JP3641503B2 - Differential device - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to a vehicle differential apparatus.
[0002]
[Prior art]
A differential apparatus 201 as shown in FIG. 6 is described in Japanese Utility Model Laid-Open No. 6-43401. The differential device 201 includes a differential case 203, long and short helical pinion gears 205 and 207, and output-side helical side gears 209 and 211, and the helical pinion gears 205 and 207 slide in the storage holes 213 and 215 of the differential case 203. It is housed in a freely rotating manner. The driving force of the engine that rotates the differential case 203 is transmitted from the helical pinion gears 205 and 207 to the wheel side via the side gears 209 and 211.
[0003]
While transmitting torque, each of the helical pinion gears 205 and 207 is pressed against the wall surface of the storage holes 213 and 215 by the reaction force of the meshing with the helical side gears 209 and 211 to generate frictional resistance and meshing with the helical gear. The thrust force causes frictional resistance between the helical side gears 209 and 211, or between the helical pinion gears 205 and 207 or the helical side gears 209 and 211 and the differential case 203, and differential limiting force is obtained by these frictional resistances. .
[0004]
[Problems to be solved by the invention]
The differential device, after setting the oil inside the differential case to a low temperature where the oil flow is poor and giving the differential rotation speed and the input torque to a predetermined value, after giving the differential rotation corresponding to the left and right turn of the vehicle several cycles, An anti-seizure test is conducted to disassemble and inspect the sliding parts for burns and galling. As a result, it was discovered that the short helical pinion gear was worn only at the center in the axial direction and was worn only at both ends.
[0005]
This cause is analyzed as follows.
[0006]
FIG. 7 is a cross-sectional view of the differential device 201, and the short helical pinion gear 207 is disposed so as to revolve following the rotation direction 200 of the differential case 203 of the differential device 201 during forward movement. FIG. 8 shows a meshing portion between the short helical pinion gear 207 and the helical side gear 211, and a meshing portion between the short helical pinion gear 207 and the long helical pinion gear 205. FIG. 8 is a side view of the short helical pinion gear 207 viewed from the Y direction in FIG. A tooth trace 219 and the like are shown. FIG. 9 shows an end face of the helical pinion gear 207. The left half of FIG. 9 is the end face in the A direction in FIG. 8, and the right half is the end face in the B direction in FIG. EA and EB in FIGS. 8 and 9 indicate axial ends of a portion receiving the force F (FIG. 7) due to rotation of the differential case 203 (contact portion with the differential case 203), and N indicates a central portion in the axial direction. .
[0007]
As shown in FIG. 7, when the vehicle travels forward (in the direction of the arrow 217), the helical pinion gear 207 receives the force F from the wall surface of the storage hole 215 by the rotation of the differential case 203 and presses the helical side gear 211 and the helical pinion gear 205. From these, the reaction forces f1 and f2 are received. As shown in FIG. 8, since the reaction forces f1 and f2 are different in the axial position of the point of action, forces 221 and 221 centering on the middle point N act on the helical pinion gear 207, and the end portions EA and EB are caused by the moment. Acts in the direction of arrows 223 and 225 in FIG. Thus, the helical pinion gear 207 falls in the direction in which the twist angle θ of the tooth trace 219 decreases as shown by the broken line 227 in FIG. 8, and the helical pinion gear 207 is between the tooth tip of the helical pinion gear 207 and the wall surface of the storage hole 215 as shown in FIG. However, the driving torque to the differential case 203 is input from the wall surface of the storage hole over the entire length of the pinion gear 207, and the pinion gear 207 receives a high reaction force at each meshing portion and abuts against the wall surface of the storage hole 215.
[0008]
Here, the gap x is calculated according to the example of FIG.
[0009]
In this example, if the tooth width excluding the chamfered portion of the helical pinion gear 207 is Lmm and the twist angle is θ °,
The circumferential length from the end EA to the end EB is:
L × tan θ,
The length in the circumferential direction from each end EA, EB to the middle point N is ½ thereof.
[0010]
Furthermore, if the angle formed by each end EA, EB and the center O is α,
[Expression 1]
α = ((L × tan θ) / 2) / (θ × π) × 360 (1)
[0011]
Next, assuming that the displacement of each end EA, EB due to the falling of the helical pinion gear 207 is δ mm, and the gap formed between the helical pinion gear 207 and the wall surface of the storage hole 215 is x,
x = sin α ° × δ mm (2)
[0012]
As shown in FIG. 10, this gap xmm is a gap at each end EA, EB of the tooth trace 219, and the closer to the middle point N from each end EA, EB, the smaller α in the equation (1) In equation (2), the gap x is narrowed, and the gap x at the midpoint N is zero. Therefore, when the vehicle travels forward, the tooth tip of the helical pinion gear 207 wears when the vicinity of the midpoint N abuts or slides on the wall surface of the storage hole 215. That is, when the driving torque is input to the differential case 203, the contact edge of the pinion gear 207 received by the axial length of the wall surface of the storage hole 215 is shortened by the reduction of the twist angle due to the above-described tilting. A contact or sliding contact with the wall surface of the pinion gear 207 makes it impossible to obtain uniform contact over the entire tooth width of the pinion gear 207, and wear increases as the input torque increases.
[0013]
When the vehicle travels backward, the reaction forces f1 and f2 in FIGS. 7 and 8 work in opposite directions, and the helical pinion gear 207 falls in the opposite direction to that in forward traveling by the forces 229 and 229 in FIG. Therefore, the gap x becomes wider near the middle point N and becomes 0 at each end EA, EB. Therefore, the wear proceeds near the end portions EA and EB that strongly contact the wall surface of the storage hole 215.
[0014]
FIG. 11 shows a short helical pinion gear 233 in which the direction of the tooth trace 231 is formed opposite to the helical pinion gear 207. Note that the short helical pinion gear 233 is also disposed so as to revolve following the rotation direction 200 of the differential case 203 of the differential device 201 in the same manner as the pinion gear 207 described above. In this case, when the vehicle travels forward, the tooth trace 231 receives forces 235 and 235 due to the reaction forces f1 and f2 and falls in a direction in which the twist angle θ of the tooth trace 231 increases as indicated by a broken line 237, and the vehicle moves backward. When the vehicle travels, it receives forces 239 and 239 in opposite directions and falls in a direction in which the twist angle θ decreases. Therefore, as shown in FIG. 12, during the forward travel, the gap x becomes wider near the middle point N as in the reverse travel of the vehicle in the above example, and the entire pinion gear 233 is against the wall surface of the storage hole. Even contact with the tooth width cannot be obtained, and the vicinity of the end portions EA and EB that are strongly in contact with the wall surface of the storage hole 215 is worn, and at the time of reverse travel, the vicinity of the middle point N is the same as during forward travel in the above example. Wear out.
[0015]
As described above, the wear of the helical gear occurs at different portions depending on the direction of the tooth trace and the traveling direction of the vehicle.
[0016]
SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a differential device that is composed of a helical gear and that significantly reduces uneven wear and seizure of the gear.
[0017]
[Means for Solving the Problems]
The differential device according to claim 1 includes a differential case that is rotationally driven by the driving force of the engine, a pair of output-side helical side gears, and first and second gear portions, and the first gear portion meshes with one helical side gear. A helical pinion gear, a helical pinion gear having first and second gear portions, the first gear portion meshing with the other helical side gear, and the second gear portion meshing with each other, and a differential case The helical pinion gear is formed so as to accommodate the helical pinion gear so that the helical pinion gear can be slidably rotated. If smaller, successive tooth height of the pinion gear toward the axial center portion of the helical pinion gear than a tooth height of the end portions Characterized by being formed so as to be lower Te.
[0018]
The differential device according to claim 2 is configured such that the tooth height of the pinion gear is greater than the tooth height at both ends toward the axially central portion of the pinion gear that revolves backward and revolves in the rotation direction of the differential case when the vehicle travels forward. 2. The differential apparatus according to claim 1, wherein the differential apparatus is formed so as to be continuously lowered .
[0019]
The differential device according to claim 3 includes a differential case that is rotationally driven by the driving force of the engine, a pair of output side helical side gears, and a first and second gear portion, and the first gear portion is one of the helical side gears. A pinion gear set having first and second gear portions, the first gear portion meshing with the other helical side gear, and each second gear portion meshing with each other, The first and second gear portions receive a twisting angle of a tooth line that contacts the storage hole in the helical pinion gear when the vehicle is running. If it increased by the force, tooth height of the pinion gear toward the axial center portion of the helical pinion gear than a tooth height of the end portions Characterized by being formed so as to be higher continue to.
[0020]
The differential apparatus according to claim 4 is configured such that the tooth height of the pinion gear is greater than the tooth height at both ends toward the axially central portion of the pinion gear that revolves backward and revolves with respect to the rotation direction of the differential case when the vehicle travels forward. 4. The differential apparatus according to claim 3, wherein the differential apparatus is formed so as to be continuously high .
[0021]
[Action]
In the differential device according to the first aspect, the helical pinion gear falls down in the direction in which the torsion angle of the tooth line contacting the storage hole is reduced by the reaction force received by the first and second gear portions when the vehicle is traveling. In order to prevent excessive contact, the tooth height of the central part of the helical pinion gear is formed continuously lower than the tooth height of both ends, so that the tooth tip and the storage hole are evenly contacted at the full tooth width. I am letting. Therefore, uneven wear or seizure does not occur over the entire tooth width of the helical pinion gear.
[0022]
The differential device according to claim 2 is the differential device according to claim 1, wherein the tooth height at the axially central portion of the pinion gear that revolves backward in the pinion gear set with respect to the rotation direction of the differential case when the vehicle travels forward is set at both ends. The tooth tip of the helical pinion gear, which is continuously lower than the tooth height, is designed to be in uniform contact with the storage hole, effectively preventing uneven wear and seizure during forward travel where a larger torque is applied than during reverse travel. Can be prevented.
[0023]
In the differential device according to the third aspect, the helical pinion gear falls in the direction in which the torsion angle of the tooth line contacting the storage hole is increased by the reaction force received by the first and second gear portions during traveling of the vehicle. To prevent excessive contact, the tooth height at both ends of the helical pinion gear is formed continuously lower than the tooth height at the center, so that the tooth tip and the storage hole are evenly contacted at the full tooth width. I am letting. Therefore, uneven wear or seizure does not occur over the entire tooth width of the helical pinion gear.
[0024]
A differential apparatus according to a fourth aspect is the differential apparatus according to the third aspect, wherein the tooth height at the axially central portion of the pinion gear that revolves backward in the pinion gear set with respect to the rotational direction of the differential case when the vehicle is traveling forward is provided at both ends. The tooth tip of the helical pinion gear, which is continuously higher than the tooth height of the gear, is designed to be in uniform contact with the storage hole, effectively preventing uneven wear and seizure during forward travel where a larger torque is applied than during reverse travel. Can be prevented.
[0025]
【Example】
A first embodiment of the present invention will be described with reference to FIGS. This embodiment has the features of claims 1 and 2. FIG. 1 shows a longitudinal section of the embodiment, and FIG. 2 shows its gear set. The left and right directions are the left and right directions in FIG. In addition, the member etc. which are not giving the code | symbol are not illustrated.
[0026]
As shown in FIG. 1, the differential case 21 of the differential device 7 that is rotationally driven by the driving force of the engine is configured by fixing a casing body 31 and a cover 33 with bolts 35. Left and right helical side gears 37 and 39 (a pair of output side helical side gears) are arranged inside the differential case 21.
[0027]
The hollow boss portions 41 and 43 of the side gears 37 and 39 are rotatably supported by the support portions 45 and 47 of the differential case 21. Thrust blocks 53 are arranged on the large-diameter portions 49 and 51 formed inside the boss portions 41 and 43 so as to straddle the inner peripheries thereof, and the free ends of the side gears 37 and 39 are supported and centered. ing.
[0028]
The left and right rear axles (not shown) pass through the boss portions 55 and 57 of the differential case 21 and are splined to the boss portions 41 and 43 of the side gears 37 and 39, and are attached to each other via the thrust block 53. Yes. A thrust washer 59 is disposed between the side gears 37 and 39 and the differential case 21, and a thrust washer 61 is disposed between the side gears 37 and 39 (on the outer peripheral side of the thrust block 53).
[0029]
A plurality of long and short storage holes 63 and 65 are formed in the differential case 21 in the circumferential direction. Long and short helical pinion gears 67 and 69 are housed in these housing holes 63 and 65 so as to be slidable and rotatable.
[0030]
The long pinion gear 67 includes first and second gear portions 71 and 73 and a small-diameter shaft portion 75 that connects them, and the first gear portion 71 meshes with the right side gear 39. The short pinion gear 69 includes first and second gear portions 77 and 79, the first gear portion 77 meshes with the left side gear 37, and the second gear portion 79 meshes with the second gear portion 73 of the pinion gear 67. ing.
[0031]
As shown in FIG. 1, openings 81, 83, 85 are provided in the differential case 21, and spiral oil grooves 87, 87 are formed on the inner circumferences of the boss portions 55, 57. When the rear differential 7 rotates, the oil repelled from the oil reservoir flows into the differential case 21 through these openings 81, 83, 85 and oil grooves 87, 87, and engages the meshing portions of the gears and the sliding portions. Lubricate.
[0032]
The driving force of the engine that rotates the differential case 21 is distributed from the pinion gears 67 and 69 to the left and right rear wheels 13 and 15 via the side gears 37 and 39. Further, if a driving resistance difference occurs between the rear wheels due to one wheel idling on a rough road, the driving force of the engine is differentially distributed to the left and right sides by the rotation of the pinion gears 67 and 69.
[0033]
During the transmission of torque, the tooth tips of the pinion gears 67 and 69 are pressed against the wall surfaces of the storage holes 63 and 65 by the meshing reaction force with the side gears 37 and 39 to generate frictional resistance. In addition, frictional resistance is generated between the end faces of the pinion gears 67 and 69 and the differential case 21 by the meshing thrust force of the helical gear, and between the side gears 37 and 39 and the differential case 21 via the thrust washer 59, and the thrust washer 61. Friction resistance is generated between the side gears 37 and 39 via the. These frictional resistances provide a torque sensitive differential limiting function.
[0034]
The tooth lines of the gear portions 71, 73, 77, 79 of the pinion gears 67, 69 are formed in the direction as shown in FIG. An arrow 89 indicates the direction of rotation of the differential case 21 when the vehicle travels forward. At that time, the short pinion gear 69 that revolves and revolves with respect to the rotational direction 89 of the differential case 21 is a force F from the wall surface of the storage hole 65. (Same as the force F in FIG. 7) is pressed against the second gear portion 73 of the pinion gear 67 and the left side gear 37.
[0035]
As described above with reference to FIGS. 7 to 10, this is a state in which the pinion gear 69 is tilted in a direction in which the torsion angle θ of the tooth streak is reduced when the vehicle is traveling forward, and the center portion strongly contacts the storage hole 65. Thus, as shown in FIG. 3, the tooth height hN at the center of the pinion gear 69 is formed continuously lower than the tooth heights hEA and hEB at both ends. In this embodiment, the difference between the tooth height hN and the tooth heights hEA and hEB corresponds to the size of the support gap between the pinion gear 69 and the storage hole 63, and is set to 0.03 mm. Therefore, the difference dimension varies depending on the dimensions of the pinion gear 69 of the differential device 7 and the storage hole 65 of the differential case 21, but can be easily set by tooth surface polishing. Therefore, the pinion gear 69 comes into uniform contact with the tooth tip and the storage hole 65 over the entire tooth width during forward travel where a greater force is applied during reverse travel, and uneven wear and seizure are prevented.
[0036]
Thus, the differential device 7 is configured.
[0037]
When the differential device 7 is applied to a vehicle, the behavior of the vehicle body when a large torque is applied, such as when starting or accelerating, is stabilized by the torque-sensitive differential limiting function and the maneuverability is improved.
[0038]
As described above, since the differential device 7 has the tooth height at the center portion of the short helical pinion gear 69 that strongly contacts the storage hole 65 lower than the tooth height at both ends during forward traveling of the vehicle where a large force is applied, Therefore, the tooth tip and the storage hole 65 are in uniform contact with each other, and uneven wear and seizure do not occur.
[0039]
Next, a second embodiment will be described with reference to FIGS. This embodiment has the features of claims 3 and 4. FIG. 4 shows the gear portion used in this embodiment. In this embodiment, members having the same functions as those in FIG. 1 are referred to by the same reference numerals, and description of these members having the same functions is omitted.
[0040]
As shown in FIG. 4, the gear portion includes a pair of output side helical side gears 91 and 93 and a plurality of sets of long and short helical pinion gears 95 and 97. The side gears 91 and 93 are rotatably supported on the differential case 21.
[0041]
The long pinion gear 95 includes first and second gear portions 99 and 101 and a small-diameter shaft portion 103 that connects the first and second gear portions 99 and 101, and the first gear portion 99 meshes with the side gear 93. The short pinion gear 97 includes first and second gear portions 105 and 107, the first gear portion 105 meshes with the side gear 91, and the second gear portion 107 meshes with the second gear portion 101 of the pinion gear 95. .
[0042]
The tooth lines of the gear portions 99, 101, 105, and 107 of the pinion gears 95 and 97 are formed in directions as shown in FIG. An arrow 109 indicates the rotation direction of the differential case 21 when the vehicle travels forward. At this time, the short pinion gear 97 that revolves and revolves with respect to the rotation direction 109 of the differential case 21 is a force F from the wall surface of the storage hole 65. (Same as the force F in FIG. 7) is pressed against the second gear portion 101 and the side gear 91 of the pinion gear 95.
[0043]
As described above with reference to FIGS. 11 and 12, this is because the pinion gear 97 is tilted in the direction in which the torsion angle θ of the tooth is increased when the vehicle is traveling forward, and both end portions are in strong contact with the receiving hole 65. As shown in FIG. 5, the tooth heights hEA and hEB at both ends of the pinion gear 97 are formed continuously lower than the tooth height hN at the center. In this embodiment, the difference between the tooth height hN and the tooth heights hEA and hEB corresponds to the size of the support gap between the pinion gear 69 and the storage hole 63, and is set to 0.03 mm. Therefore, the difference dimension varies depending on the dimensions of the pinion gear 69 of the differential device 7 and the storage hole 65 of the differential case 21, but can be easily set by tooth surface polishing. Therefore, the pinion gear 97 comes into uniform contact with the tooth hole and the storage hole 65 with the full tooth width during forward travel where a greater force is applied during reverse travel, thereby preventing uneven wear and seizure.
[0044]
In the first and second embodiments described above, in the short helical pinion gears 69 and 97 as shown in FIGS. 2 and 4, a line 100 parallel to the rotation axis of these pinion gears 96 and 97 is connected to the pinion gear 69. , 97 facing the tooth tips, there is a contact point P with the short receiving hole 65, but this contact point P moves in the axial direction by the rotation of the pinion gears 69, 97. When this contact P is offset toward one end in the axial direction, the pinion gears 69 and 97 themselves are greatly tilted by the reaction force applied to the first and second gear portions 77 and 79, so that the contact with the receiving hole 65 becomes strong. That is, regardless of whether the number of contact points (contact points resulting from the length of the pinion gear and the torsion angle of the pinion gear) between the tooth tips of the pinion gears 69 and 97 and the twisting angle of the pinion gear is small or offset, the present proposal The tooth tip and the accommodation hole 65 can be uniformly contacted over the entire tooth width.
[0045]
As described above, the differential device of the present invention is used for a rear differential (rear wheel side axle differential), a front differential (front wheel side axle differential), and a center differential (a differential device that distributes driving force to the front wheels and the rear wheels).
[0046]
【The invention's effect】
In the differential device according to claim 1, the helical pinion gear falls down in a direction in which the twist angle of the streak contacting the storage hole is reduced by the reaction force received by the first and second gear portions when the vehicle is running, In order to prevent the occurrence of hitting, the tooth height of the central portion of this helical pinion gear is formed continuously lower than the tooth height of both ends, the tooth tip and the storage hole are uniformly contacted over the entire tooth width, Prevents uneven wear and seizure.
[0047]
In the differential device according to claim 3, the helical pinion gear falls in a direction in which the torsion angle of the tooth line contacting the storage hole is increased by the reaction force received by the first and second gear portions during traveling of the vehicle. In order to prevent hitting, the tooth height at both ends of the helical pinion gear is formed to be continuously lower than the tooth height at the center, and the tooth tips and the storage holes are uniformly contacted over the entire tooth width. It prevents wear and seizure.
[0048]
According to a second aspect and a fourth aspect of the present invention, in the differential device according to the first and third aspects, the helical pinion gear teeth that revolve backward in the pinion gear set with respect to the rotation direction of the differential case when the vehicle travels forward. The tip is in uniform contact with the storage hole, and uneven wear and seizure can be effectively prevented during forward travel in which a larger torque is applied than during reverse travel.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a first embodiment of the present invention.
FIG. 2 is a perspective view of a gear portion used in the first embodiment.
FIG. 3 is a cross-sectional view of a short helical pinion gear used in the first embodiment.
FIG. 4 is a perspective view of a gear portion used in a second embodiment of the present invention.
FIG. 5 is a cross-sectional view of a short helical pinion gear used in the second embodiment.
FIG. 6 is a cross-sectional view of a conventional example.
7 is a cross-sectional view of the conventional example of FIG.
FIG. 8 is a side view for explaining the falling of the helical pinion gear.
FIG. 9 is an end view for explaining the fall of the helical pinion gear.
FIG. 10 is a cross-sectional view showing a difference in gap amount between each portion of the storage hole and the helical pinion gear.
11 is a side view for explaining the tilting of the helical pinion gear having a twist angle direction different from that of FIG. 8. FIG.
12 is a cross-sectional view showing a difference in gap amount between each portion of the storage hole and the helical pinion gear in the example of FIG.
[Explanation of symbols]
7 Differential device 21 Differential case 37, 39, 91, 93 Output side helical side gear 63, 65 Storage hole 67, 95 Long helical pinion gear (helical pinion gear)
69,97 Short helical pinion gear (helical pinion gear)
71, 77, 99, 105 First gear portion 73, 79, 101, 107 Second gear portion hN Central height tooth height hEA, hEB End height tooth height

Claims (4)

A differential case that is rotationally driven by the driving force of the engine; a pair of output-side helical side gears; a helical pinion gear that has first and second gear portions and the first gear portion meshes with one helical side gear; A pinion gear set having a second gear portion, the first gear portion meshing with the other helical side gear, and each second gear portion meshing with each other, and sliding on each helical pinion gear formed in the differential case The helical pinion gear has a housing hole that is rotatably accommodated, and the helical pinion gear has a helical pinion gear that has a helical twisting angle that is in contact with the housing hole when the helical pinion gear is traveling. JP that toward the axially central portion is tooth height of the pinion gear is formed to be lower in succession from the tooth height of the end portions Differential device to. Formed so that the tooth height of the pinion gear is continuously lower than the tooth height at both ends toward the axial center of the pinion gear that revolves backward and revolves with respect to the rotation direction of the differential case when the vehicle is traveling forward. The differential apparatus according to claim 1. A differential case that is rotationally driven by the driving force of the engine, a pair of output-side helical side gears, a first and second gear portions, and a first pinion gear that meshes with one of the helical side gears; 1 and a second gear portion, the first gear portion is composed of a helical pinion gear meshed with the other helical side gear, each second gear portion meshed with each other, and a differential case formed with each helical pinion gear. The helical pinion gear has a housing hole that is slidably and rotatably housed, and the helical pinion gear has a helical hole that contacts the housing hole when the helix angle increases due to the reaction force received by the first and second gear portions. in the axial direction central portion of the pinion gear that tooth height of the pinion gear is formed to be higher in succession from the tooth height of the end portions Differential device according to claim. Formed so that the tooth height of the pinion gear is continuously higher than the tooth height at both ends toward the axial center of the pinion gear that revolves backward and revolves with respect to the rotation direction of the differential case when the vehicle travels forward. The differential device according to claim 3.

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