RU2115895C1 - Magneto-contact temperature-sensitive element - Google Patents

Abstract

FIELD: measurement technology, continuous monitoring of temperature level. SUBSTANCE: given temperature-sensitive element has metal diamagnetic air-tight case that houses dielectric bushing. Twin conductor connected to immobile contacts is made fast to bushing. Contacts are interbridged by means of mobile current conductive jumper. Dielectric bushing is fixed in case over its perimeter by shaped nut-plug. Immobile contact are built into magnetic circuit. Magnetic circuit is made of two parts in the form of round segments from thermomagnetic alloy, for instance, from Fe-Ni-Co with Curie point θ_c= +70^°C= +70 C. Mobile current conductive jumper is produced as mobile contact in the form of permanent magnet having shape of cylinder manufactured from magnetically hard material ( (θ_c= +870...900^°C).=+870-900 C ). Permanent magnet has surface contact layer in the form of ring made from current conductive material in working zone. Center of mobile closing contact is kinematically coupled to direct-stroke rod and compression spring installed in central hole of dielectric bushing closed on outer butt by blank washer with lockpin. Usage of magneto-sensitive element and compression spring in temperature-sensitive element results in its miniaturization and in compensation of gravity forces under certain positions of element. EFFECT: enhanced operational reliability. 5 dwg

Description

 The present invention relates to contact temperature sensors that are installed on various devices and mechanisms (or on their individual critical parts) for constant monitoring of the temperature level (for example, on axle boxes of cars and locomotives, various gearboxes, on semiconductor converters, etc.) and which signal when exceeding the permissible heating value of the device.

 The term "sensor" in the general case means a cheap and reliable receiver and a converter of a measured physical quantity (in this case, the heating temperature) into an electrical signal at the output.

 There are a large number of different designs and devices used as temperature sensors, but all of them have some significant disadvantages that impede their widespread use.

 Known analogues include a contact temperature sensor (see L. Tereshkin, “Drives of Passenger Car Generators.” Transport, Moscow, 1990, p. 30; 31, fig. 23, fig. 22 and fig. 21, pos. 7 ), which is a rigid brass sealed case with an internal ebonite sleeve, into which the ends of two wires isolated from each other, which from the outside go to the electrical panel in the compartment of the conductor or the driver’s panel, and on the other hand, the bare ends of the wires in the sleeve of the temperature sensor housing bridged by fusible alloy (see Fig. 23, according to z. 4), and from the end the housing is deafly closed (sealed) with a washer.

 Such a contact temperature sensor is screwed into the housing of the device under control in the most heated area, for example, at the place of installation of the bearings.

 The temperature sensor is powered from the battery voltage of 50 V so that the relay coil of the relay is energized, and the relay block contacts are open and the power supply circuit of the signal bell and lamp is broken (de-energized).

When the case of the controlled device is heated above +70 ^o C (up to 90-100 ^o C), the low-melting alloy melts and flows to the bottom of the body under the influence of gravity, while the electrical contact between the ends of the wires is broken, the RP relay is de-energized, its block contacts are closed, the signal bell and lamp turn on.

Such a contact temperature sensor has the following significant disadvantages:
a) fusible alloy contains: Bi - 51.65%; Pl - 40.2%; Cd is 8.15% and is a rather expensive alloy;
b) it is not sensitive enough, since the fusible alloy is separated from the heat source from the sides by insulation, and from the end - by a layer of air (distance);
c) after operation, the sensor must be replaced with a new one, i.e. it cannot be easily restored;
d) at temperatures of the controlled device close to the melting temperature of the fusible alloy, it may be severely softened and false (premature) tripping;
e) completely non-universal, i.e. it cannot, for example, be installed on an object in zero gravity.

 The closest in its technical essence and purpose to the proposed technical solution is “Contact thermal sensor for railway rolling stock” according to the application RU 94-042880 (043135), 10.10.96, according to which the decision to grant a patent of the Russian Federation was made by the VNIIGPE expert examination on 10.10.95.

 The contact temperature sensor according to this application is a rigid brass sealed housing, with a double insulating sleeve installed inside it, representing the upper and lower bushings, made of mechanically strong and heat-resistant plastic.

 The housing has an external thread and a hexagonal flange for gripping with a wrench during installation and through it through the neck a two-core insulated wire and is rigidly fixed (rolled).

 In the upper sleeve, fixed contacts are rigidly mounted (pressed), which are connected (soldered) to the internal bare ends of the wire.

 These fixed contacts are closed by a conductive bridge of a solid-metal movable contact, which is rigidly mounted in the center of the power elements, using a special double-sided rivet.

 The power element is made of a material with a reversible thermal shape memory or of bimetal in the form of a curved round thin-walled spherical diaphragm.

The specified power element with its edges rests on the ends between the upper and lower insulating sleeves and is fixed with a lock shaped nut. The shaped nut has two key holes and, after screwing it into the body, heels at three points at an angle of 120 ^o C around the perimeter of the thread.

The power element in the initial position (at temperatures up to +70 ^o C) is installed by pressing between the fixed contacts and the movable contact.

 The contact temperature sensor is screwed into the controlled object until it stops, and the outer end of the wire goes through the connector to the console in the compartment of the conductor or driver in the signal circuit.

During operation, when the temperature of the monitored unit reaches a value above +70 ^o C (i.e. approximately + 90-100 ^o C), the power element discretely changes its shape, i.e. bends in the opposite direction in the direction of the arrow and between the contacts and a solution forms, i.e. contacts open. At the same time, the power coil of the relay, which closes the block contacts, is de-energized, a signal lamp flashes and a bell rings on the console of the conductor or the driver.

When the power element is cooled to its original temperature (below +70 ^o C), it returns to its original position, closing the alarm electrical circuit. The sensor is ready for further work.

The described prototype is a perfect and reliable device, however, and it has some disadvantages:
f) the power element has a round shape and a relatively large diameter, which causes, respectively, an increase in the diameter of the device casing and prevents its miniaturization;
g) the technology for the production of a power element from a metal with memory, with given parameters, is quite complicated and requires special production.

 The objective of the invention is the creation of a magnetic contact temperature sensor, free from the above disadvantages (see paragraphs "e"; "g").

The problem is solved in that the proposed device contains fixed contacts made of well-conductive material (for example, copper, etc.), which are rigidly installed (for example, screwed in), each in its own section of the magnetic circuit so that their ends slightly protrude outward lower the surface of the magnetic circuit with its contact part. Moreover, the specified magnetic circuit consists of two parts (each of them contains its own fixed contact), made (in plan) in the form of circular segments, with a gap to each other, from a thermomagnetic alloy (for example, from Fe-Ni-Co with a Curie point: θ _K = +70 ^° C) and are installed rigidly together with fixed contacts in the inner end of the dielectric sleeve.

The closing contact is a movable contact, which is a strong permanent magnet made in the form of a flat cylinder of hard magnetic material (for example, alnico or magnico and others with a Curie point: θ _к = + 870-900 ^° C), if necessary, with a thin surface contact layer of well-conducting material in the form of a ring (for example, of brass or bronze foil or obtained by the galvanic method, etc.), from the contacting side (in the Fig. top of the magnet) rigidly connected to the surface of the magnet (for example, with help glue, galvanic method, etc.).

 In the initial position, the make contact is located in the center, inside the lower part of the dielectric sleeve, on the fixed contacts, bridging (closing) them.

 In the center of the dielectric sleeve there is a return straight-through rod with a compression spring, closed at the end with a blind washer with a pin.

 The dielectric sleeve with fixed and movable contacts and a two-wire wire from them are installed in a diamagnetic metal case (for example, made of brass, etc.) and are closed from the end with a dummy nut, also made of diamagnetic material.

The novelty of the invention lies in the fact that for the closing and opening of the contacts, the above-mentioned thermomagnetic alloy (from the Curie point: θ _to = +70 ^° C) and a strong permanent magnet of hard magnetic material (with θ _to = + 870-900 ^° C), and the specified thermomagnetic alloy when heated above +70 ^o C lose their magnetic properties, and when cooled below +70 ^o C it acquires them again.

 Thus, due to the use of these magnetic materials to control contacts, new properties appear, such as, for example, independence from the influence of gravitational forces, ease of manufacture, self-healing for continued operation, low cost, simplicity of manufacturing technology, versatility, reliability.

The technical and economic advantages of the proposed technical solutions include:
h) the device can be installed in any operating position at a controlled facility;
i) when the device is cooled to normal (below +70 ^o C) temperature, it automatically returns to its original position, in a state of readiness for work;
j) the operation of the device does not depend on the influence of gravitational forces;
k) the device is simple in design and has a minimum number of parts;
m) the device is easy to manufacture and cheap;
m) switching occurs discretely, instantly;
o) the device is maintainable and its parts are interchangeable;
o) the device is universal, i.e. can work at various controlled facilities;
p) the device is highly reliable in operation;
c) the device is reliably protected from external influences;
r) the device can be performed at other operating temperatures.

In FIG. 1 shows a magnetocontact temperature sensor in cross section along the vertical axis, in the operating state, i.e. at a temperature below +70 ^o C; in FIG. 2 shows a temperature sensor in cross section along AA (view of fixed contacts); in FIG. 3 shows a temperature sensor in section along BB (view of a movable contact); in FIG. 4 shows the temperature sensor in a bottom view in the direction of arrow B; in FIG. 5 shows the temperature sensor in longitudinal section along the vertical axis, in the off position at temperatures above +70 ^o C.

 In the figures, the letters denote: L is the total length of the sensor (without wires); l is the length of the threaded part; S is the size of the wrench; d is the diameter of the threaded part; δ — contact solution; γ is the gap between the circular segments of the magnetic circuit; α is the gap between the movable contact and the bottom of the housing in the on position of the contacts.

 The proposed magnetocontact temperature sensor (see Fig. 1, 2, 3, 4 and 5) contains a durable sealed diamagnetic metal housing 1 (for example, made of brass) with a dielectric sleeve 2 installed inside it, made of mechanically strong and heat-resistant plastic (for example , from plastic of the brand AG-4, etc.).

 The housing 1 has an external thread and a hexagonal flange for gripping with a wrench during installation, and a two-core insulated wire 4 is inserted into it through the neck 3 and is rigidly fixed (for example, by rolling along the neck 3). In the dielectric sleeve 2, fixed contacts 5 (for example, made of brass and others) are rigidly installed (for example, pressed in), together with each part of the magnetic circuit 6, and the contacts 5, for example, are screwed into the magnetic circuit 6, so that the ends several of them protrude outside the lower surface of the magnetic circuit 6 with their end contact part.

 To the opposite side of the fixed contacts 5 are rigidly attached (for example, soldered) bare end ends 7, wires 4.

The indicated sections of the magnetic circuit 6 are made (if you look at them in plan, see Fig. 2) in the form of circular segments, from a well-machined, thermomagnetic alloy (for example, from Fe-Ni-Co with Curie point: θ _to = +70 ^° C) and installed with a gap γ between themselves in the dielectric sleeve 2 and closed by a movable conductive jumper, which is a movable contact 8 in the form of a strong permanent magnet, in the form of a round tablet (i.e., a flat round cylinder, where its height is approximately , radius), of hard magnetic material (for example y, "Alnico" or "Magnik", etc. with a Curie point:. θ _a = + 870-900 ^° C).
If necessary, to improve the electrically conductive properties during contacting, it is possible to reinforce the movable contact 8 with a thin surface contact layer of a well-conductive material in the form of a ring (with an outer diameter equal to the diameter of the contact 8) made, for example, of brass or bronze foil or obtained by galvanic method and others from the contacting side (in Fig. on top of the magnet), rigidly connected to the surface of the magnet (for example, using glue, galvanically, etc.).

 The movable contact 8 is located in the center, inside the lower part of the dielectric sleeve 2, on the fixed contacts 5, bridging (closing) them.

 The center of the movable contact 8 is kinematically connected with the linear piston rod 9 and with a strained compression spring 10, which are installed in the Central hole 11 and the dielectric sleeve 2, through a blind hole 12 in the movable contact 8, which includes the end 13 of the linear rod 9.

 From the end, the hole 11 is closed by a blind washer 14, which is fixed, for example, by a pin 15.

 The dielectric sleeve 2 with fixed contacts 5 and the magnetic circuit 6, which in the initial position are closed by the movable contact 8 (in this case, the straight-through rod 9 abuts against it and compresses the spring 10), is fixed in the housing 1 with the help of a dummy nut 16, which is also made of of a diamagnetic and heat-conducting metal (for example, made of copper, brass, etc.) and screwed (using turnkey blind holes 17) into the lower end of the housing 1 and together with it protects and shields the sensor contact system, from the inside between the shaped Coy stopper 16 and the movable contact 8 is working gap α. To adjust the value of the working solution δ, installation of shims 18 is possible.

 If necessary, all parts of the device must have appropriate coatings.

After installing the blanking nut 16 in the housing 1, it is fastened or minted around the perimeter of the thread, for example, at 3 points at an angle of ≈120 ^o C to each other.

 The magnetocontact temperature sensor is screwed with a gasket (for example, from paronite, etc.) into the controlled object as far as it will go and the free end of wire 4 through the ballast (plug connector not shown in Fig.) Goes to the control panel, where it is connected, for example, according to the known circuit (see analogue, p. 31, fig. 22) to the signal elements.

и т.д.) позволяет соответственно получить целую серию магнитоконтактных термодатчиков, реагирующих на различные температуры срабатывания при нагреве контролируемых объектов. Но наибольшее техническое применение получили сплавы Fe-Ni-Co c θ_к= +70^°C.
При работе (см. фиг. 5), температура от контролируемого объекта передается гайке-заглушке 16 и корпусу 1, в результате чего нагревается магнитная система датчика, и при достижении магнитопроводом 6 нагрева выше +70^oC (θ_к= +70^°C) магнитопровод 6 полностью теряет свои магнитные свойства.It should be further noted that during the manufacture and installation of a magnetic circuit 6 from other thermomagnetic alloys (i.e. alloys with other components and with a different percentage in the alloy and with different values of the Curie point temperature) in the magnetocontact thermal sensor:

etc.) allows, accordingly, to obtain a whole series of magnetocontact thermal sensors that respond to different temperatures of operation when heating controlled objects. But the greatest technical application was received by Fe-Ni-Co alloys with θ _к = +70 ^° C.
During operation (see Fig. 5), the temperature from the controlled object is transferred to the dummy nut 16 and the housing 1, as a result of which the magnetic system of the sensor is heated, and when the magnetic circuit 6 reaches heating above +70 ^o C (θ _to = +70 ^° C ) the magnetic circuit 6 completely loses its magnetic properties.

As a result of this, and under the influence of the efforts of the compression spring 10, through the linear rod 9, the movable contact 8 (which is a strong permanent magnet with θ _к = + 870-900 ^° C) breaks away from the magnetic circuit 6, i.e. opens the fixed contacts 5, and a solution δ is formed between the contacts.

 At the same time, the power coil of the RP relay is de-energized and, disconnecting, closes the power circuit of the bell and signal lamp with its block contacts, which notifies about the overheating of the controlled object.

When the magnetic elements of the magnetocontact temperature sensor are cooled to the initial lowered temperature (i.e., below +70 ^o C), the movable contact 8 (permanent magnet) closes the fixed contacts 5 (since the magnetic circuit has regained its magnetic properties), restoring the electrical circuit to turn on the temperature sensor to its original position and between the movable contact 8 and the dummy nut 16 a gap α is formed (in this case, α = δ).

 It is most rational to use the proposed device, for example, in railway transport on the drilling units of wagons and locomotives, various gearboxes and gears, and, in general, on any machines where constant monitoring of the permissible temperature level is necessary: bearing housings, etc., especially when you consider that magnetocontact thermal sensors can be manufactured at different response temperatures during overheating of controlled objects.

 Given the above advantages (see paragraphs: "h"; "and"; "k"; "l"; "m"; "n"; "o"; "p"; "p"; "s"; "t "), especially the low cost, simplicity of design and the reliability of the device, it is advisable to upgrade, for example, in railway transport the old contact temperature sensors known for their shortcomings and arrange the release of new ones, since these costs will quickly pay off during operation, and the use of the proposed magnetic contact thermal sensor will give significant economic the effect.

Claims (1)

A magnetocontact thermosensor containing a metal diamagnetic sealed case with a dielectric sleeve installed in it, in which a two-wire wire is rigidly fixed, connected to fixed contacts at the end of the specified dielectric sleeve, which are interconnected by a movable conductive jumper, and the dielectric sleeve is fixed in its housing along its perimeter with using a dummy nut, characterized in that the fixed contacts are integrated in a magnetic circuit made of two pieces in the form of circular segments of the thermomagnetic alloy (for example, of Fe-Ni-Co with a Curie point: θ _a = +70 ^o C) and their ends protrude outside the bottom surface of the magnetic core and the movable conductive bridge is a movable contact in the form of a permanent magnet, made in the form of a cylinder, of magnetic hard material (with a Curie point, for example, θ _k = +870 - 900 ^o C) if necessary with a surface contact layer in the working contact zone of the conductive material, in the form of a ring, and center of movable make contact ki nematically connected to the linear rod and compression spring installed in the central hole of the dielectric sleeve, closed from the outer end with a blind washer with a pin.

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