Driving device for providing assisted ventilation

Abstract

The driving device for providing assisted ventilation comprises an air inlet (15), an impeller (7) provided with blades (8) rotatably driven by a motor (6), and an air outlet (5), the rotation of said impeller (7) being caused by the air circulation through a duct (4) from the air inlet (15) to the air outlet (5), wherein said blades (8) of the impeller (7) are flexible, vibrating at least one of its ends by the thrust caused by said circulating air.

It reduces noise to improve user comfort.

Claims

1. Driving device for providing assisted ventilation, comprising an air inlet (15), an impeller (7) provided with blades (8) rotatably driven by a motor (6), and an air outlet (5), the rotation of said impeller (7) being caused by the air circulation through a duct (4) from the air inlet (15) to the air outlet (5), characterized in that said blades (8) of the impeller (7) are flexible, vibrating at least one of their ends by the thrust caused by said circulating air.

2. The device according to claim 1, wherein said blades (8) are curved.

3. The device according to claim 1, wherein the end of each blade (8) closest to the axis of rotation of the impeller (7) is fixed with respect to the impeller (7) and the end of each blade (8) furthest from the rotation axis of the impeller (7) is the end that moves due to the vibration caused by the circulating air.

4. The device according to claim 1, which also comprises accelerometers mounted at a point close to the motor attachment (6) and/or on the impeller (7).

5. The device according to claim 1, which also comprises a motor angle gauge (6), which measures the angle of inclination of the motor (6) during the rotation of the impeller (7).

6. The device according to claim 1, wherein said duct (4) comprises a plurality of internal cavities (12).

7. The device according to claim 6, wherein each internal cavity (12) comprises at least one support column (13).

8. The device according to claim 1, wherein said air inlet (15) comprises a plurality of air directing vanes (16).

9. The device according to claim 8, wherein s each of said vanes (16) has a wavy shape.

10. The device according to claim 1, wherein said duct (4) comprises a partition (17) to produce vibrations induced by vortexes.

11. The device according to claim 10, wherein said partition (17) is placed at the end of the duct (4) closest to the air outlet (5).

12. The device according to claim 1, which also comprises a first microphone (20) to detect the sound produced by the air inside the channel (4), said first microphone (20) being located in a housing provided with a hole (23) in communication with the channel (4).

13. The device according to claim 1, which also comprises a second microphone (21) for detecting the sound produced by the air inside the device, said second microphone (21) being located in a closed housing.

14. The device according to claim 12, wherein said hole (23) is conical in shape.

15. The device according to claim 12 or H, wherein a circular groove (24) is arranged around said hole (23).

16. The device according to claim 12, which also comprises a second microphone (21) for detecting the sound produced by the air inside the device, said second microphone (21) being located in a closed housing.

17. The device according to claim 14, wherein a circular groove (24) is arranged around said hole (23).

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0042] For a better understanding of what has been stated, some drawings are attached in which, schematically and only as a non-limiting example, a practical case of embodiment is represented.

[0043] FIG. 1 is a perspective view of a driving device in accordance with the present invention;

[0044] FIG. 2 is a cross-sectional elevation view of the driving device of FIG. 1;

[0045] FIG. 3 is a cross-sectional elevation view, similar to FIG. 2, showing the internal cavities for reducing air turbulence;

[0046] FIG. 4 is a perspective view of the air inlet to the device, with its upper part removed to show the shape of the blades of said inlet;

[0047] FIG. 5 is a sectional elevation view of the driving device according to the present invention, wherein the partition placed inside the air duct can be seen;

[0048] FIG. 6 is a longitudinal section plan view of the driving device according to the present invention, wherein the impeller with its blades is shown;

[0049] FIG. 7 is a sectional view of the part of the driving device according to the present invention wherein the motor and the impeller are located;

[0050] FIG. 8 is a block diagram of the active noise cancellation system that includes the driving device according to the present invention;

[0051] FIG. 9 is a sectional elevation view of the part of the device where the microphones are located; and

[0052] FIG. 10 is a sectional perspective view of a microphone placed inside its housing.

DESCRIPTION OF A PREFERRED EMBODIMENT

[0053] As shown in FIGS. 1 and 2, the driving device for providing assisted ventilation according to the present invention comprises a housing 1 provided with an upper cover 2 and a lower cover 3, said housing 1 defining inside a channel 4 for conveying air, which air is provided to a user from an inlet 15 to an outlet 5.

[0054] Furthermore, the driving device according to the present invention comprises inside a motor 6 that rotatably drives an impeller 7 provided with blades 8, the rotation of which causes air circulation.

[0055] This driving device also comprises a first and second plates 9, 10 for mounting electronic components to guarantee the correct operation of the driving device.

[0056] Part of the noise produced by this driving device is due to the rotation of its mechanical assembly, that is, the motor 6 and the impeller 7.

[0057] Consequently, to reduce noise, vibration reduction by balancing in two or more rotating planes is necessary. This balancing is carried out in three ways, by separating the motor 6, the impeller 7 and then the motor 6 and impeller 7 assembly. This balancing is carried out by adding or removing material, for example, by means of cavities.

[0058] In particular, the reduction of vibrations by balancing in one or more planes in rotation is carried out by applying successive approximations towards a more balanced system, obtaining the axial buckling and vibration components of both the motor 6 and the impeller 7.

[0059] Obtaining these components is carried out, for example, by means of two three-axis accelerometers far apart and attached to the structure that holds the motor 6. Preferably, a rotation angle gauge is also used, which measures the rotation of the motor's output shaft 6.

[0060] By solving the components of each force by linear combination of these quantities and modifying the centers of masses of the motor 6 and of the impeller 7, by adding or subtracting material, the correct balance is achieved, avoiding or reducing a source of noise.

[0061] Another source of transmission of vibrations and noise are the fasteners between the different components that make up the driving device according to the present invention.

[0062] To avoid vibrations, the different components that make up the device must be held together, minimizing the transmission of movement from moving parts to static parts.

[0063] For this, said components are fixed at the points where the vibration modes present minimum amplitude at the typical frequencies (with greater amplitude) present in the noise source at different working regimes. To know these values, interferometric measurement is used, with or without laser, sand on the surface, or numerical simulation.

[0064] Another source of noise in the driving device according to the present invention is the turbulence of the air itself when it circulates abruptly in the different points of the cavity 11 where the impeller 7 is housed, the noise being transmitted through the air towards the duct 4.

[0065] To avoid this transmission, internal cavities 12 are arranged in said duct 4, wherein a degree of vacuum will be practiced. These internal cavities are preferably arranged around the acoustic vibration sources to isolate them from the outside of the device.

[0066] In addition, to prevent the structure of the duct 4 from being crushed by air pressure, support columns 13 are added at the points where the vibration modes may have minimum amplitude at the typical frequencies (with greater amplitude) present at the noise source at different work regimes.

[0067] To know these points, interferometric measurement with or without laser, sand on the surface or numerical simulation can be used. Air jet ducts 14 can also be added, which can also collect waste from 3D printing manufacturing.

[0068] In FIG. 4 vanes 16 are shown in perspective and are formed in the air inlet 15 to the driving device. These vanes 16, which are static, guide the incoming air flow, reducing the level of rotational change and, therefore, the acoustic wave generated at the air inlet 15.

[0069] As can be seen in this FIG. 4, each vane 16 preferably has a spiral shape, although it could have any suitable shape.

[0070] Furthermore, to favor the appearance of vortex-induced vibrations (“Vortex Induced Vibrations”) in a narrow frequency range, the driving device according to the present invention also comprises a partition 17 placed inside the duct 4. As can be seen in FIG. 5, said partition 17 is preferably curved and is located at the end of the duct 4 closest to the outlet 5.

[0071] The aim of vortex-induced vibrations to be in a narrow frequency range is to optimize their active cancellation, as will be described later.

[0072] To reduce the noise generated, it is also important to smooth the wave fronts generated by the blades 8 of the impeller 7, shown in greater detail in FIG. 6. For this, said blades 8 are flexible, and vibrate on a push-pull basis with the wave generated reducing the noise generated.

[0073] In particular, said blades 8 are curved and their end closest to the axis of rotation of the impeller 7 is fixed, the end farthest from the axis of rotation of the impeller 7 being the one that moves by virtue of the flexible nature of the blades 8 during the vibration.

[0074] When the blades 8 of the impeller 7 vibrate with respect to the impeller 7, with respect to the speed of the blades 8 with respect to the impeller 7, there are times when:

[0075] the speed is positive and is added to the tangential speed of the impeller 7,

[0076] the speed is neutral and the blades 8 move at the same speed as the impeller 7, or

[0077] the speed is negative and is subtracted from the tangential speed of the impeller.

[0078] When it is desired to silence the impeller 7, the aim is to achieve that the frequencies of oscillation of the blades 8 be multiples of the speed of rotation of the impeller 7 plus a small phase shift, not close to 180 degrees. In this way, the blades 8 reduce their tangential speed, just at the moment of passing in front of the exit vertex 18, in such a way that the transient wave generated at that moment is reduced.

[0079] The oscillation of the blades 8 is maintained by virtue of the energy they absorb in the form of bending at the moment when the air pressure rises sharply at the outlet vertex 18. This energy, instead of generating a sudden transient with a plurality of harmonics, gradually dissipates in the form of a decreasing oscillation at the typical oscillation frequency of the blades 8 and over a longer time than the sudden pressure impact would suppose, therefore it supposes a lower noise level.

[0080] The damped wave of known frequency is easily eliminated by an active noise cancellation system with the use of microphones and speakers.

[0081] Likewise, the superposition of the out-of-phase waves of each of the different blades 8 of the impeller 7 supposes a subtractive sum, which further reduces the effect of the waves generated. In this way, the frequency of rotation of the impeller 7 will be gradually adjusted until a minimum of sound emission is achieved.

[0082] To further reduce the vibrations of the vibrating components, in particular the motor 6 and the impeller 7, elastic means integrated in the holding structure of these components can be included.

[0083] For example, as shown in FIG. 7, said elastic means may be formed by grooves 19 arranged alternately in the part of the housing 1 which is arranged between the motor 6 and the impeller 7.

[0084] The driving device according to the present invention also comprises an electronic active noise cancellation system, which is mounted on the first and/or second plates 9, 10.

[0085] Said electronic system improves and optimizes active noise cancellation, for example, through the use of tables of cancellation parameters or filter coefficients, indexed or calculated from the angular speed and/or the pressure and/or the flow that supplies the device, to accelerate the convergence process faced to a variation in the working regime of the impeller 7.

[0086] Said electronic system is shown in FIG. 8, comprising a main microphone 20, an error microphone 21 and a control speaker 22.

[0087] The sound from the main microphone 20 is filtered through a series of parameters and characterization provided from a control. Furthermore, the filtered sound and the sound from the error microphone 21 are applied an adaptive algorithm, which is known in the art, providing a signal to the control speaker 22 for active noise cancellation.

[0088] To improve active noise cancellation, one or more vibration measurement elements can be included to subtract the parasitic components of the solid vibration from the useful signal present in the air and measured by the microphones 20, 21 of the electronic system of active cancellation.

[0089] As shown in FIG. 9, one of these microphones 20 has a hole 23 in communication with channel 4, which captures the sound of channel 4 and the vibration of the housing 1, while the other microphone 21 only captures the vibration of housing 1.

[0090] If desired, hard, porous surfaces can be included around the noise pick-up microphones 20, 21 to reduce the acoustic effect of airflow in the vicinity of the pick-up point of the microphone 20, 21.

[0091] Auditory panels can also be included at the pickup point of the microphones 20, to move away the turbulence points from the area of auscultation, and also a mechanical isolation of the vibrations.

[0092] As shown in FIG. 10, a circular groove 24 may be formed arranged around the hole 23 of the microphone 20, which is funnel-shaped.

[0093] If desired, ultraviolet light can also be used inside the air channel 4 for disinfection and the use of an active Helmholtz cavity (with speaker).

[0094] Although reference has been made to a specific embodiment of the invention, it is clear to an expert in the field that the described driving device is susceptible to numerous variations and modifications, and that all the mentioned details can be replaced by other technically equivalent ones, without departing from the scope of protection defined by the appended claims.