Fuel pump assembly of the common fault analysis

The technical status of the fuel system has a direct impact on the starting performance, dynamic performance and economic performance of the diesel engine. High-pressure pump assembly if there is failure, diesel engine will result in the corresponding failure phenomenon. Now fuel injection pump assembly failures are as follows:

1 injection pump plunger card reason

Single gear rack and pinion injection pump used in 175,180,1105, X195 and other diesel engines, this pump than single pump series I pump installation is complicated, easy to produce plunger jamming phenomenon, the reasons for this phenomenon Have:

(1) positioning screw length, screw the plunger sleeve tight crooked, so that the plunger stuck dead astringent. A copper washer may be padded under the screw so that the tail of the screw is stuck in the crescent-shaped groove of the oil return hole of the plunger sleeve so that the plunger sleeve can move up and down without turning left and right.

(2) The plunger sleeve on the pump body bearing surface is uneven, the plunger sleeve is squeezed out by the valve seat, then skew and pump body is not the same heart, at the same time due to uneven force on the plunger sleeve, so that the plunger Deformation, causing the plunger stuck. Milling plane can be flat, padded steel washers, restore the original height.

(3) rack in the groove is not flexible, mostly due to tooth rack and other parts of bumps, or gear and gear teeth, to find out the specific parts, with a small file repair.

(4) When replacing the pump gear, check the height of the shoulder on the gear by placing the gear in the pump body, which should be lower than the shoulder in the pump body. In this way, the plunger spring can be pressed against the shoulder in the pump body without being pressed against the gear shoulder. If the gear shoulder is pressed, gears, rack bar will rotate ineffective, the plunger also will not work well. Use a rasp to lower the gear shoulder file.

2 throttle rod moving resistance is too large, resulting in inefficient fuel control, diesel engine speed easily lost control or instability

The reasons for the failure are as follows: the plunger is issued in the plunger sleeve; the top of the set screw is too tight to deform the plunger sleeve; the fuel is not clean and the plunger is stuck; the rod (or the gear rod) With the gap is too small; bending deformation of the rod, the bearing end of the partial wear; output valve compression screw installation torque is too large, so that the deformation of the plunger; plunger adjusting arm and fork, ring gear and rack movement card; Plug adjusting arm and plunger spring seat pressed without active clearance, or with the rolling body phase and so on. Throttle rod movement is not flexible is a common fault, sometimes a single cause, sometimes caused by multiple reasons, to be carefully checked when troubleshooting.

3 uneven supply of fuel, unstable

The reasons for the failure are: air circuit; insufficient supply of oil pump pressure (check the oil pump inlet and outlet valves and filters, pressure regulating valve); multi-cylinder fuel injection pump plunger, the valve Pieces are not the same group, the sealing is inconsistent; plunger failed the quality of parts, especially the acute angle and chute edge does not meet the technical conditions, so that not only affects the fuel supply uniformity and stability of the plunger, But also has a significant impact on the start of the oil supply and stop the crispness of the oil supply. The tapered surface of the oil outlet valve is worn so that the sealing performance is not good. The relevant clearance of the oil volume control mechanism is too large, Agencies with the gap between the gap is too large; pump oil movement parts have jamming phenomenon. For multi-cylinder injection pump, it is particularly emphasized that, even with the same group number of the couple, the plunger pair and the valve must be sealed. If you use not the same number of the couple, the fuel supply characteristics of each cylinder will be inconsistent, it can not guarantee that the oil supply position should be the same degree of uniformity. In the repair, repair or replacement by grinding, must not be used with the old and new. To change must be replaced by the same group. If you do not know whether it is the same group, only through the oil characteristics of the test identified.

4 oil lever work jitter is too large, so that fuel supply is unstable, the engine speed is not stable, showing the bumpy ride phenomenon.

The cause of this fault is: the governor transmission buffer damage, or improper assembly tightness; tie rod and plunger adjusting arm, or gear and adjusting gear ring meshing gap is too large ); Camshaft bearing bearing clearance is too large; speed flywheel wear serious or quality does not match, or adjust the speed dial grind pits, or governor transmission end face beating too much. The above situation affects the degree of jerkiness of the throttle lever to varying degrees. Approach is: replace the substandard parts, strict control of assembly accuracy, so that the amount of jitter within the minimum. Jitter large, not only affects the stability of the working speed of the diesel engine, but also accelerate the wear and tear of related parts.

5 speed does not meet the requirements, such as stopping for high speed, or can not stop the fuel

The reasons for the failure are: serious wear of the plunger coupling (such as the adjusted can not meet the requirements of the oil, the plunger should be replaced); oil control mechanism gap is too large, especially with the linkage of multiple Gap formed by the cumulative total clearance is too large, so that the fuel control ineffective, the reaction lagged, resulting in speed does not meet the requirements; oil control mechanism of the moving resistance is too large, but also contributed to ineffective fuel control one of the reasons for the failure of Speed ​​control has a significant impact; fuel lever rod (or throttle lever) stroke is not enough, or improper adjustment, reflecting the relationship between the speed and the rod stroke does not match; high-speed stop fuel supply speed is too high, or stop the oil simply, to the Oil stop speed, there are still more fuel supply, reflected in the maximum idle speed diesel engine is bound to exceed the maximum speed limit requirements; high-speed rotation speed adjustment properly, so stop feeding speed is too high.

Under normal circumstances, where the larger even parts have been worn, the control mechanism transmission parts with the gap is too large, should be replaced with new parts and repair. Rely on adjustment can not fundamentally solve the problem. Such as the plunger has been severely worn, the nominal fuel quantity alignment, rod (rack) should be stopped to move to the position, still can not stop supply, this time can increase the rod stroke to stop, but the trip must not cut Increase too large, otherwise it will make the speed - oil rod deterioration, adversely affecting the load characteristics of the diesel engine. If the original rod stroke is not enough, it is possible to increase the stroke to change the amount of oil. If the itinerary has reached the upper limit of the prescribed range, it is generally not appropriate to adjust and increase it. If the rod stroke is enough, but its location is not suitable, generally by changing the lower fork and the relative position between the manipulator arm axis, or appropriate changes to the inner spring washer solution (referred to as the PB governor).

Speed ​​?? stiffness of the spring speed control more influential. By adjusting the shim can only change its assembly length (that is, adjust the assembly clearance or pre-tightening), adjust the equilibrium point of a certain force, and can not change its own stiffness. Therefore, if the governor spring stiffness is greater than or less than the allowable value of the range should be replaced with qualified springs. By adding and subtracting gasket adjustment may not be able to achieve satisfactory results.

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