JPS6173024A - Piston prober - Google Patents

Abstract

PURPOSE:To measure the instrumental error of a positive displacement flowme ter which varies in discharge quantity periodically with high precision by detecting the position of a piston which moves in a prober. CONSTITUTION:When a pump 8 is put in operation to start supplying fluid, a flowmeter M to be detected outputs a pulse to a controller 7 at every time its output shaft rotates by a specific angle. A fluid supplied from an auxiliary pipe 4 through the flowmeter to be detected, on the other hand, moves the piston 3 and a scale member 1 to left. A position sensor 5 reads a magnetic scale 1a and outputs a signal to the controller 7. When the flow rate signal from the flowmeter M to be detected is an integral multiple of one period which is set previously and the piston 3 moves almost to an end pat of a cylinder 2, the controller 7 stops the counting operation to close three-way valves V1 and V2; and a flow rate is calculated from the counted at the same time and a flow rate is calculated from a signal counted value from the position sensor 5, so that the instrumental error is calculated from both flow rate values and displayed on a display meter 9.

Description

[Detailed description of the invention] (Technical part! 7) The uninvented object is a piston suitable for instrumental error measurement of a meter such as a piston-type capacity flow meter in which a rotary machine with a discharge flow rate output shaft periodically changes. Regarding provers.

(Prior art) The piston blue used for calibration of flowmeters, etc., uses a sensor that detects the start and end of the piston stroke to count pulses from the flowmeter to the 7th U, while the valve sensor While controlling the open/close switching ffj of the control valve installed between the laminar flow meter and the piston prover, the piston is stably reciprocated within the set stroke, and the internal volume when making one reciprocation is as follows. It is configured to calibrate the instrumental error of the flowmeter using as a reference quantity.

On the other hand, the movement of the piston, which reciprocates while maintaining airtightness with the cylinder, is converted into rotational movement by a crank mechanism.
A piston-type positive displacement flowmeter that measures the flow rate from the rotation amount has a periodic rotation phase of the flow output shaft and a discharge amount, for example, 4
With a piston-type flowmeter, the flow rate fluctuates every time the output shaft rotates 90 degrees.

Even when measuring the same volume of fluid, there is a problem in that the indicated value of the flowmeter varies depending on the rotational phase, resulting in errors in instrumental measurement.

(Objective) In view of these problems, the present invention aims to provide a piston prover that can measure with high precision the instrumental error of a positive displacement flowmeter, such as a piston type positive displacement flowmeter, in which periodic changes occur in the discharge amount. purpose.

(Structure) In other words, the feature of the present invention is that by detecting the position of the piston moving inside the prover, it is possible to accurately measure the internal volume of the blue no matter where the piston is located. By doing so, it is possible to detect the reference volume at the time when the test volume flow meter measures an integral multiple of the periodic fluctuation.

Therefore, details of the present invention will be explained below based on illustrated embodiments.

FIG. 1 is a sectional view showing an embodiment of a piston prover according to the present invention, and reference numeral 1 in the figure is a scale member attached to one end of a piston 3 that reciprocates within a cylinder 2.
It has a length that covers the stroke length of the piston 3, has a magnetic scale 1a in the axial direction of the cylinder 2, and is slidably supported by a bearing 4a provided at the cylinder side end of an auxiliary pipe 4, which will be described later. has been done. Reference numeral 4 denotes an auxiliary tube having a length that allows for the protrusion of the scale member l, and a position sensor 5 consisting of a magnetic detector is disposed at the end on the cylinder side so as to face the scale 1a. As shown in FIG. 2, a conduit 4a communicating with the flowmeter to be tested and the discharge side flow path is connected via two three-way valves v1 and v2. Reference numeral 6 denotes an auxiliary pipe attached to the other end of the cylinder, to which a conduit 6a communicating with the flowmeter to be tested and the discharge side flow path is connected via two three-way valves V, , V2.

FIG. 2 shows an example of an instrumental difference measuring device using the above-mentioned piston prover, and the reference numeral 7 in the figure is a control device that controls the operation of the entire device, and the start switch S
The three-way valve V! is activated by the activation signal from W! , V2 to form a flow path, pump 8 to supply fluid to the piston prover via the flow meter M to be tested, and at the same time receiving a signal from a position sensor provided on the piston prover. It is configured to measure the flow rate flowing into the prover, and to count pulse signals from the flowmeter to be tested and display them on a display meter.

In this embodiment, the flowmeter M to be tested is connected to the flow path via a flange, the pulse generator MP of the flowmeter M to be tested is connected to the control device 7, and one of the flowmeters M to be tested is connected to the control device. Set the flow rate for the period, that is, the number of pulses.

When the start switch Sw is turned on after completing these preparations, a signal is output from the control device 7 and the pump 8 is turned on.
- Flowmeter to be tested M - Stop valve v4 - Three-way valve v1 - A flow path leading to auxiliary pipe 4 is formed, and at the same time pump 8 is operated to start supplying fluid. Thereby, the flow meter M to be tested measures the flow rate of the fluid supplied from the pump and outputs a pulse to the control device 7 every time the output shaft rotates by a certain angle.

On the other hand, the fluid supplied from the auxiliary pipe 4 via the flow meter M to be tested moves the piston 3 and the scale member l attached thereto to the left in the figure. The position sensor 5 reads the magnetic scale 1a and outputs a signal to the control device 7. The control device 7 starts counting signals from the pulse oscillator MP and the position sensor 5 of the flowmeter M to be tested from the point when the scale member l has moved a little. In this way, counting is stopped when the piston 3 moves close to the end of the cylinder 2 at an integer multiple of one period set by the flow j-fold signal 1i11 from the flowmeter M to be tested, and the V ,, close V2, simultaneously calculate the flow rate based on the flow rate pulse count value from the flow meter M to be tested, calculate the flow rate based on the signal count value from the position sensor 5,
The instrumental error is determined from both flow rate values, and these values are displayed on the display meter 9.

FIG. 3 shows a second embodiment of the present invention,
Reference numeral 11.11' in the figure is a scale member that slides in contact with the piston 13 reciprocating within the cylinder 12, and has magnetic scales 11a, 11a' on the surface in the axial direction of the cylinder.
is formed, and the cylinder 1 of the auxiliary pipe 14, 14', which will be described later.
It is slidably supported by bearings L4a and 14a' provided at the two side ends. 14.14° is an auxiliary pipe that allows for the protrusion of the scale member 11.11', and is designed to protrude into the cylinder via a compression spring 15.15° between it and the rear end of the scale member 11.11'. The scale member is accommodated in a biased state, and a position sensor 16 consisting of a magnetic sensor is installed at the end on the cylinder side, facing the magnetic scale.
16' respectively, and two three-way valves v1. Conduit pipes 14b and 14b° communicating with the flowmeter to be tested and the discharge side flow path via V2 are fixedly installed. In addition, sieve numbers 11b and 11b' in FIG. 5 respectively indicate protrusions that prevent the scale member from coming off.

Figure 4 shows the instrumental error J using the piston prover mentioned above.
This figure shows an example of a fixed device, and the reference numeral 17 in the figure
is a control device that supervises the operation of the entire device, and in response to a start signal from the start switch Sw, operates the three-way valves V, V2 to form a flow path, operates the pump 18, and flows through the flowmeter M to be tested. supply fluid to the piston prover, and at the same time receive the signal from the position sensor 16° 16° to determine the volume of fluid flowing into the blue /, and count the pulse signal from the flow meter M to be tested. It is configured to display on the display meter 19.

In this embodiment, the flowmeter to be tested M is connected to the flow path via a flange, the pulse generator MP of the flowmeter to be tested is connected to the display 19, and the flowmeter to be tested MN01 is connected to the control device 7. Set the flow rate for the period, that is, the number of repulses.

When the start switch Sv is turned on after completing such preparations, a signal is output from the control device 17 to connect the pump 18 - the flowmeter to be tested M - the city valve v4 - the three-way valve v the knee auxiliary pipe 1.
4 is formed, and at the same time, the pump 18 is driven to start supplying the fluid.

As a result, the test object Pi, 61: Meter M measures the flow rate of the fluid flowing through the pipe, and outputs a pulse to the control device 17 every time the output shaft rotates by a certain angle.

In this way, if the fluid supply is continued, the piston 1
3 begins to move inside the cylinder toward the left in the figure. From the point when the scale member 11 moves a little, the control device 17 starts the pulse transmitter MP of the flowmeter M to be tested and the position sensor 1.
Start counting signals from 6. The piston 13 starts away from the scale member 11 to the left. When the piston 13 comes into contact with the left scale member 11' in this manner, the scale member 11' is moved to the left by the piston 13 against the compression spring 15'. The position sensor 16' is
A signal from the scale 11a' of the scale member 11' (7) is output to the control device 17, and the control device 17 counts this signal. In this way, counting is stopped when the flow rate signal from the flow meter M to be tested becomes an integral multiple of one period set in advance.

Close the three-way valves V, V2, and at the same time calculate the flow rate by calculating the flow rate from the flow pulse count value from the flow meter M to be tested and the movement amount of the piston 13 from the signal count value from the position sensor 16.16°, The instrumental error is determined from the values of both flow types, and these values are displayed on the display meter 19.

If it is not possible to obtain a volume suitable for verification by moving the piston 13 within the loaf, immediately after the end of one stroke, switch the three-way valves V, , V2, and move the piston 13 into contact with the scale member 11 on the right side. The piston 13 may be moved in multiple directions to a position where a just instruction can be obtained within the contact range.

In the embodiment described above, the amount of movement of the piston is detected using a magnetic scale. The same effect can be achieved by reading .

(Effects) As described above, according to the present invention, the scale member provided with a scale is made to follow the piston to detect the amount of movement of the piston, so the position of the piston within the cylinder can be detected and It is possible to form a prover volume of It is possible to measure by

[Brief explanation of drawings]

FIG. 1 is a sectional view of an apparatus showing one embodiment of the present invention, and FIG.
The figure is a block diagram showing an example of an instrumental error measuring device using the above device, FIG. 3 is a sectional view of the device showing another embodiment of the present invention, and FIG. 4 is an instrumental error measuring device using the same device. FIG. 1 is a configuration diagram showing an example of a measuring device.

Claims (1)

[Claims] A cylinder having a liquid supply port on at least one end, a piston fitted in the cylinder so as to be able to reciprocate, a scale member that follows the movement of the piston, and a position detector that detects the amount of movement of the scale member. A piston prover consisting of means.