Electromagnetic clutch and operation method for electromagnetic clutch

Abstract

To identify an improved electromagnetic clutch that easily prevents an overshoot of a shift sleeve.SOLUTION: A shift sleeve (18) has first teeth that are engaged with internal teeth (26) of a first clutch body (14) in a first engagement position, and second teeth that are engaged with internal teeth (26) of a second clutch body (16) in a second engagement position. In addition, a clutch (10) comprises lock means for preventing the shift sleeve (18) from moving in a direction of another engagement position beyond a disengagement position when the shift sleeve (18) moves in a direction of the disengagement position from the engagement position.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to an electromagnetic clutch and a method of operating an electromagnetic clutch. [Background technology]

[0002] The term "electromagnetic clutch" refers to the fact that the clutch is electromagnetically actuated. However, when the clutch is closed, torque may be transferred in a form-fit and / or frictional manner. In other words, the clutch is shifted by a combination of magnetic and mechanical forces.

[0003] Clutches are usually used when the torque is temporarily transmitted from one shaft to another coaxially aligned shaft, without the two shafts being permanently connected. A distinction is made here between friction clutches and positive clutches. The present invention is limited to positive clutches.

[0004] For positive clutches, sliding shift sleeves are often used. These have one or more distinct teeth that mesh with counter teeth to create a positive mesh that can transfer torque from one shaft to another.

[0005] Electromagnetic clutches are known in the art in which a shift sleeve is modulated by a coil which exerts a magnetic force on the shift sleeve, and in such clutches the shift sleeve can be moved in opposite directions from a disengaged position to engage different axially spaced clutch bodies. DISCLOSURE OF THEINVENTION [Problem to be solved by the invention]

[0006] In prior art clutches, as the shift sleeve is returned from an engaged position to a disengaged position, it is possible for the shift sleeve to overshoot during disengagement, meaning that as the shift sleeve moves beyond the disengaged position, it may unintentionally engage the opposing clutch body and transfer torque for a short period of time.

[0007] Accordingly, one object of the present invention is to identify an improved electromagnetic clutch in which overshoot of the shift sleeve is easily prevented. [Means for solving the problem]

[0008] According to the present invention, this object is achieved by an electromagnetic clutch comprising a shift sleeve arranged on a shaft for integral rotation and linearly movable along the shaft between a first engaged position, a second engaged position, and a disengaged position located between the engaged positions, a first clutch body and a second clutch body spaced apart from each other in the axial direction and aligned coaxially with the shaft, each clutch body having internal teeth, and a stator having first and second energizable coils for directly or indirectly adjusting the shift sleeve along the shaft. The shift sleeve has first teeth for engaging with the internal teeth of the first clutch body at the first engaged position and second teeth for engaging with the internal teeth of the second clutch body at the second engaged position. The electromagnetic clutch further comprises a locking means for preventing the shift sleeve from moving beyond the disengaged position in the direction of another engaged position when the shift sleeve moves from the engaged position in the direction of the disengaged position.

[0009] The locking means prevents the shift sleeve from overshooting beyond the released position upon release and prevents the shift sleeve from engaging with other clutch bodies.

[0010] In the engaged position there is in particular a 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, thus representing a neutral position.

[0012] The locking means comprises a locking element, for example a bolt, which is radially movable between an open position and a locked position. Such a locking element is easy to implement and therefore cost-effective, while at the same time reliably blocking the movement of the shift sleeve.

[0013] In particular, the locking element mechanically prevents overshooting of the shift sleeve, and therefore does not require complex position control.

[0014] By blocking the shift sleeve with a mechanical stop, the shift time can be reduced, i.e. the control of engagement and disengagement is simplified.

[0015] For example, an electromagnetic clutch may include multiple locking elements distributed circumferentially, which allows each individual locking element to be designed smaller than if there was only one locking element, resulting in an overall compact design of the electromagnetic clutch.

[0016] The locking element is acted upon towards the release position, for example by an elastic element, so that the movement of the shift sleeve cannot be blocked unintentionally, and the locking element can be returned to the release position without consuming energy.

[0017] When the shift sleeve moves from the disengaged position to the engaged position, the locking element can move to the locked position against the spring force of the resilient element, so that when the shift sleeve is in the engaged position, the locking element is already in the locked position, so that during the subsequent disengagement process, the locking element reliably blocks movement of the shift sleeve beyond the disengaged position.

[0018] Preferably, the locking element is mounted radially movably within the shift sleeve such that when the clutch is actuated, the locking element moves in one direction along the shaft with the shift sleeve, thereby locking the shift sleeve in a position other than the released position.

[0019] In the shift sleeve, for example, there is a recess through which the locking element passes.

[0020] In particular, the shift sleeve is split in the middle, the two parts of the shift sleeve are axially fixed to one another by a connecting ring, and the locking element is guided radially movably in the connecting ring. The connecting ring thus has the dual function of a fixing element and 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 due to the small volume of the individual parts.

[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 movable along the shaft by energizing the first or second coil of the stator. The movement of the shift sleeve by the coil is thus performed indirectly by the armature. This allows the material of the shift sleeve to be selected independently of its magnetic properties. More specifically, the torque transmitting part can be, for example, hardened without having to take into account the magnetic properties of the shift sleeve. The torque transmitting part can in particular be magnetically decoupled from the armature.

[0023] The armature can be designed in several parts, for example having a magnetic core and a plastic drive element rigidly connected to the core, which also contributes to the cost-efficient manufacture of the clutch.

[0024] The armature is preferably removably connected to the shift sleeve in the direction of movement by the locking element, where removably connected means that a relative movement between the armature and the shift sleeve in the direction along the shaft is possible, in particular that the armature is movable to a limited extent relative to the shift sleeve, whereby the removably connected connection allows a greater freedom of movement of the shift sleeve and allows the shift sleeve to have a particularly large overlap with the clutch body.

[0025] The armature is connected to the shift sleeve via two elastic spring elements which contact opposite axial faces of the armature and contact the shift sleeve at their ends opposite the armature. The armature is fixed in the shift sleeve by the spring elements in particular. The spring elements generate a restoring force on the armature, so that after the shift sleeve has moved relative to the armature and one of the spring elements is compressed, the elastic force of the compressed spring element can restore the shift sleeve to a central position.

[0026] In connection with this embodiment, the two-part production of the shift sleeve also has positive effects: 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 one another by the connecting ring.

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

[0028] To ensure coupling between the armature and the locking element, there may be a drive feature on the armature, the drive feature having a step or bevel configured such that movement along the step or bevel moves the locking element from the open position to the locked position or vice versa when the shift sleeve moves relative to the armature. Thus, since the movement of the locking element is mechanically achieved by the armature feature, no additional drive is required to adjust the locking element, contributing to a compact and cost-effective design of the clutch.

[0029] When moving from the open position to the locked position, the locking element can either disengage from the driven configuration or remain within the driven configuration.

[0030] Due to the armature being positively connected to the locking element, the armature is also connected via the locking element to the shift sleeve, on which the locking element is radially attached.

[0031] For example, the shaft may have a guide surface on the outside thereof, a locking tooth arranged in the center thereof against which the locking element abuts when moving from the locked position to the released position, and such a locking tooth provides a simple mechanical stop.

[0032] The locking element may, for example, have a tooth-like tip at the end facing the shaft.

[0033] According to one embodiment, the clutch comprises a holding means adapted to hold the shift sleeve in the disengaged or engaged position with the coil de-energized. The clutch can therefore be operated in a particularly energy-efficient manner, since the magnetically effective shifting force is only required to actively move the shift sleeve. In other words, the holding means prevents unintended movement without actuating the armature.

[0034] The retention means are in particular mechanical retention means.

[0035] For example, the retaining means may comprise at least one retaining element mounted in the shaft and acting elastically on the shift sleeve, the shift sleeve having three axially spaced recesses in the region of the retaining element, the retaining elements at least partially projecting into the corresponding recesses in the engaged or disengaged position of the shift sleeve. In this way, the at least one retaining element fixes the shift sleeve against unintentional movement, but unhindered movement of the shift sleeve is possible when a force greater than the retaining force of the retaining element is applied to the shift sleeve in the direction of movement.

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

[0037] At least one of the recesses may have a triangular contour when viewed in a longitudinal section of the shift sleeve, which enables the retaining element to exert a restoring force on the shift sleeve as soon as it is placed in the recess. Alternatively, the recess may have a semicircular contour.

[0038] According to one embodiment, the locking means may include a control unit configured to adjust the energization of the first coil and the second coil such that, when the shift sleeve moves from an engaged position in the direction of a disengaged position, the shift sleeve is prevented from moving beyond the disengaged position in the direction of another engaged position. In this way, the position of the shift sleeve can be adjusted only by the magnetic force of the two coils. No mechanical locking surface is required. A locking element may also be present in this embodiment, but in this case the locking element serves only to couple the armature to the shift sleeve and does not have a locking function.

[0039] The object of the invention is further achieved by a method for operating an electromagnetic clutch according to the invention. In a first method step, while the shift sleeve is in a disengaged position, the first or second coil is energized, causing the shift sleeve to move 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 radially from the released position to the locked position. Thereafter, by energizing another coil, the locking element prevents the shift sleeve from moving in the disengaged position while the shift sleeve moves from the engaged position in the direction of the disengaged position.

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

[0041] The movement of the shift sleeve is preferably effected on the one hand by the magnetic force generated by the coil and on the other hand by the torque. In particular, as soon as the shift sleeve overlaps the clutch body, a force in the direction of movement is generated by the torque acting on the shift sleeve, so that a larger overlap with the clutch body is achieved. More specifically, the combination of the magnetic shift force and the mechanical shift force allows a larger shift movement to be realized, which increases the torque capacity of the clutch.

[0042] The locking element can be moved to the released position, and the shift sleeve can be returned to the disengaged position, by re-energizing the first or second coil that was energized to move the shift sleeve to the engaged position. Because a current pulse is required to release the lock, the locking element cannot inadvertently return to the released position, making the lock particularly reliable.

[0043] In another embodiment, after energizing another coil, it can be de-energized, the armature can return to its initial position, and the locking element can return to its open position. This means that upon disengagement, as long as the coil is energized to move the armature or shift sleeve, the locking element will remain in the locked position and initially prevent the shift sleeve from moving to the disengaged position. As soon as the energization is stopped, the locking element returns to the released position and the shift sleeve can return to the released position without the need for an additional current pulse.

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

[0045] Movement of the locking element from the locked position to the released position occurs, for example, when the shift sleeve moves to the disengaged position.

[0046] Alternatively, the locking element may be moved from the locked position to the released position before the shift sleeve is moved to the disengaged position.

[0047] The object of the present invention is further achieved by a method of operating an electromagnetic clutch according to the present invention, comprising a control unit. While the shift sleeve is in a disengaged position, the first or second coil is energized to move the shift sleeve towards a corresponding engaged position. Subsequently, while the shift sleeve moves from the engaged position towards the disengaged position, the control unit controls the energization of the first coil and the second coil such that when the shift sleeve moves from the engaged position towards the disengaged position, the shift sleeve is prevented from moving beyond the disengaged position towards another engaged position. No mechanical locking elements are required to perform such a method. [Brief description of the drawings]

[0048] [Figure 1] FIG. 1 shows an exploded view of an electromagnetic clutch of the present invention. [Diagram 2] FIG. 2 is a cross-sectional perspective view of a shift sleeve and an armature of the electromagnetic clutch of FIG. [Diagram 3] FIG. 3 shows another cross-sectional perspective view of the shift sleeve and the armature of the electromagnetic clutch of FIG. [Figure 4] FIG. 4 shows a longitudinal section through the clutch of FIG. 1 in the region of the holding means in the neutral position of the clutch. [Diagram 5] FIG. 5 shows a longitudinal section through the clutch of FIG. 1 in the region of the locking element in the neutral position of the clutch. [Figure 6] FIG. 6 shows a longitudinal section through the clutch of FIG. 1 in the region of the holding means in the engaged state. [Figure 7] FIG. 7 shows a longitudinal section through the clutch of FIG. 1 in the region of the locking element in the process of engagement. [Figure 8] FIG. 8 shows a longitudinal section through the clutch of FIG. 1 in the region of the locking element in the engaged state. [Figure 9] FIG. 9 shows a longitudinal cross-sectional view of the clutch of FIG. 1 during the disengagement process. [Figure 10] FIG. 10 shows a cross-sectional view of the clutch of FIG. [Figure 11] FIG. 11 shows a schematic cross section in the region of the holding means. [Figure 12] FIG. 12 shows a cross-sectional perspective view of a shift sleeve, a stator, and an armature of an electromagnetic clutch according to a further embodiment of the present invention; [Figure 13] FIG. 13 shows a longitudinal section through the region of the holding means of the clutch of the invention with the shift sleeve, stator and armature of FIG. 12 in the neutral position. [Figure 14] FIG. 14 shows a longitudinal section through the region of the connecting ring of the clutch of FIG. 13 in the neutral position. [Figure 15] FIG. 15 shows a longitudinal section through the clutch of FIG. 13 in the neutral position in the region of the locking element. [Figure 16]FIG. 16 shows a longitudinal section through the region of the holding means of the clutch of FIG. 13 in the engaged state. [Figure 17] FIG. 17 shows a longitudinal section of the clutch of FIG. 13 in the engaged state in the region of the connecting ring. [Figure 18] FIG. 18 shows a longitudinal section through the clutch of FIG. 13 in the region of the locking elements in the engaged state. [Figure 19] FIG. 19 shows a cross-sectional view of the clutch of FIG. [Figure 20] FIG. 20 shows a schematic cross-sectional view of the clutch of FIG. 13 in a neutral position. [Figure 21] FIG. 21 shows a schematic cross-sectional view of the clutch of FIG. 13 in an engaged state. [Figure 22] FIG. 22 shows a schematic cross-sectional view of the clutch of FIG. 13 in an engaged state. [Figure 23] FIG. 23 shows a schematic cross-sectional view of the clutch of FIG. 13 during the disengagement process. [Figure 24] FIG. 24 shows a schematic cross-sectional view of the clutch of FIG. 13 in a disengaged state. [Diagram 25] FIG. 25 is a schematic cross-sectional perspective view of an electromagnetic clutch according to a further embodiment of the present invention. [Figure 26] FIG. 26 shows a longitudinal cross-sectional view of the clutch of FIG. 25 in the neutral position. [Figure 27] FIG. 27 shows a longitudinal cross-sectional view of the clutch of FIG. 25 in an engaged condition. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0049] Further advantages and features of the present invention will become apparent from the following description and the accompanying drawings, to which reference is made and which are set forth above.

[0050] Fig. 1 shows an electromagnetic clutch 10. The clutch 10 is comprised of a shaft 12, a first clutch body 14, a second clutch body 16, a shift sleeve 18, and a stator 20. The stator 20 houses a first coil 22 and a second coil 24 that can be energized, as shown in Fig. 4. The stator 20 further includes a steel body 23, which, together with the coils 22, 24, forms an electromagnet.

[0051] A shift force can be generated by energizing the coils 22, 24.

[0052] The clutch bodies 14, 16 are axially spaced apart and each are coaxially aligned with the shaft 12. This is shown in cross-sectional view in Figures 4 to 9.

[0053] Each clutch body 14,16 has internal teeth 26.

[0054] A shift sleeve 18 is disposed on shaft 12 for rotation with shaft 12 and is linearly movable along shaft 12 between a first engaged position, a second engaged position, and a disengaged position located between the engaged positions, the various positions being described in more detail below.

[0055] In the illustrated embodiment, movement of the shift sleeve 18 is indirectly effected by an armature 28, seen in Figures 2-10. The armature 28 may be moved axially by energizing the coils 22, 24. In particular, a force is exerted on the armature 28 by a magnetic field generated by energizing one or both of the coils 22, 24.

[0056] However, it is also contemplated that the shift sleeve 18 may be moved directly by energizing the coils 22, 24.

[0057] In the illustrated embodiment, the shaft 12 has external teeth 30 that mesh with internal teeth 32 on the shift sleeve 18 .

[0058] The shift sleeve 18 has first and second teeth 34, 35 formed as external teeth at its opposite end. The first and second teeth 34, 35 are in torque transmitting engagement with the internal teeth 26 of the clutch bodies 14, 16 and serve to transmit torque between the shift sleeve 18 and the clutch bodies 14, 16 when the shift sleeve 18 is in the engaged position.

[0059] The first tooth 34 and the second tooth 35 are in particular dog teeth.

[0060] The teeth 32, 34, 35 of the shift sleeve 18 can be seen more clearly in Figures 2 and 3. Figures 2 and 3 show a cutaway perspective view of the shift sleeve 18 and armature 28.

[0061] The shift sleeve 18 and armature 28 and their connection are described in more detail below with reference to FIGS.

[0062] In this embodiment, the shift sleeve 18 is designed in two parts, in particular, the shift sleeve 18 is split in the middle, and the two parts of the shift sleeve 18 are identical.

[0063] The two parts of the shift sleeve 18 are axially fixed to one another by a connecting ring 36 (see FIG. 3), which is also shown in FIG.

[0064] In particular, portions of the connecting ring 36 and the shift sleeve 18 include latch lugs 37, 38 which hold the connecting ring 36 in engagement with portions of the shift sleeve 18.

[0065] At each axial end of the shift sleeve 18, a shielding element 39, in particular in the form of a ring, is arranged, which prevents the shift sleeve 18 from becoming magnetically attached to the clutch bodies 14, 16. The shielding elements 39 can be made of stainless steel or of a plastic material.

[0066] The armature 28 is also multi-section and has a ferromagnetic core 40 that is at least partially surrounded by a sheath 41. The sheath 41 may be made, for example, of plastic, and acts as a magnetic barrier to the other clutch components.

[0067] Viewed in cross section, the armature 28 is configured in part, in particular largely in the shape of a T. In other words, the armature 28 has a web 43 which extends towards the shift sleeve 18 (see FIG. 3).

[0068] Viewed as a whole, the armature 28 is ring-shaped, as shown in FIG.

[0069] The armature 28 is guided on the teeth 34 , 35 of the shift sleeve 18 .

[0070] The armature 28 is coupled to the shift sleeve 18 via two resilient spring elements 42 .

[0071] The spring element 42 abuts on opposite axial surfaces of the armature 28 , more precisely on opposite surfaces of the webs 43 .

[0072] The spring element 42 faces away from the armature 28 and abuts the shift sleeve 18 .

[0073] Thus, the armature 28 is axially coupled to the shift sleeve 18, and compression of the spring element 42 allows relative axial movement between the armature 28 and the shift sleeve 18. In other words, the armature 28 is removably coupled to the shift sleeve 18.

[0074] In the illustrated embodiment, the spring element 42 is formed by a pack of wave springs.

[0075] To allow the armature 28 to move relative to the shift sleeve 18, the shift sleeve 18 has a circumferential recess 44 into which the web 43 of the armature 28 extends (see FIG. 3).

[0076] Each of the axial end faces of the recesses 44 is provided with a circumferential groove 46, which serves to position the spring elements 42. More specifically, the spring elements 42 are arranged in sections within the grooves 46, respectively, and in the assembled state of the shift sleeve 18, the spring elements 42 are fixed on the grooves 46 so as not to slip off.

[0077] For example, as shown in the cross-sectional view of FIG. 2, the clutch 10 has locking means 47 which include a number of locking elements 48, which in the illustrated embodiment are designed as bolts.

[0078] For example, four circumferentially distributed locking elements 48 are provided (see also FIG. 10).

[0079] The purpose of the locking element 48 is to block, in particular mechanically block, the shift sleeve 18 from moving beyond the disengaged position when the shift sleeve 18 moves from the engaged position in the direction of the disengaged position, as will be explained in more detail below based on the explanation of the operating principle of the clutch 10.

[0080] For this purpose, the locking element 48 is radially movable between a release position (see Figures 2 and 5) and a locking position (see Figures 8 and 9).

[0081] A drive feature 50 is provided on the armature 28 for positively coupling the armature 28 and the locking element 48 (see Figures 2 and 5-9).

[0082] In the illustrated embodiment, the drive feature 50 is a recess 52 inside the armature 28, and the locking element 48 is end-located within the recess 52 in the released position, as shown in FIG.

[0083] In the illustrated embodiment, the driving feature 50 comprises a bevel 54 .

[0084] The locking element 48 is movably guided in the shift sleeve 18 , more precisely in the connecting ring 36 .

[0085] The shift sleeve 18 is provided with a corresponding recess 56 through which the locking element 48 can extend, in particular when the locking element 48 is moved into the locked position.

[0086] In the cross-sectional view of FIG. 4, it can be seen that the clutch 10 further comprises a retaining means 58 .

[0087] The retaining means 58 is designed to retain the shift sleeve 18 in either the disengaged or engaged position when the coils 22, 24 are in a de-energized state.

[0088] For this purpose, the retaining means 58 comprise a number of retaining elements 60 which are attached to the shaft 12 and act elastically on the shift sleeve 18 .

[0089] In the illustrated embodiment, the retaining elements 60 are balls, each of which is disposed in a radial recess 64 in the shaft 12 and partially protrudes from the shaft 12 when the shift sleeve 18 is in the engaged or disengaged position.

[0090] The retaining elements 60 each act in the direction of the shift sleeve 18 by means of a spring element 66 .

[0091] The shift sleeve 18 has three axially spaced recesses 68 in the region of the retaining elements 60. In the engaged or disengaged position of the shift sleeve 18, the retaining elements 60 at least partially project into the corresponding recesses 68.

[0092] As the shift sleeve 18 moves from the disengaged position to the engaged position, the retaining element 60 is forced further into the recess 64 in the shaft 12 against the spring force, allowing axial movement of the shift sleeve 18.

[0093] The retaining element 60 is circumferentially offset relative to the locking element 48, as shown in FIG.

[0094] One of the recesses 68 in which the retaining element 60 engages in the disengaged position of the shift sleeve 18 , in particular the central recess 68 , has a triangular contour when viewed in longitudinal section through the shift sleeve 18 .

[0095] The principle of operation of the clutch 10, and in particular the manner in which the electromagnetic clutch 10 is operated, will now be described with reference to FIGS.

[0096] 4 and 5 show the clutch 10 in a neutral position with the shift sleeve 18 in a disengaged position.

[0097] The locking element 48 is in the release position, the locking element 48 being specifically arranged centrally above the locking tooth 70 .

[0098] The locking tooth 70 is centrally located on a guide surface 72 on the exterior of the shaft 12 .

[0099] The height of the locking teeth 70 is selected so that the locking element 48 is able to move axially over the locking teeth 70 when in the released position, and moves axially against the locking teeth 70 when in the locked position.

[0100] The locking element 48 has, for example, a tooth-shaped tip 73 at the end facing the shaft 12. In other words, the locking element 48 has a flat in the direction of the locking tooth 70.

[0101] The guide surface 72 is formed in particular by partially removing longitudinal teeth of the shaft 12, for example by milling.

[0102] In the neutral position, the armature 28 is centrally located above the shift sleeve 18 and centered between the clutch bodies 14,16.

[0103] When the clutch 10 is shifted, for example by energizing the first coil 22, a magnetic force acts on the armature 28, causing the armature 28 to move to the right in the illustrated embodiment (see FIG. 6).

[0104] The clutch body 14 acts as a stop limiting the path of movement of the armature 28. The movement of the armature 28 causes a corresponding movement of the shift sleeve 18, so that the teeth 34 of the shift sleeve 18 mesh with the internal teeth 26 of the clutch body 14. This movement is achieved by a magnetic force acting on the armature 28, on the one hand, and by a torque acting on the shift sleeve 18, on the other hand.

[0105] 7 specifically illustrates the magnetically induced movement of the shift sleeve 18 just prior to the teeth 34 of the shift sleeve 18 overlapping with the internal teeth 26 of the clutch body 14. The condition illustrated in FIG. 7 may occur initially, where the teeth 34 of the shift sleeve 18 abut against the end face of the clutch body 14 until the internal teeth 26 of the clutch body 14 are aligned. The teeth 34 of the shift sleeve 18 are allowed to engage the clutch body 14 and the energy stored in the spring element 42 causes the shift sleeve 18 to engage with the internal teeth 26 of the clutch body 14.

[0106] When the armature 28 moves so that the shift sleeve 18 overlaps the clutch body 14, the shape of the internal teeth 26 of the clutch body 14 and the teeth 34 of the shift sleeve 18 causes the shift sleeve 18 to be further attracted toward the clutch body 14 until the shift sleeve 18 abuts against the clutch body 14, as shown in Figures 6 and 8.

[0107] 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 engaged position, such that torque transmission between the shaft 12 and the shift sleeve 18 generates a force on the shift sleeve 18 in the direction of the engaged position.

[0108] The movement path of the shift sleeve 18 toward the engaged position is limited by the shift sleeve 18 abutting against the clutch body 14 .

[0109] As can be seen in FIG. 6, one of the spring elements 42 is compressed, particularly the spring element 42 furthest from the clutch body 14 with which the shift sleeve 18 is engaged.

[0110] The retaining element 60 moves into a corresponding recess 68 in the shift sleeve 18 and an additional retaining force acts on the shift sleeve 18 .

[0111] As the shift sleeve 18 moves from the disengaged position shown in FIG. 6 to the engaged position, the locking element 48 moves to the locked position.

[0112] As shown in FIG. 5, when the shift sleeve 18 is in the disengaged position, the locking element 48 is initially in a released position.

[0113] One end of the locking element 48 remote from the shaft 12 engages a drive profile 50 .

[0114] When the coil 22 is energized to move the armature 28 and move the shift sleeve 18 in conjunction with the armature 28 via the spring element 42, the lock element 48 moves together with the shift sleeve 18 since the lock element 48 is attached to the shift sleeve 18, and initially reaches the state shown in FIG. 7.

[0115] The locking element 48 initially remains in the released position, as shown in FIG.

[0116] As the force caused by the torque causes the shift sleeve 18 to move further towards the engaged position, the movement of the shift sleeve 18 causes the locking element 48 to be pulled out of the drive geometry 50 as a stop on the clutch body 14 blocks further movement of the armature 28.

[0117] In this movement, the locking element 48 moves out of the recess 52 and slides along the bevel 54. As a result, the locking element 48 is depressed until it reaches the locked position as shown in FIG.

[0118] The armature 28 can remain in the position shown during the engaged condition.

[0119] The shift sleeve 18 is still held in the engaged position, in particular by the torque and by the holding means 58 .

[0120] To open the clutch 10, the second coil 24 is energized to again move the armature 28 in the disengagement direction until the armature 28 abuts the opposing clutch body 16, as shown particularly in FIG.

[0121] The shift sleeve 18 moves with the armature 28 from the engaged position.

[0122] However, the locking element 48 is still in the locked position, preventing the shift sleeve 18 from returning to the disengaged position.

[0123] More specifically, the locking element 48 abuts the locking tooth 70 .

[0124] In this way, the shift sleeve 18 is first decelerated during the disengagement process, ensuring that undesirable overshoot of the shift sleeve 18 beyond the disengagement position is prevented.

[0125] To return the shift sleeve 18 to the disengaged position, the coil 24 is de-energized and both coils 22, 24 are de-energized, causing the armature 28 to return to its initial position. The movement of the armature 28 is effected by the elastic energy stored in the spring element 42.

[0126] When the armature 28 is moved to the initial position, the recess 52 of the drive shape 50 is positioned above the locking element 48 so that the locking element 48 can return to the released position.

[0127] In particular, the retaining means 58 returns the shift sleeve 18 to the release position. More precisely, when the retaining element 60 acts, it presses against an inclined surface (triangular in longitudinal section) of a recess 68 in the shift sleeve 18. This is shown in the schematic diagram of FIG.

[0128] Because the locking element 48 is no longer held in the locked position, the locking element 48 slides along the locking teeth 70 as the shift sleeve 18 moves and is forced back into the disengaged position.

[0129] The clutch 10 is then again in the initial state.

[0130] In a similar manner, the shift sleeve 18 can be engaged with the clutch body 16. To do this, the armature 28 is moved in the opposite direction by energizing the other coil 22, 24, respectively.

[0131] The mechanical lock function allows the armature 28 to move to its end position by appropriately energizing the coils 22, 24 for each shift operation, thereby shortening the shift time, and in particular, eliminating the need for complex position control.

[0132] Additionally, the position of the armature 28 can be used to indirectly determine the position of the shift sleeve 18 .

[0133] Another embodiment of the clutch 10 will now be described with reference to Figures 12-24.

[0134] The clutch 10 shown in FIGS. 12 to 24 differs substantially from the clutch 10 described above in the attachment of the locking element 48.

[0135] In the following, the same reference numbers are used for the same structures with the same functions as those in the above embodiments, reference is made to the above description in this regard, and the differences between the respective embodiments are described below to avoid repetition.

[0136] Similar to the embodiment described above, the locking element 48 is designed as a radially displaceable bolt which is guided in the connecting ring 36 .

[0137] In contrast to the embodiment described above, however, the locking element 48 is acted upon in the released position by a resilient element 74, which in this embodiment is a spring, as shown in figures 12, 15 and 18.

[0138] The spring element 42 for connecting the armature 28 to the shift sleeve 18 is omitted in this embodiment. In particular, as shown in Figures 14 and 17, which show a longitudinal section of the clutch 10 in the area between the locking element 48 and the retaining means 58.

[0139] Instead, the armature 28 is coupled to the shift sleeve 18 via a locking element 48, as described below.

[0140] The armature 28 is also provided with a drive profile 50 having a recess 52 with a step 76 on either side thereof, so that the recess 52 is deeper in the central region than in the side regions.

[0141] In the central region, the contour of the recess 52 preferably matches the contour of the locking element 48 .

[0142] When the clutch 10 is in a neutral state, i.e., the shift sleeve 18 is in a disengaged position, the elastic element 74 acts on the locking element 48 toward the central deeper region of the drive profile 50 or recess 52, and the armature 28 is removably coupled to the shift sleeve 18.

[0143] In particular, the locking elements 48 are force and form-fittingly coupled to the armature 28 such that as the armature 28 moves, so does the locking elements 48, particularly so long as the locking elements 48 are in the released position. Although the embodiment of Figures 12-19 includes a total of six locking elements 48 (see Figures 8 and 19) distributed circumferentially, the locking elements 48 need not necessarily be evenly spaced circumferentially.

[0144] The holding means 58 is essentially the same as the holding means in the above-described embodiment.

[0145] However, all recesses 68 in the shift sleeve 18 have a triangular cross-section as can be seen in Figures 13 and 16, whereas in the embodiment described above the two outer recesses 68 have a semicircular cross-section.

[0146] The operation of the clutch 10 according to FIGS. 12 to 19 differs only slightly from the operation of the clutch 10 according to FIGS.

[0147] The operation of the clutch 10 is described below with reference to Figures 20 to 24.

[0148] 20 shows the clutch 10 in a neutral condition, with the armature 28 and shift sleeve 18 in a center or disengaged position.

[0149] When the first coil 22 is energized, the armature 28 moves as shown by the rightward arrow in FIG. 20 and the shift sleeve 18 moves with the armature 28 because the armature 28 is coupled to the locking element 48.

[0150] In FIG. 21 the shift sleeve 18 is shown in a position which can be achieved purely by magnetic forces.

[0151] Since the armature 28 is already in contact with the clutch body 14, the armature 28 cannot move further in the engagement direction.

[0152] However, there is already some overlap between the teeth 34 of the shift sleeve 18 and the internal teeth 26 of the clutch body 14 .

[0153] As already explained in connection with the above embodiment, the shift sleeve 18 is pulled further in the direction of the engagement position by the special shape of the teeth with undercuts in the direction of the engagement position and by the acting torque, until it reaches the position shown in FIG. 22.

[0154] During this movement of the shift sleeve 18, the locking element 48 is pulled out of the central region of the drive profile 50 and the locking element 48 is pushed downwards over a step against the spring force of the resilient element 74 into the locked position because the shift sleeve 18 can continue to move and moves relative to the armature 28 while the further movement of the armature 28 is blocked against the clutch body 14.

[0155] The shift sleeve 18 and armature 28 are maintained in the position shown in FIG. 22 by a retaining means 58 unless the coils 22, 24 are energized.

[0156] Release is performed, as in the previous embodiment, by energising the further coil 24, so that the locking element 48 abuts against the locking tooth 70, initially blocking the shift sleeve 18 from returning to the released position (see FIG. 23).

[0157] The armature 28 cannot come to rest against the opposing clutch body 16 because it is held by the drive feature 50 on the locking element 48 .

[0158] To allow the shift sleeve 18 to return to the disengaged position, the armature 28 is again moved to the right by briefly energizing the first coil 2 until the central region of the drive geometry 50 is positioned above the locking element 48, allowing the spring force to move the locking element 48 to the released position.

[0159] 23 to the disengaged position is effected by the retaining elements 60 pressing against the retaining means 58, in particular against the inclined faces of the triangular recesses 68, as already shown in FIG.

[0160] 25 to 27 show another embodiment of the electromagnetic clutch 10. FIG.

[0161] The embodiment shown in FIGS. 25 to 27 is based on the embodiment shown in FIGS.

[0162] However, according to the embodiment shown in figures 25 to 27, the locking element 48 does not have a locking function, but only a coupling function, in particular the locking element 48 couples the armature 28 to the shift sleeve 18 as described above.

[0163] The locking teeth 70 and tips 73 of the locking element 48 are omitted. Instead, the locking means 47 includes a control unit 49 that controls energization of the first coil and the second coil such that, when the shift sleeve moves from the engaged position toward the disengaged position, the shift sleeve is prevented from moving beyond the disengaged position toward another engaged position.

Claims

1. a shift sleeve (18) disposed on the shaft (12), rotating with the shaft (12), and linearly movable along the shaft (12) between a first engaged position, a second engaged position, and a disengaged position located between the first and second engaged positions; a first clutch body (14) and a second clutch body (16) spaced apart from each other in an axial direction and arranged side by side coaxially with the shaft (12), each having internal teeth (26); a stator (20) having energizable first and second coils (22, 24) for directly or indirectly adjusting the shift sleeve (18) along the shaft (12); Equipped with The shift sleeve (18) has first teeth (34) that engage with the internal teeth (26) of the first clutch body (14) in a first engagement position and second teeth (35) that engage with the internal teeth (26) of the second clutch body (16) in a second engagement position; An electromagnetic clutch (10) comprising a locking means (47) that prevents the shift sleeve (18) from moving beyond the disengaged position toward another engaged position when the shift sleeve (18) moves from an engaged position toward a disengaged position.

2. 2. The electromagnetic clutch (10) according to claim 1, characterized in that the locking means (47) comprises a locking element (48) which is a bolt radially movable between a released position and a locked position.

3. 3. The electromagnetic clutch (10) of claim 2, wherein the locking element (48) is biased toward the released position by a resilient element (74).

4. 4. The electromagnetic clutch (10) of claim 3, wherein 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. 5. An electromagnetic clutch (10) according to claim 2, characterized in that the locking element (48) is mounted radially movably within the shift sleeve (18), in particular in that the shift sleeve (18) is split in the middle, the two parts of the shift sleeve (18) are axially fixed to one another by a connecting ring (36), and the locking element (48) is guided radially movably within the connecting ring (36).

6. 6. The electromagnetic clutch (10) according to any one of claims 1 to 5, characterized in that the clutch (10) comprises an armature (28) coupled to the shift sleeve (18), the armature (28) being movable along the shaft (12) by energizing the first or second coils (22, 24) which can be energized of the stator (20).

7. 7. The electromagnetic clutch (10) according to claim 6, wherein the armature (28) is removably coupled in a direction of movement to the shift sleeve (18) by the locking element (48).

8. 7. The electromagnetic clutch (10) according to claim 6, characterized in that the armature (28) is coupled to the shift sleeve (18) via two elastic spring elements (42) abutting axially opposite surfaces of the armature (28) and each having an end remote from the armature (28) abutting the shift sleeve (18).

9. 9. The electromagnetic clutch (10) of claim 7 or 8, characterized in that a drive feature (50) is present on the armature (28) for positively coupling the armature (28) to the locking element (48), the drive feature (50) having a step (76) or a bevel (54) configured such that when the shift sleeve (18) moves relative to the armature (28), movement along the step (76) or the bevel (54) moves the locking element (48) from a released position to a locked position or vice versa.

10. The electromagnetic clutch (10) according to any one of claims 1 to 9, characterized in that a guide surface (72) is present on the outside of the shaft (12), a lock tooth (70) is arranged in the center of the guide surface (72), and the lock element (48) abuts against the lock tooth (70) when moving from the engaged position to the released position.

11. The electromagnetic clutch (10) according to any one of claims 1 to 10, characterized in that the electromagnetic clutch (10) is provided with a holding means (58) configured to hold the shift sleeve (18) in a disengaged or engaged position when the energizable first or second coil (22, 24) is de-energized.

12. 12. The electromagnetic clutch (10) according to claim 11, characterized in that the retaining means (58) comprises at least one retaining element (60) mounted in the shaft (12) and acting elastically on the shift sleeve (18), the shift sleeve (18) having three axially spaced recesses (68) in the region of the retaining element (60), the retaining elements (60) projecting at least partially into the corresponding recesses (68) in the engaged or disengaged position of the shift sleeve (18).

13. 13. The electromagnetic clutch (10) of claim 12, wherein at least one of the recesses (68) has a triangular contour when viewed in a longitudinal cross section of the shift sleeve (18).

14. 14. The electromagnetic clutch (10) according to any one of claims 1 to 13, characterized in that the locking means (47) includes a control unit configured to control energization of the first coil (22) and the second coil (24) such that, when the shift sleeve (18) moves from an engaged position toward a disengaged position, the shift sleeve (18) is prevented from moving beyond a released position toward another engaged position.

15. A method of operating an electromagnetic clutch (10) according to any one of claims 1 to 13, comprising the steps of: - while said shift sleeve (18) is in a disengaged position, said first coil (22) or said second coil (24) is energized, causing said shift sleeve (18) to move in the direction of the corresponding engaged position; - a movement of the locking element (48) in the radial direction from a release position to a locking position during the movement of said shift sleeve (18) from a disengaged position to an engaged position, in particular at the latest when the engaged position is reached; - the locking element (48) blocks the movement of the shift sleeve (18) towards the disengaged position while the further coils (22, 24) are energised to cause the shift sleeve (18) to move from the engaged position towards the disengaged position; The method includes:

16. 16. The method of claim 15, wherein re-energizing the first coil (22) or the second coil (24) that was energized to move the shift sleeve (18) to an engaged position moves the locking element to a released position, allowing the shift sleeve (18) to return to the released position.

17. 16. The method according to claim 15, characterized in that after energising the further coils (22, 24) the energisation is stopped, the armature (28) returns to its initial position and the locking element (48) is allowed to return to its released position.

18. 18. The method according to claim 15, wherein in the electromagnetic clutch (10) according to claim 11, the shift sleeve (18) is reset to the release position by being pressed against an inclined surface of a recess (68) of triangular longitudinal section in the shift sleeve (18) when a holding means (58), in particular a holding element (60), is acted upon.

19. 15. A method of operating an electromagnetic clutch (10) as recited in claim 14, comprising the steps of: - while said shift sleeve (18) is in a disengaged position, said first coil (22) or said second coil (24) is energized, causing said shift sleeve (18) to move in the direction of the corresponding engaged position; a control unit (49) controls energization of the first coil (22) and the second coil (24) after the shift sleeve (18) has moved from an engaged position towards a disengaged position, so that when the shift sleeve (18) has moved from an engaged position towards a disengaged position, the shift sleeve (18) is prevented from moving beyond a released position towards another engaged position.

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