KR101980363B1

KR101980363B1 - Common rail injection system for an internal combustion engine

Info

Publication number: KR101980363B1
Application number: KR1020147023145A
Authority: KR
Inventors: 토마스 슈미츠바우어
Original assignee: 콘티넨탈 오토모티브 게엠베하
Priority date: 2012-01-19
Filing date: 2013-01-09
Publication date: 2019-05-20
Also published as: WO2013107671A1; EP2766594A1; EP2766594B1; DE102012200764B3; KR20140117577A

Abstract

The present invention relates to a common rail injection system (100) for an internal combustion engine having a high pressure pump (500), a distributor pipe (600) and at least one injector (700), wherein the high pressure pump (500) Lt; RTI ID = 0.0 > fuel. &Lt; / RTI > Fuel can be injected into the combustion chamber of the internal combustion engine through one or more injectors fluidly connected to the distributor pipe. The injection system is characterized in that the injection system is fluidically arranged upstream of the high pressure pump and has an inlet valve (400) which allows the fuel flow to the high pressure pump to be selectively stopped for individual delivery cycles of the high pressure pump.

Description

[0001] COMMON RAIL INJECTION SYSTEM FOR INTERNAL COMBUSTION ENGINE [

The present invention relates generally to a common rail injection system in which strokes of individual pumps of a high-pressure fuel pump can be selectively activated / deactivated, or in other words, To selectively actuate and deactivate individual pump strokes of the high-pressure pump.

The term " Common Rail Injection Systems " refers to fuel injection systems for internal combustion engines in which a high pressure pump compresses fuel to a high pressure level, and the pressurized fuel is delivered to a distributor pipe Rail). The fuel supply is provided from the distributor pipe to the so-called injectors which cause the pressurized fuel to be injected into the combustion chambers of the engine at high pressure.

Conventional injection systems, for example, dedicated pressure lines for the supply of fuel from the injection pump to the injection nozzles of the cylinders for the individual cylinders of the internal combustion engine, in-line (not shown) In contrast to engines with in-line injection pumps or distributor injection pumps, the common rail injection system has a common high-pressure line. In this way, in contrast to conventional injection systems, the injection time and injection amount are controllable independent of the crankshaft angle of the engine. Through a common high-pressure line, the pressure required for injection is continuously supplied to the injectors. The pressure may be in the range of up to 250 MPa. Injectors in the common rail system function as electromagnetically or piezoelectrically actuated valves in which the fuel pressurized to high pressure is injected into the combustion chamber.

This technique allows multiple injections per actuation stroke of the cylinder whereas in contrast to conventional injection systems with in-line or distributor injection pumps only one injection per actuation stroke Lt; / RTI > This allows, for example, a pilot injection of a relatively small fuel amount, which allows smooth engine operation to be achieved. It is possible to reduce the nitrogen oxide content in the exhaust gas if, for example, the selective catalytic reduction (SCR) catalytic converters are made available by self-injection and post-injection. In addition, the post-injection appropriately increases the energy content (calorific value) of the exhaust gas, thereby enabling it to be used, for example, to enable burn-off of the soot particle filter when required.

In a common rail injection system, the high pressure pump provides the continuous fuel pressure as possible to the distributor pipe as a pressure accumulator. In a common rail injection system, utilization is made of the fact that the fuel, in particular the diesel fuel, exhibits a certain amount of compression, in order to at least partially absorb pressure peaks due to pump strokes of the high pressure pump. In addition, the volume of the distributor pipe serves as the volume of the pressure accumulator to flatten the pressure peaks. Here, the pressure peaks can be better compensated for the larger the accumulator volume of the pressure accumulator as the distributor pipe. On the other hand, larger volumes lead to greater inertia in the injection system, since the corresponding higher operating pressures must be made entirely in the rail system. However, the most extensive and possible compensation for pressure peaks in the rail system is necessary to avoid pressure waves in the injector that can uncontrollably affect the amount of fuel injected into the combustion chamber, respectively. This can have a negative effect on the efficiency of combustion.

To ensure a constant pressure supply as much as possible, the common rail injection system has a fuel recovery line from the rail system to the fuel tank. When a pressure that depends on the operating state of the internal combustion engine is made in the distributor pipe, excess fuel is recovered to the fuel tank through the pressure regulating valve. Here, the fuel is heated, which can lead to increased wear of the fuel-transfer parts. To prevent damage to the system, the fuel must therefore be cooled each time it is recovered, and additional system components such as fuel coolers should be provided for this purpose.

The high-pressure pump of the common rail injection system must ensure continuous fuel supply to all injectors in all operating states of the engine (idle, partial load, full load). For this purpose, the high-pressure pump is configured in terms of capacity, so that, at all times and in all operating states of the engine, the high-pressure pump can carry more fuel than the fuel required for operation of the internal combustion engine in its individual operating state. As a result, The high pressure pump has a considerably exceeded size for the average normal operating condition in order to be able to also ensure proper stocking for excess delivery in case of operation. However, increasing the size of the high-pressure pump also has the effect of having a larger energy demand that the latter must be provided by the internal combustion engine. This reduces the efficiency of the engine.

With this in mind, it is an object of the present invention to specify a common rail injection system that enables the proper supply of pressure to the injection system using a reduced-size high-pressure pump.

This object is achieved by the features of claims 1 and 6 according to the invention. Advantageous refinements of the invention are specified in the dependent claims.

The present invention therefore proposes a common rail injection system for an internal combustion engine having a high pressure pump, a distributor pipe and at least one injector, wherein the high pressure pump conveys fuel for operation of the internal combustion engine to the distributor pipe, The common rail injection system is distinguished by the fact that the injection system has an inlet valve arranged upstream of the high pressure pump in the flow plane, , Allowing the fuel supply to the high pressure pump by the inlet valve to be selectively stopped for individual delivery cycles of the high pressure pump.

With the injection system according to the invention it is possible to carry out an increase in the frequency of pump strokes of the high pressure pump without a significant increase in wear of the pump or without an increase in the frequency leading to a decrease in the service life of the pump. Pressure pump for selective transport cycles due to fuel supply to the high pressure pump in which the high pressure pump is to be stopped, through the provision of an inlet valve upstream of the high pressure pump, to compensate for the rise in pump duty frequencies, free state.

Thus, for a given piston volume of a high pressure pump, the number of pump strokes can be provided, for example, double or quadruple. This can be achieved, for example, by doubling or quadrupling the number of stroke cams of the camshaft of the high-pressure pump. This results in a corresponding increase in the volume of fuel being provided, at full load operation of the internal combustion engine. According to the present invention, without providing an inlet valve upstream of the high-pressure pump, firstly results in an excessively high fuel volume in idle and partial-load operation of the engine, and secondly it results in a considerable wear increase of the high-pressure pump.

According to the invention, by the provision of the inlet valve, it is possible for the pump strokes to be selectively switched to the load-free state due to the fuel supply to the high-pressure pump to be stopped. Thus, in the idle or partial-load operation, for example, it may be provided that the supply of fuel to the high-pressure pump is stopped during every second pump stroke, so that the strokes occur without load. This has the effect of reducing the amount of fuel delivered first and preventing excessive over-delivery. Secondly, the loading of the high pressure pump is significantly reduced, thereby further reducing the more severe wear associated with an increase in pump run frequency.

In one improvement of the invention, it can be provided that the high pressure pump is a multi-piston pump and that the fuel supply to the individual pistons can be selectively stopped by the inlet valve. In this manner, the capacity of the pump in full-load operation in the manner already described above can be increased without the need for an increase in pump volume. In particular, in the idle and / or partial-load operation of the high-pressure pump, it may be provided that the supply of fuel to individual pistons of the pump is stopped to reduce the carrying capacity. Here, in particular, not necessarily the same piston is switched to the rod-free state, but rather it can be provided that the pistons are alternately switched to the load-free state. In this manner, the loading can be evenly distributed across the pistons of the multi-piston pump, and excessive wear of the individual pistons is prevented. Here, in a further refinement of the invention, it may be provided that in the case of a multi-piston high-pressure pump, separate inlet valves are provided for each piston.

In both cases where single-piston pumps are used as high-pressure pumps in common-rail injection systems, and also when multi-piston pumps are used, it is possible to provide, via the provision of inlet valves upstream of the high- It is possible that the delivery capacity varies over a wide range as a function of the operating state of the internal combustion engine.

In a further refinement of the invention, the inlet valve may be provided as a solenoid valve or a piezoelectric valve. Here, in particular, the inlet valve may be provided with a digital inlet valve (DIV). This enables the control of the inlet valve to be integrated into the engine management of modern internal combustion engines.

In a further refinement of the invention, it can be provided here that the inlet valve can be controlled by a control unit (ECU) of the injection system as a function of the operating state of the internal combustion engine. In this way, the delivery capacity of the high-pressure pump can be adjusted in a direct manner by the control unit of the injection system, which makes it possible to adjust the delivery capacity as a function of the engine controller's characteristic map.

In the case of the injection system according to the invention, it is possible to provide an adequate fuel supply to the engine with considerably higher power even in full-load operation by the relatively small piston volumes of the high-pressure pump. Excessive transport of fuel, and related problems associated with fuel heating, can be reduced or eliminated altogether. The energy consumption of the high-pressure pump can be reduced, and thus the efficiency of the internal combustion engine can be increased as a whole.

A further advantage of the present invention is that the delivery accuracy is increased in an operating state having minimum flow velocity delivery by a high pressure pump or having minimum flow velocity consumption by an internal combustion engine. The actual hydraulic delivery capacity per pump stroke at the pump outlet is always slightly off the preset target value by the control unit. The deviation associated with the set transport capacity of the high-pressure pump becomes even greater as the current required transport capacity itself is smaller. Due to the individual pump strokes to be switched to the load-free state, the delivery deviations in the case of minimal delivery can advantageously be significantly reduced, thereby simplifying the pressure regulation in the high-pressure side in the common rail injection system.

According to a further aspect of the present invention there is provided a high pressure pump for a common rail injection system of an internal combustion engine, the common rail injection system having a distributor pipe and one or more injectors. Here, the high-pressure pump delivers fuel for operation of the internal combustion engine to a common rail injection system, in particular to a distributor pipe, which is injected into the combustion chamber of the internal combustion engine 800 by one or more injectors connected to the distributor pipe . In addition, the high-pressure pump has an inlet valve arranged upstream of the high-pressure pump, in particular in the flow plane, by means of which the fuel supply to the high-pressure pump can be selectively stopped for individual delivery cycles of the high-pressure pump.

In a further aspect of the present invention, there is provided a common rail injection system as described above and a vehicle having a high-pressure pump as described above.

The present invention also relates to a method for operating a common rail injection system for an internal combustion engine wherein a high pressure pump carries fuel for operation of the internal combustion engine to a distributor pipe and the fuel is injected by an injector connected to the distributor pipe This method, which is sprayed into the combustion chamber of an internal combustion engine in a manner that is distinguished by the fact that the fuel supply to the high pressure pump is selectively stopped for the individual delivery cycles of the high pressure pump.

As already mentioned above, it is possible by the method according to the invention to carry out an increase in the number of pump strokes of the high-pressure pump without a significant increase in wear of the pump or a decrease in the service life of the pump.

This allows a reliable supply of fuel even to relatively large internal combustion engines by means of relatively small volume high pressure pumps.

In one refinement of this method according to the invention, it is particularly provided here that the fuel supply to the high-pressure pump is stopped as a function of the operating state of the engine. Thus, for example, a high-pressure pump can be operated at a pump stroke frequency corresponding to a plurality of injection frequencies, and in a partially-loaded or idle operating state, some of the pump stroke cycles It may be provided to switch to the load-free state.

In a further refinement of this method according to the invention, the high-pressure pump is a multi-piston pump and the fuel supply to each piston is selectively stopped by the inlet valve. Here, the capacity of the pump in full-load operation can be increased without the need for an increase in pump volume. In particular, in the idle and / or partial-load operation of the high-pressure pump, the fuel supply to the individual pistons of the pump can be provided to be stopped to reduce the carrying capacity. Here, in particular, not necessarily the same piston is switched to the load-free state, but rather the pistons can be alternately switched to the load-free state. In this case, the loading can be evenly distributed across the pistons of the multi-piston pump, preventing excessive wear of the pistons, respectively.

Advantageous improvements of the common rail injection system can be regarded as advantageous examples of high-pressure pumps and automobiles as long as they can be applied to high-pressure pumps and automobiles.

The invention will be described below by way of example with reference to the accompanying drawings based on the preferred exemplary embodiments, and the invention is not limited to these embodiments.

1 is a schematic illustration of a common rail injection system in accordance with the present invention.
Figure 2 shows the pump cycle due to the profile of the camshaft of the high-pressure pump.
Figure 3 shows the delivery curve due to switching to the load-free state of the individual pump strokes of the high-pressure pump.

1 is a schematic illustration of a common rail injection system 100 in accordance with one embodiment of the present invention. Fuel is extracted from the fuel tank 200 through the fuel line 210 by the fuel pump 300. Through the fuel line 310, the fuel is guided to the inlet valve 400 by the fuel pump 300. The inlet valve 400 regulates the supply of fuel to the high-pressure pump 500 via the fuel line 410. Here, the inlet valve 400 may also be an integral component of the high-pressure pump 500. The compressed fuel is delivered to the distributor pipe (rail) 600 through the high pressure line 510 and from the distributor pipe through the high pressure line 610 to the injectors 700. Through the injectors 700, the compressed fuel is injected into the combustion chambers of the internal combustion engine 800. The distributor pipe 600 is connected to the fuel tank through a fuel return line 620. Through the fuel recovery line 620, excess fuel is recovered from the distributor pipe 600 to the fuel tank. Here, the injector system 100 is controlled by a control unit 900 connected at least to the injectors 700 and the inlet valve 400 in a signal-transmission manner via control lines 910. [ According to the present invention, it is hereby provided that the high-pressure pump operates at a pump stroke frequency corresponding to a multiple of the injection frequency of the fuel injected into the combustion chambers of the internal combustion engine 900 by the injectors 700. Whereby the high-pressure pump 500 delivers the fuel to the appropriate amount of distributor pipe 600, even during the full-load operation of the internal combustion engine 900. The fuel supply to the high-pressure pump 500 may be selectively stopped by the inlet valve 400 for individual pump strokes of the high-pressure pump 500 to prevent large excess delivery of fuel to the distributor pipe 600 . In this manner, the pump strokes are switched to a load-free state and do not carry fuel to the distributor pipe 600. Excess recovery of fuel through the fuel recovery line 620 can be avoided in this manner. It is also achieved in this way that the excessive load of the high pressure pump 500 and the more severe wear of the high pressure pump 500, which may be associated with an excessive load of such a high pressure pump, are prevented. The inlet valve 400 may be, for example, in the form of a digitally actuatable solenoid or piezo valve controlled by the control device 900 as a function of the injection frequency and / or the fuel pressure of the distributor pipe 600 in this case (In other words, it can be in DIV format). In this manner, the control unit is provided with additional characteristic curves in which optimized control of the internal combustion engine can be considered.

Figure 2 shows pump cycles due to the profiles of the camshafts of the high pressure pump. If the two-cam cam shaft 530 is used to drive the pump piston of the high-pressure pump, a pump cycle curve 535 is obtained. Here, the stroke of the pump piston depends on the distance between the top dead center and the bottom dead center of the camshaft. Here, the cycle from the top dead center to the bottom dead center and back to the top dead center corresponds to one pump cycle. Due to the fact that the number of cams on the four cam cam shaft 540 is twice the number of cams on the two cam cam shaft 530, the number of pump cycles in the pump cycle curve 545 is also doubled. This results in a doubling of the carrying capacity for the unchanging pump volume of the high-pressure pump.

Figure 3 shows the delivery curves due to the switching of individual pump strokes of the high pressure pump to the load-free state. Here, the delivery curve 550 shows the delivery capacity of a high-pressure pump having a two-cam camshaft as indicated by 530 in FIG. The delivery curve 570 shows the delivery capacity of the pump with the same pump volume, although it has a 4-cam cam shaft as indicated by 540 in Fig. The carrying capacity of the four-cam camshaft shown in the delivery curve 570 is very high for the partial-load or idling operation of the internal combustion engine. Thus, in accordance with the present invention, in an alternative manner, the pump cycles of the high pressure pump are switched to a load-free state, i.e. the fuel supply to the high pressure pump is stopped for selective pump strokes. The delivery curve 560 is designed such that only the second pump stroke carries fuel and the fuel supply to the high pressure pump for the other pump strokes is stopped by the inlet valve provided in accordance with the present invention. Indicates the carrying capacity of the high-pressure pump. In this case the carrying capacity is between full transportation by means of a 4-cam high pressure pump of the same volume as that of the same volume of 2-cam high pressure pump, i. This is obvious. In this way, even if relatively small-volume high-pressure pumps are used, it becomes possible to provide a reliable supply of fuel to a relatively large internal combustion engine, whereby the efficiency of the internal combustion engine can be increased overall.

100: Common rail injection system
200: Fuel tank
210: fuel line
300: Fuel pump
310: fuel line
400: inlet valve
410: fuel line
500: High pressure pump
510: High pressure fuel line
530: 2-cam camshaft
535: Pump cycle curve
540: 4-cam cam shaft
545: Pump cycle curve
550: Carrying curve
560: Carrying curve
570: Carrying curve
600: Dispenser pipe (rail)
610: High pressure fuel line
620: Fuel recovery line
700: Injector
800: Internal combustion engine
900: control unit (ECU)
910: control line

Claims

A common rail injection system (100) for an internal combustion engine (800) having a high pressure pump (500), a distributor pipe (600) and at least one injector (700), wherein the high pressure pump (500) (800) in which fuel can be injected into the combustion chamber of the internal combustion engine (800) by one or more injectors (700) that carry fuel to the distributor pipe (600) In the common rail injection system 100,
The injection system 100 has an inlet valve 400 arranged upstream of the high pressure pump 500 in the flow plane so that the fuel supply to the high pressure pump 500 is controlled by the inlet valve, Can be selectively stopped for cycles,
The high pressure pump 500 is a multi-piston pump and the fuel supply to the individual pistons can be selectively stopped by the inlet valve 400,
Characterized in that the pistons are alternately switched to the load-free state, rather than the same piston being always switched to a load-free state, so that the loading is evenly distributed across the pistons of the multi-piston pump ,
Common rail injection system.

delete

The method according to claim 1,
Characterized in that the inlet valve (400) is a solenoid valve or a piezoelectric valve.
Common rail injection system.

The method according to claim 1 or 3,
Characterized in that the inlet valve (400) is controllable by the control unit (900) of the common rail injection system as a function of the operating state of the internal combustion engine (800)
Common rail injection system.

The method according to claim 1 or 3,
Wherein the pump stroke frequency of the high-pressure pump (500) is a multiple of the injection frequency.
Common rail injection system.

A high pressure pump (500) for a common rail injection system of an internal combustion engine (800) that delivers fuel for operation of an internal combustion engine (800) to a common rail injection system,
The high pressure pump has an inlet valve 400 arranged upstream of the high pressure pump 500 in the flow plane so that the supply of fuel to the high pressure pump 500 by the inlet valve is selective for the individual delivery cycles of the high pressure pump 500 Lt; / RTI >
The high pressure pump 500 is a multi-piston pump and the fuel supply to the individual pistons can be selectively stopped by the inlet valve 400,
Characterized in that the pistons are alternately switched to the load-free state, rather than the same piston being always switched to the load-free state, so that the loading is evenly distributed across the pistons of the multi-
High pressure pump for common rail injection system of internal combustion engine.

A method for operating a common rail injection system for an internal combustion engine, in which a high-pressure pump delivers fuel for operation of an internal combustion engine to a distributor pipe, and the fuel is atomized by injection into a combustion chamber of an internal combustion engine by an injector connected to the distributor pipe In this case,
The fuel supply to the high-pressure pump is selectively stopped for individual delivery cycles of the high-pressure pump,
The high pressure pump 500 is a multi-piston pump and the fuel supply to the individual pistons can be selectively stopped by the inlet valve 400,
Characterized in that the pistons are alternately switched to the load-free state, rather than the same piston being always switched to the load-free state, so that the loading is evenly distributed across the pistons of the multi-
A method of operating a common rail injection system for an internal combustion engine.

8. The method of claim 7,
Characterized in that the fuel supply to the high-pressure pump is stopped as a function of the operating state of the engine.
A method of operating a common rail injection system for an internal combustion engine.

delete

9. The method according to claim 7 or 8,
Characterized in that the high-pressure pump is operated such that the pump stroke frequency is a multiple of the injection frequency.
A method of operating a common rail injection system for an internal combustion engine.

A vehicle characterized by comprising a common rail injection system according to any one of claims 1 to 3.