WO2014056467A1

WO2014056467A1 - Protective grid for fan comprising twisted rods having a polygonal cross-section for reducing karman vortex separation noise

Info

Publication number: WO2014056467A1
Application number: PCT/DE2013/000438
Authority: WO
Inventors: Uwe Stadtmüller
Original assignee: Uwe Stadtmüller
Priority date: 2012-10-11
Filing date: 2013-08-06
Publication date: 2014-04-17
Also published as: EP2906832A1; HUE050270T2; EP2906832B1; DE102012020245A1; DE102012020245B4

Abstract

The invention relates to a protective device (1), in particular for a ventilation system, comprising at least one protective element (3) that has an elongated, twisted profile (9) having a polygonal cross-section or is a round tube, wherein the geometric configuration of the protective element considerably reduces the installed mass, such that a weight reduction is achieved owing to saving of material.

Description

FENDER PROTECTION GRILLE WITH DRILLED BARS WITH POLYGONAL CROSS SECTION FOR REDUCING KARMAN SPRINKLER NOISE

State of the art

The invention relates to a protective device, according to the preamble of claim 1.

Safety devices which are used in particular for ventilation systems are often made of concentrically arranged around a center protection elements, such as. Grid rings, formed, which are fixed to support struts and form a shelter with their interior. In this case, the distance (opening) between the protective elements, which provide a material obstacle as protective structures, which restricts, in particular, the movement of a human body and / or a body part, in order to prevent the reaching of a hazardous area (eg a rotating impeller), from safety-related Reasons not to be too big. Depending on the diameter of the protective device, therefore, conventional protective devices have a high intrinsic weight, since a large number of protective elements must be arranged on them.

CONFIRMATION COPY In ventilation systems, it is often desirable that they have a high air flow. In addition to an increase in the fan unit, a high air flow rate can also be achieved by increasing the flow speed by increasing the speed of the fan unit. As the flow velocity increases, however, a vortex street, which according to its discoverer is referred to as the Karman vortex street, can form on the downstream side of the protective element flowed around, which consists of two rows of vertebrae with opposite directions of rotation. The nature of vortex formation is essentially determined by the Reynolds number, a measure used in fluid flow mechanics. If the flow velocity increases or the viscosity of the fluid decreases (as in the case of air compared to water), the Reynolds number increases. As the Reynolds number increases, these vertebrae can no longer cling to the body, and a vortex alternately breaks up and down, while the vortex re-forms on the other side. Due to this alternating vortex shedding, the flow direction around the cylinder changes periodically. These forces can cause the body around it to vibrate. Depending on the Wirbelablösefrequenz an audible sound may occur, so that an increase in the flow velocity can lead to unwanted noise.

In order to reduce this noise formation, US Pat. No. 6,866,474 B2 proposes a protective device for an air conditioning system which has protective elements, wherein the protective elements have an edge facing the air flow, through the structure of which the detachment of Karman vertebrae is reduced. disadvantageous However, it is obvious that the structuring of the edge is technically complex.

The invention and its advantages

The protective device according to the invention, in particular for a ventilation system, with the characterizing features of claim 1, has the advantage that it has at least one protective element which has an elongated, in cross-section a polygon, twisted profile or is a round tube, wherein the geometric design of the protective element significantly reduces the built-in mass, resulting in a weight reduction. In addition, the geometric design of the protective element ggfls. the detachment of Kärmän vertebrae and thus reduce the noise.

According to an advantageous embodiment of the protective device according to the invention, the elongated profile of a protective element made of solid material.

According to an additional advantageous embodiment of the protective device according to the invention, the elongate profile of a protective element is a hollow body (for example a triangular or quadrangular tube).

According to an additional advantageous embodiment of the protective device according to the invention, the circumferential center of the elongated profile is located on the longitudinal axis of the elongated profile. According to an additional advantageous embodiment of the protective device according to the invention, a protective element on different Verdrillwinkel and / or different Verdrillstetigkeiten.

According to an additional advantageous embodiment of the protective device according to the invention, a plurality of protective elements have different twist angles and / or different twisting properties.

According to an additional advantageous embodiment of the protective device according to the invention, the cross section of an elongate profile is a polygon.

According to a related advantageous embodiment of the protective device according to the invention, the polygon is a triangle, quadrangle, polygon or a star profile.

According to a related advantageous embodiment of the protective device according to the invention, the triangle is an equilateral triangle or the polygon is a regular polygon.

According to an additional advantageous embodiment of the protective device according to the invention, the protective device has a center around which at least one protective element is arranged in a spiral shape and / or at least one protective element in an annular manner.

According to an additional advantageous embodiment of the protective device according to the invention, the protection device has several on spaced apart arranged protective elements. Thus, the distance (opening) that exists between two protective elements corresponds to the distance that exists between the two limits limiting the respective protective space. In a twisted elongated profile having corner points lying on a perimeter, the shelter is bounded by the perimeter. Thus, the distance (opening) between two elongated profiles corresponds to the distance between their orbits. In the case of non-twisted round pipes, whose shelter is bounded by the outer circumference of the round pipe, the distance (opening) between the round pipes corresponds to the distance between the outer peripheries.

According to an additional advantageous embodiment of the protective device according to the invention, the protective device has at least one support strut.

According to an additional advantageous embodiment of the protective device according to the invention at least one protective element is connected to a support strut.

According to an additional advantageous embodiment of the protective device according to the invention, the protective device is designed as a protective grid and / or as a motor suspension.

Further advantages and advantageous embodiments of the invention are the following description, the drawings and claims removed. drawing

Embodiments of the subject invention are illustrated in the drawing and are explained in more detail below. Show it:

1 is a perspective view of a protective device according to the invention in the form of a protective grid,

2 and 3 is a front view of an elongated profile of a

Protection element,

4 is a front view of another elongated profile of a protective element,

Fig. 5 is a side view of an elongated profile of a

Protective element according to FIG. 2;

Fig. 6 is a side view of an elongated profile of a

Protective element according to FIG. 2 with indicated cross-sectional areas and

7 is a front view of an elongate profile of a

Protective element according to FIG. 2 with indicated cross-sectional areas. Description of the embodiments

Fig. 1 shows a perspective view of a protective device 1 according to the invention in the form of a protective grid, which consists of four support struts 2, are fixed to the concentric protective elements 3 in the form of lattice rings (preferably welded). Each support strut 2 consists of two parallel guided, twice over the high edge with different angles angled flat sections 4, the inner ends are connected to an inner flange 5 and the outer ends to an outer flange 6 together. Of course, instead of the flat sections 4 also differently shaped profiles, such as round profiles, can be used. Between the support struts 2, two round struts 7 are arranged in the same pitch. The protective elements 3 are preferably connected to each other at their intersection points (joints 8) with the flat sections 4 and the round bars 7 by welding. For the sake of simplicity, the short line contact between the protective element 3 and the flat profile 4 is also regarded as a crossing point.

2 and 3 show front views of an elongate profile 9 of a protective element 3. The elongate profile 9 has a triangular cross-sectional area 10, with corner points 11 of the elongate profile 9 being located on a circumference 14 having a circumferential center 12 and a radius 13 , By twisting the elongate profile 9, which may be a triangular wire, for example, about its longitudinal axis, which is perpendicular to the image plane and passes through the circumference center 12, the shelter formed by the elongated profile 9 increases, so that the initially in untwisted Condition given shelter, the is given by the edge length of the elongated profile 9, increased to the radius of the circumference 14. Since the triangular cross-sectional area 10 of the elongated profile 9 is only 41.3% of the area of a solid round wire, the extent by which its shelter is determined , which corresponds to radius 14, a material saving of 58.7% is achieved with the same shelter.

In Fig. 2 and Fig. 3, the elongated profile 9 is shown as a solid material. It would be conceivable that, instead of the elongate profile 9 made of solid material, an elongated hollow body (for example a triangular tube) having the same circumference would be used. By using an elongated hollow body and / or by twisting the material savings could be further increased.

4 shows a front view of another elongate profile 9 of a protective element 3. The elongated profile 9 is designed as a star profile which has a cross-sectional area 10. By cornering of the star profile about its longitudinal axis, which is perpendicular to the image plane and extends through the center of circumference 12, the shelter formed by the star profile increases, so that the initial In the untwisted state given shelter, which corresponded to the cross-sectional area 10, is now given by the circular area 15 of the circumference 14. Since the cross-sectional area 10 of the star profile is only a fraction of the area of a solid round wire whose circumference, by which its shelter is determined, corresponds to the perimeter 14, material savings are achieved for the same area of the shelter. FIG. 5 shows a side view of an elongated profile 9 of a protective element 3, and FIG. 6 shows a perspective view of an elongated profile 9 of a protective element 3 according to FIG. 2 with indicated cross-sectional areas 10. The elongate profile 9, which has a triangular cross-sectional area 10 is twisted about the longitudinal axis 16, whereby the shelter is increased.

7 shows a front view of an elongate profile 9 of a protective element 3 according to FIG. 2 with indicated cross-sectional areas 10.

In addition, the twisting creates a surface structure that reduces the separation of carm n-vortices, thus counteracting noise.

All in the description, the following claims and the drawings illustrated features may be essential to the invention both individually and in any combination.

LIST OF REFERENCE NUMBERS

1 protection device

2 support strut

3 grid ring

4 flat profile

5 inner flange ring

6 Outer flange ring

7 round strut

8 joints

9 Oblong profile

10 cross-sectional area

1 1 corner point

12 perimeter center

13 radius

14 perimeter

15 circular area

16 longitudinal axis

Claims

Protective device claims

1. Protection device (1), in particular for a ventilation system,

- With at least one protective element (3) and

with a protective space formed by the protective element (3),

characterized,

in that at least one protective element (3) has an elongated profile (9) with at least two corner points (11) which are located on a circumference (14) having a peripheral center point (12), a cross-sectional area (10) of the elongate profile (9) being smaller than a cross-sectional area of a circle centered circle, whose circumference delimiting the shelter area corresponds to the perimeter (14) of the elongate profile (9), the elongate profile (9) having a longitudinal axis (16) about which the elongated profile (9 ) is twisted to form a by the perimeter (14) limited shelter of the protective element (3), wherein a protective element (3) to at least one crossing point is connected to at least one support strut (2),

and or

in that at least one protective element (3) is a circular tube having an outer diameter, the cross-sectional area of which is smaller than a cross-sectional area of a circle having a circular center, whose circumference delimiting the protective space would correspond to the outer diameter of the elongate round tube.

2. Protection device (1) according to claim 1, characterized in that the elongate profile (9) of a protective element (3) is made of solid material.

3. Protection device (1) according to claim 1 or claim 2, characterized in that the elongate profile (9) of a protective element (3) is a hollow body.

4. Protection device (1) according to one of the preceding claims, characterized in that the circumferential center (12) of the elongate profile (9) on the longitudinal axis (16) of the elongate profile (9).

5. Protection device (1) according to one of the preceding claims, characterized in that a protective element (3) has different Verdrillwinkel and / or different Verdrillstetigkeiten.

6. Protection device (1), according to one of the preceding claims, characterized in that several protective elements Have (3) different Verdrillwinkel and / or different Verdrillstetigkeiten.

7. Protection device (1) according to one of the preceding claims, characterized in that the cross section of an elongated profile (9) is a polygon.

8. Protection device (1) according to claim 7, characterized in that the polygon is a triangle, quadrangle, polygon or a star profile.

9. Protection device (1) according to claim 8, characterized in that the triangle is an equilateral triangle or the polygon is a regular polygon.

10. Protection device (1) according to one of the preceding claims, characterized in that the protective device (1) has a center around which at least one protective element (3) spirally and / or at least one protective element (3) are arranged annularly.

11. Protection device (1) according to one of the preceding claims, characterized in that the protective device (1) has a plurality of spaced-apart protective elements (3).

12. Protection device (1), according to one of the preceding claims, characterized in that the protective device (1) has at least one support strut (2).

13. Protection device (1), according to claim 12, characterized in that at least one protective element (3) with a support strut (2) is connected.

14. Protection device (1) according to one of the preceding claims, characterized in that the protective device (1) is designed as a protective grid and / or as a motor suspension.