Hydraulic circuit for traveling

• US 20030089543A1
• Filed: 12/20/2002
• Published: 05/15/2003
• Est. Priority Date: 10/02/2000
• Status: Active Grant

• Current Assignee: Teijin Seiki Co., Ltd. (Nabtesco Corporation)
• Original Assignee: Teijin Seiki Co., Ltd. (Nabtesco Corporation)
• Inventors: Tanabe, Sadayuki
• Granted Patent: US 6,874,857 B2
• Time in Patent Office: Days
• US Class Current: 180/197
• CPC Class Codes: B60K 17/10 of fluid gearing of fluid clutches B60K17/02
• CPC Class Codes: B60K 28/16 responsive to, or preventing, skidding of wheels brake control systems for vehicle drive stability B60T8/1755; arrangements responsive to a speed condition for adjusting wheel braking force B60T8/32; control of vehicle driving stability otherwise than by controlling the propulsion unit only B60W30/02; preventing wheel slippage by reducing power in rail vehicles B61C15/00
• CPC Class Codes: B60T 13/686 in hydraulic systems or parts thereof
• CPC Class Codes: B60T 2270/203 hydraulic system components
• CPC Class Codes: B60T 8/4809 Traction control, stability control, using both the wheel brakes and other automatic braking systems
• CPC Class Codes: B60W 10/184 with wheel brakes
• CPC Class Codes: F16H 2059/6876 the motor speed
• CPC Class Codes: F16H 2063/3033 the brake is actuated by springs and released by a fluid pressure
• CPC Class Codes: F16H 61/4157 Control of braking, e.g. preventing pump over-speeding when motor acts as a pump
• CPC Class Codes: F16H 61/421 Motor capacity control by electro-hydraulic control means, e.g. using solenoid valves
• CPC Class Codes: F16H 61/44 with more than one pump or motor in operation

Abstract

If a hydraulic motor (23) (traveling wheel (27)) is rotated (or skidding) at high rate, and a hydraulic motor (24) is hardly rotated, a detection controller (68) compares the rotational speeds of both hydraulic motors (23, 24). Then the rotation detected by the rotation detectors (66, 67) to detect the traveling wheel (27) to be skidding, and moves a piston (71) to allow a negative brake (40) to give a braking force to the hydraulic motor (23), and rotate the hydraulic motor (24). In this way, this invention can release the traveling wheel from skidding without the use of a flow dividing valve.

Claims

1. A brake system for a traveling vehicle having at least two traveling wheels driven by a single hydraulic pump through respective hydraulic motors, comprising:

a parking brake for applying braking force to both of the traveling wheels when the hydraulic pump is not driven or the hydraulic pump does not provide sufficient hydraulic pressure to the hydraulic motors; and

an auxiliary brake for applying braking force to only one of the traveling wheels independently of the parking brake.

2. The brake system according to claim 1, wherein

the parking brake includes first pistons for respectively applying the braking force to both of the traveling wheels when the sufficient hydraulic pressure does not act on the first pistons;

and

the auxiliary brake includes second pistons for the respective traveling wheel so that the respective second piston supplies the braking force to the corresponding traveling wheel when a predetermined hydraulic pressure acts on the second piston.

3. The brake system according to claim 2, wherein the first pistons and the second pistons are formed integrally with each other with respect to each traveling wheel.

4. The brake system according to claim 2, wherein the first pistons and the second pistons are formed individually with each other with respect to each traveling wheel.

5. The brake system according to claim 2, wherein

each of the hydraulic motors includes a friction plate connected to a rotational portion for driving the traveling wheel and a stationary counterpart plate connected to a stationary portion thereof for applying the braking force to the rotational portion when the stationary counterpart plate is brought into frictional contact with the rotational friction plate.

6. The brake system according to claim 3, wherein

the rotational friction plate and the stationary counterpart plate are brought into frictional contact with each other by being urged by the first pistons or the second pistons.

7. The brake system according to claim 1 further comprising:

rotation detectors for detecting rotational speeds of the traveling wheels, respectively; and

a computer, connected to the rotation detectors, for comparing the rotational speeds of the traveling wheels,

wherein the computer controls the auxiliary brake based on a result of the comparison.

8. The brake system according to claim 7, wherein

when the computer detects that one of the traveling wheels skids, the auxiliary brake unit applies a braking force to the skidding traveling wheel.