Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02D—CONTROLLING COMBUSTION ENGINES
  • F02D15/00—Varying compression ratio
  • F02D15/04—Varying compression ratio by alteration of volume of compression space without changing piston stroke
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
  • F02B11/00—Engines characterised by both fuel-air mixture compression and air compression, or characterised by both positive ignition and compression ignition, e.g. in different cylinders
  • F02B11/02—Engines characterised by both fuel-air mixture compression and air compression, or characterised by both positive ignition and compression ignition, e.g. in different cylinders convertible from fuel-air mixture compression to air compression or vice versa
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
  • F02B41/00—Engines characterised by special means for improving conversion of heat or pressure energy into mechanical power
  • F02B41/02—Engines with prolonged expansion
  • F02B41/04—Engines with prolonged expansion in main cylinders
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
  • F02B1/00—Engines characterised by fuel-air mixture compression
  • F02B1/02—Engines characterised by fuel-air mixture compression with positive ignition
  • F02B1/04—Engines characterised by fuel-air mixture compression with positive ignition with fuel-air mixture admission into cylinder
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
  • Y02T—CLIMATE CHANGE MITIGATION TECHNOLOGIES RELATED TO TRANSPORTATION
  • Y02T10/00—Road transport of goods or passengers
  • Y02T10/10—Internal combustion engine [ICE] based vehicles
  • Y02T10/12—Improving ICE efficiencies

Definitions

• the present invention refers to the technical field of internal combustion spark ignition engines.
• the aim of the invention is to confer to the internal combustion engine a multifuel capability combined with maximum thermodynamic efficiency corresponding to each particular fuel used.
• the multifuel characteristic will be extremely convenient during the phase of petroleum derivates substitution by alternative fuels.
• thermodynamic efficiency of an internal combustion engine is basically an increasing function of both the compression ratio and of the expansion ratio.
• thermodynamic efficiency is a function of the compression ratio only.
• the conversion of heat into mechanical work is exclusively accomplished during the expansion of the hot burned gases which form the thermodynamic medium, and this conversion is as much complete as the expansion ratio increases.
• the increase of the compression ratio leads also to the increase of efficiency by raising the energy level of the gases before the combustion.
• the compression ratio is limited by the apparition of an abnormal combustion phenomenon known as detonation, or popularly as knock.
• detonation or popularly as knock.
• the start of detonation depends mainly on the anti-knock characterijstic of the fuel and on the value of the compression ratio.
• the expansion ratio is the same as the compression ratio, the highest possible value of the expansion ratio will depend on the limit imposed by the compression ratio.
• thermodynamic cycle which results from the distinction of a higher expansion ratio from a lower compression ratio is know as a "more-complete-exapansion" cycle whose description can be found in good text-books on combustion engines.
• Two procedures to achieve the "more-complete-expansion" cycle are well known. One of them consists of an earlier closing of the intake valve, thus reducing the effective intake stroke.
• This procedure creates a very low gas pressure at the end of the intake stroke and consequently conduces to a lower final compression pressure rather than to a lower compression ratio, accordingly to the anti-knock value of a particular fuel.
• Another way consists in the substitution of the conventional crankshaft by other mechanical device which gives longer stroke for the expansion and the exhaust, and shorter stroke for the intake and the compression.
• This mechanical device may consist of a shaft with two cams actuating on the piston movement. This cams are designed in such a way that they produce two different strokes.
• c) DISCLOSURE OF INVENTION The invention on which this call of privilege is based, pre sents a way to combine a conveniently high expansion ratio with an effective compression ratio suitable to the antiknock value of a particular fuel.
• the invention includes also the possibility of an easy and fast adjustament of the effective compression ratio according to the requirements of different fuels.
• the multifuel characteristic requires, besides the compression ratio change, a controlled adjustament of the fuel/air ratio at the carburetor. Because this procedure is well known and can be performed by needle jets, it is not considered in this invention.
• the present invention makes use of intake gas recirculation to adapt a geometric compression ratio, equal to the expan sion ratio, into a variable effective compression ratio.
• the cylinder head has a third valve actuated by a cam added to the conventional camshaft system, or by a second camshaft.
• the third valve will be called recirculation valve.
• the recirculation valve will be opened by the corresponding cam at the beginning of the compression stroke thus allowing that a part of the charge of fresh gases leaves the cylinder. While the valve remains open, there will be no compres sion of gases buth there will be a discharge of fresh gases through the recirculation valve.
• the recirculation valve is closed by the corresponding cam, and at that point the effective compression of the remaining gases begins at a value corresponding to the fuel used.
• the unburned gases which leave the cylinder through the recirculation valve are readmitted into the intake piping either of the same cylinder or of another one.
• the device to perform the above described operation is called INTAKE GAS RECIRCULATION - IGR -.
• the IGR referred to in this invention constitutes a simple and efficient way for a practical realization of the "more-complete-expansion" cycle, readily adaptable to different fuels.
• the IGR procedure to vary the effective compression ratio is completely different, from the principle and mechanics of the two procedures cited in the background art section.
• the actuating cam In order to allow a change of the endurance of the open position of the recirculation valve, with the consequent variation of the effective compression ratio, the actuating cam must have distinct profiles along the longitudinal direction of the camshaft. These profiles actuate selectively according to an external control.
• the intake gas recirculation through the recirculation valve should not be confused with a third valve generally used in stratified charge engines, when a rich combustible mixture is introduced into a prechamber where these gases are ignited by a spark plug. The resulting flames in the prechamber ignite the mixture of fresh gases in the main chamber.
• the third valve has no influence on the value of the compression ratio or of the expansion ratio, and consequently on the thermodynamic efficiency optimized for different fuels.
• the intake gas recirculation - IGR - should not be confounded, with exhaust gas recirculation - EGR - where part of the burned and expanded gases are recycled into the intake system. This procedure aims the reduction of pollution and/or improving fuel economy.
• IGR is the improvement of the homogeneity of the air/fuel mixture, which favors the quality of combustion and permits the use of leaner mixtures.
• the fuel used is hydrated alcohol
• the IGR permits a large variation in the proof value of the alcohol, consider ing that different water contents in the alcohol produce different anti-knock values, and therefore require different compression ratios.
• the mechanical system shown at figures 1 and 2 referring to the present invention consists of a cylinder head (1), with spark plug (2), two conventional intake and exhaust valves (3), a recirculation valve (4) with the corresponding actuating mechanism (5) which assures the operation of the recirculation valve (4).
• the recirculation valve (4) is actuated by the cam (7).
• the outlet of the valve (4) is connected by means of a recircu lating tube (8) to the intake tube (9) of the engine.
• the cam (7) has a proper shape to give the actuating movement to the recirculation valve (4) in order to maintain the valve (4) opened during the compression stroke at a piston movement from position (9) - bottom dead center - to another preselected position (10) from where the desired effective compression starts until position (11) - top dead center-.
• the invention is directly applicable in the existing automotive engine industry, or on SI engines for other purposes.

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• Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Combustion & Propulsion (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Output Control And Ontrol Of Special Type Engine (AREA)

Applications Claiming Priority (2)

Publications (1)

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• 1979
  • 1979-09-06 BR BR7905726A patent/BR7905726A/pt unknown
• 1980
  • 1980-09-05 GB GB8117259A patent/GB2072957B/en not_active Expired
  • 1980-09-05 WO PCT/BR1980/000011 patent/WO1981000739A1/en unknown
• 1981
  • 1981-03-23 EP EP80901713A patent/EP0035525A1/en not_active Withdrawn

Non-Patent Citations (1)

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