HK1022506B - Method and device for recuperating ambient thermal energy for vehicle equipped with an pollution-free engine with secondary compressed air - Google Patents

Description

Method and device for recovering thermal energy for a vehicle equipped with a pollution-free engine of secondary compressed air

The present invention, the subject of this patent, relates to land vehicles and, in particular, to land vehicles equipped with pollution-free or pollution-reduced engines, operated with secondary compressed air injection with or without separate combustion chambers, and incorporating high-pressure compressed air accumulators.

In the patent application published in WO96/27737, the authors describe a method of pollution reduction for an engine equipped with separate external combustion chambers, operating according to the two-mode principle with two types of energy, using conventional fuels such as gasoline or diesel fuel, on uninhibited roads (operating with a single mode of air/fuel mixture) or at low speed (particularly in cities and suburbs), adding compressed air (or any other non-polluting gas) to the combustion chambers, excluding any other combustion (air-type single-mode operation, i.e. using additional compressed air). In the patent application FR9607714, the authors describe the installation of such engines operating in single mode, with the addition of compressed air on a service vehicle, for example on a city bus.

In such engines, an air/combustion hybrid mode is used to draw an air/fuel mixture into a separate intake and compression chamber and compress the air/fuel mixture within the chamber. This mixture is then conveyed, still under pressure and in constant volume, to a separate combustion chamber and then combusted to increase the temperature and pressure of the mixture. After opening the conversion system connecting the combustion or expansion chamber with the decompression and exhaust chamber, the mixture is decompressed in the latter chamber in order to produce work. Subsequently, the depressurized gas is discharged to the atmosphere through the exhaust pipe.

During operation with air plus secondary compressed air at lower power, which is a particular subject of the invention, the fuel injection system is no longer controlled: in this case, after entering the combustion chamber of the fuel-free compressed air from the intake and compression chambers, mainly after entering the latter, a small amount of secondary compressed air is injected from an external accumulator which stores the air at high pressure (e.g. 200 bar) and at ambient temperature. This small volume of compressed air at ambient temperature will heat up as soon as it comes into contact with the large volume of high temperature air contained in the combustion or expansion chamber and will expand and thereby increase the pressure in the chamber, thereby enabling the work done by the engine to be transferred during decompression.

Such dual-mode or dual-energy engines (air and gasoline, or air and secondary compressed air) can also be modified by eliminating all operations of the engine using conventional fuel, preferably for all vehicles (e.g. in urban areas), in particular urban buses or other service vehicles (taxis, garbage trucks, etc.) with air/secondary compressed air single mode.

The engine will only operate in a single mode with secondary compressed air entering the combustion chamber, which will thus become an expansion chamber. Furthermore, the air taken in by the engine can be filtered and purified via one or more carbon filters or by any other mechanical or chemical process, or via molecular sieves or via other filters, thereby providing a pollution-free engine. The term "air" as used herein also includes "any non-polluting gas".

In such engines, secondary compressed air is injected into a combustion or expansion chamber at an operating pressure which is established as a function of the pressure prevailing in the chamber, and is injected into the combustion or expansion chamber at a pressure which is much higher than the pressure in said chamber, for example 30 bar, in order to cause its transformation. To achieve this, with conventional depressurization systems, a reactive depressurization is carried out which does not absorb heat and thus does not produce a temperature drop, so that depressurized air at ambient temperature (in our example about 30 bar) is injected into the combustion or expansion chamber.

The method of injecting secondary compressed air may also be applied to a conventional 2-stroke or 4-stroke engine, wherein the injected secondary compressed air is brought into the engine combustion chamber at about top dead center of ignition.

The method according to the invention provides a system that enables and increases the available energy. It is characterized by the means used, in particular the compressed air at ambient temperature (for example 20 degrees) in a very high pressure accumulator (for example, of the order of 200 bar) being decompressed before its final use at low pressure (for example 30 bar), the pressure being reduced to a pressure close to that required for its final use, the work done being able to be recovered and used in any known way (mechanical, electrical, hydraulic, or other) in a variable volume system (for example a piston in a cylinder). The work-producing pressure reduction operation has the result that the compressed air is cooled to a very low temperature (e.g., -100 ℃) and its pressure approaches the pressure required for the final use. This compressed air, which has been depressurized to its use pressure and is at a very low temperature, is then passed into a heat exchanger with ambient air to be heated to a temperature close to the ambient temperature and thereby increase its pressure and/or volume by recovering thermal energy from the atmosphere.

The advantages of the method according to the invention are considerable: firstly, work is done during decompression and can be utilized directly by the main shaft of the engine or indirectly, for example by driving mechanical, electrical or other components; second, ambient temperature is used to gain free heat energy, causing the pressure and/or volume of the air to increase, and thereby increasing the operating range.

A person qualified in this field is able to calculate the quantity of air at very high pressure supplied to the decompression system that does work, as well as the characteristics and volume of the latter, in order to obtain, at the end of the decompression operation of this work, the last chosen working pressure and the coldest possible temperature, these values being a function of the conditions of use of the engine. The electronic control system managing these parameters makes the quantity of compressed air utilized and recovered optimal at all times. Persons qualified in this field can also calculate the characteristics and dimensions of the heat exchangers, who can apply all the concepts known in the field without modifying the method of the invention.

It is also possible to use, partly or otherwise, according to the method of the invention, all or part of the low-temperature air that has been depressurized in all the hot zones of the engine, for example in the cylinder and/or cylinder head cooling system or elsewhere.

According to another characteristic of the invention, the work of pressure reduction is used to provide pneumatic assistance to the gas pressurization system in the combustion or expansion chamber.

According to another characteristic of the method, the power generation can be carried out by means of a decompression system that does work, for example by means of a magnetic core moving inside a coil, advantageously replacing the alternator of the vehicle.

According to another characteristic of the method according to the invention, the air/hot air exchanger can be designed to provide air conditioning to the vehicle in summer by the introduction and distribution (in the vehicle) of the heated air which cools as it passes through the radiator and transfers its heat to the depressurized air.

Furthermore, the characteristic features of the invention described above, which work, can be combined without changing the principle; for example, on the one hand, the heating of the depressurized cooled air can be carried out in two steps, with cooling following the atmospheric air, and vice versa; similarly, electrical energy can be recovered at the start of the trip, and then mechanical energy for the auxiliary equipment can be recovered at the end of the trip.

The operation of reducing the pressure of work can also be achieved in two or more operations, for example, a pressure reduction of work at an intermediate pressure (also utilized by all known systems) followed by a reheating in the air/heat air exchanger before a pressure reduction and reheating of further work (utilized by all known systems).

Other objects, advantages and features of the present invention will become apparent upon reading the specification of several particular embodiments thereof which are described with reference to the accompanying drawings.

FIG. 1 is a schematic side elevational view of a pollution-free engine equipped with pneumatic assist devices for controlling a boost piston;

FIG. 2 shows the same apparatus at the beginning of engine decompression;

FIG. 3 shows the same apparatus at the end of engine decompression;

FIG. 4 shows a pneumatic device for generating electrical energy;

FIG. 5 shows a pneumatic device for generating both electrical and mechanical energy;

FIG. 6 shows a schematic side projection of an apparatus for recovering ambient thermal energy for direct use on the main shaft of an engine;

figure 7 schematically illustrates an apparatus using a heat exchanger that can provide air conditioning for a vehicle.

Fig. 1 shows a schematic side projection of a pollution-free engine and its compressed air supply, comprising an intake and compression chamber 1 and a constant volume combustion or expansion chamber 2, on which constant volume combustion or expansion chamber 2 an additional air injector 22 delivering compressed air from a very high pressure accumulator 23, and a decompression and exhaust chamber 4 are mounted. The intake and compression chamber 1 is connected to the combustion or expansion chamber 2 via a conduit 5 whose opening and closing is controlled by a sealing shut-off flap 6. The combustion or expansion chamber 2 is connected to the decompression and exhaust chamber 4 via a pipe or conveying system 7 whose opening and closing is controlled by a sealed shut-off flap 8. The intake and compression chamber 1 is supplied with air through an intake duct 13, the opening of the intake duct 13 is controlled by a valve 14, and a non-polluting carbon filter 24 is installed upstream of the intake duct 13.

The intake and compression chamber 1 operates like a piston compressor device, in which a piston 9 sliding in a cylinder 10 is controlled by a connecting rod 11 and a crankshaft 12. The decompression and exhaust chamber 4 controls a conventional piston engine by means of a piston 15 sliding inside a cylinder 16, thus driving a crankshaft 18 in rotation via a connecting rod 17. The depressurized air is discharged through an exhaust pipe 19, the opening of which is controlled by a valve 20. The rotation of the crankshaft 12 of the intake and compression chambers 1 is controlled by the engine crankshaft 18 of the decompression and exhaust chamber 4 through a mechanical linkage 21.

According to the invention, the combustion chamber 2 is equipped with a supercharger chamber constituted by a cylinder 25, a piston 26 moving inside the cylinder 25; the movement of the piston 26 is controlled by pressure rods 27 and 28. Between the strut and its control cam 29 there is an auxiliary system, the rotation of which control cam 29 is driven by the engine and is in phase with the engine. The auxiliary system comprises a piston 30, a rod and connecting rod system 34 sliding in a cylinder 31 closed at both ends; the piston 30 is connected by a rod 32 to a bearing 33 acting on the control cam 29, and a rod and link system 34 connects the auxiliary system to the pressure rods 27 and 28 controlling the booster piston 26. The piston 30 controls the passage of two sealed chambers 35 and 36 in the cylinder, a decompression and working chamber 35 at the end of the control cam 29, and a back pressure chamber 36 at the end of the strut. A high-pressure air inlet pipe 37 leads to the decompression and work application chamber 35; the opening and closing of the high-pressure air intake pipe 37 is controlled by an electro-valve 38. The exhaust pipe 39 also opens into the decompression and work application chamber 35, and the opening and closing of the exhaust pipe 39 is controlled by an electrovalve 40. The exhaust duct 39 is also connected to an air/hot air exchanger or radiator 41, which air/hot air exchanger or radiator 41 is itself connected via a duct 42 to a storage buffer system 43 having a practically constant end-use pressure. The back pressure chamber 36 is connected to a buffer accumulator 43 via a conduit 44, the buffer accumulator 43 supplying the additional air injector 22 via a conduit 45.

When the engine is operating in the air/secondary compressed air mode (see fig. 1), and when the booster piston 26 is at bottom dead center, the compression piston causes high temperature compressed air to enter the expansion chamber 2; the additional air injector 22 is then switched so that it injects a small amount of air at ambient temperature and at a slightly higher pressure than the expansion chamber 2 into the expansion chamber 2. A first pressure increase can then be observed in the expansion chamber 2. The computer controlled electro-valve 38 opens allowing a small amount of air at ambient temperature at high pressure supplied by the accumulator 23 and then closes at the same time as the cam 29 starts to push the auxiliary piston 30 backwards. The high pressure compressed air that has been admitted into the decompression and work chamber 35 pushes the auxiliary piston 30 backwards, the auxiliary piston 30 itself pushing the booster piston 26 back towards the upper dead centre by means of the rod and link system 34, the pressure rods 27 and 28, to further increase the pressure in the expansion chamber 2.

During the stroke of the auxiliary piston 30, the compressed air in the auxiliary chamber 35 decompresses to perform work and cause a large temperature drop; its pressure at the end of the stroke is approximately equal to the pressure of the air in the back pressure chamber 36. During these operations, the engine piston 15, which controls the decompression chamber 4, reaches the top dead center (see fig. 2), and the sealed shut-off flap 8 is opened to decompress the compressed air in the expansion chamber 2 and to make the engine work. During this decompression, the cam 29 keeps the intensifier piston 26 at top dead center. Because of the compression lever, the force generated by the pressure in the chamber 2 is not transmitted to the cam 29 and the pressures in the auxiliary chamber 35 and the back pressure chamber 36 are approximately equal, no torque is applied to said cam.

As soon as the decompression operation takes place in the decompression and exhaust chamber 4, which supplies engine power (see fig. 3), the sealed shut-off flap 8 is closed again. The rotation of the cam 29 moves the auxiliary piston further and the sealed shut-off flap 8 opens to let another part of the gas enter the combustion and expansion chamber 2; the electrovalve 40 is opened; the auxiliary piston 30 returns to its starting position, pushed by the return spring 46 and by the pressure in the chamber 2, delivering compressed but partially decompressed and low temperature air from the auxiliary chamber 35 to the air/heat air exchanger or radiator 41. With the heat exchanger 41, the air will be heated to near ambient temperature and will increase in volume when returned to the buffer reservoir 43, already recovering a large amount of energy from the atmosphere.

According to a feature of the method of the invention, electrical energy can be supplied to the vehicle using work reduction. An example of a device implementing this method is shown in fig. 4, where you can see a device very similar to the auxiliary device described above, and having many points in common with the auxiliary device described above; it comprises a piston 30, the piston 30 sliding in a cylinder 31 closed at both ends. The piston 30 is integral with the rod 34 and supports a ferrite core 49 passing within a coil 50, the end of the rod being connected to the return spring 46. The piston 30 controls the passage in the cylinder to two sealed chambers 35 and 36: a decompression and working chamber 35 and a back pressure chamber 36 at the end of the strut 34. The high-pressure air inlet pipe 57 leads to the decompression and working chamber 35; the opening and closing of the high-pressure air intake pipe 57 is controlled by the electro-valve 38. The exhaust pipe 39 also opens into the decompression and work application chamber 35, and the opening and closing of the exhaust pipe 39 is controlled by an electrovalve 40. The exhaust pipe 39 is also connected to an air/hot air exchanger or radiator 41, which air/hot air exchanger or radiator 41 is itself piped to a storage buffer accumulator 43 having a virtually constant end-use pressure. The back pressure chamber 36 is connected to a buffer accumulator 43 via a pipe 44, the buffer accumulator 43 being fed to the additional air injector 22 via a pipe 45.

According to the method of the invention, during the operation of the engine in compressed air mode, as the amount of compressed air consumed by the additional air injector 22 varies, the electrovalve 38 is opened and then the electrovalve 38 is closed to allow a certain amount of high-pressure compressed air to enter the chamber 35. The piston 30 moves by the urging of the pressure differential between the chambers 35 and 36, compressing the spring 46 and causing the rod 34 to cause the ferrite core 49 to move within the coil 50, thereby generating an electrical current. The temperature is reduced by decompression (work) of the high pressure compressed air load at ambient temperature. When the pressure, or more precisely the forces between the two chambers, reach equilibrium, the electrovalve 40 is opened and the piston 30 and the ferrite core 49 are returned to their starting positions by the thrust action of the return spring 46, delivering the compressed, but partially decompressed and very cold air contained in the decompression chamber 35 to the air/hot air exchanger or radiator 41. With the heat exchanger 41, the air will be heated to near ambient temperature and thus increase in volume; this air enters the buffer reservoir 43 where a large amount of energy has been recovered from the atmosphere.

According to a feature of the invention, it is also possible to advantageously combine the two devices described previously: the pressure is highest just at the start of the piston 30 stroke, and the force required to operate the plunger is small. Such a combined device is illustrated in fig. 5, where you can see that on the control rod 34 between the auxiliary system and the strut as shown in fig. 1 to 3 there is a ferrite core 49 sliding inside a copper wire coil 50, similar to that shown in fig. 4. During operation, it is therefore possible to recover electrical energy at the starting point of the stroke in the coil 50 provided for this purpose and then for operation in the manner described in fig. 1 to 3.

In accordance with a key feature of the invention, fig. 6 shows another device for applying and carrying out the method of the invention, in which the pressure reduction is used to produce work, which can be directly utilized at the main shaft of the engine, where both the connecting rod arrangement 53 and the operating piston 54 are directly connected to the main shaft 18 of the engine. The piston 54 slides in a cylinder closed at one end 55 thereof and controls the passage to the working chamber 35: first, a high-pressure intake pipe 37 whose opening and closing is controlled by an electrovalve 38 is opened into the working chamber 35; the exhaust duct 39, connected to the air/hot air exchanger or radiator 41, is then opened into the working chamber 35, the air/hot air exchanger or radiator 41 itself being connected by a duct 42 to a storage buffer system with a practically constant final use pressure. During operation, when the working piston 54 is at its upper dead point, the electrovalve is opened and then closed to introduce compressed air at very high pressure; this air is then depressurized as piston 54 is pushed toward its bottom dead center and drives engine crankshaft 18 via the connecting rod. Then, during the upward stroke of the piston 54, the exhaust valve 40 is opened and the compressed air (which has been partially decompressed and has a very low temperature) in the working chamber is forced into the air/air heat exchanger or radiator 41. Thus, the air is heated to a temperature close to ambient temperature and increases in volume when travelling to the buffer accumulator 43, already recovering a large amount of energy from the atmosphere.

Fig. 7 is a perspective view of an air/hot air exchanger or radiator 41 as described in the previous figures, each device implementing the method of the invention to be described below being equipped by itself with an air/hot air exchanger or radiator 41 to send out very low temperature air through a duct 39 and to condition the vehicle by means of an extraction duct 42 carrying away the heated air used last; the atmosphere intended for reheating is collected by a manifold 58 and blown through the radiator by a fan 56. By transferring its heat to the compressed air in the radiator, the atmospheric air cools and collects in the duct 59, the movable shut-off flap 57 on the duct 59 allowing to direct all the part of said air towards the passenger compartment of the vehicle, to provide air conditioning according to the degree of opening of said shut-off flap. The flow of refrigerated air may be adjusted in any way known in the art, such as storage on a radiator, a shut-off flap, the addition of hot air, etc., without altering the principles of the features of the invention. The system may be used in combination with other devices described above without altering the principles of the invention described above.

Claims (11)

1. Method for recovering environmental thermal energy for an engine or a vehicle equipped with a pollution-free or pollution-reduced engine, which is operated by injecting additional air into a combustion or expansion chamber and which has a high-pressure compressed air storage system, characterized in that, before the final use of the compressed air at a lower pressure, the compressed air in the high-pressure accumulator is decompressed in a variable-volume system, such as a piston in a cylinder, to a pressure close to the desired pressure for the final use, thereby performing work which has the result of cooling the partially decompressed compressed air to a low temperature; this compressed air, which has been partially decompressed to its use pressure, is conveyed to a heat exchanger to heat the air and change its pressure and/or volume by recovering a large amount of thermal energy.

2. The method of claim 1, wherein the low temperature partially depressurized compressed air is passed to a heat exchanger having ambient temperature ambient air to be reheated to a temperature approximately equal to said ambient temperature and thereby increase in temperature and/or volume thereof in a process in which a substantial amount of thermal energy has been recovered from the atmosphere.

3. A method according to claim 1, wherein all or part of the very low temperature reduced pressure air is heated in the hot zone of the engine, thereby acting as a supplementary device to the engine cooling system, whether or not in combination with the passage through the heat exchanger.

4. A method according to claim 2, wherein all or part of the very low temperature reduced pressure air is heated in the hot zone of the engine, thereby acting as a supplementary device to the engine cooling system, whether or not in combination with the passage through the heat exchanger.

5. Use of the method according to claims 1 to 4, characterized in that the work done during the decompression in the variable volume system is recovered and utilized by a mechanical, electrical, pneumatic or hydraulic system to supplement the engine energy.

6. Use of a method according to claim 2, characterised in that the vehicle is air-conditioned by means of ambient air which is passed through an air/heat exchanger and is thus cooled.

7. Apparatus for applying the method of the invention as defined in claim 5, wherein said variable volume system comprises:

a piston (30) provided with a control and/or movement transmission rod (32, 34);

a cylinder (31) closed at both ends and in which a piston (30) slides;

the pressure reducing and working chamber (35) is positioned at one end of the cylinder (31), and a high-pressure air inlet pipe (37) and an exhaust pipe (39) are respectively connected with the pressure reducing and working chamber (35);

electric control valves (38) and (40) respectively positioned in the air inlet pipe (37) and the air outlet pipe (39) and used for controlling the opening and closing of the air inlet pipe and the air outlet pipe;

a heat exchanger (41) connected to a valve outlet duct (39) with an electronic control (40) for controlling the admission of the compressed air at reduced pressure into the heat exchanger (41);

and an accumulator (43) having an inlet end connected to the heat exchanger (41) through a pipe (42), an outlet end connected to the back pressure chamber (36) through a pipe (44), and a secondary compressed air injector (22) through a pipe (45).

8. An apparatus for carrying out the method of the invention as claimed in claim 5, further comprising:

a cylinder-piston system (25, 26), the piston (26) being connected to said piston (30) by means of pressure rods (27, 28), a control rod (34);

a combustion or expansion chamber (2) to which the associated cylinder-piston system (25, 26) is fitted with a secondary compressed air injector (22), the piston (30) pushing the piston (25) towards bottom dead center by means of a pressure rod (27, 28), a control rod (34) increasing the pressure in the combustion or expansion chamber (2).

9. The apparatus for performing the method of claim 5, wherein the means for providing electrical energy using work from the pressure reduction system comprises:

-a ferrite core (49) fixed to said control rod (34);

a coil (50) within which the ferrite core (49) is movable; and

a spring (46) attached to an opposite end of the control rod (34) from the piston (30); the piston (30) can be returned.

10. The device for implementing the method of the invention as claimed in claims 1 to 4, characterized in that said variable volume system comprises:

a cylinder-piston system (55, 54), one end of the cylinder (55) being closed;

the connecting rod (53) and the engine crankshaft (18), wherein the engine crankshaft (18) is connected with the piston (54) through the connecting rod (53);

one end of the pressure accumulator (43) is connected with the heat exchanger (41) through a pipeline (42), and the other end of the pressure accumulator (43) is connected with the secondary compressed air ejector (22) to control the inlet of high-pressure air and the discharge of decompressed low-temperature air;

a high-pressure air inlet pipe (37) and an electric valve (38) which are connected with the cylinder (55) and the pressure accumulator (43);

an exhaust pipe (39) and an electric valve (40) connecting the cylinder (55) and the heat exchanger (41).

11. An apparatus for carrying out the method of the invention as claimed in claim 6, characterized in that it comprises:

a fan (56) and a manifold (58) to direct ambient air and blow it through the heat exchanger (41);

a duct (59) and a movable shutoff flap (57) control cooled air entering a passenger compartment of the vehicle.