Electromagnetic actuator

Abstract

The utility model relates to an electromagnetic actuator. The electromagnetic actuator comprises an electromagnetic field generator, a permanent magnet, an armature, a front magnetic pole and a rear magnetic pole, the front magnetic pole and the rear magnetic pole are located at the two axial ends of the electromagnetic field generator respectively, and the armature is installed on the radial inner side of the electromagnetic field generator. The armature can be driven by electromagnetic force of the electromagnetic field generator to axially move between a first limit position and a second limit position, the armature abuts against the front magnetic pole at the first limit position and abuts against the rear magnetic pole at the second limit position, and the front magnetic pole and the rear magnetic pole can be magnetized by the permanent magnet to generate magnetic attraction force for attracting the armature. The electromagnetic actuator further comprises a front elastic buffering piece and / or a rear elastic buffering piece, when the armature is located at the first limit position, the armature and the front magnetic pole compress the front elastic buffering piece in the axial direction, and when the armature is located at the second limit position, the armature and the rear magnetic pole compress the rear elastic buffering piece in the axial direction. The electromagnetic actuator provided by the utility model has an improved structure.

Description

Technical Field

[0001] This utility model relates to the field of actuator technology. Specifically, this utility model relates to an electromagnetic actuator with a buffer structure. Background Technology

[0002] An electromagnetic actuator is a component used to generate actuation force. In some applications, the armature of an electromagnetic actuator needs to remain in its extreme position at either end of the cavity (i.e., in the extended or retracted state) when not energized, while the armature's position is changed solely by the electromagnetic force generated when energized. This is typically achieved by using a permanent magnet to magnetize the front and rear poles, creating a magnetic attraction. Such electromagnetic actuators are commonly called bistable electromagnetic actuators. For example, with the development of drive-by-wire chassis and electromechanical braking (EMB) technology, some current EMB systems use bistable electromagnetic actuators to implement parking lock functions. When the vehicle is in normal driving, the electromagnetic actuator is in the retracted state; due to the presence of the permanent magnet, the armature and the rear pole remain in contact under the magnetic attraction. When parking brake is required, the electromagnetic actuator is energized, generating an additional electromagnetic force on the armature. Under the action of this electromagnetic force, the armature overcomes the magnetic attraction of the permanent magnet, detaches from the rear pole, and moves towards the front pole. When the armature comes into contact with the front pole, the power is turned off. Due to the presence of the permanent magnet, the armature and the front pole remain in contact under the magnetic attraction. When unlocking is required, a reverse current is introduced into the electromagnetic coil. The armature moves towards the rear pole under the action of a reverse electromagnetic force. After the power is turned off, the armature and the rear pole remain in contact under the magnetic attraction.

[0003] In existing technologies, when such electromagnetic actuators switch states, the armature strikes the front and rear magnetic poles, generating significant noise. This negatively impacts the user experience of the product. Utility Model Content

[0004] Therefore, the technical problem to be solved by this utility model is to provide an electromagnetic actuator that can reduce impact noise.

[0005] The above-mentioned technical problems are solved by an electromagnetic actuator according to the present invention. The electromagnetic actuator includes an electromagnetic field generator, a permanent magnet, an armature, a front magnetic pole, and a rear magnetic pole. The electromagnetic field generator and the permanent magnet are arranged coaxially. The front and rear magnetic poles are located at opposite ends of the axial direction of the electromagnetic field generator. The armature is mounted radially inside the electromagnetic field generator and can be driven by the electromagnetic force of the electromagnetic field generator to move axially relative to the electromagnetic field generator between a first limit position and a second limit position. The armature abuts against the front magnetic pole at the first limit position and against the rear magnetic pole at the second limit position. The front and rear magnetic poles can be magnetized by the permanent magnet to generate a magnetic attraction force that attracts the armature. The electromagnetic actuator also includes a front elastic buffer and / or a rear elastic buffer. The front elastic buffer is arranged between the armature and the front magnetic pole axially, such that when the armature is in the first limit position, the armature and the front magnetic pole compress the front elastic buffer axially. The rear elastic buffer is arranged between the armature and the rear magnetic pole axially, such that when the armature is in the second limit position, the armature and the rear magnetic pole compress the rear elastic buffer axially. When the armature moves to the point of contacting the front or rear magnetic pole, the corresponding elastic buffer between them is compressed, generating an elastic force that resists the opposing movement of the two poles. The elastic deformation of the two buffers at the moment of contact effectively buffers the impact force of the armature on the magnetic pole, thereby reducing impact noise.

[0006] According to a preferred embodiment of the present invention, the front elastic buffer can be positioned on one of the armature and the front magnetic pole, and / or the rear elastic buffer can be positioned on one of the armature and the rear magnetic pole. In particular, the elastic buffer can be radially constrained by either the armature or the magnetic pole.

[0007] According to another preferred embodiment of the present invention, the front elastic buffer and the rear elastic buffer can be formed as wave springs arranged around the axial direction. Wave springs have a small axial dimension, are easy to arrange in the cavity of the electromagnetic actuator, and can provide a large buffering force at the moment of contact.

[0008] According to another preferred embodiment of the present invention, the electromagnetic actuator may further include a push rod, which is fixed to the radially inner side of the armature and passes through the armature axially. A front elastic buffer and a rear elastic buffer can respectively surround the radially outer side of the push rod. This allows for convenient positioning of the two elastic buffers.

[0009] According to another preferred embodiment of the present invention, the push rod can constrain the front and / or rear elastic buffer members radially. The push rod can be clearance-fitted with the elastic buffer members, allowing the elastic buffer members to compress and deform axially while limiting significant radial movement of the elastic buffer members.

[0010] According to another preferred embodiment of the present invention, the front magnetic pole may include a front protrusion convex axially toward the armature, and the rear magnetic pole may include a rear protrusion convex axially toward the armature. The armature may include a front recess recessed axially from the axial end face toward the front magnetic pole and a rear recess recessed axially from the axial end face toward the rear magnetic pole. A push rod passes through the front and rear recesses respectively. A front elastic buffer may be installed in the front recess, and a rear elastic buffer may be installed in the rear recess. In a first extreme position, the front protrusion is inserted into the front recess, and the front elastic buffer is compressed between the front protrusion and the front recess. In a second extreme position, the rear protrusion is inserted into the rear recess, and the rear elastic buffer is compressed between the rear protrusion and the rear recess. The axial gap between the protrusion of the magnetic pole and the recess of the armature can accommodate the elastic buffer.

[0011] According to another preferred embodiment of the present invention, in the first extreme position, the armature can abut against the front magnetic pole through its axial end face facing the front magnetic pole, and in the second extreme position, the armature can abut against the rear magnetic pole through its axial end face facing the rear magnetic pole. This means that while compressing the elastic buffer, the armature can still directly abut against both magnetic poles.

[0012] According to another preferred embodiment of the present invention, the front recess can constrain the front elastic buffer member radially, and / or the rear recess can constrain the rear elastic buffer member radially. The inner wall of the recess can be clearance-fitted with the elastic buffer member, which on the one hand allows the elastic buffer member to compress and deform axially, and on the other hand restricts significant radial movement of the elastic buffer member.

[0013] According to another preferred embodiment of the present invention, the range of motion of the armature between the first and second extreme positions can be divided into a first end section, a second end section, and an intermediate section. The first end section is adjacent to the first extreme position, the second end section is adjacent to the second extreme position, and the intermediate section connects the first and second end sections. When the armature is located in the intermediate section, the front and rear elastic buffers are not compressed. This ensures that the armature only compresses the corresponding elastic buffers when it is about to contact the two magnetic poles, thus not affecting the movement of the armature. Attached Figure Description

[0014] The present invention will be further described below with reference to the accompanying drawings. In the drawings, the same reference numerals represent elements with the same function. Wherein:

[0015] Figure 1a and Figure 1b A longitudinal sectional view of an electromagnetic actuator according to an exemplary embodiment of the present invention is shown;

[0016] Figures 2a to 2c Schematic diagrams of the elastic buffer members of electromagnetic actuators according to different embodiments of the present invention are shown respectively;

[0017] Figure 3a and Figure 3b Schematic diagrams showing the installation methods of the elastic buffer member of the electromagnetic actuator according to different embodiments of the present invention; and

[0018] Figure 4a and Figure 4b The graph shows the magnetic attraction force and elastic force of an electromagnetic actuator according to an exemplary embodiment of the present invention. Detailed Implementation

[0019] The following describes specific embodiments of the electromagnetic actuator according to the present invention with reference to the accompanying drawings. The detailed description and drawings below are provided to exemplify the principles of the present invention. The present invention is not limited to the described preferred embodiments, and the scope of protection of the present invention is defined by the claims.

[0020] According to an embodiment of this utility model, an electromagnetic actuator is provided. This electromagnetic actuator is capable of maintaining the position of the armature without energization by magnetizing the front and rear magnetic poles with a permanent magnet, i.e., a bistable electromagnetic actuator.

[0021] Figure 1a and Figure 1b A longitudinal sectional view of an electromagnetic actuator according to an exemplary embodiment of the present invention is shown. As shown, the electromagnetic actuator mainly includes a housing 10, an electromagnetic field generator, a permanent magnet 40, an armature 50, a push rod 60, and two magnetic poles.

[0022] The housing 10 can be formed as a generally cylindrical component, having a circular, square, or other shaped cross-section. Other components of the electromagnetic actuator can be mounted into the cavity of the housing 10. The electromagnetic field generator is fixedly mounted inside the housing 10. Typically, the electromagnetic field generator can include an electromagnetic coil 20 and a coil support 30. The coil support 30 is a generally hollow cylindrical component, and the electromagnetic coil 20 is wound radially outward around the central axis of the coil support 30. The electromagnetic coil 20 is capable of generating an electromagnetic field when energized. The central axis of the coil support 30 defines the axial direction of the electromagnetic field generator and the entire electromagnetic actuator; that is, the axial direction of the electromagnetic actuator is parallel to the central axis of the coil support 30.

[0023] The permanent magnet 40 is also fixed to the coil support 30. Specifically, the permanent magnet 40 can be formed as a ring-shaped component roughly around the central axis of the electromagnetic field generator, coaxially fixed to the radially outer side of the coil support 30, and can be arranged in the axial central region of the electromagnetic field generator, particularly at approximately the axial center point. The permanent magnet 40 is made of permanent magnet material, thereby enabling it to generate a permanent magnetic field.

[0024] The electromagnetic actuator has two magnetic poles arranged axially spaced apart, located at opposite ends of the electromagnetic field generator. These two magnetic poles are stationary relative to the housing 10 and the electromagnetic field generator, and can be directly and fixedly mounted to the housing 10. To distinguish between the two magnetic poles, the pole extending towards the push rod 60 is called the front magnetic pole 70a, and the pole extending towards the retraction direction of the push rod 60 is called the rear magnetic pole 70b. The front magnetic pole 70a and the rear magnetic pole 70b are made of soft magnetic material, and therefore can be magnetized under the magnetic field of the permanent magnet 40. Typically, the front magnetic pole 70a and the rear magnetic pole 70b can be arranged approximately symmetrically about the permanent magnet 40.

[0025] The armature 50 is formed as a generally cylindrical component and is mounted radially inside the electromagnetic field generator in an axially movable manner. The armature 50 is capable of being acted upon by an electromagnetic force in the electromagnetic field, and thus can be driven by the electromagnetic force of the electromagnetic field generator to move axially within the inner cavity of the electromagnetic field generator (relative to the electromagnetic field generator and the housing 10). The axial movement range of the armature 50 is defined by the front magnetic pole 70a and the rear magnetic pole 70b between a first limit position and a second limit position: in the first limit position ( Figure 1a The armature 50 abuts against the front magnetic pole 70a and cannot move further axially away from the rear magnetic pole 70b; in the second limit position ( Figure 1b The armature 50 abuts against the rear magnetic pole 70b and cannot move further axially away from the front magnetic pole 70a.

[0026] The push rod 60 is formed as a generally elongated cylindrical component, which is fixed generally coaxially to the radially inner side of the armature 50, thereby enabling it to move synchronously with the armature 50. The push rod 60 passes axially through the armature 50 such that its two axial ends protrude axially beyond the armature 50. The end of the push rod 60 extending out of the armature 50 toward the front magnetic pole 70a further extends through the front magnetic pole 70a and beyond the housing 10 to engage a component to be driven by the electromagnetic actuator, such as a ratchet.

[0027] Even when the electromagnetic field generator is not powered on, the front magnetic pole 70a and rear magnetic pole 70b, magnetized by the magnetic field of the permanent magnet 40, can generate magnetic attraction forces to attract the armature 50. When the electromagnetic field generator is powered on, the electromagnetic force generated by the electromagnetic field on the armature 50 can drive the armature 50 to overcome the magnetic attraction forces generated by the magnetic poles under the magnetic field of the permanent magnet and move in any axial direction (the direction can be changed based on the current direction), and eventually reach the limit position of abutting the corresponding magnetic pole. At this time, the electromagnetic field generator can be de-powered, and at the same time, the magnetic attraction forces generated by the magnetic poles abutting the armature 50 under the magnetic field of the permanent magnet can attract the armature 50.

[0028] Figure 4aThe graph shown illustrates the relationship between the magnetic attraction force generated by the magnetic poles under the magnetic field of the permanent magnet and the moving position of the armature 50. The middle curve represents the resultant force exerted by the two magnetic poles on the armature 50, while the upper and lower curves represent the individual forces exerted by the two magnetic poles on the armature 50. Figure 4a As can be seen from the curve, the magnetic attraction generated by each magnetic pole increases rapidly within a certain distance of the armature 50 when it approaches that magnetic pole. Therefore, the armature 50, when pressed against the magnetic pole, can be firmly attracted by the magnetic pole, and thus can be stably held in any extreme position even without power. However, this sudden increase in magnetic attraction also means that as the armature 50 moves towards a certain magnetic pole, it will suddenly accelerate and collide with the magnetic pole when it approaches, thus generating a large impact force and noise.

[0029] To address this impact phenomenon, an elastic buffer is provided between the armature 50 and the magnetic pole in the electromagnetic actuator according to this invention. For example... Figure 1a and Figure 1b As shown, such an elastic buffer can be provided between the armature 50 and any magnetic pole. Preferably, the electromagnetic actuator may include two such elastic buffers disposed axially between the armature 50 and the front magnetic pole 70a, and axially between the armature 50 and the rear magnetic pole 70b. For ease of distinction, the elastic buffer disposed between the armature 50 and the front magnetic pole 70a may be referred to as the front elastic buffer 80a, and the elastic buffer disposed between the armature 50 and the rear magnetic pole 70b may be referred to as the rear elastic buffer 80b. The front elastic buffer 80a may be positioned on one of the armature 50 and the front magnetic pole 70a, and the rear elastic buffer 80b may be positioned on one of the armature 50 and the rear magnetic pole 70b. When the armature 50 is in the first extreme position ( Figure 1a The front elastic buffer 80a, arranged between the armature 50 and the front magnetic pole 70a, is compressed axially by both, thereby generating an elastic force that separates them axially. When the armature 50 is in the second extreme position ( Figure 1b When the armature 50 and the rear magnetic pole 70b are compressed axially, the rear elastic buffer 80b is compressed by both, thereby generating an elastic force that separates them axially. The elastic force generated by the two elastic buffers to separate the armature 50 from the magnetic pole is always less than the magnetic attraction force generated by the magnetic pole under the magnetic field of the permanent magnet. Therefore, this elastic force can buffer the impact between the armature 50 and the magnetic pole to reduce noise, but it will not prevent the armature 50 from contacting the magnetic pole, nor will it separate the armature 50 that has already contacted the magnetic pole from the magnetic pole.

[0030] Based on combination Figure 4aAnalysis shows that the magnetic attraction force causing the impact only increases significantly when the armature 50 is very close to the magnetic pole. Therefore, to avoid interfering with the movement of the armature 50, each elastic buffer is preferably only compressed by the armature 50 and the corresponding magnetic pole when the armature 50 is close to the corresponding magnetic pole. In most of the middle section of the movement range of the armature 50, each elastic buffer is preferably not compressed, so that no elastic force is applied to the armature 50. Specifically, the movement range of the armature 50 between the first extreme position and the second extreme position can be divided into a first end section, a second end section, and an intermediate section. The first end section is the end section adjacent to the first extreme position (including the first extreme position). In the first end section, the armature 50 and the front magnetic pole 70a jointly compress the front elastic buffer 80a, while the rear elastic buffer 80b is not compressed and therefore does not undergo elastic deformation. The second end section is the end section adjacent to the second extreme position (including the second extreme position). In the second end section, the armature 50 and the rear magnetic pole 70b jointly compress the rear elastic buffer 80b, while the front elastic buffer 80a is not compressed and therefore does not undergo elastic deformation. The intermediate section is the section connecting the first and second end sections. When the armature 50 is located in the intermediate section, the front elastic buffer 80a and the rear elastic buffer 80b are not compressed and therefore do not undergo elastic deformation. By controlling the shape and size of the elastic buffers, the stroke length of the two end sections can be changed, thereby allowing the compression distance of the elastic buffers to be controlled within a desired range as needed.

[0031] Various components with elastic deformation capabilities can be used as elastic buffers. Based on installation requirements, wave springs are preferably used as elastic buffers. For example, in... Figure 1a and 1b In the illustrated embodiment, the front elastic buffer 80a and the rear elastic buffer 80b are respectively formed as wave springs arranged around the axial direction. Various forms of wave springs can be applied to this electromagnetic actuator. Figure 2a The wave spring shown consists of only a single spring ring. Figure 2b The wave spring shown has multiple independent spring rings stacked along the axial direction. Figure 2c The wave spring shown is composed of multiple layers of spirally extended spring rings. Wave springs of the above type or other types can serve as the front elastic buffer 80a and / or the rear elastic buffer 80b.

[0032] Wave springs have a small axial dimension and can generate a large elastic force with a small axial deformation. Figure 4bThe graph illustrates the relationship between the elastic force of the wave spring and the axial compression. As shown, the elastic force of the wave spring changes similarly to the magnetic attraction of a magnetic pole; when the compression exceeds a certain level, the elastic force also increases rapidly. Therefore, wave springs are very suitable as elastic buffer components for electromagnetic actuators, providing a greater buffering effect over short approach distances.

[0033] Elastic buffers in the form of wave springs are also easy to install. For example... Figure 3a and Figure 3b As shown, the front elastic buffer 80a and the rear elastic buffer 80b, in the form of wave springs, can respectively surround the radially outer side of the push rod 60. More preferably, as... Figure 1a and Figure 1b As shown, to facilitate the distribution of the electromagnetic field, the front magnetic pole 70a typically includes a front protrusion 71a that convexes axially toward the armature 50, while the rear magnetic pole 70b includes a rear protrusion 71b that convexes axially toward the armature 50. Correspondingly, the armature 50 includes a front recess 51a that is axially recessed from the axial end face toward the front magnetic pole 70a and a rear recess 51b that is axially recessed from the axial end face toward the rear magnetic pole 70b. The push rod 60 passes through the front recess 51a and the rear recess 51b, respectively. In the first extreme position, the armature 50 is stopped by abutting the front magnetic pole 70a with its axial end face toward the front magnetic pole 70a, while the front protrusion 71a is inserted but not abutting the front recess 51a. In the second extreme position, the armature 50 is stopped by abutting the rear magnetic pole 70b with its axial end face toward the rear magnetic pole 70b, while the rear protrusion 71b is inserted but not abutting the rear recess 51b. The front elastic buffer 80a can be installed in the front recess 51a. In the first extreme position, the front elastic buffer 80a is compressed between the top of the front protrusion 71a and the bottom of the front recess 51a. The rear elastic buffer 80b can be installed in the rear recess 51b. In the second extreme position, the rear elastic buffer 80b is compressed between the top of the rear protrusion 71b and the bottom of the rear recess 51b. In this arrangement, the existing axial clearance between the pole protrusion and the armature recess can be used to accommodate the elastic buffer. Since the axial dimension of the wave spring is small, the wave spring-type elastic buffer is easy to arrange in such a recess.

[0034] In some embodiments, when the elastic buffer in the form of a wave spring is arranged radially outward of the push rod 60, such as Figure 3a As shown, the front elastic buffer 80a and / or the rear elastic buffer 80b can be constrained radially by the push rod 60. At this time, the radial clearance between the outer surface of the push rod 60 and the inner surface of the elastic buffer is small, which allows the elastic buffer to undergo axial compression deformation on the one hand, and restricts the elastic buffer from making significant radial movement relative to the push rod 60 on the other hand.

[0035] In other embodiments, when a wave spring-type elastic buffer is arranged in a recess in the armature 50, the recess can also constrain the elastic buffer radially. Specifically, as Figure 3b As shown, the front recess 51a can radially constrain the front elastic buffer 80a, and the rear recess 51b can radially constrain the rear elastic buffer 80b. At this time, the radial gap between the outer surface of the elastic buffer and the inner surface of the recess is small, which on the one hand allows the elastic buffer to undergo axial compression deformation, and on the other hand restricts the elastic buffer from making significant radial movement relative to the armature 50.

[0036] In the electromagnetic actuator according to this invention, an elastic buffer disposed between the armature and the magnetic pole provides a certain buffering force when the armature abuts the magnetic pole, thereby reducing impact noise. The elastic force generated by the elastic buffer can, to a certain extent, counteract the magnetic attraction of the magnetic pole to the armature, making it easier for the armature to separate from the magnetic pole when the armature moves again upon energization, thus shortening the locking and unlocking response time. However, by controlling the magnitude of the elastic force, it can be prevented from affecting the stable adsorption state between the magnetic pole and the armature. The elastic buffer can be a wave spring, which requires little installation space and can generate sufficient elastic force with a small amount of compression, thus facilitating its installation in the electromagnetic actuator. By controlling the parameters of the elastic buffer, it can adapt to the force requirements of various electromagnetic actuators.

[0037] While possible embodiments have been described exemplarily in the foregoing description, it should be understood that numerous variations of the embodiments exist through combinations of all known and readily conceived technical features and implementation methods. Furthermore, it should be understood that the exemplary embodiments are merely examples and do not in any way limit the scope, application, or construction of this invention. The foregoing description is more intended to provide those skilled in the art with technical guidance for transforming at least one exemplary embodiment, wherein various changes, particularly regarding the function and structure of the components, can be made without departing from the scope of the claims.

[0038] Appendix Label Table

[0039] 10. Shell

[0040] 20 Electromagnetic coils

[0041] 30 Coil Holder

[0042] 40 permanent magnets

[0043] 50 Armature

[0044] 51a Front recess

[0045] 51b Recessed portion

[0046] 60 putter

[0047] 70a Front magnetic pole

[0048] 71a Forward protrusion

[0049] 70b rear magnetic pole

[0050] 71b Rear protrusion

[0051] 80a Front Elastic Buffer

[0052] 80b rear elastic buffer

Claims

1. An electromagnetic actuator, comprising an electromagnetic field generator, a permanent magnet (40), an armature (50), a front magnetic pole (70a), and a rear magnetic pole (70b), wherein the electromagnetic field generator and the permanent magnet (40) are arranged coaxially, the front magnetic pole (70a) and the rear magnetic pole (70b) are respectively located at the two ends of the axial direction of the electromagnetic field generator, the armature (50) is mounted on the radially inner side of the electromagnetic field generator and is capable of being driven by the electromagnetic force of the electromagnetic field generator to move axially relative to the electromagnetic field generator between a first limit position and a second limit position, the armature (50) abuts against the front magnetic pole (70a) at the first limit position and against the rear magnetic pole (70b) at the second limit position, the front magnetic pole (70a) and the rear magnetic pole (70b) are respectively capable of being magnetized by the permanent magnet (40) to generate a magnetic attraction force to attract the armature (50), characterized in that, The electromagnetic actuator further includes a front elastic buffer (80a) and / or a rear elastic buffer (80b), the front elastic buffer (80a) being arranged axially between the armature (50) and the front magnetic pole (70a) such that when the armature (50) is in the first extreme position, the armature (50) and the front magnetic pole (70a) compress the front elastic buffer (80a) axially, and the rear elastic buffer (80b) being arranged axially between the armature (50) and the rear magnetic pole (70b) such that when the armature (50) is in the second extreme position, the armature (50) and the rear magnetic pole (70b) compress the rear elastic buffer (80b) axially.

2. The electromagnetic actuator according to claim 1, characterized in that, The front elastic buffer (80a) is positioned on one of the armature (50) and the front magnetic pole (70a), and / or the rear elastic buffer (80b) is positioned on one of the armature (50) and the rear magnetic pole (70b).

3. The electromagnetic actuator according to claim 1, characterized in that, The front elastic buffer (80a) and the rear elastic buffer (80b) are respectively formed as wave springs arranged around the axial direction.

4. The electromagnetic actuator according to claim 3, characterized in that, The electromagnetic actuator further includes a push rod (60) which is fixed to the radially inner side of the armature (50) and passes through the armature (50) axially. The front elastic buffer (80a) and the rear elastic buffer (80b) surround the radially outer side of the push rod (60), respectively.

5. The electromagnetic actuator according to claim 4, characterized in that, The push rod (60) radially constrains the front elastic buffer (80a) and / or the rear elastic buffer (80b).

6. The electromagnetic actuator according to claim 4, characterized in that, The front magnetic pole (70a) includes a front protrusion (71a) axially protruding toward the armature (50), and the rear magnetic pole (70b) includes a rear protrusion (71b) axially protruding toward the armature (50). The armature (50) includes a front recess (51a) axially recessed from the axial end face toward the front magnetic pole (70a) and a rear recess (51b) axially recessed from the axial end face toward the rear magnetic pole (70b). The push rod (60) passes through the front recess (51a) and the rear recess (51b) respectively. The front elastic buffer... (80a) is installed in the front recess (51a), and the rear elastic buffer (80b) is installed in the rear recess (51b). At the first extreme position, the front protrusion (71a) is inserted into the front recess (51a), and the front elastic buffer (80a) is compressed between the front protrusion (71a) and the front recess (51a). At the second extreme position, the rear protrusion (71b) is inserted into the rear recess (51b), and the rear elastic buffer (80b) is compressed between the rear protrusion (71b) and the rear recess (51b).

7. The electromagnetic actuator according to claim 6, characterized in that, In the first extreme position, the armature (50) abuts against the front magnetic pole (70a) by its axial end face toward the front magnetic pole (70a), and in the second extreme position, the armature (50) abuts against the rear magnetic pole (70b) by its axial end face toward the rear magnetic pole (70b).

8. The electromagnetic actuator according to claim 6, characterized in that, The front recess (51a) constrains the front elastic buffer (80a) in the radial direction, and / or the rear recess (51b) constrains the rear elastic buffer (80b) in the radial direction.

9. The electromagnetic actuator according to any one of claims 1 to 8, characterized in that, The range of movement of the armature (50) between the first extreme position and the second extreme position is divided into a first end section, a second end section and an intermediate section. The first end section is adjacent to the first extreme position, the second end section is adjacent to the second extreme position, and the intermediate section is connected between the first end section and the second end section. When the armature (50) is located in the intermediate section, the front elastic buffer (80a) and the rear elastic buffer (80b) are not compressed.

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