WO2010007448A1

WO2010007448A1 - Automatic refrigerant leak detection system of indirect means for use on cooling and refrigeration units installed on vehicles and other transportation means.

Info

Publication number: WO2010007448A1
Application number: PCT/GR2009/000050
Authority: WO
Inventors: Theodoros Efthymiou
Original assignee: Individual
Current assignee: Individual
Priority date: 2008-07-14
Filing date: 2009-07-13
Publication date: 2010-01-21
Anticipated expiration: 2011-01-14
Also published as: GR1006642B

Abstract

A common cause of malfunction on cooling units is refrigerant leakage. Its diagnosis is done by technician during regular maintenance or, after most of the refrigerant has leaked. An indirect leak detection method on cooling units based on comparison of data for the critical operating parameters and their optimum values with the values measured. A device integrated in cooling units, applying the above method, measuring and monitoring the condensing and evaporating pressures and temperatures using sensors and comparing them with the optimal, according to an algorithm, can diagnose refrigerant leaks. A stand alone testing and diagnosing device applying the above method with upgraded open algorithm accepting variables input for the unit tested, that includes quick couplers to hook up to cooling units can reduce the diagnostic errors.

Description

DESCRIPTION OF INVENTION

AUTOMATIC REFRIGERANT LEAK DETECTION SYSTEM OF

INDIRECT MEANS FOR USE ON COOLING AND REFRIGERATION UNITS INSTALLED ON VEHICLES AND

OTHER TRANSPORTATION MEANS.

The invention relates to an automatic refrigerant leak detection system of indirect means designed to be used on air conditioning, cooling and refrigeration units installed on vehicles and other transportation means. For ease the air conditioning, cooling and refrigeration units will be referred to in the remaining text as cooling unit.

The cooling units contain refrigerants under high pressure. Cooling units installed on vehicles and other transport means and in general all those located in mobile sites often have problems due to leakage of refrigerant.

There are various leak detection methods, which can be divided into two categories.

1. Leak detection procedures that are performed/carried out by qualified technicians and require human presence, with typical methods:

• Leak check with the use of mechanical means, making the leak visually obvious (soapy water).

• Leak check with the use of special dyes, either alone or in combination with special ultraviolet lamp. • Leak check with the use of mobile electronic leak detection equipment that have electronic sensors for detecting the presence of refrigerant (corona, heated diode, etc.).

• Leak check with the use of ultrasonic equipment.

All the above require human presence. As a result these are applied only at the time of regular maintenance (during which a technician is present). The efficiency of this methods also depends on the capability of the technician and his capability to apply them efficiently. In addition in some units these techniques are carried out imperfectly due to the difficulty in accessing the entire circuit. 2. The ones carried out without the need of human presence that rely on stationary automatic leak control devices with typical methods:

• Automatic systems of leak detection which function with electronic sensors detecting refrigerant presence (sniffers).

• Spectroscopes These systems have high initial cost of construction and installation. In addition such systems are affected by external factors (such as, the flow of air, the change in relative humidity, the presence of lubricants and the presence of other gases). The typical cooling unit installed on vehicles and other transportation means is of small capacity and contains a relatively small amount of refrigerant. For this reason such expensive leak detection systems are not installed to prevent an increase in the cooling unit's cost. Nevertheless even if cost was of no issue, such units would operate inefficiently as the movement of the vehicle and the presence of lubricants would interfere with their function.

In practice, diagnosis of refrigerant leakage in cooling units installed on vehicles and other means of transportation takes place at the time of preventive maintenance or after most of the refrigerant has leaked and the unit's performance has been drastically reduced or it has even ceased functioning.

Cooling units are fitted with safety devices as well as control and monitoring systems for their operation. These include pressure switches or pressure sensors that are used in the low and high pressure branches to protect the compressor, and anti-frost thermostats to engage / disengage the compressor. The above control systems for car and other means of transportation cooling units, control individual pressures and temperatures in different parts of the circuit. Their tasks are to protect the circuit from operating with very low refrigerant charge or to ensure proper operation of the cooling unit. These switches and sensors are usually installed in series. It is therefore obvious that these give independent output signals, which control the activation or de-activation of the unit either as direct switches or indirectly through an algorithm.

In the event of leakage of a high percentage of the refrigerant, the pressure switches deactivate the cooling unit for its protection. The techniques and automations which exist today offer partial protection to the cooling unit from damage due to operation without refrigerant. Nevertheless today's automations neither protect the environment from leaked refrigerants nor the unit from the increased wear during operation in non- optimal conditions. In any case these do not protect the user from the loss of refrigerant, from the increased operating and maintenance costs due to non- optimal working conditions or from the consequences of cessation of operation of the cooling unit (eg destruction of perishable goods transported in a refrigerator). The automatic refrigerant leak detection system of indirect means designed to be used on air conditioning, cooling and refrigeration units installed on vehicles and other transportation means, refers to a device, which monitors the operating parameters of a cooling unit, and specifically monitors / controls the temperature and pressure conditions and revolutions of its parts, as described in detail below. The system estimates the amount of refrigerant within the cooling unit as a percentage of the optimum charging (specified by the manufacturer of the cooling unit) and produces a signal when the quantity is not within tolerance.

The proposed system eliminates the problem of late diagnosis of leak as

> due to its low cost it can be integrated in all refrigeration applications and as a result it offers prompt notification to the user.

> due to the indirect method of assessing the refrigerant charge it is not influenced by external factors (airflow, altitude, relative humidity, and presence of other gases) and as a result is more reliable than existing methods using refrigerant detectors. This system has advantages over today's existing safeguards since by combining and processing the data that is measured, improper functioning can be diagnosed timely thus protecting both the cooling unit's components from excess wear and damage and the environment from pollution.

The attached schematic diagram shows a typical form of vehicle cooling unit. The refrigerant is compressed in the compressor (3) and then passes through the condenser (4) where it is cooled and condensed with or without the use of a fan (1) by the air of the environment (A). The refrigerant continues the cycle (flow in accordance with the arrows) passes through the receiver dryer (6) and then expands passing through the expansion valve (7). In the heat exchanger (10) it evaporates absorbing heat from the recycled air (D) or the environment air (C) giving air conditioned air (E).

In this typical form of cooling unit are installed (or are utilized if available) some or all of the following sensors depending on the form and type of the cooling, refrigeration or air conditioning unit and its corresponding critical parameters as specified by the manufacturer:

> (2) External / environment air temperature sensor. This sensor is installed in the airflow before the condenser or condenser fan (1) and measures the temperature of the air supply to the condenser. The type of sensor and its mode of operation is not restrictive. A typical type is a sensor with resistance proportional to the temperature, either NTC or PTC . The sensor is used to measure the external temperature (A) and feed this information to the CPU. Usually such a sensor is available in vehicles and is used to inform the driver about the external temperature. > (5) Pressure sensor in high pressure branch. This sensor is installed in the high pressure branch of the cooling unit preferably before the receiver dryer (6). (This is not always possible since in some late model cooling units the manufacturers use a receiver dryer built-into the condenser (4)). The type of the sensor and its mode of operation are not restrictive. Today there are two types of sensors, both equipped with three wires. The first type uses one earth cable, a 5V volt input and an output that is proportional to the pressure. The second type creates a pulse that has a frequency that is proportional to the pressure. The sensor is used to measure the pressure in the high pressure branch of the cooling unit and feed this information to the CPU. In some late model vehicles such a sensor is available and its primary function is to activate the condensing fan and compressor. If the sensor is present its output can be fed to the CPU. In the rest of the vehicles that use a pressure switch (high / medium / low) the pressure sensor must be added. > (9) Evaporator temperature sensor. This sensor is installed in the flow of air from the evaporator (10). The type of sensor and its mode of operation is not restrictive. A typical type is a sensor with resistance proportional to the temperature, either NTC or PTC . The sensor is used to measure the temperature of the air leaving the evaporator (R) which is the temperature of evaporation and feeds this information to the CPU. Often such a sensor is available in the vehicle's cooling unit and it is used to control the de-icing of the evaporator. If the sensor is present its output can be fed to the CPU. In the rest of the vehicles that use temperature switches the temperature sensor must be added.

^ (11) Pressure sensor in the low pressure branch. This sensor is installed in the low pressure branch of the cooling unit between the evaporator (10) and the compressor. The type and mode of operation is not restrictive. Today there are two types of sensors, both equipped with three wires. The first type uses one earth cable, a 5V volt input and an output that is proportional to the pressure. The second type creates a pulse that has a frequency that is proportional to the pressure. The sensor is used to measure, the pressure in the low- pressure branch of the cooling unit and feed this information to the CPU. Such a sensor is not integrated in typical cooling units.

> (12) Temperature sensor for the monitoring of the temperature of the air conditioned space. This sensor is installed in the flow of air towards the evaporator (10). The type of sensor and its mode of operation is not restrictive. A typical type is a sensor with resistance proportional to the temperature, either NTC or PTC . The sensor is used to measure the temperature of the air entering the evaporator (E) and feed this information to the CPU. Usually such a sensor is available in vehicles and in refrigeration units and it is used for the recording of the temperature of the chamber (passenger cabin/ cold storage space). > (13) Engine speed sensor. The sensor is used to measure the RPM of the engine and feed this information to the CPU. Such a sensor is available in vehicles and it is used to control the engine.

These sensors (T), (5), (9), (11), (12) and (13) send signals to a central processing unit CPU (14). The CPU is integrated in the cooling unit and compares the measurements from the sensors (2), (5), (9), (11), (12) and

(13) with the stored data for the specific cooling unit as specified by the manufacturer of the cooling unit. By comparing the stored and measured data it is possible to estimate the refrigerant charge and the percentage (%) of deviation. It is possible to incorporate the algorithm in the existing CPU of the vehicle (CPU 13 and 14 are one and the same).

Attached follows the flow chart of the control algorithm for the CPU (Pg 2), which is further analyzed below. The numbering of the parts refers to the schematic diagram (Pg 3).

Step one, the critical operating parameters and their values are retrieved from the ROM of the CPU (time needed for the pressures to stabilize). The device verifies that the pressures of the cooling unit are balanced, as it is not possible to draw any conclusions at startup and before the pressures are balanced. On stabilization the sensor (2) reads the ambient temperature and the remaining critical operating parameters (compressor activation rate from CPU (13), cooled space temperature from sensor (12), etc.). The data is stored in the CPU as a function of the condensation temperature. The values corresponding to the condensation temperature that was measured by the sensor (2), of the other critical operating parameters are recovered from the

CPU (14). The high pressure measured by the pressure sensor (5) in the high pressure branch is compared to the stored data of the high pressure that corresponds to the condensation temperature measured.

If the high pressure measured is higher than normal it is not possible to have low charge and the only conclusions reached are auxiliary diagnostic conclusions as presented in the logical diagram. If the high pressure measured is normal or lower than normal, to determine whether there is insufficient refrigerant charge it is necessary to measure additional data that is then processed and compared with the stored specifications in step two.

Step two of the algorithm is to compare the data measured by the pressure sensor (11) in the branch of low pressure with the low pressure stored on the CPU No (14) that corresponds to the high pressure. If the low pressure is higher than the normal it is not possible to have low charge and the only conclusions reached are auxiliary diagnostic conclusions as presented in the logical diagram.

If the low pressure is normal or lower than normal not within the specifications range, it is necessary to measure additional data that is then processed and compared with the stored specifications in step three.

Step three of the algorithm is to compare the data measured by the evaporation temperature sensor (9) with the evaporation temperature stored on the CPU No (14) that corresponds to the low pressure. If the measured evaporation temperature is higher then the specifications the filling of the unit is insufficient and therefore a leakage has occurred.

As explained by comparing the above parameters measured by sensors (2, 5, 9, 11, 12, 13) with those specified by the manufacturer of the cooling unit, it is possible to estimate the amount of refrigerant within the cooling unit in relation to the optimum amount specified by the manufacturer of cooling unit using an algorithm. When the measurements are outside the manufacturer's specifications, the proposed leak detection system produces a signal which can be further processed to inform the user.

This invention combines the use of a CPU in the memory of which are stored the critical operating parameters, and their values specified by manufacturer for the operating conditions (engine speed) and compares them with data measured from two pressure sensors and two temperature sensors in order to diagnose a leak at its inception. The application of this invention is possible without significant cost in modern cars which include both external temperature sensor and internal temperature sensor (evaporation temperature). Manny also include pressure sensor for the monitoring of the high pressure. Their use, however, is limited to the management of the air conditioner components only (activate fans (1) and (8) and compressor (3)). The data acquired by these sensors are neither processed further nor combined. IN most cases their use is limited once fed to the CPU of the vehicle to the operating speed of the fans and the activation of the compressor.

With the proposed management of the data that is either already available or acquired from the sensors, and the data acquired by the added pressure sensor (11) in the branch of low pressure, it is possible to detect leakages at their inception (genesis). This is achieved by processing the acquired operating data of the cooling unit and comparing them with the stored, through the proposed algorithm.

The proposed automatic refrigerant leak detection method of indirect means designed to be used on air conditioning, cooling and refrigeration units installed on vehicles and other transportation means has a different set of parameters depending on the air conditioning unit in which it is integrated. The stored critical operating parameters such as type of refrigerant, engine revolutions in relation to compressor revolutions, refrigerant pressure in the high pressure branch, evaporator temperature, low pressure branch pressure, as a function of the condensing temperature, compressor activation rate for variable compressor etc are recovered and compared to the values of the critical operating parameters that are drawn from corresponding sensors during the unit's operation . The above example is not restrictive, since the algorithm can be operated with more data which need to be recorded as additional critical parameters. Other factors affecting the algorithm are the compression rate, the condensation rate, the type of refrigeration circuit/system, the type of compressor and the location of the sensors.

Following are given some examples which illustrate the importance of the above factors.

In the previous application of the invention, to optimize the outcome, requires data such as the engine revolutions and the vehicle speed. These parameters are important and must be taken into consideration. The data for these parameters can be (collected) recovered from the speedometer and the ABS of the vehicle.

Correspondingly in a car air-conditioning the temperature of the air- conditioned space varies only by 10⁰C. In addition the evaporation temperature varies greatly from the ambient temperature of the conditioned space. Therefore the ambient temperature is not a critical parameter. On the other hand in a refrigeration unit, the temperature inside the refrigeration chamber varies a lot and the fluctuation could be in the range of 60 ⁰C. The ambient temperature inside the refrigeration chamber is very close to the evaporation temperature. This has a significant impact to the optimum operation conditions and therefore the refrigeration chamber ambient temperature is classified as a critical parameter. The ambient temperature data can be measured by the temperature recording device of the refrigeration chamber.

Another example illustrating the modification of in the number and type of critical parameters (factors) depending on the cooling unit is the parameter "activation rate of a variable compressor". So far there are no refrigeration units that operate with variable compressors and therefore the parameter percentage of compressor activation is not a critical parameter since it is fixed and equal to 1.

The algorithm discussed and analyzed above is presented in detail in the attached flowchart. The sensors that were selected are of piezoelectric type, which have an output voltage proportional to the pressure of the refrigerant in the unit's branch. Sensors that operate with a pulse could also be used, as the type of sensor is not essential characteristic of the invention. As a result the type of sensors that can be used is not limited to the above mentioned types, since any type of data can be processed to monitor the pressure. Similarly, the temperature sensors used are of variable resistance type with positive or negative response (PTC or NTC). The position that the sensors are installed for the of measuring of the condensation and evaporation temperature is not essential characteristic of the invention, neither is the type of sensors used limited in the above mentioned types, since any type of data can be processed to monitor the operating temperature.

The data of the manufacturer's specifications and the critical operating parameters are stored sorted by condensation temperature. The data of the remaining values (high-pressure branch pressure, evaporation temperature and low pressure branch pressure) depend on the condensation temperature. These data instead of being stored in a data base can alternatively be produced by an algorithm, either in the form of self teaching algorithm, or in the form of function (simulation).

The condensation temperature measured is related to the corresponding stored data. From the stored data for the specific temperature the values of the other parameters are drawn. These are compared to the values measured by the sensors. From this comparison the algorithm draws conclusions regarding the filling of the cooling unit with refrigerant and the percentage (%) off loss is estimated. Any conclusion of loss greater than the considered by the manufacturer as normal, for this cooling unit, is evaluated as leak and a signal is given out by the system. This signal can be further processed. (As an indication, depending on the size of the cooling unit and its use, it could be triggering an alarm, or activate a warning lamp, etc.).

To monitor the cooling unit it is necessary for the unit to be operating.. If the cooling unit is inactive for a long period the proposed automatic leak detection system of indirect means in cooling unit may include a mechanism that activates the cooling unit at regular intervals, for the necessary time to balance the pressures and to take the necessary measurements. (The interval between two successive activations, the minimum operating time etc. data, is recorded in the database as critical factors of operation). The advantage of this invention is that it combines the data, which is available from the sensors with the cooling unit's manufacturer's specifications. Making comparisons the algorithm estimates the refrigerant charging, as a percentage of the optimum fill (specified). Based on the results it can diagnose a leakage and predict the complete deactivation of the cooling unit before it occurs. The early detection of refrigerant leakage is very important since the diagnosis of the leakage results in limiting the quantities of refrigerants released into the atmosphere. All refrigerants used today contribute to the greenhouse effect. Therefore by reducing the refrigerants that are released into the environment we limit the greenhouse effect. In addition to the environmental impact early diagnosis of leak is beneficial for the consumer / end user of the cooling unit in many ways.

S he is protected from the loss of the refrigerant. *f he can program a timely repair before the cooling unit stops working, therefore the reliability of the device is increased.

S the products stored are protected from possible deterioration which they would have suffered if there was insufficient cooling due to faulty operation or emergency shut-off.

The automatic refrigerant leak detection method of indirect means applicable to air conditioning, cooling and refrigeration units installed on vehicles and other transportation means at the same time can serve as a device to verify the correct filling of the cooling unit with refrigerant during the periodic maintenance. In the case of improper filling, the craftsman will receive an error signal. He can then correct the problem immediately, and when used in this manner it can be considered as a diagnostic tool.

A stand alone multy parameter automatic refrigerant leak detection device of indirect means for cooling units can serve as a repair and maintenance tool for cooling units. Used in cooling units that do not have it built in, it can diagnose problems, being a useful tool for repair and maintenance. This device would have to include two temperature sensors to be placed respectively in the flow of air into a condenser and the evaporator by the technician performing maintenance and two quick couplers to be connected to the low and high pressure charging ports. Fom the ports the pressure sensors will receive the information for the pressure in the high and low pressure branch of the cooling unit. It would also have to be connected to the central processing unit of the vehicle / transportation mean to receive data such as engine speed and the percentage (%) of activation of the compressor. Attached follows the logical diagram of the operation of the control algorithm of the stand alone multy parameter maintenance tool (Pg 4), the analysis of which is identical with that of the above indirect leak detection device with the only difference being the output of warning signs for any malfunction. The numbering of the parts relates to the schematic diagram (Pg 3).

Claims

1. An automatic refrigerant leak detection method of indirect means applicable to air conditioning, cooling and refrigeration units installed on vehicles and other transportation means, which function with refrigerant that is compressed in a compressor (3), cooled and condensed in a condenser (4) with or without the use of a fan (1), expanded and evaporated in evaporator (10) absorbing heat. For the control of such a cooling unit pressure (5) and temperature (2, 9) switches or sensors are used. The method is characterized by:

> Integration in the cooling unit of pressure (5, 11) and temperature (2, 9) sensors to take measurements. It is possible to use any existing sensors that are compatible.

> Registration in a CPU (14) of the necessary time, from cooling unit's startup, for the pressures to reach equilibrium. The value of the time from startup until the pressures are stabilized is specified by the manufacturer of the cooling unit. > Registration in a CPU (14) of the critical parameters of operation, as specified by the manufacturer of the cooling unit, their optimum values of operation and their permissible range. The critical parameters are:

• The time from startup until the stabilization of the pressures in the cooling unit.

• The temperature of the air that is cooling the condenser, (used to specify the value of the parameters that depend on temperature)

• The pressure in the high pressure branch (condensation pressure) and its values as a function of the temperature of the air supply to the condenser.

• Pressure in the low pressure branch (evaporation pressure) and its values as a function of the pressure in the high pressure branch (condensation pressure) and the temperature of the air supply to the condenser. • Evaporation temperature and its values as a function of the pressure in the high pressure branch (condensation pressure), the pressure in the low-pressure branch (evaporation pressure) and the temperature of the air supply to the condenser.

> Verification of the stabilization of the pressures in the cooling unit. This verification is carried out by comparing the time registered in the CPU as necessary to reach equilibrium, with the time elapsed since the startup of the cooling unit.

> Monitoring of the values of the critical parameters of operation of the cooling unit. The values of the parameters are measured by pressure (5, 11) and temperature (2, 9) sensors. The measured data is fed to the central processing unit CPU (14).

> Retrieval of the stored optimal operation values of the cooling unit's critical operating parameters, according to its manufacturer's specifications and their permissible range, by the central data processing unit CPU

> Hierarchy comparison by the central processing unit CPU according to algorithm, of the measured values of the critical operating parameters with those registered in the CPU, specified by the manufacturer of the cooling unit This hierarchical comparison consists of the following specific comparisons to the following chronological sequence.

• Comparison of the measured pressure from the high pressure sensor (5) to the corresponding value registered in the CPU for the current temperature conditions of the air supplied to the condenser. The correspondence is achieved by matching the temperature of the air supply to the condenser measured by the temperature sensor

(2).

• Comparison of the low-pressure measured by the pressure sensor (11) to the corresponding value registered in the CPU for the current pressure conditions in the high pressure branch. The correspondence is achieved by matching the pressure in the high pressure branch measured by the sensor (5).

• Comparison of the evaporation temperature measured by the temperature sensor (9) to the value registered in the CPU for the current operating conditions in the high and low pressure branch.

• Assessment of the refrigerant charge inside the cooling unit from the central processing unit CPU. Derive of conclusion regarding the existence of a leak.

• Exit diagnostic message, Automatic refrigerant leak detection method of indirect means applicable to air conditioning, cooling and refrigeration units installed on vehicles and other transportation means in accordance with claim 1, further characterized by:

> In the cooling unit a sensor is integrated that monitors the compression rate. It is possible to use an existing sensor, if available. > The additional critical parameter "rate of compression of the compressor" is recorded in the CPU.

> The value of the additional critical parameter is monitored by the compression sensor (13) and the measured data is supplied to the central processing unit CPU (14).

> Comparisons according to claim 1,

• The optimum high pressure value registered in the CPU is compared with the corresponding measured by the sensor (5). The optimum high pressure value registered is additionally related to the current rate of compression.

• The optimum low pressure value registered in the CPU is compared with the corresponding measured by the sensor (11). The optimum low pressure value is additionally related to the current rate of compression. • The optimum evaporation temperature value registered in the

CPU is compared with the corresponding measured by the temperature sensor (9). The optimum low pressure value is additionally related to the current rate of compression.

Automatic refrigerant leak detection method of indirect means applicable to air conditioning, cooling and refrigeration units installed on vehicles and other transportation means in accordance with claims 1 and 2 additionally characterized by.

> In the cooling unit a temperature sensor in the evaporator (12) is integrated that monitors the temperature of the air supply to the evaporator. It is possible to use an existing sensor, if available.

> The additional critical parameter "temperature of the air supply to the evaporator" is recorded in the CPU.

> The value of the additional critical parameter is monitored by the temperature sensor of the air supply to the evaporator (12) and the measured data is supplied to the central data processing unit CPU (14).

> Comparisons, according to claims 1 and 2.

• The optimum high pressure value registered in the CPU is compared with the corresponding measured by the sensor (5). The optimum high pressure value registered is additionally related to the temperature of air supplied to the evaporator.

• The optimum low pressure value registered in the CPU is compared with the corresponding measured by the sensor (11). The optimum low pressure value is additionally related to the temperature of air supplied to the evaporator. • The optimum evaporation temperature value registered in the CPU is compared with the corresponding measured by the temperature sensor (9). The optimum low pressure value is additionally related to the temperature of air supplied to the evaporator.

4. Automatic refrigerant leak detection method of indirect means applicable to air conditioning, cooling and refrigeration units installed on vehicles and other transportation means in accordance with claims I₅ 2 and 3 further characterized by:

P- In the cooling unit an altitude sensor is integrated that monitors the altitude of flight. It is possible to use an existing sensor, if available.

> The additional critical parameter "altitude of flight" is recorded in the CPU. > The value of the additional critical parameter is monitored by the altitude of flight sensor and the measured data is supplied to the central processing unit CPU (14).

> Comparisons, according to claims 1, 2 and 3.

• The optimum high pressure value registered in the CPU is compared with the corresponding measured by the sensor (5). The optimum high pressure value registered is additionally related to the altitude of flight.

• The optimum low pressure value registered in the CPU is compared with the corresponding measured by the sensor (11). The optimum low pressure value is additionally related to the altitude of flight.

• The optimum evaporation temperature value registered in the CPU is compared with the corresponding measured by the temperature sensor (9). The optimum evaporation temperature value is additionally related to the altitude of flight.

5. Automatic refrigerant leak detection method of indirect means applicable to air conditioning, cooling and refrigeration units installed on vehicles and other transportation means in accordance with claims 1,2,3 and 4 additionally characterized by:

> An automation is integrated in the cooling unit that initiates the operation of the unit when the time the unit is inoperative exceeds the maximum interval between two startups.

> The additional critical parameter "maximum interval between two successive starts" is recorded in the CPU as well as its value specified by the manufacturer of the cooling unit.

6. Automatic refrigerant leak detection method of indirect means applicable to air conditioning, cooling and refrigeration units installed on vehicles and other transportation means in accordance with claims 1,2,3 ,4 and 5 additionally characterized by the fact that applies to any form of cooling unit and not only on cooling units installed / operated on vehicles or means of transport.

7. Automatic refrigerant leak detection device of indirect means which implements the above method of claim 1 applicable to air conditioning, cooling and refrigeration units installed on vehicles and other transportation means operating with refrigerant gas that is compressed in a compressor (3), cooled and condensed into a condenser (4) with or without the use of a fan (1), expanded and evaporated in evaporator (10) absorbing heat. Characterized by

> CPU to make comparisons, store data and produce signals.

> Pressure sensors (5, 11) installed in the branch of low pressure (11) and high pressure (5), connected to the CPU feeding signals / data proportional to the pressure within the branch. > Temperature sensors (2, 9) installed in the flow of the supply air to the condenser (2), and the flow from the evaporator (9) connected to the CPU feeding signals / data proportional to the monitored temperatures.

> Algorithm in accordance with claim 1, 5. > Extracting conclusions

8. Automatic refrigerant leak detection device of indirect means which implements the above method of claim 2 applicable to air conditioning, cooling and refrigeration units installed on vehicles and other transportation means in accordance with claim 7, additionally characterized by the fact that:

> Integrates in addition a compression rate sensor on the compressor connected with the CPU that transfers data concerning the rate of compression of the compressor. > Utilizes algorithm according to claim 2, 5.

9. Automatic refrigerant leak detection device of indirect means which implements the above method of claim 3 applicable to air conditioning, cooling and refrigeration units installed on vehicles and other transportation means in accordance with claim 7, 8 additionally characterized by the fact that : > Integrates in addition an air temperature sensor (12) connected with the CPU that transfers data concerning the temperature of the air supply to the evaporator.

> Utilizes algorithm according to claim 3, 5.

10. Automatic refrigerant leak detection device of indirect means which implements the above method of claim 4 applicable to air conditioning, cooling and refrigeration units installed on vehicles and other transportation means in accordance with claim 7, 8, 9 additionally characterized by the fact that :

> Integrates in addition an altitude sensor connected with the CPU that transfers data concerning the altitude of flight.

> Utilizes algorithm according to claim 4, 5.

11. Automatic refrigerant leak detection device of indirect means which implements the above method of claim 6 applicable to air conditioning, cooling and refrigeration accordance with claim 7, 8, 9, 10 additionally characterized by the fact that :

> The device is integrated to a cooling unit that is installed in any form of controlled temperature chamber and not only in air conditioning, cooling and refrigeration units installed on vehicles and other transportation means

12. Method for controlling the operation and for diagnosis of malfunctioning in cooling units which applys to any form of cooling unit on transportation means which operates with refrigerant gas that is compressed in a compressor (3), cooled and condensed into a condenser (4) with or without the use of a fan (1), expanded and evaporated in evaporator (10) absorbing heat. For the control of the cooling unit measurements are taken by pressure (5) and temperature (2, 9) sensors. The method is characterized by the following steps:

> Connection to the cooling unit pressure (5, 11), temperature (2, 9, 12) and compression rate sensors

> For all the types of cooling units, registration in a CPU (14) of the time necessary for the pressures to balance from cooling unit's startup. The value of the time from startup to reach equilibrium of pressures is specified by the manufacturer of cooling unit.

> For all the types of cooling units, registration in a CPU (14) of the critical parameters of operation proposed by the manufacturer of the cooling unit, the optimum values of operation and the permissible range. The critical parameters are: • Time needed from startup of in the cooling unit for the pressures to be balanced.

• Temperature of air supply to the condenser.

• Pressure in the high pressure branch (condensation pressure) and its values as a function of the temperature of the air supply towards the condenser.

• Pressure in the low pressure branch (evaporation pressure) and its values as a function of the pressure in the high pressure branch (condensation pressure) and temperature of the air supply to the condenser.

• Evaporation temperature and its values as a function of pressure in the high pressure branch (condensation pressure), the low- pressure branch (evaporation pressure) and the temperature of the air supply to the condenser. • Temperature of the air supply to the evaporator

• The rate of compression of compressor

> Verification that the cooling unit has reached a state of balace of pressures. The verification is carried out by comparing the time registered in the CPU as necessary to reach equilibrium, with the time elapsed since the startup of the cooling unit.

> Monitoring of the values of the critical parameters of operation of the cooling unit by pressure (5, 11) and temperature (2, 9, 12) sensors and feeding the measured data to the central processing unit CPU (14). > Retrieval of stored optimal operation values for the cooling unit according to manufacturer's specifications of the above mentioned critical operating parameters and their permissible range, by the central processing unit CPU

> Hierarchy comparison of the measured values of the critical operating parameters with those registered in the CPU specified by the manufacturer of the cooling unit from the central processing unit CPU according to algorithm. This hierarchical comparison consists of the following specific comparisons to the following chronological sequence. • Comparison of the measured pressure from the high pressure sensor (5) to the corresponding value registered in the CPU for the current temperature conditions in the air supplied to the condenser. The correspondence is achieved by matching the temperature of the air supply to the condenser measured by the temperature sensor (2). • Comparison of the low-pressure measured by the pressure sensor (11) to the corresponding value registered in the CPU for the current pressure conditions of high pressure. The correspondence is achieved by matching high pressure measured by the sensor (5). o Draw conclusions for malfunction of the compressor, problem in the filter or the condenser and existence of leakage

• Comparison of the evaporation temperature measured by the temperature sensor (9) to the value registered in the CPU for the current operating conditions of pressure in the high and low pressure branch. o Draw conclusions on malfunction of the expansion valve and existence of leakage >^• Exit diagnostic message.

13. Portable testing and diagnostic tool for detecting leakages and repair and maintenance tool that implements the above method of claim 12 applicable to any form of cooling unit for transport means operating with refrigerant gas that is compressed in a compressor (3), cooled and condensed into a condenser (4) with or without the use of a fan (1), expanded and evaporated in evaporator (10) absorbing heat, characterized by

> CPU that contains/stores data of values of operating parameters, receives signals from sensors, performs comparisons between stored and received data, draws conclusions and gives signals.

> Keyboard for the selection of the system being checked, in order to retrieve the manufacturer's specifications.

^ Includes couplers to connect the mobile device and its sensors to the cooling unit for reading the data. >^> Pressure sensors (5, 11) to monitor the pressures in the low (11) and high pressure (5) branch, connected with the CPU producing signals depending on the pressure within branch.

> Temperature sensors (2, 9, 12) to be placed in the flow of air supplied to the condenser (2), the evaporator (12) and the air supply of the evaporator (9) to send signals proportional to the temperatures to the CPU. > Algorithm according to claim 12.

> Draw conclusions on the operation of the cooling unit compared to the manufacturer's specifications for optimum performance.

> Draw conclusions on malfunctions, technical problems and refrigerant leaks. >^■ Processing of conclusions and export message.