Capacitor type sensor for detecting displacement or load

• US 4,386,386 A
• Filed: 04/17/1981
• Issued: 05/31/1983
• Est. Priority Date: 04/22/1980
• Status: Expired due to Fees

• Current Assignee: Nippon Soken Incorporated 14 Iwaya Shimohasumi-Cho Nishio-Shi Aichi-Ken Japan
• Original Assignee: Nippon Soken, Inc.
• Inventors: Akita, Sigeyuki
• Primary Examiner(s): Goldberg, Elliot A.
• Application Number:
  US06/255,273
• Time in Patent Office: 774 Days
• Field of Search: 361/291, 361/292, 361/290, 361/278, 361/283, 361/400, 73/862.64
• US Class Current: 361/283.1
• CPC Class Codes: G01B 7/001 Constructional details of gauge heads G01B7/012 takes precedence
• CPC Class Codes: G01D 5/2417 by varying separation
• CPC Class Codes: G01L 1/042 of helical springs
• CPC Class Codes: G01L 1/142 using capacitors

Abstract

A capacitor type displacement or load sensor includes a first electrode constituted by an electrically conductive coiled spring capable of expansion and contraction and a second electrode positioned to face the first electrode without making contact therewith. The second electrode is constituted by an electrically conductive coiled spring or a cylindrical electric conductor. The sensor is constructed such that capacitance between the first and second electrodes varies with a change of a gap between the first and second electrodes or an opposing area of the first and second electrodes caused by the relative displacement occurring therebetween.

Claims

1. A capacitor type displacement or load sensor comprising:

a first electrode constituted by an electrically conductive coiled spring capable of expansion and contraction, said first electrode having one end thereof connected to a first conductor disposed on a fixed insulating member of said sensor and the other end thereof connected to a movable insulating member of said sensor; and

a second electrode connected at one end thereof to a second conductor disposed on said fixed insulating member of said sensor and positioned opposite to said first electrode without contacting the same;

whereby capacitance between said first and second electrodes varies in response to the expansion or contraction of said electrically conductive coiled spring, and

wherein said second electrode in constituted also by an electrically conductive coiled spring capable of expansion and contraction,

said second electrode having one end thereof connected to said second conductor on said fixed insulating member of said sensor and the other end thereof connected to said movable insulating member of said sensor, and

both electrically conductive coiled springs of said first electrode and said second electrode are combined to form a double coil spring without making contact with each other, whereby capacitance between said first and second electrodes varies with a change of an axial gap between both electrically conductive coiled springs.

2. A sensor according to claim 1, wherein said sensor further comprises a housing for accommodating said first and second electrodes, and said movable insulating member of said sensor is supported by said housing and coupled to an external object to be measured.

3. A sensor according to claim 1, wherein said sensor further comprises a built-in printed circuit board, and said first and second conductors disposed on said fixed insulating member of said sensor are mounted on said printed circuit board.

4. A capacitor type displacement or load sensor comprising:

a movable electrode constituted by an electrically conductive coiled spring capable of expansion and contraction;

a cup-shaped fixed electrode;

a fixed insulating member mounting first and second conductors to which one end of said movable electrode and that of said fixed electrode are connected respectively;

a movable spring holding insulating member supporting the other end of said conductive coiled spring constituting said movable electrode;

a housing accommodating said movable electrode, said fixed electrode, said fixed insulating member and said movable spring holding insulating member; and

a rod member slidably supported by said housing and having one end thereof coupled to said movable spring holding insulating member and the other end thereof extended outside said housing;

wherein said cup-shaped fixed electrode is positioned inside said movable electrode without contacting the same, and an effective length of said cup-shaped fixed electrode in the direction of expansion or contraction of said movable electrode is made shorter than a minimum length of said movable electrode in the same direction, whereby capacitance between said cup-shaped fixed electrode and said movable electrode varies with a change of an opposing area of said cup-shaped fixed electrode and said movable electrode.

5. A sensor according to claim 4, wherein said cup-shaped fixed electrode has a cup portion having a cylindrical external shape and a boss portion extending outwardly from a central portion of said cup portion, concentrically with said cylindrical external shape and with an outer diameter smaller than that of said cylindrical external shape of said cup portion.

6. A capacitor type displacement or load sensor comprising:

a first movable electrode constituted by an electrically conductive coiled spring capable of expansion and contraction;

a second movable electrode constituted by an electrically conductive coiled spring capable of expansion and contraction and combined with said first movable electrode to form a double coil spring without making contact therewith;

a fixed insulating member mounting first and second conductors to which one end of said first movable electrode and that of said second movable electrode are connected respectively;

a movable spring holding insulating member supporting the other ends of said first and second movable electrodes, respectively;

a housing accommodating said first and second movable electrodes, said fixed insulating member and said movable spring holding insulating member; and

a rod member slidably supported by said housing and having one end thereof coupled to said movable spring holding insulating member and the other end thereof extended outside said housing;

whereby capacitance between said first and second movable electrodes varies in response to the expansion and contraction of said electrically conductive coiled springs.

7. A capacitor type displacement or load sensor comprising:

a first electrode constituted by an electrically conductive coiled spring capable of expansion and contraction, said first electrode having one end thereof connected to a first conductor disposed on a fixed insulating member of said sensor and the other end thereof connected to a movable insulating member of said sensor; and

a second electrode connected at one end thereof to a second conductor disposed on said fixed insulating member of said sensor and positioned opposite to said first electrode without contacting the same;

whereby capacitance between said first and second electrodes varies in response to the expansion or contraction of said electrically conductive coiled spring, and

wherein said sensor further comprises a built-in printed circuit board, and said first and second conductors disposed on said fixed insulating member of said sensor are mounted on said printed circuit board.