Electromagnetically switchable form fit coupling and method for operating an electromagnetically switchable form fit coupling

Abstract

An electromagnetically switchable form-fit coupling (10) is shown, comprising: a driven axially movable component (16), an axially fixed component (24) for driving, and a stator (32) having at least one energized, repolarizable drive coil (36) for adjusting the axially movable component (16) along a shaft (12). The form-fit coupling (10) further includes a permanent magnet (38) for holding the movable component (16) in a terminated position and an elastic reset element (54) for transferring the movable component (16) from the terminated position to a starting position, wherein the holding force applied to the movable component (16) by the permanent magnet (38) in the terminated position is greater than the reset force of the reset element (54). Furthermore, a method for operating such an electromagnetically switchable form-fit coupling (10) is also shown.

Description

Technical Field

[0001] This invention relates to an electromagnetically switchable form-fit coupling. Furthermore, this invention relates to a method for operating the electromagnetically switchable form-fit coupling. Background Technology

[0002] Couplings are typically used to temporarily transfer torque from one shaft to another coaxially aligned with it without permanently connecting the two shafts. These are categorized into friction-fit couplings and form-fit couplings. This invention relates to form-fit couplings, which are referred to herein as form-fit couplings. For example, gear couplings and claw couplings belong to the category of form-fit couplings.

[0003] For form-fit couplings, a displaceable switching sleeve is typically used. The switching sleeve has teeth that engage with mating teeth to form a form fit, via which torque can be transmitted from a first shaft to a second shaft.

[0004] Electromagnetic couplings are known in the prior art, in which the adjustment of the switching sleeve is performed via a drive coil that applies magnetic force to the switching sleeve. In such couplings, the switching sleeve can be moved in one direction from a disengaged position to engage with the coupling body. Here, we discuss single-sided couplings.

[0005] Electromagnetically switchable form-fit couplings typically have at least one drive coil. By energizing the drive coil, a magnetic field is generated, which can displace the switching sleeve. To maintain the displaced state, particularly in the terminating position of the switching sleeve, the drive coil is typically kept energized with a small current during the holding state. Therefore, continuous energy is required to hold the switching sleeve in the terminating position. By disengaging the drive coil, the switching sleeve is displaced back to the starting position, where this switching process is typically supported by a resilient reset element.

[0006] In addition to needing to energize the drive coil in the terminated position, residual magnetism after the drive coil is turned off leaves a magnetic force, requiring the elastic reset element to overcome a relatively large force. This results in a delay in the switching process. Summary of the Invention

[0007] Therefore, an object of the present invention is to provide an electromagnetically switchable form-fit coupling, wherein continuous energization of the drive coil is not required, and wherein no delay due to residual magnetism occurs during switching. Furthermore, an object is to provide a method for operating the electromagnetically switchable form-fit coupling, the method requiring as little energy as possible.

[0008] According to the invention, the first objective is achieved by an electromagnetically switchable form-fit coupling comprising: a driven axially movable member arranged anti-rotationally on a shaft and capable of linear displacement along the axis between a starting position and an ending position. Furthermore, the form-fit coupling comprises: at least one driven axially fixed member coaxially aligned with the shaft; and a stator having at least one energized, repolarizable drive coil for adjusting the axially movable member along the shaft; wherein in the engaged position, a form fit exists between the axially movable member and the axially fixed member, thus providing a rotational connection between the shaft and the axially fixed member. The form-fit coupling further comprises: a permanent magnet for holding the movable member in the ending position; and a resilient reset element for transferring the movable member from the ending position to the starting position, wherein in the ending position, the holding force applied to the movable member by the permanent magnet is greater than the reset force of the reset element.

[0009] In other words, at least one permanent magnet is provided, and the magnetic force of the permanent magnet is strong enough to hold the axially movable part in the terminated position, so that the drive coil does not need to be energized during the holding process. Therefore, since the form-fit connection between the axially movable part and the fixed part is sufficiently secured by the permanent magnet, the electromagnetically switchable form-fit coupling requires less energy, thereby increasing the driving range, especially in electric vehicles. Furthermore, since the drive coil does not need to be energized during the holding process, no magnetic force remains in the drive coil when the movable part is displaced from the terminated position to the starting position.

[0010] The movable part can be a switching sleeve or an armature, while the fixed part can be the coupling body. The armature and / or the switching sleeve are preferably made of a ferromagnetic metal.

[0011] In one embodiment, the starting position is the disengaged position and the ending position is the engaged position; in an alternative embodiment, the starting position is the engaged position and the ending position is the disengaged position. Therefore, the electromagnetically switchable form-fit coupling can be normally open (NO) or normally closed (NC). Thus, it is not important whether the form-fit coupling is one in which the movable part is held in the engaged or disengaged position by a permanent magnet.

[0012] The stator of the form-fit coupling may additionally include a magnetic bridge between the drive coil and at least one permanent magnet. Here, the magnetic bridge serves to stabilize and enhance the magnetic field of the permanent magnet, preventing undesirable magnetic effects, especially during the displacement of the movable part. In other words, the magnetic bridge is used to prevent any deviation in the magnetic field of the permanent magnet, particularly during the switching on and off of the drive coil.

[0013] Although the magnetic bridge is preferably arranged between the coil and at least one permanent magnet, it can also be arranged on the side of the permanent magnet away from the drive coil.

[0014] According to one embodiment of the form-fit coupling, at least one drive coil, at least one permanent magnet, and / or a magnetic bridge are encapsulated or sealed within a non-conductive material. This non-conductive material can be, in particular, a non-magnetic material, such as plastic. This ensures that any magnetic component—the drive coil, permanent magnet, and / or magnetic bridge—is anchored at a predetermined location, and that the magnetic attraction or repulsion of these components does not cause displacement of the predetermined arrangement.

[0015] At least one permanent magnet may be, for example, a toroidal magnet, or may comprise at least two toroidal segments. From an economic perspective, toroidal segments are superior to toroidal magnets; that is, segments of the toroid that are discontinuous along the circumference of the toroid.

[0016] According to one embodiment, the stator and / or at least one permanent magnet is arranged in a stator housing. Therefore, the stator and permanent magnet are protected from external influences by the stator housing.

[0017] If a magnetic bridge is provided, the magnetic bridge can also be arranged in the stator housing.

[0018] Preferably, the stator housing is made of a soft magnetic material and has a radially inwardly projecting end section that is axially opposed to the movable part. This allows the stator housing to stabilize and enhance the magnetic field of at least one permanent magnet, enabling the movable part to be held in the terminated position without energizing the drive coil.

[0019] According to one embodiment, the stator housing comprises two L-shaped rings, one ring having a sleeve-shaped inner wall and a side wall projecting radially outward therefrom, and the other ring having a sleeve-shaped outer wall and a side wall projecting radially inward, the radially inner ends of the side walls forming end sections. Therefore, the stator housing, particularly the end sections, can provide a stop for a movable part, thereby defining the termination position of the movable part through the end sections of the stator housing.

[0020] Preferably, the radially inwardly projecting sidewall extends further inward than the sleeve-shaped inner wall. In other words, the end portion of the radially inwardly projecting sidewall is located outside the stator housing.

[0021] According to one embodiment, the stator, at least one permanent magnet, and a resilient reset element constitute a bistable system, wherein, when the coil is disconnected, the position of the axially movable component is stabilized in a starting position and an ending position by means of at least one permanent magnet and the resilient reset element, respectively. The permanent magnet and the resilient reset element create two stable states corresponding to the starting and ending positions, eliminating the need to energize the drive coil to hold the movable component in either the ending or starting position.

[0022] According to another embodiment, an electronic circuit is provided, which has an H-bridge for repolarizing the stator. Therefore, the movable part can be moved to a termination position or a starting position according to the polarization displacement of the drive coil. Thus, by using the electronic circuit with the H-bridge, the second drive coil can be discarded.

[0023] The elastic reset element is preferably a wave spring. Alternatively, a leaf spring or a coil spring can also be used.

[0024] According to the invention, this objective is also achieved by a method for operating an electromagnetically switchable form-fit coupling as described above. This method includes the following steps:

[0025] a) Electrify the stator to move the movable part from the starting position to the ending position;

[0026] b) Disconnect the drive coil after the movable part reaches the end position;

[0027] c) The movable part is held in the terminated position by means of at least one permanent magnet; and

[0028] d) Repolarize the stator and energize the repolarized stator to displace the movable part from the termination position to the starting position, at least with the support of a reset element.

[0029] Therefore, the basic idea of ​​this invention is that only the drive coil needs to be energized to displace the movable part, so as to save energy and avoid delays caused by residual magnetism.

[0030] As previously stated, the magnetic force of at least one permanent magnet is sufficient to hold the movable part in its terminated position, such that the drive coil does not need to be energized while the movable part is in its terminated position or its initial position.

[0031] According to a variation of the method, in step d), the movable part is displaced from the termination position to the starting position by means of an elastic reset element. Here, when the stator is repolarized and the axially movable part is displaced outward from its termination position, the spring force of the elastic reset element exceeds the magnetic force of at least one permanent magnet. In other words, by energizing the repolarized stator, the magnetic field of at least one permanent magnet can be reduced, thereby reducing the magnetic force acting on the movable part. By reducing the magnetic force of at least one permanent magnet, the spring force of the elastic reset element can exceed the magnetic force, thereby displacing the movable part outward from its termination position to the starting position. Depending on the magnitude of the spring force of the elastic reset element, the energy required to energize the drive coil can be reduced during the outward displacement from the termination position.

[0032] In step d), the stator repolarization can be performed, for example, by an electronic circuit with an H-bridge. Attached Figure Description

[0033] Other advantages and features of the invention will become apparent from the following description and the accompanying drawings. The drawings illustrate:

[0034] Figure 1 A schematic cross-sectional view of the electromagnetically switchable form-fit coupling according to the present invention in the disengaged position is shown.

[0035] Figure 2 Show Figure 1 The figure shown is a detailed cross-sectional view of the shape-fitting coupling in the stator region;

[0036] Figure 3 Show Figure 3 Magnetic field simulation of the cross-sectional diagram shown;

[0037] Figure 4 The cross-sectional diagram of the coupling at the engagement position shows a magnetic field simulation of the shape matching coupling. Detailed Implementation

[0038] Figure 1 An electromagnetically switchable form-fit coupling 10 is shown, which is used to couple a first shaft 12 and a second shaft 14 coaxially aligned with the first shaft 12 to each other by opening and closing.

[0039] Figure 1 The shape-fitting coupling 10 shown is an electromagnetic gear coupling, which has radially inward and radially outward extending, meshing teeth.

[0040] However, the electromagnetically switchable form-fit coupling 10 can also be any other type of gear coupling. The only important thing is that the connection is established through form fit.

[0041] The electromagnetically switchable form-fit coupling 10 includes a driven axially movable component 16, which in this embodiment is a switching sleeve 18 having a first tooth 20 radially inward along the circumference, the first tooth engaging with an external tooth on a first shaft 12.

[0042] Furthermore, the switching sleeve 18 is arranged anti-rotationally on the first shaft 12 and can be adjusted axially along the first shaft between an engaged position and a disengaged position. Figure 1 The switching sleeve 18 is shown in the disengaged position.

[0043] The second shaft 14 is axially fixed, and in the embodiment of the form-fit coupling 10, the coupling body 26 is anti-rotationally coupled to the second shaft 14. The shaft 14 can carry a component 24 fixedly connected to it, which together with the shaft 14 forms the coupling body 26.

[0044] The coupling body 26 has a second tooth 28, which is arranged along the outer circumference of the coupling body 26 (here, the outer circumference of component 24).

[0045] The first tooth 20 and the second tooth 28 together form the coupling tooth 30 and are used to: form a form fit between the switching sleeve 18 and the coupling body 26 in the engagement position of the switching sleeve 18.

[0046] Here, the coupling tooth 30 formed by the first and second tooth portions 20, 28 has an undercut at least at the teeth of the first tooth portion 20 and / or at the teeth of the second tooth portion 28. This undercut is configured such that when the switching sleeve 18 is in the engaged position and when torque is applied to the form-fit coupling 10, an additional displacement of the switching sleeve 18 toward the coupling body 26 occurs because the circumferential force is partially converted into an axial displacement force. For example, this can be achieved by a wedge-widened undercut, such that a wedge effect is formed in the direction of the engaged position when torque is transmitted.

[0047] In addition, a stator 32 is provided radially on the switching sleeve 18, the stator including a stator housing 34 and a drive coil 36, the drive coil being at least partially housed in the stator housing 34.

[0048] Furthermore, a permanent magnet 38 is arranged at one axial end in the stator housing 34, the permanent magnet being configured as a disc-shaped annular magnet. Alternatively, at least two annular sections may be provided to reduce the cost of the permanent magnet 38.

[0049] like Figure 2The stator housing 34, shown in more detail, consists of two L-shaped rings 40 and 42. Here, the first ring 40 has a sleeve-shaped inner wall 44 and a side wall 46 that protrudes radially outward from it, while the second ring 42 has a sleeve-shaped outer wall 48 and a side wall 50 that protrudes radially inward.

[0050] For example, especially in Figure 2 The radially inner end of the inwardly protruding sidewall 50 extends beyond the inner wall 44 and forms an end segment 52, which is axially opposite to the movable member 16.

[0051] Preferably, the stator housing 34, namely the first ring 40 and the second ring 42, is formed of a soft magnetic material.

[0052] The drive coil 36 arranged in the stator housing 34 is used to linearly adjust the switching sleeve 18 toward the coupling body 26 along the first shaft 12 toward the engagement position.

[0053] Alternatively, a drive coil 36 may be considered for adjusting the switching sleeve 18 toward the disengaged position along the first axis 12.

[0054] In principle, the drive coil 36 is used to adjust the switching sleeve 18 along the first axis 12 from the starting position to the ending position.

[0055] Depending on the type of the form-fit coupling 10, the starting position is either the disengaged position or the engaged position. Here, a form-fit coupling 10 whose starting position is the disengaged position and whose ending position is the engaged position is called a normally open type, while a form-fit coupling 10 whose starting position is the engaged position and whose ending position is the disengaged position is called a normally closed type.

[0056] The switching sleeve 18 is adjusted from the starting position to the ending position by the magnetic force applied to the switching sleeve 18 when the drive coil 36 is energized. Here, the magnetic field generated by the drive coil 36 is enhanced by the magnetic field of the permanent magnet 38.

[0057] In order to move the switching sleeve 18 back to the starting position, a flexible reset element 54 is provided, and the switching sleeve 18 is coupled to the first shaft 12 in an axially displaceable manner via the reset element.

[0058] In the shape-fitting coupling 10 shown in the attached figure, the elastic reset element 54 is a wave spring 56.

[0059] Here, a wave spring 56 is arranged between the switching sleeve 18 and the first shaft 12, such that the relative displacement of the switching sleeve 18 in the axial direction toward the termination position, which is the engagement position, causes compression of the wave spring 56. This creates a restoring force exerted by the wave spring 56 on the switching sleeve 18.

[0060] Here, the restoring force or spring force reacts against the magnetic force of the permanent magnet 38.

[0061] However, in order for the switching sleeve 18 to be held in the terminated position, i.e. the engaged position, the holding force applied to the switching sleeve 18 by the permanent magnet 38 is greater than the restoring force of the wave spring 56 in the terminated position.

[0062] The stator 32, permanent magnet 38, and wave spring 56 thus form a bistable system that can stabilize the position of the switching sleeve 18 in both the starting and ending positions. Here, when the drive coil 36 is disconnected, the permanent magnet 38 stabilizes the position of the switching sleeve 18 in the ending position, and the wave spring 56 stabilizes the position of the switching sleeve 18 in the starting position.

[0063] The wave spring 56 is arranged in the groove in the first shaft 12 and axially presses against the wall of the first shaft 12 on one hand and against the disc 58 fixed at the switching sleeve 18 on the other hand.

[0064] Therefore, the wave spring 56 is positioned in a space that is radially inwardly bounded by the first shaft 12 and radially outwardly bounded by the switching sleeve 18.

[0065] Especially in Figure 2 As can be seen in the detailed diagram, the shape-fit coupling 10 also includes a magnetic bridge 60, which is arranged within the stator housing 34 between the drive coil 36 and the permanent magnet 38. Alternatively, the magnetic bridge 60 may also be arranged on the side of the permanent magnet 38 opposite to the drive coil 36. The magnetic bridge 60 serves to enhance and stabilize the magnetic field of the permanent magnet 38.

[0066] The working principle and operation of the shape-fitting coupling 10 will be described below.

[0067] like Figure 2 , 3 As shown in Figure 4, in the embodiment of the form-fit coupling 10, the initial state is the disengaged position of the switching sleeve 18.

[0068] Here, there is no form fit between the first tooth 20 of the switching sleeve 18 and the second tooth 28 of the coupling body 26.

[0069] As long as no external force is applied to the switching sleeve 18 (the value of the external force exceeds the spring force of the wave spring 56), the switching sleeve 18 is held in the disengaged and disconnected state by the wave spring 56.

[0070] The shape of the coupling 10 is also referred to as "normally open".

[0071] As long as the switching sleeve 18 is in the initial position and is in the disengaged position, the spring force of the wave spring 56 is greater than the magnetic force of the permanent magnet 38.

[0072] If the switching sleeve 18 is to be displaced from the disengaged position toward the coupling body 26, sufficient voltage must first be applied to the drive coil 36 of the stator 32.

[0073] Here, the drive coil 36 is usually energized via a control device.

[0074] By energizing the drive coil 36, a magnetic field is generated by the drive coil 36. This magnetic field is superimposed on and amplified by the magnetic field of the permanent magnet 38. In other words, by energizing the drive coil 36, a magnetic field is generated in which the magnetic field lines extend parallel to the magnetic field lines generated by the permanent magnet 38, thereby increasing the magnetic flux density and thus increasing the magnetic field acting on the switching sleeve 18.

[0075] If the magnetic force of the drive coil 36 and the permanent magnet 38 exceeds the spring force of the wave spring 56 acting on the switching sleeve 18, the switching sleeve 18 will move toward the coupling body 26.

[0076] After the switching sleeve 18 reaches its terminated position, which is the engaged position, the drive coil 36 is disconnected. This is feasible because the magnetic force applied to the switching sleeve 18 by the permanent magnet 38, i.e., the holding force, in the terminated position of the switching sleeve 18 is greater than the spring force of the wave spring 56. Therefore, the magnetic force of the permanent magnet 38 is sufficient to reliably maintain the form fit formed by the first tooth 20 and the second tooth 28.

[0077] Therefore, the switching sleeve 18 is held in the terminated position only by the permanent magnet 38. The drive coil 36 is not energized.

[0078] In order to move the switching sleeve 18 back from the termination position to the starting position, i.e., to perform the disengagement process, the stator 32 is first repolarized.

[0079] The repolarization of the stator 32, particularly the repolarization of the drive coil 36, is performed here by an electronic circuit 62 including an H-bridge 64. For example, the circuit 62 may be housed in a control device 65.

[0080] If the repolarized drive coil 36 is now energized, the magnetic field of the drive coil 36 will again superimpose with the magnetic field of the permanent magnet 38. However, this time the magnetic force acting on the switching sleeve 18 is reduced because the magnetic field lines of the drive coil 36 and the permanent magnet 38 superimpose and cancel each other out.

[0081] Here, the magnetic force acting on the switching sleeve 18 decreases until the spring force of the wave spring 56 exceeds the magnetic force, so that the wave spring 56 can move the switching sleeve 18 from the end position back to the starting position.

[0082] exist Figure 3 and Figure 4 The magnetic fields of the permanent magnet 38 in the disengaged and engaged positions, i.e., the starting and ending positions, are shown respectively. It can be identified here that because the switching sleeve 18 is held in the ending position by the permanent magnet 38 and the wave spring 56 holds the switching sleeve 18 in the starting position, the magnetic field acting on the switching sleeve 18 in the ending position is significantly stronger than that in the starting position.

[0083] The following embodiment, not shown in the accompanying drawings, is in which at least one drive coil 36, permanent magnet 38, and magnetic bridge 60 are covered or encapsulated with a non-conductive material. By covering or encapsulating the magnetic components of the bistable system, it can be ensured that the magnetic attraction or repulsion caused by the polarization of the drive coil 36 does not cause undesirable displacement of the components.

[0084] The shape-fitting coupling 10 shown is characterized in that, in the final state of the switching sleeve 18, it is not necessary to energize the drive coil 36 to hold the switching sleeve 18 in its terminated position.

Claims

1. An electromagnetically switchable form-fit coupling (10), comprising: A driven axially movable component (16) is arranged anti-rotationally on a driven shaft (12) and is linearly displaceable between a starting position and an ending position along the shaft (12). At least one axial fixing component (24) is coaxially aligned with the shaft (12). In the engagement position, there is a form fit between the axially movable component (16) and the axially fixed component (24), thereby creating a rotational connection between the shaft (12) and the axially fixed component (24). The stator (32) has at least one energized, repolarizable drive coil (36) for adjusting the axially movable component (16) along the axis (12). At least one permanent magnet (38) for holding the movable part (16) in the terminated position, and A resilient reset element (54) is provided for transferring the movable part (16) from the termination position to the starting position, wherein the holding force applied to the movable part (16) by the permanent magnet (38) in the termination position is greater than the reset force of the reset element (54).

2. The electromagnetically switchable shape-fit coupling (10) according to claim 1, characterized in that, The starting position is the disengagement position and the ending position is the engagement position, or the starting position is the engagement position and the ending position is the disengagement position.

3. The electromagnetically switchable form-fit coupling (10) according to any one of the preceding claims, characterized in that, The stator (32) additionally includes a magnetic bridge (60) between the drive coil (36) and the at least one permanent magnet (38).

4. The electromagnetically switchable shape-fit coupling (10) according to claim 3, characterized in that, The at least one drive coil (36), the at least one permanent magnet (38), and / or the magnetic bridge (60) are encapsulated or sealed in a non-conductive material.

5. The electromagnetically switchable form-fit coupling (10) according to any one of the preceding claims, characterized in that, The at least one permanent magnet (38) is a ring magnet or includes at least two ring segments.

6. The electromagnetically switchable form-fit coupling (10) according to any one of the preceding claims, characterized in that, The stator (32) and / or the at least one permanent magnet (38) are arranged in the stator housing (34).

7. The electromagnetically switchable shape-fit coupling (10) according to claim 6, characterized in that, The stator housing (34) is made of soft magnetic material and has a radially inwardly projecting end section (52) which is axially opposite to the movable part (16).

8. The electromagnetically switchable shape-fit coupling (10) according to claim 7, characterized in that, The stator housing (34) consists of two L-shaped rings (40, 42), one of which (40) has a sleeve-shaped inner wall (44) and a side wall (46) that protrudes radially outward from it, and the other of which (42) has a sleeve-shaped outer wall (48) and a side wall (50) that protrudes radially inward, the radially inner end of the side wall forming the end segment (52).

9. The electromagnetically switchable form-fit coupling (10) according to any one of the preceding claims, characterized in that, The stator (32), the at least one permanent magnet (38), and the elastic reset element (54) form a bistable system in which the position of the axially movable component (16) is stabilized in the starting position and the ending position by means of the at least one permanent magnet and the elastic reset element (54) when the drive coil (36) is disconnected.

10. The electromagnetically switchable form-fit coupling (10) according to any one of the preceding claims, characterized in that, An electronic circuit (62) is provided, which has an H-bridge (64) for repolarizing the stator (32).

11. The electromagnetically switchable form-fit coupling (10) according to any one of the preceding claims, characterized in that, The elastic reset element (54) is a wave spring (56).

12. A method for operating an electromagnetically switchable form-fit coupling (10) according to any one of the preceding claims, wherein the method comprises the following steps: a) Electrify the stator (32) to move the movable part (16) from the starting position to the ending position; b) After the movable part (16) reaches the termination position, disconnect the drive coil (36). c) The movable part (16) is held in the termination position by means of at least one permanent magnet (38); and d) Repolarize the stator (32) and energize the repolarized stator (32) to displace the movable part (16) from the termination position to the starting position, at least with the support of the reset element (54).

13. The method according to claim 12, characterized in that, In step d), the movable part (16) is displaced from the termination position to the starting position by means of the elastic reset element (54), wherein when the stator (32) is repolarized and the axially movable part (16) is displaced outward from its termination position, the spring force of the elastic reset element (54) exceeds the magnetic force of the at least one permanent magnet (38).

14. The method according to claim 12 or 13, characterized in that, In step d), the repolarization of the stator (32) is performed by an electronic circuit (62) with an H-bridge (64).

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