JP2002340036A - Electromagnetic clutch - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electromagnetic clutch that can develop a stable coupling characteristic by generating sufficient friction torque between a rotor and an armature plate and that is structurally simple, even in a reduced contact area between the rotor and the armature plate due to a reduced diameter. SOLUTION: In four attraction poles 7a to 7d arranged radially over a front end face of the rotor 7, two radially outer attraction poles 7a and 7b are smaller in area than two radially inner attraction poles 7c and 7d, the two radially outer attraction poles 7a and 7b are higher in magnetic flux density than the two radially inner attraction poles 7c and 7d to intensify a magnetic field, and the radially outer attraction poles 7a and 7b are higher in bearing pressure than the radially inner attraction poles 7c and 7d.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electromagnetic clutch, and more particularly to an electromagnetic clutch for transmitting a driving force from a driving source to a shaft of a refrigerant compressor.

[0002]

2. Description of the Related Art FIG. 5 is a longitudinal sectional view showing a conventional electromagnetic clutch, and FIG. 6 is a view showing the relationship between the distance from the center of the electromagnetic clutch and the contact surface pressure.

FIG. 6 shows a case where a friction member is arranged between two radially outer suction poles.

The electromagnetic clutch includes a hub plate 109 fixed to a shaft 102, a rotor 107 driven to rotate around the axis of the shaft 102, and a radially outer end face of a front end face of the rotor 107. Four suction poles 107a to 107d, an armature plate 114 provided on the hub plate 109,
The armature plate 114 is returned to its original position when the power supply is stopped, and includes an elastic body 120 interposed between the armature plate 114 and the hub plate 109.

[0005] The armature plate 114 is connected to the rotor 1.
07 is opposed to the front-side end face of the rotor 1 through a gap, and is attracted by the attracting poles 107a to 107d when energized.
07.

A conventional electromagnetic clutch has four suction poles 1
When the areas of 07a to 107d are defined as a, b, c, and d from the outside in the radial direction to the inside, respectively, the areas a, b, and
For example, a relationship of a: b: c: d = 1: 0.8: 0.9: 1.2 is established between c and d.

In recent years, there has been an increasing demand for a lighter electromagnetic clutch, and the diameter of the electromagnetic clutch has been reduced year by year.

As a result, the contact area between the rotor and the armature plate is reduced, and the contact surface pressure of the radially outer suction pole is reduced as shown by a dotted line in FIG. Since a high contact surface pressure cannot be obtained, it is difficult to secure a sufficient transmission torque with this electromagnetic clutch.

In particular, it is more difficult to secure a sufficient transmission torque at the time of starting the clutch which requires a large friction torque, and there is a problem that stable connection characteristics between the rotor and the armature plate cannot be obtained.

On the other hand, Japanese Patent Application Laid-Open No. 9-210096 discloses that a magnetic path is divided by embedding a non-magnetic material in a rotor having an inner armature facing the inner armature. A technique has been disclosed in which a large friction torque is secured when the clutch is activated to obtain good connection characteristics.

[0011]

SUMMARY OF THE INVENTION However, Japanese Patent Application Laid-Open No. Hei 9-2
In the electromagnetic clutch described in Japanese Patent No. 10096, the armature is formed of inner and outer armatures concentrically arranged via an annular space, and the inner and outer armatures are supported by elastic materials having different spring loads, respectively, and are attached to the rotor. A complicated configuration in which a nonmagnetic material is provided to divide the magnetic path is employed.

The present invention has been made in view of such circumstances, and an object of the present invention is to reduce the diameter of the rotor and the armature plate even when the contact area between the rotor and the armature plate is reduced. An object of the present invention is to provide an electromagnetic clutch which can generate a sufficient frictional torque to obtain stable coupling characteristics and has a simple structure.

[0013]

According to the first aspect of the present invention, there is provided a hub plate fixed to a shaft, a rotor driven to rotate about an axis of the shaft, Four suction poles arranged in the radial direction of the front end face, and an armature plate provided on the hub plate, opposed to the front end face of the rotor via a gap, and attracted to the suction pole when energized. An elastic body for returning the armature plate to its original position when the power supply is stopped, wherein, of the four attracting poles, the area of two radially outer attracting poles is changed to the radial inner side of the two attracting poles. It is characterized in that it is smaller than the area of the attraction electrodes.

When the armature plate is attracted to the rotor during energization, the magnetic flux density of the two radially outer attracting poles increases and the magnetic field becomes stronger, so that the contact surface pressure of the two radially outer attracting poles increases. And the friction torque increases.

According to a second aspect of the present invention, in the electromagnetic clutch according to the first aspect of the present invention, the areas of the four attracting poles are changed from a radially outer side to an inner side by a, b, and a, respectively.
where c, d, there is a relationship between the areas a, b, c, and d: a ≦ b = a + 0.05a a + 0.1a <c <a + 0.2a c <d <c + 0.3c I do.

The third aspect of the present invention is the first or second aspect.
In the electromagnetic clutch according to the present invention, a friction member is arranged between two radially outer suction poles.

The armature is not only attracted to the rotor, but also comes into contact with a friction member arranged between the two radially outer suction poles.

[0018]

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

FIG. 1 is a front view showing an electromagnetic clutch according to an embodiment of the present invention, and FIG. 2 is a sectional view taken along the line II-II in FIG.

The electromagnetic clutch includes a hub plate 9, a rotor 7, an armature plate 14, and a damper rubber (elastic body) 20.

The rotor 7 is rotatably supported by the boss 1a of the housing 1 of the refrigerant compressor via a radial bearing 5, and is provided with an engine (drive source) (not shown) about the shaft 2 of the refrigerant compressor as a center of rotation. Rotated by rotational force.

A pulley 12 is integrally provided on the outer peripheral surface of the rotor 7, and a belt (not shown) is wound around the pulley 12, and the rotor 7 is connected to a crankshaft of the engine via the belt.

The armature plate 14 is connected to the shaft 2 via the hub plate 9.

The friction surface 14f of the armature plate 14
Faces a friction surface (front end surface) 7f of the rotor 7 via a predetermined gap (gap) g, and is attracted when the electromagnetic coil 8 is energized. The gap g is depicted in FIG.

The electromagnetic coil 8 is accommodated in the annular space 4 of the rotor 7 and is fixed to the housing 1 via the connection fitting 3. The electromagnetic coil 8 is housed in an annular stator 8A.

The armature plate 14 has an annular space S
An outer armature plate 14A and an inner armature plate 14B are arranged concentrically through the outer armature plate 14A.

The hub plate 9 includes an outer annular portion 9A and an inner annular portion 9B. The outer annular portion 9A is fixed to the outer armature plate 14A by rivets 11, and the inner annular portion 9B is fixed to the shaft 2 by bolts 10.
It is fixed to.

An annular damper rubber 20 is fixed between the outer annular portion 9A and the inner annular portion 9B.

FIG. 3 is a partially enlarged view of the electromagnetic clutch of FIG.
FIG. 4 is a partially enlarged view of the rotor.

The rotor 7 has a magnetic flux bypass slot 15a opposed to the outer armature plate 14A via the friction member 13.

The rotor 7 is provided with a magnetic flux bypass slot 15b facing the inner armature plate 14B.

Four suction poles 7a to 7d are arranged on the friction surface 7f of the rotor 7 in the radial direction.

An annular groove 6 is provided between a suction pole 7a and a suction pole 7b on a friction surface 7f of the rotor 7, and a friction member 13 is accommodated in the annular groove 6. Note that the annular groove 6 may be provided on the friction surface 14 f of the armature plate 14, and the friction member 10 may be accommodated in the annular groove 6.

Part of the friction member 13 is a friction surface 7 of the rotor 7.
A predetermined amount protrudes from f toward the armature plate 14 side.

Assuming that the areas of the four attracting electrodes 7a to 7d are a, b, c, and d, respectively, from the outside to the inside in the radial direction, a ≦ b = a + 0. 05a a + 0.1a <c <a + 0.2ac <d <c + 0.3c.

Next, the operation of the above-described electromagnetic clutch will be described.

When the electromagnetic coil 8 is not energized, the armature plate 14 moves from the friction surface 7f of the rotor 7 to a predetermined gap g by the elastic force of the damper rubber 20.
(See FIG. 3).

Therefore, the belt and pulley 1
The driving force transmitted to the rotor 7 via the rotor 2 is not transmitted to the armature plate 14 side, and only the rotor 7 idles.

When the electromagnetic coil 8 is energized to generate an electromagnetic force, the damper rubber 20 is deformed in the axial direction and the armature plate 14 is attracted to the four attracting poles 7a to 7d.

Therefore, the gap g between the friction surface 14f of the armature plate 14 and the friction surface 7f of the rotor 7 becomes substantially zero, and the armature plate 14 is integrally connected to the rotor 7.

The driving force transmitted from the engine to the rotor 7 via the belt and the pulley 12 is first transmitted to the outer armature plate 14A, and the outer armature plate 14A rotates.

With the rotation of the outer armature plate 14A, the inner armature plate 1 connected to the outer armature plate 14A via the damper rubber 20.
4B rotates.

As a result, the inner armature plate 14
B also rotates in the same direction as the outer armature plate 14A, and the rotation is transmitted to the refrigerant compressor, and the refrigerant compressor is driven.

When the electromagnetic coil 8 is energized, a magnetic flux Φ is generated as shown by a two-dot chain line in FIG.
→ inner peripheral member 73 of rotor 7 → suction pole 7d → gap g →
Inner armature plate 14B → gap g → suction pole 7c → disk portion 72 of rotor 7 → suction pole 7b → gap g
→ The outer armature plate 14A → the gap g → the attracting pole 7a → the outer peripheral member 71 of the rotor 7 → the stator 8A and flows through the magnetic path.

At this time, the two radially outer attracting poles 7
The two attracting electrodes 7 whose areas a and b are radially inward.
Since the areas c and d are smaller than the areas c and d, the magnetic flux densities of the two attracting poles 7a and 7b on the outer side in the radial direction are smaller than those on the inner side in the radial direction.
It becomes larger than the attraction poles 7c and 7d, and the magnetic field becomes stronger.

Therefore, the outer armature plate 14
The contact surface pressure between the two radially outer suction poles 7a and 7b that absorb A increases, and the friction torque increases.

Since the outer armature plate 14A comes into contact with the friction member 13 disposed between the two radially outer attracting poles 7a and 7b, the friction torque of the two radially outer attracting poles 7a and 7b is large. Become.

The contact surface pressure with respect to the distance from the center of the electromagnetic clutch is shown by a solid line in FIG. The contact pressure is higher than the contact surface pressure of the attraction electrodes 107a and 107b.

According to this embodiment, the radially outer 2
Since the surface pressures of the attraction poles 7a and 7b are increased, even if the contact area between the rotor 7 and the armature plate 14 is reduced due to the small diameter, there is sufficient space between the rotor 7 and the armature plate 14. A high friction torque can be generated, and a stable connection characteristic can be obtained even at the time of starting the clutch that requires a large friction torque. In addition, the inner and outer armatures are each supported by an elastic material having a different spring load, and the rotor is provided with a non-magnetic material to divide the magnetic path (see JP-A-9-2110096). Can be easy.

Since the outer armature plate 14A is not only attracted to the rotor 7 but also comes into contact with the friction member 13 disposed between the two radially outer attracting poles 7a and 7b, the armature plate 14 and the rotor 7 Can be increased, and the occurrence of slip noise when the armature plate 14 is attracted to the friction surface 7f of the rotor 7 can be reduced.

In the above-described embodiment, the friction member 13 is accommodated in the annular groove 6 provided on the friction surface 7f of the rotor 7, but the annular space may be formed without accommodating the friction member 13 in the annular groove 6. .

[0052]

As described above, according to the electromagnetic clutch of the first or second aspect of the present invention, even if the contact area between the rotor and the armature plate becomes small due to the small diameter, the radius can be reduced. Since the contact surface pressure of the two suction poles on the outer side in the direction increases and the friction torque increases, a sufficient friction torque can be generated between the rotor and the armature plate to obtain stable connection characteristics. Moreover, it can be realized with a simple configuration.

According to the electromagnetic clutch of the invention, the friction torque between the armature plate and the rotor can be further increased.

[Brief description of the drawings]

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

FIG. 2 is a sectional view taken along the line II-II in FIG.

FIG. 3 is a partially enlarged view of the electromagnetic clutch of FIG. 2;

FIG. 4 is a partially enlarged view of a rotor.

FIG. 5 is a longitudinal sectional view showing a conventional electromagnetic clutch.

FIG. 6 is a diagram showing a relationship between a distance from the center of the electromagnetic clutch and a contact surface pressure.

[Explanation of symbols]

 2 Rotating shaft 7 Rotor 7a-7d Suction pole 9 Hub plate 6 Annular groove 13 Friction member 14 Armature plate 20 Damper rubber (elastic body) g Gap (gap)

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Akiyoshi Sekine 39, Higashihara, Chiyo-ji, Odai-gun, Osato-gun, Saitama Pref. 39, Higashihara, Zexel Valeo Climate Control Co., Ltd. (72) Inventor, Yukio Kazahaya Koyo, Osato-gun, Saitama Prefecture 39, Higashihara, Chiyo, Zexel Valeo Climate Control F-term (reference) 3H076 AA16 BB21 BB38 CC17

Claims (3)

[Claims] 1. A hub plate fixed to a shaft, a rotor driven to rotate around an axis of the shaft, and 4 arranged in a radial direction on a front end face of the rotor.
An armature plate provided on the hub plate, facing the front end face of the rotor via a gap, and being attracted to the attraction pole when energized, and the armature plate at the original position when energization is stopped. An electromagnetic clutch comprising: an elastic body that returns to the area of the at least one of the four attracting poles, wherein the area of the two radially outer attracting poles is smaller than the area of the two radially inner attracting poles. Characteristic electromagnetic clutch. 2. When the areas of the four attracting electrodes are a, b, c, and d, respectively, from the outside in the radial direction to the inside, a ≦ b = a + 0 between the areas a, b, c, and d. 2. The electromagnetic clutch according to claim 1, wherein a relationship of 0.05a a + 0.1a <c <a + 0.2ac <d <c + 0.3c is satisfied. 3. The electromagnetic clutch according to claim 1, wherein a friction member is disposed between the two radially outer suction poles.