Air inlet means for air conditioning installations or the like

Abstract

This invention relates to an air conditioning system which includes an enclosed room having vertical wall means with an air inlet opening therein. Cooled air passing through the opening has one or two variable parameters which are its velocity and its temperature. Movable vanes are set in the inlet opening and the angle of inclination of the vanes is varied in a manner to avoid discomfort to occupants of the room by being subjected to cold drafts of air. Air temperature or air velocity sensing means are provided. Control means responsive to said sensing means are provided which varies the inclination of the vanes inversely relative to the sensed air temperature or sensed air velocity and (2) simultaneously varies the temperature of the air admitted to the room.

Description

The invention relates to an air inlet means, for air conditioning installations or the like, of which an inlet opening disposed substantially in a vertical plane is divided by vanes which impart a fixed inlet angle to the air stream, one parameter at least of the inlet air being variable. In air conditioning and ventilating installations the problem arises of the users of air conditioned or ventilated premises being troubled by draughts associated with the changing air. This applies to a greater extent, the higher the velocity or the lower the temperature of the air blown in. The longer the air blown in has to mix with the air in the room, the lower its velocity becomes, the more its temperature rises and the less unpleasant is any draught.

Efforts have therefore been made, by disposing the inlet opening above the level of the heads of people using the room and by the use of vanes in the inlet opening for fixing the air inlet angle, to cause the stream of air blown in to take a path such that it causes as little trouble as possible by draughts. It has been found, however, that when operating an air conditioning installation this flow path varies in an undesirable manner.

The object of the present invention is to provide an air inlet means of the initially stated kind in which simple measures ensure that the stream of air blown in follows a path which is subjected to considerably smaller troublesome variations during operation of the installation.

According to the present invention, this object is achieved by making the inclination of the vanes to the horizontal variable in dependence upon a parameter of the air blown in.

This solution is based upon the consideration that troublesome changes in the flow path are caused by changes in a parameter of the air blown in. By varying the inlet angle during operation of the installation, as proposed by the present invention, these troublesome changes can be wholly or partly compensated. In the most favourable case, the temperature and air distributed in the room can be substantially maintained even when a change occurs in the quantity of cooling air.

If a fairly large quantity of cooling air is to be discharged from the room into which it is blown, the temperature of the air blown in is generally reduced or its volume increased. The parameters mainly of interest in this case are therefore the temperature and the volume or velocity of the air blown in. When the temperature of the air blown in drops or its volume is reduced there arises the danger that air will flow prematurely into the actual zone where it is to dwell. This danger is eliminated by a regulating device which increases the inclination of the vanes when the temperature or volume of the inlet air drops.

In a preferred arrangement, a common signal generator controls both the parameter of the inlet air and the inclination of the vanes. In particular the common signal generator can be a thermostat which is fitted in the room having the inlet opening. In this way it becomes possible to avoid a control system which senses the parameter and then alters the inclination of the vanes in dependence thereon.

The inclination of the vanes is preferably variable by means of an adjusting device which is acted upon on the one hand by a pressure signal and on the other hand by an opposing spring. The pressure signal, which can be supplied for example by the vapour pressure of a thermostat having a liquid vapor filling, or particularly by a pneumatic system, produces in conjunction with the spring a specific inclination of the vanes. A particularly advantageous feature in this connection is that with the aid of the spring it is possible to match the required relationship between the change in the parameter and the change in the inclination of the vanes even if this relationship is not a linear one. In this case it suffices simply to use a spring having a corresponding non-linear characteristic curve.

The invention will now be described in greater detail by reference to an arrangement illustrated in the drawing, in which:

FIG. 1 is a diagrammatic illustration of an air conditioned room which has a normal air inlet means, and

FIG. 2 is a diagrammatic illustration of an air inlet means in accordance with the invention.

A room 1 is provided with an air supply duct 2 and an air discharge duct 3. A mixing unit 5 controlled by a thermostat 4 has an inlet duct 6 for warmer air and an inlet duct 7 for colder air (two duct system). The air entering the room 1 through an inlet opening 8 therefore has a temperature dependent upon the cooling requirements of the room.

It is possible to determine an optimum flow path which results in a user of the room 1 being exposed to virtually no draught at all from the air blown in, but which however results in the air blown in being distributed substantially uniformly in the zone where it is to dwell. A flow path along the line a in FIG. 1 for example has proved to be particularly favourable. The stream of air enters at one side wall of the room and the flow path centerline strikes the opposite wall at a predetermined distance above the floor. If the thermostat 4 then signals a higher room temperature and the temperature of the air to be blown in is reduced for this reason, the stream of air follows a path indicated by line b in FIG. 1, as a result of the higher specific weight of the colder air. This line deviates from the optimum flow path. In particular the cold air descends in the middle of the room into the desired zone of dwell.

As the arrangement in accordance with the invention illustrated in FIG. 2 shows, vanes 9 are fitted in the inlet opening 8 and these can be swung about horizontal shafts 10 in such a manner that their inclination to the horizontal, i.e. the angle .alpha. is altered. This angle, however, corresponds substantially to the inlet angle at which the air enters the room 1. The inclination of the vanes can be varied by an adjustment device which is acted upon on the one side by a pressure actuated piston 12 and on the other side by a spring 13 which applies force in the opposite direction. In the present case the thermostat 4 is formed as a throttle valve through which pressure from a pressure storage unit 14 is passed on the one hand to the mixing unit 5 and on the other hand to the space 15 above the piston 12.

When the temperature in the room 1 rises, the throttle valve in the thermostat 4 opens and the controlling output pressure rises. This results on the one hand in a reduction of the temperature of the inlet air in the mixing unit 5 and on the other hand in an increase in the angle of inclination of the vanes 9 in relation to the horizontal, i.e. in an increase in the angle .alpha.. If it is assumed that the flow path a (FIG. 1) originally existed and that this was altered to the curve b as a result of a drop in the temperature of the inlet air, then this alteration is compensated wholly or partially by the change in the vane inlet angle, since if the air is blown in in a steeper upward direction, it takes a path indicated, in a greatly exaggerated way, by the line c in FIG. 1. This means that the stream of air strikes the opposite wall at a point similar to that of air flowing along the line a, i.e. so that troublesome draught is excluded from the desired zone of dwell.

For the sake of completeness it should be stated that the angle of inclination .alpha. is reckoned as being positive above the horizontal and negative below the horizontal, and that it is quite possible for cases to arise in which the vanes have such negative inclination.

There is in general no linear relationship between the change in temperature of the inlet air and the change in the inclination of the vanes. However, if a spring 13 having a non-linear characteristic curve is used, it is possible to effect a setting giving approximately any required operating relationship. For example, use can be made of helical springs wound to conical form, springs arranged in parallel and becoming effective one after the other, a pack of several different plate springs, and etc.

The same considerations apply, if, instead of the mixing unit 5, use is made of means for changing the volume of inlet air per unit time, since as the volume decreases the inlet velocity is reduced. A reduction in velocity also leads to displacement of the flow path from the line a to the line b in FIG. 1. In this case the adjusting device must be so designed that the inclination of the vanes increases as the volume per unit time diminishes, in order to achieve the required compensation.

It is also possible to sense a quantity dependent on a parameter of the inlet air, e.g. the pressure in the direction of flow present in front of the inlet opening, and to vary the inclination of the vanes in dependence thereon.

Claims

I claim:

1. An air conditioning system comprising an enclosed room having wall means with an air inlet opening therein and duct means on the upstream side of said air inlet opening, thermal means in said duct means for raising and lowering the temperature of air flowing through said opening, movable vane means for controlling the angular direction of air flow through said opening, thermostatic means in said room, first operating means responsive to said thermostatic means for modulatingly varying the inclination of said vane means downwardly as the temperature of said room decreases, and second operating means responsive to said thermostatic means for actuating said thermal means to selectively raise and lower the tmeperature of air flowing in said duct means.

2. An air conditioning system according to claim 1 wherein said first operating means includes an expansible chamber device and spring means, said device being biased in one direction by pressurized fluid and in the opposite direction by said spring means, said thermostatic means including a chamber of fluid having fluid communication with said expansible chamber.

3. An air conditioning system according to claim 1 wherein said thermal means is a mixing unit for mixing two streams of air having different temperatures.