Electric compressor

An electric compressor includes a housing, an electric motor, and an inverter. The housing includes a motor chamber. The electric motor includes a stator that includes a stator core, a plurality of first coils, a plurality of second coils, and a plurality of third coils. The first coils are connected in series, the second coils are connected in series, and the third coils are connected in series. One of the first coils that is located electrically closest to the first phase is referred to as a first specific coil, one of the second coils that is located electrically closest to the second phase is referred to as a second specific coil, and one of the third coils that is located electrically closest to the third phase is referred to as a third specific coil. The first to third specific coils are disposed above the shaft center of the drive shaft.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to Japanese Patent Application No. 2020-061979 filed on Mar. 31, 2020, the entire disclosure of which is incorporated herein by reference.

BACKGROUND ART

The present disclosure relates to an electric compressor.

Japanese Patent Application Publication No. 2001-280249 discloses a conventional electric compressor. The electric compressor includes a housing, a drive shaft, an electric motor, and a compression portion. The housing includes a bottom wall that extends in a radial direction of a shaft center of the drive shaft, and a peripheral wall that extends along the shaft center of the drive shaft. The bottom wall and the peripheral wall form a motor chamber in the housing. The housing further includes an inlet port. A pipe is connected to the inlet port through which refrigerant is drawn from an outside of the electric compressor into the housing.

The drive shaft is disposed in the housing including the motor chamber, and rotatable around the shaft center of the drive shaft. The electric motor is disposed in the motor chamber. The electric motor rotates the drive shaft around the shaft center of the drive shaft. Although not disclosed by the Publication No. 2001-280249, the electric motor is connected to an inverter disposed in the housing and hence driving of the electric motor is controlled. The compression portion is disposed in the housing. In the housing, the motor chamber and the inlet port are separated by the compression portion. The compression portion is driven by the drive shaft to compress the refrigerant.

Specifically, the inverter includes a first phase, a second phase, and a third phase through which the inverter is connected to the electric motor. The electric motor includes a stator and a rotor. The stator is fixed in the motor chamber. The drive shaft is fixed in the rotor. The rotor is disposed in the stator and rotatable with the drive shaft around the shaft center of the drive shaft.

The stator includes a stator core, a plurality of first coils, a plurality of second coils, and a plurality of third coils. The stator core is formed in a tubular shape extending along the shaft center of the drive shaft. The stator core includes a plurality of slots. The first through third coils are formed by winding conductor wires in the slots. Each first coil is electrically connected to the first phase. Each second coil is electrically connected to the second phase. Each third coil is electrically connected to the third phase. The first through third coils are connected to each other at the ends of the first through third coils opposite to the first through third phases.

In the electric compressor, each of the first to third coils is energized from the inverter to generate a magnetic field in each of the first to third coils in turn. This rotates the rotor with the drive shaft around the shaft center of the drive shaft in the stator. Thus, the compression portion compresses the refrigerant drawn from the inlet port.

Forming the first through third coils in the stator core includes performing a concentrated winding in which conductor wires are inserted into adjacent slots and performing a distributed winding in which conductor wires are inserted across a plurality of slots.

In recent years, electric compressors for coping with a high voltage of 600 volts or more are required. According to the inventors' verification, however, the first through third coils formed by the distributed winding are located close to each other, so that in a case where the high voltage described above is applied to the first through third coils, partial electric discharge tends to occur due to movement of electrons, which makes it easier for film of the conductor wires be damaged. Thus, reduction of durability of the stator and, eventually, reduction of durability of the electric compressor are concerned. As a measure against the problem, it is considered that the electric motor including the coils formed by the concentrated winding and series winding is provided in the electric compressor.

In some electric compressors, refrigerant caused to pass through the motor chamber to thereby cool the electric motor with the refrigerant. The refrigerant contains lubricant oil. Part of the refrigerant is liquefied in the motor chamber to form liquid refrigerant. Thus, the lubricant oil contained in the refrigerant may be accumulated in the motor chamber with the liquid refrigerant. Therefore, the stator disposed in the motor chamber may cause part of the first through third coils to be immersed in the lubricant oil and the liquid refrigerant.

When the lubricant oil and the refrigerant flows through the pipe, external moisture may pass through the pipe and be inevitably mixed with the lubricant oil and the refrigerant. Thus, the lubricant oil and the liquid refrigerant that are mixed with the moisture are reduced in volume resistivity. Therefore, such first through third coils that are immersed in the lubricant oil and the liquid refrigerant may easily cause electric leakage from the conductor wire to the housing. The reduction of durability of the electric compressor is concerned also in this respect.

The present disclosure is made in view of the above-described circumstances and directed to providing an electric compressor excellent in durability while coping with high voltage.

SUMMARY

In accordance with an aspect of the present disclosure, an electric compressor includes a housing, a drive shaft, an electric motor, a compression portion, and an inverter. The electric motor is configured to rotate the drive shaft. The compression portion is configured to be driven by the drive shaft to compress refrigerant. The inverter includes a first phase, a second phase, and a third phase that are electrically connected to the electric motor to form a three-phase alternating current. The inverter controls driving the electric motor. The housing includes a motor chamber that houses the electric motor and through which refrigerant passes. The electric motor includes a stator that is fixed to the housing and disposed in the motor chamber, and a rotor to which the drive shaft is fixed. The rotor is disposed in the stator and rotatable with the drive shaft. The stator includes: a stator core that has a tubular shape and extends in a direction of a shaft center of the drive shaft; a plurality of first coils formed by winding, to the stator core, a first conductor wire that is electrically connected to the first phase; a plurality of second coils formed by winding, to the stator core, a second conductor wire that is electrically connected to the second phase; and a plurality of third coils formed by winding, to the stator core, a third conductor wire that is electrically connected to the third phase. The first coils are connected to each other in series, the second coils are connected to each other in series, and the third coils are connected to each other in series. One of the first coils that is located electrically closest to the first phase is referred to as a first specific coil, one of the second coils that is located, electrically closest to the second phase is referred to as a second specific coil, and one of the third coils that is located electrically closest to the third phase is referred to as a third specific coil. The first specific coil, the second specific coil, and the third specific coil are disposed above the shaft center of the drive shaft.

Other aspects and advantages of the disclosure will become apparent from the following description, taken in conjunction with the accompanying drawings, illustrating by way of example the principles of the disclosure.

DETAILED DESCRIPTION OF THE EMBODIMENTS

The following will describe embodiments of the present disclosure with reference to the drawings Specifically, an electric compressor of one embodiment of the present disclosure is a scroll type electric compressor.

As illustrated inFIG.1, the electric compressor of the present embodiment includes a housing1, a drive shaft3, an electric motor5, a compression portion7, and an inverter9. The housing1includes a housing body11, a rear cover13, and an inverter cover15. The electric compressor is mounted in a vehicle (not illustrated) and forms a refrigerant circuit for the vehicle.

In the present embodiment, a back and forth direction, and an up and down direction of the electric compressor are defined by a solid left-right arrow and a solid up-down arrow illustrated inFIGS.1and2. The up and down direction of the electric compressor is defined by a solid up-down arrow illustrated inFIG.3as inFIG.1, and a right and left direction, or a width direction of the electric compressor is defined by a solid left-right arrow illustrated inFIG.3. The back and forth direction, the up and down direction, the right and left direction of the electric compressor correspond to a back and forth direction, an up and down direction, a right and left direction of the vehicle, respectively. That is, the electric compressor is mounted in the vehicle in a posture in which a front side of the electric compressor is a front side of the vehicle and a rear side of the electric compressor is a rear side of the vehicle. In addition, the electric compressor is mounted in the vehicle in a posture in which an upper side of a motor chamber111, which is described later, including an upper side of the electric compressor is an upper side of the vehicle and a lower side of the motor chamber111including a lower side of the electric compressor is a lower side of the vehicle. The electric compressor may be mounted in the vehicle in a posture in which the front side of the electric compressor is the rear side of the vehicle. Alternatively, the electric compressor may be mounted in the vehicle in a posture in which the front side of the electric compressor is a right side or a left side of the vehicle.

As illustrated inFIG.2, the housing body11includes a front wall11aand a peripheral wall11b. The front wall11ais located at the front end of the housing body11and extends in a radial direction of the housing body11. The peripheral wall11bis connected to the front wall11aand extends backward from the front wall11ain a direction of a shaft center O of the drive shaft3. The housing body11is formed in a bottomed cylindrical shape extending in the direction of the shaft center O by the front wall11aand the peripheral wall11b. The direction of the shaft center O is parallel to the back and forth direction of the electric compressor.

As illustrated inFIGS.2and3, the front wall11aand the peripheral wall11bform a motor chamber111inside the housing body11. The motor chamber111is separated from the outside of the housing body11and, eventually, the outside of the electric compressor by the front wall11aand the peripheral wall11b.

In the housing body11, an imaginary reference surface S is defined. As illustrated inFIG.3, the reference surface S includes the shaft center O and extends planarly in the motor chamber111. More specifically, the reference surface S extends horizontally in the motor chamber111to form a planar shape while overlapping with the shaft center O.

As illustrated inFIGS.1to3, the peripheral wall11bincludes an inlet port11c, a first mounting leg11d, a second mounting leg11e, and a plurality of bolt holes11f. The first mounting leg11dand the second mounting leg11eare examples of the mounting portion of the present disclosure. It is noted thatFIG.1illustrates one of the bolt holes11f.

The inlet port11cis disposed in the peripheral wall11bon the upper side of the motor chamber111and, eventually, on the upper side of the vehicle. More specifically, the inlet port11cis located in the peripheral wall11bon the upper side of the motor chamber111with respect to the reference surface S and the shaft center O. As illustrated inFIG.3, the inlet port11cextends on the left side of the electric compressor in the radial direction of the housing body11and provides communication between the outside of the housing body11and the motor chamber111. The inlet port11cis connected to an evaporator (not illustrated) through a pipe (not illustrated). Thus, the low-temperature and low-pressure refrigerant gas which has passed through the evaporator is drawn into the motor chamber111. That is, the motor chamber111serves also as a suction chamber. Since the inlet port11cis located in the peripheral wall11bon the upper side of the vehicle with respect to the reference surface S and the shaft center O, the refrigerant gas which has passed through the evaporator is drawn into the motor chamber111from the upper side of the vehicle with respect to the reference surface S and the shaft center O.

On the other hand, a storage area12is provided in the motor chamber111on the lower side of the vehicle with respect to the reference surface S. The storage area12is configured to store lubricant oil and liquid refrigerant. That is, the inlet port11cand the storage area12are separated from each other across the reference surface S in the up and down direction of the motor chamber111. Although a ratio of the storage area12to the motor chamber111varies depending on a storage amount of the lubricant oil and the liquid refrigerant, in the electric compressor, an amount of the lubricant oil, a size of the motor chamber111, and the like are designed so that the storage area12is not formed on the upper side of the vehicle with respect to the reference surface S or the inlet port11c, in other words, so that liquid level of the lubricant oil and the liquid refrigerant stored in the storage area12does not exceed the shaft center O and the inlet port11c.

The first mounting leg11dis disposed at a position of the peripheral wall11bthat is on the upper side of the vehicle with respect to the reference surface S and the shaft center O as in the case of the inlet port11c. That is, the inlet port11cis located in the peripheral wall11bcloser to the first mounting leg11dthan the reference surface S and the shaft center O. The first mounting leg11dis disposed at a position of the peripheral wall11bthat is on the upper side of the vehicle with respect to the inlet port11c. On the other hand, the second mounting leg11eis disposed at a position of the peripheral wall11bthat is on the lower side of the vehicle with respect to the reference surface S and the shaft center O. That is, the first mounting leg11dand the second mounting leg11eare vertically disposed in the peripheral wall11bacross the reference surface S and the shaft center O. The inlet port11cis located in the peripheral wall11bat a position between the first mounting leg11dand the second mounting leg11e, and on the upper side of the motor chamber111with respect to the reference surface S and the shaft center O, that is, on the upper side of the vehicle with respect to the reference surface S and the shaft center O.

As illustrated inFIG.3, the first mounting leg11dextends in the right and left direction of the housing body11while projecting upward from the peripheral wall11bin the radial direction of the housing body11. The second mounting leg11eextends in the right and left direction of the housing body11while projecting downward from the peripheral wall11bin the radial direction of the housing body11, The first mounting leg11dand the second mounting leg11ehave a first mounting hole112aand a second mounting hole112b, respectively. The first mounting hole112apenetrates through the first mounting leg11din the right and left direction, and the second mounting hole112bpenetrates through the second mounting leg11ein the right and left direction. It is noted that the shapes and the number of the first mounting legs11dand the second mounting legs11eare suitably designable.

The first mounting leg11dand the second mounting leg11eare fastened to an engine, a frame, or the like (not illustrated) of the vehicle using mounting bolts (not illustrated) inserted through the first mounting hole112aand the second mounting hole112b, respectively. As a result, the first mounting leg11dand the second mounting leg11eattach the housing body11and, eventually, the electric compressor to the engine, frame, or the like of the vehicle. At this time, the electric compressor is mounted in the vehicle with its back and forth direction horizontal. Since the second mounting leg11eis disposed at a position of the peripheral wall11bthat is on the lower side of the vehicle with respect to the reference surface S, the second mounting leg11eis mounted to the vehicle below the first mounting leg11d.

The first mounting leg11dand the second mounting leg11eattach the electric compressor to the engine, frame, or the like of the vehicle, and thus in the electric compressor the upper side of the motor chamber111corresponds to the upper side of the vehicle, and the lower side of the motor chamber111, including the storage area12, corresponds to the lower side of the vehicle. That is, the first mounting leg11dand the second mounting leg11edefine the up and down direction of the motor chamber111and, eventually, the up and down direction of the electric compressor mounted in the vehicle. The inlet port11cis located on the upper side of the vehicle with respect to the reference surface S and the shaft center O, and the storage area12is located on the lower side of the vehicle with respect to the reference surface S and the shaft center O as well as the inlet port11c. The electric compressor is configured not to be able to change its posture independently of the vehicle while being mounted in the vehicle. Therefore, the lubricant oil and liquid refrigerant stored in the storage area12are prevented from flowing toward the inlet port11cand flowing out of the motor chamber111through the inlet port11c.

As illustrated inFIG.1, each bolt hole11fextends in the direction of the shaft center O and is opened at the rear end of the housing body11.

The rear cover13is located on the rear side of the housing body11in the direction of the shaft center O. The rear cover13is fixed to the rear end of the housing body11by a plurality of bolts13ainserted in the respective bolt holes11f. InFIG.1, one of the plurality of bolts13ais illustrated. The rear cover13is formed in a bottomed tubular shape, and with a discharge chamber (not illustrated) therein. The discharge chamber is connected to a condenser through a pipe (not illustrated).

The inverter cover15is located on the front side of the housing body11in the direction of the shaft center O. The inverter cover15is fixed to the front wall11aof the housing body11by a plurality of bolts (not illustrated). The inverter cover15is formed in a bottomed tubular shape, and accommodates the inverter9therein.

As illustrated inFIGS.4and5, the inverter9includes a first inverter side connection terminal9aas a first phase, a second inverter side connection terminal9bas a second phase, and a third inverter side connection terminal9cas a third phase. The inverter9is electrically connected to the electric motor5and, more specifically, a stator5ato be described later by the first to third inverter side connection terminals9ato9cto form a three-phase alternating current. That is, the inverter9and the electric motor5are connected so as to be energized through the three-phase alternating current. The inverter9is electrically connected to a battery (not illustrated) mounted in the vehicle through a power supply connector (not illustrated).

As illustrated inFIGS.1and2, the drive shaft3is disposed inside the housing body11including the motor chamber111. As illustrated inFIG.2, the drive shaft3has a shape of a column extending in the direction of the shaft center O, and a small diameter portion3a, a large diameter portion3b, and a tapered portion3c. The small diameter portion3ais located on the front end side of the drive shaft3. The large diameter portion3bis located in the rear of the small diameter portion3a. The large diameter portion3bis formed to have a diameter larger than that of the small diameter portion3a. The tapered portion3cis located between the small diameter portion3aand the large diameter portion3b. The tapered portion3cis connected at the front end thereof to the small diameter portion3a. The tapered portion3cis connected at the rear end thereof to the large diameter portion3bwhile increasing its diameter toward the rear.

The drive shaft3has the small diameter portion3arotatably supported by a radial bearing19in the front wall11aof the housing body11. Thus, the drive shaft3is rotatable around the shaft center O in the motor chamber111.

The electric motor5is housed in the motor chamber111. The electric motor5includes the stator5aand a rotor5b. The stator5ais fixed to the inner circumferential surface of the peripheral wall11bin the motor chamber111.

As illustrated inFIGS.2and3, the stator5aincludes a stator core50, a first connector51, a second connector52, a third connector53, five first coils54, five second coils55, and five third coils56. In order to facilitate the explanation, a part of the first to third coils54to56is omitted and illustration of the first to third connectors51to53is omitted inFIG.2.

As illustrated inFIG.2, the stator core50is formed in the shape of a cylinder extending backward and forward in the direction of the shaft center O and includes an outer circumferential surface50aand an inner circumferential surface50b. The stator core50is provided with a plurality of slots50c. Each slot50cis recessed from the inner circumferential surface50btoward the outer circumferential surface50a. As illustrated inFIG.3the slots50care disposed at equal intervals in the circumferential direction of the stator core50, and as illustrated inFIG.2, extend from the front end to the rear end of the stator core50in the direction of the shaft center O.

As illustrated inFIG.3the first connector51includes a first connector housing51aand a first lead wire51b. A first connector side connection terminal (not illustrated) is accommodated in the first connector housing51a. A first connection port510is formed in the first connector housing51a. The first lead wire51bis connected, at one end thereof, to the first connector side connection terminal in the first connector housing51aand, at the other end, extends to the outside of the first connector housing51a. Although detailed illustration is omitted, the first lead wire51bis inserted in a tube made of resin. The first connector side connection terminal and a connecting portion between the first lead wire51band the first connector side connection terminal are sealed by the first connector housing51a.

The second connector52and the third connector53have the same structure as the first connector51. That is, the second connector52includes a second connector housing52aand a second lead wire52b, and the third connector53includes a third connector housing53aand a third lead wire53b. A second connection port520and a third connection port530are formed in the second connector housing52aand the third connector housing53a, respectively. The second lead wire52band the third lead wire53bare inserted in respective tubes made of resin.

The first coils54are formed by winding respective first conductor wires57ain the corresponding slots50c. The second coils55are formed by winding respective second conductor wires57bin the corresponding slots50c, The third coils56are formed by winding respective third conductor wires57cin the corresponding slots50c. More specifically, each first coil54is formed by a concentrated winding in which the first conductor wire57ais wound between the adjacent slots50cplural times. Similarly, each second coil55is formed by a concentrated winding in which the second conductor wire57bis wound between the adjacent slots50cplural times, and each third coil56is formed by a concentrated winding in which the third conductor wire57cis wound between the adjacent slots50cplural times. In such a way, the first coils54, the second coils55and the third coils56are independent of each other in the stator5a. The first conductor wire57aforming each first coil54, the second conductor wire57bforming each second coil55, and the third conductor wire57cforming each third coil56have the same structure and are covered with insulating films (not illustrated). As illustrated inFIG.2, a part of each of the first to third coils54to56projecting from the stator core50in the direction of the shaft center O is referred to as a coil end.

Since the slots50care disposed at equal intervals in the circumferential direction of the stator core50, the first to third coils54to56are also disposed at equal intervals in the circumferential direction of the stator core50as illustrated inFIG.3. The first coils54, the second coils55, and the third coils56are disposed one by one in the circumferential direction of the stator core50in the order of the first coil54, the second coil55and the third coil56. It is noted that the number and the size of the first to third coils54to56are suitably designable.

As illustrated inFIG.5, the first coils54are connected to each other in series. In the stator5a, one first coil group540is formed by the five first coils54connected in series. Similarly, the second coils55are connected to each other in series to form one second coil group550. Similarly, the third coils56are connected to each other in series to form one third coil group560.

On one side of the first coil group540, the first conductor wire57ais connected to the first lead wire51bof the first connector51. On one side of the second coil group550, the second conductor wire57bis connected to the second lead wire52bof the second connector52. On one side of the third coil group560, the third conductor wire57cis connected to the third lead wire53bof the third connector53. On the other sides of the first coil group540, the second coil group550and the third coil group560, that is, on the sides of the first through third coil groups540,550and560opposite to the first through third connectors51,52and53, the first conductor wire57a, the second conductor wire57band the third conductor wire57care connected to each other to form a neutral point10.

In the first coil group540, the first coil54connected to the first lead wire51bof the first connector51, that is, of the five first coils54forming the first coil group540, the first coil54directly connected to the first lead wire51bis referred to as a first specific coil54a. Similarly, in the second coil group550, the second coil55directly connected to the second lead wire52bof the second connector52is referred to as a second specific coil55a. In the third coil group560, the third coil56directly connected to the third lead wire53bof the third connector53is referred to as a third specific coil56a.

That is, in the first coil group540, the first specific coil54ais directly connected to the first connector51by connecting to the first lead wire51b, and the other first coils54are indirectly connected to the first connector51via the first specific coil Ma. Similarly, in the second coil group550, the second specific coil55ais directly connected to the second connector52by connecting to the second lead wire52b, and the other second coils55are indirectly connected to the second connector52via the second specific coil55a. In the third coil group560, the third specific coil56ais directly connected to the third connector53by connecting to the third lead wire53b, and the other third coils56are indirectly connected to the third connector53via the third specific coil56a.

As illustrated inFIG.3, the stator5ais fixed in the motor chamber111by fixing the outer circumferential surface50aof the stator core50to the inner circumferential surface of the peripheral wall11b. The stator5ais fixed in the motor chamber111in a state where the first to third specific coils54ato56aof the first to third coils54to56are disposed on the upper side of the motor chamber111with respect to the inlet port11cand the shaft center O, that is, on the upper side of the vehicle with respect to the inlet port11cand the reference surface S. As a result, in the motor chamber111, the first to third specific coils54ato56aare located at positions farther from the storage area12than the inlet port11cand the shaft center O.

On the other hand, some of the first to third coils54to56other than the first to third specific coils54ato56aare disposed in the storage area12to be immersed in the lubricant oil and the liquid refrigerant by fixing the stator5ain the motor chamber111.

While the stator5ais fixed, in the motor chamber111, the first to third connectors51to53are connected to the first to third inverter side connection terminals9ato9cof the inverter9via a connection opening (not illustrated) formed through the front wall11a. Specifically, as illustrated inFIGS.4and5, the first connector51is connected to the first inverter side connection terminal9a, the second connector52is connected to the second inverter side connection terminal9b, and the third connector53is connected to the third inverter side connection terminal9c. In connecting the first connector51to the first inverter side connection terminal9a, the first connector side connection terminal in the first connector housing51ais connected to the first inverter side connection terminal9aby the first connection port510. The same is true of connecting the second and third connectors52and53to the second and third inverter side connection terminals9band9c, respectively. Thus, the first inverter side connection terminal9aand the first coil group540are connected so as to be energized, and the second inverter side connection terminal9band the second coil group550are connected so as to be energized. Similarly, the third inverter side connection terminal9cand the third coil group560are connected so as to be energized.

The first conductor wire57ais electrically connected to the first inverter side connection terminal9avia the first connector51, the second conductor wire57bis electrically connected to the second inverter side connection terminal9bvia the second connector52, and the third conductor wire57cis electrically connected to the third inverter side connection terminal9cvia the third connector53. Thus, in the first coil group540, the first specific coil54ais located electrically closest to the first inverter side connection terminal9a. Similarly, in the second coil group550, the second specific coil55ais located electrically closest to the second inverter side connection terminal9b. Similarly, in the third coil group560, the third specific coil56ais located electrically closest to the third inverter side connection terminal9c.

As illustrated inFIGS.2and3, the rotor5bis disposed in the stator5a. The rotor5bis formed by laminating a plurality of steel plates in the direction of the shaft center O and has a cylindrical shape. The rotor5bis provided with a permanent magnet (not illustrated). The rotor5bis fixed with the large diameter portion3bof the drive shaft3by shrink fit. Thus, the rotor5bis integrally formed with the drive shaft3and rotatable with the drive shaft3around the shaft center O.

As the compression portion7illustrated inFIG.1, a known scroll type compression portion is adopted. The compression portion7includes a fixed scroll that is fixed behind the motor chamber111to the inner circumferential surface of the peripheral wall11bin the housing body11, and a movable scroll that is disposed so as to face the fixed scroll and rotatable by the drive shaft3. The fixed scroll and the movable scroll are meshed with each other to form a plurality of compression chambers therebetween. It is noted that the fixed scroll, the movable scroll, and the compression chambers are not illustrated.

In the electric compressor configured as described above, as illustrated by the broken arrows inFIGS.2and3, low-temperature and low-pressure refrigerant gas that has passed through the evaporator is drawn into the motor chamber111from the inlet port11c. At this time, the refrigerant gas is drawn into the motor chamber111from the position that is on the upper side of the motor chamber111and, eventually, on the upper side of the vehicle with respect to the reference surface S and the shaft center O. The lubricant oil contained in the refrigerant gas is separated from the refrigerant gas in the motor chamber111. Thus, the refrigerant gas from which the lubricant oil has been separated passes through the motor chamber111toward the compression portion7while flowing between the stator5aand the rotor5band between the first to third coils54to56. At this time, the electric motor5and the like are cooled by the refrigerant gas. On the other hand, the lubricant oil that has been separated from the refrigerant gas flows toward the lower side in the vertical direction in the motor chamber111and, eventually, the lower side of the vehicle in the motor chamber111by gravity so as to be stored in the storage area12. In this way, the drive shaft3, the compression portion7, and the like are lubricated by the lubricant oil stored in the storage area12. In addition, part of the refrigerant gas that has been drawn into the motor chamber111is liquefied as a liquid refrigerant and stored in the storage area12with the lubricant oil.

In the electric compressor, the inverter9controls driving the electric motor5while supplying power to the stator5a. Specifically, an alternating current is supplied to each of the first to third coil groups540to560through the first to third inverter side connection terminals9ato9cand the first to third connectors51to53, respectively. That is, an alternating current is supplied to each of the first coils54including the first specific coil54afrom the first inverter side connection terminal9a, and an alternating current is supplied to each of the second coils55including the second specific coil55afrom the second inverter side connection terminal9b. An alternating current is supplied to each of the third coils56including the third specific coil56afrom the third inverter side connection terminal9c. At this time, the phases of the alternating currents supplied from the first to third inverter side connection terminals9ato9care different from each other.

In this way, in the stator5a, the first to third coil groups540to560sequentially generate a magnetic field. Therefore, the rotor5brotates around the shaft center O together with the drive shaft3in the stator core50. In this way, the electric motor5rotates the drive shaft3around the shaft center O, so that the compression portion7operates. Therefore, the refrigerant gas flowing through the motor chamber111toward the compression portion7is introduced into the compression portion7and compressed in the compression chambers. Then, the compressed refrigerant gas is discharged from the discharge chamber to the condenser via an outlet port.

In the electric compressor, a high voltage of about 800 volts is applied to the stator5aby supplying power from the inverter9to the stator5a. In this respect, in the electric compressor, the first to third coils54to56of the stator5aare formed by concentrated winding, and independent of each other. In this way, in the electric compressor, unlike the case where the first to third coils54to56are formed by distributed windings, the first to third coils54to56do not approach each other at the coil end. Thus, even when the above high voltage is applied, partial discharge due to the movement of electrons is less likely to occur in each of the first to third coils54to56. Therefore, in the electric compressor, even if the high voltage is applied, the insulating films of the first to third conductor wires57ato57care less likely to be damaged in the first to third coils54to56.

Further, in the electric compressor, the first coils54are connected in series to form the first coil group540. Similarly, the second coils55are connected in series and the third coils56are connected in series to form the second coil group550and the third coil group560, respectively. In the first to third coil groups540to560, the first to third coils54to56directly connected to the first to third connectors51to53are the first to third specific coils54ato56a, respectively.

In this way, in the first to third coil groups540to560, the first to third coils54to56are connected in series, so that in the electric compressor, when the stator5aand, eventually, the first to third coil groups540to560are energized, in the first coil group540, the potential gradually decreases from the first connector51side and, eventually, the inverter9side toward a connection of the first coil group540to the second and third coil groups550and560, that is, toward the neutral point10. Therefore, in the first coil group540, the voltage applied to the first specific coil54abecomes larger than the voltages applied to the other first coils54, but the voltages applied to the first coils54other than the first specific coil54abecome smaller correspondingly. Further, in the first coil group540, the voltage applied to the first coil54also gradually decreases as the distance from the first specific coil54aincreases, so that the voltage applied to the first coil54closest to the neutral point10becomes the smallest. The same is true of the second coil group550and the third coil group560.

Moisture outside the electric compressor is inevitably mixed in the lubricant oil and the refrigerant gas when the lubricant oil and the refrigerant gas circulate in the pipe, the evaporator, and the like. Therefore, the lubricant oil drawn into the motor chamber111from the inlet port11ctogether with the refrigerant gas and, eventually, the lubricant oil and the liquid refrigerant stored in the storage area12contain moisture.

In this respect, in the electric compressor, the first specific coil54a, the second specific coil55a, and the third specific coil56aare located on the upper side of the motor chamber111with respect to the inlet port11cand the shaft center O in a state where the stator5ais provided in the motor chamber111. That is, in the motor chamber111, the first to third specific coils54ato56aare disposed farther from the storage area12than the inlet port11cand the shaft center O.

Therefore, in the electric compressor, the first to third specific coils54ato56aare difficult to be immersed in the lubricant oil and the liquid refrigerant in the storage area12, and the lubricant oil and the liquid refrigerant in the storage area12are difficult to adhere to the first to third specific coils54ato56a. As a result, in the electric compressor, it is possible to prevent the first to third specific coils54ato56a, which have a high voltage, from being immersed in the lubricant oil and the liquid refrigerant having a reduced volume resistivity due to contamination of moisture. It is also possible to make the first to third specific coils54ato56aless susceptible to the influence of the lubricant oil and the liquid refrigerant with the reduced volume resistivity. In this way, in the electric compressor, even if the voltages in the first to third specific coils54ato56aare relatively high, it is possible to suppress the electric leakage from the first to third conductor wires57ato57c.

On the other hand, in the electric compressor, in the first to third coil groups540to560, the first to third coils54to56other than the first to third specific coils54ato56aare disposed closer to the storage area12than the first to third specific coils54ato56a. Therefore, part of the first to third coils54to56other than the first to third specific coils54ato56ais immersed in the lubricant oil and the liquid refrigerant in the storage area12, that is, the lubricant oil and the liquid refrigerant mixed with moisture. However, as described above, the voltages applied to the first to third coils54to56other than the first to third specific coils54ato56aare smaller than the voltage applied to the first to third specific coils54ato56a. Therefore, even if the first to third coils54to56other than the first to third specific coils54ato56aare immersed in the lubricant oil and the liquid refrigerant, it is possible to suppress the electric leakage from the first to third conductor wires57ato57c.

Further, in the electric compressor, the first to third connectors51to53may be immersed in the lubricant oil and the liquid refrigerant in the storage area12, but in the first to third connectors51to53, the first to third connector side connection terminals and the connection portions between the first to third connector side connection terminals and the first to third lead wires51bto53bare sealed by the first to third connector housings51ato53a. Therefore, even if the first to third connectors51to53are immersed in the lubricant oil and the liquid refrigerant in the storage area12, electric leakage from the first to third connectors51to53is suppressed.

Therefore, the electric compressor of the embodiment exhibits excellent durability while coping with high voltage.

In particular, in the electric compressor, the first to third connector housings51ato53aseal the first to third connector side connection terminals and the connection portions between the first to third connector side connection terminals and the first to third lead wires51bto53bto thereby suppress the occurrence of electric leakage from the first to third connectors51to53caused by the lubricant oil and the liquid refrigerant. Therefore, in the electric compressor, as compared with the case where the first to third coils54to56including the first to third specific coils54ato56aare additionally coated or the like to prevent the occurrence of electric leakage from the first to third coils54to56caused by the lubricant oil and the liquid refrigerant, it is possible to facilitate manufacture of the stator5a. As a result, the manufacturing cost of the electric compressor is reduced.

In the electric compressor, the amount of lubricant oil, the size of the motor chamber111, and the like are designed so that the liquid level of the lubricant oil and the liquid refrigerant stored in the storage area12does not exceed the inlet port11cand the shaft center O. Further, the electric compressor is configured such that the posture cannot be changed independently of the vehicle in the state of being attached to the vehicle by the first and second mounting legs11dand11e. For these configurations, in the electric compressor, the situation where the liquid level of the lubricant oil and the liquid refrigerant stored in the storage area12is located above the inlet port11cin the vertical direction, that is, on the upper side of the motor chamber111seldom occurs.

In the electric compressor, the first specific coil54a, the second specific coil55a, and the third specific coil56aare located on the upper side of the motor chamber111and, eventually, on the upper side of the vehicle with respect to the inlet port11c. As described above, in the electric compressor, it is preferably avoided that the first to third specific coils54ato56aare immersed in the lubricant oil and the liquid refrigerant, and as a result, the electric leakage from the first to third conductor wires57ato57cis suitably prevented.

In the above, the present disclosure has been described in accordance with the embodiment, but it goes without saying that the present disclosure is not limited to the above embodiment and can be appropriately modified and applied without departing from the spirit of the present disclosure.

For example, the first to third connectors51to53may be connected to the first to third inverter side connection terminals9ato9cof the inverter9at positions that are on the upper side of the motor chamber111with respect to the inlet port11cand the shaft center O. In this case, in addition to the first to third specific coils54ato56a, the first to third connectors51to53are also disposed away from the storage area12, so that it is possible to more preferably prevent the occurrence of electric leakage caused by the lubricant oil and the liquid refrigerant for the first to third connectors51to53.

Further, as the compression portion7, a vane type compression portion, a swash plate type compression portion, or the like may be adopted.

Further, the inlet port11cmay be formed on the upper side of the motor chamber111with respect to the first to third specific coils54ato56a. Further, the inlet port11cmay be formed on the lower side of the motor chamber111with respect to the reference surface S and the shaft center O.

The present disclosure may be used for air conditioners for vehicles or the like.

An electric compressor of the present disclosure includes a housing, a drive shaft, an electric motor, a compression portion, and an inverter. The electric motor is configured to rotate the drive shaft. The compression portion is configured to be driven by the drive shaft to compress refrigerant. The inverter includes a first phase, a second phase, and a third phase that are electrically connected to the electric motor to form a three-phase alternating current. The inverter controls driving the electric motor. The housing includes a motor chamber that houses the electric motor and through which refrigerant passes. The electric motor includes a stator that is fixed to the housing and disposed in the motor chamber, and a rotor to which the drive shaft is fixed. The rotor is disposed in the stator and rotatable with the drive shaft. The stator includes: a stator core that has a tubular shape and extends in a direction of a shaft center of the drive shaft; a plurality of first coils formed by winding, to the stator core, a first conductor wire that is electrically connected to the first phase; a plurality of second coils formed by winding, to the stator core, a second conductor wire that is electrically connected to the second phase; and a plurality of third coils formed by winding, to the stator core, a third conductor wire that is electrically connected to the third phase. The first coils are connected to each other in series, the second coils are connected to each other in series, and the third coils are connected to each other in series. One of the first coils that is located electrically closest to the first phase is referred to as a first specific coil, one of the second coils that is located electrically closest to the second phase is referred to as a second specific coil, and one of the third coils that is located electrically closest to the third phase is referred to as a third specific coil. The first specific coil, the second specific coil, and the third specific coil are disposed above the shaft center of the drive shaft.

In the electric compressor of the present disclosure, since the refrigerant passes through the motor chamber, it is possible to cool the electric motor with the refrigerant. On the other hand, the lubricant oil contained in the refrigerant and the liquid refrigerant may be stored in the motor chamber. The lubricant oil and the liquid refrigerant are stored on the lower side in a vertical direction in the motor chamber by gravity. Since moisture is inevitably mixed in the lubricant oil and the liquid refrigerant, the volume resistivity is lower than that in the case where moisture is not mixed.

Further, in the electric compressor, the first coils are connected in series. Similarly, the second coils are also connected in series and the third coils are also connected in series. Then, each first coil is electrically connected to the first phase, each second coil is electrically connected to the second phase, and each third coil is electrically connected to the third phase.

If the first coils are connected in parallel and each first coil is energized from the first phase, the voltage in each first coil becomes equal. Therefore, if a high voltage is applied to each of the first coils from the first phase, the high voltage is equally applied to all the first coils. On the other hand, when the first coils are connected in series and each first coil is energized from the first phase, the voltage in the first coil electrically closest to the first phase in the first coils, that is, the voltage in the first specific coil located on the most upstream side in the first coils in the feeding direction from the first phase to each first coil is larger than the voltages in the first coils other than the first specific coil. In other words, the voltages applied to the first coils other than the first specific coil are smaller than that in the first specific coil. According to the inventors' verification, about 70% to 80% of the total voltage applied from the first phase to the first coils is applied to the first specific coil, and the remaining 20% to 30% of the voltage is applied to the first coils other than the first specific coil. Further, as the distances from the first specific coil to the first coils increase, the voltages applied to the first coils also gradually decrease. The same is true of the second coils and the third coils.

In the electric compressor, the first specific coil, the second specific coil, and the third specific coil are disposed above the shaft center in a state where the stator is provided in the motor chamber. That is, the first to third specific coils are located above the shaft center in the vertical direction in the motor chamber. Therefore, in the electric compressor, it is difficult for the first to third specific coils to be immersed in the lubricant oil and the liquid refrigerant stored in the motor chamber. As a result, even if the voltage in the first specific coil is relatively high, electric leakage from the first conductor wire is suppressed. The same is true of the second and third specific coils to suppress electric leakage from the second and third conductor wires, respectively. Although the electric leakage from the first to third conductors, that is, the electric leakage from the first to third specific coils is likely to occur through the moisture separated from the stored lubricant oil and liquid refrigerant, such moisture originally exists outside the electric compressor, and is mixed with the lubricant oil and the liquid refrigerant. Therefore, it is generally difficult to think that a large amount of moisture, in which the amount of the separation exceeds the shaft center in the motor chamber, is mixed with the lubricant oil and the liquid refrigerant. Therefore, if the first to third specific coils are located above the shaft center, the occurrence of the above-mentioned electric leakage is sufficiently suppressed.

In the electric compressor, on the other hand, the first to third coils other than the first to third specific coils may be immersed in the lubricant oil and the liquid refrigerant. However, as described above, the voltages applied to the first to third coils other than the first to third specific coils are smaller than that in the first to third specific coils. Therefore, it is possible to suppress electric leakage from the first to third conductors of the first to third coils that are immersed in the lubricant oil and the liquid refrigerant.

Accordingly, the electric compressor of the present disclosure exhibits excellent durability while coping with high voltage.

The housing may include an inlet port that is located above the shaft center of the drive shaft and provides communication between an outside of the housing and the motor chamber. In addition, it is preferable that the first specific coil, the second specific coil, and the third specific coil are disposed above the inlet port.

In this case, the refrigerant is drawn into the motor chamber through the inlet port. If the lubricant oil and the liquid refrigerant are to be stored beyond the position of the inlet port in the motor chamber, the lubricant oil and the liquid refrigerant will be discharged to the outside of the housing through the inlet port. Therefore, it is difficult that the liquid level of the lubricant oil and the liquid refrigerant stored in the motor chamber exceeds the position of the inlet port. As a result, since the first to third specific coils are located above the inlet port, the first to third specific coils are less likely to be immersed in the lubricant oil and the liquid refrigerant. Therefore, in the electric compressor, it is possible to suitably prevent electric leakage from the first to third conductor wires, so that the durability is further improved.

The electric compressor of the present disclosure may be mounted in a vehicle. In addition, it is preferable that the housing includes a mounting portion that is fixed to the vehicle to define an up and down direction of the motor chamber with the electric compressor mounted in the vehicle. In this case, the mounting portion allows the housing, and thus the electric compressor, to be suitably fixed to the vehicle. Further, since the first to third specific coils are located above the shaft center, the first to third specific coils are less likely to be immersed in the lubricant oil and the liquid refrigerant.