Patent Description:
In cooking appliances, shafts are extending in the direction away from the control panel. The control knobs, provided on the shafts, are rotated and the power level of the heat source of the cooking appliance can be controlled. Since most of the control knobs are connected to the shafts without any locking mechanism, control knobs can be easily removed from the shafts.

Users can sometimes unintentionally apply more force to the control knobs than necessary. In such cases, control knobs may be disengaged by the shaft as a result of this random force. Thus, there is a need for a locking mechanism that enhances the safety of the cooking appliances.

A prior art publication in the technical field of the invention may be referred to as <CIT>, which discloses a knob, a fastening device, and a shaft. The fastening device is used for knob detaching force required being greater than the incidental removal force exerted to prevent undesired separation of the knob from the shaft.

A control knob according to the preamble of claim <NUM> is disclosed in prior art document <CIT>. For detachably coupling the control control knob with a valve shaft, it comprises a snap element being designed for forming a snap lock together with the valve shaft.

Prior art document <CIT> discloses a cooking appliance wherein a knob collar (<NUM>; <NUM>) is removably mounted on the shaft (<NUM>) and placed between the control panel (<NUM>) and the knob body (<NUM>).

The invention provides an additional improvement to the prior art.

An object of the present invention is to provide a control knob which is prevented from being easily removed during normal use and which is nevertheless simply demountable from the shaft, if needed.

The present invention proposes a cooking appliance comprising a main body, a control panel provided on the main body, a switch for adjusting a power level of a heat source, the switch comprising a shaft extending through the control panel, and a control knob connected to the shaft for rotating the shaft, wherein said control knob comprising a knob body having a guiding portion in which the shaft is arranged to extend. The cooking appliance can be a freestanding cooking appliance. The guiding portion is made of elastic material, preferably plastic material. The guiding portion is provided with at least one protrusion, the shaft is provided with at least one corresponding recess, both of the protrusion and the recess are being sized and shaped to engage each other at a locked position so that knob body and shaft rotate together. At the locked position, since the protrusion and the recess are engaged with each other, the knob body is prevented from moving slidably on the shaft. Therefore, when the user pulls the knob body at a locked position, the knob body is prevented from being removed from the shaft. This enables eliminating the safety problems likely to occur due to the control knob being removed from the shaft as a result of incidental removal force.

The shaft is provided with at least one pushing hole as a through-hole which enables the guiding portion is accessed when the knob body is at the locked position. The pushing hole makes it easier to push the guiding portion when the knob body is in the locked position.

The guiding portion has a pushing end facing the pushing hole at the shaft when the knob body is at the locked position.

In a possible embodiment, the cooking appliance comprises a gas tap which is connected to the shaft. The cooking appliance can be a gas cooking appliance.

In a possible embodiment, a knob collar is removably mounted on the shaft. Thus, when the user desires to change the knob collar, the user can remove the knob collar from the shaft without damaging it. Knob collar placed between the control panel and the knob body.

In a possible embodiment, a slot in which the knob body is partly positioned inside is disposed on the inner face of the knob collar. Thus, mounting the control knob to the knob collar is simplified.

In a possible embodiment, the knob collar is slidably movable on the shaft between a first position in which it hides the pushing hole and a second position in which it allows access to the pushing hole. Thus, the appearance of the cooking appliance is improved.

In a possible embodiment, a resilience member is disposed between the knob body and the knob collar so that the knob body is movable relative to the knob collar by manipulating against the force of the resilience member. The resilience member can be a spring, in particular a helical spring.

In a possible embodiment, the recess has a polygonal cross-section, preferably rectangular. Thus, the protrusion inserts into the recess easily.

In a possible embodiment, the protrusion has at least a partly inclined portion which is inclined with respect to the longitudinal axis of the knob body. Thus, the protrusion is prevented from being damaged during the disengaging from the recess.

In a possible embodiment, the knob body has at least two slits that partly extend along the guiding portion. Thus, the flexibility of the guiding portion is increased.

In a possible embodiment, an indicator in the form of a lengthwise recess is provided on the knob body. Thus, the user can detect the heat level easily by using the knob body and the control panel.

Furthermore, the present invention provides a method of mounting a control knob on a shaft of a cooking appliance comprising the steps of providing the cooking appliance wherein the cooking appliance comprises a main body; a control panel provided on the main body, and a switch having a shaft extending through the control panel for adjusting a power level of a heat source; creating a recess on the shaft of the switch; providing a control knob wherein the control knob has a guiding portion in which the shaft is arranged to extend, and the guiding portion having at least one protrusion shaped and dimensioned with respect to the recess on the shaft and mounting the control knob to the shaft such that the protrusion and the recess engage each other at a locked position in which the control knob and the shaft rotate together. Thus, the knob body is prevented from moving slidably on the shaft. The method of mounting a control knob on a shaft of a cooking appliance comprising further the step of creating at least one pushing hole on the shaft as a through-hole which enables the guiding portion is accessed when the knob body is at the locked position; providing a pushing end on the guiding portion facing the pushing hole at the shaft when the knob body is at the locked position. The pushing hole enables the user can access to the guiding portion when the knob body is in the locked position.

In a possible embodiment, a method of mounting a control knob on a shaft of a cooking appliance comprising further the step of pushing the pushing end of the guiding portion by inserting a tool into the pushing hole to disengage the protrusion from the recess when demounting is needed. Thus, the demounting is simplified.

The accompanying drawings are given solely for the purpose of exemplifying the invention whose advantages over prior art were outlined above and will be explained in detail hereinafter:.

The present invention proposes a cooking appliance (<NUM>) comprising a main body (<NUM>), a control panel (<NUM>) provided on the main body (<NUM>), a switch (<NUM>) for adjusting a power level of a heat source, the switch (<NUM>) comprising a shaft (<NUM>) extending through the control panel (<NUM>) and a control knob (<NUM>) connected to the shaft (<NUM>) for rotating the shaft (<NUM>), wherein said control knob (<NUM>) comprising a knob body (<NUM>) having a guiding portion (<NUM>) in which the shaft (<NUM>) is arranged to extend. Referring to <FIG>, the control panel (<NUM>) is provided on the main body (<NUM>). The control knob (<NUM>) is disposed on the control panel (<NUM>). The guiding portion (<NUM>) is provided with at least one protrusion (<NUM>), the shaft (<NUM>) is provided with at least one corresponding recess (<NUM>) and both the protrusion (<NUM>) and the recess (<NUM>) are being sized and shaped to engage each other at a locked position so that knob body (<NUM>) and shaft (<NUM>) rotate together. As seen in <FIG>, the protrusion (<NUM>) is formed on the upper part of the guiding portion. The shaft (<NUM>) is inserted into the guiding portion (<NUM>). As seen in <FIG>, the recess (<NUM>) is formed on the lower part of the shaft (<NUM>). When the protrusion (<NUM>) and the recess (<NUM>) are engaged to each other, the knob body (<NUM>) is connected to the shaft (<NUM>). When the knob body (<NUM>) is slided on the shaft (<NUM>) fully, the knob body (<NUM>) is brought to the locked position. Since the protrusion (<NUM>) is inserted into the recess (<NUM>) when the knob body (<NUM>) is at a locked position, the knob body (<NUM>) is prevented from moving horizontally on the shaft (<NUM>).

Referring to <FIG>, the shaft (<NUM>) is provided with at least one pushing hole (<NUM>) as a through-hole which enables the guiding portion (<NUM>) is accessed when the knob body (<NUM>) is at the locked position. The pushing hole (<NUM>) is formed on the part of the shaft (<NUM>) extending out of the control panel (<NUM>) wherein the pushing hole (<NUM>) is closer to the control panel (<NUM>) than the recess (<NUM>). Therefore, the pushing hole (<NUM>) enables the user access to the guiding portion (<NUM>) when the knob body (<NUM>) is at the locked position.

As seen in <FIG>, the shaft (<NUM>) is positioned inside the guiding portion (<NUM>). The knob body (<NUM>) can be brought into a locked position in which the protrusion (<NUM>) and the recess (<NUM>) are engaged with each other. Thus, the knob body (<NUM>) and the shaft (<NUM>) are connected and able to rotate together. The knob body (<NUM>) can also be brought into an unlocked position in which the protrusion (<NUM>) and the recess (<NUM>) are not engaged with each other. The user can push the guiding portion (<NUM>) through the pushing hole (<NUM>) by using a tool or his/her hand. By applying force onto the guiding portion (<NUM>), the guiding portion (<NUM>) stretches downwardly. For example, when demounting is needed, pushing a pushing end (<NUM>) of the guiding portion (<NUM>) by inserting a tool into the pushing hole (<NUM>) helps to disengage the protrusion (<NUM>) from the recess (<NUM>). When the guiding portion (<NUM>) is pushed downwardly, the protrusion (<NUM>) comes out of the recess (<NUM>) to disengage. To shift the knob body (<NUM>) from the locked position to the unlocked position, the knob body (<NUM>) must be pulled when the protrusion (<NUM>) comes out of the recess (<NUM>).

As mentioned above, the guiding portion (<NUM>) has the pushing end (<NUM>) facing the pushing hole (<NUM>) at the shaft (<NUM>) when the knob body (<NUM>) is at the locked position. When the knob body (<NUM>) is at the locked position, the user can apply force onto the pushing end (<NUM>) through the pushing hole (<NUM>). When the pushing end (<NUM>) is pushed by the user, the guiding portion (<NUM>) stretches downward. Thus, the protrusion (<NUM>) provided on the guiding portion (<NUM>) comes out of the recess (<NUM>).

Referring to <FIG>, the cooking appliance (<NUM>) comprises a gas tap (<NUM>) which is connected to the shaft (<NUM>). The gas tap (<NUM>) having a flow control member controlled by the shaft (<NUM>) which is rotated by said control knob (<NUM>).

According to the present invention, the knob collar (<NUM>) is removably mounted on the shaft (<NUM>) and placed between the control panel (<NUM>) and the knob body (<NUM>). The knob collar (<NUM>) has a hollow shape with a bottom wall having a connection hole (<NUM>) in which the shaft (<NUM>) extends. Said connection hole (<NUM>) is formed on a raised portion at the bottom wall of the knob collar (<NUM>). An inner face of the knob collar (<NUM>) is provided with a slot (<NUM>) in which the knob body (<NUM>) is partly positioned inside. The inner face of the knob collar (<NUM>) faces the knob body (<NUM>) when the knob body (<NUM>) and knob collar (<NUM>) is connected. At least one portion of the knob body (<NUM>) can be snap-fitted into the slot (<NUM>) of the knob collar (<NUM>). Thanks to the snap-fit connection, the knob body (<NUM>) is removably mounted to the knob collar (<NUM>). Moreover, the knob collar (<NUM>) can be slidably movable on the shaft (<NUM>) between a first position in which it hides the pushing hole (<NUM>) and a second position in which it allows access to the pushing hole (<NUM>). In <FIG>, the knob collar (<NUM>) is at the first position. In order to shift the knob collar (<NUM>) from the first position to the second position, the knob collar (<NUM>) is pulled by the user. In <FIG>, the knob collar (<NUM>) is at the second position.

As seen in <FIG>, the knob body (<NUM>) has at least two slits (<NUM>) that partly extend along the guiding portion (<NUM>). The slits (<NUM>) are formed on both lateral sides of the pushing end (<NUM>). Said slits (<NUM>) make the pushing end (<NUM>) flexible and allow to be pushed for disengagement.

The cooking appliance (<NUM>) further comprises a resilience member (<NUM>) which is disposed between the knob body (<NUM>) and the knob collar (<NUM>) so that the knob body (<NUM>) is movable relative to the knob collar (<NUM>) by manipulating against the force of the resilience member (<NUM>). An end of the resilience member (<NUM>) is guided on the bottom wall of the knob collar (<NUM>) and in the proximity of the raised portion of the knob collar (<NUM>) which helps to keep the resilience member (<NUM>) in its position. The other end of the resilience member (<NUM>) is guided on a bottom wall of the knob body (<NUM>).

According to the present invention, the recess (<NUM>) has a polygonal cross-section, preferably rectangular. Since the recess (<NUM>) is shaped and dimensioned with respect to the protrusion (<NUM>), the cross-section of the recess (<NUM>) can vary. The protrusion (<NUM>) has at least a partly inclined portion (<NUM>) which is inclined with respect to the longitudinal axis of the knob body (X). This inclined portion (<NUM>) allows the engagement of the recess (<NUM>) and protrusion (<NUM>) when the knob body (<NUM>) is moved relative to the cooking appliance (<NUM>).

The cooking comprises an indicator (<NUM>) in the form of a lengthwise recess which is provided on the knob body (<NUM>). The indicator (<NUM>) is formed on the outer face of the knob body (<NUM>) and helps the user to indicate the position of the control knob (<NUM>).

A method of mounting a control knob (<NUM>) on a shaft (<NUM>) of a cooking appliance (<NUM>) comprising the steps of; providing the cooking appliance (<NUM>) wherein the cooking appliance (<NUM>) comprises a main body (<NUM>); a control panel (<NUM>) provided on the main body (<NUM>), and a switch (<NUM>) having a shaft (<NUM>) extending through the control panel (<NUM>) for adjusting a power level of a heat source, creating a recess (<NUM>) on the shaft (<NUM>) of the switch (<NUM>), providing a control knob (<NUM>) wherein the control knob (<NUM>) has a guiding portion (<NUM>) in which the shaft (<NUM>) is arranged to extend, and the guiding portion (<NUM>) having at least one protrusion (<NUM>) shaped and dimensioned with respect to the recess (<NUM>) on the shaft (<NUM>), mounting the control knob (<NUM>) to the shaft (<NUM>) such that the protrusion (<NUM>) and the recess (<NUM>) engage each other at a locked position in which the control knob (<NUM>) and the shaft (<NUM>) rotate together. The control knob (<NUM>) comprises a knob body (<NUM>) which is connected to the shaft (<NUM>). The protrusion (<NUM>) provided on the knob body (<NUM>), has at least partly inclined portion (<NUM>) which is inclined with respect to the longitudinal axis of the knob body (X). The recess (<NUM>) formed on the shaft (<NUM>) has a rectangular cross-section. When the protrusion (<NUM>) and the recess (<NUM>) are engaged to each other, the knob body (<NUM>) is connected to the shaft (<NUM>).

The method of mounting a control knob (<NUM>) on a shaft (<NUM>) of a cooking appliance (<NUM>) comprising further the step of; creating at least one pushing hole (<NUM>) on the shaft (<NUM>) as a through-hole which enables the guiding portion (<NUM>) is accessed when the knob body (<NUM>) is at the locked position and providing a pushing end (<NUM>) on the guiding portion (<NUM>) facing the pushing hole (<NUM>) at the shaft (<NUM>) when the knob body (<NUM>) is at the locked position. The pushing hole (<NUM>) enables the user can push the pushing end (<NUM>) when the knob body (<NUM>) is at the locked position. Thus, the demounting is simplified. The pushing hole (<NUM>) can be hidden by knob collar (<NUM>) which is slidably mounted on the shaft (<NUM>). The knob collar (<NUM>) is movable between the first position in which it hides the pushing hole (<NUM>) and the second position in which it allows access to the pushing hole (<NUM>).

Claim 1:
A cooking appliance (<NUM>) comprising:
a main body (<NUM>);
a control panel (<NUM>) provided on the main body (<NUM>);
a switch (<NUM>) for adjusting a power level of a heat source, the switch (<NUM>) comprising a shaft (<NUM>) extending through the control panel (<NUM>) and a control knob (<NUM>) connected to the shaft (<NUM>) for rotating the shaft (<NUM>),
wherein
said control knob (<NUM>) comprising a knob body (<NUM>) having a guiding portion (<NUM>) in which the shaft (<NUM>) is arranged to extend,
the guiding portion (<NUM>) is provided with at least one protrusion (<NUM>);
the shaft (<NUM>) is provided with at least one corresponding recess (<NUM>); and
both of the protrusion (<NUM>) and the recess (<NUM>) are being sized and shaped to engage each other at a locked position so that the knob body (<NUM>) is prevented from moving slidably on the shaft (<NUM>), characterized in that
the shaft (<NUM>) is provided with at least one pushing hole (<NUM>) as a through-hole which enables the guiding portion (<NUM>) is accessed when the knob body (<NUM>) is at the locked position, and
the guiding portion (<NUM>) has a pushing end (<NUM>) facing the pushing hole (<NUM>) at the shaft (<NUM>) when the knob body (<NUM>) is at the locked position.