Linear distance measuring device using a moveable magnet interacting with a sonic waveguide

• US 3,898,555 A
• Filed: 12/19/1973
• Issued: 08/05/1975
• Est. Priority Date: 12/19/1973
• Status: Expired due to Term

• Current Assignee: MTS Systems Corporation (Illinois Tool Works Inc.)
• Original Assignee: Jacob Tellerman
• Inventors: Tellerman, Jacob
• Primary Examiner(s): Corcoran, Robert J.
• Application Number:
  US05/426,075
• Time in Patent Office: 594 Days
• Field of Search: 324/34R,34D,34PS,34MA,34L,34ST,18C,189 333/3M
• US Class Current: 324/207.13
• CPC Class Codes: G01B 17/00 Measuring arrangements characterised by the use of infrasonic, sonic or ultrasonic vibrations
• CPC Class Codes: G01D 5/247 using time shifts of pulses
• CPC Class Codes: G01D 5/485 using magnetostrictive devices

Abstract

A linear distance measuring device is disclosed in which the time it takes a torsion pulse to traverse a sonic waveguide from a movable magnet to a pulse responsive element is determined and converted to a measurement of the distance from the movable magnet to the pulse responsive element. The position of the magnet, which is moved by an external means such as a machine tool element, can thus be determined precisely.

Claims

1. A linear distance measuring device comprising, sonic waveguide means formed of a tubular member of magnetostrictive material, electrical conducting means located within said waveguide means, said conducting means having an outside diameter less than the inside diameter of said waveguide means and being in unattached relationship with said waveguide means, pulse generating means for applying electrical pulses to said electrical conducting means, magnet means movable along said waveguide means, mode converter means located in a fixed position along said waveguide means for generating an electrical signal in response to the reception of a sonic torsion pulse launched by said magnet means when an electrical pulse is applied to said electrical conducting means, circuit responsive means for measuring the time interval between the application of an electrical pulse to said electrical conducting means and the reception of a sonic pulse by said signal generating means, and means responsive to said circuit means for indicating the position of said movable magnet means relative to said electrical signal generating means.

2. A linear distance measuring device comprising an electrical conducting element, an associated sonic pulse conducting member of a magnetostrictive material, said electrical conducting element and said sonic pulse conducting member being substantially parallel to one another and physically separated so that a sonic pulse transmitted by said sonic pulse conducting member is not attenuated by said electrical conducting element, magnet means movable along said sonic pulse conducting member, pulse generating means for applying electrical pulses to said electrical conducting element to produce a pulsing magnetic field in said sonic pulse conducting member, means located along said sonic pulse conducting member for generating an electrical signal in response to the reception of a sonic pulse launched by said magnet means when an electrical pulse is applied to said electrical conducting element, circuit means responsive to a pulse from said pulse generating means and to a signal from said signal generating means, and means responsive to said circuit means for indicating the position of said movable magnet means relative to said electrical signal generating means.

3. A linear distance measuring device comprising, an electrical conductor, sonic waveguide means comprising a tubular magnetostrictive member concentric with said electrical conductor, said tubular member having an inside diameter greater than the outside diameter of said electrical conductor, said electrical conductor being in unattached relationship with said tubular member, permanent magnet means movable along said waveguide means, pulse generating means for applying electrical pulses to said electrical conductor to produce a circular magnetic field in said waveguide means, mode converter means connected to said waveguide means for generating an electrical signal in response to the reception of a sonic torsion pulse launched by said permanent magnet means when an electrical pulse is applied to said electrical conductor, circuit means responsive to a pulse from said pulse generating means and to a signal from said signal generating means, and means responsive to said circuit means for indicating the position of said movable magnet means relative to said electrical signal generating means.

4. A linear distance measuring device comprising, sonic waveguide means formed of a tubular member, an electrical conducting element provided within said tubular member in parallel spaced relationship thereto and in unattached relationship with said tubular member, magnet means movable along said waveguide mEans, pulse generating means for applying electrical pulses to said electrical conducting element, means located along said waveguide means for generating an electrical signal in response to the reception of a sonic pulse launched by said magnet means when an electrical pulse is applied to said electrical conducting element, circuit means for providing an analogue signal that corresponds to the time interval between the application of an electrical pulse to said electrical conducting element and the reception of a sonic pulse by said signal generating means, and means responsive to said circuit means for indicating the position of said movable magnet means relative to said electrical signal generating means.

5. A linear distance measuring device comprising, a tubular sonic waveguide means, a wire element threaded axially through said waveguide means, said wire element being unattached to said waveguide means so that a sonic pulse transmitted by said waveguide means is unattenuated by said wire element, permanent magnet means movable along said waveguide means, pulse generating means for applying electrical pulses to said wire element to produce a pulsing magnetic field in said waveguide means, mode converter means connected to said waveguide means for generating an electrical signal in response to the reception of a sonic torsion pulse launched by said permanent magnet means when an electrical pulse is applied to said wire element, circuit means responsive to a pulse from said pulse generating means and a signal from said converter means for providing an analogue signal that corresponds to the time interval between the application of an electrical pulse to said wire element and the reception of a sonic pulse by said mode converter means, and means responsive to said circuit means for indicating the position of said movable magnet means relative to said mode converter means.

6. A linear distance measuring device comprising, sonic waveguide means formed of a magnetostrictive tubular member, a wire element threaded axially through said waveguide means, said wire element having an outside diameter less than the inside diameter of said waveguide means and being in unattached relationship with said waveguide means, pulse generating means for applying electrical pulses to said wire element to produce a pulsing circumferential magnetic field in said waveguide means, magnet means movable along said waveguide means for producing a longitudinal magnetic field in said waveguide means adjacent said magnet means, means located in a fixed position along said waveguide means for generating an electrical signal in response to the reception of a sonic pulse launched by the interaction of a circumferential magnetic field pulse and the longitudinal magnetic field produced by said magnet means, circuit means responsive to a pulse from said pulse generating means and to a signal from said signal generating means, and means responsive to said circuit means for indicating the position of said movable magnet means relative to said electrical signal generating means.

7. A measuring device according to claim 6 wherein said circuit responsive means includes a D.C. voltage reference source, voltage averaging means, means for connecting said reference source to said voltage averaging means when said pulse generating means applies a pulse to said wire element and for disconnecting said reference source when said signal generating means generates a signal in response to the reception of a sonic pulse, and means for biasing said voltage averaging means in accordance with the desired reference position of the movable magnet means.

8. A measuring device according to claim 7 wherein said circuit responsive means indicates a distance as a function of the voltage produced by said voltage averaging means.

9. A measuring device according to claim 6 wherein the sonic pulses are torsion pulses and wherein said electrical signal generating means is a mode converter comprising a pair of magnetoStrictive tapes secured to opposite sides of said waveguide means, and a pair of coils associated with said tapes for generating an electrical signal when said tapes are pulsed by a sonic torsion pulse travelling along said waveguide means.

10. A measuring device according to claim 6 including shielding means for said sonic pulse responsive signal generating means.

11. A measuring device according to claim 6 wherein said circuit responsive means comprises means for producing an analogue signal indicative of the distance between said movable magnet means and said signal generating means.