EP2342449A1

EP2342449A1 - Injection system for an internal combustion engine

Info

Publication number: EP2342449A1
Application number: EP09784033A
Authority: EP
Inventors: Stephan Jonas
Original assignee: Continental Automotive GmbH
Current assignee: Continental Automotive GmbH
Priority date: 2008-10-16
Filing date: 2009-10-15
Publication date: 2011-07-13
Also published as: WO2010043678A1; CN202250536U; DE102008051931A1; US20120204834A1

Abstract

The invention relates to an injection system for an internal combustion engine (50), comprising an injector (22) that is hydraulically coupled to a field reservoir (16), a pump element (14) of a pump-nozzle arrangement or a pump-line-nozzle arrangement. The pump element (14) is adapted to feed fuel from a fuel tank (10) to the fuel reservoir (16), and the pump element (14) is mechanically coupled to a crankshaft (18) of the internal combustion engine (50) in such a way that the pump element (14) can be driven by the crankshaft (18).

Description

description

Injection system for an internal combustion engine

The invention relates to an injection system for an internal combustion engine.

For injecting fuels into combustion chambers of an internal combustion engine, in particular a diesel internal combustion engine, injection systems are used, which in recent years are increasingly designed as so-called "common rail" systems Injectors are supplied with fuel from a common fuel reservoir, the common rail, the fuel to be injected being present in the fuel reservoir at a pressure of up to more than 2000 bar.

Injection systems for internal combustion engines usually have different pumps, by means of which fuel is conveyed to be introduced into combustion chambers of the internal combustion engine. Such injection systems for internal combustion engines place high demands on the accuracy of the injection pressure required for injecting the fuel into the combustion chambers of the internal combustion engine.

This is particularly important as more and more stringent legislation is enacted regarding permissible pollutant emissions from internal combustion engines located in motor vehicles. These make it necessary to carry out various measures by which the pollutant emissions are reduced. For example, the formation of soot is highly dependent on the preparation of the air / fuel mixture in the respective cylinder of the internal combustion engine. It is it is beneficial for lowering pollutant emissions when the fuel can be injected very precisely into the cylinder.

From DE 101 32 732 Al a fuel injection system for an internal combustion engine is known, which has at least one local each injector associated pump element of a pump-nozzle unit or a pump-line-nozzle system for compression of the fuel depending on the number of cylinders. To a central fuel pressure accumulator injectors are connected.

The object of the invention is to provide an injection system for an internal combustion engine, by which operation of the internal combustion engine with very low pollutant emissions and a simple construction of the injection system are made possible.

The object is solved by the features of the independent claims. Advantageous embodiments of the invention are characterized in the subclaims.

The invention is characterized by an injection system for an internal combustion engine, with at least one injector hydraulically coupled to a fuel reservoir, a pump element of a pump-nozzle arrangement or a pump line-nozzle arrangement, wherein the pump element for conveying fuel from a fuel tank is formed in the fuel reservoir, and the pump element is mechanically coupled to a crankshaft of the internal combustion engine, such that the pump element is driven by the crankshaft.

This is particularly advantageous since it makes it possible to use a pump housing and a drive device for a high-pressure pump. pressure pump to dispense. Rather, the previously used pump element can be used in the injection system for the production of a high fuel pressure. It can be achieved in a simple manner, a uniformly high pressure of the fuel. In addition, no constructive reinforcement of the camshaft as in the pump-nozzle assembly o- the pump-line-nozzle arrangement is required. Furthermore, a compact construction and thus a high energy efficiency of the pump element are possible. Overall, a low weight and a low material requirement. As a result, the cost can be low.

In an advantageous embodiment of the invention, the injection system has a further pump element of a pump-nozzle arrangement or a pump-line-nozzle arrangement, the

Promotion of fuel from the fuel tank is formed in the fuel storage, and is mechanically coupled to the crankshaft of the internal combustion engine. The coupling is designed such that the further pump element can be driven by the crankshaft. The further pump element is arranged opposite to the pump element with respect to an axis of rotation of the crankshaft. This is particularly advantageous, since it is possible that the torque is small. With an unchanged high torque, in turn, a high fuel delivery volume can be achieved.

In a further advantageous embodiment, at least one of the pump elements is coupled directly to the crankshaft. This only a small space for the coupling of the pump elements to the crankshaft is required

In a further advantageous embodiment, the injection system has a volumetric flow control valve arranged upstream of the pump element and / or of the further pump element. valve, with which the flow of fuel into the pump element and / or the further pump element is adjustable. The volume flow control valve has a control which is hydraulically synchronized with the pump element and / or the further pump element. Thus, no inlet valve on the pump element is required, and a good controllability of the fuel flow into the pump elements is possible.

An advantageous embodiment of the invention is explained below with reference to the schematic drawing.

Show it:

Figure 1 is a block diagram of an injection system for an internal combustion engine, and

Figure 2 is a schematic view of an internal combustion engine.

Elements of the same constructions or functions are identified by the same reference numbers across all figures.

The injection system for an internal combustion engine 50 shown in FIG. 1 has a fuel tank 10 from which fuel is conveyed by means of a prefeed pump 12. The prefeed pump 12 is preferably designed as a vane pump. However, it can also be another type of pump, z. B. a gear pump or a gerotor pump can be used for the pre-promotion. The prefeed pump 12 can be mechanically driven by a drive shaft, not shown, which is coupled to a motor shaft of the internal combustion engine 50 (FIG. 2). Alternatively, however, it is also possible to use an electrically operated prefeed pump 12, whereby a control of the delivery rate of Vorför- derpumpe 12 is independent of the capacity of other pumps possible. In further embodiments, the pre-feed pump 12 can also be dispensed with. By a non-illustrated form control valve, the fuel pressure at the output side of the feed pump 12 can be limited.

Downstream of the feed pump 12, pump elements 14, 15 for conveying the fuel are arranged in a fuel reservoir 16. In further embodiments, only one of the pump elements 14, 15 may be arranged downstream of the prefeed pump 12. The pump elements 14, 15 are parts of a pump-nozzle arrangement or a pump-line-nozzle arrangement.

The pump elements 14, 15 are constructed essentially identical. The pump elements 14, 15 essentially consist of a housing 40, a pump chamber 42 arranged in the housing 40, a high-pressure piston 44 and a spring 46. The housing 40 is preferably part of an engine block 52 of the internal combustion engine 50 (FIG. 2). The high pressure piston 44 is axially movable in the pump chamber 42 of the housing 40 and is operatively connected to a crankshaft 18. The spring 46 is preferably supported on the housing 40 and the high-pressure piston 44.

In order to be able to fill the pump chamber 42 with fuel, it has an inlet line and an inlet valve 47 arranged in the latter, via which fuel can flow into the pump chamber 42. The pump chamber 42 further has a drain line and an outlet valve 48 arranged therein, via which fuel can be expelled from the pump chamber 42 in the direction of the fuel reservoir 16.

The pump elements 14, 15 are mechanically coupled directly to the crankshaft 18 of the internal combustion engine, so that they are driven by the crankshaft 18 and the space required for the coupling is very small. In further embodiments, between the pump elements 14, 15 and the crankshaft 18, a transmission lever can be arranged, with the forces between the pump elements 14, 15 and the crankshaft 18 can be well transferred. The further pump element 15 is relative to a rotational axis A of the crankshaft 18, the pump element 14 opposite, that is offset by 180 °, arranged.

The fuel reservoir 16 is hydraulically coupled to the pump elements 14, 15 via a fuel storage supply line 20.

The fuel reservoir 16 is further hydraulically coupled via lines to an injector 22 or to a plurality of injectors 22. Each of the injectors 22 is associated with a combustion chamber 53 (FIG. 2) of the internal combustion engine 50, and each injector 22 can be controlled so that fuel is injected into the combustion chamber 53 of the internal combustion engine 50. By the pump elements 14, 15, the fuel which is to be injected by means of the injectors 22 into the combustion chambers 53 of the internal combustion engine 50, reach a relatively high injection pressure.

Excess fuel may be returned to the fuel tank 10 from the injectors 22 via an injector return line 24.

Between the prefeed pump 12 and the pump elements 14, 15, a volume flow control valve 26 is arranged, with which the fuel flow from the feed pump 12 into the pump elements 14, 15 is adjustable. By means of a pressure sensor 28, through which the fuel pressure in the fuel reservoir 16 can be determined, and optionally in response to other input variables, the flow control valve 26 can be controlled so that a low-pressure side control of the pump elements 14, 15 supplied fuel flow is possible.

In a further embodiment of the injection system, in each case one of the volume flow control valves 26 is arranged between the prefeed pump 12 and the pump elements 14, 15, which is in each case hydraulically synchronized with the pump element 14, 15 associated therewith. In this configuration, the intake valves 47 may be omitted.

The pump elements 14, 15 are hydraulically coupled by means of a downstream of the pump elements 14, 15 and upstream of the fuel reservoir 16 branching return line 30 with a pressure control valve 32. The pressure regulating valve 32 can be actuated, for example, as a function of the fuel pressure in the fuel reservoir 16 determined by the pressure sensor 28. When a predetermined fuel pressure in the fuel reservoir 16 is exceeded, the pressure regulating valve 32 can open and part of the fuel delivered by the pump elements 14, 15 can be returned to the fuel tank 10 via the return line 30.

To protect the arranged in the injection units, in particular the pump 12 and the pump element 14, 15 and the control valves 22, 20, a filter 36 is provided between the fuel tank 10 and the prefeed pump 12.

The pressure regulating valve 32 is arranged in the return line 30, which is coupled on the output side to the injector return line 24 of the at least one injector 22. The return line 30 and the injector return line 24 from the domestic Jektoren 22 are preferably returned to the fuel tank 10.

FIG. 2 shows the internal combustion engine 50 with an intake tract 51, the engine block 52, a cylinder head 54 and an exhaust tract 56. The intake tract 51 preferably comprises a throttle valve 58, a collector 60 and a suction pipe 62. The suction pipe 62 is towards a Cylinder Zl is guided via an inlet channel into the combustion chamber 53 of the engine block 52. The engine block 52 further includes the crankshaft 18, which is coupled via a connecting rod 66 with a piston 68 of the cylinder Zl.

The cylinder head 54 includes a gas inlet valve 70 and a gas outlet valve 72 and the injector 22.

In addition to the cylinder Zl further cylinders Z2 to Z4 are preferably provided.

In the following, the function of the injection system for the internal combustion engine 50 will be briefly described:

The prefeed pump 12 delivers fuel from the fuel tank 10, wherein impurities in the filter 36 between the fuel tank 10 and the prefeed pump 12 can be retained. The fuel then passes to the volume flow control valve 26. By the flow control valve 26, the pump elements 14, 15 provided as much fuel as is required by the fuel tank 16.

If the volumetric flow control valve 26 has a control that is synchronized hydraulically with the pump elements 14, 15, then no intake valves 47 must be arranged in front of or in the pump elements 14, 15 and it is nevertheless necessary to provide a good control of the fuel flow in the pump elements 14, 15 possible.

As a result of a rotational movement of the crankshaft 18 in a direction of rotation R, the high-pressure pistons 44 in the pump chambers 42 are moved toward the axis of rotation A so that they are filled with fuel via the supply line and the open inlet valves 47.

By the further rotational movement of the crankshaft 18 in the

Direction of rotation R, the high pressure piston 44 are moved away from the axis of rotation A, that the located in the pump chambers 42 fuel is compressed. The compressed fuel is expelled from the pump elements 14, 15 via the drain line and the opened exhaust valves 48 and delivered to the fuel reservoir 16 via the fuel storage supply line 20. From the fuel reservoir 16, the fuel is supplied to the injectors 22, and injected from them into the combustion chambers 53 of the internal combustion engine 50.

The fuel pressure required for the fuel tank 16 is determined by the pressure regulating valve 32. If the pressure in the fuel storage supply line 20 and thus in the fuel storage 16 increases too much or if the pressure in the fuel storage 16 is to be reduced in a targeted manner, fuel can be discharged into the fuel tank 10 by means of the pressure control valve 32. In the fuel tank 10 further fuel from the return line 24 is returned from the injectors 22. Reference sign list

10 fuel tank

12 Pre-feed pump 14 Pump element

15 additional pump element

16 fuel storage 18 crankshaft

20 Fuel storage supply 22 Injector

24 injector return line

26 flow control valve

28 pressure sensor

30 Return line 32 Pressure control valve

36 filters

40 housing

42 pump chamber

44 high-pressure piston 46 spring

47 inlet valve

48 exhaust valve

50 internal combustion engine

51 Intake tract 52 Engine block

53 combustion chamber

54 Cylinder head 56 Exhaust tract

58 Throttle 60 collector

62 intake manifold

66 connecting rod

68 pistons

70 gas inlet valve 72 gas outlet valve

A rotation axis

R direction of rotation

Claims

claims

1. injection system for an internal combustion engine (50), with

at least one injector (22) hydraulically coupled to a fuel reservoir (16),

- A pump element (14) of a pump-nozzle arrangement or a pump-line-nozzle arrangement, wherein the pump element (14) for conveying fuel from a fuel tank (10) in the fuel reservoir (16) is formed, and the pump element (14) is mechanically coupled to a crankshaft (18) of the internal combustion engine (50), such that the pump element (14) can be driven by the crankshaft (18).

2. Injection system according to claim 1, with a further pump element (15) of a pump-nozzle arrangement or a pump-line-nozzle arrangement, which for the promotion of fuel from the fuel tank (10) formed in the fuel storage (16) is, and with the crankshaft (18) of the internal combustion engine (50) is mechanically coupled, such that the further pump element (15) by the crankshaft (18) is drivable, wherein the further pump element (15) relative to a rotation axis (A) the crankshaft (18) is arranged opposite the pump element (14).

3. Injection system according to claim 1 or 2, wherein at least one of the pump elements (14, 15) is coupled directly to the crankshaft (18).

4. Injection system according to one of the preceding claims, with a volume arranged upstream of the pump element (14) and / or of the further pump element (15). flow control valve (26) with which the flow of fuel into the pump element (14) and / or the further pump element (15) is adjustable, wherein the flow control valve (26) has a control which hydraulically with the pump element (14) and / or the other Pump element (15) is synchronized.