JPH03212150A - Linear pulse motor - Google Patents

Abstract

PURPOSE:To accurately and smoothly position by rocking a primary side magnetic circuit by a specific amount on a plane in the advancing direction by driving means. CONSTITUTION:A primary side magnetic circuit 1 is rocked in the advancing direction on a plane according to an equation by driving means 5. That is, the circuit 1 is always attracted to a secondary side magnetic circuit 3 by magnetic attraction forces of permanent magnets 13, 14, the suction force is received by a thrust bearing 4 to be oscillated. Then, a current flows to an electromagnet 5-1, the circuit 1 is attracted in parallel to the circuit 3. Then, when a movable unit is moved and to a region to be accurately and smoothly positioned, if the current of the magnet 5-1 is interrupted, the circuit 1 is equivalent to the case with a skew of only tau/4 (m=2, n=4) to the circuit 3 by a return spring 5-2. Thus, the region to be accurately and smoothly positioned can be easily altered.

Description

[Detailed Description of the Invention] [Summary] Regarding linear pulse motors used in robots, conveyance devices, etc., they do not need to be high speed, but they have high accuracy (smooth positioning and a degree of freedom that allows easy change of the area that must be moved). In order to provide a linear pulse motor with high speed, the primary side magnetic circuit is movably supported on the fixed side secondary side magnetic circuit, and the frame is provided with a frame that supports the primary side magnetic circuit so as to be movable on the fixed side. A support that can swing freely by 2τ/n-m (where the pitch of teeth, m is the number of phases of the motor, and n is the order of harmonics to be canceled with respect to the fundamental wave of the period of τ) on a plane. and a drive means for swinging the primary side magnetic circuit.

[Industrial application field]

TECHNICAL FIELD The present invention relates to a linear pulse motor used in robots, conveyance devices, and the like.

The long secondary magnetic circuit of a linear pulse motor (hereinafter referred to as LPM) used in robots, conveyors, etc.
There are areas where the primary side magnetic circuit needs to operate at high speed and areas where it does not need to be operated at high speed but must be accurately and smoothly positioned, and it is desired to provide an LPM that can freely vary this latter area. There is.

[Conventional technology]

FIG. 4 is a configuration diagram of a conventional LPM, FIG. 5 is a diagram showing an example of the tooth shape of a secondary side magnetic circuit, and FIG. 6 is an explanatory diagram of an example of full step drive.

The LPM consists of a movable part and a fixed part, as shown in Figure 4.
The movable part has two sets of magnetic poles each having two sets of rectangular teeth arranged at equal pitch intervals, and each magnetic pole is equipped with a permanent magnet 13.14 that provides magnetic flux and an excitation coil 15.16. The two permanent magnets 13 and 14 movably support the primary magnetic circuit l and the primary magnetic circuit ■ connected to the yoke 12, respectively, on the fixed secondary magnetic circuit 3. It consists of two aluminum frames.

The frame 2 is provided with a radial bearing 10 for supporting the cap and a radial bearing 11 for the linear guide, which move the movable part linearly.The secondary magnetic circuit 3 includes a primary magnetic circuit. It has teeth with the same pitch as 1.

There are two main types of driving LPM: full-step driving and micro-step driving.

To explain full-step drive using an example of a two-phase, one-phase drive in which there are two excitation coils that flow different currents, as shown in FIG. , then a current in the forward direction is passed through the excitation coil 16, then a current in the opposite direction is passed through the excitation coil I5, and then,
The process of passing a current in the opposite direction through the excitation coil 16 is repeated in sequence.

Then, assuming that the pitch of the teeth is τ, the teeth of the primary magnetic circuit 1 are initially aligned with the teeth of the secondary magnetic circuit 3 as shown in FIG. Advance by 4, then advance by τ/2 as shown in C, then advance by 3τ/4 as shown in 2,
The next position is advanced by τ as shown in A, and can be advanced sequentially and driven at high speed.In the case of microstep drive, the current flowing through the excitation coil 15 on the l-phase side and the excitation coil 16 on the 2-phase side is , sine wave, and cosine wave with amplitude respectively.

It changes with a cosine wave, keeps the thrust constant, and changes the phase little by little, so that the primary magnetic circuit advances little by little.This allows for high resolution and precision positioning, and smooth, vibration-suppressed positioning. Although it can be operated, it is necessary to increase the pulse frequency for high-speed operation, which makes the control circuit complicated and difficult.

Next, a problem when the teeth of the secondary side magnetic circuit 3 are rectangular will be explained.

If the teeth of the secondary magnetic circuit 3 are rectangular as shown in FIG. A detent force of 4 τ/4 cycles is generated and is superimposed on the thrust force generated by the current when the coil is excited, distorting the thrust waveform, lowering the resolution and accuracy of positioning, and making the operation vibratory.

Therefore, in order to prevent this problem by changing the shape of the teeth to be stepped or skewed as shown in FIG. A patent application was filed for a linear pulse motor in Japanese Patent Application No. 189329/1989 on July 28th, and problems caused by detent force can be prevented by making the tooth shape stepped or skewed as shown in Figure 5. However, in this case, in order to cancel the harmonics, the peak value of the thrust decreases, and the acceleration and load driving ability decrease.

Therefore, although high speed is not required, accuracy (in areas where smooth positioning is required, the secondary magnetic circuit 3
The shape of the teeth is, for example, skewed as shown in FIG. 5, and microstep drive is performed, and in areas where high-speed operation is required, the teeth are rectangular and full step drive is performed.

[Problem to be solved by the invention]

However, although the above conventional method does not require high speed, when you want to change an area that must be moved precisely and smoothly, it cannot be changed, and there is a problem that the degree of freedom for the application is limited. .

The present invention aims to provide an LPM with a high degree of freedom, which does not require high speed, but can easily change a region that must be moved accurately and smoothly.

[Means to solve the problem]

FIG. 1 is a diagram showing the principle of the present invention.

As shown in FIG. 1, a primary side magnetic circuit has a plurality of magnetic poles each having a plurality of rectangular teeth arranged at equal pitch intervals, and has a permanent magnet and an excitation coil that provide magnetic flux to each of the magnetic poles. 1, a movable part consisting of a frame 2 that supports the primary magnetic circuit 1 movably on the secondary magnetic circuit 3 on the stationary side, and a plurality of rectangular teeth arranged at equal pitches equal to the above-mentioned pitch. In the linear pulse motor consisting of the secondary magnetic circuits 3 on the fixed side arranged in the frame 2, the linear pulse motor has a linear pulse motor having a linear pulse width of 2τ/n on a plane in the traveling direction centered at the center of the primary magnetic circuit l. -m (where τ is the pitch of the teeth, m is the number of phases of the motor, and n is the order of harmonics to be canceled with respect to the fundamental wave of the period of τ); Driving means 5 for swinging the side magnetic circuit l is provided.

[For production]

According to the present invention, when the movable part does not need to move at high speed, but when it reaches an area where it must be precisely and smoothly positioned, the driving means 5 moves the primary magnetic circuit l to a plane parallel to the traveling direction. It is oscillated by 2τ/n·m at the top.

Then, the shape of the teeth of the secondary side magnetic circuit 3 becomes relatively skewed as shown in FIG. 5, and positioning can be performed accurately and smoothly.

In other words, although it does not have to be at high speed, if the area needs to be precisely and smoothly positioned, the drive means 5 may simply be used.
If you oscillate the primary magnetic circuit l, you can achieve smooth positioning, so it doesn't have to be high speed, but it is easy to move the area that needs to be accurately and smoothly positioned. can be changed, increasing the degree of freedom.

Of course, the driving method should be at high speed (although this is fine, in areas where accurate and smooth positioning is required,
Micro-step driving may be used, and full-step driving may be used in areas requiring high speed.

〔Example〕

FIG. 2 is a block diagram of an LPM according to an embodiment of the present invention, in which an electromagnet is used as a driving means to swing the LPM.

The difference between FIG. 2 and the conventional example shown in FIG. 4 is that a thrust bearing 4 that supports the primary magnetic circuit l is attached to an aluminum frame 2, and In addition, the electromagnet 5-1 is attached to the frame 2, and the return spring 5-2 is connected to the frame 2 and the primary side. This is the point attached between the magnetic circuits 1.

In this case, the primary magnetic circuit 1 is always connected to the secondary magnetic circuit 2 across the gap due to the magnetic attraction force of the permanent magnets 13 and 14.
The thrust bearing 4 receives the suction force and becomes swingable as described above.

Therefore, normally, a current is applied to the electromagnet 5 to attract the primary magnetic circuit 1 and to make it parallel to the secondary magnetic circuit 3.

When the movable part moves and reaches an area where it must be moved at high speed (or better yet, accurately and smoothly), if the current of the electromagnet 5 is cut off, the primary side The magnetic circuit 1 is inclined by τ/4 with respect to the secondary magnetic circuit 3, and is equivalent to the skewed case shown in FIG.

FIG. 3 is a block diagram of a PM according to another embodiment of the present invention,
As the drive means, a piezoelectric element is used for swinging, and (B) shows the displacement magnification mechanism.

The difference between FIG. 3 and FIG. 2 is that a displacement magnifying mechanism 5-3 using a piezoelectric element 5-4 is used instead of the electromagnet 5-1, so the explanation will focus on the different points.

When a voltage is applied to the piezoelectric element 5-4 shown in FIGS. 3A and 3B, the element extends and the primary magnetic circuit 1 becomes parallel to the secondary magnetic circuit 3.

When no voltage is applied, the primary magnetic circuit 1 is inclined by τ/4 with respect to the secondary magnetic circuit 3 due to the return spring 5-2.

Since the displacement of the piezoelectric element 5-4 is as small as several tens of μm, the displacement of the element is expanded by (z2#+)x(12a/13) using a two-stage lever mechanism as shown in FIG. 3(B). There is.

In this case, even when voltage is applied, almost no current flows through the piezoelectric element 5-4, and the power consumption is smaller than when an electromagnet is used.

Of course, as a driving method, high speed (or better), but accuracy (in areas where smooth positioning is required,
Micro-step driving may be used, and full-step driving may be used in areas requiring high speed.

〔Effect of the invention〕

As described in detail above, according to the present invention, there is an effect that a highly self-explanatory LPM can be obtained that can easily change the area that must be moved at high speed (or better yet, precisely and smoothly).

[Brief explanation of drawings]

Fig. 1 is a diagram of the principle of the present invention, Fig. 2 is a block diagram of a linear pulse motor according to an embodiment of the present invention, Fig. 3 is a block diagram of a linear pulse motor of another embodiment of the present invention, and Fig. 4 is a block diagram of a linear pulse motor according to another embodiment of the present invention. FIG. 5 is a diagram showing the configuration of a conventional linear pulse motor, FIG. 5 is a diagram showing an example of the tooth shape of the secondary magnetic circuit, and FIG. 6 is an explanatory diagram of an example of full-step drive. In the figure, 1 is a primary magnetic circuit, 2 is a frame, 3 is a secondary magnetic circuit, 4 is a support means, a thrust bearing, 5 is a drive means, 5-1 is an electromagnet, 5-2 is a return spring, 5-3 is a displacement magnifying mechanism, 5-4 is a piezoelectric element, 10 is a radial bearing for supporting the gap, ■ is a radial bearing for a linear guide, 2 is a yoke, 3 and I4 are permanent magnets, 5.16 is an excitation coil show. Plan view Front view Linear pulse of the ceiling example of the present invention
51.
qO structure diagram (/lf@t+l2iSmvJ) Diagram (A) Front view (8) (@ Front view The conventional linear pulse of Italy 1 is a bridge construction diagram No. 4 With cedar hakama and knee-high knee Secondary side magnetic circuit e Tooth shape V example 1 piece T diagram Figure 3 Mouth @Ganren phase j 1st side He Hungfeng coil 15) 11 rows of full throttle (I phase Wanfat 2nd mouth secondary flight 1 34 90° 27θ 2 Phase side (Manga Tanuki) I) 16) , Two-drive f Yingming Zusu 2-phase connection) Fig.

Claims (1)

[Scope of Claims] [1] A primary side having a plurality of magnetic poles each having a plurality of rectangular teeth arranged at equal pitch intervals, and having a permanent magnet and an excitation coil that provide magnetic flux to each of the magnetic poles. A magnetic circuit (1), and the primary side magnetic circuit (1) is connected to a fixed side secondary side magnetic circuit (3).
), and a fixed side secondary magnetic circuit (3) comprising a plurality of rectangular teeth arranged at equal pitch intervals equal to the above-mentioned pitch. In the linear pulse motor, the frame (2) is provided with 2τ/n m (where τ is the tooth pitch, m
The supporting means (4
), and a driving means (5) for swinging the primary side magnetic circuit (1). [2] A linear pulse motor characterized in that a thrust bearing is used as the support means (4) according to claim 1, and an electromagnet or a piezoelectric element is used as the drive means (5).