JPS6373864A - Stepping motor - Google Patents

Abstract

PURPOSE:To make a flow rate control accurate and sure by providing a stopper to be fitted to a rotor permanent magnet through using a groove or other mark as a guide and by putting said stopper at a fixed place. CONSTITUTION:A motor-driven expansion value using a stepping motor consists of a valve part V and a stepping motor part M and is composed of a valve body 1 having a needle valve 3 or the like, a stator 8, a rotor 9 and others. In this case, an engaging recess 6a for fixing a place is formed on the outer periphery of a case 6 of the motor part M and an elastic rod 10 having a detent part 19a fitting into said recess 6a is provided at the upper part of said stator 8. Also, a groove-like mark is formed and the rotor 9 is assembled in order that a detent rod 18 as a stopper is erected at the N pole of a permanent magnet 11. Thus, the detent rod 18 of the stopper is surely provided in the center of said permanent magnet 11.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention is directed to a stepping motor that operates a needle valve, etc. of an electric expansion valve (here, the final stop position of the front needle valve is kept constant with high precision). The present invention relates to a stepping motor.

[Conventional technology]

Conventionally, there is a system shown in FIG. 10 in which a stepping motor is used to separate and open the needle valve of a long-bow valve with respect to the valve seat to control the flow rate of fluid.

An electric expansion valve using this stepping motor will be described below.

This electric expansion valve consists of a valve section (2) and a stepping motor section (M). In the valve part (2), a valve seat 2a is provided on the partition wall 2 between the primary port 1a and the secondary port 1b of the valve body 1, and a needle valve 3 moves into and out of contact with the valve seat 2a. 3 is supported slidably in the axial direction within a male screw tube 4 screwed onto the valve body 1 on the side of the secondary roller LB.

A lower cover 5 is provided on the upper part of each valve body 1 with the male screw tube 4 in the center, and a closed case 6 of the stepping motor section M is fixed onto the lower cover 5. Case 6
A stake 8 is removably provided on the outer periphery of the stake 8, which houses a coil 7 and has a large number of widths (or claw poles) 8a arranged at equal intervals in the circumferential direction. A rotor 9 is rotatably supported within the case 6 by the male threaded tube 4. The rotor 9 is constructed by fitting a cylindrical permanent magnet 11 to the outer periphery of the support cylinder 10, and then attaching the upper edge 10a to the permanent magnet 1.
It expands over 1 and integrates both, and the support tube 1
A female threaded tube 12 is fitted and fixed to the inner lower side of the 0 and is screwed onto the male threaded tube 4 so as to be rotatable and movable in the axial direction. The permanent magnet 11 is magnetized with N poles and S poles alternately in the circumferential direction.

A connecting wall 10b is formed in the axially intermediate portion of the support cylinder 10, and the small diameter portion 3a of the needle valve 3 is inserted into the hole 10c of the connecting wall 10b, and then fixed with an E IJ song 3. A crimped coil spring 14 is attached to the small diameter portion 3a of the needle valve 3 at the stepped portion 3.
b and the connection g101).

A shaft 15 fixed to the case 6 at the upper part of the rotor 9
A helical guide ring 16 is wound around the helical guide ring 16, and a slider 17 is engaged with the helical guide ring 16 so as to be able to rotate and move up and down.The outer end of the slider 17 is connected to the rotor 9.
It engages with a locking rod 18 that is set upright.

In the above configuration, when the coil 7 of the stator 8 is energized, the rotor 9 rotates, and the slider 17 moves up and down along the spiral guide ring 16 in accordance with the rotation of the rotor 9, and stops 16a at the upper and lower ends thereof.

Rotation of the rotor 9 and movement of the needle valve 3 stop at the position where it abuts against the needle valve 16b. Also, the needle valve 3 is connected to the valve seat 2a.
When the needle valve 3 is closed, the needle valve 3 is slightly pressed against the valve seat 2a by the spring force of the coil spring 14.

[Problem that the invention seeks to solve]

By the way, the operation will be described in the case where the permanent magnet 11 of the rotor 9 in the stepping motor used in the electric expansion valve has 24 magnetic poles and the coil 7 of the stator 8 is driven by 1-2 phase excitation. Since the permanent magnet 11 has 24 magnetic poles, the distance between the poles of the permanent magnet 11 is 15 degrees, and the distance between the teeth of the stator 8 is 7.5 degrees, so the rotation of the rotor 9 per step is The angle is 3.75
degree.

Now, when a current by 1-2 phase excitation shown in FIG. 4 is applied to the coil 7 of the stepping motor shown in the principle diagram of FIG. 3, the rotor 9 rotates as shown in FIGS. 6 to 9.

That is, FIGS. 6 to 9 show the poles of the teeth of the rotor 9 that move according to the excitation order. This shows the position moved by the excitation of , and the ○ ink pad and the numbers on the side indicate the number of pulses from the origin shown in FIG. Further, it is assumed that the square mark indicates the stopper of the stator 8, that is, the stopper 16b on the fixed side, and the stopper Δ of the rotor 9 cannot move to the right in the figure from the position of the stopper of the stator 8. The figure shows the rotor 9 moving clockwise when viewed from above.

In the case shown in FIG. 6, the stopper Δ of the rotor 9 is provided at the center of the S pole of the permanent magnet 11. Now, focusing on the stopper Δ of the rotor 9, the stopper Δ moves from left to right in accordance with the excitation order of the O stamp numbers shown in the figure. Then, when the number marked with ○ becomes 0, stator 8
The stopper △ of the rotor 9 is located at the stopper of (
condition shown). Furthermore, since the coil 7 continues to be energized, it moves in the order of the numbers with negative numbers. That is, up to -3, it is stopped at the stopper position, and at -4, it is reversed by 15 degrees, and after that, it moves in the same order as before hitting the stopper and returns to 0. In this state, the above operation is repeated every 8 pulses.

Here, when the continuously driven excitation is stopped, the position of the stopper Δ stops at a position indicated by a number from 0 to -8 depending on the phase when the drive is stopped. Therefore, if the phase at which the stopper is to be stopped is determined to be, for example, the A phase, the position at which the stopper Δ stops will be constant, and the stopper will always stop at the position shown in FIG.

Next, the stopper △ of the rotor 9 shown in FIG.
If the stopper △ of the rotor 9 is installed at the center of the N pole of the rotor 9, and the A phase is determined as the phase when stopping, there will be a slight difference between the stopper △ of the rotor 9 and the position △ shown by the broken line in Fig. 7. Stator 8
It will stop at two positions, the stoppama position and the stoppama position.

The slight difference here refers to a difference in the relative relationship between the stopper of the rotor 9 and the stopper of the main body, and a difference in factors such as applied current that do not affect the torque.

When the current changes, the equilibrium position changes. Therefore, if the stopper △ of the rotor 9 and the stopper of the stator 3 are
Even if a rotor 9 is used that has high rigidity against the torque of It happens. Therefore, if the stopper Δ of the rotor 9 is provided at the center of the N pole of the permanent magnet, the rotor 9 cannot be stopped at a fixed position.

3 and 9 show the case where the stopper Δ of the rotor 9 is provided between the N pole and the S pole of the permanent magnet 11,
In this case, if the drive pulse is stopped at the A phase, the stop position of the stopper Δ of the rotor 9 becomes constant. However, in any case, due to the damping characteristics of the rotor 9, this is no longer the case when the rotor 9 overshoots during reversal and moves in the opposite direction for 8 or more pulses in the next pulse.

As is clear from the above explanation, when detecting the position of a stepping motor by installing a stopper in the rotation direction,
The accuracy of the origin for positioning consists of the following three items.

(1) Keep the excitation phase constant when stopping the drive.

(2) Improving damping characteristics during reversal.

(3) The relative positions of the N and S poles of the permanent magnets 11 of the rotor 9 and the magnetic pole teeth of the stator 8 are set so that the rotor 9 does not reverse in the excitation phase when the drive is stopped.

By the way, item (1) above can be solved using the software of the city control circuit, and item (2) can be solved by considering frictional resistance, changes in inertial load, damping by the drive circuit, and damping characteristics. This can be solved by software, such as slowing down the excitation speed at initialization after one fish, or reducing the speed only when the excitation &u N% is about to expire at initialization.

However, item (3) cannot be solved unless the stopper Δ of the rotor 9 is provided near the center of the S pole of the permanent magnet 11 (away from the N pole).

Therefore, the present invention allows the stopper Δ to be reliably and easily provided at the center of the permanent magnet 11 Stl.

[Means for solving problems]

The present invention solves the above-mentioned problems.In order to keep the relationship between the magnetic pole position of the permanent magnet of the rotor and the tooth position of the stake constant when the load is stopped, marks are placed on the permanent magnet in advance so that the stopper can be set at a predetermined magnetic percentage. This means that the rotor stops at a constant position when the load stops in a stepping motor that mechanically stops the rotation of the rotor with a stopper or the like to stop driving the load. Attach a stopper that is attached to the permanent magnet of the rotor using a mark such as a groove formed on a predetermined magnetic pole as a guide, and align the stopper with respect to the position of the stator teeth and the position of the rotor magnetic pole. This is accomplished by a stepping motor that is characterized by a constant position.

〔Example〕

A valve using a stepping motor according to the present invention has a structure as shown in FIG. 1 in contrast to the conventional example described above.

In other words, the difference from the conventional example shown in FIG. 10 is that case 6
Four engaging parts 6a for position fixing are formed at desired positions on the outer periphery of the stake 8, and on the other hand, an elastic rod 19 having a locking part 19a that engages in the engaging recess 6a is provided on the upper part of the stake 8. 19a
was installed so that it coincided with the 5m tNNa2O centerline of stake 8.

In addition, in the present invention, in order to erect the locking rod 18 serving as a stopper at N''% of the permanent magnet 11, as shown in FIG.
), as shown in (b), a mark 11a such as a groove is formed in one place of the cylindrical magnet 11a, and this mark 11a
is magnetized so that it becomes the north pole, and then the mark ll
The locking rod 13 is erected on the lever 13, and the rotor 9 is assembled, or the locking rod 18 is erected in advance at one place of the cylindrical magnet, and then the rotor 9 is erected. This is a characteristic feature.

Next, the method of assembling the stepping motor valve according to the present invention will be described. First, the rotor 9 is rotated, and the needle valve 3, which is moved up and down by the rotor 9, is lowered to a desired position.

Next, the slider 17 is rotated and lowered to a desired position in the same manner as the rotor 9, and then the case 6 is placed over the rotor 9 with the locking rod 18 in contact with the slider 17. Then, the case 6 is covered with a jig configured in the same manner as the stator 8 described above, that is, having a locking portion 19a.

In this state, a pulse signal (the number of pulses that is greater than the number of pulses that causes the rotor 9 to change the needle valve 3 from fully open to fully closed) is applied to the coil of the jig to rotate the rotor 9 in the direction in which the needle valve 3 closes. let As a result, the needle valve 3 closes the valve seat 2a, and the rotor 9 closes the guide ring 1.
Since the locking rod 18 rotates the slider 17 by the spring force caused by the needle valve 3, the needle valve 3 rotates a little even after the valve seat 2a is closed. Then, this state becomes the origin of the beginning.

Next, a pulse signal of a desired frequency in the direction of opening the valve is applied to the coil of the jig. As a result, the rotor 9
is rotated in the opposite direction to that described above, and the needle valve 3 is separated from the valve seat 2a, and the valve is slightly opened. At this time, the jig is rotated so that the flow rate of the fluid flowing through the valve becomes a preset flow rate. In other words, when the jig is rotated with voltage applied to the coil in the jig, the rotor 9 in the case 6
Since the valve rotates together with the jig and the opening degree of the valve changes, this adjustment is performed to obtain the preset flow rate.

Once the opening degree of the sniff valve is adjusted from the original state so that the flow rate when a pulse signal of a predetermined frequency is applied becomes the predetermined flow rate, the jig is then removed from case 6. Then, the opening of the case 6 and the lower cover 5 are welded and fixed. This allows the locking part 19a of the stator 8, which is configured in the same way as the jig, to be connected to the engagement recess 6a of the case 6.
When the stator 8 is engaged and fixed, the positional relationship between the valve part (2) in the closed state and the stator 8 is always the same. Therefore, even if the valve section (2) and the morph section M are separated for reasons such as replacing the coil 7 in the stator 8, the positional relationship between the two always remains the same.

In the above-mentioned embodiment, the positioning of the valve part (1) and the stator 8 was explained using the locking part 19a of the stator 8 and the engagement recess 6a of the case 6. This may be done, for example, by aligning the mark displayed on the case 6 and the mark displayed on the stator 8. In this case, the valve part (2) and the motor part M may be fixed by various methods such as welding. It is also conceivable to form a screw on the outer periphery of the core 15 and to form a screw hole in the top of the case 6 so that the aforementioned adjustment can be carried out by screwing the core 15 together. Note that after the adjustment, the mandrel 15 is fixed to the case 6 by welding or the like.

As described above, in the present invention, the magnetic pole of the permanent magnet 11 of the rotor 9 to which the locking rod 18 is attached is always a constant pole (5Th in this embodiment). 9 will always stop at a fixed position.

In the above embodiment, the locking rod 18 is connected to the permanent magnet 1.
Although the explanation has been given on the case where the locking rod 18 is mounted on the center of the S pole of the locking rod 18, this mounting position is determined by the state of the excitation current to the coil 7 of the stator 8, so the mounting position of the locking rod 18 is controlled. Determined in relation to the circuit.

〔Effect of the invention〕

As described above, in a stepping motor in which the rotation of the rotor is mechanically restrained by a stopper or the like to stop driving a load, the permanent magnets of the rotor are fixed so that the rotor stops at a constant position when the load is stopped. The stopper to be attached is attached using a mark such as a groove formed on a predetermined magnetic pole as a guide, so that the position of the stopper is constant with respect to the position of the teeth of the stake and the position of the magnetic pole of the rotor. When this stepping motor is used in an electric control valve, the position of the needle valve with respect to the valve seat is always constant, and the flow rate can be controlled accurately and reliably.

[Brief explanation of the drawing]

Fig. 1 is a sectional view of the stepping motor of the present invention applied to an electric expansion valve, Fig. 2(b) is a plan view and a side view of the permanent magnet incorporated in the above stepping motor, Fig. 3 is a diagram showing the relationship between the permanent magnet and the coil, Fig. 4 is a diagram showing the inversion order to the same coil as above, and Fig. 5 is a diagram showing the rotation angle of the rotor with respect to the number of pulses.
6 to 9 are exploded views showing the relationship between the stator and rotor in consideration of the relationship with the stopper, and FIG. 10 is a sectional view of a conventional electric expansion valve. DESCRIPTION OF SYMBOLS 1... Valve body, 2a... Valve seat, 3... Needle valve, 6... Case, 6a... Engaging part, 7... Coil, end... Stator, 8a... Teeth, 9...Rotor, 1
1... Permanent magnet, 16a, 16b... Stopper, 1
8...Latching rod. Patent Applicant: Saginomiya Seisakusho Co., Ltd. Figure 1-Status Figure 7 Figure 8 X Poots Figure 9

Claims (1)

[Claims] In a stepping motor that mechanically stops the rotation of the rotor using a stopper or the like to stop driving the load, the stopper attached to the permanent magnet of the rotor is predetermined so that the stop position of the rotor remains constant when the load is stopped. A stepping motor characterized in that a mark such as a groove formed on a magnetic pole is attached as a mark so that the position of the stopper is constant with respect to the position of the teeth of the stator and the position of the magnetic pole of the rotor.