Double blower on one motor shaft

Abstract

A blower for a ventilator, comprising an electric motor with a motor shaft, wherein at least one blower wheel is arranged in the region of opposite ends of the motor shaft, which has a low-pressure area in the intake flow upstream of the blower wheel and a high-pressure area in the intake flow downstream of the blower wheel, wherein the two blower wheels have different intake areas and wherein the two blower wheels have different outlets, and wherein the blower has, in addition to a first blower stage used for ventilation, a second blower stage, wherein both blower stages are suitable for generating a ventilation pressure, and wherein the outlet of the second blower stage opens into the outlet area of ​​the first blower stage, characterized in that at least one blower wheel outlet is split into at least a first and a second branch.wherein at least one of the branches has a throttle and wherein at least one branch is used to supply control pressures or to cool the motor or other components.

Description

[0001] Blowers consisting of a motor and a fan wheel mounted on its shaft are used in many areas of technology today. These so-called radial blowers, in which the air flow is drawn in axially and expelled radially at the blower outlet, or axial blowers, in which the drawn-in gas is drawn in and expelled axially, are also used in ventilators, for example.

[0002] Such fans are disclosed, for example, in the following documents: DE 102 34 345 A1, DE 11 28 023 A, DE 697 019 A, US 1 080 763 A, US 3 102 483 A, US 5 388 956 A, EP 1 302 666 A1, WO 98 / 05 867 A1.

[0003] The intake area, which is located directly in front of the impeller, is in many cases at ambient pressure or has a lower pressure than the outlet area.

[0004] In many applications, engine cooling is also necessary to protect it from harmful operating temperatures.

[0005] The engines, and especially their bearings, are sometimes subjected to extreme loads. For example, the axial forces vary greatly when operating at different, suddenly changing speeds, and the bearings are therefore also exposed to various, suddenly changing force ratios. For example, the pressure in the intake area is usually lower than directly behind the impeller, which, in a single-fan engine, pushes the entire rotating assembly toward the intake area. This can lead to various, unacceptable contact points within the rolling bearings, particularly in the bearings. The frequent load changes across speeds also have a material fatigue effect on the bearings and the entire assembly.

[0006] To accommodate the frequent and sometimes sudden load changes, bearings are often preloaded. A spring can be mounted on either the inner or outer ring, allowing the rings to move in position. This arrangement requires sometimes very strong and costly springs, as well as complex shaft and bearing geometry.

[0007] Another disadvantage of the state of the art is the automatic degreasing of the bearings associated with fan motors. These are lubricated, and the grease is pressed out of the bearings by the different pressure conditions in front of and behind the fan wheel.

[0008] To limit degreasing, many motor designs incorporate vent holes in the walls supporting the ball bearings to minimize the degreasing force by maintaining a low flushing flow. This degreasing is often the cause of bearing and, consequently, fan failure.

[0009] Furthermore, many devices use additional fans as cooling fans to cool power electronics, motors, and other temperature-sensitive components. In the field of ventilation technology, where fans are also used to generate airway pressure, a build-up of control pressure is necessary to operate pneumatic valves. Therefore, these devices usually use a second pressure / flow source, which is also provided by a fan. This requires additional installation space and control electronics and is associated with increased costs.

[0010] A further disadvantage of the state of the art is that poor acceleration (dynamics) is achieved at high speeds and moments of inertia of the impellers.

[0011] WO 2004 / 108 198 A1 discloses a blower for a ventilator with two blower stages, wherein the outlet of the first blower stage opens into the inlet area of ​​the second blower stage.

[0012] The object of the present invention is to construct a blower of the type mentioned in the introduction in such a way that improved operating characteristics are provided with a compact construction.

[0013] This object is achieved according to the invention by a blower having the features of the single claim.

[0014] One embodiment describes a fan having an electric motor with a motor shaft, wherein at least one fan wheel is arranged in the region of opposite ends of the motor shaft, which fan wheel has a region of low pressure in the intake flow path in front of the fan wheel and a region of higher pressure in the intake flow path behind the fan wheel.

[0015] One advantage of the invention is the even distribution of forces on the motor shaft when the impellers are selected identically. Both fans generate the same forces in opposite directions. This increases the service life of the bearings and other components, as they are no longer subjected to transverse forces and sudden load changes, but rather to equal, opposing axial forces. The resulting total force acting on the shaft approaches zero; a spring to absorb these loads and forces is no longer required.

[0016] A further advantage of the invention is the increased dynamics of the blowers, since the arrangement of two impellers allows for a smaller diameter compared to a single impeller with the same output power. This has a positive effect on the moment of inertia, as this is proportional to the square of the radius.

[0017] Here, too, the shared use of the same shaft for two impellers has a positive effect on the application, as the engine's waste heat also increases with increasing speeds. However, by simultaneously increasing the cooling flow, this waste heat can be dissipated. With clever geometries, separate cooling electronics are not necessary; cooling always occurs based on the combined speed of the two impellers.

[0018] The invention provides that both impellers have a different intake area.

[0019] According to the invention, the two impellers also have different outlets. For example, one impeller can be used to supply breathing gas, while the other can be used to apply control pressure and cooling flows.

[0020] At least one outlet splits into at least two branches, with this branching occurring downstream of the merging of the two outlets. This has the advantage that gases with different flows and pressures can be made available for different applications. These applications can be those already mentioned above.

[0021] In order to further design the branches in such a way that the gas states required for different applications are achieved, a throttle is installed in at least one of the branches. Character description Fig. 1: Representation of an embodiment according to the invention.

[0022] Fig.Figure 1 shows a double blower (1) with two intake areas and a branched outlet (17). The second outlet (10) is divided into two branches, with the first branch (18) flowing into the first outlet. The second branch (19) also has a throttle (20) for influencing the gas flow for another application.

Claims

[1] A fan for a ventilator, which has an electric motor with a motor shaft, wherein in the region of opposite ends of the motor shaft at least one fan wheel is arranged, which has a region of low pressure in the intake flow path in front of the fan wheel and a region of higher pressure in the intake flow path behind the fan wheel, wherein the two fan wheels have a different intake area and wherein the two fan wheels have a different outlet and wherein the fan has a second fan stage in addition to a first fan stage used for ventilation, wherein both fan stages are suitable for generating a ventilation pressure and wherein the outlet of the second fan stage opens into the outlet area of ​​the first fan stage, characterized bythat at least one fan wheel outlet is separated into at least a first and a second branch, wherein at least one of the branches has a throttle and wherein at least one branch is used to supply control pressures or is used to cool the motor or other components.

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