JPH0428026Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Field of Application of the Invention] The present invention is directed to muddy soil, and in particular relates to a muddy soil level detector that is excellent in detecting the level of low moisture content muddy soil.

[Background of the idea]

In recent years, a pneumatic dredging system as shown in FIG. 2 has been developed as a system for dredging mud such as sludge deposited on the bottom of small and medium-sized rivers, inland lakes, and the like.

In this system, mud pumping tanks 2 having a pressure vessel structure are arranged in parallel on a barge 1, and a hopper 3 with mud collection screws 3a arranged in parallel at the bottom is installed above both mud pumping tanks 2. A bucket hoe (not shown) mounted on the hopper 1 excavates the soil and pours the mud into the hopper 3 from above. The mud collection screws 3a provided at the top of both tanks 2 and at the bottom of the hopper 3 are connected by remote-controlled, air-driven, etc. mud charging on-off valves 4, which alternately feed the mud from the hopper 3. In order to supply mud into the tank 2, the on-off valve 4 for introducing mud is alternately opened and closed.

On the other hand, both tanks 2 are connected to a mud feeding pipe 6 extending to a remote location via remotely controlled air-driven mud discharge valves 5, respectively, and both tanks 2 are connected to a compressed air source (not shown). For example, when the mud supplied to one of the tanks 2 reaches a predetermined amount, the mud charging valve 4 of the tank 2 is closed, and , the mud discharge valve 5 and the air valve 7 are opened, and the compressed air supplied to one tank 2 forces the mud in the tank through the mud pipe 6 to a remote location, while the mud discharge valve of the other tank 2 is opened. 5 and the air valve 7 are closed, and the mud feeding on/off valve 4 is opened to supply the mud from the hopper 3 into the tank 2, and by performing these operations alternately, the mud can be continuously pumped. ing.

The dredging system configured in this way excavates the mud deposited on the bottom of the water using a backhoe, and uses compressed air via the mud pumping tank 2 to transport the mud into the mud pipe without causing secondary pollution such as bad odors while keeping the water content low. It has the advantage of being able to be sent under pressure to remote locations.

By the way, in such a dredging system,
Opening/closing operation of the mud input on-off valve 4 for alternately supplying mud from the hopper 3 into the two tanks 2, and a mud discharge valve for alternately pressure-feeding the mud from the two tanks 2 to the mud feeding pipe 6. The opening/closing operations of the air valves 5 and 6 are controlled using a timer, and the timer is set for a storage time corresponding to a predetermined amount of mud being stored in one of the tanks 2. The opening degree of the mud discharge valve 5 is adjusted in advance so that all the mud in the tank can be pumped out in a time approximately equal to this storage time, and mud is stored and pumped alternately in the cycle of this storage time. There is.

However, the time it takes for the mud supplied from the hopper 3 to the tank 2 to reach the specified storage volume may vary depending on conditions such as moisture content and viscosity, so if the dredging location changes, the timer setting time may vary. It was necessary to change.

Therefore, a level detector has been proposed that uses the conductivity of the mud by extending a level detection rod to a predetermined level position of the mud, but the mud in the tank 2 is always scattered during supply and discharge. Because it is in a state of
There was a problem with mud adhering to the level detection rod, causing it to malfunction.

[Purpose of invention]

The present invention was made to solve these conventional problems, and is a mud level detector that can detect the mud level without mud adhering to the level detection rod. The purpose is to provide the following.

[Summary of the idea]

The gist of the present invention to achieve the purpose of the present invention is to include a level detection rod having conductivity, and a sensor fixed to the upper end of the level detection rod and formed coaxially with the level detection rod. an insulator made of a non-conductive member having a groove with a downward opening, and a pair of high-pressure air pipes that communicate with the groove and are disposed opposite each other in a radial direction; The mud level detector is characterized in that by supplying high-pressure air to the high-pressure air pipe, a unidirectional high-pressure air flow around an axis is formed in the groove and ejected downward.

[Example of idea]

The present invention will be explained in detail below based on the embodiment shown in FIG.

Reference numeral 10 denotes a level detection rod made of a conductive material, and an insulator 11 having a planar circular shape made of a non-conductive material such as synthetic resin is fixed concentrically to the upper end thereof. 1
Reference numeral 2 designates a tank mounting flange which is fixed via bolts to a level detector mounting hole 2a drilled at the top of the mud pumping tank 2, and an insulator 11 is fixed inside.

The level detection rod 10 has its lower end extended to the detection level of mud in the tank 2.
A lead wire 13 connected to a terminal 10a provided at the upper end of the 0 is connected to a level detection device 14. Further, this level detection device 14 is grounded to the tank 2 so that it has the same potential as the mud in the tank 2. When the level detector of this embodiment is used for high level detection, when the mud supplied into the tank 2 reaches a position where it touches the lower end of the level detection rod 10, the level detection device 14 An on signal is output to a valve opening/closing control device (not shown) to notify that mud has been supplied to a predetermined level in the tank 2.

In addition, when used as a low level detector, when the top surface of the mud drops below the lower end of the level detection rod 10 due to discharge of mud in the tank 2, the level detection device 14
outputs an off signal to the valve opening/closing control device to notify that the mud in the tank 2 has been discharged.

On the other hand, the insulator 11 has a level detection rod 1 at its lower end.
A concave groove 15 is formed to surround the concave groove 15, and two air pipes 16 and 17 are inserted into the upper end of the concave groove 15 so as to face each other and are inserted through the tank mounting flange 12 along the tangent line of the concave groove 15. However, high pressure air is blown into the groove 15 through the air pipes 16 and 17.

That is, mud is always scattered inside the mud pumping tank 2 during supply and discharge of mud, and the scattered mud adheres to the level detection rod 10.
If it becomes large enough to reach the inner wall surface of the tank 2, it will become conductive and cause malfunction, but by blowing high-pressure air into the groove 15 from the air pipes 16 and 17, the high-pressure air will flow downward from the groove 15. The level detecting rod 10 is cleaned by blowing off mud adhering to the level detecting rod 10. At that time, from the air pipes 16 and 17 to the groove 15
Since the high-pressure air blown into the groove 15 is blown in the same direction along the tangential direction of the groove 15, the high-pressure air blown downward from the groove 15 is detected by the level detection rod 1.
The flow becomes a swirl around 0, and the level detection rod 10
The mud adhering to the surrounding area can be blown away efficiently.

In this embodiment, the level detection rod 10 is cleaned with high-pressure air in order not to impair the advantages of the pneumatic dredging system, which pumps mud with a low moisture content. When cleaning the level detection rod 10, cleaning water accumulates in the tank 2, which increases the moisture content of the mud, so a method of cleaning the level detection rod 10 using water is not adopted. be.

[Effect of idea]

As explained above, according to the present invention, by swirling high-pressure air around the bare level detection rod, it is possible to efficiently remove low-moisture mud stuck to the level detection rod. It can be blown away well for cleaning, and the level of mud can be accurately detected without false positives.In addition, in pneumatic dredging systems that use compressed air to transport the mud stored in the tank, the mud in the tank can be If used to detect the level, the level detection rod is cleaned with high-pressure air, so it does not affect the moisture content of the mud being pumped, and it can be pumped with a low moisture content. If you can, you will get the desired effect.

[Brief explanation of the drawing]

Fig. 1 shows an embodiment of the mud level detector according to the present invention, Fig. 1A is a longitudinal sectional view, Fig. 1B is a sectional view taken along the line A-A, and Fig. 2 is a pneumatic feed type. The dredging system is shown, with FIG. 2A being a front view, FIG. 2B being a plan view, and FIG. 2C being a side view. 10... Level detection rod, 11... Insulator, 12
... Tank mounting flange, 13 ... Lead wire, 1
4...Level detection device, 15...Concave groove, 16,1
7...Air pipe.

Claims (1)

[Scope of utility model registration request] A conductive level detection rod and a non-conductive member fixed to the upper end of the level detection rod and having a groove with a downward opening formed coaxially with the level detection rod. and a pair of high-pressure air pipes that communicate with the groove and are disposed at opposite positions in the radial direction. A mud level detector that is characterized by forming a high-pressure air flow in one direction around an axis and ejecting it downward.