Measuring apparatus

• US 6,729,036 B2
• Filed: 06/12/2002
• Issued: 05/04/2004
• Est. Priority Date: 06/13/2001
• Status: Active Grant

• Current Assignee: Smw-Autoblok Spannsysteme GmbH
• Original Assignee: Smw-Autoblok Spannsysteme GmbH
• Inventors: Bercher, Heiuvich, Denzel, Johannes Markus
• Primary Examiner(s): Bennett, G. Bradley
• Assistant Examiner(s): Gonzalez, Madeline
• Application Number:
  US10/171,061
• Publication Number:
  US 20020189123A1
• Time in Patent Office: 692 Days
• Field of Search: 337/06, 337/07, 337/08, 33D/IG.1, 33D/IG.15
• US Class Current: 33/706
• CPC Class Codes: F15B 15/2846 using detection of markings, e.g. markings on the piston rod
• CPC Class Codes: G01B 7/003 for measuring position, not involving coordinate determination coordinate measuring G01B7/004
• CPC Class Codes: G01D 5/2013 by a movable ferromagnetic element, e.g. a core G01D5/2033 takes precedence
• CPC Class Codes: G01D 5/202 by movable a non-ferromagnetic conductive element G01D5/2033 takes precedence
• CPC Class Codes: Y10S 33/15 Piston position indicator

Abstract

In a measuring apparatus (1) for contactlessly determining the position of two components (11 and 12 respectively) which are displaceable relative to each other and which are in the form of a measurement value sender (11) and a sensor (21) co-operating therewith, the measurement value sender (11) is in the form of a switching ring comprising a metallic material and connected to the displaceable component, and the sensor (21) comprises a plurality of inductive measuring heads which are arranged over the displacement range of the switching ring and which produce an electromagnetic measuring field composed of individual fields. The measuring heads are also connected to a computing unit (25) in which there is stored in a memory the signal configuration ascertained upon calibration of the measuring apparatus (1); the position of the displaceable component can be determined after a displacement movement of the switching ring (12), by comparison of the signals produced, with the stored signal configuration.

This design configuration provides that incorrect measurements are reliably avoided and that a magnetic and a mechanical shock do not have to be tolerated as the measuring apparatus (1) is operational without magnets.

Claims

1. A measuring apparatus (1) for contactlessly determining the position of a displacement piston (6) fitted in a cylinder (5) and drivingly connected to clamping jaws (3) of a power-operated chuck (2), the apparatus comprising a measurement value sender (11) moveable with said piston and a sensor (21) co-operating therewith, the sensor (21) comprising a plurality of inductive measuring heads (22, 22′

, 22″

, 22′

″

. . . ) arranged over a displacement range of the measurement value sender (11), the measuring heads (22, 22′

, 22″

, 22′

″

. . . ) being connected to a computing unit (25) which has an evaluation circuit and in which there is stored in a memory a signal configuration (26) of the individual measuring heads (22, 22′

, 22″

, 22′

″

. . . ), wherein position of the piston is determined after an axial displacement movement of the piston and said measurement value sender (11) by comparison of signals respectively produced thereby in a measuring field (24) with the stored signal configuration (26), wherein said measurement value sender (11) comprises a switching ring (12) of a metallic material, and is provided on a peripheral surface which is proximate said sensor (21), with a profiling (13) formed by at least one recess (14) provided therein.

2. A measuring apparatus as set forth in claim 1 wherein flanks (15, 15′

, 15″

, 15′

″

) of recesses (14, 14″

) are transverse to an axis of the switching ring (12) and are of a curved configuration.

3. A measuring apparatus as set forth in claim 2 wherein the recesses (14) and projections (16) formed thereby are of equal width.

4. A measuring apparatus as set forth in claim 3 wherein lateral spacing (a) of the measuring heads (22, 22′

, 22″

, 22′

″

. . . ) is different from lateral spacing (b) of two of the flanks (15), which are directed in the same direction as two of the projections (16).

5. A measuring apparatus as set forth in claim 4 wherein the spacing (a) of the measuring heads (22, 22′

, 22″

, 22′

″

. . . ) is in a ratio to the spacing (b) of the flanks (15) of three to four.

6. A measuring apparatus as set forth in claim 1 wherein two recesses (14, 14′

) are arranged at a lateral spacing relative to each other in the peripheral surface of the switching ring (12).

7. A measuring apparatus as set forth in claim 1 wherein the measuring heads (22, 22′

, 22″

, 22′

″

. . . ) are arranged equidistantly in a line over the displacement range of the switching ring (12).

8. A measuring apparatus as set forth in claim 1 wherein the measuring heads (22, 22′

, 22″

, 22′

″

. . . ) are respectively formed from a ferrite shell core and a coil pack.

9. A measuring apparatus as set forth in claim 1 wherein the measuring heads (22, 22′

, 22″

, 22′

″

. . . ) produce an electromagnetic field (24) comprising a plurality of individual fields of (23, 23′

, 23″

, 23′

″

. . . ).

10. The measuring apparatus in accordance with claim 1 wherein said switching ring is provided with the profiling on a whole of the peripheral surface, such that interaction of said switching ring and said sensor continue upon rotational movement of said switching ring.

11. A measuring apparatus for contactlessly determining a position of a displacement piston, the apparatus comprising:

a measurement value sender moveable with the piston, and

a sensor for co-operation with said measurement value sender, said sensor comprising a plurality of inductive measuring heads arranged over a displacement range of the measurement value sender, the measuring heads being connected to a computer unit having an evaluation circuit and in which there is stored in a memory a signal configuration of the individual measuring heads;

wherein a position of the piston is determined after an axial displacement movement of the piston and said measurement value sender by comparison of signals respectively produced thereby in a measuring field with the stored signal configuration;

wherein said measurement value sender comprises a ring of a metallic material and is provided on a peripheral surface thereof, which is proximate said sensor, with a profiling formed by at least one recess provided therein; and

wherein the measuring heads produce an electromagnetic field comprising a plurality of individual fields.