Low-flow-velocity compressed air metering device

Abstract

The utility model relates to the technical field of gas flow measurement, in particular to a low-flow-velocity compressed air metering device, which comprises an integrating instrument, and a pressure sensor, a temperature sensor, a vortex shedding flowmeter and a thermal mass flowmeter which are sequentially arranged along the flow direction of gas in a compressed air pipeline, the pressure sensor and the temperature sensor are respectively in signal connection with the integrating instrument, and the signal output end of the vortex shedding flowmeter and the signal output end of the thermal mass flowmeter are respectively connected with the integrating instrument through the detection channel change-over switch. Compared with the prior art, when low flow velocity is measured, a flow detection channel can be switched to the thermal flow meter through the channel change-over switch, and the purpose of low flow velocity measurement is achieved.

Description

A low-flow-rate compressed air metering device Technical Field

[0001] This utility model relates to the field of gas flow measurement technology, and in particular to a metering device for low-velocity compressed air. Background Technology

[0002] Compressed air flow rate is a crucial parameter describing the performance of air compressors and an important measurement parameter in industrial processes. With the widespread application of air compressors, accurate measurement of their flow rate is essential for product upgrades, industrial production process control and monitoring, and energy conservation and cost reduction. Compressed air flow rate refers to the ratio of the amount of compressed air flowing through a specific cross-section in a short period of time to the passage time.

[0003] A compressed air metering device consists of a vortex flow meter, a pressure sensor, a temperature sensor, and an integrator. Under certain pressure and temperature, the flow rate of compressed air is constant.

[0004] The current device can accurately measure the amount of compressed air used under normal conditions. However, during low production hours at night, the amount of compressed air used is small, resulting in a slow flow rate, and the existing flow meter cannot measure the flow rate of the compressed air. Summary of the Invention

[0005] The purpose of this invention is to overcome the shortcomings of the prior art, which is that the flow rate of compressed air cannot be measured when the amount of compressed air used is small, and to provide a metering device for low-flow-rate compressed air.

[0006] The objective of this utility model can be achieved through the following technical solutions:

[0007] A low-flow-rate compressed air metering device includes an integrator and a vortex flow meter installed on a compressed air pipeline. The metering device also includes a thermal mass flow meter installed on the compressed air pipeline. The signal output terminals of the vortex flow meter and the thermal mass flow meter are respectively connected to the integrator through a detection channel switching switch.

[0008] As a preferred technical solution, the metering device further includes a pressure sensor and a temperature sensor installed on the compressed air pipeline, and the pressure sensor and the temperature sensor are respectively connected to the integrator signal.

[0009] As a preferred technical solution, the thermal mass flow meter, vortex flow meter, temperature sensor and pressure sensor are sequentially arranged along the gas flow direction in the compressed air pipeline.

[0010] As a preferred technical solution, the vortex flow meter is model 72F2F-SD0AAPAAA4BW.

[0011] As a preferred technical solution, the thermal mass flow meter is model SUTO S401.

[0012] As a preferred technical solution, the detection channel switching switch includes a double-pole single-control switch. The double-pole single-control switch includes two controlled switches and a switching unit connected to the controlled ends of the two controlled switches. One side of the two controlled switches is connected to a vortex flow meter and a thermal mass flow meter, respectively, and the other side is connected to an integrator. The switching states of the two controlled switches are opposite.

[0013] As a preferred technical solution, the switching unit is a switching lever, which has two position states.

[0014] As a preferred technical solution, when the switching lever is in the first position, the switching lever is connected to the control terminal of the first controlled switch in the double-pole single-control switch, and the first controlled switch is turned on; the second controlled switch is turned off.

[0015] When the switching lever is in the second position, the switching lever is connected to the control terminal of the second controlled switch in the double-pole single-control switch, and the second controlled switch is turned on; the first controlled switch is turned off.

[0016] As a preferred technical solution, the switching unit is a hysteresis comparator.

[0017] As a preferred technical solution, the input terminal of the hysteresis comparator is connected to the output terminal of the vortex flow meter, one output terminal of the hysteresis comparator is connected to the controlled terminal of the corresponding controlled switch of the vortex flow meter, and the other output terminal of the hysteresis comparator is connected to the controlled terminal of the corresponding controlled switch of the thermal mass flow meter after passing through an inverter.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] 1) This utility model installs a thermal mass flow meter at the front end of a vortex flow meter. When measuring low flow rates, the channel switching switch is switched to the thermal flow meter channel to achieve the purpose of low flow rate measurement.

[0020] 2) This invention also employs a hysteresis comparator to achieve automatic switching between the signal channels of the thermal mass flow meter and the vortex flow meter. When the flow velocity is low and the output signal of the vortex flow meter is below the switching threshold, it automatically switches to the signal path of the thermal mass flow meter, improving the real-time switching performance. Attached Figure Description

[0021] Figure 1 is a schematic diagram of the structure of a compressed air flow metering device according to this utility model;

[0022] Figure 2 is a schematic diagram of a channel switching switch in a specific embodiment of this utility model;

[0023] Figure 3 is a schematic diagram of the channel switching switch in another specific embodiment of this utility model;

[0024] The attached diagram shows the following labels: 1. Pressure sensor, 2. Temperature sensor, 3. Vortex flow meter, 4. Thermal mass flow meter, 5. Channel switching switch, 51. First controlled switch, 52. Second controlled switch, 53. Switching lever, 54. Hysteresis comparator, 6. Integrator. Detailed Implementation

[0025] The present invention will now be described in detail with reference to the accompanying drawings and specific embodiments. This embodiment is based on the technical solution of the present invention and provides detailed implementation methods and specific operating procedures; however, the scope of protection of the present invention is not limited to the following embodiments.

[0026] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0027] The following detailed description of some embodiments of the present invention is provided in conjunction with the accompanying drawings. Unless otherwise specified, the following embodiments and features can be combined with each other.

[0028] Example 1

[0029] This invention proposes a device for measuring low-velocity compressed air, as shown in Figure 1. The device includes a thermal mass flow meter 4, a vortex flow meter 3, a temperature sensor 2, and a pressure sensor 1 arranged sequentially along the flow direction of the medium; a channel switching switch 5 and an integrator 6, which are respectively signal-connected to the thermal mass flow meter 4 and the vortex flow meter 3. The device can accurately measure compressed air volume when the usage is small.

[0030] Specifically, in this embodiment, the vortex flow meter 3 is model E+H 72F2F-SD0AAPAAA4BW; the thermal mass flow meter 4 is model SUTO S401.

[0031] As shown in Figure 2, the detection channel switching switch 5 is a double-pole single-control switch, which includes two controlled switches and a switching lever. One side of each controlled switch is connected to the vortex flow meter 3 and the thermal mass flow meter 4, respectively, and the other side is connected to the integrator 6. The switching lever 53 has two position states, while the two controlled switches have opposite on / off states. When the switching lever 53 is in the first position, it connects to the control terminal of the first controlled switch 51 in the double-pole single-control switch, and the first controlled switch 51 is turned on; the second controlled switch 52 is closed. When the switching lever 53 is in the second position, it connects to the control terminal of the second controlled switch 52 in the double-pole single-control switch, and the second controlled switch 52 is turned on; the first controlled switch 51 is closed. This achieves channel control for the vortex flow meter 3 and the thermal mass flow meter 4.

[0032] The working principle of this utility model is based on the principle that the thermal mass flow meter 4 can measure low flow rate. It is installed in front of the vortex flow meter 3. During low production at night, the channel switching switch 5 can be manually switched to the thermal flow meter 4 to achieve the purpose of low flow rate measurement.

[0033] Example 2

[0034] In another specific embodiment of this utility model, the compressed air metering device da in this embodiment is the same as that in Embodiment 1, both including a thermal mass flow meter 4, a vortex flow meter 3, a temperature sensor 2, a pressure sensor 1, and an integrator 6 arranged sequentially along the medium flow direction. The difference from Embodiment 1 is that in this embodiment, the controlled terminals of the two controlled switches in the channel switching switch 5 are controlled and connected through a hysteresis comparator 54. The input terminal of the hysteresis comparator 54 is connected to receive the voltage signal output by the vortex flow meter 3, and one output terminal of the hysteresis comparator 54 is connected to the controlled terminal of the first controlled switch 51 corresponding to the vortex flow meter 3, and the other output terminal is connected to the controlled terminal of the second controlled switch 52 corresponding to the thermal mass flow meter 4 after passing through an inverter.

[0035] When the input voltage of the vortex flowmeter 3 is higher than the positive threshold voltage of the hysteresis comparator 54, the output of the hysteresis comparator 54 is high. At this time, the first controlled switch 51 is turned on and the second controlled switch 52 is turned off. The integrator 6 receives the detection and sensing data from the vortex flowmeter 3. When the input voltage of the vortex flowmeter 3 is lower than the negative threshold voltage, the output of the hysteresis comparator 54 is low. At this time, the first controlled switch 51 is turned off and the second controlled switch 52 is turned on. The integrator 6 receives the detection and sensing data from the thermal mass flowmeter 4. When the input is between the positive and negative threshold voltages, the output does not change. That is to say, the threshold voltages corresponding to the output flipping from a high level to a low level or from a low level to a high level are different.

[0036] In this embodiment, a hysteresis comparator 54 is used to achieve automatic switching between the thermal mass flow meter 4 and the vortex flow meter 3 channels. When the flow rate is low and the output signal of the vortex flow meter 3 is below the switching threshold, the system automatically switches to the signal path of the thermal mass flow meter 4, improving the real-time performance of the switching.

[0037] The preferred embodiments of this utility model have been described in detail above. It should be understood that those skilled in the art can make numerous modifications and variations based on the concept of this utility model without creative effort. Therefore, all technical solutions that can be obtained by those skilled in the art based on the concept of this utility model through logical analysis, reasoning, or limited experimentation on the basis of existing technology should be within the scope of protection defined by the claims.

Claims

1. A low-velocity compressed air metering device, comprising an integrator (6) and a vortex flow meter (3) disposed on a compressed air pipeline, characterized in that, The metering device also includes a thermal mass flow meter (4), which is installed on the compressed air pipeline; the signal output terminals of the vortex flow meter (3) and the thermal mass flow meter (4) are respectively connected to the totalizer (6) through a detection channel switching switch (5).

2. The low-flow-rate compressed air metering device according to claim 1, characterized in that, The metering device also includes a pressure sensor (1) and a temperature sensor (2) installed on the compressed air pipeline, and the pressure sensor (1) and the temperature sensor (2) are respectively connected to the integrator (6) for signal transmission.

3. The low-flow-rate compressed air metering device according to claim 2, characterized in that, The thermal mass flow meter (4), vortex flow meter (3), temperature sensor (2) and pressure sensor (1) are sequentially arranged along the gas flow direction in the compressed air pipeline.

4. The low-flow-rate compressed air metering device according to claim 1, characterized in that, The vortex flow meter (3) is model 72F2F-SD0AAPAAA4BW.

5. A low-flow-rate compressed air metering device according to claim 1, characterized in that, The thermal mass flow meter (4) is model SUTO S401.

6. The low-flow-rate compressed air metering device according to claim 1, characterized in that, The detection channel switching switch (5) includes a double-pole single-control switch. The double-pole single-control switch includes two controlled switches and a switching unit connected to the controlled ends of the two controlled switches. One side of the two controlled switches is connected to a vortex flow meter (3) and a thermal mass flow meter (4), respectively, and the other side is connected to an integrator (6). The switching states of the two controlled switches are opposite.

7. A low-flow-rate compressed air metering device according to claim 6, characterized in that, The switching unit is a switching lever (53), which has two position states.

8. A low-flow-rate compressed air metering device according to claim 7, characterized in that, When the switching lever (53) is in the first position, the switching lever (53) is connected to the control terminal of the first controlled switch (51) in the double-pole single-control switch, and the first controlled switch (51) is turned on; the second controlled switch (52) is turned off. When the switching lever (53) is in the second position, the switching lever (53) is connected to the control terminal of the second controlled switch (52) in the double-pole single-control switch, and the second controlled switch (52) is turned on; the first controlled switch (51) is turned off.

9. A low-flow-rate compressed air metering device according to claim 6, characterized in that, The switching unit is a hysteresis comparator (54).

10. A low-flow-rate compressed air metering device according to claim 9, characterized in that, The input of the hysteresis comparator (54) is connected to the output of the vortex flow meter (3). One output of the hysteresis comparator (54) is connected to the controlled terminal of the corresponding controlled switch of the vortex flow meter (3). The other output of the hysteresis comparator (54) is connected to the controlled terminal of the corresponding controlled switch of the thermal mass flow meter (4) after passing through an inverter.

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