JP2003329494A - Flow rate measuring device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To perform accurate measurement when pressure changes or even when the pressure is constant. <P>SOLUTION: This flow rate measuring device has a flow rate detecting means 6 for detecting a flow rate of a fluid passage 5, and a pressure fluctuation control valve 6 for restraining an inverse directional flow, and constituting a flow flowing in from the center and diffusing to the periphery in the forward direction on the upstream side of the fluid passage 5. Thus, a pressure fluctuation is restrained by preventing the inverse directional flow, and an accurate flow rate can be determined without causing turbulence of the flow even in a non-pulsating state. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flow rate measuring device for measuring the flow rate of gas or the like.

[0002]

2. Description of the Related Art A conventional flow rate measuring device of this type will be described with reference to FIG. In the figure, an ultrasonic type flow rate detecting means 2 is provided in a part of the fluid passage 1 to measure the flow rate. When the flow has a periodic fluctuation, the flow rate measurement value varies depending on the measurement timing. For example, in a gas meter that measures the amount of household gas consumed, pressure fluctuations occur when a gas engine is operated nearby. Therefore, the pulsation absorbing device 4 having the valve body 3 for buffering pressure fluctuations
Was provided to reduce the pulsation level.

[0003]

However, the conventional flow rate measuring device has a drawback that the flow turbulence and the deviation of the flow velocity distribution caused by the pulsation absorbing device deteriorate the accuracy of the flow rate measurement.

[0004]

In order to solve the above-mentioned problems, the present invention provides a fluid passage, a flow rate detecting means for detecting the flow rate of the fluid passage, and a reverse flow on the upstream side of the fluid passage. And a pressure fluctuation control valve that forms a flow that flows in from the center and diffuses to the periphery in the forward direction. According to the above-mentioned invention, the flow in the opposite direction is prevented and the pressure fluctuation is suppressed, and the accurate flow rate is obtained without causing the flow turbulence even in the absence of pulsation.

[0005]

BEST MODE FOR CARRYING OUT THE INVENTION According to the present invention, a fluid passage, a flow rate detecting means for detecting a flow rate of the fluid passage, an upstream side of the fluid passage, a flow in a reverse direction are suppressed and a forward direction from a center. It is equipped with a pressure fluctuation control valve that forms a flow that flows in and diffuses to the surroundings.If there is pulsation, it absorbs the pulsation, and even if there is no pulsation, flow turbulence does not occur and the flow rate is accurate. measure.

Further, the pressure fluctuation control valve gives a swirling flow to the fluid, and the swirling flow enhances the stability of the flow.

Further, the pressure fluctuation absorbing valve is provided with a vane, and a swirling flow is given by the vane to stabilize the flow.

Further, 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 a reverse flow and allowing a fluid to pass in a forward direction on the downstream side of the fluid passage. Since it is equipped with and, the influence of flow turbulence in the pressure fluctuation control valve on the flow rate measurement accuracy is small.

Further, the pressure fluctuation control valve is provided with a communication passage for bypassing the passage, and when the flow rate is small, the flow fluctuation is small due to the flow through the communication passage.

[0010]

Embodiments of the present invention will be described below with reference to the drawings.

(Embodiment 1) FIG. 1 is a configuration diagram showing a flow rate measuring apparatus according to Embodiment 1 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 in the passage.
The flow rate detecting means 6 is provided with ultrasonic transmitters / receivers 6a and 6b on the upstream side and the downstream side of the flow, respectively. Is calculated and the details will be described later. A valve seat 7a, a valve body 7b, and a spring 7 are provided upstream 5a of the flow rate detecting means 6.
A pressure fluctuation control valve 7 consisting of c is provided.

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 close the valve seat 7b by urging the spring 7c against the weight of the valve body 7a. When the fluid flows in the forward direction, the valve element 7b is pushed downward against the force of the spring 7c to open the valve. When there is no flow, the valve body 7b is the spring 7
Although the valve seat 7a is closed by c, the valve body 7b is pushed down as shown in the figure by the pressure difference in the forward flow (direction of the arrow) to open the valve. When the flow in the forward direction becomes large, the opening degree of the valve becomes larger and the pressure loss does not increase significantly. When the flow in the opposite direction is generated due to the pressure fluctuation, the valve body 7 receives an upward force and strongly closes the valve seat 7a to stop the flow.

That is, when there is no average flow in the fluid passage or when the flow rate is small on average, the backflow generated by the pressure fluctuation is prevented, and the forward flow is also suppressed because the valve opening is small. The pulsating flow is reduced, the value of the flow rate detecting means 6 does not fluctuate greatly, and the average flow rate can be calculated. Further, when a large flow rate flows in the fluid passage, the differential pressure generated in the valve body 7b becomes large, so the valve body 7b is displaced downward in the figure to increase the valve opening degree, and significantly increase the pressure loss. There is no. At this time, if a pressure fluctuation occurs, the valve opening is large and the effect of suppressing the pressure fluctuation is small, so a flow rate error is generated, but since the average flow rate is large and the error ratio is relatively small, there is no problem.

If the opening of the valve body 7a becomes too large, a stopper (not shown) for restricting the maximum opening can be attached.

If the pressure fluctuation control valve 7 is provided on the upstream side of the flow rate detecting means 6, the pressure fluctuation is suppressed in this portion, so that the influence of pulsation on the flow rate detecting means 6 is further reduced. The directions of the valve body 7b and the spring 7c can be freely selected.

On the other hand, it is conceivable that the flow rate will be changed and the flow rate accuracy will be deteriorated by providing the valve element on the upstream side.
However, the fluid flows in from the valve seat 7a in the center of the flow path,
Since the fluid diffuses and flows in the circumferential direction from the gap between the valve body 7b and the valve seat 7a, the influence on the flow rate detecting hand is extremely small.
Further, at the inlet of the fluid passage 5, 5a flows in with a flow velocity distribution biased by the one connected to the upstream side (for example, a bent pipe), but is diffused when passing through the valve body 7b to detect the flow rate. The means 6 has a flow velocity distribution with no deviation.

FIG. 2 shows the details of the flow rate detecting means using ultrasonic waves. In FIG. 2, the second transceiver 6b that transmits and receives with the first transceiver 6a is arranged in the flow direction. Reference numeral 8 is a flow rate calculating means for processing and calculating a signal based on ultrasonic waves, 9 is a transmission circuit, and the first means is provided by the trigger means 10.
The transmitter / receiver 6a is driven and ultrasonic waves are transmitted toward the second transmitter / receiver 6b, that is, from upstream to downstream. The amplifier circuit 11 amplifies the signal received by the second transceiver 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 repeating means 13 triggers again. The time after the transmission is performed from the means 10 and the above-mentioned transmission / reception is repeated a predetermined number of times is obtained by the time measuring means 14 such as a timer counter.

Next, the switching means 15 switches the transmission / reception of the first transceiver 6a and the second transceiver 6b, and the second transceiver 6
The ultrasonic signal is transmitted from b to the first transceiver 6a, that is, from the downstream side to the upstream side, this transmission is repeated as described above, and the time is counted. Then, the flow rate calculation means 8 obtains the flow rate value from the time difference in consideration of the size of the pipeline and the flow state.

(Embodiment 2) FIG. 3 is a block diagram showing an embodiment of the present invention. In FIG. 3, a valve seat 7a and a valve body 7b are provided downstream of the flow rate detecting means 6 provided in the fluid passage 5. A pressure fluctuation control valve 7 is provided.

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 (direction of the arrow), the valve body 7b floats up and opens the valve due to the pressure difference as shown in the figure. When the flow in the forward direction becomes large, the opening degree of the valve becomes larger and the pressure loss does not increase significantly. When the flow in the opposite direction is generated due to the pressure fluctuation, the valve body 7 receives a downward force and, together with its own weight, strongly closes the valve seat 7a to stop the flow.

Since the pressure fluctuation control valve 7 is located on the downstream side of the flow rate detecting means 6, even if the flow is somewhat disturbed at this portion, it does not adversely affect the flow rate detection.

(Embodiment 3) FIG. 4 shows a valve body 7b. FIG. 4 (a) is a front view and FIG. 4 (b) is a plan view thereof. The valve body 16 operates almost the same as the valve body 7b described above, but the flow is swirled by a plurality of blades such as the blade 16a. This swirling flow makes it possible to stabilize the flow velocity distribution even with respect to a flow having a significantly deviated flow velocity distribution.

(Embodiment 4) FIG. 5 shows the flow path 1 communicating with the valve seat 17.
7a is provided, and when the flow rate is small, this communication flow path 17a
Since the fluid passes through the valve body 18 and the position of the valve body 18 does not change, the flow is extremely stable. Further, if the valve element 18 is spherical, it is more symmetrical with respect to the center and stable against flow. The communication channel 17a may be provided in the valve body 18.

It is preferable that the valve body is lighter in weight so as to improve the responsiveness. Therefore, it may be made of a material having a specific gravity as small as possible or may be made hollow.

[0025]

As is apparent from the above description, the following effects can be obtained by the flow rate measuring device of the present invention.

(1) According to the present invention, the fluid passage, the flow rate detecting means for detecting the flow rate of the fluid passage, the upstream side of the fluid passage, the flow in the reverse direction are suppressed, and the fluid flows in from the center in the forward direction. Since it has a pressure fluctuation control valve that forms a flow that diffuses to the surroundings, it absorbs pulsation when there is pulsation, and even when there is no pulsation, flow turbulence does not occur and the flow rate can be accurately measured. .

(2) Since the pressure fluctuation control valve gives a swirling flow to the fluid, the swirling flow can further enhance the stability of the flow and the measurement accuracy is high.

(3) Since the pressure fluctuation absorbing valve has vanes and gives a swirling flow, the flow stability is high.

(4) A fluid passage, a flow rate detecting means for detecting a flow rate of the fluid passage, and a pressure fluctuation control for suppressing a reverse flow and allowing a fluid to pass in a forward direction on the downstream side of the fluid passage. Since the valve is provided, the flow fluctuation in the pressure fluctuation control valve has little influence on the flow rate measurement accuracy, and high-precision measurement is possible.

(5) A communication passage for bypassing the passage of the pressure fluctuation control valve is provided, and when the flow rate is small, the valve body bypasses the flow, so that the flow fluctuation due to the pressure fluctuation control valve is small and highly accurate. Can be measured.

[Brief description of drawings]

FIG. 1 is a configuration 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 device.

FIG. 3 is a configuration diagram of a flow rate measuring device according to a second embodiment of the present invention.

FIG. 4A is a front view showing a pressure fluctuation control valve of a flow rate measuring device according to a third embodiment of the present invention. FIG. 4B is a plan view showing a pressure fluctuation control valve of a flow rate measuring device according to a third embodiment of the present invention.

FIG. 5 is a configuration diagram of a pressure fluctuation control valve of a flow rate measuring device according to a fourth embodiment of the present invention.

FIG. 6 is a block diagram of a conventional flow rate measuring device.

[Explanation of symbols]

5 fluid passages 6 Flow rate detection means 7 Fluctuating pressure control valve 7b Disc 16 valve body 16a feather 17 seat 17b Communication channel

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Claims (5)

[Claims] 1. A fluid passage, a flow rate detecting means for detecting a flow rate of the fluid passage, and a pressure which, in the upstream side of the fluid passage, suppresses a flow in a reverse direction and gives a flow for diffusing a fluid in a forward direction. A flow measurement device equipped with a fluctuation control valve. 2. The flow rate measuring device according to claim 1, wherein a swirl flow is applied to the fluid by a pressure fluctuation control valve. 3. The pressure fluctuation control valve is provided with vanes.
The flow control device described. 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 a reverse flow and allowing a fluid to pass in a forward direction on the downstream side of the fluid passage. A flow rate measuring device equipped with. 5. The flow rate measuring device according to claim 1, further comprising a communication flow passage that bypasses a passage of the pressure fluctuation control valve.