JP3268691B2 - Electromagnetic clutch - Google Patents

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 a compressor of an automotive air conditioner.

[0002]

2. Description of the Related Art Generally, a compressor of a vehicle air conditioner is driven by transmitting the power of an external power source such as an engine via a belt or the like. Power is supplied to and removed from the compressor by an electromagnetic clutch provided at one end of a casing forming an outer shell of the compressor.

The electromagnetic clutch includes a magnetic rotor supported by one end of a casing and receiving power from an external power source;
A magnetic armature fixed axially movable to one end of a drive shaft drawn out of the casing and axially opposed to the end face of the rotor, and an excitation for generating magnetic attraction between the rotor and the armature And an electromagnetic coil as a means. When a current is applied to the electromagnetic coil, a magnetic attractive force is generated, and the armature is attracted to the rotor. As a result, the rotational torque of the rotor is transmitted to the drive shaft. The energization of the electromagnetic coil is generally controlled on / off.

[0004]

In the conventional electromagnetic clutch, when the electromagnetic coil is energized, the connection between the armature and the rotor is rapidly performed. That is, when the electromagnetic clutch shifts to the connected state, the rotor and the armature collide at a high speed. This is because the magnetic flux density between the rotor and the armature is increased as the distance between the rotor and the armature is reduced, and the magnetic attraction force is rapidly increased. As a result, the compressor suddenly shifts from the stopped state to the driven state, and receives a shock. This shock is transmitted to the occupants through the vehicle and gives the occupants discomfort.

In principle, it is also possible to avoid a high-speed collision between the rotor and the armature by controlling the amount of energization of the electromagnetic coil in accordance with the distance between the rotor and the armature. However, it is unavoidable that the distance between the rotor and the armature in the initial state varies, so that
It is actually difficult to make a correlation between the distance between the rotor and the armature and the amount of current supplied to the electromagnetic coil.

SUMMARY OF THE INVENTION It is therefore an object of the present invention to provide an electromagnetic clutch which does not need to control the amount of current supplied to an electromagnetic coil and prevents a sudden transition to a connected state.

Another object of the present invention is to provide an electromagnetic clutch in which a shock at the time of transition to a connected state is prevented with a simple configuration.

[0008]

According to the present invention, there is provided a rotor made of a magnetic material driven to rotate, an armature made of a magnetic material axially opposed to the rotor, and a magnetic attraction between the rotor and the armature. in the electromagnetic clutch comprising an excitation means for causing force, the rotor
And the armature in the axial direction opposing surfaces are each constituted by a plane.
And the radial end of the armature
A magnetic body projection facing the surface, wherein the magnetic body projection is provided.
Is the cross-sectional area in a direction perpendicular to the axis of the rotor,
It is set smaller in the far part compared to the part close to the rotor
And the radial dimension of the rotor
It should be set smaller in the far part than in the near part.
And an electromagnetic clutch characterized by the following.

[0009]

[0010]

[0011]

[0012]

[0013]

In the present invention, the armature made of magnetic material contacts the rotor via the non-magnetic material plate while overcoming the spring force by increasing the attraction force from the exciting means as the applied current value increases. Go to As they move, the contact force between them gradually increases, the amount of torque transmission increases, and no sudden shock occurs. On the other hand, when the torque is interrupted, the torque transmission amount gradually decreases.

[0014]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a view showing an electromagnetic clutch according to an embodiment of the present invention. As shown in FIG.
Comprises an armature 3 made of a magnetic material, a connecting portion connecting the armature and the drive shaft 1, and an exciting means for causing the armature 3 to generate a magnetic attraction between a part of the rotor 6. By means of the magnetic attraction of the means
The torque is transmitted between the rotor 6 and the drive shaft 1.

The drive shaft 1 is rotatably supported via a radial bearing 54 inside a cylindrical boss 53 protruding from one end of a casing 52. The rotor 6 is provided along the outer periphery and is formed in a cylindrical shape having a U-shaped cross section by a groove 6b opened to the casing 52 side.
Groove 6 for accommodating a belt connected to an external power source on the outer peripheral portion
a. The inner surface of the rotor 6 is rotatably supported via a radial bearing 51 around a boss 53 projecting from one end of the casing 52.

The armature 3 is made of a magnetic material, and is a ring-shaped plate provided at one end of the casing so as to face the rotor 6 in the axial direction.

The connecting portion includes a hub 2 fixed to one end of the drive shaft 1, a stopper plate 4 for preventing the armature 3 from moving outward in the axial direction, and a leaf spring 5 for connecting the hub 2 and the armature 3. And a fixing nut 11 screwed to one end of the drive shaft to fix the hub 2 to the drive shaft 1.

Further, the rotor 6 is cylindrical and rotated by an external power source. A non-magnetic plate made of a non-magnetic thin plate (not shown) is arranged on the surface of the rotor 6 facing the armature 3. Further, an electromagnetic coil 7 is provided in the groove 6b of the rotor 6 as exciting means.

In the electromagnetic clutch 10 having such a configuration, when an electric current is passed through the electromagnetic coil 7, the generated magnetic flux causes the one end face 6 of the rotor 6 to be rotated by an external power source.
c, the one end face 3b of the armature 3 is sucked, comes into contact with the suction surface 9a of the nonmagnetic plate 9 made of a nonmagnetic thin plate, and rotates, so that the torque of the rotor 6 is applied to the armature 3 by the leaf spring 5 2 and drive shaft 1 communicating via
To drive a drive mechanism (not shown).

FIG. 2 is a partially enlarged sectional view schematically showing a main part of the electromagnetic clutch of FIG. As shown in FIG. 2, a magnetic body projection 8 is formed outside one end of the rotor 6.
The protruding portion 8 has a conical cylindrical shape with a gradually decreasing cross-sectional area, and has a cross-sectional area in a direction orthogonal to the axis of the rotor 6.
In addition, the radial dimension of the rotor 6 is set smaller in a portion farther than the portion near the rotor 6, and the tip is sharper than the portion closer to the rotor 6. It has a structure called a solenoid.
A non-magnetic plate 9 is provided on a surface of the rotor 6 facing the armature 3.

FIGS. 3A and 3B are diagrams showing examples of the waveform of the current applied to the electromagnetic coil 7 of FIG. FIG.
The operation when a normal DC current is applied to the electromagnetic clutch according to the embodiment of the present invention will be described with reference to FIG. When a normal DC current as shown in FIG. 3 (a) flows through the electromagnetic coil 7, a part of the magnetic flux generated in the electromagnetic coil 7 is reduced as shown by arrows 12a to 12d in FIG. It flows into the surface 3a and the one end surface 3b. Here, the magnetic material projecting portion 8 is formed so that its cross section becomes narrower as it moves to the left in FIG.
The amount of magnetic flux from is gradually reduced.

Therefore, when a current is passed through the electromagnetic coil 7, the end of the armature 3 (adsorbed surface) is brought into contact with the attracting surface 9 a of the nonmagnetic plate 9 of the rotor 6 by the action of the electromagnetic coil 7 from the state of FIG. Plane) 3b approaches. However, as the suction surface 3b of the armature 3 approaches the suction surface 6c of the rotor 6, the outer peripheral surface 3a of the armature 3 and the rotor 6
The area facing the magnetic material protrusion 8 is increased, and the magnetic material protrusion 8
And the amount of magnetic fluxes 12a and 12b passing therethrough increases. For this reason, the amount of magnetic fluxes 12c and 12d passing through the non-magnetic plate 9 where the attracting surface 6c of the rotor 6 and the attracted surface 3b of the armature 3 substantially generate an attraction force do not increase sharply. As a result, the attraction force between the attracted surface 3b and the attraction surface 6c does not suddenly increase, and the armature 3 is attached to the attraction surface 6c of the rotor 6 together with the return force of the leaf spring 5 (see FIG. 1).
Of the non-magnetic plate 9 is prevented from violently colliding with the attracted surface 3b of the armature 3 to receive a shock, and the torque is not suddenly transmitted. It is done gradually.

As shown in FIG. 3B, the current may be supplied to the electromagnetic coil 7 by increasing the time constant of the current. In this case, the current value reaches a peak after drawing an upwardly increasing curve and then draws a downwardly decreasing curve. The amount of magnetic flux generated by the electromagnetic coil 7 draws a similar curve with a magnitude proportional to the curve of FIG. In the first area of the increase curve, the surface 3 to be attracted of the armature 3 is increased as the amount of magnetic flux increases.
The force that strongly pulls b gradually increases,
Similarly to the above, the facing area between the outer peripheral surface 3a of the armature 3 and the magnetic projection 8 of the rotor 6 increases, and the amount of magnetic flux passing through the magnetic projection 8 greatly increases. Therefore, the effective magnetic flux amount for suction gradually increases, and the armature 3
As the attracted surface 3b of the armature 3 approaches the attracting surface 6c of the rotor 6, the attracted surface 3b of the armature 3 with respect to the attracting surface 6c of the rotor 6 suppresses the approach speed, and the armature 3 contacts the attracting surface 9a of the non-magnetic plate 9. It is possible to lessen the shock of the attracted surface 3b due to a vigorous collision than that shown in FIG. 3 (a), and even after the contact, the torque is rapidly transmitted by the contact force corresponding to the increase in the current value. It is done gradually without. On the other hand, the current value flowing through the electromagnetic coil 7 gradually decreases even at the time of interruption, so that the attracted surface 3b of the armature 3 with respect to the attracting surface 6c of the rotor 6 gradually separates against the returning force of the leaf spring. Since the speed does not increase rapidly, the torque is cut off slowly.

[0025]

As described above, according to the present invention,
Shock during intermittent torque can be reduced, and a long-life electromagnetic clutch can be provided.

[Brief description of the drawings]

FIG. 1 is a view showing an electromagnetic clutch according to an embodiment of the present invention.

FIG. 2 is a partial sectional view showing a main part of the electromagnetic clutch of FIG.

FIG. 3 is a diagram showing a waveform of a current applied to the electromagnetic clutch shown in FIGS. 1 and 2, and FIG. 3 (a) is a diagram showing normal on / off. (B) is a diagram showing ON / OFF when the time constant of the electromagnetic coil is large or a delay circuit is incorporated in the circuit.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Drive shaft 2 Hub 3 Armature 3b Surface to be attracted 4 Stopper plate 5 Leaf spring 6 Rotor 6c Attraction surface 7 Electromagnetic coil 8 Magnetic projection 9 Non-magnetic plate 9a Attraction surface 51 Radial bearing

Claims (2)

(57) [Claims] 1. A rotor comprising: a rotor made of a magnetic material driven to rotate; an armature made of a magnetic material axially opposed to the rotor; and exciting means for generating a magnetic attraction between the rotor and the armature. In the electromagnetic clutch, an axial pair of the rotor and the armature
The facing surfaces are each configured by a plane, and the rotor is
With a magnetic projection facing the radial end face of the armature
And the magnetic material protrusion is perpendicular to the axis of the rotor.
The cross-sectional area in the direction of
Part is set smaller and the rotor
At the part far from the part close to the rotor
An electromagnetic clutch characterized by being set small . 2. The electromagnetic clutch according to claim 1 , wherein
The magnetic body protrusion has a radial dimension of the rotor,
An electromagnetic clutch characterized in that it gradually decreases as the distance from the rotor increases.