192 clutches and power-stop control – Clutches – Operators
Reexamination Certificate
2000-04-13
2003-05-06
Rodríguez, Saúl (Department: 3681)
192 clutches and power-stop control
Clutches
Operators
C335S220000
Reexamination Certificate
active
06557686
ABSTRACT:
FIELD OF THE INVENTION
The subject invention relates to an electro-magnetic actuator having a shortened magnetic flux flow loop.
BACKGROUND OF THE INVENTION
Many modern vehicles include an engine and an electro-magnetic actuator for controlling a viscous fluid clutch associated with an engine cooling fan. In general operation, the clutch is designed to couple and decouple the fan and the engine. When the clutch is actuated, a rotary force is transmitted from the engine through the clutch to the fan. In this manner, the cooling fan is mechanically driven by the engine. Typically, the rotary force is produced by a water pump pulley within the engine. When the clutch is deactuated, the fan is decoupled from the engine. As such, no rotary force is transmitted from the engine to the fan. The electro-magnetic actuator is used to actuate and deactuate the clutch.
FIG. 1
is a cross-sectional side view of a prior art electro-magnetic actuator
10
attached to a known type of viscous fluid clutch
12
. The prior art actuator
10
includes a housing
14
, a rotary shaft or core
16
, a nut
18
, a non-magnetic stainless steel bushing
20
, a bearing
22
, an electrical coil
24
, and a ferromagnetic can
26
. The rotary shaft
16
, includes a first end portion
28
disposed outside the housing
14
and a second end portion
30
disposed inside the housing
14
. The entire shaft
16
is adapted to rotate or spin in relation to the housing
14
.
The nut
18
includes an inner peripheral surface
32
, an outer peripheral surface
34
, and a fastening means
36
, such as a thread. The fastening means
36
is adapted to attach the actuator
10
to the clutch
12
. When attached, the nut
18
spins with the clutch
12
. The stainless steel bushing
20
is adapted to couple the first end portion
28
of the shaft
16
and the inner peripheral surface
32
of the nut
18
. When coupled, the shaft
16
, the bushing
20
,and the nut
18
form a interface surface
38
which spins with the clutch
12
.
Conventionally, the actuator
10
is threaded into a mounting and interface port
40
in the clutch
12
. In this arrangement, the interface surface
38
is disposed adjacent to a spring-loaded armature plate
42
located inside the clutch
12
. The interface surface
38
is spaced from the armature plate
42
to form an air gap
44
.
The bearing
22
is disposed around the second end portion
30
of the shaft
16
. The bearing
22
is adapted to rotatably support the shaft
16
. The electrical coil
24
is disposed around the shaft
16
between the nut
18
and the bearing
22
. The electrical coil
24
is adapted to receive electrical current and produce magnetic flux.
The ferromagnetic can
26
is disposed around the shaft
16
. The can
26
has a peripheral surface
46
extending between the shaft
16
and the outer peripheral surface
34
of the nut
18
. The peripheral surface
46
of the can
26
establishes a path for magnetic flux flow between the shaft
16
and the outer peripheral surface
34
of the nut
18
. The peripheral surface
46
of the can
26
is shaped to encase both the electrical coil
24
and the bearing
22
inside the can
26
.
The electrical coil
24
forms a ring around the entire shaft
16
inside the can
26
. When power is applied to the actuator
10
, electrical current flows through the coil
24
producing magnetic flux. The magnetic flux flows in a loop
48
, hereinafter referred to as a magnetic flux flow loop, which circles radially about the cross-sectional center point of the coil
24
. The magnetic flux consists of magnetic lines of force which collectively constitute a magnetic field. The magnetic field is formed in a toroidal or doughnut like shape around the axis of the shaft
16
.
The magnetic flux flow loop
48
is illustrated in FIG.
1
. The magnetic flux flow loop
48
extends from the first end portion
28
of the shaft
16
through the length of the shaft
16
to the second end portion
30
of the shaft
16
, from the second end portion
30
of the shaft
16
along the peripheral surface
46
of the can
26
around or outside both the bearing
22
and the electrical coil
24
to the outer peripheral surface
34
of the nut
18
, from the outer peripheral surface
34
of the nut
18
through the nut
18
to the inner peripheral surface
32
of the nut
18
, and between the inner peripheral surface
32
of the nut
18
and the first end portion
28
of the shaft
16
along an arch-shaped airborne path portion
50
. The airborne path portion
50
of the magnetic flux flow loop
48
arches outwardly from the actuator
10
around the non-magnetic bushing
20
.
When power is applied to the actuator
10
, the airborne path portion
50
of the magnetic flux flow loop
48
applies a magnetic force across the air gap
44
onto the armature plate
42
located inside the clutch
12
. The magnetic force pulls the armature plate
42
inward, from a spring-loaded closed position to an open position, reducing the air gap
44
between the armature plate
42
and the interface surface
38
. In the open position, the armature plate
42
permits fluid flow and coupling within the clutch
12
. In this manner, the actuator
10
actuates the clutch
12
.
When power is not applied to the actuator
10
, the armature plate
42
returns to the spring-loaded off position. In the spring-loaded off position, the armature plate
42
restricts fluid flow and coupling within the clutch
12
. In this manner, the clutch
12
is deactuated.
Although the prior art actuator
10
effectively actuates and deactuates the clutch
12
, it has several shortcomings. For one, the magnetic flux flow loop
48
about the electrical coil
24
is relatively long, thereby reducing the strength of the clutch actuation force and overall electrical efficiency of the actuator
10
. For another, the bearing is a separate component disposed inside the can thus requiring associated labor and assembly time. Accordingly, it would be desirable to provide an electro-magnetic actuator which overcomes the shortcomings of the prior art.
SUMMARY OF INVENTION
The present invention is an electro-magnetic actuator having a shortened magnetic flux flow loop. The actuator includes a shaft having a first end portion and a second end portion and a nut having an inner peripheral surface and an outer peripheral surface. The inner peripheral surface of the nut is coupled with the first end portion of the shaft. A bearing is disposed around the second end portion of the shaft for rotatably supporting the shaft. An electrical coil is disposed around the shaft between the nut and the bearing for receiving electrical current and producing magnetic flux. A ferromagnetic can is disposed around the shaft having a peripheral surface extending between the shaft and the outer peripheral surface of the nut for establishing a path for magnetic flux flow there between. The peripheral surface of the can is interposed between the electrical coil and the bearing partitioning the electrical coil inside the can and the bearing outside the can. Preferably, the bearing is a circular ball bearing assembly which is insert molded into the actuator.
The present invention provides an electro-magnetic actuator having a shorter magnetic flux flow loop, a stronger clutch actuation force, and a greater electrical efficiency than prior art actuators. Additionally, insert molding the ball bearing assembly into the actuator reduces the cost of the present invention relative to prior art actuators.
REFERENCES:
patent: 4119184 (1978-10-01), Mower et al.
patent: 4846325 (1989-07-01), Mohan
patent: 4893703 (1990-01-01), Kennedy et al.
patent: 5025906 (1991-06-01), O'Neil et al.
patent: 5511643 (1996-04-01), Brown
Budd Walter J.
Dolinshek Thomas J.
Hojnacki Steve R.
Pontiac Coil
Rodríguez Saúl
Young & Basile
LandOfFree
Electro-magnetic actuator having a shortened magnetic flux... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Electro-magnetic actuator having a shortened magnetic flux..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Electro-magnetic actuator having a shortened magnetic flux... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3045695