JP3235027B2 - Concrete vibrator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a concrete vibrator for compacting concrete by applying vibration to freshly poured concrete to cause air bubbles in the concrete to float, thereby eliminating voids.

[0002]

2. Description of the Related Art When vibration is applied to freshly poured concrete, air bubbles in the concrete float up, voids disappear, and components are separated due to a difference in specific gravity. The compaction strength of concrete is closely related to the defoaming amount and the component separation amount. If the defoaming is large, the concrete strength increases, but at the same time, the component separation starts, and if the component separation increases, the concrete strength decreases even though the defoaming is sufficiently performed. Thus, if vibration is applied to concrete, defoaming and component separation proceed simultaneously, and if the vibration is applied for too long, the compaction strength cannot be increased due to defoaming, and the effect of reduction in concrete strength due to component separation Therefore, it is required when concrete is poured that effective defoaming is performed while minimizing the time for applying vibration to a necessary minimum, and that an increase in component separation is avoided. Conventional concrete vibrators include Japanese Utility Model 60-150261.
There is a number. Japanese Utility Model Publication No. 60-150261 allows the start of time to be determined automatically. The compaction time is set according to the mixing conditions of concrete, gravel, etc., and the time is controlled appropriately to compact. Things.

[0003]

[Problems to be solved by the invention]
No. 60-150261, 1) It is troublesome to set the compaction time corresponding to the mixing conditions of concrete, gravel, etc., and setting the compaction time requires experience and anyone can set the time appropriately 2) If the setting time is not appropriate and the setting time is short, degassing is not sufficient, and if the setting time is long, component separation progresses greatly, so degassing is sufficient and compaction is possible. 3) When the compaction time elapses, the motor stops driving.It can be seen, however, when the mixing conditions of concrete, gravel, etc. change, change the compaction time each time and re-drive the motor. There is trouble.

[0004] From these, the following items have been raised as development themes. There is no need to input and set the slump value according to the type of concrete, and there is no need to input and set the vibration time even if the compaction time changes due to the change in the amount of casting. Determining when to start casting and when to end compaction without any input setting such as vibration time. As the compaction time until the defoaming ends for a while and the component separation progresses greatly, it is shorter than the casting time,
The motor speed must be set so that defoaming can be performed, and defoaming can be performed promptly regardless of the type of concrete and the amount of casting. After the compaction time until the defoaming is completed for the time being, the vibration must be suppressed without stopping and the progress of component separation can be avoided. Be able to determine the start and end of compaction. When the concrete is cast, the vibration returns greatly and the next work can be performed.

The inventors of the present application considered the relationship between the amount of air bubbles and the amount of separation and time, and the relationship between the amount of work and the voltage value and time, and obtained a graph shown in FIG. Fig. 5 (a),
(b) shows the motor of the concrete vibrator at 12,000r.
5 (c) and 5 (d) show the case where the motor of the concrete vibrator was rotated at 6,000 rpm. In FIG. 5, the amount of air bubbles is the residual air bubbles per unit volume of concrete, and the amount of segregation is a value obtained after casting from a dispersed state in which gravel, sand, and cement are uniformly kneaded by a mixer. The degree to which the specific gravity differs due to the vibration of the concrete vibrator is divided into each component.The work is not equal to the vibration energy of the motor but the amount of the vibration energy that contributes to compaction, and the voltage value is the concrete value. A voltage value corresponding to the motor current of the vibrator. The calculation formula of the vibration energy is shown by the following formula. Vibration energy = (angular velocity of eccentric pendulum) ² x (weight of eccentric pendulum) x (displacement from rotation center of eccentric pendulum to center of gravity) (gravitational acceleration) Figs. 5 (a) and 5 (b) And the following findings were obtained.
At 12,000 rpm, the amount of air bubbles and the amount of work each show a substantially hyperbolic change and decrease to near 0% in a short time. The voltage value also shows a substantially hyperbolic change in a short period of time substantially corresponding to the amount of air bubbles and the amount of work, and decreases and stabilizes to a constant value. Fig. 5 (c) and Fig. 5
Considering (d), the following findings were obtained. The bubble volume at 6,000 rpm slowly decreases over more than twice the time, and a considerable amount remains even after a long time. The work value and the voltage value each have a small initial value, change in a curve with a gentle slope for a long time, and decrease to nearly 0%. Considering FIG. 5 (a) and FIG. 5 (c), the following findings were obtained. In each case, the amount of separation is substantially proportional to time. The gradient coefficient of the line is approximately proportional to the magnitude of the vibration energy,
The gradient coefficient in FIG. 5A and the gradient coefficient in FIG. 5C have a ratio of about 3: 1. In FIG. 5A, when the concrete vibrator is driven and a time e elapses, a line a indicating the amount of bubbles and a line b indicating the amount of separation intersect at a point c. The amount of separation d at point c does not adversely affect the compaction strength. To remove the bubble amount d at the point c, the concrete vibrator must be driven until the time f has elapsed. Even if the concrete vibrator is driven until the time f elapses and the bubble amount is set to 0%, the separation amount g at this time is about twice as large as the separation amount d at the point c to reduce the compaction strength. Become. Therefore, it is necessary to avoid an increase in the amount of separation after the time e has elapsed by driving the concrete vibrator. In the case of the casting work at 12,000 revolutions, if the driving is stopped after the time e has elapsed after driving the concrete vibrator, the motor must be restarted at the time of the casting.
When concrete is poured, driving the concrete vibrator at 6,000 rpm will take too much time and will result in incomplete defoaming even if compaction is completed for a long time. Considering FIGS. 5 (b) and 5 (d), the following findings were obtained. While the voltage value at 12,000 rpm shows a substantially hyperbolic change substantially corresponding to the bubble amount, the bubble amount, work amount and voltage value at 6,000 rpm do not decrease in a short time, and the voltage value is No change curve corresponding to the amount of bubbles is shown.

The present invention solves the disadvantages of the prior art based on the above findings. In various construction works for casting concrete, when the concrete is started to be cast, the rotation speed is automatically increased to a high value. High-vibration energy to quickly degas the concrete, and when the defoaming is accelerated and a satisfactory compacting strength is obtained, the number of revolutions is automatically reduced to reduce the degassing of the concrete. An object of the present invention is to provide a concrete vibrator which can be continued slowly, can suppress the promotion of separation of concrete components, and can judge when concrete is charged.

[0007]

According to a first aspect of the present invention, there is provided a concrete vibrator using a motor capable of changing a motor rotation speed based on a speed command signal output from a speed command control circuit as a vibration generating source, The speed command control circuit detects a voltage proportional to the motor current and compares it with a single threshold voltage that is set in advance. When the detected voltage becomes larger due to concrete input, vibration increases. In this way, the motor is rotated at a high speed so that the required frequency is such that deaeration can be completed in a short compaction time, and when the compaction time elapses and the detected voltage becomes smaller, the progress of component separation becomes slow. It is an object of the present invention to provide a concrete vibrator characterized in that the motor is rotated at a low speed so as to have a required frequency.

[0008] The second invention of the present application is a concrete vibrator using a motor capable of varying the motor rotation speed based on a speed command signal output from a speed command control circuit as a vibration source, in order to solve the above-mentioned problems. The speed command control circuit detects a voltage proportional to the motor current and compares the detected voltage with one of two threshold voltages, large and small. When concrete is charged, the detected voltage becomes larger than the threshold voltage (small). At times, the motor is rotated at a high speed so that the required frequency can be completed in a short compaction time due to an increase in vibration, and the threshold voltage (small) is switched to the threshold voltage (large). When the detected voltage becomes smaller than the threshold voltage (large) after elapse of the time, the motor is rotated at a low speed so that the required frequency at which the progress of the component separation is slowed down, and the threshold is Pressure threshold voltage from Large Small
The present invention provides a concrete vibrator characterized by having a configuration for switching to a concrete vibrator.

According to the present invention, in various construction works for casting concrete, when the concrete is started to be poured, the number of revolutions is automatically increased to apply high vibration energy to the concrete so that the concrete can be quickly defoamed. On the other hand, when the defoaming is accelerated and a satisfactory compacting strength is obtained, the number of revolutions is automatically reduced, the defoaming of the concrete is gently continued, and the promotion of the separation of the concrete component can be suppressed.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A first embodiment of a concrete vibrator according to the present invention will be described with reference to FIGS.
This embodiment shows one using a sensorless brushless motor. As shown in FIG. 1, the motor control circuit includes a permanent magnet rotor 1, three stator windings 21,
2 and 23 are Y-connected three-phase stator windings 2 and a transistor group U which is supplied with power from a DC power supply 8 and receives a commutation control signal.
+, V +, W +, U-, V-, and W- are controlled to be on / off as required to output an AC voltage to the output lines 31, 32, and 33 to control the commutation of the three-phase stator winding 2. Three-phase inverter 3
And the three resistance wires 51, 52, 53 are Y-connected, and the non-neutral point terminals of the resistance wires 51, 52, 53 are connected to the three stator windings 21 of the three-phase stator winding 2. , 22 and 23 connected to the corresponding non-neutral point side terminals, the potential e ₂ of the neutral point of the three-phase resistor circuit 5a and the three-phase stator winding 2 The potential e _{1 at the} neutral point is input to the differential amplifier 5b to detect an induced voltage of each stator winding of the three-phase stator winding 2 and to obtain 3 × n times the fundamental wave included in the induced voltage. A required rotational position signal e corresponding to only a triple harmonic of the fundamental wave corresponding to the predetermined rotational position of the permanent magnet rotor 1 from among the harmonics
₃ , a rotation position detection circuit 5 for outputting a rotation position signal e ₃
And a microcomputer 6 that outputs an inverter drive reference signal m and a rotation speed corresponding signal e ₄ to the commutation control circuit 4, and inputs an inverter drive reference signal m and a rotation speed corresponding signal e ₄ to perform pulse width modulation. a commutation control circuit 4 for outputting a commutation control signal e ₆ to perform three-phase inverter 3, the speed command to the high rotation of the motor based on the magnitude of the motor current signal e _5H and the speed command signal e to switch to low rotation _The speed command control circuit 7 outputs _5L to the commutation control circuit 4.

The commutation control circuit 4 includes a comparator 41, a pulse width modulator (PWM) 42, and a limiter circuit 43.

The comparator 41 receives the speed command signals e _{5H and} e _5L from the speed command control circuit 7 and the rotation speed corresponding signal e ₄ output from the microcomputer 6 to input the rotation speed and the speed command signal e. A deviation signal from ₅ is output to the pulse width modulator 42.

A pulse width modulation section (PWM) 42 receives the deviation signal and the inverter drive reference signal m and converts the deviation signal into a commutation control signal for pulse width modulation of each transistor of the inverter 3.

The limiter circuit 43 compares a voltage e ₉ proportional to the current flowing from the current detecting resistor 3 a of the three-phase inverter 3 to the transistor with a preset overcurrent value,
When voltage e ₉ is less than the overcurrent value and outputs a commutation control signal e _6, when the voltage e ₉ is equal to or greater than over-current value, all the transistors of the three-phase inverter 3 are turned off so that commutation control signal and outputs control the e _6.

The speed command control circuit 7 includes a filter circuit 71
, A speed command switching circuit 72, and a speed command circuit 73.

The filter circuit 71 inputs a voltage e ₉ proportional to the current flowing through the transistor from the current detection resistor 3 a of the three-phase inverter 3, stabilizes the capacitor so that malfunction and chattering do not occur, and sets the voltage e _10. Is output.

The speed command switching circuit 72 includes a filter circuit 7
When Enter the averaged voltage e ₁₀ output from the 1 larger than the threshold voltage e ₁₁ that the average voltage e ₁₀ is previously input set outputs a speed command switch signal e _12H high level,
The threshold voltage e averaging voltage e ₁₀ is previously input set
When small compared to _11L outputs a speed command switch signal e ₁₂ of the low-level.

The speed command circuit 73 includes a speed command switching circuit 7
From 2 when inputting the speed command switch signal e _12H high level high rpm that can be completed in a short time is degassing the vibration becomes large concrete outputs a speed command signal e _5H as for example a 12,000rpm Also, when the output signal of the speed command switching circuit is a low level signal, the vibration is reduced and the defoaming function of the concrete is low, for example, 6,000 rpm
The speed command signal _e5L is output so that

Next, the operation will be described. First, the driving of the motor will be described. The operation signal e ₈ is supplied to the microcomputer 6
, The microcomputer 6 outputs the inverter driving reference signal m to the commutation control circuit 4. The commutation control circuit 4 outputs a commutation control signal e ₆ corresponding to the drive reference signal m at the time of starting the inverter to the three-phase inverter 3. The three-phase inverter 3 receives the commutation control signal e from the commutation control circuit 4.
₆ and the transistor groups U +, V +, W +, U-,
V- and W- are turned on / off as required, and output lines 31 and 3 are controlled.
2, 33 output an AC voltage of 2-3 phase excitation (or 2 phase excitation). An initial exciting current flows through the three-phase stator winding 2 to dampen the permanent magnet rotor 1, and then an exciting current flows to generate a rotating magnetic field, and the permanent magnet rotor 1 is synchronized with the rotating magnetic field. Starts rotating.

After startup, the microcomputer 6 outputs an inverter driving reference signal m and a rotation speed corresponding signal e ₄ to the commutation control circuit 4 based on the rotation position signal e ₃ input from the rotation position detection circuit 5, The flow control circuit 4 receives the rotation speed corresponding signal e ₄ and the speed command signal e ₅ and receives the rotation speed corresponding signal e ₄ so as to eliminate the deviation of the rotation speed corresponding signal e ₄ from the speed command signal e _5H or e _5L. Determines the modulation width of the pulse width modulation. The pulse width modulation signal is transmitted to the three-phase inverter 3 through a limiter circuit 43 as a commutation control signal e _6.
And the three-phase inverter 3 controls the internal transistor groups U +, V +, W +, U−, V−, W− to turn on / off, and outputs the two-phase excitation AC voltage from the output lines 31, 32, 33. The motor is driven to output a sensorless brushless motor, an electric-mechanical energy conversion equivalent to that of a DC motor is performed, the permanent magnet rotor 1 is accelerated to a predetermined rotational speed, and the actual speed is changed to a speed command signal e _5H or e _5L. To match the command speed.

The speed command signals e _5H and e _5L depend on a change in a voltage e ₉ proportional to the current flowing from the current detection resistor 3a of the three-phase inverter 3 to the transistor. When the concrete vibrator is driven by inputting an operation signal e ₈ to the microcomputer 6 by hitting concrete, a voltage e ₉ proportional to the current flowing from the current detection resistor 3 a of the three-phase inverter 3 to the transistor is obtained as shown in FIG.
In (b), it rises up to the maximum value in a short time as a⇒b. Since the voltage e _{9 at the} point b indicates the maximum value and is higher than the threshold voltage e ₁₁ , the speed command switching circuit 72 outputs the high-level signal e
Outputs ₁₂ . Thus, the speed command circuit 73 inputs a high level signal e _12, since outputs a speed command signal e _5H so as to 12,000 rpm, the concrete vibrator motor becomes 12,000 rpm. For this reason, the vibration energy required for defoaming becomes large enough, defoaming is performed in a short time, and the amount of air bubbles remaining in the concrete is reduced in a short time as shown by cd in FIG. It shows a substantially hyperbolic change and decreases. Then, the voltage value and the work amount in FIG. 2B correspond to the hyperbolic change as shown by be or b'-e 'so as to correspond to the change in the bubble amount of cd in FIG. Shows decrease. Threshold voltage e ₁₁ is set to the speed command switching circuit 72 is a value when the voltage e ₉ has dropped to the point e. The time when the voltage e ₉ drops to the threshold voltage e ₁₁ is shown in FIG.
This is the point in time (a) in which the amount of air bubbles has decreased to d. At this point, compaction of the concrete is temporarily terminated. The amount of concrete components separated at this time is shown in FIG.
a small amount sufficiently by Q ₁ in (a). After this point,
You can go to the next concrete casting at any time.

When the voltage e ₉ drops to the threshold voltage e ₁₁ ,
Speed command switching circuit 72 outputs a low level signal e _12.
Thus, the speed command circuit 73 that inputs the low-level signal e ₁₂
, Since outputs a speed command signal e _5L so that the 6,000 rpm, concrete vibrator motor 6,000R.
pm. Therefore, the vibration energy required for defoaming is
Since the defoaming becomes extremely small at 12,000 rpm and the defoaming becomes extremely small, the change in the amount of air bubbles is small as shown by df in FIG. 2 (a). Also, when the motor reaches 6,000 rpm, the voltage value and the work amount are e-
gh or e'-g'-h '.

In the meantime, as shown in FIG. 2 (a), the separation amount of the concrete component becomes Q ₂ but 6,000 rpm
Since the gradient coefficient at the time of (1) is smaller than the gradient coefficient at 12,000 rpm, in FIG.
Even There elapse until substantially equal to the time A, since only Q ₂ is slightly larger than Q _1, sufficient compaction performed defoaming in a short time by increasing the conventional vibration energy as is Even if it can be done, the disadvantage that the component separation progresses greatly when the casting time is long and the strength of the concrete becomes brittle is solved. Note that it is preferable to secure the elapsed time B because the defoaming may occur even after the lapse of the tentative compaction time A. Then, after the time A elapses and the motor reaches 6,000 rpm, the vibration is so small that the worker can know that the compacting time has elapsed and start the next driving. You can know what is good.

Subsequently, when concrete is charged, the voltage e ₉ proportional to the current flowing from the current detection resistor 3 a of the three-phase inverter 3 to the transistor gradually increases, and after a short time p ₁ elapses, the threshold voltage e _11. Since the speed command switching circuit 72 switches again and outputs the high-level speed command switching signal _e12H , the speed command circuit 73
The speed command signal _e5H is output again at 12,000 rpm, and the motor of the concrete vibrator becomes 12,000 rpm (indicated by hi-j in FIG. 2 (b)). Therefore, when slight time p ₁ has elapsed the concrete from the charged, motor performs in a short time defoaming restored large vibration becomes 12,000 rpm, Therefore, the amount of bubbles remaining in the concrete, FIG. In FIG. 2 (a), the curve shows a substantially hyperbolic change in a short time, such as km, and decreases.
In (b), it decreases with a hyperbolic change like jk or j'-k '. Then, when the voltage e ₉ drops to the threshold voltage e ₁₁ , the speed command switching circuit 72 outputs a low-level speed command switching signal e _12L again, and the speed command circuit 73 outputs the speed command signal so that the speed command circuit 73 becomes 6,000 rpm. e Since _5L is output, the motor speed of the concrete vibrator is
At 6,000 rpm, vibration is reduced and defoaming is extremely reduced, and the increase in the amount of concrete components separated is suppressed. In FIG. 2A, the difference between the three peaks c, k, and n is due to the difference in the amount of concrete poured.

A second embodiment of the concrete vibrator of the present invention will be described with reference to a block circuit diagram of FIG. 3 and a graph of FIG. In the block circuit diagram of FIG. 3, components other than the speed command control circuit 7 are the same as those in FIG.
Since it is the same as the block circuit diagram of FIG.

The speed command control circuit 7 includes a filter circuit 71
, A speed command switching circuit 72, a speed command circuit 73, and a threshold voltage switching circuit 74.

The filter circuit 71 receives a voltage e ₉ which is proportional to the current flowing through the transistor from the current detecting resistor 3 a of the three-phase inverter 3, stabilizes the capacitor so that malfunction and chattering do not occur, and sets the voltage e _10. Is output.

The speed command switching circuit 72 includes a filter circuit 7
Averaging the voltage e ₁₀ output from 1 and the threshold voltage switching circuit 74
Threshold voltages e _11H output from, be adapted to enter the e _11L, averaged voltage e ₁₀ when the threshold voltage output from the threshold voltage switching circuit 74 is the threshold voltage (large) e _11H
Is smaller than the threshold voltage (large) e _{11H, a} low-level speed command switching signal e _12L is output. When the threshold voltage output from the threshold voltage switching circuit 74 is the threshold voltage (small) e _11L , the average is output. writing voltage e ₁₀ is is larger than the threshold voltage (small) e _11L outputs a speed command switch signal e _12H high level.

The speed command circuit 73 includes a speed command switching circuit 7
When a high speed command switching signal _e12H is input from 2, the vibration increases and the speed command signal for rotating the motor at a high speed such as 12,000 rpm at which the defoaming of concrete can be completed in a short time, for example. _e5H is output, and when a low-level speed command switching signal _e12L is input from the speed command switching circuit 72, the vibration is reduced and the defoaming function of the concrete is reduced to a low rotation speed, for example, 6,000 rpm. A speed command signal _e5L for rotating the motor at a low speed is output.

The threshold voltage switching circuit 74 branches and inputs the speed command switching signals e _12H and e _12L output from the speed command switching circuit 72 at a position before the speed command switching circuit 73 inputs the speed command switching signals. Speed command switching signal e _{12L for} low rotation from speed command switching signal e _12H for high rotation of the motor
, The threshold voltage (small) e _11L is switched to the speed command switching circuit 72 after the delay time m _{1 has} elapsed, and the speed command switching signal e _{12L for} rotating the motor at a low speed.
When switched to the speed command switch signal e _12H for high rotation is switched outputs the threshold voltage (large) e _11H after a delay time m ₂ passed the speed command switch circuit 72 from.

Accordingly, the speed command control circuit 7 detects the voltage e ₉ proportional to the motor current, and detects two large and small threshold voltages e 9
_11H or e _11L
When the detection voltage e ₉ With the introduction of the concrete is greater than the threshold voltage (small) e _11L, the speed command signal e for a high rotation of the motor to the vibration increases and the degassing can be completed in a short compaction times A _{When 5H} is output and the threshold voltage (small) e _11L is switched from the threshold voltage (large) e _11H to the threshold voltage (large) e _11H , and the compaction time A has elapsed and the detection voltage e ₉ becomes smaller than the threshold voltage (large) e _11H , A speed command signal e for lowering the speed of the motor so that the vibration is reduced again
_{It is configured} to output _5L and switch from the threshold voltage (large) _e11H to the threshold voltage (small) _e11L .

[0032] Upon inputting the operation signal e ₈ to the microcomputer 6, the threshold voltage switching circuit 74 is initially adapted to output a threshold voltage (small) e _11L to the speed command switch circuit 72, Therefore, the speed The command switching circuit 72 outputs a low-level speed command switching signal _e12L , and the speed command circuit 7
3 outputs the speed command signal _e5L so as to be 6,000 rpm, so that the motor of the concrete vibrator is 6,000 rpm.
It is designed to be driven at rpm.

Next, the operation will be described. Now, when the first concrete is put, the concrete vibrator is placed, and the operation signal e ₈ is inputted to the microcomputer 6, the voltage e ₉ proportional to the current flowing from the current detection resistor 3 a of the three-phase inverter 3 to the transistor is calculated as shown in FIG. In 4 (b),
It rises to the maximum value in a short time like a⇒b. Since the voltage e ₉ of the point b is higher than the threshold voltage (small) e _11L indicates the maximum value, speed command switch circuit 72 outputs a speed command switch signal e _12H high level. Accordingly, the speed command circuit 73 which has input the high-level speed command switching signal e _12H has a speed of 12,000.
Since the speed command signal e _5H is output so that the speed becomes rpm,
The concrete vibrator motor will be 12,000 rpm. For this reason, the vibration energy required for defoaming becomes large enough, the defoaming is performed in a short time, and the amount of air bubbles remaining in the concrete is reduced in a short time as shown by cd in FIG. It shows a substantially hyperbolic change and decreases. Then, FIG.
In FIG. 4B, the voltage value and the work amount are set to be or b'- in FIG.
It shows a hyperbolic change like e ′ and decreases. Detection voltage e
FIG. 4 shows the time when ₉ drops to the threshold voltage (large) e _11H .
This is the point in time (a) in which the amount of air bubbles has decreased to d. At this point, compaction of the concrete is temporarily terminated. The amount of concrete components separated at this point is shown in FIG.
a small amount sufficiently by Q ₁ in (a). After this point,
The next concrete can be charged at any time.

[0034] When the detection voltage e ₉ and compaction time A has elapsed falls to the threshold voltage (large) e _11H, speed command switch circuit 72 outputs a speed command switch signal e _12L of low level. Accordingly, since the speed command circuit 73 which has input the low-level speed command switching signal e _12L outputs the speed command signal e _{5L so} as to be 6,000 rpm, the motor of the concrete vibrator is 6,000 rpm. For this reason, the vibration energy required for defoaming is 1/4 of 12,000 rpm, and defoaming is extremely reduced.
The change is small like df of (a). Also, when the motor reaches 6,000 rpm, the voltage value and work amount are as shown in Fig. 4 (b).
, Respectively, to egh or e′-g′-h ′. During this time, since the amount of separation of the components of the concrete, as shown in FIG. 4 (a), the slope coefficient when the becomes a Q ₂ 6,000 rpm is smaller than the slope factor when the 12,000 rpm, FIG. 4 (a even after the elapse until) time a has elapsed time B in approximately equal to the time a, since only Q ₂ is slightly larger than Q _1, de in a short time by increasing the vibrational energy as in the prior art Even if sufficient compaction can be achieved by foaming, the disadvantage that component separation greatly progresses and the strength of concrete becomes brittle when the casting time is long is eliminated. Then, after the time A elapses and the motor reaches 6,000 rpm, the vibration is so small that the worker can know that the compacting time has elapsed and start the next driving. You can know what is good.

Then, the speed command circuit 73 is set to 6,000 rpm
When the speed command signal e _5L is output so that the threshold voltage switching circuit 74 detects the speed command signal e _5L , the threshold voltage switching circuit 74 detects the threshold voltage (small) e _11L when the delay time m ₁ has elapsed from the detection point. and switching the output to the speed command switch circuit 72, averaging the voltage e ₁₀ to be input to the speed command switch circuit 72 at this time is sufficiently smaller than the threshold voltage (small) e _11L. Accordingly, the speed command signal e _5L is output prior to the switching of the threshold voltage, and the threshold voltage is switched after the rotation speed of the motor reaches 6,000 rpm.
_Stably outputs a low-level speed command switching signal _e12L .

Subsequently, when concrete is charged, the voltage e ₉ proportional to the current flowing from the current detection resistor 3 a of the three-phase inverter 3 to the transistor rises almost without a time lag, and becomes higher than the threshold voltage (small) e _{11 L.} Becomes high again, the speed command switching circuit 72 switches and outputs the high-level speed command switching signal _e12H .
The speed command signal _e5H is output again at 12,000 rpm, and the motor of the concrete vibrator becomes 12,000 rpm (indicated by hi-j in FIG. 4 (b)). For this reason, when concrete is put in, the motor immediately returns to 12,000 rpm to greatly recover the vibration and degas in a short time.

Then, the speed command circuit 73 sets 12,000 rp.
When the speed command signal e _5H is output so as to be m, the threshold voltage switching circuit 74 detects this. When the delay time m ₂ elapses from the detection point, the threshold voltage switching circuit 74 _{sets the} threshold voltage (large) e _11H. was switched output to the speed command switch circuit 72, it is sufficiently larger than the averaged voltage e ₁₀ is the threshold voltage (large) e _11H for input to the speed command switch circuit 72 at this time. Therefore, the speed command signal e _5H is output prior to the switching of the threshold voltage, and the threshold voltage is switched after the rotation speed of the motor reaches 12,000 rpm.
2 stably outputs a high-level speed command switching signal _e12H .

As described above, when the motor is operated at 12,000 rpm after concrete is charged, the amount of air bubbles remaining in the concrete shows a substantially hyperbolic change in a short time as shown by km in FIG. 4 (a). In FIG. 4B, the voltage value and the work decrease and show a hyperbolic change like jk or j'-k '. Then, when the voltage e ₉ over time falls to gradually drop to the threshold voltage (large) e _11H, and outputs a speed command switch signal e _12L of low levels of the speed command switch circuit 72 again, the speed command circuit 73 Is 6,000rpm
The speed command signal e _5L is output so that the delay time m ₁
Has elapsed, the threshold voltage switching circuit 74 sets the threshold voltage (small)
e Since the _11L is switched and output, the motor speed of the concrete vibrator is reliably 6,000 rpm, vibration is reduced, defoaming is extremely reduced, and increase in the amount of concrete components separated is suppressed.

Although the concrete vibrators according to the above two embodiments each use a three-phase AC sensorless brushless motor, the present invention provides a motor control circuit that varies the motor speed based on a speed command signal. The present invention can be widely applied to motors that can be used.

[0040]

As described above, according to the concrete vibrator of the present invention, in the various construction works for casting concrete, when the concrete is started to be poured, the number of revolutions is automatically increased and the concrete becomes high. Vibration energy is applied to quickly degas the concrete, while defoaming is accelerated and when the compaction strength reaches a satisfactory level, the number of revolutions is automatically reduced to moderate the defoaming of the concrete. It can continue and suppress the promotion of separation of concrete components. According to the concrete vibrator of the present invention, it is not necessary to input and set a slump value according to the type of concrete, and it is not necessary to input and set a vibration time even if a compaction time changes due to a change in the amount of casting. According to the concrete vibrator of the present invention, the end of compaction can be determined without any input setting such as the vibration time. According to the concrete vibrator of the present invention, regardless of the type of concrete and the amount of casting, whether large or small, compaction can be performed in a short time, and the progress of component separation can be avoided even if the casting time is long, It can be used for concrete casting without skill.

[Brief description of the drawings]

FIG. 1 is a block circuit of a concrete vibrator according to a first embodiment of the present invention.

FIG. 2 (a) is a graph showing the relationship between the amount of air bubbles and the amount of separation and time when concrete is poured using the concrete vibrator according to the first embodiment of the present invention, and (b). Is a graph showing the relationship between voltage value and work amount and time when concrete is poured using the concrete vibrator.

FIG. 3 is a block circuit of a concrete vibrator according to a second embodiment of the present invention.

FIG. 4 (a) is a graph showing the relationship between the amount of air bubbles and the amount of separation and time when concrete is poured using the concrete vibrator according to the second embodiment of the present invention, and (b). Is a graph showing the relationship between voltage value and work amount and time when concrete is poured using the concrete vibrator.

Fig. 5 (a) shows a conventional concrete vibrator at 12,0
A graph showing the relationship between the amount of air bubbles and the amount of separation when rotating at 00 rpm and time, and (b) shows the relationship between the amount of work and the voltage value and time when rotating the conventional concrete vibrator at 12,000 rpm. (C) is a graph showing the relationship between the amount of air bubbles and the amount of separation when the conventional concrete vibrator is rotated at 6,000 rpm and time, and (d) is a graph showing the conventional concrete vibrator rotated at 6,000 rpm. 6 is a graph showing the relationship between the amount of work and the voltage value at the time and time.

[Explanation of symbols]

7 Speed command control circuit 71 Filter circuit 72 Speed command switching circuit 73 Speed command circuit 74 Threshold voltage switching circuit e _5H Speed command signal for rotating the motor at high speed e _5L · · · voltage e ₁₀ · · · averaged voltage proportional to motor speed command signal e ₉ · · · the motor current to a low rotational e ₁₁ · · · threshold voltage e _11H · · · threshold voltage (large) e _11L・ ・ ・ Threshold voltage (small) e _12H・ ・ ・ High level speed command switching signal e _12L・ ・ ・ Low level speed command switching signal

──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Tomio Kimura 15-1 Shimo-Osaki, Shirooka-cho, Minami-Saitama-gun, Saitama Mikasa Sangyo Co., Ltd. -1 Mikasa Sangyo Co., Ltd. (56) References JP-A-60-156865 (JP, A) JP-A-60-73962 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB (Name) E04G 21/08

Claims (2)

(57) [Claims] 1. A concrete vibrator using a motor capable of varying the motor rotation speed based on a speed command signal output from a speed command control circuit as a vibration source, wherein the speed command control circuit is proportional to a motor current. The voltage is detected and compared with a single threshold voltage that is set in advance.If the detected voltage becomes larger due to concrete input, vibration increases and degassing ends in a short compaction time The motor is rotated at a high speed so that the required frequency can be obtained, and when the compaction time has elapsed and the detection voltage is smaller, the motor is rotated at a low speed so that the required frequency slows down the progress of component separation. A concrete vibrator, characterized in that the vibrator is made to have a configuration. 2. A concrete vibrator using a motor capable of changing a motor rotation speed based on a speed command signal output from a speed command control circuit as a vibration source, wherein the speed command control circuit is proportional to a motor current. The voltage is detected and compared with one of the two threshold voltages, large and small. When the detected voltage becomes larger than the threshold voltage (small) due to concrete injection, vibration increases and compaction with short degassing is performed. The motor is rotated at a high speed so as to reach a required frequency that can be completed in time, and the threshold voltage (small) is switched from the threshold voltage (large) to the threshold voltage (large). When it is smaller than the threshold value, the motor is rotated at a low speed so as to reach a required frequency at which the progress of component separation is slow, and the threshold voltage (large) to the threshold voltage (small)
A concrete vibrator characterized in that the vibrator is configured to switch to a concrete vibrator.