Patent Description:
In the field of internal combustion engine cooling, in some cases, the cylinder head and the engine block are cooled in a parallel manner, whereas, more often, the cooling water flows into the engine block and then entirely circulates through the cylinder head in order to be then collected in a suitable outlet manifold. Known engines with cooling circuits are disclosed in <CIT> or <CIT>.

A radiator is connected to the cooling circuit in order to cool the water circulated in the internal combustion engine, thus releasing heat into the atmosphere.

A thermostatic valve generally steps in, bypassing the radiator as long as the water does not reach a predetermined temperature.

According to a known improving solution, a valve with a motor-driven rotating shutter is used, which allows for an adjustment of the flow rate of the cooling water, hereinafter referred to as "refrigerant", which flows through the internal combustion engine and other auxiliary elements. Among the auxiliary elements there are, for example, the exchanger for the oil of the engine or for the oil of the gearbox and the heater of the vehicle cabin housing the internal combustion engine.

Said valve comprises a port for each user, for example the cylinder head and the engine block, as well as two mixing ports, a first port being connected to the radiator and a second port being connected to the circulation pump, so as to bypass the radiator.

An opening rotation of the shutter determines an opening in sequence of the apertures of the relative users and the gradual switching between the first port and the second port.

Therefore, the ratio between the flow rate of the refrigerant flowing through the users and the temperature of the mixed water is fixed and depends on the angular position of the rotating shutter.

The basic difference from a traditional thermostatic valve lies in that the operating temperatures of the single users can be handled in a more accurate manner, so that they can operate at higher mean temperatures, in order to reduce frictions inside of the internal combustion engine.

<FIG> of the prior art shows the interaction of the rotating shutter valve of the prior art with the users, the circulation pump, the radiator and the bypass of the radiator.

If not specifically excluded by the detailed description below, the information contained in this part should be considered as an integral part of the detailed description itself.

Said prior art can be improved so as to obtain further benefits. <CIT> and <CIT> show solutions according to the preamble of claim <NUM> and disclose control valves capable of independently controlling the flow of coolant through a cylinder head and cylinder block of a combustion engine. In particular, the control valve of <CIT> includes a rotatable drum that rotates about its longitudinal axis and is actuated by an electric motor coupled to an engine control system, to allow coolant circulation based on a temperature within the engine.

The aim of the invention is to improve the thermal control of an internal combustion engine and of a vehicle including said internal combustion engine.

The idea on which the invention is based is that of using a first valve, preferably with a rotating shutter, to adjust the flow rates of the refrigerant flowing through two or more users and a second valve, separate and distinct from said first valve and preferably with a rotating shutter, to adjust an operating temperature of the refrigerant.

An adjustment of the fluid flow rates evidently affects the temperatures of the cooled component, but, thanks to the invention, an operating temperature of the refrigerant is established independently of the fluid flow rates circuited in the different components cooled by the cooling circuit.

In other words, the temperature of the refrigerant is defined by the second valve, whereas the refrigerant flow rate in each cooled component is defined by the first valve.

Hereinafter, the term "user" indicates a component cooled by the cooling circuit.

Thanks to the invention, the flow rate of the refrigerant circulated through the single users is independent of the temperature of the refrigerant sent to the users themselves.

The first valve and the second valve are controlled by means of respective electric motors, which are independent of one another.

In other words, while the sole rotating shutter valve of the prior art adjusts, at the same time, the refrigerant flow rates and the refrigerant temperature according to predetermined fixed ratios, in this invention these functions are divided between the first and the second valve, thus potentially leading to infinite combinations between flow rates and operating temperature of the refrigerant fluid circulated through the users.

Furthermore, the possibility of adjusting the temperature of the recirculated fluid independently of the recirculated flow rates allows for ideal engine pressurization levels; indeed, keeping the temperature of the fluid high, in order to reach predetermined temperatures within the single cooled components it is possible to circulate greater refrigerant flow rates with a consequent ideal pressurization of the cooled component. The valve assembly comprises the first valve and the second valve and is connected between the outlet of the users and the inlet of the circulation pump, upstream or downstream of said at least one radiator.

Thanks to the invention, the possible cavitation of refrigerant in the ducts inside the users is completely avoided.

The first valve preferably controls, in a sequential manner, at least the flow rates of the refrigerant flowing through at least two different portions of the internal combustion engine, such as for example the cylinder head and the engine block.

Therefore, the portions of the internal combustion engine are inserted in a first circuit including the first valve, the second valve, the radiator, which, depending on the position of the second valve, is at least partially included or completely bypassed, and a circulation pump.

According to another preferred variant of the invention, the cooling circuit comprises two distinct and separate radiators, which are arranged in series relative to one another, and the second valve is connected in parallel to the series of the first and second radiator; this parallel configuration, which is obtained by so doing, is connected immediately downstream of the first valve.

A duct connects the connection point between the outlet of the first radiator and the inlet of the second radiator to a port of the second valve.

The outlet of the second valve is connected to the inlet of the recirculation pump.

Unlike the first variant, this variant allows the water coming from the first valve to be mixed with the water coming from the first radiator or from the series of the first and second radiator. This allows for a quick cooling of the refrigerant under maximum thermal load conditions.

Indeed, the series of the first and second radiator corresponds to the nominal exchange surface needed for a predetermined application. The fact that the radiator is divided into two portions allows for a greater efficiency of the first one, namely the one directly connected to the first valve, in the exchange of heat with the atmosphere, whereas the second radiator, which is less efficient for it has a lower temperature, is used only occasionally and to face greater loads, thus offering further advantages.

According to a preferred variant of the invention, the second radiator can be steadily used in an independent circuit to cool the air compressed by the supercharging compressor of the internal combustion engine and, when needed, it is introduced in the cooling circuit of the internal combustion engine to face possible load and heat peaks.

According to claim <NUM>, the second valve is connected not only to the radiator or radiator battery and to the circulation pump, but also to a heat recuperator.

Heat recuperators are heat exchanger arranged on the exhaust pipe as last component and are used in the first engine cold start phases in order to recover the heat content of the exhaust gases to heat the refrigerant. In this variant of the invention, as well, the second valve has the task of defining the operating temperature of the refrigerant, whereas the first valve adjusts the flow rates.

Thanks to the invention, the temperature of the users can be controlled independently of the flow rate of the refrigerant flowing through the users themselves, thus ensuring a uniform distribution of the heat, which allows the engine to operate at higher temperatures with a great accuracy.

The fact of operating at higher temperatures allows for a reduction in the viscosity of the oil and, hence, in the frictions of the mechanical components, thus increasing the efficiency thereof without the risk of thermal shocks of some of the users.

Further aims and advantages of the invention will be best understood upon perusal of the following detailed description of an embodiment thereof (and of relative variants) with reference to the accompanying drawings merely showing non-limiting examples, wherein:.

In the figures, the same numbers and the same reference letters indicate the same elements or components.

For the purposes of the invention, the term "second" component does not imply the presence of a "first" component. As a matter of fact, these terms are only used as labels to improve clarity and should not be interpreted in a limiting manner.

The elements and features contained in the different preferred embodiments, drawings included, can be combined with one another, without for this reason going beyond the scope of protection of this patent application, as described hereinafter.

An internal combustion engine E comprises a cylinder head CH, which is coupled to an engine block CB, where at least one cylinder is obtained, in which a relative piston slides.

The drive shaft (not shown) is connected to a transmission, which preferably comprises a gearbox GB.

The invention can also be dedicated to a fixed installation, in which the internal combustion engine E drives an electric generator and, therefore, the gearbox GB could be absent.

According to the invention, the cooling circuit CO of the internal combustion engine includes at least:.

Like the prior art, the valve assembly defines the fraction of refrigerant sent to the users of the cooling circuit without any cooling of the refrigerant and a remaining part circulated through the radiator RD and subsequently sent to the users, thus obtaining a mixing of hot refrigerant flowing out of the users and cold refrigerant flowing out of the radiator RD.

Unlike the prior art, though, the valve assembly does not include one single valve, but two valves <NUM>, <NUM>:.

wherein said second valve is arranged to define an operating temperature of the refrigerant and said first valve is arranged to selectively adjust the flow rates of the refrigerant circulating through said at least two inlet ports P1, P2, P3,.

Therefore, the second valve <NUM> is arranged to adjust a mixing of refrigerant flowing out of the plurality of users with refrigerant flowing out of said at least one radiator RD.

It is evident that the second valve can completely bypass said at least one radiator, so that the entire recirculated refrigerant is the same as the refrigerant flowing out of the plurality of users.

In the same way, the users involved in the mixing carried out by the second valve <NUM> depend on the position of the first valve <NUM>, since the latter could potentially completely stop the circulation of refrigerant through the plurality of users.

<FIG>/<FIG> show variants applying the invention.

According to the diagram of <FIG> (not part of the invention), there is one single engine cooling radiator RD, which is arranged downstream of the second valve <NUM>, so that the following sequence is obtained:
first valve <NUM>, second valve <NUM>, radiator RD, pump CP, engine E.

According to the diagram of <FIG> and <FIG>, the first radiator RD1 is operatively interposed between the first valve <NUM> and the second valve <NUM>, so that the following sequence is obtained:
first valve <NUM>, first radiator RD1, second valve <NUM>, second radiator RD2, pump CP, engine E. This allows the radiators RD1 and RD2 to be arranged in series.

<FIG> differs from <FIG> only in that the second radiator is connected to a cooling circuit for the air compressed by the compressor, so that it can be introduced in the cooling circuit of the engine only when it is necessary.

According to <FIG>, the second radiator is connected, independently of the operating conditions of the second valve, to a heat exchanger WCAC designed to work as an intercooler. An electric pump ePump allows the refrigerant to circulate through the circuit including the second radiator RD2, the electric pump ePump and the exchanger WCAC.

When needed, the second valve allows the second radiator to operate in series with the first radiator, thus evidently worsening the efficiency in the cooling of the air compressed by the supercharging compressor, but causing an immediate benefit for the internal combustion engine E when it needs to face a sudden load or heat peak.

As far as the sizing is concerned, given a target heat exchange surface, it can be obtained by adding the first and the second radiator.

This implies that, if the second radiator is generally involved in the circuit of the WCAC, the sizing thereof does not need to depend on the needs of the WCAC, but on the nominal needs of the internal combustion engine, taking into account the exchange surface of the first radiator RD1.

Anyway, it is evident that the electric pump ePump can be properly controlled taking into account the dimensions of the second radiator RD2. In other words, if the latter is oversized because of the task linked to the WCAC, it means that the flow rate of the refrigerant pumped by the WCAC can proportionally be reduced, taking into account that the risks of cavitation are modest or non-existent in that circuit.

The cylinder head of the internal combustion engine preferably comprises an opening, which is directly connected to the inlet <NUM> of the second valve <NUM>. As a matter of fact, the first valve is at least partially bypassed by means of this bypass connection CB1 for the first valve. Said opening allows the cylinder head to always have a minimum circulation of refrigerant, preventing it from boiling in contact with some inner parts of the cylinder head that can reach high temperatures. For example, when the exhaust manifold is inside the cylinder head, temperatures can reach <NUM> very quickly.

In any case, this arrangement avoids thermal fatigue or cavitation phenomena due to a local boiling on the flame plate or in the bridges between the valves, in particular between the two exhaust valves of an engine provided with <NUM> valves per cylinder.

If the internal combustion engine E is also provided with a turbocharger unit TB cooled by means of the same refrigerant, said unit is preferably connected to the bypass connection CB1 for the first valve, so as to have a predetermined and constant circulation of refrigerant.

When the internal combustion engine is designed for a vehicle application, downstream of the turbocharger there is the heater CBH of the cabin of the vehicle VHE, which is useful for a relative HVAC, namely a conditioning device for the cabin CAB of the vehicle, HVAC meaning "Heating, Ventilation and Air Conditioning", which is well known to a person skilled in the art.

The first valve <NUM> and/or the second valve <NUM> preferably are valves with a rotating shutter, in which an aperture respectively corresponds to each inlet and outlet port, the opening of the aperture depending on an angular position of a shutter within a respective valve body.

The first valve can comprise an axial through path, which is not adjustable, so that the bypass of the first valve can be obtained by following said path, which leads to the outlet PU, to which the different ports P1, P2, etc. are connected.

According to a preferred variant of the invention, which can be combined with any one of the variants described above, the engine comprises an EGR circuit, namely a circuit used to recirculate exhaust gases through the engine itself in order to reduce Nox generated during the combustion taking place in the internal combustion engine.

Hereinafter, for greater simplicity, the internal combustion engine E will simply be referred to as "engine". The exhaust gas recirculation circuit can comprise a first heat exchanger EGRC, which defines a further user of the cooling circuit, so that the first valve <NUM> comprises an inlet port P4 (see <FIG>), which is operatively connected to the outlet of the first heat exchanger.

When the engine is associated with a gearbox GB, the latter generally has an oil lubrication and cooling circuit with a relative third heat exchanger, which, for greater simplicity, is indicated with the same symbol GB as the entire gearbox. The outlet of said third exchanger is connected to an inlet port P3 of the first valve <NUM>.

Furthermore, the internal combustion engine E itself comprises an oil lubrication circuit and a relative second heat exchanger OIL Exch, which is cooled by means of the refrigerant of the circuit according to the invention. Therefore, the first valve <NUM> comprises an inlet port P5, which is operatively connected to the outlet of the second heat exchanger OIL Exch.

Different users, besides the engine itself, have been listed, each of said users being optional; furthermore, further users can be provided and be connected to the first valve <NUM>, preferably by means of relative ports.

According to a preferred variant of the invention, which can be combined with any one of the preceding variants, the internal combustion engine E comprises an exhaust pipe EP, on which an exhaust gas treatment device ATS is arranged.

Downstream of the ATS, according to the exhaust gas circulation direction, on the exhaust pipe EP there is a heat recuperator EX. It consists of a gas/liquid heat exchanger, in which the liquid coincides with the refrigerant, whereas the gas coincides with the exhaust gas produced by the internal combustion engine.

Said heat recuperator allows the heat of the exhaust gas to be recovered before being released into the atmosphere. It helps adjust the temperature of the refrigerant.

An inlet of the heat recuperator is connected in a point of the cooling circuit between the outlet of the valve <NUM> and the inlet of the valve <NUM>, whereas the outlet of the exchanger feeds a dedicated inlet aperture of the valve <NUM> and, through the latter, the engine E, more precisely the users defined by engine itself, among which there are the cylinder head, the engine block and, optionally, the EGR cooler EGR C, the engine oil cooler OIL Exch. and the cooler of the oil of the gearbox GB, which, despite not being part of the engine, generally receives the refrigerant from the engine itself.

A valve <NUM> can be placed in the exhaust gas circuit, thus allowing the gases to completely bypass the heat recuperator Ex.

It is optional, since the second valve <NUM> is decisive in allowing or not allowing the heat recuperator to be inserted in the cooling circuit, but it is useful to prevent the refrigerant fluid from boiling inside said exchanger under exhaust gas high temperature conditions, while the heat recuperator is excluded from the circulation of refrigerant by the second valve.

Owing to the above, the cooling circuit, despite having to fulfil a limited engine cooling function under cold start conditions, is activated in order to accumulate heat and allow the refrigerant, first, and the users, as a consequence, to reach the best thermal operating conditions.

It should also be clear that the drawings do not show the portion of the cooling circuit that splits the refrigerant pumped by the pump CP among the different users: these details, which are usually incorporated in the channels obtained, through casting, in the crankcase of the engine, are known to a person skilled in the art.

The cooling circuit can get into the engine through one single inlet or can get into the different users from the outside.

According to a preferred variant of the invention, the refrigerant flows into the engine E through one single opening made in the engine block, which allows access to the liner of the engine block and, from the liner, the refrigerant flows into the cylinder head, cools the exhaust manifold integrated in the cylinder head and flows out of the engine through a first outlet opening CH1, which is connected to the first port P1, a second outlet port CH2, which is connected to the bypass connection CB1 for the first valve, and a third opening, which opens up in the liner of the engine block.

A preferred control method to control the valves <NUM> and <NUM> in relation to the operating conditions of the engine is described below. Said method, in the example discussed herein, entails the presence of different users besides the internal combustion engine and entails the presence of one user. It is evident that one or more users can be absent and the presence of the heat recuperator is completely optional.

According to the method, the first valve is controlled according to at least one of the procedures listed below as the refrigerant flow rates increase starting from a condition of complete closing of the ports of the first valve:.

State A represents the fact that the bypass duct CB1 bypasses the first valve <NUM>, thus allowing the refrigerant to circulate through the cylinder head of the engine and through the jacket of the turbocharger, regardless of the operating condition of the first valve <NUM>.

The first valve preferably has an outer cylindrical jacket and an inner shutter, which is also cylindrical, and the bypass CB1 is obtained in the first valve <NUM> by means of a path that is axial relative to the first valve.

The procedures listed above depend on the users available, some transitions and some operating conditions can be absent because the relative users are absent.

Furthermore, the procedures include both almost-static conditions and transitions and it has to be clear that, by adjusting the refrigerant flow rate with continuity through the different users, the corresponding operating conditions of the first valve <NUM> define a continuous sequence of states, even if the apertures made in the rotating shutter can be shaped so as to open and/or close in a quicker or less quick manner.

The first operating condition of the valve is identified with condition B) and not A), since there is an implicit condition of circulation of the refrigerant through the connection duct CB1, regardless of the operating condition of the first valve.

As far as the control of the second valve is concerned, it is controlled as the temperature of the refrigerant increases starting from a cold start by means of the following procedures:.

This last transition is particularly useful when, at the end of a high load phase, the load drastically decreases and, therefore, a relatively high temperature of the refrigerant needs to be restored.

Below you can find a description of a joined control of the first and second valves starting from a cold start condition up to a steady running condition:.

Claim 1:
An internal combustion engine (E) comprising an engine block (CB), in which at least a piston is coupled in a respective cylinder, and a cylinder head (CH) coupled with said engine block, a cooling circuit (CO) of the internal combustion engine including
• at least a first radiator (RD1),
• a circulation pump (CP) for circulating a refrigerant through a plurality of users, among which said cylinder head and said engine block are included, and
• a valve assembly (V) arranged to control a fraction which is part of the refrigerant circulated through said first radiator (RD1),
the valve assembly (V) consisting of
- a first valve (<NUM>) having at least two inlet ports (P1, P2, P3 ...) wherein a first inlet port (P1) is operatively connected with said cylinder head (CH) and a second inlet port (P2) is connected with said engine block (CB) and an outlet port (PU),
- a second valve (<NUM>) having at least one first inlet port (<NUM>) operatively connected with said outlet port (PU) of the first valve (<NUM>) and at least two further ports (<NUM> - <NUM>), of which a first one (<NUM>) is directly connected with said circulation pump (CP) and a second one (<NUM>, <NUM>) is indirectly connected with said circulation pump (CP) through said first radiator (RD1);
wherein said second valve (<NUM>) is arranged to define an operating temperature of the refrigerant and said first valve (<NUM>) is arranged to selectively adjust the flow rates of refrigerant circulating through said at least two inlet ports (P1, P2, P3, ...);
wherein the internal combustion engine (E) further comprises an exhaust pipe (EP) and a heat exchanger (Ex. Exch) arranged on said exhaust pipe for recovering heat from exhaust gases produced by the internal combustion engine before being released into the environment;
characterized in that said heat exchanger (Ex. Exch) is operatively connected
• with said cooling circuit in a point arranged immediately downstream of said first valve (<NUM>), and
• with a second inlet port (<NUM>) of said second valve (<NUM>),
wherein said second valve (<NUM>) is arranged to define a temperature of the refrigerant by adjusting a mixing between refrigerant circulated in said internal combustion engine (E) with refrigerant circulated through said heat exchanger (EX. Exch) or refrigerant circulated through said internal combustion engine with refrigerant circulated through said first radiator (RD1).