JP3349733B2 - Clutch device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art An "electromagnetic clutch" is described in Japanese Utility Model Laid-Open Publication No. Hei 3-68634, and FIG. 7 shows a differential device 201 using the electromagnetic clutch. The differential device 201 includes a differential mechanism 205 disposed in a differential case 203 and a differential mechanism 2.
05 multi-plate type main clutch 207 to limit the differential
, A multi-plate type pilot clutch 209, an electromagnet 213 that attracts the armature 211 to fasten the pilot clutch 209, and, when the pilot clutch 209 is fastened, receives the differential torque of the differential mechanism 205 and the main clutch 207 by the cam thrust force. Ball cam 2 for fastening
15 is provided. Thus, each clutch 207,
209, the electromagnet 213, and the cam 215 limit the differential of the differential mechanism 205.

[0003]

SUMMARY OF THE INVENTION Main clutch 207
The clutch plate of the pilot clutch 209 and the clutch plate of the pilot clutch 209 have improved surface roughness and flatness by sliding, and the friction coefficient decreases before and after the durability test.
Reduce the connecting torque of As shown by the magnetic flux 217 in FIG. 7, the pilot clutch 209 forms a part of the magnetic circuit of the electromagnet 213.
In this case, when the surface roughness or flatness of the clutch plate is improved, the magnetic resistance is reduced and the magnetic flux 217 is increased. This increases the torque of the pilot clutch 209 and the cam 2
The main clutch 20
The torque of No. 7 is also improved.

As described above, in the initial stage, the change in the coupling torque of the clutch device is large due to the above-mentioned factors, for example, the yield in the durability test is poor, and the commercial value is reduced.

In view of the above, the present invention is directed to a clutch device which is configured such that when an electromagnetic pilot clutch is engaged, a torque is applied to a cam and the main clutch is engaged. It is an object of the present invention to provide a clutch device capable of suppressing a change in the entire coupling torque even if the change in the torque.

[0006]

A clutch device according to the present invention includes an electromagnet disposed outside a rotating case and having a yoke having a cross-sectional area perpendicular to a magnetic flux and a clutch plate disposed in the rotating case. And a multi-plate type pilot clutch having a cross-sectional area divided into sliding portions b and c, respectively, and an armature which is operated by magnetic force of an electromagnet passing through the yoke and these sliding portions to fasten the pilot clutch. , A friction type main clutch, and a cam that receives torque when the pilot clutch is engaged and engages the main clutch with a cam force, wherein the value of b / a or c / a is X, and a certain operating time elapses When the rates of change of the coefficient of friction in the later pilot clutch and the main clutch are y and z, respectively, y and x obtained in advance by experiments are
And y = αx + β (α and β were obtained by experiments)
Constant), z = γ (γ is a constant obtained by experiment)
From this z value and y · z ≒ 1, y = 1 / z, x =
(1-βγ) / αγ is obtained, and b / a = (1-βγ) /
From αγ, c / a = (1−βγ) / αγ, b for a
Alternatively, the values of a, b, and c are determined by obtaining the value of c with respect to a.

[0007]

The clutch plate of the pilot clutch is divided into radially outer and inner sliding portions via a magnetic cut-off portion, and the magnetic flux of the electromagnet is applied to the radially outer and inner portions of the yoke and to the sliding portions. The armature is moved and operated via a magnetic circuit having the unit and the armature as circuit members. Since the strength of the magnetic flux passing through the magnetic circuit is regulated at the point where the magnetic resistance is the highest in the circuit, the dimensions of each magnetic path member are determined so that the magnetic resistance is substantially uniform throughout the circuit. Accordingly, the yoke has a radially inner portion that is thicker and a cross-sectional area a perpendicular to magnetic flux is substantially the same between the outer portion and the inner portion, and the pilot clutch also reduces the areas b and c of the outer and inner sliding portions. Almost the same.

As described above, the improvement of the surface roughness and flatness of the pilot clutch acts on the one hand in the direction of reducing the coupling force between the pilot clutch and the main clutch, but on the other hand increases the magnetic flux of the magnetic circuit. This acts in a direction to increase the coupling torque of each clutch. Here, if the areas b and c of the sliding portion are too small compared to other cross-sectional areas (for example, a) of the magnetic circuit, when the surface roughness or the like is increased, the magnetic flux is increased rather than the torque decreased due to a decrease in the friction coefficient. When the torque increase is larger and the connection torque of the pilot clutch is increased, but when b and c are too wide compared to a,
The decrease in the torque due to the decrease in the coefficient of friction is larger and the coupling torque is reduced.

The coupling torque T of the clutch device is as follows: T = (friction coefficient of main clutch μm) × (number of friction surfaces of main clutch) × (radius of friction portion of main clutch) ×
Thrust force, Thrust force = Cam servo magnification × (Pilot clutch coupling torque Tp), Tp = (Pilot clutch friction coefficient μp) × (Pilot clutch friction surface number) × (Pilot clutch friction portion Radius) × attractive force by electromagnet.

Therefore, the decrease in T due to the decrease in μm is μ
It can be offset by increasing p and the attractive force of the electromagnet.

Accordingly, b and a with respect to a are set so that the coupling torque of the pilot clutch increases appropriately after the durability test.
By selecting the value of c, the decrease in the coupling torque of the main clutch due to the change in the friction coefficient is offset, and the change in the torque of the clutch device before and after the durability test can be suppressed to a small value.

That is, b / a or c / a is x, the rates of change of the friction coefficients of the pilot clutch and the main clutch before and after the endurance test are y and z, respectively, and the relational expression between y and x is obtained. against decided advance, x from the y Toko relation to y · z ≒ 1 determined in a from the value of the x
By determining c with respect to b and a, a change in the coupling torque of the clutch device before and after the durability test and a change in the characteristics in the operating state can be suppressed to a small degree, and the commercial value is improved. In addition, since it is possible to cope with the change in the friction coefficient of each clutch sliding portion, it is possible to use a sliding member having a rough surface roughness, thereby reducing the cost.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment will be described with reference to FIGS. The clutch device of this embodiment is used as a differential limiting device of the differential device shown in FIG. FIG.
1 shows a power system of a vehicle using the differential device of FIG. Hereinafter, the left and right directions are the left and right directions in this vehicle and FIGS. 1 and 2, and members and the like without reference numerals are not shown.

[0014] As shown in FIG.
Transmission 3, propeller shaft 5, rear differential 7 (differential device of FIG. 1 arranged on the rear wheel side),
Rear axles 9, 11, left and right rear wheels 13, 15, left and right front wheels 1
7, 19 and the like. In the rear differential 7, the differential case 21 (rotating case) is a differential carrier 23.
The ring gear 25 fixed to the differential case 21 meshes with the drive pinion gear 27. The drive pinion gear 27 is formed integrally with a drive pinion shaft 29 connected to the propeller shaft 5 side. Thus, the driving force of the engine 1 rotationally drives the differential case 21 from the transmission 3 via the propeller shaft 5.

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

In the differential case 21, a double pinion planetary gear type differential mechanism 35 is disposed. The internal gear 37 is formed on the differential case 21, and the sun gear 39 is formed on the left hub 31. Outer and inner pinion gears 41, 43 are pinion shafts 45, 45.
The pinion shaft 45 is rotatably supported above, and both ends of each pinion shaft 45 are supported by left and right pinion carriers 47 and 49. These pinion carriers 47 and 49 are integrated by welding, and the right pinion carrier 49 is connected to the right hub 3.
3 and are formed integrally.

Thus, the driving force of the engine 1 is transmitted from the differential case 21 (internal gear 37) to the pinion gear 4
The sun gear 39 (hub 31) and the right pinion carrier 49 (hub 33) are distributed via the wheels 1 and 43 to drive the left and right rear wheels 13 and 15. Further, when a driving resistance difference occurs between the left and right rear wheels, the driving force of the engine 1 is differentially distributed to each of the left and right sides by the rotation and revolution of the pinion gears 41 and 43.

A multi-plate type main clutch 53 is arranged between the cylindrical portion 51 of the pinion carrier 47 and the hub 31. A clutch ring 55 is arranged on the outer periphery of the hub 33, and the clutch ring 55 and the pinion carrier 49
Is provided with a ball cam 57 (cam).
A bearing 6 receiving a cam reaction force of the ball cam 57 is provided between the clutch ring 55 and the right side wall 59 of the differential case 21.
1 and a shim 63 are arranged.

A multi-plate pilot clutch 65 is disposed between the clutch ring 55 and the differential case 21. On the right side of the right side wall 59, a ring-shaped electromagnet 67 is disposed. The electromagnet 67 is supported by a right boss portion 69 of the differential case 21 via bearings 71, 71, and is attached to the differential carrier 23 via a support member. Fixed. An armature 73 is disposed on the left side of the pilot clutch 65, and the retaining ring 7 attached to the differential case 21 is provided.
5, the distance from the pilot clutch 65 is determined.

The electromagnet 67 has a coil 77 and a yoke 79, and forms air gaps 85 and 87 between the radially outer portion 81 and the inner portion 83 of the yoke 79 and the side wall 59 as shown in FIG. I have. The side wall 59 is divided by a stainless steel ring 89 to prevent a short circuit of the magnetic flux of the electromagnet 67, and the cylindrical portion 91 of the differential case 21 and the clutch ring 55 are made of stainless steel.

As shown in FIGS. 3 and 4, clutch plates 93, 95 on the outside and inside of pilot clutch 65 are provided.
Are voids 97, 99 formed at positions overlapping each other.
(Magnetic cut-off part) and are divided into sliding parts 101, 103, 105, 107 on the outside and inside in the radial direction, respectively. Here, the outer portion 81 of the yoke 79 and the sliding portion 10
The cross-sectional areas of 1, 103, 105 and 107 are a,
b and c (the unit is cm ² ). Also, the clutch plates 93, 9
5 are provided with oil grooves 109 and 111, respectively.

The electromagnet 67 attracts the armature 73 and fastens the pilot clutch 65 through a magnetic circuit 113 formed by the yoke 79, the air gaps 85 and 87, the side wall 59, the pilot clutch 65, and the armature 73.
When the pilot clutch 65 is engaged, the differential torque of the differential mechanism 35 is applied to the ball cam 57, and the main thrust is pressed and engaged via the pinion carriers 47, 49 by the cam thrust force.

The differential of the differential mechanism 35 is limited by the coupling force between the clutches 53 and 65. When the exciting current of the coil 77 is adjusted, the cam thrust force of the ball cam 57 changes due to the slip of the pilot clutch 65, and the main clutch 5
The coupling force of No. 3 changes, and the differential limiting force can be controlled. If the coupling force of the pilot clutch 65 is sufficiently increased, the differential is greatly limited by the coupling force of the clutches 53 and 65, or the vehicle is locked to improve the straight running stability of the vehicle. Is permissible and smooth and stable turning can be performed. Also, the pilot clutch 65
Is released, the cam thrust force disappears, the main clutch 53 is released, and the differential becomes free.

Thus, the rear differential 7 is formed.

After the rear differential 7 is assembled, a durability test is performed for a predetermined time. According to this durability test, the main clutch 53
And the coupling torque of the pilot clutch 65 change with changes in the respective friction coefficients μm and μp.
As described in the section, the change of the differential limiting force (the coupling force between the main clutch 53 and the pilot clutch 67) can be reduced by selecting the values of a, b, and c.

FIG. 5 shows the change in the connection torque (equal to the change in μP) y before and after the endurance test of the pilot clutch, and b / b
It is a graph with smaller value x of a and c / a. In this embodiment, a durability test was conducted using five types of pilot clutches having variously changed dimensions of a, b, and c as test pieces, and x and y of each test piece were plotted with + signs in FIG. = -0.7
A graph 11 expressed by an equation of 4x + 2.06 (α of the relational expression y = αx + β is −0.72 by experiment, β is 2.06)
5 was obtained. Perform a durability test of the main clutch 53 separately.
The change in m, z = 0.73 (γ was 0.73 by experiment) was obtained. Then, from the value of z and yz = 1, y = 1.7.
X and 0.93 were obtained from 3 and the above formula, and the values of b and c with respect to a were determined from this value.

Therefore, in the rear differential 7, the change in the characteristic of the differential limiting force before and after the durability test is extremely small, the yield of the durability test is increased, and the cost is reduced. Further, even after being mounted on the vehicle, the characteristic change is small and precise control of the differential limiting force becomes possible, so that the operability of the vehicle is improved. Also, since it corresponds to the change in the friction coefficient of each clutch in this way,
In each clutch, the friction member can be used with a rough surface roughness, and the cost is further reduced.

Since each circuit portion of the magnetic circuit has a uniform magnetic resistance, portions of the same material have substantially the same sectional area. Therefore, the cross-sectional area a of the yoke may be the radially inner portion, and x may be either b / a or c / a. or,
The clutch device of the present invention may be used not as a differential limiting device but as an intermittent torque device.

[0029]

According to the clutch device of the present invention, a friction type main clutch is fastened by a cam which receives torque via a multi-plate pilot clutch fastened by an electromagnet. The cross-sectional area of the magnetic path of the pilot clutch with respect to the area was determined according to the experimental value, and the decrease in torque of the main clutch after the durability test was compensated for by the increase in torque of the pilot clutch. Therefore,
The change in the coupling torque of the clutch device over time is extremely small, and the commercial value is improved.

[Brief description of the drawings]

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

FIG. 2 is an enlarged view of a main part of FIG.

FIG. 3 is a plan view of an outer clutch plate used in the embodiment.

FIG. 4 is a plan view of an inner clutch plate used in the embodiment.

FIG. 5 is a graph showing a relationship between a torque change of a pilot clutch before and after an endurance test and a magnetic path cross-sectional area ratio.

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

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

[Explanation of symbols]

 21 Differential case (rotating case) 53 Main clutch 57 Ball cam (cam) 65 Pilot clutch 67 Electromagnet 73 Armature 79 Yoke 93,95 Clutch plate 97,99 Air gap (magnetic shut-off part) 101,103,105,107 Sliding part

──────────────────────────────────────────────────続 き Continued on front page (58) Field surveyed (Int.Cl. ⁷ , DB name) F16D 27/115 F16H 48/20 F16H 48/30

Claims (1)

(57) [Claims] 1. An electromagnet having a yoke disposed outside the rotating case and having a cross section perpendicular to the magnetic flux and having a cross section a, and a clutch plate disposed inside the rotating case and having a cross section of b and c via a magnetic interrupting portion. A multi-plate pilot clutch divided into sliding parts, an armature that is moved and operated by magnetic force of an electromagnet passing through the yoke and these sliding parts to fasten the pilot clutch, a friction main clutch, and a pilot clutch When the clutch is engaged, the cam receives the torque and engages the main clutch by the cam force. The value of b / a or c / a is X, and the coefficient of friction of the pilot clutch and the main clutch after a certain operating time has elapsed. y change rate, respectively, when is z, obtained in advance by experiment
The relationship between y and x is y = αx + β (α and β are experimentally
), Z = γ (γ is a constant determined by experiment)
), And from the value of z and yz = 1, y = 1 /
z, x = (1−βγ) / αγ, and b / a = (1−
A clutch device, wherein the values of a, b, and c are determined by obtaining the value of b for a or the value of c for a from (βγ) / αγ, c / a = (1−βγ) / αγ .