DESCRIPTION

The present invention relates to a blade for fans for cooling the cooling fluid contained in the radiator of operating machines and/or vehicles, in particular agricultural tractors and off-road vehicles, and to an apparatus for actuating and controlling the rotation of the fan blades about their axes .

It is known that the driving of operating machines and vehicles by means of a heat engine involves the need to cool the latter by means of a cooling fluid which is stored inside a cellular radiator and recirculated through the engine; the cooling fluid is in turn cooled by the ambient air which is forced to pass through the radiator by the sucking action of a rotating fan.

Taking as a reference point the normal front part of the machine/vehicle the three elements are axially arranged with the radiator at the front, engine behind it and fan arranged in between the two .

It is also known that, in the technical sector of vehicles which are generally used in conditions where there is a large quantity of loose debris, as in the case of agricultural tractors or vehicles intended for off-road use, but also operating machines which work under stationary conditions, this loose debris tends to be deposited on the cellular surfaces of the radiator containing the vehicle cooling fluid, causing blockage thereof and therefore a reduced and/or no cooling of the fluid, with consequent overheating of the engine. It is also known that the main cause of said accumulation of debris on the radiator is the forced air flow of the fan which is arranged behind the radiator in the direction of travel of the vehicle and connected to the driving shaft of the vehicle, said fan, when rotated, drawing in the air and forcing it to pass through the radiator, causing dissipation of the heat from the cooling fluid contained inside it, which is at a higher temperature, into the external environment, which is at a lower temperature.

It is also known that, under normal operating conditions, said fan must be made to rotate only when a definite predefined temperature of the cooling fluid is reached, this being detected by means of a thermostat.

In greater detail it is required that a motor vehicle fan should be able to draw air from the radiator towards the heat engine:

- in a small amount for cooling in low external temperature conditions,

- in large amounts when there are higher external temperatures or when the vehicle is used in demanding conditions resulting in overheating of the engine,

but also

- air must be temporarily forced onto the radiator in the opposite direction in order to clean it of the impurities which have accumulated during normal operation.

In order to determine these operating conditions, fan actuating apparatus able to produce controlled rotation of the fan blades from a condition for suction of the air from the radiator into a condition for propelling air onto the radiator are known, whereby in the suction condition the angle formed by the surface of the blades with the axial direction of air - below referred to as inflow angle - may be adjusted within a certain range in order to increase/decrease the flow according to the actual fluid cooling requirements.

Although these apparatus, which are mainly of the fluid-dynamic type, fulfil their function, they require however special means for supplying the fluid to the blade movement devices, said means either not always being present on the vehicles or requiring the installation of a compressor or connection pipes, which possibility, apart from increasing the costs, is not always physically feasible.

In addition, the position of the blades at the various entry angles of the blades is unstable and requires complicated auxiliary locking elements such as counterweights or the like for opposing the thrust of the air which tends to cause rotation of the blades in the opposite direction to the direction of adjustment, resulting in undesirable and noisy angular oscillations of the blades.

US 3 420 311 describes a system for fastening together blade and device for adjusting the inflow angle of the blade, which uses a double screw/female thread connection; in view of the imprecision which is always present in the design of both male and female threads, the relative rotation positions the blades in a relative angular position which is not constant and definite, resulting in differences in orientation between blades, with a consequent reduction in the efficiency and increase in the energy consumption and wear. The technical problem which is posed therefore is that of providing a blade for fans for cooling the cooling fluid in operating machines and/or vehicles, in particular vehicles such as agricultural tractors and off-road vehicles, which can be both easily and rapidly applied to a fan and can be controlled during rotation about its longitudinal axis.

In addition, it is specifically required that a definite and predetermined angular orientation of the fitted blade should be ensured so that all the blades are correctly and uniformly oriented once mounted on the fan, in order to avoid a worsening of the fluid-dynamic effects with a consequent increase in the energy consumption needed to achieve the predefined objects, both during cooling of the cooling fluid during normal operation of the machine/vehicle and during cleaning of the cells of the radiator in the event of blockage thereof.

In connection with this problem it is also required that said blade and fan should have small dimensions, be easy and inexpensive to produce, assemble and maintain and also be able to be easily installed and/or replaced on any operating machine/vehicle without the need for auxiliary devices and/or complicated connection lines and/or complex disassembly operations.

These results are achieved according to the present invention by a blade according to Claim 1 and by a fan for cooling the cooling fluid contained in the radiator of vehicles, in particular agricultural tractors and off-road vehicles, and/or operating machines according to the characteristic features of Claim 7.

Further details may be obtained from the following description of a non-limiting example of embodiment of the subject of the present invention, provided with reference to the accompanying drawings, in which :

Figure 1 : shows an exploded view of a blade according to the present invention;

Figure 2 : shows a partial vertical section through the blade of Fig. 1 in the preassembled condition; Figure 3 : shows a perspective view of the blade support hub according to the present invention;

Figure 4 : shows a partial vertical section through the hub according to Fig. 3;

Figure 5 : shows an axial vertical section through an embodiment of an apparatus for actuating and controlling rotation of the blades and the fan according to the present invention;

Figure 6 : shows a perspective view of an auxiliary device for manually actuating rotation of the blades .

As shown in Fig. 1 and assuming only for the sake of easier description and without a limiting meaning a longitudinal axis X-X corresponding to the axis of rotation of a fan 10 and a radial transverse axis Y-Y of axial extension of a blade 20 as well as - with reference to the direction of travel of a vehicle indicated by the arrow "A" in Fig. 6 - a front part corresponding to the position of a radiator 1 and a rear part corresponding to the position of the heat engine 2 of the vehicle, the fan 10 is arranged behind the radiator 1 and in front of the engine 2 and comprises a hub 111 which is preferably closed at the front by a cover 111b. The hub 111 is axially locked to a pulley 3 for rotationally driving the fan, connected by means of a suitably driven belt 3a to the shaft of the heat engine 2.

The pulley 3 is mounted on a pair of bearings 3b, 3c which are keyed onto a fixed support element, in example described consisting of a tubular sleeve 5 which is fixed to the base of the engine 2 via associated means 5a and inside which the apparatus 100 for controlling rotation of the blades 20, not described in detail, is preferably partially contained .

As shown in Figs. 1 and 2, it is envisaged that each blade 20 comprises the following pre-assembled parts :

-) a shank 21 divided into:

a first part 21a suitable for joining together with the body 20a of the blade - for example by means of overmoulding - and

a second part axially on the outside of the blade body and formed as a cylindrical pin 21b inside which at least one hole 21c with a female thread is formed; preferably a single hole 21c with female thread is present, the arrangement and function of which will become clearer below;

-) a blade flange 22 comprising

. a hollow cylindrical body 22a, the opposite end bases of which, in the transverse/radial direction Y-Y, comprise respectively:

a flat edge 22b, which is preferably polygonal and provided with through-holes 22c preferably arranged at the vertices of the polygon;

. an annular surface 22d;

-) a disk having at least one through-hole 23a which, once the blade is assembled, is coaxial with said hole 21c in the blade shank, and an annular seat 23b for seating an anti-vibration 0-ring 23c; the disk 23 has, joined thereto, an eccentric pin 24 for rotationally actuating the blade as will emerge more clearly below; the disk may be for example formed as one piece with the pin 24 or may comprise an eccentric recess for receiving the pin 24 with friction;

-) said pin 24 joined to the disk 23 extends from the latter parallel to the transverse-radial direction Y-Y of axial extension of the blade and, according to the invention, comprises external toothing 24a formed on a part of its side surface; the toothing 24a is able, during use, to mesh with corresponding teeth of a rack 71 of a device 70 for adjusting the inflow angle of the said blade 20. In addition, the eccentric pin 24 is arranged in a predefined position with respect to the hole 21c of the shank pin 21 and the corresponding hole 23a of the disk 21, so as to determine a suitable angular orientation of the blade relative to the said pin. A definite and predefined angular orientation may, for example, be obtained by means of complementary means comprising an eccentric pin 21e extending from the bottom surface of the shank 21 in the transverse-radial direction Y-Y and suitable for mating with a corresponding eccentric recess 23d in the disk 23.

-) at least one screw 25 suitable for mating with the female thread of the at least one hole 21c in the pin 21b for fixing the disk 23 to the pin 21b; - means 26 for centring the shank 21b inside the hollow cylindrical body 22a; according to preferred embodiments, said centring means may be realized in the form of a bush (Fig. 1) or roller bearing;

-) thrust bearings 27, preferably of the roller type, arranged between the disk 23 and the blade flange 22. Preferably the shank 21b is associated with a seal 21g designed to isolate from external forces the connection with the support flange 22.

As illustrated in the view of Fig. 2, fixing of the screws 25 inside the hole 21c of the shank 21b of the blade 20 causes locking of the disk 23 and relative orientation of the blade with respect to the pin 24 and, via the latter, with respect also to the hub of the fan, as will emerge more clearly below.

According to a different embodiment, a plurality (for example three) holes 21c may be present in the blade shank 21 with an eccentric position with, when the blade is assembled, a corresponding number of through-holes 23a in the disk 23 coaxial with the holes 21c in the shank and screws or pins for connecting the disk 23 to the shank 21. With this configuration one or more holes 21c may have a female thread for assembly of shank 21 and disk 23, while all the holes 21c and corresponding holes 23d in the disk 23 cooperate to obtain the definite and predefined angular orientation, forming said means for relative orientation of pin 24 and blade shank 21.

By varying the position of the orientation means 23d, 21e; 21c, 23a, 25 relative to the eccentric pin 24 it is possible to obtain a corresponding rotation of the blade which, during pre-assembly, may assume a different angular rotation which is predefined, definite and stable, following tightening of the screw (s) 25.

According to a further aspect of the invention (Figs. 4 and 5) it is also envisaged that the hub 111 which supports the blades 20 and is connected to the means for rotationally actuating the fan is formed as a single body with an internal, axially extending, through-seat 111a and radial extensions 112 with a substantially parallelepiped shape having an internal cylindrical hole 112a suitable for connection with the blade flange 22 which may thus be coaxially engaged on the hub to which it is fixed by means of screws 113 inserted inside the through-holes 22c in the flat edge 22b and screwed into corresponding female threads of holes 112c formed on the outer surface of the radial extensions 112 of the hub, against which, once assembly has been performed, the flat edge 22b of the flange 22 bears.

The axially opposite front surfaces 111 of the hub have respectively: holes llld suitable for mating with screws for fixing a front closing cover 111b on the outside and holes lllf for performing fixing to the rotor of an apparatus for actuating and controlling rotation of the fan described below. As shown in Fig. 6, the apparatus for controlling rotation of the blades 20 about their longitudinal axis Y-Y comprises an electric motor 30 which is coaxially inserted inside the tubular sleeve 5 and the shaft 31 of which is connected to an epicyclic reduction gear 40 situated axially in front of said motor .

The kinematic output element 143 of the epicyclic reduction gear is connected to a screw 50, the threading 51a of which is connected to the female thread 76b of a slider joined by means of a flange 76a to the inner support of a bearing 12, the outer support of which supports the device 70 for adjusting the inflow angle of the blades 20, described below.

The device 70 for adjusting the inflow angle of the said blades 20 is arranged between the bearing 12 for rotation of the hub and the pin 24 joined to the shank 21b of the said blades 20.

The device 70 comprises a rack 71 fixed to the bearing 12 and provided with a longitudinal toothing comprising a plurality of radial teeth suitable for meshing with the corresponding toothing 24a of the radial pin 24 integral with the disk 23 and therefore to the shank 21b of the blade 20. Preferably, the device 70 is longitudinally guided parallel to the axis X-X by lugs, not shown, arranged in the body 111, and the slider 76 is displaceable and axially guided, but rotationally fixed .

The apparatus further comprises, preferably, a sensor 90 for detecting the axial distance between the slider 76 and a reference counter-plate 75, said sensor 90 being connected to the means - not shown - for programming and controlling rotation of the blades 20.

With this configuration of blade, hub and apparatus it is possible, once the blade has been pre- assembled with the predefined angular orientation, to arrange the rack 71 of the device 70 in a substantially central position with respect to its displacement in both directions along the longitudinal axis X-X so that each blade is fixed on the hub with a first same relative orientation of all the blades with respect to the radiator, for example for cooling the fluid; then, by activating the electric motor 30 which operates the device 70, it is possible to vary simultaneously the orientation in one direction or the other of all the blades so as to optimize the efficiency of the fan, or reverse the air flow when it is required to clean the radiator.

The preferred embodiment of the single-piece hub 111 is such as to allow machining of only the seats 112a which are bored with cylindrical internal cross-section which does not have an inwardly projecting annular edge, thereby avoiding the more complex machining of both the radial and the end inner walls which join together in the axial direction the two half-parts forming the hubs according to the prior art.

This solution, in combination with the pre- assembled structure of the blade, which can be fixed to the hub as described, has the further advantage of allowing separate and independent insertion/extraction of the blades in the event of malfunctioning of one or more blades, without the need for complicated assembly operations and openings and closures in the half-parts of the entire hub.

According to a preferred embodiment it is also envisaged that the blades 20 of the fan have a radially inner part with chamfered edges - preferably symmetrical - designed to allow the rotation about the respective axis without relative interference between adjacent blades; said blades may thus rotate through angles ≥ 180°. The blade and the fan with hub according to the invention are therefore able to ensure an angular orientation which is the same for all the blades, optimizing the fluid-dynamic effects with a consequent reduction in the energy consumption needed to achieve the predefined objects, as well as rapid and low-cost manoeuvres.

Although described in connection with a number of embodiments and a number of preferred examples of embodiment of the invention, it is understood that the scope of protection of the present patent is determined solely by the claims below.