FR3101022A1 - Method of regulating the temperature within the passenger compartment of a motor vehicle - Google Patents

Abstract

The invention relates to a method of regulating the temperature within a passenger compartment (10) of a motor vehicle (1) equipped with an air conditioning system (2), or of a zone of this passenger compartment (10). , the method comprising the step of measuring (40) the level of perspiration of a skin area (30) of an occupant (3) of the vehicle by measuring the amount of water present in the skin area (30) , by means of a sensor (28) arranged in the passenger compartment (10) for capturing images of said skin zone (30) in the near infrared range, the skin zone (30) being located at the level of the head of the patient. the occupant (3). Figure for the abstract: Fig. 1

Description

Process for regulating the temperature within the passenger compartment of a motor vehicle

The invention relates to the field of motor vehicle air conditioning and heating systems.

Air conditioning is a comfort element that is increasingly being installed in motor vehicles. When the air conditioning/heating system has to lower the temperature of the passenger compartment, the air is cooled using the cooling energy produced by a conventional air conditioning circuit, implementing a cycle of compression/expansion of a refrigerant. When the air conditioning/heating system has to raise the temperature of the passenger compartment, the air is heated using the thermal energy generated by the vehicle's engine, this air being heated by passing through a heater connected to the cooling circuit of the engine. In both cases, the air (cooled or heated) is sent to the passenger compartment by means of a ventilation system.

As the air conditioning system is an important element of comfort for users, car manufacturers are very attentive to the perceived quality of air conditioning and ventilation systems.

The aim of the invention is to improve the perceived quality and the comfort felt by users.

To this end, the invention relates to a method for regulating the temperature within a passenger compartment of a motor vehicle equipped with an air conditioning system, or of a zone of this passenger compartment, the method comprising the step of measuring the level of sweating of a skin area of a vehicle occupant by measuring the amount of water present at the level of the skin area, by means of a sensor arranged in the passenger compartment to capture images of said area in the near infrared range, the skin area being located at the level of the occupant's head.

Thus, by measuring the level of sweating of a skin zone located at the level of the head of an occupant of the vehicle, the method in accordance with the invention makes it possible to have valuable information concerning the state of comfort of the occupant, and thus makes it possible to modulate the operation of the air conditioning system according to this information. Indeed, a high level of sweating will indicate that the occupant is in a state of discomfort, and appropriate corrective actions can be taken, such as increasing the flow of air blown into the passenger compartment and/ or lower the set temperature of the air conditioning system. In addition, by measuring the level of sweating at the level of the head of the occupant, and in particular at the level of the forehead, we measure the sweating on one of the most reactive areas of the body in terms of sweating. The method according to the invention therefore makes it possible to quickly and finely detect the evolution of the occupant's sweating, and thus to carry out effective monitoring of this parameter.

In one embodiment, the skin area is located at the forehead of the occupant.

In one embodiment, the method comprises the step of comparing the level of sweating of the skin area with a threshold value, the method comprising the step of modulating the flow rate of the air blown into the passenger compartment by the air conditioning system and/ or a setpoint temperature of the air conditioning system if the level of sweating of the skin zone is greater than or equal to the threshold value.

In one embodiment, the threshold value is predetermined, for example being stored beforehand in a memory on board the motor vehicle, or is determined for an occupant on the basis of a history of measurements carried out on this same occupant.

In one embodiment, the quantity of water measured at the level of the skin area of the occupant is compared with a reference level, the reference level being for example measured at the level of the surface of an eye of the occupant and /or at the skin area of the occupant.

In one embodiment, the sensor is a near infrared camera.

In one embodiment, the near infrared camera captures image data in the spectrum of light with a wavelength between 700 nanometers and 5000 nanometers, preferably between 700 nanometers and 2000 nanometers.

The invention also relates to an air conditioning system comprising a refrigeration circuit and a distribution circuit arranged to implement a method in accordance with that defined above.

The invention also relates to a motor vehicle implementing a method in accordance with that defined above and/or comprising an air conditioning system in accordance with that defined above.

The present invention will be better understood on reading the following detailed description, made with reference to the accompanying drawings, in which:

FIG. 1 represents the passenger compartment of a motor vehicle comprising an air conditioning system configured to implement a method in accordance with the invention.

FIG. 2 is a flowchart representing the steps of an exemplary method according to the invention.

FIG. 1 represents the passenger compartment 10 of a motor vehicle 1, the vehicle 1 being equipped with an air conditioning system 2 making it possible to lower or raise the temperature within the passenger compartment 10 (or within one or more zones of this passenger compartment, in a differentiated manner), and to keep it constant and equal to a set temperature given by the user or users.

The air conditioning system 2 comprises a refrigeration circuit 20, a heating circuit 22 and a distribution circuit 24. The refrigeration circuit 20 ensures the production of cold air when the air conditioning system is in air conditioning mode, and implements to this effect a compression/expansion cycle of a refrigerant. The heating circuit 22 ensures the production of hot air when the air conditioning/heating system is in heating mode, and for this purpose implements the recovery of part of the thermal energy produced by the engine of the vehicle, by example via a heater connected to the engine cooling circuit.

In each of these two modes (air conditioning and heating), the cold air or the hot air thus produced is supplied to the distribution circuit 24 which ensures the blowing of this air into the passenger compartment 10 of the vehicle.

The distribution circuit 24 comprises at least one air blower (not shown), connected by pipes to a plurality of ventilation nozzles 26, making it possible to blow the cooled air (or, if necessary, heated) into the cabin 10 of the vehicle 1, to lower (or, where appropriate, raise) the temperature.

The air conditioning system 2 is thus configured to regulate the temperature in the passenger compartment 10 (or, if it is a so-called "multi-zone" system, the temperature at the level of delimited zones of the passenger compartment). Thus, when the user activates the air conditioning/heating system by adjusting a set temperature, the air conditioning/heating system produces and blows cold or hot air depending on whether it is necessary to lower or raise the temperature. temperature of the passenger compartment 10 to reach and maintain this setpoint temperature.

In accordance with the invention, the air conditioning system 2 comprises a sensor 28 arranged to measure the level of sweating of one or more occupants of the vehicle, such as the driver 3 shown in Figure 1. In the example of Figure 1, sensor 28 is a PIR camera (PIR stands for "Near IR", or near infrared). PIR cameras (also referred to as "NIR Camera" for "Near Infrared Camera") are cameras that capture image data in the near infrared spectrum. Near infrared radiation has a wavelength between about 700 nanometers and about 2000 nanometers. The sensor 28 is arranged for example at the level of the dashboard or on the ceiling of the vehicle, close to the upper edge of the windshield.

By capturing images of a vehicle occupant with a PIR camera, and more specifically by capturing images of a portion of visible skin, it is possible to determine the level of sweating of this occupant. Indeed, the formation and elimination of sweat on the skin can be detected and measured thanks to the ability of water molecules to absorb electromagnetic radiation in the near infrared spectrum. Indeed, the quantity of light absorbed is linked to the quantity of water present on the surface of the skin. Thus, by measuring the absorption of light in the near infrared spectrum at the level of a portion of the skin of an occupant, we are able to follow the evolution of the level of sweating of this occupant, which gives a return useful information for evaluating and optimizing the efficiency of the air conditioning system, and for controlling it.

In accordance with the invention, the zone of the skin which is monitored by means of the sensor 28 is the head of the occupant, and more precisely the zone of the forehead 30 of the latter. The forehead area is indeed a very reactive area as far as sweating activity is concerned, it is therefore very interesting to monitor this particular area in the context of the invention.

Advantageously, the quantity of water detected at the level of the cutaneous zone can be compared with a reference level. Advantageously, this reference level can be measured at the level of one eye, given that the tear film covering each eye is substantially constant. The absorption of light in the near infrared range at eye level will therefore be substantially constant, making it an interesting point of reference. Alternatively or in addition to the surface of the eye, it is possible to measure a reference level at the level of the skin zone 30, preferably if the temperature (of the ambient air and/or of the skin) is lower than a limit value, this limit value being for example less than or equal to 20°C. Indeed, below such a temperature, the quantity of water present on the skin will be nil or very low, which makes it possible to measure a reference value making it possible to follow the evolution of the quantity of water on the surface. skin.

Figure 2 shows the steps of a method according to the invention, which comprises in the example:

• step 40 of measuring the level of sweating of the skin area 30 of the occupant 3;
• step 42 comparing the measured sweat level to a threshold value;
• step 44 to modulate the flow of the blown air and/or the setpoint temperature of the air conditioning system 2.

Advantageously, the method in accordance with the invention makes it possible to compare the level of sweating measured at the level of the cutaneous zone with a threshold value, this threshold value being for example representative of a limit of discomfort. In this example, if the level of sweating measured at the occupant exceeds the threshold value, then it will be determined that this occupant has an uncomfortable level of sweating and an action will be taken, such as for example increasing the ventilation power to increase the flow. of air blown into the passenger compartment 10 and/or lowering the set point temperature of the air conditioning system. Advantageously, the threshold value may depend on the occupant, and constitute data stored on board a memory of the vehicle, this value being "learned" by a computer managing the air conditioning system, that is to say determined on the basis of a plurality of measurements for an identified occupant.

Claims (9)

Method for regulating the temperature within a passenger compartment (10) of a motor vehicle (1) equipped with an air conditioning system (2), or of a zone of this passenger compartment (10), the method comprising step of measuring (40) the level of sweating of a skin area (30) of an occupant (3) of the vehicle by measuring the quantity of water present at the level of the skin area (30), by means of a sensor (28) arranged in the passenger compartment (10) to capture images of said skin area (30) in the near infrared range, the skin area (30) being located at the level of the head of the occupant (3 ). Method for regulating the temperature according to the preceding claim, in which the skin area (30) is located at the level of the forehead of the occupant (3). Regulation method according to one of the preceding claims, comprising the step of comparing (42) the level of sweating of the cutaneous zone (30) with a threshold value, the method comprising the step of modulating (44) the flow rate of the air blown into the passenger compartment by the air conditioning system (2) and/or a setpoint temperature of the air conditioning system (2) if the level of sweating of the skin area (30) is greater than or equal to the threshold value . Regulation method according to the preceding claim, in which the threshold value is predetermined, being for example previously stored in a memory on board the motor vehicle (1), or is determined for an occupant (3) on the basis of a history of measurements taken on the same occupant (3). Regulation method according to one of the preceding claims, in which the quantity of water measured at the level of the skin zone (30) of the occupant (3) is compared with a reference level, the reference level being for example measured at the surface of an eye of the occupant (3) and/or at the skin area (30) of the occupant (3). Regulation method according to one of the preceding claims, in which the sensor (28) is a near infrared camera. Method according to the preceding claim, in which the near infrared camera captures image data in the spectrum of light with a wavelength between 700 nanometers and 5000 nanometers, preferably between 700 nanometers and 2000 nanometers. Air conditioning system (2) comprising a refrigeration circuit (20) and a distribution circuit (24) arranged to implement a method according to one of the preceding claims. Motor vehicle (1) comprising an air conditioning system according to the preceding claim.