Wear monitor

• US 6,318,147 B1
• Filed: 07/22/1999
• Issued: 11/20/2001
• Est. Priority Date: 07/31/1998
• Status: Expired due to Fees

• Current Assignee: Hoerbiger Ventilwerke GmbH
• Original Assignee: Hoerbiger Ventilwerke GmbH
• Inventors: Zeppelzauer, Wolfgang, Steinrück, Peter, Pohl, Alfred, Seifert, Franz
• Primary Examiner(s): NOLAND, THOMAS
• Application Number:
  US09/358,556
• Time in Patent Office: 852 Days
• Field of Search: 73/7, 731/20, 735/93, 92/5.R
• US Class Current: 73/7
• CPC Class Codes: G01D 5/485 using magnetostrictive devices

Abstract

A wear monitor suitable in particular for monitoring the wear and tear of rider rings (7) on the pistons (5) of horizontally operating reciprocating compressors presents a sensor (9) that monitors the thickness of the rider ring (7) at least indirectly, is arranged in the area of the rider ring (7) in such a way as to move together with it and can be interrogated without contact via a motionless interrogation unit (16), which communicates with an evaluation unit (18). The sensor (9) preferably presents a passive surface acoustic wave element (23), whose electromagnetic reflection behavior depends on the thickness of the rider ring (7) consequent upon the degree of wear and tear thereof and which communicates with a sensor antenna (19) moving together with it, while the interrogation unit (16) presents a communicating interrogation antenna (20).

Claims

1. A wear monitor for monitoring the wear and tear in a moving component (7) relative to a motionless surface (6) and pressed and rubbing against the same, for monitoring the wear and tear of piston rings and rider rings with a sensor (9) monitoring the thickness of the moving component (7) at least indirectly, which sensor (9) communicates with an evaluation unit (18), wherein said sensor (9) is arranged in the area of said moving component (7) in such a way as to move with it and can be interrogated without contact via a motionless interrogation unit (16), which communicates with said evaluation unit (18);

and

wherein said sensor (9) presents a passive surface acoustic wave element (23) having an acoustic reflection behavior that depends on the thickness of said moving component (7) consequent upon the wear and tear suffered by the same and which communicates with a sensor antenna (19) moving together with it, and that said interrogation unit (16) presents an interrogation antenna (20) connected to it.

2. The wear monitor according to claim 1 for monitoring the wear and tear of plastic rider rings (7) on a piston (5) of a piston compressor, wherein the interrogation antenna (20) is situated on the inner cylinder liner or cylinder wall of the cylinder chamber (6) of said piston compressor and connected to interrogation and evaluation units (16, 18) by pressure-tight connections (21) and that the sensor antenna (19) of the surface acoustic wave element (23) is arranged on the piston (5) in such a way that it comes into direct proximity of the interrogation antenna (20) periodically by virtue of the piston movement.

3. The wear monitor according to claim 2, wherein the sensor (9) presents a wear element (24) arranged on the piston (5) in the vicinity of the rider ring (7) and independent thereof, having a degree of erodability which is equal to or slightly more than that of the rider ring (7) and having a radial thickness that can be interrogated through the surface acoustic wave element (23) and the interrogation and evaluation units (16, 18).

4. The wear monitor according to claim 3, wherein the wear element (24) forms an insulator (25) for a plate capacitor (26) linked with a reflection interdigital transformer (IDT 3) of the surface acoustic wave element (23), having a plate on the side of the piston (27) which is formed by the piston (5) or a conducting electrode of the wear element (24) and having an opposing plate formed by the conducting inner cylinder liner or cylinder wall of the cylinder chamber (6) and whose capacity determined by the distance between the two plates supplies to sensor signal via the surface acoustic wave element (23).

5. The wear monitor according to claim 3, wherein the capacity of a plate capacitor (26) together with the inductance of connecting cables forms an impedance Z in the vicinity of respective serial resonance for a reflection interdigital transformer (IDT 3).

6. The wear monitor according to claim 3, wherein the wear element (24) presents a resistance (28) that changes with the reducing thickness and a correspondingly changing inductance (33), which are related to a reflection interdigital transformer (IDT 3) of the surface acoustic wave element (23).

7. The wear monitor according to claim 2, wherein the sensor (9) presents a slide block (34) applied to the piston (5) in the vicinity of the rider ring (7) and independent thereof, with a degree of wear and tear that is negligible with respect to said rider ring (7), which is pressed elastically against the internal wall of the cylinder (6) and acts mechanically upon the surface acoustic wave element (23).

8. The wear monitor according to claim 1, wherein the surface acoustic wave element (23), in addition to a reflection interdigital transformer (IDT 3) influenced by the dependence on the thickness, also present at least one further reflection interdigital transformer (IDT 2) whose acoustic reflection behavior is independent of the thickness of the moving component.