Impeller for fluid pump and fluid pump

Abstract

The embodiments of the present disclosure relate to an impeller and a fluid pump for a fluid pump. The impeller includes: a front cover plate, which defines an impeller inlet; a rear cover plate, which includes: an axial hole for passing a pump shaft; a plurality of blades, which are evenly distributed along the circumference of the center line of the impeller, and an impeller flow channel is defined between the blades; and a plurality of reflux channels, each of which passes through the rear cover plate and corresponds to an impeller flow channel respectively, and the reflux channel is configured to allow fluid to reflux from the first surface of the rear cover plate to the second surface of the rear cover plate, and the direction in which the reflux channel extends matches the direction in which the corresponding impeller flow channel extends. The impeller and the fluid pump can make the direction of the liquid flow returning to the impeller flow channel through the reflux channel match the direction in which the impeller flow channel extends, reduce the disturbance of the main liquid flow in the impeller flow channel, and reduce the pressure difference between the front and rear cover plates.

Description

Technical Field

[0001] Embodiments of the present disclosure generally relate to the field of fluid pumps, and more particularly to an impeller for a fluid pump and a fluid pump. Background Art

[0002] The impeller of a fluid pump, such as a centrifugal pump, is usually composed of a front cover, a rear cover, and blades. Due to the large pressure difference between the front and rear covers of the impeller during operation, there is an axial force toward the inlet. In order to balance the axial force and avoid failure due to excessive bearing load, the traditional method is to drill vertical holes on the rear cover to form a balancing hole so that high-pressure water flows through the rear cover to the impeller inlet.

[0003] However, the direction of the liquid flow returning to the impeller flow channel through the balancing hole conflicts with the direction in which the impeller flow channel extends, destroying the normal flow state of the main liquid flow. It has been proven that this conflict causes a decrease in efficiency. Due to the existence of the balancing hole, internal leakage increases, and the flow state of the water in the impeller becomes more turbulent, thereby increasing the input power of the centrifugal pump and reducing the efficiency of the centrifugal pump (see: Sha Yujun, Liu Shuhong, Wu Yulin, et al. Study on the influence of balancing holes on the performance of high-temperature and high-pressure centrifugal pumps [J]. Journal of Hydroelectric Engineering, 2012, 31(06): 259-264.). It has been verified through experiments that at all flow rates, the efficiency of the impeller with balancing holes is lower than that without balancing holes. At the rated flow rate, the efficiency is reduced by an average of about 4% (see: Liu Dongsheng, Qian Jun, Huo Youwen. Experimental study on the influence of balancing holes on the performance of centrifugal pumps [J]. Equipment Machinery, 2021, (01): 10-14). Research on balance holes and reflux is particularly urgent. The traditional drilling method has great defects, and both straight drilling and oblique drilling have problems. A completely new design solution must be used to replace it. Summary of the invention

[0004] In response to the above problems, the present disclosure provides an impeller for a fluid pump and a fluid pump, which can match the direction of the liquid flow returning to the impeller flow channel through the reflux channel with the direction in which the impeller flow channel extends, reduce the disturbance to the main liquid flow in the impeller flow channel, and reduce the pressure difference between the front and rear cover plates.

[0005] According to the first aspect of the present disclosure, an impeller for a fluid pump is provided. The impeller comprises: a front cover plate, which defines an impeller inlet; a plurality of blades, which are evenly distributed along the circumference of the center line of the impeller, and an impeller flow channel is defined between adjacent blades; and a rear cover plate, which comprises: an axial hole, which is used to penetrate the pump shaft; and a plurality of return channels, each of which passes through the rear cover plate and corresponds to an impeller flow channel respectively, and the return channel is configured to allow fluid to flow back from the first surface of the rear cover plate to the second surface of the rear cover plate, and the direction in which the return channel extends matches the direction in which the corresponding impeller flow channel extends.

[0006] In some embodiments, a first distance between a geometric center point of an inlet of the return channel and a center line of the impeller is less than or equal to a second distance between a geometric center point of an outlet of the return channel and the center line of the impeller.

[0007] In some embodiments, the first distance is any value between 0.3 times and 0.4 times the diameter of the impeller inlet, and the second distance is any value between 0.3 times and 0.4 times the diameter of the impeller inlet.

[0008] In some embodiments, the reflux channel is gradually diffused from the inlet to the outlet.

[0009] In some embodiments, a diffusion angle from the inlet of the recirculation channel to the outlet of the recirculation channel is any value between 3° and 7°.

[0010] In some embodiments, the placement angle of the reflow channel is any value between 30° and 60°.

[0011] In some embodiments, the inlet of the reflow channel and the outlet of the reflow channel are elliptical.

[0012] In some embodiments, the angle between the long axis direction of the inlet of the reflow channel and the first straight line is any value between 110° and 130°, and the first straight line is a straight line passing through the geometric center point of the inlet of the reflow channel and intersecting the center line of the impeller at right angles; and the angle between the long axis direction of the outlet of the reflow channel and the second straight line is any value between 110° and 130°, and the second straight line is a straight line passing through the geometric center point of the outlet of the reflow channel and intersecting the center line of the impeller at right angles.

[0013] In some embodiments, the first surface of the rear cover plate is provided with an annular body, which is configured to cooperate with a sealing ring; the annular gap between the sealing ring and the annular body has a first cross-sectional area; the ratio of the sum of the intermediate cross-sectional areas of the multiple reflux channels to the first cross-sectional area is any value between 4 and 8.

[0014] In some embodiments, the center line of the return channel is an arc line, and the center line of the return channel is located on a cylindrical surface with the center line of the impeller as the axial direction.

[0015] In some embodiments, the geometric center point of the inlet of the reflux channel is biased to one side of the impeller rotation direction relative to the geometric center point of the outlet of the reflux channel. As the impeller rotates, the liquid near the reflux channel rotates in the opposite direction of the circumference under the action of the friction force of the rear cover plate, which will generate a circumferential speed. Compared with the balancing hole under the same conditions in the prior art, the present disclosure sets an oblique reflux channel, so that the flow angle of the reflux liquid flow is closer to the absolute speed direction, thereby improving the return capacity of the reflux channel, reducing the axial force, reducing the thrust bearing load, and improving the operating stability of the pump group.

[0016] According to a second aspect of the present disclosure, a fluid pump is provided, comprising: a guide vane body, the guide vane body defining an impeller cavity; and an impeller according to the first aspect of the present disclosure, the impeller being disposed in the impeller cavity.

[0017] In some embodiments, the guide vane body includes a guide vane body hub, which is disposed on the first surface of the rear cover plate and cooperates with the impeller; and the fluid pump further includes a sealing ring, which cooperates with the annular body disposed on the first surface of the rear cover plate; wherein a reflux cavity for fluid reflux is defined between the guide vane body hub, the sealing ring and the rear cover plate, and the reflux cavity is connected to the reflux channel. The fluid pump is a centrifugal pump.

[0018] According to the scheme disclosed in the present invention, the extension direction of the reflux channel matches the extension direction of the corresponding impeller channel, so the flow direction of the reflux liquid flow after passing through the reflux channel matches the flow direction of the main liquid flow in the impeller channel, which can significantly reduce or even avoid the adverse effects on the main liquid flow in the impeller channel. Moreover, during the rotation of the impeller, the reflux channel can also push the liquid flow forward, and the centrifugal force generated during the rotation can enable the liquid flow to obtain pressure energy, which has a function similar to that of a blade, can improve the cavitation performance and improve the hydraulic efficiency. The gradually diffused shape of the reflux channel can gradually slow down the flow rate of the liquid in the reflux channel from the inlet of the reflux channel to the outlet of the reflux channel, thereby matching the flow rate of the main liquid flow in terms of flow rate and reducing interference with the main liquid flow.

[0019] It should be understood that the content described in this section is not intended to identify the key or important features of the embodiments of the present disclosure, nor is it intended to limit the scope of the present disclosure. Other features of the present disclosure will become easily understood through the following description.

[0020] The embodiments of the present disclosure solve the difficulties and pain points of the balancing hole of the prior art and have a variety of excellent functions. In addition to balancing the axial force, there are also pressure energy recovery, energy conversion, improved cavitation performance and improved hydraulic efficiency. There are significant innovations. The innovative design solution was applied to the impeller of a multi-stage centrifugal pump, assembled into a product and tested to achieve good results. The bearing temperature rise is reduced, the axial force is reduced, the motor current is reduced, the pump efficiency is improved, and the operation is smooth, achieving good application results. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The above and other features, advantages and other aspects of the embodiments of the present disclosure will become more apparent with reference to the following detailed description in conjunction with the accompanying drawings. In the accompanying drawings, the same or similar reference numerals represent the same or similar elements.

[0022] Figure 1 A cross-sectional view of an impeller is shown.

[0023] Figure 2 A front view of an impeller is shown.

[0024] Figure 3 A cross-sectional view of an impeller for a fluid pump according to an embodiment of the present disclosure is shown.

[0025] Figure 4 A front view of an impeller for a fluid pump according to an embodiment of the present disclosure is shown.

[0026] Figure 5 A partial front view of an impeller for a fluid pump according to an embodiment of the present disclosure is shown (the front cover is omitted and not shown).

[0027] Figure 6 A schematic diagram of a return channel for a fluid pump according to an embodiment of the present disclosure is shown.

[0028] Figure 7 A cross-sectional schematic diagram of a return channel for a fluid pump according to an embodiment of the present disclosure is shown.

[0029] Figure 8 A schematic diagram showing a portion of an impeller for a fluid pump according to an embodiment of the present disclosure is shown.

[0030] Fig. 9 A partial cross-sectional view of a fluid pump according to an embodiment of the present disclosure is shown.

[0031] Fig.10 A cross-sectional view showing an impeller and a seal ring of a fluid pump according to an embodiment of the present disclosure. DETAILED DESCRIPTION

[0032] The following is a description of exemplary embodiments of the present disclosure in conjunction with the accompanying drawings, including various details of the embodiments of the present disclosure to facilitate understanding, which should be considered as merely exemplary. Therefore, it should be recognized by those of ordinary skill in the art that various changes and modifications may be made to the embodiments described herein without departing from the scope and spirit of the present disclosure. Similarly, for the sake of clarity and conciseness, descriptions of well-known functions and structures are omitted in the following description.

[0033] As used herein, the term "including" and its variations mean open inclusion, i.e., "including but not limited to". Unless otherwise stated, the term "or" means "and / or". The term "based on" means "based at least in part on". The terms "an example embodiment" and "an embodiment" mean "at least one example embodiment". The term "another embodiment" means "at least one additional embodiment". The terms "first", "second", etc. may refer to different or the same objects. Other explicit and implicit definitions may also be included below.

[0034] As described above, the setting method of the balancing hole in the traditional impeller will cause the direction of the liquid flow returning to the impeller channel through the balancing hole to conflict with the direction in which the impeller channel extends, resulting in the direction of the liquid flow returning to the impeller channel through the balancing hole conflicting with the direction of the main liquid flow in the impeller channel, thereby destroying the normal flow state of the main liquid flow.

[0035] Figure 1 FIG. 1 is a cross-sectional view of an impeller 100. For ease of explanation, arrows are used in the figure to indicate the direction of liquid flow. Figure 2 1 shows a front view of an impeller 100. For ease of description, Figure 2 The cross-sectional view of the balancing hole 114 is also shown in the figure. The impeller 100 includes, for example, a front cover plate 102, a rear cover plate 104, and a plurality of blades 110. The front cover plate 102 defines an impeller inlet 106. The rear cover plate 104 includes an axial hole 108 and a plurality of balancing holes 114. The axial hole 108 is used to pass the pump shaft. An impeller flow channel 112 is defined between the blades 110. One end of the impeller flow channel 112 is connected to the impeller inlet 106, and the other end of the impeller flow channel 112 serves as an impeller outlet 116.

[0036] It should be understood that during the operation of the fluid pump, after the liquid enters the impeller 100 through the impeller inlet 106, a high-pressure water flow is formed under the action of centrifugal force, and the high-pressure water flow flows out from the impeller outlet 116 through the impeller flow channel 112. Since the pressure difference between the front cover plate 102 and the rear cover plate 104 of the impeller 100 is large during operation, there is an axial force toward the impeller inlet 106. In order to balance the axial force and avoid failure due to excessive bearing load, for example, a vertical hole can be drilled on the rear cover plate 104 to form a balancing hole 114, so that the high-pressure water flow passes through the rear cover plate 104 through the balancing hole 114 and flows to the impeller inlet 106.

[0037] It is worth noting that the balancing hole 114 penetrates the rear cover plate 104, so that the first surface of the rear cover plate 104 (e.g., the back surface, i.e., the surface away from the impeller inlet 106) is connected to the second surface of the rear cover plate 104 (e.g., the front surface, i.e., the surface close to the impeller inlet 106). The inlet 1141 of the balancing hole 114 is arranged on the first surface of the rear cover plate 104, and the outlet 1142 of the balancing hole 114 is arranged on the second surface of the rear cover plate 104. The balancing hole 114 is arranged parallel to the center line of the impeller. It should be understood that the center line of the impeller is the central axis of the impeller. When the impeller is mounted on the pump shaft, the center line of the impeller coincides with the center line of the pump shaft. After the high-pressure water flows out through the impeller outlet 116, a part of the high-pressure water flows through the first surface of the rear cover plate 104, and then flows back to the second surface of the rear cover plate 104 through the balancing hole 114, thereby merging with the main liquid flow in the impeller flow channel 112. It should be noted that since the balancing hole 114 is arranged parallel to the center line of the impeller, there is an impact between the flow direction of the return liquid flow after passing through the balancing hole 114 and the flow direction of the main liquid flow in the impeller channel 112. Therefore, the return liquid flow destroys the normal flow state of the main liquid flow in the impeller channel 112.

[0038] In order to at least partially solve one or more of the above problems and other potential problems, the exemplary embodiments of the present disclosure propose an impeller for a fluid pump and a fluid pump. According to the scheme of the present disclosure, the extension direction of the reflux channel matches the extension direction of the impeller flow channel to which it corresponds, so that the flow direction of the reflux liquid flow after passing through the reflux channel matches the flow direction of the main liquid flow in the impeller flow channel, which can significantly reduce or even avoid the adverse effects on the main liquid flow in the impeller flow channel. Moreover, during the rotation of the impeller, the reflux channel can also push the liquid flow forward, and the centrifugal force generated during the rotation can enable the liquid flow to obtain pressure energy, which has a function similar to that of a blade, can improve the cavitation performance and improve the hydraulic efficiency. The gradually diffused shape of the reflux channel can make the flow rate of the liquid in the reflux channel gradually slow down from the inlet of the reflux channel to the outlet of the reflux channel, so as to match the flow rate of the main liquid flow in terms of flow rate and reduce interference with the main liquid flow.

[0039] Figure 3 A cross-sectional view of an impeller 200 for a fluid pump according to an embodiment of the present disclosure is shown. Figure 4 A front view of an impeller 200 for a fluid pump according to an embodiment of the present disclosure is shown. Figure 5 FIG. 2 is a partial front view of an impeller 200 for a fluid pump according to an embodiment of the present disclosure, wherein the front cover plate 202 is omitted for ease of illustration. Figure 6 A schematic diagram of a return channel 214 for a fluid pump according to an embodiment of the present disclosure is shown. For ease of illustration, the return channel 214 is shown in dotted lines. Figure 7 A cross-sectional schematic diagram of a return channel 214 for a fluid pump according to an embodiment of the present disclosure is shown. Figure 8A schematic diagram of a portion of an impeller 200 for a fluid pump according to an embodiment of the present disclosure is shown.

[0040] The impeller 200 includes, for example, a front cover plate 202, a rear cover plate 204, and a plurality of blades 210. The front cover plate 202 defines an impeller inlet 206. The rear cover plate 204 includes an axial hole 208 and a plurality of return channels 214. An impeller flow channel 212 is defined between two adjacent blades 210. One end of the impeller flow channel 212 is communicated with the impeller inlet 206, and the other end of the impeller flow channel 212 serves as an impeller outlet 216.

[0041] Each of the multiple reflux channels 214 passes through the rear cover plate 204 and corresponds to an impeller channel 212 respectively. The reflux channel 214 is configured to allow the fluid to reflux from the first surface of the rear cover plate 204 to the second surface of the rear cover plate 204. The direction in which the reflux channel 214 extends matches the direction in which the corresponding impeller channel 212 extends, so that the direction in which the liquid in the reflux channel 214 refluxes matches the direction in which the corresponding impeller channel 212 extends, thereby matching the direction in which the liquid in the reflux channel 214 refluxes matches the direction in which the main liquid flow in the corresponding impeller channel 212 extends. The direction in which the reflux channel 214 extends may be a macro extension trend reflected by the overall shape and posture of the reflux channel 214. The direction in which the impeller channel 212 extends may be a macro extension trend reflected by the overall shape and posture of the impeller channel 212. The return channel 214 obliquely penetrates the rear cover plate 204, that is, the direction in which the return channel 214 extends is inclined relative to the center line of the impeller, and the direction in which the return channel 214 extends is not parallel to the center line of the impeller. The direction in which the return channel 214 extends is, for example, characterized by a straight line passing through the geometric center point P1 of the inlet 2141 of the return channel 214 and the geometric center point P2 of the outlet 2142 of the return channel 214. The direction in which the impeller channel 212 extends is, for example, characterized by the tangent direction of the impeller channel 212 at the geometric center point P2 of the outlet 2142 of the return channel 214. It should be understood that the impeller channel 212 presents a curved shape defined by the blades 210. The tangent direction of the impeller channel 212 at the geometric center point P2 of the outlet 2142 of the return channel 214, i.e., the direction passing through the geometric center point P2 of the outlet 2142 of the return channel 214 and being tangent to the impeller channel 212, can reflect the direction of the main liquid flow in the impeller channel 212 at the outlet 2142 of the return channel 214. For example, the angle between the direction in which the return channel 214 extends and the direction in which the corresponding impeller channel 212 extends is less than or equal to a predetermined angle, so that the angle between the direction in which the liquid in the return channel 214 refluxes and the direction in which the corresponding impeller channel 212 extends is less than or equal to a predetermined angle, so that the direction in which the liquid in the return channel 214 refluxes matches the direction in which the corresponding impeller channel 212 extends, thereby matching the direction in which the liquid in the return channel 214 refluxes with the direction in which the main liquid flow in the corresponding impeller channel 212 is matched. It should be understood that the direction of liquid reflux in the reflux channel 214 is defined by the reflux channel 214, and the direction of the main liquid flow in the impeller channel 212 is related to the shape of the impeller channel 212. The predetermined angle is an acute angle. In some embodiments, the predetermined angle is, for example, 45°. In some embodiments, the predetermined angle is, for example, 30°. The first surface of the rear cover plate 204 is, for example, the back surface of the rear cover plate 204, that is, the surface away from the impeller inlet 206; the second surface of the rear cover plate 204 is, for example, the front surface of the rear cover plate 204, that is, the surface close to the impeller inlet 206, which can also be called the working surface of the rear cover plate 204.It should be understood that the inlet 2141 of the return channel 214 is disposed on the first surface of the rear cover plate 204 , and the outlet 2142 of the return channel 214 is disposed on the second surface of the rear cover plate 204 .

[0042] In some embodiments, the geometric center point P1 of the inlet 2141 of the reflux channel 214 is biased toward one side of the impeller rotation direction relative to the geometric center point P2 of the outlet 2142 of the reflux channel 214. As the impeller rotates, the liquid near the reflux channel 214 will generate a circumferential speed in the opposite direction of the circumferential rotation under the action of the friction force of the rear cover plate. Compared with the balancing hole of the same conditions in the prior art, the embodiment of the present disclosure sets an oblique reflux channel 214, so that the flow angle of the reflux liquid flow is closer to the absolute velocity direction, thereby improving the return capacity of the reflux channel 214, reducing the axial force, reducing the thrust bearing load, and improving the operating stability of the pump group.

[0043] In some embodiments, a first distance R1 between a geometric center point P1 of an inlet 2141 of the return channel 214 and a center line A of the impeller is less than or equal to a second distance R2 between a geometric center point P2 of an outlet 2142 of the return channel 214 and a center line A of the impeller. In some embodiments, a first distance R1 between a geometric center point P1 of an inlet 2141 of the return channel 214 and a center line A of the impeller is equal to a second distance R2 between a geometric center point P2 of an outlet 2142 of the return channel 214 and a center line A of the impeller.

[0044] In some embodiments, the first distance R1 is any value between 0.3 and 0.4 times the diameter D1 of the impeller inlet 206, and the second distance R2 is any value between 0.3 and 0.4 times the diameter D1 of the impeller inlet 206. That is, R1=(0.3-0.4)D1, R2=(0.3-0.4)D1. In some embodiments, R2>R1.

[0045] In some embodiments, the inlet 2141 of the reflux channel 214 to the outlet 2142 of the reflux channel 214 is gradually diffused. That is, the size (or cross-sectional area) of the reflux channel 214 gradually increases from the inlet 2141 of the reflux channel 214 to the outlet 2142 of the reflux channel 214. The diffusion angle θ1 from the inlet 2141 of the reflux channel 214 to the outlet 2142 of the reflux channel 214 is any value between 3° and 7°. The gradually diffused shape of the reflux channel 214 can gradually slow down the flow rate of the liquid in the reflux channel 214 from the inlet 2141 of the reflux channel 214 to the outlet 2142 of the reflux channel 214, thereby matching the flow rate of the main liquid flow in terms of flow rate and reducing interference with the main liquid flow.

[0046] It is worth noting that the placement angle θ2 of the return channel 214 is any value between 30° and 60°.

[0047] In some embodiments, the center line of the return channel 214 is a straight line. For example, the return channel 214 can be formed by punching holes along a straight line, and the main part of the return channel 214 is in a truncated cone shape. The placement angle θ2 of the return channel 214 is the angle between the center line of the return channel 214 and the plane where the first surface of the rear cover plate 204 is located.

[0048] In some embodiments, the center line of the return channel 214 is an arc. For example, the impeller 200 can be manufactured using a 3D printing process to form a return channel 214 with an arc center line. The center line of the return channel 214 is located on a cylindrical surface with the center line A of the impeller as the axial direction. The placement angle θ2 of the return channel 214 is the rise angle of the cylindrical surface where the center line of the return channel 214 is located after the cylindrical surface is unfolded.

[0049] In some embodiments, the inlet 2141 of the reflow channel 214 and the outlet 2142 of the reflow channel 214 are elliptical. In some embodiments, the angle between the long axis direction of the inlet 2141 of the reflow channel 214 and the first straight line is any value between 110° and 130°. The first straight line is a straight line that passes through the geometric center point of the inlet of the reflow channel and intersects perpendicularly with the center line A of the impeller. The angle β between the long axis direction of the outlet 2142 of the reflow channel 214 (for example, the straight line L3 is the straight line where the long axis of the outlet 2142 of the reflow channel 214 is located) and the second straight line L1 is any value between 110° and 130°. The second straight line L1 is a straight line that passes through the geometric center point P2 of the outlet 2142 of the reflow channel 214 and intersects perpendicularly with the center line A of the impeller. For ease of explanation, the straight line L2 in the figure is a straight line passing through the geometric center point P2 of the outlet 2142 of the reflow channel 214 and is perpendicular to the second straight line L1, and the angle α is any value between 20° and 40°.

[0050] It is worth noting that, due to the rotation of the impeller 200, the liquid flow passing through the reflow channel 214 can obtain pressure energy under the action of the centrifugal force generated during the rotation. In addition, the flow direction is basically consistent with the flow direction of the main liquid flow, which is very beneficial to improving the cavitation performance.

[0051] Fig. 9 A partial cross-sectional view of a fluid pump 300 according to an embodiment of the present disclosure is shown. Fig.10 A cross-sectional view of an impeller and a sealing ring of a fluid pump 300 according to an embodiment of the present disclosure is shown. The fluid pump 300 includes a guide vane body 310, a pump shaft 306, a sleeve 308, and an impeller 200. The guide vane body 310 defines an impeller cavity, and the guide vane body 310 includes, for example, a guide vane body hub 302. The impeller 200 is disposed in the impeller cavity.

[0052] It should be understood that the guide vane body hub 302 is arranged on the first surface of the rear cover plate 204 and cooperates with the impeller 200. The guide vane body 310 is provided with a guide vane 303. The fluid pump 300 also includes a sealing ring 304, which cooperates with an annular body 305 arranged on the first surface of the rear cover plate. A reflux cavity for fluid reflux is defined between the guide vane body hub 302, the sealing ring 304 and the rear cover plate 204, and the reflux cavity is connected to the reflux channel 214. The fluid pump 300 is, for example, a centrifugal pump.

[0053] It is worth noting that the first surface of the rear cover plate 204 is provided with an annular body 305, which is configured to cooperate with the sealing ring 304; the annular gap between the sealing ring 304 and the annular body 305 has a first cross-sectional area. The ratio of the sum of the middle cross-sectional areas of the plurality of reflux channels 214 to the first cross-sectional area is any value between 4 and 8.

[0054] The diameter of the flow channel corresponding to the inlet 2141 of the reflux channel 214 is d1. It is worth noting that the cross-section perpendicular to the center line of the reflux channel 214 at the inlet 2141 of the reflux channel 214 is circular, and the diameter of the cross-section is d1. The diameter of the flow channel corresponding to the outlet 2142 of the reflux channel 214 is d2. It is worth noting that the cross-section perpendicular to the center line of the reflux channel 214 at the outlet 2142 of the reflux channel 214 is circular, and the diameter of the cross-section is d2. It should be understood that there is a gradual diffusion from the inlet 2141 of the reflux channel 214 to the outlet 2142 of the reflux channel 214, therefore, d2> d1. The middle cross-sectional area of ​​a single reflux channel 214 is (d1 2 +d2 2 )π / 8. The middle cross-sectional area of ​​the return channel 214 is the area of ​​the cross section perpendicular to the center line of the return channel 214 at the midpoint of the return channel 214 along the center line direction, and the cross section is circular. The number of return channels 214 is z, and the sum of the middle cross-sectional areas of the plurality of return channels 214 is z(d1 2 +d2 2 )π / 8. z is, for example, any value between 5 and 9.

[0055] The sealing ring gap area, that is, the first cross-sectional area of ​​the annular gap between the sealing ring 304 and the annular body 305 is (D3 2 -D2 2)π / 4, wherein D3 is the inner diameter of the sealing ring 304, and D2 is the outer diameter of the annular body 305. It should be understood that the cross section of the gap between the sealing ring 304 and the annular body 305 is annular. The ratio of the sum of the intermediate cross-sectional areas of the plurality of reflux channels to the first cross-sectional area is any value between 4 and 8. That is, the sum of the intermediate cross-sectional areas of the plurality of reflux channels is 4 to 8 times the area of ​​the sealing ring gap. This allows the fluid pump 300 to obtain good balance performance and hydraulic performance.

[0056] It is worth noting that, based on the fluid pump 300, a small amount of return water flows from the impeller outlet 216, through the gap between the guide vane hub 302, the sealing ring 304 and the impeller 200, and then through the multiple return channels 214 on the rear cover plate 204, and flows to the impeller inlet 206. Since the return channel 214 obliquely passes through the rear cover plate 204, the water flow direction is relatively close to the direction in which the impeller flow channel 212 extends, and therefore, the water flow direction is relatively close to the main liquid flow direction entering the impeller blades 210, and the hydraulic performance is taken into account while balancing the axial force.

[0057] The embodiments of the present disclosure have been described above, and the above description is exemplary, not exhaustive, and is not limited to the disclosed embodiments. Many modifications and changes will be apparent to those of ordinary skill in the art without departing from the scope and spirit of the described embodiments. The selection of terms used herein is intended to best explain the principles of the embodiments, practical applications, or technical improvements in the market, or to enable other persons of ordinary skill in the art to understand the embodiments disclosed herein.

[0058] The above are only optional embodiments of the present disclosure and are not intended to limit the present disclosure. For those skilled in the art, the present disclosure may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present disclosure shall be included in the protection scope of the present disclosure.

Claims

1. An impeller for a fluid pump, characterized in that: include: A front cover plate, the front cover plate defines an impeller inlet; A plurality of blades, wherein the plurality of blades are evenly distributed along the circumference of the center line of the impeller, and an impeller flow channel is defined between adjacent blades; as well as Rear cover, including: A shaft hole for passing a pump shaft; and A plurality of return channels, each of which obliquely penetrates the rear cover plate and corresponds to an impeller flow channel respectively, the return channel being configured to allow fluid to return from the first surface of the rear cover plate to the second surface of the rear cover plate, the angle between the direction in which the return channel extends and the direction in which the corresponding impeller flow channel extends is less than or equal to 45°, so that the direction in which the return channel extends matches the direction in which the corresponding impeller flow channel extends, the direction in which the return channel extends is characterized by a straight line passing through a geometric center point of an inlet of the return channel and a geometric center point of an outlet of the return channel; the direction in which the impeller flow channel extends is characterized by a tangent direction of the impeller flow channel at a geometric center point of an outlet of the return channel; the geometric center point of the inlet of the return channel is biased toward one side of the impeller rotation direction relative to the geometric center point of the outlet of the return channel; The reflux channel is gradually diffused from its inlet to its outlet; the placement angle of the reflux channel is any value between 30° and 60°.

2. The impeller according to claim 1, characterized in that: A first distance between a geometric center point of an inlet of the return channel and a center line of the impeller is less than or equal to a second distance between a geometric center point of an outlet of the return channel and a center line of the impeller.

3. The impeller according to claim 2, characterized in that: The first distance is any value between 0.3 times and 0.4 times the diameter of the impeller inlet, and the second distance is any value between 0.3 times and 0.4 times the diameter of the impeller inlet.

4. The impeller according to claim 1, characterized in that: The diffusion angle from the inlet of the recirculation channel to the outlet of the recirculation channel is any value between 3° and 7°.

5. The impeller according to claim 1, characterized in that The inlet of the reflux channel and the outlet of the reflux channel are elliptical.

6. The impeller according to claim 5, characterized in that The angle between the long axis direction of the inlet of the reflux channel and the first straight line is any value between 110° and 130°, and the first straight line is a straight line passing through the geometric center point of the inlet of the reflux channel and perpendicularly intersecting the center line of the impeller; as well as The angle between the long axis direction of the outlet of the reflow channel and the second straight line is any value between 110° and 130°, and the second straight line is a straight line passing through the geometric center point of the outlet of the reflow channel and perpendicularly intersecting the center line of the impeller.

7. The impeller according to claim 1, characterized in that The first surface of the rear cover plate is provided with an annular body, which is configured to cooperate with the sealing ring; the annular gap between the sealing ring and the annular body has a first cross-sectional area; the ratio of the sum of the intermediate cross-sectional areas of multiple reflux channels to the first cross-sectional area is any value between 4 and 8.

8. The impeller according to claim 1, characterized in that The center line of the return channel is an arc line, and the center line of the return channel is located on a cylindrical surface with the center line of the impeller as the axial direction.

9. A fluid pump, characterized in that: include: The guide vane body defines the impeller cavity; as well as The impeller according to any one of claims 1 to 8 is arranged in the impeller chamber.

10. The fluid pump according to claim 9, characterized in that The guide vane body comprises a guide vane body hub, which is arranged on the first surface of the rear cover plate and matches with the impeller; and The fluid pump further includes a sealing ring, which cooperates with an annular body disposed on the first surface of the rear cover plate; A reflux cavity for fluid reflux is defined between the guide vane body hub, the sealing ring and the rear cover plate, and the reflux cavity is communicated with the reflux channel.

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