Abstract: A method for improving fuel heating is presented. The method can reduce system complexity and cost when fuel is heated within a fuel injector. In one embodiment, the method independently heats and injects fuel by changing the direction of current flow through a fuel circuit.

Abstract: The present invention reduces exhaust emissions at startup, provides improved fuel pressure control performance in a low-load region, and detects high-pressure fuel system abnormalities. Disclosed is a high-pressure fuel system control device which includes a high-pressure pump for pressurizing fuel and discharging the pressurized fuel to a fuel rail, an injector for injecting the fuel stored in the fuel rail, and a fuel pressure sensor for measuring the pressure of the fuel stored in the fuel rail, and controls the high-pressure pump and the injector in accordance with an output generated from the fuel pressure sensor.

Abstract: A control valve assembly includes a one-piece valve movable between a first position at which the valve closes a seat defined by a housing and positioned fluidly between a fluid inlet and a first fluid outlet, and a second position at which the valve is out of contact with the seat. The valve includes an outer diameter having an annular seating shoulder located thereon which is configured to contact a frustoconical surface of the seat when the valve is at the first position, and the annular seating shoulder is further configured to deform in response to contacting the frustonical surface without changing a seating diameter associated therewith. Closing the seat with the annular seating shoulder reduces performance variability of the valve over time.

Abstract: A common rail injection system for internal combustion diesel engines is provided which is designed to correct a limit of width of an ineffective injection command pulse signal which is to be applied to each fuel injector, but causes the injector to produce no spray of fuel in order to minimize a variation in quantity of fuel injected to the engine between the injectors arising from the individual variability or aging of the injectors. The system works to changes the width of a pilot injection command pulse signal to search a value thereof when an engine operation variation such as a change in speed of the engine exceeds or decreases below a threshold at which the injector may be viewed as having sprayed the fuel actually or stopped spraying the fuel actually and determines the limit of width of the ineffective injection command pulse signal using the searched value.

Abstract: An injector with a double-switching control valve in which a valve body is guided in the housing of the control valve in a way that reduces the wear on a valve cone of the valve body and on a first valve seat in the housing of the control valve.

Abstract: A method and system controls motion of an armature 112 of a fuel injector 100. The armature moves between an open coil 118 and a close coil 116 of the injector. Acceleration current of a certain polarity is applied to the open coil 118 with the armature disposed at the close coil 116. De-latching current of a polarity opposite of the certain polarity is applied to the close coil 116 to release magnetic latch on the armature thereby accelerating movement of the armature towards the open coil 118. Deceleration current is applied the close coil 116 thereby decelerating the armature prior to reaching the open coil. Latching current of the certain polarity is applied to the open coil 118 prior to or just after impact of the armature 112 with the open coil 118 to magnetically latch the armature to the open coil 118 thereby reducing bounce of the armature at impact.

Abstract: In an injector for an accumulator injection system comprising an injector having an injector housing with an injection nozzle and an actuator for operating the injection nozzle arranged in a fuel-filled pressure space of the injector housing wherein the actuator includes a piezoelectric element disposed between an actuator head and an actuator the base with a fuel-tight casing at least partially surrounding the actuator head and the actuator base, the casing is engaged in a sealing fashion by a first annular element with the actuator base and by a second annular element with the actuator head.

Abstract: Cold start structure (10) for a fuel injection system includes a fuel rail (12) constructed and arranged to receive a source of fuel. A plurality of fuel injectors (14) is provided with each fuel injector being mounted to the fuel rail to receive fuel. Each fuel injector includes an injector body (24) having an inlet (22) and an outlet (25) and valve structure (26) in the injector body movable between open and closed positions to control flow of fuel from the outlet. Heating structure (16) is associated with each fuel injector and includes a main body (18) mounted to a portion of the fuel rail and a heating element (20) mounted with respect to the main body and extending through the fuel rail, into the inlet of the associated fuel injector, and extending into the injector body of the associated fuel injector.

Abstract: A common rail fuel injection system includes a piezo intensifier fuel injector that includes a plurality of components. Among these are a needle valve member, an intensifier piston, a first piezo stack electrical actuator and a second piezo stack electrical actuator. These components have a first configuration at which the needle valve member blocks a nozzle outlet of the fuel injector, and a shoulder of the intensifier piston is exposed to fluid pressure in a common rail. The components have a second configuration at which the nozzle outlet is fluidly connected to the common rail for a low pressure injection event. The components have a third configuration at which the nozzle outlet is fluidly blocked from the common rail, but movement of the intensifier displaces fluid through the nozzle outlet for a high pressure injection event.

Abstract: An apparatus is provided for suppressing spark damage to components of a solenoid operated valve assembly. The assembly may include a solenoid having a solenoid coil and an armature movable under the influence of the solenoid coil. A valve member may be operably connected to the armature and configured to selectively contact a valve seat. An element may be associated with the solenoid operated valve assembly and configured to suppress spark discharge between two or more of the components of the valve assembly.

Abstract: A fuel injector and servovalve for an internal combustion engine.

Abstract: A metering servovalve for a fuel injector of an internal combustion engine has an electro-actuator and a fixed valve body, which defines a control chamber communicating with an inlet and with an outlet channel. The outlet channel has at least one calibrated restriction and exits through the lateral surface of an axial stem, on which a sleeve slides, in a substantially fluid-tight manner, to open/close the outlet channel and so vary the pressure in the control chamber. The outlet channel is closed by an end portion of the sleeve that is elastically deformable in a radially outward direction, under the thrust of the fuel pressure, to increase the diameter at which the seal against the valve body is formed, with respect to a non-deformed state, and to generate a radial unbalancing force on the sleeve upon opening when the outlet channel is closed.

Abstract: An Engine Control Module includes an electronic controller for controlling the position of an EGR valve, the timing of opening and closing of the engine combustion valves, and the timing of the individual cylinder fuel injectors of an engine. Each engine cylinder includes a pressure sensor. Peak cylinder pressure is sent to the ECM during each firing cycle. The ECM is programmed with required maximum percentages of EGR and optimal combustion valve timing for each engine operating condition, and sets the EGR valve and/or the camshaft phaser accordingly to adjust combustion in all the engine cylinders. The ECM also compares the measured peak pressure for each cylinder and adjusts the timing of fuel injection for the next firing cycle to trim the measured peak pressure in each cylinder to a predetermined level at or below the maximum allowable peak firing pressure for the engine.

Abstract: A fuel injector for heating fuel to be injected into an internal combustion engine. A cylindrical barrel extends between a solenoid and an injection tip for passage of fuel. The outer surface of the barrel supports a suitable circuit pattern formed of an electrically resistive material for generating heat which is passed through the wall of the barrel to warm the fuel which may be stationary or flowing. The electrically resistive material has a positive thermal coefficient, permitting voltage to be applied continuously across the heater causing a current to flow through the heater, the current being inversely proportional to the temperature of the heater. Thus, the heater is self-regulating, the current automatically increasing under cold conditions and diminishing as the fuel injector warms up after starting of the engine. Desirably, the heater is outside both the engine firing chamber and the flow path of the fuel.

Abstract: A piezoceramic multilayer actuator has at least one outer electrode which can expand and provides at least two current paths between a supply potential connecting area of the outer electrode and a respective inner electrode, with which the outer electrode makes contact, of a piezo-stack of the multilayer actuator.

Abstract: A method for modified pulsed control of an electromechanical actuator in accordance with the invention comprising the steps of a) setting a common time length for all of the pulses in a pulse train, and b) varying (modulating) the number of such pulses per unit time (repetition rate) by varying the length of time between pulses in the train. Such control is defined herein as pulse-density modulation, or PDM. Especially in applications having a relatively low percent duty cycle if controlled by the prior art Pulse Width Modulation (PWM), PDM control results in more accurate control of an actuator, with higher resolution. The method is especially useful in controlling flow of a fluid, through a valve, such as a fuel injector, and especially at relatively low flow rates at high supply pressures P1 in the fluid supply.

Abstract: Disclosed is a method of operating an internal combustion engine simultaneously with ammonia and another fuel. The other fuel may be hydrogen, ethanol, propane, natural gas, liquefied petroleum gas, or the like. In a preferred embodiment, the other fuel is hydrogen and the engine has zero carbon emissions. A control system is programmable to adjust the proportion of ammonia and the other, catalyst fuel as selected by the operator.

Abstract: A method of control fueling of a cylinder in an internal combustion engine, the cylinder having at least two intake valves, the method comprising of operating in a first mode with one active intake valve and one inactive intake valve during a cycle of the cylinder operating in a second mode with two active intake valves during a cycle of the cylinder and adjusting a fuel injection from an injector configured to deliver fuel through at least the two intake valves, where the fuel injection adjustment is responsive to a transition in modes and based on whether the transition is from the first mode to the second mode, or from the second mode to the first mode.

Abstract: An engine revolution in an expansion stroke of a cylinder is calculated, and stored, from a time that is required for a crank shaft to rotate by a predetermined angle from a compression upper dead center of that cylinder, and to determine the fuel injection amount, in averaging these stored revolutions from the cylinder immediately prior to a cylinder before the cylinder that is immediately prior to obtain a revolution that serves as the engine revolution, how many past cylinders are retroactively averaged is switched according to the engine operation state.

Abstract: An apparatus for the transmission of a deflection of an actuator, in particular of a piezoelectric actuator of an injection valve, comprises at least one first lever device which has a first transmission element which transmits the deflection of the actuator. In this case, there is provision for at least one first spring element to be provided for guiding or mounting the first transmission element.

Abstract: The present invention relates to an internal combustion engine having a high pressure fuel injector (1) which is arranged in a common rail arrangement, in order to improve the accuracy over in particular a service life of a high pressure fuel injector (1), comprising at least one nozzle needle (5), which can be pressed with a pressing force against a valve seat (12), and at least one solid-state actuator (3) which acts on an actuating piston (23) and is connected directly to a rail pressure supply (7), wherein at least one hydraulic operative connection (22) between the actuating piston (23) and a differential piston (4), which is operatively connected to the nozzle needle (5), is provided in such a way that an activation of the solid-state actuator (3) acts directly on the actuating piston (23), thereby permitting a pressure increase by means of the actuating piston (23) above a rail pressure, which pressure increase, via the differential piston (4), counteracts the pressing force such that the nozzle needle

Abstract: An electromagnetic fuel injection valve device for an internal combustion engine is configured to carry out an energization to an electromagnetic coil of an injection valve actuator for a valve opening motion and additionally carry out a mid-term energization at a time interval between both an energization for valve opening of a previous fuel injection and an energization for valve opening of a subsequent fuel injection. A current of the mid-term energization is smaller than a current of the energization for valve opening motion and has the same direction as a direction of the current of the energization for valve opening motion.

Abstract: An engine system includes an intake system, an internal combustion engine, and an exhaust system. The internal combustion engine includes a fuel droplet generator, and a fuel injector configured to inject fuel directly into a combustion chamber of the internal combustion engine.

Abstract: A pushrod is slidably received in a slidably holding guide, which is formed separately from a valve body of a valve apparatus. A clearance is provided between an inner peripheral surface of a small diameter tube portion of the valve body and an outer peripheral surface of the guide. The clearance is provided to absorb deformation of the small diameter tube portion.

Abstract: The injector comprises a balanced metering servovalve to control a rod for the opening/closing of a nozzle. La servovalve has a valve body with a control chamber radially delimited by a tubular portion and fitted with an outlet passage that is opened/closed by an axially movable shutter. The servovalve is also integral with an axial stem, provided with a lateral surface, through which the outlet channel exits. The shutter is coupled to the stem in an axially sliding manner and, when it closes the outlet passage, it is subjected to substantially null axial fuel pressure. The outlet passage has a calibrated segment distanced from the shutter and close to a bottom wall of the control chamber. The calibrated segment is carried by an element fixed to the valve body in correspondence to an axial segment of the outlet passage.

Abstract: The invention relates to a fuel injector having an injector housing containing a pressure chamber from which highly pressurized fuel is injected into a combustion chamber of an internal combustion engine. A nozzle needle control chamber is provided in the housing such that a nozzle needle has its first end disposed in the nozzle needle control chamber. A second end of the nozzle needle lifts away from its seat as a function of the pressure in the nozzle needle control chamber. The pressure in the nozzle needle control chamber is controlled by a switching valve device which is equipped with a piezoelectric actuator that expands longitudinally when supplied with current. A valve piston is coupled to the piezoelectric actuator and has its free end of the disposed in a valve piston control chamber. The valve piston control chamber communicates with the nozzle needle control chamber.

Abstract: The present invention concerns a multi-cylinder engine comprising a throttle body (5) in which a throttle intake-air passage (6) is provided. A throttle valve (7) is arranged in this throttle intake-air passage (6). Attached to the throttle body (5) is an injector (8), a leading end portion (9) of which is arranged opposite to an interior area of the throttle intake-air passage (6) downstream of the throttle valve (7) and is opened to provided a liquid-fuel injection hole (10). An intake-air pressure sensor (15) is attached to the throttle body (5) together with the injector (8) and an intake-air pressure introduction passage (18) has an inlet (18a) provided by opening an inner peripheral surface of the throttle intake-air passage (6) upstream of the injector (8).

Abstract: An internal combustion engine having a fuel injector which functions as a positive displacement pump and dispenses an amount of fuel which is fixed for each and every operation of the injector, and a controller which controls the operation of the fuel injector. In response to an increasing engine speed and/or load the controller increases in amount the fuel delivered per engine cycle by increasing in number the occasions the fuel injector is operated per engine cycle. In response to a decreasing engine speed and/or load the controller reduces in amount the fuel delivered per engine cycle by reducing in number the occasions the fuel injector is operated per engine cycle.

Abstract: An electromagnetic valve for the dosage of fuel in an internal combustion engine; the electromagnetic valve is provided with: a cylindrical tubular valve body; an obturator, which is arranged within the tubular valve body and is mobile between an open position and a closed position; and an electromagnetic actuator to shift the obturator and comprising a coil arranged outside the tubular valve body, a fixed magnetic pole is arranged within the tubular valve body, a mobile keeper arranged within the tubular valve body, mechanically connected to the obturator and is adapted to be magnetically attracted by the magnetic pole when the coil is excited, a tubular magnetic armature arranged outside the tubular valve body around the coil, and a magnetic washer having an annular shape arranged above the coil between the tubular valve body and the tubular magnetic armature to guide the closing of the magnetic flow around the coil.

Abstract: With reference to FIG. 1, the present invention provides an internal combustion engine (10) comprising a variable volume combustion chamber (13); an air intake system (18,20,21) for delivering charge air to the combustion chamber (13); an exhaust system (17) for relaying combusted gas from the combustion chamber (13) to atmosphere; and a fuel injection system (19, 21, 22, 23, 24, 25, 26) for delivering fuel into the charge air for combustion therewith in the combustion chamber (13). The fuel injection system (19,21,22,23,24,25,26) comprises a fuel injector (19) which functions as a positive displacement pump and dispenses an amount of fuel which is fixed for each and every operation of the injector (19); and a controller (23) which controls the operation of the fuel injector (19). In response to an increasing engine speed and/or load the controller (23) increases in amount the fuel delivered per engine cycle by increasing in number the occasions the fuel injector (19) is operated per engine cycle.

Abstract: A fuel injection systems for direct-injection diesel engines, has a piezoelectric actuator contained in an injector body and acted on by a first spring mechanism so that it remains in contact with the injector body at one end and with a sleeve-like booster piston on the other. A nozzle body connected to the injector body has at least one nozzle outlet opening, and in which a stepped first nozzle needle an axially movable, and a second spring mechanism is contained inside the booster piston and the injection pressure hold the first nozzle needle closed. An outer control chamber communicates via at least one leakage gap with a fuel supply under injection pressure; fuel in the control chamber acts on the first nozzle needle in the opening direction. A large diameter rear region of the first nozzle needle is fitted into the internal chamber of the booster piston.

Abstract: A protective cover for an actuating drive, that can be used as universally as possible, for components (14, 16) of a contacting and/or sealing arrangement of the actuating drive. The sealing arrangement is embodied in a liquid-tight but gas-permeable manner and ends in a cavity on the outer side, the cavity being covered by a cover (28) held on the actuating drive by means of a catch connection (30, 32).

Abstract: An actuator for actuating a fuel injection valve has a piezoactuator, enclosed in an actuator housing unit (14, 16). The housing unit has a cylindrical actuator housing (14) which is elongate in its axial direction (A) and at least partially encased by an extruded plastic coat. The actuator housing unit (14, 16), in its encased area, is provided with a ventilation aperture (20) in which a ventilation element (22) produced from a microporous material is disposed.

Abstract: A piezoelectric actuator module having a piezoelectric actuator, fastened between an actuator head and an actuator foot, and having a sheath, surrounding the piezoelectric actuator, for electrical passivation, is proposed in which the sheath is an insulation guard layer that is joined by nonpositive and/or positive engagement, by means of a mechanical attachment, to attachment components in the region of the end faces of the piezoelectric actuator or of the actuator head and/or of the actuator foot.

Abstract: The present invention relates to an indirect-injection internal-combustion engine, notably a supercharged engine, in particular of spark-ignition type, that can run according to a burnt gas scavenging mode or to a conventional mode, comprising at least one cylinder (10) with a combustion chamber (12), at least two air intake means (14, 16), one (14) of the means being a burnt gas scavenging intake means and the other (16) being a fuel injection intake means, said means comprising each a pipe (18, 20) controlled by an intake valve (22, 24), at least one burnt gas exhaust means with an exhaust valve (34) associated with an exhaust pipe (36) and at least one fuel injection means (26).

Abstract: A fuel injector with an injector body is disclosed which has at least two separate function units that are largely independent of one another. The function units are reversibly joined to one another by a connecting element and at least one positioning pin. The two function units can be produced and tested separately, which greatly simplifies both the production process and maintenance of the fuel injectors and lessens the vulnerability of the fuel injectors to malfunction.

Abstract: A fuel injection device of an internal combustion engine includes a piezoelectric actuator and a valve element that are coupled to one another. The valve element has a pressure stage. An increase in the force acting on the piezoelectric actuator is interpreted as an actual opening of the valve element, and/or a decrease in the force acting on the piezoelectric actuator is interpreted as an actual closing of the valve element, and that these be taken into account at least part of the time in the controlling of the piezoelectric actuator.

Abstract: A method is provided for an engine capable of burning gaseous fuel, the engine also including a combustion chamber, a fuel supply system with at least one fuel tank, at least one intake valve, and at least one exhaust valve, an injector to directly inject gaseous fuel into the combustion chamber, and an exhaust oxygen sensor. The method comprises directly injecting fuel from the injector into the chamber at a variable supply pressure which decreases as fuel tank pressure decreases; and adjusting at least one of an injection time and duration based at least on said variable pressure and information from the exhaust oxygen sensor.

Abstract: A capacitive load is controlled by charging and respectively discharging by way of a load current, which is allowed to oscillate between a maximum default and a minimum default. The maximum default increases monotonously in a first step, remains essentially constant in a second step, and decreases monotonously in a third step during a charging process. The minimum default decreases monotonously in a first step, remains essentially constant in a second step, and increases monotonously in a third step during a discharging process. A variable temporal overlap of the third step of the charging process and the first step of the subsequent discharging process is provided to set a required degree of charging. This results in a high level of resolution and reproducibility of the control.

Abstract: A fuel injection valve comprises a valve seat, a movable valve element which is seated on or separated from the valve seat, and a nozzle member having a plurality of nozzle holes. At least one of the valve element and valve seat has a curved surface at a contact position where they contact with each other when the valve element is seated on the valve seat. Two or more of the nozzle holes are provided outside an intersection line of a virtual extension surface along a tangential line to the curved surface at the contact position and a surface of the nozzle member.

Abstract: A method for operating an internal combustion engine in which a valve needle of a fuel injector is adjusted from a closing position via an intermediate position to an opening position and back again. The adjustment is carried out with the aid of a piezoelectric actuator to which a trigger signal is applied. To reduce the contamination danger of the fuel injector and to keep wear of the valve needle low, the trigger signal for triggering the piezoelectric actuator has a greater slope steepness during the transition of the valve needle from the closing position to the intermediate position than during the transition of the valve needle from the intermediate position to the opening position.

Abstract: The invention relates to an injector for a common rail injection system of an internal combustion engine, having an injector housing, a valve element disposed in the injector housing, a sealing ring acting as a seal between a high-pressure region and a low-pressure region of the injector, and a support ring, disposed together with the sealing ring in an annular chamber between the injector housing and the valve element, for bracing the sealing ring, which is provided, in its underside remote from the sealing ring, with a plurality of relief grooves spaced apart in the circumferential direction and, in its outer circumferential edge, with a plurality of recesses spaced apart in the circumferential direction. The relief grooves and the recesses are disposed in offset fashion in the circumferential direction.

Abstract: A control method for a fuel injection system having a spill valve (20), a nozzle control valve (22) and a valve needle (12) which is engageable with a seating to control fuel injection, wherein the method comprises applying a first drive current signal (30) to the spill valve (22) to move the spill valve (22) into a closed state and applying a second drive current signal (40) to the nozzle control valve (22) to move the nozzle control valve (22) to an open state, thereby to lift the valve needle (12) from the seating to initiate a main injection of fuel. The first drive current signal (30) is modified so as to move the spill valve (20) to an open state during “a spill valve opening period” during which the second drive current signal (40) is modified to move the nozzle control to valve (22) from the open state to a closed state. As a result the valve needle (12) is seated to terminate the main injection of fuel.

Abstract: A fuel injector device, for injecting fuel into a combustion chamber of an internal combustion engine, has a nozzle valve and nozzle valve control assembly adapted to use a control valve and high pressure fuel in the fuel injector in order to actuate movement of the nozzle valve between an open position to inject fuel and a closed position to terminate fuel injection. The nozzle valve control assembly employs a pressure balancing control valve so that the fuel pressure exerts a zero net force on the control valve in a dimension along which the control valve moves. Thus, the actuation occurs independently of the fuel pressure. In addition, the actuator is operably connected to the control valve by at least a hydraulic linkage, where the hydraulic linkage compensates for changes in the actuator and the injector body due to changes in temperature.

Abstract: An injection system for injecting one or both of water and alcohol into an internal combustion engine comprising a system monitor, a control module and a mixture delivery system. The system monitor may have a parameter level display, the control module may be adapted to receive one or more user-supplied parameters and the control module may be further adapted to store the one or more user-supplied parameters. The control module may also be comprised of a plurality of connectors and at least one electrical signal generator. The system may also be comprised of electrical wiring and a mixture delivery system having a pressure source.

Abstract: A fuel injection system for an internal combustion engine is provided which includes a fuel injector equipped with an actuator and a nozzle needle. The actuator works to lift the nozzle needle to inject fuel into an internal combustion engine. A controller controls an operation of the actuator to change an amount of lift of the nozzle needle a given number of times for a target injection duration, thereby ensuring the uniformity of size of atomized particles of the fuel sprayed from the fuel injector.

Abstract: An injector drive device includes a power supply unit that is supplied with power from a battery mounted in a vehicle and generates a voltage higher than the voltage of the battery, and EDU having a drive unit that is supplied with power from the power supply unit and drives an injector. The drive unit is housed in a housing. The power supply unit is placed externally to the EDU, that is, externally to the housing, so that the housing need not be made large against heat generation of the power supply unit.

Abstract: A fuel injector comprising a hollow body for housing a metering valve with a calibrated pipe for outlet of the fuel from a control chamber. The calibrated pipe is normally kept closed by a shutter controlled by an electromagnet comprising a magnetic core and an electric coil housed in an annular slot of the core. The coil outer cylindrical surface forms a gap with the annular slot so as to be lapped by the fuel coming out of the calibrated pipe. The coil comprises a bobbin having a pair of appendages for supporting electric supply plugs, which are englobed at least in part in a block of non-magnetic material. The bobbin has a substantially cylindrical rib, one flange adjacent to an end portion of the plugs, and another flange having a smaller diameter that forms a passage for the fuel between the calibrated pipe and the gap.

Abstract: An air-cooled engine is hung and fixed under a rear part of a backbone of a body frame. The engine is disposed so that the center axis of a cylinder in its cylinder block extends approximately horizontally and so that its cylinder head is directed toward the front. A fuel injection device is located between an intake valve and an intake port in the cylinder head. An injection nozzle of the fuel injection device and an intake valve opening are placed at a short distance. While the vehicle is idling or running at low speed, the vicinity of the tip of an injector of the fuel injection device is cooled by assist air supplied from a throttle body through a secondary passage, and when the vehicle runs normally or at high speed, the fuel injection device is cooled by the wind that hits the cylinder head.

Abstract: An engine-mounted mechanical fuel pump for an internal combustion engine contributes to a stable operation of the engine, a reduction in the weight of the engine, and a reduction in the pump drive loss. The engine includes a cylinder head provided with intake ports and exhaust ports therein, and fuel injection valves for injecting fuel into the inside of a tubular intake air routing assembly connected to the intake ports. A fuel pump is provided on the rear side of a cylinder block and on the upper side of a crankcase, in an arrangement where the intake ports are formed to extend rearwardly and the exhaust ports are formed to extend forwardly from the cylinder head. In one embodiment, the fuel pump is provided on the front side of the cylinder block, where the intake ports are formed to extend forwardly and the exhaust ports are formed to extend rearwardly.