FR3055106A1 - LIQUID INJECTION DEVICE FOR ROTATITF DISC ATOMIZER - Google Patents

Abstract

The present invention presents an improvement for the liquid supply of rotary jet atomizers: this improvement makes it possible, thanks to a precise dimensioning and positioning of the liquid supply, to prevent the liquid from coming into contact with the fluid. drive motor axis and reduce or even remove the sealing device at this level.

Description

055 106

70460 ® FRENCH REPUBLIC

NATIONAL INSTITUTE OF INDUSTRIAL PROPERTY © Publication number:

(to be used only for reproduction orders)

©) National registration number

COURBEVOIE © IntCI ⁸ : B 05 B 3/10 (2017.01)

PATENT INVENTION APPLICATION

A1

©) Date of filing: 20.08.16. (© Applicant (s): SPRAI— FR. (© Priority: @ Inventor (s): CHICHEPORTICHE JEAN MARC, RENAUDEAUX JEAN PIERRE and ZAINOUN JEAN (43) Date of public availability of the BAPTIST. request: 23.02.18 Bulletin 18/08. ©) List of documents cited in the report preliminary research: Refer to end of present booklet (© References to other national documents ©) Holder (s): SPRAI. related: ©) Extension request (s): (© Agent (s): SPRAI.

(o4) LIQUID INJECTION DEVICE FOR ROTATITF DISK ATOMIZER.

(© The present invention presents an improvement for the liquid supply of atomizers with rotary jets:

this improvement makes it possible, thanks to precise dimensioning and positioning of the liquid supply, to prevent the liquid from coming into contact with the axis of the drive motor and to reduce or even eliminate the sealing device at this level.

FR 3 055 106 - A1

217093080270000160811 i

The present invention relates to an improvement made to liquid spraying systems by rotating discs. These systems are composed of a disc, bowl or other object with symmetry of axial revolution or not called below under the generic term of disc rotated by a generally electric motor.

The disc, bowl or other object with symmetry of axial revolution is supplied with liquid by one or more injection devices. The liquid spreads over the surface of the disc and dissolves in droplets at its periphery or near its periphery. An important element of these spraying systems is the supply of liquid to the disc. This feeding must be done in the center of the disc or near the center to obtain a good quality of spatial homogeneity and particle size dispersion on the edges of the disc, but must not risk damaging the engine due to infiltration, in particular along the axis of the engine.

This improvement relates to the liquid injection device.

It is known that the supply of liquid to the disc is generally done by one of the following techniques:

In a first method (FIG. 1), the face opposite to the motor (1) is fed, rotating the disc (2), bowl or other object with symmetry of axial revolution by a tube (3) having the same axis of symmetry as the motor rotor. This technique generally requires that the tube and the motor be joined by a junction (4) which will necessarily be on the path of the droplets emitted by the disc. This results in areas of liquid accumulation on the junction and dripping which are generally troublesome for the user. To avoid these problems, it is necessary to supply liquid to the face of the disc, bowl or other object with symmetry of axial revolution adjacent to the motor. One method (Figure 2) is then to use a hollow axis of rotation (1) opening onto the surface of the disc (2) opposite the motor and to feed this disc from the hollow axis. This technique works well provided that the motor has a sufficiently large axis of rotation.

When using micro motors, which typically have axis diameters of the order of a millimeter, this technique cannot be used and the disk is supplied with liquid by an annular device as shown in FIG. 3. liquid arrives via a pipe (4) in an annular chamber (5) surrounding the axis of rotation of the motor (1) and opening onto the surface of the disc (2). Adjacent to the engine (1). It is therefore necessary to protect the motor very well from liquid infiltration by fitting a perfectly watertight rotary joint. This technique, which is quite delicate to implement practically taking into account manufacturing tolerances, involves a cost at the manufacturing level and absorbs a non-negligible part of the engine power.

The present invention proposes a new method of supplying liquid, not respecting the symmetry of revolution of the system, usable whatever the diameter of the disc,

217093080270000160911 simple to implement, allowing to obtain a uniformity and a particle size dispersion of the aerosols equivalent to that obtained with a symmetrical supply and not requiring a perfect sealing of the engine. This new method has a definite advantage over those previously described. It is known in fluid mechanics that the injection of the liquid on the disc constitutes a singularity of the flow and that any singularity introduced into a flow, for example an abrupt or progressive widening or a change of direction, locally disturbs the flow upstream and downstream and requires a certain length of flow to attenuate and disappear, the greater the greater the disturbance. It is known that this length depends mainly on the shape of the singularity and, for free surface flows, Reynolds and Froude numbers. It is also known that the better the singularity accompanies the flow, the less it disturbs it. This is how a contoured elbow with a large radius of curvature disturbs the flow much less than a right angle elbow.

The present invention is based on these principles and on the knowledge of the flows on the rotary discs to bring a significant improvement to the feeding devices. In the case of a flow on a rotating disc with an ideal point injector centered on the axis, it is known that the three components of the velocity field, Vr speed along a radius of the disc, Vt velocity tangential to the disc , and Vz speed perpendicular to the plane of the disc obey the qualitative law Vz "Vr" Vt, typically the axial speed is 10 times smaller than the radial speed which is itself ten times smaller than the tangential speed which can be approached by the value Vt = m ² r. It is also known that the pressure on the surface of the disc is maximum at the center and decreases to atmospheric pressure at the periphery.

This knowledge makes it possible to say that the supply which disturbs the flow the least is constituted by one or more injectors such that the components of the speed at the outlet of the injector or injectors are as close as possible to the components of the speed of the flow that would exist on the disc with an ideal point injector centered on the axis.

FIGS. 4 and 5 describe an embodiment given by way of example. The injector is a cylindrical tube (6), the axis of which is oriented according to the vector U defined by (i /) = a (ur) + β (μθ) + y (uz) where oc = arctan ^, β = ^ - a - y (9) close to ür is the unit vector along the radius of the disc, ud is the unit vector tangential to the disc and üz is the unit vector along the axis of rotation of the disc. The end (7) of the tube (6), bevelled parallel to the surface of the disc, is placed at a distance from the disc corresponding to the height of the free surface of the liquid at the place where the end is placed, ie between 10 micrometers and 10 mm according to the flow rates and at a distance from the axis of rotation of the order of magnitude of R / 10 where R is the radius of the disc. The cross-section S of the tube at the level of the injector is such that the rate of flow in the duct is as close as possible to the speed of the flow at the level of Γ injection and the rate equal to the desired rate. In this system the liquid always arrives on the face of the disc (2) adjacent to the motor (1), but the slight disturbance created by the injection of liquid prevents it from going up to the axis of the motor (1) when it is rotating.

It should be noted that the tube described in the example is cylindrical, but that it can also be convergent or divergent

According to another embodiment given by way of example, the supply of liquid to the disc can be carried out from several injectors, preferably regularly distributed around the axis of rotation, each injector obeying the same geometric conditions described in the first embodiment. The cross section S of each tube at

- 15 the injector is such that the delivery speed in the duct is as close as possible to the flow speed at the injection level and the flow rate of each injector equal to the total desired flow divided by the number of injectors .

If these conditions are perfectly respected, when the disc is rotating, the injected liquid 20 cannot go upstream until it reaches the axis of rotation. There is no longer any need to seal the motor rotation axis.

This improvement constitutes a definite advantage compared to the devices lacking this improvement.

The present invention relates to the device (s) for injecting the liquid onto the rotary disc 25 located on the same side as the motor and off-center with respect to the axis of rotation of the disc.

21709308027000016

217Ο93Ο8Ο27ΟΟΟΟ161111

Claims (5)

5 1. System generating an aerosol, of the rotating disc atomizer type, comprising a flat disc or object with symmetry of axial revolution or not put at high speed of rotation by a motor, a liquid supply device characterized in that the feed device is located on the same side of the disc as the motor and offset from the disc rotation tax 10 2. An aerosol generating system, of the rotating disc atomizer type, comprising a flat disc or object with symmetry of axial revolution set at high speed of rotation by a motor, several devices for supplying liquid, characterized in that the devices for power supply are located on the same side of the disc as the motor and offset from the disc rotation tax. 3. An aerosol generating system, of the rotating disc atomizer type, comprising a flat disc or object with symmetry of axial revolution or not set at high speed of rotation by a motor, one or more liquid supply devices, depending on the points 1 or 2 characterized in that the supply device is a tube the end of which has a parallel bevel a 20 flat disc or parallel locally to the object with symmetry of axial revolution or not. 4. An aerosol generating system, of the rotating disc atomizer type, comprising a flat disc or object with symmetry of axial revolution set at high speed of rotation by a motor, a 25 liquid supply device, according to point 3 characterized in that the tube or tubes make an angle close to 90 ° with the normal to the disc. 5. An aerosol generating system, of the rotating disc atomizer type, comprising a flat disc or object with symmetry of axial revolution set at high speed of rotation by a motor, a 30 liquid supply device, according to point 3 characterized in that the tube or tubes have a total cross section such that the delivery speed is close to the speed of rotation of the disc at the injection level. 1/4