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Drain System for a Linear Actuator

IP.com Disclosure Number: IPCOM000043136D
Original Publication Date: 1984-Jul-01
Included in the Prior Art Database: 2005-Feb-04
Document File: 2 page(s) / 36K

Publishing Venue

IBM

Related People

Alvarez, JM: AUTHOR [+3]

Abstract

This apparatus provides reduction of external oil leakage from an open-frame linear actuator. Many hydraulic actuators have a case enclosing the final drive components. This case allows hydraulic fluid leaking past the high pressure seals to drain back to the hydraulic reservoir. The linear actuator 10, shown in Fig. 1 operating a robot arm, has an open frame that exposes the final drive components. The linear actuator 10 design is such that it is very difficult to seal the case to allow hydraulic fluid to drain back to the reservoir. The high speeds required in robotic applications dictate extensive up and down motions of the pistons 12 which make bellows or other ways of enclosing the case not practical because of wear. Sealing the case would require extensive sliding seal surfaces joined at right angles.

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Drain System for a Linear Actuator

This apparatus provides reduction of external oil leakage from an open-frame linear actuator. Many hydraulic actuators have a case enclosing the final drive components. This case allows hydraulic fluid leaking past the high pressure seals to drain back to the hydraulic reservoir. The linear actuator 10, shown in Fig. 1 operating a robot arm, has an open frame that exposes the final drive components. The linear actuator 10 design is such that it is very difficult to seal the case to allow hydraulic fluid to drain back to the reservoir. The high speeds required in robotic applications dictate extensive up and down motions of the pistons 12 which make bellows or other ways of enclosing the case not practical because of wear. Sealing the case would require extensive sliding seal surfaces joined at right angles. Such a sealing method is expensive, tends to increase friction, and prone to leakage. Fig. 1 shows the linear actuator 10 with the open frame construction. The linear actuator consists of 4 pistons 12 having a cam follower 14 at the end of each piston rod. The cam followers 14 cooperate with a cam 16 mounted on the arm 18 to provide motion thereof. Fig. 2 shows the linear actuator design prior to this improvement. Oil in the high pressure chamber 20 would leak past the elastomer seal 22 onto external machine components. Fig. 3 shows the improvement. A close tolerance labyrinth seal 24 isolates the high pressure chamber 20 fro...