WO2010136141A2

WO2010136141A2 - Thermostat with at least one sensor of ambient light

Info

Publication number: WO2010136141A2
Application number: PCT/EP2010/003047
Authority: WO
Inventors: Pierdavide Pezzutto; Adriano Montagner
Original assignee: Esseci Srl
Priority date: 2009-05-27
Filing date: 2010-05-19
Publication date: 2010-12-02
Also published as: IT1395669B1; ITTV20090111A1; WO2010136141A4; WO2010136141A3

Abstract

The present invention relates to occupancy controllers based on variation in ambient light. Every time a body passes between the source of light and the light sensor, it determines a variation in luminosity which is used to adjust the amount of energy necessary to heat/cool the room itself. The time sequence of the variations and their duration allow the adjustment of the comfort temperature in a way which is natural and very similar to the human habits. During night time there will be a reduced and energy-conserving comfort temperature; during daytime such value will depend on the duration and intensity of the activity undertaken in the room.

Description

DESCRIPTION OF THE INVENTION

Title: "Thermostat with at least one sensor of ambient light"

BACKGROUND OF THE INVENTION

Residential thermal management plays an important role in energy expenditure. Actions to achieve energy savings result in: 1. lower use of energy and lower costs of heating/cooling; 2. better living conditions in residential/commercial living area and greater comfort for its inhabitants; 3. protection of the environment and reduction of planetary pollution. The state of art is represented by the prototype of a "Smart Home" based on a central energy control system, which is rather complex from a technical point of view. By using specific remote controls, the system continuously monitors consumptions and environmental parameters (such as flooding and gas leaks), manages the ignition priority of household appliances, autonomously manages the adjustments (i.e. temperature) and reports any alarm events to the user or to the support services. From economical and user's point of view it is not accessible to everybody. It has long been recognized that a family can achieve considerable energy savings by simple solutions which contribute to avoiding the costs arising from energy wastes, due to omissions and oversights. An early energy saving technique required an occupant of the controlled area to set working programs or to manually set a reduced temperature set-point, lower than the usual comfort level, during the night or during the unoccupied periods. Exceptions to the set programs may often occur: the occupant leaves the house or opens the windows to air or clean a room while heaters/coolers are on, or he is working in a room (i.e. kitchen) while heating is on in another unoccupied room too (i.e. bedroom). In order to optimize the heating/cooling management and make it automatic, the

i use of a passive infrared (PIR) sensor, so-called "occupancy sensor", has been introduced to be externally connected to the thermostat. Thus, the thermal energy will be supplied according to the motion and consequently to the room occupancy (see US 4,407,447). On the one hand it allows to avoid useless energy consumptions whenever a room is unoccupied, but on the other hand it may cause useless start-ups, due to uncontrollable events, such as domestic animals in the house. Therefore, motion as unique condition is insufficient and not always valid to make an intelligent and logic control of heating/cooling. In order to optimize the heating/cooling management and make it automatic, the use of light / solar radiation sensitive devices has been introduced: they allow the thermostat to automatically shift from the day setting to the night one, and automatically reduce the temperature set-point (see GB 1,005,175). On the one hand it allows a reduction of energy wastes by ensuring a lower energy consumption during night time, but on the other hand it does not guarantee the real need of heating during the day. Therefore, light as unique condition is insufficient and not always valid to make an intelligent and logic control of the heating/cooling. More complex and sophisticated solutions have been developed in attempts to integrate the control activity of a thermostat with the data provided by light detectors, motion detectors, sound detectors, etc. (see US 2002/134849 Al, US 6 066 843 A, US 5 088 645 A). They of course contribute to optimize the energy consumption but at an increased cost and complexity.

Thus there is the need in the art for a simple and efficient thermostat which is easy to install on an existing plant and able to adjust gradually the thermal energy supply to the real occupancy of the controlled area. This thermostat should detect the transition from a light condition to a temporary shadow condition, which can be considered a confirmation of the performing of human activity in a room. DESCRIPTION OF DRAWINGS:

The invention declared in this patent application is represented by DRAWING 1, DRAWING 2 and DRAWING 3, where: DRAWING 1 : ELECTRIC CIRCUIT

(30) Sensor of ambient light;

(31 ) Electric circuit "amplifier / impedance matcher";

(33) Electric circuit which generates an electric pulse (34) to every variation (32);

(35) Electric circuit "threshold detector" (36).

DRAWING 2: BLOCK DIAGRAM

(10) Electric circuit of the luminosity detector;

(12) Thermal detector -ambient temperature;

(14) Logical unit -microprocessor;

(16) Heating / Cooling control relay.

DRAWING 3: DIAPHRAGM OR LIGHT APERTURE STOP

(20) Natural and/ or artificial luminous source;

(22) Diaphragm or luminous intensity aperture stop;

(24) Light screen;

(26) Sensor of ambient light.

STATEMENT t_dark Minimum delay necessary to detect the absence of light. tjight Minimum delay necessary to detect the presence of light. t saving Delay on reduction of thermal comfort level {set-point light). set-point dark Thermostat set-point in a condition of dark. set-point light Thermostat set-point in a condition of light. delta_saving Thermal value to be subtracted from the set-point value during a condition of light. unit saving Thermal saving unitary value. max_saving Maximal value attributable to delta saving.

THERMOSTAT WINTER MODE

Detection of a protracted darkness condition: When the signal (36) remains equal to (- VDD) for a time t_dark, a darkness condition is detected and the variation in thermal saving deltajsaving which might have been stored over the time, is cancelled. The logical unit (14) keeps the electrical unit (16) activated, only if the temperature read by the thermal sensor (12) is lower than the set-point _dark.

Detection of a protracted light condition: Once the darkness condition has been detected, the signal (36) has to remain equal to (+VDD) for a time tjight to go back to the condition of light. The logical unit (14) keeps the electrical unit (16) activated, only if the temperature read by the thermal sensor (12) is lower than set-point Jight minus delta saving. Motion detection: Motion detection is activated only after signal (36) has remained equal to (+VDD) for a time tjight. Every time the signal (34) switches from (-VDD) to (+VDD), the logical unit (14) resets the timer t_saving and cancels the value of the accrued thermal saving, deltajsaving. The logical unit (14) keeps the electrical unit (16) activated, only if the temperature read by the thermal sensor (12) is lower than set-point Jight minus deltajsaving. Absence of motion: If the signal (34) remains equal to (-VDD) until conclusion of time tjsaving, the timer will be reset and the value deltajsaving will be increased by unitjsaving until it reaches the max saving. The logical unit (14) keeps the electrical unit (16) activated, only if the temperature read by the thermal sensor (12) is lower than set-point Jight minus deltajsaving. THERMOSTAT SUMMER MODE

Detection of protracted darkness condition: When the signal (36) remains equal to (-VDD) for a time t dark, a darkness condition is detected and the variation in thermal saving deltajsaving which might have been stored over the time, is cancelled. The logical unit (14) keeps the electrical unit (16) activated, only if the temperature read by the thermal sensor (12) is higher than the set-point _dark.

Detection of protracted light condition: Once the dark condition has been detected, the signal (36) has to equal (+VDD) for a time equivalent to t light in order to go back to the condition of light. The logical unit (14) keeps the electrical unit (16) activated, only if the temperature read by the thermal sensor (12) is higher than set-point light plus delta jsaving. Motion detection: Motion detection is activated only after signal (36) has remained equal to (+VDD) for a time t Jight. Every time the signal (34) switches from (-VDD) to (+VDD), the logical unit (14) resets the timer t saving and cancels the value of the accrued thermal saving, delta saving. The logical unit (14) keeps the electrical unit (16) activated, only if the temperature read by the thermal sensor (12) is higher than set-point Jight plus delta saving. Absence of motion: If the signal (34) remains equal to (-VDD) until conclusion of time t jsaving, the timer will be reset and the value delta saving will be increased by unitjsaving until it reaches the max_saving. The logical unit (14) keeps the electrical unit (16) activated, only if the temperature read by the thermal sensor (12) is higher than set-point Jight plus deltajsaving.

EXAMPLE:

It is hereby described a use of the thermostat with at least one sensor of ambient light, as an illustrative, yet not exclusive example: The thermostat with at least one sensor of ambient light, has to be mounted on the wall opposite to the heat exchanger, as any other thermostat. Once it has been mounted, this thermostat does not need any specific setting; in many cases it is not even necessary to set the working periods since its sensor is able to detect whether the controlled area is occupied or not. The thermostat with at least one sensor of ambient light detects the dark/light condition and considers an instant variation in light as possible motion. Thus it learns that a human activity is in progress in the controlled area and adjusts automatically the thermal supply. The occupancy is free from any strict setting, which previously forced the occupant to manually switch off the thermostat or set it to a lower temperature before leaving the area for an unforeseen event. Indeed if no variation in light is detected in a room for a period of time previously set by the user, the thermostat with one or more sensors of ambient light "understands/learns" that the room is unoccupied and automatically reduces the comfort temperature. On the occupant return, the thermostat with at least one sensor of ambient light detects a variations in light, which means occupancy, and automatically adjusts the energy supply in order to efficiently reach again the usual comfort temperature. That happens either if the occupant on his return turns on the artificial light, causing an immediate variation in light, either if the room is already lit (naturally or artificially) since the thermostat detects the state of shadow as the occupant passes in the operating area of the device.

The variation in light is analysed according to the variable "time" in order to avoid false startups, which may be caused by natural events, such as sunrise, sunset, a tree shadow, storm, etc.

Claims

CLAIMSWhat is claimed is:

1. A thermostat with at least one sensor of ambient light with spectrum between 400- 800nm, characterised by: a. a sensor of ambient light (26) mounted within a light screen (24) having at least one diaphragm or one light aperture stop (22) in order to increase the variation in tension due to the changes in light as would occur if a person or an object passes between the light source (20), which may be direct and/or diffused, artificial and/or natural, and the sensor of ambient light (26); b. an automatic system to adjust the thermal set-point.

2. A thermostat as claimed in claim 1, characterised by the fact that the set sensor (26) and/or screen (24) and/or diaphragm (22) may be developed by combining/unifying one or more of the said components together.

3. A thermostat as claimed in claim 1, characterised by the fact that it employs the variation in tension provided by the sensors of ambient light (26) to obtain electric thresholds and/or pulses, which signal the condition of light and/or dark and/or motion, in order to adjust the thermal set-point.

4. A thermostat as claimed in claim 1, characterised by the fact that said sensor of ambient light (30) may be polarized to (+VDD) or -(VDD) with or without amplifier / impedance matcher (31).

5. A thermostat as claimed in claim 4, characterised by the fact that the variation in tension provided by the sensors of ambient light may be processed by a microprocessor logic unit with or without the use of the electric circuit (33) with or without the use of the electric circuit (35). A thermostat as claimed in claim 1, characterised by having one sensor of ambient light (10) external to the thermostat itself and in communication with the latter through a proper type of connection, such as bus on electric wires or radiofrequency or other "wireless" type.