WO2009144757A1

WO2009144757A1 - Engine unit

Info

Publication number: WO2009144757A1
Application number: PCT/IT2008/000364
Authority: WO
Inventors: Giorgio Ferigo; Massimo Ceccarani; Francesco Verganti
Original assignee: Giorgio Ferigo; Massimo Ceccarani; Francesco Verganti
Priority date: 2008-05-30
Filing date: 2008-05-30
Publication date: 2009-12-03

Abstract

An engine unit (1) comprises an internal combustion engine (2), having an inlet duct (5) into at least one combustion chamber (4), and a regenerative blower (3) connected to the engine (2) inlet duct (5) in such a way as to supply compressed air to the engine (2). The engine (2) has a number of cylinders less than or equal to six and a cylinder capacity of between 40 and 2200 cc; and the regenerative blower (3) has a compression ratio which is less than or equal to 1.6.

Description

Engine unit

Technical Field

The present invention relates to an engine unit and, in particular, an engine unit comprising an internal combustion engine into whose intake duct compressed air from a blower is introduced.

Background Art

As is known, to increase the power (and torque supplied) of an internal combustion engine, or endothermic engine, without increasing its cylinder capacity and without reaching very high revolving speeds, in many cases supercharging is used.

Supercharging allows the engine to be supplied with the comburent (or already the fuel - comburent mixture, if the blower compresses said mixture directly) in conditions of density greater than that corresponding to the intake environment. Therefore, subject to adjustment of the fuel feed system (to guarantee the correct comburent - fuel ratio), a greater quantity of fuel - comburent mixture per unit of volume is introduced into the engine combustion chamber.

In this way, during the engine operating cycle, each intake step sees the introduction of a quantity of comburent (and consequently, fuel - comburent mixture) clearly greater than that which could enter if no blower were used, that is to say, if engine intake were at atmospheric pressure. Consequently, at each working step of the engine operating cycle, a greater quantity of heat is released and therefore the mechanical work obtained is also greater. Therefore, the torque and power, at the same revolving speed, are higher than those in the aspirated version (that is to say, without blower) of the same engine.

Supercharging of internal combustion engines has been known for some time and is obtained mainly by using two types of blowers: blowers mechanically driven by an engine to which they are connected (which may be the same internal combustion engine or a drive unit used specially for the blower) and blowers driven by the exhaust gases of the internal combustion engine. As is known, the first type includes piston blowers, rotary vane blowers, Lysholm blowers, Wankel blowers, Scroll (orbiting spiral) blowers, Roots blowers and centrifugal blowers. In contrast, the second type mainly includes exhaust-turbo blower type superchargers. Finally, there are mixed type blowers, that is to say, driven both mechanically by the engine and by the exhaust gases (Comprex system or pressure wave blowers).

The blowers used by the engine unit which is the subject of the present invention are included in the first type, that is to say, they are blowers mechanically driven by an engine.

According to the prior art, the use of supercharging with an exhaust-turbo blower type supercharger has several disadvantages and limitations on use.

First, such supercharging systems are solutions which are difficult to apply in engines which have a medium - small cylinder capacity (and, in particular, in motor vehicles). The dimensions are large, the weight not negligible, the costs considerable.

Secondly, in order to be able to achieve optimum performance, high turbine and consequently engine revolving speeds must be reached. Finally, in such solutions very high temperatures (even above 900°C) have to be managed. Moreover, in the case of the use of mechanically driven blowers (for example, Roots blowers), precision synchronisation of the moving parts is required and high precision in the mechanical working of the various components. All of these requirements, with the respective costs of production and/or installation, make the use of such systems not very advantageous, as already indicated, for engines which have a medium - small cylinder capacity, and, in particular, for motor vehicle engines.

Disclosure of the Invention

In this situation, the technical purpose which forms the basis of the present invention is to provide an engine unit which overcomes the above-mentioned disadvantages. hi particular, the technical purpose of the present invention is to provide an engine unit with air supercharging, the supercharging system having dimensions and weights which are optimum for engines which have a medium - small cylinder capacity, and, in particular, for motor vehicle engines.

Another aim of the present invention is to reduce exhaust emissions and consumption compared with prior art engine units, with the same maximum power achieved.

Moreover, the present invention has for an aim to allow four-stroke engines to be used where currently two-stroke engines have to be used.

Finally, another technical purpose of the present invention is to provide an engine unit which is reliable and has a relatively low cost.

These aims and others, more apparent in the description which follows, are achieved by an engine unit comprising the technical features described in one or more of the claims herein.

Brief Description of the Drawings

Further features and advantages of the invention are more apparent from the detailed description of a preferred, non-limiting embodiment of an engine unit according to the present invention.

The invention is described below with reference to the accompanying drawings, provided by way of example only and, therefore, without limiting the scope of the invention, and in which:

Figure 1 is a block diagram of the components of an engine unit made in accordance with the present invention; Figure 2 is a side view, partly in cross-section, of a first embodiment of an engine unit made in accordance with the present invention;

Figure 3 is a side view, partly in cross-section, of a second embodiment of an engine unit made in accordance with the present invention; Figure 4 is a side view, partly in cross-section, of a third embodiment of an engine unit made in accordance with the present invention;

Figure 5 is a side view, partly in cross-section, of a fourth embodiment of an engine unit made in accordance with the present invention;

Figure 6 is an axonometric view, partly in cross-section, of a regenerative blower, which can be used in an engine unit made in accordance with the present invention;

Figure 7 is a side view, of a first embodiment of a section of the annular channel of the regenerative blower, which can be used in an engine unit made in accordance with the present invention; Figure 8 is a side view, of a second embodiment of a section of the annular channel of the regenerative blower, which can be used in an engine unit made in accordance with the present invention;

Figure 9 is a side view, of a third embodiment of a section of the annular channel of the regenerative blower, which can be used in an engine unit made in accordance with the present invention;

Figure 10 is a side view, of a fourth embodiment of a section of the annular channel of the regenerative blower, which can be used in an engine unit made in accordance with the present invention;

Figure 11 is an axonometric view of an impeller of the regenerative blower made in accordance with the first embodiment of Figure 7;

Figure 12 is an axonometric view of an impeller of the regenerative blower made in accordance with the second embodiment of Figure 8;

Figure 13 is an axonometric view of an impeller of the regenerative blower made in accordance with the third embodiment of Figure 9; Figure 14 is an axonometric view of an impeller of the regenerative blower made in accordance with the fourth embodiment of Figure 10;

Figure 15 is a side view, partly in cross-section, of the regenerative blower made in accordance with the first embodiment of Figure 7;

Figure 16 is a side view of the section of the annular channel of the regenerative blower used in tests in the field;

Figure 17 is a graph of the power developed by the internal combustion engine used in the tests in the field, in the four condition in which the tests were carried out;

Figure 18 is a graph of the torque supplied by the internal combustion engine used in the tests in the field, in the four condition in which the tests were carried out;

Figure 19 is a graph showing the internal combustion engine air intake flow rate, for the engine used in the test in the field, in the absence of the regenerative blower; and Figure 20 is a graph showing the air flow rate supplied by the regenerative blower connected to the internal combustion engine used in the tests in the field.

Detailed Description of the Preferred Embodiments of the Invention

With reference to the accompanying drawings, the numeral 1 denotes an engine unit made in accordance with the present invention.

The engine unit 1 basically comprises an internal combustion engine 2 and a regenerative blower 3 connected to it.

The engine 2 has at least one combustion chamber 4 (in the case in question illustrated in the accompanying drawings) in which combustion takes place of a mixture of a fuel (traditionally consisting of hydrocarbons) and a comburent (that is to say, the oxygen contained in the air). Air is introduced into the combustion chamber 4 through a suitable inlet duct 5 (used to schematically illustrate the entire comburent feed system from the regenerative blower 3 to the engine 2 combustion chamber 4). The regenerative blower 3 is connected to said inlet duct 5 in such a way as to supply air (or, if the blower compresses the comburent mixture, the fuel - comburent mixture) with greater density (therefore with higher mass flow values) to the engine 2. The regenerative blower 3 is used to introduce into the combustion chamber 4 a greater air mass flow and therefore, with suitable adjustment of the fuel feed system (to maintain the correct comburent - fuel ratio), a greater quantity of comburent mixture than is possible with normal aspirated intake.

The basic structure of the regenerative blower 3 (also known as a side channel, peripheral channel or ring blower or turbine) consists of a body 6 and an impeller 7. The impeller 7 has a plurality of blades 8, distributed along a peripheral circumferential band.

The regenerative blower 3 has at least one annular chamber 9, formed partly by the body 6 and partly by the impeller 7. During impeller 7 rotation, the blades 8 rotate inside the annular chamber 9. Along most of its length, the latter has a cross-section noticeably greater than the width of the blades 8.

To separate the intake side from the delivery side of the regenerative blower 3, the part of the annular chamber 9 formed by the body 6 has a reduction 10 in its cross-section (usually substantially cancelling the cross-section). In this way, at the reduction 10 in the cross-section, the annular chamber 9 is substantially reduced to a passage for the impeller 7 blades 8 (said passage for the blades 8 is commonly known as a "stripper").

During impeller 7 rotation, the blades 8 impart a radial acceleration to the air contained in the annular chamber 9. Having flown away from the impeller, the air is then pushed against the part of the annular chamber 9 formed by the body 6, by which it is deflected and lead back between the impeller 7 blades 8. In this way, the air sucked in not only follows the rotation of the impeller 7 but also follows a spiral path through the annular chamber 9, passing through the impeller 7 blades 8 several times during its path from the regenerative blower 3 infeed to the outfeed.

In accordance with the present invention, regenerative blowers may be in various embodiments, some of which are illustrated in the accompanying drawings.

In a first embodiment (Figures 6, 7, 11 and 15) and in a second embodiment (Figures 8 and 12), the regenerative blower 3 has a single annular chamber 9.

In the first embodiment, one half-ring of the annular chamber 9 is formed by the body 6 and the other half-ring is formed by the impeller 7. hi the half-ring formed by the impeller 7 there are a predetermined number of compartments 11, created using walls 12 with minimum thickness positioned radially (said walls 12 form the blades 8). When the impeller 7 turns, a radial acceleration is imparted to the air contained in these compartments 11. Thanks to the shape of the compartments 11, the air flow is deflected in a direction for exiting the impeller 7 substantially parallel with the axis of the impeller 7. Having flown away from the impeller 7, the air enters the half-ring formed by the body 6, by which it is deflected and lead back into the impeller 7 compartments 11 , which it enters so that it can be subjected to another acceleration. The second embodiment differs from the first in that the impeller 7 does not form a complete half-ring of the annular chamber 9, but instead only forms part of it. Consequently, the body 6, in addition to the half-ring of the annular chamber 9 of the first embodiment, also forms the outermost part of the other half-ring of the annular chamber 9. In a third embodiment (Figures 9 and 13) and in a fourth embodiment

(Figures 10 and 14), the regenerative blower 3 has a double annular chamber 13, which may be considered as joining two parallel communicating annular chambers 9, in which the impeller 7 is positioned at the centre between the two annular chambers 9, the two faces of the impeller forming the wall shared by both annular chambers 9. Therefore, during impeller 7 rotation, the blades 8 simultaneously act in both annular chambers 9, according to methods similar to those indicated above relative to the single annular chamber 9.

The third and fourth embodiments differ from each other due to the fact that in the third embodiment the blades 8 are only positioned on the two faces of the impeller 7 peripheral circumferential band (Figures 9 and 13), whilst in the fourth embodiment the blades 8 also extend radially on the outside of the impeller 7 (Figures 10 and 14).

Advantageously, other embodiments of the regenerative blower 3 are also possible. The shape of the channel may vary, the angle and shape of the impeller 7 may be different and, more particularly, those of the blades, two or more impellers may be assembled coaxially, with the possibility of the multi-stage device obtained in this way operating parallel or in series.

Internal combustion engines which can be used in the engine unit 1 disclosed must have specific features. In particular, they are two- or four-stroke engines, with a number of cylinders less than or equal to 6 and with a revolving speed lower than 12000 rpm, preferably lower than 8500 rpm.

There is another limitation relating to the cylinder capacity. Two-stroke internal combustion engines have a cylinder capacity of between 40 and 700 cc, whilst four-stroke internal combustion engines have a cylinder capacity of between 40 and 2200 cc.

Taking into account said limits, hereinafter defining as the characteristic flow rate the atmospheric pressure air intake flow rate with an engine operating at full load, the present invention is applied to engines having a characteristic flow rate which depends on the revolving speed, the cylinder capacity and the number of engine strokes and is defined by the following equation:

Qm < Vm x 3,102 x 10^"6 x CyI / NoS ^" (A) where:

Qm is the engine 2 characteristic air intake flow rate, measured in kg/min;

Vm is the engine 2 revolving speed, measured in rpm; CyI is the engine 2 overall cylinder capacity, measured in cubic centimetres; and

NoS is the number of engine 2 strokes.

Finally, in addition to the upper limit indicated above, the engine 2 characteristic air intake flow rate, applicable to the engine unit 1, preferably also has a lower limit, defined by the equation: Qm > Vm x 1,116 x 10^{"6 χ} CyI / NoS (B)

Therefore, considering the two equations indicated above, the engine 2 characteristic air intake flow rate is preferably within the range:

Vm x 1,116 x 10^"6 x CyI / NoS < Qm < Vm x 3,102 x 10^"6 x Cyl / NoS. Advantageously, the engine 2 may be a controlled ignition engine (and, more particularly, an engine in which ignition of the fuel - comburent mixture is triggered by an electric discharge from the electrodes of a sparkplug, for example in engines operating with the Otto cycle) or a compression ignition engine (and, more particularly, an engine where ignition of the fuel — comburent mixture occurs through a compression process, for example in engines operating with the Diesel cycle).

In the case of compression ignition engines, in accordance with the present invention, the engine revolving speed is limited and is less than 5000 rpm.

Connected to the engine 2 described above, the engine unit 1 comprises a regenerative blower 3 having a compression ratio less than or equal to 1.6.

Moreover, in the range of internal combustion engines defined above, in accordance with the present invention, the regenerative blower 3 must supply an air flow rate which also depends on the engine revolving speed, cylinder capacity and number of strokes, defined by the equation: Qc < (7,125 x 10^'18 x Vm⁴ - 2,114 x lO^"13 x Vm³ + 1,664 x 10^"09 x Vm² +

3,880 x 10^"06 x Vm) x CyI / NoS (C) where:

Qc is the air flow rate supplied by the regenerative blower 3, measured in kg/min. Moreover, the regenerative blower 3 must preferably supply an air flow rate which is lower than that identified above and defined by the equation:

Qc < (6,804 x 10^"18 x Vm⁴ - 1,971 x 10^'13 x Vm³ + 1,526 x 10^"09 x Vm² + 3,224 x 10^"06 x Vm) x CyI / NoS (D)

Finally, in addition to the upper limits indicated above, the air flow rate supplied by the regenerative blower 3, which can be applied to the engine unit 1, preferably also has a lower limit, defined by the equation:

Qc > (-8,560 x 10^"15 x Vm³ + 1,162 * 10^"10 x Vm² + 9,952 x 10^"07 x Vm) x CyI / NoS (E)

Therefore, considering the equations indicated above, the air flow rate supplied by the regenerative blower 3 is preferably within the range:

(-8,560 x 10^"15 x Vm³ + 1,162 x 10^"10 x Vm² + 9,952 x 10^"07 x Vm) x CyI / NoS < Qc < (6,804 x 10^"18 x Vm⁴ - 1,971 x 10^"13 x Vm³ + 1,526 x 10^"09 x Vm² + 3,224 x 10^"06 x Vm) x CyI / NoS.

In accordance with the present invention, the regenerative blower 3 may be driven in various ways. The regenerative blower 3 may be directly keyed on the engine shaft, or it may be connected to the engine shaft by a gear ratio, or it may have its own drive unit and so be driven independently of the engine. Therefore, the regenerative blower 3 may be integral with the engine, if necessary one or more regenerative blower 3 components being shared with the engine or made in parts of the engine, or it may be a separate device.

In accordance with more complex embodiments of the present invention, the engine unit may comprise other components in addition to the engine 2 and the regenerative blower 3.

Advantageously, the engine unit 1 may also comprise an intake filter 14, positioned upstream of the regenerative blower 3 so as to supply filtered air to the regenerative blower 3.

Moreover, the engine unit 1 may comprise a heat exchanger 15, commonly known as an "intercooler", positioned along the engine 2 inlet duct 5, downstream of the regenerative blower 3. The task of the heat exchanger 15 is to keep within acceptable values the temperature of the compressed air which enters the engine 2 combustion chamber 4. The main aim is to guarantee correct compressed air density and to prevent pre-ignition or detonation phenomena which would be favoured by high temperatures.

Moreover, if the heat exchanger 15 is present, the engine unit 1 may also have a secondary duct 16, regulated by a valve 17, for allowing the compressed air to bypass the heat exchanger 15 in predetermined operating conditions.

Advantageously, the engine unit 1 also comprises a control system 18 for regulating the engine 2 and/or regenerative blower 3 operating parameters. Said control system 18 may include several sensors and devices (with mechanical and/or electronic control) designed to guarantee that the air at the engine 2 infeed is in the correct physical state in the various operating conditions.

There are various types of such sensors and devices, of which all or only a part may be present and which in some cases may be integrated in the main control system for the whole engine unit 1. A first example of sensors consists of sensors for controlling the compressed air temperature and sensors for controlling the compressed air pressure. The pressure sensors are preferably positioned upstream and downstream of the regenerative blower 3 and downstream of the element for regulating the engine load (for example, a throttle valve). The temperature sensors are positioned upstream and downstream of the regenerative blower 3.

Another device preferably present in the control system 18 is an overpressure valve 19, designed to control the supercharging pressure, guaranteeing that it remains within the desired limits for each operating condition. Even in said case, any excess air flow is recirculated to the regenerative blower 3 intake or discharged into the atmosphere.

An example of a valve preferably present in the control system 18 is a bypass valve (or a "pop off' valve). It is applied above all in engines in which load regulation is achieved using an element which chokes the flow of compressed air ("quantity regulation"), for example Otto cycle engines with intake throttles. Said valve is designed to prevent the creation of abnormal pressure peaks in the system upstream of the choke element, for example at the moment when it closes rapidly ("gas closing", accelerator release step). Controlled according to the pressure difference upstream and downstream of the choke element, the valve recirculates the excess air upstream of the regenerative blower 3 (bypass valve) or discharges the excess air directly into the atmosphere ("pop off' valve). Finally, the control system 18 may comprise a single-acting valve 20 positioned downstream of the regenerative blower 3. Said single-acting valve allows engine air intake directly from the outside environment and therefore it is designed to guarantee engine operation in the "naturally aspirated" condition in the case of a regenerative blower 3 fault (stop).

There are many fields of application for the engine unit 1 described above.

The engine unit 1 can preferably be applied on land vehicles with any type of transmission and, more particularly, it is very advantageous on vehicles in which the engine transmits the movement by means of a continuously variable transmission, for example in motorcycles and, more particularly, in scooters.

Moreover, said engine may advantageously be applied on ultralight aircraft and, more specifically, aircraft with a propeller final drive.

Finally, there are many other fields for application of such an engine unit 1 : for example, with internal combustion engines operating at a fixed point (such as engines for generating sets or generating plant), with marine engines, with motor pumps and engine-driven compressors, on snowploughs and in tools such as chain saws, welders, mowers and trimmers.

For example, a test carried out in the field is described below.

The engine unit 1 tested comprises an engine 2 for motor vehicles, having the following features:

- four-stroke engine;

- number of cylinders is 1;

- total cylinder capacity of 459 cc;

- maximum power (with intake at atmospheric pressure) equal to 29.4 kW at 7000 rpm;

- maximum torque (with intake at atmospheric pressure) equal to 43 Nm at 6000 rpm;

- electronic injection feed.

The engine unit 1 also comprises a regenerative blower 3 with double annular chamber 9, having an impeller 7 with axial blades (of the type illustrated in Figure 14). The cross-section of said regenerative blower 3 is shown in Figure 16.

The regenerative blower 3 has the following dimensions:

- impeller external diameter De equal to 215 mm;

- width of the blades 8 Sp equal to 30 mm;

- mean diameter of the annular chamber 9 Dt equal to 195 mm; and

- overall cross-section of the annular chamber 9 equal to 1700 mm² (indicated in Figure 16 by the honeycomb area).

The various tests carried out produced the following results:

where:

- test 0: simply aspirated engine 2, without regenerative blower 3;

- test 1 : supercharged engine 2 with regenerative blower 3, with a ratio of the blower revolving speed to the engine revolving speed equal to 1 ; - test 2: supercharged engine 2 with regenerative blower 3, with a ratio of the blower revolving speed to the engine revolving speed equal to 1.175;

- test 3: supercharged engine 2 with regenerative blower 3, with a ratio of the blower revolving speed to the engine revolving speed equal to 1.35; and

- the power developed by the supercharged engine (in test 1, test 2 and test 3) is net of the power absorbed by the regenerative blower 3.

Figures 17 and 18 show two graphs with the results obtained during the tests. Figure 17 shows the power developed by the engine 2, depending on its revolving speed, in the four operating conditions which were test 0 (pr 0), test 1 (pr 1), test 2 (pr 2) and test 3 (pr 3). Figure 18 shows the torque supplied by the engine 2, depending on its revolving speed, in the four operating conditions which were test 0 (pr 0), test 1 (pr 1), test 2 (pr 2) and test 3 (pr 3).

Figure 19 shows a graph with the engine 2 air intake flow rate, according to its revolving speed, where:

- the min curve is the curve formed by the limit value from the equation (B), calculated for the engine 2 tested;

- the max curve is the curve formed by the limit value from the equation (A), calculated for the engine 2 tested;

- the test 0 (pr 0) curve is the operating curve for the engine used for the tests carried out in the field. Figure 20 shows a graph with the flow rate of air supplied by the regenerative blower 3, according to the engine 2 revolving speed, where:

- the min curve is the curve formed by the limit value from the equation (E), calculated for the regenerative blower 3 tested; - the maxl curve is the curve formed by the limit value from the equation

(D), calculated for the regenerative blower 3 tested;

- the max2 curve is the curve formed by the limit value from the equation (C), calculated for the regenerative blower 3 tested;

- the test 1 (pr 1), test 2 (pr 2) and test 3 (pr 3) curves are the curves of the flow rate supplied by the regenerative blowers 3, used for the tests carried out in the field, in the three respective operating conditions.

As shown in the tables indicated above and in the respective graphs, the engine unit 1 disclosed allows an increase in the power (and consequently, the torque) developed by the engine 2. It should be noticed that: in test 1, the supercharged engine shows an increase in the power developed, compared with the simply aspirated engine, which is greater than 20%. In test 2, the supercharged engine shows an increase in the power developed of approximately 30%. In test 3, the supercharged engine shows an increase in the powered developed which is greater than 35%. The engine unit disclosed therefore achieves the preset aims.

Firstly, the engine unit disclosed has optimum supercharger system dimensions and weights for engines with medium — small cylinder capacity.

Secondly, the engine unit disclosed allows a reduction of exhaust emissions and consumption compared with prior art engine units, with the same maximum power achieved.

Moreover, the engine unit disclosed can allow four-stroke engines to be used where currently two-stroke engines have to be used.

Finally, it should be noticed that the present invention is reliable and even the cost linked to implementation of the invention is relatively low.

Claims

1. An engine unit (1) comprising: an internal combustion engine (2) having an inlet duct (5) into at least one combustion chamber (4); the engine (2) having a characteristic air intake flow rate defined by the equation: Qm ≤ Vm x 3,102 x 10^{"6 χ} CyI / NoS where: Qm is the engine (2) characteristic air intake flow rate, measured in kg/min;

Vm is the engine (2) revolving speed in rpm; said revolving speed being less than 12000 rpm; CyI is the engine (2) overall cylinder capacity, in cubic centimetres;

NoS is the number of engine (2) strokes; said number of strokes being equal to two or four; a regenerative blower (3) connected to the engine (2) inlet duct (5), so as to supply compressed air to the engine (2); said regenerative blower (3) supplying an air flow rate defined by the equation

Qc < (7,125 x 10^'18 x Vm⁴ - 2,114 x 10^"13 x Vm³ + 1,664 x 10^{"09 χ} Vm² +

3,880 x 10^"06 x Vm) x CyI / NoS where Qc is the air flow rate supplied by the regenerative blower (3), in kg/min. the engine (2) having a number of cylinders which is less than or equal to six; the engine (2) having a cylinder capacity of between 40 and 2200 cc; and the regenerative blower (3) having a compression ratio which is less than or equal to 1.6.

2. The engine unit (1) according to the foregoing claim, characterised in that the air flow rate supplied by the regenerative blower (3) is within the range defined by the equation Qc < (6,804 x 10^"18 x Vm⁴ - 1,971 x 10^"13 x Vm³ + 1,526 x 10^"09 x Vm² + 3,224 x 10^"06 x Vm) x CyI / NoS.

3. The engine unit (1) according to any of the foregoing claims, characterised in that the air flow rate supplied by the regenerative blower (3) is within the range defined by the equation

Qc > (-8,560 x 10^"15 x Vm³ + 1,162 x 10^'10 x Vm² + 9,952 x 10^"07 x Vm) x CyI / NoS.

4. The engine unit (1) according to any of the foregoing claims, characterised in that the engine (2) characteristic air intake flow rate is within the range defined by the equation

Qm > Vm x 1,116 x 10^"6 x CyI / NoS.

5. The engine unit (1) according to the foregoing claim, characterised in that the engine (2) is a two-stoke engine with a cylinder capacity of between 40 and 700 cc.

6. The engine unit (1) according to any of the foregoing claims, characterised in that the engine (2) has a revolving speed which is less than 8500 rpm.

7. The engine unit (1) according to any of the foregoing claims, characterised in that it also comprises a heat exchanger (15) positioned along the inlet duct (5) in such a way as to limit the temperature of the compressed air entering the combustion chamber (4).

8. The engine unit (1) according to the foregoing claim, characterised in that it also comprises a secondary duct (16), regulated by a valve, for allowing the compressed air to bypass the heat exchanger (15).

9. The engine unit (1) according to any of the foregoing claims, characterised in that it also comprises a control system (18) for regulating the engine (2) and/or regenerative blower (3) operating parameters.

10. The engine unit (1) according to the foregoing claim, characterised in that the control system (18) comprises at least one sensor for controlling the temperature of the compressed air and/or at least one sensor for controlling the pressure of the compressed air; said at least one sensor for controlling the temperature and at least one sensor for controlling the pressure being positioned upstream and/or downstream of the regenerative blower (3 ).

11. The engine unit (1) according to claim 9 or 10, characterised in that the control system (18) also comprises an element for choking the compressed air flow rate, positioned between the regenerative blower (3) and the engine (2) and comprising a bypass valve controlled by the pressure difference upstream and downstream of the choke element, allowing the elimination of excess compressed air.

12. The engine unit (1) according to any of the claims from 9 to 11, characterised in that the control system (18) also comprises an overpressure valve so that the excess compressed air exiting the regenerative blower (3) is discharged into the atmosphere or recirculated to the regenerative blower (3) intake.

13. The engine unit (1) according to any of the claims from 9 to 12, characterised in that the control system (18) also comprises a single-acting valve for engine (2) air intake directly from the outside environment.

14. The engine unit (1) according to any of the foregoing claims, characterised in that it also comprises an intake filter (14) positioned upstream of the regenerative blower (3) in such a way as to supply the regenerative blower (3) with filtered air.

15. The engine unit (1) according to any of the foregoing claims, characterised in that the engine (2) is a controlled ignition engine or a compression ignition engine.

16. The engine unit (1) according to the foregoing claim, characterised in that the compression ignition engine is a diesel engine and the engine revolving speed is less than 5000 rpm.

17. The engine unit (1) according to any of the foregoing claims, characterised in that the regenerative blower (3) is keyed on the engine (2) shaft or the regenerative blower (3) is connected to the engine (2) shaft by a gear ratio or the regenerative blower (3) is driven independently of the engine (2).

18. The engine unit (1) according to any of the foregoing claims, characterised in that the engine (2) operates at a fixed point.

19. A vehicle characterised in that it comprises an engine unit (1) in accordance with any of the foregoing claims.

20. The vehicle according to the foregoing claim, characterised in that the engine unit (1) transmits the movement by means of a continuously variable transmission.

21. The vehicle according to claim 19 or 20, characterised in that it is a motorcycle.

22. The vehicle according to claim 19 or 20, characterised in that it is an ultralight aircraft.