Mechanical 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 compressed-air injection device for a compressed-air piston engine. The device comprises a compressed-air intake valve (S), the compressed-air intake valve (S) comprising: - a bar (20) sliding in a channel perpendicular to the air intake passage admitting air into the piston chamber, the bar comprising a first part (21) provided with an intake opening (210, 211), - a return means (40) for returning the bar (20) and - at least one cam actuator (50) configured to control the movement of the bar (20) between an open position of the intake passage (110, 111), in which the intake opening (210, 211) is fully aligned with the intake passage (110, 111), and a closed position in which the intake opening (210, 211) is fully offset relative to the intake passage (110, 111).

Description

Title of the invention: Mechanical injection device for compressed air engine, compressed air engine equipped with such a device and hybrid drive chain comprising such an engine.

[0001] The present invention relates to a low air consumption compressed air engine, 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" or "gasoline" engines.

[0002] It also relates to an injection system for such an engine, a cylinder head incorporating this injection system and a hybrid drive chain including 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 industrial activities such as, for example, generator sets.

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

[0005] Indeed, there are many powertrain solutions based on internal combustion engines, electric motors, or a combination of both (called a hybrid powertrain).

[0006] Internal combustion engine 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 lies in their range and the speed at which the fuel tank can be refueled.

[0007] So-called "electric" vehicles have a drive system consisting of a battery with sufficient power to supply the electric motor(s) capable of driving a transmission connected to a means of movement (the wheels of a car or the propeller of a boat, for example).

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

[0009] The power batteries used in electric vehicles are most often lithium-ion batteries, because only this type of battery allows for power and range suitable for this use.

[0010] The major drawback of the electric drive system lies precisely in the battery.

[0011] Indeed, its manufacture and end of life are ecologically problematic: the reserves of lithium, cobalt and other constituents are theoretically insufficient to equip all the vehicles in the world, and recycling processes are currently unknown or not operational.

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

[0013] Hybrid powertrains have also been proposed in which a combustion 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] Therefore, there is a need to offer an engine and drive system that reduces the pollution generated and the risks of operation.

[0016] A classic two-stroke type compressed air piston engine is already known, and illustrated in figure 1.

[0017] The engine comprises a cylinder block A including at least one piston 1 connected to a crankshaft 2 by means of a connecting rod 3 rotatably attached to a counterweight 4. The piston 1 is mounted for translational movement (arrow F1) within a compression / expansion chamber 5, the upper end of which is closed by a cylinder head B. At its lower end, the chamber 5 includes an external air intake 6 (arrow F2), as well as an external air channel 7 (arrows F3 and F4) opening into the chamber 5 above the piston 1 when it is at bottom dead center. The chamber 5 also includes an exhaust outlet 12 to expel the compressed air released when the piston moves downward and is near its bottom dead center.

[0018] In its upper part, hermetically sealing chamber 5, the cylinder head B includes at least one compressed air inlet valve 8 (arrow F5) supplying air from a high-pressure compressed air reservoir 9 via a pressure regulator 10 (designed to reduce the air pressure from 300 bar or more coming from the reservoir to a pressure of 30 to 50 bar at the outlet to the compressed air inlet duct 11 located upstream of the inlet valve 8). The compressed air inlet valve 8 comprises a valve stem 8a, movable in translation (arrow Fl) relative to the cylinder head B, and fitted 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 specific length, so that the piston 1 pushes the valve stem upwards as it moves upwards. However, for the volume of compressed air injected to be sufficient to generate the required engine work, this opening must last for a sufficient duration. Therefore, the valve head must protrude into the chamber by a significant length, which consequently controls the valve opening well before the piston reaches top dead center.

[0020] Furthermore, in this type of engine, a volume of outside air, drawn in at atmospheric pressure when the piston is at its lowest position (bottom dead center or BDC), is compressed by the piston in the combustion chamber as it rises. The compressed air heats the chamber walls. Compressed air can then be injected from the compressed air reservoir into this heated chamber via the intake valve. The compressed air expands due to the pressure difference and the high temperature of the chamber, forcing the piston downwards and generating mechanical work. This expels the expanded air, and the cycle then repeats: outside air is drawn in, the air in the chamber is compressed by the rising piston and the chamber is heated, compressed air is injected into the chamber, generating mechanical work, and the air is expelled.

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

[0022] Indeed, a primary problem lies in the fact that, depending on the adiabatic compression ratio of the air, the cylinder temperature, when the piston is at top dead center, can exceed several hundred degrees Celsius and the pressure several tens of bars. The compressed outside air thus opposes the piston's upward movement in the final millimeters, causing the engine to lose power.

[0023] Furthermore, compressed air must always be injected at a pressure higher than that of the air compressed in the piston chamber to allow for expansion and engine work. The compression ratio of the air compressed by the piston, coming from the outside, therefore defines the minimum pressure to be injected into the cylinder, which makes it impossible to precisely control, and thus optimize, air consumption.

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

[0025] This is especially true since a compressed air engine differs from an internal combustion engine in that it injects a much larger volume of air than fuel to generate comparable engine work. It is therefore necessary to adjust the cross-section of the air passage, as well as the duration of the intake valve opening, to ensure the injection of a sufficient volume of compressed air for the intended application.

[0026] For comparison, at comparable opening times, the diameter of diesel injectors is 0.1 millimeters, whereas the opening of the passage for compressed air is about 7 millimeters, or 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] It is therefore understandable that this compressed air added to the outside air already compressed by the piston strongly opposes the end of the piston's upward movement, resulting in 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 engine reliability.

[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 determined length to allow air to pass through sequentially.

[0031] However, this groove must be long enough to allow the injection of sufficient compressed air to generate the required engine work. Consequently, air begins entering the chamber well before the piston reaches top dead center. This does not solve, and may even exacerbate, the initial problem.

[0032] This is why it was already proposed in document FR3141716 to add an ejection valve allowing the compressed air from the piston to escape just before compressed air is injected from the reservoir into the combustion chamber, in order to reduce the pressure in the chamber. It was also proposed to circulate this ejected air through a volume surrounding the chamber to further heat it, but this arrangement makes the engine design very complex without providing any significant improvement. In particular, the opening of the intake and exhaust valves is controlled by two camshafts, as in internal combustion engines, by pushing the valves into the piston chamber to open them. However, such operation necessitates a large clearance above the piston to allow the valves to open without being struck by the piston.Such a dead volume is unacceptable in a compressed air engine, as it drastically reduces the efficiency of compressed air injection by decreasing engine power.

[0033] The valve in Figure 1 could be replaced by a valve that does not protrude into the piston chamber and is actuated by a camshaft. The spring would then be a tension spring. However, as explained previously, to allow a sufficient volume of compressed air to pass through, the valve head would need to be very large. Since the compressed air enters above this valve head, a very powerful tension spring would be required to lift the valve and open the passage for the compressed air. This would impose a very strong contact force against the cams, promoting wear on the cams and consuming mechanical energy, which would drastically reduce the engine's power.

[0034] No obvious mechanical solution has yet been proposed to optimize engine power.

[0035] The objective of the present invention is therefore to propose a mechanical solution to improve engine reliability.

[0036] Another objective of the present invention is to provide a compressed air engine with lower consumption for the same generated motor power, in order to increase the autonomy and efficiency of the device equipped with said engine: vehicle or generator set.

[0037] 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 with the same quantity of air injected, or to decrease the quantity of air injected with the same driving power.

[0038] However, the inventor had the idea that an injection that would take place closer to top dead center would reduce the negative work consumed by the upward movement of the piston.

[0039] The idea behind the invention is to provide a delayed air injection system compared to the engine shown in Figure 1. This allows the piston to rise in the final millimeters of its stroke to top dead center and injects compressed air only when the piston is at or very close to top dead center (before or after), while ensuring a sufficient volume of injected air to achieve the desired power output. This will improve engine efficiency.

[0040] The present invention provides a mechanical type solution, i.e. devoid of electronics, while allowing very fine control of air injection, allowing the injection of an optimal volume of air, at an optimal position of the piston, thus maximizing air consumption.

[0041] The solution according to the invention is specifically adapted to the field of compressed air, because it allows a reduction in the electrical consumption required to open the valve, a problem which is classic in the field of air-injection engines compared to fuel injection.

[0042] Indeed, power is a major issue in the field of compressed air, much more so than in the field of internal combustion engines, which, for the same injected volumes, have greater power output. It is therefore well known that electronic compressed air injection is preferable to mechanical injection controlled by a camshaft, which consumes more engine power.

[0043] Another objective is to offer a more homogeneous mechanical injection system in the piston chamber.

[0044] Indeed, when compressed air is injected through a point valve, its distribution is not homogeneous and the expansion of the air can create areas of different stresses on the piston, increasing piston fatigue over time.

[0045] The idea behind the invention is to pivot the valve stem and valve head at right angles to the opening direction in the cylinder head, so that, with the stem perpendicular to the direction of the compressed air pressure, the movement of the stem and the opening of the compressed air passage do not oppose the flow of pressurized air, thus the mechanical work or mechanical energy required to open and close the air passage is almost zero.

[0046] An engine concerned by the invention is similar to that illustrated in figure 1, but differs from it by the particular design of the valve, the cylinder head and the valve control.

[0047] Thus, the invention relates to a mechanical compressed air injection device intended to equip a cylinder head of a compressed air engine which also includes at least one piston intended to move in a chamber, the cylinder head being internally traversed by an intake duct comprising at least one intake passage substantially parallel to the direction of compressed air injection into the piston chamber and by at least one channel perpendicular and transverse to said at least one intake passage, 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 operating position in the engine, and comprising: - a bar arranged to slide within said at least one channel, said bar comprising a first part having at least one inlet orifice, and a second part for position control, the valve further comprising, - a means of recalling the bar and, - a cam actuator configured to control the movement, during operation, of the bar in a position between an open position of said at least one intake passage in which said at least one intake orifice carried by the first part is fully aligned with said at least one intake passage, and a closed position of said at least one intake passage of the intake valve in which said at least one intake orifice carried by the first part is fully offset from said at least one intake passage. The cam actuator comprises at least one cam fixed to a camshaft.

[0048] The invention also relates to a compressed air engine cylinder head equipped with an injection device according to the invention, the cylinder head being internally traversed by at least one intake passage substantially parallel to the direction of injection of compressed air into the piston chamber and by a channel perpendicular and transverse to said at least one intake passage.

[0049] In a variant of this device, the cylinder head is also internally traversed by a compressed air discharge / charge duct comprising at least one discharge / charge passage traversed perpendicularly and transversely by a channel arranged next to the channel receiving the intake valve, the device further comprising a discharge / charge valve arranged next to the intake valve, and comprising: - a bar arranged to slide within said at least one channel, said bar comprising a first part provided with at least one discharge / charge orifice, and a second part for position control, the valve further comprising, - a means of recalling the bar and, - a cam actuator, comprising at least one cam fixed to a camshaft, configured to control the movement, in operation, of the bar in a position between an opening position of said at least one discharge / charge passage in which said at least one discharge / charge orifice carried by the first part is entirely aligned with said at least one discharge / charge passage, and a closing position of said at least one discharge / charge passage of the intake valve in which said at least one discharge / charge orifice carried by the first part is entirely offset from said at least one discharge / charge passage.

[0050] The invention also relates to a compressed air engine cylinder head equipped with an injection device according to the invention, furthermore traversed internally by at least one discharge / charge passage substantially parallel to the direction of injection of the compressed air into the piston chamber and by a channel perpendicular and transverse to said passage.

[0051] In a preferred embodiment, the injection device is intended for a compressed air engine whose cylinder head has several intake passages, distributed homogeneously with respect to the width of the piston chamber.

[0052] In this case, the cylinder head is internally traversed by a plurality of intake passages of determined opening area and substantially parallel to the direction of injection of compressed air into the piston chamber, the intake passages being spaced at a determined distance greater than or equal to the opening area of ​​the intake passages and by at least one channel perpendicular and transverse to all the intake passages, the 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 operating position in the engine and comprising a bar arranged slidably in said channel, said bar comprising a first part having as many intake ports as the cylinder head has compressed air intake passages, the intake ports being spaced at the same distance as the intake passages in the intake duct,and a second position control part, the valve further comprising a means for returning the bar and a cam actuator, comprising at least one cam fixed to a camshaft, configured to control the movement, in operation, of the bar in a position between an open intake port position in which the intake ports carried by the first part are fully aligned with the intake ports, and a closed position in which the intake ports carried by the first part are fully offset from the intake ports.

[0053] Thanks to the perpendicular arrangement of the bar or each bar relative to the direction of the compressed air intake passages, the mechanical work required to move the bar is negligible, or even zero.

[0054] The invention therefore allows a mechanically controlled compressed air injection, with very low mechanical consumption or very low auxiliary compressed air consumption (i.e. not participating in the movement of the piston, but used to activate the pneumatic actuators).

[0055] Furthermore, in the embodiment where the cylinder head includes several intake passages distributed homogeneously over the upper surface of the piston chamber, the cam control of the bar with several intake ports allows the perfectly simultaneous opening of the intake ports and therefore a homogeneous injection of compressed air into the piston chamber.

[0056] Furthermore, it is possible to control the opening of the intake passage(s) when the piston is at its top dead center, or even just after top dead center, so that the engine develops maximum power.

[0057] In a variant of this device, the cylinder head is also internally traversed by a compressed air discharge / charge duct comprising at least one discharge / charge passage traversed perpendicularly and transversely by the channel, and wherein the first part of the bar further comprises at least one discharge / charge orifice intended to align, in operation, with said at least one discharge / charge passage of the discharge / charge duct, the inlet ports and the discharge / charge orifices being arranged on the first part of the bar such that, in operation, the bar is moved directly (the cam is in contact with the end of the bar) or indirectly (the cam actuates a pneumatic actuator) by the cam actuator, in a position between: - the opening position of the intake passage, in which said at least one intake orifice carried by the first part of the bar is entirely aligned with said at least one intake orifice, while said at least one discharge / charge orifice carried by the first part of the bar is entirely offset from said at least one discharge / charge passage; - the "closed" position of said at least one inlet passage and said at least one discharge / charge passage, in which said at least one inlet orifice carried by the first part of the bar is entirely offset from said at least one inlet passage, and said at least one discharge / charge orifice carried by the first part of the bar is entirely offset from said at least one discharge / charge passage; and - a compressed air discharge / charge position in which said at least one inlet passage is closed and said at least one discharge / charge passage is open, said at least one inlet orifice carried by the first part of the bar being entirely offset from said at least one inlet passage, and said at least one discharge / charge orifice carried by the first part of the bar being entirely aligned with said at least one discharge / charge passage; the closing position being intermediate, in the movement of the bar, between the opening position and the unloading / loading position.

[0058] In another embodiment, the valve includes another bar arranged slidably in said at least one channel, this other bar comprising a first portion having as many inlet ports as the cylinder head has compressed air inlet passages, the inlet ports being spaced the same distance apart as the inlet passages, and a second position control portion, the two bars being arranged head-to-tail, the valve further comprising a means for returning the other bar and another cam actuator, comprising at least one cam fixed to a camshaft, configured to control the movement, in operation, of the other bar between an open position of the inlet passages in which the inlet ports carried by the other bar are fully aligned with the inlet passages,and a closed position in which the inlet ports carried by the other bar are completely offset from the inlet passages.

[0059] In a variant of this device, the cylinder head is also internally traversed by a compressed air discharge / charge conduit comprising at least one discharge / charge passage traversed perpendicularly and transversely by the channel, and in which the first part of each bar further comprises as many discharge / charge orifices as the discharge / charge conduit comprises discharge / charge passages, the inlet orifices and the discharge / charge orifices being arranged on the first part of each bar, such that in operation, each bar is moved between two operating positions: - A simultaneous position (PSO) of opening the inlet passage and closing the discharge / charge passage, in which each inlet orifice carried by the first part of each bar is fully aligned with said at least one corresponding inlet passage, while each discharge / charge orifice carried by the first part of each bar is fully offset from said at least one corresponding discharge / charge passage; and - A simultaneous position (PSF) of closing said at least one inlet passage and opening said at least one discharge / charge passage, in which each inlet orifice carried by the first part of each bar is fully offset from said at least one corresponding inlet passage, and each discharge / charge orifice carried by the first part (21) of each bar is fully aligned with said at least one corresponding discharge / charge passage.

[0060] In a preferred embodiment, the cam actuator is configured to directly control the movement of the bar. In this case, at least one cam attached to the camshaft is, during operation, supported against a free end of the second valve position control portion. The return means is then configured so that the free end of the second control portion follows the cam when the cam is rotated by the camshaft, and the cam is configured to move the bar, during operation, to a position between the open and closed positions of at least one intake passage and, if applicable, at least one discharge / charge passage.

[0061] Preferably, the free end of the second position control part of the bar or each bar has a follower roller intended to be in contact with the cam.

[0062] In an alternative embodiment, the cam actuator is configured to indirectly control the movement of the bar during operation. The valve comprises a pneumatic actuator connected to an auxiliary pneumatic compressed air source and equipped with an opening / closing mechanism connected to the cam actuator. In this case, the energy source for valve movement is a pneumatic compressed air source, preferably the high-pressure compressed air reserve via an auxiliary circuit that supplies compressed air to the pneumatic actuators independently of the injection of compressed air into the piston chamber.

[0063] The invention also relates to a compressed air engine cylinder head equipped with an injection device according to the invention, the cylinder head being internally traversed by a plurality of intake passages of determined opening section and substantially parallel to the direction of injection of the compressed air into the piston chamber, the intake passages being spaced at a determined distance greater than or equal to the opening section of the intake passages and by a channel perpendicular and transverse to all the intake passages.

[0064] The same configuration can be used for the exhaust on a four-stroke engine cylinder.

[0065] The invention also relates to a compressed air engine cylinder head equipped with an injection device according to the invention, further traversed internally by a plurality of discharge / charge passages of determined opening area, and substantially parallel to the direction of injection of the compressed air into the piston chamber, the discharge / charge passages being spaced at a determined distance greater than or equal to the opening area of ​​the intake passages, and by at least one channel perpendicular and transverse to all the intake passages.

[0066] The invention also relates to a compressed air engine cylinder head equipped with an injection device according to the invention, furthermore traversed internally by a plurality of discharge / charge passages with an opening cross-section identical to the opening cross-section of the intake passages, and substantially parallel to the direction of injection of the compressed air into the piston chamber, the intake passages and the discharge / charge passages being spaced at a determined distance (DI) greater than or equal to twice the opening cross-section of the intake passages.

[0067] The invention also relates to a compressed air engine incorporating a cylinder head according to the invention.

[0068] The invention also relates to a hybrid drive system intended to equip a vehicle comprising a high-pressure compressed air tank connected to a compressed air piston engine according to the invention in contact with an electric generator to generate electricity when driven by the compressed air piston engine, the electric generator being connected to at least one electric motor itself connected to a transmission in contact with a vehicle propulsion component.

[0069] Preferably, 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).

[0070] Preferably, the drive chain also includes a throttle control that can be moved between a stop position and a maximum acceleration position and is connected to an electronic control circuit including a controller programmed to supply the electric motor from the relay electrical reserve according to a signal received by at least one sensor fitted to the vehicle.

[0071] The invention relates to a generator set comprising, or intended to be associated with, a high-pressure compressed air reservoir. The generator set comprises a compressed air piston engine according to the invention, coupled to an electric generator to generate electricity when driven by the compressed air piston engine.

[0072] The invention also relates to a method for managing air in a drive system equipped with a main compressed air tank and a previous compressed air motor, comprising: - an engine block comprising N cylinders, N being an integer greater than or equal to 1, each cylinder having a chamber and a piston mounted to move in translation within said chamber between a high position called "top dead center" and a low position called "bottom dead center", the chamber comprising an exhaust outlet; and - a cylinder head associated with the engine block and capable of closing the chamber or each chamber, the cylinder head comprising, for each chamber at least one compressed air intake valve, and one discharge / charge valve; The process is characterized in that it comprises the following successive steps, for each cylinder: 1) Compression by the piston of the air present in the chamber; 2) Discharge of compressed air from the chamber to a buffer reservoir through the discharge / charge valve; 3) Intake of compressed air into the piston chamber from the main reservoir through the intake valve; 4) Charge of the air stored in the buffer reservoir to the piston chamber through the same discharge / charge valve; 5) Exhaust of the expanded air from the piston chamber to the outside through the exhaust outlet.

[0073] Thus, the invention relates to a compressed air engine comprising: - an engine block comprising at least one cylinder having a combustion chamber and a piston, said piston being mounted to move in translation within said combustion chamber, and - a cylinder head associated with the engine block and capable of closing the chamber(s), the cylinder head being internally traversed by at least one intake passage substantially parallel to the direction of compressed air injection into the piston chamber and by a channel perpendicular and transverse to said at least one passage, and comprising a mechanical compressed air injection device, 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 operating position in the engine and comprising: - a bar arranged to slide within said channel, said bar comprising a first part having at least one orifice, and a second part for position control, the valve further comprising, - a means of recalling the bar and, - a cam actuator, preferably comprising at least one cam fixed to a camshaft, configured to control the movement, in operation, of the bar in a position between an opening position of said at least one intake passage in which said at least one intake orifice carried by the first part is fully aligned with said at least one passage, and a closing position in which said at least one intake orifice carried by the first part is fully offset from said at least one passage.

[0074] In a preferred embodiment, the compressed air engine includes a cylinder head having several intake passages, distributed homogeneously with respect to the width of the piston chamber.

[0075] Thus, the invention also relates to a compressed air engine comprising: - an engine block comprising at least one cylinder having a combustion chamber and a piston, said piston being mounted to move in translation within said combustion chamber, and - a cylinder head associated with the engine block and capable of closing the chamber or chambers, the cylinder head being internally traversed by a plurality of intake passages of determined opening area and substantially parallel to the direction of injection of compressed air into the piston chamber, the intake passages being spaced at a determined distance greater than or equal to the opening area of ​​the intake passages and by a channel perpendicular and transverse to all the intake passages, the cylinder head comprising a mechanical device for injecting compressed air, 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 operating position in the engine and comprising a bar arranged to slide within said channel,said bar comprising a first part provided with as many intake ports as the cylinder head has compressed air intake passages, the intake ports being spaced the same distance apart as the intake passages, and a second position control part, the valve further comprising a bar return means and a cam actuator, preferably comprising at least one cam fixed to a camshaft, configured to control the movement, in operation, of the bar in a position between an open intake passage position in which the intake ports carried by the first part are fully aligned with the intake passages, and a closed position in which the intake ports carried by the first part are fully offset from the intake passages.

[0076] In another embodiment of the engine, the valve includes another bar arranged slidably in said channel, this other bar comprising a first part having as many intake ports as the cylinder head has compressed air intake passages, the intake ports being spaced the same distance apart as the intake passages, and a second position control part, the two bars being arranged head-to-tail, the valve further comprising a means for returning the other bar and another cam actuator, preferably comprising at least one cam fixed to a camshaft, configured to control the movement, in operation, of the other bar between an intake passage opening position in which the intake ports carried by the other bar are fully aligned with the intake passages,and a closed position in which the inlet ports carried by the other bar are completely offset from the inlet passages.

[0077] In specific and / or advantageous modes, either of these engines may include one or both of the following characteristics: - the cam actuator can be configured to directly control the movement of the bar, at least one cam fixed to the camshaft being, in operation, bearing against a free end of the second part of the valve position control, the return means being configured so that the free end of the second part of the control follows the cam when the latter is driven in rotation by the camshaft, the cam being configured to move, in operation, the bar into a position between the opening position and the closing position of said at least one intake passage and, where applicable, of said at least one discharge / charge passage; - the free end of the second position control part of the or each bar may include a follower roller intended to be in contact with the cam.

[0078] Alternatively, the cam actuator can be configured to indirectly control the movement of the bar in operation, the valve comprising a pneumatic actuator connected to a pneumatic source of compressed air equipped with an opening / closing mechanism connected to the cam actuator.

[0079] Thus, the invention also relates to a cylinder head intended to equip a compressed air engine according to the invention, equipped with an injection device according to the invention, the cylinder head being internally traversed by at least one intake passage substantially parallel to the direction of injection of the compressed air into the piston chamber and by at least one channel perpendicular and transverse to said at least one passage.

[0080] The invention also relates to a cylinder head intended to equip a compressed air engine according to the invention, equipped with an injection device according to the invention, the cylinder head being internally traversed by a plurality of intake passages of determined opening section and substantially parallel to the direction of injection of the compressed air into the piston chamber, the intake passages being spaced at a determined distance greater than or equal to the opening section of the intake passages and by at least one channel perpendicular and transverse to all the intake passages.

[0081] The invention also relates to a cylinder head intended to equip a compressed air engine according to the invention, equipped with an injection device according to the invention and further traversed internally by at least one discharge / charge passage substantially parallel to the direction of injection of the compressed air into the piston chamber and by a channel perpendicular and transverse to said passage.

[0082] The invention also relates to a cylinder head for use in a compressed air engine according to the invention, equipped with an injection device according to the invention and further traversed internally by a plurality of discharge / charge passages of determined opening area, substantially parallel to the direction of compressed air injection into the piston chamber, the discharge / charge passages being spaced at a determined distance greater than or equal to the opening area of ​​the intake passages, and by at least one channel perpendicular and transverse to all the intake passages. The cylinder head further comprises a support for a cam actuator configured to control the movement, during operation, of the rod of the mechanical compressed air injection device(s).

[0083] The invention also relates to a compressed air engine cylinder head equipped with an injection device according to the invention, equipped with an injection device according to the invention and further traversed internally by a plurality of discharge / charge passages with an opening section identical to the opening section of the intake passages, and substantially parallel to the direction of injection of the compressed air into the piston chamber, the intake passages and the discharge / charge passages being spaced at a determined distance greater than or equal to twice the opening section of the intake passages.

[0084] The invention also relates to a mechanical injection device intended to equip a compressed air engine and / or a cylinder head according to the invention, this device having the characteristics previously described.

[0085] The invention will be better understood and other objects, advantages and features thereof will become more apparent upon reading the following description, which is made with reference to the accompanying drawings, in which:

[0086] [Fig. 1] is a cross-sectional view of a conventional two-stroke type compressed air engine which has already been described previously;

[0087] [Fig. 2] represents, in figure 2a, a cross-sectional view of a first embodiment of an injection device according to the invention, the device being in the closed position, and, correspondingly in figure 2b, a top view of the bar of the device in its closed position;

[0088] [Fig. 3] represents, in figure 3a, a cross-sectional view of the first embodiment of an injection device according to the invention of figure 2a, in the open position, and, correspondingly in figure 3b, a top view of the bar of the device in its open position;

[0089] [Fig. 4] is a cross-sectional view of a second embodiment of an injection device according to the invention, the device being in the closed position;

[0090] [Fig. 5] is a cross-sectional view of the second embodiment of an injection device according to the invention, the device being in the open position;

[0091] [Fig. 6] is a cross-sectional view of the second embodiment of an injection device according to the invention, the device being in a partially open position;

[0092] [Fig. 7] represents, in figure 7a, a cross-sectional view of a variant of the first embodiment of an injection device according to the invention, the device being in the open position, and, correspondingly in figure 7b, a top view of the bar of the device in its closed position;

[0093] [Fig. 8] represents, in figure 8a, a cross-sectional view of the injection device according to the invention illustrated in figure 7, the device being in the closed position, and, correspondingly in figure 8b, a top view of the bar of the device in its closed position;

[0094] [Fig. 9] represents, in figure 9a, a cross-sectional view of a first implementation method of the air management process according to the invention, in discharge / charge phase, the discharge / charge passages being open and the intake passages being closed; correspondingly in figure 9b, a top view of the bar and correspondingly in figure 9c, a polar diagram illustrating the position of the cylinder in the PHD sector;

[0095] [Fig. 10] represents, in figure 10a, a cross-sectional view of a first implementation method of the air management process according to the invention, in the closed position of the discharge / charge passages and the inlet passages; correspondingly in figure 10b, a top view of the bar and correspondingly in figure 10c, a polar diagram illustrating the position of the cylinder between sector PHD and sector PHI;

[0096] [Fig. 11] represents, in figure 11 a, a cross-sectional view of a first implementation method of the air management process according to the invention, in the position of opening the inlet passages and closing the discharge / charge passages; correspondingly in figure 11 b, a top view of the bar and correspondingly in figure 11, a polar diagram illustrating the position of the cylinder in the sector PHI;

[0097] [Fig. 12] represents, in figure 12a, a cross-sectional view of a first implementation method of the air management process according to the invention, in the closed position of the discharge / charge passages and the inlet passages; correspondingly in figure 12b, a top view of the bar and correspondingly in figure 12c, a polar diagram illustrating the position of the cylinder between sector PHI and sector PHC;

[0098] [Fig. 13] represents, in figure 13a, a cross-sectional view of a first implementation method of the air management process according to the invention, in the charging phase, with the discharge / charging passages open and the inlet passages closed; correspondingly in figure 13b, a top view of the bar and correspondingly in figure 13c, a polar diagram illustrating the position of the cylinder in the PHC sector;

[0099] [Fig. 14] represents, in figure 14a, a cross-sectional view of a first implementation method of the air management process according to the invention, in the closed position of the discharge / charge passages and the inlet passages; correspondingly in figure 14b, a top view of the bar and correspondingly in figure 14c, a polar diagram illustrating the position of the cylinder in the PHE sector;

[0100] [Fig. 15] represents a top cross-sectional view of a second embodiment of the air management process according to the invention;

[0101] [Fig. 16] represents a cross-sectional view of a third implementation method of the air management process according to the invention, in the discharge phase, with the discharge / charge passages open and the intake passages closed;

[0102] [Fig. 17] represents a cross-sectional view of the third implementation method of the air management process according to the invention, in the closed position of the discharge / charge passages and the intake passages;

[0103] [Fig. 18] represents a cross-sectional view of the third implementation method of the air management process according to the invention, in the position of opening the inlet passages and closing the discharge / charge passages;

[0104] [Fig. 19] represents a cross-sectional view of the third implementation method of the air management process according to the invention, in the closed position of the discharge / charge passages and the intake passages;

[0105] [Fig. 20] represents a cross-sectional view of the third implementation method of the air management process according to the invention, in the charging phase, with the discharge / charging passages open and the intake passages closed;

[0106] [Fig. 21] represents a cross-sectional view of the third implementation method of the air management process according to the invention, in the closed position of the discharge / charge passages and the intake passages;

[0107] [Fig. 22] represents a schematic view of a first embodiment of a mechanical drive mechanism for the cam actuator of the injection device according to the invention, in which the camshafts rotate in a synchronized manner with the drive shaft;

[0108] [Fig. 23] represents a schematic view of a first embodiment of a mechanical drive mechanism for the cam actuator of the injection device according to the invention, in which the camshafts rotate out of sync with the drive shaft by means of an intermediate splined shaft;

[0109] [Fig. 24] represents a schematic view of a projection of the lateral surface of the grooved shaft in Figure 25;

[0110] [Fig. 25] represents a schematic view of a second embodiment of an electrical drive mechanism for the cam actuator of the injection device according to the invention; [OR I] [Fig. 26] is a Clapeyron diagram of a classic compressed air engine, illustrated in figure 1;

[0112] [Fig. 27] is a Clapeyron diagram of a compressed air motor according to the invention, of the discharge / charge type illustrated in Figures 9 to 21, in motor drive mode; and

[0113] [Fig. 28] is a Clapeyron diagram of a compressed air engine according to the invention, of the discharge / charge type illustrated in figures 9 to 21, in post-engine-brake mode.

[0114] The elements common to the different figures are designated by the same references.

[0115] In the present invention, the following terms or expressions are defined as follows: - Compressed air: air stored at high pressure in a main tank and serving as the main motive power source. - Compressed air: residual air present in the chamber after exhaust and compressed by the upward movement of the piston. - Main tank: main storage volume for high-pressure compressed air. - Buffer tank: temporary storage volume for compressed air from the chamber - Compressed air intake / exhaust: * Intake is the injection of compressed air into the piston chamber from the main reservoir through an intake valve. * Exhaust is the ejection of expanded air from the piston chamber to the outside of the engine through an exhaust outlet. - Compressed air discharge / charge:* Compressed air discharge is the evacuation, or expulsion, of compressed air from the piston chamber to a buffer reservoir through a discharge / charge valve. * Air charging is the reintroduction of air from the buffer reservoir to the piston chamber through the discharge / charging valve.

[0116] In embodiments of figures 2 to 6, and 11 to 23, the valve is actuated directly by a cam actuator 50. In embodiments of figures 7 and 8, the valve is actuated indirectly by a cam actuator 50 which is engaged with an opening / closing mechanism of a pneumatic actuator connected to the valve and to an auxiliary source of compressed air.

[0117] The first embodiment illustrated in figures 2 and 3 will now be described.

[0118] Figure 2a shows a compressed air engine with the injection system in the closed position, while piston 1 is between top dead center and bottom dead center. Figure 3a shows the same engine with the injection system in the open position, while piston 1 is at top dead center (TDC). Reference A designates the engine's cylinder block, reference B its cylinder head, and reference 5 the compression / expansion chamber in which piston 1 is mounted in translation.

[0119] The cylinder head B is drilled to provide a compressed air intake duct 11 which communicates with a high-pressure compressed air reservoir (not illustrated) and with a plurality of intake passages which open into the chamber 5 of the piston 1. Figures 2a and 3a illustrate five intake passages 110 to 114, but the invention can be implemented with at least one passage.

[0120] These intake passages 110 to 114 extend substantially parallel to the direction of injection of compressed air into chamber 5. In the example illustrated in the figures, this direction of injection corresponds to the direction of movement of the piston.

[0121] Each of these intake passages has a defined opening area SI, and two adjacent intake passages are separated by a defined distance DI, which is equal to or preferably greater than the opening area of ​​the intake passages. In the example illustrated in the figures, the area SI is the same for all intake passages, but the invention is not limited to this embodiment.

[0122] The cylinder head B is also internally traversed by a channel 13 which extends transversely to all the intake passages 110 to 114 and is therefore substantially perpendicular to the direction of movement of the piston (arrow F6).

[0123] The valve S includes a straight and elongated element or bar 20 mounted slidably in the channel 13 and comprising a first part 21 which passes through the channel 13 and a second part 22 which controls the position of the bar in the channel 13.

[0124] Figures 2 and 3 show that a sealing device 14, such as a gasket, is advantageously provided in the channel 13 around the first part 21, over at least part of its length, to ensure a seal and prevent compressed air from passing around the bar. In other words, air can only pass through the inlet port(s) provided by the bar.

[0125] Thus, the first part 21 has the general shape of a blade which is pierced with five intake ports 210 to 214. In general, the number of intake ports is equal to the number of intake passages 110 to 114 provided in the cylinder head B.

[0126] Furthermore, two adjacent intake ports are spaced by the same distance DI that separates two adjacent intake passages of the cylinder head and each intake port has an opening section SI, identical to that of the intake passages made in the cylinder head B, but the invention is not limited to this embodiment. What matters, as described later, is that the movement of the bar relative to the intake passages made in the cylinder head B allows a position of the bar between (i.e. including) an open position in which the intake ports 210, 211, 212, 213, 214 of the bar are fully aligned with the intake ports 110, 111, 112, 113, 114 of the cylinder head, and a closed position in which the intake ports 210, 211, 212, 213, 214 of the bar are fully offset from the intake ports 110, 111, 112, 113, 114 of the cylinder head.

[0127] The second part 22 comprises a component 220 connected on one side to the first part 21 and on the other side to a rod 221. The cross-section of component 220 is larger than that of the first part 21 and that of the rod 221. A return means 40 is mounted around the rod 221 and against component 220. This can be, as illustrated, a spring, in which case it is a tension spring (compression springs could also be used. It would then suffice to place a shoulder in the chamber 31 and on the valve rod 221). Alternatively, the return means could be magnets, elastomers, or a compressible gas / fluid, for example.

[0128] This second part 22 is mounted in a chamber 31 provided inside a block 30, placed on one side of the cylinder head B or integrated into the cylinder head, laterally with respect to the intake passages 110, 111, 112, 113, 114.

[0129] This chamber 31 includes a first chamber 310 whose cross-section is substantially equal to (i.e., immediately larger than) that of part 220, so as to ensure its guidance when this second part slides in the first chamber 310. On the side of the breech B, this first chamber 310 includes a bottom 312. It also includes a second chamber 311 whose cross-section is larger than that of the spring 40 and smaller than that of the first chamber 310.

[0130] Thus, a shoulder 313 is formed between the two chambers to limit the movement of the second part 22 in chamber 31.

[0131] To move the bar(s) 20, the invention provides a cam actuator 50. Such an actuator comprises one or more cams 51 of a specific shape, generally fixed to a camshaft in an eccentric manner to vary the distance between the follower (here, the free end of the rod of the second control part of the bar(s)) and the axis of rotation of the camshaft. The cam actuator 50 of the invention is fixed relative to the valves by means of a bracket attached to the cylinder head. The bracket may be located on one side of the cylinder head B or integrated into the cylinder head, for example, in a dedicated housing.

[0132] Thus, the return means 40 is configured so that the free end of the rod 221 of the second control part 22 follows the cam 51 when the latter is driven in rotation by the camshaft 52. Advantageously, the free end of the second position control section 22 of the bar or each bar 20 (see other embodiments in Figures 3 to 6 and 11 to 23) includes a follower roller intended to be in contact with the cam. This roller, mounted for free rotation on the second position control section 22, helps to limit friction and therefore the consumption of mechanical energy.

[0133] In the figures, the illustrated cams 51 have an ovoid profile and are fixed eccentrically on the camshaft 52. Thus, in operation, the end of the rod 221 of the second control part 22 is at a distance from the axis of rotation of the camshaft 52 between a maximum distance (for example see figure 2) and a minimum distance (for example see figure 3).

[0134] The use of cams in combination with the specific valve structure according to the invention is particularly advantageous and enhances engine power. Indeed, one of the benefits of using cams with the reed valve system is the reduction in the stroke required to open and close the air passages. Thus, compared to known prior art systems, the diameter and eccentricity of the cams can be reduced, thereby decreasing the weight of the actuators. In fact, more compact cams eliminate sharp angles, which reduces the risk of collisions between the cams and the valves. The service life of the entire system is extended by this reduction in the risk of collisions, and this improved contact between the cams and the valves further enhances the system's precision.

[0135] In addition, the use of a cam actuator allows the cam profiles to be adapted to different engine cycles and different engine architectures.

[0136] The operation of the injection device will now be described in more detail for an example in which the cam actuator 50 is configured to directly control the movement of the rod, at least one cam 51 fixed to the camshaft 52 being, by means of the return means 40, constantly pressed against the free end of the second part 22 of the valve position control. In other words, the cam 51 is configured to move, during operation, the rod 20 to a position between the open and closed positions of said at least one intake passage 110, 111, 112, 113, 114.

[0137] Thus, figures 2a and 2b illustrate the beginning of the engine's operating cycle, with valve S in the closed position and piston 1 moving up into chamber 5 (arrow F6). The ambient air in chamber 5 is then compressed and its temperature rises.

[0138] In this closed position, the cam 51 is in a position such that the part 220 is pushed against the wall 312 by the return spring 40.

[0139] As Figure 2b illustrates more precisely, in this position, the intake ports 210 to 214 in the first part 21 of the bar 20 are not aligned with the intake ports 110 to 114 in the cylinder head; that is, they are completely offset from the intake ports 110 to 114 in the cylinder head. Consequently, the bar 20 (and the sealing gasket 14) prevents any compressed air from entering chamber 5.

[0140] Figure 3a illustrates piston 1 at its top dead center (TDC). Since the cam mechanism 50 is synchronized with the engine cycle, in this piston position, cam 51, combined with the return mechanism 40, causes the bar 20 to move. This translational movement causes the second part 22 of the bar to move away from the cylinder head B, until part 220 comes to rest against the shoulder 313.

[0141] As Figure 3b illustrates more precisely, in this open position, the inlet ports 210 to 214 in the first part 21 of the bar 20 are entirely aligned with the inlet passages 110 to 114 (see Figure 3b). Therefore, the bar 20 allows compressed air to enter chamber 5.

[0142] The air contained in chamber 5 then expands, which pushes piston 1 downwards (opposite direction of arrow F6).

[0143] The cam mechanism 50 being synchronized with the engine cycle, once the required volume of injected compressed air is reached, the cam 51 is in a position such that the bar 20 moves in translation, causing the second part 22 of the bar to approach the cylinder head B, until the part 220 comes to rest on the bottom 312 of the first chamber 310.

[0144] Valve S is then back in the closed position illustrated in figure 2a and all air intake is prevented.

[0145] The opening and closing of the valve is controlled mechanically by tracking cam 51. The timing, shape of the cam, and rotational speed of the shaft are configured to optimize air injection and valve closure. This makes it possible to inject compressed air in the immediate vicinity of the piston's top dead center, with very low mechanical energy consumption and high precision.

[0146] The downward translational movement of the piston continues until it reaches its bottom dead center.

[0147] Piston 1 can then move upwards for a new cycle.

[0148] The preceding description shows that the first part 21 of the bar acts as a shutter by cooperating with the intake passages 110 to 114 to close or open them and is therefore, from a functional point of view, similar to a valve head.

[0149] Furthermore, the second part 22 of the bar ensures its guidance and is, from a functional point of view, similar to a valve stem.

[0150] The injection device just described includes a plurality of intake passages for compressed air in the cylinder head B and a plurality of intake orifices in the bar 20. The invention is not limited to this embodiment however and the cylinder head B could include only a single intake passage 10 for compressed air opening into the piston chamber and a single intake orifice 10 in the first part of the bar.

[0151] This embodiment makes it possible to take advantage of the structure of the stem and the valve head and their arrangement perpendicular to the direction of movement of the piston and to the direction of injection of compressed air into the piston chamber (therefore the direction of the intake passages in the cylinder head), in order to distribute the volume of compressed air injected into the piston chamber by adjusting the position of the bar 20 relative to the channel 13.

[0152] A second embodiment is illustrated in figures 4 to 6.

[0153] The valve S' comprises a bar 20, associated with a return spring 40, a block 30 in which the second part 22 of the bar slides, and another cam actuator 50, as described in detail with reference to Figures 2a to 3b. It also comprises these same parts arranged opposite each other on the other side of the cylinder head. The latter has the same structure as the cylinder head illustrated in Figures 2a and 3a.

[0154] In other words, the valve S' comprises another bar 20a identical to the bar 20, associated with a return spring 40a, a block 30a in which the second part 22a of the bar slides, and another cam actuator 50a. The intake ports 210a, 21a, 212a, 213a, 214a made in this bar 20a therefore have an opening area SI and are spaced by the same distance DI that separates two adjacent intake passages of the cylinder head.

[0155] The two bars 20 and 20a are arranged end-to-end, such that their first sections 21 and 21a, pierced with intake ports, are parallel and slide inside the channel 13 formed in the cylinder head. The size of this channel is modified accordingly. Alternatively, it is possible to provide another channel parallel to channel 13 and receiving the bar 20a.

[0156] As before, the camshafts 50 and 50a are synchronized to the engine cycle so as to independently move each bar into a position between (i.e., including) a closed position and an open position.

[0157] Thus, by combining two bars 20 and 20a oriented head-to-tail and parallel, and by controlling them independently, i.e. differentially, it is possible to move one a little more than the other and, consequently, to modulate the section of the openings resulting from the superposition of the inlet ports of each bar.

[0158] In other words, as illustrated in Figure 4, when the camshafts 52 and 52a are at a minimum distance from the valve bars, the parts 220 and 220a are pushed against the bottoms 312 and 312a of the first chambers 310, 310a by the return spring 40, 40a.

[0159] In this position, the two bars 20 and 20a are arranged so that their intake ports, formed in the first part 21 and 21a of each bar, coincide but are not aligned with the intake passages 110 to 114 in the cylinder head. Consequently, bars 20 and 20a prevent any compressed air from entering chamber 5, and valve S' is in the closed position. It is clear that if only one of the bars is in the closed position, all air passage is blocked.

[0160] Figure 5 shows that by simultaneously and identically controlling the movement of the two bars 20 and 20a by the cam actuators 50 (the camshafts 52 and 52a are at their maximum distance from the valve bars), the inlet ports of each bar align completely and perfectly, providing a maximum opening area for the compressed air. Valve S' is therefore in the fully open position.

[0161] Alternatively, as illustrated in Figure 6, by simultaneously but differently controlling the movement of the two bars 20 and 20a (for example, by offsetting the position or rotation of the cams), the intake ports of each bar are offset (the axes of the intake ports of the first bar, shown as dashed lines, are offset from the axes of the intake ports of the second bar, shown as dashed lines). Thus, the cross-sectional area of ​​the opening resulting from the offset overlap of the intake ports of the two bars is smaller than the cross-sectional area of ​​the intake ports. The volume of compressed air injected into the piston chamber can therefore be modulated, for example, according to the engine temperature, its operating speed, the required acceleration, the road gradient requiring a temporary power boost, etc.The rotational speed of the camshafts must then be able to be controlled, for example based on information obtained from sensors (see figure 25).

[0162] As a corollary, the differential control of the two bars allows an opening / closing reaction of the intake passages twice as fast as with a single bar, since the two bars are actuated in the same direction, but in opposite directions, so that each intake passage is closed when each bar is moved a distance equal to half the diameter of each orifice, whereas in a device with a single bar, each intake passage is closed when the bar is moved a distance equal to the diameter of each orifice.

[0163] Air injection is therefore much more precise, so that engine consumption is reduced while offering maximum power thanks to a homogeneous injection of compressed air, and at the moment when the piston is in an optimized position, i.e. at its top dead center, slightly before or slightly after.

[0164] Furthermore, since the mechanical work required to move the bar(s) is negligible or even zero, the mechanical power consumption of the injection device according to the invention is very low. Almost all of the generated motive power can therefore be devoted to vehicle propulsion or drive, without needing to divert a large portion to actuate the cam actuators 50.

[0165] It is also possible to indirectly control the movement of the bars by replacing, in the examples given, the camshafts in contact with the free end of the bars with pneumatic actuators. In this case, they are preferably supplied with compressed air from the compressed air reservoir via an auxiliary network comprising a pressure regulator and valves controllable by the cam actuators 50. The second part 22 of the position control is then connected to the pneumatic actuator which will control the movement of the bar 20-20a.

[0166] This variant is illustrated in figures 7 and 8, which will now be described.

[0167] Figure 7a represents a compressed air engine with the injection device in the open position and therefore corresponds to Figure 3a, to whose description one can refer.

[0168] Similarly, figure 8a represents this same engine with the injection device in the closed position and therefore corresponds to figure 2a, to the description of which one can also refer.

[0169] In this variant, a distributor V is provided which includes a compressed air access in fluidic communication with the chamber 31 provided in the block 30, by means of a conduit Cl, a compressed air inlet in fluidic communication with a compressed air reservoir R by means of a conduit C2, and a compressed air outlet C3.

[0170] The distributor V also includes a sliding spool T which is actuated by the cam actuator 50c.

[0171] The spring 40 is calibrated to the pressure of the compressed air present in the reservoir R so as to ensure that the blade, or first part 21, is held in either the open or closed position. Figures 7 and 8 illustrate the situation in which the spring 40 is calibrated to ensure that the blade is held in the open position.

[0172] Thus, to move the blade 21 from the open position illustrated in figure 7 to the closed position illustrated in figure 8, the sliding drawer T is actuated by the cam of the cam actuator 50c to open the air inlet and pass the air from the reservoir R into the first chamber 310 through the conduit Cl and thus push the part 220 of the second part 22 towards the bottom 314 of the second chamber 311.

[0173] Similarly, to move the blade 21 from the closed position illustrated in Figure 8 to the open position illustrated in Figure 7, the sliding drawer T is actuated to close the air inlet and open the air outlet of the distributor V and ensure the exhaust of the air present in the first chamber 310 for example to an air recovery circuit C3.

[0174] Of course, the operation will be reversed if spring 40 is calibrated to ensure that the blade remains in the closed position.

[0175] Furthermore, similar pneumatic actuators can also be provided for the valve illustrated in figures 4 to 6, which has two bars.

[0176] The use of pneumatic actuators is also very energy-efficient thanks to the availability of medium-pressure air.

[0177] A particularly interesting application of the engine according to the invention is to integrate it into a hybrid drive system intended to equip a vehicle comprising a high-pressure compressed air tank connected to a compressed air piston engine according to the invention coupled with an electric generator to generate electricity when driven by the air piston engine.

[0178] Such a drive chain is described in document FR3150149.

[0179] The vehicle also includes at least one electric motor connected to a transmission engaged with a vehicle propulsion component.

[0180] The generator and said at least one electric motor are advantageously 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), that is to say much lower than a power battery conventionally used in electric vehicles.

[0181] The drive chain also includes a throttle control that can be moved between a stop position and a maximum acceleration position and is connected to an electronic control circuit comprising a controller programmed to supply the electric motor from the relay electrical reserve according to a signal picked up by at least one sensor fitted to the vehicle.

[0182] Using a more efficient compressed air piston engine, i.e. one that consumes less air at equivalent power than a conventional compressed air engine, therefore presents an essential advantage for developing this type of hybrid powertrain.

[0183] 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.

[0184] 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.

[0185] It is of course possible to adapt them to a four-stroke engine, in particular by equipping the exhaust with valves identical to those described for injection, but whose operation is adapted to open the passage(s) in order to eject the air used during the previous phase.

[0186] The management of air during the cycle can be advantageously improved thanks to the invention. In particular, by cleverly managing the air compressed by the piston during its upward stroke, a less energy-intensive piston return stroke is possible, and the intake of compressed air can be delayed as closely as possible to the top dead center of the piston.

[0187] Thus, the invention also relates to a method for managing air in a drive system equipped with a main compressed air tank and a compressed air motor comprising: - an engine block comprising N cylinders, N being an integer greater than or equal to 1, each cylinder having a chamber and a piston mounted to move in translation within said chamber between a high position called "top dead center" and a low position called "bottom dead center", the chamber including an exhaust outlet; and - a cylinder head associated with the engine block and capable of closing the chamber or each chamber, the cylinder head comprising, for each chamber, at least one compressed air intake valve, and one discharge / charge valve; The process is characterized in that it comprises the following successive steps, for each cylinder: 1) Compression by the piston of the air present in the chamber; 2) Discharge of compressed air from the chamber to a buffer reservoir through the discharge / charge valve; 3) Intake of compressed air into the piston chamber from the main reservoir through the intake valve; 4) Air stored in the buffer reservoir is charged to the piston chamber through the relief / charge valve, i.e., through the same passage used by the air during the relief stage; 5) The expanded air is exhausted from the piston chamber to the outside through the exhaust outlet.

[0188] The invention also relates to an air management circuit for a compressed air engine connected to a main compressed air tank, the engine comprising: - an engine block comprising N cylinders, N being an integer greater than or equal to 1, each cylinder having a chamber and a piston mounted to move in translation within said chamber between a high position called "top dead center" and a low position called "bottom dead center", the chamber including an exhaust outlet; and - a cylinder head associated with the engine block and capable of closing the chamber or each chamber, the cylinder head comprising, for each chamber, at least one compressed air intake valve; The air management circuit is characterized in that it comprises: * a relief / charge valve in the chamber of each cylinder * a buffer reservoir in fluidic communication with each relief / charge valve * a means of controlling each valve of discharge / charge.

[0189] The buffer tank comprises either a common volume connected to the discharge / charge valve of each chamber, or a multitude of individual volumes each connected to a discharge / charge valve.

[0190] The invention also relates to a compressed air engine comprising: - an engine block comprising N cylinders, N being an integer greater than or equal to 1, each cylinder having a chamber and a piston mounted to move in translation within said chamber between a high position called "top dead center" and a low position called "bottom dead center", the chamber including an exhaust outlet; and - a cylinder head associated with the engine block and capable of closing the chamber(s), the cylinder head comprising, * in the chamber of each cylinder: a compressed air inlet valve, a relief / charge valve for compressed air by the upward movement of the piston, in use; * and a buffer reservoir in fluidic communication with each discharge / charge valve.

[0191] A first embodiment of the implementation of the process according to the invention is described in figures 9 to 14 for an engine equipped with the injection device described and illustrated previously.

[0192] Each figure 9 to 14 comprises three sub-figures: a first numbered "a" which illustrates a schematic cylinder seen in section, a second numbered "b" which illustrates the bar seen from above, and a third numbered "c" which is a polar diagram illustrating the position of the cylinder in the motor cycle of the process according to the invention.

[0193] In a polar diagram, the engine cycle is indicated as a function of the position in degrees of the crankshaft which has a rotational movement from 0° to 360° (i.e. a return to 0°).

[0194] The engine's Top Dead Center (TDC) is the highest position of the piston in the engine cylinder. In the examples shown, it is fixed at the 90° position of the crankshaft.

[0195] The Bottom Dead Center (BDC) of the engine is the lowest position of the piston in the engine cylinder. It is therefore fixed, in the illustrated examples, at the 270° position of the crankshaft (i.e., 180° after / before TDC).

[0196] In the illustrated examples, the angles are given as an indication and not as a limitation, and allow for a simplified understanding of the engine cycle obtained by the air management process according to the invention.

[0197] On each illustrated polar diagram: - the compressed air injection phase by the intake valve is represented by a continuous inline PHI sector between 85° and 120°, thanks to the delayed injection described previously; - the exhaust phase of the air expanded by the exhaust outlet 12 is represented by a sector PHE in dashed dots between 210° and 330°.

[0198] According to the air management method of the invention described in more detail below with respect to several embodiments, the engine cycle comprises two additional phases, illustrated on each polar diagram: - a "discharge" phase of the compressed air released by the piston's upward movement into a buffer reservoir outside the chamber, represented by a dotted PHD sector, between 15° and 50°; and - a "charging" phase of compressed air from the buffer tank to the chamber, represented by a PHC sector in dashes, between 130° and 165°.

[0199] These two steps are done with compressed air, through the same passage(s), without using the compressed air injection passage(s).

[0200] Again, these values ​​are given as a guide. In particular, the start of the discharge phase can be chosen according to the desired pressure for the compressed air, this air then being temporarily recovered in a buffer reservoir and then reintroduced to add pressure during the piston's descent.

[0201] Similarly, the discharge phase can stop immediately before the start of the injection phase (in the example it would stop at 85°) in order to facilitate the piston's upward movement as much as possible, or, as illustrated, the discharge phase can stop a few degrees before the injection phase (it would then stop a few degrees to a few tens of degrees before 85°, here 35° before since it stops at 50°) to create a slight compression which, if it slightly opposes the piston's upward movement, generates a temperature rise in the chamber, favorable to the expansion of the compressed air injected subsequently.

[0202] In detail, in the first embodiment shown in Figures 9 to 14, the cylinder head B includes, as in the embodiment shown in Figures 2 and 3, a compressed air intake duct 11 connected to the main high-pressure compressed air storage tank 9 (not shown in the figures for clarity). The air intake duct 11 includes at least one intake passage (two are shown here) 110, 111, substantially parallel to the direction of compressed air injection into the chamber 5 of the piston 1.

[0203] The cylinder head B is also internally traversed by a channel 13 perpendicular and transverse to the intake passages 110, 111 of the intake duct 11.

[0204] As before, channel 13 is equipped with a compressed air intake valve comprising a bar 20 arranged slidably in channel 13, the bar 20 comprising a first part 21 provided with as many intake ports as the cylinder head comprises intake passages 110, 111 (here two), and a second part 22 for position control.

[0205] The intake valve further includes a return means 40 and a cam actuator 50, comprising at least one cam 51 fixed to a camshaft 52, configured to control the movement, in operation, of the bar.

[0206] According to this aspect of the invention, the intake valve performs an additional function in managing the air compressed by the upward movement of the piston. It is therefore an intake and air discharge / charge valve.

[0207] To this end, the cylinder head B also includes a compressed air discharge / charge conduit 400 comprising at least one discharge / charge passage (here two are illustrated) 401, 402, substantially parallel to the direction of injection of the compressed air into the chamber 5 of the piston 1. The channel 13 is therefore perpendicular and transverse to said at least one discharge / charge passage.

[0208] To this end also, the first part 21 of the bar includes two types of orifices (see figure 9b): at least one inlet orifice (here two) intended to align, in operation, with said at least one inlet passage 110, 111 of the air from the compressed air inlet duct 11, and at least one discharge / charge orifice (here two) 410, 411 intended to align, in operation, with said at least one discharge / charge passage 401, 402 of the compressed air discharge / charge duct 400.

[0209] The inlet ports 110, 111 and the discharge / charge ports 410, 411 are arranged on the first part 21 of the bar 20, such that the movement of the bar allows three positions for using the bar: - An "open" position of the inlet passage 110, 111 in which said at least one inlet orifice 210, 211 carried by the first part 21 of the bar 20 is fully aligned with said at least one corresponding inlet passage 110, 111, whereas said at least one discharge / charge orifice 410, 411 carried by the first part 21 of the bar 20 is fully offset from said at least one corresponding discharge / charge passage 401, 402; - A "closed" position of said at least one inlet passage 110, 111 and said at least one discharge / charge passage 401, 402, in which said at least one inlet orifice 210, 211 carried by the first part 21 of the bar 20 is entirely offset from said corresponding at least one inlet passage 110, 111, and said at least one discharge / charge orifice 410, 411 carried by the first part 21 of the bar 20 is entirely offset from said corresponding at least one discharge / charge passage 401, 402; - A compressed air discharge / charge position in which said at least one inlet passage 110, 111 is closed and said at least one discharge / charge passage 401, 402 is open, said at least one inlet orifice 210, 211 carried by the first part 21 of the bar 20 being entirely offset from said at least one corresponding inlet passage 110, 111, and said at least one discharge / charge orifice 410, 411, carried by the first part 21 of the bar 20, is entirely aligned with said at least one corresponding discharge / charge passage 401, 402.

[0210] During the injection phase (PHI), the bar is in the open position; during the discharge phase (PHD), the bar is in the discharge / charge position; and during the charging phase (PHC), the bar is in the discharge / charge position.

[0211] Between these phases, as well as in the PHE escape phase, the bar is in the position of closing all passages.

[0212] The movement of the bar takes place between the open position and the unloading / loading position, the closing position being intermediate, in the movement of the bar, between the two aforementioned positions.

[0213] To this end, each of the inlet passages and discharge / charge passages has an identical determined opening section SI, and two adjacent inlet passages and two adjacent discharge / charge passages are separated by a determined distance DI which is equal to at least twice the opening section of the inlet passages.

[0214] Furthermore, two adjacent intake ports and two adjacent discharge / charge ports are spaced by the same distance DI that separates two adjacent intake and discharge / charge passages in the cylinder head, and each intake port and each discharge / charge port has an opening area SI, identical to that of the intake and discharge / charge passages made in cylinder head B. What matters, as described later, is that the displacement of the bar relative to the intake and discharge / charge passages made in cylinder head B allows a position of the bar between (i.e., including) the open position and the discharge / charge position, the closed position being intermediate, in the displacement of the bar, between the two aforementioned positions.

[0215] The configuration illustrated in Figure 9 is the discharge / charge position. In this configuration, the discharge / charge ports 410, 411 carried by the first part 21 of the bar 20 are fully aligned with the discharge / charge passages 401, 402. Furthermore, the inlet ports 210, 211 carried by the first part 21 of the bar 20 are fully offset from the inlet passages 110, 111.

[0216] This configuration allows for the implementation of a discharge phase (figure 9) or a charging phase (figure 12).

[0217] Position P9, illustrated in Figure 9, corresponds to the discharge phase. As shown in Figure 9c, position P9 is located in sector PHD, at a 30° crankshaft orientation.

[0218] When piston 1 rises (arrow F6), the air present in the chamber, above the piston, is evacuated (arrow F7) through discharge / charge passages 401, 402 into discharge / charge conduit 400 towards buffer reservoir 500.

[0219] In the illustrated embodiment, this phase is carried out after compression since the discharge phase PHD (i.e., opening of discharge / charge passages) starts at 15° while the exhaust phase PHE ends at 330°.

[0220] In Figure 10, the piston continues to rise (arrow F6). The bar has been moved by cam 51 so that the intake and exhaust / charge ports are completely offset from the passages; that is, they all face the cylinder head wall and are thus all closed. The air in the chamber above the piston can no longer be discharged into the buffer reservoir 500. It is therefore compressed and heats up.

[0221] As illustrated in Figure 10c, the PI O position is located between the PHD sector and the PHI injection sector, at 60° crankshaft orientation.

[0222] Position Pl 1, illustrated in Figure 11, is the opening position of the inlet passages 110, 111 in which the inlet ports 210, 211 carried by the first part 21 of the bar 20 are fully aligned with the inlet passages 110, 111. Furthermore, the discharge / charge ports 410, 411 carried by the first part 21 of the bar 20 are fully offset from the discharge / charge passages 401, 402.

[0223] As illustrated in Figure 11c, position Pl 1 is located in sector PHI, at 105° crankshaft orientation. In this position, the piston has passed its top dead center, and the injection of compressed air into the chamber (arrow F8) and its expansion push the piston downwards (arrow F9), as it cannot escape through the closed discharge / charge passages 401, 402.

[0224] The expansion of the compressed air is all the greater when the chamber has been heated by the compressed air between the end of the discharge phase PHD (here at 50°) and the beginning of the injection phase PHI (here at 85°).

[0225] Once sufficient compressed air has been admitted into the chamber, the injection phase ends. The pressure in the chamber is very high, but will decrease as the air expands and piston 1 moves down.

[0226] This situation is illustrated in figure 12c in which position PI 2 is located between the intake sector PHI and the charge sector PHC, at 125° crankshaft orientation.

[0227] In this position, the bar 20 is in the position of closing the inlet passages 110, 111 and the discharge / charge passages 401, 402. The inlet ports 210, 211 are completely offset from the inlet passages 110, 111, and the discharge / charge ports 410, 411 are completely offset from the discharge / charge passages 401, 402.

[0228] Once the pressure in the chamber is less than the pressure of the compressed air stored in the buffer tank, the rotation of the cam 51 causes the bar 20 to be moved back into the discharge / charge position: the inlet passages 110, 111 are closed and the discharge / charge passages 401, 402 are open.

[0229] As illustrated in Figure 13c, position PI 3 is located in the PHC sector, at 150° crankshaft orientation, and corresponds to the charging phase.

[0230] In this position illustrated in figure 13, the compressed air is loaded (arrow F10) into the chamber, which increases the pressure and therefore the force applied to push the piston downwards, thus adding extra power.

[0231] Once the compressed air is fully charged into the chamber, bar 20 is again driven to move to the position where all passages are fully closed, as illustrated in Figure 14. The piston continues its downward movement. In Figure 14, position PI 4 is located in sector PHE, at 325° crankshaft rotation. The piston has therefore passed bottom dead center.

[0232] Exhaust outlet 12 was opened by the downward movement of the piston, and the air present in the chamber escapes to the outside of the engine.

[0233] Driven by the crankshaft powered by the other cylinders of the engine, piston 1 rises and the cycle begins again.

[0234] This first embodiment has the advantage of controlling only one bar. However, this control must be done between three positions: two extreme positions (open position and unloading / loading position) and one intermediate position (closed position).

[0235] It therefore requires very precise adjustment.

[0236] The second implementation of the process in Figure 15 is simpler in design. In this figure, the cylinder head B is seen from above and one of the chambers 5 that it covers is visible through it.

[0237] In this second embodiment, the cylinder head is provided, above the chamber of each cylinder, with two identical valves 601-602 arranged side by side, each valve being similar to that which has been described in figures 2 and 3, one being controlled for the admission of compressed air into the chamber, the other being controlled for the discharge and the charging of compressed air by the piston.

[0238] More specifically, the cylinder head includes: - an intake duct comprising at least one intake passage 110, 111, 112, 113, 114, substantially parallel to the direction of compressed air injection into chamber 5, and a channel 13a perpendicular and transverse to said at least one intake passage - a first compressed air intake valve 601; - a discharge / charge conduit comprising at least one discharge / charge passage 401, 402, 403, 404, 405 substantially parallel to the direction of compressed air injection into chamber 5, and a channel 13b perpendicular and transverse to said at least one discharge / charge passage, and - a second valve 602 for relieving / charging compressed air during the upward movement of the piston.

[0239] Each valve includes, as previously described, a bar 20b, respectively 20c, arranged slidably in its corresponding channel 13a, respectively 13b. Each bar 20b, respectively 20c includes a first part 21 provided with at least one orifice: the bar 20b includes inlet orifices 210, 211, 212, 213, 214 and the bar 20c includes discharge / charge orifices 410, 411, 412, 413, 414;

[0240] As described previously, each bar also includes a second position control part 22, a bar return means 40 20 and at least one cam actuator 50.

[0241] For the implementation of the air management method according to the invention, the inlet valve Sa is controlled in the open position during the inlet phase PHI, and in the closed position for the remainder of the cycle (i.e., during the discharge phase PHD, the charge phase PHC, the exhaust phase PHE, and between phases). Simultaneously, the discharge / charge valve is controlled in the open position during the discharge phase PHD, during the charge phase PHC, and in the closed position for the remainder of the cycle (i.e., during the inlet phase PHI, the exhaust phase PHE, and between phases).

[0242] A third embodiment of the device for managing the air compressed by the piston is illustrated in Figures 16 to 21. This embodiment allows for very fast and efficient management, combining the advantages of the first and second embodiments of Figures 9 to 15.

[0243] This third embodiment is similar to the embodiment illustrated in figures 4 to 6, the cylinder head having two valves 701-702 whose bars 20d-20e are arranged one above the other, and in opposition, i.e. head-to-tail, on either side of the axis of symmetry of the cylinder.

[0244] As with the embodiment shown in Figures 9 to 14, the cylinder head B comprises, for each cylinder, a compressed air intake duct 11 connected to the main high-pressure compressed air storage tank 9 (not shown in the figures for clarity), and a compressed air discharge / charge duct 400. These ducts 11 and 400 are identical in structure and function to those described for Figures 9 to 14.

[0245] Unlike these figures, the cylinder head B is also internally traversed by two channels 13 arranged one above the other (or alternatively a double-height channel to receive two superimposed bars), and perpendicular and transverse to the intake passages 110, 111 of the intake conduit 11 and to the discharge / charge passages 401-402 of the discharge / charge conduit 400.

[0246] Valves 701-702 each perform the two functions of compressed air intake and compressed air discharge / charge.

[0247] To this end, the bar 20d-20e of each valve has as many intake ports as the intake duct 11 has intake passages, and as many discharge / charge ports as the discharge / charge duct has discharge / charge passages.

[0248] The inlet ports 110, 111 and the discharge / charge ports 410a, 411a, 410b, 411b are arranged on the first part 21 of each bar 20d-20e, such that each bar 20d-20e can move between (i.e. including) only two operating positions: - A simultaneous PSO position of opening the inlet passages 110, 111 and closing the discharge / charge passage, in which each inlet orifice 210a, 21la, 210b, 211b carried by the first part 21 of each bar 20d-20e is fully aligned with a corresponding inlet passage 110, 111, while each discharge / charge orifice 410a, 411a, 410b, 411b carried by the first part 21 of each bar 20d-20e is fully offset from the corresponding discharge / charge passage 401, 402; - A simultaneous PSF position of closing the inlet passages 110, 111 and opening the discharge / charge passages 401, 402, in which each inlet orifice 210a, 21la, 210b, 211b carried by the first part 21 of each bar 20d-20e is entirely offset from the corresponding inlet passage 110, 111, and each discharge / charge orifice 410a, 41la, 410b, 411b carried by the first part 21 of each bar 20d-20e is entirely aligned with the corresponding discharge / charge passage 401, 402.

[0249] With the 20d and 20e bars of the 701-702 valves in opposition, the inlet ports and the discharge / charge ports are arranged with respect to each other and to the inlet and discharge / charge passages in such a way that it is possible to control the two bars in order to obtain, in operation, the three operating situations: the opening of the inlet passages to inject compressed air into the chamber, while the discharge / charge passages are closed, the opening of the discharge / charge passages to discharge compressed air out of the chamber or to charge compressed air stored in the buffer reservoir to the chamber, while the inlet passages are closed, and finally, the closing of all the inlet and discharge / charge passages.

[0250] Figures 16 to 21 correspond respectively to the phases of the motor cycle illustrated by figures 9 to 14. The corresponding polar diagrams would be identical to those illustrated in figures 9c to 14c.

[0251] Figure 16 illustrates the PHD discharge phase of the compressed air by the piston out of the chamber and towards the buffer reservoir 500 (this figure therefore corresponds to the phase illustrated in figure 9 and to position P9 on the polar diagram of figure 9c).

[0252] To this end, bar 20d and bar 20e are both simultaneously in the PSF position, closing the inlet passages 110 and 111 and opening the discharge / charge passages 401 and 402. The discharge / charge passages are then open and the inlet passages are closed. The compressed air can thus be discharged from the chamber (arrow F7) into the buffer tank.

[0253] Figure 17 illustrates the next phase in which the chamber is closed after the discharge of the compressed air (this figure therefore corresponds to the phase illustrated in figure 10 and to position P10 on the polar diagram of figure 10c).

[0254] To this end, the bar 20e remains in the simultaneous PSF position of closing the inlet passages 110, 111 and opening the discharge / charge passages 401, 402, while the bar 20d is moved (arrow Fl 2) by the cam actuator 50 into the simultaneous PSO position of opening the inlet passages 110, 111 and closing the discharge / charge passages 401, 402. The inlet and discharge / charge passages are then closed.

[0255] The air above the piston can no longer escape from the chamber. It is then compressed by the piston and heats up. Therefore, this step only requires the operation of a single bar.

[0256] The shape of one of the cams 51 can be adapted so that only one of the bars moves at that time. Alternatively, the rotation of the cams can be slightly out of phase. In another version, if the camshaft rotations are controlled independently (for example, if they are driven by independent electric motors connected to a control unit), only one of the camshafts is controlled so that only one of the bars moves at that time.

[0257] Figure 18 illustrates the next phase, which is the admission phase PHI in which compressed air is injected (arrow Fl 3) into the chamber (this figure therefore corresponds to the phase illustrated in figure 11 and to the position Pl 1 on the polar diagram of figure 11).

[0258] To this end, the bar 20d remains in the simultaneous PSO position of opening the inlet passages 110, 111 and closing the discharge / charge passages 401, 402, while the bar 20e is piloted to move (arrow Fl 4) into the simultaneous PSO position of opening the inlet passages 110, 111 and closing the discharge / charge passages 401, 402. The discharge / charge passages are then closed and the inlet passages are opened so that compressed air can be injected into the chamber.

[0259] Once again, moving to this stage therefore only requires ordering a single bar.

[0260] Figure 19 illustrates the next phase in which the chamber is closed after the admission of compressed air into the chamber (this figure therefore corresponds to the phase illustrated in figure 12 and to position PI 2 on the polar diagram of figure 12c).

[0261] To this end, the 20e bar remains in the simultaneous PSO position of opening the inlet passages 110, 111 and closing the discharge / charge passages 401, 402, while the 20d bar is piloted to move (arrow Fl 5) into the simultaneous PSF position of closing the inlet passages 110, 111 and opening the discharge / charge passages 401, 402. The inlet and discharge / charge passages are then closed.

[0262] Again, moving to this stage therefore only requires ordering a single bar.

[0263] Figure 20 illustrates the next phase, which is the PHC charging phase of the compressed air stored from the buffer tank to the chamber (arrow Fl 6). This figure therefore corresponds to the phase illustrated in Figure 13 and to position PI 3 on the polar diagram in Figure 13c.

[0264] To this end, the bar 20d remains in the simultaneous PSF position of closing the inlet passages 110, 111 and opening the discharge / charge passages 401, 402, while the bar 20e is piloted to move (arrow Fl 7) into the simultaneous PSF position of closing the inlet passages 110, 111 and opening the discharge / charge passages 401, 402. The discharge / charge passages are then open and the inlet passages are closed.

[0265] As before, moving to this stage therefore only requires ordering a single bar.

[0266] Finally, Figure 21 illustrates the next phase, which is the PHE escape phase, in which the chamber is closed after the chamber is charged with compressed air from the buffer reservoir (this figure therefore corresponds to the phase illustrated in Figure 14 and to position P14 on the polar diagram in Figure 14c).

[0267] To this end, one of the two bars 20d or 20e is moved. This is not very important since, to restart the cycle, this bar will need to be moved again to return to the position shown in Figure 16. In Figure 21, it is bar 20d that remains in the simultaneous PSF position, closing the inlet passages 110, 111 and opening the discharge / charge passages 401, 402, while bar 20e is driven to move (arrow Fl 8) to the simultaneous PSO position, opening the inlet passages 110, 111 and closing the discharge / charge passages 401, 402. The inlet and discharge / charge passages are then closed.

[0268] Again, moving to this stage therefore only requires ordering a single bar.

[0269] For the implementation of this embodiment, each of the inlet passages and discharge / charge passages has a determined opening section SI and, as in the embodiment of Figures 4 to 6, two adjacent inlet passages and two adjacent discharge / charge passages are separated by a determined distance DI which is equal to at least once the opening section of the inlet passages (whereas it is at least twice for the embodiment of Figures 9 to 14).

[0270] Furthermore, two adjacent intake ports and two adjacent discharge / charge ports are spaced by the same distance DI that separates two adjacent intake and discharge / charge passages of the cylinder head and each intake port and each discharge / charge port has an opening section SI, identical to that of the intake and discharge / charge passages made in the cylinder head B.

[0271] As before, what matters is that the movement of the bars relative to the intake and discharge / charge passages of cylinder head B allows for selective opening / closing of the intake and discharge / charge passages.

[0272] It is understood that this embodiment is particularly advantageous, because the transition from one stage to the other requires the movement of only one of the two blades, which makes it fast, energy-efficient, reliable, because the bars move little in translation and only between two easily determined positions.

[0273] A person skilled in the art will adapt the settings (in particular the shape of the cams and the rotation speed of the camshafts) of the system according to the invention according to desired results, particularly in terms of compression ratio.

[0274] To adapt the cams to the different cycles of the air engine, it is possible, in particular, to create cams whose profile has several stages, based on the polar diagrams in Figures 9 to 14. Thus, a person skilled in the art could, for example, create a cam profile with three stages: - a first bearing, with the largest cam diameter (distance between the camshaft axis and the considered cam surface), whose function is to open the air passages 110 and 111 during the PHI phase of the engine cycle, - a second bearing, with the smallest cam diameter, opening access to air passages 401 and 402 during the PHC and PHD phases of the engine cycle, - a third bearing, with an intermediate cam diameter, whose function is to close access to all air passages outside the PHI, PHC and PHD phases of the engine cycle.

[0275] In the configuration described above, nothing would prevent, for example, the opening of the air charge / discharge passages from being configured so that these passages remain open during the engine's exhaust phase. Once charging is complete, the fact that the passages remain open does not negatively impact the system; the pressure in reservoir 500 will simply equalize with the exhaust pressure. An open exhaust during the discharge phase will simply delay the start of the discharge phase. This embodiment naturally extends to multi-blade engines.

[0276] Another possible adaptation allowing the cams to be adapted to the different cycles of the engine could consist of driving the cams at different speeds to ensure the opening sequence of the air passages of the air engine whose architecture would be similar to that shown in figures 16 to 21, where several blades are juxtaposed to give access to air passages for the injection of compressed air and the charging / discharging of an auxiliary air tank.

[0277] An example applied to the system shown in Figures 16 to 21 would be to rotate the cam associated with valve 20d at twice the speed of the cam associated with valve 20e, which rotates in phase with the engine. This embodiment can easily be extended to a larger number of juxtaposed blades. Indeed, as the number of juxtaposed blades increases, a simple sequencing solution consists of synchronizing the cams associated with the blades whose "rest" position opens the same air passages.

[0278] The drive of the camshaft(s) 52 can be achieved mechanically (see figures 22 to 24), by mechanical linkage to the engine shaft (crankshaft), or electronically (see figure 25), by linking the shaft or each shaft to an electric motor controlled electronically by a preset control unit or connected to one or more sensors in the car, in particular a piston position sensor.

[0279] The mechanical drive of the camshaft(s) 52-52a can be carried out as follows, in connection with figures 22 to 24.

[0280] A first solution for driving the cams 51 and 51a and the camshafts 52 and 52a is illustrated in Figure 22. This solution is mechanical, in the sense that it does not require any sensors or electronic control to drive the cams or the camshafts.

[0281] In this solution, the camshafts 52-52a are fixed to the axis of rotation of a pulley 53-53a. This pulley is connected to the crankshaft 54, which is fixed to the engine output shaft 55, by a belt 56-56a tensioned by tensioners 57-57a, as is conventionally known. The crankshaft 54 ​​has, for each piston, a crankpin 58 rotatably connected to a connecting rod 59, which is itself rotatably fixed to the cylinder 1. Thus, when the cylinder is pushed downwards by the air injection, the crankshaft is driven in rotation and generates a driving force that drives, in particular, the camshafts 52-52a through the rotation of the belt 56-56a and the pulleys 53-53a.

[0282] This pulley and belt transmission solution allows for synchronization of the operating cycles of the engine and the valves.

[0283] In the embodiment illustrated in Figure 22, if the pulleys 53-53a are of identical size, the camshafts 52-52a rotate in complete synchronization with the crankshaft. In this case, it is possible to modify the opening times of the leaf valves according to the invention by creating different profiles of the cams 51-51a. Alternatively, it is also possible to add clutch systems between the pulleys and the camshafts to control the cams according to a pre-programmed operating mode (mechanical or electronic).

[0284] A second mechanical drive solution for the camshafts 52-52a is illustrated in Figure 23. This solution uses a twin-shaft system: the camshaft 52-52a coupled with a splined shaft 60-60a by a gear 61-61a.

[0285] In this embodiment, a splined shaft 60-60a, whose spline arrangement 62-62a represents a "program" defined according to the desired position of the valve bar, is driven by the engine output shaft 55 via a belt 56-56o and pulley 53-53o transmission system. The splined shaft 60-60a in turn drives the camshaft 52-52a via a gear 61-61a which rotates according to the rhythm of the peaks and troughs defined by the splines 62-62a of the splined shaft 60-60a.

[0286] Figure 24 illustrates a projection of the lateral surface of the splined shaft 60, of the splines 62 defining peaks 63 and troughs 64 on the splined shaft where the gear would interact to drive the camshaft 52 according to a sequence designed to alternate the opening and closing phases of the blade 20d.

[0287] This embodiment allows for desynchronization of the cams with respect to the engine cycle and the cycle of the other cams. Furthermore, it is possible for a single splined shaft to drive several cams with different rhythms.

[0288] Thus, mechanically, we can precisely define the rotation of the cams and, consequently, the opening / closing of the different injection / charging / discharging passages of each valve.

[0289] In an alternative embodiment, the drive of the camshaft(s) 52-52a is carried out electronically as follows, in connection with Figure 25.

[0290] As shown in Figure 25, the camshafts 52-52a can be driven by electric motors 70-70a, advantageously equipped with a reducer and / or a multiplier 71-71a.

[0291] Each engine 70-70a is connected to a control unit 80 (engine computer) which can either be preprogrammed to set different but constant V52-V52a camshaft speeds 52-52a, or advantageously, be programmed to control the V52-V52a speed of the camshafts 52-52a of the different cylinders according to one or more signals transmitted by at least one sensor 90-91-92 of the vehicle.

[0292] Preferably, among these sensors, there is a position sensor 90 of the piston in the chamber, which allows for fine-tuning of the compressed air injection and the compressed air loading / unloading. Other sensors can be used so that the rotational speed V52 and V52a of the camshafts 52-52a is modulated to vary the volume of compressed air injected into the piston chamber, for example, according to the engine temperature, its operating speed, the rotational speed of the wheels (position sensor 91 of the throttle 91a), the required acceleration (position sensor 92 of the throttle 92a), the road gradient requiring a temporary power boost or, conversely, a power reduction, etc., must then be able to be controlled, for example, according to information obtained by sensors (see Figure 25).

[0293] Thus, the control unit directs the rotation of the camshafts 52-52a to move, during operation, the bar(s) 20d-20e to a position between an open position of the intake or discharge / charge passages and a closed position of the intake or discharge / charge passages. This figure is applicable to all embodiments of the invention described.

[0294] The control unit programmed in this way allows the injection of an optimal volume of air, at an optimal position of the piston, but also a variation of the volume of air injected according to needs, in particular according to the heat of the engine, its operating speed, the conformation of the road (uphill or downhill), etc.

[0295] Furthermore, the management, in the engine cycle, of the compressed air by the upward movement of the piston in the chamber, by partially discharging it and recharging it after the intake of compressed air, significantly improves the engine's power.

[0296] In general, the different embodiments of the invention make it possible to generate mechanical work similar to the known device in Figure 1, but with a much smaller quantity of air, and at a lower exhaust pressure, thus limiting engine fatigue.

[0297] Thus, figures 26, 27 and 28 illustrate the Clapeyron diagrams of a classic device of figure 1 (figure 26) and of a device according to the invention in motor drive mode (figure 27) and in post-motor brake mode (figure 28).

[0298] More specifically, Figure 26 illustrates the Clapeyron diagram of a classic piston engine, shown in Figure 1. In this figure as in Figures 27 and 28, the Volume variable, classically used in a Clapeyron diagram, is replaced by the Height of the chamber between the cylinder head and the piston, since the cross-section of the piston chamber is constant.

[0299] The diagram in Figure 26 can be read as follows:

[0300] At point 1, the piston is in its lowest position (BDC), so the chamber height is at its maximum. Outside air is admitted into the chamber at atmospheric pressure.

[0301] When the piston moves upwards, the height of the chamber decreases and the pressure of the air inside the chamber increases to reach point 2.

[0302] At this height, the piston encounters the valve head, lifts it, and opens the valve. The injection of compressed air immediately increases the pressure, bringing it to point 3. The piston continues to rise to top dead center, against the air pressure, so the system consumes work from point 3 to point 3*. Then the piston begins to descend until the valve closes (transition from point 3* to point 3), generating work that balances the work consumed by the piston to reach top dead center (transition from point 3 to point 3*). This balance of work consumed / work created is represented in the figure by a horizontal line between point 3 and point 3*, illustrating zero work.

[0303] From point 3, the compressed air continues to expand, pushing the piston back and generating work (the 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 decreases until the air escapes at point 4 through the exhaust outlet 12 of the chamber (see Figure 1).

[0304] The pressure therefore immediately drops to atmospheric pressure (point 5). The piston then descends further to its bottom dead center (point 1 of the diagram), allowing outside air to enter for a new cycle towards point 2.

[0305] Figure 27 illustrates the Clapeyron diagram of a mechanically injected engine according to the invention (solid line), of the discharge / charge type illustrated in Figures 9 to 21, in a motor drive mode. This mode is the most frequent operation and consists of driving the vehicle during acceleration or maintaining speed.

[0306] This diagram can be read as follows:

[0307] At this point, the piston is in its bottom dead center (BDC) position, so the chamber height is at its maximum. Outside air is admitted into the chamber at atmospheric pressure (H₁). a (dmission-PATM).

[0308] As the piston rises, the chamber height decreases and the air pressure within the chamber increases, reaching point 2a. Thanks to the relief / charge system, the relief / charge passages remain open for almost the entire upward stroke of the piston. The air above the piston exits the chamber, and the cylinder pressure is maintained at point 2a (compression pressure) as the piston continues its upward movement to point 2b. Since the pressure does not increase, the piston can rise higher and thus closer to its top dead center before air injection, so point 2b is shifted to the left on the graph compared to point 2 of the conventional engine (Figure 22).

[0309] At point 2b, the piston is therefore in the immediate vicinity of its top dead center and the valve is opened by the cam 51. The injection of compressed air immediately increases the pressure to reach point 3a.

[0310] The compressed air expands, pushing the piston back and generating work. The piston then begins to descend, and the compressed air inlet of the valve closes after an optimal volume of compressed air has been injected.

[0311] The air continues to expand and push the piston back to point 3b. At point 3b, the air that has been discharged into the buffer reservoir 500 is charged into the chamber by the opening of the discharge / charge passages, which increases the amount of air and the pressure in the chamber (Pcharge) compared to the conventional engine (see area W2b).

[0312] The air expands and the height of the chamber therefore increases until the air escapes, at point 4a, through the exhaust outlet of the chamber (identical to outlet 12 in Figure 1).

[0313] The pressure therefore immediately drops to atmospheric pressure (point 5a). The piston then descends further to its bottom dead center (point 1 of the diagram), allowing outside air to enter for a new cycle towards point 2a.

[0314] The Clapeyron diagram of figure 26 of the conventional engine is shown on figure 27 in dotted lines to illustrate the difference in work generated between the conventional injection system and the injection / discharge / charge system according to the invention.

[0315] In this figure, the white area W1 represents the work common to both devices. The dotted areas W2a-W2b represent the specific work of a device according to the invention in Figures 9 to 21, and the hatched area W3 represents the specific work of a conventional device in Figure 1.

[0316] In the case of a mechanical injection system according to the invention, it is observed that the work generated W2a+W2b is much greater than the work W3 generated by a conventional device.

[0317] The resulting power output is therefore much higher, while the air consumption of a device according to the invention is much lower than that of a conventional device. It should be noted that the discharge of air to the auxiliary reservoir 500 reduces the pressure in the cylinder at the moment the compressed air is injected. The injection pressure is therefore lower, and so is the quantity of air.

[0318] Thus, thanks to delayed injection (i.e. as close as possible to top dead center by the discharge mechanism), it is possible to inject compressed air at a low pressure from 15 bar (compared to at least 30 in the standard engine in Figure 1), which limits the fatigue of the parts.

[0319] Furthermore, in a motor drive operation, the discharge / charge avoids an excessive compression pressure and promotes a more “complete” (isothermal) expansion of the air by restoring a portion of the work that would have been lost during the compression phase if there had been no discharge of the air and an increase in the pressure of the compressed air above the piston.

[0320] Figure 28 illustrates the Clapeyron diagram of a mechanically injected engine according to the invention (solid line), of the discharge / charge type illustrated in Figures 9 to 21, in a post-engine-braking mode. This mode is a less frequent operating condition and consists of using recovered air when the vehicle slows down without braking, i.e., through engine braking.

[0321] During this phase, the engine is driven by the wheels, which slow down. In the cylinders, the compressed air injection passages remain closed because the accelerator pedal is released. Simultaneously, the discharge / charge passages are controlled to open only during the discharge phase (Figures 9 and 16) in order to fill the buffer reservoir 500 with compressed air at pressures comparable to the engine's operating compressed air pressure.

[0322] As a note, in electrical generator type applications, during a sharp drop in electrical power demand, in order not to lose the compressed air that has been injected, the discharge / charge passages can be opened before the end of the expansion phase (from HPMH to H exhaust) so that the air can be discharged into the buffer reservoir 500 and stored there.

[0323] Once the engine braking deceleration phase is over, when acceleration or maintaining speed is required by pressing the accelerator pedal, the compressed air stored in the buffer reserve 500 according to the operating mode described previously can be used in a post-engine braking mode, the diagram of which is illustrated in Figure 28, and which allows even more efficient cycles depending on the pressure and the quantity of air stored in the buffer reserve 500.

[0324] This diagram can be read as follows:

[0325] At this point, the piston is in its bottom dead center (BDC) position, so the chamber height is at its maximum. Outside air is admitted into the chamber at atmospheric pressure (H₁). a (dmission-PATM).

[0326] As the piston rises, the chamber height decreases and the air pressure within the chamber increases, reaching point 2c. Since the 500 buffer reservoir of the discharge / charge system is full, the discharge / charge passages remain closed. Therefore, the air above the piston does not escape the chamber, so the pressure in the chamber when it reaches point 2c is higher than during normal operation in motor drive mode (see point 2a in Figure 27). Consequently, point 2c is shifted to the left and upwards on the graph compared to point 2b in motor drive mode (Figure 27).

[0327] At point 2c, the piston is therefore in the immediate vicinity of its top dead center and the valve is opened by the cam 51. The injection of compressed air immediately increases the pressure to reach point 3a.

[0328] The compressed air expands, pushing the piston back and generating work. The piston then begins its downward movement, and the compressed air inlet valve closes after an optimal volume of compressed air has been injected. At point 3c, compressed air, which was discharged and accumulated in the buffer reservoir 500 during engine braking, is charged into the chamber through the opening of the discharge / charge passages. This explains the excess pressure in the chamber (Pcharge) compared to a conventional engine. In a first variant, the charge / discharge passages remain open, and all the air stored in the buffer reservoir 500 is charged into the piston in a single cycle. Alternatively, in a second variant, the charge / discharge passages are closed after only a portion of the air stored in the buffer tank is charged into the chamber, allowing the compressed air accumulated in the buffer tank to be charged for a few cycles before returning to normal engine drive operation. It is understood that such operation is only possible if the cam actuators can be controlled independently of the engine cycle.

[0329] Once compressed air is charged into the chamber, the air continues to expand within the chamber and push back the piston. The height of the chamber therefore increases and the pressure inside the chamber decreases until the air escapes, at point 4a, through the chamber's exhaust outlet (identical to outlet 12 in Figure 1).

[0330] The pressure therefore immediately drops to atmospheric pressure (point 5a). The piston then descends further to its bottom dead center (point 1 of the diagram), allowing outside air to enter for a new cycle towards point 2c.

[0331] The Clapeyron diagram of figure 24 of the conventional engine is shown on figure 28 in dotted lines to illustrate the difference in work generated between the conventional injection system and the injection / discharge / charge system according to the invention.

[0332] In this figure, the white area W1 represents the work common to both devices. The dotted areas W2c and W2d represent the specific work of a device according to the invention of Figures 9 to 21, and the hatched area W3 represents the specific work of a conventional device of Figure 1.

[0333] In the case of a mechanical injection system according to the invention in post-engine braking mode, it is observed that the work generated W2 is once again much greater than the work W3 generated by a conventional device. Furthermore, it is better distributed over the height of the chamber (see the areas at points W2c and W2d).

[0334] The resulting power output is therefore much higher, while the air consumption of a device according to the invention is much lower than that of a conventional device. It should be noted that in this operating mode, the air discharge allows for the recovery of significant pressure during regenerative braking or during a sharp drop in engine power demand. The injection pressure is therefore lower, and so is the quantity of air.

[0335] Finally, thanks to delayed injection (i.e. as close as possible to top dead center by the discharge mechanism), it is possible to inject compressed air at a low pressure from 15 bar (compared to at least 30 in the standard engine in Figure 1), which limits the fatigue of the parts.

[0336] The entire process and device can also or alternatively be used for exhaust within the framework of a conventional cylinder.

[0337] The invention therefore also relates to an engine comprising a cylinder head equipped with a device according to one of the three embodiments of figures 2 and 3, 4 to 6, and 7 and 8, and capable of implementing a delayed injection of compressed air into the piston chamber.

[0338] Preferably, the invention also relates to an engine comprising a cylinder head equipped with a device according to one of the three embodiments of figures 9 to 14, 15 and 16 to 21, and capable of managing compressed air according to the method according to the invention.

Claims

Demands

1. A mechanical compressed air injection device for equipping a cylinder head (B) of a compressed air engine, which also includes at least one piston (1) for moving in a chamber (5), the cylinder head (B) being internally traversed by an intake duct (11) comprising at least one intake passage (110, 111, 112, 113, 114) substantially parallel to the direction of compressed air injection into the piston chamber (5) and by at least one channel (13) perpendicular and transverse to said at least one intake passage, 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 operating position in the engine, and comprising: a bar (20) arranged to slide within said at least one channel (13), said bar (20) comprising a first portion (21) provided with at least one inlet orifice (210, 211, 212, 213, 214), and a second position control portion (22), the valve further comprising, a means of recalling (40) the bar (20) and, a cam actuator (50) configured to control the movement, during operation, of the bar (20) in a position between an opening position of said at least one inlet passage (110, 111, 112, 113, 114) in which said at least one inlet orifice (210, 211, 212, 213, 214) carried by the first part (21) is fully aligned with said at least one intake passage (110, 111, 112, 113, 114), and a closing position of said at least one intake passage (110, 111, 112, 113, 114) of the intake valve in which said at least one intake orifice (210, 211, 212, 213, 214) carried by the first part (21) is entirely offset from said at least one intake passage (110, 111, 112, 113, 114).

2. Device according to claim 1, characterized in that the cylinder head (B) is internally traversed by a plurality of intake passages (110-114) of determined opening section, the intake passages being spaced a determined distance (DI), and in that the channel (13) is perpendicular and transverse to all the intake passages, the first part (21) of the bar (20) comprising as many intake orifices (210-214) as the cylinder head (B) comprises compressed air intake passages, the intake orifices being spaced the same distance (DI) as the intake passages.

3. A device according to claim 2, wherein the valve (S') comprises another bar (20a) slidably arranged in said at least one channel (13), this other bar (20a) comprising a first portion (21a) having as many inlet ports (210a, 21a, 212a, 213a, 214a) as the cylinder head (B) has compressed air inlet passages, the inlet ports (210a, 21a, 212a, 213a, 214a) being spaced the same distance (DI) apart as the inlet passages, and a second position control portion (22a), the two bars (20, 20a) being arranged end-to-end, the valve (S') further comprising a return means (40a) for the other bar (20a) and another cam actuator (50) configured to control the movement, during operation, of the other bar (20a) in a position between an open position of the intake passages (110, 111, 112, 113, 114) in which the intake ports (210a, 211a, 212a, 213a,214a) carried by the other bar (20a) are fully aligned with the intake ports (110, 111, 112, 113, 114), and a closed position in which the intake ports (210a, 211a, 212a, 213a, 214a) carried by the other bar (20a) are fully offset from the intake ports (110, 111, 112, 113, 114).

4. Device according to any one of the preceding claims, characterized in that it is further configured to cooperate with a compressed air discharge / charge duct (400) from the cylinder head, this discharge / charge duct (400) comprising at least one discharge / charge passage (401, 402, 403, 404, 405) traversed perpendicularly and transversely by a channel (13b) arranged next to the channel (13) receiving the inlet valve (601), and in that the device further comprises a discharge / charge valve (602) arranged next to the inlet valve (601), and comprising: a bar (20c) arranged slidably in said channel (13b), said bar (20c) comprising a first part (21) provided with at least one discharge / charge orifice (410, 411, 412, 413, 414), and a second part (22) for position control, the valve (602) including, in addition, a means of recalling (40) the bar (20c) and, a cam actuator (50) configured to control the movement, during operation, of the bar (20c) in a position between an open position of said at least one discharge / charge passage (401, 402, 403, 404, 405) in which said at least one discharge / charge orifice (410, 411, 412, 413, 414) carried by the first part (21) is fully aligned with said at least one discharge / charge passage (401, 402, 403, 404, 405), and a closed position of said at least one discharge / charge passage (401, 402, 403, 404, 405) of the intake valve in which said at least one discharge / charge orifice (410, 411, 412, 413, 414) carried by the first part (21) ) is entirely offset from audit at least one discharge / charge passage (401, 402, 403, 404, 405).

5. Device according to claim 2, characterized in that it is further configured to cooperate with a compressed air discharge / charge duct (400) of the cylinder head, said discharge / charge duct (400) comprising at least one discharge / charge passage (401, 402) traversed perpendicularly and transversely by the channel (13), and in that the first portion (21) of the bar (20) further comprises at least one discharge / charge orifice (410, 411) intended to align, in operation, with said at least one discharge / charge passage (401, 402) of the discharge / charge duct (400), the inlet orifices (110, 111) and the discharge / charge orifices (410, 411) being arranged on the first portion (21) of the bar (20) such that, in operation, the bar (20) is moved to a position between: the opening position of the inlet passage (110, 111), in which said at least one inlet orifice (210, 211) carried by the first part (21) of the bar (20) is fully aligned with said at least one inlet orifice (110, 111), while said at least one discharge / charge orifice (410, 411) carried by the first part (21) of the bar (20) is fully offset from said at least one discharge / charge passage (401, 402); the "closed" position of said at least one inlet passage (110, 111) and said at least one discharge / charge passage (401, 402), wherein said at least one inlet orifice (210, 211) carried by the first portion (21) of the bar (20) is entirely offset from said at least one inlet passage (110, 111), and said at least one discharge / charge orifice (410, 411) carried by the first portion (21) of the bar (20) is entirely offset from said at least one discharge / charge passage (401, 402); and a compressed air discharge / charge position in which said at least one inlet passage (110, 111) is closed and said at least one discharge / charge passage (401, 402) is open, said at least one inlet orifice (210, 211) carried by the first part (21) of the bar (20) being entirely offset from said at least one inlet passage (110, 111), and said at least one discharge / charge orifice (410, 411) carried by the first part (21) of the bar (20) being entirely aligned with said at least one discharge / charge passage (401, 402); the closing position being intermediate, in the movement of the bar, between the opening position and the unloading / loading position.

6. A device according to claim 3, characterized in that it is further configured to cooperate with a compressed air discharge / charge duct (400) of the cylinder head, this discharge / charge duct (400) comprising at least one discharge / charge passage (401, 402) traversed perpendicularly and transversely by the channel (13), and in that the first portion (21) of each bar (20d, 20e) further comprises as many discharge / charge ports (410, 411) as the discharge / charge duct (400) comprises discharge / charge passages (401, 402), the inlet ports (110, 111) and the discharge / charge ports (410, 411) being arranged on the first portion (21) of each bar (20d, 20e) such that, in operation, each bar (20d, 20e) is moved between two usage positions: A simultaneous position (PSO) of opening the inlet passage (110, 111) and closing the discharge / charge passage (401, 402), wherein each inlet port (210a, 211a, 210b, 211b) carried by the first portion (21) of each bar (20d-20e) is fully aligned with said at least one corresponding inlet passage (110, 111), while each discharge / charge port (410a, 411a, 410b, 411b) carried by the first portion (21) of each bar (20d-20e) is fully offset from said at least one corresponding discharge / charge passage (401, 402); and A simultaneous position (PSF) of closing said at least one inlet passage (110, 111) and opening said at least one discharge / charge passage (401, 402), wherein each inlet port (210a, 21la, 210b, 211b) carried by the first part (21) of each bar (20d-20e) is entirely offset from said corresponding at least one inlet passage (110, 111), and each discharge / charge port (410a, 41la, 410b, 411b) carried by the first part (21) of each bar (20d-20e) is entirely aligned with said corresponding at least one discharge / charge passage (401, 402).

7. A device according to any one of claims 1 to 6, wherein the cam actuator (50) comprises at least one cam (51) fixed to a camshaft (52), and is configured to directly control the movement of the bar, at least one cam (51) fixed to the camshaft (52) being, in operation, bearing against a free end of the second valve position control portion (22), the return means (40) being configured such that the free end of the second control portion (22) follows the cam (51) when the latter is rotated by the camshaft (52), the cam (51) being configured to move, in operation, the bar (20) to a position between the open and closed positions of said at least one intake passage (110, 111, 112, 113, 114) and, where applicable, of said at the less one discharge / charge passage (401, 402).

8. Device according to any one of claims 1 to 6, wherein the free end of the second position control part (22, 22a) of the bar or each bar (20, 20a) has a follower roller intended to be in contact with the cam.

9. Device according to any one of claims 1 to 6, wherein the cam actuator (50) is configured to indirectly control the movement of the bar during operation, the valve comprising a pneumatic actuator (V) connected to a pneumatic source of compressed air (R) having an opening / closing mechanism connected to the cam actuator (50).

10. Cylinder head of compressed air engine equipped with at least one injection device according to any one of claims 1 to 9, internally traversed by at least one intake passage (110) substantially parallel to the direction of injection of compressed air into the chamber (5) of the piston and by at least one channel (13) perpendicular and transverse to said passage, and further comprising a support for a cam actuator (50) configured to control the displacement, in operation, of the bar (20) of the or each mechanical compressed air injection device.

11. Cylinder head according to claim 10, further traversed internally by at least one discharge / charge passage (401, 402) substantially parallel to the direction of injection of compressed air into the chamber (5) of the piston and by a channel (13b) perpendicular and transverse to said passage.

12. Cylinder head of compressed air engine equipped with an injection device according to claim 10 or 11, internally traversed by a plurality of intake passages (110, 111, 112, 113, 114) of determined opening area, and substantially parallel to the direction of injection of the compressed air into the chamber (5) of the piston, the intake passages being spaced by a determined distance (DI) greater than or equal to the opening area of ​​the intake passages, and by at least one channel (13) perpendicular and transverse to all the intake passages.

13. Cylinder head according to claim 12, further traversed internally by a plurality of discharge / charge passages (401, 402) of determined opening area, and substantially parallel to the direction of injection of the compressed air into the chamber (5) of the piston, the discharge / charge passages (401, 402) being spaced at a determined distance (DI) greater than or equal to the opening area of ​​the intake passages, and by at least one channel (13) perpendicular and transverse to all the intake passages.

14. Cylinder head according to claim 12, further traversed internally by a plurality of discharge / charge passages (401, 402) of opening section identical to the opening section of the intake passages (110, 111, 112, 113, 114), and substantially parallel to the direction of injection of the compressed air into the chamber (5) of the piston, the intake passages (110, 111, 112, 113, 114) and the discharge / charge passages (401, 402) being spaced at a determined distance (DI) greater than or equal to twice the opening section of the intake passages.

15. Compressed air engine comprising a cylinder head according to any one of claims 10 to 14.

16. Hybrid drive system for equipping a vehicle comprising a high-pressure compressed air tank connected to a compressed air piston engine according to claim 15, in contact with an electric generator to generate electricity when driven by the compressed air piston engine, the electric generator being connected to at least one electric motor itself connected to a transmission in contact with a vehicle propulsion component.

17. Drive chain according to claim 16, wherein 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).

18. Drive chain according to claim 17, further comprising a throttle control movable between a stop position and a maximum acceleration position and connected to an electronic control circuit comprising a controller programmed to supply the electric motor from the electrical relay reserve according to a signal received by at least one sensor fitted to the vehicle.

19. Generator set comprising a high-pressure compressed air tank connected to a compressed air piston engine according to claim 15, coupled with an electric generator to generate electricity when driven by the compressed air piston engine.

20. A method for managing air in a drive chain equipped with a main compressed air tank and a compressed air motor according to claim 15, comprising: an engine block comprising N cylinders, N being an integer greater than or equal to 1, each cylinder having a chamber and a piston mounted to move in translation within said chamber between a high position called "top dead center" and a low position called "bottom dead center", the chamber comprising an exhaust outlet; and a cylinder head associated with the engine block and capable of closing the chamber or each chamber, the cylinder head comprising, for each chamber at least one compressed air intake valve, and a relief / charge valve; the process being characterized in that it comprises the following successive steps, for each cylinder: 1) Compression by the piston of the air present in the chamber; 2) Discharge of the compressed air from the chamber to a buffer reservoir through the relief / charge valve; 3) Compressed air intake into the piston chamber from the 80 / 81 main reservoir via the intake valve; 4) Charge of the air stored in the buffer reservoir to the piston chamber through the discharge / charge valve; 5) Exhaust of the expanded air from the piston chamber to the outside through the exhaust outlet.

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