JPH0629694Y2 - Water gauge - Google Patents

Description

[Detailed Description of the Invention] (a) Technical Field The present invention relates to a water level gauge, and more specifically, converts a water level change of groundwater, a river, a reservoir, etc. into an electric signal based on the water pressure applied to a pressure receiving portion. It is related to the water level gauge that is detected by.

(b) Prior Art Conventionally, a water pressure gauge has been used to measure the water level by detecting the water pressure. This water pressure gauge consists of a filter, a pressure receiving part, and converts the amount of strain generated in the diaphragm, which is the pressure receiving part, into an electrical output by a strain gauge attached to the diaphragm or a beam connected to the diaphragm. It is designed to be taken out.

However, the water pressure gauge configured as described above has a problem that it is difficult to accurately detect a low pressure of 1 kg / cm ² or less due to its structure, and the output is affected by fluctuations in atmospheric pressure. There are difficulties.

On the other hand, the movement of the bellows lid of the first bellows, which is displaced by the fluid to be measured, is transmitted to the second bellows through the fluid guided by the conduit, and the displacement of the bellows lid of the second bellows is further linked to the link mechanism and the gear. A hydraulic water level gauge has been proposed which is configured to change the rotation of a pointer through a mechanism.

As described above, this hydraulic water level gauge is a method of mechanically transmitting the movement of the first bellows to the pointer, so it has the advantage of not requiring a power source, but it has a mechanical backlash and high precision. It is difficult to obtain water quality, and it cannot be said that durability is inevitably sufficient.Because electric output is not obtained, it is not possible to measure at a point far from the installation point of the water level gauge, and in addition, it is small. There are drawbacks such as difficulty in realization.

(c) Purpose The present invention has been made to solve the above-mentioned drawbacks of the prior art. The purpose of the present invention is to reduce the size and capacity and to eliminate the influence of atmospheric pressure. An object of the present invention is to provide a water level meter that has good linearity and can obtain an electric signal corresponding to the water level, and thus can obtain measurement data of the water level at a remote location apart from the installation location of the water level gauge.

(d) Structure In order to achieve the above-mentioned object, the present invention has a main body case part having an atmospheric pressure chamber communicating with the atmosphere at one end and a water pressure chamber communicating with the fluid to be measured at the other end, and a bellows lid. A first bellows whose free end side is closed to the atmospheric pressure chamber and whose base portion is fixed to the main body case portion; and a free end side closed to another hydraulic bellows lid is to the hydraulic chamber and the base portion is the main body case. A second bellows or a pressure receiving surface fixed to the water pressure chamber and a peripheral edge fixed to the main body case portion; a bellows lid of the first bellows; and a second bellows. And a connecting member for connecting the bellows lid or the diaphragm, and a length that is limited to the inner diameter of the main body case portion, and a force in the bending direction is applied to the free end side through the connecting member so that the base end is The main body case A strain-flexing plate disposed in the main body case portion in a state of being fixed to the strain-bearing portion, and a strain gauge attached to the surface of the strain-flexing plate, which are applied to the second bellows or the diaphragm. The pressure of the fluid to be measured is converted into an electric signal by the strain gauge to obtain a signal corresponding to the water level.

Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings. FIG. 4 is a front sectional view of a first embodiment showing the principle configuration of the present invention.

In FIG. 4, the main body case portion is composed of a combined body of a cylindrical bellows case 41 and a strain-flexing portion case 42, and a pipe 43 for introducing air is connected to the central portion of the closed end surface of the bellows case 41. A water pressure side bellows 44 serving as a second bellows is arranged so as to be exposed from the strain-flexing part case 42 at the center of the bottom surface of the strain-flexing part case 42, and its base end is watertight on the lower surface of the strain-flexing part case 42. Installed on. Further, an atmospheric pressure side bellows 45 as a first bellows is arranged in the bellows case 41, a base end of which is watertightly attached to a ceiling surface of the strain-flexing part case 42, and a bellows lid 46 is provided at a free end thereof. It is also watertightly mounted. On the other hand, a free end (lower end) of the water pressure side bellows 44 is also watertightly fitted with a bellows lid (pressure receiving plate) 47, and a central portion of the inner surface of the bellows lid 47 and a central portion of the inner surface of the bellows lid 46 are connected to each other. They are integrally connected by a connecting rod 48 as a member. Therefore, the bellows lid 46 responds to the vertical movement of the bellows lid 47. A flexure plate 49 is arranged in a space surrounded by the bellows 44, 45 and the flexure case 42, and the fixed end of the flexure plate 49 is integrally fixed to the inner surface of the flexure case 42. The movable end (free end) is fixed to the connecting rod 48. A strain gauge 50 is attached to the portion of the flexure plate 49 where the bending stress is maximized by means such as adhesion or vapor deposition. Although not shown, lead wires for supplying a bridge power supply to the strain gauge 50 from the outside or for leading out the strain detection output to the outside are inserted into the pipe 43 or wired along the pipe 43. To be done. In addition, an inert gas is sealed in the strain-flexing part case 42 to secure the long-term rustproof effect and moistureproof property of the strain gauge 50.

In order to prevent the movement of the bellows 44 from being impeded or adhered to the water pressure side bellows 44, it is common to surround the circumference with a filter or the like described later.

In the above configuration, when measuring the water level (water depth), the main body case is immersed in water such that the upper end of the pipe 43 is exposed from the water level (WL). Then, the water pressure is applied to the bellows lid 47 to compress the bellows 44 and push up the bellows lid 46 via the connecting rod 48. As the connecting rod 48 rises, the strain-flexing plate 49 bends, strain (expansion or compression) occurs in the strain gauge 50 according to the amount of this bending, and an electric signal is output from the output end of the Wheatstone bridge assembled with this strain gauge. You can take it out. From this electric signal, the water depth from the water surface to the position of the bellows lid 47 can be known. At this time, the atmosphere is introduced into the bellows case 41 through the pipe 43, and the pressure inside the bellows case 41 is made equal to the atmospheric pressure. Therefore, the differential pressure between the water pressure applied to the water pressure side bellows 44 and the atmospheric pressure applied to the atmospheric pressure side bellows 45 appears as the displacement of the connecting rod 48, and the strain plate 4
9 will be bent.

According to the first embodiment configured and operating in this way,
Since the water pressure side bellows 44 and the atmospheric pressure side bellows 45 have the same shape and performance, the influence of the atmospheric pressure can be completely removed.

Further, since the strain generating plate 49 is bent by the connecting rod 48 that connects the two bellows 44, 45, and the strain gauge 50 that expands and contracts according to the amount of bending is used to convert the signal into an electric signal. It responds accurately to low pressure and has good linearity. In addition, there is no mechanical rattling,
Since the strain gauge 50 is enclosed by the bellows 44 and 45 and disposed inside the strain-flexing part case 42 filled with an inert gas, the strain gauge 50 is not deteriorated due to oxidation or moisture absorption, and is capable of detecting stable water pressure for a long time. Is possible. Since the measurement data obtained from the strain gauge 50 is an electric signal corresponding to the water level, it can be transmitted to a remote place via a lead wire, and water levels at a plurality of places can be centrally monitored at one place. It will be possible.

1 and 2 are a front sectional view and a side sectional view showing the structure of a second embodiment of the present invention.

The second embodiment has a basic configuration in common with the first embodiment, but in particular, the connecting structure between the strain-flexing plate and the connecting rod is largely different, and the second embodiment is more specific. There is a difference.

The main body case portion includes a cable pull-in case 1, a seal case 2 into which the case 1 is fitted at one end, a partition member 3 coupled to the other end of the seal case 2, and a stand member connected to the partition member 3. Distortion part case 4, cylindrical filter 5 connected to this flexure part case 4, this filter 5
And a cover 6 that protects a bellows (described later) located immediately above the bellows. The main body case section has the partition member 3 as a boundary, and the atmospheric pressure chamber B is provided above the partition member 3.
Is formed, and a hydraulic chamber A is formed in the lower part thereof.

The upper portion of the cable pull-in case 1 is tapered, and a holding metal fitting (so-called cable gland) 8 for pressing and holding the cable 7 is screwed into a female screw portion formed on the inner peripheral surface, and the lower end of the holding metal fitting 8 is waterproof. The packing member 9 is provided. A nylon pipe 10 and a signal line 11 for introducing outside air into the atmospheric pressure chamber B are inserted into the cable 7. The signal line 11 is connected to an arrester 12 for lightning protection in the case 1 and is also connected to a strain gauge described later. The top of case 2 is arrester 12
Has a base portion 14 to which the attachment substrate 13 is attached, and an opening end portion of the nylon pipe 10 and a lead wire are inserted into a hole formed in the center portion thereof. A hermetic seal 15 for waterproofing is provided at the upper end of this hole. The base portion 14 is sealed to the case 1 by an O-ring 16 and prevents water from entering from the outside through the screwed portion between the cases 1 and 2. A guide plate 18 for guiding the lead wires 17 is attached to the lower portion of the base portion 14 by means of screws. A part of the outer circumference of the base 14 is threaded, and the lower end of the case 1 is screwed in.

A base end of an atmospheric pressure side bellows 20 as a first bellows having a bellows lid 19 at a free end (an upper end in the figure) is watertightly fixed to the upper surface of the partition member 3 by welding or the like. A water pressure side bellows 22 as a second bellows having a bellows lid 21 at a free end (lower end in the figure) is watertightly fixed to the rim of the strain-flexing portion case 4 by welding or the like. A connecting rod 23 as a pipe-shaped connecting member is coaxially connected to the bellows lids 19 and 21, and a substantially middle portion thereof is cut so as to penetrate in the diametrical direction. A strain-flexing plate 24 is arranged in a state of penetrating this cut portion, its base end is fixed to the lower surface of the partition member 3, and its free end is connected to a drive member 25 extending outward from the connecting rod 23. It is connected. The joint between the partition member 3 and each of the case 2 and the strain-flexing part case 4 is hermetically connected by welding or the like. Further, the bellows 20 and 22 are filled with an inert gas. The filling port 26 is sealed after being filled with this inert gas. Further, although not shown, a strain gauge is attached to the surface of the strain plate 24.

Next, the operation of the second embodiment having the above configuration will be described.

While pulling the cable 7 into water such as a dam, the main body case is lowered to the desired water level detection depth. Water at that depth enters the hydraulic chamber A through the filter 5, and the pressure obtained by adding the atmospheric pressure to the water pressure corresponding to the water depth is applied to the bellows lid 21 of the bellows 22. As a result, the water pressure chamber side bellows 22 contracts due to the pressure and pushes up the connecting rod 23. At this time, since the outside air is introduced into the atmospheric pressure chamber B in which the atmospheric pressure chamber side bellows 20 is arranged through the nylon pipe 10, the connecting rod 23 is equal to the difference between the pressure applied to the bellows lid 21 and the atmospheric pressure. Is displaced. This displacement is transmitted to the free end of the strain-flexing plate 24 via the driving member 25 to bend the strain-flexing plate 24, and the amount of strain is converted into an electric signal by a strain gauge (not shown). The strain amount is proportional to the pressure head, that is, the water depth from the water surface to the bellows lid 21 of the water pressure side bellows 22.

Therefore, if a bridge power supply is supplied to the input end of the Wheatstone bridge composed of strain gauges, an electrical signal corresponding to the water level of the desired depth is output from the output end of the bridge via the lead wire 17, the cable 7, etc. Can be derived to.

According to the second embodiment, not only all the effects obtained by the first embodiment are exhibited, but also the following effects are added.

That is, the strain-flexing plate 24 has a length close to the inner diameter of the case 4, the base end is fixed to a portion near the inner wall surface of the case 4, and the free end is attached to the driving member 25 in the vicinity of the facing portion of the case 4 that is offset by 180 °. Since they are connected to each other, the length of the strain-flexing plate 24 can be about twice as long as that of the strain-flexing plate 49 of the first embodiment without increasing the diameter of the case 4, and the detection sensitivity and the pressure can be increased accordingly. -Strain characteristics (or pressure-strain output characteristics)
The linearity of can be greatly improved. In other words,
While maintaining the same detection sensitivity and non-linearity, the water level gauge can be significantly reduced in size, weight, and cost.

The bellows 22 on the water pressure chamber side includes the cover 6 and the filter 5.
Since it is surrounded by, even if it is installed in an environment where water contains foreign matter such as sludge, rocks, dust, etc., these foreign matter are prevented from entering the hydraulic chamber A by the filter 5. Therefore, there is no inconvenience that the displacement of the bellows 22 is hindered due to the foreign matter being caught between the bellows 22 or adhering thereto. Further, since the cover 6 is provided, damage to the bellows 22 is prevented even if the water level gauge collides with the ground floor, structures, fluids, etc. during installation or during measurement.

FIG. 3 is a sectional view showing the construction of the main part of the third embodiment of the present invention. The present embodiment is different from the first and second embodiments in that a diaphragm 30 is used as a water pressure side pressure receiving portion instead of the bellows. The bellows has a smaller spring constant and better linearity of the pressure-displacement characteristic than the diaphragm, and is suitable for downsizing, but it has a fold and the impurities that enter the hydraulic chamber A are easily attached. Therefore, it can be said that the diaphragm is more suitable for use in a place where the environment is poor. The embodiment of FIG. 3 is intended for such an application, and deterioration of the characteristics can be suppressed even in long-term use. The cover 31 is provided with a large number of water passage holes so as to protect the diaphragm 30 from an impact and allow water to freely enter the water pressure chamber A.

The present invention is not limited to the embodiments described above and shown in the drawings, and various modifications can be made without departing from the spirit of the invention.

For example, although the arrester 12 is provided in the second embodiment,
This is not mandatory. However, when used in an area where lightning occurs, it is desirable to use a water level gauge having a built-in arrester 12 because there is a risk of lightning strikes on the water level gauge.

Further, when used in clean water, the filter may be omitted.

Moreover, although the above description has described the detection of the water level, the object to be measured is not limited to this, and can also be applied to the detection of the liquid level of liquids such as chemicals and liquid fuel.

(e) Effects As described in detail above, according to the present invention, it is possible to reduce the size and capacity, and to almost completely eliminate the influence of atmospheric pressure, and also to improve the linearity and detection sensitivity, and to improve the water level. It is possible to provide a water level meter that can obtain a corresponding electric signal and thus can obtain water level measurement data at a remote location apart from the installation location of the water level gauge.

[Brief description of drawings]

FIG. 1 is a front sectional view showing the constitution of a second embodiment of the present invention, FIG. 2 is a side sectional view of the same embodiment, and FIG. 3 is a constitution of a main part of a third embodiment of the present invention. FIG. 4 is a sectional view showing a schematic configuration of a first embodiment of the present invention. 1 ... Cable entry case, 2 ... Sealing case, 3 ... Partition member, 4 ... Strain element case, 5 ... Filter, 6,31 ... Cover, 10 ... Nylon pipe, 14 ... Base part, 19, 21, 46, 47 ... Bellows lid, 20, 45 ... Atmospheric pressure side bellows, 22, 44 ... Water pressure side bellows, 23, 48 ... Connecting rod, 24, 49 ... Strain Plate, 25 ... Driving member, 30 ... Diaphragm, 41 ... Bellows case, 42 ... Strain element case, 43 ... Atmosphere introduction pipe, 50 ... Strain gauge.

Claims (1)

[Scope of utility model registration request] 1. A main body case portion having an atmospheric pressure chamber communicating with the atmosphere at one end and a hydraulic chamber communicating with the fluid to be measured at the other end, and the free pressure side closed by a bellows lid is the atmospheric pressure chamber. A first bellows whose base portion is fixed to the main body case portion and a second bellows whose free end side closed by another bellows lid is projected to the hydraulic chamber and whose base portion is fixed to the main body case portion A diaphragm whose surface faces the water pressure chamber and a peripheral edge of which is fixed to the main body case portion, and a connection which connects the bellows lid of the first bellows and the bellows lid of the second bellows or the diaphragm. A member and a length that is limited to the inner diameter of the main body case, and a force in the bending direction is applied to the free end side through the connecting member, and the base end is fixed to the main body case. Body Over scan and strain-generating plate disposed within unit, comprising a affixed by strain gauges on the surface of the strain generating plate,
A water level meter configured to obtain a signal corresponding to a water level by converting a pressure of a fluid to be measured applied to the second bellows or the diaphragm into an electric signal by the strain gauge.