GB2301882A - Cooker - Google Patents

Abstract

A cooker having a combined oven and grill cavity 1 has a control knob 13 operating on a control 12 which is such that rotation in one direction switches on a grill burner 5 and operation in the other direction switches on a heater 6 for operation in the oven mode. The control is coupled to a flap 10 via means such as a push rod 11 such that when the control is operated in a grill mode, the flap 10 remains open, so that the larger flue consisting of apertures 7 and 8 (communicating with 9) are available, whereas when the control 12 is operated in an oven mode, the flap 10 automatically closes the opening 9 and hence opening 8 so that only the smaller opening 7 appropriate to the oven mode is selected.

Description

COOKER This invention relates to cookers.

The invention provides a cooker having a combined oven and grill assembly, comprising heating means for the cavity for operation in the oven mode, a gas-powered grill for the cavity, flue means for the exhaust of combustion products from the cavity, a control rotatable in one direction to operate the oven heating means and in the opposite direction to operate the grill, and a flap which is so coupled to the control as to be movable to restrict the flue means in response to rotation of the control in the oven mode direction.

Coupling of the flap to the control ensures that the larger flue area appropriate to operation in the grill mode is restricted when cooking in the oven mode takes place, thereby preventing unsatisfactory cooking conditions.

The flap may be resiliently biased into a position in which it does not restrict the flue means.

The flap may be coupled to the control via a cam which extends around the curved periphery of the control. The use of such an edge cam engenders flexibility in the operations which can be performed by the cam. The region inside the curved periphery may be hollow, in order to accommodate components such as gas valves and electric switches, to provide a more compact arrangement of parts. The cam may include two cam surfaces arranged to cause, via respective cam followers, successive axial movements of a slider, in respor-o to rotation of the control through corresponding angular regions, to move the flap to restrict the flue means. The use of such a two-start cam permits a greater axial movement of the slider for a given axial depth of cam.The cam may also include a cam surface opposed to a flue-means-restricting cam surface, in order to ensure that the flue means is returned to its unrestricted condition when the control is returned to its starting position from the oven mode position. The cam may further include a notch arranged to co-operate with a cam follower to prevent rotation of the control out of its starting position (i.e. lock it) in the event of movement of the flap in a flue-means-restricting direction when the control knob is in a starting position. Such a movement of the flap in a flue-means-restricting direction would take place if the flap was biased open resiliently, and if those resilient means broke or became overridden by friction.

A gas cooker having a combined oven and grill cavity constructed in accordance with the invention will now be described by way of example with reference to the accompanying drawings, in which: Figure 1 is a side, sectional view, partly in schematic form, of the cooker; Figure 2 shows the control and the flap of Figure 1 in more detail; Figure 3a is an end view of the oven/grill control, with the control in the "off' position; Figure 3b is a side view of the control shown in Figure 3a, with the cam follower and slider being shown in a displaced position; Figure 3c is a plan view of the control shown in Figure 3a, with the control having been turned to a "grill on" position; Figure 3d is a plan view of the control shown in Figure 3a, with the control having been turned to an "oven on" position;; Figure 3e is side view of the control, corresponding to the view of Figure 3b, but illustrating the condition in which the resilient means has broken; and Figures 3f and 3g are side views of the control, corresponding to the view of Figure 3b, illustrating conditions when one of the cam followers has broken.

Referring to Figure 1, the gas cooker has a combined oven and grill cavity 1 closed by a door 2 and a main oven cavity 3 closed by a door 4. The cooker may be an underbench applianc,, ol it may be a free-standing cooker provided with a hob, which is not shown. The oven/grill cavity 1 is provided with a gas burner 5 (shown schematically) for operation in the grill mode and a burner 6 (shown schematically) for operation in the oven mode. The main oven cavity 3 is also provided with a gas burner which is not shown.

The combined oven/gnll cavity 1 is provided with flue means in the form of a relatively small opening or group of openings 7, appropriate to conditions when the bumer 6 alone is in operation and a larger opening 8, appropriate in conjunction with the opening 7 to conditions when the burner 5 for the grill is in operation (usually this will be with the oven/grill cavity door 2 being open). The opening 8 leads to a channel provided with an opening 9, which in turn is closable by a flap 10. The flap 10 is controlled by a push rod 11 from a control 12, the shaft of which carries an operating knob 13.

The control 13 is turned in a clockwise direction to operate valves to set the burner 5 into operation and in an anti-clockwise direction to operate valves to set the burner 6 into operation. In the latter case, the control knob is also responsible, via the push rod 11, for closing the opening 9 by means of the flap 10, and hence the opening 8, thereby restricting the flue means to the aperture 7 to provide appropriate cooking conditions for the oven mode.

The closure of the opening 9 by the flap 10 is shown in more detail in Figure 2, where it will be seen that the flap 10 has a lug l0a connecting it to the push rod 11, and is pivoted about an axis 14. The control 12 includes a fixed bracket 15 through which the end of the push rod 11 extends, having been bent through an angle. Resilient means in the form of a spring 16 is compressed between a flange 15a on the end of the bracket 15 and a cross pin 1 lea which is secured to the push rod 11. The push rod 11 terminates in a slider 17, which is locked to the push rod by means of a set screw.

The compressed spring urges the cross pin 11 a away from the flange 15a and thus the push rod 11 into the illustrated position in which the flap 10a is resiliently held open.

The cam of the control 12 will now be described by reference to Figures 3a to 3g.

Referring to Figures 3a and 3b, the cam 18 is an edge cam i.e. it extends from the edge of the peripheral surface of the cam, and is a two-start cam, in the sense that cam surfaces 1 8a and 1 8b are successively responsible for axial displacement of the slider 17 via respective cam followers 17a, 17b. The slider is mounted for slidable movement (Figure 3a) in the axial direction of the bent end portion of the push rod 11. In Figure 3b, the ends of the cam followers 17a, 17b are shown in the position they would adopt on the cam, but the slider 17 with cam followers 17a, 17b is also shown underneath the cam 18, rotationally displaced through 90 , for the sake of clarity.

It will be noted that the cam follower 1 7a is held against the cam surface 18a, by virtue of the spring 16.

The state of the cam illustrated in Figure 3a and in Figure 3b, remembering that the dots 17a and 17b shown on the cam show the correct position of the followers, corresponds to the control being in the off position.

When the control is turned in a clockwise direction to turn the grill on, as shown in Figure 3c, the slider 17 does not move in an axial direction since it runs along flat section of cam surface 18c. Given that no axial movement of the slider 17 takes place, no axial movement of the push rod 11 takes place, and the flap 10 remains in its open position because of the spring 16. Thus, the full area of the flue means 7, 8 is available, corresponding to the greater amount of combustion products being generated by the grill, which is in any case advisably operated with the oven/grill cavity door 2 open.

When the control is turned in an anti-~lockw.se direction to turn the oven on, as shown in Figure 3d, the cam follower 17 first of all encounters the curved cam surface 18a, thereby driving the slider 17 in a left hand direction as seen in Figure 3b. When the cam follower reaches the notch 1 8d the inclined surface 1 8a has come to an end, but further axial movement of the slider takes place by virtue of the cam follower 1 7b being driven down the inclined cam surface 18b. Axial movement of the slider 17 ceases when the cam follower 17b has run onto the flat section of the cam 18e.Because of the axial movement of the slider 17, the bent portion of the push rod has been axially displaced, and the push rod 11 has been moved left as seen in Figure 2 in order that the flap 10 closes the aperture 10, resting on the seal lOb in the process. The flue means has been restricted to the aperture 7, appropriate to the operation of the oven/grill cavity in the oven mode. In this mode the door 2 will of course be shut.

Thus, it will be seen that the control 12 with its cam 18 is responsible for closing the flap 10 in the appropriate mode. Gas valves and optional igniting means (not shown) are also operated by the same rotation of the control 12. The incline on the cam surfaces 18a, 1 8b is relatively steep, in order that the flap 10 is closed before the ignition of the burner 6 is operated. The fact that there are two cam surfaces 18a, 1 8b enables this steep incline to be achieved without a correspondingly deep control, because of course space is at a premium in this region of the cooker. The cam 18 is hollow in the centre, and gas and associated electric controls are housed in this region to further utilise the space in an effective way.

Referring to Figures 3e to 3g, various safety features are built into the cam. Thus, firstly, if the spring 16 breaks, or if after operating the oven sufficient friction has finally built up in the hinge 14 that it overrides the spring, the potentially dangerous situation of the flap 10 being closed with the grill in operation must be avoided. This is accomplished by means of cam surface 1 8f which is opposed to cam surface 18b, and drives cam follower 17 in a direction causing opening of the flap when the control 12 is operated in a clockwise direction to turn the oven off. Thus the flap 10 cannot be closed when the grill is next used. In the two possible circumstances envisaged, i.e. sticking of the hinge 14 and breaking of the spring 16, in the case of the former the control 12 will operate the flap as needed.In the case of the latter, when the control 18 returns to its central off position, the weight of the flap will cause the slider 17 to move downwardly, and the effect of this will be that the cam followers 17a, 17b move to the left as seen in Figure 3e. It will be noted that cam follower 17b is now trapped in a notch 18g which completely locks the gas control in a safe i.e. off position, indicating that a service call is required. The lower face of the notch 1 8g as seen in Figure 3e has an upwardly profiled right hand lower end as seen in Figure 3e, so that if the follower 17b is not fully in the notch 18g, waggling of the control will drive it fully into the notch 18g.In the event of siseanng of the follower 17b, a similar blocking of the knob 12 would be effected by the notch 1 8d on the one hand and surface 1 8h on the other hand, with regard to follower 17a.

Assuming the spring 16 remains in operation, but one of the followers 17a, 17b shears off, if the follower 1 7a shears off, then the flap 10 will not be closed at all because the initial depression of the slider cannot take place because there is nothing to run down the inclined surface 18a. Thus the oven will operate with the flap open, and inappropriate ventilation should alert the user to the need for a service call. If the grill is selected, this will operate safely. If the right hand follower 17b breaks, once again the grill can be operated perfectly safely but, if the oven is selected, this time the flap 10 is partially closed by virtue of the running of the follower 1 7a down the inclined surface 18a.

However the notch 1 8d then captures the follower 1 7a and locks it, alerting the user to the breakage and necessitating a service call. The follower 17a meets the notch 18d before any gas valves are opened.

Of course variations may be made without departing from the scope of the invention.

Thus, the main oven need not be gas, but it could be electric or microwave, or it could even serve some other function e.g. as a dishwasher. The appliance could if desired consist solely of the cavity 2. Further, the oven mode of the oven/grill cavity could be by means of electric heating means instead of the gas burner 6.

Claims (7)

1. A cooker having a combined oven and grill assembly, comprising heating means for the cavity for operation in the oven mode, a gas-powered grill for the cavity, flue means for the exhaust of combustion products from the cavity, a control rotatable in one direction to operate the oven heating means and in the opposite direction to operate the grill, and a flap which is so coupled to the control as to be movable to restrict the flue means in response to rotation of the control in the oven mode direction.

2. A cooker as claimed in claim 1, in which the flap is coupled to the control via a cam which extends around the curved periphery of the control.

3. A cooker as claimed in claim 2, in which the cam includes two cam surfaces arranged to cause, via respective cam followers, successive axial movements of a slider, in response to rotation of the control knob through corresponding angular regions, to move the flap to restrict the flue means.

4. A cooker as claimed in claims 2 or 3, in which the cam includes a cam surface opposed to a flue-means-restricting cam surface, in order to ensure that the flue means is returned to its unrestricted condition when the control is retumed to its starting position from the oven mode position.

5. A cooker as claimed in any one of claims 2 to 4, in which the cam includes a notch arranged to co-operate with a cam follower to prevent rotation of the control out of its starting position in the event of movement of the flap in a flue-means-restricting direction when the control is in its starting position.

6. A cooker as claimed in any one of claims 1 to 5, in which the flap is resiliently biased into a position in which it does not restrict the flue means.

7. A cooker substantially as herein described with reference to the accompanying drawings.