motor

Abstract

This step motor 10 comprises a first cup 53c, a first coil 52b, and a resin material 80. The first cup 53c has a cylindrical shape, has peripheral wall parts 53c, 53d on the outer peripheral side, and has a weir plate 53b on the inner peripheral side. The first coil 52b is assembled between the peripheral wall parts 53c, 53d and the wedge plate 53b. The resin material 80 is obtained by solidifying the molten resin YU so as to cover the first cup 53c and the first coil 52b. The peripheral wall parts 53c, 53d allow the molten resin YU to flow inward from spaces SP1, SP3 provided in first circumferential-direction end parts 53c1, 53d1 and spaces SP2, SP4 provided in second circumferential-direction end parts 53c2, 53d2. In the peripheral wall parts 53c, 53d, two through holes 53g are formed in the circumferential direction between the first circumferential-direction end parts 53c1, 53d1 and the second circumferential-direction end parts 53c2, 53d2.

Description

Motor

[0001] The technology disclosed in this specification relates to a motor.

[0002] Conventionally, as this type of technology, for example, the motor described in Patent Document 1 below can be cited. This motor includes a cup that is cylindrical, has a peripheral wall portion on the outer circumferential side and has magnetic pole teeth on the inner circumferential side, a coil assembled between the peripheral wall portion of the cup and the magnetic pole teeth of the cup, and a resin material that covers the cup and the coil. This resin material is obtained by filling molten resin so as to cover the cup and the coil through injection molding and then solidifying the molten resin.

[0003] Here, when filling the molten resin, at the peripheral wall portion of the cup, the molten resin flows into the inner side of the peripheral wall portion from between one circumferential end portion and the outer circumference of the coil, and also flows into the inner side of the peripheral wall portion from between the other circumferential end portion and the outer circumference of the coil. One through hole in the shape of a circular hole is formed in the peripheral wall portion of the cup. Therefore, the molten resin flows from the outer side to the inner side of the peripheral wall portion of the cup through the through hole. When the molten resin is thus filled between the entire inner side of the peripheral wall portion of the cup and the outer circumference of the coil and solidified, the resin material covering the cup and the coil is formed.

[0004] Japanese Unexamined Patent Publication No. 2021-151031

[0005] By the way, in the technology described in the above Patent Document 1, only one through hole is formed between the one circumferential end portion and the other circumferential end portion in the peripheral wall portion of the cup. Therefore, the circumferential distance from the one circumferential end portion of the peripheral wall portion of the cup to the through hole, or the circumferential distance from the other circumferential end portion of the peripheral wall portion of the cup to the through hole is long. As a result, it takes a longer time for the molten resin to fill the space between the entire inner side of the peripheral wall portion and the outer circumference of the coil, and there is a risk that the molten resin is filled when the temperature of the molten resin has decreased. As a result, the molten resin that is already solidifying is forced into the filling space, which may cause deformation or disconnection of the coil.

[0006] Accordingly, the present disclosure has been made to solve the above problems, and an object of the present disclosure is to provide a motor capable of suppressing deformation or disconnection of a coil.

[0007] To solve the above problems, one embodiment of the present disclosure is a motor comprising: a cylindrical cup having a peripheral wall on its outer circumference and magnetic pole teeth on its inner circumference; a coil assembled between the peripheral wall and the magnetic pole teeth; and a resin material in which molten resin has been solidified to cover the cup and the coil, wherein the peripheral wall allows the molten resin to flow into the inside of the peripheral wall from between one end portion in the circumferential direction and the outer circumference of the coil, allows the molten resin to flow into the inside of the peripheral wall from between the other end portion in the circumferential direction and the outer circumference of the coil, and has a plurality of through holes in the circumferential direction between the one end portion in the circumferential direction and the other end portion in the circumferential direction.

[0008] According to this embodiment, when forming the resin material covering the cup and the coil, molten resin flows in between one circumferential end of the cup's peripheral wall and the outer circumference of the coil, between the other circumferential end of the cup's peripheral wall and the outer circumference of the coil, and through multiple through holes in the cup's peripheral wall. At this time, since the peripheral wall has multiple through holes in the circumferential direction between one circumferential end and the other circumferential end, the circumferential distance from one circumferential end to the through hole, and the circumferential distance from the other circumferential end to the through hole are shorter compared to the case where the peripheral wall has one circumferential through hole. As a result, the time required for the molten resin to fill the space between the entire inside of the peripheral wall and the outer circumference of the coil can be shortened, and the molten resin can be avoided from being filled when its temperature has dropped. As a result, it is possible to avoid forcibly filling the space with molten resin that is solidifying, and the deformation or breakage of the coil can be suppressed.

[0009] In the above embodiment, it is preferable that each of the plurality of through holes is elongated.

[0010] According to this embodiment, since each of the multiple through holes is elongated, it is possible to avoid a reduction in the area of ​​the peripheral wall of the cup compared to, for example, when each of the multiple through holes is circular, thereby preventing a weakening of the motor's magnetic force.

[0011] In the above embodiment, it is preferable that each of the plurality of through holes has an elongated shape that is long in the axial direction of the cup.

[0012] In this embodiment, the direction of the motor's magnetic field is the radial direction of the cup. Therefore, if the through-hole is elongated in the axial direction of the cup, it can prevent the weakening of the motor's magnetic field without obstructing the direction of the motor's magnetic field, compared to, for example, an elongated through-hole that is elongated in the circumferential direction of the cup.

[0013] In the above embodiment, it is preferable that the plurality of through holes are provided at equal intervals in the circumferential direction between the circumferential end portion and the circumferential end portion of the circumferential wall.

[0014] In this embodiment, the circumferential distance from one end of the circumferential wall to the through hole, the circumferential distance from the other end to the through hole, and the circumferential distances between multiple through holes are all the same. Therefore, the time required for the molten resin to fill the entire inside of the circumferential wall can be minimized.

[0015] The motor of this disclosure can suppress deformation or breakage of the coil.

[0016] This is a side view showing an EGR valve incorporating a stepper motor. This is a cross-sectional view of the EGR valve shown in Figure 1. This is a side view of the coil stator shown in Figure 2. This is a cross-sectional view of the coil stator shown in Figure 3. This is a perspective view of the assembled sub-coil stator shown in Figure 4. This is an exploded perspective view of the assembled sub-coil stator shown in Figure 5. This is a diagram showing the path through which molten resin is filled into each peripheral wall portion of the cup of the embodiment. This is a perspective view of a comparative assembled sub-coil stator. This is a diagram showing the path through which molten resin is filled into each peripheral wall portion of the cup of the comparative embodiment.

[0017] Hereinafter, embodiments of the motor described herein will be described in detail with reference to the drawings. The motor of the embodiment is a stepper motor 10, which is incorporated into the EGR valve 1 shown in Figure 1.

[0018] [Overview of the EGR valve] Figure 1 is a side view of the EGR valve 1 of an embodiment, and Figure 2 is a cross-sectional view of the EGR valve 1 shown in Figure 1. The EGR valve 1, when in the open state, is used to recirculate a portion of the exhaust gas (EGR gas) from the engine (not shown) to the engine cylinder. As shown in Figures 1 and 2, the EGR valve 1 comprises a housing 2, a valve stem 3, a valve seat 4, a valve body 5, and a stepper motor 10.

[0019] As shown in Figure 2, the housing 2 is assembled so that the valve stem 3 passes through its interior and has a passage 2a through which EGR gas flows. The passage 2a has an inlet 2b through which EGR gas flows in and an outlet 2c through which EGR gas is discharged. The passage 2a is divided by the valve seat 4 into a first passage 2d on the inlet 2b side and a second passage 2e on the outlet 2c side.

[0020] The valve stem 3 extends long in the axial direction O1, and the valve body 5 is fixed to one end 3a (the lower end in Figure 2). The other end 3b (the upper end in Figure 2) of the valve stem 3 is located inside the stepper motor 10. The valve stem 3 is assembled to the housing 2 so as to be able to reciprocate in the axial direction O1.

[0021] The valve seat 4 is provided in the housing 2 so that the valve body 5 can be seated on it. As shown in Figure 2, when the valve body 5 is seated on the valve seat 4, the EGR valve 1 is in a closed state and EGR gas cannot flow from the first flow path 2d to the second flow path 2e.

[0022] The valve body 5 is formed in a substantially disc shape and is reciprocally movable in the axial direction O1 together with the valve stem 3. Therefore, the valve body 5 and the valve stem 3 can be moved from the position shown in Figure 2 to one side of the axial direction O1 (the lower side in Figure 2) by the operation of the stepper motor 10. In this way, the valve body 5 moves away from the valve seat 4, causing the EGR valve 1 to open, and allowing the EGR gas to flow from the first passage 2d to the second passage 2e.

[0023] [About the configuration of the stepper motor] As shown in Figure 2, the stepper motor 10 is assembled to the housing 2 and is used to reciprocate the valve stem 3 in the axial direction O1. This stepper motor 10 includes a magnet rotor 20 and a coil stator 30. Note that the axial direction O1 of the valve stem 3 is the same as the axial direction O1 of each component of the stepper motor 10, which will be described later.

[0024] As shown in Figure 2, the magnetic rotor 20 comprises a rotor body 21 and a cylindrical magnet 22 integrally provided on the outside of the rotor body 21. The rotor body 21 is assembled to the coil stator 30 so as to be rotatable around the axial direction O1 via a radial bearing 23. The rotor body 21 is also screwed onto the other end 3b of the valve stem 3. The magnet 22 supports the intermediate portion 3c of the valve stem 3 so as to be movable in the axial direction O1 via a radial bearing 24 and a thrust bearing 25. In this way, by the rotation of the rotor body 21 and the magnet 22, the valve stem 3 can move in the axial direction O1 without rotating around the axial direction O1.

[0025] The coil stator 30, when combined with the magnet rotor 20, constitutes the stepper motor 10. Figure 3 is a perspective view of the coil stator 30, and Figure 4 is a cross-sectional view of the coil stator 30 shown in Figure 3. As shown in Figure 4, the coil stator 30 comprises a sub-coil stator 40, a cap 70, and a resin material 80. Figure 5 shows a perspective view of the sub-coil stator 40, and Figure 6 shows an exploded perspective view of the sub-coil stator 40.

[0026] As shown in Figures 4 and 5, the assembled subcoil stator 40 consists of a first subcoil stator 50 and a second subcoil stator 60 arranged coaxially with each other. In Figure 4, the first subcoil stator 50 is located on the lower side of Figure 4, and the second subcoil stator 60 is located on the upper side of Figure 4. In Figure 5, the first subcoil stator 50 is located on the upper side of Figure 5, and the second subcoil stator 60 is located on the lower side of Figure 5.

[0027] As shown in Figure 6, the first subcoil stator 50 includes a first coil bobbin 51, a first stator 52 made of metal, and a first cup 53 made of metal. As shown in Figures 4 and 6, the first coil bobbin 51 includes an annular first bobbin 51a and a first coil 51b wound around the outer circumference of the first bobbin 51a. The first coil bobbin 51 is provided with a terminal portion 51c extending radially outward. A magnetic field is generated when current is supplied to the first coil 51b via the terminal portion 51c from a driver (not shown).

[0028] As shown in Figure 6, the first stator 52 is positioned on one side of the first coil bobbin 51 in the axial direction O1 (the lower side in Figure 6). The first stator 52 has a substantially annular base plate 52a and a plurality of wedge-shaped wedge plates 52b. On the inner circumference of the base plate 52a, the plurality of wedge plates 52b extend at equal intervals in the circumferential direction to the other side of the axial direction O1 (the upper side in Figure 6).

[0029] As shown in Figure 6, the first cup 53 is cylindrical and is positioned on the other side of the first coil bobbin 51 in the axial direction O1 (upper side in Figure 6). The first cup 53 has a substantially annular bottom plate 53a, a plurality of wedge-shaped wedge plates 53b, and two circumferential wall portions 53c and 53d that form arc-shaped side walls. On the inner circumference of the bottom plate 53a, the plurality of wedge plates 53b extend at equal intervals in the circumferential direction to one side in the axial direction O1 (lower side in Figure 6). The "wedge plates 53b" correspond to an example of "magnetic pole teeth" in this disclosed technology.

[0030] The peripheral wall portions 53c and 53d are positioned radially outward from the first coil 51b. In other words, the first coil 51b is positioned between the peripheral wall portions 53c and 53d provided on the outer circumference of the first cup 53 and the wedge plates 53b provided on the inner circumference of the first cup 53. A first opening 53e and a second opening 53f are formed between the peripheral wall portion 53c and the peripheral wall portion 53d in the circumferential direction. The first opening 53e is for allowing the terminal portion 51c of the first coil bobbin 51 to protrude radially outward.

[0031] Thus, as shown in Figure 6, the first sub-coil stator 50 is constructed by assembling the first cup 53 and the first stator 52 coaxially sandwiched between the first coil bobbin 51. In this first sub-coil stator 50, as shown in Figure 5, the wedge plates 53b of the first cup 53 and the wedge plates 52b of the first stator 52 are arranged alternately in the circumferential direction, radially inward from the first coil 51b.

[0032] As shown in Figure 6, the second sub-coil stator 60 includes a second coil bobbin 61, a second stator 62 made of metal, and a second cup 63 made of metal. As shown in Figures 4 and 6, the second coil bobbin 61 includes an annular second bobbin 61a and a second coil 61b wound around the outer circumference of the second bobbin 61a. The second coil bobbin 61 is provided with a terminal portion 61c extending radially outward. A magnetic field is generated when current is supplied to the second coil 61b via the terminal portion 61c from a driver (not shown).

[0033] As shown in Figure 6, the second stator 62 is positioned on the other side of the axial direction O1 (upper side in Figure 6) relative to the second coil bobbin 61. The second stator 62 has a substantially annular base plate 62a and a plurality of wedge-shaped wedge plates 62b. On the inner circumference of the base plate 62a, the plurality of wedge plates 62b extend at equal intervals in the circumferential direction to one side of the axial direction O1 (lower side in Figure 6).

[0034] As shown in Figure 6, the second cup 63 is cylindrical and is positioned on one side of the second coil bobbin 61 in the axial direction O1 (the lower side in Figure 6). The second cup 63 has a substantially annular bottom plate 63a, a plurality of wedge-shaped wedge plates 63b, and two circumferential wall portions 63c and 63d that form arc-shaped side walls. On the inner circumference of the bottom plate 63a, the plurality of wedge plates 63b extend at equal intervals in the circumferential direction to the other side in the axial direction O1 (the upper side in Figure 6).

[0035] The peripheral wall portions 63c and 63d are positioned radially outward from the second coil 61b. In other words, the second coil 61b is positioned between the peripheral wall portions 63c and 63d provided on the outer circumference of the second cup 63 and the wedge plates 63b provided on the inner circumference of the second cup 63. A first opening 63e and a second opening 63f are formed between the peripheral wall portion 63c and the peripheral wall portion 63d in the circumferential direction. The first opening 63e is for allowing the terminal portion 61c of the second coil bobbin 61 to protrude radially outward.

[0036] Thus, as shown in Figure 6, the second sub-coil stator 60 is constructed by assembling the second cup 63 and the second stator 62 coaxially sandwiched between the second coil bobbin 61. In this second sub-coil stator 60, the wedge plates 63b of the second cup 63 and the wedge plates 62b of the second stator 62 are arranged alternately in the circumferential direction, radially inward from the second coil 61b.

[0037] The cap 70 is formed from metal in a hat shape and is placed on top of the second sub-coil stator 60, as shown in Figures 4 and 6. As shown in Figure 4, the resin material 80 covers the outside of each cup 53, 63, the outside of each stator 52, 62, and the outside of the cap 70, with the assembled sub-coil stator 40 and the cap 70 stacked coaxially. The resin material 80 is also formed in the radial closed spaces between the peripheral walls 53c, 53d, 63c, 63d of each cup 53, 63 and each coil 51b, 61b. In this way, each coil bobbin 51, 61, each stator 52, 62, and each cup 53, 63 are resin-molded with the resin material 80.

[0038] The resin material 80 is formed by injection molding. Specifically, when injection molding is performed, the assembled sub-coil stator 40 and cap 70 are mounted in a mold (not shown). Subsequently, molten resin YU is supplied to the mold from above the center position of the cap 70 as shown in Figure 4. As a result, the molten resin YU fills each closed space formed between the assembled sub-coil stator 40 and cap 70 and the mold. Then, as the filled molten resin YU cools and solidifies, the resin material 80 (coil stator 30) shown in Figures 3 and 4 is formed.

[0039] Incidentally, as shown in Figures 5 and 6, in the assembled sub-coil stator 40, each peripheral wall portion 53c, 53d of the first cup 53 is provided with two through holes 53g, and each peripheral wall portion 63c, 63d of the second cup 63 is provided with two through holes 63g. Each through hole 53g, 63g penetrates each peripheral wall portion 53c, 53d, 63c, 63d in the radial direction. Therefore, when the injection molding described above is performed, as shown in Figure 7, the molten resin YU is supplied from the outside to the inside of each peripheral wall portion 53c, 53d, 63c, 63d through each through hole 53g, 63g, and the molten resin is filled between the inside of each peripheral wall portion 53c, 53d, 63c, 63d and the outer circumference of the coils 51b, 61b.

[0040] Furthermore, as shown in Figure 7, a space SP1 is formed between the circumferential end portions 53c1, 63c1 of the peripheral walls 53c, 63c (the clockwise end portions in Figure 7) and the outer circumference of the coils 51b, 61b. Also, a space SP2 is formed between the other circumferential end portions 53c2, 63c2 of the peripheral walls 53c, 63c (the counterclockwise end portions in Figure 7) and the outer circumference of the coils 51b, 61b. Similarly, a space SP3 is formed between the circumferential end portions 53d1, 63d1 of the peripheral walls 53d, 63d (the clockwise end portions in Figure 7) and the outer circumference of the coils 51b, 61b. Furthermore, a space SP4 is formed between the other circumferential end portions 53d2, 63d2 of the peripheral walls 53d, 63d (the counterclockwise end portions in Figure 7) and the outer circumference of the coils 51b, 61b. Therefore, when the injection molding described above is performed, the molten resin YU passes through each space SP1, SP2, SP3, SP4, filling the space between the inside of each peripheral wall portion 53c, 53d, 63c, 63d and the outer circumference of the coils 51b, 61b. In the following, since the effects of each peripheral wall portion 53c, 53d of the first cup 53 are the same as those of each peripheral wall portion 63c, 63d of the second cup 63, only the effects of each peripheral wall portion 53c, 53d of the first cup 53 will be described as representative.

[0041] Figure 8 shows a comparative configuration of the assembled subcoil stator 40X, and Figure 9 shows the paths through which molten resin is filled into each peripheral wall portion 93c, 93d of the comparative configuration. In the comparative configuration, as shown in Figures 8 and 9, only one through-hole 93g is formed in each peripheral wall portion 93c, 93d. Each through-hole 93g is circular in shape, and the area of ​​the through-hole 93g is larger than the areas of the through-holes 53g, 63g of the embodiment. Each through-hole 93g is located in the peripheral wall portion 93c, 93d, closer to the circumferential end portion 93c1, 93d1 than to the other circumferential end portion 93c2, 93d2. The other configurations of the comparative configuration are the same as those of the embodiment described above. Therefore, in Figure 9, the same reference numerals are used for corresponding parts, and detailed explanations are omitted.

[0042] In the comparative configuration, when injection molding is performed, as shown in Figure 9, the molten resin YU is supplied from the outside to the inside of each peripheral wall portion 93c, 93d through each through hole 93g. The molten resin YU is also supplied to the inside of the peripheral wall portion 93c from the space SP1 between the circumferential end portion 93c1 of the peripheral wall portion 93c and the coil 51b, and from the space SP2 between the circumferential end portion 93c2 of the peripheral wall portion 93c and the coil 51b. The molten resin YU is also supplied to the inside of the peripheral wall portion 93d from the space SP3 between the circumferential end portion 93d1 of the peripheral wall portion 93d and the coil 51b, and from the space SP4 between the circumferential end portion 93d2 of the peripheral wall portion 93d and the coil 51b. As a result, the molten resin fills the entire inside of each peripheral wall portion 93c, 93d and the outer circumference of the coil 51b.

[0043] This comparative configuration has the following problems. Specifically, as shown in Figure 9, since only one through-hole 93g is formed in each of the peripheral wall portions 93c and 93d, the circumferential distance M1 from the other circumferential end portion 93c2 of the peripheral wall portion 93c to the through-hole 93g is long, and the circumferential distance M2 from the other circumferential end portion 93d2 of the peripheral wall portion 93d to the through-hole 93g is also long. Therefore, when injection molding is performed, it takes a long time for the molten resin YU moving towards the other circumferential end portions 93c2 and 93d2 through the through-hole 93g inside the peripheral wall portions 93c and 93d, and the molten resin YU moving towards the through-hole 93g from the spaces SP2 and SP4 to merge. Consequently, the time it takes for the molten resin YU to fill the entire inside of the peripheral wall portions 93c and 93d and the outer circumference of the coil 51b becomes long, and there is a risk that the molten resin YU will be filled at a lower temperature. As a result, the molten resin YU, which was solidifying, was forcibly filled in, potentially causing the coil 51b to deform or break.

[0044] In contrast to this, in the present embodiment, as shown in FIG. 7, two through-holes 53g are formed in the circumferential direction in the peripheral wall portion 53c between one circumferential end portion 53c1 and the other circumferential end portion 53c2. Therefore, a circumferential distance L1 from the one circumferential end portion 53c1 to the through-hole 53g, a circumferential distance L2 from the other circumferential end portion 53c2 to the through-hole 53g, and a circumferential distance L3 between adjacent through-holes 53g are each shorter than the distance M1 (see FIG. 9) in the comparative example described above. Similarly, two through-holes 53g are formed in the circumferential direction in the peripheral wall portion 53d between one circumferential end portion 53d1 and the other circumferential end portion 53d2. Therefore, a circumferential distance L4 from the one circumferential end portion 53d1 to the through-hole 53g, a circumferential distance L5 from the other circumferential end portion 53d2 to the through-hole 53g, and a circumferential distance L6 between adjacent through-holes 53g are each shorter than the distance M2 (see FIG. 9) in the comparative example described above.

[0045] Thereby, in the present embodiment, when injection molding is performed, the time required for the molten resin YU to fill the entire space between the entire inner side of the peripheral wall portions 53c, 53d and the outer periphery of the coil 51b can be made shorter than the time required for the molten resin YU to fill the entire space between the entire inner side of the peripheral wall portions 93c, 93d and the outer periphery of the coil 51b in the comparative example. Therefore, it is possible to avoid filling the space between the inner side of the peripheral wall portions 53c, 53d and the outer periphery of the coil 51b with molten resin when the temperature of the molten resin YU has decreased. As a result, forced filling of the molten resin YU that is already solidifying can be avoided, and deformation or disconnection of the coil 51b can be suppressed.

[0046] Furthermore, in the present embodiment, as shown in FIGS. 5 and 6, each through-hole 53g formed in the peripheral wall portions 53c and 53d has an oblong shape. Here, the oblong shape is a shape in which one end of two parallel straight lines are connected to one end and the other end of a semicircle, while the other end of the two parallel straight lines are connected to one end and the other end of another semicircle, and the length of the two parallel straight lines is longer than the distance between the two parallel straight lines. The "oblong shape" corresponds to an example of the "elongated hole shape" in the disclosed technology. The total area of the two through-holes 53g (see FIG. 5) of the present embodiment is configured to be substantially the same as the area of one through-hole 93g (see FIG. 8) of the comparative example.

[0047] Thus, even when two through-holes 53g are respectively provided in the peripheral wall portions 53c and 53d, the area of the peripheral wall portions 53c and 53d is not reduced compared to the area of the peripheral wall portion 93d in the comparative example. That is, if two circular through-holes 93g of the type shown in the comparative example are provided in the peripheral wall portions 53c and 53d, the area of the peripheral wall portions 53c and 53d, which are formed of a metal plate, will decrease, which may potentially weaken the magnetic force of the stepping motor 10. Therefore, in the present embodiment, each through-hole 53g formed in the peripheral wall portions 53c and 53d is formed into an oval shape instead of a circular shape, thereby avoiding a reduction in the area of the peripheral wall portions 53c and 53d formed of the metal plate and preventing the magnetic force of the stepping motor 10 from weakening.

[0048] Furthermore, in the present embodiment, as shown in FIGS. 5 and 6, each through-hole 53g formed in the peripheral wall portions 53c and 53d is an oval shape that is elongated in the axial direction O1. In other words, each through-hole 53g is an oval shape whose long axis extends along the axial direction O1. This configuration is based on the following reasons. In the stepping motor 10, the direction of the magnetic field is radial relative to the cup 53. Therefore, if oval through-holes elongated in the circumferential direction are formed in the peripheral wall portions 53c and 53d, the magnetic field direction will be obstructed. That is, when each through-hole is an oval shape elongated in the circumferential direction, the formation of the magnetic circuit is obstructed, which may potentially weaken the magnetic force of the stepping motor 10. Therefore, in the present embodiment, each through-hole 53g formed in the peripheral wall portions 53c and 53d is formed into an oval shape elongated in the axial direction O1, so that the magnetic field direction is not obstructed, and the magnetic force of the stepping motor 10 can be prevented from weakening. In other words, by forming two through-holes 53g spaced apart in the circumferential direction into an oval shape elongated in the axial direction O1, the fluidity of the molten resin is improved while suppressing a decrease in the torque of the stepping motor 10.

[0049] Furthermore, in this embodiment, as shown in Figure 7, the two through holes 53g are provided at equal intervals in the circumferential direction between the circumferential end portions 53c1, 53d1 and the other circumferential end portions 53c2, 53d2 of the circumferential wall portions 53c, 53d. Therefore, in the circumferential wall portions 53c, 53d, the circumferential distances L1, L4 from the circumferential end portions 53c1, 53d1 to the through holes 53g, the circumferential distances L2, L5 from the other circumferential end portions 53c2, 53d2 to the through holes 53g, and the circumferential distances L3, L6 between the two through holes 53g are all the same. In other words, it avoids the occurrence of areas where one of the circumferential distances L1 to L6 becomes longer, resulting in a longer time for the molten resin to reach that area. In this way, the time required for the molten resin to fill the entire inside of each circumferential wall portion 93c, 93d and the outer circumference of the coil 51b during injection molding can be minimized.

[0050] Furthermore, this disclosed technology is not limited to the embodiments described above, and it may be implemented by appropriately modifying, adding, deleting, or combining parts of the configuration without departing from the spirit of the disclosed technology.

[0051] In the above embodiment, as shown in Figure 7, two through holes 53g, 63g were formed in the circumferential direction in each of the peripheral wall portions 53c, 63c, 53d, 63d. However, three or more through holes may be formed in the circumferential direction in each of the peripheral wall portions 53c, 63c, 53d, 63d. However, since the torque of the step motor 10 decreases when the area of ​​each peripheral wall portion 53c, 63c, 53d, 63d, which is a metal plate, decreases, it is preferable that the number of through holes not be unnecessarily large (for example, three or fewer).

[0052] In the above embodiment, as shown in Figures 5 and 6, each through-hole 53g, 63g was oval-shaped. However, the shape of each through-hole is not limited to an oval shape and can be changed as appropriate. For example, the shape of each through-hole may be an ellipse that is long in the axial direction O1. An "ellipse shape" corresponds to an example of an "oval shape" in this disclosed technology. The shape of each through-hole may also be circular, an oval that is long in the circumferential direction, or an oval that extends axially O1 and obliquely in the circumferential direction. However, from the viewpoint of achieving both a through-hole shape that does not easily obstruct the magnetic field direction and a through-hole shape that does not easily reduce the area of ​​the circumferential wall portions 53c, 53d, 63c, 63d, the shape of each through-hole is preferably an elongated hole shape (oval shape, ellipse shape) that is long in the axial direction O1.

[0053] In the above embodiment, as shown in Figure 7, each cup 53, 63 has openings 53e, 53f and openings 53f, 63f, resulting in two peripheral wall portions 53c, 53d, 63c, 63d. However, for example, each cup 53, 63 may have only openings 53e, 63e, resulting in only one peripheral wall portion. Even in this case, in order to improve the fluidity of the molten resin, it is preferable to have multiple through holes formed in the circumferential direction between one end portion and the other end portion of the peripheral wall portion. Alternatively, each cup 53, 63 may have three or more openings, resulting in three or more peripheral wall portions. Even in this case, in order to improve the fluidity of the molten resin, it is preferable to have multiple through holes formed in the circumferential direction between one end portion and the other end portion of each peripheral wall portion.

[0054] In the above embodiment, as shown in Figure 7, in one peripheral wall portion 53c, the multiple through holes 53g were provided at equal intervals in the circumferential direction between one circumferential end portion 53c1 and the other circumferential end portion 53c2. That is, the multiple through holes 53g were provided such that the circumferential distance L1 from the circumferential end portion 53c1 to the through hole 53g, the circumferential distance L2 from the other circumferential end portion 53c2 to the through hole 53g, and the circumferential distance L3 between the through holes 53g were all the same. However, in one peripheral wall portion 53c, the multiple through holes 53g may not be provided at equal intervals in the circumferential direction between the circumferential end portion 53c1 and the other circumferential end portion 53c2. However, in this case, from the viewpoint of improving the fluidity of the molten resin compared to the case where one through hole is provided in one peripheral wall portion 53c, it is preferable that the circumferential distance L1 from one circumferential end portion 53c1 to the through hole 53g, the circumferential distance L2 from the other circumferential end portion 53c2 to the through hole 53g, and the circumferential distance L3 between the through holes 53g be less than half of the circumferential distance of the peripheral wall portion 53c (the circumferential distance from one circumferential end portion 53c1 to the other circumferential end portion 53c2). Note that the above-described modification is not limited to the peripheral wall portion 53c, but may also be applied to peripheral wall portions 53d, 63c, and 63d.

[0055] In the above embodiment, the motor was a stepper motor 10 used in the EGR valve 1. However, the motor is not limited to a stepper motor 10 and may be of other types. For example, the motor may be a brushless motor used in an electric pump.

[0056] 1…EGR valve 10…Stepper motor 20…Magnet rotor 30…Coil stator 40…Assembled sub-coil stator 50, 60…First sub-coil stator, second sub-coil stator 51, 61…First coil bobbin, second coil bobbin 51a, 61a…First bobbin, second bobbin 51b, 61b…First coil, second coil 52, 62…First stator, second stator 52b, 62b…Wedge plate 53, 63…First cup, second cup 53b, 63b…Wedge plate 53c, 53d, 63c, 63d…Circumferential wall portion 53c1, 53d1, 63c1, 63d1…Circumferential one end portion 53c2, 53d2, 63c2, 63d2…Circumferential other end portion 53g, 63g…Through hole 80... Resin material O1... Shaft center YU... Molten resin

Claims

1. A motor comprising: a cylindrical cup having a peripheral wall on its outer circumference and magnetic pole teeth on its inner circumference; a coil assembled between the peripheral wall and the magnetic pole teeth; and a resin material in which molten resin has been solidified to cover the cup and the coil, wherein the peripheral wall is such that the molten resin can flow into the inside of the peripheral wall from between one end portion in the circumferential direction and the outer circumference of the coil, the molten resin can flow into the inside of the peripheral wall from between the other end portion in the circumferential direction and the outer circumference of the coil, and has a plurality of through holes in the circumferential direction between the one end portion in the circumferential direction and the other end portion in the circumferential direction.

2. A motor according to claim 1, characterized in that each of the plurality of through holes is elongated.

3. A motor according to claim 2, characterized in that each of the plurality of through holes is an elongated hole shape that is elongated in the axial direction of the cup.

4. A motor according to any one of claims 1 to 3, characterized in that the plurality of through holes are provided at equal intervals in the circumferential direction between one end portion in the circumferential direction and the other end portion in the circumferential direction of the peripheral wall.

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