A method for controlling a ventilating apparatus

Abstract: A method for controlling a ventilating apparatus (11) for ventilation and temperature control of accommodations, e.g. in vessels. The apparatus is connected to at least one ventilation channel (10) and comprises means for volume control of the air flow to the accommodation, means for temperature control of the air flow to the accommodation, and a control unit (13) for controlling the flow and temperature, for adaption to a desired temperature level. The control unit (13) is manipulated for reduction of temperature from a value of origin to a desired value which is at a certain distance from said value of origin. The flow controlling means and the temperature controlling means are adjusted for a rapid reduction of the temperature during a predestinated period of time. After this period of time has lapsed, these means are reset to provide a temperature level which is lower than the original value which existed before the reduction in temperature was started.

Description: TECHNICAL FIELD The present invention relates to a method for controlling a ventilating apparatus for ventilation and temperature control of accommodations, e.g. in vessels, which apparatus is connected to at least one ventilation channel and comprises means for volume control of the air flow to the accommodation, means for temperature control of the air flow to the accommodation, and a control unit for controlling the flow and temperature, for adaption to a desired temperature level, wherein the control unit is manipulated for reduction of temperature from a value of origin to a desired value which is at a certain distance from said value of origin. BACKGROUND OF THE INVENTION On board vessels, air is supplied to accommodation areas like for example cabins. The air is used for controlling the temperature in the accommodation area and for replacing air which is ventilated out from the area. Each accommodation area which is ventilated in this way, is normally provided with a thermostat, in order to be able to receive values to some sort of regulating or climate control system. A damper means is adjusted automatically in the ventilation apparatus on the basis of a desired value, for example in order to increase the amount of cold air. In cruising ships it is common that the amount of cold air is dimensioned for subsystems and components included in the ventilation system. In this respect, coincident factors are utilized, for avoiding oversizing the systems. One problem which often occurs in this relation, is that the passenger when she/he returns from a short or long visit ashore, has prepared for the return to the cabin by previously adjusting the thermostat to the lowest possible temperature. In this way, the cabin will be cool and nice, e.g. after a hot day on the beech. However, the cabin is often too cool in this adjustment position. Such a control will lead to energy waste during the time when the cabin is not occupied, and will lead to that the cooling apparatus aboard will be more loaded than normally. Another problem is that cleaners who are trying stay cool while they are cleaning the cabin also set the thermostat to the lowest possible temperature and then often forget to reset thermostat afterwards. Several different systems for supply of air and ventilation are known. Usually, 100% fresh air which has been dried and tempered, is supplied to a large number of ventilation apparatuses which at the same time act as diffusors for distributing the air. The supplied air may be heated from a low temperature or be mixed with hot air, so that the temperature in the area will become the desired. Such ventilation apparatuses are adjusted to give the right flow and temperature at the inlet side of the apparatus at the prevailing pressure which in its turn is dependant upon how other ventilation apparatuses in the same ventilation system are adjusted. The adjustment is therefore an iterative process which must be adjusted many times, in order to achieve the desired result. Thus, a malfunctioning ventilation apparatus will affect all other apparatuses within the same system and give rise to inconveniences or repetitive adjustments. Increasing demands for cooling at ships cabins imply that one now has approached the limit for the supplied amount of air which is possible to be supplied to a cabin by a single apparatus, without creating a draft. An increase in the number of ventilation apparatuses would be an uneconomical solution. Through the US 4,553, 696 is known an air conditioning apparatus for ventilation and temperature control of accommodations which is connected to a ventilation channel and comprises means for volume control of the air flow to an accommodation, means for temperature control of the air flow to the accommodation, and a control unit for controlling the flow and temperature, for adaption to a desired temperature level. The apparatus comprises an air flow rate sensor and throttle valve which controls the opening of a duct in accordance with the detection signals from the air flow rate sensor. This known apparatus has certain constructive similarities with the apparatus which is used in the method of the invention, but it solves a different problem. THE TECHNICAL PROBLEM One object of the present invention is to provide a ventilation apparatus with compact installation dimensions, which result in a low intrinsic pressure drop for efficient air supply, with accurate damping over a large flow range, and with a small generation of noise over the entire said flow range. THE SOLUTION This is achieved according to the invention, by adjusting the flow controlling means and the temperature controlling means for a rapid reduction of the temperature in the area, whereby the area is supplied with the maximum available amount of cool air for a pre-programmed period of time and that, these means, after this period of time has lapsed, are reset to provide a temperature level which is lower than the original value which existed before the rapid reduction of temperature was started. By means of a regularly recurring calibration while providing a zero flow, pressure gauges of simple construction can be used. By supplying the control unit with information about characteristics for the means for volume flow control with regard to position - supply pressure - received volume flow, alterations in position can be performed more rapidly and more precisely. DESCRIPTION OF THE DRAWINGS The invention will be described here below with reference to an embodiment shown in the accompanying drawings, in which Fig. 1 shows schematically in a perspective view a ventilation system with a ventilation apparatus for temperature control according to the invention, and Fig. 2 shows in a larger scale a control unit for controlling the ventilation apparatus. DESCRIPTION OF EMBODIMENTS The embodiment of the ventilation system shown in Fig. 1 comprises a ventilation channel 10, a ventilation apparatus 11, a diffusor 12 and a control unit 13. The ventilation channel 10 supplies dried and cool tempered fresh air, which is controlled with regard to flow and temperature in the ventilation apparatus 11. For this object, the ventilation apparatus is provided with not shown means for volume control of the air flow to the diffusor 12 and means for heating the ventilation air. Alternatively, hot and cold air may be supplied to the diffusor via a two channel system, wherein mixing and flow control of the air can be performed in a combined ventilation apparatus/diffusor. The control unit 13 conventionally provided with a not shown temperature sensor for sensing the temperature in the area which the control unit is mounted within. Ventilation openings 14 in the cover which encloses the temperature sensor ensures that the sensor is in contact with the surrounding temperature. The control unit 13 is on its front side provided with a control panel which comprises three control buttons 15, 16 and 17. Of these buttons, the button 15 is used for increasing temperature, the button 16 is used for reduction, and the button 17 is used for producing a rapid reduction of temperature in the area. A series of light emitting diodes 18 are used for indication of temperature alterations from a normal value. When the button 17 is pressed, the area will rapidly be supplied with the maximum available amount of cool air for a pre-programmed period of time, e.g. 10 minutes. A microcomputer within the control unit 13 then requests that the temperature of the area will be allowed to rise to the temperature which prevailed in the area before pressing the button, minus for example 1 °C. This manner of controlling is based upon the assumption, that it could be presumed that the person which pressed the button 17 believed that it was too hot in the cabin, and therefore did not want a return to the temperature which prevailed before said pressing of the button. Also it is sufficient, e.g. for cleaners, if a period of about 10 minutes of maximum coolness is furnished, to manage to get the cleaning done in the cabin, before the system returns to condition "normal". When pressing the button 17, a step motor controlled damper can be made to open, e.g. two times faster than in normal controlling, in order to expedite cooling of the cabin, without premature wear out of, or need for oversizing the step motor and the damper mechanism for this reason. In Fig. 1 is shown the connection of a computer 19 to the control 13. The computer is used for adjusting in the ventilation apparatus, with regard to the flow control range of the damper means. In order to be able to use pressure gauges of a more simple and less expensive quality, i.e. gauges for which characteristics related to the outsignal as a function of applied pressure is changing in course of time, an automatic calibration is used with a periodicity which provides an acceptable degree of accuracy for the pressure gauge between calibrations. These are performed by providing a zero flow through the ventilation system, wherein the outsignal is measured. The value is stored in a memory and is used for adjusting the outsignal. The zero flow is accomplished by stopping the fan which serves the system by a time function. The calibration is performed zero flow is obtained during a certain period of time. The detection that a zero flow is obtained will be assumed to exist whenever the outsignal from the pressure gauge falls below a certain level. Because variations in supplied pressure in the channel system may be caused by variations in air consumption from the other connected apparatuses, By variation in wind pressure at inlets/outlets of the fans which serve the system, etcetera, the flow at unchanged position of volume controlling means will be changed. The prior art process to maintain a certain flow and to alter the flow is normally performed by a feedback coupling of the value of the supplied flow, to the control unit. This prior art feedback coupling may produce inertia and problems in the entire control system during the transient period, which in its turn will lead to temperature variations in the area and to an unnecessary high consumption of energy and wear on means for control of volume flow. This is avoided by also supplying the control unit 13 with information about characteristics for the means for volume flow control with regard to position - supply pressure - received volume flow, so that alterations in position can be performed more rapidly and more precisely. The invention is not limited to the above described embodiment, but several variations are conceivable within the scope of the accompanying claims.

Claims: A method for controlling a ventilating apparatus (11) for ventilation and temperature control of accommodations, e.g. in vessels, which apparatus is connected to at least one ventilation channel (10) and comprises means for volume control of the air flow to the accommodation, means for temperature control of the air flow to the accommodation, and a control unit (13) for controlling the flow and temperature, for adaption to a desired temperature level, wherein the control unit (13) is manipulated for reduction of temperature from a value of origin to a desired value which is at a certain distance from said value of origin, characterized in that the method comprises a rapid reduction of temperature function (17) with the following steps: the flow controlling means and the temperature controlling means are adjusted for a rapid reduction of the temperature in the area, whereby the area is supplied with the maximum available amount of cool air for a pre-programmed period of time, and that, these means, after this period of time has lapsed, are reset to provide a temperature level which is lower than the original value which existed before the rapid reduction of temperature was started. A method according to claim 1, characterized in that a precise flow control is achieved by a regularly recurring zero calibration of a differential pressure gauge included in the control unit (13), which calibration is performed by a detection of a zero flow by said control unit. A method according to claim 1, characterized in that the control unit (13) is supplied with information regarding damping characteristics for the means for volume flow control, which information can be used for rapid and precise temperature control of the accommodation area, and for saving energy.

Inventors: AHLFORS THOMAS, BERGSTROEM GARY, GOETMALM OERJAN, AHLFORS, THOMAS, BERGSTROEM, GARY, GOETMALM, OERJAN, BERGSTRÖM, Gary, GÖTMALM, Örjan
Applicants: FLAEKT AB, ABB FLAEKT AB
Application year: 1995
Main classification: F24F11
IPC codes: F24F11, B63J2