Inspection of valve clearance of diesel engine:
There must be a certain gap between the valve and the rocker arm to ensure the sealing of the valve and valve seat and the appropriate opening of the valve, not affected by the thermal expansion and contraction of the transmission parts. If the valve clearance is too large or too small, it will affect the timing, lift or close tightness of the valve opening. In this case, the maintenance and repair of the diesel engine of the engineering machinery It is impossible to check and adjust the valve clearance.
The inspection method is a cold gap between the cold state of the diesel engine and the gap between the valve and the valve in the hot state of the diesel engine. The cold and heat clearance values are usually given in the instructions of the diesel engine, and the check and adjustment should be carried out in accordance with the value. When adjusting and adjusting, the cold inspection should be close to the big value and the thermal state is near the small value.
When the cold state is checked and adjusted, the diesel engine should be flameout at 30min at normal temperature. And both cold and hot, check and adjust the valve clearance must be completely closed when the valve is checked and adjusted and the valve tappet falls to the lowest position.
Adjustment method of valve clearance of diesel engine:
The inspection and adjustment of the valve clearance of the four stroke diesel engine is usually done by cylinder by cylinder and two times adjustment.
1 the cylinder by cylinder method is characterized by checking the order of the diesel engine's working order (for example, the 6 cylinder is 1-5-3-6-2-4,4 cylinder 1-3-4-2).
The specific operation method is to remove the cover of the valve chamber and rotate the crankshaft so that the first cylinder piston is located at the stop point on the compression stroke, so that the marks on the flywheel and the mark on the flywheel shell or the crankshaft pulley are marked with the cylinder body, and the first cylinder valve rocker arm is in free state, that is, the cylinder inlet and the exhaust valve are completely closed. At this time, the plug is used as a plug. When the gauge is inserted between the valve rod cap and the valve rocker arm, or the cam and the top of the tappet are inserted between the cam and the upper end of the tappet, a slight resistance is appropriate. If it is too loose or too tight, it should be adjusted. As for the selected gauge thickness, it should be in accordance with the clearance value specified by various types of diesel engines.
For the Cummins 6BT114 diesel engine, the machine determines the mark of the first cylinder at the stop point on the compression stroke, which is different from the above mark. This is because the diesel engine sets a timing pin near the injection pump at the timing gear room, presses the timing pin with the hand, and then slowly turns the crankshaft until the timing pin inserts the timing hole on the camshaft gear. The first cylinder piston is at the stop point of the compression stroke. After finding the first cylinder piston at the stop point on the compression stroke, the timing pin must be withdrawn to check and adjust the valve clearance. Otherwise, the timing gear will be locked and can not be rotated.
The Cummins NTC290 diesel engine is a 4 valve valve, that is, each cylinder has 2 inlet valves and 2 exhaust valves. The valve drive group mainly uses the same name valve bridge to manipulate 2 valves from the rocker arm. Therefore, the inspection and adjustment method of the valve clearance is different from common. The adjusting screws are set at the rocker arm and the valve head respectively.
The valve clearance is reflected between the rocker arm and the valve bridge top. In order to ensure that the valve bridge can force the force on the 2 same name valves at the same time, the valve bridge head should be adjusted to adjust the screw first. Then the rocker arm adjustment screw is then adjusted to realize the gap between the rocker arm and the valve bridge (i.e. the valve gap) within the specified range.
The concrete method is to turn the crankshaft and mark the mark 1-6TC on the crankshaft pulley. The first cylinder injector push rod is moved up, that is, the first cylinder piston is at the stop point on the compression stroke. At this time, the inlet and exhaust valve clearance of the first cylinder can be adjusted.
When the gap is adjusted, the screw nut is adjusted by the valve bridge head, and the adjusting screw is screwed out. Then the arm is pressed down with the finger to contact one end of the valve bridge and the top of a valve rod, then turn into the valve bridge head to adjust the screw and contact the top of the other valve. Keep the valve bridge adjusting screw, tighten and lock the nut. Insert the tape gauge between the valve rocker arm and the valve bridge. Unscrew the rocker arm to adjust the screw lock nut and turn the adjusting screw. Make the tape move a little resistance, stabilize the adjusting screw and lock the nut. Finally, check the gap again until the clearance meets the specified value.
2 the two times of rotation of the crankshaft for two weeks, all valve clearance can be checked and adjusted. This is determined by the working order of the diesel engine, the angle of the connecting rod journal, the actual opening and closing angle of the valve and the order of valve arrangement. For example, the 6135 diesel engine is at the stop point on the compression stroke in the first cylinder, and when both the inlet and the exhaust doors are in the closed state, the diesel engine can be found to be in the closed state. To check and adjust the valve clearance of the first cylinder, the other 4 valves can also be checked and adjusted, that is, the second, fourth cylinder inlet valve, the third, fifth cylinder exhaust valve.4 cylinder valve clearance inspection and adjustment method, similar to the 6 cylinder diesel engine described above. As for the power plant, engineering machinery and other equipment as the power, The difficulty of adjusting valve clearance of the source 12V135 diesel engine is that it is not easy to determine the working state of a certain cylinder. The practical examination and adjustment method of the valve clearance of the 12V135 diesel engine is introduced, and the practice proves to be effective.
12V135 diesel engine 12 cylinders in the form of V, each of the 6 cylinders, the cylinder order from the right front (facing the end of the flywheel) begins with the first, second, third, 4, 5, 6 cylinders. The left front (near the tank end) is seventh, eighth, ninth, 10, 11, 12 cylinders in turn. The left and right sides can essentially be considered as two independent 6135 firewood. Oil machine, the work order also meet the order of 6135 diesel engine work. The right 6135 diesel engine in order of doing the same order as the ordinary 6135 diesel engine, the 1-5-3-6-2-4. left 6135 diesel engine cylinder work order of 12-8-10-7-11-9, and also meet the 6135 diesel engine 1-5-3-6-2-4 work order, only the 12 cylinder as 1, from the back to the front. For this reason, the order of the work of the 12V135 diesel engine is to embed the sequence of two 6135 diesel engines into one another, that is, 1-12-5-8-3-10-6-7-2-11-4-9..
Because of the adjustment of the valve clearance of the 6135 diesel engine, most of the maintenance personnel are very familiar with. Therefore, the 12V135 diesel engine can be divided into two, as two 6135 diesel engines to adjust the valve clearance, so it is easier to master. The concrete method is that the 6135 diesel engine on the right is adjusted to the ordinary real 6135 diesel engine and can be adjusted by two times, that is When the first cylinder piston is at the stop point of the compression stroke, it is adjusted according to the method of "one in one row, two into three rows, four into five rows". Then turn the crankshaft 3600, at this time the sixth cylinder piston is at the stop point on the compression stroke, and other remaining valves can be adjusted.
The adjustment of the valve clearance of the 6135 diesel engine on the left is more complicated. This is because the 0 degree line on the 12V135 diesel engine flywheel corresponds to the top stop point of the first cylinder or the sixth cylinder piston of the right 6135 diesel engine, while the first cylinder (i.e. twelfth cylinder) or the sixth cylinder (or seventh cylinder) of the 6135 diesel engine on the left is at the top stop point at the upper stop point, and in the flywheel. In this way, the check and adjustment of the gap between the 6135 diesel engines on the left will cause great inconvenience. Therefore, it is obviously the most critical and difficult to find the stop point on the compression stroke of the twelfth cylinder or the seventh cylinder piston.
At this time, the method summed up according to the practical experience is to turn the flywheel in the direction of work and observe the instantaneous movement of the inlet and exhaust valves of the seventh cylinder, that is, the twelfth cylinder piston is at the stop point on the compression stroke. Then, the two adjustment method of the 6135 diesel engine valve can be adjusted. That is, when the twelfth cylinder compression stroke stops, "- (12)" is entered - (12). ) row, two (11) into three (10), four (9) into five (8) row "method to adjust. Then turn the flywheel 360. (that is, seventh cylinder compression stroke L stop). Adjust the remaining valve.
