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Title:
PUMP GROUP WITH ELECTRIC DRIVE AND MECHANICAL DRIVE
Document Type and Number:
WIPO Patent Application WO/2018/142251
Kind Code:
A1
Abstract:
A pump group (1) for a cooling system of an engine of a vehicle, comprising an impeller (2) and an impeller shaft (20), to which the impeller (2) is integrally connected. The pump group (1) comprises first of all a mechanical drive (3) and a mechanical shaft (30) rotatable by the mechanical drive (3) and secondly an electric drive (4) comprising an electric motor (40). The impeller shaft (20) is operatively connected to the mechanical shaft (30) by means of a first unidirectional clutch (51) and is connected to the electric motor (4) by means of a second unidirectional clutch (52).

Inventors:
PEDERSOLI MARCO (IT)
SURACE ALFONSO (IT)
Application Number:
IB2018/050486
Publication Date:
August 09, 2018
Filing Date:
January 26, 2018
Export Citation:
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Assignee:
IND SALERI ITALO SPA (IT)
International Classes:
F01P5/12; F04D13/02
Domestic Patent References:
WO2007079888A12007-07-19
Foreign References:
JPS60119318A1985-06-26
US3853098A1974-12-10
JP2003239852A2003-08-27
EP1911970A22008-04-16
Attorney, Agent or Firm:
GAMBA, Alessandro et al. (IT)
Download PDF:
Claims:
CLAIMS

1. Pump group (1) for a cooling system of an engine of a vehicle, comprising:

- an impeller (2) rotatable around an axis (X-X) ;

- an impeller shaft (20), which extends along the axis (X-X) and comprises an impeller end (22) to which the impeller (2) is integrally connected;

a mechanical drive (3) and a mechanical shaft (30) rotatable by the mechanical drive (3) ;

- an electric drive (4) comprising an electric motor (40) comprising a rotor (41) and a stator (42) ;

wherein the impeller shaft (20) comprises a mechanical end (23) opposite the impeller end (22) operatively connected with the mechanical shaft (30) by means of a first unidirectional clutch (51) and an electric portion (24) located between the impeller end (22) and the mechanical end (23) operatively connected to the rotor (41) by means of a second unidirectional clutch (52) .

2. Pump group (1) according to any of the preceding claims, wherein the mechanical shaft (30) extends along the axis (X-X) .

3. Pump group (1) according to any of the preceding claims, wherein the mechanical shaft (30) comprises an engagement end (32) operatively connected with the mechanical end (23) of the impeller shaft (20) by means of the first unidirectional clutch (51) .

4. Pump group (1) according to claim 3, wherein the engagement end (32) comprises a shaft housing (320) housing the mechanical end (23) and the first unidirectional clutch (51) .

5. Pump group (1) according to any of the preceding claims, wherein the first unidirectional clutch (51) is integral, or an integral part of the mechanical shaft (30) and the second unidirectional clutch (52) is integrally connected to the rotor (41) .

6. Pump group according to any of the preceding claims, wherein the first unidirectional clutch (51) comprises a rolling bearing preferably with needle rollers.

7. Pump group according to any of the preceding claims, wherein the second unidirectional clutch (52) comprises a rolling bearing preferably with needle rollers.

8. Pump group (1) according to any one of the preceding claims, wherein the mechanical drive (3) and the electric drive (4) are placed rearwards of the impeller (2) .

9. Pump group (1) according to any of the preceding claims, wherein the mechanical drive (3) comprises an electromagnetic pulley (300) mounted at a control end (33) of the mechanical shaft (30) wherein the electromagnetic pulley is normally engaged, excitable electrically to disengage the mechanical drive from the shaft .

10. Pump group (1) according to any of the preceding claims, wherein the rotor (41) comprised in the electric motor (40) is of the dry type.

11. Pump group (1) according to any of the preceding claims, further comprising a pump body (10) supporting the impeller shaft (20) and the mechanical shaft (30) respectively through a rotating bearing (161) and a mechanical bearing (162), in which the pump body (10) identifies a housing chamber (100) housing the mechanical drive (4) and said rotating bearing (161) and a mechanical bearing (162) .

12. Pump group (1) according to claim 11, wherein the housing chamber (100) is sealed tight by means of a dynamic seal (190) fitted on the impeller shaft (20) .

13. Pump group (1) according to any of the claims 10 or

11, wherein the mechanical drive (3) is mounted cantilevered on the pump body (10), presenting a portion of the mechanical shaft (30), preferably the engagement end (32), housed inside the housing chamber (100) .

14. Pump group (1) according to any of the claims from 10 to 13, further comprising an electronic control unit, suitable for controlling the electric drive (4) and/or the electromagnetic pulley (300), wherein said unit is in turn housed in said housing chamber (100) in a position proximal to the side walls thereof and extends parallel to the axis (X-X) .

Description:
DESCRIPTION

"PUMP GROUP WITH ELECTRIC DRIVE AND MECHANICAL DRIVE"

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

[0002] As is known, during the normal use of an engine, the intensity of the cooling action should be varied. For example, intense cooling is required when the engine is running at full speed or in towing conditions or on an uphill road or at high ambient temperatures. On the contrary, in other conditions of use it is advisable that the cooling is not too strong, for example when the engine is started or when at the end of the use thereof.

[0003] Cooling pumps are known in the prior art in which this need has been addressed.

[0004] In fact, cooling pumps for electrically driven vehicles are known, in which the rotation speed of the impeller is regulated by means of an electric drive and therefore the quantity of coolant which it moves in circulation in the cooling system is regulated.

[0005] Unfortunately, although these pumps are extremely versatile in their application and in the possibility of managing the rotation due to the dedicated electronic control, they typically have low output powers, limited by the electric power made available by the vehicle electrical system.

[0006] Furthermore, these pumps do not have the "fail-safe" characteristic in the event of a fault, i.e. the possibility of operating in an emergency configuration when the electric motor is broken.

[0007] Mechanically driven pumps are also known in which the rotation of the impeller is linked to the number of revolutions of the internal combustion engine; in such solutions, the regulation of the amount of coolant is entrusted to suitable regulation elements, placed upstream or downstream of the impeller, suitable for changing a section of passage of the circuit, thus varying the flow rate of coolant.

[0008] Unfortunately, while these solutions are suitable for delivering high powers thus being particularly reliable, they have less versatile cooling management, linked to the engine speed and the characteristics of the regulation element, and are typically oversized. Furthermore, in a "post-run" configuration, i.e. with the engine off, no cooling is performed.

[0009] Finally, dual actuated pumps are also known, i.e. comprising both an electric drive and a mechanical drive.

[0010] Unfortunately, these pumps have a particularly complex management of the two drives, as well as an articulated and bulky structure. [0011] The object 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 above, overcoming the above drawbacks. In other words, the object is to provide a dual drive pump group, in which the management of the two drives is simplified and is provided with a simple and compact structure.

[0012] This object is achieved by a pump group implemented according to claim 1. The dependent claims relate to preferred embodiment variants having further advantageous aspects .

[0013] The object of the present invention is described in detail hereafter, with the aid of the accompanying drawings, in which:

[0014] - figures la and lb show two perspective views with separate parts of the pump group object of the present invention, according to a possible embodiment;

[0015] - figure 2 shows a longitudinal sectional view of the pump group in figures la and lb according to a preferred embodiment.

[0016] With reference to the above tables, reference numeral 1 denotes, as a whole, a pump group for a cooling system of an engine, preferably internal combustion.

[0017] The pump group 1 object of the present invention comprises an impeller 2 which is rotatable about an axis X-X in such a way that a rotation of the impeller 2 corresponds to the movement of a predetermined quantity of coolant in the circuit.

[0018] Preferably, the impeller 2 is of the radial type, i.e., it provides that the flow of liquid at the inlet has a substantially axial overall direction and the flow of liquid at the outlet has a radial direction.

[0019] The pump group 1 has a dual drive, i.e. the impeller 2 is drivable both mechanically and electrically. For this purpose, the pump group 1 comprises a mechanical drive 3 and an electric drive 4.

[0020] Specifically, the pump group 1 comprises an impeller shaft 20 which extends along the axis X-X and on which the impeller 2 is integrally mounted, preferably at an impeller end 22 thereof; the controlled rotation of the impeller shaft 20 corresponds to the rotation of the impeller 2.

[0021] According to the present invention, the mechanical drive 3 and the electric drive 4 are operatively connected to the impeller shaft 2 to control the rotation speed thereof. As widely described below, the mechanical drive 3 and the electric drive 4 are operatively connected to the impeller shaft 2 respectively by means of a first unidirectional clutch 51 and a second unidirectional clutch 52.

[0022] According to the present invention, the impeller shaft 2 comprises a mechanical end 23 operatively connected to the mechanical drive 3, opposite the impeller end 22. In addition, the shaft comprises an electrical portion 24 located between the impeller end 22 and the mechanical end 23 operatively connected to the electric drive 4.

[0023] In particular, the pump group 1 comprises a mechanical shaft 30 rotatable by the mechanical drive 3 and operatively connected to the impeller 2, and in particular to the mechanical end 23 thereof. Preferably, said mechanical shaft 30 extends along the axis X-X.

[0024] In other words, the mechanical shaft 30 comprises an engagement end 32 operatively connected with the mechanical end 23 of the impeller shaft 20 by means of the first unidirectional clutch 51.

[0025] In a preferred embodiment, the engagement end 32 comprises a shaft housing 320 housing the mechanical end 23 and the first unidirectional clutch 51. This embodiment is extremely advantageous in a pump group configuration in which the mechanical shaft has dimensions, and in particular diameter, greater than those of the impeller shaft. However, possible solutions are contemplated in which the rotating shaft accommodates the engagement end of the mechanical shaft and the first unidirectional clutch.

[0026] In a preferred embodiment, the mechanical drive 3 comprises a pulley 300 for a transmission belt connected, for example by a kinematic chain, to the drive shaft. Preferably, the mechanical shaft 30 comprises a control end 33 opposite the engagement end 32 on which the pulley 300 is mounted.

[0027] Preferably, the pulley 300 is an electromagnetic pulley. In the embodiment with electromagnetic pulley, this is normally engaged and only when it is activated (i.e., the coil included therein is electrically energized) the release mechanism disengages the pulley from the mechanical shaft 300.

[0028] In fact, preferably, the electromagnetic pulley comprises an outer ring 301 on which the transmission belt is mounted, an inner ring 302 and an intermediate release mechanism 305 which comprises an intermediate coil. The inner ring 302 constitutes, in this embodiment, the conductive ring operatively connected to the mechanical shaft 30, which through the first unidirectional clutch 51 is operatively connected to the impeller shaft 2.

[0029] When the electromagnetic pulley is not electrically energized, the outer ring 301 is integral in rotation with the inner ring 302. On the other hand, when the electromagnetic pulley 300 is activated (i.e., the coil is electrically energized) , the release mechanism 305 disengages the outer ring 301 from the inner ring 302, so that the outer ring 301, although driven in rotation by the belt, does not transmit any rotation to the inner ring 302 and therefore to the mechanical shaft 30.

[0030] According to this preferred embodiment, the inner ring 301 is integrally connected to the mechanical shaft 30, in particular at the control end 33 thereof.

[0031] According to a preferred embodiment, the electric drive 4 comprises an electric motor 40 comprising a rotor 41 and a fixed stator 42 coaxial to the rotor 41.

[0032] Preferably, said rotor 41 is mounted on the impeller shaft 20 operatively connected to the electric portion 24 thereof through the second unidirectional clutch 52.

[0033] According to a preferred embodiment, the rotor 41 is of the dry rotor type.

[0034] According to a preferred embodiment, the first unidirectional clutch 51 comprises a rolling bearing preferably with needle rollers. For example, the rolling bearing is of the roller or needle roller type, having rolling elements arranged between the driven ring and the driving ring.

[0035] Preferably, according to a preferred embodiment, the second unidirectional clutch 52 comprises a rolling bearing preferably with needle rollers. For example, the rolling bearing is of the roller or needle roller type, having rolling elements arranged between the driven ring and the driving ring.

[0036] In a preferred embodiment of the invention, moreover, the first unidirectional clutch 51 is integral, or an integral part of the mechanical shaft 30 and the second unidirectional clutch 52 is integrally connected to the rotor 41. Preferably, therefore, the rotation of the impeller shaft 20 does not influence the rotation of the slower unidirectional clutch, i.e. the unidirectional clutch which is not transmitting the rotary motion to the shaft .

[0037] According to a preferred embodiment, the pump group 1 comprises a pump body 10 supporting the impeller shaft 20 and the mechanical shaft 30. Preferably, the pump body 10 is suitable for supporting and/or containing therein the mechanical drive 3 and the electric drive 4.

[0038] Preferably, the pump body 10 comprises an impeller chamber 120 in which the impeller 2 is housed and in which, by means of the impeller 2, the cooling liquid flows, entering through an inlet conduit 121 and exiting through an outlet conduit 122.

[0039] In addition, the pump body 10 comprises a housing chamber 100 adjacent to the impeller chamber 120 (shown schematically in figure 2), but sealingly divided thereby .

[0040] Preferably, the mechanical drive 4, i.e. the electric motor 40, is housed in the housing chamber 100. Preferably, in fact, the impeller shaft 20 extends lengthwise between the two chambers in such a way that the impeller end 22 is housed in the impeller chamber 120 while the mechanical end 23 and the electrical portion 24 are housed in the housing chamber 100.

[0041] According to a preferred embodiment, the pump body 10 comprises a dynamic seal 190 fitted on the impeller shaft 20, adapted to separate the impeller chamber 120 and the housing chamber 100.

[0042] According to a preferred embodiment, the mechanical drive 3 is mounted cantilevered on the pump body 10, presenting a portion of the mechanical shaft 30, preferably the engagement end 32, housed inside the housing chamber 100.

[0043] In a preferred embodiment, the pump body 100 comprises a rotating bearing 161 and a mechanical bearing 162, in turn housed inside the housing cavity 100, respectively operatively connected to the impeller shaft 2 and to the mechanical shaft 3 for the respective rotational support. In other words, the support of the impeller shaft 2 and of the mechanical shaft 3 is obtained by means of the above two bearings, in addition to the mutual engagement by means of the unidirectional clutch .

[0044] According to this embodiment of the pump body 10, both the mechanical drive 3 and the electric drive 4 are placed rearwards of the impeller 2.

[0045] As widely shown in the accompanying figures, the electronic control unit, suitable for controlling the electric drive 4 and/or the electromagnetic pulley 300, is in turn housed in said housing chamber 100. In particular, the electronic control unit extends lengthwise parallel to the axis X-X and is positioned in a lateral position in the pump body 10. Preferably, the electronic control unit is positioned near the side walls of the pump body 10. Preferably, the electronic control unit is insertable into the pump body 10 in a radial direction with respect to the axis X-X. Preferably, the electronic control unit, which in a preferred embodiment comprises an electronic board, is air-cooled being in a lateral position in the pump body 10. Advantageously, said position of the electronic control unit involves a minimization of the overall dimensions of the pump group 1 along the axis X-X.

[0046] Further preferred embodiments of the pump group 1 are contemplated, including a preferred embodiment in which the pump group 1 comprises a choke valve (not shown) , which is insertable into the pump body so as to be arranged along the outlet conduit from the impeller chamber 120. The valve is controllable by an actuator (not shown) , for example electric, oil-pressure or vacuum, preferably controllable by the control device. The features of this valve are illustrated in documents EP2534381, EP13188771, EP13801735, W02015/ 059586 and BS2014A000171 in the name of the Applicant.

[0047] In addition, according to yet another embodiment, the pump group 1 comprises, upstream of the impeller 2 in the inlet conduit, a regulation cartridge (not shown) suitable for regulating the amount of coolant towards the impeller. The features of said regulation cartridge are illustrated for example in document WO2015/004548 in the name of the Applicant.

[0048] According to a preferred embodiment, moreover, the pump group 1 comprises an electronic control unit for controlling the electric drive 4 and/or the electromagnetic pulley 300.

[0049] According to the embodiments described above, the electric drive 4 and/or the electromagnetic pulley 300 are electronically controlled according to the occurrence of certain conditions during use of the vehicle. [0050] For example, in a configuration in which the electromagnetic pulley is not energized and the electric drive 4 is deactivated, the impeller shaft 20 is moved only by means of the electromagnetic pulley 300, which drives in rotation the mechanical shaft 30 which operates with the impeller shaft 2 through the first unidirectional clutch 51.

[0051] In a further configuration, for example when the vehicle is started, when the engine is still cold (so- called "warm-up" configuration) , the electromagnetic pulley 300 is activated, so as to disengage its action on the mechanical shaft 30 while the electric drive 4 is left deactivated. Thus, the impeller 2 remains stationary and the liquid does not circulate in the circuit and the motor proceeds faster towards heating.

[0052] According to a further example, under high load conditions, for example when the vehicle drags a tow or faces an uphill road, typically at low speed (thus, at low engine revolutions), the electric drive 4 is activated in a manner such that the rotor 41 is rotating at a rotation speed greater than that induced by the mechanical drive 3 and by the mechanical shaft 300, thereby making the impeller shaft 20 through the second unidirectional clutch 52 rotate at the speed induced by the rotor 41. Advantageously, in this configuration, the first unidirectional clutch 51 disengages rotor 2 from the mechanical shaft 300, decreasing the masses rotated by the electric drive 4.

[0053] According to a further example, at the end of the use of the vehicle, if the coolant is still very hot, the electric drive 4 is activated so as to keep the impeller shaft 2 rotating (this phase is therefore the one called "post run") . In this way, the impeller 2 rotates at a predefined rotation speed, while the mechanical drive 3 is completely inactive, since the vehicle engine is stationary. Specifically, for example, the electromagnetic pulley is not energized, as it is not necessary to move the impeller shaft. Also in this case, the first unidirectional clutch 51 disengages rotor 2 from the mechanical shaft 300, decreasing the masses rotated by the electric drive 4.

[0054] In general, therefore, the electric drive 4 is activated whenever it is necessary to increase the cooling capacity, independently of the mechanical drive 3, constrained to the engine speed.

[0055] For example, in an embodiment in which the pump group 1 comprises a mechanical drive 3 which has a "classical pulley", of a mechanical type, therefore not electronically controllable, and the aforesaid choke valve, in the above "warm-up" step, in which the engine is still cold and it is desired to obtain a heating as fast as possible, the amount of coolant in circulation is regulated by controlling the positioning of the choke valve .

[0056] Innovatively, the pump group object of the present invention meets the engine cooling requirements and overcomes the drawbacks mentioned above.

[0057] Firstly, advantageously, the pump group according to the invention is very flexible, since it responds to the cooling needs of the vehicle according to the actual demand and not depending on the engine speed or the availability of electrical power of the system. That is to say that, advantageously, the pump group is particularly suitable for managing in its entirety the quantity of coolant in the cooling system, for example managing the cooling of further components of the vehicle in addition to the engine, such as the turbo group, obviating the need to have specific electric pumps that move the preset amounts of coolant in these components, allowing further space in the engine compartment to be gained .

[0058] Moreover, advantageously, the pump group is particularly compact and limited in size, being particularly suitable for being accommodated in the engine compartment of a motor vehicle. [0059] For example, advantageously, the impeller (and the impeller chamber with the volute) is more compact and not oversized, and operates always in conditions of optimum efficiency with respect to the known pump groups, where the impeller is often oversized to compensate for the poor flexibility of the mechanical pumps and the limited power of electric pumps.

[0060] A further advantageous aspect is that the pump group requires a limited number of dynamic seals: specifically, only a dynamic seal is required, which is necessary to divide only the impeller chamber from the housing chamber. Advantageously, the electric motor of the pump group object of the present invention can be of the dry rotor type, provided with a reduced air gap suitable for achieving a high electrical efficiency (with respect to electric motors with wet rotor) . Advantageously, therefore, the electric motor has no friction due to the presence of coolant and therefore its operation is not affected by the hydrodynamic brake effect of the coolant.

[0061] Advantageously, the dynamic seal included in the pump body is compact in dimensions having to face an action of low intensity due to frictions.

[0062] Advantageously, the design of the mechanical drive and of the electric drive is extremely simplified and optimized by the designer; advantageously, the electromagnetic pulley, if provided, does not require particular design updates; advantageously, the rotor of the electric motor is mounted directly on the impeller shaft, without requiring suitable shielded bearings, thus limiting the axial dimensions of the rotor.

[0063] Moreover, advantageously, the switching from the electric drive to the mechanical drive and vice versa is mechanically managed by the unidirectional clutches. Therefore, advantageously, the electronic management of the pump group is very simple.

[0064] Advantageously, the pump group is able to prevent the cooling action, although the engine is running, when, for example in "warm-up" conditions, it is advisable to heat the engine. In a further advantageous aspect, the pump group has the "fail-safe" feature; in fact, in the event of a failure of the electric drive, the pump group, due to the mechanical drive and the second unidirectional clutch, continues to ensure the movement of the impeller. According to a further advantageous aspect, the pump group is operative in "post-run" conditions, i.e. with the engine off. Advantageously, under "post-run" conditions, it is possible to avoid electrically energizing the electromagnetic pulley, thus saving electricity .

[0065] Furthermore, the kinematic chain between mechanical drive, electric drive and impeller is extremely simplified.

[0066] Advantageously, the first unidirectional clutch allows, in a configuration in which the impeller is rotated by the electric drive, zeroing the friction due to the mechanical part, so there are no energy absorptions, for example, of the pulley or the bearings provided therein. In addition, advantageously, the second unidirectional clutch allows, in a configuration in which the impeller is rotated by the mechanical drive, the rotor not to be driven in rotation by the shaft; therefore, magnetic friction is not produced (nor the rotor-stator assembly works as an electric generator) .

[0067] Moreover, advantageously, the first unidirectional clutch and the second unidirectional clutch are selectable with different features depending on the different actions due to the electric drive or the mechanical drive.

[0068] A further advantage lies in the fact that the first unidirectional clutch is integrable with the mechanical shaft and the second unidirectional clutch is fixable internally to the rotor, so as to avoid any dragging of the unidirectional clutch which is not in engagement by the impeller shaft.

[0069] Advantageously, the electric drive is totally independent of the dynamic seal and of the bearing which supports the mechanical shaft, thus having a greater electrical efficiency and a wider electric operating range .

[0070] Another advantageous aspect is that the mechanical shaft is supported by the pump body in such a way that all the loads, for example due to high belt loads, connected to the belt action or to the belt tension, are absorbed by the pump body and are not released onto the impeller shaft. Advantageously, the designer is free to design the impeller shaft in the dimensions, sizes and diameters he needs depending on the loads to be supported, which are mainly related to the impeller action and not to the mechanical drive. Advantageously, therefore, the impeller shaft is designable with compact dimensions, length and diameter; similarly, therefore, also the bearings that support it and the dynamic seal fitted on it are designed with compact dimensions. The presence of bearings and seal of compact dimensions (and not oversized) therefore allows the achievement of a better energy efficiency of the pump group with respect to the solutions currently known in the prior art.

[0071] It is clear that a man skilled in the art may make changes to the pump group described above in order to meet incidental needs, all falling within the scope of protection defined in the following claims. Moreover, each variant described as belonging to a possible embodiment may be implemented independently of the other variants described.