CN111720348A

CN111720348A - Special turbine fan for breathing machine and impeller machining process

Info

Publication number: CN111720348A
Application number: CN202010559636.5A
Authority: CN
Inventors: 戴学利; 张英俊; 张元顶; 张炜; 高永操; 李传仓; 张赢权
Original assignee: Bahuan Technology Group Co ltd
Current assignee: Bahuan Technology Group Co ltd
Priority date: 2020-06-18
Filing date: 2020-06-18
Publication date: 2020-09-29
Anticipated expiration: 2040-06-18
Also published as: CN111720348B

Abstract

The invention relates to the field of medical instruments, and particularly discloses a special turbofan for a breathing machine and a processing technology of an impeller. The turbine fan comprises a shell, an impeller and a driving motor, wherein a confluence region is arranged in the shell and is communicated with the pressurizing space; the converging region comprises a large end and a small end, and the sectional area of the converging region is gradually increased from the small end to the large end; the impeller comprises a base plate and a front cover, a plurality of turbine blades are arranged between the base plate and the front cover, each turbine blade comprises a main blade and an auxiliary blade, and the main blades and the auxiliary blades are distributed at intervals in the circumferential direction; the main blade and the auxiliary blade extend from the high-pressure outlet to the low-pressure inlet, and the length of the auxiliary blade in the radial direction is smaller than that of the main blade in the radial direction. The turbofan adopts the single-stage impeller, not only can meet the core performance requirement required by the breathing machine, but also has the advantages of high response speed, low noise and the like.

Description

Special turbine fan for breathing machine and impeller machining process

Technical Field

The invention relates to the field of medical instruments, in particular to a special turbofan for a breathing machine and a processing technology of an impeller.

Background

The breathing machine is a medical device which can replace, control or change the spontaneous respiration of a person, prevent and treat respiratory failure, reduce complications and save and prolong the life of a patient. The turbo fan is a core component of the respirator, is a source of therapeutic gas, and is used for conveying the gas by increasing the pressure of the gas, so that the spontaneous respiratory function of a patient is improved or replaced, and the respiratory failure is treated.

The performance index of the turbofan directly influences the performance of the ventilator, and in order to achieve the effect of replacing breathing, the core parameter requirements of the ventilator comprise outlet static pressure and flow, wherein the outlet static pressure is not less than 10kPa, and the flow is not less than 400L/min. With the development of miniaturization, portability and intellectualization of respirators, the requirements on the external dimensions are higher and higher while the core performance parameters of the turbofan are ensured, for example, in the portable respirator, the installation space reserved for the turbofan is limited, the length of the turbofan is required to be less than 100mm, and the diameter is not more than 65 mm. How to ensure sufficient outlet pressure and air flow in a limited space is the biggest difficulty in designing a turbofan for a respirator.

In order to achieve the performance parameters, a multi-stage fan mode is usually adopted in a common ventilator in the current market, although the multi-stage fan mode can ensure the static pressure at an outlet and the air flow parameters, the multi-stage fan mode inevitably leads to longer response time of equipment due to complex structure, and the integral working noise of the ventilator is higher due to complex installation of an air path and an impeller, so that the defect of larger noise still exists.

Disclosure of Invention

The technical problem to be solved by the invention is to provide a special turbofan for a breathing machine and an impeller processing technology, wherein the turbofan adopts a single-stage impeller, not only can meet the core performance requirement required by the breathing machine, but also has the advantages of high response speed, low noise and the like.

In order to solve the technical problems, the technical scheme provided by the invention is as follows: a special turbofan for a respirator comprises a shell, an impeller and a driving motor, wherein the shell comprises an upper shell and a lower shell, the upper shell and the lower shell enclose a pressurizing space, and the impeller is arranged in the pressurizing space; the center of the upper shell is provided with an air inlet communicated with the pressurizing space, and the driving motor is connected with the lower shell and drives the impeller to rotate relative to the shell;

the impeller comprises a base plate and a front cover, a plurality of turbine blades are arranged between the base plate and the front cover, and the outlet setting angle of the turbine blades is 29.1 degrees +/-0.3 degrees; a pressurizing air passage is formed between every two adjacent turbine blades; the front cover is provided with a low-pressure inlet corresponding to the air inlet, the outer edge of the pressurizing air passage is a high-pressure outlet, and the height of the pressurizing air passage is gradually reduced from the low-pressure inlet to the high-pressure outlet;

the turbine blade comprises a main blade and an auxiliary blade, and the main blade and the auxiliary blade are distributed at intervals in the circumferential direction; the main blade extends from the low-pressure inlet to the high-pressure outlet, the auxiliary blade extends from the high-pressure outlet to the low-pressure inlet, and the length of the auxiliary blade in the radial direction is 1/2-2/3 of the diameter of the impeller;

the blade comprises an equal-thickness section close to the high-pressure outlet and a variable-thickness section close to the low-pressure inlet, the thickness of the equal-thickness section is 1.2 +/-0.1 mm, and the thickness of the variable-thickness section is gradually reduced from one end connected with the equal-thickness section to the other end; the circular arc diameter of the windward side of the equal-thickness section is 27.5 +/-0.1 mm, and the circular arc diameter of the windward side of the variable-thickness section is 41 +/-0.1 mm;

the end parts of the main blades corresponding to the low-pressure inlet are arranged in an inclined mode relative to the vertical direction, and the inclination angle is 30.2 degrees +/-0.1 degree;

the height of the air channel is gradually reduced from the low-pressure inlet to the high-pressure outlet, and the minimum inclination angle of the inner wall of the front cover relative to the inner wall of the base plate is 15 degrees.

In order to realize the core performance parameters specified by the breathing machine in a limited space, the idea of the application is to improve the rotating speed of the impeller and redesign the structure of the impeller under the requirement of high-speed operation, and the specific effects are as follows:

1. the outlet setting angle is 29.1 degrees +/-0.3 degrees; the turbine blade comprises a main blade and an auxiliary blade, wherein the main blade and the auxiliary blade are distributed at intervals in the circumferential direction. Through the interval setting of main blade and auxiliary blade, guaranteed the quantity of blade, reduce the clearance between two adjacent blades, and then allow less export angle of laying, under the prerequisite of size and rotational speed, guarantee the transport efficiency to the air, improve export flow and pressure. Meanwhile, the impeller is small in size, and the main blades and the auxiliary blades are arranged differently, so that the number of the blades at a low-pressure inlet can be reduced, and the sufficient air inlet section size is ensured.

2. The turbine blade comprises an equal-thickness section and a variable-thickness section, and the sectional form is adopted, so that the structural strength of the high-pressure region blade is ensured, and the air circulation area of a low-pressure region is also considered.

3. The circular arc diameter of the windward side of the equal-thickness section is 27.5 +/-0.1 mm, and the circular arc diameter of the windward side of the variable-thickness section is 41 +/-0.1 mm; the two sizes are reasonably matched to form a complete windward side of the blade, so that the highest efficiency of the impeller when acting can be ensured.

4. The design of single-stage impellers is adopted, and compared with multi-stage impellers, the vibration is small, the operation is more stable, the air outlet quantity is stable, the air circulation condition is improved, and the occurrence probability of turbulent flow is reduced. Meanwhile, the internal structure is simplified, so that the pressurization response time of the fan is greatly reduced.

5. The end parts of the main blades corresponding to the low-pressure inlet are obliquely arranged relative to the vertical direction, the inclination angle is 30.2 degrees +/-0.1 degrees, and smooth air inlet of the impeller is facilitated.

6. The height of the air channel is gradually reduced from the low-pressure inlet to the high-pressure outlet, and the minimum inclination angle of the inner wall of the front cover relative to the inner wall of the base plate is 15 degrees, so that the impeller is favorable for pressurizing air.

Preferably, a confluence region annularly arranged around the pressurizing space is further arranged in the shell, and the confluence region is communicated with the pressurizing space; the converging region comprises a large end and a small end, and the large end of the converging region is communicated with the air outlet; the sectional area of the confluence area is gradually increased from a small end to a large end, and a guide line with the gradually-changed sectional area of the confluence area is an Archimedes spiral line; the minimum clearance between the outer edge of the confluence area and the outer edge of the impeller is 0.3-0.5 mm.

The air cushions the gathering at the district that converges after impeller pressurization, then discharges from the gas outlet along the extending direction in the district that converges, and better concentration and water conservancy diversion are gaseous, prevent to produce the turbulent flow at the air flue, make the transport of air current more smooth and easy, and are more high-efficient.

Preferably, the cross-sectional area of the flow merging region is "C" shaped, and the "C" shaped opening of the flow merging region is disposed toward the pressurizing space.

Preferably, the clearance between the impeller and the upper shell is 0.5-0.8 mm, and the clearance between the impeller and the lower shell is 1.5-2.0 mm. Meanwhile, the sealing performance and the noise performance are considered, the backflow of high-pressure gas is reduced, and the noise is reduced.

Preferably, the driving motor is a high-speed permanent magnet brushless direct current motor, the operation is stable, and the high-speed performance is good.

The processing technology of the impeller at least comprises the following steps:

selecting organic materials, and integrally forming a front cover and a turbine blade by adopting an injection molding process, wherein the turbine blade comprises a main blade and an auxiliary blade;

in the molding process, at least two turbine blades are selected, and positioning lugs are machined on the end faces, far away from the front cover, of the corresponding turbine blades;

selecting the same materials as the first step, and forming the substrate by adopting an injection molding process;

in the forming process or after the forming is finished, processing positioning grooves corresponding to the turbine blades one by one and positioning holes corresponding to the positioning lugs one by one on the substrate;

inserting the positioning lug into the positioning hole until the turbine blade is inserted into the positioning groove, and positioning the blade and the substrate;

and step four, applying pretightening force between the turbine blade and the substrate, and simultaneously completing welding between the turbine blade and the substrate in an ultrasonic welding mode.

The impeller is small in size, multiple in blade quantity, complex in structure, high in precision requirement and high in machining difficulty. In the first step, the front cover and the turbine blade are integrally formed, so that the machining precision and the relative connection precision of the turbine blade and the front cover can be well guaranteed; simultaneously, because the turbine blade is kept away from the one end opening of protecgulum, detect for the centre of turbine blade and provide the space, improve the yields of product.

In the third step, the positioning lug and the positioning hole are used as positioning guide, and the turbine blade and the positioning groove are used for accurate positioning, so that the mounting accuracy of the turbine blade and the substrate is improved; meanwhile, the positioning lug is inserted into the positioning hole, so that the bearing effect can be achieved, the connection reliability is improved, and the structural stability at high rotating speed is ensured.

And in the fourth step, ultrasonic welding is adopted, so that the problem of small operation space is well avoided.

Preferably, during the injection molding in the first step, a triangular rib is machined on the end face, away from the front cover, of each turbine blade, and the triangular rib partially or completely covers the end face of the turbine blade on which the triangular rib is arranged. In the process of ultrasonic welding, the triangular convex ribs are melted and filled, so that the connection reliability is ensured, and meanwhile, the mounting precision is improved.

Preferably, after the first step is completed, the machining precision of the turbine blade is detected, and the detection parameters comprise an outlet placement angle, the thickness of the turbine blade, the arc radius of the windward side and the blade distribution gap.

Drawings

FIG. 1 is a schematic structural diagram of a dedicated turbofan for a ventilator according to the present embodiment;

FIG. 2 is a sectional view of a special turbine fan for a ventilator according to the present embodiment;

FIG. 3 is an enlarged view of a portion of FIG. 2 at B;

FIG. 4 is a top view of a lower housing of a special turbofan for a ventilator according to the present embodiment;

FIG. 5 is a sectional view of an impeller of a turbofan dedicated to a ventilator according to an embodiment;

FIG. 6 is a top view of an impeller of a special turbofan for a ventilator according to the present embodiment;

FIG. 7 is a graph illustrating the performance of a dedicated turbofan for the ventilator of the present embodiment;

FIG. 8 is a bottom view of a finished product of a processing step I of an impeller of the special turbofan for the ventilator according to the present embodiment;

FIG. 9 is a sectional view taken along line F-F of FIG. 8;

FIG. 10 is a side view of a first step in the process for machining the impeller of the turbofan specifically adapted for use with the ventilator of the present embodiment;

fig. 11 is a top view of a finished product of a second step of the impeller processing process in the special turbofan for the ventilator according to the present embodiment.

Detailed Description

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

Examples

As shown in fig. 1 and 2, a special turbofan for a ventilator includes a housing 1, an impeller 3 and a driving motor 2, where the driving motor 2 is a high-speed permanent magnet brushless dc motor, and has stable operation and good high-speed performance. The casing 1 comprises an upper casing 15 and a lower casing 14, a pressurizing space is enclosed in the upper casing 15 and the lower casing 14, and the impeller 3 is arranged in the pressurizing space. The center of the upper shell 15 is provided with an air inlet 12 communicated with the pressurizing space, and the driving motor 2 is connected with the lower shell 14 and drives the impeller 3 to rotate relative to the shell 1. The clearance between the impeller 3 and the upper shell 15 is 0.5-0.8 mm (as shown by d in fig. 3), and the clearance between the impeller 3 and the lower shell 14 is 1.5-2.0 mm (as shown by b in fig. 3).

As shown in fig. 2 to 4, a confluence region 13 annularly surrounding the pressurizing space is further provided in the housing 1, and the confluence region 13 is communicated with the pressurizing space. The converging region 13 comprises a large end and a small end, the large end of the converging region 13 is communicated with the air outlet 11, the sectional area of the converging region 13 is gradually increased from the small end to the large end, and a guide line with the gradually-changed sectional area of the converging region 13 is an Archimedes spiral line. As shown at 16 in fig. 4, the director of the merge region is defined, and the formula of the archimedean spiral corresponding to the director is ρ =24.7+6.86 × θ/360. The cross-sectional area of the confluence region 13 is "C" shaped, and the "C" shaped opening of the confluence region 13 is arranged toward the pressurizing space. The minimum clearance between the outer edge of the confluence area 13 and the outer edge of the impeller 3 is 0.3-0.5 mm (as shown in c in fig. 3).

As shown in fig. 5 and 6, the impeller 3 includes a base plate 32 and a front cover 31, a plurality of turbine blades 33 are disposed between the base plate 32 and the front cover 31, and an outlet setting angle of the turbine blades 33 is 29.1 ° ± 0.3 °, which is shown as α in fig. 5. A pressurizing air channel 36 is formed between every two adjacent turbine blades 33, a low-pressure inlet 34 corresponding to the air inlet 12 is arranged on the front cover 31, a high-pressure outlet 35 is arranged at the outer edge of the pressurizing air channel 36, the height of the pressurizing air channel 36 is gradually reduced from the low-pressure inlet 34 to the high-pressure outlet 35, and the minimum inclination angle of the inner wall of the front cover 31 relative to the inner wall of the base plate 32 is 15 degrees, namely, the included angle is r shown in fig. 4.

As shown in fig. 5 and 6, the turbine blade 33 includes a main blade 37 and a secondary blade 38, and the main blade 37 and the secondary blade 38 are circumferentially spaced apart. The main blade 37 extends from the low-pressure inlet 34 to the high-pressure outlet 35, the auxiliary blade 38 extends from the high-pressure outlet 35 to the low-pressure inlet 34, and the length of the auxiliary blade 38 in the radial direction is 1/2-2/3 of the diameter of the impeller 3. The end of said main vane 37 corresponding to the low pressure inlet 34 is inclined with respect to the vertical by an angle of 30.2 ° ± 0.1 °, i.e. by the angle β shown in fig. 4.

As shown in fig. 5 and 6, the vane includes a constant thickness section near the high pressure outlet 35 and a variable thickness section near the low pressure inlet 34, which is a boundary line between the constant thickness section and the variable thickness section as shown at a in fig. 5. The thickness of the equal-thickness section is 1.2 +/-0.1 mm, and the thickness of the variable-thickness section is gradually reduced from one end connected with the equal-thickness section to the other end. The diameter of the arc of the windward side of the equal-thickness section is 27.5 +/-0.1 mm (shown as R1 in figure 5), and the diameter of the arc of the windward side of the variable-thickness section is 41 +/-0.1 mm (shown as R2 in figure 5).

By adopting the scheme, particularly the structure of the impeller 3, the core performance parameter requirement of the breathing machine can be realized when the rotating speed of the motor is controlled at 50000r/min, the diameter of the impeller 3 can be controlled within 50mm at the moment, the height of the impeller 3 is controlled at 13mm, and sufficient space is reserved for the design of the matching interface on the motor and the shell 1.

Fig. 7 is a performance curve diagram of the turbo fan when the motor rotates at 50000r/min, and it can be clearly seen from the diagram that the maximum static pressure value of the turbo fan reaches more than 11kPa, the maximum flow reaches 470L/min, and the efficiency can reach more than 50% when the normal tidal volume of the breathing machine is 200L/min, which completely meets the use requirement of the breathing machine and has higher efficiency.

A process for machining an impeller 3 as described above, comprising at least the following steps:

as shown in fig. 8-10, selecting engineering plastics, preferably PA6 engineering plastics required for medical use, and integrally forming the front cover 31 and the turbine blade 33 by using an injection molding process, wherein the turbine blade 33 comprises a main blade 37 and a secondary blade 38;

in the molding process, at least two turbine blades 33 are selected, and positioning lugs 331 are machined on the end faces, far away from the front cover 31, of the corresponding turbine blades 33;

meanwhile, a triangular rib 332 is machined on the end face of each turbine blade 33 far away from the front cover 31, and the triangular rib 332 partially or completely covers the end face of the turbine blade 33. In the process of ultrasonic welding, the triangular convex ribs 332 are melted and filled, so that the connection reliability is ensured, and meanwhile, the mounting precision is improved.

After the forming is completed, the machining precision of the turbine blade 33 is detected, and the detection parameters include an outlet placement angle, the thickness of the turbine blade 33, the arc radius of the windward side and the blade distribution gap.

Step two, selecting the same material as the step one, and forming the substrate 32 by adopting an injection molding process;

during or after the molding process, positioning grooves 321 corresponding to the turbine blades 33 one by one and positioning holes 322 corresponding to the positioning projections 331 one by one are formed in the base plate 32. As shown in fig. 11.

In the third step, the positioning protrusion 331 is inserted into the positioning hole 322 until the turbine blade 33 is inserted into the positioning slot 321, thereby completing the positioning of the blade and the substrate 32.

Step four, pre-tightening force is applied between the turbine blade 33 and the base plate 32, and meanwhile welding between the turbine blade 33 and the base plate 32 is completed in an ultrasonic welding mode.

In conclusion, the above description is only for the preferred embodiment of the present invention and should not be construed as limiting the present invention, and any modification, equivalent replacement, and improvement made within the spirit and principle of the present invention should be included in the protection scope of the present invention.

Claims

1. The utility model provides a dedicated turbofan of breathing machine, includes casing, impeller and driving motor, its characterized in that: the shell comprises an upper shell and a lower shell, a pressurizing space is enclosed by the upper shell and the lower shell, and the impeller is arranged in the pressurizing space; the center of the upper shell is provided with an air inlet communicated with the pressurizing space, and the driving motor is connected with the lower shell and drives the impeller to rotate relative to the shell;

the impeller comprises a base plate and a front cover, a plurality of turbine blades are arranged between the base plate and the front cover, and the outlet setting angle of the turbine blades is 29.1 degrees +/-0.3 degrees; a pressurizing air passage is formed between every two adjacent turbine blades; the front cover is provided with a low-pressure inlet corresponding to the air inlet, and the outer edge of the pressurizing air passage is a high-pressure outlet;

the blade comprises an equal-thickness section close to the high-pressure outlet and a variable-thickness section close to the low-pressure inlet, the thickness of the equal-thickness section is 1.2 +/-0.1 mm, and the thickness of the variable-thickness section is gradually reduced from one end connected with the equal-thickness section to the other end; the circular arc diameter of the windward side of the equal-thickness section is 42.5 +/-0.05 mm, and the circular arc diameter of the windward side of the variable-thickness section is 13.7 +/-0.05 mm;

2. The turbofan of claim 1 wherein: a confluence region annularly arranged around the pressurizing space is also arranged in the shell, and the confluence region is communicated with the pressurizing space; the converging region comprises a large end and a small end, and the large end of the converging region is communicated with the air outlet; the sectional area of the confluence area is gradually increased from a small end to a large end, and a guide line with the gradually-changed sectional area of the confluence area is an Archimedes spiral line; the minimum clearance between the outer edge of the confluence area and the outer edge of the impeller is 0.3-0.5 mm.

3. The turbofan of claim 2 wherein: the sectional area of the confluence area is C-shaped, and the C-shaped opening of the confluence area is arranged towards the pressurizing space.

4. The turbofan of claim 1 wherein: the clearance between the impeller and the upper shell is 0.5-0.8 mm, and the clearance between the impeller and the lower shell is 1.5-2.0 mm.

5. The turbofan of claim 1 wherein: the driving motor is a high-speed permanent magnet brushless direct current motor.

6. A process for machining an impeller as claimed in any one of claims 1 to 5, characterized in that it comprises at least the following steps:

selecting engineering plastics, and integrally forming a front cover and a turbine blade by adopting an injection molding process, wherein the turbine blade comprises a main blade and an auxiliary blade;

7. The impeller machining process according to claim 6, wherein: and step one, machining a triangular convex rib on the end surface of each turbine blade far away from the front cover while performing injection molding, wherein the triangular convex rib partially or completely covers the end surface of the turbine blade.

8. The impeller machining process according to claim 6 or 9, characterized in that: and after the first step is finished, detecting the machining precision of the turbine blade, wherein the detection parameters comprise an outlet placement angle, the thickness of the turbine blade, the arc radius of the windward side and the blade distribution gap.