EP2287877B1 - Temperature sensor and method for adjusting same - Google Patents

Description

Field of application and state of the art

The invention relates to a temperature sensor, in particular a so-called rod controller, and a method for adjusting such a temperature sensor.

From the GB 2 175 141 A a temperature sensor is known in which two expansion elements act as a pipe and a rod on a rocker whose two ends each act in the same direction of action on two switching springs. The shift springs are adjustable with respect to their switching points by means of adjusting screws, each acting against the ends of a shift spring base of the shift springs.

From the US 4,604,603 A a temperature sensor is known with tube and rod as expansion elements, which act on a plunger, which controls or switches two series-connected switching springs. While a switching spring is not adjustable at all, an adjustment takes place in the other switching spring by a rotatable cam with varying radius, which rests against the switching spring base and adjusted their angular position.

From the EP 1 251 540 A2 is a temperature sensor with tube and rod known as expansion elements, which has two successively arranged in the effective direction of the expansion elements switching springs. A first switching spring is connected via a plunger directly to the rod or articulated by this. About a length-adjustable element that is slipped over the plunger, a switching point of the second switching spring can be adjusted.

From the EP 1 926 117 A2 is a temperature sensor with tube and rod known as expansion elements, however, has only a single switching spring. To set a switching point an adjusting screw is also provided here, which acts in a direction parallel to the longitudinal direction of the rod.

From the EP 1 569 257 A1 a temperature sensor is known, which is also referred to as a rod controller. It contains two switching springs, which are triggered by a second expansion element, which is mounted in a tubular first expansion element. Usually, the first expansion element consists of a metal tube, while the second expansion element is a ceramic rod. As a result of different coefficients of thermal expansion, only the tube expands when heated, and the rod moves relative to it out of a housing of the temperature sensor, which contains the switching springs. At each provided for each switching spring trip point these are triggered or switched, which should thus be done at two different, adjustable temperatures. The setting of these trip points or switching temperatures is of great importance and technically not very easy to solve.

Task and solution

The invention has for its object to provide a temperature sensor mentioned above and a method for its adjustment, with which problems of the prior art can be solved and in particular an aforementioned adjustment can be done constructively and well from the process.

This object is achieved by a temperature sensor with the features of claim 1 and a method for its adjustment with the features of claim 5. Advantageous and preferred embodiments of the invention are the subject of further claims and will be explained in more detail below. Some of the features listed below are only mentioned for the temperature sensor or just for the procedure. However, they should be able to apply independently to both the temperature sensor and the method. The wording of the claims is incorporated herein by express reference.

It is envisaged that the temperature sensor comprises a housing which contains two switching springs, wherein a first tubular expansion element is connected to the housing. This first expansion element includes a second expansion element, which is designed as a rod, wherein the two expansion elements have different thermal expansion coefficients and perform a relative movement to each other when heated or temperature changes. A first switching spring in the temperature sensor is biased against a position and carries a switching contact, which acts on one side of the switching spring of the rod, for which an advantageous intermediate element may be provided so that the rod does not directly touch the switching spring. In the effective direction of the rod or the elongated intermediate element in extension of the rod, a second switching spring is provided which is fixed to a second switching spring base.

According to the invention, in a first basic embodiment of the invention, the second switching spring base is designed so that it is displaceable for adjusting the switching point of the second switching spring or can be moved with at least one directional component in the longitudinal direction of the rod. The position of the second switching spring base for the insert can then be locked by locking means or by locking means be set, advantageously permanently. So the adjusted state of the switching spring is fixed.

This makes it possible that, unlike in the prior art, not the position of a switching spring or the second switching spring to its second switching spring base to which it is attached, is changed as a relative movement, but the position of the second switching spring base in the housing of the temperature sensor This improves the adjustability and the switching accuracy considerably. Above all, a locking or fixing of the second switching spring base on the housing of the temperature sensor can be carried out in a stable manner permanently, for example, by firmly welding the metallic spring base to a metallic part in the temperature sensor housing. So later changes or unwanted adjustments can be prevented.

In an embodiment of the invention, the rod is in the manner mentioned by means of said intermediate element to the first switching spring to trigger this at the trigger point or its switching point. Such an intermediate element has the advantage that it can be elongated and rod-like and thus can also represent the contact point for the second switching spring through the switching spring.

Although it is possible to integrate an adjustment for the trigger point of the first switching spring in this intermediate element or in a system of the intermediate element on the rod or on the first switching spring. This can be done for example by means of an adjustable screw thread, for example, with a running in the longitudinal direction of the rod screw or grub screw which bears against the rod or the first switching spring. By turning the screw, the trigger point can then be set exactly. However, the adjustment is advantageously carried out by a metal pin which is inserted into the still open other end of the tube and against which the rod. By moving the metal pin along the longitudinal direction of the tube then the adjustment can be made, which by its attachment to the pipe, for example by welding, can be made final. However, this is known to the person skilled in the art.

The intermediate element is advantageously made of ceramic. Thus, the rod may possibly be made of metal.

The second switch spring base is elongated and is connected in an end region of the second switch spring with this, which is removed from the end region with the switching contact. At its other end region, the second switching spring base is fixed immutable to the temperature sensor housing, in which case a certain mobility or bendability in the manner of rotation about a small angle should be possible. It is close to or provided in the region of the connection of the second switching spring base with the second switching spring an adjustable locking means for the switching spring base on the temperature sensor housing, which can be fixed either directly on the housing or on a part fixed therein in different positions. By this definition, therefore, the position of the second switching spring base and thus also the second switching spring carried thereby to the rod or a movement of the rod on the second switching spring transmitting intermediate element is set.

As a locking means projecting from the second switching spring base portion is provided in the invention, which can extend approximately at right angles to the longitudinal extent of the second switching spring base, that protrudes from this. In particular, a protruding locking arm can be provided, which is fixed to fix the final position of the second switching spring base in the housing to a metal part fixed in the housing, in particular welded. Welding here causes a permanent and no longer changeable definition.

When adjusting a temperature sensor is then set at a certain temperature at which the second switching spring to trigger or should perform their switching function, not yet set locking means of the second switching spring base of the corresponding switching point on the second switching spring. For this purpose, the position of the second switching spring base is adjusted accordingly, that the second switching spring switches here. Thereafter, the second switching spring base is then set in exactly this position, for example by the aforementioned detent or Arretierungsarm is permanently attached to the housing of the temperature sensor. He can in particular be welded to a said metal part. As an alternative to welding, permanently designed clamping connections are also possible. However, welding, especially as laser welding, is fast and sufficiently stable and durable.

For a first switching spring base can be provided that this can not be changed with respect to their position in the temperature sensor housing or can be mounted during assembly only in a single position. Here, the adjustment is advantageously carried out via the aforementioned intermediate element between the first switching spring base and the rod-like second expansion element. Alternatively, an adjustment of the trigger point of the first switching spring can also take place via a variable arrangement of the rod in the tubular first expansion element, for example by the two facing away from the housing end portions are interconnected and this connection is adjustable. For this purpose, an adjusting screw or a metal pin on which the rod rests, engage in the end of the tubular first expansion element in the longitudinal direction of the rod. By adjusting in the longitudinal direction, the adjustment of the trigger point can be done and finally adjusting screw or metal pin can be fixed, for example, clamped or welded.

In a further embodiment of the invention, the switch contact associated with a mating contact and in the other direction, ie away from the mating contact, a counter-stop may be provided. At these strikes the switching contact with open switching spring. In this case, the counter-stop can be adjusted in the direction of the mating contact to or away. In a preferred embodiment of the invention, the counter-stop can be adjusted or adjusted approximately along the direction of movement of the switching contact when opening or closing the switching spring. With the counter-stop, the switching behavior of the switching spring can be influenced, in particular with regard to a hysteresis window, ie the two switching points for both switching operations.

Advantageously, the counter-stop is variable or can be adjusted by an at least temporarily given mobility. It can be designed as a slide on a trained as a guide holder. Slide and holder can be fixed to each other after the setting of the counter-stop, preferably by bending or crimping or welding.

Alternatively, the counter-stop can be bent for adjustment and be adjusted by the deflection of its distance from the mating contact. In this case, the counter-stop can be designed so solid or stable that it is not bent by the opening and thereby striking switching spring.

In a method for adjusting an aforementioned temperature sensor according to the further embodiment is at a certain temperature at which the switching spring with the counter-stop again-βen, or to determine a desired Hysteresefensters between opening and closing the switch spring counter-stop so long in the direction the mating contact is moved until the switching spring switches again at a desired temperature or closes. Then, at this temperature, a fixation or determination of the counter-attack. This can be done advantageously as described above.

These and other features will become apparent from the claims but also from the description and the drawings, the individual features each alone or more in the form of sub-combinations in an embodiment of the invention and in other fields be realized and advantageous and protectable Represent embodiments for which protection is claimed here. The subdivision of the application into individual sections as well as intermediate headings does not restrict the general validity of the statements made thereunder.

Brief description of the drawing

An embodiment of a temperature sensor according to the invention with two switching springs is in the Fig. 1 shown schematically.

Detailed description of the embodiment

The Fig. 1 shows in a sectional plan view of a temperature sensor 11 according to the invention with an elongated sensor part, which consists in a known manner of a tube 13, usually a metal tube, and an elongated rod 14 contained therein, usually a ceramic rod. In temperature fluctuations experienced tube 13 and rod 14 different length expansions in their longitudinal direction, resulting in a relative movement in the direction of movement B. Since at the lower end of the rod 14 is pressed either with a spring force acting from above into the tube 13 or even fixed therein, for example, is clamped, there is a longitudinal movement at the upper end of the two parts. The tube 13 is fixed in a manner known per se to a housing 16 of the temperature sensor 11, wherein the housing 16 is made of an insulating material, preferably ceramic material. At the top of the tube 13, the rod 14 protrudes a piece and abuts against a known intermediate pin 18, which also consists of an insulating material, for example, ceramic or plastic.

The intermediate pin 18 has a laterally projecting pin arm 19, which acts on a first switching spring 20 of the temperature sensor 11, on its left end portion. At its other right end portion, the first switching spring 20 has a first switching contact 21, wherein the first switching spring 20 is constructed substantially as known from the prior art, see, for example, the above EP 1 569 257 A1 , The left end portion, on which the pin arm 19 acts to trigger the first switching spring 20 is connected to a first switch spring base 23, advantageously welded. This first switch spring base 23 is fixed with its right end to a metallic first holding part 25, said first holding part 25 is fixedly and immovably fixed in the housing 16. The triggering of the first switching spring 20 by a movement of the intermediate pin 18 along the direction of movement B is clear to the skilled person and need not be explained in detail here. An adjustment of the switching point, for example, by adjusting the position of the pin arm 19 or the entire intermediate member 18 relative to the triggering rod 14, which is known in the art and need not be explained here.

The upper end of the intermediate pin 18 abuts directly on a second switching spring 28, close to its right end portion, approximately between the center and the right end portion. For this purpose, the intermediate pin can pass through the first switching spring 20. Also, this second switching spring 28 with a second switch spring contact 29 provided on the left end is known from the prior art In particular, as regards their switching behavior and also their trip point or switching point.

The first switching spring 20 is usually used for interrupting a power supply of a radiant heater whose operating temperature is to monitor the temperature sensor 11. The second switching spring 28 usually switches a hot indicator, which thus indicates a residual temperature still too high for a touch on a glass-ceramic cooking surface above the radiant heater.

The right end portion of the second switching spring 28 is connected to a second switching spring base 31, advantageously welded. The second switch spring base 31 is welded to its left end portion 32 on a second holding part 35. The right-hand end portion of the second switch spring base 31 is basically free to move, or, as it were, it is movable about its left end portion 32 with a movement similar to a rotation. By this rotational mobility of the right end portion, which carries the second switching spring 28, up or down their trigger point or switching point can be adjusted or adjusted relative to the intermediate pin 18.

In Fig. 1 is further shown how, for the first switching spring 20 below the switching contact 21, a holder 37 is fixed to the housing 16. The holder 37 may be, for example, an upstanding sheet metal strip of a plate 16 secured in the housing. It is shown a slide 39 which is placed on it in the manner of a rider and at least partially overlaps it in a U-shape. The slider 39 is on the holder 37 in the direction of the switching contact 21 and the mating contact is movable or away from them. Also, the slider 39 is made of metal or sheet metal. At its upper end, the slider 39 has a counter-holder 40 in the manner of a short protruding pin, which forms the counter-stop described above. In this case, the counter-holder 40 is for example a section of the sheet metal of the slider 39 bent out. The counter-holder 40 extends in the closed state of the switching spring 20 until shortly before the free end below the switching contact 21, wherein the distance may be for example about 1 mm.

Similarly, in the second shift spring 28 above the second shift spring contact 29, a second counter-holder 42 is provided which is bent pin-like out of the end of the left end portion 32. Thus, the second counter-holder 42 is not directly displaceable or otherwise freely movable, in particular with respect to the second mating contact. For the second counter-holder 42 can be changed by different degrees of bending or bending on the mating contact to or away in its distance from the free end of the second switching spring 28 with the switch spring contact 29.

Method for adjustment and locking

With the second switching spring base 31 still movable, such an adjustment of the second switching spring fastened to it takes place by moving or rotating the second switching spring base. Thereafter, this should be determined in their position. For this purpose, it has, near the right-hand end region, a locking arm 33 which projects approximately at right angles from the second switching spring base 31. It rests against the second holding part 35 and can be fixed at a point of contact with the latter, advantageously welded, in particular by means of a laser. Then, the entire second shift spring base 31 is fixed in position and orientation, just so that the trigger point for the second shift spring 28 is adjusted to a certain desired temperature.

In this adjustment method, an adjustment of the first switching spring 20 or its triggering point is advantageous at first Provide switching point, since this is done by adjusting the position of the intermediate piece 18 to the rod 14 in the rule.

In an alternative modification of the invention that is easily recognizable to the person skilled in the art, it is possible for the end region of the second switching spring base 31, on which the second switching spring 28 itself is fastened, not to be locked when the second switching spring 28 is adjusted, but the other end region. From the Justiergenauigkeit forth, it offers but different. Furthermore, it is advantageous if the said locking arm 33 is provided as far as possible at the end of the second switching spring base 31, since then the adjustment accuracy is greatest. But this is not absolutely necessary. Constructional and structural specifications as well as good accessibility of the attachment point are also to be considered.

As previously described, the backstop 40 and the second backstop 42 can each be changed in their distance to the free end of the respective switch spring and the respective mating contact and also switch spring contact. If this distance is greater, the respective switching spring opens further. This, in turn, has an effect on the triggering point in the soon after closing of the switch again taking place closing movement by the expansion elements.

For accurate adjustment of the counter-attack, in particular the counter-holder 40, the temperature is set or generated at the expansion elements 13 and 14, in which the first switching spring 20 should close again after a previous opening. The anvil 40 is moved relatively far away from the mating contact of the switching contact 21 and then slowly back to it until just at the set temperature, the switching spring 20 switches again and closes the contact or the switch contact 21 rests against the mating contact. Then, the slider 39 is fixed to the holder 37, for example by jamming or pinching, adhesive or by welding or soldering.

Similarly, if desired, the second anvil 42 can be adjusted. Here, the adjustment is done by a more or less strong bending out or bending in the direction of the second switch spring contact 29 to or away.

Claims (5)

1. A temperature sensor, in particular for a radiant heater, the temperature sensor having a first expansion element which is connected to a housing of the temperature sensor and is in the form of a tube (13) which contains a second expansion element in the form of a rod (14), the two expansion elements having different coefficients of thermal expansion, the temperature sensor having a first switching spring (20) which is pre-stressed with respect to a point and has a switching contact (21), the rod (14) acting on one side of the switching spring (20), in particular by means of an intermediate element, a second switching spring (28) being provided in the effective direction of the rod (14) or an intermediate element as an extension of the rod, the second switching spring (28) being fastened to a second switching spring base (31), the second switching spring base (31) being movable with at least one direction component in the longitudinal direction of the rod (14) in order to adjust the switching point of the second switching spring (28), the position of the second switching spring base (31) being adapted to be locked or fixed by locking means (33), the second switching spring base (31) being elongated and connected to the second switching spring in an end region of the latter which is remote from a switching contact (29) of the second switching spring, the second switching spring base being fixed in an unalterable manner to the temperature sensor housing in its other end region, an adjustable locking means (33) being provided in the end region of the connection between the second switching spring (28) and the second switching spring base (31), which locking means can be fixed to the temperature sensor housing or to a part fixed in the latter in a different position, characterized in that
   the locking means (33) is a section which protrudes from the second switching spring base (31) and is welded to a holding part (35) fastened in the temperature sensor housing for fixing purposes.
2. The temperature sensor according to claim 1, characterized in that the rod (14) rests against the first switching spring (20) by means of an intermediate element (18, 19) in order to trigger said spring, an adjustable metal pin preferably being provided at the end of the tube in order to adjust the triggering point of the first switching spring (20), which metal pin can be moved in the longitudinal direction of the tube when it has not yet been fixed and against which pin the rod rests.
3. The temperature sensor according to claim 1 or 2, characterized in that the locking means (33) runs approximately at right angles to the longitudinal extent of the second switching spring base (31), the locking means preferably being in the form of a protruding locking arm.
4. The temperature sensor according to any of the preceding claims, characterized in that a first switching spring base (23) is fixed in its position in order to fasten the first switching spring (20) or is designed such that it cannot be adjusted with respect to the temperature sensor housing.
5. A method for adjusting a temperature sensor according to any of claims 1 to 4, characterized in that at a particular temperature at which the second switching spring (28) is intended to be triggered or is intended to switch, this switching point is set at the second switching spring while the locking means (33) of the second switching spring base (31) has not yet been fixed, wherein subsequently the second switching spring base (31) is fixed in its position by welding a locking section or locking arm of the locking means (33) to a holding part (35) in the temperature sensor housing.

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