Patent ID: 8991350
Filing Date: 2015-03-31
Classification: F01L,F02D

Abstract:
1. A method for a reset rocker arm braking, comprising a process of utilizing an exhaust valve actuator of an engine to open an exhaust valve, the engine comprising an engine brake control mechanism, the exhaust valve actuator comprising a cam and a rocker arm, the cam comprising an exhaust cam lobe and at least one brake cam lobe, the exhaust cam lobe being higher than the brake cam lobe, the rocker arm being provided with a brake oil supply passage, and the method for a reset rocker arm braking comprises: arranging a brake piston bore opened downward at a lower side of one end of the rocker arm, slidably disposing a brake piston in the brake piston bore, the brake piston having an extended position and a retracted position in the brake piston bore, communicating the brake oil supply passage in the rocker arm with the brake piston bore, arranging a one-way oil supply valve between the brake piston bore and the brake oil supply passage or within the brake oil supply passage, the one-way oil supply valve having an oil supply direction from the brake oil supply passage to the brake piston bore, arranging an oil drain piston bore opened upwards at an upper side of the same end of the rocker arm, slidably disposing an oil drain piston in the oil drain piston bore, arranging an oil drain passage between the oil drain piston bore and the brake piston bore, wherein the process of utilizing the exhaust valve actuator of the engine to open the exhaust valve comprises the following steps: firstly, turning on the brake control mechanism, supplying oil to the oil drain piston bore and the brake piston bore simultaneously through the brake oil supply passage, placing the oil drain piston at a position for closing the oil drain passage and placing the brake piston at the extended position; then, utilizing the brake cam lobe of the cam to drive the rocker arm and the brake piston at the extended position to open at least one exhaust valve under the brake piston; and then utilizing a rising section at a top portion of the exhaust cam lobe which is higher than the brake cam lobe to keep driving the rocker arm, and at the same time, utilizing a motion of the rocker arm to change a position of the oil drain piston in the oil drain piston bore so as to open the drain oil passage to drain oil out of the brake piston bore, moving the brake piston from the extended position to the retracted position, and skipping a part of the actuation onto the exhaust valve from the top portion of the exhaust cam lobe; finally, utilizing a descending section of the exhaust cam lobe of the cam to drive the rocker arm to rotate backwards, utilizing the backward motion of the rocker arm to change the position of the oil drain piston in the oil drain piston bore so as to close the oil drain passage, and at the same time, supplying oil to the brake piston bore through the brake oil supply passage and the one-way oil supply valve, re-placing the brake piston at the extended position, and starting a new engine braking cycle.