IT201600122237A1 - COOLING SYSTEM OF AN INTERNAL COMBUSTION ENGINE - Google Patents

Description

"COOLING SYSTEM OF AN INTERNAL COMBUSTION ENGINE"

Field of the invention

The present invention relates to a cooling system for internal combustion engines.

Description of the prior art

Conventionally, pressurization systems concentrate the pressurization on the air side of the expansion tank. It is indirect pressurization. The coolant pressure level will increase as the passive pressure in the air expansion tank increases based on the coolant temperature and coolant pump-induced coolant recirculation.

Indirect pressurization is slow and uncontrollable. It would be helpful if the pressurization was faster and more controllable than the indirect (traditional) pressurization.

Summary of the invention

Therefore a main object of the present invention is to provide a cooling circuit which overcomes the above drawbacks / problems through direct pressurization of the cooling circuit.

The advantages of direct pressurization consist in the fact that it is independent of the activation of the coolant circulation pump and of the heat produced by the internal combustion engine, therefore good pressurization can be obtained even when the engine is cold started.

The main idea of the present invention is to replace the expansion tank with an auxiliary pressurization unit comprising a cylinder / piston in which the cylinder is in communication with the cooling circuit. Therefore, the movement of the piston in its cylinder allows to obtain a direct pressurization of the circuit which is achieved without the contribution of air.

An actuator is coupled to the piston to control its displacement. Furthermore, an electronic control unit is configured to control such an actuator. Preferably, this electronic control unit coincides with the one responsible for controlling the internal control unit.

According to a preferred embodiment of the invention, the pressure in the cooling circuit is controlled by the cylinder / assembly, therefore the displacement of the piston is controlled to produce a target pressure in the cylinder chamber and therefore in the cooling circuit; to reduce the pressure both in the cylinder chamber and in the cooling circuit; to suck the refrigerant from a tank to fill the cooling circuit both to compensate for the lost refrigerant and to vary the amount of refrigerant in the cooling circuit according to the operating conditions.

According to a preferred embodiment of the invention, the piston is equipped with an elastic buffer to minimize pressure peaks in the cooling circuit.

According to another preferred embodiment of the invention, the auxiliary pressurization assembly comprises a coolant reservoir connected to the cooling circuit and the cylinder / piston referred to above through a three-way valve in which a first port of the three-way valve vie is connected directly to the cooling circuit, preferably on the suction pipe, a second port is connected directly to the cylinder / piston assembly and a third port is connected directly to said coolant tank.

Preferably, said electronic control unit is configured to also control said three-way valve to carry out different procedures for controlling the state of the cooling circuit and of the auxiliary system.

A further object of the invention is a method for operating the pressurization system for venting, filling and pressurizing the cooling circuit according to the second embodiment described in the following detailed description. These and other objects are achieved by means of the attached claims which describe preferred embodiments of the invention which form an integral part of the present description.

Brief description of the drawings

The invention will become clearer from the following detailed description given by way of non-limiting example to be read with reference to the figures of the attached drawings in which:

Figure 1 schematically shows a first embodiment of the cooling system according to the present invention;

Figure 2 schematically shows a second embodiment of the cooling system according to the present invention;

Figure 3 schematically shows in greater detail a portion of Figure 2 and the related control means.

The same reference numbers and letters in the figures indicate identical or functionally equivalent parts. According to the present invention, the expression "second element" does not imply the presence of a "first element", first, second, etc. are used only to improve the clarity of the description and should not be interpreted in a limiting way.

Detailed description of the preferred embodiments

A cooling circuit of an ICE internal combustion engine usually comprises a pump P driven by the crankshaft of the combustion engine or by an electric drive unit, a radiator R suitable for dispersing the heat into the environment and finally a fan (not shown) suitable for increasing the convection effects of such heat dispersion.

At least one pipe P1 conveys the hot coolant from the internal combustion engine to the top of the radiator R and at least one other pipe called the second pipe P2 connects a lower part of the radiator to the pump P. Usually, the pump is placed directly on the block of combustion engine, therefore no other pipes are described however another pipe / passage connects the pump to the internal combustion engine.

Figure 1 describes an example of implementation of the present invention.

The second tube P2 is in hydraulic communication with a cylinder / piston assembly CPA through tube P3 in a T configuration with the second tube P2.

The piston PS is movably coupled to its cylinder C. The chamber CH formed between the piston and the cylinder is in hydraulic communication with the cooling circuit CC through the second tube P3. Hereinafter, this cylinder chamber is also referred to as the coolant chamber.

An actuator A controls the displacement of the cylinder piston, therefore when the cooling circuit is sealed, the displacement of the piston varies the pressure inside the cooling circuit itself.

The actuator can be an electric drive unit or a pneumatic actuator. The opposite face of the piston PS facing the coolant chamber CH can be subjected to a pneumatic action to control its movement inside its cylinder.

According to a preferred embodiment of the invention, a surface of the chamber facing the piston is provided with a bearing B to avoid pressure peaks.

According to a preferred embodiment of the invention, a pressure sensor PS, such as a piezoelectric sensor, is also associated with the cooling circuit, for example, it can be coupled to the coolant chamber CH of the cylinder or along the third tube P3 which connects the CPA assembly to the tube 2.

According to the invention, the pressure within the circuit is monitored continuously when the ignition is ON and the actuator A is controlled accordingly to maintain the pressure above a predetermined threshold and preferably within a preferably predefined range of pressures. .

When the piston reaches a second position corresponding to the smallest volume of the CH coolant chamber and the pressure is still below said predefined range, a warning is sent to the vehicle's dashboard to notify the driver that there is a coolant / liquid leak. refrigerant in the circuit.

A contact sensor or any other suitable displacement sensor DS for sensing the piston position may be implemented by one skilled in the art. It can be coupled to the piston rod or it can be a per se known Hall sensor.

According to a preferred embodiment of the invention, when the ignition switches from ON to OFF, the piston is moved to a second position corresponding to the maximum volume of the chamber CH.

This operation ensures that an operator who opens the cooling circuit does not get injured and allows correct filling of the circuit.

Figure 1 describes an electronic control unit ECU which monitors the pressure and which controls the actuator A which coincides with the engine control unit, i.e. the electronic control unit which controls the internal combustion engine ICE. However, an independent electronic control unit can be implemented. For example, according to the present invention, it is possible to conceive a kit for updating traditional cooling circuits in such a way that it is sufficient to connect the cylinder C with the cooling circuit at the hydraulic level and the control unit with the vehicle battery and with an electric cable that is live when the ignition is ON.

Figure 2 describes a second embodiment of the present invention.

As regards the previous embodiment, ICE represents an internal combustion engine and R a radiator for dissipating the heat in the environment produced by said internal combustion engine.

The first pipe P1 connects an upper portion of the radiator to the ICE.

The second pipe P2, on the other hand, connects a lower portion of the radiator with a pump P which draws coolant from the radiator to cool the ICI.

The third tube P3 is connected, at one end, to the second tube P2 in a T-connection and, at a second end, to a first port of a three-way valve P1.

A second port of the three-way valve is connected, through the fourth pipe 4, to the refrigerant chamber CH of a pressure piston PS and a third port of the three-way valve is connected to a lower portion of a refrigerant tank T through the fifth tube P5.

According to condition a) of the three-way valve, the fourth pipe P4 and the fifth pipe P5 are in communication with each other, while according to condition b) of the three-way valve, the third pipe P3 and the fourth pipe P4 are in communication between them.

Preferably, a first non-return valve FVV bypasses the three-way valve P1 which connects the pipes P4 and P5. If the engine is off, the piston can suck fresh coolant from the tank without passing valve V1 in said condition a). This means that instead of a three-way valve it is possible to implement a simple two-way valve on the P4 pipe by installing the non-return valve on the P5 pipe and inserting a T-connection in place of the three-way valve.

Furthermore, a sixth tube P6 connects an upper portion of the ICE with an upper portion of the tank to allow deaeration of the ICE and a seventh tube P7 connects an upper portion of the radiator R to said upper portion of the tank T to allow deaeration of the ICE. radiator.

A second valve V2 is preferably arranged on said sixth tube P6 and a third valve V3 is preferably arranged on said seventh tube P7.

Preferably, the relief valve SPRV bypasses said third valve V3 allowing the radiator to discharge the medium into the tank T in the event of overpressure in the radiator.

Regarding the previous embodiment, when the piston is in the minimum displacement, the coolant chamber CH has the maximum size and vice versa when the piston is in the maximum displacement the coolant chamber CH has the minimum size. According to this second embodiment, the ECU is programmed to develop at least one of the following operations:

if the engine is on the three-way valve it is switched to said condition b) and the piston regulates the pressure in said cooling circuit above the above threshold or within the above interval. The three-way valve is then switched into said condition a) as long as said detected pressure is above said threshold or within said range of pressures.

When the ignition is switched from ON to OFF, the three-way valve is switched in said condition b) and the piston is released towards said minimum displacement to depressurize the cooling circuit to ambient pressure for the reasons set out above.

When the ignition is switched from on to off, an air detection procedure is performed: the valve V1 assumes this condition b) and the piston moves towards the maximum position. The PR pressure sensor detects the pressure in the DC cooling circuit. The ECU compares the pressure variation with the force exerted by the piston on the cooling circuit and evaluates the amount of air in the cooling circuit as the air is compressible.

If the amount of air exceeds a predetermined threshold, a vent / deaeration procedure is performed.

The bleeding procedure mainly depends on the presence of one of the P6 and P7 branches or both.

According to the bleed procedure, the valve V1 assumes the condition a) therefore the piston moves towards its minimum displacement. This implies that it sucks refrigerant from the tank T. Then P1 goes into condition b) and the valve V2 and / or V3 is / are open / open, while the piston moves towards its minimum displacement, therefore the air is pushed by the engine and / or from the radiator to the tank. Then valves V2 and V3 are closed and kept closed.

After the vent procedure, which can be performed for one or both branches, in parallel or in succession, the air detection procedure is performed again and finally the vent procedure is repeated for one or both branches . In the event that the air detection procedure does not detect air in the cooling circuit, at least when the engine is started, the piston is controlled in a closed loop control to maintain a target pressure in the cooling circuit as long as the engine is running. After the stabilization of the pressure in the cooling circuit, the valve 1 could be made to pass into said condition a) disconnecting the piston from the cooling circuit.

When the ignition switch is turned to the "ON" position and the engine is not running, the ECU performs a piston reset: the ECU detects the piston position and in case it is outside the range of positions predetermined, preferably arranged at the center with respect to the entire piston displacement, the valve V1 is switched to condition a) and the piston is displaced to reach said predetermined interval. This procedure allows the piston to be kept in an intermediate position throughout its stroke so that it is controlled to compensate positively or negatively the pressure variations detected in the DC cooling circuit.

To avoid the opposite situation where the piston is close to its minimum displacement condition, the displacement to the minimum displacement condition while drawing refrigerant from the tank can be appropriately limited.

In any case, the piston "centering" operation in the above position range can be achieved by opening one of the above V2 / V3 valves or both as described in the above bleeding procedure and moving the piston towards said intermediate position.

Figure 3 shows an example of a piston operated by means of the pneumatic circuit of the vehicle. Heavy vehicles are usually equipped with a pneumatic circuit to control the vehicle's brakes and / or suspension.

Therefore Figure 3 shows a preferred embodiment of the invention which can be combined with the one described above according to the embodiment of Figure 2.

The piston described is pneumatically controlled and is of the double action type. In particular, it has a first coolant chamber or chamber CH in communication with the cooling circuit as in Figures 1 or 2 and a left chamber LC and a right chamber RC separated from the left chamber by a central fixed partition.

Therefore the piston is a double piston with two movable pistons interconnected by a plunger. The left mobile piston defines, on the face towards the piston, said left chamber LC and on the opposite face it compresses refrigerant in the first chamber CH.

The left chamber LC communicates operationally with a source of pressurized air such as the above compressed air circuit through the valve PV. The right chamber is also in communication with the source of pressurized air through the VV valve.

In the left chamber a Psens pressure sensor is arranged and operatively associated with the control unit ECU. A pressure sensor Vsens is also arranged in the right chamber and operatively associated with the control unit ECU.

The ECU is also configured to control the PV and VV valves based on the pressure values measured by the PR sensor alone or also based on the Psens and Vsens measurements, first to pressurize the DC cooling circuit when the engine is running or to perform the above air detection and vent / deaeration procedures or said piston reset.

Figure 3 also shows the pressure sensor PR associated with the cooling circuit; and the displacement sensor DS as described above. It can be of any type, for example it can determine the position of the double piston together with the entire displacement of the piston or it can detect the piston only in predefined positions, for example an intermediate "centering" position along the entire movement of the double piston.

The valve VV is of the two-position type and is suitable, in a first position (from above), to connect the right chamber with the source of pressurized air AS to increase the pressure in the right chamber RC with the result of depressurizing the chamber left LC and the cylinder or the chamber of the refrigerant CH or according to a second position (neutral) connect the right chamber with the environment "am" (vent). The PV valve has three positions. The first position (from the top) connects the left LC chamber with the environment (vent) and the pressure source is closed tightly; the second position (neutral) blocks all doors, therefore the left chamber and the pressure source are closed tightly; the third position connects the left chamber and the pressure source AS to pressurize the left chamber LC and therefore the chamber of the cylinder CH.

Figure 3 is represented according to the standard convention on pneumatic drawings, therefore it is itself clear to one skilled in the art.

According to the present embodiment, when the ignition is off, the engine is not running and the three-way valve V1, described in figure 2, assumes said position b), therefore it puts in communication the refrigerant chamber CH of the cylinder a pressure with the cooling circuit DC and the pressure valve PV is in the (second) neutral position while the valve VV is also in its (second) neutral position.

The pressure in the left chamber, also called "chamber side pressure", can only be released by means of a pressure relief valve PRV1 in communication with the left chamber, instead the pressure in the right chamber RC is reduced to atmospheric pressure.

When the ICE internal combustion engine is hot and is turned off, the temperature can rise, therefore the pressure in the cooling circuit causes the cooling chamber CH to increase and the PS piston to move towards its minimum displacement position. The air pressure in the left chamber increases, the septum being fixed. If this exceeds the opening pressure of the pressure relief valve PRV1. However, despite the opening of this bleed valve, the pressure of the DC cooling circuit continues to increase even after reaching the minimum piston displacement, the pressure relief valve described above SPRV opens bypassing said third valve V3 and allowing the radiator to drain the medium into the tank T, therefore the pressure builds up in the coolant tank T.

The size of the water tank T is preferably designed and filled with coolant so that all the excess expanding coolant of the cooling circuit can flow to the tank T.

After some time after the engine is turned off the coolant temperature drops and the coolant contracts.

The PS piston moves to its maximum displacement position therefore vacuum will be produced in the left chamber. To avoid this condition, the PRV2 pressure maintenance valve puts the left chamber in communication with the environment. If despite opening the pressure holding valve PRV2 the piston PS reaches its maximum displacement position, this means that the cooling process in the DC cooling circuit is not yet complete, therefore the non-return valve FVV described in Figure 2 can probably open, sharing the vacuum also with the coolant tank T. Advantageously, the coolant is balanced until the coolant has reached ambient temperature and the cooling process is complete.

Instead of a double piston cylinder, it is also possible to use a cylinder with a spring loaded piston such that a spring moves the piston towards its minimum displacement while a single chamber equivalent to the left chamber above is used to move the piston to its maximum displacement position. In this case the VV valve is not necessary.

According to the present embodiment, instead of signaling to the driver when the ECU detects air in the system or a leak in the cooling system or a level sensor is installed in the tank and when coolant falls below the predetermined level a signal is provided to the driver warning.

The present invention can be advantageously implemented in a computer program comprising program code means for executing one or more steps of such a method, when such a program is run on a computer. For that reason, the patent will also cover that computer program and the computer readable medium comprising a recorded message such as a computer readable medium comprising the program code means for performing one or more steps of that method when that program is running. on a computer.

Many changes, modifications, variations and other uses and applications of the subject invention will become apparent to those skilled in the art after considering the description and accompanying drawings describing preferred embodiments thereof. All such changes, modifications and variations, other uses and applications which do not depart from the scope of the invention are considered to be covered by the present invention.

It should be understood that all individual features / embodiments can be combined with each other. Furthermore, the features described in the prior art are introduced only to better understand the invention not as a statement of the existence of the prior art. Therefore, the features described in the prior art can also be considered in combination with those mentioned in each embodiment of the detailed description.

Further implementation details will not be described as the person skilled in the art is able to realize the invention starting from the teaching of the above description.

Claims (14)

CLAIMS 1. Cooling system of an internal combustion engine (ICE) comprising a cooling circuit (CC) with - a pump (P) to circulate the coolant, - a radiator (R) suitable for dispersing the heat produced by the internal combustion engine into the environment, - at least a first pipe (P1) to convey the coolant from the internal combustion engine towards the radiator e - at least a second pipe (P2) connecting the radiator to the pump, the system further comprising - a cylinder (C) / piston (P) (CPA) assembly which defines a chamber (CH) suitable for being connected hydraulically to said second pipe (P2) through a third pipe (P3) in communication with said second pipe ( P2), - an actuator (A) connected to said piston to control its displacement in said cylinder by varying said chamber volume, - a pressure sensor (PR) in hydraulic communication with said cooling circuit (CC) e - an electronic control unit (ECU) coupled to said pressure sensor and to said actuator and configured to control said actuator to maintain a pressure measured by said pressure sensor above a predetermined threshold. 2. A system according to claim 1, wherein said control unit is configured to maintain said pressure in a predetermined pressure range. System according to claims 1 or 2, in which the chamber (CH) is equipped with a deflector (B) of elastic material. 4. A system according to claim 3 wherein said deflector is disposed on the inner surface of the chamber facing said piston. System according to any one of the preceding claims further comprising a displacement sensor (DS) for detecting a position of the piston in said cylinder in which said electronic control unit is also coupled to said displacement sensor (DS) and configured so that when the piston reaches a maximum displacement condition corresponding to the minimum chamber volume (CA) and the pressure is still below a predefined threshold, it generates a warning. System according to any one of the preceding claims wherein said electronic control unit is configured to detect an ON / OFF ignition state and an ON / OFF internal combustion engine state. 7. System according to any one of the preceding claims 1 to 6, further comprising a three-way valve (V1) in which a first port of the three-way valve (V1) is in communication with said cooling circuit, in which said cylinder assembly the piston is connected to a second port of said three-way valve (V1) in which the system further comprises a refrigerant tank (T) connected to a third port of said three-way valve (V1); wherein according to a first condition a) the three-way valve connects the cylinder / piston group to said coolant tank and according to a second condition b) the three-way valve connects the cylinder / piston group with the cooling circuit (CC) wherein said control unit (ECU) is configured to also control said three-way valve so that the three-way valve is in said condition b) when the displacement of the piston is adjusted to maintain a pressure measured by said pressure sensor above said predetermined threshold. 8. System according to claim 7, wherein said control unit (ECU) is further configured to carry out a filling of the cooling circuit by passing said three-way valve (V1) in said first condition a) and to move said piston towards its position of minimum displacement by sucking the refrigerant from said refrigerant circuit (T). System according to claims 7 or 8 wherein said control unit is further configured to perform an air detection procedure: - said three-way valve (V1) is commanded to assume said condition b) and the piston (PS) is commanded to move towards its maximum displacement position, while - the pressure sensor (PR) detects the pressure in the cooling circuit (CC) - the ECU is configured to compare a pressure variation with a force exerted by said piston (PS) on the cooling circuit and to evaluate the quantity of air in the cooling circuit, provided that the air is compressible. System according to one of claims 7 to 9, further comprising - a sixth tube (P6) which connects an upper portion of the internal combustion engine (ICE) to an upper portion of said coolant tank (T) in a second controllable valve (V2), normally closed, arranged on said sixth tube ( P6) and / or - a seventh pipe (P7) which connects an upper portion of the radiator (R) to an upper portion of the coolant tank (T) and a third controllable valve (V3), normally closed, arranged on said seventh pipe (P6) wherein said control unit (ECU) is configured to perform a deaeration procedure comprising controlling - said first three-way valve (V1) so that it assumes said first condition a), therefore - the piston to move towards said minimum displacement position, successively - said first three-way valve (V1) so that it passes into said second condition b) e - said second and / or third valve (V2, V3) so that they open while the piston moves towards its maximum displacement, therefore the air is pushed by the engine and / or the radiator towards the tank, subsequently said second and / or third valve (V2, V3) so that they close. System according to any one of the preceding claims 7 to 10 further comprising a pressure source (AS) in which said piston / cylinder assembly is pneumatically operated by means of said pressure source (AS). 12. System according to claim 11 wherein said piston is of the double action type having first and second movable pistons interconnected by a piston rod, the first movable piston defining, on the piston face, a first chamber (LC) and on the opposite face said chamber (CH) i communicating with the cooling circuit (CC) and said second piston defines a second chamber (RC) in which the first and second chambers are separated from each other by a fixed central partition, in which said first chamber (LC) and said second chamber (RC) are suitably connected to said pressure source to control a displacement of the piston inside the cylinder. 13. System according to claim 11 wherein said first chamber (LC) is in operative communication with said source of pressurized air through a first control valve (PV) and wherein when the ignition is off said three-way valve (V ) assumes said second condition b) and said first control valve (PB) is in neutral position while blocking all its doors. Land vehicle comprising an internal combustion engine (ICA), an internal combustion engine cooling system according to any one of the preceding claims 1 to 13.