JP2010144911A - Differential gear device for vehicle - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a differential gear device for a vehicle attaining weight reduction while suppressing the looseness of a fastener for fastening a differential case to a large-diameter gear. <P>SOLUTION: The large-diameter gear 14 is formed to be thick in wall thickness t1' near a window section 12w in comparison with the wall thickness of the other portion in a fastening section 14i related to fastening to a differential case 12. The wall thickness of a portion corresponding to a column part of the large-diameter gear 14 is thereby formed to be thin to attain weight reduction, and the wall thickness t1' near the window section 12w is formed to be thick to suitably suppress the looseness of the fastener for fastening the differential case 12 to the large-diameter gear 14. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a differential gear device for a vehicle, and more particularly to an improvement for reducing the weight of a differential case while suppressing loosening of a fastener that fastens the differential case and a large-diameter gear.

  A differential gear device for distributing engine power to front and rear or left and right drive wheels is used in the power transmission path of the vehicle. For example, the differential apparatus described in Patent Document 1 is that. Such a differential gear device includes a housing, a large-diameter gear having an outer peripheral tooth and provided in the housing, and a shell-like shape that is provided integrally with the large-diameter gear and rotates around a single axis. The differential case, a pinion gear rotatably supported around an axis perpendicular to the one axis by a pinion shaft fixed to the differential case in the differential case, and the pinion gear interposed in the differential case And a pair of side gears provided so as to be relatively rotatable about the one axis.

Japanese Utility Model Publication No. 6-67950

  However, in the conventional technology as described above, when considering the weight reduction of the differential case, loosening of the fastener that fastens the differential case and the large-diameter gear becomes a problem. The inventor of the present invention pays attention to the fact that such looseness of the fastener is caused by the slip of the joint surface, and shows how the slip of the joint surface is likely to occur when the differential case and the large-diameter gear are formed. We have pursued research, including experimental considerations, and have continued intensive research.

  The present invention has been made as a result of the above research, and the object of the present invention is to provide a vehicle differential that realizes weight reduction while suppressing loosening of a fastener that fastens a differential case and a large-diameter gear. The object is to provide a gear device.

  In order to achieve such an object, the gist of the present invention is that a large-diameter gear having outer peripheral teeth and a large-diameter gear are integrally provided by being fastened by a predetermined fastener. A differential case that rotates about a center, a pinion gear that is rotatably supported about an axis perpendicular to the one axis by a pinion shaft fixed to the differential case in the differential case, and the pinion gear interposed in the differential case A differential gear device for a vehicle having a pair of side gears that are opposed to each other and are rotatable relative to each other around the one axis, wherein the differential case is provided so as to penetrate in the thickness direction thereof. The large-diameter gear is a portion related to the fastening with the differential case, and the other portion in the vicinity of the window portion. It is characterized in that its thickness is thicker in comparison with.

  According to the research of the present inventor, in order to suppress the slip of the joint surface of the portion related to the fastening between the differential case and the large-diameter gear, it is effective to increase the thickness of the fastening portion on the large-diameter gear side. I found out that Therefore, according to the present invention, the differential case is provided with at least one window portion penetrating in the thickness direction thereof, and the large-diameter gear is in a portion related to fastening with the differential case. In the vicinity of the window portion, the thickness thereof is formed as compared with the other portions, so that the thickness of the columnar portion of the large-diameter gear is reduced and the weight is reduced. By making the wall thickness in the vicinity of the window portion of the differential case thick, it is possible to suitably suppress loosening of the fastener that fastens the differential case and the large-diameter gear. That is, it is possible to provide a vehicle differential gear device that realizes weight reduction while suppressing loosening of a fastener that fastens the differential case and the large-diameter gear.

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

  FIG. 1 is a diagram illustrating a vehicle differential gear device (differential device) 10 to which the present invention is preferably applied. The shaft center of a pinion shaft (small gear shaft) 18 and the shaft center of a drive shaft 24 are illustrated. It is sectional drawing cut | disconnected by the plane containing. As shown in FIG. 1, the differential gear device 10 is rotatable (rotatable) around a shaft center orthogonal to an input shaft shaft (not shown) via a pair of tapered roller bearings between the housing and the housing. A diff case (differential case) 12 made of, for example, cast iron that is supported, a large-diameter gear 14 that is fixed to an outer peripheral portion of the diff case 12 with a fastener 15 such as a bolt and meshes with a small-diameter bevel gear of a final reduction gear (not shown), Both ends of the differential case 12 are supported, and the pinion shaft 18 fixed to the differential case 12 by a knock pin 16 in a posture orthogonal to the rotational axis of the differential case 12 is opposed to the pinion shaft 18 with the pinion shaft 18 therebetween. A pair of side gears 20l, 20r supported by the differential case 12 so as to be rotatable (rotatable) about its axis, Can be rotated by the pinion shaft 18 by the on-shaft 18 is passed through (capable of rotating) to the support by a pair of side gears 20l, a pair of pinion gears 22 that mesh 20r respectively, are provided.

  The differential case 12 has a pair of left and right through-holes 26l and 26r formed for inserting a drive shaft 24 corresponding to the pair of left and right wheels (only the one corresponding to the right wheel is shown in FIG. 1). Is provided. Further, a fitting groove (spline groove) 28 is formed on the outer peripheral surface of the end portion of the drive shaft 24, and a fitting tooth (spline) is formed so as to mesh with the fitting groove 28 on the inner peripheral surface of the side gear 20. Teeth) 30 are formed, and the drive shaft 24 inserted into the through hole 26 is fitted into the inner peripheral side of the side gear 20 so that the fitting groove 28 and the fitting teeth 30 are engaged with each other. As a result, the relative rotation about the axis common to the side gear 20 is disabled, and the side gear 20 can be rotated integrally with the side gear 20. An annular groove 32 for fitting the snap ring 34 is formed on the outer peripheral portion at the end of the drive shaft 24, and the snap ring 34 fitted into the groove 32 is a pinion of the side gear 20. By being brought into contact with the end portion on the shaft 18 side and being brought into contact with the side wall of the groove portion 32 of the drive shaft 24, the relative position change in the axial direction of the side gear 20 and the drive shaft 24 is suppressed, and the drive shaft 24 Is configured not to come out of the side gear 20.

  Further, in the differential gear device 10, a pair of washers (washers) 36 each having an annular shape are formed between the end surfaces of the pair of side gears 20l and 20r and the inner opening edges of the through holes 26l and 26r of the differential case 12 that support the end gears. It is inserted in between. A convex disk washer (washer) 38 that is partially spherical and has a hole through which the pinion shaft 18 passes in the center is provided between the outer peripheral side end surfaces of the pair of pinion gears 22 and the inner wall surface of the differential case 12. It is inserted. The washers 36 and 38 are made of a wear-resistant metal, for example, a lead-based or Sn-based bearing metal, or a metal obtained by further adding spring properties to the alloy as required.

  FIG. 2 is a front view of the differential gear device 10 of this embodiment as viewed in the direction indicated by the arrow II in FIG. FIG. 3 is a side view of the differential gear device 10 viewed in the direction indicated by the arrow II in FIG. As shown in FIG. 3, the differential case 12 is formed with a window portion 12w penetrating in the thickness direction. Preferably, a pair of window portions 12w are provided on the side peripheral portion (cylindrical portion) of the differential case 12 so as to face each other about the axis C. In other words, as shown in FIG. 2, when the side peripheral portion of the differential case 12 is divided into four in the rotation direction around the axis C, the respective portions are alternately arranged with the window portion 12 w and the window portion 12 w. This corresponds to the column portion 12p where no is provided. The window portion 12w does not necessarily correspond to 45 ° in the rotation direction, and may correspond to an angle of less than 45 ° or more.

  In the differential gear device 10 configured as described above, for example, the output from the drive system is decelerated by a final reduction gear (not shown) and transmitted to the differential case 12 via the large-diameter gear 14. When the differential case 12 is rotated about the axis of the side gear 20 (the axis of the drive shaft 24), the rotational driving force of the differential case 12 is torqued to the pair of left and right side gears 20l and 20r via the pinion gear 22. It is distributed and transmitted, and is transmitted to the drive shaft 24 that is rotated integrally with the side gears 20.

  Next, the examination of the loosening of the fastener 15 that fastens the differential case 12 and the large-diameter gear 14 performed by the present inventor and the experimental results related to the loosening will be described with reference to FIGS. FIG. 4 is a view for explaining a torque transmission path in a joint portion between a flange 12f (a fastening portion with the large-diameter gear 14) provided to project to the outer peripheral side of the differential case 12 and the large-diameter gear 14. As shown in FIG. As shown in FIG. 4, as a route of torque transmitted from the large-diameter gear 14 side to the flange 12f side of the differential case 12, a route A transmitted via the fastener 15, the differential case 12, and A path B transmitted through the joint surface of the large-diameter gear 14 is conceivable.

  Here, consider the fastening portion between the differential case 12 and the large-diameter gear 14 as shown in FIG. The differential case 12 and the large-diameter gear 14 include a plurality of flange portions 12f that project to the outer peripheral side of the differential case 12 and fastening portions 14i that project to the inner peripheral side of the large-diameter gear 14. The fasteners 15 (12 in FIG. 3) are screwed together and fastened. In this discussion and experiment, paying attention to the thickness (axial thickness dimension) t1 and t2 of the flange portion 12f of the differential case 12 and the fastening portion 14i of the large-diameter gear 14, the thicknesses t1 and t2 are changed. In this case, the effect of suppressing the loosening of the fastener 15 was examined.

  FIG. 6 is a diagram showing the torque sharing rate of the joint surface when the thickness (thickness dimension) of the fastening portion 14 i of the large-diameter gear 14 is changed. The torque sharing ratios shown in FIG. 6 correspond to the paths A and B shown in FIG. 4, respectively, and the ring A × bolt is transmitted via the fastener 15 and the ring gear × flange is the differential case 12 and Each corresponds to a path B transmitted through the joint surface of the large-diameter gear 14. As shown in FIG. 6, when the thickness t1 of the fastening portion 14i of the large-diameter gear 14 is changed, the torque sharing of the path A transmitted through the fastener 15 is increased as the thickness t1 is increased. It can be seen that the ratio decreases, and conversely, the torque sharing ratio of the path B transmitted through the joint surface of the differential case 12 and the large-diameter gear 14 increases.

  7 and 8 are diagrams showing the relationship between the surface pressure and the frictional force of the joint surface when the thickness (thickness dimension) t1 of the fastening portion 14i of the large-diameter gear 14 is changed, and FIG. FIG. 8 shows the relationship in the vicinity, and FIG. 9 and 10 are diagrams showing the relationship between the surface pressure and the frictional force at the joint surface between the fastening portion 14i of the large-diameter gear 14 and the flange 12f of the differential case 12, and FIG. FIG. 10 shows the local slip when the thickness t2 of the flange 12f of the differential case 12 is changed. Respectively. 7 to 10 also show that the case where the thickness t2 of the flange 12f of the differential case 12 is increased when the thickness t1 of the fastening portion 14i of the large-diameter gear 14 is increased. It can be seen that the decrease in the slip amount of the joint surface is greater than that. That is, in order to suppress slippage of the joint surface between the flange 12f and the fastening portion 14i, increasing the thickness t1 of the fastening portion 14i is more effective than increasing the thickness t2 of the flange 12f. You can see that

  11 and 12 show the effect of suppressing slippage of the joint surface when the thickness t1 of the fastening portion 14i of the large-diameter gear 14 is changed and when the thickness t2 of the flange 12f of the differential case 12 is changed. It is a figure explaining the consideration result of the reason which is different. As shown in FIG. 11, when the wall thickness t1 of the fastening portion 14i of the large-diameter gear 14 is changed (increased), the contact area between the fastening portion 14i and the flange 12f increases, and these differential cases 12 and the sharing ratio of torque (corresponding to the path B in FIG. 4) transmitted through the joint surface of the large-diameter gear 14 increases. Thereby, between the said fastening part 14i and the flange 12f, the result of sliding on the flange 12f uniformly arises in the vicinity of the meshing point of the fastening part 14i and a distant place. Thereby, it is considered that the frictional force is made uniform (averaged), the maximum slip amount is reduced, and as a result, the slip on the joint surface is suppressed. Moreover, between the said fastening part 14i and the fastener 15, the torque sharing rate reduces relatively and the slip amount becomes small. On the other hand, as shown in FIG. 12, when the thickness t2 of the flange 12f of the differential case 12 is changed (increased), the torque sharing ratio between the fastening portion 14i and the flange 12f does not change, and the slip Little change in quantity. As a result, between the fastening portion 14i and the flange 12f, the elastic deformation of the flange 12f decreases in the vicinity of the meshing and the contact area increases, and the torque sharing rate increases. As a whole, it is considered that there is little change in the sliding state. Further, since the torque sharing ratio does not change between the fastening portion 14i and the fastener 15, the slip amount does not change. Also from the result of such consideration, in order to suppress slippage of the joint surface between the flange 12f and the fastening portion 14i, it is possible to increase the thickness t2 of the flange 12f by increasing the thickness t1 of the fastening portion 14i. You can conclude that it is more effective than thickening.

  Based on the above considerations and experimental results, the configuration provided in the differential gear device 10 of the present embodiment will be described with reference to FIGS. 13 and 14. 13 and 14 are partial cross-sectional views showing a portion related to the fastening of the flange 12f of the differential case 12 and the fastening portion 14i of the large-diameter gear 14, and FIG. 13 corresponds to the column portion 12p of the differential case 12. FIG. 14 shows a configuration corresponding to the portion corresponding to the window portion 12w of the differential case 12, respectively. As shown in FIG. 13 and FIG. 14, in the differential gear device 10 of the present embodiment, a portion corresponding to the window portion 12 w of the differential case 12 in the fastening portion 14 i of the large-diameter gear 14, that is, the vicinity of the window portion 12 w. In this case, the thickness (axial thickness dimension) t1 ′ is thicker than the other portion, that is, the portion corresponding to the column portion p (t1 <t1 ′). In other words, in the portion other than the portion corresponding to the window portion 12w of the differential case 12, the thickness t1 is formed thinner than the portion corresponding to the window portion 12w. As described above, by configuring a part of the fastening portion 14i of the large-diameter gear 14 to be thin, it is possible to reduce the weight of the large-diameter gear 14 and the differential gear device 10 as a whole. Further, in the vicinity of the window portion 12w of the differential case 12 where relatively strong strength is required, the fastening portion 14i of the large-diameter gear 13 is configured to be relatively thick, so that the required strength can be ensured and the large-diameter gear. Thus, the effect of suppressing the slippage of the joint surface due to the increase in the thickness of 14 can be expected, and further, the effect of suppressing the looseness of the fastener 15 that fastens the differential case 12 and the large-diameter gear 14 can be realized.

  Thus, according to the present embodiment, the differential case 12 includes at least one window portion 12w provided so as to penetrate in the thickness direction, and the large-diameter gear 14 is connected to the differential case 12. In the fastening portion 14i related to fastening, the thickness t1 'is formed thicker in the vicinity of the window portion 12w than the thickness t1 of the other portion. The thickness t1 in the portion corresponding to the column portion 12p is reduced to reduce the weight, and the thickness t1 'in the vicinity of the window portion 12w is increased to increase the thickness of the differential case 12 and the large-diameter gear 14. The looseness of the fastener 15 that fastens can be suitably suppressed. That is, it is possible to provide the vehicle differential gear device 10 that realizes weight reduction while suppressing loosening of the fastener 15 that fastens the differential case 12 and the large-diameter gear 14.

  The preferred embodiments of the present invention have been described in detail with reference to the drawings. However, the present invention is not limited to these embodiments, and various modifications can be made without departing from the spirit of the present invention. Is.

BRIEF DESCRIPTION OF THE DRAWINGS It is a figure explaining the differential gear apparatus for vehicles with which this invention is applied suitably, Comprising: It is sectional drawing cut | disconnected by the plane containing the axial center of a pinion shaft, and the axial center of a drive shaft. FIG. 2 is a front view of the vehicle differential gear device of FIG. 1 viewed in a direction indicated by an arrow II. FIG. 3 is a side view of the vehicle differential gear device of FIG. 2 viewed in a direction indicated by an arrow II. It is a figure explaining the torque transmission path | route in the junction part of the flange of a differential case and the large diameter gear in the differential gear device for vehicles of FIG. FIG. 2 is a partial cross-sectional view showing a portion related to fastening between a flange of a differential case and a fastening portion of a large-diameter gear in the vehicle differential gear device of FIG. 1. It is a figure which shows the torque sharing rate of the joint surface at the time of changing the thickness of the fastening part of the large diameter gear in the differential gear device for vehicles of FIG. FIG. 2 is a diagram illustrating a relationship between a surface pressure and a frictional force of a joint surface when the thickness of a fastening portion of a large-diameter gear in the vehicle differential gear device in FIG. 1 is changed, and shows a relationship in the vicinity of meshing. It is a figure which shows the relationship of the surface pressure and frictional force of a joint surface at the time of changing the thickness of the fastening part of the large diameter gear in the vehicle differential gear apparatus of FIG. It is a figure which shows the relationship between the surface pressure and frictional force in the joint surface of the fastening part of a large diameter gear and the flange of a differential case in the differential gear device for vehicles of FIG. 1, and changed the thickness of the fastening part of a large diameter gear The local slip in the case is shown. FIG. 2 is a diagram illustrating a relationship between a surface pressure and a frictional force at a joint surface between a fastening portion of a large-diameter gear and a flange of a differential case in the differential gear device for a vehicle in FIG. 1, and a locality when the thickness of the flange of the differential case is changed. Shows slipping. Consideration of the reason why the slip suppression effect of the joint surface is different between the case where the thickness of the fastening portion of the large-diameter gear in the vehicle differential gear device of FIG. 1 is changed and the case where the thickness of the flange of the differential case is changed. It is a figure explaining a result and shows the case where the thickness of the fastening part of a large-diameter gear is changed. Consideration of the reason why the slip suppression effect of the joint surface is different between the case where the thickness of the fastening portion of the large-diameter gear in the vehicle differential gear device of FIG. 1 is changed and the case where the thickness of the flange of the differential case is changed. It is a figure explaining a result and shows the case where the thickness of the flange of a differential case is changed. FIG. 2 is a partial cross-sectional view showing a portion related to fastening between a flange of a differential case and a fastening portion of a large-diameter gear in the differential gear device for a vehicle of FIG. 1, and shows a configuration corresponding to a portion corresponding to a pillar portion of the differential case. . FIG. 2 is a partial cross-sectional view showing a portion related to fastening between a flange of a differential case and a fastening portion of a large-diameter gear in the differential gear device for a vehicle in FIG. 1, and shows a configuration corresponding to a portion corresponding to a window portion of the differential case. .

Explanation of symbols

10: Vehicle differential gear device 12: Differential case 12w: Window portion 14: Large diameter gear 15: Fastener 18: Pinion shaft 20: Side gear 22: Pinion gear

Claims (1)

A large-diameter gear having outer peripheral teeth, a differential case that is integrally provided with the large-diameter gear by being fastened by a predetermined fastener, and rotates around a single axis, and is fixed to the differential case in the differential case A pinion gear supported by a pinion shaft so as to be rotatable about an axis perpendicular to the one axis, and opposite to each other with the pinion gear interposed in the differential case and provided so as to be relatively rotatable about the one axis. A differential gear device for a vehicle comprising a pair of side gears,
The differential case is provided with at least one window provided so as to penetrate in the thickness direction thereof,
The differential gear for vehicles is characterized in that the large-diameter gear is formed thicker in the portion related to the fastening with the differential case in the vicinity of the window than in the other portions. apparatus.

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