Title:
LEVEL SENSITIVE SWITCH
United States Patent 3809842


Abstract:
A level sensitive switch comprised of a body member having a closed loop flow channel filled with two immiscible liquids, one being electrically conductive and the other being electrically non-conductive. First terminals are mounted in the body and have ends extending into the channel at opposite ends thereof and are adjustable in relation to the level of the conductive fluid and a second terminal is mounted in the body member and has an end in electrical contact with the conductive liquid whereby tilting of the body member effects an electrical circuit between a first terminal and the second terminal. The speed of the liquid movement through the channel is adjustable by a dampening apparatus associated with the channel. An expansion chamber communicates with the channel and compensates for volume changes of the liquid to assure that the channel is maintained full of the liquids.



Inventors:
SLUSHER E
Application Number:
05/336037
Publication Date:
05/07/1974
Filing Date:
02/26/1973
Assignee:
HYDRAL LADDER INC,US
Primary Class:
Other Classes:
200/190
International Classes:
H01H29/20; (IPC1-7): H01H29/00
Field of Search:
200/220,221,231,190,186
View Patent Images:
US Patent References:
3030477Position sensitive liquid conductor switch1962-04-17Hensley
2275011Inertia switch1942-03-03Erich
2088718Refrigerating apparatus1937-08-03Philipp
1638814Electrical pressure gauge1927-08-09Epstein
1600121Mercury stabilizer for aeroplanes, airships, and other aircraft1926-09-14Mazade



Primary Examiner:
Hohauser, Herman
Attorney, Agent or Firm:
Fishburn, Gold & Litman
Claims:
1. A level sensitive switch comprising:

2. A level sensitive switch as set forth in claim 1 including:

3. A level sensitive switch as set forth in claim 2 wherein:

4. A level sensitive switch as set forth in claim 3 wherein:

5. A level sensitive switch comprising:

Description:
The principal objects of the present invention are: to provide a switch with liquid filled channels and that is sensitive to a change in level to complete an electrical circuit when tilted to a non-level position; to provide such a switch that will activate an alarm if a structure on which it is placed moves to a non-level position; to provide such a switch with channels wherein the liquids filling same are immiscible and have different densities wherein one of the liquids is positioned above the other liquid with one liquid being non-conductive and the other liquid being conductive wherein an electrical circuit is formed by the conductive liquid contacting circuit terminals; to provide such a switch with means to adjust the sensitivity thereof to level changes to actuate the switch; to provide such a switch with externally adjustable means to dampen the liquid flow rate through the channels containing same, the flow being induced by tilting of the switch; to provide such a switch with an expansion chamber to compensate for volume changes of the liquids thereby maintaining a substantially constant level of liquids therein; and to provide such a switch that is adapted for its intended use, easy and inexpensive to manufacture, positive in operation and easy to use.

Other objects and advantages of the present invention will become apparent from the following description taken in connection with the accompanying drawings wherein are set forth by way of illustration and example certain embodiments of this invention.

FIG. 1 is a perspective view of a level sensitive switch with portions broken away to show details thereof.

FIG. 2 is a sectioned view of the switch taken along the line 2--2, FIG. 1.

FIG. 3 is a section view of a portion of the switch taken along the line 3--3, FIG. 2.

FIG. 4 is a section view of a portion of the switch taken along the line 4--4, FIG. 2.

As required, detailed embodiments of the present invention are disclosed herein. However, it is to be understood that the disclosed embodiments are merely exemplary of the invention which may be embodied in various forms. Therefore, specific structural and functional details disclosed herein are not to be interpreted as limiting, but merely as a basis for the claims and as a representative basis for teaching one skilled in the art to variously employ the present invention in virtually any appropriate detailed structure.

Referring more in detail to the drawings:

The reference numeral 1 designates generally a level sensitive switch having a body structure 2 with a closed loop flow channel 3 that is filled with two immiscible liquids 4 and 5 having interfaces therebetween with the liquid 4 preferably being non-conductive and the liquid 5 preferably being conductive. The switch is arranged for use in an electrical circuit with terminals having portions extending into the channel relative to the conductive liquid whereby a predetermined tilt completes the circuit. In the structure illustrated, circuit terminals 6 and 7 are mounted in the body structure 2 having lower ends 8 and 9 respectively in spaced relation to the level of the conductive liquid 5. Circuit terminals 10 and 11 are mounted in the body structure 2 having ends 12 and 13 respectively in electrical contact with the conductive liquid 5 whereby tilting of the body structure 2 causes the conductive liquid 5 to form an electric circuit between a terminal 10 or 11 and a terminal 6 or 7. Dampening means 15 are associated with the channel 3 and are operable to selectively adjust the flow rate of the liquids 4 and 5 within the channel 3, the movement of the liquids 4 and 5 being induced by tilting of the body structure 2.

The body structure 2 may be a single unit with all of the channels arranged therein or with variations wherein there are a plurality of parts assembled to provide the closed loop and mounting of terminals for desired adjustment and control. In the structure illustrated, the body structure 2 includes body members 16 and 17 positioned and secured in spaced apart relation and as illustrated by rigid members such as plate members 18 and 19 extend therebetween and secured thereto by fasteners 20 such as recessed screws. The rigid connectors may be secured to any portions of the body members 16 and 17 and for convenience of manufacture the plate 18 partially overlies the upper surfaces of the body members 16 and 17 and the plate 19 overlies the bottom surfaces of the body members 16 and 17. The body members 16 and 17 may be opaque, but it is preferable that each be made of a transparent plastic material and have therein an upstanding or vertical chamber 21 and 22 respectively. The chambers 21 and 22 are connected together by passages to form a loop flow channel for the movement of the liquids 4 and 5 therein between the chambers 21 and 22. In the illustrated structure, conduits extend therebetween one between upper portions of the chambers 21 and 22 and one between lower portions of the chambers 21 and 22. Preferably, upper and lower passages 23 and 24 respectively extend outwardly from the chamber 21 generally toward the body member 17 with the upper passage 23 inclined upwardly and the lower passage 24 inclined downwardly. Upper and lower passages 25 and 26 respectively open into the chamber 22 and extend outwardly therefrom generally toward the body member 16 with the upper passage 25 inclined upwardly and the lower passage 26 inclined downwardly. A tubular member 27 extends into the passages 23 and 25 and is secured therein in sealed relation forming an upper disposed flow channel between the chambers 21 and 22. Preferably, the tubular member 27 is flexible and extends upwardly and over a support member 28 whereby the member 28 supports same and the tubular member 27 is in an inverted V-shape. A tubular member 30 extends into the passages 24 and 26 and is secured therein in sealed relation connecting the chambers 21 and 22 forming a lower disposed flow channel whereby the closed loop flow channel 3 is formed. Preferably, the tubular member 30 is rigid and is shaped so as to prevent the collection of bubbles therein and as illustrated is in the form of an upwardly curved or V-shape.

The body member 16, as illustrated, has a threaded opening 31 opening into the chamber 21 providing access thereto for filling the channel 3 with the liquids 4 and 5. A plug 32 threads into the opening 31 for sealing same after the channel 3 is filled. As illustrated, the terminals 6, 7, 10 and 11 are elongate members each being in suitable adjustable engagement with the respective body members 16 and 17 whereby the position of the ends 8, 9, 12 and 13 are adjustable in relation to the liquid 5. In the form illustrated, the terminals 6, 7, 10 and 11 are threaded and are in threaded engagement with the body members 16 and 17 whereby movement of the terminals is accomplished by rotating same. It is particularly desirable to have the terminals 6 and 7 adjustable so that the ends 8 and 9 may be selectively spaced from the surface of the liquid 5 in the chambers 21 and 22 so as to adjust the sensitivity of the level sensitive switch 1 to control the amount of tilt necessary to move the liquid 5 into contact with the terminals 6 and 7. The terminals 6, 7, 10 and 11 are each provided with a lock-nut 33, 34, 35 and 36 respectively to hold the terminals in the selected positions. Each of the terminals 6, 7, 10 and 11 are provided with integral collars 37, 38, 39 and 40 respectively and terminal nuts 41, 42, 43 and 44 respectively wherein the collars 37, 38, 39 and 40 provide grasping means for adjusting the terminals and the nuts 41, 42, 43 and 44 are used for securing an electrical lead to each terminal.

A seal is provided between the terminals 6, 7, 10 and 11 and the respective body members 16 and 17 to prevent leakage of the liquids 4 and 5. Any suitable seal means such as gaskets, O-rings and the like can be used. Also, the material of the body members 16 and 17 can be of a type that will form a seal with the terminals 6, 7, 10 and 11 by engagement therewith. The liquid 4 can be of a high viscosity to help prevent leaking or can be an anti-leak anti-freeze that would help provide a seal between the body members and the respective terminals. Non-conductive liquids such as glycol, ethyleneglycol and glycerol also can be used for the liquid 4. The liquid 5 as described above is conductive having a density greater than the liquid 4 and may be a liquid having conductive material suspended therein or any suitable electrolyte and preferably is mercury.

The dampening means 15 are associated with the loop channel 3 and are operable to retard movement of the liquids 4 and 5 therein for controlling the time sensitivity of switch 1. It is desirable to retard movement of the liquids 4 and 5 to make the switch 1 less susceptible to jolts and shocks and to reduce hunting for a level position of the liquids. The dampening means 15 can be any suitable device such as a valve to restrict the flow of liquids in a conduit and is preferably adjustable. In the illustrated structure the dampening means 15 includes a support member 46 secured to the plate 18 and having an elongate bore 47 extending partially therethrough with an elongate threaded shaft 48 mounted therein. Preferably, the shaft 48 is prevented from rotating in the bore 47 by suitable means. A threaded collar 49 is threadably mounted on the shaft 48 and is positioned between two opposed surfaces partially defining a generally rectangular aperture through the support member 46. Relative rotation between the collar 49 and shaft 48 urges movement of the shaft 48 up and down within the bore 47. The tubular member 27 extends through an opening 52 adjacent the lower end of the support member 46 wherein an end 53 of the shaft 48 will engage and compress same in response to relative rotation between the collar 49 and shaft 48 thereby decreasing the area of the interior of the tubular member 27 to restrict the movement of the fluid 4 therethrough thereby dampening the movement of the liquids 4 and 5 induced by tilting of the switch 1.

An expansion chamber 55 communicates with the loop channel 3 to compensate for expansion and contraction of the liquids 4 and 5 and maintain the loop channel 3 full of liquids at a relatively constant pressure.

In the illustrated structure, the expansion chamber 55 is in the body member 17 and opens into the chamber 22. A resilient member such as a flexible sac 56 that is filled with gas and is enclosed in the chamber 55 wherein a plug 57 seals the chamber 55 from the atmosphere and as illustrated, the plug 57 is threaded and is in engagement with a threaded portion of the chamber 55. Upon expansion and contraction of the liquids 4 and 5, the gas contained in the sac 56 contracts and expands respectively compensating for the volume change of the liquids 4 and 5. The sac 56 prevents the gas therein from entering the flow channel 3.

It is to be noted that the tubular members 27 and 30 may have T-members (not shown) connected thereto as at 61 and 62 respectively for joining two switches 1 together with the liquid 4 and 5 flowing between the two switches 1.

In operation, the switch 1 is filled with the liquids 4 and 5 and is placed on a level surface to adjust the spacing between the terminal ends 8 and 9 and the liquid 4. The transparent bodies 16 and 17 provide for visual observation of the adjusting procedure to facilitate same. The greater the spacing the more tilt required to form an electrical circuit thereby decreasing the sensitivity of the switch 1. The terminals 6 and 7 and at least one of the terminals 10 and 11 are connected to a warning device (not shown) whereby when a circuit is formed between a terminal 10 or 11 and a terminal 6 or 7 the warning device will be activated. The use of four terminals makes the switch more versatile in connection into combinations of circuitry for controls. The switch 1 is placed on a structure such as a beam suspended from a crane and if it moves sufficiently out of level the switch 1 and warning device will warn that the structure is not level and appropriate corrections can be made. Movement of the liquids in one of the chambers 21 and 22 results in proportional movement of the liquids in the other chamber whereby the interfaces between the liquids 4 and 5 are maintained in a level plane.

It is to be understood that while I have illustrated and described certain forms of my invention, it is not to be limited to the specific arrangement of parts illustrated and described herein.