JPH0634664Y2 - Differential pressure indicator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial application] For example, a differential pressure indicator such as a differential pressure indicator or a differential pressure relay is used to monitor gas leakage in the outer box of a dry transformer.

This invention relates to the differential pressure indicating device.

[Prior Art] FIG. 2 shows an example thereof.

10 is a tank and 12 is a gas filled therein.

Reference numeral 14 denotes a temperature-sensing part, which is composed of a hermetically sealed container, is inserted into the tank 10, and has the same temperature change as the gas 12.

16 is the first bellows and 18 is the displacement part.

The bellows 16 communicates with the temperature sensing portion 14 through a pipe 20, and the gas 12 in the tank 10 enters the communicating internal space.
A gas 22 of the same type and of equal density is enclosed.

Reference numeral 24 is a second bellows, and the area of its displacement portion 26 is equal to that of the bellows 16.

The bellows 24 and the tank 10 are connected by a pipe 28.

The bellows 16 and the displacement portion 26 are connected by a rod 30.

32 is a guideline and 34 is its fulcrum. Pin the middle to rod 30
36.

38 is a case, 40 is the whole apparatus.

-Operation: (1) As a general rule, the temperature of the gas 22 in the bellows 16 and the temperature of the gas 12 in the bellows 24 are equal.

Therefore, the force f ₁ which gas 22 pushes the rod 30 through the bellows 16, equal to the force f ₂ to press the rod 30 gas 12 through the displacement portion 26, and a reverse direction.

Therefore, the pointer 32 does not move.

(2) The above relationship does not change even if the temperature of the gas 12 changes.

(3) If there is a hole in tank 10 and gas 12 leaks, gas 12
Pressure drops.

Then, f ₁ > f ₂ , and the pointer 32 rotates clockwise to notify the abnormality. Also, in the case of relays, the contacts are opened and closed.

[Problems to be solved by the invention] In this type, generally, the two bellows 16 and 24 are put in the case 38 as described above, and the pipe is taken out from the case 38 and attached to the tank 10 side. There is.

Therefore, a temperature difference may occur around the tank 10 and the case 38.

Then, the forces f ₁ and f ₂ actually applied to the rod 30 are as follows.

However, ・ V ₁ : volume of temperature sensing part 14, ・ V ₂ : volume of tank 10, ・ v ₁ : volume of bellows 16, ・ v ₂ : volume of bellows 24, ・ P ₁ : pressure of temperature sensing part 14 , · P _2: pressure of the tank 10, · p _1: the pressure of the bellows 16, · p _2: pressure of the bellows 24, the second bellows 24, since V ₂ is very large compared to v _2, of the It is hardly affected by the temperature difference.

On the other hand, in the first bellows 16, V ₁ cannot be increased so much that an error occurs due to the pressure difference based on the temperature difference (usually the temperature on the tank 10 side is high, so the pressure on the second bellows 24 side is Will be higher).

[Means for Solving Problems] As shown in FIG. 1, (1) a case 42 is directly connected to and communicates with the tank 10, and an actuator (bellows 16) is installed in the case 42.

(2) A temperature sensing part 14 installed in the tank 10 is communicated with the actuator, and a gas of the same type and the same density as the gas 12 in the tank 10 is contained in the temperature sensing part 14 and the actuator which are communicated with each other. 22 is enclosed so that the force f1 of the gas 12 and the force f2 of the gas 22 on the displacement portion 18 of the actuator are applied in opposite directions.

(3) The pointer 32 moves so as to correspond to the displacement of the displacement portion 18.

[Example] As shown in FIG. 1, only the bellows 16 is used.

The case 42 is surrounded by the case 42, the case 42 is directly connected to the tank 10, and the insides thereof are communicated.

The gas 12 enters the case 42 and the displacement portion 18 of the bellows 16 is
Press in the direction of f ₂ .

The displacement portion 18 and the pointer 32 are connected by a rod 44.

[Other Embodiments] In addition to the bellows 16 and the bellows 24, a diaphragm, an air cylinder, or the like can be used.

Therefore, in the claims, these are collectively referred to as an actuator.

[Advantageous effects of the invention] (1) The case 42 is directly connected to and communicates with the tank 10, an actuator is installed in the case 42, and the temperature sensing part 14 installed in the tank 10 is communicated with the actuator. Therefore, the periphery of the actuator is surrounded by the gas 12 in the tank 10. Therefore, the temperature inside the actuator becomes substantially the same as the temperature inside the tank 10.

Therefore, there is almost no pressure difference due to the temperature difference between the temperature sensing unit 14 and the actuator, and no error or malfunction based on it occurs.

(2) Since the actuator is installed in the case 42 directly connected to and communicating with the tank 10, the pressure of the gas 12 in the tank 10 is reduced.
f1 acts on the actuator from the outside to the inside.

Further, since the temperature sensing portion 14 is communicated with the actuator, the pressure f2 of the gas 22 in the temperature sensing portion 14 acts on the actuator in the direction from the inside to the outside.

As a result, the gas 12
Force f1 of the gas 22 and force f2 of the gas 22 are applied in opposite directions.

Therefore, even if only one bellows 16 is used, the tank 10
When the gas 12 leaks from the same, as in the conventional case, f1> f2, and the pointer 32 swings to issue an alarm.

(3) Since only one bellows 16 needs to be used, the tank 10 can be drilled at one place.

Therefore, in the gas-filled tank, the number of holes to cause gas leakage can be reduced as compared with the conventional case.

[Brief description of drawings]

 FIG. 1 is an explanatory diagram of an embodiment of the present invention, and FIG. 2 is an explanatory diagram of a conventional technique. 10: Tank, 12: Gas 14: Temperature sensing part, 16: Bellows 18: Displacement part, 20: Pipe 22: Gas, 24: Bellows 26: Displacement part, 28: Pipe 30: Rod, 32: Pointer 42: Case, 44: Rod

Claims (2)

[Scope of utility model registration request] 1. A tank 10 is directly connected to and communicates with a case 42, and an actuator made of a hermetic container having a displacement portion 18 is installed in the case 42, and the actuator is provided with the hermetic container installed in the tank 10. A temperature sensitive portion 14 consisting of the above, and a gas 22 of the same type and the same density as the gas 12 in the tank 10 is enclosed in the actuator and the communicating temperature sensitive portion 14 to displace the actuator. The force f1 of the gas 12 with respect to 18 and the force f2 of the gas 22 are applied in directions opposite to each other, and the pointer 32 is moved according to the displacement of the displacement portion 18, the difference. Pressure indicator. 2. The differential pressure indicating device according to claim 1, wherein the actuator is a bellows 16.