EP2146154B1 - Device for controlling a fixed-capacity compressor - Google Patents

Description

Technical Field of the Invention

The present invention is in the field of ventilation, heating and / or air conditioning of a motor vehicle. It relates to a device for controlling the start of a fixed capacity compressor. It also relates to an air conditioning loop comprising such a compressor. Finally, it relates to a ventilation installation, heating and / or air conditioning comprising such a loop and a method of implementation of said device.

State of the art

A motor vehicle is commonly equipped with a ventilation, heating and / or air conditioning system to modify the aerothermal parameters of the air contained inside the passenger compartment of the vehicle. Such an installation comprises an air conditioning loop inside which circulates a cooling fluid, such as a subcritical fluid, R134a in particular or the like, or such as a supercritical fluid, especially R744 or the like. The air conditioning loop comprises at least one compressor, a condenser or a gas cooler, an expansion member and an evaporator. The air conditioning loop also optionally includes an internal heat exchanger. A flow of air passes through the evaporator to be cooled prior to delivery to the interior of the passenger compartment (see for example the document EP-1544556-A ).

The compressor is a fixed capacity compressor for which the swept volume is constant. Control means control the start of the compressor from a measurement of the temperature of the air flow at the outlet of the evaporator and a comparison of said measured temperature with two set temperatures. More particularly, the compressor is put in operates when the temperature of the air flow measured at the outlet of the evaporator is greater than a first setpoint temperature and the starting of the compressor is stopped when the temperature of the air flow measured at the outlet of the evaporator is lower than at a second setpoint temperature, the latter being lower than the first setpoint temperature.

A general problem posed by such an installation lies in the fact that the start-up of the compressor, and conversely the shutdown of the latter, are conditioned by said setpoint temperatures which are fixed and independent of any variations in the conditions of the compressor. use of said loop. However, in certain circumstances, it may be desirable to make more flexible the modalities for starting and / or stopping the compressor, in particular with a view to rapidly improving the thermal comfort desired by the user of the vehicle, and or to save energy from using the compressor only if it is needed.

Object of the invention

The object of the present invention is to provide a device for controlling the start-up of a fixed capacity compressor which is simple and inexpensive to produce, robust, compact, easily integrable inside a ventilation system. , heating and / or air conditioning of a motor vehicle, such a device to achieve a saving of energy necessary for the implementation of the compressor. Another object of the present invention is to provide an air conditioning loop equipped with such a device, said loop providing a thermal comfort quickly optimized compared to a thermal state of the air contained inside the cabin. Another object of the present invention is to propose a ventilation, heating and / or air-conditioning system for a vehicle which comprises such a loop and which is simple and inexpensive to implement, said installation being little consumer of energy. A last goal of the present invention is to provide a method of using such an air conditioning loop that is easy to implement.

The control device of the present invention is a device for controlling a fixed capacity compressor associated with an evaporator traversed by an air flow in a direction of flow of the air flow. Said compressor and said evaporator constitute an air conditioning loop of a ventilation, heating and / or air conditioning of a motor vehicle. Said device comprises a sensor for measuring a measured value VM of a characteristic C of a fluid FR, A and means for comparing the measured value VM of the characteristic C of the fluid FR, A with at least two threshold values VSmin, VSmax of said characteristic C.

According to the present invention, said device comprises an upstream temperature sensor intended to be arranged upstream of said evaporator in said direction of flow to measure an upstream temperature T2 of the air flow and to deliver information which is taken into account by said device to determine the threshold values VSmin, VSmax of said characteristic C.

These provisions are such that the threshold values VSmin, VSmax are determined from information relating to the upstream temperature T2 of said air flow measured upstream of the evaporator and are likely to vary according to said information. It follows that the threshold values VSmin, VSmax are determined according to the nature of a thermal load affecting the evaporator.

Said device is advantageously an autonomous device equipped with connection means to a power source for the implementation of the sensor of said measured value VM and the upstream temperature sensor.

These arrangements are such that said device is independent of any other control device which gives it the advantage of being able to be installed in a relatively arbitrary location of said installation. More particularly, the device can be housed inside an elementary housing which is easily reportable on a housing constituting said installation and inside which housing circulates the air flow.

The comparison means are preferably constituted by an operational amplifier.

The comparison means are preferably associated with means for determining the two threshold values VSmin, VSmax of said characteristic C from the information relating to the upstream temperature T2 of the airflow.

An air conditioning circuit of a ventilation, heating and / or air conditioning system of a motor vehicle according to the present invention is mainly recognizable in that said loop comprises such a control device.

The fluid FR, A is for example constituted by air A forming the air flow, the characteristic C consisting of a downstream temperature T1 of the air flow measured downstream of the evaporator in the direction of flow of the air. air flow therethrough and in that the threshold values VSmin, VSmax consist of respective minimum values T1 min and maximum T1 max of said downstream temperature T1.

The fluid FR, A is for example still constituted by a refrigerant fluid FR flowing inside said loop, the characteristic C being constituted by a pressure P of said refrigerating fluid FR inside the evaporator and in that that the threshold values VSmin, VSmax consist of respective minimum values Pmin and maximum Pmax of said pressure P.

A ventilation, heating and / or air conditioning system of the present invention is mainly recognizable in that said installation comprises such an air conditioning loop.

Said installation comprises in particular an admission flap of the air flow inside a housing constituting the installation.

The upstream temperature sensor is for example disposed downstream of said flap in the direction of flow of the air flow inside said installation.

The upstream temperature sensor is for example still disposed upstream of said flap in the direction of flow of the air flow inside said installation.

An implementation method according to the present invention of such a control device is characterized in that said method comprises a step of determining said threshold values VSmin, VSmax as a function of said information relating to the upstream temperature T2 of the flow. air taken upstream of the evaporator.

• d'une étape de mise en marche du compresseur, si la valeur mesurée VM de la caractéristique C est supérieure à la valeur-seuil maximale Vmax, ou
• d'une étape d'arrêt de la mise en marche du compresseur, si la valeur mesurée VM de la caractéristique C est inférieure à la valeur-seuil minimale Vmin.

Said determination step is advantageously followed:

• a step of starting the compressor, if the measured value VM of the characteristic C is greater than the maximum threshold value Vmax, or
• a step of stopping the start of the compressor, if the measured value VM of the characteristic C is lower than the minimum threshold value Vmin.

Description of the figures.

• La fig.1 est une illustration schématique d'une installation de ventilation, de chauffage et/ou de climatisation comprenant une boucle de climatisation selon la présente invention.
• La fig.2 est une illustration schématique d'une méthode d'utilisation de la boucle de climatisation représentée sur la figure précédente.
• La fig.3 est une illustration schématique du résultat de la mise en oeuvre de la méthode illustrée sur la figure précédente.
• La fig.4 est une illustration schématique d'une variante de réalisation de moyens de commande d'un compresseur participant de la boucle de climatisation représentée sur la fig.1.

The present invention will be better understood, and details will arise from reading the description which will be made of variants in connection with the figures of the attached plates, in which:

• The fig.1 is a schematic illustration of a ventilation, heating and / or air conditioning installation comprising an air conditioning loop according to the present invention.
• The fig.2 is a schematic illustration of a method of using the air conditioning loop shown in the previous figure.
• The fig.3 is a schematic illustration of the result of the implementation of the method illustrated in the previous figure.
• The fig.4 is a schematic illustration of an alternative embodiment of control means of a compressor participating in the air conditioning loop shown on the fig.1 .

On the fig.1 a motor vehicle is equipped with a ventilation, heating and / or air conditioning installation 1 for modifying the aerothermal parameters of the air contained inside the passenger compartment of the vehicle. In general, the installation 1 comprises a housing 2 inside which circulates a flow of air 3 prior to its delivery to the interior of the passenger compartment. More particularly, the housing 2 is equipped with an air inlet 4 through which the air flow 3 is admitted inside the housing 2 and an air outlet 5 through which the air flow 3 is delivered inside the cabin. The air flow 3 flows inside the housing 2 from the air inlet 4 to the air outlet 5 in a flow direction 6 of the air flow 3. The inlet of air 4 is provided with an air intake flap 7. The latter 7 is operable between an open position in which it allows an intake of air inside the casing 2 and a closed position in which he forbids such admission.

To modify the temperature of the air flow 3 prior to its delivery inside the passenger compartment, said installation 1 comprises an air conditioning loop 8 inside which circulates a refrigerant fluid FR, indifferently subcritical or supercritical . The air conditioning loop 8 comprises a compressor 9 for compressing the refrigerant, a condenser 10 or a gas cooler 10 inside which the coolant transfers heat to its environment, an expansion member 11 inside which the refrigerant is subjected to an expansion and an evaporator 12 for cooling said air flow 3 which passes through the latter 12. The air conditioning loop may also include an internal heat exchanger , not shown on the fig.1 , which more particularly describes an air conditioning loop 8 inside which circulates a subcritical refrigerant FR. Inside such an air conditioning loop 8, the refrigerant fluid FR flows from the compressor 9, to the condenser 10, then to the expansion device 11, then to the evaporator 12 to finally return to the compressor 9. However, the present invention also applies to an air conditioning loop 8 inside which circulates a supercritical refrigerant FR.

The compressor 9 is a fixed capacity compressor for which the swept volume is constant. The compressor 9 is equipped with a control device 13 to determine a starting and / or a shutdown of the compressor 9. For this purpose, and referring also to the fig.2 , the control device 13 comprises comparison means 14 between a measured value VM of a characteristic C of a fluid FR, A and two threshold values VSmin, VSmax of the characteristic C of the fluid FR, A. Said threshold values VSmin, VSmax are respectively a minimum threshold value VSmin of the characteristic C of the fluid FR, A and a maximum threshold value VSmax of the characteristic of the fluid FR, A, the latter VSmax being greater than the value. minimum threshold VSmin. The compressor 9 is started when the measured value VM of said characteristic C is greater than said maximum threshold value VSmax. The compressor 9 is stopped when the measured value VM of said characteristic C is less than said minimum threshold value VSmin.

According to a first variant, said fluid FR, A consists of air A forming the air flow 3 which passes through the evaporator 12, said characteristic C consisting of a downstream temperature T1 of the air flow 3 measured in downstream of the evaporator 12 in the direction of flow 6 of the air stream 3 through the evaporator 12, and both Threshold values VSmin, VSmax consist of a minimum downstream temperature T1min and a maximum downstream temperature T1max of the air stream 3. In this case, said downstream temperature T1 is measured via a downstream sensor 15 temperature, such as a negative temperature coefficient resistance, commonly referred to by the acronym "CTN" or such as a thermomechanical control device.

According to a second variant, said fluid FR, A consists of the refrigerant fluid FR which circulates inside the air conditioning loop 8, the said characteristic C consists of a pressure P of the refrigerant fluid FR measured inside the the evaporator 12, and the two threshold values VSmin, VSmax consist of a minimum pressure Pmin and a maximum pressure Pmax of the refrigerant FR. In this case, the pressure P of the refrigerant is measured either by means of a pressure sensor 16, such as a transducer or by means of a pressure switch.

According to the known prior art, the threshold values VSmin, VSmax are fixed and remain constant whatever the conditions of use of the air conditioning loop 8, in particular whatever the nature of a thermal load affecting the evaporator 12.

In order to overcome this disadvantage, especially with a view to saving energy necessary for the implementation of the compressor 9, it is proposed by the present invention that the control means 13 comprise determining means 17 able to vary the values thresholds VSmin, VSmax as a function of information 18 received by the determination means 17.

Said information 18 is information relating to an upstream temperature T2 of the air flow 3 measured upstream of the evaporator 12 in the direction of flow 6 of the air flow 3 through the evaporator 12. Said upstream temperature T2 is measured by an upstream temperature sensor 20, such as a resistance to Negative temperature coefficient "CTN". According to a first embodiment, the upstream temperature sensor 20 is disposed downstream of said air intake flap 7 while according to a second embodiment, the upstream temperature sensor 20 is disposed upstream of said intake flap The latter option has the advantage of offering the possibility of using as an upstream temperature sensor 20 an external temperature sensor which is commonly equipped with the motor vehicle, which generates no additional cost.

According to this first embodiment, for example, the following values of T1max and T1min are proposed as a function of said information 18 relating to the upstream temperature T2 of the air stream 3 measured upstream of the evaporator 12: T2 > 30 ° C 25 ° C 20 ° C 15 ° C <10 ° C T1max 5 ° C 7 ° C 9 ° C 11 ° C 5 ° C T1min 2 ° C 4 ° C 6 ° C 8 ° C 2 ° C

In this example, it is remarkable that the values T1max and T1min satisfy the relation R: $$\mathrm{T}\mathrm{1}\max -\mathrm{T}\mathrm{1}\min =\mathrm{3}\mathrm{°\; C}\left(\mathrm{R}\right)$$

On the fig.3 , is illustrated the result of an implementation of such an air conditioning loop 8 according to the method of the present invention in which different values of T1max and T1min are obtained as a function of the measured value of the upstream temperature T2 of the flow of air 3 measured upstream of the evaporator 12.

On the fig.4 is shown an advantageous embodiment of said control device 13. The designers of the present invention have chosen to provide a simple and inexpensive embodiment of the control device 13. The latter 13 is particularly likely to be housed inside an elementary housing 21 which is adapted to be installed in a relatively arbitrary location of said installation 1. The control device 13 proposed by the The present invention is an autonomous device that is independent of other means of control and / or control that may comprise said installation. It follows a strong convenience of use and implementation of the control device 13 which is accordingly free from disturbances and malfunctions generated by other control means and / or control. This independence and simplicity give the control device 13 a significant advantage over other existing control devices, more complex, incorporating many features and likely to malfunction.

The downstream temperature sensor 15 and the upstream temperature sensor 20 are interposed between a battery terminal 22 and a ground terminal 23 of a power supply source. A potential difference Ubatt is applied between the battery terminal 22 and the ground terminal 23. A first resistor R1 is interposed between the downstream temperature sensor 15 and the battery terminal 22 while a resistor R2 is interposed between the sensor temperature upstream 20 and the battery terminal 22. The upstream temperature sensor 20 is able to deliver an upstream voltage UT2 which is transmitted to the determination means 17 to adapt the threshold values VSmin, VSmax, which are respectively constituted in this example the minimum downstream temperature T1min and the maximum downstream temperature T1max of the airflow 3.

The determination means 17 transmit via a third resistor R3 to a first input terminal 24 of an operational amplifier 14 the reference voltage values Umin and Umax respectively corresponding to the threshold values VSmin, VSmax. Via a second input terminal 25 of the operational amplifier 14, the latter receives a voltage Um corresponding to said measured value VM to compare the voltage Um with the voltages Umin and Umax and supply an instruction voltage Ui to a control interface 26 of the compressor 9. The interface is capable of delivering a compressor voltage Uc which determines the nature of the starting or stopping of the compressor 9.

Such a control device 13 is of the simplest possible structure which gives it reliability and robustness optimized for a reliable and lasting control of the start and / or stop of the compressor 9, from the information 18 relating to an upstream temperature T2 of the air flow 3 measured upstream of the evaporator 12, said information 18 being representative of a thermal load affecting the evaporator 12, so that the thermal comfort provided by the said installation 1 is in correlation with a real, precise and iteratively updated nature of aerothermal parameters of the airflow 3 and / or relative parameters refrigerant FR and / or operating conditions of the evaporator 12.

Claims (13)

1. Control device (13) for controlling a fixed-capacity compressor (9) associated with an evaporator (12) through which an airflow (3) passes in a direction of flow (6) of the airflow (3), said compressor (9) and said evaporator (12) constituting an air-conditioning loop (8) of a motor vehicle heating, ventilation and/or air conditioning unit (1), said device (13) comprising a gage (15, 16) intended to measure a measured value VM of a characteristic C of a fluid FR,A and comparison means (14) for comparing the measured value VM of the characteristic C of the fluid FR,A with at least two threshold values VSmin, VSmax of said characteristic C, characterized in that said device (13) comprises an upstream temperature gage (20) intended to be positioned upstream of said evaporator (12) in said direction of flow (6) in order to measure an upstream temperature T2 of the airflow (3) and deliver an information item (18) which is taken into consideration by said device (13) in order to determine the threshold values VSmin, VSmax of said characteristic C.
2. Control device (13) according to the preceding claim, characterized in that said device (13) is a standalone device equipped with means (22, 23) of connection to a source of electrical power to operate the gage (15, 16) that measures said measured value VM and the upstream temperature gage (20).
3. Control device (13) according to either one of the preceding claims, characterized in that the comparison means (14) consist of an operational amplifier.
4. Control device (13) according to any one of the preceding claims, characterized in that the comparison means (14) are associated with determining means (17) for determining the two threshold values VSmin, VSmax of said characteristic C from the information item (18) relating to the upstream temperature T2 of the airflow (3).
5. Air conditioning loop (8) of a motor vehicle heating, ventilation and/or air conditioning unit (1), characterized in that said loop (8) comprises a control device (13) according to any one of the preceding claims.
6. Air conditioning loop (8) according to Claim 5, characterized in that the fluid FR,A consists of air A forming the airflow (3), the characteristic C consisting of a downstream temperature T1 of the airflow (3) measured downstream of the evaporator (12) in the direction of flow (6) of the airflow (3) through the latter (12), and in that the threshold values VSmin, VSmax consist of respective minimum T1min and maximum T1max values of said downstream temperature T1.
7. Air conditioning loop (8) according to Claim 5, characterized in that the fluid FR,A consists of a refrigerant FR circulating in said loop (8), the characteristic C consisting of a pressure P of said refrigerant (FR) inside the evaporator (12), and in that the threshold values VSmin, VSmax consist of respective minimum Pmin and maximum Pmax values of said pressure P.
8. Heating, ventilation and/or air conditioning unit (1) comprising an air conditioning loop (8) according to any one of Claims 5 to 7.
9. Unit (1) according to Claim 8, characterized in that said unit (1) comprises an inlet flap (7) for letting the airflow (3) into a housing (2) that forms part of the unit (1).
10. Unit (1) according to Claim 9, characterized in that the upstream temperature gage (20) is positioned downstream of said flap (7) in the direction of flow (6) of the airflow (3) in said unit (1).
11. Unit (1) according to Claim 9, characterized in that the upstream temperature gage (20) is positioned upstream of said flap (7) in the direction of flow (6) of the airflow (3) in said unit (1).
12. Method of implementing a control device (13) according to any one of Claims 1 to 4, characterized in that said method comprises a step of determining said threshold values VSmin, VSmax as a function of said information item (18) relating to the upstream temperature T2 of the airflow (3) taken upstream of the evaporator (12).
13. Method according to Claim 12, characterized in that said determining step is followed:

    - by a step of starting the compressor (9), if the measured value VM of the characteristic C is higher than the maximum threshold value Vmax, or

    - by a step of stopping the compressor (9) if the measured value VM of the characteristic C is lower than the minimum threshold value Vmin.

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