Ignition switch assembly for a gas tap

TECHNICAL FIELD

The present invention is related to ignition switch assemblies for gas tap suitable for a cooking appliance.

PRIOR ART

Gas taps suitable for a cooking appliance are known comprising a tap body with a conical internal housing suitable for receiving a conical rotational member for regulating gas flow, a manually operated rotary shaft coupled to the conical regulating member, and an ignition switch assembly that is operated when the user turns the rotary shaft in any of the directions of rotation, causing ignition of the flame at least when turning in one of the directions of rotation.

Safety rules for operating gas taps require that to open the gas flow passage, at least two maneuvers must be performed first, such as pushing on the rotary shaft and subsequently turning it, driving the conical regulating member until opening the gas flow.

US2010035195 A1 describes a gas tap with an ignition switch assembly suitable for a cooking appliance, comprising a rotary shaft, an ignition switch assembly coupled to the rotary shaft, said ignition switch assembly including a fixed contact means and a movable contact means, a coupling element through which the ignition switch assembly is coupled to the rotary shaft, said coupling element being rotational and integral with the rotary shaft in a rotational movement, and a cam coupled to the rotary shaft through the coupling element, shifting the movable contact means towards the fixed contact means, electrical contact being produced when the coupling element is turned.

US5525771A and US4371764A disclose an ignition switch assembly for a gas tap according to the preamble of claim1.

DISCLOSURE OF THE INVENTION

The object of the invention is to provide an ignition switch assembly for a gas tap of a cooking appliance, as defined in the claims.

The ignition switch assembly of the invention comprises a rotary shaft, a fixed contact means and a movable contact means, a coupling element coupled to the rotary shaft, said coupling element being rotational and integral with the rotary shaft in a rotational movement, and a cam coupled to the coupling element, shifting the movable contact means towards the fixed contact means, electrical contact being produced when the coupling element is turned.

The ignition switch assembly of the invention comprises at least one resistance means other than the cam shifting the movable contact means of the ignition switch assembly, in the rotational movement of the rotary shaft. This resistance means resists against the movement of the rotary shaft, making the force that a user must exert to turn said rotary shaft greater, and is different from the resistance put forth by the cam against the rotational movement when contacting with the movable contact means.

The coupling element and the rotary shaft can turn an angle of rotation in either of the two directions, from an initial position corresponding to the closed OFF position of the gas flow, to a final position corresponding to a specific gas flow. The coupling element has a substantially cylindrical shape, with a substantially planar outer side surface and a substantially planar inner side surface, at least one of said side surfaces cooperating with the resistance means in at least one section of the angle of rotation, the cam being part of the coupling element, being integral with said element since the cam is arranged on the outer side surface, taking up the width of said side surface and being raised high enough so that it can contact with the movable contact means when turning the coupling element.

The contact of the cam is on a movable means, and therefore said contact is gentle and is not designed to resist against the rotational movement. A safety measure against accidental movements of the rotary shaft is added with this resistance means, to the measures required by the safety rules. These accidental movements that can be caused by the user can include the user unintentionally supporting against or turning the shaft of the taps, or in the case of children, movements caused while playing. By providing the resistance means said accidental movements are hindered.

These and other advantages and features of the invention will become evident in view of the drawings and the detailed description of the invention.

DESCRIPTION OF THE DRAWINGS

• Figure 1 shows a perspective view of an ignition switch assembly connected to a rotary shaft of a gas tap according to the invention.
• Figure 2 shows a front view of an embodiment of an ignition switch assembly, without a cover and with resistance means in the form of a sheet.
• Figure 3 shows a front view of a second embodiment of an ignition switch assembly, without a cover and with resistance means in the form of a sheet with a protuberance.
• Figure 4 shows a perspective view of a third embodiment of an ignition switch assembly, without a cover and with resistance means in the form of an assembly formed by a ball and a spring.
• Figure 5 shows a longitudinal section view of a fourth embodiment of an ignition switch assembly, with resistance means in the form of a gasket.
• Figure 6 shows a perspective view of an embodiment of the coupling element of the ignition switch assembly.

DETAILED DISCLOSURE OF THE INVENTION

Figure 1 shows a perspective view of an ignition switch assembly 3 connected to a rotary shaft 2 of a gas tap 1 according to the invention. In this embodiment, the ignition switch assembly externally comprises a container comprising a fixed casing 6 where the different elements internally comprised in the ignition switch assembly 3 are located, and a movable cover 19 which is removable. The ignition switch assembly is mounted on the rotary shaft 2 of the gas tap 1, and the casing 6 is supported on a cover 54 of the gas tap 1, although it can also be mounted on the tap body 50.

Figure 2 shows an embodiment of an ignition switch assembly 3 according to the invention, with the cover 19 removed. This ignition switch assembly 3 has the function of a switch of a spark generator firing a spark plug (not shown in the drawings). The ignition switch assembly 3 comprises a fixed contact means 20 and a movable contact means 25, a coupling element 5 comprising a central hole shaped such that it is integral with the rotary shaft 2 in a rotational movement and allows the axial movement of said shaft 2. The coupling element 5 is coupled to the ignition switch assembly 3 such that it allows the rotational movement thereof together with the rotary shaft 2. The ignition switch assembly 3 also comprises a cam 30 that is coupled to the coupling element 5, the function of the cam 30 when the rotary shaft 2 is turned being to shift the movable contact means 25 towards the fixed contact means 20, achieving contact between both movable means 25 and fixed means 20, and electrical contact being produced when the rotary shaft 2 is turned.

When contact between the movable contact means 25 and the fixed contact means 20 is made by means of the cam 30, resistance against the turning of the rotary shaft 2 is produced, though it is very gentle. Though it complies with the regulatory requirement of at least two maneuvers for being able to open the gas tap, the user does not perceive it as a deterrent force in the event of possible accidents. If greater resistance against said rotational movement, and thus accident prevention, is desired, it is necessary to arrange added resistance means. For this purpose, the ignition switch assembly 3 comprises at least one resistance means 4, other than the cam 30, that resists against the rotational movement of the rotary shaft 2.

The resistance means 4 is arranged inside the ignition switch assembly 3, the ignition switch assembly 3 comprising a casing 6 fixed to the outside of the gas tap 1 on the cover 54 by means of supports projecting from the rear portion of the casing 6. The ignition switch assembly 3 can also be supported on the gas tap 1 by means of the tap body. The resistance means 4 is located inside the casing 6 supported such that it can be considered to be anchored in said casing 6.

The rotary shaft 2 and the coupling element 5 can rotate an angle A in either of the two directions, usually greater than 160°, for the gas flow G supply. The angle of rotation A is from an initial position 60 of rotation, corresponding to the closed OFF position of the gas flow supply, to a final position 61 corresponding to a minimum gas flow, passing through an intermediate position 62 for maximum gas flow supply, as shown in Figure 2.

The resistance means 4 is in contact with the coupling element 5 in at least one section of the angle of rotation A, resisting against the rotational movement of the rotary shaft 2. Figure 6 shows a perspective view of an embodiment of the coupling element 5 of the ignition switch assembly 3, wherein said coupling element 5 is a body having a substantially cylindrical shape, with a central hole that allows the coupling thereof to the rotary shaft 2. In its side central area it comprises an outer side surface 7 which is substantially planar, and at its lower end it comprises a wing-shaped edge, the edge and the side surface 7 allowing the fitting of the coupling element 5 in the supports of the casing 6, such that said element 5 can turn in the supports of the casing 6. The coupling element 5 comprises an also substantially planar inner side surface 8.

The embodiment of Figure 2 shows a front view of the ignition switch assembly 3, in which the front cover 19 of the ignition switch assembly 3 has been removed, showing the inside of the casing 6. The resistance means 4, which is located inside the casing 6, is a thin planar sheet in this embodiment with a width equal to or less than that of the side surface 7 of the coupling element 5. The sheet 4 is attached at its two ends 9, 10 to two respective supports 11, 12 of the casing 6 of the ignition switch assembly 3, this attachment being performed in the embodiment shown with slots in the supports 11, 12 that allow removing the sheet 4 for its possible replacement. This fixing of the sheet 4 is located such that the sheet 4 is constantly in contact with the coupling element 5 on its side surface 7. The material of the sheet 4 is a high friction material, at least on the upper surface contacting with the coupling element 5. This material can be rubber, for example, or the contact surface of the sheet 4 can also be rough. Therefore, when the rotary shaft 2 is turned, the coupling element 5 turns integrally therewith, and when the side surface 7 slides over the sheet 4, it produces a friction force in this sheet 4 that resists against the rotational movement of the rotary shaft 2, generating a torque hindering said movement. This resistance against the rotational movement is produced throughout the entire angle of rotation A, and in the direction for both opening and for closing the gas tap 1.

Figure 3 shows a second embodiment of the ignition switch assembly 3 of the invention with a resistance means 4 in the form of a sheet with a protuberance 13. Said embodiment shows a front view of the ignition switch assembly 3, in which the front cover 19 of the ignition switch assembly 3 has been removed, showing the inside of the casing 6. The ignition switch assembly 3 comprises the elements described in the embodiment shown in Figure 2, with the difference being the resistance means 4. In this embodiment, the resistance means 4 is also a thin planar sheet, comprising a semi-cylindrical shaped protuberance 13 arranged substantially in the center of the sheet 4 in this second embodiment, and the length of which coincides substantially with the width of the sheet 4 and the width of the side surface 7 of the coupling element 5. The coupling element 5 comprises on its side surface 7 a semi-cylindrical shaped housing 14, having about the same dimensions as the protuberance 13, such that the protuberance 13 is arranged in the housing 14 when the rotary shaft 2 is located in the initial closed OFF position 60 of the gas flow. When the user opens the gas tap 1, he/she turns the rotary shaft 2, encountering considerable resistance due to housing the protuberance 13 of the sheet 4 in the housing 14. The user has to exert a force that allows removing the protuberance 13 from said housing 14, and when continuing with turning, and preferably from the intermediate position 62 corresponding to maximum flow, said protuberance 13 continues contacting with the side surface 7, producing a friction force in the protuberance 13 that resists against the rotational movement of the rotary shaft 2. This initial resistance against the rotational movement while the protuberance 13 comes out of the housing 14, and the continued resistance while the shaft 2 is turned, are produced during the entire angle of rotation A, and in the direction for both opening and for closing of the rotary shaft 2. The support of the sheet 4 in the casing 6 of the ignition switch assembly 3 is similar to that shown in the embodiment of Figure 2, the ends 9, 10 of the sheet being supported in slots of the supports 11, 12 of the casing 6, allowing the removal thereof. Likewise, the material of the sheet 4 and its finish has the same technical features as those described above for the embodiment of Figure 2, thus fulfilling the same functions defined for said embodiment.

Figure 4 shows a third embodiment of the ignition switch assembly 3 of the invention with a resistance means 4 in the form of an assembly formed by a ball 15 and a spring 16. Said embodiment shows a perspective view of the ignition switch assembly 3, in which the front cover 19 of the ignition switch assembly 3 has been removed, showing the inside of the casing 6. The ignition switch assembly 3 comprises the elements described in the embodiments shown in Figures 2 and 3, with the difference being the resistance means 4 and the means required for housing same in the casing 6. In this embodiment, the resistance means 4 is an assembly formed by a ball 15 supported in a spring 16 arranged in a substantially vertical position in this embodiment. The spring 16 is arranged in a housing 17 of the casing 6 allowing its axial shift. The housing 17 is a groove formed partially in the portion of the casing 6 where the coupling element 5 and the supports allowing its turning are arranged, and the portion of the groove 17 that is missing is arranged in the cover of the casing 6 (not shown in the drawing), such that when the casing 6 is closed with the cover, the groove 17 is completed. The coupling element 5 comprises on its side surface 7 a semi-spherical shaped housing 18, having about the same dimensions as the ball 15, such that the ball 15 is arranged in the housing 18 due to the force exerted by the spring 16 when the rotary shaft 2 is located in the initial closed OFF position 60 of the gas flow. In this embodiment, the angle of rotation A of the rotary shaft 2 is substantially the same as that shown in the embodiment of Figure 2, with the same defined initial position 60, final position 61 and intermediate position 62. When the user opens the gas tap 1 and turns the rotary shaft 2, he/she encounters considerable resistance due to housing the ball 15 of the assembly of the resistance means 4 in the housing 18. The user has to exert a force that allows removing the ball 15 from said housing 18, and when continuing with turning, and preferably from the intermediate position 62 corresponding to maximum flow, said ball 15 continues contacting with the side surface 7, producing a friction force in the ball 15 that resists against the rotational movement of the rotary shaft 2. This initial resistance against the rotational movement while the ball 15 comes out of the housing 18, and the continued resistance while the shaft 2 is turned, are produced during the entire angle of rotation A, and in the direction for both opening and for closing of the rotary shaft 2. In this embodiment, contact between the ball 15 and the side surface 7 is produced at one point, so the produced friction force is less than the friction force resulting in the embodiment shown in Figure 3. When the gas tap 1 is closed by arranging the rotary shaft 2 in position 60, both in this embodiment and in the embodiment shown in Figure 3, the housings 18 and 14, respectively, facilitate the positioning of the ball 15 and the protuberance 13, respectively, adding a click-like sound indication. The material used to manufacture the spring 16 is the material normally used and referred to as spring steel, and the material of the ball 15 can be plastic, for example, though preferably stainless steel is used.

Figure 5 shows a fourth embodiment of the ignition switch assembly 3 of the invention with a resistance means 4 in the form of a gasket. Said embodiment shows a side sectioned view of the gas tap 1 with the ignition switch assembly 3 mounted. The ignition switch assembly 3 comprises the elements described in the embodiments shown in Figures 2, 3 and 4, with the difference being the resistance means 4 and the means required for housing same in the casing 6 and the gas tap 1. In this embodiment, the resistance means 4 is a gasket arranged inside the coupling element 5. Said gasket 4 is supported on one side against the casing 6 of the ignition switch assembly 3, in the portion of the casing 6 where the coupling element 5 and the supports allowing its turning are located. The cover 54 of the gas tap 1 comprises a tubular portion 54a surrounding and fitting with the diameter of the rotary shaft 2, guiding it in its rotation. The gasket 4 of the ignition switch assembly 3 surrounds with its inner diameter the tubular portion 54a on its outside, being fitted to it, and contacts in its outer diameter with the coupling element 5 on its inner surface 8. When the user opens the gas tap 1 and turns the rotary shaft 2 from the initial position OFF 60 to the final position 61, and in both directions of rotation, a friction force is produced in the gasket 4 that resists against the rotational movement of the rotary shaft 2. In this embodiment, the angle of rotation A of the rotary shaft 2 is substantially equal to that described in the embodiment of Figures 2, 3 and 4, with the same defined initial position 60, final position 61 and intermediate position 62. The material used to manufacture the gasket 4 is an elastomeric material having elasticity, durability and resistance properties required for this application. There is friction between the gasket 4 and the cover, as well as between the gasket 4 and the coupling element 5, and depending on the tight fit between the gasket 4 and the cover, this friction is greater than the friction existing with the coupling element 5, the gasket 4 remaining fixed and brushing against the inner side surface 8 of the coupling element 5 in the gasket 4, producing resistance against the rotational movement. According to the invention, the cam 30 is part of the coupling element 5, being integral with said element 5 since the cam 30 is arranged on the side surface 7, taking up the width of said side surface 7 and being raised high enough so that it can contact with the movable contact means 25 when turning the coupling element 5. According to the embodiment shown in Figure 2, but extensible to the embodiments shown in Figures 3, 4 and 5, the ignition switch assembly 3 comprises inside the casing 6 the fixed electrical contact means 20 which is attached at its two ends 21, 22 to two respective supports 23, 24 of the casing 6. The ignition switch assembly 3 also internally comprises the movable electrical contact means 25 attached at one end 26 to a support 28 of the casing 6, and it is simply supported at the other end 27 on a support 29 of the casing 6. Since the cam 30 is part of the coupling element 5, when the rotary shaft 2 is operated by the user and turns in the angle of rotation A in either direction, it contacts with the movable contact means 25, pushes it, and since the end 27 of the movable contact 25 is supported on the support 29 of the casing 6, it shifts and contacts with the fixed contact 20 of the ignition switch assembly 3. This contact closes an electric circuit and causes the spark generator to generate sparks in the spark plug (not shown in the drawings). In the shown embodiments, this generation of sparks produces sparks in the spark plug when the rotary shaft 2 turns in both directions, i.e., the direction for opening and for closing the gas tap 1, but it is not limiting.

In any of the embodiments shown in Figures 2 to 5, the rotary shaft 2 turns the angle of rotation A from the initial OFF position 60, located at 0°, to the final position 61 corresponding to a minimum gas flow, located between about 160° and between about 270°, the final position 61 of about 210° being shown in Figure 2. The rotation of the angle A in opening is towards the left and passes through an intermediate position 62 corresponding to a maximum gas flow, located at about 90°. When the gas tap 1 is opened, the gas is regulated, the gas flow starting to open in a position corresponding to an angle of about 30°. However, the user turns the rotary shaft 2 to the position 62 of maximum gas flow and keeps it in said position until the sparks generated by the spark plug produce the flame. Therefore, when the gas flow starts to open in the position of 30°, it is necessary for sparks to be generated, and to that end the cam 30 of the coupling element 5 contacts with the movable contact means 25 of the ignition switch assembly between an angle of about 20° and an angle of about 85°. A sufficiently large section of the angle of rotation A of 20° to 85° is thus obtained so that flame can be generated from the position of 30° in which there is already gas flow, and the user can stop pressing on the rotary shaft 2 in the position 62 of maximum gas flow due to the initiation of the opening of the gas tap 1, and can then regulate the position of the shaft 2 where needed.

Different embodiments of the ignition switch assembly 3, which can be mounted indistinctly in a gas tap 1 for a cooking appliance of the type comprising a tap body 50 with a conical internal housing suitable for receiving a conical rotational member for regulating gas flow, a manually operated rotary shaft 2 coupled to the conical regulating member, and a cover 54 covering the housing of the tap body 50, are thus obtained.