GB2119438A

GB2119438A - Acoustic ventilation device

Info

Publication number: GB2119438A
Application number: GB08133686A
Authority: GB
Inventors: Stanley Arthur John Blyther; Richard James Turner
Original assignee: AIR DOMESTIQUE Ltd
Current assignee: AIR DOMESTIQUE Ltd
Priority date: 1981-11-09
Filing date: 1981-11-09
Publication date: 1983-11-16

Abstract

An acoustic ventilator has a fan 102, motor 103 and power supply means 105 mounted as a removable sub-assembly, for ease of servicing, from a ventilation unit, Fig. 2 (not shown). The mounting of the sub- assembly may include flexible mounting for noise control. Further, accurate mounting of removable labyrinth arrangement of baffles, e.g. (203), Fig. 2, may be achieved by using pre-formed slots in a back plate of the ventilation unit and connecting the baffles to them by deformable tags or lugs on the baffles. <IMAGE>

Description

SPECIFICATION Improvements to acoustic ventilation devices This invention relates to acoustic ventilation devices, and improvements to the construction thereof.

Acoustic ventilation devices provide a means of ventilating a room which has been insulated from noise-pollution by the use of double-glazing.

Clearly there is a requirement that any method of ventilation should encourage a free-flow of air, without admitting, or itself generating, noise.

Devices of the prior art suffer from one or more of the following disadvantages; they generate noise themselves, they have to be removed from the wall-mounting for repair, and they require careful calibration of the absorbing surfaces.

In accordance with a first aspect of the invention, there is provided an acoustic ventilation device. which comprises a removable sub-chassis bearing a fan, a motor and associated circuitry.

By mounting the impeller and its power-supply on a removable sub-chassis, an electrical fault may be correct by the rapid replacement of the defective sub-chassis, which may then be repaired without extended loss of ventilation or acoustic insulation.

Preferably, the sub-chassis is replaceable via a removable front panel without detachment of the acoustic ventilation device from its mounting, and the means of securing the removable sub-chassis are a plurality of flexible fixings.

By not requiring the detachment of the acoustic ventilation device from the mounting, usually upon a wall, the repair time is cut considerably, reducing both costs and inconvenience. The flexible fixings which secure the sub-chassis within the device, ensure that there is a reduction in the transmission of sound from the motor to the room being ventilated.

Conveniently, the labrynth of baffles, within the acoustic ventilation device, is secured to the backplate by means of tags or lugs which locate in preformed slots in the back plate.

The advantage of this method of construction is that the baffles are aligned precisely, in less time than in previous devices. The alignment of these baffles is crucial to the correct functioning of the device.

Furthermore, there may be provided one or more passages within the labrynth having a central partition defining at least two, unequal paths.

By causing the air-flow to be divided and taken by two paths, one of which is longer than the other, phase differences are found at the point where the flows recombine. These help to increase the sound reducing properties of the device.

The invention will be further described with reference to the accompanying drawings, in which:- Figure 1. is a schematic representation of the sub chassis showing the motor, fan and associated circuitry power -supply; Figure 2 is a schematic representation of the internal labrynth of the acoustic ventilation device and the locatioh of the sub-chassis, and Figure 3 is a schematic representation of the acoustic ventilation device showing the back plate and the means of securing the baffles of the internal labrynth.

Referring first to figure 1, the foam-covered plate 100 and the curved plate 104 with a foam covered upper edge, form a removable subchassis secured by screws which locate in four holes 101.The holes 101 are each provided with a rubber grommet and an internal sleeve forming a flexible mounting. This prevents the noise of the motor 103 and fan 102 being transmitted, through the sub-chassis, to the casing of the acoustic ventilation device.

The motor 103 may be of any convenient type.

In the preferred embodiment a split phase induction motor is employed. The associated circuitry will therefore vary with the particular requirements of the motor. In the preferred embodiment the power supply consists of variable resistor 105 and capacitor 107, connected to the motor through cable 108 and connector 1 06.

Electricity is supplied to the sub-chassis by the supply wires 109.

The fan 102 may be of any convenient type. In figure 1 it is envisaged as a drum rotor, being a cylindrical fan with blades, disposed axially, forming the cylinder walls.

The variable resistor 105 is located over a hole in the sub-chassis through which its control shaft runs.

Referring now to figure 2, the sub-chassis 200 is located in the case of the acoustic ventilation device 211 and secured by screws 201.

The acoustic ventilation device consists of a case 211 with a lid 207. All internal surfaces are provided with a layer of foam. The case is divided by a transverse wall 206 which separates intake and exhaust air flows.

Air is drawn into the device by the fan (see figure 1) and enters the intake labrynth at A. The air flow is divided by partition 203, this is also covered with a layer of foam. The air flow continues part by route B and part by route C, and is recombined at the grille 212 where it is discharged into the room being ventilated.

The overpressure in the room, as a result of the air discharged by the device, causes an exhaust flow through the second half of the labrynth. Air enters through the grille 202 and flows by route D, to the exhaust port 213.

The lid is secured by four screws locating in holes 210, 208 and is provided with a hole 207 which gives access to the control dial 205. This dial is mounted on the control shaft of the variable resistor and enables the speed of the fan to be varied.

Replacement of the sub-chassis 200 on failure of a component is accomplished by the removal of the lid 207 and the release of four screws 201.

The supply wires (109, see figure 1) may then be exchanged with those of a new unit which is secured by screws 201. At no time is it necessary to remove the acoustic ventilation device from its mounting, usually on a wall, to which it is secured by bolts locating in holes such as 213A.

Referring now to figure 3, the underside of the case 311 is shown. The ports 313, 303 are exhaust and intake respectively. The back plate 301 is provided with slots, in which tags 308 locate. The tags arise from the lower edge of the partitions of the internal labrynth (e.g; 203, see figure 2).

Simple inspection of the back plate 301, reveals whether or not the tags are correctly located, and hence that the partitions of the internal labrynth (e.g. 203 see figure 2) are correctly aligned to give maximum efficiency in sound absorption.

The advantages of the invention are more particularly, that there is provided an acoustic ventilation device which by virtue of its construction is more economically produced and rapidly repaired.

Various modifications may be made within the scope of the invention.

Claims

1. An acoustic ventilation device, which comprises a removable sub-chassis, bearing a fan, motor and power supply.

2. An acoustic ventilation device as claimed in claim 1 , from which the sub-chassis is removable without detachment of the acoustic ventilation device from its mounting.

3. An acoustic ventilation device as claimed in claims 1 or 2, in which the means of the securing the removable sub-chassis is by a plurality of flexible fixings.

4. An acoustic ventilation device as claimed in claims 1, 2 or 3, having a labrynth of baffles secured to the back-plate by means of tags or lugs which locate in slots in the back plate.

5. An acoustic ventilation device as claimed in claims 1,2, 3 or 4 in which there are provided one or more passages within the labrynth having a central partition defining at least two unequal paths.

6. An acoustic ventilation device substantially as hereinbefore described with reference to the accompanying figures 1,2 and 3.

7. An acoustic ventilation device having a back plate and a labyrinth of air flow directing baffles attached to the back plate by means of deformable tags or lugs passed through preformed slots in the back plate and turned over.

8. An acoustic ventilation device as claimed in claim 7, in which the baffles are covered in a foam material.

9. An acoustic ventilation device as claimed in claim 7 or 8, in which an air passage from a fan outlet to a discharge grille includes a baffle which divides the air passage into two paths of unequal length.