Abstract: A control system of a hybrid vehicle includes: an engine that generates power by burning fuel; a driving motor that assists the power from the engine by generating power using electricity supplied from a battery; an integrated starter-generator that starts the engine and charges the battery by operating selectively as a power generator; an atmospheric sensor that measures the atmospheric pressure; a temperature sensor that measures the temperature of intake air flowing into the engine; and a controller that calculates a control factor, using the atmospheric pressure measured by the atmospheric sensor and the temperature of intake air measured by the temperature sensor, and adjusts a State of Charge (SOC) charge band between an SOC where charging the battery is started and an SOC where a hybrid vehicle runs in a charge mode, in accordance with the magnitude of the control mode.

Abstract: The use of porous materials in the dead space of reciprocating engines is described. The porous material can be used to condition the cylinder gases. In addition, the porous material may include a catalyst for driving chemical reactions. The catalytic process occurs on the porous material, not on the cylinder walls. The engine parameters (number of cycles, number of strokes per cycle, compression ratio, engine speed, cylinder volume, valves timing, gas composition, pressure and temperature) are adjusted to optimize gas compression or chemical reactor performance.

Abstract: A fluid vessel, in particular a liquid vessel, in particular for an exhaust-gas purification fluid for the treatment of exhaust gas of an internal combustion engine, in particular for an aqueous urea solution, wherein the fluid vessel has a filler pipe which is connected in fluid-conducting fashion to an interior of the fluid vessel and which, at an end remote from the interior of the fluid vessel, has a filler head and is closed off by means of a removable tank cover, wherein the fluid vessel and the filler pipe are designed and arranged such that, when the fluid vessel is in an installed position, a geodetically highest point of the fluid vessel is situated geodetically lower than the filler head. One ventilation device is arranged in the tank cover and at the geodetically highest point, when the fluid vessel is in the installed position, of the fluid vessel.

Abstract: In a specific embodiment of this invention, deposits and soot formation in a direct injection engine are reduced by passivating the injectors to within 0.1 mm of the injector nozzle. The fuel used with the inventive injectors comprises fuel-soluble additives.

Abstract: A system for providing a catalyst to a first flow of gas. The first flow of gas has an operating pressure. A pipe carries the first flow of gas from a compressor of a turbocharger to a combustion chamber. The operating pressure of the first flow of gas varies in accordance with an operation of the compressor. The system includes an enclosure, a pump, and an atomizer. The enclosure receives a portion of the first flow of gas at the operating pressure. The pump is positioned in the enclosure. The pump receives from within the enclosure the portion of the first flow of gas. The pump provides the portion of the first flow of gas at a second pressure. Any gas that exits the enclosure is provided by the pump at the second pressure. The atomizer receives a solution having the catalyst and provides a vapor having the catalyst. The portion of the first flow of gas at the second pressure carries the vapor out of the system and into the first flow of gas for delivery to the combustion chamber.

Abstract: In a specific embodiment of this invention, deposits and soot formation in a direct injection engine are reduced by passivating the injectors to within 0.1 mm of the injector nozzle. The fuel used with the inventive injectors comprises fuel-soluble additives.

Abstract: A system and method for delivering catalytic molecular structure to a combustion chamber is disclosed. Catalyst base materials are reduced to a micronic fog by a device using the ultrasonic vibration of a piezoelectric disc. The liquid base materials evaporate instantly upon entering the engines air stream therefore releasing pure catalyst molecules into the combustion zone, thus reducing the time taken for catalytic combustion to the lowest denominator possible and allowing for the greatest effect achievable. This further reduces the amount of catalyst needed in the base solution compared to any other type of device or additive. The system also allows a user to control the delivery rate of the catalyst to the combustion chamber.

Abstract: An internal combustion engine having at least one piston cylinder comprising a housing enclosing twin gas injectors and having two inlet openings for separate supply of hydrogen gas and oxygen gas to a combustion chamber of the piston cylinder, two pressure-controlled and time-controlled, electrical inlet valves and associated nozzle needles coupled to the housing, wherein the combustion chamber has an outlet opening for ejection of a combustion product, and a thermolysis catalyst covering the combustion chamber. The thermolysis catalyst includes two hollow cylinders arranged at a distance from one another and concentrically and surrounding an intermediate space. The walls of the hollow cylinders defining the intermediate space have a metal coating for release of the heat of combustion acting on the inner hollow cylinder. The outer hollow cylinder includes an inlet opening for the supply of water, an outlet opening for the release of oxyhydrogen gas and a temperature sensor for control of water supply.

Abstract: A fuel ignition system for an internal combustion engine is disclosed. The fuel ignition system is adapted to allow a photocatalyst to ignite a mixture by using a light energy irradiated from a light generator. The fuel ignition system includes: a combustion chamber; the photocatalyst provided in the combustion chamber; and a light generator for flatly irradiating the light energy to the photocatalyst.

Abstract: Hydrocarbon transformations through radical reaction are carried out in presence of: a carbon nano/meso precursor, an aluminium containing support, and a lanthanide catalyst deposited on said aluminium containing support.

Abstract: Efficient fuel combustion catalyst delivery device and method are provided. A fuel combustion catalyst delivery device includes a storage vessel that contains a liquid. The liquid includes one or more catalytic materials. The storage vessel is attached to a nebulizer that can convert the liquid to an aerosol to be delivered into an air intake of a combustion zone. The aerosol can accelerate fuel combustion. The storage vessel and the nebulizer are made from materials suitable to be exposed to the liquid and the aerosol. The storage vessel and the nebulizer are also suitable to be placed in proximity to the combustion zone such as an engine compartment so that the aerosol can be delivered into the air intake of the combustion zone easily and effectively. The surfaces of the delivery device exposed to the liquid or the aerosol may be made of corrosion-resistant or inert materials if the liquid is acidic.

Abstract: An internal combustion engine having at least one piston cylinder comprising a housing enclosing twin gas injectors and having two inlet openings for separate supply of hydrogen gas and oxygen gas to a combustion chamber of the piston cylinder, two pressure-controlled and time-controlled, electrical inlet valves and associated nozzle needles coupled to the housing, wherein the combustion chamber has an outlet opening for ejection of a combustion product, and a thermolysis catalyst covering the combustion chamber. The thermolysis catalyst includes two hollow cylinders arranged at a distance from one another and concentrically and surrounding an intermediate space. The walls of the hollow cylinders defining the intermediate space have a metal coating for release of the heat of combustion acting on the inner hollow cylinder. The outer hollow cylinder includes an inlet opening for the supply of water, an outlet opening for the release of oxyhydrogen gas and a temperature sensor for control of water supply.

Abstract: A coating and coating process to improve the efficiency of hydrocarbon fueled engines, wherein the coating includes a high percentage of nickel to create a reaction which improves the combustion efficiency of the hydrocarbon fuel. The coating may also include chromium, iron, and other constituents and is applied to combustion surfaces with a sufficient bonding strength to allow the coating to function in the combustion chamber, while providing a surface having sufficient surface roughness to promote the chemical reaction underlying the combustion efficiency improvement. The nickel causes a catalytic cracking reaction to ease the combustibility of hydrocarbon molecules in the fuel.

Abstract: Catalytic system combining an aluminium or iron containing catalytic support, a rare earth containing porous deposit, carbon nanoparticles and a carbon containing structure making bonds between carbon nanoparticles.

Abstract: Efficient and effective fuel combustion catalyst delivery apparatus is disclosed. A fuel combustion catalyst delivery apparatus may include a receptacle containing a material such as a liquid. The liquid may include one or more catalytic materials. The apparatus may further include a vibration pump configured to convert the liquid to an aerosol to be delivered into an intake air of a combustion zone, a pressure equalizer configured to maintain the pressure level of the receptacle at about the same pressure level as that of the intake air of the combustion zone, and a liquid delivery device configured to deliver the liquid to the vibration pump. The apparatus may further include an electronic control module and a mounting bracket or a docking station. The electronic control module may be used to control the vibration pump.

Abstract: The present invention provides a heated catalyzed fuel injector that dispenses fuel substantially exclusively during the power stroke of an internal combustion engine, wherein ignition occurs in a fast burn zone at high fuel density such that a leading surface of the fuel is completely burned within several microseconds. In operation, the fuel injector precisely meters instantly igniting fuel at a predetermined crank angle for optimal power stroke production. Specifically, the fuel is metered into the fuel injector, such that the fuel injector heats, vaporizes, compresses and mildly oxidizes the fuel, and then dispenses the fuel as a relatively low pressure gas column into a combustion chamber of the engine.

Abstract: The present invention provides an injector-ignition fuel injector for an internal combustion engine, comprising an input fuel metering system for dispensing a next fuel charge into a pressurizing chamber, a pressurization ram system including a pressurization ram for compressing the fuel charge within the pressurizing chamber, wherein the fuel charge is heated in the pressurization chamber in the presence of a catalyst, and an injector nozzle for injecting the heated catalyzed fuel charge into a combustion chamber of the internal combustion engine.

Abstract: Catalyst is supported at least on a part of the combustion chamber wall of an internal combustion engine. A control is provided for controlling the fuel injection equipment of the engine so that pilot fuel injection is performed prior to main fuel injection under prescribed operating conditions of the engine. A control is provided for controlling so that the exhaust valve is reopened for a prescribed period at prescribed timing, or the inlet valve is reopened for a prescribed period at prescribed timing, under prescribed operating conditions of the engine. By the combination of providing catalyst on the combustion wall and controlling fuel injection and valve overlapping, the exhaust emission of internal combustion engine can be drastically improved. The catalyst supporting structure to carry catalyst on the heat insulating material coated on a wall to which combustion gas contacts can be effectively applied to every type of heat engine.

Abstract: The combustion process is carried out in presence of a primary catalyst coating which is treated when required by means of cerium/europium compound in presence of water vapor and advantageously in presence of a refractory material, such as a clay, a hydrated clay.

Abstract: An internal combustion engine and a method of operating same are provided with direct injection of gaseous fuel into a combustion chamber and an ignition assist apparatus disposed within the combustion chamber. An ignition assist apparatus disposed within the combustion chamber comprises an electric incandescent ignitor with a sleeve disposed around the ignitor and a catalytic alloy. The catalytic alloy comprises a first catalytic element with a greater affinity for oxygen than that of a second catalytic element, and the second catalytic element having a greater affinity for the fuel than that of the first catalytic element.

Abstract: An engine's cylinder having a layer coated with nano-gold and nano-titanium to the inner wall thereof. An excellent catalysis can be achieved due to the fine structure and the surface effect of the nano-gold and the nano-titanium as catalyst.

Abstract: An internal combustion engine having a cylinder and a piston movable in the cylinder, the cylinder and piston defining a combustion chamber enclosed by the cylinder and the piston, a surface of at least one of at least one component of the combustion chamber and an adjoining space that comes into contact with at least one of a fuel-air mixture to be combusted and with motor oil has, at least in certain areas, a catalytic coating for oxidizing carbonization residues, the coating consists of a ternary vanadium oxide compound and at least one other compound of at least one metal oxide, the metal oxide is at least one of the group consisting of a cerium oxide, an oxide of another rare-earth metal, an oxide of lanthanum (La), and an oxide of a transition metal.

Abstract: The invention relates to an internal combustion engine (10) with at least one combustion chamber (16) enclosed by a cylinder (12) and a piston (14) arranged to move therein. A surface of at least one component of the combustion chamber (16) and/or an adjacent chamber, which comes into contact with the air/fuel mixture for combustion or with motor oil, is provided at least partly with a catalytic coating for oxidation of coking residues.

Abstract: A fuel catalyst for improving combustion efficiency is provided that includes at least one hydride producing element, and at least one element of greater activity on the electrolytic scale than the hydride producing element and at least one element of lesser activity on the electrolytic scale than the hydride producing element. The hydride producing element preferably includes an element from at least one of a Group IV and Group V of the periodic table. The element of greater activity and the element of lesser activity preferably includes at least one of zinc, magnesium, aluminum, palladium, silver, copper and cerium. Preferred formulations of the catalyst element include: a) 20-60% wt antimony, 10-30% wt tin, 10-80% wt zinc and 1-5% wt silver; b) 40% wt antimony, 18 % wt tin, 40% wt zinc and 2% wt silver; c) 20-60% wt antimony, 10-30% wt tin, 20-80 % wt magnesium, 1-8% wt cerium and 0.1-1.0% wt palladium; d) 40% wt antimony, 25 % wt tin, 30% wt magnesium, 4.8% wt cerium and 0.

Abstract: Catalyst structure, engine, and fuel injection system are disclosed, in which a catalyst structure is positioned between a fuel injector and a combustion chamber in which most or all combustion occurs. The catalyst structure typically promotes some combustion of the fuel, reforming of fuel to generate hydrogen and other reduced species of fuel molecules, or both. The catalyst structure may instead or additionally promote evaporation of fuel droplets. Benefits include reduced emissions of pollutants.

Abstract: The combustion process is carried out in presence of a primary catalyst coating which is treated when required by means of cerium/europium compound in presence of water vapor and advantageously in presence of a refractory material, such as a clay, a hydrated clay.

Abstract: A coating and coating process to improve the efficiency of hydrocarbon fueled engines, wherein the coating includes a high percentage of nickel to create a reaction which improves the combustion efficiency of the hydrocarbon fuel. The coating may also include chromium, iron, and other constituents and is applied to combustion surfaces with a sufficient bonding strength to allow the coating to function in the combustion chamber, while providing a surface having sufficient surface roughness to promote the chemical reaction underlying the combustion efficiency improvement. The nickel causes a catalytic cracking reaction to ease the combustibility of hydrocarbon molecules in the fuel.

Abstract: A corrosion resistant piston for use in an exhaust gas recirculation diesel engine. The piston includes a crown portion having ring grooves formed around a periphery of the crown portion. The ring grooves are separated by ring lands. The piston also includes a piston rod connecting portion that extends from the crown portion. The piston is made of steel and includes an electroless coating of nickel having a maximum thickness of 8 micrometers.

Abstract: A catalytically active surface is provided on the clean, combustion-exposed parts of an internal combustion engine that is green, has low operating hours, or is of modern, low emission design. A substrate or thermal barrier coat of high surface area and preferably capable of maintaining a surface temperature of at least 450° C. is deposited in the combustion chamber. Zirconia, silica, or lube oil ash are suitable. A catalytically active moiety such as platinum or iron is dispersed in, on, or with the combustion facing surface of the substrate. Nanophase iron from ferrocene or nanophase platinum are suitable. Catalytic action is maintained by continuously providing a low level of catalytic precursor to the engine in the combustion charge.

Abstract: A coating and coating process to improve the efficiency of hydrocarbon fueled engines, wherein the coating includes a high percentage of nickel to create a reaction which improves the combustion efficiency of the hydrocarbon fuel. The coating may also include chromium, iron, and other constituents and is applied to combustion surfaces with a sufficient bonding strength to allow the coating to function in the combustion chamber, while providing a surface having sufficient surface roughness to promote the chemical reaction underlying the combustion efficiency improvement. The nickel causes a catalytic cracking reaction to ease the combustibility of hydrocarbon molecules in the fuel.

Abstract: A corrosion resistant piston for use in an exhaust gas recirculation diesel engine. The piston includes a crown portion having ring grooves formed around a periphery of the crown portion. The ring grooves are separated by ring lands. The piston also includes a piston rod connecting portion that extends from the crown portion. The piston is made of steel and includes an electroless coating of nickel having a maximum thickness of 8 micrometers.

Abstract: Catalyst structure, engine, and fuel injection system are disclosed, in which a catalyst structure is positioned between a fuel injector and a combustion chamber in which most or all combustion occurs. The catalyst structure typically promotes some combustion of the fuel, reforming of fuel to generate hydrogen and other reduced species of fuel molecules, or both. The catalyst structure may instead or additionally promote evaporation of fuel droplets. Benefits include reduced emissions of pollutants.

Abstract: Methods and apparatus for reducing the TPM level of a diesel engine exhaust stream by providing a suitable oxidation catalyst into the exhaust train. The oxidation catalyst may be incorporated into a thermal insulative coating on the inner surface of the exhaust train, particularly the exhaust manifold and exhaust pipes prior to the turbocharger. Alternatively, when the exhaust train includes a turbocharger, the catalyst can be in a separate monolithic unit between the engine and the turbocharger. The system may also include an improved diesel oxidation catalyst unit having a metal monolithic substrate. The oxidation catalyst can also be incorporated into a thermal insulative coating inside the cylinders, particularly on non-rubbing surfaces such as The invention also includes the use of a protective mullite top coat on the thermal coating. A further embodiment is the use of a stainless steel bond coat to bind the thermal coating to a metallic substrate, particularly an aluminum substrate.

Abstract: A catalyzer for a Diesel engine , where the catalyzer is located inside the combustion chamber, the pre-combustion chamber, the injector or the pre-heater. In one embodiment, the interior of the pre-combustion or combustion chamber is coated with a ceramic layer and submerged in an aluminum hydroxide and zirconium suspension. A coating of catalytic metals, such as rhodium, platinum, palladium, copper, silver aluminum, manganese and zinc, is then applied to the ceramic base inside the chamber. In another embodiment, the coating is applied by replacing the ceramic base by a bath of catalytic metals.

Abstract: Hydrocarbon emissions from direct injected spark ignition engines are reduced as a result of post-flame oxidation by a catalytic material deposited on the top of a piston disposed in the engine.

Abstract: An apparatus for controlling an internal combustion engine has an amount-of-intake-air control unit for generating a command value for the opening of a flow control valve in an intake passage of the engine, which emits exhaust gases through a catalytic converter, so as to increase an amount of intake air introduced into a combustion chamber by a predetermined quantity greater when the engine operates in an idling mode after it has started to operate than when the engine operates in a normal idling mode, and controlling the opening of the flow control valve based on the generated command value, and an ignition timing control unit for controlling the ignition timing according to a feedback control process to correct the ignition timing so as to be retarded in order to converge the rotational speed of the engine to a predetermined target rotational speed while the amount of intake air is being increased.

Abstract: A combustion catalyst device for an internal combustion engine of the type including an engine unit a cylinder head, and a cylinder head gasket, including multilayered crimp or crimpless seals arranged therebetween, and cylinders, each housing a moving piston defining a combustion chamber. The catalyst is deposited on a catalyst support disposed in the combustion chamber at a position level with the edge of the cylinder head gasket.

Abstract: A composite structure includes a self-supporting substrate and a thermal barrier coating of zirconia stabilized with scandia and yttria. A method of protecting the surface of a self-supporting substrate from degradation caused by exposure to temperatures above 1200.degree. C. includes the step of applying to the surface a coating of zirconia stabilized with scandia and yttria.

Abstract: Methods and apparatus for reducing the TPM level of a diesel engine exhaust stream by providing a suitable oxidation catalyst into the exhaust train. The oxidation catalyst may be incorporated into a thermal insulative coating on the inner surface of the exhaust train, particularly the exhaust manifold and exhaust pipes prior to the turbocharger. Alternatively, when the exhaust train includes a turbocharger, the catalyst can be in a separate monolithic unit between the engine and the turbocharger. The system may also include an improved diesel oxidation catalyst unit having a metal monolithic substrate.

Abstract: Articles for hot hydrocarbon fluid wherein the surface for contacting the fluid is a diffusion barrier material or a catalytic material coated on a metal substrate. The material is either catalytically-inactive tantalum oxide which inhibits the formation of coke in the fluid or catalytically-active zirconium oxide which promotes the formation of a loosely adherent coke in the fluid while inhibiting the formation of gum in the fluid. The coating materials, i.e., the diffusion barrier coating material and the catalytic coating material, are deposited by chemical vapor deposition (CVD), e.g., by effusive chemical vapor deposition of an organometallic compound on the surface without the use of carrier gas, without pre-oxidation of the surface and without thermal decomposition of the diffusion barrier material or the catalytic coating material.

Abstract: A combustion method for an internal combustion engine which prevents the occurrence of engine knock and improves fuel consumption and economy, by spray injecting part of the fuel used in one cycle into a combustion chamber, performing preliminary combustion of a diluted air-fuel mixture below combustible limits at a temperature lower than the self-igniting temperature of the fuel, then injecting the remaining fuel into the combustion chamber, and performing main combustion by flame propagation using spark plugs as ignition sources. Accordingly, the combustion method for an internal combustion engine of the present invention can attain stable combustion even at high air-fuel ratios and makes high compression ratios possible.

Abstract: A fuel treatment device treats fuel prior to combustion in order to improve combustion efficiency and reduce exhaust emissions in hydrocarbon fuel burning systems. The fuel treatment device includes at least one element comprising tin, antimony, lead and mercury that is brought in contact with fuel to be treated. The element comprises the following percentages by weight: 60-80% tin; 15-30% antimony; 2-7% lead; and 3-12% mercury. In a further preferred embodiment, the element comprises the following percentages by weight: 70-75% tin; 15-30% antimony; 2-7% lead; and 3-12% mercury. In a still further preferred embodiment, the element comprises an alloy including approximately 75% wt tin, 21% wt antimony and 4% wt lead, wherein 0.5 kg of mercury and 0.020 kg platinum is added to 5.0 kg of the alloy. The fuel is treated as it comes into contact with the element.

Abstract: A catalyzer arrangement for the exhaust gases of an internal combustion engine in which the catalyzer body (6, 7) is formed from a weave, knit or fabric of metal fibers, metal chips, metal wires, metal powder or a mixture of them which is pressed together in several layers (11) to form a pack in the outlet region (4) of the cylinder of the internal combustion engine in front of the exhaust gas manifold (5) and/or in the inlet region of the exhaust gas manifold (5). In addition, or as an alternative, the cylinder crown (8) in the cylinder (2) of the internal combustion engine can also be provided with a catalyzer body (9).

Abstract: An improved combustion igniter for internal combustion engines is disclosed, comprising a conventional spark plug improved through the addition of (a) an upwardly facing generally vertical wire element secured to the negative cathode of the spark plug and spaced apart from the positive electrode anode of the spark plug, (b) a catalyst material proximate the vertical wire element and either secured to the spark plug body or applied to the cylinder head; and (c) an injected steam source for facilitating catalytic breakdown of vapors in the combination chamber. Preferably the wire element comprises wire of pure platinum approximately 0.018" in diameter and 1/8" in length, and the catalyst is either (1) a nickel coating disposed on the cylinder head, (2) nickel wire with platinum segments disposed thereon secured to the park plug body, or (3) sheet nickel formed in a coil and disposed in the cylinder.

Abstract: An ignition system comprising one of a glow plug, spark plug and glow attachment having metal or ceramic surfaces which are exposed to a fuel/air mixtuer, and are at least partially covered with a coating comprising at least one complex metal oxide obtained as a result of a reaction of a basic oxide selected from a group comprising oxides of Si, Y, La and Ce and mixed oxides of the above-mentioned oxides with Al.sub.2 O.sub.3, with at least one further oxide selected from a group comprising oxides of alkali and alkali earth metals.

Abstract: Operation of in-cylinder fuel injected internal combustion engines is improved by use of exhaust valves having an effective ignition catalyt on the valve face. In operation of the engine, fuel is injected into air and ignited by contact with the valve face prior to top dead center.

Abstract: Disclosed is a method of operating a catalytic ignition internal combustion engine wherein the fuel is injected into a combustion chamber at a time near maximum compression such that at least part of the fuel impinges upon an oxidation catalyst surface comprising a portion of the wall of said combustion chamber, said catalytic surface being insulated from the surroundings external to the combustion chamber by a low thermal conductivity material, said catalytic surface preferably comprising platinum. Also disclosed are combustion chambers constructed specially for the use of this method and the methods of constructing them.

Abstract: Disclosed is a method of operating a catalytic ignition internal combustion engine wherein the fuel is injected into a combustion chamber at a time near maximum compression such that at least a part of the fuel impinges upon an oxidation catalyst surface comprising a portion of the wall of said combustion chamber, said catalytic surface being insulated from the surroundings external to the combustion chamber by a low thermal conductivity material, said catalytic surface preferably comprising platinum. Also disclosed are combustion chambers constructed specially for the use of this method and the methods of constructing them.

Abstract: Disclosed is a method of operating a catalytic ignition internal combustion engine wherein the fuel is injected into a combustion chamber at a time near maximum compression such that at least part of the fuel impinges upon an oxidation catalyst surface comprising a portion of the wall of said combustion chamber, said catalytic surface being insulated from the surroundings external to the combustion chamber by a low thermal conductivity material, said catalytic surface preferably comprising platinum. Also disclosed are combustion chambers constructed specially for the use of this method and the methods of constructing them.

Abstract: A method and apparatus for improving the performance of an internal combustion engine in which a piston (10) has a hollow head (11) within the cavity of which there is mounted an open topped frusto-conical bulbous casing (13), the opening of which is covered with a mesh (14) preferably welded to its rim (15). The casing-mesh unit is attached by means of spacers (16) preferably comprising pins (17) and (21) in such a way that a space is formed between the convex exterior walls of the casing (13) and the concave interior walls of the cavity (12) of the piston head (11).