Description Timed knob for gas cooking appliances The present patent application for industrial invention relates to a timed knob for gas cooking appliances.

The knob according to the present invention is a complete innovation, since so far no knob has been provided with a device for automatic turning off after a set time-unlike electrical or microwave ovens that are traditionally provided with timer.

The present invention has been devised as a solution to a problem commonly experienced by all users of gas cooking appliances. Once the stove has been turned on and the heat adjusted, it is necessary to check the passing of time, in order to turn off the stove and avoid burning the food.

This means that users cannot carry out any other activity while cooking or leave the house with no time limits once the stove has been turned on.

The purpose of the present invention is to realise a time knob for gas cooking appliances, which allows the user to select between two different operating modes: manual or automatic turning off of the knob (the latter after the set time).

Another purpose of the present invention is to realise a knob as indicated above capable of being installed in new gas cooktops, which can also replace the traditional knobs of the existing cooktops.

Basically, the knob according to the present invention comprises a first knob used to open and close the gas valve of each stove. The first knob includes a boss-same as the boss of the traditional knobs of known type currently installed in gas cooking appliances-on which the manoeuvring pin of the gas valve can be inserted.

To close the gas valve, the knob can be rotated either manually or automatically. In the latter case, the knob is dragged by a mechanism actuated by a spiral spring that must be manually charged before opening the gas valve. The first knob incorporates a second knob, hereinafter defined as

"programming knob", used to set the time interval for the automatic disengagement of the ratchet gear that prevents the free spontaneous discharge of the spiral spring.

The structural configuration and the operating modes of the knob according to the present invention will become evident from the following description with reference to the enclosed drawings, which are intended for purposes of illustration only and not in a limiting sense, whereby: -Fig. 1 is an exploded drawing and an axomometric view of all the components of the timed knob according to the present invention ; -Fig. 2 is a cross-section with an axial plane of the knob according to the present invention with deactivated timer; -Fig. 3 is a cross-section with an axial plane of the knob according to the present invention with activated timer; -Fig. 4A and 4B are an axonometric view and a side view, respectively, of the time programming device used to turn off the knob according to the present invention. These two figures show the position of the device with deactivated timer; -Fig. 5A and 5B are an axonometric view and a side view, respectively, of the time programming device used to turn off the knob according to the present invention. These two figures show the position of the device with activated timer; -Fig. 6 is an axonometric view of the knob according to the present invention applied on a vertical support plate.

With reference to the aforesaid figures, the knob according to the present invention comprises a first knob (1) used to open and close the gas valve, which is internally hollow in order to house a second programming knob (2) with built-in timer (3).

The timer (3), which can also be provided with ringer, is of known type and can be easily found on the market.

The first knob (1) internally features a central pin (1a) with square cross-section, which is coupled with the timer (3), thus acting as charging pin for the timer. The first knob (1) externally features a central collar (1b) with

faceted internal hole (F), in which the faceted manoeuvring pin (P) used to open and close the gas valve is inserted.

The pin (P) is the same pin that is traditionally used in the gas valves installed in cooktops. This means that the timed knob according to the present invention can be installed on the existing gas cooking appliances without requiring any prior modification.

The back wall (1c) of the knob (1) features a wide opening (1d) that extends for more than 180°. The external edge of the opening has a tooth (1e) with a hole (1 , whose function will be hereinafter explained.

The opening of the programming knob (2) features an annular groove (2a), in which a semicircular plate (4) is housed and slides. The semicircular plate (4) features a central hole (4a), a peripheral tab (4b) protruding from the side that faces the inside of the second knob (2) and a peripheral pin (4c) protruding from the side that faces the back wall (1 c) of the first knob (1).

When the knob (1) is coupled with the knob (2), the semicircular plate (4) is inserted in the pin (1a), which, in turn, is coupled in a prismatic way with the square housing (3a) located in the middle of the timer (3) contained in the knob (2).

A specially shaped lever (6) is located in the annular space (5) between the external circular wall of the second knob (2) and the internal circular wall of the first knob (1). The lever (6) features a central pin (6a), which ends with a lateral tooth (6b) in the front and a curved paddle (6c) in the back.

The lever (6) is hooked to the first knob (1) so that the central pin (6a) is inserted into the hole (1 of the tooth (1e), the curved paddle (6c) remains inside the space (5) and the lateral tooth (6b) protrudes with respect to the back wall (1c) of the first knob (1).

A box (7) is inserted on the collar (1b) of the first knob (1). The box (7) is inserted and fixed to the plate (8) normally used in cooktops to house the gas opening and closing knob. The plate (8) usually bears the reference symbols that indicate the various levels of the heat and the closing point of the gas valve.

More precisely, the box (7) comprises a circular element (7a) that contains a spiral spring (9) and is closed with a circular lid (7b). The element (7) features a central hole in which a collar (10) is inserted, turning freely. The front of the collar (10) features a hole (10a) suitable for receiving the tip of the pin (4c), while the circular edge of the collar (10) features a saw toothed profile (10b).

The collar (10) is part of a sleeve (10c) inserted into the box (7)-as shown in Fig. 2 and 3. The internal end of the spiral spring (9) is fixed to the turning sleeve (10c), while the other end is hooked to the fixed lid (7b).

Following is the description of the timed knob according to the present invention starting from its idle position (that is with the gas valve in closed position).

In this stage (see Fig. 2,4A and 4B), the spring (9) is not charged, the pin (4c) is not inserted into the hole (10a) of the collar (5), the timer (3) is not charged, the tooth (6b) of the lever (6) does not engage with the toothed profile (10b) of the collar (10), and the paddle (6c) of the lever (6) is inserted into a notch (2b) located on the external surface of the second knob (2).

To open the valve without programming the timed turning off of the knob, the user must simply rotate in anti-clockwise direction the first knob (1), to which the pin (P) of the gas valve is coupled.

The knob (1) drags the semicircular plate (4) due to the interference between the pin (4c) of the plate (4) and the back wall (1c) of the knob (1).

The second knob (2) remains still since the semicircular plate (4) slides freely inside the annular groove (2a) located on the opening of the second knob (2).

Also the collar (10) remains still since the pin (4c) of the semicircular plate (4) does not engage inside the hole (10a) of the collar (10).

To program the turning off of the knob (1), the user must first use the knob (2) to charge the spring (9) and the timer (3), then set the time for the automatic turning off of the knob (1) with the knob (2) and finally open the knob (1) to adjust the heat as needed.

To charge the spring (9), the user must push the second knob (2)

forward (see fig. 3) to engage the pin (4c) inside the hole (10a) of the collar (10) and the rotate the knob (2) in anti-clockwise direction by 180° to drag the collar (10) in the same rotation. This causes the charge of the spring (9), since one end of the spring (9) is fixed to the lid (7b) and the other end is hooked to the collar (10). It must be noted that the knob (2) is capable of dragging the plate (4) in rotation thanks to an internal projection (2c) located in the opening and designed to interfere with the tab (4b).

Although it is subject to the thrust of the charged spring (9), the collar (10) cannot rotate freely, since it is locked by the tooth (6b) of the lever (6), which is pressed against the toothed profile (10b) of the collar.

The pressure is ensured by the flexion imposed on the lever (6) during the anti-clockwise rotation of the knob (2), which determines the ejection of the paddle (6c) from its housing (2b) (see Fig. 5b). This makes the lever (6) fold, since the same is centrally pivoted in the hole (1 of the knob (1), which remains still during the anti-clockwise rotation of the knob (2).

By pushing the knob (2) forward, the pin (1a) of the knob (1)-which is temporarily still-is coupled to the hole (3a) of the timer (3). Therefore, beside charging the spring (9), the anti-clockwise rotation of the knob (2) determines the simultaneous charge of the internal mechanism of the timer (3), whose external shell starts rotating together with the knob (2), to which it is joined.

Once the spring (9) and the timer (3) have been charged, the knob (2) can be rotated in clockwise direction, setting the time for the automatic turning off of the knob (1) (see Fig. 6). To this end, it must be noted that the programming minutes (M) are shown on the edge of the knob (2), while the knob (1) features a reference mark (Z) for zero (see Fig. 6).

During the rotation of the knob (2) first in anti-clockwise and then clockwise direction, the paddle (6c) touches against the external surface of the knob (2), keeping the tooth (6b) pressed against the toothed profile (10b).

The plate (4) does not follow the knob (2) in its backward rotation since the interference between the projection (2c) and the tab (4b) takes place only in case of anti-clockwise rotation of the knob (2).

Once the knob (2) has been stopped on the desired programming time,

the gas valve can be opened with the knob (1) as indicated above.

During the anti-clockwise rotation of the knob (1), the tooth (6b) moves along the toothed profile (10b), always pressed against it, until the paddle (6c) is ejected from its housing (2b).

It must be noted that the paddle (6c) can be inserted into the notch (2b) only after the set time has elapsed.

In fact, the slow rotation of the timer (3) drags into rotation the knob (2), which is fixed to it. Once the set time has elapsed, the notch (2b) matches the paddle (6c). The paddle (6c) snaps, thus removing the tooth (6b) from the toothed profile (10b) of the collar (10). Being now free, the collar starts rotating under the thrust of the spring (9) during discharge.

The collar (10) drags the plate (4), whose pin (4c) is engaged inside the hole (1a) of the collar. The plate (4), in turn, drags the knob (1) due to the interference between the pin (4c) and the back wall (1c) of the knob (1), which is automatically closed when the set time has elapsed.