摘要:
The present invention finds application in hydraulically actuated valves, such as gas exchange valves, having a valve member that moves within a valve body between an open position and a closed position. In valves such as these, the valve member typically includes a valve surface that contacts a valve seat included on the valve body when moving to its closed position. However, the impact velocity when the valve surface contacts the valve seat can be quite high. This can lead to fatigue of the valve stem and can wear out the valve seat, both of which can shorten the effective life of the valve. Therefore, the present invention includes a hydraulic pulse generator for slowing movement of the valve member which includes the direction of a hydraulic pulse toward the valve member as the valve member moves from its open position to its closed position.
摘要:
A method of engine compression release braking includes an initial step of compressing gas in an engine cylinder. A compression release brake valve is then opened at least in part by fluidly connecting a brake actuator to a source of high pressure actuation fluid. Next, a valve closing timing that results a valve seating velocity that is less than a pre-determined velocity is determined. The compression release brake valve is then closed at the valve closing timing at least in part by fluidly connecting the brake actuator to a low pressure actuation fluid reservoir.
摘要:
It is becoming more common for diesel engine cylinders to include an engine compression release brake that can utilize energy built up in the cylinder to provide additional braking for the vehicle. The present invention utilizes a software diagnostic test that is stored in an electronic control module to detect defects in the engine compression release brakes. In particular, the present invention operates a first portion of the engine cylinders in a power mode and a second portion of the engine cylinders in a braking mode and compares a resulting fuel injector response or engine response to an expected value to determine if one or more of the engine compression release brakes are performing as expected.
摘要:
An enhanced warm-up operation mode operates a first portion of engine cylinders in a power mode and a second portion of engine cylinders in a braking mode. More fuel is injected into the powered cylinders in order to maintain engine speed and overcome the retarding force of the engine compression release brakes on the braking cylinders. The engine cycles through which cylinders are powered and which are braking during the warm-up procedure. The process reduces emissions, such as white smoke, that are common during cold start conditions.
摘要:
A method of engine compression release braking with avoidance of turbine overspeed is disclosed. Initially, an electronic control module determines whether a turbine overspeed condition is present. If an overspeed condition is present, then the blow down timing of an engine compression release braking event is advanced. The present invention is particularly applicable to preventing turbine overspeed for vehicles operating at higher altitudes while compression braking.
摘要:
An actuator for adjusting a clearance between an end of a valve and an end of the actuator. The actuator has a piston therein having a central bore of which a portion is threaded. The piston has an end and has a flat defined near the end. The actuator has a stem member positioned therein. The stem member has a central portion which is threadedly positioned within the threaded portion of the central bore. The stem member defines a first end and a second end, and a threaded portion is located near the second end. The first end of the stem member and the end of the piston has a predetermined length which is adjustable. The predetermined length is adjusted by threadedly rotating the stem member relative to the piston. A locking device fixes the predetermined length during operation of the engine.
摘要:
In many cases, intake and/or exhaust valves and fuel injector plungers are desirably placed in a predetermined condition prior to starting the engine. In hydraulic systems, leakage and thermal contraction can lead to pressure loss during a period of non-operation, thereby allowing the components to move away from the predetermined condition. Similar concerns arise with the use of residual electromagnetic force, which can decay over time. In the case of intake/exhaust valves, for example, such undesired movement can led to a potential collision between the valves and the engine piston during starting. This invention provides a system and method for presetting the engine and/or the components thereof to the predetermined condition just prior to starting the engine.
摘要:
The invention relates to a method and an arrangement for engine braking a four-stroke internal combustion engine. The engine has for each cylinder (2) at least one inlet valve (7) and at least one exhaust valve (9) for controlling communication between a combustion chamber (5) in the cylinder (2) and an inlet system (8) and an exhaust system (10) respectively. In accordance with the invention, the arrangement also establishes communication between the combustion chamber (5) and the exhaust system (10) in conjunction with the exhaust stroke and also when the piston (3) is located in the proximity of the its bottom-dead-center position after the inlet stroke and during the latter part of the expansion stroke. Communication of the combustion chamber (5) with the exhaust system (10) is effected upstream of the throttling device (13) provided in the exhaust system, this throttling device being operative to at least maintain the flow though exhaust system (10) during an engine braking operation, therewith not cause an increase in the pressure upstream of the throttling device (13).
摘要:
A method of calibrating a variable valve actuation system is provided. An engine valve is moved from a first position where the engine valve blocks a flow of fluid to a second position where the engine valve passes a flow of fluid. A valve actuator is actuated to prevent the engine valve from returning to the first position. A signal is transmitted to cause the valve actuator and to allow the engine valve to return to the first position. The return of the engine valve to the first position is determined. A time parameter indicative of an elapsed time between the transmission of the signal and movement of the engine valve to the first position is determined.
摘要:
An engine valve actuation system is provided. The engine valve actuation system includes an intake valve that is moveable between a first position to prevent a flow of fluid and a second position to allow a flow of fluid. A cam assembly is configured to move the intake valve between the first position and the second position. A fluid actuator is configured to selectively prevent the intake valve from moving to the first position. A source of fluid is in fluid communication with the fluid actuator. A directional control valve is configured to control a flow of fluid between the source of fluid and the fluid actuator. A check valve is disposed between the directional control valve and the source of fluid, only allowing fluid flow from the fluid source to the directional control valve. A bleed orifice may be disposed between the directional control valve and the source of fluid, in parallel with the check valve.