US 5,330,258 A · Pressure control unit for brake system

A pressure control unit for a brake system that includes a master cylinder connected to brake circuits for a plurality of drive and follower wheels, each brake circuit being connected to a wheel cylinder through a main brake line, and each brake circuit includes a normally open-type inlet valve installed in the main brake line to open or close passage to the main brake line, a normally closed-type outlet valve to open or close passage between the wheel cylinder and a working fluid reservoir, a suction line that connects a suction side of a hydraulic pump connected to the working fluid reservoir, and a delivery line that connects the hydraulic pump to the main brake line on a master cylinder side from the outlet valve, the pressure control unit for the drive wheels comprising:

(a) a selector valve, fitted in the main brake line on the master cylinder side of a connection between the main brake line and the delivery line, said selector valve being formed to switch to a closed state only during traction control operation;
(b) a reflux line which connects a master cylinder reservoir and the suction line;
(c) a switching valve installed in said reflux line, said switching valve being formed to switch to a free passage state between the master cylinder reservoir and the suction line during traction control operation;
(d) a relief valve, fitted across both the main brake line and said reflux line, wherein a first end of said relief valve is subject to pressure from the master cylinder, and a second end is subject to pressure from the delivery line,
during traction control operation, when the pressure from the delivery line reaches or exceeds a threshold level, said relief valve opens to exhaust excess hydraulic pressure of the delivery line to said reflux line, and at all other times said relief valve remains closed;
and
(e) a check valve connected to the suction line on a working fluid reservoir side of a connection with said reflux line.

4 more elements

A pressure control unit for a brake system connected to an antilock brake circuit and a traction control system, the brake system including a master cylinder connected to brake circuits for a plurality of drive and follower wheels, each brake circuit being connected to a wheel cylinder through a main brake line, and each brake circuit includes a normally open-type inlet valve installed in the main brake line to open or close passage to the main brake line, a normally closed-type outlet valve to open or close passage between the wheel cylinder and a working fluid reservoir, a suction line that connects a suction side of a hydraulic pump connected to the working fluid reservoir, and a delivery line that connects the hydraulic pump to the main brake line on a master cylinder side from the outlet valve, the pressure control unit for the drive wheels comprising:

(a) a selector valve, fitted in the main brake line on the master cylinder side of a connection of the main brake line and the delivery line, said selector valve being formed to switch to a closed state only during traction control operation;
(b) a reflux line which connects the master cylinder reservoir and the suction line;
(c) a pressure-actuated switching valve connected across both the main brake line and said reflux line, wherein said switching valve in all situations allows free passage through the main brake line, but during non-braking or normal braking periods, and during operation of the antilock brake circuit, said switching valve closes the reflux line, and during operation of the traction control system, when pressure of the delivery line reaches or exceeds a threshold value, said switching valve opens said reflux line to enable free passage between the suction line and the master cylinder reservoir via the said reflux line;
(d) a relief valve, fitted across both the main brake line and said reflux line, wherein a first end of said relief valve is subject to pressure from the master cylinder, and a second end is subject to pressure from the delivery line,
during traction control operation, when the pressure from the delivery line reaches or exceeds a threshold level, said relief valve opens to exhaust excess hydraulic pressure of the delivery line to said reflux line, and at all other times said relief valve remains closed;
(e) a first check valve connected to the suction line on a working fluid reservoir side of a connection with said reflux line;
and
(f) a second check valve connected to the delivery line which links the hydraulic pump and the main brake line, and which permits flow only from the delivery line to the main brake line.

5 more elements

A pressure control unit for a brake system connected to an antilock brake circuit and a traction control system, the brake system including a master cylinder connected to brake circuits for a plurality of drive and follower wheels, each brake circuit being connected to a wheel cylinder through a main brake line, and each brake circuit includes a normally open-type inlet valve installed in the main brake line to open or close passage to the main brake line, a normally closed-type outlet valve to open or close passage between the wheel cylinder and a working fluid reservoir, a suction line that connects a suction side of a hydraulic pump connected to the working fluid reservoir, and a delivery line that connects the hydraulic pump to the main brake line on a master cylinder side from the outlet valve, the pressure control unit for the drive wheels comprising:

(a) a selector valve, fitted in the main brake line on the master cylinder side of a connection of the main brake line and the delivery line, said selector valve being formed to switch to a closed state only during traction control operation;
(b) a reflux line which connects a master cylinder reservoir and the suction line;
(c) a pressure-actuated switching valve fitted across both the main brake line and said reflux line, wherein said switching valve in any braking or traction situation allows free passage through the main brake line and during non-braking periods and during traction control operation, said switching valve opens passage through said reflux line but during normal braking periods or during operation of the antilock brake circuit, said switching valve closes said reflux line;
(d) a pressure-controlled relief valve, fitted across both the main brake line and said reflux line, wherein a first end of said relief valve is subject to pressure of the master cylinder, and a second end is subject to pressure of the delivery line, and during traction control operation, when the pressure from the delivery line reaches or exceeds a threshold level, said relief valve opens to exhaust excess hydraulic pressure of the delivery line to said reflux line, and at all other times said relief valve remains closed;
and
(e) a check valve fitted in the suction line on a working fluid reservoir side of a connection with said reflux line.

3 more elements

A pressure control unit for a brake system connected to an antilock brake circuit and a traction control system, the brake system including a master cylinder connected to brake circuits for a plurality of drive and follower wheels, each brake circuit being connected to a wheel cylinder through a main brake line, and each brake circuit includes a normally open-type inlet valve installed in the main brake line to open or close passage to the main brake line, a normally closed-type outlet valve to open or close passage between the wheel cylinder and a working fluid reservoir, a suction line that connects a suction side of a hydraulic pump connected to the working fluid reservoir, and a delivery line that connects the hydraulic pump to the main brake line on a master cylinder side from the outlet valve, the pressure control unit for the drive wheels comprising:

(a) a selector valve, fitted in the main brake line on the master cylinder side of a connection of the main brake line and the delivery line, said selector valve being formed to switch to a closed state only during traction control operation;
(b) a reflux line which connects a master cylinder reservoir and the suction line;
(c) a pressure-actuated switching and relief valve unit fitted across both the main brake line and said reflux line and connected to the delivery line, wherein said valve unit in any braking or traction situation allows free passage through the main brake line and during non-braking periods and during traction control operation, said valve unit opens passage through said reflux line but during normal braking periods or during operation of the antilock brake circuit, said valve unit closes said reflux line, and
during traction control operation, when the pressure from the delivery line reaches or exceeds a threshold level, said relief valve opens to exhaust excess hydraulic pressure of the delivery line to said reflux line, and at all other times said relief valve remains closed;
and
(e) a check valve fitted in the suction line on a working fluid reservoir side of a connection with said reflux line.

3 more elements

Pressure control unit for brake system

Life of this patent

Pressure control unit for brake system

Life of this patent

Abstract

Claims18