are independent, their usefulness is extremely great, as the hydraulic pressure generation mechanism can be conveniently used in combination, making the device more compact. be.

[Brief explanation of drawings]

Figure 1 is a schematic cross-sectional view of a hydro booster according to the present invention, and Figures 2 (a), (b), f, and 2) are views of the on-off valve.
1. It is a diagram for explaining the structure. 1 Niji cylinder is D, 2: Push rod (valve piston), 3: Control piston, 4: Akinimulator, 5: Return spring, 6: Locking ring, 7: First piston, 8: Second
Piston, 9: Piston cut, 10: Carp 4-seating port, 11: Intake port, 12.13: Return spring, 14.14', 15: Reservoir, 16: /'''7-piston, 17 2-hydraulic piston, 18
: Shutoff valve, 19: Locking rod, 20: ? - Le,
21 Ni spacer, 22: Spring, 23: Anti-skid device, 24: Pump.

Claims (1)

[Claims] A brake hydraulic pressure generation mechanism including a power piston that moves by hydraulic pressure transmission from a pressure accumulation source to generate brake hydraulic pressure in an output oil chamber, and a hydraulic pressure level that moves when the brake pedal is depressed and is transmitted from the pressure accumulation source to the brake hydraulic pressure generation mechanism. The hydraulic control mechanism includes a hydraulic control mechanism including a valve piston that determines the transmission pressure level, and a master cylinder mechanism that generates brake hydraulic pressure by moving the valve piston by a certain amount or more, and the hydraulic control mechanism generates a depression reaction force proportional to the transmitted hydraulic pressure level. is provided so as to return to the brake pedal, and the movement of the valve piston is regulated to below the predetermined amount by the depression reaction force. A hydro booster with a fail-safe system, comprising a communication path between the chamber and the output oil chamber, and a shutoff valve that closes the communication path when the power piston moves.