JP2011099479A - Differential gear unit - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a low-cost differential gear unit of simple structure capable of reducing the viscosity of lubricating oil early by quickening the temperature rising speed of the lubricating oil at a low temperature. <P>SOLUTION: This differential gear unit includes: a housing 11; side gears 21 and 22 rotatably held inside of the housing 11; and pinion gears 23 and 24 rotatably held inside of the housing 11, and interposed between the side gears 21 and 22. The housing 11 includes: one or more recessed holding parts 33 and 34 for rotatably holding the pinion gears 23 and 24; and friction members 36 and 37 arranged between both the recessed holding parts 33, 34 and the pinion gears 23, 24 and formed from a raw material having a coefficient of linear expansion larger than that of the pinion gears 23 and 24 and formed into a nearly semi-cylindrical shape along the outer peripheral surfaces of the pinion gears 23 and 24. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a differential gear device, and more particularly to a differential gear device suitable for a torque-sensitive limited slip differential device for a vehicle.

  In general, a differential gear device mounted on a vehicle, for example, a rear differential device or a front differential device that allows differential movement of left and right wheel drive shafts, includes a housing (differential case) in which a ring gear is sheathed, and left and right wheel drive shafts. Left and right side gears (differential side gears) that are rotatably accommodated in the housing in a state where they can be coupled to each other, and at least one pinion gear (differential pinion gears) that is rotatably supported by the housing so as to mesh with both side gears. The rotary power input from the ring gear to the housing is distributed to the left and right wheel drive shafts, and the rotational speed difference between the left and right wheel drive shafts can be allowed when the vehicle turns. . Also, a differential gear device such as a so-called center differential is used between front and rear propulsion shafts or between a wheel drive shaft and a propulsion shaft (hereinafter referred to as a drive shaft in the sense of a wheel drive shaft or propulsion shaft). Torque is distributed to both drive shafts while absorbing these rotational speed differences.

  In addition, the differential tolerance range allows the torque difference between the drive shafts so that the driving force can be reliably transmitted to the left and right (or front and rear) drive shafts on slippery road surfaces and the slipping of the removed drive wheels can be prevented. In many cases, a differential limiting type device, which is appropriately limited in accordance with a rotation difference (rotational speed difference) or the like, that is, a limited slip differential device.

  In this type of conventional differential gear device, left and right side gears and a plurality of parallel pinion gears that mesh with both side gears in part in the axial direction and mesh with each other in the remaining part in the axial direction can be rotated inside the housing. The two side gears are rubbed against the thrust washer on the housing side using the thrust force (axial thrust) generated during torque transmission of multiple side gears consisting of helical gears, etc. There is known one in which the differential is limited by rubbing the outer peripheral portions of a plurality of rotating pinion gears with a housing or a member on the housing side (see, for example, Patent Document 1).

  In addition, the pinion gear and the side gear that slide and rotate while receiving torque are flexible between the pinion gear and the side gear and the housing in order to eliminate heat treatment that increases the wear resistance of the housing and causes deformation and high costs. There is known one in which a wear-resistant sleeve is press-fitted (see, for example, Patent Document 2).

  Further, a plurality of divided cylindrical clamping members that surround the pinion gear from the outside are coupled by a tension spring to urge the plurality of pinion gears to the side gear side (for example, see Patent Documents 1 to 3), or both ends of the housing Pinion gear sets adjacent to a pair of recesses on the inner surface side of each toggle member that engages a plurality of toggle members so as to be swingable in the respective recesses on the outer surface side with respect to a plurality of support columns connecting the plates (A pair of pinion gears meshing with each other) is held, and the plurality of toggle members are biased toward the plurality of pinion gear sets by the cam surfaces of the outer peripheral portions of the plurality of toggle members and the ring members and spring members engaged therewith. There is one that biases the pinion gear set toward the side gear (see, for example, Patent Document 4).

  In addition, a housing in which a planetary gear type differential gear is housed in a housing is also known. In this differential gear device, a first output member that can be coupled to one drive shaft is spline coupled to an internal ring gear that is rotatably housed in the housing, and can be coupled to the other drive shaft. Is configured as a sun gear and is rotatably held in a carrier fixed to the housing. The pinion gear held rotatably on the carrier meshes with the internal ring gear and the sun gear. The differential limitation which responds to the torque difference of the drive shaft can be executed (see, for example, Patent Document 5).

JP 7-332466 A Japanese Patent Laid-Open No. 7-127712 JP 2000-120840 A JP 9-42420 A Japanese Patent No. 3944401

  However, in the conventional differential gear device as described above, the friction between the outer peripheral portion of the pinion gear that is amplified and rotated at the time of differential and the housing or the member on the housing side is effective for generating the differential limiting torque. For this reason, a very small sliding clearance has been set between the outer periphery of the pinion gear and the housing. For this reason, if it takes time from the start of running of the vehicle until the temperature of the lubricating oil in the housing rises, the viscosity (dynamic viscosity) of the lubricating oil in the housing continues to be high. A large differential resistance works, and there is a problem that the fuel consumption is reduced particularly when driving in a low temperature environment. In the low temperature environment, the temperature of the lubricating oil in the housing decreases to, for example, an environmental temperature below freezing point, and the kinematic viscosity of the lubricating oil in the housing remains very high for a while from the start of traveling.

  On the other hand, in the case of a mechanism having a mechanism that biases the pinion gear toward the side gear, the sliding clearance between the pinion and the member on the housing side is not fixed, but there is a problem that the biasing mechanism is complicated. In addition to this, there is a problem that fuel efficiency is lowered due to a relatively large differential resistance acting when the vehicle turns.

  In addition, in a case where a flexible wear-resistant sleeve is press-fitted into the housing, not only is the moldability of the sleeve poor, but it becomes a flexible large part, and the handling is troublesome, so the workability is low. Unfortunately, there was a problem that the cost of the differential gear device was eventually increased.

  The present invention has been made in order to solve the above-described conventional problems, and can reduce the viscosity of the lubricating oil early by increasing the temperature rising rate of the lubricating oil at a low temperature with a simple configuration. An object of the present invention is to provide a differential gear device.

  In order to achieve the above object, the differential gear device according to the present invention includes (1) a housing, one side rotatably held so as to be positioned on one side and the other side in the rotation center axis direction inside the housing, and A differential gear device comprising: an output gear on the other side; and at least one small gear rotatably held inside the housing so as to be interposed between the output gears on the one side and the other side. The housing is provided with at least one concave holding portion for rotatably holding the small gear, and is made of a material having a larger linear expansion coefficient than the small gear between the concave holding portion and the small gear. Further, at least one friction member formed in a divided cylindrical shape along the outer peripheral surface of the small gear is provided.

  With this configuration, the split cylindrical friction member along the outer peripheral surface of the small gear tends to reduce the radius of curvature at low temperatures, thereby increasing the friction contact area and friction force between the outer peripheral portion of the small gear and the friction member. However, when the friction member has a high temperature, the radius of curvature tends to be increased, so that the friction contact area and friction force between the outer peripheral portion of the small gear and the friction member are reduced. Therefore, when power transmission is started when the temperature of the lubricating oil in the housing is low and the viscosity is high, the small gear and the friction member rub against each other strongly to generate heat, and lubricate to a temperature at which the viscosity of the lubricating oil sufficiently decreases. The oil will heat up early. The inner surfaces of the friction member and the recessed holding portion of the housing are preferably substantially semi-cylindrical. The friction member may be made of a material having a larger linear expansion coefficient than the housing.

  In the differential gear device having the configuration described in (1) above, (2) the friction member reduces the radius of curvature at a low temperature with respect to the outer peripheral surface of the small gear, while increasing the radius of curvature at a high temperature. It is preferable that they are arranged as described above.

  With this configuration, the contact area between the small gear and the friction member at a low temperature and at a high temperature can be greatly changed, and a sufficient amount of heat can be ensured due to friction between both at a low temperature. In this case, the gap between the housing and the small gear may be slightly larger at both ends of the friction member in the circumferential direction than at the center in the same direction, and the radius of curvature of the inner surface of the concave holding portion of the housing However, it may have a value closer to that at the high temperature than the radius of curvature at the low temperature of the outer peripheral surface of the friction member (smaller than the radius of curvature of the outer peripheral surface at the high temperature but larger than that at the low temperature).

  In the differential gear device having the configuration described in the above (1) and (2), (3) the friction member is at least a central portion in the circumferential direction of curvature between the concave holding portion and the small gear. It is preferable to insert with a preset interference.

  With this configuration, a sufficient amount of heat generated by friction between the small gear and the friction member at a low temperature can be secured. Note that by increasing the plate thickness of the friction member to some extent, it is possible to sufficiently secure the tendency to reduce the radius of curvature at low temperatures and the tendency to increase the radius of curvature at high temperatures. In addition, since the small gear rotates while being lubricated with the lubricating oil with respect to the friction member, the friction member has a tightening allowance that is equivalent to or slightly larger than the change in the thickness of the friction member due to a change in operating temperature. The durability of can be secured.

  In the differential gear device having the configuration according to any one of (1) to (3), (4) the output gears on the one side and the other side are configured by a pair of external gears, and the at least 1 A pair of small gears rotatably held inside the housing so as to mesh with the output gears on the one side and the other side in a part in the axial direction, and meshed with each other in the remaining part in the axial direction. The at least one concave holding portion and the at least one friction member of the housing preferably include a pair of concave holding portions and a pair of friction members corresponding to the pair of small gears.

  With this configuration, at least the outer peripheral portions of the pair of small gears can be brought into frictional contact with the friction member, and the temperature increase rate of the lubricating oil at a low temperature can be increased.

  In the differential gear device described in (4) above, (5) the pair of friction members is configured as a combined friction member integrally coupled in the vicinity of the meshing portion of the small gear pair, and the combined friction member is It is preferable that the housing engages with the housing in the vicinity of the coupling portion of the pair of friction members, and the small gear pair engages with an inner surface portion of the pair of friction members.

  With this configuration, the number of parts for friction can be halved, and the frictional force between the friction member and each small gear can be accurately changed according to the temperature of the lubricating oil in the housing.

  In the differential gear device described in (4) and (5) above, (6) the pair of small gears are arranged around the output gear on the one side and the other side in parallel with the output gear. It is preferable that

  With this configuration, the housing hole and recess of the housing for housing the output gear and the small gear can be easily formed, and the attaching operation of the friction member is performed in the same direction as the direction in which the output gear and the small gear are inserted into the housing. Workability is good.

  In the differential gear device described in (4) and (5) above, (7) the pair of small gears rotate about an axis perpendicular to the output gear on the one side and the other side. Also good.

  With this configuration, even in a worm gear type torque-sensitive differential gear device, a friction member can be disposed between the worm gear type small gear and the housing.

  In the differential gear device according to any one of (1) to (3), (8) an internal ring gear in which the output gears on the one side and the other side are rotatably housed inside the housing; A sun gear rotatably accommodated in the housing, and the small gear is rotatably held by a carrier fixed to the housing, and the internal gear and the sun gear. It is comprised by the planetary pinion gear which meshes | engages in, and the said recessed holding part may be provided in the said carrier.

  With this configuration, even with a planetary gear mechanism type differential gear mechanism, a friction member can be disposed between the small gear serving as the planetary gear and the housing.

  The friction member is more preferably made of a material having a linear expansion coefficient that is about twice or more larger than that of the housing and the small gear. Further, it is preferable that the surface of the friction member is subjected to wear resistance treatment (surface coating, heat treatment for hardening the surface, etc.). The friction member may change its shape when it reaches a set temperature, such as a shape memory element alloy or bimetal, but the linear expansion coefficient is a small gear in terms of cost and durability. A bigger one is better. Needless to say, the output gear and the small gear on the one side and the other side are lubricated by the lubricating oil accommodated in the housing.

  According to the present invention, when the viscosity of the lubricating oil in the housing is low, the differential gear of the output gear is increased and the rotating small gear and the friction member are strongly rubbed to generate heat, and the viscosity of the lubricating oil is sufficiently lowered. Since the temperature of the lubricating oil is raised to an early temperature, the low-cost differential gear can reduce the viscosity of the lubricating oil early by increasing the temperature rising speed of the lubricating oil at a low temperature with a simple configuration. An apparatus can be provided.

It is principal part sectional drawing of the differential gear apparatus which concerns on 1st Embodiment of this invention. It is an expanded sectional view of a small gear pair and a friction member in a differential gear device concerning a 1st embodiment of the present invention. It is sectional drawing which shows the whole structure of the differential gear apparatus which concerns on 1st Embodiment of this invention. (A) is operation | movement explanatory drawing at the time of the power transmission in the differential gear apparatus which concerns on 1st Embodiment of this invention, (b) is operation | movement explanatory drawing at the time of the differential in the differential gear apparatus which concerns on 1st Embodiment. It is. (A) is a graph which shows the difference of the emitted-heat amount of the four Examples which made the friction member of the differential gear apparatus which concerns on 1st Embodiment different, and the comparative example, (b) is the differential gear. It is a graph which shows the relationship between the temperature of the lubricating oil in an apparatus, and the fuel consumption of a vehicle. It is sectional drawing which shows the whole structure of the worm gear type differential gear apparatus which concerns on 2nd Embodiment of this invention. It is sectional drawing which shows the whole structure of the differential gear apparatus of the planetary gear mechanism type | mold which concerns on 3rd Embodiment of this invention. It is arrangement | positioning explanatory drawing of the small gear pair of the differential gear apparatus which concerns on 4th Embodiment of this invention.

  Hereinafter, preferred embodiments of the present invention will be described with reference to the drawings.

(First embodiment)
1 to 4 show the configuration of the differential gear device according to the first embodiment of the present invention. This differential gear device constitutes a torque-sensitive limited slip differential device for vehicles. When rotational power is input from a final drive gear of a transmission (not shown), the differential gear device is applied to the left and right drive shafts. The rotational power is transmitted while allowing the differential between the two shafts.

  As shown in FIGS. 1 and 3, the differential gear device 10 of the present embodiment is rotatably supported by a transmission case (not shown) so as to rotate around a rotation center axis C, and the final drive of the transmission A housing 11 for inputting rotational power from the gear is provided.

  The housing 11 is a differential case in which an external ring gear 12 (see FIG. 3) that meshes with the final drive gear is fastened and fixed by a plurality of bolts 13, and has a substantially bottomed cylindrical case body 14. And the cover part 15 with which the opening end side was equipped is comprised. The case main body 14 and the cover 15 are fastened together with the ring gear 12 by a bolt 13.

  Inside the case main body portion 14 of the housing 11 are side gears 21 and 22 (output gears) on one side and the other side located on one side and the other side in the direction of the rotation center axis C (hereinafter simply referred to as the rotation center axis direction). ) Are rotatably housed and held, and a plurality of pairs of pinion gears 23 and 24 (small gears) are rotatably housed so as to be positioned around both side gears 21 and 22. The side gears 21 and 22 and the pinion gears 23 and 24 have meshing teeth 21t, 22t, 23t, and 24t that can mesh with each other.

  The side gears 21, 22 have spline teeth 21 a, 22 a that spline-couple inner ends of the left and right drive shafts D 1, D 2 (wheel drive shafts; see FIG. 4) on the inner peripheral side thereof. The shaft holes 11h and 11i with lubrication grooves into which the inner ends of the left and right drive shafts D1 and D2 are inserted are coaxially formed.

  The plurality of pairs of pinion gears 23, 24 are arranged around both side gears 21, 22 and parallel to both side gears 21, 22. The pinion gears 23 and 24 are rotatably held inside the case main body 14 so as to mesh with the side gears 21 and 22 at a part in the axial direction, for example, at an intermediate part in the axial direction. The other part, for example, both ends in the axial direction mesh with each other.

  Specifically, as shown in FIGS. 3 and 4, the plurality of pairs of pinion gears 23, 24 are similar to the short gear portions 23 a, 24 a located on one end side in the axial direction and the short gear portions 23 a, 24 a. A long gear portion 23b, 24b having a tooth shape and extending from the intermediate portion in the axial direction to the other end side, and a cylindrical intermediate portion having a smaller diameter connecting these short gear portions 23a, 24a and the long gear portions 23b, 24b. It is comprised by the connection parts 23c and 24c. The pair of pinion gears 23 and 24 (small gear pairs) are arranged in opposite directions so that the short gear portion 23a meshes with the long gear portion 24b and the short gear portion 24a meshes with the long gear portion 23b. ing. Each pinion gear 23 meshes with one side gear 21 at the inner end portion of the long gear portion 23b located at the axial intermediate portion, and each pinion gear 24 is a long gear portion 24b located at the axial intermediate portion. Is engaged with the side gear 22 on the other side. Here, each of the side gears 21 and 22 and the pinion gears 23 and 24 is constituted by a helical gear, for example, and is lubricated by the lubricating oil (lubricating oil) accommodated in the housing 11.

  On the other hand, as shown in FIGS. 1 and 2, the housing 11 has an annular annular holding portion 31 that holds the side gears 21 and 22 on one side and the other side so as to be slidably rotatable with a predetermined sliding clearance, 32 and a plurality of pairs of substantially semi-cylindrical (divided cylindrical) holding portions 33 and 34 for rotatably storing and holding a plurality of pairs of pinion gears 23 and 24, respectively. The portions 33 and 34 are arranged adjacent to each other so as to correspond to each pair of pinion gears 23 and 24 that mesh with each other.

  Further, between the pair of concave holding portions 33, 34 of the housing 11 and the corresponding pair of pinion gears 23, 24, they are close to the outer peripheral surfaces 23e, 24e (see FIG. 2) of the pinion gears 23, 24. Friction members 36 and 37 formed in a substantially semi-cylindrical shape (divided cylindrical shape) are provided along the corresponding outer peripheral surfaces 23e and 24e.

The friction members 36 and 37 are made of a material having a larger linear expansion coefficient than that of the side gears 21 and 22 and the pinion gears 23 and 24. Preferably, the linear expansion coefficient is about twice that of the materials of the gears 21, 22, 23 and 24. It is made of more material Specifically, the friction members 36 and 37 are made of, for example, aluminum having a linear expansion coefficient of about 23 × 10 ⁻⁶ / K, and the side gears 21 and 22 and the pinion gears 23 and 24 each have a linear expansion coefficient of about 11 × 10 6. It is made of ^-6 / K steel. In this embodiment, the housing 11 is also made of steel, and the friction members 36 and 37 are made of a material having a larger linear expansion coefficient than the housing 11 as well as the pinion gears 23 and 24.

  As described above, the substantially semi-cylindrical friction members 36 and 37 having a large linear expansion coefficient with respect to other members are indicated by a solid line in FIG. 2 at a low temperature when the temperature of the lubricating oil in the housing 11 is low. Further, the outer peripheral surfaces 23e and 24e of the pinion gears 23 and 24 contract with a tendency to reduce the radius of curvature r1, while heat generation continues for power transmission and differential of the differential gear device 10. When the temperature is high, as shown by phantom lines in FIG. 2, the diameters of the outer peripheral surfaces 23e and 24e of the pinion gears 23 and 24 are increased in a tendency to increase the curvature radius r1. For example, in the case of the differential gear device 10 mounted on a vehicle, the differential gear device 10 can be used in a low-temperature environment, for example, below the freezing point up to about −40 ° C., while the temperature of the lubricating oil in the housing 11 is 160 ° during continuous running, for example. Can rise to near C.

  By the way, the friction member 36 of the coupling friction member 35 inserted into the gap between the pinion gears 23 and 24 meshing with the side gears 21 and 22 and the substantially semi-cylindrical concave holding portions 33 and 34 of the housing 11, The thickness of 37 is set slightly larger. That is, a so-called tightening margin (a tightening margin in the revolving radial direction of the pinion gears 23 and 24 passing through the centers of the side gears 21 and 22 and the pinion gears 23 and 24) is set for the friction members 36 and 37. Is set to a value that is about the thickness change of the friction members 36 and 37 in the operating temperature range (for example, −40 ° C. to 160 ° C.) or slightly larger than that, for example, 0.04 mm.

  In addition, each pair of the friction members 36 and 37 among the plurality of pairs is in the vicinity of the meshing portion of each corresponding pair of pinion gears 23 and 24 (small gear pair), that is, the ends of the friction members 36 and 37 that are close in the circumferential direction of curvature. They are integrally coupled to each other on the part side to constitute a coupling friction member 35. The coupling friction member 35 is engaged with the housing 11 in the vicinity of the coupling portion between the pair of friction members 36 and 37 and restrained in position, and the inner surface forming the curvature surface of the curvature radius r1 of the pair of friction members 36 and 37. Is engaged with the pinion gears 23, 24.

  Further, the gap between the housing 11 and the pinion gears 23 and 24 is slightly larger at both arms of the coupling friction member 35 in the circumferential direction of the curvature of the friction members 36 and 37 than at the center in this direction. The inner radius of curvature r1 of the concave holding portions 33, 34 of the housing 11 is a value closer to that at the higher temperature than the radius of curvature of the outer circumferential surface of the friction members 36, 37 (from the radius of curvature of the outer circumferential surface at the higher temperature). Small but larger than that at low temperature).

  Next, the operation will be described.

  In the differential gear device 10 of the present embodiment configured as described above, rotational power is input from the final drive gear to the ring gear 12 during driving of the vehicle. At this time, the housing 11 is rotated by the reduced rotation of the ring gear 12, and the pinion gears 23, 24 rotate (revolve) around the side gears 21, 22 together with the housing 11, as shown in FIG. 22 rotates in the same direction, and rotational power in the traveling direction is transmitted to the left and right drive shafts D1, D2.

  Also, as shown in FIG. 4B, when a difference in rotation (angular velocity) occurs between the left and right drive shafts D1, D2 when the vehicle turns, etc., the differential coupling is achieved through a plurality of pairs of pinion gears 23, 24. The side gears 21 and 22 thus rotated relative to each other to allow differential rotation of the left and right drive shafts D1 and D2. At this time, the pinion gears 23 and 24 having a smaller number of teeth than the side gears 21 and 22 are in a rotating state in which the differential rotation of the side gears 21 and 22 is increased.

  On the other hand, at a low temperature when the environmental temperature of the vehicle is low and the temperature of the lubricant contained in the housing 11 is low when the vehicle starts to travel, a plurality of pairs of pinion gears 23, 24 are shown as shown by the solid line in FIG. The substantially semi-cylindrical friction members 36, 37 of the plurality of coupled friction members 35 along the outer peripheral surfaces 23e, 24e tend to reduce the respective curvature radii r1, so that the friction members 36 of the plurality of coupled friction members 35, The frictional contact area and the frictional force between the outer periphery of 37 and the plurality of pairs of pinion gears 23 and 24 increase. Therefore, when the vehicle starts running at this low temperature, the transmission torque from the final gear and the drive shaft to the meshing part of the ring gear 12, the bearing part of the housing 11, the meshing parts of the side gears 21, 22 and the pinion gears 23, 24, etc. Heat is generated according to the driving loads of D1 and D2, and heat is generated between the plurality of pairs of pinion gears 23 and 24 and the plurality of pairs of friction members 36 and 37. In particular, when a differential occurs in the drive shafts D1 and D2, more frictional heat is generated between the pinion gears 23 and 24 that are rotated at an increased speed and the friction members 36 and 37 that increase the friction toward the pinion gears 23 and 24 at a low temperature. Will occur.

  Therefore, within a short time after the start of traveling at a low temperature when the viscosity of the lubricating oil inside the housing 11 is high, the lubricating oil is quickly heated up to a temperature at which the viscosity of the lubricating oil sufficiently decreases. The conventional problem that the fuel efficiency is lowered due to the relatively large differential resistance acting by the high-viscosity lubricant during turning or the like is solved.

  Further, when the temperature of the lubricating oil inside the housing 11 is high and the viscosity of the lubricating oil is lowered, as shown by the phantom line in FIG. , 37 tend to increase the respective curvature radii r1, and the frictional contact area and frictional force between the friction members 36, 37 of each coupling friction member 35 and the outer periphery of each pair of pinion gears 23, 24 are reduced. become. Therefore, the temperature of the lubricating oil inside the housing 11 is prevented from excessively rising during continuous running.

  In the present embodiment, the friction members 36 and 37 are made of a material having a linear expansion coefficient larger than that of the pinion gears 23 and 24, and are substantially semi-cylindrical along the outer peripheral surfaces 23e and 24e of the pinion gears 23 and 24. Friction contact between the outer peripheral portions of the pinion gears 23 and 24 due to deformation of the friction members 36 and 37 with respect to the outer peripheral surfaces 23e and 24e of the pinion gears 23 and 24 at low temperatures without using a material or operation means. On the other hand, the area and the frictional force are increased, and at high temperatures, the outer peripheral surfaces 23e and 24e of the pinion gears 23 and 24 are deformed to expand and the frictional contact area and the frictional force between the outer peripheral portions of the pinion gears 23 and 24 are increased. It can be reduced and the cost is low. In addition, the sliding clearance of the pinion gears 23 and 24 that slide and rotate inside the housing 11 can be kept constant.

  In addition, in the present embodiment, each pair of friction members 36 and 37 is coupled at the ends in the circumferential direction of curvature to form the combined friction member 35, so that the number of parts for friction can be halved. In addition, the frictional contact area and the frictional force between the friction members 36 and 37 and the pinion gears 23 and 24 can be changed more accurately according to the temperature of the lubricating oil inside the housing 11.

  Further, the housing holes and recesses of the housing 11 for housing the side gears 21 and 22 and the pinion gears 23 and 24 can be easily formed, and the mounting work of the friction members 36 and 37 can be performed on the housing 11 of the side gears 21 and 22 and the pinion gears 23 and 24. It can be performed in the same direction as the direction of insertion inside, and the workability is good.

  Further, a tightening margin is set for the friction members 36 and 37 of the coupling friction member 35, and the set value of the tightening margin is about a change in the thickness of the friction members 36 and 37 in the operating temperature range or slightly less than that. Therefore, more frictional heat can be generated between the pinion gears 23 and 24 and the friction members 36 and 37 without excessive wear of the friction members 36 and 37.

(Examples 1-4)
FIG. 5A shows four different fastening allowance values Fi1 (for example, 0.01 mm), Fi2 (for example, 0.02 mm), and Fi3 (for example, 0.03 mm) for the friction members 36 and 37 of each coupling friction member 35. ), A differential gear device 10 of Examples 1 to 4 in which Fi4 (for example, 0.04 mm) is set, and a comparative example in which a tightening value Fi0 is 0, and an operation test is performed respectively. A difference in heat generation amount (heat generation temperature) as shown in the figure was observed.

  In addition, as shown in FIG. 5B, the fuel efficiency improvement effect increases as the lubricating oil temperature in the housing 11 increases.

  As described above, in the differential gear device 10 of the present embodiment, when the viscosity of the lubricating oil inside the housing 11 is low, the pinion gears 23 and 24 that rotate by increasing the differential of the side gears 21 and 22 and the friction member 36 are rotated. , 37 is caused to generate heat by rubbing strongly, and the temperature of the lubricating oil is quickly raised to a temperature at which the viscosity of the lubricating oil is sufficiently reduced. Therefore, the temperature rise rate of the lubricating oil is increased at a low temperature with a simple configuration. Thus, it is possible to provide a low-cost differential gear device capable of reducing the viscosity of the lubricating oil at an early stage, which can contribute to improving the fuel efficiency of the vehicle.

(Second Embodiment)
FIG. 6 shows the configuration of the differential gear device according to the second embodiment of the present invention. The differential gear device is a main part of the rear differential device of the vehicle. When rotational power is input from a drive pinion (not shown), power transmission is allowed while allowing differential to the left and right drive shafts. Is configured to do.

  As shown in FIG. 6, the differential gear device 40 of the present embodiment is rotatably supported by a differential carrier case (not shown) so as to be rotatable around the rotation center axis, and is a bearing supported by the front end side of the case. A housing 41 for inputting rotational power from the pinion is provided. The housing 41 is a differential case in which a bevel ring gear 42 that meshes with the drive pinion is fastened and fixed by a plurality of bolts 43. The housing 41 is connected to one and the other by bolts and positioning pins 47 (not shown). The case members 44 and 45 and at least one outer wall block 46 inserted between them are constituted.

  Inside the housing 41, side gears 51 and 52 (output gears) on one side and the other side located on one side and the other side in the rotation center axis direction are respectively housed and held so as to be rotatable. At least a pair, for example, a plurality of pairs (in the case of three pairs in FIG. 6) of worm wheel shafts 53 and 54 (small gears) are rotatably housed so as to be positioned around 51 and 52.

  The side gears 51 and 52 have spline teeth 51a and 52a that spline-couple inner ends of left and right drive shafts (not shown) on their inner peripheral sides, and the housing 41 includes inner ends of left and right drive shafts. Shaft hole portions 51h and 51i with lubricating grooves into which the portions are inserted are formed coaxially.

  Each pair of worm wheel shafts 53, 54 is arranged around side gears 51, 52 made of helical gears so as to rotate about an axis perpendicular to both side gears 51, 52, and a part of those axial directions, for example, The worm wheel portion 53w that is an intermediate portion in the axial direction is rotatably held inside the outer wall block 46 of the housing 41 so as to mesh with the side gears 51 and 52, and the remaining portions in the axial direction, for example, both ends in the axial direction. The spur gear portion 53s formed in the portion meshes with each other.

  On the other hand, the housing 41 is provided with thrust washers 61a, 61b, 62a, 62b that hold the side gears 51, 52 so as to be slidable and rotatable on the respective shaft end face sides, and the outer wall block 46 has a plurality of pairs. At least a pair of, for example, a plurality of pairs of substantially semi-cylindrical concave holding portions 63 and 64 are provided that rotatably store and hold the worm wheel shafts 53 and 54, respectively. Each pair of concave holding portions 63 and 64 is disposed adjacent to and corresponding to each pair of worm wheel shafts 53 and 54 that mesh with each other.

  Furthermore, between each pair of concave holding parts 63 and 64 of the housing 41 and each pair of worm wheel shafts 53 and 54 corresponding thereto, a substantially semi-cylindrical shape along the outer peripheral surface of the worm wheel shafts 53 and 54. Friction members 66 and 67 are provided.

These friction members 66 and 67 are made of a material whose linear expansion coefficient is about twice or more larger than that of the side gears 51 and 52 and the worm wheel shafts 53 and 54. Specifically, the friction members 66 and 67 are made of, for example, aluminum, and the housing 41, the side gears 51 and 52, and the worm wheel shafts 53 and 54 are made of steel each having a linear expansion coefficient of about 11 × 10 ⁻⁶ / K. is there.

  Each pair of friction members 66 and 67 among the plurality of pairs is integrally coupled to each other in the vicinity of the meshing portion of each corresponding pair of worm wheel shafts 53 and 54 (small gear pair), and is configured as a coupling friction member 65. . The coupling friction member 65 is engaged with the housing 41 and restrained in the vicinity of the coupling portion between the pair of friction members 66 and 67, and also has an inner surface portion that forms a curvature surface with a curvature radius r1 of the pair of friction members 66 and 67. The worm wheel shafts 53 and 54 are engaged.

  Further, the gap between the housing 41 and the worm wheel shafts 53 and 54 is slightly larger at both arms of the coupling friction member 65 in the circumferential direction of the curvature of the friction members 66 and 67 than at the center in this direction. ing. The inner surface radius of curvature r1 of the concave holding portions 33 and 34 of the housing 41 is a value closer to that at the higher temperature than the radius of curvature of the outer circumferential surface of the friction members 66 and 67 (the radius of curvature of the outer circumferential surface at the higher temperature). Smaller but larger than that at low temperature).

  Also in the differential gear device 40 of the present embodiment, when the temperature is low, the substantially semi-cylindrical friction members 66 and 67 of the plurality of coupled friction members 65 along the outer peripheral surfaces of the plurality of pairs of worm wheel shafts 53 and 54 have their respective curvatures. The radius r1 is contracted in a tendency to reduce, and the frictional contact area and the frictional force between the plurality of pairs of friction members 66 and 67 and the outer peripheral portions of the plurality of pairs of worm wheel shafts 53 and 54 are increased. Therefore, within a short time after the start of traveling at a low temperature when the viscosity of the lubricating oil inside the housing 41 is high, the lubricating oil is quickly heated to a temperature at which the viscosity of the lubricating oil is sufficiently reduced. The conventional problem that the fuel efficiency is lowered due to the relatively large differential resistance acting by the high-viscosity lubricant during turning of the vehicle is solved.

  Further, at high temperatures, the substantially semi-cylindrical friction members 66, 67 of each coupling friction member 65 expand with a tendency to increase the respective curvature radii r1, and the friction members 66, 67 of each coupling friction member 65 and the respective pairs are paired. The frictional contact area and frictional force between the outer peripheral portions of the worm wheel shafts 53 and 54 are reduced. Therefore, the temperature of the lubricating oil inside the housing 41 is prevented from excessively rising during continuous running.

  Therefore, even in the worm gear type torque-sensitive differential gear device as in this embodiment, the friction members 66 and 67 are disposed between the worm wheel shafts 53 and 54 (worm gear type small gears) and the housing 41. A low-cost differential gear that can achieve the same effects as those of the above-described embodiment, and can increase the temperature of the lubricating oil at a low temperature and reduce the viscosity of the lubricating oil at an early stage with a simple configuration. An apparatus can be provided.

(Third embodiment)
FIG. 7 shows the configuration of a differential gear device according to the third embodiment of the present invention. This differential gear device is of a planetary gear mechanism type, and when rotational power is input from a drive pinion (not shown), the rotation between the left and right drive shafts is allowed while allowing the differential between both shafts. It is configured to transmit power.

  As shown in FIG. 7, the differential gear device 70 of the present embodiment is rotatably supported by a transmission case (not shown) so as to be rotatable around a rotation center axis, and is mounted on the outer periphery thereof (not shown). A housing 71 for inputting rotational power from the final drive gear via a ring gear is provided. The housing 71 has an opening end 71e on one end thereof closed by a carrier member 72. The carrier member 72 is spline-coupled to the opening end 71e of the housing 71, and an opening of the housing 71 is formed by an annular screw member 73. The end 71e is secured and fixed.

  Inside the housing 71, an internal ring gear 81 (one output gear) located on one side in the rotation center axis direction and a substantially cylindrical sun gear 82 (on the other side) located on the other side in the rotation center axis direction. The output gear) and at least one, for example, a plurality of planetary pinion gears 83 (small gears) interposed between the internal ring gear 81 and the sun gear 82 are housed rotatably. These internal ring gear 81, sun gear 82, and planetary pinion gear 83 are each formed of a helical gear.

  The internal ring gear 81 includes a ring gear portion 81a in which inner teeth 81t are formed, and an output cylinder portion 81c having a spline tooth portion 81b that spline-couples the inner end portion of the drive shaft (not shown) on the inner peripheral side. Have. In addition, the sun gear 82 has a spline tooth portion 82a that spline-couples the inner ends of the left and right drive shafts (not shown). Furthermore, shaft holes 79h and 79i of the housing 71 are provided with bearings 78a and 78b for rotatably supporting the inner ends of the left and right drive shafts.

  The plurality of planetary pinion gears 83 are arranged in parallel with the internal ring gear 81 and the sun gear 82, and mesh with the internal ring gear 81 at one end in the axial direction on the outer side of the revolution radius. Engage with the sun gear 82 in substantially the entire axial direction on the side. Each of these planetary pinion gears 83 is slidably held by a plurality (at least one) of concave holding portions 74 of a substantially semi-cylindrical shape of a carrier member 72 integrated with the housing 71. The concave holding portion 74 is The support members 72 are disposed at equiangular intervals so as to be positioned between the support portions 72 p of the carrier member 72. The housing 71 is fitted with thrust washers 75, 76, 77a, 77b that hold the internal ring gear 81 and the sun gear 82 so as to be slidable and rotatable at both axial end faces.

  On the other hand, a friction member 86 formed in a substantially semi-cylindrical shape along the outer peripheral surface of the planetary pinion gear 83 is provided between each concave holding portion 74 of the housing 71 and the planetary pinion gear 83 corresponding thereto.

The friction member 86 is made of a material having a linear expansion coefficient that is about twice or more larger than that of the internal ring gear 81, the sun gear 82, and the planetary pinion gear 83, for example, aluminum. The housing 71, the internal ring gear 81, the sun gear 82 and the planetary pinion gear 83 are each made of steel having a linear expansion coefficient of about 11 × 10 ⁻⁶ / K.

  Further, the gap between the housing 71 and the planetary pinion gear 83 is slightly larger at the both arms in the circumferential direction of the curvature of the friction member 86 than at the center in this direction. The inner surface radius of curvature has a value closer to that at the time of high temperature than the radius of curvature of the outer peripheral surface of the friction member 86 at the time of low temperature.

  Also in the differential gear device 70 of the present embodiment, at the time of low temperature, the plurality of friction members 86 along the outer peripheral surface of the plurality of planetary pinion gears 83 contract with a tendency to reduce the respective radii of curvature, thereby the plurality of friction members 86. And the frictional contact area and the frictional force between the outer periphery of the planetary pinion gears 83 increase. Further, at a high temperature, the plurality of friction members 86 expand with a tendency to increase the respective curvature radii, and the friction contact area and the friction force between the plurality of friction members 86 and the outer peripheral portions of the plurality of planetary pinion gears 83 are reduced. . Therefore, the temperature of the lubricating oil inside the housing 71 is prevented from excessively rising during continuous running. Therefore, even in the planetary gear type torque-sensitive differential gear device as in the present embodiment, the friction member 86 can be disposed between each planetary pinion gear 83 and the concave holding portion 74 of the housing 71. An effect similar to that of the first embodiment of the present invention is obtained, and a low-cost differential gear device capable of quickly decreasing the viscosity of the lubricating oil by increasing the temperature rise rate of the lubricating oil at a low temperature with a simple configuration is provided. be able to.

(Fourth embodiment)
FIG. 8 shows the configuration of a differential gear device according to the fourth embodiment of the present invention. This differential gear device has a basic structure similar to that of the differential gear device 10 of the first embodiment, and each pair of a plurality of pairs of pinion gears is composed of different types of pinion gears to reduce the overall axial length. Is. Therefore, here, about the structure similar to 1st Embodiment, the code | symbol of the corresponding component in FIGS. 1-4 is demonstrated only about each pair of pinion gears.

  As shown in FIG. 8, each pair of pinion gears 93 and 94 (small gears) positioned around the side gears 21 and 22 is rotatably arranged in the concave holding portions 33 and 34 of the housing 11 (not shown in the figure). Has been.

  Each pair of pinion gears 93 and 94 is arranged around both side gears 21 and 22 and parallel to both side gears 21 and 22. Further, each pair of pinion gears 93 and 94 is coupled to the concave holding portions 33 and 34 of the housing 11 so as to mesh with the side gears 21 and 22 at a part of their axial direction, for example, one end portion in the axial direction. The members 35 are held so as to be slidable and rotatable via the member 35, and mesh with each other at their remaining axial portions, for example, the other axial end portions.

  Specifically, as shown in the figure, one pinion gear 93 of each pair of pinion gears 93, 94 includes a first gear portion 93a located on one end side in the axial direction, and the first gear portion 93a A second gear portion 93b having a similar tooth shape and positioned on the other end side in the axial direction, and a cylindrical intermediate connecting portion 93c having a smaller diameter than these connecting the first and second gear portions 93a and 93b. Has been. On the other hand, the pinion gear 94 on the other side of the pair of pinion gears 93, 94 is formed by removing the intermediate coupling portion 93c of the pinion gear 93 on one side and directly connecting the first and second gear portions 93a, 93b to one end portion 94a and the other. It has the same shape as the end portion 94b, and its axial length is shorter than that of the pinion gear 93 on one side.

  Also in the differential gear device of the present embodiment, at a low temperature, the plurality of friction members 36 and 37 of the coupling friction member 35 along the outer peripheral surfaces of the plurality of pinion gears 93 and 94 contract with a tendency to reduce the respective curvature radii. Thus, the frictional contact area and the frictional force between the plurality of friction members 36 and 37 and the outer peripheral portions of the plurality of pinion gears 93 and 94 are increased. Further, at a high temperature, the plurality of friction members 36 and 37 expand with a tendency to increase the respective curvature radii, and the friction contact area between the plurality of friction members 36 and 37 and the outer peripheral portions of the plurality of pinion gears 93 and 94 and The friction force decreases. Therefore, the temperature of the lubricating oil inside the housing 11 is prevented from excessively rising during continuous running, and the same effect as in the first embodiment can be obtained.

In each of the above-described embodiments, the friction member has a substantially semi-cylindrical shape. Good. Moreover, although aluminum (industrial aluminum) was used for the friction member, an alloy with a dissimilar metal having a similar linear expansion coefficient may be used, and a large linear expansion coefficient such as magnesium, zinc, tin, etc. It is conceivable to use other materials.
Further, the friction member and the coupling friction member can be provided with notches and holes in an arbitrary shape within a range that does not contact the outer peripheral surface of the pinion gear. Furthermore, within a range that does not impair shrinkage (deformation in the decreasing direction of the radius of curvature) and expansion (deformation in the increasing direction of the radius of curvature) according to the temperature of the friction member, for example, a wear-resistant surface coating is applied, or the surface is A heat treatment for curing may be performed. The friction member may be made of a material that changes its shape when it reaches a set temperature, such as a shape memory alloy or bimetal, but it has a larger linear expansion coefficient than the small gear in terms of material and manufacturing cost. Is good.

  Further, in each of the embodiments described above, the differential gear device is interposed between the drive shafts as the left and right wheel drive shafts. However, the difference gear device is interposed between the front and rear propulsion shafts. The present invention can also be applied to a dynamic gear device or a differential gear device interposed between a front or rear wheel drive shaft and a rear or front propulsion shaft.

  As described above, when the viscosity of the lubricating oil in the housing is low, the differential gear device according to the present invention generates heat by strongly rubbing the rotating small gear and the friction member by increasing the differential of the output gear. Since the temperature of the lubricating oil is increased to a temperature at which the viscosity of the lubricating oil is sufficiently reduced, the temperature of the lubricating oil is increased at a low temperature with a simple configuration, and the viscosity of the lubricating oil is decreased at an early stage. It is possible to provide a low-cost differential gear device that can be improved, and to improve the fuel efficiency of the vehicle. The differential gear device, particularly a torque-sensitive limited slip for a vehicle, is provided. This is useful for all differential gear devices suitable for differential devices.

10, 40, 70 Differential gear unit 11, 41, 71 Housing 12, 42 Ring gear 21, 22, 51, 52 Side gear (output gear)
21a, 22a, 51a, 52a Spline teeth 21t, 22t, 23t, 24 meshing teeth 23, 24, 93, 94 Pinion gear (small gear, small gear pair)
23a, 24a Short gear part 23b, 24b Long gear part 23c, 24c Intermediate coupling part 23e, 24e Outer peripheral surface 31, 32 Annular holding part 33, 34, 63, 64, 74 Concave holding part 35, 65 Coupling friction member 36, 37 , 66, 67, 86 Friction member 44, 45 Case member 46 Outer wall block 53, 54 Worm wheel shaft (small gear, small gear pair)
53s Spur gear portion 53w Worm wheel portion 61a, 61b, 62a, 62b, 75, 76, 77a, 77b Thrust washer 72 Carrier member 81 Internal ring gear (one side output gear)
81b, 82a Spline tooth portion 82 Sun gear (the other side output gear)
83 Planetary pinion gear (small gear)
93a First gear portion 93b Second gear portion 93c Intermediate connection portion 94 Pinion gear 94a One end portion 94b Other end portion D1, D2 Drive shaft (wheel drive shaft)
Fi1, Fi2, Fi3, Fi4 Tightening margin r1 Curvature radius

Claims (8)

A housing, an output gear on one side and the other side rotatably held inside the housing so as to be positioned on one side and the other side in the rotation center axis direction, and the output gear on the one side and the other side A differential gear device comprising: at least one small gear rotatably held inside the housing to intervene,
The housing is provided with at least one concave holding portion for rotatably holding the small gear,
Between the concave holding portion and the small gear, there is provided at least one friction member made of a material having a larger linear expansion coefficient than the small gear and formed in a divided cylindrical shape along the outer peripheral surface of the small gear. A differential gear device characterized by that.   2. The differential gear according to claim 1, wherein the friction member is disposed so as to reduce a radius of curvature when the temperature is low, while increasing a radius of curvature when the temperature is high, with respect to the outer peripheral surface of the small gear. apparatus.   The friction member is inserted at a central portion in the circumferential direction of curvature at least between the concave holding portion and the small gear with a predetermined tightening allowance. The differential gear device described. The output gear on the one side and the other side is composed of a pair of external gears,
The at least one small gear is rotatably held inside the housing so as to mesh with the output gears on the one side and the other side in a part of the axial direction, and the small gears mesh with each other at the remaining portion in the axial direction. Including pairs,
4. The at least one concave holding portion and the at least one friction member of the housing include a pair of concave holding portions and a pair of friction members corresponding to the small gear pair. The differential gear device according to claim 1. The pair of friction members is configured as a coupled friction member integrally coupled in the vicinity of the meshing portion of the small gear pair,
The coupling friction member is engaged with the housing in the vicinity of a coupling portion of the pair of friction members, and is engaged with the pair of small gears at an inner surface portion of the pair of friction members. 5. The differential gear device according to 4.   6. The differential gear device according to claim 4, wherein the pair of small gears are arranged in parallel to the output gear around the output gear on the one side and the other side.   6. The differential gear device according to claim 4, wherein the pair of small gears rotate about an axis perpendicular to the output gears on the one side and the other side. The output gears on the one side and the other side are constituted by an internal ring gear rotatably accommodated in the housing and a sun gear rotatably accommodated in the housing,
The small gear is constituted by a planetary pinion gear that is rotatably held by a carrier fixed to the housing and meshes with the internal gear and the sun gear,
The differential gear device according to any one of claims 1 to 3, wherein the concave holding portion is provided on the carrier.

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