IT201800009735A1 - Hybrid engine perfected. - Google Patents

Description

IMPROVED HYBRID ENGINE

The present invention relates to an improved hybrid engine.

More specifically, the invention concerns a hybrid engine intended, preferably, for traction of vehicles.

In the automotive sector, fuel-powered engines or internal combustion engines, also referred to briefly with the acronym "MCI", or sometimes "hybrid" systems, are widely used to provide work to vehicle wheels. , in which an internal combustion engine and an electric-powered engine transmit work to the vehicle's wheels.

Internal combustion engines exploit the pressure generated by the combustion of a mixture formed by a fuel and an oxidizer to move a moving part, generally a piston sliding inside a cylinder.

Among internal combustion engines, engines that follow an Otto or Diesel thermodynamic cycle are particularly popular.

Taking now into consideration the Otto cycle engines, this has a higher thermodynamic efficiency than a diesel cycle engine with the same compression ratio which, as known, expresses the ratio between the volume of the cylinder at the lower and upper dead center. , respectively indicated with "PMI" and "PMS" in Figure 2.

The pressure-volume diagram of Figure 1A shows the thermodynamic transformations of an Otto cycle, while Figure 1B shows the configurations of the piston-cylinder system in the various phases of the Otto cycle.

In particular, the Otto cycle is divided into the following phases: intake of the mixture of fuel and comburent into the cylinder (phase 1-2), compression of the intake mixture (phase 2-3), ignition ignition (phase 3-4), expansion of the mixture (phase 4-5-2) and discharge of the exhausted mixture (phase 2-1).

However, these motors offer low thermodynamic efficiency, i.e. a low ratio between the work obtained by the motor and the amount of energy used to obtain it.

Taking for example an engine running with an Otto cycle, to improve thermodynamic efficiency it would be necessary to increase the compression ratio, but this is not possible.

One of the reasons that prevents this improvement is given by the fact that for high values of the compression ratio, the mixture composed of air and petrol "detonates", giving rise to damage to the parts of the engine and not allowing optimal combustion, as for high values of the compression ratio, the pressure and therefore the end-of-compression temperature exceed the self-ignition conditions (see point 3 in the diagram of Figure 1A).

Another limit to the achievable efficiency values is linked to the fact that the compression and expansion phases generally take place in the same cylinder, in which the piston has the same stroke both in the compression phase and in the expansion phase; due to this design limitation, when the piston reaches its lowest point in the expansion phase, the fuel and comburent mixture contains a residual energy that cannot be actively exploited (see step 5-2 in figure 1A).

To overcome the limit indicated above, separate cycle internal combustion engines have been developed, such as the Scuderi engine (see figure 3).

In particular, the Scuderi engine works with an Otto cycle divided into two parts that take place inside two separate cylinders, in which a respective piston moves.

In this case, the compression is in fact carried out inside a cylinder called "cold", from which the compressed fluid is transferred to a second cylinder called "hot", where a spark plug is provided to trigger combustion and the following expansion of the fluid.

The two pistons are connected to the same crankshaft, so the piston in the "hot" cylinder transfers part of its work to that of the "cold" cylinder, to compress the sucked fluid.

One of the advantages of this type of engine is the possibility of optimizing the expansion and compression stroke for the individual pistons, in order to ensure maximum efficiency, in particular by trying to fully exploit the expansion stroke and minimize the 5-2 phase. shown in Figure 1A.

The Scuderi engine, however, has a number of disadvantages, such as the conspicuous presence of vibrations of considerable magnitude on the crankshaft.

The possibility of optimizing the stroke of the expansion and compression pistons is also limited by the construction architecture of the Scuderi engine, which prevents separate intervention on the piston-cylinder systems relating to the compression and expansion phases.

One of the factors that has made internal combustion engines successful on traction vehicles is that they can use a fluid with a high energy density, such as gasoline, which is easily transportable.

However, traditional internal combustion engines are also characterized by the production of substances that are harmful to the environment and to humans.

As the combustion temperature increases, there is in fact a corresponding increase in the quantities of CO and NOx produced and then released into the atmosphere.

From this emerges, therefore, the need to find ways to improve the efficiency and quality of combustion.

To reduce the pollutants produced by the vehicle, it is customary to combine the internal combustion engine with a second zero-emission engine, such as an electric motor powered by batteries.

Typically, systems of this type, so-called "hybrid", are equipped with devices for selecting the engine to be used preferably and provide that the internal combustion engine and the electric motor are connected to the same transmission shaft.

This type of system generally guarantees improvements in terms of emissions of pollutants; however, it is characterized by a certain engineering complexity, which negatively affects both the manufacturing costs and the weight of the vehicle.

In the light of the above, it is therefore an object of the present invention to provide an improved hybrid engine which has, at the same time, a high efficiency and a reduced environmental impact.

Another object of the invention is to provide an improved hybrid engine that has a reduced structural complexity.

Therefore, the specific object of the present invention forms a hybrid engine for powering a vehicle equipped with at least one driving wheel, said hybrid engine comprising: a compression device to compress, in use, a compressible fluid; an electric motor connected to said compression device so as to supply, in use, energy to said compression device to compress said compressible fluid; and an expansion device distinct from said compression device and comprising: a cylinder in fluid communication with said compression device to allow, in use, the transfer of a compressed fluid from said compression device to said cylinder; a piston movable with respect to said cylinder; and ignition means to trigger, in use, the combustion of a mixture comprising at least one comburent and at least one fuel, allowing the expansion of said mixture in said cylinder and the movement of said piston due to the effect of said expansion; where said piston is kinematically disconnected from said compression device and kinematically connectable, in use, to said driving wheel of said vehicle, so that all the kinetic energy produced by the movement of said piston is transferred to said driving wheel.

Further according to the invention, said compression device can be alternative or rotary.

Conveniently according to the invention, said hybrid engine can comprise passage means for the transfer of a compressed fluid from said compression device to said expansion device and an injection device for injecting at least one fuel into said passage means.

Further according to the invention, said passage means may comprise heat exchange means to allow, in use, the lowering of the temperature of said compressed fluid passing through said passage means.

Advantageously according to the invention, said injection device can be arranged downstream of said heat exchange means.

Conveniently according to the invention, said hybrid engine can comprise a pressure sensor to measure the pressure of a fluid in said passage means.

Preferably according to the invention, said electric motor is operatively connected to said pressure sensor and said hybrid motor comprises a switch operatively interconnected to said electric motor and said pressure sensor in such a way that said electric motor can be activated or deactivated, in use. , by said switch on the basis of the pressure detected by said pressure sensor.

Advantageously according to the invention, said vehicle can be of the type comprising an acceleration device for varying the power delivered by said hybrid engine, and said hybrid engine can comprise: a valve in said passage means configured to vary the flow of a passing fluid in said passage means and operatively connectable to said acceleration device; and processing means operably interconnectable, in use, between said valve and said acceleration device in such a way as to control the operation of said valve based on the power required from said hybrid engine.

Conveniently according to the invention, said vehicle can be of the type comprising an acceleration device for varying the power delivered by said hybrid engine, said electric motor can be operably connectable, in use, with said acceleration device and said hybrid engine can comprise a control device interconnectable, in use, between said electric motor and said acceleration device.

Still according to the invention, said pressure sensor can be operatively connected to said control device in such a way that said control device controls, in use, the operation of said electric motor based on the pressure detected by said pressure sensor.

The present invention will now be described for illustrative but not limitative purposes, according to its preferred embodiments, with particular reference to the figures of the attached drawings, in which: Figure 1A is a pressure-volume diagram relating to a traditional Otto cycle engine ;

Figure 1B shows the piston-cylinder system in the four main phases of an Otto cycle;

Figure 2 shows the phase of maximum expansion and the phase of maximum compression of a piston-cylinder system in an Otto cycle;

figure 3 shows the functioning of the “Scuderi” engine;

Figure 4 shows an operating diagram of a hybrid engine according to a first embodiment of the present invention;

Figure 5 shows three phases of the operation of the piston-cylinder system relating to the expansion phase of an engine according to the present invention;

Figure 6 is a pressure-volume diagram relating to the compression phase in a hybrid engine according to the invention;

Figure 7 is a pressure-volume diagram relating to the expansion phase in a hybrid engine according to the invention; And

Figure 8 shows an operating diagram of a hybrid engine according to a second embodiment of the invention.

With reference to Figure 4, 1 indicates a hybrid engine comprising a reciprocating compressor 2 equipped with a first piston-cylinder system 3 formed by a cylinder 4 and a piston 5 driven by an electric motor 6 by means of a linkage 7 of the connecting rod-crank type.

Connected to the top of the cylinder 4 are an intake duct 8 and an expulsion duct 9 communicating with an internal chamber 10 of the cylinder 4, respectively, by means of an intake valve 11 and an expulsion valve 12.

In particular, the intake duct 8 and the expulsion duct 9 allow, respectively, the introduction of air into the internal chamber 10 of the cylinder 4 and the expulsion of compressed air from the same chamber.

The expulsion duct 9 is also connected to a tank 13 for the accumulation of compressed air, in which a pressure sensor 14 is placed to measure the air pressure in the tank 13.

The tank 13 is also provided with a series of fins 15 for cooling the compressed air coming from the internal chamber 10 of the cylinder 4.

A check valve 16 is also provided on the expulsion duct 9 to prevent the return of air to the internal chamber 10.

The tank 13 is also electrically connected to the electric motor 6 by means of a first electrical connection line 17 on which a switch 19 is also provided.

The tank 13 is also connected, through a connecting duct 20, to a second piston-cylinder system 21 composed of a cylinder 22 and a piston 23 defining, with this cylinder 22, an internal chamber 24 with variable volume.

In the connection duct 20 a regulation valve 25 and an injector 26 are mounted, arranged downstream of this regulation valve 25, for the injection of a fuel such as petrol.

The regulating valve 25 is connected, through a second electrical connection line 27, to an acceleration device 28 of the vehicle on which the engine 1 is mounted.

On the second electrical connection line 27 there is an electronic processor 29 to manage the operation of the regulating valve 25 as a function of the required power signals received by the acceleration device 28.

In the area of intersection between the connection duct 20 and the cylinder 22 there is an intake valve 30 to regulate the flow of the mixture of air and fuel, under pressure, towards the internal chamber 24 of the cylinder 22.

In the cylinder 22 there is also a spark plug 31 for starting the combustion of the mixture of air and fuel in the internal chamber 24.

An exhaust duct 32 is also connected to the cylinder 22 via an exhaust valve 33 for the expulsion of the exhausted combustion fluids from the internal chamber 24.

The piston 23 is in turn connected, through a kinematics 34 of the connecting rod-crank type, to the crankshaft 35 of the aforementioned vehicle to transmit a rotary motion to the wheels 36 of the vehicle itself.

During each operating cycle of the hybrid engine 1 (see figure 5), the reciprocating compressor 2 powered by the electric motor 6 compresses a combustive fluid, for example air, which in turn passes into the tank 13 through the expulsion duct 9 until until the fluid present in the same tank 13 does not reach a predetermined threshold pressure value.

The activation command of the electric motor 6 that powers the reciprocating compressor 2 is supplied to the same electric motor 6 by the switch 19 based on the pressure detected in the tank 13 by the pressure sensor 14.

Therefore, the electric motor 6 will have to feed the reciprocating compressor 2 as long as the pressure in the tank 13 is lower than the aforementioned threshold pressure value.

This threshold pressure value corresponds to point 3 of the diagram represented in Figure 6, in which the section 1-2 and the section 2-3 respectively represent the injection and compression phases of the fluid.

From the tank 13 the fluid then passes into the cylinder 22 due to the difference in pressure when the intake valve 30 is opened; in particular, this occurs when the piston 23 reaches the highest point of its stroke, i.e. at the top dead center (TDC), i.e. when the volume of the internal chamber 24 of the cylinder 22 is minimal.

The passage of the fluid through the connection duct 20 is regulated by the regulation valve 25 based on the actual power required by the user through the acceleration device 28.

Specifically, the regulating valve 25 will be completely open if maximum power is required, or only partially open when less power is required.

In this way, the regulating valve 25 manages, that is to say, determines the suction pressure of the fluid mixture in the cylinder 22.

Before entering the cylinder 22, the fluid is enriched with a fuel, for example gasoline, through the injector 26.

As said, when the piston 23 is in the top dead center, the intake valve 30 is opened to allow the fluid mixture under pressure to pass from the connection duct 20 to the aforementioned internal chamber 24.

After a certain period of time, when the piston 23 is still close to the relative top dead center, the intake valve 30 closes thus interrupting the fluid-dynamic connection with the connection duct 20.

At this point, the spark plug 31 ignites a spark causing the pressure in the internal chamber 24 to increase due to the combustion of the fluid mixture, causing the piston 23 to push towards the lowest point, i.e. at bottom dead center (PMI) and thus generating work on the crankshaft 35.

In particular, when the piston 23 is in the aforementioned lower dead center, the volume of the internal chamber 24 is maximum.

When the piston 23 reaches the bottom dead center, the discharge valve 33 opens, allowing the expulsion of the exhausted fluid in the subsequent rising phase of the same piston 23.

When the piston reaches the top dead center again, the intake valve 30 reopens and the cycle restarts.

From the foregoing, it emerges that the work obtained as a result of combustion in cylinder 22 (see figure 7) can be fully exploited without having to use a part of it to compress the fluid for the next cycle, as is the case in classic internal combustion engines.

Figure 7 shows, in fact, a pressure-volume graph relating to what happens in the cylinder 22, in which the sections 7-3 ', 3'-4, 4-5-6 and 6-7 represent, respectively, the phases of injection, combustion of the fluid mixture, expansion and expulsion of the exhausted fluid.

Referring now to figure 8, 1 'indicates a second hybrid engine in accordance with a second embodiment of the invention.

This second hybrid motor 1 'is structurally identical to the hybrid motor 1 described above, except for the absence of the regulating valve 25 and the tank 13 and for the various functional connections involving the electric motor, the connection duct and the device acceleration.

In fact, unlike the hybrid engine 1, in the second hybrid engine 1 'the acceleration device 28' is functionally connected, through a first connection line 29 ', to an electronic processor 30' which is in turn connected, functionally, both to the electric motor 6 'by means of a second connection line 31' on which a control device 32 'is provided, such as an inverter, and to the connection duct 20' by means of a third connection line 33 'to which the pressure sensor 14 '.

Furthermore, in the second hybrid engine 1 ', the connection duct 20' has fins 15 'for cooling the comburent coming from the cylinder 4', arranged upstream of the injector 26 'for the injection of fuel in the same connection duct 20 '.

In the second hybrid engine 1 ', the pressure in the connection duct 20' is dynamically adjusted.

The electronic processor 30 'continuously sends command signals to the control device 32' so that it regulates, at any instant, the number of revolutions of the electric motor 6 'according to the power required by the user through the acceleration device 28' and the pressure measured in the connection duct 20 'by the pressure sensor 14'.

By varying the number of revolutions of the electric motor 6 ', the flow rate of the fluid exiting the cylinder 4' can be increased or decreased, and in this way the pressure in the connection duct 20 'can therefore be varied.

As emerges from the foregoing, the hybrid engine according to the present invention has a compression device and an expansion device that are mechanically separated from each other, unlike traditional internal combustion engines, in which the compression and expansion phases take place in the same cylinder, and by the “Scuderi” engines in which the two pistons provided for the compression and expansion phases, while moving inside different cylinders, are mechanically connected to the same crankshaft.

By comparing, for example, the engine according to the invention with a typical internal combustion engine, for example a four-stroke engine, the work obtained following combustion in the cylinder 22 can be fully exploited by the user, while in a Internal combustion engine Part of the work obtained as a result of combustion must be reused to compress the fluid for the next cycle.

Comparing, again, the engine according to the invention to a normal four-stroke engine, since the compression takes place in a separate unit with respect to the expansion unit, the piston-cylinder system relating to the expansion phase can perform work at each revolution of the 'crankshaft, while in a four-stroke engine work can only be delivered every 2 revolutions of the crankshaft.

Furthermore, as mentioned above, unlike normal internal combustion engines, the piston-cylinder system of the engine according to the invention, relating to the expansion phase, does not have to perform compression work and therefore this piston-cylinder system can be designed in a totally independent manner. from the compression unit and therefore sized in such a way as to minimize the portion 5-6 shown in Figure 7, corresponding to the phase of end expansion.

The fluid, when it is in the conditions referred to in point 5 of the diagram of Figure 7, in fact has a residual energy that cannot be exploited since the piston has finished its stroke.

It is therefore desirable to minimize this phase of end expansion to make the most of the energy of the fluid.

In classic internal combustion engines, the stroke of the piston in the compression phase is equal to that of expansion, and for this reason it is difficult to reduce the extent of the aforementioned end-of-expansion phase.

In the engine according to the present invention, however, the stroke of the piston in the expansion phase can be adjusted without restrictions, since the device that carries out the expansion is mechanically disconnected from the one that allows compression.

The fact that in the engine proposed here the compression device is mechanically disconnected from the expansion device also allows for lower vibrations on the crankshaft, even with respect to the "Scuderi" engine, and also to obtain a system that is structurally more flexible than the traditional engines, such as to allow for example also the replacement of the piston-cylinder system provided for the compression phase with a rotary compressor.

According to a further aspect of the invention, the provision of the electric motor to power the compressor makes it possible to significantly reduce harmful emissions to the environment and therefore reduce the environmental impact of the engine.

Furthermore, in the engine according to the invention, combustion in the cylinder takes place at relatively low temperatures thanks to the provision of the cooling fins upstream of this cylinder.

It follows that in this way the combustion takes place more efficiently, also in terms of less pollution produced.

In fact, at high temperatures the formation of pollutants dangerous for human health, such as carbon monoxide and nitrogen oxides, is favored.

In addition to what has just been said, making combustion occur at low temperatures significantly reduces the risk of incurring the phenomenon of dissociation, which, if it occurs, would not allow to exploit all the potential energy of combustion due to heat " concealed ".

The term "dissociation" normally means the phenomenon according to which when the combustion temperature exceeds a certain threshold value, the dissociation of carbon dioxide and the absorption of heat by the reaction are obtained.

The heat that develops during combustion is therefore less than ideal, as a part of it is used in the dissociation reaction.

Therefore, in these cases the combustion is not complete and there will be some heat that has not developed.

As for gasoline, for example, this phenomenon occurs around 2300 ° K.

Furthermore, the fact that the cooling fins of the engine according to the invention have been provided upstream of the fuel injector makes it possible to avoid the risk of detonation of the fluid, since the fuel is added to the comburent after the latter has cooled. .

The present invention has been described for illustrative, but not limitative purposes, according to its preferred embodiments, but it is to be understood that variations and / or modifications may be made by those skilled in the art without thereby departing from the relative scope of protection, such as defined by the attached claims.

Claims (10)

CLAIMS 1. Hybrid engine (1.1 ') for powering a vehicle equipped with at least one drive wheel, called hybrid engine (1.1') including: - a compression device (2) to compress, in use, a compressible fluid; - an electric motor (6, 6 ') connected to said compression device (2) so as to provide, in use, energy to said compression device (2) to compress said compressible fluid; And - an expansion device (21) distinct from said compression device (2) and comprising: a cylinder (22) in fluid communication with said compression device (2) to allow, in use, the transfer of a compressed fluid from said compression device (2) to said cylinder (22); a piston (23) movable with respect to said cylinder (22); And ignition means (31) to trigger, in use, the combustion of a mixture comprising at least one comburent and at least one fuel, allowing the expansion of said mixture in said cylinder (22) and the movement of said piston (23) to effect of said expansion; where said piston (23) is kinematically disconnected from said compression device (2) and kinematically connectable, in use, to said driving wheel of said vehicle, so that all the kinetic energy produced by the movement of said piston (23 ) is transferred to said driving wheel. 2. Hybrid engine (1, 1 ') according to claim 1, characterized by the fact that said compression device (2) is reciprocating or rotary. Hybrid engine (1, 1 ') according to claim 1 or 2, characterized in that it comprises passage means (9, 13, 20; 20') for transferring a fluid compressed by said compression device (2) to said expansion device (21) and an injection device (26, 26 ') for injecting at least one fuel into said passage means (9, 13, 20; 20'). 4. Hybrid engine (1, 1 ') according to claim 3, characterized in that said passage means (9, 13, 20; 20') comprise heat exchange means (15, 15 ') to allow, in use , the lowering of the temperature of said compressed fluid passing through said passage means (9, 13, 20; 20 '). 5. Hybrid engine (1, 1 ') according to claim 4, characterized by the fact that said injection device (26, 26') is arranged downstream of said heat exchange means (15, 15 '). 6. Hybrid engine (1, 1 ') according to any one of claims 3 to 5, characterized in that it comprises a pressure sensor (14, 14') for measuring the pressure of a fluid in said passage means (9, 13 , 20; 20 '). Hybrid motor (1) according to claim 6, characterized in that said electric motor (6) is operatively connected to said pressure sensor (14) and by the fact that it comprises a switch (19) operatively interconnected to said electric motor ( 6) and to said pressure sensor (14) so that said electric motor (6) can be activated or deactivated, in use, by said switch (19) based on the pressure detected by said pressure sensor (14). Hybrid engine (1) according to any one of the preceding claims, characterized in that said vehicle is of the type comprising an acceleration device (28) for varying the power delivered by said hybrid engine (1) and in that said hybrid engine (1) includes: - a valve (25) in said passage means (9, 13, 20) configured to vary the flow of a fluid passing through said passage means (9, 13, 20) and operatively connectable to said acceleration device (28) ; And - processing means (29) operatively interconnectable, in use, between said valve (25) and said acceleration device (28) in such a way as to control the operation of said valve (25) based on the power required of said hybrid engine (1). Hybrid engine (1 ') according to claim 6, characterized in that said vehicle is of the type comprising an acceleration device (28') for varying the power delivered by said hybrid engine (1), in that said electric motor (6 ') is operatively connectable, in use, with said acceleration device (28') and by the fact that said hybrid motor (1 ') comprises a control device (32') which can be interconnected, in use, between said motor electric (6 ') and said acceleration device (28'). 10. Hybrid engine (1 ') according to claim 9, characterized in that said pressure sensor (14') is operatively connected to said control device (32 ') in such a way that said control device (32') controls , in use, the operation of said electric motor (6 ') on the basis of the pressure detected by said pressure sensor (14').