JPH0442074A - Detecting head feeding mechanism - Google Patents

Abstract

PURPOSE:To safely protect even if driving means runs away and a detecting head is brought into contact with an element to be measured and to obtain a suitable measuring accuracy by transmitting driving force of the means to a holder for supporting the head through transmitting torque adjustable engaging means. CONSTITUTION:Engaging means 34 provided on the upper surface of a holder 22 for supporting a detecting head 10 engages a threaded shaft 30 connected to the output shaft of a stepping motor 28 with thread grooves 32. A partial engaging pin 44 is composed to be elastically press-engaged with the grooves 32 through a compression coil spring 48 nd a leaf spring 38, and this pressing force is adjustable by adjusting threads 40. Accordingly, the driving force of the output shaft of a motor 28 can be set within predetermined transmitting torque so that the holder 22 for supporting the head 10 moves by a suitable thrust. When the motor 28m runs away and the head 10 collides with a rotor, etc., the pin 44 rides over threads to generate a slide to the shaft 30, thereby limiting a torque. Accordingly, power is not transmitted from the motor 28, nd the movement of the holder 22 is prevented. Thus, the head 10 is safely protected without damage.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] This invention relates to a detection head feeding mechanism, and in particular, this detection head is used for linearly moving a holder supporting a magnetic detection head relative to an object to be detected. The present invention relates to a detection head feeding mechanism configured to transmit the driving force of a rotational drive means to the holder via an engagement means whose transmission torque can be adjusted.

[Background Art] In recent years, with the rapid development of audio equipment, video equipment, computers, etc., there is a growing demand for higher quality as their performance improves.

In particular, motors installed in AVi equipment (audio visual equipment) are required to have small rotational irregularities, high efficiency, and stability.

However, as for the drive method, the direct drive method is beginning to attract attention, and a motor with low speed and extremely small rotational irregularity is required, and the axial flux brushless motor is the best motor to meet this requirement. This motor is commonly used in AVII devices.

In other words, as shown in the overall cross-sectional views of brushless motors in FIGS. 6(a) and 6(b), the most commonly used 3-phase bipolar 8-pole brushless motor has a small external dimension in the axial direction compared to its diameter. It has a flat structure.

In this case, the rotor 62 is formed of a disc-shaped magnet, and has a magnetized configuration called an axial flux, which is magnetized in the direction of a rotating shaft 62b perpendicular to the disc.

One of the rotating shafts 62b of the rotor magnet 62a is rotatably supported via bearings 67a and 67b inserted into the boss 65a of the housing 65.

Further, an iron substrate (hereinafter referred to as a yoke 98) is fixed to the upper surface of a flange 65b formed on the housing 65, and six fan-shaped coils 96 are arranged in the shape of orange slices on the upper surface of the yoke 98, which becomes an insulating surface 98a. A stator 97 is configured.

The lower surface of the rotor magnet 62a is magnetized in an eight-pole fan shape, and the rotor magnet 62a is supported so as to form a slight gap δ between the magnetized surface 62c and the plane of the coil 96 of the stator 97. Ru. In addition, the coil 96 has a positional relationship of ±7.5° with respect to the position where the centers of the magnetic poles and the coil 96 overlap, so that the torque generating conductor (straight line part) of the coil 96 overlaps with the boundary part of the magnetic pole, and the coil 96 Since the generated torque becomes unstable, it is disconnected from the motor circuit.

On the other hand, one phase of the six coils 96 is obtained by connecting two coils 96 that face each other in series around the rotor shaft 62b, and two phases that do not meet the above conditions are connected in series, and the magnetic pole ( The direction of the current is controlled so that rotational torque is generated in one direction depending on the N pole, Si).

In this type of motor, the coil of one phase out of the three phases is always at rest, and this switching is performed by the driver IC every time the rotor 62 rotates 15 degrees.

That is, torque is generated by each coil 96 simultaneously acting on all magnetic poles of the rotor magnet 62a, and as the rotor magnet 62a rotates, the armature current flows through the coils forming one pole. 96 to the coil 96 forming the next pole, and each coil takes charge of generating torque in turn.
The coil current of one pole is switched between positive and negative directions depending on the polarity of the approaching magnetic pole, and the switching of this current between positive and negative is performed at a synchronous frequency determined by the number of poles of the rotor magnet and the rotational speed of the motor.

In addition, since the torque varies depending not only on the strength of the main magnetic flux and the current in the coil, but also on the relative positional relationship between the magnetic poles and the coil 96, the relative positional relationship between the magnetic poles of the rotor magnet 62a and the coil 96 due to the rotation of the rotor magnet 62a changes. The current in each coil must be appropriately controlled according to the change, so that the torque generated at any moment is always constant.

In this case, when the torque changes depending on the positional relationship of the rotor magnets 62a, the rotational speed of the motor changes instantaneously, causing so-called wow and flutter. Since this wow and flutter is fatal to the AV motor, it is necessary to suppress torque fluctuations as much as possible.

This control is performed by the Hall element 100 and the coil current control circuit.
The position of the magnetic pole of a is detected, and based on that signal, an electronic circuit distributes the appropriate current to the coils of each phase.

Here, in order for the torque generation sequence to be performed accurately, the arrangement positions of the magnetic poles and Hall elements 100 must be accurate. This disturbs the periodicity of the sequence for controlling the coil current, causing the torque to fluctuate over time within one revolution of the motor.

Further, as the rotor magnet rotates, the magnetic poles that generate torque change sequentially, but if there is any unevenness in the magnetization of the magnet, this can immediately cause fluctuations in the rotational speed.

In this case, it is necessary to measure the magnetization distribution state of the rotor magnets of various brushless motors in advance and collect data on magnetic flux density.

Therefore, when measuring the magnetization distribution of the rotor magnet 62a, the detection head of the magnetic flux density measuring device is moved at a constant speed in the radial direction relative to the rotor magnet 62a by the feeding mechanism while the rotor magnet 62a is rotating at a constant speed. The output voltage of the detection head was then determined as a measurement value.

[Problems to be Solved by the Invention] Such a detection head feeding mechanism has a structure in which the output shaft of the drive means and the holder that supports the detection head are screwed together. If something goes out of control and the screw shaft end comes off, or if the detection head collides with the object to be measured, such as the rotor, the detection part of the detection head will be damaged or broken, and the measurement accuracy will be affected. However, this method has the disadvantage that the detection rate decreases or becomes undetectable.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to transmit the driving force of the driving means to the holder that supports the detection head through the engagement means whose transmission torque can be adjusted. Even if the detection head detaches from the screw shaft end due to runaway or comes into contact with the object to be measured, the resulting impact force or excessive torque will not be directly transmitted to the detection head and will be safely protected. The object of the present invention is to provide a detection head feeding mechanism that can obtain appropriate measurement accuracy by doing so.

[Means for solving the problem] In order to achieve the above object, a holder supporting a detection head on a movable support base in a direction perpendicular to the direction of movement of the support base is moved forward and backward via a feeding mechanism. The detection head feeding mechanism of the present invention includes a rotary drive means fixed to the support base, a screw shaft extending on the output shaft axis of the rotary drive means, and elastically pressed against the screw shaft. and an engaging means provided on the holder to engage the holder, and the engaging means is configured to be able to adjust the pressing force against the thread groove so that the holder obtains a predetermined transmission torque with respect to the power of the rotational drive means. It is characterized by

In this case, the rotational driving means includes a stepping motor, and the holder is provided with an engaging member that elastically presses and engages with the threaded arm so as to transmit the rotational driving force of the stepping motor as power in the linear direction of the holder. , this engagement member includes an engagement pin implanted in the block to engage with the thread groove, a plate spring fixing the block to the free end, a compression coil spring that presses the block, and the compression coil spring. It is preferable if it is constructed with a screw shaft that adjusts the pressing force of the coil spring.

[Operation] The detection head feeding mechanism according to the present invention is configured to transmit the driving force of the driving means to the holder that supports the detection head via the engagement means whose transmission torque is adjustable. When the detection device that detects the end of the movement of a holder moved by a stepping motor does not operate and the motor runs out of control, causing the stepping motor to cross the end of the threaded shaft, or when the detection head hits the object to be measured, etc. When this happens, the leaf spring bends and the engagement pin climbs over the helical ridge, causing slippage between it and the screw shaft, which limits the torque.

Therefore, no more power is transmitted from the motor side.
The movement of the holder is still prevented, thereby ensuring safe and appropriate measurement accuracy without damaging or breaking the detection head.

[Embodiment] Next, an embodiment of a detection head feeding mechanism according to the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is an overall view of a detection head feeding mechanism showing an embodiment of the present invention.

In this figure, reference numeral 10 indicates a detection head, and a feed rod 24 for moving the detection head 10 forward and backward with respect to a rotor 62, which is an object to be measured, is configured as follows.

That is, a support 16 erected on a horizontal base 14,
A moving platform 20 that engages with a linear guide rail 18 fixed to the front side of the support column 16 and is guided so as to be movable up and down;
An L-shaped support base 19 fixed on the moving base 20,
A holder 22 that is slidably guided by a linear guide rail 26 (see FIGS. 4 and 5) fixed to the upper surface of the horizontal surface of the support base 19 and that supports the detection head 10 therethrough, and A stepping motor 28 as a rotation driving means attached to a side surface, a screw shaft 30 connected to an output shaft (not shown) of the stepping motor 28, and a holder to be engaged with a thread groove 32 of the screw shaft 30. 22 and a retaining means 34 provided on the horizontal plane (see FIG. 3).

On the other hand, as shown in FIG. 1 and FIG. The magnetic detection head 10 is screwed into a nut 21 fixed to the side surface, and the magnetic detection head 10 can be moved up and down together with the holder 22 by manually rotating the screw shaft 15.

As shown in FIG. 3, the engaging means 34 provided on the upper surface of the holder 22 is horizontally positioned to face the L-shaped bracket 36 fixed to the upper surface of the holder 22 and the vertical piece of the L-shaped bracket 36. Leaf spring 3 fixed vertically at the end of the piece
8, an adjustment screw 40 that is screwed into a screw hole passing through the vertical piece of the bracket 36 and has a knob 39 at its tip, and a leaf spring 38.
The block 4 is fixed to the inner surface of the block 4 and has an engaging pin 44 implanted therein.
6, and a compression coil spring 48 inserted between the flange 42 at the tip of the adjusting screw 40 and the block 46 to press the block 46.

In this case, the engaging pin 44 provided on the block 46 is designed to engage with the screw 32 screwed on the outer periphery of the screw shaft 30.
It is slightly inclined to match the lead angle of this thread groove 32. Further, the engagement pin 44 is screwed by the action of the biasing force of the compression coil spring 48 and the leaf spring 38. l! 32
It is configured to be elastically pressed into engagement with. The pressing force of the engaging pin 44 can be adjusted by rotating the adjusting screw 40 (see FIG. 3).

Therefore, the detection head 10 has a holder 22 that supports it.
The driving force of the output shaft of the stepping motor 28 can be set within a predetermined transmission torque so that 'jM moves with a positive thrust force.

However, if the stepping motor 28 or the like runs out of control and exceeds the end of the screw shaft 30, or if the detection head 10 collides with the rotor 62 or the like, the engagement pin 44 will go over the thread and cross the screw shaft 30. Torque is limited due to slipping between the two.

In this case, the main body portion 13 of the detection head 10 is attached to the holder 22.
The detection head 10 is inserted and held through a sleeve 52 inserted into a through hole 50 formed in the detection head 10, and the tip portion of the detection head 10 is axially positioned at an appropriate position with respect to the rotor 62.

In this embodiment, the detection head 10 uses a magnetic detection head provided with a Hall element (not shown) at the tip of the probe 11, and the object 62 is a magnetized rotor magnet 62 used in an axial flux type brushless motor.
a is used.

When detecting the magnetization distribution of the rotor magnet 62a, the tip of the probe 11 is connected to the rotor magnet 62a.
It is possible to set an appropriate initial position by appropriately moving forward and backward in the axial direction with respect to a.

In this case, the tip of the probe 11 and the rotor magnet 62
The vertical spacing of a with respect to the magnetized surface 62c of the rotor 62 is determined to be appropriate for the detected magnetized surface 62c of the rotor 62 by manually rotating and finely adjusting the screw shaft 15 rotatably installed on the base 14. Can be set to .

The magnetic detection head 1 set in the proper position in this way
Magnetic measurement is performed by moving the probe 11 in the axial direction by the stepping motor 28 with respect to the rotor 62 that is rotationally driven.

The linear movement end of the probe 11 is connected to a dog 33 fixed to the lower surface of the holder 22, and a pair of limit switches 35a and 3 arranged on the front surface of the support base 19 to detect the dog 33.
5b detects the forward and backward movement end of the detection rod 10 (
(See Figures 1 and 2).

In this case, a rotary encoder (not shown) is provided at the end of the main shaft that supports the lower end of the rotating shaft 62b of the rotor 62, and generates pulses divided into a plurality of pulses for one rotation of the rotor 62, and When the measurement for one rotation of the probe 62a is completed, the probe 11 is moved one step in the radial direction. By sequentially performing this process, it is possible to accurately measure the magnetic distribution state on the coordinate-divided rotor.

In this way, the holder 22 supporting the magnetic detection head 10
By configuring the engaging means 34 that engages with this to elastically engage with the groove of the screw shaft 30 of the stepping motor 28 serving as the driving means, the transmitted torque is appropriately limited and a stable detection head is created. feed control is achieved.

[Effects of the Invention] As is clear from the embodiments described above, the detection head feeding mechanism according to the present invention applies the driving force of the driving means to the holder that supports the detection head.

By configuring the transmission torque to be transmitted through an adjustable engagement means, even if the driving means such as a stepping motor goes out of control and the detection head comes into contact with the object to be measured, the detection head will not be damaged or damaged. Since it is safely protected, appropriate measurement accuracy can be obtained, and furthermore, the feed a! No unreasonable acting force is generated on the l structure, it is safe and reliability as a measuring device can be ensured, and the stability of the detection device can be maintained over a long period of time.

Although the preferred embodiments of the present invention have been described above, it is needless to say that the present invention is not limited to the above-described embodiments and that various design changes can be made without departing from the spirit of the present invention.

[Brief explanation of drawings]

FIG. 1 shows an embodiment of the present invention, and FIG. 2 is an overall perspective view of the feeding mechanism of a detection head used in a magnetic distribution detection device. FIG. 3 is a partial perspective view of the feeding mechanism. 4 is a sectional view taken along the line A-A in FIG. 1, FIG. 5 is a view taken along arrow B in FIG. Figure 6(b) is similar to Figure 6(a)
) c-cI! It is a JT side view. 10...Detection head 11...Probe 18.
26...Linear guide rail 19...Support stand 20...Movement stand 21...
・Nut 22...Holder 24...Feeding mechanism 28...Rotation drive means (stepping motor) 30・
... Screw shaft 32 ... Screw eraser 34 ... Engagement means 36 ... To L-shaped bracket 1 38 ... Leaf spring 40 ... Adjustment screw 44 ...
...Engagement pin 46...Block 48...Compression coil spring 62...(rotor) measurement object 62a...rotor magnet 62b...rotor shaft 62c...magnetized surface 96...
... Coil 98 ... Yoke 97 ... Stator 100 ... Hall element

Claims (2)

[Claims] (1) In a detection head feeding mechanism configured to move forward and backward via a feeding mechanism a holder in which a detection head is supported on a movable support in a direction orthogonal to the direction of movement of the support, the a rotary drive means fixed to a base; a screw shaft extending on the output shaft axis of the rotary drive means; and an engaging means provided on the holder to elastically press and engage the screw shaft. A detection head feeding mechanism, characterized in that the engagement means is configured to be able to adjust the pressing force against the thread groove so that the holder obtains a predetermined transmission torque with respect to the power of the rotational drive means. (2) The rotational driving means includes a stepping motor, and the holder is provided with an engaging member that elastically engages with the thread groove so as to transmit the rotational driving force of the stepping motor as power in the linear direction of the holder. , this engagement member includes an engagement pin implanted in the block to engage with the thread groove, a leaf spring fixing the block to the free end, a compression coil spring that presses the block, and the compression coil. 2. The detection head feeding mechanism according to claim 1, further comprising a screw shaft for adjusting the pressing force of the spring.