Mass flow meter and mass flow control device

Abstract

To provide a mass flowmeter capable of reducing the probability that a sensor is damaged by high-pressure fluid.SOLUTION: A mass flow meter 1 includes a conduit body 10 and a sensor 12. The conduit body has a main flow passage 14, a first sensor branch passage 16, a second sensor branch passage 18, and a housing chamber 20, both ends of the first and second sensor branch passages being connected respectively to the main flow passage and the housing chamber. The sensor has an inlet gas nozzle 36 and an outlet gas nozzle 38, and is disposed in the housing chamber. The inlet gas nozzle is connected to the first sensor branch passage and the outlet gas nozzle is connected to the second sensor branch passage so that a part of the fluid flowing through the main flow passage enters the sensor via the first sensor branch passage and returns to the main flow passage via the second sensor branch passage to enable measurement of a fluid flow rate. The conduit body is further provided with a pressure chamber 40 and an airway 42.SELECTED DRAWING: Figure 4

Description

Technical Field

[0001] The present invention relates to a technology for detecting and controlling the flow rate of fluids such as liquid and gas, and more specifically, to a mass flow meter capable of reducing the probability of a sensor being damaged by pressure, and a mass flow controller including the mass flow meter.

Background Art

[0002] A Mass Flow Controller (MFC) is a device for measuring and controlling fluid flow rate in consideration of temperature and pressure, and in recent years, it has been universally applied to the measurement and control of the flow rate of compressible fluids such as gas and liquid. Generally, the main components of a mass flow controller include a Mass Flow Meter (MFM), a control valve and a controller. A mass flow meter has a pipe line and a sensor. The pipe line functions to perform filtration, stabilize flow, and connect the sensor to the control valve, etc., the sensor is for monitoring the flow rate of fluid passing through the pipe line and transmitting a flow rate signal to the controller, and the controller adjusts the flow rate of fluid flowing out from the pipe line by controlling the control valve in accordance with the flow rate signal.

[0003] The most important component of the mass flow controller is obviously the mass flow meter. Currently, two types of mass flow meters commonly found on the market are Thermal Mass Flow Meters and Coriolis Mass Flow Meters. A thermal mass flow meter performs measurement by utilizing the thermal diffusion effect of gas, while a Coriolis mass flow meter performs measurement based on the Coriolis principle.

[0004] In practice, since the pipe line and the sensor are manufactured from different materials (usually, the pipe line is made of metal while the sensor is made of plastic), it has been found that the sensor is often damaged by high-pressure fluid in the pipe line body or causes leakage, so that the sensor cannot accurately detect the flow rate of the fluid.

Summary of the Invention

[0005] The object of the present invention is to provide a mass flow meter and a mass flow controller for a mass flow meter that can reduce the probability of the sensor being damaged by a high-pressure fluid.

[0006] To achieve the above-mentioned objectives and effects, the present invention provides a mass flow meter comprising a pipeline body and a sensor. The pipeline body comprises a main channel, a first sensor branch channel, a second sensor branch channel, and a housing chamber. Both ends of the first and second sensor branch channels are connected to the main channel and the housing chamber, respectively, and a filter is provided in the main channel. The sensor has an inlet gas nozzle and an outlet gas nozzle and is located inside a containment chamber. The inlet gas nozzle is connected to a first sensor branch channel, and the outlet gas nozzle is connected to a second sensor branch channel. The fluid flow rate is measured by having a portion of the fluid that has passed through the main channel enter the sensor via the first sensor branch channel, and then return to the main channel via the second sensor branch channel. The main pipeline body is further equipped with a pressure chamber and an airway. The pressure chamber is connected to the containment chamber, and the airway is connected to both the containment chamber and the main flow path. By allowing some of the fluid that has passed through the main flow path to enter the pressure chamber through the airway, the pressure inside and outside the sensor is equalized. The space between the inlet gas nozzle and the side wall of the first sensor tributary, which is created because the diameter of the first sensor tributary is larger than that of the sensor's inlet gas nozzle, forms an airway.

[0007] The present invention provides a mass flow controller that includes a pipeline body, a sensor, and a control valve. The pipeline body comprises a main channel, a first sensor branch channel, a second sensor branch channel, a housing chamber, a main channel after the valve, a first valve branch channel, and a second valve branch channel. Both ends of the first and second sensor branch channels are connected to the main channel and the housing chamber, respectively. One end of the first valve branch channel is connected to the main channel, and one end of the second valve branch channel is connected to the main channel after the valve. A filter is provided in the main channel. The sensor is located in a containment chamber that has an inlet gas nozzle and an outlet gas nozzle. The inlet gas nozzle is connected to a first sensor branch channel, and the outlet gas nozzle is connected to a second sensor branch channel. The fluid flow rate is detected by having a portion of the fluid that has passed through the main channel enter the sensor via the first sensor branch channel, and then return to the main channel via the second sensor branch channel. The control valve has a valve inlet and a valve outlet and is installed in the main pipeline. The valve inlet is connected to a first valve branch passage, and the valve outlet is connected to a second valve branch passage. This causes the fluid in the main passage to enter the control valve via the first valve branch passage, then enter the post-valve main passage via the second valve branch passage. The control valve adjusts the flow rate of the fluid flowing out from the valve outlet according to the flow rate detected by the sensor. The main conduit is further equipped with a pressure chamber and an airway. The pressure chamber is connected to the containment chamber, and the airway is connected to both the pressure chamber and the main flow path. By allowing some of the fluid that has passed through the main flow path to enter the pressure chamber via the airway, the pressure inside and outside the sensor is equalized. The space between the inlet gas nozzle and the side wall of the first sensor tributary, which is created because the diameter of the first sensor tributary is larger than that of the sensor's inlet gas nozzle, forms an airway. [Brief explanation of the drawing]

[0008] [Figure 1] This is a perspective view of a first preferred embodiment of the present invention, showing the external appearance of a mass flow meter. [Figure 2] This is an exploded cross-sectional view of a first preferred embodiment of the present invention. [Figure 3] This is a cross-sectional view of a combination of a first preferred embodiment of the present invention. [Figure 4] This is a magnified view of a portion of Figure 3. [Figure 5] This is a cross-sectional view of a second preferred embodiment of the present invention, showing a mass flow controller having a mass flow meter. [Modes for carrying out the invention]

[0009] As shown in Figures 1 to 4, the mass flow meter 1 disclosed in the first preferred embodiment of the present invention includes a pipeline body 10 and a sensor 12.

[0010] The main pipe body 10 is made of metal and is equipped with a main channel 14, a first sensor branch channel 16, a second sensor branch channel 18, and a containment chamber 20. The main channel 14 has an inlet 22 at one end of the main pipe body 10 and an outlet 24 at the other end. Both ends of the first sensor branch channel 16 and the second sensor branch channel 18 are connected to the main channel 14 and the containment chamber 20, respectively, and the first sensor branch channel 16 is closer to the inlet 22 than the second sensor branch channel 18. The first joint 26 is connected to the inlet 22 to introduce fluid into the main channel 14. The second joint 28 is connected to the outlet 24 to drain the fluid from the main channel 14. A filter 30 for filtering the fluid is placed inside the main channel 14. An airtight ring 32 is provided above the filter 30, and is in contact with the wall surface of the main flow path 14, positioned between the first sensor branch flow path 16 and the second sensor branch flow path 18, so that some of the fluid enters the first sensor branch flow path 16 from outside the filter 30.

[0011] One side of the containment chamber 20 is open to the outer surface of the conduit body 10. After the sensor 12 is placed inside the containment chamber 20, the containment chamber 20 is closed by a closure 34 fixed to the conduit body 10. The sensor 12 has an inlet gas nozzle 36 connected to the first sensor branch channel 16 and an outlet gas nozzle 38 connected to the second sensor branch channel 18.

[0012] With the above combination, most of the fluid entering the main channel 14 from the first joint 26 passes through the filter 30, while some of the fluid enters the sensor 12 from outside the filter 30 via the first sensor branch channel 16, and then returns to the main channel 14 via the second sensor branch channel 18. In this way, the sensor 12 can detect the fluid flow rate, pressure, temperature, humidity, etc., and emit detection signals accordingly.

[0013] The main feature of this invention is the installation of a pressure chamber 40 and an airway 42 in the pipeline body 10. The pressure chamber 40 is connected to the containment chamber 20, and both ends of the airway 42 are connected to the pressure chamber 40 and the main flow path 14, respectively, so that a portion of the fluid that has passed through the main flow path 14 enters the pressure chamber 40 via the airway 42. This makes the pressure experienced inside and outside the sensor 12 nearly the same, reducing the probability that the sensor 12 will be damaged by the high-pressure fluid that enters it.

[0014] As shown in Figure 4, in the first preferred embodiment, the volume of the containment chamber 20 is larger than that of the sensor 12. Therefore, after the sensor 12 is placed in the containment chamber 20, a space is created between the sensor 12 and the side wall of the containment chamber 20, and this space becomes the pressure chamber 40. In other words, the pressure chamber 40 is part of the containment chamber 20, and part of it is space not occupied by the sensor 12. The diameter of each of the first sensor branch passages 16 is larger than that of the inlet gas nozzle 36 of the sensor 12, creating a space between the inlet gas nozzle 36 and the side wall of the first sensor branch passage 16, and this space becomes the airway 42. Most of the fluid that passes through the first sensor branch passages 16 enters the sensor 12 from the inlet gas nozzle 36, and some enters the pressure chamber 40 from the airway 42, thus maintaining the pressure inside and outside the sensor 12 at all times. In practical applications, the aforementioned effect can be achieved by installing an O-ring 44 only on the outlet gas nozzle 38 to create an airtight seal between the pressure chamber 40 and the second sensor branch passage 18, without installing an O-ring on the inlet gas nozzle 36.

[0015] As shown in Figure 5, a second preferred embodiment of the present invention provides a mass flow controller 2 that includes the mass flow meter 1 disclosed in the first preferred embodiment and a control valve 46.

[0016] As described above, the mass flow meter 1 includes a pipeline body 10 and a sensor 12. The pipeline body 10 has a main flow path 14, a housing chamber 20, a first sensor branch flow path 16 and a second sensor branch flow path 18, a pressure chamber 40 and an airway 42. The structure of the above components is the same as described above and will not be explained further. The differences include the following: The pipeline body 10 is further provided with a post-valve main flow path 48, a first valve branch flow path 50 and a second valve branch flow path 52. There is a partition wall 54 between the main flow path 14 and the post-valve main flow path 48 to prevent them from communicating with each other. The first valve branch flow path 50 is located on one side of the partition wall 54 and one end is connected to the main flow path 14. The second valve branch flow path 52 is located on the other side of the partition wall 54 and one end is connected to the post-valve main flow path 48. The second joint 28 has been modified to be connected to one end of the post-valve main flow path 48. The control valve 46 has a valve inlet 56 and a valve outlet 58. The control valve 46 is installed in the pipeline body 10, with the valve inlet 56 connected to a first valve branch passage 50 and the valve outlet 58 connected to a second valve branch passage 52.

[0017] With the above structure, the fluid that enters the main flow path 14 from the first joint 26 first passes through the filter 30, then enters the control valve 46 via the first valve branch flow path 50, then enters the main flow path 48 after the valve via the second valve branch flow path 52, and finally is discharged from the second joint 28. As mentioned above, some of the fluid enters the sensor 12 from outside the filter 30 via the first sensor branch flow path 16, where the sensor 12 detects the fluid flow rate, generates a detection signal accordingly, and transmits it to the processor 60. The processor 60 controls the control valve 46 according to the detection signal to adjust the flow rate of the fluid discharged from the valve outlet 58 of the control valve 46, so that the fluid in the main flow path 48 after the valve has a predetermined flow rate.

[0018] As described above, a pressure chamber 40 and an air passage 42 are similarly provided in the pipe body 10, such that a part of the fluid in the main flow path 14 enters the pressure chamber 40 via the air passage 42. By maintaining the pressure inside and outside the sensor 12 close to each other, the probability that the sensor 12 is damaged by high-pressure fluid is reduced. [Description of Symbols]

[0019] 1 Mass flowmeter 2 Mass flow controller 10 Pipe body 12 Sensor 14 Main flow path 16 First sensor branch flow path 18 Second sensor branch flow path 20 Accommodating chamber 22 Flow path inlet 24 Flow path outlet 26 First joint 28 Second joint 30 Filter 32 Airtight ring 34 Closure 36 Inlet gas nozzle 38 Outlet gas nozzle 40 Pressure chamber 42 Air passage 44 O-ring 46 Control valve 48 Post-valve main flow path 50 First valve branch flow path 52 Second valve branch flow path 54 Partition wall 56 Valve inlet 58 Valve outlet 60 Processor

Claims

1. A pipeline body having a main channel, a first sensor branch channel, a second sensor branch channel, and a housing chamber, wherein both ends of the first sensor branch channel and the second sensor branch channel are connected to the main channel and the housing chamber, respectively, and a filter is provided in the main channel, A sensor having an inlet gas nozzle and an outlet gas nozzle, wherein the sensor is placed in a housing chamber, the inlet gas nozzle is connected to a first sensor branch channel, and the outlet gas nozzle is connected to a second sensor branch channel, and the flow rate of a fluid is measured by allowing a portion of the fluid that has passed through the main channel to enter the sensor via the first sensor branch channel, and then return to the main channel via the second sensor branch channel. A mass flow meter including, The main body of the conduit is further provided with a pressure chamber and an airway, the pressure chamber being connected to the containment chamber, and the airway being connected to the pressure chamber and the main flow path, respectively, so that a portion of the fluid that has passed through the main flow path enters the pressure chamber through the airway, thereby equalizing the pressure inside and outside the sensor. A mass flow meter in which the space between the inlet gas nozzle and the side wall of the first sensor branch passage, resulting from the diameter of the first sensor branch passage being larger than the inlet gas nozzle of the sensor, forms the airway.

2. The mass flow meter according to claim 1, wherein the space between the sensor and the side wall of the containment chamber, which is created because the volume of the containment chamber is larger than the sensor, forms the pressure chamber.

3. The mass flow meter according to claim 2, wherein an O-ring is installed on the outlet gas nozzle of the sensor so as to create an airtight seal between the pressure chamber and the second sensor branch channel.

4. Furthermore, the mass flow meter according to claim 1, further comprising a closure, the closure covering the housing chamber in which the sensor is located.

5. A pipeline body having a main channel, a first sensor branch channel, a second sensor branch channel, a housing chamber, a main channel after a valve, a first valve branch channel, and a second valve branch channel, wherein both ends of the first sensor branch channel and the second sensor branch channel are in communication with the main channel and the housing chamber, respectively, one end of the first valve branch channel is in communication with the main channel, one end of the second valve branch channel is in communication with the main channel after the valve, and a filter is provided in the main channel, A sensor having an inlet gas nozzle and an outlet gas nozzle, wherein the sensor is placed in a housing chamber, the inlet gas nozzle is connected to a first sensor branch channel, and the outlet gas nozzle is connected to a second sensor branch channel, and the sensor detects the flow rate of a fluid by allowing a portion of the fluid that has passed through the main channel to enter the sensor via the first sensor branch channel and then return to the main channel via the second sensor branch channel. A control valve having a valve inlet and a valve outlet, the control valve being installed in the main body of the pipeline, the valve inlet being connected to the first valve branch passage, and the valve outlet being connected to the second valve branch passage, so that the fluid in the main passage enters the control valve via the first valve branch passage, then enters the post-valve main passage via the second valve branch passage, and the control valve adjusts the flow rate of the fluid flowing out from the valve outlet according to the flow rate detected by the sensor. A mass flow controller including, The main body of the conduit is further provided with a pressure chamber and an airway, the pressure chamber being connected to the containment chamber, and the airway being connected to the pressure chamber and the main flow path, respectively, so that a portion of the fluid that has passed through the main flow path enters the pressure chamber through the airway, thereby equalizing the pressure inside and outside the sensor. A mass flow controller in which the space between the inlet gas nozzle and the side wall of the first sensor branch channel, resulting from the diameter of the first sensor branch channel being larger than the inlet gas nozzle of the sensor, forms the airway.

6. The mass flow controller according to claim 5, wherein the space between the sensor and the side wall of the containment chamber, which is created because the volume of the containment chamber is greater than the sensor, forms the pressure chamber.

7. The mass flow controller according to claim 5, wherein an O-ring is installed on the outlet gas nozzle of the sensor so as to create an airtight seal between the pressure chamber and the second sensor branch channel.

8. Furthermore, the mass flow controller according to claim 5, further comprising a closure, the closure covering the housing chamber in which the sensor is located.

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