Active vehicle suspension with a hydraulic spring

• US 6,834,736 B2
• Filed: 12/17/2002
• Issued: 12/28/2004
• Est. Priority Date: 12/17/2002
• Status: Expired due to Fees

• Current Assignee: Husco International Incorporated
• Original Assignee: Husco International Incorporated
• Inventors: Griesbach, Eric Norman, Kramer, Bradley James, Rogala, Jeffrey A.
• Primary Examiner(s): Dickson, Paul N.
• Assistant Examiner(s): To, Toan C
• Application Number:
  US10/321,325
• Publication Number:
  US 20040112659A1
• Time in Patent Office: 742 Days
• Field of Search: 180/89.12, 280/124.157, 280/124.158, 280/124.159, 280/124.16, 280/5.507
• US Class Current: 180/89.12
• CPC Class Codes: B60G 11/265 hydraulic springs
• CPC Class Codes: B60G 17/015 the regulating means comprising electric or electronic elements B60G17/002, B60G17/005 take precedence
• CPC Class Codes: B60G 2300/082 Tractors
• CPC Class Codes: B60G 99/002 Suspension details of the suspension of the vehicle body on the vehicle chassis
• CPC Class Codes: B60N 2/527 using liquids
• CPC Class Codes: B62D 33/0608 pneumatic or hydraulic suspension

Abstract

A suspension system isolates the operator cab or seat from vibrations in the chassis of a vehicle. At least one hydraulic actuator is connected between the cab or seat and the vehicle chassis. An accumulator is coupled to the hydraulic actuator and acts as a hydraulic spring to attenuate high frequency vibrations. An electrically operable, three-position, closed-center control valve selectively connects the hydraulic actuator to a source of pressurized hydraulic fluid or a reservoir. Sensors detect acceleration and displacement of the cab or seat to which a controller responds by operating the valve. That control of the valve actively drives the hydraulic actuator to produce motion that counters the relatively low frequency vibrations from the chassis.

Claims

1. An active suspension system for isolating a first body from vibration in a second body, said active suspension system comprising:

at least one hydraulic actuator connected between the first body and the second body and comprising a cylinder and a piston defining a first chamber and a second chamber in the cylinder;

a hydraulic circuit node in continuous fluid communication with the first chamber and to the second chamber;

a hydraulic spring connected to the hydraulic circuit node;

a valve which is electrically operable to selectively connect the hydraulic circuit node to a source of pressurized hydraulic fluid or to a reservoir to control the flow of hydraulic fluid between the hydraulic circuit node and the source or reservoir;

a first sensor which detects motion of the first body and produces an electrical signal indicating that motion; and

a controller connected to the first sensor and the valve, the controller responding to the electrical signal from the first sensor by applying the control signal to the valve to produce movement of the piston relative to the cylinder, thereby attenuating transmission of vibration from the second body to the first body.

2. The apparatus as recited in claim 1 wherein the valve has a third position in which the node is isolated from both the source of pressurized hydraulic fluid and the reservoir.

3. The apparatus as recited in claim 1 wherein the hydraulic circuit node is directly connected to both the first chamber and the second chamber.

4. The apparatus as recited in claim 1 further comprising:

a check valve coupling the first chamber to the second chamber; and

a fixed orifice connected in parallel with the check valve.

5. The apparatus as recited in claim 1 further comprising:

a check valve coupling the first chamber to the second chamber; and

a variable orifice connected in parallel with the check valve and coupled to the controller which varies the variable orifice.

6. The apparatus as recited in claim 1 wherein the first sensor detects an amount of displacement between of the first body and the second body.

7. The apparatus as recited in claim 6 further comprising a second sensor detects acceleration of the first body.

8. The apparatus as recited in claim 6 further comprising a second sensor detects rotation of the first body.

9. The apparatus as recited in claim 1 wherein the first sensor detects acceleration of the first body.

10. An active suspension system for isolating a first body from vibration in a second body, said active suspension system comprising:

at least one hydraulic actuator connected between the first body and the second body and comprising a cylinder and a piston received within the cylinder, the piston dividing the cylinder into a first chamber above the piston and a second chamber below the piston;

a hydraulic circuit node directly connected to the first chamber and in continuous fluid communication with the second chamber;

an accumulator connected to the hydraulic circuit node;

a three-position valve which is electrically operable to connect the hydraulic circuit node to a source of pressurized hydraulic fluid in a first position and to a reservoir in a second position, and to isolate the hydraulic circuit node from both the source and the reservoir in a third position;

a first sensor which detects an amount of displacement between of the first body and the second body;

a second sensor detects acceleration of the first body; and

a controller which responds to the first sensor and to the second sensor by operating the valve to move the piston relative to the cylinder thereby attenuating transmission of vibration from the second body to the first body.

11. The apparatus as recited in claim 10 wherein the hydraulic circuit node is directly connected to the first chamber and to the second chamber.

12. The apparatus as recited in claim 10 further comprising:

a check valve coupling the first chamber to the second chamber, wherein fluid can flow through the first check valve only in a direction from the first chamber to the second chamber; and

a fixed orifice connected in parallel with the check valve.

13. The apparatus as recited in claim 10 further comprising:

a check valve coupling the first chamber to the second chamber, wherein fluid can flow through the first check valve only in a direction from the first chamber to the second chamber; and

a variable orifice connected in parallel with the check valve and coupled to the controller which varies the variable orifice.

14. An active suspension system for isolating a first body from vibration in a second body, said active suspension system comprising:

a first sensor which detects motion of the first body in a first degree of freedom;

a second sensor which detects motion of the first body in a second degree of freedom;

a third sensor which detects motion of the first body in a third degree of freedom;

three vibration isolators connected between the first body and the second body and each vibration isolator comprising;

(a) a hydraulic actuator having a cylinder and a piston which defines a first chamber and a second chamber in the cylinder,

(b) a hydraulic circuit node connected to the first chamber and coupled to the second chamber,

(c) an accumulator connected to the hydraulic circuit node, and

(d) a three-position valve which is electrically operable to selectively connect the hydraulic circuit node to a source of pressurized hydraulic fluid or a reservoir; and

a controller responding to signals from the first, second, and third sensors by selectively operating the valve of each of the three vibration isolators to operate the respective hydraulic actuator to attenuate transmission of vibration from the second body to the first body.

15. The apparatus as recited in claim 14 wherein the hydraulic circuit node of each hydraulic actuator is directly connected to the first chamber and to the second chamber of the respective cylinder.

16. The apparatus as recited in claim 14 wherein each hydraulic actuator further comprises:

a check valve coupling the first chamber to the second chamber of the respective cylinder; and

a fixed orifice connected in parallel with the check valve.

17. The apparatus as recited in claim 14 wherein each hydraulic actuator further comprises:

a check valve coupling the first chamber to the second chamber of the respective cylinder; and

a variable orifice connected in parallel with the check valve and connected to the controller which varies the variable orifice.

18. The apparatus as recited in claim 14 wherein each hydraulic actuator further comprises a displacement sensor which detects an amount of displacement between of the first body and the second body.

19. The apparatus as recited in claim 14 wherein at leas one of the first sensor, the second sensor, and the third sensor is an accelerometer.

20. The apparatus as recited in claim 14 wherein at least one of the first sensor, the second sensor, and the third sensor is a gyroscope.