Electrical generator or motor structure – Dynamoelectric – Rotary
Reexamination Certificate
2000-03-31
2002-08-06
Mullins, Burton S. (Department: 2834)
Electrical generator or motor structure
Dynamoelectric
Rotary
C310S071000, C310S07500D, C180S400000
Reexamination Certificate
active
06429553
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to an electric motor having a control drive means and particularly to a technique effectively applied to an electric power steering apparatus for vehicles. And, the present invention, in particular, relates to a technique effectively applied to an electric power steering apparatus used in a rack-and-pinion type steering apparatus.
To assist steering torque of a vehicle, so-called power steering apparatuses are used in many vehicles in recent years, and various power steering apparatuses, such as a hydraulic type, an electric type, and the like have been proposed. Of these power steering apparatuses, a known electric power steering apparatus applied to a rack-and-pinion type of steering apparatus will be one called a rack assist type which obtains a steering assist force by an electric motor provided coaxially on the rack shaft. This type uses an electric motor, which incorporates a field magnetic device, an armature, and the like in a cylindrical yoke, and the steering torque is assisted by this electric motor.
FIG. 19
is a view which explains an example of the rack assist type of power steering apparatus using this kind of electric motor. In the electric type of power steering apparatus shown in
FIG. 19
, an electric motor
52
is provided to be coaxial relative to the rack shaft
51
and steering assist force generated by the electric motor
52
is transmitted to the rack shaft
51
through a ball screw mechanism
53
. Further, the steering wheel is rotated by the steering assist force together with a manual handling force, thereby reducing steering burdens of a driver.
The rack shaft
51
is connected with steering wheels by tie rods, knuckle arms, and the like provided at both ends thereof. The rack shaft
51
is connected by a rack-and-pinion manner to a steering shaft
54
connected to a steering handle or the like and reciprocates in left and right direction in
FIG. 19
by steering of the driver. The electric motor
52
is constructed such that a cylindrical armature shaft
56
and a field magnetic device
57
are coaxially inserted in a cylindrical yoke
55
, and an electric power is supplied from a power supply section
58
. The field magnetic device
57
comprises a magnetic
59
attached on the inner circumferential portion of the yoke
55
and an armature core
60
attached on the outer circumferential portion of the armature shaft
56
. The turning force generated by the electric motor
52
is transmitted as reciprocal motion in the axial direction to the rack shaft
51
through a ball screw mechanism
53
provided at the left end of the armature shaft
56
in FIG.
19
, and thus, the steering force is assisted.
The power supply section
58
is provided with a brush
61
and a commutator
62
which makes slidable contact with the brush, and the electric power is supplied to the armature portion of the electric motor
52
through these components. The brush
61
is contained and held in a brush holder
63
and is pressed against the commutator with a predetermined pressure by a spring member not shown. A terminal plate
65
is welded to an end of a pigtail
64
of the brush
61
. The terminal plate
65
penetrates the housing
66
and projects to the outside. A coupler
67
is attached to the projected terminal plate
65
. Thus, the terminal for power supply is formed.
Meanwhile, there has been a proposed apparatus for incorporating control elements such as FETs and the like in the power supply section and for forming integrally a power steering apparatus and a control device section thereof. For example, in Japanese Patent Application Laid Open No. 6-255504, a power steering apparatus is described. In this apparatus, a hollow chamber is formed at the connecting portion where a housing containing a brushless motor and a housing holding a handle shaft are connected with each other, and a power circuit unit which contains FETs and circuit boards in the hollow chamber is provided. Further, Japanese Patent Application Laid-Open No. 8-26125 describes a power steering apparatus in which FETs and boards are contained in a gear box housing where a steering shaft is held and connected with a motor yoke.
In the electronic motor used in the apparatus shown in
FIG. 19
or the above example, the power supply section thereof is provided at the connecting portion where an opening edge side of the yoke, the housing (or yoke) of the electric motor side, and the housing of the steering shaft side are connected to each other. It is therefore possible to incorporate relatively easily a brush, a control circuit, and the like in the vicinity of the opening edge of the yoke or a dividing surface. Even in this kind of power steering apparatus using an electric motor, the control circuit or the like can be incorporated so as to be inserted in the vicinity of the dividing surface. Therefore, integration of the apparatus body with the control drive section can be achieved with ease, and there is no problem caused in assembling operation.
However, in an electric motor which uses a cylindrical yoke provided with a side wall at one end thereof and is provided with a power supply section in the side wall side, the power supply section is not situated at the opening portion. Therefore, the control drive section cannot be simply integrated like the above example. That is, if a control drive section is integrally incorporated into this kind of electric motor, various components must be assembled deep into the yoke from the opening side thereof. This results in a drawback in assembling operation.
Also, there is such a type of a power steering apparatus that the housing and yoke in the steering shaft side are formed integrally, a power supply section, an armature, a field magnetic device, and the like are assembled therein, and these components are coupled with another housing containing a ball screw mechanism. The power supply section cannot be situated near a driving portion therebetween. Therefore, the control drive section cannot be integrated easily like the above example. In this type of power steering apparatus, an end side of the yoke of the housing in the steering shaft side is formed in a cylindrical shape which is closed except a rack shaft insertion portion, and the power supply section is provided at a deepest portion of a closed end. Consequently, also in this kind of power steering apparatus, if the control drive section is integrally incorporated, various components must be assembled deep in the housing. So, there are difficulties in assembling operation. Therefore, it is not possible to easily adopt a structure that a space for a control section is formed at a part of the housing like the foregoing example and control elements and boards are assembled in the space. Improvement has hence been demanded in this respect.
The present invention therefore has an object of integrally providing a control drive section with the apparatus body in this kind of electric motor without reducing efficiency of the assembling operation. Also, another object of the present invention is to integrally provide a control drive section of an electric power steering apparatus with the apparatus body without reducing efficiency of the assembling operation.
The above and other related objects and novelty features of the invention will be apparent from reading of the following specification and the accompanying drawings.
SUMMARY OF THE INVENTION
An electric motor according to the present invention comprises a cylindrical housing having a side wall at one end portion thereof and is characterized in that a control drive means for controlling and driving the electric motor is provided at an end portion in a side of the side wall inside the housing or on an outer surface of the side wall. As a result of this, even in an electric motor having an electric motor which is provided deep in the housing, the control drive means can be integrally provided with the electric motor without hindering the assembling operation.
In this case, the control drive means m
Aoki Susumu
Mochizuki Wataru
Ogawa Hideyuki
Taniguchi Yoshiaki
Lam Thanh
McCormick Paulding & Huber LLP
Mitsuba Corporation
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