JPH09242846A - Differential gear - Google Patents

Abstract

PROBLEM TO BE SOLVED: To miniaturize a differential device having torque amplifying action and to make it lighter. SOLUTION: The rotating power of a propeller shaft 12 is distributed to the first drive pinion 30 and a cylindrical part 36 by a differential mechanism 18, and the power of the first drive pinion 30 is speed-reduced by the first speed reducing mechanism 34, namely amplifying its torque, and transmitted to a right axle, and on the other hand, the power of the cylindrical part 36 is transmitted to the second drive pinion 42 through a counter drive gear 38 and a counter driven gear 40, and further speed-reduced by the second speed reducing mechanism 46, namely amplifying its torque, and transmitted to a left axle 16.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a differential gear, and more particularly to a technique for forming a differential gear having a torque amplifying function in a small size and a compact size.

[0002]

2. Description of the Related Art Rotational power of a single input member can be decelerated to a pair of a first output member and a second output member via a bevel gear type or planetary gear type differential mechanism, that is, relative to each other. A differential device that transmits rotatably is used in a final reduction gear device that distributes power to the left and right drive wheels of an automobile.
The device described in JP-A-4-230424 is an example of such a device, and a drive pinion having a small diameter provided on a propeller shaft (input member) to a drive pinion having a large diameter fixed to a differential case of a bevel gear type differential mechanism is used. By transmitting power to the ring gear, the speed is reduced and the power is distributed to the left and right axles (output members) via the differential mechanism. By decelerating and rotating the pair of output members with respect to the input member, a decrease in torque due to power distribution is suppressed, or the output member is rotated with a torque larger than that of the input member.

FIG. 4 shows an example of a differential gear used in such a conventional automobile final reduction gear transmission.
The rotational power is transmitted to the differential case 108 of the bevel gear type differential mechanism 106 via a small-diameter drive pinion (input member) 102 and a large-diameter ring gear 104, which are connected to a propeller shaft (not shown), and the pinion shaft 0 is connected to the pinion shaft 110. A plurality of pinion gears 11 rotatably arranged in the
Power is distributed from 2 to the left and right axles (output members) 118 and 120 via a pair of side gears 114 and 116. The pair of axles 118, 120 and the differential mechanism 106 are rotatably arranged around a straight line L located in a plane perpendicular to the rotation center line S of the drive pinion 102. Further, the drive pinion 102 and the ring gear 104 are spiral bevel gears or hypoid gears, and a thrust force in the direction of the rotation center line S acts on the drive pinion 102 due to the influence of the twisting of the meshing teeth and the pressure angle, while the diff case 108 The thrust force in the straight L direction acts on the drive pinion 10
2 and the differential case 108 via the pair of tapered roller bearer 122 and 124, respectively.
It is held by 26 so as to be immovable and rotatable in the axial direction. The ring gear 104 is fixed to the differential case 108 by a plurality of bolts 128.

[0004]

However, in such a conventional differential device, deceleration, that is, torque amplification is performed when power is transmitted from the input member to the differential mechanism.
Large torque is applied to each member of the differential mechanism,
It was necessary to adopt a large (large diameter) differential mechanism. The differential device 100 shown in FIG. 4 will be described in detail. As shown in the skeleton diagram of FIG. 5, the torque of the drive pinion 102 is T _P , the ring gear 104 and the drive pinion 102.
Assuming that the gear ratio between and is if, the torque transmitted to the differential mechanism 106 is T _P × if, and the torque transmitted to both axles 118, 120 is T _P × if / 2.

The present invention has been made in view of the above circumstances, and it is an object of the present invention to reduce the size and weight of a differential device having a torque amplifying function.

[0006]

SUMMARY OF THE INVENTION To achieve the above object, the present invention arranges the rotational power of a single input member in a straight line in a plane substantially perpendicular to the center line of rotation of the input member. A differential device for decelerating and transmitting differentially to a pair of the first output member and the second output member, which are: (a) the rotational power of the input member is coaxial with the rotation center line of the input member. A differential mechanism that differentially transmits to a pair of a first intermediate rotating member and a second intermediate rotating member disposed above, (b) the first intermediate rotating member
A first pinion gear provided on the intermediate rotating member so as not to rotate relative to it;
And a first reduction gear mechanism comprising a first large gear having a diameter larger than that of the first small gear and provided on the first output member so as to be relatively non-rotatable and meshed with the first small gear; Two
A third intermediate rotating member arranged substantially parallel to the intermediate rotating member and spaced apart in a direction substantially parallel to the straight line; and (d) transmitting rotational power of the second intermediate rotating member to the third intermediate rotating member. (E) a second pinion gear that is non-rotatably provided on the third intermediate rotating member, and (e) is non-rotatably provided on the second output member and in the same direction as the first gear wheel. A second reduction gear composed of a second large gear having a diameter larger than that of the second small gear and meshed with the second small gear so as to rotate to.

[0007]

In such a differential device, after the power is distributed to the first intermediate rotating member and the second intermediate rotating member by the differential mechanism, the speed is reduced by the first speed reducing mechanism and the second speed reducing mechanism, that is, the torque is reduced. Since the power is amplified and transmitted to the first output member and the second output member, it is not necessary to apply a large torque to the differential mechanism, and the torque acting on the large gear of the reduction mechanism is also output as a pair. It is the same as the torque acting on the members, and the mechanical strength required for each part is reduced, so that a small differential mechanism or reduction mechanism can be adopted. The first intermediate rotating member and the second intermediate rotating member are arranged coaxially with the rotation center line of the input member, and the second output member is arranged substantially parallel to the first intermediate rotating member. Since the power is transmitted through the intermediate rotating member, the small differential mechanism and the reduction gear mechanism can be adopted, and the entire differential device can be made small and lightweight.

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION A preferred embodiment of the present invention will be described. (Embodiment 1) The speed reduction ratio from the second intermediate rotation member to the second output member and the speed reduction ratio from the first intermediate rotation member to the second output member are equal to each other. The gear ratio of the power transmission path is set.
In this case, if the differential mechanism has no differential, the first output member and the second output member can be rotated at a constant speed,
It is preferably applied to final reduction gears of automobiles. However, it is also possible to apply it to other than the final reduction gear of the automobile.

(Second Embodiment) In the first embodiment, the power transmission means transmits the rotational power of the second intermediate rotating member to the third intermediate rotating member at the same rotational speed but in opposite rotational directions. In the gear train, the second pinion gear has the same diameter dimension as the first pinion gear, and the second gear wheel is the first pinion.
It has the same diameter as the large gear. A chain or the like can be used as the power transmission means.

(Third Embodiment) The differential mechanism is of a bevel gear type, and differentially transmits power to a pair of side gears via a pinion gear by rotating a differential case integrally with the input member. . However, in implementing the present invention, it is possible to employ a planetary gear type differential mechanism.

(Embodiment 4) In Embodiment 2, the counter gear train is provided in each of the second intermediate rotating member and the third intermediate rotating member, and a pair of counters meshed with each other with the same diameter dimension. A drive gear and a counter driven gear. This is the simplest gear train, and the differential gear is configured to be small and lightweight, but it is also possible to employ a gear train using three or more gears when implementing the present invention.

(Embodiment 5) The first large gear and the second gear
The large gears are arranged so that they can rotate relative to each other, and
The thrust forces associated with the meshing of the small gear and the second small gear are brought into contact with each other, and the thrust forces are canceled by the contact. In this case, it is not always necessary to use the tapered roller bearing 122 or 124 described in the conventional device of FIG. 4 as a bearing for rotatably supporting the first large gear and the second large gear. In addition to using inexpensive ball bearings, a predetermined differential limiting force can be generated by appropriately setting the friction coefficient μ on the back surface or by interposing a friction plate having an appropriate friction coefficient μ. it can.

(Embodiment 6) In the above Embodiment 5,
An annular groove is formed around the straight line on the back surfaces of the first large gear and the second large gear that face each other, and a ring-shaped collar is provided across both of them. In this case, the first
The large gear and the second large gear are centered by the collar, and their postures are maintained coaxially with the straight line, and twisting due to the thrust force is prevented. When a gap is created between the first large gear and the second large gear due to the presence of this collar, a predetermined differential limiting force can be obtained by the friction coefficient μ of the collar.

(Embodiment 7) In Embodiment 4, the first intermediate rotation member and the second intermediate rotation member are axially immovable relative to each other via the differential mechanism, and are arranged on the first intermediate rotation member. The first small gear provided and the counter drive gear provided in the second intermediate rotating member have meshing teeth twisted in opposite directions to cancel the thrust force associated with meshing. In this case, it is not always necessary to use the tapered roller bearings 122 and 124 described in the conventional apparatus of FIG. 4 as a bearing for rotatably supporting a differential case of a differential mechanism to which rotational power is transmitted from an input member. It is not necessary, and inexpensive ball bearings can be used.

Incidentally, the first small gear and the first large gear,
A bevel gear or a hypoid gear is preferably used as the second small gear and the second large gear.

Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is an example of a case where a differential gear according to an embodiment of the present invention is used in an automobile final reduction gear, and the differential gear 10 outputs rotational power of a propeller shaft 12 as an input member, The propeller shaft 12 is decelerated and differentially transmitted to a pair of right and left axles 14 and 16 arranged on a straight line L located in a plane orthogonal to the first centerline S1 which is the rotation centerline of the propeller shaft 12. It is a thing. In the present embodiment, the first center line S1 and the straight line L are located in one plane (paper surface of FIG. 1) and are orthogonal to each other. The differential case 20 of the bevel gear type differential mechanism 18, which is rotatably arranged around the first center line S1, is connected to the propeller shaft 12 by spline fitting or the like so as not to be rotatable relative to each other, so that the differential case 20 can be integrally rotated. Power is distributed from the plurality of pinion gears 24 rotatably attached to the pinion shaft 22 arranged in the differential case 20 so as to be orthogonal to the first center line S1 to the pair of side gears 26, 28.

The side gear 26 has a shaft portion 30 of a first drive pinion 30 arranged coaxially with the first center line S1.
a is connected by a spline fitting or the like so that it cannot rotate relatively, and by a snap ring or the like, it does not move relatively in the axial direction. The first drive pinion 30 is used in the differential case 2
Spiral bevel gear 3 with a small diameter at the tip protruding from 0
0b, and is meshed with a first ring gear 32 which is attached to the right axle 14 by spline fitting or the like so as not to be relatively rotatable. The first ring gear 32 has a diameter larger than that of the spiral bevel gear 30b, and is decelerated and rotated at a predetermined reduction ratio. The first drive pinion 30 is a first intermediate rotating member, the spiral bevel gear 30b thereof corresponds to a first small gear, the first ring gear 32 corresponds to a first large gear, and the spiral bevel gears 30b and 30 The ring gear 32 constitutes a first reduction mechanism 34. The right axle 14 corresponds to the first output member.

The side gear 28 is relatively rotatably fitted to the outer peripheral side of the shaft portion 30a of the first drive pinion 30, and a counter drive gear 38 is splined on the cylindrical portion 36 protruding from the differential case 20 to the outside. They are arranged so that they cannot rotate relative to each other by fitting or the like and cannot move relative to each other in the axial direction by a snap ring or the like. The counter drive gear 38 is meshed with a counter driven gear 40 that is rotatably arranged around a second center line S2 that is parallel to the first center line S1, and the counter driven gear 40 moves around the second center line S2. It is attached to a shaft portion 42a of the second drive pinion 42 that is rotatably disposed so as not to be relatively rotatable by spline fitting or the like and to be relatively immovable in the axial direction by a snap ring or the like. Counter drive gear 38 and counter driven gear 4
0 is composed of helical gears with the same diameter,
The second drive pinion 42 is rotated at the same rotational speed in the opposite direction with respect to the side gear 28. These counter drive gear 38 and counter driven gear 40 correspond to power transmission means in the counter gear train, the cylindrical portion 36 corresponds to a second intermediate rotating member, and the second drive pinion 42.
Corresponds to the third intermediate rotating member. The second center line S2 is set parallel to the first center line S1 in a direction substantially parallel to the straight line L, specifically, to the left in FIG. The center line S1, the second center line S2, and the straight line L are located in the same plane. The meshing teeth of the counter drive gear 38 are inclined in the direction opposite to the twisting direction of the meshing teeth of the spiral bevel gear 30b.

The second drive pinion 42 has a spiral bevel gear 42b of the same size as that of the spiral bevel gear 30b at its tip, and is attached to the left axle 16 by spline fitting or the like so as not to rotate relative to each other. It is meshed with the second ring gear 44. The second ring gear 44 has the same diameter as the first ring gear 32, and is meshed with the spiral bevel gear 42b so as to be rotated in the same direction as the first ring gear 32. Specifically, the first ring gear 32 and the second ring gear 44 are relatively rotatably arranged so as to be back-to-back at the center between the first center line S1 and the second center line S2. It is rotated in the same direction by being meshed with the drive pinions 30 and 42 having the opposite rotation directions on the outer side. Further, both ring gears 32 and 44 are brought into contact with each other by the thrust force that is applied along with the engagement with the bevel gears 30b and 42b. On the back surfaces of the first ring gear 32 and the second ring gear 44, annular grooves centering on the straight line L are formed, respectively, and the ring-shaped collar 48 spans both of them.
Are provided and are brought into contact with each other via the collar 48. The spiral bevel gear 42b corresponds to a second small gear, the second ring gear 44 corresponds to a second large gear, and the spiral bevel gear 42b and the second ring gear 44 constitute a second reduction mechanism 46. The left axle 16 corresponds to the second output member.

In such a differential device 10, the rotational power of the propeller shaft 12 is distributed to the first drive pinion 30 and the cylindrical portion 36 by the differential mechanism 18.
The power of the first drive pinion 30 is decelerated by the first reduction mechanism 34, that is, the torque is amplified and transmitted to the right axle 14, while the power of the cylindrical portion 36 is transmitted to the second drive via the counter drive gear 38 and the counter driven gear 40. The second reduction mechanism 46 is transmitted to the pinion 42.
Is decelerated, that is, the torque is amplified and transmitted to the left axle 16. In that case, the diameter dimensions of the counter drive gear 38 and the counter driven gear 40 are the same, and
Since the reduction gear ratios of the reduction gear mechanism 34 and the second reduction gear mechanism 46 are the same, if there is no differential in the differential mechanism 18, both axles 14,
16 is rotated at a constant speed in the same direction.

Here, the differential device 10 is a differential mechanism 1.
Since the power is distributed by 8 and the torque is amplified by the reduction mechanisms 34 and 46, the differential mechanism 1
A large torque is not applied to the ring gear 8 and the ring gears 32 and 44, the mechanical strength required for each part is reduced, and a small differential mechanism 18 and reduction gear mechanisms 34 and 46 can be adopted. That is, when the torque of the propeller shaft 12 is T _P as shown in the skeleton view of FIG.
The torque acting on T remains at T _P , the torques of the first drive pinion 30 and the second drive pinion 42 are T _P / 2, respectively, and the gear ratio between the ring gears 32, 44 and the drive pinions 30, 42 is set to if. Then, the torque transmitted to both axles 14 and 16 becomes (T _P / 2) × if = T _P × if / 2 as in the conventional device of FIG. 5, but the differential mechanism 18 simply includes the propeller shaft 12 Since only the torque T _P of
If, and the torque acting on the ring gears 32 and 44 is T _P × if / 2, which is 1/2 that of the conventional device. Since the gear ratio if is usually about 2.0 to 6.0,
In particular, the differential mechanism 18 can be significantly downsized.

The first drive pinion 30 and the second drive pinion 42 are arranged parallel to each other, and
Since power is transmitted to the drive pinion 42 via a pair of counter drive gear 38 and counter driven gear 40, the small differential mechanism 18,
Coupled with the fact that the speed reducing mechanisms 34 and 46 can be adopted, the differential device 10 as a whole is made compact and lightweight.

Incidentally, in the case where the same degree of torque transmission is performed while ensuring the same degree of strength as in the conventional case, the width dimension which is the dimension in the left-right direction and the length dimension which is the dimension in the up-down direction in FIG.
The total weight is 5% compared to the conventional device in FIG.
It was possible to reduce by about 16%, by about 30%.

Further, in this embodiment, the first ring gear 32 and the second ring gear 44 are arranged back to back, and the thrust force acting upon meshing with the spiral bevel gears 30b, 42b is applied via the collar 48 via the collar 48. Since they are brought into contact with each other, the contact force cancels the thrust force. The arrow a in FIG. 2 represents the thrust force acting on both ring gears 32 and 44. As a result, the ball bearing 52 can be adopted as the bearing means for rotatably disposing the ring gears 32 and 44 on the carrier 50, and the tapered roller bearing is used as in the conventional device of FIG. It is cheaper than the case. In FIG. 2, the hatching of the cross-sectional portion of each portion is omitted in order to clearly show the thrust force a.

Both ring gears 32 and 44 are collar 4
8 is centered and its posture is straight line L
Since it is held coaxially with, the twisting due to the thrust force is prevented. Collar 48 is both ring gears 32, 4
4 is slidably contactable with respect to 4 but collar 4
8 can be set appropriately or the appropriate friction coefficient μ
A predetermined differential limiting force can be generated by interposing the friction plate.

The first drive pinion 30 and the cylindrical portion 36 are not allowed to move relative to each other in the axial direction via the differential case 20, and the spiral bevel gear 30b and the cylindrical portion 36 of the first drive pinion 30 are fixed to each other. Since the meshing teeth of the provided counter drive gear 38 are twisted in the opposite directions, the thrust forces acting upon meshing with the first ring gear 32 and the counter driven gear 40 cancel each other out. The arrow b in FIG. 2 represents the thrust force that acts on the spiral bevel gear 30 b and the counter drive gear 38. Accordingly, the ball bearings 54, 5 serve as bearing means for rotatably disposing the differential case 20 and the first drive pinion 30 on the carrier 50.
6 can be adopted, which is less expensive than the case where a tapered roller bearing is used as in the conventional device of FIG.

The second drive pinion 42 is rotatably held by the carrier 50 by a pair of tapered roller bearings 58.

The differential case 20 of the differential mechanism 18 is held by the carrier 50 via a ball bearing 54,
Since the propeller shaft 12 is connected to the differential case 20 by spline fitting or the like so as not to rotate relative to each other, the bolt 128 for fixing the ring gear 104 as in the conventional device of FIG. 4 is not necessary.

While the embodiment of the present invention has been described in detail with reference to the drawings, the present invention can be embodied in other forms.

For example, in the above embodiment, the first ring gear 3
Although the second and second ring gears 44 are arranged so as to be back-to-back, it is also possible to dispose the second and second ring gears 44 to the outside of the drive pinions 30, 42 so that the meshing teeth face inward.

Further, in the above embodiment, the thrust force on the side of the first drive pinion 30 is offset, but the thrust force on the side of the second drive pinion 42 is offset, so that the direction of twist of the meshing teeth is changed. Can also be set.

Further, although the reduction mechanisms 34 and 46 of the above-mentioned embodiment are constructed by using bevel gears, it is also possible to use hypoid gears.

Although not specifically exemplified, the present invention can be embodied with various modifications and improvements based on the knowledge of those skilled in the art.

[Brief description of drawings]

FIG. 1 is a cross-sectional view of a differential gear that is an embodiment of the present invention.

FIG. 2 is a diagram illustrating that thrust forces generated by meshing gears cancel each other out in the differential device of FIG.

FIG. 3 is a diagram for explaining the transmission torque of each part during torque transmission in the differential device of FIG.

FIG. 4 is a cross-sectional view showing an example of a conventional differential device.

5A and 5B are diagrams illustrating transmission torques of respective parts during torque transmission in the differential device of FIG.

[Explanation of symbols]

 10: Differential device 12: Propeller shaft (input member) 14: Right axle (first output member) 16: Left axle (second output member) 18: Differential mechanism 30: First drive pinion (first intermediate rotating member) ) 30b: spiral bevel gear (first small gear) 32: first ring gear (first large gear) 34: first reduction mechanism 36: cylindrical portion (second intermediate rotating member) 38: counter drive gear (power transmission means) ) 40: Counter driven gear (power transmission means) 42: Second drive pinion (third intermediate rotating member) 42b: Spiral bevel gear (second small gear) 44: Second ring gear (second large gear) 46: Second Reduction mechanism S1: First center line (rotation center line of input member) L: Straight line

Claims (1)

[Claims] 1. A deceleration of rotational power of a single input member to a pair of a first output member and a second output member arranged in a straight line in a plane substantially perpendicular to a rotation center line of the input member. A differential device that differentially transmits the input member, wherein a rotational power of the input member is provided coaxially with a rotation center line of the input member
A differential mechanism that differentially transmits to the intermediate rotating member, and a first non-rotatably provided on the first intermediate rotating member.
A pinion gear, and a first reduction gear mechanism that is non-rotatably provided on the first output member and meshes with the first pinion gear, and includes a first gear wheel having a larger diameter than the first pinion gear; 2 a third intermediate rotating member which is arranged substantially parallel to the intermediate rotating member and spaced apart in a direction substantially parallel to the straight line; and a power for transmitting the rotational power of the second intermediate rotating member to the third intermediate rotating member. A transmission means and a second non-rotatable second intermediate rotation member
A pinion gear and a second pinion having a diameter larger than that of the second pinion gear that is fixed to the second output member such that it cannot rotate relative to the first gear wheel and that meshes with the second pinion gear so as to rotate in the same direction as the first gear wheel. A second reduction gear mechanism comprising two large gears.