JP2017150355A - Cooling device for electric supercharger - Google Patents

Abstract

PROBLEM TO BE SOLVED: To efficiently cool oil of an electric supercharger and prevent overcooling.SOLUTION: A cooling device for an electric supercharger includes a bearing, an oil passage, a cooling water passage, a heat exchanger and a control device. The oil passage is communicated with the bearing to circulate oil for oil lubrication of the bearing. The cooling water passage is configured to be a system separate from a cooling water passage of an internal combustion engine to circulate cooling water in a housing of the electric supercharger. The heat exchanger is installed outside the housing. Both of the oil passage and the cooling water passage are connected to the heat exchanger, and heat is exchanged between the oil and the cooling water in the heat exchanger. A passage bypassing the heat exchanger is connected to the cooling water passage. A selector valve for opening/closing the cooling water passage is installed at a portion of the cooling water passage that is bypassed by the bypass passage. When a temperature of the oil is lower than a reference temperature, the control device blocks inflow of the cooling water to the heat exchanger by using the selector valve.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a cooling device for an electric supercharger.

  Since the electric supercharger of an internal combustion engine is likely to rise in temperature due to heat generated by the electric motor, it is necessary to cool the electric motor in order to protect the electric motor. For example, the supercharger disclosed in Patent Document 1 includes a bearing housing in which a cooling water passage for circulating cooling water is formed on the outer periphery side of a bearing filled with grease.

International Publication No. 2014/080501 JP 2012-097613 A JP 2008-280900 A

  In the case where a cooling water passage is provided in the bearing housing and the bearing grease is cooled by the cooling water flowing through the cooling water passage as in the supercharger of Patent Document 1, the grease is cooled via the housing. It will be. However, the supercharger housing is likely to become hot due to heat received from the electric motor, and cooling through the housing may cause insufficient cooling of the grease.

  An object of the present invention is to provide a cooling device for an electric supercharger that is improved so that oil of the electric supercharger can be appropriately cooled.

  The present invention relates to a cooling device for an electric supercharger, which is formed in a housing of the electric supercharger, supports a rotating shaft of the electric supercharger, an oil passage, a cooling water passage, a heat It has an exchanger and a control device. The oil passage is a passage that communicates with the bearing and circulates oil for oil lubrication of the bearing. The cooling water passage is a passage configured in a separate system from the cooling water circuit of the internal combustion engine, and is a passage for circulating the cooling water in the housing of the electric supercharger. The heat exchanger is installed outside the housing. The heat exchanger is configured such that an oil passage and a cooling water passage are connected together, and heat exchange is performed between the oil in the oil passage and the cooling water in the cooling water passage. In addition, a passage that bypasses the heat exchanger is connected to the cooling water passage. More specifically, the bypass passage is connected at one end to a branch portion upstream of the heat exchanger of the cooling water passage, and connected to the junction portion of the cooling water passage downstream of the heat exchanger at the other end. Yes. In addition, a switching valve for opening and closing the cooling water passage is installed between the branch portion of the cooling water passage and the junction with the bypass passage. When the temperature of the oil is lower than the reference, the control device operates the switching valve to block the cooling water from flowing into the heat exchanger.

According to the present invention, the oil for lubricating the bearing is cooled by the cooling water in the heat exchanger installed outside the electric supercharger. Therefore, the oil can be efficiently and sufficiently cooled, and various parts of the electric supercharger can be protected. In addition, when the oil temperature is low, the heat exchange between the oil and the cooling water is stopped by blocking the inflow of the cooling water to the heat exchanger. Thereby, overcooling of the oil can be prevented and friction can be reduced.

1 is a schematic diagram for explaining an overall configuration of a system according to a first embodiment. It is a schematic diagram for demonstrating the structure of the heat exchanger of Embodiment 1. FIG. It is a schematic diagram for demonstrating the structure of the heat exchanger of Embodiment 1. FIG. 6 is a schematic diagram for explaining an overall configuration of a system according to a second embodiment. FIG.

  Embodiments of the present invention will be described below with reference to the drawings. In addition, the same code | symbol is attached | subjected to the element which is common in each figure, and the overlapping description is abbreviate | omitted.

Embodiment 1 FIG.
FIG. 1 is a schematic diagram for explaining the system configuration of the first embodiment. The system shown in FIG. 1 is used by being mounted on a vehicle (automobile). The system in FIG. 1 includes an electric supercharger 10. The electric supercharger 10 is configured to supercharge intake gas supplied to the engine by a compressor wheel 8 connected to one end of a rotating shaft 12. The rotating shaft 12 is supported by bearings 14 and 16. The electric supercharger 10 includes a housing 18 that houses the compressor wheel 8 and holds the bearings 14 and 16.

  A rotor 20 is installed in the housing 18 on the outer peripheral side of the rotary shaft 12. A stator core 22 is installed in the housing 18. A coil 24 is wound around the stator core 22. A cooling water passage 26 through which cooling water flows is formed in the wall portion of the housing 18 on the outer peripheral side of the stator core 22 in order to cool the stator core 22 and the like. Oil passages 28 and 30 connected to the bearings 14 and 16 are formed in the housing 18.

  The cooling water passage 26 is connected to a cooling water passage 32 formed outside the housing 18. The cooling water passage 32 is a passage that is configured in a separate system from the engine cooling water circuit and through which low-temperature cooling water flows. A sub radiator 34 and a water pump 36 are installed in the cooling water passage 32. A heat exchanger 38 is installed downstream of the water pump 36 in the cooling water passage 32.

  A bypass passage 40 that bypasses the heat exchanger 38 is connected to the cooling water passage 32. That is, one end of the bypass passage 40 is connected to the cooling water passage 32 at a branch portion 32 a upstream of the heat exchanger 38 and downstream of the water pump 36. The other end of the bypass passage 40 is connected to the cooling water passage 32 at the junction 32 b downstream of the heat exchanger 38. A switching valve 42 is installed in a portion of the cooling water passage 32 downstream from the branch portion 32 a and upstream from the junction portion 32 b, that is, a portion that can be bypassed by the bypass passage 40. When the switching valve 42 is completely closed by the opening / closing operation of the switching valve 42, the inflow of the cooling water to the heat exchanger 38 is blocked, and the cooling water flows through the bypass passage 40 and bypasses the heat exchanger 38.

  The oil passages 28 and 30 are connected to the oil passage 50. More specifically, the oil passage 50 is branched into two branch passages 50a and 50b in the vicinity of the supply ports 28a and 30a of the oil passages 28 and 30, and the branch passage 50a is connected to the oil passage 28 at the supply port 28a. The branch passage 50b is connected to the oil passage 30 at the supply port 30a. The oil passage 50 is branched into two branch passages 50c and 50d in the vicinity of the oil discharge ports 18a and 18b formed in the housing 18, and the branch passage 50c communicates with the discharge port 18a. It communicates with the discharge port 18b.

  The above-described heat exchanger 38 is installed in the oil passage 50. A temperature sensor 52 is installed near and downstream of the heat exchanger 38 in the oil passage 50. An oil pump 54 for circulating oil in the oil passage 50 is installed further downstream of the oil passage 50.

  2 and 3 are schematic views for explaining the configuration of the heat exchanger 38, and FIG. 3 shows a cross section in the AA direction of FIG. As shown in FIGS. 2 and 3, a cooling water passage 60 that forms part of the cooling water passage 32 and an oil passage 62 that forms part of the oil passage 50 are formed in the heat exchanger 38. ing. The cooling water passage 60 and the oil passage 62 are separated by a partition wall portion 64. Cooling fins 66 are installed in the partition wall 64. The oil that has flowed into the heat exchanger 38 is cooled by the cooling water flowing through the cooling water passage 60 in the vicinity thereof while passing through the oil passage 62 in the heat exchanger 38.

  The oil sufficiently cooled in the heat exchanger 38 installed outside the electric supercharger 10 circulates in the oil passage 50 and is distributed by the branch passages 50a and 50b, and is supplied into the housing 18 from the supply ports 28a and 30a. To the oil passages 28 and 30. Thereafter, the oil is supplied to the bearings 14 and 16, lubricates the bearings 14 and 16, cools the rotary shaft 12 in the housing 18, the surrounding rotor 20, the coil 24, etc., and discharges formed in the housing 18. The gas is discharged from the outlets 18a and 18b to the branch passages 50c and 50d. The oil in the branch passages 50 c and 50 d joins again in the oil passage 50 and is cooled again in the heat exchanger 38. Since the oil is cooled in front of the oil pump 54, the heat damage of the oil pump 54 can be prevented and the load can be reduced.

  Although not shown, the system of FIG. 1 has a control device. The control device is electrically connected to various sensors including the temperature sensor 52 described above, various actuators including the switching valve 42, and the like. The control device is mainly composed of a computer including a CPU, a ROM, and a RAM. Various control routines are stored in the ROM. In the present embodiment, the control device performs control to shut off the flow of the cooling water to the heat exchanger 38 by operating the switching valve 42 based on the signal from each sensor.

  Specifically, the control device detects the oil temperature downstream of the heat exchanger 38 based on the output from the temperature sensor 52. When the detected oil temperature is lower than a predetermined reference temperature, the control device closes the switching valve 42. Thereby, the inflow of the cooling water to the heat exchanger 38 is blocked, and all the cooling water flows through the bypass passage 40 side. Therefore, heat exchange between the oil and the cooling water in the heat exchanger 38 is stopped. This prevents overcooling of the oil when the oil temperature is low. Therefore, the loss of the bearings 14 and 16 of the electric supercharger 10 can be reduced and the efficiency of the electric supercharger 10 can be prevented from being lowered.

  In the present embodiment, the coolant passage 32 is a separate coolant passage from the engine coolant circuit. When the bearing is cooled by a part of the engine cooling water, high-temperature cooling water is introduced into the cooling water passage 26 on the contrary, and the motor may be damaged. Therefore, in order to avoid such a situation, the cooling water passage 32 is separated from the engine cooling water circuit.

Embodiment 2. FIG.
FIG. 4 is a schematic diagram for explaining the system configuration of the second embodiment. In the system of FIG. 4, the oil passage 70 forms a part of the oil supply circuit of the engine, except that the installation positions of the heat exchanger 38 and the temperature sensor 52 in the oil passage 70 are different. It has the same configuration as the system.

  Specifically, the heat exchanger 38 is installed in the vicinity of the oil supply ports 28 a and 30 a of the housing 18 of the electric supercharger 10. That is, in the oil passage 70, the heat exchanger 38 is installed on the downstream side of the oil pump 54. The configuration of the heat exchanger 38 is the same as that in FIGS. 2 and 3, and the oil passage 62 of the heat exchanger 38 is a passage constituting a part of the oil passage 70.

  In the present embodiment, the oil passage 70 constitutes a part of the engine oil circuit, and the oil is also used for lubricating the engine side member. The oil that has lubricated the engine-side member flows into the heat exchanger 38 from the oil passage 70. In the heat exchanger 38, the oil is cooled once and then introduced into the oil passages 28 and 30 of the electric supercharger 10 without being introduced into other members on the engine side.

  The cooling water passage 32 is a water channel of a different system from the engine cooling water circuit, as in the first embodiment. The arrangement configuration on the cooling water passage 32 side is the same as that in FIG. That is, a heat exchanger 38 is installed downstream of the water pump 36, a bypass passage 40 that bypasses the heat exchanger 38 is connected to the cooling water passage 32, and a portion of the cooling water passage 32 that is bypassed by the bypass passage 40. The switching valve 42 is installed.

  In the second embodiment, the control device detects the oil temperature based on the output of the temperature sensor 52 installed immediately downstream of the heat exchanger 38 in the oil passage, and the detected oil temperature is a predetermined reference temperature. When the temperature is lower, the switching valve 42 is closed and the flow of the cooling water into the heat exchanger 38 is stopped once. This prevents overcooling of the oil.

  With the above configuration, according to the second embodiment, since the oil is cooled immediately before being introduced into the electric supercharger 10, each component in the electric supercharger 10 can be effectively cooled.

  In the above embodiment, when referring to the number of each element, quantity, quantity, range, etc., the reference is made unless otherwise specified or the number is clearly specified in principle. The invention is not limited to the numbers. Further, the structure and the like described in this embodiment are not necessarily essential to the present invention unless otherwise specified or clearly specified in principle.

DESCRIPTION OF SYMBOLS 8 Compressor wheel 10 Electric supercharger 12 Rotating shaft 14, 16 Bearing 18 Housing 18a, 18b Exhaust port 20 Rotor 22 Stator core 24 Coil 26 Cooling water passage 28, 30 Oil passage 28a, 30 Supply port 32 Cooling water passage 32a Branch part 32b Junction section 34 Sub-radiator 36 Water pump 38 Heat exchanger 40 Bypass path 42 Switching valve 50 Oil path 50a, 50b, 50c, 50d Branch path 52 Temperature sensor 54 Oil pump 60 Cooling water path 62 Oil path 64 Partition section 66 Cooling fin 70 Oil passage

Claims (1)

A bearing formed in the housing of the electric supercharger and supporting the rotating shaft of the electric supercharger;
An oil passage communicating with the bearing and circulating oil for oil-lubricating the bearing;
A cooling water circuit configured to be separated from the cooling water circuit of the internal combustion engine, and circulating the cooling water in the housing;
A heat exchanger installed outside the housing, wherein the oil passage and the cooling water passage are connected together to exchange heat between the oil in the oil passage and the cooling water in the cooling water passage;
One end is connected to a branch portion upstream of the heat exchanger in the cooling water passage, and the other end is connected to a confluence portion on the downstream side of the heat exchanger in the cooling water passage. A bypass passage to bypass the
A switching valve that is installed between the branch portion and the merging portion of the cooling water passage and opens and closes the cooling water passage;
When the temperature of the oil is lower than a reference temperature, a control device that operates the switching valve to block the cooling water from flowing into the heat exchanger;
A cooling device for an electric supercharger.

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