Insert member for rotary electric 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 technology]

[0002] In general, aluminum alloys are often used as structural members of motor cases for rotating electrical machines. In addition, in the motor case, a high-strength member made of an iron-based material and formed into a substantially cylindrical shape may be used as an insert member in the portion where the stator is disposed to supplement the 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] JP 2001-169500 ​​A [Patent Document 2] Patent No. 6655560 Summary of the Invention [Problem to be solved by the invention]

[0004] However, insert members made of iron-based materials have poorer thermal conductivity than aluminum alloys, which are commonly used as structural members for motor cases. Therefore, while the unevenness on the outer peripheral surface of the insert member increases the bonding strength with the motor case, it is not possible to efficiently dissipate heat generated by heating elements such as the stator to the outside, which could lead to a decrease in motor output and a decrease in the magnetic force of the magnets used in the motor.

[0005] The technology of the present invention has been made in consideration of the above-mentioned situation, and its object is to provide an insert member that can effectively control 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 employs the following configuration: An insert member for a rotating electric machine as one aspect of the technology of the present invention is a substantially cylindrical insert member that is cast into an aluminum alloy motor case of a rotating electric machine, the insert member has an outer peripheral surface formed with an uneven portion including a recess and a protrusion, and when the insert member is cut into two parts along the axial direction by a virtual plane including a central axis of the insert member, and when a line along the contour of the outer peripheral surface including the contour of the uneven portion within a range of a predetermined axial length is taken 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.

[0007] Furthermore, the insert member is defined, within the predetermined axial length range, as a line segment parallel to an inner peripheral surface of the insert member overlapping the line segment, and a non-substantial portion region where the insert member does not overlap the line segment when the line segment is overlapped with the entire cross section, and a value indicating the proportion of the solid portion region within the predetermined axial length range on the line segment is defined as a solid portion ratio. The line segment is moved at a predetermined pitch along the height direction of the uneven portion from the tip end of the most protruding convex portion in the uneven portion toward the base end side of the convex portion, and values ​​of the solid portion ratio at each measurement point are plotted in order, and the solid portion ratio is represented on the horizontal axis. a diagram in which the vertical axis represents the distance from the tip end in the height direction as a measured height is defined as a solid part summary diagram, an average of the solid part ratios at the measurement points based on a plurality of the cross sections is defined as an average solid part ratio, and the solid part summary diagram in which the average solid part ratios are plotted in sequence is defined as an average solid part summary diagram, a position in the average solid part summary diagram where the average solid part ratio is 0 is defined as a tip end on the diagram, a position where the average solid part ratio, plotted in sequence from the tip end side to the base end side, first exceeds 0.98 is defined as a base end on the diagram, and the distance from the tip end on the diagram to the base end on the diagram is defined as an average maximum height of the uneven portions, the average maximum height of the uneven portions may be 0.15 mm or more and 1.50 mm or less.

[0008] In addition, when the average solid portion ratio at a position moved 0.10 mm in height from the base end on the figure toward the tip end on the figure is defined as A, and the value obtained by dividing the outer circumferential surface length ratio by A is defined as a first interface parameter, the first interface parameter may be 1.30 or more.

[0009] Furthermore, when the thickness of the insert member is defined as half the value obtained by subtracting the inner diameter from the outer diameter 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] The outer peripheral surface may be subjected to a roughening treatment.

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

[0012] Furthermore, in the average solid part summary diagram, an average non-solid part ratio is defined as a 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 diagram, and the average non-solid part ratio at a position moved 0.10 mm in height from the base end on the diagram toward the tip end on the diagram is defined as B, and 0.10 / B≦1.30 may be satisfied.

[0013] Furthermore, in the average solid part summary diagram, an average non-solid part ratio may be defined as a 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 diagram, and the average non-solid part ratio at a position moved 0.10 mm in height from the base end on the diagram toward the tip end on the diagram, and B may satisfy 0.10×B≧0.01.

[0014] In addition, in the average solid portion summary diagram, the height from the base end to a position on the diagram where the average solid portion ratio is 0.30 may be 0.40 mm or less.

[0015] In addition, a second interface parameter, which is a value obtained by dividing the outer circumferential surface length ratio by a height from the base end to a position on the average solid portion summary diagram where the average solid portion ratio is 0.30, may be 4.00 or more. Effect of the Invention

[0016] According to the present invention, it is possible to provide an insert member that can satisfactorily control the thermal conductivity at the interface between the insert member and the motor case. [Brief description of the drawings]

[0017] [Figure 1] FIG. 1 is an overall view of an insert member for a rotating electrical machine according to an embodiment, and an enlarged view of a part of the outer circumferential surface thereof. [Diagram 2] FIG. 2 is a cross-sectional view showing an example of a predetermined cut surface of the insert member for a rotating electric machine according to the embodiment. [Diagram 3] FIG. 3 is an average solid portion summary diagram illustrating the relationship between the measurement height and the average solid portion ratio of the insert member for a rotating electrical machine according to the embodiment. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[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 unless otherwise specified. Each configuration and combination thereof in the following embodiments is merely an example, and addition, omission, substitution, and other modifications of the configurations are possible as appropriate within the scope of the gist of the present invention.

[0019] <Embodiment> [structure] 1 is an overall view of an insert member 1 for a rotating electric machine according to an embodiment (hereinafter referred to as "insert member 1"), and an enlarged view of a part of its outer circumferential surface. In this embodiment, the direction along the central axis C of the insert member 1 is defined as the axial direction, and the direction perpendicular to the axial direction from the central axis C toward the outer circumferential surface of the insert member 1 is defined as the radial direction. The direction around the central axis C along the outer circumferential surface of the insert member 1 is defined as the circumferential direction. Such axial, radial, and circumferential directions 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 protruding portions 10 are formed on the outer circumferential surface (surface). Here, the portion that is recessed relative to the protruding portion 10 is referred to as a "recess 13", and the structure including the protruding portion 10 and the recessed portion 13 is referred to as an "uneven 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 a range of 150 mm to 300 mm, but may be appropriately changed depending on the use. In addition, the outer diameter OD is a value equivalent to the distance between two parallel planes when the insert member 1 is placed between two parallel planes and the tip portion 11 of the protruding portion 10 on the outer circumferential surface of the insert member 1 is brought into contact with each of the two parallel planes. Here, the thickness of the insert member 1 is half the value obtained by subtracting the inner diameter ID from the outer diameter OD. The thickness of the insert member 1 is preferably 0.8% or more of the outer diameter OD of the insert member 1. If the thickness of the insert member 1 is less than 0.8% of the outer diameter OD, the strength will be insufficient when integrating the insert member 1 with the motor case, increasing the risk of cracking the insert member 1. In addition, since it is desirable for the insert member 1 to be lightweight, the thickness of the insert member 1 is preferably less than about 4% of the outer diameter OD.

[0021] The rotating electric machine includes, for example, a rotating shaft, a rotor, a stator, a motor case, bearings, and other components. The motor case has a cylindrical portion with the inside hollowed out in a cylindrical shape. The stator is generally formed of an electromagnetic steel sheet or the like, and is fitted into the inner periphery of the cylindrical portion. The insert member 1 is disposed in the fitting portion of the motor case with the stator. Here, the insert member 1 is used by being cast into the inner periphery of the motor case made of an aluminum alloy. As a result, the motor case and the insert member 1 become a composite structure in which at least a part of the outer periphery of the insert member 1 is covered with an aluminum alloy. Here, the stator fitted into the inner periphery of the insert member 1 generates heat as the rotating electric machine operates, but by forming the outer periphery of the insert member 1 into an appropriate shape, 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] The material of the insert member 1 is preferably cast iron, which has a higher thermal conductivity than steel, but is not limited thereto. Typically, a material that takes into consideration thermal conductivity and workability is used. Flake graphite cast iron equivalent to JIS FC250 can be used.

[0023] The uneven portion on the outer peripheral surface of the insert member 1 may be formed by a method of transferring the unevenness of a mold wash in a centrifugal casting method, a method of directly subjecting the outer peripheral surface of the insert member to machining such as cutting, a method of subjecting the outer peripheral surface to a roughening treatment, 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 spray material include, but are not limited to, aluminum alloys. However, the material of the insert member 1 and the method of forming the uneven portion described above are merely examples and are not particularly limited.

[0024] FIG. 2 is a cross-sectional view showing an example of a predetermined cut surface of the insert member 1 according to the embodiment. The predetermined cut surface in this embodiment is a cross section that is one of the cut surfaces that appear 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 cross section in the axial direction is equal to or longer than the length d1 described below. In FIG. 2, the A-A' cross section in FIG. 1 is shown as an example of the predetermined cut surface. Below, the uneven portion provided in the insert member 1 according to this embodiment will be described with reference to FIG. 2.

[0025] The convex portions 10 in the uneven portion are part of the insert member 1, and are formed on the outer peripheral surface of the insert member 1. The convex portions 10 may be arranged in a plurality of positions and density that are discontinuous and irregular (random) in the axial and circumferential directions, or may be arranged in a plurality of positions and density that are continuous and regular. The convex portions 10 have a tip portion 11 and a base portion 12, and are formed so as to protrude from the base portion 12 to the tip portion 11 toward the outside in the radial direction of the insert member 1. However, the shapes of the convex portions 10 and the concave portions 13 are not particularly limited.

[0026] Furthermore, the locations where the multiple protrusions 10 are formed on the outer peripheral surface of the insert member 1 may be limited to a certain area, or a process may be performed to remove some of the multiple protrusions 10. As a result, the multiple protrusions 10 may be formed only in a certain area of ​​the outer peripheral surface of the insert member 1.

[0027] The protrusion 10 may be formed by casting while applying centrifugal force by centrifugal casting. In this case, the tip 11 of the protrusion 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 distance from the central axis C of the insert member 1 will be almost equal, whereas the distance from the central axis C of the base end 12 may be uneven. Therefore, the height of the protrusion 10 is measured based on the tip 11 in the process of deriving the average maximum height h1 of the uneven portion using the substantial part summary diagram described later. However, the method of forming the protrusion 10 is not limited to this, and the protrusion 10 may be formed by performing machining such as cutting on the outer peripheral surface of a cylindrical member, for example.

[0028] The shape of the protrusion 10 is not particularly limited. The protrusion 10 may have, for example, a spirally continuous shape, or a circularly continuous shape along the circumferential direction. For example, the protrusion 10 can be formed into a spiral or circular shape by directly performing machining such as cutting on the outer circumferential surface of the insert member 1. The shape of the protrusion 10 may be any shape that is effective in the actual cutting test, thermal conductivity measurement, surface temperature simulation, and compactness evaluation described below.

[0029] The region in which the unevenness is formed on the outer peripheral surface of the insert member 1 may be limited to a part. Also, the outer peripheral surface of the insert member 1 may have at least one of a region in which the outer peripheral surface length ratio described below is less than 1.15 and a region in which the first interface parameter described below is less than 1.30 in a part in the axial direction. In this case, the unevenness may be formed in the region in which the outer peripheral surface length ratio is less than 1.15 or the region in which the first interface parameter is less than 1.30, or the unevenness may not be formed. Also, in the region in which the outer peripheral surface length ratio is less than 1.15 or the region in which the first interface parameter is less than 1.30, the unevenness may be formed in the region in which the outer peripheral surface length ratio is less than 1.15 and the first interface parameter is less than 1.30. The length in the axial direction of the region where the first interface parameter is less than 1.30 is preferably less than 50%, more preferably less than 30%, and even more preferably less than 10% of the total length of the insert member 1. The region where the outer peripheral surface length ratio is less than 1.15 and the region where the first interface parameter is less than 1.30 may be a partial region in the circumferential direction on the outer peripheral surface of the insert member 1, or may be the entire region in the circumferential direction. By limiting the region where the outer peripheral surface length ratio is less than 1.15 and the region where the first interface parameter is less than 1.30 to a portion of the outer peripheral surface, the location of the insert member 1 where heat is easily transferred can be changed according to the heat generating portion 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 a contour line (hereinafter referred to as "contour line 30") of the outer peripheral surface of the insert member 1 that follows the shapes of the protrusions 10 and recesses 13 within a range of length d1 (an example of "predetermined axial length" in the present invention) in a predetermined cross section. Reference numeral 40 indicates an 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 circumference length ratio] The outer peripheral surface length ratio is a 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 greater the value of the outer peripheral surface length ratio, the better the thermal conductivity. In this case, the outer peripheral surface length ratio is preferably 1.15 or more, and more preferably 1.30 or more. 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, but if the average maximum height h1 of the uneven portion becomes excessive, the volume occupied by the insert member 1 near the interface between the insert member 1 and the motor case increases, so that the thermal resistance of conduction increases, and there is a risk of impairing the thermal conductivity at the interface. Therefore, it is preferable to set the outer peripheral surface length ratio to 3.00 or less. By setting the outer peripheral surface length ratio in such a range and preventing the average maximum height h1 of the uneven portion from becoming excessive, it is possible to provide excellent thermal conductivity at the interface between the insert member 1 and the motor case. Furthermore, since the average maximum height h1 of the uneven portion is not too small, it is possible to suppress separation between the insert member 1 and the motor case. The outer peripheral surface length ratio is measured on multiple cut surfaces, specifically, on six cut surfaces, of one insert member 1, and the outer peripheral surface length ratio is calculated as the average value.

[0032] [Body ratio] A substantial region 21 and a non-substantial region 22 are defined by the convex portion 10 of the insert member 1. As shown in FIG. 2, the substantial region 21 and the non-substantial region 22 are identified based on whether a line segment 20 having a length d1 overlaps with the convex portion 10 when the line segment 20 is superimposed on a predetermined cut surface. More specifically, within the range of length d1, the region where the line segment 20 overlaps with the convex portion 10 is defined as the substantial region 21, and the region where the line segment 20 does not overlap with the convex portion 10 is defined as the non-substantial region 22. The line segment 20 is a virtual line segment parallel to the inner peripheral surface 40 (i.e., parallel to the central axis C) on the predetermined cut surface, and is a line segment provided for the sake of convenience in order to identify the substantial region 21 and the non-substantial region 22.

[0033] The solid portion ratio is a value indicating the proportion of the solid portion region 21 formed within the range of length d1. By moving the line segment 20 at a specified pitch along the direction of the arrow A20 in FIG. 2 (from the tip end 11 side to the base end 12 side in the radial direction), the length of the solid portion region 21 at each measurement height, which is the radial distance from the tip end 11, can be obtained. In this case, the ratio of the total length of the solid portion region 21 to the length d1 at any measurement height is referred to as the "solid portion ratio." The same operation is performed on multiple specified cut surfaces, and the solid portion ratios of the convex portion 10 on each cut surface are aggregated, and the solid portion ratio at the measurement height of each measurement point is obtained. By averaging the ratios, an average solid portion ratio can be obtained, which is the average value of the solid portion ratios of the measurement points based on a plurality of predetermined cut sections at the arbitrary measurement height.

[0034] [Substance summary chart] As shown in FIG. 2, the line segment 20 is moved toward the base end 12 of the insert member 1 (the line segment 20 is moved in the direction of the arrow A20) at a predetermined pitch, and the acquisition of the solid part ratio is repeated until the solid part ratio becomes 1.00. The acquired solid part ratio is plotted on a graph, and the shapes of the multiple convex parts 10 appearing on a predetermined cut surface can be graphed as one shape that aggregates them. This is called a "solid part summary diagram." The solid part summary diagram is a graph in which the vertical axis represents the measured height, which is the distance from the tip part 11 in the height direction of the uneven part, and the horizontal axis represents the solid part ratio. In addition, the work of obtaining the solid part ratio is performed on multiple predetermined cut surfaces, and an average solid part summary diagram is created in which the average solid part ratios obtained from the multiple predetermined cut surfaces are plotted in order, so that the formation state of the convex parts 10 in the insert member 1 can be grasped on an average basis. In this case, in any of the predetermined cut surfaces, the reference point in the height direction is the "tip 11 of the most protruding convex portion 10 among the multiple convex portions 10 within the range of length d1," and the pitch of moving the line segment 20 is also set to the same pitch. This allows the measurement height to be uniquely determined even in multiple predetermined cut surfaces. Figure 3 shows an average solid portion summary diagram in which the average solid portion ratios that can be intermittently obtained from six predetermined cut surfaces of a certain sample are plotted in order, with the predetermined pitch set to 0.05 mm and the length d1 set to 14.7 mm, as an example of the insert member 1 according to this embodiment.

[0035] The average maximum height h1 of the unevenness is the absolute value of the value from the tip to the base on the vertical axis of the average solid part summary diagram. The tip corresponds to the tip 11 of the most protruding convex part 10 among the multiple convex parts 10 within the range of length d1 in the solid part summary diagram. The measured height at the tip is 0 mm, and the solid part ratio is 0. The base is the position where the solid part ratio plotted in sequence from the tip 11 side to the base 12 side exceeds 0.98 for the first time in the solid part summary diagram, and the average solid part summary diagram is the position where the average solid part ratio plotted in sequence from the tip 11 side to the base 12 side exceeds 0.98 for the first time. Note that the solid part ratio at each measurement point in the solid part summary diagram is measured from the tip 11 side of the convex part 10 located at the top toward the central axis C located at the bottom, so the measured height at each measurement point is displayed as a negative value. The same is true for the average solid part summary chart obtained from multiple solid part summary charts, but the actual height of the uneven part and the average maximum height h1 of the uneven part are the absolute values ​​of the vertical axis on the average solid part summary chart, and the average maximum height h1 is the distance from the base end to the tip end on the chart. Also, the line connecting each measurement point plotted on the average solid part summary chart is called the "average solid part curve."

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

[0037] [Measurement method] [Preparation of measurement samples] The following describes a method for measuring the length of the contour line 30 and the solid part ratio. First, a method for preparing a measurement sample is described. The insert member 1 cut in a direction along the axial direction including the central axis C is further cut in 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 part 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 size of the waterproof emery paper is changed in the order of #220, #400, #800, #1000, and #1500. After polishing is completed, the length of the contour line 30 and the solid part ratio are measured. The observation surface after polishing corresponds to a predetermined cut surface.

[0038] [Method of measuring peripheral surface length ratio] In this embodiment, the length of the contour line 30 was measured using a digital microscope RX-100 manufactured by Hirox Co., Ltd. The objective lens magnification during measurement was 20x or 40x, and when the average maximum height h1 of the uneven parts was large, for example, when it exceeded 0.30 mm, 20x was used. In the case of the device used this time, when the objective lens magnification was 20x, the length of the horizontal axis of the monitor was 14.7 mm, which was taken as the length d1. After setting the measurement sample after polishing, the measurement sample was set so that the inner peripheral surface 40 of the insert member 1 and the horizontal axis of the grid displayed on the observation monitor were parallel, and then the measurement sample was moved in parallel to a position where the outer peripheral surface could be observed. By using the "automatic area" tool of the software attached to the microscope and clicking on the insert member 1 part on the monitor to adjust the gradation density, the area and circumference of the insert member 1 part can be automatically measured based on 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 circumference measured is the entire circumference of the insert member 1 on the monitor, the length corresponding to the portion of the insert member 1 other than the contour line 30 is found and subtracted from the measured entire circumference. The length of the contour line 30 is found in this way. In this case, the length of the portion other than the contour line 30 can be found using the "auto width" tool attached to the microscope. The outer peripheral surface length ratio can be found by dividing the length of the contour line 30 found in this way by the length d1.

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

[0040] FIG. 2 illustrates the case where the line segment 20 is at position 20a and the case where it is at position 20b. Position 20a is the position of the tip 11 of the convex portion 10 that protrudes most within the range of length d1. When the line segment 20 is at the measurement height shown in position 20a, the line segment 20 overlaps with the tip 11 of the convex portion 10. Using this as a reference, the line segment 20 is moved in the direction shown by arrow A20 (toward the base end portion 12) at a predetermined pitch. Position 20b is an example of a measurement height when the line segment 20 is moved an arbitrary number of times at a predetermined pitch. When the line segment 20 is at the measurement height shown in position 20b, it can be said that the insert member 1 defines the solid part region 21 shown by the dashed line and the non-solid part region 22 shown by the solid line of the line segment 20. Line segment 20 is moved along arrow A20, and from the position where the solid part ratio described below exceeds 0.98 for the first time, line segment 20 is further moved along arrow A20, and the measurement is terminated when the entire range of length d1 on line segment 20 becomes solid part region 21 (i.e., when the solid part ratio becomes 1.00).

[0041] [Non-material part ratio] The non-substantial part ratio is the ratio of the non-substantial part to the total part of the [Ratio of non-solid part at any measurement height] = [Ratio of solid part at base end on drawing] - [Ratio of solid part at any measurement height] The above relationship holds true. In addition, in the average solid part summary chart, [Average non-solid part ratio at any measurement height] = [Average solid part ratio at the base end on the drawing] - [Average solid part ratio at any measurement height] The following relationship holds.

[0042] [Parameters for average solid part summary chart] It is preferable to form the convex portion 10 and the concave portion 13 so that the average maximum height h1 of the concave-convex portion is within a range of 0.15 mm to 1.50 mm in the average solid portion summary diagram. More preferably, the average maximum height h1 of the concave-convex portion is within a range of 0.20 mm to 1.00 mm. In this case, the length of the contour line 30 can be increased by increasing the average maximum height h1 of the concave-convex portion, but if the average maximum height h1 of the concave-convex portion is excessively large, the volume occupied by the convex portion 10 increases near the interface between the insert member 1 and the motor case, and the thermal resistance of conduction increases, so that there is a risk of impairing the thermal conductivity. On the other hand, by increasing the length of the contour line 30 while keeping the average maximum height h1 of the concave-convex portion at 1.50 mm or less, that is, by increasing the interface length ratio, it is possible to improve the thermal conductivity from the insert member 1 to the motor case and the heat dissipation from the motor case.

[0043] In addition, by setting the average maximum height h1 of the uneven portion to 1.50 mm or less, the insert member 1 can be made lighter and more compact. However, if the average maximum height h1 of the uneven portion is too small, the bonding strength 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. In general, the greater the bonding strength between the insert member 1 and the motor case, the better the thermal conductivity, so in order to maintain the bonding strength between the insert member 1 and the motor case, it is preferable to set the average maximum height h1 of the uneven portion to 0.15 mm or more. This makes it easier to prevent the insert member 1 from peeling off the motor case.

[0044] Here, in the average solid part summary diagram, the average solid part ratio at a position moved 0.10 mm in height from the base end to the tip end is referred to as the "first average solid part ratio", and the average non-substantial part ratio calculated based on the first average solid part ratio is referred to as the "first average non-substantial part ratio". The value of the first average solid part ratio is A, and the value of the first average non-substantial part ratio is B. At this time, the value obtained by dividing the outer peripheral surface length ratio by A is referred to as the "first interface parameter" for convenience. The first interface parameter is an aid in grasping the shape of the vicinity of the base end 12 of the protrusion 10. For example, a heating element such as a stator is disposed inside the insert member 1. At that time, the heat generated by the heating element is transferred from the vicinity of the base end 12 of the protrusion 10 to the tip end 11 where the motor case or the like is disposed. Therefore, in order to efficiently transfer the heat of the heating element to the motor case, it is preferable that the shape of the insert member 1 near the base end 12 is as flat as possible. Therefore, it is preferable that the first average solid portion ratio is as small as possible. In other words, it is preferable that the first interface parameter is large. In Fig. 3, the first average solid portion ratio at a position moved 0.10 mm in height from the base end to the tip end in the figure is shown as A, and the first average non-solid portion ratio at the same position is shown as B.

[0045] Furthermore, for convenience, the value obtained by dividing the outer peripheral surface length ratio by the height from the base end to the position where the average solid portion ratio is 0.30 on the diagram is referred to as the "second interface parameter." In FIG. 3, the "height from the base end to the position where the average solid portion ratio is 0.30 on the diagram" is indicated as h2. In other words, the height h2 is the "difference between the measured height of the base end on the diagram and the measured height of the position where the average solid portion ratio is 0.30." Here, if there are multiple positions where the average solid portion ratio is 0.30, the one closest to the base end on the diagram is used as the second interface parameter. The position on the side of the protrusion is the subject of evaluation. In other words, the height h2 is the height from the base end on the drawing to the position closest to the base end on the drawing where the average solid part ratio is 0.30. The second interface parameter makes it easier to grasp the shape of the protrusion 10 of the insert member 1 from the base end on the drawing to the position where the average solid part ratio is 0.30 based on the average solid part summary diagram. By using the above-mentioned first interface parameter and second interface parameter, the outer peripheral surface length ratio can be standardized at a certain position on the average solid part summary diagram, making it easier to confirm the correlation between the shape of the protrusion and the thermal conductivity.

[0046] The measurement height at the position where the average solid part ratio is 0.30 can be determined based on two consecutive points on the average solid part summary chart, that is, a point where the average solid part ratio is less than 0.30 and a point where the average solid part ratio is more than 0.30. Specifically, it can be determined from a function of a straight line connecting a point on the average solid part summary chart where the average solid part ratio is less than 0.30 and a point adjacent to that point where the average solid part ratio is more than 0.30.

[0047] By organizing the shape of the uneven portion in the insert member 1 of the present invention using the first interface parameter and the second interface parameter based on the outer peripheral surface length ratio and the average solid portion summary diagram, it is possible to identify an insert member 1 having even better thermal conductivity at the interface between the insert member 1 and the motor case.

[0048] [Testing and 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, the insert members of the Examples and Comparative Examples (hereinafter referred to as Examples, etc.) were subjected to measurement of various parameters, actual cutting tests, thermal conductivity measurements, and surface temperature simulations.

[0049] [Measurement of various parameters] Various parameters of the insert members according to the examples were measured. Table 1 shows the results of each measurement item of the insert members according to the examples. In measurement item 1, the insert members in each example were cut to obtain the outer peripheral surface length ratio. In measurement items 2 to 8, the average solid part summary chart in each example was used to obtain each value. When creating the average solid part summary chart in each example, the predetermined pitch was 0.05 mm or 0.025 mm. In addition, in the measurement of the outer peripheral surface length ratio, the predetermined axial length was 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. In addition, in the measurement of the average solid part ratio, the predetermined axial length was 14.7 mm in Examples 1 to 3, 6 to 11, and Comparative Examples 1 and 3, and 5.57 mm in Examples 4, 5, and Comparative Example 2. In addition, the parentheses in each measurement item are the units used, and those not listed are dimensionless numbers.

[0050] [1. Outer circumference length ratio] As measurement item 1, the outer peripheral surface length ratio was measured. In this case, the outer peripheral surface length ratio was obtained by cutting and polishing the insert member in the embodiment etc. along the axial direction by a virtual plane including the central axis C, and measuring the length of the contour line 30. In addition, in order to secure a predetermined axial length that can obtain the contour line 30, the insert member is also cut in a direction perpendicular to the axial direction (radial direction). The cut surface thus obtained was observed under a microscope. The outer peripheral surface length ratio was obtained by cutting out predetermined cut surfaces at any six places from one insert member and calculating the average value.

[0051] [2. Average maximum height of uneven parts h1 (mm)] As measurement item 2, the average maximum height h1 of the uneven portion was measured using the average solid portion summary chart in each Example, etc. For Comparative Example 1, since the value for the average maximum height h1 of the uneven portion was small, measurements of other items were 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 summary diagram in each Example, etc. As described above, the first average solid part ratio A is the average solid part ratio at a position moved 0.10 mm in height from the base end on the diagram toward the tip end on the diagram.

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

[0054] [5. 0.10 / First average non-substantial part ratio B(mm)] As measurement item 5, the gradient of the line connecting the measurement position of the first average solid part ratio A and the two points of the base end on the average solid part summary diagram of each Example, etc. (hereinafter referred to as the gradient 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 on the diagram in each Example, etc. Checking the gradient of the average solid part curve helps to understand the shape of the protrusion near the base end. The gradient 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-substantial part ratio B (mm)] As measurement item 6, the area of ​​a predetermined region was calculated in the average solid part summary diagram of each Example, etc., as follows. As with measurement item 5, the first average non-solid part ratio B is calculated in each Example, etc., by subtracting the first average solid part ratio A calculated in measurement item 3 from the average solid part ratio of the base end on the diagram. Here, the predetermined region is a rectangular region in the average solid part summary diagram, with a height of 0.10 mm from the base end on the diagram and a width of the first average non-solid part ratio B, and is a region including the average solid part curve from the base end on the diagram to a position moved 0.10 mm in height toward the tip end on the diagram. The area of ​​the predetermined region is calculated by [0.10 x first average non-solid part ratio B]. This helps to grasp the shape of the uneven part near the base end of the convex part.

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

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

[0058] The measurement results of various parameters measured as described above are shown in Table 1. [Table 1]

[0059] [Cutting test] In the actual cutting test, in each example, an aluminum alloy was used as an outer member, and a composite was produced by casting an insert member in the outer member. The outer member here means a member located radially outside the insert member, such as an example of a motor case. Furthermore, the composite was cut and a test piece of 20 mm x 20 mm was cut out. For each example, the test piece was cut out multiple times, and the presence or absence of peeling between the insert member and the outer member was judged, thereby evaluating the bondability between the insert member and the outer member. Specifically, six test pieces were cut out from each example, and the presence or absence of peeling was judged. The judgment criteria are shown in Table 2. [Table 2]

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

[0061] [Surface temperature simulation] In each example, a model was created with the insert member having a thickness of 2 mm, the composite portion (interface portion between the insert member and the outer member) having a thickness of 3 mm, and the outer member having a thickness of 2 mm, and the surface temperature of the outer member was simulated. In this case, the inner surface temperature of the insert member was set to 150°C, the fluid temperature on the outer periphery of the outer member was set to 50°C, and the surface temperature of the outer member was calculated on the assumption that a cooling fluid exists on the outer periphery of the outer member. In addition, the heat transfer from the surface of the outer member to the fluid was calculated with a heat transfer coefficient of 200 W / m 2 The name was K. Based on the surface temperature of the outer member obtained by the simulation, heat dissipation was evaluated according to the criteria shown in Table 3. In this case, the higher the surface temperature, the more efficiently the internal heat can be transferred, and the better the heat dissipation. [Table 3]

[0062] [Compactness evaluation] In measuring the various parameters described above, the compactness was evaluated according to the criteria shown in Table 4, based on measurement item 2, the average maximum height h1 of the uneven parts. [Table 4]

[0063] The overall evaluation was made based on the evaluation marks for each measurement item, as shown in Table 5. [Table 5]

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

[0065] From the results shown in Table 6, in the overall judgment, all of Examples 1 to 11 were superior to Comparative Examples 1 to 3. It was confirmed that Examples 2, 3, 4, and 5 were particularly excellent.

[0066] Furthermore, by comparing Examples 1 to 8 and 10 with Comparative Examples 1 to 3, it was confirmed that the thermal conductivity at the interface between the insert member and the motor case is increased by forming the uneven portion so that the first interface parameter is 1.30 or more and the second interface parameter is 4.00 or more.

[0067] In addition, in Examples 4, 5, and 10, the outer peripheral surface of the insert member was roughened by thermal spraying or cold spraying, and it was confirmed that the thermal conductivity was higher than that of the other Examples.

[0068] Moreover, by comparing Examples 1 and 9 with other Examples, it was confirmed that even when the outer peripheral surface length ratio is large, when the average maximum height h1 of the uneven portion is relatively large as in Examples 1 and 9, the thermal conductivity does not increase. In addition, it was confirmed that when the average maximum height h1 of the uneven portion is excessively large as in Comparative Example 3, the thermal conductivity at the interface between the insert member and the motor case decreases.

[0069] From the above results, it was confirmed that examples having a small value of the first average solid part ratio A and a large value of the first interface parameter had high thermal conductivity, such as Examples 4 and 5. Among the examples, Example 5, which had the largest first interface parameter, had the largest thermal conductivity at the interface between the insert member and the motor case.

[0070] From the above results, referring to Examples 1 to 11, the slope of the average solid part curve in the average solid part summary chart is 0.10 / B≦1.30 It was also confirmed that, with reference to Examples 2 to 5, when the gradient of the average solid part curve is small, the thermal conductivity at the interface between the insert member and the motor case is high.

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

[0072] From the above results, it was found that the insert member and the outer member peeled off when the test piece was cut out in the case of the outer peripheral surface length ratio being less than 1.15, as in Comparative Examples 1 and 2. Also, in the case of Examples 6 to 8, the outer peripheral surface length ratio being greater than 1.15 and less than 1.30, peeling sometimes occurred, and therefore it was confirmed that the outer peripheral surface length ratio is more preferably 1.30 or more.

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

[0074] [Effects] By forming the uneven portion according to the present invention on the outer peripheral surface of the insert member 1, the heat generation of the stator, etc. The thermal conductivity at the interface between the insert member 1 and the motor case can be improved so that the heat generated by the body can be efficiently dissipated to the outside.

[0075] The multiple protrusions 10 are arranged on the outer circumferential surface of the insert member 1 so that adjacent protrusions 10 are appropriately spaced apart. This allows the casting material poured into the mold to spread between the multiple protrusions 10, making it possible to prevent gaps from occurring between the motor case and the insert member 1, and improving the thermal conductivity at the interface between the motor case and the insert member 1.

[0076] In the insert member 1 of the present invention, the convex portions 10 and concave portions 13 are formed within the range of length d1 so as to ensure the length of the contour line 30 without making the concave and convex portions excessively large. This makes it possible to satisfactorily control the thermal conductivity at the interface between the insert member 1 and the motor case. This makes it possible to suppress an increase in the size and mass of the motor case itself due to an increase in the thickness of the motor case, realize a lightweight and compact rotating electric machine, and improve the thermal conductivity from the insert member 1 to the motor case and the heat dissipation of the rotating electric machine itself.

[0077] Although the embodiments of the present invention have been described above, each aspect disclosed in this specification can be combined with any other feature disclosed in this specification. [Explanation of symbols]

[0078] 1: Insert parts for rotating electrical machines 10: Convex part 13: Recess 20: Line segment 30: Contour 40: Inner surface C: Central axis of insert

Claims

1. A generally cylindrical insert member that is cast into an aluminum alloy motor case of a rotating electrical machine, The insert member has an outer peripheral surface formed with an uneven portion including a recess and a protrusion, In a cross section which is one of the cut surfaces appearing on both sides of the central axis when the insert member is cut into two parts 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 circumferential surface including the contour of the concave-convex portion within a predetermined axial length range 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; Insert material for rotating electrical machines.

2. the insert member defines, within the range of the predetermined axial length, a solid region where the insert member overlaps on a line segment parallel to an inner peripheral surface of the insert member when the line segment is overlapped on the cross section, and a non-solid region where the insert member does not overlap on the line segment, A value indicating a ratio of the solid portion region within the range of the predetermined axial length on the line segment is defined as a solid portion ratio, In the entire cross section of the insert member, the line segment is moved from the tip end of the convex portion that is the most protruding in the concave-convex portion toward the base end side of the convex portion at a predetermined pitch along the height direction of the concave-convex portion, and the values ​​of the solid portion ratio at each measurement point are plotted in order, and a diagram in which the horizontal axis represents the solid portion ratio and the vertical axis represents the distance from the tip end in the height direction as a measurement height is defined as a solid portion summary diagram, The average of the solid part ratios at the measurement points based on the plurality of cross sections is defined as an average solid part ratio, and the solid part summary chart in which the average solid part ratios are plotted in order is defined as an average solid part summary chart; In the average solid portion summary diagram, the position where the average solid portion ratio is 0 is defined as the tip portion on the diagram, and the position where the average solid portion ratio plotted in sequence from the tip portion side to the base portion side first exceeds 0.98 is defined as the base portion on the diagram, When the distance from the tip end to the base end is set 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 portion ratio at a position moved 0.10 mm in height from the base end portion in the figure toward the tip end portion in the figure is defined as A, the value obtained by dividing the outer circumferential surface length ratio by A is defined as a 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 the thickness of the insert member is half the value obtained by subtracting the inner diameter from the outer diameter 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 circumferential surface is subjected to a roughening treatment. The insert member for a rotating electrical machine according to claim 1 .

6. The outer circumferential surface of the insert member has, in a portion in the axial direction, at least one of a region in which the outer circumferential surface length ratio is less than 1.15 and a region in which the first interface parameter is less than 1.

30. The insert member for a rotating electrical machine according to claim 3 .

7. In the average solid part summary chart, When an average non-solid portion ratio is defined as a value obtained by subtracting the average solid portion ratio at a certain measurement height from the average solid portion ratio at the base end on the figure, and the average non-solid portion ratio at a position moved 0.10 mm in height from the base end on the figure toward the tip end on the figure 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 summary chart, When an average non-solid portion ratio is defined as a value obtained by subtracting the average solid portion ratio at a certain measurement height from the average solid portion ratio at the base end on the figure, and the average non-solid portion ratio at a position moved 0.10 mm in height from the base end on the figure toward the tip end on the figure is defined as B, 0.10×B≧0.01; The insert member for a rotating electrical machine according to claim 3 .

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

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