FORM 2
THE PATENTS ACT, 1970
(39 of 1970)
&
THE PATENTS RULES, 2003
COMPLETE SPECIFICATION
[See section 10, Rule 13]
DRIVE DEVICE
MITSUBISHI ELECTRIC CORPORATION A CORPORATION ORGANISED AND
EXISTING UNDER THE LAWS OF JAPAN, WHOSE ADDRESS IS 7-3,
MARUNOUCHI 2-CHOME, CHIYODA-KU, TOKYO 1008310, JAPAN
THE FOLLOWING SPECIFICATION PARTICULARLY DESCRIBES THE
INVENTION AND THE MANNER IN WHICH IT IS TO BE PERFORMED.
2
[DESCRIPTION]
[Technical Field]
[0001]
The present disclosure relates to a drive device.
5 [Background Art]
[0002]
The drive device described in Patent Document 1 includes two boards facing each
other in an axial direction of a rotating shaft of a motor. The two boards include a first
board close to the motor in the axial direction and a second board far from the motor in the
10 axial direction. A plurality of holes are formed in each of the first board and the second
board. The first board and the second board are electrically connected by a plurality of
connection pins press-fitted into the plurality of holes.
[Citation List]
[Patent Document]
15 [0003]
[Patent Document 1]
PCT International Publication No. WO 2018/123880
[Summary of Invention]
[PROBLEM TO BE SOLVED BY THE INVENTION]
20 [0004]
For example, there are cases in which a drive device used in an electric power
steering device (for example, see Patent Document 1) has a connector connected to a board.
The connector has a role of drawing battery power, a torque sensor signal, a vehicle
communication signal, and the like, which are used to control rotation of the motor, from
25 the outside of the drive device into the inside to supply power and signals to the board.
3
[0005]
In a drive device having a connector, a configuration in which the connector and
the second board are connected, and furthermore, the second board and the first board are
connected may be employed. In this case, power and the like transmitted from the outside
5 of the drive device to the connector are supplied to the first board via the second board.
However, in such a configuration, a connection mechanism connecting the connector, the
first board, and the second board each other may become enlarged, and a size of the drive
device may increase.
[0006]
10 The present disclosure has been made to solve the above-described problems, and
an objective thereof is to provide a drive device in which it is possible to easily realize
reduction in size.
[MEANS TO SOLVE THE PROBLEM]
[0007]
15 A drive device according to the present disclosure is a drive device driving a motor
having a rotating shaft and includes a power board on which an inverter circuit driving the
motor is mounted, a control board on which a control circuit controlling driving of the
motor is mounted and disposed to face the power board in an axial direction of the rotating
shaft, an inter-board connector electrically connecting the inverter circuit and the control
20 circuit, and a connector assembly, in which the power board, the control board, and the
connector assembly are arranged in this order in the axial direction, and the connector
assembly includes a first connector terminal connected to the control board to transmit a
signal to the control circuit, and a second connector terminal connected to the power board
to supply power to the inverter circuit.
25
4
[EFFECTS OF THE INVENTION]
[0008]
According to the present disclosure, it is possible to provide a drive device in
which it is possible to easily realize reduction in size.
5 [Brief Description of Drawings]
[0009]
FIG. 1 is a cross-sectional view illustrating a drive device and an electric power
steering device according to embodiment 1.
FIG. 2 is a view illustrating a heat dissipation structure according to embodiment
10 1.
FIG. 3 is a cross-sectional view illustrating a drive device according to a modified
example of embodiment 1.
FIG. 4 is a view of a power board and a control board according to embodiment
1 from an axial direction.
15 FIG. 5 is a view of a power board and a control board according to embodiment
2 from an axial direction.
FIG. 6 is a view of a power board and a control board according to embodiment
3 from an axial direction.
FIG. 7 is a view illustrating a heat sink according to embodiment 4.
20 [Description of Embodiments]
[0010]
Embodiment 1.
FIG. 1 is a cross-sectional view of a drive device 1 and an electric power steering
device 100 according to embodiment 1. The electric power steering device 100 according
25 to the present embodiment includes the drive device 1 and a motor 2. The drive device 1
5
according to the present embodiment includes a power board 10, a control board 20, an
inter-board connector 40, a connector assembly 50, and a cover 70. The motor 2 has a
rotating shaft 32.
[0011]
5 In the following description, a direction in which a central axis O of the rotating
shaft 32 extends may be referred to as an axial direction Z. The axial direction Z is also
a thickness direction of the power board 10 and the control board 20. In the present
embodiment, the drive device 1 and the motor 2 are arranged in the axial direction Z. In
the axial direction Z, a direction directed to the drive device 1 from the motor 2 is referred
10 to as an upward direction, and may be expressed as a +Z direction. In the axial direction
Z, a direction directed to the motor 2 from the drive device 1 is referred to as a downward
direction, and may be expressed as a −Z direction. A view from the axial direction Z may
be referred to as a plan view. In a plan view, a direction intersecting the central axis O of
the rotating shaft 32 may be referred to as a radial direction, and a direction of revolving
15 around the central axis O may be referred to as a circumferential direction.
[0012]
As the motor 2, for example, a permanent magnet synchronous motor or the like
may be employed. The motor 2 according to the present embodiment is a three-phase
brushless motor. In the present specification, three phases of the motor 2 are represented
20 using U, V, and W. As illustrated in FIG. 1, the motor 2 according to the present
embodiment includes a motor main body 30 and a frame 34.
[0013]
The frame 34 according to the present embodiment has a bottomed cylindrical
shape that extends in the axial direction Z. The motor main body 30 is positioned inside
25 the frame 34. A rear housing 31 that covers an upper end (opening end) of the frame 34
6
is provided at an upper part of the motor main body 30. The motor main body 30 is
housed in the rear housing 31 and the frame 34. The rear housing 31 has a role of
preventing foreign object from entering the inside of the frame 34.
[0014]
5 The motor main body 30 includes the rotating shaft 32, a rotor 37, and a stator 38.
The rotating shaft 32 has an input end 32a positioned at an upper part and an output end
32b positioned at a lower part. An object to be driven (for example, a steering system of
a vehicle) is connected to the output end 32b.
[0015]
10 The rotor 37 is provided around the rotating shaft 32 and is fixed to the rotating
shaft 32. A plurality of permanent magnets (not illustrated) are disposed on an outer
circumferential surface of the rotor 37. The stator 38 is disposed on an outer
circumferential side of the rotor 37 with a gap therebetween. The stator 38 is fixed inside
the frame 34. The stator 38 has a plurality of windings 38a. In the present embodiment,
15 the plurality of windings 38a include at least one winding 38a corresponding to the U phase
of the motor 2, at least one winding 38a corresponding to the V phase, and at least one
winding 38a corresponding to the W phase.
[0016]
A first through hole 31a penetrating the rear housing 31 in the axial direction Z is
20 formed at a center portion of the rear housing 31 in a plan view. The input end 32a of the
rotating shaft 32 is inserted through the first through hole 31a. Similarly, a second
through hole 34a penetrating a bottom wall of the frame 34 in the axial direction Z is
formed at a center portion of the bottom wall of the frame 34 in a plan view. The output
end 32b of the rotating shaft 32 is inserted through the second through hole 34a. Also, a
25 first bearing 33 is provided in the first through hole 31a, and a second bearing 36 is
7
provided in the second through hole 34a. The bearings 33 and 36 support the rotating
shaft 32 in a state in which the rotating shaft 32 is smoothly rotatable. Thereby, the rotor
37 fixed to the rotating shaft 32 also is smoothly rotatable on an inner circumferential side
of the stator 38.
5 [0017]
In the present embodiment, a sensor magnet 35 is attached to the input end 32a of
the rotating shaft 32. The sensor magnet 35 includes at least one north pole and at least
one south pole. The sensor magnet 35 rotates together with the rotating shaft 32.
Therefore, a magnetic field generated by the sensor magnet 35 changes as the rotating shaft
10 32 rotates.
[0018]
The motor 2 has a plurality of terminals 301. Although not illustrated, the
terminals 301 are each electrically connected to the winding 38a of the motor 2. As
illustrated in FIG. 1, the terminals 301 protrude upward from the stator 38 and penetrate
15 the rear housing 31 in the axial direction Z. In the present embodiment, the plurality of
terminals 301 include a terminal 301u connected to the U-phase winding 38a, a terminal
301v connected to the V-phase winding 38a, and a terminal 301w connected to the Wphase winding 38a (not illustrated in FIG. 1, see FIG. 4).
[0019]
20 As the power board 10 and the control board 20, for example, a printed circuit
board made of glass epoxy may be used. Alternatively, as the boards 10 and 20, a socalled metal board in which a wiring pattern is provided on an aluminum base may be used.
However, types of the boards 10 and 20 are not limited to these, and may be changed as
appropriate as long as they enable mounting of electronic parts and making electrical
25 connections.
8
[0020]
As illustrated in FIG. 1, an inverter circuit 11 for driving the motor 2 is mounted
on the power board 10. Examples of electronic parts constituting the inverter circuit 11
include a field effect transistor (FET), a smoothing capacitor, a choke coil, and the like.
5 The field effect transistor switches a current flowing into the motor 2. The smoothing
capacitor suppresses change in voltage associated with the switching of the current. The
choke coil suppresses emission of noise to the outside of the drive device 1 and also
suppresses an inflow of noise to the inside of the drive device 1. The power board 10 is
electrically connected to the terminals 301 of the motor 2.
10 [0021]
As illustrated in FIG. 2, the drive device 1 may have a heat dissipation structure
61 in contact with both a lower surface of the power board 10 and an upper surface of the
rear housing 31. The heat dissipation structure 61 dissipates heat generated by the
electronic parts constituting the inverter circuit 11 to the rear housing 31. More
15 specifically, the heat generated by the electronic parts constituting the inverter circuit 11 is
absorbed, and furthermore, the absorbed heat is released to the rear housing 31. As the
heat dissipation structure 61, for example, heat dissipation grease may be used. If the
drive device 1 has the heat dissipation structure 61 described above, it is possible to cause
the rear housing 31 to function as a heat sink.
20 [0022]
As illustrated in FIG. 1, a power board through hole 12 penetrating the power
board 10 in the axial direction Z is formed at a center portion of the power board 10 in a
plan view. The input end 32a of the rotating shaft 32 is inserted through the power board
through hole 12. Thereby, an upper end (the input end 32a) of the rotating shaft 32 is
25 positioned above the power board 10.
9
[0023]
The control board 20 is disposed to face the power board 10 in the axial direction
Z. More specifically, the power board 10 and the control board 20 are fixed to the frame
34 via a fixing member 39 with a predetermined distance therebetween in the axial
5 direction Z. As the fixing member 39, for example, a screw may be employed, but this
may be changed as appropriate as long as it is possible to fix the fixing member 39 to the
frame 34. Also, the boards 10 and 20 may be fixed to the rear housing 31, the connector
assembly 50, or the cover 70 instead of the frame 34.
[0024]
10 In the present embodiment, the control board 20 is positioned above the power
board 10. The control board 20 has a first surface 20a and a second surface 20b
positioned on a side opposite to the first surface 20a. The first surface 20a is a surface
directed upward. The second surface 20b is a surface directed downward and facing the
power board 10.
15 [0025]
A control circuit C is mounted on the first surface 20a of the control board 20.
The control circuit C according to the present embodiment includes a microcontroller
(microcomputer) 21, an input circuit 22, and a power supply circuit 24. Also, a pre-driver
P is mounted on the first surface 20a of the control board 20 according to the present
20 embodiment. Note that, the inverter circuit 11, the control circuit C, and the pre-driver P
may be collectively referred to as an “electronic control unit (ECU)”. Also, the ECU and
the motor 2 may be collectively referred to as a “motor control unit (MCU)”.
[0026]
The pre-driver P drives the inverter circuit 11. More specifically, the pre-driver
25 (FET driver) P drives the field effect transistor (FET) included in the inverter circuit 11.
10
[0027]
The microcontroller 21 calculates a drive control of the motor 2. For example,
the microcontroller 21 calculates an amount of a drive current supplied to each of the
windings 38a of the motor 2 on the basis of a control signal acquired via the input circuit
5 22. On the basis of the calculation result, the microcontroller 21 controls switching of
the inverter circuit 11 via the pre-driver P. The pre-driver P and the inverter circuit 11
exchange signals between the control board 20 and the power board 10. The power
supply circuit 24 is a circuit that generates a power supply voltage required for an operation
of an electronic circuit such as the microcontroller 21.
10 [0028]
Although detailed illustrations are omitted, the input circuit 22 according to the
present embodiment includes a torque sensor interface circuit and a vehicle communication
interface circuit. The torque sensor interface circuit is a circuit for detecting a steering
torque of a driver in the electric power steering device 100 and acquiring information on
15 the steering torque. The vehicle communication interface circuit is a circuit for receiving
information of various types from a vehicle system. Examples of communication
standards handled by the vehicle communication interface circuit include a controller area
network (CAN), FlexRay (registered trademark), and the like. The input circuit 22
outputs acquired signals (the above-described steering torque information and information
20 of various types) to the microcontroller 21.
[0029]
Also, a rotation sensor S is mounted on the second surface 20b of the control board
20. The rotation sensor S faces the sensor magnet 35 in the axial direction Z. The
rotation sensor S detects a rotation angle of the rotating shaft 32 by detecting the magnetic
25 field generated by the sensor magnet 35. Note that, a position of the sensor magnet 35
11
may be changed as appropriate as long as it is possible to detect the magnetic field
generated by the sensor magnet 35 with high accuracy. For example, the rotation sensor
S and the sensor magnet 35 may not face each other in the axial direction Z, and the sensor
magnet 35 may be mounted on the first surface 20a of the control board 20.
5 [0030]
Note that, as illustrated in FIG. 3, the pre-driver P may be mounted on the power
board 10 instead of the control board 20. In this case, the microcontroller 21 and the predriver P exchange signals between the control board 20 and the power board 10. More
specifically, a pulse width modulation (PWM) instruction issued by the microcontroller 21
10 to the pre-driver P may be performed via a serial peripheral interface (SPI) communication.
[0031]
FIG. 4 is a view of the power board 10 and the control board 20 according to the
present embodiment from above. Note that, in FIG. 4, illustrations of the control circuit
C and pre-driver P are omitted. As illustrated in FIG. 4, at least a part of the power board
15 10 and at least a part of the control board 20 overlap each other when they are projected in
the axial direction Z. Hereinafter, a region of the power board 10 and the control board
20 in which they overlap may be referred to as an overlapping region A1. As illustrated
by the broken line in FIG. 4, the terminals 301u, 301v, and 301w of the motor 2 according
to the present embodiment are electrically connected to the overlapping region A1 of the
20 power board 10 (see also FIG. 1).
[0032]
Also, as illustrated in FIG. 4, the power board 10 has at least one (four in the
illustrated example) non-overlapping region A2 that does not overlap the control board 20
when it is projected in the axial direction Z. More specifically, in the present embodiment,
25 a size of the control board 20 is smaller than the size of the power board 10. Thereby,
12
end portions of the power board 10 are the non-overlapping region A2. Also, the control
board 20 according to the present embodiment includes a control board through hole 23
formed to penetrate the control board 20 in the axial direction Z. Thereby, a portion of
the power board 10 that overlaps the control board through hole 23 when it is projected in
5 the axial direction Z is the non-overlapping region A2.
[0033]
As illustrated in FIG. 1, the inter-board connector 40 is positioned between the
power board 10 and the control board 20 in the axial direction Z. The inter-board
connector 40 electrically connects the inverter circuit 11 and the control circuit C. As
10 illustrated by the broken line in FIG. 4, the inter-board connector 40 according to the
present embodiment is disposed to overlap the overlapping region A1 of the power board
10 and the control board 20 when it is projected in the axial direction Z. Note that, the
drive device 1 includes only one inter-board connector 40 in the illustrated example, but
the number of the inter-board connectors 40 may be changed as appropriate according to a
15 layout of the boards 10 and 20, the number of necessary signals, or the like.
[0034]
As illustrated in FIG. 1, the inter-board connector 40 according to the present
embodiment includes a male connector 41 and a female connector 42. The connectors 41
and 42 each include a housing and a plurality of terminals (not illustrated) disposed inside
20 the housing and responsible for electrical connection. The housing may be formed, for
example, of a resin in its entirety, or may be partially formed of a metal. The housing of
the male connector 41 and the housing of the female connector 42 are designed so that they
fit to each other, and terminals of the connectors 41 and 42 are electrically connected to
each other when they are fitted. The connectors 41 and 42 according to the present
25 embodiment are connectors which are able of being surface mounted on a printed circuit
13
board or the like by soldering. Note that, in the illustrated example, the male connector
41 is mounted on the power board 10 and the female connector 42 is mounted on the control
board 20, but the male connector 41 may be mounted on the control board 20 and the
female connector 42 may be mounted on the power board 10.
5 [0035]
Also, the inter-board connector 40 may be a connector having a so-called floating
structure in which the male connector 41 and the female connector 42 slide against each
other. In this case, even if mounting positions of the connectors 41 and 42 are offset with
respect to the board 10 and 20, it is possible to improve the poor fitting caused by the offset
10 and to alleviate a stress applied to the connectors 41 and 42 after the fitting.
[0036]
Note that, a configuration of the inter-board connector 40 is not limited to the
above example, and may be changed as appropriate as long as it is possible to secure an
electrical connection between the power board 10 and the control board 20 with high
15 quality. For example, a configuration in which holes of a predetermined size and a
predetermined number are provided in the boards 10 and 20 and the terminals are soldered
to the holes may be employed. Alternatively, a configuration in which a predetermined
surface mount connector is provided on each of the boards 10 and 20 and a harness or a
so-called flexible flat cable (FFC) is fitted to the surface mount connector may be
20 employed.
[0037]
The cover 70 is a topped cylindrical member. An opening end of the cover 70 is
in contact with an opening end of the frame 34. The power board 10 and the control
board 20 are housed in a space surrounded by the cover 70 and the rear housing 31.
25
14
[0038]
The connector assembly 50 according to the present embodiment is provided on
an upper wall of the cover 70. In the axial direction Z, the stator 38 of the motor 2, the
power board 10, the control board 20, and the connector assembly 50 are arranged in this
5 order.
[0039]
The connector assembly 50 is a component in which connectors, metal bus bars,
terminals, and the like, and a holding member 53 that holds them are integrally molded.
The holding member 53 is made of, for example, a resin. The connector assembly 50
10 connects a battery voltage line and a ground line required for controlling the motor 2 and
driving the motor 2 to the boards 10 and 20. Also, the connector assembly 50 connects a
signal transmission line for transmitting signals such as a torque sensor signal and a vehicle
communication signal to the boards 10 and 20. In the connector assembly 50, the abovedescribed lines may be combined into one. Alternatively, according to a design of the
15 vehicle, the battery voltage line and the ground line may be separated from the signal
transmission line to be disposed in separate connectors.
[0040]
As illustrated in FIG. 1, the connector assembly 50 according to the present
embodiment includes at least a first connector terminal 51 and a second connector terminal
20 52. The connector terminals 51 and 52 extend downward from the holding member 53.
In the present embodiment, a lower end of the second connector terminal 52 is positioned
below a lower end of the first connector terminal 51. The first connector terminal 51 is a
terminal connected to the control board 20 to transmit signals such as the torque sensor
signal and the vehicle communication signal to the control circuit C. That is, the first
25 connector terminal 51 has at least a function of connecting the above-described signal
15
transmission line to the control board 20. The second connector terminal 52 is a terminal
connected to the power board 10 to supply power to the inverter circuit 11. That is, the
second connector terminal 52 has at least a function of connecting the above-described
battery voltage line to the power board 10. Although a method of connecting the
5 terminals 51 and 52 and the respective boards 10 and 20 is not particularly limited, they
may be electrically connected by, for example, press fitting. Alternatively, the terminals
51 and 52 may be inserted into through holes formed in the respective boards 10 and 20,
and the through holes and the terminals 51 and 52 may be joined by solder. Terminals
mounted on the respective boards 10 and 20 and the terminals 51 and 52 may be connected
10 by welding.
[0041]
As illustrated in FIG. 4 and FIG. 1, the second connector terminal 52 extending
from the connector assembly 50 is inserted through the control board through hole 23 and
linearly connects the connector assembly 50 and the non-overlapping region A2 of the
15 power board 10. According to this configuration, it is possible to make a configuration
of connecting the connector assembly 50 and the power board 10 smaller compared to a
case in which, for example, the second connector terminal 52 extends to bypass the control
board 20. Note that, a notch may be formed in the control board 20 instead of the control
board through hole 23, and the second connector terminal 52 may be inserted through the
20 notch. Also, as illustrated in FIGS. 1 and 4, the first connector terminal 51 extending
from the connector assembly 50 is connected to the overlapping region A1 of the control
board 20.
[0042]
Next, an operation of the drive device 1 configured as above will be described.
25
16
[0043]
There are cases in which a drive device used in an electric power steering device
has a connector assembly connected to a board. The connector assembly has a role of
connecting a battery voltage line, a ground line, and a signal transmission line that extend
5 from the outside of the drive device to a board positioned inside the drive device. Here,
if the drive device has two boards, a power board and a control board, a configuration in
which the lines are each connected only to the control board is conceivable. In this case,
the battery voltage line and the ground line necessary for an operation of the power board
are connected to the power board via the control board. However, in such a configuration,
10 there is a likelihood that a connection mechanism that connects the connector, the power
board, and the control board will become enlarged, and this will cause an increase in size
of the drive device. Also, if the control board relays the battery voltage line and the
ground line, the control board must be designed to withstand a large amount of current
flowing through these lines, and this may cause an increase in size and cost of the control
15 board.
[0044]
In contrast, in the drive device 1 according to the present embodiment, the
connector terminals 51 and 52 extending from the connector assembly 50 are each directly
connected to the boards 10 and 20 without interposing a board or the like. Thereby, the
20 number of connection points of the inter-board connector 40 is reduced, thereby making it
easier to reduce a size of the inter-board connector 40. That is, it is easier to realize
reduction in size of the drive device 1. Also, it is possible to design the pattern mounted
on the control board 20 with a low current circuit, and it is possible to simplify a
configuration of the control board 20.
25
17
[0045]
As described above, the drive device 1 according to the present embodiment
configured to drive the motor 2 having the rotating shaft 32 includes the power board 10
on which the inverter circuit 11 driving the motor 2 is mounted, the control board 20 on
5 which the control circuit C controlling driving of the motor 2 is mounted and disposed to
face the power board 10 in the axial direction Z, the inter-board connector 40 electrically
connecting the inverter circuit 11 and the control circuit C, and the connector assembly 50,
in which the power board 10, the control board 20, and the connector assembly 50 are
arranged in this order in the axial direction Z, and the connector assembly 50 includes the
10 first connector terminal 51 connected to the control board 20 to transmit a signal to the
control circuit C, and the second connector terminal 52 connected to the control board 20
to supply power to the inverter circuit 11.
[0046]
According to this configuration, the connector terminals 51 and 52 are each
15 directly connected to the boards 10 and 20. Therefore, it is possible to reduce a
configuration of connecting the connector assembly 50, the power board 10, and the
control board 20 in size. Thereby, it is easier to realize reduction in size of the drive
device 1.
[0047]
20 Also, the power board 10 has at least one non-overlapping region A2 that does not
overlap the control board 20 when it is projected in the axial direction Z, and the second
connector terminal 52 is connected to the non-overlapping region A2 of the power board
10. According to this configuration, it is possible to linearly connect the connector
assembly 50 and the power board 10 using the second connector terminal 52. Thereby, it
25 is possible to make a configuration of connecting the connector assembly 50 and the power
18
board 10 smaller compared to a case in which, for example, the second connector terminal
52 extends to bypass the control board 20.
[0048]
Also, the power board 10 and the control board 20 have at least one overlapping
5 region A1 in which they overlap each other when they are projected in the axial direction
Z, and the inter-board connector 40 is disposed to overlap the overlapping region A1 when
it is projected in the axial direction Z. Due to this configuration, it is easier to realize
reduction in diameter of the drive device 1.
[0049]
10 Also, the terminal 301 of the motor 2 is connected to the overlapping region A1
of the power board 10. With this configuration, it is easier to realize reduction in diameter
of the drive device 1.
[0050]
Also, the rotating shaft 32 has the input end 32a at which the sensor magnet 35 is
15 provided, the power board through hole (through hole) 12 through which the input end 32a
of the rotating shaft 32 is inserted is formed in the power board 10, and the rotation sensor
S detecting a magnetic field generated by the sensor magnet 35 is mounted on the control
board 20. With this configuration, it is possible to detect a rotation angle of the rotating
shaft 32 using the rotation sensor S. Also, when the rotation sensor S is mounted on the
20 control board 20, it is possible to keep a large amount of current flowing in the inverter
circuit 11 mounted on the power board 10 away from the rotation sensor S. Thereby, it
is possible to reduce an influence of the magnetic field generated by the large amount of
current on the rotation sensor S, and it is possible to improve a detection accuracy of the
rotation sensor S. Also, since the rotation sensor S and the control circuit C are mounted
25 on the same board, it is possible to reduce the number of terminals of the inter-board
19
connector 40.
[0051]
Also, the drive device 1 according to the present embodiment further includes the
pre-driver P which drives the inverter circuit 11, the pre-driver P is mounted on the control
5 board 20, and the pre-driver P and the inverter circuit 11 exchange signals between the
control board 20 and the power board 10. With this configuration, it is possible to reduce
the number of connection signals between the power board 10 and the control board 20.
[0052]
Also, the pre-driver P may be mounted on the power board 10, the control circuit
10 C may include the microcontroller 21 which calculates a drive control of the motor 2, and
the microcontroller 21 and the pre-driver P may exchange signals between the control
board 20 and the power board 10. Even with this configuration, it is possible to reduce
the number of connection signals between the power board 10 and the control board 20 by
using, for example, the SPI communication.
15 [0053]
Also, the drive device 1 according to the present embodiment may further include
the heat dissipation structure 61 dissipating heat generated by the electronic parts
constituting the inverter circuit 11 to the rear housing 31 which houses the motor 2.
According to this configuration, it is possible to efficiently dissipate heat generated by the
20 electronic parts constituting the inverter circuit 11.
[0054]
Embodiment 2.
Next, embodiment 2 will be described, but basic configurations are the same as
those of embodiment 1. Therefore, components which are the same are denoted by the
25 same reference signs, description thereof will be omitted, and only different points will be
20
described.
[0055]
As illustrated in FIG. 5, in the present embodiment, a terminal 301 of a motor
main body 30 is connected to a non-overlapping region A2 of a power board 10. More
5 specifically, a control board 20 according to the present embodiment includes a notch 24
formed to open at an outer circumferential edge of the control board 20. Also, since the
notch 24 is formed in the control board 20, a portion of the power board 10 that overlaps
the notch 24 in an axial direction Z is the non-overlapping region A2. The terminal 301
according to the present embodiment is connected to the non-overlapping region A2.
10 When the terminal 301 is connected to the non-overlapping region A2 of the power board
10, it is possible to suppress an adverse effect that heat generation of the terminal 301
exerts on the control circuit C mounted on the control board 20.
[0056]
Embodiment 3.
15 Next, embodiment 3 will be described, but basic configurations are the same as
those of embodiment 1. Therefore, components which are the same are denoted by the
same reference signs, description thereof will be omitted, and only different points will be
described.
[0057]
20 As illustrated in FIG. 6, in the present embodiment, a control board through hole
23 is not formed in a control board 20. Even in this case, when a size of the control board
20 is made sufficiently smaller than the size of a power board 10, it is possible to connect
a second connector terminal 52 and the power board 10 to each other in a non-overlapping
region A2 positioned at an end portion of the power board 10. Also, as illustrated in the
25 illustrated example, the connector terminals 51 and 52 may constitute connectors 51C and
21
52C, respectively. Even with this configuration, since it is possible to linearly connect a
connector assembly 50 and the power board 10 using the second connector terminal 52, it
is possible to suppress connection parts becoming enlarged.
[0058]
5 Embodiment 4.
Next, embodiment 4 will be described, but basic configurations are the same as
those of embodiment 1. Therefore, components which are the same are denoted by the
same reference signs, description thereof will be omitted, and only different points will be
described.
10 [0059]
As illustrated in FIG. 7, a drive device 1 according to the present embodiment
includes a heat sink 60. The heat sink 60 is positioned between a power board 10 and a
control board 20 in an axial direction Z. Also, a second heat dissipation structure 61A in
contact with both a lower surface of the heat sink 60 and an upper surface of the power
15 board 10 is provided between the heat sink 60 and the power board 10. The heat sink 60
according to the present embodiment absorbs heat generated by electronic parts
constituting an inverter circuit 11 via the second heat dissipation structure 61A.
According to this configuration, since the heat generated by the electronic parts
constituting the inverter circuit 11 is dissipated to both a rear housing 31 and the heat sink
20 60, it is possible to improve a heat dissipation efficiency. However, when the drive device
1 includes the heat sink 60, a heat dissipation structure 61 positioned between the power
board 10 and the rear housing 31 may not be provided. That is, the heat generated by the
electronic parts constituting the inverter circuit 11 may be dissipated only to the heat sink
60.
25
22
[0060]
Note that, the modified examples described in each embodiment may be
combined with each other, or the configuration according to each embodiment may be
modified or omitted as appropriate.
5 [0061]
For example, a so-called one-system drive device 1 and motor 2 has been
described in the above-described embodiment, but the present disclosure may also be
applied to a so-called two-system drive device 1 and motor 2. That is, the drive device 1
may have two sets of the control circuits C and two sets of the inverter circuits 11, and the
10 motor 2 may have two sets of the terminals 301 (301u, 301v, and 301w). When the two
sets of the inverter circuits 11 are configured to drive the motor 2 independently of each
other, redundancy is secured. In this case, the two sets of the control circuits C may be
mounted on the control board 20 to be divided point-symmetrically or line-symmetrically.
Similarly, the two sets of the inverter circuits 11 may be mounted on the power board 10
15 to be divided point-symmetrically or line-symmetrically. The two sets of the terminals
301 (301u, 301v, and 301w), connectors, and the like may be disposed point-symmetrically
or line-symmetrically.
[Reference Signs List]
[0062]
20 1 Drive device
2 Motor
10 Power board
11 Inverter circuit
Power board through hole (through hole)
25 20 Control board
23
21 Microcontroller
C Control circuit
P Pre-driver
S Rotation sensor
5 31 Rear housing
32 Rotating shaft
32a Input end
35 Sensor magnet
40 Inter-board connector
10 50 Connector assembly
51 First connector terminal
52 Second connector terminal
60 Heat sink
61 Heat dissipation structure
15 A1 Overlapping region
A2 Non-overlapping region
Z Axial direction

WE CLAIMS:
[Claim 1]
A drive device driving a motor having a rotating shaft, comprising:
a power board on which an inverter circuit driving the motor is mounted;
5 a control board on which a control circuit controlling driving of the motor is
mounted and disposed to face the power board in an axial direction of the rotating shaft;
an inter-board connector electrically connecting the inverter circuit and the control
circuit; and
a connector assembly, wherein
10 the power board, the control board, and the connector assembly are arranged in
this order in the axial direction, and
the connector assembly includes:
a first connector terminal connected to the control board to transmit a
signal to the control circuit; and
15 a second connector terminal connected to the power board to supply
power to the inverter circuit.
[Claim 2]
The drive device according to claim 1, wherein
the power board has at least one non-overlapping region which does not overlap
20 the control board when it is projected in the axial direction, and
the second connector terminal is connected to the non-overlapping region of the
power board.
[Claim 3]
The drive device according to claim 1 or 2, wherein
25 the control board and the power board have at least one overlapping region in
25
which they overlap each other when they are projected in the axial direction, and
the inter-board connector is disposed to overlap the overlapping region when it is
projected in the axial direction.
[Claim 4]
5 The drive device according to any one of claims 1 to 3, wherein
the control board and the power board have at least one overlapping region in
which they overlap each other when they are projected in the axial direction, and
the terminal of the motor is connected to the overlapping region of the power
board.
10 [Claim 5]
The drive device according to any one of claims 1 to 3, wherein
the power board has at least one non-overlapping region which does not overlap
the control board when it is projected in the axial direction, and
the terminal of the motor is connected to the non-overlapping region of the power
15 board.
[Claim 6]
The drive device according to any one of claims 1 to 5, wherein
the rotating shaft has an input end at which a sensor magnet is provided,
a through hole through which the input end of the rotating shaft is inserted is
20 formed in the power board, and
a rotation sensor detecting a magnetic field generated by the sensor magnet is
mounted on the control board.
[Claim 7]
The drive device according to any one of claims 1 to 6, further comprising a pre25 driver which drives the inverter circuit, wherein
26
the pre-driver is mounted on the control board, and
the pre-driver and the inverter circuit exchange a signal between the control board
and the power board.
[Claim 8]
5 The drive device according to any one of claims 1 to 6, further comprising a predriver which drives the inverter circuit, wherein
the pre-driver is mounted on the power board,
the control circuit includes a microcontroller which calculates a drive control of
the motor, and
10 the microcontroller and the pre-driver exchange a signal between the control
board and the power board.
[Claim 9]
The drive device according to any one of claims 1 to 8, further comprising a heat
dissipation structure dissipating heat generated by electronic parts constituting the inverter
15 circuit to a rear housing which houses the motor.
[Claim 10]
The drive device according to any one of claims 1 to 9, further comprising a heat
sink provided between the power board and the control board in the axial direction and
absorbing heat generated by electronic parts constituting the inverter circuit.