ENERGY REGULATORS

Abstract: A dual output energy regulator (100) comprises first (114) and second (116) cam tracks extending substantially entirely around a rotary member (108), and a cam follower (112) for engaging in the tracks. The first cam track (114) has a "high" profile, and is associated with an "open" condition of a set of contacts (104, 106) for an auxiliary output of the regulator. The second track (116), which has a "low" profile, is associated with a "closed" condition of the contacts. The cam follower (112) moves from one track to the other as the control body (118) rotates hence switching the auxiliary load either in or out. On rotating the rotary member (118) back in the opposite direction, the cam follower (112) is prevented from re-entering the first cam track (114). In this way, substantially full range control is provided for both part load and full load applications, without requiring a separately mounted collar.

Description: Energy Regulators The present invention relates to energy regulators for controlling the supply of electrical energy to electrical loads such as cooker hot plates or grills . Typically, energy regulators comprise a micro- switch having a set of switch contacts arrangeable in the electrical supply circuit to the electrical load, a snap-acting switch contact arm operatively associated with a bimetallic actuator, and electrically energisable heating means associated with the bimetallic actuator. In such constructions, electrical power is initially supplied to the load and to the heating means which may be connected either in parallel or in series with the load. The heating means heats the bimetallic actuator, causing it to deform to the point where it causes snap- action of the contact arm to open the switch contacts and interrupt the power supply to both the load and the heating means. The bimetallic actuator then cools and deforms in the opposite direction to the point where the contact arm undergoes reverse snap-action to close the contacts once more, whereupon the cycle recommences. Thus such regulators operate on the principle of supplying power to the load over a proportion of an operating cycle, the proportion being settable by control means coupled in use to a knob or spindle. The control means normally comprises a rotary control cam member, against which a cam follower, for example provided on an ambient compensating bimetal coupled to the bimetallic actuator, abuts. It is often desirable to provide a "full load" or "part load" facility in an electrical appliance, for example a "split ring" or "split grill" in a cooker to allow a portion of a hot plate to be used for heating a small saucepan or for using a part only of the grill to grill a small amount of food. In such a case, a dual output is provided from the energy regulator. The first output is connected to a primary load which is intended to be energised whether the load is on a "full load" or "part load" setting. The second output, however, is connected to an auxiliary load which is intended to be energised in addition to the primary load only in the "full load" setting through an auxiliary set of switch contacts. The position of the auxiliary contacts is- controlled by an auxiliary cam surface engaged by an auxiliary cam follower, and when the auxiliary contacts are closed, the auxiliary load will also be energised. This can be achieved in a number of ways . In some arrangements, an auxiliary cam surface is provided on the same cam body as the main control cam surface to rotate therewith, the auxiliary cam surface being profiled such that over one half of the arc of movement of a control knob from an 'off' position, the auxiliary contacts are open, such that only the primary load is energised and over the other half of the arc, on the opposite side of the 'off' position, the auxiliary contacts are closed so that both the primary and auxiliary loads are energised. This arrangement has the disadvantage that the full range of the control must be fitted into 180° of movement of the control knob rather than 360°. In another arrangement, as disclosed in EP-A- 0,807,947, an auxiliary cam surface is provided on a collar member rotatably mounted on the control cam body. When the control knob is moved from the 'off' position to a maximum position, say 330°, from the 'off' position, the collar can rotate relative to the control cam body, so leaving the auxiliary contacts open and thus leaving the auxiliary load de-energised. Beyond that position, however, the collar moves with the main body and the auxiliary cam follower moves along the auxiliary cam surface to a position wherein the auxiliary contacts close, thereby energising the auxiliary load. As the control body is rotated in the opposite direction the collar can once again move relative to the control body and thus the auxiliary contacts remain closed. Thus if it is desired to have a 'full' load, the control knob is first twisted through a maximum angle and then turned back to the desired lower setting. In this way, a full scale control can be provided for both "full load" and "part load" settings. However, the arrangement above is difficult to manufacture. Accordingly the present invention seeks to provide a dual output energy regulator which allows a full scale control for both "full load" and "part load" settings and which is more easily manufactured. In accordance with a first aspect of the invention, therefore, there is provided a dual output energy regulator comprising means for controlling the opening and closing of a set of contacts associated with an auxiliary output of the regulator, said means comprising respective first and second cam tracks provided on a rotary member, a cam follower for engaging said cam tracks, and means for moving said cam follower from said first cam track into said second cam track during rotation of the rotary member in a first direction so as to change the condition of the set of contacts but preventing the cam follower from reentering the first cam track when the rotary member is rotated back in the opposite direction. Thus in accordance with the invention, a cam follower engages in first and second respective cam tracks. The first cam track is associated with a first condition of the set of contacts (e.g. open) and the second track with a second condition (e.g. closed) . The cam follower is able to move from one track to the other as the control body rotates so as to change the condition of the switch contacts and so either switch in or switch out an auxiliary load. This arrangement has the advantage over the above described prior art that while substantially full range control can be provided for both part load and full load applications, no separately mounted collar is needed. Preferably this switching occurs in the maximum load condition of the full or part load. In practice one of the tracks will have a "high" profile and the other a "low" profile so that say when the cam follower is engaged in the high profile track the contacts are open, and when in the low profile track they are closed. Preferably the cam tracks extend around substantially the entire rotary member. In the preferred embodiment, the tracks are separated by a wall which is apertured in a desired position to allow the cam follower to move from one track to the other. To effect the movement, the bottom of one of the cam tracks is selectively stepped or sloped into the other track so that the cam follower drops into the other track. To prevent the cam follower from reentering the first track, and to assist in guiding the cam follower towards the second track when the rotary member is rotated in the opposite direction, the step or slope is preferably angled towards the second track. Preferably, the cam follower is flexible and is preferably generally aligned with one or other of the tracks such that it will tend to move towards that track when its leaves the other track under its own resilience . After the rotary member has rotated fully in the other direction, the cam follower should be returned to the first track for the next operation. In order to move the cam follower from the second track back into the first track, it is preferably sloped at its other end to the same level as the first track. This preferably occurs at the "off" position of the rotary member. To assist in guiding the cam follower into the first track, the wall separating the tracks may be angled towards the second track so that as the rotary member is rotated in the first direction once again the wall captures the cam follower and leads it into the first track. Further means may be provided if required to guide the cam follower from one track to the other at the appropriate time. Preferably the cam surfaces are provided on the main control body i.e. that which carries the main control cam. The cam surfaces may be provided on any convenient surface of the control body, for example a radially facing edge thereof, but in a preferred embodiment , they are provided on a face thereof . The invention has been described above as being applied in a dual output energy regulator wherein the auxiliary load is switched in or out only after the rotary member has been rotated to the maximum power setting in one direction. However, the invention has broader application. For example an arrangement could also be envisaged wherein the cam follower selectively enters one or other of the tracks from an "off" position of the rotary member depending on the direction of rotation from that off position. From a further broad aspect, therefore, the invention provides a dual output energy regulator comprising means for controlling the opening and closing of a set of contacts which are associated with an auxiliary output of the regulator said means comprising respective first and second cam tracks extending around a rotary member, and a cam follower which is operatively coupled to the contacts and which is selectively engageable in one or other of said tracks so as to determine the condition of said contacts in dependence upon the direction of rotation of said rotary member from an initial position. With this arrangement, therefore, one or two loads may be energised depending on the direction of initial rotation and at any angular position the number of loads energised will depend on the initial direction of rotation. From a further broad aspect, therefore, the invention provides a dual output energy regulator comprising means for controlling the opening and closing of a set of contacts which are associated with an auxiliary output of the regulator said means comprising respective first and second cam tracks extending around a rotary member, and a cam follower which is operatively coupled to the contacts and which is selectively engageable in one or other of said tracks so as to determine the condition of said contacts in dependence not only upon the rotational position of the rotary member but also on a direction of rotation thereof. Preferably the respective tracks extend substantially completely around the rotary member, whereby, as in the earlier embodiment, a fuller range of control setting is available for each load. The arrangement described above may also incorporate features of the earlier embodiment whereby the cam follower can move from the first track into the second track after a predetermined angular rotation of the control member. The various arrangements described above could also be used in conjunction with a further, separate, switching mechanism selectively to power three loads. In particular, the further switching mechanism may switch in and out a third load in a "conventional" manner, i.e. over approximately 180° movement from an "off" position the third load is disconnected and from 180°-360° it is connected. Such an arrangement is used to switch in a second load in the Applicant's commercially available OG 2004 regulator, where the appropriate cam track is provided on the underside of the main control body. With such a switching mechanism superimposed on that in accordance with the invention, the following operating regimes could be envisaged: Movement from "off Loads energised 0-180° clockwise: first load only 180°-360° clockwise: first and third loads 0-180° anti-clockwise: all three loads 180°-360° anti-clockwise first and second loads Typically the first load would be the main load and the second and third smaller loads. Some preferred embodiments of the invention will now be described by way of example only with reference to the following drawings in which: Fig. 1 is a perspective view of a dual output energy regulator; Fig. 2 is a plan view of a dual output energy regulator in accordance with the invention, with certain parts removed for clarity; Fig. 3 is a partial section along line A-A of Fig. 2; Fig. 4 is a perspective view of the control member of Figs . 2 and 3 ; Figs. 5A to 5E shows schematically the engagement of certain components of the energy regulator of Figures 2 to 4 in different operational positions; Figs . 6A & 6B are developments of the cam profiles of the rotary member of the energy regulator of collar of Figs. 2 to 5 ; Fig.7 shows a modification of the regulator of Figs 1 to 6; Fig. 8 shows a further modification of the regulator of Figs. 1 to 6 Fig. 9 shows a circuit diagram for a further embodiment of the invention using the arrangement described in Fig. 8; and Figs 10A to 10C show the operating conditions of the various loads shown in Fig 9. With reference firstly to Fig. 1, an energy regulator 2 (shown with its lid removed) comprises a snap-acting microswitch 4 having a contact arm 6 pivotally mounted on the free end of a bimetallic actuator 10. A snap acting "C" spring 12 is released from the contact arm 6 and engages in a fulcrum provided in an output tab 14. A movable contact 16 is mounted on the free end of the contact arm 6, and a fixed contact 18 is provided on the upper face of an input tab 20. An electrical circuit to a primary load such as a first section of a grill element, not shown, is established through the input tab 20, the contacts 16,18, the spring 12, and the output tab 14. A ceramic substrate heater 22 is mounted on the root end of the bimetallic actuator 10, and when energised, causes the actuator 10 to deflect, to open the contacts 16,18 with a snap-action after a predetermined deflection. The electrical supply to the heater 22 is made via the input tab 20, the contacts 16, 18, the contact arm 6, the bimetallic actuator 10, a tongue 24 released therefrom, and a resilient connection 26 connected to a tab 28. Thus when the contacts 16,18 open the load and the heater are de-energised, allowing the actuator 10 to cool and deflect in the other direction, to close the contact once again. The actuator 10 forms one arm of a bimetallic member 30, the other arm 32 of which acts as an ambient temperature compensator in a manner well known in the art. It is provided with a cam follower 34 which engages in a cam track 36 formed in a control member 38. The control body 38 is of plastics and attached to, or formed with, a spindle 40, to the top end of which may be attached a knob, not shown. As the spindle 40 is rotated, the cam track 36 is rotated, with the follower 34 moving up and down accordingly. As it does so, the free end 8 of the actuator 10 is also moved up or down, so changing the amount of deflection necessary to open or close the switch contacts 16,18. Thus the operating point of the regulator is set by the angular position of the spindle. The output tab 14 is also provided with a fixed contact 42. A movable contact 44 is mounted on the free end of a resilient conductive member 46 which is provided with an output tab 48 which in use is connected to a load such as a second section of a grill pan element. The conductive member 46 is provided with a cam follower 50 which engages a cam surface 52 provided radially inwardly of the cam track 36. Depending on the auxiliary cam profile, the contacts 42,44 will be either open or closed. When open, no current will flow to the auxiliary load, but when closed, a current will flow from the tab 14 via the contacts 42,44, the member 46 and output tab 48. However, a current will only flow when the microswitch contacts 16,18 are closed. Thus when the contacts 42,44 are closed, both the primary and auxiliary loads are controlled by the opening and closing of the contacts 16,18, and in dependence on the position of the spindle 40. With reference to Figs. 2 to 6, there is shown a generally similar dual output energy regulator, but in accordance with the invention, with certain parts removed for clarity. In particular the primary control components have been removed, (including the main control cam surface) leaving essentially only those components associated with switching the auxiliary load. Referring to Figs. 2 to 4 , the regulator 100 comprises a primary output tab 102 which mounts a fixed contact 104. A movable contact 106 is mounted on the free end of a resilient electrically conductive member 108 which has an auxiliary output tab 110 at its other end. A cam follower 112 is formed on the member 108 and is biased downwardly into selective engagement with a first cam track 114 or a second cam track 116. The cam follower 112 is positioned such that it is generally aligned with the second track 116. The cam tracks 114, 116 are formed on the main rotary control member 118 of the energy regulator and are positioned radially inwardly of the main control track (not shown for purposes of clarity) which controls the operating point of the regulator as described above . The cam tracks 114, 116 are generally circular and extend around the complete periphery of the control member 118. The first track 114 is arranged radially inwardly of the second track 116 and is separated therefrom by a wall 120. The radially outer surface of the first track 114 and the radially inner surface of the second track 116 is defined by the wall 120. A gap 130 is formed in the wall 120 so as to allow the cam follower 112 to move between the tracks 114, 116. The wall 120 is formed on a constant radius from one end 132 for approximately 215° to a point 134, whereupon it assumes an elliptical profile 136 to its other end 135. This effectively moves the wall 120 closer to the second track 116 for a reason which will be described further below. As can be seen from Figure 6 A and 6B the first track 114 has a higher profile 122 than the profile 124 of the second track 116, relative to a datum surface 126. The effect of this is that when the cam follower 112 is engaged in the first track 112 it will be in a raised position, thereby causing the contacts 104,106 to be open, thereby disconnecting the auxiliary load. However when the cam follower is engaged in track 114, it is in a lower position in which the contacts 104, 106 are closed, so that the auxiliary load is connected. The first track has a constant profile 138 over substantially its entire length (about 340°) , except for a step 140 at one end 142. The step 140 drops the profile 122 to the level of that second track 116. As can be seen from Fig. 2, the step 140 is angled inwardly from the end 142 of the first track, for reasons that will be explained further below. The second track 116 also has a substantially constant profile over about 315° of its extent and a ramp 146 at one end 148 which brings the track 116 up to the level of the first track 114. The rear face 147 of the ramp 146 is vertical. Operation of this switching mechanism will now be described. In the condition shown in Fig. 2 and 5A, the regulator is in an "off" condition with the main contacts of the microswitch and the contacts 104,106 open. In this position a dog 150 formed to extend from the control member 118 engages with one side of a dog 152 provided on the main regulator housing, so that the control member 118 can only be rotated clockwise. As the control member is rotated clockwise, the cam follower 112 engages the end 135 of the wall 120 which channels it into the first track 114. The cam follower 112 can accommodate this deflection due to its inherent resilience . The clockwise movement of the control member 118 continues for about 308° until it reaches the position shown in Fig. 5B. This movement does not deflect the cam follower 112 since it will be recalled the cam profile 138 over this region is flat. At this position, the cam follower is just at the edge of the step 140 in the profile 122 of the first track 114. This position corresponds to the maximum power setting for the load controlled by the regulator. Further rotation of the control causes the cam follower 112 to drop into the step 140 under its own resilience, as shown in Fig. 5C. As it does so, the contact 106 moves into contact with the fixed contact 104 thereby connecting the auxiliary load. Further rotation of the control member 118 in the clockwise direction is prevented by the dog 150 coming into contact with the dog 152 on the regulator housing, and also because of engagement of the cam follower 112 with the rear face 147 of the ramp 146 of the second track 116. Accordingly, the control member 118 must now be rotated ant-clockwise. Although the cam follower is generally aligned with the second track 116, it may not move fully over to that position due to friction. However, as the control member 118 is rotated, the cam follower will be deflected towards the second track 116 by virtue of the radial angling of the step 140 and the chamfered end 132 of the wall 120. Further anti-clockwise movement of the control member 118 reduces the setting of the combined load through the main control cam (not shown) . The contacts 104,106 remain closed since the track profile 144 is level until it reaches the foot of the ramp 146 on the second track 116, as shown in Fig. 5E. Further rotation of the control member 118 to the "off" position of Fig 5A then causes the cam follower 112 to travel up the ramp 146, so opening the contacts 104,106 and disconnecting the auxiliary load. The operation cycle can then repeated as required. In this simple manner switching in and out of an auxiliary load can be achieved without the need for separately mounted cam parts. It will be understood that modifications can be made to the above described embodiment within the scope of the invention. In one such a modification, the first track 114 may be provided with means which assist in moving the cam follower 112 towards the second track 116. Such means may comprise a projection 160 from one wall of the first track 114 which is angled toward the second track 116. Such a projection 160 is shown in phantom in Figure 5D. In another modification, the second track 116 may be provided with means which act to move the cam follower 112 toward the first track 114 after the control member 118 has been rotated to its "off" position. In particular, a projection 162 may extend from the side wall of the second track 116 which is angled to urge the cam follower 112 towards the first track 114. Such a projection is shown in phantom in Fig. 5E. Alternatively, or additionally, the floor of the ramp 146 of the second track 116 may be angled towards the first track 114 so that the cam follower 112 slides down the slope to wards the first track. A sloped portion 164 is shown in phantom on Fig. 5E . The embodiment described could be modified to operate in a different manner. For example, by removal of the dog 150 on the control member 118 and any necessary modification of the tracks 114 and 116, the cam follower 112 could be arranged to enter either the first track 114 or the second track, depending on the direction of rotation of the control member 118 from its "off" position. One such an arrangement is shown in Fig. 7. In Fig 7, the dog 150 has been removed from the control member 118 and the ramp 146 modified such that its rear face 147' is sloped rather than vertical. This allows the cam follower to drop into the outer track 116 when the control body is rotated anti-clockwise to a position at which both loads typically will be fully energised. The sloped face 147' allows the cam follower to rise up the ramp 146 when the control member is rotated in a clockwise direction. The arrangement shown also allows the cam follower 112 to drop into the outer track 116 after rotation of the control member 118 in a clockwise direction, as in the earlier embodiment. A further modification of the arrangement of Figs. 1 to 6 is shown in Figure 8. In this embodiment, the top surface 154 of the ramp 146 is extended towards the end of the first track 114 and the wall 120 extended circumferentially and angled so as to guide the cam follower 112 from the surface 154 into the outer track 116 when the control member 118 is rotated anticlockwise. The rear face 147'' of the ramp 146 is again sloped so as to allow the cam follower 112 to climb the ramp 146 when the control member 118 is rotated in a clockwise direction. The arrangement of could also be combined with a further switching mechanism in which a third load is selectively switched in and out. Such an operating regime is illustrated in Figs. 9 and Figs. 10A to IOC. With reference to Fig. 9, three loads L lf L 2 and L 3 are controlled. Loads L 3 is controlled by a cam arrangement in accordance with the invention, in particular that arrangement shown in Fig. 8 so that when the rotary member is rotated clockwise it is switched on and when the rotary member is rotated anti -clockwise it is turned off (see Fig. IOC) . Load L 2 is controlled by a separate switching mechanism controlled by a separate cam track, in particular arranged on the undersurface of the control body 118. Such a switching arrangement is used in Applicant's commercially available OG 2004 regulator where it is used to switch in and out a second load When the control body 118 is rotated clockwise L 2 is off for 180° and on for 180° (see Fig. 10B) L 2 is energised at all times, with its power setting ( and indeed the power setting of all switched in loads) determined by the main control cam profile. In this embodiment, as shown in Fig. 10A, the power setting rises from a minimum at about 30° to a maximum at about 154° and drops from a maximum at 216° to a minimum at 330°. From Figs. 10A-10C it will be seen that the condition of Load L 3 will depend on the direction of rotation of the control member 118 from the off position. Thus in typical positions A and B as shown in the Figs., the following occurs A B λ on (clockwise or anti-clockwise) L on L 2 off (clockwise or anti-clockwise L 2 on L 3 off if turned anticlockwise L 3 off antion if turned clockwise clockwise on clockwise From this it will be seen that depending on which way the control body is rotated from "off" and on the particular angular position, various combinations of loads can be energised. It will be appreciated that the embodiments described earlier may also be usable with further switching mechanisms.

Claims: Claims 1. A dual output energy regulator comprising means for controlling the opening and closing of a set of contacts associated with an auxiliary output of the regulator, said means comprising respective first and second cam tracks provided on a rotary member, a cam follower for engaging said cam tracks, and means for moving said cam follower from said first cam track into said second cam track during rotation of the rotary member in a first direction so as to change the condition of the set of contacts but preventing the cam follower from reentering the first cam track when the rotary member is rotated back in the opposite direction. 2. An energy regulator as claimed in claim 1 wherein said cam tracks extend around substantially the entire rotary member. 3. An energy regulator as claimed in claim 1 or 2 wherein the tracks are separated by a wall which is apertured in a desired position to allow the cam follower to move from one track to the other. 4. An energy regulator as claimed in claim 3 wherein the bottom of one of the cam tracks is selectively stepped or sloped into the other track so that the cam follower can drop into the other track. 5. An energy regulator as claimed in claim 4 wherein the step or slope is angled towards the other track. 6. An energy regulator as claimed in claim 3 , 4 or 5 wherein the wall separating the tracks is angled towards the second track so that as the rotary member is rotated in the first direction the wall captures the cam follower and leads it into the first track. 7. An energy regulator as claimed in any preceding claim wherein the cam follower is flexible. 8. An energy regulator as claimed in any preceding claim wherein the cam tracks are provided on the main control body. 9. An energy regulator as claimed in claim 8 wherein the tracks are provided on a face of the control body. 10. A dual output energy regulator comprising means for controlling the opening and closing of a set of contacts which are associated with an auxiliary output of the regulator said means comprising respective first and second cam tracks extending around a rotary member, and a cam follower which is operatively coupled to the contacts and which is selectively engageable in one or other of said tracks so as to determine the condition of said contacts in dependence upon the direction of rotation of said rotary member from an initial position. 11. An energy regulator as claimed in claim 10 wherein the respective tracks extend substantially completely around the rotary member. 12. A dual output energy regulator comprising means for controlling the opening and closing of a set of contacts which are associated with an auxiliary output of the regulator said means comprising respective first and second cam tracks extending around a rotary member, and a cam follower which is operatively coupled to the contacts and which is selectively engageable in one or other of said tracks so as to determine the condition of said contacts in dependence not only upon the rotational position of the rotary member but also on a direction of rotation thereof. 13. An energy regulator as claimed in any preceding claim comprising a further switching mechanism selectively for switching in and out a further output.

Inventors: PRICE IAN GARY, PRICE, IAN, GARY
Applicants: PRICE IAN GARY, STRIX LTD, PRICE, IAN, GARY, STRIX LIMITED
Application year: 2000
Main classification: H01H37
IPC codes: H01H19, H01H89