WO2016056114A1

WO2016056114A1 - Differential device

Info

Publication number: WO2016056114A1
Application number: PCT/JP2014/077149
Authority: WO
Inventors: 功廣田; 雅彦朝日
Original assignee: Ｇｋｎドライブラインジャパン株式会社
Priority date: 2014-10-10
Filing date: 2014-10-10
Publication date: 2016-04-14
Also published as: JP6306728B2; JPWO2016056114A1

Abstract

A differential device for distributing torque to a pair of axles extending along an axis comprises: a ring frame (10) surrounding the shaft, the ring frame (10) receiving the torque and being provided with a plurality of recesses (15) open radially inward toward the axis; a pair of side gears (40) each rotatable about the axis, the pair of side gears (40) being provided with a structure in which the pair of side gears (40) joined to the axles in a driving manner; a plurality of pinion gears (50) each comprising a shaft (53) and a head, the head having a gear section (51), the plurality of pinion gears (50) being configured such that, in order that the pinion gears (50) may receive the torque from the ring frame (10) and transmit the torque to the pair of side gears (40), the gear sections (51) respectively mesh with the pair of side gears (40) while the shafts (53) are rotatably fitted in the recesses (15) and the heads are directed radially inward; and a pair of side covers (20) joined to the ring frame (10) and covering the pair of side gears (40) and the plurality of pinion gears (50) in order to prevent the pair of side gears (40) and the plurality of pinion gears (50) from coming out.

Description

Differential equipment

The present invention relates to a differential apparatus for distributing torque from a driving force source to a pair of axles in an automobile.

For example, when a steered car travels, there must be a difference in rotational speed between the left and right wheels. That is, the automobile needs to transmit torque to both axles while allowing a differential between the pair of axles. For this purpose, a differential apparatus has been conventionally used.

There are historically established forms of differential devices for axles. That is, the differential device usually includes a cylindrical casing extending in the axial direction, the casing receives torque from the ring gear, and the differential gear set housed in the casing differentially transmits this torque to each axle. Distribute. As the differential gear set, a bevel gear type, a face gear type, a planetary gear type, or the like is practically used.

Patent Documents 1 and 2 disclose related technologies. Patent Document 1 relates to a bevel gear type and Patent Document 2 relates to a face gear type.

Japanese published patent publication 2013-100072 International Publication WO2005 / 040642A1

The gears that make up the differential gear set must withstand a large torque, and therefore require a certain size. Since the casing accommodates all such differential gear sets, the entire differential device tends to be large. The casing needs to firmly support the differential gear set, and the torque input to the casing generates a stress in the direction of twisting the casing. Therefore, the casing must have a sufficient thickness to have sufficient strength. Because of these factors, conventional differential devices have to be large and heavy. In particular, since the casing located on the outer periphery is thick and heavy, the moment of inertia significantly increases, which is a factor that impairs the vehicle response and fuel consumption.

The object of the present invention is to review the differential device from its basic structure and solve the above-mentioned problems.

According to one aspect of the present invention, a differential device that distributes torque to a pair of axles that extend in the direction of the shaft includes a plurality of recesses that surround the shaft and that open radially inward with respect to the shaft. A ring frame that receives the torque, a pair of side gears each having a structure that is rotatable about the shaft and is drivingly coupled to the axle, and a head and a shaft having a gear portion, respectively. A plurality of pinion gears, wherein the shaft is rotatably fitted in the recess to receive the torque from the ring frame and transmit the torque to the pair of side gears. A plurality of pinion gears that are inwardly engaged with both of the pair of side gears and the pair of side gears to be coupled to the ring frame and to prevent falling off. Comprising a pair of side covers covering the fine said plurality of pinion gears, a.

FIG. 1 is a perspective view of a differential apparatus according to an embodiment of the present invention, excluding a ring gear. FIG. 2 is an exploded perspective view in which only the jacket and the ring frame that support the pinion gear are extracted from the differential device. FIG. 3 is a sectional elevation view of the differential device, taken from a plane corresponding to the line III-III in FIG. FIG. 4 is a partial cross-sectional side view showing a combination of a cross-section of the pinion gear and the jacket and a side surface of the ring frame. FIG. 5A is a partial cross-sectional elevation view of the differential apparatus according to an example in which a ring gear is coupled to a ring frame. FIG. 5B is a partial cross-sectional elevation view of the differential device according to an example in which a ring gear is coupled to a side cover. FIG. 5C is a partial cross-sectional elevation view of the differential device according to an example in which one side cover is integrated with the ring gear.

Several exemplary embodiments of the present invention are described below with reference to FIGS. 1-5C.

Throughout the description and the appended claims, unless otherwise specified, the axis refers to the rotational axis of the differential device, and the circumferential and radial directions relate to such axis. Such an axis usually coincides with the rotational axis of the axle. Furthermore, the term ring does not exceed the meaning recognized in common sense, and thus does not include shapes such as cylinders having a substantial axial length with respect to diameter.

The differential device according to the present embodiment can be used, for example, in an automobile for distributing torque generated by a driving force source to left and right axles, or of course for a center differential apparatus in a four-wheel drive vehicle and other applications. Needless to say, it can also be used as part of a limited slip differential device, a lock-up differential device, or a free running differential device.

Referring mainly to FIG. 1 and FIG. 3, the differential apparatus according to the present embodiment generally includes a cage including a ring frame 10 and a pair of side covers 20, and a differential gear set housed in the cage. The whole is rotatably supported about the axis X by a carrier. The differential gear set includes a pair of side gears 40 and a plurality of pinion gears 50. According to the face gear type example in the figure, the side gear 40 is a disc-shaped crown gear, and the pinion gear 50 is a cylindrical gear. These teeth may be parallel to the shaft of the pinion gear 50, or a helical gear that is not parallel to the shaft may be used. The face gear type is advantageous in that the dimension in the axial direction is reduced, and there is an advantage that no thrust reaction force is generated in each pinion gear. Alternatively, a bevel gear type may be used instead.

The ring frame 10 is a member that receives torque from the driving force source and transmits the torque to the plurality of pinion gears 50. Although omitted in FIGS. 1-4, a ring gear for receiving torque is coupled to any of the cages. The ring gear will be described in detail later.

2 and 4 in combination with FIGS. 1 and 3, the ring frame 10 has a ring shape surrounding the axis X, and each includes a plurality of base portions 11 for supporting the pinion gear 50, and the base portions 11. And a plurality of bridge portions 13 that are coupled to each other. The ring frame 10 can be integrally formed by casting, mold pressing, forging, or other appropriate manufacturing method. Depending on the strength considerations associated with the manufacturing method, reinforcing or stiffening structures such as ribs not shown in the figures can be added to this.

Needless to say, the number of the base portions 11 normally matches the number of the pinion gears 50 and is 4 in the illustrated example, but is not limited thereto. The larger these numbers, the smaller the force that each element must bear, and therefore each element can be made smaller. This is advantageous for downsizing the differential device. On the other hand, the smaller the number, the smaller the number of parts, which is advantageous in terms of cost. They are preferably arranged symmetrically about the axis X and equally spaced in the circumferential direction.

Each base portion 11 has a recess 15 formed in a substantially central recess in the radial direction, that is, each base portion 11 defines a recess 15. Each recess 15 can have a cylindrical shape surrounded by a cylindrical surface, or a conical shape or a truncated conical shape surrounded by a conical surface. In this case, it can be directly fitted to and supported by the shaft 53 of the pinion gear 50. Alternatively, as shown in the figure, a rectangular or trapezoidal shape surrounded by the bottom wall 17 and the pair of peripheral walls 18 can be used, or another shape can be adopted. In such a case, the pinion gear 50 can be supported using a jacket 30 described later.

The pair of peripheral walls 18 can each be a plane orthogonal to the circumferential direction. According to this, since the applied torque does not generate a component force deviating from the circumferential direction, it is advantageous in terms of correct torque transmission. Or you may incline the surrounding wall 18 with respect to an orthogonal surface so that a component force may be generated dare. Further alternatively, the pair of peripheral walls 18 may be parallel to each other.

Each recess 15 opens at least inward in the radial direction, and preferably each recess 15 opens in both directions in the axial direction, and more preferably the pinion gear 50 (and / or a jacket 30 described later) is the shaft. Dimensioned to pass in the direction. If the pinion gear 50 is opened in the axial direction, the pinion gear 50 can be slid in the axial direction instead of the radial direction and can be assembled in the recess 15, which is advantageous in terms of ease of assembly.

For the convenience of supporting the pinion gear 50, the jacket 30 may be used. The jacket 30 is interposed between the shaft 53 of the pinion gear 50 and the recess 15. As best shown in FIG. 2, the jacket 30 has an outer shape corresponding to the recess 15, for example, a substantially rectangular parallelepiped or a trapezoid, and can be fitted into the recess 15. The pair of peripheral walls 32 corresponding to the peripheral wall 18 of the recess 15 may be any of a plane orthogonal to the circumferential direction, a plane inclined with respect to the orthogonal plane, and a plane parallel to each other. The jacket 30 includes a race 31 that opens inward in the radial direction, and a shaft 53 of the pinion gear 50 is fitted therein.

The jacket 30 is fitted into the recess 15 together with the pinion gear 50, is seated on the bottom wall 17, and is restrained in the circumferential direction by the pair of peripheral walls 18. The jacket 30 fitted in the recess 15 supports the shaft 53 in the radial direction so as to be rotatable. The ring frame 10 transmits torque to the pinion gear 50 via the peripheral wall 18 that is in contact with the jacket 30 exclusively.

Each bridge portion 13 integrally couples a pair of adjacent base portions 11 so that the entire ring frame 10 has a continuous structure in the circumferential direction. Each bridge portion 13 may be narrower in the axial direction than the plurality of base portions 11, and the thinned portions 14 may be formed on both sides thereof. Alternatively, or in addition to this, each bridge portion 13 may be thinner in the radial direction, and the thinned portion 16 may be formed on the outer periphery thereof. Furthermore or alternatively, in addition to or in addition, the inner periphery may also be formed with a lightening portion. These help reduce the weight and moment of inertia of the ring frame 10. Further, a gap is held between the bridge portion 13 and the side cover 20 by the lightening

portions

14 and 16 and is exposed to the outer periphery in the radial direction, but this gap allows passage of the lubricating oil and contributes to its circulation. .

Preferably, the center surfaces of the base portion 11 and the bridge portion 13 (that is, the ring frame 10) are aligned with the axial center of the shaft 53 in the axial direction. That is, the central plane and the central axis are arranged on a single plane orthogonal to the axis X. In this way, the torque received by the ring frame 10 is transmitted only to such a surface, and no force acts in the direction of twisting the ring frame 10, so that the ring frame 10 can be made thinner. That is, this also helps to reduce the weight and moment of inertia of the ring frame 10.

Each pinion gear 50 includes a gear portion 51 on its head and a shaft 53 on its leg, as best shown in FIGS. The top portion 55 may slightly protrude from the gear portion 51. The gear part 51, the shaft 53, and the top part 55 can be made into a single body. As already described, when the shaft 53 is inserted into the jacket 30 and is rotatably supported, and when the shaft 53 is inserted into the recess 15 together with the jacket 30, the shaft 53 is directed in the radial direction and the gear portion (head) 51 is moved in the radial direction. Directed inward.

Each side gear 40 is integrally provided with a gear portion 41 that expands in a radial shape in a flange shape and a cylindrical boss portion 43 that surrounds the axis X. One side gear 40 meshes with the plurality of pinion gears 50 from one side in the axial direction, and the other side gear 40 meshes from the other side. Further, each side gear 40 has a structure that is coupled to an axle, which is, for example, a spline 45 formed on the inner surface of the boss 43. The boss 43 is extended inward in the axial direction so as to sufficiently overlap the top 55 of the pinion gear 50. Since the spline 45 can be engaged with the axle with a sufficient length, the boss portion 43 does not need to be extended outward in the axial direction. This is advantageous in limiting the overall axial dimension of the differential gear set.

The pair of side covers 20 are dimensioned to cover the pair of side gears 40 and the plurality of pinion gears 50, and each include a cylindrical portion 21 that extends in the axial direction from each end thereof. The cylinder part 21 is a structure for fitting to the bearing of a carrier and being rotatably supported. Further, the side cover 20 can be so-called hollowed out, and is, for example, a plurality of through holes 27 that penetrate the side cover 20. The through hole 27 also contributes to the circulation of the lubricating oil.

The ring frame 10 has a plurality of bolt holes 19, and each side cover 20 also has a plurality of bolt holes 23 corresponding thereto, and the pair of side covers 20 is attached to the ring frame by bolts 25 passed through them. 10 is fixed. The pair of side gears 40 and the plurality of pinion gears 50 are exclusively covered with the pair of side covers 20, and thus are prevented from falling off.

Each pinion gear 50 can move in both directions in the axial direction as long as each jacket 30 is limited to the side cover 20. In order to allow such movement, the jacket 30 is slightly shorter than the axial length of the recess 15, and therefore, play is secured in the axial direction between the jacket 30 and the side cover 20 in the recess 15. The

Since each pinion gear 50 is allowed to move in the axial direction, the meshing between each pinion gear 50 and the side gear 40 is automatically aligned. This eliminates the need for precise positional adjustment of each pinion gear 50 or each side gear 40, and helps to improve the durability and quietness of each gear.

Each pinion gear 50 is held in place in the axial direction exclusively by meshing with the side gear 40. In the radial direction, each pinion gear 50 is restricted from moving outward by being seated on each jacket 30 or each bottom wall 17 of the ring frame 10, but there is no special means for restricting it inward. Each pinion gear 50 is held at a fixed position by the top 55 being in contact with the boss 43 of the side gear 40. That is, this embodiment does not require any means other than the side gear 40 in order to hold the pinion gear 50 in a fixed position.

The leg portion of each pinion gear 50 is restrained to some extent by each jacket 30, but the head portion does not have to be restrained by any member. The shaft 53 is supported by the jacket 30 on the radially outer side, but does not need to be supported by any member at the radially inner end. Needless to say, each shaft 53 is not fixed to the ring frame 10 by pin coupling or the like.

With the combination as described above, the torque input to the ring frame 10 is transmitted to the plurality of pinion gears 50 fitted in the recesses 15, further transmitted to the pair of side gears 40 engaged with the pinion gears 50, and distributed to both axles. The Since the pinion gear 50 and the side gear 40 constitute a differential gear set, a differential is allowed between the two axles.

In order to input torque to the ring frame 10, the ring gear 60 is coupled to one of the cages, but there are various variations in the relationship between the two as shown in FIGS. 5A to 5C. In any case, the coupling can be performed by welding, for example, or the object to be coupled and the ring gear 60 may be integrally formed. Alternatively, mechanical coupling such as spline coupling or bolt coupling may be used. Each figure shows an example in which the ring gear 60 is a spur gear or a helical gear, but a hypoid gear or another type of gear may be used instead.

Referring to FIG. 5A, the ring gear 60 may be coupled to the ring frame 10. In this case, particularly when the ring gear 60 is a spur gear, the rotation surface F of the ring gear 60 may be aligned with the center surface of the ring frame 10 and the axial center of the shaft 53. Since no offset occurs between the input and output of the torque T, it is not necessary to consider the stress in the torsional direction, and all related parts can be designed smaller and thinner.

In this example, the differential device can be symmetric. The right part and the corresponding left part may be compatible with each other, which is advantageous in terms of production cost.

Alternatively, particularly when the ring gear 60 is a helical gear or a hypoid gear, an appropriate offset is provided in the ring gear 60 according to the thrust force or other force generated in the ring gear 60, or any member is reinforced or A structure such as a rib for stiffening may be added.

Further, in the example of FIG. 5A, since no torque is applied to the side cover 20, the side cover 20 can also be designed to be thin. These help reduce the weight and moment of inertia of the differential device.

Alternatively, referring to FIG. 5B, the ring gear 60 may be coupled to one side cover 20. In this example, an offset S occurs between the rotation surface F of the ring gear 60 and the center C of the shaft 53, which is much smaller than the offset in the prior art. Therefore, there is no need to take special measures against torsional stress, which helps to reduce the weight and moment of inertia of the differential device.

Further or referring to FIG. 5C, the ring frame 10 may be integrated with one of the pair of side covers 20, and the ring gear 60 may be coupled thereto. Alternatively, the ring gear 60 may be coupled to the other side cover 20 that is not integral with the ring frame 10. In any case, the ring gear 60 may have an offset with respect to the center of the shaft 53, but may not have an offset as shown in the figure.

In any of the above-described embodiments, the assembly of the differential device is remarkably easy. For example, in assembling, one side of the pair of side covers 20 is placed on a work table with one side laid down, one of the pair of side gears 40 is placed together with a washer, the ring frame 10 is then placed thereon, and each jacket is then placed. By inserting the pinion gear 50 inserted into 30 into the recess 15, then placing the remaining side gear 40 together with the washer, then covering the remaining side cover 20 on it, and finally fastening them with bolts . At any stage, the target location of the part to be assembled is open upward, and the assembly is remarkably easy.

In the prior art, for example, when a pinion gear is incorporated, it is necessary to insert the shaft from the outside while aligning the shaft hole with the hole of the casing while incorporating the pinion gear deep inside the narrow casing. Such a difficult process does not exist in this embodiment.

Any of the embodiments has the following effects. Since the ring frame having a small dimension in the axial direction supports the pinion gear without using the casing extending in a cylindrical shape in the axial direction, the entire differential device can be made small. If the differential device is small, it is possible to reduce the size of the carrier that supports the differential device and the structure on the vehicle body side such as a transmission or transfer combined therewith.

Furthermore, the space in the vehicle that has been allocated to the differential device and the carrier in the prior art can be allocated to other uses. In other words, the vehicle body design provides a great degree of freedom.

There is little or no stress in the direction of twisting the ring frame, so it can be made thin and small, and it can be subjected to a lot of lightening, thus reducing its weight and moment of inertia. Can be reduced. Furthermore, since little or no stress based on the torque to be transmitted is applied to the pair of side covers, they can also be made thin and small, thus reducing their weight and moment of inertia. Further, as apparent from the above, the total weight including not only the differential device but also the carrier is reduced. This also contributes to reducing the total weight of the car body. These contribute to improving the response and fuel consumption of automobiles.

Also, the cage can have many through holes and gaps that penetrate therethrough, and the lubricating oil can smoothly circulate in and out of the differential device through these. That is, this embodiment is also advantageous in terms of lubrication.

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 small, light and small moment of inertia differential device is provided.

Claims

A differential device that distributes torque to a pair of axles extending in a shaft direction,
A ring frame that surrounds the shaft and includes a plurality of recesses that are radially inwardly open with respect to the shaft and receive the torque;
A pair of side gears each capable of rotating about the shaft and having a structure for drivingly coupling to the axle;
A plurality of pinion gears each having a head portion having a gear portion and a shaft, wherein the shaft is rotatable in the recess so as to receive the torque from the ring frame and transmit the torque to the pair of side gears. A plurality of pinion gears that are fitted and faced inward in the radial direction, and the gear portion meshes with both of the pair of side gears;
A pair of side covers that are coupled to the ring frame and cover the pair of side gears and the plurality of pinion gears to prevent falling off;
A differential device with
The differential device according to claim 1, wherein the head portion of the pinion gear is not restrained by a member other than the side gear.
2. The differential device according to claim 1, wherein each of the shafts is restricted to move outwardly in a circumferential direction and a radial direction with respect to the shaft by the recess, and can move in both directions in the direction of the shaft. , Differential equipment.
4. The differential device according to claim 3, wherein the recess is also opened in the direction of the shaft so as to allow the shaft to pass in the direction of the shaft.
The differential device according to claim 3, comprising:
Each further comprising a jacket interposed between the shaft and the recess and rotatably supporting the shaft in the radial direction;
The differential device, wherein the recess is dimensioned to abut against the jacket in the circumferential direction and not abut against the jacket in the axial direction.
6. The differential device of claim 5, wherein the jacket is dimensioned to have play in the axial direction between the jacket and the side cover in the recess.
7. The differential device according to claim 1, wherein the ring frame includes a plurality of base portions that define the recess and abut against the pair of side covers, and the plurality of base portions. And a plurality of bridge portions that are coupled and narrower in the axial direction than the base portion or thinner in the radial direction.
The differential apparatus according to claim 1, wherein the ring frame is integral with any one selected from the pair of side covers.
The differential device of claim 1, comprising:
A differential device further comprising a ring gear integral with the ring frame.
2. The differential apparatus according to claim 1, wherein the ring frame is symmetrical with respect to the center plane in the axial direction.
2. The differential apparatus according to claim 1, wherein the pair of side covers are symmetrical with respect to the center plane of the ring frame in the axial direction.