JP2011250524A - Cooling device of power transmission device for vehicle - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cooling device of a power transmission device for a vehicle that is capable of suppressing reduction in transmission efficiency while ensuring cooling performance for an electric motors etc.SOLUTION: When an oil temperature in a motor chamber 84 rises and reaches a specified temperature of α, an on-off valve 104 is opened to communicate a first opening hole 100. When the oil temperature in the motor chamber 84 does not reach the specified temperature of α, the on-off valve 104 is closed to block the first opening hole 100. The on-off valve 104 constituted as above allows efficient cooling of an electric motor 22 through oil circulation when the electric motor 22 requires cooling. When no cooling of the electric motor 22 is required, by accumulating the oil in the motor chamber 84 and reducing oil surface height in a gear chamber 90, agitation resistance of a ring gear 42 can be suppressed and thereby reduction in transmission efficiency can be suppressed.

Description

  The present invention relates to a cooling device for a vehicle power transmission device equipped with an electric motor, and more particularly to a technique for suppressing a reduction in fuel consumption due to oil agitation while ensuring cooling performance of the electric motor or the like.

  2. Description of the Related Art Vehicles including a power transmission device that drives a vehicle by using a driving force of an electric motor, such as an electric vehicle and a hybrid vehicle, are known. In such a vehicle, since the motor generates heat when the motor in the power transmission device is driven, a plurality of structures for cooling the motor have been proposed. For example, the cooling device for an electric motor described in Patent Document 1 includes an oil pump 15 that rotates in synchronization with the electric motor M1, pumps up oil by the oil pump 15, and cools the electric motor with the oil. When the rotation speed is less than or equal to a predetermined rotation speed, a technique is disclosed in which the check valve 24 is closed to shut off the supply of oil to the electric motor. Further, in the vehicle electric motor described in Patent Document 2, the oil stored in the first oil chamber 154 is scraped up by the gear 150, and the pumped-up oil is supplied to the cooling oil supply port 118 so that the electric motor 148 is driven. A technique for cooling is disclosed (see FIGS. 15 and 16).

JP 2007-228669 A JP 2001-112210 A

  By the way, in the electric motor cooling device described in Patent Document 1, although the electric motor is efficiently cooled, it is necessary to drive the oil pump 15, and the driving torque of the oil pump 15 is consumed and torque transmission efficiency (transmission) is transmitted. Efficiency) will be reduced. In particular, at low temperatures, with the increase in oil viscosity, there is a possibility that the transmission efficiency is remarkably lowered and the fuel efficiency is deteriorated. Further, the provision of the oil pump 15 necessitates a pressure regulating valve, which complicates the structure and increases the weight. On the other hand, in the vehicle electric motor of Patent Document 2, since the oil is supplied by scooping up the gear that rotates in the oil bath, the structure is simplified as long as the oil pump is not provided, and transmission by the driving torque of the oil pump is performed. There is no reduction in efficiency. However, when the oil is raked up by the gear, the height of the oil surface is always substantially constant regardless of the oil temperature. For example, when the oil is low in temperature, the stirring resistance when the gear rakes up the oil is large. Therefore, there is a possibility that the transmission efficiency is lowered and the fuel consumption is lowered.

  The present invention has been made against the background of the above circumstances, and the object of the present invention is to reduce the transmission efficiency while ensuring the cooling performance of the electric motor or the like in the vehicle power transmission device equipped with the electric motor. An object of the present invention is to provide a cooling device for a vehicle power transmission device that can be suppressed.

  In order to achieve the above object, the gist of the invention according to claim 1 is that: (a) a cooling device for a vehicle power transmission device including an electric motor in a case; (b) the electric motor; A motor chamber formed so that oil is stored in the vertical lower portion and (c) the motor chamber is formed adjacent to the motor chamber with a partition wall therebetween, and accommodates a gear that rotates when the vehicle travels, and the vertical lower portion A gear chamber formed so that oil is stored in a state where a part of the gear is immersed in the motor, and (d) the oil in the gear chamber swung up by the rotation of the gear. A cooling oil passage that leads to the motor chamber; and (e) an opening that is formed vertically below the preset minimum oil level of the gear chamber of the partition wall and that communicates the motor chamber and the gear chamber. A hole, (f) provided in the opening hole, When the oil temperature in the motor chamber reaches a predetermined temperature, and flow rate switching mechanism for switching to a predetermined flow rate which is previously set the flow rate of the oil flowing through the opening hole, characterized in that it comprises.

  The gist of the invention according to claim 2 is that, in the cooling device for a vehicle power transmission device according to claim 1, the flow rate switching mechanism is configured such that when the oil temperature in the motor chamber reaches a predetermined temperature. It is an on-off valve that is opened.

  The gist of the invention according to claim 3 is that, in the cooling device for a vehicle power transmission device according to claim 1, the flow rate switching mechanism is configured such that when the oil temperature in the motor chamber reaches a predetermined temperature. A throttle that adjusts the oil flowing through the opening hole to a predetermined flow rate set in advance.

  According to a fourth aspect of the present invention, there is provided a cooling device for a vehicle power transmission device according to any one of the first to third aspects, wherein the partition wall has a predetermined value higher than a lowermost rotor surface of the electric motor. A second opening hole is formed so as to be formed vertically below and always communicate with the motor chamber and the gear chamber.

  According to a fifth aspect of the present invention, there is provided the vehicle power transmission device cooling device according to any one of the first to fourth aspects, wherein the oil that has been scraped up by the gear is provided in the cooling oil passage. A catch tank is provided for temporarily storing.

  According to a sixth aspect of the present invention, there is provided a cooling device for a vehicle power transmission device according to any one of the first to fifth aspects, wherein the electric motor has a predetermined vehicle speed at which a vehicle speed is preset. It is driven in the following range.

  According to a seventh aspect of the present invention, there is provided the cooling device for a vehicle power transmission device according to the second aspect, wherein the on-off valve has a tapered surface formed in the opening hole and a tapered surface thereof. When the ball that closes the opening hole by being pressed and the oil temperature reaches a predetermined temperature, the ball is pressed against the tapered surface to close the opening hole, and when the oil temperature reaches the predetermined temperature, A spring made of a shape memory alloy that causes the ball to move freely by shortening the overall length and communicates the opening hole, and a spring receiving member that is provided in the opening hole and receives the reaction force when the spring presses the ball It is characterized by including these.

  According to the cooling device for a vehicle power transmission device of the first aspect of the present invention, for example, when the motor is energized and driven, the oil temperature of the oil in the motor chamber rises and reaches a predetermined temperature due to heat generated at that time. The flow rate flowing through the opening hole is a predetermined flow rate set in advance. In such a case, the oil in the gear chamber is led to the motor chamber through the cooling oil passage, and is circulated back to the gear chamber through the opening hole, whereby the oil temperature in the motor chamber is lowered and the electric motor is cooled. . On the other hand, when the oil temperature in the motor chamber does not reach the predetermined temperature, specifically, when the motor is rotated from the wheel without being energized, the oil temperature in the motor chamber is low and flows from the motor chamber into the gear chamber. When the flow rate to be reduced is reduced by the flow rate switching mechanism, the oil stored in the motor chamber increases and the oil stored in the gear chamber decreases. Thereby, the height of the oil level stored in the gear chamber is reduced, and the stirring resistance when the gear stirs the oil is reduced. From the above, by providing a flow rate switching mechanism, the motor is cooled by circulating oil when the motor needs to be cooled (during operation), and when the motor does not need to be cooled (during non-operation), the motor chamber By storing oil in the gear chamber and lowering the height of the oil level in the gear chamber, it is possible to suppress the gear agitation resistance and suppress the decrease in transmission efficiency. However, when the motor is cooled, the oil level in the gear chamber increases, but since the oil temperature including the gear chamber has increased at this time, the viscosity of the oil has already decreased, and the decrease in efficiency is minimized. It is done.

  According to the cooling device for a vehicle power transmission device of the invention according to claim 2, the flow rate switching mechanism is an on-off valve that is opened when the oil temperature of the motor chamber reaches a predetermined temperature. Therefore, in a state where the oil temperature in the motor chamber does not reach a predetermined temperature (low oil temperature), the on-off valve is closed and the communication between the motor chamber and the gear chamber is shut off, so the oil stored in the motor chamber On the other hand, the oil in the gear chamber decreases and the oil level decreases. Therefore, a decrease in transmission efficiency is suppressed as the stirring resistance when the gear stirs high viscosity oil is reduced. When the oil temperature in the motor chamber reaches a predetermined temperature (high oil temperature), the on-off valve is opened and the motor chamber communicates with the gear chamber, so that the oil in the gear chamber passes through the cooling oil passage. The oil flows into the motor chamber and is recirculated to the gear chamber. As a result, the oil is actively circulated, so that the oil temperature in the motor chamber is lowered and the motor is cooled. From the above, in a low oil temperature state where the cooling of the motor is not necessary, the oil is stored in the motor chamber, so that a decrease in transmission efficiency is suppressed. By circulating, the electric motor can be efficiently cooled.

  According to the cooling device for a vehicle power transmission device of a third aspect of the present invention, the flow rate switching mechanism causes the oil flowing through the opening hole when the oil temperature in the motor chamber reaches a predetermined temperature. Since the throttle is adjusted to a preset predetermined flow rate, when the oil temperature of the motor chamber does not reach the predetermined temperature, the amount of oil flowing into the gear chamber does not reach the preset predetermined flow rate, and the gear As the oil flowing into the chamber is reduced, the height of the oil level in the gear chamber decreases. Therefore, a reduction in transmission efficiency is suppressed as the stirring resistance when the gear stirs the oil is reduced. When the oil temperature in the motor chamber reaches a predetermined temperature, the oil in the gear chamber passes through the cooling oil passage, and the oil circulating from the opening hole to the gear chamber via the motor and the motor chamber increases. Oil is actively circulated to cool the motor. From the above, in a low oil temperature state where the cooling of the electric motor is not required, the oil stored in the motor chamber is increased, the oil in the gear chamber is decreased, and the stirring resistance is reduced, so that a decrease in transmission efficiency is suppressed. When reaching a high oil temperature state where the motor needs to be cooled, the oil is actively circulated so that the motor can be efficiently cooled.

  According to a cooling device for a vehicle power transmission device of a fourth aspect of the present invention, the partition wall is formed vertically below the rotor lowermost surface of the electric motor by a predetermined value, and the motor chamber and the gear chamber. Since the second opening hole that always communicates with each other is formed, the oil level of the motor chamber does not exceed the lowermost surface of the rotor even at the highest position. Therefore, even when the rotor of the electric motor rotates in operation or non-operation, the oil is prevented from being stirred by the rotor of the electric motor, so that loss due to the oil accompanying the rotor is prevented.

  According to the cooling device for a vehicle power transmission device of the invention according to claim 5, the cooling oil passage is provided with a catch tank for temporarily storing the oil scooped up by the gear. The oil scooped up by the gear is stored in the catch tank, so that the oil temperature in the gear chamber can be adjusted to an optimum height.

  According to the cooling device for a vehicle power transmission device of the invention according to claim 6, the electric motor is driven in a range where the vehicle speed of the vehicle is equal to or lower than a predetermined vehicle speed set in advance. The electric motor is driven and the oil temperature in the motor chamber rises. On the other hand, since the vehicle speed is less than or equal to the predetermined vehicle speed, the gear rotation speed is low and the oil temperature on the gear chamber side is low. At this time, when the oil temperature in the motor chamber reaches a predetermined temperature, the low temperature oil in the gear chamber is actively circulated through the motor chamber, so that the oil temperature in the motor chamber decreases and the motor is cooled. The Further, when the vehicle speed exceeds the predetermined vehicle speed, the electric motor is stopped. Therefore, when the oil temperature in the motor chamber decreases and becomes equal to or lower than the predetermined temperature, the flow of oil from the motor chamber to the gear chamber is suppressed by the flow rate switching mechanism. The At this time, as the oil stored in the motor chamber increases, the oil in the gear chamber decreases, the oil level becomes lower, and the agitation resistance is suppressed.

  According to the cooling device for a vehicle power transmission device of the invention of claim 7, the spring is made of a shape memory alloy, and the ball is pressed against the tapered surface until the oil temperature reaches a predetermined temperature. When the opening hole is closed and the oil temperature reaches a predetermined temperature, the overall length is shortened so that the ball moves freely and the opening hole is communicated, so that the oil surface height of the gear chamber can be suitably adjusted. In addition, an on-off valve that efficiently cools the electric motor can be configured.

It is a figure which shows schematic structure of the drive system of the vehicle to which this invention was applied. FIG. 2 is a cross-sectional view for explaining the structure of the rear transaxle in FIG. 1 in detail. FIG. 3 is a diagram illustrating an oil circulation path in the rear transaxle of FIG. 2. In the arrow view which looked at the motor case shown in FIG. 3 from the arrow X side, it is the figure which showed notionally the mechanism by which oil is stored by a catch tank. FIG. 5 is an enlarged view of the motor chamber in FIG. 2, and is a cross-sectional view cut along a cutting line Z indicated by a one-dot chain line in FIG. 4. It is sectional drawing of the motor chamber of the rear transaxle which is another Example of this invention, Comprising: It corresponds to FIG. It is a figure which shows the relationship between the oil temperature and the flow volume of the oil which flows through the inside of an orifice.

  Here, the cooling device for a vehicle power transmission device according to the present invention is preferably applicable as appropriate in a vehicle including an electric motor such as an electric vehicle or a hybrid vehicle.

  Preferably, the gear rotatably accommodated in the gear chamber is a ring gear of a differential mechanism. In this way, when the vehicle travels, as the ring gear rotates, the oil that contacts the ring gear is scraped and supplied to the cooling oil passage.

  Preferably, the predetermined oil temperature in the motor chamber is set in advance by experiments and calculations, and is set to the oil temperature when the motor set in advance in a rated manner reaches a temperature that requires cooling. The In this way, when the motor reaches a temperature that requires cooling, the motor oil temperature becomes a predetermined temperature, so that the oil flowing through the opening hole reaches a predetermined flow rate, and the oil is actively circulated. The motor is cooled. That is, when the electric motor reaches a temperature that requires cooling, the electric motor is cooled, and the cooling efficiency is improved.

  Preferably, the aperture diameter (opening area) of the diaphragm is set in advance by experiment or calculation, and when the oil temperature of the oil reaches a predetermined temperature based on the viscosity that changes according to the oil temperature. The predetermined flow rate set in advance in the throttle is set to flow.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the following embodiments, the drawings are appropriately simplified or modified, and the dimensional ratios, shapes, and the like of the respective parts are not necessarily drawn accurately.

  FIG. 1 is a diagram showing a schematic configuration of a vehicle drive system to which the present invention is applied. In FIG. 1, this vehicle includes an engine 12 configured by a known internal combustion engine such as a gasoline engine or a diesel engine that outputs power by burning fuel, and an electric motor 14. A front transaxle 20 that selectively outputs one or both powers to rotationally drive the pair of left and right front axles 16 and the front wheels 18 and an electric motor 22 are built in, and a pair of left and right rear axles ( (Axle) 24 and a rear transaxle 28 that rotationally drives a rear wheel 26.

  Such an electric four-wheel drive vehicle, for example, travels by the power of the motor 14 and the motor 22 when the vehicle starts, and travels by the power of the engine 12 in a travel region where the operating efficiency of the engine 12 is good. It has become. Further, when the engine 12 has poor operating efficiency, such as when traveling at a low speed or down a gentle slope, the operation of the engine 12 is stopped and the vehicle is driven by the power of the motor 14. Further, during acceleration traveling, the vehicle travels with the power of the engine 12, and the power of the electric motor 14 and the electric motor 22 is supplementarily used. Further, at the time of deceleration (including when the accelerator is off), the motor 14 and the motor 22 are operated as a generator to convert kinetic energy into electric energy and collect it. Further, the stability of the vehicle is ensured by operating the electric motor 22 in a four-wheel drive state according to the traveling state of the vehicle and suitably controlling the torque distribution of the front and rear wheels. For example, when accelerating or turning on a low friction road, the torque distribution of the front and rear wheels is optimized, and the stability of the vehicle is ensured.

  FIG. 2 is a cross-sectional view for explaining in detail the structure of a rear transaxle 28 (corresponding to the vehicle power transmission device of the present invention) to which the present invention is applied. As shown in FIG. 2, the rear transaxle 28 includes an electric motor 22 that functions as a drive source of the rear transaxle 28 in an axle case 30 (corresponding to the case of the present invention) that is a non-rotating member, and the electric motor 22. By spline fitting, the motor 22 is rotated integrally with the motor 22, and the drive shaft 32 having the counter drive gear 34 that meshes with the counter driven gear 38 of the counter shaft 36, which will be described later, the counter driven gear 38, and the counter driven gear 38 The counter shaft 36 includes a small-diameter drive pinion gear 40 and a known differential mechanism 46 configured to include a large-diameter ring gear 42 that meshes with the drive pinion gear 40.

  The axle case 30 includes an axle cover 30a, a motor case 30b, and a motor cover 30c, and is configured as one case by being fastened by bolts. The electric motor 22 is disposed on the inner peripheral side of the stator 50, a return stator 50 fixed to the motor case 30b by a bolt 48 so as not to rotate, a stator coil 51 wound around the stator 50, and the stator 50. The rotor 52 is a returnable rotor 52, and is connected to the inner peripheral end of the rotor 52. Both ends in the axial direction are supported by the axle case 30 via bearings 54 and 56 so as to be rotatable around the axis C1. And the rotor shaft 58.

  The drive shaft 32 having a cylindrical shape is rotatably supported by the axle case 30 via bearings 60 and 62 disposed at both end portions in the axial direction, and the outer peripheral surface end portion on the motor 22 side in the axial direction. Is spline-fitted to the rotor shaft 58 of the electric motor 22 so as to be rotated integrally with the rotor shaft 58. Further, a counter drive gear 34 is formed on the bearing 62 side in the axial direction of the drive shaft 32.

  The countershaft 36 is formed in a cylindrical shape and is supported by the axle case 30 so as to be rotatable around the axis C2 via bearings 64 and 66 disposed at both ends in the axial direction. Further, on the bearing 66 side in the axial direction of the counter shaft 36, a counter driven gear 38 having a larger diameter than the counter drive gear 34 that meshes with the counter drive gear 34 of the drive shaft 32, and a counter driven gear 38 that meshes with the ring gear 42 of the differential mechanism 46. A small-diameter drive pinion gear 40 is also formed.

  The differential mechanism 46 is a known differential gear device that generates a differential action on the left and right rear axles 24, and the countershaft 36 is connected to the large-diameter ring gear 42 connected to the differential case 68 of the differential mechanism 46 by a bolt 70. A drive pinion gear 40 is engaged. Therefore, when the counter shaft 36 rotates, the ring gear 42 and the differential case 68 are rotated around the axis C3. Then, in the differential mechanism 46, the rotation is transmitted to the left and right drive shafts 72 while causing a difference in rotational speed according to the traveling state of the turning vehicle. Note that the detailed mechanism of the differential mechanism 46 is the same as that of a known technique, and thus the description thereof is omitted.

  In the rear transaxle 28 configured as described above, when the electric motor 22 rotates, the rotation is decelerated via the counter shaft 36 and the differential mechanism 46 and transmitted to the left and right rear wheels 26.

  Next, the cooling device 101 that cools the electric motor 22 and the like provided in the transaxle 28 will be described. FIG. 3 shows an oil circulation path in the transaxle 28 of FIG. In the transaxle 28, a motor chamber 84 that houses the electric motor 22 is formed by fastening the motor case 30 b and the motor cover 30 c of the axle case 30 with bolts 80. In addition, the axle cover 30a and the motor case 30b are fastened to each other by bolts 86, 88 and the like, thereby forming a gear chamber 90 that accommodates the drive shaft 32, the counter shaft 36, the differential mechanism 46, and the like. The motor chamber 84 and the gear chamber 90 are disposed adjacent to each other with a partition wall 92 formed in the motor case 30b. The motor chamber 84 and the gear chamber 90 communicate with each other through opening holes (first opening hole 100 and second opening hole 102) described later. The motor chamber 84 and the gear chamber 90 have oil receiving structures that can store oil, and the oil that lubricates the electric motor 22 and the bearings is stored in the motor chamber 84 or the gear chamber 90. It becomes.

  In the transaxle 28, the vertically lower side of the ring gear 42 of the differential mechanism 46 is immersed in the oil stored in a part of the gear chamber 90. When the ring gear 42 rotates, the oil in the gear chamber 90 moves upward accordingly. The oil thus scooped up is temporarily stored in a catch tank 94 formed by fastening the axle cover 30a and the motor case 30b with bolts 86 and 86.

  The state in which the oil scraped up by the ring gear 42 is guided to the catch tank 94 will be described with reference to FIG. FIG. 4 is a diagram conceptually showing a mechanism in which oil is stored in the catch tank 94 when the motor case 30b of the axle case 30 is viewed from the arrow X side shown in FIG. Here, in FIG. 4, the shaft centers C1 to C3 correspond to the shaft center C1 of the electric motor 22, the shaft center C2 of the counter shaft 36, and the shaft center C3 of the ring gear 42 (differential mechanism 46). FIG. 4 corresponds to a state where the transaxle 28 is actually mounted on the vehicle. That is, the axis C1 of the electric motor 22 is arranged at the highest position in the vertical direction, the axis C3 of the ring gear 42 is arranged at the highest position, and the axis C2 of the counter shaft 36 is arranged at the lowest position in the vertical direction. Has been. 2 and 3 show a state cut along a cutting line Y indicated by a one-dot chain line in FIG.

  In FIG. 4, when the ring gear 42 rotates counterclockwise around the axis C <b> 3, the oil is scraped upward and stored in the catch tank 94 as indicated by a thick solid arrow. The oil stored in the catch tank 94 passes through a through-hole 96 parallel to the axis C1 formed in the drive shaft 32 via an oil supply hole (not shown) as shown by an arrow in FIG. Is guided to the motor chamber 84 through the clearance formed in the spline fitting portion between the drive shaft 32 and the rotor shaft 58 and the bearing 56 by the weight of the oil. A part of the oil passes through the through hole 96 and is guided to the motor chamber 84 by the dead weight of the oil through the hollow hole 98 parallel to the axis C1 formed in the rotor shaft 58 and the bearing 54. Further, the oil stored in the motor chamber 84 is circulated to the gear chamber 90 through opening holes (first opening hole 100 and second opening hole 102) described later. As described above, the cooling oil passage 99 is configured to guide the oil in the gear chamber 90 scraped up by the ring gear 42 to the motor chamber 84 via the catch tank 94. Therefore, when the second electric motor 22 is driven (heat generation), when the oil in the transaxle 28 is circulated in this way, the electric motor 22 is cooled by the circulated oil. In addition to the above, the oil stored in the catch tank 94 returns to the gear chamber 90 through the supply holes 95 and 97 shown in FIG.

  Next, the structure of the opening hole formed in the partition wall 92 that partitions the motor chamber 84 and the gear chamber 90, which is also a main part of the present invention, will be described. 5 is an enlarged view of the motor chamber 84 of FIG. 2, and is a cross-sectional view taken along a cutting line Z indicated by a one-dot chain line in FIG. 4. As a result, the motor chamber 84 below the axis C1 in FIG. 5 corresponds to the vertical lower section.

  As shown in FIG. 5, a partition wall 92 interposed between the motor chamber 84 and the gear chamber 90 has a first opening hole 100 (the opening hole of the present invention) that communicates the motor chamber 84 and the gear chamber 90. And a second opening hole 102 (corresponding to the second opening hole of the present invention). The second opening hole 102 is formed so that the motor chamber 84 and the gear chamber 90 are always communicated, and the lowermost surface thereof is positioned vertically below the vertical lowermost surface of the rotor 52 by a predetermined value. Further, the first opening hole 100 is vertically lower than the second opening hole 102, and the oil surface height (oil level) of the gear chamber 90 set in advance in the gear chamber 90 is the lowest (lowest). It is formed vertically lower than (height position). The above corresponds to, for example, when traveling at high speed. Therefore, the first opening hole 100 is prevented from exceeding the oil level.

  In addition, when the oil temperature of the motor chamber 84 reaches a predetermined oil temperature α set in advance in the first opening hole 100, the on-off valve 104 that switches the flow rate of oil flowing through the first opening hole 100 (of the present invention). Corresponding to the flow rate switching mechanism).

  The on-off valve 104 is provided in the first opening hole 100 by being screwed to the tapered surface 114 formed in the first opening hole 100 and the partition wall 92, and communicates the motor chamber 84 and the gear chamber 90 inside. A return-shaped spring receiving member 106 in which a communicating hole 108 is formed, a ball 110 having a spherical shape that closes the first opening hole 100 by being pressed by the tapered surface 114, and one end of the spring receiving member 106. The spring 112 presses the ball 110 against the inclined surface 114 of the first opening hole 100 by the elastic return force by being in contact with the other end and the ball 110.

  Here, the spring 112 is formed of a shape memory alloy, and the length of the spring 112 does not change until reaching a predetermined temperature α set in advance. (Full length) is set to be shortened. Further, the diameter of the hole on the large diameter side formed in the tapered surface 114 is larger than the diameter of the ball 110, and the diameter of the hole on the small diameter side is smaller than the diameter of the ball 110. Therefore, in the range below the predetermined temperature α, the spring 112 receives the reaction force of the spring receiving member 106, thereby pressing the ball 110 against the tapered surface 114 formed in the first opening hole 100, thereby opening and closing the valve. 104 becomes a valve closing state, and the first opening hole 100 is closed. On the other hand, when the spring 112 reaches the predetermined temperature α, the spring 112 is shortened in the axial direction, and the ball 110 enters the idle state. Accordingly, the on-off valve 104 is opened, the first opening hole 100 is communicated, and when the oil level height of the motor chamber 84 and the gear chamber 90 is different (normally the gear chamber 90 side is low), a predetermined amount of oil flows out. .

  The operation of the cooling device 101 provided in the transaxle 28 configured as described above will be described. In the transaxle 28, the oil is not stored in the catch tank 94 at the time of starting the vehicle (before traveling / cold time), so that all the oil is stored in the motor chamber 84 and the gear chamber 90. The oil chamber height of both the motor chamber 84 and the gear chamber 90 (oil level) is the oil surface height A (oil level A) indicated by the broken line in FIG. Since the oil is in a low temperature state, the on-off valve 104 is closed and the first opening hole 100 is shut off.

  When the vehicle starts traveling, the oil is scraped up by the ring gear 42, and the oil is supplied to each lubricating portion while the oil is stored in the catch tank 94. When sufficient oil is stored in the catch tank 94, the oil level in the gear chamber 90 is lowered to the oil level C (oil level C) indicated by the broken line. As a result, the contact area of the ring gear 42 immersed in the oil stored in the gear chamber 90 is reduced, and the stirring resistance due to the low temperature and high viscosity oil is reduced. At this time, in the motor chamber 84, it becomes the height of the lower surface of the second opening hole 102, that is, the maximum oil level height M (oil level M) of the motor chamber 84 during traveling. The oil level in the motor chamber 84 does not exceed the oil level M, and excess oil supplied to the motor chamber 84 flows out from the second opening hole 102 to the gear chamber 90 side. Therefore, even if the rotor 52 of the electric motor 22 rotates, the oil level height of the motor chamber 84 does not exceed the oil level M set vertically below the vertical bottom surface of the rotor 52 by a predetermined value. 52 prevents the oil from being stirred. The predetermined value is set to a value near the minimum value in a range in which the rotor 52 does not contact the oil in the motor chamber 84, for example.

  Next, when the electric motor 22 is driven, the temperature of the stator 50 and the stator coil 51 rises, and when the oil temperature in the motor chamber 84 reaches a predetermined temperature α, the total length (axial length) of the spring 112 is shortened. Then, the ball 110 moves freely, the on-off valve 104 is opened, and the first opening hole 100 is communicated. Therefore, the oil level height (oil level M) of the motor chamber 84 is higher in the vertical direction than the oil level height (oil level C) of the gear chamber. The oil in the motor chamber 84 and the gear chamber 90 is circulated. As a result, the oil in the gear chamber 90 flows into the motor chamber 84. At this time, the oil level of the gear chamber 90 rises to the oil level B. Also, the oil level of the motor chamber 84 is the oil level B as in the gear chamber 90. The oil in the gear chamber 90 increases when the oil in the motor chamber 84 flows in, so the oil viscosity is small even when the oil level is high (oil level B). No stirring resistance is generated.

  Here, when the driving of the electric motor 22 is limited to a range below a predetermined vehicle speed Va, specifically, a range of a relatively low vehicle speed, the temperature of the motor chamber 84 increases according to the driving of the electric motor 22 at a low vehicle speed. On the other hand, the oil in the gear chamber 90 is lower in temperature than the oil temperature in the motor chamber 84 because the amount of heat generated by the stirring by the ring gear 42 is small. Therefore, when the low temperature oil in the gear chamber 90 flows into the motor chamber 84, the oil temperature in the motor chamber 84 is lowered and the electric motor 22 is cooled. Further, when the vehicle speed increases to exceed the predetermined vehicle speed Va and the vehicle travels at a high vehicle speed, the operation of the electric motor 22 is stopped. Even at this time, the rotor 52 is rotated by the accompanying rotation of the rear wheel 26. When the operation of the electric motor 22 is stopped and the oil temperature in the motor chamber 84 falls below a predetermined temperature α, the spring 112 of the on-off valve 104 returns to its original length, and the ball 112 is tapered by the spring 112. Pressed against the surface 114, the on-off valve 104 is closed, and the first opening hole 100 is closed. As a result, oil is stored again in the motor chamber 84 and the oil level becomes the oil level M, and the oil level in the gear chamber becomes the oil level C, so that the stirring resistance is suppressed. Note that the predetermined vehicle speed Va is set in advance based on experiments or the like, and is set to a vehicle speed that should preferably travel by the electric motor 22, for example.

  From the above, when the drive of the electric motor 22 is limited to a low vehicle speed range, the oil in the gear chamber 90 that is cooler than the oil temperature in the motor chamber 84 circulates in a state where the oil temperature in the motor chamber 84 is high when the motor is driven. Thus, the electric motor 22 is cooled. Further, at the time of high vehicle speed when the oil temperature of the gear chamber 90 becomes high, the oil in the gear chamber 90 moves to the motor chamber 84 side and is stored, so that the oil level of the gear chamber 90 is maintained at a low state. Loss associated with oil agitation is reduced. Even at this time, since the oil level of the motor chamber 84 does not exceed the oil level M, oil dragging of the rotor 52 is prevented. Therefore, by setting the optimal oil level according to the oil temperature, the motor 22 is efficiently cooled while the oil agitation resistance is suppressed, so that the loss of transmission efficiency is minimized. Fuel consumption will be improved.

  As described above, according to the present embodiment, when the electric motor 22 is driven and the heat of the motor 22 increases the oil temperature of the oil in the motor chamber 84 and reaches the predetermined temperature α, the on-off valve 104 is opened and the second valve 104 is opened. One opening hole 100 is communicated. In such a case, the oil in the gear chamber 90 is guided to the motor chamber 84 through the cooling oil passage 99 and is circulated from the first opening hole 100 to the gear chamber 90 again, so that the oil temperature in the motor chamber 84 is lowered. The electric motor 22 is cooled. On the other hand, when the oil temperature in the motor chamber 84 does not reach the predetermined temperature α, specifically, when the oil temperature in the motor chamber 84 is low, the on-off valve 104 is closed and the first opening hole 100 is shut off. Thus, the oil stored in the motor chamber 84 increases and the oil stored in the gear chamber 90 decreases. Accordingly, the height of the oil surface stored in the gear chamber 90 is reduced, and the stirring resistance when the ring gear 42 stirs the oil is reduced. As described above, the on-off valve 104 is provided to efficiently cool the electric motor 22 by circulating oil when the electric motor 22 needs to be cooled. When the electric motor 22 does not need to be cooled, the oil is supplied to the motor chamber 84. By accumulating and lowering the height of the oil surface of the gear chamber 90, the stirring resistance of the ring gear 42 can be suppressed and the reduction in transmission efficiency can be suppressed.

  Further, according to the present embodiment, when the oil temperature in the motor chamber 84 does not reach the predetermined temperature α in the on-off valve 104, the on-off valve 104 is closed and the motor chamber 84 and the gear chamber 90 are communicated. As a result, the oil stored in the motor chamber 84 increases, while the oil in the gear chamber 90 decreases and the oil level decreases. Therefore, a decrease in transmission efficiency is suppressed as the stirring resistance when the ring gear 42 stirs the oil is reduced. When the oil temperature in the motor chamber 84 reaches a predetermined temperature α, the on-off valve 104 is opened and the motor chamber 84 and the gear chamber 90 communicate with each other, so that the oil in the gear chamber 90 passes through the cooling oil passage 99. As a result, the oil flows into the motor chamber 84 and is recirculated to the gear chamber 90. As a result, the oil is actively circulated, so that the oil temperature in the motor chamber 84 is lowered and the electric motor 22 is cooled. From the above, in a temperature state where the cooling of the electric motor 22 is not necessary, the oil is stored in the motor chamber 84, so that a decrease in transmission efficiency is suppressed. It is possible to efficiently cool the electric motor 22 by circulating the air to the motor.

  Further, according to the present embodiment, the partition wall 92 is formed with the second opening hole 102 that is formed vertically below the lowermost rotor surface of the electric motor 22 by a predetermined value and always communicates the motor chamber 84 and the gear chamber 90. Therefore, the oil level of the motor chamber 84 does not exceed the lowermost surface of the rotor 52 even at the highest position. Therefore, even when the electric motor 22 rotates, the oil is prevented from being agitated by the rotor 52 of the electric motor 22, so that loss due to the oil accompanying the rotor 52 is prevented.

  Further, according to the present embodiment, the cooling oil passage 99 is provided with the catch tank 94 that temporarily stores the oil scraped up by the ring gear 42, so that the oil scraped up by the ring gear 42 is caught by the catch tank 94. By storing in the tank 94, the oil temperature of the gear chamber 90 can be adjusted to an optimum height.

  Further, according to the present embodiment, since the electric motor 22 is driven in a range where the vehicle speed of the vehicle is equal to or lower than the predetermined vehicle speed, the electric motor 22 is driven in the range of the predetermined vehicle speed, and the oil temperature of the motor chamber 84 rises. On the other hand, since the vehicle speed is equal to or lower than the predetermined vehicle speed, the rotational speed of the ring gear 42 is low and the oil temperature on the gear chamber 90 side is low. At this time, when the oil temperature in the motor chamber 84 reaches a predetermined temperature α, the low temperature oil in the gear chamber 90 is actively circulated through the motor chamber 84, so that the oil temperature in the motor chamber 84 decreases. Thus, the electric motor 22 is cooled. Further, when the vehicle speed exceeds the predetermined vehicle speed, the electric motor 22 is stopped. Therefore, when the oil temperature in the motor chamber 84 decreases and becomes equal to or lower than the predetermined temperature α, the oil from the motor chamber 84 to the gear chamber 90 is transferred by the on-off valve 104. Flow is suppressed. At this time, as the oil stored in the motor chamber 84 increases, the oil in the gear chamber 90 decreases, the oil level becomes lower, and the stirring resistance is suppressed.

  Further, according to this embodiment, the spring 112 is made of a shape memory alloy, and until the oil temperature reaches a predetermined temperature α, the ball 110 is pressed against the tapered surface 114 to close the first opening hole 100, and the oil When the temperature reaches a predetermined temperature α, the ball 110 moves freely by the shortening of the overall length, and the first opening hole 100 is communicated, so that the oil level of the gear chamber 90 can be adjusted appropriately. In addition, the on-off valve 104 that efficiently cools the electric motor 22 can be configured.

  Next, another embodiment of the present invention will be described. In the following description, parts common to those in the above-described embodiment are denoted by the same reference numerals and description thereof is omitted.

  FIG. 6 is a cross-sectional view of the motor chamber 84 of the rear transaxle 150 according to another embodiment of the present invention, and corresponds to FIG. 5 of the above-described embodiment. When the rear transaxle 150 in FIG. 6 is compared with the rear transaxle 28 in FIG. 5 described above, the on-off valve 104 shown in FIG. 5 is replaced with an orifice 154 (in the throttle and flow rate switching mechanism of the present invention). Support). In addition to the above, since there is no difference from the rear transaxle 28, the configuration and operation of the orifice 154 will be described below.

  The orifice 154 has a throttle hole 156 having a smaller diameter than the first opening hole 100, and the motor chamber 84 and the gear chamber 90 are always in communication with each other through the throttle hole 156. Here, the hole diameter d of the throttle hole 156 (in other words, the opening area of the throttle hole 156) is experimentally obtained in advance, and when the oil temperature of the motor chamber 84 reaches a predetermined temperature α set in advance. The oil flowing through the throttle hole 156 (orifice 154) is set to a predetermined flow rate Qa. As shown in FIG. 7, generally, as the oil temperature T rises, the viscosity of the oil decreases, so the flow rate Q of the oil flowing through the throttle hole 156 increases. Further, the flow rate Q increases as the diameter d of the throttle hole 156 increases. From the above, based on the viscosity when the oil temperature T reaches the predetermined temperature α, the optimum diameter d of the throttle hole 156 that sets the predetermined flow rate Qa when the oil temperature T reaches the predetermined temperature α is set. Is done. The predetermined flow rate Qa is set to such a flow rate that the oil in the gear chamber 90 is sufficiently supplied to the motor chamber 84 and the oil stored in the motor chamber 84 is suitably cooled based on experiments and the like.

  The operation of the cooling device 152 provided in the transaxle 150 configured as described above will be described. In the transaxle 150, when the vehicle is started (before traveling), no oil is stored in the catch tank 94. Therefore, all the oil is stored in the motor chamber 84 and the gear chamber 90. Accordingly, the oil level heights (oil levels) of the motor chamber 84 and the gear chamber 90 are both the oil level A indicated by the broken line shown in FIG.

  When the vehicle starts running, the oil is scraped up by the ring gear 42 of the differential mechanism 46, and the oil is supplied to each lubricating portion while the oil is stored in the catch tank 94. When sufficient oil is stored in the catch tank 94, the oil level in the gear chamber 90 is lowered to an oil level C indicated by a broken line. Immediately after the start of vehicle travel, the oil temperature is low, and the flow rate from the motor chamber 84 to the gear chamber 90 through the orifice 154 is less than the oil scooped up by the ring gear 42 in the gear chamber 90. Therefore, the oil level in the gear chamber 90 is lower than the oil level in the motor chamber 84. As a result, the contact area of the ring gear 42 immersed in the oil stored in the gear chamber 90 is reduced, and the stirring resistance due to the low temperature and high viscosity oil is reduced. Further, at this time, in the motor chamber 84, the oil scooped up in the gear chamber 90 is supplied to the motor chamber 84 via the catch tank 94 and the like, so that the oil level in the motor chamber 84 becomes high, and the maximum is shown in FIG. The oil level M is indicated by a broken line 6.

  When the electric motor 22 is driven, the temperature of the stator 50 and the stator coil 51 of the electric motor 22 increases, and when the oil temperature in the motor chamber 84 reaches a predetermined temperature α, the flow rate flowing through the orifice 154 becomes the predetermined flow rate Qa. Sufficient oil flows from the motor chamber 84 into the gear chamber 90. Therefore, the oil circulates suitably in the rear transaxle 150, and the oil in the gear chamber 90 flows into the motor chamber 84. At this time, the oil level in the gear chamber 90 rises to an oil level B indicated by a broken line in FIG. In the motor chamber 84, the oil level is the oil level B as in the gear chamber 90. Note that the oil in the gear chamber 90 rises when the oil in the motor chamber 84 flows in, so the oil viscosity is small even when the oil level rises (oil level B). A large stirring resistance does not occur.

  Further, when the drive of the electric motor 22 is limited to a range of low vehicle speed, the temperature of the motor chamber 84 rises according to the drive of the electric motor 22 at the low vehicle speed, but the oil in the gear chamber 90 has a small amount of heat generation, so the motor chamber The oil temperature is lower than 84 oil temperature. Therefore, when the oil in the gear chamber 90 flows into the motor chamber 84, the oil temperature in the motor chamber 84 is lowered and the electric motor 22 is cooled. Further, when the vehicle speed increases and the vehicle travels at a high speed, the operation of the electric motor 22 is stopped. When the operation of the electric motor 22 is stopped and the oil temperature in the motor chamber 84 falls below the predetermined temperature α, the amount of oil flowing from the motor chamber 84 into the gear chamber 90 decreases. As a result, the oil stored in the motor chamber 84 is increased again, while the oil level in the gear chamber 90 is decreased, so that the stirring resistance is suppressed.

  As described above, according to this embodiment, when the electric motor 22 is driven and the oil temperature of the motor chamber 84 rises due to the heat generation and reaches the predetermined temperature α, the flow rate flowing through the first opening hole 100 is increased. The predetermined flow rate Qa is set in advance. In such a case, the oil in the gear chamber 84 is guided to the motor chamber 84 through the cooling oil passage 99 and is circulated from the first opening hole 100 to the gear chamber 90 again, so that the oil temperature in the motor chamber 84 decreases. The electric motor 22 is cooled. On the other hand, when the oil temperature in the motor chamber 84 does not reach the predetermined temperature α, specifically, when the oil temperature in the motor chamber 84 is low, the flow rate flowing from the motor chamber 84 into the gear chamber 90 is reduced by the orifice 154. As a result, the oil stored in the motor chamber 84 increases and the oil stored in the gear chamber 90 decreases. Accordingly, the height of the oil surface stored in the gear chamber 90 is reduced, and the stirring resistance when the ring gear 42 stirs the oil is reduced. As described above, by providing the orifice 154, when the motor 22 needs to be cooled, the oil is circulated to cool the motor 22, and when the motor 22 does not need to be cooled, the oil is stored in the motor chamber 84 and the gear is By reducing the height of the oil level in the chamber 90, the stirring resistance of the ring gear 42 can be suppressed, and a decrease in transmission efficiency can be suppressed.

  Further, according to the present embodiment, when the oil temperature in the motor chamber 84 does not reach the predetermined temperature α based on the orifice 154, the amount of oil flowing into the gear chamber 90 reaches the predetermined flow rate Qa. As the oil that does not reach and flows into the gear chamber 90 is reduced, the oil level of the gear chamber 90 decreases. Therefore, a decrease in transmission efficiency is suppressed as the stirring resistance when the ring gear 42 stirs the oil is reduced. When the oil temperature in the motor chamber 84 reaches a predetermined temperature α, the oil in the gear chamber 90 passes through the cooling oil passage 99 and passes from the first opening hole 100 to the gear chamber 90 via the motor 22 and the motor chamber 84. As the circulating oil increases, the oil is actively circulated and the electric motor 22 is cooled. From the above, in a temperature state where the cooling of the electric motor 22 is not required, the oil stored in the motor chamber 84 increases, the oil in the gear chamber 90 decreases, and the stirring resistance is reduced, thereby suppressing a decrease in transmission efficiency. When the temperature at which the electric motor 22 needs to be cooled is reached, the oil is actively circulated so that the electric motor 22 can be efficiently cooled. The above effects can be obtained even with a relatively simple configuration.

  As mentioned above, although the Example of this invention was described in detail based on drawing, this invention is applied also in another aspect.

  For example, in the above-described embodiment, the on-off valve 104 is closed by pressing the ball 110 against the first opening hole 100 with the spring 112 made of a shape memory alloy, and when the oil temperature reaches the predetermined temperature α, the spring 112 However, the on-off valve 104 is not necessarily limited to the above-described structure. For example, a thermostat is used, and the first opening hole 100 is closed until the oil temperature reaches a predetermined temperature α, and the first opening hole 100 is opened when the oil temperature reaches the predetermined temperature α. It doesn't matter. Alternatively, for example, a temperature sensor (such as a thermocouple) that detects the oil temperature of the motor chamber 84, and a solenoid valve that communicates the first opening hole 100 when the oil temperature detected by the temperature sensor reaches a predetermined temperature α; You may be comprised from these. That is, any open / close valve that can open and close the first opening hole 100 according to the oil temperature can be freely changed.

  In the above-described embodiment, the present invention is applied to the rear transaxle 28. However, the present invention can also be applied to a front transaxle. That is, the present invention can be applied as long as the motor chamber in which the electric motor is accommodated and the gear chamber in which the gear is accommodated are adjacent to each other with a partition wall therebetween.

  In the above-described embodiment, oil is scraped up by the ring gear 42 of the differential mechanism 46. However, the present invention is not limited to the ring gear 42 of the differential mechanism 46, and a predetermined gear is stored in the lower part. The present invention can be applied to any structure that is immersed in the oil.

  In the above-described embodiment, the motor is operated at a low vehicle speed. However, this is a use example for the purpose of starting assistance on a low μ road, and the operation of the motor is not limited to a low speed. .

  The above description is only an embodiment, and the present invention can be implemented in variously modified and improved forms based on the knowledge of those skilled in the art.

22: Electric motor 28, 150: Rear transaxle (vehicle power transmission device)
30: Transaxle case (case)
42: Ring gear (gear)
84: Motor chamber 90: Gear chamber 92: Partition wall 94: Catch tank 99: Cooling oil passage 100: First opening hole (opening hole)
101, 152: Cooling device 102: Second opening hole (second opening hole)
104: On-off valve (flow rate switching mechanism)
106: Spring receiving member 110: Ball 112: Spring 114: Tapered surface 154: Orifice (throttle, flow rate switching mechanism)
α: Predetermined temperature

Claims (7)

In the cooling device for a vehicle power transmission device configured to include an electric motor in the case,
A motor chamber configured to store the electric motor and store oil in a vertically lower portion;
A gear that is formed adjacent to the motor chamber with a partition wall, and that accommodates a gear that rotates when the vehicle travels, and that is configured to store oil in a state where a part of the gear is immersed in a vertically lower portion. Room,
A cooling oil passage that guides the oil in the gear chamber, which has been scraped by rotation of the gear, to the motor chamber of the electric motor;
An opening hole that is formed vertically below the preset oil level of the gear chamber of the partition wall, and that connects the motor chamber and the gear chamber;
A flow rate switching mechanism which is provided in the opening hole and switches the flow rate of oil flowing through the opening hole to a predetermined flow rate when the oil temperature in the motor chamber reaches a predetermined temperature;
A cooling device for a vehicle power transmission device, comprising:   The cooling device for a vehicle power transmission device according to claim 1, wherein the flow rate switching mechanism is an on-off valve that is opened when the oil temperature in the motor chamber reaches a predetermined temperature.   The flow rate switching mechanism is a throttle that adjusts the oil flowing through the opening hole to a predetermined flow rate that is preset when the oil temperature in the motor chamber reaches a predetermined temperature. A cooling device for a vehicle power transmission device.   The partition wall is formed with a second opening hole formed vertically below a lowermost rotor surface of the electric motor by a predetermined value and always communicating the motor chamber and the gear chamber. Item 4. The cooling device for a vehicle power transmission device according to any one of Items 1 to 3.   The cooling of the vehicle power transmission device according to any one of claims 1 to 4, wherein the cooling oil passage is provided with a catch tank that temporarily stores oil scraped up by the gear. apparatus.   The cooling apparatus for a vehicle power transmission device according to any one of claims 1 to 5, wherein the electric motor is driven in a range where a vehicle speed of the vehicle is equal to or lower than a predetermined vehicle speed set in advance.   The on-off valve includes a tapered surface formed in the opening hole, a ball that closes the opening hole by being pressed by the tapered surface, and the ball until the oil temperature reaches a predetermined temperature. A spring made of a shape memory alloy that presses against the surface to close the opening hole, and when the oil temperature reaches a predetermined temperature, the ball is caused to move freely by reducing the overall length, and the opening hole The cooling device for a vehicle power transmission device according to claim 2, further comprising a spring receiving member that is provided on the spring and receives a reaction force when the spring presses the ball.

Images