JPH0312041Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a vibrating motor used for compacting concrete for construction and civil engineering.

[Conventional technology]

At construction sites for concrete structures, in order to ensure that the poured concrete reaches every nook and cranny, pipes reinforcing the formwork are
A vibrating electric motor with a rotation speed of 6,000 rpm (50 Hz area) and 7,200 rpm (60 Hz area) is strongly fixed, and vibrates the concrete through this pipe.

FIG. 7 is a partially cutaway side view showing the configuration of a general vibration electric motor, in which 41 is a stator, 42 is a rotor, 43 is a winding coil, 44 is a rotating shaft, 45 is a bearing, and 46 is an unbalanced weight. , 47 is a frame,
48 is a bracket. When this vibration motor is energized, current flows through the winding coil 43 and the rotor 4
2 rotates. Since the rotating shaft 44 is press-fitted into the rotor 42, it rotates together with the rotor 42.

The rotating shaft 44 is supported at both ends by bearings 45, allowing smooth rotation. An unbalanced weight 46 is fixed inside the bearing 45, and the rotating shaft 4
It rotates as one with 4.

Here, if the weight of the combined unbalanced weight 46 of the two unbalanced weights 46 is W [Kgf], and the distance from the center of the rotating shaft 44 to the center of gravity of the unbalanced weight 46 is r, then the angular velocity is The centrifugal force F when rotating at ω [radian/sec] is F=Wrω ² /g [Kgf] (where g is gravitational acceleration = 980 cm/sec ² ). This is the vibration force generation principle of a general vibration electric motor, and is the 8th principle.
As shown in the figure, centrifugal force F is generated on a line connecting the center of the rotating shaft and the center of gravity of the unbalanced weight.

FIG. 4 (a is a plan view, b is a side view, and c is a front view) shows a vibrating motor 1 fixed by a clamp fitting 2 firmly fixed to a reinforcing pipe 11, a screw 3, a lever handle 5, and a holding plate 6. This shows the state in which the

In addition, in FIG. 4, 13 and 14 are concrete formwork, 15 is a spacer bolt, and 16 is a nut.

In Figure 4a, F ₁ is an effective force that vibrates the pipe, but F ₂ is an ineffective force, and
It resonates at a low resonant frequency (3000-4500 rpm) in this direction and consumes a lot of input, and the rotation does not increase.
This causes the inconvenience that the specified rotational speed is not achieved and the vibration force is also small.

This resonance in the _y2 direction is caused by the deformation in the y direction of the reinforcing pipe 12, which is reinforced by being inserted at right angles to the reinforcing pipe 11.

On the other hand, when _F1 acts on the line connecting the center of the reinforcing pipe 11 and the center of the vibration motor 1 as shown in FIG. 4a, the vibration motor shown in FIG. 7 moves in this direction without rotational motion. Force is transmitted, but if the force is in a phase other than this, a force that twists the reinforcing pipe 11 acts, and is maximum at _F2 , which is perpendicular to _F1 .

The torsional resonance point of the reinforcing pipe 11 is also between a relatively low rotational speed (3000 to 4500 rpm), and resonance occurs at this point, causing large vibration in the _F2 direction. In this case, _F2 is consumed to accelerate the mass of the vibrating body around the center of the reinforcing pipe 11, and the remaining amount gives vibration to the reinforcing pipe 11, so the effect is small.

In this way, with the conventional mounting method of a vibrating motor, there are many resonance frequencies below 6000 rpm due to the structure, so if one of them resonates, the vibration motor will not be able to increase its rotation speed any further (for example,
(rotating at 3500 rpm), the vibration force was weak, and due to the characteristics of the electric motor, a large amount of current and input was required at intermediate rotation speeds.

In order to solve these problems, the applicant of the present application previously proposed a method of mounting a vibration motor provided with a steady rest as shown in FIG. 4.

That is, the vibration motor 1 is fixed to the vibration surface by a fixing plate made of a leaf spring 4 perpendicular to the vibration surface, with the rotating shaft located in a plane substantially parallel to the vibration surface, and the vibration motor 1 is rotated. A protrusion 7 is provided on the casing, and steady rests 8, 8 are provided to sandwich the protrusion 7 from both sides.

By adopting this installation method, the
It can easily pass through a resonance frequency lower than the resonance frequency of 4500 rpm and rotate at a set rotation speed of 6000 (or 7200) rpm.

[Problem that the invention attempts to solve]

When the vibration motor is provided with a steady rest means in this way, when the vibration motor passes the resonance point during acceleration, the protrusion 7 of the vibration motor hits the steady rests 8, 8 that suppress lateral vibration. At this time, if the torque produced by the vibrating motor cannot overcome the work equivalent to the regulating force that acts as a reaction force on the protrusion 7 when it hits the steady rests 8, 8, the motor will exceed this rotation speed. Unable to do so, this situation will continue. To solve this problem, an electric motor with a large capacity that can generate more torque than is necessary to generate the excitation force is required.

The present invention aims to solve these problems and provide a vibration motor that can pass through the resonance point without having more torque than necessary.

[Means for solving problems]

In order to achieve this purpose, the vibration electric motor of the present invention has an unbalanced weight 26 on the rotating shaft 24 of the motor, the center of gravity of which is eccentric to the rotation center of the rotating shaft 24.
In a vibration electric motor that generates vibration by attaching the unbalanced weight 26, the unbalanced weight 26 is attached to a sliding guide 31 fixed to the rotating shaft 24 by a movable weight 32 that is movable in the direction of increasing or decreasing the eccentricity. The movable weight 32 has a spring 33 that applies an elastic force in a direction in which the amount of eccentricity of the movable weight 32 becomes smaller.
Resonant rotation speed when attached to the vibrated object via
It is characterized in that it is set larger than the centrifugal force acting on the movable weight 32 at N ₀ and smaller than the centrifugal force acting on the movable weight 32 at a steady rotation speed.

[Effect]

In the present invention, when the rotation speed is low, the distance from the center of the rotating shaft to the center of gravity of the movable weight is short due to the spring, so the eccentric moment, which is the product of that distance and the mass of the movable weight, is small. Therefore, the amplitude at the resonance point can be reduced, and the resonance point can be easily passed through with a small torque. When the rotation speed approaches the set rotation speed, the centrifugal force overcomes the biasing force of the spring, so the center of gravity of the movable weight extends to the set position, and the eccentric moment increases. Therefore, a predetermined vibration force can be obtained at the rated rotation speed.

〔Example〕

Hereinafter, the present invention will be specifically explained based on embodiments shown in the drawings.

FIG. 1 is a partially cutaway side view of a vibration motor showing an embodiment of the present invention. In the figure, 21 is the stator, 22
is a rotor, 23 is a coil, 24 is a rotating shaft, 25 is a bearing, 26 is an unbalanced weight, 27 is a frame, and 28 is a bracket.

When this vibration motor 1 is energized, current flows through the coil 23 and the rotor 22 rotates. Rotating shaft 24
is press-fitted into the rotor 22, so the rotor 22
It rotates as one. Both ends of the rotating shaft 24 are supported by bearings 25 and rotate smoothly. An unbalanced weight 26 is fixed inside the bearing 25 and rotates together with the rotating shaft 24.

Let W [Kgf] be the weight of the combined unbalanced mass 26 of the two unbalanced masses 26, and let r be the distance from the center of the rotating shaft 24 to the center of gravity of the unbalanced mass 26, then the angular velocity ω [radian /sec], the centrifugal force F is F = Wrω ² /g [Kgf] (where g is the acceleration of gravity), and it is generated on the line connecting the center of the rotation axis and the center of gravity of the unbalanced weight. .

An example of the structure of the unbalanced weight 26 is shown in FIGS. 2 and 3. 31 is a sliding guide, 32 is a movable weight, 33
is a coil spring. The sliding guide 31 is connected to the rotating shaft 2
4 and engages with the movable weight 32 and coil spring 33.

The centrifugal force F′ generated on the movable weight 32 when the vibration electric motor 1 rotates at an angular velocity ω is
If the weight of is W ₁ [Kgf] and the distance from the center of the rotating shaft 24 to the center of gravity is r ₁ , then F′=W ₁ r ₁ ω ² /g [Kg
f] acts in the direction of the arrow in FIG. When the rotation increases and the centrifugal force F' becomes larger than the force T of the coil spring 33, the movable weight 32 overcomes the force T of the coil spring 33 and moves in the direction of the arrow, r ₁ also increases, and the centrifugal force F' increases, moves until the stroke S becomes zero, and stabilizes in the state shown in Figure 3. The distance from the center of the rotating shaft 24 to the center of gravity at this time is defined as _r2 .

In Fig. 4a, the weight of the vibration electric motor 1 is W ₀
[Kgf], and the spring constant of the leaf spring 4 is K[Kgf/
cm], the resonance rotational speed N ₀ is N ₀ = (60/2π) √ ₀ [rpm], and the amplitude a is a = Wrgω ² /g/
√( ₋₀ ² ) ² + (0.2× ₀ ² ) ² .

FIG. 5 shows an example of the characteristics of the unbalanced weight 26. As in this example, after passing the resonance rotation speed N ₀ , the eccentric moment becomes 2W ₁ r ₂ [Kgfcm] from 2W ₁ r ₁ [Kgfcm].
fcm].

Next, W ₀ = 3.9Kgf, K = 55Kgf/cm, 2W ₁ r ₁
= 0.054Kgf, 2W ₁ r ₂ = 0.374Kgfcm, then N ₀
=1123rpm.

FIG. 6 shows an example of calculation of the relationship between rotation speed and amplitude. The control width is determined by the allowable deformation amount determined by the allowable stress of the leaf spring 4 in the gap between the protrusion 7 and the steady rest 8 in FIG. The limit width in this example is 3 mm.
In the case of the conventional structure, the protrusion 7 hits the steady rest 8 at the rotation speed at point b during acceleration, as shown by the broken line in FIG. If the torque of the vibration motor 1 cannot overcome the work at this time, no further acceleration will be possible.
It continues to rotate at point b and cannot reach the desired rotation speed. In the case of the present invention, the protrusion 7 reaches the desired rotation speed without contacting the steady rest 8, as shown by the solid line.

Next, when the power is turned off, the rotation speed decreases while vibrating as shown by the solid line in Figure 6, but at the resonance point, unlike the solid line, it vibrates greatly, and the protrusion 7 hits the steady rest 8, consuming energy and stopping. leading to.

[Effect of idea]

As mentioned above, in the present invention, a movable unbalanced weight is used to reduce the eccentric moment until the rotation speed is low when passing the resonance point, and to reduce the eccentric moment to a predetermined value after passing the resonance point. has been established. Therefore, the vibration amplitude when the vibrating electric motor passes the resonance point during acceleration is small and is limited to the range of the gap between the steady rest and the protrusion of the electric motor. When the rotational speed exceeds that number, the unbalanced weight slides in the normal direction, the distance from the rotating shaft increases, and vibrations occur at a predetermined torque. Therefore, there is no need to use a large-capacity electric motor with a large rated torque just to exceed the resonance point, and a small, lightweight, and inexpensive electric motor can be used.

[Brief explanation of the drawing]

Fig. 1 is a partially cutaway sectional view showing an embodiment of the invention, Figs. 2 and 3 are explanatory diagrams of the action of the movable weight of the invention, and Fig. 4 is an installed state of the vibration motor of the invention. Figure 5 is a graph showing the relationship between rotational speed and eccentric moment of the present invention, Figure 6 is a graph showing the relationship between rotational speed and amplitude of the present invention together with the conventional case, and Figure 7 is the graph of the conventional case. FIG. 8, a partially cutaway side view showing the structure of the vibration motor, is an explanatory diagram of how vibration force appears. 1: Vibration electric motor, 2: Clamp fitting, 3: Screw, 4: Leaf spring, 5: Lever handle, 6: Holder plate, 7: Projection, 8: Steady rest, 11, 12:
Reinforcement pipe, 13, 14: Concrete formwork, 1
5: Spacer bolt, 16: Nut, 21: Stator, 22: Rotor, 23: Coil, 24: Rotating shaft, 25: Bearing, 26: Unbalanced weight, 2
7: Frame, 28: Bracket, 31: Sliding guide, 32: Movable weight, 33: Spring.

Claims (1)

[Claims for Utility Model Registration] In a vibrating electric motor that generates vibration by attaching an unbalanced weight 26 having a center of gravity at a position eccentric to the rotation center of the rotational shaft 24 to a rotating shaft 24 of the electric motor, The weight 26 is constituted by a movable weight 32 attached to a sliding guide 31 fixed to the rotating shaft 24 so as to be movable in a direction in which the amount of eccentricity increases or decreases, and the amount of eccentricity of the movable weight 32 is small. The vibrating motor is provided with a spring 33 that provides an elastic force in the direction of
Resonant rotation speed when attached to the vibrated object via
A vibrating electric motor characterized in that the centrifugal force acting on the movable weight 32 at N ₀ is set larger than the centrifugal force acting on the movable weight 32 and smaller than the centrifugal force at a steady rotation speed.