JPH0789151B2 - M type deep rebar probe - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention is an apparatus for exploring the location of reinforcing bars in existing reinforced concrete, which is generally used in the civil engineering and building industry, and is not available in this type of prior art. The present invention relates to an M type deep rebar prober capable of probing the location of rebars that have been possible, and particularly located deep inside concrete.

[Prior Art] As a first prior art, FIG. 5 shows a circuit configuration diagram of an existing reinforcing bar exploration unit which has been manufactured and used up to now. The outline is that the constant low frequency voltage vi output from the oscillator 31
Is supplied to the sensor coil 32 whose inductance changes by bringing it closer to the reinforcing bar. The output voltage vo from the sensor coil 32, which is proportional to the inductance of the coil 32, is amplified by the Log amplifier 33, the amplifier 34, and the gain enable amplifier 35. This is because the change in inductance is generally small and it is necessary to amplify the inductance appropriately.

Further, when the reinforcing bar is close to the coil, the change in L has a large value, and when it is far away, the change in L is small, and the change in L is nonlinear with respect to the distance.

The log amp 33 is used to compress the change in L with respect to the change in distance. Further, the amplifier 34 is used for the purpose of the output zero adjustment function and linear amplification. Further, in order to adjust by the diameter of the reinforcing bar, the resistance value of the feedback circuit of the amplifier is changed by an external changeover switch so that the gain of the amplification section is made to pass through the circuit. After that, in order to display the output on the meter, the buffer circuit 36 is passed through and the location of the reinforcing bar is displayed on the meter 37.

As a second conventional technique, a “reinforcement probe using resonance” relating to the same inventor and the same applicant as the present application (application number:
Japanese Patent Application No. 63-200373), and FIG. 6 (a) shows a circuit configuration diagram thereof, and FIG. 6 (b) shows a relationship between frequency and voltage at resonance.

The present invention will be described with reference to FIG. 6 (a). First, a constant low frequency (1250 [Hz]) voltage is supplied from the resonator 45, passes through the buffer circuit 41, and is applied to the resonance circuits L and C.

First, as described above, the coils constituting the resonance circuit (L, C) of the present invention probe are supplied with power at a frequency slightly shifted from the resonance point of this resonance circuit, and in this state, resonance occurs. The first output from the circuit and the second output which is the output of the oscillator 45 which is the power supply for the resonance circuit and which does not pass through the resonance circuit are matched in phase and compared by the differential amplifier 48. First, preparation is made so that the first and second outputs become equal, that is, the differential amplifier output becomes zero.

Next, in the exploration operation, when the probe coil approaches the metal body, the output of the first output decreases almost proportionally along its resonance curve, and the differential output is obtained from the differential amplifier 48. However, since this difference output may include an unnecessary frequency due to a distortion component, this difference output is filtered by the filter 49, and further, the instrument is passed through the lock-in amplifier 50 synchronized with the original frequency signal from the oscillator. Output to 51.

This instrument output is the difference between the output signal when the rebar is not near the coil and the output signal when the rebar is near, in other words, data on the degree of proximity of the rebar to the coil, that is, the burial depth. .

When actually operating the device, an angular frequency ω ₁ or ω ₂ which is deviated only slightly from the perfect resonance state is used. The reason for this is that ω ₁
Or, if it is set to ω ₂ , even if the inductance changes, the output voltage drops sharply in almost monotonous proportion to the frequency, and compared with the change in frequency near the resonance point, ω ₁
Alternatively, if it is ω ₂ , the change of the output voltage with respect to the frequency becomes large, and therefore, higher sensitivity can be obtained as compared with the commercially available probe of the first technology.

The relationship between the angular frequency ω ₁ or ω ₂ and the resonance curve is as shown in FIG. 6 (b), and the voltage at the intersection of the dotted line of ω ₁ or ω ₂ and the resonance curve is displayed on the meter. , It is a number related to the depth of rebar discovered by exploration.

[Object of the Invention: Problem to be Solved] However, since the above-mentioned first conventional technique uses the transistor for the oscillator, the frequency easily changes depending on the temperature and the proximity of the reinforcing bar, and the sensor is an air core. Since it is only the coil of No. 2, even if it approaches the rebar, the change of the magnetic field is small and it cannot be accurately detected. Furthermore, since a high frequency is not used and a low frequency of about 1250 [Hz] is used, the current that can be passed through the coil is also small, so the power consumption is small, the depth limit is shallow, and no resonance circuit is used. However, it has a low sensitivity and therefore the depth of the rebar to be searched is only 5 to 6 [cm] in the concrete, and there is a drawback that the deeply buried rebar cannot be searched at all. Next, since the second conventional technique uses the L and C resonant circuits, the precision is considerably higher than that of the first conventional technique, and the depth to which deep inspection is possible is 10 or less.
It is about 15 [cm], which is a considerable improvement over the first prior art, but there were still some problems in the following points. That is, first, an oscillator with a normal function such as a transistor or IC is used, and the oscillation frequency is 10 to 15 [KH
It is a so-called middle frequency of about z], and the accuracy is not so high because the frequency slightly changes due to temperature changes. In addition, since the IC is used as a buffer, the usable current is as small as a few mA, so the power input to the resonant circuit is also small and the magnetic field generated is weak, so the accuracy of exploration is 10-
It is about 15 [cm], which is a considerable improvement over the first prior art, but there is a problem that it is still insufficient.
Moreover, as shown in FIG. 6 (b), since a frequency slightly deviated from the true resonance frequency is used, the highest peak of the resonance curve is not used, but a voltage slightly lower than that is used. Therefore, there is a problem that the accuracy is not enough even with this. Furthermore, since the resonance circuit and the phase shifter are arranged in parallel, the influence on the temperature change is different. Therefore, there is a problem that the accuracy is slightly lowered when the temperature changes.

INDUSTRIAL APPLICABILITY The present invention eliminates and improves the various drawbacks and problems of the above-mentioned prior art as much as possible, enables exploration in concrete far deeper than conventional ones, has higher accuracy, and is hardly affected by temperature change. The purpose is to develop and provide a deep rebar probe that maintains high accuracy.

[Configuration of the Present Invention: Means for Solving the Problem] The features of the means for solving the problem of the present invention, in other words, the configuration of the present invention, which are clearly different from the conventional art, are as follows. That is,
For the purpose of detecting the state of the reinforcing steel in the deep part of the existing concrete, a predetermined high frequency voltage is input in parallel from two high frequency oscillators fed from a power source to two resonant circuits of the same shape and rating that are provided in parallel. To be done. The input side of each resonance circuit is provided with a power amplifier for electric power, which is not used in the prior art, and the output side of each resonance circuit is provided with an amplifier.

Thus, one of the above two resonance circuits can be easily held by hand as a probe for exploring rebar in concrete,
Alternatively, the other may be configured as a movable type, and the other may be used as a reference resonance circuit composed of a coil and a variable or fixed capacitor so as to have the same frequency as that of the sensor, and the coils may be coupled by magnetic field lines. Configure not to. The outputs of these two resonant circuits are respectively amplified by passing through different amplifiers in parallel, the outputs of these two are input to a single differential amplifier, and the output of the difference is limited to the predetermined high frequency of the original oscillator. However, in order to remove signals of other frequencies, a phase-locking detection function by a lock-in amplifier directly connected from the oscillator and a means for displaying its output by a meter are taken. The high frequency frequencies generated by the oscillators described above are much higher than those used in the prior art.
A high-frequency magnetic field is strongly generated by using 10 [MHz] or more of [KHz]. A crystal oscillator is used for the oscillator so that the oscillation frequency does not change due to temperature or the like. Next, a power amplifier uses a power semiconductor element, which includes a power MOS, a power transistor, and a SIT. In addition, the core is inserted into both or one of the two resonance circuits provided in parallel. Moreover, the configuration is different from the conventional one in that the coil may be inserted into the pot-shaped ferrite of the reference resonance circuit.

The variable capacitor has the same function as that of the fixed capacitor if the adjustment position is fixed at one position if necessary.

[Operation] The M type deep rebar prober according to the present invention is
Since there is a special effect that the reinforcing bar can be explored in the concrete to a position that is more than twice as deep as the conventional one, the operation will be described in detail.

That is, in the present invention, a configuration different from the prior art is adopted in many respects, and each element has an action different from the conventional one. First, the first point is used in an amplifier and in this kind of device. Since the power semiconductor device, which has never been used, is used, a high power output can be used at a frequency significantly higher than the conventional one. Further, since the coil is inserted in the pot-shaped ferrite of the reference resonance circuit, there is also an effect that sensitivity is particularly improved without being affected by other magnetic field lines in the surroundings.

In such a case, the output voltage V ₀ of the resonance circuit is expressed as follows.

In the equation (1), R is a magnetic resistance, R ₀ is a DC resistance of a coil, c is a capacitance of a capacitor, ω is an angular frequency, j is a complex number, and V ₁ is an input voltage.

Further, assuming that the magnetic resistance inside the core in the coil is R ₁ and the magnetic resistance outside the core where the magnetic flux passes is R ₂ , R = R ₁ + R ₂ , and in the present invention, the coil is placed in the pot-shaped ferrite of the reference resonance circuit. Since it is inserted, a magnetic field much stronger than the conventional one is formed in combination with the use of high power and high frequency.

Therefore, when the probe of the resonance circuit as the sensor approaches the rebar in the concrete, it reacts with high sensitivity, and the magnetic resistance R ₂ outside the core reacts more sensitively than before.

More specifically, the resonance circuit as a sensor and both coils of the reference resonance circuit have no magnetic coupling relationship, so that the coil of the reference resonance circuit should not be magnetically coupled to the other coil. , I put a coil in the pot-shaped ferrite and made it resonate. The sensor coil emits magnetism in the form of a magnetic flux gun toward the rebar in the deep part, and utilizes the interaction of the sensor coil with the magnetism from another external magnetic flux generator. The magnetism of this should also not affect the reference coil. Such a constitutional action does not exist in the prior art at all, and is one of the features only in the present invention.

In the general formula of one resonance circuit, at resonance, ωL = 1 /
ωc, and the output voltage V ₀ at this time is Is the same as in the normal case.

In the case of the present invention, in addition to the above-described action of high accuracy, two resonant circuits having the same size and rated temperature characteristics are used in parallel. Since it is not affected by the change at all, in reality, only the change in the magnetic force when the probe approaches the rebar is output, amplified, and the difference is further amplified. By using, only the signal of a predetermined frequency will be displayed on the meter with high sensitivity.

Therefore, as an action of the present invention, it is possible to accurately search for a reinforcing bar located at a depth more than double that of the prior art.

[Embodiment] FIG. 1 is a circuit diagram showing an embodiment of the present invention. The high-frequency voltage oscillated by the oscillator 1 is connected in parallel, and corresponding component elements having the same function are respectively input to two resonant circuit systems having the same rating. That is, the resonance circuit 3 as a sensor and the amplifier 5 are further connected in series through the first power amplifier 2. Through the second power amplifier 2 ', a resonance circuit 4 as a reference circuit is connected in series, and an amplifier 5'is further connected in series.

Further, if these two circuit systems are compared laterally, the power amplifiers 2 and 2 ', the resonance circuits 3 and 4, and the amplifiers 5 and 5'have the same ratings, respectively. The outputs of the resonance circuit systems are input to the same differential amplifier 6, respectively, and after the difference between them is amplified, they are directly connected to the lock-in amplifier 7 from the oscillator 1 to conduct a predetermined high frequency voltage. The output of the lock-in amplifier 7 is input only to the predetermined high frequency signal and is input to the meter 8 and displayed. In the present invention, a high frequency of 10 [KHz] to 10 [MHz] is used as this high frequency.

Further, the resonance circuit 3 of the first resonance circuit system is composed of a coil 3L and a capacitor 3c, of which the coil 3L is provided in an exploration probe, and the exploration probe is formed as a handy type, and the concrete surface is a human being. In the hands of
Or it is made to be easy to move along a simple rail.

Furthermore, the resonance circuit 4 of the second resonance circuit system is a coil.
It is composed of 4L and a capacitor 4c, and together with the element parts other than the coil 3L, it is put together in one or a few boxes as a probe.

The feature of the embodiment of the present invention is that, in addition to the configuration which is completely different from the same rated parallel resonant circuit of the above-mentioned respective parts, a further particularly different point is that a FET is used as an amplifier to form a power amplifier. A power transistor may be used instead of the power MOS FET, and the fact that a high power amplifier is used for the first time in this type of equipment is also a significant feature.

In addition, in the reference resonance circuit, the coil is inserted in the pot-shaped ferrite, which has a particularly large effect of increasing the magnetic force, which is a considerable feature not seen in the conventional example.

Next, the operation of the deep rebar prober of this embodiment will be described in detail. First, in the present embodiment, the frequency of the high frequency voltage generated from the oscillator 1 is set to 100 [KHz], which is about 5 to 2 times that of the conventional frequency. The use of high-frequency, high-power power in such a high-power amplifier
Due to the use of FET.

The operation and theory of one resonance circuit is the same as in the usual case, but the difference from the conventional one is that the use of a high frequency, which is not used in the related art, exceeds the conventional level. A strong line of magnetic force is generated from the probe coil 3L, and the effect of detecting the change in the line of magnetic force due to the presence of reinforcing bars can be obtained even in a very deep portion of concrete. As a result, the sensitivity is also significantly higher than before.

FIG. 2 shows the backing of this embodiment of the present invention.
It shows the experimental results on the explorable depth of the reinforcing bars embedded in concrete. That is, in FIG. 2, the vertical axis represents relative output (voltage), the horizontal axis represents the distance from the sensor,
In other words, it indicates the depth in the reinforced concrete that became detectable. According to this, it became possible to detect sufficiently at a depth of about 60 [cm], which was possible in the past.
Compared to 10 to 15 [cm], the depth is more than double,
It was possible to confirm the location of the reinforcing bars. The diameter of the reinforcing bar in the concrete used in the experiment of this example is 20.
It was [mm].

FIG. 3 is an experimental result for discovering the vertical shortest left and right positions from the concrete surface after the location of the reinforcing bar in the concrete can be detected. As a result of moving the probe to the left and right, the point at which the highest output is obtained is set to 0, and the change in the output is represented. If a rock drill is applied to this position of 0 to dig, it becomes possible to find the reinforcing bar in the minimum time.

Next, in the embodiment of the present invention, the first resonance system circuit and the second resonance system circuit
Since the resonance circuits of the same type have exactly the same rating, there is no measurement error due to temperature changes, so changes in magnetic flux due to the presence of reinforcing bars in concrete can be measured. Therefore, since the output of the magnetic flux change is obtained with high accuracy by the differential amplifier 6, the result with high accuracy is also displayed on the meter 8, and the explorable depth of the reinforcing bar in concrete is more than double that of the conventional one. It became big. Although the meter 8 is one of the display means, it includes all analog and digital systems. Further, FIG. 4 is a comparison diagram of the output (differential amplifier outlet) and the angular frequency of the present invention and the second prior art {shown in FIG. 6 (b)} regarding the experimental results of this embodiment. .

That is, in the conventional state, since low frequency and low power are used, ω ₁ ,
Since I was exploring the rebar at a low position of ω ₂ ,
Low sensitivity, as a result the searchable depth of the reinforcing bar in the concrete was relatively shallow, but in the present invention, since it is possible to measure the angular frequency of the resonance point itself, more accurately, of the reinforcing bar in the deep position. Exploration became possible.

[Effects of the Present Invention] (1) In the present invention, the circuit of the prior art is completely different, and two resonant circuit systems each composed of component elements of the same rating are arranged, one of which is a probe and the other is a reference circuit. As
Since the change in magnetic flux due to the presence of rebar is measured, there are no errors due to differences in circuit characteristics or changes in temperature, so it is more accurate than before and up to a depth of about 3 times or more, that is, about 60 [c
It is possible to accurately search up to a depth of [m].

(2) In the present invention, since the power amplifier using the power semiconductor element which has never been used in the probe of this kind has been used for the amplifier, it becomes possible to use high frequency and large power. It becomes possible to obtain the resonant angular frequency with high accuracy, and as a result, it is possible to probe the reinforcing bar up to about 3 times more than the conventional one, to the depth of concrete, that is, to the depth of about 60 [cm]. became.

(3) In the present invention, in the reference resonance circuit, the coil is inserted in the pot-shaped ferrite that has a particularly large effect of increasing the magnetic force. Up to a depth of about 60 [c
It has become possible to explore the rebar to a depth of [m]. In other words, this means that a deep rebar prober has been created with a precision that is about three times higher than that of the prior art.

[Brief description of drawings]

FIG. 1 is a “block diagram showing a circuit of an M type deep reinforcing bar surveying device” according to the present invention, and FIG. 2 is a “block diagram showing a distance between a sensor tip and a reinforcing bar in concrete and an output of the M type deep reinforcing bar surveying device of the present invention. Table showing relations ", Fig. 3 is" figure showing relation between position of lateral movement of probe and output "of M type deep rebar prober of the present invention,
FIG. 4 is a “comparison diagram of the present invention with respect to output (differential amplifier outlet) and angular frequency and second prior art” regarding the M type deep rebar prober of the present invention, and FIG. 5 is “first prior art”. FIG. 6 (a) is a “block diagram showing a circuit of a second conventional technique”, and FIG. 6 (b) is a “block diagram showing a relationship between an angular frequency and an output in the second conventional technique”. FIG. 1 ... Oscillator, 2, 2 '... Power amplifier, 3 ... Resonance circuit as sensor, 4 ... Resonance circuit as reference circuit,
3L, 4L …… coil, 3C, 4C …… capacitor, 5,5 ′ …… amplifier, 6 …… differential amplifier, 7 …… lock-in amplifier, 8
…… Meter.

Claims (6)

[Claims] 1. A variable or fixed oscillator for generating a predetermined high-frequency voltage and a coil connected to the oscillator through a power amplifier to serve as an exploration probe for the purpose of detecting the state of a reinforcing bar in a deep part of existing concrete. A resonance circuit for a sensor, which is composed of a capacitor and outputs a change in inductance generated as a voltage change by inputting a voltage having a frequency close to its resonance point from the oscillator and approaching a reinforcing bar in concrete, and is equivalent to the power amplifier. , And another resonance circuit connected in parallel to the sensor resonance circuit in series to another power amplifier connected in parallel, and a coil and a variable or fixed capacitor having the same frequency as the sensor. And a reference resonance circuit composed of, and output terminals of both resonance circuits are respectively connected via an amplifier, and A differential amplifier that calculates and amplifies the output difference of the resonance circuit, and a lock-in amplifier that receives the output of the differential amplifier, and from which the predetermined high-frequency output from the oscillator is directly input as a reference signal to perform a limited operation. An M type deep rebar prober comprising: 2. The M type deep rebar prober according to claim 1, wherein the frequency of the predetermined high frequency is 10 [KHz] or more and 10 [MHz] or less. 3. The M type deep rebar prober according to claim 1, wherein the oscillator is an oscillator using a crystal oscillator. 4. The M type deep rebar prober according to claim 1, wherein the power amplifier is a semiconductor device for electric power. 5. The M-type deep rebar prober according to claim 1, wherein one or both of the sensor resonance circuit and the reference resonance circuit are resonance circuits in which a core is inserted in a coil. 6. The M type deep rebar prober according to claim 1, wherein the reference resonance circuit is a resonance circuit in which a coil is inserted in the pot-shaped ferrite.