JPH0112182Y2 - - Google Patents

Description

[Detailed description of the invention] [Purpose of the invention] (Industrial application field) The present invention has elements sensitive to pressure and temperature, and is a gas density system that operates by the stress generated by these two elements. Regarding relays.

(Conventional technology) Recently, SF6 has been used as a switchgear for power transmission and substation systems.
Gas shields, disconnectors, disconnectors, etc. using gas are used. However, in this type of switchgear, when SF6 gas leaks to the outside of the switchgear tank, the gas density decreases, thereby causing a decrease in insulation performance. For this reason, it is necessary to monitor the density of SF6 gas and issue an alarm to the outside when the density drops.

As mentioned above, a gas density relay is a means for monitoring the gas density and issuing an alarm to the outside when the density decreases.

This type of gas density relay has conventionally been disclosed in Japanese Patent Publication No. 11-4271,
There is one shown in Publication No. 78231.

The device disclosed in Japanese Patent Publication No. 11-4271 is a gas density relay used in aircraft altimeters, which activates a container filled with standard gas when the pressure in the sky decreases. The density of the gas is detected by detecting the movement of the gas.

Furthermore, the method disclosed in Japanese Patent Application Laid-Open No. 55-78231 also detects pressure changes between a standard gas and a gas to be measured.

(Problem to be solved by the invention) Since all of the above-mentioned conventional techniques require a standard gas, if this standard gas leaks, the measured value of the density of the gas to be measured is becomes inaccurate.

Therefore, an object of the present invention is to provide a gas density relay that can detect changes in gas density with high precision and reliability without requiring a standard gas.

[Structure of the invention] (Means for solving the problem) The present invention has a structure that takes the following measures in order to solve the above problems and achieve the purpose. That is, the gas density relay according to the present invention is
A cavity having a communication hole for introducing gas in a density measurement tank filled with a gas whose density change is to be detected and having a through hole bored therein; a bellow installed airtight around the bellow, one end of which is inserted into the through hole and connected to a micro switch provided outside the cavity, and the other end is attached to the bottom of the other end of the bellow. a rod that is airtightly fixed; a spring that is engaged with the bottom of the bellows and applies a spring force to the bellows against the gas pressure acting on the bellows when the temperature of the gas is constant; A bimetal that engages with the other end of the rod and applies an opposite force to the bellows in response to a force acting on the bellows due to a change in gas pressure when the temperature of the gas changes. be.

(Function) According to such a configuration, the rod is not operated due to a pressure change caused by a change in gas temperature.
The rod operates when there is a change in pressure due to a change in the density of the gas. Therefore, changes in gas density can be detected without using a standard gas and without the influence of gas temperature.

(Embodiment) An embodiment of the present invention will be described in detail below with reference to a cutaway sectional view shown in FIG. In the figure, the first seat 1
is attached, for example, by screws, to a density measuring tank 2 filled with a gas whose density is to be measured. A packing 3 is interposed between the density measuring tank 2 and the first seat 1 to provide a gas seal. A second seat 4 and a third seat 5 are sequentially stacked on the opposite surface of the first seat 1 and fixed together with bolts, for example. Further, a cover 6 is attached to the first seat 1 with screws or the like, and the upper part is covered with a cover 7.

Here, a vacant space A is formed in a portion surrounded by the first seat 1 and the second seat 4. Further, the empty space A and the inside of the tank 2 communicate with each other via a communication hole 1a provided in the first seat. A through hole is bored in the center of the second seat 4 and the third seat 5, and a rod 9 is inserted through this hole. One end of the bellows 8 is airtightly attached to the second seat 4 by, for example, welding.
Furthermore, the bottom of the bellows 8 is hermetically fixed to the rod 9. A spring 10 is placed between the bottom of the bellows 8 and the seat 5.
is interposed. On the other hand, within the space A, the intermediate portion of the bimetal 11 is fixed to the other end of the rod 10 with a nut 12. This bimetal 11
The periphery of the seat 1 is fixed to the inner peripheral surface of the seat 1 with screws 13. When the temperature rises, this bimetal 11 is configured to be displaced downward in the drawing, which is the same direction as the direction of expansion and contraction of the bellows 8. On the other hand, one end of the rod 9 passes through the third seat 5 and abuts one end of a link 14 disposed inside the cover 6, and the other end passes through the nut 12 and is inserted into the communication hole 1a. . The link 14 is rotatably held on a shaft 15. Then, a hollow screw 16 is screwed into the other end of this link 14, a push rod 17 is disposed in this hollow part, and a spring 18 is interposed between this push rod 17 and the third seat 5.
The other end of the link 14 is pushed up to the stopper limit. In addition, 19 connects the screw 16 to link 1.
It is a lock nut that is fixed to 4. Then, the micro switch 20 is placed opposite the push rod 17.
A plunger for turning on and off is arranged. Note that the micro switch 20 is fixed and held on the third seat 5.
Further, the signal cable of the micro switch 20 is led out to the outside via a terminal block 21 and a connector 22. 23 to 25 are provided for sealing between the atmosphere and the gas or between the atmosphere and the atmosphere by packing, respectively.

The gas density relay configured as described above is attached to the density measuring tank 2 with screws or the like, and gas is injected into the tank 2 at a certain density. As a result, the gas in tank 2 is transferred to bimetal 11 and bellows 8.
, that is, to the vacant room A. In this case, if the gas density is constant, the pressure will increase when the gas temperature increases, and conversely, the pressure will decrease when the gas temperature decreases. Therefore, when the gas density is constant and the gas temperature rises, the bimetal 11 acts to push the bellows 8 downward, and as the gas pressure increases, the bellows 8 is given a force that overcomes the spring 10 and moves upward. Due to the counterbalancing action, the bellows 8 remains stationary and thus the rod 9 fixed to it is also held in place. Similarly, when the gas density is constant and the gas temperature decreases, the force of the bimetal 11 to push the bellows 8 downward becomes weaker, or conversely, the force that pushes the bellows 8 upward acts on the bimetal 11, while the gas pressure decreases and the bellows 8 is spring 10
The bellows 8 and the rod 9 are held in their predetermined positions in this case as well, as the bellows 8 and the rod 9 are held in place by the force that overcomes the gas pressure and moves downward.

To explain in more detail, if the gas is generally a gas with constant density, the relationship between temperature and pressure is P=AT+B
(Here, P: pressure, T: temperature, A, B: density of gas, constants depending on the type), which is a linear relationship. Also, the slope is ΔP/ΔT=A.

In the configuration of the present invention, the slope ΔP/ΔT =CK/kS...Represented by (a).

Here, C: A constant that depends on the bimetal's external dimensions, material, etc., K: Bimetal's curvature constant (deflection sensitivity to temperature), k: Reciprocal of the bimetal's flexural spring constant, S: Effectiveness of bellows 8 If the pressure receiving area and the slope A of the predetermined gas are solved, the above, C,
By selecting K, k, and S, it is possible to hold the rod 9 without moving up and down when the density is constant. Furthermore, the spring 10 is not involved at all in the above equation (a). However, if the spring 10 is not present, the gas pressure P×S applied to the bellows 8 must be supported by the bimetal 11. This is bimetal 11
Excessive stress acts on the parts, leading to damage and reduced reliability. Therefore, the spring 10 supports the gas pressure P×S without applying it to the bimetal 11, and the bimetal 11 supports only the gas pressure change ΔP×S. From the above, the spring 10 is effective in preventing excessive stress on the bimetal 11.

Thus, the rod 9 is held at an equilibrium position between the position of the bellows 8 due to the gas pressure and the spring force of the bimetal 11, and if the density of the gas decreases in this state, the bellows 8 will be pushed downward by the bimetal 11. The force exceeds the gas pressure and moves the rod 9 downward in the drawing. Therefore, one end of the link 14 that comes into contact with the other end of the rod 9 is moved downward in the drawing by the spring force of the spring 18, and the micro switch 20 is operated by the push rod 17 at the other end. The operating signal of this microswitch 20 is then led out to the outside via a signal cable.

Note that when the gas pressure drops significantly or when adjusting the gas density at multiple locations using multiple microswitches, the amount of movement of the rod 9 will increase, and the resulting excessive movement of the link 14 will be absorbed by the push rod 17. can do. That is, the driving force of the microswitch 20 can be maintained at an appropriate value by the spring force of the spring 18. Also, the operation timing of the micro switch 20 is link 1.
4 and the screw 16 can be adjusted as appropriate depending on the screwing position.

Therefore, it is possible to eliminate pressure changes due to changes in gas temperature and detect external leaks etc. in response to changes in density with high precision. Furthermore, according to the above embodiment, since the bimetal sensitive to gas temperature is disposed in the gas, the response to changes in gas temperature is good, and thereby changes in gas density can be reliably detected.

It should be noted that the present invention is not limited to the above-mentioned embodiments, and the configuration shown in FIG. 2 can be adopted. That is, in FIG. 2, the middle part of the bimetal 101 in the first seat 1 is fixed to one end of the rod 9 with a nut 12, and one end of the bimetal 102 is attached to the bimetal 101.
The structure is such that one end of the bimetal 103 is fixed to the other end of the bimetal 102 via a fixing ring 105, and the other end of the bimetal is fixed in the seat 100 with a screw 13. . When the temperature rises, the bimetal is displaced downward in the drawing as shown in FIG. Although the basic principle is the same as in the case of FIG. 1, there is an advantage that the sensitivity can be improved. In other words, the displacement of the rod 9 with respect to the density change is the first
It increases compared to the figure. This is because by using a plurality of bimetals, the deflection sensitivity of the bimetal increases, and the spring constant of the bimetal as a disc spring decreases. In both FIG. 1 and FIG. 2, the outer periphery of the bellows 8 contains gas for density measurement.

[Effect of idea]

As described above, in the present invention, the gas in the density measuring tank filled with the gas whose density change is to be detected is introduced, and a hollow chamber is formed with a through hole in a part thereof, and A bellow is attached airtightly around the bellows, a rod is inserted through the through hole, one end is connected to the micro switch, and the other end is airtightly fixed to the bottom of the other end of the bellows, and a rod is engaged with the bottom of the bellows to control gas flow. A spring that applies a spring force to the bellows against the gas pressure acting on the bellows when the temperature is constant, and a reverse spring that engages the other end of the rod and responds to the force that acts on the bellows due to changes in gas pressure when the gas temperature changes. By equipping the bellows with a bimetal that applies a directional force to the bellows, the rod will not operate due to changes in pressure due to changes in gas temperature, but will not operate when pressure changes due to changes in gas density. Operate.

Therefore, according to the present invention, it is possible to provide a gas density relay that can detect changes in gas density without using a standard gas and without being affected by gas temperature.

[Brief explanation of the drawing]

FIG. 1 is a cutaway front view showing an embodiment of the present invention;
FIG. 2 is a sectional view of a main part showing another embodiment of the present invention using a plurality of bimetals. 8... Bellow, 9... Rod, 10... Spring,
11...Bimetal, 20...Micro switch.

Claims (1)

[Scope of utility model registration request] A cavity having a communication hole for introducing gas in a density measurement tank filled with a gas whose density change is to be detected and having a through hole bored therein; a bellow installed airtight around the bellow, one end of which is inserted into the through hole and connected to a micro switch provided outside the cavity, and the other end is attached to the bottom of the other end of the bellow. a rod that is airtightly fixed; a spring that is engaged with the bottom of the bellows and applies a spring force to the bellows against the gas pressure acting on the bellows when the temperature of the gas is constant; a bimetal that engages the other end of the rod and applies an opposite force to the bellows corresponding to the force acting on the bellows due to a change in gas pressure when the temperature of the gas changes. relay.