Electromagnetically actuated tool clutch and method for mounting a shift sleeve of an electromagnetically

Abstract

An electromagnetically actuated dog clutch includes: a shift sleeve having internal teeth and axially movably received on external teeth of a driveshaft for common rotation therewith; an actuator having a magnetic coil and adapted to axially move the shift sleeve on the driveshaft to a first shift position; a spring element cooperating with the shift sleeve and acting on the shift sleeve in the direction of the second shift position in the opposite direction to the movement caused by the actuator; and a support ring inserted on the transmission shaft and arranged between the spring element and the inner teeth of the shift sleeve in the axial direction of the shift sleeve. The support ring is connected to the driveshaft with respect to an axial direction. In order to mount the shift sleeve to the driveshaft, an assembly is formed by arranging a support ring and a spring element on the shift sleeve, and the assembly is pushed onto the outer teeth of the driveshaft until a predetermined end position of the support ring is reached, at which the support ring is fixed to the driveshaft.

Description

Technical Field

[0001] The invention relates to an electromagnetically actuated dog clutch having a shift sleeve and a method for mounting a shift sleeve of an electromagnetically actuated dog clutch on a transmission shaft. Background Art

[0002] In an electromagnetically actuated dog clutch, the shift sleeve is usually electromagnetically attracted to one of the two shift positions by a magnetic field generated by a coil and is biased to the other shift position by a spring. The spring must therefore be positioned within the clutch assembly and supported by the reaction force.

[0003] The object of the present invention is to reduce the space required for an electromagnetically actuated dog clutch, in particular in the radial direction, while also making it easier to install. Summary of the invention

[0004] The object is achieved by an electromagnetically actuated dog clutch, which comprises: a shift sleeve having internal teeth and being axially movably received on the external teeth of a transmission shaft for co-rotation therewith; an actuator having a magnetic coil and being configured to be suitable for axially moving the shift sleeve on the transmission shaft to a first shift position; a spring element, which cooperates with the shift sleeve and acts on the shift sleeve in the direction of the second shift position in a direction opposite to the movement caused by the actuator; and a support ring, which is inserted on the transmission shaft and is arranged in the axial direction of the shift sleeve between the spring element and the internal teeth of the shift sleeve and is firmly connected to the transmission shaft relative to the axial direction.

[0005] Since the support ring is fastened directly to the drive shaft, a radially very compact assembly is achieved which can be installed, for example, by simply pressing it axially onto the drive shaft.

[0006] The external teeth of the transmission shaft are formed on a known clutch body, for example, which is connected to the transmission shaft for rotation therewith, and an idler gear having external teeth to be coupled is arranged axially adjacent to the clutch body. The idler gear and the transmission shaft are adapted to be connected for rotation therewith by means of the internal teeth of a shift sleeve engaging in its external teeth, thereby shifting the corresponding gears.

[0007] The dog clutch is preferably designed as a normally open clutch, so that the first shift position corresponds to the closed position of the dog clutch and the second shift position corresponds to its open position. However, the principle of the invention can also be implemented with a normally closed dog clutch.

[0008] The support ring has a contact surface for the spring element that counteracts the forces transmitted by the shift sleeve and forms a reaction surface for the spring element that points in the axial direction.

[0009] The support ring is, for example, an axially rigid metal ring and is a component that is always separated from the transmission shaft and its external teeth. Preferably, the support ring has sufficient elasticity in the radial direction to be pushed onto the external teeth of the transmission shaft. Typically, the support ring can be made of a spring material to prevent plastic deformation as much as possible.

[0010] The spring element consists, for example, of a plurality of spiral springs which are arranged axially adjacent to one another on an external toothing of the drive shaft.

[0011] In a preferred variant, the shift sleeve consists of a plurality of parts which are firmly connected to each other. For example, the shift sleeve has an engagement ring on which an internal tooth is formed, and a shift ring which is firmly connected to the engagement ring and cooperates with the actuator, the shift ring being radially arranged on the outside of the engagement ring, and the support ring being axially arranged next to the engagement ring. In this way, the spring element and the support ring can be easily integrated into a prefabricated assembly for mounting the shift sleeve. In addition, it is therefore easy to realize, for example, a shift sleeve made of a plurality of different materials having different magnetic and mechanical properties.

[0012] In particular, the shift ring should consist of a ferromagnetic material to be suitable for being moved by the actuator. In a preferred variant, the magnetic field of the actuator generates a magnetic drag force in the shift ring, which pulls the shift sleeve closer to the actuator to maximize the inductance in the magnetic circuit.

[0013] The shift sleeve preferably has a receptacle for the support ring and the spring element. For this purpose, the shift ring can extend axially above the support ring and the spring element, that is, the shift ring can be arranged radially outside the support ring and the spring element. In addition, the support ring should have a lateral axial stop for the spring element, which connects the spring element to the shift sleeve and transmits the spring force of the spring element to the shift sleeve. The spring element is preferably arranged between the axial stop and the support ring and is axially clamped between these components.

[0014] The support ring can be radially shorter than the engagement ring and radially spaced from the shift ring. In this way, the magnetic flux from the shift ring to the support ring can be reduced. Since the support ring does not contribute to the shifting force, it is preferably made of a non-ferromagnetic material.

[0015] The internal toothing of the shift sleeve has, for example, a plurality of radial stop projections, each of which cooperates with a stop groove in the external toothing of the transmission shaft and defines the end position of the shift sleeve in the second shift position of the dog clutch. For example, some of the teeth of the internal toothing each have a radial projection, which is axially positioned so as to rest against an axial end of the associated stop groove when the shift sleeve is in the second shift position.

[0016] The stop projection, which is in contact with the end face of the idler gear in the first shift position, can serve to limit the shifting path in the first shift position and thus define the first shift position.

[0017] The magnetic coil of the actuator can be enclosed by an annular actuator housing which, together with the shift ring, forms the magnetic circuit of the actuator.

[0018] The support ring preferably has a resting surface for the shift sleeve, on which a geometric structure is formed, which reduces the contact between the shift sleeve and the support ring. The structure should be designed to reduce adhesion forces, for example due to an oil film and / or magnetic forces between the support ring and the shift sleeve. For example, the cross section of the support ring in the axial direction can have an L-shape, or have protrusions distributed in the radial direction and / or in the circumferential direction. The surface of the shift sleeve that contacts the resting surface is, for example, the side surface of the coupling ring.

[0019] The above object is also achieved by a method for mounting a shift sleeve of an electromagnetically actuated dog clutch on a transmission shaft as described above. To this end, the following steps are performed:

[0020] The support ring and the spring element are arranged on the shift sleeve to form an assembly, and

[0021] The assembly is pushed onto the external toothing of the transmission shaft until a predetermined end position of the support ring is reached, at which the support ring is axially fixed on the transmission shaft.

[0022] To manufacture the assembly, the coupling ring, the support ring and the spring element can be axially aligned before the shift ring is placed radially above these elements and welded to the coupling ring. In this way, a receiving portion is formed and the support ring and the spring element are arranged in the receiving portion at the same time. The support ring and the spring element can therefore be easily preassembled on the shift sleeve so that they can be operated together as a single component. Then it is only necessary to push the assembly to the desired axial position on the external teeth of the transmission shaft. Initially, the support ring usually rests against the side of the coupling ring and is pushed onto the transmission shaft by the coupling ring.

[0023] The above-mentioned radial stop projection and the stop groove can define a predetermined end position of the support ring. When the assembly is pushed onto the external toothing of the transmission shaft, the sliding movement stops when the stop projection comes to rest against the axial end of the stop groove. The support ring thus reaches its correct axial position on the transmission shaft without any further action. Tolerances in the assembly are thus also automatically compensated.

[0024] In the predetermined end position, the support ring is automatically axially fixed on the drive shaft, preferably without any further work steps.

[0025] In order to fix the support ring on the drive shaft, the support ring can be held in a predetermined end position solely by the friction forces on the drive shaft. For this purpose, closed support rings are used in particular. This has the advantage that the support ring does not create any imbalance. This variant is therefore particularly suitable for high speeds.

[0026] When the dog clutch is shifted, the support ring is pushed onto the drive shaft with an axial force greater than the axial force applied by the actuator, so that the support ring does not shift during normal operation of the clutch.

[0027] If necessary, the pushing can be assisted by heating, which causes a temporary radial expansion of the support ring, so that the support ring can be moved to a predetermined end position on the drive shaft. When cooling, the support ring contracts again and is thus firmly clamped on the drive shaft.

[0028] In another variant, the support ring is fixed on the drive shaft by the support ring engaging in a radial groove in the external toothing of the drive shaft in a predetermined end position. In this case, the support ring is slotted so that it can be expanded sufficiently in the radial direction to be pushed onto the drive shaft until it reaches the radial groove. This variant is particularly suitable for low speeds.

[0029] In order to simplify the installation of the components, in particular to push the support ring onto the drive shaft, the support ring is preferably pushed onto a chamfer at one axial end of the external toothing of the drive shaft, thereby expanding radially. The chamfer can be formed at the axial end of the toothing of the external toothing of the drive shaft. When the support ring is pushed onto the drive shaft, the chamfer simultaneously centers the support ring correctly on the drive shaft. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] The invention will be described in more detail below based on an exemplary embodiment and with reference to the accompanying drawings, in which:

[0031] Figure 1 A schematic exploded view showing the components of an electromagnetically actuated dog clutch according to the invention before being mounted on a transmission shaft using the method according to the invention;

[0032] Figure 2 and Figure 3 Shows Figure 1 Schematic perspective, partial cross-sectional views of a dog clutch in an open position and a closed position;

[0033] Figure 4 and Figure 5 Shows Figure 1 A schematic cross-sectional view of a dog clutch in an open position and a closed position;

[0034] Figure 6 Shows Figure 1 A schematic side view of a dog clutch;

[0035] Figure 7 and Figure 8 Shows Figure 1 A schematic cross-sectional view of a dog clutch in an open position and a closed position;

[0036] Fig. 9 The shift sleeve is shown during installation on the transmission shaft. Figure 1 Another schematic cross-sectional view of a tooth clutch;

[0037] Figures 10 to 12 Shows Figure 1 Schematic cross-sectional views of different variations of a support ring for a dog clutch; and

[0038] Fig.13 and Fig.14 Schematic top views of different variants of support rings are shown.

[0039] For the sake of clarity, all identical components are not always provided with reference numerals. DETAILED DESCRIPTION

[0040] Figures 1 to 8 An electromagnetically actuated dog clutch 10 is shown, comprising a shift sleeve 12 which is received on a transmission shaft so as to be movable in an axial direction A and which is also received for co-rotation with a transmission shaft 14 in a circumferential direction U of the transmission shaft. The shift sleeve 12 has internal teeth 16, while the transmission shaft 14 is provided with matching external teeth 18.

[0041] like Figures 2 to 6 It can be seen that the shift sleeve 12 is surrounded in the radial direction r by an actuator 20, which comprises a magnetic coil 22 to which electricity can be supplied and an actuator housing 24. Figure 6 As shown, a current supply is provided to the magnetic coil 22 via a suitable electrical connection 26 .

[0042] When the actuator 20 is activated, the magnetic force F M Acting on the shift sleeve 12 and moving it into a first shift position, which in this example corresponds to the closed position of the dog clutch 10. Figure 3 , Figure 5 and Figure 8 shown.

[0043] The shift sleeve 12 consists of an engagement ring 28 and a shift ring 30, which is arranged radially on the outside of the engagement ring 28 and is fixedly connected to the engagement ring. The internal teeth 16 are only present on the engagement ring 28. The radial inner side of the shift ring 30 is designed to be smooth. The shift ring 30 has a radial protrusion 34 at its first axial end 32 facing away from the engagement ring 28, which extends in the direction toward the transmission shaft 14.

[0044] Between the radial projection 34, the radial inner side of the shift ring 30 and the side surface 36 of the coupling ring 28, a receiving portion 38 is formed, in which a support ring 40 and a spring element 42 are received, which support ring and spring element each have an annular design and are pushed onto the transmission shaft 14 (see, for example, Figure 7 and Figure 8 ).

[0045] The support ring 40 is securely fixed axially and optionally also in the circumferential direction U to the transmission shaft 14 at a predetermined end position.

[0046] The spring element 42 can be compressed in the axial direction A by the movement of the shift sleeve 12 and can be relaxed to axially move the shift sleeve 12 back from the first shift position to the second shift position. The second shift position corresponds to the open position of the dog clutch 10 in this context and is Figure 2 , Figure 4 and Figure 7 Shown in.

[0047] The radial projection 34 forms an axial stop 44 for the spring element 42 , which stops the restoring force F generated by the spring element 42 . R The spring element 42 rests on the side opposite the axial stop 44 against the side of the support ring 40 which forms a second axial stop for the spring element 42 and absorbs the reaction force of the spring element 42 and distributes it into the transmission shaft 14.

[0048] A corresponding radial stop projection 46 is formed on some of the teeth of the inner teeth 16 of the engagement ring 28 of the shift sleeve 12, and the stop projection 46 is distributed on the circumference of the shift sleeve 12 so as to engage with the stop groove 48 (see Figure 1 , Figure 7 and Figure 8 The axial depth of the stop groove 48 and the axial position of the stop projection 46 limit the axial movement of the shift sleeve 12 in the direction of the second shift position, and thus also define the axial position of the second shift position.

[0049] The first shift position is determined here by the stop projection 46 coming to rest against the end face of the idler gear 66 .

[0050] In the second shift position, the shift sleeve 12, more precisely the side face 36 of the engagement ring 28, is in contact with the rest surface 58 of the support ring 40 pointing in the axial direction. In order to reduce the adhesion forces between these two components (which are generated by the oil film and / or magnetic forces between the side face 36 and the rest surface 58), the rest surface 58 can include one or more geometric structures 60 which minimize the contact between the side face 36 and the rest surface 58 as much as possible. Variants thereof are Fig.11 and Fig.12 It is shown in Fig.10 A simple flat support ring 40 is shown.

[0051] exist Fig.11 In the example of , the rest surface 58 is L-shaped in cross section in the radial direction r along the axial direction A, so that only a narrow ring is in contact with the side surface 36 of the engagement ring 28 .

[0052] exist Fig.12 In the example of , a plurality of axial protrusions 62 are formed at different positions of the rest surface 58 with respect to the radial direction r and / or the circumferential direction U, and the rest surface 58 is in contact with the side surface 36 only in the region of the protrusions 62 .

[0053] During operation of the electromagnetic dog clutch 10, the actuator 20 is energized when the dog clutch 10 is about to close. The magnetic field of the magnetic coil 22 generates a magnetic resistance force F in the shift ring 30. M , the magnetic resistance force pulls the shift ring radially under the actuator housing 24 to form a magnetic circuit that is as closed as possible and to maximize the total inductance. Therefore, the shift sleeve 12 moves in the direction of the first shift position until the shift sleeve 12 reaches the first shift position.

[0054] In this position, the internal teeth 16 of the engaging ring 28 of the shift sleeve 12 have been axially moved into engagement with the external teeth 64 of the idler gear 66, which is axially arranged directly adjacent to the external teeth 18 of the transmission shaft 14, and the external teeth 18 of the transmission shaft 14 are coupled to the external teeth 64 of the idler gear 66, so that the transmission shaft 14 and the idler gear 66 are connected to each other for common rotation.

[0055] Due to the displacement of the shift sleeve 12 , the spring element 42 is compressed between the support ring 40 and the axial stop 44 at the projection 34 of the shift ring 30 and builds up a restoring force F R .

[0056] If the dog clutch 10 is to be opened again, the energization of the magnetic coil 22 of the actuator 20 is terminated. The force F generated by the magnetic field M The shift sleeve 12 stops immediately and is restored by the restoring force F exerted by the spring element 42 RThe drive shaft 14 and the idler gear 66 are axially pushed back to the second shift position in the opposite direction. The axial displacement ends in the second shift position when the stop projection 46 comes to rest against the axial end of the stop groove 48. The internal teeth 16 of the engagement ring 28 then disengage from the external teeth 64 of the idler gear 66, so that the transmission shaft 14 and the idler gear 66 are separated again.

[0057] In order to mount the shift sleeve 12 on the external toothing 18 of the transmission shaft 14, the assembly 67 is first formed. For this purpose, the coupling ring 28, the support ring 40 and the spring element 42 are arranged axially adjacent to each other. The shift ring 30 is placed radially on the outside of the coupling ring 28 and is fixed on the outside (for example by welding). The receiving portion 38 is thus formed between the side surface 36 of the coupling ring 28 and the radial projection 34 of the shift ring 30, and the support ring 40 and the spring element 42 are simultaneously accommodated in the receiving portion 38 (see Figure 1 and Fig. 9 ).

[0058] The assembly 67 is now pushed as a whole onto the external teeth 18 of the transmission shaft 14 in the axial direction A. This movement is caused by the inclined surface 68 (see Figure 1 and Fig. 9 ) is supported. The inclined surface 68 centers the support ring 40 and expands it radially so that it can be pushed onto the external toothing 18 under radial tension. During this movement, the support ring 40 moves in the axial direction A via the side surface 36 of the coupling ring 28. The movement ends when the stop projections 46 on the internal toothing 16 of the coupling ring 28 reach the axial end of the corresponding stop groove 48. The support ring 40 is now in its predetermined end position. Due to the mounting carried out in this way, the predetermined end position is precisely aligned with the position of the shift sleeve 12 in the direction of the second shift position at the end of the shift stroke.

[0059] exist Fig.13 In the first variant shown, the support ring 40 is closed in the circumferential direction U. In this case, the support ring 40 is fixed to the drive shaft 14 purely by friction. For example, the mounting can be supported by heating the component, thereby causing a temporary expansion of the support ring 40 in the radial direction r.

[0060] exist Fig.14 In the second variant shown, the support ring 40 is open in the circumferential direction U, i.e. it is slotted, which makes it easier to expand the support ring 40 when it is pushed onto the transmission shaft 14. In this case, the external toothing 18 of the transmission shaft 14 has radial grooves 70 at predetermined end positions of the support ring 40 (e.g. Fig. 9 As shown), the support ring 40 is snapped into the radial groove.

Claims

1. An electromagnetically actuated dog clutch (10), comprising: A shift sleeve (12) having internal teeth (16) and being axially movably received on external teeth (18) of a transmission shaft (14) so ​​as to rotate together with the external teeth of the transmission shaft; an actuator (20) having a magnetic coil (22) and being configured to axially move the shift sleeve (12) on the transmission shaft (14) to a first shift position; a spring element (42) cooperating with the shift sleeve (12) and acting on the shift sleeve (12) in the direction of a second shift position in a direction opposite to the movement caused by the actuator (20); and a support ring (40) inserted on the transmission shaft (14) and arranged between the spring element (42) and the internal teeth (16) of the shift sleeve (12) in an axial direction (A) of the shift sleeve (12) and being firmly connected to the transmission shaft (14) relative to the axial direction (A).

2. The dog clutch (10) according to claim 1, wherein: The shift sleeve (12) has an engagement ring (28) and a shift ring (30), on which the internal toothing (16) is formed and which is firmly connected to the engagement ring (28) and interacts with the actuator (20), wherein the shift ring (30) is arranged radially outside the engagement ring (28) and the support ring (40) is arranged axially adjacent to the engagement ring (28).

3. The dog clutch (10) according to claim 2, wherein: The shift sleeve (12) has a receptacle (38) for the support ring (40) and the spring element (42), wherein the shift ring (30) extends axially above the support ring (40) and the spring element (42) and has a lateral axial stop (44) for the spring element (42).

4. A dog clutch (10) according to any one of the preceding claims, wherein: The internal toothing (16) of the shift sleeve (12) has a plurality of radial stop projections (46), which each interact with a stop recess (48) in the external toothing (18) of the drive shaft (14) and define an end position of the shift sleeve (12) in the second position of the dog clutch (10).

5. The dog clutch (10) according to claim 4, wherein: In the first shift position, the stop protrusion (46) contacts the end surface of the idler gear (66).

6. A dog clutch (10) according to any one of the preceding claims, wherein: The support ring (40) has a rest surface (58) for the shift sleeve (12), and a geometric structure (60) is formed on the rest surface, which reduces the contact between the shift sleeve (12) and the support ring (40).

7. A method for mounting a shift sleeve (12) of an electromagnetically actuated dog clutch (10) according to any one of the preceding claims on a transmission shaft (14), the method comprising the following steps: An assembly (67) is formed by arranging a support ring (40) and a spring element (42) on the shift sleeve (12), and The assembly (67) is pushed onto the external teeth (18) of the transmission shaft (14) until a predetermined end position of the support ring (40) is reached, at which the support ring (40) is axially fixed on the transmission shaft (14).

8. The method according to claim 7, wherein: The support ring (40) is held in the predetermined end position on the drive shaft (14) solely by friction.

9. The method according to claim 7, wherein: In the predetermined end position, the support ring (40) engages in a radial groove (70) in the external toothing (18) of the drive shaft (14).

10. The method according to any one of claims 7 to 9, wherein: The support ring (40) is pushed onto a chamfer (68) at an axial end of the external toothing (18) of the drive shaft (14) and is thereby radially expanded.

Images