Differential device with disconnect

Abstract

A differential device (10) is provided. The differential device (10) comprises a cage (30), a carrier (40) and a disconnect coupling (50) having radially protruding splines (56a-b) arranged along the entire circumference of the disconnecting coupling (50) and being configured to selectively connect the carrier (40) to the cage (30).

Description

[0001] DIFFERENTIAL DEVICE WITH DISCONNECT

[0002] Technical Field

[0003] The present invention relates to differential devices, and in particular to a solution for disconnecting rotating parts of the differential device from the driveline.

[0004] A differential device is normally arranged on vehicle axle for allowing the wheels of the axle to rotate at different speeds. The differential device comprises a ring gear receiving input drive torque, causing the ring gear to rotate. The ring gear is connected to a carrier which encloses pinion gears, engaging side gears being attached to the respective wheel axles. As the pinion gears can rotate around their respective axis, differential motion of the driven bevel gears is allowed.

[0005] It has been suggested to include a disconnect functionality to the differential in order to disengage the side gears (i.e. the respective wheels) from the transverse ring gear, as well as from an outer case or cage of the differential to which the ring gear is mounted. One such example is described in W02020 178875, where the ring gear is connected to such an outer case or cage. An inner case, i.e. the carrier with the pinion gears and side gears, is connectable with the cage by means of a clutch. The clutch is formed by a cylindrical member being axially moveable relative the cage and having axially standing teeth facing mating axially disposed teeth of the carrier. By engaging the clutch the cylindrical member will move axially, causing the dog teeth to engage thereby connecting the ring gear, via the cage, to the carrier.

[0006] While this prior art document suggests a solution which allows for the desired differential disconnect functionality, the axial engagement / disengagement of the dog teeth will cause a significant and disturbing noise. This is especially due to the engagement of the moveable cylindrical member of the clutch with the cage. Consequently, there is a need for an improved differential device with disconnect functionality which provides for a smoother operation and reduces undesired sounds.

[0007] Summary

[0008] It is an object of the invention to at least partly overcome one or more of the above-identified limitations of the prior art. According to a first aspect, a differential device is provided. The differential device comprises a cage formed by at least two cage parts connected to each other, a carrier, and a disconnect coupling having radially protruding splines configured to selectively connect the carrier to the cage.

[0009] The radially protruding splines may be arranged on an axially moveable dog member.

[0010] The radially protruding splines may be arranged in at least one, preferably two parallel rows.

[0011] The radially protruding splines may be arranged on a first side of the dog member, and wherein the dog member may further comprise a second set of splines on a second side.

[0012] The radially protruding splines may face the carrier and configured to selectively engage with mating splines of the carrier.

[0013] The second set of splines of the dog member may be in constant engagement with mating splines of the cage.

[0014] The dog member may be rigidly attached to a controllable sleeve.

[0015] According to a second aspect a differential device is provided. The differential device comprises a cage, a carrier, and a disconnect coupling having a dog member arranged radially between the carrier and the cage.

[0016] The dog member may be provided with radially protruding splines configured to selectively connect the carrier to the cage.

[0017] According to a third aspect, a vehicle is provided. The vehicle comprises a differential device according to the first or second aspects.

[0018] Brief Description of the Drawings

[0019] Embodiments of the invention will now be described, by way of example, with reference to the accompanying schematic drawings, in which

[0020] Fig. 1 is a cross sectional view of a differential device according to an embodiment;

[0021] Figs. 2a-b are partly cross-sectional views showing the differential device of Fig. 1 in a connected mode;

[0022] Figs. 3a-b are partly cross-sectional views showing the differential device of Fig. 1 in a disconnected mode; and

[0023] Figs. 4a-b are enlarged cross-sectional views of parts of the differential device of Fig. 1.

[0024] Figs. 5a-c are different views of (parts of) the differential device of Fig. 1. Detailed Description

[0025] In Fig. 1 a differential device 10 is shown in cross-section. The differential device 10 comprises a ring gear 20 being securely fixed to a differential cage 30, e.g. by means of bolts 21. In a preferred embodiment the differential cage 30 is actually assembled by connecting two separate parts 30a-b (left and right parts seen in Fig. 1) using the bolts 21. Alternatively, the two or more separate parts 30a-b may be connected by welding. Hence, the ring gear 20 is actually added to the cage 30 when the cage 30 itself is assembled. Hence, the differential cage 30 is formed by connecting two or more parts 30a-b to form the entire differential cage 30.

[0026] In some examples the differential cage 30 is formed by a first part 30a being arranged at a first side of the differential device 30, and a second part 30b being arranged at an opposite side of the differential device 30. The two parts 30a-b may be connected to each other using fasteners such as bolts.

[0027] While the ring gear 20 is shown to have radial gears 22, it should be noted that it would also be possible to provide the ring gear 20 with bevelled gears. The ring gear 20 is configured to receive input torque from a torque source, e.g. an electric motor (not shown).

[0028] The differential cage 30 encloses a carrier 40. The carrier 40 has a cylindrical extension and carries two opposite pinion gears 42, 44. These pinion gears 42, 44 are connected to the carrier 40 by means of a pin 46 extending through the carrier 40. Optionally, it would be possible to accommodate four pinion gears inside the carrier, e.g. for the purpose of increasing the torque capability of the differential device 10.

[0029] The pinion gears 42, 44 are in engagement with two opposite side gears

[0030] 48, 49. Each of the side gears 48, 49 is connected to a respective wheel axle (not shown).

[0031] The carrier 40, as well as the pinion gears 42, 44 and the side gears 48,

[0032] 49, may be arranged inside the differential cage 30 such that the arrangement of the carrier 40, pinion gears 42, 44, and side gears 48, 49 is asymmetric with regards to the first and second cage parts 30a, 30b. Hence, one cage part 30a, 30b may extend across the centre line of the carrier 40, pinion gears 42, 44, and side gears 48, 49 while the other cage part 30a, 30b does not extend across the same centre line.

[0033] The carrier 40 is selectively connected to the differential cage 30 by means of a disconnect coupling 50. The disconnect coupling 50 comprises an axially displaceable sleeve 52 arranged radially outside the differential cage 30. The disconnect coupling 50 further comprises a cylindrical dog member 54 being fixed to the sleeve 52, such that axial movement of the sleeve 52 causes a corresponding axial movement of the dog member 54. The dog member 54 may be rigidly attached to the sleeve 52. In some examples, the dog member 54 is arranged inside the differential cage 30, preferably accommodated fully by one of the first or second cage part 30a, 30b. hence, the differential cage 30 may comprise an opening through which the sleeve 52 can connect to the dog member 54.

[0034] An actuator (not shown) is provided for controlling the disconnect device 50. Preferably, the actuator is an electromechanical actuator having an eccentric pin inserted into a slot of the sleeve 52. Upon actuation, the actuator will cause the pin to rotate, thereby causing it to move also axially due to the eccentric configuration. Maximum translation of the sleeve 52 can thus be achieved by rotating the pin ±90°, or less.

[0035] It should however be noted that other actuators may replace the above- mentioned example utilizing the eccentric pin; as possible option, a solenoid, a ball ramp mechanism, or a hydraulic piston could be considered for controlling the disconnect device 50.

[0036] The dog member 54 is arranged radially between the carrier 40 and the cage 30. The dog member 54 has outer splines 55 engaging with mating splines 31 on the inner surface of the cage 30. The inner splines 31 of the cage 30 may be arranged along the entire circumference of cage 30. Preferably, the inner splines 31 are arranged centrally on an inner surface of the cage 30, leaving outer axial regions of the inner surface free of splines. In case the cage 30 is formed by two or more parts 30a-b, the mating splines 31 of the inner surface of the cage 30 may be arranged on one part 30a-b only.

[0037] The dog member 54 is further provided with inner splines 56a-b selectively engaging with mating outer splines 41a-b of the carrier 40.

[0038] Now turning to Figs. 2a-b, the differential device 10 is shown in a state where the disconnect coupling 50 is connected, i.e. the carrier 40 is rotationally connected to the cage 30.

[0039] In Fig. 2a the outer surface of the dog member 54 is shown. The outer splines 55 has an axial extension exceeding the maximum axial distance by which the dog member 54 is moveable. Hence the splines 55, protruding radially out from the dog member 54, will always be in engagement with the inner splines In Fig. 2b the outer surface of the carrier 40 is shown. Two rows of splines 41a-b are arranged at the lateral ends of the carrier 40. The splines 41a-b protrude radially and engages with the corresponding inner rows of splines 56a-b of the dog member 54. As mentioned above, it would be possible to use other number of spline rows, such as only one spline row, three spline rows, etc.

[0040] The splines 56a-b are arranged along the circumference of the dog member 54, and the splines 41a-b are arranged along the circumference of the carrier 40. The splines 56a-b may be equally distanced (i.e. continuously arranged along the entire circumference) or they may be arranged group-wise in segments along the entire circumference.

[0041] Now turning to Figs. 3a-b, the differential device 10 is shown in a state where the disconnect coupling 50 is disconnected, i.e. the carrier 40 is free to rotate relative to the cage 30.

[0042] In Fig. 3a the outer surface of the dog member 54 is shown, i.e. this figure corresponds to Fig. 2a however the sleeve 52 and the dog member 54 have been axially moved to the right. The outer splines 55 of the dog member 54 are still in engagement with the inner splines 31 of the cage 30.

[0043] In Fig. 3b the outer surface of the carrier 40 is shown, i.e. this figure corresponds to Fig. 2b however the sleeve 52 and the dog member 54 have been axially moved to the right. The two rows of splines 56a-b have been axially displaced so they are no longer engaging with the outer splines 41a-b of the carrier 40.

[0044] Cross-sectional views of the disconnect coupling 50 are given by Figs. 4a- b. As is clear from Fig. 4a, showing the connected state of the disconnect coupling 50, the sleeve 52 is moved to the left to reach its end position, which corresponds to a position of the dog member 54 where the spline rows 56a-b are engaging with the rows of splines 41a-b of the carrier 40.

[0045] In Fig. 4b the sleeve 52 is moved to the right to reach its opposite end position, which corresponds to a position of the dog member 54 where the spline rows 56a-b are axially moved out of contact with the rows of splines 41a-b of the carrier 40.

[0046] Although the invention has been described with reference to the specific example shown in the figures, it should be noted that in some embodiments it would be possible to arrange the splines 55, 56a-b of the dog member 54 in an opposite manner, i.e. so that the dog member 54 is always connected with the carrier 40 while selective connection is instead established with the cage 30. Such configuration would then require the outer spline configuration of the carrier to be repositioned to the inner side of the cage 30, and vice versa. Since in the shown example the dog member 54 is extending through the cage 30, an opposite configuration would also require further modifications of the structural construction of the differential device 10.

[0047] In Figs. 5a-c the differential device 10 is shown further. Starting in Fig. 5a, the differential device 10 is shown in cross-section with specific focus on the cage 30. In Fig. 5a the carrier is left out, thereby showing the internal splines 31 of the cage 30. As is clear from this figure, the internal splines 31 are only provided on the right part of the cage 30.

[0048] In Fig. 5b the differential device 10 is shown with the carrier 40 hidden beneath the dog member 54 of the disconnect coupling 50.

[0049] In Fig. 5c the entire differential device 10 is shown except for the ring gear. Here it can be seen that the left part of the cage 30 is covering the dog member 54 of the disconnect coupling 50, while the sleeve 52 is arranged radially outside the cage 30.

[0050] From the description above follows that, although various embodiments of the invention have been described and shown, the invention is not restricted thereto, but may also be embodied in other ways within the scope of the subjectmatter defined in the following claims.

Claims

CLAIMS1. A differential device (10), comprising a cage (30), a carrier (40) and a disconnect coupling (50) having radially protruding splines (56a-b) arranged along the entire circumference of the disconnecting coupling (50) and being configured to selectively connect the carrier (40) to the cage (30).

2. The differential device (10) according to claim 1, wherein the radially protruding splines (56a-b) are arranged on an axially moveable dog member (54).

3. The differential device (10) according to claim 2, wherein the radially protruding splines (56a-b) are arranged in at least two parallel rows.

4. The differential device (10) according to claim 2 or 3, wherein the radially protruding splines (56a-b) are arranged on a first side of the dog member(54), and wherein the dog member (54) further comprises a second set of splines(55) on a second side.

5. The differential device (10) according to claim 4, wherein the radially protruding splines (56a-b) are facing the carrier (40) and configured to selectively engage with mating splines (41a-b) of the carrier (40).

6. The differential device (10) according to 4 or 5, wherein the second set of splines (55) of the dog member (54) are in constant engagement with mating splines (31) of the cage (30).

7. The differential device (10) according to any of claims 2-6, wherein the dog member (54) is rigidly attached to a controllable sleeve (52).

8. A differential device (10), comprising a cage (30), a carrier (40), and a disconnect coupling (50) having a dog member (54) arranged radially between the carrier (40) and the cage (30).

9. The differential device (10) according to claim 8, wherein the dog member (54) is provided with radially protruding splines (56a-b) configured to selectively connect the carrier (40) to the cage (30).

10. A vehicle, comprising a differential device (10) according to any of claims 1 to 9.5

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