Injection device for an internal combustion engine

Abstract

An injection device for an internal combustion engine includes a fuel delivery pump and a high-pressure pump which are connected to one another via a low-pressure fuel line. A high-pressure accumulator is connected to the high-pressure pump. At least one injector is connected via a high-pressure fuel line to the high-pressure accumulator. The injection device also has at least one fuel return line which is connected to the high-pressure accumulator and/or to the at least one injector. The fuel return line issues into the low-pressure fuel line which connects the fuel delivery pump and the high-pressure pump to one another. At least one air bleed valve is arranged in the course of the low-pressure fuel line or on the high-pressure pump or on a filter housing.

Claims

1. An injection device for an internal combustion engine, the injection device comprising: a fuel delivery pump and a high-pressure pump connected to one another via a low-pressure fuel line; a high-pressure reservoir connected to said high-pressure pump; at least one injector connected to said high-pressure reservoir via a high-pressure fuel line; at least one fuel return line connected directly to a leakage connection of said at least one injector; at least one air bleed valve disposed at a location selected from the group consisting of a course of said low-pressure fuel line directly upstream of said high-pressure pump, and at a low pressure side in said high-pressure pump; said at least one fuel return line issuing into said low-pressure fuel line in between said at least one air bleed valve and said fuel delivery pump; said at least one air bleed valve being a Schrader valve or a hydraulic coupling and said at least one air bleed valve including an actuator for automatically opening and/or closing said at least one air bleed valve.

2. The injection device according to claim 1, wherein said at least one air bleed valve is a 2/2-way valve or a 3/2-way valve.

3. The injection device according to claim 1, which comprises a fuel filter disposed inline in the course of said low-pressure fuel line connecting said fuel delivery pump and said high-pressure pump to one another.

4. The injection device according to claim 3, wherein said at least one air bleed valve is integrated into said fuel filter or is arranged between said fuel filter and said high-pressure pump.

5. An arrangement for bleeding an injection device, the arrangement comprising: an injection device according to claim 1; a collecting container for collecting fuel; and a line leading from an outlet of said at least one air bleed valve into said collecting container for delivering fuel from said at least one bleed valve to said collecting container at an end of a bleeding process.

6. The arrangement according to claim 5, wherein said collecting container is configured to be operated with vacuum pressure.

7. The arrangement according to claim 5, which comprises a suction pump disposed in said line between said air bleed valve and said collecting container.

Description

BRIEF DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWING

(1) It is particularly expedient to embody injection devices for diesel engines in the manner described if the internal combustion engine on which the injection device is used is a diesel engine. This is due to the fact that, on the one hand, diesel engines cannot generally manage without a return line and that other ways of bleedingvia the injectors into the combustion chambers of the engines, for exampleare virtually impossible to implement in diesel engines. The illustrative embodiments of the invention are explained in greater detail below with reference to two FIGS. 1 and 2, of which:

(2) FIG. 1 shows a schematic illustration of an injection device having an air bleed valve with spring return, and

(3) FIG. 2 shows a schematic illustration of an injection device having an air bleed valve arranged on a T-piece.

DESCRIPTION OF THE INVENTION

(4) FIG. 1 shows an injection device of an internal combustion engine, which, in the present case, is a diesel engine. The injection device has a fuel delivery pump 2, which is arranged in a fuel tank 1 and is connected by a low-pressure fuel line 4 to a high-pressure pump 6 lubricated with engine oil. A fuel filter 3 is arranged in the course of the low-pressure fuel line 4. Directly ahead of the high-pressure pump 6, the injection device has a volume flow control valve 5 arranged directly on the high-pressure pump 6. Moreover, the injection device comprises a high-pressure reservoir 8, which is connected on the inlet side to the high-pressure pump 6 by a high-pressure fuel line 6.1, wherein a check valve 7 that opens in the delivery direction is arranged in the high-pressure fuel line 6.1. Furthermore, the injection device comprises a pressure regulating valve 9, which is arranged on the high-pressure reservoir 8 and the outlet of which is connected to a fuel return line 11. The fuel return line 11 issues into the low-pressure fuel line 4. Finally, the injection device has four low-leakage injectors 10, which are each connected on the inlet side to the high-pressure reservoir 8 by a high-pressure fuel line 8.1, wherein each of the injectors 10 has a leakage connection 10.1 connected to the fuel return line 11 issuing into the low-pressure fuel line 4.

(5) In one embodiment of the injection device, provision is made for the fuel return line 11 to issue into the fuel filter 3 arranged in the course of the low-pressure fuel line 4.

(6) The high-pressure pump 6 is a pump that is driven by a camshaft of the internal combustion engine and is supplied with a sufficient quantity of engine oil for lubrication through arrangement on the camshaft and, in particular, does not require fuel lubrication and a dedicated lubrication circuit.

(7) Arranged in the low-pressure fuel line 4, between the fuel filter 3 and the volume flow control valve 5 is an air bleed valve 12 with spring return, on which there is arranged a push button for actuation, by means of which the air bleed valve 12 can be moved into the bleeding position in an actuating direction 16 for opening.

(8) In a special embodiment of the injection device, the air bleed valve 12 can also be integrated into the fuel filter 3 or arranged on a filter housing. At any rate, it is preferably arranged just ahead of or in the high-pressure pump 6, preferably on a low-pressure side, i.e. directly ahead of the volume flow control valve 5.

(9) In another embodiment, an electric actuator (not shown), which is embodied as an electromagnetic relay, is provided for actuation, i.e. to move the air bleed valve 12 into the bleeding position or to move it into an initial position.

(10) If there is air in the injection devicee.g. after the fuel tank 1 has been emptied or before first putting the internal combustion engine into operationthis injection device can be bled as follows:

(11) For this purpose, the air bleed valve 12 is moved into the bleeding position, and the fuel delivery pump 2 is actuated, e.g. by turning the ignition key to a first position or automatically through the actuation of the air bleed valve 12. As a result, the fuel delivery pump 2, which can be embodied as a vane pump, pumps fuel out of the fuel tank 1 into the low-pressure fuel line 4. The fuel delivered displaces air bubbles which may have accumulated in the low-pressure fuel line 4 or in the fuel filter 3 arranged in the course of the low-pressure fuel line 4 and takes said bubbles along, pushing them ahead of itself, through the rest of the low-pressure fuel line 4. The air bleed valve 12, which, in the present case, is designed as a 3/2-way valve, is moved in movement direction 16 into the bleeding position by pressing the pushbutton or through electric actuation. As a result, the fuel delivered to remove air discharges the air bubbles pushed ahead of it via an outlet 12.1 of the air bleed valve 12. It is expedient if this outlet 12.1 is connected to a collecting container 15, e.g. by means of a hose 14. The fuel which emerges during bleeding thus collects in the collecting container 15, which is held under the outlet 12.1 of the air bleed valve 12 for example. To facilitate bleeding, a suction pump 13 can be arranged in the course of the hose 14. The collecting container can also be put under pressure. In the illustrative embodiment under consideration, the air bleed valve 12 blocks the low-pressure fuel line 4 in the direction of the high-pressure pump 6 during the bleeding process.

(12) The air bleed valve 12 remains in the bleeding position until there is no longer any air escaping via the outlet 12.1 of the air bleed valve 12 and only bubble-free fuel is emerging. When the pushbutton is released, the spring-loaded air bleed valve 12 moves into the initial position (closed position). In the other embodiment mentioned, the air bleed valve can be moved back into the initial position in a corresponding manner through actuation by the actuator.

(13) The injection device illustrated in FIG. 2 corresponds very largely to the injection device described above with reference to FIG. 1, and the repeated features are again denoted by the same reference signs. The only difference relative to the first illustrative embodiment is due to the fact that the air bleed valve 12 is embodied as a 2/2-way valve and that a T-piece is arranged in the course of the low-pressure fuel line 4 in order to connect the air bleed valve 12 to the low-pressure fuel line. The 2/2-way valve can be a Schrader valve or a hydraulic coupling or, once again, can be a manually or electrically actuated valve.

(14) Removal of air from the injection device in FIG. 2 is accomplished as in the illustrative embodiment described above, but the actuation of the 3/2-way valve is replaced by the opening of the 2/2-way valve.