192 clutches and power-stop control – Clutches – Operators
Reexamination Certificate
1999-09-21
2001-04-03
Bonck, Rodney H. (Department: 3681)
192 clutches and power-stop control
Clutches
Operators
C192S03000R, C192S084961, C192S200000
Reexamination Certificate
active
06209699
ABSTRACT:
CROSS REFERENCE TO RELATED APPLICATION
This application is based on and incorporates herein by reference Japanese Patent Application Nos. Hei. 10-268517 filed on Sep. 22, 1998 and Hei. 11-65341 filed on Mar. 11 1999.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an electromagnetic clutch suitable for use in a compressor of an automotive air conditioning system.
2. Description of Related Art
An electromagnetic clutch used for a compressor of an automotive air conditioner includes a rotor and an armature. The rotor rotates by receiving a rotational force from a vehicle engine, and the armature is placed to face the rotor with a predetermined slight gap. The armature is connected to a compressor shaft through a hub. In general, there are two types of hub constructions.
In a plate spring type hub construction, one end of the plate spring is connected to an inner hub mounted on the compressor shaft, and another end of the plate spring is connected to the armature.
In a rubber type hub construction, an inner area of a disk-shaped elastic member made of rubber is connected to an inner hub mounted on the compressor shaft, and an outer area is connected to the armature through a cylindrical support plate.
The plate spring type hub construction has no damping mechanism to reduce vibration and torque pulsation from the armature to the hub. Thus, clutch operation noise and torsional resonance of the clutch are not reduced.
In the rubber type hub construction, the resiliency of the elastic member must be sufficient to separate the armature from a friction surface of the rotor when an electromagnet is deenergized. Therefore, the axial dimension of the disk-shaped elastic member must be larger than that of the plate spring arrangement. As a result, the axial dimension of the clutch is enlarged.
JP-U-61-194831 discloses an electromagnetic clutch in which a plate-like elastic member and a rigid plate are provided to position an armature opposite to a rotor. The armature, the plate-like elastic member and the rigid plate are adhesively connected to each other, and the rigid plate is connected to an inner hub through plural plate springs. That is, a collision noise when the armature is coupled to the rotor is reduced by the damping function of the elastic member.
However, in this prior art, the rigid plate supporting the plate-like elastic member is connected to the inner hub by plural separated plate springs, thereby increasing the number of parts and manufacturing cost.
SUMMARY OF THE INVENTION
An object of the present invention is to provide an electromagnetic clutch having a simple structure, and having the advantages of both the plate spring type hub and the rubber type hub.
According to a first aspect of the present invention, a spring plate member is connected to a hub. The spring plate member includes an arm-like plate spring portion generating a resilient force to separate an armature from a rotor, and an outer ring portion integrally formed with the plate spring portion. Here, the outer ring portion faces the armature. An elastic member is provided between the armature and the outer ring portion for connecting the armature directly with the outer ring portion.
Thus, shock and vibration when the armature is coupled to the rotor are reduced by the elastic member. Similarly, torsional resonance caused by the torque vibration of the compressor is reduced. Therefore, operation noise of the electromagnetic clutch is efficiently reduced.
Further, when the clutch is disengaged, the armature is returned to its original position by the resilient force of the plate spring portion, thus the elastic member need not return the armature. Therefore, the elastic member can be formed as a thin plate along the radial direction of the armature and the outer ring portion. Thus, the axial dimension of elastic member can be made much smaller than that of conventional clutch having a rubber type hub.
Further, even when a rotation apparatus operated by the clutch is locked, the elastic member can melt by the heat generated by friction from the armature rubbing against the rotor. This causes the spring plate member to disconnect from the armature. That is, the elastic member works to limit torque transmission. Therefore, an excessive load condition caused by the lock of the rotation apparatus is stopped. Accordingly, a V-belt driving the rotor is not damaged and the temperature of the friction surface does not significantly increase, as would happen if the excessive load condition continued for a long time.
Additionally, the armature is directly supported by the elastic member, and the outer ring portion is integrated with the arm-like plate spring portion. Thus, the structure is much more simple in comparison with that in JP-U-
61-194831
, and easily assembled, thereby reducing the manufacturing cost.
According to second aspect of the present invention, a spring plate member is connected to a hub, and the spring plate member includes an arm-like plate spring portion generating a resilient force to separate an armature from a rotor. A separate outer ring portion is connected to the spring plate member and faces the armature. A radially outer portion of the arm-like plate spring portion is connected to the outer ring portion. Further, an elastic member is provided between the armature and the outer ring portion for connecting the armature directly with the outer ring portion.
Thus, the elastic member is attached to the outer ring portion and the armature while the outer ring portion is separate from the spring plate member, thereby simplifying the attachment process. Further, the outer ring portion and the spring plate member are formed independently, thus shapes of these elements can be simplified.
According to third aspect of the present invention, a spring plate member is connected to a hub. The spring plate member includes a saucer-like plate spring portion generating a resilient force to separate an armature from a rotor. An elastic member is provided between the armature and the saucer-like plate spring portion for connecting the armature directly with the saucer-like plate spring portion.
Thus, the plate spring portion is completed disk, thereby reducing the manufacturing cost of the spring plate member. As a result, an electromagnetic clutch having same effect of the first aspect of the present invention can be provided with a small cost.
REFERENCES:
patent: 2407757 (1946-09-01), MacCallum
patent: 3455421 (1969-07-01), Miller
patent: 4187939 (1980-02-01), Silvestrini et al.
patent: 5377799 (1995-01-01), Mullaney
patent: 5642798 (1997-07-01), Muirhead et al.
patent: 5944158 (1999-08-01), Okazaki
patent: 49-132357 (1974-11-01), None
patent: 60-138035 (1985-09-01), None
patent: 61-194831 (1986-12-01), None
patent: 6-159394 (1994-06-01), None
patent: 8-121503 (1996-05-01), None
Hayashi Toshihiro
Tabuchi Yasuo
Tobayama Masashi
Bonck Rodney H.
Denso Corporation
Pillsbury & Winthrop LLP
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