JP2007224899A - Motor-driven supercharger - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a motor-driven supercharger without deteriorating efficiency in a compressor even if also serving as the cooling of an electric motor and a diffuser part by lengthening a continuous operation time by effectively restraining a temperature rise in the electric motor, by properly exhibiting a temperature rise restraining effect of the electric motor by a coolant. <P>SOLUTION: This motor-driven supercharger has a coolant flow rate adjusting means (a flow rate adjusting part 37 and a control part 40) capable of adjusting a flow rate of the coolant. By the flow rate adjusting part 37 and the control part 40, the flow rate of the coolant 41 is set to a first flow rate (a large flow rate) of cooling the electric motor 20 in a state of being the predetermined temperature higher but not lower than zero in a temperature difference of subtracting the temperature of the coolant 41 from the temperature of the electric motor 20, and the flow rate of the coolant 41 is set to a flow rate lower than the first flow rate, that is, a second flow rate (a small flow rate) of restraining heating action to the electric motor 20 in a state of being lower than the predetermined temperature not lower than zero in the temperature difference. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a supercharger equipped with an electric motor provided with an electric motor that assists rotational driving of a compressor in a supercharger that is driven by exhaust gas of an internal combustion engine to compress and supercharge intake air.

  In order to improve the performance of an internal combustion engine, a supercharger (also referred to as “turbocharger”) that is driven by exhaust gas of the internal combustion engine and compresses intake air to supercharge is widely used. In addition, a turbocharger in which acceleration response is improved by incorporating an electric motor coaxially with the shaft of the supercharger and assisting acceleration of the rotational drive of the compressor is also used. Such a supercharger having an electric assist function by an electric motor is called a supercharger with an electric motor.

FIG. 4 is a diagram showing a schematic configuration of a conventional supercharger 50 with an electric motor. On the exhaust passage side of the supercharger 50, a turbine impeller 52 and a turbine housing 51A surrounding the turbine impeller 52 are disposed. The turbine housing 51 </ b> A has a scroll chamber 63 formed around the turbine impeller 52, and the scroll chamber 63 communicates with the turbine impeller 52 via an annular gas passage 64.
Further, an exhaust port 65 concentric with the turbine impeller 52 is formed at the center of the turbine housing 51A.

A compressor impeller 53 and a compressor housing 51B surrounding the compressor impeller 53 are disposed on the intake passage side of the supercharger with motor 50.
The compressor housing 51B has a scroll chamber 66 formed around the compressor impeller 53, and the scroll chamber 66 communicates with the compressor impeller 53 via a diffuser portion 67 formed in an annular shape.
Further, the compressor housing 51B is formed with an air inlet 68 concentric with the compressor impeller 53 at the center.

The turbine impeller 52 and the compressor impeller 53 are connected by a shaft 54. The shaft 54 is rotatably supported by a bearing 55 built in the center housing 51C.
Further, the center housing 51 </ b> C incorporates an electric motor 58 having a rotor 56 coaxially connected to the shaft 54 and a stator 57 disposed around the rotor 56.

  In the supercharger 50 with the motor configured as described above, when exhaust gas from the internal combustion engine (engine) is introduced into the scroll chamber 63, the exhaust gas flows to the exhaust port 65 via the annular gas flow path 64. In the process of passing through the turbine impeller 52, the turbine impeller 52 is rotated. Then, the compressor impeller 53 connected to the turbine impeller 52 via the shaft 54 is rotationally driven, and at the same time, the rotational drive is assisted by the electric motor 58, and the air taken in from the intake port by the compressor impeller 53 is accelerated. The accelerated air is depressurized and pressurized in the process of passing through the diffuser portion 67, is introduced into the scroll chamber 66, is discharged from a discharge portion (not shown), and is supplied to the internal combustion engine.

In such a supercharger 50 with an electric motor, the electric motor 58 rotates at high speed during operation of the supercharger and self-heats due to windage loss and eddy current loss. Further, since high-temperature exhaust gas flows through the turbine, the electric motor 58 becomes hot due to heat conduction from the turbine impeller 52 to the shaft 54 and from the shaft 54 to the rotor 56 of the electric motor 58.
When the electric motor 58 becomes high temperature, an internal permanent magnet is demagnetized or the efficiency of the electric motor 58 is reduced. In addition, when the electric motor 58 becomes high temperature and reaches the upper limit temperature, the electric motor 58 cannot be driven, and thus the electric assist function cannot be used.

Therefore, in the supercharger 50, as shown in FIG. 4, a turbine side coolant flow path 60 is formed in a turbine side portion of the center housing, and the coolant is caused to flow through the turbine side coolant flow path 60. The peripheral part is cooled to suppress heat transfer to the motor side.
Further, in the supercharger 50, a motor side coolant flow path 61 is formed so as to surround the motor 58, and the coolant 62 is caused to flow through the motor side coolant flow path 61 to increase the temperature of the motor 58 by the cooling action. It is configured to suppress.
The turbine-side coolant flow path 60 and the motor-side coolant flow path 61 communicate with each other through a communication path (not shown) formed in the center housing. It comes to flow.

By the way, there is a system in which a coolant channel system is independently provided on the turbine side and the motor side, and the coolant flows independently. However, from the viewpoint of ease of design, manufacture, etc. In addition, a method of using a common coolant on the turbine side and the motor side is widely adopted.
In the supercharger with an electric motor described above, radiator water is generally used as the cooling liquid 62 flowing through the cooling liquid channels 60 and 61. In this case, the temperature of the cooling liquid 62 is 80 ° C. to 80 ° C. It is about 120 ° C. In general, a supercharger with an electric motor is designed based on the idea that it is not necessary to always drive the electric motor, and the electric assist effect may be exhibited for a certain period of time. For this reason, the cooling capacity of the cooling liquid 62 and the temperature increase of the electric motor 58 are not balanced, and even if the cooling liquid flows through the electric motor side cooling liquid flow path 61, the temperature of the electric motor 58 does not decrease. The temperature of the electric motor 58 rises.
That is, in the supercharger 50, the coolant 62 is caused to flow through the motor-side coolant flow path 61 to suppress the temperature rise of the motor 58, and the motor 58 reaches the upper limit temperature (for example, 180 ° C.) during operation of the motor 58. The time to start (continuous operation time) is lengthened.

  As such a supercharger with an electric motor, various proposals such as the following Patent Documents 1 and 2 have been made.

JP 2004-3420 A JP 2000-130176 A

As described above, in the supercharger with an electric motor, the coolant flowing through the coolant flow paths 60 and 61 is generally radiator water. In this case, the temperature of the coolant is 80 ° C. to 120 ° C. It is about ℃.
For this reason, when the temperature of the electric motor 58 is higher than the temperature of the coolant as in the rated operation, there is an effect of suppressing the temperature increase of the electric motor 58.
However, when the temperature of the electric motor 58 is lower than the temperature of the coolant 62 immediately after the start of operation or in a partial load state where the rotational speed is lower than that of the rated operation, the motor 58 is heated by the coolant 62 conversely. The temperature difference up to the upper limit temperature of 58 is reduced. That is, in this case, the coolant 62 acts in the direction of shortening the continuous operation time of the electric motor 58 and exhibits a function completely opposite to the original purpose.

In addition, in the Japanese Patent Application No. 2005-233772, the applicant of the present invention is provided with a motor having a cooling structure in which a coolant flow path is provided at a position that surrounds the motor and is adjacent to the diffuser unit, and has both the cooling function of the motor and the diffuser unit. I applied for a turbocharger.
Thus, in the supercharger with an electric motor that serves both for cooling the electric motor and the diffuser part, in a partial load where the compressor discharge temperature is lower than the coolant temperature, the coolant having a high temperature heats the diffuser part having a low temperature.
As a result, the discharge air of the compressor is also heated, and the efficiency of the compressor may be reduced.

  The present invention has been made in view of such circumstances, and by appropriately exerting the effect of suppressing the temperature rise of the motor by the coolant, the temperature rise of the motor is effectively suppressed and the continuous operation time is lengthened. An object of the present invention is to provide a supercharger with an electric motor that can reduce the efficiency of the compressor even when the electric motor and the diffuser section are also cooled.

In order to solve the above problems, the supercharger with an electric motor of the present invention employs the following means.
That is, the supercharger with an electric motor according to the present invention includes an electric motor for accelerating the rotation of the compressor impeller in a center housing disposed between the turbine housing and the compressor housing, and the cooling in the center housing. An electric motor-side coolant flow path for circulating the liquid to cool the electric motor, and a coolant common to the electric motor-side coolant flow path are circulated to cool the turbine impeller side portion of the center housing A supercharger with an electric motor having a turbine-side coolant flow path is provided with a coolant flow rate adjusting means capable of adjusting the flow rate of the coolant.

  The cooling liquid flow rate adjusting means cools the electric motor at a flow rate of the cooling liquid in a state where a temperature difference obtained by subtracting the temperature of the cooling liquid from the temperature of the electric motor is equal to or higher than a predetermined temperature of zero or more. A second flow rate that suppresses the heating action on the electric motor when the temperature difference is lower than a predetermined temperature of zero or more and the flow rate of the coolant is smaller than the first flow rate. It is characterized by setting to.

In this manner, the coolant flow rate adjusting means suppresses the heating action on the motor by reducing the coolant flow rate when the temperature difference obtained by subtracting the coolant temperature from the motor temperature is lower than a predetermined temperature of zero or more. Therefore, the heating of the electric motor by the coolant is minimized.
Further, in a partial load state where the temperature of the motor is low and the discharge air temperature of the compressor is lower than the temperature of the motor, the motor is cooled by the discharge air flowing from the compressor side to the motor side.
The turbine side of the center housing is adjacent to the turbine impeller into which the exhaust gas flows, and becomes hot regardless of the operating state of the electric motor. Therefore, the minimum coolant necessary for cooling the turbine side must flow. . In this respect, in the coolant flow rate adjusting means, the coolant at the second flow rate is allowed to flow even when the temperature of the electric motor is low. Can be maintained.
On the other hand, in a state where the temperature difference obtained by subtracting the coolant temperature from the motor temperature is equal to or higher than a predetermined temperature of zero or more, the coolant flow rate is set to the first flow rate for cooling the motor. This suppresses the temperature rise of the electric motor.
Thus, since the temperature rise suppression effect of the electric motor by the coolant can be appropriately exhibited, the temperature rise of the electric motor can be effectively suppressed. For this reason, it is possible to lengthen the time until the operation upper limit temperature is reached. That is, the continuous operation time of the electric motor can be extended.
Therefore, the effect of the electric assist by the electric motor can be maximized.

  In addition, even in a supercharger with a motor having a cooling structure that combines both the cooling function of the electric motor and the diffuser part, the flow rate of the coolant is controlled as described above, so that at the time of partial load of the electric motor Since the cooling water has the second flow rate and does not heat the compressor discharge air, the efficiency of the compressor does not decrease.

  Moreover, in the supercharger with an electric motor according to the present invention, the coolant flow rate adjusting means sets the coolant flow rate to the second flow rate when the temperature difference increases to a first temperature difference greater than zero. From the first flow rate to the first flow rate, and when the temperature difference is less than or equal to zero and less than a second temperature difference less than the first temperature difference, the coolant flow rate is changed from the first flow rate to the first flow rate. Switching to the second flow rate is a feature.

Thus, when the flow rate of the coolant is switched from the second flow rate to the first flow rate, it is switched at the first temperature difference, and when the coolant flow rate is switched from the second flow rate to the first flow rate, it is smaller than the first temperature difference. Since switching is performed at the second temperature difference and hysteresis is provided, frequent switching operation (chattering phenomenon) can be suppressed.
In addition, since the second temperature difference serving as a reference for the reverse operation for switching from the first flow rate to the second flow rate is set to zero or more, the second temperature difference is always set when the motor temperature is lower than the coolant temperature. Flowing coolant flows. For this reason, the heating of the electric motor by a cooling fluid is suppressed reliably.

  Further, in the supercharger with an electric motor according to the present invention, the coolant flow rate adjusting means includes an on-off valve and a fixed orifice provided in parallel on a coolant supply line for supplying the coolant to the center housing, A controller that controls the on-off valve based on the temperature of the electric motor and the temperature of the coolant, and the flow rate of the coolant is the first flow rate when the on-off valve is open, and the on-off valve is The flow rate of the coolant is the second flow rate in the closed state.

Thus, since the first flow rate and the second flow rate are controlled by the on-off valve and the fixed orifice, it is easy to control the flow rate of the coolant.
Other objects and advantageous features of the present invention will become apparent from the following description with reference to the accompanying drawings.

  According to the present invention, it is possible to effectively suppress the temperature rise of the electric motor by extending the effect of suppressing the temperature rise of the electric motor by the coolant, and to increase the continuous operation time. Even when cooling is performed, an excellent effect that the efficiency of the compressor is not reduced can be obtained.

  Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In addition, the same code | symbol is attached | subjected to the common part in each figure, and the overlapping description is abbreviate | omitted.

[First Embodiment]
The first embodiment of the present invention will be described below.
FIG. 1 is a diagram showing a schematic configuration of a supercharger with an electric motor according to a first embodiment of the present invention. As shown in FIG. 1, the supercharger 10 with an electric motor includes elements such as a turbine impeller 2, a turbine housing 4, a shaft 12, a compressor impeller 6, a compressor housing 8, an electric motor 20, and a center housing 14.

A turbine impeller 2 that is rotationally driven by the exhaust gas G of the internal combustion engine and a turbine housing 4 that surrounds the turbine impeller 2 are disposed on the exhaust passage side.
The turbine housing 4 has a scroll chamber 9 formed around the turbine impeller 2, and the scroll chamber 9 communicates with the turbine impeller 2 through an annular gas passage 11.
The turbine housing 4 is formed with an exhaust port 17 concentric with the turbine impeller 2 at the center.

A compressor impeller 6 that compresses intake air and a compressor housing 8 that surrounds the compressor impeller 6 are disposed in the intake side passage.
The compressor housing 8 includes a scroll chamber 21 that is formed in an annular shape around the compressor impeller 6 and discharges the compressed air A.
An annular diffuser portion 25 extending radially outward from the compressor impeller 6 outlet is formed between the compressor impeller 6 outlet and the scroll chamber 21 so as to communicate therewith. Thus, the compressor impeller 6 is accelerated. The air A is decelerated and pressurized and guided to the scroll chamber 21.
The compressor housing 8 is formed with an air inlet 27 concentric with the compressor impeller 6 at the center.

The turbine impeller 2 and the compressor impeller 6 are connected by a shaft 12, and the shaft 12 is rotatably supported by a bearing 19 built in the center housing 14.
The turbine housing 4 and the center housing 14 are connected by a coupling 3, and the compressor housing 8 and the center housing are connected by a bolt 5.

  The electric motor 20 is incorporated in the center housing 14 and is disposed at a position adjacent to the compressor impeller 6, and is connected to the shaft 12 coaxially and is a rotor 20 </ b> A (rotor) made of a permanent magnet that rotates together with the shaft 12. It is comprised from the stator 20B (stator) which consists of a coil arrange | positioned around the rotor 20A.

The center housing 14 includes an oil supply path 22 for supplying the lubricating oil 42 to the bearing 19, and an oil discharge path 24 for discharging the lubricating oil 42 that has passed through the bearing 19 and lubricated and cooled the bearing 19. Is formed.
The oil supply path 22 is supplied with, for example, a lubricating oil 42 at around 80 ° C. by a lubricating oil pump (not shown) installed outside.

A disc-shaped seal plate 29 having an opening at the center is interposed between the center housing 14 and the compressor housing 8. The inner diameter of the opening of the seal plate 29 is smaller than the outer diameter of the compressor impeller 6, and the portion on the inner peripheral side of the seal plate 29 and the rear surface of the compressor impeller 6 are opposed to each other with a slight gap. For this reason, the outlet side of the compressor impeller 6 and the space in which the rotor 20A is provided communicate with each other, and a part of the discharge air from the compressor impeller 6 flows into the electric motor 20 side.
In addition, in this embodiment, although the flow-path formation member 16 and the seal plate 29 are comprised separately, the member which comprised these integrally may be sufficient.

The center housing 14 includes a housing main body 15 and a flow path forming member 16, and has an electric motor side coolant flow path 34 between the housing main body 15 and the flow path forming member 16.
The flow path forming member 16 has an annular recess 16a for circulating the coolant, is formed in a ring shape as a whole, and is fitted into and inserted into the housing main body 15. An electric motor side coolant flow path 34 through which the coolant 41 flows is defined by the housing main body 15 and the annular recess 16 a of the flow path forming member 16.
The portion of the annular recess 16a on the electric motor side is formed in a fin shape, thereby improving the efficiency of heat conduction.
An O-ring 31 is interposed between the housing body 15 and the flow path forming member 16, and the space between the O-ring 31 is kept watertight.

The motor-side coolant flow path 34 extends in the circumferential direction in the center housing 14 and is formed in an annular shape, and a coolant 41 for cooling the motor 20 is circulated therein.
The motor-side coolant flow path 34 may be formed so as to make a complete round of the outer periphery of the motor 20, or may be formed in a C shape when viewed from the axial direction of the shaft 12.

Connected to the center housing 14 is a coolant supply line 32 that supplies a coolant 41 to the motor-side coolant flow path 34.
A coolant pump (not shown) is connected to the upstream side of the coolant supply line 32 so that the coolant 41 is fed. In the present embodiment, the coolant 41 is radiator water, and its temperature is about 80 ° C to 120 ° C.

An annular turbine-side coolant flow path 35 is formed on the turbine housing 2 side of the center housing 14 so as to surround the shaft 12.
The turbine-side coolant flow path 35 may be formed so as to make a complete round around the shaft 12, or may be formed in a C shape when viewed from the axial direction of the shaft 12.
Further, the turbine side coolant flow path 35 communicates with the motor side coolant flow path 34 through a communication path (not shown) formed in the center housing 14, and has passed through the motor side coolant flow path 34. The cooling liquid 41 flows into the turbine side cooling liquid flow path 35 through the communication path. That is, the supercharger with electric motor 10 is configured such that a common coolant 41 flows through the motor-side coolant channel 34 and the turbine-side coolant channel 35.
A coolant discharge line 33 for discharging the coolant 41 from the turbine side coolant flow path 35 is connected to the center housing 14.

The supercharger with electric motor 10 according to the present embodiment includes a flow rate adjusting unit 37 and a control unit 40.
In the present embodiment, the flow rate adjusting unit 37 includes an on-off valve 38 and a fixed orifice 39 arranged in parallel on the coolant supply line 32, and the flow rate of the coolant 41 is the first when the on-off valve 38 is open. The flow rate is set to a flow rate (hereinafter referred to as a large flow rate), and the flow rate of the coolant 41 is set to a second flow rate (hereinafter referred to as a small flow rate) when the on-off valve 38 is closed. That is, the flow rate of the coolant 41 supplied to the motor-side coolant flow path 34 is switched between a large flow rate and a small flow rate by opening and closing the on-off valve 38.
The control unit 40 has a function of controlling the opening / closing of the on-off valve 38 based on the coolant temperature and the motor temperature. The controller 40 is supplied with a coolant temperature measured by a radiator water thermometer (not shown) and a temperature signal of an electric motor temperature measured by an electric motor thermometer (not shown). Yes.
In this embodiment, the flow rate of the coolant 41 is increased by the flow rate adjusting unit 37 and the control unit 40 when the temperature difference obtained by subtracting the temperature of the coolant 41 from the temperature of the electric motor 20 is equal to or higher than a predetermined temperature of zero or more. In the state where the temperature difference is lower than a predetermined temperature of zero or more, the flow rate of the coolant 41 is set to a small flow rate. That is, in the present embodiment, the flow rate adjusting unit 37 and the control unit 40 function as a coolant flow rate adjusting unit that can adjust the flow rate of the coolant. In the present specification, hereinafter, the temperature difference between the electric motor 20 and the cooling liquid 41 means a temperature difference obtained by subtracting the temperature of the cooling liquid 41 from the temperature of the electric motor 20.

FIG. 2 is a diagram for explaining the flow rate control of the coolant 41 by the flow rate adjusting unit 37 and the control unit 40. In this figure, the horizontal axis represents the difference between the motor temperature and the coolant temperature, and the vertical axis represents the flow rate of the coolant 41 supplied to the motor side coolant channel 34.
As shown in this figure, the flow rate of the cooling liquid 41 when the temperature difference between the electric motor 20 and the cooling liquid 41 is increased to be greater than or equal to the first temperature difference (T1) greater than zero by the flow rate adjusting unit 37 and the control unit 40. Switch from small flow to large flow. Further, when the temperature difference between the electric motor 20 and the coolant 41 is greater than or equal to zero and less than the second temperature difference (T2) smaller than the first temperature difference (T1), the flow rate of the coolant 41 is increased. Switch from low to low flow.
The first temperature difference (T1) is 4 ° C., for example, and the second temperature difference (T2) is 2 ° C., for example. Note that the second temperature difference (T2) may be zero.

The large flow rate is set to a flow rate sufficient to suppress the temperature rise of the electric motor 20 due to the cooling action of the coolant 41 or a flow rate higher than that.
In a state where the temperature of the electric motor 20 is lower than the temperature of the cooling liquid 41, it is necessary to suppress the heating action of the cooling liquid 41 on the electric motor 20. On the other hand, the turbine side of the center housing 14 is adjacent to the turbine impeller 2 into which the exhaust gas G flows, and becomes a high temperature regardless of the operating state of the electric motor 20, so that the minimum cooling required for cooling the turbine side is concerned. The liquid 41 must be poured. Therefore, the small flow rate is a flow rate smaller than the large flow rate, and is a minimum flow rate that suppresses the heating action on the electric motor 20 and can maintain the cooling of the center housing 14 on the turbine side to the minimum.

Next, operation | movement of the supercharger 10 with an electric motor comprised as mentioned above is demonstrated.
In the supercharger with electric motor 10, when the exhaust gas G from the internal combustion engine (engine) is introduced into the scroll chamber 9, the exhaust gas G flows to the exhaust port 17 through the annular gas flow path 11, thereby causing the turbine impeller 2 to flow. The turbine impeller 2 is rotated in the process of passing.
Then, the compressor impeller 6 connected to the turbine impeller 2 via the shaft 12 is rotationally driven, and at the same time, the rotational drive is assisted by the electric motor 20 to accelerate the air A taken in from the intake port 27 by the compressor impeller 6. .
The accelerated air A is depressurized and pressurized in the process of passing through the diffuser section 25, is introduced into the scroll chamber 21, is discharged from a discharge section (not shown), and is supplied to the internal combustion engine.

The coolant 41 is supplied from the coolant supply line 32 to the motor-side coolant channel 34 and the turbine-side coolant channel 35.
Immediately after the start of operation of the electric motor 20 or at the time of partial load, when the temperature difference between the electric motor 20 and the cooling water 41 is lower than the first temperature difference (T1), cooling is performed by the flow rate adjusting unit 37 under the control of the control unit 40. The flow rate of the liquid 41 is set to a small flow rate. For this reason, the heating effect | action with respect to the electric motor 20 by the cooling fluid 41 is suppressed to the minimum.
Further, in a partial load state where the temperature of the electric motor 20 is low and the discharge air temperature of the compressor is lower than the temperature of the electric motor 20, the electric motor 20 is cooled by the discharge air flowing from the compressor side to the electric motor 20 side. For this reason, the temperature of the electric motor 20 is kept at a low temperature.

  When the electric motor 20 enters a steady operation state, the electric motor temperature rises, and the temperature difference between the electric motor 20 and the coolant 41 increases to the first temperature difference (T1) or more, the flow rate is adjusted under the control of the control unit 40. The flow rate of the coolant 41 is switched from a small flow rate to a large flow rate by the unit 37. For this reason, the temperature rise of the electric motor 20 is suppressed by the cooling action of the coolant 41.

  Further, when the temperature of the motor decreases and the temperature difference between the motor 20 and the coolant 41 decreases below the second temperature difference (T2), the coolant 41 is controlled by the flow rate controller 37 under the control of the controller 40. Is switched from a large flow rate to a small flow rate. Then, the heating action on the electric motor 20 by the coolant 41 is suppressed to a minimum, and the electric motor 20 is cooled by the discharge air flowing from the compressor side to the electric motor 20 side, so that the temperature of the electric motor 20 is kept low.

Next, the operation and effect of the supercharger with electric motor 10 according to the present embodiment will be described.
According to the supercharger 10 with the electric motor according to the present embodiment, the temperature difference between the electric motor 20 and the cooling liquid 41 is lower than a predetermined temperature of zero or more by the flow rate adjusting unit 37 and the control unit 40 (cooling liquid flow rate adjusting means). In the state, since the flow rate of the cooling liquid 41 is set to a small flow rate, the heating action on the electric motor 20 by the cooling liquid 41 is minimized.
In the state of partial load where the temperature of the electric motor 20 is low and the discharge air temperature of the compressor is lower than the temperature of the electric motor 20, the electric motor 20 is cooled by the discharge air flowing into the electric motor 20 from the compressor side. The temperature of 20 can be kept low.
Further, even when the temperature of the electric motor 20 is low, a small flow rate of the coolant 41 is allowed to flow, so that a constant flow rate of the coolant 41 is caused to flow through the turbine side coolant channel 35 to maintain cooling of the center housing 14 on the turbine side. it can.
On the other hand, in the state where the temperature difference between the electric motor 20 and the coolant 41 is equal to or higher than a predetermined temperature of zero or more, the flow rate of the coolant 41 is set to a large flow rate. It is suppressed.
Thus, since the temperature rise suppression effect of the electric motor 20 by the coolant 41 can be exhibited appropriately, the temperature rise of the electric motor 20 can be effectively suppressed. For this reason, it is possible to lengthen the time until the operation upper limit temperature is reached. That is, the continuous operation time of the electric motor 20 can be lengthened.
Therefore, the effect of the electric assist by the electric motor 20 can be maximized.

Further, according to the supercharger 10 with the electric motor according to the present embodiment, when the flow rate of the coolant 41 is switched from the small flow rate to the large flow rate, the switching is performed at the first temperature difference (T1), and the large flow rate is switched to the small flow rate. In some cases, the switching is performed at the second temperature difference (T2) smaller than the first temperature difference and the hysteresis is provided, so that frequent switching operation (chattering phenomenon) can be suppressed.
Further, since the second temperature difference (T2) serving as a reference for the reverse operation for switching from the large flow rate to the small flow rate is set to zero or more, the small flow rate is always set when the temperature of the electric motor 20 is lower than the temperature of the coolant 41. The coolant 41 flows. For this reason, the heating effect | action with respect to the electric motor 20 by the cooling fluid 41 can be suppressed reliably.

  Further, since the small flow rate and the large flow rate are controlled by the on-off valve 38 and the fixed orifice 39, the flow rate control of the coolant 41 is easy.

[Second Embodiment]
Hereinafter, a second embodiment of the present invention will be described.
FIG. 3 is a diagram showing a schematic configuration of a supercharger 10 with an electric motor according to the second embodiment of the present invention.
In the present embodiment, the portion of the flow path forming member 16 on the diffuser portion 25 side has a structure that allows heat exchange between the coolant 41 flowing through the motor-side coolant flow channel 34 and the air A flowing through the diffuser portion 25. ing. Moreover, the site | part by the side of the diffuser part 25 of the flow-path formation member 16 is formed in fin shape, and the heat transfer area is expanded and the efficiency of heat conduction is improved.
The thickness of the member constituting the heat transfer portion is set so that the heat exchange between the coolant and the diffuser portion 25 can be sufficiently performed.
With such a structure, heat exchange is performed between the cooling liquid 41 flowing through the cooling liquid flow path 34 and the electric motor 20 and between the cooling liquid 41 and the diffuser section 25, and both the electric motor 20 and the diffuser section 25 are connected. It is designed to cool.
That is, the supercharger 10 with the electric motor according to the present embodiment is a supercharger with an electric motor having a cooling structure having both the cooling functions of the electric motor 20 and the diffuser unit 25.

  The structure of the other part of the supercharger with motor 10 according to the present embodiment is the same as that of the first embodiment described above.

Next, the operation / action / effect of the supercharger with electric motor 10 according to the present embodiment will be described.
Also in the supercharger 10 with the electric motor according to the present embodiment, the turbine impeller 2 is rotated by the exhaust gas G from the internal combustion engine, and the compressor impeller 6 connected thereto is rotationally driven as in the first embodiment. The air A is compressed and supplied to the internal combustion engine. At this time, the rotation of the compressor impeller 6 is assisted by the electric assist by the electric motor 20.

The coolant 41 is supplied from the coolant supply line 32 to the motor-side coolant channel 34 and the turbine-side coolant channel 35. The flow rate control of the coolant by the flow rate adjusting unit 37 and the control unit 40 at this time is the same as that in the first embodiment.
That is, immediately after the start of operation of the electric motor 20 or at the time of partial load, when the temperature difference between the electric motor 20 and the cooling water 41 is lower than the first temperature difference (T1), the flow rate adjustment unit 37 is controlled under the control of the control unit 40. Thus, the flow rate of the coolant 41 is set to a small flow rate. Further, when the temperature difference between the electric motor 20 and the cooling liquid 41 increases to a first temperature difference (T1) greater than zero, the flow rate of the cooling liquid 41 is switched from a small flow rate to a large flow rate. Further, when the temperature difference between the electric motor 20 and the coolant 41 is not less than zero and decreases to the second temperature difference (T2) smaller than the first temperature difference (T1), the flow rate of the coolant 41 is large. The flow rate is switched to a small flow rate.

  By controlling the flow rate of the coolant 41 as described above, the coolant 41 flowing through the motor side cooling flow path 34 is a small flow rate even at the partial load where the compressor discharge temperature is lower than the coolant temperature. The cooling liquid 41 does not heat the air flowing through the diffuser part.

  As described above, even in the supercharger with a motor having a cooling structure having both the cooling functions of the electric motor 20 and the diffuser unit 25 as in the present embodiment, the coolant 41 is compressed at the partial load of the electric motor 20. Since the discharge air is not heated, the efficiency of the compressor does not decrease.

  As is apparent from the description of each of the above embodiments, according to the present invention, the temperature rise suppression effect of the motor by the coolant is appropriately exerted, thereby effectively suppressing the temperature rise of the motor and reducing the continuous operation time. While being able to lengthen, even if it serves as cooling of an electric motor and a diffuser part, the outstanding effect that the efficiency fall of a compressor is not caused is acquired.

[Other Embodiments]
In the above embodiment, the bearing 19 of the shaft 12 is disposed on the turbine side and the motor-equipped supercharger in which the electric motor 20 is disposed on the compressor side is targeted, but the scope of application of the present invention is not limited to this, For example, the present invention can also be applied to a supercharger with a motor disclosed in Japanese Patent Application Laid-Open No. 2003-293785, in which a motor is disposed at the center and bearings are disposed on both sides thereof.

  In the above embodiment, the flow rate adjusting unit 37 is configured by the on-off valve 38 and the fixed orifice 39. However, the flow rate adjusting valve may be configured to adjust the large flow rate and the small flow rate.

  In addition, this invention is not limited to the said embodiment, Of course, it can change variously in the range which does not deviate from the summary of this invention.

It is a figure which shows schematic structure of the supercharger with an electric motor concerning 1st Embodiment of this invention. It is a figure explaining flow control of the cooling fluid by a flow control part and a control part. It is a figure which shows schematic structure of the supercharger with an electric motor concerning 2nd Embodiment of this invention. It is a figure which shows schematic structure of the conventional supercharger with an electric motor.

Explanation of symbols

2 Turbine impeller 4 Turbine housing 6 Compressor impeller 8 Compressor housing 9 Scroll chamber 10 Supercharger with motor 11 Annular gas flow path 12 Shaft 14 Center housing 15 Housing body 16 Flow path forming member 16a Annular recess 17 Exhaust port 19 Bearing 20 Electric motor 21 Scroll chamber 20A Rotor 20B Stator 22 Oil supply path 24 Oil discharge path 25 Diffuser section 27 Air inlet 29 Seal plate 31 O-ring 32 Coolant supply line 33 Coolant discharge line 34 Motor side coolant path 35 Turbine side coolant Flow path 37 Flow rate control unit 38 On-off valve 39 Orifice 40 Control unit 41 Coolant 42 Lubricating oil A Air G Exhaust gas

Claims (4)

An electric motor that cools the electric motor by circulating a coolant in the center housing, and includes an electric motor that accelerates and assists rotation of the compressor impeller in a center housing disposed between the turbine housing and the compressor housing. A motor-side excess passage having a liquid flow path and a turbine-side cooling liquid flow path that cools a portion of the center housing on the turbine impeller side by circulating a common cooling liquid with the cooling liquid in the electric motor-side cooling liquid flow path In the machine,
A supercharger with an electric motor comprising a coolant flow rate adjusting means capable of adjusting a flow rate of the coolant.   The cooling liquid flow rate adjusting means is a first flow rate for cooling the electric motor with a flow rate of the cooling liquid in a state where a temperature difference obtained by subtracting the temperature of the cooling liquid from the temperature of the electric motor is equal to or higher than a predetermined temperature of zero or more In a state where the temperature difference is lower than a predetermined temperature of zero or more, the flow rate of the coolant is set to a second flow rate that is smaller than the first flow rate and suppresses the heating action on the motor. The supercharger with an electric motor according to claim 1.   The coolant flow rate adjusting means switches the flow rate of the coolant from the second flow rate to the first flow rate when the temperature difference increases to a first temperature difference greater than zero, and the temperature difference is The flow rate of the coolant is switched from the first flow rate to the second flow rate when the flow rate decreases to zero or more and less than a second temperature difference that is smaller than the first temperature difference. Item 3. A supercharger with an electric motor according to Item 2. The coolant flow rate adjusting means is based on an on-off valve and a fixed orifice provided in parallel on a coolant supply line for supplying the coolant to the center housing, based on the temperature of the motor and the temperature of the coolant. A control unit for controlling the on-off valve,
The flow rate of the coolant is the first flow rate when the on-off valve is open, and the flow rate of the coolant is the second flow rate when the on-off valve is closed. 3. A supercharger with an electric motor according to 3.

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