Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02D—CONTROLLING COMBUSTION ENGINES
  • F02D41/00—Electrical control of supply of combustible mixture or its constituents
  • F02D41/30—Controlling fuel injection
  • F02D41/38—Controlling fuel injection of the high pressure type
  • F02D41/3809—Common rail control systems
  • F02D41/3836—Controlling the fuel pressure
  • F02D41/3863—Controlling the fuel pressure by controlling the flow out of the common rail, e.g. using pressure relief valves
  • F02D41/3872—Controlling the fuel pressure by controlling the flow out of the common rail, e.g. using pressure relief valves characterised by leakage flow in injectors
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02B—INTERNAL-COMBUSTION PISTON ENGINES; COMBUSTION ENGINES IN GENERAL
  • F02B37/00—Engines characterised by provision of pumps driven at least for part of the time by exhaust
  • F02B37/12—Control of the pumps
  • F02B37/16—Control of the pumps by bypassing charging air
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02D—CONTROLLING COMBUSTION ENGINES
  • F02D41/00—Electrical control of supply of combustible mixture or its constituents
  • F02D41/02—Circuit arrangements for generating control signals
  • F02D41/14—Introducing closed-loop corrections
  • F02D41/1401—Introducing closed-loop corrections characterised by the control or regulation method
  • F02D2041/141—Introducing closed-loop corrections characterised by the control or regulation method using a feed-forward control element
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02D—CONTROLLING COMBUSTION ENGINES
  • F02D2200/00—Input parameters for engine control
  • F02D2200/02—Input parameters for engine control the parameters being related to the engine
  • F02D2200/06—Fuel or fuel supply system parameters
  • F02D2200/0602—Fuel pressure
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02D—CONTROLLING COMBUSTION ENGINES
  • F02D2200/00—Input parameters for engine control
  • F02D2200/60—Input parameters for engine control said parameters being related to the driver demands or status
  • F02D2200/602—Pedal position
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02D—CONTROLLING COMBUSTION ENGINES
  • F02D2250/00—Engine control related to specific problems or objectives
  • F02D2250/04—Fuel pressure pulsation in common rails
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F02—COMBUSTION ENGINES; HOT-GAS OR COMBUSTION-PRODUCT ENGINE PLANTS
  • F02M—SUPPLYING COMBUSTION ENGINES IN GENERAL WITH COMBUSTIBLE MIXTURES OR CONSTITUENTS THEREOF
  • F02M59/00—Pumps specially adapted for fuel-injection and not provided for in groups F02M39/00 -F02M57/00, e.g. rotary cylinder-block type of pumps
  • F02M59/20—Varying fuel delivery in quantity or timing
  • F02M59/36—Varying fuel delivery in quantity or timing by variably-timed valves controlling fuel passages to pumping elements or overflow passages
  • F02M59/366—Valves being actuated electrically

Definitions

• the invention relates to a method for operating an internal combustion engine according to the preamble of claim 1. It is known that to operate an internal combustion engine pressures must be regulated. Examples are the regulation of a fuel pressure in a high-pressure accumulator of the internal combustion engine or the boost pressure in an intake pipe after a compressor and before entering the
• High pressure pump can lead to unwanted pressure deviations.
• the problem underlying the invention is solved by a method according to claim 1.
• Advantageous developments are specified in subclaims. Features which are important for the invention can also be found in the following description and in the drawings, wherein the features, both alone and in different combinations, can be important for the invention, without being explicitly referred to again.
• the method advantageously generates a pressure correction value from the driver's request. A control signal will depend on the
• Pressure correction value changed From the driver's request can be quickly and easily closed to changes in the operating conditions of the engine and appropriate measures can be taken to prevent unwanted pressure variations.
• Pressure correction value used to change the control signal. Any delays caused by hydraulic processes in the high-pressure pump are thus advantageously bypassed and an undesired pressure deviation can be avoided. Accordingly, a load on the components of
• an accelerator pedal gradient is used to determine a change in the driver's request. From the
• the accelerator gradient is compared with a threshold value. If the threshold is exceeded, the accelerator gradient is compared with a threshold value. If the threshold is exceeded, the accelerator gradient is compared with a threshold value. If the threshold is exceeded, the accelerator gradient is compared with a threshold value. If the threshold is exceeded, the accelerator gradient is compared with a threshold value. If the threshold is exceeded, the accelerator gradient is compared with a threshold value. If the threshold is exceeded, the accelerator gradient is compared with a threshold value. If the threshold is exceeded, the
• Pressure correction value activated at a first time, wherein the first time corresponds to a threshold exceeded by the driver's request.
• Pressure correction value is activated only at a second time, which is after the first time. By this second time can more
• the second time and a third time at which the pressure correction value is deactivated depend on a rotational speed of the internal combustion engine. Since it is possible to deduce the characteristic of the expected deviation of the pressure from the rotational speed of the internal combustion engine, the rotational speed is the starting point for the determination of the times. Thus, the unwanted pressure deviation in direct dependence on the operating state, represented by the
• Pressure correction value would result in undershot or overshoot of the pressure, which can be avoided by the ramp function.
• a further activation after activation of the pressure correction value by a debounce time is not performed.
• a further activation after activation of the pressure correction value by a debounce time is not performed.
• Pressure correction value linked and applied to a controller The controller generates the actuating signal.
• the method accordingly advantageously intervenes to a limited extent in an existing controller structure. This can be avoided that an application of the customer must be changed because the pressure correction value is fed directly to the controller. Likewise, a must Feedforward control, for example in the form of a Juckeldämpfers, not be adjusted.
• Figure 1 is a simplified diagram of a fuel injection system of a
• Figure 2 is a schematic block diagram for determining a
• FIG. 3 shows a schematic block diagram of a controller structure for
• Figure 4 is a schematic diagram in two sections, each with deactivated and activated pressure correction value.
• FIG. 1 shows a fuel injection system 1 of an internal combustion engine in a much simplified representation.
• a fuel tank 9 is connected via a suction line 4, a prefeed pump 5 and a low-pressure line 7 with a (not explained in detail) high-pressure pump 3.
• a high-pressure accumulator 13 (“common rail") is connected via a high-pressure line 1 1.
• a metering unit 14 - hereinafter referred to as ZME - with an actuator 15 is hydraulically in the course of the low pressure line 7 between the prefeed pump 5 and the high pressure pump 3 is arranged.
• Other elements, such as valves of the high-pressure pump 3, are not shown in the figure 1.
• the ZME 14 may be formed as a unit with the high-pressure pump 3.
• an intake valve of the high pressure pump 3 may be forcibly opened by the ZME 14.
• the prefeed pump 5 promotes fuel from the fuel tank 9 into the low pressure line 7 and the
• High pressure pump 3 delivers the fuel into the high pressure accumulator 13.
• the ZME 14 determines the high pressure pump 3 supplied fuel quantity.
• a measurement of the pressure within the high pressure accumulator 13 is made by a pressure sensor, not shown, to the high pressure accumulator 13th
• a value measured by this pressure sensor is referred to as the actual value of the pressure and later identified by the reference numeral 1 10.
• the ZME 14 is acted upon by a control signal 106.
• the ZME 14 supplies fuel to the high-pressure pump 3.
• the actuating signal 106 is usually determined by a control unit, not shown.
• FIG. 2 shows a schematic block diagram 20 for determining a
• Pressure correction value 104 From a driver's request, an accelerator gradient 100 is determined and fed to a comparator 26 together with a threshold value 124.
• the driver's request essentially corresponds to the position of the accelerator pedal of the motor vehicle to be actuated by a driver. From this driver's request, the accelerator gradient 100 is derived, for example as a percentage of an accelerator pedal travel per unit time. The accelerator gradient 100 is then compared to the threshold 124 in the comparator 26.
• a first activation signal 134 has a first level, which corresponds to an activation when the accelerator gradient 100 exceeds the threshold value 124, that is, when the position of the accelerator pedal changes greatly.
• the first activation signal 134 has a second level which is one Deactivation corresponds to when the accelerator gradient 100 is less than the threshold value 124. A transition from the first to the second level is referred to as triggering.
• the first activation signal 134 is a
• Activation unit 32 is supplied.
• the activation unit 32 is acted upon by a debounce time 126, a correction time 128 and a waiting time 132.
• the correction time 128 is determined by means of a characteristic curve 22 from a rotational speed 122 of the internal combustion engine.
• the waiting time 132 is determined by means of a characteristic curve 24 from the rotational speed 122.
• the activation unit 32 generates a second activation signal 136.
• the second activation signal 136 like the first activation signal 134, has a first and second level.
• the second activation signal 136 is generated based on the first activation signal 134.
• the activation unit 32 ensures that a multiple triggering of the second activation signal 136 by the first activation signal 134 during the debounce time 126 is prevented. For example, a jerky, desired by the driver load reduction to a bouncing of the
• the debounce time 126 avoids multiple triggering of the second activation signal 136.
• the second activation signal 136 is triggered. After the triggering of the second activation signal 136, the second
• Activation signal 136 for the correction time 128 is maintained at its first level and returns to the second level after the correction time 128.
• a ramp function unit 34 is supplied with the second activation signal 136, a zero signal 141, a raw pressure correction value 142 and ramp parameter 138.
• the ramp function unit 34 generates the pressure correction value 104.
• the zero signal 141 corresponds to a zero level of the pressure correction value 104, usually a value of zero.
• the raw pressure correction value 142 is derived from a map 28 of an injection quantity 102 and the rotational speed 122 determined.
• the ramp parameters 138 are used for ramping in and out of the pressure correction value 104.
• the ramp function unit 34 selects the zero signal 141
• the ramp function unit 34 selects the raw pressure correction value 142 to generate the pressure correction value 104.
• one of the ramp parameters 138 is supplied to a first ramp function.
• the first ramp function ensures that the pressure correction value 104 does not jump from the zero level to the raw level.
• Pressure correction value 142 increases or decreases, but over a period of time
• Pressure correction value 104 is proportionally composed of the zero signal 141 and the raw pressure correction value 142, wherein the proportion in the first ramp function shifts over time to the raw pressure correction value 142. If the second activation signal 136 returns to its untripped state, there is a corresponding deceleration of the
• Pressure correction value 104 instead.
• the beginning of the triggered state of the second activation signal 136 corresponds to an activation of the
• Activation signal 136 corresponds to a deactivation of the pressure correction value 104.
• FIG. 3 shows a schematic block diagram 40 of a controller structure for supplying the pressure correction value 104.
• the actual value 110 of the pressure is determined from a controlled system 44 formed essentially by the ZME 14, the actuating device 15, the high-pressure pump 3 and the high-pressure accumulator 13.
• the actual value 1 10 of the pressure is subtracted at a point 146 from a target value 108 of the pressure.
• the target value 108 is inter alia dependent on the driver's request, whereby the driver's request is reflected in the target value 108 with a time delay.
• the result of the subtraction at location 146 is a first control difference 143.
• the first control difference 143 is a first control difference 143.
• the second control difference 144 is applied to a controller 42.
• the controller 42 is usually a PI controller.
• the controller 42 generates the actuating signal 106.
• the actuating signal 106 is fed to the controlled system 44.
• the actuating signal 106 determines the degree of opening of the ZME 14.
• FIG. 4 shows a schematic diagram in two cutouts 50a and 50b.
• the detail 50a shows the schematic diagram with deactivated
• the detail 50b shows the schematic diagram with the pressure correction value 104 activated. Along a time axis t, times t0, t1, t2 and t3 are plotted.
• the time tO is generally referred to as the first time.
• the time t1 is generally referred to as the second time.
• the time t3 is generally referred to as the third time.
• the detail 50b shows an application of the block diagrams 20 and 40 of FIGS. 2 and 3 for avoiding a pressure overshoot in the high-pressure accumulator 13 as it is present in the cutout 50a and explained below.
• the accelerator gradient 100a drops sharply at time t0, stays at a low level, and returns to the previous level before time t2. This corresponds to a removal of the foot from
• Accelerator which means a transition to overrun.
• the threshold value 124 is exceeded.
• the pressure correction value 104a is thus in the deactivated state, which corresponds to the zero signal 141 in FIG.
• the injection amount 102a remains at a nearly same level until the time t2, and decreases in accordance with the transition to the coasting operation after the time t2. This corresponds to the usual procedures when using a conventional engine control unit.
• the control signal 106a remains at a nearly same level until time t2, and drops after time t2.
• the drop of the control signal 106a causes a reduction in the degree of opening of the ZME 14 of Figure 1.
• Time t2 on a nearly the same level After the time t2, the target value 108a of the pressure drops. After the time t2, the actual value 1 10a of the pressure does not follow the desired value 108a of the pressure. In the region of a marking 52a, the actual value 1 10a of the pressure has an overshoot. The overshoot represents an unwanted pressure deviation.
• Overshoot is characterized by an increase of the actual value 1 10a, whereby the target value 108a decreases.
• the actual value 1 10a of the pressure approaches the target value 108a again after reaching a maximum of the overshoot.
• Reason for the overshoot is the hydraulic delay of the closure of the high pressure pump 3 of Figure 1.
• the accelerator gradient 100b drops sharply at time t0, stays at a lower level, and returns to the previous level before time t2. As in section 50a, so also in the
• the schematic block diagram 20 of FIG. 2 is not deactivated.
• an enable signal 134 is generated, resulting in the output of a pressure correction value 104b.
• the pressure correction value 104b is in the deactivated state before the time t0. After time t0, the pressure correction value 104b drops, moves below the previous level, and returns to the deactivated state only at time t3.
• the pressure correction value 104b is generated by the block diagram 20 of FIG. 2 and supplied to the controller structure there according to the block diagram 40 of FIG.
• the injection amount 102b stays at a nearly equal level until the time t2, and falls after the time t2 in accordance with the transition to the coasting mode.
• the control signal 106b remains at an almost same level until the time t0 and drops off after the time t0.
• the drop in the control signal 106b causes a reduction in the degree of opening of the ZME 14 of Figure 1, whereby the high-pressure pump 3 is supplied less fuel per time.
• the target value 108b of the pressure and the actual value 110b of the pressure are at an almost identical level before the time t2. After the time t2, the target value 108b of the pressure and the actual value 110b of the pressure fall off.
• the actual value 1 10b of the pressure points in an area of the marking
• Target value 108b or the falling injection amount 102a can be detected and taken into account at the time t2.
• the pushing operation is already detected at the time t0.
• the actuating signal 106b can be changed in a suitable manner, which in turn means that the actual signal 110b of the pressure no longer has an overshoot.
• the drop of the control signal 106b during the thrust transition is brought forward by the active pressure correction value 104b from the time t2 in the cutout 50a to the time t0 in the cutout 50b. Accordingly, with the pressure correction value 104b activated, the ZME 14 closes sooner than when deactivated
• Pressure correction value 104a An earlier closing of the ZME 14 of Figure 1 has the consequence that an overshoot of the actual value 1 10a is avoided in the mark 52a and a course of the actual value 1 10b sets as in mark 52b.
• the thrust transition can thus already be detected at the time t0 by the evaluation of the accelerator gradient 100 or 100b.
• closing of the ZME 14 in accordance with the actuating signal 106b can already be initiated at the time t0 and thus before the time t2.
• Acceleration from the accelerator gradient 100 can be determined.
• Another embodiment for preventing unwanted deviations of a pressure relates to influencing a boost pressure which is generated by a compressor.
• a charge of the internal combustion engine is done via a compressor.
• the compressor is supplied with a control signal, which is generated according to FIG.
• the compressor generates a pressure, the boost pressure, in a suction pipe which is connected to the inlet of the internal combustion engine. Also, this pressure is subject to changes, as previously
• the pressure correction value 104 is formed according to the block diagram 20 of FIG. 2, fed to a control structure according to the block diagram 40 of FIG. 3, thus avoiding a pressure undershoot or a pressure overshoot of the boost pressure.

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• Engineering & Computer Science (AREA)
• Chemical & Material Sciences (AREA)
• Combustion & Propulsion (AREA)
• Mechanical Engineering (AREA)
• General Engineering & Computer Science (AREA)
• Electrical Control Of Air Or Fuel Supplied To Internal-Combustion Engine (AREA)

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• 2010
  • 2010-06-09 DE DE102010029840.9A patent/DE102010029840B4/de active Active
• 2011
  • 2011-05-18 CN CN201180028335.9A patent/CN102918243B/zh active Active
  • 2011-05-18 EP EP11720472.7A patent/EP2580455A1/de not_active Withdrawn
  • 2011-05-18 WO PCT/EP2011/058046 patent/WO2011154229A1/de active Application Filing

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