JPH0330983Y2 - - Google Patents

Description

[Detailed Description of the Invention] [Purpose of the Invention] (Field of Industrial Application) This invention relates to a pressure switch that is attached to, for example, a gas meter and detects fluctuations in gas pressure.

(Prior technology) A pressure sensor that detects gas pressure is installed in a gas meter that instructs the integration of gas consumption by measuring the gas flow rate, and the gas pressure is abnormally reduced due to a defect in the downstream piping of the gas meter, etc. Gas meters equipped with a safety device that activates a shutoff valve device provided in the middle of the gas flow path when such a situation occurs has been put into practical use.

The pressure sensor installed in this type of gas meter has a case body equipped with a bellows or diaphragm that expands and contracts according to the pressure, and the expansion and contraction of the bellows and diaphragm is controlled by a plunger that is pivotally supported by the case body to move an action switch. The action switch is configured to operate in conjunction with the contact member when the pressure received by the pressure receiving portion of the bellows or diaphragm, that is, the gas pressure exceeds a set value.

Incidentally, the bellows or diaphragm generally has its periphery fixed to the upper surface of a base constituting the switch body, and a pressure introduction hole is provided in the pressure receiving surface of the base to communicate with the pressure receiving chamber. The base has a flat plate shape, and a plurality of mounting holes are provided in the flange portion of the peripheral edge of the base.

Therefore, when installing a pressure switch in the valve chamber of a gas meter, insert the pressure switch into the installation hole provided in the partition wall, and secure the flange of its base to the partition wall by tightening multiple installation screws. are doing. The pressure receiving surface of the base is arranged to face the valve chamber, and the gas pressure in the valve chamber is sensed.

(Problem to be solved by the invention) However, the conventional base is flat, with the central part serving as the pressure-receiving surface and the peripheral flange part serving as the mounting part for the mounted member. Since the base is tightened and fixed to the member to be attached, the pressure receiving surface of the base may be deformed depending on the magnitude of the tightening torque. When the pressure receiving surface portion deforms in this manner, the diaphragm fixed to the upper surface of the base is deformed, causing a disadvantage that the initial set pressure of the diaphragm changes.

This idea was made with attention to the above-mentioned situation, and its purpose is to prevent the diaphragm from tightening even if some tightening torque is applied to the base when installing the pressure switch to the member to which it is attached. To provide a pressure switch that does not change the set pressure and can improve installation workability without using extra nerves during installation.

[Structure of the idea]

(Means and effects for solving the problem) This invention forms a concave part in the lower pressure receiving surface of the base with a diaphragm fixed to the upper surface, and forms a step between it and the flange part formed on the periphery of the base. However, the structure is such that the tightening torque when attaching the flange portion to the member to be attached is not applied to the pressure receiving surface portion.

(Example) Hereinafter, an example of this invention will be described based on the drawings.

1 and 2 show a pressure switch, and FIG. 3 shows a gas meter incorporating a pressure switch. First, the pressure switch will be described. Reference numeral 1 denotes a base, and the base 1 is integrally provided with a pressure receiving surface portion 2 having a concave lower portion and a flange portion 3 on the periphery thereof. Therefore, a step is formed between the pressure receiving surface portion 2 and the flange portion 3. A pressure introduction hole 4 is provided in the center of the pressure receiving surface portion 2, and a plurality of attachment holes 5 are provided in the flange portion 3. A diaphragm 7 forming a pressure receiving chamber 6 communicating with the pressure introduction hole 4 is provided at the upper part of the base 1 .
The diaphragm 7 is formed of a thin metal plate material having corrosion resistance into a substantially conical shape, and has a wavy uneven portion 8 on its outer peripheral surface. A convex portion 9 is formed in the center of the diaphragm 7, and the peripheral portion is hermetically fixed to the base 1 by laser welding. Furthermore, a switch box 10 is provided on the top of the base 1 so as to enclose the diaphragm 7. This switch box 10 is comprised of a box body 11 molded from an insulating material and a case body 12 deformed from a metal material. A plurality of locking pawls 13 are provided on the outer periphery of the box body 11, and an engaging hole 14 that also serves as a ventilation hole is provided in the side wall of the case body 12 corresponding to these locking pawls 13. The claw 13 is inserted into the locking hole 14
It is integrally constructed by being elastically locked to. The lower end of the case body 12 is fitted into the pressure receiving surface 2 of the base 1, and the fitting is joined by spot welding.
Further, the opening at the lower end of the box body 11 is closed by a stopper plate 15, and a sliding hole 16 is bored in the center of the stopper plate 15 in the vertical direction. A plunger 17 whose lower end surface contacts the convex portion 9 of the diaphragm 7 is slidably inserted into the sliding hole 16 in the axial direction, and the point contact portion 18 at the upper end projects into the switch chamber 19 of the box body 11. ing. Further, an action switch 20 is provided inside the switch chamber 19.
To explain this action switch 20, there is a movable contact member 21 made of a leaf spring, which is operated by a movable contact piece 22, an elastic drive piece 23 integrated with this movable contact piece 22, and a U-shaped reversing spring 24. It is formed. The free end portion of the elastic drive piece 23 is in contact with the point contact portion 18 of the plunger 17, and the stroke of the plunger 17, which advances and retreats due to the expansion and contraction of the diaphragm 7, is at a certain level (the dead end of the reversing spring 24). When the contact point 22 is exceeded, the movable contact piece 22 is reversed by the rapid reversing action of the reversing spring 24. A movable contact 25 is provided at the free end of the movable contact piece 22, and a first fixed terminal 26 is provided on the box body 11 facing the movable contact 25. Furthermore, a movable terminal 27 is provided on the lower surface of the movable contact member 21 located on the fulcrum side. This movable terminal 27 has a substantially U-shape, and both ends thereof are movable up and down relative to guide grooves 28, 28 provided in the upper part of the box body 11, and are supported non-rotatably. A screw hole 29 is vertically bored in the bottom of the movable terminal 27, and the box body 11 is inserted into the screw hole 29.
Adjustment screw 30 inserted downward from the top wall
are screwed together. Further, a boss 31 is provided protrudingly on the box body 11 facing the movable terminal 27, and the boss 31 has a substantially U-shape with one end penetrating the upper wall of the box body 11 and protruding to the outside. A second fixed terminal 32 is provided. A conductive spring 33 made of a coil spring is interposed between the second fixed terminal 32 and the fulcrum side of the movable contact member 21 in a compressed state.
In other words, the movable contact member 21 and the second fixed terminal 32
is in an electrically conductive state by a conductive spring 33.

A pressure switch constructed in this way is attached to a gas meter, for example, as shown in FIG. That is, the case body 34 of the gas meter is provided with a partition wall 37 as a mounting member that partitions the valve chamber 35 and the electrical equipment room 36, and the partition wall 37 is provided with a mounting hole 38. Then, insert the switchbox 10 of the pressure switch into the mounting hole 38, and with the flange 3 of the base 1 joined to the lower surface of the partition wall 37, insert the mounting screw 39 into the mounting hole 5, and then insert the mounting screw 39 into the mounting hole 38.
It is fixed by screwing it into place. At this time, a tightening torque is applied to the base 1 when tightening the mounting screws 39, but since a step is formed between the pressure receiving surface portion 2 and the flange portion 3 of the base 1, the tightening torque is applied to the pressure receiving surface portion 2. The diaphragm 7 fixed to the upper surface of the pressure receiving surface section 2 is not deformed. Therefore, the initial set pressure of the diaphragm 7 does not change upon installation. By mounting in this manner, the pressure receiving surface portion 2 of the pressure switch faces the valve chamber 35, and the gas pressure in the valve chamber 35 can be sensed.

Next, the operation of the pressure switch constructed as described above will be explained. If the gas pressure in the valve chamber 35 of the gas meter is above a certain level, the gas pressure is received by the diaphragm 7 through the pressure introduction hole 4 provided in the pressure receiving surface portion 2 of the pressure sensor, and the diaphragm 7 is in an expanded state. Therefore, since the elastic drive piece 23 of the action switch 20 is pushed up via the plunger 17, the movable contact piece 22 is urged downward via the reversing spring 24.
The movable contact 25 is separated from the first fixed terminal 26 and is in a switched off state. However, when gas leaks from gas piping, gas appliances, etc. and the gas pressure in the valve chamber 35 of the gas meter decreases, the pressure applied to the diaphragm 7 also decreases. Therefore, the diaphragm 7 is compressed, and the elastic drive piece 23 of the action switch 20 follows and moves down via the plunger 17, so the movable contact piece 23 moves down via the reversing spring 24.
2 is urged upward, and the movable contact 25 comes into contact with the first fixed terminal 26 to be in the switch-on state. When the action switch 20 is turned on, an actuation signal can be outputted to a cutoff device that cuts off the gas flow path via a control circuit (not shown). Therefore, by providing a pressure sensor in the gas meter, the pressure of the gas flowing through the gas meter can be constantly sensed, and when a pressure drop occurs, the shutoff device can be operated to shut off the gas flow.

Further, the set pressure of the pressure sensor, that is, the operating point of the action switch 20 can be arbitrarily varied. That is, since the box body 11 is provided with the adjusting screw 30, by rotating the adjusting screw 30 with a screwdriver or the like, the movable terminal 27 screwed thereon can be raised or lowered. In this case, since the movable terminal 27 is urged downward by the conductive spring 33, when the adjusting screw 30 is rotated, for example, to the right, it is moved upward against the urging force of the conductive spring 33. By rotating it, it can be moved downward by the biasing force. Therefore, the operating point can be finely adjusted as desired by moving the fulcrum side of the movable contact member 21 up and down.

In the above embodiment, the pressure sensor was installed in the valve chamber of the gas meter, and when the gas pressure decreased below a certain level, the action switch was turned on and used as a safety device to cut off the gas flow. This invention is not limited to the above embodiments,
It can be applied to all types of equipment as a pressure detector that detects the pressure of fluids such as gas.

[Effect of idea]

As explained above, according to this invention, the pressure-receiving surface of the base on which the diaphragm is attached is formed into a recessed part, and a step is formed between it and the flange, so that the pressure switch can be mounted on a member such as a gas meter. When installing the pressure switch, even if a tightening torque is applied, the diaphragm will not be deformed and the initial set pressure will not change, so there is no need to use extra nerves when installing the pressure switch, and the installation work efficiency can be improved. play.

[Brief explanation of the drawing]

The drawing shows one embodiment of this invention.
2 is a longitudinal sectional front view of the pressure switch, FIG. 2 is a longitudinal sectional side view, and FIG. 3 is a partially cutaway side view of the gas meter to which the pressure switch is attached. DESCRIPTION OF SYMBOLS 1... Base, 2... Pressure receiving surface part, 3... Flange part, 4... Pressure introduction hole, 6... Pressure receiving chamber, 7...
Diaphragm, 10...Switch box, 17
...Plunger, 20...Action switch,
36...Partition wall (attached member).

Claims (1)

[Scope of utility model registration request] A base having a pressure receiving surface portion having a pressure introduction hole, a flange portion on the periphery thereof for attachment to a member to be attached, and a diaphragm having the periphery fixed to the base and forming a pressure receiving chamber communicating with the pressure introduction hole. and a switch box provided on the base, and an action that is turned on and off by the diaphragm, which has a movable contact member provided inside the switch box and comes into contact with the diaphragm via a plunger, and expands and contracts under pressure. 1. A pressure switch comprising a pressure switch, characterized in that the lower part of the base is formed as a recessed part relative to the flange part, and the periphery of the diaphragm is fixed to the upper part corresponding to the recessed part.