JPH0310032B2 - - Google Patents

Description

Detailed Description of the Invention [Industrial Application Field] The present invention relates to a fuel injection pump for an internal combustion engine, which has one passage connecting a pump working chamber of the fuel injection pump with one pressure relief chamber. , the flow of this passage can be controlled via an electromagnetically operated valve, which is configured as a flat-seated valve, the movable valve member of which is directly controlled by the pressure prevailing in the pump working chamber. It relates to a type of device that is subjected to an action in the closing direction.

[Prior Art] According to a fuel injection pump of this type known from U.S. Pat. It is placed adjacent to the work room. Such a solenoid valve serves as a stop valve for completely depressurizing the pump work chamber under certain operating conditions. The valve member of this solenoid valve is loaded in the opening direction by an opening spring.
In order to prevent this valve member from falling into the pump working chamber and for the purpose of limiting the opening stroke,
This valve member is connected via the head to the armature of the electromagnet by form-locking, in which case a cavity is formed on the end face of the armature, the edge of this cavity being the head of the valve member. It has an inward collar that engages the back of the part. This construction type is extremely expensive;
In addition, it increases the moving mass of the solenoid valve, which also reduces the response speed or increases the energy requirements.

[Problems to be Solved by the Invention] An object of the present invention is to provide a fuel injection pump of the type mentioned at the beginning with a simple structure that quickly and reliably reduces the operating noise of the internal combustion engine at low loads, especially during idling. This is to be reduced by the use of magnet valves.

[Means for solving the problem] The present invention solves this problem in the first claim.
The problem was solved by the characteristics shown in section 2. in this case,
The movable mass of the solenoid valve can be made extremely small. This is because the movable element of the electromagnet need only be constructed as a pressing member. According to such a configuration, the valve member can be moved independently and quickly and reliably switched to the closed position by the closing spring in order to provide a predetermined injection amount without reducing the amount of fuel injected by the fuel injection pump. , and the closing process is not dependent on pressure build-up in the pump working chamber.

[Embodiment] The present invention will now be explained with reference to the embodiment shown in the drawings: In the casing 1 of the illustrated distribution type fuel injection pump for a multi-cylinder internal combustion engine, a cam is connected to the cam by a drive shaft as is well known. The plunger 8 causes reciprocating motion and rotation at the same time through the disk, rollers, and the like.

This plunger 8 moves in an inner bore 10 of a barrel 9 which is fitted into the casing 1 and is closed at the upper end, forming a working chamber 11 in the upper part. A stationary valve body 12 is used to close the barrel 9, which together with a movable valve element 13 forms a relief valve for the pump working chamber. Valve member 13
is loaded by one closing spring 14,
This closing spring 14 brings the head 15 of the valve member 13 into close contact with the valve seat of the valve body 12. Pump work room 11
The head 15 is additionally pressed against the valve seat by the internal pressure. One relief passage 45 is controlled by this valve. This escape passage 45
opens into a closed fuel reservoir 46, which is at a lower pressure than that prevailing in the pump working chamber 11 during the discharge stroke.

The movable valve member 13 is operated by one electromagnet 17. This electromagnet 17 has a coil 18, a mover 19, and a core 20. This electromagnet 17
is screwed into the casing 1 of the fuel injection pump through the casing 21 into one sleeve 2
2, the valve body 12 is pressed onto the barrel 9, in which case a certain degree of expansion due to temperature changes is compensated for.

As is well known, the pump working chamber 11 is supplied with fuel from a suction chamber to which this suction passage 23 is connected via one suction passage 23, and this suction passage 23 is connected to a suction groove 24 formed on the circumferential surface of the plunger 8. controlled via. This suction groove 24 opens the suction passage 23 every time the plunger 8 takes a suction stroke.
The supply of fuel from the pump work chamber 11 to the engine cylinders also takes place in a known manner through a number of delivery lines corresponding to the number of cylinders from longitudinal holes, transverse holes and distribution channels (not shown) in the plunger 8.

In the embodiment shown in FIG. 1, when the coil 18 of the electromagnet 17 is energized during idle rotation and low load rotation, the movable element 19 is pulled downward toward the core 20 and pushes the movable valve member 13. During the discharge stroke of the plunger 8, the electromagnet 17 does not exceed the force in the pump working chamber 11 which acts on the valves 12, 13 in the closing direction. However, as soon as the plunger 8 opens the suction stroke, the electromagnet 17 overcomes the force of the closing spring 14 of the valve 12, 13 and opens this valve. During the next discharge stroke, no pressure buildup occurs in the pump working chamber 11, so that the valves 12, 13 remain in the open position, and a portion of the fuel conveyed by the plunger 8 is not injected and the plunger 8 One passage 45 through the aperture of
The fuel is guided into the fuel reservoir 46 through the fuel tank 46. As a result, the injection time within the engine is extended.

In other words, because a part of the fuel delivered by the plunger is not sent to the injection nozzle but to the fuel reservoir, the amount of fuel delivered by the plunger, in other words, the amount of fuel per unit time supplied to the injection nozzle, is reduced. decrease, so that the plunger has to deliver for a correspondingly longer time in order to supply the required amount of fuel. This results in an extension of the injection time. This elongation of the injection time causes a significant reduction in engine noise and, in short, causes the engine to rotate at a so-called slow speed. During the suction stroke of the plunger 8, a portion of the fuel in the fuel reservoir 46 flows back into the pump working chamber 11. This backflow takes place via the relief passage 45 and the valves 12, 13 or through one of the suction channels 24, in which case the relief passage 45 has a passage extension 47 leading into the bore 10 of the barrel 9. Must have. Electromagnet 17
can be controlled, for example, by a switch operated on the accelerator pedal, in which case the accelerator pedal position for idle rotation as well as low-load rotation causes a corresponding excitation of electromagnet 17.

The embodiment of FIG. 2 differs from the embodiment of FIG. 1 in that the fuel reservoir is constructed as a spring-loaded fuel reservoir 46'. This spring-loaded fuel reservoir 46'
One piston 4 loaded by a spring 49
Collaborate with 8. Whereas in the embodiment of FIG. 1 the reservoir volume depends on the elasticity of the fuel itself, in the embodiment of FIG. stipulated.

[Brief explanation of the drawing]

FIG. 1 is a vertical cross-sectional view of a first embodiment of the present invention, and FIG. 2 is a vertical cross-sectional view of a valve of the second embodiment. 1...Pump casing, 2...Drive shaft, 3...
...Front cam disc, 4...Cam protrusion, 5...Roller, 6...Coupling, 8...Plunger, 9...
... Barrel, 11 ... Pump working chamber, 12 ... Valve body, 13 ... Valve member, 14 ... Closing spring, 17 ...
...Electromagnet, 18...Coil, 19...Mover, 2
0... Core, 21... Magnet casing, 22...
Sleeve, 23... Suction passage, 24... Suction channel, 46, 46'... Fuel reservoir, 47... Passage extension, 48... Piston, 49... Spring.

Claims (1)

[Scope of Claims] 1. A fuel injection pump for an internal combustion engine, which has one relief passage connecting a pump working chamber of the fuel injection pump with one pressure relief chamber, and the circulation of this relief passage is electromagnetically controlled. controllable via an actuated valve, which is designed as a flat-seat valve, the movable valve member 13 of which is actuated directly in the closing direction by the pressure prevailing in the pump work chamber 11; In the valve receiving type, the movable valve member 13 is loaded in the closing direction by one closing spring 14, and can be controlled to open by an electromagnetic mover during idle rotation and low load rotation. , the movable element of the electromagnet is a valve member 1 movable by the excitation of the electromagnet.
3 in the opening direction, the force exerted by the armature combines the force of the closing spring 14 and the movable valve member 13
is set to be larger than the sum of the force of the fuel flow acting based on the pressure difference upon opening of the valve, and the pressure relief chamber is one closed fuel reservoir 46, 46'.
The fuel reservoirs 46, 46' are configured as follows.
With the opening of the movable valve member 13, the pump work chamber 1 is removed via one controlled relief passage 45, 47.
Fuel injection for an internal combustion engine, characterized in that part of the received fuel is received into the pump working chamber 11 during each suction stroke of the plunger 8 and is depressurized via this relief passage 45, 47 into the pump working chamber 11. pump. 2. Fuel injection pump according to claim 1, wherein the fuel reservoir 46' has a spring-loaded piston 48 as a flexible wall. 3. The fuel injection pump according to claim 1 or 2, wherein one throttle point is provided in the passage 45.