"PUMP GROUP WITH ELECTRIC DRIVE AND MECHANICAL DRIVE ON

THE IMPELLER"

[0001] The present invention relates to a pump group for a cooling system of a vehicle, preferably for cooling an engine, such as an internal combustion engine.

[0002] As is known, during normal use of an engine, it is appropriate to vary the intensity of the cooling action.

[0003] For example, an intense cooling is appropriate when the engine is working at full capacity or in towing conditions or on an uphill road or with high ambient temperatures .

[0004] In other conditions of use instead, it is appropriate for the cooling not to be accentuated, for example when starting the engine or after use.

[0005] The prior art discloses cooling pumps in which this need has been addressed.

[0006] Cooling pumps are in fact known of for electrically operated vehicles, in which the speed of rotation of the impeller is regulated by means of an electric drive and thus the amount of coolant moved by it in circulation in the cooling circuit.

[0007] Unfortunately, such pumps, although extremely versatile in their application and in the possibilities of rotation management thanks to the dedicated electronic control, typically have low delivery power, limited by the electric power provided by the vehicle's electrical system .

[0008] Furthermore, these pumps do not have the "fail-safe" feature in case of failure, i.e. the possibility to function in an emergency configuration when the electric motor has suffered a breakage.

[0009] Mechanically operated pumps are also known of where the rotation of the impeller is related to the number of revolutions of the internal combustion engine; in these solutions, the adjustment of the quantity of coolant is entrusted to special adjustment elements, placed upstream or downstream of the impeller, suitable to change the through cross-section of the circuit thus varying the flow of coolant liquid.

[0010] Unfortunately, such solutions although suitable for delivering high power and proving conspicuously reliable, have less versatile cooling management, related to the engine speed and the characteristics of the adjustment element, and are typically oversize. Also, in a "post-run" configuration, i.e. with the engine off, no cooling is performed .

[0011] Lastly, dual drive pumps are also known of, i.e. comprising both an electric drive and a mechanical drive.

[0012] Unfortunately, these pumps have particularly complex management of the two drives, as well as an articulated and bulky structure.

[0013] The purpose of the present invention is to provide a pump group for a cooling system of a vehicle, for example for an internal combustion engine, which meets the requirements mentioned, overcoming the drawbacks spoken of. In other words, the aim is to provide a dual action pump group, with simplified management of the two drives, and with a simple and compact structure.

[0014] Such purpose is achieved by a pump group made according to claim 1. The dependent claims refer to preferred embodiment variants having further advantageous aspects .

[0015] The object of the present invention will be described in detail below, with the help of the appended drawings, wherein :

[0016] - figures la and lb shows two perspective views of the pump group according to the present invention, according to a possible embodiment;

[0017] -figure 2 shows a longitudinal cross-section view of the pump group referred to in figures la and lb, according to a first embodiment variant;

[0018] -figure 2 ' shows an enlarged cross-section view of a detail of the pump group shown in figure 2;

[0019] -figure 3 shows a longitudinal cross-section view of the pump group referred to in figures la and lb, according to a second embodiment variant;

[0020] -figure 3' shows an enlarged cross-section view of a detail of the pump group shown in figure 3;

[0021] -figure 4 ' shows an enlarged cross-section view of a detail of the pump group referred to in figures la and lb, according to a further embodiment;

[0022] - figure 5a shows a perspective view of the pump group according to the present invention, according to a further embodiment;

[0023] - figures 6a and 6b show two longitudinal cross- section views of the pump group in figure 5a;

[0024] -figure 6' shows an enlarged cross-section view of a detail of the pump group shown in figures 6a and 6b;

[0025] -figure 6" shows an enlarged cross-section view of a detail of the pump group in the embodiment analogous to that of figures 6a and lb, in a further embodiment variant.

[0026] With reference to the aforementioned drawings, reference numeral 1 globally denotes a pump group for a cooling system of an engine, preferably an internal combustion engine.

[0027] The pump group 1 of the present invention comprises an impeller 2 rotatable around an axis X-X so that the rotation of the impeller 2 corresponds to the movement of a predetermined quantity of coolant in the circuit. [0028] Preferably, the impeller 2 is of the radial type, i.e. provides that the incoming flow of liquid has an overall substantially axial direction and the flow of liquid in output has a radial direction.

[0029] The pump group 1 provides a dual drive, i.e. it is operable both mechanically and electrically. To such purpose, the pump group 1 comprises a mechanical drive 3 and an electric drive 4.

[0030] In particular, the pump group 1 comprises a mechanical shaft 300 rotatable by the mechanical drive 3 and operationally connected to the impeller 2.

[0031] In a preferred embodiment, the mechanical drive 3 comprises a pulley 33 for a drive belt connected, for example by using a kinematic chain, to the drive shaft.

[0032] Preferably, the pulley 33 is an electromagnetic pulley. In the embodiment with the electromagnetic pulley, this is normally engaged and only when it is actuated (i.e. the coil in it is electrically excited) does the release mechanism disengage the pulley from the mechanical shaft 300.

[0033] In fact, preferably, the electromagnetic pulley comprises an outer ring on which the drive belt is mounted, an inner ring and an intermediate release mechanism which comprises an intermediate coil. The inner ring is, in this embodiment, the drive ring operationally connected to the mechanical shaft 300, which by means of a first unidirectional clutch 51 (described below) is operatively connected to the impeller 2.

[0034] Normally, i.e. when the electromagnetic pulley is not electrically energized, the outer ring is integral in rotation with the inner ring. In this configuration of the electromagnetic pulley disabled, if the inner ring has a rotation speed greater than the driven ring, the mechanical shaft 300 is dragged in rotation mechanically. Instead, when the electromagnetic pulley is activated (i.e. the coil is electrically energised) the release mechanism releases the outer ring from the inner ring, so that the outer ring, while driven in rotation by the belt, does not transmit any rotation to the inner ring and thus to the mechanical shaft 300.

[0035] In addition, the pump group 1 comprises an electric shaft 400 rotatable by the electric drive 4 and operationally connected to the impeller 2.

[0036] Preferably, the electric drive 4 comprises an electric motor 40 comprising a rotor 41 mounted on an impeller portion 401 of the electric shaft 400 and a stator 42 fixed coaxial to the rotor 41.

[0037] According to a preferred embodiment, the rotor 41 is of the wet rotor type.

[0038] The pump unit 1 further comprises an electronic control unit 45 to control the electric drive 4 and/or electromagnetic pulley.

[0039] According to a preferred embodiment, the pump group 1 comprises a pump body 10 to support and contain the various components described previously and described below comprised in the pump group 1. Preferably, the pump body 10 is suitable to allow the fluidic connection with the cooling system and is suitable to be flanged or connected to other vehicle components such as the engine.

[0040] The pump body 10 comprises a main casing 12 housing the impeller 2 in an impeller chamber 120, in which the coolant enters through an inlet duct 121 and exits through an outlet duct 122, preferably entering in an axial direction and exiting in a radial direction.

[0041] Preferably, the pump body 10 comprises, also, a mechanical drive casing 13 for the support of the mechanical drive 3, suitable to support the mechanical shaft 300 preferably by means of special rotation means 135, such as bearings. In a preferred embodiment, the mechanical drive casing 13 is separated from the impeller chamber 120 by means of a dynamic seal 6.

[0042] Preferably, the pump body 10 further comprises an electric drive casing 14 for the support of the electric drive 4, suitable to support the electric shaft 400 in rotation, and to contain the electric motor 40. [0043] Preferably, the electric drive casing 14 is fluidically connected with said impeller chamber 120. Specifically, the electric drive casing 14 comprises a rotor chamber 140, which extends along the axis of the electric shaft 400, containing the rotor 41 which is fluidically connected with the impeller chamber 120.

[0044] Moreover, in a preferred embodiment, the pump body 10 comprises a control casing 15 placed on the electric drive casing 14 containing, sealed with respect to the coolant, the electronic control unit 45. Said control casing 15 is placed at the opposite end with respect to the impeller 2.

[0045] As mentioned, the mechanical shaft 300 and electric shaft 400 are both operatively connected with the impeller 2 to control the rotation speed thereof.

[0046] Preferably, the mechanical shaft 300 and electric shaft 400 extend along the axis X-X.

[0047] In a preferred embodiment, the mechanical shaft 300 and electric shaft 400 extend in two opposite directions, at the two sides of the impeller 2.

[0048] Preferably, the mechanical drive 3 is placed behind the impeller 2 while the electric drive 4 is placed in front of the impeller 2; similarly, the respective casings comprised in the pump body 10 are respectively positioned behind and in front of the impeller casing 12 (by way of a non-limiting example as shown in the embodiment in figures 2, 3 and 4) .

[0049] In a further preferred embodiment, the mechanical shaft 300 and the electric shaft 400 extend in the same direction as the impeller 2, one concentric with the other (as, instead, shown by way of a non-limiting example, in the embodiments of figures 5 and 6) .

[0050] Preferably, both the mechanical drive 3 and the electric drive 4 are placed behind the impeller 2; similarly, the respective casings comprised in the pump body 10 are also respectively positioned behind the impeller casing 12: the electric drive casing 14 is present centrally along the axis X-X with the rotor chamber 140 fluidly connected with the impeller chamber 120, while the mechanical drive casing 13 extends concentrically to the axis X-X separated from the impeller chamber 120 by means of a dynamic seal 6.

[0051] Preferably, the rotor chamber 140 is fluidically connected with the impeller chamber 120, preferably being adjacent with each other. In some embodiment variants, the rotor chamber 140 is fluidically associated with the impeller chamber 120 through the electric shaft 400 and/or through special channels 210, for example made through the impeller or made through the casings.

[0052] In further embodiment variants (not shown) both the mechanical drive 3 and the electric drive 4 are placed in front of the impeller 2; similarly, the respective casings comprised in the pump body 10 are also respectively positioned in front of the impeller casing 12.

[0053] The mechanical shaft 300 and the electric shaft 400 comprise a mechanical shaft impeller end 302 and an electric shaft impeller end 402 operatively connected to the impeller 2 respectively by means of a first unidirectional clutch 51 and a second unidirectional clutch 52.

[0054] In other words, between the mechanical shaft 300 and the impeller 2 a first unidirectional clutch 51 is interposed, while between the electric drive and impeller a second unidirectional clutch 52 is placed.

[0055] According to a preferred embodiment, the impeller 2 comprises a central hub 20, arranged on the axis X-X, on which the first unidirectional clutch 51 and the second unidirectional clutch 52 are housed. In addition, the impeller 2 comprises a blade portion 21 having a radial extension from the central hub 20. In one embodiment, the central hub 20 is integral with the blade portion 21; in other embodiments the central hub 20 and the blade portion 21 are two, distinct, mutually mounted elements.

[0056] Preferably the first unidirectional clutch 51 and the second unidirectional clutch 52 are co-moulded with the impeller 2, preferably they are co-moulded with the central hub 20.

[0057] According to a preferred embodiment, the first unidirectional clutch 51 comprises a rolling bearing for the support in rotation of the mechanical shaft impeller end 302. For example, the rolling bearing is of the type with rollers or needle rollers, having rolling elements placed between the driven ring and the drive ring.

[0058] According to a preferred embodiment, the second unidirectional clutch 52 comprises a rolling bearing for the support in rotation of the electric shaft impeller end 402. For example, the rolling bearing is of the type with rollers or needle rollers, having rolling elements placed between the driven ring and the drive ring.

[0059] In a preferred embodiment, the first unidirectional clutch 51 and the second unidirectional clutch 52 are arranged side by side along the axis X-X.

[0060] In a further preferred embodiment, the first unidirectional clutch 51 and the second unidirectional clutch 52 are arranged one concentric to the other. Preferably, in this embodiment, the first unidirectional clutch 51 and the second unidirectional clutch 52 are axially, parallel to the axis X-X, superposed for at least a portion.

Depending on the type and arrangement of the unidirectional clutches, the central hub 20 is specially shaped to be operatively connected to the impeller end of the mechanical shaft 300 and/or electric shaft 400, in order to support and/or house said clutches and the respective impeller of the electric shaft and of the mechanical shaft. That is to say, the central hub 20 is specially shaped to house and/or support the respective clutches in such a way that they are facing inwards and/or outwards. According to a preferred embodiment, the central hub 20 is compact in size, i.e. extends in length along the axis X-X by a portion substantially equal, or slightly greater than the height of the blade portion 21, (as shown in figures 2 and 3) ; in other preferred embodiments, the central hub 20 is also suitable to extend in length along the axis X-X by a longer portion, proving two or three times greater than the previously described embodiment. In some preferred embodiments, the central hub 20 comprises a through cavity along the axis X-X; in other preferred embodiments, the central hub 20 comprises two respective cavities made at the axial ends.

[0061] Preferably, in a similar embodiment to that shown in figure 3, the mechanical shaft impeller end 302 comprises a pin 302' that extends along the axis X-X, while the electric shaft impeller end 402 comprises a housing 402' suitable to house and rotationally support the pin 302' .

[0062] Instead, in an embodiment variant (not shown) the electric shaft impeller end 402 comprises a pin which extends along the axis X-X, while the mechanical shaft impeller end 302 comprises a housing suitable to house and rotationally support the pin.

[0063] According to a preferred embodiment, said pin is housed in the respective housing comprising a bushing suitable to limit the friction between the two shafts.

[0064] A further aspect of the pump group 1 according to a preferred embodiment is related to the fact that the electric shaft 400 has inside it a central duct 450 that extends in length along the axis X-X; preferably, the central duct 450 has, near its ends, radial access mouths 450' . In other words, thanks to the central duct 450, the coolant that fills the rotor chamber 140 also flows inside the electric shaft 400 through the central duct 450. Preferably, the impeller 2 in rotation also aspirates, in addition to the coolant present in the impeller chamber 120, the coolant through the central duct 450 present in the rotor chamber 140.

[0065] Further preferred embodiments of the pump group 1 exist, including a preferred embodiment in which the pump group 1 comprises a choke valve (not shown) , housed in the pump body so as to be placed along the outlet duct 122 from the impeller chamber 120. The valve is controllable using an actuator (not shown) , for example electric, hydraulic or vacuum, preferably controllable by the control device. The characteristics of such valve are disclosed in the documents EP2534381, EP13188771, EP13801735, W02015 / 059586 and BS2014A000171 on behalf of the Applicant.

[0066] In addition, according to yet another embodiment, the pump group 1 comprises, upstream of the impeller 2 in the inlet pipe 121, an adjustment cartridge (not shown) suitable to adjust the amount of coolant flowing towards the impeller. The characteristics of said obturator cartridge are illustrated for example in the document WO2015/004548 on behalf of the Applicant.

[0067] According to the embodiments described above, the electric drive 4 and/or possible electromagnetic pulley are controlled electronically depending on the occurrence of certain conditions during use of the vehicle.

[0068] In a normal configuration, the electromagnetic pulley is not energised and the electric drive 4 is off, so the impeller 2 is moved only by the electromagnetic pulley, i.e. by the rotation of the mechanical shaft 300.

[0069] For example, when starting the vehicle, if the engine is still cold (so-called "warm-up" configuration), the electromagnetic pulley is activated in order to disengage the action on the mechanical shaft 300 while the electric drive 4 is left off. As a result the impeller 2 remains stationary, the liquid does not circulate in the circuit and the motor warms up faster.

[0070] According to another example, under heavy load conditions, such as when the vehicle is towing a trailer or going uphill, typically at low speed (and therefore with low engine revs), the electric drive 4 is activated in order to place the electric shaft 400 in rotation at a speed greater than that induced by the mechanical drive 3 and by the mechanical shaft 300, thus inducing the impeller 2 to rotate at the speed induced by the electric shaft 400.

[0071] Advantageously, in this configuration, the first unidirectional clutch 51 disengages the impeller 2 in rotation from the mechanical shaft 300, reducing the masses dragged in rotation by the electric drive 4.

[0072] According to a further example, after use of the vehicle, if the coolant is still very hot, the electric drive 4 is activated so as to keep the impeller 2 rotating (this stage is called "post run") . This way, the impeller 2 rotates at a predetermined rotation speed, while the mechanical drive 3 is completely inactive, since the vehicle engine is off. Specifically, for example, the electromagnetic pulley is not energized, it not being necessary for the movement of the rotation shaft. In this case too, the first unidirectional clutch 51 disengages the impeller 2 in rotation from the mechanical shaft 300 reducing the masses dragged in rotation by the electric drive 4.

[0073] In general, therefore, the electric drive 4 is activated whenever it is necessary to increase the cooling capacity, regardless of the mechanical drive 3, related to the engine speed.

[0074] For example, in an embodiment in which the pump group 1 comprises a mechanical drive 3 with a "classic pulley" of the mechanical type, therefore not controlled electronically and the above-mentioned choke valve in the aforementioned "warm-up" phase in which the engine is still cold and heating as fast as possible is desired, the quantity of coolant in circulation is regulated by controlling the positioning of the choke valve.

[0075] Innovatively, the pump group according to the present invention satisfies the cooling requirements of the engine and overcomes the drawbacks referred to above.

[0076] In the first place, advantageously, the pump group according to the invention is very flexible, as it responds to the cooling needs of the vehicle depending on actual demand and not on the engine speed or availability of electric power of the system. That is to say, advantageously, the pump group proves particularly suitable for entirely managing the quantity of coolant in the cooling system, for example by managing the cooling of further vehicle components besides the engine, such as the turbo group, obviating the need to have specific electrical pumps to move the predetermined quantities of coolant in such components, permitting extra space to be gained in the engine compartment .

[0077] Moreover, advantageously, the pump group is particularly compact and small in dimensions, making it particularly suitable to be housed in the engine compartment of a motor vehicle.

[0078] For example, advantageously, the impeller (and the impeller chamber with the volute) is more compact and not oversized, and always operates in optimal performance conditions compared to the known pump groups, where the impeller is often oversized to compensate for the poor flexibility of the mechanical pumps and limited power of the electric pumps.

[0079] A further advantageous aspect lies in the fact that the engagement of an electric drive and a mechanical drive directly on the impeller, for example without intermediate shafts, simplifies the structure of the pump group, which is more compact in size compared to solutions of the prior art .

[0080] Yet a further advantageous aspect consists of the fact that the pump group requires a small number of dynamic seals: specifically only one dynamic seal is needed to divide the impeller casing from the mechanical drive casing. Advantageously, the electric motor of the pump group of the present invention may be provided with a wet rotor type, therefore not needing specific dynamic seals, instead needed to sealingly isolate it from the coolant liquid .

[0081] Advantageously, the design of the mechanical drive and of the electric drive is extremely simplified and optimisable by the designer; advantageously, the electromagnetic pulley, if provided, does not require special design updates; advantageously, the rotor of the electric motor is mounted directly on the impeller shaft, without the need for special shielded bearings, thus limiting the axial footprint of the rotor.

[0082] Moreover, advantageously, the transition from the electric drive to the mechanical drive and vice versa is operated mechanically by the unidirectional clutches. Therefore, advantageously, the electronic management of the pump group is very simple.

[0083] Advantageously, the pump group is able to avoid the cooling action, even though the engine is in gear, when for example, in conditions of "warm-up", it is appropriate to heat the motor.

[0084] In a further advantageous aspect, the pump group has the "fail-safe" characteristic; in fact, in the event of a failure of the electric drive the pump group, thanks to the mechanical drive and the second unidirectional clutch, continues to ensure the movement of the impeller.

[0085] According to a further advantageous aspect, the pump group is operative in "after-run" conditions, i.e. with the engine off. Advantageously, in conditions of "post- run", it is possible to avoid electrically powering the electromagnetic pulley, saving electricity.

[0086] A further advantageous aspect consists in the fact that the pump group has a more limited power absorption compared to standard mechanical pumps.

[0087] Advantageously, the impeller is producible already comprising the unidirectional clutches, in fact, inserted in it, in its moulding operations.

[0088] Moreover, the kinematic chain between the mechanical drive, electric drive and impeller is extremely simplified .

[0089] In addition, advantageously, the second unidirectional clutch allows the rotor, in a configuration in which the impeller is made to rotate by the mechanical drive, not to be rotated by the shaft; magnetic friction is thus not produced (nor does the rotor-stator group work as an electric generator) .

[0090] Moreover, advantageously, the first unidirectional clutch and the second unidirectional clutch are selectable for different characteristics as a function of the different actions required of the electric drive and the mechanical drive.

[0091] Advantageously, the electric drive is totally free of the dynamic seal and of the bearing supporting the drive shaft, thus presenting greater electrical efficiency and a wider range of electrical operation.

[0092] A further advantageous aspect also lies in the versatility of design of the pump group, and in particular of the respective casings, which are designable as needed in such a way as to house and/or support the electric drive and the mechanical drive, in such a way that the respective shafts are operatively connected to the impeller.

[0093] Yet a further advantageous aspect consists in the fact that the water chamber in which the rotor of the electric motor is housed is efficiently filled by the coolant thanks to the electric shaft which it is mounted on which allows an efficient recirculation of coolant, aspirating it through the central duct.

[0094] It is clear that a person skilled in the art may make modifications to the pump group described above so as to satisfy contingent requirements, all contained within the scope of protection as defined by the following claims.

[0095] In addition, each variant described as belonging to a possible embodiment may be realised independently of the other embodiments described.