8603893 Volvo.Penta High-pressure pump

Illustration 1 g02789714
(1) Fuel Tank
(2) Fuel Overflow Pipe
(3) Injection Pipe
(4) Injection Nozzle
(5) Fuel Filter Air Vent Pipe
(6) Fuel Transfer Pump
(7) Fuel Filter and Water Separator
(8) Fuel Injection Pump
(9) Fuel Injection Pump Air Vent Pipe Fuel from the tank (1) flows in the passage as shown by the arrows, and is injected from the nozzle (4) via the fuel injection pump (8). Overflow fuel returns to the tank.The system includes filters and other concerns to protect from entrance of air, water, and dust.While the engine is running, fuel is fed into the injection pump (8) by the fuel feed pump (6). The fuel is first passed through the fuel filter and water separator (7) where any foreign matter is removed. The fuel camshaft actuates the injection pump and force-feeds fuel to the injection nozzle (4) through the injection pipe (3). Fuel is then sprayed through the nozzle into the combustion chamber. The fuel discharged after lubricating and cooling the injection nozzle is returned to the fuel tank automatically through the overflow pipe (2).Two Stage Type Fuel Injectors
Illustration 2 g03370011
(10) Edge Filter
(11) Nozzle Holder Body
(12) First Stage Injection Pressure Adjusting Shim
(13) First Spring
(14) Pressure Pin
(15) Spring Seat
(16) Second Stage Injection Pressure Adjusting Shim
(17) Second Spring
(18) Pre-lift Adjusting Spring Seat
(19) Chip-packing
(20) Max-lift Adjusting Washer
(21) Retaining Nut
(22) Nozzle Exhaust and noise regulations are becoming increasingly strict, particularly in regard to the reduction of NOx (nitrogen oxides) and particulates.The two-spring nozzle holder has been developed to reduce NOx (nitrogen oxides) and particulates from direct injection diesel engine exhaust.The two-spring nozzle holder limits needle valve lift at initial valve opening to throttle the injection quantity. Main injection occurs when the in-line pressure has increased sufficiently to move the needle valve through full lift.This feature gives the following benefits:
Improved engine stability at low and intermediate speeds.
Decreased engine hunting and surge.
Decreased noise at idling.
Decreased idling speed because of improved engine stability.
Stabilized fuel injection characteristics from the injection pump and nozzle system, and easier matching of governor characteristics to engine demand.Fuel Injection Pump
Illustration 3 g03370014
(A) From Fuel Transfer Pump
(B) To Injection Nozzle
(23) Delivery Valve Holder
(24) Dumping Valve
(25) Delivery Valve Spring
(26) Delivery Valve
(27) Plunger Barrel
(28) Plunger
(29) Plunger Spring
(30) Tappet Roller
(31) Control Rack Pump Element
Illustration 4 g03411215
View of injection control in engine stop position
(32) Slot
(33) Plunger
(34) Control rack
(35) Delivery chamber
(36) Feed hole At the engine stop position of the control rack (34), slot (32) on the plunger align with feed hole (36). Fuel is fed to the delivery chamber (35) through the feed hole. The pressure in the delivery chamber does not build up and no fuel is forced into the injector nozzle.
Illustration 5 g03411216
View of injection control at fuel delivery position
(32) Slot
(33) Plunger
(34) Control rack
(35) Delivery chamber
(36) Feed hole
(37) Control groove At the fuel delivery position of the control rack, plunger (33) is rotated by control rack (34). Feed hole (36) is closed when the plunger is pushed up. The pressure in the delivery chamber increases, and fuel is forced into the injection nozzle until control groove (37) meets feed hole (36).Delivery Valve
Illustration 6 g03370181
(39) Valve
(40) Seat Surface
(41) Valve Seat
(42) Relief Plunger The delivery valve consists of the valve (39) and valve seat (41).The delivery valve performs the following functions:Reverse flow-preventing function. If the fuel flow reverses from the injection nozzle side when the plunger lowers, the time lag between the next delivery start and the nozzle injection start increases. To avoid this action, the delivery chamber to injection pipe interruption by valve prevents this reverse flow, thus keeping fuel always filled in the nozzle and pipe.Suck-back function. After completing the fuel delivery, the valve lowers, and the relief plunger (42) end contacts the valve seat (41). The valve further lowers until the seat surface seats firmly the delivery valve seat. During this time, the amount of fuel corresponding to (A) is sucked back from inside the injection pipe and the pressure inside the pipe is reduced. This state leads to an improved injection shut off and prevents after leakage dribbling.Dumping Valve
Illustration 7 g02793388
(A) At Fuel Injection
(B) At Fuel Return (A) At fuel injection. Since dumping valve is pushed up to press the spring, fuel is pressure-fed to injection nozzle the same as without dumping valve. (B) At Fuel Return. At fuel return by delivery valve after fuel injection, fuel returns through dumping valve orifice. Generally second injection is apt to occur by reflex pressure due to reaction of sudden pressure drop when changing into fuel return by delivery valve from high injection pressure. As a result of preventing this second injection perfectly by dumping valve and dissolving nozzle clogging, durability of injection nozzle is improved. Governor