CN110715697A - Flow measurement assembly with seal structure and suitable for microgram-level flow - Google Patents
Flow measurement assembly with seal structure and suitable for microgram-level flow Download PDFInfo
- Publication number
- CN110715697A CN110715697A CN201910913154.2A CN201910913154A CN110715697A CN 110715697 A CN110715697 A CN 110715697A CN 201910913154 A CN201910913154 A CN 201910913154A CN 110715697 A CN110715697 A CN 110715697A
- Authority
- CN
- China
- Prior art keywords
- measuring
- flow
- straight line
- resistor
- assembly
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Granted
Links
Images
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
- G01F1/00—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow
- G01F1/68—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow by using thermal effects
- G01F1/684—Structural arrangements; Mounting of elements, e.g. in relation to fluid flow
- G01F1/688—Structural arrangements; Mounting of elements, e.g. in relation to fluid flow using a particular type of heating, cooling or sensing element
- G01F1/69—Structural arrangements; Mounting of elements, e.g. in relation to fluid flow using a particular type of heating, cooling or sensing element of resistive type
- G01F1/692—Thin-film arrangements
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
- G01F1/00—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow
- G01F1/68—Measuring the volume flow or mass flow of fluid or fluent solid material wherein the fluid passes through a meter in a continuous flow by using thermal effects
- G01F1/684—Structural arrangements; Mounting of elements, e.g. in relation to fluid flow
- G01F1/6847—Structural arrangements; Mounting of elements, e.g. in relation to fluid flow where sensing or heating elements are not disturbing the fluid flow, e.g. elements mounted outside the flow duct
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
- G01F15/00—Details of, or accessories for, apparatus of groups G01F1/00 - G01F13/00 insofar as such details or appliances are not adapted to particular types of such apparatus
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01F—MEASURING VOLUME, VOLUME FLOW, MASS FLOW OR LIQUID LEVEL; METERING BY VOLUME
- G01F15/00—Details of, or accessories for, apparatus of groups G01F1/00 - G01F13/00 insofar as such details or appliances are not adapted to particular types of such apparatus
- G01F15/14—Casings, e.g. of special material
Landscapes
- Physics & Mathematics (AREA)
- Fluid Mechanics (AREA)
- General Physics & Mathematics (AREA)
- Measuring Volume Flow (AREA)
Abstract
The invention provides a flow measurement assembly with a sealing structure and suitable for microgram-level flow, which comprises a measurement element, a ceramic electric connector and a flow channel assembly. The measuring element is used for sensing the flow of the measured fluid, converting the flow signal into a variable resistance signal and further converting the variable resistance signal into a variable voltage analog quantity; the ceramic electric connector is used for bearing the measuring element, outputting a signal measured by the measuring element through the conductive film on the ceramic material, and simultaneously being matched with the flow channel assembly to play a role in bearing and sealing; the runner assembly carries the fluid to be measured, forms a laminar flow heat exchange channel and is matched with the ceramic electric connector. The invention has simple structure, high reliability, small size and light weight, and is suitable for high-precision measurement of microgram-grade gas.
Description
Technical Field
The invention relates to a flow measuring component with a sealing structure and suitable for microgram-level flow, belonging to the technical field of sensors,
background
The traditional flow sensor has a large flow range which is basically more than milligrams, so that the flow channel structure is designed into a flow dividing mode, and the whole gas flow is obtained by measuring the gas flow after flow dividing and calculating. The measurement method is suitable for flow measurement of milligram level or more. For microgram-level flow measurement, flow cannot be measured due to small flow rate of the flow distribution and too large pressure loss, and downstream working pressure is affected due to the adoption of flow distribution.
Disclosure of Invention
The technical problem to be solved by the invention is as follows: aiming at the defects of the prior art, the flow measurement component with the sealing structure and suitable for microgram-level flow is provided, so that the structural design with high reliability and low pressure loss is realized while the requirements of high precision and micro-flow measurement are met.
The technical scheme adopted by the invention is as follows: a flow measurement assembly adapted for microgram flow with a sealing structure, comprising: the device comprises a measuring element (1), a ceramic electric connector (2) and a flow channel assembly (3);
a flow channel assembly (3) comprising an outer housing and a fluid passage;
the measuring element (1) is used for sensing the flow of the measured fluid to form a flow signal, converting the flow signal into a voltage analog quantity and outputting the voltage analog quantity through the ceramic electric connector (2); the ceramic electric connector (2) is used for carrying the measuring element (1);
an annular runway-shaped groove is formed in the outer shell of the flow channel assembly (3), and the bottom of the groove is communicated with the fluid channel; the measuring element (1) is connected with the ceramic electric connector (2) to form a measuring unit; the measuring element (1) in the measuring unit faces to the fluid channel in the flow channel assembly (3) and extends into the fluid channel, and the measuring unit and the outer shell of the flow channel assembly (3) are sealed in an electron beam welding mode.
Preferably, the measuring element (1) comprises: four temperature sensitive resistors and eight functional ends;
the four temperature sensitive resistors are respectively a film resistor R1, a film resistor R2, a film resistor R3 and a film resistor R4;
the film resistor R1 is used as an upstream temperature measuring resistor, the film resistor R2 is used as an upstream heating resistor, the film resistor R3 is used as a downstream heating resistor, and the film resistor R4 is used as a downstream temperature measuring resistor;
the device comprises eight functional ends, namely an upstream temperature measuring resistor first measuring end, an upstream temperature measuring resistor second measuring end, an upstream heating resistor first measuring end, an upstream heating resistor second measuring end, a downstream temperature measuring resistor first measuring end, a downstream temperature measuring resistor second measuring end, a downstream heating resistor first measuring end and a downstream heating resistor second measuring end;
one end of the film resistor R1 is connected with a first measuring end of the upstream temperature measuring resistor, and the other end of the film resistor R1 is connected with a second measuring end of the upstream temperature measuring resistor;
one end of the film resistor R2 is connected with a first measuring end of the upstream heating resistor, and the other end of the film resistor R2 is connected with a second measuring end of the upstream heating resistor;
one end of the film resistor R3 is connected with a first measuring end of the downstream heating resistor, and the other end of the film resistor R3 is connected with a second measuring end of the downstream heating resistor;
one end of the film resistor R4 is connected with the first measuring end of the downstream temperature measuring resistor, and the other end of the film resistor R4 is connected with the second measuring end of the downstream temperature measuring resistor.
Preferably, the ceramic electrical connector 2 comprises: the transmission device comprises a transmission base, a welding pin and a rigid connecting ring;
a transport base comprising: a conductive thin film layer, a ceramic layer; the conductive film layer is processed on the ceramic layer;
a micropore is formed in the ceramic layer, one end of the welding needle is inserted into the micropore in a brazing mode, and the other end of the welding needle is used as a signal output end;
the rigid connecting ring is sleeved outside the transmission base and fixedly connected with the transmission base in a brazing mode;
the ceramic layer is provided with: a measurement element mounting slot;
the conductive film layer is eight signal transmission lines, each transmission line is divided into two layers, namely a nickel-chromium layer and a gold layer, the bottom surface of the nickel-chromium layer is in contact with the ceramic layer, and the gold layer is attached to the surface of the nickel-chromium layer;
one end of each of the eight signal transmission lines can be respectively connected with the eight functional ends of the measuring element (1); the other ends of the eight signal transmission lines are connected with one ends of the eight welding pins inserted into the micropores.
Preferably, the flow channel assembly (3) comprises an outer shell and a fluid channel; the outer shell is provided with a mounting hole which can be connected with the outside.
The two ends of the outer shell are provided with connecting ports which can be connected with external pipelines;
preferably, the outer casing is provided with an annular race track-shaped recess comprising: a first straight line segment, a second straight line segment, a first arc segment and a second arc segment;
one end of the first straight line segment is connected with one end of the first arc segment, the other end of the first arc segment is connected with one end of the second straight line segment, the other end of the first straight line segment is connected with one end of the second arc segment, and the other end of the second arc segment is connected with the other end of the second straight line segment.
Preferably, the fluid channel of the flow channel assembly (3) carries the fluid to be measured to form a laminar heat exchange channel.
Preferably, the ceramic electric connector (2) is used for bearing the measuring element (1), and the signal measured by the measuring element (1) is output through a conductive film layer on the ceramic material and is matched with the flow channel assembly (3) to play a role in bearing and sealing.
Preferably, the measuring element 1 is a square chip, the oval area on the chip is a measuring area, and 4 temperature sensitive resistors are arranged inside the chip; and 8 bonding pads are arranged below the chip, and the resistance signals on the chip are output.
Preferably, the ceramic material is provided with a square positioning groove.
Preferably, the transmission base of the ceramic electrical connector (2) is made of ceramic material.
Compared with the prior art, the invention has the following advantages:
(1) the invention reduces the pressure loss of the flow measuring equipment, has stable flow and small energy loss, and does not influence the downstream working pressure. The flow channel and the sealing structure are of a straight-through structure, the pressure loss is similar to a straight-through pipeline, the pressure loss is less than 0.1kPa when the full-scale flow is 100 mug/s, and the pressure loss of industrial flow measuring equipment is more than 10kPa under the condition.
(2) The invention is an integrated welding structure, and has strong bearing capacity and high reliability. The traditional thermal flow sensor is mostly carried out in an adhesive mode, the pressure bearing range is small, and the risk of leakage exists after long-term application. The structure adopts an integrated welding structure, wherein the ceramic material is connected with the kovar alloy through brazing, the kovar alloy is connected with the stainless steel material of the runner through electron beam welding of dissimilar metals, the product is pressurized by 6MPa after welding, the pressure is maintained for 5 minutes, and the leakage rate is less than 1 multiplied by 10-4Pa·L/s。
(3) The invention has simple structure, only 3 parts in the whole structure, greatly reduces the processing and assembling cost of the parts and greatly improves the reliability compared with the traditional flow measuring equipment.
Drawings
FIG. 1 is a schematic diagram of the overall configuration of a flow measurement assembly adapted for microgram flow with a sealing structure according to the present invention;
FIG. 2 is a schematic diagram of the measurement device dimensions and structure according to the present invention;
FIG. 3 is a schematic diagram of a ceramic electrical connector according to the present invention;
FIG. 4 is a schematic view of a measurement cell according to the present invention mated with a ceramic electrical connector.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings and specific embodiments.
The invention provides a flow measurement assembly with a sealing structure and suitable for microgram-level flow, which comprises a measurement element, a ceramic electric connector and a flow channel assembly. The measuring element is used for sensing the flow of the measured fluid, converting the flow signal into a variable resistance signal and further converting the variable resistance signal into a variable voltage analog quantity; the ceramic electric connector is used for bearing the measuring element, outputting a signal measured by the measuring element through the conductive film on the ceramic material, and simultaneously being matched with the flow channel assembly to play a role in bearing and sealing; the runner assembly carries the fluid to be measured, forms a laminar flow heat exchange channel and is matched with the ceramic electric connector. The invention has simple structure, high reliability, small size and light weight, and is suitable for high-precision measurement of microgram-grade gas.
The variable thrust module is used for the TQ-1 satellite propulsion subsystem, is a non-dragging propulsion system, is used for providing high-precision, low-noise and continuously adjustable thrust when space gravitational wave detection is carried out, is used for offsetting the influence of sunlight pressure and the like, and meets the requirements of high stability and high precision of an ultra-static satellite platform during working. The flow sensor is a key product of the drag-free propulsion system, is used for measuring the gas flow passing through the thruster and participates in the thrust closed-loop control. The flow measurement range is 3-100 mu g/s, the measurement precision is better than 1%, and the working pressure is 0.1 MPa. In order to accurately measure the gas flow and ensure that a rear end valve and a thruster product work normally, the fluid needs to flow stably and have low energy loss, and the downstream working pressure is not influenced. The traditional flow sensor has higher working pressure and larger flow range, and the mode that the main runner and the sub-runners of the traditional flow sensor are separately measured is suitable for measuring the flow of more than milligram level. For microgram-level flow measurement required by the TQ-1, the flow diversion causes that micro flow cannot be measured, flow is disturbed and energy loss is overlarge, so that test noise is overlarge and downstream working pressure is influenced, which is unacceptable for a variable thrust mode. Therefore, the flow measuring component with the sealing structure and suitable for microgram-grade flow is provided, the requirements of micro-flow and high precision of flow measurement by TQ-1 models are met, the component is not limited to be used on a variable thrust module of a TQ-1 satellite propulsion subsystem, and the component can be widely suitable for high-precision measurement of microgram-grade gas.
As shown in fig. 1, a flow measuring assembly with a sealing structure of the present invention suitable for microgram-class flow includes: the device comprises a measuring element (1), a ceramic electric connector (2) and a flow channel assembly (3); the measuring element (1) is used for sensing the flow of the measured fluid to form a flow signal, converting the flow signal into a voltage analog quantity and outputting the voltage analog quantity through the ceramic electric connector (2); the ceramic electric connector (2) is used for carrying the measuring element (1); a flow channel assembly (3) comprising an outer housing and a fluid passage; an annular runway-shaped groove is formed in the outer shell of the flow channel assembly (3), and the bottom of the groove is communicated with the fluid channel; the measuring element (1) is connected with the ceramic electric connector (2) to form a measuring unit; the measuring element (1) in the measuring unit faces to the fluid channel in the flow channel assembly (3) and extends into the fluid channel, and the measuring unit and the outer shell of the flow channel assembly (3) are sealed in an electron beam welding mode.
Preferably, as shown in fig. 2, the measuring element (1) is a square chip with 5mm by 3.5mm by 0.5mm, an oval area is arranged on the chip as a measuring area, and the distance from the lower edge of the chip is 3.8 mm; four temperature sensitive resistors are arranged in the measuring area; eight functional terminals are arranged below the chip.
The four temperature sensitive resistors in the measuring area of the measuring element (1) are respectively a film resistor R1, a film resistor R2, a film resistor R3 and a film resistor R4; the film resistor R1 is used as an upstream temperature measuring resistor, the film resistor R2 is used as an upstream heating resistor, the film resistor R3 is used as a downstream heating resistor, and the film resistor R4 is used as a downstream temperature measuring resistor; the film resistors R1, R2, R3 and R4 are preferably made of organic polymer films, the thickness of the organic polymer films is preferably less than 10 micrometers, and the organic polymer films are processed on a glass substrate through a film process; the resistances of the thin-film resistors R1, R2, R3, and R4 are preferably 710 Ω ± 10% (0 ℃), R2 Ω ± 10% (0 ℃), respectively, with R1 ═ R4, R3, and sensitivity accuracy is improved by matching the material preference with the resistance.
The eight functional ends on the measuring element (1) are respectively an upstream temperature measuring resistor first measuring end, an upstream temperature measuring resistor second measuring end, an upstream heating resistor first measuring end, an upstream heating resistor second measuring end, a downstream temperature measuring resistor first measuring end, a downstream temperature measuring resistor second measuring end, a downstream heating resistor first measuring end and a downstream heating resistor second measuring end; one end of the film resistor R1 is connected with a first measuring end of the upstream temperature measuring resistor, and the other end of the film resistor R1 is connected with a second measuring end of the upstream temperature measuring resistor; one end of the film resistor R2 is connected with a first measuring end of the upstream heating resistor, and the other end of the film resistor R2 is connected with a second measuring end of the upstream heating resistor; one end of the film resistor R3 is connected with a first measuring end of the downstream heating resistor, and the other end of the film resistor R3 is connected with a second measuring end of the downstream heating resistor; one end of the film resistor R4 is connected with a first measuring end of the downstream temperature measuring resistor, and the other end of the film resistor R4 is connected with a second measuring end of the downstream temperature measuring resistor; the eight functional ends on the measuring element (1) are made of gold.
As shown in fig. 3, the ceramic electrical connector (2) comprises: the transmission device comprises a transmission base, a welding pin and a rigid connecting ring; the transmission base includes: conductive film layer, ceramic layer. The conductive thin film layer on the transmission base is processed on the ceramic layer through a film process, the conductive thin film layer is eight signal transmission lines, each transmission line is preferably divided into two layers, namely a nickel-chromium layer and a gold layer, the bottom surface of the nickel-chromium layer is in contact with the ceramic layer, and the gold layer is attached to the surface of the nickel-chromium layer and used for electrically connecting the eight signal transmission ends and the eight welding pins of the measuring element (1); the ceramic layer is provided with a square positioning groove for placing a measuring element (1); eight micropores are simultaneously formed in the ceramic layer, and one ends of the eight welding pins are inserted into the eight micropores in a brazing mode.
The conductive film layer on the transmission base is eight signal transmission lines which are respectively a signal transmission line I, a signal transmission line II, a signal transmission line III, a signal transmission line IV, a signal transmission line V, a signal transmission line VI, a signal transmission line VII and a signal transmission line VIII.
The first signal transmission line comprises a first straight line section, a second straight line section, a third straight line section and a fourth straight line section; one end of a first straight line segment is connected with a first functional end of the eight functional ends of the measuring element (1), the other end of the first straight line segment is connected with one end of a second straight line segment, the other end of the second straight line segment is connected with one end of a third straight line segment, the other end of the third straight line segment is connected with one end of a fourth straight line segment, and the other end of the fourth straight line segment is connected with one end of a first welding needle of the eight welding needles inserted into the micropore; the first straight line section is aligned and parallel to the first functional end of the measuring element (1), the second straight line section is perpendicular to the first straight line section, and the third straight line section is perpendicular to the second straight line section; the fourth straight line segment is perpendicular to the third straight line segment.
The signal transmission line II comprises a first straight line section, a second straight line section and a third straight line section; one end of the first straight line segment is connected with the second functional end of the eight functional ends of the measuring element (1), the other end of the first straight line segment is connected with one end of the second straight line segment, the other end of the second straight line segment is connected with one end of the third straight line segment, and the other end of the third straight line segment is connected with one end of a second welding needle of the eight welding needles inserted into the micropore; the first straight line section is aligned and parallel to the second functional end of the measuring element (1), the second straight line section is perpendicular to the first straight line section, and the third straight line section is perpendicular to the second straight line section.
The signal transmission line III comprises a first straight line section, a second straight line section, a third straight line section and a fourth straight line section; one end of the first straight line segment is connected with the third functional end of the eight functional ends of the measuring element (1), the other end of the first straight line segment is connected with one end of the second straight line segment, the other end of the second straight line segment is connected with one end of the third straight line segment, the other end of the third straight line segment is connected with one end of the fourth straight line segment, and the other end of the fourth straight line segment is connected with one end of the insertion micropore of the third welding needle of the eight welding needles; the first straight line section is aligned and parallel to the third functional end of the measuring element (1), the second straight line section is perpendicular to the first straight line section, and the third straight line section is perpendicular to the second straight line section; the fourth straight line segment is perpendicular to the third straight line segment.
The signal transmission line four comprises a first straight line section, a second straight line section, a third straight line section and a fourth straight line section; one end of the first straight line segment is connected with the fourth functional end of the eight functional ends of the measuring element (1), the other end of the first straight line segment is connected with one end of the second straight line segment, the other end of the second straight line segment is connected with one end of the third straight line segment, the other end of the third straight line segment is connected with one end of the fourth straight line segment, and the other end of the fourth straight line segment is connected with one end of a fourth welding needle of the eight welding needles inserted into the micropore; the first straight line section is aligned and parallel to the fourth functional end of the measuring element (1), the second straight line section is perpendicular to the first straight line section, and the third straight line section is perpendicular to the second straight line section; the fourth straight line segment is perpendicular to the third straight line segment.
The signal transmission line V comprises a first straight line section, a second straight line section, a third straight line section and a fourth straight line section; one end of the first straight line segment is connected with the fifth functional end of the eight functional ends of the measuring element (1), the other end of the first straight line segment is connected with one end of the second straight line segment, the other end of the second straight line segment is connected with one end of the third straight line segment, the other end of the third straight line segment is connected with one end of the fourth straight line segment, and the other end of the fourth straight line segment is connected with one end of the fifth welding needle of the eight welding needles inserted into the micropore; the first straight line section is aligned and parallel to the fifth functional end of the measuring element (1), the second straight line section is perpendicular to the first straight line section, and the third straight line section is perpendicular to the second straight line section; the fourth straight line segment is perpendicular to the third straight line segment.
The signal transmission line six comprises a first straight line section, a second straight line section, a third straight line section and a fourth straight line section; one end of the first straight line segment is connected with the sixth functional end of the eight functional ends of the measuring element (1), the other end of the first straight line segment is connected with one end of the second straight line segment, the other end of the second straight line segment is connected with one end of the third straight line segment, the other end of the third straight line segment is connected with one end of the fourth straight line segment, and the other end of the fourth straight line segment is connected with one end of the sixth welding needle of the eight welding needles inserted into the micropore; the first straight line section is aligned and parallel to the sixth functional end of the measuring element (1), the second straight line section is perpendicular to the first straight line section, and the third straight line section is perpendicular to the second straight line section; the fourth straight line segment is perpendicular to the third straight line segment.
The signal transmission line seventh comprises a first straight line section, a second straight line section and a third straight line section; one end of the first straight line segment is connected with the seventh functional end of the eight functional ends of the measuring element (1), the other end of the first straight line segment is connected with one end of the second straight line segment, the other end of the second straight line segment is connected with one end of the third straight line segment, and the other end of the third straight line segment is connected with one end of a seventh welding needle of the eight welding needles inserted into the micro-hole; the first straight line section is aligned and parallel to the seventh functional end of the measuring element (1), the second straight line section is perpendicular to the first straight line section, and the third straight line section is perpendicular to the second straight line section.
The signal transmission line eighth comprises a first straight line segment, a second straight line segment, a third straight line segment and a fourth straight line segment; one end of the first straight line segment is connected with the eighth functional end of the eight functional ends of the measuring element (1), the other end of the first straight line segment is connected with one end of the second straight line segment, the other end of the second straight line segment is connected with one end of the third straight line segment, the other end of the third straight line segment is connected with one end of the fourth straight line segment, and the other end of the fourth straight line segment is connected with one end of the eighth welding needle of the eight welding needles inserted into the micropore; the first straight line section is aligned and parallel to the eighth functional end of the measuring element (1), the second straight line section is perpendicular to the first straight line section, and the third straight line section is perpendicular to the second straight line section; the fourth straight line segment is perpendicular to the third straight line segment.
The distances between the first straight line segments of the eight signal transmission lines and the square positioning grooves are preferably 0.15-0.35 mm, the lengths of the first straight line segments are preferably equal to or larger than 0.5mm, the widths of the first straight line segments are preferably 0.2mm, and the first straight line segments correspond to the positions and the sizes of the eight functional ends of the measuring element (1) one by one.
The ceramic layer on the transmission base is preferably in an annular runway shape and comprises a first straight line section, a second straight line section, a first arc line section and a second arc line section; one end of the first straight line segment is connected with one end of the first arc segment, the other end of the first arc segment is connected with one end of the second straight line segment, the other end of the first straight line segment is connected with one end of the second arc segment, and the other end of the second arc segment is connected with the other end of the second straight line segment. The lengths of the first straight line section and the second straight line section are both 11mm, the radiuses of the first arc line section and the second arc line section are both 6.5mm, the thickness of the ceramic layer is 3mm, the size of the square positioning groove on the ceramic layer is 5 mm-3.5 mm-0.5 mm, and the distance between the lower edge of the square positioning groove and the edge of the ceramic layer is 2.7 mm.
The material of the eight welding pins is preferably kovar alloy 4J29, nickel plating and gold plating are carried out on the surfaces of the eight welding pins, one ends of the welding pins are inserted into the micropores in a brazing mode and are conducted with the eight signal transmission lines, and the other ends of the welding pins are used as signal output ends;
the rigid connecting ring is made of Kovar alloy 4J29 preferably, is sleeved on the outer side of the transmission base and is fixedly connected with the transmission base through brazing. The rigid connecting ring is a T-shaped circular ring and comprises an outer ring and an inner ring; the thickness of the outer ring is preferably 1mm, and the outer ring is matched with the outer shell of the runner assembly (3); the inner ring is 3mm in thickness and fixedly connected with the ceramic layer through brazing, and the pressure resistance and the sealing property are improved through the above preferred scheme.
The outer ring of the rigid connecting ring is in an annular runway shape and comprises a first straight line section, a second straight line section, a first arc line section and a second arc line section; one end of the first straight line segment is connected with one end of the first arc segment, the other end of the first arc segment is connected with one end of the second straight line segment, the other end of the first straight line segment is connected with one end of the second arc segment, and the other end of the second arc segment is connected with the other end of the second straight line segment. The lengths of the first straight line segment and the second straight line segment are both preferably 11mm, and the radiuses of the first arc line segment and the second arc line segment are both preferably 8.5 mm;
the inner ring of the rigid connecting ring is in an annular runway shape and comprises a first straight line section, a second straight line section, a first arc line section and a second arc line section; one end of the first straight line segment is connected with one end of the first arc segment, the other end of the first arc segment is connected with one end of the second straight line segment, the other end of the first straight line segment is connected with one end of the second arc segment, and the other end of the second arc segment is connected with the other end of the second straight line segment. The lengths of the first straight line segment and the second straight line segment are both 11mm, and the radiuses of the first arc segment and the second arc segment are both 7.5 mm. The shape of the annular runway is further limited by the sizes of the inner ring and the outer ring, so that the rigid connecting ring is more closely matched with the transmission base, and the sealing performance is further improved.
A flow channel assembly (3) comprising an outer housing and a fluid passage. The outer shell is preferably provided with 8 studs, and internal threads are arranged inside the outer shell and can be connected with an external circuit board; the two ends of the outer shell are provided with connecting ports which can be connected with external pipelines; the outer shell is provided with an annular runway-shaped groove for placing the ceramic electric connector (2); the fluid channel carries the measured fluid to form a laminar heat exchange channel.
An annular race track shaped recess of the outer housing comprising: a first straight line segment, a second straight line segment, a first arc segment and a second arc segment; one end of the first straight line segment is connected with one end of the first arc segment, the other end of the first arc segment is connected with one end of the second straight line segment, the other end of the first straight line segment is connected with one end of the second arc segment, and the other end of the second arc segment is connected with the other end of the second straight line segment. The length of the first straight line segment and the length of the second straight line segment are both preferably 11mm, and the radius of the first arc line segment and the radius of the second arc line segment are both preferably 8.5 mm. Through the parameters, the annular runway-shaped groove of the outer shell and the rigid connecting ring realize better matching and sealing performance.
The material of the flow channel assembly (3) is preferably stainless steel 316L.
As shown in fig. 4, the measuring element (1) is placed in the middle of the square positioning slot of the ceramic electrical connector (2), and the oval measuring area of the measuring element (1) is located in the central axis of the ceramic electrical connector (2); eight functional ends of the measuring element (1) are connected with first straight line ends of eight signal transmission lines of the ceramic electric connector (2), and signals are output through eight welding pins of the ceramic electric connector (2).
The measuring element (1) is connected with the ceramic electric connector (2) to form a measuring unit shown in figure 4, and is placed in a groove in the shape of an annular runway on the outer shell of the flow channel assembly (3) shown in figure 1, the bottom of the groove is communicated with the fluid channel, and the measuring element (1) faces the fluid channel in the flow channel assembly (3) and extends into the fluid channel. The rigid connection ring of the ceramic electrical connector (2) in the measuring unit and the outer housing of the flow channel assembly (3) are preferably sealed by means of electron beam welding.
The invention relates to a flow measurement component with a sealing structure and suitable for microgram-level flow, which is based on a thermal temperature difference measurement principle, wherein two heating resistors R2 and R3 are arranged in the center of a measurement element (1), two temperature measuring resistors R1 and R4 are respectively arranged at the upstream and downstream of gas, when no gas flows through, the temperature fields are symmetrically distributed, and the resistance values of the upstream and downstream temperature measuring resistors R1 and R4 are the same; when airflow flows, a difference value occurs between the upstream temperature measuring resistor R1 and the downstream temperature measuring resistor R4, and the gas flow detection can be realized by detecting the difference value.
In practice, gas is introduced into the oval measuring area of the measuring cell (1) through the fluid passage of the flow channel assembly (3) in fig. 1. When the gas flow changes, the resistance values R1-R4 of four resistors in the oval temperature measuring area of the measuring element (1) change, and the resistance value changes and is output to eight signal transmission lines of the ceramic electric connector (2) through eight functional ends on the measuring element (1) and then is output to eight welding pins of the ceramic electric connector (2), so that signal output is realized.
The invention further scheme for realizing the improvement of the measurement precision is as follows: the thickness of the measuring element (1) is set to be D1, the depth of a groove of the ceramic electric connector (2) is set to be D2, the dispensing thickness of the measuring element (1) and the groove is set to be D3, the optimal constraint condition that the thickness of the dispensing point is-0.05 mm and is less than D1+ D2-D3 and less than 0.05mm is met, and the further improvement of the measuring precision can be realized.
The further scheme for realizing the improvement of the measurement reliability comprises the following steps: if the radiuses of the first arc line section and the second arc line section of the annular runway-shaped groove of the outer shell of the flow channel assembly (3) are R1, the radiuses of the first arc line section and the second arc line section of the outer ring of the rigid connecting ring of the ceramic electric connector (2) are R2, and the radiuses of 0mm < R1-R2<0.0034mm are met, namely the gap between the welding line of the flow channel assembly (3) and the electron beam welding of the ceramic electric connector (2) is smaller than 0.0034mm, the optimal constraint condition is met, and the further improvement of the measurement reliability can be realized.
The invention calculates the fluid flow state in the fluid channel of the flow channel component (3) preferably:
the flow measurement range is 0-100 mug/s, and trial calculation is carried out by adopting the upper flow limit Q as 100 mug/s. The fluid medium is selected from nitrogen at 25 ℃ under 0.1MPa, and has physical properties of density of 1.14kg/m3 and dynamic viscosity of 17.812 mu Pa & s.
Calculating the equivalent diameter of the section at the center of the bottom of the flow channel:
wherein: a is the area of the flow cross section; and S is the perimeter of the contact between the fluid and the solid on the flow cross section.
Converting the flow into the bottom flow velocity:
wherein: v is the fluid mean velocity; ρ is the fluid density.
The reynolds number can be calculated as:
wherein: v is the fluid mean velocity; ρ is the fluid density; mu is dynamic viscosity; d is the characteristic length of the pipeline.
From the above calculation, it can be judged that the flow in the fluid passage of the flow path member (3) is a laminar flow.
2) Calculating the length L of a heat exchange inlet section:
L＝0.05×Re×d＝0.05×0.675×0.586×10-3m＝0.02mm
in order to obtain laminar heat exchange, the length L of an inlet section in a fluid channel of the flow channel component (3) is more than 0.02 mm.
In addition, the engineering usually takes:
calculating the length L of the heat exchange inlet section as follows:
L≈10×d＝10×0.586×10-3m＝5.86mm
therefore, the length of the heat exchange inlet section of the fluid channel of the flow channel assembly (3) is designed to be 6mm, and the condition of laminar flow generation is met.
The flow measuring assembly with the sealing structure and suitable for microgram-level flow reduces pressure loss of flow measuring equipment, is stable in flow and low in energy loss, and does not affect downstream working pressure. The pressure loss test, the precision test, the verification pressure test and the external leakage rate detection are carried out in the process of the invention, and the test results are as follows:
(1) and (3) pressure loss test: the flow measuring component with the sealing structure and suitable for microgram-level flow is of a straight-through structure, the pressure loss is similar to that of a straight-through pipeline, the pressure loss is less than 0.1kPa when the flow is 100 microgram/s in a full range, and the pressure loss of industrial flow measuring equipment is more than 10kPa under the condition, so that the structure greatly reduces the pressure loss, the flow is stable and the downstream working pressure is not influenced;
(2) and (3) testing the precision: the flow measurement component with the sealing structure and suitable for microgram-level flow is subjected to flow calibration test, and the flow measurement precision is superior to 1%;
(3) and (3) verifying a pressure test: the invention is an integrated welding structure, and has strong bearing capacity and high reliability. The flow measuring component with the sealing structure and suitable for microgram-level flow is pressurized for 6MPa, and is kept for 5 minutes without abnormality, and the pressure is far higher than the verification pressure of 0.2MPa required by a satellite;
(4) and (3) detecting the leakage rate: the flow measuring component with the sealing structure and suitable for microgram-level flow adopts a vacuum leakage detection method, pressurizes the components at 0.2MPa and detects the leakage rate of the components at 7 multiplied by 10 through a helium mass spectrometer-5Pa.L/s, 1 × 10 better than that of satellite-4Pa·L/s。
It should be noted that, the contents that are not described in detail in this specification can be realized by those skilled in the art through the description in this specification and the prior art, and therefore, the details are not described herein.
The above description is only a preferred embodiment of the present invention, and is not intended to limit the scope of the present invention. For a person skilled in the art, without inventive step, several modifications and alterations of the present invention are possible, all of which are intended to be covered by the scope of the present invention.
Claims (10)
1. A flow measurement assembly suitable for microgram-level flow with a sealing structure, comprising: the device comprises a measuring element (1), a ceramic electric connector (2) and a flow channel assembly (3);
a flow channel assembly (3) comprising an outer housing and a fluid passage;
the measuring element (1) is used for sensing the flow of the measured fluid to form a flow signal, converting the flow signal into a voltage analog quantity and outputting the voltage analog quantity through the ceramic electric connector (2); the ceramic electric connector (2) is used for carrying the measuring element (1);
an annular runway-shaped groove is formed in the outer shell of the flow channel assembly (3), and the bottom of the groove is communicated with the fluid channel; the measuring element (1) is connected with the ceramic electric connector (2) to form a measuring unit; the measuring element (1) in the measuring unit faces to the fluid channel in the flow channel assembly (3) and extends into the fluid channel, and the measuring unit and the outer shell of the flow channel assembly (3) are sealed in an electron beam welding mode.
2. The flow measuring assembly with the sealing structure suitable for microgram-scale flow rate of claim 1, wherein: measuring element (1) comprising: four temperature sensitive resistors and eight functional ends;
the four temperature sensitive resistors are respectively a film resistor R1, a film resistor R2, a film resistor R3 and a film resistor R4;
the film resistor R1 is used as an upstream temperature measuring resistor, the film resistor R2 is used as an upstream heating resistor, the film resistor R3 is used as a downstream heating resistor, and the film resistor R4 is used as a downstream temperature measuring resistor;
the device comprises eight functional ends, namely an upstream temperature measuring resistor first measuring end, an upstream temperature measuring resistor second measuring end, an upstream heating resistor first measuring end, an upstream heating resistor second measuring end, a downstream temperature measuring resistor first measuring end, a downstream temperature measuring resistor second measuring end, a downstream heating resistor first measuring end and a downstream heating resistor second measuring end;
one end of the film resistor R1 is connected with a first measuring end of the upstream temperature measuring resistor, and the other end of the film resistor R1 is connected with a second measuring end of the upstream temperature measuring resistor;
one end of the film resistor R2 is connected with a first measuring end of the upstream heating resistor, and the other end of the film resistor R2 is connected with a second measuring end of the upstream heating resistor;
one end of the film resistor R3 is connected with a first measuring end of the downstream heating resistor, and the other end of the film resistor R3 is connected with a second measuring end of the downstream heating resistor;
one end of the film resistor R4 is connected with the first measuring end of the downstream temperature measuring resistor, and the other end of the film resistor R4 is connected with the second measuring end of the downstream temperature measuring resistor.
3. The flow measuring assembly with the sealing structure suitable for microgram-scale flow rate of claim 1, wherein: ceramic electrical connector 2 comprising: the transmission device comprises a transmission base, a welding pin and a rigid connecting ring;
a transport base comprising: a conductive thin film layer, a ceramic layer; the conductive film layer is processed on the ceramic layer;
a micropore is formed in the ceramic layer, one end of the welding needle is inserted into the micropore in a brazing mode, and the other end of the welding needle is used as a signal output end;
the rigid connecting ring is sleeved outside the transmission base and fixedly connected with the transmission base in a brazing mode;
the ceramic layer is provided with: a measurement element mounting slot;
the conductive film layer is eight signal transmission lines, each transmission line is divided into two layers, namely a nickel-chromium layer and a gold layer, the bottom surface of the nickel-chromium layer is in contact with the ceramic layer, and the gold layer is attached to the surface of the nickel-chromium layer;
one end of each of the eight signal transmission lines can be respectively connected with the eight functional ends of the measuring element (1); the other ends of the eight signal transmission lines are connected with one ends of the eight welding pins inserted into the micropores.
4. The flow measuring assembly with the sealing structure suitable for microgram-scale flow rate of claim 1, wherein: a flow channel assembly (3) comprising an outer housing and a fluid passage; the outer shell is provided with a mounting hole which can be connected with the outside;
the both ends of shell body are equipped with the connector, can be connected with outside pipeline.
5. The flow measuring assembly with the sealing structure suitable for microgram-scale flow rate of claim 1, wherein: the annular runway shape's that the shell body was equipped with recess includes: a first straight line segment, a second straight line segment, a first arc segment and a second arc segment;
one end of the first straight line segment is connected with one end of the first arc segment, the other end of the first arc segment is connected with one end of the second straight line segment, the other end of the first straight line segment is connected with one end of the second arc segment, and the other end of the second arc segment is connected with the other end of the second straight line segment.
6. The flow measuring assembly with the sealing structure suitable for microgram-scale flow rate of claim 1, wherein: the fluid channel of the flow channel assembly (3) carries the measured fluid to form a laminar heat exchange channel.
7. The flow measuring assembly with the sealing structure suitable for microgram-scale flow rate of claim 1, wherein: the ceramic electric connector (2) is used for bearing the measuring element (1), outputs a signal measured by the measuring element (1) through a conductive film layer on the ceramic material, and is matched with the flow channel assembly (3) to play a role in bearing and sealing.
8. The flow measuring assembly with the sealing structure suitable for microgram-scale flow rate of claim 1, wherein: the measuring element 1 is a square chip, an oval area on the chip is a measuring area, and 4 temperature sensitive resistors are arranged inside the chip; and 8 bonding pads are arranged below the chip, and the resistance signals on the chip are output.
9. The flow measuring assembly with the sealing structure suitable for microgram-scale flow rate of claim 1, wherein: the ceramic material is provided with a square positioning groove.
10. The flow measuring assembly with the sealing structure suitable for microgram-scale flow rate of claim 1, wherein: the transmission base of the ceramic electric connector (2) is made of ceramic materials.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201910913154.2A CN110715697B (en) | 2019-09-25 | 2019-09-25 | Flow measurement assembly with seal structure and suitable for microgram-level flow |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| CN201910913154.2A CN110715697B (en) | 2019-09-25 | 2019-09-25 | Flow measurement assembly with seal structure and suitable for microgram-level flow |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| CN110715697A true CN110715697A (en) | 2020-01-21 |
| CN110715697B CN110715697B (en) | 2021-02-09 |
Family
ID=69210888
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CN201910913154.2A Active CN110715697B (en) | 2019-09-25 | 2019-09-25 | Flow measurement assembly with seal structure and suitable for microgram-level flow |
Country Status (1)
| Country | Link |
|---|---|
| CN (1) | CN110715697B (en) |
Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101393044A (en) * | 2007-09-20 | 2009-03-25 | 株式会社山武 | Flow sensor unit |
| US20100122658A1 (en) * | 2008-11-14 | 2010-05-20 | Michael Long | Metering of particulate material and vaporization thereof |
| CN102711882A (en) * | 2010-01-20 | 2012-10-03 | 皇家飞利浦电子股份有限公司 | Method of using a temperature-based aerosol detector |
| JP2017116316A (en) * | 2015-12-22 | 2017-06-29 | 株式会社デンソー | Air flow rate measuring device |
| CN109579928A (en) * | 2018-11-23 | 2019-04-05 | 北京控制工程研究所 | A kind of hot type micro-flow measurement sensor flow passage and sealing structure |
-
2019
- 2019-09-25 CN CN201910913154.2A patent/CN110715697B/en active Active
Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101393044A (en) * | 2007-09-20 | 2009-03-25 | 株式会社山武 | Flow sensor unit |
| US20100122658A1 (en) * | 2008-11-14 | 2010-05-20 | Michael Long | Metering of particulate material and vaporization thereof |
| CN102711882A (en) * | 2010-01-20 | 2012-10-03 | 皇家飞利浦电子股份有限公司 | Method of using a temperature-based aerosol detector |
| JP2017116316A (en) * | 2015-12-22 | 2017-06-29 | 株式会社デンソー | Air flow rate measuring device |
| CN109579928A (en) * | 2018-11-23 | 2019-04-05 | 北京控制工程研究所 | A kind of hot type micro-flow measurement sensor flow passage and sealing structure |
Non-Patent Citations (2)
| Title |
|---|
| S. NARASIMHAN ; A. BAR-COHEN ; R. NAIR: "Flow and pressure field characteristics in the porous block compact modeling of parallel plate heat sinks", 《IEEE TRANSACTIONS ON COMPONENTS AND PACKAGING TECHNOLOGIES》 * |
| 彭杰纲,周兆英,叶雄英: "基于MEMS技术的微型流量传感器的研究进展", 《力学进展》 * |
Also Published As
| Publication number | Publication date |
|---|---|
| CN110715697B (en) | 2021-02-09 |
Similar Documents
| Publication | Publication Date | Title |
|---|---|---|
| JP5260817B2 (en) | Flow module and integrated flow restrictor | |
| CN107436205B (en) | On-chip temperature compensation graphene pressure sensor | |
| US6945106B2 (en) | Mass flowmeter | |
| US7121139B2 (en) | Thermal mass flow rate sensor having fixed bypass ratio | |
| CN110274648B (en) | Gas flow sensor with gas composition correction | |
| US20130319105A1 (en) | Micro flow sensor | |
| CN109964102B (en) | Airflow sensor with thermal conductivity and thermal diffusivity sensing | |
| EP3995789A1 (en) | Flow sensing device | |
| Zhu et al. | Development of a self-packaged 2D MEMS thermal wind sensor for low power applications | |
| WO2011071932A1 (en) | Kinetic flow meter | |
| CN110715697B (en) | Flow measurement assembly with seal structure and suitable for microgram-level flow | |
| US11473951B2 (en) | Flow direction sensor | |
| US8640552B2 (en) | MEMS airflow sensor die incorporating additional circuitry on the die | |
| US10018489B2 (en) | Miniature differential pressure flow sensor | |
| CN209878208U (en) | MEMS Pirani vacuum gauge | |
| EP3719453B1 (en) | Integrated sensor apparatus with pressure sensing element and flow sensing element | |
| CN106680363B (en) | Bridge arm thermosensitive element and processing method thereof, and magnetic pressure type oxygen detector | |
| CN112649103A (en) | Chip temperature measurement system based on thin film metal thermal resistor | |
| Ned et al. | High accuracy, high temperature pressure probes for aerodynamic testing | |
| Fournier et al. | SMD pressure and flow sensor for compressed air in LTCC technology with integrated electronics | |
| US9188494B2 (en) | Measurement of fluid temperatures | |
| Luo et al. | Anemometer with three-dimensional directionality for detection of very low speed air flow and acoustic particle velocity detecting capability | |
| EP4235132A1 (en) | Pressure and temperature sensor | |
| CN116773049A (en) | Ceramic bolt for high temperature heat flow measurement | |
| Sheppard et al. | Fabrication and testing of a MEMS low-flow meter |
Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PB01 | Publication | ||
| PB01 | Publication | ||
| SE01 | Entry into force of request for substantive examination | ||
| SE01 | Entry into force of request for substantive examination | ||
| GR01 | Patent grant | ||
| GR01 | Patent grant |