Insert member for rotary electric machine

Abstract

[Problem]To provide an insert member for a rotary electric machine, the insert member being capable of improving the strength of joint with a motor case. [Solution] A plurality of protrusion parts are formed on the outer circumferential surface of a substantially cylindrical insert member. In a cross section obtained by cutting the insert member, when a line segment having a predetermined axial length parallel to the inner circumferential surface of the insert member is overlapped with the cross section, a substantial part region in which the protrusion parts overlap with the line segment on the line segment and a non-substantial part region in which the protrusion parts do not overlap with the line segment on the line segment are defined. When a value indicating the ratio of the substantial part region is defined as a substantial part ratio on the line segment, a chart in which the values of the plurality of substantial part ratios are plotted in order is taken as a substantial part summary chart. In an average substantial part summary chart obtained from a plurality of cross sections, when a position where an average substantial part ratio is 0 is defined as a chart end and a position where the average substantial part ratio exceeds 0.98 for the first time is defined as a chart base, the average maximum height of the protrusion, which is the distance from the chart end to the chart base, is 0.08% or more of the outer diameter of the insert member.

Description

Inserts for rotating electrical machines

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

[0002] Conventionally, aluminum alloys have often been used as structural members in motor cases. To provide additional strength to the stator-mounted portion of the motor case, a high-strength, substantially cylindrical iron-based insert member has been used. In this regard, it has been proposed to improve the fixation and retention of the insert member relative to the motor case by providing irregularities on the outer circumferential surface of the insert member (see, for example, Patent Documents 1, 2, and 3).

[0003] JP 2001-169500 ​​A JP 2011-101513 A Japanese Patent No. 6655560 A

[0004] When forming a motor case from an aluminum alloy, the insert member described above is sometimes cast in. After casting, the insert member's inner surface is machined to fit onto the outer surface of the stator, forming a stator holder. In this case, if the bond strength between the motor case and the insert member is insufficient, the insert member may displace relative to the motor case, causing the motor shaft to wobble, increasing friction and resulting in reduced output, or increased vibration and reduced durability.

[0005] The technology of the present invention has been made in view of the above-mentioned circumstances, and an object of the present invention is to provide an insert member for a rotating electrical machine that can improve the joining strength with a motor case.

[0006] In order to solve the above-mentioned 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 an insert member having a substantially cylindrical shape that is cast into an aluminum alloy motor case of a rotating electric machine, the insert member having a plurality of protrusions formed on an outer peripheral surface thereof, the insert member having a cross section that is one of the cross sections that appear on both sides of the central axis when the insert member is cut into two along the axial direction by an imaginary plane including the central axis of the insert member, the insert member defining, within a predetermined axial length range, a solid region where the protrusions overlap on a line segment parallel to the inner peripheral surface of the insert member and a non-solid region where the protrusions do not overlap on the line segment, and a value indicating the proportion of the solid region within the predetermined axial length range on the line segment is defined as a solid region ratio, and The values ​​of the solid part ratios of each measurement point obtained by moving from the tip end of the protrusion toward the base end at a predetermined pitch along the height direction of the protrusion are plotted in order, with the solid part ratio represented on the horizontal axis and the distance from the tip end in the height direction represented as the measurement height on the vertical axis to form a solid part summary diagram. The average of the solid part ratios at each measurement point obtained from a plurality of the cross sections is defined as an average solid part ratio. The solid part summary diagram on which the average solid part ratio is plotted is defined as an average solid part summary diagram. In the average solid part summary diagram, the position where the average solid part ratio is 0 is defined as the tip end on the diagram, and the position where the average solid part ratio, plotted in order from the tip end side toward the base end side, first exceeds 0.98 is defined as the base end on the diagram. When the distance from the tip end on the diagram to the base end on the diagram is defined as the average maximum height of the protrusions, the average maximum height of the protrusions is 0.08% or more of the outer diameter of the insert member.

[0007] Furthermore, in the insert member, the average maximum height of the protrusions may be formed within a range of 0.08% to 1% of the outer diameter of the insert member.

[0008] Furthermore, in the average solid part summary diagram, the sum of the average solid part ratios in the range from the midpoint of the average maximum height of the protrusions to the tip ends on the diagram, excluding the positions of the tip ends on the diagram, may be greater than the sum of the average solid part ratios in the range from the midpoint of the average maximum height of the protrusions to the base ends on the diagram, excluding the positions of the base ends on the diagram.

[0009] Furthermore, two or more measurement points plotted on the average solid part summary chart may be included within a range in which the difference in the average solid part ratios between the two or more measurement points is 0.10 or less and the difference in the measurement heights between the two or more measurement points is 0.05 mm or more.

[0010] Furthermore, the average body part ratios plotted on the average body part summary chart may have a maximum peak in the value of the average body part ratio and a minimum peak in the value of the average body part ratio, and the position of the maximum peak may be configured to appear closer to the tip end of the chart than the position of the minimum peak.

[0011] In addition, in the average solid body summary chart, the value of the average solid body ratio at the minimum peak may be 0.08 or more.

[0012] In addition, in the average solid body summary chart, the difference between the average solid body ratio value at the maximum peak and the average solid body ratio value at the minimum peak may be 0.02 or more and 0.20 or less.

[0013] In addition, in the average solid body summary chart, the value of the average solid body ratio at the maximum peak may be 0.50 or less.

[0014] The protrusion may be formed only on a partial area of ​​the outer peripheral surface of the insert member.

[0015] According to the present invention, it is possible to provide an insert member for a rotating electrical machine that can improve the bonding strength with a motor case.

[0016] Fig. 1 is an overall view of an insert member for a rotating electric machine according to an embodiment, and an enlarged view of a portion of its outer circumferential surface. Fig. 2 is a cross-sectional view showing an example of a predetermined cut surface of an insert member for a rotating electric machine according to an embodiment. Fig. 3 is an average solid portion summary diagram for explaining the relationship between the measurement height and the average solid portion ratio of an insert member for a rotating electric machine according to an example embodiment. Fig. 4 is an average solid portion summary diagram of an insert member for a rotating electric machine according to an example embodiment. Fig. 5 is an average solid portion summary diagram of an insert member for a rotating electric machine according to an example embodiment.

[0017] 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 additions, omissions, substitutions, and other modifications of the configurations are possible as appropriate within the scope of the gist of the present invention.

[0018] 1 is an overall view of an insert member 1 for a rotating electrical machine according to an embodiment (hereinafter referred to as "insert member 1"), and an enlarged view of a portion 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, extending 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. The axial, radial, and circumferential directions are merely directions used to indicate the relative positional relationships of the elements in the insert member 1.

[0019] The insert member 1 according to this embodiment is, for example, a cast iron material formed into a substantially cylindrical shape centered on a central axis C, with multiple protrusions 10 formed on its outer circumferential surface (surface). A rotating electric machine to which the present invention is applicable is, for example, a motor used in an electric vehicle or the like. However, the rotating electric machine to which the present invention is applicable 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 this may be changed as appropriate depending on the intended use. Furthermore, 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 such that the central axis C of the insert member is parallel to the plane, and the tip ends 11 of the protrusions 10 on the outer circumferential surface of the insert member 1 are brought into contact with the two parallel planes.

[0020] A rotating electric 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 section hollowed out in a cylindrical shape. The stator is generally formed from an electromagnetic steel sheet or the like and is fitted into the inner periphery of the cylindrical section. Here, the insert member 1 is used by being cast into the inner periphery of the motor case made of an aluminum alloy. This results in the motor case and the insert member 1 forming a composite structure in which at least a portion of the outer periphery of the insert member 1 is covered with an aluminum alloy. Furthermore, when the stator is fitted into the inner periphery of the insert member 1, the stator is shrink-fitted. However, because the linear expansion coefficient of the stator material and the linear expansion coefficient of the insert member 1 are close to each other, the fitting strength between the stator and the insert member 1 is maintained even when heat is generated during motor operation.

[0021] Generally, the operating temperature of a motor is −30° C. to 150° C. The material used for the stator is generally an electromagnetic steel plate. －６ / K or more 13.0×10 －６When the insert member 1 is formed using a material having a linear expansion coefficient of 1 / K or less, the linear expansion coefficients of the stator and the insert member 1 to be fitted together become similar. This helps to maintain a high level of fitting strength between the outer periphery of the stator and the inner periphery of the insert member 1 even after the stator is fitted into the insert member 1 cast into the motor case.

[0022] The material of the insert member 1 is not particularly limited as long as it has sufficient strength compared to the aluminum alloy used for the motor case and has a linear expansion coefficient within the above range. Typically, flake graphite cast iron such as JIS FC250 equivalent material can be used, taking into account manufacturability and processability.

[0023] The method for forming the protrusions 10 of the insert member 1 is not particularly limited, but for example, centrifugal casting can be used. Alternatively, the protrusions 10 can be formed by machining a cylinder made of cast iron.

[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 refers to a cross section, which is one of the cut surfaces that appear on both sides of the central axis C when the insert member 1 is cut axially into two parts by an imaginary plane including the central axis C of the insert member 1. The axial length of the cross section is equal to or greater than the length d1 described below. FIG. 2 illustrates the A-A' cross section in FIG. 1 as an example of a predetermined cut surface. Also, the reference numeral 40 in FIG. 2 indicates the inner peripheral surface of the insert member 1. Hereinafter, this will be referred to as the "inner peripheral surface 40." Below, the multiple protrusions 10 provided on the insert member 1 according to this embodiment will be described using FIG. 2.

[0025] The protrusions 10 are part of the insert member 1 and are formed on the outer peripheral surface of the insert member 1. The protrusions 10 may be arranged in multiple locations and at random intervals in the axial and circumferential directions, or may be arranged in multiple locations and at regular intervals in the axial and circumferential directions. The protrusions 10 have a tip end 11 and a base end 12, and are formed so as to protrude from the base end 12 to the tip end 11 radially outward of the insert member 1.

[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 processing such as scraping off some of the multiple protrusions 10 may be performed. As a result, the multiple protrusions 10 may be formed only in a partial area of ​​the outer peripheral surface of the insert member 1.

[0027] The protrusions 10 may be formed by casting under centrifugal force using a centrifugal casting method. In this case, the tip ends 11 of the protrusions 10 are formed based on the inner peripheral surface of the mold. Therefore, if the inner peripheral surface of the mold is a perfect circle, the distances from the central axis C of the insert member 1 will be approximately equal, whereas the distances from the central axis C of the base ends 12 may vary. For this reason, the height of the protrusions 10 is measured based on the tip ends 11 in the process of deriving the height of the protrusions 10 using a substantial part summary diagram described below. However, the method of forming the protrusions 10 is not limited to this, and the protrusions 10 may also be formed, for example, by machining the outer peripheral surface of a cylindrical member, such as by cutting.

[0028] Furthermore, 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, tensile simulation, and shear simulation described below.

[0029] [Solid Portion Ratio] The protrusion 10 of the insert member 1 defines a solid portion region 21 and a non-solid portion region 22. As shown in Figure 2, the solid portion region 21 and the non-solid portion region 22 are identified based on whether a line segment 20 having a length d1 (an example of the "predetermined axial length" in the present invention) overlaps with the protrusion 10 when the line segment 20 is superimposed on a predetermined cross-section. More specifically, within the range of length d1, the region where the line segment 20 overlaps with the protrusion 10 is defined as the solid portion region 21, and the region where the line segment 20 does not overlap with the protrusion 10 is defined as the non-solid portion region 22. The line segment 20 is a virtual line parallel to the inner circumferential surface 40 (i.e., parallel to the central axis C) on the predetermined cross-section, and is provided for convenience in identifying the solid portion region 21 and the non-solid portion region 22.

[0030] The solid body ratio is a value indicating the proportion of the solid body region 21 formed within the range of length d1. By moving the line segment 20 at a predetermined pitch in the direction of arrow A20 in FIG. 2 (from the distal end 11 side to the proximal end 12 side in the radial direction), the length of the solid body region 21 at a measurement height at an arbitrary measurement point within the measurement height, which is the radial distance from the distal end 11, can be obtained. In this case, the ratio of the total length of the solid body region 21 to the length d1 at the arbitrary measurement height is referred to as the "solid body ratio." By performing the same operation on multiple cross sections, aggregating the solid body ratios of the protrusion 10 on each cut surface, and averaging the solid body ratios at the measurement heights of each measurement point, an average solid body ratio can be obtained, which is the average value of the solid body ratios based on multiple cross sections at the arbitrary measurement height.

[0031] [Solid Body Summary Diagram] As shown in FIG. 2 , by moving the line segment 20 toward the base end 12 (in the direction of arrow A20) at a predetermined pitch, the solid body ratio is repeatedly obtained until the solid body ratio reaches 1.00, and the obtained solid body ratio is plotted on a graph, thereby enabling the shapes of multiple protrusions 10 appearing on a predetermined cross section to be summarized and represented as a single graph. This is called a "solid body summary diagram." The solid body summary diagram is a graph in which the vertical axis represents the measured height, which is the distance from the tip end 11 in the height direction of the protrusions 10, and the horizontal axis represents the solid body ratio. Furthermore, by performing the process of determining the solid body ratio on multiple predetermined cross sections and creating an average solid body summary diagram, the formation state of the protrusions 10 in the insert member 1 can be grasped on average. In this case, for each predetermined cut surface, the reference point in the height direction is the tip 11 of the most protruding protrusion 10 among the multiple protrusions 10 within the range of length d1 (predetermined axial length), 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 for multiple predetermined cut surfaces. Furthermore, in this embodiment, protrusions identified by the graph shape appearing in the average body summary chart are referred to as "aggregated protrusions" in the average body summary chart. Figure 3 shows an example of an insert member 1 according to this embodiment, in which the average body ratios obtained intermittently from six predetermined cut surfaces of a sample are plotted in order, with a predetermined pitch of 0.05 mm and a length d1 of 14.7 mm. As shown in Figure 3, protrusions identified by the graph shape appearing in the average body summary chart are shown as aggregated protrusions 30.

[0032] [Measurement Method] The measurement method for the solid portion region 21 and the non-solid portion region 22 will be described below with reference to FIG. 2 . First, a method for preparing a measurement sample will be described. The insert member 1 is cut in a direction including the central axis C and along the axial direction, and then cut into a size that allows resin embedding and polishing. The resin embedding is performed with the entire cross section, where the solid portion ratio is to be measured, facing downward. After the resin has solidified, the entire cross section side is polished under running water using waterproof emery paper. At this time, the grit size of the waterproof emery paper is changed in the following order: #220, #400, #800, #1000, and #1500. After polishing is complete, the solid portion ratio is measured. The observation surface after polishing corresponds to the specified cut surface.

[0033] In this embodiment, a Hirox RX-100 digital microscope was used to measure the solid portion ratio. The objective lens magnification during measurement was 20x or 50x, and the grid and automatic width tool provided with the microscope were used. The measurement sample was set after polishing as described above, so that the inner circumferential surface 40 of the insert member 1 was parallel to the horizontal axis of the grid displayed on the observation monitor. The measurement sample was then translated to a position where the outer circumferential surface of the insert member 1 could be observed. Next, the automatic width tool was used to measure the measurement sample in the horizontal axis direction. Measurements using the automatic width tool are performed automatically using gradation density. Therefore, the gradation density is adjusted each time to ensure proper automatic discrimination between the insert member area corresponding to the solid portion region 21 and the resin area corresponding to the non-solid portion region 22. The measurement tool then moves at a predetermined pitch to measure the length of the solid portion region 21 at any measurement height. In this embodiment, line segment 20 indicates the measurement position of the automatic width tool. By moving the line segment 20 from the tip end 11 side toward the base end 12 side along the radial direction of the insert member 1, it is possible to measure the axial length of the solid body region 21 at any measurement height from the tip end 11. In this case, the line segment 20 is moved in all cross sections from the tip end 11 of the protrusion 10 that protrudes most within the range of length d1 toward the base end 12 side at a predetermined pitch of 0.05 mm or 0.025 mm, and measurements are taken.

[0034] 2 shows the case where the line segment 20 is at position 20a and the case where it is at position 20b. When the line segment 20 is at the measurement height indicated by position 20a, the line segment 20 overlaps with the tip portion 11 that protrudes the most within the length d1. Using this as a reference, the line segment 20 is moved in the direction of arrow A20 (toward the base end portion 12). Position 20b is an example of the 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 position indicated by position 20b, it can be said that the insert member 1 forms a substantial portion region 21 indicated by a dashed line and a non-substantial portion region 22 indicated by a solid line within the line segment 20. Line segment 20 is moved along arrow A20, and from the position where the solid body ratio (described below) exceeds 0.98 for the first time, line segment 20 is further moved along arrow A20 until the entire range of length d1 on line segment 20 falls within solid body region 21 (i.e., when the solid body ratio becomes 1.00), and measurement is terminated.

[0035] [Parameters of the Average Solid Body Summary Diagram] Figure 3 shows an average solid body summary diagram in which the average solid body ratios based on a certain sample are plotted in order. As shown in Figures 2 and 3, the position corresponding to the "tip 11 of the most protruding protrusion 10 among the multiple protrusions 10 within the range of length d1" in the average solid body summary diagram is referred to as the "tip on the diagram." The tip on the diagram is the position that coincides with the tip of the aggregated protrusions 30 described above. The measurement height at the tip on the diagram is 0 mm, and the average solid body ratio is 0. In addition, the "position among the points plotted on the average solid body summary diagram where the average solid body ratio first exceeds 0.98" is referred to as the "base end on the diagram."

[0036] The average solid body summary chart shown in Figure 3 shows maximum peak values ​​and minimum peak values. The maximum peak value is an "average solid body curve" formed by connecting the measurement points plotted on the average solid body summary chart with a line. The maximum peak value indicates the average solid body ratio at the maximum peak among the peaks in the average solid body curve. The minimum peak value indicates the average solid body ratio at the minimum peak among the peaks in the average solid body curve plotted on the average solid body summary chart. In an example of the average solid body summary chart shown in Figure 3, the absolute value of the measurement height from the tip to the maximum peak on the chart is 0.20 mm, the maximum peak value is 0.45, and the absolute value of the measurement height from the tip to the minimum peak on the chart is 0.45 mm, and the minimum peak value is 0.30. In this case, the maximum peak appears closer to the tip on the chart than the minimum peak in the measurement height direction.

[0037] The average maximum height h1 of the aggregated protrusions 30 shown in Figure 3 is the distance from the tip to the base on the vertical axis of the average solid body summary chart. The solid body ratio at each measurement point on the solid body summary chart is measured from the tip 11 of the protrusion 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. As is the case with an average solid body summary chart calculated from multiple solid body summary charts, the average maximum height h1 of the actual protrusions 10 is the absolute value of the value on the vertical axis on the average solid body summary chart.

[0038] In this embodiment, the protrusion 10 is formed so that the maximum peak value is ≦0.50 in the average material part summary diagram. As a result, the protrusion 10 is formed so that the base end 12 side is wider than the tip end 11 side. This allows the aluminum alloy poured into the mold when the insert member 1 is cast from an aluminum alloy to easily flow toward the base end 12 side of the protrusion 10, preventing voids from forming at the joint between the insert member 1 and the motor case. Furthermore, the protrusion 10 is less likely to break when a load is applied to it. The shape of the tip end 11 of the protrusion 10 is not particularly limited, and as long as it is formed so that the maximum peak value is ≦0.50, the tip end 11 may be formed, for example, in a round, angular, or flat shape.

[0039] The plurality of protrusions 10 may be formed so that the maximum peak appears closer to the tip end than the minimum peak in the average solid body summary diagram. Furthermore, in the average solid body summary diagram, the sum of the average solid body ratios in the range from the center of the average maximum height h1 of the aggregated protrusions 30 to the base end, excluding the base end, may be greater than the sum of the average solid body ratios in the range from the center of the average maximum height h1 of the aggregated protrusions 30 to the base end, excluding the base end. Here, if the center of the average maximum height h1 of the aggregated protrusions 30 coincides with the measurement point of the average solid body ratio, the center of the average maximum height h1 of the aggregated protrusions 30 is considered to be included on the tip end side. These factors make it possible to determine whether the tip end side of the aggregated protrusions 30 is thinner than the base end side.

[0040] In the aggregated protrusions 30, the position of the maximum peak may be closer to the base end in the figure than the tip end in the figure where the measurement height is 0 mm. In this way, in the aggregated protrusions 30, no maximum peak is formed at the tip end in the figure, so that damage or breakage of the tip end 11 of the protrusions 10 can be prevented.

[0041] The average solid body ratio may include two or more measurement points among the multiple measurement points plotted on the average solid body summary chart, within a range where the difference between the average solid body ratios of two or more measurement points is 0.10 or less and the difference in measurement height between two or more measurement points is 0.05 mm or more. As an example, FIG. 3 illustrates plots of points N1 to N3. The values ​​plotted at points N1 to N3 are plotted within a range where the difference between the average solid body ratios is a maximum of 0.007 and the difference in measurement height is a maximum of 0.10 mm. In this way, when the difference between the average solid body ratios of two or more measurement points is 0.10 or less and the difference in measurement height between two or more measurement points is 0.05 mm or more, the slope of the average solid body curve in the average solid body summary chart becomes steep. In this way, in the average solid part summary diagram, in a portion of the aggregated protrusions 30, where the slope of the average solid part curve is steep, on average, a portion of the plurality of protrusions 10 is formed approximately perpendicular to the outer peripheral surface of the insert member 1. As a result, even if, for example, the aggregated protrusions 30 have a graph shape in which no maximum peak appears, the bonding strength between the motor case and the insert member 1 can be improved by having a portion of the aggregated protrusions 30 where the slope of the graph is steep.

[0042] In the average substance summary diagram, the difference between the maximum peak value and the minimum peak value may be 0.02 or more and 0.20 or less. If the difference between the maximum peak value and the minimum peak value is less than 0.02, the bond strength between the motor case and the insert member 1 may be reduced compared to when the difference between the maximum peak value and the minimum peak value is 0.02 or more. Furthermore, if the difference between the maximum peak value and the minimum peak value exceeds 0.20, when the insert member 1 is cast from an aluminum alloy, the aluminum alloy poured into the mold may have difficulty flowing toward the base end 12 of the protrusion 10, or a portion of the formed protrusion 10 may be broken or damaged. In contrast, by setting the difference between the maximum peak value and the minimum peak value to 0.02 or more and 0.20 or less, high bond strength can be ensured while preventing damage to the protrusion 10.

[0043] In the average solid part summary diagram, the minimum peak value may be 0.08 or more. If the minimum peak value is below 0.08, it may be difficult to form the protrusions 10 during the manufacturing process of the insert member 1, or the protrusions 10 may be prone to breakage. In contrast, by setting the average solid part ratio of the minimum peak value to 0.08 or more, it is possible to prevent the number of protrusions 10 from becoming excessively small. In addition, this eliminates the lack of strength caused by the protrusions 10 becoming excessively thin, making the protrusions 10 less likely to break.

[0044] In the average solid portion summary diagram, the maximum peak value may be 0.50 or less, and more preferably 0.45 or less. If the maximum peak value is greater than 0.50, when the insert member 1 is cast from an aluminum alloy, there is a risk that the aluminum alloy poured into the mold will not spread easily among the multiple protrusions 10. In particular, there is a risk that the aluminum alloy will not spread easily toward the base end 12. Furthermore, there is a risk that the edges of the protrusions 10 will be chipped near the position where the average solid portion ratio value reaches its maximum peak, or that the protrusions 10 will be prone to breakage near the position where the average solid portion ratio value reaches its minimum peak. In contrast, these problems can be prevented if the maximum peak value is 0.50 or less, more preferably 0.45 or less.

[0045] [Tests and Simulations] The insert members 1 of Examples 1 to 13 of the present invention and the insert members of Comparative Examples were evaluated by tests and simulations using samples. Specifically, the insert members of Examples and Comparative Examples (hereinafter referred to as Examples, etc.) were subjected to measurement and evaluation of various parameters, actual cutting tests, tensile simulations, and shear simulations.

[0046] [Measurement and Evaluation of Various Parameters] Various parameters of the insert members according to each example were measured and evaluated. Table 1 shows the results for each item of the insert members according to the examples. For the insert members according to the examples, the pitch was set to 0.05 mm or 0.025 mm, the length d1 was set to 14.7 mm or 5.57 mm, and a high objective lens magnification was selected when the average maximum height h1 of the protrusions was small, and an average solid part summary chart was created. As a reference example, Table 1 shows various parameters of an insert member without protrusions 30.

[0047] [1. Ratio of average maximum height h1 of protrusions to outer diameter OD] In item 1, the ratio of the average maximum height h1 of the aggregated protrusions 30 to the outer diameter OD of the insert member was calculated as a percentage in the average substance part summary diagram for each example, etc. This confirmed whether the aggregated protrusions 30 in the examples, etc. were formed within a range of 0.08% to 1% of the outer diameter OD of the insert member.

[0048] [2. Whether the base end side on the figure is thicker than the tip end side on the figure] In item 2, based on the average solid portion summary diagram of each example, a determination was made as to whether the total value of the average solid portion ratios excluding the tip end position on the figure was greater than the total value of the average solid portion ratios excluding the base end position on the figure in the range from the center position of the average maximum height h1 of the aggregated protrusions 30 to the tip end on the figure. Based on the average solid portion summary diagram of each example, if the base end side on the figure is larger than the tip end side on the figure (i.e., if the base end side on the figure is thicker), it was marked with "O", and if the base end side on the figure of the aggregated protrusions 30 is equal to or smaller than the tip end side on the figure, it was marked with "X".

[0049] [3. Whether or not two or more measurement points are included where the difference in average solid part ratio is 0.10 or less and the difference in measurement height is 0.05 mm or more] In item 3, it was determined whether or not the average solid part ratio plotted in the average solid part summary chart for each Example, etc. included two or more measurement points where the difference in average solid part ratio was 0.10 or less and the difference in measurement height was 0.05 mm or more. If it included a point that could meet these conditions, it was marked with "O", and if it did not, it was marked with "X".

[0050] [4. Presence or absence of maximum peaks and minimum peaks] In item 4, in the average solid part summary diagram in each Example, etc., if a maximum peak and a minimum peak exist, and the maximum peak is located closer to the tip end on the diagram than the center position of the average maximum height h1 of the protrusions, and closer to the tip end on the diagram than the minimum peak, the mark is marked "◯." If the maximum peak is located closer to the tip end on the diagram than the center position of the average maximum height h1 of the protrusions, and closer to the base end on the diagram than the minimum peak, or if no peak appears on the average solid part summary diagram, the mark is marked "X."

[0051] [5. Minimum Peak Value] [6. Difference Between Maximum Peak Value and Minimum Peak Value] In item 5, the minimum peak value was determined based on the average substance part summary chart for each Example, etc. In item 6, the difference between the maximum peak value and the minimum peak value was determined based on the average substance part summary chart for each Example, etc.

[0052] [7. Position of Maximum Peak] In item 7, based on the average body summary chart in each Example, if the maximum peak is located closer to the base end than the tip end on the chart, it is marked with "O", and if no peak appears on the average body summary chart, it is marked with "X".

[0053] Further, a real cutting test, a tensile simulation, and a shear simulation were carried out on the insert members according to the examples and the like that were measured as shown in Table 1. The tests and simulations will be described below.

[0054] [Substantial Cutting Test] In the substantial cutting test, the insert member in the examples was cast in an aluminum alloy equivalent to the motor case. Furthermore, test pieces 20 mm square were cut out of the bonded insert member and aluminum alloy to confirm the bond strength. In this case, if the bond between the insert member and the aluminum alloy was maintained in all six test pieces subjected to the substantial cutting test, it was rated as A0. If the insert member and the aluminum alloy separated in some test pieces, it was rated as B0. If the insert member and the aluminum alloy separated in all six test pieces subjected to the substantial cutting test, it was rated as C0. The results are shown in Table 4, and details will be described later.

[0055] [Tensile Simulation] Typically, when an insert member cast in aluminum alloy is cut from its cast state, the aluminum alloy outside the insert member undergoes solidification and thermal contraction during the cooling process after die-casting, clamping the protrusions formed on the outer periphery of the insert member and partially releasing the clamping force between the insert member and the aluminum alloy. This makes it difficult to measure the actual joint strength. In contrast, in this simulation, a protrusion was formed by aggregating multiple protrusions into a single protrusion based on an average solid part summary diagram. The radial displacement difference of the protrusion when the difference in linear expansion coefficient between the aluminum alloy and the cast iron insert member occurs was evaluated using CAE analysis. The evaluation was performed under the following temperature conditions: high temperature: 150°C, medium temperature: 85°C. A representative example will be described with reference to Figure 3.

[0056] As described above, FIG. 3 shows an aggregated protrusion 30, which is a shape in which multiple protrusions 10 are aggregated into one based on the average solid part summary diagram. The aggregated protrusion 30 is defined by a region in the average solid part summary diagram where the vertical axis direction can be considered as the radial direction of the insert member 1 and the horizontal axis direction can be considered as the axial direction of the insert member 1. By reducing the aggregated protrusion 30 so that the horizontal axis length of the aggregated protrusion 30 in the average solid part summary diagram is halved while maintaining the vertical axis length, and then rotating the average solid part summary diagram about the vertical axis of the average solid part summary diagram, a model of the protrusion (referred to as a "model protrusion") in which the protrusion shapes of the insert member 1 are aggregated into one can be obtained. Here, the reason for reducing the horizontal axis length of the aggregated protrusion 30 by half is to define a model protrusion in which protrusion shapes existing within the range of length d1 are aggregated into one, and to perform simulations using the model protrusion. The thickness of the reduced aggregated protrusions was determined by converting the horizontal length of the reduced aggregated protrusions to the length d1. In this simulation, a model was created by casting an insert member with two model protrusions formed on the outer surface at 180° angles from each other in an aluminum alloy. The model was subjected to temperature changes under the above-mentioned temperature conditions, and the radial displacement was simulated using CAE analysis to perform a tensile evaluation simulating thermal expansion. The evaluation was performed based on the difference in radial displacement between the aluminum alloy and the insert member and the ratio of this difference to the average maximum height h1 of the protrusions, as shown in Table 2.

[0057] [Shear Simulation] In the shear simulation, a model insert member with one model protrusion formed on its outer peripheral surface was created by casting it in aluminum alloy, and a shear evaluation was performed assuming axial torque acting on the insert member. In this simulation, loads simulating shear occurring in the axial and circumferential directions were applied to the model protrusion cast in aluminum alloy. In this case, it was assumed that the shear load acting on the outer peripheral surface of the insert was a load equivalent to the motor shaft torque. The radial displacement difference between the aluminum alloy and the insert member was evaluated based on the ratio of this displacement difference to the average maximum height h1 of the protrusion, as shown in Table 3.

[0058] Table 4 shows the results of the actual cutting test, tensile simulation, and shear simulation measured as described above, as well as an overall evaluation based on these results.

[0059] In the overall assessment, if the actual cutting test, tensile simulation, and shear simulation all received an A rating, the overall assessment was A; if any of the actual cutting test, tensile simulation, and shear simulation received a C rating, the overall assessment was C; and if the results were anything other than these, the overall assessment was B.

[0060] From the above results, and with reference to the examples, it was confirmed that the average maximum height h1 of the aggregated protrusions 30 is preferably formed within a range of 0.08% to 1% of the outer diameter OD, and more preferably 0.26% or more of the outer diameter OD. It was also confirmed that if the average maximum height h1 of the aggregated protrusions 30 is less than 0.26%, the bonding strength between the insert member and the motor case decreases.

[0061] From the above results, by comparing Examples 1 to 5 and 8 with Examples 6, 7, 9 to 13 and the Comparative Example, it was confirmed that if the minimum peak value is 0.08 or more, the results of the tensile simulation and the shear simulation are excellent even under high temperature conditions. Similarly, it was confirmed that it is preferable that the difference between the maximum peak value and the minimum peak value is 0.02 or more.

[0062] In view of these results, it can be said that the insert member 1 according to this embodiment can prevent insufficient bonding strength with the motor case.

[0063] Next, of the above-mentioned tests and simulations, Examples 13, 11, and 2 will be used as examples to explain the average substantial part summary chart and the aspects of the insert member 1 in each example. FIG. 4 is an average substantial part summary chart of the insert member 1 in Example 13 according to this embodiment. FIG. 5 is an average substantial part summary chart of the insert member 1 in Example 11 according to this embodiment. FIG. 3 is an average substantial part summary chart of the insert member 1 in Example 2 according to this embodiment. Below, the average substantial part summary chart and the insert member 1 in each example according to this embodiment will be explained with reference to FIG. 4 for Example 13, FIG. 5 for Example 11, and FIG. 3 for Example 2.

[0064] FIG. 4 shows a reduced aggregated protrusion 301 obtained by reducing the aggregated protrusion 30 of Example 13 to half the length in the horizontal direction of the average substantial part summary diagram. Considering the model protrusion based on the reduced aggregated protrusion 301, it was confirmed that in the insert member 1 according to the average substantial part summary diagram shown in FIG. 4 , the aggregated protrusion 30 has a cross-sectional shape that is approximately triangular and protrudes radially, widening from the distal end 11 to the proximal end 12. Furthermore, the protrusions 10 formed on the insert member 1 may be individually present or may be continuously formed along the circumferential direction. Furthermore, when continuously formed along the circumferential direction, they may be arranged spirally on the outer peripheral surface of the insert member 1, or may be formed in a ring shape and continuously in the circumferential direction. In Example 13, the maximum height of the aggregated protrusion 30 was formed to be 0.08% or more of the outer diameter (OD) of the insert member 1, confirming that the insert member 1 and the motor case on its outer peripheral surface had a practical bonding strength.

[0065] Figure 5 shows a reduced aggregated protrusion 302 obtained by reducing the aggregated protrusion 30 of Example 11 to half the length in the horizontal direction of the average solid body summary diagram. Considering the model protrusion based on the reduced aggregated protrusion 302, it was confirmed that the average solid body curve in the insert member 1 according to the average solid body summary diagram shown in Figure 5 has a steep portion. When the average solid body curve is formed to have a steep portion, forces due to solidification shrinkage and thermal contraction of the aluminum alloy occurring in the circumferential direction are likely to occur in the circumferential direction. Excellent results were obtained in the solid cutting test without peeling, confirming that this helps improve the bonding strength between the insert member 1 and the motor case on its outer peripheral surface.

[0066] Figure 3 shows a reduced aggregated protrusion 303 obtained by reducing the aggregated protrusion 30 of Example 2 to half its length in the horizontal direction of the average body summary diagram. According to this, in the insert member 1 according to the average body summary diagram shown in Figure 3, the aggregated protrusion 30 has a hook shape with a maximum peak and a minimum peak formed midway between the distal end 11 and the proximal end 12, as shown in Figure 2. It was also confirmed that in this case, the maximum peak appears closer to the distal end than the minimum peak in the average body summary diagram.

[0067] As described above, in the configuration of Example 2, statistically speaking, the protrusions 10 formed on the outer peripheral surface of the insert member 1 have a hook shape. As a result, the hook shape of the protrusions 10 tightly meshes with the motor case on the outer peripheral surface side, significantly improving the bonding strength between the insert member 1 and the motor case on the outer peripheral surface side.

[0068] [Effects] By forming the protrusions 10 on the outer peripheral surface of the insert member 1, it is possible to improve the bonding strength between the insert member 1 and the motor case on the outer peripheral surface side of the insert member 1. It is also possible to prevent displacement or misalignment of the insert member 1 relative to the motor case in the axial, circumferential, and radial directions.

[0069] If the multiple protrusions 10 are arranged on the outer peripheral surface of the insert member 1 with an appropriate gap between adjacent protrusions 10, the aluminum alloy poured into the mold will spread appropriately between the multiple protrusions 10. As a result, it is possible to prevent gaps from forming between the motor case and the insert member 1, improving the bonding strength between the motor case and the insert member 1. In particular, even in motor cases manufactured by gravity casting, which is considered difficult for the aluminum alloy to spread to every corner, the aluminum alloy will easily spread between the protrusions on the outer peripheral surface of the insert member 1.

[0070] Furthermore, the insert member 1 is firmly fixed to the motor case in the axial, circumferential, and radial directions. This allows the inner periphery of the insert member 1 to be machined to form a stator holder, with a stator fitted to the inner circumferential surface 40, and prevents the stator from displacing in each direction even when the motor is running. As a result, improvements in the reliability, durability, and continuous operating time of the motor can be expected, as well as reduced loss and improved performance due to reduced friction.

[0071] The insert member 1 of the present invention can maintain the bonding strength between the motor case and the insert member 1, thereby preventing misalignment or the occurrence of small gaps between the insert member 1 and the motor case. Furthermore, by preventing such misalignment and gaps when the motor is in operation, it is possible to prevent the surfaces in the gap from being hit by micro-vibrations, causing wear and reducing the durability of the motor itself.

[0072] 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.

[0073] 1: Insert member for rotating electrical machine 10: Protrusion 20: Line segment 30: Aggregated protrusions C: Central axis of insert member

Claims

1. A substantially cylindrical insert member to be cast into an aluminum alloy motor case for a rotating electrical machine, the insert member having a plurality of protrusions formed on its outer peripheral surface, the insert member being cut axially into two parts by an imaginary plane including the central axis of the insert member, and in a cross section which is one of the cut surfaces appearing on either side of the central axis when the insert member is cut axially into two parts by an imaginary plane including the central axis of the insert member, the insert member defines, within a predetermined axial length range, a solid region where the protrusions overlap on a line segment parallel to the inner peripheral surface of the insert member and a non-solid region where the protrusions do not overlap on the line segment, and a value indicating the proportion of the solid region within the predetermined axial length range on the line segment is defined as a solid region ratio, a solid part summary diagram is a diagram in which the values ​​of the solid part ratios at each measurement point obtained by moving the line segment from the tip end of the protrusion toward the base end side at a predetermined pitch along the height direction of the protrusion in order, the solid part ratio being represented on the horizontal axis and the distance from the tip end in the height direction being represented as a measurement height on the vertical axis; an average of the solid part ratios at each measurement point obtained from a plurality of the cross sections is represented as an average solid part ratio, and the solid part summary diagram in which the average solid part ratio is plotted is represented as an average solid part summary diagram; in the average solid part summary diagram, a position where the average solid part ratio is 0 is represented as the tip end on the diagram, and a position where the average solid part ratio, plotted in order from the tip end side to the base end side, first exceeds 0.98 is represented as the base end on the diagram; and when the distance from the tip end on the diagram to the base end on the diagram is represented as the average maximum height of the protrusions, the average maximum height of the protrusions is 0.08% or more of the outer diameter of the insert member, in the average solid part summary diagram, in a range from the central position of the average maximum height of the protrusions to the tip end on the diagram, the sum of the average solid part ratios excluding the position of the tip end on the diagram is greater than the sum of the average solid part ratios in a range from the central position of the average maximum height of the protrusions to the base end on the diagram, excluding the position of the base end on the diagram.

2. The insert member for a rotating electrical machine according to claim 1, wherein the average maximum height of said protrusions is within the range of 0.08% to 1% of the outer diameter of said insert member.

3. An insert member for a rotating electric machine as described in claim 1 or 2, wherein two or more measurement points are plotted on the average solid part summary diagram, and the two or more measurement points are included within a range in which the difference in the average solid part ratios of the two or more measurement points is 0.10 or less and the difference in the measurement heights of the two or more measurement points is 0.05 mm or more.

4. An insert member for a rotating electric machine as claimed in any one of claims 1 to 3, wherein the plurality of average solid part ratios plotted on the average solid part summary chart have a maximum peak in the value of the average solid part ratio and a minimum peak in the value of the average solid part ratio, and the position of the maximum peak appears on the tip side of the chart relative to the position of the minimum peak.

5. The insert member for a rotating electrical machine according to claim 4, wherein in the average solid part summary diagram, the value of the average solid part ratio at the minimum peak is 0.08 or more.

6. The insert member for a rotating electric machine according to claim 4, wherein in the average solid part summary diagram, a difference between the average solid part ratio value at the maximum peak and the average solid part ratio value at the minimum peak is 0.02 or more and 0.20 or less.

7. The insert member for a rotating electrical machine according to claim 4, wherein in the average solid part summary diagram, the value of the average solid part ratio at the maximum peak is 0.50 or less.

8. The insert member for a rotating electric machine according to claim 1, wherein the protrusion is formed only on a partial area of ​​the outer peripheral surface of the insert member.

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