JPH0771563A - Differential gear - Google Patents

Abstract

PURPOSE:To flatten the torque characteristic of a clutch, and to accurately control the differential limiting force, in an electromagnetic clutch for limiting differential motion, by providing an eccentric groove to the clutch plate on one side, and by making the clutch plate on the other side flat, and also by specifying the surface roughness of both the clutch plates. CONSTITUTION:A multiple disk electromagnetic clutch for limiting the differential motion of the differential mechanism of a differential gear is made up of an outer plate 75 and an inner plate 77, and the outer plate 75 is connected to the internal gear by a spline 79, and the inner plate 77 is connected to the cam ring by a spline 81. In this case, the outer plate 75 is formed into a flat shape, while the inner plate 77 is provided with an eccentric groove 113. The flatness of the respective plates 75, 77 is made to be 0.15mum or less, and the surface roughness thereof is made to be 5mum or more, and also the surfaces of the respective plates 75, 77 are subjected to carburizing hardening. Thereby, the oil retaining quantity between the plates 75 and 77 is reduced, and also the magnetic resistance is reduced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vehicle differential device.

[0002]

2. Description of the Related Art A differential device 201 as shown in FIG. 7 is disclosed in Japanese Laid-Open Utility Model Publication No. Hei 4-84958. This includes a differential mechanism 203, a multi-plate type main clutch 205 and a pilot clutch 207, an electromagnet 211 that attracts the armature 209 and fastens the pilot clutch 207, and a ball cam 213. When the pilot clutch 207 is engaged, the differential torque of the differential mechanism 203 is applied to the ball cam 213, the cam thrust force engages the main clutch 205, and the coupling force between the clutches 205 and 207 limits the differential.

8 and 9 show the outer plate 215 and the inner plate 2 of the pilot clutch 207, respectively.
17, the magnetic flux 219 of the electromagnet 211 is guided to the armature 209 via the plate plates 215 and 217. The differential case 22 is attached to the pilot clutch 207.
Oil is supplied from the opening 223 of each plate 21
Lubricate the sliding surfaces of 5, 217. The outer plate 215 is provided with a radial groove 225 as shown in FIG. 8, and the inner plate 217 is centered on the clutch plate 21 as shown in FIG.
An arc-shaped eccentric groove 227, which is eccentric from the center of 7, is provided. The grooves 225 and 227 hold the oil and supply it to the sliding surface.

[0004]

As described above, since the grooves 225 and 227 are formed in both the plates 215 and 217 and the oil is retained, the magnetic resistance of the pilot clutch 207 is large. The influence of this magnetic resistance is the electromagnet 211.
The larger the magnetic force (exciting current) of, the stronger it appears, and the differential limiting force decreases. Also, the grooves 225, 2 of each plate 215, 217
The friction coefficient μ decreases due to the wedge effect in which oil is guided to the sliding surface from the wedge-shaped space formed between 27 and the sliding surface, and the surface roughness of each plate 215, 217 is 3-11.
It is smoothed in the μm range and μ is small. At high differential rotation, μ is halved due to the strong influence of this wedge effect.
Due to such magnetic resistance and μ change, the differential limiting characteristic changes intricately and a flat characteristic cannot be obtained, which makes precise control of the differential limiting force difficult.

Therefore, an object of the present invention is to provide a differential device in which the variation of the differential limiting characteristic is small and the differential limiting force can be precisely controlled.

[0006]

A differential device according to the present invention comprises a differential mechanism and an electromagnetic multi-plate clutch for limiting the differential, and the multi-plate clutch is a one-sided clutch plate provided with an eccentric groove. And the other clutch plate that is flat without grooves, and the surface of each clutch plate has a flatness of 0.15 μm.
And the surface roughness is 5 μm or more.

[0007]

Unlike the conventional example, the groove of one clutch plate of the multi-plate clutch is eliminated and made flat, so that fluctuations in magnetic resistance and μ decrease due to the wedge effect are reduced. Further, the surface roughness of each clutch plate is set to 5 μm or more to make it rough. By these measures, the differential limiting characteristic of the multi-plate clutch is suppressed from being changed and becomes flat, and the differential limiting force can be precisely controlled.

Further, since the eccentric groove provided on the one-side clutch plate can ensure wear durability and can hold a minimum amount of oil, fluctuations in magnetic resistance and decrease in μ can be further reduced.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT An embodiment will be described with reference to FIGS. FIG. 1 shows the differential device of this embodiment,
FIG. 6 shows a power system of a vehicle using this differential device. The left and right directions indicate the left and right directions in this vehicle and FIG. In addition, members and the like without reference numerals are not shown.

As shown in FIG. 6, this power system includes an engine 1, a transmission 3, a propeller shaft 5, a rear differential 7 (a differential device of the embodiment arranged on the rear wheel side), rear axles 9 and 11, and left and right rear axles. It is composed of wheels 13 and 15, left and right front wheels 17 and 19, and the like. Rear differential 7
The differential case 21 is rotatably arranged in the differential carrier 23, and the ring gear 25 is fixed to the differential case 21. The ring gear 25 meshes with the drive pinion gear 27, and the drive pinion gear 27 is connected to the propeller shaft 5 side with the drive pinion shaft 29.
It is formed integrally with.

Thus, the driving force of the engine 1 rotationally drives the differential case 21 via the transmission 3 and the propeller shaft 5. An oil sump is formed inside the differential carrier 23.

As shown in FIG. 1, left and right hubs 31 and 33 are arranged inside the differential case 21.
Reference numeral 33 is splined to the left and right rear axles 9 and 11, respectively.

A double pinion planetary gear type differential mechanism 35 is arranged in the differential case 21. The internal gear 37 is formed on the differential case 21, and the sun gear 39 is formed on the left hub 31. The outer and inner pinion gears 41 and 43 have left and right pinion carriers 51 and 53 via shafts 45 and 47 at both ends via bushes 49.
Is supported by. The pinion carriers 51 and 53 are integrated by welding, and the right pinion carrier 53 is integrally formed with the hub 33.

The driving force of the engine 1 is transmitted from the differential case 21 (internal gear 37) through the pinion gears 41 and 43 to the sun gear 39 (hub 31) and the pinion carrier 53.
(Hub 33) and sent to the left and right rear wheels 13, 15. When a difference in driving resistance occurs between the rear wheels, the driving force of the engine 1 is differentially distributed to the left and right sides by the rotation and revolution of the pinion gears 41 and 43.

A multi-plate type main clutch 57 is arranged between the cylindrical portion 55 of the pinion carrier 51 and the sun gear 39. On the left side of the main clutch 57, a washer 63 having a pawl 59 engaged with a lubricating hole 61 of the differential case 21 is arranged.

A cam ring 65 is arranged on the outer periphery of the hub 33, and a ball cam 67 is provided between the cam ring 65 and the pinion carrier 53. A needle bearing 69 and a washer 71 that receive the cam reaction force of the ball cam 67 are arranged between the cam ring 65 and the differential case 21.

A multi-plate type pilot clutch 73 (electromagnetic multi-plate clutch) is arranged between the differential case 21 and the cam ring 65. The pilot clutch 73 is shown in FIG.
And an inner plate 77 (one side clutch plate) shown in FIG. 3 and FIG. 3, respectively. The outer plate 75 is connected to the internal gear 37 by a spline 79, and the inner plate 77 is a spline 81. Is connected to the spline 83 of the cam ring 65. An armature 85 is arranged on the left side of the pilot clutch 73, and is positioned by a retaining ring 87. A ring-shaped electromagnet 93 is supported by the right boss portion 89 of the differential case 21 via bearings 91, 91 and is prevented from rotating toward the differential carrier 23 side. On the right side wall 95 of the differential case 21, a stainless steel ring 99 that prevents the magnetic flux 97 from being short-circuited and is guided to the armature 85 is arranged. As shown in FIGS. 2 and 3, each plate 75, 77
Are provided with voids 101 and 103 for preventing a short circuit of magnetic flux.

When the electromagnet 93 attracts the armature 85, the pilot clutch 73 is engaged and the differential torque of the differential mechanism 35 is applied to the ball cam 67, and the generated cam thrust force presses the main clutch 57 via the pinion carriers 51 and 53. The differential force is limited by the coupling force of the clutches 57 and 73.

The pilot clutch 73 is driven by the electromagnet 93.
The vehicle can make smooth and stable turns by adjusting slippage and loosening the differential limiting force appropriately. Further, if the differential limiting force is increased or the differential is locked, the straight running stability of the vehicle is improved, and even if one of the rear wheels idles on a bad road, a large driving force is applied to the other side due to the differential limiting force. It is sent to the wheel and the rough road running performance is improved. When the pilot clutch 73 is released, the cam thrust force of the ball cam 67 disappears and the main clutch 57
Is also released and the differential becomes free.

Lubrication holes 61 provided in the differential case 21,
Oil in the oil reservoir flows in and out from 107, 109, and 111, and lubricates the clutches 57 and 73, the differential mechanism 35, and the like.

As shown in FIG. 2, the outer plate 75 is flat and has no groove. Further, as shown in FIG. 3, the inner plate 77 is provided with an eccentric groove 113. Each plate 75, 77 has a flatness of 0.15 μm or less and a surface roughness of 5 μm or more. The surfaces of the plates 75 and 77 are carburized and quenched.

As described above, unlike the conventional example, since the groove is provided only in the inner plate 77, the plate 75,
The amount of oil retained between 77 is small and the magnetic resistance is small. Therefore, the engaging force (differential limiting force) of the pilot clutch 73 with respect to the exciting current of the electromagnet 93 is large, and the variation of the differential limiting characteristic with respect to the change of the exciting current is small. Further, since the number of grooves is small, the wedge effect is also reduced, and the variation of the friction coefficient μ between the plates 75 and 77 due to the change in the differential rotation speed can be suppressed to be small. Since the eccentric groove 113 has a good oil retaining property against centrifugal force, the plates 75 and 77 can be sufficiently lubricated. FIG. 4 and FIG. 5 are graphs showing these things by experiments. Here, in the combination A, the outer plate 215 is provided with the radial groove 225, and the inner plate 2
17 is a combination of the pilot clutch 207 of FIG. 7 in which an eccentric groove 227 is provided, and a combination B is a plate 75,
77 is a combination of the pilot clutches 73 of the embodiment. The flatness is 0.15 μm or less for both the combinations A and B, and the surface roughness is 3 to 11 for the combination A as described above.
On the other hand, in the case of the combination B, it is coarser than 5 μm while it is μm.

In the experiment shown in FIG. 4, the differential rotation speed was 20 rpm.
And the change of the clutch torque when the exciting current A of the electromagnet is changed while maintaining at 300 rpm.
The □ mark and the X mark are the graphs 115 and 117 of the combination A at 20 rpm and 300 rpm, respectively, and the ◇ mark and the Δ mark are 20 respectively.
Graphs 119 and 12 for combination B at rpm and 300 rpm
It is 1.

When the current value is 4.0 amperes and the graphs 115 and 119 under the same conditions are compared with each other, 3%, graph 1
Comparing No. 17 and 121, 58% is obtained, which means that the combination B of the embodiment in which the outer plate 75 is flat produces a larger torque than the combination A of the conventional example. This difference is due to the fact that the number of grooves is reduced and the wedge effect is suppressed to reduce the decrease of μ, and the reduction of the number of grooves facilitates the addition of magnetism.

3% difference at 20 rpm is 58 at 300 rpm
%, It can be seen that, as the differential rotation speed becomes higher, the torque decrease becomes more remarkable in the conventional example, while the flat characteristics are obtained in the embodiment. It appears in the difference between 20 rpm and 300 rpm in A and B (comparison of difference 123 between graphs 115 and 117 and difference 125 between graphs 119 and 121).

In the experiment shown in FIG. 5, the plates of the same combination A and B as in FIG. 4 were rubbed, the change of μ with respect to the rubbing time was obtained, and the effect of the groove combination on the wear was tested. The rubbing was performed by applying the oil described in FIG. 5 at 80 ° C. and applying a force of 200 kg-f to the plate at a differential rotation speed of 50 rpm. The graph 127 marked with ▲ is the combination A, and the graph 129 marked with ● is the combination B. In both graphs, μ converges to a constant value when the rubbing time exceeds 20 hours. It can be seen that in the combination B in which the eccentric groove is flat, the decrease in μ due to the wedge effect is suppressed to be small, and in the combination A, μ is greatly decreased due to the effect of the wedge effect due to the radial groove. In addition, for example, the inner plate 77
The surface treatment of CrN (chromium nitride) or the like can further reduce the decrease in μ.

As described above, in the combination B, since the change of μ and the magnetic resistance are small, the pilot clutch 73 can suppress the decrease of μ at the time of low surface pressure and high differential rotation to 10% or less, and the difference of the rear differential 7 can be reduced. The motion restriction force can be controlled precisely.
Further, since the decrease in μ is small, stick slip is prevented, and abrupt changes in the differential limiting force are prevented. For this reason, the steerability of the vehicle shown in FIG. 6 is significantly improved.

The groove of the inner plate 77 is replaced with the eccentric groove 113.
Due to this, the oil is better retained against centrifugal force than the radial groove. Therefore, it is possible to reduce the number of grooves while sufficiently performing the lubrication between the plates 75 and 77, and it is possible to further reduce the wedge effect and the magnetic resistance, which is advantageous.

[0029]

According to the differential device of the present invention, in the electromagnetic multi-disc clutch for limiting the differential, the eccentric groove is provided on the clutch plate on one side, the clutch plate on the other side is made flat, and the surface roughness of both clutch plates is increased. Was roughened to 5 μm or more. Therefore, the μ decrease due to the wedge effect and the magnetic resistance due to the oil in the groove are suppressed to be small, the characteristic of the clutch torque becomes flat, and the differential limiting force can be controlled more precisely.

[Brief description of drawings]

FIG. 1 is a sectional view of an embodiment.

FIG. 2 is a plan view of an outer plate used in an example.

FIG. 3 is a plan view of an inner plate used in an example.

FIG. 4 is a graph comparing a torque change with an exciting current between a conventional example and an example.

FIG. 5 is a graph comparing a change in friction coefficient due to friction between plates in a conventional example and an example.

FIG. 6 is a skeleton mechanism diagram showing a power system of a vehicle using the embodiment.

FIG. 7 is a sectional view of a conventional example.

FIG. 8 is a plan view of an outer plate used in a conventional example.

FIG. 9 is a plan view of an inner plate used in a conventional example.

[Explanation of symbols]

 7 Rear differential (differential measure) 35 Differential mechanism 73 Pilot clutch (electromagnetic multi-plate clutch) 75 Outer plate (other side clutch plate) 77 Inner plate (one side clutch plate) 113 Eccentric groove

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[Procedure amendment]

[Submission date] August 5, 1993

[Procedure Amendment 1]

[Document name to be amended] Statement

[Name of item to be amended] Claims

[Correction method] Change

[Correction content]

[Claims]

[Procedure Amendment 2]

[Document name to be amended] Statement

[Correction target item name] 0006

[Correction method] Change

[Correction content]

The differential device of the present invention comprises a differential mechanism and an electromagnetic multi-plate clutch for limiting the differential, and the multi-plate clutch is flat with one side clutch plate provided with an eccentric groove and no groove. The other side clutch plate is provided, and the surface of each clutch plate has a flatness of 0.15 mm or less and a surface roughness of 5 μm or more.

[Procedure 3]

[Document name to be amended] Statement

[Correction target item name] 0021

[Correction method] Change

[Correction content]

As shown in FIG. 2, the outer plate 75 is flat and has no groove. Further, as shown in FIG. 3, the inner plate 77 is provided with an eccentric groove 113. Each plate 75, 77 has a flatness of 0.15 mm or less and a surface roughness of 5 μm or more. The surfaces of the plates 75 and 77 are carburized and quenched.

[Procedure amendment 4]

[Document name to be amended] Statement

[Name of item to be corrected] 0022

[Correction method] Change

[Correction content]

As described above, unlike the conventional example, since the groove is provided only in the inner plate 77, the plate 75,
The amount of oil retained between 77 is small and the magnetic resistance is small. Therefore, the engaging force (differential limiting force) of the pilot clutch 73 with respect to the exciting current of the electromagnet 93 is large, and the variation of the differential limiting characteristic with respect to the change of the exciting current is small. Further, since the number of grooves is small, the wedge effect is also reduced, and the variation of the friction coefficient μ between the plates 75 and 77 due to the change in the differential rotation speed can be suppressed to be small. Since the eccentric groove 113 has a good oil retaining property against centrifugal force, the plates 75 and 77 can be sufficiently lubricated. FIG. 4 and FIG. 5 are graphs showing these things by experiments. Here, in the combination A, the outer plate 215 is provided with the radial groove 225, and the inner plate 2
17 is a combination of the pilot clutch 207 of FIG. 7 in which an eccentric groove 227 is provided, and a combination B is a plate 75,
77 is a combination of the pilot clutches 73 of the embodiment. The flatness is 0.15 mm or less for both the combinations A and B, and the surface roughness is 3 to 11 for the combination A as described above.
On the other hand, in the case of the combination B, it is coarser than 5 μm while it is μm.

Claims (1)

[Claims] 1. A differential mechanism and an electromagnetic multi-disc clutch for limiting the differential, wherein the multi-disc clutch includes one side clutch plate provided with an eccentric groove and another side clutch plate flat without a groove. The surface of each clutch plate has a flatness of 0.15μ.
A differential device having a surface roughness of 5 m or less and a surface roughness of 5 μm or more.