Fluid-powered actuator having an internal position sensor and a sensor module therefor

• US 8,448,563 B2
• Filed: 08/29/2008
• Issued: 05/28/2013
• Est. Priority Date: 08/29/2008
• Status: Active Grant

• Current Assignee: Cowan Dynamics Inc.
• Original Assignee: Cowan Dynamics Inc.
• Inventors: Wenker, Ren, Gagn, Daniel
• Primary Examiner(s): Lopez, F. Daniel
• Application Number:
  US12/201,137
• Publication Number:
  US 20100050863A1
• Time in Patent Office: 1,733 Days
• Field of Search: 62/5.R
• US Class Current: 92/5.R
• CPC Class Codes: F15B 15/283 using a cable wrapped on a drum and attached to the piston
• CPC Class Codes: F15B 15/2861 using magnetic means
• CPC Class Codes: F15B 15/2876 using optical means, e.g. laser
• CPC Class Codes: F15B 15/2884 using sound, e.g. ultrasound
• CPC Class Codes: F15B 15/2892 characterised by the attachment means

Abstract

A fluid-powered actuator comprises a cylindrical body having a base proximate one extremity and a head proximate another extremity, a piston-rod assembly and a sensor module made of a removable cover and a position sensor. The piston-rod assembly is slidably mounted inside the cylindrical body. The base is provided with an opening adapted to accommodate the sensor therethrough. In operation, the cover seals the opening. The position sensor is mounted to an internal face of the cover so that the position sensor is operatively located inside the cylindrical body when the cover is in place. The position sensor is operative to measure a position of the piston-rod assembly. A sensor module adapted to sealably close the opening in the base comprises the position sensor mounted to an internal face of a cover structure. In operation, the position sensor is operatively located inside the actuator when the cover structure closes the opening.

Claims

1. A fluid-powered actuator comprising:

a cylindrical body having a base proximate one extremity and a head proximate another extremity, said base having an opening;

a piston-rod assembly slidably mounted inside said cylindrical body, the piston-rod assembly defining within the cylindrical body a first chamber contiguous to the base and a second chamber contiguous to the head, each chamber communicating independently with an external source of pressurized fluid used to control the position of the piston-rod assembly;

and a readily replaceable sensor module comprising a removable cover operative to sealably close said opening and a position sensor mounted to an internal face of said cover so that said position sensor is operatively located inside the first chamber of said cylindrical body when said cover is in place, said position sensor being operative to measure a position of said piston-rod assembly and being dimensioned to pass easily through said opening, such that said sensor module is selectively replaceable when said actuator is in service without having to disconnect the actuator from where it is mounted and while maintaining the application of pressurized fluid to the second chamber and thereby positioning and holding the piston-rod assembly in its fully retracted position,

wherein said position sensor is a draw wire transducer using a wire, said wire being attached to said piston-rod assembly with a releasable connection.

2. The actuator of claim 1 wherein the wire is attached to the piston-rod assembly through a threaded connection.

3. The actuator of claim 1 further comprising an analog converter connected to said position sensor for converting a signal from said position sensor to an analog electric signal.

4. The actuator of claim 3 wherein said converter is mounted on said internal face of said cover.

5. The actuator of claim 4 further comprising an analog connector, said analog connector being located on an external face of said cover, said analog connector being connected to said position sensor.

6. The actuator of claim 5 further comprising digital discrete switches and a digital connector, said digital discrete switches being operatively located inside said cylindrical body to measure at least two positions of said piston-rod assembly, said digital connector being located on the external face of said cover, said digital connector being connected to the digital discrete switches of said position sensor.

7. A fluid-powered actuator comprising:

a cylindrical body defined by a side wall and two end walls that seal the extremities of the side wall, one of the end wall having a sealably-closable opening therein;

a piston and rod assembly slidably mounted inside the cylindrical body with the rod protruding through one of the end walls;

said piston defining with the end walls two chambers within the cylindrical body, each chamber communicating independently with an external control device for positioning the piston and rod assembly within the cylindrical body by applying pressurized fluid to each chamber;

and a readily replaceable sensor module comprising a removable cover operative to sealably close said opening in one of the end walls and a position sensor mounted to an internal face of said cover so that said position sensor is operatively located inside the cylindrical body when the cover is in place, the position sensor being operative to measure a position of the piston and rod assembly and being dimensioned to pass easily through the opening, such that the sensor module is selectively replaceable when the actuator is in service without having to disconnect the actuator from where it is mounted, and while maintaining the application of pressurized fluid to the chamber remote from the end wall having the opening therein,

wherein each chamber communicates with the external source of pressurized fluid via a port extending through one of the end walls,

wherein the rod of the piston and rod assembly protrudes through a first end wall and said opening is located in the second end wall,

wherein said cover as adapted to fit at least partially within said opening, and

wherein said position sensor is a draw wire transducer using a wire, said wire being attached to said piston-rod assembly with a releasable connection.

8. The actuator of claim 7 wherein the wire is attached to the piston-rod assembly through a threaded connection.

9. The actuator of claim 7 further comprising an analog converter connected to said position sensor for converting a signal from said position sensor to an analog electric signal.

10. The actuator of claim 9 wherein said converter is mounted on said internal face of said cover.

11. The actuator of claim 10 further comprising an analog connector, said analog connector being located on an external face of said cover, said analog connector being connected to said position sensor.

12. The actuator of claim 11 further comprising digital discrete switches and a digital connector, said digital discrete switches being operatively located inside said cylindrical body to measure at least two positions of said piston and rod assembly, said digital connector being located on the external face of said cover, said digital connector being connected to the digital discrete switches of said position sensor.