Side channel compressor with optimized inlet opening geometry

Abstract

The aim of the invention is to provide a side channel compressor which produces as little noise as possible for a heating device with improved efficiency. This is achieved in that the side channel compressor (10) which produces as little noise as possible has a first housing portion (11) with rotatable fan blades (16) and a second housing portion (12), said first housing portion (11) and second housing portion (12) enclosing a flow channel (13) with an inlet (14) and an outlet (15), wherein an opening surface (F) of the inlet (14) has a side portion (20), the distance (A1) of which to a separating plane (T) between the first housing portion (11) and the second housing portion (12) increases in the direction of rotation (R) of the fan blades (16).

Description

[0001] Side channel blower with optimized inlet opening geometry

[0002] The present invention relates to a side channel compressor and a heating device comprising such a side channel compressor.

[0003] For heating interior spaces, heaters are known that generate heat by burning a fuel, which is then transferred to the interior air via a heat exchanger. Heaters that operate according to this principle are used primarily in vehicles or mobile living facilities such as motor homes, caravans, or mobile homes.

[0004] To burn the usually gaseous fuel in the combustion chamber of the heater, oxygen-containing combustion air must be supplied to the combustion chamber. The combustion air is ambient air, which is supplied to the combustion chamber or a burner antechamber located upstream of the combustion chamber via a side channel compressor.

[0005] A side channel blower, also known as a side channel compressor, is a type of blower that compresses a gaseous medium or fluid (such as air or an air-gas mixture) through a side channel using rotating impellers. They are often used to provide compressed air for various processes, such as fuel combustion.

[0006] The principle of side channel compressors is based on centrifugal force. Rotating impellers accelerate the fluid, such as air and gas, in the side channel, and centrifugal force pushes the fluid outward. The annular casing of the side channel compressor deflects the fluid and returns it to the base of subsequent blades. The rotation creates a pressure difference between the inlet and outlet ports. This pressure difference enables the compressor to transport the fluid through the system.

[0007] The side channel compressor has an inlet through which the ambient air flows into a substantially annular flow channel. A fan impeller rotates within the flow channel, conveying and compressing the ambient air from the inlet to an outlet of the side channel compressor. The mixing of the fuel with the ambient air can take place upstream or downstream of the side channel compressor.

[0008] Side channel compressors of the type described above are known, for example, from EP 3597998 Bl and EP 3869098 Bl.

[0009] Furthermore, DE 19708952 A1 discloses a side channel compressor with an impeller provided with blades, which is rotatable for compressing gas in a housing equipped with a side channel, wherein the cross section of the side channel tapers from a suction side towards a pressure side.

[0010] EP 1165965 B1 further describes a side channel compressor, wherein an elliptically formed side channel is fluidically optimized in such a way that a major axis of the ellipse lies slightly within a cover of the side channel compressor.

[0011] Furthermore, DE 4220153 A1 discloses a vortex flow blower with a cross-section reducer arranged within a flow passage.

[0012] DE 4421604 CI also describes a side channel compressor with an impeller with blades which have different spacing angles to each other.

[0013] The efficiency of the side channel compressor, i.e., the airflow rate per unit time, depends largely on the airflow pattern within the flow channel. For optimal flow, the airflow in the flow channel forms a spiral flow, which is caused by the airflow alternating between the fan impeller blade areas and a free flow channel area without blades.

[0014] The flow pattern within the flow channel, and in particular the formation of the spiral flow, depends primarily on the geometry of the side channel compressor and its components. Particularly in areas where the flow is strongly deflected, such as the inlet or outlet, flow blockages or backflows can occur, which negatively impact the efficiency of the side channel compressor.

[0015] The present invention is based on the object of providing a side channel compressor with improved efficiency. It is also an object of the invention to provide a side channel compressor that is as quiet as possible.

[0016] The object according to the invention is achieved by a side channel compressor, comprising a first housing section with rotatable fan blades and a second housing section, wherein the first housing section and the second housing section enclose a flow channel with an inlet and an outlet, wherein an opening surface of the inlet has a side section whose distance from a parting plane between the first housing part and the second housing part increases in the direction of rotation of the fan blades.

[0017] The first housing section and the second housing section enclose, in particular, a substantially annular flow channel that is closed except for the inlet and outlet areas. Preferably, the first housing section and the second housing section are separate elements. The first housing section is designed, in particular, in the form of a fan wheel, so that the fan blades are rigidly arranged on the first housing section. The first housing section is connected to the second housing section and rotatable relative thereto.

[0018] Alternatively, it is conceivable for the first housing section to be rigidly connected to the second housing section, and for a fan wheel having fan blades to be rotatably arranged in the first housing section. All statements below refer to the embodiment in which the first housing section is designed as a fan wheel. However, all statements are analogously applicable to a fan wheel separate from the first housing section.

[0019] The flow channel preferably has a first region comprising the first housing section with the fan blades and a second region adjacent to the first region in the second housing section without the fan blades. During rotation of the first housing section, a fluid flows into the chambers between the fan blades and is initially deflected radially outward due to centrifugal force, reflected there by the housing wall, and flows radially inward into the second housing section. The terms "radially inward" and "radially outward" refer to the annular shape of the flow channel and the rotational axis of the fan blades, respectively. From the second housing section, the fluid rises back into the chambers between the fan blades. At the same time, the fluid moves in the direction of rotation of the fan blades, creating a spiral flow within the flow channel.

[0020] The parting plane between the first and second housing parts runs, in particular, parallel to a rotational plane of the fan blades. The ends of the fan blades are, in particular, arranged directly adjacent to the parting plane.

[0021] For effective operation of the side channel compressor, the fluid flow entering the flow channel through the inlet should, if possible, follow a spiral path. As the fan blades rotate, a portion of the conveyed fluid exits the flow channel through the outlet after passing through it, while the remaining fluid remains in the chambers between the fan blades and is conveyed through a separating section located in the second housing section between the outlet and the inlet into the inlet area. Here, this fluid encounters additional fluid entering the flow channel through the inlet.

[0022] Due to the two fluid flows colliding in the inlet area of ​​the flow channel, a flow blockage or backflow of the fluid can occur. To prevent this, an optimized geometry of the inlet opening is provided, which has a side section whose distance from the parting plane between the first housing part and the second housing part increases in the direction of rotation of the fan blades.

[0023] The opening area of ​​the inlet is formed in particular in a wall surface of the flow channel, in particular in the second housing section. The inlet is here in particular the point at which the fluid flow directly enters the annular flow channel. The inlet can optionally be connected to a supply line or a supply line section for the fluid.

[0024] Due to the increasing distance between the side section and the parting plane, the fluid flow entering the flow channel is advantageously guided or deflected in such a way that the fluid flow is guided past the fluid flow exiting the chambers of the fan blades and is therefore essentially not mixed with or influenced by it. While the fluid flow from the chambers flows radially outwards, the fluid flow entering through the inlet can flow radially inwards, offset in the axial direction, past the fluid flow from the chambers. The axial direction here refers to the direction of rotation of the fan blades. Both fluid flows are then deflected by the walls of the flow channel or of the housing formed by the two housing sections and move spirally through the flow channel towards the outlet.This creates two intertwined spiral flows, whereby these spiral flows can develop optimally, particularly in the area of ​​the inlet, due to the opening geometry, without the two flows adversely affecting each other.

[0025] The side section of the inlet opening, whose distance from the parting plane increases, influences the incoming fluid flow by guiding it over the sloping or inclined side section. In other words, the side section extends, in particular, obliquely from the parting plane toward a bottom region of the flow channel opposite the fan blades.

[0026] A side section of the opening surface is understood to mean, in particular, a section of the circumference of the opening surface. The side section can form an edge section or a wall section of the part of the housing forming the inlet.

[0027] The inclined side section defines or forms, in particular, a sloped edge or a sloped wall section in the second housing section. The slope of the side section results from the increasing distance between the side section and the parting plane. This sloped wall section forms, in particular, a type of flow guide surface or flow guide edge. The incoming fluid flows accordingly over the sloped flow guide surface or flow guide edge and is then guided in the direction of rotation of the fan blades behind the flow guide surface or flow guide edge into the flow channel or onto the spiral path.

[0028] In other words, the sloped section of the opening creates a blocked area in the flow channel immediately behind the inlet for the fluid entering through the inlet. If the sloped section were not present, the incoming fluid flow would collide with the fluid flow from the chambers between the fan blades in this blocked area, creating a risk that the two fluid flows would influence each other, resulting in backflow.

[0029] Preferably, the increase in the distance between the parting plane and the side section of the opening surface has a linear profile. In other words, the side section is straight. Alternatively, however, other profiles are also conceivable, for example, an arcuate, in particular convex or concave, profile of the side section.

[0030] The opening surface is preferably polygonal, in particular triangular, square, or pentagonal. The side section of the opening surface forms a side surface of the polygon.

[0031] As already described above, the side channel compressor preferably has a separating section between the inlet and the outlet. This separating section is arranged in particular in the second housing section and prevents fluid in the region of the second housing section from passing from the outlet to the inlet. The fan blades move in particular over an upper side of the separating section. During operation of the side channel compressor, there is a continuous increase in pressure of the fluid in the flow channel between the inlet and outlet. A portion of the compressed fluid is enclosed in the chambers between the fan blades, conveyed over the separating section, and then expands into the inlet region. Both the relative movement between the blade edges and the edge geometry of the separating section, as well as the expansion of the fluid, generate noise.

[0032] The separating section therefore preferably has an inlet-side wall surface with two wall surface sections arranged at an angle to one another, wherein an inner edge between the two wall surface sections runs radially outside a central axis of the flow channel. The angle is preferably between 40° and 120°, particularly preferably between 50° and 110°, most preferably between 60° and 100°. The central axis runs through the center of the flow channel based on its cross-section along an extension of the flow channel in the direction of rotation of the fan blades or along the annular shape of the flow channel. The center axis of the spiral flow of the fluid within the flow channel is usually slightly offset radially outwards from the central axis of the flow channel.The above-described design of the separating section results in the flow channel in this area having a tip pointing opposite to the fluid flow direction, allowing the flow from the chambers to expand into the tip region and into the center of the spiral flow. This measure has been shown to advantageously reduce noise during operation of the side channel compressor.

[0033] The inlet is preferably arranged, in particular substantially directly, adjacent to the separating section, so that the oblique side section of the opening surface, the distance of which from the separating plane increases in the direction of rotation, extends either directly or at a distance from the separating section. This advantageously creates a region behind the separating section in which the fluid can expand from the chambers between the fan blades and does not impinge on the fluid flow entering through the inlet. A cross-sectional area of ​​the flow channel preferably has at least one local maximum along its course from the inlet to the outlet. This means that an expansion or enlargement of the cross-sectional area of ​​the flow channel can occur locally at a predetermined position, and the cross-sectional areas upstream and downstream of this position are smaller.It has been shown that a local cross-sectional expansion in the flow channel leads to a noise reduction during operation of the side channel blower. The cross-sectional expansion can be achieved, for example, by locally increasing the depth of the flow channel.

[0034] Preferably, the local maximum is located at a distance from the inlet relative to the flow channel, wherein the distance corresponds to a quarter of the wavelength of an interference tone generated during operation of the side channel compressor. The generated interference tone, or its frequency and wavelength, depend on the number of fan blades and the speed of the fan blades. Accordingly, the distance of the local maximum can be determined depending on one or both of the aforementioned parameters. When calculating the distance, the speed of sound in the medium to be conveyed and the influence of the medium temperature can also be taken into account.

[0035] Preferably, the flow channel has an end section arranged upstream of the outlet, wherein the end section has a gradient viewed in the flow direction of a fluid stream, wherein an angle between the flow channel in the end section and the separation plane is preferably between 21° and 35°, particularly preferably between 23° and 33°, and most particularly preferably between 26° and 30°. In this way, particularly good flow efficiency and low noise levels can be achieved.

[0036] Preferably, a cross-sectional area of ​​the flow channel, viewed in the direction of flow of the fluid stream, has a local maximum, particularly immediately before the end section. The cross-sectional expansion can also be achieved at this point, for example, by locally increasing the depth of the flow channel. In this way, flow congestion can advantageously be prevented, which in turn increases flow efficiency and leads to low noise levels.

[0037] Preferably, the flow channel has exclusively the two local maxima described above and in particular no further local maxima.

[0038] Preferably, the flow channel has a decreasing cross-sectional area when viewed globally, i.e., when considering its entire course from the inlet to the outlet. One or both of the aforementioned local maxima of the cross-sectional area may be present locally along the course of the flow channel. In other words, the cross-sectional area of ​​the flow channel decreases substantially continuously from the inlet to the outlet, with the exception of the local maxima, where the flow channel expands in sections.

[0039] The object of the invention is further achieved by a heating device comprising a side channel compressor with the aforementioned features.

[0040] The heater is used primarily to heat an interior space. For example, the heater can be installed in a vehicle or a mobile home, such as a camper van, caravan, or mobile home.

[0041] The present invention is explained in more detail below with reference to the figures. They show:

[0042] Figure 1: a sectional view of a heater,

[0043] Figure 2: a plan view of a second housing section of a side channel compressor of the heater,

[0044] Figure 3: a sectional view along the line AA of Figure 2,

[0045] Figure 4: a schematic representation of a simulated flow in a flow channel of the side channel compressor, Figure 5: a plan view of an opening area of ​​an inlet of the side channel compressor,

[0046] Figure 6 is a partial plan view of the second housing section of the side channel compressor,

[0047] Figure ? a schematic representation of a central flow axis in a flow channel of the side channel compressor,

[0048] Figure 8 shows a representation of the course of a height of the flow channel from the inlet to the outlet, and

[0049] Figure 9 shows a detailed view of an end section of the flow channel.

[0050] Figure 1 shows the structure of a heater 100 for heating an interior space. In this illustration, the heater 100 is shown without a housing. The heater 100 comprises a recirculation fan 1 driven by a drive 2 for drawing in ambient air. The ambient air is used as combustion air and is fed via an ambient air supply 9b to an inlet 14 of a side channel compressor 10 of the heater 100. A fuel is supplied via a gas valve 5, which, together with the ambient air, is fed through the side channel compressor 10 to a burner antechamber 4. From the burner antechamber 4, the mixture of ambient air and fuel is fed to a burner 6, which combusts the mixture in a flame tube 7. Heat from the flame tube 7 is transferred via a heat exchanger 8 to the air to be heated in an interior space to be heated.

[0051] Figure 2 shows a plan view of the underside of a second housing section 12 of the side channel compressor 10. The side channel compressor 10 has an inlet 14 through which the ambient air flows into a flow channel 13, wherein the flow channel 13 is essentially annular and extends from the inlet 14 to an outlet 15 of the side channel compressor 10. The direction of the flow S is indicated here by an arrow. Figure 3 shows a sectional view along the line AA from Figure 2. Shown are a first housing section 11 and the second housing section 12, wherein the two housing sections 11, 12 enclose the flow channel 13 or form it between them. Also shown is the lateral outlet 15. The first housing section 11 and the second housing section 12 are designed as separate components and separated from one another by a parting plane T.The first housing section 11 has fan blades 16, which are rigidly arranged on the first housing section 11. The first housing section 11 is thus designed as a fan wheel and is rotatable relative to the second housing section 12. Chambers 17 are formed between the fan blades 16.

[0052] Figure 4 shows a schematic representation of the flow channel 13 with a simulated course of the flow S. Due to the structure of the flow channel with the fan blades 16 in the first housing section 11 and the free area in the second housing section 12, a spiral flow results.

[0053] Figure 4 further shows a separating section 21 of the side channel compressor 10, which separates the inlet 14 and the outlet 15 in the second housing section 12. On the inlet side, the separating section 21 has two wall surfaces 18a, 18b, which are arranged at an angle to one another and form or enclose an inner edge 19. The inner edge 19 is arranged radially outwardly offset from a central axis Z of the flow channel 13. The central axis Z of the flow channel 13 is generally radially inwardly offset from a central axis of the spiral flow S, which is not shown here, but runs approximately above the inner edge 19.

[0054] In the circular region B, it can be seen how the spiral flow S behaves in the region of the inlet 14. In this region, air flows from the chambers 17 and is conveyed by the rotating first housing section 11 or its fan blades 16 via the dividing section 21 into the inlet region. It is shown how the flow from the chambers 17 flows outwards towards an outer wall of the flow channel 13 and is deflected there to continue flowing on the spiral path. This advantageous spiral flow pattern directly behind the inlet is made possible by the geometry of the inlet opening, wherein an opening area F of the inlet has a side section 20 whose distance A1 from the dividing plane T increases when viewed in the direction of rotation R and which, starting from the dividing plane T and viewed in the direction of rotation of the first housing section 11, has an increasing profile, as shown in Figure 5.Due to the rising profile of this side section 20 of the opening area F, the inlet 14 is shaped such that the area B, into which the air flows out of the chambers 17, is blocked for the air flowing in through the inlet 14, so that the two air flows cannot mix in this area and the formation of the spiral flow S is prevented. Due to the side section 20, a flow guiding edge is thus provided which, as viewed in Figure 5, guides the air flow entering through the inlet 14 upwards over the air flowing out of the chambers 17. The incoming flow is then deflected at a radially inner wall of the flow channel 13 and will then also spread further in a spiral shape into the flow channel 13 and wind around the spiral flow of air from the chambers 17.

[0055] The inlet 14 shown in Figure 5 has a substantially pentagonal opening area F. Alternative geometries are also conceivable, so that the opening area F could also be square or triangular, for example. In these cases, the lower short side section in the square configuration or, in addition, the left short side section for the triangular configuration would be omitted, whereby the term "left" refers to the illustration in Figure 5.

[0056] Figure 6 shows a further illustration of the side section 20 of the opening area F of the inlet 14 when viewed from the flow channel 13. Due to the geometry of the opening area F, an oblique edge is formed in the inlet 14 in the region of the side section 20, the distance of which from the parting plane T increases as viewed in the direction of rotation R, which acts as a flow guiding edge.

[0057] Figure 7 shows a top view of the second housing section 12 with the flow channel 13, which extends between the inlet 14 and the outlet 15. Figure 8 shows a profile of the flow channel 13, starting from the inlet 14 along the extension X of the flow channel 13 to the outlet 15. The profile plotted in Figure 8 corresponds to the profile or the depth of the flow channel along the dashed line in Figure 7.

[0058] The profile of the flow channel 3 shown in Figure 8 refers to the course starting from a lowest position within the flow channel 13 in the second housing section 12 up to the parting plane T. Here, accordingly, only a depth of the flow channel 13 down to the fan blades 16 or the first housing section 11 is considered. Figure 8 shows that, when viewed from the inlet 14 to the outlet 15, the depth of the flow channel 13 decreases continuously from a global perspective. Since, with respect to the cross-section, only the depth of the flow channel 13 is varied and, in particular, the radial width remains essentially constant, a decrease in the depth corresponds to a decrease in the cross-sectional area of ​​the flow channel.

[0059] Viewed locally, the profile of the flow channel 13 exhibits two local maxima M1 and M2, at which its depth and thus cross-sectional area are locally increased. The first local maximum M1 lies at a predetermined distance A2 from the inlet 14, whereby this distance A2 corresponds to a quarter of a wavelength of an interference tone generated during operation of the side channel compressor 10. The second local maximum M2 is located immediately in front of an end section E of the flow channel 13, upstream of the outlet 15.

[0060] Figure 9 shows a sectional view through the area of ​​the outlet 15. It shows the end section E, which, viewed in the direction of flow, has a rise such that the end section E or an imaginary extension of the end section E forms an angle W with the parting plane T. The angle W can be, for example, 25°.

[0061] 100 heater

[0062] 1 recirculation fan wheel

[0063] 2 Drive for recirculation fan wheel

[0064] 3 Drive for the side channel blower

[0065] 4 Burner anteroom

[0066] 5 Gas valve

[0067] 6 burners

[0068] 7 Flame tube

[0069] 8 heat exchangers

[0070] 9a Exhaust outlet

[0071] 9b Ambient air supply

[0072] 10 pages channel compressor

[0073] 11 first housing section

[0074] 12 second housing section

[0075] 13 Flow channel

[0076] 14 Entrance

[0077] 15 Outlet

[0078] 16 fan blades

[0079] 17 Chamber between fan blades

[0080] 18a, b Wall surface sections

[0081] 19 inner edge

[0082] 20 page section

[0083] 21 Separation section

[0084] T parting line

[0085] B area

[0086] F Opening area of ​​the inlet

[0087] Z central axis of the flow channel

[0088] S spiral flow R direction of rotation of the first housing section

[0089] All distance

[0090] A2 distance

[0091] X Extension between inlet and outlet

[0092] W angle

[0093] Ml, M2 local maximum

Claims

Claims 1. Side channel compressor (10), comprising a first housing section (11) with rotatable fan blades (16) and a second housing section (12), wherein the first housing section (11) and the second housing section (12) enclose a flow channel (13) with an inlet (14) and an outlet (15), wherein an opening area (F) of the inlet (14) has a side section (20) whose distance (Al) to a parting plane (T) between the first housing section (11) and the second housing section (12) increases in the direction of rotation (R) of the fan blades (16).

2. Side channel compressor (10) according to claim 1, wherein the increase in the distance (Al) between the parting plane (T) and the side section (20) has a linear progression.

3. Side channel compressor (10) according to one of the preceding claims, wherein the opening area (F) is polygonal, in particular triangular, square or pentagonal.

4. Side channel compressor (10) according to one of the preceding claims, comprising a separating section (21) between the inlet (14) and the outlet (15).

5. Side channel compressor (10) according to claim 4, wherein the separating section (21) has an inlet-side wall surface with two wall surface sections (18a, 18b) arranged at an angle to one another, wherein an inner edge (19) between the two wall surface sections (18a, 18b) extends radially outside a central axis (Z) of the flow channel (13), wherein preferably the inlet (14) is arranged adjacent to the separating section.

6. Side channel compressor (10) according to one of the preceding claims, wherein a cross-sectional area of ​​the flow channel (13) along its course from the inlet (14) to the outlet (15) has at least one local maximum (Ml).

7. Side channel compressor (10) according to claim 6, wherein the local maximum (Ml) is arranged at a distance (A2) from the inlet (14) relative to the course of the flow channel (13), wherein the distance (A2) corresponds to a quarter of the wavelength of an interference tone generated during operation of the side channel compressor (10).

8. Side channel compressor (10) according to one of the preceding claims, wherein the flow channel (13) has an end section (E) arranged in front of the outlet (15), wherein the end section (E) has a gradient when viewed in the flow direction of a fluid flow, wherein an angle (W) between the flow channel (13) in the end section (E) and the parting plane (T) is preferably between 21° and 35°, particularly preferably between 23° and 33°, most particularly preferably between 26° and 30°.

9. Side channel compressor (10) according to claim 8, wherein a cross-sectional area of ​​the flow channel (13) viewed in the flow direction of the fluid flow, in particular immediately before the end section (E), has a local maximum (M2).

10. Heating device (100) comprising a side channel compressor (10) according to one of the preceding claims.

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