JP2008116018A - Power transmission device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To efficiently cool the inside of a power transmission device by a simple structure in the power transmission device mounted to a vehicle and sending out the motive power of a prime mover toward a driving wheel. <P>SOLUTION: This power transmission device 18 has a gear train 28, a case 50 storing the gear train, a cooling part 64 cooling the inside of the case 50, and a cooling jacket 52 cooling the cooling part, and also has a guiding passage 62 guiding lubricating oil scraped up by the rotational operation of the gear train 28 to the cooling part 64, and cools the lubricating oil guided by this guiding passage 62 by contacting with the cooling part 64. The cooled lubricating oil is supplied to a heating element in of the case 50, and cools the heating element. Thus, the inside of the power transmission device 18 can be efficiently cooled by arranging the simple structure such as the guiding passage 62. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a power transmission device that is mounted on a vehicle and sends power of a prime mover toward drive wheels, and more particularly to a cooling structure thereof.

  A power transmission device is known as a device that is mounted on a vehicle and sends the power of a prime mover to drive wheels. This power transmission device is configured by housing a gear train for transmitting power and lubricating oil for lubricating the operation thereof in a case. When the gear train rotates, the heat generated from the gear train raises the temperature inside the case. In order to prevent this temperature rise, a technique is known in which a water-cooling type cooling jacket is arranged on the side surface outside the case. The cooling jacket removes heat mainly from the air through the case, thereby cooling the inside of the case.

  In addition, there are examples in which a motor as a prime mover is housed in a case in a hybrid vehicle or an electric vehicle that travels by the output of the motor. When the electric motor rotates, the heat generated from the electric motor is added to the heat from the gear train, which further increases the temperature inside the case.

  In order to prevent this temperature increase, Patent Document 1 below discloses a power transmission device that cools the lubricating oil and cools the electric motor with this lubricating oil. This power transmission device is provided with a heat exchanger outside the case and a pump for sending lubricating oil to the heat exchanger. By the operation of the pump, the lubricating oil sent from the inside of the case to the heat exchanger is cooled by the heat exchanger and returned to the inside of the case. When the returned lubricating oil is directly supplied to the motor that has generated heat, the motor can be cooled. Further, the lubricating oil can cool the air and the gear train inside the case, and can cool the entire inside of the case.

JP 2005-117790 A JP 2004-180477 A

  In the power transmission device provided with a cooling jacket on the outside of the case, the inside of the case is cooled mainly using air as a medium. However, since the heat transfer coefficient of air is poor, it cannot be cooled efficiently.

  On the other hand, the power transmission device disclosed in Patent Document 1 cools the inside of the case and the electric motor using a lubricating oil having a heat transfer coefficient better than that of air as a medium. Since this power transmission device has a heat exchanger and a pump outside the case, the installation space becomes large. However, the installation space in the vehicle is limited, and there is no room for the installation space of the power transmission device.

  The objective of this invention is providing the power transmission device which can cool the inside of a power transmission device efficiently with a simple structure.

  The present invention is a power transmission device that is mounted on a vehicle and sends power of a prime mover toward a drive wheel, and is provided in a gear train that transmits power, a case that houses the gear train, and the case, A cooling unit that cools the inside of the case, and a lubricating oil that is stored so that a part of the gear train is immersed in the bottom of the case and is scooped up by the rotation operation of the gear train is received and guided to the cooling unit. And a lubricating oil guided by the guiding path is in contact with the cooling portion to be cooled.

  A cooling jacket for cooling the cooling unit, the cooling unit being provided in contact with an outer surface of the case, wherein the cooling jacket corresponds to a back side of a portion of the outer surface in contact with the case; It may be a part of the inner surface.

  The cooling jacket may be provided on a side surface of the case.

  Furthermore, an electric motor as a prime mover is accommodated in the case, and the electric motor can be cooled by lubricating oil.

  According to the power transmission device of the present invention, the inside of the power transmission device can be efficiently cooled with a simple structure.

  Hereinafter, embodiments of a power transmission device according to the present invention will be described with reference to the drawings. As an example, a hybrid vehicle that travels by the output of an internal combustion engine and an electric motor will be described, and a power transmission device mounted thereon will be described.

  First, a power transmission system of the hybrid vehicle 10 to which the power transmission device 18 of the present embodiment is applied will be described with reference to FIG. FIG. 1 is a diagram illustrating a schematic configuration of a hybrid vehicle 10 according to the present embodiment. The hybrid vehicle 10 includes an internal combustion engine 12 (hereinafter referred to as an engine 12), a first motor generator 14 (hereinafter referred to as a first MG 14), and a second motor generator 16 (hereinafter referred to as a second MG 16) as prime movers. In addition, a power transmission device 18 is mounted as a device for sending the power of these prime movers 12, 14, 16 toward the drive wheels 42.

  The power transmission device 18 includes a power distribution and integration mechanism 20 including a planetary gear mechanism that distributes and integrates the power of the engine 12 and the first and second MGs 14 and 16, a gear train 28 that transmits power by a plurality of gears, and the like. A case 50 for housing the container. The power distribution and integration mechanism 20 is constituted by a planetary gear mechanism, and the engine 12 and the first and second MGs 14 and 16 are connected to the three elements of the planetary gear mechanism. That is, the engine 12 is connected to the planetary gear 24 of the planetary gear mechanism through the damper 44, the first MG 14 is connected to the sun gear 22 of the planetary gear mechanism, and the second MG 16 is connected to the ring gear 26 of the planetary gear mechanism. Further, a gear train 28 is connected to the ring gear 26, and drive wheels 42 are connected to the gear train 28 via an axle 40.

  The gear train 28 includes a counter drive gear 30 connected to the ring gear 26 of the planetary gear mechanism, a counter driven gear 32 that meshes with the counter drive gear 30, a final drive gear 34 that is coupled to the counter driven gear 32, and a final that meshes with the counter drive gear 32. A driven gear 36 and a differential mechanism 38 connected to the final driven gear 36 are provided. Drive wheels 42 are connected to the differential mechanism 38 via an axle 40. The differential mechanism 38 absorbs the rotational difference between the left and right drive wheels 42.

  With such a configuration of the gear train 26, the power of the prime movers 12, 14, and 16 integrated by the power distribution and integration mechanism 20 causes the counter drive gear 30, the counter driven gear 32, the final drive gear 34, and the final driven gear 36. Thus, the speed is changed and transmitted to the differential mechanism 38, and the power distributed to the left and right by the differential mechanism 38 is transmitted to the driving wheel 42 via the axle 40.

  By configuring the power transmission system of the hybrid vehicle 10 as described above, the power of each of the prime movers 12, 14, and 16 is transmitted to the drive wheels 42 via the power transmission device 18 and the axle 40, and the hybrid vehicle 10 Can travel.

  The hybrid vehicle 10 can travel in various modes by controlling the output of the engine 12 and the first and second MGs 14 and 16 according to the traveling state. This mode is, for example, a mode in which the engine 12 or the second MG 16 travels, a mode in which the engine 12 and the second MG 16 travel in cooperation, and a part of the output of the engine 12 generates power in the first MG 14. The mode to perform. Furthermore, a mode that allows regenerative power generation by second MG 16 by the kinetic energy of hybrid vehicle 10 input from drive wheels 42 during deceleration is also included.

  The first and second MGs 14 and 16 are housed in the case 50 in the same manner as the power distribution and integration mechanism 20 and the gear train 28. In the case 50, when the first and second 14, 16, the power distribution and integration mechanism 20 and the gear train 28 rotate, the heat generated from these mechanisms raises the temperature inside the case 50. In order to prevent this temperature rise, a cooling system for cooling the inside of the case 50 will be described below with reference to FIGS. FIG. 2 is a side view showing the engine room 54 of the hybrid vehicle 10 according to the present embodiment. In addition, the left side of this figure shows the front of the hybrid vehicle 10, that is, the traveling direction of the vehicle.

  The engine room 54 includes a power transmission device 18, first and second MGs 14 and 16 (not shown) housed in the case 50, and between these MGs 14 and 16 and a secondary battery (not shown). An inverter 58 for converting the power of the inverter is mounted. A power transmission device 18 coupled to the axle 40 is disposed at the lowermost portion of the engine room 54, and an inverter 58 is disposed above the power transmission device 18. The engine 12 is not shown because it is disposed in the back of the power transmission device 18.

  In the engine room 54, the first MG 14 and the second MG 14 16 inside the case 50, and the power between them and a battery (not shown) are converted to the traveling direction side from the power transmission device 18 and the inverter 58. A hybrid cooling system 66 for cooling the inverter device 58 is mounted. The hybrid cooling system 66 has a circulation path 68 through which cooling water circulates. A cooling jacket 52, a radiator 56, an inverter 58, and a pump 60 are provided in this circulation path 68 in this order.

  The cooling jacket 52 is provided in contact with the outer side surface of the case 50, and cools the inside of the case 50 via the case 50. The radiator 56 is a device that cools cooling water by exchanging heat with the outside air. A radiator fan 56 a attached to the radiator 56 forcibly sends outside air to the radiator 56. For example, the pump 60 changes the rotation speed based on the temperature of the cooling water and sends out the cooling water.

  By the operation of the pump 60, for example, cooling water from the radiator 56 is sent to the inverter 58. The cooling water sent to the inverter 58 is heated by removing the heat inside the inverter 58. Then, the cooling water is sent to the cooling jacket 52, further heated by removing the heat inside the power transmission device 18, and sent to the radiator 56. The cooling water sent to the radiator 56 is cooled by heat exchange with the outside air, and is sent again to the inverter 58 and the cooling jacket 52. As described above, the cooling water circulating through the circulation path 68 removes the heat inside the power transmission device 18, whereby the inside of the power transmission device 18, that is, the inside of the case 50 can be cooled.

  As will be described later, lubricating oil that lubricates the operation of the power distribution and integration mechanism 20 and the gear train 28 is stored inside the case 50, and this lubricant cools the power distribution and integration mechanism 20 and the gear train 28. . Further, the lubricating oil is directly supplied to the first and second MGs 14 and 16 that generate a larger amount of heat than the mechanisms 20 and 28, and also cools the first and second MGs 14 and 16. Thus, in the power transmission device 18, the entire interior of the case 50 is cooled using the lubricating oil as a cooling medium.

  Since the lubricating oil is stored in the bottom portion of the case 50, if the cooling jacket 52 is provided outside the bottom portion, the lubricating oil contacting the case 50 with the cooling jacket 52 can be positively cooled. However, as described above, the power transmission device 18 coupled to the axle 40 is disposed at the lowermost part of the engine room 54, and there is no space for providing the cooling jacket 52 on the bottom surface outside the case 50, which is further below. Thus, since the cooling jacket 52 cannot be provided on the bottom surface outside the case 50, the cooling jacket 52 is provided on the side surface or the top surface other than the bottom surface outside the case 50. The cooling jacket 52 provided on the outer side surface or the upper surface of the case 50 must cool mainly the air having a lower thermal conductivity than the lubricating oil, not the lubricating oil stored in the case 50. Cooling efficiency is low. However, the power transmission device 18 of the present embodiment solves this problem by adopting the structure described below.

  Next, the cooling structure of the power transmission device 18 will be described with reference to the drawings. FIG. 3 is a cross-sectional view illustrating a schematic configuration of the power transmission device 18 when viewed from AA in FIG. 1. As shown in FIG. 3, a cooling jacket 52 is provided on the outer side surface of the case 50 so as to be in contact therewith. The portion of the inner surface of the case 50 corresponding to the back side of the outer surface portion of the case 50 that is in contact with the cooling jacket 52 is the portion that is most cooled by the cooling jacket 52, and this portion is hereinafter referred to as a cooling portion 64. The cooling unit 64 cooled by the cooling jacket 52 can remove the heat inside the case 50 and cool the inside of the case 50.

  Inside the case 50, the first MG 14 is disposed substantially at the center, the counter driven gear 32 is disposed obliquely above and to the right of the first MG 14, and the final driven gear 36 is disposed below the counter driven gear 32. Lubricating oil is stored at the bottom of the case 50 so that the first MG 14 and a part of the final driven gear 36 are immersed therein. The accumulated lubricating oil is scraped up by the final driven gear 36 rotating.

  In addition, inside the case 50, a guide path 62 is provided that receives the scraped lubricating oil and guides it to the cooling unit 64. The guide path 62 has a receiving portion 62a that receives the lubricating oil scraped up at the end thereof. A flow path is formed from the receiving portion 62 a toward the bottom of the case 50 via the cooling portion 64. As a result, the scraped lubricating oil is guided by the guide path 62 along the direction of the arrow as shown in the figure. That is, the scooped up lubricating oil is received by the receiving portion 62 a, and the received lubricating oil is guided to the cooling portion 64 by the guide path 62. The induced lubricating oil is cooled in contact with the cooling unit 64 and returned to the bottom of the case 50.

  Next, the operation | movement which cools the power transmission device 18 is demonstrated. First, the power of the prime movers 12, 14, 16 is transmitted to the gear train 28 via the power distribution and integration mechanism 20. The gear train 28 is rotated by the transmitted power. As the final driven gear 36 included in the gear train 28 rotates, the lubricating oil accumulated at the bottom of the case 50 is scraped up. The scavenged lubricating oil scatters inside the case 50 toward the first and second MGs 14 and 16, the gear train 28, and the power distribution and integration mechanism 20 to lubricate each operation and generate heat from them. Remove. Further, a part of the lubricating oil that has been scraped up is received by the receiving portion 62 a, and the received lubricating oil is guided to the cooling portion 64 by the guide path 62. The induced lubricating oil contacts the cooling unit 64. Since the cooling unit 64 is cooled by the cooling jacket 52, the lubricating oil can be cooled. The cooled lubricating oil is returned to the bottom of the case 50.

  Next, another embodiment of the power transmission device 18 will be described with reference to the drawings. FIG. 4 is a cross-sectional view illustrating a schematic configuration of another power transmission device 18 when viewed from AA in FIG. 1. As shown in FIG. 4, the power transmission system inside the case 50 according to the present embodiment is the same as that of the above-described embodiment, and thus detailed description of these power transmission systems is omitted.

  In the power transmission device 18, a cooling jacket 52 is provided inside the case 50. The cooling jacket 52 is disposed with a gap between the first MG 14 and the side surface inside the case 50. The surface of the cooling jacket 52 corresponds to the cooling unit 64 that cools the inside of the case 50. Therefore, the guide path 62 is provided so as to guide the lubricating oil to the cooling portion 64 of the cooling jacket 52.

  The guide path 62 has a receiving portion 62a that receives the lubricating oil that has been scraped up above the first MG 14, and is formed so as to be connected to the surface above the cooling jacket 52 from the receiving portion 62a. Has been. Since the cooling jacket 52 is arranged at a distance from the inner side surface of the case 50, the lubricating oil is guided to the gap. As a result, the lubricating oil that has been scraped up is received by the receiving portion 62 a and guided to the cooling jacket 52 by the guide path 62. Lubricating oil from the guide path 62 flows while contacting the surface of the cooling jacket 52 facing the side surface inside the case 50, that is, the cooling portion 64. Since the cooling unit 64 is cooled by the cooling jacket 52, the lubricating oil can be cooled. The cooled lubricating oil is returned to the bottom of the case 50.

  According to the power transmission device 18 according to each of the embodiments described above, by providing the guide path 62 having a simple structure, the lubricating oil as a cooling medium is guided to the cooling unit 64, and the induced lubricating oil is supplied to the cooling unit. 64 can be cooled. By supplying the cooled lubricating oil to the devices and mechanisms that generate heat, it is possible to cool them and cool the entire interior of the case 50 efficiently. In addition, due to the rotational operation of the final driven gear 36, the scraped lubricating oil is supplied to the guide path 62, and the oil level of the lubricating oil stored on the bottom surface of the case 50 is lowered by the amount of the supplied lubricating oil. The agitation resistance of the lubricating oil by the gear 36 can be reduced.

  According to the power transmission device 18 according to another embodiment, the lubricating oil can be cooled by providing the cooling jacket 52 inside the case 50, and at the surface of the cooling jacket 52 where the lubricating oil is not induced. Can mainly cool the air. The entire inside of the case 50 can be cooled more efficiently by the cooled lubricating oil and air.

  In the embodiment described with reference to FIG. 3 described above, the case where the portion provided so that the cooling jacket 52 contacts the outside of the case 50 is the side surface of the case 50 has been described. However, the present invention is not limited to this configuration. The cooling jacket 52 may be provided on the upper surface outside the case 50. When the cooling jacket 52 is provided on the upper surface outside the case 50, air having a heat transfer coefficient lower than that of the lubricating oil must be mainly cooled as in the case where the cooling jacket 52 is provided on the side surface of the case outer side 50. In order to solve this problem, if a guide path 62 for guiding the lubricating oil is provided in the inner surface portion of the case 50 corresponding to the back side of the portion where the cooling jacket 52 is in contact with the outer surface of the case 50, that is, the cooling portion 64, Lubricating oil can be cooled.

  In the embodiment described above with reference to FIG. 3, the cooling unit 64 is cooled by the cooling jacket 52 of the hybrid cooling system 66, but is not limited to this configuration. Air-cooling fins attached to the outer surface of the case 50 may be used.

  In each of the above embodiments, the case where the power transmission device 18 is mounted on the hybrid vehicle 10 has been described. However, the present invention is not limited to this configuration. Any vehicle may be used as long as it is equipped with a power transmission device that includes lubricating oil that cools a mechanism that transmits power, such as the gear train 28.

It is a figure showing the schematic structure of the hybrid vehicle concerning this embodiment. It is a side view which shows the engine room of the hybrid vehicle which concerns on this embodiment. It is sectional drawing which shows schematic structure of the power transmission device when it sees from AA in FIG. It is sectional drawing which shows schematic structure of another power transmission device of FIG.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 Hybrid vehicle, 12 Engine, 14 1st MG, 16 2nd MG, 18 Power transmission device, 20 Power distribution integrated mechanism, 22 Sun gear, 24 Planetary gear, 26 Ring gear, 28 Gear train, 30 Counter drive gear, 32 Counter Driven Gear, 34 Final Drive Gear, 36 Final Drive Gear, 38 Differential Mechanism, 40 Axle, 42 Drive Wheel, 44 Damper, 50 Case, 52 Cooling Jacket, 54 Engine Room, 56 Radiator, 58 Inverter, 60 Pump, 62 Induction Path, 64 cooling section, 66 hybrid cooling system, 68 circulation path.

Claims (4)

A power transmission device that is mounted on a vehicle and sends the power of a prime mover toward a drive wheel,
A gear train for transmitting power;
A case for housing the gear train;
A cooling unit provided in the case for cooling the inside of the case;
A guide path that receives and guides the lubricating oil, which is stored so that a part of the gear train is immersed in the bottom of the case, and is scraped up by the rotational motion of the gear train, to the cooling unit;
Have
The lubricating oil guided by the guide path is cooled in contact with the cooling unit,
A power transmission device characterized by that. The power transmission device according to claim 1,
A cooling jacket that is provided in contact with the outer surface of the case and cools the cooling unit;
The cooling section is a portion of the inner surface of the case corresponding to the back side of the outer surface portion where the cooling jacket is in contact with the case.
A power transmission device characterized by that. The power transmission device according to claim 2,
The cooling jacket is provided on a side surface of the case,
A power transmission device characterized by that. The power transmission device according to any one of claims 1 to 3,
In the case, an electric motor as a prime mover is accommodated, and the electric motor is cooled by lubricating oil.
A power transmission device characterized by that.

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