JPH0945191A - Differential pressure switch - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prolong the life of an operating power source, reduce its replacing frequency or charging frequency, and facilitate its maintenance by making it usable for a facility exposed to a corrosive fluid and requiring the detection of fine differential pressure such as a vacuum type sewage collecting system, expanding the operating range, and reducing the power consumption. SOLUTION: A pair of diaphragms 2A, 2B fitted to both ends of a connecting rod 6 are arranged in a switch box 1, and the interior is independently divided into three chambers of an intermediate sealed chamber 3 and the first pressure chamber 4 and the second pressure chamber 5 adjoining on both sides. A common moving contact piece 7 provided on the connecting rod 6 is brought into electric contact with the first fixed contact point 8 or the second fixed contact point 9 in the intermediate sealed chamber 3 to form the electrically conducting state in response to the pressure difference between the pressure P1 loaded from the first pressure port 4A to the first pressure chamber 4 and the pressure P2 loaded from the second pressure port 5A to the second pressure chamber 5.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a differential pressure switch, and more particularly, it can be used in equipment such as a vacuum type sewage collection system which is exposed to a corrosive fluid and requires detection of a slight differential pressure. Regarding differential pressure switch.

[0002]

2. Description of the Related Art As a conventional differential pressure switch, for example, one shown in FIG. 2 is known. This differential pressure switch includes a switch box 10 and a diaphragm 13 that divides the inside of the switch box 10 into two chambers, a first pressure chamber 11 and a second pressure chamber 12, and is connected to the first pressure chamber 11. A micro switch 15 is housed in the switch housing chamber 14. The micro switch 15 and the diaphragm 13 are connected to each other by a connecting rod 16 and a first pressure port 11A is provided in the first pressure chamber 11 and a second pressure chamber 12 is provided in the second pressure chamber 12. The structure has two pressure ports 12A.

According to this type of differential pressure switch, the pressure P1 applied from the first pressure port 11A to the first pressure chamber 11 is increased.
And the pressure P2 applied to the second pressure chamber 12 from the second pressure port 12A causes the diaphragm 13 to be displaced, and the micro switch 15 is turned on / off at a set point.

However, when the differential pressure switch is used in, for example, the vacuum valve mass of the vacuum type sewage collection system, corrosive fluid such as dirty water or air in the vacuum valve mass causes the first pressure chamber 11 and the second pressure chamber. Introduced in 12. Even if the corrosive fluid is introduced into the second pressure chamber 12, the micro switch 15
Will not be adversely affected.

However, when the corrosive fluid is introduced into the first pressure chamber 11, the micro switch 15 accommodated in the switch accommodating chamber 14 is exposed to the corrosive fluid, causing corrosion in the electrical terminals. This will shorten the life of the differential pressure switch. Therefore, its use in equipment exposed to corrosive fluids, such as vacuum sewage collection systems, is limited. Further, since it is not suitable for detecting the slight differential pressure, its use in the above-mentioned equipment which requires the detection of the slight differential pressure is also limited.

Further, the ON / O of the microswitch 15 is turned on.
Since current is always conducted in the FF state, power consumption is large and when a battery is used as an operating power source, the operating power source has a short life, and its replacement frequency or charging frequency becomes high, which makes maintenance difficult. It has drawbacks such as

[0007]

That is, in the conventional differential pressure switch, when it is used in equipment exposed to corrosive fluid, corrosion occurs in the electrical terminals and shortens the life of the differential pressure switch. The use range of the switch is limited.
Further, since it is not suitable for detecting a slight differential pressure, its use is limited to equipment requiring detection of a slight differential pressure. Moreover, since the current is always conducted in the ON / OFF state of the micro switch, the power consumption is large and when the battery is used as the operation power supply, the life of the operation power supply is shortened,
It has a drawback that the replacement frequency or the charging frequency becomes high and maintenance becomes difficult. Therefore, the invention according to claim 1 uses the corrosive fluid for electrical terminals even when used in equipment that is exposed to a corrosive fluid such as a vacuum sewage collection system and is required to detect a slight differential pressure. The corrosion resistance of the power supply is extended to prolong its life, and the differential pressure can be detected to expand the range of use and reduce the power consumption, thereby extending the life of the operating power supply and reducing its replacement frequency or charging frequency. The purpose of the present invention is to provide a differential pressure switch that facilitates maintenance.

[0008]

In order to achieve the above object, the invention of claim 1 is a switch box and a connecting rod, which are attached to the connecting rod so as to face each other and are arranged inside the switch box. A pair of diaphragms that independently divides the interior of the chamber into three chambers, a first pressure chamber and a second pressure chamber, which are adjacent to both sides of the intermediate sealed chamber, and the connecting rod in the intermediate sealed chamber. A common movable contact piece provided, and a first fixed contact and a second fixed contact provided between the common movable contact piece and the pair of diaphragms, and a first pressure port provided in the first pressure chamber. In addition, a second pressure port is provided in the second pressure chamber. According to the first aspect of the invention, the pair of diaphragms are connected by the pressure difference between the pressure applied to the first pressure chamber from the first pressure port and the pressure applied to the second pressure chamber from the second pressure port. The rod and the common movable contact are displaced, and the common movable contact is the first at the unique set point.
One of the fixed contact and the second fixed contact is contacted to form an electrical conduction state. Since the common movable contact piece, the first fixed contact, and the second fixed contact are housed in the intermediate sealed chamber, even if the first pressure chamber and the second pressure chamber are used under the condition that they are exposed to a corrosive fluid, they are corroded. It is possible to prevent the common movable contact piece, the first fixed contact, and the second fixed contact from being corroded by the oxidative fluid. Further, even if the air in the intermediate closed chamber slightly expands or contracts due to the change in the external temperature of the switch box, the slight expansion or contraction can be absorbed by the pair of diaphragms. Therefore, the connecting rod and the common movable contact piece are not displaced by the slight expansion and contraction of the air in the intermediate sealed room, and do not come into contact with the first fixed contact or the second fixed contact. That is, the slight differential pressure can be detected while avoiding the occurrence of malfunction due to a slight pressure fluctuation in the intermediate sealed chamber. Further, in the region where the pressure difference is smaller than the specific set point, the common movable contact piece is displaced to cause the first fixed contact or the second fixed contact.
The state where the fixed contact is not contacted, that is, the electrically non-conducting state can be maintained.

[0009]

BEST MODE FOR CARRYING OUT THE INVENTION Embodiments of the invention described in claim 1 will be described below with reference to the drawings. In FIG. 1, reference numeral 1 denotes a switch box, and the inside of the switch box 1 includes an intermediate closed chamber 3 and a first pressure chamber 4 adjacent to both sides of the intermediate closed chamber 3 by a pair of diaphragms 2A and 2B.
And the second pressure chamber 5 are independently divided into three chambers, the first pressure chamber 4 is provided with the first pressure port 4A, and the second pressure chamber 5 is provided with the second pressure port 5A. .

The diaphragms 2A and 2B have their outer peripheral edge portions airtightly or liquidtightly attached to the peripheral wall of the switch box 1, and the central portions thereof are fixed to both axial ends of the connecting rod 6 so that a predetermined distance is maintained. Are disposed inside the switch box 1 so as to face each other.

A common movable contact piece 7 is provided at the axial center of the connecting rod 6.
Are provided so as to project radially outward. Further, a first fixed contact 8 is provided between the common movable contact piece 7 and the diaphragm 2A, and the second fixed contact 9 is provided between the common movable contact piece 7 and the diaphragm 2B. ing.

In the above structure, the pressure difference between the pressure P1 applied from the first pressure port 4A to the first pressure chamber 4 and the pressure P2 applied from the second pressure port 5A to the second pressure chamber 5 makes a pair. The diaphragms 2A, 2B, the connecting rod 6 and the common movable contact piece 7 are displaced, and the common movable contact piece 7 comes into contact with either one of the first fixed contact 8 and the second fixed contact 9 at a specific set point, and the electrical connection is achieved. Form a conductive state. That is,
Due to the relationship of P1> P2, when the pressure difference between P1 and P2 becomes the set point specific to the differential pressure switch, the pair of diaphragms 2A,
2B, the connecting rod 6 and the common movable contact piece 7 are displaced in the arrow Y1 direction, and the common movable contact piece 7 contacts the second fixed contact 9 to form an electrical conduction state. Further, in the relationship of P1 <P2, when the pressure difference between P1 and P2 becomes the set point peculiar to the differential pressure switch, the pair of diaphragms 2A and 2B, the connecting rod 6 and the common movable contact piece 7 move in the direction of the arrow Y2. Upon displacement, the common movable contact piece 7 comes into contact with the first fixed contact 8 to form an electrically conductive state.

Since the common movable contact piece 7, the first fixed contact 8 and the second fixed contact 9 are housed in the intermediate closed chamber 3, the first pressure chamber 4 and the second pressure chamber 5 are sewage and the vacuum valve mass. Even when used in equipment such as a vacuum-type sewage collection system that is exposed to corrosive fluids such as air, the common movable contact piece 7, the first fixed contact 8 and the second fixed contact 9 are corroded by the corrosive fluid. Since this can be prevented and the life of the differential pressure switch can be extended, the range of use of the differential pressure switch can be expanded.

Further, even if the air in the intermediate closed chamber 3 slightly expands or contracts due to the fluctuation of the external temperature of the switch box 1, the slight expansion or contraction of the air causes the pair of diaphragms 2 to move.
Can be absorbed by A and 2B. Therefore, the connecting rod 6 and the common movable contact piece 7 are not displaced by the slight expansion and contraction of the air in the intermediate sealed chamber 3, and do not come into contact with the first fixed contact 8 or the second fixed contact 9. In other words, since it is possible to avoid the occurrence of malfunction due to a slight pressure fluctuation in the intermediate closed chamber 3 due to the fluctuation of the external temperature, it is possible to detect the slight differential pressure.
That is, by reducing the set point peculiar to the differential pressure switch, the common movable contact piece 7 comes into contact with either one of the first fixed contact 8 and the second fixed contact 9 due to the slight differential pressure between P1 and P2, and electrical Even if it is configured to form a static conduction state,
It is possible to reliably avoid the occurrence of malfunction due to slight pressure fluctuations in the intermediate closed chamber 3. From this point, it can be used in equipment such as a vacuum type sewage collection system that requires detection of a slight differential pressure, and the range of use of the differential pressure switch can be expanded.

Further, in the region where the pressure difference is smaller than the specific set point, the common movable contact piece 7 is displaced and does not contact the first fixed contact 8 or the second fixed contact 9, that is, the electrical non-contact as shown in the figure. The conduction state can be maintained. Therefore, when the battery is used as the operating power source because the power consumption is reduced, it is possible to extend the life of the operating power source and reduce the replacement frequency or the charging frequency to facilitate the maintenance.

[0016]

As described above, according to the first aspect of the invention, since the common movable contact piece, the first fixed contact and the second fixed contact are housed in the intermediate sealed chamber, the first pressure chamber and the first pressure chamber 2 Even when used in equipment such as vacuum type sewage collection system where the pressure chamber is exposed to corrosive fluid such as dirty water or air in the vacuum valve mass, the common movable contact piece, first fixed contact and Since the corrosion of the second fixed contact can be prevented and the life of the differential pressure switch can be extended, the range of use of the differential pressure switch can be expanded. Further, even if the air in the intermediate closed chamber slightly expands or contracts due to the fluctuation of the external temperature, the slight expansion or contraction can be absorbed by the pair of diaphragms, so that the set point specific to the differential pressure switch is made small. As a result, the common movable contact piece is brought into contact with either one of the first fixed contact and the second fixed contact due to the slight differential pressure to form an electrically conductive state, so that the occurrence of malfunction can be reliably avoided. , Can be used for equipment that requires detection of a slight differential pressure, such as a vacuum type sewage collection system, and the range of use of the differential pressure switch can be expanded. Furthermore, in the region where the pressure difference is smaller than the specific set point, the electrical non-conduction state is maintained,
Since the power consumption can be reduced, when a battery is used as the operating power source, the operating power source can be extended in life, and the frequency of replacement or charging can be reduced to facilitate maintenance.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention.

FIG. 2 is a sectional view of a conventional example.

[Explanation of symbols]

 1 Switch Box 2A Diaphragm 2B Diaphragm 3 Intermediate Sealing Chamber 4 1st Pressure Chamber 4A 1st Pressure Port 5 2nd Pressure Chamber 5A 2nd Pressure Port 6 Connecting Rod 7 Common Moving Contact 8 1st Fixed Contact 9 2nd Fixed Contact

Claims (1)

[Claims] 1. A switch box and a connecting rod which are attached to each other so as to face each other and are arranged inside the switch box, and the inside of the switch box is an intermediate closed chamber and first pressures adjacent to both sides of the intermediate closed chamber. A pair of diaphragms that are independently divided into three chambers, a chamber and a second pressure chamber, a common movable contact piece provided on the connecting rod in the intermediate sealed chamber, the common movable contact piece and the pair of diaphragms. A first fixed contact and a second fixed contact provided between the diaphragms, wherein the first pressure chamber is provided with a first pressure port, and the second pressure chamber is provided with a second pressure port. Characteristic differential pressure switch.