JPH0656386B2 - Particle flow detector - Google Patents

Description

FIELD OF THE INVENTION This invention relates to capacitive flow detectors.

2. Description of the Related Art Conventionally, this type of flow detector is configured as shown in FIGS. 19 and 20. Reference numeral 1 denotes an electrostatic capacitance detection electrode, which is inserted into a resin pipe 3 through which the particles 2 pass, and an electronic circuit [not shown] attached at a position different from the pipe 3 and the electrode 1 Are connected by a cord 4 and the change in capacitance between the electrodes 1 is measured by the electronic circuit to determine the flow state of the granules 2. In addition, the electrode interval 1 is set to be sufficiently larger than the particle diameter of the particles to be measured.

Problems to be Solved by the Invention In such a conventional configuration, since the amount of protrusion of the electrode 1 to the inside of the pipe 3 is large, the flow of the granules 2 is hindered,
You cannot expect a smooth drop of particles.

It is an object of the present invention to provide a flow detector that does not hinder the fall of particles and that can be expected to measure with higher sensitivity.

Means for Solving the Problems A particle flow detector of the present invention is for detecting a pair of capacitances composed of a ground electrode and a hot electrode along an inner peripheral surface or an outer peripheral surface of a particle passage forming member. An electrode is provided, and a detection circuit is provided to detect the flow state of the particles based on the capacitance change between the capacitance detection electrodes, and the distance between the ground electrode of the capacitance detection electrode and the hot electrode in the particle passage direction is measured. It is characterized in that it is configured to be approximately equal to the particle diameter of the target granules.

Action According to this configuration, since the capacitance detection electrode is provided along the inner peripheral surface or the outer peripheral surface of the particle passage route forming member,
When it is provided along the inner peripheral surface, the amount of protrusion into the particle passage path is small compared to the conventional case, and when it is provided along the outer peripheral surface, the amount of protrusion can be zero, and You can expect a smooth fall. Moreover, since the width of the capacitance detection electrode is set according to the particle diameter of the measurement target particle, it is possible to perform measurement with higher sensitivity than before.

Embodiment An embodiment of the present invention will be described below with reference to FIGS. 1 to 18.

FIG. 1 shows that a conductive portion such as a copper foil is directly attached to the outer peripheral surface A of the resin pipe 3 and the hot electrode 5 and the ground electrodes 6 ₁ , 6 ₂ are attached.
Are formed, and the hot electrode 5 and the ground electrode 6 ₁ ,
The change in capacitance between the _two is measured by a detection circuit (not shown) to determine the flow state of the particles 2 passing through the pipe 3.

With this configuration, the electrodes 5, 6 ₁ , 6 ₂ as the electrodes for outputting electrostatic capacitance do not appear as protrusions in the internal passage B ₁ of the pipe 3, and thus do not hinder the passage of the granules 2.

Electrodes 5,6 1 on the outer peripheral surface A of the pipe 3 in Figure _1, 6 ₂ but was provided which, as shown in partial cut-away view of FIG. 2,
Electrodes 5,6 1 by sticking the conductive portion such as the copper foil directly on the inner peripheral surface C of the pipe _3, is the same to form a 6 _2. However, in this case, a protrusion corresponding to the thickness of the conductive portion is generated in the internal passage B ₁ of the pipe 3, but since it is very small, it does not hinder the passage of the granules 2.

Although the formation of the electrodes 5, 6 _1, 6 ₂ by sticking the conductive portion in the embodiment of Figure 1 and Figure 2, which is also by printing a conductive paint irrespective of the attached The same effect can be obtained.

Electrodes 5,6 1 on the outer periphery or the inner periphery of the tubular pipe 3 in Figure 1 and Figure _2, 6 ₂ was formed, this third view without using a pipe 3, as FIG. 4 Can be configured.

Figure 3 is a flexible wiring board 7 on which a pattern of electrodes 5, 6 _1, 6 ₂ are formed, which was wound up in a cylindrical shape with the pattern surface D on the outside, granules 2 backside E of the pattern surface D It passes through the internal passage B ₂ surrounded by.

In FIG. 4, the pattern surface D is rolled up in a tubular shape, and the particles 2 pass through the internal passage B ₂ surrounded by the pattern surface D.

5 and 6 show an embodiment in which the pipe 3 and the flexible wiring board 7 are combined, and the flexible wiring board 7 is covered on the outer peripheral surface A of the pipe 3. In this case, the pattern surface D of the flexible wiring board 7 is arranged on the outer peripheral surface A side of the pipe 3 and wound up, or the back surface E is arranged on the outer peripheral surface A side of the pipe 3 and wound up. FIG. 7 shows a specific example of FIG. 5, in which the flexible wiring board 7 is pressed against the outer peripheral surface A of the pipe 3 by the annular caps 8 ₁ and 8 ₂ , and the pipe 3 is placed outside the caps 8 ₁ and 8 _2. A cylindrical shield case 9 is covered so as to surround the. 10 is a hollow part, which helps reduce the stray capacitance.

In the embodiment of FIG. 5, the flexible wiring board 7 is covered on the outer circumference of the pipe 3, but this is the same even if the flexible wiring board 7 is inserted inside the pipe 3 as shown in FIGS. 8 and 9. . In this case, the internal passage B _{1 of the} pipe 3
Although a protrusion corresponding to the thickness of the flexible wiring board 7 is generated, it does not hinder the passage of the granules 2 because it is extremely small. In the embodiment of FIGS. 8 and 9, the pattern surface D is inserted with the inner peripheral surface C side of the pipe 3 or the back surface E is inserted.
Is inserted with the inner peripheral surface C side of the pipe 3 facing.

FIG. 10 shows the positional relationship between the detection circuit 11 which determines the flow state of the particles based on the change in capacitance and the pipe 3 as a passage forming member. Here, the detection circuit 11 is arranged in the vicinity of the pipe 3 of the embodiment shown in FIG. ₁ , and the detection circuit 11 and the electrodes 5, 6 ₁ , 6 ₂ are connected to each other without a long cord, thereby floating. The capacity can be reduced and the whole can be made compact. Reference numeral 12 is a cable used for applying a power supply voltage and outputting a flow state determination signal.

FIG. 11 shows a usage state in which the pipe 3 as a passage forming member is inclined by an angle θ with respect to the vertical direction. In this way, granules 2 is securely on the inner peripheral bottom 13 of the pipe 3, the position becomes reliably pass close to electrodes 5, 6 _1, 6 _2, a pipe as in FIG. 14 The detection sensitivity is significantly improved as compared with the case where the granular material 2 is flown by mounting 3 directly in the vertical direction.

The effect obtained by the mounting position of the detection circuit 11 as shown in FIG. 10 and the inclined mounting as shown in FIG. 11 is not limited to the embodiment shown in FIG. 1 but also shown in FIG. 2, FIG. 3, FIG. The same is obtained in any of the embodiments shown in FIGS.

12 to 14 show the relationship between the electrode spacing and the particle size d of the particles to be measured. As shown in Fig. 12 (a), the hot electrode 5 is attached to the pipe 3.
When the ground electrode 6 and the ground electrode 6 are provided, the electrostatic capacitance value [basic capacitance value C ₀ ] of the electrodes 5 and 6 in a state where the particle 2 does not pass is
As shown in FIG. 13, it becomes smaller as the electrode spacing L ₁ becomes larger. When the granules 2 pass, the capacitance changes by ΔC and C ₀
The capacitance value of + ΔC is shown. ΔC is larger as the electrode interval L ₁ is smaller, but the distance h between the detectable granular particle 2 ′ and the electrode is h.
As shown in FIG. 14, the larger the electrode spacing L ₁ is, the larger the distance can be monitored. Therefore, ΔC, h
In order to improve both of them, it is preferable to set the electrode interval to L ₂ which is substantially equal to the particle diameter (d) as shown in FIG. 12 (b).

The effect of high sensitivity measurement by setting L ₂ d is the same in the embodiments of FIGS. 2, 3, 4, 5 and 8.

FIG. 15 shows a specific configuration of the detection circuit 11. 16 is an oscillator,
As shown in FIG. 16 (a), an AC signal of constant voltage V ₀ is generated. 1
Reference numeral 7 denotes a resonance section for extracting a signal of the oscillation section 16, whose fundamental center frequency is set at or near the signal frequency of the oscillation section 16, and the resonance frequency changes according to the ΔC component.
Here, when the interelectrode capacitance is C ₀ [when it is empty],
As shown in Fig. 16 (b), an AC signal with the same signal frequency and a peak value lower than V ₀ is generated at the output of the resonance part 17, and the granules 2 exist in the passage forming member and move with the granules 2. Not (C ₀ +
In the case of ΔCmax) [when it is clogged], an AC signal having the same signal frequency and a peak value lower than that in FIG. 16 (b) is generated at the output of the resonance part 17 as shown in FIG. When the granules 2 are moving in the member [C ₀ + ΔC] [in flow], the signal frequency is the same as in Fig. 16 (d), and the crest value varies depending on the flow state. An AC signal that changes between (d) and (c) is generated at the output of the resonance unit 17. Reference numeral 18 denotes a detection unit that converts an alternating current signal generated at the output of the resonance unit 17 into a DC level signal St. The signal waveforms of FIGS. 16 (b), (c), and (d) are V ₁ , respectively. Converted to V ₂ and V ₃ . In addition, V ₁ >
V ₃ > V ₂ . Reference numerals 19 and 20 denote amplifiers, and the amplification factor is "1" here. Reference numeral 21 denotes a first comparator, which compares the occasional signal St of the detector 18 with the reference signal R ₁ of the DC level V ₁ via the amplifier 19. A second comparator 22 compares the level of the signal St with the reference signal R ₂ of the DC level V ₂ . Here, for convenience of explanation, the output O _{2 of} the first comparator 21 is inverted to the “H” level when the level of the signal St reaches V ₂ , and the second comparator 22 outputs the signal St of which the level is V ₂ It is assumed that the output O ₂ inverts to the “H” level in the state where the temperature reaches 0. Reference numeral 23 denotes a gate portion to which the signals of the outputs O ₁ and O ₂ are applied to the input, the output O ₁ is at “H” level and the terminal T ₁ is at “H” level, and the output O ₂ is at “H” level terminal T ₃ Is set to the "H" level, the outputs O ₁ and O ₂ both set the "L" level terminal T ₂ to the "H" level, and when the terminal T ₁ is inverted to the "H" level, the empty state, the terminal It can be seen that when T ₂ is inverted to the “H” level, it is in a flow state, and when the terminal T ₃ is inverted to the “H” level, it is a blocked state.

In each of the above-described embodiments, the capacitance detection electrode is 1
Although one hot electrode 5 and two ground electrodes 6 ₁ and 6 ₂ are provided, the number of electrodes and the shape of the electrodes are not limited to those in the above-described embodiment, and the capacitance detection electrode is a hot electrode and a ground electrode. It suffices if at least one pair is provided.

FIGS. 17 and 18 are development views of the flexible wiring board 7 effective for use in the embodiments of FIGS. 3, 4, 5, and 8, respectively. It is the direction of passage. _Here, 5 1, _{5 2} hot electrode _{6 1, 6} 2, 6
Reference numeral ₃ is a ground electrode, and in FIG. 17, the hot electrodes are connected to each other and the ground electrodes are connected to each other by the patterns 14 ₁ and 14 ₂ of the flexible wiring board 7. Also, the 18th
In the figure, the external lead wires 15 ₁ connect the hot electrodes to each other, and the ground electrodes connect to each other by the external lead wires 15 ₂ and 15 ₃ . The electrode interval is a pattern formed on L ₂ d as described in FIG. 12 (b).

EFFECTS OF THE INVENTION As described above, according to the present invention, the particle flow detector of
Since more than one pair of capacitance detection electrodes consisting of a ground electrode and a hot electrode are provided along the inner peripheral surface or the outer peripheral surface of the particle passage route forming member, the amount of protrusion of the detection electrode into the particle passage route is reduced. Since it is zero or a very small amount, it is possible to determine the flow state without disturbing the flow of the particles.

Furthermore, in the present invention, since the distance between the ground electrode of the capacitance detection electrode and the hot electrode in the particle passage direction is configured to be substantially equal to the particle diameter of the measurement target particle, it is possible to use a highly sensitive and minute particle as compared with the conventional one. Even if there is, this flow state can be detected and judged.

[Brief description of drawings]

FIG. 1 is a perspective view of an essential part of the first embodiment of the present invention, FIG. 2 is a partially cutaway perspective view of the second embodiment, and FIG. 3 is a perspective view of an essential part of the third embodiment. FIG. 4 is a partially cutaway perspective view of the fourth embodiment, FIG. 5 is a schematic perspective view of the fifth and sixth embodiments, and FIG. 6 is a plan view of FIG. FIG. 8 is a partially cutaway front view showing a specific example of FIG. 5, and FIG. 8 is a seventh embodiment and an eighth view.
FIG. 9 is a schematic perspective view of the embodiment of FIG.
FIG. 11 is a perspective view showing the positional relationship between the passage forming member and the detection circuit, FIG. 11 is a partially cutaway perspective view showing the mounting posture of the passage forming member, and FIGS. 12, 13 and 14 are granules. Explanatory drawing of particle diameter and electrode size for capacitance detection, FIG. 15 is a configuration diagram of a detection circuit, FIG. 16 is a waveform diagram of essential parts of FIG. 15 according to a flow state,
17 and 18 are development views of the flexible wiring board, FIG. 19 is a perspective view of a main part of a conventional flow detector, and FIG. 20 is a horizontal sectional view of FIG. 2 ...... granules, 3 ...... pipe, 5 ...... hot _{electrode, 6} 1,
6 ₂ ...... Ground electrode, 7 ...... Flexible wiring board,
9 ...... shield case, 11 ...... detecting circuit, d ...... granular particle size, L 2 _...... electrode spacing.

Claims (1)

[Claims] 1. A capacitance change between electrodes for capacitance detection, wherein a pair of electrodes for capacitance detection consisting of a ground electrode and a hot electrode are provided along the inner peripheral surface or the outer peripheral surface of a particle passage forming member. A particle which is provided with a detection circuit for detecting the flow state of the particle from the particle, and the distance between the ground electrode and the hot electrode of the capacitance detecting electrode in the particle passage direction is substantially equal to the particle diameter of the particle to be measured. Flow detector.