WO2018112484A1

WO2018112484A1 - Thermobimetallic relay

Info

Publication number: WO2018112484A1
Application number: PCT/AM2017/000002
Authority: WO
Inventors: Armen Antonyan; Hayk Margaryan
Original assignee: Armen Antonyan
Priority date: 2016-12-19
Filing date: 2017-04-26
Publication date: 2018-06-28
Also published as: EA033328B1; EA201800001A1

Abstract

The invention refers to the electrical automatic control and regulating equipment. The thermobimetallic relay has a bowl-shaped metal body, a cover made of electro insulating material, a box formed in the result of their connection and two fixed contacts placed therein, which are evenly fastened in the cover with their leads. The relay is also provided with an electro conductive bridge which interacts with fixed contacts from one side and with the spring connecting the electro conductive bridge with the fixed contacts from the other side. A thermosensitive bimetal disk is placed on metal thrust collar installed on the bottom of the body with the possibility of free positioning within the box. A ball-shaped pusher made of insulating material is placed between the disk and the bridge. A guiding-insulator detaching the bimetallic disc from the group of contacts is paced in the box, and the bridge and the spring are placed in the notch formed between the fixed contacts and the cover. The safety of relay operation increases.

Description

Thermobimetallic relay

Technical Field

The invention is related to electric devices of automatic control and adjustment and adopted for switching on and off of electric network under temperature deflection of the controlled environment from the set point.

Standard requirements to such relays are small dimensions, electrical safety, hermeticity, simple assembling in devices, thermal processes which are controlled, time proof and affordable price.

Bimetallic strips are used in known thermobimetallic relays as thermal detectors monitoring temperature of controlled objects, putting into operation a mechanism switching off electric current passing through controlled objects under temperature deflection from the set point.

A change-over-mechanism usually contains movable and fixed contacts or fixed contacts and a contact bridge which closing and opening implements switching on and off of electrical current. Each opening of the contacts brings to occurrence of electric arc between these contacts and causes damage of contacts surface under the impact of heat produced by the arc. Background Art

The known thermorelay [1] which contains a thermosensitive element from the material with memory in the shape of arc and affixed by one end in the body, U-shaped contact clip with a spring controlled catch and a slot made in one of its branch where the other end of arc of the thermosensitive element is disposed affixed in the cheek of the body, contact strip with a slot in which one end of the contact clip is set, the other end of which is driven into the fixed contact and the spring controlled catch is set into the slot disposed in the cheek of the body opposite to the cheek of fastening of the contact strip as well as the adjusting screw for setting of temperature of operation through change of spring power of the contact clip.

Shortcomings of the known thermorelay are complicated precision implementation of junction of interaction of the contact clip end and the slot of the contact strip ensuring mutually exclusive conditions - safe electrical contact of the contact clip end with contact strip and free movement of the contact clip end in the slot of the contact strip.

Usage of the known thermorelay for breakup of direct-current-circuit axes service life of thermorelay as if it is even possible to put out the electrical arc between movable and fixed contacts effectively (for example, through opening of contacts at high speed-up for long distances which brings to enlargement of dimensions), avoid sparking in the junction of interaction of the contact clip end and the slot of the contact strip bringing to inoperativeness is not possible.

The known thermorelay [2], contains a dielectric body, a metal cover, fixed and movable contact clips contacting a metal cover contact post which is a thermosensitive element at the same time, made from material with the effect of the shape memory in the form of bent plate, forward-bent on the end, non-contacting part of which a slot is carried out, double throw spring one end of which is disposed in the slot of the contacting post and the other is abutted upon the movable contact clip and the adjusting screw installed from the trailing side of the contact of the movable contact clip.

Shortcomings of this thermorelay is complexity of setting of interaction junction of the double-throw spring and the movable contact clip as unsteady position of the movable contact clip can be set up through shift of bearing point of any of the two ends of the double-throw spring; incomplete galvanic isolation bringing to offence of electrical safety conditions because of the electrical connection through the double-throw spring and the thermosensitive element of the movable contact clip with the metallic cover. Besides it usage of small size version of carrying out of the known thermorelay for breakup of direct- current-circuit axes operation life of thermorelay as it is not possible to put out the electrical arc between movable and fixed contacts effectively.

The known thermorelay [3] contains a body made from electrical insulation forming a box. A thermosensitive element, a switching mechanism and a device of their interaction are installed in the box. Stop and restrictive lugs (protrusions) are made on the foundation of the box in the opposite parts of each other. Two contact posts are built-in the foundation of the box made from strip material outer portions of which form electrical leads. Intra-box part of one post, turned back surface of which is parallel to the surface of the restrictive lug and disposed over it is a contact clip of the fixed contact. Intra-box part of the other post made in the shape of one-grip loop with a grip fixed on the surface of the stop lug with an arc part in the shape of right-angled-trapezium with height equal to the height of the lug foundation with inclined cheek bonding the grip and the small foundation of the trapezium joining the box foundation and with perpendicular cheek supplied with a slot on the end which is a loop - holder of the movable contact clip.

The switching mechanism contains a fixed contact installed on the contact clip of the fixed contact with orientation of the operating surface to the side of the restrictive lug surface; the movable contact installed on a spring-controlled, double- throw spring, a catch, the movable contact clip disposed within the gap between the fixed contact and the surface of the restrictive lug; and the loop - holder of the movable contact clip, the grip of which is connected with the movable contact clip, the one end of the double-throw spring is disposed in the slot and the other end of which is abutted against the catch of the movable contact clip.

The thermosensitive element is made from the material with the effect of memory of the shape or in the form of arc one end of which is fixed in the body and the other is abutted on the movable contact clip with ability to adopt a rectilinear shape or in the form of the arc passed through bore in the wedge of the device of interaction and abutted on the slot in opposite walls of the body by free ends.

The device of interaction contains an adjusting screw and a pusher made in the form of wedge with through bore concealed in the slots of the body with possibility of movement and disposed between the adjusting screw and the movable contact clip.

Shortcomings of relay are complexity of the design, incomplete galvanic isolation bringing to offence of electrical safety, short operating life under usage for break of direct- current circuit.

The listed shortcomings are related to the following constructive decisions. Safe functioning of the relay is conditioned by sharp snap action of movable contact clip opening movable and fixed contacts with maximum speed-up.

In the relay an effort generated by the thermosensitive element is regulated and transferred to the movable contact clip which is rather complicated by itself.

Under reaching of the highest temperature of operation the thermosensitive element makes an effort exceeding an effort of resistance of the movable contact clip which partially selecting its spring power reaches the point of unsteady state and sharply by a click moves aside from the fixed contact.

During approach of the movable contact clip to the point of unsteady state pressure between fixed and movable contacts weakens which brings to increase of electrical resistance between contacts and as a result to heating up of the latter ones.

In order to eliminate heating up of the contacts it is required to reduce time for preparation of the movable contact to the click as much as possible. This also can be achieved through specially made and set in a complicated manner movable contact clips usage.

Incomplete galvanic isolation bringing to offence of electrical safety conditions and caused by that thermormosensitive element directly or through the pusher from the conducting material contacts the movable contact clip which is at the same time a current- conducting spring.

For breakup of direct-current-circuit axes operation life of thermorelay as it is not possible to put out the electrical arc between movable and fixed contacts effectively, only at the account of click-type opening of fixed and movable contacts.

The closest technical solution is the thermorelay [4] selected as an analogue. This relay has metal bowl-shaped with a two-stage cylindrical cap on one side having a cover from electro insulating material, a box formed in the result of their linking where two fixed contacts are placed which are with their leads evenly fastened in the cover's body - between its edge and the cylindrical cap, electro conductive bridge which interacts with fixed contacts from one side and from the other side on diametrically opposite edges has lug stoppers, thermosensitive bimetal disk placed with free orientation on the surface of electro conductive bridge with lug stoppers in the formed space and a spring connecting electro conductive bridge with fixed contacts, it has a central support and electro conductive bridge interacting with external edge while electro conductive bridge, bimetal disk and a spring have central holes and cylindrical caps forming first and second levels of the cover are installed respectively in holes of electro conductive bridge and bimetal disk and the spring is placed between electro conductive bridge and thermosensitive bimetal disk and its support is fastened to the interim platform of the cover's two-stage cylindrical cap. Shortcomings of the closest analogue are as follows:

Not sufficient safety of relay operation as bimetal disk placed in immediate space of fixed contacts which can bring to spontaneous heating from contacts producing heat caused by transfer resistance of contacts

The disk is separated from heat-transmitting level by air bed which worsens heat transmission and temperature control time which worsens safety of relay operation either.

Disclosure of Invention

The goal of the invention is increasing of relay operation safety.

Essence of the invention is that in thermobimetallic relay which has a bowl-shaped body, a cover made of electro insulating material, a box formed in the result of their linkage and two fixed contacts placed in it, which are with their leads evenly fastened in the cover, an electro conductive bridge which interacts with fixed contacts from one side and with the spring connecting the electro conductive bridge with the fixed contacts from the other side, thermosensitive bimetal disk placed in the box with the possibility of free positioning. According to the invention bimetal disk is placed on metal thrust collar installed on the bottom of the bowl-shaped body, a ball-shaped pusher made of insulating material is placed between the bimetal disk and the bridge, the guiding-insulator, detaching the bimetallic disc from the contacts, is paced in the box, and the bridge and the spring are placed in the notch between the fixed contacts and the cover.

Brief Description of Drawings

The essence of the invention is clarified on drawings 1-3 where:

Picture 1 shows the section of the relay with turned off contacts,

Picture 2 shows the section of the relay with I-I line of pic. 1,

Picture 3 shows the section of the relay with connected contacts.

Best Mode for Carrying out the Invention

Thermobimetallic relay consists of the following parts: bowl-shaped body (1) and cover (2) made of electro insulating material which being connected to the body forms a box (3). Two fixed contacts (4) are fastened to the cover, their upper parts being connected to electro leads (5) and covered with insulating mixture

(6), and lower parts are in the box (3), forming a narrow notch (7) between them and the cover (2) where the spring (8) and electro conductive bridge (9) are placed. Metal thrust collar (10) is placed on the bottom of the body, whereon a thermosensitive bimetal instant disk (11) is applied, with the possibility of free positioning within the box (3) on vertical flatness. The ball-shaped pusher (12) made of insulating material is placed in the central part of the disk, which contacts the bridge (9) by its surface inverse to the disk (11). The body (1) has a guiding-insulator (13) which separates bimetal disk from the group of contacts significantly reducing self-heating of thermosensitive bimetal disk that increases precision of temperature control of the controlled environment. All this increases safety of the relay.

The relay is operated the following way:

Under increase of the temperature, until reaching functional temperature, thermosensitive instant bimetal disk (11) changes the bow slowly. At that, since it is placed freely in positioning space, the slow change of bow does not cause occurrence of interaction of forces with the ball-shaped pusher (12), electro conductive bridge (9) and the spring (8). The spring (8) presses the electro conductive bridge to fixed contacts (4) with the previous force. In case of reaching the functional temperature the instant bimetallic disk (11) sharply, instantly changes its form to the inverse. The dome of the thermosensitive instant bimetallic disk interacts with ball-shaped pusher (12) causing forces which can overpower the pushing force of the spring (8). In the result the electro conductive bridge (9) is extruded out of the fixed contacts (4) and they turn off. Further increase of the temperature does not cause the change of configuration of interacting elements, and the contacts (4) continue to be off. The contacts are off until the temperature is reduced to retrospective temperature. The thermosensitive instant bimetallic disk (11) instantly changes its shape to the inverse when the retrospective temperature is reached. The dome of the thermosensitive instant bimetallic disk is detached from the ball-shaped pusher (12) without applying any pressure onto the electro conductive bridge (9) and the spring (8). The thermosensitive instant bimetallic disk is placed freely in positioning space. The spring moves the electro conductive bridge and presses to the fixed contacts by connecting them.

Bibliographic sources.

1. Patent of the Russian Federation 2439735, ΜΠΚ H01H37/54

2. Patent of the Russian Federation 2130666 , ΜΠΚ HO 1 H37/54

3. Patent of the Russian Federation N°- 2011238, ΜΠΚ H01H37/54

4. Patent of RA 1679 UTO H01H 37/54

Claims

Thermobimetallic relay which has a bowl-shaped metal body , a cover made of electro insulating material, a box formed in the result of their connection and two fixed contacts placed therein, which are evenly fastened in the cover with their leads, an electro conductive bridge which interacts with fixed contacts from one side and with the spring connecting the electro conductive bridge with the fixed contacts from the other side, a thermosensitive bimetal disk placed in the box with the possibility of free positioning; is characterized in that the bimetal disk is placed on metal thrust collar installed on the bottom of the bowl-shaped body, a ball-shaped pusher made of insulating material is placed between the disk and the bridge, the guiding-insulator detaching the bimetallic disc from the contacts is paced in the box, and the bridge and the spring are placed in the notch formed between the fixed contacts and the cover.