JPH0583148B2 - - Google Patents

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an impedance detection device for a filter (hereinafter referred to as a contaminant filter) that removes contaminants from a fluid. Impedance between the filter element and a predetermined position of the fluid, and between the filter element and the filter case, which constitute a filter that filters liquids such as solvents and lubricating oils to remove impurities such as moisture and foreign substances contained in the fluids. The present invention relates to an impedance detection device for a contaminant filter that allows an operator to easily determine the degree of contaminant capture in the contaminant filter by measuring the impedance of the contaminant filter.

[Background of the Invention] A layer filtration type filter in which the filter element constituting the contaminant filter is formed of a water-absorbing material has the following features: Because it adsorbs moisture, which is the main component of objects,
It is known that this filter is more effective in removing impurities from the fluid to be filtered than a coagulation separation type filter or a sedimentation separation type filter.

Such a contaminant filter is expensive, or the replacement cost of removing it from the flow path in which the contaminant filter is installed is high, so it is difficult to configure the contaminant filter. When the amount of contaminants captured by a filter element reaches a permissible amount, only that filter element is replaced and used.

However, in such a laminar filtration type contaminant filter that adsorbs moisture, since water itself is a low viscosity fluid, the filter element is less likely to become clogged, especially during the process of removing contaminants in the solvent. Therefore, it is not possible to visually confirm the degree of contaminant capture by the contaminant filter, that is, the amount of adsorbed moisture from the outside using, for example, a differential pressure indicator.
Therefore, the filter element is periodically removed from the contaminant filter case and managed by relying on a filtrate check, but this work is extremely complicated.

To solve this problem, it is possible to replace the filter element by monitoring the usage time, but with this method, in some cases, the specified capture amount is still not reached. If you need to replace a filter element that has not been
There is a difficulty in adopting this method because there is a possibility that the filter element will be replaced after the specified amount has been considerably exceeded.

Therefore, in order to eliminate these drawbacks, for example, as disclosed in Utility Model Application No. 59-121580, a layer filtration type filter element is used as a sensor to detect the amount of contaminants captured. A sensor configuration in which a first electrode is disposed close to each other and a second electrode disposed on the filter case side, or a sensor configuration in which a set of electrodes is disposed close to both sides of a filter element. exists. A contamination level detection sensor has been proposed that applies a high-frequency current between the electrodes configured in this way and detects the amount of contaminants captured by the filter element based on the change in dielectric constant caused by the amount of contaminants. ing.

However, since the detection sensor according to such conventional technology has a structure that detects the dielectric constant between the electrodes as a change in the current of the lines of electric force, it detects with high sensitivity in proportion to the amount of contaminants captured by the filter element. The problem is that it is difficult to That is, the detection sensor according to the prior art is basically a capacitance/voltage conversion type sensor, and the drawback is that its applications are extremely limited.

[Object of the Invention] The present invention has been made in order to overcome the above-mentioned disadvantages. 1.1.1 A solvent such as trichloroethane or a fluid such as lubricating oil is filtered to remove water and foreign substances contained in the fluid. When measuring the amount of contaminants captured by a contaminant filter that removes contaminants such as
By arranging the first electrode on the filter element itself constituting the contaminant filter, the second electrode in the flow path, and the third electrode, the ground electrode, in the casing, the filter The change in impedance relative to the amount of contaminants captured by the element is detected proportionally and with high sensitivity, and by converting this into voltage, the amount of contaminants captured by the layer filtration type filter element is monitored.
An object of the present invention is to provide an impedance detection device capable of detecting the lifespan of a contaminant filter element with high cost and performance without missing the time to replace the filter element.

[Means for Achieving the Object] In order to achieve the above object, the present invention provides an impedance detection device for a contaminant removal filter, which includes a filter element in a case in which a flow path is formed, and which comprises: a first electrode located on the fluid discharge side and electrically connected to the filter element that removes impurities from the liquid to be filtered; a third electrode electrically connected to the case and functioning as a ground electrode; impedance between the first and third electrodes and impedance between the second and third electrodes. impedance detection means for detecting the respective impedances, and comparison means for determining the difference between the impedance between the first and third electrodes and the impedance between the second and third electrodes, the impedance being derived from the comparison means. The filter element is characterized in that clogging of the filter element is determined based on a signal related to the difference between the two impedances.

Furthermore, the impedance detection means of the present invention includes:
A high frequency current generating circuit that supplies high frequency current between the first electrode and the third electrode and between the second electrode and the third electrode, respectively, and a voltage corresponding to the impedance between the respective electrodes generated by the high frequency current. The present invention is characterized by comprising an impedance detection circuit for detecting impedance.

Furthermore, the comparison means of the present invention includes a voltage corresponding to the impedance between the first electrode and the third electrode;
The present invention is characterized in that it is a differential amplifier circuit that amplifies the voltage difference between the voltage corresponding to the impedance between the second electrode and the third electrode.

[Embodiments] Next, preferred embodiments of the impedance detection device for a contaminant filter according to the present invention will be listed,
A detailed description will be given below with reference to the accompanying drawings.

FIG. 1 shows a partial vertical cross-sectional configuration diagram of a contaminant filter 10 incorporating an impedance detection device according to the present invention, and the contaminant filter 10 basically consists of a filter element 12, a casing 14, a cover member 16, and an impedance measuring device. It consists of 18. Here, the casing 14 is configured in a cylindrical shape, and one end thereof gradually becomes smaller in diameter to form a funnel-shaped part 14a, which is further closed by a plug 15, and the other end is opened to a larger diameter via a stepped part 14b. A diameter portion 14c is formed. The funnel-shaped part 14a
A cylindrical member 14e having a thread groove inside is integrally formed in the hole 14d.
A rod member 20a is screwed into the thread groove in a substantially flange-shaped filter element holder 20 formed of an insulating material from above in the figure. A plurality of convex protrusions 20c are defined on the flange portion 20b of the filter element holder 20, and the protrusions 20
A filter medium 24 is inserted and fixed into the filter element 12, which is composed of a cylindrical body 22 having a large number of holes 22a and a string-shaped filter medium 24 made of water-absorbing resin. The other end of the filter element 12 is pressed and held from above in the figure by a ring-shaped element electrode 26 having an opening 25. Here, a plurality of electrode protrusions 26b defined on the element electrode 26 are connected to the filter element 1.
The filter medium 24 of No. 2 is charged. The element electrode 26 engages with one end of a connecting pin 28, and one end of an electrode pin 30 is screwed onto the other end of the connecting pin 28. The electrode pin 30 is connected to the impedance measuring device 18 as a first electrode A.

In this case, the electrode pin 30 is insulated from the cover member 16 by a packing 32.

The cover member 16 has an electrode pin 34 constituting a second electrode C insulated by a gasket 32.
One end of the electrode pin 34 is connected to the impedance measuring device 18, and the electrode protrusion 34a provided at the other end connects the passage 38 that communicates with the liquid supply port 36 for the fluid to be filtered. Coming.

A ground electrode E as a third electrode is provided on the cover member 16, and this ground electrode E is connected to the impedance measuring device 18. Furthermore, the cover member 16 has an electrically conductive clamp ring 5.
4, the casing 14, the clamp ring 54, and the cover member 16 are electrically connected and held at the same potential, that is, the ground potential.

On the other hand, gaskets 5 are provided on the step portion 14b of the casing 14 and the upper part of the element electrode 26, respectively.
0 and 52 are interposed, and thereby the cover member 16
The element electrode 26 and the casing 14 are integrated in a liquid-tight manner.

Therefore, the fluid to be filtered is led from the fluid supply port 36 through the passage 38 and further through the opening 25 defined in the element electrode 26 to the internal hollow part 46.
The fluid to be filtered enters the filter medium 24 constituting the filter element 12 from the inner circumference 44 of the filter element 12 through the hole 22 a of the cylindrical body 22 constituting the filter element 12 . The completed passage 43,
A passage 42 leads to an outlet 40 for the fluid to be filtered.

Next, an electric circuit block diagram of the impedance measuring device 18 is shown in FIG. The impedance measurement device 18 basically includes an oscillator 100 that oscillates at a predetermined frequency, and an impedance detection section 102 that detects the impedance Z related to the contaminant filter 10.
and the output signal e ₁ of the impedance detection section 102,
a differential amplification section 104 that differentially amplifies e ₂ ; an analog output section 106 that amplifies and outputs the output signal e ₀ of the differential amplification section 104; a comparison display section 108;
and a power supply unit (not shown) that supplies power to these components.

After the output signal of the operational amplifier IC ₁₄ constituting the oscillator 100 is divided by resistors R ₁₀ and R ₁₂ ,
It is coupled to the impedance detection unit 102 via capacitors C ₁₀ and C ₁₂ , while capacitors C ₁₄ and C _16
The impedance _Z related to the contaminant filter ₁₀ connected in series with _the output signal e ₁ ,
It is converted into e ₂ and introduced. Capacitor C ₁₈ , C ₂₀
The voltage signals e 1 and _{e 2} proportional to the impedance Z introduced into the operational amplifier IC ₁₆ and the operational amplifier IC ₁₈ constituting the differential amplifier section 104 are as follows.
Inverting amplifiers 110 each consisting of an operational amplifier IC ₁₆
and a non-inverting amplifier 112 consisting of an operational amplifier IC ₁₈ , and the output signal _e0 of the differential amplifier 104 consisting of both amplifiers 110 and 112 is introduced into the negative input terminal of an operational amplifier IC ₂₀ constituting the analog output section 106. Ru. In addition, at this time, the operational amplifier
Inverting amplifier 110 consisting of IC ₁₆ and operational amplifier
Resistor forming non-inverting amplifier 112 consisting of IC ₁₈
The same values are selected for R _16a to R _16d .

A variable resistor is connected to the negative input terminal of the operational amplifier IC ₂₀ .
A bias current is supplied from RV ₁₀ and is adjusted so that when the output voltage signal e ₀ of differential amplifier section 104 is 0V, the output voltage of output terminal TB ₁₀ of analog output section 106 is 0V. In addition, the comparison display section 10
A reference voltage V _REF corresponding to the type of fluid to be filtered is supplied to the negative input terminal of the operational amplifier IC ₂₂ constituting the filter 8 via a variable resistor RV ₁₂ , voltage dividing resistors R _22a to R _22c , and a slide switch S ₂₂ . When the output voltage of the operational amplifier IC ₂₀ constituting the analog output section 106 exceeds the reference voltage V _REF , the output voltage of the operational amplifier IC ₂₂ serving as a comparator is inverted, and a current is supplied to the light emitting diode D ₁₆ . Then, the transistor TR ₁₀ becomes conductive, and the transistor TR ₁₀ becomes conductive.
For example, it is configured to stop a control device (not shown) connected to the output terminal TB ₁₂ of the controller.

The impedance filter incorporating the impedance detection device according to the present invention is basically constructed as described above, and its operation and effects will be explained next.

First, impedance measuring device 1 shown in FIG.
The impedance response characteristics of the circuit according to No. 8 will be measured. In this case, a capacitance, which is a discrete element, is connected between the first electrode A and the earth electrode E.
Connect only C _x or resistor R _x . At this time, a predetermined high frequency current from the oscillator 100 is applied to the impedance Z (in this case, the capacitance C _x or the resistance
R _x ) and the peak value of the alternating voltage generated across the impedance Z at the first electrode A is detected by a peak detection circuit consisting of a diode D ₁₀ and a capacitor C ₁₈ to form the differential amplifier section 104. The output voltage signal _e1 is supplied to the positive input terminal of the operational amplifier IC ₁₆ . On the other hand, the peak value on the second electrode C side is detected by a peak detection circuit consisting of a diode D ₁₂ and a capacitor C ₂₀ , and is supplied to the positive input terminal of the operational amplifier IC ₁₈ as a voltage signal e ₂ . In this case, the output voltage signal e ₀ of the differential amplifier section 104 is
Since the values of R _16a to R _16d are selected equally, they are set as shown in the following equation (1).

e ₀ = 2 (e ₂ − e ₁ ) ...(1) This output voltage signal e ₀ is amplified by an amplifier consisting of an operational amplifier IC ₂₀ and sent to the analog output terminal TB _10.
will be introduced in FIG. 3 shows changes in the output voltage V ₁₀ between the output terminals TB ₁₀ measured in this manner.
In Figure 3, the characteristic curve C _x0 is the capacitance
The characteristic curve R _x0 shows the capacitance conversion value c (R _x =1/2πc _x ) of _{the resistance R x .}

As can be easily understood from FIG. 3, according to the impedance detection device according to the present invention, the output voltage can be detected in approximately proportion to the magnitude of the capacitance or resistance. Therefore, for example, when the measured impedances are of the same value,
It can be said that it is possible to always measure the correct impedance even if the phase angle related to the impedance changes.

Therefore, next, we will introduce the impurity filter 1 shown in Fig. 1.
0, as shown in FIG.
The element electrode 26 is placed on the flange portion 20b of the filter element 12, and the convex electrode protrusion 26b of the element electrode 26 attached to the cover member 16 is pressed against the other end of the filter element 12. The filter unit 200 thus formed is screwed into the threaded groove of the cylindrical member 14e formed at the bottom of the casing 14 shown in FIG. At this time, the packing 50 is interposed in the stepped portion 14b of the casing 14.

After forming the contaminant filter 10 in this manner, a predetermined fluid is supplied from the fluid supply port 36.
As fluids 1.1.1 trichloroethane 202, Freon 113, 204, perchlorethylene 206,
When lubricating oil (FBK turbine oil VG32) 208 or the like is introduced from the fluid supply port 36, the fluid flows through the passage 38, the opening 25, the internal hollow part 46, the inner peripheral part 44 of the filter element 12, and the filter element 12 as described above. , the passage 43 and the passage 42 to the discharge port 40, and impurities such as moisture mixed in these fluids are absorbed by the filter medium 24 constituting the filter element 12, and the first electrode A and the earth electrode E the impedance between the filter element 12 in which the element electrode 26 is inserted;
The impedance between the two electrodes is changed, with the casing 14 being one electrode and the casing 14 being the other electrode. The analog output voltage V ₁₀ is determined by the impedance difference between this change in impedance between the filter element 12 and the casing 14 and the impedance between the second electrode C and the ground electrode E, that is, the impedance of the fluid to be filtered before filtration. Change.

FIG. 5 is a diagram showing changes in the analog output voltage V ₁₀ with respect to the amount of water absorbed by each fluid. As can be understood from the figure, it is understood that the amount of water absorbed by the filter element 12 and the output voltage of the impedance measuring device 18 according to the present invention vary depending on each fluid.

The time to replace the filter element 12 is determined by determining the predetermined reference voltage V _REF of the fluid to be filtered, which corresponds to the output voltage related to the predetermined impedance or water absorption amount, from the characteristic curve in FIG.
S ₂₂ is set to the negative input terminal of _the operational amplifier IC ₂₂ of the comparison display section 108 shown in _FIG . If the filter element 12 is replaced by an operator when the light emitting diode D ₁₆ is turned on or when an alarm is sounded, which can be activated by the output of the transistor TR ₁₀ , the filter element 12 can be replaced. It is possible to always exchange a predetermined captured amount. That is,
By using a contaminant filter equipped with an impedance detection device according to the present invention, the amount of water and the degree of contamination in a fluid such as a solvent or lubricating oil can be kept below a certain level, and therefore the contaminant can be cleaned by the fluid. Parts or devices can always maintain quality above a certain level.

[Effects of the Invention] As described above, according to the present invention, 1.1.1 A fluid such as a solvent such as trichloroethane or Freon 113 or a lubricating oil is filtered to remove contaminants such as water and/or metals contained in the fluid. Regarding the electrodes in the filter for removing substances, the first electrode is arranged in the filter element, the second electrode in the flow path, and the third electrode in the case. Therefore, even if the impurity component is not only capacitance but also resistance, it is possible to generate an output voltage proportionally and with high sensitivity, so that correct impedance can be measured.

Furthermore, when the output voltage corresponding to the impedance measured in the comparator exceeds the reference voltage, a light emitting diode is lit to indicate that the amount of water absorbed or the amount of contaminants attached to the filter element has exceeded a certain concentration. Alternatively, by stopping the system that supplies fluid to the contaminant filter, it is possible to achieve the effect that this system can be operated with high efficiency.

Although the present invention has been described above with reference to preferred embodiments, the present invention is not limited to these embodiments, and various improvements and changes in design are possible without departing from the gist of the present invention. Of course.

[Brief explanation of the drawing]

FIG. 1 is a partial cross-sectional configuration explanatory diagram of a contaminant filter incorporating an impedance detection device according to the present invention, FIG. 2 is an electric circuit diagram of the impedance detection device according to the present invention, and FIG. 3 is an impedance detection according to the present invention. FIG. 4 is an explanatory diagram of the impedance detection characteristics of the device. FIG. 4 is a partial cross-sectional configuration diagram of a filter unit in the impedance detection device according to the present invention. FIG. 5 is a diagram showing the water absorption detection characteristics of the impedance detection device according to the present invention. It is an explanatory diagram. DESCRIPTION OF SYMBOLS 10... Contaminant filter, 12... Filter element, 14... Casing, 16... Cover member, 18... Impedance measuring device, 24...
... Filter medium, 30, 34 ... Electrode pin, 36 ... Fluid supply port, 40 ... Discharge port, 100 ... Oscillator, 1
02... Impedance detection section, 104... Differential amplifier section, 106... Analog output section, 108...
Comparison display section, A, C...electrode, E...earth electrode.

Claims (1)

[Scope of Claims] 1. An impedance detection device for a contaminant removal filter comprising a filter element in a case in which a flow path is formed, the impedance detection device being on the discharge side of a fluid to be filtered and detecting contaminants in the liquid to be filtered. a first electrode electrically connected to the filter element that removes substances; a second electrode arranged so as to face the supply passage of the fluid to be filtered; and a second electrode electrically connected to the case. , a third electrode functioning as a ground electrode; impedance detection means for detecting impedance between the first and third electrodes and impedance between the second and third electrodes, respectively; Comparing means for determining the difference between the impedance between the three electrodes and the impedance between the second and third electrodes; An impedance detection device characterized by determining clogging. 2. The device according to claim 1, wherein the impedance detection means is arranged between the first electrode and the third electrode and between the second electrode and the second electrode.
The method includes: a high-frequency current generation circuit that supplies a high-frequency current between the electrode and the third electrode, and an impedance detection circuit that detects a voltage corresponding to the impedance between the respective electrodes generated by the high-frequency current. Characteristic impedance detection device. 3. In the device according to claim 1, the comparison means:
An impedance circuit characterized by being a differential amplifier circuit that amplifies a voltage difference between a voltage corresponding to the impedance between the first electrode and the third electrode and a voltage corresponding to the impedance between the second electrode and the third electrode. Detection device.