JPH0531293Y2 - - Google Patents

Description

[Detailed Description of the Invention] <Industrial Application Field> The present invention relates to an electromagnetic clutch, and more particularly to an electromagnetic clutch that can suitably suppress the rotation of the driven side portion when the clutch is disengaged.

<Conventional Technology> Conventionally, in tillers, lawn mowers, etc., in order to intermittent power transmission from the engine to the power take-off shaft that connects the traveling device and the working equipment,
Some use electromagnetic clutches.

Regarding this electromagnetic clutch, for example,
As disclosed in Publication No. 133840, an annular stator core is fixed to a mounting plate fixed to a frame, a rotor is provided that faces the stator core and can rotate coaxially, and the stator core is excited. An annular armature is attached to the rotor to transmit power.

Furthermore, a brake cover is provided so as to surround the armature, and the armature is brought into elastic contact with the flange portion of the brake cover. Therefore, during demagnetization, the armature is braked by elastically abutting against the flange portion, so that the driven member connected via the belt to the pulley integral with the armature can be quickly stopped. This is to improve safety by simultaneously stopping a driven member such as the tiller of a tiller or the cutting blade of a lawnmower when the clutch is disengaged.

However, in the electromagnetic clutch having the above structure, since the brake cover serving as the brake structure is disposed so as to surround the armature, there is a problem in that the entire electromagnetic clutch device becomes large in size.

<Problems to be Solved by the Invention> In view of the problems of the prior art, the main purpose of the present invention is to provide an electromagnetic clutch that can prevent the driven member from rotating when the clutch is disengaged, and which can be made compact. Our goal is to provide the following.

<Means for Solving the Problems> According to the present invention, this purpose is to provide an annular excitation unit consisting of a coil and a yoke supported by a fixed frame, and an annular excitation unit disposed opposite to each other on an axial end face of the excitation unit. the clutch rotor, and an armature that is disposed opposite to the end surface of the clutch rotor in the axial direction and is rotatable relative to the clutch rotor, and the clutch rotor and the armature are energized by exciting the excitation unit. In an electromagnetic clutch that can be magnetically coupled to each other, the armature is substantially directly coupled to a prime mover, and the clutch rotor is coupled to a rotating shaft coupled to a driven machine. The excitation unit is connected to the clutch rotor via an elastic member having elastic force in the circumferential direction and the axial direction, and the excitation unit is supported by the fixed frame via a position adjustment means in the axial direction. Between the end faces facing the excitation unit,
An electromagnetic clutch characterized in that a friction material is interposed which is pressed against the opposing end surfaces of the clutch rotor and the excitation unit by the elastic force of the elastic member when the excitation unit is demagnetized. This is achieved by providing

<Operation> With this arrangement, when the excitation unit is demagnetized, the elastic restoring force of the elastic member brings the clutch rotor close to the excitation unit and frictionally engages the two, so that the clutch rotor You can prevent being dragged around. Further, since the axial position adjustment means changes the axial position of the excitation unit with respect to the fixed frame, the gap between the clutch rotor and the excitation unit can always be maintained at an appropriate level.

<Embodiments> Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

Figure 1 shows an electromagnetic clutch based on the present invention, in which a ring-shaped frame 2 is attached to the tip of a casing 1.
is attached, and a rotary shaft 4 of a cutting blade of a lawnmower, for example, is rotatably supported by a ball bearing 3 fixed to the inner circumference of the frame 2 and a bearing (not shown) inside the casing 1. .

Further, an annular yoke 5 is arranged coaxially with the rotating shaft 4. A plurality of stud bolts 6 are arranged on the axial end face of the annular yoke 5 so as to stand upright along the axis on concentric large and small circumferences, and each stud bolt 6
The yoke 5 is inserted through a hole 7 formed in the frame 2, a compression coil spring 8 is interposed between the axial end faces of the frame 2 and the yoke 5, and a nut 9 is screwed onto the stud bolt 6. is supported coaxially with the rotating shaft 4. Incidentally, an annular excitation coil 10 is received within the yoke 5, and an excitation unit 22 is thus constituted.

An armature 12 is rotatably supported at the tip of the rotating shaft 4 via a ball bearing 11, and a pulley portion 13 having a V-shaped groove is integrally formed on the outer periphery of the armature 12. The output shaft of the above-mentioned lawn mower engine is connected to the pulley portion 13 via a belt (not shown) that is hung around the pulley portion 13.

Between the yoke 5 and the armature 12 described above, there is a clutch rotor formed in an annular shape and having a U-shaped cross section so as to surround the yoke 5 over the inner circumferential surface, axial end surface, and outer circumferential surface of the yoke 5. 1
4 is interposed. This clutch rotor 14
A small sleeve 15 is fixed between both ball bearings 3 and 11 of the rotating shaft 4, and a large sleeve 16 is fixed to the inner peripheral surface of the clutch rotor 14. It is integrally attached to the rotating shaft 4 via an annular elastic member 17 as an interposed rubber damper. Further, an outward flange portion 18 is integrally formed on the outer peripheral portion of the yoke 5, and a resilient force is directed to bring the axial end surface of the outer peripheral wall portion 19 of the clutch rotor 14 close to the axial end surface of the flange portion 18. An initial deflection is given to the elastic member 17 so as to generate the following. Furthermore, a brake shoe 21 is provided on the axial end surface of the outer peripheral wall portion 19.
is installed, and the gap between the outward flange portion 18 and the outer peripheral wall portion 19 is made wider than between the clutch rotor 14 and the armature 12 to ensure the suction force between the clutch rotor 14 and the armature 12, and to increase the braking force. I'm trying to improve.

Furthermore, clutch rotor 14 and armature 12
In order to bypass and pass the magnetic flux generated when the excitation coil is excited to the inner circumference portion and the outer circumference portion of the armature 12, arc-shaped slots 20 are intermittently bored in the circumferential direction. There is.

In the electromagnetic clutch constructed in this manner, the elastic member 17 has flexibility in the axial direction by exciting the excitation coil 10 when the rotating shaft 4 is driven. is attracted, engine torque is transmitted to the clutch rotor 14 via the armature 12, and the rotating shaft 4 is rotationally driven. At this time, since the elastic member 17 has flexibility also in the circumferential direction, the clutch rotor 14 is attached to the armature 12.
The transmission shock at the time of adsorption, that is, startup, is suitably softened.

Next, when stopping, the excitation coil 10 is demagnetized, so that no attractive force is applied to the armature 12, and the clutch rotor 14 is moved to the elastic member 1.
Since the clutch rotor 14 is returned by the restoring force of 7 and separated from the armature 12, the clutch rotor 14 is no longer driven. At this time, the rotating shaft 4 tries to continue rotating due to the rotational inertia of the cutting blade as a driven member, but as described above, the brake shoe 21 attached to the outer peripheral wall 19 of the clutch rotor 14 Since the clutch rotor 14 elastically abuts and frictionally engages with the outward flange portion 18 of the clutch rotor 14, a braking force is applied to the clutch rotor 14, and the rotating shaft 4 is quickly stopped.
Furthermore, due to the elastic action of the elastic member 17 in the circumferential direction,
The shock when the rotating shaft 4 stops is alleviated.

By the way, since the yoke 5 is supported by the frame 2 via the stud bolt 6 as described above, the position of the yoke 5 can be adjusted in the axial direction by tightening or loosening the nut 9, and the clutch The state of contact between the brake shoe 21 provided on the outer peripheral wall portion 19 of the rotor 14 and the flange portion 18 of the yoke 5, that is, the contact force between the two due to the elastic force of the elastic member 17 can be suitably adjusted. Therefore, the braking force can be easily adjusted and readjusted when worn. Moreover, since the stud bolts 6 do not protrude radially outward from the outer peripheral surface of the yoke 5, the outer diameter of the electromagnetic clutch does not become large.

<Effect of the invention> As described above, according to the invention, by bringing the clutch rotor into resilient contact with the excitation unit and braking the clutch rotor, it is possible to quickly stop the clutch rotor when demagnetized. In addition, since there is no need to provide a separate brake structure, the electromagnetic clutch can be made compact as a whole, and the effect is extremely large.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an electromagnetic clutch based on the present invention. 2... Frame, 4... Rotating shaft, 5... Yoke, 6... Stud bolt, 7... Hole, 8... Compression coil spring, 9... Nut, 12... Armature, 14... Clutch rotor, 17...Elastic member, 22... Excitation unit.

Claims (1)

[Claims for Utility Model Registration] An annular excitation unit consisting of a coil and a yoke supported by a fixed frame, a clutch rotor disposed opposite to an axial end face of the excitation unit, and an axial end face of the clutch rotor. An electromagnetic clutch has an armature that is arranged to face each other and is rotatable relative to the clutch rotor, and the clutch rotor and the armature can be magnetically coupled to each other by exciting the excitation unit. The armature is substantially directly connected to the prime mover, and the clutch rotor is an elastic member having elastic force in the circumferential direction and the axial direction with respect to the rotating shaft connected to the driven machine. The excitation unit is supported by the fixed frame via a position adjusting means in the axial direction, and the excitation unit is connected between opposing end surfaces of the clutch rotor and the excitation unit. 1. An electromagnetic clutch characterized in that a friction material is interposed which is pressed against mutually opposing end surfaces of the clutch rotor and the excitation unit by the elastic force of the elastic member when the clutch rotor and the excitation unit are demagnetized.