JPS623887B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a gas flow meter that measures gas flow rate by reciprocating movement of a metering membrane based on gas pressure.

Conventional membrane gas flowmeters consist of two housings with measuring chambers on both sides of the measuring membrane, that is, two measuring membranes and four measuring chambers, and the reciprocating motion of each membrane is controlled by a crank. This was converted into a rotational movement of two switching valve operating rods via a mechanism, which operated the switching valves to switch the flow of gas to each metering chamber.
In order to obtain smooth rotational movement with the crank mechanism,
The two operating rods must be placed approximately 90 degrees apart from each other in terms of crank angle, so they are separated from each other by approximately 90 degrees from each other.
Gas is discharged 90 degrees out of phase. Moreover, since the switching valve is operated gradually, gas is discharged from both housings in a sine curve, for example. Therefore, the gas discharged from both housings pulsates as a whole, and the flow rate fluctuates. Furthermore, the amount of gas discharged is small compared to the volume of each metering chamber, resulting in a large gas flowmeter. In addition, in conventional gas flow meters, the gas inlet and outlet are arranged in the same direction, which not only results in a complicated flow path within the gas flow meter and relatively large pressure loss, but also requires a complicated piping route. It was necessary to install piping.

An object of the present invention is to solve the above-mentioned technical problems and provide a compact gas flow meter that has low pressure loss and prevents pulsation.

Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 is a sectional view of an embodiment of the present invention.
Two measuring chambers 3 and 4 are formed within the housing 1 and partitioned by a measuring membrane 2 . In the measuring chamber 3, the first
As shown in the figure, an inlet valve hole 5a and an outlet valve hole 5b having axes on a straight line parallel to the metering membrane 2 in a neutral state are formed. Similarly, the metering chamber 4 is formed with an inlet valve hole 6a and an outlet valve hole 6b whose axes lie on a straight line parallel to the metering membrane 2. An inlet gas chamber 7 is commonly provided outside the inlet valve holes 5a, 6a of the housing 1, and an outlet gas chamber 8 is commonly provided outside the outlet valve holes 5b, 6b. As will be described later, the gas flowing into the inlet gas chamber 7 is caused to alternately flow into the two metering chambers 3 and 4 by the switching valve 10 which is switched instantaneously, and from both the metering chambers 3 and 4 to the outlet. It is alternately discharged into the gas chamber 8. By that,
A metering membrane 2 and a first actuating rod 1 integral with the metering membrane 2
1 is reciprocated to the left and right in FIG. A permanent magnet 13 is fixed to one end of the second operating rod 12, and the gas flow rate is measured by a counter 14 that is linked to the reciprocating movement of the permanent magnet 13.

The switching valve 10 includes a pair of drive rods 15 and 16, a flat valve body 17 fixed to both ends of each of the drive rods 15 and 16, and a pair of connections connecting both ends of the drive rods 15 and 16. Includes rods 18 and 19. The drive rod 15 is connected to the inlet and outlet valve holes 5 of the metering chamber 3.
a and 5b movably through the same axis. Similarly, the drive rod 16 movably passes through the inlet and outlet valve holes 6a, 6b of the metering chamber 4 along the same axis. The valve body 17 is fixed to both ends of each drive rod 15, 16 at right angles to the axis of each drive rod 15, 16. Both ends of the connecting rods 18 and 19 are connected to the drive rod 15,
It is pin-coupled to both ends of 16. The connecting rod 18 is
A leaf spring portion 18a extending from one end of the drive rod 15 to a position closer to the drive rod 16 than the center position of both drive rods 15, 16, and a rigid portion 18b from the leaf spring portion 18a to one end of the drive rod 16. Become.
Similarly, the connecting rod 19 includes a leaf spring portion 19a extending from the other end of the drive rod 15 to a position closer to the drive rod 16 than the center position of both the drive rods 15 and 16, and a leaf spring portion 19a extending from the leaf spring portion 19a to the drive rod 16. The rigid portion 19b extends to the other end. Both connecting rods 18, 19
The leaf spring portions 18a, 19a and the rigid portion 18
b and 19b, the drive rods 15 and 16 are pivotally supported in the housing 1 by pins 20 and 21 perpendicular to their axes.

Figure 2 shows the first operating rod 11 and the second operating rod 12.
It is a perspective view of the vicinity. A membrane plate 2a is attached to the center of the metering membrane 2. In the measuring chamber 4, in the center of the membrane plate 2a, there is a first plate extending perpendicularly to the membrane plate 2a.
One end of the operating rod 11 is fixed. 1st operating rod 1
1, a second operating rod 12 is provided so as to intersect the first operating rod 11 at right angles. The first operating rod 11 and the second operating rod 12 are movable in the longitudinal direction and are guided by a guide 22 shown in phantom lines in FIG. In FIG. 1, this guide 22 is omitted for the sake of simplicity. A first sliding contact piece 23 is fixed to the middle of the first operating rod 11, and a second sliding contact piece 24 is fixed to the other end of the second operating rod 12. First sliding contact piece 2
3 is formed with sliding surfaces 23a and 23b at both ends of the second operating rod 12 in the moving direction, and the second sliding piece 24 is formed with corresponding sliding surfaces 24a and 24b.

A torsion spring 25 as a snap action actuating means is attached to the first actuating rod 11 and the second actuating rod 12.
It is provided so as to gently surround an axis 27 that is perpendicular to the direction of movement. One end of the torsion spring 25 is pin-coupled to the other end of the first actuating rod 11, and the other end is pin-coupled to the middle of the second actuating rod 12. The drive rod actuating means 26 for actuating the drive rod 16 includes a leaf spring portion 26a whose one end is fixed at right angles to the middle of the second actuation rod 12, and a leaf spring portion 26a whose one end is fixed to the other end of the leaf spring portion 26a. The rigid portion 26c is connected via a pin 26b perpendicular to the paper plane of FIG. In this way, the plate spring portion 26a is connected to the pin 26b and the rigid portion 26.
By connecting to the drive rod 16 via c,
The drive rod 16 and the second operating rod 12 can be moved relative to each other in the longitudinal direction.

Assume that gas flows into the inlet gas chamber 7 when the metering membrane 2 and the switching valve 10 are in the state shown in FIG. At this time, the inlet valve hole 5a of the metering chamber 3 is closed with the valve body 17, and the inlet valve hole 6a of the metering chamber 4 is open, so gas flows into the metering chamber 4 from the inlet gas chamber 7. be done. Since the outlet valve hole 6b of the metering chamber 4 is closed by the valve body 17, the pressure of the gas flowing into the metering chamber 4 presses and displaces the metering membrane 2 toward the metering chamber 3 side. Due to this displacement of the metering membrane 2, the gas in the metering chamber 3 flows out into the outlet gas chamber 8 through the opened outlet valve hole 5b.

According to the displacement of the metering membrane 2 toward the metering chamber 3, the first
The operating rod 11 is also moved together in the direction of arrow 28. This movement of the first operating rod 11 in the direction of the arrow 28 causes the torsion spring 25 to move the second operating rod 1
A force is accumulated that urges 2 in the direction of arrow 29.
At this time, the sliding contact surface 23a of the first sliding contact piece 23 and the sliding contact surface 24a of the second sliding contact piece 24 are in sliding contact with each other, and the first sliding contact piece 23 is larger than the second sliding contact piece 24. Arrow 2 of the second operating rod 12 until it is displaced toward the metering membrane 2 side.
Movement in the direction of 9 is suppressed. and the first
When the second sliding contact pieces 23 and 24 come out of sliding contact, the second operating rod 12 is momentarily moved in the direction of arrow 29 by the spring force of the torsion spring 25, as shown in FIG. Ru.

The movement of the second actuating rod 12 in the direction of arrow 29 generates a force in the leaf spring portion 26a of the drive rod actuating means 26 that urges the drive rod 16 in the direction of arrow 30. As a result, the drive rod 16 is momentarily moved in the direction of the arrow 30, and the drive rod 15 is accordingly moved via the connecting rods 18, 19 in the direction of the arrow 31. Therefore, the inlet valve hole 6a of the metering chamber 4 is closed and the outlet valve hole 6b is opened, and the inlet valve hole 5a of the metering chamber 3 is opened and the outlet valve hole 5b is closed. Since the connecting rods 18 and 19 are pivotally supported by pins 20 and 21 closer to the driving rod 16 than the center position of both driving rods 15 and 16, the leaf spring portions 18a and 19a of the connecting rods 18 and 19 are A force is generated that urges the drive rod 15 in the direction of arrow 31. Therefore, the valve body 17 is brought into close contact with the valve seat at the outlet valve hole 5b of the metering chamber 3, and is reliably sealed.

Depending on the switching operation of the switching valve 10, the inlet gas chamber 7
The gas flows into the metering chamber 3 from the inlet valve hole 5a. Since the outlet valve hole 5b of the metering chamber 3 is closed, the pressure of the gas flowing into the metering chamber 3 presses and displaces the metering membrane 2 toward the metering chamber 4 side. By the displacement of the metering membrane 2 toward the metering chamber 4, the gas in the metering chamber 4 flows out into the outlet gas chamber 8 through the opened outlet valve hole 6b.

In response to the displacement of the metering membrane 2 toward the metering chamber 4, the first operating rod 11 is also integrally moved in the direction opposite to the arrow 28. This movement of the first actuating rod 11 in the direction opposite to the arrow 28 causes the torsion spring 25 to move the second actuating rod 1
A spring force is accumulated that urges 2 from the state shown in FIG. 3 in the direction opposite to arrow 29. At this time, the first sliding contact piece 23
The sliding contact surface 23b of the second sliding contact piece 24 and the sliding contact surface 24b of the second sliding contact piece 24
are in sliding contact with each other, and until the first sliding contact piece 23 is displaced to a position opposite to the metering membrane 2 with respect to the second sliding contact piece 24, the direction opposite to the arrow 29 of the second operating rod 12 Movement to is suppressed. When the first and second sliding contact pieces 23 and 24 come out of sliding contact, the second
As shown in FIG. 4, the operating rod 12 is momentarily moved in the opposite direction of the arrow 29 by the spring force of the torsion spring 25.

By moving the second actuating rod 12 in the direction opposite to the arrow 29, the leaf spring portion 26a of the drive rod actuating means 26
, a force is generated that urges the drive rod 16 in the direction opposite to the arrow 30. The drive rod 16 is thereby moved to the arrow 30
The drive rod 15 is momentarily moved in the opposite direction.
is moved in the opposite direction of the arrow 31 via the connecting rods 18, 19. Therefore, the inlet valve hole 6a of the measuring chamber 4
is opened and the outlet valve hole 6b is closed, and
The inlet valve hole 5a of the metering chamber 3 is closed and the outlet valve hole 5 is closed.
b is opened. At this time, as described above, the valve body 17 is brought into close contact with the valve seat in the inlet valve hole 5a of the metering chamber 3 by the spring force of the plate spring portions 18a, 19a, and a reliable seal is achieved.

In this way, by the switching operation of the switching valve 10, gas in the inlet gas chamber 7 is alternately flowed into the metering chambers 3 and 4, and from the metering chambers 3 and 4 to the outlet gas chamber 8.
The second operating rod 12 is reciprocated in its longitudinal direction accordingly. Thereby, the second
A counter 14 operates in conjunction with a permanent magnet 13 fixed to one end of the operating rod 12 to measure the flow rate of gas.

FIG. 5 is a perspective view of a snap-action actuating means according to another embodiment of the invention, and parts corresponding to those in the embodiment of FIGS. 1 to 4 are given the same reference numerals.
In this embodiment, gears 36 and 37 are individually rotatably fitted onto a shaft 35 perpendicular to the first operating rod 11 and the second operating rod 12. This gear 36, 37
are connected by a helical spring 38 surrounding the shaft 35. Teeth 39 that mesh with the gear 36 are formed on the first operating rod 11 along the moving direction. Furthermore, teeth 40 that mesh with the gear 37 are formed on the second operating rod 12 along the moving direction.

Assume that the first operating rod 11 moves integrally with the metering membrane 2 (see FIG. 1) in the direction of arrow 28. In response to this movement of the first actuating rod 11 in the direction of the arrow 28, the gear 36 meshing with the teeth 39 moves onto the shaft 35.
41 in the direction of arrow 41. As the gear 36 rotates in the direction of arrow 41, a spring force is accumulated in the helical spring 38 that biases the gear 37 in the direction of arrow 41. When the first and second sliding contact pieces 23 and 24 come out of sliding contact, the gear 37 is momentarily rotated in the direction of arrow 41 by the spring force of the helical spring 38, and the second operating rod is accordingly rotated. 12 is an arrow mark 29
is moved instantaneously in the direction of This second operating rod 1
In response to movement in the direction of arrow 29 of 2, the switching valve 10
(See FIG. 1) are switched in the same manner as in the embodiments of FIGS. 1 to 4.

Even when the first operating rod 11 moves in the opposite direction to the arrow 28, the second operating rod 11 is moved in the same manner as described above.
2 is instantaneously moved in the opposite direction of arrow 29.

According to this embodiment, the space occupied by the torsion spring 25 in the embodiments of FIGS. 1 to 4 becomes unnecessary, and the housing 1 can be made smaller.

In each of the embodiments shown in FIGS. 1 to 4 and 5, the spring force of the torsion spring 25 and the helical spring 38 is transmitted to the metering membrane 2 via the first operating rod 11, and the spring force is It changes according to the movement of the first operating rod 11. Therefore, the force with which the gas flowing into the metering chambers 3 and 4 displaces the metering membrane 2 changes according to the displacement of the metering membrane 2, and therefore the pressure loss of the gas in the metering chambers 3 and 4 pulsates. do. A means for preventing this pressure loss pulsation will be described below.

FIG. 6 is a front view of another embodiment of the present invention,
Parts corresponding to the embodiments of FIGS. 1 to 4 are given the same reference numerals. A T-shaped swinging rod 47 consisting of an arm 45 and an arm 46 fixed at right angles to the central portion of the arm 45 is pivotally supported by a pin 48 at the connecting portion of the arms 45 and 46. The pin 48 is perpendicular to the first and second actuating rods 11,12. One end of the arm 45 is
It is connected to a connecting position 49 in the middle of the first operating rod 11 via a compensation spring 50. The other end of the arm 45 is connected to the first operating rod 11 at a connecting position 49 via a compensation spring 51.
connected to. An end of the arm 46 is connected via a pin 54 to the other end of a connecting member 53 whose one end is pin-coupled to the second operating rod 12 . Pin 54 is parallel to pin 48.

FIG. 7 is a front view showing the progress of the movement of the first actuating rod 11 as it moves in the direction of the arrow 28, and FIG. 8 is a graph showing the force F1 exerted by the compensation spring 50 on the first actuating rod 11. FIG. 9 is a graph showing the force F2 that the compensation spring 51 acts on the first operating rod 11. In FIGS. 8 and 9, the force acting in the direction of arrow 28 is positive on the vertical axis. FIG. 71 shows a state corresponding to FIG. 4 of the embodiment of FIGS. 1 to 4, and shows a state in which the first operating rod 11 is displaced to the maximum extent toward the measuring chamber 4 side. The force acting on the first operating rod 11 of the compensation springs 50, 51 at this time is shown at position A in FIGS. 8 and 9. The compensation spring 50 biases the first actuating rod 11 in the direction of the arrow 28, and the compensating spring 51 biases the first actuating rod 11 in the opposite direction of the arrow 28 with a force smaller than the spring force of the compensating spring 50. to strengthen

As the first operating rod 11 moves in the direction of arrow 28, the swinging rod 47 is rotated around the pin 48 in the direction of arrow 55. When the first actuating rod 11 reaches the position shown in FIG. 7(2), the force acting on the first actuating rod 11 of the compensation springs 50, 51 is shown at position B in FIGS. 8 and 9. At this time, the direction in which the spring force of the compensation spring 51 acts is a direction perpendicular to the first operating rod 11, and no force in the direction along the arrow 28 acts on the first operating rod 11.

When the state of FIG. 7(3) is reached, the compensation spring 50,
The force exerted by 51 on the first actuating rod 11 is shown at position c in FIGS. 8 and 9. At this time, both the compensation springs 50 and 51 are attached to the first actuating rod 11 at the arrow mark 2.
Forces act in eight directions.

When the state shown in Fig. 7 (4) is reached, the compensation spring 5
The force 0.51 acting on the first actuating rod 11 is shown at position D in FIGS. 8 and 9. At this time, the direction in which the spring force of the compensation spring 50 acts is a direction perpendicular to the first operating rod 11, and the force of the compensation spring 50 along the arrow 28 is zero.

FIG. 7(5) shows a state in which the first operating rod 11 is displaced to the maximum extent toward the measuring chamber 3 side. Compensation spring 5 at this time
The force acting on the first operating rod 11 of 0.51 is shown at position E in FIGS. 8 and 9. In this state, the sliding contact between the first and second sliding contact pieces 23 and 24 is released, and the spring force of the compensation springs 50 and 51 causes the second operating rod 12 to is instantaneously moved in the direction of arrow 29. In response to the movement of the second actuating rod 12, the driving rod 16 is moved via the aforementioned driving rod actuating means 26, and the switching valve 10 is instantaneously switched.

FIG. 10 shows the first operating rod 1 of the compensation springs 50, 51.
1 is a graph showing a force F that is a composite of forces F1 and F2 acting on a single point. As can be seen from Figure 10, the first
The force acting on the operating rod 11 is approximately constant regardless of the position of the first operating rod 11. Therefore, the metering membrane 2
The force acting on the metering chambers 3 and 4 becomes approximately constant, and the pressure loss of the gas within the metering chambers 3 and 4 remains approximately constant without any pulsation.

FIG. 11 is a sectional view of another embodiment of the present invention, and parts corresponding to the embodiment of FIGS. 1 to 4 are given the same reference numerals. This example is shown in Figures 1 to 4.
Similar to the embodiment shown, it should be noted that a compression spring 75 is provided in addition to the previously described helical spring 25 as the snap action actuating means. One end of the compression spring 75 is connected to a position where the helical spring 25 is connected to the first operating rod 11, and the other end is connected to the housing 1. This compression spring 75 is perpendicular to the first operating rod 11 when the metering membrane 2 is in the neutral state as shown in FIG. 11, and has a spring force in its extension direction.

Assume that the first operating rod 11 moves integrally with the metering membrane 2 from the state shown in FIG. 11 in the direction of arrow 28. When the first operating rod 11 moves in the direction of arrow 28 from the state shown in FIG. . Due to this force, a pressing force in the direction of arrow 28 acts on the first operating rod 11 and the metering membrane 2. At this time, the second operating rod 1
Since the movement of the helical spring 25 in the direction of the arrow 29 is suppressed, the movement of the helical spring 25 in the direction of the arrow 29 is suppressed.
A spring force in the opposite direction to 8 is acting. Therefore,
A compression spring 7 is attached to the first operating rod 11 and the metering membrane 2.
5 in the direction of the arrow 28 and a spring force of the helical spring 25 in the direction opposite to the arrow 28 act. Therefore, a substantially constant force acts on the metering membrane 2 regardless of the displacement of the metering membrane 2, similar to the embodiments shown in FIGS. 6 to 10.

When the first operating rod 11 moves in the direction opposite to the arrow 28, the spring force of the helical spring 25 in the direction of the arrow 28 and the spring force of the compression spring 75 in the opposite direction to the arrow 28 act. . Therefore, in this case as well, a substantially constant force acts on the metering membrane 2 regardless of its displacement.

FIG. 12 is a sectional view of another embodiment of the present invention, and FIG. 13 is a sectional view taken from the cutting plane line - of FIG. 12, and corresponds to the embodiment of FIGS. 1 to 4. Parts are given the same reference numerals. In this embodiment, temperature correction of the gas flow rate is performed by changing the amount of displacement of the metering membrane 2 in accordance with the temperature of the gas.
One end of a bimetal 55 extending substantially parallel to the membrane plate 2a is fixed to the end of the membrane plate 2a of the metering membrane 2. The other end of the bimetal 55 is connected to one end of a displacement rod 57 via a pin 56 near the center of the membrane plate 2 . The displacement rod 57 extends parallel to the first operating rod 11 . The first sliding contact piece 2 fixed to the first operating rod 11
3 is formed with a through hole 58 extending in the direction of movement of the first actuating rod 11. A sliding contact piece 59 is fixed to the other end of the displacement rod 57 and is slidably inserted through the through hole 58 .

The area of the metering membrane 2 is S, the amount of movement of the metering membrane 2 is l,
If the amount of gas passing through the gas flow meter is V, then
The gas count value N is expressed as the number of reciprocating movements of the metering membrane 2, so N=V/S·l (1). Here, S·l is the amount of gas discharged into the outlet gas chamber 8 in one reciprocating movement of the metering membrane 2. If the amount of gas at a gas temperature of 0°C is V ₀ , then the gas temperature t
The gas amount at ℃ is V=V ₀ t+273/273 (2). From equations (1) and (2), N=V ₀ t+273/273·S·l ...(3). Here, the amount of movement l of the metering membrane 2 is made proportional to the absolute temperature (t+273). In other words, the constant of proportionality is α
Assuming that l=α(t+273)...(4), then from equation (3), N=V ₀ 1/273・S・α...(5), and the count value N is independent of the fluctuation of the gas temperature. Shows the amount of gas at a temperature of 0°C.

In this embodiment, the amount of movement of the sliding contact piece 59 is made proportional to (t+273) by the action of the bimetal 55. By doing so, the displacement distance of the metering membrane 2 is controlled by the temperature of the gas. Therefore(5)
As shown in the formula, the count value N can be expressed based on the gas amount at a temperature of 0° C., regardless of fluctuations in gas temperature.

FIG. 14 is a sectional view of another embodiment of the present invention, and parts corresponding to the embodiment of FIGS. 1 to 4 are given the same reference numerals. In this embodiment, the pressure of the gas flow rate is corrected by changing the amount of displacement of the metering membrane 2 in accordance with the gas pressure. Membrane plate on measuring chamber 4 side
A space 62 is airtightly formed in the center of 2a by a cylindrical bellows 60 and an end plate 61. The first operating rod 11 is fixed to the membrane plate 2a by a support arm 63. A through hole 64 extending in the moving direction of the first operating rod 11 is formed in the first sliding contact piece 23 fixed to the first operating rod 11 . The end plate 61 of the space 62 has a first displacement rod 6 extending parallel to the first operating rod 11.
One end of 5 is fixed. Teeth 66 are formed at the other end of the first displacement rod 65 along its longitudinal direction. A swinging rod 68 extending in the radial direction is integrally provided on the shaft of a gear 67 that meshes with the teeth 66 . One end of a second displacement rod 69 extending parallel to the first displacement rod 65 is pin-coupled to an end of a swinging rod 68 . Second
A sliding contact piece 70 is fixed to the other end of the displacement rod 69. This sliding contact piece 70 is connected to the through hole 6 of the first sliding contact piece 23.
4 so as to be freely displaceable.

When the amount of gas at 1 atmosphere is V ₀ ′, the amount of gas V _p when the gas pressure is p is expressed as V _p =V ₀ ′·1/p (6). Further, the count value N is expressed as N=V _p /S·l (7). From equations (6) and (7), N=V ₀ ′/S・l・1/p (8). Here, the displacement l of the measuring membrane 2 is (1/p)
be proportional to. In other words, if the proportionality constant is β, and l = β・1/p ...(9), then from equation (8), N=V ₀ '/S・β ...(10), and the count value N is the gas pressure. 1 regardless of the fluctuation of
The value is based on the amount of gas at atmospheric pressure.

In this embodiment, the space 62 is kept under vacuum.
Then, the amount of expansion and contraction of the bellows 60 and the end plate 61 is proportional to the gas pressure p. The amount of expansion and contraction of the end plate 61 is converted into the amount of movement of the second displacement rod 69 proportional to (1/p) via the first displacement rod 65, gear 67, and swinging rod 68. Thereby, the amount of movement of the sliding contact piece 70 can be made proportional to (1/p), and the amount of movement of the metering membrane 2 can be controlled by the pressure of the gas. Therefore, as shown in equation (10), the count value N can be expressed based on the gas amount at 1 atmosphere, regardless of fluctuations in gas pressure.

In another embodiment of the present invention, gas is sealed in the space 62. Then the bellows 60 and the end plate 61
The amount of expansion and contraction of is proportional to the absolute temperature of the gas and inversely proportional to the pressure of the gas. That is, l∝(273+t)/p (11), and the temperature correction and pressure correction of the count value N can be performed at the same time.

As described above, according to the present invention, two measuring chambers are formed by one measuring membrane, and the spring force of the snap action actuating means is accumulated according to the movement of the measuring membrane, and the first sliding contact piece Since the switching valve is switched by a snap action when the sliding contact between the first sliding contact piece and the second sliding contact piece is broken, the gas flow rate is stabilized without pulsation, and the flow meter can be made smaller. be able to. In addition, since the inlet and outlet valve holes of both metering chambers are arranged in a straight line, the gas flow path is simple and pressure loss can be suppressed, and the piping route can be simplified, reducing piping work. It becomes easier.

[Brief explanation of the drawing]

FIG. 1 is a sectional view of one embodiment of the present invention, FIG. 2 is a perspective view of the vicinity of the first operating rod 11 and second operating rod 12, and FIGS. 3 and 4 are the same as FIG. 1 showing the operating state. 5 is a perspective view of another embodiment of the present invention, FIG. 6 is a front view of another embodiment of the present invention, FIG. 7 is a front view showing the operation progress of FIG. 6, FIG. 8 is a graph showing the spring force F1 exerted by the compensation spring 50 of FIG. 7 on the first operating rod 11, and FIG.
A graph showing the spring force F2 that the compensation spring 51 in the figure acts on the first operating rod 11, FIG.
A graph showing the resultant force F of spring forces F1 and F2 of 0.51, FIG. 11 is a sectional view of another embodiment of the present invention,
FIG. 12 is a sectional view of another embodiment of the present invention, and FIG.
The figure is a sectional view taken along the cutting plane line - in FIG. 12, and FIG. 14 is a sectional view of another embodiment of the present invention. 1... Housing, 2... Metering membrane, 3, 4... Metering chamber, 5a, 6a... Inlet valve hole, 5b, 6b... Outlet valve hole, 10... Switching valve, 11... First operation rod,
12...Second operating rod, 14...Counter, 15,
16... Drive rod, 17... Valve body, 18, 19...
Connection rod, 23... first sliding contact piece, 24... second sliding contact piece, 25... torsion spring, 26... drive rod operating means, 50, 51... compensation spring, 75... compression spring.

Claims (1)

[Claims] 1. It has two measuring chambers separated by a single measuring membrane, and the measuring membrane can be moved toward each measuring chamber, and each measuring chamber has a gas inlet valve hole and an outlet valve. A casing each having holes, when the inlet valve hole of one metering chamber is open, the outlet valve hole of one metering chamber is closed, the inlet valve hole of the other metering chamber is closed, and the other metering chamber is closed. a switching valve for opening an outlet valve hole of the metering chamber, the switching valve comprising: a pair of drive rods movably extending between the inlet valve hole and the outlet valve hole of both measuring chambers; fixed to both ends of the drive rod; a valve body for blocking the inlet valve hole and the outlet valve hole, and a drive rod having both ends connected to both ends of the pair of drive rods with a pin, and at a position shifted to one side from the center position of both drive rods. a switching valve including a pair of connecting rods pivotally supported on a housing so as to be swingable around an axis perpendicular to the axis of the switching valve; an operating rod, a second operating rod that is movable in a direction intersecting the first operating rod, a first sliding contact piece that is fixed to the first operating rod and has sliding contact surfaces at both ends in the movement direction of the second operating rod; a second sliding contact piece fixed to the second operating rod and capable of slidingly contacting both sliding contact surfaces of the first sliding contact piece; The second sliding contact piece is biased by a spring toward the sliding contact surface, and when the first operating rod is on the other side in the moving direction, the second sliding contact piece is biased toward the other sliding contact surface of the first operating rod. a snap action actuating means for spring-biasing the second actuating rod; a driving rod actuating means for moving the one drive rod in the movement direction of the second actuating rod in response to movement of the second actuating rod; A gas flow meter characterized by including a counter for detecting. 2. The gas flow meter according to claim 1, wherein at least a portion of the connecting rod from the other drive rod to the pivot position is comprised of a spring. 3 The snap action actuating means is the first
A patent claim characterized in that the screw spring gently surrounds an axis perpendicular to the movement direction of the operating rod and the second operating rod, and has both ends pin-coupled to the first operating rod and the second operating rod, respectively. The gas flowmeter according to item 1. 4. The snap action actuating means includes teeth formed on the first actuating rod and the second actuating rod along the direction of movement thereof, and an axis perpendicular to the direction of movement of the first actuating rod and the second actuating rod. Claim 1, characterized in that it includes a pair of gears that are individually rotatably supported and mesh with the teeth, and a helical spring that surrounds the shaft and connects the gears. Gas flow meter as described. 5. The snap action actuating means includes a pair of compensating springs that apply forces in opposite directions along the direction of movement of the first actuating rod, and the spring force of each compensating spring is independent of the displacement of the metering membrane. 2. The gas flow meter according to claim 1, wherein the gas flow meter is selected so that the force acting on the metering membrane is substantially constant. 6. The snap action actuating means gently surrounds an axis perpendicular to the moving direction of the first actuating rod and the second actuating rod, and both ends thereof are pin-coupled to the first actuating rod and the second actuating rod, respectively. and a spring that applies a force to the first actuating rod that is opposite to the spring force acting on the first actuating rod of the torsion spring, and the spring force of each spring is independent of the displacement of the metering membrane. 2. The gas flow meter according to claim 1, wherein the gas flow meter is selected so that the force acting on the metering membrane is substantially constant. 7. The gas flowmeter according to claim 1, wherein the drive rod actuating means spring-biases the one drive rod in the direction of movement in response to movement of the second actuation rod. 8. The driving rod actuating means includes a leaf spring portion having one end fixed to the second actuating rod at right angles to the direction of movement thereof, and one end portion pin-coupled to the other end of the leaf spring portion and the other end fixed to the second actuating rod at right angles to the moving direction thereof. 9. A gas flowmeter according to claim 8, further comprising a rigid portion pin-coupled to the drive rod of the gas flowmeter. 9 A through hole extending in the moving direction of the first operating rod is formed in the first sliding contact piece, and the other sliding contact piece, which is displaceably inserted through the through hole, is connected to the first sliding contact piece by means of a bimetal.
2. The gas flow meter according to claim 1, wherein the gas flow meter is adapted to be displaced in the direction of movement of the operating rod. 10 A through hole extending in the moving direction of the first operating rod is formed in the first sliding contact piece, an airtight space that is expandable and contractible in the moving direction of the first operating rod is provided in the metering membrane, and the transparent 2. The gas flow meter according to claim 1, wherein another sliding contact piece that is displaceably inserted through the hole is displaced in response to expansion and contraction of the space. 11. The gas flow meter according to claim 10, wherein the space is maintained at a reduced pressure lower than atmospheric pressure. 12. The gas flowmeter according to claim 10, characterized in that gas is sealed in the space.