JP3941585B2 - Flow measuring device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a flow rate measuring device for measuring a flow rate of gas or the like.
[0002]
[Prior art]
A conventional flow measuring device of this type will be described with reference to FIG. In the figure, a flow rate detecting means 2 such as an ultrasonic type is provided in a part of the fluid passage 1 to measure the flow rate. When there is a periodic fluctuation in the flow, the flow rate measurement value varies depending on the measurement timing. For example, in a gas meter that measures household gas consumption, pressure fluctuation occurs when a gas engine is operated nearby. For this reason, in order to buffer the pressure fluctuation, a pulsation absorbing device 4 having a valve body 3 is provided to reduce the pulsation level.
[0003]
[Problems to be solved by the invention]
However, the conventional flow rate measuring device has a drawback that the flow turbulence caused by the pulsation absorbing device and the uneven flow velocity distribution deteriorate the accuracy of the flow rate measurement.
[0004]
[Means for Solving the Problems]
In order to solve the above-mentioned problems, the present invention suppresses the flow in the reverse direction to the fluid passage, the flow rate detecting means for detecting the flow rate of the fluid passage, the upstream side or the downstream side of the fluid passage, and the forward direction. Has a pressure fluctuation control valve that gives a flow of diffusing fluid, and the valve body of the pressure fluctuation control valve is provided with blades. According to the above invention, the flow in the reverse direction is prevented to suppress pressure fluctuations, and an accurate flow rate is obtained without causing flow disturbance even in the absence of pulsation.
[0005]
DETAILED DESCRIPTION OF THE INVENTION
The present invention relates to a fluid passage, flow rate detecting means for detecting the flow rate of the fluid passage, and a flow that flows in the forward direction from the center and diffuses to the upstream side while suppressing a reverse flow upstream of the fluid passage. The pressure fluctuation control valve is configured to absorb the pulsation when there is pulsation, and accurately measure the flow rate without causing flow turbulence even when there is no pulsation.
[0006]
Further, the pressure fluctuation control valve gives a swirl flow to the fluid, and the flow stability is enhanced by the swirl flow.
[0007]
Further, the pressure fluctuation absorbing valve is provided with a blade, and a swirl flow is given by the blade to stabilize the flow.
[0008]
A fluid passage; and a flow rate detecting means for detecting a flow rate of the fluid passage; and a pressure fluctuation control valve for suppressing a reverse flow and allowing a fluid to pass in the forward direction on the downstream side of the fluid passage. The effect of flow turbulence at the pressure fluctuation control valve on the flow measurement accuracy is small.
[0009]
In addition, a communication flow path that bypasses the passage of the pressure fluctuation control valve is provided. When the flow rate is small, the flow flows through the communication flow path, so that the flow fluctuation due to the pressure fluctuation control valve is small.
[0010]
【Example】
Embodiments of the present invention will be described below with reference to the drawings.
[0011]
Example 1
FIG. 1 is a configuration diagram illustrating a flow rate measuring apparatus according to a first embodiment of the present invention. In FIG. 1, a flow rate detecting means 6 is provided in the fluid passage 5 to detect the flow rate of the passage. The flow rate detecting means 6 is arranged with ultrasonic transmitters / receivers 6a and 6b on the upstream side and downstream side of the flow, respectively, and the flow rate is determined from the time difference between the ultrasonic propagation time from upstream to downstream and the ultrasonic propagation time from downstream to upstream. The details will be described later. A pressure fluctuation control valve 7 including a valve seat 7a, a valve body 7b, and a spring 7c is provided upstream 5a of the flow rate detection means 6.
[0012]
Next, the operation will be described. In FIG. 1, the pressure fluctuation control valve 7 is provided on the upstream side of the flow rate detecting means 6, and is configured to be biased by a spring 7c against the weight of the valve body 7a to close the valve seat 7b. When the fluid flows in the forward direction, the valve body 7b is pushed downward against the force of the spring 7c to open the valve. When there is no flow, the valve body 7b closes the valve seat 7a with a spring 7c, but in the forward flow (in the direction of the arrow), the valve body 7b is pushed down by the pressure difference as shown in the figure to open the valve. As the forward flow increases, the valve opening increases further and the pressure loss does not increase significantly. When a flow in the reverse direction occurs due to the pressure fluctuation, the valve body 7 receives an upward force and strongly closes the valve seat 7a to stop the flow.
[0013]
In other words, when there is no average flow in the fluid passage or when the flow rate is small, the reverse flow caused by pressure fluctuation is prevented, and the forward flow is also suppressed because the valve opening is small. Therefore, the average flow rate can be calculated without greatly changing the value of the flow rate detection means 6. Further, when a large flow rate flows in the fluid passage, the differential pressure generated in the valve body 7b increases, so that the valve body 7b is displaced downward in the figure to increase the valve opening, thereby significantly increasing the pressure loss. There is no. If a pressure fluctuation occurs at this time, the valve opening degree is large and the effect of suppressing the pressure fluctuation is small, so that a flow rate error is generated. However, the average flow rate is large, and the error ratio is relatively small.
[0014]
In addition, when the opening degree of the valve body 7a becomes large too much, the stopper (not shown) which regulates the maximum opening degree can be attached.
[0015]
If the pressure fluctuation control valve 7 is provided on the upstream side of the flow rate detection means 6, the pressure fluctuation is suppressed at this portion, so that the influence of pulsation is further reduced on the flow rate detection means 6. The direction of the valve body 7b and the spring 7c can be freely selected.
[0016]
On the other hand, it is conceivable that the flow rate is changed and the flow rate accuracy is deteriorated by providing the valve body upstream. However, the fluid flows in from the valve seat 7a at the center of the flow path, and the fluid flows in a circumferential direction through the gap between the valve body 7b and the valve seat 7a, so that the influence on the flow rate detection hand is extremely small. In addition, the inlet 5a of the fluid passage 5 flows in with a flow velocity distribution that is biased by what is connected upstream (for example, a curved pipe), but is diffused when passing through the valve body 7b to detect the flow rate. The means 6 flows with a uniform flow velocity distribution.
[0017]
FIG. 2 shows details of the flow rate detecting means using ultrasonic waves. In FIG. 2, the 2nd transmitter / receiver 6b which transmits / receives with the 1st transmitter / receiver 6a is arrange | positioned in the flow direction. 8 is a flow rate calculation means for processing and calculating a signal based on the ultrasonic wave, and 9 is a transmission circuit, which drives the first transmitter / receiver 6a by the trigger means 10 toward the second transmitter / receiver 6b, that is, from upstream to downstream. Send sound waves. The amplifying circuit 11 amplifies the signal received by the second transmitter / receiver b, the amplified signal is compared with the reference signal by the comparison circuit 12, and after the signal equal to or higher than the reference signal is detected, the repeater 13 triggers again. Transmission is performed from the means 10, and the time after the above transmission / reception is repeated a predetermined number of times is obtained by the time measuring means 14 such as a timer counter.
[0018]
Next, the switching means 15 switches the transmission / reception of the first transmitter / receiver 6a and the second transmitter / receiver 6b to transmit an ultrasonic signal from the second transmitter / receiver 6b toward the first transmitter / receiver 6a, that is, from downstream to upstream. Is repeated as described above, and the time is counted. Then, the flow rate calculation means 8 obtains the flow value from the time difference in consideration of the size of the pipeline and the flow state.
[0019]
(Example 2)
FIG. 3 is a block diagram showing an embodiment of the present invention. In FIG. 3, a pressure fluctuation control valve 7 comprising a valve seat 7a and a valve body 7b is provided on the downstream side of the flow rate detecting means 6 provided in the fluid passage 5. ing.
[0020]
Next, the operation will be described. When there is no flow, the valve body 7b closes the valve seat 7a by its own weight, but in the forward flow (in the direction of the arrow), the valve body 7b is lifted as shown in the figure by the pressure difference and opens the valve. As the forward flow increases, the valve opening increases further and the pressure loss does not increase significantly. When a flow in the reverse direction is generated due to pressure fluctuation, the valve body 7 receives a downward force and, together with its own weight, strongly blocks the valve seat 7a to stop the flow.
[0021]
Since the pressure fluctuation control valve 7 is on the downstream side of the flow rate detection means 6, even if the flow is somewhat disturbed in this portion, the flow rate detection is not adversely affected.
[0022]
(Example 3)
4 shows the valve body 7b, FIG. 4 (a) is a front view, and FIG. 4 (b) is a plan view thereof. The valve body 16 has substantially the same action as the valve body 7b described above, but the flow is swirled by a plurality of blades such as the blade 16a. This swirl flow can stabilize the flow velocity distribution even for a flow with a significantly biased flow velocity distribution.
[0023]
Example 4
FIG. 5 shows the valve seat 17 provided with a communication channel 17a. When the flow rate is small, the fluid passes through the communication channel 17a and the position of the valve element 18 does not change, so the flow is extremely stable. In addition, when the valve body 18 is spherical, it has higher objectivity with respect to the center and is stable with respect to the flow. The communication channel 17 a may be provided in the valve body 18.
[0024]
The valve body is preferably lighter in order to increase the responsiveness. For this reason, it may be made of a material having a specific gravity as small as possible or hollow.
[0025]
According to the flow measurement apparatus in an embodiment of the apparent the present invention from the description of the following the following advantages.
[0026]
(1) Fluid and passage, the flow and the flow rate detecting means for detecting the flow rate of the fluid passage, upstream of the fluid passage, the forward direction while suppressing the reverse flow diffuses to the peripheral flow from the center Therefore, when there is a pulsation, the pulsation is absorbed, and even when there is no pulsation, the flow rate can be accurately measured without causing flow turbulence.
[0027]
(2) Since the pressure fluctuation control valve gives a swirl flow to the fluid, the flow stability can be further enhanced by the swirl flow, and the measurement accuracy is high.
[0028]
(3) Since the pressure fluctuation absorbing valve has vanes and gives a swirling flow, the flow stability is high.
[0029]
(4) A fluid passage, a flow rate detecting means for detecting a flow rate of the fluid passage, and a pressure fluctuation control valve for suppressing the flow in the reverse direction and passing the fluid in the forward direction on the downstream side of the fluid passage. Since it is provided, the flow fluctuation in the pressure fluctuation control valve has little influence on the flow rate measurement accuracy and can be measured with high accuracy.
[0030]
(5) A communication flow path that bypasses the passage of the pressure fluctuation control valve is provided. When the flow rate is small, the valve body is bypassed and the flow fluctuation due to the pressure fluctuation control valve is small, and measurement can be performed with high accuracy.
[0031]
【The invention's effect】
The flow rate measuring device of the present invention absorbs the pulsation when there is pulsation, and can accurately measure the flow rate without causing turbulence even when there is no pulsation. Distribution can be stabilized.
[Brief description of the drawings]
FIG. 1 is a block diagram of a flow rate measuring device according to a first embodiment of the present invention. FIG. 2 is a block diagram of a flow rate measuring means in the same device. (A) Front view showing the pressure fluctuation control valve of the flow rate measuring apparatus according to the third embodiment of the present invention (b) Plan view showing the pressure fluctuation control valve of the flow rate measuring apparatus according to the third embodiment of the present invention FIG. FIG. 6 is a configuration diagram of a pressure fluctuation control valve of a flow rate measuring device according to a fourth embodiment of the invention. FIG. 6 is a configuration diagram of a conventional flow rate measuring device.
5 Fluid passage 6 Flow rate detection means 7 Fluctuating pressure control valve 7b Valve body 16 Valve body 16a Blade 17 Valve seat 17b Communication flow path

Claims (2)

A fluid passage, flow rate detecting means for detecting a flow rate of the fluid passage, and pressure fluctuation control for suppressing a flow in the reverse direction and a flow for diffusing the fluid in the forward direction on the upstream side or the downstream side of the fluid passage. A flow rate measuring device comprising a valve and a blade of the pressure fluctuation control valve.   The flow rate measuring apparatus according to claim 1, further comprising a communication flow path that bypasses the passage of the pressure fluctuation control valve.

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