FAN WHEEL DRIVEN IN ONLY ONE ROTATIONAL DIRECTION

Abstract

A fan wheel including a fan wheel hub with fan blades supported rotatably on the fan wheel hub so as to extend radially therefrom, and a fan wheel drive accommodated in the fan wheel hub so as to be rotatable relative thereto within a limited angular range and connected to the fan blades for a corresponding rotation of the fan blades about their longitudinal axes, whereby the flow direction of the fan wheel is reversible by an inertia-based rotation of the fan wheel relative to the fan wheel drive.

Description

BACKGROUND OF THE INVENTION

The invention concerns a fan wheel which is driven in only one rotational direction with fan blades which extend radially from the fan wheel hub in which they are supported so as to be rotatable about their blade axes and are driven by the hub. The fan blades are inclined with respect to the plane of rotation of the fan wheel and their inclination is switchable via a switch-over plane extending transverse to the plane of rotation of the fan wheel so that their blade angles can be adjusted to opposite blowing directions.

Such fan wheels are generally known but are provided with expensive means for the adjustment of the inclination of the blade angle with respect to the plane of rotation of the fan wheel, in particular with respect to a switch-over of the fan blades to an opposite blowing direction through a switch-over plane extending transverse to the plane of rotation of the fan wheel.

It is the object of the present invention to provide means for simplifying this procedure with regard to the functional conditions as well as with regard to the implementation of the switch-over procedure.

SUMMARY OF THE INVENTION

A fan wheel including a fan wheel hub with fan blades supported rotatably on the fan wheel hub so as to extend radially therefrom, and a fan wheel drive accommodated in the fan wheel hub so as to be rotatable relative thereto within a limited angular range and connected to the fan blades for a corresponding rotation of the fan blades about their longitudinal axes, whereby the flow direction of the fan wheel is reversible by an inertia-based rotation of the fan wheel relative to the fan wheel drive.

In this way, caused by a speed reduction of the fan wheel drive up to an interruption of the drive, with a stop-limited free movability of the fan wheel for driving the fan blades to a switch-over plane by inertia-based mass-force dependent rotation of fan wheel and by an aerodynamic impact the fan blades can be rotated about the fan blade axes for a switch-over to the opposite blow directions of the fan wheel. The rotational or turning movements of the fan blades in the switch-over plane can in this way be initiated, supported and/or accelerated so that the switch-over of the fan blades between opposite flow direction positions of the fan blades can be achieved with very short switch-over times.

With the use of available operating capabilities the solution according to the invention can be realized without additional expenditures. This can be done in particular with common measures since controls for the drive of the fan wheels are generally anyway present and the utilization of mass forces depending on speed changes of the drive are possible without additional expenditures. The stop-limited free-wheeling movement of the fan wheel permits further an inertia-based rotation of the fan wheel: By a rapid speed reduction or interruption of the drive force or, respectively, a rapid acceleration of the drive offers the angular positions of the drive relative to the fan wheel can be changed for influencing the adjustment of the angular position of the fan blades about the blade axes for opposite blowing directions or for a correction based on aerodynamic points of view.

The possible effects on the operation of the fan wheel and on operation-dependent corrections in the mode of operation such as for example the switch-over from a suction operating mode of the fan wheel to a blowing operating mode as provided by the present invention are achieved via effects which are dependent on the adjustment of the angle of the wheel blades for opposite blowing directions while the fan wheel direction of rotation remains the same. Starting for example from a suction mode of operation, with the same direction of rotation of the fan wheel, the fan blades can be rotated about the blade axes in a neutral switch-over plane which extends normal to the plane of rotation of the fan wheel to a blowing operating mode by a decrease of the fan drive speed. With an increasing speed of the drive, the blades can be rotated about their blade axes in an opposite direction to be pivoted again to the original suction generating operating position.

In accordance with this operating sequence and the stop-limited idle movement of the fan wheel with regard to the drive, the fan wheel operation can be controlled between a suction and blow operation solely depending on a change of the drive speed. And this can be achieved almost without additional control expenditures. If necessary, this can be made dependent on desirable additional functions, such as a switch-over between suction and blowing operation based on a pressure application dependency or pressure application basis.

BRIEF DESCRIPTION OF THE DRAWINGS

Below, the fan wheel is described in particular with regard to the functional conditions with respect to a simplified basic design. Further details are explained with reference to the accompanying drawings, which show in:

FIG. 1 a front view of the fan wheel including a central, driven hub with radially extending fan blades which are inclined with regard to the plane of rotation of the blade wheel corresponding to the desired flow direction at a certain blade angle and whose rotational positions around the blade axes are stop-limited in their opposite blowing direction end positions,

FIG. 2 a schematic representation of the fan wheel in a front view of a fan blade which is inclined with regard to a plane of rotation of the fan wheel by a blade angle,

FIG. 3 a schematic and simplified cross-sectional view of the fan wheel taken along line III-III in FIG. 1, and

FIG. 4 an operating sequence representation of a fan wheel driven in only one direction for the adjustment of the radial blades which are supported in the wheel hub so as to be rotatable about their radially extending axes for obtaining opposite flow directions. For switching the flow direction from one to the opposite direction via a switch-over plane which extends normal to the plane of rotation of the fan wheel, the fan blades are rotated about their radial axes. To this end, the speed of the drive of the fan wheel is reduced or, respectively, increased whereby the fan blade is rotated by the resulting inertia-based rotation of the fan wheel with respect to the fan drive to a position in which the flow direction provided by the fan wheel is changed.

DETAILED DESCRIPTION OF A PARTICULAR EMBODIMENT OF THE INVENTION

FIGS. 1 and 3 show a fan wheel according to the invention with respect to its essential components. It is designated as a whole with the reference numeral 1. The fan wheel 1 comprises a hub 2 on the circumference thereof radially extending fan blades 3 are arranged. As shown in FIG. 3, the fan blades 3 have, at their feet, blade journals 4 via which they are supported in the hub 2 so as to be rotatable about their radial blade axes 5. In this way, they are each adjustable to generate flows in opposite directions by a rotation over a switch-over plane 9 forming a neutral plane n which extends normal to the plane of rotation 6 of the fan wheel 1. The direction of rotation of the fan wheel 1 is indicated in FIG. 2 by the reference numeral 19. The, in accordance with the blade angle 7 forward-facing, front side of the fan blade 5 is designated by the numeral 21.

The interior 8 of the hub accommodates the drive 10 of the blade wheel 1, preferably an electric motor, arranged so as to support the hub 2. The drive 10 is rotatable about its axis 17 relative to the hub 2 within limits formed by stops. The hub 2 includes a cover part 13 which corresponds to a base part 14 surrounding the drive 10 radially in the area of the blade journals 4. The cover part 13 is provided with the stops in the form of pin-like elements 11 arranged opposite the drive 10 that is facing the drive 10 and extending into guide slots 12 formed in the drive 10 and limiting the range of rotation of the drive 10 relative to the hub 2 in which the drive 10 is accommodated. The drive 10 is provided, preferably at its front side facing the cover part 13, with an annular gear ring 15 which is in engagement with pinions 16 provided on the foot end journals 4 so as to form a drive connection of the drive 10 with the fan blades 3. The use of cam- and/or eccentric drives is also possible in connection with the invention, not shown in the drawings.

With the stop-limited rotatability of the hub 2 with respect to the drive 10, the fan blades 3 can be transposed via the switch-over plane 9 so as to blow in opposite flow directions while the direction of rotation 19 of the fan wheel 1 remains the same. As shown in FIG. 4 the fan wheel 1 can therefore be operated in a suction or a blowing mode, that is, for example in a suction cooling mode or in a blowing cleaning mode of operation simply by pivoting the fan blades 3 through the switch-over plane 9 to the respective opposite blowing direction. Hereby, the fan blades 3 are in each case so oriented that the same front blade side 21 faces the incoming air so that the same operating conditions are provided for the suction and the blowing operation.

In accordance with the present invention the switch-over of the fan blades 3 is initiated by a rapid reduction of the speed of the drive 10. With this speed reduction and a correspondingly reduced aerodynamic air impact on the fan blades 3, the inertia force of the fan wheel causes the switch-over via the switch-over plane 9 of the blades 3. The switch-over plane 9 is shown in the operating sequence representation of FIG. 4 as an area delimited by dashed lines in which a rapid speed reduction of the drive 10 occurs by the interruption of the drive 10 resulting in the inertia-based rotation of the fan wheel corresponding to the adjustment range of the fan blades 3.

In accordance with the switch-over of the fan blades 3 in the area of the switch-over plane 9 from a suction operation assumed to be a normal operation—indicated in FIG. 4 by the numeral 22—to a blow operation—indicated in FIG. 4 by the reference numeral 23—has been established after passage through the switch-over plane 9. If such a switch-over is performed for example for cleaning purposes this may be in particular a short-period operation. In other applications it may be for longer operations. In any case, the fan wheel can again be returned to the normal operation 22 assumed to be the suction operation as shown in FIG. 4 again dependent on the drive speed. To this end, however, the previous procedure is reversed in that the speed is increased, in particular rapidly increased, which results in a switch-over of the fan blades 3 via the switch-over plane 9 to a suction operation.

Such reversibility of the fan wheel 1 with respect to the flow direction can also be combined with a possibility to adjust the blade angle 7 of the fan blade 3 with respect to the amount of air moved by the fan wheel which would provide for further application possibilities.

Concerning the different application possibilities for the fan wheel it may be expedient to vary the stop-limited rotation range of the fan wheel hub 2 with respect to the drive 10. The drive 10 can be rotatable relative to the fan wheel hub 2 within elastic stop limits, for example, dependent on thermal set values using thermo elements, shape memory materials or similar. In this respect, it may also be expedient to change the rotational position of the annular gear ring 15 in the drive train of the drive 10 and/or to the hub 2.

As a result, with the present invention a fan wheel 1 is provided which is rotatable only in one direction but whose fan blades 3 are rotatable about the radial fan blade axes 5 in a switch-over plane 9 which extends normal to the plane of rotation 6 of the fan blades 3 by an inertia-based rotation of the fan wheel 1 with respect to the fan drive 10 and by an aerodynamic impact on the fan blades 3 to move the air in an opposite directions.

LISTING OF REFERENCE NUMERALS

• 1 fan wheel
• 2 hub
• 3 fan blade
• 4 blade journal
• 5 radial blade axis
• 6 plane of rotation
• 7 blade angle
• 8 interior of hub
• 9 switch-over plane
• 10 drive
• 11 pin-like stop elements
• 12 guide slot
• 13 cover part
• 14 base part
• 15 annular gear ring
• 16 pinion
• 17 drive axis
• 19 direction of rotation
• 21 forward facing front side
• 22 suction operation
• 23 blow operation
• n neutral plane

Claims

1. In a fan wheel (1) driven in only one direction of rotation, comprising a fan wheel hub (2) rotatable relative to a fan wheel drive (10) in a stop-limited manner and having fan blades (3) extending radially from the hub (2) of the fan wheel (1) and being supported by the fan wheel hub (2) so as to be rotatable about the blade axes (5) with a blade angle (7) which is inclined relative to a plane of rotation (6) of the fan wheel (1) and which is adjustable via a switch-over plane (9) which extends transverse to the plane of rotation (6) of the fan wheel (1) to provide for an opposite direction of the flow generated by the fan wheel (1), wherein the blade angle (7) relative to the switch-over plane (9) is adjustable by a reduction of the drive speed of the fan wheel (1) resulting in an inertia-based rotation of the fan wheel (1),the fan blades (3) are switched to opposite flow directions by an aerodynamic force application, andin the area of the switch-over plane (9), the fan blades (3) can be switched between the opposite direction flow generating positions by a rapid speed reduction of the drive (10) of the fan wheel (1) resulting in an over-running inertia based rotation of the fan wheel (1) and, respectively, by a rapid increase of the speed of the drive (10) with respect to the speed of the fan wheel (1).

2. A fan wheel (1) driven in only one direction of rotation according to claim 1, characterized in that the drive (10) is rotatable relative to the fan wheel hub (2) within elastic stop limits.

3. A fan wheel (1) driven in only one direction of rotation according to claim 1, characterized in that the drive (10) is rotatable relative to the fan wheel hub (2) within stop limits by at least one thermo element.

4. The fan wheel (1) driven in only one direction of rotation according to claim 1, characterized in that the fan wheel hub (2) includes a cover part (13) including pin-like stop elements (11) extending cover part (13) operatively arranged facing the drive (10), the drive (10) having guide slots (12) arranged for receiving the pin-like stop elements (11), wherein a range of rotation of the hub (2) about a drive axis (17) of the drive (10) is limited by the pin-like stop elements (11) within the guide slots (12).