JP4881066B2 - Flowmeter - Google Patents

Description

  The present invention relates to a flow meter, and more particularly to a flow meter configured to detect that an error has occurred in a flow rate measurement value.

  In a flowmeter that measures the flow rate of fluid, a rotor that rotates according to the flow rate, a mechanical transmission mechanism that transmits the rotation of the rotor, and a mechanical flow indicator that indicates the flow rate according to the number of rotations, Have Therefore, in this type of flowmeter, the rotation of the rotor is transmitted to the flow rate indicator via a mechanical transmission mechanism such as a gear, and the flow rate is visually displayed by the pointer, and the rotational speed reduced by the sensor The flow rate pulse is output in proportion to the flow rate, and the flow rate per unit time is calculated by calculating the flow rate pulse (see, for example, Patent Document 1).

Further, a slit reflector (detected body) is provided on each of the rotors composed of a pair of elliptical gears, and each of the two flow rate pulses obtained by detecting the reflected light from these slit reflectors with an optical sensor. There is also a flowmeter configured to calculate a flow rate and notify an abnormality when the obtained two flow rates are different (for example, see Patent Document 2).
Japanese Patent No. 3128078 Japanese Patent Laid-Open No. 3-84426

  However, in the flow meter configured as described above, when a failure occurs due to damage or wear of the mechanical transmission mechanism, the accurate flow rate is not displayed, and where the transmission mechanism has failed. Since it is not known, there is a problem that it is difficult to determine whether or not the flow rate display by the flow rate instruction unit is accurate.

  In addition, when the abnormality detection means of Patent Document 2 described above is applied to a flow meter as in Patent Document 1 having a mechanical flow rate instruction unit, the rotation of the rotor is detected by a pair of sensors and the signals of both sensors are detected. Therefore, it is only possible to detect an abnormality by the sensor, and it is not possible to detect that a failure has occurred in the mechanical transmission mechanism.

  Therefore, in view of the above circumstances, an object of the present invention is to provide a flow meter that solves the above problems.

  In order to solve the above problems, the present invention has the following means.

The present invention comprises a pair of flow measurement rotors,
A pair of rotating shafts for supporting the pair of flow measuring rotors;
A mechanical flow indicator that is provided on one end of the pair of rotary shafts and indicates the flow rate by transmitting the rotation of the rotary shafts via a reduction gear that reduces the rotational speed of the rotary shafts and a magnetic coupling. When,
A pair of gears provided on the other end side of the pair of rotating shafts, coupled to the pair of rotating shafts and meshing with each other;
A flow meter comprising:
A first detected member attached to at least one of the pair of gears;
A first detector that is provided at a position facing the first detected member and outputs a first flow rate pulse each time the first detected member is detected;
A second detection member provided in the rotating part of the flow rate instruction part;
A second detection unit that is provided at a position facing the second detection member and outputs a second flow rate pulse every time the second detection member is detected;
Determining whether the number of first flow rate pulses output from the first detection unit and the number of second flow rate pulses output from the second detection unit are in a predetermined proportional relationship; An abnormality detection means for detecting the presence or absence of an abnormality by
It is provided with.

  Further, the present invention compares the first flow rate measured using the first flow rate pulse with the second flow rate measured using the second flow rate pulse, and the first flow rate and the first flow rate are compared. The smaller one of the two flow rates is used as the normal flow rate.

  According to the present invention, the number of the first flow rate pulses corresponding to the rotation of the rotating shaft transmitted through the speed reducer and the magnetic coupling for reducing the rotation speed of the rotating shaft, and the rotation on the other end side of the rotating shaft. In order to detect the presence or absence of an abnormality by determining whether or not the number of second flow rate pulses according to the relationship is in a predetermined proportional relationship, whether a flow rate pulse measurement error has occurred due to an abnormality in the speed reducer and magnetic coupling It becomes possible to determine whether or not.

  Further, according to the present invention, when a measurement error occurs because the smaller flow rate of the first flow rate by the first flow rate pulse and the second flow rate by the second flow rate pulse is used as the normal flow rate. However, instead of making measurement impossible, it becomes possible to settle the charge for the flow rate supplied by the smaller flow rate, and it is possible to prevent charging more than the actual supply amount.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

  FIG. 1 is a longitudinal sectional view showing an embodiment of a flow meter according to the present invention. FIG. 2 is a longitudinal sectional view taken along line II-II in FIG. As shown in FIGS. 1 and 2, the flow meter 10 is provided in the middle of a pipe (not shown) for supplying city gas, for example, and measures the flow rate of the gas flowing through the pipe. Consists of.

  The flow meter 10 includes a casing 20, a flow rate instruction unit 30 provided integrally with the casing 20, and a rotation transmission mechanism 40 that transmits rotation from the casing 20 to the flow rate instruction unit 30. The casing 20 has a flow path 20c that communicates the inflow port 20a and the outflow port 20b, and has a measuring chamber 50 in the middle of the flow path 20c. A pair of eyebrows-shaped rotors (flow rate measuring rotors) 60 are assembled in the measuring chamber 50 with a phase difference of 90 degrees, and the pair of rotors 60 is a pair of rotating shafts press-fitted into the center holes, respectively. 70.

  Further, side lids 22 and 24 for closing the measuring chamber 50 are screwed to both side end surfaces of the casing 20. Furthermore, covers 26 and 28 that cover the outer sides of the side lids 22 and 24 are screwed to both end surfaces of the casing 20.

  A seal member 80 is interposed between the covers 26 and 28 and both side end surfaces of the casing 20 so that the inside of the covers 26 and 28 is hermetically sealed. Both ends of the rotating shaft 70 pass through the side lids 22 and 24 and protrude into the covers 26 and 28, respectively.

A pair of rotors 60 are combined via a minute clearance from one another, also rotates while keeping a small clearance against the inner wall of the weighing chamber 50. In addition, since the pair of rotors 60 are provided with a 90-degree offset, rotational force due to fluid pressure is alternately applied. Therefore, a rotation transmission drive gear 72 is fitted and fixed to the end of one end of each rotary shaft 70 (the right end in FIG. 1). The pair of drive gears 72 mesh with each other so that the rotational force generated when the pair of rotors 60 rotates at a rotational speed corresponding to the flow rate is transmitted to the rotary shaft 70 via the drive gear 72. It has become.

  In the flow meter 10 configured as described above, when the gas flows through the flow path 20c of the casing 20, the pair of rotors 60 rotate in the A and B directions as shown in FIG. A space 52 as shown by hatching in FIG. 2 is formed between the rotor 60 and the measuring chamber 50, and a volume of gas (measuring fluid) in the space 52 as the rotor 60 rotates rotates the outlet 20 b. Sent to the side.

  The flow rate instruction unit 30 includes a scale plate 32 and a meter needle 34 to which the rotation of the rotor 60 is transmitted via the rotation transmission mechanism 40. Further, the rotation transmission mechanism 40 is provided with a reduction gear 100 that transmits the rotation of the rotary shaft 70 through the magnetic coupling 90, and the rotation reduced by the reduction gear 100 having a plurality of gears is measured by the meter needle 34 (main In the embodiment, the meter needle 34 is used as a meter, but an integrating counter may be used), and the needle drive mechanism 36 is rotated. Accordingly, the meter needle 34 is rotationally displaced to a position (rotation angle) for instructing a flow rate value with respect to a scale (not shown) formed on the outer peripheral edge of the scale plate 32.

  The magnetic coupling 90 is a so-called magnet coupling, and a main driving side magnet 92 and a driven side magnet 94 to which the rotation of the rotor 60 is transmitted are concentrically arranged, and fluid outflow is prevented between the two magnets. A partition wall 96 is provided. Further, in the reduction gear 100, a plurality of gears are engaged with each other, and the number of teeth of each gear is set so as to have a predetermined reduction ratio.

  In addition, a first rotation detection unit 130 into which a rotation shaft 120 that transmits rotation decelerated by the speed reducer 100 is inserted is provided above the flow rate instruction unit 30. The first rotation detector 130 includes a first detected body 132 provided at the upper end of the rotating shaft 120 and a first magnetic sensor 134 (magnetic sensor) that detects the rotation of the first detected body 132. 134, a reed switch may be used). The first detected body 132 is formed in a disk shape, and a plurality of magnets are embedded at regular intervals in the circumferential direction. Accordingly, the first magnetic sensor 134 outputs a flow rate pulse corresponding to the number of magnets that have passed since the magnet of the first detected body 132 passes when the first detected body 132 rotates. In the present embodiment, a plurality of magnets are embedded in the first object 132 at regular intervals. However, the present invention is not limited to this configuration. For example, only one magnet may be embedded. good. In this case, the magnetic sensor 134 outputs a flow rate pulse corresponding to the rotational speed of the rotary shaft 120.

  A second rotation detection unit 140 is provided on the other end (right end in FIG. 1) side of the pair of rotation shafts 70. The second rotation detector 140 includes a second detected body 142 provided on one of the pair of rotating shafts 70 and a second magnetic sensor 144 that detects the rotation of the second detected body 142. (A reed switch may be used as the magnetic sensor 144). The second rotating body 142 is formed in a disk shape, and a plurality of magnets are embedded at regular intervals in the circumferential direction. The second detected body 142 is provided in the cover 28, and the magnetic sensor 144 is provided on the outer wall of the cover 28. Therefore, the magnetic sensor 144 outputs a flow rate pulse corresponding to the number of magnets that have passed since the magnet of the second detected body 142 passes when the second detected body 142 rotates. In the present embodiment, a plurality of magnets are embedded in the second detected body 142 at regular intervals. However, the present invention is not limited to this configuration. For example, only one magnet may be embedded. good. In this case, the magnetic sensor 144 outputs a flow rate pulse corresponding to the rotational speed of the rotary shaft 70.

  The second flow rate pulse number P2 and the first flow rate pulse number P1 output from the second magnetic sensor 144 both increase or decrease in proportion to the rotation speed of the rotary shaft 70, and the second The flow rate pulse number P2 and the first flow rate pulse number P1 are in a predetermined proportional relationship. That is, if there is no abnormality in the flow meter 10, theoretically, the first flow rate pulse number P1 is obtained by multiplying the second flow rate pulse number P2 by the predetermined coefficient α (P2 · α = P1).

  The first magnetic sensor 134 and the second magnetic sensor 144 are connected to the arithmetic device 150 schematically shown in FIG. 1 via signal lines 152 and 154. This arithmetic device 150 compares the flow rate calculation unit 160 that calculates the flow rate by integrating the flow rate pulses from the magnetic sensors 134 and 144 with the number of flow rate pulses from the magnetic sensors 134 and 144 as will be described later. And an abnormality detection unit 170 for detecting

  Here, the arithmetic processing executed by the abnormality detection unit 170 will be described with reference to the flowchart of FIG. As shown in FIG. 3, the abnormality detection unit 170 checks whether or not the flow rate pulse P1 from the first magnetic sensor 134 is input in S11. In S11, when the flow rate pulse P1 from the first magnetic sensor 134 is not input, the process proceeds to S12, and it is checked whether or not the second flow rate pulse output from the second magnetic sensor 144 is input. In S11, when a flow rate pulse is input from the first magnetic sensor 134, the process proceeds to S13, and 1 is added to the count value P1 of the first flow rate pulse. And it returns to S11 again.

  In S12, when the second flow rate pulse output from the second magnetic sensor 144 is input, the process proceeds to S14, and the numerical value obtained by multiplying the count value P2 of the second flow rate pulse number by the predetermined coefficient α. And whether or not the count value P1 of the first flow rate pulse is equal. In S14, when the value obtained by multiplying the count value P2 of the second flow rate pulse number by the predetermined coefficient α is equal to the count value P1 of the first flow rate pulse, there is no abnormality, so that the process proceeds to S15 and the count value P1 is set. Reset. Subsequently, in S16, measurement mode 1 is set in which the flow rate pulse P1 from the first magnetic sensor 134 is integrated to calculate the flow rate. And it returns to S11 again.

  In S14, when the value obtained by multiplying the count value P2 of the second flow rate pulse number by the predetermined coefficient α is not equal to the count value P1 of the first flow rate pulse, the magnetic coupling 90 or the speed reducer 100 Since there is a high possibility that an abnormality has occurred, the process proceeds to S17, and whether or not the count value P1 of the first flow rate pulse is larger than the value obtained by multiplying the count value P2 of the second flow rate pulse number by the predetermined coefficient α. Check.

  In S17, if the count value P1 of the first flow rate pulse is larger than the value obtained by multiplying the count value P2 of the second flow rate pulse number by the predetermined coefficient α, the process proceeds to S18 and the count value P1 is abnormal. And the P1 abnormality detection signal is output. Then, it progresses to S20 and it is checked whether the reset signal was input. In S20, when the reset signal is input, the process proceeds to S21, and the output of the abnormality detection signal is stopped. In S22, the measurement mode 2 is set so that the flow rate is calculated based on the smaller value among the values obtained by multiplying the count value P1 and the count value P2 calculated in S17 by the predetermined coefficient α.

  When this measurement mode 2 is set, the smaller flow rate of the first flow rate by the first flow rate pulse and the second flow rate by the second flow rate pulse is used as the normal flow rate. Even if it occurs, it is possible not to make the measurement impossible, but to settle the charge for the flow rate supplied by the smaller flow rate, and to prevent charging more than the actual supply amount. And it returns to S11 again.

  In S17, if the count value P1 of the first flow rate pulse is smaller than the value obtained by multiplying the count value P2 of the second flow rate pulse number by the predetermined coefficient α, the process proceeds to S19 and the second magnetic sensor 144 is reached. It is determined that some abnormality has occurred, and a P2 abnormality detection signal is output. And the process of said S20-S22 is performed.

  As described above, in the present invention, the count value P <b> 1 by the first magnetic sensor 134 that detects the rotation through the magnetic coupling 90 or the speed reducer 100 and the count value by the second magnetic sensor 144 that detects the rotation of the rotor 60. When P2 and P2 are not matched, it can be determined that some abnormality has occurred in the magnetic coupling 90 or the speed reducer 100. On the other hand, when the count value P1 by the first magnetic sensor 134 matches the count value P2 by the second magnetic sensor 144, the magnetic coupling 90 or the speed reducer 100 functions normally. Can be determined.

  In addition, although the process of the abnormality detection part 170 was demonstrated in the said description, since the flow volume calculation process which the flow volume calculating part 160 performs is the same as a normal flow volume calculation process, the description is abbreviate | omitted here.

  In the present embodiment, the abnormality detection signal is output when the count value P1 of the first flow rate pulse and the value obtained by multiplying the count value P2 of the second flow rate pulse number by the predetermined coefficient α do not match. However, while this abnormality detection signal is output, an alarm device (not shown) notifies that fact while the abnormality detection signal is being output, or a public line, etc. Of course, it is also possible to report to a maintenance center or the like.

  In the above embodiment, the case where the flowmeter measures a fluid such as a gas has been described as an example. However, the present invention is not limited to this, and the present invention is also applicable to a case where a fluid other than a gas (including a gas and a liquid) is measured. Of course, it can be applied.

  In the above-described embodiment, the positive displacement flowmeter having an eyebrows-shaped rotor has been described as an example. However, the present invention is not limited thereto, and the present invention is also applied to a flowmeter having a rotating body of another shape. Of course you can.

  In the above embodiment, a configuration using a magnetic sensor for rotation detection has been described. However, other sensors (for example, a photosensor such as a photo interrupter) may be used.

It is a longitudinal cross-sectional view which shows one Example of the flowmeter by this invention. It is a longitudinal cross-sectional view which follows the II-II line in FIG. It is a flowchart for demonstrating the arithmetic processing which the abnormality detection part 170 performs.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Flowmeter 20 Casing 30 Flow instruction | indication part 40 Rotation transmission mechanism 50 Measuring chamber 60 Rotor 70 Rotating shaft 90 Magnetic coupling 100 Reduction gear 130 1st rotation detection part 132 1st to-be-detected body 134 1st magnetic sensor 140 Second rotation detection unit 142 Second detection target 144 Second magnetic sensor 150 Calculation device 160 Flow rate calculation unit 170 Abnormality detection unit

Claims (2)

A pair of flow measurement rotors;
A pair of rotating shafts for supporting the pair of flow measuring rotors;
A mechanical flow indicator that is provided on one end of the pair of rotary shafts and indicates the flow rate by transmitting the rotation of the rotary shafts via a reduction gear that reduces the rotational speed of the rotary shafts and a magnetic coupling. When,
A pair of gears provided on the other end side of the pair of rotating shafts, coupled to the pair of rotating shafts and meshing with each other;
A flow meter comprising:
A first detected member attached to at least one of the pair of gears;
A first detector that is provided at a position facing the first detected member and outputs a first flow rate pulse each time the first detected member is detected;
A second detection member provided in the rotating part of the flow rate instruction part;
A second detection unit that is provided at a position facing the second detection member and outputs a second flow rate pulse every time the second detection member is detected;
Determining whether the number of first flow rate pulses output from the first detection unit and the number of second flow rate pulses output from the second detection unit are in a predetermined proportional relationship; An abnormality detection means for detecting the presence or absence of an abnormality by
A flow meter characterized by comprising:   The first flow rate measured using the first flow rate pulse is compared with the second flow rate measured using the second flow rate pulse, and the first flow rate and the second flow rate are compared. The flowmeter according to claim 1, wherein the smaller flow rate is used as the normal flow rate.

Images