Centrifugal pump with optimized efficiency

Abstract

The invention relates to a centrifugal pump (10) comprising: - a volute (20) including a fluid suction port (21) and a fluid discharge port (22), - an impeller (30) installed in the volute (20) and having an inlet pipe (31), said inlet pipe (31) extending along the axis of the suction port (21), in particular in line with said suction port (21), and the inlet pipe (31) having an edge (310), said centrifugal pump (10) being characterized in that it comprises at least one first ring (40), said first ring (40) being installed between the edge (310) of the inlet pipe (31) and the volute (20), said first ring (40) comprising a material different from that composing the volute (20) and that composing the impeller (30), in in particular said first ring (40) comprising a material configured to wear away by friction against the volute (20) or against the paddle wheel (30).Figure from the summary: Figure 2.

Description

Title of the invention: Centrifugal pump with optimized efficiency technical field

[0001] The present invention relates to a centrifugal pump driven by an electric motor. The invention further relates to a vehicle cooling system comprising said pump, and to an electric or hybrid vehicle comprising said cooling system.

[0002] The invention relates to the technical field of centrifugal pumps, and more particularly to centrifugal pumps whose electric motor is a radial or axial air gap motor. This type of pump is particularly suitable for vehicles, and more preferably for hybrid or electric vehicles. Prior art

[0003] Currently, more and more vehicles are electric or hybrid vehicles, with batteries that are no longer used solely for starting or powering certain components, but also for propulsion. Consequently, these vehicles require a greater number of batteries for their proper operation.

[0004] Each battery consists of individual cells, each cell producing both energy and heat. It is important, however, that the heat emitted by these cells be well dissipated, as excessive heat can cause irreversible damage to the cells, leading to a reduction or even a loss of their functionality. Therefore, efficient battery cooling must be provided. This cooling is generally achieved by a heat transfer fluid circulating in a cooling circuit around and within the battery.

[0005] The heat transfer fluid is used to regulate the temperature of the batteries and can be circulated by a centrifugal pump. The pump comprises at least one impeller installed in a housing, said impeller being driven by an electric motor so as to move the fluid.

[0006] Centrifugal pumps with an axial air gap are known, comprising an impeller mounted in a volute, and an electric motor driving said impeller and enabling the circulation of the fluid. The motor consists of a stator positioned in a pump housing and a rotor associated with said impeller. The volute also includes a suction port and a fluid discharge port, the main fluid circuit being arranged between said suction and discharge ports of the pump. Thus, the fluid circulates within a first circuit, called the main circuit, from the suction port and around the impeller blades. The fluid circulates through the impeller blades before reaching the discharge port. It also flows through a second circuit, known as the return or secondary leakage circuit. This second circuit originates from the impeller blades, then passes between the impeller and the volute, before returning to the suction port. This secondary circuit negatively impacts the pump's hydraulic efficiency.

[0007] The invention aims to overcome at least one of the drawbacks of the aforementioned prior art. More particularly, the invention aims to reduce the leakage rate in the secondary leakage circuit, so as to improve the pump torque at an equivalent discharge flow rate. Summary

[0008] To this end, the present invention proposes a centrifugal pump adapted for circulating a heat transfer fluid comprising: - a volute comprising a suction port and a fluid discharge port, - an impeller installed in the volute and comprising an inlet tube, said inlet tube extending in the axis of the suction port, in particular in the continuation of said suction port, and the inlet tube comprising an edge, said centrifugal pump being characterized in that it comprises at least one first ring, said first ring being installed between the edge of the inlet tube and the volute, said first ring comprising a material different from that composing the volute and that composing the impeller, in particular said first ring comprising a material configured to wear by friction against the volute or against the impeller.

[0009] The heat transfer fluid can be any fluid configured to allow thermal regulation, for example, of a vehicle engine or, more specifically, of a battery. This fluid can be any fluid capable of absorbing and transferring heat; it can also be a gas such as air, water, or a glycol compound.

[0010] The suction port allows the fluid to enter the pump, and the discharge port allows it to be discharged.

[0011] The first ring comprises a material configured to wear through contact with the volute or the impeller, due to friction caused by the rotation of the impeller within the volute. To achieve this, said material has a lower hardness than the material composing the volute and the material composing the impeller, so as to ensure that the first ring is indeed the element that wears. In particular, the first ring comprises a material having a Shore A hardness between 30 and 50 Shore A.

[0012] Thus, when the first crown is mounted in contact with the volute and the paddle wheel, the rotation of the latter causes wear on the first crown.

[0013] According to one embodiment of the invention, the pump includes a hood, the impeller being housed in the volume formed by the assembly of the volute and said hood.

[0014] The assembly of the volute and the hood forms a sealed envelope around the impeller so as to keep the heat transfer fluid in the pump and prevent leaks.

[0015] According to one embodiment of the invention, said at least first crown is installed in a complementary cavity of the volute, the inlet tube of the paddle wheel being housed in said complementary cavity.

[0016] The complementary cavity has a shape complementary to the inlet pipe of the impeller, said inlet pipe being housed within the complementary cavity. The combination of the inlet pipe and the complementary cavity improves the guidance of the heat transfer fluid.

[0017] According to an example of an embodiment of the invention, the passage surface of the suction orifice of the volute is substantially identical to the passage surface of the inlet tube of the paddle wheel.

[0018] According to an embodiment of the invention, said pump comprises: - a main fluid circulation circuit arranged between the suction port and the discharge port, which main circuit passes through the inlet pipe, - a secondary leak circuit separate from the main circuit, arranged between the discharge port and the suction port, which secondary circuit is formed by a space located between an external wall of the impeller and an internal wall of the volute, said centrifugal pump being characterized in that said at least first ring is installed in the secondary leak circuit, so as to at least partially block said secondary leak circuit.

[0019] The presence of the first ring in the secondary leakage circuit partially blocks said circuit. Thus, the leakage rate of the fluid in the secondary leakage circuit is limited, as the fluid pressure losses are increased due to the reduction in the flow area between the edge of the impeller inlet pipe and the volute. Consequently, the pump's efficiency is improved, while its energy consumption is reduced. The reduced energy consumption of the pump allows the batteries to operate for longer periods. This additional energy can be used by the vehicle, notably to increase its operating time.

[0020] According to an example of an embodiment of the invention, said at least first crown is integral with said volute or said paddle wheel.

[0021] In this way, the first crown is held in position.

[0022] According to one embodiment of the invention, the first ring is integral with the volute. According to this embodiment, the material of the first ring configured to wear is preferably disposed on the side of the first ring located opposite the paddle wheel. In this way, in the event of contact between the first ring and the paddle wheel, the rotation of the paddle wheel causes the first ring to rub against the paddle wheel and wears down the material configured to wear.

[0023] According to one embodiment of the invention, the first ring is integral with the impeller. In this embodiment, the material of the first ring configured to wear is preferably located on the side of the first ring opposite the volute. In this way, in the event of contact between the first ring and the volute, the rotation of the impeller causes the first ring to rub against the volute and wear down the material configured to wear.

[0024] According to one embodiment of the invention, the pump comprises a first ring, integral with the volute, and a second ring, integral with the impeller. According to this embodiment, the material of the first ring configured to wear is preferably arranged on the side of the first ring opposite the second ring, while the material of the second ring configured to wear is preferably arranged on the side of the second ring opposite the first ring. In this way, in the event of contact between the first and second rings, the rotation of the impeller causes friction between the first ring and the second ring, resulting in wear of the materials configured to wear.

[0025] According to an example of an embodiment of the invention, said at least first crown is overmolded with said volute or said paddle wheel.

[0026] Such an embodiment facilitates the manufacture of the pump.

[0027] According to an embodiment of the invention, the pump comprises a first ring, integral with the volute, and a second ring, integral with the impeller, said first ring being overmolded with said volute and said second ring being overmolded with the impeller.

[0028] According to an embodiment of the invention, a distance separating said at least first ring from the volute or said at least first ring from the paddle wheel is less than 0.3 mm, preferably less than 0.2 mm, even more preferably less than 0.1 mm.

[0029] According to an example of an embodiment of the invention, said first at least crown comprises a body, said body forming a ring, in particular a ring of uniform section.

[0030] According to an embodiment of the invention, a distance separating at least a portion of said at least first ring from the volute or at least a portion of said at least first ring from the paddle wheel is less than 0.3 mm, preferably less than 0.2 mm, even more preferably less than 0.1 mm.

[0031] Preferably, a distance separating at least a portion of the body of said at least first ring of the volute or at least a portion of the body of said at least first ring of the paddle wheel is less than 0.3 mm, preferably less than 0.2 mm, even more preferably less than 0.1 mm.

[0032] The hydraulic efficiency of the pump is significantly improved when the distance separating the first ring, preferably at least a portion of the first ring, even more preferably at least a portion of the body of the first ring, from the volute or the first ring, preferably at least a portion of the first ring, even more preferably at least a portion of the body of the first ring, from the impeller is less than 0.3 mm, preferably less than 0.2 mm, even more preferably less than 0.1 mm.

[0033] According to an embodiment of the invention, said at least first crown comprises at least one lug, in particular three lugs, said lugs protruding from said body and being directed towards the volute or towards the paddle wheel.

[0034] During the mounting of the impeller in the pump, depending on whether the first ring is integral with the volute or the impeller, the lugs are in contact with the impeller or the volute. The lugs are configured to wear through friction against the impeller or the volute, due to the rotation of the impeller. In this way, the wear of the portion of the first ring in contact with the impeller or the volute is improved and accelerated.

[0035] According to one embodiment of the invention, said at least one lug may be triangular, rectangular or rounded in shape.

[0036] According to another embodiment, the lugs form sinusoidal waves on the body of the first crown.

[0037] According to an embodiment of the invention, said at least one lug comprises the material configured to wear down.

[0038] A height of said at least one lug is less than 0.3 mm, preferably less than 0.2 mm, and even more preferably less than 0.1 mm. Said height is measured between a vertex and a base of said at least one lug, in particular between a vertex of said at least one lug and the body of the first ring.

[0039] According to this embodiment of the invention, when the lugs are in contact with the volute or the paddle wheel, the rotation of said paddle wheel causes wear on the lugs. This wear allows the formation of an air gap between the first ring and the volute or the first ring and the paddle wheel. This effect is achieved more quickly in the presence of lugs than when the body of the first ring is in direct contact with the volute or the paddle wheel. In other words, the lugs make it possible to obtain the desired effect in a minimum amount of time, namely, to obtain a minimum distance between the first ring and the volute or between the first ring and the paddle wheel.

[0040] According to one embodiment of the invention, the volute and / or the paddle wheel comprises polypropylene or polyamide.

[0041] According to one embodiment of the invention, said at least first ring comprises a resin or an organic matrix composite material.

[0042] The pump's volute and impeller are typically made of polypropylene or polyamide-type materials. Resins and organic matrix composite materials have a lower hardness than polypropylene and polyamide. Friction of the first ring of resin or organic matrix composite material against the impeller or volute will thus cause wear of said first ring.

[0043] According to one embodiment of the invention, the pump is powered by an electric motor.

[0044] According to one embodiment of the invention, the pump comprises a casing, said casing forming a housing in which a rotor and a stator are housed, said rotor being connected to the impeller by means of a shaft.

[0045] The invention also relates to a vehicle cooling device comprising a cooling circuit in which a heat transfer fluid circulates and a centrifugal pump configured to move said fluid in said circuit, characterized in that the pump conforms to the invention.

[0046] The invention also relates to an electric or hybrid vehicle comprising at least one battery pack and a cooling device for said battery pack, which device includes a cooling circuit in which a heat transfer fluid circulates and a centrifugal pump configured to move said fluid in said circuit, characterized in that the pump conforms to the invention.

[0047] The invention also relates to a method for manufacturing a centrifugal pump adapted for circulating a heat transfer fluid, said pump comprising: - a volute comprising a fluid suction orifice and a fluid discharge orifice, - an impeller installed in the volute and comprising an inlet pipe, said inlet pipe extending along the axis of the suction orifice, in particular in line with said suction orifice, and the inlet pipe comprising an edge, - at least one first ring, said first ring being installed between the edge of the inlet pipe and the volute, said first ring being composed of a material different from that composing the volute and that composing the impeller, in particular a material composing at least part of the first ring being configured to wear by friction against the volute or against the impeller, said method includes the following steps: - installation, for example by overmolding or gluing, of the first ring, on the volute, opposite the edge or on the edge, opposite the volute, - installation of the paddle wheel in the volute, so that the paddle wheel, the volute and the first ring are in contact.

[0048] In this way, the space left free between the volute and the paddle wheel, at the level of the latter's inlet pipe, is minimized. This space is at least partially filled by the first ring.

[0049] According to an example of an embodiment of the invention, the method comprises the following steps: - connect the paddle wheel to an electric motor, specifically to a shaft connected to an electric motor, - to maintain the volute in position to prevent its rotation, - to rotate the paddle wheel in the volute, in particular until the said at least first ring, due to wear, by friction, against the paddle wheel or the volute, is no longer in contact with the paddle wheel or the volute.

[0050] To control the quality of the pumps, they are routinely tested. During these tests, the pumps are driven by a test motor that rotates the impeller within the volute. This test motor preferably has a higher torque than the motor intended for the pump in normal operation. During these tests, the rotation of the impeller causes wear on the first ring, thus ensuring that, in normal operation after testing, the impeller, the first ring, and the volute are not in contact.

[0051] According to an embodiment of the invention, said at least first ring of the method comprises a body and at least one lug, in particular three lugs, said lugs protruding from said body and being directed towards the volute or towards the paddle wheel, the lugs having a height of less than 0.3 mm, preferably less than 0.2 mm, more preferably less than 0.1 mm.

[0052] The lugs will wear out more quickly than the body of the first ring, which makes it possible to obtain the desired effect in a minimum of time, namely to obtain a minimum distance between the first ring and the volute or the first ring and the paddle wheel. Brief description of the drawings

[0053] Other features, details and advantages will become apparent upon reading the detailed description below, and upon analysis of the accompanying drawings, on which:

[0054] [Fig-1] is a perspective view of a centrifugal pump according to the invention.

[0055] [Fig.2] is a cross-sectional view of the centrifugal pump of [Fig. 1].

[0056] [Fig.3] is a perspective view of the volute of the centrifugal pump of [Fig.1].

[0057] [Fig.4] is a perspective view of the impeller of the centrifugal pump of the [Fig.l].

[0058] [Fig.5] is a perspective view of an example of the realization of a first crown according to the invention.

[0059] [Fig.6] is a cross-sectional view of the centrifugal pump of [Fig.1] centered on the first ring.

[0060] [Fig.7] illustrates results of measurements of the hydraulic efficiency of a centrifugal pump according to the invention as a function of the distance between the first ring and the volute. Description of the implementation methods

[0061] To facilitate reading the figures, the different elements are not necessarily drawn to scale. In these figures, identical elements bear the same reference numerals. Certain elements or parameters may be indexed, that is, designated, for example, as first element or second element, or first parameter and second parameter, etc. This indexing aims to differentiate similar, but not identical, elements or parameters. This indexing does not imply a priority of one element or parameter over another. The designations 'first', 'second', 'third', etc., can thus be interchanged.

[0062] Generally speaking, a vehicle, such as a motor vehicle, may include a cooling system. This cooling system includes a cooling circuit in which a heat transfer fluid circulates, set in motion by a centrifugal pump 10.

[0063] The vehicle also includes at least one battery pack. In the case of hybrid and electric vehicles, several battery packs are necessary not only to enable the operation of the vehicle's components, but also to enable its movement. Each battery pack is composed of individual cells, each cell being capable of producing the energy required for the vehicle's operation. However, energy production is coupled with heat production, which can lead to a decrease in cell efficiency and / or deformation of the cells.

[0064] Therefore, the cooling system provided in the vehicle can be designed for at least the battery pack(s) so as to regulate their temperature. This cooling system includes the cooling circuit in which the heat transfer fluid circulates, and is configured to regulate the temperature of the battery pack cells around which the fluid circulates. This heat transfer fluid is known to humankind. of the trade, and can be, for example, air, water, or a dielectric fluid. The movement of such a fluid in the cooling circuit is achieved by a centrifugal pump 10. This pump 10 is shown in Figures 1 and 2.

[0065] Figures 1 and 2 represent a centrifugal pump 10, in particular for a vehicle, especially for a hybrid or electric vehicle, according to an example of implementation of the invention.

[0066] The centrifugal pump 10 is adapted for circulating a heat transfer fluid. Said pump 10 comprises: - a volute 20 comprising a suction port 21 and a discharge port 22 for the fluid, - a paddle wheel 30 installed in the volute 20 and comprising an inlet tube 31, said inlet tube 31 extending in the axis of the suction port 21, in particular in the extension of said suction port 21, and the inlet tube 31 comprising an edge 310, said centrifugal pump 10 being characterized in that it comprises at least a first ring 40, said first ring 40 being installed between the edge 310 of the inlet tube 31 and the volute 20.

[0067] Said first ring 40 comprises a material different from that composing the volute 20 and that composing the paddle wheel 30. In particular, said first ring 40 comprises a material configured to wear by friction against the volute 20 or against the paddle wheel 30.

[0068] The heat transfer fluid can be any fluid configured to allow thermal regulation, for example, of a vehicle engine or, more specifically, of a battery. This fluid can be any fluid capable of absorbing and transferring heat; it can also be a gas such as air, water, or a glycol compound.

[0069] The pump 10 includes a hood 51, the impeller 30 being housed in the volume formed by the assembly of the volute 20 and said hood 51.

[0070] The assembly of the volute 20 and the hood 51 forms a sealed envelope around the impeller 30 so as to keep the heat transfer fluid in the pump 10 and prevent leaks.

[0071] The suction port 21 allows the fluid to enter the pump 10, and the discharge port 22 allows it to be discharged.

[0072] The first ring 40 comprises a material configured to wear down in contact with the volute 20 or the paddle wheel 30, due to the friction related to the rotation of the paddle wheel 30 in the volute 20. To achieve this, said material has a lower hardness than the material composing the volute 20 and than the material composing the paddle wheel 30, so as to ensure that the first ring 40 is indeed the element that wears down. In particular, the first ring comprises a material having a Shore A hardness between 30 and 50 Shore A.

[0073] Thus, when the first ring 40 is mounted in contact with the volute 20 and the paddle wheel 30, the rotation of the latter causes wear on the first ring 40.

[0074] The first ring 40 is installed in a complementary cavity 24 of the volute 20, shown [Fig. 3]. The inlet pipe 31 of the paddle wheel 30 is housed in said complementary cavity 24.

[0075] The complementary cavity 24 has a shape complementary to the inlet tube 31 of the impeller 30, said inlet tube 31 being housed in the complementary cavity 24. The combination of the inlet tube 31 and the complementary cavity 24 improves the guidance of the heat transfer fluid.

[0076] According to an example of an embodiment of the invention, illustrated in particular [Fig.2], the passage surface of the suction orifice 21 of the volute 20 is substantially identical to the passage surface of the inlet tube 31 of the paddle wheel 30.

[0077] As shown in [Fig.2], the pump 10 comprises: - a main fluid circulation circuit 1 arranged between the suction port 21 and the discharge port 22, which main circuit 1 passes through the inlet pipe 31, - a secondary leakage circuit 2 separate from the main circuit 1, arranged between the discharge port 22 and the suction port 21, which secondary circuit 2 is formed by a space located between an external wall 32 of the paddle wheel 30 and an internal wall 23 of the volute 20, said centrifugal pump 10 being characterized in that said at least first ring 40 is installed in the secondary leakage circuit 2, so as to block at least partially said secondary leakage circuit 2.

[0078] The presence of the first ring 40 in the secondary leakage circuit 2 partially blocks said circuit. The first ring 40 therefore limits the recirculation of the fluid in the secondary leakage circuit 2. Thus, the leakage rate of the fluid in the secondary leakage circuit 2 is limited, the pressure losses of the fluid being increased due to the reduction of the passage area between the edge 310 of the inlet pipe 31 of the impeller 30 and the volute 20.

[0079] As a result, the efficiency of the pump 10 is improved, while its energy consumption is reduced. The reduced energy consumption of the pump 10 allows the batteries to operate for longer periods. This additional energy can be used by the vehicle, notably increasing its operating time.

[0080] According to the embodiment shown, said at least first ring 40 is integral with said paddle wheel 30. In this way, the first ring is held in position.

[0081] According to an embodiment of the invention, not shown, the first ring 40 is fixed to the volute 20. According to this embodiment, the material of the first ring 40 configured to wear is preferably disposed on the side of the first ring 40 located opposite the paddle wheel 30. In this way, in the event of contact between the first ring 40 and the paddle wheel 30, the rotation of the paddle wheel 30 causes the first ring 40 to rub against the paddle wheel 30 and the material configured to wear is worn.

[0082] According to the embodiment of the invention shown in particular in figures 2 and 6, the first ring 40 is fixed to the paddle wheel 30. According to this embodiment, the material of the first ring 40 configured to wear is preferably disposed on the side of the first ring 40 located opposite the volute 20. In this way, in the event of contact between the first ring 40 and the volute 20, the rotation of the paddle wheel 30 causes the first ring 40 to rub against the volute 20 and the material configured to wear is worn.

[0083] According to an embodiment of the invention, not shown, the pump 10 comprises a first ring 40, integral with the volute 20, and a second ring, integral with the impeller 30. According to this embodiment, the material of the first ring 40 configured to wear is preferably disposed on the side of the first ring 40 located opposite the second ring, while the material of the second ring configured to wear is preferably disposed on the side of the second ring located opposite the first ring 40. In this way, in the event of contact between the first ring 40 and the second ring, the rotation of the impeller 30 causes the first ring 40 to rub against the second ring and wear the materials configured to wear.

[0084] According to one embodiment of the invention, said at least first crown 40 is overmolded with said volute 20 or said paddle wheel 30.

[0085] Such an embodiment facilitates the manufacture of the pump 10.

[0086] According to an example of an embodiment of the invention, not shown, the pump 10 comprises a first ring 40, integral with the volute 20, and a second ring, integral with the impeller 30, said first ring 40 being overmolded with said volute 20 and said second ring being overmolded with the impeller 30.

[0087] According to an example of an embodiment, illustrated in particular [Fig.5], said at least first crown 40 comprises a body 42, said body 42 forming a ring, in particular a ring of uniform section.

[0088] According to the illustrated embodiment [Fig.5], said at least first crown comprises at least one lug 41, in particular three lugs 41, said lugs 41 protruding from said body 42 and being directed towards the volute 20 or towards the paddle wheel 30.

[0089] When the impeller 30 is mounted in the pump 10, depending on whether the first ring 40 is fixed to the volute 20 or to the impeller 30, the lugs 41 are in contact with the impeller 30 or with the volute 20. The lugs 41 are configured to wear by friction in contact with said impeller 30 or said volute 20, due to the rotation of said impeller 30. In this way, the wear of the portion of the first ring 40 in contact with the impeller 30 or with the volute 20 is improved and accelerated.

[0090] Said at least one lug 41 may be triangular, rectangular or rounded in shape.

[0091] According to an exemplary embodiment of the invention, said at least one lug 41 comprises the material of the first 40 crown configured to wear.

[0092] A height H of said at least one lug 41 is less than 0.3 mm, preferably less than 0.2 mm, and even more preferably less than 0.1 mm. Said height H is measured between a vertex and a base of said at least one lug 41, in particular between a vertex of said lug 41 and the body 42 of the first ring 40.

[0093] According to this embodiment of the invention, when the lugs 41 are in contact with the volute 20 or the impeller 30, the rotation of said impeller 30 causes wear on the lugs 41. This wear allows the formation of an air gap between the first ring 40 and the volute 20 or the first ring 40 and the impeller 30. This effect is achieved more quickly in the presence of lugs 41 than when the body 42 of the first ring 40 is directly in contact with the volute 20 or the impeller 30. In other words, the lugs 41 make it possible to obtain the desired effect in a minimum amount of time, namely obtaining a minimum distance between the first ring 40 and the volute 20 or between the first ring 40 and the impeller 30.

[0094] As shown [Fig.6], a distance D separating at least a portion of the body 42 from said at least first crown 40 of the volute 20 is less than 0.3 mm, preferably less than 0.2 mm, again preferably less than 0.1 mm.

[0095] The hydraulic efficiency of the pump 10 is markedly improved when the distance separating at least a portion of the body 42 from the first ring 40 of the volute 20 or at least a portion of the body 42 from the first ring 40 of the impeller 30 is less than 0.3 mm, preferably less than 0.2 mm, even more preferably less than 0.1 mm.

[0096] The volute 20 and / or the paddle wheel 30 comprises polypropylene or polyamide.

[0097] Said at least first crown 40 is made of resin or organic matrix composite material.

[0098] The volute 20 and the impeller 30 of the pump 10 are typically made of polypropylene or polyamide-type materials. Resins and organic matrix composite materials have a lower hardness than polypropylene or polyamide. Friction of the first ring 40 made of organic matrix composite material against the impeller 30 or the volute 20 will thus cause wear of said first ring 40.

[0099] The pump 10 is powered by an electric motor, not shown.

[0100] The pump includes a casing, not shown, said casing forming a housing in which a rotor and a stator are housed, said rotor being connected to the impeller by means of a shaft.

[0101] The invention also relates to a method for manufacturing a centrifugal pump 10 adapted for circulating a heat transfer fluid, said pump 10 comprising: - a volute 20 comprising a suction port 21 and a discharge port 22 for the fluid, - a paddle wheel 30 installed in the volute 20 and comprising an inlet tube 31, said inlet tube 31 extending along the axis of the suction orifice 21, in particular in the continuation of said suction orifice 21, and the inlet tube 31 comprising an edge 310, - at least one first ring 40, said first ring 40 being installed between the edge 310 of the inlet pipe 31 and the volute 20, said first ring 40 being composed of a material different from that composing the volute 20 and that composing the paddle wheel 30, in particular a material composing at least part of the first ring 40 being configured to wear by friction against the volute 20 or against the paddle wheel 30, said method includes the following steps: - installation, for example by overmolding or by gluing, of the first ring 40, on the volute 20, opposite the edge 310 or on the edge 310, opposite the volute 20, - installation of the paddle wheel 30 in the volute 20, so that the paddle wheel 30, the volute 20 and the first ring 40 are in contact.

[0102] In this way, the gap left between the volute 20 and the paddle wheel 30, at the level of the inlet pipe 31 of the latter, is minimized. This gap is at least partially filled by the first ring 40.

[0103] Said method may also include the following steps: - connect the paddle wheel 30 to an electric motor, specifically to a shaft connected to an electric motor, - to maintain the volute 20 in position to prevent its rotation, - to rotate the paddle wheel 30 in the volute 20, in particular until said at least first ring 40, due to wear by friction against the paddle wheel 30 or the volute 20, is no longer in contact with the paddle wheel 30 or the volute 20.

[0104] To check the quality of the pumps 10, they are routinely tested. During these tests, the pumps 10 are driven by a test motor that rotates the impeller 30 within the volute 20. This test motor preferably has a higher torque than the motor intended for the pump 10 in normal operation. During these tests, the rotation of the impeller 30 causes wear on the first ring 40, thus ensuring that, in normal operation after testing, the impeller 30, the first ring 40, and the volute 20 are not in contact.

[0105] The performance of the centrifugal pump 10 as described above has been evaluated in terms of hydraulic efficiency from measurement results which will now be described with reference to [Fig.7].

[0106] By definition, the total hydraulic efficiency qh of a centrifugal pump is defined by the following equation:

[0107] [Math. 1] • _ with 7^ Cw, Q: volumetric flow rate (in L / h); P: pressure (mbar) C: torque (Nm) co: rotational speed (rad / s)

[0108] For the centrifugal pump 10 as described above, [Fig.7] represents the hydraulic efficiency qh as a function of the distance D between the first ring 40 and the volute 20, D being expressed in millimeters.

[0109] These curves were obtained by measurement when the centrifugal pump 10 is configured at an operating point F for which the flow rate is 2700 L / h. For this operating point, it is observed that the total efficiency qh increases when the distance D between the first ring 40 and the volute 20 decreases, particularly when the distance D is less than 0.3 mm.

Claims

Demands

1. A centrifugal pump (10) adapted for circulating a heat transfer fluid comprising: - a volute (20) including a fluid suction port (21) and a fluid discharge port (22), - an impeller (30) installed in the volute (20) and having an inlet pipe (31), said inlet pipe (31) extending along the axis of the suction port (21), in particular in line with said suction port (21), and the inlet pipe (31) having an edge (310), said centrifugal pump (10) being characterized in that it comprises at least one first ring (40), said first ring (40) being installed between the edge (310) of the inlet pipe (31) and the volute (20), said first ring (40) comprising a material different from that composing the volute (20) and that composing the paddle wheel (30),in particular said first ring (40) comprising a material configured to wear away by friction against the volute (20) or against the paddle wheel (30).

2. Centrifugal pump (10) according to the preceding claim, wherein said at least first ring (40) is installed in a complementary cavity (24) of the volute (20), the inlet tube (31) of the impeller (30) being housed at least partially in said complementary cavity (24).

3. A centrifugal pump (10) according to any one of the preceding claims, wherein said pump (10) comprises: - a main fluid circulation circuit (1) arranged between the suction port (21) and the discharge port (22), which main circuit (1) passes through the inlet pipe (31), - a secondary leakage circuit (2) separate from the main circuit (1), arranged between the discharge port (22) and the suction port (21), which secondary circuit (2) is formed by a space located between an outer wall (32) of the impeller (30) and an inner wall (23) of the volute (20), said centrifugal pump (10) being characterized in that said at least the first ring (40) is installed in the secondary circuit leakage (2), so as to block at least partially said secondary leakage circuit (2).

4. Centrifugal pump (10) according to any one of the preceding claims, wherein said at least first ring (40) is integral with said volute (20) or said impeller (30).

5. Centrifugal pump (10) according to the preceding claim, wherein said at least first ring (40) is overmolded with said volute (20) or said impeller (30).

6. Centrifugal pump (10) according to any one of the preceding claims, wherein a distance (D) separating said at least first ring (40) from the volute (20) or said at least first ring (40) from the impeller (30) is less than 0.3 mm, preferably less than 0.2 mm, more preferably less than 0.1 mm.

7. Centrifugal pump (10) according to any one of the preceding claims, wherein said at least first ring (40) comprises a resin, in particular said at least first ring (40) is made of organic matrix composite material.

8. Vehicle cooling device comprising a cooling circuit in which a heat transfer fluid circulates and a centrifugal pump (10) configured to move said fluid in said circuit, characterized in that the pump (10) conforms to one of the preceding claims.

9. A method for manufacturing a centrifugal pump (10) adapted for circulating a heat transfer fluid, said pump (10) comprising: - a volute (20) including a suction port (21) and a discharge port (22) for the fluid, - an impeller (30) installed in the volute (20) and having an inlet pipe (31), said inlet pipe (31) extending along the axis of the suction port (21), in particular in line with said suction port (21), and the inlet pipe (31) having an edge (310), - at least one first ring (40), said first ring (40) being installed between the edge (310) of the inlet pipe (31) and the volute (20), said first ring (40) being composed of a material different from that composing the volute (20) and that composing the paddle wheel (30), in particular a component material at least in part the first ring (40) being configured to wear by friction against the volute (20) or against the paddle wheel (30), said method comprising the following steps: - installation, for example by overmolding or by bonding, of the first ring (40) on the volute (20), opposite the edge (310) or on the edge (310), opposite the volute (20), - installation of the paddle wheel (30) in the volute (20), so that the paddle wheel (30), the volute (20) and the first ring (40) are in contact.

10. Method according to the preceding claim, wherein said method comprises the following steps: - connecting the paddle wheel (30) to an electric motor, in particular to a shaft connected to an electric motor, - holding the volute (20) in position to prevent its rotation, - rotating the paddle wheel (30) in the volute (20) until said at least first ring (40), due to wear by friction against the paddle wheel (30) or the volute (20), is no longer in contact with the paddle wheel (30) or the volute (20).

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