JP2008115731A - Cooling system for electrically-driven supercharger - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To effectively cool an electric motor arranged between a turbine and compressor in a cooling system for an electrically-driven supercharger. <P>SOLUTION: The electrically-driven supercharger 10 comprises the compressor 12 for pressurizing intake air of an internal combustion engine, the turbine 14 for converting exhaust energy into rotary force of the compressor 12, and the electric motor 16 which is arranged between the compressor 12 and turbine 14 and assists rotation of the compressor 12. A gap cooling passage 106 is arranged to inject oil into a gap 96 between a rotor 80 and stator 94 of the electric motor 16. The gap cooling passage 106 is formed at the compressor 12 side against the electric motor 16. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an electric drive supercharger cooling system, and more particularly, to an electric drive supercharger cooling system suitable as a system for cooling an electric drive supercharger incorporated in an in-vehicle internal combustion engine.

  Conventionally, as disclosed in, for example, Japanese Patent Application Laid-Open No. 5-256155, an electric drive supercharger having an assist function by an electric motor is known. The conventional electric drive supercharger includes an electric motor between a compressor provided on the intake side and a turbine provided on the exhaust side. The rotation shafts of the compressor and the turbine are integrated, and when the turbine is rotated by exhaust energy, the compressor pressurizes intake air and supercharges the internal combustion engine.

  In a high load region where the exhaust energy is sufficiently large, the change in the throttle opening is quickly reflected in the change in the exhaust energy. In this case, the rotational speed of the turbine and the compressor (turbo rotational speed) reacts quickly with respect to the throttle opening, and as a result, the internal combustion engine exhibits excellent responsiveness. On the other hand, in a low load region where the exhaust energy is small, a so-called turbo lag is generated with a certain delay until the change in the throttle opening is reflected in the turbine speed.

  According to the electric drive supercharger, turbo rotation can be assisted by the electric motor in a low load region in which turbo lag is likely to occur. For this reason, according to the electrically driven supercharger, the responsiveness of the internal combustion engine can be improved particularly in a low load region.

  The conventional electric drive supercharger includes a mechanism for cooling the electric motor in order to prevent the electric motor from overheating. Specifically, the conventional electrically driven supercharger includes a jet injection hole facing the gap between the stator and rotor of the electric motor, and a coolant path communicating with the jet injection hole between the electric motor and the turbine. In preparation. A mixture of compressed air and oil is supplied to the coolant path, and the electric motor is cooled by the mixture.

  If the gap between the stator and the rotor is overheated, there will be inconveniences such as carbon adhering between them and the efficiency of the supercharger deteriorates. If the gap between the stator and the rotor can be appropriately cooled by the above-described conventional configuration, overheating of the gap can be prevented, and the operating characteristics of the electrically driven supercharger can be prevented from deteriorating. .

JP-A-5-256155 JP 2004-3420 A JP 2003-239756 A JP 2004-108213 A

  By the way, in the conventional electric drive supercharger, a path for introducing the coolant into the gap between the stator and the rotor is provided on the turbine side of the electric motor. Since the turbine is driven by exhaust gas, it tends to be hot. For this reason, when the coolant path is provided in the vicinity of the turbine, the coolant is heated in the process of passing through the coolant path. In order to efficiently cool the electric motor, it is desirable that the coolant is at a low temperature. In this regard, the configuration of the conventional electric drive supercharger is not necessarily ideal for cooling the electric motor.

  Further, in the conventional electric drive supercharger, no consideration is given to the timing of injecting the coolant into the gap between the stator and the rotor. The coolant injected into the gap between the stator and the rotor becomes a resistor that prevents the rotor from rotating. For this reason, when the coolant is injected, the efficiency of the supercharger may decrease, and the output of the internal combustion engine may decrease. In this regard, the conventional electric drive supercharger has a possibility of deteriorating the drivability of the vehicle when the electric motor is cooled.

  The present invention has been made to solve the above-described problems, and provides an electrically driven supercharger cooling system capable of efficiently cooling an electric motor disposed between a turbine and a compressor. With the goal.

  The present invention has been made to solve the above-described problems, and provides an electric drive supercharger cooling system capable of efficiently cooling an electric motor without deteriorating the drivability of the vehicle. With the goal.

In order to achieve the above object, a first invention is an electrically driven supercharger cooling system,
A compressor for pressurizing the intake air of the internal combustion engine;
A turbine that converts exhaust energy into rotational force of the compressor;
An electric motor disposed between the compressor and the turbine and assisting the rotation of the compressor;
A gap cooling path for injecting coolant into the gap between the rotor and stator of the electric motor,
The gap cooling path extends on the compressor side with respect to the electric motor.

The second invention is the first invention, wherein
A flow rate control means for controlling the flow rate of the coolant injected into the gap from the gap cooling path;
Fuel supply state detection means for detecting the fuel supply state to the internal combustion engine;
An injection prohibiting means for prohibiting the injection of the coolant from the cooling path into the gap when the fuel is constantly supplied to the internal combustion engine and when the amount of fuel supply to the internal combustion engine is increasing;
It is characterized by providing.

  Further, in the third invention according to the second invention, when the fuel supply amount to the internal combustion engine is reduced and when the fuel supply to the internal combustion engine is cut off, the cooling from the cooling path to the gap is performed. An injection command means for commanding the liquid injection is provided.

In a fourth aspect based on the third aspect, the fuel supply state detection means comprises a decrease rate detection means for detecting a decrease rate of the fuel supply amount,
The injection command means includes
An injection amount calculating means for calculating an injection amount of the coolant into the gap based on a decrease rate of the fuel supply amount;
And a flow rate control means for controlling the flow rate control means so that the calculated injection amount is injected.

The fifth invention is the first to fourth inventions,
Temperature detecting means for detecting the temperature of the electric motor;
Forced cooling command means for commanding injection of coolant from the gap cooling path to the gap when the temperature of the electric motor has reached the cooling determination temperature;
It is characterized by providing.

The sixth invention is the first to fifth invention, wherein
Temperature detecting means for detecting the temperature of the electric motor;
Energization cut command means for cutting energization to the motor when the temperature of the motor has reached an allowable upper limit temperature higher than the cooling determination temperature;
It is characterized by providing.

The seventh invention is the first to sixth inventions,
An electric coolant pump provided to supply coolant to the gap cooling path;
Temperature detecting means for detecting the temperature of the electric motor;
A post-stop cooling command means for commanding injection of coolant from the gap cooling path to the gap when the temperature of the electric motor has reached a cooling determination temperature after the internal combustion engine is stopped;
It is characterized by providing.

  The eighth invention is the first to seventh inventions, wherein the lubricating oil supplied to the internal combustion engine and the cooling liquid supplied to the gap cooling path are not mixed with each other. The system for supplying the coolant and the system for supplying the cooling liquid are provided as independent systems.

The ninth invention relates to the first to eighth inventions,
A bearing for rotatably holding the rotor;
A bearing communication path for supplying lubricating oil to the bearing;
A lubricating oil guide mechanism for guiding the lubricating oil supplied to the bearing to the periphery of a coil provided in the stator;
It is characterized by providing.

  According to a tenth aspect of the present invention, in the first to ninth aspects, the gap cooling path opens in a direction parallel to the gap to inject the coolant and faces the end of the gap. An injection hole is provided.

The eleventh aspect of the invention is an electrically driven supercharger cooling system,
A compressor for pressurizing the intake air of the internal combustion engine;
A turbine that converts exhaust energy into rotational force of the compressor;
An electric motor disposed between the compressor and the turbine and assisting the rotation of the compressor;
A gap cooling path for injecting coolant into the gap between the rotor and stator of the electric motor;
A flow rate control means for controlling the flow rate of the coolant injected into the gap from the gap cooling path;
Fuel supply state detection means for detecting the fuel supply state to the internal combustion engine;
An injection prohibiting means for prohibiting the injection of the coolant from the cooling path into the gap when the fuel is constantly supplied to the internal combustion engine and when the amount of fuel supply to the internal combustion engine is increasing;
It is characterized by providing.

  In a twelfth aspect according to the eleventh aspect, when the fuel supply amount to the internal combustion engine is reduced and when the fuel supply to the internal combustion engine is cut off, the cooling from the cooling path to the gap is performed. An injection command means for commanding the liquid injection is provided.

  According to the first invention, the gap cooling path for injecting the coolant into the gap between the rotor and the stator of the electric motor extends on the compressor side with respect to the electric motor. Since the compressor is provided on the intake side, it is sufficiently cooler than the turbine. For this reason, according to this invention, a low-temperature cooling fluid can be injected toward the space | interval of a rotor and a stator, and an electric motor can be cooled efficiently.

  According to the second or eleventh invention, when the fuel is constantly supplied to the internal combustion engine and when the amount of fuel supply to the internal combustion engine is increasing, the coolant for the gap between the rotor and the stator Is prohibited. When the fuel is constantly supplied to the internal combustion engine and when the amount of fuel supply to the internal combustion engine is increasing, it can be determined that the driver does not want to reduce the output of the internal combustion engine. When the coolant is injected under such a situation, the efficiency of the supercharger is lowered, and the output can be reduced unintended by the driver. According to the present invention, it is possible to reliably prevent the deterioration of drivability due to such a decrease in output.

  According to the third or twelfth invention, the coolant is injected into the gap between the rotor and the stator when the fuel supply amount to the internal combustion engine is reduced and when the fuel supply to the internal combustion engine is cut. can do. When the fuel supply amount to the internal combustion engine is decreasing and when the fuel supply to the internal combustion engine is cut off, it can be determined that the driver desires a decrease in the output of the internal combustion engine. According to the present invention, by injecting the coolant in such a situation, it is possible to reduce the efficiency of the supercharger and emphasize the feeling of deceleration.

  According to the fourth aspect of the present invention, the coolant injection amount can be calculated based on the fuel supply amount decrease rate. The decreasing rate of the fuel supply amount has a correlation with the deceleration feeling intended by the driver. On the other hand, the injection amount of the coolant has a correlation with the degree of reduction in efficiency of the supercharger. For this reason, according to the present invention, the efficiency of the electrically driven supercharger can be lowered so as to correspond to the feeling of deceleration intended by the driver.

  According to the fifth aspect, when the temperature of the electric motor reaches the cooling determination temperature, the coolant can be injected unconditionally. For this reason, according to this invention, it can prevent that the temperature of an electric motor rises exceeding cooling determination temperature, and can protect an electric motor appropriately.

  According to the sixth aspect, when the temperature of the electric motor reaches the allowable upper limit temperature, the energization to the electric motor can be forcibly cut. When energization to the motor is cut off, further temperature rise of the motor can be suppressed. For this reason, according to this invention, the overheating of an electric motor can be prevented appropriately.

  According to the seventh aspect, even after the internal combustion engine is stopped, the coolant can be supplied to the gap between the rotor and the stator by the electric coolant pump. In particular, according to the present invention, when the temperature of the electric motor reaches the cooling determination temperature after the internal combustion engine is stopped, the gap between the rotor and the stator can be cooled with the cooling liquid until the temperature decreases. . For this reason, according to the present invention, it is possible to prevent the periphery of the electric motor from being maintained at a high temperature for a long period after the internal combustion engine is stopped.

  According to the eighth invention, the system for supplying the lubricating oil to the internal combustion engine and the system for supplying the cooling liquid to the gap between the stator and the rotor are independent. For this reason, according to this invention, lubricating oil and a cooling fluid can be used properly. The characteristics required for the lubrication of the internal combustion engine may differ from the characteristics required for cooling the supercharger. According to the present invention, the performance of the internal combustion engine can be maximized by giving optimum characteristics to both.

  According to the ninth aspect, the periphery of the stator coil can be cooled by the lubricating oil for obtaining lubrication between the rotor and the bearing. Lubricating oil supplied to the periphery of the coil does not adversely affect the efficiency of the supercharger. For this reason, according to this invention, the coil periphery of an electric motor can be cooled efficiently, without reducing the efficiency of an electric drive supercharger.

  According to the tenth aspect, the coolant can be blown into the gap between the stator and the rotor from the injection hole communicating with the gap cooling path. For this reason, according to this invention, the inside of said gap | interval can be cooled efficiently.

Embodiment 1 FIG.
[Configuration of Embodiment 1]
FIG. 1 is a diagram for explaining the overall configuration of the first embodiment of the present invention. As shown in FIG. 1, the system of the present embodiment includes an electric drive supercharger 10. The electric drive supercharger 10 includes a compressor 12, a turbine 14, and an electric motor 16.

  The compressor 12 is incorporated in the intake passage 22 of the internal combustion engine 20. That is, the compressor 12 communicates with the air cleaner 24 on the upstream side. In addition, an intake manifold 32 of the internal combustion engine 20 communicates with the downstream side of the compressor 12 via a supercharging pressure sensor 26, an intercooler 28, and a throttle valve 30.

  The turbine 14 is incorporated in the exhaust passage 34 of the internal combustion engine 20. That is, the turbine 14 communicates with the exhaust manifold 36 of the internal combustion engine 20 on the upstream side thereof, and communicates with the exhaust gas purification catalyst 38 on the downstream side thereof.

  The exhaust manifold 36 and the intake manifold 32 communicate with each other via an EGR passage 40 for returning exhaust gas to the intake side. An EGR cooler 44 and an EGR valve 46 are incorporated in the EGR passage 40.

  The electric motor 16 is disposed between the compressor 12 and the turbine 14. The rotating shaft of the compressor 12, the rotating shaft of the turbine 14, and the rotating shaft of the electric motor 16 are integrated with each other. For this reason, the rotation of the turbine 14 is transmitted to the compressor 10, and the rotation of the electric motor 16 is also transmitted to the compressor 10.

  The turbine 14 is rotated by the energy of the exhaust gas discharged from the internal combustion engine 20. The compressor 12 rotates as the turbine 14 rotates, compresses the air sucked from the air cleaner 24 side, and supercharges the internal combustion engine 20. The electric motor 16 can assist the rotation of the compressor 12. For this reason, according to the electrically driven supercharger 10, even when the exhaust energy is small and the turbine 14 cannot generate sufficient rotation, a sufficient supercharging pressure can be generated by using the electric assist. .

  In the present embodiment, the oil pump of the internal combustion engine 20 is connected to the electric motor 16 via the oil control valve 48. That is, the electric motor 16 is supplied with oil discharged from the oil pump 50 of the internal combustion engine 20 via the oil control valve 48. The system of this embodiment is characterized in that oil is used inside the electric motor 16. This feature point will be described in detail later with reference to FIGS.

  As shown in FIG. 1, the system of this embodiment includes an ECU (Electric Control Unit) 60. The ECU 60 is a unit that controls the operation of the internal combustion engine 20. The ECU 60 includes a rotational speed sensor 62 that detects the engine rotational speed Ne, an exhaust temperature sensor 64 that detects the exhaust gas temperature, an accelerator opening sensor 66 that detects the accelerator opening, and a motor that detects the stator temperature of the electric motor 16. A stator temperature sensor 68 and the like are connected. The ECU 50 controls the state of the oil control valve 48 and the state of the electric motor 16 based on these sensor outputs.

[Internal structure of electric drive supercharger]
FIG. 2 is a diagram for explaining the internal structure of the electric drive supercharger 10. As shown in FIG. 2, the electric drive supercharger 10 includes a housing 70. A rotation shaft 72 is disposed at the center of the housing 70. A compressor impeller 74 is provided at the end of the rotating shaft 72 on the compressor 12 side. A turbine impeller 76 is provided at the end of the rotating shaft 72 on the turbine 14 side.

  A magnet 78 and a rotor 80 are attached to the center of the rotating shaft 72. Both ends of the rotor 80 are rotatably held by bearings 82 and 84. A thrust collar 86 is attached to the rotating shaft 72 so as to contact the end of the rotor 80 on the compressor 12 side. A seal ring collar 88 and a seal ring 90 are mounted further on the compressor 12 side of the thrust collar 86. On the other hand, a seal ring 92 is also attached to the bearing 72 between the bearing 84 on the turbine 12 side and the turbine impeller 76. A space through which oil supplied from the oil pump 50 flows is formed between the two seal rings 90 and 92.

  A stator 94 formed so as to surround the rotor 80 is fixed to the housing 70. A gap 96 is formed between the rotor 80 and the stator 94. The stator 94 has a plurality of comb-like members extending radially from the center of the rotor 80, and a coil 96 is formed on each of the comb-like members.

  A cooling water passage 100 is formed in the housing 70 at a position surrounding the stator 94. The electrically driven supercharger 10 can be cooled by circulating cooling water through the cooling water passage 100.

  The housing 70 is provided with a bearing communication path 102 that communicates with a bearing 82 on the compressor 12 side, and a bearing communication path 104 that communicates with a bearing 84 on the turbine 14 side. Specifically, the former bearing communication path 102 is provided on the compressor 12 side when viewed from the stator 94 of the electric motor 16, and communicates with the outer periphery of the thrust collar 86 in addition to the passage communicating with the outer periphery of the bearing 82. Has a branch. On the other hand, the latter bearing communication path 104 is provided on the turbine 14 side when viewed from the stator 94 of the electric motor 16.

  An oil pump 50 of the internal combustion engine 20 communicates with the bearing communication paths 102 and 104, respectively. For this reason, the bearing communication paths 102 and 104 circulate the oil discharged from the oil pump 50 to the outer peripheral surfaces of the bearing portions 82 and 84 and the thrust collar 86 during the operation of the internal combustion engine 20.

  The bearings 82 and 84 are annular members, and are provided with a plurality of through passages penetrating from the outer peripheral surface to the inner peripheral surface at equal intervals over the entire circumference. For this reason, the oil guided to the outer peripheral surfaces of the bearings 82 and 84 also enters the bearings 82 and 84 through the through passages. The oil guided to the inside and outside of the bearing portions 82 and 84 then flows out toward the center of the electric motor 16 through a gap provided between the rotating shaft 72 and the housing.

  Since the rotor 78 is rotating during the operation of the internal combustion engine 20, the oil that flows out from the periphery of the bearings 82 and 84 toward the center of the electric motor 16 is scattered by the centrifugal force of the rotor 78. The scattered oil adheres to the periphery of the coil 96 of the stator 94 and cools the coil 96. As a result, in the system of the present embodiment, the periphery of the coil 96 can be efficiently cooled during operation of the internal combustion engine 20.

  In the housing 70, a gap cooling path 106 is further provided on the compressor 12 side as viewed from the stator 98. The gap cooling path 106 is a path for jetting oil into a gap 96 formed between the rotor 80 and the stator 94, and includes an injection hole 108 at a position facing the gap 96. . In FIG. 2, the gap 96 extends in the horizontal direction. The injection hole 108 is provided so that oil can be injected in a direction parallel to the direction of the gap 96.

  The gap cooling path 106 communicates with the oil pump 50 via the oil control valve 48. For this reason, according to the system of this embodiment, a part of the oil discharged by the oil pump 50 can be jet-injected into the gap 96 between the rotor 80 and the stator 94. Furthermore, by controlling the oil control valve 48, the amount of oil injected from the injection hole 108 into the gap 96 can be controlled.

  As described with reference to FIG. 1, the compressor 12 is a component located on the intake side of the internal combustion engine 20. On the other hand, the turbine 14 is a component located on the exhaust side of the internal combustion engine 20. For this reason, the electrically driven supercharger 10 is likely to be at a lower temperature on the compressor 12 side than on the turbine 14 side.

  As described above, the gap cooling passage 106 is provided on the compressor 12 side when viewed from the stator 94 (the electric motor 16). For this reason, according to the gap cooling passage 106, the oil that has passed through the oil control valve 48 can be conveyed to the injection hole 108 without being heated greatly during the conveyance process. The injection hole 108 is provided so as to face the gap 96. For this reason, the oil injected from the injection hole 108 can enter deeply into the gap 96. Therefore, according to the system of this embodiment, the inside of the gap 96 can be efficiently cooled deeply.

  The housing 70 is further provided with an oil drain portion 109 at a position below the electrically driven supercharger 10. The oil supplied to the inside of the housing 70 via the bearing communication paths 102 and 104 and the gap cooling path 106 is finally collected in the oil tank through the oil drain portion 109.

[Control in Embodiment 1]
By the way, the oil that is injected from the injection hole 108 and enters the inside of the gap 96 becomes a resistor that increases the rotational resistance of the rotor 80. For this reason, when oil is injected toward the gap 96, the efficiency of the electrically driven supercharger 10 is reduced, and the output of the internal combustion engine 20 is reduced. Therefore, if the oil injection is performed in a situation where the driver of the vehicle does not intend to decrease the output, an output decrease unintended by the driver occurs, and the drivability of the vehicle deteriorates.

  On the other hand, when the driver executes the above oil injection under a situation where the output is intended to be reduced, the efficiency of the electric drive supercharger 10 is reduced, as compared with the case where the efficiency is maintained. Can produce a great feeling of deceleration. That is, in this case, a feeling of deceleration that matches the driver's intention can be generated. Therefore, in the present embodiment, in principle, oil injection into the gap 96 is performed under a situation where the driver desires a reduction in output, and under a situation where the driver does not desire a reduction in output, the oil injection into the gap 96 is performed. Oil injection was prohibited.

FIG. 3 is a flowchart of a routine executed by the ECU 60 in the present embodiment in order to realize the above-described principle operation while reliably preventing the motor 16 from being overheated. In the routine shown in FIG. 3, first, the temperature of the stator 94 of the motor 16, whether or not reached in the cooling determination temperature T _B is determined (Step 110). As a result, if the temperature of the stator 94 is determined to have reached the cooling determination temperature T _B, further, the temperature thereof, whether or not reached the allowable upper limit temperature T _A is determined (step 112) .

Figure 4 is a cooling determination temperature T _B, showing the relationship between the allowable upper limit temperature T _A FIG. Cooling determination temperature T _B is not a temperature determines the overheating taking the motor 16, the temperature rise of more is a temperature defined as a value that is desirable to block. Further, the allowable upper limit temperature T _A, the upper limit of the temperature allowed in the motor 16, the temperature rise of more is the temperature defined as shall prevent values.

If the temperature of the stator 94 is greater than the cooling determination temperature T _B, it is necessary to suppress the temperature rise of the motor 16. The temperature rise of the electric motor 16 can be suppressed by jetting oil toward the gap 96, and when the electric motor 16 is energized, it can also be suppressed by cutting the energization. However, the electric motor 16 is energized in a situation where it is necessary to assist the rotation of the compressor 12. For this reason, the energization cut of the electric motor 16 tends to affect the drivability of the vehicle.

In step 112, if the temperature of the stator 94 is not reached the allowable upper limit temperature T _A, the temperature is located between the cooling determination temperature T _B and the allowable upper limit temperature T _A I can judge. Under such circumstances, the temperature of the electric motor 16 still has room, so it is desirable to prioritize ensuring drivability over quickly reducing the temperature. Therefore, in the routine shown in FIG. 3, in this case, the motor 16 is cooled by jetting oil toward the gap 96 without cutting the energization of the motor 16 (step 114).

On the other hand, when it is determined in step 112 that the temperature of the stator 94 has reached the allowable upper limit temperature T _A , it is necessary to immediately stop further temperature increase of the electric motor 16 and quickly reduce the temperature. It can be judged that there is. In this case, in the routine shown in FIG. 3, the energization cut of the electric motor 16 (step 116) and the oil injection into the gap 96 (step 114) are executed together to satisfy the request. By performing the above processing, according to the system of the present embodiment, it is possible to reliably prevent the electric motor 16 from falling into an overheated state while minimizing deterioration in drivability of the vehicle.

During the routine shown in FIG. 3, in step 110, if the temperature of the stator 94 is not reached the cooling determination temperature T _B, it can be determined that there is no need to forcibly cool the electric motor 16 at the present time . In this case, it is next determined whether the fuel supply amount to the internal combustion engine 20 has decreased or the fuel supply to the internal combustion engine 20 has been cut (step 118).

  In addition to the routine shown in FIG. 3, the ECU 60 executes a routine for calculating the fuel injection amount for the internal combustion engine 20. Therefore, the ECU 60 can detect a change in the fuel injection amount and a fuel cut state based on the calculation result of the routine. In step 118, it is determined whether the fuel injection amount has decreased or whether or not there has been a cut based on the detection result.

  If the condition of step 118 is not satisfied, it can be determined that a substantially constant amount of fuel is constantly being injected into the internal combustion engine 20 or that the fuel supply amount to the internal combustion engine 20 is increasing. These situations occur when the driver does not want to reduce the output of the internal combustion engine 20. For this reason, in such a situation, it is desirable not to perform oil injection into the gap 96 that causes a reduction in efficiency of the electrically driven supercharger 10. Therefore, in the routine shown in FIG. 3, if it is determined in step 118 that the condition is not satisfied, the current processing cycle is terminated without performing oil injection into the gap 96.

  On the other hand, if it is determined in step 118 that the fuel injection amount is decreasing or the fuel injection is cut off, it can be determined that the driver desires a reduction in the output of the internal combustion engine 20. In this case, first, a decrease rate of the fuel injection amount is detected in order to estimate how much the driver wants to reduce the output (step 120).

  Next, the flow rate of oil to be supplied by jet injection toward the gap 96 is calculated based on the decreasing rate of the fuel injection amount (step 122). The ECU 60 stores a map that defines the oil injection amount into the gap 96 in relation to the rate of decrease in the fuel injection amount. Here, the oil flow rate is calculated with reference to this map.

  When step 114 is executed after step 122, the oil control valve 48 is controlled to inject the oil flow rate calculated at step 122. The map used in step 122 is determined so that the amount of oil injected toward the gap 96 is large enough that it can be determined that the rate of decrease in the fuel injection amount is fast and the driver desires a large reduction in output. It has been. As the amount of oil injected into the gap 96 increases, the efficiency of the electrically driven supercharger 10 decreases, and as a result, the output of the internal combustion engine 20 decreases. For this reason, according to said process, the deceleration according to a driver | operator's intent can be generated with the oil injected to the clearance gap 96. FIG.

As described above, according to the process shown in FIG. 3, when the temperature of the motor 16 exceeds the cooling determination temperature T _B is is possible to protect the motor 16 by forcedly cooling gaps 96 it can. Further, when the driver does not intend to decrease the output of the internal combustion engine 20, in principle, oil injection into the gap 96 can be prohibited to prevent an unintended output decrease. Furthermore, when the driver intends to reduce the output, the desired deceleration feeling can be generated while the motor 16 is cooled by injecting oil into the gap 96. For this reason, according to the system of this embodiment, it is possible to cool the electric motor 16 efficiently while reliably protecting the electric motor 16 and ensuring the drivability of the vehicle.

  In the first embodiment described above, the configuration in which the gap cooling path 106 is disposed on the compressor 12 side of the electric motor 16 and the processing shown in FIG. 3 are used in combination, but these are necessarily used in combination. There is no need. Further, in the routine shown in FIG. 3, a process for protecting the electric motor 16 (steps 110 to 114) and a process for ensuring drivability (the routine is terminated without oil injection when the condition in step 118 is not satisfied). And a process for generating a desired deceleration feeling (execution of oil injection when the condition of step 118 is satisfied) are executed in combination. However, these processes are not necessarily executed in combination and are independent of each other. Thus, the electric drive supercharger 10 may be used for control. These points are the same in other embodiments described below.

  In the first embodiment described above, oil corresponds to the “cooling liquid” in the second or eleventh invention, and the oil control valve 48 corresponds to the “flow control means” in the second or eleventh invention. is doing. Further, when the ECU 60 detects the state of fuel supply to the internal combustion engine 20, the “fuel supply state detection means” in the second or eleventh aspect of the invention performs a routine without executing step 114 when the condition of step 118 is not satisfied. The “injection prohibiting means” in the second or eleventh aspect of the present invention is realized by terminating the process.

  In the first embodiment described above, the “injection command means” according to the third or twelfth aspect of the present invention is realized by the ECU 60 executing the process of step 114 when the condition of step 118 is satisfied.

  Further, in the first embodiment described above, the ECU 60 executes the process of step 120, so that the “decrease speed detecting means” in the fourth invention executes the process of step 122. The “injection amount calculation means” in the invention implements the processing of step 114 in order to inject the oil flow rate calculated in step 122, thereby realizing the “flow rate control means” in the fourth invention. .

  In the first embodiment described above, the motor stator temperature sensor 68 corresponds to the “temperature detection means” in the fifth or sixth invention, and the ECU 60 performs step 114 when the condition of step 110 is satisfied. When executed, the “forced cooling command means” in the fifth invention realizes the “energization cut command means” in the sixth invention by executing the processing of step 116 when the condition of step 112 is satisfied. ing.

  In the first embodiment described above, the oil supplied to the bearings 82 and 84 flows out toward the center of the electric motor 16, and the oil scattered from the rotor 80 by centrifugal force reaches the coil 96. As can be done, the space formed inside the housing 70 corresponds to the “lubricating oil guide mechanism” in the ninth aspect of the invention.

Embodiment 2. FIG.
[Structure of Embodiment 2]
Next, a second embodiment of the present invention will be described with reference to FIG. 1 and FIG. In the system of the present embodiment, the oil pump 50 that supplies oil to the electrically driven supercharger 10 is an electric pump provided separately from the oil pump of the internal combustion engine, and the ECU 60 is the above-described diagram. 5 is different from the system of the first embodiment in that a routine shown in FIG. 5 described later is executed in addition to the routine shown in FIG.

[Features of Embodiment 2]
When the oil pump 50 is an oil pump of the internal combustion engine 20, oil cannot be supplied to the electrically driven supercharger 10 after the internal combustion engine 20 is stopped. That is, in this case, the electric motor 16 cannot be cooled after the internal combustion engine 20 is stopped. However, when the internal combustion engine 20 is stopped immediately after high-speed traveling, the electric motor 16 may become hot after the stop.

  In this case, it is desirable to continue cooling the electric motor 16 even after the internal combustion engine 20 is stopped. Therefore, in the system of the present embodiment, the oil pump 50 is an electric pump, and after the internal combustion engine 20 is stopped, the cooling of the electric motor 16 with oil is continued until the temperature of the electric motor 16 sufficiently decreases.

[Specific Processing in Second Embodiment]
FIG. 5 is a flowchart of a routine executed by the ECU 60 in the present embodiment in order to realize the above function. In the routine shown in FIG. 5, it is first determined whether or not the internal combustion engine 20 is stopped (step 130). As a result, if it is determined that the internal combustion engine 20 is not stopped, it is determined that it is not necessary to continue this routine, and then the current processing cycle is immediately terminated.

In step 130, if the internal combustion engine 20 is determined to have stopped, then, based on the output of the motor stator temperature sensor 68, whether the temperature of the motor 16 has reached the cooling determination temperature T _B is determined (Step 132).

If immediately after the high-speed running such as internal combustion engine 20 is stopped, in step 132, the temperature of the electric motor 16 is judged to have reached the cooling determination temperature T _B. In this case, it is desirable to perform cooling of the electric motor 16 with oil from the viewpoint of reducing the thermal environment of the electric motor 16. To address this need, in step 132, if the temperature of the electric motor 16 is determined to exceed the cooling determination temperature T _B, first, the driving of the oil pump 50 and the motor 16 is commanded (step 134, 136 Thereafter, the jet of oil toward the gap 96 is commanded (step 138).

  When the oil pump 50 is operating, oil is supplied to the bearings 82 and 84 of the electric motor 16. When the electric motor 16 is operating in this state, the oil that has flowed out of the bearings 82 and 84 scatters due to centrifugal force, and cools the periphery of the stator 94 and the coil 96. Furthermore, if oil is jetted during operation of the electric motor 16, the gap 96 between the stator 94 and the rotor 80 is also cooled by the oil. For this reason, according to the process of the said steps 134-138, the electric motor 16 can be cooled efficiently.

If the temperature of the electric motor 16 is an internal combustion engine 20 under sufficiently low status is stopped, in step 132, the temperature of the electric motor 16 is determined not to reach the cooling determination temperature T _B. The same determination is made even when the electric motor 16 is sufficiently cooled by oil after the internal combustion engine 20 is stopped. In this case, since it is not necessary to further cool the electric motor 16, the system is instructed to stop immediately thereafter (step 140).

  As described above, according to the routine shown in FIG. 5, when the electric motor 16 is at a high temperature after the internal combustion engine 20 is stopped, the cooling by the oil can be continued until the temperature is sufficiently lowered. For this reason, according to the system of the present embodiment, the electric motor 16 can be cooled more efficiently than in the case of the first embodiment.

  In the system of this embodiment, since the oil pump 50 is provided independently of the oil pump of the internal combustion engine 20, the oil supply amount to the electrically driven supercharger 10 is changed to the operating state of the internal combustion engine 20. It can be freely controlled without being restricted. When the oil pump 50 is constituted by the oil pump of the internal combustion engine 20, for example, there may occur a situation where a sufficient amount of oil supply to the electrically driven supercharger 10 cannot be ensured when the internal combustion engine 20 is started at a low temperature.

  In the system of the present embodiment, even under such a situation, a sufficient oil supply amount to the electrically driven supercharger 10 can be ensured by increasing the load of the oil pump 50 (electric). In this respect, the system of the present embodiment has a characteristic that damage to the rotating shaft 72 of the electric drive supercharger 10 can be prevented more reliably than the system of the first embodiment.

  In the second embodiment, the oil pump 50 corresponds to the “electric coolant pump” in the seventh invention, and the motor stator temperature sensor 68 corresponds to the “temperature detection means” in the seventh invention. is doing. Further, the ECU 60 executes the processing of step 138 to realize the “post-stop cooling command means” in the seventh aspect of the invention.

Embodiment 3 FIG.
[Configuration of Embodiment 3]
Next, referring to FIG. 1 again, a third embodiment of the present invention will be described. The system of the present embodiment has an oil pump 50 that is independent from the oil pump of the internal combustion engine 20 as in the system of the second embodiment. Further, in the present embodiment, an oil tank communicating with the oil drain portion 109 is also provided separately from the oil tank of the internal combustion engine 20. More specifically, in the system according to the present embodiment, a system for circulating oil inside the internal combustion engine 20 and a system for circulating oil inside the electrically driven supercharger 10 are independent of each other. It is provided as a system.

[Features of Embodiment 3]
In the system of the present embodiment, since the oil circulation system of the internal combustion engine 20 and the oil circulation system of the electrically driven supercharger 10 are independent from each other, different oils can be used in these two circulation systems. For example, low viscosity (for example, 5 W) oil can be used for the oil circulation system of the internal combustion engine 20, and high viscosity (for example, 10 W) oil can be used for the oil circulation system of the electrically driven supercharger 10.

  Compared to the sliding portion formed inside the internal combustion engine 20, the sliding portion formed around the rotating shaft 72 of the electric drive supercharger 10 slides at a higher speed. For this reason, compared with the sliding part of the internal combustion engine 20, the sliding part of the electrically driven supercharger 10 is in an environment in which an oil film of oil is difficult to form. Therefore, the oil that can withstand use in the electrically driven supercharger 10 has higher viscosity than the oil that can withstand use in the internal combustion engine 20 alone.

  For the above reasons, when the oil circulation system of the internal combustion engine 20 and the oil circulation system of the electrically driven supercharger 10 are not independent, high-viscosity oil that can be used in the electrically driven supercharger 10 is used. 20 also needs to be supplied. The resistance at the sliding portion increases as the viscosity of the oil supplied thereto increases. Therefore, the internal combustion engine 20 that receives the supply of the high-viscosity oil that can withstand use in the electric drive supercharger 10 has deteriorated the fuel consumption characteristics due to the high-viscosity oil.

  In the system of this embodiment, low-viscosity oil can be circulated through the internal combustion engine 20, and high-viscosity oil can be circulated through the electrically driven supercharger 10. That is, according to the system of the present embodiment, the internal combustion engine 20 is supplied with oil having a viscosity required by the sliding portion of the internal combustion engine 20, and the electric drive supercharger 10 is supplied with the electric drive supercharger. The oil having the viscosity required by 10 sliding parts can be supplied. For this reason, according to the system of the present embodiment, as compared with a system in which both the internal combustion engine 20 and the electrically driven supercharger 10 must be supplied with the same viscosity oil, without any inconvenience, The fuel consumption characteristics of the internal combustion engine 20 can be improved.

  The oil drain of a turbocharger (turbocharger) usually relies on free fall. On the other hand, in recent years, there is a strong demand for lowering the center of gravity of the internal combustion engine 20, and it is required to lower the mounting position of the supercharger. When oil flowing out from the oil drain portion 109 of the electric drive supercharger 10 is to be collected in the oil tank of the internal combustion engine 20, the mounting position of the electric drive supercharger 10 is as required while ensuring sufficient drain performance. It may be difficult to lower the temperature.

  On the other hand, in the system of the present embodiment, a high degree of freedom is secured with respect to the mounting position of the tank that collects the oil discharged from the electrically driven supercharger 10. For this reason, according to this system, as compared with a system in which the electric drive supercharger 10 and the internal combustion engine 20 share an oil tank, a request for lowering the mounting position of the electric drive supercharger 10 and the electric drive Coexistence with the request | requirement of fully ensuring the oil drain performance of the supercharger 10 is easy.

It is a figure for demonstrating the whole structure of Embodiment 1 of this invention. It is a figure for demonstrating the internal structure of the electric drive supercharger shown in FIG. It is a flowchart of the routine performed in Embodiment 1 of the present invention. It is a diagram showing the relationship between the cooling determination temperature T _B and the allowable upper limit temperature T _A. It is a flowchart of the routine performed in Embodiment 2 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Electric drive supercharger 12 Compressor 14 Turbine 16 Electric motor 20 Internal combustion engine 48 Oil control valve 50 Oil pump 60 ECU (Electric Control Unit)
68 Motor stator temperature sensor 70 Housing 72 Rotating shaft 80 Rotors 82 and 84 Bearing 94 Stator 96 Gap 98 Coils 102 and 104 Bearing communication path 106 Gap cooling path 108 Injection hole

Claims (12)

A compressor for pressurizing the intake air of the internal combustion engine;
A turbine that converts exhaust energy into rotational force of the compressor;
An electric motor disposed between the compressor and the turbine and assisting the rotation of the compressor;
A gap cooling path for injecting coolant into the gap between the rotor and stator of the electric motor,
The electrically driven supercharger cooling system, wherein the gap cooling path extends on the compressor side with respect to the electric motor. A flow rate control means for controlling the flow rate of the coolant injected into the gap from the gap cooling path;
Fuel supply state detection means for detecting the fuel supply state to the internal combustion engine;
An injection prohibiting means for prohibiting the injection of the coolant from the cooling path into the gap when the fuel is constantly supplied to the internal combustion engine and when the amount of fuel supply to the internal combustion engine is increasing;
The electric drive supercharger cooling system according to claim 1.   Injecting command means for instructing injection of coolant from the cooling path to the gap when the fuel supply amount to the internal combustion engine is decreasing and when the fuel supply to the internal combustion engine is cut off The electrically driven supercharger cooling system according to claim 2. The fuel supply state detection means includes a decrease speed detection means for detecting a decrease speed of the fuel supply amount,
The injection command means includes
An injection amount calculating means for calculating an injection amount of the coolant into the gap based on a decrease rate of the fuel supply amount;
The electric drive supercharger cooling system according to claim 3, further comprising: a flow rate control unit that controls the flow rate control unit so that the calculated injection amount is injected. Temperature detecting means for detecting the temperature of the electric motor;
Forced cooling command means for commanding injection of coolant from the gap cooling path to the gap when the temperature of the electric motor has reached the cooling determination temperature;
The electric drive supercharger cooling system according to any one of claims 1 to 4, further comprising: Temperature detecting means for detecting the temperature of the electric motor;
Energization cut command means for cutting energization to the motor when the temperature of the motor has reached an allowable upper limit temperature higher than the cooling determination temperature;
The electrically driven supercharger cooling system according to any one of claims 1 to 5, further comprising: An electric coolant pump provided to supply coolant to the gap cooling path;
Temperature detecting means for detecting the temperature of the electric motor;
A post-stop cooling command means for commanding injection of coolant from the gap cooling path to the gap when the temperature of the electric motor has reached a cooling determination temperature after the internal combustion engine is stopped;
The electrically driven supercharger cooling system according to any one of claims 1 to 6, further comprising:   A system for supplying the lubricating oil and a system for supplying the cooling liquid so that the lubricating oil supplied to the internal combustion engine and the cooling liquid supplied to the gap cooling path are not mixed with each other. Are provided as systems independent of each other, and the electrically driven supercharger cooling system according to any one of claims 1 to 7. A bearing for rotatably holding the rotor;
A bearing communication path for supplying lubricating oil to the bearing;
A lubricating oil guide mechanism for guiding the lubricating oil supplied to the bearing to the periphery of a coil provided in the stator;
The electrically driven supercharger cooling system according to any one of claims 1 to 8, further comprising:   10. The gap cooling path includes an injection hole that opens in a direction in which the cooling liquid is jetted in a direction parallel to the gap and faces an end of the gap. The electrically driven supercharger cooling system according to claim 1. A compressor for pressurizing the intake air of the internal combustion engine;
A turbine that converts exhaust energy into rotational force of the compressor;
An electric motor disposed between the compressor and the turbine and assisting the rotation of the compressor;
A gap cooling path for injecting coolant into the gap between the rotor and stator of the electric motor;
A flow rate control means for controlling the flow rate of the coolant injected into the gap from the gap cooling path;
Fuel supply state detection means for detecting the fuel supply state to the internal combustion engine;
An injection prohibiting means for prohibiting the injection of the coolant from the cooling path into the gap when the fuel is constantly supplied to the internal combustion engine and when the amount of fuel supply to the internal combustion engine is increasing;
An electrically driven supercharger cooling system comprising:   Injecting command means for instructing injection of coolant from the cooling path to the gap when the fuel supply amount to the internal combustion engine is decreasing and when the fuel supply to the internal combustion engine is cut off The electrically driven supercharger cooling system according to claim 11.

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