Hermetic compressor

Abstract

 A cooling system for an electric compressor for vehicle use is disclosed. The system comprises an electric compressor having a motor housed within a closed container and a compression element driven by said motor which compresses a refrigerant gas drawn from the exterior of said closed container and thereafter discharges it to the exterior of said closed container, and heat exchanging means arranged to establish a heat exchanging relationship with an engine cooling system of the vehicle. The refrigerant gas discharged from said compression element flows to said heat exchanging means and returns to the said motor side within said closed container and thereafter is discharged to the exterior of said closed container.

Description

[0001] The present invention relates to a horizontal closed type compressor for vehicle use provided with oil supply means for feeding lubricating oil to a compression element and also a cooling system for an electric compressor for vehicle use provided with heat exchanging means arranged to exchange heat with the engine cooling system of a vehicle.

[0002] A horizontal closed type compressor is known, for example, from Japanese Unexamined Patent Publication No. 7-229660 (F25B43/00) which comprises a motor housed in a closed container which drives a rotary shaft in a lateral direction, and a compression element such as a rotary compressor, scroll compressor or the like driven by the motor. Lubricating oil is stored within the closed container. An oil suction pipe is located opposite the motor element, and an oil pump sucks lubricating oil through the oil suction pipe and circulates it around a cylinder of the compression element and a bearing frame, thereby preventing the horizontal closed type compressor from being abraded.

[0003] In recent years, air conditioning systems used in cars or other types of motor vehicles generally use a horizontal closed type compressor. However, when the vehicle travels up a mountain, slope or the like, the closed container becomes inclined and one side of the oil pump or the oil suction pipe becomes higher than the motor. When this happens, lubricating oil stored within the closed container moves to the side of the motor opposite the oil suction pipe under the force of gravity so part of the top surface of the lubricating oil is lower than the oil suction pipe, so the oil pump cannot suck the lubricating oil through the oil suction pipe and lubricating performance is therefore reduced. Accordingly, there has been a need to develop a horizontal closed type compressor for vehicle use which can suck the lubricating oil from the oil suction pipe without the oil surface of the lubricating oil becoming lower than the oil suction pipe, even if the vehicle and thus the compressor is inclined.

[0004] Furthermore, in recent years, car air-conditioners mounted on most vehicles have a pipe in the discharge side of the compressor (e.g. a rotary compressor, a scroll compressor or the like) connected to a radiator, the outlet side of the condenser being connected to a liquid receiver. A pipe on the outlet side of the liquid receiver is connected to a pressure reducing apparatus which is connected to the pipe in the suction side of the compressor via an evaporator (a cooling device) to provide the refrigerant circuit.

[0005] When the compressor is driven, a gas refrigerant at high temperature and pressure is discharged from the compressor and flows into the radiator where the refrigerant radiates heat, condenses and liquefies. The condensed and liquefied refrigerant then flows into the liquid receiver where it is stored. The liquid refrigerant then passes to the pressure reducing apparatus where it is compressed and thereafter it flows into the evaporator. The refrigerant flowing into the evaporator evaporates there, and absorbs heat from the environment at that time, thereby achieving a cooling effect. In the refrigerant coming out of the evaporator, non-evaporated liquid refrigerant is separated into vapor and liquid and thereafter only the gas refrigerant is sucked to the compressor. This circulation is then repeated.

[0006] In a car air-conditioner mounted on a vehicle, the radiator for the rotary compressor, the scroll compressor or the like, is usually mounted in the engine compartment where it radiates heat and this can be because of the limited space in the engine compartment.

[0007] Placing the electric compressor in the engine compartment means that is subjected to the high temperatures generated therein by the engine so it is unavoidable that the temperature of the motor element, the lubricating oil or the like is increased, and the cooling capacity of the electric compressor for vehicle use is thereby reduced.

[0008] The present invention solves or substantially reduces the problems in the prior art discussed above, and it is an object of the present invention to provide a horizontal closed type compressor for vehicle use which can suck a lubricating oil from an oil suction pipe without the surface level of the lubricating oil becoming lower than the oil suction pipe, even when the vehicle, and hence the compressor, is inclined.

[0009] Another object of the present invention is to provide a cooling system for an electric compressor for vehicle use which can prevent the temperature of the motor and lubricating oil from increasing, and can function efficiently in an engine compartment having limited space.

[0010] In accordance with the present invention, there is provided a horizontal closed type compressor for vehicle use comprising a motor housed in a closed container to drive a rotary shaft in a lateral direction, a compression element driven by the motor, lubricating oil received in the closed container, and oil supply means for feeding the lubricating oil to the compression element, the oil supplying means being provided on an opposite side of the compression element to the motor, wherein the compression element compresses refrigerant gas drawn from the exterior of the closed container and discharges it into the motor element side of the closed container, and thereafter out of the closed container from the side of the oil supply means. Partition walls divide the interior of the closed container to allow the refrigerant gas and the lubricating oil to move therethrough. The partition walls are respectively provided on the motor side and the oil supplying means side of the compression element.

[0011] In accordance with the present invention, since the pressure in the motor side within the closed container, divided by the partition wall, is higher than that in the oil-supplying means side, for example, even in the case that the oil supplying means side of the compressor is higher due to the vehicle being inclined, it is possible to prevent the lubricating oil stored in the side of the oil supplying means from flowing to the motor side as the partition wall acts as a barrier. Accordingly, it is possible to limit a drop in the level of the lubricating oil stored in the oil supplying means side within the closed container, and hence prevent a reduction in the lubricating performance. Accordingly, since a predetermined amount of lubricating oil can be stored in the oil supplying means side within the closed container, even when the compressor is inclined, oil can still be supplied from the inner portion of the oil supplying means within the closed container to the cylinder and the bearing frame.

[0012] Preferably, an external pipe is provided on the closed container for discharging the refrigerant gas from the compression element to the motor side of the closed container. This makes it possible to cool the high temperature refrigerant gas discharged from the compression element by passing it through the external pipe. Thus, even if a refrigerant such as a carbon dioxide is used, and the temperature of the horizontal closed type compressor is increased, it is possible to significantly improve the cooling efficiency of the refrigerant discharged from the compressor.

[0013] Preferably, the compression element comprises a plurality of rotary compression elements provided between both of the partition walls. This allows the space between the partition walls to be set so that the pressure on the motor side is high, the pressure on the oil supplying means side is low and, an intermediate pressure can be easily generated in the middle. Thus, it is possible to store the lubricating oil in the oil supplying means side due to the pressure difference between the respective partition walls. Therefore, even if the compressor is inclined, it is possible to store a predetermined amount of lubricating oil in the oil storage portion, so oil can be continually supplied from the inner portion of the oil storage portion to the cylinder and the bearing frame thereby significantly improving lubricating performance.

[0014] The present invention also provides a cooling system for an electric compressor for vehicle use comprising an electric compressor having a motor housed within a closed container and a compression element driven by the motor which compresses a refrigerant gas drawn from the exterior of the closed container and thereafter discharging it to the exterior of said closed container and heat exchanging means arranged to establish a heat exchanging relationship with an engine cooling system of the vehicle, wherein the refrigerant gas discharged from the compression element flows to the heat exchanging means and returns to the motor side within the closed container and thereafter is discharged to the exterior of the closed container.

[0015] Preferred embodiments of the invention will now be described, by way of example only, with reference to the accompanying drawings, in which:

Figure 1 is a vertical cross sectional side view of a horizontal closed type compressor for vehicle use in accordance with the present invention having a two-cylinder rotary compressor provided with first and second rotary compression elements;

Figure 2 is a vertical cross sectional side view of the two-cylinder rotary compressor shown in Figure 1 in which one side of the oil pump is higher than a side of the motor;

Figure 3 is a vertical cross sectional side view of the two-cylinder rotary compressor shown in Figure 1 in which one side of the motor is higher than the side of the oil pump;

Figure 4 is a vertical cross sectional side view of another embodiment of horizontal closed type compressor for vehicle use having a two-cylinder rotary compressor which is provided with first and second rotary compression elements;

Figure 5 is a vertical cross sectional side view of the two-cylinder rotary compressor shown in Figure 4 in which one side of the oil pump is higher than a side of the motor;

Figure 6 is a vertical cross sectional side view of the two-cylinder rotary compressor shown in Figure 4 in which one side of the motor is higher than a side of the oil pump,

Figure 7 is a vertical cross sectional side view of another embodiment of a horizontal closed type compressor for vehicle use having a one-cylinder rotary compressor which is provided with single rotary compression elements;

Figure 8 is a vertical cross sectional side view of the one-cylinder rotary compressor shown in Figure 7 in which one side of the oil pump is higher than a side of the motor;

Figure 9 is a vertical cross sectional side elevational view of the one-cylinder rotary compressor shown in Figure 7 in which one side of the motor element is higher than a side of the oil pump; and

Figure 10 is a vertical cross sectional side view of a two-cylinder rotary compressor which is provided with first and second rotary compression elements corresponding to an embodiment of horizontal closed type compressor for vehicle use in accordance with an invention described in the fourth and fifth aspects.

[0016] Referring to the drawings, there is shown a rotary compressor 1 and refrigerant circuit for an air conditioning system for the passenger compartment of a motor vehicle (not shown) which is horizontally mounted, for example, within the engine compartment of said motor vehicle. The rotary compressor 1 comprises a cylindrical closed container 4 made of steel plate with a motor 6 housed therein. A compressor 8 comprising a first rotary compression element 2 and a second rotary compression element 3 driven by rotatable shaft 7 is mounted in the container 4.

[0017] A predetermined amount of carbon dioxide gas is charged as a refrigerant within the closed container 4, together with a predetermined amount of lubricating oil (OL) such as polyalkylene glycol (PAG). However, the lubricating oil (OL) may be a poly alpha olein (PAO) or a mineral oil.

[0018] In the illustrated embodiment, the closed container 4 comprises a container main body 4A housing the motor 6 and the compressor element 8, and a bowl-like end cap 4B closing the open end of the container main body 4A, a terminal (wiring omitted) 11 for supplying electric power to the motor 6 being provided in the end cap 4B. A space 12 for storing lubricating oil is provided within the end portion of the closed container 4 opposite the motor 6.

[0019] The motor 6 comprises a stator 22 mounted on the inner surface of the container main body 4A with a rotor 24 located inside it. The rotor 24 is fixed to the shaft 7 which extends in a horizontal direction through the centre thereof.

[0020] The stator 22 has a stator core 26 constructed of laminated ring-like electromagnetic steel plates, and a stator coil 28 wound around the stator core 26. The rotor 24 is formed of a core 30 made of an electromagnetic steel plate and a permanent magnet inserted into an inner portion thereof in the same manner as that of the stator 22, whereby a brushless DC motor is constituted by both elements.

[0021] A partition 36 is mounted between the first rotary compression element 2 and the second rotary compression element 3 with cylinders 38 and 40 on either side thereof. Left and right rollers 46 and 48 are positioned within the cylinders 38 and 40 and fitted to left and right eccentric portions 42 and 44 provided on the shaft 7 with a phase difference of 180 degrees so as to eccentrically rotate, vanes (not shown) brought into contact with the left and right rollers 46 and 48 and respectively divide inner portions of the left and right cylinders 38 and 40 into low and high pressure chambers. A main frame (a left bearing) 51 and an auxiliary frame (a right bearing) 52 close the respective opening surfaces of the left and right cylinders 38 and 40 and also serve as the bearing of the shaft 7.

[0022] A suction passage 53 is formed within the cylinder 38 and connected to a suction pipe 54 mounted on the closed container 4. The suction pipe 54 is connected to a cooler (not shown) for cooling the vehicle passenger compartment. A series of branch suction passages 56 connected to the suction passage 53 are formed within the intermediate partition plate 36 and the cylinder 40. A muffler cover 57 is mounted to the main frame 51, and a sound reduction chamber 58 for the inner portion of the cylinder 38 is thereby formed within the muffler cover 57. A muffler cover 59 is mounted to the auxiliary frame 52 on sound reduction chamber 61 for the inner portion of the cylinder 40.

[0023] The sound reduction chamber 61 is connected to the interior of the sound reduction chamber 58 by a passage 62 extending through the cylinders 38 and 40 and the partition plate 36, and the sound reduction chamber 58 is connected to the interior of the closed container 4 on the motor 6 side by a discharge port (not shown) formed in the muffler cover 57.

[0024] An oil pump 66 is connected to oil supply means provided in the end portion of the auxiliary frame 52 remote from the motor 6, and an oil suction pipe 67 extends from the oil pump 66 downwardly into the oil storage cavity 12, the lower end thereof being open. A discharge pipe 71 is mounted on an upper portion of the closed container 4 on the opposite side to the motor 6 and the oil storage cavity 12 of the cylinder 40.

[0025] Partition walls 72 and 73 are provided on the motor 6 side and oil storage cavity 12 side of the compressor 8 respectively. The partition wall 72 is mounted to the muffler cover 57 (however, it may alternatively be mounted to the main frame 51 or the cylinder 38), and divides the interior of the closed container 4 into a motor 6 side, and a compressor 8 side, while allowing a movement of the refrigerant gas and the lubricating oil. The partition wall 73 is mounted to the cylinder 40 but it may alternatively be mounted to the auxiliary frame 52 or the muffler cover 59, and divides the interior of the closed container 4 into a compressor 8 side, and an oil storage cavity 12 side, while allowing the movement of the refrigerant gas and the lubricating oil. The discharge pipe 71 is positioned in the oil storage cavity 12 of the partition wall 73.

[0026] In the structure mentioned above, when an electric current is applied to the coil 28 of the motor 6 via the terminal 11 and wiring (not shown), the rotor 24 rotates and the left and right rollers 46 and 48 fitted to the left and right eccentric portions 42 and 44 on the shaft 7 eccentrically rotate within the left and right cylinders 38 and 40.

[0027] Accordingly, refrigerant gas is sucked through the suction pipe 54 into the low pressure chamber side of the cylinder 38 via the suction passage 53, and is sucked into the lower pressure chamber side of the cylinder 40 via the branch suction passage 56. The low pressure refrigerant gas is compressed to a high temperature and pressure by the rollers 46 and 48 and the vane and it reaches the sound reduction chamber 58 from the high pressure chamber side of the cylinder 38, thereby being discharged within the closed container 4 in the motor 6 side from the discharge port. The refrigerant gas reaches the sound reduction chamber 58 from the high pressure chamber side of the cylinder 40 via the sound reduction chamber 61 and the connecting passage 62, and is discharged into the closed container 4 from the discharge port.

[0028] As described above, the refrigerant gas high temperature and pressure is discharged into the motor 6 side of the closed container 4 and reaches the oil storage cavity 12 in the closed container 4 through the gap formed between the respective cylinders 38 and 40 of the compression element 8 and the partition wall 73 so as to be discharged into the external portion from the discharge pipe 71.

[0029] Accordingly, a pressure distribution within the closed container 4 is achieved whereby the motor side of the partition wall 72 has the highest high pressure HH, the intermediate partition plate 36 portion of the compression element 8 between the partition walls 72 and 73 has the middle high pressure HM which is lower than HH, and the side of the oil storage portion 12 of the partition wall 73 in the discharge pipe 71 has the lowest high pressure HL.

[0030] The oil pump 66 is rotated by the shaft 7 and sucks lubricating oil within the oil storage cavity 12 from the lower end opening of the oil suction pipe 67. The lubricating oil I is supplied to the sliding portions within the respective cylinders 38 and 40, and to the sliding portions between the respective frames 51 and 52 and the rotary shaft 7 through the shaft 7.

[0031] As described above, due to the pressure distribution within the closed container 4 being such that the motor 6 side of the partition wall 72 has the highest high pressure HH, the space between partition walls 72 and 73 has a middle high pressure HM, and the oil storage cavity 12 has the lowest high pressure HL, the lubricating oil within the closed container 4 can be held in the oil storage cavity 12 (the side of the oil pump 66). Accordingly, lubricating oil stored in the oil storage cavity 12 is prevented from flowing to the motor 6 by both of the partition walls 73 and 72. Therefore, the oil pump 66 can continuously supply lubricating oil sucked from the interior of the oil storage cavity 12 to the cylinders 38 and 40 and the main frame (the left bearing) 51 and the auxiliary frame (the right bearing) 52 serving as the bearings for the shaft 7.

[0032] A description will now be given with reference to Figure 2 of a two-cylinder rotary compressor in which the oil pump 66 side is higher than the motor 6 as the horizontal closed type compressor 1 for vehicle use is inclined. The closed container 4 is inclined at an angle (about 30 degrees). In this case, lubricating oil stored in the oil storage cavity 12 having the discharge pipe 71 connected thereto is going to move under gravity towards the motor 6 through the gap formed among the partition wall 73, the respective cylinders 38 and 40 and the partition wall 72. However, since the pressure distribution of the high pressure refrigerant discharged within the closed container 4 is such that the motor 6 side of the partition wall 72 has the higher high pressure HH, the space between partition walls 72 and 73 has a middle high pressure HM, and the oil storage cavity 12 has the lower high pressure HL, the lubricating oil stored in the oil storage cavity 12 is prevented from flowing out towards the motor 6 due to the pressure difference generated by both of the partition walls 73 and 72.

[0033] Accordingly, even in the case that the horizontal closed type compressor mounted on the vehicle is inclined so that the oil pump 66 is higher than the motor element 6 side (the opposite side to the oil pump 66), the level of the lubricating oil stored in the oil pump 66 end of the closed container 4 is prevented from dropping thus preventing a reduction in lubricating performance. It is therefore possible to store a predetermined amount of lubricating oil in the oil storage cavity 12. Even in the case that the oil pump 66 in the closed container 4 is inclined to become higher, it is possible to store a small amount of lubricating oil in the motor 6 side of the partition wall 72 having the higher high pressure HH, and store most of the lubricating oil in the oil storage cavity 12 (the side of the oil pump 66) corresponding to the right side of the partition wall 73 having the lower high pressure HL. Accordingly, the oil pump 66 can continuously supply the lubricating oil sucked from the inner portion of the oil storage cavity 12 to the cylinders 38 and 40 and the main frame (the left bearing) 51 and the auxiliary frame (the right bearing) 52 serving as the bearing of the rotary shaft 7.

[0034] A description will now be given with reference to Figure 3 of a two-cylinder rotary compressor 1 in which the motor 6 is higher than the oil pump 66 as the horizontal closed type compressor for vehicle use is inclined. The closed container 4 is inclined at an angle (about 30 degrees). In this case, the lubricating oil is stored within the oil storage cavity 12 and does not flow to the motor 6 due to the gravitational force.

[0035] Accordingly, if the horizontal closed type compressor mounted on the vehicle is inclined so that the motor 6 is higher than the oil pump 66, it is possible to store a predetermined amount of lubricating oil in the oil storage cavity 12. Accordingly, the oil pump 66 can continuously supply lubricating oil sucked from the interior of the oil storage cavity 12 to the cylinders 38 and 40, and the main frame (the left bearing) 51 and the auxiliary frame (the right bearing) 52 serving as the bearing of the shaft 7.

[0036] Figure 4 shows another horizontal closed type compressor for vehicle use in which a two-cylinder rotary compressor is provided with the first and second rotary compression elements 2 and 3. In this compressor, an external pipe 64 is provided for discharging the refrigerant gas at high temperature and pressure, from the compressor 8 to the motor 6. That is, the horizontal closed type compressor for vehicle use is structured such that on the basis of the rotary compressor 1 mentioned above, the external pipe 64 is connected to a discharge port (not shown) formed in the muffler cover 57. The pipe 64 extends to the exterior of the closed container 4 from the discharge port and is connected to the interior of the closed container 4 via the terminal 11 adjacent the motor 6.

[0037] The oil pump 66 is provided in the end portion of the auxiliary frame 52 for the shaft 7 in the same manner as mentioned above. The oil suction pipe 67 provided in the oil pump 66 extends downwardly into the oil storage cavity 12, and the lower end of the oil suction pipe 67 opens into said oil storage cavity 12. Further, the discharge pipe 71 is mounted to the upper portion of the closed container 4 at the opposite end to the motor 6 adjacent the oil storage cavity 12. The other structures are the same as those of the rotary compressor 1 described above.

[0038] In accordance with the structure described above, when electric current is applied to the coil 28 of the motor 6 via the terminal 11 and wiring (not shown), the rotor 24 rotates and the left and right rollers 46 and 48 fitted to the left and right eccentric portions 42 and 44 integrally provided on the shaft 7, eccentrically rotate within the left and right cylinders 38 and 40.

[0039] Accordingly, refrigerant gas is sucked through the suction pipe 54 into the low pressure chamber of the cylinder 38 via the suction passage 53, and into the lower pressure chamber of the cylinder 40 via the branch suction passage 56. The refrigerant gas is compressed by the roller 46, the roller 48 and the vane, to a high temperature and pressure and reaches the sound reduction chamber 58 from the high pressure chamber of the cylinder 38, whereby it is discharged through the external pipe 64 from the discharge port. The refrigerant gas reaches the sound reduction chamber 58 from the high pressure chamber of the cylinder 40 via the sound reduction chamber 61 and the connecting passage 62, and is discharged through the external pipe 64 from the discharge port.

[0040] The high temperature and pressure refrigerant gas is discharged through the external pipe 64 from the discharge port within the closed container 4 (on the side of the motor 6) after being heat exchanged with the ambient air within the external pipe 64 provided outside the closed container 4 and cooled. The refrigerant gas reaches the oil storage cavity 12 within the closed container 4 while cooling the motor 6 or cylinders 38 and 40 or the like becoming high temperature, in the step of passing through the gap formed among the closed container 4, the partition wall 72, the respective cylinders 38 and 40 of the compression element 8 and the partition wall 73 so as to be discharged into the external portion from the discharge pipe 71.

[0041] Accordingly, a pressure distribution within the closed container 4 is made so that the motor 6 side of the partition wall 72 has the highest high pressure HH, the intermediate partition plate 36 portion of the compression element 8 between the partition walls 72 and 73 has a middle pressure HM lower than HH, and the oil storage cavity 12 side of the partition wall 73 in the discharge pipe 71 has the lowest high pressure HL.

[0042] The oil pump 66 is rotated by the shaft 7 to suck lubricating oil from the oil storage cavity 12 via the lower end opening of the oil suction pipe 67. The lubricating oil is supplied to the sliding portions within the respective cylinders 38 and 40 and the sliding portions between the respective frames 51 and 52 and the rotary shaft 7 through the shaft 7.

[0043] Since the pressure distribution within the closed container 4 is such that the motor 6 side of the partition wall 72 has the higher high pressure HH, the space between the partition walls 72 and 73 has a middle high pressure HM, and the oil storage cavity 12 has the lower high pressure HL, the lubricating oil can be held in the oil storage cavity 12. Therefore, the lubricating oil stored in the oil storage cavity 12 is prevented from flowing out to the motor 6 side by the partition walls 73 and 72. Hence, the oil pump 66 can continuously supply lubricating oil to the cylinders 38 and 40 and the main frame (the left bearing) 51 and the auxiliary frame (the right bearing) 52 serving as the bearing of the shaft 7 while preventing the rotary compressor 1 from being heated.

[0044] A description will now be given, with reference to Figure 5, of a two-cylinder rotary compressor in which the oil pump 66 is higher than the motor 6, as the horizontal closed type compressor 1 for vehicle use is inclined. The closed container 4 is inclined at an angle, (about 30 degrees). Lubricating oil stored in the oil storage cavity 12 of the partition wall 73 having the discharge pipe 71 moves under gravity towards the motor 6 through the gap formed among the partition wall 73, the respective cylinders 38 and 40 and the partition wall 72. However, since the pressure distribution within the closed container 4 is such that the motor 6 side of the partition wall 72 has the higher high pressure HH, the space between the partition walls 72 and 73has the middle high pressure HM, and the oil storage cavity 12 has the lower high pressure HL while cooling the motor 6 or the respective cylinders 38 and 40 by the high pressure refrigerant cooled within the external pipe 64, the lubricating oil stored in the oil storage cavity 12 is prevented from flowing out to the motor 6 side due to the pressure difference within the closed container 4 generated by both of the partition walls 73 and 72 while preventing the rotary compressor 1 from being heated. Even if the oil pump 66 side of the closed container 4 is inclined to be higher, it is possible to store a small amount of lubricating oil in the motor 6 side of the partition wall 72 having the higher high pressure HH and store most of the lubricating oil in the oil storage cavity 12 (the oil pump 66 side) corresponding to the right side of the partition wall 73 having the lower high pressure HL.

[0045] Accordingly, even the temperature of the rotary compressor 1, using carbon dioxide as the refrigerant, is increased, it is possible to improve the cooling efficiency of the refrigerant discharged from the compressor. Furthermore, even if the horizontal closed type compressor mounted on the vehicle is inclined so that the oil pump 66 becomes higher than the motor 6, it is possible to restrict the drop in the level of the lubricating oil stored in the oil pump 66 side and hence prevent the lubricating performance from being reduced. It is also possible to store a predetermined amount of lubricating oil in the oil storage cavity 12. Therefore, the oil pump 66 can continuously supply lubricating oil sucked from the interior of the oil storage cavity 12 to the cylinders 38 and 40 and the main frame (the left bearing) 51 and the auxiliary frame (the right bearing) 52 serving as the bearing of the shaft 7 while preventing the rotary compressor 1 from being heated.

[0046] A description will now be given, with reference to Figure 6, of a two-cylinder rotary compressor 1 in which the motor 6 is higher than the oil pump 66 of the horizontal closed type compressor for vehicle use. The closed container 4 is inclined at an angle (about 30 degrees). By making the motor 6 side higher, lubricating oil is stored within the oil storage cavity 12 and does not flow towards the motor 6 under gravity. Since the pressure distribution within the closed container 4 is structured such that the motor 6 side of the partition wall 72 has the higher high pressure, the space between the partition walls 72 and 73 has the middle high pressure HM and the oil storage cavity 12 has the lower high pressure HL, lubricating oil stored in the oil storage cavity 12 is prevented from flowing the motor 6 by the partition walls 73 and 72.

[0047] Accordingly, even if the horizontal closed type compressor mounted on the vehicle is inclined so that the motor 6 becomes higher than the oil pump 66 lubricating oil can still be supplied from the oil storage cavity 12 to the cylinders 38 and 40, and the main frame (the left bearing) 51 and the auxiliary frame (the right bearing) 52 serving as the bearing of the shaft 7 while preventing the rotary compressor 1 from being heated.

[0048] Figure 7 shows a single-cylinder rotary compressor 80 provided with a single rotary compression element 81 corresponding to an embodiment of the horizontal closed type compressor for vehicle use. In this case, the rotary compression element of the horizontal closed type compressor comprising a rotary compressor having one cylinder, a refrigerant circuit of an air-conditioning system for a passenger compartment of a motor vehicle (not shown) in the same manner as that mentioned above, and is horizontally mounted within the engine compartment of a motor vehicle. The rotary compressor 80 also includes a cylindrical closed container 4 made of steel plate, a motor 6 mounted in the closed container 4, and a compressor 8 comprising rotary compression element 81 which is driven by a shaft 7.

[0049] A predetermined amount of carbon dioxide gas is charged as a refrigerant within the closed container 4, and a predetermined amount of lubricating oil (OL) is received therewithin. A predetermined amount of polyalkylene glycol (PAG) is received as one example of the lubricating oil (OL). However, the lubricating oil (OL) may also be a poly alpha olein (PAO) or a mineral oil.

[0050] The closed container 4 comprises two members, a container main body 4A in which the motor 6 is housed, compressor 8, and a bowl-like end cap 4B closing the open end of the container main body 4A. A terminal (wiring omitted) 11 for supplying electric power to the motor element 6 is provided in the end cap 4B. An oil storage cavity 12 for storing lubricating oil is formed at the other end of the closed container 4.

[0051] The motor 6 comprises a stator 22 mounted along the inner peripheral surface of one end of the container main body 4A of the closed container 4 which surrounds a rotor 24. The rotor 24 is fixed to the shaft 7 which extends in a horizontal direction through the centre thereof.

[0052] The stator 22 has a stator core 26 constructed of laminated ring-like electromagnetic steel plates, and a stator coil 28 wound around the stator core 26. The rotor 24 also has a core 30 made of an electromagnetic steel plate with a permanent magnet inserted into an inner portion thereof, in the same manner as that of the stator 22, to provide a brushless DC motor.

[0053] The rotary compression element 81 comprises a roller 46 positioned within the cylinder 38 and fitted to the eccentric portion 42 provided on the shaft 7 so as to eccentrically rotate a vane (not shown) brought into contact with the roller 46, thus dividing the inner portion of the cylinder 38 into a lower pressure chamber and a high pressure chamber, and a main frame (a left bearing) 51 and an auxiliary frame (a right bearing) 52 which closes an opening surface of the cylinder 38 and also serves as a bearing of the shaft 7.

[0054] A suction passage 53 formed within the cylinder 38 is connected to a suction pipe 54 mounted to the closed container 4. A muffler cover 57 is mounted to the main frame 51, and a sound reduction chamber 58 connected to the inner portion of the cylinder 38 is formed within the muffler cover 57. A muffler cover 59 is mounted to the auxiliary frame 52, and a sound reduction chamber 61 connected to the sound reduction chamber 58 is formed within the muffler cover 59.

[0055] The sound reduction chamber 58 is provided with a discharge port (not shown) formed in the muffler cover 57, and an external pipe 64 is connected to the discharge port. The external pipe 64 goes out of the closed container 4 from the discharge port and is connected to the other end of the closed container 4 adjacent the motor 6 and the terminal 11.

[0056] In the same manner described above, oil pump 66 is provided on an end portion of the auxiliary frame 52, oil suction pipe 67 connected to the oil pump 66 extends downwardly into the oil storage cavity 12, and the lower end of the oil suction pipe 67 is open in the lower portion of the oil storage cavity 12. A discharge pipe 71 is mounted to an upper portion of the closed container 4 remote from the motor 6.

[0057] Partition walls 72 and 73 are provided on the motor 6 side and the oil storage cavity 12 side in the compressor 8 in the same manner as described above. The partition wall 72 is mounted on the muffler cover 57 (however, it may alternatively be mounted on the main frame 51 or the cylinder 38), and connected to the interior wall of the closed container 4 thereby allowing movement of the refrigerant gas and lubricating oil. The partition wall 73 is mounted on the cylinder 38 (however, if may alternatively be mounted on the auxiliary frame 52 or the muffler cover 59), and sections of the inner portion of the closed container 4 into the compression element 8 side and the oil storage cavity 12 side while allowing movement of the refrigerant gas and the lubricating oil. The discharge pipe 71 is positioned on the oil storage cavity 12 side of the partition wall 73.

[0058] In the structure mentioned above, when an electric current is applied to the coil 28 of the motor 6 via the terminal 11 and wiring (not shown), the rotor 24 rotates and the roller 46 fitted to the eccentric portion 42 integrally provided on the shaft 7 eccentrically rotates within the cylinder 38. Accordingly, refrigerant gas is sucked through the suction pipe 54 into the low pressure chamber side of the cylinder 38 via the suction passage 53.

[0059] The low pressure refrigerant gas is compressed by the roller 46 and the vane to a high temperature and pressure and reaches the sound reduction chamber 58 from the high pressure chamber side of the cylinder 38, thereby being discharged through the external pipe 64 from the discharge port. The high temperature and pressure refrigerant gas discharged through the external pipe 64 from the discharge port, is discharged into the closed container 4 after being heat exchanged with the ambient air within the external pipe 64 provided outside the closed container 4 and cooled. As cooled high pressure refrigerant gas travels to the oil storage cavity 12, it cools the motor 6 or cylinder 38 or the like and passes through the gap formed among the closed container 4, the partition wall 72, the cylinder 38 of the compression element 8 and the partition wall 73, and is eventually discharged through the pipe 71.

[0060] Accordingly, a pressure distribution within the closed container 4 is made so that the motor element 6 side of the partition wall 72 has the highest high pressure HH, the compression element 8 portion between the partition walls 72 and 73 has a middle high pressure HM lower than HH and the oil storage cavity 12 in the discharge pipe 71 has the lowest high pressure HL.

[0061] The oil pump 66 is rotated by the shaft 7 and sucks lubricating oil within the oil storage cavity 12 from the lower end opening of the oil suction pipe 67. The lubricating oil is supplied via shaft 7 to the sliding portions within the cylinder 38 and the sliding portions between the respective frames 51 and 52 and the shaft 7.

[0062] Since the pressure distribution within the closed container 4 is such that the motor 6 side of the partition wall 72 has the higher high pressure HH, the space between the partition walls 72 and 73 has the middle high pressure HM, and the oil storage cavity 12 has the lower high pressure HL, the lubricating oil can be held in the oil storage cavity 12 due to the pressure difference between the higher high pressure HH, the middle high pressure HM and the lower high pressure HL. Accordingly, lubricating oil stored in the oil storage cavity 12 is prevented from flowing out to the motor 6 side by the partition walls 73 and 72. Therefore, the oil pump 66 can continuously supply lubricating oil sucked from the interior of the oil storage cavity 12 to the cylinder 38 and the main frame (the left bearing) 51 and the auxiliary frame (the right bearing) 52 serving as the bearing of the shaft 7 while preventing the rotary compressor 80 from being heated.

[0063] A description will now be given with reference to Figure 8, of a two-cylinder rotary compressor in which the oil pump 66 is higher than the motor 6, as the horizontal closed type compressor 1 is inclined. The closed container 4 is inclined at an angle (about 30 degrees) because the oil pump 66 is higher than the motor 6, lubricating oil stored in the oil storage cavity 12 will move under gravity towards the motor 6 side through the gap formed among the partition wall 73, the cylinder 38 and the partition wall 72. However, since the pressure distribution within the closed container 4 is such that the motor 6 side of the partition wall 72 has the higher high pressure HH, the space between the partition walls 72 and 73 has the middle high pressure HM, and the oil storage cavity 12 has the lower high pressure HL, while cooling the motor 6 or the cylinder 38 or the like becoming high temperature by the high pressure refrigerant cooled within the external pipe 64, the lubricating oil stored in the oil storage cavity 12 is prevented from flowing to the motor 6 and the rotary compressor 80 is prevented from being heated. Even if the oil pump 66 is higher than the motor 6, it is still possible to store a small amount of lubricating oil in the motor 6 side of the partition wall 72 having the higher high pressure HH and store most of the lubricating oil in the oil storage cavity 12 (the side of the oil pump 66) corresponding to the right side of the partition wall 73 having the lower high pressure HL.

[0064] Accordingly, even when the temperature of the rotary compressor 80 is increased, using carbon dioxide as the refrigerant, it is still possible to improve the cooling efficiency of the refrigerant discharged from the compressor. If the horizontal closed type compressor mounted on the vehicle is inclined so that the oil pump 66 is higher than the motor 6, it is possible to restrict the drop in the level of the lubricating oil stored in the oil pump 66 side and hence prevent a reduction in lubricating performance. It is also possible to store a predetermined amount of lubricating oil in the oil storage cavity 12 so the oil pump 66 can continuously supply lubricating oil therefrom to the cylinder 38 and the main frame (the left bearing) 51 and the auxiliary frame (the right bearing) 52, serving as the bearing of the shaft 7 while preventing the rotary compressor 80 from being heated.

[0065] A description will now be given with reference to Figure 9 of a two-cylinder rotary compressor 1 in which the motor 6 is higher than the oil pump 66 side as the horizontal closed type compressor is inclined. The closed container 4 is inclined at an angle (about 30 degrees) because the oil pump 66 is lower than the motor 6, lubricating oil stored in the oil storage cavity 12 cannot flow to the motor 6 due to gravitational force. Since the pressure distribution within the closed container 4 is such that the motor 6 of the partition wall 72 has the higher high pressure, the space between the partition walls 72 and 73 has the middle high pressure HM and the oil storage cavity 12 has the lower high pressure HL, lubricating oil stored in the oil storage cavity 12 is prevented from flowing to the motor 6 due to the pressure difference between the partition walls 73 and 72.

[0066] Thus, even when the compressor is inclined so that the motor 6 becomes higher than the oil pump 66, it can continuously supply lubricating oil sucked from the oil storage cavity 12 to the cylinder 38, and the main frame (the left bearing) 51 and the auxiliary frame (the right bearing) 52, which serves as the bearing for the shaft 7 while preventing the rotary compressor 80 from being heated.

[0067] In the embodiment described above, the rotary compressor is employed as one embodiment of closed type compressor. However, the structure is not limited to this, and the present invention can be effectively applied to a closed type scroll compressor comprising a pair of scrolls engaging with each other.

[0068] As described in detail above, in accordance with the present invention, the horizontal closed type compressor for vehicle use is provided with the motor within the closed container so as to direct the rotary shaft in the lateral direction, the compression element driven by the motor element, the lubricating oil received in the closed container, and the oil supplying means for feeding the lubricating oil to the compression element, the oil supplying means being provided in the opposite side to the motor element of the compression element. The compression element compresses the refrigerant gas sucked from the external portion of the closed container so as to discharge to the motor element side within the closed container, and thereafter discharge out of the closed container from the oil supplying means side. The partition walls section the interior portion of the closed container while allowing the refrigerant gas and the lubricating oil to move, are respectively provided in the motor element side and the oil supplying means side of the compression element. Accordingly, since the structure is made such that the pressure in the motor element side becomes higher than that in the oil supplying means side, even in the case that the oil supplying means side of the horizontal closed type compressor becomes high due to the incline of the vehicle, it is possible to prevent the lubricating oil stored in the side of the oil supplying means within the closed container from flowing out to the motor element side as the partition wall acts as a barrier. Accordingly, it is possible to restrict the drop in the level of the lubricating oil stored in the oil supplying means side and hence prevent the lubricating performance from being reduced. Accordingly, since a predetermined amount of lubricating oil can be stored in the oil supplying means side within the closed container, even if the horizontal closed type compressor is inclined so that oil supplying means side is higher, the oil supplying means can continuously supply the lubricating oil, sucked from the inner portion of the oil supplying means within the closed container, to the cylinder and the bearing frame.

[0069] Since the horizontal closed type compressor is provided with the external pipe for discharging the refrigerant gas from the compression element to the motor element side of the closed container, it is possible to cool the high temperature refrigerant gas in the step of passing through the external pipe. Accordingly, even in the case that a refrigerant such as carbon dioxide is used and the temperature of the horizontal closed type compressor is increased, it is possible to significantly improve the cooling efficiency of the refrigerant discharged from the compressor.

[0070] Since the horizontal closed type compressor in accordance with the present invention is structured, such that the compression element is comprised of a plurality of rotary compression elements provided between both of the partition walls, it is possible to set the space between the partition walls so that the pressure on the side of the motor element is high, the side of the oil supplying means is low and the intermediate pressure can be easily generated in a middle thereof. Accordingly, it is possible to easily store the lubricating oil in the side of the oil supplying means due to a pressure difference between the respective partition walls. Therefore, even in the case that the horizontal closed type compressor is inclined, oil supplying means side is higher than the motor element side, it is possible to store predetermined amount of lubricating oil in the oil storage portion, and the oil supplying means can continuously supply the lubricating oil from the inner portion of the oil storage portion to the cylinder and the bearing frame, thus, significantly improving the lubricating performance.

[0071] A description will now be given in detail with reference to Figure 10, of an embodiment of the invention described in the fourth aspect and the fifth aspect.

[0072] A rotary compressor 101 of a cooling system in an electric compressor for vehicle use in accordance with the present invention constitutes a refrigerant circuit of a car air-conditioner for air conditioning a passenger compartment of the motor vehicle (not shown), and is horizontally mounted, within the engine compartment of the motor vehicle. The rotary compressor 101 comprises a cylindrical closed container 104 made of steel plate with a motor 106 mounted therein, and a compressor 108 comprising a first rotary compression element 102 and a second rotary compression element 103 driven by shaft 107 arranged horizontally in line with the motor 106 in the axial direction of the closed container 104.

[0073] Further, a predetermined amount of carbon dioxide is charged as a refrigerant within the closed container 104, and a predetermined amount of lubricating oil (OL) is received therewithin. A predetermined amount of polyalkylene glycol (PAG) is received as one example of the lubricating oil (OL). However, the lubricating oil (OL) may alternatively be a poly alpha olein (PAO) or mineral oil.

[0074] In the illustrated embodiment, the closed container 104 comprises an open ended container main body 104A housing the motor 106 and compressor 108 closed by a bowl-like end cap 104B provided with a terminal (wiring omitted) 111 for supplying electric power to the motor element 106. An oil storage cavity 112 for storing the lubricating oil is provided in the closed container 104 at the end thereof opposite to the motor 106.

[0075] The motor 106 comprises a stator 122 mounted along the inner peripheral surface of one end of the container main body 104A, and a rotor 124 located within, and surrounded by the stator 122. The rotor 124 is fixed to the shaft 107 which extends in a horizontal direction through the centre thereof.

[0076] The stator 122 has a stator core 126 constructed of laminated ring-like electromagnetic steel plates, and a stator coil 128 wound around the stator core 126. The rotor 124 is also formed of a core 130 made of an electromagnetic steel plate with a permanent magnet inserted into an inner portion thereof, in the same manner as that of the stator 122, whereby a brushless DC motor is constituted by both elements.

[0077] An intermediate partition plate 136 is held between the first and second rotary compression elements 102,103. The first rotary compression element 102 and the second rotary compression element 103 are constituted by the intermediate partition plate 136 with cylinders 138 and 140 being arranged on either side thereof. Left and right rollers 146 and 148 are positioned within the cylinders 138 and 140 and fitted to left and right eccentric portions 142 and 144 provided on the shaft 107 with a phase difference of 180 degrees so as to respectively divide the inner portions of the cylinders 138 and 140 into high and low pressure chambers. A main frame (a left bearing) 151 and an auxiliary frame (a right bearing) 152 close the respective opening surfaces of the cylinders 138 and 140 and also serve as a bearing for the shaft 107.

[0078] A suction passage 153 is formed within the cylinder 138 and connected to a suction pipe 154 mounted on the container 104. The suction pipe 154 is connected to a cooler (not shown) for artificial cooling provided within the passenger compartment. A series of branch suction passages 156 connected to the suction passage 153 are formed within the intermediate partition plate 136 and cylinder 140. A muffler cover 157 is mounted to the main frame 151, and a sound reduction chamber 158 connected to the inner portion of the cylinder 138 is formed within the muffler cover 157. A muffler cover 159 is mounted to the auxiliary frame 152, and a sound reduction chamber 161 connected to the inner portion of the cylinder 140 is formed within the muffler cover 159.

[0079] The sound reduction chamber 161 is connected to the interior of the sound reduction chamber 158 by a passage 162 which extends through the cylinders 138 and 140 and the intermediate partition plate 136. The sound reduction chamber 158 is structured so that the external pipe 164 is connected to a discharge port (not shown) formed in the muffler cover 157. The external pipe 164 goes out of the closed container 104 from the discharge port and is connected to the interior of the closed container 104 (on the motor 106 side) via a heat radiating device 175 corresponding to the heat exchanging means.

[0080] The heat radiating device 175 is mounted on a radiator (not shown) of an engine cooling system provided in the vehicle, and is arranged so as to establish a heat exchange relationship with the radiator. That is, the heat radiating device 175 is integrally mounted to a heat radiating fin constituting the radiator of the vehicle, and when water for cooling the engine is circulated within the radiator, the high temperature refrigerant gas passing through the heat radiating device 175 exchanges heat with the cooling water. The cooling water within the radiator is maintained at a temperature of between about 80°C to 100°C at which the water is not boiled, and the carbon dioxide refrigerant gas discharged from the compression element 108 of the electric compressor is at a temperature of over 200°C. Accordingly, a temperature difference is generated between the cooling water circulating within the radiator and the refrigerant gas passing through the interior of the heat radiating device 175, resulting in heat exchange. It is conventional and well-known that the cooling water within the radiator is maintained at the temperature from about 80°C to 100°C at which the water is not boiled.

[0081] An oil pump 66 providing the oil supplying means is mounted at the end of the shaft 107 opposite to the motor 106. An oil suction pipe 167 is provided in the oil pump 166 and extends downwardly into the oil storage cavity 112. A discharge pipe 171 is mounted to an upper portion of the end of closed container 104 opposite the motor 106 in the side of the oil storage cavity 112 of the cylinder 140.

[0082] Partition walls 172 and 173 are provided in the motor 106 side and oil storage cavity 112 side of the compression element 108. Partition wall 172 is mounted to the muffler cover 157 (however, it may alternatively be mounted to the main frame 151 or the cylinder 138), and divides the interior of the closed container 104 into a motor 106 side and a compression element 108 side while allowing movement of the refrigerant gas and the lubricating oil. Partition wall 173 is mounted to the cylinder 140 (however, it may alternatively be mounted to the auxiliary frame 152 or the muffler cover 159), and divides the interior of the closed container 104 into a compression element 108 side and an oil storage cavity 112 side while allowing movement of the refrigerant gas and the lubricating oil. Discharge pipe 171 is positioned on the oil storage cavity 112 side of the partition wall 173.

[0083] In the structure described above, when an electric current is applied to the coil 128 of the motor 106 via the terminal 111 and wiring (not shown), the rotor 124 rotates and the left and right rollers 146 and 148 fitted to the left and right eccentric portions 142 and 144 integrally on the shaft 107 eccentrically rotate within the left and right cylinders 138 and 140.

[0084] Accordingly, refrigerant gas is sucked through the suction pipe 154 into the low pressure chamber side of the cylinder 138 via the suction passage 153, and into the lower pressure chamber side of the cylinder 140 via the branch suction passage 156.

[0085] The low pressure refrigerant gas is compressed by the roller 146, the roller 148 and the vane, to a high temperature and pressure and reaches the sound reduction chamber 158 from the high pressure chamber side of the cylinder 138, where it is discharged via the external pipe 164 from the discharge port. The refrigerant gas reaches the sound reduction chamber 158 from the high pressure chamber side of the cylinder 140 via the sound reduction chamber 161 and the connecting passage 162 and is discharged via external pipe 164 from the discharge port.

[0086] The high temperature and high pressure refrigerant gas discharged via the external pipe 164 from the discharge port, flows into the heat radiating device 175 through the external pipe 164 where it is heat exchanged with the cooling water circulating within the radiator so as to radiate heat and be cooled, and thereafter is discharged to closed container 104 (on the side of the motor 106). The high pressure refrigerant gas cooled and discharged into the closed container 104 reaches the oil storage cavity 112 side within the closed container 104 while cooling the motor 106 or respective cylinders 138 and 140 and heats up as it passes through the gap formed between the respective cylinders 138 and 140 of the compression element 108 and the partition wall 173 so as to be discharged to the exterior from the discharge pipe 171, resulting in the passenger compartment being cooled.

[0087] A pressure distribution within the closed container 104 is established such that the motor 106 side of the partition wall 172 has a highest high pressure HH, the intermediate partition plate 136 portion of the compression element 108 between the partition walls 172 and 173 has a middle high pressure HM, lower than HH, and the oil storage cavity 112 side of the partition wall 173 in the discharge pipe 171 has a lowest high pressure HL.

[0088] The oil pump 166 is rotated by the shaft 107 and lubricating oil within the oil storage cavity 112 is supplied via pipe 167 to the sliding portions within the respective cylinders 138 and 140 and the sliding portions between the respective frames 151 and 152 and the shaft 107 through the shaft 107.

[0089] Since the pressure distribution within the closed container 104 is made so that the motor 106 side of the partition wall 72 has the higher high pressure HH, the partition walls 172 and 173 have the middle high pressure HM, and the oil storage cavity 112 side of the partition wall 173 has the lower high pressure HL, the lubricating oil can be held in the oil storage cavity 112 (on the oil pump 106 side). Accordingly, the lubricating oil stored in the oil storage cavity 112 can be prevented from flowing out to the motor 106 side by the partition walls 173 and 172. Therefore, the oil pump 166 can continuously supply lubricating oil sucked from the interior of the oil storage cavity 12 to the cylinders 38 and 40 and the main frame (the left bearing) 51 and the auxiliary frame (the right bearing) 52 which serves as the bearing of the shaft 7 while preventing the rotary compressor 101 from being heated.

[0090] As mentioned above, as the external pipe 164 is connected to the discharge port of the compression element 108, and the heat radiating device 175 is arranged in the external pipe 164 so as to establish a heat exchange relationship with the radiator for cooling the engine of the vehicle, it is possible to heat exchange the high temperature refrigerant gas compressed by the compression element 108, with the cooling water circulating within the radiator. Accordingly, a conventional specific heat radiating device is not required and it is therefore possible to effectively use the engine compartment of limited space.

[0091] When carbon dioxide is used as the natural refrigerant of the electric compressor, the refrigerant gas discharged from the compression element 108 heats up in accordance with the property of the natural refrigerant. Accordingly, the temperatures of the motor 106 and the lubricating oil are increased. However, the high temperature refrigerant gas discharged from the compression element 108 can be heat radiated when passing through the inner portion of the heat radiating device 175. Since it is possible to radiate the heat of the high temperature refrigerant gas discharged from the compression element 108, even if the electric compressor is placed in the engine compartment of the vehicle which becomes hot, it is possible to prevent the temperatures of the motor element 106 and the lubricating oil from increasing.

[0092] The rotary compressor is employed as one embodiment of the closed type compressor. However, the structure is not limited to this, and the present invention can be effectively applied to a closed type scroll compressor comprising a pair of scrolls engaging with each other.

[0093] As described in detail above, and in accordance with the invention, the structure is made such that there is provided an electric compressor having a motor within the closed container which drives the compression element to compress the refrigerant gas sucked from the exterior of the closed container by the compression element. This gas is discharged to the exterior of the closed container, and the heat exchanging relation with the engine cooling system of the vehicle. The refrigerant gas discharged from the compression element flows to the heat exchanging means, and is returned to the motor side within the closed container and thereafter is discharged to the exterior of the closed container. The high temperature refrigerant gas discharged from the compression element can be radiated by passing it through heat exchanging means arranged so as to establish a heat exchanging relation with the engine cooling system of the vehicle. Accordingly, since it is not necessary to provide a special radiator, it is possible to efficiently use, for example, the engine compartment of limited space.

[0094] When using carbon dioxide as a natural refrigerant in the electric compressor, the refrigerant gas discharged from the compression element becomes hot on the basis of the property of the natural refrigerant, and the temperatures of the motor element and the lubricating oil are increased. However, since the high temperature refrigerant gas discharged from the compression element can be radiated by passing it through the heat exchanging means, it is possible to prevent the temperatures of the motor element and the lubricating oil from increasing. Accordingly, if the electric compressor is located in the engine compartment of a vehicle or the like which can become hot, it is possible to prevent the temperatures of the motor and the lubricating oil from increasing.

[0095] Since the heat exchanging means is arranged so as to establish the heat exchanging relationship with the radiator of the vehicle, it is possible to cool the high temperature refrigerant gas discharged from the electric compressor, using, for example, the radiator for cooling the engine of the vehicle. Accordingly, it is possible to prevent the compressor becoming so hot that it burns out.

Claims

1. A cooling system for an electric compressor for vehicle use comprising an electric compressor having a motor housed within a closed container and a compression element driven by said motor which compresses a refrigerant gas drawn from the exterior of said closed container and thereafter discharging it to the exterior of said closed container, and heat exchanging means arranged to establish a heat exchanging relationship with an engine cooling system of the vehicle, wherein the refrigerant gas discharged from said compression element flows to said heat exchanging means and returns to the said motor side within said closed container and thereafter is discharged to the exterior of said closed container.

2. A cooling system of an electric compressor as claimed in claim 1 wherein said heat exchanging means is arranged to establish a heat exchanging relationship with a radiator of said vehicle.

Drawing