The
Camshaft is composed of a journal, a CAM, a timing
Gear or a sprocket mounting part. The journal supports the camshaft to rotate smoothly, the CAM is distributed according to the law, and its contour determines the opening and closing time, lift and duration of the valve, and is specially treated to wear resistance. The timing gear or sprocket mounting position ensures precise transmission with the crankshaft.
Function:
Accurate control of valve opening and closing, reasonable valve control has a great impact on engine intake, exhaust and combustion, and can ensure the performance of the engine in different working conditions. Through the precise transmission ratio with the crankshaft, the engine strokes are maintained in order.
The working principle:
The crankshaft drives the camshaft to rotate. In an overhead camshaft engine, for example, the CAM pushes the
Rocker Arm to open the valve, and then the valve is closed under the action of a spring. The CAM profile determines the speed and lift of the valve opening and closing. The top rod engine has more tappets and push rods to transmit power, and the principle is similar.
Common types
Overhead camshaft (OHC), located above the cylinder head, improves response and fuel economy. The bottom camshaft (OHV), at the bottom of the engine block, is simple in structure but poor in high speed performance. According to the number of cams, the single overhead camshaft (SOHC) controls the intake and exhaust valves, which has a simple structure. Dual overhead camshaft (DOHC) two shafts separately control the intake and exhaust for high speed performance.
Maintenance points:
Regular check CAM and journal wear, wear serious need to replace. Ensure good lubrication and change oil and
Filter as required. Check the timing system, including chain, strap tension and variable timing mechanism. Pay attention to abnormal engine sound, check camshaft failure in time.
