ES2752698T3 - Cooling system of an internal combustion engine - Google Patents

Abstract

An internal combustion engine cooling (ICE) system comprising a cooling circuit (CC) with - a pump (P) to circulate the coolant, - a radiator (R) suitable for dispersing the heat produced by the engine internal combustion in the environment, - at least a first pipe (P1) to transport coolant from the internal combustion engine to the radiator and - at least a second pipe (P2) connecting the radiator with the pump, The system also includes - a cylinder (C) / piston (P) assembly (CPA) defining a chamber (CH) suitable for hydraulically connecting with said second pipe (P2) through a third pipe (P3) communicating with said second pipe ( P2), - an actuator (A) connected to said piston to control its movement in said cylinder, varying said chamber volume, - a pressure sensor (PR) in hydraulic communication with said cooling circuit (CC) and - a unit (ECU ) electronic control coupled with said pressure sensor and with said actuator and configured to control said actuator in order to maintain a pressure measured by said pressure sensor above a predetermined threshold; the system being characterized in that it comprises a three-way valve (V1), in which a first port of the three-way valve (V1) communicates with said cooling circuit, in which said cylinder / piston assembly is connected to a second port of said three-way valve (V1), and 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 assembly with said refrigerant tank, and according to a second condition b) the three-way valve connects the cylinder / piston assembly with the cooling circuit (CC) and in which 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 piston displacement is adjusted to maintain a pressure measured by said pressure sensor above said predetermined threshold.

Description

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

Conventional pressurization systems focus on pressurization on the air side of the expansion tank. It is an indirect pressurization. The coolant pressure level will increase with the passive pressure increasing in the expansion air tank, depending on the coolant temperature and the coolant recirculation induced by the coolant pump.

Indirect pressurization is slow and uncontrollable. It would be useful if pressurization were faster and more controllable than with indirect (conventional) pressurization.

Document FR2923261 discloses an expansion tank for the cooling circuit of the vehicle's internal combustion engine, having a container including a chamber provided with parts containing liquid and air, respectively, and a pressurization unit according to the preamble. of claim 1.

Summary of the Invention

Therefore, the main objective of the present invention is to provide a cooling circuit, which overcomes the above problems / drawbacks through direct pressurization of the cooling circuit. A cooling system according to the invention is defined in appended claim 1.

The benefits of direct pressurization are that it is independent of the activation of the coolant circulation pump and of the heat produced by the internal combustion engine, so that good pressurization can be achieved also when starting the engine cold.

The main idea of the present invention is to replace the expansion tank with an auxiliary pressurization assembly comprising a cylinder / piston, where the cylinder communicates with the cooling circuit. Thus, the movement of the piston in its cylinder allows direct pressurization of the circuit reached not through the air supply.

An actuator is coupled with the piston in order to control its displacement. Furthermore, an electronic control unit is configured to control said actuator. Preferably, said electronic control unit coincides with the delegate to control the internal control unit.

In accordance with the preferred embodiment of the invention, the pressure in the cooling circuit is controlled by the cylinder / assembly, therefore, the piston displacement 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 draw refrigerant from a tank to fill the cooling circuit, both to compensate for the loss of refrigerant and to vary the amount of refrigerant in the cooling circuit according to its operating conditions.

In accordance with a preferred embodiment of the invention, the piston is provided with an elastic damper to minimize pressure peaks in the cooling circuit.

In accordance with the invention, the auxiliary pressurization assembly comprises a refrigerant tank connected to the cooling circuit and to the above cylinder / piston through a three-way valve, where a first port of the three-way valve is directly connected to the cooling circuit, preferably in the suction line, a second port is directly connected to the cylinder / piston assembly and a third port is directly connected to said coolant tank. Preferably, said electronic control unit is configured to also control said three-way valve to develop various procedures to control the state of the cooling circuit and the auxiliary system. Another object of the invention is the method for operating the pressurization system in order to discharge, fill and pressurize the cooling circuit according to the second embodiment disclosed in the following detailed description. These and other objects are achieved by the appended claims, which describe preferred embodiments of the invention, which form an integral part of the present disclosure.

Brief description of the drawings

The invention will become fully clear from the following detailed description, given by way of merely illustrative and non-limiting example, which will be read with reference to the attached drawing figures, in which:

Fig. 1 schematically shows an example that is not part of the present invention.

Fig. 2 schematically shows an embodiment of the refrigeration system according to the present invention.

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

The same reference numbers and letters in the figures designate the same parts or functionally equivalent parts.

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 motor, a radiator R suitable for dispersing heat in the environment and eventually a suitable fan (not shown) to increase the convection effects of said heat dispersion.

At least one pipe P1 carries the hot coolant from the internal combustion engine to a higher part of the radiator R, and at least other pipes, called the second pipe P2, connect a lower part of the radiator with the pump P. Usually, the pump it is arranged directly on the combustion engine block, therefore no further pipes are disclosed, however another pipe / step connects the pump to the internal combustion engine.

Figure 1 discloses an example that is not part of the present invention.

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

The PS piston is movably coupled with its cylinder C. The CH chamber formed between the piston and the cylinder is in hydraulic communication with the cooling DC circuit through the second pipe P3. Said cylinder chamber is also referred to below as the refrigerant chamber.

An actuator A commands the displacement of the piston in the cylinder, therefore, when the cooling circuit is sealed, the displacement of the piston varies the pressure within the cooling circuit itself.

The actuator can be an electric drive or a pneumatic actuator. The opposite face of the piston PS facing the CH chamber of the refrigerant can be subjected to a pneumatic action in order to order its displacement in its cylinder. In accordance with a preferred embodiment of the invention, a chamber surface facing the piston is provided with a baffle B to avoid pressure peaks.

In accordance with a preferred embodiment of the invention, a pressure PS sensor, such as a piezoelectric sensor, is also associated with the cooling circuit, for example, it can be coupled with the cylinder refrigerant chamber CH or along the third P3 pipe connected to the CPA assembly with pipe 2.

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

When the piston reaches a second position corresponding to the smallest volume of the CH refrigerant chamber and the pressure is still below that predefined range, a warning is sent to the vehicle's instrument panel to indicate to the driver that the circuit lacks coolant / cooler.

A person skilled in the art can implement a contact sensor or any other suitable displacement DS sensor to detect the position of the piston. It could be coupled with the piston rod or it could be a Hall known per se.

According to a preferred embodiment of the invention, when the ignition changes from ON to OFF, the piston moves in a second position, corresponding to the highest volume of the CH chamber.

This operation does not ensure injury to the operator who opens the cooling circuit and allows proper refueling of the circuit.

Figure 1 discloses an electronic control ECU unit that controls pressure and controls actuator A that matches the Engine Control Unit, i.e. the electronic control unit that controls the internal combustion ICE engine. However, a separate electronic control unit can be implemented. For example, in accordance with the present invention, equipment can be devised to close conventional cooling circuits so that it is sufficient to hydraulically connect cylinder C with the cooling circuit and control unit to the vehicle battery and to energized power cord when ignition is ON.

Figure 2 discloses an embodiment of the present invention.

As for the previous example, ICE represents an internal combustion engine and R a radiator to dissipate the heat in the environment produced by said internal combustion engine. The first P1 pipe connects a high portion of the radiator to the ICE.

The second pipe P2, instead, connects a lower portion of the radiator with a pump P that draws coolant from the radiator to cool the ICE.

The third pipeline P3 is connected, at one end, with the second pipeline P2 in a T-connection, and at a second end, with a first port of a three-way valve V1.

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

According to condition a) of the three-way valve, the fourth line P4 and the fifth line P5 communicate with each other, while according to condition b) of the three-way valve, the third line P3 and the fourth P4 pipeline communicate with each other

Preferably, a first FVV check valve bypasses the three-way valve V1 that connects the pipes P4 and P5. If the engine is off, the piston can draw fresh coolant from the tank without changing valve V1 to that condition a). This indicates that instead of a three-way valve, it is possible to implement a simple two-way valve in line P4, by installing a check valve in line P5 and inserting a T-connection instead of the three-way valve. .

In addition, a sixth P6 pipeline connects a higher portion of the ICE with a higher portion of the tank in order to allow air removal from the ICE, and a seventh P7 pipeline connects a higher portion of the R radiator with said higher portion. tank T to allow removal of air from the radiator.

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

Preferably, the release valve SPRV prevents said third valve V3 by allowing the radiator to discharge medium into tank T in case of overpressure in the radiator.

As in the previous example, when the piston is at the minimum displacement, the CH refrigerant chamber is the main size and vice versa, when the piston is at the maximum displacement, the CH refrigerant chamber is the minimum size. According to this embodiment, the ECU is programmed to carry out at least one of the following operations:

When the engine is started, the three-way valve changes to said condition b) and the piston regulates the pressure in said cooling circuit above the previous threshold or within the previous interval. Then, the three-way valve is switched in said condition a) as long as said detected pressure is above said threshold or within said pressure range.

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

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

When the amount of air exceeds a predetermined threshold, an air discharge / removal procedure is performed.

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

According to the discharge procedure, valve V1 assumes condition a), whereby the piston moves towards its minimum displacement. This implies that aspirating the refrigerant from tank T. Then, V1 changes to condition b) and valve V2 and / or V3 opens, while the piston moves towards its maximum displacement, therefore, the air is pushed from the engine and / or radiator to tank. Valves V2 and V3 are then closed and kept closed.

After the unloading procedure, which can be executed for one or both branches, in parallel or in succession, the air detection procedure is carried out again and, finally, the unloading 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 starting the engine, the piston is controlled according to closed circuit control to maintain a target pressure in the cooling circuit while the engine is on. After the pressure stabilization in the cooling circuit, valve 1 could be switched in said condition a), disconnecting the piston from the cooling circuit.

When the ignition switch rotates to the "ON" position and the engine is not running, the ECU performs a reset of the piston: the ECU detects the position of the piston and, if it is outside of a predetermined range of positions, preferably Centrally arranged with respect to the entire piston displacement, valve V1 is switched in condition a) and the piston moves to reach said predetermined interval.

This procedure allows the piston to be kept in an intermediate position throughout its entire movement, so that it is controlled to compensate positively or negatively for the pressure variations detected in the cooling DC circuit.

In order to avoid the opposite situation where the piston is close to its minimum displacement condition, the displacement towards the minimum displacement condition during the suction of refrigerant from the tank can be suitably limited.

Regardless, the "centering" operation of the piston in the above range of positions can be obtained by opening one or both of the above V2 / V3 valves as disclosed in the above discharge procedure and moving the piston towards said intermediate position.

Figure 3 shows an example of a piston actuated by means of the pneumatic circuit of the vehicle. Heavy vehicles are generally provided with a pneumatic circuit to control braking and / or vehicle suspensions. Therefore, Figure 3 shows a preferred embodiment of the invention that can be combined with the one described above according to the embodiment of Figure 2.

The disclosed piston is pneumatically controlled and is of the double acting type. In particular, it has a first or refrigerant CH chamber that communicates with the cooling circuit as in Figures 1 or 2 and a left LC chamber and a right RC chamber separated from the left chamber through a fixed central partition.

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

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

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

The ECU is also configured to control the PV and VV valves on the basis of pressure values measured by the PR sensor alone or also on the basis of Psens and Vsens measurements, firstly to pressurize the velocity DC circuit when the Engine is running, or to perform the above air detection and air discharge / removal procedures or such a reset of the piston.

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

The VV valve has two positions (configurations) and is suitable, in a first position (from the top), to connect the right chamber with the air pressure AS to generate the pressure in the right RC chamber with the result to depressurize the left LC chamber and the cylinder or CH refrigerant chamber or, according to a second position (neutral), to connect the right chamber with the "am" environment (discharge).

The PV valve has three positions. The first position (from above) connects the left LC chamber to the environment (discharge) and the pressure source is sealed; the second position (neutral) interrupts all ports, therefore the left chamber and the pressure source are sealed; the third position communicates the left chamber with the pressure source AS to pressurize the left LC chamber and thus the cylinder CH chamber.

Figure 3 is made in accordance with the standard convention on pneumatic drawings, therefore it is per se 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, disclosed in figure 2, assumes said condition b), thus communicating the refrigerant chamber CH of the pressure cylinder with the cooling DC circuit, and the air pressure valve PV is in the neutral (second) position while the VV valve is also in its neutral (second) position.

Pressure in the left chamber, also called "pressure side chamber", can only be relieved through a pressure relief valve PRV1 that communicates with the left chamber, while the pressure in the right RC chamber is reduces to atmospheric pressure.

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

The size of the water tank T is preferably designed and filled with refrigerant so that any excess excess refrigerant in the cooling circuit can flow into tank T.

After a time since the engine is turned off, the coolant temperature drops and the coolant contracts.

The PS piston moves towards its maximum displacement position, therefore vacuum would be produced in the left chamber. In order to avoid such a condition, the PRV2 pressure check valve communicates the left chamber with the environment. If, despite the opening of the pressure check valve PRV2, the piston PS reaches its maximum displacement position, this indicates that the cooling process in the cooling DC circuit has not yet been completed, therefore the FVV check valve disclosed in figure 2 can possibly be opened by sharing the vacuum also with the refrigerant tank T. Advantageously, the cooling liquid is equilibrated until the cooling liquid has reached room temperature and the cooling process is complete.

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

According to the present embodiment, instead of sending a warning to the driver when the ECU detects air in the system or a leak in the cooling system, a level sensor is installed in the tank and when the coolant falls below a level By default a warning is given to the driver.

This invention may be advantageously implemented in a computer program comprising program code means for performing one or more steps of said method, when said program is executed on a computer.

Many changes, modifications, variations, and other uses and applications of the present invention as defined in the appended claims will be apparent to those skilled in the art upon consideration of the specification and the accompanying drawings describing preferred embodiments thereof. All changes, modifications, variations and other uses and applications that do not depart from the scope of the invention as defined in the appended claims are considered covered by this invention.

The features disclosed in the background of the prior art are introduced only to better understand the invention and not as a statement about the existence of the known prior art. Therefore, also the features described in the background of the prior art can be considered in combination with those mentioned in each embodiment of the detailed description.

No further implementation details will be disclosed, since the person skilled in the art can carry out the invention from the teaching of the above description.

Claims (13)

1. Cooling system of an internal combustion engine (ICE) comprising a cooling circuit (DC) with - a pump (P) to circulate the refrigerant, - a radiator (R) suitable for dispersing the heat produced by the internal combustion engine in the environment, - at least a first pipe (P1) to transport coolant from the internal combustion engine to the radiator and - at least a second pipe (P2) connecting the radiator with the pump, The system also includes - a cylinder (C) / piston (P) assembly (CPA) defining a chamber (CH) suitable for hydraulically connecting with said second pipe (P2) through a third pipe (P3) communicating with said second pipe (P2), - an actuator (A) connected to said piston to control its displacement in said cylinder, varying said chamber volume, - a pressure sensor (PR) in hydraulic communication with said cooling circuit (CC) and - an electronic control unit (ECU) coupled with said pressure sensor and with said actuator and configured to control said actuator in order to maintain a pressure measured by said pressure sensor above a predetermined threshold; the system being characterized in that it comprises a three-way valve (V1), in which a first port of the three-way valve (V1) communicates with said cooling circuit, in which said cylinder / piston assembly is connected to a second port of said three-way valve (V1), and 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 assembly with said refrigerant tank, and according to a second condition b) the three-way valve connects the cylinder / piston assembly with the cooling circuit (CC) and in which 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 piston displacement is adjusted to maintain a pressure measured by said pressure sensor above said predetermined threshold. 2. System according to claim 1, wherein said control unit is configured to maintain said pressure within a predetermined pressure range. 3. System according to claims 1 or 2, in which the chamber (CH) is provided with a deflector (B) of elastic material. 4. System according to claim 3, wherein said baffle is arranged on an internal surface of the chamber in front of said piston. System according to any of the preceding claims, further comprising a displacement sensor (DS) for detecting a position of the piston in said cylinder and in which said electronic control unit is also coupled with said sensor (DS) of displacement and configured so that when the piston reaches a maximum displacement condition corresponding to the smallest chamber volume (CH) and the pressure is still below that predefined threshold, it then generates a warning. System according to any of the preceding claims, wherein said electronic control unit is configured to detect an ignition ON / OFF state and an ON / OFF state of the internal combustion engine. 7. System according to claim 1, wherein said control unit (ECU) is further configured to carry out a filling of the cooling circuit by changing said three-way valve (V1) in said first condition a) and moving said piston towards its minimum displacement position sucking refrigerant from said refrigerant tank (T). 8. System according to claims 1 or 7, wherein said control unit is further configured to carry out an air detection procedure: - said three-way valve (V1) is ordered to assume said condition b) and the piston (PS) is ordered to move towards its maximum displacement position, while - the pressure sensor (PR) detects the pressure in the cooling circuit (CC) and - the ECU is configured to compare a pressure variation with a force printed by said piston (PS) with the cooling circuit and evaluate the amount of air in the cooling circuit, as long as the air is compressible. 9. System according to one of claims 1 to 8, further comprising - a sixth pipeline (P6) connecting a higher portion of the internal combustion engine (ICE) with a higher portion of said refrigerant tank (T) and a second, normally closed, controllable valve (V2) arranged in said sixth pipe (P6) and / or - a seventh pipe (P7) connecting a higher portion of the radiator (R) with a higher portion of the coolant tank (T) and a third, normally closed, controllable valve (V3) arranged in said seventh (P7) pipe and wherein said control unit (ECU) is configured to carry out an air removal procedure comprising controlling - said first three-way valve (V1) assumes said first condition a), therefore - the piston moves to its minimum displacement position, then - said first three-way valve (V1) for changing to said second condition b) and - said second and / or third valves (V2, V3) open, while the piston moves towards its maximum displacement, therefore, the air is pushed from the engine and / or the radiator to the tank, then - said second and / or third valves (V2, V3) are closed. 10. System according to any of the preceding claims 1 to 9, further comprising a pressure source (AS) and wherein said piston / cylinder assembly is pneumatically actuated by means of said pressure source (AS). 11. System according to claim 10, wherein said piston is of the double-acting 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 side facing said chamber (CH) that communicates 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 to through a central fixed partition, in which said first chamber (LC) and second chamber (RC) are suitably connected with said pressure source to control a displacement of the piston inside the cylinder. 12. System according to claim 10, wherein said first chamber (LC) communicates operatively 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 (PV) is in the neutral position by interrupting all ports thereof. 13. Land vehicle comprising an internal combustion engine (ICE), and an internal combustion engine cooling system according to any of the preceding claims 1 to 12.