JP2020137176A - Motor case cylinder - Google Patents

Abstract

To improve cooling efficiency while suppressing die cutting resistance.SOLUTION: A casting cylinder in a motor case, has a cooling passage through which a refrigerant flows. The cooling passage has cast holes 21, 22 that are cast in a direction of a center line of the cylinder. A draft angle of an inner portion 23 of wall surfaces of the casting holes 21, 22 near an inner peripheral surface of the cylinder is smaller than a draft angle of an outer portion 24 near an outer peripheral surface of the cylinder. A cross-sectional shape when the casting holes 21, 22 are cut in a direction orthogonal to the center line direction has a long flat shape in a circumferential direction of the cylinder. A draft angle of the outer portion 24 of the wall surfaces of the casting holes 21, 22 is smaller than a draft angle of both end portions 25 in the circumferential direction of the cylinder on the wall surfaces of the casting holes 21, 22.SELECTED DRAWING: Figure 3

Description

The present invention relates to a cylinder of a motor case.

The motor is housed in the motor case. In order to cool the motor, a cooling passage is formed in the motor case. Refrigerant such as water flows through the cooling passage. In Patent Document 1 below, a cast hole is formed in the housing as a motor case as a passage for cooling. This cast hole extends along the center line direction of the housing (the axial direction of the motor shaft). The cast hole is a hole that does not penetrate. The cast hole is opened only in the first end of the first end and the second end of the housing. The cast holes are formed by casting from the first end of the housing. The wall surface (inner wall surface) of the cast hole has a draft. Therefore, the cast hole gradually approaches the inner peripheral surface of the housing from the closed end side toward the open end side. Therefore, the motor is cooled at a portion closer to the opening end of the casting hole than at a portion near the closing end of the casting hole.

Japanese Unexamined Patent Publication No. 2015-19494

An object of the present invention is to improve the cooling efficiency while suppressing the die punching resistance.

The cylinder of the motor case according to the present invention is a cylinder made by casting in the motor case, and has a cooling passage through which the refrigerant flows, and the cooling passage has a cast hole cast in the direction of the center line of the cylinder. The draft of the inner portion of the wall surface of the cast hole near the inner peripheral surface of the cylinder is smaller than the draft of the outer portion near the outer peripheral surface of the cylinder.

This cylinder has a cooling passage. The cooling passage has a cast hole cast in the direction of the center line of the cylinder. The draft of the inner part of the wall surface of the cast hole is small. Therefore, the housed motor can be efficiently cooled.

Also, when removing the mold from the cast cylinder, the cylinder tends to shrink inward due to the presence of the bore. Therefore, the die can be easily pulled out even if the draft of the inner portion of the wall surface of the cast hole is small. On the other hand, since the draft of the outer portion of the wall surface of the cast hole is larger than the draft of the inner portion, it is possible to prevent the die punching resistance, that is, the mold release resistance from becoming excessively large.

In particular, the draft of the inner portion of the wall surface of the cast hole is preferably 0. According to this configuration, the distance between the cast hole and the inner peripheral surface of the cylinder is constant along the direction of the center line of the cylinder. Therefore, the housed motor can be cooled in a well-balanced manner along the center line direction, and the cooling efficiency is improved. On the other hand, since the outer portion of the wall surface of the cast hole has a draft, an excessive increase in mold release resistance can be suppressed.

Further, the cross-sectional shape when the cast hole is cut in the direction orthogonal to the center line direction of the cylinder is a flat shape long in the circumferential direction of the cylinder, and the draft of the outer portion of the wall surface of the cast hole is cast. It is preferable that the wall surface of the hole is smaller than the draft at both ends in the circumferential direction of the cylinder. When the cross-sectional shape of the cast hole is flat as described above, the motor can be efficiently cooled. Due to the draft at both ends of the wall surface of the cast hole in the circumferential direction, the length of the cast hole in the circumferential direction gradually increases in the direction of casting. Further, the radial length of the cast hole gradually increases in the cast direction due to the draft of the outer portion of the wall surface of the cast hole. When the cross-sectional shape of the cast hole is flat, the circumferential length of the cast hole is longer than the radial length. If the draft of the outer portion of the wall surface of the cast hole and the draft of both end portions in the circumferential direction are the same, the amount of change in length due to the draft is the same in the radial direction and the circumferential direction. On the other hand, the original length is longer in the circumferential direction than in the radial direction. Therefore, the ratio of the amount of change in length due to the draft to the original length, that is, (the amount of change in length due to the draft) / (original length) is smaller in the circumferential direction than in the radial direction. Become. That is, the influence of the draft on the change in length is smaller in the circumferential direction than in the radial direction. Therefore, by making the draft of the outer portion relatively small and increasing the draft of both ends in the circumferential direction, it is possible to suppress the influence of the draft on the change in the cross-sectional shape of the cast hole. The draft of the wall surface can be secured. Therefore, the cooling efficiency can be comprehensively improved while suppressing the die punching resistance.

As described above, since the draft in the inner portion of the wall surface of the cast hole is smaller than the draft in the outer portion, it is possible to improve the cooling efficiency while suppressing the punching resistance of the die.

The figure which looked at the cylinder of the motor case in one Embodiment of this invention from the second end side toward the center line. A cross-sectional view taken along the line AA of FIG. (A) is an enlarged view of a main part of FIG. 2, and (b) is an enlarged view showing a cross-sectional shape of a cast hole. A development view of the cylinder cut along the circumferential direction. A development view of a cylinder having only a cast hole cast in one direction. The main part of the mold for casting the cylinder is shown, (a) is a front view of the bore forming part and the first cast hole forming part as viewed from the tip side toward the center line, and (b) is the second. The front view of the cast hole forming portion of the above viewed from the tip side toward the center line. The schematic which shows the casting method of the cylinder. (A) is a cross-sectional view of a main part of a cylinder according to another embodiment of the present invention, and (b) is a cross-sectional view of a main part showing a state of the cylinder before machining. The development view which cut the cylinder in the other embodiment of this invention along the circumferential direction. The development view corresponding to FIG. 9 which shows the processing method of the cylinder.

Hereinafter, the cylinder of the motor case and the casting method thereof according to the embodiment of the present invention will be described with reference to FIGS. 1 to 7. 1 and 2 show the cylinder 1 of the motor case according to the present embodiment. FIG. 1 is a view of the cylinder 1 as viewed from the second end 12 side thereof. Hereinafter, the direction of the center line of the cylinder 1 is simply referred to as the direction of the center line. The motor case includes a cylinder 1, a first cover 2, and a second cover 3. The cylinder 1 has a bore 10. The bore 10 penetrates the cylinder 1 in the center line direction. The cylinder 1 has an opening of a bore 10 at a first end portion 11 and a second end portion 12, respectively. The first cover 2 is screwed to the first end 11 of the cylinder 1. The first cover 2 covers the opening of the first end 11 of the cylinder 1. The second cover 3 is screwed to the second end 12 of the cylinder 1. The second cover 3 covers the opening of the second end 12 of the cylinder 1. The first cover 2 and the second cover 3 face each other in the center line direction. Screw bosses 13 for screwing the first and second covers 2 and 3 are provided on both ends 11 and 12 of the cylinder 1, respectively. The screw boss 13 locally bulges outward in the radial direction from the outer peripheral surface of the cylinder 1. The bore 10 does not have to be open to the first end 11 and the second end 12 of the cylinder 1, respectively, and is among the first end 11 and the second end 12. It may be open to only one side.

A motor (not shown) is housed in the motor case. The stator coil of the motor is fixed to the inner peripheral surface 14 of the cylinder 1. The stator coil is the main source of heat for the motor. The motor case has a cooling passage for cooling the motor. A refrigerant such as water flows through the cooling passage. The structure of the cooling passage may be various. For example, the cooling passage is formed in the cylinder 1 and both covers 2 and 3. The cylinder 1 has a plurality of through holes 20 as cooling passages. The through hole 20 extends along the direction of the center line and opens at both ends 11 and 12 of the cylinder 1, respectively. Both ends 11 and 12 of the cylinder 1 are planes orthogonal to the center line direction, respectively.

The cylinder 1 is made by casting and is manufactured by die casting. The both end portions 11 and 12 of the cylinder 1, the inner peripheral surface 14, and the screw holes 13a of the screw boss 13 are formed by machining such as cutting after casting. The inner peripheral surface 14 of the cylinder 1 has a straight shape having no gradient. The through hole 20 is a cast hole cast over the entire length of the cylinder 1. The cast holes are cast by a die at the time of casting. Therefore, the wall surface of the cast hole is formed by casting and is not machined. The plurality of through holes 20 are arranged at regular intervals in the circumferential direction of the cylinder 1. The number of through holes 20 is arbitrary, but is preferably an even number, which is 12 in the present embodiment. Of the plurality of through holes 20, half are the first cast holes 21 and the other half are the second cast holes 22. That is, the number of the first cast hole 21 and the second cast hole 22 are the same as each other, and the number is six each. The first cast hole 21 is cast from the first end 11 side of the cylinder 1. Therefore, the cross-sectional area of the first cast hole 21 gradually increases from the second end portion 12 of the cylinder 1 toward the first end portion 11. The second cast hole 22 is cast from the second end 12 side of the cylinder 1. Therefore, the cross-sectional area of the second cast hole 22 gradually increases from the first end portion 11 of the cylinder 1 toward the second end portion 12. The first cast hole 21 and the second cast hole 22 are alternately arranged in the circumferential direction of the cylinder 1. When the cylinder 1 is viewed from the second end 12 side, it is as shown in FIG. At the second end 12 of the cylinder 1, the opening of the first cast hole 21 is small and the opening of the second cast hole 22 is large. On the contrary, at the first end 11 of the cylinder 1, the opening of the first cast hole 21 is large and the opening of the second cast hole 22 is small.

The details of the cast holes 21 and 22 will be described. The first cast hole 21 and the second cast hole 22 are the same except that the casting direction is different. As shown in FIG. 3B, the cast holes 21 and 22 have a flat shape that is long in the circumferential direction of the cylinder 1. That is, the cross-sectional shape when the cast holes 21 and 22 are cut in the direction orthogonal to the center line direction of the cylinder 1 is a flat shape that is long in the circumferential direction of the cylinder 1 and short in the radial direction of the cylinder 1. The cast holes 21 and 22 have a track shape that is long in the circumferential direction of the cylinder 1. The cast holes 21 and 22 are curved in a cross-sectional arc shape along the circumferential direction of the cylinder 1 with the center line of the cylinder 1 as the center. The wall surface of the cast holes 21 and 22 has an inner portion 23 close to the inner peripheral surface 14 of the cylinder 1, an outer portion 24 close to the outer peripheral surface of the cylinder 1, and both end portions 25 in the circumferential direction of the cylinder 1. There is. The inner portion 23 and the outer portion 24 of the wall surface of the cast holes 21 and 22 are curved in an arc shape in a cross-sectional view toward the outer side in the radial direction along the circumferential direction of the cylinder 1. Of the wall surfaces of the cast holes 21 and 22, both end portions 25 in the circumferential direction of the cylinder 1 are hereinafter referred to as circumferential end portions 25 of the wall surfaces of the cast holes 21 and 22. Both end portions 25 in the circumferential direction of the wall surface of the cast holes 21 and 22 are semicircular in cross section.

The walls of the cast holes 21 and 22 have a draft. In the drawings, the draft is exaggerated. The draft is different for each part of the wall surface. The draft of the inner portion 23 of the wall surface is smaller than the draft of the outer portion 24 of the wall surface. The draft of the outer portion 24 of the wall surface is smaller than the draft of both end portions 25 in the circumferential direction of the wall surface. The drafts of both end portions 25 in the circumferential direction of the wall surface are equal to each other. That is, the draft of the wall surface increases in the order of the inner portion 23, the outer portion 24, and both end portions 25 in the circumferential direction. The draft of the inner portion 23 of the wall surface is preferably 0. When the draft of the inner portion 23 of the wall surface is 0, the inner portion 23 of the wall surface becomes parallel to the center line of the cylinder 1. As shown in FIG. 3A, the distance between the inner portion 23 of the wall surface and the inner peripheral surface 14 of the cylinder 1 is constant over the entire length of the cylinder 1. On the other hand, the outer portion 24 of the wall surface has a predetermined draft. The outer portion 24 of the wall surface gradually approaches the outer peripheral surface of the cylinder 1 in the direction of casting.

FIG. 4 shows a developed view of the cylinder 1 developed in the circumferential direction. As described above, the first cast hole 21 and the second cast hole 22 are provided alternately in the circumferential direction. The width of the first cast hole 21 gradually widens from the second end portion 12 of the cylinder 1 toward the first end portion 11. The width is a dimension in the circumferential direction. The width of the second cast hole 22 gradually widens from the first end portion 11 of the cylinder 1 toward the second end portion 12. The first cast-out hole 21 and the second cast-out hole 22 have the same draft gradients at both end portions 25 in the circumferential direction of the wall surfaces and are in opposite directions. Therefore, the circumferential distance between the adjacent first cast hole 21 and the second cast hole 22 is constant over the entire length of the cylinder 1.

FIG. 5 shows a cylinder 1 in which only a cast hole 21 in only one direction is formed. FIG. 5 shows a case where all the through holes are the first cast holes 21. In this case, the circumferential distance between the adjacent cast holes 21 and 21 gradually increases from the first end 11 to the second end 12 of the cylinder 1. That is, the width of the partition wall 26 between the cast holes 21 and 21 gradually increases from the first end 11 to the second end 12 of the cylinder 1. Therefore, waste meat is generated in the partition wall portion 26. On the other hand, when the first cast hole 21 and the second cast hole 22 are alternately provided in the circumferential direction as shown in FIG. 4, the first cast hole 21 and the second cast hole 22 are provided. The width of the partition wall portion 26 between the two and the partition wall portion 26 is constant over the entire length of the cylinder 1, and no waste is generated in the partition wall portion 26.

As shown in FIGS. 2 and 4, a part of the cooling passage is formed in both covers 2 and 3. The inner surface 2a of the first cover 2 facing the first end 11 of the cylinder 1 and the inner surface 3a of the second cover 3 facing the second end 12 of the cylinder 1 are respectively provided as cooling passages. The concave groove 30 is formed. The concave groove 30 extends along the circumferential direction of the cylinder 1. The concave groove 30 communicates the adjacent first cast hole 21 and the second cast hole 22. The direction in which the refrigerant flows through the first cast hole 21 and the second cast hole 22 may be any direction, but as an example, the direction of the refrigerant flow is indicated by an arrow in FIG. The direction of the refrigerant flow is, for example, the casting direction, but may be reversed. In this specific example, the refrigerant that has passed through the first cast hole 21 passes through the concave groove 30 of the first cover 2 and enters the adjacent second cast hole 22. The refrigerant that has passed through the second cast hole 22 passes through the concave groove 30 of the second cover 3 and enters the adjacent first cast hole 21. Although not shown, the motor case has an inlet and an outlet for the refrigerant. The inlet and outlet are provided on, for example, the first cover 2 and the second cover 3, but may be provided on the outer peripheral surface of the cylinder 1.

Next, the casting method of the cylinder 1 will be described. 6 and 7 show the main parts of the mold for casting the cylinder 1. At the time of casting, the center line of the cylinder 1 is set to, for example, the horizontal direction. The mold opening direction of the main mold (not shown) is, for example, the left-right direction with respect to the center line of the cylinder 1. The main type includes a fixed type and a movable type. The mold forms a bore forming portion 40 for forming the bore 10, a first cast hole forming portion 41 for forming the first cast hole 21, and a second cast hole 22. It is provided with a second cast hole forming portion 42 for the purpose. The bore forming portions 40 and the first and second cast hole forming portions 41 and 42 are driven along the center line direction. The moving directions of the bore forming portion 40 and the first and second cast hole forming portions 41 and 42 are orthogonal to the mold opening direction of the main mold. The first cast hole forming portion 41 and the second cast hole forming portion 42 are arranged so as to face each other on opposite sides of the cylinder 1 to be cast. The bore forming portion 40 is arranged with respect to the cylinder 1 on the same side as, for example, the first cast hole forming portion 41.

The bore forming portion 40 is a columnar shape having a predetermined center line. The outer peripheral surface of the bore forming portion 40 has a predetermined draft. The first cast hole forming portion 41 has a thin rod shape extending along the center line of the bore forming portion 40, and its cross-sectional shape is flat. The number of the first cast hole forming portions 41 corresponds to the number of the first cast holes 21. A total of six first cast hole forming portions 41 are arranged at regular angles on the radial outer side of the bore forming portion 40. The bore forming portion 40 and the first cast hole forming portion 41 are as shown in FIG. 6A when viewed from the tip end side of the bore forming portion 40. The plurality of first cast hole forming portions 41 are arranged around the bore forming portion 40 at regular angles. On the other hand, the second cast hole forming portion 42 has the same configuration as the first cast hole forming portion 41. A total of six second cast hole forming portions 42 are provided and are arranged at regular angles. The second cast hole forming portion 42 is as shown in FIG. 6 (b) when viewed from the tip side. The first cast hole forming portion 41 and the second cast hole forming portion 42 are displaced from each other by 30 degrees in the circumferential direction. FIG. 6A shows the second punched hole forming portion 42 by a chain double-dashed line. When the first cast hole forming portion 41 and the second cast hole forming portion 42 are close to each other in this way, the second cast hole forming portion 41 is between the adjacent first cast hole forming portions 41. The hole forming portion 42 is located, and the first cast hole forming portion 41 and the second cast hole forming portion 42 are arranged alternately in the circumferential direction.

The method of casting the cylinder 1 includes a mold release step of taking out the cast cylinder 1 from the mold. The mold release step includes a mold opening step of opening the main mold and a pulling step of pulling out the slide core from the cast cylinder 1. The above-mentioned bore forming portion 40 and the first and second cast hole forming portions 41 and 42 are slide cores. The drawing process is performed before the mold opening process. The drawing steps include a bore pulling step of pulling out the bore forming portion 40, a first hole punching step of pulling out the first cast hole forming portion 41, and a second hole punching of pulling out the second cast hole forming portion 42. Has a process. In the bore removing step, the bore forming portion 40 is driven in the first horizontal direction, and the bore forming portion 40 is pulled out in the first direction from the first end 11 side of the cylinder 1. In the first drilling step, the first punched hole forming portion 41 is driven in the same direction as the bore forming portion 40, and the first punched hole forming portion 41 is driven from the first end portion 11 side of the cylinder 1. Pull out in the first direction. In the second drilling step, the second cast hole forming portion 42 is driven in the second direction opposite to the bore forming portion 40 and the first punched hole forming portion 41 to drive the cylinder 1 to the first position. The second cast hole forming portion 42 is pulled out in the second direction from the second end portion 12 side.

An example of the process sequence is given. As shown in FIG. 7, first, the first hole punching step and the bore punching step are performed at the same time. That is, the bore forming portion 40 and the first cast hole forming portion 41 are simultaneously driven to move them together in the first direction and pulled out from the first end portion 11 side of the cylinder 1. After that, the second hole punching step is performed. Another example of process sequence is given. First, the bore removal process is performed. After that, the first hole punching step and the second hole punching step are performed at the same time. The first hole punching step and the second hole punching step may be performed with a time lag from each other. As described above, when the second hole punching step is performed after the bore punching step, the second cast hole forming portion 42 can be smoothly punched out from the cylinder 1. Since the resistance when pulling out the second casting hole forming portion 42 is reduced, it is possible to suppress an increase in the size of the casting apparatus.

As described above, in the cylinder 1 of the present embodiment, the first cast hole 21 cast from the first end 11 side and the second cast hole 22 cast from the second end 12 side. And have. Therefore, the cross-sectional area of the cooling passage in the cylinder 1 is less likely to change along the center line direction, and is less likely to be biased toward the first end portion 11 or toward the second end portion 12. Therefore, the cylinder 1 can be cooled in a well-balanced manner along the center line direction. In particular, if the first cast holes 21 and the second cast holes 22 are provided alternately in the circumferential direction of the cylinder 1, cooling variation along the circumferential direction can be suppressed, and the cylinder 1 can also be provided in the circumferential direction. It can be cooled in a well-balanced manner. Further, when the number of the first cast holes 21 and the second cast holes 22 is the same as each other, the total cross-sectional area of the cooling passage becomes constant along the center line direction. Therefore, the cylinder 1 can be uniformly cooled along the center line direction. The first cast hole 21 and the second cast hole 22 are along the circumferential direction, such that there are two first cast holes 21 and two second cast holes 22 next to them. Two of them may be arranged alternately. Further, only the first cast hole 21 may be formed in half of the entire circumference of the cylinder 1, and only the second cast hole 22 may be formed in the remaining half circumference. As described above, the arrangement mode of the first cast hole 21 and the second cast hole 22 may be various. However, if the number of the first cast holes 21 and the second cast holes 22 are the same and one is alternately arranged in the circumferential direction, the cross-sectional area of the cooling passage of the cylinder 1 as a whole becomes. It becomes constant over the entire length of the cylinder 1. Therefore, the cylinder 1 can be uniformly cooled over the entire length, and the cooling efficiency is excellent.

Further, the draft of the inner portion 23 of the wall surface of the cast holes 21 and 22 is smaller than the draft of the outer portion 24. Therefore, the motor can be cooled efficiently. In particular, when the draft of the inner portion 23 of the wall surface of the cast holes 21 and 22 is 0, the distance between the cast holes 21 and 22 and the inner peripheral surface 14 of the cylinder 1 is constant along the center line direction. It becomes. Therefore, it becomes easy to uniformly cool the motor along the center line direction, and the cooling efficiency is improved.

Further, when the cross-sectional shape of the cast holes 21 and 22 is flat, the motor can be efficiently cooled without excessively increasing the number of the cast holes 21 and 22. Due to the draft of both end portions 25 in the circumferential direction of the wall surface of the cast holes 21 and 22, the length of the cast holes 21 and 22 in the circumferential direction gradually increases in the direction of casting. That is, in the first cast hole 21, the length in the circumferential direction gradually increases toward the first end portion 11, and in the second cast hole 22, toward the second end portion 12. The length in the circumferential direction gradually increases. Further, due to the draft of the outer portion 24 of the wall surface of the cast holes 21 and 22, the radial length of the cast holes 21 and 22 gradually increases in the casting direction. That is, in the first cast hole 21, the length in the radial direction gradually increases toward the first end portion 11, and in the second cast hole 22, toward the second end portion 12. The length in the radial direction gradually increases. When the cross-sectional shape of the cast holes 21 and 22 is flat, the length of the cast holes 21 and 22 in the circumferential direction is longer than the length in the radial direction. When the draft of the outer portions 24 of the wall surface of the cast holes 21 and 22 and the draft of both end portions 25 in the circumferential direction are the same, the amount of change in length due to the draft is the same in the radial direction and the circumferential direction. On the other hand, the original length is longer in the circumferential direction than in the radial direction. Therefore, the ratio of the amount of change in length due to the draft to the original length, that is, (the amount of change in length due to the draft) / (original length) is smaller in the circumferential direction than in the radial direction. Become. That is, the influence of the draft on the change in length is smaller in the circumferential direction than in the radial direction. Therefore, by making the draft of the outer portion 24 relatively small and increasing the draft of both end portions 25 in the circumferential direction, it is possible to suppress the influence of the draft on the change in the cross-sectional shape of the cast holes 21 and 22. At the same time, it is possible to secure the draft of the wall surface. Therefore, the cooling efficiency can be comprehensively improved while suppressing the die punching resistance.

On the other hand, when the mold is pulled out from the cast cylinder 1, the cylinder 1 tends to shrink inward due to the presence of the bore 10. Therefore, even if the draft of the inner portion 23 of the wall surface of the cast holes 21 and 22 is small, the die can be easily punched. On the other hand, since the draft of the outer portion 24 of the wall surface of the cast holes 21 and 22 is larger than the draft of the inner portion 23, it is possible to suppress the die punching resistance, that is, the mold release resistance from becoming excessively large. it can. Further, when the draft of both end portions 25 in the circumferential direction of the wall surface of the cast holes 21 and 22 is larger than the draft of the outer portions 24 of the wall surface of the cast holes 21 and 22, the mold release resistance can be further suppressed.

In the present embodiment, the draft of the first cast hole 21 and the draft of the second cast hole 22 are the same, but they may be different from each other. For example, when the bore forming portion 40 and the first cast hole forming portion 41 are simultaneously pulled out in the same direction and then the second cast hole forming portion 42 is pulled out in the opposite direction, the first cast hole is pulled out. The draft of 21 may be larger than the draft of the second cast hole 22. The draft of the entire wall surface of the first cast hole 21 may be larger than the draft of the entire wall surface of the second cast hole 22, or the draft of the entire wall surface of the first cast hole 21. Only a part of them may be larger than the corresponding portion of the second cast hole 22. For example, the draft of the inner portion 23 of the wall surface of the first cast hole 21 may be larger than the draft of the inner portion 23 of the wall surface of the second cast hole 22.

Further, in the above embodiment, the case where the through hole 20 is the cast hole 21 and 22 over the entire length has been described, but most of the total length of the through hole 20 may be the cast hole 21 and 22. .. For example, even if most of the total length of the through hole 20 is a cast hole 21 and 22, and the rest of the total length of the through hole 20 is a cutting hole formed by machining such as cutting after casting. Good. As an example, the case of the first cast hole 21 will be described. As shown in FIG. 8A, the through hole 20 of the cylinder 1 is composed of a first cast hole 21 and a cutting hole 50. Of the total length of the through hole 20, most of the first end 11 side is the first cast hole 21, and the rest of the through hole 20 is the cutting hole 50. The wall surface of the cutting hole 50 is formed by cutting. As shown in FIG. 8B, a non-penetrating first cast hole 21 is formed by casting from the first end 11 side of the cylinder 1 during casting. The non-penetrating first cast hole 21 is formed in most of the total length of the cylinder 1 except for a part on the second end 12 side. In this state, the first cast hole 21 is open to the first end 11 of the cylinder 1, but not to the second end 12. After casting, the cutting hole 50 is formed coaxially with the first cast hole 21 by cutting from the second end 12 side of the cylinder 1 to complete the through hole 20. After casting, a cutting tool may be inserted into the first cast hole 21 to form the cutting hole 50 from the first end 11 side of the cylinder 1. The case of the first cast hole 21 has been described, but the same applies to the case of the second cast hole 22.

Further, a non-penetrating hole may be formed in the cylinder 1 as a cooling passage. For example, as shown in FIG. 9, a non-penetrating first cast hole 21 cast from the first end 11 side of the cylinder 1 and a non-penetrating non-penetrating hole 21 cast from the second end 12 side of the cylinder 1. The second cast holes 22 of the above can be arranged alternately in the circumferential direction. A communication hole 51 is provided in the partition wall portion 26 between the adjacent first cast hole 21 and the second cast hole 22. The communication holes 51 are provided in the partition wall portion 26 near the end on the back side of the first cast hole 21 and the partition wall portion 26 near the end on the back side of the second cast hole 22. The first cast hole 21 and the second cast hole 22 communicate with each other through the communication hole 51. FIG. 9 shows the flow of the refrigerant with arrows. In this case, the concave groove 30 is not formed in the first cover 2 and the second cover 3. The communication hole 51 is formed in the cylinder 1 after casting by machining such as cutting. That is, the communication hole 51 is formed by post-processing. A communication hole 51 can be formed in the partition wall portion 26 by forming a horizontal hole halfway from the outer peripheral surface of the cylinder 1 toward the inside in the radial direction at a portion indicated by a circle in FIG. The outer part of the lateral hole is sealed with a plug (not shown).

It should be noted that only the first cast hole 21 may be provided, or only the second cast hole 22 may be provided.

1 Cylinder 2 1st cover 2a Inner surface 3 2nd cover 3a Inner surface 10 Bore 11 1st end 12 2nd end 13 Screw boss 13a Screw hole 14 Inner peripheral surface 20 Through hole 21 1st cast hole 22 Second cast hole 23 Inner portion 24 Outer portion 25 Both end portions 26 Partition portion 30 Concave groove 40 Bore forming portion 41 First casting hole forming portion 42 Second casting hole forming portion 50 Cutting hole 51 Communication hole

Claims (3)

A cast cylinder in a motor case
The cooling passage has a cooling passage through which the refrigerant flows, and the cooling passage has a cast hole cast in the direction of the center line of the cylinder. The cylinder of the motor case, which is smaller than the draft of the outer part near the outer peripheral surface of the cylinder. The cylinder of the motor case according to claim 1, wherein the draft of the inner portion of the wall surface of the cast hole is 0. The cross-sectional shape when the cast hole is cut in the direction orthogonal to the center line direction of the cylinder is a flat shape that is long in the circumferential direction of the cylinder, and the draft of the outer part of the wall surface of the cast hole is the cast hole. The cylinder of the motor case according to claim 1 or 2, which is smaller than the draft of both ends of the cylinder in the circumferential direction of the wall surface.

Images