GB2117566A

GB2117566A - Switch, especially for cooling devices

Info

Publication number: GB2117566A
Application number: GB8207742A
Authority: GB
Inventors: Tibor Sinka; Andras Vida
Original assignee: Hutogepgyar
Current assignee: Hutogepgyar
Priority date: 1982-03-20
Filing date: 1982-03-17
Publication date: 1983-10-12
Also published as: SE8201656L; LU84229A1; DE3210390C2; CH658542A5; FR2530003A1; DE3210390A1; FR2530003B1; GB2117566B; SE457185B

Abstract

A switch especially for controlling a refrigerator which can equally be operated from an electric mains, a storage battery and a source of propane-butane gas, has a shaft 3,8 journalled in a housing 5 and provided with cams 1 for actuating electrical microswitches 6 which control the electrical circuits supplying the electrical power. In a given angular position of the shaft 3, it is axially movable for actuating a gas supply valve 4. The microswitches 6 are isolated from each other by partition walls of the housing 5. <IMAGE>

Description

SPECIFICATION Mode-selecting and interlock switch especially for cooling devices The invention concerns mode-selecting and interlocking switches which may very advantageously be utilised for cooling machines which may be operated electrically as well as by gas, such as propane-butane gas.

It is known that absorption-type refrigerators are frequently used in motor vehicles, or in their trailers, in which, in dependence on the oeprating conditions of the vehicle, one or other of the above-mentioned modes of opera-tion (or sources of power) is utilised.

In these combined absorption-type refrigerators, which may for instance be operated electrically utilising 220V (mains voltage) or 1 2V (from a storage battery) or by propanebutane gas, the mutual exclusion and interlocking of the different modes of operation is not satisfactorily solved. This means that there is a risk or possibility for the accidental switching-on of two or possibly all three modes of operation at the same time, which may seriously damage the apparatus.

To avoid such an eventuality, it is desired to produce mode-selecting switches in a socalled 'interlock' embodiment.

Several solutions are known to satisfy this requirement and they operate by combining electrical and mechanical interlocking but in a rather complicated manner.

To develop satisfactory interlocking for refrigerators or groups of cooling machines two trends in development are currently known. In one trend of development, the 220V and the 1 2V circuits can be switched by a switch common to both which only permits one of the circuits at any one time to be operational.

In this case, however, the possibility exists of switching on one of the electrical circuits at the same time as the gas circuit.

This is the main disadvantage of this trend.

The essence of the other trend of development is that the button or knob of the electrical regulator or the gas heat regulator is so formed that any angular displacement of one interlocks the other. A disadvantage of this solution is that it is quite difficult to assure the location of the two buttons in each other's vicinity. In the most modern current construction a combined gas electric thermostat is utilised which has only one operating knob or button and which therefore makes such a solution inherently impossible.

One aim of the present invention is to eliminate or reduce the disadvantages of known solutions and to provide a mode-selecting switch which can be produced with relatively low technical investment and which simply and greatly reliably solves the switching of the operating mode by means of a single interlockable element.

This aim is sought to be satisfied in accordance with the invention by means of a modeselecting and interlocking switch with which switching can be reliably and safely effected between mains voltage, an accumulator or storage battery or a gas network. This switch may be characterised in that it has a shaft journalled in a common housing and the shaft is provided with cams. This carnmed shaft is in controlling connection with electrical switches, expediently microswitches. In a given postion of the shaft it is secured against angular displacement. In such a postion, in which angular displacement is prevented, the shaft has a degree of freedom for axial movement relative to the housing. One end of the shaft is provided with a hand-operable knob or button while its other end is connectible with a gas switch.Expediently, the gas switch is formed as an electromagnetic safety switch.

A preferred embodiment of the present invention will be described with reference to the accompanying somewhat schematic drawing which illustrates a mode-selecting and interlocking switch according to the invention in an "exploded" view.

As may be seen from the drawing a shaft 3 is journalled in the same housing 5 as a gas switch 4. A pipe 8 is pulled over the shaft 3 so as to prevent relative movement therebetween. The pipe 8 is provided ith cams 1 integrally formed on its outer surface. The cams 1 are in controlling connection with switches 6 which in the preferred embodiment are microswitches. These switches 6 can interrupt circuits, as required, in one or two phases. In a given position of the cams 1 all the switches are in the "0" or "off" position.

One end of the shaft 3 is provided with one or more flat surfaces. These fit into a recess or cut-out in the housing 5 in the given angular position of the shaft 3 in such a manner that in that position the shaft 3 has a degree of freedom of movement in the axial direction only. This is required to ensure that when the operating knob 7 of the shaft 3 is pressed axially, the electrical switching modes or possibilities are interlocked and in this position the gas switch 4 connected to the shaft 3 by way of nuts 2 can be activated via the shaft 3. Expediently, the gas switch 4 is formed as a per se known electromagnetic safety valve.

The mode-selecting and interlocking switch according to the invention may also be realised in such a form that the cams 1 are separately formed on the outer surfaces of respective rings and the shaft 3 is a splined shaft. Spacing elements may be positioned between the rings. An advantage of this embodiment is that any desired switching mode can be achieved in this way but its disadvantage is that the construction is more complicated.

To ensure that the person effecting the switching should be quite certain that a given switching position has been attained, it may expediently be necessary to provide orienting and fixing mechanisms which are resiliently biased towards angular positions corresponding to desired switching positions.

The mutual positions of the above-mentioned microswitches are ensured by the partition walls of the housing 5, in the illustrated embodiment. However, a switch according to the invention may also be constructed wherein the fixing and positioning of the microswitches is effected by the snapping together of the housing 5 and a housing cover which may have, in a manner known per se, snapping tongues and lugs.

Thus the above-mentioned microswitches 6 connected to electrical circuits need only be placed in the appropriate sequence in the housing 5 and then, following snapping in of the lid, no further fixing operations are required to be performed.

The mode-selecting and interlocking switch according to the invention may be used in areas of application beyond cooling machines and its utilisation is advantageous in any other area posing similar technical problems.

Claims

1. A mode-selecting and interlocking switch, expediently for cooling apparatus operable by different sources of power, said switch being settable between a plurality of settings, e.g. mains voltage, battery voltage and gas power source settings and comprising a shaft journalled in a housing and provided with cams co-operable with electrical switch contacts for making the circuits supplying electrical power, said shaft being secured agains angular displacement in a predetermined orientation thereof in which there exists one degree of freedom of movement in an axial direction between the housing and the shaft, the said shaft being provided with an actuating member for effecting displacement of said shaft, and an end of said shaft is connectible with a gas supply switch.

2. A switch according to claim 1, wherein the cams are formed on a pipe or sleeve disposed on the shaft.

3. A switch according to claim 1, wherein the cams are provided on respective rings on the shaft, the rings being kept apart by the interposition of spacing elements.

4. A switch according to any preceding claim, wherein in addition to the operative positions, the switch is also provided with a position in which all modes of operation (sources of power) are switched off (interrupted).

5. A switch according to any preceding claim, wherein the angular positions of the shaft corresponding to the different switching positions are determined by a sprung locating and securing mechanism.

6. A switch according to any preceding claim, wherein the electrical switch contacts are mutually spaced apart and insulated from each other by partition walls of the housing.

7. A switch according to any of claims 1 to 5, wherein the fixing and positioning of the electrical switch contacts is effected by the cooperation of the housing and its lid when they are secured together.

8. A switch according to claim 7, wherein the housing and its lid are fixed together by snap-in tongues.

9. A switch substantially as herein described with reference to and as shown in the accompanying drawings.