|| List of recent Internal Combustion Engine-related patents
|Exhaust manifold pressure based misfire detection for internal combustion engines|
An engine cylinder misfire detection system is provided that detects changes in exhaust manifold pressure (emp) fluctuations, compares the emp fluctuations with diagnostic thresholds determined with other engine characteristic information obtained from engine sensor data, and determines whether a cylinder misfire has occurred. A method of monitoring and detecting emp fluctuations in combination with one or more sensed engine characteristics is disclosed to determine an engine cylinder misfire in a cycle of an internal combustion engine having at least one cylinder.
|Control apparatus of internal combustion engine|
In a turbocharged internal combustion engine, an amount of cylinder suction air is calculated with sufficiently high accuracy to suitably control the internal combustion engine in consideration of influences of an exhaust pressure on a volumetric efficiency equivalent value without requiring a huge memory capacity, in fewer adaptive man hours, and under a low operation load. A correction calculation parameter is calculated using an exhaust pressure, an exhaust pressure for pre-correction volumetric efficiency equivalent value, and an intake manifold pressure, and a post-corrected volumetric efficiency equivalent value is calculated by correcting a pre-correction volumetric efficiency equivalent value using the correction calculation parameter.
|Method for operating a motor vehicle in trailing throttle mode|
In a motor vehicle with an adjustable coupling (intermediate device) between the (crank)shaft and floor contact elements (wheels), wherein the coupling is set in over trailing throttle mode in such a way that the rotational speed of the shaft is reduced, in particular is adjusted to a predefined value, in order to reduce the internal losses of the drive, in particular an internal combustion engine.. .
|Vehicle control system|
A vehicle control system includes an internal combustion engine capable of switching an operating state and a non-operating state while a vehicle travels, an engaging device capable of switching an engaged state in which the internal combustion engine is engaged with a driving wheel so that a power can be transmitted therebetween and a release state in which the engagement is released, and a controller configured to control the internal combustion engine and the engaging device based on a vehicle speed parameter as to a traveling speed of the vehicle and a determination parameter different from the vehicle speed parameter, place the engaging device in a release state at the time stop permission conditions of the internal combustion engine as to the determination parameter have been established while the vehicle travels at deceleration.. .
|Control apparatus for continuously variable transmission|
A control apparatus for a continuously variable transmission is capable of continuously changing an output of an internal combustion engine mounted on a vehicle and allowing a transmission mode to be switchable between a continuous transmission mode in which a transmission ratio is set continuously and a stepped transmission mode in which the transmission ratio is set stepwise. A transmission mode selector is configured to change the transmission mode in such a manner that in a case where the stepped transmission mode is selected, when a engine rotation speed reaches a first predetermined rotation speed, then falls below a second predetermined rotation speed which is lower than the first predetermined rotation speed, and further falls below a third predetermined rotation speed, the transmission mode is switched from the stepped transmission mode to the continuous transmission mode..
|Hybrid vehicle control apparatus|
A hybrid vehicle control apparatus (100) is provided with: a first replacement controlling device which replaces regenerative braking torque of the rotating electrical machine by engagement torque of the clutch if probability of starting an internal combustion engine is high on demand of changing a connection state between a rotating electrical machine and a transmission mechanism in regenerative braking by the regenerative braking torque of the rotating electrical machine; and a second replacement controlling device which replaces the regenerative braking torque by friction braking torque if the start probability is low on the change demand.. .
|Exhaust gas purification apparatus for an internal combustion engine|
A reduction in the accuracy of a failure determination of a filter due to a reduction in the detection accuracy of a pm sensor is suppressed. In order to achieve this, provision is made for a filter, an nox selective reduction catalyst at the downstream side of the filter, a supply device for supplying a reducing agent to the nox selective reduction catalyst, a pm sensor for detecting an amount of particulate matter in an exhaust gas at the downstream side of the nox selective reduction catalyst, and a supply decrease part that makes an amount of supply of the reducing agent smaller in cases where at least one of the following conditions is satisfied than in cases where any of the conditions is not satisfied, wherein the conditions include: a condition in which the temperature of the nox selective reduction catalyst is equal to or less than a threshold value; a condition in which the temperature of the exhaust gas is equal to or less than a threshold value; a condition in which the flow rate of the exhaust gas is equal to or larger than a threshold value; and a condition in which the amount of adsorption of the reducing agent in the nox selective reduction catalyst is equal to or larger than a threshold value..
|Device for the sealed connection of communicating ducts in adjoining and/or connected components of an internal combustion engine|
A device for the sealed connection of communicating ducts in adjoining components or an internal combustion engine includes a connecting pipe inserted into the ducts and which has a pipe portion which projects into a first component. A sealing ring is disposed between the pipe portion and an associated duct wall of the first component.
|Ignition and knock tolerance in internal combustion engine by controlling egr composition|
A method for improving ignition of a spark ignited internal combustion engine by controlling the composition of recirculated exhaust gas. It is assumed that the engine has a spark ignition system and an exhaust gas recirculation (egr) loop such that at least one of the combustion cylinders is an egr cylinder that generates an egr stream carried by the egr loop.
|Internal combustion engine having dedicated egr cylinder(s) with intake separate from intake of main cylinders|
A method and system for using an internal combustion engine with dedicated egr cylinders to provide an adjustable egr rate to the main (non dedicated) cylinders. The dedicated egr cylinder(s) are configured to receive fresh air via a fresh air intake or to receive a portion of the mixture of fresh air and egr gas via the same mixed intake line that delivers intake to the main cylinders.
|Supercharged internal combustion engine with twin-flow turbine and method for operating an internal combustion engine of said type|
A supercharged internal combustion engine may include a twin-flow turbine with variable vane geometry. One example method to operate the device permits optimized operation of the internal combustion engine at low exhaust gas flow rates..
|Internal combustion engines|
An internal combustion engine comprising at least one cylinder) and a crankshaft disposed at one end of the cylinder. Within each cylinder there is a pair of opposed, reciprocating pistons that form a combustion chamber (28) therebetween, including an outer piston being the piston furthest from the crankshaft and an inner piston.
|Internal combustion engine having a fuel supply system for stop-and-go operation|
Embodiments for an internal combustion engine are provided. In one example, and internal combustion engine comprises at least two cylinders each including an injection nozzle and a fuel supply system for supplying the cylinders with fuel.
|Spark plug for an internal combustion engine|
The invention relates to a spark plug for an internal combustion engine, in particular a gas engine. The spark plug includes a middle electrode and at least one earth electrode group, each comprising one or more earth electrode platelets.
|Pressurized engine enclosure with air filter for an agricultural work vehicle|
An engine enclosure (100, 200) for an agricultural work vehicle has a plurality of walls (114, 210, 216, 218, 230) that surround an internal combustion engine (102, 202) and a fan (122, 236) coupled to an air inlet (120, 238) in the plurality of walls for maintaining the inside of the engine enclosure (100, 200) at a pressure slightly higher than atmospheric pressure.. .
|Internal combustion engine|
To improve a propagation speed of a flame by effectively utilizing energy of the electromagnetic wave in the combustion chamber in an internal combustion engine that promotes combustion of fuel air mixture in a combustion chamber by means of an electromagnetic wave. The internal combustion engine includes, in addition to an internal combustion engine main body and an ignition device, an electromagnetic wave emission device and a control device.
|Gasoline fuel composition for improved performance in fuel injected engines|
A method for improving performance of fuel injectors, and a method for cleaning fuel injectors for an internal combustion engine. The methods include operating the engine on a fuel composition comprising a major amount of fuel and from about 1 to about 200 ppm by weight based on a total weight of the fuel of a reaction product of (i) a hydrocarbyl substituted compound containing at least one tertiary amino group and (ii) a halogen substituted c2-c8 carboxylic acid, ester, amide, or salt thereof, wherein the reaction product as made is substantially devoid of free anion species..
|Crankdisk bearing support for the waissi internal combustion engine|
An improvement to the waissi type opposed piston internal combustion engine is proposed. The engine has at least one pair of aligned and opposed cylinders with one reciprocating double-headed piston assembly in each cylinder pair.
|Liquid-cooled internal combustion engine with liquid-cooled cylinder head and with liquid-cooled cylinder block|
One approach to provide engine cooling for an internal combustion engine includes pumping coolant from a pump output, in parallel, directly to a block and a head upper coolant jacket; flowing coolant from the block directly to a head lower coolant jacket; discharging coolant from the upper and lower jackets only to a control block; and selectively directing cooling from the control block to each of: a cabin heater; radiator bypass line; and the radiator. In this way, an increased demand for pre-warmed coolant can be met, for example in the case of low outside temperatures..
|Power take-off system for an internal combustion engine|
A power take-off system for an internal combustion engine that has a drive gear positioned within a crankcase includes a housing. The housing is coupleable to the internal combustion engine.
|Method for diagnosing a low pressure exhaust gas recirculation system of an internal combustion engine and device for carrying out the method|
A method and device for diagnosing a low pressure exhaust gas recirculation system (lpegrs) of an internal combustion engine having an intake area for supplying fresh air which includes in succession in the flow direction a first section having a low pressure in which an air mass flow sensor is situated, a compressor and a second section having a high pressure, the engine exhaust area including a second section having a low exhaust gas pressure, and the lpegrs which has an adjustable lpegr valve recirculating at least a portion of the exhaust gas in the second section of the exhaust area to the first section of the intake area. The fresh air mass flow taken in is measured by the air mass flow sensor, the total mass flow flowing through the compressor being ascertained, the lpegr mass flow being ascertained from the difference between the total mass flow and the fresh air mass flow taken in, an estimated value being calculated for the lpegr mass flow, the difference between the ascertained lpegr mass flow and the estimated value being formed, and an error signal being output for a deviation.
|Hybrid vehicle control device and hybrid vehicle|
In controlling a hybrid vehicle, an internal combustion engine and an electric motor are controlled such that, when a power request is received while traveling with an operation of the internal combustion engine stopped and a requested power required for traveling is higher than a predetermined power, the operation of the internal combustion engine is started with an intake air volume based on the requested power and the hybrid vehicle travels with the requested power. When the power request is received for the first time after ignition-on, the start control for controlling the internal combustion engine is performed such that the operation of the internal combustion engine is started with an intake air volume lower than that based on the requested power.
|Method and apparatus for reducing emissions and/or reducing friction in an internal combustion engine|
A method and apparatus for reducing at least one of hc, co, and nox emissions from an operating internal combustion engine fueled by hydrocarbon or similar fuels, such as alcohols, wherein a portion of the internal combustion chamber has aluminum and/or titanium containing surfaces coated with a titanium dioxide coating further comprising a dopant in and/or on the adherent titanium dioxide coating.. .
|Assembly and method for reducing nitrogen oxides, carbon monoxide and hydrocarbons in exhausts of internal combustion engines|
An assembly and method for reducing nitrogen oxides, carbon monoxide and hydrocarbons in exhausts of internal combustion engines, wherein the exhaust is acted upon in a first stage catalytic converter. A first portion of the first stage catalytic converter output is cooled and a second portion of the catalytic converter output is not cooled.
|Push rod removal tool|
A tool for engaging and pivoting the rocker arm of an internal combustion engine to enable removal of a push rod from the engine by disengaging the rocker arm from the push rod includes a handle, a pair of bifurcated arms extending from the handle which fit on opposite sides of the rocker arm and further including connected outer ends of the bifurcated arms defining a prong to depress the valve spring. A transverse plate connecting the bifurcated arms engages the underside of a rocker arm as the bifurcated arms are positioned on the bracket supporting the rocker arm to enable pivoting the rocker arm and permit removal of the engine push rod..
|Internal combustion engine control apparatus and internal combustion engine control method|
An internal combustion engine control apparatus, which is for a vehicle which runs on power from an electric motor, derives a required power of the electric motor, derives a power that the electric motor can output by electric power supplied from the battery, derives an optimum power in the generator based on the required power and an attainable power, determines an operation mode of the internal combustion engine based on a magnitude of the optimum generator power, derives an offset value for correcting an operation point of the internal combustion engine when operated in a constant point operation mode, derives, based on the optimum generator power, a target operation point for the internal combustion engine operated in the constant point operation mode, and controls the internal combustion engine to operate at an operation point which is obtained by correcting the target operation point by the offset value.. .
|Control device of internal combustion engine|
The invention relates to a control device of an engine, calculating a control signal (svb) to be supplied to a controlled object (60v) for controlling the controlled amount to a target controlled amount and when a history of a change of the controlled amount does not correspond to a predetermined history, supplies the control signal to the controlled object and on the other hand, when the history of the change of the controlled amount corresponds to the predetermined history, the device corrects the control signal and then, supplies the corrected control signal to the controlled object. According to the invention, a model constructed on the basis of the prisach distribution function is prepared as a model relating to the controlled object for calculating a correction coefficient (khid, khdi) for correcting the control signal such that the hysteresis of the controlled object decreases, the correction of the control signal is accomplished by correcting the control signal by the correction coefficient calculated by the model, a parameter of the model is identified on the basis of the change amount of the activation condition of the controlled object during the change of the activation condition of the controlled object and the parameter of the model is corrected on the basis of the identified parameter..
A hybrid vehicle comprises an internal combustion engine, a traction motor, a starter motor, and a battery bank, all controlled by a microprocessor in accordance with the vehicle's instantaneous torque demands so that the engine is run only under conditions of high efficiency, typically only when the load is at least equal to 30% of the engine's maximum torque output. In some embodiments, a turbocharger may be provided, activated only when the load exceeds the engine's maximum torque output for an extended period; a two-speed transmission may further be provided, to further broaden the vehicle's load range.
|Method for improving engine fuel efficiency|
A method for improving fuel efficiency, while maintaining or improving high temperature wear, deposit and varnish control, in an engine lubricated with a lubricating oil by using as the lubricating oil a formulated oil. The formulated oil has a composition including a lubricating oil base stock as a major component, and at least one alkoxylated alcohol as a minor component.
|Lubricating composition containing an ester of an aromatic carboxylic acid|
The invention provides a lubricating composition containing an oil of lubricating viscosity and an ester, thioester, amide or imide of a carboxylic acid compound where said carboxylic acid is characterized in that it is functionalized with a hydroxy-substituted aromatic moiety. The invention further relates to methods of lubricating an internal combustion engine by supplying the described lubricating composition to the internal combustion engine.
|Lubricant composition for internal combustion engine oil|
The present invention provides a lubricating oil composition for internal combustion engines which includes a boronated imide-based dispersant, or the boronated imide-based dispersant and a non-boronated imide-based dispersant, in which a boron content (b % by mass) derived from the boronated imide-based dispersant and a nitrogen content (n % by mass) derived from the boronated imide-based dispersant or derived from the boronated imide-based dispersant and the non-boronated imide-based dispersant satisfy the following formula (i): n≧b+0.05 (i); and a phosphorus content (p % by mass) and a content of a metal component (m % by mass) derived from a metallic detergent on the basis of a total amount of the composition satisfy any of the following requirements a to c: a: p<0.03 and m<0.05; b: p<0.03 and 0.05≦m≦0.12; and c: 0.03≦p≦0.06 and m<0.05. The lubricating oil composition for internal combustion engines can be considerably reduced in content of zndtp having a large phosphorus content or a metallic detergent while maintaining a good wear resistance for aluminum materials..
|Catalytic converter for confined areas|
The catalytic converter for confined areas is installed with a vehicular tunnel, parking garage, or other confined area subject to motor vehicle operation therein. The converter catalyzes internal combustion engine exhaust by-products by selective catalytic reduction.
|Fuel pump for an internal combustion engine|
A high-pressure fuel pump for an internal combustion engine is described. The high-pressure fuel pump includes an improved configuration that beneficially simplifies certain features of the high-pressure fuel pump.
|Air intake duct|
There is provided an air intake duct capable of fully achieving intake-air noise attenuation effect. The air intake duct has a duct wall section formed of resin in form of tube and configured to introduce external air into an internal combustion engine or alternate power supply system.
|Method for filtering a liquid|
An oil filter assembly is disclosed for a machine, such as an internal combustion engine, that has an oil output port and an oil input port. A mounting plate is fixed with an outer enclosure.
|Egr rate control for internal combustion engine with dual exhaust-ported cylinders|
A method of using exhaust gas recirculation (egr) in an internal combustion engine. At least two of the cylinders are “dual exhaust-ported cylinders” having two exhaust ports.
|Fuel preheater and emission reducing device for diesel and other fuel injected engines|
Free heat or scavenged heat from the coolant system or circulating oil from the crankcase of an internal combustion engine supplies heat to a fuel pre-heater causing the liquid fuel to become superheated and partially vaporized. Liquid fuel preferably diesel is converted from a fluid at ambient temperature to a superheated fuel breaking down the hydrocarbons bonds of the fuel (cracking) before being sent directly to the fuel injectors.
|Method for handling fuel vapors onboard a hybrid vehicle|
A method for handling fuel vapors onboard a hybrid vehicle including an internal combustion engine or ice and a fuel system for the ice, the method including at least partly condensing fuel vapors generated in the fuel system using an absorption refrigeration device. The absorption refrigeration device includes a regenerator that uses as a heat source, heat of combustion of part of the fuel vapors that are burnt in an adequate device..
|Hybrid drive device|
A hybrid drive having a hydraulic control device capable of hydraulically controlling a first clutch, a second clutch, and a continuously variable transmission using a hydraulic pressure generated by at least one of a mechanical oil pump and an electric oil pump. A control section is configured to execute a mechanical oil pump drive mode in which a command to start an internal combustion engine is provided to drive the mechanical oil pump via a first shaft using output rotation of the internal combustion engine during reverse travel in which reverse rotation is output from the rotary electric machine to rotate wheels in reverse via the second shaft, the second clutch, and the continuously variable transmission with the first clutch disengaged and with the second clutch engaged by providing a command to the hydraulic control device..
|Fuel pump driving structure and internal combustion engine|
The fuel pump driving structure includes a camshaft and a pump cam member. The camshaft is rotatably supported at an end by a cylinder head.
|Control device for internal combustion engine|
An internal combustion engine has an ignition promotion unit that has a function of promoting ignition of fuel sprays formed by the small quantity injections by supplying the fuel sprays with electric energy. The engine is provided with a control device which has a combustion control unit that carries out processing of causing the fuel injection valve to perform the plurality of times of small quantity injections so that fuel sprays formed by the first-time small quantity injection from among the plurality of times of small quantity injections are connected with one another by the fuel sprays formed by the subsequent small quantity injections from among the plurality of times of small quantity injections..
|Fuel injector for internal combustion engines|
A fuel injector for internal combustion engines is provided, which has a valve seat member, bordering a valve chamber, having a valve seat and spray orifices and a central blind-end bore as well as a valve member that is able to be driven to cause a lift motion having a closing head, which, together with a valve seat, forms a sealing seat lying upstream of the spray orifices. In order to prevent an underpressure developing in the blind-end bore in the closing phase of the sealing seat, and a partial return flow of the fuel connected with it, the closing head of the valve member is provided, at its end face facing towards the valve seat member, with a plunger sticking out from closing head, which has a shape adjusted to the contour of the blind-end bore, and dips into the blind-end bore when the sealing seat is closed..
|Control system for a multi-fuel internal combustion engine|
The present invention is intended to suppress generation of a misfire and an increase in the amount of emission of hc, in a multi-fuel internal combustion engine of compression ignition type using, as fuels, a liquid fuel which can be ignited by compression and a gas fuel which is lower in ignitability than the liquid fuel. In the invention, in the same operating state, in cases where the liquid fuel and the gas fuel are caused to combust with the liquid fuel being used as an ignition source, the equivalent ratio of a mixture in a cylinder is made to increase, in comparison with the case where only the liquid fuel is caused to combust, and the rate of the increase of the equivalent ratio with respect to the case where only the liquid fuel is caused to combust is made smaller, when an engine load is low in comparison with the time when the engine load is high, and when an engine rotational speed is low in comparison with the time when the engine rotational speed is high..
|Oil supply apparatus of internal combustion engine|
Disclosed is an oil supply apparatus which can be realized at a low cost, and can reliably detect the lowered level of the oil filled in the oil reservoir unit. The oil supply apparatus is provided with an oil pump which is set to have a plurality of switching discharge pressures at which the oil discharge pressures are changed for each target rotation speeds when the rotation speed of the internal combustion engine reaches the respective target rotation speed.
|Piston for an internal combustion engine and method for its production|
A piston for an internal combustion engine, having a piston base body, a piston ring element having at least an inner region of a piston crown, and a piston skirt. The piston is provided with pin bosses having pin bores and the ring element has at least an outer region of a piston crown having a circumferential top land and a circumferential ring belt provided with ring grooves.
|Balancer device of internal combustion engine|
A balancer device of an internal combustion engine, has a drive gear engaged with an input gear to which a rotation force is transmitted from a crankshaft; a balancer drive shaft to which the rotation force is transmitted from the drive gear and which has a balancer weight; a balancer drive gear rotating integrally with the balancer drive shaft; a balancer driven gear engaged with the balancer drive gear; and a balancer driven shaft rotating integrally with the balancer driven gear and having a balancer weight. At least one of the drive gear, the balancer drive gear and the balancer driven gear is provided, on both axial direction side surfaces thereof, with ring-shaped grooves whose diameters are different from each other.
|Plasma generating device and internal combustion engine|
The size of the plasma produced by a plasma-generating device that generates plasma using electromagnetic (em) radiation is enlarged. The plasma-generating device has an em-wave-generating device that generates em radiation, a radiation antenna that emits the em radiation supplied from the em-wave-generating device to a target space, and a receiving antenna located near the radiation antenna.
|Preassembly of a camshaft phaser|
A camshaft phasing system (10) for an internal combustion engine (6) includes a camshaft (16) and a camshaft phaser (15) that is axially slid onto the camshaft (16) and that has stator (34) and a rotor (36) driven by the stator (34), whereby the rotor (36) is mounted rotatably relative to the stator (34). A bushing (26) that is secured on the camshaft (16) is provided, whereby the camshaft phaser (15) is tightened on the camshaft (16) against the bushing (26).
|Method for controlling a motor-vehicle provided with a propulsion system of the "mild-hybrid" type|
In a vehicle provided with a power propulsion system of the mild-hybrid type, a bas unit —including an electric machine connected through a belt transmission to the shaft of an internal combustion engine—is exploited as the only propulsion engine of the vehicle in given operating conditions. The internal combustion engine is provided with a system for variable actuation of the intake valves which is controlled to reduce the pumping losses of the internal combustion engine in the phase in which such engine is in cut-off condition and it is driven by the aforementioned bas unit.
|Supercharger control device for internal combustion engine|
A turbocharging system of an internal combustion engine includes compressor of a turbocharger disposed on an intake passage of an internal combustion engine and a turbine disposed on an exhaust passage of the internal combustion engine. A bypass passage connects an upstream side and a downstream side of the turbine in the exhaust passage together.
|Drive train of a vehicle|
A drive train (1) has an internal combustion engine (2), a traction drive (3), and working hydraulics (4) having at least one hydraulic pump (7). A connecting line (26) leads to a hydraulic accumulator (25) and is connected to a delivery line (10) of the hydraulic pump (7) that leads to the working hydraulics (4).
|Exhaust gas purification apparatus for an internal combustion engine|
In cases where at the upstream side of an nox selective reduction catalyst there is provided another catalyst, sulfur poisoning of both the catalysts is recovered in an appropriate manner. To this end, provision is made for an nh3 generation catalyst arranged in an exhaust passage of an internal combustion engine for generating nh3, the nox selective reduction catalyst arranged in the exhaust passage at a location downstream of the nh3 generation catalyst for reducing nox in a selective manner, an upstream side recovery unit to recover sulfur poisoning of the nh3 generation catalyst, and a downstream side recovery unit to recover sulfur poisoning of the nox selective reduction catalyst after the sulfur poisoning of the nh3 generation catalyst has been recovered by the upstream side recovery unit..
|Air-fuel ratio control apparatus|
When an internal combustion engine (1) is determined to be in a low-temperature start state (an affirmative determination is made in s120), an air-fuel ratio control apparatus (10) controls the temperature of a downstream detection element (17) of a downstream gas sensor (15) to a downstream target temperature by driving a downstream heater (16) of the downstream gas sensor (15) (s170), and feedback-controls the air-fuel ratio of exhaust gas based on the output of the downstream gas sensor (15) (s190). When the engine (1) is determined not to be in the low-temperature start state (a negative determination is made in s120), the air-fuel ratio control apparatus (10) drives an upstream heater (25) of an upstream gas sensor (22) and feedback-controls the air-fuel ratio of exhaust gas based on the output of the upstream gas sensor (22) (s270)..
|Process for producing a piston for an internal combustion engine and piston for an internal combustion engine|
In a process for producing a piston for an internal combustion engine, a groove is worked into a cast piston blank proceeding from a combustion chamber cavity (20) in a largely radial direction and then closed to form a cooling duct. A cast piston for an internal combustion engine has a closure which is fitted after the casting and the machining between the cooling duct and a combustion chamber cavity (20)..