BR112013015180B1 - engine manufacturing method - Google Patents

Abstract

METHOD OF MANUFACTURING AN ENGINE A free piston engine generator comprising a motor cylinder, a piston configured to move within the cylinder, a cylinder holder having an internal perforation to receive the motor cylinder and a plurality of magnetizable elements arranged inside the cylinder support to be adjacent to the cylinder over at least a part of its extension.

Description

The present invention relates to a free piston engine generator and a method of manufacturing an engine generator. In particular, the present invention relates to a free piston engine generator that has a construction arranged to optimize the efficiency of the generator and to provide good control of the piston position and movement of the piston by the generator.

Electric energy can be generated using a linear generator coupled to a free piston motor, in which the linear movement of the reciprocating piston by means of one or more electric coils generates changes in the magnetic flux, as revealed in document US-B-7318506, for example. As the piston moves inside the cylinder in addition to the coils, it interacts with an alternating magnetic flux within the stators to generate electrical energy that can be used for useful operation or stored for later use.

However, the efficiency of this electric power generation system is highly dependent on the thickness of the cylinder wall and the proximity of the electric power generating elements to the reciprocating piston inside the engine cylinder.

According to the present invention, a free piston engine generator comprising a motor cylinder, a piston configured to move within the cylinder, is provided with a cylinder holder having an internal perforation to receive the motor cylinder and a plurality of magnetizable elements disposed within the cylinder support to be adjacent to the cylinder over at least a part of its extension.

In the present invention, the particular arrangement of the cylinder support that allows the plurality of magnetizable elements to be positioned adjacent to the cylinder optimizes the efficiency of the free piston engine generator and provides good control of the piston position and movement of the piston by the generator.

Preferably, the cylinder support has one or more recesses that allow the plurality of magnetizable elements to be positioned adjacent to the cylinder. Preferably, the magnetizable elements are «positioned in direct physical contact with the cylinder. Preferably, one or more of the magnetizable elements act as a stator in the generator. 4- Preferably, the cylinder is fixed inside the cylinder holder by an adhesive that provides thermal insulation between the cylinder and the cylinder holder.

Preferably, the cylinder support comprises a plurality of elements that are coaxially mounted on the cylinder. Preferably, the cylinder support includes cooling means for cooling the cylinder.

Preferably, the cylinder has a wall thickness that is less than 5% of the inner diameter of the cylinder, where the wall thickness is typically less than about 2 mm. Preferably, the piston comprises central, magnetizable, laminated elements and non-magnetizable spacer elements. Preferably, the intake means and are located in a central position along the cylinder, which simplifies the arrangement of the engine and makes this arrangement more compact by allowing a common intake means 30 to supply fluid to each combustion chamber.

In addition, by positioning the intake means in a position removed from the exhaust valve, the renewal of the flared gases can be greatly enhanced by the unidirectional renewal flow provided within each combustion chamber, which in turn results in efficiency improved, reduced unburned fuel hydrocarbons and lower costs.

Preferably, the ingestion means comprise both an air ingestion and a fuel injection means, so that fuel injection into a combustion chamber can occur during the intake air intake. The intake means may also comprise a plurality of air intake means and at least one fuel injection means. The provision of air intake means and fuel injection means together in the intake means allows both of these aspects to share a common sliding gate valve, each being in recess within the void behind the sliding gate valve. This results in a simpler and therefore cheaper construction.

Preferably, the air intake means comprises a sliding gate valve and a secondary valve 20, such as a solenoid trigger valve, barrel valve or other valve means arranged in series with the sliding gate valve. The secondary valve can allow air in the chamber at any time, when the sliding gate valve is not covered by the piston, which allows good control of the expansion ratio in response to a combustion event, regardless of the piston position within the limits defined by the opening and closing positions of the sliding gate valve.

Preferably, the fuel injection means 30 comprises two injectors arranged on each side of the secondary air intake valve to allow fuel to be injected directly into the respective chamber, regardless of whether the secondary intake valve is open or closed. The injectors are, ideally, piezo injectors, which allow the electronic activation and low cost and control of the fuel injection.

Preferably, the fuel injection means 5 is configured to inject fuel just before the closing of the slide valve, to ensure that the injected fuel cannot be transported in and out of the exhaust port when renewing the air intake load before the exhaust valve is closed, reducing 10 hydrocarbon emissions.

Preferably, ignition means 4 are provided in each chamber to start combustion of the mixture of compressed air and fuel. The use of spark ignition fuels and their related operating cycles generates 15 inherently less particulate emissions than fuels and compression ignition cycles.

Preferably, an exhaust means is provided in each combustion chamber to allow the flared gases to be exhausted from the chamber after combustion.

Preferably, the exhaust medium is a solenoid trigger valve provided in each combustion chamber, with the valves being coaxial with the cylinder, so that the area of limitation in the exhaust flow can approach 40% of the section area of internal cylinder perforation, reducing the back pressure of the exhaust gas during exhaustion and renewal.

Preferably, the cylinder has a length at least ten times its diameter, which provides reduced variability of the compression ratio in each 30 cycle, resulting from a low rate of change in the compression ratio with piston displacement error in neutral higher.

Preferably, the piston is configured to be elongated and the engine cylinder has a dimensioned internal perforation, so that a compression ratio between 10: 1 and 16: 1 can be achieved. This is the maximum that can be achieved in a conventional spark ignition engine due to detonation (strike). Preferably, the engine is a 'flex fuel' engine that operates on any mixture of gasoline, anhydrous ethanol and hydrous ethanol. The compression ratio can be optimized by the engine management system, according to the particular ethanol / gasoline / water mixture that is used.

Also, an expansion ratio twice as large as the compression ratio is obtained. A long expansion stroke allows more of the combustion energy to be transferred to the piston and, in addition, allows more time for control (ie, to react to the measured piston speed variability).

Preferably, the ingestion means are positioned at an appropriate distance from the exhaust valve to ensure that a compression ratio of between 10: 1 and 20 16: 1 is achieved.

In accordance with the present invention, a method of manufacturing an engine generator is provided, comprising the provision of a cylinder configured to accommodate at least one piston that is free to reciprocate within the cylinder, 25 fixing the cylinder within a bearing support. cylinder having an internal perforation arranged to receive and provide structural support for the cylinder and arrangement of a plurality of magnetizable elements adjacent to the cylinder, so that when the piston moves within the cylinder, it induces the magnetic flux as passes the plurality of magnetizable elements. Preferably, one or more recesses in the cylinder support are provided to receive the plurality of magnetizable elements.

Preferably, one or more sections of the cylinder support along the extension of the cylinder are removed to expose one or more sections of the cylinder wall and the plurality of magnetizable elements is disposed within the recesses, so that it is in direct physical contact with the cylinder wall.

According to the present invention, a method of manufacturing an engine is also provided, comprising providing a cylinder configured to accommodate at least one piston that is free to reciprocate within the cylinder, extruding a cylinder support that is arranged to retain and providing structural support for the cylinder, and fixing the cylinder within the cylinder support, so that the cylinder wall is reinforced by the structure of the cylinder support.

Preferably, the plurality of magnetizable elements is arranged to provide support that supports the cylinder. Preferably, the magnetizable elements are arranged to provide a force in relation to the cylinder wall, for example, they can be polarized in relation to the cylinder wall, or they can be preloaded, so that they apply a force in relation to the wall of the cylinder when positioned adjacent to it.

Preferably, the cylinder is affixed within the cylinder holder using an adhesive material on the outside of the cylinder, where the adhesive material provides thermal insulation between the cylinder and the cylinder holder.

Preferably, the cylinder support is provided with a cooling medium to cool the cylinder.

Preferably, the inner wall of the cylinder is coated with a friction reducing material to reduce friction between the inner wall and a piston that passes along it.

Preferably, the thickness of the cylinder wall is less than 5% of the inner diameter of the cylinder, where the thickness of the cylinder wall is typically less than 5 about 2 mm. In accordance with the present invention, a vehicle is provided having a free piston engine generator, as described above.

The construction of the engine generator of the present invention provides several important advantages over the construction of a typical free piston engine generator, in which two cylinder heads are affixed to two cylinders, with a separate electrical machine set, located axially between the cylinders.

The cylinder support is preferably formed by extrusion of a ductile material, such as aluminum alloy. Advantageously, the elongated construction allows the use of extrusion manufacturing technology to form the cylinder holder, rather than extensive CNC molding or machinery technology used for conventional engines. Extrusion offers faster manufacturing cycle time and greater tolerances before machining operations than molding, reducing the cost of the finished part. Similarly, the cylinder may be formed from low-cost tube forming fabrication technologies or other consolidation. This construction therefore reduces the overall cost of the engine cylinder assembly.

In addition, the contiguous shape of the cylinder support, which remains unbroken along the middle section 30 of the engine, ensures that both combustion chambers are coaxially aligned with high precision and provides a continuous support surface for the piston to travel along. her. This allows the piston to move back and forth from a centrally arranged intake, as described here, while minimizing the amount of wear to the cylinder's internal surface during the engine generator's operating life.

Although the cylinder support is preferably a single extruded element, it could alternatively be formed by coaxially assembling a pile of different extruded elements in a common cylinder. For example, two extrusions can be placed on both sides of the ingestion means, where the extrusions are mounted coaxially on the cylinder.

Ideally, the extrusion cylinder support wall should be thick and / or strong enough, that is, support the load to allow a much thinner cylinder wall 15 to provide wear and sealing surfaces than it would otherwise be. way, necessary. The cylinder holder ideally has sections of material removed along the length of the cylinder to form one or more recesses that, ideally, expose the cylinder wall within it. The 20 recesses are formed through the cylinder support, preferably extending from the outer surface inwards, so that the recesses open outwards. A plurality of magnetizable elements can be positioned in strict proximity to the cylinder, by arranging it in one or more 25 recesses, each magnetizable element preferably fixed directly to the cylinder wall, which separates them from the magnetic circuit elements of the piston movement.

The size of the cylinder wall thickness is an important determinant of the efficiency of the electric machine, and 30 must be as small as possible for high efficiency. By providing adequate load-bearing power using the cylinder support and magnetizable stator elements, the cylinder wall is not required to withstand cylinder fluid pressures and can be made considerably thinner, subject to manufacturing, assembly and wear restrictions.

The inner and outer surfaces of the cylinder provide substrates for wear and thermal coatings 5 respectively. A thermal coating can be applied to the outer surface of the cylinder in the form of an adhesive material to provide secure, insulating load support connection between the cylinder and the cylinder support.

In addition, the fixing arrangement of a cylinder 10 within the cylinder holder provides the advantage that the mating surfaces of the respective components need not be finished in any particular pattern, rather than allowing the cylinder to be fitted within the cylinder holder .

A free piston engine generator according to the present invention has several applications. For example, it can be integrated into a series hybrid electric vehicle power train that incorporates temporary electrical energy storage and one or more drive motors 20 suitable for use as an automotive power source in small passenger vehicles, where the electrical energy generated by the free piston engine is accumulated in an electrical energy storage device integrated into the vehicle to be released to the vehicle's drive engines on demand.

As a power source for a small passenger car, the present invention preferably runs on a spark-ignited two-stroke engine cycle, with four cylinders being arranged in a planar configuration so that the engine can be mounted transverse below from the front and rear seats of the vehicle, offering significantly more design flexibility to the layout of the passenger and storage spaces compared to a conventional internal combustion engine.

Each cylinder includes a free piston, whose movement induces electrical energy in a linear generator arranged around each cylinder, and whose movement is controllable by several means, including valve timing and ignition events and by modulating the energy extracted or supplied piston in each stroke. The movement of the pistons is synchronized, so that the engine is completely balanced, where the piston, ideally, 10 comprises alternating magnetizable elements and non-magnetizable spacer elements.

In addition, each cylinder is loaded by means of a intake mechanism that introduces fluid into the cylinder at a distal position from each end of the cylinder. The intake mechanism includes a trigger valve and sliding gate valve in series, so that timing of intake flow events can be controlled independently of the piston positions in relation to the cylinders. The exhaust gas leaves the cylinders of the 20 exhaust valve mechanisms located at the end of each cylinder.

The cylinder geometry and arrangement of the intake and exhaust mechanisms are such that the exhaust renovation is completed with limited mixing between the intake fluid and the exhaust fluid. The geometry of the combustion chamber offers a ratio of area to low surface volume and low conductivity materials are used in the piston crown and piston head, so that minimal heat is rejected from the engine. The geometry of the cylinder and piston provides an expansion ratio that is at least twice the compression ratio.

The layout and number of cylinders used are, however, dependent on the application and the engine operating cycle can also be varied for different applications, for example: internal ignition combustion by spark; internal combustion ignition by homogeneous charge compression; and compression ignition of heterogeneous charge. Some aspects of the present invention can also be performed within an external combustion cycle. Examples of external combustion cycle embodiments include use of the present invention as a gas expander for fluid from a gas turbine exhaust, an organic rankine cycle or a Stirling cycle. In a Stirling engine, heat from an external combustion source is supplied to the chamber containing operating fluid compressed at the upper dead center. After expansion, the exhaust gases are expelled to a closed cooling chamber before being readmitted to the chamber through the ingested means in a closed circuit.

The fuel, in several alternative embodiments, can be hydrated ethanol, mixtures of anhydrous ethanol-gasoline, or gasoline. The invention can also be carried out using diesel, bio-diesel, methane (CNG, LNG or biogas) or other gaseous or liquid fuels. In an external combustion embodiment, a wide range of fuels can be used.

Likewise, in conjunction with an energy storage system to provide temporary peak power output requirements, the present invention provides a low cost, high efficiency power supply for small passenger car applications, and many others. applications in which low cost and high efficiency are major design considerations, for example, as a static power generator for distributed power generation.

An example of the present invention will now be described, with reference to the accompanying figures, in which: Figure 1 shows a longitudinal section through a cylinder having a piston, according to an example of the present invention; Figure 2 is a longitudinal section through the piston, showing the construction of planar elements; Figure 3 is a cross-section through the piston, showing the concentric arrangement of the axis and planar elements; Figure 4 is a sectional view of the cylinder of Figure 3 illustrating the magnetic flux in alternating stator elements caused by the movement of the piston according to the present invention; Figure 5a is a cross-section through a cylinder showing the linear generator stator and the magnetic circuit formed by a permeable element in the first piston; Figure 5b is a cross-section of an alternative generator stator arrangement for two adjacent cylinders, in which the linear generator stator and the magnetic circuit are formed by a permeable element in the first piston; Figure 6 is a partial sectional view of the cylinder illustrating its construction; Figure 7 is a more detailed longitudinal section 25 of the arrangement of the intake trigger valve, intake port valve and fuel injector during the intake load displacement renewal phase; Figure 8 is a more detailed longitudinal section of the exhaust medium including the exhaust trigger valve and actuator during the exhaust phase; Figure 9 is a graph of displacement and time that shows the change in the position of the piston inside a cylinder during a complete engine cycle, and the timing of the engine cycle events during that period; Figure 9a is a table showing different means of controlling the compression ratio that can be used to control the compression ratio in a typical engine cycle; Figure 9b is a flow chart corresponding to the table in Figure 9a; Figure 10 is a pressure and volume graph which shows a typical cylinder pressure graph over a complete engine cycle; Figure 11 is a schematic longitudinal section through a cylinder in the upper dead center, at the end of the compression phase and close to the moment of spark ignition and the beginning of the combustion event in the first chamber; Figure 12 is a schematic longitudinal section through a cylinder in the middle of the expansion phase of the first chamber; Figure 13 is a schematic longitudinal section 20 through a cylinder at the end of the expansion phase, but before the intake trigger valve opens; Figure 14 is a schematic longitudinal section through a cylinder after opening the intake trigger valve to charge chamber 1, allowing the intake charge fluid pressure to equalize the lower cylinder pressure in the first chamber; Figure 15 is a longitudinal-schematic section through a cylinder, after opening the exhaust trigger valve, and while the intake trigger valve 30 remains open, evacuating the first chamber; Figure 16 is a schematic longitudinal section through a cylinder during fuel injection in the first chamber, after the intake trigger valve has closed; Figure 17 is a schematic longitudinal section through a cylinder during injection of lubricant on the external surface of the piston; Figure 18 is a schematic longitudinal section through a cylinder while the exhaust trigger valve is open, and after the intake trigger valve and sliding gate valve have closed, so that the exhaust expulsion of the first exhaust gases continues. chamber 10 is reached by displacing the piston; Figure 19 is a schematic longitudinal section through a cylinder in the middle of the compression phase in the first chamber; Figures 20A and 20B show a section of a cylinder holder of an engine generator, according to the present invention, with (A) and without (B) the affixed electrical machine; Figure 20C shows a perpendicular section of an engine generator cylinder holder through the X-X plane shown in Figure 20A; Figure 21 is a schematic perpendicular section of a four-cylinder engine construction through the intake means including the electric charge compressor; Figure 22 is a schematic perpendicular section 25 of a four-cylinder engine construction through the electrical generating means; and Figure 23 is a schematic perpendicular section of a four-cylinder engine construction through the exhaust medium.

Figure 1 shows an example of an engine, according to the present invention, comprising a hollow linear cylinder 1. A piston 2 is provided inside the cylinder 1, the piston 2 having a constant diameter that is configured to be slightly smaller than the internal diameter of cylinder 1, but only to the extent that piston 2 is free to move along the extension of cylinder 1. The piston 2 is otherwise restricted in coaxial alignment with cylinder 1, thereby dividing , efficiently cylinder 1 in a first combustion chamber 3 and a second combustion chamber 4, each chamber having a variable volume depending on the position of piston 2 within cylinder 1. No part of piston 2 extends outside the cylinder 1. Using the first chamber 3 as an example, each of the chambers 3, 4 has a variable height 3a and a fixed diameter 3b.

Cylinder 1 is preferably symmetrically rotatable about its axis and symmetrical about a central plane perpendicular to that axis. Although other geometric shapes 15 may possibly be used to carry out the invention, for example, having pistons of square or rectangular section, the arrangement having pistons of circular section is preferred. The cylinder 1 has a series of openings 1, 1b provided along its length and distal from the 20 ends, preferably in a central location.

Through the movement of the piston 2, the openings la, lb form a sliding door intake valve 6a, which is arranged to operate in conjunction with an air intake 6b provided around at least part of the cylinder 1, as is 25 described in detail below.

Cylinder 1 preferably has an extension at least ten times its diameter to provide reduced variability of the compression ratio in each cycle, as the result of a low rate of change of the compression ratio with piston displacement error in neutral higher.

Figure 2 shows a piston 2 having an outer surface 2a and comprising a central axis 2c on which a series of cylindrical elements are mounted. Such cylindrical elements may include a piston crown 2d at each end of the central axis 2c, each piston crown 2d preferably constructed of an insulating and temperature-resistant material such as ceramic. The end surface of the piston crown 2b is preferably slightly concave, reducing the proportions of area to volume of the surface of the first and second chamber 3, 4 in the upper dead center and thereby reducing heat losses. In fact, if the cylinder is of a different geometry than the configuration of these elements, it would be adapted in the same way.

The piston crown 2d includes oil control aspects 2e to control the degree of lubrication humidity of the cylinder 1 during engine operation. These aspects comprise an oil control groove and ring as they are commonly employed in conventional internal combustion engines.

Central laminated elements 2f are also mounted on the piston shaft 2c. Each central element 2f is constructed from laminations of a magnetically permeable material, such as iron ferrite, to reduce the swirl of current losses during engine operation.

Spacer elements 2g are also mounted on the piston axis 2c. Each 2g spacer element has ideally low magnetic permeability and is preferably constructed of a lightweight material, such as aluminum alloy and has a 2h vacuum formed within it, further reduces its weight and thereby reduces the mechanical forces exerted on the engine that the 30 uses . Spacer elements 2g are included to fix the relative position of each of the central elements 2f and also act to limit the loss of gases from the "gas bypass" that flow out of each chamber 3, 4 through the gap between the piston and the wall and the cylinder wall, while keeping the overall mass of the piston assembly 2 to a minimum.

Support elements 2i are also mounted on the piston shaft 2c, located approximately 25% and 75% 5 of the piston extension 2 to reduce the risk of thermally induced distortion of the piston shaft 2 causing it to lock into cylinder 1 or, otherwise, damage the cylinder 1. Each support element 2i sets up a weight reduction vacuum 2j and has a slightly larger diameter 10 than the central elements 2f and the spacer elements 2g.

The support elements 2i also have a profiled outer surface 2k to support the weight of the piston 2, and any other parallel loads present, while keeping frictional losses and wear to a minimum. The support elements 2i are preferably constructed of a hard, wear-resistant material, such as ceramic or carbon, and the outer profiled surface 2k can be coated in a low-friction material. Alternatively, the support elements can incorporate aspects of rolling support as they are commonly used in sliding applications.

Similar to the piston crown or, perhaps, instead of, the support element 2i can also include aspects of oil control to control the degree of humidification of the lubrication of the cylinder 1 during the operation of the engine. These aspects comprise an oil control groove and ring as they are commonly employed in conventional internal combustion engines.

The total extension of the piston is preferably 30 five times its diameter and is at least sufficient to completely close the sliding gate valve, so that, at no time, the sliding gate valve allows combustion chambers 3 and 4 communicate. Figure 3 is a sectional view of piston 2, showing the axis of piston 2c passing through a central element 2f. The ends of the piston shaft 21 are mechanically deformed or otherwise attached to the crowns 5 of the piston 2d, so that the elements 2f, 2g, 2i that are mounted to the piston shaft 2c are safely retained under the action of tension maintained on piston shaft 2c. The alternating arrangement of central elements 2f and spacers 2g positions central laminations 2f at the correct inclination for efficient operation, such as, for example, part of a linear alternating reluctance generating machine comprising the movement of piston 2 and a linear generator means, for example, a plurality of coils spaced along the length of the cylinder within which the piston reciprocates. Figure 4 shows an example of a linear generator means 9 provided around the outside of cylinder "1, along at least a part of its extension, to facilitate the transfer of energy between piston 2 and the electrical outlet means 20 9e The linear generator means 9 includes several coils 9a and several stators 9c, in the form of magnetizable elements, alternating along the length of the linear generator means 9.

The linear generator means 9 can be of several different types of electrical machine, for example, a linear alternating reluctance generator. In the arrangement shown, the coils 9a are alternated by switching the device 9b, in order to induce magnetic fields within the magnetizable stators 9c and the central laminations of the piston 2e. The 30 magnetizable stators 9c can be laminated or constructed from a composite, magnetic, soft (SMC) material, for example. In each approach, the stators are constructed of magnetizable and electrically conductive elements separated by non-conductive material, which reduces heat losses from the magnetically induced eddy currents. The transverse magnetic flux created in the magnetizable stators 9c and central laminations of the piston 2f under the action of the alternating coils 9a is also indicated in Figure 4. The linear generator means 9 functions as a linear alternating reluctance device or as a flow device alternating linear. The energy is generated in the electrical outlet medium 9e according to the flow circuits, established in the 10 magnetizable stators 9c and induced in the central laminations of the piston 2f, are cut off by the movement of the piston 2. This allows a highly efficient means of electrical generation, without the use of permanent magnets, which can be demagnetized under high temperature conditions within an internal combustion engine, and which could otherwise add significant cost to the engine, due to the use of costly rare earth metals.

In addition, a control module 9d can be employed, comprising several different control means 20, as described below. The different control means are provided to achieve the desired rate of energy transfer between piston 2 and electrical outlet medium 9e, in order to release the maximum electrical outlet, while satisfying the desired movement characteristics 25 of piston 2, including rate and compression ratio, expansion ratio and proportion, and piston dwell time at the top dead center of each chamber 3, 4.

A valve control means can be used to control the intake valve 6c and the exhaust valve 7b. By controlling the closure of the exhaust valve 7b, the valve control means is able to control the start of the compression phase. Similarly, the valve control means can also be used to control exhaust gas recirculation (EGR), intake load and compression ratio.

A means of controlling the compression ratio that is suitable for the type of electrical machine can also be employed. For example, in the case of an alternating reluctance machine, the control of the compression ratio is partially achieved by varying the phase, frequency and current applied to the alternating coils 9a. This changes the rate at which the induced transverse flow is cut off by the movement of piston 2 and therefore changes the force that is applied to piston 2. Likewise, coils 9a can be used to control the kinetic energy of piston 2, both at a closing point of the exhaust valve 7b and during the subsequent deceleration of piston 2.

A spark ignition timing control means can then be employed to respond to any variability from cycle to residual cycle in the compression ratio, to ensure that the adverse impact of this residual variability on engine emissions and efficiency is minimized, as follows. In general, the expected compression ratio at the end of each compression phase is the target compression ratio plus an error that is related to system variability, such as the combustion event that occurred in the opposite combustion chamber 3, 4, and the characteristics of the control system. The spark ignition timing control means can adjust the timing of the spark ignition event in response to the measured speed and acceleration of the piston 2 approach to optimize the combustion event for the expected compression ratio at the end of each ignition phase. compression.

The target compression ratio will normally be a constant depending on the fuel 5a that is used. However, a compression ratio error can be derived from a variation of +/- 20% in the height of the combustion chamber 3a. Thus, if the target compression ratio is 12: 1, the actual compression ratio can be in the range 10: 1 to 15: 1. The anticipation or delay of the spark ignition event 5 by means of spark ignition timing control, therefore, will reduce adverse emissions and have an efficiency impact on this error.

In addition, a fuel injection control means can be employed to control the timing 10 of the fuel injection 5a, so that it is injected into a combustion chamber 3, 4 just before the sliding gate valve 6a closes, to reduce hydrocarbon emissions during depletion.

In addition, a temperature control means can be provided, including one or more temperature sensors positioned in close proximity to the coils 9a, electronic devices and other elements sensitive to high temperatures, to control the flow of cooling air in the system by means of compressor 6e in response to the detected temperature changes. The temperature control means may be in communication with the valve control means to limit the energy output of the engine, when high temperature readings are detected, sustained to prevent engine damage.

Additional sensors that can be used by the 9d control module preferably include an exhaust gas sensor (Lambda) and an airflow sensor to determine the amount of fuel 5a to be injected into a chamber, according to the amount of air added, for a certain type of fuel. Likewise, a fuel sensor can also be used to determine the type of fuel being used. Figure 5a shows a perpendicular section through one of the magnetizable stator elements 9c, showing the arrangement of coils 9a and stators 9c in relation to each other. An alternative embodiment is shown in Figure 5b, in which a single stator 9c and coil 9a are used to induce magnetic flux in two adjacent pistons 2. This configuration has a cost advantage compared to that shown in Figure 5a, due to the reduced number of coils 9a required. Figure 6 is a sectional view of cylinder 1, which is preferably constructed of a material with low magnetic permeability, such as an aluminum alloy. The inner surface 1c of the cylinder 1 has a coating 1 and a hard, wear-resistant material, such as silicon carbide and nickel, silicon nitrate bonded by reaction, chromium deposition, or other metallic, ceramic or chemical coating. On the outer surface ld, an insulating coating lf, such as zirconium oxide or other sufficiently thermal insulating ceramic, is applied. It will be apparent to the technician in the matter that the whole cylinder has a construction identical to that of this sectional view of the cylinder part, close to the end of the cylinder lg. Figure 7 shows the intake means 6 provided around the cylinder 1, the intake means 6 comprising openings 6a, which are of a corresponding size and aligned with the openings la, 1b provided in the cylinder 1, and an air intake 6b. The openings 6a in the intake means 6 are connected by a channel 6h on which a intake trigger valve 6c is seated. Channel 6h is of minimal volume, having a short extension, small cross-sectional area or a combination of both, to minimize uncontrolled expansion losses within channel 6h during the expansion phase. The intake trigger valve 6c seals channel 6h of a intake pipe 6f provided adjacent to cylinder 1 as part of air intake 6b. The intake trigger valve 6c is operated by an actuating trigger valve 6d, which can be an electrically operated solenoid medium or another electrical or mechanical medium.

When the sliding gate inlet valve 6a and the inlet trigger valve 6c are both open in relation to one of the first or second chambers 3, 4, the inlet pipe 6f is in fluid communication 10 with that chamber by middle of channel 6h. Ingestion means 6 is preferably provided with a recess 6g arranged to receive the intake trigger valve 6c when fully open, to ensure that fluid can flow freely through channel 6h.

The air intake 6b also includes a intake charge compressor 6e that can be operated electrically, mechanically or under the action of pressure waves that originate from the air intake 6b. The intake charge compressor 6e can also be operated under the action of pressure waves that originate from an exhaust medium 7 provided at each end of the cylinder 1, as described below, or by a conventional turbo exhaust charger device . The intake charge compressor 6e can be a positive displacement device, centrifugal device, axial flow device, pressure wave device, or any suitable compression device. The intake charge compressor 6e raises the pressure in the intake pipe 6f, so that when the air intake 6b is open, the pressure in the intake pipe 6f is greater than the pressure in the chamber 3, 4 connected to the intake pipe. intake 6f, thereby allowing a flow of intake charge fluid.

Fuel injection means 5 are also provided within the intake means 6, such as a solenoid injector or piezo injector 5. Although a single centrally located fuel injector 5 may be suitable, there is preferably a fuel injector 5 provided in one of the 5 intake trigger valve sides 6c and arranged close to the ends of sliding gate valves 6a. The fuel injectors 5 are preferably recessed in the intake means 6, so that the piston 2 can pass back and forth between the intake valves of the sliding door 6a and the air intake 6b without obstruction. The fuel injectors 5 are configured to inject fuel into the respective chambers 3, 4 through each of the sliding door intake valves 6a

Lubrication means 10 are also provided, preferably 15, embedded within the intake means 6 and arranged so that the piston 2 can pass forwards and backwards from the intake means 6 without obstruction, thereby the piston can be lubricated. Figure 8 shows the exhaust means 7 provided 20 at each end of the cylinder 1. The exhaust means 7 comprises a piston head 7a attached removably, by means of screwing or similar, to the end of the cylinder 1. Within each piston head 7a, an exhaust trigger valve 7b, 25 is located coaxially aligned to the axis of the cylinder 1. The exhaust trigger valve 7b is operated by an actuator exhaust trigger valve 7c, which can be a solenoid operated medium electrically or other electrical or mechanical means. Likewise, when the intake trigger valve 6c and the exhaust trigger valve 7b inside the first or second chamber 3, 4 are both closed, that chamber is effectively sealed and an operating fluid contained therein can be compressed or allowed to expand. The exhaust means 7 also includes an exhaust pipe channel 7d provided inside the piston head, into which the exhaust gases can flow, under the action of a differential pressure between the adjacent first or second chamber 5, 4 and the fluid within the exhaust pipe channel 7d when an exhaust trigger valve 7b is open. The flow of the exhaust gases can best be seen in the arrangement of the cylinders illustrated in Figure 20, which shows the direction of the flow of the exhaust gas to be substantially perpendicular to the axis of the cylinder 1.

The ignition means 8, like a spark plug, are also provided at each end of the cylinder 1, the ignition means 8 being located inside the piston head 7a and, preferably, retained so that there is no obstruction of the piston 2 during the normal engine operating cycle.

The preferably coaxial arrangement of the exhaust trigger valve 7b as the axis of the cylinder 1 allows the diameter of the exhaust trigger valve 7b to be much larger in relation to the diameter of the chambers 3, 4 than in a conventional internal combustion engine.

Each piston head 7a is constructed of a wear-resistant and well-insulated material, such as ceramic, to minimize heat rejection and avoid the need for 25 separate valve seat components. Figure 9 presents a graph of time displacement of an engine, according to the present invention, illustrating the movement of piston 2 along the course of a complete engine cycle. Although the operation of the motor is described here, with reference to the first chamber 3, a person skilled in the art will recognize that the operation and sequence of events of the second chamber 4 are exactly the same as that of the first chamber 3, but 180 degrees outside the chamber. phase - that is to say, the upper dead center for the first chamber 3 occurs at the same time as the lower dead center for the second chamber 4. Figure 9a is a table that presents several 5 different compression ratio control means that they can be used to control the compression ratio in response to changes in the signals received from several different variables that can affect the compression ratio during an engine cycle. Figure 9b is a flow chart corresponding to Figure 9a. The compression ratio control means may comprise part of the control module 9d, discussed above.

Both the table and the flowchart illustrate the main variables that can affect the compression ratio in the different stages (A to F) of an engine cycle, as shown in Figure 9. These variables include: user energy demand, the type of fuel being used, compression ratio and status outside the point of the previous engine cycle, piston position and the piston kinetic energy. The table and flowchart illustrate the different processes that take place to control the compression ratio and how the different variables affect this completion of an engine cycle and also the subsequent effect of each process, which can have an effect on more than one control processes throughout the engine cycle. It can be seen that in the last step of the sequence, once the expected compression ratio has been determined, the optimal ignition timing is achieved by the spark ignition timing control means 30 which adjusts the timing of the spark event.

Events A to F, highlighted throughout the engine cycle, correspond to events A to F illustrated in Figure 10, which presents a pressure and volume chart typical for a combustion chamber 3, 4 along the course of the same engine cycle. The events featured in Figures 9 to 10 are listed in the following discussion of Figures 11 to 19.

Now considering a complete engine cycle, at the beginning of the engine cycle, the first chamber 3 contains a compressed mixture composed primarily of pre-mixed fuel and air, with a minority proportion of residual exhaust gases conserved from the previous cycle. It is well known that the presence of a controlled amount of exhaust gases is advantageous for efficient engine operation, as this can reduce or eliminate the need for regulation of intake load as a means of modulating engine energy, which is a significant source of losses in conventional spark ignition engines. In addition, the formation of polluting nitrous oxide gases is reduced since peak combustion temperatures and pressures are lower than in an engine without exhaust gas retention. This is a consequence of the fact that the fraction of the exhaust gas does not contribute to the combustion reaction and due to the high heat capacity of carbon dioxide and water in the trapped gases. Figure 11 shows the position of the piston in relation to cylinder 1, defining the geometry of the first chamber 3 in the upper dead center (A). This also approximates the starting point of the AB combustion phase. The distance between the top of piston 2b and the end of the first chamber 3 is at least half the diameter of the first chamber 3, giving a smaller surface area to volume ratio compared to the combustion chambers 30 in conventional internal combustion engines, and reducing the heat losses of the first chamber 3 during combustion. The ignition means 8 are retained within the piston head 7a, so that, in case the piston 2 approaches the upper dead center in an uncontrolled manner, there is no possibility of contact between the ignition means 8 and the crown of the piston 2d. On the contrary, the compression will continue until the movement of the piston 2 is captured by the continuous incorporation of pressure due to the approximately adiabatic compression in the first chamber 3. With reference to Figure 10, the combustion expansion phase AB is initiated by an event of ignition (A). Figure 12 shows the position of piston 2 in 10 in relation to the linear generator medium 9 in the middle of the expansion phase (AB and BC). The first chamber 3 expands as the piston 2 moves under the action of the differential pressure between the first chamber 3 and the second chamber 4. The pressure in the second chamber 4, at this point, is approximately equivalent to the pressure in the inlet pipe 6f. The expansion of the first chamber 3 is opposed by the action of the linear generator medium 9, which can be modulated in order to achieve a desired expansion rate, to meet the performance, efficiency and emissions objectives of the engine. Figure 13 shows the position of piston 2 in the lower dead center in relation to the first chamber 3. At the end of the expansion phase (C), the movement of piston 2 is stopped under the action of the linear generator means 9 and the differential pressure between the first chamber 3 and the second chamber 4. The pressure in the second chamber 4, at that point, is approximately equal to the high pressure in the first chamber 3 in its upper neutral position (A). Preferably, the expansion ratio is at least twice the compression ratio, where the compression ratio is in the range of 10: 1 to 30 16: 1. This gives an improved thermal efficiency compared to conventional internal combustion engines, where the expansion ratio is similar to the compression ratio. Figure 14 shows the arrangement of piston 2 and intake means 6 and the initial flow of intake gas at the time of the bottom dead center during the intake equalization (DC) phase. This arrangement can also be seen in Figure 7. At that point, the sliding door intake valve 6a is opened due to the piston 2 sliding back and forth from the openings la, lb provided along the inner wall 1c of cylinder 1. A pressure in the first chamber 3 is less than the pressure in the inlet pipe 6f due to over-expansion to reduce the fluid pressure in the first chamber 3 and due to the inlet compressor 6e to increase the pressure in the inlet pipe 6e. Around that time, the intake trigger valve 6c is opened by the trigger intake valve 6d allowing the intake load to enter the first chamber 3 inside cylinder 1 whose pressure approaches equalization with the pressure in the intake pipe 6f. Shortly after the intake trigger valve 6c opens, the exhaust trigger valve 7b is also opened, allowing the exhaust gases to exit the first chamber 3 under the action of the differential pressure between the first chamber 3 and the pipe channel. exhaust fan 7d, which remains closed at ambient atmospheric pressure. Figure 15 shows the position of piston 2 during the ingestion load displacement (DE) renewal phase. The evacuation of the exhaust gas is achieved by the continuous displacement of the exhaust gas in the first chamber 3 to the exhaust pipe channel 7d with fresh intake charge introduced at the piston end of the first chamber 3. Once the desired amount of charge intake valve has been admitted to the first chamber 3, the intake trigger valve 6c is closed and the exhaust gas expulsion continues through the movement of piston 2, as shown in Figure 17, explained below. Figure 16 shows the arrangement of piston 2 and intake means 6 at the fuel injection point (E). Fuel 5a is introduced directly into the approach piston crown 2d which has the effects of rapid fuel vaporization, cooling the piston crown 2d and minimization of non-burning fuel losses and emissions from a moisture film on the inner wall 1c of the cylinder 1, which could otherwise vaporize in the second chamber 4 during the expansion phase. Figure 17 shows the position of piston 2 during lubrication (E), thus, a small amount of lubricant is periodically introduced, through the lubrication means 10, directly to the external surface of piston 2a as it passes the sliding gate valve of intake 6a. This arrangement minimizes hydrocarbon emissions associated with lubricant moistening of the cylinder's inner wall and can also reduce the measure of fuel dissolution in the oil film on the inner wall of the cylinder. The central oil ring aspects 2e are included in the piston crown 2d and / or support elements 2i to further reduce the measure of lubricant wall humidification in the first and second chambers 3, 4. Figure 18 shows a position of the piston 2 during the EF piston displacement evacuation phase. The intake trigger valve 6c is closed and the exhaust gas is expelled by the movement of piston 2. Piston 2 is now moving towards the exhaust medium 7 and reducing the volume of the first chamber 3 due to the combustion event in the second chamber 4.

As a result of the relatively larger diameter of the exhaust trigger valve, as discussed above, the area of limitation in the exhaust flow beyond the valve stem can approach 40% of the internal drilling section area of the cylinder, resulting in pressure losses low exhaust return rates during both the intake charge displacement (DE) renewal phase and the piston displacement (EF) evacuation phase. Figure 19 shows a longitudinal section of a position of piston 2 in relation to cylinder 1 in the middle of the compression phase (FA). When sufficient exhaust gas expulsion is achieved, so that the proportion of exhaust gas in the fluid in the first chamber 3 is close to the desired level, the exhaust trigger valve 7b is closed and the compression phase (FA) begins. . The compression continues at a rate of change as piston 2 accelerates and decelerates under the action of the differential pressure between the first chamber 3 and the second chamber 4. The pressure in the second chamber 4 is at that point that exists during the expansion phases (AB and BC) and by the action of the linear generator medium 9. The force of the linear generator can be modulated in order to achieve the desired compression ratio to meet the performance, efficiency and emissions objectives of the engine. The compression ratio in the first chamber 3 is substantially the same and opposite to the expansion rate in the chamber 4. Figures 20A and 20B, in particular, show how the cylinder 1 is preferably located coaxially within a cylinder support 11 , which provides structural support to cylinder 1 and can also be arranged to provide the cooling medium. The cylinder support 11 can be slightly smaller than the cylinder 1 and the piston heads 7a can be attached, by means of screw fixings or any other suitable means, to the cylinder support 11 to maintain the compression between each piston head 7a and the surface of each end of the cylinder ld. Figure 20C shows the section of the cylinder support 11 having an electric machine 9e affixed. The cylinder support 11 is preferably formed by the extrusion of a ductile material, such as aluminum alloy, and arranged to provide structural support and cooling medium 12 while allowing the electricity generation components 9a-9e to be integrated in proximity strictly and precisely defined to the movement piston 1 inside the cylinder 1.

The extrusion wall of the cylinder support 11 is ideally thick and / or strong, that is, load-bearing to allow a much thinner cylinder wall 1 that projects wear and sealing surfaces than it would otherwise be , wanted. As mentioned above, the generator of the present invention comprises a plurality of magnetic coils 9a disposed on the cylinder support 11, a plurality of stators, in the form of magnetizable elements 9c and the piston 2, which acts as the moving element in this case.

The cylinder support 11 preferably has sections of material removed along the extension of the cylinder 1 to form one or more recesses 15 which, ideally, extend through the cylinder support 11 to expose the wall of the cylinder 1 housed within it. A plurality of magnetizable elements, ideally load-bearing 9c can be positioned in close proximity to cylinder 1 by arranging it in one or more recesses 15, each magnetizable element 9c being preferably fixed directly to the wall of cylinder 1, which separates from the magnetic elements of the drive circuit 2f of the piston 2.

In the example shown, only a magnetizable element 9c is provided for a recess. However, it should be noted that two or more recesses of magnetizable elements 9c can be positioned within a single recess 15, if desired, depending on the desired performance characteristics, and that not all recesses 15 must contain the same number of magnetizable elements 9c , if there is. The inner and outer surfaces of cylinder 1 provide substrates for wear and thermal coatings, respectively. A thermal coating can be applied to the outer surface of cylinder 2 in the form of an adhesive material, for example, to provide a secure, insulating load-bearing connection between cylinder 1 and cylinder holder 11. Figure 21 shows a exemplary engine arrangement 10 comprising four free piston engines configured to operate in cycles that are synchronized to create a completely balanced engine. In this configuration, the overall extension of the 50 kw generation of the engine with a thermal efficiency of around 50% is approximately 15 1400 mm. The cylinder support 11 can be affixed, by means of fixation by screw or other suitable means, to a structural support 13 that provides the basis for the mechanical fixation of the engine for a vehicle or other device that extracts electrical energy from the electrical outlet means 9e, 20 as shown in Figure 22. A compartment 14 provides a physical compartment for the engine, piping and control systems. The interfaces are provided throughout compartment 14 for intake and exhaust flows, fuel and lubricant intake, heat rejection, electric power outlet and electric power input for initiation and control. Figure 23 shows a final view of an arrangement in which a piston head 7a supports four engines, with this, the exhaust gases leave a combustion chamber of the engine 3, 4 through the exhaust trigger valve 7b and flows substantially perpendicular to the axles of the cylinders 1.

Advantageously, with the present invention, the narrow internal perforation geometry of the first chamber 3, and the relative positions of the ingestion means 6 and the exhaust means 7, which are located at the opposite ends of the first chamber 3, allow for a process effective and highly efficient evacuation system with little mixture between the intake load and the exhaust gases. This scheme offers several advantages compared to evacuation on two conventional stroke engines or two piston free stroke engines.

Firstly, the exhaust gas expulsion can be precisely controlled by timing the closing of the exhaust valve, provision of variable internal exhaust gas recirculation as a means of controlling engine energy without the need for a regulation device and losses associated motor pumping.

Second, the limited mixture between the trapped exhaust gas and the intake charge can improve the combustion completeness, since the front flame of combustion within the fresh charge is not interrupted by cracks in non-combustible exhaust gas mixed with the fuel / air mixture.

Thirdly, the introduction of fuel 5a through the fuel injector means 5 shortly before the closing of the sliding intake valve 6a, and also the introduction of lubricant through the lubrication means 10 near that time is unlikely to result in reintegration. of fuel or lubricant in the exhaust gases and cause exhaust hydrocarbon emissions.

In addition, the geometry of chambers 3, 4 is such that, at the top dead center, the distance between the top of piston 2b and the end of chambers 3, 4 is at least half the diameter of chamber 3, 4. A The rate of change of the compression ratio with the displacement of the piston in the upper dead center is, therefore, less than a conventional free piston engine of similar diameter, but in which the depth of the chamber 3, 4 is smaller. As a result, the impact of small variations in the depth of the first chamber 3 in the upper dead center due to the combustion variations in the second chamber 4, the tolerances of the control system or other sources of variability, are considerably reduced. The stability and control of the engine's operating cycle are considerably improved by this aspect.

By detecting the movement of piston 2 at the upper dead center (A), a desired compression ratio can be achieved. A target compression ratio can be in the range of 10: 1 to 16: 1, and higher compression ratios, in general, would allow greater thermal efficiencies to be achieved. Different proportions of target compression can be adjusted for different fuels, to take advantage of the octane number characteristics of the particular fuel or mixture of fuels in use. Any combination of feedback signals from an out-of-point sensor, from the piston movement, from the exhaust gas composition and from other engine operating characteristics, can be used as the input to the 9d control module in order to achieve the desired compression ratio and ratio.

An additional benefit of this achievement compared to other internal combustion engines is that noise levels are reduced due to the over-expansion cycle and that results in a low differential pressure across the exhaust valve just before opening. As a result, the shock waves that propagate through the exhaust system and cause the exhaust noise in an internal combustion engine or conventional free piston engine to be substantially avoided.

If the present invention is incorporated into a low-cost passenger vehicle having a series hybrid drive train configuration, costs for the vehicle user as a means for generating automotive electrical power are reduced, purchased from existing engine designs internal combustion. This cost reduction is a result of several factors, including the low fuel cost per unit of electricity generated due to the high thermal efficiency. Other factors include the low cost of component manufacturing due to the relatively small number of high tolerance dimensions required and, therefore, the low cost of component assembly. Also, the maintenance cost is low due to the small number of separate components and handling parts required.

In addition, the cancellation of complex auxiliary systems and the elimination of complex power transmission routes, including, highly stressing the hydrodynamic plan support characteristic of conventional internal combustion engines and the low cost of materials for the engine, due to the counting small parts and the small number of components having functional design restrictions that require the use of high-cost materials, such as permanent magnets or specialized aluminum or steel alloys are all factors that help to keep the cost low.

Thermal efficiency is also improved compared to conventional internal combustion engine designs. In addition to the factors already discussed, the improved efficiency is also a result of good heat exchange, transfer of a proportion of the exhaust, heat losses from the engine and electrical generator in the intake load, reduced frictional losses due to the elimination of loads to the wall of the cylinder during the conversion of the cylinder pressure load to the crankshaft torque and the elimination of regulation losses due to the motor energy modulation being achieved by the variable intake load flow duration at all auxiliary intake pressure and variable internal exhaust gas recirculation, not by regulating the intake air flow, as is done in a conventional spark ignition engine.

In addition, exhaust emissions (including NOx, hydrocarbon and particulate emissions) are reduced compared to other known free-piston engine designs. This reduction in exhaust emissions is a result of several factors, including: improved control of the compression ratio in each cycle, due to the elongated electrical generator geometry, which results in a high electrical control authority throughout the movement of the during the compression stroke and, therefore, a minor piston displacement error in the upper dead center; and the compressed charge variable retained exhaust gas composition to reduce peak combustion temperatures and pressures that determine NOx formation.

Claims (9)

1. METHOD OF MANUFACTURING AN ENGINE, characterized by comprising the provision of a cylinder configured to accommodate at least one piston that is free to reciprocate within the cylinder, extrusion of a cylinder support that is arranged to retain and provide structural support for the cylinder, and fixing the cylinder within the cylinder holder, so that the cylinder wall is reinforced by the cylinder holder structure. 2. METHOD, according to claim 1, characterized in that it additionally comprises the arrangement of one or more magnetizable elements to provide support that sustains load to the cylinder. METHOD, according to claim 1 or 2, characterized in that it additionally comprises the fixation of the cylinder inside the cylinder support using an adhesive material on the outside of the cylinder, wherein the adhesive material provides thermal insulation between the cylinder and support of the cylinder. cylinder. Method according to any one of claims 1 to 3, characterized in that it further comprises the provision to the cylinder support of the cooling means for cooling the cylinder. METHOD, according to any one of the claims 1 to 4, characterized in that it additionally comprises the coating of the inner wall of the cylinder with friction reducing material between the inner wall and a piston passing along it. METHOD according to any one of claims 1 to 5, characterized in that it further comprises reducing the thickness of the cylinder wall to a thickness that is less than 5% of the internal diameter of the cylinder. METHOD according to claim 6, characterized in that it further comprises limiting the thickness of the cylinder wall to less than about 2 mm. METHOD according to any one of claims 1 to 7, characterized in that it further comprises the construction of the piston using alternating magnetizable elements and non-magnetizable spacer elements. Method according to any one of claims 1 to 8, characterized in that it further comprises the provision of one or more recesses in the cylinder support that allow a plurality of magnetizable elements to be positioned adjacent to the cylinder.

Images