A thermally actuate switching device with a rotatable combination component

Abstract: A thermally actuated switching device (1), comprising a base body (2), a electric switch (10), means (3) for actuating the switch (10) as a function of a heat responsive device (6) adjustment means including an adjustment pin (9) for adjusting the switching threshold of the switching device (1), and a combination component (15) which is coupled to and rotates with the adjustment pin (9), and integrates a friction element (20,21,22,23) which under prestress interacts with the base body (2), in order to create a frictional resistance to the rotation, a clicking element (24) which engages with a rigid part (37) on the base body (2), and a rotational movement-limiting element (17), being all the parts (15,20-23,24,37) made of metal sheet.

Description: The present invention relates to a thermally actuated switching device, comprising a base body, an electrical switch, means for actuating the switch as a function of a heat responsive device, and means for adjustment the switching threshold of the switch, according to the preamble of claim 1. In EP-A-0 377 169 the means for adjustment comprises a setting spindle interacting, via the diaphragm, with an actuating arm for the switch operation. US-3,943,479 discloses a switching device with a setting spindle provided with a drive plate secured to the spindle for rotation herewith, and a unrotatable disk-like spring to provide the frictional resistance to the rotation of the spindle. The indication of the rotational position of the spindle is effected through a separated cam engaging with the drive plate. US-4,274,546, discloses a switching device with an adjustment screw which is provided with a rotatable cradle-like or "U"-shaped member, for the only purpose of centering the diaphragm relative to the spindle axis. The cradle-like member has a pair of upwardly directed arms, each provided with an outwardly turned end, the later provided with a rounded embossment, serving only to the purpose of centering the cradle-like member relative to the actuating lever arm. US-4,214,224 discloses a switching device in accordance with the preamble of claim 1, whose setting spindle is provided with a fixed annular member, made of resilient material with provides only a second rotation stop tab to the stop lug element fitted onto the setting spindle. A first stop tab is provided by the cover of the switching device. The combination of the stop lug element and the annular member only serves to the purpose of the angular displacement between two end positions. No frictional resistance is provided by such combination of elements. The switching devices according to the prior art comprise a large number of separate component which are coupled to a base body. The base body is made from a non-resilient material. In order to create a frictional resistance to rotation thereon, the friction means comprise the adjustment pin or a rigid component coupled thereto, which interacts with another resilient component coupled to the base body. This means that a separated resilient component is always need coupled to the base body. Also, in many cases it is necessary for there to have a means which indicates one or more defined positions of the adjustment pin, by a perceptible click, as a manner to feel a zero-position or a lowest and a highest positions without needing to make a visual check. Likewise, in the prior art the clicking action is obtained by allowing a resilient component on the base body to interact with one rigid component on the adjustment pin. Therefore, for this purpose, at least two components are necessary and have to be attached separately. The object of the invention is a thermally actuated switching device with a combination component as is defined in claim 1. The switching device according to the invention provides a friction element, which is itself resilient, and interacts with part of the base body itself, thus allowing one component to be dispensed with. The switching device comprises a calibration nut fixed to the base body, which guides the advance of the rotatable adjustment pin or setting spindle of the switch. A rotational friction of said element belonging to the combination component against the fixed nut is created, to cause a necessary force couple for rotating the adjustment pin. The adjustment pin is provided with a co-rotating clicking component with a resilient projection, which is able to interact with one substantially rigid component on the base body in order to indicate the predefined positions of the adjustment pin, as limits of the rotation range. The friction element and the clicking element are designed as a combination component. The number of components required is thus reduced. Advantageously, the combination component furthermore comprises a rotational movement-limiting projection integral with the combination component. In this way, three functions are performed by only one combination component, which reduces the number of components with respect to the prior art still further. The switching device according to the invention is thus assembled more quickly than devices of prior art. The combination component coupled to the adjustment pin, is able to rotate therewith. In practice, being the adjustment pin a threaded spindle, which moves axially during the rotation of the pin, the component coupled to the pin must not be able to be displaced together with the pin, which could have an adverse effect on the operation of the components. This displacement is avoided by making the combination component to be held rather stationary with respect to the base body, by means of an integral stop means of the latter, but being slightly slidable under prestressing when it engages the base body. Fig. 1 shows a cross-sectional view of a thermally actuated switching device, according to the invention; Fig. 2 shows a perspective partial view the switching device of the fig. 1; Fig. 3 shows a perspective view of the combination component of the fig. 2. With reference to the fig. 1, the setting spindle 9 is the adjustment pin which interacts by axial displacement via the diaphragm 6, with the actuating arm 3 to switching the electric contact 10. The setting spindle 9 is provided with a longitudinal portion 9a threaded in a nut 41. The nut 41 which is provided on the outside with a collar 33, is a riveted nut which is fastened in a bore in a base wall 25 of the base body 2, and is also used to calibrate the switching device, by rotating the nut 4 with respect to the base body with the aid of a special tool. The actuating arm 3 is supported in a back wall 28 of the base body. The combination component 15, shown in figures 2 and 3, comprises a disc-like portion 16 provided with a movement-limiting projection 17, situated in the plane of the disc-like portion 16. Furthermore, the combination component 15 comprises a central opening 18 for fastening the combination component to the adjustment pin 9, the opening 18 has two bent lips 19, which serve to allow the adjustment pin 9 to advance without being accompanied by the combination component 15, and having the adjustment pin 9 therefor a semi-circular cross section 9b. Two raised wings 20 and 21, each with a cutout 22 and 23 respectively, are connected to the disc-like portion 16, and close to its free end, the wing 21 comprises a clicking tongue 24 which extends substantially transversely thereto. Although the description and figures are referred to a combination component 15 integrating the three functions, the adjustment pin 9 may couple a separated angular movement-limiting element. For mounting into the switching device, the combination component 15 is slid onto the adjustment pin 9, and is clamped onto the riveted nut 41, by fitting the collar 33 of the later in a snap-in manner into the cutouts 22 and 23, which form the stop which serves to hold the combination component 15 substantially stationary as the adjustment pin 9 advances with respect to the base body 2, in other words to keep it substantially in position with respect to the base body 2. A part 37 is cut out of the base wall 25 of the base body and bent upwards, which part 37 has a stop 38, which is able to interact with the movement-limiting projection 17 on the combination component 15, and a tab 39, which is able to interact with the clicking tongue 24 of the combination component. During rotation of the combination component 15, the clamping interaction between the wings 20 and 21 and the nut 41 creates resistance to rotation of the adjustment pin 9. Due to the play between the cutouts 22 and 23 and the collar 33 in the said snap connection, a slightly sliding of the combination component 15 along the adjustment pin 9 is possible under prestress, in order to be kept in position with the base body 2, when the clicking tongue 24 engages the tab 39 projecting from the base body (2).

Claims: A thermally actuated switching device (1), comprising a base body (2), an electric switch (10), means (3) for actuating the switch (10) as a function of a heat responsive device (6), an adjustment pin (9) for adjusting the switching temperature, means (16,20,21,22) disk-like shaped made of sheet metal and coupled to the adjustment pin (9), and being rotatable therewith for creating a frictional resistance to rotation of the adjustment pin (9), means (24,37) for indicating at least one predefined angular position of the adjustment pin (9) relative to the temperature range, and means (17,38) for limiting the rotational movement of the adjustment pin (9), characterized in that a calibration nut (41) is held in the base body (2) for guiding the advance of the adjustment pin (9), and said friction means (16,20,21,22) and said indicating means (24,37) are integrated in a combination component (15) which is clamped onto the calibration nut (41) and connected thereto, being able to be slightly slid under prestress, in order to be kept in position with respect to the base body (2). The switching device according to claim 1, characterized in that the combination component (15) is provided with a clicking indication tongue (24) which engages with one rigid part (37) integral with the base body (2), and with a projection (17) which interacts with one stop (38) of rigid part (37) on the base body (2) in order to limit the rotational movement. The switching device according to claim 1, characterized in that the combination component (15) comprises a disc-like portion (16) with a central aperture (18) for fastening on the adjustment pin (9), two raised wings (20,21) with cutouts (22,23) which are connected in a snap-in manner with a collar (33) on the calibration nut (41), as stop means (22,23,33) for the axial displacement of the combination component (15).

Inventors: AZPEITIA DE DIEGO RAMON, AZPEITIA DE DIEGO, RAMON
Applicants: FAGOR S COOP, FAGOR, S.COOP
Application year: 1998
Main classification: H01H35
IPC codes: H01H35