Method for checking the presence of incondensable gases in climate recovery and charging station

Abstract

Method of determining the presence of incondensable gases in a climate station cylinder for recharging motor vehicle air conditioning systems. One of the pressure sensors will be used that is present in the charging station and designed for monitoring the operations in the A/C system of the vehicle, placed on the low pressure LP and/or high pressure HP lines of the climate station, so that in case of verification of the incondensable gases, the control electronics opens a coolant charging valve and an HP/LP separating valve, thereby flooding the service pipes so as to receive the pressure signal from one of the service pressure sensors, LP or HP, of the station, and compare the value with the temperature T of the cylinder and check whether such pair of values is a corresponding parameter, without tolerances, of a pressure-temperature curve of the pure coolant.

Claims

1. Method for checking the presence of incondensable gases in a coolant contained inside a tank (11) of a climate recovery and charging station (20) for an air conditioning system (10) of a motor vehicle, said climate recovery and charging station (20) comprising a low pressure line (19) with a low pressure connection (16) that is connectable to an external low pressure connector (7) of the air conditioning system (10), a high pressure line (113) with a high pressure connection (14) connectable to an external high pressure connector (8) of the air conditioning system (10) and a pressure sensor (40) arranged on the low pressure line (19) and/or the high pressure line (113) and used to monitor the recovery and charging operations of the air conditioning system (10), said method comprising a step of measuring the temperature (T) of the coolant by a temperature sensor (45) integral with or mounted in proximity of said tank (11), wherein said method uses a control unit (50) that is configured to: open at least one shut-off solenoid valve (12) of an outlet pipe (13) connected to said tank (11) and open at least on separation valve (30) that is arranged on a branch line (33) between the low pressure line (19) and the high pressure line (113) so as to form a closed circuit (13, 113, 33, 19), once the circuit has been formed the coolant flows from the tank (11) through the outlet pipe (13), the high pressure line (113), the branch line (33), the low pressure line (19) and comes in contact with said pressure sensor (40) that measures the pressure (p) of the coolant, the control unit (50) checking whether the pair of pressure-temperature coordinates (p, T) detected from said pressure sensor (40) and from said temperature sensor (45) is on a liquid-vapor equilibrium line of said coolant, if the measured pressure (p) is higher than what it should be at the measured temperature (T) it means that there is a presence of incondensable gases within the coolant.

2. Station (20) for recovering and recharging coolant fluid from an air conditioning system (10) of a motor vehicle, with control unit (50) configured to operate according to the method set out in claim 1.

Description

BRIEF DESCRIPTION OF THE FIGURES

(1) This and other features will be more apparent from the following description of some of the embodiments, illustrated purely by way of example in the accompanying drawings.

(2) FIG. 1: generically shows a circuit diagram for connecting a charging station to the air conditioning system of a motor vehicle,

(3) FIG. 2: shows in detail the circuit diagram of an A/C charging station for motor vehicles, comprising a system configured to carry out the oil recovery as provided by the invention,

(4) FIG. 3: shows the pressure-temperature chart of the pure coolant,

(5) FIG. 4: shows the stratification inside the tank of the climate station.

DESCRIPTION OF THE INVENTION

(6) The present invention will now be described in detail with reference to the accompanying drawings to enable a man skilled in the art to implement and use it. Various modifications to the embodiments described will be immediately apparent to the man skilled in the art.

(7) With reference to FIG. 1, reference numeral 10 indicates an air conditioning or climate control system in a motor vehicle; it is installed in a vehicle and comprises a refrigeration circuit within which a coolant gas of predetermined type circulates at low pressure.

(8) The main components in said system 10 are: a compressor 4; a condenser 2 and a ventilation system 1; at least one coolant storage and dryer filter 3, an expansion valve 5; an evaporator 6.

(9) The compressor is the component designed to generate the pressure difference, a difference that allows the cycle to be repeated: in fact, it pumps the coolant fluid through the evaporator, where it evaporates at low pressure by absorbing heat from the outside, then compresses it and pushes it inside the condenser, where it condenses at high pressure by releasing the previously absorbed heat to the outside. The coolant fluid changes state inside the two heat exchangers: in the evaporator it changes from liquid to gaseous, in the condenser it changes from gaseous to liquid.

(10) The motor vehicle air conditioning system 10 also has two external terminals/connectors 7, 8 in low pressure (external low pressure connector) and high pressure (external high pressure connector), respectively, through which it is possible to recharge and/or recover the coolant gas through the connection with corresponding coupling devices of the climate station, or A/C station, in order to carry out the maintenance and recharge operations and other necessary checks.

(11) Again with reference to FIG. 1 and now also to FIG. 2, reference numeral 20 indicates a climate recovery and charging station comprising at least the following components: a coolant tank 11, or cylinder, a shut-off solenoid valve 12 for opening and closing at least one coolant fluid outlet pipe 13, HP, i.e. high pressure, connection, indicated with reference numeral 14, connectable in the respective high pressure branch 15 to the conditioning system 10, so as to be connected to the high pressure liquid coolant through the fitting/valve 8; an LP, i.e. low pressure, connection is also provided, which is identified by reference numeral 16, and connectable through the corresponding branch 17 to the conditioning system, in the fitting indicated with reference numeral 7 generally placed after the expansion valve; the coolant is in a gaseous state and at low pressure; a suction unit 18 that, through a compressor element, sucks/extracts the coolant from the conditioning system of the vehicle and sends it to tank 11 through pipes 19, so as to drain the system, a separation valve 30 of high and low pressure lines, a pressure sensor 40 on at least one of said high and low pressure lines, a temperature sensor 45 integral with, or alternatively mounted in the proximity of, said tank (11) for measuring said parameter, a solenoid valve 60 for draining the incondensable gas from the tank, at least one control and data processing unit/card 50 configured with said elements so as to receive the values thereof and manage the recovery, recharge steps and the operations required to implement the present invention.

(12) Substantially, once connected to the air conditioning system, the climate station carries out the following operations: The recovery of the coolant fluid present in the conditioning system, through the pipes for connection to the system of vehicle 15 and 17 and the respective valves 7 and 8; The filtering of the coolant fluid recovered; The injection of coolant fluid in the air conditioning system, on the high pressure HP valve side.

(13) Systems of the measurement of the mass associated with the tank may be provided, so as to monitor both the amount of coolant fluid recirculated and the amount subsequently injected in the air conditioning system.

(14) Further devices or features may be implemented in the control logic and the configuration of the processing and management unit of station 20, without departing from the scope of the present invention which, as said, relates to a procedure configurable in the control unit of station 20 capable to implement and allow full recovery of the oil at the end of the coolant recovery for its subsequent re-introduction during charging of system 10.

(15) The climate station 20 of the present invention, contrary to the stations of the prior art, is not provided with any pressure sensor connected to tank 11.

(16) The presence of valve 30 along with the operating logic of the control unit of station 20 allows determining the presence of incondensable gases inside the cylinder and possibly purging them, with a saving in terms of costs of the station while maintaining adequate reliability.

(17) The control unit 50 is in fact configured to operate without a dedicated pressure sensor on tank 11, which as said would be used only upon switch-on in order to assess the presence of incondensable gases in said tank.

(18) The control unit 50 instead uses one of the sensors (such as LP) already present in the charging station for monitoring the operations in the A/C system of the vehicle (it is in fact necessary to have one or two sensors on the LP and HP lines of the station in order to carry out a recovery cycle, since without the information relating to pressure in the system it is not possible to know when the recovery has finished).

(19) The method implemented by the control logic and configured in unit 50 is schematically shown with particular reference to FIG. 3, which shows the diagram of a typical low cost service station, i.e. provided with only one pressure sensor 40 on the LP line indicated with reference numeral 19.

(20) In essence, when the electronic control unit 50 wants to proceed to the verification of the incondensable gasesgenerally when switching on station 20 or at preconfigured time intervals on the same control unit, unit 50 opens the coolant charging valve 12 and valve 30 of separation of lines 19 and 30 (HP/LP), and makes the pure coolant flow from tank 11 and in liquid phase to the service pipes now configured as a closed circuit (indicated with reference numerals 19, 13 and 33); in this way, the fluid comes into contact with the low pressure sensor LP, that is, the sensor indicated with reference numeral 40 and serving the station, provided to monitor the progress of the coolant recovery and recharging operations.

(21) At this point, unit 50: Considering the temperature value T arriving from a dedicated temperature sensor 45 connected to tank 11 and Considering the pressure value measured by sensor 40 when the circuit is closed by valve 30 and line 33, Checks that the pair of pressure-temperature coordinates (P in 40, T 45) corresponds to that of the liquid-vapor equilibrium line of the pure coolant, an example of which is shown in FIG. 3.

(22) If such a coordinate pair does not correspond to that of the pure coolant line, that is, if the pressure measured by sensor 40 is greater than what it should be at temperature T, it means that there are incondensable gases and through the appropriate valve 60 on top of tank 11, they are purged, allowing an outflow of vapor phase which is mostly made up of airin fact, since air is lighter than the coolant vapor, stratification occurs as shown in FIG. 4.

(23) The opening of said valve 60 continues until the pressure-temperature pair (P in 40, T in 45) returns on the pressure-temperature curve of the pure coolant.

(24) At the end of the operations, the coolant charging valve 12 is closed and the gas present in lines 33, 19, 13 is recovered and then fed back into tank 11.

(25) At this point, the station is free of incondensable gases and the maintenance operations of the air conditioning system of the motor vehicle can be carried out.

(26) In this way, the advantage obtained was maintaining the incondensable gas venting feature at a significantly lower cost, since no dedicated pressure sensor for the cylinder is used. In contrast, the flooding and subsequent emptying of the pipes typically requires a penalty of 1-2 minutes, absolutely negligible considering that the draining of incondensable gases, as mentioned, is typically required not more often than every two weeks.

(27) In essence, the method for the verification of the presence of incondensable gases in a climate charging station 2 determines the presence of incondensable gases inside tank 11 of station 20 using one of the LP or HP sensors present in the charging station 20 and adapted to monitor the recovery and recharge of the A/C system of the vehicle; the control unit 50 opens at least one coolant charging valve and at least one valve of separation of the HP/LP lines, forming a closed circuit so that the coolant in the liquid phase and from tank 11 floods the service pipes 13, 19, 33 and comes into contact with the service pressure sensor 40 of station 20 which, connected to said unit 50, communicates the corresponding value thereof; as a function of said pressure and temperature value measured on tank 11, the unit processes and verifies the presence of incondensable gases.