GB2201788A - Variable inductance position transducer - Google Patents

Variable inductance position transducer Download PDF

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Publication number
GB2201788A
GB2201788A GB08803575A GB8803575A GB2201788A GB 2201788 A GB2201788 A GB 2201788A GB 08803575 A GB08803575 A GB 08803575A GB 8803575 A GB8803575 A GB 8803575A GB 2201788 A GB2201788 A GB 2201788A
Authority
GB
United Kingdom
Prior art keywords
winding
transducer
apertures
variable inductance
tubular member
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Granted
Application number
GB08803575A
Other versions
GB2201788B (en
GB8803575D0 (en
Inventor
Christopher Andrew Willis
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
ZF International UK Ltd
Original Assignee
Lucas Industries Ltd
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by Lucas Industries Ltd filed Critical Lucas Industries Ltd
Publication of GB8803575D0 publication Critical patent/GB8803575D0/en
Publication of GB2201788A publication Critical patent/GB2201788A/en
Application granted granted Critical
Publication of GB2201788B publication Critical patent/GB2201788B/en
Anticipated expiration legal-status Critical
Expired - Lifetime legal-status Critical Current

Links

Classifications

    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
    • G01D3/00—Indicating or recording apparatus with provision for the special purposes referred to in the subgroups
    • G01D3/02—Indicating or recording apparatus with provision for the special purposes referred to in the subgroups with provision for altering or correcting the law of variation
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01D—MEASURING NOT SPECIALLY ADAPTED FOR A SPECIFIC VARIABLE; ARRANGEMENTS FOR MEASURING TWO OR MORE VARIABLES NOT COVERED IN A SINGLE OTHER SUBCLASS; TARIFF METERING APPARATUS; MEASURING OR TESTING NOT OTHERWISE PROVIDED FOR
    • G01D3/00—Indicating or recording apparatus with provision for the special purposes referred to in the subgroups
    • G01D3/028—Indicating or recording apparatus with provision for the special purposes referred to in the subgroups mitigating undesired influences, e.g. temperature, pressure
    • G01D3/036—Indicating or recording apparatus with provision for the special purposes referred to in the subgroups mitigating undesired influences, e.g. temperature, pressure on measuring arrangements themselves

Abstract

A variable inductance transducer includes a winding 11 which is wound about a cylindrical former 10 and a tubular member 12 formed from electrically conductive material which is located about the winding and is movable axially relative thereto. The tubular member 13 is provided with a number of apertures along its length in order to improve the linearity of the transducer. An additional winding in a separate former may be provided to enable temperature compensation, the two windings alternately being connected in parallel with a capacitor to determine the frequency of an oscillator connected to a frequency to voltage convertor. <IMAGE>

Description

"TRANSDUCER" This invention relates to a variable inductance transducer of the kind including a winding wound upon an elongated cylindrical former and a tubular member formed from electrically conductive material located about the winding and movable axially relative thereto.
As the member moves axially relative to the former and winding the inductance of the winding varies. The winding can form part of the frequency determining network of an oscillator the frequency of which will vary as the member is moved. The variation in the frequency of the oscillator can therefore be used to provide a signal representative of the movement of the member.
A major problem with such a transducer is that the change of inductance for a given movement of the member varies substantially over the range of movement of the member and in practice the range of movement has to be restricted. The object of the present invention is to provide a transducer of the kind specified in an improved form According to the invention in a transducer of the kind specified said tubular member is provided with apertures at intervals along its length.
In the preferred arrangement the apertures are in the form of holes drilled or punched into the member at intervals along its length, the intervals being smaller towards the end of the member which remains about the winding as the member is moved. In the example the member is formed from aluminium and is approximately 130mm long the winding being of substantially the same length. The practical range of relative movement of the winding and the member is approximately 104mm.
In the accompanying drawings: Figure 1 shows a cross section of part of the transducer, Figure 2 shows a plan view of part of the transducer of Figure 1, and Figures 3 and 4 are view similar to Figure 2 showing alternative forms for the part.
As shown in Figure 1 the transducer comprises a cylindrical former 10 about which is wound a winding 11. The tubular member is indicated at 12 and is movable axially relative to the former from a position in which it fully surrounds the winding. As shown in Figure 2, the member is provided with a row of apertures in the form of circular holes 13 which are of the same size the intervals between the holes becoming smaller towards the end of the member which remains about the winding as the member is moved.
Figure 3 shows a modification in which the holes are circular but not the same size and Figure 4 shows that at least some of the apertures can be in the form of a slot 14.
Ths size and disposition of the apertures depends upon the dimensions of the winding and also the range of relative movement of the winding and tubular member.
In order to provide for temperature compensation, it is proposed to provide an additional winding on a separate former which is exposed to the same temperature as the frequency determining winding and to use the two windings in conjunction with a capacitor, as the frequency determining component of an oscillator. The windings are switched in turn in parallel with the capacitor and the resultant output of the oscillator is supplied to a processing circuit which includes a frequency to voltage converter so that the output voltage is representative of the relative position of the tubular member and the winding.
Conveniently the switching of the windings across the capacitor is effected by means of semi-conductor switches.

Claims (5)

1. A variable inductance transducer comprising a winding wound upon an elongated cylindrical former and a tubular member formed from electrically conductive material located about the winding and movable axially relative thereto, said tubular member being provided with apertures at intervals along its length.
2. A transducer according to Claim 1 in which the intervals between the apertures become smaller towards the end of the member which remains about the winding as the member is moved.
3. A transducer according to Claim 1 or Claim 2 in which said apertures are in the form of circular holes.
4. A transducer according to Claim 1 in which at least some of said apertures are in the form of slots.
5. A variable inductance transducer comprising the combination and arrangement of parts substantially as hereinbefore described with reference to the accompanying drawings.
GB8803575A 1987-03-03 1988-02-16 Transducer Expired - Lifetime GB2201788B (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB878704900A GB8704900D0 (en) 1987-03-03 1987-03-03 Transducer

Publications (3)

Publication Number Publication Date
GB8803575D0 GB8803575D0 (en) 1988-03-16
GB2201788A true GB2201788A (en) 1988-09-07
GB2201788B GB2201788B (en) 1990-10-10

Family

ID=10613218

Family Applications (2)

Application Number Title Priority Date Filing Date
GB878704900A Pending GB8704900D0 (en) 1987-03-03 1987-03-03 Transducer
GB8803575A Expired - Lifetime GB2201788B (en) 1987-03-03 1988-02-16 Transducer

Family Applications Before (1)

Application Number Title Priority Date Filing Date
GB878704900A Pending GB8704900D0 (en) 1987-03-03 1987-03-03 Transducer

Country Status (8)

Country Link
US (1) US4810990A (en)
JP (1) JPS63233301A (en)
DE (1) DE3805667A1 (en)
ES (1) ES2006837A6 (en)
FR (1) FR2611895B1 (en)
GB (2) GB8704900D0 (en)
IT (1) IT8819593A0 (en)
SE (1) SE463837B (en)

Cited By (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2207765A (en) * 1987-08-05 1989-02-08 Man Design Co Length measuring device
EP0422458A2 (en) * 1989-10-06 1991-04-17 Robert Bosch Gmbh Displacement transducer
GB2435518A (en) * 2006-02-28 2007-08-29 Alexy Davison Karenowska Position sensor with electromagnetic field generator and shield

Family Cites Families (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US2954538A (en) * 1956-05-15 1960-09-27 Avco Mfg Corp Temperature compensated permeabilitytuned inductor
US3400352A (en) * 1962-01-02 1968-09-03 Varian Associates Encapsulated inductor with external adjustable means for selectively varying the inductance
US3471844A (en) * 1966-07-08 1969-10-07 Joseph F Schugt Position responsive signal generator
IT1108522B (en) * 1978-12-19 1985-12-09 Sandretto Spa APPARATUS TO DETECT THE POSITION OF A MOVING BODY COMPARED TO A FIXED SUPPORT BODY
EP0232253A4 (en) * 1985-07-29 1990-09-26 Nicholas F. D'antonio Inductance systems

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB2207765A (en) * 1987-08-05 1989-02-08 Man Design Co Length measuring device
GB2207765B (en) * 1987-08-05 1991-09-18 Man Design Co Length measuring device
EP0422458A2 (en) * 1989-10-06 1991-04-17 Robert Bosch Gmbh Displacement transducer
EP0422458A3 (en) * 1989-10-06 1991-05-29 Robert Bosch Gmbh Displacement transducer
GB2435518A (en) * 2006-02-28 2007-08-29 Alexy Davison Karenowska Position sensor with electromagnetic field generator and shield
GB2435518B (en) * 2006-02-28 2009-11-18 Alexy Davison Karenowska Position sensor
US8018222B2 (en) 2006-02-28 2011-09-13 Alexy Davison Karenowska Electromagnetic field-based position sensor

Also Published As

Publication number Publication date
ES2006837A6 (en) 1989-05-16
DE3805667A1 (en) 1988-09-15
SE8800694D0 (en) 1988-02-29
GB2201788B (en) 1990-10-10
GB8803575D0 (en) 1988-03-16
JPS63233301A (en) 1988-09-29
FR2611895B1 (en) 1991-08-23
FR2611895A1 (en) 1988-09-09
SE8800694L (en) 1988-09-04
SE463837B (en) 1991-01-28
US4810990A (en) 1989-03-07
GB8704900D0 (en) 1987-04-08
IT8819593A0 (en) 1988-02-29

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Legal Events

Date Code Title Description
PCNP Patent ceased through non-payment of renewal fee

Effective date: 20000216