Injection device for a compressed-air engine, compressed-air engine provided with such a device and hybrid drive train comprising such an engine

Abstract

The invention relates to a mechanical device for injecting compressed air for a compressed-air engine with pistons having optimised consumption and power. The device comprises a compressed-air intake valve (S) comprising a first part (20) and a second part (30) mounted so as to slide relative to one another in the direction of movement of the piston, the movement of the first part (20) being mechanically controlled by the piston, the injection device also comprising a means (60) for temporarily retaining the second part (30) relative to the first part (20) so as to impose a desynchronized movement between the second part (30) of the valve and the piston (1).

Description

Injection device for compressed air engine, compressed air engine equipped with such a device and hybrid drive train comprising such an engine.

[0001] The present invention relates to a compressed air engine with low air consumption, and a compressed air injection cycle in this engine, designed according to the known principle of so-called "two-stroke" or "four-stroke" internal combustion engines of "diesel" engines.

[0002] It also relates to an injection device for such an engine, a cylinder head incorporating this injection device and a hybrid powertrain comprising such an engine.

[0003] The invention finds a particularly important, although not exclusive, application in the field of motorization of land vehicles (such as cars or utility vehicles) or marine vehicles (such as boats), but also for motorization used in industry or for craft activities such as, for example, generator sets.

[0004] A particularly interesting application of the motor according to the present invention, given solely by way of non-limiting example, is found in the integration of this motor in a drive chain comprising an electric generator engaged with the shaft of the motor, the generator being connected to an electric motor.

[0005] In fact, there are many powertrain solutions based on thermal engines, electric motors or a combination of the two (called hybrid powertrains).

[0006] So-called "thermal" vehicles require the use of polluting fossil fuels, which has led authorities in many countries to favor other, less polluting types of powertrains. Their main advantage comes from their autonomy and the speed at which the fuel tank can be refilled.

[0007] So-called "electric" vehicles have a drive train composed of a power battery capable of supplying the electric motor(s) capable of driving a transmission connected to a moving part (the wheels of a car or the propeller of a boat, for example).

[0008] A power battery is distinguished from a vehicle's starter battery by its power, capacity, and ability to drive a vehicle's wheels or propeller.

[0009] The power batteries used in electric vehicles are currently lithium-ion batteries, because only this type of battery provides the power and autonomy suitable for this use.

[0010] The major disadvantage of the electric drive train lies precisely in the battery.

[0011] Indeed, its manufacture and end of life are ecologically problematic: lithium reserves are theoretically insufficient to equip all the vehicles in the world, and the recycling process is currently unknown.

[0012] In addition, lithium-ion batteries have a definite tendency to heat up during charging, or even during use, and many incidents have been recorded in which batteries have caught fire due to this overheating.

[0013] Hybrid powertrains have also been proposed, in which a thermal engine either assists the electric motor, recharges the power battery, or both.

[0014] These hybrid vehicles, however, have all the drawbacks of both technologies: pollution, risk of fire, complex or even impossible recycling, etc.

[0015] There is therefore a need to offer an engine and a drive train that reduce the pollution generated and operating risks.

[0016] A classic two-stroke air-powered piston engine is already known, and illustrated in.

[0017] The engine comprises a cylinder block A comprising at least one piston 1 connected to a drive shaft 2 by means of a connecting rod 3 rotatably attached to a counterweight 4. The piston 1 is mounted to move in translation (arrow F1) in a compression / extension chamber 5, the upper end of which is closed by a cylinder head B. In the lower part, the chamber 5 comprises an opening 6 for admitting external air (arrow F2), as well as a channel 7 for conducting external air (arrows F3 and F4) opening into the chamber 5 above the piston 1 when the latter is at bottom dead center. The chamber 5 also comprises an exhaust outlet 12 for discharging the expanded compressed air when the piston descends and is located near its bottom dead center.

[0018] In the upper part, hermetically closing the chamber 5, the cylinder head B comprises at least one compressed air intake valve 8 from (arrow F5) a high-pressure compressed air reserve 9 via a pressure reducer 10 (aimed at reducing the air pressure from 300 bars coming from the reserve to a pressure of 30 to 50 bars at the outlet towards the compressed air intake chamber 11 located upstream of the intake valve 8). The compressed air intake valve 8 comprises a valve stem 8a, movable in translation (arrow F6) relative to the cylinder head B, and provided with a valve head 8b carrying a contact surface 8c with a valve seat 8d located in the cylinder head B.

[0019] The valve head 8b protrudes into the chamber 5 by a determined length, so that the piston 1 pushes the valve stem upwards. However, for the injected compressed air volume to be sufficient to generate the required engine work, this opening must last a sufficiently long time. Consequently, the valve head must protrude into the chamber by a significant length which, in turn, controls the opening of the valve well before the top dead center of the piston.

[0020] Furthermore, in this type of engine, a volume of outside air, taken at atmospheric pressure when the piston is in the low position (bottom dead center or BDC), is compressed by the piston in the piston chamber when the latter rises. The compressed air heats the walls of the chamber. It is then possible to inject compressed air from the compressed air reserve into this heated chamber via the intake valve. The compressed air then expands due to the pressure difference and the high temperature of the chamber, which forcibly pushes the piston downwards, generating mechanical work and allowing the expanded air to be expelled. Then the cycle resumes: intake of outside air, compression of the air in the chamber by the rising piston and heating of the chamber, injection of compressed air into the chamber, generation of mechanical work, expulsion of the air to the outside.

[0021] By heating chamber 5, this device therefore improves the efficiency of the compressed air by promoting greater and faster expansion, but it still has many defects, particularly when the piston rises.

[0022] Indeed, a first problem lies in the fact that depending on the adiabatic compression ratio of the air, the temperature of the cylinder, when the piston is in the upper position, can exceed 600 degrees Celsius and the pressure several tens of bars. The external air thus compressed therefore opposes the rise of the piston in the last millimeters, so that the engine loses power.

[0023] Furthermore, compressed air must always be injected at a pressure higher than that of the compressed air in the piston chamber, to allow for expansion and engine work. The compression ratio of the air compressed by the piston, coming from outside, therefore defines the minimum pressure to be injected into the cylinder, which therefore does not allow for fine control, and therefore optimization, of air consumption.

[0024] Thus, a significant part of the piston's rise is opposed by the thrust of the valve and by the pressure of the ambient air compressed by the piston.

[0025] This is all the more true since a compressed air engine differs from a combustion engine in particular by a much larger volume of injected air than the volume of injected fuel, to generate comparable engine work. It is therefore necessary to play on the air passage section, but also on the duration of opening of the intake valve in order to ensure the injection of a sufficient volume of compressed air compatible with the desired use.

[0026] For comparison, with a comparable opening time, the diameter of diesel injectors is 0.1 millimeters, while the opening of the passage for compressed air is about 7 millimeters, i.e. seventy times larger.

[0027] For this reason, in the prior art, it is necessary to start the air injection before the piston has reached its top dead center.

[0028] We therefore understand that this compressed air added to the external air already compressed by the piston very strongly opposes the end of the piston's rise, which causes a loss of engine power.

[0029] A second problem is that the valve head is struck by the piston at a time when it is at a very high speed since this happens well before the top dead center of the piston, which leads to rapid fatigue of the parts and therefore unsatisfactory reliability of the engine.

[0030] Document FR3115313 attempts to solve this second problem. In particular, it describes a modified compressed air injection valve, in which the valve is integral with the piston (no impact of the parts) and is provided with a groove of a determined length to allow the air to pass sequentially.

[0031] However, this groove must be of significant length to allow the injection of sufficient compressed air to generate the required engine work. Consequently, air begins to enter the chamber well before the piston has reached top dead center. This does not solve, or even amplifies, the first problem.

[0032] This is why it has already been proposed to add an ejection valve allowing the compressed air from the piston to escape just before injecting compressed air from the reserve into the chamber, in order to reduce the pressure in the chamber. It has also been proposed to circulate this ejected air in a volume surrounding the chamber to further heat the chamber, but this arrangement makes the engine design very complex, without bringing a notable improvement. In addition, the opening of the intake and ejection valves is controlled by two camshafts, as in thermal engines, which makes the design complex and increases the weight of the assembly.

[0033] The objective of the present invention is therefore to propose a mechanical solution making it possible to improve the reliability of the engine.

[0034] Another objective of the present invention is to propose a compressed air engine having lower consumption for equal generated motor power, so as to increase the autonomy and efficiency of the device equipped with said engine: vehicle or generator set.

[0035] In other words, one of the objectives of the invention is to increase the efficiency of the engine, that is to say to increase the driving power for an identical quantity of injected air, or to reduce the quantity of injected air for an identical driving power.

[0036] However, the inventor had the idea that an injection which would take place closer to top dead center would make it possible to reduce the negative work consumed by the piston rising.

[0037] The idea behind the invention is to provide delayed air injection, while ensuring a sufficient volume of injected air to obtain a driving power compatible with the desired use. This will improve engine efficiency.

[0038] The present invention provides a mechanical type solution, in the sense that it does not require any sensor or electronic control of the opening of the air intake valve. This solution has the advantages of non-existent electrical consumption, the absence of a sensor and therefore high reliability.

[0039] An engine covered by the invention is similar to that illustrated in, but is distinguished therefrom by the particular design of the compressed air injection device.

[0040] Thus, the invention provides a mechanical compressed air injection device designed to equip a compressed air engine comprising at least one piston intended to move in a chamber, said device comprising at least one compressed air intake valve, each valve being adapted to operate with a piston of the engine when the device is in the position of use in the engine, this valve comprising a first part and a second part mounted to slide in the direction of movement of the piston, the movement of the first part being, in operation, mechanically controlled by the piston, characterized in that the first part and the second part are mounted to slide relative to each other in the direction of movement of the piston and in that the injection device further comprises, for each valve, a means for temporarily retaining the second part relative to the first part so as to impose, in operation,a delayed, i.e. out-of-synchronization, movement between the second part of the valve and the piston.

[0041] More specifically, the first part of the valve of the compressed air injection device according to the invention has its movement controlled solely by the piston, while the second part, which surrounds the first part so that the first part can slide inside the second part, has its movement controlled by the piston and by the temporary retaining means.

[0042] In particular and / or advantageous embodiments, this device may include one and / or other of the following characteristics:

[0043] The first part comprises a rod secured to the piston, and the second part is constituted by a sleeve in which the rod of the first part slides, the rod of the first part and the sleeve of the second part being intended to be slidably mounted in a chamber of the cylinder head of the engine, and the length of the sleeve being less than the length of the rod.

[0044] The temporary retaining means consists of at least one permanent magnet intended to be placed near the bottom of the chamber.

[0045] The second part is made at least partially of a magnetic material.

[0046] The rod includes, at its end opposite the piston, a thrust washer.

[0047] The invention also relates to a compressed air engine cylinder head comprising an injection device according to the invention, the cylinder head being advantageously shaped to fit an existing compressed air engine or designed for this engine.

[0048] This cylinder head has a valve orifice, hereinafter called "valve seat", the cross-section of which is complementary to the cross-section of the second part to ensure a seal against compressed air when the second part is engaged in the orifice. A seal is advantageously provided between the orifice and the second part to reinforce the seal.

[0049] The invention also relates to a compressed air engine incorporating a cylinder head according to the invention.

[0050] The invention also relates to a hybrid powertrain intended to equip a vehicle comprising a high-pressure compressed air reservoir connected to a compressed air piston engine according to the invention engaged with an electric generator for generating electricity when it is driven by the compressed air piston engine, the electric generator being connected to at least one electric motor connected to a transmission engaged with a moving member of the vehicle.

[0051] Preferably, the generator and said at least one electric motor are connected via an electrical relay reserve with a capacity of between 0.2 and 2.2 Watt-hours per kilo of vehicle to be equipped (Wh / kg of vehicle).

[0052] Preferably, the drive chain further comprises an accelerator control movable between a stop position and a maximum acceleration position and connected to an electronic control circuit comprising a controller programmed to power the electric motor from the relay electrical reserve as a function of a signal captured by at least one sensor fitted to the vehicle.

[0053] The invention finally relates to a generator set comprising or intended to be associated with a high-pressure compressed air tank. The generator set comprises a compressed air piston engine according to the invention engaged with an electric generator to generate electricity when driven by the compressed air piston engine.

[0054] Thus, the invention relates to a compressed air engine comprising:– an engine block comprising at least one cylinder having a chamber and a piston, said piston being mounted to move in translation in said chamber, and– a cylinder head associated with the engine block and capable of closing the or each chamber, the cylinder head comprising a mechanical compressed air injection device comprising at least one compressed air intake valve (S) opening into the or each chamber, such that each valve is adapted to operate with a piston of the engine when the device is in the position of use in the engine, this valve comprising a first part and a second part mounted to slide in the direction of movement of the piston, the movement of the first part being, in operation, mechanically controlled by the piston,characterized in that the first part and the second part are mounted to slide relative to each other in the direction of movement of the piston and in that the injection device also comprises, for each valve, a means for temporarily retaining the second part relative to the first part so as to impose, in operation, a desynchronized movement between the second part of the valve and the piston.,

[0055] In particular and / or advantageous modes, this engine may include one and / or other of the following characteristics:

[0056] The movement of the first part of the valve is controlled solely by the piston, while the second part surrounds the first part so that the first part can slide inside the second part and has its movement controlled by the piston and by the temporary retaining means.

[0057] The first part comprises a rod secured to the piston, and the second part is constituted by a sleeve in which the rod of the first part slides, the rod of the first part and the sleeve of the second part being intended to be slidably mounted in a chamber of the cylinder head of the engine, and the length of the sleeve being less than the length of the rod.

[0058] The temporary retaining means consists of at least one permanent magnet intended to be placed near the bottom of the chamber.

[0059] The second part is made at least partially of a magnetic material.

[0060] The rod includes, at its end opposite the piston, a thrust washer.

[0061] The invention also relates to a cylinder head intended to equip a compressed air engine according to the invention, provided with an injection device according to the invention.

[0062] The invention also relates to an injection device intended to equip a compressed air engine and / or a cylinder head according to the invention, this device comprising the characteristics previously described.

[0063] Thus, the injection device according to the invention comprises as many valves as pistons present in the engine equipped with the device and as many retaining means as valves.

[0064] The invention will be better understood and other aims, advantages and characteristics thereof will appear more clearly on reading the description which follows and which is made with reference to the appended drawings, in which:

[0065] is a sectional view of a conventional two-stroke air-powered engine which has been previously described;

[0066] is a sectional view of an embodiment of an injection device according to the invention, the device being in the closed position;

[0067] represents six sectional views of the injection device illustrated in, representing different stages 3a to 3f of the operating cycle of the engine and the injection device;

[0068] is a Clapeyron diagram of a conventional compressed air engine, shown in; and

[0069] is a Clapeyron diagram of a compressed air engine according to the invention, illustrated in.

[0070] Elements common to the different figures are designated by the same references.

[0071] It represents a compressed air engine with valve S in the closed position, while piston 1 is between top dead center and bottom dead center. Reference A designates the engine's cylinder block, reference B its cylinder head, and reference 5 the compression / extension chamber of the engine block or cylinder block in which piston 1 is mounted in translation.

[0072] The first part 20 of the valve is integral with the piston 1. It can be attached and welded or glued to the piston, or it can be an integral part of the piston.

[0073] This first part 20 comprises a rod 21 of diameter smaller than the diameter of the opening of the valve seat 50 located in the cylinder head B. A first end of the rod is integral with the piston 1 and a second end of the rod is provided with a terminal thrust washer 22 of diameter just smaller than a chamber 40 in which the valve S slides. This chamber 40 is formed in the cylinder head and has a bottom 41.

[0074] As described below, the washer 22 has several functions. It serves as a means of guiding the rod 21 in the chamber 40 of the cylinder head B, the diameter of the rod 21 being smaller than that of the chamber 40. It also serves as a stop for the second part 30 and allows it to be driven towards the piston during an operating phase.

[0075] The rod 21 has a determined length L1, taken between its end secured to the piston and the terminal thrust washer 22.

[0076] The second part 30 of the valve is constituted by a sleeve surrounding the rod 21 of the first part, and of length L2 less than the length L1, this sleeve being of cylindrical shape. The sleeve 30 is therefore mounted sliding around the rod 21, between two stops: the piston 1 on the one hand, and the washer 22 on the other hand.

[0077] In the position illustrated in , the sleeve 30 bears against the upper face 1a of the piston by gravity.

[0078] As will be explained later, the difference between the lengths L1 and L2 determines the section and the opening time of the compressed air passage.

[0079] Finally, the means for temporarily retaining the second part 30 relative to the first part 20 is constituted by at least one, preferably at least two, permanent magnets 60, located in the yoke B, close to the bottom 41 of the chamber 40. The second part is chosen from magnetic material or comprises a magnetic part.

[0080] The sleeve 30 has an outside diameter substantially equal to (i.e. immediately smaller than) the diameter of the opening of the valve seat 50 located in the cylinder head B, so that, as shown in , when the sleeve 30 passes through the opening of the valve seat 50, compressed air cannot be injected into the chamber 5 of the piston.

[0081] The valve seat 50 has a cylindrical section, complementary to that of the sleeve.

[0082] The kinetics are explained in Figures 3a to 3f of the, and the relative motions of the different parts will thus appear more clearly.

[0083] Figure 3a illustrates, like the, the valve S in the closed position at the start of the operating cycle.

[0084] In this first step, both the stem 21 of the first part 20 and the second part 30 of the valve S are present in the opening of the seat 50 of the valve. This is hermetically sealed and prevents the entry of compressed air into the chamber 5.

[0085] Piston 1 rises in chamber 5 (according to arrow F7) while the ambient air contained in the chamber is compressed and rises in temperature.

[0086] Figure 3b illustrates the next step in which piston 1 reaches top dead center (TDC).

[0087] The speed of the piston is then zero and the sleeve 30, free to slide, is then propelled towards the washer 22 (arrow F8; figure 3c), in the same direction of movement as the piston.

[0088] This movement is caused by the kinetic energy of the sleeve 30 and by the magnetic attraction of the permanent magnets 60. The sleeve 30 slides on the rod 21.

[0089] This movement continues until the sleeve 30 comes into contact with the washer 22, as illustrated in Figure 3c.

[0090] The upward movement of the sleeve 30 causes the valve seat to open, allowing compressed air to enter the chamber 5 through the orifice in the valve seat 50. As a result, the compressed air expands, pushing the piston 1 downwards.

[0091] Figure 3d illustrates the start of the downward translational movement of piston 1 (arrow F9).

[0092] The presence of the magnets 60 makes it possible to retain the sleeve 30 which does not fall immediately by gravity even when the piston begins to descend and is driven by the washer 22. As a result, the valve seat 50 remains open and the compressed air can continue to pass into the chamber 5 even after the piston has begun to descend (arrow F9).

[0093] Figure 3e shows that the washer 22 continues to push the sleeve 30 downwards and that the latter begins to close the valve seat 50.

[0094] Figure 3f shows that, when the magnets no longer exert sufficient attractive force on the sleeve 30 to retain it, the latter slides downwards on the rod 21 (arrow F10), due to the movement of the piston imparted to the sleeve 30 by the washer 22, and gravity. The sleeve 30 then comes to bear on the upper face 1a of the piston 1, closing the valve seat 50 and preventing the arrival of compressed air in the chamber 5.

[0095] The invention is not limited to the embodiment described and the magnets could be replaced by a purely mechanical temporary retention system.

[0096] The above description shows that by sliding in the second part 30, the rod 21 ensures the vertical guidance of the valve and it is, from a functional point of view, similar to a conventional valve rod.

[0097] Furthermore, the sleeve 30 acts as a shutter by cooperating with the valve seat 50 in the closed position of the valve and is therefore, from a functional point of view, similar to a valve head.

[0098] It is understood that the permanent magnets 60 retain the second part 30 when the piston begins to descend (F9) and that the terminal thrust washer 22 drives it downwards. This makes it possible to keep the air passage to the piston chamber open and to obtain the closure of the passage only in a delayed manner, that is to say desynchronized, with respect to the piston, and therefore with respect to a solution where there would be no magnets.

[0099] In other words, this device allows to obtain an air passage which opens and closes automatically and according to a kinetics different from the kinetics of the piston thanks to the delay effect caused by the magnets, the movement of the second part being desynchronized with respect to that of the piston.

[0100] The sliding of the second part 30 along the first part 20 and its holding in the high position by the magnets 60 acts as if the passage between the cylinder head and the first part had a variable section and asynchronously with the piston, between a zero section where the second part 30 closes the passage, and a maximum section as long as the second part 30 is held against the terminal thrust washer 22 by the magnets 60.

[0101] This therefore differs fundamentally from the solution of patent FR3115313 where the rhythm of opening of the passage is synchronous with the movement of the piston, since the passage groove has a constant length and is carried by the rod.

[0102] By choosing the respective lengths L1 and L2 of the first and second parts, we ensure the injection of an optimal volume of air, at an optimal position of the piston.

[0103] Once the L1-L2 dimensions are chosen, the injected volume remains constant.

[0104] Generally speaking, the different embodiments of the invention make it possible to generate 15 to 25% more mechanical work by only injecting air when the piston is closest to its top dead center.

[0105] Thus, figures 4 and 5 illustrate the Clapeyron diagrams of a conventional device and of a device according to the invention.

[0106] More precisely, the illustrates the Clapeyron diagram of a classic piston engine, shown in. In this figure as in the, the variable of Volume, classically used in a Clapeyron diagram, is replaced by the Height of the chamber between the cylinder head and the piston, since the section of the piston chamber is constant.

[0107] This diagram reads as follows:

[0108] At point 1, the piston is in the bottom position (BDC), so the chamber height is at its maximum. Outside air is admitted into the chamber at atmospheric pressure.

[0109] As the piston moves up, the height of the chamber decreases and the pressure of the air in the chamber increases to reach point 2.

[0110] At this height, the piston meets the valve head, lifts it, and opens the valve. The injection of compressed air immediately increases the pressure to reach point 3. The piston continues to rise to top dead center, against the air pressure, so that the system consumes work from point 3 to point 3*. Then the piston begins to descend again, until the valve closes (passing from point 3* to point 3), generating work that compensates for the work consumed by the piston to reach its top dead center (passing from point 3 to point 3*). This compensation of work consumed / work created is symbolized in the figure by a horizontal line between point 3 and point 3* which illustrates zero work.

[0111] From point 3, the compressed air continues to expand, pushing back the piston and generating work (area under the curve corresponding to the integral of the curve P=f(H)). The height of the chamber therefore increases again and the pressure inside the chamber drops until the air escapes, at point 4, through the exhaust outlet 12 of the chamber (see).

[0112] The pressure therefore immediately decreases to atmospheric pressure (point 5). The piston drops further to its bottom dead center (point 1 of the diagram), allowing the admission of outside air for a new cycle towards point 2.

[0113] Illustrates the Clapeyron diagram of an engine with desynchronized mechanical injection according to the invention, illustrated in. This diagram reads as follows:

[0114] At point 1a, the piston is in the bottom position (BDC), so the chamber height is at its maximum. Outside air is admitted into the chamber at atmospheric pressure.

[0115] When the piston rises, the height of the chamber decreases and the pressure of the air in the chamber increases. As it rises, the first part 20 secured to the piston rises. In addition, the second part 30, resting against the piston, is pushed upwards by the latter, which does not open the valve.

[0116] The piston therefore continues to rise until the second part 30 is attracted upwards by the permanent magnets, thus opening the passage for air at point 2a of the diagram.

[0117] At this height, the piston is closest to its top dead center and the valve is open. The height of point 2a is therefore greater than the height of point 2 in the diagram of the conventional device. The injection of compressed air immediately increases the pressure to reach point 3a*.

[0118] Then the piston begins to descend again until the second part escapes the attraction of the permanent magnets and descends again, closing the valve (point 3a). While the height of the piston in the chamber decreases, the passage from point 3a* to point 3a is done at constant compressed air pressure and equal to the compressed air pressure since the compressed air passage remains open thanks to the holding of the second part by the magnets, which generates mechanical work by pushing the piston back.

[0119] When the valve closes (point 3a), the compressed air expands, continuing to push the piston back and generate work. The height of the chamber therefore increases again and the pressure inside the chamber drops until the air escapes, at point 4a, through the chamber's exhaust outlet (identical to outlet 12 of the).

[0120] The pressure therefore immediately decreases to atmospheric pressure (point 5a). The piston drops further to its bottom dead center (point 1 of the diagram), allowing the admission of outside air for a new cycle towards point 2.

[0121] On the, the white surface W1 represents the common work of the conventional device and the desynchronized injection device according to the invention. The hatched surface W3 represents the additional work generated by the device according to the invention of the.

[0122] In the case of an injection system according to the invention, it is noted that the total work, W2=W1+W3, generated by a device according to the invention is 15 to 25% greater than the work W1 generated by a conventional device.

[0123] By shifting the start of the intake towards TDC (so we align points 2a and 3a*), we increase the work / power recoverable at the engine output, because the engine will work as a producer at constant pressure from TDC until the intake valve closes (point 3a* towards point 3a) before expanding the air from the intake valve closes (point 3a) until it passes the exhaust port (point 4a).

[0124] The whole process and device can be used for exhaust in a conventional cylinder.

[0125] The invention also relates to a cylinder head integrating an injection device as described as well as a compressed air engine integrating such a cylinder head and therefore an injection device as described.

[0126] A particularly interesting application of the engine according to the invention is to integrate it into a hybrid powertrain intended to equip a vehicle comprising a high-pressure compressed air tank connected to a compressed air piston engine according to the invention engaged with an electric generator to generate electricity when it is driven by the air piston engine.

[0127] The vehicle also includes at least one electric motor connected to a transmission engaged with a moving member of the vehicle.

[0128] The generator and said at least one electric motor are connected via a relay electrical reserve with a capacity of between 0.2 and 2.2 Watt-hours per kilo of vehicle to be equipped (Wh / kg of vehicle), i.e. much lower than a power battery conventionally used in electric vehicles.

[0129] The drive train further comprises an accelerator control movable between a stop position and a maximum acceleration position and connected to an electronic control circuit comprising a controller programmed to power the electric motor from the relay electrical reserve according to a signal captured by at least one sensor fitted to the vehicle.

[0130] Using a more efficient compressed air piston engine, i.e. one that consumes less air for equivalent power than a conventional compressed air engine, therefore presents an essential advantage for developing this type of hybrid powertrain.

[0131] It is therefore also possible to control the exhaust in the same way, with the same type of valve according to the invention, but positioned at the air exhaust outlet, for example in a 4-stroke cycle.

[0132] The injection devices (and exhaust devices when used at the exhaust outlet to control the exhaust) according to the invention have been described with a two-stroke engine.

[0133] It is of course possible to adapt them to a four-stroke engine.

Claims

Mechanical compressed air injection device designed to equip a compressed air engine comprising at least one piston (1) intended to move in a chamber (5), said device comprising at least one compressed air intake valve (S), each valve being adapted to operate with a piston of the engine when the device is in the position of use in the engine, this valve comprising a first part (20) and a second part (30) mounted to slide in the direction of movement of the piston, the movement of the first part (20) being, in operation, mechanically controlled by the piston, characterized in that the first part (20) and the second part (30) are mounted to slide relative to each other in the direction of movement of the piston and in that the injection device also comprises, for each valve,a means (60) for temporarily retaining the second part (30) relative to the first part (20) so as to impose, in operation, a desynchronized movement between the second part (30) of the valve and the piston (1)., Device according to claim 1 wherein the movement of the first part (20) of the valve is controlled solely by the piston (1), while the second part (30) surrounds the first part (20) so that the first part (20) can slide inside the second part (30), the movement of the second part being controlled by the piston and by the temporary retaining means. Device according to claim 1 or 2 in which the first part (20) comprises a rod (21) integral with the piston (1), and the second part (30) is constituted by a sleeve in which the rod (21) of the first part slides, the rod (21) and the sleeve (30) being intended to be slidably mounted in a chamber (40) of the cylinder head (B) of the engine, and the length (L2) of the sleeve (30) being less than that (L1) of the rod (21). Device according to claim 3 in which the temporary retaining means consists of at least one permanent magnet (60) intended to be placed near the bottom (41) of the chamber (40). Device according to claim 4 in which the second part (30) is made at least partially of a magnetic material. Device according to one of claims 3 to 5 in which the rod (21) comprises, at its end opposite the piston, a thrust washer (22). Cylinder head intended for a compressed air engine, equipped with a device according to one of claims 1 to 6. Compressed air engine comprising a cylinder head according to claim 7. Hybrid powertrain for equipping a vehicle comprising a high-pressure compressed air reservoir connected to a compressed air piston engine according to claim 8, engaged with an electric generator for generating electricity when driven by the compressed air piston engine, the electric generator being connected to at least one electric motor connected to a transmission engaged with a moving member of the vehicle. Powertrain according to claim 9, in which the generator and said at least one electric motor are connected via a relay electrical reserve with a capacity of between 0.2 and 2.2 Watt-hours per kilo of vehicle to be equipped (Wh / kg of vehicle). Powertrain according to claim 9 or 10, further comprising an accelerator control movable between a stop position and a maximum acceleration position and connected to an electronic control circuit comprising a controller programmed to power the electric motor from the relay electrical reserve as a function of a signal captured by at least one sensor fitted to the vehicle. A generator set comprising a high pressure compressed air reservoir connected to a compressed air piston engine according to claim 8, engaged with an electric generator for generating electricity when driven by the compressed air piston engine.

Images