RU2762663C1 - Limit switch - Google Patents

Abstract

FIELD: electrical engineering.

SUBSTANCE: limit switch contains a contact system, a rotary jumper with a magnetic system, an additional magnetic system located on the outside of the housing, kinematically connected to the tracked element, as well as a torsion spring, one of the hooks of which is attached to the housing, and the other to the jumper axis. Each magnetic system is made in the form of one permanent magnet, which are magnetized in a diametrical direction perpendicular to the axis of rotation of the jumper and are oriented relative to each other by opposite poles with an offset in the initial state of the contact system by an angle exceeding the angle of rotation of the rotary jumper. The moment of rotation of the jumper, created by the interaction of permanent magnets in the extreme spatial position of the tracked element, exceeds the moment of rotation created by the torsion spring.

EFFECT: ensuring reliable contactless control of the final spatial position of the tracked element with switching electrical circuits of automation systems with significant currents.

1 cl, 5 dwg

Description

The invention relates to the field of instrumentation, in particular to automation devices that can be used to switch electrical circuits of critical technical objects.

Known contact system used as a limit switch [RF patent No. 2685543, IPC H01H 1/42, published 04/22/2019, bull. No. 12], which contains a contact system and a rotary jumper with a magnetic system placed in a sealed non-magnetic housing, as well as an additional magnetic system located on the outside of the housing, kinematically connected to the tracked element.

The contact system is presented in the form of movable elastic contacts and fixed contacts installed in pairs, placed in a housing. The jumper is equipped with permanent magnets of alternating polarity located diametrically and connected by an annular magnetic circuit, interacting with similar additional permanent magnets connected by an additional annular magnetic circuit located on a rotary bushing installed outside on the axial protrusion of the housing. The angle of rotation of the rotary sleeve exceeds the angle of rotation of the jumper, and the angular width of the magnets is not less than half the difference between the angle of rotation of the rotary sleeve and the angle of rotation of the jumper. On the stationary contacts, cantilever elements are installed with the possibility of rotation, and in the housing between each pair of movable elastic contacts, one stop made of insulating material is fixed, interacting alternately with each movable elastic contact in the initial and switched states of the contact system.

The disadvantage of this system is that this contact system can be switched only when a constant kinematic connection of the external magnetic system with the tracked element is ensured, which makes a pivotal movement through a limited angle, which narrows the scope, excluding triggering at any other movement of the tracked element. In addition, to control (turn off-turn on) switched electrical circuits with significant consumption currents and inductive load, additional equipment of the automation system, which uses a known contact system, is required with electromagnetic repeaters with contacts that ensure the switching of electrical circuits with the required currents and type of load. These features of the known contact system limit its scope.

Known contact system, taken as a prototype, also used as a limit switch [RF patent No. 2691740, IPC H01H 1/42, published 06/18/2019, bull. No. 17], which contains a contact system and a rotary jumper with a magnetic system placed in a sealed non-magnetic housing, as well as an additional magnetic system located on the outside of the housing, kinematically connected to the tracked element.

The contact system is presented in the form of movable elastic contacts and fixed contacts placed in the housing. The rotary jumper is equipped with permanent magnets of alternating polarity located diametrically and connected by an annular magnetic circuit, interacting with similar additional permanent magnets connected by an additional annular magnetic circuit located on a rotary bushing installed outside on the axial protrusion of the housing, which allows switching the contact system through the hermetically sealed wall of the casing that insulates the contact system from the influence of the external environment, and also ensures the preservation of the initial and switched state of the contact system under operating conditions. The angle of rotation of the rotary sleeve exceeds the angle of rotation of the jumper, and the angular width of the magnets is not less than half of the difference between the angle of rotation of the rotary sleeve and the angle of rotation of the jumper, which ensures the mutual displacement of the permanent magnets relative to each other with the overlap zone, which creates a reliable retention of the jumper, and, consequently, elastic contacts in closed and open states.

The known contact system has the same disadvantages as the previous analogue. This contact system can be switched only when a constant kinematic connection of the external magnetic system with the tracked element is ensured, which makes a pivotal movement through a limited angle, which limits the scope of application, excluding operation during any other complex movement of the tracked element. Also, to control (turn off-turn on) switched electrical circuits with significant consumption currents and inductive load, additional equipment of the automation system with electromagnetic repeaters with contacts is required to ensure the switching of electrical circuits with the required currents and type of load. When switching electrical circuits of automation systems with significant currents and inductive load, the contacts of the analog and prototype contact systems will have a very limited resource and will inevitably fail - either the contacts are welded or a significant increase in resistance due to "burning" of the contacts. That is, the contact system will fail and the switch will not be able to perform its function. These features of the known contact system limit its scope.

The objective of the claimed invention is to create a limit switch that reliably contactlessly controls the end position of the tracked element, regardless of the nature of its movement and the amount of movement to this position, excluding false alarms during vibration shock effects and switching electrical circuits of automation systems with significant currents in wide areas of application.

The technical result, which the claimed invention is aimed at, is to provide reliable contactless control of the final spatial position of the tracked element, regardless of the nature of its movement and the amount of movement to this position with switching electrical circuits of automation systems with significant currents.

The specified technical result is achieved in that the limit switch containing a contact system and a rotary jumper with a magnetic system placed in a sealed non-magnetic material housing, as well as an additional magnetic system located outside the housing, kinematically connected to the tracking element, according to the invention is equipped with a torsion spring, one of which hooks are attached to the body, and the other to the jumper axis, each magnetic system is made in the form of one permanent magnet, and the external permanent magnet is attached to the tracked element, while the permanent magnets are magnetized in a diametrical direction perpendicular to the jumper axis of rotation and oriented relative to each other opposite poles with a displacement in the initial state of the contact system by an angle exceeding the angle of rotation of the rotary jumper, and the moment of rotation of the jumper created by the interaction of permanent magnets in the extreme space position of the monitored element exceeds the torque generated by the torsion spring.

Equipping the limit switch with a torsion spring, one of the hooks of which is attached to the body, and the other to the jumper axis, ensures reliable (guaranteed) stable preservation of the initial state of the contact system, excluding false actuation of the limit switch, for example, in the presence of vibration and shock effects, which are inevitably present when moving the monitored element and the operation of equipment in which a limit switch is used, which allows the use of the inventive switch in critical technical objects that do not allow malfunctions.

The implementation of each magnetic system in the form of one permanent magnet, magnetized in a diametrical direction perpendicular to the axis of rotation of the jumper, allows, in comparison with the prototype, to exclude magnetic circuits from the design of magnetic systems, to halve the number of magnets (from four to two), thereby significantly increasing their volume , and, consequently, the "energy" of magnets, allowing to simplify the design of the magnetic systems of the limit switch and at the same time to increase the torque created by the magnets, which makes it possible to use and reliably (guaranteed) switch the contact system, providing switching and long-term transmission of significant currents [patent RF No. 2552349, IPC H01H 1/42, published 10.06.2015, bull. No. 16].

Placing an external magnet on the tracked element allows for non-contact control of the final spatial position of the tracked element, regardless of the nature of its movement and the amount of movement to this position.

The orientation of the magnets relative to each other by opposite poles with a displacement in the initial state of the contact system by an angle exceeding the angle of rotation of the jumper and the excess on the jumper of the moment of rotation created by the interaction of permanent magnets in the extreme spatial position of the tracked element over the torque created by the torsion spring provides reliable switching the contact system of the limit switch and subsequent reliable preservation of the already switched state of the contact system, excluding openings, for example, in the presence of vibration and shock effects and, as a consequence, possible malfunctions of the equipment in which the claimed limit switch is applied, which also expands its scope.

The above distinctive features of the inventive limit switch together provide advantages over the prototype, namely:

- no constant kinematic connection of the limit switch with the tracked element is required, reliable contactless control of the final spatial position of the tracked element is provided, regardless of the nature of its movement and the amount of movement to this position, which can be any: rotational, translational, translational-rotational, any complex;

- no additional repeaters are required - electromagnetic switches to control (turn off / on) the motion drives of the monitored element with high consumption currents, since the contact system of the inventive limit switch ensures reliable switching of electrical circuits of automation systems with significant currents.

These advantages significantly expand the operational capabilities and applications of the proposed limit switch.

The presence in the claimed invention of the features that distinguish it from the prototype, allows it to be considered as corresponding to the condition of "novelty".

New features, which contain the distinctive part of the claims, have not been identified in technical solutions for a similar purpose. On this basis, it can be concluded that the claimed invention meets the condition "inventive step".

The invention is illustrated in the drawings.

FIG. 1 shows an axial section of the limit switch when interacting with the controlled element;

FIG. 2 - section a-a in Fig. 1, the design of the contact system;

FIG. 3 - section BB in Fig. 1, the location of the permanent magnet on the jumper (the contact system is in its original state);

FIG. 4 shows the interaction of permanent magnets (the contact system is at the beginning of rotation from the initial state);

FIG. 5 shows the interaction of permanent magnets (the contact system is in a switched state).

For ease of visualization, FIG. 4 and FIG. 5, an external permanent magnet attached to a controlled element is shown conventionally displaced relative to a permanent magnet attached to the jumper axis.

In these drawings, the following designations are accepted.

1 - case;

2 - current output;

3 - contact;

4 - insulator;

5 - body block;

6 - rotary jumper;

7 - conductive knife;

8 - jumper axis;

9 - the substrate of the magnet located in the housing;

10 - permanent magnet located in the housing;

11 - external permanent magnet;

12 - torsion spring;

13 - controlled (tracked) element;

14 - limiting ledge;

15 - outer magnet holder.

The limit switch is designed as follows.

The limit switch (Fig. 1 - 5) contains a non-magnetic material housing 1, which houses the contact system and the rotary jumper 6. The housing 1, connected to the housing block 5 by a weld seam, provides the tightness of the internal volume of the limit switch to protect the contact system from external influences. Wednesday.

The contact system consists of contacts 3 fixed on current leads 2 and conductive knives 7 fixed on jumper 6, interacting with contacts 3. Current leads 2 on insulators 4 are fixed on the case block 5 and are located in a circle around the rotary jumper 6. Contacts 3 are located on current leads 2 in pairs and contact the knives 7 oppositely, providing stable electrical parameters of the contact system, and, consequently, its reliable operation under severe operating conditions of the limit switch, including vibration impact.

On the axis 8 of the jumper 6, a permanent magnet 10, magnetized in the diametrical direction perpendicular to the axis of rotation of the jumper 6, is fixed on the substrate 9, which interacts through the sealed wall of the housing 1 with an external permanent magnet 11 installed in the cage 15, which in turn is fixed, for example, by a weld, on the controlled (tracking) element 13. The holder 15 protects the external permanent magnet 11 from shock effects that can cause its chips and destruction. The external permanent magnet 11 is also magnetized in a diametrical direction perpendicular to the pivot axis of the jumper 6. The magnets 10, 11 are oriented relative to each other by opposite poles with a displacement in the initial state of the contact system by an angle γ exceeding the angle of rotation φ of the jumper 6.

The arrangement of the poles (directions of magnetization D, D) of the permanent magnets 10, 11 (Figs. 4, 5) provides a turning moment that matches the shortest pole angle S and N of the permanent magnet 10 with the poles N and S, respectively, of the permanent magnet 11, and, as a consequence, turning axle 8 and jumper 6 with switching of the contact system of the limit switch.

The limit switch is also equipped with a torsion spring 12, for example, made in the form of a spiral strip spring, with one hook fixed on the housing panel 5, with the other on the axis 8 of the jumper 6. The moment of rotation of the jumper 6, created by the interaction of permanent magnets 10, 11 in the extreme spatial position of the controlled element 13 exceeds the moment created by the torsion spring 12 over the entire angle of rotation φ of the jumper 6.

The rotation of the jumper 6 through the angle φ is limited by the protrusions 14 interacting with the substrate 9 of the permanent magnet 10.

The moment created by the torsion spring 12 is regulated by turning its outer hook. When assembling the limit switch, first, without interaction with the external permanent magnet 11, the minimum moment of the spring 12 is set, which ensures the return of the contact system from the triggered state to its original state, then the external hook of the spring 12 is additionally deployed, for example, by a third of a turn and fixed in this angular position to increase the design margin on switching the contact system during the subsequent operation of the limit switch.

The moment of rotation of the jumper 6, created by the interaction of the permanent magnets 10, 11, if necessary, can be increased by reducing the gap between the permanent magnet 11 and the end of the housing 1 in the extreme position of the monitored element 13 or by selecting permanent magnets 10, 11 with increased magnetic characteristics, for example, from materials from the nomenclature of GOST 21559 and GOST 52956.

The limit switch works as follows.

FIG. 1 shows an example of the use of a limit switch that switches the electrical circuits of an object of use when installing a special insert 13.

The magnetization of the internal and external permanent magnets 10, 11 in the diametrical directions D, D, perpendicular to the axis of rotation of the jumper 6 and their orientation relative to each other by opposite poles simplifies the design of the limit switch - the number of permanent magnets is halved (from four to two) and magnetic circuits are completely excluded. In addition, the volume of permanent magnets 10, 11 increases, and hence the moment of rotation of the jumper 6 from their interaction, which increases the reliability of the limit switch.

The displacement of the directions of magnetization of the permanent magnets 10, 11 by a fixed angle Δ in the switched state of the contact system makes it possible to maintain this state under external vibro-shock influences.

In the initial state of the contact system (in the initial angular position of the jumper 6), the magnetization directions of the permanent magnets 10, 11 (D and D, respectively, Fig. 4) do not coincide by an angle γ exceeding the angle of rotation φ of the jumper 6, due to this, a moment is provided that turns the jumper 6.

That is, at the beginning of the rotation of the jumper 6 from the interaction of the permanent magnets 10, 11, the angle between the magnetization directions of the permanent magnets 10, 11 (D and D, respectively, Fig. 4) is, for example, 45 °. After turning the jumper 6 by an angle φ, for example equal to 30 °, the permanent magnets 10, 11 will be displaced by the remaining 15 ° = 45 ° - 30 °. Due to this displacement, the contact system of the limit switch will be reliably held in the switched state.

The largest and smallest value of the angle y to ensure reliable switching and subsequent reliable preservation of the switched state of the contact system (taking into account the condition that the moment of rotation of the jumper 6, created by the interaction of permanent magnets 10, 11 in the extreme spatial position of the monitored element 13, exceeds the moment of rotation created torsion spring 12) may exceed the value of the angle of rotation of the jumper 6, for example, by 10-15 °.

With a decrease in the angle γ, the resulting torque at the beginning of the rotation of the jumper 6 increases and the resulting torque of holding the contact system in the switched position decreases.

With an increase in the angle γ, on the contrary, the resulting moment at the beginning of the rotation of the jumper 6 decreases and the resulting moment of holding the contact system in the switched position increases.

At the beginning of the rotation of the jumper 6 from the interaction of the permanent magnets 10, 11, the angle γ between the directions of magnetization of the permanent magnets 10, 11 (D and D, respectively, Fig. 4) is γ = φ + Δ, where φ is the angle of rotation of the jumper 6 required to switch the contact systems (for example, φ = 30 °), Δ is the angle between the directions of magnetization of permanent magnets 10, 11 (D and D, respectively, Fig. 5) in the switched state of the contact system (for example, Δ = 10-15 °). With the indicated values of the angles φ and Δ, the angle γ can take values from 40 to 45 °, providing both reliable retention of the jumper 6 in the switched state of the contact system, and a sufficient moment required to turn the jumper 6 from its initial angular position corresponding to the initial state of the contact systems.

With the translational movement of the controlled element 13 to the extreme spatial position from the interaction of the permanent magnets 10, 11, the jumper 6 is rotated through the angle φ (Fig. 2) until the substrate 9 stops in the protrusion 14 (Fig. 3), and the contact system is switched. The presence of the orientation angle of the magnets 10.11 relative to each other by opposite poles offset by an angle Δ (Fig. 5) in the switched state of the contact system provides a torque that reliably holds the contact system in the switched state under all operating conditions, including vibration impacts.

When the controlled element 13 is removed from the limit switch installation zone, the spring 12 returns the jumper 6, and, consequently, the contact system to its original state, ensuring that this state is reliably maintained under all operating conditions.

As a result, the inventive limit switch provides reliable contactless control of the final spatial position of the monitored element 13, regardless of the nature of its movement and the amount of movement to this position, excludes false alarms during vibration shock effects and switches electrical circuits of automation systems with significant currents.

The limit switch has advantages over known devices:

- no constant kinematic connection of the limit switch with the controlled element 13 is required;

- the actuation of the limit switch is ensured at the final spatial location of the controlled element 13, regardless of the type of its movement when moving to this location, which can be any: rotational, translational, translational-rotational, any complex;

- the design of the contact system with reliable paired contacts 3 provides control (disconnection / connection) of power devices with high consumption currents without the use of additional repeaters - electromagnetic switches.

These advantages significantly expand the scope of the inventive limit switch.

At present, the design documentation has been developed, prototypes of the limit switch made in accordance with the claimed invention are being manufactured. The performance of the proposed limit switch is confirmed by calculations.

The presented information testifies to the fulfillment of the following set of conditions when using the claimed invention:

- the claimed limit switch relates to the field of instrumentation, in particular to automation devices that can be used to switch electrical circuits of critical technical objects;

- the inventive limit switch, when used, is capable of providing reliable contactless control of the final spatial position of the tracked element, regardless of the nature of its movement and the amount of movement to this position with switching electrical circuits of automation systems with significant currents;

- for the inventive limit switch in the form in which it is described in the claims, the possibility of its implementation is confirmed using the means and methods described in the application and known before the priority date.

Therefore, the claimed limit switch meets the "industrial applicability" condition.

Claims (1)

A limit switch containing a contact system and a rotary jumper with a magnetic system placed in a sealed non-magnetic material case, as well as an additional magnetic system located on the outside of the case, kinematically connected to the tracked element, characterized in that it is equipped with a torsion spring, one of the hooks of which is attached to the case, and the other - to the jumper axis, each magnetic system is made in the form of one permanent magnet, and the external permanent magnet is fixed on the tracked element, while the permanent magnets are magnetized in a diametrical direction perpendicular to the jumper rotation axis and are oriented relative to each other by opposite poles with an offset in the initial state of the contact system by an angle exceeding the angle of rotation of the rotary jumper, and the moment of rotation of the jumper created by the interaction of permanent magnets in the extreme spatial position of the tracked element exceeds the moment of rotation created by the torsion spring.

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