GB2592864A

GB2592864A - Improved hybrid engine

Info

Publication number: GB2592864A
Application number: GB1915389.9A
Authority: GB
Inventors: Iannuzzi Sabino
Original assignee: Individual
Current assignee: Individual
Priority date: 2018-10-24
Filing date: 2019-10-23
Publication date: 2021-09-15
Also published as: IT201800009735A1; GB201915389D0

Abstract

An engine 1 to power a vehicle. The engine (referred to as a hybrid engine) comprising: a compression device 2; an electric motor 6 to drive the compressor 2; and an expansion device 21 distinct from said compressor and comprising: a cylinder 22 in fluid communication with the compressor to allow transfer of a fluid (eg air) to the cylinder; a piston 23 movable with respect to said cylinder; and means of ignition 31 to trigger the combustion in the cylinder and cause movement of the piston. The piston 23 is disconnected from the compression device and connected, in use, to a driving wheel of said vehicle. Further disclosed is a tank 13 to store the pressurised air from the compressor, and a control mechanism to turn the electric motor powering the compressor on or off depending on the air pressure within the tank.

Description

IMPROVED HYBRID ENGINE

This invention concerns an improved hybrid engine. In more detail, the invention concerns a hybrid engine intended, preferably, for driving vehicles.

In the automotive sector, fuel-fuelled engines, i.e. internal combustion engines, also briefly referred to by the acronym "ICE", or sometimes "hybrid" systems, in which an internal combustion engine and an electrically powered engine transmit work to the wheels of the vehicle, are now widely used to provide work to the wheels of vehicles.

Internal combustion engines use the pressure generated by the combustion of a mixture of a fuel and a combustion agent to set in motion a moving part, generally a sliding piston 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 one 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 bottom and top dead centre, respectively indicated with "BDC" and "TDC" in figure 2.

In the pressure-volume diagram of figure 1A the thermodynamic transformations of a cycle Otto are shown, while in figure 1B the configurations of the piston-cylinder system in the various phases of the cycle Otto are shown.

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

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

For example, if you take an engine running on an Otto cycle, to improve thermodynamic efficiency you would need to increase the compression ratio, but this is not possible.

One of the reasons that prevents this improvement is that for high values of the compression ratio, the mixture composed of air and gasoline "detonates", causing damage to the engine parts and not allowing optimal combustion, because for high values of the compression ratio the pressure and therefore the temperature of the end compression exceed the autoignition conditions (see point 3 in the diagram in 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 and expansion phases; because of this design limitation, when the piston reaches its -3 -lowest point in the expansion phase, the fuel/combustion mixture contains a residual energy that cannot be actively exploited (see phase 5-2 in figure 1A).

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

In particular, the Scuderi engine operates with an Otto cycle divided into two parts that take place within 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 into a second cylinder called "hot", where there is a spark plug to start combustion and the following expansion of the fluid.

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

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

However, the Scuderi engine has several disadvantages, such as the considerable vibrations transmitted to the crankshaft.

The possibility of optimizing the stroke of the -4 -expansion and compression pistons is also limited by the same construction architecture of the Scuderi engine, which prevents separate intervention on the piston-cylinder systems relating to the phases of compression and expansion.

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

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

The higher the combustion temperature, the greater the amount of CO and NOx produced and therefore released into the atmosphere.

This shows, therefore, the need to find ways to improve the efficiency and quality of combustion.

In order to reduce the pollutants produced by the vehicle, it is common practice 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 "hybrids", are equipped with devices for selecting the engine to be used preferably and require that the internal combustion engine and the electric motor are connected to the same transmission shaft.

Such a system generally ensures improvements in terms of pollutant emissions; however, it is characterised by a certain engineering complexity, which has a negative impact both on manufacturing costs -5 -and on the weight of the vehicle.

In the light of the above, it is therefore the aim of this invention to provide an improved hybrid engine that is both highly efficient and environmentally friendly.

Another purpose of the invention is to provide an improved hybrid engine with reduced structural complexity.

Therefore, the specific object of the present invention is a hybrid motor for the power supply of a vehicle equipped with at least one driving wheel, called hybrid motor, including: a compression device for compressing, during use, a compressible fluid; an electric motor connected to said compression device so as to supply, during use, energy to said compression device for compressing said compressible fluid; and an expansion device distinct from said compression device and comprising: a cylinder in fluid communication with that compression device to permit, in use, the transfer of a compressed fluid from that compression device to that cylinder; a piston moving in relation to that cylinder; and means of initiation to initiate, in use, the combustion of a mixture comprising at least one oxidiser and at least one fuel, permitting the expansion of that mixture in that cylinder and the movement of that piston as a result of that expansion; where that piston is kinematically disconnected from that compression device and kinematically connected, in use, to that driving wheel of that vehicle, in such a way that all the kinetic energy produced by the -6 -movement of that piston is transferred to that driving wheel.

Further, depending on the invention, that compression device may be alternative or rotary.

According to the invention, that hybrid engine may, as appropriate, include means of transfer of a compressed fluid from that compression device to that expansion device and an injection device for injecting at least one fuel into those means of transfer.

Further according to the invention, such means of passage may include means of heat exchange to enable, in use, the temperature of that compressed fluid passing through such means of passage to be lowered.

Advantageously according to the invention, this injection device may be placed downstream of these means of heat exchange.

Conveniently according to the invention, such a hybrid engine may include a pressure sensor to measure the pressure of a fluid in such means of passage.

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

Advantageously according to the invention, that vehicle may be of the type comprising an acceleration device to vary the power supplied by that hybrid -7 -engine, and that hybrid engine may comprise: a valve in those means of passage configured to vary the flow of a fluid passing through those means of passage and operationally connectable to that acceleration device; and means of processing operationally interconnectable, in use, between that valve and that acceleration device in such a way as to control the operation of that valve according to the power required of that hybrid engine.

According to the invention, that vehicle may be of the type comprising an acceleration device for varying the power supplied by that hybrid motor, that electric motor may be operationally connected, in use, with that acceleration device and that hybrid motor may include a control device which, in use, may be interconnected between that electric motor and that acceleration device.

Again according to the invention, that pressure sensor may be operationally connected to that control device in such a way that that control device controls, in use, the operation of that electric motor on the basis of the pressure detected by that pressure sensor.

The present invention will now be described by way of illustration but not limited to, according to its preferred forms of realization, with particular reference to the figures in the attached drawings, in which: figure 1A is a pressure-volume diagram relative to a traditional Otto cycle engine; Figure 1B shows the piston-cylinder system in the four main phases of an Otto cycle; -8 -Figure 2 shows the maximum expansion phase and the maximum compression phase of a piston-cylinder system in an Otto cycle; Figure 3 shows the operation of the "Scuderi" engine; Figure 4 shows a scheme of operation of a hybrid engine according to a first form of realization of the present invention; Figure 5 shows three phases of the operation of the piston-cylinder system related 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 related to the expansion phase in a hybrid engine according to the invention; and Figure 8 shows a scheme of operation of a hybrid engine according to a second form of realization of the invention.

Referring to figure 4, with 1 is indicated a hybrid engine comprising an reciprocating compressor 2 equipped with a first system piston-cylinder 3 formed by a cylinder 4 and a piston 5 driven by an electric motor 6 through a kinematic mechanism 7 of the type connecting rod-hand crank.

A suction line 8 and an expulsion line 9 are connected to the top part of cylinder 4, communicating with an internal chamber 10 of cylinder 4, respectively, by means of a suction valve 11 and an expulsion valve 12. -9 -

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

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

In addition, tank 13 is equipped with cooling wings 15 for cooling the compressed air coming from the internal chamber 10 of cylinder 4.

On the exhaust duct 9 there is also a non-return valve 16 to prevent the return of air to the inner chamber 10.

In addition, tank 13 is electrically connected to electric motor 6 via a first electrical connection line 17, on which a switch 19 is also provided.

Tank 13 is also connected, by means of a connection duct 20, to a second piston-cylinder system 21 consisting of a cylinder 22 and a piston 23 defining, with this cylinder 22, an internal chamber 24 with variable volume.

In the connection line 20 there is a regulating valve 25 and an injector 26, located downstream of this regulating valve 25, for the injection of a fuel such as gasoline.

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

On the second electrical connection line 27 there is a computer 29 to manage the operation of the control valve 25 according to the power signals required received by the acceleration device 28.

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

Cylinder 22 also contains a spark plug 31 for starting the combustion of the air-fuel mixture in the inner chamber 24.

Cylinder 22 is also connected to an exhaust duct 32 via an exhaust valve 33 for the expulsion of combustion exhaust fluids from the inner chamber 24.

Piston 23 is in turn connected, by means of a 34 kinematic mechanism of the crank-rod type, to the crankshaft 35 of the said vehicle to transmit a rotary motion to the wheels 36 of the said vehicle.

During each operating cycle of the hybrid motor 1 (see figure 5), the reciprocating compressor 2 powered by the electric motor 6 compresses a combustion fluid, e.g. air, which in turn passes into tank 13 through the exhaust pipe 9 until the fluid in the same tank 13 reaches a predetermined threshold pressure value.

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

Therefore, the electric motor 6 must supply the reciprocating compressor 2 as long as the pressure in tank 13 is lower than the aforementioned threshold pressure value.

This threshold pressure value corresponds to point 3 of the diagram shown in figure 6, in which section 12 and section 2-3 respectively represent the phases of fluid inlet and compression.

From tank 13 the fluid passes, therefore, in cylinder 22 due to the pressure difference when the suction valve 30 is opened; in particular, this happens when piston 23 reaches the highest point of its stroke, i.e. the top dead centre (TDC), that is when the volume of the internal chamber 24 of cylinder 22 is minimum.

The flow of fluid through the connection line 20 is regulated by the control valve 25 according to the actual power required by the user through the acceleration device 28.

Specifically, the control valve 25 will be fully open when the maximum power is required, or only partially open when a lower power is required.

In this way, the control valve 25 manages, i.e. determines the suction pressure of the fluid mixture in cylinder 22.

Before entering cylinder 22, the fluid is enriched with a fuel, e.g. petrol, via injector 26.

As mentioned above, when piston 23 is in the top dead centre, the intake valve 30 is opened to allow the fluid mixture under pressure to pass from the connection pipe 20 to the said inner chamber 24.

After a certain period of time, when piston 23 is still near its top dead center, the intake valve 30 -12 -closes, thus interrupting the fluid-dynamic connection with the connection pipe 20.

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

In particular, when piston 23 is in the above-mentioned bottom dead center, the volume of the inner chamber 24 is maximum.

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

When the piston reaches the top dead centre again, the suction valve 30 opens again and the cycle starts again.

From the above, it emerges that the work obtained following combustion in cylinder 22 (see figure 7) can be fully exploited withcut 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 relative to what happens in cylinder 22, in which the sections 7-3', 37-4, 4-5-6 and 6-7 represent, respectively, the phases of introduction, combustion of the fluid mixture, expansion and expulsion of the used fluid.

Referring now to figure 8, with l' is indicated a second hybrid engine according to a second form of realization of the invention.

This second hybrid engine 1' is structurally identical to the hybrid engine 1 described above, except for the absence of the regulation valve 25 and the tank 13 and for the different functional connections that affect the electric motor, the connection pipe and the acceleration device.

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

In addition, in the second l' hybrid motor, the 20' connecting duct has 15' fins for cooling the combustion from the 4' cylinder, arranged upstream of the 26' injector for fuel injection into the same 20' connecting duct.

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

The 30' electronic signal conditioning instrument continuously sends control signals to the 32' control device so that it can adjust the speed of the 6' electric motor at any time according to the power required by the user via the 28' acceleration device and the pressure measured in the 20' connection line by -14 -the 14' pressure sensor.

By varying the speed of the 6' electric motor, the flow rate of the fluid leaving the 4' cylinder can be increased or decreased, and in this way the pressure in the 20' connection line can be varied.

As it emerges from the above, the hybrid engine according to the present invention has a compression device and an expansion device mechanically separated from each other, unlike the traditional internal combustion engines, in which the compression and expansion phases occur in the same cylinder, and from the "Scuderi" engines in which the two pistons provided for the compression and expansion phases, while moving within different cylinders, are mechanically connected to the same crankshaft.

Comparing, for example, the engine according to the invention with a typical internal combustion engine, for example a four-stroke engine, one has that the work obtained as a result of combustion in cylinder 22 is fully exploitable by the user, while in an 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 occurs in a separate unit with respect to the expansion unit, the piston-cylinder system relative to the expansion phase can deliver work at each turn of the crankshaft, while in a four-stroke engine work can be delivered only every 2 revolutions of the crankshaft.

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

The fluid, when it is in the conditions of which to the point 5 of the diagram of the figure 7, introduces in fact a residual energy that cannot be exploited in how much the piston has finished its run.

It is therefore desirable to minimise this end of expansion phase in order 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 this phase of end expansion.

In the engine according to the present invention, instead, the stroke of the piston in the expansion phase can be regulated without restrictions, as the device that realizes the expansion is mechanically disconnected from the one that allows the compression.

The fact that in the engine proposed here the compression device is mechanically disconnected from the expansion device allows, moreover, to have less vibrations on the crankshaft, even compared to the engine "Scuderi", and also to obtain a system structurally more flexible than 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 another aspect of the invention, the prediction of the electric motor to power the compressor allows to significantly reduce emissions harmful to the environment and thus reduce the environmental impact of the engine.

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

As a result, combustion takes place more efficiently, also in terms of less pollution.

At high temperatures, the formation of pollutants dangerous to human health, such as carbon monoxide and nitrogen oxides, is encouraged.

In addition to what has just been satd, making combustion take place at low temperatures significantly reduces the risk of incurring the phenomenon of dissociation, which, if it were to occur, would not allow the full energy potential of combustion to be exploited due to a "hidden" heat.

The term "dissociation" normally refers to the phenomenon that when the combustion temperature exceeds a certain threshold value, carbon dioxide is dissociated, and heat is absorbed by the reaction.

The heat that develops during combustion is -17 -therefore lower than the ideal heat, as part of it is used in the dissociation reaction.

Therefore, in these cases the combustion is not complete and there will be a certain amount of heat that has not developed.

As far as gasoline is concerned, for example, this phenomenon occurs around 2300°K.

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

The present invention has been described to illustrative title, but not limitative, according to its preferred forms of realization, but it is to be intended that variations and/or modifications can be brought from the experts of the branch without for this to leave from the relative field of protection, as defined by the attached claims.

Claims

-18 -CLAIMS1. Hybrid engine (1, 1') to power a vehicle equipped with at least one driving 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) separate 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 in relation to said cylinder (22); and means of initiation (31) to initiate, in use, the combustion of a mixture comprising at least one oxidiser and at least one fuel, thereby permitting the expansion of that mixture into that cylinder (22) and the movement of that piston (23) as a result of that expansion; where said piston (23) is kinematically disconnected from said compression device (2) and kinematically connected, in use, to said driving wheel of said vehicle, in such a way 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, characterised by the fact that the compression device (2) is alternative or rotary.
3. Hybrid engine (1, 1') according to claim 1 or 2, characterised by the fact that it includes means of passage (9, 13, 20; 20') for the transfer of a compressed fluid from said compression device (2) to said expansion device (21) and an injection device (26, 26') for injecting at least one fuel into said means of passage (9, 13, 20; 20').
4. Hybrid engine (1, 1') according to claim 3, characterized by the fact that these means of passage (9, 13, 20; 20') include means of heat exchange (15, 15') to allow, in use, the lowering of the temperature of said compressed fluid passing through said means of passage (9, 13, 20; 20').
S. Hybrid engine (1, 1') according to claim 4, characterized by the fact that said injection device (26, 26') is placed downstream of said means of heat exchange (15, 15').
6. Hybrid engine (1, 1') according to any of the claims 3 to 5, characterized by the fact of including a pressure sensor (14, 14') to measure the pressure of a fluid in said means of passage (9, 13, 20; 20').
7. Hybrid motor (1) according to claim 6, characterised by the fact that said electric motor (6) is operationally connected to said pressure sensor (14) and by the fact that it includes a switch (19) operationally connected to said electric motor (6) and to said pressure sensor (14) in such a way that said electric motor (6) can be activated or deactivated, in use, by said switch (19) according to the pressure detected by said pressure sensor (14).
8. Hybrid engine (1) according to any of the above claims, characterised by the fact that this vehicle is of the type comprising an acceleration device (28) to vary the power output of said hybrid engine (1) and by the fact that said hybrid engine (1) comprises: - a valve (25) in said means of passage (9, 13, 20) configured to vary the flow of a fluid passing through said means of passage (9, 13, 20) and operationally connectable to said acceleration device (28); and - means of processing (29) operationally 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) according to the power required of said hybrid engine (1).
9. Hybrid engine (1') according to claim 6, characterized by the fact that said vehicle is of the type including an acceleration device (28') to vary the power output of said hybrid engine (1), by the fact that said electric motor (6') is operationally connectable, in use, with said acceleration device (28') and by the fact that said hybrid engine (1') includes a control device (32') interconnectable, in use, between said electric motor (6') and said acceleration device (28').
10. Hybrid motor (1') according to claim 9, characterized by the fact that said pressure sensor (14') is operationally connected to said control device -21 - (32') in such a way that said control device (32') controls, in use, the operation of said electric motor (6') according to the pressure detected by said pressure sensor (14').