Hydraulic rotary actuator with built-in mechanical position feedback

Patent metadata

Field	Value
Publication number	US-10316867-B2
Application number	US-201715454224-A
Country	US
Kind code	B2
Filing date	Mar 9, 2017
Priority date	Mar 9, 2017
Publication date	Jun 11, 2019
Grant date	Jun 11, 2019

Abstract

A rotary actuator includes a central housing; an output shaft that extends through the central housing; a vane that is mechanically coupled to the output shaft and divides the central housing into a first chamber and a second chamber; and a flow control mechanism that is moveable within the central housing and including a high pressure port and a low pressure port for communicating hydraulic fluid into and from the first and second chambers. The flow control mechanism is moveable to position the high pressure port and low pressure port relative to the first chamber and the second chamber for communication of the hydraulic fluid, thereby generating a pressure differential across the chambers. The vane rotates within the central housing in response to the pressure differential, and rotation of the vane drives the output shaft. A motor is configured to receive control signals to drive the movement of the flow control mechanism.

First claim

What is claimed is:

1. A rotary actuator comprising:
a central housing;
an output shaft that extends through the central housing;
a vane that is mechanically coupled to the output shaft and divides the central housing into a first chamber and a second chamber; and
a flow control mechanism that is moveable within the central housing and configured to port high pressure to one side of the vane and low pressure to an opposite side of the vane, thereby generating a pressure differential across the chambers;
wherein the vane rotates within the central housing in response to the pressure differential, and rotation of the vane drives the output shaft;
wherein the flow control mechanism comprises a valve plate that is moveable within the central housing and including a high pressure port and a low pressure port for communicating the working fluid into and from the first and second chambers; and
wherein the valve plate is moveable to position the high pressure port and low pressure port relative to the first chamber and the second chamber for communication of the working fluid, thereby generating the pressure differential across the chambers.

2. The rotary actuator of claim 1 , wherein:
the flow control mechanism is moveable in a first direction between a first position and a second position different from the first position;
in the first position the vane blocks off the high pressure port and the low pressure port to block the flow of the working fluid between the flow control mechanism and the first and second chambers;
when the flow control mechanism is moved to the second position, the high pressure port is positioned to be in fluid communication with the first chamber to permit the flow of the working fluid into the first chamber, and the low pressure port is positioned to be in fluid communication with the second chamber to permit the flow of the working fluid from the second chamber, thereby creating a pressure differential from the first chamber toward the second chamber; and
in response to the pressure differential, the vane rotates in the first direction, thereby driving the output shaft in the first direction, until the vane blocks off the high pressure port and the low pressure port to block the flow of the working fluid between the flow control mechanism and the first and second chambers.

3. The rotary actuator of claim 2 , wherein:
the flow control mechanism is moveable in a second direction opposite to the first direction between a first position and a third position different from the second position;
in the first position the vane blocks off the high pressure port and the low pressure port to block the flow of the working fluid between the flow control mechanism and the first and second chambers;
when the flow control mechanism is moved to the third position, the high pressure port is positioned to be in fluid communication with the second chamber to permit the flow of the working fluid into the second chamber, and the low pressure port is positioned to be in fluid communication with the first chamber to permit the flow of the working fluid from the first chamber, thereby creating a pressure differential from the second chamber toward the first chamber; and
in response to the pressure differential, the vane rotates in the second direction, thereby driving the output shaft in the second direction, until the vane blocks off the high pressure port and the low pressure port to block the flow of the working fluid between the flow control mechanism and the first and second chambers.

4. The rotary actuator of claim 2 , further comprising:
a first cover plate fixed to the central housing; and
a second cover plate fixed to the central housing on an opposite side relative to the first cover plate.

5. The rotary actuator of claim 4 , wherein the first cover plate is an output shaft side cover plate, the first cover plate comprising:
a cover plate high pressure port, and a first fluid path that communicates working fluid from the cover plate high pressure port to the valve plate high pressure port; and
a cover plate low pressure port, and a second fluid path that communicates working fluid from the valve plate low pressure port to the cover plate low pressure port.

6. The rotary actuator of claim 5 , wherein the first cover plate includes:
an inlet that opens into a first kidney port; and
an outlet inlet that opens into a second kidney port;
wherein:
the inlet receives working fluid from the cover plate high pressure port, and the inlet and the first kidney port further form a fluid pathway to communicate working fluid to the valve plate high pressure port;
the outlet transmits hydraulic fluid to the cover plate low pressure port, and the outlet and the second kidney port further form a fluid pathway to communicate working fluid from the valve plate low pressure port; and
the kidney ports have an elongated configuration to maintain a fluid pathway respectively between the valve plate ports and the inlet and outlet of the first cover plate over an entire movement range of the valve plate.

7. The rotary actuator of claim 4 , wherein the second cover plate is a motor side cover plate, the rotary actuator further comprising a motor that is mounted to the second cover plate and controlled to drive the movement of the valve plate.

8. The rotary actuator of claim 1 , wherein the vane extends through the output shaft and perpendicularly to a central axis of rotation that is common to both the output shaft and the flow control mechanism.

9. The rotary actuator of claim 8 , wherein the vane has a first end that slides against a first internal surface of the central housing as the vane rotates, and a second end opposite to the first end that slides against a second internal surface of the central housing as the vane rotates.

10. The rotary actuator of claim 9 , wherein the vane has first and second sealing elements provided respectively at the first and second ends, which isolate the first chamber from the second chamber as the vane rotates so that no working fluid passes directly between the two chambers.

11. The rotary actuator of claim 1 , further comprising a drive mechanism that is controlled to drive the movement of the flow control mechanism.

12. A hydrostatic transmission comprising:
a hydraulic pump;
a hydraulic motor, wherein the hydraulic pump pumps hydraulic fluid to the motor; and
the rotary actuator of claim 1 , wherein the rotary actuator is controlled to control the hydraulic pump to control the flow of hydraulic fluid from the hydraulic pump to the hydraulic motor.

13. The hydrostatic transmission of claim 12 , wherein the output shaft of the rotary actuator is mechanically coupled to the hydraulic pump to control the hydraulic pump, and the output shaft drives rotation of a swash plate associated with the hydraulic pump to control the hydraulic pump.

14. A method of controlling the rotary actuator according to claim 1 to drive the output shaft, the method comprising the steps of:
providing the rotary actuator; and
moving the flow control mechanism to port the high pressure and low pressure relative to the first chamber and the second chamber for communication of the working fluid, thereby generating the pressure differential across the chambers;
wherein the vane rotates within the central housing in response to the pressure differential, and rotation of the vane drives the output shaft.

15. The control method of claim 14 comprising:
moving the flow control mechanism in a first direction between a first position and a second position different from the first position; whe

Assignees

• Parker Hannifin Corp

Inventors

• Carl Blake Adam
• Howland James William

Classifications

• F16H39/04

  with liquid motor and pump combined in one unit · CPC title

• F15B9/09

  with electrical control means · CPC title

• F04B49/002

  Hydraulic systems to change the pump delivery · CPC title

• F15B9/14

  with rotary servomotors · CPC title

• F15B15/12 Primary

  of the oscillating-vane or curved-cylinder type · CPC title