WO1998024169A1 - Stepping motor - Google Patents

Abstract

A stepping motor in which the rotation of a rotor (22) composed of a permanent magnet can be suppressed in an excellent state even when no drive signal is supplied to exciting coils and which is provided with open loop-like exciting coils (201 and 202) which impress rotating magnetic fields upon the rotor (22) upon receiving excite signals and a closed loop-like braking coil (210) which applies a braking force to the rotor (22) around the rotor (22) in the direction of rotation.

Description

Steppingmo Overnight Technical Field

 The present invention relates to a PM (permanent magnet) type stepping motor, and more particularly to a stepping motor suitable as a drive unit of an indicating instrument. Light

Background art

 PM type stepping dams have been widely used as parts for the Yakuchi field in various industrial fields.Because of their small size and high torque, their use as a drive unit for analog type indicating instruments has been considered in recent years. Have been.

 Many of these types of stepping motors include, as disclosed in, for example, Japanese Patent Application Laid-Open No. 8-149781, a mouth consisting of a permanent magnet having a rotating shaft and a peripheral portion of the rotating direction of the rotor. And two sets of annular stay cores arranged so as to surround each other. Each of the stay cores has an exciting coil wound so as to surround the mouth along the rotation direction, and It consists of an annular yoke with a plurality of pole teeth extended in comb-like fashion facing the peripheral surface in the rotation direction, and applying voltage signals (drive signals) having different phases to each of the two excitation coils. With this, a rotating magnetic field is applied to the mouth through the yoke, and the mouth is driven to rotate.

 By the way, when such a stepping motor is used, for example, as a drive unit of an analog indicating device for a vehicle, it is necessary to rotate the needle connected to the hands by supplying a driving signal according to the measured amount. Although it may be configured, the mouth is not driven by the drive signal supply. Evening drive is not performed. For example, when the power is turned off or the product is transported for Z transport, the rotation of the pointer (pointer) cannot be regulated. Some kind of rotation restricting means is required to keep the position at a predetermined position (eg, the zero point indicating position of the pointer).

As such a rotation restricting means, there is a needle stop which comes into contact with a pointer and suppresses the rotation by contacting with a pointer, or a mouth stop which suppresses the rotation of the pointer, or is fixed to a rotating shaft and rotates together therewith. Rotate the pointer (Ro-Yu) by contacting the dedicated contact member It is conceivable to employ various mechanical restricting means such as a special stopper for suppressing rolling. However, the stepping motor may be provided with a mechanical restricting means simply consisting of such a contact mechanism, because a rotating magnetic field called a detent torque may act even when there is no drive signal supply. In the case of only the needle, the pointer (needle) is likely to move away from the stop position due to the mechanical restriction means due to external factors such as vibration, causing so-called step-out or free move, or the position of the pointer when the product is delivered. However, there are inconveniences such as that the product value varies due to variation in each product.

 For this reason, as disclosed in Japanese Patent Application Laid-Open No. 8-182301, there has been proposed a means for urging and holding a pointer (rotor) at a predetermined position using a suction force by a detent torque. However, since the suction force of the detent torque itself is small, the pointer can easily be lifted by, for example, a slight vibration, and it is conceivable to increase the detent torque as a countermeasure. The mouth does not rotate smoothly during low-speed driving by supplying a driving signal.

 The present invention has been made in view of this point, and it is an object of the present invention to provide a stepping motor capable of satisfactorily suppressing the rotation of the mouth even when no drive signal is supplied to the exciting coil. It is. Disclosure of the invention

 The present invention provides a rotor composed of a permanent magnet, an open-loop exciting coil that is arranged so as to surround the mouth along the rotation direction, receives a drive signal, and applies a rotating magnetic field to the rotor, And a closed-loop braking coil arranged so as to surround the opening along the rotation direction and applying a braking force to the opening.

 Further, according to the present invention, the rotation of the rotor is restricted by predetermined mechanical restriction means, and the rotation is held at the rotation restriction position by the braking force of the braking coil at the rotation restriction position by the mechanical restriction means. It is a feature.

Further, the present invention provides a rotor comprising a permanent magnet, an opening arranged to surround the rotor along the rotation direction and receiving a drive signal supply to apply a rotating magnetic field to the rotor. And a switching means for switching the excitation coil to a closed loop so that a braking force is applied to the rotor when no drive signal is supplied to the excitation coil. .

 Further, according to the present invention, it is preferable that the rotation of the opening is restricted by a predetermined mechanical restriction means, and the excitation coil is switched to a closed loop by the switching means at a rotation restriction position by the mechanical restriction means. The motor is held at the rotation restricting position by power. BRIEF DESCRIPTION OF THE FIGURES

 FIG. 1 is a side view of a stepping motor meter according to a first embodiment of the present invention, FIG. 2 is an exploded perspective view of the stepping motor shown in FIG. 1, and FIG. 3 is a diagram showing an excitation coil and a braking coil of FIG. FIG. 4 is a front view of FIG. 3, showing a winding state of an exciting coil and a braking coil, FIG. 5 is a block diagram showing a driving circuit of a stepping motor type instrument according to the present embodiment, and FIG. FIG. 7 is a perspective view showing an exciting coil and a braking coil according to a second embodiment of the present invention, FIG. 7 is a front view of FIG. 6, showing a winding state of the exciting coil and the braking coil, and FIG. 8 is a third embodiment of the present invention. FIG. 4 is a block diagram showing a driving circuit of a stepping mode meter according to an embodiment of the present invention. BEST MODE FOR CARRYING OUT THE INVENTION

 Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings.

 FIG. 1 is a side view of a stepping motor apparatus in which a stepping motor according to the present invention is applied to an analog indicating instrument as a first embodiment of the present invention, FIG. 2 is an exploded perspective view of the stepping motor apparatus, and FIG. FIG. 4 is a perspective view showing the exciting coil and the braking coil wound on the bobbin of FIG. 2, FIG. 4 is a front view of FIG. 3, showing the winding state of the exciting coil and the braking coil, and FIG. FIG. 3 is a block diagram showing a driving circuit of the evening instrument.

As shown in FIG. 1, a stepping motor type instrument according to the present embodiment has a dial 1 on which a not-shown scale, characters, numerals, figures, and other indicators are formed, and which is fixed behind the dial 1. Stepper motor 2 and this stepper motor It comprises a pointer 3 driven by 2 and a circuit board 4 on which a drive circuit described later for driving the stepping motor 1 is mounted.

 As shown in FIG. 2, the stepping motor 2 has a mouth 22 formed of a permanent magnet having a rotating shaft 21, and a concentric laminated body configured to be housed so as to surround the mouth 22. The first annular stay core 23 and the second annular stay core 24 are arranged facing each other so as to sandwich the annular stay cores 23 and 24 along the axial direction of the rotor 22. The first and second holding members 25 and 26 hold the mouth 22 in the evening cores 23 and 24, and the finger 3 is fixed to the tip of the rotating shaft 21 as shown in FIG. The dial 1 is fixed to the holding member 25 and the second holding member 26 is fixed to the circuit board 4 by caulking, so that the stepping module 1 with the dial 1 and the pointer 3 can be connected to the circuit board 4. It is fixed on the substrate 4. The first and second annular stay cores 23 and 24 have substantially the same configuration, and include annular bobbins 203 and 204 around which the first and second excitation coils 201 and 202 are wound, and a magnetic metal material. And outer yokes 205 and 206, which are substantially annular cup-shaped, and inner yokes 207 and 208 which are also substantially annular plate-shaped, also made of a magnetic metal material. The outer and inner yokes 206, 208 are concentrically stacked so as to sandwich the corresponding annular pobins 203, 204 therebetween, forming first and second annular stay cores 23, 24. The first and second annular stay cores 23 and 24 are concentrically stacked with a spacer 209 made of a non-magnetic metal material interposed therebetween. A surrounding stator body is formed. Each of the outer and inner yokes 205, 206, 207, and 208 is installed inside the annular pobins 203 and 204 in the assembled state, and faces the circumferential surface of the mouth 22 in the rotational direction with an annular comb-shaped arrangement. A plurality of pole teeth 205a, 206a, 207a, 208a are formed.

The first holding member 25 is formed with a rotatable collar 25a that comes into contact with the projection 22a of the mouth 22. The rotatable collar 25a and the projection 22a of the mouth 22 form the mouth. It constitutes a mechanical control device that controls the rotation of 22 overnight. As shown in FIGS. 3 and 4, the lower second annular pobin 204 of the first and second annular pobins 203 and 204 includes, in addition to the second excitation coil 202, Dynamic coil 210 is wound, and the second exciting coil 202 is formed of three terminals 2 1 1, 2 1 2, 2 1 3 protruding from the flange of the annular bobbin 204. One end is connected to terminal 2 11 and the other end is connected to terminal 2 13 to form an open loop.On the other hand, braking coil 210 is connected and fixed to terminal 2 12 at both ends to form a closed loop. The terminals 2 1 1 and 2 13 to which the open-loop second excitation coil 201 is connected and fixed are fixed in the second annular pobin 204 by insert molding. The other end penetrates through the back side of the second annular bobbin 204 and is electrically connected to the circuit board 4 as shown in FIG.

 One end and the other end of the first excitation coil 201 are connected and fixed to the terminals 214 and 215 provided on the opposite sides of the terminals 211 and 213. The first excitation coil 201 also constitutes an open loop, and these terminals 2 14 and 2 15 are also placed in the second annular pobin 204 in the same manner as the terminals 2 1 1 and 2 13. They are fixed by insert molding, and the other ends thereof penetrate the back side of the second annular pobin 204 and are electrically connected to the circuit board 4 as shown in FIG.

 The stepping-monitor-type instrument configured as described above can be driven by the drive circuit shown in FIG. 5.Taking a speedometer for a vehicle as an example, a frequency proportional to the traveling speed, which is a measured amount, will be described. When a signal is input from the input terminal 5, the counting means 6 detects the rise or fall of the input signal and counts it at a predetermined gate time (gate time method), or another high frequency. The clock signal is counted by the input signal (period measurement method), and the ever-changing running speed is calculated as a digital signal.

 The digital data, which is the measurement amount obtained in this manner, is converted into the indicated angle data at a predetermined conversion cycle by the processing means 7, and the difference between the previous indicated angle data and the latest indicated angle data is converted at each conversion cycle. The absolute value and its increase / decrease state are obtained.

 This latest designated angle data is adopted as previous time data in the next update, and the comparison and update with the latest designated angle data are repeated by the same calculation.

The command angle data updated in this manner is subjected to appropriate waveform processing (microstep processing and phase conversion) on the excitation coils 201 and 202 of the stepping motor via the output means 8 to generate a drive signal (voltage signal). As the excitation coil 2 0 1, 2 0 2 are excited, and the magnetic paths are guided through the outer and inner poles 2 0 5, 2 0 6, 2 0 7, 2 0 8 to drive the low speed 22 and the dial 1 The pointer 3 fixed to the rotating shaft 21 is rotated by an angle instruction corresponding to the scale of the arrow.

 The processing means 7 can be configured by a microcomputer including a counting means 6 so as to indicate the traveling speed by arbitrarily setting the instrument indicating characteristics. The power supply to the processing means 7 is performed by a power switch 9. The power is supplied from the power supply 10 via an ignition key switch for an automotive instrument.

 Therefore, when the power switch 9 is on, a voltage, which is a drive signal based on the indicated angle, is applied to the excitation coils 201, 202, and the rotor 22 performs a rotation operation according to the drive signal. However, when the power switch 9 is turned off, a drive signal based on the indicated angle data is not applied to the excitation coils 201 and 202, and it is impossible to control the operation of the rotor 22. It becomes possible.

In this embodiment, the position where the rotor stopper 25a contacts the protrusion 22a of the rotor 22 is set as the base point of the rotor 22 and when the mouth 22 is at the base position. The pointer 3 is fixed to the rotating shaft 21 so that the pointer 3 points to the zero point on the scale, which is the base point of the dial 1, for example. The base position on the side of the step pin damper which is the contact position with the protrusion 2 2a of 2 and the base position of the dial 1 which is the reference base of the pointer 3 are aligned.) In this case, the processing means 7 is a power switch. 9 operates for a certain time immediately after turning off the mouth Isseki 2 2 mouth - Tasutotsuba also has function to perform a process for returning to the contact position between the ₂ 5 _a. Therefore, when the power switch 9 is turned off, the rotation of the pointer 3 is restricted in a state where the pointer 3 indicates the zero point on the dial 1, but in this state, the rotor 2 2 (the finger 3) is vibrated or the like. If the user tries to move, an electromotive voltage is generated in the closed loop shaped braking coil 210, and the magnetic field generated by the electromotive voltage acts as a braking force that suppresses the rotation of the rotor 22. The upper zero point indication state is maintained.

In addition, when the product is transported, for example, in Z transport, and before it is attached to a vehicle that is not connected to the power supply 10, rotation of the pointer 3 due to vibration or the like is suppressed. Problems that vary from one product to another can be suppressed. When the indicated position of 3 is set as the zero point on the dial 1 as described above, the indicated state is maintained.

 The electromotive voltage generated in the braking coil 210 increases as the mouth 22 rapidly rotates, so that the braking force (holding torque) also acts strongly.

 As described above, according to the present embodiment, an open loop excitation coil 20 that receives a supply of an excitation signal and applies a rotating magnetic field to the rotor 22 around the rotation direction of the opening 22 formed of a permanent magnet. By providing the closed loop-shaped braking coil 210 for applying a braking force to the rotor 22, the drive signal is not supplied to the excitation coil 201, for example, the power switch 9 is turned off. When the mouth 22 rotates due to vibration during shipping or product shipment, an electromotive voltage is generated because the braking coil 210 is in a closed loop, and a magnetic field due to the electromotive voltage is generated by the rotor. Acts as a braking force that does not rotate 22. The rotation of the mouth-evening 22 can be suppressed well.

 Also provided is a mechanical restricting means for restricting the rotation of the rotor stopper 25a and the projection 22a of the mouth 22 and the mouth 22, and the braking coil is provided at the rotation restricting position by the mechanical stopping means. By keeping the rotor 22 at the rotation restricting position by the braking force of 210, it is possible to reliably suppress the rotation of the mouth 22 when the drive signal is not supplied.

 In this embodiment, the mechanical restricting means is composed of the rotor stopper 25a and the projection 22a of the rotor 22.However, the mechanical restricting means is composed of the pointer stopper which directly contacts the pointer 3 and suppresses the rotation. Or a dedicated member that is fixed to the rotating shaft 21 and rotates together with the movable member, and the same dedicated member that abuts the movable contact member to suppress the rotation of the pointer 3 (Rotary 22). And a fixed-side contact member made of

Further, in the present embodiment, an example is shown in which the braking coil 210 is wound around the annular bobbin 204 together with the excitation coil 202, but the braking coil 210 is provided around the rotation direction of the mouth 22. If it is wound so as to surround it, it may be wound on a dedicated pobin or winding frame. 6 and 7 show a second embodiment of the present invention. In this embodiment, both ends of a braking coil 210 are connected and fixed to terminals 211, and the effect of such a configuration is the same as that of the first embodiment. Same as the example. FIG. 8 shows a third embodiment of the present invention. In this embodiment, switching means 11 is provided between the output circuit 8 and the terminals 2 1 1 and 2 13. Reference numeral 1 denotes a normally closed reed switch that operates in response to the on / off of the power switch 9. When the power switch 9 is off, the power supply to the drive coil 1 la is cut off, so that switching is performed. The element 11b does not operate and remains in the "closed" state, so that the excitation coil 201 forms a closed loop, while the power supply switch 9 is turned on, and the power is supplied to the drive coil 11a. As the supply is made, the switching element 11b is activated and switched to the "open" state, whereby the exciting coil 201 forms an open loop. The switching means 11 is configured so that when the power switch 9 is turned off from on, the power supply to the drive coil 11 a is cut off and the switching element 11 b is switched to the `` closed '' state. The stepping mode itself is the same as in the first embodiment.

 Therefore, when the power supply switch 9 for switching the excitation coil 201 to the closed loop by the switching means 11 is off, when the rotor is about to rotate due to vibration or the like, an electromotive voltage is generated in the excitation coil 201, and this electromotive force is generated. Since the magnetic field due to the voltage acts as a braking force that does not rotate the mouth 22, the rotation of the mouth 22 can be suppressed well, and the switching means 11 opens the exciting coil 201. When the power switch 9 for switching to the loop is on, no braking force due to the electromotive voltage is generated, and no adverse effect that hinders the rotation operation of the mouth occurs. The mouth 22 can be driven smoothly without any trouble.

 Further, a mechanical restricting means for restricting the rotation of the rotor 22 is provided by the rotor stopper 25a and the projection 22a of the rotor 22, and the rotation is restricted by the mechanical stopping means. 2 is held in the rotation-restricted position by the braking force of the excitation coil 210 switched to the closed loop by the switching means 1 1. Things.

 Such switching means 11 can be provided not only on the exciting coil 201 side but also on the exciting coil 202 side, and may be provided on both the exciting coils 201 and 202. No.

In this embodiment, a normally-closed reed switch is used as the switching means 11. However, a normally open reed switch may be used by devising the circuit configuration, and an analog switch may be used instead of such a reed switch. Industrial applicability

 The present invention is not limited to a stepping motor used as a drive unit of an indicating instrument, and can be widely applied to a PM (permanent magnet) type stepping motor used as a drive component of various devices.

Claims

The scope of the claims 1. A rotor composed of a permanent magnet, an open-loop exciting coil arranged to surround the rotor along the direction of rotation and receiving a drive signal to apply a rotating magnetic field to the mouth, and A closed loop-shaped braking coil arranged so as to surround in the direction of rotation and providing a braking force to the mouth.  2. The rotation of the rotor is restricted by predetermined mechanical restricting means, and is held at the rotation restricting position by the braking force of the brake coil at the rotation restricting position by the mechanical stopping means. The stepping-movement set forth in item 1. 3. A rotor composed of a permanent magnet, an open-loop exciting coil arranged to surround the opening along the direction of rotation and receiving a drive signal to apply a rotating magnetic field to the opening, and Switching means for switching the exciting coil into a closed loop so that the driving force is applied to the rotor when a drive signal is not supplied to the coil.  4. The rotation of the rotor is restricted by predetermined mechanical restricting means, and the rotation restricting position is controlled by the braking force of the exciting coil switched to the closed loop by the switching means at the rotational restricting position by the mechanical stopping means. 4. The stepping motor according to claim 3, wherein the stepping motor is held.