JPH036376B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a magnetic powder type electromagnetic clutch, and more particularly to a technique for preventing powder lock phenomenon during clutch operation and reducing drag torque.

It has a drive member that has an inner friction surface and is driven to rotate around the center line, and an outer friction surface that is separated from the inner friction surface by a predetermined gap, and the gap is filled with magnetic particles using magnetic force. a driven member to which the rotation of the driving member is transmitted by being rotated; and an annular groove that is fixed to the driving member and opens outward on the inner peripheral side of the side edge of the gap; A magnetic particle type electromagnetic clutch has been proposed which includes a labyrinth member that forms a labyrinth between the two. However, according to such a clutch, when the rotation of the drive member decreases and the magnetic particles stuck to the inner circumferential friction surface due to centrifugal force fall due to gravity, they are received by the annular groove.
The received magnetic particles flow in the circumferential direction along the annular groove, and it is inevitable that the magnetic particles are unevenly distributed in a portion located below the inner circumferential friction surface. Therefore, when the clutch is operated, the dragging torque may increase due to the unevenly distributed magnetic particles, or a powder lock phenomenon may occur where magnetic particles are packed between the driving member and the driven member and they lock together. It is.

The present invention has been made against the background of the above circumstances, and its object is to provide a magnetic powder type electromagnetic clutch that is free from the powder lock phenomenon during clutch operation and has low drag torque.

In order to achieve such an object, the present invention provides an annular groove of the labyrinth member that is divided in the circumferential direction to prevent the flow of magnetic particles received in the annular groove in the circumferential direction. It is characterized by the provision of a plurality of blocking partition walls.

In this way, the magnetic particles received in the annular groove of the labyrinth member are prevented from flowing in the circumferential direction by the partition wall, so that the magnetic particles are unevenly distributed in the lower portion of the inner peripheral friction surface. Therefore, the powder lock phenomenon and increase in dragging torque during clutch operation are suitably eliminated.

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described in detail below based on the drawings.

The clutch shown in FIG. 1 is a clutch applied to an automobile, and is built into a clutch housing 2 fixed to an engine (not shown). It is something that can be transmitted or blocked.

A disk 8 is fixed to the end of the crankshaft 4, and a yoke 14 as a driving member consisting of a first yoke member 10 and a second yoke member 12 is fixed to this disk 8. The yoke 14 has a cylindrical shape and includes an excitation coil 16 therein and an inner friction surface 18 on its inner circumferential surface. Further, a front labyrinth member 20 and a rear labyrinth member 22 are fixed to the yoke 14, and the rear labyrinth member 22 is integrally provided with a cylindrical bearing case 24.

A ball bearing 26 is disposed within the bearing case 24, and a boss portion 29 of a rotor 28, which is a driven member, is rotatably supported by the ball bearing 26. Rotor 28
is inside the yoke 14 and concentrically with the yoke 14,
and is provided so as to be relatively rotatable, and the rotor 28
The outer peripheral friction surface 30 faces the inner peripheral friction surface 18 with a small gap 32 in between. And an annular space 34 that is substantially closed by the yoke 14, both labyrinth members 20 and 22, and the rotor 28.
is formed, and a predetermined amount of ferromagnetic material powder 36, which is magnetic powder, is enclosed in this annular space 34. The front labyrinth member 20 and the rear labyrinth member 22 are very close to the rotor 28 at their tips, so that the powder 3
6 is prevented from leaking to the outside of the annular space 34. The rotor 28 is an annular member, and two plates 38 and 40 are attached to the bolts 42 inside the rotor 28.
The plates 38 and 40 carry a plurality of equally angularly spaced rubber torsion springs 44.

On the other hand, a clutch hub 48 is attached to the spline shaft portion 46 of the output shaft 6 so as to be slidable in the axial direction and relatively rotatable. This clutch hub 48 consists of two plates 3 fixed to the rotor 28.
8 and 40, and has an opening 50 large enough to accommodate the torsion spring 44. Rotation of rotor 28 is transmitted to clutch hub 48 via plates 38 and 40 and torsion spring 44.

Further, a slip ring 52 is fixed to the outer peripheral surface of the bearing case 24, and this slip ring 52 comes into sliding contact with a brush 56 held by a phenolic resin bracket 54 fixed to the clutch housing 2. Conductive member 58
Electric power is supplied to the excitation coil 16 via the conductive wire 60.

The labyrinth members 20 and 22 are made of a non-magnetic material such as an aluminum alloy or a copper alloy. By forming an annular wall 64 that has a large diameter, an annular groove 66 that opens outward on the inner peripheral side of the side edge of the gap 32 is formed, and the ferromagnetic material powder falls from the vicinity of the gap 32 according to gravity. 36
is now available. In the annular groove 66 of the front labyrinth member 20, a second
As shown in the figure and FIG. 3, eight partition walls 68 made of non-magnetic material divide the annular groove 66 into eight equal parts in the circumferential direction.
are integrally formed to prevent the ferromagnetic powder 36 received in the annular groove 66 from flowing circumferentially under the force of gravity. In the rear labyrinth member 22 as well, an annular groove 70 is formed by forming an annular wall 69 that becomes larger in diameter as it approaches the crankshaft 4 side, and a plurality of partition walls are formed in the annular groove 70. 71 in the circumferential direction.

The effects of this embodiment will be explained below.

When the exciting coil 16 is energized and the yoke 14 is excited, a magnetic circuit is formed as shown in FIG. 4B. A gap 32 formed between the inner friction surface 18 and the outer friction surface 30 is filled with powder 36 by magnetic force, and the rotation of the crankshaft 4 is transmitted to the output shaft 6.

In the above state, when the supply of current to the excitation coil 16 is cut off and the yoke 14 is brought into a non-excited state, the magnetic circuit B formed up to that point disappears and the powder 36 is stuck to the inner circumferential friction surface 18 of the yoke 14 in a layered manner due to centrifugal force.

In the above state, when the engine is stopped and the rotation of the crankshaft 4 is stopped accordingly, the powder 36 that had been stuck on the inner circumferential friction surface 18 falls according to gravity, and the labyrinth member It is received within annular grooves 66, 70 provided in 20,22. In the front labyrinth member 20, the inside of the annular groove 66 is divided into many parts in the circumferential direction by the partition walls 68, so that the powder 36 received in the annular groove 66 is separated in the circumferential direction by the partition walls 68. Since the flow of the powder 36 is prevented, the powder 36 is prevented from falling onto the inner circumferential friction surface 18 located below and being unevenly distributed. FIG. 2 shows this state. Also, in the rear labyrinth member 22,
The circumferential movement of the powder 36 received in the annular groove 70 is similarly prevented by the partition wall 71.

Therefore, the labyrinth member 2 shown in FIG.
In the conventional clutch in which 0' is used, the powder 36 received in the annular groove 66' further flows in the circumferential direction shown by arrow C under gravity, as shown in FIG. The powder 36 is accumulated on the lower part of the inner peripheral friction surface 18, filling the gap 32, and when the engine is restarted, excessive torque is temporarily transmitted to the output shaft 6 regardless of the de-energized state of the yoke 14. However, according to this embodiment, the flow of the powder 36 in the circumferential direction within the annular groove 66 is prevented. Therefore, the powder 36 is prevented from accumulating in the portion located below the inner circumferential friction surface 18, and this inconvenience is completely eliminated.

As described above, according to this embodiment, when the crankshaft 4 is not rotating or rotating at low speed, the powder lock phenomenon and the dragging phenomenon caused by the powder 36 being unevenly distributed according to gravity are completely eliminated. Then, the front labyrinth member 2 is inserted into the annular groove 66.
Since the partition wall 68 formed integrally with the powder 36 and the yoke 14 increases the heat dissipation area and improves the cooling performance, there is an advantage that the durability of the powder 36, the yoke 14, etc. is improved.

Moreover, the temperature rise of the excitation coil 16 is also suppressed due to the improved cooling performance. For this reason, the excitation coil 16 is generally driven at a constant current in order to obtain a constant torque transmission performance regardless of its temperature rise, so in such a case there is an advantage that the power consumption of the excitation coil 16 is reduced.

Although the embodiment of the present invention has been described above based on the drawings, the present invention can also be applied to other aspects.

For example, as shown in FIGS. 8 and 9, the partition wall 72 that divides the annular groove 66 in the circumferential direction is composed of a pair of opposing inclined walls 74 and has a V-shape that opens outward. It is okay to do so. In such a case, the powder 36 is also received between the inclined walls 74, and the powder 36 is absorbed when the crankshaft 4 is stopped.
6 is further prevented from being unevenly distributed, and the cooling effect at the clutch is further enhanced.

The above-mentioned embodiment is merely one embodiment of the present invention, and various modifications may be made to the present invention without departing from the spirit thereof.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing an example in which the present invention is applied to a clutch for an automobile. 2 and 3 are a front view and a perspective view of a front labyrinth member provided in the clutch of FIG. 1, respectively. Figures 4 and 5 are explanatory diagrams of the operation of the clutch in Figure 1. Figure 4 shows the state of magnetic particles when energized, and Figure 5 shows the state of magnetic particles when not energized while the drive member is rotating. . FIG. 6 is a diagram corresponding to FIG. 3 showing a conventional front labyrinth member. FIG. 7 is a diagram showing the state of magnetic particles in a conventional clutch equipped with the member shown in FIG. 6 while the drive member is stopped. FIGS. 8 and 9 each show other embodiments of the present invention and correspond to FIG. 2. 14: Yoke (driving member), 18: Inner peripheral friction surface,
{20: Front labyrinth member, 22: Rear labyrinth member} (Labyrinth member), 28: Rotor (driven member), 30: Outer peripheral friction surface, 32: Gap, 36: Ferromagnetic material powder (magnetic powder), 66, 7
0: Annular groove, 68, 71, 72: Partition wall.

Claims (1)

[Scope of Claims] 1. A drive member having an inner circumferential friction surface and driven to rotate around a center line, and an outer circumferential friction surface separated from the inner circumferential friction surface by a predetermined gap, and having a drive member that is rotatably driven around a center line. A driven member to which the rotation of the driving member is transmitted by being filled with magnetic particles by magnetic force, and an annular groove that is fixed to the driving member and opens outward on the inner peripheral side of the side edge of the gap. and a labyrinth member forming a labyrinth between the driven member and the magnetic particle falling according to gravity is received in the annular groove, the labyrinth member A magnetic particle type electromagnetic device characterized in that a plurality of partition walls are provided in the annular groove to divide the annular groove in the circumferential direction and prevent the magnetic particles received in the annular groove from flowing in the circumferential direction. Clutch.