Electrical generator or motor structure – Dynamoelectric – Rotary
Reexamination Certificate
2001-06-28
2004-03-02
Tamai, Karl (Department: 2834)
Electrical generator or motor structure
Dynamoelectric
Rotary
C310S208000, C310S043000
Reexamination Certificate
active
06700234
ABSTRACT:
This application is based on Application No. 2000-327223, filed in Japan on Oct. 26, 2000, the contents of which are hereby incorporated by reference.
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an electromagnetic device such as a stepping motor, a solenoid valve, or the like, used in an automotive continuously variable transmission, for example.
2. Description of the Related Art
FIG. 4
is an external view of a permanent-magnet stepping motor,
FIG. 5
is a cross section taken along line V—V in
FIG. 4
,
FIG. 6
is a cross section taken along line VI—VI in
FIG. 5
,
FIG. 7
is a cross section taken along line VII—VII in
FIG. 5
, and
FIG. 8
is a partial exploded perspective of the stepping motor in FIG.
5
.
In the figures, a permanent-magnet (PM) stepping motor
1
, which is immersed and used in an oil, includes: an outer casing
2
made of a resin; a tubular housing
12
made of a resin which is linked to the outer casing
2
; a motor main body
3
disposed inside the outer casing
2
; a shaft
4
functioning as a moveable shaft rotated by the motor main body
3
; and a conversion mechanism
31
for converting rotation of the shaft
4
into rectilinear motion. Moreover, the outer casing
2
and the housing
12
constitute a cover.
The motor main body
3
includes a pair of stators
5
secured to the outer casing
2
, and a rotor
6
secured to the shaft
4
. The stators
5
have: coils
7
which are each constructed by winding a conducting wire in which an electrically-insulating layer is formed on a copper wire surface; coil terminals
8
led out from the coil
7
; connector terminals
9
connected to the coil terminals
8
; and an external connector
25
connected to the connector terminals
9
. The rotor
6
has a bush
10
secured to the shaft
4
, and a circumferentially-magnetized hollow cylindrical permanent magnet
11
fitted over and secured to the bush
10
.
The housing
12
is fastened to the outer casing
2
by a plurality of screws
12
A extending parallel to the shaft
4
. A circular interfitting aperture
2
a
is formed in the outer casing
2
, and an interfitting portion
12
a
for inserting into the interfitting aperture
2
a
is formed on the housing
12
. As shown in
FIG. 6
, three positioning projections
12
b
, which protrude radially and come into contact with an inner circumferential surface of the interfitting aperture
2
a
, are formed on an outer circumferential surface of the interfitting portion
12
a
. Furthermore, an annular groove
12
c
is formed in a joining surface of the housing
12
, where the housing
12
joins the outer casing
2
.
A housing communicating aperture
12
d
communicating between internal and external portions of the housing
12
is disposed in a side surface portion of the housing
12
. A filter
13
for catching contaminants contained in the oil is disposed in the housing communicating aperture
12
d
. The shaft
4
is rotatably held by a casing bearing
14
and a housing bearing
15
. The housing bearing
15
, which is secured inside the housing
12
, is a rubber-seal type.
A rod
16
reciprocated in an axial direction of the shaft
4
by rotation of the shaft
4
is disposed at a tip portion of the housing
12
. A base-end portion of the rod
16
is inserted inside the housing
12
, and a tip portion of the rod
16
protrudes from the tip portion of the housing
12
. A rod communicating aperture
16
a
communicating between the internal portion of the housing
12
and an internal portion of the rod
16
is formed in the rod
16
. A sleeve
17
for guiding rectilinear motion of the rod
16
, an oil seal
18
for preventing penetration of contaminants from an outer circumferential portion of the rod
16
, and a ring-shaped stopper
19
for regulating progression of the rod
16
are each secured to an inner circumferential surface of the tip portion of the housing
12
.
The conversion mechanism
31
includes a thread portion
4
a
, a guide member
20
made of a resin which is formed in the base-end portion of the rod
16
and is engaged with the thread portion
4
a
, and a stopper
21
made of a metal which is secured to the shaft
4
and regulates regression of the rod
16
. Stopper surfaces
20
b
and
21
a
which are perpendicular to the direction of rotation of the shaft
4
are formed on the guide member
20
and the stopper
21
, respectively. As shown in
FIG. 7
a rotation-regulating projection portion
20
a
which protrudes radially and regulates rotation of the rod
16
is formed on an outer circumferential portion of the guide member
20
. Consequently, the guide member
20
is displaced in an axial direction of the shaft
4
by rotation of the shaft
4
. An operating member
22
made of a resin is mounted to the tip portion of the rod
16
.
A construction of each of the stators
5
will now be explained in detail with reference to
FIGS. 9
to
12
.
As shown in
FIG. 10
, the coils
7
are each constructed by winding a conducting wire
50
, shown in
FIG. 9
, formed by coating a copper wire
51
with an electrically-insulating layer
52
composed of a polyimide resin, which is a thermoplastic resin, onto a bobbin
53
composed of nylon, which is a thermoplastic resin, for a predetermined number of winds. Then, end portions of the conducting wire
50
of each coil
7
are connected to the coil terminals
8
mounted to the bobbin
53
. Furthermore, as shown in
FIG. 11
, the coil
7
wound onto the bobbin
53
is embedded in an outer molding
54
composed of nylon, which is a thermoplastic resin. In addition, as shown in
FIG. 12
, cores
55
made of iron are disposed so as to surround the coil
7
, completing the construction of the stator
5
.
The stepping motor
1
constructed in this manner is mounted to an automobile continuously variable transmission, for example, and the operating member
22
attached to the tip portion of the rod
16
is engaged with a link
40
which opens and closes a transmission control valve in the continuously variable transmission.
When an electric current is passed through the external connector
25
, the coils
7
are magnetized, rotating the rotor
6
and the shaft
4
together. The guide member
20
is engaged in the thread portion
4
a
on the shaft
4
, and since rotation of the guide member
20
is regulated, rotation of the shaft
4
is converted into rectilinear motion of the guide member
20
and the rod
16
.
The transmission control valve is opened and closed through the link
40
by reciprocation of the rod
16
, ultimately changing the rotational velocity ratio between the drive shaft and the engine shaft.
The conventional stepping motor
1
is mounted to an automobile continuously variable transmission, for example, and is entirely immersed in the oil, which contains sulfur and organosulfur compounds. Furthermore, the coils
7
of the stators
5
are covered by the bobbins
53
and the outer moldings
54
which are composed of the thermoplastic resin, and the conducting wires
50
of the coils
7
are constructed by coating the copper wire
51
with the electrically-insulating layer
52
, which is composed of the thermoplastic resin. For that reason, the sulfur and the organosulfur compounds in the oil permeate the bobbins
53
and the outer moldings
54
, and in addition permeate the electrically-insulating layer
52
, reaching the copper wire
51
. As a result, chemical reactions occur at the surface of the copper wire
51
and organosulfur compounds are formed on the surface of the copper wire
51
, giving rise to a state of decreased adhesive strength of the electrically-insulating layer
52
to the copper wire
51
.
One problem has been that in this state, the electrically-insulating layer
52
may be breached due to interference between adjacent conducting wires
50
caused by repeated thermal expansion and thermal contraction due to the heat history of the conducting wires
50
themselves, leading to wire breakage or short circuiting between the conducting wires
50
caused by elution of copper due to electric p
Hasegawa Shiro
Hashimoto Naoya
Miyaoku Teruo
Ohta Hirohisa
Ozawa Hiromasa
Perez Guillermo
Tamai Karl
LandOfFree
Electromagnetic device does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Electromagnetic device, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Electromagnetic device will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-3225574