JP2579259B2 - Protective anode and cathodic protection system - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a protective anode and cathodic protection system for preventing oxidation of metals in an oxidizing environment.

[0002]

2. Description of the Related Art When various metals come into contact with an electrolyte such as salt water or industrial contaminants, the metals dissolve in the surrounding electrolyte and oxidize or corrode. Such corrosion is directly attributable to the current generated by the reaction between the metal surface and the contained chemicals. The second form of corrosion is called galvanic corrosion, and galvanic corrosion occurs when different metals are placed in the electrolyte. The high potential metal becomes the anode and the low potential metal becomes the cathode.

[0003] In the prior art, methods have been sought to sufficiently prevent the oxidation of target metals exposed to oxidizing environments. However, it has been found that conventional methods and devices do not provide satisfactory results. In the prior art, there are various cathodic protection systems. The system protects the target metal from corrosion by using the metal to be protected as the cathode of an electrolysis circuit. The above method generally requires an anode, an electric energy source and an aqueous solution. The anode and cathode are immersed in an aqueous solution. A current is then created between the anode and cathode using an electrical energy source.
When electrons are supplied to the cathode from an electrical energy source, the material to be reduced in the aqueous solution is reduced by gaining electrons from the current rather than the electrons of the metal. The electrons required for the reduction of the chemicals in the aqueous solution are generally supplied from the current rather than from the cathode metal, so that the oxidation rate of the cathode is extremely low.

US Pat. No. 3,242,064
Discloses a cathodic protection system in which a pulse of direct current is applied to the surface of the metal to be protected. U.S. Pat. No. 3,692,650 shows a cathodic protection system utilizing short-wave DC voltage and continuous DC current. The frequency of the voltage pulse is a frequency that is sufficient to convert the acid ions and that does not cause an undesirable chemical reaction. U.S. Pat. No. 4,915,808 discloses opposed first and second planes.
Shown are anodes whose planes are connected by rectangular side walls. The insulation is stripped from the distal end of the lead and the end is inserted through the side wall. A wire protruding from the opening on the second surface of the anode is wound around the opening. Further, an adhesive surface is formed on the flange surface and the first surface of the anode at the center thereof.

US Pat. No. 4,767,512
Discloses a method for preventing oxidation of a target metal by capacitive coupling. Current is passed through the metal. A pulse of direct current is supplied to the anode plate. The target metal is grounded to the pulse supply means. United States Patent 4,955
No. 0,372 discloses a humidity-sensitive cathodic protection device in which a direct current is supplied to an integrated circuit type time power controller and the controller outputs clock pulses. A capacitor for charging the output connects the power source and the timer to the vehicle body. U.S. Pat. No. 4,855,027 discloses a protective anode composed of carbon, silica gel, and an inert adhesive. The anode may be attached to the surface by an adhesive, or may be separated from the surface by an insulating layer.

US Pat. No. 4,828,665
No. 1 shows a cathodic protection system for an automobile body in which a positive electrode is loaded with a capacitive charge. The charge is spread by the moisture on the painted surface. United States Patent No. 4,64
No. 7,353 shows an anode device for an automotive cathodic protection device, which comprises a layer extending on a metal element surface having a through hole for accommodating a fastener, and an anode mounted on the layer. And an anode made of carbon and having a through hole for accommodating the fastener. A wire is mounted on a plastic threaded fastener that penetrates the anode and the hole, and the anode with the wire is secured to the surface. U.S. Pat. No. 4,504,375 shows an anode element for use in a cathodic protection system with a tube having front and rear cusps effective against impact. The tube is filled with a material containing particulate carbon, in which a metal rod is housed.

US Pat. No. 4,921,588
No. 2 shows a method of mounting an anode on a vehicle body for a cathodic protection device for automobiles, the method comprising an acid-washed painted metal surface, an anode made of carbon, silica gel, and an inert adhesive, It has an anode in which a hole is formed and an electric wire centered in the hole is arranged, the electric wire is held in contact with the anode, and a carbon anode is arranged and adhered on a painted metal surface.

[0008]

In the prior art cathodic protection system, oxidation of the target metal could not be effectively prevented in a reliable process at a low cost.

[0009]

SUMMARY OF THE INVENTION The present invention is directed to a protective anode and cathodic protection system that prevents oxidation of metals in an oxidizing environment.

[0010] The protective anode includes a sacrificial anode body made of metal and means for controlling the anode current. The anode current control means has a pair of transistors, a porous humidity sensitive element, a light emitting diode, and a probe or ground. The anode current control means is connected to the power supply and supplies a current to the metal via the ground. The protective anode further includes means for attaching the protective anode to the metal to be protected. Since the porous humidity-sensitive element is exposed to the surroundings, an electric current is supplied to the metallic sacrificial anode body in proportion to the humidity.

The cathodic protection system may include a power supply means, a controller, and an anode control means, and the power supply means may be connected to a power supply to reduce the voltage and rectify the AC voltage to a DC voltage. The operation of the system may be sequentially controlled, and a controller may be connected to the display means to display an operation state signal of the system, and the anode control means may be connected to the protection anode to control the current supply to the protection anode.

[0012]

The protective anode is mounted on the metal to be protected and the protective anode is connected to a power source through a cathodic protection system. The cathodic protection system controls the current and voltage supplied to the protective anode, electrodes the protective anode and displays the operating status, thereby controlling and monitoring the operation and sequential operation of the individual protective anodes.

The present invention includes the following structural features, element combinations, and component arrangements, and the summary of the invention is set forth in the appended claims.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The characteristics and embodiments of the present invention will be described below in more detail with reference to the accompanying drawings. In the drawings, the same members are denoted by the same reference numerals.

The present invention relates to a cathodic protection system indicated by reference numeral 12 in FIG. 1 and a protective anode indicated by reference numeral 11 in FIGS. 2 to 4 for preventing oxidation of a metal in an oxidizing environment described later. Cathodic protection system 12
Has a plurality of components and sub-components, as shown in FIGS. 5 to 11, and is housed in a controller housing 14 in the cathodic protection system shown in FIG.

When the metal is immersed in the electrolyte, the metal has a destructive power. This force causes the metal to dissolve in the surrounding electrolyte, after which the metal generally combines with oxygen, forming an oxide or rust corrosive. This phenomenon is considered to be the effect of returning the metal to the most stable state. Corrosion is the continuation of an electrochemical process that destroys metals. This corrosion is due to currents generated by reactions between metal surfaces and chemicals present on or around the car body.

A second type of corrosion is called galvanic corrosion, which occurs when a dissimilar metal is immersed in an electrolytic solution. Among the dissimilar metals, a metal having a high potential serves as an anode, and a metal having a low potential serves as a cathode. Such a corrosion battery repels high potential metal ions until they are exhausted. In general, the metals that make up a corrosion battery are grouped according to an electrochemical sequence and a potential sequence. From the active metal side to the noble metal side, in other words, the inactive metal side, magnesium, aluminum, iron (first
Iron), cadmium, nickel, tin, brass, copper,
There are silver, monel, titanium, platinum, graphite, and gold. When dissimilar metals are immersed in the same electrolyte, higher metals in the electrochemical and potential trains are sacrificed by lower metals. This sacrificial collapse is the principle of cathodic protection.

As another method of suppressing metal corrosion, there is a method of reversing the direction of galvanic current in a corrosion cell by an external current. That is, when a direct current is applied to the anode made of platinum, graphite, cast iron, aluminum, and other economically advantageous materials, the galvanic current flows backward from the steel, the steel becomes a protective cathode, and metal corrosion is suppressed. You.

The cathode device suppresses corrosion or rust by applying a direct current from the integrated circuit to or around the metal structure. The DC current may be either a DC current from a DC storage battery or a rectified AC current, and can prevent a collapse process of the metal structure due to salt or the like in the air on the road. As best shown in FIGS. 2 and 3, the protective anode 10 comprises a metallic sacrificial anode body 16.
The main body 16 has a concave portion 18 and a groove 20 for accommodating the anode current control means 22. As shown in FIGS. 2 to 4, the anode current control means 22 includes a first transistor 24, a second transistor 26, a porous humidity sensitive element or resistor 28, a resistor 30,
It has a light emitting diode (LED) 32 and a probe (ground) 34 extending from the LED 32, at least a part of the LED 32 is accommodated in the recess 18, and the probe 34 extends along the groove 20. The anode current control means 22 is connected to a power supply (not shown) via an anode lead 36 and an anode connector 38. The protective anode 10 includes a double-sided adhesive 40 and can be bonded to the metal A to be protected.

The hole 42 is formed by penetrating the sacrificial anode body 16 and the double-sided adhesive 40, and the fastener 44 is accommodated in the hole 42 and the hole 46 formed in the metal A corresponding to the hole 42. Thus, the protection anode 10 may be fixed to the metal A to be protected. The porous humidity sensitive element 2
8 is exposed to the surroundings, and a current proportional to the environmental humidity is supplied to the metal body 16 of the sacrificial anode.

FIG. 5 is a block diagram of the components of the cathodic protection system. The cathodic protection system includes a power supply means 48, which is connected to a power supply (not shown) via a wire 50, a system control means 52, and an anode control means 58, the control means 52 comprising: The anode control means 58 is connected to a display means (indicated by reference numeral 54 in FIG. 1) via a connection means 56, and as shown in FIG. Connected through.

As shown in FIG. 1, each protective anode 10 may be directly connected to anode control means 58 by a respective output lead 60. Alternatively, as shown in FIG.
8 may be connected to a plurality of protective anodes 10 by a single output conductor 60. As will be described later, the cathodic protection system is also operable with a power source (not shown) of either an AC source or a DC source.

FIG. 10 is a circuit diagram of the system control means 52. The system control means 52 includes a voltage control means and a display adjustment means, and a DC power supply (not shown) of the voltage control means and the display adjustment means has a voltage of 12V or 24V. It is a DC storage battery or the like. The system control means 52 is connected to a power supply via an input terminal 64. The voltage control means has an amplifier 66 and an oscillator 68, and controls the voltage to a value between 11.2 V and 14 V and outputs it to the anode control means 58 via the control panel 120 and the lead 72. The display means 74 has a light emitting diode, and has a DC power supply (not shown).
The DC power supplied to the system control means 52 from is displayed.

The system control means 52 includes a series resistor 76,
78, a diode 80, series resistors 82, 84, a Zener diode 86 and resistors 88, 90, 92,
And a capacitor 94, which is connected to the first amplifier 66 and the second amplifier 68. The system control means 52 also includes a resistor 96, a series diode 98,
100, a resistor 102 and a capacitor 104 coupled in parallel, parallel resistors 106 and 108, a capacitor 110 and a Zener diode 112 coupled in parallel,
It includes parallel capacitors 114 and 116 and a resistor 118. The output terminal has a control panel 120 and a connector 122.

FIG. 11 is a circuit diagram of the anode control means 58 for a DC power supply (not shown). The anode control means 58 has a plurality of anode channels indicated by reference numeral 130, and each channel 130 corresponds to each protective anode 10. One end of each anode channel 130 is connected to the system controller 52 by a wire 72 with a current controller 132 and a parallel resistor 134,
The other end is connected to the ground via a conductor 140. Each anode channel 130 includes a zener diode 142 and a resistor 144, respectively, which are coupled to a transistor 148 and a resistor 150 in parallel with a plurality of diodes 146. The base 152 is connected to a light emitting diode (LE) through a resistor 156.
D) connected to 154 to indicate the output to each protective anode 10 via the corresponding conductor 60.

FIGS. 7 to 9 show a power supply (not shown) such as a 110 V AC power supply or a 220 V AC power supply.
The circuit of the cathodic protection system for application to the invention is shown. In particular, FIG. 7 is a circuit diagram of the power supply means 48 for lowering the operating voltage and rectifying the alternating current to the direct current. The power supply means 48 is connected to an AC power supply (not shown) through a two-position type double throw switch 160 and a fuse 162, and the switch 160 and the fuse 162 alternately reduce a 110 / 220V AC to 16V. 164 is connected to the input terminal. An output terminal of the transformer 166 is connected to a rectifier diode array 168 that rectifies an alternating current into a direct current. The output from the rectifier diode array 168 is sent to each of the capacitors 170, 172, 174 and the integrated circuit controller 176,
The integrated circuit 17 operates at a reduced operating voltage, for example, 5 V.
8 is fed. As other circuit components, the controller 176 includes a series resistor 180, 182, a parallel capacitor 184, 186, a diode 188, and a diode 19.
0 and a capacitor 192 are included.

FIG. 9 is a block diagram of the system control means 52 and the display means 54 to be applied to an AC power supply. The system control means 52 is connected to the multiplex transmission means 202 and the first
Clock encoder 2 connected between clock phase inverter 204
00. The multiplex transmission means 202 includes a code 206
, A second multiplex transmitter 208, and a second clocked phase inverter. The output of the multiplex transmission means is sent to the analog-to-digital converter 212, where the analog signal is converted to a digital signal. Display means 54
Are a plurality of digital excitation means (indicated by reference numeral 214) for inputting a digital signal from the analog-to-digital converter 212, and a plurality of resistor banks (indicated by reference numeral 2) corresponding thereto.
16) and a plurality of light emitting diodes (LEDs, indicated by reference numeral 218), the display means 54 also includes a sequential control means 220 for the channel connected to the output end of the clock encoder 200, It has a device bank 222 and a pair of light emitting diodes (LEDs, indicated by reference numeral 224).

FIG. 8 shows an anode control means 58 for application to a 100 V or 220 V AC power supply (not shown).
FIG. The anode control means 58 has a plurality of anode channels (the entire anode channels are indicated by reference numerals 230), and each anode channel 230 corresponds to the same number of the protective anodes 10. Each anode channel includes a current controller 232 connected to the power supply 48 via a diode 234, which controls the DC current to a maximum value of 30.
Limit to 0 mA. The output of each current controller 232 is sent to a corresponding protective anode 10 and current monitor 236 via a plurality of resistors (indicated by reference numeral 238). Each current monitoring device 236 is connected to the system control unit 5
2 and display means 54. Or, FIG.
As shown in (1), current may flow through a plurality of protective anodes 10 via a single anode channel 230. In this example, a circuit controller 232 is mounted on each protective anode 10.

When operating this embodiment, one or more protective anodes 10 are mounted on the metal A to be protected and
0 is connected to an AC or DC power supply (not shown) via a cathodic protection system. The cathodic protection system limits the current and voltage sent to the protective anode,
Are turned into electrodes and the operating state is displayed on the display means 54. In this way, the cathodic protection system comprises the protective anode 1
0 is controlled and monitored.

It is clear from the above description that the object of the present invention is achieved. Moreover, the above description and accompanying drawings merely illustrate the present invention and show one interpretation thereof,
It is clear that various modifications are possible from the summary of the present invention. That is, the present invention is not limited to the above embodiments, and the present invention is not limited to the expression forms and terms of the above description, and claims the overall configuration, features, etc. of the technical ideas indicated by the claims. Range.

[0031]

According to the present invention, a highly reliable protective anode and cathodic protection system is provided, and effects such as reliable prevention of metal oxidation or corrosion can be obtained at low cost.

[Brief description of the drawings]

FIG. 1 is a perspective view of a control housing of a cathodic protection system.

FIG. 2 is a perspective view of a protective anode.

FIG. 3 is a side sectional view of a protective anode.

FIG. 4 is a circuit diagram of a protective anode.

FIG. 5 is a block diagram of a cathodic protection system.

FIG. 6 is a schematic diagram of another embodiment of the protective anode circuit.

FIG. 7 is a circuit diagram of a power supply unit.

FIG. 8 is a circuit diagram of an anode control means for an AC power supply.

FIG. 9 is a block diagram of a system control means for an AC power supply.

FIG. 10 is a circuit diagram of a system control means for a DC power supply.

FIG. 11 is a circuit diagram of an anode control means for a DC power supply.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 Protective anode 12 Cathodic protection system 14 Housing 16 Sacrificial anode main body 22 Anode current control means 48 Power supply means 52 Control means 54 Display means 58 Anode control means

Claims (10)

(57) [Claims] 1. A protective anode for applying a current to a metal article from an external power supply to prevent oxidation of the metal article, controlling a sacrificial anode body of metal mounted on the metal article, and controlling a current to the metal article. Current control means for the anode, the current control means comprising a porous humidity sensitive element connected to an external power supply. 2. The device of claim 1, wherein the porous humidity sensitive element comprises a resistor partially exposed to the environment, the resistor being configured to pass a current having a value directly proportional to the environmental humidity to the metal article. The protective anode according to 1. 3. The device according to claim 2, wherein the anode current control means includes a light emitting diode connected to the resistor and the metal article, for visually displaying a current supplied to the metal article. Protective anode. 4. The anode current control means includes a current limiter connected to the external power supply and the metal article for limiting a maximum amount of current flowing to the metal article.
The protective anode according to 1. 5. The protective anode according to claim 4, further comprising a ground probe extending between the light emitting diode and the metal article. 6. The protective anode according to claim 5, wherein said anode current control means includes a pair of transistors connected to said current limiter and said resistor. 7. The protective anode according to claim 6, wherein the metal sacrificial anode includes a recess in which a part of the anode current control unit is accommodated. 8. The protective anode according to claim 1, further comprising mounting means for bringing the metal sacrificial anode body into contact with the metal article. 9. The mounting means having an adhesive surface.
The protective anode according to 1. 10. The protective anode according to claim 8, wherein the mounting means has a hole formed in the metal sacrificial anode body and through which a fastener is passed.