GB2134729A

GB2134729A - A switch apparatus for controlling the power supply to electrical apparatus

Info

Publication number: GB2134729A
Application number: GB08328719A
Authority: GB
Inventors: Alfred Maisner; Erwin Potthof; Tilman Kruger; Manfred Barwig
Original assignee: Diehl GmbH and Co
Current assignee: Diehl Verwaltungs Stiftung
Priority date: 1982-11-03
Filing date: 1983-10-27
Publication date: 1984-08-15
Also published as: DE3240547A1; DE3240547C2; IT8323402V0; GB2134729B; GB8328719D0; FR2535569A1; IT8323512A0; IT1169634B; FR2535569B1

Abstract

A rotary coding switch 1 provides an n-bit output code to a decoding circuit 15 which operates a power switch 17 to control the power applied to a load 21, such as an electric stove, in dependence on the position of switch 1, the switch 1 having an additional position 13 providing a control signal for switch 17 via a line 22 bypassing the decoding circuit 15. The additional switch position may provide full power to the load 21. Alternatively, the circuit 15 may control a plurality of switches 17 each connected to a respective part of the load 21, the direct line 22 controlling only one of the switches 17. Switch 17 may be a monostable relay or a bistable, bipolar relay (Fig. 4). <IMAGE>

Description

SPECIFICATION A switch apparatus for controlling the power supply to electrical apparatus The invention relates to switch apparatus, for controlling the power supply to electrical power consuming apparatus (e.g. an electric stove having resistive heating elements), of the kind having a manually operable coding switchproviding an n-bit output code to a decoding power control circuit which actuates a controllable power switch to make available power, quantized according to the output code of the coding switch, for the electrical apparatus.

In our German Offenlegungsschrift No.

28 48 824 (from which German Application our GB 2036441A is derived), we disclose switch apparatus for controlling the power of electricity consuming ohmic devices in which a rotary coding switch controls by a four bit code a decoding power control circuit. With such a rotary coding switch, accordingly 24=16 different switching positions giving different four bit output code words are possible. One of these switching positions, with which one code word, preferably the code word 0000, is associated, is in the case of this rotary coding switch, however, reached not by rotating, but by pulling the switch actuator, and causes the decoding power control circuit to initiate a power boost to the ohmic device for a heating-up operation.In this switch apparatus each of every one of the switching positions of the rotary coding switch provides a specific code word associated with a respective one of all the power supply quantum levels for the electricity consuming device, so that for example also the highest power supply level is possible only by way of the selection of an appropriate code word to control the decoding power control circuit. This has the disadvantage that in the event of a failure of the decoding power control circuit, the entire switch apparatus is incapable of functioning to supply power to the electricity consuming device.

An object of the present invention is to provide improved switching apparatus, of the kind mentioned at the beginning thereof, which retains advantages of our known switch apparatus but which overcomes said disadvantage.

According to the present invention there is provided switch apparatus, for controlling the power supply to electrical consuming device (such as a resistive heating device of an electric stove), comprising a manually-actuable rotary coding switch actuable to provide an n-bit output code; a controllable power switch; and a decoding power control circuit which is arranged to control the power switch to make available power, quantized according to the output code of the rotary coding switch, for an electrical power consuming device, characterised in that the rotary coding switch has an additional switching position, which position is provided with at least one additional switching contact connected to the controllable power switch by bridging means bridging the decoding power control circuit, to actuate the power switch in such a way that a predetermined electrical power level is provided for an electrical power consuming device.

The switch apparatus of the invention enables an electrical apparatus, such as an electric stove, to be used in a practical manner even in the event of a failure of essential electronic parts of the control circuit, until such time as appropriate repair measures can be taken.

Thus, the rotary coding switch can provide a range of up to 2n+ 1 discrete rotary switching positions comprising the output code switching positions plus the additional switching position. In the additional switching position of the rotary coding switch, maximum electrical power may be made available to the electrical power consuming device. Thus, for example in the case of a rotary coding switch with three bits of resolution, giving a maximum of eight three bit output code words, partial power can be supplied at eight different quantized levels or stages, whilst the additional switching position serves as a ninth power supply in which full power is supplied.This is also particularly advantageous for the indication of the various power stages by means of a one-figure numerical display, because all the ten possible numerical display variants, in which the numeral 0 corresponds to "off" position and the numerals 1 to 9 represent discrete power levels, can be fully utilised.

For actuation of the additional switching contact in the additional switching position in an advantageous manner a further control cam may be mounted on an axis of rotation of the rotary coding switch, which cam exclusively actuates the additional switching contact. The provision of such a cam enables a particularly simple development of a conventional rotary coding switch to be provided, in which switch a respective individual cam switch is provided for each bit, together with a respective cam for each cam switch as well as for the additional switching contact.

Furthermore, any of various relays, such as monostable relays or bistable relays with an electronic relay control circuit, may be employed in the switch apparatus in accordance with the invention in an extremely simple way. The bridg ing means is preferably arranged so that in the additional switching position, in the case in which a bistable relay is to be switched on, the relay control circuit is also bridged.

The invention will be described further, by way of example, with reference to the accompanying drawings, wherein Figure 1 shows a schematic representation of an exemplified embodiment of a rotary coding switch with an additional switching position; Figure 2 shows a basic circuit diagram of an embcdiment of switch apparatus of the invention incorporating a rotary coding switch as shown in Figure 1; Figure 3 shows a further exemplified embodiment of switch apparatus with a cam switch form of rotary coding switch; Figure 4 shows parts of a further exemplified embodiment of switch apparatus using a bistable relay.

The rotary coding switch 1 shown schematically in Figure 1 has four centricallyarranged annular or partially annular contact structures. These contact structures are wiped by contacts 4 on a contact bridge 3, fastened to a rotatable shaft 2 arranged in the centre of the contact structures. The sliding contacts 4 are connected to one another electrically. The contact structures consist, in this embodiment, of an inner contact ring 5, which serves for the current supply, and the three outer contact structures 6 serve as code contacts which receive, by way of the contact bridge 3, the current, supplied by way of the contact ring 5, in a predetermined sequence which is dependent upon the position of the contact bridge 3. The code contacts 6 are subdivisible over an angle of 3600 into ten segments, which are designated by the numbers I to IX and the designation "off".In this exemplified embodiment the following codes are associated with the sectors I to VIII: I corresponds to the code word 000 II corresponds to the code word 100 Ill corresponds to the code word 110 IV corresponds to the code word 111 V corresponds to the code word 101 VI corresponds to the code word 001 VII corresponds to the code word 01 1 VIII corresponds to the code word 010 In the above list, the sequence of the individual bits in each of the code words corresponds to the positional sequence of the code contacts 6 from the inside outwardly. In each code word designation has been effected by "1" when in the corresponding sector the respective code contact 6 is electrically connected by the contact bridge 3 to the inner contact ring 5 and by "0" when the code contact is not so connected.In the "off" sector, which is arranged between the sectors IX and I, the connections 7 of the contact ring 5 and of the code contacts 6 are conducted outwardly e.g. to terminals. In sector IX, which corresponds to the additional switching position (the additional switching position will be referred to hereinafter as the position IX), there is disposed an additional switching contact 8, designed as a contact strip, with a connection 9 of its own, which is insulated electrically from the remaining contact structures 6, 7. The additional switching contact 8 is supplied with current by the contact bridge 3 when this is rotated into sector IX, in other words into the additional switching position IX. In the present exemplified embodiment, this contact strip 8 lies in such a way that it is touched by the outermost sliding contact 4 of the contact bridge 3.

Upon rotation of the contact bridge 3 into the "off" sector, in this exemplified embodiment, the contacting between the contact bridge 3 and the contact structures is not relevant, since in this position the total current supply of the switch apparatus is intended to be switched off, for example, by a switch (which is not shown for reasons of clarity) actuable by a control cam fastened to the shaft 2.

It is of course, possible to arrange the contact structures 6, 7 so that a different exploring code sequence arises or to increase the number of code contacts 6 (for example to give a 4-bit code), to give a correspondingly greater number of switching positions. In switch apparatus of the invention there is the important feature that one of the switching positions of the rotary coding switch provides an additional possibility for closing a contact separately from the code contacts as is realised in the above exemplified embodiment as a result of the additional switching contact 8, designed as a contact strip, in conjunction with the contact bridge 3 for the additional switching position IX.The additional switching position can be arranged in any desired manner between the other switching positions, but should preferably be so arranged that it fits with respect to its function (i.e. the power level or stage it controls) between the functions (i.e.

power levels or stages) controlled by the adjacent switching positions.

The following exemplified embodiments, are based on a rotary coding switch 1 having three bits of resolution. It is, of course, here also possible to achieve a higher number of switching steps by using rotary coding switches 1 having higher resolution. Figure 2 shows a basic circuit diagram of switch apparatus in accordance with the invention with a symbolically-represented rotary coding switch 1, which may be constructed for example as described with regard to Figure 1.

The code contacts 6 of the rotary coding switch 1 are shown in Figure 2 as contacts of make and break construction code switches 10, 11 and 12, in which respect one of these switches 10, 11, 12, for example switch 12, is a change-over switch, e.g. a two way switch, and has an additional switching contact 13 which is designed as a change-over contact and which corresponds to the contact strip 8 in accordance with Figure 1.

The rotary coding switch 1 controls by way of three control lines 14, in accordance with the position combination of the switches 10, 11, 12, a decoding power control circuit 15, in that the switches 10, 11, 1 2 connect the respective control line 14 to a voltage U, which can be for example also an operating voltage UB of a decoding power control circuit 1 5. The decoding power control circuit 1 5 generates, at a timing ouput 1 6, a binary control voltage for a controllable power switch 17. This control voltage consists of a timed direct voltage, for example the operating voltage UB, in which respect the timing ratio and possibly also the frequency of this control voltage is dependent upon the code word signal combination applied via the control lines 1 4 to the decoding power control circuit 1 5. The controllable power switch 1 7 consists, in this exemplified embodiment in accordance with Figure 2, of a monostable relay 18, the switching contacts 19 of which in turn switch a power supply voltage, for example the mains power voltage, onto an electrical power consuming device 21, such as a heating device of an electric stove.Bridging means, comprising a direct control line 22, connects the additional change-over 13 of the rotary coding switch 1 directly with an exciting winding 20 of the monostable relay 18, thereby circumventing the decoding power control circuit 15, to apply a suitable control voltage U (for example the same as the operating voltage UB of the decoding power control circuit 15) so that, in the additional switching position IX of the rotary coding switch 1 5 in which the additional change-over contact 13 is connected to the control voltage U, the monostable relay 18 is switched through and the electrical power consuming device 21 is connected by the switching contacts 19 to its power supply voltage.

As a result of this meansure, thus the device 21 can, even in the event of a failure of the decoding power control circuit 15, still be switched on and off, so that an at least restricted utilisation of the apparatus is made possible.

If the device 21 consists of several partial power consuming units which are controlled, for example for redundancy reasons, by way of several relays 18, then the direct control line 22 can also control only one part of the relays 18, so that only a part or unit of the device 21 is supplied with power voltage. In the additional switching position IX of the rotary coding switch 1, then thus also only a partial power of the device 21 would be switched on, in which respect then the additional switching position IX in the rotary coding switch 1 should preferably be arranged in a different suitable sector appropriate to the partial power level. This development of the apparatus in accordance with the invention can be used in an advantageous manner in the case of electric stoves in which in certain circumstances a permanent operation with full power can involve risks e.g. for the user.

Figure 3 shows a further exemplified embodiment of switch apparatus with a schematically-represented rotary codiny switch 1, which is here designed as a cam switch comprising a rotary shaft 2', a rotary knob 23 connected in force-locking manner to the shaft 2' and four control cams 24 to 27 which are fastened to the shaft 2', each of which cams serves to actuate a respective one of the switches 28 to 31 of make and break form.Three of the control cams 24 to 26 are so finish-shaped that the switches 28 to 30 actuated by them serve as code switches to generate a switching-positiondependent three bit word or pattern output at the code contacts 6, which output code controls the decoding power control circuit with a voltage U by way of the control lines 14, in the same way as in the case of the exemplified embodiment in accordance with Figure 2, and which output code corresponds for example to the code described hereinbefore with reference to Figure 1. The fourth control cam 27 actuates its associated switch 31 in the additional switching position IX of the rotary coding switch 1, with which switching position IX no specific bit pattern has to be associated. The switch 31 provides the additional switching contact 13.In this additional switching position IX (as in the case of the exemplified embodiment in accordance with Figure 2) the controllable power switch 1 7 is controlled by direct application of a suitable voltage U to the bridging means comprising line 22 which circumvents the decoding power control circuit 1 5. The remainder of the switch apparatus shown in Figure 3 is substantially as hereinbefore described with reference to Figure 2 and will therefore not be described further.

Switch apparatus in accordance with the invention may employ other appropriatelydesigned rotary coding switches. Thus, for example, barrel switches with an appropriate contact pattern can be used, or combinations of the various types of switch, in which the bit codes for the control of the decoding power control circuit 1 5 are generated by means of a suitable contact or cam pattern and sensing contacts or contact arrangement, whilst in the additional switching position for the direct control of the controllable power switch 1 7 by way of the direct control line 22 for example an "on"-"off" or make and break switch is used which is actuated by a suitable control cam.

Of course, it is also possible to combine each of the rotary coding switches with further switches which in a power "off" switching position switch off the total current supply or control indicator lights or like indicator.

Figure 4 shows a third exemplified embodiment of the circuit arrangement in accordance with the invention, in which Figure only part of the rotary coding switch 1 is shown and the decoding power control circuit 1 5 is not shown. Of the rotary coding switch 1, only the additional switching contact 13, actuated in the additional switching position IX, is shown as a make and break switch, which in the additional switching position connects the direct control line 22 to a voltage U. The timing output 16 of the decoding power control circuit 1 5 is indicated, which output controls the controllable power switch 1 7. The controllable power switch 1 7 consists of a bistable bipolar relay 18' having switching contacts 1 9 to connect the device 21 to a supply voltage.The bistable bipolar relay 18' is controlled by way of a relay control circuit 32 (for example in accordance with British Patent Application No. 2103042A) which generates, from the binary timing signal at the timing output 16 of the decoding power control circuit 15, upon each change of the timing signal level, suitable switc,i-over impulses for the bistable, bipolar relay 18'.

Additionally, one of the two connections of the exciting winding 20 of the relay 18' is connected a capacitor 33 of the bridging means to the direct control line 22, and the other connection is connected a resistor 34 of the bridging means to the direct control line 22. In this respect, the resistor 34 is applied to that connection of the exciting winding 20 which is, in the appropriate circumstances, earthed. If now, by adjustment of the rotary coding switch 1 into the additional switching position IX, the additional switching contact 13 is closed, then the capacitor 33 is charged up by way of the direct control line 22 and the exciting winding 20 of the relay 18'. As a result of the charging current of the capacitor 33, the bistable bipolar relay 18' is switched on.If the rotary coding switch 1 is brought out of the additional switching position IX into another switching position, then the additional switching contact 13 is opened again and the capacitor 33 is discharged by way of the exciting winding 20 of the relay 18' and the resistor 34. As a result of the discharging current of the capacitor 33, the bistable bipolar relay 18' is again switched into the "off" position. The relay control circuit 32 is thus in the additional switching position IX, in the case of this ememplified embodiment, also bridged. Alternatively, this embodiment may be modified to connect the line 22 to the relay control circuit, so that in the additional switching position IX the relay control circuit 32 receives, by way of the direct control line 22, the voltage U, in order thus to be able to switch over the relay 18'.

In this respect, then in the additional switching position IX only the decoding power control circuit 15, but not the relay/control circuit 32 is bridged.

This is for example advantageous when the relay control circuit 32 is integrated into the relay 1 8', and the connections of the exciting winding 20 are not readily accessible.

Claims

1. Switch apparatus, for controlling the power supply to electrical power consuming device, (such as a resitive heating device of an electric stove), comprising a manually-actuable rotary coding switch actuable to provide an n-bit output code; a controllable power switch; and a decoding power control circuit which is arranged to control the power switch to make available power, quantized according to the output code of the rotary coding switch, for an electrical power consuming device, characterised in that the rotary coding switch has an additional switching position, which position is provided with at least one additional switching contact connected to the controllable power switch by bridging means bridging the decoding power control circuit, to actuate the power switch in such a way that a predetermined electrical power level is provided for an electrical power consuming device.

2. Switch apparatus as claimed in Claim 1, characterised in that maximum electrical power is made available in the additional switching position of the rotary coding switch.

3. Switch apparatus as claimed in Claim 1 or 2, characterised in that the additional switching contact is electrically insulated from code contacts of the rotary coding switch, so that in the additional switching position the controllable power switch can be actuated with a voltage separately generatable from the voltage output of the decoding power control circuit.

4. Switch apparatus as claimed in any one of Claims 1 to 3, characterised in that one of the code contacts of the rotary coding switch forms part of a change-over switch which has an additional switching contact designed as a switch-over contact which is switched on in the additional switching position.

5. Switch apparatus as claimed in any one of Claims 1 to 4, characterised in that the controllable power switch consists of a relay, the bridging means comprising a direct control line which connects the exciting winding of the relay, in the additional switching position of the rotary coding switch, at least from time to time to a predetermined electrical input.

6. Switch apparatus as claimed in Claim 4, characterised in that the relay is a monostable relay, the exciting winding of which is connected in the additional switching position by way of the direct control line continuously to the predetermined voltage.

7. Switch apparatus as claimed in Claim 6 wherein the predetermined voltage is an operating voltage applied also to the decoding power control circuit.

8. Switch apparatus as claimed in Claim 4, characterised in that the relay consists of a bistable bipolar relay and a relay control circuit which controls the exciting winding of the relay; and in that an input of the relay control circuit is connected in the additional switching position by way of the direct control line continuously to the predetermined voltage.

9. Switch apparatus as claimed in Claim 4, characterised in that the relay consists of a bistable bipolar relay and a relay control circuit which controls the exciting winding of the relay; and in that the exciting winding has one connection connected by way of a capacitor with the direct control line and has another connection connected by way of a resistor to the direct control line.

10. Switch apparatus as claimed in Claim 1, wherein the rotary coding switch is substantially as hereinbefore described with reference to Figure 1 of the accompanying drawing.

11. Switch apparatus substantially as hereinbefore described with referende to Figure 2 or 3; or Figure 2 or 3 as modified by Figure 1 or 4; or Figure 2 or 3 as modified by Figures 1 and 4 of the accompanying drawings.