RU2592081C1 - Heat-sensitive sensor - Google Patents

Abstract

FIELD: electronic equipment.

SUBSTANCE: invention relates to electrical engineering, namely to thermal devices for temperature control of parts and assemblies of machines, protection against thermal overload of electrical objects. Heat-sensitive sensor comprises a housing with dielectric bushing installed on one side, and with a rigidly fixed metal chamber with heat-sensitive element on the other side, spring-loaded main spring rod interacting with heat-sensitive element, and switching mechanism consisting of fixed contacts and movable contact connected with the spring-loaded rod. Housing and bushing have lengthwise guide holes, on the side of metal chamber attachment the housing has an end ledge with a hole. Rod base rests on said end ledge enclosed by the main spring. Main spring is arranged partially in the recess made on the basis of the rod and partially in the depression inside the housing. Fixed contacts are made in the form of fixed in dielectric bushing two conductors with current-carrying contact sites at the ends with a gap between them. In the said bushing hole there is a movable spring-loaded additional spring contact, which is connected with rod via trigger shaft. Trigger shaft is installed with possibility of free passage through the holes of the housing and protrusion and one end resting on the base of the rod, and the other end with insulating tip placed between the contact pads of fixed contacts to thrust against the movable contact. Housing, metal chamber, trigger shaft and the rod are made of heat-resistant alloy.

EFFECT: high reliability, efficiency of operation, ease of operation and expanded applications.

3 cl, 2 dwg

Description

The invention relates to electrical engineering, namely to thermal devices for temperature control, and can be used to control the temperature of parts and components of machines, protection against temperature overloads (overheating) of electrical objects.

There are known designs of thermal devices in which at a certain temperature the fusible substance melts and releases the rod, which, under the action of a spring, moves relative to the housing, and its position relative to the housing is an indicator of the operation of the device [US No. 3559615, cl. 116-114.5, 1971].

The disadvantage of this device is the inconvenience in operation, since it does not have an electric circuit and requires additional work when reused.

The closest to the proposed technical essence is a thermal switch containing a housing with a dielectric sleeve mounted on it on one side and a metal chamber rigidly mounted on it with a thermosensitive element, a rod spring-loaded with a main spring, interacting with a thermosensitive element, and a switching mechanism consisting of of the fixed contacts and the movable contact associated with the spring-loaded rod, the housing and the sleeve have coaxial axial holes [SU No. 725109, H01H 37/76, about pub. 03/30/1980].

The fixed contacts are fixed in a housing made of a dielectric. The thermosensitive element is placed in a metal chamber attached to the housing. The rod is positioned to move in said axial guide holes. The movable contact, made in the form of a washer, is rigidly attached to a spring-loaded stem. During melting of the thermosensitive element, the spring pushes the rod out of the melt and thereby breaks the contacts, signaling a trip.

A disadvantage of the known thermal switch is that a thermosensitive fusible substance is placed inside the device, which is why all structural elements, including electrical switches, are heated when the fusible substance is heated. Such devices that do not have remote kinematic connection with a temperature-sensitive element have to be installed directly in the zone of controlled temperature and conduct electric wires into this zone, which is impossible when controlling high temperatures. In addition, the disadvantage is low reliability due to instability of operation, which is caused by limited resistance to mechanical stress, there is the possibility of accidentally re-closing the contacts, for example, when the spring is weakened due to high temperature and the effects of vibration and shock.

The technical result, the achievement of which the claimed device is directed, is to increase the reliability and stability of operation.

The technical result is achieved by the fact that a temperature-sensitive sensor comprising a housing with a dielectric sleeve mounted on it on one side and a metal chamber with a temperature-sensitive element rigidly mounted on it, a rod spring-loaded by the main spring, interacting with the temperature-sensitive element, a switching mechanism consisting of fixed contacts and movable contact associated with the spring-loaded rod, and the housing and the sleeve have longitudinal guide holes, according to On the side of the attachment of the metal chamber, the housing has an end protrusion with a hole, and the stem is supported by the base on the specified end protrusion, which covers the main spring, partially located in a recess made on the stem base and partially in a recess in the body of the housing, fixed contacts are made in the form two conductors fixed in the dielectric sleeve with conductive contact pads at the ends with a gap between them, a movable spring-loaded additional spring is placed in the specified hole of the sleeve contact, which is connected to the rod through the transmission rod, which is installed with the possibility of free passage through the holes of the housing and the end protrusion and one end abuts against the stem base, and the other end with the insulated tip put on between the contact pads of the fixed contacts with the stop in the movable contact, and case, metal chamber, transfer rod and rod are made of heat-resistant alloy.

This constructive implementation of the rod spring-loaded with the main spring and its placement in the sensor (on the mounting side of the metal chamber the body has an end protrusion with an opening, and the stem is supported by the base on the specified end protrusion, which covers the main spring, partially located in a recess made on the base of the rod and partially - in a recess in the body of the body) gives sufficient reliability of the area of support for the rod with a significant length of its rod (which may vary depending on operating conditions) and stability of fixation of the main spring, thereby ensuring the reliability and operability of the sensor under mechanical stress (shaking, vibration, shock, etc.).

The relative position, coaxial arrangement of structural elements (movable by an additional contact spring connected to the rod through the transmission rod, installed with the possibility of free passage through the holes of the housing and the end protrusion and one end resting on the stem base) allows you to create a directional movement while moving these elements, which is positive affects the clarity of operation and the stability of the sensor under mechanical stress.

Placement of a switching mechanism with contacts in an insulated dielectric volume remote from the heat-sensitive element, namely, the implementation of fixed contacts in the form of two conductors fixed in a dielectric sleeve with conductive contact pads at the ends with a gap between them, the placement of a movable contact in the hole of the dielectric sleeve, as well as the introduction transfer rod, the second end of which with the insulated tip put on is placed between the contact pads of the fixed contacts with emphasis on the movable contact makes it possible to provide a rigid and at the same time remotely remote kinematic connection between the switching mechanism and the thermosensitive element, which ensures the reliability of the sensor and its operability at elevated temperatures.

Thus, the totality of all the above signs creates the conditions for increasing the reliability and stable operation of the temperature-sensitive sensor.

To improve performance (reduce response time), the movable contact is made in the form of a ball, the diameter of which is selected in magnitude greater than the gap between the contact pads of the fixed contacts. The shape of the movable contact facilitates its movement along the hole by reducing friction, which positively affects the performance. And the choice of the diameter of the ball in magnitude greater than the size of the gap between the contact pads of the fixed contacts allows you to minimize the path of the ball to make contact. To close the circuit, it is enough for the ball to “pointly touch” the areas of the fixed contacts.

To improve ease of use during repeated use and expand the scope, the metal chamber has a central protrusion in the form of a tube, to the end of which a thermosensitive element in the form of a cap is removably attached. In the inventive heat-sensitive sensor, the proposed constructive solution ensures that after the sensor is triggered, it is easy to replace the cap with the next one, and also makes it possible to use a cap with a different alloy from the initial heat-sensitive alloy when using the sensor in other experimental conditions, thereby expanding the scope and increasing the usability during repeated use. As a result of this, disassembly of the sensor is not required; it is enough to remove the cap and replace it with a new one. In contrast to the prototype, when reusing it is necessary to remove the metal chamber with the thermosensitive element from the installation site, melt the thermosensitive element, insert the rod into it and hold the rod until the melt solidifies, and then put the thermal switch back in place. At the same time, the design of the thermal switch according to the prototype does not allow its use in hard-to-reach places and difficult operating conditions, which narrows the scope of its application.

The presence in the claimed invention of the proposed combination of features that significantly distinguish it from the prototype allows it to be considered appropriate to the condition of "novelty."

And each of the distinguishing features of the totality clearly does not follow from the prior art (no solutions have been identified that have features that match the distinguishing features of the invention under consideration), which is evidence of the presence of an inventive step in the proposal.

The invention is illustrated by the following drawings:

in FIG. 1 - general view of the sensor in the initial state (contacts open);

in FIG. 2 - an option for installing the sensor in a layer of heat-protective material.

The temperature-sensitive sensor (Fig. 1) consists of a housing 1 with a dielectric sleeve 2 mounted on it on one side, and on the other hand a metal chamber 3 rigidly mounted on it with a temperature-sensitive element 4, a triggering mechanism, and a switching mechanism. The housing 1 and the sleeve 2 have longitudinal guide holes 5, 6, respectively. The housing 1 and the metal chamber 3 are made of heat-resistant alloy.

The chamber 3 is equipped with a central protrusion in the form of a tube 7, to the end of which a thermosensitive element 4 is attached with a thread in the form of a cap made of a thermosensitive alloy.

The actuation mechanism consists of a rod 8 and a main spring 9 interacting with the heat-sensitive element 4 of the rod. On the side of the camera 3, the housing 1 has an end protrusion 10 with an opening 11. The stem, having a T-shaped section, is supported by the base 12 on said protrusion 10, which covers the main spring 9, located partially in the recess 13 made on the base 12 and partially in the recess (annular groove) 14 in the body of the housing 1. The holes 5 and 11 are aligned.

The switching mechanism consists of fixed contacts and a movable contact. The fixed contacts are made in the form of two conductors (terminals) 15 pressed into the dielectric sleeve 2 with conductive contact pads 16 at the ends with a gap between them. The movable contact is made in the form of a conductive ball 18, spring-loaded with an additional spring 17, installed in the hole 6. The diameter of the ball 18 is selected to be larger than the gap between the contact pads 16.

The ball 18 is connected with the rod 8 through the transfer rod 19, which is installed with the possibility of free passage through the holes 5 and 11 and abuts against the base 12 at one end and placed between the contact pads 16 with the stop on the ball 18 at the other end with the insulated tip 20 on.

The entire contents of the housing 1 from the outer end is closed by an insulating cover 21 and a plate 22 made of heat-resistant alloy.

Assembly of the temperature sensor is as follows.

The rod 8 is inserted into the tube 7 of the chamber 3, and the main spring 9 is inserted into the annular groove 14. Next, the housing 1 with the chamber 3 are fastened with a thread so that the spring 9 is rested in the recess 13. Next, the insulator 23 from the press is inserted into the housing 1 -material, then a dielectric sleeve 2 with pressed in terminals 15 with conductive pads 16 at the ends with a gap between them. Through the holes 5 and 11, the rod 19 is inserted until its end stops in the base 12, and the other end of the rod 19 with the insulating tip 20 put on it is placed in the gap between the contact pads 16. Then, the ball 18 and the spring 17 are installed in the hole 6. 1 from the outer end face is closed with an insulating cover 21 and a plate 22. The sleeve 2 together with the insulator 23 and the cover 21 forms the cavity of the dielectric sleeve where the contacts are placed. The resulting assembly is additionally tightened with a retaining ring 24. Then, the cap 4, acting as a clamp, is screwed onto the end of the tube 7 until the base 12 is supported by its plane in the protrusion 10. The springs 9, 17 are in a compressed state. The sensor is ready for operation.

To install a heat-sensitive sensor in the layer 25 of heat-protective material (Fig. 2), it is necessary to make a cylindrical groove 26 to the level of critical ablation of the heat-protective material (line A, Fig. 2) taking into account the size of the cap 4, where the sensor tube 7 is introduced. The sensor has several possible mounting points. Depending on the thickness of the test layer 25, the length of the rod 8 may vary.

The device operates as follows.

In the initial state, with an allowable ambient temperature lower than the sensor response temperature, the insulating tip 20 of the rod 19 is placed in the gap between the contact pads 16 with an emphasis on the contact ball 18. The sensor contacts are open.

When the maximum ambient temperature is reached, the heat-protective layer 25 heats up, the mass is carried away from the surface of the sample, and then the thermosensitive alloy of the cap 4 softens (takes off). By the force of the main spring 9, the rod 8 is pushed through the tube 7, then it moves along the holes 5, 11, the rod 19. In this case, the spring 17 pushes the ball 18, which moves along the hole 6 to the conductive pads 16, thereby closing the electric circuit and signaling the operation of the sensor, i.e. about the critical level of ablation of heat-protective material (line A in Fig. 2).

If it is necessary to reuse the sensor, the next cap 4 of a heat-sensitive alloy is screwed onto the end of the tube 7, for which, in comparison with the prototype, there is no need to disassemble the sensor itself, which increases the ease of use. Under various conditions of application of the sensor, it is possible to use caps made of various heat-sensitive alloys, which expands the scope of application of the temperature-sensitive sensor.

Thus, the information presented indicates the fulfillment of the following set of conditions when using the claimed invention:

- a device embodying the claimed invention, when it is implemented, is intended for use in electrical engineering, namely, it relates to thermal devices for temperature control, and can be used to control the temperature of machine parts and assemblies, protection against temperature overloads (overheating) of electrical objects;

- a tool embodying the claimed invention, when implemented, is able to increase reliability, stability of response and speed, increase ease of use and expand the scope;

- for the claimed device in the form in which it is described in the claims, the possibility of its implementation using the means and methods described in the application and known prior to the priority date is confirmed.

Therefore, the claimed invention meets the requirement of "industrial applicability" under applicable law.

Claims (3)

1. A temperature-sensitive sensor, comprising a housing with a dielectric sleeve mounted on it on one side and a metal chamber with a heat-sensitive element rigidly mounted on it, a rod spring-loaded with the main spring, interacting with the heat-sensitive element, and a switching mechanism consisting of fixed contacts and a movable contact associated with the spring-loaded rod, and the housing and the sleeve have longitudinal guide holes, characterized in that on the mounting side metal To the chamber, the housing has an end protrusion with an opening, and the stem is supported by the base on the specified end protrusion, which covers the main spring, partially located in a recess made on the base of the rod and partially in a recess in the body of the housing, fixed contacts are made in the form of fixed in a dielectric sleeve two conductors with conductive contact pads at the ends with a gap between them, a movable spring-loaded contact, which is connected with the rod through a transmission rod installed with the possibility of free passage through the openings of the housing and its end protrusion and abutting against the stem base with one end, and placed between the contact pads of the fixed contacts with the stop in a movable contact with the other end with the insulated tip, the housing, a metal chamber, the transfer rod and the stem is made of heat resistant alloy. 2. The temperature-sensitive sensor according to claim 1, characterized in that the movable contact is made in the form of a ball, the diameter of which is selected in magnitude greater than the gap between the contact pads of the fixed contacts. 3. The thermosensitive sensor according to claim 1, characterized in that the metal chamber has a central protrusion in the form of a tube, to the end of which a thermosensitive element in the form of a cap is removably attached.

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