GB2036441A

GB2036441A - Rotary Electric Switches

Info

Publication number: GB2036441A
Application number: GB7938471A
Authority: GB
Original assignee: Diehl GmbH and Co
Current assignee: Diehl Verwaltungs Stiftung
Priority date: 1978-11-10
Filing date: 1979-11-06
Publication date: 1980-06-25
Also published as: FR2441312A1; IT7926902A0; IT1162594B; DE2848824C2; GB2036441B; DE2848824A1; FR2441312B1

Abstract

A power control arrangement for a cooking appliance has two rotary switch actuating elements 1, 1' having axially-displaceable shafts 7, 7' and provided with respective cams 10 rotatable to move a tiltable lever 11 to cause actuation of a selected one, or both, of two pairs of on-off switch contacts (17, 17') Figure 1 (not shown) respective to each of two consuming devices. The shafts 7, 7' carry contacts 9, 9' engagable with contact surfaces 4, 4' arranged in a coding pattern on a printed circuit board 4. On drawing out one of shafts 7 or 7', to lift the respective contacts, 9 or 9' and turning and releasing said shaft, a common control circuit 6 recognises a command to keep a respective relay 22 or 22' closed for a specific interval of time determined by the rotary position of the shaft 7, whereby maximum available power is supplied during said interval for start of cooking, said rotary coded position determining also the lower power. For continued cooking at the end of said interval as by varying pulse lengths of full power. <IMAGE>

Description

SPECIFICATION An Arrangement for Power Control The invention relates to an arrangement for the power control of ohmic consuming devices. There is described herein a power control arrangement more especially for an electric cooking appliance, of that kind with a control circuit for individual simultaneous power control for a plurality of consuming devices and with a respective actuating element for control of the control circuit, the power being available to the respective consuming devices in quantized form.

Power controls of the above-mentioned kind are known.

German Offenlegungsschrift No. 26 05 533 discloses electronic control means for electric cookers with digital input, the supply of the power to a consuming device being effected in pulses of different length which is dependent on the selected power level. The pulse frequency of the power pulses is constant in the continuation-ofcooking range, and in the so-called start-ofcooking range a power thrust of maximum available power is supplied to the electric consuming device, the start-of-cooking time being dependent on the selected power ievel with which, after the end of the start-of-cooking, cooking is to be continued.

Furthermore, electronic components in highlyintegrated form are known which are able to control, in the above-mentioned manner, the power of a plurality of ohmic consuming devices.

These components (for example see data sheet for General Instrument Appliance Timer Ay-5- 1250) allow for simultaneous selection of a plurality of hotplates, and connections for a startof-cooking automatic device and a function display are provided, and with them the timewise pre-setting of cooking procedues is possible.

The task of the present invention is to arrange, and couple mechanically to one another, operating elements for for example a plurality of hotplates in such a way as to make possible the control or instruction of one control circuit, common to a plurality of operating elements, in a cost-saving, service-compatible and functionallyreliable manner. Furthermore, in the case of a cooker the start-of-cooking command is desirably to be effected by way of a rotary actuating element for a respective hotplate and above all without additionally-necessary switching elements.

According to the invention, there is provided an arrangement for the power control of ohmic consuming devices, more especially for an electric cooking appliance, with one control circuit for individual simultaneous power control for a plurality of consuming devices and with a respective actuating element for control of the control circuit, the power being available to the respective consuming device in quantized form, characterised in that combined in or on a common housing or carrier are all the actuating elements and switching elements for at least two consuming devices, in that the actuating elements act by way of common mechanical control means on switching contacts by which the load circuits associated with the actuating elements can be switched on and off, and, associated with each actuating element, two sets of relatively-displaceable control contacts are provided, some of which are stationary and the others of which are in operative connection with the actuating elements, in which respect by way of these control contacts, dependent on the position of the actuating elements, a pluralitu of inputs of the control circuit are selectable simultaneously, in groups or individually.

The actuating elements for the consuming devices may be in operative connection with rotary coding switches, and there may be provided on a printed circuit board contact surfaces which co-operate electrically with movable control elements of said switches.

Furthermore, there may be provided a common control lever, responsive to movement of control cams arranged on respective shafts of the actuating elements, with said lever being operable to actuate first and second switching contacts.

The actuating elements may have associated therewith respective rotary coding switches having sliding contacts arranged so that they can be lifted off, for the switching-on of a start-ofcooking operation, from a printed circuit board which carries contact surfaces, whereby a specific bit pattern, namely 0000, is then supplied to the control circuit.

To increase the operating reliability of the arrangement, in a case where a four place coding is used, each of four code places on contact surface on a printed circuit board may be scannable at a plurality of places simultaneously.

The arrangement may have radially-arranged progressive coding contacts so arranged at a transition point that at this point a plurality of code places change simultaneously, whereby the progressiveness of the coding is interrupted.

Also, according to the invention, there is provided an arrangement for the power control of at least two ohmic consuming devices, said arrangement comprising a control circuit operable to, at will, control the consuming devices one at a time or more than one simultaneously, actuating elements, one for each consuming device, operable to control, or cause to be instructed, the control circuit, and respective switch means for causing switching of each respective consuming device on and off and controlled by the respective actuating element via mechanical movementtransmitting means common to said switch means, said actuating elements and said switch means being mounted in or carried by a common housing or carrier, each actuating element having operatively associated therewith contact means for controlling control inputs to the control circuit in dependence upon, or for causing the control circuit to be instructed in dependence upon, the position of said actuating element whereby to control via said control circuit power supply to the respective consuming device.

In the accompanying drawings, which show, by way of example, one embodiment of the invention: Figure 1 shows a section through an arrangement, constructed in accordance with the invention, in a plane perpendicular to the shafts of actuating elements, along the line I-I, Figure 2; Figure 2 shows a sectional view of the said arrangement on the line Il-Il, Figure 1; and Figure 3 shows one possibility of the arrangement of contact surfaces on a first printed circuit board of the arrangement shown in Figures 1 and 2.

Referring to the drawings, the arrangement, shown in Figure 1 and Figure 2, for power control substantially comprises a housing 2 which is common to a plurality of actuating elements 1, 1', a first printed circuit board 3 having Gray Code contact surfaces 4, 4', a second printed circuit board 5 for the reception of diagrammaticallyshown control circuit 6, a plurality of switch shafts 7, 7' each having co-formed on the one end thereof a respective actuating element 1 or 1', and having co-formed on the other end thereof a respective plate-like enlargement 8 or 8', for the reception of a respective row of control contacts, 9 or 9'. In the central region of the shafts their periphery is formed in each case as a control cam, 10 or 10', which cams come mechanically into engagement with a control lever 11 which is common to both shafts 7, 7'.Co-formed on each end of the control lever 11 is a sensing projection, 12 or 12', for contacting the periphery of the respective control cam, 10 or 10'. The control lever 11 is mounted, via a slot 13, on a post 14 co-moulded with the housing 2, the mounting of the control lever 11 on the post being such that said control lever is both bodily displaceable and tiltable in a plane perpendicular to the shafts 7, 7' of the actuating elements 1, 1'. The control lever 11 is furthermore held by a leaf spring 15, which is resiliently held between two further posts 16, 16', situated in the housing 1, and a groove 11' formed in the control lever, and the sensing projections 12, 12' which are arranged on the control lever 11 are forced against the respective control cams 10, 10' associated with them.

Associated with the two sensing projections 12, 12', are respective pairs of switch contacts 17, 17', of which one contact 1 7 of the one pair and one contact 1 7' of the other pair are carried by a common contact spring 1 7a, the counter contacts of said pairs being respectively carried one by each of two further contact springs 1 7b and 1 7c.

The latter contact springs rest on housing projections 18, 18' when the contacts are not closed. The shafts 7, 7' are axially-displaceably mounted in bores of the front wall of the housing 2 and, by means of journals 19, 19', in bores of the first printed circuit board 3. In this way the control contacts 9, 9' can be lifted off from the contact surfaces 4, 4' of the first printed circuit board 3. The control contacts 9, 9' are, in the non-raised state, forced by means of helical springs 20, 20', which are arranged between the plate-like enlargement 8, 8' of the shafts 7, 7' and the front wall of the housing 2, against the contact surfaces 4, 4' of the first printed circuit board 3.

Arranged on the reverse of the first printed circuit board 3 are a plurality of diodes 21 which are connected electrically to the control circuit 6.

Provided on the second printed circuit board 5, besides the control circuit 6 for the two load circuits whose load is controllable with the device, are respective switching relays 22, 22'.

The electrical connection to the consuming devices that are to be controlled and for the current supply is established by way of a series of flat plugs 23, which are similarly arranged on the reverse of the second printed circuit board 5. These flat plugs 23 may be connected electrically either to individual plugs or a plug board.

Co-moulded at the upper side of the housing of the switching arrangement are a plurality of spring tongues 24 which project over a plurality of respective mounting recesses 25. As a result of the arrangement of the parts 24 and 25, a plurality of switch-on control lamps 26 may be situated on the upper side of the arrangement.

Co-formed on the control cams 10, 10' are respective noses 27, 27' which are engageable with the respective sensing projections 12, 12' of the contact lever 11. By means of these two noses 27, 27' there is prevented the remaining of the spring contacts 9, 9' in a region of the contact surfaces 4, 4' in which the coding for the selection of the control circuit 6 changes in a manner to be hereinafter described.

Arranged at one end of the leaf spring 1 5 are further switch tongues 28 which co-operate electrically with counter-contacts 29 which are associated with them. As a result of this contact arrangement 28, 29, a further switching function which is associated jointly with both shafts 7, 7' can be performed.

To make clear the functioning of the embodiment shown, it will be assumed that one of the two shafts 7, 7' is rotated out of its position of rest in which the sensing projection 12 or 12' associated with the respective shaft, 7 or 7', engages in the notch of the respective control cam, 10 or 10'.

The control lever 11 slides, in this respect, at one of its sensing projections 12, 12', on the respective control cam, 10 or 10', and is, in so doing, lifted up at that side of the mechanism at which is located the actuated shaft, 7, or 7-3, said lever moving, at the slot 13, along the post 14 which is co-moulded with the housing 2. The said control lever carries out, in so doing, a rotary motion about the second of the sensing projections 12, 12', which rests in the notch of the non-actuated one of the control cams 10, 10'.

The raised sensing projection, 12 or 12', presses against the contact spring 1 7a, raises this and forces the contact on the raised end of said spring against the contact on the respective contact spring, 1 7b or 1 7c, lying opposed to it.

The upper one of the contact springs, 1 7b or 1 7c, upon the closing of the contacts, lifts off from the respective housing projection, 1 8 or 18', whereby a reliable contacting is ensured.

If both shafts 7, 7' are actuated, then both sides of the control element are raised, and accordingly both pairs of the contacts 17, 1 7' are closed. By means of the contacts 1 7 and 17', on the one hand the control circuit 6, which is common to a pluralitu of consuming devices, is energised, and on the other hand the respective load circuits are switched on or off. The control circuit 6 times the two relays 22, 22', associated with the respective consuming circuits, depending on the setting of the desired power stage at the actuating elements 1.As a result cf this movement of the control lever 11 upon rotation of one or both of the actuating elements 1, 1', the leaf spring 1 5 between the two posts 16, 1 6' comoulded on the housing 2 is so deformed that the contact springs 28 arranged at one end of the leaf spring 1 5 touch the counter-contacts 29 associated with them. The longer of the two contact springs 28, is formed to be somewhat wider than the shorter one, in order to ensure the same contact pressure at both contact points.

Associated with this contact arrangement 28, 29 is the supplying with current of means for carrying out a common sub-function of the device, for example the supplying with current of one of the function control lights 26.

The control circuit 6 controls the power supply in such a way that, after switching-on of one, or each, of each, of the consuming devices by closing, via the lever 11, the respective pair, or pairs, of the contacts 1 7, 17', the power is supplied to the or each respective consuming device in two stages, namely (a) a first supply stage in which maximum available power is supplied for a given length of time, and (b) a second supply stage in which power is supplied in pulses the length of which (and therefore the magnitude of the power supplied in this second stage) is dependent upon the rotary position of the respective shaft, 7 or 7', said pulse length being selected by turning the respective actuating element, 1 or 1', to a corresponding rotary setting.

The control contacts 9, 9' are connected securely to the respective plate-like enlargement 8, 8' of the shafts 7, 7' and, upon rotation of the shafts 7, 7' relatively to the printed circuit board 3, explore on the respective group of contact surfaces 4 or 4' opposed to them a radial progressive code, the progressiveness of which is interrupted at a transition point. If by drawing out one of the shafts 7 or 7', the respective control contacts, 9 or 9', are lifted off from the respective contact surfaces, 4 or 4', of the printed circuit board 3, against the force of the respective spring, 20 or 20', then the control circuit 6 recognises the coding-0000-and thereby the command to keep the respective one of the relays, 22 or 22', closed for a specific interval of time.This interval of time, which is the length of duration of the aforesaid first supply stage, is determined by the rotary position of the respective shaft, 7 or 7', after it has been released, and so is logically linked with the selected magnitude of the control power to be supplied in the aforesaid second supply stage. Preferably the described operation is used to heat up a hotplate, after it has been switched on, as quickly as possible to a temperature corresponding to the position of the actuating element, 1 or 1', which is associated with it.

Shown in Figure 3 is one of the possibilities of arranging on the first printed circuit board 3 the contact surface 4 which are explored by the control contacts, 9 or 9', upon rotation of the respective actuating element, 1 or 1'.

On the one hand, to increase the operational reliability of the device, errors in exploring the radial progressive code are avoided in that each of the four code places can be explored by the control contacts 9, 9' at, partially, a plurality of the circular contact surfaces 4, 4', said surfaces being in the form of segments.

Shown at 30, 30-3 on the contact surface arrangements shown in Figure 3 are the points of contact of the control contacts 9, 9' on the contact surfaces 4, 4'. In the instance shown, at the left-hand side of Figure 3 only the inputs A and C of the control circuit 6 are supplied with current, the tapping on the contact surfaces 4 being effected with two contact springs for each input.

On the other hand, the arrangement of the contact surfaces 4, 4' has been so designed that at a transition point, which is designated in Figure 3 by a respective arrow, a plurality of places of the otherwise progressive code change. Remaining of the control contacts 9, 9' on this code place, undefined for the control circuit, is prevented by the arrangement of the noses 27, 27' and their mechanical co-operation with the sensing projections 12, 12'.When the respective nose, 27 or 27', is moved against the respective projection, 12 or 12', it moves said projection upwards, and if the respective actuating element, 1 or 1', is released whilst the respective projection 1 2 or 12' is so raised by reason of its engagement with the nose, the spring pressure exerted on said nose via said projection 1 2 or 12' causes the nose, with the respective shaft, 7 or 7', to be displaced to left or right, thereby preventing the respective control contacts 9 or 9' from remaining on said undefined code place.

Shown at the right-hand side of the contact surface arrangements shown in Figure 3 are the points of contact 30' of the control contacts 9' on the contact surfaces 4', which are formed as segments of a circle, in which respect in the position shown all of the inputs A', B', C', D', of the control circuit 6 are supplied with current.

As a result of the arrangement of the contact surfaces 4, 4' on the first printed circuit board 3, there is able to be maintained, whilst avoiding an additional switch for a start-of-cooking procedure, the multilevel nature of the power regulation.

Each relay, 22 or 22', directly controls the respective load and is always operative so long as the respective load current is flowing. Each pair of switch contacts 17, 17' serves as a main switch, via which, when closed, flows the load current and the control current for the respective relay.

Claims

1. An arrangement for the power control of ohmic consuming devices, more especially for an electric cooking appliance, with one control circuit for individual simultaneous power control for a plurality of consuming devices and with a respective actuating element for control of the control circuit, the power being available to the respective consuming device in quantized form, characterised in that combined in or on a common housing or carrier are all the actuating elements and switching element for at least two consuming devices, in that the actuating element act by way of common mechanical control means on switching contacts by which the load circuits associated with the actuating element can be switched on and off, and associated with each actuating element, two sets of relativelydisplaceable control contacts are provided, some of which are stationary and the others of which are in operative connection with the actuating elements, in which respect by way of these control contacts, dependent on the position of the actuating elements, a plurality of inputs of the control circuit are selectable simultaneously, in groups or individually.

2. An arrangement for the power control of at least two ohmic consuming devices, said arrangement comprising a control circuit operable to, at will, control the consuming devices one at a time or more than one simultaneously, actuating elements, one for each consuming device, operable to control, or cause to be instructed, the control circuit, and respective switch means for causing switching of each respective consuming device on and off and controlled by the respective actuating element via mechanical movementtransmitting means common to said switch means, said actuating elements and said switch means being mounted in or carried by a common housing or carrier, each actuating element having operatively associated therewith contact means for controlling control inputs to the control circuit in dependence upon, or for causing the control circuit to be instructed in dependence upon, the position of said actuating element whereby to control via said control circuit power supply to the respective consuming device.

3. An arrangement for power control as claimed in Claim 1, characterised in that for the control or instruction of the control circuit for association with a plurality of consuming devices, there is, for each consuming device, arranged in the housing a rotary coding switch which has a rotary shaft on the one end of which is mounted the respective actuating element, and on the other end of which are mounted control contacts in the form of sliding contacts co-operable with contact surfaces which are situated opposite them on a printed circuit board, and in that arranged on each of the rotary shafts is a control cam co-operable with the common mechanical control means.

4. An arrangement for power control as claimed in Claim 3, characterised in that two actuating elements, each on a respective shaft, are provided, and in that the common mechanical control means comprise a control lever, common to both shafts, with respective sensing projections for engaging the control cams, in that arranged at the ends of the control lever are the switching contacts, said switching contacts being actuatable by movement of the sensing projections for the loading of the respective load circuit, and in that a spring is provided which forces the sensing projections against the control cams, and there being situated on this spring second switching contacts for switching on and off means for carrying out a common further function of the arrangement.

5. An arrangement for power control as claimed in Claim 3 or 4, characterised in that each of the said rotary shafts of the rotary coding switches is journalled on the one hand in the printed circuit board, and on the other hand in a front wall of the housing, in that a respective helical spring is introduced between the front wall of the housing and an enlargement which carries the sliding contacts of the respective rotary switch, said spring urging said sliding contacts against the opposed contact surfaces of the printed circuit board, in that as a result of this manner of mounting of the shafts said shafts are displaceable along their shaft axes to such an extent that the sliding contacts can be lifted off, against the force of the respective spring, from the opposed contact surfaces of the printed circuit board, in that a second printed circuit board for the reception of almost all, or substantially all, the electronic component parts is provided and in that, as a result of the arrangement of both printed circuit boards, the mechanical component parts are spatially completely separated from the electronic component parts.

6. An arrangement for power control as claimed in Claim 3, 4 or 5, characterised in that as a result of the arrangement of the contact surfaces on the, or the first, printed circuit board there is effectable a coding according to a progressive four-place binary code (Gray code) by which the inputs of the control circuit are selectable.

7. An arrangement for power control as claimed in Claim 6, characterised in that, upon rotation of one of the actuating elements and momentary lifting-off of the sliding contacts of the respective rotary switch from the contact surfaces of the printed circuit board lying directly opposite them, the control circuit receives the bit pattern 0000, whereupon the control circuit selects the consuming device, associated with the respective actuating element, for operation at maximum available power for a period of time which is dependent upon the rotary position of the said actuating element.

8. An arrangement for power control as claimed in Claim 6 or 7, characterised in that each of the four code places (A, B, C and D) is scannable by the sliding contacts at a plurality of contact surfaces simultaneously to avoid errors in sensing the progressive Gray Code.

9. An arrangement for power control as claimed in claim 6, characterised in that the contact surfaces on the, or the first, printed circuit board are so arranged radially with respect to the rotary shaft axes that upon a rotation of the sliding contacts of a respective one of the rotary switches by 3600 about the respective shaft axis a plurality of the four Gray Code places change simultaneously at a transitional point and the progressiveness of the binary code is in the respective case interrupted, and in that mounted on each of the shafts is a projection which comes into mechanical engagement with the sensing projection, associated with the respective shaft, of the control lever and prevents the sliding contacts from, at the transition point, remaining in engagement with the opposed contact surfaces.

10. An arrangement for power control, as claimed in Claim 4, characterised in that the spring is a leaf spring so mounted under bias on the control lever and on the housing of the arrangement that the sensing projections of the control lever are forced against the control cams and in that said leaf spring is so flexed upon rotation of one of the two actuating elements that by way of the second switching contacts an operation control lamp can be supplied with current, said second switching contacts being arranged at an end of the lever.

11. An arrangement for power control as claimed in Claim 5, characterised in that situated on the second printed circuit board is, for each of the load circuits, a respective switching relay for supplying current to a consuming device associated with it.

1 2. An arrangement for power control as claimed in Claim 1, characterised in that coformed in one piece with an upper side of the housing are spring tongues made from plastics material, and the end of these spring tongues project over similarly co-formed mounting recesses.

1 3. An arrangement for power control as claimed in Claim 5, characterised in that situated on the reverse of the second printed circuit board are a plurality of flat plug-in tongues which are connectable to a plug board or individual plugs.

14. An arrangement for power control as claimed in Claim 2, wherein the said arrangement is for controlling two consuming devices and the actuating elements are two in number and the said movement-transmitting means is a twoarmed lever one end of which carries a sensing projection operatively engageable with a cam rotatable by one of said actuating elements and the other end of which carries a sensing projection operatively engageable with a cam rotatable by the other of said actuating elements.-

1 5. An arrangement for power control as claimed in Claim 2 or 14, wherein the contact means for controlling control inputs to the control circuit, or for causing instruction of the control circuit, are rotary coding switches actuated by the respective actuating elements.

1 6. An arrangement for power control as claimed in Claim 15, wherein the control circuit is operable to control the power supply to the consuming devices in two stages and each of the actuating elements is a rotatable element axially movable from a normal axial position, against spring means, to cause the control circuit to be instructed, via the respective rotary coding switch, to arrange for maximum available power to be supplied, in a first supply stage, to the respective consuming device for a selected length of time determined by the rotary position of the said actuating element when released to its normal axial position, and wherein this selected rotary position of said actuating element when so released determines also the magnitude of the power to be supplied to the said respective consuming device in a second supply stage commencing at the end of said selected length of time.

1 7. An arrangement for power control of ohmic consuming devices, substantially as herein described with reference to the accompanying drawings.