JP2003199314A - Stepping motor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To attain smooth operation, increase in mean torque, and improvement in a stopping position accuracy by permitting magnetomotive forces on an outer coil winding side and an inner coil winding side to be substantially equal. <P>SOLUTION: Magnetic poles of an outer pole teeth pair, constituted of pole teeth 39b of an outer pole teeth yoke 39 and pole teeth 41b of a middle pole yoke 41, and an inner pole teeth pair, constituted of pole teeth 42b of a middle pole teeth yoke 42 and the pole teeth 40b of a inner pole teeth yoke 40, are changed by the switching of a current direction of an outer coil winding 33A and an inner coil winding 33B, thus a permanent magnet block 29 is rotated. In the stepping motor, the cross-sectional area of the outer coil winding 33A is set to be larger than that of the inner winding 33B, thus the magnetomotive forces of both of the coil windings 33A, 33B are equalized. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a step motor used as an actuator for rotation in various devices.

[0002]

2. Description of the Related Art Conventionally, as a PM type stepping motor, for example, one described in JP-A-7-39130 has been proposed.

In this step motor, an annular plate-shaped outer pole tooth yoke having a plurality of radially inward pole teeth and a disk-shaped inner pole tooth yoke having a plurality of radially outward pole teeth are provided. , An annular plate-shaped intermediate pole tooth yoke having a plurality of outward pole teeth and inward pole teeth is arranged, and the magnetic field is appropriately adjusted by the outer coil winding and the inner coil winding of the electromagnetic coil in the tooth group of these pole tooth yokes. Is generated, the permanent magnet block arranged so as to face the pole tooth yoke is rotated. Specifically, the pole teeth on the opposite sides of the outer pole tooth yoke and the intermediate pole tooth yoke, and the intermediate pole tooth yoke and the inner pole tooth yoke form the outer pole tooth pair and the inner pole tooth pair, respectively. The magnetic poles generated in the tooth pair are appropriately changed by controlling the energization of the outer coil winding and the inner coil winding, thereby changing the magnetic attraction repulsive force acting on the permanent magnet block along the circumferential direction.

Different magnetic poles are magnetized so as to alternate along the circumferential direction on the surface of the permanent magnet block on the side facing the pole teeth of the pole tooth yoke. Further, the outer coil winding and the inner coil winding of the electromagnetic coil have different outer diameters at the winding portions, but wires of the same diameter are wound by the same number of turns.

[0005]

However, in the case of the above-mentioned conventional step motor, the outer coil winding of the electromagnetic coil is longer in the circumferential direction than the inner coil winding.
The electrical resistance when energized is inevitably higher than that of the inner coil winding, and there is a difference in the energizing current between the outer coil winding and the inner coil winding when the same voltage is applied. There is a difference in magnetomotive force.

For this reason, in the conventional step motor, when the permanent magnet block is rotated by changing the energization direction of the outer coil winding, and when the permanent magnet block is rotated by changing the energization direction of the inner coil winding. Therefore, the torque acting on the permanent magnet block changes, the motor operation becomes unstable, and the average torque during the operation cannot be efficiently increased. In addition, in this step motor, the magnetic force acting on the permanent magnet block is different between the energization switching of the outer coil winding and the energization switching of the inner coil winding. There is also a problem that it becomes uniform and the accuracy of the stop position of the permanent magnet block decreases.

Therefore, in the present invention, the magnetomotive forces on the outer coil winding side and the inner coil winding side can be made substantially the same,
An object of the present invention is to provide a step motor that can easily achieve smooth operation, increase in average torque, and improvement in stop position accuracy.

[0008]

As a means for solving the above problems, the present invention is directed to an annular outer pole tooth yoke having a plurality of radially inward pole teeth and a plurality of radially outward pole teeth. An inner pole tooth yoke having pole teeth and arranged on the inner peripheral side of the outer pole tooth yoke, and an adjacent pole of the outer pole tooth yoke arranged between the outer pole tooth yoke and the inner pole tooth yoke. An annular intermediate pole tooth yoke having radially outward pole teeth positioned between the teeth and radially inward pole teeth positioned between the adjacent pole teeth of the inner pole tooth yoke, and an outer pole tooth Outer coil windings that produce different magnetic poles in the outer pole teeth pair formed by the pole teeth of the yoke and the pole teeth of the yoke that are radially outward of the yoke, and the pole teeth that are radially inward of the intermediate pole tooth yoke. Inner pole teeth An inner coil that produces a different magnetic pole in the pair of inner pole teeth composed of the pole teeth of the yoke. And a different magnetic pole are magnetized so that they are alternately arranged along the circumferential direction, and the magnetic pole surface is rotatably provided so as to face the pole teeth of each pole tooth yoke. And a step motor for rotating the permanent magnet block relative to the pole tooth yoke by changing the energization direction with respect to the outer coil winding and the inner coil winding in a predetermined pattern. The cross-sectional area of was larger than that of the inner coil winding. In the case of the present invention, since the cross-sectional area is made larger than that of the inner coil winding by the length of the outer coil winding in the circumferential direction, the energization currents of the outer coil winding and the inner coil winding should be substantially the same. You can

At this time, it is desirable to set the cross-sectional areas of the outer coil winding and the inner coil winding so that the magnetomotive forces of the two are the same.

Further, in the case where the outer coil winding and the inner coil winding are arranged inside the coil yoke for guiding the generated magnetic flux to the corresponding pole tooth yoke, in the winding state of the inner coil winding, the total axial width Is smaller than the total axial width of the outer coil winding in the wound state, and the arrangement of both coil windings in the coil yoke is such that the axial width of the magnetic flux passage on the axial side of the inner coil winding is the outer coil. It is desirable that the width is larger than the axial width of the magnetic flux passage portion on the axial side of the winding. When the outer coil winding and the inner coil winding are arranged on the coil yoke, the outer coil winding is located radially outside the inner coil winding, so the magnetic flux passage portion in the peripheral area of the outer coil winding is inside. Since the circumferential length of the coil winding is longer than that of the magnetic flux passage portion in the circumferential region, a large cross-sectional area can be easily ensured. On the contrary, it is difficult to secure a cross-sectional area because the magnetic flux passage portion in the peripheral region of the inner coil winding is short in the circumferential direction, but a large axial width is secured at least in the axial side portion of the inner coil winding. Therefore, a large cross-sectional area can be secured. Therefore, the magnetic resistance in the coil yoke can be made substantially the same in the peripheral region of the outer coil winding and the peripheral region of the inner coil winding.

Further, according to the present invention, a driven rotating body which is rotationally driven by a crankshaft of an internal combustion engine and a camshaft or a separate member connected to the shaft, and a driven rotating body to which power is transmitted from the driving rotating body. A body, a radial guide provided on either one of the drive rotary body and the driven rotary body, and a side provided so as to be rotatable relative to the drive rotary body and the driven rotary body and facing the radial guide. Of the intermediate rotating body having a spiral guide on its surface, a movable guide portion displaceably guided and engaged with the radial guide and the spiral guide, and rotation of the other one of the drive rotating body and the driven rotating body. In a valve timing control device for an internal combustion engine, comprising a link that swingably connects the movable guide portion and a portion that is separated from the center, in the intermediate rotor, a drive rotor and It is suitable when used in the operation force imparting means for imparting a relative rotational operation force on the kinematic rotor. That is, in the step motor of the present invention, the magnetomotive forces on the outer coil winding side and the inner coil winding side are substantially the same, which makes it possible to stabilize the operation and increase the torque and also to improve the stop position accuracy. Since it surely increases, it becomes possible to accurately and surely change the rotational phases of the driving rotary body and the driven rotary body.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Next, an embodiment of the present invention will be described with reference to the drawings.

In this embodiment, the step motor 4 according to the present invention is applied to an actuator (operating force applying means) portion of a valve timing control device for an internal combustion engine. As shown in FIG. 1, the valve timing control device includes a cam shaft 1 rotatably supported by a cylinder head (not shown) of an internal combustion engine, and a relative rotation of a cam shaft 1 at a front end of the cam shaft 1 as necessary. A drive plate 3 (a drive rotating body in the present invention) having a timing sprocket 2 on the outer periphery, which is assembled so that it can be connected to a crankshaft (not shown) via a chain (not shown), and the drive plate 3 And an assembly angle operation mechanism 5 arranged on the front side of the camshaft 1 (on the left side in FIG. 1) for rotating the assembly angle of the both 3, 1, and this assembly angle operation mechanism 5.
Of the stepping motor 4 which is arranged further forward of the drive mechanism 5 for driving and operating the mechanism 5, and the assembly angle operating mechanism 5 and the stepping motor 5 which are mounted across the cylinder head (not shown) of the internal combustion engine and the front surface of the rocker cover. V covering the front of 4 and surrounding area
TC cover 12 (non-rotating member in the present invention).

The drive plate 3 is formed in a disk shape having a stepped support hole 6 in the center, and the support hole 6 portion is
It is rotatably supported by a flange ring 7 that is integrally connected to the front end of the camshaft 1. The front surface of the drive plate 3 (the surface on the side opposite to the camshaft 1) is shown in FIG.
As shown in FIG. 3, three radial guides 8 composed of a pair of parallel guide walls 8a and 8b are mounted at equal intervals in the circumferential direction and along substantially the radial direction of the plate 3. A substantially rectangular movable guide member 17 is slidably assembled between the guide walls 8a and 8b of the direction guide 8.

On the front side of the flange ring 7, there is arranged a lever shaft 10 (a driven rotary member in the present invention) having three levers 9 radially protruding, and the lever shaft 10 together with the flange ring 7 is bolted. It is connected to the camshaft 1 by 13. One end of a link 14 is pivotally connected to each lever 9 of the lever shaft 10 by a pin 15, and each movable guide member 17 assembled to the radial guide 8 is pinned to the other end of each link 14. It is pivotally connected by 11.

Since each movable guide member 17 is connected to the corresponding lever 9 of the lever shaft 10 via the link 14 in the state of being guided by the radial guide 8 as described above, the movable guide member 17 is Radial guide 8 receiving external force
When displaced along the direction, the drive plate 3 and the lever shaft 10 are relatively rotated by the action of the link 14 by a direction and an angle corresponding to the displacement of the movable guide member 17.

A holding hole 18 (see FIG. 1) is provided at a predetermined position on the front surface side of each movable guide member 17, and a retainer 20 for holding a ball 19 is slidably accommodated in the holding hole 18. In addition, a coil spring 21 for biasing the retainer 20 to the front side is housed. Retainer 2
In No. 0, a hemispherical recess is provided in the center of the front surface, and the ball 19 is rotatably accommodated in this recess.

A substantially disk-shaped intermediate rotating body 2 is provided in front of the protruding position of the lever 9 of the lever shaft 10 via a ball bearing 22.
3 are supported. A spiral groove 24 (spiral guide) having a semicircular cross section is formed on the rear surface of the intermediate rotor 23, and the sphere 1 of each movable guide member 17 is formed in the spiral groove 24.
9 is rotatably guided and engaged. The spiral of the spiral groove 24 is gradually reduced along the rotation direction R of the drive plate 3 as shown in FIGS. 2 and 9 and 10 (in FIG. 2, only the center line of the spiral groove 24 is shown). Is formed. Therefore, the ball 19 of the movable guide member 17
When the intermediate rotor 23 relatively rotates in the delay direction with respect to the drive plate 3 in a state in which is engaged with the spiral groove 24, the movable guide member 17 moves inward in the radial direction along the spiral shape of the spiral groove 24, and Further, when the intermediate rotating body 23 relatively rotates in the forward direction, it moves outward in the radial direction.

In the case of this embodiment, the assembly angle operating mechanism 5
Is the radial guide 8, the movable guide member 17, the link 14, the lever 9, and the intermediate rotating body 2 of the drive plate 3 described above.
It is constituted by three spiral grooves 24 and the like. In this assembly angle operation mechanism 5, when a relative rotational operation force with respect to the cam shaft 1 is input to the intermediate rotor 23 from the step motor 4 which is an operation force imparting means, the movable guide member is moved through the spiral groove 24. 17 is displaced in the radial direction, and further the link 14
Amplifying the turning power to a set magnification via the lever 9 and
A relative turning force is applied to the drive plate 3 and the cam shaft 1.

On the other hand, the step motor 4 has an annular plate-shaped permanent magnet block 29 joined to the outer peripheral edge of the intermediate rotor 23 on the front side (opposite side of the drive plate 3).
And a yoke block 30 of the same annular plate shape that is integrally connected to the lever shaft 10 and an electromagnetic coil block 32 that is locked in the VTC cover 12, and the outside of the electromagnetic coil block 32. Coil winding 33
A and the inner coil winding 33B are connected to a drive circuit (not shown) including an excitation circuit and a pulse distribution circuit, and the drive circuit is controlled by a controller (not shown). The controller receives various input signals such as crank angle, cam angle, engine speed, engine load,
A control signal according to the operating state of the engine is output to the drive circuit as needed.

As shown in FIG. 3, the permanent magnet block 29 has magnetic poles (N) extending in a radial direction on a plane orthogonal to the axial direction.
A plurality of magnetic poles (S poles) are magnetized along the circumferential direction so that different magnetic poles alternate. In FIG. 3, the magnetic pole surface of the N pole is indicated by 36n, and the magnetic pole surface of the S pole is indicated by 36s.

As shown in FIGS. 4 to 6, the yoke block 30 has an annular outer pole tooth yoke 39 and a disc-shaped inner pole tooth yoke coaxially arranged on the inner peripheral side of the pole tooth yoke 39. 40 and a pair of intermediate pole tooth yokes 41 and 42 arranged between the outer pole tooth yoke 39 and the inner pole tooth yoke 40, and these pole tooth yokes 39 to 42 are made of a metal material having high magnetic permeability. The pole teeth yokes 39 to 42 that are formed adjacent to each other are coupled by the resin material 43 that is an insulator, and the inner pole tooth yoke 40 is integrally coupled to the lever shaft 10.

Each pole tooth yoke 39-42 has an annular base 39.
a to 42a and a plurality of pole teeth 39b to 42 extending in the radial direction
b, and the pole teeth 39b and 41b of the outer pole tooth yoke 39 and the middle pole tooth yoke 41, and the pole teeth 39b and 41b of the middle pole tooth yoke 42 and the inner pole tooth yoke 40, and 40b and 42b, respectively, are opposite pole tooth yokes. And extends so that the tips of the pole teeth are positioned between the adjacent pole teeth of the mating pole tooth yoke. In addition, hereinafter, the pole teeth 39b and 41b will be referred to as "outer pole tooth pair",
The pole teeth 40b and 42b are referred to as "inner pole tooth pair". And the pole teeth 39b-4 of each pole tooth yoke 39-42
2b are arranged at equal intervals in the circumferential direction, and the pole teeth 39b to 42b of all the pole tooth yokes 39 to 42 are arranged with a quarter pitch angle shift.

On the other hand, as shown in FIG. 1, the electromagnetic coil block 32 includes a thick disk-shaped coil yoke 34 forming a magnetic path toward the yoke block 30, and an outer coil winding arranged in the coil yoke 34. The wire 33A and the inner coil winding 33B are provided. The outer coil winding 33A and the inner coil winding 33B are wound with the same number of turns, but as shown in the enlarged view of the figure, the cross-sectional area per winding is different, and the outer coil winding 33A side The cross-sectional area is larger than the cross-sectional area on the inner coil winding 33B side.
Both of them are set so that the total axial widths c ₁ and c ₂ in the wound state are larger on the outer coil winding 33A side,
Further, the wall thickness d ₂ of the coil yoke 34 on the axial side portion (the left side portion in FIG. 1) of the inner coil winding 33B is greater than the wall thickness d ₁ of the coil yoke 34 on the axial side portion of the outer coil winding 33A. Is also getting bigger.

The space on the axial side of each coil winding 33A, 33B in the coil yoke 34 is the Koly winding 3
Since the portions 3A and 33B form the magnetic passage portion, the axial side portion of the inner coil winding 33B has an increased cross-sectional area of the magnetic passage portion by an increase in the wall thickness. However, since the inner coil winding 33B originally has a shorter circumferential length than the outer coil winding 33A, the increase in the cross-sectional area due to the increase in the thickness increases the total cross-sectional area of the side portion of the inner coil winding 33B and the outer coil winding 33A. Is almost equal to the total cross-sectional area of the side part. Accordingly, the magnetic resistance in the peripheral area of the inner coil winding 33B and the magnetic path in the peripheral area of the outer coil winding 33A in the coil yoke 34 are substantially equal to each other.

The magnetic entry / exit portion of the coil yoke 34 faces the corresponding base tooth portions 39a-42a of the pole tooth yokes 39-42 of the yoke block 30 via an air gap. Therefore, when the coil windings 33A and 33B are excited to generate a magnetic field in a predetermined direction, the corresponding pole tooth yokes 39 to 39 of the yoke block 30 through the air gap.
Magnetic induction occurs in 42, and as a result, magnetic poles corresponding to the direction of the magnetic field appear in the pole teeth 39b to 42b of the pole tooth yokes 39 to 42, respectively.

The magnetic fields generated by the coil windings 33A and 33B are
The magnetic poles of the pole teeth 39b to 42b facing the magnetic pole surfaces 36n and 36s of the permanent magnet block 29 are switched to one-fourth along the circumferential direction by sequentially switching in a predetermined pattern with respect to the pulse input of the drive circuit. It is designed to move pitch by pitch. Therefore, at this time, the intermediate rotating body 23 follows the movement of the magnetic poles along the circumferential direction on the yoke block 30 and rotates relatively to the lever shaft 10.

A ball bearing 50 is arranged on the inner peripheral surface of the electromagnetic coil block 32, and the block 32 is rotatably engaged with the lever shaft 10 via the ball bearing 50.

Since this valve timing control device has the above-described structure, when the internal combustion engine is started or idled, the assembly angle of the drive plate 3 and the lever shaft 10 is set to the latest as shown in FIG. By maintaining the angle side, the rotation phase of the crankshaft and the camshaft 1 (the opening / closing timing of the engine valve) is set to the most retarded side, and the engine rotation can be stabilized and the fuel consumption can be improved.

Then, when the operation of the engine shifts to the normal operation from this state and a command for changing the rotational phase to the most advanced side is issued from the controller (not shown) to the drive circuit of the electromagnetic coil block 32, The electromagnetic coil block 32 switches the generated magnetic field in a predetermined pattern according to the command, and relatively rotates the permanent magnet block 29 together with the intermediate rotor 23 to the delay side. As a result, the movable guide member 17, which is engaged with the spiral groove 24 by the ball 19, is maximally displaced inward in the radial direction along the radial guide 8, as shown in FIG. Through this, the assembling angle of the drive plate 3 and the lever shaft 10 is changed to the most advanced angle side. As a result, the rotation phases of the crankshaft and the camshaft 1 are changed to the most advanced side, and thereby the output of the engine is increased.

When a command is issued from the controller to change the rotation phase to the most retarded side from this state, the electromagnetic coil block 32 switches the generated magnetic field in a reverse pattern to move the intermediate rotor 23 to the forward side. The movable guide member 17 engaged with the spiral groove 24 by relatively rotating the
As shown in FIG. 2, the maximum displacement is made radially outward along the radial guide 8. As a result, the movable guide member 17 relatively rotates the drive plate 3 and the lever shaft 10 via the link 14 and the lever 9, and changes the rotational phase of the crankshaft and the camshaft 1 to the most retarded angle side.

The rotation phases of the crankshaft and the camshaft 1 are not limited to the positions of the most advanced angle side and the most retarded angle side, but can be changed to any position by the control of the controller. As shown in FIG. 9, it is also possible to change to an intermediate position between the most retarded angle position and the most advanced angle position.

This valve timing control device operates as described above, but the step motor 4 used as the operating force applying means of this device has a cross-sectional area per outer coil winding 33A of the electromagnetic coil block 32. By making the inner coil windings 33B larger than those of the inner coil windings 33B so that the electric resistances of the coil windings 33A and 33B when they are energized are substantially the same, the magnetomotive forces of the coil windings 33A and 33B are substantially the same. become.

Since the cross-sectional area per outer coil winding 33A is larger than that of the inner coil winding 33B, the total cross-sectional area of the outer coil winding 33A is smaller than that of the inner coil winding 33B. However, in this embodiment, the total axial width c ₁ of the outer coil winding 33A is made larger than the total axial width c ₂ of the inner coil winding 33B so that the inner coil winding on the coil yoke 34 is larger. Line 33B
The width (thickness d ₂ ) of the magnetic flux passage portion on the axial side of is larger than the width (thickness d ₁ ) of the magnetic flux passage portion on the axial side of the outer coil winding 33A. It is possible to make the magnetic resistances of the magnetic flux passage portions in the respective circumferential regions of the outer coil winding 33A and the inner coil winding 33B substantially the same.

Therefore, in the step motor 4 of this embodiment, the distance from the rotation center of the outer pole tooth pair and the inner pole tooth pair of the yoke block 30 and the permanent magnet block 29.
By appropriately setting the facing area to the permanent magnet block 29 from the pole teeth 39b and 41b on the outer pole tooth pair side, and the permanent magnet block 29 from the pole teeth 40b and 42b on the inner pole tooth pair side to the permanent magnet block 29. It is possible to make the acting torques the same, thereby smoothing the operation and increasing the torque.

Further, in the case of the step motor 4, the magnetic force acting on the permanent magnet block 29 from the pole teeth 40b and 42b on the inner pole pair side and the outer side are set by setting the facing area of each pole tooth pair and the permanent magnet block 29. Polar teeth opposite pole teeth 39
Since the magnetic forces acting on the permanent magnet block 29 from b and 41b become almost the same, the rotation angle of the permanent magnet block 29 for each step can be made constant and the stop position accuracy can be improved.

That is, for example, the magnetic poles N, S of the pole teeth 39b, 41b, 40b, 42b of the outer pole tooth pair and the inner pole tooth pair are in the state shown in FIG. Is stopped at the position shown in the same figure, at this time, an arbitrary magnetic pole surface, for example, the magnetic pole surface of the south pole of the permanent magnet block 29 in the substantially central part in the same figure, has a large area facing the outer pole tooth pair. And an attracting force is received by the different magnetic pole (N pole) of the inner pole tooth pair (see the normal hatch portion in the figure),
Repulsive forces in opposite directions are received by the same magnetic pole (S pole) on the right side of the pair of outer pole teeth facing each other in a small area and the same magnetic pole (S pole) on the left side of the pair of inner pole teeth (see the cross hatch portion in the figure). From this state, the magnetic poles N and S of the outer pole tooth pair are shown in FIG.
If changed as shown in (B), the magnetic pole surface of the S pole of the permanent magnet block 29 has a different magnetic pole (N pole) of the outer pole tooth pair and a different magnetic pole (N pole) of the inner pole tooth pair facing each other in a large area. By the same magnetic pole (S pole) on the left side of the outer pole tooth pair and the same magnetic pole (S pole) on the right side of the inner pole tooth pair that face each other in a small area. It receives repulsive force in opposite directions (see the cross hatch part in the figure). At this time,
Assuming that the magnetic force on the opposite side of the outer pole teeth is larger than the magnetic force on the opposite side of the inner pole teeth, the permanent magnet block 29 has the structure shown in FIG.
Under this situation, the vehicle will stop at a position slightly deviated to the left side in the figure, and conversely, at the position slightly deviated to the right side in the situation of FIG. 11B, in the step motor 4, Since the magnetic forces of the outer pole tooth pair and the inner pole tooth pair are almost the same, the permanent magnet block 29 is at the center position where it does not shift to the left or right in any of the situations of FIGS. 11 (A) and 11 (B). It will be stopped. Therefore, for this reason, the rotation angle for each step of the permanent magnet block 29 is always constant, and high stop position accuracy can be obtained.

Further, in this embodiment, since the step motor 4 according to the present invention is applied to the valve timing control device of the internal combustion engine, the rotation phases of the crankshaft and the camshaft 1 can be changed accurately and surely. In addition, since the rotational torque can be efficiently increased, it is possible to suppress the consumption of electric power, which is valuable for the vehicle.

Further, the step motor 4 of this embodiment is
In the above, since the magnetomotive forces of the coil windings 33A and 33B can be made the same and the magnetic resistances of the coil windings 33A and 33B in the coil yoke 34 can be made the same, the design of the yoke block 30 is changed. There is an advantage that it can be easily applied to different shapes and sizes.

The embodiments of the present invention are not limited to those described above. For example, in the above embodiments, the intermediate pole tooth yoke 41 having the outwardly facing pole teeth 41b and the inwardly facing pole teeth 41b are provided. Although the intermediate pole tooth yoke 42 having 42b is formed as a separate body, the inward pole tooth and the outward pole tooth may be formed in one intermediate pole tooth yoke. Further, the application of the step motor is not limited to the valve timing control device but may be various other devices.

[0041]

As described above, according to the present invention, since the length of the outer coil winding in the circumferential direction is increased, the cross-sectional area of the wire is made larger than that of the inner coil winding. The magnetic force and the magnetomotive force on the inner coil winding side can be made substantially the same. Therefore, according to the present invention, there is a difference in torque between when the permanent magnet block is rotated by changing the energization direction of the outer coil winding and when the permanent magnet block is rotated by changing the energization direction of the inner coil winding. Since the amount is reduced, the motor operation can be smoothed and the average torque can be increased.

Further, in the present invention, since the magnetomotive forces on the outer coil winding side and the inner coil winding side are substantially the same, the magnetic force acting on the permanent magnet block by switching the energization of the outer coil winding and the inner coil By switching the energization of the windings, the magnetic force acting on the permanent magnet block can be made substantially the same, and as a result, the rotation angle for each step can be made substantially constant and the stop position accuracy can be improved.

[Brief description of drawings]

FIG. 1 is a vertical sectional view showing an embodiment of the present invention.

FIG. 2 is a sectional view taken along the line AA of FIG. 1 showing the same embodiment.

FIG. 3 is a front view of a permanent magnet block showing the same embodiment.

FIG. 4 is a half cross-sectional view of the yoke block taken along the line BB of FIG. 5 showing the same embodiment.

FIG. 5 is a front view of the same embodiment, omitting illustration of a filling resin material of a yoke block.

FIG. 6 is a rear view showing the filling resin material of the yoke block showing the same embodiment, but omitting the illustration thereof.

FIG. 7 is a front view of an electromagnet block showing the same embodiment.

FIG. 8 is a rear view of the electromagnet block showing the same embodiment.

FIG. 9 is a sectional view corresponding to FIG. 2, showing an operating state of the same embodiment.

FIG. 10 is a cross-sectional view corresponding to FIG. 2, showing another operating state of the same embodiment.

FIG. 11 is a view schematically showing the positional relationship between the permanent magnet block and each pole tooth pair and the magnetic force, showing the embodiment.

[Explanation of symbols] 1 ... Camshaft 3 ... Drive plate (drive rotor) 8 ... Radial guide 10 ... Lever shaft (driven rotor) 14 ... Link 17 ... Movable guide member 23 ... Intermediate rotating body 24 ... spiral groove (spiral guide) 29 ... Permanent magnet block 32 ... Electromagnetic coil block 33A ... Outer coil winding 33B ... Inner coil winding 34 ... Coil yoke 39 ... Outer pole tooth yoke 40 ... Inner pole tooth yoke 41, 42 ... Intermediate pole tooth yoke 39b to 42b ... pole teeth

Claims (4)

[Claims] 1. An annular outer pole tooth yoke having a plurality of radially inward pole teeth, and a plurality of radially outward pole teeth, which are arranged on an inner peripheral side of the outer pole tooth yoke. An inner pole tooth yoke, and arranged between the outer pole tooth yoke and the inner pole tooth yoke,
An annular intermediate having radially outward pole teeth positioned between adjacent pole teeth of the outer pole tooth yoke and radially inward pole teeth positioned between adjacent pole teeth of the inner pole tooth yoke. A pole tooth yoke, an outer coil winding that causes different magnetic poles in the outer pole tooth pair formed by the pole teeth of the outer pole tooth yoke and the pole teeth of the middle pole tooth yoke facing outward in the radial direction, and the middle pole tooth yoke Inner coil windings that generate different magnetic poles on the inner pole teeth formed by the pole teeth facing inward in the radial direction and the pole teeth of the inner pole tooth yoke, and the different magnetic poles are arranged alternately along the circumferential direction. And a permanent magnet block rotatably provided so that the magnetic pole surface faces the pole teeth of each of the pole tooth yokes, and the energization directions for the outer coil winding and the inner coil winding are predetermined. By changing the pattern, A step motor that rotates relative to a tooth yoke, wherein the cross-sectional area of the outer coil winding is larger than the cross-sectional area of the inner coil winding. 2. The step motor according to claim 1, wherein the cross-sectional areas of the outer coil winding and the inner coil winding are set so that the magnetomotive forces of the two are the same. 3. The step motor according to claim 1, wherein the outer coil winding and the inner coil winding are arranged inside the coil yoke for guiding the generated magnetic flux to the corresponding pole tooth yoke. The total axial width of the inner coil winding is smaller than the total axial width of the outer coil winding, and the arrangement of both coil windings in the coil yoke is set to the magnetic flux passage section on the axial side of the inner coil winding. The axial width of the step motor is larger than the axial width of the magnetic flux passage portion on the axial side of the outer coil winding. 4. A driven rotating body that is rotationally driven by a crankshaft of an internal combustion engine, and a driven rotating body that is composed of a camshaft or a separate member coupled to the shaft, and that is driven by the drive rotating body. A radial guide provided on one of the drive rotating body and the driven rotating body,
An intermediate rotating body that is provided so as to be rotatable relative to the drive rotating body and the driven rotating body and has a spiral guide on a surface facing the radial guide, and is displaceable between the radial guide and the spiral guide. A movable guide portion that is guided and engaged with
A valve timing control device for an internal combustion engine, comprising: a link that oscillates between the movable guide portion and a portion of the other of the drive rotor and the driven rotor that is separated from the center of rotation, The step motor according to any one of claims 1 to 3, wherein the step motor is used as an operation force applying unit that applies a relative rotational operation force to the rotating body with respect to the drive rotating body and the driven rotating body.