AU2021215304A1 - Heating system control - Google Patents

Abstract

t- II/-R-URU ABSTRACT A mechanical control system 1 for a heating system. The heating system having an exterior E and an input member IS turnable, relative to the exterior, to vary a temperature of the heating system and to deactivate the heating system. The 5 mechanical control system comprises a deactivation spring portion 3a (for turning the input member), a first turning portion 5 (user-turnable to load the deactivation spring portion) and a mechanical timer to restrain the deactivation spring portion for a timer period then release the deactivation spring portion to turn the input member to deactivate the heating system. 218 CY) IC)) LO CO IC)O N~t FCD FC ICO cc co

Description

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HEATING SYSTEM CONTROL FIELD

The invention relates to heating systems and control systems therefor.

BACKGROUND

Operating some heating systems such as a burner system of a gas stove entails a risk that the operator will forget to deactivate the system leading to waste and danger, e.g. if a pot of soup is forgotten on a gas stove the stove may burn for an extended period (thereby wasting gas) and the pot may boil dry and then catch fire.

In principle, an operator might mitigate this risk by using a simple battery powered timer manually settable to alarm after a timer period. The operator may set the timer each time the heating system is activated. The inventors have recognised that, in practice, such a timer would be all too easily forgotten or disregarded 'just this once'; an alarm is of no assistance if the operator has left leaving no one in the vicinity of the timer to hear the alarm; and there is the risk of the timer failing.

Accordingly the invention aims to provide improvements in and for heating systems, or at least to provide a useful alternative for those concerned with heating systems.

It is not admitted that any of the information in this patent specification is common general knowledge, or that the person skilled in the art could be reasonably expected to ascertain or understand it, regard it as relevant or combine it in any way before the priority date.

SUMMARY

One aspect of the invention provides a mechanical control system for a heating system; tI-IZIRURU

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the heating system having an exterior and an input member turnable, relative to the exterior, to vary a temperature of the heating system and to deactivate the heating system;

the mechanical control system comprising

a deactivation spring portion for turning the input member;

a first turning portion user-turnable to load the deactivation spring portion;

a mechanical timer to restrain the deactivation spring portion for a timer period then release the deactivation spring portion to turn the input member to deactivate the heating system.

The mechanical control system may have a winding configuration (in which the first turning portion is user-turnable to load the deactivation spring portion) and a temperature-adjusting configuration in which the first turning portion is turnable, to turn the input member to adjust the temperature. Preferably the first turning portion is axially movable from a winding position (in which the first turning portion is user turnable to load the deactivation spring portion) to a temperature-adjusting position in which the first turning portion is turnable, to turn the input member to adjust the temperature. The first turning portion may be axially movable to an ignition position to depress the input member to ignite the heating system.

The system may comprise a second turning portion user-turnable to adjust the timer period.

Preferably there is a timer spring portion for powering the timer mechanism. The first turning portion is preferably user-turnable to load the timer spring portion.

The mechanical control system may predominantly consist of a unit retrofittable to the heating system. Preferably the mechanical control system comprises one or more adhesive portions by which the unit is attachable to the exterior of the heating apparatus.

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The mechanical control system may comprise a restraint for restraining the first turning portion against turning when the heating system is deactivated. Preferably the first turning portion is axially movable to disengage the restraint.

The input member may be a stub shaft. Preferably the mechanical control system comprises a socket to fit over the stub shaft.

The heating system may be a portion of a gas cooking appliance.

Another aspect of the invention comprises a mechanical control system and the heating system.

BRIEF DESCRIPTION OF DRAWINGS

An embodiment of the apparatus will now be described by way of example only with reference to the accompanying drawings in which:

Figure 1 is a perspective view of a control system in situ;

Figure 2 is a sequence of elevation views showing an input shaft and the control system at different axial positions;

Figures 3 to 20 illustrate an input shaft and the control system with the knobs omitted to reveal the inner workings of the control system;

Figure 3 is a sequence of elevation views corresponding to the sequence of Figure 2;

Figures 4a, 4b and 4c are elevation views;

Figures 5 to 13 are section views corresponding to section lines in Figures 4 a to 4c:

Figure 5 corresponds to the line B-B;

Figure 6 corresponds to the line K-K;

Figure 7 corresponds to the line C-C; t1IA-I/RIU

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Figure 8 corresponds to the line D-D;

Figure 9 corresponds to the line F-F;

Figure 10 corresponds to the line G-G;

Figure 11 corresponds to the line H-H;

Figure 12 corresponds to the line I-I;

Figure 13 corresponds to the line J-J;

Figure 14 is a plan view;

Figures 15 to 18 are section views corresponding to the section lines in Figure 14:

Figure 15 corresponds to the line M-M;

Figure 16 corresponds to the line P-P;

Figure 17 corresponds to the line Q-Q;

Figure 18 corresponds to the line R-R; and

Figures 19 and 20 are perspective views.

DESCRIPTION OF EMBODIMENTS

Various examples are described below. The invention is not limited to these examples. Rather, the invention is defined by the claims.

In a typical gas stove there are heating systems each having a respective burner and a respective input shaft IS projecting outwardly through a respective hole in a sheet metal exterior of the stove. The input shafts are fitted with knobs by which the input shafts are turnable. Turning a knob counterclockwise (CCW) away from a deactivation position causes gas to flow from the corresponding burner. Depressing tI-IZIRURU

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the knob activates an igniter to ignite the gas. The knob can be turned to regulate the gas flow and thereby control the temperature of burner. Turning the knob clockwise (CW) to the deactivation position shuts off the gas and thereby deactivates the burner.

Some gas stoves have two depression stages as described above. '3-stage' stoves each comprise an interlock that prevents the knob from being turned to initiate gas flow until the knob has been pressed away from its free condition. After the knob has been turned it is further depressed to ignite the gas. Typically once the knob is released it pops up to the intermediate, gas adjusting, stage then pops up to its initial position when the knob is turned to shut off the gas.

A control system suited to such a gas stove is described herein by way of example only. Other examples of the control system may be usefully employed in other contexts, e.g. in the context of an oven having an input shaft that can be turned to set a thermostat and that cannot be depressed to ignite a burner.

Figure 1 is a perspective view of a control system 1 and a portion of a sheet metal exterior E of a stove to which the control system is fitted. The system comprises a deactivation spring portion 3 (Figure 8), a first turning portion in the form of a temperature knob 5 and a mechanical timer 7 (Figure 10). The control system 1 further comprises a second turning portion (in the form of a timer knob 9), a mounting plate 11 and an adhesive pad 13.

The turning portions could take other forms, e.g. the knob 5 might be replaced by a wheel or a handle having a graspable radial extent.

The control system 1 is configured to fit over an end of the input shaft IS (Figure 17) in a manner akin to a conventional stove knob. The adhesive pad 13 serves to adhere the system 1 to the exterior E whereby the control system is easily retrofittable. Preferably the adhesive pad is formed by applying double-backed adhesive to an underside of the mounting plate 11. Optionally, the pad might be first applied to the exterior E; indeed, other forms of adhesive and other modes of tI-IZIRURU

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attachment more generally are possible. Indeed, a non-retrofittable variant of the control system 1 might be integrated with a stove.

The control system 1 comprises an inner mechanism 15 housed within a housing 17. In this case the housing comprises the knobs 5, 9 and the mounting plate 11. The housing 17 shields the inner mechanism 15 from dust and debris such as cooking fats.

The knobs 5, 9 are mounted to turn with respect to the exterior E. In this example they are mounted to turn about the axis of the input shaft IS. In this case each knob has a round exterior concentric to that axis. The timer knob 9 takes the form of a short upright circular wall. The mounting plate 11 defines a circular channel 11a that accommodates a bottom of the timer knob 9. The temperature knob 5 takes the form of a downwardly open cup that fits over the inner mechanism 15. In this case a circular bottom of the knob 5 sits inside the timer knob 9 with clearance to facilitate the axial movement of the knob 5 illustrated in Figure 2.

The knob 5 is depressible from position A to a winding position B and onwards to an ignition position C. Position A may be a lock out position depending on the angular orientation of the knob 5. In the context of a 2-stage input shaft it is also a temperature adjusting position. Figures 4a to 19 illustrate various components of the control system 1 in system's winding configuration corresponding to position B. Figure 20 shows the system's deactivated configuration corresponding to position A.

Turning to Figures 3 and 19, the inner mechanism comprises a base layer 19, a mid layer 21 and a top layer 23. A temperature member 25 is centrally mounted within the top layer 23. The temperature member 25 is mounted on central shaft 27 and is free to move both axially and rotationally relative to that shaft.

The temperature member 25 comprises a horizontal gear portion 25a and, above that gear portion, engagement features 25b by which the temperature member 25 is fixed to the temperature knob 5 to move therewith. In this case the engagement features take the form of four upwardly directed drive lugs dimensioned to firmly engage corresponding recesses in a ceiling of the temperature knob 5. There are other ways tI-IZIRURU

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in which the gear portion 25a might be mounted to move with the temperature knob 5.

The inner mechanism 15 comprises a horizontal middle plate 29 and a horizontal top plate 31 fixed with respect to each other. The plates 29, 31 define the chassis of a floating unit 33 carry the gears of the inner mechanism 17 and mounted to axially float with respect to the mounting plate 11.

The mounting plate 11 carries three posts 35 by which the floating unit 33 is mounted. Each post 35 has a section bracketed by stops (opposed top and bottom shoulders in this case) and upon which the middle plate is capture. There are other ways in which the unit 33 may be mounted to float. Each post 35 has a compression spring acting between its lower shoulder and an underside of the middle plate to upwardly bias the floating unit 33. There are other ways in which one or more springs might be mounted to upwardly bias the floating unit.

As the temperature knob 5 is pressed from position A to the winding position B, the temperature member 25 slides axially down along the shaft 27. As the temperature knob 5 is pressed further down, the floating unit 33 is downwardly driven until the temperature knob reaches position C.

As best shown in Figures 17 and 19, the control system 1 comprises a drive member 37 made up of drive socket 37a extending downwardly from a horizontal gear portion 37b. The drive member 37, temperature member 25 and shaft 27 are concentric to each other. The drive member 37 extends downwards through a central hole in the mounting plate 11 and is downwardly open to fit over the input shaft IS. The drive socket is shaped to engage and turn the input shaft. In this case the drive socket and the input shaft have complementary D-shaped profiles.

The knob 5 and drive member 37 are mutually connected to turn in unison. Whilst in principle the knob 5 and drive member 37 might turn in unison in opposite directions and/or at differing rates, preferably they are connected to turn in the same direction and at the same rate to provide users with a feel that is familiar from conventional stove knobs.

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In this example knob 5 and drive member 37 are mutually connected via permanently engaged transmission 39 (Figure 16) to turn in unison as if they are directly connected albeit that there is no direct connection in this case.

In this case the transmission 39 is a composite shaft comprising gear members 39a, 39b mounted on and mutually connected by shaft member 39c. The plates 29, 31 are captured on the shaft member 39c between the gear members 39a, 39b whereby the transmission moves axially as part of the floating unit 33. The transmission 39 transfers drive from the top layer 23 to the base layer 19. The gear member 39a meshes with gear portion 25a whilst the gear member 39b meshes with the gear portion 37b. The gear members 39a, 39b have the same number of teeth as each other and the gear portions 25a, 37b have the same number of teeth as each other.

A transmission 41 is engageable to connect the knob 5 to knob 9 (Figures 1, 16 and 20) and to the mechanical timer 7. In this case the connection is via gear train 43 and internal ring gear 45. Other forms of transmission are possible. Indeed a still advantageous variant of system 1 may do without the transmission 41 and comprise a deactivation mechanism that is wound and set independently of the knob 5.

This example of the transmission 41 comprises a gear 41a within the base layer 19 and mounted on shaft 41b. The shaft 41b is axially movable and upwardly biased in this case by a compression spring 41b' embracing a portion of the shaft (Figure 16). The top of the shaft 41b extends upwardly into the top layer and is positioned to engage, and be driven down, by the ceiling of the knob 5. There are other ways by which the knob 5 might be upwardly biased.

As the knob is pressed from position A to winding position B, the gear shaft 41b is driven to move the gear 41a downwardly into engagement with gear member 39b and gear 43a of gear train 43 (Figures 12 and 13).

The gear train 43 includes a sequence of three gear pairs 43b, 43c, 43d each comprising a smaller gear and a larger gear fixed with respect to the smaller gear. The gear 43a meshes with the smaller gear of the gear pair 43b. Each larger gear of the gear pairs 43b, 43c meshes with a downstream smaller gear. The larger gear of tI-IZIRURU

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the gear pair 43d meshes with teeth on the inside of an internal gear 45. In this case, each of gear 43a and gear pairs 43b, 43c, 43d is carried by a respective shaft extending upwardly from the mounting plate 11 and is mounted to slide downwardly therealong against a compression spring, whereby components 43a to 43d move as part of the floating unit 33.

The internal gear 45 circumscribes the inner mechanism 15 and is fixed with respect to the timer knob 9. A set, in this case two, idler gears 45a and gear pair 43d align the internal gear 45 (see Figure 13).

In this case the transmission 41 is engageable to connect the knob 5 to knob 9 and define a multiplication ratio whereby the knob 9 turns faster than the knob 5. In this case the multiplication ratio is about 4 and the knobs 5, 9 turn in the same direction whereby the knob 5 can be pressed from position A to position B and turned1 turn CCW to turn the knob 9 about one full turn CCW. As will be described the position of the knob 9 corresponds to a remaining timer period.

This example of the timer 7 comprises an escapement 7a, a gear train 7b and the knob 9 (Figure 10). The timer knob 9 is connected to the escapement 7a via the gear train 7b and a transmission 47 (Figures 1 and 20). The transmission 47 comprises gear 47a residing in the top layer 23 and fixed with respect to the gear pair 43b by shaft 47b. The gear 47a meshes with gear 47c in the top layer 23. The gear 47c is fixed to rotate with shaft 47d by which shaft power is transferred from the top layer down to the gear train 7b in the middle layer. A slippable-connection connects the first gear 7bi of the gear train 7b to the shaft 47d.

Turning to Figure 8, spring 3 resides in a downwardly open pocket on an underside of the middle plate 29. The spring 3 comprises a ribbon of spring steel. One end of the ribbon is coiled about and engaged with the shaft 27 to define a deactivation spring portion. The other end of the ribbon is coiled about and engaged with the shaft 47d to define a timer spring portion 3b. There are other options. Any convenient spring might be adopted. The deactivation spring portion might take the form of a dedicated deactivation spring. When the temperature knob 5 is depressed to position B and turned (about 1/ turn CCW in this case) the shaft 47d is turned to load the tI-IZIRURU

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timer spring portion 3b. The slippable-connection between gear 7bi and shaft 47d slips to allow the shaft 47d to move whilst the gear 7b remains essentially locked by the escapement 7a.

Turning to Figure 11, the middle layer 21 comprises pawl member 51 and ring 53 surrounding the pawl member 51. The pawl member is fixed to rotate with the shaft 27 and defines a trio of pawls co-operable with rachet teeth about an interior of the ring 53. The ring 53 comprises external gear teeth engaged by gear 55. When the timer 7 is counting down, the gear 55 is held stationary and in turn the ring 53 is held stationary. The ratchet teeth of ring 53 are co-operable with the pawl member 51 to allow the shaft 27 to turn only CCW with respect to the ring 53.

As best shown in Figures 13 and 17, a disk 57 sits under the middle plate 29. The disk is fixed to the shaft 27 and carries an eccentrically mounted downwardly projecting pin 57c. A free end of the pin 57c sits within a groove 37c of the drive member 37. The groove 37c is upwardly open and runs about an incomplete circle concentric to the axis of the input shaft IS.

During the winding operation, when the knob 5 is pressed to position B and turned1 turn CCW, the drive member 37 is driven via the transmission 39 to turn therewith. The disk 57, shaft 27 and pawl member 51 turn CCW in unison with the drive member 37 whilst the gear 55 and in turn the ring 53 are held stationary. This action loads the deactivation spring portion 3a (Figure 8).

The mechanism by which the gear 55 (Figure 11) is held stationary whilst the timer runs out will now be described. A ratchet wheel 59 sits above and is fixed with respect to gear 55. An arm 61 sits alongside the ratchet wheel 59. The arm extends horizontally and is mounted to pivot about upright axis 61a. On one side of the axis 61a, the arm has pawl 61b co-operable with the ratchet wheel 59. On the other side of the axis 61a, the arm 61 has a pin 61c projecting upwardly through a window 31a in the top plate 31 (Figure 9).

A timing cam 63 and a gear 65 are fixed with respect to each other and are mounted on the shaft 27 (Figure 7 and 9). The cam 63 and gear 65 are mounted to turn relatively about the shaft 27 within a limited range of relative motion.

The gear 65 meshes with gear 47c whereby the cam 63 turns as the timer is wound and as the timer counts down. On the one hand, the slippable-connection between the gear 7bi and the shaft 47d is configured to drive the shaft 47d (and in turn gears 47c, 65 etc) as the timer counts down. On the other hand it is configured to slip to allow the timer to be wound or for the timer knob 9 to be turned to adjust the timing period essentially independently of the escapement 7a. The slippable-connection might take the form of a simple friction fit although more elaborate arrangements, e.g. spring loaded torque-limiting arrangements, are possible.

In this example, the gear 7bi is a plastic gear member and the shaft 47d is metallic, and the slippable connection comprises top and bottom friction members between which the plastic gear is clamped. The friction members are fixed with respect to the shaft. Each friction member is a thin metallic construction having a slightly dished shape. The top friction member is predominantly conical, its walls extending outwardly at a shallow angle from horizontal towards an upturned outer periphery defining a generally toroidal contact surface that is presented to the top of the gear 7bi. The lower friction member is essentially the inversion of the top friction member and presents a generally toroidal surface to the underside of the plastic gear. This arrangement advantageously allows for a controlled degree of friction that remains relatively constant over time even as the friction surfaces of the plastic gear wears.

As the timer counts down, the escapement mechanism applies a very small torque to rotate the shaft 47d. When the timing mechanism is wound, torque applied to the shaft 47d causes the escapement mechanism to lock and as the torque rises beyond a threshold the slippable connection slips to enable the shaft 47d to turn independently of the gear 7bi.

The cam 63 comprises a cutout 63a interrupting an otherwise round exterior. The Figures illustrate the pin 61c sitting within the cutout 63a and pawl tooth 61b disengaged from the ratchet wheel 59. When the knob 5 is pushed to position B and tI-IZIRURU

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turned CCW, the cam 63 is driven (via gears 47d, 65) to turn CCW. The cam is profiled to drive the pin 61c out of the cutout 63a. This turns the arm 61 CW about the axis 61a to engage the pawl 61b with the ratchet wheel 59. This restrains the ratchet wheel 59, and in turn the gear 55, against the rotation urged by the spring 3 (via shaft 27, pawl member 51 and ring 53). The ratchet wheel is profiled so the torque outwardly urges the pawl 61b and in turn urges the pin 61c toward the shaft 27 so as to maintain contact with the cam 63.

The pin 61c is a cam follower arranged to follow the timing cam 63. When the cam is turning, the pin 61c rides relatively along the round exterior portion until the cutout 63a moves into alignment with the pin 61c whereupon the pin 61c falls into the cutout and the pawl 61b retreats thus freeing the ratchet wheel 59 to rotate CCW whereby the deactivation spring portion 3a is released to rotate the shaft 27, pawl member 51 and ring 53 CW in unison.

Returning to Figures 13 and 17, the rotating shaft 27 turns the pin 57a of the disk 57 to engage the end of the slot 37c and thereby the turn the drive member 37 and the input shaft inside the drive member to deactivate the stove.

The timing cam 63 is a key component of the mechanical timer 7. The angular orientation of the cam 63 corresponds to the remaining timer period. The timer spring portion 3b, escapement 7a, gear train 7b, shaft 47d and gears 47c, 65 together constitute a drive of the mechanical timer 7. The drive turns the cam 63 at a regulated rate until the trigger point is reached. Preferably the rate is substantially constant although there are other options. In this example, the trigger point is the point at which the pin 61c falls into the cutout 63a. Other forms of drives and triggers are possible.

A mechanical (i.e. battery-less) timer advantageously provides for reliable longevity without the risk of failure due to battery failure. Preferably the control system 1 is entirely battery-less. In this example the escapement 7a is a lever escapement, although other escapements and other mechanical timers more generally are possible.

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The constraint system by which the rotation of cam 63 and gear 65 relative to the shaft 27 is constrained is now described. The gear 65 carries an eccentric stop in the form of an upwardly projecting pin 65a (Figures 6 and 7). Arm 67 is fixed relative to the shaft 27 and extends outwardly therefrom to abut the pin 65a and thereby limit the rotation of cam 63 and gear 65 with respect to the shaft 27.

The gear 65 is constrained to move through a limited range of motion. In this example, the gear 65 has a toothed perimeter interrupted by an outwardly extending stop 65b. The stop 65b is positioned to abut the gear 47c to limit clockwise movement of the gear 65. Figures 6 and 7 show elements of the control system 1 in their deactivated configuration. Features 47c, 65a, 65b, 67 are key features of a stop system that limits the CW rotation of the shaft 27 to ensure that the deactivation spring portion 3c does not fully relax. This helps to ensure that the deactivation spring portion 3c is worked through a range of motion in which spring force adequate to turn the input shaft IS provided.

A restraint 69 (Figures 11 and 17) restrains knob 5 against turning away from its deactivated position to reduce the risk of inadvertently turning input shaft IS. Preferred forms of the restraint are automatically engaged during the deactivation sequence of the control system 1. In this way the described control system 1 advantageously converts the relevant burner from a 2-stage knob system to a 3 stage knob system.

This example of the restraint 69 comprises a plunger 69a and spring 69b by which the plunger is spring-loaded to engage the knob 5. In this case the plunger 69a and spring 69b are mounted atop the middle plate 29. The plunger 69a engages an upright groove 69c on the inside of the peripheral wall of the knob 5 to rotationally fix the knob 5.

The plunger 69a and the groove 69c have complementary forms that cooperate, as the knob 5 is pressed from position A to position B, to inwardly drive the plunger, against the spring 69b, out of the groove 69c. In this case each of the plunger 69a and the groove 69c has a ramp facing the other's ramp for this purpose. In this way tI-IZIRURU

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the restraint is disengaged and the knob 5 is connected to the mechanical timer 7 by a single movement (depressing the knob) to make for simple intuitive operation.

Other disengagement mechanisms are possible, e.g. the knob 5 might carry a button radially pressable to drive the plunger 69a from the groove 69c. Indeed other restraints more generally are possible, e.g. a top of the shaft 41b might nest within a radial groove in the ceiling of the knob 5 and the knob 5 might carry a button downwardly pressable to downwardly drive the shaft 41b from that groove to simultaneously disengage the restraint and connect the knob to the mechanical timer 7.

When the stove burner is inactive the knob 5 sits up at position A whereat it is guarded by restraint 69 against inadvertent rotation. To turn on the burner, the knob 5 is pushed down to position B and turned 1 turn CCW to cause gas to flow, load spring portions 3a, 3b and turn the mechanical timer to its maximum time period (e.g. 1 hour). The knob 5 is then depressed to ignite the gas. The knob 5 is then released to enable it to return to position A so that gear 41a disengages gears 39b, 43a (Figures 13 and 20) to decouple the knob 5 from the mechanical timer 7. The knobs 5, 9 can then be turned independently to independently adjust the temperature (i.e. gas flow rate) and the timer period.

If the operator then forgets about the stove, the deactivation mechanism is there as a backup to automatically turn the burner off after the time period. On the other hand, at any point during the timer period, the burner can be deactivated by turning the knob 5 CW in a manner that is simple and intuitive and feels familiar from conventional gas stove knobs. The user might press the knob 5 to position B then turn the knob to simultaneously turn off the gas and move the mechanical timer to its deactivation configuration. Alternatively the user might simply turn the knob 5 then either turn the knob 9 or simply allow the timer to run its course.

The invention is not limited to the details exemplified herein. Rather the invention is defined by the claims. Many useful variants of the technologies disclosed herein are possible. By way of example, the construction of the timer might be simplified by replacing the knob 9 with a smaller top-mounted knob fixed with respect to the shaft tI-IZIRURU

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47d. This would eliminate the gear train 43. Indeed a simple timing and automatic deactivation mechanism that is wound and set independently of a temperature control knob would be useful.

The term 'comprises' and its grammatical variants has a meaning that is determined by the context in which it appears. Accordingly, the term should not be interpreted exhaustively unless the context dictates so.

Claims (13)

tI-IZIRURU 16 CLAIMS

1. A mechanical control system for a heating system;

the heating system having an exterior and an input member turn-able, relative to the exterior, to vary a temperature of the heating system and to deactivate the heating system;

the mechanical control system comprising

a deactivation spring portion for turning the input member;

a first turning portion user-turnable to load the deactivation spring portion;

a mechanical timer to restrain the deactivation spring portion for a timer period then release the deactivation spring portion to turn the input member to deactivate the heating system.

2. The mechanical control system of claim 1 having

a winding configuration in which the first turning portion is user-turnable to load the deactivation spring portion;

a temperature-adjusting configuration in which the first turning portion is turn-able, to turn the input member to adjust the temperature.

3. The mechanical control system of claim 1 wherein the first turning portion is axially movable

from a winding position in which the first turning portion is user-turnable to load the deactivation spring portion;

to a temperature-adjusting position in which the first turning portion is turnable, to turn the input member to adjust the temperature.

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4. The mechanical control system of claim 1, 2 or 3 wherein the first turning portion is axially movable to an ignition position to depress the input member to ignite the heating system.

5. The mechanical control system of any one of claims 1 to 4 comprising a second turning portion user-turnable to adjust the timer period.

6. The mechanical control system of any one of claims 1 to 5 comprising a timer spring portion for powering the timer mechanism;

the first turning portion is user-turnable to load the timer spring portion.

7. The mechanical control system of any one of claims 1 to 6 predominantly consisting of a unit retrofittable to the heating system.

8. The mechanical control system of claim 7 comprising one or more adhesive portions by which the unit is attachable to the exterior of the heating apparatus.

9. The mechanical control system of any one of claims 1 to 8 comprising a restraint for restraining the first turning portion against turning when the heating system is deactivated.

10. The mechanical control system of the claim 9 wherein the first turning portion is axially movable to disengage the restraint.

11. The mechanical control system of any one of claims 1 to 10 wherein the input member is a stub shaft and the mechanical control system comprises a socket to fit over the stub shaft.

12. The mechanical control system of any one of claims 1 to 11 wherein the heating system is a portion of a gas cooking appliance.

13. The mechanical control system of any one of claims 1 to 12 and the heating system.

5

9 11 13 1/8

E

FIG 1

5 5 5

9 9 9

A B FIG 2 C 2/8

25 15 15 15

23 31 33 33 21 29 19 35 33 11

A B C FIG 3

B B K K C C D D

FIG 4a 3,3a 27 47d a 27 65 65 67 27 3/8

65b 65b

47a 3b 65a 47c 65a 29 SECTION B-B SECTION K-K SECTION C-C SECTION D-D FIG 5 FIG 6 FIG 7 FIG 8

F F G G H H

53 51 63 FIG 4b 69b 61b 59 69,69a 61c 27 61 55 61a 4/8

7a

7 47d 31a 63a 27 7b 7b 1 31 SECTION F-F SECTION G-G SECTION H-H FIG 9 FIG 10 FIG 11

J J I I

45a 39b 39b 41a FIG 4c 41a 5/8

43a 45a

43,43a

43b 37

43c 37c 45 57a 43d SECTION I-I SECTION J-J FIG 12 FIG 13

P R

Q M M Q P SECTION R-R FIG 18 25 R 6/8

FIG 14 41b 39,39a 27 25 15 57 25a 39c 5,17 39b 69,69a 41,41a 33 37c 69c 29 29 37b 37b 9 11a 11 41b' 37 37,37a IS 13 SECTION M-M SECTION P-P SECTION Q-Q FIG 15 FIG 16 FIG 17

25 15 25b

25a 23

31

51,53 21

47b 29 19 7/8

11

13

37,37b FIG 19

47b 41b 47d 47 47c 47a 41,41a

39b 37b 8/8

43b 43a

FIG 20