Centrifugal pump with optimised vanes

Abstract

The invention relates to a centrifugal pump comprising a rotor (110) with an axis (A) of rotation and vanes (112) distributed on a face of the rotor (110), the vanes extending from a central zone (C1) of the rotor to a peripheral zone (C2) of the rotor, wherein each vane (112) has a chord (K) that extends between a vane root forming an inlet point (E) located in the central zone (C1) of the rotor and a vane tip forming an outlet point (S) located in the peripheral zone (C2) of the rotor. The inlet point (E) and the outlet point (S) form, with the centre (O) of the rotor, a deployment angle (φ) of between 75° and 110°, preferably greater than 90°, and even more preferably greater than 95°, and more precisely equal to approximately 102°.

Description

TITLE: CENTRIFUGAL PUMP WITH OPTIMIZED BLADES Technical field of the invention

[0001] The present invention relates to a centrifugal pump.

[0002] The invention finds particular application in the automotive field, notably for electric vehicles. Technological background

[0003] In electric vehicles, the number of components in the cooling circuits is increasing, which means that there is a greater loss of hydraulic pressure to compensate for than with a thermal engine.

[0004] Furthermore, in electric vehicles, a specific electric motor is provided for driving the hydraulic pump used to circulate the fluid in the cooling circuit, whereas, in thermal engines, the cooling circuit pumps are driven using a belt linked to the output shaft of the thermal engine and the energy taken from the belt to operate the pump is often seen as negligible.

[0005] In electric motors, there is therefore a need to optimize the hydraulic efficiency of these electric pumps in order to save energy taken from the vehicle's batteries, in an environment where the power of the pumps must also be higher. In this context, the applicant has established that there is an advantageous operating point for such optimization, in relation to a given value of flow rate and pressure of the pump.

[0006] As is known, a centrifugal hydraulic pump comprises a volute and a rotor comprising a plurality of blades.

[0007] It is also known to size an electric pump according to numerous geometric parameters of these elements.

[0008] To optimize the hydraulic efficiency of the electric pump at the identified operating point, the inventors noted that a particularly relevant dimensioning parameter of the electric pump is the angular extent of its blades. Summary of the invention

[0009] A centrifugal pump is therefore proposed comprising: a rotor with an axis of rotation; and one or more blades distributed on one face of the rotor, the blade(s) extending from a central zone of the rotor to a peripheral zone of the rotor; the blade(s) having a chord extending between a blade root forming an entry point located in the central zone of the rotor, and a blade nose forming an exit point located in the peripheral zone of the rotor, the entry point and the exit point forming with the axis of rotation of the rotor, in a plane orthogonal to said axis, a deployment angle of between 75° and 110°, preferably greater than 90°, or even greater than 95°, more precisely equal to approximately 102°.

[0010] Surprisingly, such a deployment angle advantageously allows the hydraulic efficiency of the electric pump to be optimized for an operating point covering wide needs.

[0011] The invention may further comprise one or more of the following optional features, in any technically possible combination.

[0012] Each blade is configured so that it has an inlet flow angle of between 16° and 22°, preferably equal to 19°, the inlet flow angle being formed between a tangent to the central zone and a tangent to the chord of the blade concerned at the inlet point.

[0013] Each blade is configured so that it has an exit flow angle of between 19° and 25°, preferably equal to 22°, the exit flow angle being formed between a tangent to the periphery of the rotor and a tangent to the chord of the blade concerned at the exit point.

[0014] The rotor has an internal radius, defining the central area of ​​the rotor, between 9 mm and 11 mm, preferably equal to 10 mm.

[0015] The rotor has an external radius, defining the peripheral area of ​​the rotor, between 22 mm and 25 mm, preferably equal to 23.2 mm.

[0016] Each blade has a decreasing wetted height between the entry point and the exit point of the blade.

[0017] Each blade has a wetted height at the inlet point of between 3.6 and 3.8 mm, preferably 3.7 mm.

[0018] Each blade has a wetted height at the exit point of between 2.3 and 2.5 mm, preferably equal to 2.4 mm.

[0019] The chord of each blade extends according to a profile defined by a polynomial of order 4 at least, in an orthonormal reference frame included in a plane orthogonal to said axis of rotation of the rotor and centered on said axis of the rotor, the abscissa axis of the reference frame passing through the nose and the ordinate axis of the reference frame passing through the root of the blade concerned.

[0020] The polynomial is defined by the following equation: y = -4. 10 -5 . % 4 + 1.1. 10 -3 . % 3 - 4.45. 10 -2 % 2 - 0.4861. x + 10.806, where x and y denote the two-dimensional coordinates in the orthonormal frame, such that x is between -3 and 24 mm.

[0021] The pump has a number of blades between 5 and 10, preferably equal to 8.

[0022] Each blade has a thickness between 0.8 and 2 mm, preferably equal to 1 mm. Brief description of the figures

[0023] The invention will be better understood with the aid of the following description, given solely by way of example and with reference to the appended drawings in which: Figure 1 illustrates a centrifugal pump according to a particular embodiment of the invention according to a top view 1a and a perspective view 1b from a diametrical section plane; Figure 2 illustrates a subassembly of the centrifugal pump according to Figure 1 according to a side view 2a showing the assembly of a rotor and a flange of said pump, a top view 2b of the rotor and a bottom view 2c of the flange; Figure 3 is a top view of a part of the rotor of the pump according to the invention; Figure 4 corresponds to Figure 3 on which is superimposed an example of a 4th order polynomial along a blade; Figure 5 is a three-dimensional exploded view of the subassembly of Figure 2; Figures 6 and 7 illustrate performance results of the centrifugal pump according to the invention. Detailed description of the invention

[0024] A centrifugal pump according to a particular embodiment of the invention will now be described with reference to Figure 1.

[0025] The centrifugal pump 100 comprises a rotor 110, a fluid inlet flange 120 configured to face the rotor, and an outlet volute 140. The volute has a cross section increasing angularly up to an outlet conduit 150 of said pump.

[0026] Preferably, the rotor 110 is disc-shaped comprising a passage hole for a drive shaft (not shown).

[0027] Preferably, the flange 120 is annular in shape with a central flare. The flange 120 comprises a fluid passage orifice 124 located in a central zone of the flange 120 and intended to receive an inlet conduit 130 of said pump 100.

[0028] The flange 120 here has a fluid introduction channel connected to a flat zone 125 of the flange by a curved zone 126. The introduction channel is located in the center in the axial continuity of the inlet conduit 130 and the flat zone 125 is located on the periphery.

[0029] The rotor 110 and the flange 120 will now be described in more detail with reference to FIG. 2.

[0030] The rotor 110 has an axis of rotation A corresponding in a plane orthogonal to said axis to a center of rotation O, around which the rotor is intended to be driven by the drive shaft.

[0031] As illustrated in view 2b, the rotor 110 comprises a plurality of blades 112 distributed on one face of the rotor. The rotor 110 and the flange 120 thus define a plurality of passages for the fluid between two neighboring blades.

[0032] Preferably, the number of blades is 8. More generally, this number is between 5 and 10.

[0033] For example, the blades 112 are distributed uniformly, that is to say regularly distributed, angularly, around the axis of rotation of the pump.

[0034] Each blade 112 extends from a central zone C1 of the rotor 110 to a peripheral zone C2 of the rotor, more particularly, to a peripheral edge C2 of the rotor 110.

[0035] A diameter of the introduction channel of the flange 120 described in FIG. 1 b is less than a diameter of the central zone C1 of the rotor 110. An external diameter of the curved zone 126 according to FIG. 1 b is greater than the diameter of the central zone C1. The central part of the rotor 110 is thus located opposite the curved part 126 of the flange 120.

[0036] The flange 120 shown in view 2c has grooves 122 configured to accommodate a longitudinal edge of the blades 112 when the flange 120 is mounted on the rotor 110 as illustrated on the left in view 2a.

[0037] The configuration of the blades 112 will now be described in more detail with reference to Figure 3.

[0038] The rotor 110 has an inner radius R1 defined relative to the center of rotation O of the rotor 110. Thus, the central zone C1 of the rotor is defined by an inner circle centered on the center of rotation O and with a radius equal to the inner radius R1. Preferably, the inner radius R1 is equal to 10 mm. More generally, this radius R1 is between 9 mm and 11 mm.

[0039] The rotor 110 is provided with an outer edge having an outer radius R2 defined relative to the center of rotation O of the rotor 110. Thus, the peripheral zone C2 of the rotor is defined by an outer circle centered on the center of rotation O and with a radius equal to the outer radius R2. Preferably, the outer radius R2 is equal to 23.2 mm. More generally, this radius R2 is between 22 mm and 25 mm.

[0040] Preferably, each blade 112 has a thickness t equal to 1 mm. More generally, the thickness t is between 0.8 and 2 mm.

[0041] Each blade 112 has a chord K extending between a blade root forming an entry point E located in the central zone C1 of the rotor and a blade nose forming an exit point S, located in the peripheral zone C2 of the rotor.

[0042] For example, for each blade 112, the entry point E corresponds to the intersection between the chord K and the inner surface of the rotor defined by the inner radius R1. For example, the exit point S corresponds to the intersection between the chord K and the outer surface of the rotor defined by the outer radius R2.

[0043] By definition, the chord of a blade refers to a curve following the profile of the blade from the blade root to the blade tip, so that each point on the curve is equidistant from the walls of the blade.

[0044] The blades have a curved profile between their blade root and their blade nose.

[0045] According to a feature of the invention, the entry point E and the exit point S form, with the center O of the rotor, a deployment angle (p) of between 75° and 110°, preferably greater than 90°, or even greater than 95°. In the present example, the deployment angle (p) is equal to approximately 102°.

[0046] For each blade 112, an inlet flow angle pi is defined at the blade root, formed between the tangent T1' to the internal circle C1 of internal radius R1 of the rotor 110 and the tangent T1 to the chord K of the blade concerned at the inlet point E.

[0047] Preferably, the inlet flow angle pi is equal to approximately 19°. More generally, this angle pi is between 16° and 22°.

[0048] For each blade 112, an outlet flow angle p2 is defined at the blade tip, formed between the tangent T2' to the periphery C2 of the rotor 110 and the tangent T2 to the chord K of the blade concerned at the outlet point S.

[0049] Preferably, the outlet flow angle p2 is equal to approximately 22°. More generally, this angle is between 19° and 25°.

[0050] All of the entry points E of the blades 112 are arranged equidistantly in pairs, preferably along the internal circle C1 of internal radius R1 and the blades all have the same chord profile, so that, as already mentioned, the blades are uniformly distributed over the face of the rotor 110.

[0051] An example of a blade chord will now be described with reference to Figure 4 which is a repeat of Figure 3.

[0052] To define the chord K of this blade 112, we first define an orthonormal reference frame (X,Y), included in a plane orthogonal to the axis of rotation of the rotor 110. This frame (X,Y) is centered on the center of rotation O of the rotor 110 in this plane. In other words, the origin (X=0, Y=0) of the frame coincides with the center of rotation O. This frame is oriented so that the abscissa axis X of the frame passes through the nose of the blade 112 and the ordinate axis Y of the frame passes through the root of the blade 112 (in particular an intrados of the root of the blade concerned).

[0053] Preferably, the chord K of the blade 112 extends according to a profile defined by a polynomial of order 4, defined in the orthonormal reference frame (X,Y) by the following equation: y = —4. 10 -5 . % 4 + 1.1. 10 -3 . % 3 — 4.45. 10 -2 x 2— 0.4861. x + 10.806 , where x and y denote the two-dimensional coordinates in the orthonormal frame, such that x is between -3 and 24 mm. The correlation coefficient R 2 allowing us to assess the precision of this estimate is 0.9994.

[0054] In the present example, all the other blades 112 have a chord defined by the same polynomial by rotation of the orthonormal frame (X,Y) around the axis of rotation O. In other words, each blade 112 has the same profile.

[0055] The height profile of the blades 112 will now be described with reference to FIG. 5 which is an exploded perspective view of the assembly formed by the rotor 110 and the flange 120.

[0056] Preferably, each blade 112 has a wetted inlet height b1 at the inlet point E equal to 3.7 mm. More generally, this height b1 is between 3.6 and 3.8 mm.

[0057] Preferably, each blade 112 has a wetted exit height b2 at the exit point S equal to 2.4 mm. More generally, this height b2 is between 2.3 and 2.5 mm.

[0058] By definition, wetted height refers to the dimension of the blade in the direction parallel to the axis of rotation of the pump, for the part of the blade immersed in the flow.

[0059] In the present example, the height of each blade 112 varies between its entry point E and its exit point S. Preferably, the wetted height at the entry b1 is slightly higher than the wetted height at the exit b2, by approximately 1 / 3.

[0060] In Figure 5 is shown in solid lines, an example of transverse profile P of a blade 112. According to this example, the blade 112 has a constant height equal to b2 along the major part of the external radius R2 of the rotor 110 from its periphery C2, in particular over 80%, or even 90% of its chord length, and increases in an increasing manner in the central zone C1 of the rotor 110 to reach a maximum height at the center O of the rotor 110 equal to b1. Such a characteristic facilitates a transition of the fluid between the introduction channel of the flange and the fluid passages between the blades. After this transition zone, the cross section of the fluid passages is substantially constant.

[0061] With reference to the figures described above and as already indicated, the blades 112 of the rotor 110 are identical, i.e. they all have the same chord defined by a polynomial and the same height profile. However, in other embodiments, the blades will not necessarily all be identical.

[0062] The performance of the centrifugal pump as described above was evaluated in terms of efficiency from measurement results which will now be described with reference to Figure 6.

[0063] By definition, the total efficiency p of a centrifugal pump is the product of the hydraulic efficiency ph and the mechanical efficiency r| m , as defined by the following equation:

[0064] [Math. Q: volume flow rate (in L / h); P: pressure (mbar) C: torque (Nm) U: voltage (V) I: current (A) co: rotation speed (rad / s)

[0065] For the centrifugal pump 100 as described above, figure 6 represents as a function of the volume flow rate Q expressed in L / h on the abscissa: on a curve GP, the pressure P expressed in mbar on the ordinate; on a curve G n h, the hydraulic efficiency on the ordinate; and on a curve G n , the total yield in ordinates.

[0066] These curves were obtained by measurement when the centrifugal pump 100 is configured at an operating point F for which the rotation speed œ of the rotor 110 is maintained at 7300 revolutions per minute (rpm). For this operating point, it is found that the total efficiency p is maximum, approximately equal to 0.47 while the hydraulic efficiency p h is maximum, approximately equal to 0.70.

[0067] Figure 7 illustrates the performance of an electric motor configured to drive the centrifugal pump 100 according to the invention used to circulate the fluid of the cooling circuit in an electric vehicle, when the pump is configured at the operating point F described with reference to Figure 6.

[0068] The performance of the electric motor was measured in terms of electrical power and torque. The results of these measurements are represented, as a function of the volume flow rate Q expressed in L / h on the abscissa, by a curve Gp e representing the electric power P e expressed in W on the ordinate; and by a curve Gc representing the torque C expressed in Nm.

[0069] By definition, the electric power Pe is defined by the product of an electric voltage U and an electric current I.

[0070] From these results, we see that for a volume flow rate corresponding to the predefined operating point F, i.e. Q approximately equal to 2300 L / h, the torque and the electrical power have almost reached their maximum value.

Claims

Claims Claim 1 Centrifugal hydraulic pump (100) comprising: a rotor (110) with an axis of rotation (A); one or more distributed blades (112) on one face of the rotor, the blade(s) extending from a central zone (C1) of the rotor to a peripheral zone (C2) of the rotor; the blade(s) having a chord (K) extending between a blade root forming an entry point (E), located in the central zone (C1) of the rotor, and a blade nose forming an exit point (S), located in the peripheral zone (C2) of the rotor; the entry point (E) and the exit point (S) forming with the axis of rotation (A) of the rotor, in a plane orthogonal to said axis (A), a deployment angle ( <p) compris entre 75° et 110°, de préférence supérieur à 90°, voire supérieur à 95°, plus précisément égal à environ 102°. Claim 2 Pump according to claim 1, in which each blade (112) is configured so that it has an inlet flow angle (P1) of between 16° and 22°, preferably equal to 19°, the inlet flow angle (pi) being formed between a tangent (TT) to the central zone (C1) and a tangent (T1) to the chord (K) of the blade concerned at the inlet point (E). Claim 3 Pump according to claim 1 or 2, wherein each blade (112) is configured so that it has an outlet flow angle (P2) of between 19° and 25°, preferably equal to 22°, the outlet flow angle (P2) being formed between a tangent (T2') to the periphery (C2) of the rotor and a tangent (T2) to the chord (K) of the blade concerned at the outlet point (S). Claim 4 Pump according to any one of claims 1 to 3, wherein the rotor (110) has an internal radius (R1) defining the central zone (C1), said radius being between 9 mm and 11 mm, preferably equal to 10 mm. Claim 5 Pump according to any one of claims 1 to 4, wherein the rotor (110) has an external radius (R2) defining the peripheral zone (C2), said radius being between 22 mm and 25 mm, preferably equal to 23.2 mm Claim 6 Pump according to any one of claims 1 to 5, in which each blade (112) has an inlet wetted height (b1) at the inlet point (E), between 3.6 and 3.8 mm, preferably equal to 3.7 mm. Claim 7 Pump according to any one of claims 1 to 6, in which each blade (112) has an outlet wetted height (b2) at the outlet point (S), between 2.3 and 2.5 mm, preferably equal to 2.4 mm. Claim 8 Pump according to any one of claims 1 to 7, in which the chord (K) of each blade (112) extends according to a profile defined by a polynomial of order 4, in an orthonormal reference frame (X,Y) included in a plane orthogonal to said axis of rotation (A) of the rotor and centered on said axis of the rotor, the abscissa axis (X) of the reference frame passing through the nose (S) and the ordinate axis (Y) of the reference frame passing through the root (E) of the blade concerned (112), the polynomial being defined by the following equation: y = -4. 10 -5 . % 4 + 1.

1. 10 -3 . % 3 - 4.

45. 10 -2 % 2 - 0.4861. x + 10.806, where x and y denote the two-dimensional coordinates in the orthonormal frame (X,Y), such that x is between -3 and 24 mm. Claim 9 Pump according to any one of claims 1 to 8, wherein the pump has a number of blades between 5 and 10, preferably equal to 8. Claim 10 Pump according to any one of claims 1 to 9, in which each blade has a thickness of between 0.8 and 2 mm, preferably equal to 1 mm.

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