JPH11111131A - Flow switch - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a flow switch which has a simple structure and high durability, can be applicable to a wide range, and manufactured at low cost. SOLUTION: The base end part of an elastic material 2 is fixed in the inner wall of a flow pipe 1 through which a fluid flows while the other free end part of the elastic material is installed on the downstream side of the fluid in the flow pipe 1, a flow rate sensing body 4 which deflects the cantilever type elastic material by lift which is generated by the fluid flowing in the flow pipe, a magnet 5 is installed in the flow sensing body or near the body, and magnetism sensors 6a, 6b which are operated due to the approaching movement of the magnet and consequently whose output signals are reversed are installed in the outside of the flow pipe.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flow switch for a device for issuing an alarm when an excessive flow rate or an interruption occurs.

[0002]

2. Description of the Related Art For the purpose of knowing whether the flow rate of a fluid flowing in a pipe is normal or not, a so-called flow switch that switches an electric switch when the flow rate deviates from a normal range is widely used. For example, in the cooling water line of the device, a switch is set when the flow rate of the cooling water falls below the allowable value to prevent the temperature of the device from rising due to the cooling water flow below the allowable value and being damaged by overheating. A flow switch that is turned on is often used.

In this case, if the device is automatically stopped when the switch is turned on, it is possible to prevent the device from being damaged. In addition, a buzzer can be sounded by a switch to notify the operator of an abnormality of the cooling water.

[0004] From the purpose of use of the flow switch, malfunctions or malfunctions may cause serious losses, and it is therefore desired to satisfy the following conditions. 1. 1. The structure is simple and hard to break down. 2. High durability and long-term use. It is high in strength and does not break even when the flow velocity of the fluid becomes excessive. In practice, it is desirable that the fluid satisfies the following conditions. 4. 4. Applicable fluid temperature and pressure range is wide. 5. The pressure loss generated when a fluid flows inside is small. 6. Even if solid particles or contaminants are present in the fluid, malfunction is unlikely to occur. Low manufacturing cost At present, many types of flow switches are used, but few of them satisfy all of the above conditions 1 to 7, and a suitable one is selected and used depending on the purpose.

[0005] For example, the magnet shown in FIG.
This is a type in which a magnetic sensor 14 is attached to an area flowmeter in which a float 12 enclosing a float 1 is provided in a tapered tube 13, and the output signal of the magnetic sensor is inverted when the position of the float approaches the magnetic sensor. In this type, when the flow rate increases rapidly, the float collides with the upper stopper 15a and is easily broken, and does not meet the above condition 3.

Also, the magnetic sensor has a so-called self-holding type in which, after the float approaches and the output signal is inverted, the output is maintained as it is if the float movement direction is positive, and the output is inverted again if the float movement direction is opposite. Must be used, which increases costs.

In FIG. 1, reference numeral 15b denotes a lower stopper. The example of FIG. 8 is a so-called impeller type,
The rotation speed of the impeller 17, which is substantially proportional to the flow velocity of the fluid flowing through the inside 6, is detected.
The switch is inverted. There are various methods for detecting the rotation speed of the impeller, and FIG.
A method of detecting the number of rotations with the magnetic sensor 20,
FIG. 10 shows the light emitting element 21a and the light receiving element 21b facing each other,
In this method, the light to the light receiving element is blocked by the blades, and the number of rotations is detected by the light receiving element. In the figure, reference numerals 22a and 22b denote light transmitting portions provided on the tube.

In the impeller type, in any failure, the output indicating the number of revolutions of the impeller becomes zero and becomes the same output as the stop of the flow. Although it is safe and is preferable in terms of safety, it requires a power supply and has an electronic circuit, which increases the cost. Further, there are disadvantages such as a relatively large pressure loss and a short life due to wear of the rotating shaft or the bearing.

FIG. 11 shows an example of a so-called flapper type in which a flapper 24 supported rotatably by a hinge is attached to an outlet of a nozzle 23 provided in a flow path pipe, and is rotated by being pushed by a fluid ejected from the nozzle 23. The flow rate is detected from the rotation angle of the flapper 24, and a magnetic method and an optical method are often used as a method of detecting the rotation angle of the flapper, similar to the impeller method.
The flapper is provided with a weight 25 for repositioning. This method is widely used because the structure is simple and the cost is low. However, foreign matter in the fluid is likely to accumulate on the hinge portion 26 of the flapper to cause malfunction, and the pressure loss at the nozzle portion is relatively large. In the case of excessive flow or sudden increase in flow,
There are problems such as the flapper may be bent and the hinge may be broken, and improvement is desired.

[0010]

An object of the present invention is to realize a flow switch satisfying all the above-mentioned conditions.

[0011]

In order to achieve the above object, a flow switch according to the present invention has a base end fixed to an inner wall of a flow pipe through which a fluid flows, and a flow path in which a free end is located downstream of the fluid. At the free end of the elongated cantilevered elastic material disposed in the pipe, a flow rate sensing element is provided in which a lift is generated by a fluid flowing in the flow path pipe and the cantilever elastic material is bent by the lift, and the flow rate sensing element or A magnet is provided in the vicinity thereof, and a magnetic sensor which is activated by the proximity of the magnet and inverts the output signal is provided outside the channel tube.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As shown in FIG. 1, an upstream base end of an elongated elastic flexible material made of a plate or a wire is attached to an upper inner wall of a non-magnetic flow pipe 1 through which a fluid flows through a bracket 3 or the like. To form a cantilevered elastic member 2, and the downstream free end of the cantilevered elastic member 2 elastically contacts or approaches or faces the lower inner wall of the flow pipe,
And a shape in which lift is generated by the flow of fluid at the free end,
The flow rate sensing element 4 made of a non-magnetic material having a structure is fixed.

In the embodiment shown in FIG. 1, the flow sensing element 4 is a plate-shaped object having a vertically asymmetrical spindle-shaped cross section, such as an airplane wing, but a flat plate having an elevation angle as shown in FIG. Any object can be used as long as it generates a force perpendicular to the cantilevered elastic member due to the flow, such as a curved plate as described above.

When a fluid flows, a lift is generated in the flow rate sensing element 4, so that a bending stress acts on the cantilevered elastic member, and FIG.
As shown by the imaginary line in FIG. 3, the cantilevered elastic member 2 is bent and the flow rate sensing element is displaced upward. The displacement of the flow sensing element at this time depends on the lift generated in the flow sensing element, that is, the flow rate. The relationship between the amount of displacement and the flow rate is determined by the rigidity of the spring, the size, weight, cross-sectional shape, etc. of the flow rate sensing element, and may be selected at the design stage so as to be suitable for use conditions.

A magnet 5 is attached to or near the flow rate sensing element 4, and a magnetic sensor 6 is provided outside the flow pipe so as to be sensitive to the approach of the magnet. There are various types of magnetic sensors, such as a reed switch, a Hall element, and a magnetoresistive element, which can be used properly depending on the purpose.

If the strength of the magnet 5 and the distance between the magnet 5 and the magnetic sensor 6 are appropriately selected so that the output of the magnetic sensor is reversed before and after the displacement of the flow rate sensing element corresponding to a specified flow rate, The device of the present invention can be used as a flow switch for any specified flow rate value. Further, if the mounting position of the magnetic sensor is made variable, the specified flow rate value can be made variable within a certain range.

The arrangement of the magnet and the magnetic sensor includes a system in which the two flow away from each other when the flow sensing element 4 is displaced due to an increase in the flow as shown in FIG. 1, and a system in which both are moved away as shown in FIG. You can choose one. For example, in the case of a so-called breakage alarm switch in which the output signal is inverted when the flow rate approaches 0, it is desirable for safety that the output becomes the same as the alarm state (flow rate 0) when the magnetic sensor becomes defective and becomes insensitive to magnetism. Therefore, when the magnet is near the lowest point in the method of FIG. 1, the magnetic sensor is insensitive,
The sensor may be designed to be sensitive to a slight elevation of the magnet.

In the above embodiment of FIGS. 1 to 3, the free end on the downstream side of the cantilevered elastic member 2 elastically contacts, approaches, or faces the lower inner wall of the flow pipe.
In some cases, the cantilevered elastic material is substantially parallel to the direction of the fluid flow.

Although the above-described first to third embodiments are examples in which the lift acts upward, the lift may be generated downward as in the embodiment of FIG.
When the flow of the fluid is in the vertical direction as in the embodiment of the present invention, the fluid may be generated in the horizontal direction.

FIG. 6 shows an embodiment in which the method of FIG. 1 and the method of FIG. 2 are used together to output an alarm signal at two different flow rates. That is, this is an example of a flow switch that can output both a disconnection alarm for detecting that the flow rate has become substantially zero and an excessive flow rate alarm for detecting that the flow rate has exceeded a specified value.

In this embodiment, the magnet 5 is built in the spindle-shaped cross-section flow sensing element 4 which generates upward lift by the flow, and the magnetic sensors 6a and 6b are provided on the upper and lower parts of the outside of the flow pipe. is there.

A stopper 7 is provided above and below the inner wall of the flow pipe.
When the flow rate is 0, the flow sensing element 4 is adjusted so as to contact the lower stopper 7b, and when the flow rate exceeds a specified value, the flow sensing element 4 contacts the upper stopper 7a.
A and 7b also serve to limit the amount of bending of the cantilevered elastic member and to prevent the cantilevered elastic member from being broken by fatigue. Reference numerals 8a and 8b denote screw shafts for adjusting the positions of the magnetic sensors 6a and 6b, and reference numerals 9a and 9b denote bearings, 10a and 1b.
0b indicates a tightening nut.

The strength of the magnet, the sensitivity of the magnetic sensor, and the position are such that the upper sensor 6a is turned off when the flow sensing element contacts the lower stopper 7b, and the lower sensor 6b is turned off when the flow sensing element contacts the upper stopper 7a. Adjust to
That is, as shown in Table 1 below, when the flow rate becomes 0, the upper sensor 6a reverses from ON to OFF and outputs a disconnection alarm, and when the flow rate exceeds the specified value, the sensor 6b switches from ON to OF.
Inverts to F, outputs an excessive flow rate alarm, and operates as a flow switch that outputs two alarms.

[0024]

[Table 1] By increasing the number of sensors and selecting the mounting position,
It is also possible to output three or more alarms.

[0025]

As described below, according to the present invention, it is possible to realize a flow switch which satisfies all the items described in the prior art and its problems and has the following advantages not found in the conventional one. 1. Compared with the conventional flow switch (FIGS. 5 to 9), the structure is simple and it is hard to break down. 2. Since there is no rotating shaft or sliding part, and the main force acting on the cantilevered elastic member is tension, it has high durability and can withstand long-term use. 3. The drag (fluid parallel to the flow) of the fluid acting on the flow rate sensing element is relatively small, and its displacement is limited by the stopper.
Withstands excessive flow rates. 4. All the structures in the flow path can be made of parts having high heat resistance, and if a strong magnet is used and the magnetic sensor is separated from the flow path to form a heat insulating structure, it can be applied to a fluid having a high temperature. 5. Since the cantilevered elastic member is substantially parallel to the flow and the drag (force parallel to the flow) acting on the flow rate sensing element is small, the pressure loss is smaller than that of a conventional flow switch (FIGS. 5 to 9). 6. Even if foreign matter is contained in the fluid, operation failure is unlikely to occur because there are almost no structures in the flow path that obstruct the flow. 7. Fewer parts compared to conventional flow switches,
In addition, the cost is low because the flow path can be manufactured with a pipe. In addition, since the specifications of the flow switch can be changed widely by changing the shape and dimensions of the flow rate sensing element and the rigidity of the cantilevered elastic member, the wide application range is also a great advantage.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a first embodiment of a flow switch according to the present invention.

FIG. 2 is a sectional view showing a second embodiment of the flow switch according to the present invention.

FIG. 3 is a sectional view showing a third embodiment of the flow switch according to the present invention.

FIG. 4 is a sectional view showing a fourth embodiment in which the lift of the flow switch according to the present invention acts downward.

FIG. 5 is a sectional view showing a fifth embodiment in which the lift of the flow switch according to the present invention acts horizontally.

FIG. 6 is a sectional view showing a sixth embodiment of the flow switch having two pairs of magnetic sensors according to the present invention.

FIG. 7 is a sectional view showing a conventional area flow meter provided with a magnetic sensor.

FIG. 8 is a cross-sectional view showing a conventional impeller flow meter provided with an electronic circuit.

FIG. 9 is a cross-sectional view showing a conventional impeller flow meter provided with a magnetic sensor.

FIG. 10 is a cross-sectional view showing a conventional impeller flow meter provided with a light emitting element and a light receiving element.

FIG. 11 is a sectional view showing a conventional flapper type flow meter.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Flow path pipe 2 Cantilever elastic member 3 Bracket 4 Flow rate sensing element 5 Magnet 6 Magnetic sensor 6a Upper magnetic sensor 6b Lower magnetic sensor 7a Upper stopper 7b Lower stopper 8a, 8b Screw shaft 9a, 9b Screw shaft bearing 10a, 10b Tightening nut

Claims (1)

[Claims] 1. An elongated cantilevered elastic material having a proximal end fixed to an inner wall of a flow pipe through which a fluid flows and disposed in the flow pipe such that a free end is located downstream of the fluid. A lift is generated by a fluid flowing in the flow path pipe, and a flow sensing element is provided to bend the cantilever elastic material by the lift, and a magnet is provided at or near the flow sensing element, and the magnet is actuated by the proximity of the magnet. A flow switch provided with a magnetic sensor whose output signal is inverted when the magnetic sensor is inverted outside the flow path tube.