RU2292960C2 - Electromechanical vibrator - Google Patents

Abstract

FIELD: building industry; electromechanical vibrators used in building.

SUBSTANCE: the invention is pertaining to the vibration engineering, in particular, to the electromechanical vibrators used in building for the concrete consolidation by vibration. The electromechanical vibrator uses as the misbalance the located in the vibrator stator internal reboring geared cylindrical core made out of the electric steel plates, which is fixed in the body by means of the resilient components with the capability of the circular motion inside the electromagnetic system of the stator. Such design allows to gain during the electromechanical vibrator operation the circular trajectory of movement of the mass center of the magnet keeper without its rotation around its own axis. The electromagnetic system of the stator is made with the one-sidedly-asymmetric rotating magnetic field. Physically it means substitution of rotation of the core mass center around its own axis for its translational movement on the curvilinear (circular) trajectory. At that instead of the contact friction of the rolling bodies in the bearing box use the deformations of the molecular bonds in the resilient component, for example made out of the elastomer, which are practically wear-free. The technical result of the invention is the increased reliability and the expanded range of the smooth adjustment of the frequency and amplitude of the vibrator oscillations.

EFFECT: the invention ensures the increased reliability and the expanded range of the smooth adjustment of the frequency and amplitude of the vibrator oscillations.

4 cl, 5 dwg

Description

The invention relates to vibration technology, namely, electromechanical vibrators used, for example, in construction for vibration compaction of concrete and other branches of technology where vibration exposure to the material being processed is required.

Widely known are traditional electromechanical vibrators, including those produced by the Yaroslavl factory Red Lighthouse. They consist of an induction motor, on the extensions of the rotor shaft of which there are unbalances. When the rotor rotates, these unbalances create a driving force of oscillations, which are transmitted through the body and mounting legs to the working body, for example, a vibrating platform, which interacts with the concrete mixture being compacted. The design of such an electromechanical vibrator is visible in Fig. 33, p. 100 (K.K. Gogia. Formation of reinforced concrete products. M: Stroyizdat, 1989).

This vibrator design is taken as a prototype.

The vibrator consists of an electric motor (stator, inside of which a rotor is located on the shaft) in the housing. The motor shaft is equipped with unbalances and rotates in ball bearings located in the bearing housings of the housing.

The disadvantage of all known vibrators, including the prototype, is the presence of a rotor rotating in the bearings, since with increasing vibration frequency (rotor speed), the centrifugal driving force proportional to the square of the frequency increases, but the load on the bearings also increases, their durability decreases, and, thus, the reliability of the vibrator is reduced.

The lack of technically acceptable solutions for variable speed-independent smooth control of the oscillation amplitude in electromechanical vibrators limits their technological application.

The task of the invention is to increase reliability and expand the range of smooth regulation of the frequency and amplitude of vibrations of the vibrator.

This problem is solved in that a toothed cylindrical core made of electrical steel plates (hereinafter referred to as the core) is mounted in the housing by means of elastic elements with the possibility of circular movements inside the electromagnetic system of the stator as an unbalance in the internal bore of the vibrator stator. This design allows you to get during the operation of the vibrator a circular path of the center of mass of the armature without its rotation around its own axis.

The electromagnetic system of the stator is made with a one-way asymmetric rotating magnetic field. Physically, this means replacing the rotation of the center of mass of the core (unbalance) around its own axis with its translational movement along a curved (circular) path, while instead of contact friction of the rolling elements in the bearing, molecular bonds in an elastic element, for example from an elastomer, are practically unbearable.

To obtain a one-sided asymmetric rotating magnetic field, for example, a three-phase electromagnetic system can be used, which contains in each phase two serially connected pole-forming coils with a shortened pitch (y≈0.5τ), each of the coils is shunted by a diode, with diodes shunting coils of one phase are turned on counter.

The electric drive of the inventive vibrator is, in essence, a transformed version of a synchronous-reactive electric machine with Z ₁ = Z ₂ , which, as is known from the theory of electric machines, cannot develop a starting torque, which, together with the reaction of elastic supports, reliably prevents the core from rolling relative to stator in the process.

The elastic elements can be made of elastomer for low power vibrators or in the form of torsion bars for high power vibrators.

The essential features common with the prototype are: the housing in which the stator is located, the shaft mounted in the vibrator housing, on which the unbalance is located.

Figure 1 shows a longitudinal section of the proposed vibrator, figure 2 is a diagram of the placement of coils in the grooves of the stator, figure 3 is a sequence of phases of movement of the core in the bore of the stator, figure 4 is a diagram of the connections of the coils and shunt diodes, fig. 5 - movement of a wave of magnetizing force F along the grooves of the stator.

The vibrator contains a housing 1, in which a stator 2 with a winding 3 is located, which, as mentioned above, can be made, for example, in the form of a three-phase electromagnetic system, which contains in each phase two serially connected pole-forming coils with a shortened pitch (y≈0 5τ), each of the coils is shunted by a diode, and the diodes shunting the coils of one phase are turned on in the opposite direction (Fig. 4). Inside the stator there is a toothed cylindrical core (unbalance) 4 on the shaft 5. The shaft 5 at its ends has thrust bearings 6 for elastic elements 7 of elastomer, for example plate-shaped ones, which are fixed in the covers 8 of the housing 1. Between the inner cylindrical surface of the stator 2 and the outer gear surface core 4 there is an air gap 9, which compared with conventional electric machines is significantly increased to ensure translational movement of the core in a circular path. For high-power vibrators, elastic elements can be made in the form of torsions (not shown conditionally in Fig. 1).

The vibrator works as follows.

When the stator windings are fed with a three-phase current, the core 4, under the influence of the electromagnetic force of one-sided attraction, successively occupies eccentric positions inside the stator bore 2 at each moment of time, depending on which stator winding at this moment of time creates the electromagnetic force of attraction of the teeth of the core. Thus, the core 4 performs a plane-parallel instantly translational (rotational) movement, while for one cycle of alternating current the trajectory of the center of mass of the core 4 describes a complete circle.

As an example of execution, figure 2 shows a diagram of the electromagnetic system of the proposed vibrator with the following parameters:

- the number of phases of the stator winding m = 3;

- the number of poles of the stator winding 2p = 2;

- the number of grooves and, accordingly, the teeth on the stator Z ₁ = 12;

- the number of teeth on the anchor Z ₂ = 12;

- the stator winding is single-layer, concentrated;

- the number of coils in phase 2;

- coil pitch y≈0.5τ;

- marking coils in phases:

phase A, A1-X1 and A2-X2

phase B, B1-U1 and B2-U2

phase C, C1-Z1 and C2-Z2;

- the air gap 5 in comparison with conventional electric machines is significantly increased, reaching δ = (3-3.5) A, where A is the amplitude of core oscillations, for example, at A≈1.5 mm, δ = 5 mm.

The coils are connected in series and in accordance, each of the coils is shunted by a diode, which in the phase have a counter inclusion.

When the windings are fed with a three-phase current with a circular frequency ω = 2πf rad / s, where f is the current frequency Hz, the instantaneous values of the currents in phases:

- i _A = I _m sinωt, A;

- i _B = I _m · sin (ωt-120 °), A;

- i _С = I _m · sin (ωt + 120 °), A.

Under the action of a single-acting electromagnetic force arising under the influence of waves of the magnetizing force of the stator, and depending on the phase of the current i, the core inside the stator bore occupies the positions illustrated in FIG. 3. For clarity, reference marks • R and • r are applied to one of the stator teeth and the opposite tooth of the core. As can be seen in figure 3, the core of the proposed vibrator performs plane-parallel instantaneous translational motion along a circular path. Here, O _{1 is the} axis of symmetry of the stator, O ₂ is the axis of symmetry of the core.

You can approximately estimate the magnitude of the electromagnetic force F _em in a submersible vibrator made according to the above parameters, with dimensions:

- the diameter of the stator bore - D _c = 40 mm;

- the length of the stator and anchor packets - l _c = l _i = 150 mm;

- average induction in the gap In _equiv = 0.7 T

F _em = B _equiv ² / 2μ ₀ · S _f ≈ 0.4 · 10 ⁶ · V _equiv ² · S _f = 0.4 · 10 ⁶ · 0.7 ² · 40 · 150 · 10 ^-3 ≈1180 N, Where

- S _f - the cross section of the magnetic flux in the air gap, m ² ;

- μ ₀ - magnetic permeability of the vacuum, μ ₀ = 1,256 · 10 ^-6 GN / m

Under the influence of F _{em, the} elastic elements 7 are deformed, and the center of mass of the core begins to move along a circular path of radius r, creating a centrifugal force F _cb

F _cb = m _c · r · ω ² , where

m _c is the mass of the core,

ω = 2πf - circular frequency

For example, if m _c = 1 kg, r = 4 mm, f = 200 Hz,

then F _cb = 1 · 4 · 10 ^-3 · (2 · 3,14 · 200) ² ≈6320 N.

.Force is transmitted through the elastic elements to the stator

.

Thus, the magnitude of the driving force of the inventive vibrator is not inferior to traditional vibrators with rotating unbalances.

It is significant that the value of F _em does not depend on the frequency f, that is, when the frequency changes, the magnitude of the electromagnetic force does not change.

The most effective operation of the inventive vibrator in conjunction with a semiconductor frequency converter, then the amplitude of the oscillations A can be controlled by the output voltage of the converter, and the vibration frequency by the current frequency.

Modern materials, the production technology of electric machines allow the production of the proposed vibrators at electric machine-building enterprises, in particular, at the applicant plant, experimental design work is currently underway on this vibrator.

Claims (4)

1. Electromechanical vibrator comprising a housing with a stator, an imbalance, the shaft of which is fixed in the housing, characterized in that the imbalance is made in the form of a toothed cylindrical core of plates of electrical steel, the shaft of which is fixed in the housing by means of elastic elements that allow the core to make circular movements inside the electromagnetic a stator system made with a one-way asymmetric rotating magnetic field. 2. The electromechanical vibrator according to claim 1, characterized in that the stator electromagnetic system is three-phase and contains in each phase two serially connected pole-forming coils, each of which is shunted by a diode, and the diodes in the phase are turned on counter-clockwise. 3. The electromechanical vibrator according to claim 1, characterized in that the elastic elements are made of elastomer. 4. The electromechanical vibrator according to claim 1, characterized in that the elastic elements are made in the form of torsions.

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