JPH08192733A - Hydraulic assistor - Google Patents

Abstract

PURPOSE: To provide a hydraulic assistor capable of coping with abrupt braking, ensuring a brake operation in a failure and dispensing with pressure accumulating parts. CONSTITUTION: A hydraulic assistor is composed of a housing 20 provided with a cylinder hole 21, a piston 30 defining an inlet chamber 23 communicating to with master cylinder 71 and an outlet chamber 24 communicating with a brake cylinder 72 in the cylinder hole 21 in the liquid-tight manner, a drive mechanism 40 for giving a thrust to the piston 30, a detecting means 60 for detecting the operational condition of a brake and a control circuit 50 for controlling at least one of the slide position or propelling force of the piston 30 according to a signal of the detecting means 60.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle brake hydraulic booster.

[0002]

2. Description of the Related Art Japanese Unexamined Patent Publication No. 6-56028 discloses a vehicle brake hydraulic pressure booster. This booster brake device is a booster cylinder composed of a booster body and a booster piston that defines a cylinder hydraulic bore of the booster body into a front working hydraulic chamber and a rear relay hydraulic chamber, and a booster cylinder connected to the booster piston. A drive device that applies a forward / backward force, an input port that communicates with the inside of the cylinder hole, an output port that communicates with the working hydraulic chamber, a stroke accumulator that communicates with the relay hydraulic chamber, and the operation of the drive device is controlled. And a control device. When not braking, the booster piston of the booster braking device is retracted, and the input port communicates with the working hydraulic chamber. And
During braking, the control device sends a signal to the drive device via the pedal force sensor, the drive device operates, the booster piston advances, and hydraulic pressure is transmitted to the wheel brakes. At that time, since the input port communicates with the stroke accumulator through the relay hydraulic chamber, a reaction force is applied to the brake depression operation due to the pressure accumulation characteristic of the stroke accumulator, and a good braking feeling is given to the driver. Further, the brake stroke can be freely set by the stroke accumulator regardless of the slide of the booster piston.

[0003]

The problems to be solved by the present invention have the following problems in the above-described brake fluid pressure boosting technique. <a> For the operation of the brake, the brake pedal is depressed, the pedal force sensor detects the pedal force, and the controller drives the drive device with the pedal force signal corresponding to the pedal force signal to advance the booster piston. However, since the input port is opened to the working hydraulic chamber when it is not in operation, and communicates with the relay hydraulic chamber after passing through the piston portion of the booster piston, an operation delay occurs during sudden braking, which is very dangerous. <B> If the boost braking device fails during braking, there is a risk that the brake will not operate. That is, the booster piston moves forward and the input port is open to the relay hydraulic chamber.When the drive device or the control device fails due to a disconnection or the like during brake operation, the booster piston stops moving, so how strongly the brake pedal is applied. Even when the hydraulic pressure in the master cylinder is increased by depressing the pedal, the hydraulic pressure in the working hydraulic chamber is not increased by being absorbed by the stroke accumulator, and the brake pressure is not transmitted to the wheel brakes. <C> A stroke accumulator is required, and liquid leakage from the diaphragm, seal member, and other connecting members of the stroke accumulator is also a concern.

[0004]

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems, and an object thereof is to provide a hydraulic booster as follows. <B> A hydraulic booster with no operation delay during sudden braking. <B> A hydraulic booster that can ensure the brake operation even when the device fails and improve safety. <C> A hydraulic booster that can reduce the number of components. <D> A hydraulic booster that can improve reliability against brake fluid leakage.

[0005]

That is, according to the present invention, the output hydraulic pressure to the brake cylinder is inserted with respect to the input hydraulic pressure from the master cylinder by being inserted in the hydraulic circuit which communicates the master cylinder and the brake cylinder of the vehicle. In a hydraulic booster for amplification, a piston having a housing having a cylinder hole, a piston which is liquid-tightly defined in an inlet chamber communicating with the master cylinder and an outlet chamber communicating with the brake cylinder in the cylinder hole, and the piston. A drive mechanism including a motor that applies a propulsive force to the motor and a mechanism that converts a rotational motion of the motor into a linear motion; a detection unit that detects an operating state of the brake; and a sliding movement of the piston based on a signal from the detection unit. A hydraulic booster comprising a control circuit for controlling at least one of a position and a propulsive force. Further, the present invention is, in the hydraulic booster described above, characterized in that a normally open type electromagnetic valve that is closed when energized is interposed between the inlet chamber and the outlet chamber. It is a device.

[0006]

Embodiment 1 An embodiment of the present invention will be described below with reference to the drawings.

<A> Hydraulic Booster (FIG. 1) FIG. 1 shows a sectional view of a hydraulic booster 10 inserted in the middle of a flow path connecting a master cylinder 71 and a brake cylinder 72. The hydraulic booster 10 includes a housing 20, a piston 30, a drive mechanism 40, a control circuit 50, and a detection means 60.
It is composed of Hereinafter, each part will be described in detail.

<B> Housing (FIG. 1) The housing 20 is provided therein with a cylinder hole 21 and a gear chamber 22 which communicate with each other. The cylinder hole 21 is a hole having a different diameter in which a small diameter portion 211 and a large diameter portion 212 are formed, and the small diameter portion 211 communicates with the gear chamber 22. The inside of the large diameter portion 212 is defined by the flange portion 31 of the piston 30 into an inlet chamber 23 and an outlet chamber 24 on the gear chamber 22 side. The inlet chamber 23 is provided with an inlet port 231 and communicates with the master cylinder 71 via an upstream liquid passage 73.
Further, the outlet chamber 24 is provided with an outlet port 241 and communicates with the brake cylinder 72 via a downstream liquid passage 74.

<C> Piston (FIG. 1) The piston 30 is provided in the cylinder hole 21 of the housing 20.
Are slidably arranged along the hole 21. The piston 30 has a structure in which shaft portions 32 and 33 extend on both sides of a flange portion 31 having an enlarged diameter. The flange portion 31 is provided with a sealing material 311 around the periphery thereof to liquid-tightly define the inlet chamber 23 and the outlet chamber 24, one shaft portion 33 is inserted into the small diameter portion 211, and the other shaft portion 32 is sealed. It penetrates through the retainer 25 and is inserted into the cap 26. A seal 213 is installed between the shaft portion 32 and the seal retainer 25 to prevent leakage of brake fluid in the outlet chamber 24. Also, the shaft portion 3
3 and the small diameter portion 211, a seal material 214 is installed to prevent the brake fluid from leaking into the inlet chamber 23. The shaft core 411 of the driven gear 41 is inserted through the end of the shaft portion 33. On the other hand, the end of the shaft portion 32 on the opposite side has a different shape, which allows the piston 30 to move in the axial direction and prevents the shaft from rotating. For example, as shown in FIG.
Has a flat plate shape, and is fitted and inserted into the groove 261 of the cap 26. The cap 26 is the seal retainer 2
It is non-rotatably attached to the housing 20 via 5. Therefore, the piston 30 can be moved in the axial direction, and the axial rotation thereof can be reliably prevented. It should be noted that the shape of the end of the shaft portion 32 and the shape of the groove 261 of the cap 26 are not limited to the above-mentioned shapes, and other shapes are possible as long as the piston 30 is allowed to move in the axial direction while preventing its axial rotation. May be

<D> Drive Mechanism (FIG. 1) The drive mechanism 40 is composed of a driven gear 41, a drive gear 42 and a motor 43, and the rotational force of the motor 43 is transmitted through the drive gear 42 and the driven gear 41 to the piston 30. It has a structure that is transmitted to and gives a propulsive force. The drive shaft of the motor 43 is arranged in the gear chamber 22 of the housing 20 and has a drive gear 42 attached thereto, and the driven gear 41 is screwed into the drive gear 42. The axis 4 of the driven gear 41
11 is reversibly screwed with the shaft portion 33 of the piston 30. That is, the shaft core 411 and the shaft part 33 are screwed together so that the shaft part 33 is moved in the axial direction by the rotation of the shaft core 411, and the shaft core 411 is rotated by the movement of the shaft part 33 in the axial direction. ing. For screwing the shaft core 411 and the shaft portion 33, for example, a ball screw mechanism or the like can be adopted.

<E> Control Circuit (FIG. 1) The control circuit 50 is a portion that receives a signal from the detection means 60 and outputs a drive signal to the motor 43. Detection means 60
Is a portion that detects the stroke of the brake pedal 75, the pedaling force, the hydraulic pressure of the master cylinder 71, and the like, and outputs a pedaling signal to the control circuit 50 according to the pedaling amount of the pedal 75.

[0012]

Next, the operation of the hydraulic booster 10 will be described.

<A> Normal braking (FIGS. 1 and 2) When the brake pedal 75 is depressed, the master cylinder 71 is pressed.
Is generated in the inlet chamber 23 through the liquid passage 73 and the inlet port 231. On the other hand, the detection means 60
Detects the depression operation of the brake pedal 75 and the amount of depression, and outputs a depression signal to the control circuit 50.
Then, the control circuit 50 receives the depression signal and outputs a drive signal to the motor 43. This drive signal is applied to the motor 4
3 is an electric control signal for instructing the rotating force, the rotating angle, or the rotating speed to the motor 3. Upon receiving the drive signal, the motor 43 starts to drive, the drive gear 42 and the driven gear 41 rotate, and a propulsive force is generated in the piston 30 by the rotational movement of the shaft core 411. As a result, in addition to the increase in the hydraulic pressure in the inlet chamber 23, the propulsive force causes the piston 30 to move toward the outlet chamber 24 side with a boosting action as shown in FIG. Piston 3
The hydraulic power boost ratio of the inlet chamber 23 and the outlet chamber 24, which determines the propulsive force of 0, can be changed only by changing the program of the control circuit 50, and can be easily applied to vehicles with different load capacity and vehicle specifications. Is. Further, since the piston 30 moves according to the depression of the brake pedal 75, the driver can obtain a good feeling of braking without separately mounting a pressure accumulator. Further, by adjusting the cross-sectional area ratio between the inlet chamber 23 and the outlet chamber 24, the brake stroke can be set independently of the boost ratio.

By the movement of the piston 30, hydraulic pressure is transmitted from the outlet chamber 24 to the brake cylinder 72 through the outlet port 241 and the liquid passage 74, and a braking force is applied to the vehicle. As described above, when the brake pedal 75 is depressed, the hydraulic pressure in the inlet chamber 23 rises, and at the same time, the outlet chamber 2
The hydraulic pressure of 4 also rises. At about the same time, the motor 43 and the gears 42, 41 are driven, and the boosted hydraulic pressure is instantaneously transmitted. Therefore, even when sudden braking is applied,
The vehicle can be braked quickly and reliably. The amount of liquid that can flow into the device 10 is preferably equal to or greater than the amount of liquid that can be discharged from the master cylinder 72.

<B> Braking at the time of failure (FIG. 1) The control circuit 50 or the motor 43 becomes inoperable due to a failure such as disconnection of the wiring cord to be connected or no power supply. . However, even in that case, members (control circuit 50,
It is possible to brake the vehicle without going through the motor 43 and the gears 41, 42). That is, when the brake pedal 75 is depressed, hydraulic pressure is generated in the master cylinder 71, and the hydraulic pressure is transmitted into the inlet chamber 23 via the liquid passage 73.
Then, as the hydraulic pressure in the inlet chamber 23 increases, the piston 30
To the outlet chamber 24 side. At that time, the shaft portion 33 of the piston 30 and the shaft core 411 of the driven gear 41 are screwed together by a reversible screw mechanism. Therefore, when a propulsive force acts on the piston 30, the driven gear 41 rotates accordingly and the piston 30 slides. Movement is allowed. Therefore, hydraulic pressure is transmitted from the outlet chamber 24 to the brake cylinder 72 via the liquid passage 74. Therefore, even in the event of a failure, if the brake pedal 75 is depressed, hydraulic pressure is transmitted to the brake cylinder 72, and a boosting action cannot be obtained, but the vehicle can be reliably braked.

[0016]

Second Embodiment In the hydraulic booster 10, the inlet chamber 2
A normally open solenoid valve 80 that closes when energized may be inserted between the valve 3 and the outlet chamber 24. In this case, since the solenoid valve 80 is energized and closed when the device 10 is normally braked, it does not participate in the brake operation, but the device 10 fails and power is not supplied to the control circuit 50. Case or motor 4
When 3 does not function, the energization is released and the valve is opened, and the inlet chamber 2
3 and the outlet chamber 24, that is, the liquid passage 73 and the liquid passage 74 communicate with each other. Therefore, even if the device 10 fails, the hydraulic pressure from the master cylinder 72 is transmitted to the brake cylinder 72 via the electromagnetic valve 80, and the vehicle can be reliably braked. In this embodiment, since the brake operation can be performed without moving the piston 30 when the device 10 fails, the shaft portion 33 of the piston 30 and the shaft core 411 of the driven gear 41 are screwed together by a non-reversible screw mechanism. You may.

[0017]

Third Embodiment In the hydraulic booster 10, the motor 4 is used.
As a mechanism for converting the rotational movement of 3 into a linear movement, a rack mechanism may be used instead of the reversible screw mechanism.

[0018]

Fourth Embodiment In the hydraulic booster 10 of the first or second embodiment, the gears 41 and 42 may be omitted. For example, by engraving a thread groove on the outer peripheral surface of the drive shaft of the motor 43,
If the shaft portion 33 of the piston 30 can be screwed into the shaft portion 33, the motor 43 can directly drive the piston 30.

[0019]

[Fifth Embodiment] In the hydraulic pressure control device 10, in addition to the information of the detection means 60, the piston 3
Information such as 0 position, brake cylinder hydraulic pressure or braking force is input to the control circuit 50, and the control circuit 5 receives the information according to the information.
If 0 is configured to output a drive signal to the motor 43, the control mode of the control circuit 50 can be closed loop.

[0020]

Sixth Embodiment If two hydraulic boosters 10 are used in a vehicle, a two-channel ABS (antilock brake system) can be easily realized. In this case, if it is a front and rear piping vehicle, the control valve becomes unnecessary. It can also be applied to traction control and automatic braking.

[0021]

Since the present invention is as described above, the following effects can be obtained. <B> When the hydraulic pressure in the inlet chamber communicating with the master cylinder rises, the piston moves accordingly to the outlet chamber side, and the braking pressure is doubled and transmitted. Therefore, there is no operation delay even during sudden braking, and vehicle safety can be ensured. <B> Even if the motor or the control circuit fails due to a disconnection or the like during operation of the brake, the boosting action disappears, but a braking force corresponding to the pedal effort of the brake pedal is obtained. Therefore, it is possible to improve safety without causing a dangerous state such as inability to operate the brake. <C> If a normally open solenoid valve mechanism that closes when energized is inserted between the fluid passages that connect the inlet chamber and the outlet chamber, the inlet chamber and outlet chamber communicate with each other in the event of a failure to ensure a braking force. Therefore, a double safety structure is obtained. <D> Accumulators and other pressure accumulating members are not required, and the number of component parts can be reduced. In addition, it is possible to reduce locations where liquid leakage is concerned, and improve reliability against brake fluid leakage.

[Brief description of drawings]

FIG. 1 is an explanatory diagram of a hydraulic booster.

FIG. 2 is an explanatory diagram when braking.

FIG. 3 is an explanatory diagram of a solenoid valve according to a second embodiment.

Claims (2)

[Claims] 1. A hydraulic booster for inserting a master cylinder and a brake cylinder of a vehicle into a hydraulic circuit that communicates with each other, for amplifying an output hydraulic pressure to a brake cylinder with respect to an input hydraulic pressure from the master cylinder, A housing that has a cylinder hole, a piston that liquid-tightly defines an inlet chamber that communicates with the master cylinder and an outlet chamber that communicates with the brake cylinder in the cylinder hole, and a motor and a motor that apply propulsive force to this piston. A drive mechanism having a mechanism for converting rotational movement into linear movement, detection means for detecting the operating state of the brake, and at least one of the sliding position of the piston or the propulsive force based on the signal of the detection means. A control circuit for controlling,
A hydraulic booster characterized by being composed of. 2. The hydraulic booster according to claim 1, wherein a normally open solenoid valve that closes when energized is inserted between the inlet chamber and the outlet chamber. Pressure booster.