JPH09238459A - Stepping motor - Google Patents

Abstract

PROBLEM TO BE SOLVED: To bring a yoke into tight contact with an excitation coil without the necessity of the control of the outside dimensions of a stator. SOLUTION: A lower case 22 and stators (4 and 5) and (11 and 12) are integrally molded to obtain a stator molding 80. Excitation coils 6 and 13 are wound on the outer circumferences of the pole parts of the stators (4 and 5) and (11 and 12) and then a yoke 41 which is formed into a U-shape is fitted into a spacing between the stators (4 and 5) and (11 and 12) from the side of the stator molding 80 so as to be attached and detached freely and the tips of the yoke 41 are bent along the excitation coils 6 and 13. Further, bearing parts 81 and 82 which support a minute hand shaft 33 and a rotor magnet 1 so as to rotate freely and a terminal holding part 84 which holds a terminal 85 are provided in the lower case 22 integrally.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a step motor using a permanent magnet, and more particularly to a step motor using a crystal oscillator, a motor for driving an EGR (exhaust gas recirculation) valve, a geared motor, and the like. Related step motor.

[0002]

2. Description of the Related Art In recent years, so-called quartz timepieces using a quartz oscillator have become widespread, and those installed in places that are out of reach such as station premises and high wall surfaces can adjust the time quickly and remotely by remote control. I am trying to be able to do it accurately. As a motor applicable to such a remotely controllable quartz timepiece, a two-phase excitation type step motor capable of rotating in forward and reverse directions by controlling the phase of a signal supplied to an excitation coil is known.

10 to 13 show a conventional example of such a two-phase excitation step motor. FIG. 10 is a sectional view of the step motor, FIG. 11 is a perspective view of a rotor magnet and a stator assembly, and FIG. And FIG. 13 is a diagram showing an excitation pattern. In these figures, 20 is a case for a timepiece, which is composed of an upper case 21 and a lower case 22.
A pair of stator assemblies 2, 3, a minute hand shaft 33, an hour hand shaft 36,
The gear transmission mechanism 23 and the like are stored.

As shown in FIG. 11, the rotor magnet 1 has magnetic poles N1, N2, N3, S1 and S2 of 3 to 6 poles on the outer circumference.
, S3 are alternately magnetized at equal intervals in the circumferential direction, and are rotatably supported by bearing projections 24, 25 integrally provided on the upper case 21 and the lower case 22. Further, a gear 26 is integrally provided on the upper portion of the rotor magnet 1, and the rotation of the gear 26 is controlled by the gear 30.
-Rotary gear 30a-gear 31-gear 31a-gear 32 to the minute hand shaft 33, and further rotation of the gear 30 is the gear 30
It is transmitted to the hour hand shaft 36 via a-gear 31-gear 31a-gear 32-gear 32a-gear 34-gear 34a-gear 35, respectively. The hour hand shaft 36 integrally has a gear 35, and is rotatably fitted on the minute hand shaft 33.

The upper stator assembly 2 is composed of a pair of stators 4, 5 and an exciting coil 6 for exciting these stators 4, 5. The pair of stators 4 and 5 are
The stators 4 and 5 are arranged in the same plane orthogonal to the axis of the rotor magnet 1 to form a magnetic circuit through the rotor magnet 1. The stators 4 and 5 are formed in a U-shape in a plan view and are symmetrical with each other. Are arranged to face each other, and one ends thereof face each other with the rotor magnet 1 sandwiched therebetween to form stator magnetic pole portions 7 and 8, respectively, and the other ends 9 and 10 are wound with the exciting coil 6. The bobbin 40 is made of a non-magnetic material such as synthetic resin. The facing surfaces of the stator magnetic pole portions 7 and 8 are formed in a semicircular concave curved surface over a range of about 180 ° so as to face the outer circumference of the rotor magnet 1 with an appropriate gap G.

The lower stator assembly 3 has the same structure as the upper stator 2 described above, and thus includes a pair of stators 11 and 12 and an exciting coil 13, and the exciting coil 13 is the exciting coil 6. And the stator 2 on the upper side so as to be located on the opposite side with the rotor magnet 1 interposed therebetween, and are arranged in a state of being 180 ° out of phase with each other in the circumferential direction of the rotor magnet 1. The ends of the stators 11 and 12 that face each other with the rotor magnet 1 sandwiched between them are stator magnetic poles 14 and 15.
Are formed respectively. An intermediate plate 16 made of a non-magnetic material is interposed between the upper stator assembly 2 and the lower stator assembly 3 in order to prevent magnetic interference between these two assemblies.

In such a structure, the exciting coil 6,
When 13 is energized and the stators 4, 5, 11, and 12 are excited in two phases, four excitation patterns, that is, (N, S, N,
S), (N, S, S, N), (S, N, S, N) and (S, N, N, S) are obtained, and when these excitation patterns are continuously changed in this order. , Rotor magnet 1
The rotor magnet 1 rotates in a predetermined direction at a constant speed by the magnetic action between the stator and the stators 4, 5, 11, and 12. Then, the rotation of the rotor magnet 1 is decelerated and transmitted to the minute hand shaft 33 and the hour hand shaft 36 via the gear transmission mechanism 23, and the minute hand shaft 33 rotates once per hour and the hour hand shaft 3
Rotate 6 once every 12 hours. Further, when the cycle of the excitation pattern is changed in the opposite direction to the above, the rotor magnet 1 rotates in the opposite direction to the above, whereby the time can be adjusted. 11 and 12 show the excitation pattern (N, S, N, S), and FIG. 13 shows the excitation pattern (N, S, S, N).

FIG. 14 is a diagram showing an exhaust gas recirculation system for an automobile engine, and FIG. 15 is a sectional view of a step motor used in the system. Exhaust gas recirculation system
An exhaust pipe 51 and an intake pipe 52 connected to the engine body 50 are connected by an exhaust gas recirculation flow passage 53, and an exhaust gas inlet 53a of the recirculation flow passage 53 is controlled to be opened and closed by a control valve 55 driven by a step motor 54. By doing so, the amount of exhaust gas flowing from the exhaust pipe 51 into the recirculation flow passage 53 is adjusted.

The control valve 55 is provided in a housing 56 integrally provided on the outer circumference of the exhaust pipe 51 so as to be movable back and forth.
7 and a plug 5 integrally provided at the tip of the valve shaft 57
8 and a compression coil spring 59 for urging the valve shaft 57 in the direction in which the plug 58 closes the exhaust gas inlet 53a. The recirculation flow path 5 is provided on the peripheral surface of the housing 56.
A discharge port 53b communicating with the No. 3 is formed.

The step motor 54 is formed by molding, and is disposed in a motor housing 61. The stator assembly 62 is fitted in the stator assembly 62 with a proper gap and is rotatable by a bearing 63. It has a rotor magnet 60 supported axially. The stator assembly 62 includes four stators 62a, each including two stators 62a to 62a.
It is composed of 62d. These stators 62a-6
Of the 2d, the outer periphery of the outer stator 62a, 62d is integrally provided with a folded portion 72 bent in the direction of the other pair of stators 62b, 62c, respectively. , 6
It is magnetically coupled with 2c. Each exciting coil 64 is
The stators 62a and 62b, 62c and 62d wound around the bobbin 74 and constituting each set of stator assemblies are respectively housed and connected to the terminals 70. In manufacturing such a stator assembly 62, each stator assembly is formed separately and overlapped, and is integrally formed with the motor housing 61. That is, the exciting coil 64 wound around the bobbin 74, the terminal 70, and the stator 62b are integrally molded with the synthetic resin 73, and the stator 62a is fitted thereto to form one stator assembly. Further, the exciting coil 64 wound around the bobbin 74, the terminal 70, and the stator 62c are integrally molded with the synthetic resin 73, and the stator 62d is fitted thereto to form the other stator assembly. A motor housing 61 and a stator assembly 62 are integrally formed by stacking these stator assemblies with an intermediate plate 71 made of aluminum or the like being sandwiched therebetween, and loading and molding them in a mold.

The rotor magnet 60 is formed into a cylindrical body, and the center hole 60a thereof has a plug 5 of the valve shaft 57.
The end portion on the side opposite to the 8 side is slidably and non-rotatably fitted in the direction of the axis K2. That is, the valve shaft 57 is
An oil metal 67 provided in the motor housing 61 holds the intermediate portion slidably and prevented from rotating, and a male screw 68 is formed on the outer periphery of the rotor side end portion. The male screw 68 is screwed into a screw body 69 fixed in the center hole 60a of the rotor magnet 60.
The screw body 69 is formed of a synthetic resin into a cylindrical body,
A female screw 69a with which the male screw 68 is screwed is formed on the inner peripheral surface. Therefore, when the rotation of the rotor magnet 60 is transmitted to the male screw 68 via the screw body 69, the valve shaft 57 moves forward and backward in the axial direction, and when it moves forward, the plug 58 closes the inflow port 53a.

In the conventional step motor shown in FIGS. 10 to 13, the exciting coil 6 (1
3 is also the same) and a plate-shaped yoke 41 is disposed inside, and the other end portions 9, 1 of the stators 4, 5 are arranged in the bobbin 40.
Since 0 is inserted and these other ends are magnetically connected by the yoke 41, there is a problem that the assembly work of the stator assemblies 2 and 3 is complicated. Also, bobbin 40
Since the terminals 42 to which the ends of the exciting coil 6 are connected are provided at both ends of the stator, the upper and lower stator assemblies 2, 3
In the above, there is a problem in that the connection of the external wiring cannot be concentrated in one place because the terminals 42 are taken out upside down and the positions are 180 degrees out of phase with each other around the rotor magnet 1. Further, since the bobbin 40 is required, there is a problem that the number of parts is large and the assembling work is complicated.

A conventional step motor 54 shown in FIG.
, One of the two stators (62b,
62c), the exciting coil 64 and the terminal 70 are molded, and then the other pair of stators (62a, 62d) is attached to form each set of stator assemblies, and then these stator assemblies must be superposed. Therefore, there has been a problem that the management of the part size and the number of assembling steps increase.
Further, there is a problem that the assembly work of the stator is troublesome and the number of parts is increased because the bobbin 74 is used as in the above-described conventional step motor.

Therefore, in order to solve such a problem,
There is proposed a step motor in which an exciting coil is wound around a magnetic pole portion of a stator assembly through a mold resin without using a bobbin (Japanese Patent Laid-Open No. 61-2176, hereinafter referred to as prior invention). That is, in this step motor, four stators, each set of two, are molded to form a stator assembly, and the surface portion of the stator assembly of each set on which the exciting coil is wound and closely covered is covered with a molding resin.
This stator assembly is fitted and inserted in a yoke that also serves as a frame and is formed in a cylindrical shape.

[0015]

The above-mentioned prior invention has the advantages that it is easy to manufacture, does not require a bobbin, and can reduce the number of parts, but it is possible to match the outer circumferences of all four stators. Since it is difficult, when the stator assembly is inserted into the yoke that also serves as the frame, there is a problem that a gap is generated between the stator and the yoke.
That is, as shown in FIG. 5, each set of stators 4 and 5, 1
1 and 12 are superposed with the magnetic pole portion (110) shifted by a half pitch. Therefore, the four stators 4, 5, 11,
12 has a slightly different shape, and has two upper and lower stators 4, 1
Since 2 is the same, the magnetic poles are made to face each other by pressing with the same mold. In other words, one is inverted. Since the intermediate stators 5 and 11 are the same and different from the stators 4 and 5, they are pressed by another same mold, and one of them is also inverted. Therefore, depending on the dimensional accuracy of each mold, the stators 4, 12 and 5,
If the outer diameters of 11 are different or are eccentric, when the four stators 4, 5, 11, 12 are overlapped with the centers of the magnetic pole portions aligned, a step is formed on the outer circumference of each stator. Therefore, when the stator assembly is inserted into the yoke, a gap is created between each stator and the yoke, and as a result, the magnetic efficiency is reduced.

Further, such a step also occurs when four stators are molded. That is, when molded, the mold resin contracts in the axial direction and radial direction of the stator when cooled. This shrinkage is not constant in each part of the mold resin, but varies depending on the wall thickness, shape and the like. In this case, since the direction of displacement of each stator due to radial contraction differs for each stator, a step occurs on the outer circumference of each stator when contracting in the radial direction. As described above, in the above-described prior invention, the step due to the outer diameter dimension of the stator, the eccentricity, and the like, and the step due to the shrinkage of the mold resin after molding are significant problems, but it is extremely difficult to eliminate such a step in manufacturing. It was difficult.

The present invention has been made to solve the above-mentioned conventional problems. The purpose of the present invention is to eliminate the need to control the outer diameter of the stator and to keep the yoke in close contact with the exciting coil. It is to provide a step motor capable of operating. Another object of the present invention is to provide a step motor in which the yoke can be securely attached to the stator assembly by one operation.

[0018]

In order to achieve the above object, the step motor according to the present invention is formed by molding and integrally forming four stators, each of which has two sets as one set and whose axes are aligned. The stator mold, the exciting coil wound around the magnetic poles of the stators of each set, the rotor magnet rotatably inserted in the stator, and the U-shaped stator magnet are detachable between the stators. A yoke is fitted to cover the exciting coil, and a tip end portion of the yoke is bent along the peripheral surface of the exciting coil. Further, the present invention is characterized in that a surface portion of the stator of each set, to which the exciting coils are closely contacted, is covered with a resin coating portion. Further, the step motor according to the present invention is characterized in that the stator mold and the lower case or the upper case are integrally provided. Further, the step motor according to the present invention is characterized in that the stator mold is integrally provided with a bearing portion or a bearing holding portion for rotatably supporting the rotor magnet. Further, the step motor according to the present invention is characterized in that the stator mold is integrally provided with a terminal holding portion that holds a plurality of terminals to which the ends of the exciting coil are connected. Further, the step motor according to the present invention is characterized in that a stator mold is provided with a bearing portion that rotatably supports at least one of the rotation transmission gear wheel trains. Further, the step motor according to the present invention is characterized in that the stator mold or the stator and the yoke are provided with an engaging portion for engaging with each other and positioning the yoke.

In the present invention, the four stators are molded to form one piece by forming a stator mold. The yoke is fitted between the stators of each set.
Therefore, even if a step is formed on the outer circumference of the stator, there is no problem. The resin coating portion that covers the surface portion of the stator that is closely contacted with the exciting coil functions as a bobbin. The stator mold and the lower case or the upper case are integrated into one component. Therefore, the number of parts can be reduced. The bearing portion or the bearing holding portion of the stator mold rotatably supports the rotor magnet. Also, the terminal holding part of the stator mold is
A plurality of terminals to which the ends of the exciting coil are connected are centrally held at one place. Therefore, it is easy to connect the external wiring from one direction. The bearing portion of the lower case or the upper case rotatably supports at least one of the rotation transmission gear trains. The yoke is removably attached to the stator and forms a magnetic circuit with the stator. The engaging portion detachably locks the yoke to the stator.

[0020]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below based on an embodiment shown in the drawings. 1 to 7 are views showing an embodiment in which the present invention is applied to a step motor for a timepiece,
1 is an external perspective view of the motor, FIG. 2 is a plan view of the motor, FIG. 3 is a perspective view of a stator mold with an upper case removed, FIG. 4 is a sectional view taken along line IV-IV of FIG. 2, and FIG. 6A and 6B are a developed view and a plan view of a bent state of the yoke, and FIG. 7 is a view for explaining attachment of the yoke. Note that the same components as those shown in the section of the prior art are denoted by the same reference numerals, and description thereof will be omitted as appropriate. In these figures, the stators 4, 5, 11, and 12 that form each set of stator assemblies 2 and 3 are integrally formed with the lower case 22 by molding to form a stator mold 80. Therefore, the stators 4 and 5, 11 and 12 forming each stator assembly 2 and 3 are
The surface where the exciting coils 6 and 13 come into close contact with each other, that is, the surface that faces the outer surface of the pole tooth 110 (described later) forming each magnetic pole portion in the axial direction, as shown in FIG. It is covered with a resin coating portion) 111a.

The lower case 22 is composed of an upper plate portion 22a and a lower plate portion 22b which face each other in parallel in the vertical direction. The minute hand shaft 33 and the lower end of the shaft 1A of the rotor magnet 1 are provided on the upper surfaces of the both plate portions 22a and 22b. Bearing portions 81 and 82 that rotatably support the portion 91b are integrally provided. The bearing portion 81 of the minute hand shaft 33 is a protrusion having a circular cross section, and the bearing portion 82 of the rotor magnet 1 is a circular recess. Furthermore, the upper plate portion 22a is integrally provided with a terminal holding portion 84, a plurality of positioning pins 86 for positioning and fixing the upper case 21, and a screw mounting portion 88 (FIG. 3). The terminal holding portion 84 extends rearward of the upper plate portion 22a, and centrally holds a plurality of terminals 85 to which the ends of the exciting coils 6 and 13 are connected. Each terminal 85
Has a lower end portion which penetrates a small hole 87 formed in the lower plate portion 22b and extends below the lower case 22 and is electrically connected to a drive circuit of a printed circuit board (not shown). in this way,
If a plurality of terminals 85 are provided centrally at one location, the work of connecting the external wiring is easy.

In the rotor magnet 1, as in the conventional rotor magnet described above, 5 to 10 magnetic poles (N1 to N5, S1 to S5) are alternately magnetized on the outer periphery at equal intervals in the circumferential direction. The stator mold 80 is rotatably inserted into the center hole 90 (FIG. 4) with the center of the stator mold 80 and the center of the shaft 1A aligned.
An upper end portion 91a of the shaft 1A is rotatably supported by a cylindrical bearing portion 92 projecting from the inner surface of the upper case 21, and a lower end portion 91b is supported by the bearing portion 82. The rotation of the rotor magnet 1 is decelerated by a gear 94 provided on the upper portion of the shaft 1A and a gear 95 meshing with the gear 94 and transmitted to the minute hand shaft 33. Further, the rotation of the minute hand shaft 33 is performed by the gear 96-the reverse gear (reduction gear) of the day.
It is transmitted to the hour hand shaft 36 via 97-gear 98-gear 99. The hour hand shaft 36 is rotatably fitted to the minute hand shaft 33, and an upper end portion of the hour hand shaft 36 projects upward from the hole 100 of the upper case 21 together with the minute hand shaft 33. Hinoura Gear 97
A shaft 101 vertically extending from the inner surface of the upper case 21 is rotatably supported, and a lower surface of the lower case 22 is supported by an upper surface of an upper plate portion 22a. And
The upper case 21 is fixed to the upper surface of the upper plate portion 22a by a plurality of setscrews 103, so that the rotor magnet 1, the minute hand shaft 33, the hour hand shaft 36, the gears 94, 95, 97, 99 ... Etc. In addition,
At the outer periphery of the lower end portion of the hour hand shaft 36, a timepiece spring 104 is attached which presses the minute hand shaft 33 and the hour hand shaft 36 downward by being pressed against the inner surface of the upper case 21 and prevents rattling in the thrust direction. Has been done.

In FIG. 5, the pair of stators 4 and 5, 11 and 12 forming the upper stator assembly 2 and the lower stator assembly 3, respectively, are formed in the substantially same disk shape as described above. Five pole teeth 110 forming a stator magnetic pole portion are equally distributed in the circumferential direction on the inner peripheral side thereof, and are bent downward and upward at substantially right angles so as to face each other. The pole tooth 110 has a triangular shape, and the inner side surface thereof forms the inner wall surface of the central hole 90 (FIG. 4) of the stator mold 80. The pole tooth 110 faces the outer circumference of the rotor magnet 1 with a predetermined gap, and faces the outer side of the stator. The exciting coils 6 and 13 are directly wound via the resin coating portion 111a formed by molding the mold 80. Therefore, the resin coating portion 111a functions as a bobbin. These exciting coils 6 and 13 are wound after the stators 4, 5, 11 and 12 and the lower case 22 are molded.

A pair of positioning recesses 112 are provided 180 ° out of phase with each other on the outer peripheral edge of each of the stators 4, 5, 11, and 12, and these positioning recesses 112 are provided.
When the four stators are overlapped with each other, the pole teeth 110 of each stator assembly 2 and 3 of each set are located between the pole teeth of the mating stator. In other words, the stators 4, 5, 11 and 12 are superposed with the magnetic teeth 110 shifted by a half pitch. Then, the stators 5 and 11 are overlapped back to back. Furthermore, each stator 4, 5,
An arbitrary number of insertion holes 113 are formed in each of 11 and 12, and the insertion holes 113 are filled with the molding resin 111 to increase the coupling strength between the stators 5 and 11 and the stators 4 and 12 and the lower case 22. There is. A yoke 41 forming a magnetic circuit with the stators 4, 5, 11, and 12 is detachably fitted from the side of the stator mold 80 to cover the exciting coils 6 and 13. In addition, such stators 4, 5, 11, 12
Are overlapped with the pole teeth 110 shifted by a half pitch, the stators 4, 12 are of the same type, and the stators 5, 1
1 is press-molded by another same mold.

As shown in FIG. 6 (a), the yoke 41 connects two elongated plate portions 41a and 41b which are formed in parallel by punching a metal plate and the like, and both end portions of these plate portions are connected to each other. Consists of parts 41c and 41d,
(B) As shown in the figure, it is bent into a substantially U shape, and the plate portions 41a and 41b are fitted between the stators 4 and 5, 11 and 12 of each set. The arc portion of the yoke 41 has substantially the same size as the outer shape of the exciting coils 6 and 13. Further, both ends of each of the connecting portions 41c and 41d are appropriately dimensionally protruded above and below the yoke 41, so that the yoke 4
Engagement portions 115 for positioning 1 with respect to the stators 4, 5, 11, 12 are formed.

In the yoke 41 as described above, the plate portions 41a and 41b constitute the upper stator assembly 2 and the lower stator assembly 3 from the side of the lower case 22 as described above. The exciting coils 6 and 13 are fitted in between and cover each other. At this time, the upper engaging portion 115 engages with the positioning recess 112 of the stator 4, and the lower engaging portion 115 engages with the positioning recess 112 of the stator 12,
The connecting portions 41c and 41d engage with the positioning recesses 112 of the stators 5 and 11, respectively, to positionally lock the yoke 41 with respect to the stator assemblies 2 and 3. Then, the linearly formed tip ends of the plate portions 41a and 41b are inwardly moved with the vicinity of the connecting portions 41c and 41d as a fulcrum in order to ensure magnetic coupling with the stators 4, 5, 11, and 12. Can be folded. In this case, each plate part 41a, 4
Since 1b is fitted between the stators 4 and 5, 11 and 12 of each set, it is possible to closely contact the exciting coils 6 and 13. In FIG. 3, reference numeral 116 is a cutout recess for avoiding the engaging portion 115 of the yoke.

In the step motor having such a structure, the stators 4, 5, 11 and 12 and the lower case 22 which constitute the pair of stator assemblies 2 and 3 are integrally formed by molding to form the resin coating portion 111a. Since the exciting coils 6 and 13 are directly wound around the outer circumference, the bobbin that has been conventionally required is not necessary, and the number of parts can be reduced. Particularly, in the present invention, after the exciting coils 6 and 13 are wound around the magnetic pole portions of the stators 4 and 5 and 11 and 12 of the stator assemblies 2 and 3, respectively, the plate portions 4 of the yoke 41 are wound.
Since the stators 1a and 41b are fitted from the side of the stator mold 80 between the stators of the stator assemblies 2 and 3 of each set, the stators 4, 5, 11 and 12 are subject to manufacturing errors, eccentricity, shrinkage of the molding resin and the like. There is no problem even if there is a step on the outer periphery of the stator, and it is easier to control the outer diameter dimension of the stator as compared with the above-mentioned prior invention. Further, the engaging portion 115 and the engaging portion 1
When the yoke 4 is engaged with the positioning recess 112,
Since it suffices to engage 1 with the stator mold 80, the work of attaching the yoke 41 is easy, and the yoke 41 can be securely fixed at a predetermined position. Further, the yoke 41 is connected to the exciting coils 6 and 13
Can be close to. Further, the lower case 22 has a minute hand shaft 33 and bearing portions 81, 82 of the rotor magnet 1.
Since the terminal holding portion 84 of the terminal 85 is integrally provided, the number of parts can be further reduced. Furthermore, since the plurality of terminals 85 to which the exciting coils 6 and 13 are connected are concentrated in the terminal holding portion 84, the work of connecting the external wiring is easy.

In the above embodiment, the stators 4, 5, 11, 12 and the lower case 22 are integrally formed by molding to form the stator mold 80. However, the present invention is not limited to this, and the stator is located on the upper case 21 side. In the case of the above, the stators 4, 5, 11 and 12 and the upper case 21 may be integrally formed by molding to form a stator mold.

FIG. 8 is a sectional view showing an embodiment in which the present invention is applied to an EGR valve step motor. In this embodiment, the four stators 62a to 62d, the terminals 70, and the metal tubular body 134, which are stacked and aligned with their axes aligned, are molded and integrated with a synthetic resin to form a stator mold 130. The outer circumferences of the magnetic poles of the pair of stators 62a and 62b, 62c and 62d and the surfaces opposed to each other in the axial direction are covered with the covering portion 111a of the molding resin 111, and the exciting coil 6 is provided on the outer circumferences of the magnetic poles.
4, 64 are wound respectively. In addition, the yoke 132 is provided between the stators 62a and 62b, 62c and 62d of each set.
Are engaged with each other, and an engaging portion (not shown) and a recess provided on the stator 132 side are engaged with each other so as to be detachably fixed. Such a yoke 132 is exactly the same as the yoke 41 (see FIG. 6) shown in the above-described embodiment, and is formed in a U shape, and its tip is bent along the outer circumference of the exciting coil 64.

The cylindrical portion 111b provided at the lower end portion of the mold resin 111 and the cylindrical body 134 respectively form bearing holding portions, and these hold bearings 63 that axially support the rotor magnet 60, respectively. An intermediate portion of the valve shaft 57, which is disposed in the rotor magnet 60 so as to be movable back and forth, is rotatably supported by an oil metal 67 provided in the housing 56. The valve shaft 57 is biased toward the rotor 60 by the compression coil spring 133. This is to remove the backlash in the engagement between the valve shaft 57 and the screw body 69. A pin 135 is driven into the intermediate portion of the valve shaft 57, and one end of the compression coil spring 133 is pressed against the pin 135 via a washer. The oil metal 67 is prevented from rotating by the pin 136. The bearing 63 on the upper side in the drawing that supports the rotor 60 and the housing 5
A conical coil spring 137 for pressing the bearing 63 and the rotor 60 is elastically mounted between the bearing 6 and the bearing 6. The terminal 7
0 is connected to a printed board 139, and a lead wire 140 is connected to the printed board 139 via a connector 141. Since other configurations are substantially the same as those of the conventional step motor shown in FIG. 15, the same components are designated by the same reference numerals, and the description thereof will be omitted.

Even in such a structure, the yoke 132
Are fitted between the stators 62a and 62b and 62c and 62d of each set, the same effect as that of the above-described embodiment can be obtained.

FIG. 9 is a sectional view showing an embodiment in which the present invention is applied to a geared motor. This geared motor 1
Reference numeral 50 includes a rotor magnet 152 and a stator mold 153 arranged in a motor housing 151, and a rotation transmission gear train wheel 155 arranged in a gear housing 154 to reduce the rotation of the rotor magnet 152.

The rotor magnet 152 is formed in a cylindrical shape and attached to the rotary shaft 156, and forms a slight gap, that is, a magnetic gap, between the outer peripheral surface and the stator mold 153. The stator mold 153 includes four stators 161a to 161d, which form a set of two and are arranged in a stack with their axes aligned with each other, and these stators 16
1a to 161d are molded and integrally bonded to each other by a molding resin 111. At the center of the upper surface of the mold resin 111, a through hole 163 through which the rotary shaft 156 passes is formed and a bearing 164 is provided. Further, the outer surfaces of the stators 161a and 161b and 161c and 161d of the respective sets, which are opposed to each other in the magnetic pole portion outer circumference and the axial direction, are covered with the resin coating portion 111a, and the excitation coils 165 and 165 wound around the magnetic pole portion outer circumferences.
A yoke 166 is attached to the outside of the. This yoke 166 is the yoke 4 shown in the above-mentioned embodiment.
1 (see FIG. 6) and 132 (see FIG. 8) are formed in a U shape, and each set of stators 161a and 161b, 161
They are fitted between c and 161d, respectively, and detachably fixed by the engagement of a not-shown engaging portion and a recess. In addition,
The exciting coil 165 is connected to the terminal 167.

The rotary shaft 156 is the motor housing 1
Bearing 168 provided on the inner bottom surface of 54 and stator mold 1
The bearing 164 provided on the mold resin 111 of 53 is rotatably supported. Further, one end of the rotary shaft 156 penetrates through the through hole 163 of the mold resin 111 and projects into the motor housing 154, and one gear 170 forming the rotation transmission gear wheel train 155 is fixed to the projecting end. Has been done. The rotation transmission gear train 155 is
The gear 170 and the rotation of the gear 170 are controlled by the output shaft 17
The gears 173-177 which transmit to 2 are provided.

Even in such a structure, the same effect as that of the above-described embodiment can be obtained.

[0036]

As described above, in the step motor according to the present invention, two stators are formed as a set by combining four stators, one of which is a set of two, and the stators are stacked and arranged with their axes aligned. An exciting coil is wound around the magnetic poles of the stators of the set, a rotor magnet is rotatably inserted into the stator, and a yoke formed in a U shape is detachably fitted between the stators of the set to perform the excitation. Since the coil is covered, the work of attaching the yoke is easy, manufacturing error,
Even if a step is formed on the outer circumference of the stator due to eccentricity, shrinkage of the molding resin, or the like, no inconvenience occurs, the outer diameter dimension of the stator can be easily controlled, and the yoke can be closely attached to the exciting coil. Further, since the yoke is fitted between the stators of each set, the area where the broken surface of the yoke comes into contact with the stator increases, and the variation in magnetic efficiency can be reduced.

Further, according to the present invention, since the stator mold and the lower case or the upper case are integrally provided, the number of parts and the number of assembling steps can be reduced. Also,
According to the present invention, since the bearing portion or the bearing holding portion that rotatably supports the rotor magnet is integrally provided on the stator mold, the number of parts and the number of assembling steps can be reduced also from this point, and the assembling workability can be improved. it can. Further, according to the present invention, since the terminal holding portion for holding a plurality of terminals to which the ends of the exciting coil are connected is integrally provided in the stator mold, it is not necessary to provide any separate member, and the number of parts and the number of assembling steps are further increased. Can be reduced. Further, a plurality of terminals can be concentratedly arranged in the terminal holding portion, which facilitates wiring connection work.

Further, in the present invention, since the lower case or the upper case is provided with the bearing portion for rotatably supporting at least one of the rotation transmission gear wheel trains, it is not necessary to provide a bearing as a separate member, and the number of parts is reduced. And the number of assembly steps can be reduced. Further, according to the present invention, since the stator mold or the engaging portion for engaging the stator and the yoke with each other and positioning the yoke is provided, the yoke can be securely fixed at a predetermined position, and the magnetic coupling with the stator is good. Is.

[Brief description of drawings]

FIG. 1 is an external perspective view of a step motor according to the present invention.

FIG. 2 is a plan view of the motor.

FIG. 3 is a perspective view of a stator mold with an upper case removed.

FIG. 4 is a sectional view taken along line IV-IV of FIG. 2;

FIG. 5 is a perspective view of a stator.

6A and 6B are a developed view and a plan view of a bent state of a yoke.

FIG. 7 is a diagram for explaining attachment of a yoke.

FIG. 8 is a sectional view showing an embodiment in which the present invention is applied to an EGR valve step motor.

FIG. 9 is a cross-sectional view showing an embodiment in which the present invention is applied to a geared motor.

FIG. 10 is a cross-sectional view showing a conventional example of a step motor.

FIG. 11 is a perspective view of a rotor magnet and a stator assembly.

FIG. 12 is a diagram showing an excitation pattern.

FIG. 13 is a diagram showing an excitation pattern.

FIG. 14 is a diagram showing an exhaust gas recirculation system for an automobile engine.

FIG. 15 is a cross-sectional view of a step motor used in the system.

[Explanation of symbols]

1 ... Rotor magnet, 2, 3 ... Stator assembly, 4,
5 ... Stator, 6 ... Exciting coil, 7, 8 ... Stator magnetic pole part, 11, 12 ... Stator, 13 ... Exciting coil, 14,
15 ... Stator magnetic pole part, 20 ... Case, 21 ... Upper case, 22 ... Lower case, 33 ... Minute hand shaft, 36 ... Hour hand shaft, 41 ... Yoke, 60 ... Rotor magnet, 62a ...
62d ... Stator, 64 ... Excitation coil, 81, 82 ... Bearing part, 84 ... Terminal holding part, 85 ... Terminal, 110 ... Pole tooth (stator magnetic pole part), 111 ... Mold resin, 111a
... Resin coating portion, 112 ... Positioning concave portion, 132 ... Yoke, 115 ... Engaging portion, 130 ... Stator mold, 15
2 ... Rotor magnet, 153 ... Stator mold, 1
55 ... Rotation transmission gear train, 161a to 161d ... Stator, 166 ... Yoke, 167 ... Terminal.

Claims (7)

[Claims] 1. A stator mold formed by molding and integrating four stators, two of which are set as one set and which are arranged in layers with their axes aligned, and an exciting coil wound around the outer circumference of the magnetic pole portion of each set of stators. And a rotor magnet rotatably inserted in the stator and a stator formed in a U shape and detachably fitted between the stators of the respective sets to cover the exciting coil, and a tip end portion of the exciting coil surrounds the peripheral surface of the exciting coil. A step motor having a yoke that can be bent along the step motor. 2. The step motor according to claim 1, wherein a surface portion of the stator of each set, to which the exciting coils are brought into close contact, is covered with a resin coating portion. 3. The step motor according to claim 1, wherein the stator mold and the lower case or the upper case are integrally provided. 4. The step motor according to claim 1, wherein a bearing portion or a bearing holding portion for rotatably supporting a rotor magnet is integrally provided on the stator mold. 5. The step motor according to claim 1, 2, 3 or 4, wherein a terminal holding portion for holding a plurality of terminals to which the ends of the exciting coil are connected is integrally provided on the stator mold. And step motor. 6. The step motor according to claim 3, wherein the lower case or the upper case is provided with a bearing portion that rotatably supports at least one of the rotation transmission gear wheel trains. 7. The step motor according to claim 1, wherein the stator mold or the stator and the yoke are provided with engaging portions that engage with each other and position the yoke.