WO2016035129A1

WO2016035129A1 - Differential device

Info

Publication number: WO2016035129A1
Application number: PCT/JP2014/072996
Authority: WO
Inventors: 豊史丸山; 博保古川; 康雄山中; 秀之猪瀬
Original assignee: Ｇｋｎドライブラインジャパン株式会社
Priority date: 2014-09-02
Filing date: 2014-09-02
Publication date: 2016-03-10

Abstract

A differential device (1) is provided with: a differential case (3) with a wall section (31) and a trunnion (35); a clutch (7) that is combined with a differential gear set (5); a plunger (9) that is slidably fitted on the trunnion (35) and can move in the axial direction from a first position that allows disengagement of the clutch (7) to a second position for engaging the clutch (7), the plunger (9) being equipped with a first portion (93), which is obtained from a nonmagnetic material, fits slidably around the trunnion (35), has tabs (95) for pressing the clutch (7), and is sized so as not to contact the wall section in the second position, and a second portion (91), which is obtained from a magnetic material, is fixed to the outer circumference of the first portion (93), and is sized so as to contact the wall section in the second position; and a solenoid (13), which is slidably fitted on the outer circumference of the second portion (91) and is for generating magnetic flux to move the second portion (91) in the axial direction.

Description

Differential equipment

The present invention relates to a differential device that engages and disengages a clutch using a solenoid, and more particularly to a differential device that can improve the strength of a differential case by a special plunger configuration.

Automobiles usually use a differential device for the purpose of absorbing the difference in rotation between the left and right axles. In some cases, a clutch is incorporated in the differential device, and a solenoid actuator is used to operate the clutch. In the solenoid actuator, a plunger including a magnetic material is driven by a magnetic force, and when the plunger presses a clutch member, the clutch is connected and disconnected. It is known that a differential device combined with a solenoid actuator can achieve both reliability and compactness.

In order to use the magnetic flux generated by the solenoid with high efficiency, the magnetic circuit is composed of a core made of a material having high permeability. Patent Document 1 discloses a related technique.

Japanese Patent Publication No. 2007-92990

In the configuration disclosed in Patent Document 1, the design of the differential case is restricted by the arrangement of solenoids, and it is difficult to give priority to strength. For example, the plunger outside the differential case operates the internal clutch, but the wall of the differential case that separates the plunger cannot necessarily be made too thick. The wall portion must have a through-hole through which the plunger claw passes. These factors are factors that reduce the strength of the differential case. If the solenoid or plunger is made compact, the trunnion portion that supports the plunger must be thin. This is also a factor that reduces the strength of the differential case.

However, according to studies by the present inventors, contrary to expectations, these do not significantly affect the strength of the differential case, and in contrast, the shape of the skirt of the trunnion is a more dominant factor. found. More specifically, the strength of the differential case increases significantly as the transition from the trunnion portion to the wall portion becomes more gradual. That is, it has been found that if the configuration of the differential case, the solenoid and the plunger can make such a skirt shape possible, it can greatly contribute to the strength improvement. The present invention has been made on the basis of such discoveries concerning the root of the strength problem.

According to one aspect of the present invention, a differential device includes a wall portion that is rotatable about an axis and extends in a radial direction with respect to the axis, and a trunnion that extends in an axial direction from the wall portion. A differential case, a differential gear set that is housed in the differential case and rotates together, a clutch combined with the differential gear set, and a slidably fitted to the trunnion so that the clutch can be disconnected. A plunger which is movable in the axial direction from a first position to a second position where the clutch is connected, and which is made of a nonmagnetic material and is slidably fitted around the trunnion and presses the clutch A first portion dimensioned so as not to contact the wall portion in the second position, and made of a magnetic material, and fixedly attached to an outer periphery of the first portion A plunger having a second portion dimensioned to abut against the wall at the second position, and a slidably fitted to an outer periphery of the second portion; And a solenoid for generating a magnetic flux that moves the portion in the axial direction.

FIG. 1 is a cross-sectional view of a differential apparatus according to an embodiment of the present invention. FIG. 2 is a cross-sectional view of the case body of the differential device. FIG. 3 is a side view of the case body. FIG. 4 is a side view of the plunger as viewed from the clutch side. FIG. 5 is a cross-sectional view of the plunger mainly showing the claw portion. FIG. 6 is an exploded perspective view of the plunger. FIG. 7 is a partial cross-sectional view of the differential device mainly showing the solenoid and the plunger.

Several exemplary embodiments of the present invention are described below with reference to the accompanying drawings.

The embodiment will be described by taking a bevel gear type lock-up differential device as an example, but the embodiment of the present invention is not necessarily limited thereto. The present embodiment can be diverted to other differential devices such as a free running differential device. Further, although an example in which the differential device is applied to an axle is given, it may be applied to another shaft such as a propeller shaft. Further, in the following description, the right and left are only for convenience, and the present embodiment does not depend on the direction.

Referring to FIG. 1, a differential device 1 drives a differential case 3 rotatable around an axis, a differential gear set 5 accommodated in the differential case 3, a clutch 7, a plunger 9 for operating the clutch 7, and the plunger 9. And a solenoid 13 for performing.

The differential case 3 includes a case main body 21 and a cover body 23 covering one end thereof. The case main body 21 and the cover body 23 each have a boss portion protruding in the axial direction, and the boss portion is rotatably supported by the carrier via a bearing, so that the differential case 3 is rotatable around its axis. is there. Normally, the differential case 3 rotates by receiving torque from the engine / motor of the vehicle, and the differential gear set 5 and the clutch member 71 housed therein rotate together with the differential case 3.

Referring to FIG. 2 in combination with FIG. 1, when the cover body 23 is removed, an opening 25 is opened at the right end of the case body 21, and the differential gear set 5 and the clutch member 71 are assembled through the opening 25.

For example, in the case of a bevel gear type, the differential gear set 5 includes a plurality of pinion gears 51 and a pair of

side gears

53 and 55 meshed with the pinion gears 51. The case main body 21 includes a plurality of through holes 27, into which pinion shafts are respectively inserted, and the pinion gear 51 is rotatably supported by the pinion shafts. The

side gears

53 and 55 are supported by races 29 formed on the case body 21 and the cover body 23, respectively, and can be rotated independently. The

side gears

53 and 55 mesh with the pinion gear 51 and are coupled to the right axle and the left axle, respectively, and differentially distribute the torque received from the pinion gear 51 to both axles.

The clutch member 71 is disposed in the differential case 3 so as to face the right side gear 53, and is slidably fitted to a boss portion of the right side gear 53 so as to be movable in the axial direction.

The right side gear 53 includes clutch teeth 73 on the side facing the clutch member 71. The clutch member 71 includes corresponding clutch teeth 75 so as to face the clutch member 71. That is, the combination of the right side gear 53 and the clutch member 71 constitutes the clutch 7. When the clutch member 71 moves toward the right side gear 53 and the

clutch teeth

73 and 75 are connected to each other, the clutch 7 limits the differential between the

side gears

53 and 55. At this time, the differential device 1 is locked up.

The clutch member 71 includes a plurality of convex portions 77 on the side opposite to the clutch tooth 75 side. As shown in FIG. 3, the case body 21 includes a plurality of through holes 37 corresponding to the case main body 21, and the convex portions 77 pass through the through holes 37 and have their tips exposed to the outside.

Referring to FIG. 4 in combination with FIG. 3, the plunger 9 includes a plurality of claws 95 so as to correspond to the convex portions 77 and the through holes 37. As shown in FIG. 1, the claws 95 are arranged so as to abut on the convex portions 77 exposed to the outside through the through holes 37.

Referring back to FIGS. 1 and 2, the case main body 21 includes a wall portion 31 that extends in the radial direction with respect to its axis, and a trunnion 35 that extends from the wall portion 31 in the axial direction. The trunnion 35 includes a skirt portion 41, and the skirt portion 41 smoothly transitions the trunnion 35 to the wall portion 31, thereby reducing stress concentration therebetween. In the cross section, the outline of the skirt portion 41 can be a quarter circle as shown, or can be an elliptical arc or other similar shape. The smoother the stress concentration, the less the stress concentration. In the case of a quarter circle, the greater the radius R, the less the stress concentration.

The plunger 9 is slidably fitted on the outer periphery of the trunnion 35 and is movable in the axial direction. When the solenoid 13 drives the plunger 9 toward the clutch member 71, the claw 95 presses the convex portion 77, whereby the clutch 7 is connected. When the plunger 9 moves in the opposite direction, the clutch 7 is disconnected.

Referring mainly to FIGS. 5 and 6, the plunger 9 generally includes a first portion 93 and a second portion 91 fixedly fitted to the outer periphery thereof. Since the first portion 93 is the inner side in the present embodiment, this is referred to as an inner plunger and the second portion 91 is referred to as an outer plunger in the following description.

The outer plunger 91 is made of a magnetic material and has an annular shape around the axis. The outer plunger 91 faces the solenoid 13 and is disposed adjacent to it so as to efficiently receive the magnetic flux. The inner periphery is a cylindrical surface parallel to the axis, and is adapted to receive the inner plunger 93 inserted in the axial direction.

The end 91E on the side facing the wall portion 31 may be a plane orthogonal to the cylindrical surface, but the edge may be appropriately chamfered, or has a tapered shape that becomes narrower toward the end 91E. Also good. One or more protrusions 91P for contacting the wall portion 31 may protrude on the end 91E. These structures limit the contact area between the outer plunger 91 and the wall portion 31, thereby preventing the outer plunger 91 from adsorbing to the wall portion 31 due to residual magnetism.

The height of the protrusion 91 </ b> P only needs to be sufficient to prevent the end 91 </ b> E from coming into contact with the wall portion 31, and can be, for example, 0.1 mm or more. Further, in order to reduce the loss in the magnetic flux flowing from the end 91E to the wall portion 31, it is advantageous that the height of the protrusion 91P is low. For example, this can be reduced to 0.5 mm or less. The protrusion 91P can be rectangular, trapezoidal, triangular, or elliptical in its cross section.

The inner plunger 93 is made of a non-magnetic material such as stainless steel, aluminum alloy, or any engineering plastics, and generally has an annular shape around the shaft. The inner plunger 93 is press-fitted into the outer plunger 91 and is fixedly fitted. The outer periphery is a simple cylindrical surface that can be fitted with the outer plunger 91, but the inner periphery can have irregularities as appropriate. Such irregularities are advantageous in reducing friction against the trunnion 35 and holding the lubricating oil.

Except for the claw 95, the end 93E of the inner plunger 93 may also be a plane orthogonal to the cylindrical surface. The claw 95 projects outward in the radial direction, and extends in the axial direction from the claw 95 toward the clutch member 71. Corresponding to this, the outer plunger 91 includes a notch 91 </ b> N at an end facing the wall portion 31. The claw 95 protrudes outward in the radial direction through the notch 91N, and can be detoured so as not to collide with the skirt portion 41 of the trunnion 35. Such a structure contributes to increasing the degree of freedom in designing the skirt portion 41. Specifically, the skirt portion 41 can be enlarged or its R can be increased.

Further, the rear end surface 95E of the claw 95 can be brought into close contact with the notch 91N. Although the claw 95 bears the reaction force caused by driving the clutch member 71, this structure contributes to preventing the claw 95 from being deformed by the reaction force. Alternatively, the rear end face 95E may be separated without contacting the notch 91N. If they are not in contact, the outer plunger 91 does not directly bear the reaction force, so that the deformation of the outer plunger 91 can be prevented.

Referring mainly to FIG. 7, the end 91E of the outer plunger 91 protrudes toward the wall portion 31 from the end 93E of the inner plunger 93 except for the notch 91N. When the solenoid 13 drives the plunger 9 toward the clutch member 71 to connect the clutch 7, the end 91 </ b> E comes into contact with the wall portion 31 in advance. At this time, the inner plunger 93 is dimensioned so as not to come into contact with the wall portion 31 and the skirt portion 41.

Such a structure also contributes to increasing the degree of freedom in designing the skirt portion 41. Specifically, the skirt portion 41 can be enlarged or its R can be increased. Further, unlike the prior art, since it is not necessary to process the outer plunger 91 and the inner plunger 93 so that the end faces thereof are aligned, the manufacture thereof is remarkably easy.

As already described, the end 91E can be provided with one or more protrusions 91P. In this case, the protrusion 91P contacts the wall 31 instead of the surface of the end 91E. An air gap is maintained between the end 91E and the wall portion 31, and the air gap prevents the plunger 9 from adsorbing to the wall portion 31 due to residual magnetic flux or the like. On the other hand, as already described, if the protrusion 91P is sufficiently low, for example, 0.5 mm or less, the air gap does not hinder the jumping of the magnetic flux therebetween, and is therefore advantageous for efficiently using the magnetic flux.

Note that, unlike the above, the wall 31 may be provided with a protrusion for holding the air gap instead of the end 91E. Unlike the case where the protrusion 91 is formed on the end 91E, the processing is not easy, but the same effect can be obtained.

The solenoid 13 is symmetrical with respect to the axis and is annular around the axis. The solenoid 13 is coaxial with the differential case 3 and the plunger 9, and the solenoid 13 is fitted on the outer periphery of the plunger 9.

The solenoid 13 has an electromagnetic coil 15 for generating a magnetic flux and a core 17 for guiding the magnetic flux. The core 17 is prevented from rotating with respect to a carrier (stationary member) that houses the differential device 1. That is, the differential case 3 and the plunger 9 rotate relative to the solenoid 13 that is prevented from rotating. The wall portion 31 of the differential case 3 includes a groove 33 that runs in the circumferential direction, and the core 17 may be slidably fitted thereto.

The core 17 and the wall portion 31 of the differential case 3 constitute a magnetic circuit that surrounds the electromagnetic coil 15 leaving the gap 19. The wall 31 may include a portion 39 protruding toward the core 17, and the gap 19 may be held between the portion 39 and the core 17. The outer plunger 91 is disposed so as to straddle the gap 19. The magnetic flux generated by the electromagnetic coil 15 bypasses the gap 19 and flows around the outer plunger 91, and the magnetic flux drives the outer plunger 91 in the direction along the axis. The core 17, the wall portion 31, and the outer plunger 91 constitute a magnetic circuit that forms a closed loop M around the electromagnetic coil 15, which is advantageous for efficiently using the generated magnetic flux.

As in this embodiment, according to the structure in which the wall portion of the differential case is used as a part of the magnetic circuit and the magnetic material is brought into contact with the wall portion, the magnetic material tends to remain adsorbed on the wall portion due to residual magnetism. This is disadvantageous from the viewpoint of operating the actuator as intended by the driver, that is, it is contrary to the common sense of those skilled in the art to adopt such a structure. According to the present embodiment, by adopting such a structure, the inner plunger is separated from the wall portion, thereby increasing the degree of design freedom with respect to the shape of the skirt portion of the trunnion.

As already mentioned, the shape of the skirt is far more dominant in the strength of the differential case than the thickness of the trunnion or wall. In particular, rounding the skirt portion to give a relatively large R significantly improves the strength of the differential case. Since this embodiment provides a sufficient degree of design freedom for adopting such a design, it can contribute to improving the strength of the differential case.

Further, as in the prior art, if it is attempted to align the ends of the inner plunger and the outer plunger, difficulties are encountered in processing technology, but according to the present embodiment, such difficult processing is not necessary. It is only necessary to press-fit the inner plunger into the outer plunger and abut the rear end face of the claw against the notch of the outer plunger. Further, the nail and the notch can be easily formed by machining. That is, the present embodiment is advantageous over the prior art in terms of ease of processing.

Although the present invention has been described with reference to preferred embodiments, the present invention is not limited to the above embodiments. Based on the above disclosure, a person having ordinary skill in the art can implement the present invention by modifying or modifying the embodiment.

A differential device with a solenoid actuator that can improve the strength of the differential case is provided.

Claims

A differential case that is rotatable about an axis and includes a wall portion extending in a radial direction with respect to the axis; and a trunnion extending in the axial direction from the wall portion;
A differential gear set that is housed in the differential case and rotates together;
A clutch combined with the differential gear set;
A plunger that is slidably fitted to the trunnion and is movable in the axial direction from a first position allowing the clutch to be disengaged to a second position for engaging the clutch;
A first portion made of a non-magnetic material, slidably fitted around the trunnion, provided with a claw for pressing the clutch, and dimensioned so as not to contact the wall portion in the second position When,
A plunger comprising a second portion made of a magnetic material and fixedly fitted to the outer periphery of the first portion and dimensioned to abut against the wall at the second position;
A solenoid that slidably fits on the outer periphery of the second part and generates a magnetic flux that moves the second part in the axial direction;
A differential device with
2. The differential device according to claim 1, wherein the second portion includes a notch at an end facing the differential case, and the claw projects radially outward through the notch to skirt the trunnion. A differential device that is bypassing.
3. The differential apparatus according to claim 2, wherein the end of the second part protrudes in an axial direction from the first part toward the wall part except for the notch.
2. The differential apparatus according to claim 1, wherein the end of the second part includes a protrusion that limits a contact area between the second part and the wall part.