Flow control device of power steering apparatus

• US 6,041,807 A
• Filed: 04/09/1998
• Issued: 03/28/2000
• Est. Priority Date: 04/09/1997
• Status: Expired due to Fees

• Current Assignee: Toyoda Koki Kabushiki Kaisha (Toyota Motor Corporation)
• Original Assignee: Toyoda Koki Kabushiki Kaisha (Toyota Motor Corporation)
• Inventors: Watanabe, Kazuhiro, Kato, Hideya, Imanishi, Takashi, Fujiwara, Hidetoshi, Honaga, Susumu, Inaguma, Yoshiharu
• Primary Examiner(s): Hepperle, Stephen M.
• Application Number:
  US09/057,550
• Time in Patent Office: 719 Days
• Field of Search: 137/115.01, 137/115.02, 137/115.03, 137/115.04, 137/115.05, 137/115.06, 137/115.19, 137/549
• US Class Current: 137/115.05
• CPC Class Codes: B62D 5/062 Details, component parts
• CPC Class Codes: F15B 11/042 by means in the feed line , i.e. "meter in"F15B11/046, F15B11/05 take precedence
• CPC Class Codes: F15B 11/0423 by controlling pump output or bypass, other than to maintain constant speed
• CPC Class Codes: F15B 11/05 specially adapted to maintain constant speed, e.g. pressure-compensated, load-responsive F15B11/161 takes precedence
• CPC Class Codes: F15B 2013/008 Throttling member profiles
• CPC Class Codes: F15B 2211/2053 Type of pump
• CPC Class Codes: F15B 2211/40515 with variable throttles or orifices
• CPC Class Codes: F15B 2211/40561 the pressure compensating valve arranged upstream of the flow control means
• CPC Class Codes: F15B 2211/45 Control of bleed-off flow, e.g. control of bypass flow to the return line
• CPC Class Codes: F15B 2211/455 Control of flow in the feed line, i.e. meter-in control
• CPC Class Codes: F15B 2211/50509 the pressure control means controlling a pressure upstream of the pressure control means
• CPC Class Codes: Y10T 137/2584 Relief or bypass closes as main opens
• CPC Class Codes: Y10T 137/2589 Pilot valve operated
• CPC Class Codes: Y10T 137/2625 Pilot valve
• CPC Class Codes: Y10T 137/8085 Hollow strainer, fluid inlet and outlet perpendicular to each other

Abstract

A flow control device, responsive to the rotational speed of a pump and to load pressure, has a simple structure. And a housing of the flow control device for saving energy can make use of a general pump housing not for saving energy as a common housing.

The flow control device of a power steering apparatus, arranged in a housing of a pump, includes a flow control valve and a load pressure responsive valve. The flow control valve includes a bypass spool with a control rod penetrating a metering orifice. The load pressure responsive valve is incorporated in a union for response to the load pressure. The control rod is located on the bypass spool for response to the rotational speed of the pump.

Claims

1. A flow control device of a power steering apparatus comprising:

a valve receiving bore formed in a housing of a pump and connecting to a supply passage leading operating fluid discharged from said pump;

a union, arranged in said valve receiving bore, having a union bore connecting to said valve receiving bore;

a metering orifice arranged in said union bore;

a flow control valve, arranged in said valve receiving bore, having a spring chamber and a bypass spool for regulating an opening area of a bypass passage in accordance with pressure difference across said metering orifice,

said spring chamber connected to a downstream side of said metering orifice in said union bore and connected to a reservoir,

said bypass spool urged by a spring in said spring chamber, said bypass spool having a control rod penetrating said metering orifice for regulating an opening area of said metering orifice in accordance with a movement of said bypass spool; and

a load pressure responsive valve, arranged in said union, for regulating communication between said spring chamber and said reservoir in response to a rise of load pressure of the operating fluid.

2. The flow control device of a power steering apparatus according to claim 1, further comprising a control valve having variable throttles arranged on paths connected to said pump, both fluid chambers of a power cylinder and said reservoir.

3. The flow control device of a power steering apparatus according to claim 1, wherein said control rod of said bypass spool has a small diameter portion, a taper portion and a large diameter portion.

4. The flow control device of a power steering apparatus according to claim 1, wherein said union bore has an outlet port for leading the operating fluid passed through said metering orifice, and a load pressure responsive spool of said load pressure responsive valve arranged between said outlet port and said metering orifice.

5. The flow control device of a power steering apparatus according to claim 4, wherein said load pressure responsive spool is urged by a spring toward said outlet port.

6. The flow control device of a power steering apparatus according to claim 4, wherein said load pressure responsive spool is urged by a spring toward said metering orifice.

7. The flow control device of a power steering apparatus according to claim 4, wherein said load pressure responsive spool has a filter member for filtering the operating fluid to remove foreign substance.

8. The flow control device of a power steering apparatus according to claim 7, wherein said filter member forms a leading path between an inner surface of said load pressure responsive spool and an out er surface of said filter member, said leading path decreasing in area downstream.

9. The flow control device of a power steering apparatus according to claim 4, wherein said load pressure responsive valve has a notch formed an outer surface of said load pressure responsive spool, and said load pressure responsive valve regulates the communication between said spring chamber and said reservoir through said notch.