JP3134242B2 - Step motor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

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

[0002]

2. Description of the Related Art In recent years, a so-called quartz clock using a quartz oscillator has become widespread. In a clock station installed in an inaccessible place such as a station or on a high wall, time can be quickly and remotely adjusted by remote control. I am able to do it accurately. As a motor applicable to such a remotely operable quartz timepiece, there is known a two-phase excitation step motor capable of rotating forward and reverse by controlling the phase of a signal supplied to an excitation coil.

FIGS. 10 to 13 show a conventional example of such a two-phase excitation type step motor. FIG. 10 is a sectional view of the step motor, FIG. 11 is a perspective view of a rotor magnet and stator assembly, and FIG. FIG. 13 is a diagram showing an excitation pattern. In these figures, reference numeral 20 denotes a watch case composed of an upper case 21 and a lower case 22. The case 20 includes a rotor magnet 1 and upper and lower
Sets of stator assemblies 2 and 3, minute hand shaft 33, hour hand shaft 36,
The gear transmission mechanism 23 and the like are housed.

As shown in FIG. 11, the rotor magnet 1 has three magnetic poles N1, N2, N3, S1, S2 on the outer periphery.
, 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. A gear 26 is provided integrally with the upper part of the rotor magnet 1.
The rotation of the gear 30 through the rotation gear 30a, the gear 31, the gear 31a, and the gear 32;
The power 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 has a gear 35 integrally therewith and is rotatably fitted on the upper portion of the minute hand shaft 33.

The upper stator assembly 2 includes a pair of stators 4 and 5 and an exciting coil 6 for exciting the stators 4 and 5. The pair of stators 4 and 5
The stators 4 and 5 are arranged in the same plane orthogonal to the axis of the rotor magnet 1 and form a magnetic circuit via the rotor magnet 1. The stators 4 and 5 are formed in a U-shape in plan view and symmetrical in shape. Are arranged so as to face each other, and one ends thereof are opposed to each other with the rotor magnet 1 interposed therebetween to form stator magnetic pole portions 7 and 8, respectively, and the other ends 9 and 10 around which the exciting coil 6 is wound. Is inserted into a bobbin 40 made of a non-magnetic material such as synthetic resin. The opposing surfaces of the stator magnetic pole portions 7 and 8 are formed into semicircular concave surfaces over a range of approximately 180 ° so as to oppose the outer periphery of the rotor magnet 1 with an appropriate gap G therebetween.

The lower stator assembly 3 has the same structure as the upper stator 2 described above, and includes a pair of stators 11 and 12 and an exciting coil 13, and the exciting coil 13 is connected to the exciting coil 6. And the stator 2 on the upper side so as to be located on the opposite side of the rotor magnet 1 with a 180 ° phase difference in the circumferential direction of the rotor magnet 1. Ends of the stators 11 and 12 opposed to each other with the rotor magnet 1 interposed therebetween are stator magnetic pole portions 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 coils 6
13, when the stators 4, 5, 11, and 12 are excited in two phases, four excitation patterns, namely, (N, S, N,
S), (N, S, S, N), (S, N, S, N) and (S, N, N, S) are obtained. When these excitation patterns are continuously changed in this order, , Rotor magnet 1
The rotor magnet 1 rotates at a constant speed in a predetermined direction by a magnetic action between the rotor magnet 1 and the stators 4, 5, 11, and 12. The rotation of the rotor magnet 1 is transmitted to the minute hand shaft 33 and the hour hand shaft 36 via the gear transmission mechanism 23 in a reduced speed, and the minute hand shaft 33 rotates once per hour.
6 is rotated 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 corrected. 11 and 12 show the state of the excitation pattern (N, S, N, S), and FIG. 13 shows the state of the excitation pattern (N, S, S, N).

FIG. 14 is a view showing an exhaust gas recirculation system of an automobile engine, and FIG. 15 is a sectional view of a step motor used in the system. The 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 channel 53, and an exhaust gas inlet 53 a of the recirculation channel 53 is 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 channel 53 is adjusted.

The control valve 55 is provided with a valve shaft 5 movably provided in a housing 56 provided integrally on the outer periphery of the exhaust pipe 51.
7 and a plug 5 integrally provided at the tip of the valve shaft 57.
And a compression coil spring 59 for urging the valve shaft 57 in a direction in which the plug 58 closes the exhaust gas inlet 53a. On the peripheral surface of the housing 56, the recirculation flow path 5 is provided.
An outlet 53b communicating with the third port 3 is formed.

The step motor 54 is formed by molding and disposed in a motor housing 61, and is inserted into the stator assembly 62 with an appropriate gap therebetween and is rotatably driven by a bearing 63. The rotor magnet 60 is supported. The stator assembly 62 includes four stators 62a to 62a to
62d. These stators 62a-6
Outer stators 62a and 62d of 2d are integrally provided with folded portions 72 that are bent in the directions of the other stators 62b and 62c, respectively. , 6
2c is magnetically coupled. Each excitation coil 64
The stators 62 a and 62 b, 62 c and 62 d which are wound around the bobbin 74 and constitute each set of stator assemblies are respectively connected to terminals 70. In the manufacture of such a stator assembly 62, each stator assembly is separately formed, overlapped, and 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 formed with the synthetic resin 73, and the stator 62a is fitted thereto, thereby forming one stator assembly. In addition, the exciting coil 64 wound around the bobbin 74, the terminal 70, and the stator 62c are integrally formed of a synthetic resin 73, and the stator 62d is fitted thereto, thereby forming the other stator assembly. The motor housing 61 and the stator assembly 62 are integrally formed by stacking these stator assemblies with an intermediate plate 71 made of aluminum or the like interposed therebetween, and loading and mounting the same in a mold.

The rotor magnet 60 is formed in a cylindrical body, and has a center hole 60a in which a plug 5 of the valve shaft 57 is inserted.
An end opposite to the side 8 is slidably and non-rotatably fitted in the direction of the axis K2. That is, the valve shaft 57 is
The intermediate portion is slidably and prevented from rotating by an oil metal 67 provided on the motor housing 61, and a male screw 68 is formed on the outer periphery of the rotor side end. 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 in a cylindrical body by a synthetic resin or the like,
A female screw 69a with which the male screw 68 is screwed is formed on the inner peripheral surface. Accordingly, 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 the valve shaft 57 moves forward, the plug 58 closes the inlet 53a.

In the conventional stepping motor shown in FIGS. 10 to 13, the exciting coil 6 (1
3), and a plate-like yoke 41 is disposed inside the bobbin 40. The other ends 9, 1 of the stators 4, 5 are provided in the bobbin 40.
0 is inserted and the other ends thereof are magnetically connected by the yoke 41, so that there is a problem that the assembly work of the stator assemblies 2, 3 is complicated. In addition, bobbin 40
Are provided at both ends of the upper and lower stator assemblies 2, 3, respectively.
In this case, there is a problem that the connection of the external wiring cannot be concentrated at one location because the terminal 42 is taken upside down and the position around the rotor magnet 1 is 180 ° out of phase. 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.
In one of the two stators (62b,
62c), the excitation 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. Thereafter, these stator assemblies need to be overlapped. Therefore, there has been a problem that the management of component dimensions and the number of assembly steps are increased.
Further, there is a problem that the assembling work of the stator is troublesome, and the number of parts increases because the bobbin 74 is used similarly to the above-described conventional step motor.

Therefore, in order to solve such a problem,
There has been proposed a step motor in which an exciting coil is wound around the outer periphery of a magnetic pole portion of a stator assembly via a mold resin without using a bobbin (Japanese Patent Laid-Open No. 61-12176, hereinafter referred to as a prior invention). That is, this step motor molds four stators, each of which is a set of two, into a stator assembly, and covers a surface portion of each set of stator assemblies where the exciting coils are wound and closely contacted with a mold resin,
The stator assembly is inserted into a cylindrical yoke that also serves as a frame.

[0015]

In the above-mentioned prior invention, although the manufacture is easy, the bobbin is not required, and the number of parts can be reduced, the outer circumferences of all four stators can be matched. Since it is difficult, when the stator assembly is inserted into the yoke which 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.
1 and 12 are superposed with the magnetic pole part (110) shifted by a half pitch. Therefore, the four stators 4, 5, 11,
Numeral 12 is slightly different in shape, and the upper and lower two stators 4, 1
Since the two are the same, they are pressed with the same mold so that the magnetic pole portions face each other. In other words, one is reversed. Since the intermediate stators 5 and 11 are the same and different from the stators 4 and 5, they are pressed by another identical type, 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 the stators 11 are different or eccentric, when the four stators 4, 5, 11, and 12 are overlapped with the center of the magnetic pole portions coincident, a step occurs on the outer periphery of each stator. Therefore, when the stator assembly is inserted into the yoke, a gap is formed between each stator and the yoke, and as a result, the magnetic efficiency decreases.

Such a step also occurs when four stators are molded. That is, when molded, the mold resin contracts in the axial and radial directions of the stator when cooled. This shrinkage is not constant in each part of the mold resin, but varies depending on the 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 periphery of each stator when contracted in the radial direction. As described above, in the above-described prior invention, the step due to the outer diameter of the stator, the eccentricity, and the like, and the step due to the shrinkage of the mold resin after the molding are serious problems, but it is extremely difficult to eliminate such a step in manufacturing. It was difficult.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned conventional problems. It is an object of the present invention to eliminate the need to control the outer diameter of the stator and to keep the yoke close to the exciting coil. An object of the present invention is to provide a stepping motor that can be driven. Another object of the present invention is to provide a step motor capable of securely attaching a yoke to a stator assembly by one operation.

[0018]

In order to achieve the above-mentioned object, a step motor according to the present invention is formed by molding and integrating four stators, two of which are set as one set and stacked with their axes aligned. a stator mold, an exciting coil wound around the magnetic pole portion outer periphery of each set of stator, and rotatably inserted rotor magnet in the stator, parallel
And has two elongated plate portions curved in a U-shape.
And each plate part is formed separately from the data mold.
With respect to the excitation coil between the stators, the stator motor
Yoke that is detachably fitted from a direction perpendicular to the axis of the
And the tip of the yoke is connected to the exciting coil.
It is characterized by being bent along the outer periphery to cover the outer periphery of the exciting coil . The present invention also relates to a stator mold shaft.
At both ends in the line direction, a metal cylinder and a resin cylinder are
The cylindrical part and the cylindrical body are integrally provided by screw molding.
The rotor magnet is used as a bearing holding portion of a bearing that supports the rotor magnet.
Characterized in that was. Further, in the step motor according to the present invention, the stator mold is connected to the stator assembly and the lower casing.
And the lower case is connected to the stator assembly.
Consists of an upper plate and a lower plate that are held from above and below,
Connect multiple terminals to the upper plate to which the ends of the excitation coil are connected.
A terminal holding portion for holding the battery collectively is provided integrally with the lower plate portion.
A plurality of small holes through which the lower end of the terminal is inserted.

In the present invention, the four stators are molded to form one part by forming a stator mold. The yoke is a stator motor between each set of stators.
Fitting from the side of the field . Therefore, there is no problem even if a step occurs on the outer periphery of the stator. For stator mold
The metal cylinder and the molded resin cylinder keep the bearing.
The bearing holding part to hold is formed. The terminal holding portion of the stator mold collectively holds a plurality of terminals to which the ends of the exciting coil are connected at one location. Therefore, the connection work of the external wiring can be easily performed from one direction. Terminal is Roake
Is inserted through the small hole of the case.

[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. FIGS. 6 (a) and 6 (b) are a development view of the yoke and a plan view in a bent state, 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 constituting each set of the stator assemblies 2, 3 are integrally formed with the lower case 22 by molding to form a stator mold 80. For this reason, the stators 4, 5, 11, and 12 constituting each of the stator assemblies 2 and 3 are formed.
As shown in FIG. 4, the surface of the excitation coils 6 and 13 in close contact with each other, that is, the surface facing the outer surface of the pole teeth 110 (described later) constituting the respective magnetic pole portions in the axial direction is covered with the mold resin 111 (see FIG. 4). (A resin coating portion) 111a.

The lower case 22 comprises an upper plate portion 22a and a lower plate portion 22b which are vertically opposed to each other. 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 these plate portions 22a and 22b. Bearing portions 81 and 82 that rotatably support the portion 91b are provided integrally. The bearing 81 of the minute hand shaft 33 is formed of a protrusion having a circular cross section, and the bearing 82 of the rotor magnet 1 is formed as a circular concave portion. Further, 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) are integrally provided on the upper plate portion 22a so as to protrude. The terminal holding portion 84 extends behind the upper plate portion 22a, and collectively holds a plurality of terminals 85 to which the ends of the exciting coils 6, 13 are connected. Each terminal 85
Extends below the lower case 22 through a small hole 87 provided in the lower plate portion 22b, and is electrically connected to a drive circuit of a printed circuit board (not shown). in this way,
When a plurality of terminals 85 are provided in a concentrated manner at one location, connection work of external wiring is easy.

In the rotor magnet 1, 5 to 10 magnetic poles (N1 to N5, S1 to S5) are alternately magnetized at equal intervals in the circumferential direction, similarly to the above-described conventional rotor magnet. It is rotatably inserted into the center hole 90 (FIG. 4) of the stator mold 80 so that the center of the stator mold 80 and the center of the shaft 1A are 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 reduced by a gear 94 provided above the shaft 1A and a gear 95 meshing therewith and transmitted to the minute hand shaft 33. The rotation of the minute hand shaft 33 is performed by the gear 96-the reverse gear (reduction gear).
The power is transmitted to the hour hand shaft 36 via the 97-gear 98-gear 99. The hour hand shaft 36 is rotatably fitted to the minute hand shaft 33, and its upper end projects upward from the hole 100 of the upper case 21 together with the minute hand shaft 33. Sun gear 97
The lower case 22 is rotatably supported by a shaft 101 suspended from the inner surface of the upper case 21, and the lower surface is supported by the upper surface of the upper plate portion 22 a of the lower case 22. 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. are covered. In addition,
A clock holding spring 104 is attached to the outer periphery of the lower end of the hour hand shaft 36 so as to urge the minute hand shaft 33 and the hour hand shaft 36 downward by being pressed against the inner surface of the upper case 21 to prevent rattling in the thrust direction. Have been.

In FIG. 5, the pair of stators 4 and 5, 11 and 12 constituting the upper stator assembly 2 and the lower stator assembly 3, respectively, are formed in substantially the same disk shape as described above. On its inner peripheral side, five pole teeth 110 forming a stator magnetic pole portion are equally arranged in the circumferential direction, and are bent at substantially right angles downward and upward so as to face each other. The pole teeth 110 have a triangular shape, and the inner surface thereof forms the inner wall surface of the center hole 90 (FIG. 4) of the stator mold 80. The exciting coils 6 and 13 are directly wound via the resin covering portion 111a formed by molding the mold 80. Therefore, the resin coating portion 111a functions as a bobbin. These exciting coils 6, 13 are wound after the stators 4, 5, 11, 12 and the lower case 22 are molded.

A pair of positioning recesses 112 are provided on the outer peripheral edge of each of the stators 4, 5, 11, and 12 with a phase shift of 180 °, respectively.
When the four stators are overlapped with each other, the pole teeth 110 of each set of stator assemblies 2 and 3 are located between the pole teeth of the counterpart 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 the holes 11 and 12, and the insertion strength of the stators 5 and 11 and the stators 4 and 12 and the lower case 22 is increased by filling the holes 113 with the mold resin 111. I have. A yoke 41 that forms a magnetic circuit with the stators 4, 5, 11, and 12 is detachably fitted from the side of the stator mold 80, and covers the excitation coils 6, 13. In addition, such stators 4, 5, 11, 12
Are stacked with the pole teeth 110 shifted by a half pitch, so that the stators 4 and 12 are of the same type,
1 are each press-molded in another identical mold.

As shown in FIG. 6 (a), the yoke 41 has two elongated plate portions 41a and 41b formed in parallel by punching a metal plate or the like, and a connection for connecting the two end portions of these plate portions to each other. Parts 41c and 41d,
(B) As shown in the figure, the plates 41a and 41b are bent into a substantially U-shape, and the respective plates 41a and 41b are fitted between the stators 4 and 5, 11 and 12, respectively. The arc portion of the yoke 41 has substantially the same size as the outer shape of the exciting coils 6 and 13. Also, both ends of each of the connecting portions 41c and 41d protrude appropriately above and below the yoke 41 so that the yokes 4
An engaging portion 115 is formed for positioning 1 with respect to the stators 4, 5, 11, and 12.

As described above, such a yoke 41 has a structure in which the respective plate portions 41 a and 41 b form the upper stator assembly 2 and the lower stator assembly 3 from the side of the lower case 22. The excitation coils 6 and 13 are respectively fitted between them to cover the excitation coils 6 and 13. 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 yoke 41 is positioned and locked to the stator assemblies 2 and 3 by the engagement of the connecting portions 41c and 41d with the positioning recesses 112 of the stators 5 and 11, respectively. The linearly formed distal ends of the plate portions 41a and 41b are inwardly provided around the connecting portions 41c and 41d as fulcrums in order to ensure magnetic coupling with the stators 4, 5, 11, and 12. Bendable. In this case, each plate portion 41a, 4
1b is fitted between the stators 4 and 5, 11 and 12 of each set, so that it can be in close contact with the exciting coils 6 and 13. In FIG. 3, reference numeral 116 denotes 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, 12 and the lower case 22 constituting the pair of stator assemblies 2, 3 are integrally formed by molding, and the resin covering portion 111a is formed. Since the exciting coils 6 and 13 are directly wound around the outer periphery, the conventionally required bobbin is unnecessary, and the number of parts can be reduced. In particular, in the present invention, after winding the exciting coils 6 and 13 around the outer circumference of the magnetic pole portions of the stators 4 and 5 and 11 and 12 of each of the stator assemblies 2 and 3,
Since 1a and 41b are fitted between the stators of the respective stator assemblies 2 and 3 from the side of the stator mold 80, the stators 4, 5, 11 and 12 are caused by manufacturing errors, eccentricity, shrinkage of the mold resin, and the like. There is no problem even if a step occurs on the outer periphery of the stator, and the management of the outer diameter of the stator is easier than in the above-described prior invention. Further, the engaging portion 115 and the engaging portion 1
15 and the recess 112 for positioning, the yoke 4
Since it is sufficient to lock the yoke 41 to 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. The yoke 41 is connected to the exciting coils 6 and 13.
It is possible to be close. Further, the minute hand shaft 33 and the bearings 81 and 82 of the rotor magnet 1 are provided in the lower case 22.
In addition, since the terminal holding portion 84 of the terminal 85 is provided integrally, the number of parts can be further reduced. Further, since the plurality of terminals 85 to which the excitation coils 6 and 13 are connected are concentrated on the terminal holding portion 84, the connection work of the external wiring is also 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. In this case, the stators 4, 5, 11, 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 cylinder 134, which are stacked and arranged with their axes aligned, are molded and integrated with a synthetic resin to form the stator mold 130. The outer circumference of the magnetic pole portion and the surface facing in the axial direction of the stators 62a and 62b and 62c and 62d are covered with the covering portion 111a of the mold resin 111.
4, 64 are wound respectively. A yoke 132 is provided between each pair of stators 62a and 62b, and 62c and 62d.
Are fixed, and are detachably fixed by engagement between an engaging portion (not shown) and a concave portion provided on the stator 132 side. Such a yoke 132 is formed in the same U-shape as the yoke 41 (see FIG. 6) shown in the above-described embodiment, and the tip is bent along the outer circumference of the exciting coil 64.

The cylindrical portion 111b and the cylindrical body 134 provided at the lower end of the mold resin 111 form bearing holding portions, respectively, and respectively hold the bearings 63 that support the rotor magnet 60. An intermediate portion of the valve shaft 57 movably disposed in the rotor magnet 60 is rotatably supported by an oil metal 67 provided in the housing 56. Further, the valve shaft 57 is urged toward the rotor 60 by the compression coil spring 133. This is to eliminate backlash in the engagement between the valve shaft 57 and the screw body 69. A pin 135 is driven into an 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 a pin 136. In the figure supporting the rotor 60, the upper bearing 63 and the housing 5
6, a conical coil spring 137 for holding the bearing 63 and the rotor 60 is elastically mounted. Terminal 7
0 is connected to a printed circuit board 139, and a lead wire 140 is connected to the printed circuit board 139 via a connector 141. Other configurations are substantially the same as those of the conventional step motor shown in FIG. 15, and therefore, the same components and the like are denoted by the same reference numerals, and 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, so that the same effect as in 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 disposed in a motor housing 151, and a rotation transmission gear train 155 disposed 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 rotating shaft 156, and forms a slight gap between the outer peripheral surface and the stator mold 153, that is, a magnetic gap. The stator mold 153 includes four stators 161a to 161d, each of which includes two stators 161a to 161d, which are stacked and arranged with their axes aligned.
1a to 161d are molded and integrally formed with a molding resin 111. In the center of the upper surface of the mold resin 111, a through hole 163 through which the rotating shaft 156 passes is formed, and a bearing 164 is provided. Also, the outer peripheral surfaces of the magnetic pole portions and the axially opposed surfaces of the stators 161a and 161b and 161c and 161d of each pair are covered with the resin coating portion 111a, and the exciting coils 165 and 165 wound around the magnetic pole portions are provided.
A yoke 166 is attached to the outside of the. The yoke 166 is the same as the yoke 4 shown in the above-described embodiment.
1 (see FIG. 6) and 132 (see FIG. 8) are formed in a U-shape, and the stators 161a, 161b, and 161 of each set are formed.
c and 161d, respectively, and are detachably fixed by engagement of an engaging portion (not shown) and a concave portion. In addition,
The excitation coil 165 is connected to the terminal 167.

The rotating shaft 156 is connected to the motor housing 1.
Bearing 168 and stator mold 1 provided on the inner bottom surface of
It is rotatably supported by the bearing 164 provided on the 53 mold resin 111. One end of the rotating shaft 156 penetrates through the through hole 163 of the mold resin 111 and protrudes into the motor housing 154, and one gear 170 constituting the rotation transmission gear train 155 is fixed to the protruding end. Have been. The rotation transmission gear train 155 is
The gear 170 and the rotation of the gear 170 are output to the output shaft 17.
2 are provided with gears 173 to 177.

With such a structure, the same effect as in 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 molding and integrating four stators which are stacked and arranged with their axes aligned. An exciting coil is wound around the outer circumference of the magnetic pole portion of the set of stators, a rotor magnet is rotatably inserted into the stator, and a U-shaped yoke is mounted between the stators of each set from the side of the stator mold. Since the excitation coil is removably fitted to cover the exciting coil, it is easy to attach the yoke, and there is no problem even if a step occurs on the outer periphery of the stator due to a manufacturing error, eccentricity, shrinkage of the molding resin, and the like. Thus, the outer diameter of the stator can be easily controlled, and the yoke can be closely contacted with the exciting coil. Further, since the yoke is fitted between the stators of each set, the area where the yoke fracture surface comes into contact with the stator increases, and variation in magnetic efficiency can be reduced.

The present invention also relates to a method for manufacturing a stator mold using metal.
Of the cylinder and the stator mold mode
A cylindrical part is provided in the mold resin, and this cylindrical part and the cylindrical body are
As the bearing holding part of the bearing that supports the magnet,
The number of parts and the number of assembling steps can be reduced, and the assembling workability can be improved. The present invention also provides a stator molding
Multiple terminals to which the ends of the excitation coil are connected
The terminal holding part that holds the
Since a plurality of small holes into which the terminals are inserted are formed , there is no need to provide any separate member, and the number of parts and the number of assembling steps can be further reduced. In addition, a plurality of terminals can be arranged in a concentrated manner in the terminal holding portion, thereby facilitating wiring connection work.

[0038]

[Brief description of the 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.

FIGS. 6A and 6B are a developed view and a plan view of the yoke in a bent state, respectively.

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

FIG. 10 is a 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 of an automobile engine.

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

[Explanation of symbols]

1 ... rotor magnet, 2, 3 ... stator assembly, 4,
Reference numeral 5: stator, 6: excitation coil, 7, 8: stator magnetic pole portion, 11, 12: stator, 13: excitation coil, 14,
15: stator pole portion, 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 teeth (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.

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-7-231641 (JP, A) JP-A-1-248952 (JP, A) JP-A-5-176518 (JP, A) 34673 (JP, U) (58) Fields investigated (Int. Cl. ⁷ , DB name) H02K 37/00-37/24

Claims (3)

(57) [Claims] 1. A stator mold formed by molding and integrating four stators, two of which constitute one set and stacked 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 into the stator and parallel and curved in a U-shape.
Separate from the stator mold with two elongated plates
And each plate portion is provided between the stators of each set.
Perpendicular to the axis of the stator mold with respect to the magnetic coil
And a yoke that is removably fitted from a different direction.
Bend the end of the yoke along the outer circumference of the exciting coil
A step motor covering an outer circumference of an exciting coil . 2. The stepping motor according to claim 1 , wherein metal cylinders are provided at both ends of the stator mold in the axial direction.
The body and the cylindrical part made of resin are integrally formed by molding.
The cylindrical part and the cylindrical body are
A step motor comprising a bearing holding portion for a bearing to be supported. 3. The step motor according to claim 1, wherein the stator mold and the stator assembly
And the lower case is connected to the stator assembly.
The upper and lower plates hold the
Multiple terminals to which the ends of the excitation coil are connected to the upper plate
Terminal holding portion for holding the
A stepped motor formed with a plurality of small holes through which the lower end of the terminal is inserted.