Electromagnetic actuator
By introducing permanent magnets and elastic elements into the electromagnetic actuator, the problems of control accuracy and energy consumption caused by armature jamming are solved, achieving automatic recovery and energy-saving effects.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- SCHAEFFLER TECHNOLOGIES AG & CO KG
- Filing Date
- 2025-03-28
- Publication Date
- 2026-05-12
AI Technical Summary
In existing electromagnetic actuators used for parking lock applications, the armature may get stuck at the end of its stroke, resulting in high control precision requirements, poor energy efficiency, and the need for frequent power-on adjustments.
The design employs a permanent magnet and an elastic element. The permanent magnet keeps the armature in its extreme position when not energized, while the elastic element provides an automatic extension force for the push rod, ensuring that the armature automatically moves to its extreme position when stuck, thus avoiding the need for re-energization.
It enables the armature to automatically return to its limit position when stuck, reducing the control precision requirements and energy consumption, simplifying the control strategy, and reducing the number of frequent power-on steps.
Smart Images
Figure CN224233471U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of actuator technology. Specifically, this utility model relates to an electromagnetic actuator. 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 parking lock applications, electromagnetic actuators are typically used to actuate a pawl to engage a ratchet. Sometimes, the pawl may become stuck on the teeth of the ratchet. In this case, because the armature is not at the end of its travel, the magnetic attraction generated by the permanent magnet through its poles is weak when the power is off, insufficient to move the armature. Therefore, when the motor adjusts the ratchet position, the electromagnetic actuator must be re-energized to move the armature to the locked ratchet position. This adjustment method requires high control precision and is not energy-efficient. Utility Model Content
[0004] Therefore, the technical problem that this utility model needs to solve is to provide an improved electromagnetic actuator.
[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, a rear magnetic pole, and a push rod. The electromagnetic field generator and the permanent magnet are arranged coaxially. The front and rear magnetic poles are located at opposite ends 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 push rod is fixed to the armature and includes a first end that extends axially away from the armature and passes through the front magnetic pole. The electromagnetic actuator also includes an elastic element and a support. The support is fixedly mounted on the push rod and is located axially on the side of the front magnetic pole away from the rear magnetic pole. The elastic element elastically abuts against the support and the front magnetic pole or between the support and a component fixed relative to the front magnetic pole, thereby applying an elastic force that moves the support away from the front magnetic pole. The elastic element provides a thrust that extends the push rod outward from the front pole, so the push rod still has a tendency to extend even when no current is applied to push it out. When the armature and push rod get stuck in the middle of their travel due to external causes, the armature can automatically reach and stabilize at the first limit position once the external causes are removed, without needing to re-energize the armature.
[0006] According to a preferred embodiment of this invention, when the electromagnetic field generator does not apply electromagnetic force to the armature, the elastic force applied by the elastic element to the armature at the second limit position can be less than the magnetic attraction force generated by the rear magnetic pole on the armature, so that the elastic element cannot separate the armature at the second limit position from the rear magnetic pole. Therefore, this electromagnetic actuator still has bistable characteristics, and will only automatically drive the armature to move towards the first limit position when the armature is stuck in the middle of its stroke.
[0007] According to another preferred embodiment of the present invention, the elastic element can always be in a compressed state when the armature is located at any position between the first and second extreme positions. This means that the elastic element can always apply an elastic force to the push rod, causing the armature to tend to move towards the front magnetic pole.
[0008] According to another preferred embodiment of the present invention, the elastic element can be formed as a helical spring surrounding the radially outer side of the push rod. This elastic element is easy to install.
[0009] According to another preferred embodiment of the present invention, the push rod can constrain the elastic element radially. The push rod can be clearance-fitted with the elastic element, which on the one hand allows the elastic element to compress and deform axially, and on the other hand restricts significant radial movement of the elastic element.
[0010] According to another preferred embodiment of the present invention, the support may include a first recess facing the front magnetic pole, and the axial end of the elastic member facing the support is mounted in the first recess. The first recess can constrain the elastic member radially. Alternatively, the front magnetic pole may include a second recess facing the support, and the axial end of the elastic member facing the front magnetic pole is mounted in the second recess. The second recess can constrain the elastic member radially. These recesses can have a clearance fit with the elastic member, allowing the elastic member to compress and deform axially while limiting significant radial movement of the elastic member.
[0011] According to another preferred embodiment of the present invention, the push rod can pass through the support axially. Therefore, the push rod can still engage and drive external components through its end.
[0012] According to another preferred embodiment of the present invention, the first end can be inserted into the support and does not protrude from the support, and the end of the support with the front magnetic pole reversed is formed to be adapted to push against the driven component. This means that the engagement structure of the electromagnetic actuator and the driven component can be integrated into the support.
[0013] According to another preferred embodiment of the present invention, the support can be integrally formed with the push rod. This reduces the number of parts.
[0014] According to another preferred embodiment of the present invention, the push rod can be used to engage the ratchet by driving the pawl through the first end. When the pawl is engaged with the tooth of the ratchet, simply rotating the ratchet will automatically push the push rod out, thereby locking the ratchet with the pawl. This eliminates the need to re-energize the electromagnetic actuator. Attached Figure Description
[0015] 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:
[0016] Figure 1 A longitudinal sectional view of an electromagnetic actuator according to an exemplary embodiment of the present invention is shown;
[0017] Figure 2a and Figure 2b Show respectively Figure 1 A schematic diagram of the working state of the electromagnetic actuator;
[0018] Figure 3a and Figure 3b A perspective view and a cross-sectional view of an electromagnetic actuator according to another exemplary embodiment of the present invention are shown respectively;
[0019] Figure 4 A longitudinal sectional view of an electromagnetic actuator according to yet another exemplary embodiment of the present invention is shown; and
[0020] Figure 5A longitudinal sectional view of an electromagnetic actuator according to yet another exemplary embodiment of the present invention is shown. Detailed Implementation
[0021] 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.
[0022] 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.
[0023] Figure 1 A longitudinal sectional view of an electromagnetic actuator according to an exemplary embodiment of the present invention is shown. Figure 1 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.
[0024] 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.
[0025] 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.
[0026] 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.
[0027] 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 subject to 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 limited between a first limit position and a second limit position by the front magnetic pole 70a and the rear magnetic pole 70b: in the first limit position, 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, the armature 50 abuts against the rear magnetic pole 70b and cannot move further axially away from the front magnetic pole 70a.
[0028] 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 away from the armature 50 towards the front magnetic pole 70a can be referred to as the first end, while the end extending out of the armature 50 towards the rear magnetic pole 70b can be referred to as the second end. The first end of the push rod 60 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… Figure 2a and Figure 2b The pawl A shown.
[0029] 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.
[0030] like Figure 1 As shown, the electromagnetic actuator also includes an elastic element 90 and a support 80. The support 80 is fixedly mounted on the push rod 60 and is located axially on the side of the front magnetic pole 70a away from the rear magnetic pole 70b. That is, the support 80 is fixedly mounted on the portion of the push rod 60 extending beyond the front magnetic pole 70a. The elastic element 90 abuts generally axially between the support 80 and the front magnetic pole 70a, or generally axially between the support 80 and a component (e.g., a portion of the housing 10) fixed relative to the front magnetic pole 70a, thereby enabling the application of an elastic force that moves the support 80 away from the front magnetic pole 70a. For example, in Figure 1 In the preferred embodiment shown, the two axial ends of the elastic member 90 directly abut against the support 80 and the front magnetic pole 70a, respectively.
[0031] As the armature 50 moves toward the second extreme position, the elastic element 90 is subjected to axial compression. Within the range where the support 80 and the front magnetic pole 70a can simultaneously abut the elastic element 90, the elastic deformation of the elastic element 90 increases as the armature 50 approaches the second extreme position, and the elastic force generated therefrom also increases. Throughout the entire axial movement range of the armature 50, the elastic element 90 is in an elastically deformed state, particularly a compressed state, at least in a portion starting from the second extreme position, thereby applying an elastic force to the push rod 60 that tends to move the armature 50 toward the front magnetic pole 70a. Preferably, when the armature 50 is at any position between the first and second extreme positions (including the first and second extreme positions), the elastic element 90 can always be in a compressed state, thereby always applying an elastic force to the push rod 60 that tends to move the armature 50 toward the front magnetic pole 70a.
[0032] As mentioned earlier, this magnetic field generator still exhibits bistable characteristics. Therefore, when the electromagnetic field generator is not energized and thus does not apply an electromagnetic force to the armature 50, the elastic force generated by the elastic element 90 is insufficient to allow the armature 50 to overcome the magnetic attraction of the rear magnetic pole 70b and disengage from the second limit position. In other words, when the electromagnetic field generator does not apply an electromagnetic force to the armature 50 and the armature 50 is in the second limit position, the elastic force applied by the elastic element 90 to the armature 50 is less than the magnetic attraction of the rear magnetic pole 70b to the armature 50, preventing the elastic element 90 from separating the armature 50 from the rear magnetic pole 70b in the second limit position. However, by controlling the magnitude of the current, the electromagnetic field generator can generate a sufficiently large electromagnetic force, such that when energized, the electromagnetic force generated by the electromagnetic field generator can cause the armature 50 to overcome the elastic force applied by the elastic element 90 and move towards the rear magnetic pole 70b, and can also cause the armature 50 to overcome the magnetic attraction of the rear magnetic pole 70b and separate from it.
[0033] The elastic element 90 can be made of various suitable elastic components. Preferably, the elastic element 90 can be formed as a helical spring. The helical spring-shaped elastic element 90 can be wrapped around the radially outer side of the push rod 60, thereby facilitating the installation and positioning of the elastic element 90. The push rod 60 can constrain the elastic element 90 radially. Specifically, the push rod 60 can be clearance-fitted with the helical spring-shaped elastic element 90, the size of which allows the elastic element 90 to compress and deform axially on the one hand, and restricts the elastic element 90 from significant radial movement relative to the push rod 60 on the other hand.
[0034] Alternatively or additionally, the elastic element 90 in the form of a helical spring can also be constrained by a recess formed on the front magnetic pole 70a and / or the support 80. Specifically, in Figure 1 The embodiments and in Figure 3a and Figure 3b In another embodiment shown, the support 80 may include a first recess 81 facing the front magnetic pole 70a, through which the push rod 60 extends axially. An axial end of an elastic member 90 surrounding the push rod 60, facing the support 80, may be fitted into the first recess 81, which radially constrains the elastic member 90. Similarly, the front magnetic pole 70a may include a second recess 71a facing the support 80, into which the axial end of the elastic member 90 surrounding the push rod 60, facing the front magnetic pole 70a, may be fitted, which radially constrains the elastic member 90. Each recess may be clearance-fitted with an elastic member 90 in the form of a helical spring, the size of which allows the elastic member 90 to compress axially while limiting significant radial movement of the elastic member 90 relative to the recess.
[0035] The two methods of constraining the elastic element 90 through the recess and through the push rod can be used individually or simultaneously. For example, in Figure 4 In another embodiment shown, the front magnetic pole 70a and the support 80 do not have similar features. Figure 1 , Figure 3a and Figure 3b The recessed part, the elastic element 90 is constrained in the radial direction only by the push 60.
[0036] exist Figure 1 In the illustrated embodiment, the push rod 60 passes axially through the support 80 such that a first end of the push rod 60 protrudes from the side of the support 80 away from the front magnetic pole 70a. This allows the push rod to directly push against the driven component (e.g., pawl A) through its first end, or to mount additional components suitable for pushing against the driven component. Alternatively, the structure for pushing against the driven component (e.g., pawl A) can also be integrated into the support 80. For example, in Figure 3a and Figure 3b The illustrated embodiments and Figure 4In the embodiment shown, the first end of the push rod 60 is inserted into the support 80 and does not protrude from the support 80, and the end of the support 80 with the front magnetic pole 70a facing away from the magnetic pole is configured to push against the driven component (e.g., pawl A).
[0037] In various embodiments of the present invention, the support 80 can be fixedly assembled to the push rod 60 as a separate component or it can be integrally formed with the push rod 60. For example, in Figures 1-4 In the various embodiments shown, the support 80 is fixedly assembled to the push rod 60 as a separate component. Alternatively, in some other embodiments, the support 80 may also be integrally formed with the push rod 60. For example, as Figure 5 As shown, the support 80 can be formed as the flange of the push rod 60.
[0038] This type of electromagnetic actuator is particularly suitable for driving ratchet mechanisms, such as those in parking lock systems. Figure 2a and Figure 2b As shown, the push rod 60 can be directly or indirectly (e.g., via the first end) Figure 3a and Figure 3b The support 80 (or other additional components shown) drives the pawl A, thereby engaging the ratchet B. When the armature 50 moves to the first extreme position, the push rod 60 extends out of the housing 10 and presses down the pawl A, causing the pawl A to engage in the tooth groove of the ratchet B, thereby locking the ratchet B. Figure 2b When armature 50 moves to the second limit position, push rod 60 retracts into housing 10, pawl A (e.g., under the action of elastic reset element) lifts up and separates from ratchet B, thereby unlocking ratchet B. Figure 2a As shown, in some cases, during the process of the electromagnetic actuator being energized to press down pawl A, pawl A may become stuck on the tooth tip of ratchet B and fail to lock due to misalignment of ratchet B's rotation position. In this case, simply rotating ratchet B will allow push rod 90 to automatically extend under the action of elastic element 90 to press down pawl A and lock ratchet B, without needing to re-energize. Without elastic element 90, after rotating ratchet B, the electromagnetic actuator needs to be energized again for push rod 90 to press down pawl A and lock ratchet B.
[0039] The electromagnetic actuator according to this invention can reduce the risk of the armature unexpectedly stopping in the middle of its stroke. For example, when used to drive a ratchet mechanism, this electromagnetic actuator can automatically relock the ratchet without requiring re-energization. Therefore, this electromagnetic actuator can optimize control strategies and reduce energy consumption. Furthermore, this electromagnetic actuator has a simple structure and does not require many additional components. The support in the electromagnetic actuator can also be combined with the structure that engages the driven component, thereby reducing the number of parts.
[0040] 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.
[0041] Appendix Label Table
[0042] 10. Shell
[0043] 20 Electromagnetic coils
[0044] 30 Coil Holder
[0045] 40 permanent magnets
[0046] 50 Armature
[0047] 60 putter
[0048] 70a Front magnetic pole
[0049] 71a Second recess
[0050] 70b rear magnetic pole
[0051] 80 supports
[0052] 81 First recess
[0053] 90 Elastic element
[0054] A thorn
[0055] B. Ratchet
Claims
1. An electromagnetic actuator, comprising an electromagnetic field generator, a permanent magnet (40), an armature (50), a front magnetic pole (70a), a rear magnetic pole (70b), and a push rod (60), 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 can be driven by the electromagnetic force of the electromagnetic field generator to be relative to each other between a first limit position and a second limit position. As the electromagnetic field generator moves axially, the armature (50) abuts against the front magnetic pole (70a) at the first extreme position and against the rear magnetic pole (70b) at the second extreme position. The front magnetic pole (70a) and the rear magnetic pole (70b) are respectively magnetized by the permanent magnet (40) to generate a magnetic attraction force that attracts the armature (50). The push rod (60) is fixed to the armature (50) and includes a first end that extends axially away from the armature (50) and passes through the front magnetic pole (70a). The electromagnetic actuator further includes an elastic element (90) and a support (80), the support (80) being fixedly disposed on the push rod (60) and located axially on the side of the front magnetic pole (70a) away from the rear magnetic pole (70b), the elastic element (90) elastically abutting against the support (80) and the front magnetic pole (70a) or between the support (80) and a component fixed relative to the front magnetic pole (70a), thereby enabling the application of an elastic force that moves the support (80) away from the front magnetic pole (70a).
2. The electromagnetic actuator according to claim 1, characterized in that, When the electromagnetic field generator does not apply electromagnetic force to the armature (50), the elastic force applied by the elastic member (90) to the armature (50) at the second limit position is less than the magnetic attraction force generated by the rear magnetic pole (70b) on the armature (50), so that the elastic member (90) cannot separate the armature (50) at the second limit position from the rear magnetic pole (70b).
3. The electromagnetic actuator according to claim 2, characterized in that, When the armature (50) is located at any position between the first limit position and the second limit position, the elastic element (90) is in a compressed state.
4. The electromagnetic actuator according to claim 2, characterized in that, The elastic element (90) is formed as a helical spring surrounding the radially outer side of the push rod (60).
5. The electromagnetic actuator according to claim 4, characterized in that, The push rod (60) constrains the elastic element (90) in the radial direction.
6. The electromagnetic actuator according to claim 4, characterized in that, The support (80) includes a first recess (81) facing the front magnetic pole (70a), the axial end of the elastic member (90) facing the support (80) is mounted in the first recess (81), the first recess (81) constrains the elastic member (90) radially, and / or, the front magnetic pole (70a) includes a second recess (71a) facing the support (80), the axial end of the elastic member (90) facing the front magnetic pole (70a) is mounted in the second recess (71a), the second recess (71a) constrains the elastic member (90) radially.
7. The electromagnetic actuator according to claim 2, characterized in that, The push rod (60) passes through the support (80) axially.
8. The electromagnetic actuator according to claim 2, characterized in that, The first end is inserted into the support (80) and does not protrude from the support (80), and the end of the support (80) facing away from the front magnetic pole (70a) is formed to be adapted to push against the driven component.
9. The electromagnetic actuator according to claim 2, characterized in that, The support (80) is integrally formed with the push rod (60).
10. The electromagnetic actuator according to any one of claims 1 to 9, characterized in that, The push rod (60) is used to engage the ratchet (B) by driving the pawl (A) through the first end.