JPS6341308B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a step motor that performs stable stepwise rotation.

Figure 1a shows a conventional step motor, here 2
A diagram showing a polar single-phase step motor, and FIG. 1B is a cross-sectional view showing the rotor portion of the step motor. In FIGS. 1a and 1b, reference numeral 1 denotes a cylindrical rotor made of permanent magnets, and a stator 2 made of a magnetic material is arranged around the outer periphery of the rotor. In this case, in order to impart directionality to the rotation of the rotor 1, the stator 2 has an inner periphery at which the rotor 1 is inserted eccentrically relative to the outer periphery of the rotor 1 as shown. 3 is a coil wound around the stator 2, 4 is a transmission wheel, 5 is a tooth thereof, and 6 is a brake lever.

In other words, in such a step motor,
The rotor 1 rotates in steps of 180 degrees in the direction of the arrow in the figure each time the stator 2 is alternately excited to opposite polarities by the coil 3.

FIG. 2b is a diagram showing the operating characteristics of the conventional step motor mentioned above. The shaded area indicates the range in which the motor moves accurately for each step when a pulse voltage as shown in FIG. 2a is applied to the coil 3. The other parts show ranges in which they do not move or move too far and do not operate normally. Note that FIG. 2a shows the pulse voltage (peak value) on the vertical axis and the pulse width on the horizontal axis. In addition, Fig. 2c shows the current (curve i) of the coil 3 when a pulse voltage is applied.
) and the rotational movement of rotor 1 (shown by curve r)
This shows that.

In other words, this type of step motor performs jumping and oscillating movements, so as shown in Figure 2b, the range in which it can accurately step is extremely small, its stability is poor, and when it is incorporated into a device, it is difficult to transmit. There are problems such as a lot of wear on the gear train.

For this reason, conventional measures have been taken, such as increasing stability by engaging the brake lever 6 with the teeth 5 of the transmission wheel 4 that transmits the rotation of the rotor 1 to the driven part, as shown in FIG. 1a. was. That is, the mechanical reaction force generated when the teeth 5 of the transmission wheel 4 overcome the brake lever 6 relieves the impactful rotational force at the beginning of rotation, and after the rotor 1 rotates one step, the inertia If the next tooth 5 of the transmission wheel 4 attempts to overcome the brake lever 6, the inertia force is canceled out by the reaction force generated when the next tooth 5 of the transmission wheel 4 tries to overcome the brake lever 6, thereby preventing overspeeding and preventing the rotation. This provides stability in the forward movement.

However, in conventional step motors that apply braking mechanically, the brake lever 6
Advanced adjustment techniques are required, such as finely adjusting the meshing state between the teeth 5 of the transmission wheel 4 and adjusting the spring force of the brake lever 6, which not only makes it extremely difficult to mass produce, but also makes the transmission wheel 4 There were drawbacks such as wear of the sliding portion of the brake lever 6, changes in the pressing force due to fatigue of the brake lever 6, breakage, etc., and that stable operation could not be expected for a long period of time.

The present invention was made to eliminate the above-mentioned drawbacks, and an object of the present invention is to provide a compact step motor that can operate stably over a long period of time.

Embodiments of the invention will now be described with reference to FIGS. 3a and 3b. FIG. 3a is a partially cutaway view showing an embodiment of a step motor according to the present invention, here a two-pole single-phase step motor, and FIG. 3b is a cross-sectional view showing the rotor portion of the step motor. be. In these Figures 3a and b, 1,
2 and 3 indicate a rotor, a stator, and a coil as in FIG. 1, but in this invention, the structure of the rotor 1 is different from the conventional one, as shown in detail in FIG. 3b. That is, in the figure, 11 is a cylindrical magnet formed of a ferrite magnet, and 12 is a cylindrical magnet 11.
It integrally has a hollow portion 13 at a location located inside the cylindrical magnet 11, and the outer peripheral wall portion is the inner wall 111 of the cylindrical magnet 11.
and a shaft that integrally supports the cylindrical magnet 11 in close contact with the upper and lower end surfaces 112 and 113. 14 is a liquid such as water sealed in an appropriate amount in the hollow portion 13; 15;
is provided in the hollow portion 13 with at least a portion immersed in the liquid 14, and the rotor 1
It is a wing body that rotates together with the aircraft.

Next, the operation of the above-mentioned step motor of the present invention will be explained. That is, when an input pulse voltage as shown in Fig. 2a is applied to the coil 3, the rotor 1 will suddenly start rotating due to the impulsive electromagnetic force generated between the stator 2 and the rotor 1. However,
Here, the liquid 14 tries to maintain a stationary state due to its inertia. Therefore, a relative flow state of the liquid 14 occurs between the rotor 1 and the liquid 14. In other words, the liquid 14 appears to be flowing when viewed from the rotor 1 side. Therefore, the blade body 15, which rotates together with the rotor 1, acts to suppress this flow.
In other words, the liquid 15 on the front side in the rotational direction of the wing body 15 is pressed and has a high pressure, and the pressure on the rear side is conversely low, so this pressure imbalance causes the wing body 15 to
A force is applied to suppress the rotation of the rotor 1, and a braking force corresponding to the rotational speed of the rotor 1 is generated. This braking force suppresses the initially shocking rotational force acting on the rotor 1, so that the rotor 1 starts to rotate gently and overrun is reduced. Furthermore, when the rotor 1 steps from its initial resting position to a position rotated 180 degrees, damped vibration occurs as shown in the last part of the curve r in Fig. 2c, but in this case as well. Similarly to the above, the wing body 1 in the liquid 14
5 moves and stirs the liquid 14, a braking force due to the inertia of the liquid 14 is generated in any direction of rotation of the rotor 1, the vibration state is quickly damped, and the rotor 1 is It will stop faster when it rotates 180 degrees to its normal position.

Note that flow due to inertia is more likely to occur as the viscosity of the liquid 14 is lower and as the mass is larger, so silicone oil with high viscosity is not suitable. In the above example, water with low viscosity was used as the liquid 14, but in addition to this, It is also possible to use materials with large mass and high fluidity, such as mercury.

As explained above, according to the present invention, the rotor 1 is provided with a hollow portion 13, a low viscosity liquid 14 is sealed in the hollow portion 13, and a blade body 15 that rotates integrally with the rotor 1 is provided. Therefore, when the rotor 1 rotates, the inertia of the liquid 14 causes a relative flow between the liquid 14 and the rotor 1, and the blades 15 act to suppress this flow. The braking force suppresses the jumpy and vibratory movement of the rotor 1, resulting in stable stepping motion, and there is no wear and tear on the transmission wheel train, so stable operation can be expected over a long period of time. In addition, as described above, since the liquid 14 and the blade body 15 are provided inside the rotor 1, the structure can be made compact, and
This has the advantage that there is no risk of deterioration, evaporation, or contamination of foreign matter in the liquid 14.

[Brief explanation of the drawing]

Figures 1a and b are diagrams showing a conventional step motor and its rotor section; Figure 2a is a diagram showing a conventional step motor and its rotor;
3A to 3C are diagrams for explaining the characteristics of the step motor, and FIGS. 3A and 3B are diagrams showing an embodiment of the step motor according to the present invention and its rotor portion. 1...Rotor, 13...Hollow part, 14...Liquid such as water, 15...Blade body. Note that the same reference numerals in the figures indicate the same or corresponding parts.

Claims (1)

[Claims] 1 A hollow part is formed inside the rotor, and an appropriate amount of low-viscosity liquid is sealed in the hollow part, and a wing body is provided which rotates together with the rotor and at least a part of which is immersed in the liquid. Step motor.