Liquid level gauge

• US 4,981,039 A
• Filed: 07/05/1989
• Issued: 01/01/1991
• Est. Priority Date: 07/07/1988
• Status: Expired due to Fees

• Current Assignee: Toyoda Gosei Company Limited 1 Nagahata Ochiai Haruhi-Cho Nishikasugai-Gun Aichi-Ken Japan
• Original Assignee: Toyoda Gosei Company Limited (Toyota Motor Corporation)
• Inventors: Takahashi, Toshinori, Kawai, Makoto, Kikuta, Mitsuhiro, Hayashi, Chikahisa
• Primary Examiner(s): Yasich, Daniel M.
• Application Number:
  US07/375,671
• Time in Patent Office: 545 Days
• Field of Search: 73/292, 73/308, 374/142, 374/165, 340/623, 340/449, 340/450, 200/84 C, 337/207
• US Class Current: 73/292
• CPC Class Codes: G01F 23/74 for sensing changes in level only at discrete points
• CPC Class Codes: G01K 13/10 for measuring temperature within piled or stacked materials by special arrangements for conducting heat from the object to the sensitive heat element G01K1/16
• CPC Class Codes: H01H 36/02 actuated by movement of a float carrying a magnet

Abstract

A gauge for detecting both the temperature and surface level of a fluid within a container. The gauge includes an elongated casing which extends into the fluid. A float which rises and falls with the fluid surface is slidably coupled to the casing and carries a magnet. A support member positioned within the casing carries both a sensor for determining the position of the magnet and a sensor for measuring the fluid temperature. The surface level of the fluid can be determined from the position of the magnet. A heat conducting element thermally couples the temperature detecting sensor to the fluid. In a preferred embodiment, the support member takes the form of a printed board. In a separate preferred aspect, the temperature and magnet detecting sensors are reed switches which are vertically spaced apart yet aligned in parallel to minimize interference.

Claims

1. A liquid level gauge for detecting a surface level of a fluid disposed within a container, the liquid level gauge comprising:

an elongated gauge casing carried by the container and extending into the fluid such that it crosses a surface of the fluid;

a float slidably coupled to said elongated gauge casing and arranged to rise and fall with the surface level of the fluid;

a magnet mounted on said float such that it rises and falls with the float;

magnet detecting means for detecting a position of said magnet;

heat sensitive means, disposed in the casing, for detecting an amount of heat of the fluid;

heat conducting means for thermally coupling the fluid to said heat sensitive means, said heat conducting means having a heat conductivity higher than a heat conductivity of said elongated gauge casing; and

a detector support member disposed within said casing, wherein said heat sensitive means, said magnet detecting means, and at least a portion of said heat conducting means are attached to said detector support member.

2. A liquid level gauge according to claim 1 wherein said heat conducting means includes:

a first portion exposed outside of said casing and extending into the fluid; and

a second portion disposed within said casing and connected with said temperature detecting means.

3. A liquid level gauge according to claim 1 wherein:

said magnet detecting means and said heat sensitive means each include elongated sensing elements that are arranged in parallel and are vertically, spaced apart with the magnet detecting means being positioned above the heat sensitive means;

said float has a length at least as long as a vertical distance between said heat sensitive means and said magnet detecting means; and

said magnet is attached to the upper portion of said float.

4. A liquid level gauge according to claim 3 wherein said float has a larger diameter towards a bottom portion of the container and said magnet is attached to an upper portion of the float.

5. A liquid level gauge according to claim 3 wherein said elongated sensing elements are reed switches.

6. A liquid level gauge according to claim 1 wherein the detector support member is a printed board.

7. A liquid level gauge for detecting a surface level of a fluid disposed within a container, the liquid level gauge comprising:

an elongated gauge casing carried by the container and extending into the fluid such that it crosses a surface of the fluid;

a float slidably coupled to said elongated gauge casing and longitudinally movably engaged with the casing;

a magnet mounted on said float such that it rises and falls with the float;

magnet detecting means for detecting a position of said magnet;

heat sensitive means for detecting an amount of heat of the fluid;

heat conducting means for conducting heat, thermally connected with said heat sensitive means, said heat conducting means having a heat conductivity higher than a heat conductivity of said elongated gauge casing; and

a printed board provided in said casing, said magnetism detecting means and said heat sensitive means being attached to said printed board.

8. A liquid level gauge according to claim 7 wherein said heat conducting means is attached to the lower end of said casing and seals the lower end of said casing, and includes a float stopper that prevents said float from sliding off said casing.

9. A liquid level gauge according to claim 7 wherein said heat conducting means includes;

a heat conducting member made of synthetic resin mixed with metallic powder and integrally formed at the lower end of said casing.

10. A liquid level gauge according to claim 7 wherein said heat conducting means includes;

a conductive foil formed at the lower end of said printed board.

11. A liquid level gauge according to claim 7 wherein said heat conducting means includes;

a heat conducting plate mounted at the lower end of said printed board by a rivet.

12. A liquid level gauge according to claim 7 wherein said heat conducting means includes a heat conducting segment coupled to the lower end of said printed board.

13. A liquid level gauge according to claim 7 wherein:

the lower end of said printed board protrudes from the lower end of said casing; and

said heat conducting means includes a heat conducting block attached to the lower end of said printed board.

14. A liquid level gauge for detecting a surface level of a fluid disposed within a container, the liquid level gauge comprising:

an elongated gauge casing carried by the container and extending into the fluid such that it crosses a surface of the fluid;

a float slidably coupled to said elongated gauge casing and longitudinally movably engaged with the casing;

a magnet mounted on said float such that it rises and falls with the float;

magnet detecting means for detecting a position of said magnet;

temperature detecting means for detecting a temperature of the fluid;

heat conducting means for conducting heat, thermally connected with said temperature detecting means, said heat conducting means having a heat conductivity higher than a heat conductivity of said elongated gauge casing; and

said magnet detecting means and said temperature detecting means each include elongated sensing elements that are arranged in parallel and are vertically spaced apart with the magnet detecting means being positioned above the temperature detecting means;

said float has a length at least as long as a vertical distance between said temperature detecting means and said magnet detecting means; and

said magnet is attached to the upper portion of said float;

and further comprising a magnet supporting member attached to the upper end of said float and wherein said magnet is attached to the upper end of said magnet supporting member.

15. A liquid level gauge according to claim 14 wherein said float and said magnet supporting member are formed integrally.

16. A liquid level gauge according to claim 14 wherein:

said float has an internal thread on an inner surface thereof;

said magnet supporting member has an external thread on an outer surface corresponding to said internal thread; and

a length of said magnet supporting member protrudes from said float and is adjustable by adjusting the amount of screwing of said external thread to said internal thread.

17. A liquid level gauge according to claim 14 further comprising:

a printed board provided in said casing, wherein said magnet detecting means and said temperature detecting means are attached to said printed board.

18. A liquid level gauge according to claim 17 wherein

said heat conducting means includes a conductive foil formed at the lower end of said printed board.

19. A liquid level gauge according to claim 17 wherein

said heat conducting means includes a heat conducting member made of synthetic resin mixed with metallic powder and is integrally formed at the lower end of said casing.

20. A gauge for detecting a surface level and temperature of a fluid within a container, the gauge comprising:

an elongated gauge casing carried by the container and extending into the fluid such that it crosses the surface of the fluid;

a float slidably coupled to the casing and arranged to rise and fall with the surface level of the fluid;

a magnet mounted on said float such that it rises and falls with the float;

heat sensitive means for detecting an amount of heat of the fluid;

means for detecting the position of the magnet; and

a printed board provided in said casing, said magnet detecting means and said heat sensitive means being attached to said printed board.