JPH01190251A - Linear motor - Google Patents

Abstract

PURPOSE:To obtain a movable element producing little noise by laminating conductors or said conductor and a ferromagnetic body and by interposing a viscoelastic resin between respective layers for constituting said movable element. CONSTITUTION:A secondary side movable element 2 is not an integral conductor but is divided into two layers of a movable element upper conductor 2a and lower conductor 2b to form a sandwich structure having a viscoelastic resin 5 between said two layers. Said conductor 2 is normally a 1-5 mm aluminum or copper material plate and the viscoelastic resin 5 is an acrylic high polymer material or the like and has a thickness of several ten mus- several hundred mus. Thus, because a large damping effect for changing vibrational energy into heat energy is given by the viscoelastic resin 5 when a resonance phenomenon occurs, it is possible to prevent the generation of such remarkable noise and vibration as those known heretofore even if the movable element 2 resonates.

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention] (Industrial Application Field) The present invention relates to a linear motor used as a drive source for conveyance equipment, etc.

(Prior Art) Linear motors have the characteristics of high acceleration and low deceleration, and are used as a drive source for conveyance systems. This linear motor consists of a part called a primary side which is a power feeding side and is an excitation side, and a secondary side which is a non-power feeding side.

The next side consists of an iron core and a winding, and the iron core is laminated with slots punched out, and windings are wound around the slots in multiple layers, and the windings have the same structure. , consisting of several coils spatially spaced at regular intervals. Depending on the shape of the linear motor, the secondary side may be made of a single non-magnetic conductor such as aluminum or copper, or a composite conductor combined with a ferromagnetic material. In such a configuration, when an alternating current is passed through the secondary winding, a magnetic flux is generated according to Lenz's right-handed screw law, and this magnetic flux causes an eddy current to flow on the surface of the secondary side, and the magnetic flux also flows through the winding. Due to the arrangement of the magnetic field, it becomes a traveling magnetic field that moves with time, so the wax current generates thrust due to changes in magnetic flux. There are usually two types of linear motors: one-sided type and two-sided type. The former has a single primary side, and the secondary side is a single conductor made of aluminum or copper plate, or is lined with a ferromagnetic material such as a steel plate. In some cases, a reaction plate is used, and the latter has a slot portion on the primary side facing a single conductor.

The conventional example shown in FIG. 7 is a structural conceptual diagram of a double-sided linear motor among these. The primary side, which is the power feeding side, is the stator, and the secondary side, which is the non-power feeding side, is the movable element. In the figure, 1a is an upper stator, 1b is a lower stator, and a plate-shaped movable element 2, which is a single conductor, connects the windings to the stator surface through a certain gap between both stators. It is provided so as to be movable in parallel to the wiring direction. Slots 3 are punched out in the upper stator 1 a s and the lower stator 1 b, in which windings 4 are arranged, spatially offset at regular intervals, wound at regular intervals. By supplying power to this winding, electromagnetic force is generated in the movable element 2, which is the secondary side, based on the operating principle of the linear motor, and the movable element 2 moves.

(Problem to be solved by the invention) Up until now, the primary side of a linear motor has been supplied with sine wave alternating current, but in response to the recent demand for a variable speed function to improve the efficiency of conveyance, an inverter power source has been used to There are many cases where electricity is supplied. In a linear motor, even when driven by a sine wave alternating current, various harmonic magnetic fluxes including a fundamental wave are generated. In addition, in the inverter drive, carrier components enter, and these act on the movable element 2 as electromagnetic excitation force. Since the movable element 2 is originally a flat plate with a simple shape, it has a high natural frequency and is not structurally attenuated by the electromagnetic excitation force, and when it resonates, it produces a significantly large noise. It had elements that occur. When a linear motor is driven by an inverter, the carrier frequency is changed for speed control, which often causes the carrier frequency to enter the resonance range of the movable element 2 and generate a harsh sound.

Therefore, the object of the present invention is to provide a linear motor that produces less noise even when over-speed driven by an inverter. In a linear motor, which is composed of a stator that generates a The feature is that the mover is constructed with a viscoelastic resin interposed therebetween.

(Function) As mentioned above, by interposing the viscoelastic layer between the conductor or conductor and ferromagnetic layers that make up the mover, the viscoelastic layer converts vibrational energy into thermal energy during resonance, resulting in significant vibration damping. Because of this effect, even if the movable element resonates, it is possible to prevent the occurrence of significant noise and vibration as in the conventional case.

(Example) An example will be described below with reference to FIG. FIG. 1 is a conceptual diagram of the structure of a double-sided linear motor showing an example of the present invention. The stator on the primary side, which is the power supply side, consists of an upper stator 1a and a lower stator 1b.
The mover 2 is positioned with a certain gap in between. Slots 3 are punched out in each of the upper stator 1a and the lower stator 1b, and windings 4 spaced apart from each other at regular intervals are wound therein and arranged at regular intervals.

The movable element 2 on the secondary side is not an integrated conductor, but has a sandwich structure in which the movable element is divided into two layers, an upper conductor 2a and a lower conductor 2b, with a viscoelastic resin 5 in between. Conductor 2 is usually 1
The viscoelastic resin 5 is made of an acrylic polymer material and has a thickness of several tens of microns to several hundreds of microns.

Next, the operation of the embodiment will be explained with reference to FIGS. 2 and 3.

The conductor 2 of the linear motor is susceptible to electromagnetic force waves in the longitudinal direction, and the shape of the conductor 2 of the mover 2 is generally a rectangular plate.
The natural frequency of bending in such a shape is, where: a: Length in the longitudinal direction υ: Length in the lateral direction of the Borian ratio b m: Number of nodes in the longitudinal direction t: Plate thickness
n: Indicates the number of nodes in the horizontal direction.

Figure 2 shows an example of the mode of such a natural frequency.
With a, 6b-m-3. A mode where n=1 is shown. For example, when an electromagnetic force wave that matches the natural frequency of this mode acts on a conductor, the conductor will amplify its vibrations, and if the modes of the electromagnetic force waves are also the same, extremely significant vibration will occur.

However, at the time of resonance, the mover upper conductor 2a and lower conductor 2
The viscoelastic resin inserted between the material and the material b acts as a damping force.

This damping force will be explained using FIG. 3.

FIG. 3 is an enlarged view of the main part of the movable element 2 during vibration deformation in the configuration of the present invention, and the structure of the movable element 2 is such that a viscoelastic resin 5 However, under this configuration, a deformation is shown in which the mover lower conductor 2b is placed inside. At this time, if the Young's modulus of the viscoelastic resin 5 is extremely low, and the upper conductor 2a and the lower conductor 2b have the same thickness and are made of the same material, they will have the same bending rigidity and the same curvature of deformation. As a result, the upper layer portion 21a of the mover upper conductor 2a extends with its center portion 22a as a boundary, and the lower layer portion 23a is compressed. 21b is expanded and the lower layer portion 23b is in a compressed state.

Due to such deformation, the ends of the lower skin part 203 of the lower layer part 23a of the upper conductor and the epithelial part 201 of the upper layer part 21b of the lower conductor
A deviation δ occurs at the end of the . When the conductor vibrates at a frequency f, this deviation δ is repeated f times per second. During this repeated displacement, the viscoelastic body 5 acts as a resistance force and changes vibrational energy into thermal energy.

As described above, the conductor 2 of the linear motor with the sandwich structure of the viscoelastic body 5 has high vibration absorption performance.

Next, the effects of the embodiment will be explained using FIG. 4. When an excitation force acts on a structure having a vibration damping force, not only the movable element 2 of a linear motor, the structure is represented by the following forced vibration magnification Mf.

Here, f: Vibration frequency fn: Natural frequency ζ: Damping coefficient Generally, in a conductive material such as that used for the conductor of the mover 2 without structural damping, ζ<10-3. When such a material resonates, it draws an enlarged curve as shown in FIG. 4 (a).

However, in the mover conductor 2 that includes the viscoelastic body 5, ζ
>10-' is obtained.

As a result, the vibration expansion curve shows a situation as shown in FIG. 4 (b).

By achieving the effect of significantly reducing vibration as described above, when driven by a linear motor, even when resonance occurs with electromagnetic force waves, regardless of whether it is a sine wave or an inverter, the vibration does not become so large that unpleasant resonance noise is generated. A quiet linear motor is provided.

In the embodiment described above, the case where the movable element 2 is a two-layer conductor is illustrated, but a vibration damping effect can be obtained even if the movable element 2 is a three-layer conductor. An example of this is shown in FIG.

In FIG. 5, the mover 2 is a three-layer sandwich in which a viscoelastic resin 5 is inserted between the mover upper conductor 2a and the mover middle conductor 2c, and between the mover middle conductor 2C and the mover lower conductor 2b. Show the structure.

Moreover, although the linear motor illustrated so far has been an example of a double-sided linear motor in which the stator 1 is disposed on both sides, a configuration in which the same effect can be obtained can be achieved with a single-sided linear motor. An example is shown in FIG.

Figure 6 shows that the side of the mover 2 facing the single-sided stator IC has a mover single-side conductor 2d, and on the back side there is a ferromagnetic material 7 made of iron or the like, with a viscoelastic resin sandwiched between them. It has a sandwich structure.

[Effects of the Invention] As described above, if the movable element of the linear motor is made of only a conductor, the structure is such that the movable element has two or more layers and the viscoelastic resin 5 is inserted between them, and the movable element is layered with a conductive layer and a ferromagnetic layer. By using a structure in which a viscoelastic resin is sandwiched between the layers, even if various electromagnetic force waves act on the mover, resonance vibrations are absorbed by the displacement of the viscoelastic layer due to the deformation of the mover. Therefore, the vibration does not increase much, and unpleasant resonance noise can be prevented.

[Brief explanation of the drawing]

FIG. 1 is a conceptual diagram of the structure of a double-sided linear motor showing an embodiment of the present invention, FIG. 2 is a diagram showing an example of the vibration mode in the mover of the linear motor of the present invention, and FIG. 3 is a diagram showing an example of the vibration mode of the linear motor of the present invention. Fig. 4 is an enlarged view of the main part explaining the deformation due to vibration of the movable element of the linear motor.
FIG. 6 is a conceptual diagram showing an embodiment of a single-sided linear motor, and FIG. 7 is a conceptual diagram of the structure of a conventional double-sided linear motor. 1... Upper stator, IC... Single side stator, 2...
...Mover, 3...Slot, 4...Winding, 5
... Viscoelastic resin, 6a, 6b... Vibration nodes. Agent Patent Attorney Nori Ken Yudo Chika Ken Maru 1st If Figure 2 Figure 31! l No. 41! a

Claims (2)

[Claims] (1) A linear motor consisting of a stator whose windings are housed in slots of a laminated core and which generates a traveling magnetic field, and a movable element which is made of a conductor and which moves in response to the traveling magnetic field. A linear motor characterized in that a viscoelastic resin is interposed between multiple layers. (2) Consisting of a stator that has windings housed in slots in a laminated core and generates a traveling magnetic field, and a mover that is made of laminated conductors and ferromagnetic materials that moves in response to the traveling magnetic field. A linear motor characterized in that a viscoelastic resin is interposed between the layers of the movable element.