Impeller with zigzag wheel cover and fan

Abstract

The invention discloses a sawtooth-shaped wheel cover impeller and a draught fan. The sawtooth-shaped wheel cover impeller comprises a shaft disc, an impeller cover and an impeller cover, the wheel disc is fixedly installed on the shaft disc, and the axis of the wheel disc and the axis of the shaft disc are collinear; one end of each blade in the blade group is fixed on the end surface of one end of the wheel disc and overhangs towards one side far away from the wheel disc; the blades are annularly arrayed by taking the shaft of the wheel disc as an array shaft, and blade channels are formed among the blades; the wheel cover is used for union of the overhanging ends of the blades and is provided with an air inlet, and the air inlet and the axis of the wheel cover are collinear with the axis of the wheel disc; the rim of the wheel cover is in a tooth shape, and the tooth height of the contained teeth is not smaller than one third of the radial dimension of a cover body of the wheel cover and not larger than three fifths of the radial dimension of the cover body of the wheel cover. Under the condition that the weight reduction effect is relatively good, the impeller with the sawtooth-shaped impeller cover still has good overall rigidity.

Description

Technical Field

[0001] The invention relates to an impeller equipped with a fan, and also relates to a fan equipped with the impeller. Background Art

[0002] For example, centrifugal fans are one of the most widely used fans, and their uses are widespread in all areas of the national economy, such as ventilation, dust removal and cooling in factories, mines, tunnels, cooling towers, vehicles, ships and buildings; ventilation and draft in boilers and industrial furnaces; cooling and ventilation in air conditioning equipment and household appliances; drying and selection of grains; inflation and propulsion of air ducts and hovercraft, etc. Due to its extremely wide range of applications and a wide range of size distribution, it also leads to different requirements for strength, etc.

[0003] When it comes to strength, you need to first understand the basic principles and structure of centrifugal fans. Centrifugal fans rely on input mechanical energy to rotate the impeller, accelerate the gas introduced from the center hole at one end of the casing and increase the gas pressure, thereby changing the flow direction and delivering the gas in parallel. It can be seen that the rotating impeller is the core component of the fan, and its strength, stiffness and manufacturing process are particularly important for fan manufacturing.

[0004] The impeller usually includes a shaft disk, which is used to assemble the impeller on the main shaft of the fan. The shaft disk is similar to the hub sleeve of the wheel hub, and a wheel disk is installed on the shaft disk. The wheel disk is mainly used to extend the radial dimension of the impeller to adapt to fans of different sizes. Then a group of blades are provided. In the axial direction of the shaft disk, one end of the blade is fixedly mounted on the wheel disk, and the other end is connected by a wheel cover. The impeller of this structure is also called a closed impeller to distinguish it from an open impeller. The open impeller is equivalent to omitting the wheel disk and the wheel cover relative to the closed impeller. There is also a kind of impeller between the open impeller and the closed impeller, which can be called a semi-open impeller, which does not have a wheel cover relative to the closed impeller. The present invention belongs to a closed impeller, and has the aforementioned wheel disk and wheel cover.

[0005] From the above description, it can be seen that the wheel disc uses the shaft disc as the mounting base, and the blades use the wheel disc as the mounting base. The blades are cantilevered axially of the shaft disc in a cantilevered manner, and the end of the overhang is connected with a wheel cover. This kind of overhang will inevitably be affected by the weight of the blade group and the wheel cover. If the weight of the blade group or the wheel cover is relatively small, the load on the shaft disc will be relatively small.

[0006] Among them, the blade group is the main functional component, which cooperates with the wheel cover and the wheel disc to form a centrifugal channel. The wheel cover is a disc-shaped structure with an air inlet. The airflow enters through the air inlet and then is discharged through the centrifugal channel. The centrifugal channel should be relatively stable. Although the wheel cover does not play a supporting role, its connecting effect can make the impeller a whole and reduce the flutter of the blades during the rotation of the impeller. Therefore, there will be certain difficulties in reducing the weight of the blades or the wheel cover. Although the wheel cover itself mainly plays a connecting role and is also used to construct the centrifugal air duct, its own strength should not be too small. This has been a technical problem that has been difficult to solve in this field for a long time. Summary of the invention

[0007] According to an embodiment of the present invention, a serrated wheel cover impeller having good overall stiffness while having a relatively good weight reduction effect is provided. In an embodiment of the present invention, a fan equipped with the serrated wheel cover impeller is also provided.

[0008] According to a first aspect of an embodiment of the present invention, a sawtooth cover impeller is provided, the basic components of which include: Axle disc; A wheel disc, fixedly mounted on the shaft disc, wherein the axis of the wheel disc is colinear with the axis of the shaft disc; A blade group, wherein one end of a blade in the blade group is fixed to an end surface of one end of the wheel disc and overhangs to a side away from the wheel disc; and the blades are arranged in a circular array with the axis of the wheel disc as the array axis, and blade channels are formed between the blades; A wheel cover is used for the union of the overhanging ends of the blades and has an air inlet, wherein the axis of the air inlet and the wheel cover is colinear with the axis of the wheel disc; The wheel rim of the wheel cover is tooth-shaped, and the tooth height of the teeth included is not less than one-third of the radial dimension of the wheel cover body, and not greater than three-fifths of the radial dimension of the wheel cover body.

[0009] Optionally, the number of teeth is the same as the number of blades.

[0010] Optionally, the shape of the front tooth profile of the tooth is the same as the shape of the blade pot profile at the same radial position of the blade.

[0011] Optionally, the distance between the front tooth profile and the blade basin profile line in the circumferential direction is 0~s; Where s is the thickness of the wheel cover.

[0012] Optionally, the tooth width on the wheel cover is one third to one half of the tooth groove width.

[0013] Optionally, the bottom arc of the tooth groove is transitional, and at least the arc between the back tooth profile and the tooth top is transitional.

[0014] Optionally, the teeth are rear-curved teeth.

[0015] Optionally, a reinforcement ring is provided at the radial end of the wheel cover.

[0016] Optionally, an inlet ring is provided at the centripetal end of the wheel cover to define the air inlet and outlet.

[0017] According to a second aspect of an embodiment of the present invention, a fan is provided, comprising the serrated wheel cover impeller according to the first aspect of the embodiment of the present invention.

[0018] It is understandable that the wheel cover will inevitably reduce the overall moment of inertia of the impeller under the condition of weight reduction, thereby reducing the load on the fan main shaft and the load on the main bearing. In the embodiment of the present invention, the wheel cover used for the impeller is a serrated wheel cover, which is equivalent to reducing the weight of the wheel cover part corresponding to the tooth groove part, thereby effectively reducing the weight of the entire impeller. In terms of the combination function of the wheel cover alone, it is used to combine one end of the blades, and is generally also used to assist in constructing the blade channel to improve the overall rigidity and make the airflow flow in a predetermined direction. After research, it was found that the stress concentration position of the wheel cover is mainly distributed in the predetermined area of ​​the inlet end, that is, the centripetal part of the wheel cover, and the stress concentration on the centrifugal side is relatively weak. After testing, it was found that processing the centrifugal side of the wheel cover into a tooth shape has a relatively low impact on the service life of the impeller, but due to the weight reduction effect of the tooth shape, it can effectively reduce the load on the fan main shaft, so that the fan has a longer service life. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 Schematic diagram of the main cross-sectional structure of a serrated wheel cover impeller in one embodiment.

[0020] Figure 2 This is a schematic diagram of the left view of the sawtooth wheel cover impeller in one embodiment (partial section).

[0021] Figure 3 It is a schematic diagram of the left view of the wheel cover in one embodiment.

[0022] In the figure: 1. blades, 2. wheel cover, 3. inlet ring, 4. air inlet, 5. air cavity, 6. weld, 7. wheel disc, 8. shaft disc, 9. mounting hole.

[0023] 11. Leaf basin line, 12. Leaf back line.

[0024] 21. Tooth groove, 22. Tooth, 23. Tooth root circle, 24. Tooth top circle, 25. Dorsal tooth profile, 26. Front tooth profile. DETAILED DESCRIPTION

[0025] Based on the concept of the present invention, it can be known that in the embodiments of the present invention, emphasis is placed on the improvement of the wheel cover 2, and the remaining parts can refer to the impeller structure or construction configured using a known centrifugal fan. Therefore, the remaining parts of the impeller are only briefly described in the embodiments of the present invention.

[0026] The wheel cover 2 and parts related to the improved structure or construction of the wheel cover 2 will be described in detail below.

[0027] Figure 1 The impeller shown in the figure is an impeller equipped with a sawtooth wheel cover, and the wheel cover 2 is assembled with a group of blades, a wheel disk 7 and a shaft disk 8 as a basic structure to form an impeller.

[0028] Among them, the shaft disc 8 is the base of the impeller, and the impeller is installed on the impeller shaft through the shaft disc 8. Therefore, from the perspective of stiffness alone, the shaft disc 8 itself should have a relatively high stiffness. The shaft disc 8 in the figure is roughly a conical structure, and its purpose is also to improve the stiffness of the shaft disc 8.

[0029] The support of the shaft disc 8 to the rest of the impeller is mainly single-end support, that is, a central hole needs to be opened on the end of the impeller opposite to the end where the shaft disc 8 is located to form an air inlet 4. In other words, the air inlet 4 is often opened from the center of the impeller, and the gas introduced from the air inlet 4 enters the Figure 1 In the air chamber 5 shown in the figure, the gas is discharged through the blade channel under the action of the rotation of the impeller, and the centrifugal force generated by the rotation is applied. Therefore, this type of fan is called a centrifugal fan. It can be seen that the fan according to the embodiment of the present invention is essentially a centrifugal fan.

[0030] Since the impeller of the centrifugal fan is mainly supported at one end, in other words, the impeller is supported at one end in the centrifugal fan. Under this condition, on the one hand, there are relatively high requirements for the dynamic balance of the impeller, otherwise it is easy to produce relatively large vibrations. On the other hand, compared with the impeller supported at both ends, the centrifugal fan has higher requirements for the deadweight of the impeller. It should be understood that the heavier the impeller, the greater the bending moment of the impeller shaft, and the greater the deflection of the impeller shaft. Similarly, the heavier the impeller, the greater the load on the bearings adapted to the impeller shaft.

[0031] At the same time, the impeller shaft on which the shaft disc 8 is installed may support the impeller in a single-end support manner, that is, the impeller shaft is also installed in a cantilever manner, which has relatively high requirements on the overall weight of the impeller. In other words, impeller weight reduction has always been the most basic technical requirement in this field.

[0032] However, it should be noted that when reducing the weight of the impeller, it is necessary to ensure that the impeller has the designed rigidity. Otherwise, for example, the blade 1 may be insufficiently rigid, causing the end of the blade 1 away from the shaft disc 8 to bend and deform. If an open impeller is used, vibration will inevitably occur in the working state. It can be seen that under the condition of reducing weight, the impeller needs to ensure that it has a given designed rigidity.

[0033] Furthermore, the wheel disc 7 is generally a flat plate structure, and is generally fixed to the shaft disc 8 by a non-detachable connection method such as welding or riveting. In some implementations, a detachable connection method such as bolt connection may also be used, but it is rarely used. Since the assembly structure of the wheel disc 7 is irrelevant to the improved part of the embodiment of the present invention, it will not be described in detail here.

[0034] Under ideal conditions, the axis of the wheel disc 7 and the axis of the shaft disc 8 are collinear, and the two should maintain relatively good coaxiality. If the coaxiality is relatively poor, relatively large vibration and noise will inevitably be easily generated due to dynamic imbalance.

[0035] For other structures on the impeller, the technical requirements for coaxiality with the shaft disk 8 are relatively high, and it should be known that the coaxiality requirement is positively correlated with the operating speed of the impeller, that is, the greater the operating speed, the higher the coaxiality requirement. This is common knowledge in the field and will not be repeated here.

[0036] Regarding the blades 1, the blade group is generally formed in a circular array. Figure 2 The shape of the blade 1 and the distribution pattern of the impeller 1 on the impeller are shown by using double-dotted lines and partial sections.

[0037] exist Figure 2 The blade 1 illustrated in the structure shown is a backward curved blade. It should be known that there are three main types of blades 1 in the field of impeller technology. This is common knowledge in the field and will not be described in detail here. However, it should be known that Figure 2 The illustrated impeller structure with backward curved blades is only used to assist in explaining the concept of the present invention, and does not mean that it is only applicable to impellers with backward curved blades.

[0038] According to the characteristics of backward curved blades, it can be inferred that Figure 2 The impeller shown is in the direction of rotation Figure 2 Counterclockwise rotation in the state shown.

[0039] Furthermore, the front side of the blade 1 corresponds to Figure 2 The blade basin profile 11 shown in FIG. 1 corresponds to the rear side Figure 2 The blade back profile line 12 shown in the figure is also a common sense in the art. It is only used to illustrate that "line" is often used to represent a surface in the art. It does not cause any ambiguity. It is a standard definition in the art and will not be repeated here.

[0040] The installation method of the blade 1 is that one end of the blade 1 is fixed on the wheel disc 7 with the axial direction of the shaft disc 8 as the reference direction. The blade 1 and the wheel disc 7 are generally fixed on the wheel disc 7 by welding, but with the development of technology, there are more options, including surface connection, riveting or screw connection, etc., and related products are currently available.

[0041] For the convenience of description, the end of the blade 1 used to connect with the wheel disc 7 is called the fixed end, and the end opposite to the fixed end is called the overhanging end. It can also be seen that the blade 1 is in a state of overhanging from the fixed end to the overhanging end based on this connection method. The overhanging state is obviously easily affected by gravity and produces deflection. In the working state, under the influence of centrifugal force, the closer the blade 1 is to the overhanging end, the easier it is to bend toward the centrifugal side. Therefore, the use of a closed impeller can effectively suppress the deflection and deformation of the blade 1.

[0042] One of the necessary components of the closed impeller is the wheel cover 2. By virtue of the wheel cover 2 connecting the blades 1 at the overhanging end, the deflection and deformation of the blades 1 during operation of the impeller can be effectively suppressed. It can be seen that the wheel cover 2 itself also needs to have sufficient rigidity. Therefore, in the art, the wheel cover 2 generally adopts the following Figure 2 The conical structure shown in the example, in terms of shape alone, under the condition of the same cross-sectional area, the shear section coefficient of the conical structure itself is relatively Figure 1 The flat wheel disc 7 is larger, which is only used for comparison of shapes, and does not mean that the anti-section coefficient of the wheel cover 2 must be greater than the shear section coefficient of the wheel disc 7.

[0043] Meanwhile, the wheel cover 2 and the wheel disc 7 used in some impellers in the prior art adopt the same shape, both of which are flat plate structures. Figure 1 The illustrated structure is only used to exemplarily describe the concept of the present invention, and is not intended to be the only option.

[0044] The blades 1 of the annular array are connected at the overhanging end through the wheel cover 2 and need to leave the air inlet 4. Therefore, the wheel cover 2 is generally an annular plate or a Figure 1 The frustum-shaped cover shown in FIG. 1 needs to leave a corresponding space for the air inlet 4. Obviously, for the annular plate, its annular hole corresponds to the air inlet 4.

[0045] Based on the above-mentioned joint set, it is found through research that the stress concentration of the impeller at the wheel cover 2 mainly occurs on its centripetal side, that is, mainly on its centripetal half or small half, and the remaining part of the wheel cover 2 has a relatively small effect on the stiffness reinforcement of the impeller as a whole. Therefore, the inventor believes that the smaller here means that it still has a reinforcement effect, but considering that if its own weight is not compatible with the smaller reinforcement effect, it can be exchanged for a suitable reinforcement effect by reducing weight.

[0046] In view of this, the wheel cover 2 used in the embodiment of the present invention is a wheel cover 2 with a toothed rim, thereby removing the portion of the wheel cover 2 corresponding to the tooth groove 21, thereby effectively reducing the weight of the wheel cover 2.

[0047] At the same time, through finite element analysis, when the tooth groove 21 is opened on the centrifugal side of the wheel cover 2, the rigidity of the wheel cover 2 still meets the design requirements, and the service life is not reduced under the same load (rotation speed).

[0048] When the wheel cover 2 has a toothed rim, the amount of wheel cover cut off is about one third of the area of ​​the wheel cover 2, which can reduce the weight by about one third. The amount of wheel cover cut off should not exceed 60% of the area of ​​the wheel cover 2. Furthermore, the tooth height of the teeth 22 included in the wheel cover 2 is not less than one third of the radial dimension of the wheel cover 2 cover body, and is not greater than three fifths of the radial dimension of the wheel cover 2 cover body.

[0049] As mentioned above, the wheel cover 2 is generally a frustoconical cover, and the cover body does not include a small end hole, but is only used to represent its solid part.

[0050] In addition, as mentioned above, under ideal conditions, the axis of the wheel cover 2 is colinear with the axis of the shaft disc 8 .

[0051] exist Figure 2 In the illustrated structure, the number of teeth 22 is the same as the number of blades 1 and corresponds one to one. Figure 2 The middle blade 1 is a backward curved blade, and a portion of the line segment of the blade back profile 12 of the blade 1 in the figure is nearly coincident with the tooth 22, and in a preferred embodiment, a portion of the line segment of the blade back profile 12 coincides with the tooth 22. The portion of the line segment is a centrifugal side line segment of the blade back profile 12 shown in the figure, and the length is about 36% to 50% of the total length of the blade back profile 12.

[0052] The blade 1 is fixedly connected to the teeth 22 at the portion where the teeth 22 are located, for example, by welding.

[0053] In some implementations, the portion of the blade 1 corresponding to the tooth 22 may be extended axially, and the extended portion is overlapped on the front tooth profile 26 of the tooth 22 and then welded.

[0054] According to this structure, the connection length of the blade 1 is not shortened due to the presence of the teeth 22 .

[0055] At the same time, in order to ensure that the loss of the wheel cover 2 rigidity is reduced under the condition of the tooth groove 21, Figure 2 and Figure 3 It can be seen that the tooth 22 needs to have a certain width to ensure that the wheel cover 2 still has suitable rigidity on the centrifugal side. Therefore, the width should not be less than one-third of the tooth groove width, but should not be too large, otherwise the weight saving value will be lost.

[0056] Furthermore, the shape of the front tooth profile 25 of the tooth 22 is the same as the shape of the blade pot line 11 at the same radial position of the blade 1, so as to facilitate matching. Under this condition, the partial line segment of the blade pot line 11 of the blade 1 on the axially extended surface is coplanar with the front tooth profile 26 of the tooth 22.

[0057] Further, as an option, and as described above for welding between the blade 1 and the tooth 22, the distance between the front tooth profile 26 and the blade basin profile 11 in the circumferential direction is 0~s; where s is the thickness of the wheel cover. Different weld positions can be selected according to the positional relationship between the tooth 22 and the blade basin profile 11, and it is easy for a person skilled in the art to determine how to weld the blade 1 at the portion where the tooth 22 is located, which will not be described in detail here.

[0058] Figure 2 and Figure 3 As can be seen in the figure, the tooth 22 has a relatively gentle profile and is not prone to stress concentration. Therefore, the bottom of the tooth groove 21 has an arc transition, and at least the back tooth profile 25 and the tooth top have an arc transition.

[0059] In addition, in some embodiments, a reinforcement ring is provided at the radial end of the wheel cover 2 to connect the end of the teeth 22 at the end to improve the overall rigidity.

[0060] In addition, as an auxiliary reinforcement structure, an inlet ring 3 is also provided at the centripetal end of the wheel cover 2 to define the air inlet and outlet 3.

Claims

1. A sawtooth wheel cover impeller, characterized in that: include: Axle disc; A wheel disc, fixedly mounted on the shaft disc, wherein the axis of the wheel disc is colinear with the axis of the shaft disc; A blade group, wherein one end of a blade in the blade group is fixed to an end surface of one end of the wheel disc and overhangs to a side away from the wheel disc; and the blades are arranged in a circular array with the axis of the wheel disc as the array axis, and blade channels are formed between the blades; A wheel cover is used for the union of the overhanging ends of the blades and has an air inlet, wherein the axis of the air inlet and the wheel cover is colinear with the axis of the wheel disc; The wheel rim of the wheel cover is tooth-shaped, and the tooth height of the teeth included is not less than one-third of the radial dimension of the wheel cover body, and not greater than three-fifths of the radial dimension of the wheel cover body.

2. The sawtooth cover impeller according to claim 1, characterized in that: The number of teeth is the same as the number of blades.

3. The sawtooth cover impeller according to claim 2, characterized in that: The shape of the front tooth profile of the tooth is the same as the shape of the blade pot profile at the same radial position of the blade.

4. The sawtooth cover impeller according to claim 3, characterized in that: The distance between the front tooth profile and the blade basin profile line in the circumferential direction is 0~s; Where s is the thickness of the wheel cover.

5. The sawtooth cover impeller according to any one of claims 2 to 4, characterized in that: The tooth width on the wheel cover is one third to one half of the tooth groove width.

6. The sawtooth cover impeller according to claim 5, characterized in that: The bottom arc of the tooth groove is transitional, and at least the back tooth profile and the tooth top are transitional.

7. The sawtooth cover impeller according to claim 6, characterized in that: The teeth are backward curved.

8. The sawtooth cover impeller according to claim 1, characterized in that: A reinforcement ring is provided at the radial end of the wheel cover.

9. The sawtooth cover impeller according to claim 1, characterized in that: An inlet ring is provided at the centripetal end of the wheel cover to determine the air inlet and outlet.

10. A fan, characterized in that: It comprises the sawtooth wheel cover impeller as described in any one of claims 1 to 9.

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