128 results about "Top dead center" patented technology

A sliding arrangement for use in an internal combustion engine is described, comprising a cylinder liner (1) and at least one piston ring (10), wherein the liner (1) has a through-bore defining an inner surface (S) which in turn defines three sections: a first section (2) near the end of the piston stroke, facing the cylinder head (at top dead center, TDC); a second, middle section (3); and a third section (4) near the end of the piston stroke, facing the crankshaft of the engine (at top dead center, TDC), wherein (i) the TDC section (2) of the liner (1) has a surface finish with a first roughness value defined by a structure of recesses and projections (“valleys” and “raised areas”); the middle section (3) of the liner (1) has a surface finish with a second roughness value defined by a structure of recesses and projections (“valleys” and “raised areas”);(1) the BDC section (4) of the cylinder liner (1) has a surface finish with a third roughness value defined by a structure of recesses and projections (“valleys” and “raised areas”), and the roughness value of the middle section (3) is significantly lower than the roughness value of the TDC section (2), and is defined by an essentially very smooth structure of recesses and projections (“valleys” and “raised areas”); and (ii) a ceramic coating (R) is applied to at least part of the contact surface of the piston ring (10) by the physical vapor deposition (PVD) process.

A powered fastener driver including: a rotary lifter rotatably supported within the housing and configured to sequentially engage the plurality of teeth to move a driver blade from a bottom-dead-center position toward a top-dead-center position; a drive unit configured to provide torque to the rotary lifter, causing it to rotate; a nosepiece defining a fastener driving channel, the fastener driving channel extending along a driving axis of the driver blade; a workpiece contact element movable relative to the nosepiece between an extended position and a retracted position; a sensor assembly including a first inductive sensor configured to detect a position of the workpiece contact element in one of the extended position or the retracted position; and a second inductive sensor configured to detect an angular position of the rotary lifter, wherein the first inductive sensor and the second inductive sensor are on opposite sides of the rotary lifter.

The invention provides a two-stroke piston engine integrated controller with high-reliability position estimation, which is characterized in that a motor Hall signal acquisition function is added on the basis of an engine crankshaft position signal acquisition circuit of a conventional engine control module. A crankshaft position signal redundancy switching logic of the two-stroke piston engine is designed based on an improved circuit, a groove pole position behind a top dead center is positioned in the operation process of the engine, synchronous correction of a Hall signal and a crankshaft position signal is achieved, and a conversion relation between a motor Hall signal and the crankshaft position signal of the engine is established. When the crankshaft position signal is abnormal, the engine timing control method based on the motor Hall signal can be automatically switched. According to the invention, the redundancy switching of the position signal of the two-stroke piston engine can be realized, so that the piston engine can still complete a set task without flameout when the crankshaft position signal is abnormal, and the reliability of a control system is greatly improved.

An apparatus and method for operating an engine. The apparatus includes a crankshaft trigger wheel coupled to a crankshaft and a set of sensors equipped to generate a crankshaft signal associated with an instantaneous speed of the crankshaft trigger wheel. A controller is configured to receive the crankshaft signal corresponding to the instantaneous speed, determine a minimum instantaneous speed for the crankshaft trigger wheel to overcome a top dead center (TDC), and predict a reverse rotation event for the engine when the instantaneous speed falls below the minimum instantaneous speed. After making the prediction, ignition of the engine is prevented prior to the reverse rotation event occurring.

A powered fastener driver and a driver system, the powered fastener driver including a driver blade movable from a top dead center position to a bottom dead center position for driving a fastener into a workpiece. The driver may include a lift assembly for providing a torque to move the driver blade from a bottom dead center position toward a top dead center position, the lift assembly including a rotary lift configured to be selectively engageable with the driver blade, the rotary lift having a plurality of lift pins and a roller disposed on at least one of the lift pins, wherein the roller comprises a plurality of cam portions defined by a cup-shaped recess having a first radius oriented parallel to the direction of rotation of the roller and a second radius perpendicular to the first radius, and wherein the driver blade comprises a lifting tooth having a crown disposed thereon, the crown portion is configured to engage with at least one of the plurality of cam portions.

A stand for a portable band saw, to which a portable band saw is attached, comprises a base, a mounting arm which is pivotally mounted about a pivot point through the base and to which the portable band saw is attached, and a return device configured to automatically return the mounting arm to a top dead center.

The application provides a methanol engine with an internal direct injection structure applied to the field of methanol engines, wherein the valve is directly installed in the interior of the cylinder, the methanol fuel can be directly atomized and injected in the interior of the cylinder, loss caused by injection of the methanol fuel in the intake pipe can be avoided, the first fuel injection is performed when the piston moves from the top dead center to 1 / 2 of the total stroke, the second fuel injection is performed when the piston moves to the bottom dead center position, the two fuel injections are performed in stages, the mixing effect of the two fuel injections can be enhanced by the disturbance of the air flow in the cylinder, the methanol fuel combustion efficiency is improved to a certain extent, fuel loss in the starting process of the methanol engine is reduced, the methanol fuel is fully combusted, the working efficiency is effectively improved, and the methanol engine is more economical and environmentally friendly.

Internal combustion engine control device (100) comprising a control unit that controls the operating conditions of an internal combustion engine (1) using a pulse output from a crank angle sensor (101) which detects a rotational state of a crankshaft (6) of the internal combustion engine (1) by detecting a plurality of convex teeth (7b) arranged in a radial direction on an outer periphery of a body part (7a) designed as a circular plate element of a pulse generator wheel (7, 7', 7") connected to the crankshaft (6), characterized in that the plurality of convex teeth (7b) has a plurality of short convex teeth (7b1) and a plurality of long convex teeth (7b2), each having circumferential lengths (B2) that are longer than the respective circumferential lengths (B1) of the body part (7a) at the short convex teeth (7b1), wherein the plurality of long convex teeth (7b2) is provided in a first arrangement area over a retard-side angular range of 90 degrees from a top dead center angular position (TDC) of the internal combustion engine (1) on a retard side, and over a lead-side angular range of 90 degrees from the top dead center angular position (TDC) on a lead-side, wherein in a predetermined positional mounting relation of the pulse generator wheel (7, 7', 7") the plurality of short convex teeth (7b1) is provided in a second arrangement area which, in the predetermined positional mounting relation, lies outside the first arrangement area, the control unit detects a rising edge of the pulse output or a falling edge of the pulse output, which is generated successively in time sequence, in accordance with the fact that the crank angle sensor (101) detects circumferential ends (7b11, 7b12, 7b21, 7b22) of a convex tooth from the plurality of short convex teeth (7b1) and the plurality of long convex teeth (7b2), an arithmetic processing operation performed by the control unit, comprising a first cranking process, which is an arithmetic processing operation performed upon detection of a pulse end by the control unit, which is one of the rising and falling edges of the pulse output generated in accordance with the crank angle sensor (101) detecting an end of a tooth that is one of the circumferential ends (7b11, 7b12, 7b21, 7b22) of the plurality of short convex teeth (7b1) and the plurality of long convex teeth (7b2), and a second cranking process, which is an arithmetic processing operation performed upon detection of the other pulse end by the control unit, which is the other of the rising and falling edges of the pulse output generated in accordance with the crank angle sensor (101) detecting another end of the tooth that is the other of the circumferential ends (7b21,7b22) from the multitude of long convex teeth (7b2).

Internal combustion engine method, comprising: operating an engine in a first mode, the first mode comprising: Confirming the cold start condition of the engine, determining that the boiling point of the fuel in the engine is lower than a threshold boiling point of the fuel, and In response to confirmation of the engine's cold-start condition and determination that the fuel boiling point in the engine is lower than a threshold fuel boiling point, starting the internal combustion engine via a starter motor at an initial cranking speed, while fuel is injected via fuel injectors for a number of combustion engine cycles since the first combustion engine cycle, and subsequently suspending operation of the starter motor and operating the engine via combustion; and Operating the engine in a second mode, the second mode comprising the following: In response to confirmation of the engine's cold-start condition and determination that the fuel boiling point in the engine is higher than a threshold fuel boiling point, the internal combustion engine is started at a second cranking speed while fuel is injected and the ignition spark is deactivated for the number of combustion engine cycles since the first combustion engine cycle, and subsequently the operation of the starter motor is suspended and the engine is operated via combustion, wherein the fuel boiling point is based on a fuel composition in the engine, wherein in the first mode the fuel injection involves initiating fuel supply at top dead center (TDC) of an intake stroke of a combustion engine cycle and terminating fuel supply at bottom dead center (BDC) of the intake stroke of the combustion engine cycle.and wherein, in the second mode, fuel injection includes initiating fuel supply at TDC of the intake stroke of the internal combustion engine cycle and terminating fuel supply at TDC of a compression stroke of the internal combustion engine cycle.

A rotor engine comprehensive bench test system and test method belong to the technical field of engine test. The system contains rotor engine, AC power dynamometer, main control unit and other groups of modules. The dynamometer can realize forward and reverse reversible rotation of the engine. The main control unit is provided with forward and reverse switching and three-stage alarm module. Each component is connected and communicated. Sensors, acquisition modules, analyzers and the main control unit are cooperatively networked. The test method sequentially completes bench building, system inspection, pre-starting verification, lubrication establishment, engine starting, top dead center searching, mechanical loss test, warming, full-range boundary monitoring, hot-state running-in, ECU online calibration and data evaluation. The combustion analyzer can calculate cylinder pressure parameters. ECU modified parameters take effect immediately. Data analysis covers power and economic indicators. The present invention solves the problem that existing benches cannot adapt to rotor engine tests, builds a safe and efficient comprehensive test platform and provides technical support for rotor engine research and development.

The application discloses a method and device for self-learning control of upper and lower dead point positions of a throttle valve, which comprises the following steps: driving a valve plate to a lower dead point position of the throttle valve, recording the minimum position of the valve plate, driving the valve plate to an upper dead point position of the throttle valve, and recording the maximum position of the valve plate; recording a first overshoot amount of the valve plate at the moment when the valve plate runs from the minimum position to the maximum position, and recording a second overshoot amount of the valve plate at the moment when the valve plate runs from the maximum position to the minimum position; based on the interval range from the minimum position to the maximum position, a plurality of test overshoot amount positions are set, and a plurality of test overshoot amounts generated when the valve plate runs at the plurality of test overshoot amount positions are recorded; the maximum value is selected from the first overshoot amount, the second overshoot amount and the plurality of test overshoot amounts, and based on the maximum value, the minimum position and the maximum position, the self-learned lower dead point position and the upper dead point position are obtained. The control method can effectively reduce the risk of impact on the mechanical upper and lower dead point positions.

A powered fastener driver includes a driver blade movable from a top-dead-center (TDC) position to a bottom-dead-center (BDC) position, and a drive unit providing torque to move the driver blade, the drive unit having an output shaft defining a rotational axis. The driver further includes a rotary lifter engageable with the driver blade and receives torque from the drive unit in a rotational direction for returning the driver blade from the BDC position toward the TDC position, an aperture defined within the lifter through which the output shaft extends permitting radial movement of the lifter relative to the output shaft between a first position and a second position, and a spring biasing the lifter to the first position. The lifter translates in a radial direction relative to the output shaft from the first position toward the second position from engagement with the driver blade while rotating in the rotational direction.

Engine starting system with: a starting device (2, 3) for transmitting an associated rotational force to a crankshaft (1a) of a power engine (1) in order to drive the crankshaft (1a); and a control device (4) for controlling the operation of the starting device (2, 3) in response to a start request from the power machine (1); where the engine starting system includes a rotation determination section (11) which is able to distinguish a direction of rotation of the crankshaft (1a); where a period of time during which the crankshaft (1a) rotates in a reverse direction while the engine (1) is stopped is referred to as a reverse rotation period, the control device (4) sets a reverse rotation period as a crank-start prevention period to prevent the starting device (2, 3) from driving the crankshaft (1a); and if the start request is generated during a reverse rotation period, the start device (2, 3) is operated on the basis of information from the rotation determination section (11) to drive the crankshaft (1a) when it is detected that the crankshaft (1a) has switched from a reverse rotation to a forward rotation, characterized by the fact that the starting device (2, 3) comprises a first starting device (2) which is permanently connected to the crankshaft (1a), and a second starting device (3) which has a coupling function which is able to be connected to the crankshaft (1a); and, if the start request is generated during a reverse rotation period, the control device (4) drives the crankshaft (1a) through one of the first start device (2) and the second start device (3) or both the first start device (2) and the second start device (2), wherein the control device (4) operates the second starting device (3) ahead of the first starting device (2) to drive the crankshaft (1a) when the crankshaft (1a) is driven using both the first starting device (2) and the second starting device (3); The control device (4) determines, on the basis of at least one piece of information from a rotational speed, a torque and a current of the first starting device (2), whether a piston of the engine (1) can extend beyond top dead center in a first compression stroke or not; and The control device (4), after it is determined that the piston can go beyond top dead center, switches from the second starting device (3) to the first starting device (2) to drive the crankshaft (1a).

A powered fastener driver including a driver blade movable from a top-dead-center position to a bottom-dead-center position for driving a fastener into a workpiece. A driver may include a lifting assembly for providing torque to move the driver blade from the bottom-dead-center position toward the top-dead-center position, the lifting assembly including a rotary lifter configured to be selectively engageable with the driver blade, the rotary lifter having a plurality of lift pins and a roller disposed on at least one of the lift pins, wherein the roller includes a plurality of cam portions defined by cup-shaped recesses having a first radius oriented parallel to a rotational direction of the roller and a second radius perpendicular to the first radius, and wherein the driver blade includes a lift tooth having a crown disposed thereon, the crown configured to be engaged with at least one of the plurality of cam portions.

The present invention relates to an alternative two-stroke reciprocating internal combustion engine and power system thereof which eliminates the intake and compression phases of four-stroke Otto engines, and injects the fuel and the oxidising agent at high pressure directly into the combustion chamber or a prechamber at approximately the moment when the piston is at the top dead centre (TDC), using oxygen and / or air as the oxidising agent and hydrogen-based fuels, synthetic fuels, biofuels, alcohols, natural gas and mixtures thereof. At the same time, a spark is applied or combustion is produced by self-ignition, and expansion occurs until the piston reaches the bottom dead centre (BDC). The piston then starts to rise, the mechanically or electrically actuated exhaust valve opens and exhaust is discharged until the TDC is reached again, thereby repeating the cycle.

A motion generation device is configured to generate motion of a slide of a press device including the slide to which an upper die is attached, a bolster on which a lower die is placed, and a servomotor configured to move the slide reciprocally in the up and down direction. The motion generation device includes a motion generation section. The motion generation section is configured to generate a derivative motion of the slide at a cycle time different from the cycle time of the standard motion of the slide, such that the derivative motion includes the same motion as a first region of the standard motion including at least from top dead center to the end position of the molding region, and the speed of the slide at top dead center of the derivative motion is the same as the speed of the standard motion.

The utility model discloses a diaphragm adjusting device of a diaphragm compressor under low-negative-pressure air inlet. The diaphragm adjusting device comprises a piston assembly, a crosshead assembly, an air distribution disc and an oil distribution disc. The three metal diaphragms are arranged between the gas side diaphragm cavity and the oil side diaphragm cavity in an overlapped mode, and the middle diaphragm is provided with a guide groove to be communicated with the leakage detection opening; the electromagnet is arranged on the surface layer, close to the diaphragm side, of the oil distribution disc; the piezoelectric ceramics are respectively fixed in the machine body assembly and are close to an upper dead center and a lower dead center of the crosshead assembly; the springs are fixed on the two sides of the machine body assembly, are insulated from the crosshead assembly and are used for triggering the piezoelectric ceramics; the electromagnets are electrically connected with the piezoelectric ceramics respectively; the switch is attracted and controlled by the electromagnet to switch on and off of a circuit; the slide rheostat is connected in series with the electromagnet to adjust the adsorption force; the spring impacts the piezoelectric ceramic when the crosshead assembly moves to the upper stop point and the lower stop point, current is excited to enable the electromagnet to attract the switch, and then power-on and power-off of the electromagnet are controlled.

To provide a lock mechanism used for a drain plug device and having a simpler structure.SOLUTION: The lock mechanism 57 has a turning part 53 turning around a turning shaft R1 by reciprocation of the operated part 7, and a transmission end part 54a provided at an end of the transmission part 54 and regulated to reciprocate in a linear direction, and the turning part 53 has a projection part 53b capable of reciprocating along an arc-shaped path. When the discharge port is in the open state, the projection portion 53b is disposed at the top dead point position or a position in the vicinity of the top dead point position, which is a position where the center of the projection portion R1 overlaps with an imaginary surface 54a including the rotation shaft V1 and parallel to the reciprocating direction of the transmission terminal portion center, so that even if a force in the backward direction is applied to the plug lid when the discharge port is in the open state, the rotation of the rotation portion 53 is restricted, and the transmission portion 54 can be locked in a state of being moved forward.SELECTED DRAWING: Figure 7

The invention relates to a compression ratio measuring system, method and device of a to-be-measured engine. The system comprises a liquid storage container, an image acquisition device and a computer device, the liquid storage container is communicated with the combustion chamber, so that the internal space of the liquid storage container and the combustion chamber form a containing space, the image acquisition device is connected with the computer device, and the containing space is used for containing liquid so that the liquid can be stored in the liquid when the crankshaft drives the piston to move in the air cylinder. The volume of the liquid in the liquid storage container is changed along with movement of the piston, the image acquisition device is used for acquiring images of the liquid in the liquid storage container, and the computer device is used for acquiring the images acquired by the image acquisition device, acquiring the maximum volume and the minimum volume of the liquid in the liquid storage container according to the images and displaying the maximum volume and the minimum volume. And determining the compression ratio of the to-be-tested engine according to the maximum volume and the minimum volume. By adopting the system, the upper dead center and the lower dead center of the piston do not need to be manually confirmed, and the measurement accuracy of the engine compression ratio is improved.

Internal combustion engine (3) which can be operated in a 4-stroke operating mode (4TBM) and in a 2-stroke operating mode (2TBM), - with an engine block (5) containing at least one cylinder (6) in which a piston (9) is arranged to be axially adjustable between a bottom dead center (BDC) and a top dead center (TDC), and which has at least one side opening (20) open to the cylinder (6) for the respective cylinder (6), - with a cylinder head (7) covering the respective cylinder (6) and having for the respective cylinder (6) an intake chamber (14), an exhaust chamber (15), at least one intake valve (22) for controlling an intake opening (23) connecting the intake chamber (14) to the cylinder (6) and at least one exhaust valve (24) for controlling an exhaust opening (25) connecting the exhaust chamber (15) to the cylinder (6), - with an inlet channel (21) connecting the inlet chamber (14) to the respective side opening (20), characterized in that - that the internal combustion engine (3) has a piston stroke adjustment (26) for changing an axial position of the bottom dead center (BDC) in the respective cylinder (6) which is configured such that the piston (9) locks the respective side opening (20) at bottom dead center (BDC) when the internal combustion engine (3) is operated in 4-stroke mode (4TBM), and opens the respective side opening (20) at bottom dead center (BDC) when the internal combustion engine (3) is operated in 2-stroke mode (2TBM).

A compressor system for a puncture repair kit with a piston which is driven by a motor via a crank mechanism, and a cylinder main body having a pump chamber, in which the piston is mounted movably from a bottom dead center to a top dead center in order to compress air. The cylinder main body is a plastic component. and has a metal insert in the region of the air outlet valve.

The invention discloses a gear position self-learning method, system and equipment of a gear shifting mechanism and a medium, and relates to the technical field of computers.The gear shifting mechanism comprises a reduction gear, a threaded lead screw, a gear shifting fork and a dog-tooth clutch, the reduction gear drives the gear shifting fork through the threaded lead screw to achieve combination and separation of the dog-tooth clutch so as to conduct gear shifting, the method comprises the steps that under the condition that gear position information of a gear shifting mechanism is abnormal, whether the driving state of a target vehicle meets a preset self-learning condition or not is determined; if the self-learning condition is met, the current position of the threaded lead screw is obtained; locked-rotor detection is carried out on the gear shifting mechanism from the current position of the threaded screw rod, and the actual total stroke of the threaded screw rod in the locked-rotor detection process is obtained; if the stroke deviation between the actual total stroke and the preset theoretical total stroke is smaller than or equal to the preset error threshold value, the position information of the actual top dead center and the actual bottom dead center serves as the updated gear position to be stored.

The invention provides an engine bench test electric control system and a control method thereof, and a driving mechanism has a driving state in which the driving mechanism is connected with a crankshaft of an engine to reversely drag the crankshaft, a load state in which the driving mechanism is dragged by the engine, and a separation state in which the driving mechanism is separated from the crankshaft. According to the engine bench test electric control system, a first sensor detects a passing signal of a feature point of a rotating encoder; the second sensor detects the cylinder pressure of the cylinder body, obtains the maximum value point of the cylinder pressure under the condition that the driving mechanism is connected with the crankshaft of the engine to reversely drag the driving state of the crankshaft, and determines the maximum value point of the cylinder pressure as a compression top dead center of the stroke of a piston in the cylinder body; the electronic control unit obtains an encoder type of the encoder in response to the pass signal, associates the pass signal with the compression top dead center to obtain a circumferential position of a feature point at a moment at the compression top dead center relative to the axis of the crankshaft, and writes the encoder type and the circumferential position to form configuration information.

The invention relates to the technical field of air compressor control, in particular to a gear knocking active control system and method of a reciprocating piston type air compressor, an electromagnet mechanism is integrated in a cylinder cover assembly, and an armature is arranged on a piston assembly; according to the displacement amount of the piston assembly, the reversing moment when the piston assembly reaches the top dead center is determined, and the current air gap length is obtained; according to the gas pressure signal in the cylinder of the air compressor, the reverse thrust of gas in the cylinder to the piston assembly is determined; at the reversing moment, a control instruction is generated according to the reverse thrust and the air gap length, the output electromagnetic attraction force of the electromagnet mechanism is adjusted, the reverse thrust is balanced through the electromagnetic attraction force, and therefore negative torque is eliminated, gear reverse impact is avoided, and efficient mute operation is achieved.

A method for controlling an internal combustion engine, said internal combustion engine comprising a cylinder designed to be able to undergo stratified combustion, said method comprising, for each combustion cycle, the steps of: a. determining (31) the number of injection and ignition patterns to be implemented, b. determining (32) the amount of fuel to be injected at each injection by dividing the amount of fuel to be injected in the combustion cycle by the number of patterns to be implemented, c. determining (33) the time of each pattern as a function of the crank angle, said time of each pattern being between the intake bottom dead center and the combustion top dead center of the combustion cycle, d. controlling (34) the fuel injection circuit and the ignition device to produce the patterns as a function of the crank angle, the amount of fuel to be injected for each pattern and the timing of each pattern.

The invention relates to a piston ring device for a hydrogen engine, which comprises a sealing system piston ring and a compression ring which are respectively arranged on an oil control ring and an oil scraping ring. Wherein the piston ring device is used for controlling the pressure rise caused by blow-by between a sealing system piston ring and a compression ring, so that the pressure between the sealing system piston ring and the compression ring is higher than the pressure in a combustion chamber of a cylinder, especially in a second part of a working stroke, namely between 60 degrees and 450 degrees after an ignition top dead center; preferably, the ignition top dead center is between 50 degrees and 540 degrees, preferably, the ignition top dead center is between 20 degrees and 540 degrees, and even more preferably, the ignition top dead center is between 0 degree and 540 degrees. These pressure conditions are achieved in an engine speed between 60 and 5000 revolutions per minute, preferably between 1500 and 4500 revolutions per minute, more preferably between 2000 and 4000 revolutions per minute, most preferably between 2500 and 3500 revolutions per minute.

A powered fastener driver includes a piston movable within the inner cylinder from a top-dead-center (TDC) position to a driven or bottom-dead-center (BDC) position. The piston has a diameter of less than 45 mm, and a stroke length of the piston between the TDC position and the BDC position measures greater than 60 mm and less than 90 mm.

The invention relates to a method of combusting a first liquid fuel and a second liquid fuel in an internal combustion piston engine, the first liquid fuel having a lower heating value than the second liquid fuel, wherein - a first liquid fuel is injected into a cylinder of the engine as a main fuel, which brings most of the energy into the process, so that the total amount of first liquid fuel delivered to the cylinder for one combustion stage is divided into at least two partial injections, wherein - the main injection of the first liquid fuel accounts for 70-95% of the total amount of the first liquid fuel, and - the start of the main injection occurs at the latest at 20°CA before the top dead centre position of the piston in the cylinder, - the pre-injection of the first liquid fuel accounts for 5-30% of the total amount of the first liquid fuel, and wherein - the start of the pre-injection occurs at 20-55°CA before the top dead centre position of the piston in the cylinder, and the pre-injection is formed by one injection event, and - a second liquid fuel is injected into the cylinder of the engine as a fuel assisting compression ignition, so that the start of the injection of the second liquid fuel occurs at 1-23°CA before the start of the injection of the main injection of the first liquid fuel.

Drive control device (50) for an internal combustion machine (20), the internal combustion machine comprising a fuel injector (21) configured to inject fuel, an intake timing variation mechanism (22) configured to control the opening / closing of an intake valve provided at an intake port, and an exhaust timing variation mechanism (24) configured to control the opening / closing of an exhaust valve provided at an exhaust port, wherein the drive control device comprises: a valve timing control unit (56) configured to perform a wetting reduction control to control at least one of the intake timing variation mechanism and the exhaust timing variation mechanism to reduce a fuel wetting quantity, which is a quantity of fuel adhering to a wall surface of the internal combustion machine facing an injection field in which the fuel is to be injected, by means of a counterflow blown back to the intake port when a request is made to reduce the fuel wetting quantity during a start of the internal combustion machine, wherein the valve timing control unit is configured to to execute no control other than the wetting reduction control in order to avoid advancing the intake valve opening timing before top dead center of the internal combustion engine's exhaust point during the first stroke after the internal combustion engine's start-up, and to implement the control as the wetting reduction control in order to advance the valve opening timing of the intake valve before the top dead center of the exhaust of the internal combustion engine during a second and later stroke after the start of the internal combustion engine.

A powered fastener driver includes a cylinder containing a pressurized gas, a piston within the cylinder and moveable from a top-dead-center position to a bottom-dead-center position, a driver blade moveably coupled to the piston for driving a fastener into a workpiece, and a lifter mechanism for providing torque to move the driver blade from the bottom-dead-center position toward the top-dead-center position. The powered fastener driver also includes a sensor configured to monitor a current draw of a motor of the lifter mechanism, and a controller is electrically connected to the motor and the sensor. The controller is configured to monitor the current draw of the motor, correlate, using an algorithm stored in the controller, the current draw to a pressure value. The controller is also configured to compare the pressure value to a predetermined pressure range and activate an indicator when the pressure value is outside the predetermined pressure range.