Title: Electric compressor
Abstract: In an electric compressor, in which an electric motor and a compressor driven thereby are integrated, in order to prevent a reduction in the durability of the electric motor and the like due to heat conducted from heat radiating bodies such as drive circuits, a fluid, prior to being taken into the compressor portion, is circulated through the electric motor portion as a medium for cooling. In this case, a plurality of cooling medium passages for example are provided parallel to the axis of rotation, and the endothermic capacity of passages formed in the vicinity of heat radiating bodies is made greater than the endothermic capacity of passages formed in other portions.
Patent Number: 6,997,687 Issued on 02/14/2006 to Iritani
| Inventors:
|
Iritani; Kunio (Anjo, JP)
|
| Assignee:
|
Denso Corporation (Kariya, JP)
|
| Appl. No.:
|
423930 |
| Filed:
|
April 28, 2003 |
Foreign Application Priority Data
| May 01, 2002[JP] | 2002-129960 |
| Current U.S. Class: |
417/371; 310/62 |
| Current Intern'l Class: |
F04B 35/04 (20060101); H02K 9/16 (20060101) |
| Field of Search: |
310/52,54,62
417/366,371
|
References Cited [Referenced By]
U.S. Patent Documents
| 5908286 | Jun., 1999 | Clemmons.
| |
| 6198183 | Mar., 2001 | Baeumel et al.
| |
| 6419460 | Jul., 2002 | Dantlgraber.
| |
| 6524082 | Feb., 2003 | Morita et al.
| |
| Foreign Patent Documents |
| A-7-288949 | Oct., 1995 | JP.
| |
| A-2002/-5024 | Jan., 2002 | JP.
| |
Primary Examiner: Koczo, Jr.; Michael
Attorney, Agent or Firm: Posz Law Group, PLC
Claims
What is claimed is:
1. An electric compressor comprising:
a housing;
an electric motor portion, wherein the electric motor portion is housed in the
housing and includes a stator portion and a rotor portion;
a drive circuit portion for operating the electric motor portion, wherein the
drive circuit portion is integrated with part of the periphery of the housing;
a compressor portion driven by the electric motor portion for compressing a fluid,
wherein the compressor portion is housed in the housing; and
a plurality of cooling medium passages provided between the inner surface of
the housing and the outer surface of the stator portion to circulate fluid taken
in by the compressor portion prior to compression as a cooling medium through the
electric motor portion and, among the cooling medium passages, cooling medium passages
that are located in proximity to the drive circuit portion have a greater endothermic
capacity than others of the cooling medium passages that are not located in proximity
to the drive circuit portion.
2. The electric compressor of claim 1, wherein a cross sectional area of the
cooling medium passages that are located in proximity to the drive circuit portion
is greater than a cross sectional area of the other cooling medium passages.
3. The electric compressor of claim 1, wherein a surface area of the cooling
medium passages that are located in proximity to the drive circuit portion is greater
than a surface area of the other cooling medium passages.
4. The electric compressor of claim 3, wherein, in order to increase the surface
area of the cooling medium passages, the cooling medium passages include an uneven surface.
5. The electric compressor of claim 4, wherein the uneven surface is formed on
only one surface of the cooling medium passages.
6. The electric compressor of claim 1, wherein the electric compressor is located
in proximity to a relatively hot body other than the drive circuit portion, and
cooling medium passages that are located in proximity to the drive circuit portion
are first passages, and the other cooling medium passages, which are not located
in Proximity to the drive circuit portion are second passages, and the electric
compressor includes additional cooling medium passages, which are third passages,
and the third passages are located in proximity to the relatively hot body, and
the endothermic capacity of the third passages, is greater than the endothermic
capacity of the second passages.
7. The electric compressor of claim 6, wherein the cross sectional area of the
first passages is greater than the cross sectional area of the second passages,
and the cross sectional area of the third passages is greater than the cross sectional
area of the second passages.
8. The electric compressor of claim 6, wherein the surface area of the first
passages is greater than the surface area of the second passages, and the surface
area of the third passages is greater than the surface area of the second passages.
9. The electric compressor of claim 6, wherein, in order to increase the surface
area of the cooling medium passages, the cooling medium passages include an uneven surface.
10. The electric compressor of claim 1, wherein the cooling medium passages are
disposed parallel to a rotating shaft of the electric motor portion.
11. The electric compressor of claim 1, wherein the electric compressor is used
as a refrigerant compressor for an automotive air-conditioning system, and the
cooling medium is refrigerant returning from an evaporator.
12. The electric compressor of claim 6, wherein the relatively hot body other
than the drive circuit portion is an internal combustion engine.
13. An electric compressor comprising:
a housing;
an electric motor, wherein the electric motor is housed in the housing and includes
a stator and a rotor;
a drive circuit for operating the electric motor, wherein the drive circuit is
integrated with an outer surface of the housing and produces heat;
a compressor driven by the electric motor for compressing a fluid, wherein the
compressor is housed in the housing;
a plurality of cooling passages provided between the inner surface of the housing
and the outer surface of the stator to conduct a coolant fluid, which is to enter
the compressor and be compressed, through the electric motor to cool the motor,
and wherein the plurality of cooling passages include first cooling passages, which
are located generally between the drive circuit and the stator in a relatively
more heated portion of the housing, and second passages, which are not located
in proximity to the drive circuit and are located in a relatively less heated portion
of the housing, and wherein the first cooling passages have a greater endothermic
capacity than the second cooling passages.
Description
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an electric compressor in which an electric
motor portion and a compressor portion are integrated and, in particular, to an
electric compressor in which a drive circuit portion for supplying electric power
to the electric motor portion is integrated with the compressor portion.
2. Description of the Related Art
Attempts have been made to integrate a refrigerant compressor, for an air-conditioning
system mounted in an automobiles, with an electric motor for rotatably driving
the refrigerant compressor via a common rotating shaft, and to integrate a drive
circuit portion, such as an inverter for supplying power to the electric motor,
with the electric motor, in order to reduce the amount of wasted space and the
size and weight of the overall structure, by using, in conjunction, as many components
as possible, to facilitate installation of the compressor in a vehicle where there
is not enough space, to simplify the arrangement of the transmission shaft, wiring,
piping and the like linking the various components, and to reduce the cost.
When integrating a refrigerant compressor and electric motor in this way, as
a means for cooling the electric motor, in which overheating is a problem due to
the density of installation, a method of guiding a low temperature intake refrigerant,
consisting mainly of gas returning to the refrigerant compressor from the evaporator
during the refrigeration cycle, and cooling the inside of the electric motor by
circulating this gas through the electric motor, can be performed. For this purpose,
in the prior art, a passage for circulating the intake refrigerant, formed between
the stator of the electric motor and the housing enclosing this, is normally provided
uniformly surrounding the rotating shaft of the electric motor.
Consequently, where a heat radiating body such as a drive circuit portion
including an inverter is integrated with part of the periphery of the housing of
the electric motor and with other heat radiating bodies disposed in proximity thereto,
due to heat emitted from the heat radiating bodies of the drive circuit portion
and the like, part of the electric motor attached or in proximity thereto suffers
from a localized rise in temperature because it cannot be sufficiently cooled,
the temperature around the rotating shaft of the electric motor becomes non-uniform,
and oscillation problems or the like occur due to differences in the minute space
between the stator and armature as a result of localized heat expansion differences,
resulting in a non-uniform magnetic field being generated by the stator and rotational
imbalance, thus reducing efficiency. Also, because the drive circuit components
such as the inverter and the like are not sufficiently cooled by indirect cooling
alone from the inside of the electric motor by means of intake refrigerants returning
to the compressor, there is a problem of a reduction in the durability of the drive
circuit components.
SUMMARY OF THE INVENTION
The present invention, in light of the above problems of the prior art, has as
its object, in the case of integrating an electric motor, a compressor driven thereby,
and a drive circuit portion for supplying power to the electric motor, to guide
a fluid that is introduced into the compressor to the electric motor, to uniformly
cool the electric motor by circulating it therethrough, and to sufficiently cool
the electric motor drive circuit portion integrally attached to a portion of the
housing of the electric motor, thereby simultaneously solving the problems generated
by non-uniform and insufficient cooling.
In the electric compressor of the present invention, in which an electric motor
portion, a drive circuit portion including an inverter for operating the electric
motor portion, and a compressor portion driven by the electric motor portion for
compressing a fluid are integrated, in order to circulate the fluid taken in by
the compressor portion prior to compression, as a cooling medium through the electric
motor portion, a plurality of cooling medium passages are provided in the electric
motor portion, among which those cooling medium passages provided in the vicinity
of the drive circuit portion can have a greater endothermic capacity than that
of the cooling medium passages provided in other portions. The drive circuit portion
mentioned here includes a portion that is installed directly on to the electric
motor housing, i.e. at least the electric motor housing side portion of the casing
of the drive circuit portion is integrated with the electric motor housing.
In order to increase endothermic capacity, such methods as increasing the cross
sectional area of the cooling medium passages or increasing the surface area of
the cooling medium passages can be used. Other methods for increasing the endothermic
capacity of the cooling medium passages include imparting different flow rates
between the plurality of the cooling medium passages and imparting different temperatures
to the circulating cooling medium; when imparting a difference in temperature,
a method of the circulating a cooling medium, whose temperature has been increased
by being circulated through the cooling medium passages in those portions where
the endothermic capacity increases, through the cooling medium passages in those
portions where the endothermic capacity is not required to be increased can, for
example, be used.
In either case, as heat radiating bodies that increase the endothermic capacity
of the cooling medium passages and which correspond to those portions of the cooling
medium passages whose cross sectional area or surface area is to be increased,
not only is there the drive circuit portion, but also heat radiating bodies such
as an internal combustion engine mounted in the vehicle, for example.
In this way, the endothermic capacity of portions of the cooling medium passages
corresponding to heat radiating bodies such as the drive circuit portion of the
electric motor portion and the internal combustion engine disposed in proximity
thereto can be increased, thereby avoiding the problem of a localized temperature
rise in part of the electric motor portion, non-uniform temperature states around
the rotating shaft of the electric motor portion, and partial heat expansion differences
that result in vibrations and the like due to differences in the minute spaces
between the stator and armature, as well as the problem of an irregular magnetic
field generated by the stator resulting in rotational imbalance and a reduction
in efficiency. Also, a reduction in the durability of the drive circuit portion
itself due to insufficient cooling can be prevented.
A specific method for increasing the surface area of the cooling medium passages
is to make a surface of the cooling medium passages an uneven surface. This uneven
surface may be formed only on one surface of the cooling medium passages. The cooling
medium passages may be disposed parallel to the rotating shaft of the electric
motor portion, or may be imparted differences in endothermic capacity by disposing
part of the plurality of cooling medium passages in a non-linear winding pattern.
When the electric compressor of the present invention is used as a refrigerant
compressor for an automotive air-conditioning system, a refrigerant taken into
the refrigerant compressor and returning from the evaporator during the refrigeration
cycle can be used as the cooling medium to be circulated through the cooling medium
passages. The effects of the present invention can thereby be maximized.
BRIEF DESCRIPTION OF THE DRAWINGS
FIG. 1 is a sectional view illustrating the concept of the overall structure
of the electric compressor common to all of the embodiments.
FIG. 2 is a block diagram of a refrigeration cycle illustrating a case where
the electric compressor of the present invention is used.
FIG. 3 is a cross sectional side view showing a first embodiment of the main
portions of the electric compressor.
FIG. 4 is a cross sectional side view showing a second embodiment.
FIG. 5 is a cross sectional side view showing a third embodiment.
FIG. 6 is a cross sectional side view showing a fourth embodiment.
FIG. 7 is a cross sectional side view showing a fifth embodiment.
FIG. 8 is a cross sectional side view showing a sixth embodiment.
FIG. 9 is a cross sectional side view showing a seventh embodiment.
FIG. 10 is a cross sectional side view showing an eighth embodiment.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
By reference to the attached drawings, the preferred embodiments of the present
invention will be explained in detail. FIG. 1 illustrates the overall structure
of the electric compressor common to eight specific embodiments of the present
invention, relating to the main components of the electric compressor, shown in
FIGS. 3 to 10, and FIG. 2 shows, in abbreviated form, the structure of a refrigeration
cycle common to all of the embodiments, in a case where the electric compressor
of the embodiments of the present invention is used as a refrigerant compressor
in a refrigeration cycle of an air-conditioning system mounted in a vehicle such
as an automobile.
In FIG. 1, the electric compressor
1 of the embodiments, for example,
an
air-conditioning system mounted in a vehicle, comprises a compressor portion
2
comprising a compressor such as a scroll type compressor or swash plate type compressor
used as a refrigerant compressor, an electric motor portion
3, integrated
with the compressor portion
2 on the axis of a common rotating shaft not
shown in the drawing, for rotatably driving the compressor portion
2, and
a drive circuit portion
5 integrally attached to part of the peripheral
surface of the housing
4 of the electric motor portion
3 and containing
an inverter or the like for supplying power to the electric motor portion
3.
However, the present invention is not characterized by the specific structures
of the compressor portion
2 and the drive circuit portion
5, nor
by the form, structure and the like of the electric motor portion
3 itself,
therefore most of the internal structures thereof have been omitted in the attached drawings.
In order to cool the electric motor portion
3 from the inside, an intake
port
6 for receiving fluid (in this case a vaporized refrigerant) to be
compressed in the compressor portion
2 is provided at the end portion of
the electric motor portion
3 opposite the compressor portion
2. Meanwhile,
an exhaust port
7 for discharging the fluid to be compressed in the compressor
portion
2 is provided in part of the compressor portion
2 itself.
Consequently, the refrigerant (intake refrigerant) to be compressed in the compressor
portion
2 enters through the intake port
6 and flows into the housing
4 of the electric motor portion
3 in the direction of the arrow,
is compressed in the compressor portion
2 after cooling the interior of
the electric motor portion
3, and is discharged as a compressed refrigerant
(discharge refrigerant) through the exhaust port
7 to the exterior of the
electric compressor
1. The housing
4 of the electric motor portion
3, the casing
8 enclosing the drive circuit portion
5 for
maintaining a waterproof quality, and the like, are produced from an aluminum alloy
having suitable thermal conductivity.
In the case of the refrigeration cycle of the air-conditioning system shown in
FIG. 2, although the electric compressor
1 is disposed in the vicinity of
the engine
9 (internal combustion engine) to drive the vehicle, it is not
directly driven by the crank shaft of the engine
9, but is driven by power
supplied to the drive circuit portion
5 from a battery charged by a generator
(not shown in the drawing) attached to the engine
9. The refrigerant compressed
in the compressor portion
2 of the electric compressor
1 is discharged
from the exhaust port
7 and flows into a condenser
10, which is a
first heat exchanger, and radiates the heat produced during compression to the
external atmosphere to liquefy the refrigerant. The liquid refrigerant is decompressed
while passing through a throttle
11 such as an expansion valve, and flows
in a gas/liquid mixture state into an evaporator
12, which is a second heat
exchanger, to cool the air inside the vehicle when it is vaporized.
Stated briefly, the structural features of the electric compressor of the
present invention can be said to reside in the form or structure, in cross section,
of the electric motor portion
3 shown along the line A—A in FIG. 1.
That is, the cross section A—A is the relevant part of the present invention,
the form or structure thereof varying as explained below to distinguish the eight
embodiments shown in FIGS. 3 to 10. Consequently, the structures of the embodiments
are all the same except for these variations.
A first embodiment relating to the relevant part (cross section A—A) of
the
electric compressor of the present invention is shown in FIG. 3. Although this
is a structure common to all of the embodiments, the electric motor portion
3
has a mainly ring-shaped stator portion
13 fixedly supported by a cylindrical
surface formed inside the housing
4 of the electric motor portion
3,
and a mainly cylindrical rotor portion
15 rotatably supported by a central
rotating shaft
14 so that there is a slight gap between it and the inner
peripheral surfaces of the stator portion
13, which has a comb-like shape.
The rotating shaft
14 connects to a drive shaft, not shown in the drawing,
of the compressor portion
2 on the same axis. Coils
16 are wound
into slots (grooves) on the inner periphery of the stator portion
13. These
coils
16 produce a rotating magnetic field moving in a predetermined direction
on the fixed stator portion
13, by a three-phase alternating current (for
example) supplied from the inverter housed in the drive circuit portion
5,
and rotate the rotor portion
15 together with the magnetic field. The rotational
speed of the rotating magnetic field can be freely controlled by changing the frequency
of the three-phase alternating current applied to the coils
16 from the inverter.
As the electric motor portion
3 radiates heat from the coils
16
and the core that is the stator portion
13 and from the rotor portion
15,
it is necessary to cool these parts to eliminate this heat. Therefore, a plurality
of refrigerant passages are formed in groove shapes in the axial direction of the
rotating shaft
14 around the peripheral surface of the stator portion
13,
these refrigerant passages connecting at one end to the intake port
6 described
above, and connecting at the other end to an inlet of the compressor portion
2,
not shown in the drawing.
However, in the electric compressor
1 of the embodiment shown in
the drawing, the drive circuit portion
5 including an inverter is attached
to a portion
4a of the housing
4 of the electric motor portion
3, and because the inverter and the like also radiate heat, the temperature
of the electric motor housing
4 in the vicinity of the portion
4a
attached to the drive circuit portion
5 increases in comparison to a
portion
4b in the electric motor housing
4 located opposite
the portion
4a attached to the drive circuit portion
5. Consequently,
unless the portion
4a attached to the drive circuit portion
5
is cooled more strongly than the opposite portion
4b, the overall
temperature of the electric motor housing
4 cannot be equalized.
Thus, in the first embodiment of the present invention shown in FIG. 3, as
well as increasing the cross sectional area of a plurality of first refrigerant
passages
17 formed in the stator portion
13 in the vicinity of the
portion
4a connected to the drive circuit portion
5 to increase
the heat transfer surface area thereof, thus increasing the endothermic capacity
and amount of refrigerant circulating through these portions, the cross sectional
area and heat transfer surface area of a plurality of second refrigerant passages
18 formed in the stator portion
13 toward the portion
4b
opposite the portion
4a are made relatively small, consequently
decreasing the endothermic capacity thereof. Thus, among the low temperature refrigerant
(mainly gas) returning to the compressor portion
2 of the electric compressor
1 from the evaporator
12, the amount circulating in the first refrigerant
passages
17 is more than the amount circulating in the second refrigerant
passages
18, therefore the amount of heat absorbed by the refrigerant circulating
in the first refrigerant passages
17 is greater than the amount of heat
absorbed by the refrigerant circulating in the second refrigerant passages
18,
as a result of which the temperature of the stator portion
13 is substantially
uniform across its entire periphery and is cooled to a balanced state. Not only
can the previously described problems resulting from irregular cooling thereby
be avoided, but the inverter of the drive circuit portion
5 can also be
sufficiently cooled and operated without the possibility of deterioration.
FIG. 4 shows a second embodiment of the present invention. The second embodiment
is a further development of the first embodiment, and is characterized in that,
as the first refrigerant passages
17 in the vicinity of the portion
4a
attached to the heat radiating drive circuit portion
5 are formed from
grooves on the cylindrical inner wall of the electric motor housing
4 and
the cylindrical outer peripheral surface of the stator portion
13, by forming
a plurality of protrusions (folds) on both surfaces of the first refrigerant passages
17 along the axial direction of the rotating shaft
14, or an uneven
surface
19 comprising a plurality of protrusions or the like formed on both
surfaces, the surface area of the portion
4a of the electric motor
housing
4 close to the drive circuit portion
5 and portions where
the stator portion
13 comes into contact with the refrigerant, i.e. the
heat transfer surface area, is increased and the endothermic capacity of the first
refrigerant passages
17 can be made higher than that of the second refrigerant
passages
18. It is thereby possible to further increase the effects of the
first embodiment.
When it is not necessary to increase the endothermic capacity of the first refrigerant
passages
17 to the extent of the second embodiment, an uneven surface
19
comprising protrusions or the like in portions corresponding to the first refrigerant
passages
17 can be formed in the inner wall of the electric motor housing
4 as in the third embodiment shown in FIG. 5, or an uneven surface
19
can be formed in the bottom surface of the grooves forming the first refrigerant
passages
17 on the stator portion
13 side as in the fourth embodiment
shown in FIG. 6.
Also, when the electric compressor
1 is directly connected to a heat
radiating body having a large shape and thermal capacity such as the engine
9,
as in the refrigeration cycle example shown in FIG. 2, the electric compressor
1 receives not only heat radiated from the drive circuit portion
5
including the inverter, but it also receives heat conducted directly from the engine
9. Even if the electric compressor
1 is not directly connected to
the engine
9 but is rather disposed in the vicinity of the engine
9,
it still absorbs radiant heat emitted from the engine
9, resulting in non-uniform
temperature distribution due to localized temperature increases in the electric
compressor
1, and not only do the same problems as in the cases described
above occur, but due to an overall temperature rise in the electric compressor
1 there is a possibility of heat damage occurring.
When there are these kinds of concerns, by increasing the cross sectional area
and heat transferring area of not only the first refrigerant passages
17
which receive heat from the drive circuit portion
5, but also third refrigerant
passages
20 formed in a portion
4c which receives radiant
heat or heat conducted from the engine
9, and consequently increasing the
flow rate of refrigerants in these portions and the endothermic capacity attained
by this increase in flow rate over the amount in the second refrigerant passages
18, as in the fifth embodiment shown in FIG. 7, the endothermic capacity
of these portions is increased. Specifically,
21 is a mount for attaching
the electric compressor
1 to the engine
9 (the lower portion not
shown in FIG. 7) and supporting it, and comprises through holes
22 for integrating
the electric compressor
1 and for inserting bolts to attach the electric
compressor
1 to the engine
9. The lower surface of the mount
21
is a contact surface
21a (attachment surface) and contacts the engine
9. In this case
4b indicates a portion distanced from both
the previously described portions
4a and
4c in the
electric motor housing
4.
FIG. 8 is a sixth embodiment of the present invention. The sixth embodiment
is a further development of the fifth embodiment and is characterized by providing
uneven surfaces
19 on the cylindrical inner wall of the electric motor housing
4 and the bottom surfaces of the grooves of the cylindrical outer periphery
of the stator portion
13 forming the first refrigerant passages
17
in the vicinity of the portion
4a to which the casing
8 of
the drive circuit portion
5 that radiates heat is attached and the third
refrigerant passages
20 formed in the vicinity of the portion
4c
that receives heat from the engine
9. This increases the surface area
of the portions
4a and
4c of the electric motor housing
4 close to the drive circuit portion
5 and engine
9, and the
surface area of the stator portion
13 in contact with the refrigerant, i.e.
the heat transfer surface area, and increases the endothermic capacity of the first
refrigerant passages
17 and third refrigerant passages
20 over that
of the second refrigerant passages
18. The effects of the fifth embodiment
can thereby be increased even further.
When it is not necessary to increase the endothermic capacity of the first refrigerant
passages
17 and third refrigerant passages
20 to the extent of the
sixth embodiment, an uneven surface
19 can be formed in the bottom surface
of the grooves provided for forming the first refrigerant passages
17 and
third refrigerant passages
20 on the stator portion
13 side as in
the seventh embodiment shown in FIG. 9, or an uneven surface
19 can be formed
in portions corresponding to the first refrigerant passages
17 and third
refrigerant passages
20 in the inner wall of the electrical motor housing
4 as in the eighth embodiment shown in FIG. 10.
In the embodiments shown in the drawings, although the refrigerant passages
17,
18 and
20 are formed as grooves in the axial direction on the cylindrical
outer surface of the stator portion
13, these are no more than simple examples
and, where necessary, can be formed as narrow grooves in the axial direction in
the cylindrical inner surface of the electric motor housing
4, for example.
Needless to say, these refrigerant passages
17,
18 and
20
can also be formed in a shape other than a linear shape, for example as non-linear
winding-shaped grooves.
*
