Electromagnetic clutch and method of actuating electromagnetic clutch

Abstract

An electromagnetic clutch includes a shift sleeve disposed on a shaft for common rotation therewith and linearly displaceable along the shaft between a first engaged position, a second engaged position, and a disengaged position between the engaged positions; first and second clutch bodies axially spaced from each other and each coaxially aligned with the shaft, each clutch body having internal teeth; and a stator having a first energizable coil and a second energizable coil. The shift sleeve has first teeth for engaging the internal teeth of the first clutch body in a first engaged position and second teeth for engaging the internal teeth of the second clutch body in a second engaged position. The clutch further comprises a locking device which prevents the shift sleeve from moving beyond the disengaged position in the direction of another engaged position when the shift sleeve is moved out of the engaged position in the direction of the disengaged position. A method of actuating a clutch is also provided.

Description

Technical Field

[0001] The invention relates to an electromagnetic clutch and a method for actuating an electromagnetic clutch. Background Art

[0002] In fact, the term "electromagnetic clutch" means that the clutch is electromagnetically actuated. However, when the clutch is closed, torque can be transmitted by form fit and / or friction. In other words, the clutch shifts gears through a combination of magnetic and mechanical forces.

[0003] If torque is to be temporarily transferred from one shaft to another shaft aligned coaxially therewith, without the two shafts being permanently connected, a clutch is typically used. A distinction is made here between friction clutches and dog clutches. The present invention is limited to dog clutches.

[0004] For chiseled clutches, sliding shift sleeves are usually used. These shift sleeves have one or more different teeth that engage with counter teeth to form a chiseled engagement via which torque can be transferred from one shaft to the other.

[0005] Electromagnetic clutches are known in the prior art, in which a shift sleeve is adjusted by means of a coil exerting a magnetic force on the shift sleeve. In such clutches, the shift sleeve can be moved in opposite directions from a disengaged position to engage the shift sleeve with different axially spaced clutch bodies.

[0006] In the case of prior art clutches, overshoot of the shift sleeve may occur during disengagement when the shift sleeve moves from the engaged position back to the disengaged position. This means that the shift sleeve moves beyond the disengaged position so that the shift sleeve may inadvertently engage with the opposite clutch body, thereby transmitting torque for a short time. Summary of the invention

[0007] SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide an improved electromagnetic clutch in which overshoot of a shift sleeve can be easily prevented.

[0008] According to the present invention, this object is achieved by an electromagnetic clutch, which includes: a shift sleeve, which is arranged on a shaft to rotate together with it and can be linearly displaced along the shaft between a first engagement position, a second engagement position and a disengagement position, the disengagement position being located between the engagement positions; a first clutch body and a second clutch body, which are axially spaced from each other and each is coaxially aligned with the shaft, each clutch body having internal teeth; and a stator, which has a first energizable coil and a second energizable coil for directly or indirectly adjusting the shift sleeve along the shaft. The shift sleeve has a first tooth for engaging the internal teeth of the first clutch body in the first engagement position, and a second tooth for engaging the internal teeth of the second clutch body in the second engagement position. In addition, the electromagnetic clutch includes a locking device, which prevents the shift sleeve from moving beyond the disengagement position in the direction of another engagement position when the shift sleeve moves out of the engagement position in the direction of the disengagement position.

[0009] The locking device prevents the shift sleeve from overshooting beyond the disengaged position when disengaging, thereby ensuring that the shift sleeve does not engage with the other clutch body.

[0010] In the engaged position, there is a particularly positive engagement between the shift sleeve and one of the two clutch bodies.

[0011] When the shift sleeve is in the disengaged position, no torque is transmitted. Therefore, the disengaged position represents the neutral position.

[0012] The locking device comprises, for example, a locking element which is a bolt which can be radially displaced between a release position and a locking position. Such a locking element is easy to implement and therefore cost-effective, while reliably preventing the movement of the shift sleeve.

[0013] In particular, the locking element mechanically prevents overshooting of the shift sleeve, so that fine position control is not necessary.

[0014] By blocking the shift sleeve with a mechanical stop, the shifting time can be shortened. In other words, the control for engagement and disengagement is simplified.

[0015] For example, the electromagnetic clutch comprises a plurality of circumferentially distributed locking elements. This allows the individual locking elements to be designed to be smaller than when there is only one locking element, thereby achieving an overall compact design of the electromagnetic clutch.

[0016] The locking element is acted on to the release position by means of an elastic element, for example. This ensures that the displacement of the shift sleeve will not be prevented unintentionally. In addition, the locking element can be moved back to the release position without energy consumption.

[0017] When the shift sleeve moves from the disengaged position to the engaged position, the locking element can overcome the spring force of the elastic element and move to the locked position. When the shift sleeve is in the engaged position, the locking element is therefore already in the locked position, so that during the subsequent disengagement process, the locking element reliably prevents any movement beyond the disengaged position.

[0018] Preferably, the locking element is mounted in the shift sleeve so as to be radially displaceable. Therefore, when the clutch is actuated, the locking element moves in one direction along the shaft together with the shift sleeve. This makes it possible to lock the shift sleeve in a position other than the disengagement position.

[0019] The recess is provided, for example, in the shift sleeve, through which recess the locking element extends.

[0020] In particular, the shift sleeve is split in the middle and the two parts of the shift sleeve are axially fastened to one another by a connecting ring in which the locking element is guided in a radially displaceable manner. The connecting ring thus has a dual function as a fixing element and as a guide element. In this way, a compact design of the clutch is achieved. Since the shift sleeve is split in the middle, it can be produced cost-effectively, since the individual components are small in volume.

[0021] The two parts of the shift sleeve are preferably identical.

[0022] According to one embodiment, the clutch comprises an armature coupled to the shift sleeve, the armature being displaceable along the first axis by energizing the first coil or the second coil of the stator. The displacement of the shift sleeve by the coil is therefore carried out indirectly by means of the armature. This allows the material of the shift sleeve to be selected independently of its magnetic properties. More specifically, for example, the torque transmission component can be hardened without having to take into account the magnetic properties of the shift sleeve. The torque transmission component can in particular be magnetically decoupled from the armature.

[0023] The armature can be designed in multiple parts and have, for example, a magnetic core and a plastic drive element which is firmly connected to the magnetic core. This also contributes to the cost-effective production of the clutch.

[0024] The armature is preferably detachably coupled to the shift sleeve in the direction of movement by means of a locking element. In this case, detachably coupled means that a relative movement between the armature and the shift sleeve in the direction along the axis is possible, in particular the armature can be displaced to a limited extent relative to the shift sleeve. The detachable coupling provides the shift sleeve with greater freedom of movement, allowing the shift sleeve to overlap the clutch body to a large extent.

[0025] The armature can be coupled to the shift sleeve via two elastic spring elements, which rest against opposite axial surfaces of the armature and each rest against the shift sleeve with one end facing away from the armature. The armature is clamped in the shift sleeve in particular by the spring elements. The spring elements generate a restoring force on the armature, so that after a displacement of the shift sleeve relative to the armature, during which one of the spring elements is compressed, the shift sleeve can be restored to a neutral position by the elastic force of the compressed spring element.

[0026] In conjunction with this embodiment, the two-part production of the shift sleeve also has a positive effect. In particular, the armature and the spring element can be inserted into the shift sleeve before the parts of the shift sleeve are connected to each other by means of a connecting ring.

[0027] The spring element is, for example, a spiral spring or a wave ring or a combination of these elements.

[0028] A drive geometry can be provided on the armature for a snap-fit ​​coupling of the armature with the locking element, the drive geometry having a step or a ramp which is configured such that when the shift sleeve is displaced relative to the armature, the locking element moves from the release position to the locking position by moving along the step or ramp, and vice versa. The movement of the locking element is thus mechanically influenced by the geometry of the armature, so that no additional drive is required for adjusting the locking element, which contributes to a compact and cost-effective design of the clutch.

[0029] When moving from the release position to the locking position, the locking element may move out of the drive geometry or remain in the drive geometry.

[0030] Due to the snap-fit ​​connection of the armature to the locking element, the armature is also connected by means of the locking element to the shift sleeve, in which the locking element is radially mounted.

[0031] The guide surface is provided, for example, on the outside of the first shaft, on which the locking tooth is arranged centrally, against which the locking element abuts when moving from the engaged position to the disengaged position. Mechanical stopping is achieved in a simple manner by means of such a locking tooth.

[0032] The locking element has, for example, a toothed tip at its end pointing toward the shaft.

[0033] According to one embodiment, the clutch comprises a retaining device which is arranged to hold the shift sleeve in the disengaged position or in the engaged position in the de-energized state of the coil. The clutch can thus be operated in a particularly energy-saving manner, since only magnetically effective shifting forces are required to actively shift the shift sleeve. In other words, the retaining device prevents unintentional shifting without actuation of the armature.

[0034] The holding device is in particular a mechanical holding device.

[0035] For example, the retaining device has at least one retaining element which is mounted in the shaft and acts elastically on the shift sleeve, and the shift sleeve has three axially spaced recesses in the region of the retaining element, the retaining element at least partially protruding into the corresponding recesses in the engaged position or disengaged position of the shift sleeve. The at least one retaining element thus secures the shift sleeve against unintentional displacement, while the movement of the shift sleeve cannot be hindered when a force greater than the retaining force of the retaining element is applied to the shift sleeve in the displacement direction.

[0036] The retaining element is, for example, a ball which rests against the shift sleeve and acts on the shift sleeve by means of a spring element.

[0037] When viewed in a longitudinal section through the shift sleeve, at least one of the recesses may have a triangular profile. This profile allows the retaining element to exert a restoring force on the shift sleeve once the retaining element is arranged in the recess. Alternatively, a semicircular profile of the recess is also possible.

[0038] According to one embodiment, the locking device may include a control unit that is configured to adjust the energization of the first coil and the second coil so that when the shift sleeve is displaced from the engaged position in the direction of the disengaged position, the shift sleeve is prevented from moving beyond the disengaged position in the direction of the other engaged position. In this way, the position of the shift sleeve can be adjusted entirely by means of the magnetic forces of the two coils. The mechanical locking surface can be omitted. A locking element can also be provided in this embodiment, but in this case, the locking element is only used to couple the armature to the shift sleeve and has no locking function.

[0039] This object is further achieved by a method for actuating an electromagnetic clutch according to the invention. In a first method step, when the shift sleeve is in the disengaged position, the first coil or the second coil is energized so that the shift sleeve moves in the direction of the corresponding engaged position. During the movement of the shift sleeve from the disengaged position to the engaged position, in particular at the latest when the engaged position is reached, the locking element moves out of the release position to the locking position in the radial direction. During the subsequent movement of the shift sleeve from the engaged position in the direction of the disengaged position by energizing the other coil, the locking element prevents the shift sleeve from moving to the disengaged position.

[0040] As already explained in conjunction with the clutch according to the invention, this prevents the shift sleeve from moving beyond the disengagement position during disengagement.

[0041] The movement of the shift sleeve is preferably caused on the one hand by the magnetic force generated by the coil and on the other hand by the torque. In particular, once the shift sleeve overlaps the clutch body, the torque acting on the shift sleeve generates a force in the shifting direction, thereby achieving a greater overlap with the clutch body. More specifically, the combination of magnetic force and mechanical shifting force makes it possible to achieve a greater shifting stroke, thereby increasing the torque capacity of the clutch.

[0042] The locking element can be moved to the release position by re-energizing the first or second coil that has been energized to move the shift sleeve to the engaged position, thereby allowing the shift sleeve to return to the disengaged position. The fact that a current pulse is required to release the lock ensures that the locking element cannot be inadvertently moved back to the release position, making the locking particularly reliable.

[0043] In an alternative embodiment, after energizing the other coil, energization is stopped, causing the armature to move back to its initial position and the locking element to be able to move back to the release position. This means that when disengaged, as long as the coil is energized to move the armature or the shift sleeve, the locking element remains in the locked position, initially preventing the shift sleeve from moving to the disengaged position. Once energization is stopped, the locking element can move back to the release position and the shift sleeve can move back to the disengaged position without the need for further current pulses.

[0044] If the electromagnetic clutch comprises a retaining device as described above, the shift sleeve can be reset into the disengaged position by the retaining device, in particular by the retaining element pressing against the inclined surface of the recess of the shift sleeve when acted upon, which recess is triangular in longitudinal section. This also contributes to energy-saving operation of the electromagnetic clutch.

[0045] For example, when the shift sleeve is moved into the disengaged position, the locking element is moved from the locked position into the released position.

[0046] Alternatively, the locking element may be moved from the locking position to the releasing position before the shift sleeve is moved into the disengaging position.

[0047] This object is further achieved by a method for actuating an electromagnetic clutch according to the present invention, the method comprising a control unit. When the shift sleeve is in the disengaged position, the first coil or the second coil is energized so that the shift sleeve moves in the direction of the corresponding engaged position. During the subsequent movement of the shift sleeve from the engaged position in the direction of the disengaged position, the control unit adjusts the energization of the first coil and the second coil so that when the shift sleeve is displaced from the engaged position in the direction of the disengaged position, the shift sleeve is prevented from moving beyond the disengaged position in the direction of the other engaged position. No mechanical locking element is required to perform this method. BRIEF DESCRIPTION OF THE DRAWINGS

[0048] Further advantages and features of the present invention will become apparent from the following description and the accompanying drawings, with reference to which:

[0049] Figure 1 The electromagnetic clutch according to the present invention is shown in an exploded view,

[0050] Figure 2 Shown through Figure 1 A perspective cutaway view of the shift sleeve and armature of the electromagnetic clutch,

[0051] Figure 3 Shown through Figure 2 Another perspective cutaway view of the shift sleeve and armature of the electromagnetic clutch,

[0052] Figure 4 Shown through Figure 1 A longitudinal section through the clutch in the region of the retaining device of the clutch in the neutral position of the clutch,

[0053] Figure 5 Shown through Figure 1 A longitudinal sectional view of a clutch in the region of a locking element in a neutral position of the clutch,

[0054] Figure 6 Shown through Figure 1 A longitudinal section through the region of the retaining device of the clutch in the engaged state,

[0055] Figure 7 Shown through Figure 1 A longitudinal section through the locking element region of the clutch during the engagement process,

[0056] Figure 8 Shown through Figure 1 A longitudinal section through the locking element region of the clutch in the engaged state,

[0057] Fig. 9 Shown through Figure 1 A longitudinal section through the region of the locking element of the clutch during the disengagement process,

[0058] Fig.10 Shown through Figure 1 Cross section of the clutch,

[0059] Fig.11 Schematically shows a cross-sectional view of the holding device area,

[0060] Fig.12 shows a perspective sectional view through a shift sleeve, a stator and an armature of an electromagnetic clutch according to another embodiment of the present invention,

[0061] Fig.13It shows that the Fig.12 A longitudinal section through the shift sleeve, stator and armature of a clutch in the region of a retaining device in the neutral position of the clutch,

[0062] Fig.14 Shown through Fig.13 A longitudinal sectional view of the connecting ring region of the clutch in the neutral position of the clutch,

[0063] Fig.15 Shown through Fig.13 A longitudinal sectional view of a clutch in the region of a locking element in a neutral position of the clutch,

[0064] Fig.16 Shown through Fig.13 A longitudinal section through the region of the retaining device of the clutch in the engaged state,

[0065] Fig.17 Shown through Fig.13 A longitudinal cross-sectional view of the connecting ring region of the clutch in the engaged state,

[0066] Fig.18 Shown through Fig.13 A longitudinal section through the locking element region of the clutch in the engaged state,

[0067] Fig.19 Shown through Fig.13 Cross section of the clutch,

[0068] Fig. 20 Shown in neutral position Fig.13 A schematic cross-sectional view of a clutch,

[0069] Fig.21 Shown in an engaged state Fig.13 A schematic cross-sectional view of a clutch,

[0070] Fig. 22 Shown in an engaged state Fig.13 A schematic cross-sectional view of a clutch,

[0071] Fig.23 Shows Fig.13 Schematic cross-sectional view of a clutch during a disengagement process,

[0072] Fig.24 Shows the disengaged state Fig.13 A schematic cross-sectional view of a clutch,

[0073] Fig.25 shows a perspective sectional view of an electromagnetic clutch according to another embodiment of the present invention,

[0074] Fig.26 shows the movement through the neutral position Fig.25 A longitudinal cross-sectional view of the clutch, and

[0075] Fig. 27 Shown is a diagram of a Fig.25 A longitudinal cross-sectional view of a clutch. DETAILED DESCRIPTION

[0076] Figure 1 An electromagnetic clutch 10 is shown.

[0077] The clutch 10 includes a shaft 12 , a first clutch body 14 , a second clutch body 16 , a shift sleeve 18 and a stator 20 .

[0078] The stator 20 accommodates a first energizable coil 22 and a second energizable coil 24, which can be Figure 4 Furthermore, the stator 20 comprises a steel body 23 which together with the coils 22, 24 forms an electromagnet.

[0079] A shifting force can be generated by energizing the coils 22 , 24 .

[0080] The clutch bodies 14, 16 are axially spaced apart and each is coaxially aligned with the shaft 12. Figures 4 to 9 The cross-sectional view in FIG.

[0081] Each clutch body 14 , 16 has internal teeth 26 .

[0082] The shift sleeve 18 is arranged on the shaft 12 for common rotation therewith and is linearly displaceable along the shaft 12 between a first engaged position, a second engaged position and a disengaged position between the engaged positions. The various positions will be explained in more detail below.

[0083] In the exemplary embodiment, the shift sleeve 18 is displaced indirectly by means of the armature 28 . Figures 2 to 10 The armature 28 can be displaced axially by energizing the coils 22, 24. In particular, a force is generated on the armature 28 by the magnetic field generated when one or both coils 22, 24 are energized.

[0084] However, it is also conceivable that the shift sleeve 18 can be displaced directly by energizing the coils 22 , 24 .

[0085] In the exemplary embodiment, the shaft 12 has external teeth 30 that engage with internal teeth 32 of the shift sleeve 18 .

[0086] At its opposite ends, the shift sleeve 18 has first and second teeth 34 and 35, respectively, which are each formed as external teeth for torque-transmitting engagement with the internal teeth 26 of the clutch bodies 14, 16 to transmit torque between the shift sleeve 18 and the clutch bodies 14, 16 when the shift sleeve 18 is in the engaged position.

[0087] The first teeth 34 and the second teeth 35 are in particular dog-type teeth.

[0088] The teeth 32, 34, 35 of the shift sleeve 18 are Figure 2 and Figure 3 As can be seen more clearly in FIG. 2 , both figures each show a perspective sectional view of the shift sleeve 18 with the armature 28 .

[0089] References below Figure 2 and Figure 3 The shift sleeve 18 and the armature 28 and their coupling are described in detail.

[0090] In the exemplary embodiment, the shift sleeve 18 is designed in two parts. In particular, the shift sleeve 18 is divided in the middle, and the two parts of the shift sleeve 18 are identical.

[0091] The two parts of the shift sleeve 18 are connected by a connecting ring 36 (see Figure 3 ) are axially fastened to each other. The connecting ring 36 is Fig.10 This can also be seen in , which shows a cross section through the clutch 10 .

[0092] In particular, the connecting ring 36 and parts of the shift sleeve 18 have latching lugs 37 , 38 , by means of which the connecting ring 36 and parts of the shift sleeve 18 are held in engagement.

[0093] An in particular annular shielding element 39 is arranged at each axial end of the shift sleeve 18, which shielding element ensures that the shift sleeve 18 does not stick magnetically to the clutch bodies 14, 16. The shielding element 39 can be made of stainless steel or a plastic material.

[0094] The armature 28 is also designed in multiple parts and has a ferromagnetic core 40, which is at least partially surrounded by a jacket 41. The jacket 41 is made of plastic, for example, and serves as a magnetic barrier for the other clutch components.

[0095] From the cross section, the armature 28 is designed in multiple parts, in particular, the majority is T-shaped. In other words, the armature 28 has a web 43 extending toward the shift sleeve 18 (see Figure 3 ).

[0096] From the overall point of view, the armature 28 is annular. Fig.10 It can be seen in.

[0097] The armature 28 is guided on teeth 34 , 35 of the shift sleeve 18 .

[0098] The armature 28 is coupled to the shift sleeve 18 via two elastic spring elements 42 .

[0099] The spring element 42 rests on opposite axial surfaces of the armature 28 , more precisely on opposite surfaces of the web 43 .

[0100] The spring elements 42 each rest on the shift sleeve 18 with one end facing away from the armature 28 .

[0101] Therefore, the armature 28 is coupled to the shift sleeve 18 in the axial direction, and a relative movement between the armature 28 and the shift sleeve 18 in the axial direction is possible by compression of the spring element 42. In other words, the armature 28 is detachably coupled to the shift sleeve 18.

[0102] In the exemplary embodiment, the spring element 42 is formed from a set of wave springs.

[0103] In order to enable the armature 28 to move relative to the shift sleeve 18, the shift sleeve 18 has a circumferential recess 44 (see Figure 3 ), the web 43 of the armature 28 extends into the recess 44.

[0104] Circumferential grooves 46 are provided on each of the axial end faces of the recess 44 and are used to position the spring element 42. More specifically, the spring elements 42 are each partially arranged in the grooves 46 so that the spring elements 42 are fixed to the grooves to prevent slipping out in the assembled state of the shift sleeve 18.

[0105] For example, Figure 2 As shown in the sectional view in FIG. 1 , the clutch 10 has a locking device 47 which comprises a plurality of locking elements 48 which are designed as screws in the exemplary embodiment.

[0106] For example, four circumferentially distributed locking elements 48 are provided (see also Fig.10 ).

[0107] The purpose of the locking element 48 is to prevent, in particular mechanically prevent, the shift sleeve 18 from moving beyond the disengaged position when the shift sleeve 18 is displaced in the direction of the disengaged position, as will be described in more detail below based on the description of the operating principle of the clutch 10 .

[0108] For this purpose, the locking element 48 can be in a released position (see Figure 2 and Figure 5 ) and locked position (see Figure 8 and Fig. 9 ) are radially displaced between.

[0109] A drive geometry 50 for the interlocking connection of the armature 28 with the locking element 48 is provided on the armature 28 (see Figure 2 and Figures 5 to 9 ).

[0110] In the exemplary embodiment, the drive geometry 50 is a recess 52 on the inner side of the armature 28, and one end of the locking element 48 is arranged in the recess 52 in the release position, such as Figure 2 shown.

[0111] In the exemplary embodiment, drive geometry 50 has a ramped surface 54 .

[0112] The locking element 48 is displaceably guided in the shift sleeve 18 , more precisely in the connecting ring 36 .

[0113] A corresponding recess 56 is provided in the shift sleeve 18 , through which the locking element 48 can extend, in particular when the locking element 48 is moved into the locking position.

[0114] exist Figure 4 In the cross-sectional view of , it can be seen that the clutch 10 further includes a retaining device 58.

[0115] The holding device 58 is designed to hold the shift sleeve 18 in the disengaged position or in the engaged position when the coils 22 , 24 are in the de-energized state.

[0116] For this purpose, the retaining device 58 comprises a plurality of retaining elements 60 which are inserted into the shaft 12 and act elastically on the shift sleeve 18 .

[0117] In the exemplary embodiment, the retaining elements 60 are spherical members, each of which is disposed in a radial recess 64 in the shaft 12 and partially protrudes from the shaft when the shift sleeve 18 is in the engaged position or in the disengaged position.

[0118] The retaining elements 60 are each acted upon in the direction of the shift sleeve 18 by means of a spring element 66 .

[0119] The shift sleeve 18 has three axially spaced-apart recesses 68 in the region of the retaining element 60 .

[0120] In the engaged position or the disengaged position of the shift sleeve 18 , the retaining element 60 projects at least partially into the corresponding recess 68 .

[0121] As the shift sleeve 18 moves from the disengaged position to the engaged position, the retaining element 60 is pushed further into the recess 64 in the shaft 12 against the spring force, thereby allowing axial movement of the shift sleeve 18 .

[0122] like Fig.10 It can be seen in FIG. 4 that the retaining element 60 is arranged offset in the circumferential direction relative to the locking element 48 .

[0123] One of the recesses 68 , in particular the central recess 68 , in which the retaining element 60 engages in the disengaged position of the shift sleeve 18 , has a triangular contour when viewed in a longitudinal section through the shift sleeve 18 .

[0124] The following will refer to Figures 4 to 9 The working principle of the clutch 10 , in particular the method of actuating the electromagnetic clutch 10 , is described.

[0125] Figure 4 and Figure 5 The clutch 10 is shown in each case in a neutral position, wherein the shift sleeve 18 is in a disengaged position.

[0126] The locking element 48 is in the release position, the locking element 48 being arranged in particular over the center of the locking tooth 70 .

[0127] The locking tooth 70 is arranged in the center of a guide surface 72 which is provided on the outside of the shaft 12 .

[0128] The height of the locking tooth 70 is selected so that the locking element 48 can move over the locking tooth 70 when the locking element is in its release position and moved axially, and abuts the locking tooth 70 when the locking element is in its locking position and moved axially.

[0129] The locking element 48 has, for example, a toothed tip 73 at its end pointing toward the shaft 12. In other words, the locking element 48 has a flat surface in the direction of the locking tooth 70.

[0130] The guide surface 72 is formed in particular by a longitudinal toothing of the shaft 12 being partially removed, for example by milling.

[0131] In the neutral position, the armature 28 is located over the center of the shift sleeve 18 and centered between the clutch bodies 14 , 16 .

[0132] If the clutch 10 is shifted, for example by energizing the first coil 22, a magnetic force is exerted on the armature 28, which causes the armature to be displaced to the right in the exemplary embodiment (see Figure 6 ).

[0133] The clutch body 14 serves as a stopper that limits the displacement path of the armature 28 .

[0134] The displacement of the armature 28 causes a corresponding displacement of the shift sleeve 18 , so that the teeth 34 of the shift sleeve 18 engage with the internal teeth 26 of the clutch body 14 .

[0135] The displacement is achieved on the one hand by a magnetic force acting on the armature 28 and on the other hand by a torque acting on the shift sleeve 18 .

[0136] Figure 7 In particular, the displacement of the shift sleeve 18 caused by the magnetic force is shown just before the teeth 34 of the shift sleeve 18 overlap the internal teeth 26 of the clutch body 14 . Figure 7 The state shown may first occur in which the shift sleeve 18 abuts the end face of the clutch body 14 with its teeth 34 until the internal teeth 26 of the clutch body 14 and the teeth 34 of the shift sleeve 18 are aligned to allow engagement and, due to the energy stored in the spring element 42, the shift sleeve 18 is moved into engagement with the internal teeth 26 of the clutch body 14.

[0137] Once the shift sleeve 18 overlaps the clutch body 14 due to the displacement of the armature 28, the shift sleeve 18 is further attracted toward the clutch body 14 due to the shape of the internal teeth 26 of the clutch body 14 and the teeth 34 of the shift sleeve 18 until the shift sleeve 18 abuts against the clutch body 14, as shown in FIG. Figure 6 and Figure 8 shown.

[0138] More specifically, this is achieved by the internal teeth 26 of the clutch bodies 14, 16 and the teeth 34 of the shift sleeve 18 having undercuts in the direction of the engagement position, which undercuts are designed so that the torque transmission between the shaft 12 or the shift sleeve 18 and the clutch bodies 14, 16 generates a force on the shift sleeve 18 in the direction of the engagement position.

[0139] The displacement path of the shift sleeve 18 in the direction of the engaging position is restricted by the abutment of the shift sleeve 18 against the clutch body 14 .

[0140] like Figure 6 It can be seen that one of the spring elements 42 , in particular the spring element 42 facing further away from the clutch body 14 , with which the shift sleeve 18 engages, is compressed.

[0141] The retaining element 60 is moved into a corresponding recess 68 of the shift sleeve 18 , so that an additional retaining force acts on the shift sleeve 18 .

[0142] When the shift sleeve 18 moves from the disengaged position to Figure 6 In the engaged position shown, the locking element 48 is moved to the locked position.

[0143] like Figure 5 As shown, when the shift sleeve 18 is in the disengaged position, the locking element 48 is initially in the released position.

[0144] An end of the locking element 48 facing away from the shaft 12 engages with a drive geometry 50 .

[0145] If the armature 28 is displaced by energizing the coil 22, and the shift sleeve 18 is thereby displaced by coupling with the armature 28 via the spring element 42, the locking element 48 is displaced together with the shift sleeve 18, initially to the extent that the locking element 48 is mounted in the shift sleeve 18. Figure 7 Status shown.

[0146] like Figure 7 As shown, the locking element 48 is initially retained in the released position.

[0147] If the shift sleeve 18 is moved further in the direction of the engaged position due to the torque-induced forces, the locking element 48 is pulled out of the drive geometry 50 by the movement of the shift sleeve 18 until a further movement of the armature 28 is blocked by a stop on the clutch body 14 .

[0148] During this movement, the locking element 48 moves out of the recess 52 and slides along the inclined surface 54, as a result of which the locking element 48 is pressed down to reach the locking position, as shown in FIG. Figure 8 shown.

[0149] The armature 28 may remain in the illustrated position during the engaged condition.

[0150] The shift sleeve 18 remains held in the engaged position (in particular by the torque and by the holding device 58 ).

[0151] To open the clutch 10, by energizing the second coil 24, the armature 28 is moved again in the disengaging direction, in particular until the armature 28 abuts against the opposing clutch body 16, as shown in FIG. Fig. 9 shown.

[0152] The shift sleeve 18 moves together with the armature 28 out of the engaged position.

[0153] However, since the locking element 48 is still in the locked position, the shift sleeve 18 is prevented from returning to the disengaged position.

[0154] More specifically, the locking element 48 abuts the locking tooth 70 .

[0155] In this way, the shift sleeve 18 is initially decelerated during the disengagement process, so that an undesired overshoot of the shift sleeve 18 beyond the disengagement position is reliably prevented.

[0156] To move the shift sleeve 18 back to the disengaged position, the energization of the coil 24 is stopped, so that both coils 22 , 24 are de-energized and the armature 28 can return to its initial position. The displacement of the armature 28 is achieved by the elastic energy stored in the spring element 42 .

[0157] When the armature 28 is displaced to its initial position, the recess 52 of the drive geometry 50 is located above the locking element 48 so that the locking element can be moved back to the release position.

[0158] In particular, the retaining device 58 returns the shift sleeve 18 to the disengaged position, more precisely because when the retaining element 60 is acted upon, it presses against an inclined surface of the recess 68 of the shift sleeve 18 which is triangular in longitudinal section. Fig.11 As shown in the schematic diagram.

[0159] Since the locking element 48 is no longer held in the locked position, when the shift sleeve 18 moves, the locking element 48 slides along the locking teeth 70 and is urged back to the released position.

[0160] The clutch 10 is then in its initial state again.

[0161] The shift sleeve 18 can be engaged in the same manner with the clutch body 16. For this purpose, the armature 28 is deflected in the opposite direction by energizing the respective other coil 22, 24.

[0162] The mechanical locking function makes it possible to move the armature 28 to its end position by appropriately energizing the coils 22, 24 for each shift operation, so that shorter shift times can be achieved. In particular, no complex position control is required.

[0163] Furthermore, the position of the armature 28 can be used to indirectly determine the position of the shift sleeve 18 .

[0164] refer to Figures 12 to 24 Another embodiment of the clutch 10 is described.

[0165] Figures 12 to 24 The clutch 10 shown differs from the clutch 10 described above primarily in the mounting of the locking element 48 .

[0166] The same reference numerals will be used hereinafter for the same structures having the same functions as known from the above-described embodiments, in which respect reference is made to the above explanations, and the differences between the various embodiments are discussed hereinafter in order to avoid repetitions.

[0167] Analogously to the preceding embodiment, the locking element 48 is designed as a radially displaceable bolt which is guided in the connecting ring 36 .

[0168] However, in contrast to the previous embodiment, the locking element 48 is acted into the release position by means of a resilient element 74, which in the exemplary embodiment is a spring, such as Fig.12 , Fig.15 and Fig.18 shown.

[0169] In this exemplary embodiment, the spring element 42 for coupling the armature 28 to the shift sleeve 18 is omitted, which is particularly Fig.14 and Fig.17 As can be seen in , these figures show a longitudinal section through the clutch 10 in the area between the locking element 48 and the holding device 58 .

[0170] Alternatively, the armature 28 is coupled to the shift sleeve 18 via a locking element 48 , as described below.

[0171] A drive geometry 50 with a recess 52 is also provided on the armature 28, the drive geometry 50 having a step 76 on both sides. As a result, the recess 52 is deeper in the central region than in the lateral regions.

[0172] In the central region, the contour of the recess 52 is preferably adapted to the contour of the locking element 48 .

[0173] In the neutral state of the clutch 10 , ie when the shift sleeve 18 is in the disengaged position, the elastic element 74 acts on the locking element 48 towards the drive geometry 50 or the deeper region of the center of the recess 52 , the armature 28 being thus detachably coupled to the shift sleeve 18 .

[0174] In particular, the locking element 48 is coupled in a force-fitting and form-fitting manner to the armature 28. As a result, when the armature 28 is moved, the locking element 48 is also displaced (in particular as long as the locking element 48 is in the release position).

[0175] In accordance with Figures 12 to 19 In the embodiment of FIG. 1 , there are a total of six locking elements 48 (see FIG. Figure 8 and Fig.19 ), which are distributed around the circumference, wherein the locking elements 48 do not necessarily have to be evenly spaced in the circumferential direction.

[0176] The retaining device 58 is substantially the same as the retaining device of the previous embodiment.

[0177] However, if Fig.13 and Fig.16 It can be seen that all recesses 68 in the shift sleeve 18 have a triangular cross section, whereas in the previous embodiment the two outer recesses 68 have a semicircular cross section.

[0178] according to Figures 12 to 19 The clutch 10 is actuated according to Figures 1 to 11 The actuation of the clutch 10 is only slightly different.

[0179] References below Figure 20 to Figure 24 Actuation of the clutch 10 is described.

[0180] Fig. 20The clutch 10 is shown in a neutral state.

[0181] The armature 28 and the shift sleeve 18 are in a neutral position or in a disengaged position.

[0182] When the first coil 22 is energized, the armature 28 is displaced, as shown in FIG. Fig. 20 As shown by the arrow pointing to the right in FIG. 4 , the shift sleeve 18 is displaced together with the armature 28 due to the coupling of the armature 28 to the locking element 48 .

[0183] exist Fig.21 In FIG. 1 , the shift sleeve 18 is shown in a position which can be achieved by purely magnetic forces.

[0184] The armature 28 has abutted the clutch body 14 , so further displacement of the armature 28 in the engagement direction is not possible.

[0185] However, there is already a certain overlap between the teeth 34 of the shift sleeve 18 and the internal teeth 26 of the clutch body 14 .

[0186] As already explained in conjunction with the previous embodiment, due to the special shape of the teeth with undercuts in the direction of the engagement position and the acting torque, the shift sleeve 18 is pulled further in the direction of the engagement position until the engagement position is reached. Fig. 22 Position shown.

[0187] During this movement of the shift sleeve 18, the locking element 48 is pulled out of the central region of the drive geometry 50 and is pressed downward over the step into the locked position, overcoming the spring force of the elastic element 74. In fact, this is because further movement of the armature 28 is blocked by the abutment against the clutch body 14, while the shift sleeve 18 can continue to move and thus be displaced relative to the armature 18.

[0188] As long as the coils 22, 24 are de-energized, the shift sleeve 18 and the armature 28 are held by the retaining device 58. Fig. 22 Position shown.

[0189] By energizing the other coil 24, disengagement is performed in the same manner as in the previous embodiment, the locking element 48 abutting the locking tooth 70 and initially preventing the shift sleeve 18 from returning to the disengaged position (see Fig.23 ).

[0190] The armature 28 cannot rest against the opposing clutch body 16 because the armature 28 is blocked by the drive geometry 50 on the locking element 48 .

[0191] To return the shift sleeve 18 to the disengaged position, the armature 28 is moved to the right again by briefly energizing the first coil 22 until the center region of the drive geometry 50 is located above the locking element 48 so that the locking element 48 can be moved into the release position due to the spring force.

[0192] like Fig.11 As shown, the retaining device 58, in particular the retaining elements 60, are pressed against the inclined surfaces of the triangular recesses 68 to perform the Fig.23 The position shown is reset to the disengaged position.

[0193] Figure 25 to Figure 27 Another embodiment of the electromagnetic clutch 10 is shown.

[0194] Figure 25 to Figure 27 The embodiment shown is based on Figures 12 to 24 The embodiment shown.

[0195] However, according to Figure 25 to Figure 27 In the embodiment shown, the locking element 48 does not have a locking function, but only a coupling function. In particular, as described above, the locking element 48 couples the armature 28 to the shift sleeve 18 .

[0196] The locking teeth 70 and the end 73 on the locking element 48 are omitted. Instead, the locking device 47 comprises a control unit 49 which regulates the energization of the first coil and the second coil so that when the shift sleeve is displaced from the engaged position in the direction of the disengaged position, the shift sleeve is prevented from moving beyond the disengaged position in the direction of the other engaged position.

Claims

1. An electromagnetic clutch (10), comprising: a shift sleeve (18) arranged on the shaft (12) to rotate together with the shaft and capable of linearly shifting along the shaft (12) between a first engaged position, a second engaged position and a disengaged position, the disengaged position being located between the engaged positions, a first clutch body (14) and a second clutch body (16) axially spaced from each other and each coaxially aligned with the shaft (12), each clutch body having internal teeth (26), and a stator (20) having a first energizable coil (22) and a second energizable coil (24) for directly or indirectly adjusting the shift sleeve (18) along the shaft (12), The shift sleeve (18) has a first tooth (34) and a second tooth (35), the first tooth being used to engage the internal tooth (26) of the first clutch body (14) in the first engagement position, and the second tooth being used to engage the internal tooth (26) of the second clutch body (16) in the second engagement position, and A locking device (47) is included. When the shift sleeve (18) moves out of the engagement position in the direction of the disengagement position, the locking device prevents the shift sleeve (18) from moving in the direction of another engagement position beyond the disengagement position.

2. The electromagnetic clutch (10) according to claim 1, characterized in that: The locking device (47) comprises a locking element (48) which is a bolt which is radially displaceable between a release position and a locking position.

3. The electromagnetic clutch (10) according to claim 2, characterized in that: The locking element (48) is acted upon by an elastic element (74) to the release position.

4. The electromagnetic clutch (10) according to claim 3, characterized in that: When the shift sleeve (18) moves from the disengaged position to the engaged position, the locking element (48) moves to the locked position against the spring force of the elastic element (74).

5. The electromagnetic clutch (10) according to any one of claims 2 to 4, characterized in that: The locking element (48) is installed in the shift sleeve (18) so as to be radially displaceable.

6. The electromagnetic clutch (10) according to claim 5, characterized in that: The shift sleeve (18) is divided in the center and the two parts of the shift sleeve (18) are axially fastened to one another by a connecting ring (36) in which the locking element (48) is guided in a radially displaceable manner.

7. The electromagnetic clutch (10) according to any one of the preceding claims, characterized in that The clutch (10) includes an armature (28) coupled to the shift sleeve (18), the armature (28) being displaceable along the first shaft (12) by energizing a first coil (22) or a second coil (24) of the stator (20).

8. The electromagnetic clutch (10) according to claim 7 and in addition to any one of claims 2 to 5, characterized in that The armature (28) is detachably coupled to the shift sleeve (18) in a displacement direction by means of the locking element (48).

9. The electromagnetic clutch (10) according to claim 7, characterized in that: The armature (28) is coupled to the shift sleeve (18) via two elastic spring elements (42) which rest against opposite axial surfaces of the armature (28) and each rest against the shift sleeve (18) with one end facing away from the armature (28).

10. The electromagnetic clutch (10) according to claim 8 or 9 and additionally according to claim 2, characterized in that A drive geometry (50) for the interlocking connection between the armature (28) and the locking element (48) is arranged on the armature (28), the drive geometry (50) having a step (76) or a ramp (54) which is configured such that when the shift sleeve (18) is displaced relative to the armature (28), the locking element (48) moves from the release position to the locking position by moving along the step (76) or the ramp (54), and vice versa.

11. An electromagnetic clutch (10) according to any of the preceding claims, if dependent on claim 2, characterized in that A guide surface (72) is provided on the outside of the first shaft (12), a locking tooth (70) being centrally arranged on the guide surface (72) against which the locking element (48) abuts when moving from the engaged position to the disengaged position.

12. The electromagnetic clutch (10) according to any one of the preceding claims, characterized in that The clutch (10) comprises a retaining device (58) which is arranged to retain the shift sleeve (18) in the disengaged position or in the engaged position when the coil (22, 24) is de-energized.

13. The electromagnetic clutch (10) according to claim 12, characterized in that: The retaining device (58) has at least one retaining element (60) which is mounted in the shaft and acts elastically on the shift sleeve (18), and the shift sleeve (18) has three axially spaced-apart recesses (68) in the region of the retaining element (60), the retaining element (60) at least partially protruding into the corresponding recesses (68) in an engaged position or a disengaged position of the shift sleeve (18).

14. The electromagnetic clutch (10) according to claim 13, characterized in that: At least one of the recesses (68) has a triangular contour when viewed in a longitudinal section through the shift sleeve (18).

15. The electromagnetic clutch (10) according to any one of the preceding claims, characterized in that The locking device (47) comprises a control unit, which is configured to adjust the energization of the first coil (22) and the second coil (24) so ​​that when the shift sleeve (18) is displaced from the engaged position in the direction of the disengaged position, the shift sleeve (18) is prevented from moving in the direction of the other engaged position beyond the disengaged position.

16. A method for actuating an electromagnetic clutch (10) according to any one of claims 1 to 14, the method comprising the following steps: When the shift sleeve (18) is in the disengaged position, the first coil (22) or the second coil (24) is energized, so that the shift sleeve (18) moves in the direction of the corresponding engaged position. During the movement of the shift sleeve (18) from the disengaged position to the engaged position, in particular at the latest when the engaged position is reached, the locking element (48) moves in the radial direction from the released position to the locked position, and During a subsequent movement of the shift sleeve (18) out of the engaged position in the direction of the disengaged position by energizing the further coil (22, 24), the locking element (48) prevents the shift sleeve (18) from moving into the disengaged position.

17. The method according to claim 16, characterized in that The locking element is moved to the release position by re-energizing the first coil (22) or the second coil (24) that was energized to move the shift sleeve (18) to the engaged position, thereby allowing the shift sleeve (18) to return to the disengaged position.

18. The method according to claim 16, characterized in that After the other coil (22, 24) is energized, the energization is stopped, so that the armature (28) moves back to its initial position and the locking element (48) can move back to the release position.

19. The method according to any one of claims 16 to 18, characterized in that In the electromagnetic clutch (10) according to any one of claims 11 to 15, the shift sleeve (18) is reset to the disengaged position by the retaining device (58), in particular by the retaining element (60) pressing against the inclined surface of a recess (68) of the shift sleeve (18) when acted upon, the recess being triangular in longitudinal section.

20. A method for actuating an electromagnetic clutch (10) according to claim 15, the method comprising the following steps: When the shift sleeve (18) is in the disengaged position, the first coil (22) or the second coil (22, 24) is energized, so that the shift sleeve (18) moves in the direction of the corresponding engaged position. During the subsequent movement of the shift sleeve (18) from the engaged position in the direction of the disengaged position, the control unit (49) adjusts the energization of the first coil (22) and the second coil (24) so ​​that when the shift sleeve (18) is displaced from the engaged position in the direction of the disengaged position, the shift sleeve (18) is prevented from moving beyond the disengaged position in the direction of the other engaged position.

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