Compact axial magnetic flux motor driving pump and axial force calculation method

Abstract

The invention relates to the field of pumps, in particular to a compact axial magnetic flux motor drive pump and an axial force calculation method.The pump cavity of a pump body is divided into a conveying cavity and a power cavity by a pump shell, a pump shaft is arranged in the axial direction of the pump body, and the two ends of the pump shaft are located in the conveying cavity and the power cavity correspondingly; the end, located in the conveying cavity, of the pump shaft is coaxially provided with an impeller assembly arranged corresponding to the position of the water outlet section in the conveying cavity, and the end, located in the power cavity, of the pump shaft is connected with a magnetic flux motor. A cooling flow channel is formed in the pump shaft in the axial direction in a non-penetrating mode, a jet flow channel is formed in the pump shaft in the circumferential direction of the cooling flow channel, and a cooling medium in the cooling flow channel is jetted to the impeller assembly through the jet flow channel. According to the axial magnetic flux water pump, the pump efficiency is effectively improved while the cavitation phenomenon of the impeller of the axial magnetic flux water pump is avoided.

Description

Technical Field

[0001] The present invention relates to the field of pumps, in particular to a compact axial flux motor driven pump and an axial force calculation method. Background Art

[0002] An axial flux water pump is a pump structure driven by an axial flux motor. Its core feature is that the direction of the motor's magnetic flux is parallel to the axis. Unlike traditional radial flux motors, the magnetic fields of its stator and rotor are distributed axially (parallel to the axis of rotation). The structure is flat and compact, with high power density. Its structure is as described in publication number "CN118739775A", which includes an axial flux motor mechanism and a water pump mechanism. The first stator assembly and the second stator assembly of the axial flux motor mechanism can generate a synthetic magnetic flux that passes axially through the rotor assembly, driving the rotor assembly to rotate by magnetic coupling, and then driving the power device of the water pump mechanism through the rotating shaft. During the operation of the axial flux water pump, the impact of the medium will cause the problem of insufficient flow stability. After entering the pump body, the medium directly impacts the impeller and is discharged to the pump outlet through the impeller. The impact on the impeller will increase the load on the impeller, and there is a risk of cavitation after the impeller assembly has been working for a long time. In order to avoid cavitation, the conventional measure is to increase the inlet diameter of the impeller. However, while this method reduces the risk of cavitation, it often increases hydraulic losses and reduces pump efficiency, so it needs to be solved. Summary of the Invention

[0003] To avoid and overcome the technical problems existing in the prior art, the present invention provides a compact axial flux motor driven pump and an axial force calculation method. The present invention avoids cavitation in the impeller of the axial flux water pump while effectively improving pump efficiency.

[0004] To achieve the above object, the present invention provides the following technical solutions:

[0005] A compact axial flux motor driven pump, the pump cavity of the pump body is divided into a delivery cavity and a power cavity by the pump casing, the pump shaft is arranged axially along the pump body, and its two ends are respectively located in the delivery cavity and the power cavity, the end of the pump shaft located in the delivery cavity is coaxially provided with an impeller assembly arranged corresponding to the position of the water outlet section in the delivery cavity, and the end of the pump shaft located in the power cavity is connected to the flux motor; a cooling flow channel is opened in the pump shaft in an axial non-through manner, and a jet channel is opened on the pump shaft around the cooling flow channel, and the cooling medium in the cooling flow channel is ejected toward the impeller assembly through the jet channel.

[0006] As a further solution of the present invention: the angle between the jet channel and the pump shaft is θ:

[0007]

[0008] Where k is the design coefficient;

[0009] r is the inlet radius of the impeller assembly;

[0010] n is the speed of the pump shaft;

[0011] v a is the axial velocity of the fluid in the conveying cavity.

[0012] As a further solution of the present invention:

[0013] Wherein, Q is the flow rate of the cooling channel;

[0014] N is the number of jet channels.

[0015] As a further solution of the present invention: the jet outlet of the jet channel is located between the impeller assembly and the water inlet section of the pump body.

[0016] As a further solution of the present invention: the opening end of the cooling channel is located in the power cavity, a cooling pipe is provided at the water outlet of the water outlet section, and the cooling pipe is connected to the opening end of the cooling channel after passing through the power cavity.

[0017] As a further solution of the present invention: the flux motor includes a stator assembly fixed in the power cavity, and a rotor assembly is coaxially arranged at one end of the pump shaft located in the power cavity. The rotor assembly and the stator assembly cooperate with each other through electromagnetic induction to drive the pump shaft to rotate, and the pump shaft and the pump casing are rotatably matched through a water-guided bearing.

[0018] As a further solution of the present invention: both ends of the pump body are arranged in an open manner, the openings are closed by a pump cover, the pump cover and the pump body are fastened by screws, and the contact surface is sealed by a sealing ring.

[0019] A method for calculating the axial force of a compact axial flux motor driven pump, where the total axial force acting on the pump body is F:

[0020] F=F p1 +F w1 +F d1 +F m2 (B,T)+F m3 +F d2 +F p1 (ΔP,η)+F t (α,ΔT);

[0021] Among them, F p1 Indicates the axial force due to fluid pressure;

[0022] F w1 Represents the axial force due to the weight of the rotor assembly;

[0023] F d1Indicates the axial force due to the dynamic force of the pump;

[0024] F m2 (B, T) represents the axial force generated by temperature-flux coupling;

[0025] F m3 Indicates the axial force due to mechanical force;

[0026] F d2 Indicates the axial force generated by the dynamic force of the power source;

[0027] F p1 (ΔP,η) represents the axial force generated by viscosity-fluid pressure coupling;

[0028] F t (α, ΔT) represents the additional axial force caused by the change in the gap between the rotor and the stator due to thermal expansion of the material.

[0029] As a further solution of the present invention:

[0030] B(T)=B0[1-β m (T-T0)];

[0031] β(T)=1+k T (T-T0);

[0032] Wherein, B(T) is the magnetic flux density when the flux motor is working;

[0033] T is the operating temperature of the flux motor;

[0034] A gap is the air gap area between the rotor assembly and the stator assembly;

[0035] μ0 is the magnetic permeability of vacuum;

[0036] B0 is the magnetic flux density at room temperature T0;

[0037] β m is the demagnetization temperature coefficient of the ferromagnetic flux material of the rotor assembly and the stator assembly;

[0038] β(T) is the active compensation coefficient;

[0039] k T is the gain factor adjusted by the cooling circuit.

[0040] As a further solution of the present invention: F d1 =k1·A e1 ΔP d1 ;

[0041] F d2=k2·A e2 ΔP d2 ;

[0042] Among them, k1 and k2 are dynamic force coefficients;

[0043] A e1 is the effective area of ​​the impeller;

[0044] A e2 It is the effective cross-sectional area through which the magnetic flux lines of the flux motor pass vertically;

[0045] ΔP d1 is the dynamic pressure fluctuation amplitude of the delivery cavity;

[0046] ΔP d2 is the dynamic pressure fluctuation amplitude of the power source;

[0047] F p1 (ΔP,η)=A eff ΔP (η) ;

[0048]

[0049] Among them, A eff is the effective area of ​​the impeller;

[0050] ΔP (η) is the actual pressure difference acting on the impeller after viscosity correction;

[0051] ΔP0 is the theoretical pressure difference of the conveying medium in the pump body at the design viscosity η0;

[0052] η0 is the design viscosity of the conveying medium in the pump body;

[0053] η is the actual medium viscosity of the conveying medium in the pump body;

[0054] γ is the viscosity correction factor;

[0055] F t (α, ΔT) = E·A·α·ΔT;

[0056] Where E is the elastic modulus of the material of the rotor assembly and stator assembly squeezed due to temperature changes;

[0057] A is the thermal expansion contact area of ​​the rotor assembly and the stator assembly;

[0058] α is the thermal expansion coefficient of the ferromagnetic material of the rotor assembly and stator assembly squeezed due to temperature changes;

[0059] ΔT is the temperature change of the flux motor.

[0060] Compared with the prior art, the present invention has the following beneficial effects:

[0061] 1. The present invention opens a non-through jet channel on the pump shaft. After the jet medium is introduced, under the action of the centrifugal force when the pump rotates, the jet medium drives the conveying medium to form a pre-rotation before entering the impeller, thereby reducing the direct impact loss of the medium on the impeller, reducing the impeller load, reducing the risk of cavitation, improving the stability of the medium flow process, and effectively improving the pump efficiency.

[0062] 2. The present invention obtains the diameter of the jet channel and the optimal setting angle by calculation, so that the pump efficiency can be maximized during operation; the medium at the pump outlet flows back to the cooling channel of the pump through the cooling pipe, cools the stator assembly and the rotor assembly, and can also cool the pump shaft, and finally is ejected from the jet channel, thereby improving the cavitation phenomenon of the impeller, realizing the recycling of the medium, and avoiding the risk of cavitation of the impeller.

[0063] 3. The present invention establishes a calculation formula for the axial force of the pump body and adjusts the various structural components to balance the axial forces of the entire pump, ensuring efficient and reliable operation of the unit. BRIEF DESCRIPTION OF THE DRAWINGS

[0064] Figure 1 It is a structural schematic diagram of the present invention.

[0065] In the picture:

[0066] 1. Pump body; 11. Water inlet section; 12. Water outlet section; 13. Pump cover;

[0067] 2. Conveying chamber; 3. Power chamber; 31. Rotor assembly; 32. Stator assembly;

[0068] 4. Pump shaft; 41. Cooling channel; 42. Jet channel; 43. Impeller assembly; 5. Cooling pipe. DETAILED DESCRIPTION

[0069] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0070] See also Figure 1In an embodiment of the present invention, a compact axial flux motor drives a pump and an axial force calculation method. The pump body 1 is a vertical design, and the pump cavity of the pump body 1 is divided into a delivery cavity 2 and a power cavity 3 by the pump casing. An axial flux motor is arranged in the power cavity 3 along the axial direction of the pump body 1. The axial flux motor is a single-disc structure. The stator assembly 32 and the rotor assembly 31 are both disc-shaped. When the motor is working, the rotor disk is driven to rotate by a single stator disk. There is a planar air gap between the stator assembly 32 and the rotor assembly 31. The magnetic field direction of the air gap is parallel to the direction of the motor axis. When the motor is working, the electromagnetic coil of the stator assembly 32 (electromagnetic stator) generates a magnetic flux that passes through the rotor assembly 31 (permanent magnet rotor), thereby driving the rotor assembly 31 to rotate.

[0071] The water inlet section 11 and the water outlet section 12 of the pump body 1 are both connected to the delivery chamber 2. The pump shaft 4 axially passes through the delivery chamber 2 and the power chamber 3. One end of the pump shaft 4 is integrally arranged with the rotor assembly 31. A water-guided bearing is mounted on the pump shaft 4, which rotates with the pump casing through the water-guided bearing. An impeller assembly 43 is coaxially mounted on one end of the pump shaft 4 located within the delivery chamber 2. The impeller assembly 43 is arranged correspondingly to the position of the water outlet section 12. After the end of the pump shaft 4 passes through the impeller assembly 43, it is fixed with a double nut. A bearing ring is mounted on the end of the pump shaft 4 to support the pump shaft 4.

[0072] Both ends of the pump body 1 are open, and the openings are closed by pump covers 13. The pump cover 13 is fixed to the pump body 1 by motor screws. A sealing ring is provided between the contact surface of the pump cover 13 and the pump body 1.

[0073] A cooling channel 41 is axially provided on the pump shaft 4, but does not penetrate the pump shaft 4. The open end of the cooling channel 41 is located in the power chamber 3. A cooling pipe 4 is externally connected to the tongue of the water outlet section 12 of the pump body 1. The cooling pipe 4 communicates with the cooling channel 41 after entering the power chamber 3. A plurality of jet channels 42 are provided on the pump shaft 4. The jet channels 42 are arranged at an angle to connect the cooling channel 41 and the delivery chamber 2. The jet outlet of the jet channel 42 is directed toward the impeller assembly 43. The axial spacing between the outlet of the jet channel 42 and the outlet of the water inlet section 11 is preferably maintained at 5 mm to 10 mm to allow sufficient pre-swirl of the medium flowing into the impeller.

[0074] The angle between the jet channel 42 and the pump shaft 4 is set to θ:

[0075]

[0076] Among them, k is the design coefficient, which ranges from 0.2 to 0.4;

[0077] r is the inlet radius of the impeller assembly 43;

[0078] n is the rotational speed of the pump shaft 4;

[0079] va is the axial velocity of the fluid in the delivery chamber 2;

[0080] The diameter of the jet channel 42 is d:

[0081]

[0082] Wherein, Q is the flow rate of the cooling channel 41;

[0083] N is the number of jet channels 42 .

[0084] When designing a pump, the axial force of the pump body is calculated, and the axial force balance is ensured by adjusting various design parameters.

[0085] The total axial force on the pump body 1 is F:

[0086] F=F p1 +F w1 +F d1 +F m2 (B,T)+F m3 +F d2 +F p1 (ΔP,η)+F t (α,ΔT);

[0087] Among them, F p1 Indicates the axial force due to fluid pressure;

[0088] F w1 Represents the axial force due to the weight of the rotor assembly;

[0089] F d1 Indicates the axial force due to the dynamic force of the pump;

[0090] F m2 (B, T) represents the axial force generated by temperature-flux coupling;

[0091] F m3 Indicates the axial force due to mechanical force;

[0092] F d2 Indicates the axial force generated by the dynamic force of the power source;

[0093] F p1 (ΔP,η) represents the axial force generated by viscosity-fluid pressure coupling;

[0094] F t (α, ΔT) represents the additional axial force caused by the change in the gap between the rotor and the stator due to thermal expansion of the material.

[0095]

[0096] B(T)=B0[1-β m (T-T0)];

[0097] β(T)=1+k T (T-T0);

[0098] Wherein, B(T) is the magnetic flux density when the flux motor is working;

[0099] T is the operating temperature of the flux motor;

[0100] A gap is the air gap area between the rotor assembly 31 and the stator assembly 32;

[0101] μ0 is the magnetic permeability of vacuum;

[0102] B0 is the magnetic flux density at room temperature T0;

[0103] β m is the demagnetization temperature coefficient of the ferromagnetic flux material of the rotor assembly 31 and the stator assembly 32 . In this embodiment, the material is neodymium iron boron magnet.

[0104] β(T) is the active compensation coefficient, ranging from 1.0 to 3.0;

[0105] k T is the gain factor adjusted by the cooling circuit.

[0106] F d1 =k1·A e1 ΔP d1 ;

[0107] F d2 =k2·A e2 ΔP d2 ;

[0108] Among them, k1 and k2 are dynamic force coefficients, and the value range under turbulent conditions is 0.05~0.2;

[0109] A e1 is the effective area of ​​the impeller;

[0110] A e2 It is the effective cross-sectional area through which the magnetic flux lines of the flux motor pass vertically;

[0111] ΔP d1 is the dynamic pressure fluctuation amplitude of the delivery cavity;

[0112] ΔP d2 is the dynamic pressure fluctuation amplitude of the power source;

[0113] F p1 (ΔP,η)=A eff ΔP(η) ;

[0114]

[0115] Among them, A eff is the effective area of ​​the impeller;

[0116] ΔP (η) is the actual pressure difference acting on the impeller after viscosity correction;

[0117] ΔP0 is the theoretical pressure difference of the conveying medium in the pump body at the design viscosity η0;

[0118] η0 is the design viscosity of the conveying medium in the pump body;

[0119] η is the actual medium viscosity of the conveying medium in the pump body;

[0120] γ is the viscosity correction coefficient; in this embodiment, γ=0.05, which means that for every 1% increase in viscosity, the pressure difference increases by 0.05%.

[0121] F t (α, ΔT) = E·A·α·ΔT;

[0122] Wherein, E is the elastic modulus of the material of the rotor assembly 31 and the stator assembly 32 that is squeezed due to temperature changes; the material used in this embodiment is iron, and the elastic modulus is 210 GPa.

[0123] A is the thermal expansion contact area of ​​the rotor assembly 31 and the stator assembly 32;

[0124] α is the thermal expansion coefficient of the ferromagnetic material of the rotor assembly 31 and the stator assembly 32 squeezed due to temperature changes;

[0125] ΔT is the temperature change of the flux motor.

[0126] Under the same test conditions (test medium: antifreeze, ambient temperature: 22°C, outlet pipe diameter: 46mm, atmospheric pressure 101.35Kpa), the pump of the present application and the pump without adding the jet channel were tested and compared, and the pump efficiency data are shown in Table 1 below.

[0127] Table 1

[0128]

[0129]

[0130] Under the same other conditions, it can be seen from the data in the above table that the pump efficiency of the present application is significantly higher than the conventional pump efficiency without adding a jet channel.

[0131] The basic principles of the present application have been described above in conjunction with specific embodiments. However, it should be noted that the advantages, strengths, and effects mentioned in this application are merely illustrative and not restrictive, and it should not be assumed that these advantages, strengths, and effects are required of each embodiment of this application. In addition, the specific details disclosed above are merely illustrative and facilitating understanding, and are not restrictive. The above details do not limit this application to necessarily being implemented using the above specific details.

[0132] The block diagrams of the devices, devices, equipment, and systems involved in this application are merely illustrative examples and are not intended to require or imply that they must be connected, arranged, or configured in the manner shown in the block diagrams. As will be appreciated by those skilled in the art, these devices, devices, equipment, and systems can be connected, arranged, or configured in any manner. Words such as "include," "comprise," "have," and the like are open-ended words, meaning "including but not limited to," and can be used interchangeably therewith. The words "or" and "and" used herein refer to the words "and / or" and can be used interchangeably therewith, unless the context clearly indicates otherwise. The word "such as" used herein refers to the phrase "such as but not limited to," and can be used interchangeably therewith.

Claims

1. A compact axial flux motor driven pump, characterized in that The pump chamber of the pump body (1) is divided into a delivery chamber (2) and a power chamber (3) by a pump shell. The pump shaft (4) is arranged axially along the pump body (1), and its two ends are respectively located in the delivery chamber (2) and the power chamber (3). One end of the pump shaft (4) located in the delivery chamber (2) is coaxially provided with an impeller assembly (43) arranged corresponding to the position of the water outlet section (12) in the delivery chamber (2). The end of the pump shaft (4) located in the power chamber (3) is connected to the magnetic flux motor. A cooling channel (41) is opened in the pump shaft (4) in an axial non-through manner. A jet channel (42) is opened on the pump shaft (4) in a circumferential direction around the cooling channel (41). The cooling medium in the cooling channel (41) is ejected toward the impeller assembly (43) through the jet channel (42).

2. A compact axial flux motor driven pump according to claim 1, characterized in that: The angle between the jet channel (42) and the pump shaft (4) is θ: Where k is the design coefficient; r is the inlet radius of the impeller assembly (43); n is the rotational speed of the pump shaft (4); v a is the axial velocity of the fluid in the delivery chamber (2).

3. A compact axial flux motor driven pump according to claim 1, characterized in that: The diameter of the jet channel (42) is d: Wherein, Q is the flow rate of the cooling channel (41); N is the number of jet channels (42).

4. A compact axial flux motor driven pump according to any one of claims 1 to 3, characterized in that: The jet outlet of the jet channel (42) is located between the impeller assembly (43) and the water inlet section (11) of the pump body (1).

5. A compact axial flux motor driven pump according to any one of claims 1 to 3, characterized in that: The open end of the cooling channel (41) is located in the power cavity (3), and a cooling pipe (5) is provided at the water outlet of the water outlet section (12). The cooling pipe (5) passes through the power cavity (3) and is communicated with the open end of the cooling channel (41).

6. A compact axial flux motor driven pump according to any one of claims 1 to 3, characterized in that: The magnetic flux motor comprises a stator assembly (32) fixed in a power chamber (3); a rotor assembly (31) is coaxially arranged at one end of a pump shaft (4) located in the power chamber (3); the rotor assembly (31) and the stator assembly (32) cooperate with each other through electromagnetic induction to drive the pump shaft (4) to rotate; and the pump shaft (4) and the pump casing are rotatably engaged through a water-guided bearing.

7. A compact axial flux motor driven pump and axial force calculation method according to any one of claims 1 to 3, characterized in that: Both ends of the pump body (1) are arranged in an open manner, and the openings are closed by a pump cover (13). The pump cover (13) and the pump body (1) are fastened by screws, and the contact surfaces are sealed by a sealing ring.

8. A method for calculating the axial force of a compact axial flux motor driven pump according to any one of claims 1 to 3, characterized in that: The total axial force on the pump body (1) is F: F=F p1 +F w1 +F d1 +F m2 (B,T)+F m3 +F d2 +F p1 (ΔP,η)+F t (α,ΔT); Among them, F p1 Indicates the axial force due to fluid pressure; F w1 Represents the axial force due to the weight of the rotor assembly; F d1 Indicates the axial force due to the dynamic force of the pump; F m2 (B, T) represents the axial force generated by temperature-flux coupling; F m3 Indicates the axial force due to mechanical force; F d2 Indicates the axial force generated by the dynamic force of the power source; F p1 (ΔP,η) represents the axial force generated by viscosity-fluid pressure coupling; F t (α, ΔT) represents the additional axial force caused by the change in the gap between the rotor and the stator due to thermal expansion of the material.

9. The method for calculating the axial force of a compact axial flux motor driven pump according to claim 8, characterized in that: B(T)=B0[1-β m (T-T0)]; β(T)=1+k T (T-T0); Wherein, B(T) is the magnetic flux density when the flux motor is working; T is the operating temperature of the flux motor; A gap is the air gap area between the rotor assembly (31) and the stator assembly (32); μ0 is the magnetic permeability of vacuum; B0 is the magnetic flux density at room temperature T0; β m The demagnetization temperature coefficient of the ferromagnetic flux material of the rotor assembly (31) and the stator assembly (32); β(T) is the active compensation coefficient; k T is the gain factor adjusted by the cooling circuit.

10. The method for calculating the axial force of a compact axial flux motor driven pump according to claim 1, characterized in that: F d1 =k1·A e1 ·ΔP d1 ; F d2 =k2·A e2 ·ΔP d2 ; Among them, k1 and k2 are dynamic force coefficients; A e1 is the effective area of ​​the impeller; A e2 It is the effective cross-sectional area through which the magnetic flux lines of the flux motor pass vertically; ΔP d1 is the dynamic pressure fluctuation amplitude of the delivery cavity; ΔP d2 is the dynamic pressure fluctuation amplitude of the power source; F p1 (ΔP,η)=A eff ·ΔP (η) ; Among them, A eff is the effective area of ​​the impeller; ΔP (η) is the actual pressure difference acting on the impeller after viscosity correction; ΔP0 is the theoretical pressure difference of the conveying medium in the pump body at the design viscosity η0; η0 is the design viscosity of the conveying medium in the pump body; η is the actual medium viscosity of the conveying medium in the pump body; γ is the viscosity correction factor; F t (α,ΔT)=E·A·α·ΔT; Wherein, E is the elastic modulus of the material of the rotor assembly (31) and the stator assembly (32) extruded due to temperature changes; A is the thermal expansion contact area of ​​the rotor assembly (31) and the stator assembly (32); α is the thermal expansion coefficient of the ferromagnetic material of the rotor assembly (31) and the stator assembly (32) due to temperature changes; ΔT is the temperature change of the flux motor.

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