JP2013110922A - Coolant pipe - Google Patents

Abstract

PROBLEM TO BE SOLVED: To stabilize the discharge direction of a coolant discharged from a discharge hole provided on a coolant pipe side wall and inhibit the increase of the weight in a coolant pipe introducing the coolant to a predetermined position of a rotary electric machine.SOLUTION: A discharge hole 32, which discharges a coolant toward a predetermined portion of a rotary electric machine 12, is provided on a side wall 28 of a cylindrical coolant pipe 26. The side wall 28 is thickly formed around the discharge hole 32. This structure inhibits influences of a velocity component even if the velocity of the coolant flowing in the coolant pipe 26 is increased and stabilizes the discharge direction. Further, since the side wall 28 is thickly formed only around the discharge hole 32, the weight increase is inhibited, compared to a case that the entire portion is thickly formed.

Description

  The present invention relates to cooling of a rotating electrical machine, and more particularly to a structure of a coolant pipe that guides coolant to a predetermined portion of the rotating electrical machine.

  An electric motor that converts electrical energy into rotational kinetic energy, a generator that converts rotational kinetic energy into electrical energy, and an electric device that functions as both the motor and the generator are known. Hereinafter, these electric devices are referred to as rotating electric machines.

  The rotating electrical machine has two members that are arranged coaxially and relatively rotate. Normally, one is fixed and the other rotates. A coil is arranged on a fixed member (stator), and a rotating magnetic field is formed by supplying electric power to the coil. The other member (rotor) is rotated by the interaction with the magnetic field.

  The rotating electrical machine generates heat by its operation and the temperature rises. In order to prevent overheating of a rotating electrical machine, a technique of cooling using a liquid is known. For example, in Patent Document 1 below, coolant (oil) discharged from an oil pump is sent to the upper side of a rotating electrical machine by a pipe, and discharged from a discharge hole provided on a side surface of the pipe toward a predetermined portion of the rotating electrical machine. The technology is described.

JP 2005-253263 A

  The cooling liquid discharged from the pipe is not discharged in a direction perpendicular to the direction in which the pipe extends but is discharged obliquely if the velocity component when flowing in the pipe remains. Increasing the pipe thickness can reduce the effect of flow velocity in the pipe, but this increases the weight and material of the pipe.

  An object of the present invention is to stabilize the discharge direction of the coolant and suppress an increase in the weight of the pipe.

  The cooling liquid pipe according to the present invention is a cooling liquid pipe that guides the cooling liquid to a predetermined position of the rotating electrical machine, and has a discharge hole for discharging the cooling liquid on the side wall. It is thicker than the part.

  Moreover, the thickness of the surrounding side wall can be increased as the discharge hole has a plurality of discharge holes having different diameters and has a larger diameter.

  Increasing the thickness of the coolant pipe side wall around the discharge hole stabilizes the coolant discharge direction. On the other side of the discharge hole, reducing the pipe side wall thickness reduces the increase in weight. be able to.

It is a figure which shows schematic structure of this embodiment. It is a figure which shows the relationship between the thickness of a coolant pipe side wall, and the discharge angle of the discharged coolant. It is a figure which shows the relationship between the hole diameter and hole length of a discharge hole for achieving an allowable discharge angle. It is a figure which shows the other example of a coolant pipe.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. FIG. 1 is a cross-sectional view showing a main part of a rotating electrical machine 12 housed in a case 10 and a cooling system 14 of the rotating electrical machine. An example of such a device is a transaxle for a hybrid vehicle. The transaxle is a kind of power transmission device that shifts the output from a prime mover such as an internal combustion engine and sends it to drive wheels, and generally includes a speed change mechanism and a final speed reduction mechanism. In a hybrid vehicle that travels by the output of a rotating electrical machine in addition to an internal combustion engine, a vehicle having a rotating electrical machine for driving a vehicle in a transaxle is known. The rotating electrical machine is housed in a transaxle case that houses the speed change mechanism and the final speed reduction mechanism.

  The rotating electrical machine 12 includes a rotor 16 and a substantially cylindrical stator 18 disposed so as to surround the rotor 16. The stator 18 has a stator core 20 formed by laminating electromagnetic steel plates in the direction of the rotation axis of the rotating electrical machine (hereinafter referred to as the rotation axis direction). This electromagnetic steel sheet has a shape in which concavities and convexities are formed in a comb-tooth shape on the inner periphery of the annular plate, and is laminated so that the concavities and convexities are aligned. As a result, convex portions extending along the rotation axis direction of the rotating electrical machine are arranged in the circumferential direction on the inner circumferential surface of the cylinder of the stator core 20. A conductive wire is wound around the convex portion to form the coil 22. The portion of the coil 22 that protrudes from the cylindrical end surface of the stator core 20 is called a coil end. In FIG. 1, the coil end is indicated by reference numeral 23.

  Since the rotating electrical machine 12 housed in the case 10 cannot be expected to be cooled by outside air, it is cooled by supplying a coolant. In the case of the rotating electrical machine 12 housed in the transaxle, the working fluid of the hydraulic actuator (clutch, brake, etc.) of the transmission mechanism can be used as the coolant. The hydraulic fluid also serves as a lubricating oil for a transmission mechanism and the like. The coolant is sent out by a pump 24 and sent to a predetermined part of the rotating electrical machine 12 through a flow path and piping provided in the case. The pump 24 may be a pump that sends hydraulic fluid for lubrication of each mechanism provided in the case and operation of the actuator. The pump 24 may be driven by the rotating electrical machine 12 and may be driven by an internal combustion engine if it is a hybrid vehicle. In addition to the rotating electrical machine 12, an electric motor for driving the pump 24 may be provided.

  The coolant sent from the pump 24 reaches a coolant pipe 26 disposed above the rotating electrical machine 12. The coolant pipe 26 has a cylindrical shape, for example, a cylindrical side wall 28 and an end wall 30 provided so as to close one end of the cylinder. The coolant is fed into the coolant pipe 26 from the open end of the cylinder. The side wall 28 has a discharge hole 32 on the surface facing the rotating electrical machine 12. A plurality of, for example, three discharge holes 32 are provided along the length direction of the coolant pipe 26. Of the three discharge holes 32, two (32A, 32B) are disposed at positions facing the coil ends 23 on both sides of the stator core 20, and the remaining one is disposed at a position facing the outer periphery of the stator core 20. Yes. Each discharge hole 32 is provided such that its axis is orthogonal to the axis of the coolant pipe 26.

  The discharge flow from the discharge hole 32 may include a velocity component of the coolant when flowing in the coolant pipe 26. As the flow in the cooling liquid pipe 26 becomes faster, the influence becomes larger, and the discharge flow is a direction perpendicular to the axis of the cooling liquid pipe 26 or a direction along the axis of the discharge hole 32 as shown by a broken line in FIG. With an angle to When the discharge flow is inclined in this way, the cooling liquid may not be applied to the intended position and cooling may not be performed sufficiently. When the pump 24 is driven by the internal combustion engine or the rotating electrical machine 12, the operation speed of the pump 24 depends on the speed of the internal combustion engine or the like, and therefore the speed of the coolant in the coolant pipe 26 also depends on the speed of the internal combustion engine or the like. Fluctuate. Further, when the coolant (working fluid) is also sent to the transmission mechanism or the like, the discharge flow rate of the pump 24 is determined with priority given to the request of the transmission mechanism or the like. For these reasons, the flow velocity in the coolant pipe 26 varies, and therefore the direction of the discharge flow can be oblique.

  By increasing the thickness of the side wall of the coolant pipe, the angle of the discharge flow can be made closer to the direction perpendicular to the axis of the coolant pipe. FIG. 2 is a diagram showing the discharge angle of the discharge flow with respect to the thickness of the side wall of the coolant pipe when the inner diameter of the discharge hole and the flow velocity in the coolant pipe are fixed. The discharge angle is 0 ° in the direction perpendicular to the axis of the coolant pipe. As can be understood from this figure, the discharge angle approaches 0 ° as the thickness of the side wall of the coolant pipe increases. That is, by increasing the length of the discharge hole with respect to the inner diameter of the discharge hole, the direction of the discharge flow can be set to a direction perpendicular to the axis of the coolant pipe. On the other hand, if the thickness of the entire side wall of the coolant pipe is increased in order to increase the length of the discharge hole, the weight and the amount of material used are increased.

  Therefore, in the coolant pipe 26 of this embodiment, the thickness of the side wall around the discharge hole 32 is increased while the overall thickness of the side wall is thin. Specifically, the side wall 28 is provided with a portion raised in the shape of a cone or a truncated cone, and the discharge hole 32 is formed in the center of the cone.

  FIG. 3 is a diagram showing the relationship between the length of the discharge hole and the diameter (hole diameter) when the direction of the discharge flow is within an allowable range. The points plotted in the figure represent the hole diameter and the hole length in which the direction of the discharge flow is within the allowable range even when the flow velocity in the coolant pipe is high. From this, it can be understood that the ratio of the hole length to the hole diameter may be set to a certain value or more in order to keep the direction of the discharge flow within a certain range. That is, when the hole diameter is large, the hole length is increased. When the hole diameter is small, the hole length may be small.

  If the required amount of coolant varies depending on the location of the rotating electrical machine 12, this can be adjusted by the diameter of the discharge hole 32. In other words, the hole diameter of the discharge hole 32 corresponding to the portion requiring a large amount of cooling liquid is increased. In this case, the hole length is adjusted according to the hole diameter. That is, in the discharge hole having a large hole diameter, the hole length is also increased. Increasing the length of the hole can be achieved by increasing the height of the cone or frustoconical shape formed around the discharge hole and increasing the thickness of this side wall. When it is necessary to supply more cooling liquid to the coil end 23 than the stator core 20, the hole diameters of the discharge holes 32A and 32B facing the coil end 23 are increased and the length is also increased.

  A plurality of discharge holes may be provided at the same position in the axial direction of the coolant pipe. That is, it is possible to arrange a plurality of discharge ports on one circumference.

  FIG. 4 is a diagram illustrating an example in which a plurality of discharge holes are provided at the same position in the axial direction of the coolant pipe. FIG. 4 is a view showing a cross section perpendicular to the axis of the coolant pipe 34. The coolant pipe 34 has two discharge holes 36A and 36B in the cross section shown in FIG. The discharge holes 36 </ b> A and 36 </ b> B are arranged such that their axes are orthogonal to the axis of the coolant pipe 34. Further, it is arranged slightly swinging left and right, not directly under the coolant pipe 34. Thereby, the coolant applied to the coil end 23 is transmitted along the circumference of the coil end 23 and easily flows to the side of the coil end 23.

  Furthermore, in the example of FIG. 4, the hole diameter of the discharge hole 36A is larger than the hole diameter of the discharge hole 36B. Accordingly, the thickness of the side wall of the coolant pipe 34 is also thicker around the discharge hole 36A than around the discharge hole 36B. In addition, the thickness of the side wall around the discharge hole 36B is thicker than other portions. By using different hole diameters, more cooling liquid can be discharged from the discharge holes 36A. Thus, by setting the asymmetric discharge amount, it is possible to adapt to the case where the coolant pipe 34 is offset from the coil end 23 by the dimension d as shown in FIG. When the coolant pipe 34 is offset to the right with respect to the center line of the coil end 23 as shown in FIG. 4, when the coolant is discharged from the coolant pipe 34 equally to the left and right, the cooling that flows through the left half of the coil end 23 is performed. Less liquid. In order to correct this, the diameter of the discharge hole 36A on the left side is increased so that more coolant is sent to the left side.

  12 rotating electrical machines, 18 stators, 20 stator cores, 22 coils, 23 coil ends, 24 pumps, 26, 34 coolant pipes, 28 side walls, 32, 36 discharge holes.

Claims (2)

  A coolant pipe that guides coolant to a predetermined position of the rotating electrical machine, and the coolant pipe has a discharge hole for discharging the coolant on the side wall, and the thickness of the side wall around the discharge hole is the other part. A coolant pipe that is thicker than.   The coolant pipe according to claim 1, wherein the coolant pipe has a plurality of discharge holes having different hole diameters, and a discharge hole having a larger hole diameter has a thicker side wall.

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