Electromagnetic mechanism

Abstract

An electromagnetic mechanism includes a coil, an iron core arranged in the coil, an outer magnetic yoke and an inner magnetic yoke, wherein the inner magnetic yoke is located between the coil and the outer magnetic yoke; a permanent magnet is arranged on the inner magnetic yoke; an inner bending foot that is bent in a direction of the iron core is arranged on a side of the inner magnetic yoke close to the iron core; the inner bending foot is provided with an avoidance groove for avoiding the iron core; and a first air gap is formed between the periphery of the iron core and the inner bending foot. Since the inner bending foot of the inner magnetic yoke is provided with the avoidance groove for avoiding the iron core, the first air gap in contact with the inner magnetic yoke is formed around the iron core, and a new magnetic circuit is formed outside the inner magnetic yoke through the first air gap. The new magnetic circuit is attracted by the permanent magnet, which can not only ensure the attraction and release characteristics, but also eliminate the need to use a gasket, thereby avoiding the problems of increased assembly difficulty, size-control difficulty and large assembly errors caused by the gasket.

Description

TECHNICAL FIELD

[0001] The present invention relates to the field of low-voltage electrical appliances, and more particularly to an electromagnetic mechanism.BACKGROUND

[0002] As a driving component, an electromagnetic mechanism is widely applied in various control appliances, and generally includes a support, a moving member, a static member, a coil and an elastic member. The coil can form an electromagnetic force between the moving member and the static member so as to drive the moving member to move against an acting force of the elastic member. After the electromagnetic force formed by the coil disappears, the moving member can move in an opposite direction under the drive of a restoring force of the elastic member.

[0003] When a permanent magnet is used in a DC electromagnetic mechanism, in order to reduce magnetic flux leakage, a gasket is usually used to form an air gap between the moving member and the static member, so as to achieve reliable attraction and release characteristics. However, since the thickness of the gasket is usually relatively thin, the gasket itself is prone to deformation, which leads to the increase in the assembly difficulty of the electromagnetic mechanism. In addition, the gasket also has the problems of difficulty in size control and large assembly error, which then affects the working stability of the electromagnetic mechanism.SUMMARY

[0004] An object of the present invention is to overcome the defects of the prior art, and provide an electromagnetic mechanism that requires no gaskets, has low precision requirements, and has reliable attraction and release action characteristics.

[0005] In order to achieve the above objects, the present invention adopts the following technical solutions: An electromagnetic mechanism, comprising a coil, an iron core arranged in the coil, an outer magnetic yoke and an inner magnetic yoke, wherein the inner magnetic yoke is located between the coil and the outer magnetic yoke; a permanent magnet is arranged on the inner magnetic yoke; an inner bending foot that is bent in a direction of the iron core is arranged on a side of the inner magnetic yoke close to the iron core; the inner bending foot is provided with an avoidance groove for avoiding the iron core; and a first air gap is formed between the periphery of the iron core and the inner bending foot.

[0006] Preferably, a bushing is arranged around the iron core; the distance a from a side wall of the avoidance groove to the iron core is greater than the thickness of the bushing; and the bushing extends into the first air gap and is spaced apart from the side wall of the avoidance groove.

[0007] Preferably, the outer magnetic yoke is provided with an outer bending foot that is bent in the direction of the iron core and the outer bending foot is opposite to the inner bending foot; an armature connected to the iron core is arranged between the outer bending foot and the inner bending foot; in an axial direction of the iron core, the distance D1 from the inner bending foot to the outer bending foot of the outer magnetic yoke minus the thickness D2 of the armature is greater than the distance a from the side wall of the avoidance groove to the iron core in a radial direction of the iron core.

[0008] Preferably, a side wall of the avoidance groove is an avoidance surface having an arc surface shape, and the distance from each position on the avoidance surface to the corresponding surface of the iron core is equal and is a.

[0009] Preferably, the outer magnetic yoke comprises a side plate and an outer bending foot; the permanent magnet is arranged between the side plate and the inner magnetic yoke; and in an axial direction of the iron core, the longest distance from the armature to the outer bending foot is b, and the longest distance from the armature to the inner bending foot is c, where b=c>a.

[0010] Preferably, in an axial direction of the iron core, the minimum distance from the armature to the side plate is d, where d>b=c; and the length of one end of the armature in contact with the outer bending foot is less than or equal to 6 mm.

[0011] Preferably, wherein when the coil is powered on, the permanent magnetic generates a first powered-on electromagnetic circuit, a second powered-on electromagnetic circuit and a third powered-on electromagnetic circuit, respectively; the first powered-on electromagnetic circuit passes through the permanent magnet, the outer magnetic yokes, the iron core, the first air gap and the inner magnetic yokes in sequence and then returns to the permanent magnet; the second powered-on electromagnetic circuit passes through the permanent magnet, the outer magnetic yokes, the armature, the moving iron core and the inner magnetic yokes in sequence and then returns to the permanent magnet; and the third powered-on electromagnetic circuit passes through the outer magnetic yokes, the iron core, the armature and the outer magnetic yokes in sequence.

[0012] Preferably, a second magnetic conductor is arranged at one end of the iron core away from the first air gap, and a sleeve is arranged between the second magnetic conductor and the iron core.

[0013] Preferably, comprising two outer magnetic yokes and two inner magnetic yokes, wherein the two outer magnetic yokes are arranged oppositely; the two inner magnetic yokes are opposite to each other and located between the two outer magnetic yokes; each outer magnetic yoke comprises a side plate; an upper bending foot and an outer bending foot are respectively arranged at two ends of the side plate; the permanent magnet is arranged between the side plate and the inner magnetic yoke; the outer bending foot is opposite to the inner bending foot; the armature is arranged between the outer bending foot and the inner bending foot; one side of the armature is connected to one end of the iron core; a partition plate is arranged on one side of the armature away from the iron core; a supporting plate is arranged on one side of the partition plate away from the armature; and the supporting plate, the partition plate and the armature are connected to the iron core through screws or rivets.

[0014] Preferably, the coil is mounted on the coil skeleton; the coil skeleton comprises a cylinder, as well as a base and a cover plate that are respectively formed integrally at two ends of the cylinder; the iron core is arranged on the inner side of the cylinder; the coil is mounted on the outer side of the cylinder and is located between the base and the cover plate; the base is respectively provided with an inner mounting groove and an outer mounting groove; and the inner mounting groove and the outer mounting groove are respectively in limiting fit with the inner magnetic yoke and the outer magnetic yoke.

[0015] According to the electromagnetic mechanism of the present invention, the inner bending foot of the inner magnetic yoke is provided with the avoidance groove for avoiding the iron core, such that the first air gap is formed between side walls of the avoidance groove around the iron core, and a new magnetic circuit is formed outside the inner magnetic yoke through the first air gap. The new magnetic circuit is then attracted by the permanent magnet, which can not only ensure the attraction and release characteristics, but also eliminate the need to use a gasket, thereby avoiding the problems of increased assembly difficulty, size-control difficulty and large assembly errors caused by the gasket.

[0016] Furthermore, the first air gap can make a main magnetic circuit not extend directly from the iron core to the inner magnetic yoke, but must pass through the armature, so that the permanent magnet produces an upward attraction force to the armature, thereby ensuring an upward force of the iron core and also ensuring reliable resetting.BRIEF DESCRIPTION OF THE DRAWINGS

[0017] FIG. 1 is an exploded view of an electromagnetic mechanism in the present invention; FIG. 2 is a schematic structural diagram of an inner electromagnetic yoke 13 in the present invention; FIG. 3 is a schematic diagram of the cooperation between the inner magnetic yoke 13 and an iron core 16 in the present invention; FIG. 4 is a sectional view when the electromagnetic mechanism is powered off in the present invention; FIG. 5 is a sectional view when the electromagnetic mechanism is powered on in the present invention; FIG. 6 is a schematic structural diagram of an outer electromagnetic yoke 11 in the present invention; FIG. 7 is another schematic structural diagram of the inner electromagnetic yoke 13 in the present invention; FIG. 8 is another sectional view of the electromagnetic mechanism in the present invention; FIG. 9 is a schematic structural diagram of a coil skeleton 15 in the present invention; and FIG. 10 is sectional view of the coil skeleton 15 in the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0018] The specific implementation of an electromagnetic mechanism of the present invention will be further described below with reference to the embodiments given in the accompanying diagrams. The electromagnetic system of the present invention is not limited to the description of the following embodiments.

[0019] As shown in FIGs. 1-3, the electromagnetic mechanism of the present invention includes a coil 14, an iron core 16 arranged in the coil 14, an outer magnetic yoke 11 and an inner magnetic yoke 13, wherein the inner magnetic yoke 13 is located between the coil 14 and the outer magnetic yoke 11; a permanent magnet 12 is arranged on the inner magnetic yoke 13; an inner bending foot 131 that is bent in a direction of the iron core 16 is arranged on a side of the inner magnetic yoke 13 close to the iron core 16; the inner bending foot 131 is provided with an avoidance groove 132 for avoiding the iron core 16; and a first air gap 100 is formed between the periphery of the iron core 16 and a side wall of the avoidance groove 132.

[0020] According to the electromagnetic mechanism of the present invention, the inner bending foot 131 of the inner magnetic yoke 13 is provided with the avoidance groove 132 for avoiding the iron core 16, such that the first air gap 100 is formed between side walls of the avoidance groove 132 around the iron core 16, and a new magnetic circuit is formed outside the inner magnetic yoke through the first air gap 100. The new magnetic circuit is then attracted by the permanent magnet 12, which can not only ensure the attraction and release characteristics, but also eliminate the need to use a gasket, thereby avoiding the problems of increased assembly difficulty, size-control difficulty and large assembly errors caused by the gasket.

[0021] As shown in FIGs. 1-3, the electromagnetic mechanism in this embodiment includes two outer magnetic yokes 11 and two inner magnetic yokes 13, wherein the two outer magnetic yokes 11 are arranged oppositely, and the two inner magnetic yokes 13 are arranged oppositely between the two outer magnetic yokes 11. The permanent magnet 12 is arranged on each of the two inner magnetic yokes 13. The permanent magnet 12 is located between each outer magnetic yoke 11 and the corresponding inner magnetic yoke 13. The coil 14 is arranged between the two inner magnetic yokes 13. The iron core is arranged on the inner side of the coil 14. The inner bending foot 131 is arranged on a side of each of the two inner magnetic yokes 12 close to the iron core 16 in a bending manner. A plane where the inner bending foot 131 is located is perpendicular to an axial direction of the iron core 16. The inner bending foot 131 is provided with the avoidance groove 132 for avoiding the iron core 16. The first air gap in contact with the inner magnetic yoke 13 is formed around the iron core 16. The avoidance groove 132 is semicircular. The two inner bending feet 131 are spaced apart from each other. The two avoidance grooves 132 form an approximately circular hole around the surface at one end of the iron core 16. A side wall of each avoidance groove 132 is an avoidance surface having an arc surface shape.

[0022] As shown in FIGs. 1-3, a bushing 8 is arranged around the iron core 16. The distance a from the side wall of the avoidance groove 132 to the iron core 16 is greater than the thickness of the bushing 8. The bushing 8 can extend into the first air gap 100 and is spaced apart from the side wall of the avoidance groove 132.

[0023] As shown in FIG. 3, preferably, the avoidance groove 132 is provided with the avoidance surface having the arc surface shape, and the distance from each position on the avoidance surface to an axis of the iron core 16 is equal. That is, in a direction of the plane where the inner bending foot 131 is located, the distance from each position on the avoidance surface to the corresponding surface of the iron core 16 is equal and is a.

[0024] Further, an armature 7 connected to the iron core 16 is arranged between the outer magnetic yoke 11 and the inner bending foot 131. The outer magnetic yoke 11 is provided with an outer bending foot 111 that is bent in the direction of the iron core 16. The outer bending foot 111 is opposite to the inner bending foot 131. The armature 7 connected to the iron core 16 is arranged between the outer bending foot 111 and the inner bending foot 131. A second air gap is formed between the outer bending foot 111 and the inner bending foot 131. The distance D1 from the inner bending foot 131 to the outer bending foot 111 in an axial direction of the iron core 16 (i.e., a movement direction of the iron core 16) minus the thickness D2 of the armature 7 is greater than the distance a from the avoidance groove 132 to the iron core 16 in a radial direction of the iron core 16, that is, D1-D2>a.

[0025] Since the magnitude of the electromagnetic force is determined by the magnitude of a magnetic flux density at an air gap on the surface of the armature 7 and the direction points to a direction of the reduction of the air gap, the direction of the electromagnetic force points to the direction of the reduction of the air gap that produces a maximum electromagnetic force. The first air gap 100 can make a main magnetic circuit not extend directly from the iron core 16 to the inner magnetic yoke 13, but must pass through the armature 7, so that the permanent magnet 12 produces an upward attraction force to the armature 7, thereby ensuring an upward force of the iron core 16 and also ensuring reliable resetting.

[0026] Specifically, the outer magnetic yoke 11 includes a side plate 113. The upper bending foot 112 and the outer bending foot 111 are respectively arranged at two ends of the side plate 113. Two inner magnetic yokes 13 are arranged on the inner sides of the two side plates 113. The two side plates 113 are respectively opposite to the two inner magnetic yokes 13 each other. The permanent magnet 12 is arranged between each side plate 113 and the corresponding inner magnetic yoke 13. The outer bending feet 111 are respectively opposite to the two inner bending feet 131. The armature 7 is arranged between the outer bending feet 111 and the inner bending feet 131. The distance from the inner bending foot 131 to the outer bending foot 111 is D1.

[0027] The second air gap includes an upper air gap and a lower air gap respectively located at two sides of the armature 7. That is, in an axial direction of the iron core 16, the upper air gap is located between the armature 7 and the inner bending foot 131, and the lower air gap is located between the armature 7 and the outer bending foot 111 of the outer magnetic yoke 11. The sizes of the upper air gap and the lower air gap change with the movement of the armature 7. When the armature 7 is in contact with the inner bending foot 131, the distance between the armature 7 and the outer bending foot 111 is longest, i.e., b; and when the armature 7 is in contact with the outer bending foot 111, the distance between the armature 7 and the inner bending foot 131 is longest, i.e., c, where b=c>a.

[0028] A magnetic force produced by the coil 14 in a product attraction process is downward, and a force generated by the permanent magnet 12 at the beginning is kept in a disconnected state. With the increase of the attraction force of the coil 14 and the change of a downward stroke, the air gap changes accordingly. The direction of the magnetic force always points to the direction of the reduction of the air gap, the magnetic force of the permanent magnet 12 will change after reaching an equilibrium point of the air gap. The coil 14 and the permanent magnet 12 act together when reaching a closed state, in order to keep in a connected state.

[0029] As shown in FIG. 5, in the radial direction of the iron core 16, minimum distances between two ends of the armature 7 and the two side plates 113 of the outer magnetic yoke 11 are d, respectively, where the d>b=c. The lengths of the side surface of the armature 7 in contact with the two outer bending feet 111 of the outer magnetic yokes 11 are e, respectively. That is, the length of any end of the armature 7 in contact with the outer bending foot 111 is e, where e ≤6 mm.

[0030] As shown in FIG. 4, the coil 14 has no current after being powered off, and thus does not produce a magnetic force. The iron core 16 and the armature 7 move upward under a reaction force of a spring 1, the armature 7 is in contact with the inner bending foot 131, and only a first powered-off electromagnetic circuit 101 and a second powered-off electromagnetic circuit 102 are shown at this moment when the permanent magnet 12 is excited: the first powered-off electromagnetic circuit 101 passes through the permanent magnet 12, the outer magnetic yokes 11, the iron core 16, the armature 7 and the inner magnetic yokes 13 in sequence and then returns to the permanent magnet 12, and the first powered-off electromagnetic circuit 101 is a path through which a main magnetic flux flows; and the second powered-off electromagnetic circuit 102 passes through the permanent magnet 12, the outer magnetic yokes 11, the second air gap and the inner magnetic yokes 13 in sequence and then returns to the permanent magnet 12, and the second powered-off electromagnetic circuit 102 is a path through which a leakage magnetic flux flows, which has a smaller magnetic force relative to the main magnetic circuit.

[0031] As shown in FIG. 5, after the coil 14 is powered on to overcome a force of the spring 1 and a magnetic force produced by the permanent magnet 12, the iron core 16 and the armature 7 move downward to push the outer magnetic yoke 11. In the process of pushing the outer magnetic yoke 11, the air gap changes from large to small in a downward direction. The direction of the magnetic force of the permanent magnet 12 points to the direction of the reduction of the air gap. Under the joint action of the attraction force produced by the coil 14 and the magnetic force generated by the permanent magnet 12, the outer magnetic yoke 11 is pushed and holds, thereby completing an attraction operation.

[0032] As shown in FIG. 5, after the product attracts, the coil 14 is continuously powered on, the coil 14 produces a downward magnetic force to the armature 7, and the spring 1 is compressed and kept in a stable state of powered-on attraction. At the same time, the permanent magnet 12 is excited to produce three magnetic circuits, and also produces a downward force to the armature 7 so as to share the effect of the force of the coil 14, thereby saving the energy. The three magnetic circuits are respectively a first powered-on electromagnetic circuit 201, a second powered-on electromagnetic circuit 202 and a third powered-on electromagnetic circuit 203.

[0033] The first powered-on electromagnetic circuit 201 passes through the permanent magnet 12, the outer magnetic yokes 11, the iron core 16, the first air gap 100 and the inner magnetic yokes 13 in sequence and then returns to the permanent magnet 12.

[0034] The second powered-on electromagnetic circuit 202 passes through the permanent magnet 12, the outer magnetic yokes 11, the armature 7, the moving iron core 16 and the inner magnetic yokes 13 in sequence and then returns to the permanent magnet 12.

[0035] The third powered-on electromagnetic circuit 203 passes through the outer magnetic yokes 11, the iron core 16, the armature 7 and the outer magnetic yokes 11 in sequence.

[0036] The main magnetic circuit generated by the coil 14 plays a leading role in the third powered-on electromagnetic circuit 203 as shown in FIG. 5. The second powered-on electromagnetic circuit 202 has a leakage magnetic flux, which is the same as a magnetic flux path produced by the permanent magnet 12, both of which are opposite in direction and cancel out each other, without producing any additional influence. An effective part of the magnetic circuit generated by the permanent magnet 12 is the second powered-on magnetic circuit 202 of the magnetic circuit, and the magnetic circuit of the magnet circuit will be kept in a closed state to form a closed loop and plays a reinforcing effect on an attraction state.

[0037] The coil 14 is powered off after attraction, resets by the force generated by the spring 1, and then begins to act against the force generated by the permanent magnet 12. During the resetting process, the permanent magnet 12 changes from a resistance force to an attraction force with the change of the air gap, and acts together with the force generated by the spring 1, so that the armature 7 is pushed inward to the inner magnetic yoke 13, and then the product is released.

[0038] As shown in FIG. 1, the armature 7 is in the shape of a flat plate. The armature 7 is connected to the iron core 16 through a screw 3 or a rivet, rather than a high-temperature assembly mode, so that the assembly difficulty can be significantly reduced.

[0039] Further, a partition plate 5 is arranged at one side of the armature 7 away from the iron core 16. A supporting plate 4 is arranged at one side of the partition plate 5 away from the armature 7. The supporting plate 4, the partition plate 5 and the armature 7 are connected to the iron core 16 by means of screws 3 or rivets, and the screw 3 or rivets are connected to the iron core 16 after passing through the supporting plate 4, the partition plate 5 and the armature 7 in sequence, achieving the characteristic of convenient assembly. In addition, the partition plate 5 can adjust the force of the spring 1, and the supporting plate 4 can be used as a power source of the mechanism.

[0040] As shown in FIGs. 1, and 8-10, the coil skeleton 15 includes a cylinder 141, and a base 142 and a cover plate 143 that are integrally formed at two ends of the cylinder 141 respectively. A second spring 17 is arranged on the cover plate 143. The iron core 16 is arranged on the inner side of the cylinder 141. The coil 14 is mounted on the outer side of the cylinder 141 and is located between the base 142 and the cover plate 143. The iron core 16 can move vertically on the inner side of the cylinder 141. The coil skeleton 15 in this embodiment does not need to be assembled through two independent parts, and thus is more convenient to use.

[0041] Further, the base 142 is respectively provided with an inner mounting groove 154 and an outer mounting groove 155. The inner mounting groove 154 and the outer mounting groove 155 are respectively in limiting fit with the inner magnetic yoke 13 and the outer magnetic yoke 11. The inner magnetic yoke 13 and the outer magnetic yoke 11 are mounted on the base 142 through the inner mounting groove 154 and the outer mounting groove 155, achieving the advantages of stability and reliability.

[0042] According to a specific embodiment as shown in FIGs. 1-7, the electromagnetic mechanism in this embodiment includes an iron core 16, a coil skeleton 15 on which the iron core 16 is arranged and which is used to limit the iron core 16, a coil 14 wound on the coil skeleton 15, a support 2 supporting the coil skeleton 15, an armature 7 connected to the iron core 16, a spring 1 arranged between the armature 7 and the support 2, and a yoke assembly whose position corresponds to the armature 7 and the iron core 16 and which is fixed on the coil skeleton 15, wherein the spring 1 drives the armature 7 to move upward when the coil 14 is in a power-loss state.

[0043] The yoke assembly includes a pair of outer magnetic yokes 11 which are of the same shape corresponding to two sides of the iron core 16 in a state facing each other and all are C-shaped (or may also be U-shaped). A permanent magnet 12 and a pair of L-shaped inner magnetic yokes 13 are respectively arranged on the inner sides of the pair of outer magnetic yokes 11. A working space is formed between the pair of outer magnetic yokes 11. The iron core 16, the armature 7, the coil 14, the permanent magnet 12 and the inner magnetic yoke 13 are arranged in a cavity surrounded by the working space. The permanent magnet 12 is located between the inner magnetic yoke 13 and a lower position of a cavity wall of the outer magnetic yoke 11, and is limited by the inner magnetic yoke 13.

[0044] The iron core 16 is mounted in the coil skeleton 15, wherein the lower part of the iron core 16 is generally connected to the armature 7 by using a screw 3, a rivet or other means. The partition plate 5, the supporting plate 4 and the partition plate 5 are mounted below the armature 7 in sequence, and the armature 7 is fixed on the iron core 16 by means of the screw 3. The supporting plate 4 can be used as a power source to drive other mechanisms to act along with the iron core 16 (not shown). The size and structure of a head of the supporting plate 4 can be designed according to the needs, and the thickness is adjusted by changing the number of the partition plates 5, thereby adjusting a reaction force of the screw 3, as well as a position and stroke of the supporting plate 4 moving vertically.

[0045] The armature 7 is mounted between the outer bending feet 111 of a pair of outer magnetic yokes 11 and the inner bending feet 131 of a pair of inner magnetic yokes 13. When the coil 14 is released, it is reset by the action of the spring 1 and the permanent magnet 12, and is in contact with a pair of inner magnetic yokes 13. In the event that the coil 14 is attracted, the coil 14 is attracted onto the upper bending feet of a pair of the outer magnetic yokes 11 against the acting force of the spring 1, and kept stable under the attraction force of the coil 14 and the acting force of the permanent magnet 12. The length of the armature 7 in contact with the outer magnetic yoke 11 is e, and the smaller the magnitude of e, the greater the magnetic induction intensity, the greater the holding force, and the more reliable the product is in attraction.

[0046] The iron core 16, the armature 7, the pair of inner and outer magnetic yokes 11, and the pair of inner magnetic yokes 13 are all made of a magnetic permeable material, that is to say, the magnetic permeable material serves as the iron cores 16, the armature 7, the pair of inner and outer magnetic yokes 11, and the pair of inner magnetic yokes 13. In this embodiment, the magnetic permeable material is electrically pure iron or iron, or steel, or a silicon steel sheet can also be used.

[0047] A longitudinal cross-sectional shape of the iron core 16 is circular or square, and the iron core 16 is directly mounted in the coil skeleton 15 on which the coil 14 is well wound. The iron core 16 includes a lower column 161, a middle column 162 and an upper column 163, wherein the lower column 161 is smaller in size than the middle column 162, a bushing 8 is mounted outside the lower column 161. The bushing 8 is made of a plastic material such as PBT, which is used for changing the magnetic permeability and reducing the number of magnetic lines passing through. The upper column 163 of the iron core 16 is used for being connected to a mechanism that moves under the drive of the iron core (not shown). The mechanism drives other parts or contacts to act, such as a contact support similar to a contactor. A screw or a clamping groove bayonet structure is adopted to be connected to the iron core. The iron core acts to drive the action of a part connected thereto, and this part drives the movement of other parts or the movement of part contacts mounted on the part, thereby achieving a movement function or the connection and disconnection of the contacts. The upper column 163 of the iron core 16 is generally provided with a threaded hole, a V-shaped or I-shaped groove or other structures, so as to facilitate connection and installation. The upper end of the spring 1 is supported on the armature 7 or the partition plate 5 below the armature 7, and the lower end of the spring 1 is supported on the support 2. The support 2 is assembled together with the coil skeleton 15 in the form of a buckle. Of course, it is also feasible to adopt the structure of the screw 3. A pair of buffering members 6 are placed between the outer magnetic yoke 11 and the support 2, and generate a pre-compression force on the support 2, thereby ensuring the stability of the position of the support 2, ensuring that the position of the spring 1 does not change, and improving the stability of the spring 1.

[0048] As shown in FIG. 1, a pair of C-shaped outer magnetic yokes 11 is provided. The upper bending foot 112 at the upper part has a length greater than that of the outer bending foot at the lower part. The upper bending foot 112 and the outer bending foot 111 are respectively mounted in the corresponding grooves of the coil skeleton 15. The upper bending foot 112 is provided with a concave groove, which has a shape consistent with that of the middle column 162 and has a size that maintains a fit clearance with the middle column 162 for reliable movement, so as to ensure that the vertical movement of the iron core 16 is flexible and reliable. The outer bending foot 111 at the lower part is smaller in size, and forms a magnetic loop with the armature 7 in a closed state.

[0049] A pair of inner magnetic yokes 13, which is the biggest difference from conventional magnets in that the inner bending feet 131 form a new magnetic loop. Each inner bending foot 131 is provided with a concave avoidance groove 132; the avoidance groove 132 is provided with an avoidance surface corresponding to the shape of the lower column 161, and a first air gap 100 with a constant distance a is formed. A boss, an upper limiting boss 135, a lower limiting boss 133, and left and right limiting bosses 134 are stamped out on a longitudinal plane of the inner magnetic yoke 13, and used for mounting limit of the permanent magnet 12.

[0050] A second specific implementation is shown in FIG. 8. In FIG. 6, based on FIG. 2, a second magnetic conductor 18 is additionally arranged at one end of the iron core 16 away from the first air gap 100, and a sleeve 19 is arranged between the second magnetic conductor 18 and the iron core 16. The structure of the coil skeleton 15 as well as a transverse shape and structure above the outer magnetic yoke 11 are adjusted accordingly, so that an air gap among the outer magnetic yoke 11, the magnetic conductor 18 and the iron core 16 is as small as possible under the condition of ensuring flexible movement. The magnetic conductor 18 is made of a magnetic material. A longitudinal contact direction with the iron core 16 is increased by using the magnetic conductor, and the stability of the magnetic circuit is improved.

[0051] As shown in FIGs. 9-10, a through hole 151 is formed in the middle of the coil skeleton 15, and the iron core 16 is capable of moving freely in the through hole 151. The coil skeleton 15 has two sections of different thicknesses in the middle, wherein the thick section may accommodate the magnetic conductor 18 inside. A mounting groove is designed above and below the coil skeleton respectively so as to mount the outer magnetic yoke 11 and the magnetic yoke 13. The upper bending foot 112 above the outer magnetic yoke 11 is mounted in the groove 153 above the coil skeleton 15, the outer bending foot 111 below the outer magnetic yoke 11 is mounted in the outer mounting groove 155, and the inner bending foot 131 of the magnetic yoke 13 is mounted in the inner mounting groove 154, thereby achieving limiting, positioning and fixation of the magnetic yokes. A lower boss 156 is mounted on the support 2.

[0052] It should be explained that, in the description of the present invention, the terms such as "up", "down", "left", "right", "inner" and "outer" indicating the directional or positional relations on the basis of the directional or positional relations shown in the drawings are only used for conveniently describing the present invention and simplifying the description, not indicate or imply that the referred devices or elements must have a specific orientation and be configured and operated in a specific direction; therefore, they cannot be construed as a limitation on the present invention.

[0053] We have made further detailed description of the present invention mentioned above in combination with specific preferred embodiments, but it is not deemed that the specific embodiments of the present invention is only limited to these descriptions. A person skilled in the art can also, without departing from the concept of the present invention, make several simple deductions or substitutions, which all be deemed to fall within the protection scope of the present invention.

Claims

1. An electromagnetic mechanism, comprising a coil (14), an iron core (16) arranged in the coil (14), an outer magnetic yoke (11) and an inner magnetic yoke (13), wherein the inner magnetic yoke (13) is located between the coil (14) and the outer magnetic yoke (11); a permanent magnet (12) is arranged on the inner magnetic yoke (13); an inner bending foot (131) that is bent in a direction of the iron core (16) is arranged on a side of the inner magnetic yoke (13) close to the iron core (16); the inner bending foot (131) is provided with an avoidance groove (132) for avoiding the iron core (16); and a first air gap (100) is formed between the periphery of the iron core (16) and the inner bending foot (131).

2. The electromagnetic mechanism according to claim 1, wherein a bushing (8) is arranged around the iron core (16); the distance a from a side wall of the avoidance groove (132) to the iron core (16) is greater than the thickness of the bushing (8); and the bushing (8) extends into the first air gap (100) and is spaced apart from the side wall of the avoidance groove (132).

3. The electromagnetic mechanism according to claim 1, wherein the outer magnetic yoke (11) is provided with an outer bending foot (111) that is bent in the direction of the iron core (16) and the outer bending foot (111) is opposite to the inner bending foot (131); an armature (7) connected to the iron core (16) is arranged between the outer bending foot (111) and the inner bending foot (131); in an axial direction of the iron core (16), the distance D1 from the inner bending foot (131) to the outer bending foot (111) of the outer magnetic yoke (11) minus the thickness D2 of the armature (7) is greater than the distance a from the side wall of the avoidance groove (132) to the iron core (16) in a radial direction of the iron core (16).

4. The electromagnetic mechanism according to claim 3, wherein a side wall of the avoidance groove (132) is an avoidance surface having an arc surface shape, and the distance from each position on the avoidance surface to the corresponding surface of the iron core (16) is equal and is a.

5. The electromagnetic mechanism according to claim 3, wherein the outer magnetic yoke (11) comprises a side plate (113) and an outer bending foot (111); the permanent magnet (12) is arranged between the side plate (113) and the inner magnetic yoke (13); and in an axial direction of the iron core (16), the longest distance from the armature (7) to the outer bending foot (111) is b, and the longest distance from the armature (7) to the inner bending foot (131) is c, where b=c>a.

6. The electromagnetic mechanism according to claim 5, wherein in an axial direction of the iron core (16), the minimum distance from the armature (7) to the side plate (113) is d, where d>b=c; and the length of one end of the armature (7) in contact with the outer bending foot (111) is less than or equal to 6 mm.

7. The electromagnetic mechanism according to claim 1, wherein when the coil (14) is powered on, the permanent magnetic (12) generates a first powered-on electromagnetic circuit (201), a second powered-on electromagnetic circuit (202) and a third powered-on electromagnetic circuit (203), respectively; the first powered-on electromagnetic circuit (201) passes through the permanent magnet (12), the outer magnetic yokes (11), the iron core (16), the first air gap (100) and the inner magnetic yokes (13) in sequence and then returns to the permanent magnet (12); the second powered-on electromagnetic circuit (202) passes through the permanent magnet (12), the outer magnetic yokes (11), the armature (7), the moving iron core (16) and the inner magnetic yokes (13) in sequence and then returns to the permanent magnet (12); and the third powered-on electromagnetic circuit (203) passes through the outer magnetic yokes (11), the iron core (16), the armature (7) and the outer magnetic yokes (11) in sequence.

8. The electromagnetic mechanism according to claim 1, wherein a second magnetic conductor (18) is arranged at one end of the iron core (16) away from the first air gap (100), and a sleeve (19) is arranged between the second magnetic conductor (18) and the iron core (16).

9. The electromagnetic mechanism according to claim 1, comprising two outer magnetic yokes (11) and two inner magnetic yokes (13), wherein the two outer magnetic yokes (11) are arranged oppositely; the two inner magnetic yokes (13) are opposite to each other and located between the two outer magnetic yokes (11); each outer magnetic yoke (11) comprises a side plate (113); an upper bending foot (112) and an outer bending foot (111) are respectively arranged at two ends of the side plate (113); the permanent magnet (12) is arranged between the side plate (113) and the inner magnetic yoke (13); the outer bending foot (111) is opposite to the inner bending foot (131); the armature (7) is arranged between the outer bending foot (111) and the inner bending foot (131); one side of the armature (7) is connected to one end of the iron core (16); a partition plate (5) is arranged on one side of the armature (7) away from the iron core (16); a supporting plate (4) is arranged on one side of the partition plate (5) away from the armature (7); and the supporting plate (4), the partition plate (5) and the armature (7) are connected to the iron core (16) through screws (3) or rivets.

10. The electromagnetic mechanism according to claim 1, wherein the coil (14) is mounted on the coil skeleton (15); the coil skeleton (15) comprises a cylinder (141), as well as a base (142) and a cover plate (143) that are respectively formed integrally at two ends of the cylinder (141); the iron core (16) is arranged on the inner side of the cylinder (141); the coil (14) is mounted on the outer side of the cylinder (141) and is located between the base (142) and the cover plate (143); the base (142) is respectively provided with an inner mounting groove (154) and an outer mounting groove (155); and the inner mounting groove (154) and the outer mounting groove (155) are respectively in limiting fit with the inner magnetic yoke (13) and the outer magnetic yoke (11).

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