Insert member for rotating electrical machine

Abstract

To provide an insert member, thermal conductivity of which can be favorably controlled.SOLUTION: A substantially cylindrical insert member is cast in an aluminum alloy motor case of a rotary electric machine. A plurality of uneven portions is formed on an outer peripheral surface of the insert member. In a range of predetermined axial direction length, in one cut surface which appears when cutting the insert member into two parts along an axial direction, by a virtual plane including a central axis of the insert member, when setting a line along a contour of the outer peripheral surface including the contour of the plurality of uneven portions as a contour line, an outer peripheral surface length ratio which is a value obtained by dividing the length of the contour line by predetermined axial direction length becomes 1.15 or more.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to an insert member for a rotating electrical machine.

Background Art

[0002] Generally, an aluminum alloy is often used as a structural member of a motor case of a rotating electrical machine. Further, in the motor case, in a portion where a stator is disposed, in some cases, a high-strength member formed in a substantially cylindrical shape from an iron-based material is used as an insert member to supplement strength. In relation to this, it has been proposed to provide irregularities on the outer peripheral surface of the insert member that is integrated with the motor case by press-fitting or casting (see, for example, Patent Documents 1 and 2).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, an insert member formed of an iron-based material is inferior in thermal conductivity compared to an aluminum alloy that is generally often used as a structural member of a motor case. Therefore, while the bonding strength with the motor case is increased by the irregularities provided on the outer peripheral surface of the insert member, heat generated by a heat generating body such as a stator cannot be efficiently radiated to the outside, which may lead to a decrease in the output of the motor and a decrease in the magnetic force of a magnet used in the motor.

[0005] The technology of the present invention has been made in view of the above-described circumstances, and an object thereof is to provide an insert member capable of favorably controlling the thermal conductivity at the interface between the insert member and the motor case.

Means for Solving the Problem

[0006] In order to solve the above problems, the technology of the present invention adopts the following configuration. The insert member for a rotating electrical machine as one aspect of the technology according to the present invention is a substantially cylindrical insert member cast into an aluminum alloy motor case of a rotating electrical machine. On the outer peripheral surface of the insert member, uneven portions including concave portions and convex portions are formed. When the insert member is cut axially into two parts by a virtual plane including the central axis of the insert member, in one of the cut surfaces that appear one by one on both sides of the central axis, when a line along the contour of the outer peripheral surface including the contour of the uneven portions in a range of a predetermined axial length is defined as a contour line, the outer peripheral surface length ratio, which is the value obtained by dividing the length of the contour line by the predetermined axial length, is 1.15 or more.

[0007] Further, in the range of the predetermined axial length, when a line segment parallel to the inner peripheral surface of the insert member is overlapped with the cut surface, a solid portion region where the insert member overlaps the line segment on the line segment and a non-solid portion region where the insert member does not overlap the line segment on the line segment are defined. On the line segment, in the range of the predetermined axial length, a value indicating the ratio of the solid portion region is defined as the solid portion ratio. In the cut surface of the insert member, the line segment is moved at a predetermined pitch along the height direction of the uneven portion from the tip of the convex portion that protrudes most in the uneven portion toward the base end side of the convex portion, and the values of the solid portion ratio at each measurement point are plotted in order. The solid portion ratio is represented on the horizontal axis. Also, taking the figure with the distance from the tip portion in the height direction represented on the vertical axis as the measurement height as the solid part aggregation diagram, taking the average of the solid part ratios at each measurement point based on the plurality of the cross-sectional views as the average solid part ratio, and using the solid part aggregation diagram in which the average solid part ratios are plotted in order as the average solid part aggregation diagram, in the average solid part aggregation diagram, taking the position where the average solid part ratio is 0 as the tip portion on the drawing, and taking the position where the average solid part ratio first exceeds 0.98 when plotted in order from the tip portion side to the base end portion side as the base end portion on the drawing, when the distance from the tip portion on the drawing to the base end portion on the drawing is taken as the average maximum height of the uneven portion, the average maximum height of the uneven portion may be 0.15 mm or more and 1.50 mm or less.

[0008] Further, when taking the average solid part ratio at the position where the height is moved 0.10 mm from the base end portion on the drawing toward the tip portion on the drawing as A, and taking the value obtained by dividing the outer peripheral surface length ratio by A as the first interface parameter, the first interface parameter may be 1.30 or more.

[0009] Also, when taking half of the value obtained by subtracting the inner diameter from the outer diameter of the insert member as the thickness of the insert member, the thickness of the insert member may be 0.8% or more of the outer diameter of the insert member.

[0010] Also, the outer peripheral surface may be subjected to a roughening treatment.

[0011] Also, the outer peripheral surface of the insert member may have at least one of a region where the outer peripheral surface length ratio is less than 1.15 and a region where the first interface parameter is less than 1.30 in a part in the axial direction.

[0012] Further, in the average solid part aggregation diagram, taking the value obtained by subtracting the average solid part ratio at a certain measurement height from the average solid part ratio at the base end portion on the drawing as the average non-solid part ratio, and when taking the average non-solid part ratio at the position where the height is moved 0.10 mm from the base end portion on the drawing toward the tip portion on the drawing as B, 0.10 / B ≤ 1.30 may be satisfied.

[0013] Also, in the average solid part aggregation diagram, when the value obtained by subtracting the average solid part ratio at a certain measurement height from the average solid part ratio at the base end part on the diagram is defined as the average non-solid part ratio, and the average non-solid part ratio at a position where the height is moved 0.10 mm from the base end part on the diagram toward the tip end part on the diagram is B, 0.10 × B ≥ 0.01 may be satisfied.

[0014] Also, in the average solid part aggregation diagram, the height from the base end part on the diagram to the position where the average solid part ratio is 0.30 may be 0.40 mm or less.

[0015] Also, in the average solid part aggregation diagram, a second interface parameter, which is a value obtained by dividing the outer peripheral surface length ratio by the height from the base end part on the diagram to the position where the average solid part ratio is 0.30, may be 4.00 or more.

Advantages of the Invention

[0016] According to the present invention, it is possible to provide an insert member capable of favorably controlling the thermal conductivity at the interface between the insert member and the motor case.

Brief Description of the Drawings

[0017]

Figure 1

Figure 2

Figure 3

Embodiments for Carrying Out the Invention

[0018] Hereinafter, embodiments of the present invention will be described with reference to the drawings. The configurations described in the following embodiments are not intended to limit the technical scope of the invention only to those, unless otherwise specified. Each configuration and their combinations, etc. in the following embodiments are examples, and additions, omissions, substitutions, and other changes of the configuration can be made as appropriate without departing from the gist of the present invention.

[0019] <Embodiment> [Structure] FIG. 1 is an overall view of an insert member 1 for a rotating electrical machine (hereinafter referred to as "insert member 1") according to an embodiment, and an enlarged view of a part of its outer peripheral surface. In the present embodiment, the direction along the central axis C of the insert member 1 is defined as the axial direction, the direction orthogonal to the axial direction and directed from the central axis C toward the outer peripheral surface side of the insert member 1 is defined as the radial direction. Further, the direction around the central axis C along the outer peripheral surface of the insert member 1 is defined as the circumferential direction. Such axial direction, radial direction, and circumferential direction are merely directions for indicating the relative positional relationship of each element in the insert member 1.

[0020] The insert member 1 according to this embodiment is, for example, a cast iron material formed in a substantially cylindrical shape centered on the central axis C, and a plurality of convex portions 10 are formed on the outer peripheral surface (surface). Here, a portion that is recessed relative to the convex portion 10 is referred to as a "concave portion 13", and a structure including the convex portion 10 and the concave portion 13 is referred to as a "concavo-convex portion". The rotating electric machine to which the present invention is applied is, for example, a rotating electric machine used in an electric vehicle or the like. However, the rotating electric machine to which the present invention is applied is not limited to this. In this embodiment, the outer diameter OD of the insert member 1 is formed within the range of 150 mm to 300 mm, but it may be appropriately changed depending on the use. Further, the outer diameter OD is a value corresponding to the distance between two parallel planes when the insert member 1 is placed between two parallel planes and the tip portions 11 of the convex portions 10 on the outer peripheral surface of the insert member 1 are brought into contact with the two parallel planes, respectively. Here, half of the value obtained by subtracting the inner diameter ID from the outer diameter OD is defined as the thickness of the insert member 1. It is preferable that the thickness of the insert member 1 is 0.8% or more of the outer diameter OD of the insert member 1. When the thickness of the insert member 1 is less than 0.8% of the outer diameter OD, the strength is insufficient when integrating the insert member 1 and the motor case, and the risk of cracking in the insert member 1 increases. Further, since it is desirable that the weight of the insert member 1 is light, the thickness of the insert member 1 is preferably about less than 4% of the outer diameter OD.

[0021] The rotating electrical machine is composed of components such as a rotating shaft, a rotor, a stator, a motor case, and bearings. The motor case has a cylindrical portion hollowed out inside. The stator is generally formed of electromagnetic steel sheets or the like and is to be fitted to the inner peripheral portion of the cylindrical portion. The insert member 1 is to be disposed at the fitting portion of the motor case with the stator. Here, the insert member 1 is cast into the inner peripheral portion of the aluminum alloy motor case and used. Thereby, the motor case and the insert member 1 form a composite structure in which at least a part of the outer peripheral surface of the insert member 1 is covered with the aluminum alloy. Here, the stator fitted to the inner peripheral portion of the insert member 1 generates heat as the rotating electrical machine operates. However, by making the outer peripheral surface of the insert member 1 in an appropriate form, the thermal conductivity at the interface between the insert member 1 and the motor case can be well controlled, and the generated heat can be efficiently released to the motor case.

[0022] As described above, the material of the insert member 1 is preferably cast iron or the like having high thermal conductivity compared with steel, but is not particularly limited. Typically, considering thermal conductivity and workability, Flake graphite cast iron equivalent to JIS FC250 or the like can be used.

[0023] The uneven portions on the outer peripheral surface of the insert member 1 may be formed by a method of transferring the unevenness of the mold coating agent in the centrifugal casting method, a method of directly performing machining such as cutting on the outer peripheral surface of the insert member, a roughening treatment method, or a combination of these methods. Examples of the roughening treatment include surface treatments such as thermal spraying, cold spraying, and shot blasting. Examples of the thermal spraying material include aluminum alloy and the like, but it is not particularly limited. However, the above-described material of the insert member 1 and the forming method of the uneven portions are merely examples and are not particularly limited.

[0024] FIG. 2 is a cross-sectional view showing an example of a predetermined cross-section of the insert member 1 according to the embodiment. The predetermined cross-section in the present embodiment is one of the cut surfaces that appear one by one on both sides of the central axis C when the insert member 1 is cut into two parts along the axial direction by a virtual plane including the central axis C of the insert member 1. The length of the cut surface in the axial direction is equal to or greater than a length d1 described later. In FIG. 2, as an example of the predetermined cross-section, the A-A' cross-section in FIG. 1 is shown. Hereinafter, with reference to FIG. 2, the concavo-convex portions provided in the insert member 1 according to the present embodiment will be described.

[0025] The convex portion 10 in the concavo-convex portion is a part of the insert member 1 and is formed on the outer peripheral surface of the insert member 1. The convex portions 10 may be arranged in a discontinuous and irregular (random) manner in terms of arrangement position and arrangement density in the axial direction and the circumferential direction, or may be arranged continuously and regularly in terms of arrangement position and arrangement density. Further, the convex portion 10 has a tip portion 11 and a base end portion 12, and is formed so as to protrude from the base end portion 12 toward the outer side in the radial direction of the insert member 1 toward the tip portion 11. However, the shapes of the convex portion 10 and the concave portion 13 are not particularly limited.

[0026] Furthermore, on the outer peripheral surface of the insert member 1, processing such as limiting a part of the location where the plurality of convex portions 10 are formed or removing a part of the plurality of convex portions 10 may be performed. As a result, the plurality of convex portions 10 may be formed only in a partial region of the outer peripheral surface of the insert member 1.

[0027] The convex portion 10 may be formed by being cast while centrifugal force is applied by a centrifugal casting method. At this time, since the tip portion 11 of the convex portion 10 is formed based on the inner peripheral surface of the mold, if the inner peripheral surface of the mold is a perfect circle, the distances from the central axis C of the insert member 1 are substantially equal, whereas the distances of the base end portion 12 from the central axis C may be uneven. Therefore, the height of the convex portion 10 is measured with reference to the tip portion 11 in the process of deriving the average maximum height h1 of the uneven portions using the solid part aggregation diagram described later. However, the forming method of the convex portion 10 is not limited to this, and for example, it may be formed by performing machining such as cutting on the outer peripheral surface of the cylindrical member.

[0028] Also, the shape of the convex portion 10 is not particularly limited. The convex portion 10 may have, for example, a shape that continuously spirals, or may have a shape that continuously forms an annulus along the circumferential direction. For example, by directly performing machining such as cutting on the outer peripheral surface of the insert member 1, the convex portion 10 can be formed in a spiral shape or an annular shape. The shape of the convex portion 10 may be any shape that has an effect in the solid cutting test, thermal conductivity measurement, surface temperature simulation, and compactness evaluation described later.

[0029] On the outer peripheral surface of the insert member 1, the region where the uneven portions are formed may be partially limited. Also, the outer peripheral surface of the insert member 1 may have at least one of a region where the outer peripheral surface length ratio described later is less than 1.15 and a region where the first interface parameter described later is less than 1.30 in a part in the axial direction. At this time, uneven portions may or may not be formed in the region where the outer peripheral surface length ratio is less than 1.15 or the region where the first interface parameter is less than 1.30. Also, the region where the outer peripheral surface length ratio is less than 1.15 or the first The length in the axial direction of the region where the interface parameter is less than 1.30 is preferably less than 50% of the total length of the insert member 1, more preferably less than 30%, and even more preferably less than 10%. Also, the region where the outer peripheral surface length ratio is less than 1.15 or the region where the first interface parameter is less than 1.30 may be a partial region or the entire region in the circumferential direction on the outer peripheral surface of the insert member 1. By limiting the region where the outer peripheral surface length ratio is less than 1.15 or the region where the first interface parameter is less than 1.30 to a part of the outer peripheral surface, the location where heat easily transfers in the insert member 1 can be changed according to the heat generating part of the stator, and deformation of the insert member 1 and the motor case due to heat can be prevented.

[0030] Reference numeral 30 in FIG. 2 indicates the contour line (hereinafter referred to as "contour line 30") of the outer peripheral surface of the insert member 1 along the shape of the convex portion 10 and the concave portion 13 in the range of the length d1 (an example of the "predetermined axial length" in the present invention) on a predetermined cut surface. Also, reference numeral 40 indicates the inner peripheral surface (hereinafter referred to as "inner peripheral surface 40") of the insert member 1. Since the insert member 1 is formed in a cylindrical shape, in FIG. 2, the inner peripheral surface 40 is formed as a straight line along the axial direction.

[0031] [Outer peripheral surface length ratio] The outer peripheral surface length ratio is the value obtained by dividing the length of the contour line 30 in the range of the length d1 by the length d1. When the value of the average maximum height h1 of the uneven portion is the same, it is expected that the higher the value of the outer peripheral surface length ratio, the better the thermal conductivity. At this time, the outer peripheral surface length ratio is preferably 1.15 or more, and more preferably 1.30 or more. Further, the value of the outer peripheral surface length ratio can be easily increased by increasing the value of the average maximum height h1 of the uneven portion and increasing the length of the contour line 30. However, if the average maximum height h1 of the uneven portion becomes excessive, the volume occupied by the insert member 1 in the vicinity of the interface between the insert member 1 and the motor case increases, so that the thermal resistance of conduction increases and the thermal conductivity at the interface may be impaired. Therefore, it is preferable that the outer peripheral surface length ratio is 3.00 or less. By setting the outer peripheral surface length ratio within such a range and preventing the average maximum height h1 of the uneven portion from becoming excessive, excellent thermal conductivity can be provided at the interface between the insert member 1 and the motor case. Further, since the average maximum height h1 of the uneven portion does not become too small, peeling between the insert member 1 and the motor case can be suppressed. The outer peripheral surface length ratio is measured at a plurality of cut surfaces, specifically six cut surfaces, in one insert member 1, and the outer peripheral surface length ratio is obtained as the average value thereof.

[0032] [Solid portion ratio] The convex portion 10 of the insert member 1 defines a solid portion region 21 and a non-solid portion region 22. As shown in FIG. 2, the solid portion region 21 and the non-solid portion region 22 are specified depending on whether or not the line segment 20 having the length d1 overlaps the convex portion 10 when the line segment 20 is superimposed on a predetermined cut surface. More specifically, in the range of the length d1, the region where the line segment 20 overlaps the convex portion 10 is defined as the solid portion region 21, and the region where the line segment 20 does not overlap the convex portion 10 is defined as the non-solid portion region 22. The line segment 20 is a virtual line segment parallel to the inner peripheral surface 40 (that is, parallel to the central axis C) on a predetermined cut surface, and is a line segment provided for convenience in specifying the solid portion region 21 and the non-solid portion region 22.

[0033] The solid part ratio is a value indicating the ratio of the area where the solid part region 21 is formed within the range of the length d1. By moving the line segment 20 along the direction of the arrow A20 in FIG. 2 (from the tip end portion 11 side to the base end portion 12 side in the radial direction) at a predetermined pitch, the length of the solid part region 21 at the measurement height, which is the distance in the radial direction from the tip end portion 11, can be obtained at each measurement point. At that time, the ratio of the total length of the solid part region 21 to the length d1 at an arbitrary measurement height is referred to as the "solid part ratio". The same operation is performed on a plurality of predetermined cross-sections, and the solid part ratios of the convex portions 10 at each cross-section are aggregated, and by averaging the solid part ratios at the measurement heights of each measurement point, the average solid part ratio, which is the average value of the solid part ratios of each measurement point based on a plurality of predetermined cross-sections at the arbitrary measurement height, can be obtained. The average solid part ratio, which is the average value of the solid part ratios of each measurement point based on a plurality of predetermined cross-sections at the arbitrary measurement height, can be obtained by averaging the solid part ratios at the measurement heights of each measurement point.

[0034] [Solid Part Aggregation Diagram] As shown in FIG. 2, the line segment 20 is moved toward the base end portion 12 side of the insert member 1 (the line segment 20 is moved along the direction of arrow A20) at a predetermined pitch, and the acquisition of the solid portion ratio is repeated until the solid portion ratio becomes 1.00. By plotting the obtained solid portion ratios on a graph, it is possible to graphically represent one shape that aggregates the shapes of the plurality of convex portions 10 appearing on a predetermined cut surface. This is referred to as a "solid portion aggregation diagram". The solid portion aggregation diagram is a graph that represents the measured height, which is the distance from the tip portion 11 in the height direction of the concavo-convex portion, on the vertical axis, and represents the solid portion ratio on the horizontal axis. Further, by performing the operation of obtaining the solid portion ratio at a plurality of predetermined cut surfaces and creating an average solid portion aggregation diagram in which the average solid portion ratios obtained by the plurality of predetermined cut surfaces are sequentially plotted, it is possible to grasp the formation state of the convex portions 10 in the insert member 1 on average. At this time, at any of the predetermined cut surfaces, the reference point in the height direction is the "tip portion 11 of the most protruding convex portion 10 among the plurality of convex portions 10 within the range of the length d1", and the pitch at which the line segment 20 is moved is also the same pitch. Thereby, the measured height can be uniquely determined at a plurality of predetermined cut surfaces. FIG. 3 shows an average solid portion aggregation diagram in which, as an example of the insert member 1 according to the present embodiment, the predetermined pitch is 0.05 mm, the length d1 is 14.7 mm, and the average solid portion ratios intermittently obtained from six predetermined cut surfaces of a certain sample are sequentially plotted.

[0035] The average maximum height h1 of the uneven portion is the absolute value of the value from the tip on the drawing to the base end on the vertical axis of the average solid portion aggregation diagram. The tip on the drawing corresponds to "the tip 11 of the most protruding convex portion 10 among the plurality of convex portions 10 within the range of the length d1" in the solid portion aggregation diagram. The measured height at the tip on the drawing is 0 mm, and the solid portion ratio is 0. The base end on the drawing is, in the solid portion aggregation diagram, "the position where the solid portion ratio first exceeds 0.98 when plotted in order from the tip 11 side to the base end 12 side", and in the average solid portion aggregation diagram, "the position where the average solid portion ratio first exceeds 0.98 when plotted in order from the tip 11 side to the base end 12 side". Note that since the solid portion ratio at each measurement point of the solid portion aggregation diagram is measured from the tip 11 side of the convex portion 10 located above toward the central axis C side located below, the measured height at each measurement point is displayed as a negative value. The same applies to the average solid portion aggregation diagram obtained from a plurality of solid portion aggregation diagrams, but the actual height of the uneven portion and the average maximum height h1 of the uneven portion are the absolute values of the values on the vertical axis of the average solid portion aggregation diagram, and the average maximum height h1 is the distance from the base end on the drawing to the tip on the drawing. Also, the points obtained by connecting each measurement point plotted on the average solid portion aggregation diagram with a line are referred to as the "average solid portion curve".

[0036] The length d1 of the line segment 20, which is a predetermined axial length, shall be 14.7 mm in principle, but may be appropriately changed in view of the sizes of the convex portions 10 and concave portions 13 of the measurement sample.

[0037] [Measurement method] [Preparation of measurement sample] The following describes a method for measuring the length of the contour line 30 and the solid portion ratio. First, a method for preparing a measurement sample will be described. The insert member 1 that includes the central axis C and is cut in the direction along the axial direction is further cut at a cross-section perpendicular to the axial direction so as to have a size that allows resin embedding and polishing, and resin embedding is performed so that all cross-sections for measuring the length of the contour line 30 and the solid portion ratio become polished surfaces. After the resin has solidified, the sample is polished using waterproof emery paper in running water. At this time, the grit numbers of the waterproof emery paper are changed in the order of #220, #400, #800, #1000, and #1500. When polishing is completed, the length of the contour line 30 and the solid portion ratio are measured. The observation surface after polishing is equivalent to a predetermined cut surface.

[0038] [Method for Measuring the Outer Peripheral Surface Length Ratio] In this embodiment, a digital microscope RX-100 manufactured by Highrox Co., Ltd. was used to measure the length of the contour line 30. The objective lens magnification during measurement was set to 20 times or 40 times. When the average maximum height h1 of the uneven portion is large, for example, when it exceeds 0.30 mm, 20 times magnification is used. In the case of the equipment used this time, when the objective lens magnification is 20 times, the length of the horizontal axis of the monitor is 14.7 mm, which is defined as the length d1. After setting the measurement sample after polishing, the measurement sample is set so that the inner peripheral surface 40 of the insert member 1 is parallel to the horizontal axis of the grid displayed on the observation monitor, and then the measurement sample is translated to a position where the outer peripheral surface can be observed. Using the "Automatic Area" tool in the software attached to the microscope, when the insert member 1 portion on the monitor is clicked to adjust the gradation density, the area and perimeter of the insert member 1 portion can be automatically measured due to the gradation density difference between the insert member 1 and the resin used for embedding. At this time, the gradation density is set to a value at which the insert member 1 is selected without excess or deficiency. Since the perimeter to be measured is the entire perimeter of the insert member 1 on the monitor, the length corresponding to the portion other than the contour line 30 of the insert member 1 is obtained and subtracted from the measured total perimeter. The length of the contour line 30 is obtained in this way. At this time, the length of the portion other than the contour line 30 can be obtained using the "Automatic Width" tool attached to the microscope. By dividing the length of the contour line 30 obtained in this way by the length d1, the outer peripheral surface length ratio can be obtained.

[0039] [Method for Measuring the Ratio of the Solid Portion] For the measurement of the solid part ratio, a digital microscope RX-100 manufactured by Highrox Co., Ltd. was used. The objective lens magnification during measurement was 20 times or 50 times. When the average maximum height h1 of the uneven part is large, for example, when it is 0.20 mm or more, 20 times magnification was used. The grid and automatic width tool by the software attached to the microscope were used. The measurement sample after polishing was set so that the inner peripheral surface 40 of the insert member 1 was parallel to the horizontal axis of the grid displayed on the observation monitor. Then, the observation sample was translated to a position where the outer peripheral surface could be observed. Next, using the automatic width tool, the measurement of the measurement sample in the horizontal axis direction was performed. Since the measurement by the automatic width tool uses automatic measurement using gradation density, the gradation density was adjusted each time so that the automatic identification of the insert member area corresponding to the solid part area 21 and the resin area corresponding to the non-solid part area 22 would be appropriate, and it was moved at a predetermined pitch to measure the length of the solid part area 21 at an arbitrary measurement height. The line segment 20 in this embodiment indicates the measurement position of the automatic width tool. By moving the line segment 20 along the radial direction of the insert member 1 from the tip end portion 11 side toward the base end portion 12 side at a predetermined pitch, the axial length of the solid part area 21 at an arbitrary measurement height from the tip end portion 11 can be measured. At this time, the line segment 20 was moved from the tip end portion 11 of the convex portion 10 that protrudes most within the range of the length d1 in all cross-sections toward the base end portion 12 side at a predetermined pitch of 0.05 mm or 0.025 mm for measurement. When using 50 times magnification for the objective lens, the predetermined pitch may be 0.025 mm.

[0040] In FIG. 2, the case where the line segment 20 is at the position 20a and the case where it is at the position 20b are illustrated. The position 20a is the position of the tip 11 of the convex portion 10 that protrudes most within the range of the length d1. When the line segment 20 is at the measured height shown at the position 20a, the line segment 20 overlaps with the tip 11 of the convex portion 10. Based on this, the line segment 20 is moved at a predetermined pitch in the direction indicated by the arrow A20 (toward the base end portion 12 side). The position 20b is an example of the measured height when the movement of the line segment 20 is repeated any number of times at a predetermined pitch. When the line segment 20 is at the measured height shown at the position 20b, it can be said that the insert member 1 defines the solid portion region 21 indicated by the broken line and the non-solid portion region 22 indicated by the solid line in the line segment 20. The line segment 20 is moved along the arrow A20, and from the position where the solid portion ratio described later first exceeds 0.98, the line segment 20 is further moved along the arrow A20. When all of the range of the length d1 in the line segment 20 becomes the solid portion region 21 (that is, when the solid portion ratio becomes 1.00), the measurement is terminated.

[0041] [Non-solid portion ratio] The non-solid portion ratio is, in the solid portion aggregation diagram, [Non-solid portion ratio at any measured height]=[Solid portion ratio of the base end portion on the drawing]-[Solid portion ratio at any measured height] is a value that satisfies the following relationship. Also, in the average solid portion aggregation diagram, [Average non-solid portion ratio at any measured height]=[Average solid portion ratio of the base end portion on the drawing]-[Average solid portion ratio at any measured height] the following relationship holds.

[0042] [Parameters of the average solid portion aggregation diagram] In the average solid part aggregation diagram, it is preferable to form the convex part 10 and the concave part 13 such that the average maximum height h1 of the uneven part is in the range of 0.15 mm or more and 1.50 mm or less. More preferably, the average maximum height h1 of the uneven part is in the range of 0.20 mm or more and 1.00 mm or less. At this time, by increasing the average maximum height h1 of the uneven part, the length of the contour line 30 can be increased. However, if the average maximum height h1 of the uneven part becomes excessive, the volume occupied by the convex part 10 increases near the interface between the insert member 1 and the motor case, and the thermal resistance of conduction increases, so there is a risk that the thermal conductivity will be impaired. On the other hand, by setting the average maximum height h1 of the uneven part to 1.50 mm or less and increasing the length of the contour line 30, that is, by increasing the interface length ratio, it helps the heat conductivity from the insert member 1 to the motor case and the heat dissipation from the motor case.

[0043] Also, by setting the average maximum height h1 of the uneven part to 1.50 mm or less, weight reduction and downsizing of the insert member 1 can be achieved. However, if the average maximum height h1 of the uneven part is too small, the bonding force between the insert member 1 and the motor case is insufficient, and there is a risk that the insert member 1 and the motor case will peel off. Generally, the greater the bonding force between the insert member 1 and the motor case, the better the thermal conductivity. Therefore, in order to maintain the bonding force between the insert member 1 and the motor case, it is preferable to set the average maximum height h1 of the uneven part to 0.15 mm or more. This makes it easier to suppress the peeling of the insert member 1 from the motor case.

[0044] Here, in the average solid part aggregation diagram, the average solid part ratio at the position where the height is moved 0.10 mm from the base end on the drawing to the tip end side on the drawing is referred to as the "first average solid part ratio", and the average non-solid part ratio obtained based on the first average solid part ratio is referred to as the "first average non-solid part ratio". Let the value of the first average solid part ratio be A and the value of the first average non-solid part ratio be B. At this time, the value obtained by dividing the outer peripheral surface length ratio by A is, for convenience, referred to as the "first interface parameter". The first interface parameter helps to grasp the shape near the base end 12 of the convex part 10. For example, a heating element such as a stator is arranged inside the insert member 1. At this time, the heat generated from the heating element is transmitted from near the base end 12 of the convex part 10 to the tip end 11 side where the motor case or the like is arranged. Therefore, in order to efficiently transmit the heat of the heating element to the motor case, the shape near the base end 12 in the insert member 1 is preferably as flat as possible. Therefore, the first average solid part ratio preferably has as small a value as possible. That is, the first interface parameter preferably has a large value. In FIG. 3, the first average solid part ratio at the position where the height is moved 0.10 mm from the base end on the drawing to the tip end side on the drawing is shown as A, and the first average non-solid part ratio at that position is shown as B.

[0045] Also, the value obtained by dividing the outer peripheral surface length ratio by the height from the base end on the drawing to the position where the average solid part ratio is 0.30 is, for convenience, referred to as the "second interface parameter". In FIG. 3, the "height from the base end on the drawing to the position where the average solid part ratio is 0.30" is indicated by h2. In other words, the height h2 is the "difference between the measured height of the base end on the drawing and the measured height of the position where the average solid part ratio becomes 0.30". Here, when there are a plurality of positions where the average solid part ratio becomes 0.30, the most base end on the drawing The position on the part side is the object of evaluation. That is, the height h2 is the height from the base end portion on the drawing to the position on the base end portion side on the drawing where the average solid portion ratio becomes 0.30. The second interface parameter can easily grasp the shape of the convex portion 10 of the insert member 1 from the base end portion on the drawing to the position where the average solid portion ratio is 0.30 based on the average solid portion total drawing. By using the above-mentioned first interface parameter and second interface parameter, the outer peripheral surface length ratio can be normalized at a certain position in the average solid portion total drawing, and it becomes easier to confirm the correlation between the shape of the uneven portion and the thermal conductivity.

[0046] The measured height at the position where the average solid portion ratio is 0.30 can be obtained based on two consecutive points in the average solid portion total drawing, namely, the point where the average solid portion ratio is less than 0.30 and the point where the average solid portion ratio exceeds 0.30. Specifically, it can be obtained from the function of the straight line connecting the point where the average solid portion ratio is less than 0.30 on the average solid portion total drawing and the point that is continuous with the said point and where the average solid portion ratio exceeds 0.30.

[0047] By arranging the shape of the uneven portion in the insert member 1 of the present invention based on the outer peripheral surface length ratio and the average solid portion total drawing and using the first interface parameter and the second interface parameter, it is possible to discriminate an insert member 1 that is more excellent in thermal conductivity at the interface between the insert member 1 and the motor case.

[0048] [Test / Simulation] The insert members 1 according to Examples 1 to 11 of the present invention and the insert members according to Comparative Examples 1 to 3 were evaluated by tests and simulations using samples. Specifically, for the insert members of the examples and comparative examples (hereinafter referred to as examples, etc.), measurements of various parameters, solid cutting tests, thermal conductivity measurements, and surface temperature simulations were performed.

[0049] [Measurement of Various Parameters] Various parameters of the insert member according to the examples and the like were measured. Table 1 shows the results of each measurement item of the insert member according to the examples and the like. In Measurement Item 1, the insert member in each example and the like was cut to obtain the outer peripheral surface length ratio. In Measurement Items 2 to 8, the respective values were obtained using the average solid part aggregation diagram in each example and the like. When creating the average solid part aggregation diagram in each example and the like, the predetermined pitch was set to 0.05 mm or 0.025 mm. Also, in the measurement of the outer peripheral surface length ratio, the predetermined axial length was set to 14.7 mm in Examples 1 to 3, 6 to 11, and Comparative Examples 1 to 3, and 7.35 mm in Examples 4 and 5. Further, in the measurement of the average solid part ratio, the predetermined axial length was set to 14.7 mm in Examples 1 to 3, 6 to 11, and Comparative Examples 1 and 3, and 5.57 mm in Examples 4 and 5 and Comparative Example 2. Note that the content in parentheses for each measurement item is the unit of use, and those without description are dimensionless numbers.

[0050] [1. Outer Peripheral Surface Length Ratio] As Measurement Item 1, the outer peripheral surface length ratio was measured. At this time, the outer peripheral surface length ratio was obtained by cutting and polishing the insert member in the examples and the like along the axial direction with a virtual plane including the central axis C, measuring the length of the contour line 30. Also, in order to secure a predetermined axial length for obtaining the contour line 30, the insert member was also cut in a direction perpendicular to the axial direction (radial direction). The cut surface thus obtained was observed with a microscope. The outer peripheral surface length ratio was obtained by cutting out arbitrary six predetermined cut surfaces from one insert member and obtaining the average value.

[0051] [2. Average Maximum Height h1 (mm) of the Concavo-Convex Portion] As Measurement Item 2, the average maximum height h1 of the concavo-convex portion was measured using the average solid part aggregation diagram in each example and the like. Regarding Comparative Example 1, since the numerical value of the average maximum height h1 of the concavo-convex portion is small, the measurement of other items was not performed.

[0052] [3. First Average Solid Part Ratio A] As measurement item 3, the first average solid part ratio A was obtained using the average solid part aggregation diagram in each example etc. As described above, the first average solid part ratio A is the average solid part ratio at the position where the height is moved 0.10 mm from the base end portion on the drawing toward the tip end portion side on the drawing.

[0053] [4. First interface parameter] As measurement item 4, the first interface parameter was obtained by dividing the outer peripheral surface length ratio obtained in measurement item 1 by the first average solid part ratio A obtained in measurement item 3.

[0054] [5. 0.10 / First average non-solid part ratio B (mm)] As measurement item 5, the slope of the straight line connecting the two points of the measurement position of the first average solid part ratio A and the base end portion on the drawing in the average solid part aggregation diagram of each example etc. (hereinafter referred to as the slope of the average solid part curve) was obtained. The first average non-solid part ratio B is obtained by subtracting the value of the first average solid part ratio A obtained in measurement item 3 from the average solid part ratio of the base end portion on the drawing in each example etc. By confirming the slope of the average solid part curve, it helps to grasp the shape in the vicinity of the base end portion of the convex part. The slope of the average solid part curve is obtained by [0.10 / first average non-solid part ratio B].

[0055] [6. 0.10 × First average non-solid part ratio B (mm)] As measurement item 6, in the average solid part aggregation diagram of each example etc., the area of a predetermined region was obtained as follows. Similar to measurement item 5, the first average non-solid part ratio B is obtained by subtracting the first average solid part ratio A obtained in measurement item 3 from the average solid part ratio of the base end portion on the drawing in each example etc. Here, the predetermined region is a rectangular region in the average solid part aggregation diagram where the height from the base end portion on the drawing is 0.10 mm and the width is the first average non-solid part ratio B, and is a region including the average solid part curve up to the position where the height is moved 0.10 mm from the base end portion on the drawing toward the tip end portion side on the drawing. The area of the predetermined region is obtained by [0.10 × first average non-solid part ratio B]. This helps to grasp the shape of the concave-convex part in the vicinity of the base end portion of the convex part.

[0056] [7. Height h2 (mm) from the base end portion on the drawing to the position where the average solid portion ratio is 0.30] As measurement item 7, the height h2, which is the height from the base end portion on the drawing to the position where the average solid portion ratio is 0.30 in each example, etc., was obtained. The smaller the height h2, the closer the shape from the base end portion on the drawing to the position where the average solid portion ratio is 0.30 in the insert member becomes to a flat shape.

[0057] [8. Second interface parameter (1 / mm)] As measurement item 8, the second interface parameter was obtained by dividing the outer peripheral surface length ratio obtained in measurement item 1 by the height h2 obtained in measurement item 7.

[0058] Table 1 shows the measurement results of various parameters measured as described above.

Table 1

[0059] [Solid cutting test] In the solid cutting test, in each example, etc., a composite body was produced in which an aluminum alloy was used as the outer member and the insert member was cast in the outer member. Here, the outer member means a member located on the outer side in the radial direction of the insert member, such as a motor case. Further, the composite body was cut, and a test piece of 20 mm × 20 mm was cut out. For each example, etc., the joinability between the insert member and the outer member was evaluated by determining the presence or absence of peeling between the insert member and the outer member when a plurality of test pieces were cut out. Specifically, six test pieces were cut out from each example, etc., and the presence or absence of peeling was determined. Table 2 shows the criteria for determination.

Table 2

[0060] [Thermal conductivity measurement] Among the test pieces used in the solid cutting test, test pieces for measuring thermal conductivity with a diameter of 10 mm and a thickness of 3 mm were prepared from those that did not peel off. Using the test pieces for measuring thermal conductivity, the thermal conductivity was measured by the laser flash method. At this time, while observing the side surface of the test piece for measuring thermal conductivity, it was adjusted so that the central part of the height of the uneven part was located at the central part of the thickness of the test piece for measuring thermal conductivity. For those in which the insert member and the outer member were peeled off when cutting out the test piece, the thermal conductivity was considered unmeasurable (0 W / m·K). For those that peeled off several times in multiple tests or those that did not peel off in multiple tests, the average value of those that did not peel off was obtained and shown in Table 6.

[0061] [Surface temperature simulation] In each example, etc., a model was created with the thickness of the insert member being 2 mm, the thickness of the composite part (the interface part between the insert member and the outer member) being 3 mm, and the thickness of the outer member being 2 mm, and the surface temperature of the outer member was simulated. At this time, assuming that the temperature of the inner peripheral surface of the insert member is 150 °C and the temperature of the fluid on the outer periphery of the outer member is 50 °C, and there is a fluid for cooling on the outer periphery of the outer member, the surface temperature of the outer member was obtained. Also, regarding the heat transfer from the surface of the outer member to the fluid, the heat transfer coefficient was 200 W / m 2 ·K. Based on the surface temperature of the outer member obtained by the simulation, the heat dissipation performance was evaluated according to the criteria shown in Table 3. At this time, the higher the surface temperature, the more efficiently the internal heat can be transferred, and it can be said that the heat dissipation performance is excellent.

Table 3

[0062] [Compactness evaluation] Based on the average maximum height h1 of the uneven part, which is the measurement item 2 in the measurement of the above various parameters, the compactness was evaluated according to the criteria shown in Table 4.

Table 4

[0063] In the comprehensive determination, evaluation was performed as shown in Table 5 based on the determination symbols for each measurement item.

Table 5

[0064] The results of the sample tests measured as described above and the comprehensive determination are shown in Table 6.

Table 6

[0065] From the results shown in Table 6, it was confirmed that in the comprehensive determination, all of Examples 1 to 11 were superior to any of Comparative Examples 1 to 3. Furthermore, it was confirmed that Examples 2, 3, 4, and 5 were particularly excellent. Furthermore, by comparing Examples 1 to 8, 10 with Comparative Examples 1 to 3, it was confirmed that by forming the uneven portions so that the first interface parameter is 1.30 or more and the second interface parameter is 4.00 or more, the thermal conductivity at the interface between the insert member and the motor case is increased.

[0066] Also, in Examples 4, 5, and 10, the outer peripheral surface of the insert member was subjected to roughening treatment by thermal spraying or cold spraying, and it was confirmed that the thermal conductivity was higher compared to other examples and the like.

[0067] Moreover, by comparing Examples 1 and 9 with other examples and the like, it was confirmed that even when the outer peripheral surface length ratio is large, if the average maximum height h1 of the uneven portions is relatively large as in Examples 1 and 9, the thermal conductivity does not increase. Also, it was confirmed that when the average maximum height h1 of the uneven portions is excessive as in Comparative Example 3, the thermal conductivity at the interface between the insert member and the motor case decreases.

[0068]

[0069] ​From the above results, it was confirmed that in Examples 4 and 5 where the value of the first average solid part ratio A is small and the value of the first interface parameter is large, the thermal conductivity is high. In Example 5 where the first interface parameter is the largest among the examples, the thermal conductivity at the interface between the insert member and the motor case was the largest.

[0070] From the above results, referring to Examples 1 to 11, the slope of the average solid part curve in the average solid part aggregation diagram is 0.10 / B ≦ 1.30 It was confirmed that it is preferable that. Also, referring to Examples 2 to 5, it was confirmed that when the slope of the average solid part curve is small, the thermal conductivity at the interface between the insert member and the motor case becomes high.

[0071] From the above results, referring to Examples 1 to 11, the area of the predetermined region in the average solid part aggregation diagram obtained in Measurement Item 6 is 0.10 × B ≧ 0.01 It was confirmed that it is preferable that. Also, referring to Examples 2 to 5, it was confirmed that when the area of the said predetermined region is large, the thermal conductivity at the interface between the insert member and the motor case becomes high.

[0072] From the above results, as in Comparative Examples 1 and 2, it was found that those with an outer peripheral surface length ratio of less than 1.15 cause the insert member and the outer member to peel off when cutting out the test piece. Also, as in Examples 6 to 8, since there were cases of peeling when the outer peripheral surface length ratio was greater than 1.15 and less than 1.30, it was confirmed that the outer peripheral surface length ratio is more preferably 1.30 or more.

[0073] From the above results, as in Examples 1 to 5, it was confirmed that when the height h2 is 0.40 mm or less, the thermal conductivity becomes high. Also, in Examples 6 to 8, although the height h2 is 0.40 mm or less, peeling was observed during cutting out of the test piece, and since the bonding property is not necessarily high, it was confirmed that the thermal conductivity becomes low.

[0074] [Operational Effects] By forming the uneven portions according to the present invention on the outer peripheral surface of the insert member 1, the heat generated by a stator or the like can be efficiently dissipated to the outside, and the thermal conductivity at the interface between the insert member 1 and the motor case can be improved.

[0075] The plurality of convex portions 10 are arranged on the outer peripheral surface of the insert member 1 such that adjacent convex portions 10 have an appropriate interval therebetween. Thereby, the casting material poured into the mold can also reach between the plurality of convex portions 10, and it becomes possible to suppress the voids generated between the motor case and the insert member 1, and the thermal conductivity at the interface between the motor case and the insert member 1 can be improved.

[0076] In the insert member 1 of the present invention, within the range of the length d1, the convex portions 10 and the concave portions 13 are formed so as to ensure the length of the contour line 30 without making the uneven portions excessively large. Therefore, the thermal conductivity at the interface between the insert member 1 and the motor case can be favorably controlled. Thereby, an increase in the thickness of the motor case leading to an increase in the size and mass of the motor case itself is suppressed, and while achieving weight reduction and downsizing of the rotating electrical machine, the thermal conductivity from the insert member 1 to the motor case and the heat dissipation performance of the rotating electrical machine itself can be improved.

[0077] As described above, the embodiments according to the present invention have been described, but each aspect disclosed in this specification can be combined with any other features disclosed in this specification.

Explanation of Reference Numerals

[0078] 1: Insert member for rotating electrical machine 10: Convex portion 13: Concave portion 20: Line segment 30: Contour line 40: Inner peripheral surface C: Central axis of insert member

Claims

1. A substantially cylindrical insert member cast into an aluminum alloy motor case of a rotating electrical machine, on the outer peripheral surface of the insert member, an uneven portion including a concave portion and a convex portion is formed, in a cut surface which is one of the cut surfaces that appear one by one on both sides of the central axis when the insert member is cut into two along the axial direction by a virtual plane including the central axis of the insert member, when a line along the contour of the outer peripheral surface including the contour of the uneven portion in a range of a predetermined axial length is defined as a contour line, an outer peripheral surface length ratio which is a value obtained by dividing the length of the contour line by the predetermined axial length is 1.15 or more and 3.00 or less, An insert member for a rotating electrical machine.

2. In the range of the predetermined axial length, when a line segment parallel to the inner peripheral surface of the insert member is overlapped with the cut surface, a solid portion region where the insert member overlaps the line segment on the line segment and a non-solid portion region where the insert member does not overlap the line segment on the line segment are defined, on the line segment, a value indicating the ratio of the solid portion region in the range of the predetermined axial length is defined as a solid portion ratio, in the cut surface of the insert member, the solid portion ratio values of each measurement point obtained by moving the line segment along the height direction of the uneven portion at a predetermined pitch from the tip of the convex portion that protrudes most in the uneven portion toward the base end side of the convex portion are plotted in order, a graph in which the solid portion ratio is represented on the horizontal axis and the distance from the tip in the height direction is represented as the measurement height on the vertical axis is defined as a solid portion aggregation graph, a solid portion aggregation graph in which the average of the solid portion ratios at each measurement point based on a plurality of the cut surfaces is defined as an average solid portion ratio and the average solid portion ratios are plotted in order is defined as an average solid portion aggregation graph, in the average solid portion aggregation graph, a position where the average solid portion ratio is 0 is defined as the tip on the graph, Taking the position where the average solid part ratio, which is plotted in order from the tip side toward the base end side, first exceeds 0.98 as the base end on the drawing, when the distance from the tip on the drawing to the base end on the drawing is defined as the average maximum height of the uneven portion, the average maximum height of the uneven portion is 0.15 mm or more and 1.50 mm or less, The insert member for a rotating electrical machine according to claim 1.

3. When the average solid part ratio at a position where the height is moved 0.10 mm from the base end on the drawing toward the tip side on the drawing is defined as A, and the value obtained by dividing the outer peripheral surface length ratio by A is defined as the first interface parameter, the first interface parameter is 1.30 or more, The insert member for a rotating electrical machine according to claim 2.

4. When half of the value obtained by subtracting the inner diameter from the outer diameter of the insert member is defined as the thickness of the insert member, the thickness of the insert member is 0.8% or more of the outer diameter of the insert member, The insert member for a rotating electrical machine according to claim 1.

5. The outer peripheral surface is subjected to a roughening treatment. The insert member for a rotating electrical machine according to claim 1.

6. The outer peripheral surface of the insert member has at least one of a region where the outer peripheral surface length ratio is less than 1.15 and a region where the first interface parameter is less than 1.30 in a part in the axial direction. The insert member for a rotating electrical machine according to claim 3.

7. In the average solid part aggregation diagram, when the value obtained by subtracting the average solid part ratio at a certain measurement height from the average solid part ratio at the base end on the drawing is defined as the average non-solid part ratio, and the average non-solid part ratio at a position where the height is moved 0.10 mm from the base end on the drawing toward the tip side on the drawing is defined as B, 0.10 / B ≤ 1.30 The insert member for a rotating electrical machine according to claim 3.

8. In the average solid part aggregation diagram, When the value obtained by subtracting the average solid part ratio at a certain measurement height from the average solid part ratio at the base end part on the diagram is defined as the average non-solid part ratio, and B is the average non-solid part ratio at the position where the height is moved 0.10 mm from the base end part on the diagram toward the tip end part side on the diagram, 0.10 × B ≥ 0.01 The insert member for a rotating electrical machine according to claim 3.

9. In the average solid part aggregation diagram, The height from the base end part on the diagram to the position where the average solid part ratio is 0.30 is 0.40 mm or less. The insert member for a rotating electrical machine according to claim 3.

10. In the average solid part aggregation diagram, A second interface parameter, which is the value obtained by dividing the outer peripheral surface length ratio by the height from the base end part on the diagram to the position where the average solid part ratio is 0.30, is 4.00 or more. The insert member for a rotating electrical machine according to claim 3.

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