A door magnetic switch for household appliances

Abstract

The invention discloses a household appliance door magnetic switch, comprising an electromagnet assembly and a permanent magnet that interact with each other, the electromagnet assembly comprising an electromagnetic coil and a metal core, the metal core being fixed inside the electromagnetic coil; the electromagnetic coil is electrically connected to a drive circuit, a rectifier bridge stack for converting the alternating current input into the electromagnetic coil into direct current is arranged on the drive circuit, the electromagnet body has a first mating end face that interacts with the permanent magnet, the permanent magnet has a second mating end face that interacts with the electromagnet body, the two mating end faces are arranged facing each other and in corresponding positions, when the electromagnetic coil is energized, the magnetic polarity of the first mating end face is the same as the magnetic polarity of the second mating end face, a repulsive force is generated between the electromagnet body and the permanent magnet, when the electromagnetic coil is powered off, the magnetism of the electromagnet body disappears, and an attractive force is generated between the metal core and the permanent magnet. The door magnetic switch disclosed by the invention pushes the appliance door open by magnetic force, the thrust is stable and reliable, no noise is generated, and the service life is long.

Description

Technical Field

[0001] The invention belongs to the technical field of household appliances, and in particular relates to a door magnetic switch for household appliances. Background Art

[0002] In order to facilitate user use and achieve automation, existing household appliances usually use mechanical switches to open and close their doors or windows, and also use electromagnetic effects to control the appliance doors, so that the doors of household appliances can be opened without relying on manual operation. However, existing door magnetic switches mostly use electromagnets to control the movement of a push rod to push the appliance door. This type of door magnetic switch has the following disadvantages: the push rod must be in contact with the appliance door to push the door open, and in order to overcome the locking force, the electromagnet needs to apply sufficient thrust to the push rod. Therefore, a lot of noise is generated when the push rod hits the appliance door, and frequent collisions can also cause damage to the appliance door; in order to cooperate with the movement of the push rod, a sufficiently large installation space needs to be provided for the door magnetic switch, which affects the compactness of the appliance structure; the push rod is in a movable state, and its installation stability and movement reliability are not high, resulting in a short service life of the door magnetic switch. Summary of the invention

[0003] In order to solve the above technical problems, the present invention provides a door magnetic switch for household appliances.

[0004] The object of the present invention is achieved through the following technical solutions:

[0005] A household appliance door magnetic switch comprises an electromagnet assembly and a permanent magnet that interact with each other. The electromagnet assembly comprises an electromagnet body and a drive circuit. The electromagnet body comprises an electromagnetic coil and a metal core that can be magnetized by the magnetic field of the electromagnetic coil, and the metal core is fixed inside the electromagnetic coil. The electromagnetic coil is electrically connected to the drive circuit. The drive circuit is provided with a rectifier bridge stack that converts the alternating current input into the electromagnetic coil into direct current to keep the polarity of the electromagnetic coil fixed when energized. The electromagnet body has a first mating end face that interacts with the permanent magnet, and the permanent magnet has a second mating end face that interacts with the electromagnet body. The two mating end faces are arranged opposite to each other and have corresponding positions. When the electromagnetic coil is energized, the magnetic polarity of the first mating end face is the same as the magnetic polarity of the second mating end face, and a repulsive force is generated between the electromagnet body and the permanent magnet. When the electromagnetic coil is powered off, the magnetism of the electromagnet body disappears, and an attractive force is generated between the metal core and the permanent magnet. In the present technical scheme, the polarity of the electromagnet body can be fixed by setting a rectifier bridge stack to meet the coordination requirements between the electromagnet and the permanent magnet. Compared with the mechanically moved push rod, the magnetic force is more stable and reliable, has a longer service life, and will not cause damage to the appliance door. A metal core is built into the electromagnetic coil. When the appliance door needs to be opened, the electromagnetic coil is energized, and the metal core is magnetized by the magnetic field of the electromagnetic coil. The magnetized iron core also becomes a magnet. In this way, since the magnetic poles of the two mating end faces are consistent, they repel each other, so that the permanent magnet drives the appliance door to move backward to open the appliance door. When the electromagnetic coil is powered off, the magnetism of the metal core will disappear, and an attraction will be generated between it and the permanent magnet. When the appliance door needs to be closed, the permanent magnet on the appliance door will be attracted to the metal core.

[0006] Preferably, the drive circuit is provided with a PTC resistor, which is connected in series between the power input terminal and the rectifier bridge stack. The PTC resistor can prevent the electromagnetic coil from heating up due to long-term power-on, causing excessive temperature rise, so as to stabilize the performance of the door magnetic switch.

[0007] Preferably, the electromagnetic coil is wound on a coil frame, and the coil frame includes two oppositely disposed outer end walls and an inner end wall, and a coil column is disposed between the outer end wall and the inner end wall, and the coil column is a hollow cylinder, and the electromagnetic coil is wound on the outer circumferential surface of the coil column. By setting the coil frame, the structure of the electromagnet body can be made more stable, the coil column core is cylindrical, and the electromagnetic coil wound thereon is also cylindrical, which can make the electromagnetic coil generate an aligned magnetic field along the axial direction, so that the thrust on the appliance door is more stable and reliable.

[0008] Preferably, the metal core comprises a cylindrical main body and a stopper located at the rear end of the main body, the main body is tightly embedded in the coil column and is coaxially arranged with the coil column. The coaxial arrangement of the metal core and the coil column can enhance the magnetic field of the electromagnet body and make the structure of the electromagnet body more compact.

[0009] Preferably, the limiting portion includes a limiting boss and a connecting column between the limiting boss and the main body, the limiting boss, the connecting column and the main body are coaxially arranged, the outer diameter of the limiting boss is smaller than the outer diameter of the main body, but larger than the outer diameter of the connecting column. The limiting portion is arranged to ensure the installation stability of the metal core and prevent it from moving forward and backward along the axial direction under the action of the magnetic force.

[0010] Preferably, one end of the coil column close to the inner end wall is a limiting end, and the inner wall of the limiting end is provided with a limiting ridge along the circumferential direction, and when the metal core is embedded in the coil column, the rear end face of the main body thereof abuts against the limiting ridge. When the electromagnet and the permanent magnet generate a repulsive force, the limiting ridge cooperates with the limiting part of the metal core to effectively prevent the metal core from moving backward along the axial direction.

[0011] Preferably, the limiting end of the coil column is buckled with an end cap, the limiting portion of the metal core is limited in the end cap, and a clamping hole matching the limiting ridge is opened along the circumferential direction on the outer peripheral surface of the annular side wall of the end cap. The limiting ridge is clamped in the clamping hole, which can further improve the installation stability of the metal core.

[0012] Preferably, the annular side wall of the end cover includes a reduced diameter section and an expanded diameter end, the inner diameter of the reduced diameter end matches the outer diameter of the connecting column, the inner diameter of the expanded diameter end matches the outer diameter of the limiting boss, the connecting column is limited at the reduced diameter end, and the limiting boss is limited at the expanded diameter end. When the permanent magnet generates an attractive force on the metal core, the cooperation between the limiting portion of the metal core and the end cover and the limiting convex ridge can effectively prevent the metal core from moving forward in the axial direction and being pulled out by the permanent magnet.

[0013] Preferably, the central axis of the metal core is perpendicular to the first mating end face. This arrangement can make the interaction force between the electromagnet body and the permanent magnet more reliable and effective.

[0014] Preferably, the first mating end face of the electromagnet body is flush with the outer end wall of the coil frame. The above arrangement can make the contact and mating between the electromagnet body and the permanent magnet more reliable.

[0015] Preferably, the metal core is made of soft iron or silicon steel. Using soft iron or silicon steel as the metal core can make the metal core demagnetized immediately after the electromagnetic coil is powered off, ensuring that the permanent magnet can be adsorbed on the metal core.

[0016] Preferably, under rated voltage, the magnetic field strength of the electromagnet body at a position 0.5 mm away from the center surface of the metal core is ≥180 mT.

[0017] Preferably, the magnetic field strength of the second mating end face of the permanent magnet is ≥400mT.

[0018] Preferably, the electromagnetic thrust of the electromagnet body on the permanent magnet is ≥45N under rated voltage.

[0019] Preferably, the polarity of the first mating end face of the electromagnet body is an N pole, and the polarity of the second mating end face of the permanent magnet is also an N pole.

[0020] Compared with the prior art, the present invention has the following beneficial effects: the door magnetic switch disclosed in the present invention pushes open the appliance door through magnetic force, which is more stable and reliable than the thrust applied by the push rod, does not generate noise, and has a long service life; the metal core is fixed in the electromagnetic coil, and there is no need to provide displacement space for it, so that the structure of the entire door magnetic switch is more compact and saves installation space; by improving the metal core and the coil frame structure, and cooperating with the end cover, the installation stability of the metal core can be guaranteed, and it is prevented from moving axially under the action of magnetic force, thereby further improving the reliability of the door magnetic switch. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] Figure 1 It is a schematic diagram of the structure of the present invention;

[0022] Figure 2 It is a schematic diagram of the structure of the electromagnet assembly in the present invention;

[0023] Figure 3 It is a schematic diagram of the internal structure of the electromagnet assembly in the present invention;

[0024] Figure 4 Another schematic diagram of the internal structure of the electromagnet assembly in the present invention;

[0025] Figure 5 It is a schematic diagram of the structure of the driving circuit in the present invention;

[0026] Figure 6 It is a schematic diagram of the coil frame structure in the present invention;

[0027] Figure 7 It is a schematic diagram of the metal core structure in the present invention;

[0028] Figure 8 It is a schematic diagram of the end cover structure in the present invention;

[0029] Markings in the figure: 10 electromagnet assembly; 11 first mating end face; 12 housing; 13 metal core; 131 main body; 132 connecting portion; 133 limiting boss; 14 coil frame; 141 coil column; 142 outer end wall; 143 inner end wall; 144 limiting convex ridge; 15 rectifier bridge stack; 16 PTC resistor; 17 electromagnetic coil; 18 end cover; 181 clamping hole; 20 permanent magnet. DETAILED DESCRIPTION

[0030] The present invention will be further described below with reference to the embodiments shown in the accompanying drawings:

[0031] Example 1, see Figure 1-8The present embodiment discloses a household appliance door magnetic switch, comprising an electromagnet assembly 10 and a permanent magnet that interact with each other and are separately arranged, which is applied to a drum washing machine, wherein the electromagnet assembly 10 is installed behind the front wall of the washing machine body, and the permanent magnet is integrated in the washing machine door; the electromagnet assembly 10 comprises an electromagnet body and a drive circuit, the electromagnet body comprises an electromagnetic coil 17 and a metal core 13 that can be magnetized by the magnetic field of the electromagnetic coil 17, and the metal core 13 is fixed inside the electromagnetic coil 17; the electromagnetic coil 17 is electrically connected to the drive circuit, and a rectifier bridge stack 15 is provided on the drive circuit to convert the alternating current input to the electromagnetic coil 17 into direct current to keep the polarity of the electromagnetic coil 17 fixed when the power is on. By setting the rectifier bridge stack 15, the polarity of the electromagnet body can be fixed to meet the matching requirements between it and the permanent magnet. Compared with the push rod of mechanical movement, the magnetic force is more stable and reliable, the service life is longer, and it will not cause damage to the appliance door; the electromagnet body has a first matching end face 11 that interacts with the permanent magnet, and the permanent magnet has The second mating end face interacting with the electromagnet body, the two mating end faces are arranged opposite to each other and in corresponding positions. When the electromagnetic coil 17 is energized, the magnetic polarity of the first mating end face 11 is the same as the magnetic polarity of the second mating end face. In this embodiment, the magnetic polarities of the first mating end face 11 and the second mating end face are both N poles, and a repulsive force is generated between the electromagnet body and the permanent magnet. When the electromagnetic coil 17 is powered off, the magnetism of the electromagnet body disappears, and an attractive force is generated between the metal core 13 and the permanent magnet. The metal core 13 fixed in the electromagnetic coil 17 has two functions. When the appliance door needs to be opened, the electromagnetic coil 17 is energized, and the metal core 13 is magnetized by the magnetic field of the electromagnetic coil 17. The magnetized iron core also becomes a magnet. In this way, due to the superposition of the two magnetic fields, the magnetic field strength of the electromagnet body is enhanced, ensuring that it can provide sufficient thrust for the washing machine door to overcome the locking force to open the washing machine door. When the washing machine door is closed, the electromagnetic coil 17 is powered off, the magnetism of the metal core 13 disappears, and an attractive force is generated between it and the permanent magnet, thereby increasing the locking force of the washing machine door.

[0032] In addition to the rectifier bridge stack 15, the drive circuit is also provided with a PTC resistor 16, which is connected in series between the power input terminal and the rectifier bridge stack 15. The setting of the PTC resistor 16 can ensure that the electromagnetic coil 17 works at the rated current while preventing the electromagnetic coil 17 from heating up due to long-term power-on, causing excessive temperature rise, so as to stabilize the performance of the door magnetic switch.

[0033] The electromagnetic coil 17 is wound on the coil frame 14, and the coil frame 14 includes two oppositely arranged outer end walls 142 and an inner end wall 143. A coil column 141 is provided between the outer end wall 142 and the inner end wall 143. The coil column 141 is a hollow cylinder. The electromagnetic coil 17 is wound on the outer circumferential surface of the coil column 141. Through the arrangement of the coil frame 14, the structure of the electromagnet body can be made more stable. The core of the coil column 141 is cylindrical, and the electromagnetic coil 17 wound thereon is also cylindrical, which can enable the electromagnetic coil to generate an aligned magnetic field along the axial direction, so that the thrust of the electromagnetic coil on the appliance door is more stable and reliable.

[0034] In order to ensure the installation stability of the metal core 13 and prevent the metal core 13 from moving axially under the action of magnetic force, the metal core 13 includes a cylindrical main body 131 and a limiting portion located at the rear end of the main body 131. The main body 131 is tightly embedded in the coil column 141 and is coaxially arranged with the coil column 141; the limiting portion includes a limiting boss 133 and a connecting column 132 located between the limiting boss 133 and the main body 131. The limiting boss 133 is coaxially arranged with the connecting column 132 and the main body 131. The outer diameter of the positioning boss 133 is smaller than the outer diameter of the main body 131, but larger than the outer diameter of the connecting column 132. The setting of the limiting portion is to ensure the installation stability of the metal core 13 and prevent it from moving forward and backward along the axial direction under the action of the magnetic force; the end of the coil column 141 close to the inner end wall 143 is the limiting end, and the inner wall of the limiting end is circumferentially provided with a limiting ridge 144. When the metal core 13 is embedded in the coil column 141, the rear end face of the main body 131 thereof abuts against the limiting ridge 144, and a repulsive force is generated between the electromagnet body and the permanent magnet. When the metal core 13 is installed in the position-limiting ridge 144, the metal core 13 can be effectively prevented from moving backward in the axial direction. The limiting end of the coil column 141 is buckled with an end cover 18, and the limiting part of the metal core 13 is limited in the end cover 18. The outer peripheral surface of the annular side wall of the end cover 18 is provided with a clamping hole 181 matching the limiting ridge 144 in the circumferential direction. The limiting ridge 144 is clamped in the clamping hole 181, which can further improve the installation stability of the metal core 13. The annular side wall of the end cover 18 includes a reduced diameter section and an expanded diameter section. The inner diameter of the segment matches the outer diameter of the connecting column 132, the inner diameter of the expanded diameter segment matches the outer diameter of the limiting boss 133, the connecting column 132 is limited to the reduced diameter segment, and the limiting boss 133 is limited to the expanded diameter segment. The end cover 18 is later injection molded and can be closely matched with the limiting portion of the metal core 13 and the coil column 141. When the permanent magnet generates an attraction for the metal core 13, the cooperation between the limiting portion of the metal core 13 and the end cover 18 and the coil frame 14 can effectively prevent the metal core 13 from moving forward axially and being pulled out by the permanent magnet.

[0035] In order to demagnetize the metal core 13 immediately after the electromagnetic coil is powered off and ensure that the permanent magnet can be adsorbed on the metal core 13, the metal core 13 in this embodiment is made of soft iron; the central axis of the metal core 13 is perpendicular to the first matching end face 11 and also perpendicular to the front wall of the washing machine. This arrangement can make the interaction force between the electromagnet body and the permanent magnet more reliable and effective; in order to make the contact and matching between the electromagnet body and the permanent magnet more reliable, the first matching end face 11 of the electromagnet body is flush with the outer end wall 142 of the coil frame 14; the electromagnet body, the rectifier bridge stack 15, and the PTC resistor 16 are all sealed in the housing 12, and only the first matching end face 11 and the outer end wall 142 of the coil frame 14 are exposed from the housing 12 and are flush with the side wall of the housing 12.

[0036] The rated voltage of the electromagnetic coil 17 is AC 220V (±10%). Under the rated voltage, the magnetic field strength of the electromagnet body at a position 0.5mm away from the center surface of the metal core 13 is 200mT. In this embodiment, the permanent magnet material is neodymium iron boron, and its magnetic field strength at the second mating end face is 430mT. Under the rated voltage, the electromagnetic thrust of the electromagnet body on the permanent magnet is 60N, so that the washing machine door can overcome the lock and force to open.

[0037] The household appliance door magnetic switch disclosed in the present invention has a compact structure, a small size, a long service life, and a stable and reliable magnetic force. When the electromagnet body is energized, it can generate a repulsive force on the permanent magnet on the appliance door, thereby pushing the appliance door open. When the power is off, the magnetism of the metal core 13 disappears and can generate an attractive force on the permanent magnet on the appliance door, thereby enhancing the locking force of the appliance door. The metal core 13 has a dual function under the action of the magnetic force.

[0038] The specific embodiments described herein are merely examples of the spirit of the present invention. Those skilled in the art may make various modifications or additions to the specific embodiments described or replace them in similar ways, but they will not deviate from the spirit of the present invention or exceed the scope defined by the appended claims.

Claims

1. A door magnetic switch for household appliances, characterized in that: The invention comprises an electromagnet assembly (10) and a permanent magnet (20) that interact with each other. The electromagnet assembly (10) comprises an electromagnet body and a drive circuit. The electromagnet body comprises an electromagnetic coil (17) and a metal core (13) that can be magnetized by the magnetic field of the electromagnetic coil (17). The metal core (13) is fixedly arranged inside the electromagnetic coil (17). The electromagnetic coil (17) is electrically connected to the drive circuit. The drive circuit is provided with a rectifier bridge stack (15) that converts the alternating current input to the electromagnetic coil (17) into direct current to keep the polarity of the electromagnetic coil (17) fixed when power is supplied. The electromagnet body has a first mating end face (11) that interacts with the permanent magnet (20). The permanent magnet (20) has a second mating end face that interacts with the electromagnet body. The two mating end faces are arranged facing each other and in corresponding positions. When the electromagnetic coil (17) is energized, the magnetic polarity of the first mating end face (11) is the same as the magnetic polarity of the second mating end face, and a repulsive force is generated between the electromagnet body and the permanent magnet (20). When the electromagnetic coil (17) is de-energized, the magnetism of the electromagnetic body disappears, and an attractive force is generated between the metal core (13) and the permanent magnet (20). The electromagnetic coil (17) is wound on a coil frame (14), and the coil frame (14) includes two outer end walls (142) and an inner end wall (143) that are arranged opposite to each other. A coil column (141) is arranged between the outer end wall (142) and the inner end wall (143), and the coil column (141) is a hollow cylinder. The electromagnetic coil (17) is wound on the coil column (141). The metal core (13) comprises a cylindrical main body (131) and a limiting portion located at the rear end of the main body (131); the main body (131) is tightly embedded in the coil column (141) and is coaxially arranged with the coil column (141); the limiting portion comprises a limiting boss (133) and a connecting column (132) located between the limiting boss (133) and the main body (131); the limiting boss (133) is coaxially arranged with the connecting column (132) and the main body (131); the outer diameter of the limiting boss (133) is smaller than the outer diameter of the main body (131) but larger than the outer diameter of the connecting column (132); one end of the coil column (141) close to the inner end wall (143) is a limiting end, and the inner wall of the limiting end is arranged along the circumferential direction A limiting convex ridge (144) is provided, and when the metal core (13) is embedded in the coil column (141), the rear end surface of the main body (131) thereof abuts against the limiting convex ridge (144); an end cover (18) is buckled at the limiting end of the coil column (141), and the limiting part of the metal core (13) is limited in the end cover (18), and a clamping hole (181) matching the limiting convex ridge (144) is opened on the outer peripheral surface of the annular side wall of the end cover (18) along the circumferential direction; the annular side wall of the end cover (18) includes a reduced diameter section and an expanded diameter section, the inner diameter of the reduced diameter section matches the outer diameter of the connecting column (132), and the inner diameter of the expanded diameter section matches the outer diameter of the limiting boss (133), the connecting column (132) is limited in the reduced diameter section, and the limiting boss (133) is limited in the expanded diameter end;The drive circuit is provided with a PTC resistor (16), and the PTC resistor (16) is connected in series between the power input terminal and the rectifier bridge stack (15); the first matching end surface (11) of the electromagnet body is flush with the outer end wall (142) of the coil frame (14).

2. The household appliance door magnetic switch according to claim 1, characterized in that: The central axis of the metal core (13) is perpendicular to the first matching end surface (11).

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