"ROTOR GROUP OF A COOLING PUMP OF A VEHICLE COOLING

CIRCUI T"

[0001] This invention relates to a rotor group of a cooling pump for a cooling system of a vehicle. This invention also relates to the cooling pump that comprises said rotor group and the production method of said rotor group .

[0002] Known cooling pumps for a cooling system of a vehicle are typically suitable for moving a predefined quantity of cooling liquid towards predefined components of the vehicle that need to be cooled at specific times of the life cycle and use of the vehicle; these components include the engine, but also the turbo (or turbocharger ) , the exhaust gas recirculation system and the like.

[0003] In the state of the art, electric cooling pumps are known in which the movement of the impeller is obtained by means of an electronically controlled electric motor; these pumps comprise a plurality of components: among others, for example, the impeller, the rotation shaft on which it is mounted, the electric motor group operating on the shaft and the electronic means that control said electric motor.

[0004] These pumps, therefore, have several components that require complex manufacturing operations and complex assembly steps.

[0005] For the above reasons, these pumps are typically expensive and, given their complexity, often malfunction or have a rather short life cycle.

[0006] In order to obviate these problems, some components of these pumps are manufactured to meet high quality standards and they have particularly complex technological solutions.

[0007] The purpose of this invention is to provide a rotor groups that solves the drawbacks described above linked to the known solutions, such as to provide a limited number of components, obtainable through a simplified production and assembly process.

[0008] This purpose is achieved by a rotor group realised according to claim 1, by a cooling pump that comprises the rotor group according to claim 11 and by the production method of the rotor according to claim 12. The claims dependent on these refer to variants of preferred embodiments having further advantageous aspects.

[0009] The object of this invention is described below in detail, with the help of the accompanying figures, in which :

[0010] - Figure 1 is a perspective view in separate parts of a cooling pump comprising a rotor group according to a preferred embodiment of this invention;

[0011] - Figure 1' is a sectional view of the cooling pump of Figure 1;

[0012] - Figure 2 is a perspective view of the rotor group of this invention according to a preferred embodiment;

[0013] - Figure 2 is a sectional view along the plane V-V of the rotor group of Figure 2;

[0014] - Figures 3a and 3b are, respectively, an impeller- side perspective view and a perspective view on the opposite side of a rotor comprised in the rotor group shown in Figures 2 and 2';

[0015] - Figure 4 shows a perspective view of the shaft comprised in the rotor group shown in Figures 2 and 2';

[0016] - Figures 5a, 5b, 5c and 5d illustrate, in section, the moulding production steps of the rotor group according to a preferred embodiment, respectively, the step of accommodating the shaft and the rotor frame in the mould, a first step of injecting fluid material, a second step of injecting fluid material and a third and final step with extraction of the pin elements;

[0017] - Figures 5a' , 5b' , 5c' and 5d' show, in perspective views, the production steps of Figures 5a, 5b, 5c and 5d.

[0018] In the aforesaid figures, reference number 1 identifies, in its entirety, a rotor group covered by this invention. In particular, this rotor group 1 is used in the automotive sector as a component of a cooling pump 900 of a cooling circuit of a vehicle, as described below .

[0019] In a preferred embodiment, the rotor group 1 comprises a shaft 2 that extends along the axis X-X.

[0020] Preferably, the shaft 2 is a component in itself; preferably the shaft 2 is made of metal. However, as described below, the shaft 2, in some further embodiments, is an integral part of other components of the rotor group.

[0021] According to a preferred embodiment of the invention, the rotor group 1 comprises a rotor 3 fixed to a rotor end 23 of the shaft 2. As described below, the rotor 3 is suitable to be electromagnetically actuated in rotation by a stator 930 in turn controlled by electronic control means 931 (stator 930 and electronic control means 931 in turn comprised in the pump 900, object of the present invention, according to a preferred embodiment) ; wherein the shaft 2 is integral in rotation with the rotor 3.

[0022] So, preferably, the rotation of the rotor 3 corresponds to the rotation of the shaft 2.

[0023] According to a preferred embodiment, the rotor 3 includes a rotor frame 30 having a central cavity 320 in which the shaft 2 extends axially. [0024] In a preferred embodiment, the rotor 3 also comprises a plurality of polar cavities 310 arranged, preferably axially, in proximity to or on peripheral walls of the rotor frame 30, wherein said polar cavities are suitable to be engaged by the stator 930.

[0025] According to a preferred embodiment, the rotor 3 comprises a plurality of inserts 31 suitable to operate as rotor poles, preferably engaged by respective stator poles .

[0026] In the embodiment, in which the rotor frame 30 is provided with polar cavities 310, the inserts 31 are accommodated in said polar cavities 310. In further embodiments of the rotor 3, in which the rotor frame 30 does not have polar cavities 310, the inserts 31 are placed, for example glued, on the outer walls of the rotor frame 30.

[0027] Preferably, the inserts 31 are magnetically sensitive, that is to say suitable to be pushed by a magnetic field, to put the rotor 3 and shaft 2 in rotation. Preferably, the inserts 31 are made of ferromagnetic material, for example, are magnetisable .

[0028] According to a preferred embodiment, the rotor frame 30 is constituted by a plurality of sheet metal elements 30' axially aligned.

[0029] In other words, each sheet metal element 30' , preferably made of metal, has on its surface a central opening and a plurality of polar openings, in such a way as to create, once the sheet metal elements 30' are axially aligned, the corresponding central cavity 320 and any polar cavities 310.

[0030] Preferably, a sheet metal element 30' at the lateral end of the rotor frame has at least one radial protuberance 310' internally polar opening suitable to axially lock the respective insert 31 inserted axially in the rotor frame 30.

[0031] According to a preferred embodiment of the invention, the rotor group 1 comprises a main device 5. Specifically, the main device 5 has the dual function of providing support to the rotor 3 in its engagement with the shaft 2 and allowing rotation and circulation of the cooling liquid in the cooling circuit.

[0032] According to a preferred embodiment, the main device 5 is made in a single piece.

[0033] Preferably, the main device 5 is in a material chosen from polymeric materials, such as PPS (or polyphenylene sulphide) , preferably loaded in glass fibres. In other words, the main device 5 is formed in a semi-crystalline high performance thermoplastic material with excellent mechanical properties (resistance to deformation, rigidity and strength) and excellent thermal and chemical resistance, so as to be suitable to function immersed in the cooling fluid.

[0034] Preferably, the main device 5 extends, in height, along the axis X-X.

[0035] According to a preferred embodiment, the main device 5 comprises a rotor body 53 suitable to solidly support the rotor 3 at the rotor end 23 of the shaft 2.

[0036] Preferably, the rotor body 53 extends from the shaft 2, for example radially, until surrounding the rotor 3 in its entirety.

[0037] According to a preferred embodiment, the rotor body 53 is also suitable to lock and cover the inserts 31 placed on the rotor frame 30.

[0038] Preferably, the rotor body 53 is suitable to lock the respective inserts 31 in the polar cavities 310, preferably at the opposite side with respect to the side of the rotor frame 30 equipped with sheet metal element 30' comprising radial protuberances 310' .

[0039] Preferably, in addition, the rotor body 53 comprises an insulation layer 532 placed between the rotor 3 and the shaft 2. In other words, between rotor frame 30 and shaft 2 there is no contact, so that the rotor 3 is isolated from the external environment also in proximity of the central cavity 320.

[0040] In addition, according to a preferred embodiment, the rotor frame 30, in accordance with what is described above, has, parallel to the axis X-X, a plurality of through holes 350; in this embodiment, the rotor body 53 comprises a plurality of support pins 530 respectively accommodated in said through holes 350.

[0041] According to a preferred embodiment, the main device 5 also comprises an impeller body 54 that extends radially from the shaft 2 at an impeller end 24 opposite the rotor end 23. Preferably, the impeller body 54 is integral in rotation with the shaft 2, and is suitable to control the circulation of cooling liquid in the cooling circuit .

[0042] In other words, the main device 5 comprises a radial impeller body 54 that extends radially from the shaft 2. There is no limitation to the geometrical forms of the impeller body 54.

[0043] Preferably, the shaft 2 comprises at least one outer surface portion 28 provided with radial cavities to which the main device 5 is suitable to engage integrally. Preferably, both the rotor end 23 and the impeller end 24 have their own outer surface portions 28 provided with radial cavities, for example, they have knurled outer surfaces .

[0044] In a preferred embodiment, the main device 5 is moulded, in its entirety, directly around the shaft 2 and rotor 3.

[0045] Preferably, the rotor body 53, in its outer wall, has a maximum thickness of less than 1 millimetre, preferably 0.7 mm, so as to allow an effective functioning of the rotor 30 in its electrical engagement with the stator 930 when it is mounted comprised in a cooling pump 900, without affecting the efficiency of the pump .

[0046] According to a preferred embodiment, the main device 5 comprises a collar 55 that extends between the rotor body 53 and impeller body 54, in height along the axis X- X radially surrounding the shaft 2.

[0047] This invention also covers the cooling pump 900 of a cooling system of a vehicle comprising the rotor assembly 1 described above.

[0048] Preferably, the cooling pump 900 comprises a pump body 912 connectable with the channels (suction and discharge) of the cooling system. In particular, the pump body 912 includes a desired element, connectable with said channels, and a casing element, suitable to house the various components.

[0049] Preferably, the pump body 912 defines a water chamber 914 in which is housed the rotor group 1, i.e., the impeller body 54 and the rotor body 53 containing the rotor 3. Preferably, in the water chamber 914, is identified the impeller chamber 914' specifically suitable to contain the impeller body 54 and a predetermined amount of water placed in motion by it. Furthermore, the pump body 912 delimits a sealed chamber 913, sealingly separated from the water chamber 914, housing a stator group 930 and electronic control means 931 in turn comprised in the cooling pump 900.

[0050] Preferably, the stator group 930 is electromagnetically engaged with the rotor 30 on command of the electronic control means 931. In other words, the electronic control means 931 command the action of the stator 930 on the rotor 30 causing it to rotate and inducing in rotation also the impeller body 54.

[0051] In a preferred embodiment, the pump body 912, internally to it, comprises a central structure 912' suitable to rotationally support the rotor group 1 and to separate the water chamber 914 and the sealed chamber 913 from each other. Preferably, one end of the rotor group 1, in particular the shaft 2, is rotationally supported by the central structure 912' . Preferably, the pump body 912 comprises a support portion 912" suitable to rotationally support the other end of the rotor group 1.

[0052] In addition, this invention also covers the production method of the rotor group 1 described above. This production method is carried out by means of a press, for example a specially shaped mould 700, identifying a rotor compartment 703 and an impeller compartment 704 preferably in communication with each other through a collar compartment 705, wherein said areas have a shape substantially complementary to that of the corresponding components of the rotor group 1.

[0053] Preferably, the production method comprises the step of:

[0054] - housing, in the specially shaped mould 700, the rotor 3 and, possibly, the shaft 2 ;

[0055] - injecting liquid material to fill the mould 700, in other words fill the impeller compartment 704, the rotor compartment 703 and the collar compartment 705;

[0056] - waiting for the material to cool and solidify, constituting the main device 5;

[0057] - removing the main device 5 from the mould 700.

[0058] According to a preferred embodiment, the step of injecting the material is performed by injecting the material in a direction parallel to the axis X-X so that the material fills the impeller compartment 704 first and then the rotor compartment 703.

[0059] According to a preferred embodiment, the production method also comprises the step of:

[0060] - heating the rotor 3 and possibly the shaft 2.

[0061] Preferably, the rotor 3 and possibly the shaft 2 are heated to promote the adhesion of the plastic during the moulding step and not create mechanical and thermal stress due to the premature solidification of the material .

[0062] Preferably, the production method also comprises the step of:

[0063] - heating the mould 700 at a predefined temperature and keeping the mould at said temperature.

[0064] Preferably, the mould 700 is heated (and is kept in a predefined temperature range) to facilitate the flow of the plastic, avoiding thermal and mechanical stress due to premature solidification of the material. Preferably, the mould 700 is heated to a temperature higher than 145 °C.

[0065] Preferably, the press comprises a plurality of pin elements 710 that extend into the rotor compartment 703 of the mould, on which is threaded the rotor frame 30 in the respective through holes 350; when this press is used, the production method also comprises the step of:

[0066] - axially moving said pin elements 710 parallel to the axis X-X during the injection step of the material, in such a way that the liquid material injected enters inside said through holes 350, closing them and forming the support pins 530.

[0067] Innovatively, the rotor group, the cooling pump and the production method of the rotor group of this invention solve the problems of the known art. Advantageously, in fact, only a few components require specific assembly steps, as such components are made in a single process step, in a single piece. In other words, advantageously, the production and assembly of these components is much faster, and less costly.

[0068] Advantageously, the rotor group and the cooling pump that comprises it are of extremely compact size compared to prior art solutions: these components thus take up less space than the solutions of the prior art, thus minimising their overall dimensions in the engine compartment of the respective vehicle. Therefore, the rotor group is extremely advantageous from the point of view of saving space in the automotive sector.

[0069] A further advantageous aspect lies in the fact that many assembly operations are more reliable since not carried out by operators: for example, in the rotor group of this invention, there is no longer the step of shrink fitting or the step of insertion by interference of the impeller and/or rotor on the respective shaft.

[0070] A still further advantageous aspect consists in the fact that the rotor body of the main device is suitable to pack block the rotor, and in particular the sheet metal elements that comprise the rotor frame and inserts accommodated in the rotor body.

[0071] Advantageously, the rotor body of the main device is suitable to protect the rotor, and particularly the inserts, from external agents, for example the water that wets it, or moisture. Moreover, advantageously, the rotor body isolates the rotor from the other components including the shaft (in the embodiment in which the shaft is in turn comprised in the main device) .

[0072] A still further advantageous aspect lies in the fact that, in the embodiment with shaft not co-moulded with the other components, said shaft is suitable to maintain the rotor group aligned along its axis.

[0073] Innovatively, the production method of the rotor group is simple, since it does not require strong operator skills; in fact, the method is semi-automated.

[0074] Advantageously, the heated mould allows a slower and more controlled cooling of the fluid material injected into the mould.

[0075] Moreover, advantageously, the heated components accommodated in the mould allow a slower cooling of the fluid material injected, improving the quality of the main device.

[0076] It is clear that one skilled in the art, in order to meet contingent needs, may make changes to the pump group, all contained within the scope of protection defined by the following claims.

[0077] Moreover, each of the variants described belonging to a possible embodiment can be real independently of the other variants described.