Electricity: electrothermally or thermally actuated switches – Thermally actuated switches – With longitudinally expansible solid element
Reexamination Certificate
1999-10-12
2001-10-16
Tolin, Gerald (Department: 2835)
Electricity: electrothermally or thermally actuated switches
Thermally actuated switches
With longitudinally expansible solid element
C337S393000, C337S398000, C337S123000
Reexamination Certificate
active
06304165
ABSTRACT:
FIELD OF APPLICATION AND PRIOR ART
The invention relates to a switching device for an electric heating device with a substantially rod-shaped temperature sensor, which comprises a tube and a longitudinal element located therein, the tube and the longitudinal element having different thermal expansion coefficients, and with at least one switch located in a base and operated by the temperature sensor and which is provided with a switch spring, particularly a catch spring, the temperature sensor tripping the switch by means of an actuator separate from the switch spring, the actuator having at least one actuating part, which is loaded by a spring element in or counter to the actuating direction.
A switching device of the aforementioned type is e.g. known from DE-OS 28 39 161. The latter has as an actuator a unilaterally mounted lever through which is guided a rod-like longitudinal element. Fixing takes place by means of a helical spring supported on the base and which presses the lever against a nut guided by means of a screw thread at the end of the rod. The nut running on the rod screw thread serves as an adjusting device. In the lever are inserted two actuating pins, which in each case point in opposite directions and operate two switches.
PROBLEM AND SOLUTION
The problem of the invention is to provide such a switching device, which obviates the disadvantages of the prior art and in particular reduces assembly costs and permits reliable operation.
This problem is solved by the features of claim
1
. Advantageous developments of the invention form the subject matter of the subclaims.
An inventive, one-part construction of the at least one actuating part with the spring element in particular facilitates assembly, but other advantages can also result therefrom. As a result of the one-part nature it is possible to save at least one fixing or mounting means, particularly for at least one actuating part. A fixed association or connection between the actuating part and the spring element increases the mechanical reliability of the switching device, because a disadjustment is avoided.
An actuator can be supported in leaf spring-like manner on the base, particularly with both end regions for increasing the spring action. The longitudinal element can act on the actuator, which preferably has at least one actuating part for bearing on the switch.
Preferably the spring element and the at least one actuating part and/or the actuator are rough-worked from a single material piece. A particularly simple construction can be rough-worked from a flat material and correspondingly shaped by bending. Another possibility is e.g. a fixed connection by bonding or welding and optionally also by extrusion. This in particular covers a one-part configuration allowing the objects in the fitted state to act as a single part, in which the individual parts have in at least one other direction than the assembly direction a positive engagement.
The spring element is preferably constructed as a compression spring in order to ensure precise working. The spring element is preferably leaf spring-like. A leaf spring is advantageously mounted with both end regions or ends in the base, particularly by engagement on engagement areas brought about by spring tension. A leaf spring advantageously runs substantially at right angles to the extension direction of the temperature sensor, so that it is possible to avoid undesired shear forces or the like.
In a particularly preferred manner the temperature sensor engages or bears roughly centrally on the leaf spring, so that there is a uniform loading thereof. The actuating part advantageously runs in the vicinity of the temperature sensor and is in particular positioned roughly centrally on the leaf spring.
The actuating part advantageously has two legs projecting from the spring element for bearing on the switch and it is in particular roughly U-shaped. The U-shaped legs are preferably twisted by approximately 90° to the longitudinal extension of the leaf spring. The legs can in each case be led to different switches, but preferably engage on the same switch. The temperature sensors can directly point into or run into the U-shape.
Preferably a mechanical connection between the temperature sensor and the actuator is an adjustable transfer means, particularly an adjusting device. The adjusting device advantageously engages on the temperature sensor, particularly on the end thereof. The adjusting device preferably engages on the longitudinal element, which can project over the tube.
A preferred bearing possibility for the adjusting device is on the actuator and is in particular fixed thereto. In one construction possibility it can engage on or be received in the centre of a U-shaped actuating part. As another advantageous possibility the spring element has a receptacle for the adjusting device, particularly in the case of a one-piece construction of spring element and actuating part.
A receptacle for the adjusting device can be a thread for an adjusting screw, which preferably runs in the direction of the longitudinal element and/or in the actuating direction of the switch. The adjustment precision can be varied by modifying the pitch of the adjusting screw.
The transfer of the actuating force can be through the switch and/or switch spring, particularly through a corresponding opening, which for stability reasons should not be open to the rim. As a function of the assembly type the longitudinal element can pass through one side or the adjusting device or screw on the other.
Advantageously the longitudinal element is at least partly constructed as a rod and is in particular completely in the form of a rod. It is possible in the case of a temperature sensor, which covers differently heatable heating areas of a heating device, to associate with in each case one heating area a rod area or a separate rod with characteristics adapted thereto. The rods are then successively placed in the tube, so that their individual extensions can be summated to an overall extension. However, in particularly preferred manner the longitudinal element is constructed as a one-piece rod. Advantageously the longitudinal element has a lower expansion coefficient than the tube and e.g. ceramic or glass can be used as its material.
According to an embodiment the at least one actuating part can substantially embrace the rod and preferably engages externally in the end region thereof. It advantageously forms a guide for the rod, particularly for securing the rod against undesired movement transversely to the actuating direction. A positive connection between the actuating part in a plane at right angles to the actuating direction can prevent an undesired, mutual shifting of the parts. A guide can be constructed as an inward curvature of the at least one actuating part towards the rod. The inward curvature is preferably provided with a recess corresponding to the external diameter of the rod in or along which runs said rod. Guidance by an adjusting screw can be in the form of a tubular portion engaging over the rod, e.g. in the form of a bore in the end face of the adjusting screw.
An overpressure preventer for the switch can be implemented by the actuating part having a certain elasticity in the actuating direction. This can be obtained by at least one S-shaped or Z-shaped bend, preferably as an inward curvature in the form of a spring bend or elbow, which can be combined with the above-described guide.
Preferably the leaf spring in the base is mounted in a reception chamber, which has in particular bearing areas for the leaf spring pointing counter to the actuating direction. The reception chamber can widen in the leaf spring bending direction as from the bearing areas. The leaf spring preferably engages on through base walls, which serve as bearing areas and limit widening. Preferably the widening is roughly symmetrical, particularly symmetrical to a plane running along the actuating direction. A mobility of the leaf spring in the reception chamber can be obtained in that at the point of maximum width the r
Mannuss Siegfried
Petri Heinz
Wilde Eugen
E.G.O. Elektro-Geratebau GmbH
Senterfitt Akerman
Tolin Gerald
Vortman Anatoly
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