KR20140112419A - Method for controlling a fuel injection system - Google Patents

Abstract

The present invention relates to a method of controlling a fuel injection system of an internal combustion engine of an automobile having a start-stop function, the fuel injection system including a high-pressure pump (10) supplied with fuel from a pre- When the pressure in the high-pressure reservoir 40 in which the pressure from the high-pressure pump 10 is pressurized is reduced to a predetermined minimum pressure or less during the stop-step, the motor shaft of the internal combustion engine is rotated once or more, The cam 30 capable of driving the high-pressure pump 10, which operates in conjunction with the high-pressure pump 10, is operated.

Description

METHOD FOR CONTROLLING A FUEL INJECTION SYSTEM BACKGROUND OF THE INVENTION [0001]

The present invention relates to a method of controlling a fuel injection system of an internal combustion engine having a start-stop function, and the fuel injection system includes a high-pressure pump that receives fuel from a pre-feed pump.

Conventionally, an existing internal combustion engine having a so-called start-stop function is known. These internal combustion engines are automatically stopped through injection suppression to reduce consumption or save fuel at the time of stoppage. For re-operation of the internal combustion engine, for example, a new start request is generated through the user of the internal combustion engine, whereby the starter installed in the internal combustion engine is activated and a new start process is performed through the start of the starter.

In such an internal combustion engine, the re-operation after the stop step is generally subject to the generated start request and keeps the necessary start-up time as short as possible to re-start to avoid sacrificing convenience. Moreover, each re-start can result in undesired and subjectively unpleasantly accepted noise, which can occur during operation of the pre-feed pump of the internal combustion engine, which applies a load to the power supply system and in particular for restarting .

In order to normally start the internal combustion engine of the hybrid vehicle, it is necessary to reserve the torque of the electric device. This reduces the moment available for subsequent electrical running, which necessitates a larger dimension of the electrical machine. In order to avoid this, a so-called direct start is preferred, in which the injection or ignition is performed when the motor is stopped or operating, in a hybrid vehicle.

The prerequisite for direct start is that the pressure of the high pressure pump system is not reduced below the minimum value. For example, due to leakage in the high pressure pump system through the pressure control valve or the exhaust valve of the high pressure pump, sufficient pressure is available only for a limited time after the stop, and if the pressure is reduced below the minimum pressure, direct start is no longer possible .

Alternatively, it is attempted to develop the common-rail-system in a particularly more closed configuration, so that the pressure in the high-pressure pump can be maintained without the fuel being discharged in the low-pressure circulation. This, however, makes the requirements for the sealing of the high pressure pump considerably more difficult, resulting in high costs.

Likewise, additional devices for pressure formation, such as controllable or intelligent reservoirs, heating elements, additional pumps, etc., may be considered. These additional devices are also associated with high cost.

It is an object of the present invention to provide a method and an apparatus for enabling re-start after a stop step to a shorter starter run time in an internal combustion engine having a start-stop function, without increasing manufacturing cost.

This object is achieved by a method of controlling a fuel injection system of an internal combustion engine having the features of claim 1.

The present invention makes it possible to shorten the re-start time after the stop step in the internal combustion engine having the start-stop function.

Particularly, according to the present invention, the high pressure start is simplified as compared with the conventional solutions. It is understood here that the high pressure start (rail pressure> 20 bar, typically injection in the compression stroke) forms a preferential pressure in the high pressure system until it exceeds the jet opening threshold. Subsequently, injection and start are carried out. Particularly, according to the present invention, iterative start can be carried out with a direct start, suggesting a specific embodiment of high pressure start. At such start, injection and ignition are performed on a stopped or operating motor.

Overall, according to the present invention, the start time is shortened and operation by the starter or electric motor (especially in the case of a hybrid vehicle) is completely omitted, or in all cases can be achieved with significantly reduced torque.

According to the present invention, the pressure build-up is provided to the high-pressure system even when the motor is stopped by a simple method, so that a direct start is possible at any time. The invention can also be used in gasoline systems or diesel systems.

According to the present invention there is provided a method having the features of independent claim 1. Preferred embodiments are in accordance with the dependent claims and the description which follows.

According to the present invention, it is possible in a simple manner to maintain the pressure in the high-pressure system of the internal combustion engine higher than the system pressure required for direct start-up. According to the invention, this is feasible without the more demanding requirements for the hermeticity of the high-pressure pump, or without additional devices for pressure forming. In the present invention, a motor, which is capable of operating the high-pressure pump by rotating the internal combustion engine sporadically, i. E. During the braking process or at the time of the occurrence of the reduced load, once or several times during the stopping step, The high pressure pump can be operated by the cam acting with the shaft.

Preferably, the one or more rotations are effected by operation of a clutch capable of engaging the drive shaft of the vehicle with the motor shaft of the vehicle. This makes it possible to rotate the motor shaft for the operation of the high-pressure pump while the vehicle is running, for example by using an existing automotive clutch in a simple manner.

Likewise, one or more rotations of the motor shaft through the clutch connecting the flywheel to the motor shaft may be considered. In this way, it is also possible to perform the operation of the high-pressure pump according to the present invention during the stop-step in the stopped automobile in the motor in which the flywheel is formed.

Particularly, it is preferable to use the method according to the present invention in controlling the internal combustion engine by hybrid drive. In such a hybrid drive including an internal combustion engine and an electric motor, it is possible to make the electric motor smaller in size than the existing system.

A control unit of a computer unit according to the invention, for example an automobile, is designed to perform the method according to the invention, in particular in a programmed manner.

Implementing the method in software is particularly desirable because it saves money and is especially true where the control device used is also used for other tasks and is therefore already provided. Data media suitable for preparing a computer program include a diskette, a hard disk, a flash memory, an EEPROM, a CD-ROM, a DVD, and the like. It is also possible to download a program through a computer net (Internet, intranet, etc.).

Additional advantages and embodiments of the invention are set forth in the description of the invention and the accompanying drawings.

It is understood that the above-described features and features to be described below are not to be used for the respective combinations alone, but can be used in other combinations or independent configurations without departing from the scope of the present invention.

BRIEF DESCRIPTION OF THE DRAWINGS The invention is illustrated schematically in the drawings as an embodiment and is described in detail below with reference to the figures.

1 is a schematic view of a fuel injection system of an internal combustion engine having a high-pressure pump, in which the method of the present invention can be used,
2 schematically shows a power transmission of an internal combustion engine in which the method of the present invention can be used,
Figure 3 is a schematic representation of various system parameters for illustrating a preferred embodiment of the method according to the present invention.

Fig. 1 schematically shows a fuel injection system 1 of an internal combustion engine 42 having a start-stop function. Which comprises a fuel tank 2 from which the prefeed pump 3 pumps the fuel high pressure pump 10 driven by the cam 30 through the conduit 4 at a corresponding pre-supply pressure. The high-pressure pump (10) is provided with both control valves (20) on the low-pressure side. The amount of feed of the high-pressure pump 10 is set through the both control valves 20. [ The cam 30 is driven by the internal combustion engine 42 and may be driven by, for example, an installed motor shaft and may also be part of such motor shaft. Such a motor shaft is described in more detail in Fig. 2 and is designated by the reference numeral "64 ".

The high-pressure pump 10 preferably has a transfer space with a check valve installed on the input side. This seals the fuel at a very high pressure and conveys it through the conduit 5 to the high pressure reservoir 40 where the fuel is stored at a very high pressure, also referred to as a "distributor pipe" or "rail ". A plurality of injection valves or injectors 41 are connected to inject fuel into a combustion space provided corresponding to an internal combustion engine 42 not shown in detail. The internal combustion engine 42 serves to drive an automobile, for example.

The actual-fuel pressure of the high-pressure reservoir 40 is detected by the pressure sensor 43. The pressure sensor 43 transmits its signal to the control and regulating device 46 which is connected to the temperature sensor 45 at the input side and to a rotational speed sensor 44). The control and regulating device 46 is connected on the output side with the pre-feed pump 3 and both control valves 20.

The control and regulating device 46 implements the start-stop function of the internal combustion engine 42 and is used to control the internal combustion engine 42 is stopped. In the stop-step of the internal combustion engine 42 leading to the operation stop, the pre-feed pump 3 drives the internal combustion engine 42 in accordance with the driving parameters of the internal combustion engine 42 in order to enable the accelerated start of the internal combustion engine 42 in the following start- As shown in FIG.

2 shows the power transmission from the internal combustion engine (also denoted at 42) to the drive shaft 50. In Fig. As is known, the internal combustion engine drives the motor shaft 44, which can be coupled to or disconnected from the gear input shaft 47 of the gear 48. The drive shaft 50 of the vehicle is driven through the gear 48. [

In a vehicle having a start-stop function, the internal combustion engine can also be stopped during the operation of the vehicle, and also can reach the stop-step. Here, the motor shaft 44 does not rotate. The disengagement of the clutch 46 also separates the motor shaft 44 and the gear input shaft 47 from each other. Accordingly, only when the vehicle is moving, the gear input shaft 47 and the drive shaft 50 are rotated. According to a preferred embodiment of the method of the present invention, when there is a stop-step of the internal combustion engine 42 at the same time while the vehicle is moving, the clutch 46 is operated to cause the rotation of the motor shaft 44 They are combined for a short time. The motor shaft 64 is formed with a cam 30 which has already been described with reference to Fig. 1 but which is not shown. Overall, the rotation of the cam 30 is achieved through the rotation of the motor shaft 64 caused by the movement of the vehicle through which the high-pressure pump 40 is operated.

In Fig. 3, various parameters measured or generated in connection with the method of the present invention are shown with respect to time. This is shown schematically. The abscissa indicates the time, and the ordinate optionally indicates the rail pressure p, the vehicle speed v, or the motor speed n.

The number of revolutions of the motor provided in the internal combustion engine is shown with respect to time and is indicated by reference numeral 300. [ As is verified, the internal combustion engine is driven until the time t ₀ , and accordingly, the motor rotational speed 300 has a positive value. The rail pressure indicated by reference numeral 310 is constant during this time. The speed of the vehicle (indicated by "320") also has a positive value.

When the stop-procedure is introduced at the time point t ₀ , the motor rotational speed 300 decreases to zero in a short time. Correspondingly, the vehicle speed 320 and the rail pressure 310 are also reduced. At time t ₁ , the rail pressure has a pressure value (p ₀ ) denoted by 312. This pressure value represents the minimum pressure that must be set so that it can be used in the high pressure reservoir 40 (see Figure 1) to enable direct start of the internal combustion engine. According to the present invention, at the time point t ₁ , the drive shaft is engaged with the motor shaft by engagement of the clutch shown for example with reference to FIG. 2, whereby the motor shaft is rotated several times. In the illustrated example, the rotation of this internal combustion engine takes place between a time point t ₁ and an additional time point t ₂ . Motor speed 300 is also greater than zero during this time. Thus, it is confirmed that the rail pressure 310 again exceeds the threshold value 312. The internal combustion engine 42 start-of-reached, at the time (t ₃₎ that allows the request may be directly start is performed without time delay. As is apparent without further explanation, the rail pressure 310 as well as the motor speed 300 is thereby raised after the start-request at time t ₃ . After a minimum delay that the driver can not detect, the car is accelerated at time t ₄ .

Claims (6)

A method for controlling a fuel injection system of an internal combustion engine of an automobile having a start-stop function, the fuel injection system comprising a high-pressure pump (10) supplied with fuel from a pre-feed pump (3)
When the pressure in the high-pressure reservoir 40 in which the pressure from the high-pressure pump 10 is pressurized is reduced to a predetermined minimum pressure or less during the stop-step, the motor shaft of the internal combustion engine is rotated once or more, Characterized in that the cam (30) acting in conjunction with the fuel injection system of the internal combustion engine of the vehicle having the start-stop function is activated and the high-pressure pump (10) can be driven by the cam . The motor vehicle of claim 1, wherein said one or more rotations are accomplished by operation of a clutch (66) that allows the drive shaft of the vehicle to engage the motor shaft. A method for controlling a fuel injection system of an engine. 2. A method according to claim 1, characterized in that said one or more rotations are effected by the actuation of a clutch allowing the flywheel of the vehicle to engage with the motor shaft. How to control the system. A method for controlling an internal combustion engine of a hybrid-drive unit by the method according to any one of claims 1 to 3. A computer unit configured to perform the method according to any one of claims 1 to 3. A computer program having program code means for causing a computer unit to perform the method according to any one of claims 1 to 3 when executed on a computer unit.

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