FAN AND METHOD FOR DETERMINING A MEDIA FLOW MOVED BY THE FAN

Abstract

A fan is described, with the aid of which a volume flow and/or a mass flow of a medium moved by the fan (1) can be determined. This fan comprises an electric motor (2) and an impeller (3) driven by the electric motor (2), wherein the impeller (3) moves a gaseous medium in a media flow from an inflow side (5) to an outflow side (7). The fan additionally comprises a pressure sensor system, a speed ascertainment system, and an evaluation unit. The pressure sensor system is designed to ascertain an actual pressure difference (Δp*) between a first region (10) and a second region (13), wherein the first region (10) and/or the second region (13) is/are formed in the electric motor (2), wherein a pressure (p.sub.A) prevails in the first region (10), which corresponds to a pressure (p.sub.1) present on the inflow side, wherein a pressure (p.sub.B) prevails in the second region (13), which corresponds to a pressure (p.sub.2) present on the outflow side. The speed ascertainment system is designed to ascertain an actual speed (n) of the impeller (3). The evaluation unit is finally designed to quantitatively determine a mass flow and/or a volume flow of the medium based on the actual pressure difference (Δp*), the actual speed (n), and a pressure characteristic curve of the fan (1).

Furthermore, an electric motor for this fan and a corresponding method are disclosed.

Claims

1. A fan for determining a media flow moved by the fan (1), having an electric motor (2) and an impeller (3) driven by the electric motor (2), wherein the impeller (3) moves a gaseous medium in a media flow from an inflow side (5) to an outflow side (7), characterized by: a pressure sensor system, a speed ascertainment system, and an evaluation unit, wherein the pressure sensor system is designed to ascertain an actual pressure difference (Δp*) between a first region (10) and a second region (13), wherein at least one of the first region (10) and the second region (13) are formed in the electric motor (2), wherein a pressure (p.sub.A) prevails in the first region (10) which corresponds to a pressure (p.sub.1) present on the inflow side, wherein a pressure (p.sub.B) prevails in the second region (13) which corresponds to a pressure (p.sub.2) present on the outflow side, wherein the speed ascertainment system is designed to ascertain an actual speed (n) of the impeller (3), and wherein the evaluation unit is designed to determine at least one of a mass flow and a volume flow of the medium based on the actual pressure difference (Δp*), the actual speed (n), and a pressure characteristic curve of the fan (1).

2. The fan as claimed in claim 1, wherein the pressure sensor system comprises a first and a second absolute pressure sensor (14, 15), wherein the first absolute pressure sensor (14) measures a pressure (p.sub.A) in the first region (10) and the second absolute pressure sensor (15) measures a pressure (p.sub.B) in the second region (13).

3. The fan as claimed in claim 2, wherein the first absolute pressure sensor (14) is arranged in the first region (10) or in a first measurement chamber connected via a hose or duct (23) to the first region (10).

4. The fan as claimed in claim 2, wherein the second absolute pressure sensor (15) is arranged in the second region (13) or in a second measurement chamber connected via a hose or duct (23) to the second region (13).

5. The fan as claimed in claim 1, wherein the pressure sensor system comprises a differential pressure sensor (22), wherein a first sensor surface of the differential pressure sensor (22) is subjected to a pressure (p.sub.A) in the first region (10) and a second sensor surface of the differential pressure sensor (22) is subjected to a pressure (p.sub.B) in the second region (13).

6. The fan as claimed in claim 1, further comprising a bulkhead (11), which is formed inside the electric motor (3), wherein the bulkhead (11) prevents or at least significantly reduces a pressure equalization between the first region (10) and the second region (13).

7. The fan as claimed in claim 1, wherein the impeller (3) is connected to a motor shaft (4″), wherein the motor shaft (4″) is led through a bearing tube (19) in the electric motor (2) and is rotatably mounted by means of at least one bearing (21), in that the motor shaft (4″) comprises a feedthrough (18) which connects an opening on a front end of the motor shaft (4″) to an opening on a long side of the motor shaft (4″), and in that the first region (10) or the second region (13) is formed in the bearing tube (19).

8. The fan as claimed in claim 1, wherein the impeller (3) is connected to a motor shaft (4′), wherein the motor shaft (4′) is led through a bearing tube (19) in the electric motor (2) and is rotatably mounted by means of at least one bearing (21), in that the motor shaft (4′) comprises a feedthrough (9), which connects openings at the two front ends of the motor shaft (4′) to one another, and in that the first region (10) or the second region (13) is formed on one of the two front ends of the motor shaft (4′).

9. The fan as claimed in claim 1, wherein the first region (10) is formed at an air gap, wherein the air gap is formed between rotor and stator of the electric motor (2) and establishes a connection between surroundings of the electric motor and the first region (10) or the second region (13).

10. The fan as claimed in claim 1, further comprising an electronics housing (8) is-formed on the outflow side on the electric motor (2), wherein the second region (13) or the first region (10) is formed in the electronics housing (8).

11. The fan as claimed in claim 1, further comprising at least one of a temperature sensor and a humidity sensor, wherein the temperature sensor measures a temperature of the medium moved by the fan (1) and the humidity sensor measures a humidity of the medium moved by the fan (1) and wherein measured values obtained by the temperature sensor and the humidity sensor are transferred to the evaluation unit to ascertain a density of the medium.

12. The fan as claimed in claim 1, further comprising a memory, wherein the pressure characteristic curve is stored in the memory.

13. The fan as claimed in claim 1, further comprising a communication unit, by means of which values for at least one of the mass flow and the volume flow determined by the evaluation unit can be communicated to at least one of a management unit and a higher-order regulating unit.

14. The fan as claimed in claim 1, wherein the electric motor is designed as an electronically commutated motor—EC motor.

15. The fan as claimed in claim 1, wherein the electric motor has a stator and a rotor rotatably mounted relative to the stator and wherein the rotor is coupled to the impeller of the fan.

16. A method for determining a media flow moved by a fan, wherein the fan (1) comprises an electric motor (2) and an impeller (3) driven by the electric motor (2), wherein the method comprises the following steps: ascertaining an actual pressure difference (Δp*) between a first region (10) and a second region (13), wherein the first region (10) and the second region (13) are formed in the electric motor (2), wherein a pressure (p.sub.A) prevails in the first region (10), which pressure corresponds to a pressure (p.sub.1) present on the inflow side, wherein a pressure (p.sub.B) prevails in the second region (13), which pressure corresponds to a pressure (p.sub.2) present on the outflow side, ascertaining an actual speed (n) of the impeller (3), and determining a volume flow and/or a mass flow of the media flow based on the actual pressure difference (Δp*), the actual speed (n), and a pressure characteristic curve of the fan (1).

17. The method as claimed in claim 16, wherein the pressure characteristic curve is ascertained during a calibration measurement of the fan (1) or a fan of the same type.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS

[0049] FIG. 1 shows a section through an exemplary fan according to the prior art,

[0050] FIG. 2 shows a first exemplary embodiment of a fan according to the disclosure having a hollow shaft and a first and second region separated by a bulkhead,

[0051] FIG. 3 shows a diagram having a dependency of various differential pressures on a volume flow conveyed by the fan,

[0052] FIG. 4 shows an enlargement in the region of a bulkhead having an exemplary arrangement of an absolute pressure sensor, wherein the enlargement shows an embodiment similar to FIG. 2,

[0053] FIG. 5 shows an enlargement in the region of a bulkhead, having another exemplary arrangement of an absolute pressure sensor, wherein the enlargement shows an embodiment similar to FIG. 2,

[0054] FIG. 6 shows a section through a second exemplary embodiment of a fan according to the disclosure having a partially hollow shaft, a first region in a bearing tube, and a second region in an electronics housing,

[0055] FIG. 7 shows a modification of the exemplary embodiment according to FIG. 6, in which the actual pressure difference is measured by means of a differential pressure sensor,

[0056] FIG. 8 shows a section through an electric motor of a third exemplary embodiment of a fan according to the disclosure having a differential sensor and a first region formed in an electronics housing and a second region formed outside the electronics housing,

[0057] FIG. 9 shows a section through an electric motor of a fourth exemplary embodiment of a fan according to the disclosure having a differential pressure sensor and a feedthrough formed by a pressure duct to a first region, and

[0058] FIG. 10 shows a variant of the fourth exemplary embodiment of a fan according to the disclosure according to FIG. 9.

DETAILED DESCRIPTION OF THE DISCLOSURE

[0059] FIG. 1 shows a section through an exemplary fan, which is known from the prior art and from which each of the exemplary embodiments described hereinafter originate. In the description of this known fan, elements which also occur or can occur in an exemplary embodiment of the fan according to the disclosure are provided with the same reference signs as in the exemplary embodiments.

[0060] The fan shown in FIG. 1 comprises an electric motor 2 and an impeller 3, which is rotatably mounted around a motor shaft 4 relative to the electric motor 2 and is driven by the electric motor 2. The impeller 3 and thus the fan moves a media flow—in the present case an air flow—from an inflow side 5 through an inlet nozzle 6 and the impeller 3 to an outflow side 7. On the outflow side, an electronics housing 8 is arranged on the electric motor 2, in which electronics of the electric motor can be arranged. These electronics can generate, for example, a system of feed signals, wherein the system of feed signals can generate a rotating field in the electric motor which induces a rotational movement of the rotor. During operation of the fan, a pressure p.sub.1 results on the inflow side and a pressure p.sub.2 results on the outflow side. A pressure difference Δp=p.sub.2−p.sub.1 can be calculated therefrom. This pressure difference and a media flow moved by the impeller have a defined dependence which is shown by way of example in the diagram according to FIG. 3 as a solid line. This fan forms the starting point for the exemplary embodiments of a fan according to the disclosure described hereinafter.

[0061] A first exemplary embodiment of a fan according to the disclosure is shown in FIG. 2. The fan 1 is constructed similarly to the fan shown in FIG. 1. The motor shaft 4′ of the present fan 1 comprises a feedthrough 9, which connects an opening on a front end of the motor shaft 4′ to an opening on the opposite front end of the motor shaft 4′. The feedthrough 9 is formed as a central bore, so that the motor shaft 4′ is a hollow shaft. In this way, a pressure p.sub.A results at the front end of the motor shaft 4′ facing away from the inflow side 5, which corresponds to the pressure p.sub.1 on the inflow side 5. The region having pressure p.sub.A can form a first region 10 in the meaning of the present disclosure.

[0062] In order that a pressure equalization does not occur, a bulkhead 11 is arranged in the electronics housing 8, which is fastened on a printed circuit board 12 of the motor electronics or directly on the base of the electronics housing. In this way, on the one hand, dirt and moisture is prevented from entering the electronics housing from the inflow side. On the other hand, a subdivision results due to this bulkhead 11, which separates the first region 10 from a second region 13. The bulkhead 11 and the printed circuit board 12 together prevent a pressure equalization between the regions 10 and 13 having the pressures p.sub.A or p.sub.B, respectively.

[0063] In the second region 13, a (static) pressure p.sub.B results which corresponds to the outflow-side pressure p.sub.2. These pressures p.sub.A and p.sub.B are measured by a first and a second absolute pressure sensor 14, 15, wherein the two absolute pressure sensors are each arranged on the printed circuit board 12 of the motor electronics in FIG. 2. An actual pressure difference Δp* results according to Δp*=p.sub.B−p.sub.A. This actual pressure difference Δp* also has, like the pressure difference Δp, a dependence on the volume flow moved by the fan. This relationship is shown as a dashed line in FIG. 3. It can be seen that both illustrated pressure characteristic curves (solid and dashed lines) are approximately proportional to one another. Moreover, both pressure characteristic curves, at least in the relevant illustrated region, are a strictly monotonously decreasing function of the volume flow. Therefore, the pressure characteristic curve Δp* (at least in this characteristic curve region) may be used to determine a volume flow and/or a mass flow of a medium moved by the fan. This shows that using the fan according to the disclosure, a pressure difference measurement can be measured locally in the region of the motor to form a system for determining the volume flow or the mass flow in operation compactly and locally in the region of the motor, without electrical lines or hoses having to be led away from the motor. If the pressure difference Δp* is used, only a calibration characteristic curve with respect to the corresponding local pressure difference Δp* has to be stored on the fan. Density and speed dependencies are to be treated here as already described at another point.

[0064] FIGS. 4 and 5 show two possible arrangements of a first absolute pressure sensor 14 in an enlargement, wherein the enlargement shows an embodiment similar to FIG. 2. In FIG. 4, the first absolute pressure sensor 14 is arranged—as in FIG. 2—on the printed circuit board 12 of the motor electronics. The bulkhead 11 is formed by a hollow-cylindrical component, for example made of plastic. In FIG. 5, the first absolute pressure sensor is arranged directly opposite to the electronics-side front end of the motor shaft 4′. The cover surface of the bulkhead 11 can be formed for this purpose by a printed circuit board 16, which can be connected by means of a cable 17 (for example a ribbon cable) to the printed circuit board 12 and thus to the motor electronics.

[0065] FIG. 6 shows a second exemplary embodiment of a fan 1′ according to the disclosure. In this exemplary embodiment, the motor shaft 4″ is only formed in parts as a hollow shaft. A feedthrough 18 connects an opening at a front end of the motor shaft 4″ to an opening on a long side of the motor shaft 4″. The feedthrough 18 is formed by a central bore extending approximately up to the long-side middle of the motor shaft 4″ and by a transverse bore. The front end of the motor shaft 4″ having the opening to the feedthrough 18 is oriented on the inflow side 5. A pressure equalization can thus result between the inflow side 5 and a bearing tube 19. In this way, the first region 10 in the meaning of the present disclosure is formed in the bearing tube 19 and a pressure p.sub.A results there. This pressure p.sub.A can be measured, for example, by a sensor arrangement 20, which is inserted into the bearing tube 19 and is described in detail in DE 10 2018 211 833 A1. This sensor arrangement 20 can comprise a first absolute pressure sensor 14, which measures the pressure p.sub.A. Since the bearings 21 at the two ends of the bearing tube 19 do not prevent a pressure equalization of the bearing tube 19 and are permeable, a bulkhead 11 is also arranged in this exemplary embodiment, which separates the first region 10 and a second region 13 formed in the electronics housing 8. It is also conceivable in other embodiments that no bulkhead is formed and bearings are used which prevent a pressure equalization. A second absolute pressure sensor 15 can measure the pressure p.sub.B prevailing in the second region 13.

[0066] A very similar embodiment of a fan according to the disclosure is shown in FIG. 7. In contrast to FIG. 6, in the fan 1.sup.ii, no sensor arrangement 20 is present in the bearing tube 19. Instead, a differential pressure sensor 22 is used. A first fitting, which offers access to a first sensor surface (not shown), is connected via a hose 23 and through the bulkhead 11 to the first region 10, so that the pressure p.sub.A of the first region 10 is applied to this first sensor surface, in particular if a pressure equalization is possible through the electronics-side bearing 21. A second fitting, which offers access to a second sensor surface (not shown), is open toward the interior of the electronics housing 8, so that the pressure p.sub.B inside the electronics housing 8 and thus inside the second region 13 is applied to this second sensor surface. In this way, the differential pressure sensor 22 can measure the actual differential pressure difference Δp*.

[0067] FIG. 8 shows the electric motor 2.sup.iii of a third exemplary embodiment of a fan according to the disclosure. Similarly as in the first exemplary embodiment according to FIG. 2, the motor shaft 4′ of this electric motor 2.sup.iii is formed as a hollow shaft. However, no bulkhead is present in this exemplary embodiment, so that a pressure p.sub.A results in the electronics housing 8, which corresponds to the pressure on the inflow side 5. Therefore, in this exemplary embodiment a first region 10 in the meaning of the present disclosure is formed in the electronics housing 8. The second region 13 is formed in this exemplary embodiment outside the electric motor 2.sup.iii, namely near the outer surface of the electronics housing 8. A differential pressure sensor 22, which is arranged on a printed circuit board 12 of the motor electronics, measures the actual pressure difference Δp*. A first fitting of the differential pressure sensor 22 is left open here toward the interior of the electronics housing 8, so that the pressure p.sub.A of the first region 10 is applied to a first sensor surface. The second fitting of the differential pressure sensor 22 is connected using a hose or duct 23 through a wall of the electronics housing 8 to the second region 13. In this way, the differential pressure sensor 22 also measures a differential pressure in this exemplary embodiment Δp*, which is suitable for determining a volume flow and/or a mass flow of a medium moved by the fan.

[0068] FIG. 9 shows an electric motor 2.sup.iv of a fourth exemplary embodiment of a fan according to the disclosure. A differential pressure sensor 22 detects an actual pressure difference Δp*, wherein a first sensor surface of the differential pressure sensor 22 detects a pressure p.sub.A and a second sensor surface detects a pressure p.sub.B. The first region 10 is formed in the interior of the electronics housing 8. A connection to the inflow side 5 results via a pressure duct 28, for example in the form of a groove. In one possible embodiment, the pressure duct 28 leads from the interior of the electronics housing 8 through the stator 27 into a region near an air passage 25. The pressure p.sub.A or a value that can be correlated thereto is made accessible to the first sensor surface of the sensor 22 through the air passage 25, for example, embodied as a condensed water hole or cooling opening. It is of secondary importance here whether the pressure duct 28 is applied directly in the immediate vicinity of the air passage 25, or an arbitrary region of an air gap 26 is attached. It is solely important that the tapped pressure p.sub.A correlates with the pressure p.sub.1 of the inflow side 5. For the sake of completeness, it is to be noted that in embodiments in which the rotor housing 24 of the motor 2 faces toward an outflow side 7 instead of the inflow side 5, the regions for pressures p.sub.1 and p.sub.2 or p.sub.A and p.sub.B occur exchanged with one another with respect to the motor 2.

[0069] FIG. 10 shows a variant of an electric motor 2.sup.v of the exemplary embodiment according to FIG. 9. A pressure duct 28 through the rotor 27 of the electric motor 2.sup.v is also used here. However, the first sensor surface of the differential pressure sensor 22 is connected directly via a hose 23 to the pressure duct 28.

[0070] Reference is made to the general part of the description and to the appended claims with respect to further advantageous embodiments of the fan according to the disclosure, the electric motor according to the disclosure, and the method according to the disclosure to avoid repetitions.

[0071] Finally, it is to be expressly noted that the above-described exemplary embodiments are used solely to explain the claimed teaching, but do not restrict it to the exemplary embodiments.

LIST OF REFERENCE NUMERALS

[0072] 1 fan [0073] 2 electric motor [0074] 3 impeller [0075] 4 motor shaft [0076] 5 inflow side [0077] 6 inlet nozzle [0078] 7 outflow side [0079] 8 electronics housing [0080] 9 feedthrough [0081] 10 first region [0082] 11 bulkhead [0083] 12 printed circuit board of the motor electronics [0084] 13 second region [0085] 14 first absolute pressure sensor [0086] 15 second absolute pressure sensor [0087] 16 printed circuit board for sensor [0088] 17 cable [0089] 18 feedthrough [0090] 19 bearing tube [0091] 20 sensor arrangement [0092] 21 bearing [0093] 22 differential pressure sensor [0094] 23 hose [0095] 24 rotor housing [0096] 25 air passage [0097] 26 air gap [0098] 27 stator, winding [0099] 28 pressure duct