Showing papers on "Compression ratio published in 1985"

Radiological image compression: full-frame bit-allocation technique.

Abstract: A full-frame bit-allocation technique has been developed for radiological image compression based on encoding the cosine transform of the image. Six different types of diagnostic images were used to examine this technique, and the results have been encouraging. Reconstructed images from compressed-image data with compression ratios of 4:1, 8:1, 12:1, and 16:1 did not have excessive visual degradation. It is concluded that this technique is suitable for diagnostic image compression.

Effects of intake-Valve Closing Timing on Spark-Ignition Engine Combustion

Abstract: When pumping loss is reduced by controlling intake-valve closing timing, an improvement in fuel economy equivalent to the reduction in pumping loss is not obtained. The major contributing factor to this phenomenon is the deterioration of the combustion, namely, increase in combustion duration and in combustion fluctuation. Therefore, an analysis is conducted on how the various factors which influence the combustion, such as the gas temperature, pressure and residual gas fraction in the cylinder during the compression stroke, change when the intake-valve closing timing is modified. As a result of experiments and simulation based on computations, it is found that the principal cause of the combustion deterioration is the drop in cylinder gas temperature and pressure which is traced to a decrease in the effective compression ratio.

System and device for exhaust gas recirculation in combustion machine

Abstract: In a spark-ignited gas engine with relatively high compression ratio of approximately e=12, operation takes place with relatively poor mixtures with air/fuel ratios of about λ=1.6 or over in order to reduce NOx production. At loads about approximately 70% of the (normally aspirated) nominal power, the oxygen-ratio must be reduced in order to aspirate sufficient fuel for the power demand. NOx-production would steeply rise, but according to the invention exhaust gas (EGR) is recirculated at least up to nominal load, in order to maintain complete combustion at λ=1.0 and meanwhile keep NO.-production low. A X-sensor in the exhaust gases may be used for that purpose. A new venturi-based mixing device (4) for the air-fuel-EGR is disclosed, placed upstream of the main throttle valve (2). The system is also applicable to diesel-gas, and straight diesel engines, with or without pressure charging. Due to the high compression ratio, thermal efficiency remains high.

Method of determining engine cylinder compression pressure and power output

Abstract: A method of diagnosing the peak compression pressure and power output of individual cylinders of an internal combustion engine based on stored normalized energy coefficients derived from a normalized pressure curve and the measured instantaneous engine speed.

Heat Loss to Combustion Chamber Wall of 4-Stroke Gasoline Engine : 1st Report, Heat Loss to Piston and Cylinder

Abstract: In an attempt to find out the thermal load conditions of the combustion chamber wall, by the use of precise thin film thermocouples which the authors have developed recently, surface temperature variation and instantaneous heat flux of the piston and the cylinder of a 4-stroke gasoline engine, for each stroke, are obtained. As a result, thermal load conditions of parts of the piston and the cylinder are made clear, and along with this, the ratio of heat loss is determined. Thermal load aspects under abnormal combustion conditions i.e. knocking are also crarified.

Structure of combustion chamber in diesel engine

Abstract: In a combustion chamber structure in a direct injection type diesel engine, in order to prevent flames from flowing out to a quench zone Q from a combustion chamber (32) which opens to a top part (30a) of a piston (30) to thereby prevent cooling of the flames and also in order to prevent a fuel spray from being concentrated on a lower portion of the combustion chamber (32), the fuel spray should be reflected in the combustion chamber (32) effectively according to displacement of the piston (30) to allow it to be mixed with air sufficiently in the combustion chamber (32) or in a cylinder (28), and to this end there are provided a guide wall (34) which becomes larger in inside diameter downwardly from an opening edge portion (33) of the combustion chamber (32), as well as fuel reflection walls (36, 38) which project below the guide wall (34) toward a central axis (lo) of the combustion chamber (32) and divide the combustion chamber vertically into a first combustion chamber (44) and a second combustion chamber (48).

Method and apparatus for detecting combustion variations in internal combustion engine

Abstract: In an internal combustion engine, a plurality of engine rotational speeds are detected at predetermined timings for every firing stroke in one cylinder of the engine, and an engine speed variation is calculated as a variation between the square of one of the engine rotational speed and the square of another of the engine rotational speed. A process is performed upon the sequence of the engine speed variations, thus determining an engine combustion state by the processed result.

Apparatus for controlling air/fuel ratio for internal combustion engine

Abstract: In an internal combustion engine equipped with exhaust gas recirculation system, air/fuel ratio control is effected using various engine parameters including atmospheric pressure. To this end, basic fuel injection duration is first computed, and this basic fuel injection duration is corrected using a correction factor so that a desired air/fuel ratio is obtained irrespective of the change in atmospheric pressure. When EGR is performed a first correction factor is derived or calculated using engine speed data, intake pressure data and atmospheric pressure data. When EGR is not performed, a second correction factor is derived or calculated using atmospheric pressure data. When obtaining the first correction factor, interpolation is used to obtain the value thereof suitable for detected engine speed, intake pressure and atmospheric pressure.

Performance and Knock Limits of Ethanol-Gasoline Blends in Spark-Ignited Engines

Abstract: Ethanol-gasoline blends have been investigated as a spark-ignition engine fuel. The work was carried out on a Ricardo E6 variable compression engine in which all the significant operating parameters can be varied and accurately measured including onset of knock. Various blends were used (10 to 70% ethanol by volume) and the effects of mixture strength, ignition timing and speed on the highest useful compression ratio were accurately defined. Borderline road test data were evaluated using information on reference fuels and the required performance of the automatic spark advance mechanism was deduced. The results revealed that higher concentration of ethanol in the blend greatly enhances knock resistance. A blend of 50% gasoline and 50% ethanol produced the highest output in both the rich and lean mixture regions. The performance of the automatic spark advance mechanism was found to vary considerably with various blends and mixture strengths. The sensitivity of optimum power attainment to ignition timing and mixture strength was illustrated. Also the saving in mechanical octanes was put forward.

Engine operating parameter control apparatus

Abstract: A control apparatus for an internal combustion engine in which the condition of the operating parameters of the engine is changed over according to the detected result of the occurrence of knocks only when the engine lies in a predetermined operating region. The operating parameters include an ignition timing, a supercharging pressure, a compression ratio, and an air/fuel ratio. The knocks of the engine are integrated and compared with a threshold level to determine which of premium or regular gasoline is being used. In this determination, if the operating region lies in said predetermined operating region, the condition of the operating parameters is changed over. The predetermined operating region is defined by a load information and a speed information of the engine.

VR/LE Engine with a Variable R/L during a Single Cycle

Abstract: A new concept of an engine, called a Variable R/L Engine (VR/LE) is presented. The main feature of the engine is the continuous change of the crank-radius to connecting-rod-length ratio (R/L) during the single engine cycle. The variations of the phase angle result in changes of all the engine stroke lengths and also-they are causing the changes of the thermodynamic cycle of the engine. Therefore the phase angle variations make it possible to regulate continuously the compression ratio and the displacement volume of the engine within the range which depends on the engine mechanism geometry. The presented concept can be applied to all the types of the IC piston engines, independently of their size and operation principle.

Engine combustion chamber pressure sensing

Abstract: An engine (10) mounted combustion chamber pressure sensor (40) is arranged with a body (42) mounted in an external wall (34), such as of the cylinder head (16), and a probe (47) engaging a combustion chamber (20) defining wall (18) to provide direct indication of combustion pressure caused movements of the chamber defining wall with respect to the external wall, thus providing direct combustion pressure signals usable for indicating or control purposes.

A procedure for calculating fuel gas blend knock rating for large bore gas engines and predicting engine operation

Abstract: This paper describes the procedure developed by Cooper-Bessemer for large bore gas engines to calculate the knock rating of gas fuel blends and to predict with accuracy the required engine build to use that fuel with optimum detonation margin. Engine prototype test work has included fuel sensitivity tests mapped as a function of compression ratio, fuel air ratio, ignition advance, combustion air temperature, and engine rating. Success in predicting production engine operation for a given application involving a particular fuel blend has been gratifying. The basic reference method blend selected was normal Butane in Methane. Details are included in the paper to illustrate the problems in making sensitivity correlations between small bore fuels research engines and large bore production engines.

Compression-ignition internal-combustion engine

Abstract: PURPOSE:To improve ignition performance, by providing an electric heater and a heated member of high heat capacity, which is located in contact with the electric heater, and by placing the heater and the heated member at a hot spot provided in a prescribed position in a combustion chamber, to enhance a rapid heating property. CONSTITUTION:Fuel is jetted out from an injection valve 1 by an injection pump 4 so that the fuel collides against a hot spot 2 provided at the tip of the injection valve 1, and is evaporated by heat and then flows into a combustion chamber 3. The fuel is passed through the internal opening 9 of a casing at the hot spot 2 so that the fuel collides against a heater 8 and a heated member 7 of high heat capacity such as stainless steel. The air around the hot spot 2 is heated not only by a temperature rise based on a adiabatic compression, but also by the heating parts 7, 8. As a result, the compression ratio of an engine can be made lower than a conventional Diesel engine dependent on only adiabatic compression, to attain the purpose.

Method of running an internal combustion engine with alternative fuels

Abstract: A method of operating an internal combustion engine with alternative preheated fuels, or mixtures thereof, at the same compression ratio and supplied with an additional medium for the operation comprises detecting the flow of air drawn into the engine through the air intake, proportioning and distributing the fuel to each cylinder in response to at least detected flow, heating the fuel fed to each cylinder to a temperature between its flame temperature and above its evaporation temperature, but below its auto ignition temperature, and injecting the heated fuel and the additional medium in a controlled amount into each cylinder through separate feed means at different angles with respect to the wall of the respective cylinder.

Selective speed limiting apparatus for internal combustion engine

Abstract: This disclosure relates to apparatus for selectively limiting the speed of an internal combustion engine by momentarily removing the ignition voltage to the spark plug of said engine at one or two preselected speeds below the maximum speed capability of the engine. Said speed limits are activated in response to electrical input signals generated by switches controlled by the operating condition of a vehicle driven by said engine. Such electrical signals could be determined by whether the vehicle transmission is in reverse and/or switches selectively operated by the operator. This emitter therefore controls the engine and thus vehicle speeds to increase the safety of the vehicle under selective operating conditions.

Deceleration based compression test

Abstract: Compression is measured in an internal combustion engine by sensing the deceleration in sub-cyclic engine speed resulting from each cylinder's compression stroke while the engine is decelerating without fuel to the cylinders and without engine load.

A procedure for calculating fuel gas blend knock rating for large-bore gas engines and predicting engine operation

Abstract: This paper describes the procedure developed by Cooper-Bessemer for large-bore gas engines to calculate the knock rating of gas fuel blends and to predict with accuracy the required engine build to use that fuel with optimum detonation margin. Engine prototype test work has included fuel sensitivity tests mapped as a function of compression ratio, fuel air ratio, ignition advance, combustion air temperature, and engine rating. Success in predicting production engine operation for a given application involving a particular fuel blend has been gratifying. The basic reference method blend selected was normal butane in methane. Details are included in the paper to illustrate the problems in making sensitivity correlations between small-bore fuel research engines and large-bore production engines.

Knocking control method and apparatus for internal combustion engine

Abstract: A method and apparatus for controlling knocking in an internal combustion engine comprising the steps of detecting the knocking which occurs in the internal combustion engine having a plurality of cylinders (CYL 1 to CYL 4), correcting the ignition timing of a cylinder (CYL 1) in which the knocking occurred, by a predetermined value based on the intensity of the knocking, and also correcting the ignition timing of the other cylinders by the predetermined value multiplied by certain coefficients.

Mechanical supercharged engine with variable compression ratio device

Abstract: PURPOSE: To prevent acceleration response from becoming worse by making compression ratio for a supercharger set at On lower than that set at OFF, and if knocking tends to occur at time of shifting from OFF to ON, setting the supercharger at ON after the compression ratio has been reduced. CONSTITUTION: The above mentioned engine is provided with a mechanical supercharger 3 continuously rotated through an engine 1 and a belt 5 in its suction path 2, and a bypass path 6 provided with a bypass valve 7 is formed around the supercharger 3, and in addition, a variable compression ratio device 10 is mounted facing on a combustion chamber 9. In case of controlling the above engine by a control computer 13, the engine is first judged of its operating under which of heavy, half and light loads, and then the supercharger 3 is set at ON in the case of the heavy load. In this case, if knocking caused by the temperature of suction or water tends to occur, the supercharger 3 is set at ON after the engine 1 has been given a low compression ratio by the variable compression ratio device 10. On the other hand, in the case of the half or light load, the supercharger 3 is set at OFF, and the engine 1 is controlled to increase its compression ratio. COPYRIGHT: (C)1987,JPO&Japio

Air fuel ratio control system for an internal combustion engine with improved operations for maintaining the engine output power

Abstract: An air/fuel ratio control system for an internal combustion engine provides a mixture leaner than a predetermined reference value when a detected engine load is in a light load range. In order to produce a required engine power during a transitional period, the system detects the speed of variation of an operating parameter used for the calculation of air/fuel ratio and controls the air/fuel ratio toward the reference level even though the magnitude of the detected engine load is in the light load range. Preferably, an EGR rate is also made smaller upon occurrence of a rapid change of the operating parameter so as to prevent the power down of the engine during the transitional period.

Intake valve mechanism in internal-combustion engine

Abstract: PURPOSE:To obtain an engine having a high compression ratio and a low S/V ratio, of such a type that three intake valves are provided for each engine cylinder, by arranging the three intake valve at specific angles so that the lower ends of the valves are maded to be approached together and as well the depth of the combustion chamber in each engine cylinder is made shallow. CONSTITUTION:The axes of three intake valves 8 provided in each engine cylinder are parallel with each other in a plane view which is observed in the direction of the axis of the engine cylinder, but come and crossing together in a side view which is observed in the direction orthogonal to a plane parallel with the axis of the engine cylinder including one of the valve axis. Further, the axis of the valve which is positioned at the middle has a small inclined angle with respect to the cylinder axis and as well a small distance from the crossing point of the valve axes to its lower end in comparison with those of the valves which are arranged at both ends. Thereby, the distance (d) among the lower ends of contact surfaces of their valve seats may be made small so that it is possible to reduce the volume of a combustion chamber 5 and to increase the compression ratio of the engine while to decrease the S/V ratio thereof.

Engine operation control means for suppressing rough engine operations

Abstract: An engine operation control system comprising a vibration detector for detecting engine vibrations and producing an engine vibration signal, an engine speed detector for detecting engine speed and producing an engine speed signal, an engine combustion control device for controlling at least one factor which governs engine combustion, an engine roughness control device adapted for receiving the engine vibration signal to distinguish engine roughness and effect control for a time period on the engine combustion control device so that the engine roughness is suppressed, a control time changing device adapted for receiving the engine speed signal and determining the time period wherein the engine combustion control device is controlled in accordance with the engine speed so that the time period is decreased as the engine speed increases.

Method and apparatus for controlling idling speed of internal combustion engine

Abstract: A method for controlling the rotational speed of an internal combustion engine in the idling state, including the steps of detecting an intake air flow rate in the engine and an air-fuel ratio of the engine and supplying the results of the decisions to a control circuit. The method includes the steps of generating output signals from the control circuit for generating the air flow rate and fuel injection amount, regulating the air flow rate while the engine is in an idling state, and regulating the fuel injection amount from a fuel injector in the engine. The method further includes the step of regulating the air flow rate while the engine is in an idling state and regulating the fuel injection amount from a fuel injector. The generation of the output signals from the control circuit is carried out by the steps of calculating an instruction output of the fuel injection amount, obtaining an air-fuel ratio closed-loop correction value, carrying out learning control for an air-fuel ratio learning correction value, deciding whether or not the engine is running under low atmospheric pressure on the basis of a comparison between the air fuel ratio learning correction value and a predetermined value, and changing the intake air flow rate for the idling state from the decision.

Engine cold starting

Abstract: A method and apparatus for starting a cold internal combustion engine under optimum conditions. Engine r.p.m. is maintained to a desired value until either the car is started, driven, or the temperature of the engine reaches a predetermined value, whichever first occurs. During this time, the ratio between the air and fuel fed to the engine is kept at the optimum values corresponding to the prevailing engine conditions during this time.

Supercharged engine charge control

Abstract: A supercharged internal combustion engine is provided with charge pressure control means, such as a turbocharger wastegate valve, to control engine charging pressure and a control system for actuating the charge pressure control means to vary charge pressure as a function of the deviation of the location of peak pressure in the engine cylinder relative to a desired value in order to control engine combustion rate and thereby the peak pressure location.

Air-fuel ratio controlling method and apparatus for an internal combustion engine

Abstract: A method and apparatus for controlling an air-fuel ratio for an engine, in which a closed-loop control and an open-loop control are performed selectively in accordance with the operating condition of the engine. The closed-loop control determines an air-fuel ratio of the mixture to be supplied to a combustion chamber on the basis of the oxygen concentration within the exhaust gas. The open-loop control determines an air-fuel ratio of the mixture by modifying the air-fuel ratio determined in the closed-loop control in a manner that the former one is lean by a predetermined ratio than the latter one.