JP5127865B2 - DC motor and valve opening / closing device - Google Patents

Description

  The present invention relates to a valve opening / closing device used for an exhaust gas recirculation device or the like, which has a return spring for closing the valve, and changes the rotation direction to change the opening / closing operation of a driven body (valve) or a predetermined value. The present invention relates to a direct current motor serving as a drive source for maintaining drive in position. The present invention also relates to a valve opening / closing device equipped with the DC motor.

  Conventionally, a direct current motor has been used as a drive source for a device having a linear motion mechanism of an output shaft, such as a valve opening / closing device or an actuator.

  For example, an EGR valve for vehicle use (EGR is an abbreviation for Exhaust Gas Recirculation, which is translated as “exhaust gas recirculation device” in Japanese. In the exhaust gas mixing device), a direct current motor serving as a drive means for a control valve that opens and closes the exhaust gas passage, a rotor rotatably supported in the motor case via a bearing, and a rotor shaft center portion are passed through. A screw shaft having a screw hole and having a control valve at the tip is screwed into the screw hole, and the screw shaft moves in the axial direction by rotation of the rotor, and the valve is opened. When the valve is closed, the rotor rotates in the opposite direction to that when the valve is opened. Further, an EGR valve provided with a return spring has been proposed so that the valve can be kept closed when power cannot be supplied to the DC motor (see, for example, Patent Document 1).

  In order to make the EGR valve configured as described above perform a desired operation, an energization control device is provided. Especially in energization control when the valve is closed, a stopper (control valve and screw shaft) provided in the rotor is provided. The braking control is applied from the middle of the valve closing so that the positioning mechanism) is not damaged by the collision of the shaft.

  Further, the DC motor as a drive source has a configuration in which the armature is disposed on the stator side and the field magnet is disposed on the rotor side. Although not shown, in this case, in order to switch the energization of the armature, a power supply brush and a power distribution brush are provided on the stator side, and project toward the commutator disposed on the rotor.

  Further, valve opening / closing devices and valve actuators having other return springs using a direct current motor in which the armature is disposed on the rotor side and the field magnet is disposed on the stator side have been proposed (for example, Patent Document 2).

WO2003 / 026123 Japanese Patent No. 3274763

  In recent years, motors mounted on all products have been required to have high performance and low cost. In particular, there are many examples in which DC motors are used in automobiles with a large number of produced parts and a large number of components. . In particular, DC motors, which are the driving sources of valve opening and closing devices such as exhaust gas recirculation devices, which are one of the components of automobiles, have high performance requirements and high open / close responsiveness in addition to cost reduction. In order to improve, there is a demand for higher output and lower inertia of the DC motor.

  Further, the load torque of a device having an opening / closing mechanism often varies depending on the rotation direction. In the example of Patent Document 1, a force is applied in a direction in which the return spring pushes the valve back in the valve closing direction, so that the load torque in the valve opening direction is larger than that in the valve closing direction. That is, among the high output, a high torque in the valve opening direction is required.

  Examples of means for increasing the output of the DC motor include increasing the magnetic force of the field magnet and increasing the size of the armature core, that is, expanding the outer diameter and extending the core shaft length.

  However, increasing the magnetic force of the field magnet tends to increase the cost of the magnet and increase the cogging torque, and increasing the armature core tends to increase the inertia.

  Further, as a means for reducing inertia, there is a reduction in the size and weight of the rotor. For example, in the said patent document 1, the rotor is reduced in weight by making a rotor into a field magnet. In another example, the required torque is secured by using a gear on the output shaft, and the armature core of the rotor is reduced in diameter (the motor itself has high rotation and low torque specifications).

  However, in the example in which the rotor is a field magnet, the armature on the stator side is energized via the commutator installed on the rotor side, so the mechanism for rectification becomes complicated and expensive. In the example in which the output shaft is provided with a gear, there has been a tendency to increase the cost and the size of the apparatus.

  Further, as a means for realizing high torque in one direction, an example in which the energization phase angle formed by the positional relationship between the brush and the commutator is set to the advance angle can be given.

  However, in the above example, the energization phase angle becomes a lagging phase in the reverse direction, so that torque pulsation tends to increase remarkably.

  The present invention has been made in order to solve the above-described problems, and is an armature rotating type DC motor that realizes high output and low inertia without increasing cost and cogging torque pulsation. And a valve opening / closing device equipped with the DC motor.

A DC motor according to the present invention is an inner rotor type DC motor in which an armature is a rotor and a field is a stator,
The field is
A field core formed in a predetermined shape by a magnetic material;
A plurality of field magnets provided at predetermined locations of the field core;
A field coil wound with a predetermined number of turns so as to surround each of the field magnets at a substantially right angle with respect to the axial direction,
Adjacent field coils are configured to have different current directions.

  The direct current motor according to the present invention includes a field coil wound by a predetermined number of turns so as to surround each of the field magnets at a substantially right angle with respect to the axial direction, and a current flowing through the field coil connected to the power source is It can flow in the direction of increasing the magnetic flux of the field in the rotational direction, and the rotational torque can be increased, and a high-output DC motor can be obtained with a simple configuration.

FIG. 3 shows the first embodiment, and is a longitudinal sectional view of a valve opening / closing device 100 on which a DC motor 200 is mounted. FIG. 5 shows the first embodiment, and is a cross-sectional view of DC motor 200 (cross-sectional view taken along line BB in FIG. 3). FIG. 3 shows the first embodiment, and is a longitudinal sectional view of the DC motor 200 (AA sectional view of FIG. 2). FIG. 5 shows the first embodiment, and is a cross-sectional view of the armature 20 (DD cross-sectional view of FIG. 5). FIG. 5 shows the first embodiment, and is a longitudinal sectional view of the armature 20 (CC sectional view of FIG. 4). FIG. 5 shows the first embodiment, and is a cross-sectional view of the armature core 21. FIG. 5 shows the first embodiment and is an enlarged plan view in the vicinity of the armature slot 23; FIG. 5 shows the first embodiment, and is a cross-sectional view of the field 10 (FF sectional view of FIG. 9). FIG. 5 shows the first embodiment, and is a vertical cross-sectional view of the field 10 (cross-sectional view taken along line EE in FIG. 8). FIG. 5 shows the first embodiment and is a cross-sectional view of the field iron core 11. FIG. 5 is an enlarged cross-sectional view of the field magnet 12 showing the first embodiment. FIG. 5 shows the first embodiment and shows the winding direction of the field coil 13. FIG. 5 shows the first embodiment, and shows a winding method (wave winding) of the field coil 13. FIG. 5 shows the first embodiment and is a connection diagram of the DC motor 200; FIG. 5 shows the first embodiment and shows the direction of magnetic flux generated by the field magnet 12 and the direction of magnetic flux generated by the field coil 13 when the DC motor 200 rotates forward. FIG. 5 shows the first embodiment, and shows the direction of magnetic flux generated by the field magnet 12 and the direction of magnetic flux generated by the field coil 13 when the DC motor 200 is rotated in reverse. FIG. 5 shows the first embodiment and shows the relationship between the torque and the rotational speed of the DC motor 200. FIG. FIG. 5 is a diagram showing the first embodiment and showing torque constants and response characteristics of the valve opening / closing device. FIG. 5 is a diagram illustrating the first embodiment, and is a diagram illustrating forward / reverse rotation torque pulsation when the shift angle is set and reverse rotation torque pulsation of the DC motor 200 of the present embodiment; FIG. 6 shows the first embodiment, and is a connection diagram of a DC motor 300 according to a modification. FIG. 5 shows the first embodiment, and shows the relationship between the torque and the rotation speed of a DC motor 300 according to a modification.

Embodiment 1 FIG.
The present embodiment is directed to an inner rotor type DC motor that is a drive source of a valve opening / closing device, and in which an armature is a rotor and a field is a stator.

  First, the configuration of the valve opening / closing device 100 driven by the DC motor 200 will be briefly described.

  FIG. 1 shows the first embodiment and is a longitudinal sectional view of a valve opening / closing device 100 in which a DC motor 200 is mounted.

  As shown in FIG. 1, in the valve opening / closing apparatus 100, a field 10 (details will be described later) of the DC motor 200 is fixed to the inner peripheral portion of the housing 40. Further, one bearing (for example, a ball bearing) is provided at the axial end of the housing 40 on the valve (not shown) side.

  The case 30 is fitted to the opposite side of the valve of the housing 40. The case 30 is provided with the other bearing (for example, a ball bearing) at the axial end on the opposite side of the housing 40. In addition, a power supply brush 15 (a pair, not shown) that supplies power to the armature 20 is fixed to the case 30.

  An armature 20 (details will be described later) is disposed inside the field 10. The rotating shaft 24 of the armature 20 is supported by the one bearing and the other bearing described above.

  A commutator 26 that contacts the power supply brush 15 while rotating is fixed to the rotating shaft 24. The commutator 26 is electrically connected to an armature coil 22 (described later) of the armature 20 via a connection plate 27.

  A spring case 50 is provided on the valve side of the housing 40. A return spring 60 and a spring receiver 61 are accommodated in the spring case 50.

  A screw shaft 80 (mechanism for converting rotational torque into thrust in the linear motion direction) is screwed onto the rotary shaft 24, and the screw shaft 80 projects from the spring case 50 and is connected to a valve (not shown).

  The valve opening / closing device 100 includes a DC power supply and a control device for supplying an energization signal, although not shown. The control device includes at least a circuit for inverting the applied voltage. The DC power supply is usually provided separately from the valve opening / closing device 100, but the control device may be integrated with or separate from the valve opening / closing device 100.

  2 and 3 are diagrams showing the first embodiment. FIG. 2 is a cross-sectional view of the DC motor 200 (BB cross-sectional view of FIG. 3). FIG. It is AA sectional drawing.

  As shown in FIGS. 2 and 3, the DC motor 200 (DC motor with brush) includes at least a field 10 (stator) and an armature 20 (rotor) positioned inside the field 10. The field 10 is fixed (for example, fixed to the housing 40 of the valve opening / closing device), and the armature 20 rotates inside the field 10. In general, a motor having such a configuration is referred to as an inner rotor type.

  The output of the DC motor 200 is, for example, about 10 to 20 W (watts).

  The present embodiment is characterized by the configuration of the field 10 (stator). First, the armature 20 (rotor) will be described with reference to FIGS.

  4 to 7 show the first embodiment. FIG. 4 is a cross-sectional view of the armature 20 (cross-sectional view taken along the line DD in FIG. 5), and FIG. 5 is a vertical cross-sectional view of the armature 20 (shown in FIG. 4). 6 is a cross-sectional view of the armature core 21, and FIG. 7 is an enlarged plan view of the vicinity of the armature slot 23. FIG.

  As shown in FIGS. 4 and 5, the armature 20 includes an armature core 21, an armature coil 22 housed in an armature slot 23 formed in the armature core 21, and the approximate center of the armature core 21. The rotating shaft 24 fitted in the shaft hole 25 (see FIG. 5) formed in the section, the commutator 26 (see FIG. 1) fixed to the rotating shaft 24, the armature coil 22 and the commutator 26 are electrically connected. And a connection board 27 (see FIG. 1) to be connected to each other.

  As shown in FIG. 6, the armature core 21 has a substantially donut shape in plan view, and a plurality of armature slots 23 are formed at substantially equal intervals in the circumferential direction along the outer peripheral edge. In the example shown in FIG. 6, the number of armature slots 23 is six, but the number of armature slots 23 is not limited to six and may be arbitrary.

  In addition, a circular shaft hole 25 into which the rotary shaft 24 is fitted is formed at a substantially central portion of the armature core 21.

  The armature core 21 is a magnetic steel sheet having a thickness of 0.1 to 1.5 mm (for example, a non-oriented electrical steel sheet (the crystal axis direction of each crystal is set so as not to be biased toward a specific direction of the steel sheet and exhibit magnetic properties). As far as random))) is punched into a predetermined shape, it is laminated in a predetermined number of axial directions (stacking direction) and fixed by punching or welding.

  As shown in the enlarged view of the vicinity of the armature slot 23 in FIG. 7, the armature slot 23 has a substantially pentagonal cross section. The armature slot 23 is opened at the outer peripheral edge of the armature core 21. This opening is called a slot opening 23a. The armature coil 22 (usually a magnet wire having an insulated copper wire surface is used) is inserted into the armature slot 23 from the slot opening 23a.

  8 and 9 show the first embodiment. FIG. 8 is a transverse sectional view of the field 10 (FF sectional view of FIG. 9). FIG. 9 is a longitudinal sectional view of the field 10 (of FIG. 8). EE sectional drawing).

  As shown in FIGS. 8 and 9, the field magnet 10 includes at least a field iron core 11, a field magnet 12 inserted into a field magnet insertion portion 11 a (see FIG. 10) of the field iron core 11, and each field magnet. And a field coil 13 wound for a predetermined turn so as to surround 12 at a substantially right angle with respect to the axial direction.

  The field 10 shown in FIGS. 8 and 9 has, for example, an outer diameter of φ50 [mm] and a pole number of 4 poles.

  The axial length L1 of the field core 11 (see FIG. 9) is preferably longer than the axial length L2 of the armature core 21 (see FIG. 5). This is for efficiently picking up the magnetic flux from the armature 20 side.

  FIG. 10 shows the first embodiment, and is a cross-sectional view of the field core 11. As shown in FIG. 10, the field iron core 11 has a substantially cylindrical shape, and field magnet insertion portions 11a (spaces) corresponding to the number of poles (here, four) are formed along the inner peripheral edge.

  Similarly to the armature core 21, the field core 11 is also an electromagnetic steel sheet having a thickness of 0.1 to 1.5 mm (for example, a non-oriented electrical steel sheet (each crystal so as not to be biased toward a specific direction of the steel sheet and exhibit magnetic properties). Are produced in such a manner that a predetermined number of crystal axes are punched into a predetermined shape, stacked in a predetermined number of axes (stacking direction), and fixed by punching or welding. However, the field iron core 11 may not be a laminate of electromagnetic steel plates. That is, an integral core of magnetic material may be used.

  A field coil storage portion 11 b for providing the field coil 13 is formed between the field magnet insertion portions 11 a of the field iron core 11. The field coil housing portion 11b has substantially the same shape as the arc-shaped field magnet 12. The field coil housing part 11b is open to the inside. The field coil 13 is housed in the field coil housing portion 11b from this opening.

  Furthermore, the outer part of the field magnet insertion part 11a of the field iron core 11 is a cylindrical field back yoke 11c.

  In order to prevent short-circuiting of the magnetic flux of the field magnet 12, a plurality of slits may be provided at both ends of the field magnet insertion portion 11 a or the surfaces facing the armature 20.

  In the example of FIG. 8, one field magnet 12 is provided for one magnetic pole, but it may be divided into a plurality of fields. The axial length of the field magnet 12 is preferably equal to the axial length L1 of the field core 11 (see FIG. 9).

Since the DC motor 200 of the present embodiment is a low output (10 to 20 W) brushed DC motor, a ferrite sintered magnet is used for the field magnet 12. Ferrite sintered magnet is a magnet with excellent cost performance manufactured by powder metallurgy using Fe ₂ O ₃ (ferric oxide) and BaCO ₃ (barium carbonate) or SrCO ₃ (strontium carbonate) as main raw materials. It is.

  FIG. 11 shows the first embodiment, and is an enlarged cross-sectional view of the field magnet 12. As shown in FIG. 8 (see also the enlarged view of FIG. 11), the field magnet 12 is a segment (divided, here divided into four) magnet having a concentric circular arc, but it may be a flat segment and may have any shape. Absent. The magnetization direction may be either a radial direction or a parallel direction, but it is desirable that the magnetization direction be such that the surface magnetic flux density distribution is smoother (has less harmonic components) in accordance with the shape of the field core 11.

  12 to 14 show the first embodiment, FIG. 12 shows the winding direction of the field coil 13, and FIG. 13 shows the winding method (wave winding) of the field coil 13. 14 is a connection diagram of the DC motor 200.

  The field coil 13 is wound one or more turns so as to surround the field magnet 12. For example, as shown in FIG. 12, the field coil 13 is wound (connected) so as to surround the field magnet 12 so that the directions of the current are reversed between the N pole and the S pole.

  That is, the adjacent magnetic poles (field magnets 12) and field coils 13 are wound in opposite directions.

  FIG. 12 shows a case where the direction of the magnetic flux due to the current flowing in the field coil 13 is the same as the direction of the magnetic flux of the field magnet 12.

  A field coil 13 wound around each magnetic pole (field magnet 12) is connected in series. In the winding method, all the magnetic poles may be wound continuously, or each magnetic pole may be wound and connected later.

  When the number of turns of the field coil 13 is small, it may be wound in a wave shape as shown in FIG.

  The wire used for the field coil 13 may be a magnet wire or the like if the field coil 13 has a plurality of turns, and may be a square wire or the like if the field coil 13 is single. In either case, the resistivity is low. Copper wire or the like is preferable.

  As shown in the connection diagram of the DC motor 200 in FIG. 14, the field coil 13 connected in series is connected in parallel to the armature 20 connected to the pair of power supply brushes 15 via the commutator 26. Are connected to the DC power supply 90 in parallel. However, in FIG. 14, the field coil 13 shows only two poles.

  Furthermore, the power supply brush 15 and the commutator 26 are attached at positions where the same energization timing is obtained in any rotation direction.

  The generation of rotational torque when the DC motor 200 having the above configuration is operated will be described.

  Hereinafter, the valve opening direction of the valve opening / closing device 100 is assumed to be normal rotation, and the valve closing direction is assumed to be reverse rotation. The applied voltage (DC power supply 90) is expressed as a positive voltage during forward rotation and as a negative voltage during reverse rotation. When a positive voltage is applied, a current flows along the winding direction of FIG.

  15 to 18 are diagrams showing the first embodiment, and FIG. 15 is a diagram showing the direction of the magnetic flux generated by the field magnet 12 and the direction of the magnetic flux generated by the field coil 13 when the DC motor 200 is rotating forward. 16 is a diagram showing the direction of the magnetic flux produced by the field magnet 12 and the direction of the magnetic flux produced by the field coil 13 when the DC motor 200 is reversely rotated, and FIG. 17 is a diagram showing the relationship between the torque of the DC motor 200 and the rotational speed. FIG. 18 is a diagram showing torque constants and response characteristics of the valve opening / closing device.

  When the valve opening / closing device 100 is rotating forward (DC motor 200), the applied voltage (DC power supply 90) is positive, and a current as shown in FIG. Therefore, as shown in FIG. 15, since the magnetic flux generated by the field coil 13 and the magnetic flux generated by the field magnet 12 face the same direction, the amount of magnetic flux linked to the armature coil 22 can be increased, and the torque constant Becomes larger.

  When the valve opening / closing device 100 is in the valve closing direction (DC motor 200), the applied voltage (DC power supply 90) is negative, and a current in the direction opposite to the current shown in FIG. Therefore, as shown in FIG. 16, the magnetic flux generated by the field coil 13 and the magnetic flux generated by the field magnet 12 face in opposite directions, so that the amount of magnetic flux interlinked with the armature coil 22 is reduced, and the torque constant Becomes smaller.

  Next, the relationship between the rotational speed and torque in each state (during forward rotation, reverse rotation, and no field coil 13) will be described.

here,
(1) Rotational speed (armature 20): N [rad / s];
(2) Torque: T [Nm];
(3) Current (armature 20): I [A];
(4) Applied voltage (DC power supply 90): E [V];
(5) Coil resistance (armature coil 22 (for one phase): R [Ω];
(6) Torque constant: K [Nm / A];
Then, the following equation (1) is established.

N = E / K− (R / K ² ) T (1)
That is, the relationship between the rotational speed N and the torque T is the intercept E / K, the slope of the straight line R / ^{K 2.}

  The actual DC motor 200 also generates a loss torque such as the inductance of the armature coil 22 and the bearing 70 (see FIG. 1). Here, however, the DC motor 200 is small and often negligibly small. I'll omit it.

FIG. 17 shows the relationship between the rotational speed N and the torque T obtained using the equation (1). In FIG. 17, the horizontal axis represents torque (the rotation direction is positive), and the vertical axis represents the number of rotations. In the figure,
(A) In the present embodiment, when the applied voltage (DC power supply 90) is positive (forward rotation);
(B) In the present embodiment, when the applied voltage (DC power supply 90) is negative (reverse);
(C) When the field coil 13 is not provided;
And the magnitudes of the applied voltages are all the same.

In FIG. 17, when the field coil 13 is not provided (c), the relationship between the torque and the rotational speed is the same regardless of whether the applied voltage is positive or negative. On the other hand, in the DC motor 200 of the present embodiment, the torque constant K changes,
(A) When the applied voltage (DC power supply 90) is positive (forward rotation), the stall torque increases and the no-load rotation speed decreases;
(B) When the applied voltage (DC power supply 90) is negative (reverse rotation), the stall torque decreases and the no-load rotation speed increases.
In addition, by providing the field coil 13 in this way, the relationship between the torque and the rotational speed can be freely changed.

  Here, the relationship between the valve opening / closing device 100 and the DC motor 200 of the present embodiment will be described. As described above, the valve opening / closing device 100 has the return spring 60, and the force of the return spring 60 always acts in the direction of closing the valve. Therefore, when the valve is opened, a load is applied in such a direction that the force of the return spring 60 prevents the torque in the rotational direction, and when the valve is closed, the force of the return spring 60 assists the torque in the rotational direction. Therefore, the DC motor 200 requires a larger rotational torque when the valve is opened (= a large torque constant K), and requires a smaller rotational torque when the valve is closed (= a small torque constant K).

  FIG. 18 is a graph showing the torque constant and the response characteristics of the valve opening / closing device, and is a graph showing the response time until the valve opening / closing reaches 100%. In FIG. 18, the horizontal axis represents the torque constant K of the DC motor 200. The torque constant K is standardized as 1 when the field coil 13 is not provided. The right side of the vertical axis shows the response time when the valve is opened, and the left side of the vertical axis shows the response time when the valve is closed. In this example, a 4.0 kg spring is used as the return spring 60.

  As shown in FIG. 18, the torque constant K that gives the shortest response time differs between when the valve is opened and when the valve is closed, and it is necessary to increase the torque constant K when the valve is opened than when the valve is closed. I know that there is.

Further, the wire diameter and the number of turns of the field coil 13 are appropriately determined according to the magnitude of the applied voltage (DC power supply 90), the magnetic circuit of the DC motor 200, and the value of the torque constant K to be changed. For example, when it is desired to change the ± 10% torque constant K with respect to the case where there is no field coil 13, the amount of magnetic flux generated by the field coil 13 is Φe, and the amount of magnetic flux generated by the field magnet 12 is Φm. , So that Φe = 0.1 × Φm,
Φe = AT × P (2)
The winding specifications of the field coil 13 are determined so as to satisfy the above. Here, A is a current flowing through the field coil 13 and is obtained by applying voltage E / field coil resistance. T is the number of turns of the field coil 13, and P is the combined permeance of the magnetic circuit passing through the armature core 21-the magnetic pole (field magnet 12) center-the field back yoke 11c.

  As described above, the DC motor 200 according to the present embodiment can perform an operation according to the load torque characteristics in each rotation direction (forward rotation, reverse rotation) with a simple configuration, and the field 10 and armature 20. In both cases, the degree of freedom of design is widened (it can be downsized), and it is possible to reduce cogging and inertia.

  In addition, by energizing at the same energization timing regardless of the rotation direction, there is no increase in torque pulsation due to phase shift, and the DC motor 200 with less vibration is obtained (see FIG. 19).

  FIG. 19 is a diagram showing the first embodiment, and is a diagram showing forward / reverse rotation torque pulsation when the shift angle is set and reverse rotation torque pulsation of the DC motor 200 of the present embodiment.

  Generally, in a DC motor that rotates only in one direction, the commutator and the power supply brush are shifted by a predetermined angle in order to suppress a decrease in output due to the influence of the inductance of the armature coil. As shown in FIG. 19, when the DC motor is rotated in the reverse direction, for example, a torque pulsation due to a phase shift increases and a phenomenon in which the vibration becomes large occurs.

  On the other hand, the DC motor 200 of the present embodiment is energized at the same energization timing regardless of the rotation direction, so that there is no increase in torque pulsation due to phase shift even in reverse rotation, and there is little vibration. It becomes.

  Next, a modified DC motor 300 will be described with reference to FIGS.

  FIGS. 20 and 21 are diagrams showing the first embodiment, FIG. 20 is a connection diagram of a DC motor 300 according to a modified example, and FIG. .

  The DC motor 300 of the modification is characterized in that the field coil 13 is connected in series with the armature 20 connected to the pair of power supply brushes 15 via a commutator 26 as shown in FIG. To do. It is desirable that the field coil 13 has a lower resistance (thick line). Again, the field coil 13 shows only two poles.

  The torque-rotational speed relationship when the field coil 13 is connected in series with the armature 20 is different from the case where the field coil 13 is connected in parallel with the armature 20, but there is a difference in the stall torque. The no-load rotation number tends to have no difference due to positive / negative of the applied voltage (see FIG. 21).

  When the field coil 13 is connected in series with the armature 20, the current flowing through the field coil 13 ≈ the current flowing through the armature 20. Therefore, on the high speed side, the current is not flown through the entire circuit due to the influence of the induced voltage of the field magnet 12. Therefore, the torque constant K varies with the rotation speed.

  Even in such a case, a motor characteristic corresponding to the load torque can be obtained by producing a difference in the torque constant K up to the middle speed range.

  Further, since the current flowing through the field coil 13 can be suppressed as compared with the case where the field coil 13 is connected in parallel with the armature 20, the amount of heat generated in the field 10 (stator) can be suppressed low. it can.

  10 field, 11 field iron core, 11a field magnet insertion part, 11b field coil housing part, 11c field back yoke, 12 field magnet, 13 field coil, 15 feeding brush, 20 armature, 21 armature core, 22 Armature coil, 23 Armature slot, 23a Slot opening, 24 Rotating shaft, 25 Shaft hole, 26 Commutator, 27 Connection plate, 30 Case, 40 Housing, 50 Spring case, 60 Return spring, 61 Spring receiver, 70 Bearing 80 screw shaft, 90 DC power supply, 100 valve opening / closing device, 200 DC motor, 300 DC motor.

Claims (7)

An inner rotor type DC motor in which the armature is a rotor and the field is a stator,
The field is
A field core formed in a predetermined shape by a magnetic material;
A plurality of field magnets provided at predetermined locations of the field core;
A field coil that is wound a predetermined number of turns so as to surround each of the field magnets at a substantially right angle with respect to the axial direction,
The adjacent field coils are configured to have different current directions ,
The armature includes a rotating shaft,
DC motor the rotating shaft, characterized that you include a mechanism for converting a rotational torque to thrust of the linear motion direction. The field includes a pair of power supply brushes for supplying power to the armature,
The DC motor according to claim 1, wherein the field coil is connected in parallel to the pair of power supply brushes. The field includes a pair of power supply brushes for supplying power to the armature,
The DC motor according to claim 1, wherein the field coil is connected in series to the pair of power supply brushes.   The field coil is continuously wound in a corrugated shape so as to alternately pass between the field magnets as viewed from the inner diameter side of the field magnet and between one axial end and the other axial end of each field magnet. The DC motor according to claim 1, wherein: A return spring that is provided between the valve and the DC motor end and biases the valve in a closing direction; and a spring receiver that holds the return spring. A valve opening / closing device equipped with the DC motor according to any one of claims 1 to 4 . The field coil is configured such that a magnetic flux generated by the field coil and a magnetic flux generated by the field magnet are directed in the same direction during normal rotation that is the valve opening direction of the valve. Item 6. The valve opening and closing device according to Item 5 . The magnetic field coil is configured so that a magnetic flux generated by the field coil and a magnetic flux generated by the field magnet are directed in opposite directions when the valve is reversely rotated in the valve closing direction. 5. The valve opening / closing device according to 5 .

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