Hydraulic supply arrangement for use with active automotive suspension or the like

• US 5,199,854 A
• Filed: 08/05/1991
• Issued: 04/06/1993
• Est. Priority Date: 08/08/1990
• Status: Expired due to Term

• Current Assignee: Nissan Motor Co., Ltd.
• Original Assignee: Nissan Motor Co., Ltd.
• Inventors: Aoyama, Yutaka
• Primary Examiner(s): Bertsch, Richard A.
• Assistant Examiner(s): Scheuermann, David W.
• Application Number:
  US07/740,384
• Time in Patent Office: 610 Days
• Field of Search: 417/286, 417/287, 417/288, 417/290, 417/292, 417/300, 417/428, 417/282, 280/707, 280/714
• US Class Current: 417/282
• CPC Class Codes: B60G 17/018 characterised by the use of a specific signal treatment or control method
• CPC Class Codes: B60G 17/0408 details, e.g. antifreeze for suspension fluid, pumps, retarding means per se
• CPC Class Codes: B60G 2400/20 Speed
• CPC Class Codes: B60G 2400/38 Speed of engine rotation
• CPC Class Codes: B60G 2400/70 Temperature of vehicle part or in the vehicle

Abstract

The first of two serially arranged electromagnetically operated spool type drain control valves is conditioned to select the drain passage of smaller the pump before the second valve is moved from its closed or communication cut-off position, to its open position wherein hydraulic fluid can be drained therethrough, whereby the spool of the second valve is exposed to a relatively small flow generated force which acts thereon and which tends to move the valve spool toward to its closed position. In another embodiment the hydraulic fluid temperature is monitored and used to modify the control schedule via which the switching of the drain control valves is determined. A further embodiment monitors a parameter which is indicative of the prime mover rotational speed and inhibits the closure of the second of the two valves when the rotational speed is above a predetermined limit.

Claims

1. A source of hydraulic fluid under pressure comprising:

a first pump;

a first supply passage which is associated with said first pump and which receives the discharge thereof;

a first check valve disposed said first supply passage;

a second pump which has a smaller capacity than said first pump;

a second supply passage which is associated with said second pump and which receives the discharge thereof;

a second check valve disposed in said second supply passage;

a first drain passage which leads from said first supply passage at a location between said first pump and said first check valve;

a second drain passage which leads from said second supply passage at a location between said second pump and said second check valve;

drain passage control means for controlling the communication between said first and second drain passages and a reservoir;

said drain passage control means including;

first and second valves, said first valve being connected with said first and second drain passages and said second valve being fluidly interposed between said first valve and a reservoir, said first valve having a first state wherein said first drain passage is open and said second drain passage is cut-off, and a second state wherein said first passage is cut-off and said second drain passage is open,

said second valve having a first state wherein communication between the first valve and the reservoir is permitted and a second position wherein communication between said first valve and the reservoir is cut-off;

valve control means operatively connected with said first and second valves, said valve control means conditioning said first valve to assume its second state before said second valve is switched from its second state to its first state.

2. A source of hydraulic fluid under pressure as claimed in claim 1 wherein said control means controls said first and second valves so that, before either of the first and second valves can be switched in a direction which increases the amount of fluid which is returned to the reservoir, it is maintained in its instant conditions for a predetermined period.

3. A source of hydraulic fluid under pressure comprising:

a first pump;

a second pump, said second pump having a discharge capacity which is less than that of the said first pump;

a first discharge passage into which the first pump discharges its output;

a second discharge passage into which the second pump discharges its output;

a supply conduit which fluidly communicates with the first and second discharge passages;

a first drain passage which communicates with said first discharge passage at a location upstream of a first check valve which is disposed in the first discharge passage at a location upstream of the supply conduit;

a second drain passage which communicates with said second discharge passage at a location upstream of a second check valve which is disposed in the second discharge passage at a location upstream of the supply conduit;

a first spool valve which fluidly communicates with the first and second drain passages, said first spool valve having a first drain port;

a second spool valve fluidly communicated with the discharge port of said first spool valve, said second spool valve having a second drain port;

said first valve having a first spool which can assume a first position in which communication between the first drain passage and the first drain port is established and a second position wherein communication between the second drain passage and the first drain port is established,

said second valve having a second spool which can assume a first position wherein communication between the first and second drain ports is established and a second position wherein communication between the first and second drain ports is cut-off;

hydraulic fluid requirement sensor means;

a temperature sensor for sensing the temperature of the hydraulic fluid; and

control means which is operatively connected with said first and second spool valves for controlling the positions of the first and second spools, said control means including;

means for determining the amount of hydraulic fluid which is required to be supplied into said supply conduit from said first and second pumps, based on the input from said hydraulic fluid requirement sensor means and said temperature sensor; and

means for conditioning the first and second valves in accordance with the determined amount of hydraulic fluid required.

4. A source of hydraulic fluid under pressure as claimed in claim 3 further comprising:

drive means for operatively connecting a prime mover with said first and second pumps; and

means for sensing a rotational speed indicative of the rotational speed of one of the pump and the prime mover;

said control means being responsive to the sensed rotational speed to prevent the second spool from being moved to its second position when the rotational speed is above a predetermined level.

5. A source of hydraulic fluid under pressure as claimed in claim 3 wherein said control means moves the first spool to its second position before moving the second spool of said second spool valve from its second position to its first position.

6. A source of hydraulic fluid under pressure as claimed in claim 5 wherein said control means moves the second spool of said second spool valve from its second position to its first position a predetermined time after moving the spool of the first valve to its second position.

7. A source of hydraulic fluid under pressure comprising:

a first pump;

a second pump, said second pump having a discharge capacity which is less than that of the said first pump;

a first discharge passage into which the first pump discharges its output;

a second discharge passage into which the second pump discharges its output;

a supply conduit which fluidly communicates with the first and second discharge passages;

a first drain passage which communicates with said fist discharge passage at a location upstream of a first check valve which is disposed in the first discharge passage at a location upstream of the supply conduit;

a second drain passage which communicates with said second discharge passage at a location upstream of a second check valve which is disposed in the second discharge passage at a location upstream of the supply conduit;

a first spool valve which fluidly communicates with the first and second drain passages, said first spool valve having a first drain port;

a second spool valve fluidly communicated with the discharge port of said first spool valve, said second spool valve having a second drain port;

said first valve having a first spool which can assume a first position in which communication between the first drain passage and the first drain port is established and a second position wherein communication between the second drain passage and the first drain port is established,

said second valve having a second spool which can assume a first position wherein communication between the first and second drain ports is established and a second position wherein communication between the first and second drain ports is cut-off;

drive means for operatively connecting a prime mover with said first and second pumps; and

means for sensing a rotational speed indicative of the rotational speed of one of the pump and the prime mover;

control means which is responsive to the sensed rotational speed for preventing the second spool from being moved to its second position when the rotational speed is above a predetermined level.