JPH04351329A - Electromagnetic clutch - Google Patents

Abstract

PURPOSE:To enhance the maneuvering response by reducing ill influence upon adjustment of the fastening force due to the residual magnetism of a magnetic circuit member such as an armature or a friction clutch. CONSTITUTION:An electromagnetic clutch according to the invention is equipped with a friction clutch 73, an electric magnet 79 to perform clutching motion by giving a magnetic force to an armature 25, and a non-magnetic substance which is installed between the armature and electric magnet 79 and which admits penetration of the magnetic force of the magnet 79 while shuts from the residual magnetism.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electromagnetic clutch used, for example, for limiting the differential of a differential device.

0002

2. Description of the Related Art Japanese Patent Application Laid-Open No. 195449/1983 describes a "slip limited differential gear assembly". This is a differential device that uses an electromagnetic clutch to limit differential movement. The multi-plate clutch portion of the electromagnetic clutch is housed in a rotating case together with the differential mechanism, and the electromagnet is fixed to a housing that houses the rotating case. The armature is arranged opposite to the electromagnet and is connected to a pressing member passing through the rotating case. In this way, when the armature is attracted by the electromagnet, the clutch is engaged via the pressing member, thereby limiting the differential.

0003

[Problems to be Solved by the Invention] However, the armature, pressing member, clutch plate, etc. are magnetized by the large magnetic force when the clutch is attracted, and this residual magnetism deteriorates the response of clutch release and makes it difficult to control the differential limiting force. Negative effects occur.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide an electromagnetic clutch in which the influence of residual magnetism on clutch operation response is slight.

[0005]

[Means for Solving the Problems] The electromagnetic clutch of the present invention includes a friction clutch, an electromagnet that applies magnetic force to the armature to operate the clutch, and an electromagnet that is arranged between the armature and the electromagnet so that the magnetic force of the electromagnet passes through but there is residual magnetism. is characterized in that it includes a non-magnetic material that blocks.

[0006]

[Operation] Even if a magnetic circuit member such as an armature or a clutch is magnetized, residual magnetism is blocked by the non-magnetic material placed between the armature and other members. Therefore, the adverse effect of residual magnetism on clutch torque (clamping force) is reduced, and the operational response of the clutch is improved.

[0007]

[Embodiment] One embodiment will be explained with reference to FIGS. 1 to 5.

FIG. 1 shows a differential device using this embodiment, and FIG. 5 shows a power system of a vehicle using this device. Hereinafter, the left and right directions are the left and right directions in this vehicle and in Figures 1 and 2, and the upper part in Figure 1 is the front of this vehicle (Figure 5
above). Furthermore, members not provided with reference numerals are not shown.

First, the configuration of the power system will be explained with reference to FIG.

This power system includes an engine 1, a transmission 3, a propeller shaft 5, a rear differential 7 (the differential device shown in FIG. 1 located on the rear wheel side), and rear axles 9, 1.
1. It is composed of left and right rear wheels 13, 15, left and right front wheels 17, 19, etc.

Next, the rear differential 7 will be explained.

The differential case 21 is supported within the differential carrier 23 via bearings 25, 25. As shown in FIG. 5, a ring gear 27 is fixed to the differential case 21, and the ring gear 27 meshes with a drive pinion gear 29. The drive pinion gear 29 is integrally formed at the rear end of a drive pinion shaft 31 connected to the propeller shaft 5 side. In this way, the rotation of the engine 1 rotates the differential case 21 from the transmission 3 via the propeller shaft 5.

Inside the differential case 21 are left and right hubs 33.
, 35 are arranged coaxially, the left hub 33 being splined to the left rear axle 9, and the right hub 35 being splined to the right rear axle 11.

Further, a planetary gear type differential mechanism 37 is arranged inside the differential case 21. That is,
An outer pinion gear 41 meshes with the internal gear 39, an inner pinion gear 43 meshes with this gear 41, and a sun gear 45 meshes with this gear 43.

Each pinion gear 41, 43 is rotatably supported on a respective pinion shaft 47, 49, and each shaft 47, 49 is connected to a left and right pinion carrier 51, 5.
3 is supported at both ends. The internal gear 39 is formed on the differential case 21, and the sun gear 45 is formed on the hub 33. The left and right pinion carriers 51, 53 are welded together. Further, the right carrier 53 forms a flange portion of the right hub 35.

In this way, the differential mechanism 37 is constructed, and the rotation of the differential case 21 (internal gear 39) is controlled by the sun gear 45 (hub 33) via the pinion gears 41, 43.
) and pinion carriers 51, 53 (hub 35), and the transmission is transmitted to the left and right rear wheels 13, 15 via the hubs 33, 35, and when a difference in drive resistance occurs between the rear wheels, each pinion gear 41 , 43 are differentially distributed to the left and right sides due to their rotation and revolution.

A multi-disc main clutch 55 connecting the left pinion carrier 51 and the left hub 33 is disposed on the left side of the differential mechanism 37.

The differential case 21 is provided with openings 57 and 59. The differential carrier 23 is filled with lubricating oil, and as the differential case 21 rotates, this lubricating oil flows in and out of the openings 57 and 59 to lubricate the inside of the differential case 21.

A cam ring 61 is arranged on the right side of the pinion carrier 53. As shown in FIG. 2, a ball cam 65 is formed between the pinion carrier 53 and the cam ring 61 with balls 63 interposed therebetween. Cam ring 6
1 and the right side wall 67 of the differential case 21, a needle bearing 69 and a washer 71 are arranged from the left.

Between the cam ring 61 and the differential case 21 is a multi-plate pilot clutch 73 (
A friction clutch) is installed. An armature 75 is arranged on the left side of the clutch 73, and is spline connected to the cam ring 61 at its inner periphery. As shown in an enlarged view in FIG. 3, a thin plate 77 made of resin (non-magnetic material) is arranged on the right side of the armature 75.

On the right side of the right side wall 67 is a ring-shaped electromagnet 7.
9 is placed. The electromagnet 79 includes an electromagnetic coil 81 and a yoke 83, is supported by the differential case 21 via a bearing 85, and is fixed to the differential carrier 23 via a support member. The lead wire 8 is connected to the electromagnetic coil 81.
Excitation current is supplied via 6. A non-magnetic ring 87 is embedded in the right side wall 67 to prevent the magnetic force of the electromagnet 79 from short-circuiting and guide it to the armature 75.

When the excitation current of the electromagnet 79 is turned ON, the armature 75 is attracted through the magnetic circuit 89, the pilot clutch 73 is pressed and engaged with the right side wall 67, and the cam ring 61 is connected to the differential case through the clutch 73. 2
1. On the other hand, since the cam ring 61 is connected to the pinion carrier 53 side via the cam 65, the differential rotation between the internal gear 39 and the pinion gears 41 and 43 is limited depending on the engagement force (slip) of the clutch 73. Then, the differential movement of the differential mechanism 37 is limited.

When the pilot clutch 73 is engaged, the differential torque of the differential mechanism 37 acts on the cam 65, producing left and right cam thrust forces 91 and 93, as shown in FIG. Pinion carrier 51 due to left thrust force 91
, 53 move to the left to press and engage the main clutch 55 between the carrier 51 and the differential case 21.

In this way, the engagement force of the main clutch 55 is added to the engagement force of the pilot clutch 73, and the differential limiting force of the differential mechanism 37 is strengthened. Note that the right thrust force 93 is input to the differential case 21 via the bearing 69 and the washer 71, and is canceled out by the left thrust force 91.

The pilot clutch 73 is operated by the electromagnet 79.
When the slippage is adjusted, the thrust force 91 changes accordingly, the engagement force of the main clutch 55 changes, and the differential limiting force of the differential mechanism 37 can be controlled. Each clutch 55, 7
If the fastening force of No. 3 is sufficiently large, the differential rotation between the rear wheels 13 and 15 will be locked, and if the fastening force is moderately relaxed, this differential rotation will be allowed. When the excitation current of the electromagnet 79 is turned off, the clutch 73 is released, the slide force 91 disappears, the clutch 55 is released, and the differential rotation becomes free.

The clutch plate 95 and armature 75 of the clutch 73 are magnetized by the magnetic force of the electromagnet 79 and become tinged with residual magnetism. The thin plate 77 disposed between the armature 75 and the clutch plate 95 transmits the magnetic force of the electromagnet 79, but its material and thickness are selected so as to substantially block such residual magnetism.

The graph in FIG. 4 shows the torque (clamping force) of the pilot clutch 73 with respect to the change in the excitation current of the electromagnet 79.
It shows change. Graph 97 shows the excitation current,
A solid line graph 99 shows the torque change in this embodiment in which the thin plate 77 is arranged. Further, a broken line graph 101 shows the torque change in a state in which the thin plate 77 is removed from the example.

In the conventional example, the armature 91 is
is attracted to the multi-disc clutch 73 side, so the excitation current is turned off.
Even at F, the torque of the clutch 73 is not released immediately, and as shown in graph 101, the torque falls slowly. On the other hand, in the embodiment, the residual magnetism between the armature 75 and the clutch plate 95 is cut off, so the excitation current is turned off.
When this is done, the armature 75 immediately disengages from the clutch plate 95, the torque falls quickly as shown in graph 99, and the response of clutch 73 opening to excitation current OFF is good. Such an effect can be obtained not only when the clutch 73 is released, but also when the engagement force is loosened, so that the response is improved in all directions in which the differential limiting force is loosened.

The adjustment of the differential limiting force by the electromagnet 79 can be operated manually from the driver's seat or automatically in accordance with road surface conditions, vehicle steering conditions, etc.

[0030] In this way, the rear differential 7 is constructed.

In the vehicle shown in FIG. 5, the rear wheels 13
, 15 is in a idling state, if the differential of the rear differential 7 is limited, the driving force sent to the other rear wheel via the rear differential 7 maintains drivability. If this differential limiting force is strengthened, the differential rotation between the rear wheels will be limited and the straight-line stability of the vehicle will be improved, and if the differential limiting force is moderately relaxed, smooth and stable turning will be possible.

As described above, since the response in the direction of relaxing the differential limiting force is good, the required turning performance can be obtained without time lag, and maneuverability is improved.

[0033] Even in an electromagnetic clutch in which an armature and an electromagnet are arranged facing each other, it is effective to arrange a non-magnetic material between them to improve the response. Further, the non-magnetic material may be separate from the armature, or may be integrated with the armature by coating or the like. Further, a non-magnetic material may be provided integrally or separately on the clutch plate side facing the armature. The non-magnetic material is appropriately selected from, for example, plastic, rubber, stainless steel, etc.

[0034]

[Effects of the Invention] The electromagnetic clutch of the present invention disposes a non-magnetic material between the armature and the electromagnet to block residual magnetism, which reduces the negative effect of residual magnetism on adjustment of fastening force and improves response. .

[Brief explanation of the drawing]

FIG. 1 is a cross-sectional view of a differential device using one embodiment.

FIG. 2 is a sectional view taken along line AA in FIG. 1;

FIG. 3 is an enlarged view of the main part of FIG. 1;

FIG. 4 is a graph showing characteristics of the embodiment shown in FIG. 1;

5 is a skeleton mechanism diagram showing a power system of a vehicle using the differential device of FIG. 1. FIG.

[Explanation of symbols]

73 Pilot clutch (friction clutch) 75
Armature 77 Thin plate (non-magnetic material) 79 Electromagnet

Claims (1)

[Claims] [Claim 1] A friction clutch, an electromagnet that applies magnetic force to the armature to operate the clutch, and a non-magnetic material that is placed between the armature and the electromagnet and transmits the magnetic force of the electromagnet but blocks residual magnetism. An electromagnetic clutch featuring