GB2403511A

GB2403511A - Twin fan arrangement with changeover flap

Info

Publication number: GB2403511A
Application number: GB0322577A
Authority: GB
Inventors: Peter John Bayram
Original assignee: Individual
Current assignee: Individual
Priority date: 2003-06-11
Filing date: 2003-09-26
Publication date: 2005-01-05
Anticipated expiration: 2023-09-26
Also published as: GB0313468D0; GB2403511B; GB0322577D0

Abstract

A twin fan arrangement includes duty and standby centrifugal fans 2, 3, which are orientated at an angle to each other such that the normal direction of discharged air flow from the fans would cross. The arrangement includes flaps 4, 5 which, together with a discharge duct 8, enable air flow to expand as it is discharged from the duty fan 2. The arrangement of the fans is intended to allow them to be situated such that, in operation, their fan/motor shafts have a horizontal orientation, which is said to have space saving and bearing choice benefits. Sidewalls of the duct 8 may include streamlined, aerofoil-shaped, curved sections (10 figure 2). The flaps 4,5 may form a v-shaped changeover flap, which may include a hinge 6 and which may also include streamlined, aerofoil-shaped, sections.

Description

ANGLED DUTY f 5TOBY SIESED CENTRIFUGAL TW I -FAN UN I rs This invention

relates to a method of siaesinq together two (hi, duty and standby. double width double inlet. centrifugal fans for the express purpose of operation in conjunction with an air pressure operated autochangeover flap in such a way that static pressure regain is generated to the flow of discharge air from the duty fan, and positive closure is provided at the outlet of the standby fan. Sit.able flab. arrangements are detailed in Patent Application No: LBOi848..

Conventional Diapered centrifugal twin-fans are arrar,ged such that the fans are conjoined at the 'top' external face of the fan case and that the faces of the fan discharge outlets lie in the same (usually vertical) plane and next to each other' such that the fanJmotor shafts are vertical. With fans of thiE configuration there is no gravitational effect on the rotary of an air pressure operated autochangeover flap.

Siamesed twin-fans in the conventional configuration have vertical fanJmotor shafts that, therefore, precludes the use of plain bearing supported shafts since the spacerflateral washers at the bearings wi}1 fail when subjected to the force of the weight on the shaft of the fanJeotor, will then result in seizure of the bearing. In the case of deep groove ball bearing supported shafts consideration must be made to the change in loading on the top bal} bearing when the shaft is in the vertical, and this could require that the bottom bearing be secured with adhesive and an appropriate spring washer be added to the top bearing to preclude possible ball ship.

Also, coventional siamesed twin-fan units have relatively deep casings since airflow clearance space requires to be provided above and below the centrifugal fans, and such depth can pre- clude their possible use in (shallow) ceiling voids.

According to the present invention there is a method for the siamesing of cutyJstandbv double wide,, double inlet centr,f:g1 fans with horizontal fan st aft s that. thereby facilitates the use of plain bearing fansJmotors and standard deep groove tall bearing fansJmotors whether' no not. the motors are et.erna} rotor type or integral rotor type. Also. this.ethod er,ab}es

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the rovisior of the shallowest Possible unit casing.

specific embodiment of the invention Fill now oe descr.oed by way of example with reference to the accompanying drawing in which: Fiqure 1 shows in plan view a direct drive twin-fan. duty and standby, air handling unit arranged for dusted connection to the inlet and outlet spigots Referring to the drawing the twin-fan system comprises an Fir handling unit case 1 containing one (i' duty' c and one (' standby direct drive double width double inlet centrifugal fans mounted at a 30 degree angle relative to each other and siamesed together at the fan discharge edges. The static pressure regain autochangeover flap system within the air handling unit case comprises two () flaps 4 5 joined to- gether at an inclusive angle of 45 degrees and complete with a freely moving binge with one tl) blade of the flap 5 set at a diverging angle of 15 degrees from the direction of normal airflow from the duty fan 1. The airflow from the duty fan fan 1 diverges such that the discharge velocity pressure reduces and similarly the static pressure increases (less an efficiency loss factor), .e. their is static pressure regain.

The air handling unit is shown connected to discharge duct- work and extract ductwork 9' and it is the frictional resist- ance to the flow of air through these ducts that generates a negative (-we) pressure at the duty fan inlet c' and a posi- tive {+ve) pressure at the duty fan 2 outlet. It is this pressure difference that holds the flap blade 4 shut and that also overcomes the lifting effect of the diverging airflow across flap 5.

Claims

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1 twin-fan unit comprising two À) duty/standby centrifugal fans with horior.tal fan shafts Diapered together at the fan discharge spigots and angled relative to each other such that the noreal direction of the flow of discharge air from each fan is convergent and such that the flow of discharge air from the duty fan is divergently expanded both by the respective side of the common discharge duct and the respective side of one half of the changeover flap.

twin-fan unit as claimed in Clain I wherein the vertical sides of the common discharge duct have aerofoilistreamlining section additions 10 at, or close to the fan discharge outlets generally as illustrated by Figure 2, or wherein the respect- ive duct sides are curved to an aerofoil/strealine shape, twin-fan unit as claimed in Claims wherein the fans are indirectly Diapered via duct extensions of the fan dis- charge outlet spigots.

4 twin-fan unit as claimed in any preceding Claim wherein the outer faces of each half of the 'v' shaped changeover flap are aerofoilJstrealine shaped in full, or in part and with the leading edge located at, or close to the hinge of the flap.

twin-fan unit as claimed in any preceding Claim wherein the respective half of the changeover flap is not necessarily at a divergent angle to the flow of discharge air from the duty fan.

6 h twin-fan unit substantially as described herein with reference to the Figure 1 accompanying drawing.

Amendments to the claims have been filed as follows C L 1 M S 1 twin-fan unit comprising two () horizontal discharge, duty and standby, double width and double inlet centrifugal fans having horizontal fan shafts siauesed together at the fan dis- charge spigots and angled relative to each other such that the normal direction of the flow of discharge air from each fan would be convergent and such that the flow of discharge air from the duty fan is divergently expanded via the respect- ive side of the common discharge duct and the respective side of one half of the changeover flap being at a divergent angle relative to each other.

twin-fan unit as claimed in Claim 1, wherein the vertical sides of the cocoon discharge duct have aerofoilJstreaelining lift generating section additions 10 at, or close to the fan discharge fan outlets, generally as illustrated by Figure 2, or wherein the respective duct sides are curved to a convex aero- foilistreaeline shape thee UK Patent Application 6B 395 5Z4 - Static pressure regain foil for diverging duct).

twin-fan unit as claimed in Claims 1 2, wherein the fans are indirectly Biassed via short duct spigot extensions of the fan discharge outlet spigots, as may be practically necessary for construction purposes.

4 twin-fan unit as claimed in any preceding claims wherein the respective half of the changeover flap is not necessarily at a divergent angle to the flow of discharge air fro. the duty fan, i.e. parallel or slightly convergent twin-fan unit substantially as described herein with reference to Figures 1 and 2 of the accompanying drawings.