JPH0147552B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a cathodic protection device for hull outer plates and propulsion blades.

BACKGROUND OF THE INVENTION Conventionally, for the purpose of preventing corrosion of hull outer plates and propulsion blades that are in contact with seawater, a cathodic protection device as shown in FIG. 1, for example, has been used.

This conventional cathodic protection device includes an insoluble anode 2 provided on a hull outer panel 1, a reference electrode 3, and a reference electrode 3 provided inside the ship. A DC power supply device 4 that supplies a required current from an output terminal 4b to an insoluble anode 2 based on the comparison with a set value through It consists of a ground circuit 5 and a ground circuit 8 between the shaft 7 of the propulsion blade 6 and the hull outer plate 1.

By the way, in this cathodic protection device, the corrosion protection status of the hull outer plate 1 is detected by the reference electrode 3, this detection signal is compared with the set value of the DC power supply device 4, and the DC power supply is adjusted based on the comparison calculation value. Since this is so-called automatically controlled cathodic protection in which a required current is supplied from the device 4 to the insoluble anode 2, the corrosion protection current flowing to the hull outer plate 1 can be controlled, but the corrosion protection current flowing to the propulsion blades 6 cannot be controlled.

Therefore, when the anti-corrosion current for the hull outer plate 1 is reduced by automatic control, the anti-corrosion current for the propulsion blades 6 is also reduced at the same time, resulting in insufficient corrosion protection of the propulsion blades 6.

The present invention enables the corrosion protection current for the propulsion blades 6 to be independently controlled so that the propulsion blades 6 can be properly protected against corrosion at all times.

An example of the implementation of the present invention will be explained below based on FIG. 2.

As shown in FIG. 2, the anti-corrosion current feedback input end 4c of the DC power supply device 4 is connected to the grounding circuit 8 between the shaft 7 of the propulsion blade 6 and the hull outer plate 1, and the input end 4c is connected A variable resistance element 9 is provided in the ground circuit 8 which is located closer to the hull outer plate 1 than the point.

This variable resistance element 9 controls the feedback anti-corrosion sulfur from the hull outer plate 1 to the anti-corrosion current feedback input terminal 4c of the DC power supply 4, and controls the anti-corrosion current to the hull outer plate 1 by the automatic control described above. When the corrosion protection current for the propulsion blades 6 decreases due to
By increasing the low resistance value of to a required value and suppressing the return anti-corrosion current from the hull shell plate 1 to the anti-corrosion current feedback input terminal 4c of the DC power supply 4, the anti-corrosion current from the insoluble anode 2 is reduced. It is possible to return the anti-corrosion current to the anti-corrosion current feedback input terminal 4C of the DC power supply device 4 via the propulsion blades 6 and the shaft 7, thereby increasing the anti-corrosion current to the propulsion blades 6 to a required value.

Figure 3 shows a conventional cathodic protection device (Figure 1),
Comparative measurement data of the corrosion protection current value for the propulsion blade 6 using the cathodic protection device of the present invention (FIG. 2) is shown.

As is clear from FIG. 3, in the conventional cathodic protection device, it is not possible to control the corrosion protection current to the propulsion blade 6, and the value is only about 7 to 7.5 A, but according to the cathodic protection device of the present invention, By changing the low resistance value of the variable resistance element 9, the corrosion protection current value for the propulsion blade 6 can be controlled over a range of 7 to 16 A.

Note that it is preferable that the variable resistance element 9 be automatically controlled by, for example, a corrosion protection current detection circuit for the propulsion blade 6.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram of a conventional cathodic protection device, Fig. 2 is an explanatory diagram of the cathodic protection device of the present invention, and Fig. 3 is comparative measurement data of corrosion protection current values for propulsion blades between the conventional device and the device of the present invention. It is.

Claims (1)

[Claims] 1 Corrosion protection current feedback input terminal of the DC power supply device that compares the corrosion protection status detection signal from the reference electrode provided on the hull outer panel with a set value and supplies the required current to the insoluble anode provided on the hull outer panel. is connected to the ground circuit between the shaft of the propulsion wing and the hull shell, and a variable resistance element is installed in the ground circuit that is closer to the hull shell than the connection point of this input end. Cathodic protection equipment.