EP0945626A2 - A fan, in particular for a cooling system of combustion engines - Google Patents

Abstract

The rotor blades are adjusted via a servo drive with an adjusting piston (11). The piston wall (12) overlaps radially with the rotor blades (2) and acts as adjusting ring to hold adjusting journals (24) of eccentric adjusters. When the piston is charged with a pressure medium, the blades are moved into a conveying direction opposite to the original conveying direction, and are loaded in a position corresponding to that direction, via air resistance force.

Description

The invention relates to a fan wheel, in particular a Cooling system of internal combustion engines usable fan wheel, according to the preamble of claim 1.

In a known fan wheel of the aforementioned type (DE-OS 28 07 899) with a cup-shaped hub are the fan blades in the Cup wall mounted and axially offset forms the hub the recording and sealing guide for one with pressure medium actable, resiliently supported in the opposite direction Control piston as control element for the fan blades. The the Adjusting eccentrics assigned to fan blades are by in the circumferential direction extending, with the fan blades inside the hub rotatably connected pivot levers formed, which over axially extending and against the piston itself supporting actuating rods are acted upon. Such Design enables relatively large piston diameters, but due to the axial offset of the piston a relatively large depth to the fan blades the hub, even with relatively small swivel angles for the fan blades, and also a relatively large one Construction effort.

In another known construction of an axial fan (DE 88 15 383 U1) is the adjusting device by a axial overlap to the air wing formed, which has a circumferential groove in which with the Fan blades non-rotatably connected, projecting radially inwards Eccentric arms each engage with a sliding block, and it is the adjusting disc via an adjusting rod with an outside the impeller hub arranged servomotor connected, so that there is also a spatially relatively complex Overall construction with many individual elements results.

In another known fan wheel construction (DE 84 06 829 U1) comes with an eccentric adjustment for the in the hub stored fan blades worked, the application of eccentric arms connected to the fan blades are, however via an adjustment plate, which is opposite with non-rotatable support the hub shell axially offset from the fan blades Area is axially displaceable via adjusting means, so that an axial adjustment of the plate to a twist the fan blade leads. The support of the eccentric arms against radial surface of the adjustment plate requires an adjustment angle for the fan blades, which are well below 90 ° and also a relatively large axial length of the hub, so that overall a relatively large volume with a corresponding Construction effort is given.

In another known solution (DE 25 52 529 A1) the fan blades of an axial fan are mounted in the fan hub, the axially offset to the wings also the electromotive Fan drive takes up. In the opposite direction to this the actuator for the fan blades is offset, which acts as an actuating means with a pressure medium Includes piston, which on a traction device on a Concentrate to the axis of rotation of the fan blades and with the Fan blades attack in a rotatably connected adjusting disc. With such a solution are large adjustment angles for the fan blades up to adjustment angles at which an opposite direction of conveyance with respect to the same direction of rotation results, possible, but the overall structure is very complex and space-intensive.

Fan wheels that can be used in cooling systems of internal combustion engines are also known from DE 4438995 A1. starting point is a motor cooling system for the known solution heavy construction machines that are used both in driving and in Stand operation can be used and where the fan wheel turns higher when driving than when stationary. Corresponding are the cooling capacities achieved via the fan wheel larger when driving than when stationary. For stand operation such an interpretation can then result in inadequate Cooling capacities result when the internal combustion engine is heavily loaded during stationary work.

To counter this, the known solution is kept constant the speed of the fan wheel its conveying direction vice versa, once towards the internal combustion engine and to promote it in the opposite direction. For this is the fan wheel inside its hub with an actuator provided, through which the blades of the fan wheel as far can be rotated so that the conveying direction is reversed, so that a forward blowing direction and a backward blowing direction can be realized in relation to the Cooling the internal combustion engine cooling performance by reversing adapt the conveying direction to the respective cooling requirement to be able to.

The invention has the design of a fan wheel type mentioned to the task, with the objective to a simple, small and flat basic structure for the fan wheel to come which allows it to be related on the direction of rotation with the same direction of rotation reversible fan wheel instead of conventional fan wheels in use existing constructions, what by the characteristics of claim 1 is achieved.

The fact that an axially displaceable adjusting piston is used finds, the function of the actuating piston is independent of the respective speed and can be based in particular on the respective size of the hub are dimensioned so that sufficiently high even at low pressures Actuating forces result. This configuration also gives the possibility of sufficient space for a simply designed, resilient return device available to provide, so that overall an adjusting device is created is that an active adjustment only in one Actuating direction, and in which the provision on the passively acting resilient resetting device takes place against the actuating force of the pressurized Actuating piston works. This enables an actuating device to be implemented, where pressurization is only in one Direction is necessary and the reversal through the feed and Switching off the pressurization is possible. Is becoming Pressurizing a pump, a compressor, or the like no additional control devices are required, but only the switching on or off of the Pump or compressor. With a view to a possible compact axial length is an axially overlapping Arrangement of control pistons and fan blades of special, independent meaning.

This leads to a pneumatic actuation in particular a very simple solution, being such a basic concept makes it possible for a normal working position of the fan wheel as the forward blowing direction corresponds to the end position approached via the resilient resetting device becomes. It is therefore not in the normal work position Pressure supply necessary so that the greatest possible occupational safety is given and also a very energy-saving Operation is only possible when pressurized approached a short-time working position as a backward blowing direction becomes. This can be done by simply switching on a pump or a compressor, especially since the large dimensioning allows working with very low pressures.

Basically, it goes without saying in the context of the invention also possible through an appropriate pressure supply Branch from pressure accumulators or another existing one To realize printing system.

Especially in connection with pneumatic actuation the actuating device can, with only a brief activation the compressed air source to build the required Signal pressure and then shutdown, time-controlled switching from the backward blowing direction as a short-time working position to the normal working position as the forward blowing direction can already be realized in that the pressure reduction time-delayed or time-controlled.

This is possible in a particularly simple manner in that the volume closed off via the control piston via a Throttle opening connected to the atmosphere, for example , with the result that the after a certain time Pressure has been reduced so far that the elastic compliant Reset device a changeover to the regular work position is possible.

The holding time of the pressure, and thus the determination of one Time period in which the so-called short-time working position is maintained is obtained before the changeover is initiated by pressure reduction can be controlled in a simple manner by both pneumatic and hydraulic Actuation that in the inlet from the work area on the throttle Check valve is arranged, for example a 2/2 way valve, that blocks the process in one switch position and in the other switching position the flow on the throttle releases.

Characterized in that the fan blades in the solution according to the invention in their respective end position via one of the actuating device independent, arbitrary towards the end position Holding force, especially those acting on the fan blades Air resistance is applied, it is connected with a prescribed, time-controlled pressure reduction possible to design the actuator so that a quasi sudden change between the two end positions not only when switching from the regular work position to the short-time working position, but also when changing over to the reverse Direction. With such an interpretation can namely via the resilient resetting device applied force in relation to the self-holding force be dimensioned so that they are only slightly larger than the self-holding power is, so that an almost complete Pressure reduction can be carried out before the change is made the change is then abrupt, because after Overcoming the self-holding force due to the pressure reduction no significant counterforce against the actuating piston is exercised. The use of those acting on the fan blades Air resistance as a holding force is a special one advantageous solution.

A switch from the regular work position to the short-time position is essentially related to the switchover time only from the capacity of the pressure source or one corresponding storage volume as a supply source.

Of course, it is also possible within the scope of the invention the backward blowing direction characterized above to maintain as a short-time job over a longer period of time, for example in that the throttle is based on the amount of compressed air supplied is adjusted so that at a slightly higher actuation pressure a state of equilibrium sets, or that in the inlet on the throttle Check valve is arranged.

The design of a fan wheel with adjustable fan blades and with in their respective end positions via one of the Actuator independent, towards the end position acting holding force also proves to be self-holding force with a view to stabilizing the fan blades in their respective end position and thus for safe operating behavior from essential, because in this way a stable end position is realizable, in which the wing is not flutter and despite the adjustability of the wings, these to the hub assume a quasi-fixed position. In addition, this can Effect realized without additional effort if the fan blades according to the invention over the opposite direction aerodynamic drag force towards each given end position are loaded.

The training of the eccentric gear with a common one Collar through the cylindrical wall part of the piston is formed, leads in connection with the radial extension and storage of the fan blades in the hub shell axial overlap to the actuating piston for a particularly simple and flat design according to the invention.

A simple structure also contributes in particular if based on the axial conveying direction of the fan wheel, the the eccentric pins assigned to the fan blades in their two, the standard work position and the short-time position corresponding end positions about the same, but preferred in the same through the axis of rotation of the fan wheel Radial plane. This results in the two end positions the same position of the fan blades, and therefore one same level of self-retention in both end positions. By appropriate Relocation of the positions corresponding to the end positions the eccentric pin it is also possible to adjust the wing positions to influence in the end positions so that these for the two working positions are not symmetrical to one Axis of rotation of the fan wheel vertical radial plane, with following the change in the corresponding self-holding forces and the flow rates.

The fan blades are - seen radially from the outside - each curved opposite to the conveying direction, so that in Cut for the fan blades one against the conveying direction Directional convex curvature results, which in the conveying direction forward end of the respective shovel one predominantly has axial extension, and that related to the direction of conveyance rearward end is largely radial Extent shows.

For the changeover between the funding directions it turns out a rotation of the wings around their respective central axis as expedient, with an angle of preferably more than 90 °, especially with an angle on the order of about 110 °, both due to the shape of the wing profile, and / or the angle of attack and / or the axial distance of the in the conveying direction at the front of the respective wing edge The axis of rotation of the fan blade is the size of the self-holding force can be influenced.

The basic concept of an air wheel with adjustable Fan blades also do it, if necessary as an additional function according to the invention while maintaining the Construction principles, possible, a speed and / or temperature dependent Adjust the cooling capacity to make the a predetermined rigid speed ratio of the crankshaft the cooling wheel increases with the speed in principle then reduce if there is a corresponding cooling capacity requirement does not exist. This is achieved with an inventive Fan wheel in that the spring-loaded Starting position of the control piston against the spring force is limited by a stop is and the stop limit speed and / or its position is changed depending on the temperature.

The starting point for this is that for a variety of purposes, especially for work machines, such as agricultural and stationary machines, as well as commercial vehicles, and here in particular agricultural vehicles like tugs the internal combustion engine mostly inside operated in a relatively narrow working area is so that for a continuous adjustment of the fan blades there is no need. The mentioned work area is usually one below the maximum speed Area of the internal combustion engine in which related to the maximum torque achievable for this range or maximum performance achievable for this area is a high, there is in particular maximum cooling power requirement. Outgoing from this area the grows with increasing speed Air flow rate and the cooling capacity achievable via this usually more than the respective maximum cooling capacity requirement. This can be achieved through the configuration according to the invention Be taken into account in which the angle of attack of the Fan blades - in the sense of a reduction in cooling capacity - is adjusted in the direction of smaller air flow, whereby this can happen directly depending on the speed.

Such a speed-dependent adjustment can be independent inventive solution can be achieved via the actuating force, those acting on the fan blades depending on the air resistance Power results, which increases with the speed, so that, based on the working area mentioned, maximum Cooling power requirement, an adjustment can be made can, in which the air resistance dependent actuating force to a resilient support is in balance. If this work area is exited upwards, i.e. the RPM increased further, so with the increased Speed a correspondingly higher air resistance dependent Positioning force, and there will be the fan blades against the elastic Support swiveled to a smaller angle of attack, where it is expedient, the allowable minimum angle of attack limit by a fixed stop.

Within the scope of the invention, but also as independently inventive Solution can be a corresponding adjustment depending on the temperature can be achieved. This is possible because a temperature-dependent stop element designed so is that there is a maximum deflection when the Internal combustion engine, with appropriate speed, in the mentioned Working area of maximum load and maximum cooling capacity requirement is working. If the speed exceeds this remains the increase in cooling capacity requirements the increase in speed, so that as a result of over the speed increasing air flow and cooling capacity Temperature drops, which leads to that being temperature dependent working stop element decreases in its deflection and an adjustment of the fan blades via the load that air resistance dependent actuating force in the direction of a smaller angle of attack and a correspondingly smaller one Air flow allows.

Thus, according to the invention, it is speed and / or temperature dependent working, created a solution through which in the critical, upper speed ranges the power requirement of the Fan wheel is taken back to the level that is used for cooling the internal combustion engine is required, so that the power loss the internal combustion engine is reduced with accordingly positive impact on the effectively available standing power of the internal combustion engine and on the Fuel consumption.

The temperature-dependent adjustability according to the invention, if appropriate also combined as temperature and speed dependent Adjustability carried out also gives the security, that in the case of a higher cooling capacity requirement in Speed range above the specified working range there is no cooling capacity deficit, as with increased Temperature and corresponding repercussions on the temperature-dependent working stop element in the fan blades above, i.e. beyond the work area mentioned adjusted speed range in their angle of attack or can be set to an angle of attack that corresponds to the maximum delivery rate if this is temperature-dependent working stop element is designed so that it also occur depending on the speed, higher depending on the air resistance Withstands actuating forces.

Springs, in particular, can be used as elastic stop elements Coil springs as temperature-dependent stop elements in particular expansion elements are used.

Fig. 1

für ein Lüfterrad gemäß der Erfindung eine Hälfte von dessen Nabe in einer schematisierten Schnittdarstellung, wobei die Schnittebene eine Radialebene durch die Lagerung eines Lüfterflügels ist, mit einer ersten Ausführungsform einer Stelleinrichtung zum Verdrehen des Lüfterflügels,

Fig. 2

eine der Figur 1 entsprechende Schnittdarstellung durch ein entsprechendes Lüfterrad bei Ausgestaltung der Stelleinrichtung in einer anderen Ausführungsform,

Fig. 3

eine schematisierte Darstellung des Lüfterrades gemäß der Erfindung in einer vereinfachten radialen Ansicht mit Darstellung des im Scheitelpunkt stehenden Lüfterflügels,

Fig. 4

eine der Figur 3 entsprechende Darstellung mit einer Stellung des Lüfterrades zur Förderung in entgegengesetzter Richtung,

Fig. 5

eine schematisierte Darstellung eines Lüfterflügels in einer der Figur 3 entsprechenden Stellung und Ausbildung,

Fig. 6

eine der Figur 2 im Grundaufbau entsprechende Darstellung, bei der die federbelastete Ausgangsstellung durch eine lageveränderliche Anschlagbegrenzung abgesichert ist, die durch elastische und/oder temperaturabhängige längenveränderliche Abstützelemente gesichert ist,

Fig. 7

eine stark schematisierte und vereinfachte Darstellung eines der Stellvorrichtung zugeordneten Stellkolbens, in der die Lage der auf den Kolben wirkenden, als elastisch nachgiebige Abstützungen eingesetzten Schraubenfeder und der in Gegenrichtung wirkenden Anschlagelemente veranschaulicht ist,

Fig. 8

eine schematisierte Darstellung des Lüfterrades ähnlich jener gemäß Figur 3 in Zuordnung zum Kühler bzw. zur Brennkraftmaschine, wobei die drehzahlabhängige überdrückte Stellung des Lüfterflügels - verringerte Kühlleistung - strichliert angedeutet ist, und

Fig. 9

eine stark schematisierte Darstellung des Frontbereiches eines Schleppers in Seitenansicht, wobei im wesentlichen auf die Anordnung der Brennkraftmaschine und des dieser zugehörigen Kühlsystems abgehoben ist.

Further refinements and features of the invention also result from the claims. Furthermore, the invention is explained in more detail with reference to the drawings. Show it:

Fig. 1

for a fan wheel according to the invention, a half of its hub in a schematic sectional view, the sectional plane being a radial plane through the mounting of a fan blade, with a first embodiment of an adjusting device for rotating the fan blade,

Fig. 2

2 shows a sectional illustration corresponding to FIG. 1 through a corresponding fan wheel when the actuating device is configured in another embodiment,

Fig. 3

2 shows a schematic illustration of the fan wheel according to the invention in a simplified radial view showing the fan blade standing at the apex,

Fig. 4

3 shows a representation corresponding to FIG. 3 with a position of the fan wheel for conveying in the opposite direction,

Fig. 5

2 shows a schematic representation of a fan blade in a position and configuration corresponding to FIG. 3,

Fig. 6

2 shows a representation corresponding to FIG. 2 in the basic structure, in which the spring-loaded initial position is secured by a position-limiting stop limitation which is secured by elastic and / or temperature-dependent length-variable supporting elements,

Fig. 7

2 shows a highly schematic and simplified illustration of an actuating piston assigned to the actuating device, in which the position of the helical spring acting on the piston as elastically flexible supports and the stop elements acting in the opposite direction is illustrated,

Fig. 8

a schematic representation of the fan wheel similar to that of Figure 3 in association with the cooler or the internal combustion engine, wherein the speed-dependent overpressed position of the fan blade - reduced cooling capacity - is indicated by dashed lines, and

Fig. 9

a highly schematic representation of the front area of a tractor in side view, with the main emphasis on the arrangement of the internal combustion engine and the cooling system associated therewith.

1 shows part of a fan wheel 1, of whose fan blades 2 only one shown with its radially inner, hub-side connecting part 3 is, the hub receiving this connector 3, which is shown schematically in section, in total with 4 is designated. The hub 4 comprises a cup-shaped hub body 5, which comprises a bottom part 6 and the cup wall 7, the cup wall serving as the peripheral wall of the hub body 5 7 via a cover 8 opposite the bottom part 6 is covered so that the hub 4 has a bottom part 6, Cup wall 7 and cover 8 has limited interior 9. At to the turning axis 10 of the hub 4, its connection to the one carrying it Wave is not shown here, concentric Structure of the hub 4, the interior 9 takes an actuating piston 11, the one adjacent to the bowl wall 7, cylindrical Piston wall 12 and a piston crown 13 comprises, piston wall 12 and piston crown 13 delimit the piston interior 14, which is open against the bottom part 6 of the hub 4. After the opposite Side borders the piston crown 13 of the actuating piston 11, in the area of the piston crown 13 via ring seals 15 is sealed against the bowl wall 7, a work space 16 from which via a supply opening 17 to a Pressure source, which is not shown here, to connect is. There is also an outflow opening 19 in the cover 8 arranged in the scope of the invention as a throttle bore is trained. The control piston is in the direction of the cover 8 11 resiliently loaded, this support in the exemplary embodiment according to FIG Coil spring 20 takes place as a support element, the diameter about the diameter of the piston interior receiving it 14 corresponds.

In the piston wall 12 axially, and also radially in overlap lying part of the bowl wall 7, the fan blades 2 are over her foot part rotatably mounted as a connecting part 3, the relevant bearings in the embodiment only schematically are indicated and designated 21. With the connector 3 is opposite to this in relation to the bearings 21 Cover part 22 non-rotatably and connected under axial tension, this in turn to the axis 23 of the bearings 21 and the respective Fan wing 2 eccentrically lying an adjusting pin 24 comprises, which in a provided in the piston wall 12 Recess 25 engages, preferably as a receiving bore, especially as the blind pin 24 leading the adjusting pin is trained.

If the working space 16 is pressurized, the Piston 11 axially displaced against the force of the spring 20, and with this shift is a pivotal movement of the Adjustment pin 24 about the bearing axis 23 with a corresponding rotation of the fan blade 2 connected about this axis, wherein the pivoting movement for the adjusting pin 24 a rotation of the Piston 11 is superimposed about the axis of rotation 10, which thereby it is necessary that with the displacement of the adjusting pin 24 the axial displacement of the piston 11 due to the eccentricity of the adjusting pin 24 to the axis 23 a corresponding Rotation of the piston must go hand in hand if there is no mechanical Blockage should occur.

The connection part is not shown in the exemplary embodiment 3 associated to cover the bearing 21, circumferential Hub cover 4.

The exemplary embodiment according to FIG. 2 corresponds to that according to Figure 1 very largely. Accordingly find for same Parts use the same reference numerals.

The actuating piston designated 31 in this exemplary embodiment are as resilient supports - support elements - But several coil springs 32 over the circumference distributed assigned, each in support against the bottom part 6 of the cup-shaped hub body in one in the back of the actuating piston 31 provided recess 33 are.

The exemplary embodiments according to FIGS. 3 and 4 show in highly schematic representation of the assignment of the fan wheel 1 to the cooler of an internal combustion engine only indicated 18, this cooler being designated 40 and being for the respective fan wheel 1 shown only one fan blade 42 is. This is the fan blade 42 that is shown in FIG View with respect to its adjustment axis of rotation 23 in one perpendicular to the plane of the drawing, the axis of rotation 10 of the fan wheel 1 containing level, so that in the bowl wall 7 provided receiving hole 43 for the storage of Connection part 3 of the respective fan blade 42 symmetrically to this level.

Starting from a position of the hub 4 corresponding to that according to Figures 1 and 2 in the configuration according to Figures 3 and 4 is the adjusting piston 11, not shown in FIG. 4 1 or 31 according to FIG. 2 in the direction of the arrow 44, so pressure-resistant away from the cooler 40, and thus counter the resilient resetting device by the spring 20 or by the springs 32 - each as support elements - is formed, slidable. A corresponding Shift causes the change of the fan blade from the Position according to Figure 3 in a position according to Figure 4. According to the situation FIG. 3 corresponds to a conveying direction of the fan wheel 1, as indicated by arrow 46 so that air through the cooler 40 is sucked in.

If the actuating piston 11 or 31 is pressurized, the result is with the axial displacement of the actuating piston 11 or 31 a rotation of the adjusting pin 24 about the respective bearing axis 23 of the associated fan blade, and therefore due the non-rotatable connection between the eccentric Adjustment pin 24 and the respective fan blades a twist of the fan blade.

Corresponding to the axially possible end positions of the actuating piston 11 or 31 there are also two end positions for the fan blades 2 of the fan wheel 1, these end positions for the fan blades 42 are shown in FIGS. 3 and 4, respectively Figure 4 shows the end position that the pressurized and shifted against the resilient support Piston corresponds. In the end position according to FIG Fan blades 42 opposite to the illustration in FIG. 3 employed, with the result that now in the direction of the Cooler 40 (arrow 47) is promoted.

The axial adjustment path of the actuating piston 11 or 31 is dimensioned that by interacting with the eccentric Adjustment pin 24 a rotation of the fan blade 42, in Embodiment results in a rotation (arrow 56) over 110 °, the fan blade 42 in its two end positions one to the plane of symmetry through the axis of rotation 23 of the fan blade 42, which is perpendicular to the axis of rotation 10 of the fan wheel 1 stands, assumes a symmetrical position. Accordingly is the delivery behavior of the fan wheel in the embodiment 1 in both conveying directions, arrows 46 and 47 the same.

The angle of rotation for the fan blades 42 can, even if a An angle of 110 ° is particularly advantageous, and an angle of 110 ° in particular with the blade configuration described proves to be particularly advantageous, especially in arched blade cross sections may also be smaller, with also angles of less than 90 °, approximately 70-90 ° according to the invention can be realized especially if in a Delivery direction a smaller delivery rate than in the other Direction is accepted, which is partly also sought can be. For example, in the context of the invention, if a particularly high output for the short-time position is sought to e.g. if the Cooler 40 to achieve a quick blow-out, for the Regulating work position required funding but comparatively is low.

Based on the embodiment shown and the one addressed The fan blades 42 are each plane of symmetry arched opposite to the respective conveying direction, whereby the curved curve 49 formed by the fan blade 42 and the chord 48 connecting the ends of the fan blades Describe a segment of a circle, its chord 48 at an angle 52 of about 50-60 °, in the exemplary embodiment about 55 ° to the to the axis of rotation 10 parallel conveying direction. Based on the axis of rotation 23 of the respective fan blade 42 and one to the chord 48 parallel, extending through the axis of rotation 23 The chord 48 and the curved curve 49 of the fan blade are currently lying 42 on different sides by the axis of rotation 23 extending straight line 50, the line given by the chord 48 Width of the fan blade essentially its radius of curvature corresponds. The center of curvature 53 for the Curved curve 49 lies on a perpendicular to the chord 48 Straight 51 through the axis 23 to which the curved curve 49 is symmetrical lies. The circumferential angle 54 of the curved curve 49 is in the embodiment between 55 and 75 °, preferred about 65 °.

The configuration of the fan blade 42 described enables for both end positions and regardless of the Position of the fan blade 42 constant direction of rotation 55 of the fan wheel 1 in a simple manner, i.e. without additional mechanical effort the realization of a self-holding effect due to the effect on the fan blade 42 Air resistance. The fan blade is in both end positions 42 through the air resistance towards the end position acted upon. Accordingly, within the scope of solution according to the invention no other special security this end position, e.g. a flapping of the wings to avoid.

A fan wheel 1 can thus be realized according to the invention, in which the actuating piston 11, 31 of the actuating device in the Forward blowing direction 46, which corresponds to the normal working position only via the resilient resetting device is loaded by the spring 20 or the springs 32 is formed. There are high preloads not necessary, as the wings 2 and 42 in this normal working position corresponding position according to Figure 3 also over the air resistance they are subjected to, so that there are no fluttering movements for the fan blades.

If the actuating piston 11 or 31 is pressurized, so is in the solution according to the invention, in which the control piston 11 or 31 is axially pressurized and one of the hub surface largely corresponding and therefore very large exposure area has only a low signal pressure required and the system can therefore be operated at low pressure operate. With the pressurization, the piston 11 or 31 against the resilient support (springs 20, 32) and the fan blades 42 reach it a position according to Figure 4, in the direction of the cooler 40 is blown (reverse blowing direction 47 or short-time working position).

If one assumes that this working position compared to the Regular work position can only be maintained for a short time is the operating time under such pressurization also shorter than the standard working hours, and the Energy consumption of such a system is lower than that of systems, those for maintaining at least one of theirs End positions each require a corresponding active application.

The pressurization is what is not shown here is, by switching on a pump or a compressor same can be done, but also by connecting to a low-pressure storage system, interrupted, so takes place Pressure reduction due to the air flowing out through the discharge opening 19, which in training as a throttle opening depending of the throttle cross-section offers a possibility of reducing pressure time-controlled.

Are the fan blades also in the direction of their short-time working position corresponding end position via the air resistance can be applied in the solution according to the invention the corresponding end position during the pressure reduction period can still be maintained because of the self-holding effect the restoring force acting on the resilient support counteracts. Appropriate coordination of this Restoring force can be assumed on the self-holding force thus a very extensive pressure reduction take place before the Changeover movement takes place, so that the changeover almost suddenly can take place, as is also the case when changing over in the opposite direction is possible under pressure.

Deviating from the schematically illustrated exemplary embodiments according to Figures 1 and 2, the throttle opening of course also elsewhere in the work room outgoing drain path can be arranged. In particular, it turns out it turns out to be useful, the throttle a check valve assign, be it upstream, downstream or in the throttle is integrated to the holding time via this valve to determine the pressure in the working chamber, and thus independently from the connection of the working chamber to the pressure source, as soon as in the Chamber of Labor for the switch to the Short-time working position required pressure is built up.

In particular in connection with such an embodiment hydraulic actuation of the control piston is advisable and advantageous, especially with hydraulic actuation in many Cases, such as with tugs on existing ones hydraulic systems and their pressure supply can be.

Especially in connection with hydraulic actuation is connected in parallel to the workspace within the scope of the invention a pressure accumulator, in particular a pressure bladder accumulator provided, such that after switching off the pressure source Maintain pressure in the work area even with certain leaks can be. Furthermore, it is also possible a choke in the drain the actual switching time also to be determined for a hydraulic system, since according to Release of the process of pressure medium from the pressure accumulator in the work area is moved up and from there via the throttle flows out, while reducing the Pressure in the pressure accumulator and working chamber System, so that the switch to the normal working position here, too, can occur almost suddenly if this System pressure has dropped to a value at which the the actuating force acting on the piston is smaller than that on the Spring-applied restoring force.

This is an actuator for a by the invention Fan wheel created the use of such a fan wheel particularly useful in the cooling system of internal combustion engines does, especially when the short-time position with reversal of the conveying direction the normal working position is to be used for the cooler, or the inflow path to the fan wheel, based on the direction of air flow in the normal work position by reversal to blow the direction of flow. See Figure 9.

Characterized in that the solution according to the invention a sudden Changeover from short-time work to regular work position enables, is the regular work of the Fan wheel and thus normal cooling operation only for a short time interrupted, which prevents overheating of the machine becomes.

The changeover to the short-time working position for cleaning purposes can depend on air resistance or other appropriate parameters, such as changes the cooling water temperature and the like take place automatically, or also manually, with only a brief one at a time Formwork of the pressure source is required to the To switch to the short-time position. Accordingly is also the energy requirement for the operation of the invention Fan wheel extremely low, especially, as explained, the reversal in the opposite direction without active Actuators is carried out.

Another embodiment of the invention is shown in FIG. 6, FIG. 6 shows a structure corresponding to that of FIG. 1 Illustration shows and use the same reference numerals Find. This also applies to the actuating piston 11 can be acted upon with pressure medium on the part of the working space 16 is and the spring loaded to its illustrated starting position is, as indicated by the coil spring 32. Deviating 1 is the actuating piston 11 starting from the work space 16 with receiving openings 75, 76 provided, which penetrates the piston crown 13 closed are executed and in which stop elements 77 and 78 are to be arranged are that are supported against the cover 8. As a stop element 77 a support spring is provided as a stop element 78 an expansion element, as may be commercially available is to be acquired. To the in the assignment to the cooler 40 or to the internal combustion engine 18 given position of the fan wheel 1 to symbolize the cooler in FIG 40 and the internal combustion engine with 18 schematically indicated.

The stop elements 77, 78 form speed or temperature dependent adjustable stop limits to which the Piston 11 in the opposite direction to the coil spring 32 as elastic resilient support element is supported, the Piston 11 has an edge 79 which, when in contact with cover 8 acts as a fixed stop.

Figure 7 shows in the schematic representation of the actuating piston 11 when viewed in the direction of arrow 80 in FIG. 6, for example, possible arrangements for the stop elements 77, 78 and those acting in the opposite direction Coil springs 32, the one shown on the left in FIG Design a radially staggered arrangement for the stop elements 77 or 78 indicates, while the right-hand side Representation of this with an arrangement offset in the circumferential direction shows. According to these instructions, it turns out to be expedient, the resilient acting from the opposite side Support symbolized by the coil spring 32, to set gap, for example in the left-hand side Representation near the piston wall, and in the right-hand side Representation close to the center. This way you can get an even one Reach the piston support from both sides of the piston, so that the piston is not subjected to tilting forces.

FIG. 8 shows, starting from a position of the hub 4 according to FIG 6, and thus based on an arrangement of the fan wheel 1 according to Figure 9, the position for a fan blade 42 in in Direction of the internal combustion engine 18 given conveying direction 46, the direction of rotation of the fan wheel 1 by the Arrow 81 is symbolized, corresponding to a direction of rotation 55.

With 42 that fan blade of the fan wheel 1 is designated, of the view shown in Figure 6 with respect to Adjustment axis of rotation 23 in a perpendicular to the drawing plane, the axis of rotation 10 of the fan wheel 1 contained level lies so that the receiving bore provided in the cup wall 7 43 for the storage 21 of the connector 3 symmetrical to this level. The fan blade 42 promotes in the 8 in the direction of arrow 46, ie in Direction to the internal combustion engine 18, and that in solid lines shown position of the fan blade 42 corresponds to a Position of the adjusting pin 24 according to FIG. 6. The adjusting pin 24 is only indicated schematically in FIG. 8. The shown Position of the fan blade 42 shown in solid lines in FIG. 8 corresponds to a maximum conveying position as the stop position, that for the piston 11 based on a predetermined Speed through the arranged in the receiving opening 76 Springs 77 is held depending on the speed, or also temperature-dependent through that arranged in receiving openings 75 Expansion elements 78. The springs 77 and / or over the expansion elements 78 as stop elements on the Piston 11 exerted a supporting force acts on the air resistance Counter force, in addition to the force of the spring 32, with the tendency to change the respective fan blades, as for the Fan blades 42 indicated by dashed lines, in a position with to press a flat angle of attack. Analogous to this Position of the fan blade 42 is also the position of the Adjusting pin 24 is shown in dashed lines in Figure 8.

Assuming that the engine 18 is a work area which is below the maximum speed and in relation to the maximum achievable for this area Torque or the maximum achievable for this area Performance a high, especially the maximum cooling capacity requirement the internal combustion engine 18 corresponding cooling power requirement is given, this corresponds to that in FIG. 8 assumed for the fan blade 42, shown in solid lines Position with a corresponding angle of attack, the based on the embodiment of Figure 8 in the order of magnitude of about 50 °. On this stop position the fan blade 42 is supported by the spring 77, the Force of the spring 77 counteracts an actuating force for the addressed work area and the given in this Speed dependent on air resistance via the fan blades 42 and the eccentric connection to the piston 11 is exerted on the piston 11 becomes. Is the piston 11 in addition in the opposite direction Spring 77 is supported by the spring 32, this must be taken into account such that the position of the fan blade 42 according to FIG. 8 quasi an equilibrium position based on corresponds to the forces addressed.

The speed of the internal combustion engine increases above the mentioned Out of range, the air resistance increases force exerted on the fan blade 42, with the effect that the spring acting as a stop element 77th is compressed and the fan blade 42 into a flatter Position pivots, as for the fan blade 42 in Figure 8 indicated by dashed lines, the for this position of the fan blade 42 given angle of attack is flatter, and this Angle of attack is assigned a position of the adjusting pin 24 as it is indicated by dashed lines This dashed layer of the adjusting pin 24 corresponds to a position, not shown of the piston 11 according to Figure 6, in which the piston 11 against the Cover 8 is present as a fixed stop over its edge 79.

A corresponds to the work area mentioned above certain cooling capacity requirements, and therefore also a certain one Temperature level to which the hub 4 is exposed. Under use a temperature-dependent expansion element as a stop element, indicated by 78 in FIG a position based on the temperature addressed of the piston 11 by appropriate deflection of the expansion element 78 reach, in terms of the description above a position of the fan blade 42 corresponds to how it is shown in full lines in FIG. 8 and in turn corresponds to a maximum cooling capacity requirement. Results a decrease in temperature, for example due to the speed-related increase in the air flow rate to unchanged angle of attack for the fan blades 42 without increasing the cooling power requirement of the internal combustion engine 18, the temperature drops, and the expansion element 78 decreases in its deflection, such that the piston 11, analogous to the compression of the spring 77 with increasing speed, moves towards the cover 8 and the Fan blades 42 in a position with a flatter stop angle swings back.

Are combined as stop elements spring-elastic stop elements (Spring 77) and temperature-dependent stop elements (Expansion element 78) used, so complete the corresponding functions and it is dependent on the temperature working, especially as an expansion element 78 trained stop element ensures that with appropriate Cooling power requirement independent of the speed via the temperature-dependent stop element Angle of attack for the fan blade 42 is controlled, which takes into account the increased cooling capacity requirement, whereby relatively small travel ranges for the respective support elements are given and needed.

FIG. 9 shows a preferred one for a fan wheel 1 according to the invention Can be used with a tractor, the tractor being designated 82 overall and has a frame part 83, the front in the area of Front axle is supported via wheels 84. In the axis area of the The front axle between the wheels 84 is the internal combustion engine 18, the cooler 40 is structurally upstream, wherein between the radiator 40 and the engine 18, the fan wheel 1, for example one according to the invention equipped fan wheel 1, which on the crankshaft of the Internal combustion engine 18 is driven in the usual way.

A lead frame 85 is provided at the front end of the frame 83, where devices or the like, for example Have it attached using a three-point lifting device.

Are such devices in particular at the front of the tractor 82 arranged, so these can be used depending on the area of work, for example as tillage equipment, harvesting machines or haymaking machines at a significant Cause pollution of the air with dust and / or plant particles, which is used as cooling air on the tractor side and over the cooler 40 from the fan wheel 1 in the direction of the internal combustion engine 18 is promoted (arrow 46). The opposite direction is symbolized by arrow 47. This air pollution can cause significant cooling problems regardless of that due to the direct drive connection of the fan wheel 1 to the crankshaft of the internal combustion engine 18, the fan wheel always the full one possible at the respective speed Cooling air volume promotes. These problems are exacerbated by as slim as possible tractor silhouettes, as desired to get the best possible overview of the work equipment to get, because from this point of view the cooler surfaces as well as the inflow surfaces to the cooler 40 if possible be kept small and therefore also in the inflow area to the cooler 40 when the cooling air is conveyed in the direction 46 to the internal combustion engine 4 high air speeds given are. The in connection with such configurations problems arising from overgrowth of the cooler 40 eliminated in the solution according to the invention in that the cooling air flow is briefly reversed and, as on the basis the cooler 40 is blown free by opposite flow.

Claims (15)

Fan wheel, in particular a fan wheel that can be used in the cooling system of internal combustion engines, with a hub and adjustable fan blades, which are rotatably guided in the peripheral wall of the hub and are adjustable via an actuator located in the cup-shaped hub, which is spring-loaded to an initial position and can be acted upon in the opposite direction by a pressure medium Control element and in its transition to the fan blades adjusting eccentric, which can be acted upon by the control element, the control element being formed by a sealing piston adjoining the bowl wall and guided over this, arranged concentrically,
characterized,
that the piston wall (12) of the actuating piston (11) as an adjusting ring for receiving adjusting pins (24) of the adjusting eccentric lies in radial overlap with the fan blades (2) and that the fan blades (2, 42) are acted upon by the actuating piston (11) with pressure medium in a conveying direction (47) opposite to the conveying direction (46) in the starting position and loaded in both of the opposing conveying directions (46, 47) in the direction of the wing position corresponding to the respective conveying direction (46 or 47). Fan wheel according to claim 1,
characterized,
that the fan blades (2, 42) are loaded in the direction of the blade position corresponding to the respective conveying direction (46 or 47) via the air resistance force. Fan wheel according to claim 1 or 2,
characterized,
that the fan blades (2, 42) are acted upon in their respective end positions via the air resistance force as a self-holding force which is independent of the actuating device and acts in the direction of their respective end position and which is smaller than the restoring force which is counteracted by the spring force against the action of the pressure medium the actuating piston (11) acts. Fan wheel according to one of claims 1 to 3,
characterized,
that, based on the axial conveying direction of the fan wheel (1), the adjusting pins (24) in both end positions corresponding to the opposite conveying directions (46 and 47) on the same side of a radial plane containing the axis of rotation (10) of the fan wheel (2, 42) lie. Fan wheel according to one of the preceding claims,
characterized,
that the fan blades (2, 42) - in a radial view - are bulged in their two end positions corresponding to the opposite conveying directions (46 or 47) opposite to the conveying direction (46 or 47). Fan wheel according to one of the preceding claims,
characterized,
that the fan blades (2, 42) between their end positions with respect to their axis of rotation (23) are rotated relative to one another by more than 90 °, in particular approximately 110 °. Fan wheel according to one of the preceding claims,
characterized,
that the fan blades (2, 42), in a radial view and in relation to the direction of rotation (55) of the fan wheel (1) are bulged against the direction of rotation (55). Fan wheel according to one of the preceding claims,
characterized,
that the fan blades (2, 42) - in a radial view and in relation to the direction of rotation (55) of the fan wheel (1) - with their rear end obliquely to the respective conveying direction (46 or 47) against the direction of rotation (55) of the fan wheel (1 ) run to the rear and with its front end essentially in the circumferential direction of the fan wheel (1). Fan wheel according to one of the preceding claims,
characterized,
that the starting position of the actuating piston (11, 31), which can be approached by the elastic support (spring 20) opposite to the adjustment direction by the application of pressure medium, corresponds to a normal operating position (conveying direction 46) and the end position of the actuating piston (11 or 31) that can be approached by the application of pressure medium a short-time position (funding direction 47). Fan wheel according to claim 9,
characterized,
that the position of the air wings (2, 42) can be switched from the short-time position (conveying direction 47) to the standard working position (conveying direction 46) by, in particular, time-controlled reduction of the pressure existing after the pressure source has been switched off. Fan wheel according to one or more of the preceding claims,
characterized,
that the spring-loaded starting position of the actuating piston (11, 31) is stop-limited against the spring force and the stop limit is speed-dependent and / or temperature-dependent. Fan wheel according to claim 11,
characterized,
that the starting position corresponds to a position of the fan blades (42) of the fan wheel (1) in which there is a high delivery capacity, in particular in the range of the maximum, and that the starting position is assigned to a working range of the internal combustion engine (18), in which one of the Maximum speed of the internal combustion engine (18) and a high cooling capacity requirement, in particular in the range of the maximum, is given. Fan wheel according to one of claims 11 or 12,
characterized,
that the stop limit is formed by the adjusting piston (11, 31) elastically resilient in the direction of the starting position loading stop elements (expansion element 27, spring 28). Fan wheel according to claim 13,
characterized,
that the support serving as limit stop is formed by at least one spring (28) and / or by at least one element made of elastic material, in particular rubber-elastic material and / or by at least one temperature-dependent length-dependent support element, in particular an expansion element. Fan wheel according to claim 13 or 14,
characterized,
that the stop elements (27, 28) serving as limit stop can be adjusted from their position corresponding to the starting position of the fan blades (1) via the fan blades, air resistance-dependent actuating force, such that the fan blades (1) are in a position as a function of the air resistance-dependent actuating force reduced delivery rate are adjustable.

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