WO2019127870A1

WO2019127870A1 - Impeller, centrifugal compressor and fuel cell system

Info

Publication number: WO2019127870A1
Application number: PCT/CN2018/076402
Authority: WO
Inventors: 许承; 肖育民; 徐焕恩
Original assignee: 北京伯肯节能科技股份有限公司
Priority date: 2017-12-26
Filing date: 2018-02-12
Publication date: 2019-07-04
Also published as: CN107989823B; CN107989823A

Abstract

An impeller, a centrifugal compressor and a fuel cell system. The impeller (10) comprises: a hub (11), which is substantially recessed truncated cone shaped and has a truncated cone shaped curved surface; the truncated cone shaped curved surface defines a spin axis of the hub (11); the thin end of the hub (11) is an air inlet end and the large end is an air outlet end; and a plurality of big vanes (12) and a plurality of small vanes (13) extending from the truncated cone shaped curved surface are arranged at certain intervals around the spin axis of the hub (11); as shown in the axial projection drawing of the impeller (10), the outermost edge of the big vanes (12) and the small vanes (13) with respect to the spin axial form an impeller meridian plane exit angle between -15 degrees and 15 degrees with the spin axial.

Description

Impeller, centrifugal compressor and fuel cell system

Technical field

The present invention relates to an impeller, a centrifugal compressor having an impeller, and a fuel cell system having a centrifugal compressor, particularly a fuel cell system for a vehicle.

Background technique

A fuel cell is a power generation device that directly converts the chemical energy of a fuel and an oxidant into electrical energy by an electrochemical reaction. Because fuel cells have many advantages unmatched by conventional batteries, such as high power generation efficiency, low environmental pollution, low noise, and wide fuel range, they have been widely used in recent years in such industries as automotive industry, energy generation, shipbuilding, aerospace, and home. Power and other industries.

Electrochemical reactions in fuel cells are a complex process in which the oxidant is typically oxygen or air. Studies have shown that the pressure of oxygen in the fuel cell is directly related to the performance of the fuel cell system. Increasing the air supply pressure (ie, the partial pressure of oxygen) can increase the energy density of the fuel cell system. In addition, increasing the supply pressure of the fuel cell can also reduce the size of the system, reduce the water content in the air, and maintain the water balance in the fuel cell. Therefore, there is a need in the fuel cell system for a gas supply subsystem dedicated to providing high pressure air to the fuel cell. At present, an impeller centrifugal compressor is generally used as a gas supply subsystem of a fuel cell system.

Impeller centrifugal compressors typically include an impeller, an impeller shroud, and an electric motor. The rotating shaft of the impeller is fixed with the rotating shaft of the motor and rotates with the rotating shaft. During the operation of the compressor system, as the motor drives the impeller to rotate, the air enters the impeller in the axial direction, and the energy is transmitted to the air through the rotation of the impeller, and the air is statically pressurized. Energy and kinetic energy, as the impeller rotates radially away from the impeller and into the downstream diffuser, the air is decelerated in the diffuser, and the kinetic energy is converted to static pressure, further increasing the pressure. The pressurized air exits the compressor and is humidified by the humidifier and eventually enters the fuel cell passage. Since the impeller is constantly rotating, the air can be continuously pressurized and pushed out, thereby maintaining a continuous flow of gas in the compressor.

For the existing centrifugal compressor, the volume is large and the structure is not compact enough, and it is still necessary to improve and improve in terms of improving the full load efficiency, maintaining the efficiency in the flow range, reducing the size of the whole machine and reducing the number of parts.

Summary of the invention

The present invention is directed to the above problems in the prior art, and provides an impeller, a centrifugal compressor having the same, and a fuel cell system using the centrifugal compressor.

According to an embodiment of the invention, the impeller comprises: a hub having a generally concave truncated cone shape and having a frustoconical curved surface defining a rotational axis of the hub, the thin end of the hub being an air inlet end a thick end is an air outlet end; a plurality of large blades and a plurality of small blades spaced apart from a rotation axis of the hub extending from the frustoconical curved surface; wherein, on the axial projection view of the impeller, the large blade and the small blade An impeller meridian exit angle of between -15 degrees and 15 degrees is formed between the outermost edge of the blade relative to the axis of rotation of the hub and the axis of rotation of the hub.

According to an embodiment of the present invention, the streamline cross-sectional shape of the large blade is S-shaped, and the streamline cross-sectional shape of the small blade is C-shaped.

According to an embodiment of the invention, the ratio of the radius of curvature of the large and small blades to the diameter of the outlet end of the hub is between 0.5 and 2.

According to an embodiment of the invention, the large and small blades are evenly arranged around the axis of rotation of the hub.

According to one embodiment of the invention, the bottom of the hub is provided with a sealing structure that forms a seal with the backing plate in the centrifugal compressor.

According to an embodiment of the present invention, the sealing structure of the hub is a circular boss or an annular boss extending downward from the bottom of the hub, and a radial direction is provided on the circumferential surface of the circular boss or the annular boss. a plurality of annular sealing teeth projecting outward.

According to an embodiment of the invention, the diameter of the circular boss or annular boss is between 50% and 95% of the diameter of the outlet end of the hub, and the axial thickness of the circular boss or annular boss is between 4 and Between 8 mm, the number of annular sealing teeth is 3 to 6.

According to an embodiment of the invention, the diameter of the circular boss or annular boss is 75% of the diameter of the outlet end of the hub, and the axial thickness of the circular boss or annular boss is between 5 mm, the annular sealing teeth The number is six.

According to an embodiment of the invention, the sealing teeth are in the shape of a zigzag having a tip angle of between 50 and 75 degrees.

According to an embodiment of the invention, the shape of the sealing teeth is curved.

According to an embodiment of the invention, the impeller has a machining accuracy Ra of less than 1.6 microns.

The present invention also provides a centrifugal compressor comprising: the impeller according to any one of claims 1 to 10; an electric motor for powering rotation of the impeller; and a backing plate fixed to the motor housing; An impeller shaft that passes through the back plate and is fixed to a motor shaft of the motor, the impeller is fixed on the impeller shaft to rotate with the impeller shaft; the impeller guard is fixed on the back plate and the impeller is located between the back plate and the back plate Wherein, the sealing structure of the impeller forms a seal with the back plate, and the impeller shaft is integral with the motor shaft.

According to an embodiment of the invention, the backing plate is integral with the housing of the electric motor.

According to one embodiment of the invention, there is an interference fit between the impeller and the impeller shaft.

According to an embodiment of the invention, the end of the impeller shaft has a threaded portion, and the nut is screwed onto the threaded portion to fix the impeller on the impeller shaft, wherein the direction of rotation of the impeller is opposite to the direction in which the nut is loosened.

According to an embodiment of the present invention, the impeller shroud includes: an axial intake port disposed at a center position of the impeller shroud; a tangential exhaust pipe disposed at a peripheral position of the impeller shroud; and a plurality of bolt mounting portions Provided at a peripheral position of the impeller shroud and corresponding to the position of the bolt mounting portion on the back plate and the motor casing, so that the impeller shroud, the back plate and the motor casing can be simultaneously fixed by bolts; The plurality of bolt mounting portions are unevenly distributed around the periphery of the impeller shroud.

According to an embodiment of the invention, the shape of the exhaust pipe is a combination of a straight line and a quadratic curve.

According to one embodiment of the invention, the frustoconical curved surface of the hub and the surface of the backing plate are smoothly transitioned.

The present invention also provides a fuel cell system including the centrifugal compressor and the filtration device, the fuel cell stack, the cooling system, the humidifier, the hydrogen supply system, the hydrogen recovery device, the control system, and the like according to the above embodiments.

According to the impeller of the present invention, the blades are arranged in such a manner that the relative diffusion speed of the gas discharge is more uniform, and the nominal diameter thereof is less than the maximum diameter of the multistage centrifugal compressor blades at the same flow rate and pressure ratio. According to the centrifugal compressor of the present invention, since the impeller shaft is integral with the motor shaft, and the impeller, the impeller shroud and the motor are assembled together, the structure is more compact, the centrifugal compressor is smaller in size, and the number of parts is reduced. Significantly reduced production and maintenance costs.

DRAWINGS

For a better understanding of the above and other objects, features, advantages and functions of the present invention, reference may be made to the preferred embodiments shown in the drawings. The same reference numerals in the drawings denote the same parts. The drawings are intended to be illustrative of the preferred embodiments of the invention,

1A-1C illustrate an impeller in accordance with a preferred embodiment of the present invention;

2A-2B show exemplary axial projection views of a blade of an impeller in accordance with a preferred embodiment of the present invention, wherein FIG. 2A shows a case where the impeller meridian exit angle is positive, and FIG. 2B shows an impeller meridian outlet. When the angle is negative;

Figure 3 is a partial enlarged view of Figure 1B showing the sealing structure of the impeller;

4A-4B illustrate a centrifugal compressor in accordance with a preferred embodiment of the present invention;

Figure 5 is a partial enlarged view of Figure 4B showing the manner of fixing between the impeller and the impeller shaft;

6A-6B illustrate an impeller shroud in accordance with a preferred embodiment of the present invention;

Figure 7 is another partial enlarged view of Figure 4B showing the consistent transition between the frustoconical curved surface of the hub and the surface of the backing plate.

Detailed ways

Hereinafter, an impeller of the present invention, a centrifugal compressor having the same, and a fuel cell system using the centrifugal compressor will be described in detail with reference to the accompanying drawings. The invention is described in terms of a preferred embodiment of the invention, and other ways in which the invention can be practiced on the basis of the preferred embodiments are also contemplated.

The orientation terms appearing in the following detailed description, such as "upper", "lower", "left", "right", etc., refer to the orientations in the particular figures.

1A-1C show a side view, a cross-sectional view, and a top view, respectively, of an impeller 10 in accordance with a preferred embodiment of the present invention. As shown, the impeller 10 includes a hub 11 and a plurality of vanes extending from the hub 11. Therein, it can be seen from FIG. 1B that the hub 11 is substantially concave in shape and has a frusto-conical curved surface S from which a plurality of large blades 12 and a plurality of small blades 13 extend. And spaced apart on the surface about the axis of rotation AA of the impeller or hub, ie, as shown in FIG. 1C, each large blade 12 is located between two adjacent small blades 13, each small blade 13 being located Between two adjacent large blades 12. Referring to Fig. 1B, the upper end of the hub 11 is the air inlet end, the lower end is the outlet end after air pressurization, and the outlet end has a radius r ₁ . Wherein, the cross section of each of the large blades 12 and each of the small blades 13 taken along the respective flow lines is a streamline section, and each of the large blades 12 has an S shape in its streamline section, and each of the small blades 13 is in its flow. The shape in the line section is C-shaped.

2A-2B exemplarily show the axial projection view of the blade, which can be seen by the axial projection view, the impeller meridian exit angle of each blade is α, and the impeller meridian exit angle refers to the axial projection of the blade. The angle formed between the outermost edge of the axis AA and the axis AA, in a preferred embodiment according to the invention, the impeller meridian exit angle a is between -15 and 15 degrees. The case where the impeller meridian exit angle α is a positive value is shown in Fig. 2A, and when the impeller meridian exit angle α is a negative value, the angle is in the opposite direction as shown in Fig. 2B. Here, the axial projection view of the impeller needs to be described. In the art, since the impeller is a revolving body that rotates around the axis, the shape of the impeller and the blade is usually described by a cylindrical coordinate system. The so-called "axial surface (also called meridian surface) By "plane" through the axis of the impeller (in the present invention, axis AA), the axial projection map refers to a pattern formed by rotating each point on the blade about the axis AA onto the axial surface.

In a preferred embodiment according to the invention, the ratio of the radius of curvature at different points of the large blade 12 and the small blade 13 to the outlet end diameter 2r ₁ of the hub 11 is between 0.5 and 2.

In a preferred embodiment according to the present invention, the large blade 12 and the small blade 13 are evenly arranged around the axis A-A in an amount of eight pieces, of course, the number is not limited thereto, and may be more or less.

1A and 1B, in a preferred embodiment according to the present invention, the bottom of the hub 11 is provided with a sealing structure 14 which forms a seal with the backing plate in the centrifugal compressor, thereby reducing the thrust bearing in the centrifugal compressor. The thrust that it is subjected to. Further, the sealing structure 14 may be a circular boss extending downward from the bottom of the hub 11, and a plurality of annular sealing teeth 141 protruding outward in the radial direction are disposed on the circumferential surface of the circular boss. Wherein the radius of the circular boss is r ₂ , the diameter 2r _{2 is} between 50% and 95% of the diameter of the outlet end of the hub 2r ₁ , and the axial thickness H of the circular boss is between 4 and 8 mm Between the number of annular sealing teeth is 3 to 6.

In a further embodiment according to the invention, the diameter 2r _{2 of the} circular boss may be 75% of the diameter 2r ₁ of the outlet end of the hub, the axial thickness H of the circular boss may be 5 mm, and the annular sealing teeth 141 The number can be six.

In other embodiments according to the present invention, the sealing structure 14 may not be a circular boss but an annular boss, and a plurality of annular sealing teeth 141 protruding radially outward as described above may be disposed on the outer circumference of the annular boss To the face.

As shown in FIG. 3, in a preferred embodiment according to the present invention, the sealing teeth 141 have a zigzag shape with a tip angle β of between 50 and 75 degrees. Of course, the shape of the sealing teeth can also be other shapes, such as an arc.

In a preferred embodiment according to the invention, the impeller has a surface roughness Ra of less than 1.6 microns.

In another aspect, the invention also provides a centrifugal compressor. As shown in FIGS. 4A-4B, a centrifugal compressor according to a preferred embodiment of the present invention includes the impeller 10 according to the above embodiment, and further includes an electric motor 20 for powering the rotation of the impeller 10, further, centrifuging The compressor further includes: a back plate 30 fixed to or integrally formed with the motor housing 22; an impeller shaft 40 that passes through the back plate 30 and is fixed to the motor shaft 21 of the motor or integrally formed with the motor shaft 21, and the impeller 10 Fixed to the impeller shaft 40 for rotation therewith; and impeller shroud 50 secured to the backing plate 30 and between the impeller 10 and the backing plate 30; wherein, as previously described, the sealing structure of the impeller 10 A seal is formed between the 14 and the backing plate 30.

In a preferred embodiment in accordance with the invention, there is an interference fit between the impeller 10 and the impeller shaft 40. In a further preferred embodiment of the present invention, as shown in FIG. 5, the end of the impeller shaft 40 has a threaded portion on which the nut 41 is screwed to fix the impeller 10 on the impeller shaft 40, in order to prevent The nut 41 is loosened during use. Preferably, the release direction of the nut 41 is set to be opposite to the direction of rotation of the impeller 10, so that the nut 41 is not only not loosened, but will become more and more used with the use of the centrifugal compressor. tight.

In a preferred embodiment in accordance with the present invention, as shown in Figures 6A-6B, the impeller shroud 50 includes an axial air inlet 51 for air inflow at its central portion, generally tangentially disposed at its peripheral portion. An exhaust pipe 52 that facilitates air pressure and flows out; and a plurality of bolt mounting portions 53 that are disposed at a peripheral position of the impeller shroud 50. When the impeller shroud is mounted on the centrifugal compressor, the bolt mounting portion 53 The position coincides with the position of the bolt mounting portion on the back plate 30 and the motor casing 22, so that the impeller shroud 50, the back plate 30, and the motor casing 22 can be fixed together by the bolt passing therethrough. Further, as shown in FIG. 6B, the plurality of bolt mounting portions 53 are unevenly distributed around the impeller shroud 50, which can function to position the exhaust pipe 52 relative to the centrifugal compressor and prevent Installation error.

In a preferred embodiment in accordance with the invention, the shape of the exhaust pipe 52 is a combination of a straight line and a quadratic curve.

As can be seen from Figure 4B, the backing plate 30 is devoid of vanes such that the outer raised portion 54 of the impeller shroud 50 forms a vaneless diffuser portion with the backing plate 30, as the gas flows through the passage of the diffuser portion due to the flow As the cross-section of the channel increases, the flow velocity of the gas molecules in the front decreases, and the gas molecules in the back flow continuously to the gas molecules in front, so that most of the kinetic energy of the gas is converted into static pressure energy, which further plays a role of supercharging. As shown in Figure 7, in a further preferred embodiment according to the invention, the frustoconical curved surface S of the hub smoothly transitions to the surface of the backing plate 30, in other words the contour of the hub 11 towards the leafless diffuser portion The wall profile is smooth and the two are substantially uniform or aligned, and air can smoothly flow from the impeller to the diffuser section, which optimizes the diffuser of the diffuser section.

In still another aspect, the present invention provides a fuel cell system including the centrifugal compressor and the filtration device, the fuel cell stack, the cooling system, the humidifier, the hydrogen supply system, the hydrogen recovery device, and the control system according to the above embodiments. Wait.

The scope of the invention is defined only by the claims. Those skilled in the art will readily appreciate that alternative configurations of the disclosed structures can be considered as possible alternative embodiments, and the disclosed embodiments can be combined to produce new embodiments. They also fall within the scope of the appended claims.

Claims

An impeller, characterized in that the impeller comprises:

a hub having a generally concave truncated cone shape and having a frusto-conical curved surface defining an axis of rotation of the hub, the thin end of the hub being an air inlet end and the thick end being air Export end

a plurality of large blades and a plurality of small blades spaced apart from an axis of rotation of the hub extending from the frustoconical curved surface;

Wherein, on the axial projection view of the impeller, an impeller meridian between -15 degrees and 15 degrees between the outermost edge of the large blade and the small blade with respect to the rotation axis and the rotation axis is formed Face exit angle.
The impeller according to claim 1, wherein each of the large blades and each of the small blades is a streamlined section taken along a respective streamline, and each of the large blades has an S-shape in a streamlined section thereof. Each small vane has a C-shape in its streamline cross section.
The impeller according to claim 2, wherein a ratio of a radius of curvature of the large and small blades to a diameter of an outlet end of the hub is between 0.5 and 2.
The impeller according to claim 3, wherein the large and small blades are evenly arranged around an axis of rotation of the hub.
The impeller according to claim 4, wherein the bottom of the hub is provided with a sealing structure, and a sealing structure of the hub forms a seal with a backing plate in the centrifugal compressor.
The impeller according to claim 5, wherein the sealing structure of the hub is a circular boss or annular boss extending downward from the bottom of the hub, at the circular boss or annular boss The circumferential surface is provided with a plurality of annular sealing teeth projecting radially outward.
The impeller according to claim 6, wherein said circular boss or annular boss has a diameter between 50% and 95% of the diameter of the outlet end of said hub, said circular boss or The annular boss has an axial thickness of between 4 and 8 mm and the number of annular sealing teeth is from 3 to 6.
The impeller according to claim 7, wherein said circular boss or annular boss has a diameter of 75% of the diameter of the outlet end of said hub, and the axial direction of said circular boss or annular boss The thickness is between 5 mm and the number of the annular sealing teeth is six.
The impeller according to claim 8, wherein said sealing teeth have a zigzag shape with a tip angle of between 50 and 75 degrees.
The impeller according to claim 8, wherein the sealing teeth are arcuate in shape.
The impeller according to claim 9, wherein said impeller has a machining accuracy Ra of less than 1.6 μm.
A centrifugal compressor, characterized in that the centrifugal compressor comprises:

An impeller according to any of claims 1-11;

a motor for powering the rotation of the impeller;

a back plate fixed to the motor housing;

An impeller shaft passing through the back plate and fixed to a motor shaft of the motor, the impeller being fixed on the impeller shaft to rotate with the impeller shaft;

An impeller shroud secured to the backing plate with the impeller positioned between it and the backing plate;

Wherein, the sealing structure of the impeller forms a seal with the back plate, and the impeller shaft is integrated with the motor shaft.
The centrifugal compressor according to claim 12, wherein said backing plate is integral with a casing of the motor.
The centrifugal compressor according to claim 12, wherein an interference fit between the impeller and the impeller shaft is provided.
The centrifugal compressor according to claim 14, wherein said impeller shaft end has a threaded portion, and a nut is screwed on said threaded portion to fix the impeller on the impeller shaft, wherein the impeller is rotated It is opposite to the loosening direction of the nut.
The centrifugal compressor according to claim 12, wherein said impeller shroud comprises:

An axial air inlet disposed at a center of the impeller shroud;

a tangential exhaust pipe disposed at a peripheral position of the impeller shroud;

a plurality of bolt mounting portions disposed at a peripheral position of the impeller shroud and corresponding to positions of the bolt mounting portions on the back plate and the motor housing, so that the impeller shroud, the back plate, and the motor housing can be simultaneously fixed by bolts Together

Wherein, the plurality of bolt mounting portions are unevenly distributed around the periphery of the impeller shroud.
The centrifugal compressor according to claim 16, wherein the shape of the exhaust pipe is a combination of a straight line and a quadratic curve.
The centrifugal compressor according to claim 17, wherein the frustoconical curved surface of the hub and the surface of the backing plate are smoothly transitioned.
A fuel cell system comprising the centrifugal compressor of any of claims 12-18.