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Hydraulic Rotary Motor

IP.com Disclosure Number: IPCOM000045169D
Original Publication Date: 1983-Feb-01
Included in the Prior Art Database: 2005-Feb-06
Document File: 2 page(s) / 48K

Publishing Venue

IBM

Related People

Cummins, AW: AUTHOR [+3]

Abstract

A hydraulic rotary actuator was initially designed for use in a robot since none of the commercially available actuators could provide the servo response required. The design differed from those commercially available in that the internal seals were eliminated. Since the seals were eliminated, it became necessary to manufacture the stator, rotor and inside diameter of the unit to extremely close tolerances. It was assumed that the friction of the seals against the inner bore as affecting the servo response time. Ball bearings were used to support the rotor shaft against the side loads. Since the actuator functions in an oscillating motion, instead of a continuous rotating motion, flat spots were being worn on the balls of the ball bearing, compounding the tolerance problem.

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Hydraulic Rotary Motor

A hydraulic rotary actuator was initially designed for use in a robot since none of the commercially available actuators could provide the servo response required. The design differed from those commercially available in that the internal seals were eliminated. Since the seals were eliminated, it became necessary to manufacture the stator, rotor and inside diameter of the unit to extremely close tolerances. It was assumed that the friction of the seals against the inner bore as affecting the servo response time. Ball bearings were used to support the rotor shaft against the side loads. Since the actuator functions in an oscillating motion, instead of a continuous rotating motion, flat spots were being worn on the balls of the ball bearing, compounding the tolerance problem. All of this resulted in an actuator that was erratic in servo response and torque. Excessive external oil leakage was also prevalent.

A commercially available hydraulic rotary actuator was selected. The actuator, as commercially available, contained seal slots 10 that measured .120 inches wide on the rotor 12 and .115" wide on the stator 14. The seals originally were quad type (square) and .097 inches wide. As a result, a side flexing of the seal occurred whenever pressure was applied, which adversely affected the torque and servo response.

The quad seals were replaced with round seals 16 and 18 to provide a single point of contact. A .020 inches shim 20, cut in the same...