U.S. patent application number 13/980449 was filed with the patent office on 2013-11-07 for motor.
This patent application is currently assigned to Hitachi, Ltd.. The applicant listed for this patent is Itsuro Sawada, Atsushi Yokoyama. Invention is credited to Itsuro Sawada, Atsushi Yokoyama.
Application Number | 20130294888 13/980449 |
Document ID | / |
Family ID | 46720241 |
Filed Date | 2013-11-07 |
United States Patent
Application |
20130294888 |
Kind Code |
A1 |
Yokoyama; Atsushi ; et
al. |
November 7, 2013 |
MOTOR
Abstract
A motor is provided which can detect a rotor temperature with
high precision with a simple configuration not taking an influence
on a temperature caused by circulation of a cooling oil into
account. In a motor including a rotor, a stator arranged around the
rotor, and a temperature sensor, the rotor includes an oil
reservoir unit that reserves an oil on a rotating shaft line in an
interior thereof, and the temperature sensor detects a temperature
of the oil reserved in the oil reservoir unit.
Inventors: |
Yokoyama; Atsushi;
(Hitachiota, JP) ; Sawada; Itsuro; (Hitachinaka,
JP) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Yokoyama; Atsushi
Sawada; Itsuro |
Hitachiota
Hitachinaka |
|
JP
JP |
|
|
Assignee: |
Hitachi, Ltd.
Tokyo
JP
|
Family ID: |
46720241 |
Appl. No.: |
13/980449 |
Filed: |
February 21, 2011 |
PCT Filed: |
February 21, 2011 |
PCT NO: |
PCT/JP2011/053638 |
371 Date: |
July 18, 2013 |
Current U.S.
Class: |
415/47 |
Current CPC
Class: |
F01D 19/02 20130101;
H02K 9/19 20130101; H02K 11/25 20160101; H02K 1/32 20130101 |
Class at
Publication: |
415/47 |
International
Class: |
F01D 19/02 20060101
F01D019/02 |
Claims
1. A motor comprising: a rotor, a stator arranged around the rotor,
and a temperature sensor, wherein the rotor includes an oil
reservoir unit that reserves an oil on a rotating shaft line in an
interior thereof, and wherein the temperature sensor detects a
temperature of the oil reserved in the oil reservoir unit.
2. The motor according to claim 1, wherein the temperature sensor
has one end fitted to a motor cover of the motor, and the other end
inserted into the oil reservoir unit on the rotating shaft line of
the rotor, and contacting with the oil.
3. The motor according to claim 1, wherein the temperature sensor
includes a housing having a cylindrical portion and a bottom
portion, and a temperature detection unit arranged on an inner
peripheral surface of the cylindrical portion.
4. The motor according to claim 2, wherein an oil seal that
prevents the oil reserved in the oil reservoir unit from being
leaked out of the rotor is arranged between the temperature sensor
and the rotor.
5. The motor according to claim 3, wherein the temperature
detection unit is arranged on the inner peripheral surface of the
cylindrical portion on a lower side of the motor.
6. The motor according to claim 1, wherein the motor includes an
oil storage chamber, the rotor includes an oil supply path on the
rotating shaft line in an interior thereof, and the oil storage
chamber and the oil reservoir unit communicate with each other
through the oil supply path.
7. The motor according to claim 6, wherein the oil supply path
includes an oil circulation path having at least an oil inflow path
and an oil outflow path.
8. The motor according to claim 7, wherein the rotor includes a
continuous hole that communicates between the oil circulation path
and the oil reservoir unit, and the continuous hole is pierced in
the rotating shaft line.
9. The motor according to claim 1, wherein the motor includes a
temperature calculation unit for calculating a rotor temperature
and/or a temperature of a magnet embedded in the rotor according to
an oil temperature detected by the temperature detection sensor.
Description
TECHNICAL FIELD
[0001] The present invention relates to a motor, and more
particularly to a motor that can detect a rotor temperature with
high precision.
BACKGROUND ART
[0002] In recent years, in a field of transport equipments such as
an electric vehicle, a hybrid vehicle, and an electric train, the
development of a motor that can achieve a high efficiency and a
high torque with a reduction in size and weight has been rapidly
advanced from the viewpoints of a reduction in an environmental
load.
[0003] As an example of this motor, there is an IPM motor (interior
permanent magnet motor) in which a magnet is embedded in an
interior of a rotor. The IPM motor can use both of a reluctance
torque caused by magnetization of the rotor and a torque caused by
magnetization of the magnet, and the magnet is embedded in the
interior of the rotor formed of a silicon steel plate. As a result,
the magnet does not fall out to the external by a centrifugal force
of the motor even during rotation of the motor, and an excellent
safety is obtained. For that reason, a current phase is controlled
to enable high torque operation and operation at an extensive
speed.
[0004] Incidentally, in general, there has been known that in an
induction motor using no magnet, when the motor is driven by an
inverter circuit, an iron loss of a rotor is converted into a heat,
a temperature of the rotor rises, and a motor torque is lessened.
In particular, in the case of the IPM motor in which the magnet is
embedded in the interior of the motor, a magnet temperature also
rises in association with the temperature rise of the rotor. When
the magnet temperature exceeds a limit temperature, the magnet is
demagnetized to further lessen the motor torque. Also, there arises
such a problem that even if the magnet thus demagnetized is cooled
to return the magnet temperature to the limit temperature, a
desired motor torque is not obtained.
[0005] Under the circumstances, in order to suppress a reduction in
the torque of the motor attributable to the rise of the rotor
temperature and a reduction in the efficiency caused by the torque
reduction, there arises an urgent issue in this field to precisely
measure the rotor temperature within the motor, and also the
temperature of the magnet when the magnet is embedded in the
rotor.
[0006] However, because the rotor per se rotates during driving of
the motor, it is extremely difficult to measure the temperature of
the rotor or the magnet within the rotor, for example, by cable. It
is also conceivable to measure the temperature of the rotor, etc.
by a non-contact thermometer such as a thermography. However, this
makes the device configuration complicated and upsized, resulting
in an increase in the manufacturing costs of the motor.
[0007] Under the circumstances, a technique of measuring the rotor
temperature or the magnet temperature with the use of a cooling oil
that is reflexed within the motor in order to cool the rotor is
disclosed in PTL 1 and PTL 2. PTL 1 discloses a rotor temperature
estimation method of measuring an inflow temperature of the cooling
oil before being supplied to the rotor and an outflow temperature
of the cooling oil after the rotor has been cooled, in reflexing
the cooling oil within the motor, and estimating the rotor
temperature on the basis of the inflow temperature, the outflow
temperature, a thermal resistance of the rotor which has been
obtained in advance, and a weight corresponding to an operating
status of the rotor.
[0008] Also, PTL 2 discloses a magnet temperature estimation device
and a method therefor, which estimate the magnet temperature by
directly measuring the temperature of the cooling oil after the
magnet has been cooled, which is emitted by a centrifugal force
when rotationally driving the rotor. [0009] PTL 1: JP-A-2000-23421
[0010] PTL 2: JP-A-2008-178243
SUMMARY OF INVENTION
Technical Problem
[0011] In the rotor temperature estimation method disclosed in PTL
1, because the rotor temperature or the magnetic temperature is
estimated with the use of an arithmetic expression defined in
advance, the operation of constructing a variable for the
arithmetic operation is required. Also, in order to make an
estimated value of the rotor temperature or the magnetic
temperature, which is calculated according to the above arithmetic
expression, approximate to a real temperature of the rotor or the
magnet, there is a need to detect the states of the cooling oil
such as the flow rate or flow velocity of the cooling oil, the
inflow temperature of the cooling oil into the rotor, or the
outflow temperature of the cooling oil from the rotor, with high
precision.
[0012] Also, in the magnet temperature estimation device and the
method therefor disclosed in PTL 2, the cooling oil temperature to
be measured is changed by the flow rate of the cooling oil or the
inflow temperature of the cooling oil into the rotor. For that
reason, the rotor temperature or the magnet temperature to be
estimated cannot be made to approximate to the real temperature
without a complicated calculation taking the flow rate and the
inflow temperature into account.
[0013] Thus, in both of the rotor temperature estimation methods
disclosed in PTL 1 and PTL 2, there is a need to accurately grasp a
circulation state of the cooling oil subjected to forced convection
such as the flow velocity or the flow rate, and the temperature
change when the cooling oil passes through the rotor. However, it
is difficult to detect the state of the cooling oil with
elaboration. Therefore, the rotor temperature or the magnet
temperature cannot be measured with high precision.
[0014] The present invention has been made in view of the above
problems, and an object of the present invention is to provide a
motor that can detect the rotor temperature with high precision
with a simple configuration not taking an influence on the
temperature caused by the circulation of the cooling oil into
account.
Solution to Problem
[0015] In order to solve the above problem, according to the
present invention, there is provided a motor, including a rotor, a
stator arranged around the rotor, and a temperature sensor, in
which the rotor includes an oil reservoir unit that reserves an oil
on a rotating shaft line in an interior thereof, and the
temperature sensor detects a temperature of the oil reserved in the
oil reservoir unit.
[0016] According to the above configuration, since the rotor
includes the oil reservoir unit for reserving the oil on the
rotating shaft line, the reserved oil temperature can be detected
by the temperature sensor, and a rotor temperature can be detected
according to the oil temperature. As a result, the rotor
temperature can be detected with high precision not taking an
influence of an inflow temperature, the flow rate, and the flow
velocity of the oil into account.
Advantageous Effects of Invention
[0017] As understandable from the above description, according to
the present invention, the rotor temperature can be easily detected
with high precision by measuring a temperature of a fluid reserved
in the reservoir unit within the rotor. In particular, in the case
of a magnet motor in which a magnet is embedded within the rotor, a
magnet temperature can be also calculated with high precision with
the use of the detected rotor temperature, and the demagnetization
of the magnet attributable to the temperature rise can be
effectively suppressed.
[0018] The other problems, configurations and advantageous effects
will become apparent from the following description of the
embodiments.
BRIEF DESCRIPTION OF DRAWINGS
[0019] FIG. 1 is a vertical cross-sectional view illustrating a
motor according to a first embodiment of the present invention.
[0020] FIG. 2 is an enlarged diagram of an oil reservoir unit
according to the first embodiment illustrated in FIG. 1, in which
(a) shows a vertical cross-sectional view illustrating a
relationship between an oil and a temperature sensor in a motor
stop state, (b) shows a view taken along an arrow A-A of (a), (c)
shows a vertical cross-sectional view illustrating a relationship
between the oil and the temperature sensor in a motor drive state,
and (d) shows a view taken along an arrow C-C of (c).
[0021] FIG. 3 is a, vertical cross-sectional view illustrating a
motor according to a second embodiment of the present
invention.
[0022] FIG. 4 is a vertical cross-sectional view illustrating a
motor according to a third embodiment of the present invention.
[0023] FIG. 5 is an enlarged diagram of an oil reservoir unit
according to a third embodiment of the present invention, in which
(a) shows a vertical cross-sectional view illustrating a
relationship of an oil, a temperature sensor, and a continuous hole
in a motor stop state, and (b) is a vertical cross-sectional view
illustrating a relationship of the oil, the temperature sensor, and
the continuous hole in a motor drive state.
[0024] FIG. 6 is a vertical cross-sectional view illustrating a
motor according to a fourth embodiment of the present
invention.
LIST OF REFERENCE SIGNS
[0025] 1, rotor [0026] 2, stator [0027] 3, coil [0028] 4, oil
reservoir unit [0029] 6, oil seal [0030] 7, step [0031] 8, 19, oil
supply path [0032] 9, magnet [0033] 10, gear [0034] 11, oil inflow
path [0035] 12, inflow port [0036] 13, oil outflow path [0037] 14,
outflow port [0038] 15, coupling path [0039] 16, continuous hole
[0040] 17, partition [0041] 18, oil circulation path [0042] 19A,
oil exhaust path [0043] 20, 60, motor cover [0044] 21, outside cap
[0045] 22, inside cap [0046] 23, 63, bearing [0047] 24, inverter
circuit [0048] 25, 65, rotating angle sensor [0049] 26, rotation
control means [0050] 27, temperature calculation unit [0051] 28,
substrate [0052] 29, 68, opening portion [0053] 30, temperature
sensor [0054] 31, cylindrical portion [0055] 32, bottom portion
[0056] 33, jaw portion [0057] 34, corner portion [0058] 35, housing
[0059] 36, temperature detection unit [0060] 40, reducer [0061] 41,
housing [0062] 42, oil storage chamber [0063] 43, gear [0064] 44,
shaft [0065] 45, bearing [0066] 46, oil seal [0067] 47, oil pool
[0068] 48, oil supply path, [0069] 51, motor case [0070] 52, water
jacket [0071] 53, bearing [0072] 54, step [0073] 61, 62, oil seal
[0074] 64, oil storage unit [0075] 69, oil exhaust path [0076] 100,
200, 300, 400, motor [0077] A, continuous hole inner diameter
[0078] D, oil reservoir unit inner diameter [0079] d, temperature
sensor outer diameter [0080] L, rotor rotating shaft line [0081] P,
PA, oil
DESCRIPTION OF EMBODIMENTS
[0082] Hereinafter, a motor according to embodiments of the present
invention will described with reference to the drawings.
First Embodiment
[0083] FIG. 1 illustrates a motor according to a first embodiment
of the present invention. In the first embodiment, a configuration
in which a magnet is embedded in an interior of a rotor will be
described. However, the same configuration can be applied to a
configuration in which no magnet is embedded in the interior of the
rotor.
[0084] A motor 100 shown in the figure includes a rotor 1 and a
stator 2 arranged around an outer peripheral surface lA of the
rotor 1, and a coil 3 is wound on the stator 2 in multiple turns,
and the coil 3 is energized so that the rotor 1 is rotationally
driven about a rotating shaft line L as a rotating center. A magnet
9 is embedded in an interior of the rotor 1 along the outer
peripheral surface 1A thereof.
[0085] Also, a motor case 51 internally having a water jacket 52
which circulates a cooling water is disposed outside of the stator
2. With this configuration, an outer peripheral surface of the
rotor 1 and the stator 2 can be protected from an external
environment, and a heat radiated from the rotor 1 can be absorbed
by the internal cooling water to cool the rotor 1 or the stator 2.
Also, a motor cover 20 including an outside cap 21 and an inside
cap 22 is disposed on one end side of the rotor 1 in the rotating
shaft line L direction. A substrate 28 is disposed on a surface 22A
of the inside cap 22 of the motor cover 20 facing the outside cap
21, and an inverter circuit 24 having a temperature calculation
unit 27 that calculates a rotor temperature and a magnet
temperature is placed on the substrate 28. The inverter circuit 24
further includes a rotation control unit 26 so as to control a
rotating speed of the rotor 1 on the basis of a signal from a
rotating angle sensor 25 disposed on the rotor 1 side of the inside
cap 22 in order to detect the rotation of the rotor 1 and the rotor
temperature and the magnet temperature calculated by the
temperature calculation unit 27. Also, bearings 53 and 23 are
disposed between the motor case 51 and the rotor 1, and between the
inside cap 22 and the rotor 1, respectively, so that the rotor 1
can rotate relatively with respect to the motor case 51 and the
inside cap 22.
[0086] An oil reservoir unit 4 for reserving an oil P on the
rotating shaft line L of the rotor 1 is disposed on an end of the
motor cover 20 side of the rotor 1. In this example, the oil
reservoir unit 4 is formed into substantially a cylindrical shape
coaxial with the rotating shaft line L of the rotor 1. Also, an
opening portion 29 is formed substantially in the center (on the
rotating shaft line L of the rotor 1) of the inside cap 22 of the
motor cover 20. A temperature sensor 30 is inserted through the
opening portion 29 along the rotating shaft line L, and fitted to
the inside cap 22 by a jaw portion 33. The jaw portion 33 of the
temperature sensor 30 is fixedly engaged with an outer peripheral
portion of the opening portion 29 of the inside cap 22 so that the
temperature sensor 30 is fixed to the inside cap 22. In this
example, the temperature sensor 30 is formed into the substantially
cylindrical shape coaxial with the rotating shaft line L of the
rotor 1, as with the oil reservoir unit 4. As described above, the
temperature sensor 30 is inserted along the rotating shaft line L,
and fitted to the inside cap 22 by the jaw portion 33, as a result
of which the entire temperature sensor 30 is inserted into the oil
reservoir unit 4 along the rotating shaft line L without contact
with the rotor 1. An outer diameter of the temperature sensor 30 is
set to be relatively smaller than an inner diameter of the oil
reservoir unit 4. As described above, the temperature sensor 30
formed into the substantially cylindrical shape on the rotating
shaft line L of the rotor 1 is arranged without contact with an
inner surface of the oil reservoir unit 4 having the substantially
cylindrical shape. As a result, even if the rotor 1 rotates around
the temperature sensor 30 in a state where the temperature sensor
30 is fixed to the motor cover 20, an inner peripheral surface of
the oil reservoir unit 4 and an outer peripheral surface of the
temperature sensor 30 do not contact with each other, and are not
worn away.
[0087] Also, the oil P of a given amount is reserved in the oil
reservoir unit 4, and the temperature sensor 30 and the oil P come
indirect contact with each other at the time of stopping or driving
the motor, and a heat is transmitted between the temperature sensor
30 and the rotor 1 through the oil P. That is, the heat radiated
from the rotor 1 is transmitted to the oil P, and further
transmitted to the temperature sensor 30 so that the temperature of
the oil P is measured by the temperature sensor 30 to detect the
temperature of the rotor 1. An oil seal 6 is interposed between the
rotor 1 and the temperature sensor 30, and as shown in the figure,
the temperature sensor 30 is fixed to the motor cover 20. Even if
the rotor 1 rotates relatively with respect to the temperature
sensor 30, the oil seal 6 can prevent the oil P within the oil
reservoir unit 4 from being leaked out of the rotor 1.
[0088] The temperature sensor 30 is roughly configured by a housing
35 including a cylindrical portion 31 extending in the rotating
shaft line L direction of the rotor 1 and a bottom portion 32 that
closes one end of the cylindrical portion 31, and a temperature
detection portion 36. The temperature detection portion 36 is
fitted to the inner peripheral surface of the cylindrical portion
31, and an end of the housing 35 opposite to the bottom portion 32
is opened, and the temperature detection portion 36 is joined to
the inverter circuit 24 through an opening portion of the opposite
end by a conductive wire not shown. As a result, a detected signal
of the temperature of the oil P, which is measured by the
temperature detection portion 36, is transmitted to the temperature
calculation unit 27 and the rotation control unit 26 within the
inverter circuit 24, and used for calculation of the temperatures
of the rotor 1 and the magnet 9, or for control of the rotating
speed of the rotor 1. The temperature sensor 30 is formed into the
cylindrical shape, and the temperature detection portion 36 is
arranged inside thereof so that the temperature detection portion
36 and the oil P to be measured can be arranged in proximity to
each other, and the temperature measurement with a high response
and higher elaboration is enabled. The temperature detection
portion 36 may be, for example, a thermistor or a thermocouple.
[0089] A reducer 40 is disposed on a side of the motor case 51
opposite to the motor cover 20 side. The reducer 40 is roughly
configured by a housing 41 that demarcates an oil storage chamber
42, and a gear 43 that is disposed on a shaft 44 arranged within
the housing 41. A gear 10 disposed on the end of the rotor 1 and
the gear 43 are meshed with each other so that the rotating speed
of the rotor 1 is reduced and transmitted to the shaft 44. A
bearing 45 is disposed between the housing 41 and the shaft 44 so
that the shaft 44 can rotate relatively with respect to the housing
41.
[0090] Subsequently, a procedure of assembling the motor 100
according to the first embodiment will be described.
[0091] First, the rotor 1 in which the magnet 9 is embedded along
the outer peripheral surface 1A, and the stator 2 on which the coil
3 is wound are prepared. Also, the motor case 51 having the water
jacket 52, and the bearing 53 fitted to the end opposite to the
side to which the motor cover 20 is fitted is prepared. Then, the
stator 2 is inserted into the motor case 51 from the side at which
the motor cover 20 is fitted. In this situation, a step 54 formed
on the inner peripheral surface of the motor case 51 is abutted
against a corner of the stator 2 to position the stator 2 relative
to the motor case 51. Then, the rotor 1 is inserted into the motor
case 51 until a step 7 formed on the rotor 1 is abutted against the
bearing 53.
[0092] Also, the motor cover 20 is prepared in another process
different from the above process. That is, the substrate 28 is
fitted to one surface 22A of the inside cap 22 of the motor cover
20, and the inverter circuit 24 having the temperature calculation
unit 27 and the rotation control unit 26 is placed on the substrate
28. Also, the rotation sensor 25 and the bearing 23 are arranged on
the other surface opposite to the one surface 22A of the inside cap
22. The opening portion 29 is formed substantially in the center of
the inside cap 22, and the temperature sensor 30 is inserted
through the opening portion 29 in the rotating shaft line L
direction of the rotor 1, and fitted to the inside cap 22 by the
jaw portion 33 on the end thereof. The rotation sensor 25 and the
temperature sensor 30 are connected to the inverter circuit 24 by a
conductive wire not shown. The outside cap 21 is fitted to the
inside cap 22 so as to cover the one surface 22A of the inside cap
22, that is, the inverter circuit 24 to form the motor cover 20. As
a method of fitting the outside cap 21 and the inside cap 22, there
are a fitting method using a fitting claw, a fitting method using a
fastening member such as a bolt or a screw, and a fitting method
due to adhesion by using an adhesive.
[0093] After the motor cover 20 is thus installed, and the oil P of
the desired amount is poured into the oil reservoir unit 4 of the
rotor 1, the motor cover 20 is fitted to the motor case 51 along
the rotating shaft line L so that a part of the temperature sensor
30 of the motor cover 20 is inserted into the oil reservoir unit 4.
A corner 34 of a leading end of the temperature sensor 30 is
tapered so that the temperature sensor 30 can be guided into the
oil reservoir unit 4. Also, the oil seal 6 is arranged between the
rotor 1 and the temperature sensor 30 on an end of the oil
reservoir unit 4 of the rotor 1 so that the oil P is not leaked out
of the rotor 1 from the oil reservoir unit 4 after the temperature
sensor 30 is inserted into the oil reservoir unit 4.
[0094] FIG. 2 illustrates a relationship between the oil P poured
into the oil reservoir unit 4 and the temperature sensor 30
according to the first embodiment. FIG. 2(a) illustrates a motor
stop state, FIG. 2(b) is a view taken along an arrow A-A of FIG.
2(a), FIG. 2(c) illustrates a motor drive state, and FIG. 2(d) is a
view taken along an arrow C-C of FIG. 2(c). In general, when the
motor 100 of the first embodiment is applied to a vehicle, as
illustrated in FIGS. 1 and 2, the motor 100 is fitted to the
vehicle so that the rotating shaft line L of the rotor 1 becomes
horizontal.
[0095] As illustrated in FIG. 2(a), when the motor 100 is arranged
in the vehicle so that the rotating shaft line L of the rotor 1
becomes horizontal, the oil P pools in a lower portion of the oil
reservoir unit 4 in the stop state of the motor 100. Even in the
stop state of the motor 100, in order to detect the temperature of
the rotor 1 by the temperature sensor 30, as illustrated in FIG.
2(b), there is a need to reserve the oil P in the oil reservoir
unit 4 by the amount of oil P required to transmit the heat between
the temperature sensor 30 and the rotor 1, that is, so that a space
between a lower portion of the oil reservoir unit 4 of the rotor 1
and a lower portion (temperature detection portion 36) of the
temperature sensor 30 is filled with the oil P.
[0096] As illustrated in FIG. 2(c), when the motor 100 is driven,
the oil P in the oil reservoir unit 4 is thrust outside of the oil
reservoir unit 4 in the radial direction by its centrifugal force,
and a (heat transmission) layer of the oil P is formed on the inner
peripheral surface of the oil reservoir unit 4. In order to detect
the temperature of the rotor 1 by the temperature sensor 30 with
high precision in the above drive state of the motor 100, as
illustrated in FIG. 2(d), there is a need to reserve the oil P by
the amount as large as the space between the rotor 1 and the
temperature sensor 30 is filled with the layer of the oil P, that
is, by the amount of .pi.(D.sup.2-d.sup.2)L1/4 or more. In this
expression, D is an inner diameter of the oil reservoir unit 4, d
is an outer diameter of the temperature sensor 30, and L1 is a
length of the oil reservoir unit 4 in the rotating shaft line L.
When the rotating speed of the rotor 1 is relatively low in the
drive state of the motor 100, because the oil P in the oil
reservoir unit 4 pools on the lower portion, the amount of oil P
reserved in the oil reservoir unit 4 can be reduced.
[0097] As described above, the oil P is thrust outside in the
radial direction at the time of driving the motor 100. Therefore,
even in this case, in order to measure the temperature of the oil P
by the temperature detection portion 36 of the temperature sensor
30 with a high response and elaboration, as illustrated in FIG. 2,
it is preferable that the temperature detection portion 36 is
fitted to the outside in the radial direction with respect to the
rotating shaft line L of the rotor 1, that is, on the inner
peripheral surface of the cylindrical portion 31 of the temperature
sensor 30.
[0098] In the above first embodiment, the temperature detection
portion 36 of the temperature sensor 30 is fitted to particularly
the lower side of the inner peripheral surface of the cylindrical
portion 31. With the above configuration, even when the motor 100
is arranged so that the rotating shaft line L of the rotor 1
becomes horizontal, and in the stop state of the motor 100 as
illustrated in FIG. 2(a), the heat is always transmitted between
the inner peripheral surface of a portion to which the temperature
detection portion 36 is fitted, and the rotor 1 through the oil P,
and the temperature of the oil P can be measured by the temperature
detection portion 36 with the high response. Also, even when the
rotating speed of the rotor 1 is low, because the oil P within the
oil reservoir unit 4 mainly pools in a vertically lower portion, it
is preferable that the temperature detection portion 36 is fitted
to the lower side of the inner peripheral surface of the
cylindrical portion 31 of the temperature sensor 30. That is, the
temperature detection portion 36 is fitted to the vertically lower
side of the inner peripheral surface of the cylindrical portion 31
of the temperature sensor 30 as in the first embodiment. As a
result, the heat of the rotor 1 can be efficiently transmitted to
the temperature detection portion 36 regardless of the rotating
speed of the rotor 1, and the heat transmission characteristic from
the rotor 1 can be stabilized.
[0099] When the rotating shaft line L of the rotor 1 becomes
vertical, that is, the motor cover 20 is arranged on a vertically
upper portion, the oil P pools at the end of the oil reservoir unit
4 opposite to the motor cover 20 side at the time of stopping the
motor 100. For that reason, in order to transmit the heat between
the rotor 1 and the temperature sensor 30, there is a need to
reserve the oil P within the oil reservoir unit 4 by the amount of
.pi.D.sup.2 (L1-L2)/4 or more. In this expression, L2 is a length
of the temperature sensor 30 in the oil reservoir unit 4 in the
rotating shaft line L direction. On the other hand, when the rotor
1 rotates at a relatively high speed, as in FIG. 2(c) and (d), the
oil P is thrust outside in the radial direction of the oil
reservoir unit, it is preferable to reserve the oil P by the amount
of .pi.(D.sup.2-d.sup.2)L1/4 or more. Also, when the motor cover 20
is arranged on the vertically upper portion as described, in order
to measure the temperature of the oil P with a high response,
particularly at the time of stopping the motor 100, the temperature
detection portion 36 can be disposed on the inner surface of the
bottom portion 32 of the temperature sensor 30.
[0100] Also, when the overall oil reservoir unit 4 is filled with
the oil P, a contact area of the temperature detection unit 30 and
the oil P can increase, and the oil P temperature can be more
efficiently measured by the temperature detection portion 36. Also,
when the overall oil reservoir unit 4 is filled with the oil P,
even if the rotating shaft line L of the rotor 1 is arranged to be
horizontal or vertical, the temperature of the oil P can be
measured with high precision regardless of the mounting position of
the temperature detection portion 36 and the rotating speed of the
rotor 1.
[0101] Thus, in the first embodiment, in measuring the temperature
of the oil to which the heat is transmitted from the rotor 1 by the
temperature detection portion 36, when the temperature of the oil P
reserved in the oil reservoir unit 4 is measured, the temperature
of the oil P can be measured without taking the influence of the
inflow temperature, the flow rate, and the flow velocity of the oil
P into account. On the basis of the measurement result, the
temperature of the rotor 1 can be detected with high precision. In
detecting the temperature of the rotor 1, calibration information
on the temperature of the oil P and the temperature of the rotor 1
which are obtained in advance may be used. Also, the temperature of
the magnet 9 which is embedded in the rotor 1 whose temperature can
generally become higher than those temperatures can be calculated
with high precision by using the temperature calculation unit 27 on
the basis of the drive state (rotor rotating speed and torque) of
the motor, an energy loss (iron loss) corresponding to the drive
state, a heat resistance and a heat capacity of the rotor 1 which
are obtained in advance. The rotation of the rotor 1 can be
controlled with elaboration by the rotation control unit 26 on the
basis of those calculated temperatures so that the rotor
temperature and the magnet temperature do not exceed the limit
temperature. As a result, the higher efficiency and the higher
torque of the motor 100 can be realized.
Second Embodiment
[0102] Subsequently, a description will be given in detail of a
motor according to a second embodiment of the present invention
with reference to FIG. 3. In the figure, the same configurations as
those in the first embodiment are denoted by identical symbols, and
their detailed description will be omitted.
[0103] A motor 200 according to the second embodiment is different
from that of the first embodiment in that the rotor 1 provides an
oil supply path 8 extending from a bottom of the oil reservoir unit
4 to the end of the rotor 1 at the reducer 40 side along the
rotating shaft line L. Also, the housing 41 forms an oil supply
path 48, and the oil supply path 48 communicates between an oil
pool 47 demarcated by the end of the rotor 1 and the housing 41,
and the oil storage chamber 42 so that the oil within the oil
storage chamber 42 can flow into the oil supply path 8 through the
oil pool 47. An oil seal 46 is provided between the rotor 1 and the
housing 41 so that the oil in the oil pool 47 is not leaked into
the oil storage chamber 42.
[0104] In the second embodiment, unlike the first embodiment, when
the motor cover 20 is fitted to the motor case 51, there is no need
to pour the oil P into the oil reservoir unit 4 in advance. That
is, when the motor cover 20 is fitted to the motor case 51, a part
of the temperature sensor 30 is inserted into the oil reservoir
unit 4 in a state where the oil P is not reserved in the oil
reservoir unit 4. Then, after the motor cover 20 and the reducer 40
are fitted to the motor case 20, the coil 3 of the motor 200 is
energized to rotate the rotor 1 at a desired rotating speed, and
rotate the shaft 44 of the reducer 40. As a result, the oil P
reserved in the oil storage chamber 42 of the housing 41 is
diffused to and flows into the oil supply path 48. The oil P that
has flowed into the oil supply path 48 is supplied to the oil
supply path 8 of the rotor 1 through the oil pool 47. Further, the
oil P is supplied to the oil reservoir unit 4 that fluidically
communicates with the oil supply path 8. For example, an on-off
valve (not shown) is provided in the oil supply path 48, and after
the oil P of a desired amount is reserved in the oil reservoir unit
4, the on-off valve may be closed to stop the supply of the oil.
Also, a height of a top of the oil supply path 48 formed in the
housing 41 in the vertical direction is set to be relatively higher
than a height of the oil reservoir unit 4 in the vertical
direction, thereby being capable of surely supplying the oil P, to
the oil reservoir unit 4 of the rotor 1. Also, in the second
embodiment, even if the oil P in the oil reservoir unit 4 is leaked
from the oil seal 6, the oil reservoir unit 4 is replenished with
the oil P through the oil supply path 8 so that the oil P of a
desired amount can be reserved in the oil reservoir unit 4. When
the oil P of a given amount or more is reserved in the oil
reservoir unit 4, an oil pressure in the oil supply path 8 is
adjusted so that the oil P can be discharged from the oil reservoir
unit 4 to the oil supply path 8.
Third Embodiment
[0105] Subsequently, a description will be given in detail of a
motor according to a third embodiment of the present invention with
reference to FIG. 4. In the figure, the same configurations as
those in the first and second embodiments are denoted by identical
symbols, and their detailed description will be omitted.
[0106] A motor 300 according to the third embodiment is different
from the motor 200 of the second embodiment in that the oil supply
path 8 includes an oil inflow path 11 and an oil outflow path 13,
and also different from the motor 100 of the first embodiment in
that there is provided an oil circulation path 18 mainly including
the oil inflow path 11 and the oil outflow path 13 in the interior
of the rotor 1, and the oil storage chamber 42 and the oil supply
path 48 within the housing 41. The oil P high in thermal
conductivity reserved in the oil storage chamber 42 is circulated
in the interior of the oil circulation path 18 so that the heat
radiation from the rotor 1 can be sucked to cool the rotor 1. As
the lengths of the oil reservoir unit 4 and the temperature sensor
30 in the direction of the rotating shaft line L are longer, the
temperature of the rotor 1 can be detected with higher precision.
In the motor 300 according to the third embodiment, in order to
ensure the oil circulation path 18, the lengths of the oil
reservoir unit 4 and the temperature sensor 30 in the direction of
the rotating shaft line L are relatively short as compared with
those in the first and second embodiments.
[0107] The above oil circulation path 18 will be described in
detail. First, when the coil 3 of the motor 300 is energized to
rotate the rotor 1 and the shaft 44, the oil reserved within the
oil storage chamber 42 is diffused to and flows in the oil supply
path 48. Thereafter, the oil passes through the oil pool 47, and
flows into the oil inflow path 11 through an inflow port 12 formed
in the end of the rotor 1. The oil within the oil inflow path 11
mainly flows in the direction of the rotating shaft line L of the
rotor 1, passes through a coupling path 15 in the radial direction
which is provided in the vicinity of the opposite end of the oil
inflow path 11, and flows outside of the oil inflow path 11 in the
radial direction. The oil outflow path 13 fluidically communicated
with the coupling path 15 is disposed outside of the oil inflow
path 11 in the radial direction. The oil that has flowed into the
coupling path 15 flows in the interior of the oil outflow path 13
in the rotating shaft line L direction (direction opposite to the
inflow direction) of the rotor 1. Then, the oil is discharged into
the oil storage chamber 42 through an outflow port 14 formed in the
end of the oil outflow path 13. The oil circulation path 18 of the
oil P for rotor cooling is thus formed. The oil circulation path 18
absorbs the heat of the rotor 1 while the oil P is passing through
the oil inflow path 11, the oil outflow path 13, and the coupling
path 15, and the heat radiated from the rotor 1 is radiated to the
external of the motor 300. As illustrated in the figure, since the
oil outflow path 13 is disposed outside of the oil inflow path 11
in the radial direction, the heat radiated from the rotor 1 is
mainly absorbed by the oil within the oil outflow path 13, and the
oil can be rapidly discharged to the outside of the rotor 1. As a
result, the rotor 1 can be efficiently cooled.
[0108] The oil inflow path 11 and the oil outflow path 13 in the
oil circulation path 18 is isolated from the oil reservoir unit 4
by a partition 17. However, a continuous hole 16 is pierced
substantially in the center (on the rotating shaft line L of the
rotor 1) of the partition 17, and the oil inflow path 11 and the
oil reservoir unit 4 fluidically communicate with each other
through the continuous hole 16. With the provision of the
continuous hole 16, a part of the oil P flowing in the oil inflow
path 11 can be supplied to the oil reservoir unit 4 through the
continuous hole 16, and the oil P in the oil reservoir unit 4 can
be discharged to the oil inflow path 11 through the continuous hole
16.
[0109] Since a part of the oil P flowing in the oil circulation
path 18 is thus supplied to the oil reservoir unit 4 through the
continuous hole 16, there is no need to pour the oil P into the oil
reservoir unit 4 in advance in the third embodiment, as in the
second embodiment. That is, in an initial stage where the oil P is
circuited in the oil circulation path 18, the coil 3 of the motor
300 is energized to rotate the rotor 1 at a desired rotating speed
so that the oil P in the oil storage chamber 42 can be supplied to
the oil reservoir unit 4. In order to efficiently supply the oil P
to the oil reservoir unit 4, a spiral groove (not shown) may be
formed in a part of the oil inflow path 11 or the inner peripheral
surface of the continuous hole 16 in advance, and the oil P may be
guided to the oil reservoir unit 4. Also, an on-off valve (not
shown) may be provided in the oil outflow path 13 or the coupling
path 15, and the on-off valve may be closed to close the oil
outflow path 13 or the coupling path 15 until the oil P of a
desired amount is reserved in the oil reservoir unit 4, and
thereafter the on-off valve may be opened to circulate the oil P in
the oil circulation path 18. Also, in the third embodiment, as in
the second embodiment, even if the oil P in the oil reservoir unit
4 is leaked from the oil seal 6, the oil reservoir unit 4 can be
replenished with a part of the oil that circulates in the oil
circulation path 18 through the continuous hole 16. As a result,
the oil P of a desired amount can be reserved in the oil reservoir
unit 4.
[0110] FIG. 5 illustrates a relationship between the oil P poured
into the oil reservoir unit 4 and the temperature sensor 30
according to the third embodiment. FIG. 5(a) illustrates the motor
stop state, and FIG. 5(b) illustrates the motor drive state.
[0111] As illustrated in FIG. 5(a), when the motor 300 is arranged
in the vehicle so that the rotating shaft line L of the rotor 1
becomes horizontal, in the stop state of the motor 300, the oil P
pools in the lower side of the oil reservoir unit 4. In the third
embodiment, with the provision of the continuous hole 16, if the
oil P is supplied to the oil reservoir unit 4 by an amount larger
than a given amount, and reserved at a position higher than a
height of the continuous hole 16, unnecessary oil P which is
reserved at the position higher than the continuous hole 16 can be
discharged to the oil inflow path 11 through the continuous hole
16. Thus, in the third embodiment, a height of the oil P reserved
in the oil reservoir unit 4 can be limited to be lower than that of
the continuous hole 16 to optimize the amount of oil P in the oil
reservoir unit 4. In order to reserve the oil P of the amount as
large as possible within the oil reservoir unit 4, and transmit the
heat between the rotor 1 and the temperature sensor 30 through the
oil P, for example, at the time of driving the motor 300, it is
preferable to decrease an inner diameter A of the continuous hole
16 as much as possible. The pressure of the oil flowing in the oil
inflow path 11 is adjusted so that the oil P in the oil reservoir
unit 4 can be reserved up to a position higher than that of
continuous hole 16.
[0112] As in the third embodiment, when the continuous hole 16 is
formed between the oil reservoir unit 4 and the oil inflow path 11,
if the motor 300 is arranged in the vehicle so that the rotating
shaft line L becomes vertical, that is, the motor cover 20 is
disposed at the vertically upper portion, there is a possibility
that the oil P reserved on the end (vertically lower portion) of
the oil reservoir unit 4 opposite to the motor cover 20 side is
discharged to the oil inflow path 11 through the continuous hole
16. For that reason, in the third embodiment, it is preferable that
the motor 300 is arranged in the vehicle so that the rotating shaft
line L of the rotor 1 becomes horizontal. If the motor 300 is
arranged so that the rotating shaft line L of the rotor 1 becomes
vertical, the oil pressure in the oil inflow path 11 is adjusted,
for example, a one-way valve may be provided in the continuous hole
16 so as to suppress the discharge of the oil P to the oil inflow
path 11.
[0113] As illustrated in FIG. 5(b), when the motor 300 is driven,
the oil P in the oil reservoir unit 4 is thrust outside of the oil
reservoir unit 4 in the radial direction by its centrifugal force,
and a layer of the oil P is formed on the inner peripheral surface
of the oil reservoir unit 4. Even in this state, in order to detect
the temperature of the rotor 1 by the temperature sensor 30 with
high precision, as in the first embodiment, there is a need to
reserve the oil P in the oil reservoir unit 4 by the amount of
.pi.(D.sup.2-d.sup.2)L1/4 or more.
[0114] Thus, in the third embodiment, a part of the oil P that
circulates for cooling the rotor 1 is reserved in the oil reservoir
unit 4, and the temperature of the rotor 1 can be detected through
the reserved oil P. As a result, the influence attributable to the
circulation state such as the inflow temperature, the flow rate, or
the flow velocity of the circulating oil P can be suppressed to
detect the temperature of the rotor 1 with high precision. Also,
because the oil P can be reserved in the oil reservoir unit 4 with
the use of the circulating oil P, a process of pouring the oil P
into the oil reservoir unit 4 from the external in advance becomes
unnecessary, and the manufacturing process of the motor can be
simplified.
Fourth Embodiment
[0115] Subsequently, a description will be given in detail of a
motor according to a fourth embodiment of the present invention
with reference to FIG. 4. In the figure, the same configurations as
those in the first to third embodiments are denoted by identical
symbols, and their detailed description will be omitted.
[0116] FIG. 6 illustrates an embodiment when a lubricating oil high
in the thermal conductivity for cooling the bearing is used as the
oil P which is reserved in the oil reservoir unit 4.
[0117] The above lubricating oil P flows in an oil supply path 19
provided along the rotating shaft line L of the rotor 1 from one
end of the rotor 1, passes through an oil discharge path 19A
disposed in the vicinity of the end of the oil reservoir unit 4
side and extending in the radial direction, and is transmitted to
an oil storage unit 64 demarcated by an inner surface 60A of a
motor cover 60, the rotor 1, and oil seals 61, 62. A bearing 63
fitted to the inner surface 60A of the motor cover 60 is
accommodated in the oil storage unit 64, and the bearing 63 is
cooled by an oil PA within the oil storage unit 64. Also, the oil
PA that absorbs the heat of the bearing 63 and reaches a high
temperature passes through an oil discharge path 69 formed in the
interior of the motor cover 60, and is discharged to the external
of a motor 400. The lubricating oil is supplied from an oil storage
chamber for the lubricating oil not shown to the oil supply path
19.
[0118] As in the first embodiment, a rotating angle sensor 65 is
fitted to the inner surface 60A of the motor cover 60, and
connected to rotation control means not shown so as to control the
rotating speed of the rotor 1. Also, an opening portion 68 is
formed substantially in the center (on the rotating shaft line L of
the rotor 1) of the motor cover 60, and the temperature sensor 30
is attached to pass through the opening portion 68.
[0119] In this example, the partition 17 is disposed between the
oil supply path 19 and the oil reservoir unit 4 as in the third
embodiment, and the continuous hole 16 is formed substantially in
the center of the partition 17 so that a part of the oil P flowing
in the oil supply path 19 is supplied to the oil reservoir unit
4.
[0120] In the fourth embodiment, as in the third embodiment, when
the motor cover 60 is fitted to the motor case 51, there is no need
to pour the oil P into the oil reservoir unit 4 in advance. That
is, after the motor cover 60 is fitted to the motor case 51, the
rotor 1 is rotated at a desired rotating speed so that a part of
the oil P flowing in the oil supply path 19 can be supplied to the
oil reservoir unit 4 through the continuous hole 16.
[0121] The four embodiments of the present invention have been
described above. However, the present invention is not limited to
the above embodiments, but can be variously modified in design
without departing from the spirit of the invention disclosed in the
claims.
[0122] As understandable from the above description, according to
the first to fourth embodiments, the rotor temperature can be
detected through the oil which is reserved in the oil reservoir
unit. That is, because there is no need to consider the influence
of the inflow temperature, the flow rate, and the flow velocity of
the oil in measuring the oil temperature reserved in the oil
reservoir unit, the rotor temperature can be detected with easy and
high precision on the basis of the above measurement result.
Further, when the magnet is embedded within the rotor, because the
magnet temperature can be calculated with high precision on the
basis of the detected rotor temperature, the rotating speed of the
rotor can be controlled to suppress the demagnetization of the
magnet. As a result, the motor can be driven with a high torque and
a high efficiency for a long duration.
[0123] The present invention is not limited to the above first to
fourth embodiments, but includes a variety of modified examples.
For example, the above first to fourth embodiments are described in
detail for facilitation to understand the present invention, and
the present invention does not always provide all of the
configurations described above. Also, a part of one configuration
example can be replaced with another configuration example, and the
configuration of one embodiment can be added with the configuration
of another embodiment. Also, in a part of the respective first to
fourth embodiments, another configuration can be added, deleted, or
replaced.
[0124] Also, control lines and information lines necessary for
description are illustrated, and all of the control lines and the
information lines necessary for products are not illustrated. In
fact, it may be conceivable that most of the configurations are
connected to each other.
* * * * *