Pumps – Correlated pump and motor or clutch control
Reexamination Certificate
2001-06-04
2003-07-29
Freay, Charles G. (Department: 3746)
Pumps
Correlated pump and motor or clutch control
C192S08200T, C192S084961
Reexamination Certificate
active
06599102
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to a gas compressor which receives compressive power from outside through an electro-magnetic clutch and to an air conditioning system having this gas compressor.
2. Description of the Related Art
Many of the vane-rotary-type gas compressors, scroll-type gas compressors, swash-plate-type gas compressors, etc. used in automotive air conditioners, GHP or the like, receive drive power from outside through an electro-magnetic clutch. An example in which an electro-magnetic clutch is used in a vane-rotary-type gas compressor will be described with reference to
FIGS. 1 and 2
. An electro-magnetic clutch
10
is mounted to a case cover
23
provided in the outer periphery of one end portion of a rotor shaft
22
retaining a rotor
21
equipped with vanes
20
. More specifically, stationary portions of the electro-magnetic clutch
10
which do not rotate, that is, an annular core
11
and a coil
12
provided inside the core
11
, are mounted to an intermediate shoulder end surface
23
a
of the case cover
23
by means of a retaining ring
13
a
through the intermediation of a core flange portion
13
of the core
11
. The core flange portion
13
has a protrusion
13
b
, which is fitted into a recess
23
b
of the intermediate shoulder end surface
23
a
of the above-mentioned case cover to thereby prevent rotation of the core
11
.
Further, in the rotatable driven portion of the electro-magnetic clutch, an armature friction plate
14
, a buckling
15
, an elastic coupling body
16
, a base plate
17
, and a hub
18
are connected together. The hub
18
is further connected to the rotor shaft
22
.
The manner in which the above-mentioned components are connected will be described more specifically. The armature friction plate
14
and the buckling
15
are connected to each other by means of a plurality of joint pins
15
a
. The buckling
15
and the base plate
17
are integrally connected to each other by the elastic coupling body
16
, which is formed of torsional rubber. When the armature friction plate
14
is attracted by the magnetic force of the clutch, the elastic coupling body
16
undergoes elastic deformation. The base plate
17
and the hub
18
are connected to each other by means of a plurality of joint pins
17
a
. The hub
18
is fastened to one end of the rotor shaft
22
by means of a spline
24
so as to be connected to a compressor main body
25
side.
The rotatable driving portion of the electro-magnetic clutch comprises a pulley
26
formed of a magnetic material, and this pulley
26
is mounted to the case cover
23
through the intermediation of a ball bearing
27
.
In the pulley
26
, an inner peripheral portion
26
a
forming a bearing housing and an outer peripheral portion
26
c
having pulley grooves
26
b
in the outer periphery thereof are connected to each other on a pulley end surface
26
d
side so as to define a U-shaped sectional configuration, and the core
11
is accommodated in the recess thus defined. Numeral
19
indicates holes for forming a magnetic circuit between the armature friction plate
14
and the pulley
26
.
When the above-described gas compressor is used in an automotive air conditioner, the pulley
26
on the driving side is rotated by a belt (not shown) entrained about it and about the output shaft of the engine. When the electro-magnetic clutch
10
is not energized, the armature friction plate
14
on the driven side is spaced apart from the pulley
26
, and does not rotate. In this state, the gas compressor is at rest.
When electric current is supplied to the coil
12
of the electro-magnetic clutch
10
to energize the same, the armature friction plate
14
is attracted by the end surface
26
d
of the pulley
26
due to the magnetic flux of the coil, whereby the driving side and the driven side of the electro-magnetic clutch
10
are integrated with each other, causing the rotor shaft
22
to rotate. In this state, the gas compressor is operating, with the elastic coupling body
16
undergoing elastic deformation.
In the conventional gas compressor, burning of the electro-magnetic clutch or rupture of the belt can happen during operation, though on rare occasions. On examination, it has been found that such trouble is attributable to the following phenomena.
(1) Anomalous Heat Generation of the Ball Bearing
27
When the ball bearing
27
generates more heat than usual due to poor lubrication, wear, etc. and attains a high temperature as shown in
FIG. 7
, the heat is transmitted to the core
11
of the electro-magnetic clutch
10
, which is beside the ball bearing surface and which surrounds the outer periphery of the bearing, and the core
11
also attains a high temperature, with the result that the mold thereof is melted, which may cause short-circuiting of the wiring. Further, the coil
12
and the portion of the pulley
26
near the end friction surface
26
d
also attain a high temperature, resulting in a reduction in the magnetomotive force of the electro-magnetic clutch
10
, as shown in FIG.
8
.
The reduction in the magnetomotive force weakens the attracting force acting between the pulley
26
and the armature friction plate
14
, and slippage occurs therebetween, thereby generating sparks. Further, the frictional heat generated causes an increase in the ambient temperature, thereby destroying the elastic coupling body
16
made of rubber. In this state, the armature friction plate
14
comes into contact with the hub
18
, and frictional heat is generated to thereby generate sparks, with the result that the core
11
undergoes further temperature rise. Further, the rotor shaft
22
ceases to rotate in the normal manner.
When the temperature of the core
11
exceeds 200° C., the mold is softened and melted. If such an acute temperature rise can be detected before this temperature level is reached, this trouble could be prevented.
(2) Anomalous Heat Generation of the Electro-magnetic Clutch
When rotation is continued after the breakage of the ball bearing
27
, the core
11
and the pulley
26
, which are spaced apart from each other by a small gap, come into contact with each other, and the resultant frictional heat causes a rapid temperature rise in the core
11
. In this case also, the mold is melted, the wiring is short-circuited, or the magnetomotive force is reduced. The trouble caused in this case is the same as that in the above-described phenomenon (1).
When the ball bearing
27
is eventually locked as a result of breakage, slippage occurs between the pulley
26
and the belt, and the resultant frictional heat will damage and rupture the belt.
Even when the ball bearing
27
is in the normal condition, heat generation in the core
11
can happen as a result of short-circuiting of the wiring.
(3) Clutch Slippage
Further, during the operation of the electro--magnetic clutch, clutch slippage, i.e., slippage between the pulley end surface
26
d
and the armature friction plate
14
, occurs. As is well known, this slippage mitigates the shock at the time of start-up, allowing the system to start smoothly. Repetition of start-up operation leads to gradual wear of the contact surface of the armature friction plate
14
. Further, even when the gas compressor is performing normal operation, minute slippage occurs as a result of fluctuations in load in rotor rotation, momentary overload, etc.
Clutch slippage naturally involves heat generation. An abnormal increase in the slippage between the pulley end surface
26
d
and the armature friction plate
14
as a result of wear of the armature friction plate
14
, etc. causes an increase in slippage and heat generation, which can damage the contact surfaces and fuse them together. Damage to the contact surfaces will cause a further increase in clutch slippage or make them incapable of coming into contact with each other, which means the engagement of the clutch cannot be effected. Fusion of the contact surfaces makes it impossible to effect disengagement of the clutch.
It is to be noted, ho
Hirama Chihiro
Nonaka Takeshi
Adams & Wilks
Freay Charles G.
Liu Han L
Seiko Instruments Inc.
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