JPH0422272Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Industrial Field of Application) The present invention relates to a liquid level gauge whose operation can be easily checked.

(Prior Art) Liquid level gauges are used in storage tanks for liquids such as crude oil and chemicals to detect and measure the level of the liquid. There are various types of liquid level gauges, but from the standpoint of reliability and safety, they are equipped with a guide pipe and a float that can move up and down along the guide pipe. A method that measures the liquid level by electromagnetic detection is widely used.

Hereinafter, an example of the above-mentioned conventional liquid level gauge will be explained with reference to figures showing embodiments of the present invention. In the figure, reference numerals 1, 2, 3, 4, and 5 are capsules, each of which has a reed switch 7 and is attached at regular intervals to a flexible support plate (not shown). The support plate is inserted into a guide pipe (not shown) that is to be vertically installed in a liquid storage tank, so that the reed switches of each capsule are arranged at regular intervals along the inner wall of the guide pipe. ing. A horizontal chain line L is a lower reference line, and a chain line U is an upper reference line.
Capsule 1 has a resistance 8 of 10Ω and an output resistance of 100Ω, capsule 2 has a resistance of 15Ω and an output resistance of 9 and 100Ω, capsule 3 has a resistance of 0Ω and an output resistance of 200Ω, capsule 4 is 0Ω resistance and 68Ω
The capsule 5 has an output resistance of 15Ω and a resistance 9 of 15Ω.
It has an output resistance of 200Ω. Two capsules 4 are arranged below the lower reference line L, and the lower reference line L
One capsule 3 is placed on top of the capsule 3, one capsule 2 is placed on top of the capsule 3, and a large number of capsules 1 are placed on top of the capsule 3 at regular intervals. On the other hand, one capsule 5 is arranged below the upper reference line U, and three capsules 4 are arranged above the upper reference line U. In this way, each capsule 4, 5, arranged at regular intervals from top to bottom,
1, 2, 3, 4 0Ω resistance, 15Ω resistance 9, 10Ω
Resistor 8, 15Ω resistor 9, and 0Ω resistor are connected in series to form a series resistor. Both ends of these series resistors are led outward from the upper end of the guide pipe by lead wires A and C, and a predetermined voltage is applied between the lead wires A and C at both ends.

A float is loosely fitted onto the outer peripheral side of the guide pipe so that it can move up and down while being guided by the guide pipe. A permanent magnet is attached to the inner circumferential side of this float. When the float moves up and down in accordance with the liquid level, the reed switch 7 of the capsule, which faces the magnet of the float across the guide pipe, is actuated by the magnetic field of the magnet and turned on. One end of the reed switch 7 in each capsule 1, 2, 3, 4, 5 is connected to a serial connection point between the resistor in each capsule constituting the series resistor and the resistor in the capsule above it. , the other end of each reed switch 7 is connected to the divided voltage signal output line B via the output resistor. Output line B is also led out from the upper end of the guide pipe.

As mentioned above, when the reed switch 7 corresponding to the float position is turned on, the constant voltage applied between the lead wires A and C at both ends of the series resistor is divided into the voltage corresponding to the float position. A divided voltage signal appears on output line B. Therefore, by measuring the partial voltage appearing on the output line B, the liquid level can be measured. Two or three reed switches 7 adjacent to each other are turned on in response to the float position, thereby increasing the measurement resolution to 1/2 of the capsule installation interval. The area below the lower reference line L and above the upper reference line U is a non-measurement range.

(Problem to be solved by the invention) Reed switches used in conventional liquid level gauges do not require a power source for operation, so they are not suitable for liquid level gauges, which require a large number of them to be placed inside the guide pipe. It is ideal as a sensor, and since the current flowing in a liquid level gauge is minute and there are few opportunities for individual reed switches to operate, it can withstand many years of use and has relatively high operational reliability. .

However, some of the many reed switches become malfunctioning during use. For example, dirt or the like may remain in the tube that encloses the contacts, and if this dirt or the like adheres between the contacts, the contacts may not turn on or may remain on. If even one reed switch malfunctions, the divided voltage will not be output accurately and the liquid level will not be measured.
You need to check whether the reed switch is working properly.

In conventional liquid level gauges, when checking for malfunctions, the support plate supporting each capsule was pulled out from the guide pipe, and the operation of the reed switches in each capsule was checked one by one. However, it takes a lot of time to check a large number of reed switches one by one. In particular, ships such as tankers need to be checked and repaired during the limited time they are moored at a port, but unlike conventional liquid level gauges, it is necessary to check and repair many reed switches one by one. In some cases, it was not possible to make it in time.

The present invention was made to solve such conventional problems, and when a reed switch malfunctions, it is possible to estimate the position of the reed switch causing the malfunction, and to redirect the reed switch. It is an object of the present invention to provide a liquid level gauge that allows quick checking and repair of a switch.

(Means for solving the problem) The present invention provides test lead wires to the output ends of reed switches selected at regular intervals among a large number of reed switches arranged at regular intervals in the guide pipe. The lead wire is connected to the guide pipe and the lead wire is drawn out of the guide pipe.

(Function) One reed switch malfunctions and does not turn on.
Or, if it remains off, the partial pressure value appearing on the test lead wire where the reed switch is located will fluctuate more rapidly than the normal step, so the reed switch in the range defined by the test lead wire will It can be assumed that a malfunction has occurred.

(Example) Hereinafter, an example of the liquid level gauge according to the present invention will be explained with reference to the drawings, but since the basic configuration of the liquid level meter is as described above, here we will explain improvements to the above basic configuration. We will focus on explaining the features of the present invention, including the following.

In the figure, test lead wires L1 and L are connected to the output ends of reed switches 7 selected at regular intervals, for example, every 1 m, from among a large number of reed switches 7 arranged at regular intervals in the guide pipe.
2,...Ln, Ln-1 are connected. Each of these lead wires is drawn out of the guide pipe.

According to the above embodiment, a large number of reed switches 7
If one of the reed switches malfunctions and does not turn on or even turns off, the partial pressure value appearing on the test lead wire corresponding to the group to which that reed switch belongs changes more rapidly than in a normal step. Therefore, by checking a test lead wire whose partial pressure value changes rapidly, it is possible to infer that there is an abnormality in the reed switch within the range defined by the test lead wire. By intensively checking the reed switch, quick checks and repairs can be carried out.

In addition, the test lead wires L1, L2,...Ln,
A clock may be connected to Ln-1 for constant monitoring, or a meter may be connected to Ln-1 for monitoring only when checking the operation.

(Effects of the invention) According to the invention, test lead wires are connected to the output ends of reed switches selected at regular intervals among a large number of reed switches and are pulled out of the guide pipe. You can check the operation of each group of reed switches separated by test lead wires, and if there is an abnormality, you can concentrate on checking the reed switches in that group, allowing for quick checks and repairs. can.

[Brief explanation of the drawing]

The figure is a circuit diagram showing an embodiment of the liquid level gauge according to the present invention. 7...Reed switch, 8, 9...Series resistance,
L1, L2, Ln, Ln-1...Test lead wires.

Claims (1)

[Claim for Utility Model Registration] A guide pipe to be vertically installed in a liquid storage tank, a float that can move up and down guided by the guide pipe and has a permanent magnet, and a large number of floats having a predetermined resistance value. a series resistor made of a resistor, which is connected in series within the guide pipe and to which a predetermined voltage is applied between both ends of the series connection; A number of reed switches are connected to each connection point of the series resistors, and are actuated by the magnetic field of the magnets when the float magnets face each other across the guide pipe, and output a divided voltage signal due to the series resistors at that time. In the liquid level gauge having the above-mentioned large number of reed switches, a test lead wire is connected to the output end of the reed switch selected at regular intervals, and this lead wire is pulled out of the above-mentioned guide pipe. A liquid level gauge characterized by: