The present invention relates to a brushless motor with
a nut-integrated terminal connecting mechanism for inserting
and connecting a motor bus bar terminal and an ECU terminal,
and an electric power steering apparatus and a vehicle equipped
therewith. The electric power steering apparatus installed in
the vehicle is intended to apply an assist force by a motor (for
example, brushless motor) to a steering system of the vehicle
by a current command value calculated based on at least a steering
torque and is drive-controlled by an inverter comprising a bridge
circuit.
Background Art
As an apparatus equipped with a brushless motor in a
driving section, there is an electric power steering apparatus
(EPS). The electric power steering apparatus is intended to
apply a steering assist force (assist force) to a steering
mechanism of a vehicle by a rotational force of a motor, and
applies a steering assist force to a steering shaft or a rack
shaft through a transmission mechanism such as gears with a
3
driving force of a motor controlled by an electric power supplied
from an inverter. Such the electric power steering apparatus
in the related art accurately generates a torque of a steering
assist force, and thus carries out a feedback control of a motor
current. The feedback control is intended to adjust a voltage
applied to the motor to reduce a difference between a steering
assist command value (current command value) and a motor current
detected value. Adjustment of the voltage applied to the motor
is generally made by a duty adjustment in a pulse-width modulation
(PWM) control, and as the motor, a brushless motor is typically
used, which is superior in durability and maintainability and
produces less undesired sound and noise.
To illustrate and describe a general configuration of
the electric power steering apparatus in FIG.1, a column shaft
(steering shaft, handle) 2 of a steering wheel 1 is coupled to
steered wheels 8L and 8R through reduction gears 3 in a reduction
section, universal joints 4a and 4b, a pinion rack mechanism
5, tie rods 6a and 6b, and further through hub units 7a and 7b.
The column shaft 2 is provided with a torque sensor 10 that detects
a steering torque Th of the steering wheel 1 and a steering angle
sensor 14 that detects a steering angle θ, and a motor 20 that
assists a steering force of the steering wheel 1 is coupled to
the column shaft 2 through the reduction gears 3. Power is
supplied from a battery 13 to a control unit (ECU) 30 that controls
the electric power steering apparatus, and at the same time,
4
an ignition key signal is inputted into the control unit 30 through
an ignition key 11. The control unit 30 calculates a current
command value of an assist (steering assist) command based on
the steering torque Th detected by the torque sensor 10 and a
vehicle speed Vel detected by a vehicle speed sensor 12, and
controls current supplied to the motor 20 for the EPS by a voltage
control command value Vref with, for example, compensation made
for the current command value.
The steering angle sensor 14 is not necessarily required
and may not be disposed. The steering angle can also be obtained
from a rotational sensor such as a resolver connected to the
motor 20.
A Controller Area Network (CAN) 40 that sends or receives
a variety of information on the vehicle is connected to the control
unit 30, and the vehicle speed Vel can be received from the CAN
40 as well. The control unit 30 has also a Non-CAN 41 connected,
which sends or recieves, for example, communications,
analogue/digital signals, and radio waves other than the CAN
40.
An exemplary power transmission mechanism of the motor
20 of the electric power steering apparatus and an exemplary
connection of the motor 20 with the control unit (ECU) 30 are
as illustrated in FIG.2.
As illustrated in FIG.2, an output shaft 21 of the motor
20 is extended toward outside of a motor housing 22. The motor
5
housing 22 that forms a motor yoke includes a bottomed,
substantially cylindrical case body 23 that houses a motor body
including a rotor, for example, and a motor mounting section
24 mounted on an opening side of the case body 23. The motor
mounting section 24 is formed into a sheet as a whole, and via
a through-hole in a central portion thereof, the output shaft
21 is inserted outside the motor mounting section 24. The motor
mounting section 24 may be formed by a flange.
A power transmission mechanism 50 has a worm reduction
mechanism comprising a worm 51 and a worm wheel 52 and further
includes a connecting portion 53 that connects the worm reduction
mechanism and the output shaft 21. The worm 51 is formed in
a middle part of a worm shaft 51A that is coaxial with the output
shaft 21, and is engaged with the worm wheel 52. An upper
(steering wheel) side output shaft 2A of the column shaft 2 that
integrally rotates with the worm wheel 52 is connected to a shaft
center of the worm wheel 52. By the worm reduction mechanism,
the rotation of the motor 20, that is, the rotation of the output
shaft 21 is reduced and transmitted to the upper side output
shaft 2A.
An internal space of a motor mounting section 54 on a
side of the reduction mechanism is formed into a trumpet shape
so as to expand on a side of the motor 20 (opening side), and
an opening of the motor mounting section 54 is closed by bolting
the motor mounting section 54 to the motor mounting section 24
6
on the side of the motor 20. In a condition illustrated in FIG.
2 where the motor 20 is mounted on the motor mounting section
54, the connecting portion 53 and the output shaft 21 are
positioned at a shaft center of the internal space of the motor
mounting section 54. In a case where the motor mounting section
24 is formed by a flange, the motor mounting section 54 is, in
response to this, formed by a flange as well.
The motor 20, and the control unit (ECU) 30 or an ECU
substrate are separated from each other and wired by a lead wire
31, and the motor 20 is drive-controlled by the control unit
(ECU) 30 through the lead wire 31.
In this type of the electric power steering apparatus,
it is requested to reduce an overall weight and size including
the motor, and it is also strongly desired to improve
assemblability and axial precision of the motor.
A motor housing that can reduce part assembly work while
maintaining insulation among power supply members and simplifies
a power supply structure from an external power source to a motor
is disclosed in, for example, Japanese Published Unexamined Paten
Application No.2008-160988 A (Patent Document 1). A motor
insulating housing 60 disclosed in Patent Document 1 is, as
illustrated in FIGs.3 and 4, integrally formed with a housing
body 65 by an insert-molding with power supply members 61 to
64 insulated, laminated, and arranged at a distance from one
another in a through-thickness direction. It is disclosed that
7
a power connector 66 that has supply terminals 61A to 63A of
the power supply members 61 to 63 as connector terminals is
integrally molded with the housing body 65. The power supply
members 61 to 64 each are provided with a coil terminal 67
protruding outward.
The List of Prior Art Documents
Patent Documents
Patent Document 1: Japanese Published Unexamined Paten
Application No.2008-160988 A
Patent Document 2: Japanese Published Unexamined Paten
Application No.2008-220061 A
Summary of the Invention
Problems to be Solved by the Invention
However, in the motor insulating housing in Patent
Document 1, the housing body is provided only with the power
connector as the connector terminal, and the connectivity with
external devices such as the ECU has not been considered.
Downsizing of the entire motor, and improvement of the
assemblability and the axial precision have not at all been
solved.
On the other hand, a motor apparatus with a control unit
easy to mount and change and without a load or a mounting load
of the control unit applied to a connector terminal is disclosed
8
in, for example, Japanese Published Unexamined Paten Application
No. 2008-220061 A (Patent Document 2). That is, as illustrated
in FIG.5, on a motor housing 71 of a motor 70 and a housing 81
of a control unit 80, a guiding engaging section 72 and a guided
engaging section 82, which are mutually inserted and guided in
one direction and prevent movements in insertion and orthogonal
directions, are formed, respectively. By supporting the
control unit housing 81 and the motor housing 71 in the direction
perpendicular to an insertion and guiding direction or leading
them to a joining and facing position, a sensor connector 83
and a sensor circuit connector 73, and a circuit side motor winding
terminal 84 and a motor side motor winding terminal 74 are
electrically connected, and the motor housing 71 and the control
unit housing 81 are integrally fixed by a method such as screwing.
However, the motor apparatus in Patent Document 2 has
a motor bus bar and a control unit connecting terminal
non-integrated with each other, and has a large appearance
configuration. Further downsizing and simplification with
external devices such as the ECU connected is desired.
The present invention has been made in view of the above
situations, and an object thereof is to provide a brushless motor
that is smaller in appearance configuration, lighter, and easy
to manufacture, and has a terminal connecting mechanism with
an integral structure including mounting of a motor bus bar and
an ECU terminal, and an electric power steering apparatus and
9
a vehicle equipped therewith.
Means for Solving the Problems
The present invention relates to a brushless motor, the
above-described object of the present invention is achieved by
that comprising a nut-integrated terminal connecting mechanism
for inserting a motor bus bar terminal and an ECU terminal for
connecting with a bolt and nut.
The above-described object of the present invention is
more effectively achieved by that wherein the terminal connecting
mechanism is provided with a bracket holder built-in on a side
surface of a motor cover, and has a constitution being capable
of mounting and removing a terminal cover; or wherein the motor
bus bar terminal and the ECU terminal are integrated with each
other by inserting a bolt; or wherein the motor bus bar terminal
and the ECU terminal are provided with a screw hole or a circular
hole that is engaged with the bolt; or wherein the terminal
connecting mechanism has a first elongated-shape slit for
inserting the motor bus bar terminal and a second elongated-shape
slit for inserting the ECU terminal, and the first
elongated-shape slit and the second elongated-shape slit face
opposite directions; or wherein the first and second slits are
respectively elongate holes with a degree of freedom in a motor
axial direction, wide with a degree of freedom in a motor radial
direction, and capable of absorbing variations in terminal size;
10
or wherein the motor cover is made of aluminum, zinc alloy,
magnesium alloy, or sheet metal, and a rotor bearing is held
by mounting of the motor cover.
An electric power steering apparatus that is
drive-controlled by the brushless motor, and applies an assist
force to a steering system of a vehicle by a current command
value calculated based on at least a steering torque and a vehicle
equipped with the electric power steering apparatus, are
achieved.
Effects of the Invention
A brushless motor according to an embodiment of the
present invention includes a motor housing made of aluminum,
zinc alloy, or magnesium alloy, and has a nut-integrated terminal
connecting mechanism for inserting and connecting a motor bus
bar terminal and an ECU terminal with a bolt and nut. Therefore,
it is possible to reduce weight and size, improve assemblability,
and connect easily and surely to external devices such as an
ECU.
By applying the above brushless motor to an electric
power steering apparatus, a lighter, compact, and highly reliable
electric power steering apparatus can be achieved, and by
installing such the electric power steering apparatus in a
vehicle, it is possible to reduce a weight of the vehicle.
11
Brief Description of the Drawings
In the accompanying drawings:
FIG.1 is a schematic configuration view of an electric
power steering apparatus;
FIG.2 is a diagram illustrating an exemplary connecting
mechanism between a motor and a reduction section of an electric
power steering apparatus, and an exemplary connection to a
control unit (ECU);
FIG.3 is a perspective diagram illustrating an exemplary
motor insulating housing in the related art;
FIG.4 is a perspective diagram illustrating a
configuration of power supply members;
FIG.5 is a perspective view illustrating an exemplary
structure of a motor device in the related art;
FIG.6 is a perspective view illustrating an exemplary
structure of a motor housing according to an embodiment of the
present invention;
FIG.7 is an assembly development view of a brushless
motor according to an embodiment of the present invention;
FIGs.8(A) and 8(B) are assembly development views
illustrating stator and rotor assemblies built in a motor housing
of a brushless motor according to an embodiment of the present
invention, and an exemplary detailed structure of a motor cover;
FIG.9 is an assembly development view illustrating how
a cover body and a terminal connecting mechanism are mounted
12
on a motor body;
FIG.10 is an assembly development view illustrating how
a lid member is mounted on a motor body with a cover body mounted;
FIG.11 is an assembly development view illustrating how
a terminal cover is mounted on a motor body;
FIG.12 is an external perspective view of a brushless
motor according to an embodiment of the present invention;
FIG.13 is a cross-section structure view of a brushless
motor according to an embodiment of the present invention;
FIG.14 is a view illustrating an exemplary connecting
mechanism between a motor and a reduction section of an electric
power steering apparatus, and an exemplary connection to a
control unit (ECU);
FIGs. 15(A) and 15(B) are front and side views
illustrating an ECU mounted on a brushless motor according to
an embodiment of the present invention;
FIG.16 is a perspective view illustrating how an ECU
is mounted on a brushless motor (without a terminal cover)
according to an embodiment of the present invention;
FIG.17 is an upward perspective view illustrating how
an ECU is mounted on a brushless motor according to an embodiment
of the present invention;
FIG.18 is a downward perspective view illustrating how
an ECU is mounted on a brushless motor according to an embodiment
of the present invention;
13
FIGs.19(A) and 19(B) are structure views illustrating
an exemplary connection of an ECU terminal and a motor bus bar
terminal;
FIG.20 is a plane and front view illustrating an exemplary
structure of a terminal connecting mechanism according to an
embodiment of the present invention;
FIG.21 is a sectional view illustrating connected
terminals cut along a line X - X in FIG.20; and
FIG.22 is a sectional view illustrating a connecting
structure of motor bus bar terminals to ECU terminals with bolts
cut along a line Y - Y in FIG. 20.
Mode for Carrying Out the Invention
A brushless motor according to an embodiment of the
present invention comprises a motor housing made of aluminum,
zinc alloy, or magnesium alloy, and includes, on a side surface
of a motor cover, a nut-integrated terminal connecting mechanism
for inserting and connecting a motor bus bar terminal and an
ECU terminal with a bolt and nut. Thus, it is possible to reduce
weight and size of the motor, improve assemblability, and connect
easily and surely to external devices such as an ECU.
Embodiments of the present invention will be described
below with reference to the drawings. Aluminum die-casting will
be described below, but zinc alloy die-casting and magnesium
alloy die-casting are similarly applicable.
14
FIG.6 illustrates a structure of a motor housing 110
of a brushless motor 100 according to an embodiment of the present
invention. A housing body 113 is in a cylindrical shape, and
a bottom section has a planar structure including an opening
in a central portion for a motor output shaft to protrude and
doubles as a motor front cover (end plate). At an upper end
(on the drawing) of the housing body 113, an ECU mounting flange
111 is provided protruding outward, and at a lower end (on the
drawing) of the housing body 113, a motor mounting flange 112
is integrally provided protruding outward. The motor housing
110 is casted and molded integrally with the ECU mounting flange
111 and the motor mounting flange 112 by aluminum die-casting.
On this type of the motor housing 110, motor internal
parts are, as illustrated in Fig.7, built in by press fitting
or shrink fitting from one direction for assembling the brushless
motor 100. That is, firstly a stator assembly (ASSY) 120 is
inserted into the motor housing 110 for press fitting or shrink
fitting. Next, a rotor assembly (ASSY) 130 is inserted into
the stator assembly 120 fixed on the motor housing 110 for press
fitting or shrink fitting. Finally, a motor cover 140 made of
aluminum or sheet metal is mounted and fixed on the stator assembly
120 with a screw 141, for example. The stator assembly 120 and
the motor cover 140 are each provided with bearings (121, 142),
and rotate while holding shafts (131, 132) of the rotor assembly
130.
15
FIG.8(B) illustrates the stator assembly 120 and the
rotor assembly 130 built in the motor housing 110, and FIG.8(A)
illustrates details of the motor cover 140. The motor cover
140 comprises a disk-shaped cover body 140A with a terminal
connecting mechanism 150 on a side surface (periphery) and a
lid member 140B with the bearing 142 in a central portion and
a cut-notch 143 in an elongated shape in a periphery. Once a
cover member 140B is mounted on the cover body 140A, the terminal
connecting mechanism 150 protrudes just from a cut-notch 143,
and a structure of the motor cover 140 as illustrated in FIG.
7 is formed.
On an upper surface section (on the drawing) of the stator
assembly 120, motor bus bar terminals in strips 120U, 120V and
120W serving as winding terminals of a motor coil are vertically
installed facing upward. The motor bus bar terminals 120U, 120V
and 120W each are integrally provided with nuts (screw holes
120Ua, 120Va and 120Wa) threadedly engaged with bolts. In the
periphery of the cover body 140A of the motor cover 140, the
terminal connecting mechanism 150 including a cuboid insulator
(bracket holder) connected to the motor bus bar terminals 120U,
120V and 120W as well as to the external ECU terminals (210U,
210V, 210W) is provided.
FIG.9 is an assembly development view illustrating how
the cover body 140A and the terminal connecting mechanism 150
are mounted on the motor body with the stator assembly 120 and
16
the rotor assembly 130 built in the motor housing 110. The cover
body 140A has the bracket holder integrally connected, and a
terminal cover 150B can be mounted and removed. On a side surface
of the terminal cover 150B, there are circular holes or screw
holes for bolts to pass through.
FIG.10 is an assembly development view illustrating how
the cover member 140B is mounted on the motor body with the cover
body 140A mounted. The cover member 140B is mounted with the
screw 141. FIG.11 illustrates how the terminal cover 150B is
mounted on the terminal connecting mechanism 150 of the motor
body. FIG.12 is an external perspective view of the brushless
motor 100 according to an embodiment of the present invention,
with the terminal cover 150 mounted.
By this type of assembly process, the brushless motor
100 whose cross-section structure is illustrated in FIG.13 can
be obtained with a structure where the terminal connecting
mechanism 150 protrudes outward. The motor output shaft 131
protrudes from an opening of a bottom surface (front cover) of
the motor housing 110. The shafts 131 and 132 of the rotor
assembly 130 are held by the bearings 142 and 121, respectively
and are rotatable.
The brushless motor 100 according to an embodiment of
the present invention has a configuration as illustrated in
FIG.14, and is mounted on the reduction section (gear box) through
the motor mounting flange 112, and an ECU 200 is mounted on the
17
brushless motor 100 through the ECU mounting flange 111.
Mounting through the flanges 111 and 112 may be carried out with
a bolt, a nut, or a screw.
FIGs.15(A) and 15(B) illustrate in front and side
diagrams how the ECU 200 is mounted on the brushless motor 100.
The ECU 200 is coupled to the ECU mounting flange 111 through
terminal blocks 201 and 202 provided on a bottom surface side
(on the drawing) of the ECU 200, and electrically connected by
the terminal connecting mechanism 150.
FIGs.16 to 18 illustrate how the ECU 200 is mounted on
the motor 100. At ends of the bottom surface of the ECU 200,
the ECU terminals 210U, 210V and 210W and ECU mounting posts
201 and 202 are vertically installed . In mounting the ECU 200
on the motor 100, the ECU mounting posts 201 and 202 are engaged
with engaging holes of the motor cover 140, and the ECU terminals
210U, 210V and 210W are inserted into predetermined positions
of the terminal connecting mechanism 150 for engagement.
A connecting relation between the ECU terminals 210U,
210V and 210W and the motor bus bar terminals 120U, 120V and
120W is as illustrated in FIGs.19(A) and 19(B). FIG.19(A) is
an example where the nuts are connected outside the motor bus
bar terminals 120U, 120V and 120W, and FIG.19(B) is an example
where the nuts are connected inside the motor bus bar terminals
120U, 120V and 120W. In either case, the motor bus bar terminals
are connected with bolts made of conductive materials across
18
the ECU terminals with screw holes or circular holes through
nuts. As a result, the ECU terminals 210U, 210V and 210W and
the motor bus bar terminals 120U, 120V and 120W are electrically
and mechanically connected to each other.
Next, other examples of a structure of the terminal
connecting mechanism 150 and connection of the terminals will
be described in detail with reference to FIGs.20 and 21.
The terminal connecting mechanism 150 is insulating and
cuboid-shaped (bracket holder), and provided with identically
shaped nut holes 151U (inner diameter R), 151V (inner diameter
R) and 151W (inner diameter R) laterally threaded for three layers.
The inner diameter R is the same as the inner diameter of the
screw holes 120Ua, 120Va and 120Wa provided to the motor bus
bar terminals 120U, 120V and 120W. Rectangular motor terminal
engaging grooves 152U, 152V and 152W, which are each engaged
with the motor bus bar terminals 120U, 120V and 120W inserted
from below, and rectangular ECU terminal engaging grooves 153U,
153V and 153W, which are each engaged with the three-layer ECU
terminals inserted from above, are provided so as to be
perpendicular to the nut holes 151U, 151V and 151W, respectively,
in a vertical direction. The motor terminal engaging grooves
152U, 152V and 152W have the same shape with a width of LD and
a length of Ld. The ECU terminal engaging grooves 153U, 153V
and 153W have the same shape with a width of LU and a length
of Lu. Depths (heights) traverse the nut holes 151U, 151V and
19
151W.
The width LD and the length Ld of the motor terminal
engaging grooves 152U, 152V and 152W each exceed the size of
the motor bus bar terminals 120U, 120V and 120W so as to absorb
variations in dimeter of the terminals. The width LU and the
length Lu of the ECU terminal engaging grooves 153U, 153V and
153W each exceed the size of the ECU terminals 210U, 210V and
210W so as to absorb variations in dimeter of the terminals.
Thus, it is possible to smoothly carry out both the engagement
of the motor bus bar terminals 120U, 120V and 120W with the motor
terminal engaging grooves 152U, 152V and 152W, respectively and
the engagement of the ECU terminals 210U, 210V and 210W with
the ECU terminal engaging grooves 153U, 153V and 153W,
respectively.
The motor bus bar terminals 120U, 120V and 120W are
inserted from below into the motor terminal engaging grooves
152U, 152V and 152W, respectively, and the ECU terminals 210U,
210V and 210W are inserted from above into the ECU terminal
engaging grooves 153U, 153V and 153W, respectively. Then, as
illustrated in FIG.22, firstly the motor bus bar terminals 120U,
120V and 120W are threadedly engaged with bolts 154U, 154V and
154W made of conductive materials, respectively. The bolts are
further fastened, and tips of the bolts 154U, 154V and 154W are
brought into contact with the ECU terminals 210U, 210V and 210W,
respectively, and fixed. Consequently, the ECU terminals 210U,
20
210V and 210W and the motor bus bar terminals 120U, 120V and
120W can be electrically connected and mechanically fixed,
respectively. The ECU 200 and the brushless motor 100 can have
a lightweight structure and be compactly integrated with each
other.
In the above embodiment, the motor terminal engaging
grooves 152U, 152V and 152W are provided on a near side of bolt
insertion and the ECU terminal engaging grooves 153U, 153V and
153W are provided in a rear of bolt insertion, but the ECU terminal
engaging grooves 153U, 153V and 153W may be provided on the near
side and the motor terminal engaging grooves 152U, 152V and 152W
may be provided in the rear. In this case, the ECU terminals
210U, 210V, and 210W each are provided with screw holes that
threadedly engage with bolts.
In either embodiment, screw holes that threadedly engage
with bolts are provided to the motor bus bar terminals 120U,
120V and 120W or the ECU terminals 210U, 210V and 210W, but it
is possible to provide screw holes with identical inner diameters
to both of them and to have bolts penetrate through the motor
bus bar terminals 120U, 120V and 120W and the ECU terminals 210U,
210V and 210W and connected thereto.
Explanation of Reference Numerals
1 handle
2 column shaft (steering shaft, handle shaft)
21
10 torque sensor
12 vehicle speed sensor
14 steering angle sensor
20 motor
21 rotational sensor
30, 200 control unit (ECU)
40 CAN
100 blushless motor
110 motor housing
111 ECU mounting flange
112 motor mounting flange
120 stator assembly (ASSY)
130 rotor assembly (ASSY)
140 motor cover
150 motor connecting mechanism

we claims
1. A brushless motor comprising a nut-integrated terminal
connecting mechanism for inserting a motor bus bar terminal and
an ECU terminal for connecting with a bolt and nut.
2. The brushless motor according to Claim 1, wherein said
terminal connecting mechanism is provided with a bracket holder
built-in on a side surface of a motor cover, and has a constitution
being capable of mounting and removing a terminal cover.
3. The brushless motor according to Claim 1 or 2, wherein
said motor bus bar terminal and said ECU terminal are integrated
with each other by inserting a bolt.
4. The brushless motor according to Claim 3, wherein said
motor bus bar terminal and said ECU terminal are provided with
a screw hole or a circular hole that is engaged with said bolt.
5. The brushless motor according to any one of Claims 1
to 4, wherein said terminal connecting mechanism has a first
elongated-shape slit for inserting said motor bus bar terminal
and a second elongated-shape slit for inserting said ECU terminal,
and said first elongated-shape slit and said second
elongated-shape slit face opposite directions.
We Claim:
23
6. The brushless motor according to Claim 5, wherein said
first and second slits are respectively elongate holes with a
degree of freedom in a motor axial direction, wide with a degree
of freedom in a motor radial direction, and capable of absorbing
variations in terminal size.
7. The brushless motor according to any one of Claims 1
to 6, wherein said motor cover is made of aluminum, zinc alloy,
magnesium alloy, or sheet metal, and a rotor bearing is held
by mounting of said motor cover.
8. An electric power steering apparatus that is
drive-controlled by said brushless motor according to any one
of Claims 1 to 7, and applies an assist force to a steering system
of a vehicle by a current command value calculated based on at
least a steering torque.
9. A vehicle equipped with said electric power steering
apparatus according to Claim 8 by inserting a bolt.