KR20140035915A - Method for operating an internal combustion engine - Google Patents

Abstract

A method and apparatus for operating an internal combustion engine having an accumulator injection device are provided. In this method, fuel is introduced into the rail by a high pressure pump, and the high pressure pump is driven by a metering supply unit, for which the metering supply unit adjusts an adjustment value 58 which is determined based on the pilot controls 22, 24. Receiving, open circuit control of the metering supply unit is executed.

Description

How an internal combustion engine works {METHOD FOR OPERATING AN INTERNAL COMBUSTION ENGINE}

The present invention relates to a method of operating an internal combustion engine having an accumulator injection device and an apparatus for carrying out the method.

The injection system is used in an internal combustion engine in which operation of an accumulator injection device, also referred to as a common rail injection device, is carried out, in which a high pressure pump provides fuel at high pressure levels. The pressurized fuel is present in a pressure accumulator that is constantly pressurized during operation.

In this way, the pressure generation can be completely separated from the injection process, and the injection device is only controlled by the characteristic map, wherein the injection timing and injection amount are controlled by the electronic engine controller. Fuel present in the pressure accumulator or rail is injected into the combustion chamber through an injection valve. Therefore, in order to maintain pressure in the rails, fuel is supplied to the rails via a high pressure pump driven by the metering supply unit MPROP continuously or at regular intervals. To this end, the metering supply unit obtains an adjustment from the output of the closed-loop control of the pressure in the pressure accumulator, where the closed-loop control is again signaled by a pressure sensor which measures the pressure in the rail.

The pressure in the rail is thereby monitored or controlled using a pressure sensor or rail pressure sensor to always maintain the desired pressure in the rail. Pressure control valves are also provided in most injection systems to allow closed loop control of pressure in the rail.

From document DE 10 2010 0298 40 A1 a method of operation of an internal combustion engine is known, in which an undesired pressure deviation can be prevented. Changes in driver requirements are then identified. As a result of the driver requirement change, a pressure correction value is detected, and an adjustment signal supplied to the control section is changed in accordance with the pressure correction value.

In a common rail system with a rail without a controller and a pressure control valve in the metering feed part (MPROP) for a high pressure pump, the rail pressure cannot be set sufficiently accurately with recently used software if the rail pressure sensor is damaged. The system is also referred to as a 1-controller system. The two-controller system includes one controller and additionally a pressure control valve in the metered feed part. As a result, the injection amount, which depends in particular on the rail pressure, no longer corresponds exactly to the driver's requirements, since the rail pressure is not measured without the rail pressure sensor.

Thus, up to now it has been provided to stop the engine in injection systems without a pressure control valve in the event of a failure of the rail pressure sensor. The vehicle is simply no longer able to operate due to a failure of the rail pressure sensor. However, this response is not acceptable to many vehicle manufacturers. However, if engine stoppages are omitted, considerably worse driving behavior must be taken into account.

In this context, a method according to claim 1 and an apparatus having the features of claim 9 are provided. Embodiments are provided in the dependent claims and in the specification.

The above-described method operates the internal combustion engine without the rail pressure sensor because the open circuit control of the metering supply unit and thus the open circuit control of the amount of fuel introduced into the rail are executed based on the adjustment value detected based on the pilot control unit. Makes it possible.

In an embodiment starting from closed loop controlled operation using a rail pressure sensor in the method of operating an internal combustion engine provided, one or more emergency driving functions can be ensured in the event of a failure of the rail pressure sensor. The easy adaptation of the software functions and the correction function to be learned allow for virtually improved rail pressure control without a rail pressure sensor, thereby improving driving behavior.

This translates from closed loop-controlled operation to open-loop-controlled operation in the event of a failure of the rail pressure sensor. This means that the amount of fuel supplied into the rail through the metering supply unit is no longer closed loop controlled based on the signal of the rail pressure sensor but rather open circuit controlled. To this end, an adjustment value is determined based on the pilot control and, in some cases, determined in consideration of the adaptive metering curve (AMC) as a correction function. At idle, additional pilot controls may be considered further. The idle controller can then transmit a signal that is used to openly control the metering supply unit.

Typically the AMC is learned during trouble-free operation in the metering supply unit and is therefore typically continuously adjusted. The AMC takes into account the volumetric flow rate deviation between the normal system demand (normal physical pilot control) and the adjustment of the metering supply unit during closed loop control operation.

Other advantages and embodiments of the present invention are provided from the specification and the accompanying drawings.

The aforementioned features and features to be described further below may be used alone or in any other combination as well as in the combinations provided, without departing from the scope of the present invention.

1 is a flow diagram for performing the described method.
2 shows an embodiment of the described apparatus.

The invention is schematically illustrated in the drawings by embodiments and described in detail in connection with the drawings as follows.

In Figure 1 an embodiment of the provided method is shown by a flow diagram. The flow is then divided into four parts: part A 10, part B 12, part C 14, and part D 16. This figure clarifies the adjustment of the detection value for the metering supply unit MPROP for the case where the failure of the rail pressure sensor should be switched from closed loop controlled operation to open loop controlled operation.

Part A 10 is shown a switch 20 capable of converting between a normal physical pilot control 22 and a minimum physical pilot control 24.

In the part B 12, correction using the learning value of the adaptive metering supply curve (AMC) 30 is made as long as said metering supply curve exists.

In part C 14 the pump tolerance 40 may be taken into account depending on whether the AMC 30 could already be learned, in particular.

The part D 16 is provided with a switch 50 to which the additional pilot control unit 52 can be connected when the internal combustion engine is idling 54. The output 56 is provided with an adjustment variable 58 for controlling the metering supply unit in an open loop.

In the above case without the rail pressure sensor, it was recognized that the rail pressure control is executed to allow continuous running of the vehicle without the pressure sensor.

However, the following two problems are provided.

1. The driving behavior is very dependent on the system tolerance, that is, the tolerance of the control amount and the leakage amount of the injector, the tolerance of the injection amount, the tolerance of the pump characteristic curve and the control device.

2. Particular attention should be paid to the inadequate rail pressure control for idling, as it involves the idling controller. Although the rail pressure remains the same as the control device delivers, when the rail pressure in the pressure accumulator or rail increases or decreases, the injection volume increases or decreases, so that the metering supply unit (MPROP) for the high pressure pump is Despite the integrated behavior of open-loop control, the rail pressure finds a stable point in normal operation. In idling, the idling controller reacts inversely to the above injection amount variation.

The first problem is reacted as follows.

1. In part A 10, a physical pilot control 22 or 24 is used.

2. The minimum demand of the system is detected so that too little is introduced rather than too much into the rail. Just as the physical pilot control detects the maximum demand of the system from the normal demand of the system, the minimum demand of the system can be detected. This is done when stoppage is required rather than too much injection volume. This is done in part A 10.

Normal pilot control means that the volumetric flow rate demand that the high pressure pump must deliver to the rail is computed. The injection amount and the rotation speed are known at this time. This allows the volumetric flow rate to be calculated. From the injection amount the control amount, ie the amount for operation, ie the amounts for opening and closing of the injector can be calculated. Injector leaks are also measurable for normal systems and stored in the form of characteristic maps at the control unit.

Injection amount, control amount, and injector leak are known and have a certain tolerance. These tolerances are taken into account in the calculation to computationally detect the volume flow demand of the system with the minimum demand as the minimum pilot control.

Basically, the pilot control again depends on the amount of injection that depends on the engine speed, so that it is possible to anticipate how much fuel should flow into the rails.

3. Use calibration with AMC 30 to reduce the effects of component tolerances. This requires the recognition of AMC learning tolerances. This is done in part B 12.

4. The demand of the pump is reduced from the pump characteristic curve or the known tolerance of the pump tolerance 40 so that it is conveyed too little on the rail rather than again too much. This is done in part C 14.

In connection with the second problem, additional pilot controls 52 can be added depending on the injection volume at idle 54. If the idle controller reduces the injection volume below the normal idle demand, this means that the rail pressure is higher than expected and the pump supplies too much. If the injection amount is increased and vice versa, the additional pilot control must reduce the supply amount of the pump. This is done in part D 16.

At the output 56 one value is provided which is used directly as an adjustment value 58 for the metering supply unit. Parts A 10 through D 16 can be irradiated, analyzed and used independently of one another. The data of the first switch 20 and the pump tolerance 40 can be designed in consideration of the manufacturer's safety regulations.

In an embodiment in the provided method, when damage to the rail pressure sensor is identified, a switchover is made from a closed loop controlled manner to an open loop controlled manner. If damaged, the adjustment value of the metering supply unit must jump from the controller output to the output 56 shown in FIG. 1. To prevent a jump in the rail pressure, the ramp start value can be initialized so that the adjustment value of the metering supply unit does not form a jump. Thus the starting value of the ramp may correspond to the last controller output value (without P-ratio) minus the value 58 at the output 56. The ramp output is added to the output 56 and then drops to zero step by step. If the rail pressure sensor is identified as damaged, the P-ratio is not used to initialize the lamp, since the pressure controller deviation is sometimes not valid.

In FIG. 2, a pressure accumulator or rail 80 of an internal combustion engine in which a fuel under pressure is present is shown, the fuel being a first injection valve 82, a second injection valve 84, and a third injection valve. 86 and fourth injection valve 88 may be injected into a combustion chamber, such as a cylinder of an internal combustion engine, for example. In order to simplify the illustration, only the third injection valve 86 is shown in detail in FIG. 2.

Also provided with rail 80 is a rail pressure sensor 90 that measures pressure at rail 80 and outputs a signal 92 representative of the pressure. This signal 92 is different from the second signal 94 of the accelerator pedal 96, the third signal 98 of the crankshaft 100, the fourth signal 102 of the camshaft 104, and other sensors. And one or more other signals 106 to the control device 120. The control device 120 controls the actuator provided through the first output unit 122, controls the injection valves 82 to 88 through the second output unit 124, and controls the third output unit 126. By way of example, the metering supply unit 130 of the high pressure pump 132 that supplies the fuel 146 to the rail 80 through the line 134 is controlled.

The illustration also shows a fuel filter 140, an inspection valve 142, and a tank 144 in which the fuel 146 is present. Also provided in the tank 144 is a pre-supplied electric pump 150 and a pre-filter 152.

Thereby the rail pressure sensor 90 in error-free operation supplies a signal 92 which is used to control the metering supply unit 130 in a closed loop and thereby to control the fuel flowing out of the high pressure pump 132 to the rail in a closed loop. . If the rail pressure sensor 90 fails, the control device 120 calculates one value which is used as an adjustment value for openly controlling the metering supply unit, as described in the relationship with FIG. 1.

Claims (9)

A method of operating an internal combustion engine having an accumulator injection device, in which fuel is introduced into the rail 80 by a high pressure pump 132, where the high pressure pump 132 is driven by the metering supply unit 130. To this end, the metering supply unit receives the adjustment value 58 determined based on the pilot controllers 22 and 24 to control the open circuit of the metering supply unit 130 and thereby the open circuit control of the rail pressure. Executed, how the internal combustion engine works. 2. The adjustment value 58 for the metering supply unit 130 is first determined on the basis of a closed loop control, ie based on the signal of the rail pressure sensor 90 monitoring the pressure on the rail 80. And switching from the closed loop control of the metering supply unit 130 to the open circuit control of the metering supply unit 130 in the event of a failure of the rail pressure sensor 90. 3. The lamp according to claim 2, wherein when switching from the closed loop control of the metering supply unit 130 to the open circuit control of the metering supply unit 130, the ramp so that the adjustment value 58 of the metering supply unit 130 does not form a jump. The method of operation of the internal combustion engine, in which the starting value is initialized. Method according to any of the preceding claims, wherein the adaptive measurement curve (30) is taken into account in the determination of the adjustment value (58). 5. The method according to claim 2, wherein the adaptive measuring curve is learned with a rail pressure sensor during operation. 6. The method according to any of the preceding claims, wherein an additional pilot control (52) is considered at idle (54) in determining the adjustment value (58). 7. A method according to claim 6, wherein the idle controller outputs a signal considered to determine the adjustment value (58). 8. A method according to any one of the preceding claims, wherein the pump tolerance (40) is taken into account when determining the adjustment value (58). A device for operation of an internal combustion engine with an accumulator injection device, in which a high pressure pump 132 is provided for introducing fuel 146 into the rail 80 and based on an adjustment value 58. A metering supply unit 130 is provided which is used to drive 132, wherein the device is configured of an internal combustion engine, in which the adjustment value 58 is formed in a way that can be determined based on the pilot controls 22, 24. Working device.

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