ES2204365T3 - ACCUMULATOR FUEL INJECTION CONTROL AND APPLIANCE METHOD. - Google Patents

Abstract

Accumulator fuel injection injection control apparatus, characterized in that it comprises: detection means (14) for detecting a fuel pressure in an accumulator duct (4); estimation means (22) for estimating a pressure of the fuel injected into an engine (1); means (21) for calculating the amount of fuel injection control, to calculate an amount of fuel injection control based on the fuel pressure detected or the estimated fuel pressure; and fuel injection means for injecting fuel into the engine based on the calculated fuel injection control amount, in which: the means (21) for calculating the amount of fuel injection control determine which of the fuel pressure detected and the estimated fuel pressure must be used, based on the instant fuel injection of the injection means.

Description

Injection control device and method of accumulator fuel

Background of the invention 1. Field of the invention

The present invention relates to a method and a accumulator fuel injection control apparatus, for an internal combustion engine, and more particularly, to a method and an accumulator fuel injection control apparatus for an internal combustion engine that is trained to improve the precision of fuel injection control in the state of transition.

2. Description of the related technique

In general, in an internal combustion engine equipped with an accumulator duct such as a common rail or similar, high pressure fuel is fed under pressure from a fuel pump to the accumulator line, and injected from the connected fuel injection valves to the accumulator duct to the combustion chambers of the engine. During the control of the amount of fuel injection, first detects the fuel pressure in the duct accumulator as a fuel injection pressure, and it calculates a required amount of injection as a state of engine performance Next, a value of command for the determination of a valve opening period of fuel injection valves, based on the pressure of  fuel and the amount of injection required. Through the base fuel injection valve operation at command value, fuel injection valves they inject fuel in an amount equal to the amount of required injection

If the fuel pressure in the duct accumulator rises, for example, due to the power of the pressurized fuel through the fuel pump during a period from the aforementioned detection of the fuel pressure until the start of the injection of fuel, fuel injection is performed based on the fuel pressure that is higher than the fuel pressure at the time of setting the command value. In consecuense, the amount of fuel actually injected from the valves fuel injection, exceeds the amount of injection required If that difference between the actual amount of injection of fuel and the amount of injection required, becomes too large, problems such as deterioration of escape properties and the like.

Therefore, as described in the art related, as in the open Japanese patent application to the public no. HEI 6-93915, the difference between a fuel pressure value detected last time and the fuel pressure value detected the second time, it add to the value detected the last time during a state of engine transition operation, and a period of fuel injection (a command value) based on the value added and to the amount of fuel injection required. It is say, the change in fuel pressure during the period that ranges from the detection of a fuel pressure to the start of fuel injection, is predicted based on record of such change, and the predicted value is used to set the fuel injection period instead of the value actual measurement As a result, the injection period of fuel can be properly established by previously taking in account for a change in fuel pressure over a period ranging from the detection of fuel pressure to the Start of fuel injection. In this way, even in the moment of engine transition operation, the amount of fuel injection can be controlled with high precision.

However, according to said injection control of previously used fuel, changing the pressure of fuel that is produced after the detection of a pressure of fuel, is forecast based on a record of the change in fuel pressure Thus, the detected value of the fuel pressure barely changes and remains substantially constant. Even more, in case the fuel pressure changes drastically during a period between moments of respective detection, the change in fuel pressure already It cannot be predicted. Of course, there are no countermeasures that can be adopted against such circumstances.

In addition, in a transitional operational state, in that the operating conditions change abruptly, the pressure Fuel injection also changes abruptly. So, in the instant of abrupt change of operating conditions, it is used a predictive value, which mainly takes into account a change of the fuel injection pressure between an instant of actual measurement of the fuel injection pressure and a instant fuel injection through injectors, to calculate a fuel injection amount.

However, there is an error between the value predictive and the actual measurement value due to the discrepancy in the resulting prediction of environmental conditions. So, if the predictive value is used despite the fact that there is a actual measurement value available immediately before the fuel injection at the instant of transition, accuracy in the amount of fuel injection control is reduced, what which can negatively affect exhaust emissions, noise, and the like

In order to prevent that decrease in precision in fuel injection control, may result possible to shorten a period from the detection of the fuel pressure until the start of the injection of fuel, for example, by detecting the pressure of fuel immediately before the start of the injection of fuel. However, in reality, there is a need for calculate a control command value to activate the valves of fuel injection during that period. In terms of load calculation and the like, the period cannot be shortened by unlimited form

In other words, when an attempt is made to always make use of a real pressure measurement value of fuel injection in order to increase accuracy in the calculation of the amount of fuel injection control, in in case there is not enough time between the instant of the fuel injection by the injectors and the instant for measuring the actual measurement value of the pressure of fuel injection, the actual pressure measurement value Fuel injection cannot be reflected on the control Fuel injection In order to solve this problem, it may be possible to adopt a method in which the moment of measurement of a real measurement value of the injection pressure of fuel changes depending on operating conditions (it is say, from the instant of fuel injection), mainly in which the instant for the measurement of a real measurement value of the fuel injection pressure is advanced by proportion to the advance of the injection moment of fuel.

However, according to this method, if the instant of measurement of a real pressure measurement value fuel injection, the measurement is actually carried out during the pump pressure feed stroke, so that the fuel injection pressure is obtained during the pressure feed stroke of the pump. In this case, the fuel injection pressure during the run of Pressure supply of the pump is different from the pressure of fuel injection at the time of the start of the injection made out of fuel. Therefore, if you anticipate the moment you measures the actual measurement value of the injection pressure of fuel, the accuracy of the control amount of fuel injection

Also, if you change the time for measurement of a real measurement value of the injection pressure of fuel depending on operating conditions, particularly, from the moment of fuel injection, the control Global is complicated.

In conclusion, according to the injection control of previously used fuel, it is impossible to establish a fuel injection period that is adequate to harmonize a quantity of actual fuel injection with an amount of required injection Therefore, the reduction in the precision of fuel injection control.

Summary of the invention

An object of the present invention consists in provide a method and an injection control apparatus of accumulator fuel that is simple and shows high precision of fuel injection control at the instant of transition.

The fuel injection control device of accumulator, according to the present invention, has been provided with means of detection to detect a fuel pressure in a accumulator duct, calculation means to calculate a pressure of fuel injected into an engine, means of calculating the quantity fuel injection control to calculate an amount fuel injection control based on the pressure of fuel detected or at estimated fuel pressure, and fuel injection means for injecting fuel into the engine based on the amount of fuel injection control It has been calculated. The essence of the present invention consists in that the means of calculating the amount of injection control of fuel determine which of the fuel pressure detected and the estimated fuel pressure must be used, instantly based on fuel injection of the means of injection.

As a result, at the time of transition, can reduce the frequency at which the control of fuel injection using predictive values undefined, and the control accuracy of fuel injection

In addition, the object of the invention is resolved. also by the method of claim 12.

Although this summary does not describe all characteristics of the present invention, it should be understood that any combination of the characteristics set forth in the dependent claims, is within the scope of the present invention

Brief description of the drawings

Figure 1 is a structural view of a accumulator fuel injection control apparatus for an internal combustion engine, according to a first embodiment of the present invention

Figure 2 is a graph illustrating a relationship between the moment of fuel injection and the measurement time of a real pressure measurement value of fuel injection in case the value of actual measurement to calculate an injection amount of fuel.

Figure 3 is a graph illustrating a relationship between the moment of fuel injection and the instant measuring the actual measurement value of the pressure of fuel injection, in case a value is used predictive to calculate an injection amount of fuel.

Figure 4 is a flow chart showing a process of calculating an injection amount of fuel.

Figure 5 is a flow chart showing a process of calculating a predictive value of the pressure of fuel injection

Figure 6 is a schematic structural view of a high pressure fuel injection system of a diesel engine according to a second embodiment of the present invention.

Figure 7 is a time diagram showing a pattern of changing the fuel injection pressure, caused by a fuel leak or similar.

Figure 8 is a time diagram showing a pattern of changing fuel injection pressure caused by a fuel feed under pressure and Similary.

Figure 9 is a flow chart showing a process of calculating a fuel injection period according to the second embodiment.

Figure 10 is a flow chart showing a process of calculating a quantity of pressure change according to The second embodiment.

Figure 11 is a graph showing the pressure of fuel and the amount of fuel injection in relationship with the fuel injection period.

Figure 12 is a graph showing the pressure of fuel and the amount of injection required in relation to The sensitivity coefficient.

Figure 13 is a flow chart showing a process of calculating a fuel injection period according to a third embodiment of the present invention.

Figure 14 is a flow chart showing a process of calculating a fuel injection period according to a fourth embodiment of the present invention.

Figure 15 is a flow chart showing a process of calculating a quantity of pressure change according to the Fourth embodiment

Figure 16 is a timing diagram that shows a pattern of change in the injection pressure of fuel caused by pilot injection, injection Main, and similar.

Figure 17 is a flow chart showing part of a process of calculating an amount of change in the pressure according to a fifth embodiment of the present invention.

Description of preferred embodiments

In the following, embodiments will be described of the present invention with reference to the drawings.

First Realization

Figure 1 schematically shows a structure of a fuel injection control apparatus of accumulator for an internal combustion engine, according to the present invention. In a 1 engine (a four-cylinder engine in this case), injectors 2 have been arranged to inject fuel into high pressure in the combustion chambers of the respective cylinders Fuel injection from injectors 2 to the motor 1 is controlled by means of the opening and closing of 3 solenoid injection control valves. The injectors 2 are connected to a common rail 4 that is used usually for the respective cylinders. While the valves 3 electromagnetic injection control are open, it inject fuel from common lane 4, from injectors 2 towards the combustion chambers of the engine 1.

Since the rail fuel pressure common is the fuel injection pressure, the common lane 4 you need to build up an adequate fuel pressure that correspond to an operational state. For this reason, it has connected a high pressure pump 7 that is capable of supplying high pressure fuel, to common lane 4, through a feed duct 6 and a check valve 5. The check valve 5 allows fuel to circulate only in a single direction, from the high pressure pump 7 to the common lane 4.

A pressure sensor 14 detects the pressure of fuel injection injected from injector 2 to the combustion chamber of engine 1, particularly the pressure of fuel (rail pressure) of the common rail.

The high pressure pump 7 feeds a pressure required amount of fuel, which has been sucked since a fuel tank 8 by means of a feed pump 9 low pressure, to common rail 4 by movement reciprocal of two plungers (not shown), through a cam (not shown) that synchronizes with the rotation of motor 1. This cam has a two phase ascensional characteristic different (see figures 2 and 3).

The high pressure pump 7 is equipped with two corresponding discharge quantity control devices 10 To the two pistons. Each of the control devices 10 of discharge quantity is equipped with a valve (not shown) of the high pressure pump, to open and close an orifice of 7 high pressure pump inlet. This pump valve high pressure adjusts the effective pressure feed stroke of the high pressure pump 7, and controls an amount of discharge. With the control of this amount of discharge, the Common rail pressure based on the difference between the quantity of fuel discharged from the common lane through the fuel injection, and a quantity of fuel supplied from the high pressure pump.

The operations of the valves 3 electromagnetic injection control valves and the high pressure pump of quantity control devices 10 discharge, are controlled by a control signal obtained at the output of an electronic control unit 11 (cited in successive simply as "ECU"). Detection signals from a motor rotation speed sensor 12 and from a throttle opening degree sensor 13, are introduced into ECU 11. Also, input signals from sensor 14 of pressure and various sensors for temperature detection of coolant, intake air temperature, pressure of the intake air and the like, are introduced in ECU 11. The ECU 11 determines an operational state of the engine based on those input signals, performs arithmetic processing according to a default program, and outputs optimal control signals for injection control solenoid valves 3 and for discharge quantity control devices 10. Even if has not been represented, the ECU 11 has been equipped with memories (RAM, ROM) to store the detected data, control programs, and the like ECU 11 has been equipped with a part 21 that calculates the amount of fuel injection and with a part 22 that calculates the predictive value of fuel injection pressure, which will be described later.

Figures 2 and 3 are graphs that illustrate a relationship between the moment of fuel injection and the instant for the measurement of a real measurement value of the fuel injection pressure. Figure 2 shows a case in that the actual measurement value is used to calculate an amount Fuel injection Figure 3 shows a case in which use a predictive value to calculate an injection amount made out of fuel.

Rail pressure increases due to fuel pressure feed through the pump in a interval indicated by the striped areas in figures 2 and 3, after having fallen as a result of a decrease in amount of fuel in the lane resulting from the injection of fuel.

The pressure sensor 14 detects the pressure (a P2 rail pressure in figure 3) of the fuel injected into the combustion chambers of the engine 1 from the injectors 2 in a first moment t1.

In an instant t120, the part 21 that calculates the fuel injection amount calculates a second instant t2 for the beginning of fuel injection by means of 2 injectors from an engine operating state. In this case, there are two fuel injection pulses as injection pilot and as the main injection that must be taken into account. The part 21 that calculates the amount of fuel injection compare a first time T1 corresponding to the difference between the first moment t1 and the second moment t2, with a second time T2 required for arithmetic processing of the amount of fuel injection based on a real measurement value of the fuel injection pressure detected in the first instant t1.

As shown in Figure 2, if the arithmetic processing of the amount of fuel injection based on the actual measurement value of the injection pressure of fuel measured in the first instant t1, is produced on time for the second instant t2, which is an injection moment of fuel by means of the injectors 2, namely, if the first time T1> the second time T2, the part 21 that calculates the fuel injection amount performs the calculation of a amount of fuel injection at time t2, using the result of arithmetic processing of the actual measurement value of the fuel injection pressure detected in the first instant t1. Thus, compared to the case in which it is used always a predictive value, the control accuracy of fuel injection

As shown in Figure 3, if the arithmetic processing of the amount of fuel injection based on the actual measurement value of the injection pressure of fuel measured in the first instant t1, is not produced on time for the second instant t2, which is the injection moment of fuel by injectors 2, namely, if the first time T1 <the second time T2, the part 22 that calculates the value fuel injection pressure predictive calculates, in the instant t_ {exp}, a predictive value of injection pressure of fuel at the first time t1 based on the value of actual measurement of fuel injection pressure in one cycle anterior (a rail pressure P1 in figure 3). On the other hand, the part 21 that calculates the amount of fuel injection calculate a fuel injection amount in the second instant t2, using the predictive value calculated by the part 22 which calculates the predictive value of injection pressure of fuel.

The result of the injection control calculation at time t_ {exp} is used to calculate an amount of fuel injection during pilot injection. The calculation of the injection control is also performed in the first instant t1. The result of the first injection control calculation instant t1 is used to calculate an injection amount of fuel during the main injection. In the instant that has calculated the amount of fuel injection injection during the main injection, the moment when you can the actual measurement value be used. In this way, the actual measurement value of fuel injection pressure.

On the contrary, in the case shown in the Figure 2, injection control calculations for injection pilot and for the main injection, they are processed together. For both pilot injection and main injection, it is used to the calculation the last actual measurement value of the pressure of fuel injection

In this way, the part 21 that calculates the fuel injection amount determines which of the actual measurement value and the predictive value of the pressure of fuel injection must be used to calculate a fuel injection amount, based on the first time T1 between the first instant t1 and the second instant t2, and the second T2 time required for arithmetic processing of an amount fuel injection derived from the actual measurement value of fuel injection pressure measured in the first instant t1.

As shown in figure 3, if you go ahead the crankshaft angle corresponding to an instant of injection of fuel of the injectors 2, the second instant t2 is advanced with respect to an instant (t1 + T2) in which the arithmetic processing of the amount of fuel injection based on the actual measurement value of the injection pressure of fuel. Therefore, the actual measurement value cannot be used.

Figure 4 is a flow chart to calculate fuel injection pressure and perform the processing arithmetic of the amount of fuel injection, according to a injection control sequence that runs every time the crankshaft rotates a predetermined angle.

First, the part 21 that calculates the fuel injection amount determines if it has been reached or no (S41) the instant t120 to calculate a second instant t2 in which the injectors 2 inject fuel. If it is determined that t120 has reached the moment, the process advances to S42. Whether determines that the instant t120 has not been reached, the process advance to S47.

In S42, part 21 that calculates the amount of fuel injection calculates a second instant t2 in which 2 injectors inject fuel, based on a state Engine operating and similar. Depending on the operational status of the engine, the part 21 that calculates the amount of injection of fuel also determines whether the injection should be carried out of fuel once or twice (the so-called pilot injection).

Next, part 21 that calculates the fuel injection amount determines whether the time (t1 + T2) after the period of time T2 required for the calculation of a amount of fuel injection from the first moment t1 when the actual measurement value of the pressure of fuel injection, has advanced or not with respect to the second time t2, which constitutes an injection moment of fuel (S43). Here, it is also possible to calculate an instant of fuel injection and a time required to calculate the amount of fuel injection each time, and compare them. Without However, if the time required to calculate the amount of fuel injection is constant regardless of status engine operation, the determination can be made based on the difference between a fuel injection instant and a Actual measuring moment of injection pressure. Also, if the actual measuring moment of fuel injection pressure it is also constant regardless of the operational state of the engine, the determination can be made only on an instant basis to which the crankshaft angle corresponds at the moment of fuel injection

If the result is YES in S43, the process advances until S45 where the part 21 that calculates the amount of injection Fuel set an indicator off.

On the contrary, if the result is NO in S43, the process advances to S44 in which the loyal indicator is switched on. So, part 21 that calculates the amount of fuel injection calculates an injection amount of fuel in the second instant t2 using a value fuel injection pressure predictive calculated by the part 22 that calculates the predictive value of injection pressure of fuel (S46). Step S46 corresponds to an operation made at the instant t_ {exp} shown in figure 3. A concrete method of calculating a predictive value at that stage, goes to be described later with reference to figure 5.

After it has been determined in S41 that the instant t120 has not been reached (NO), or after the indicator has gone out as a result of the determination made in S43 (S45), or after the amount has been calculated fuel injection in the second instant t2 with the use of predictive value (S46), the part 21 that calculates the fuel injection amount determines if it has been reached or not a first moment when the pressure sensor 14 detects a fuel injection pressure injected into the chambers of combustion of engine 1 from injectors 2 (S47).

If it is determined that the first instant has been reached, the pressure sensor 14 detects an injection pressure of fuel from the fuel injected into the chambers of combustion of engine 1 from injectors 2 (S48). But the process skips the measurement stage of an injection pressure of fuel and the stage of calculating an injection amount of fuel based on the actual measurement value of the pressure of fuel injection, and advances to a stage of realization fuel injection (not shown) or similar, in the Current sequence Injection pressure detection of fuel in S48 includes performing an A / D conversion of a analog output of sensor 14, and recover the output converted to ECU 11.

Next, part 21 that calculates the fuel injection amount determines if the indicator has been or not turned off (S49). If it is determined that the indicator has been off, the part 21 that calculates the injection amount of fuel calculates a fuel injection amount using the result of arithmetic processing of the value of actual measurement of the fuel injection pressure calculated in S48 (S50).

After the result has been determined as NOT in S49, or after the processing is finished in S50, the process proceeds to the injection completion stage of fuel (not shown) or similar, in the current sequence.

Figure 5 is a flow chart showing a process of calculating a predictive pressure value of fuel injection used in S46.

First, the part 22 that calculates the value fuel injection pressure predictive calculates a quantity P_ {p} of pressure feed of pump 7 high pressure based on the amount of fuel intake, a fuel temperature, a rotational engine speed, and a fuel injection pressure P_ {pre} in one cycle previous (S51).

Next, part 22 that calculates the value fuel injection pressure predictive calculates a Pr amount of injector leakage based on a period of electricity supply, a fuel temperature, a rotational motor speed and rail pressure P_ {pre} in an earlier cycle (S52). The amount of injector leakage according to mentioned herein, refers to a quantity of fuel that is discharged (mainly injection of fuel) through the injectors from the common rail 4.

After this, the part 22 that calculates the value fuel injection pressure predictive calculates a K_ {p} coefficient of elasticity of fuel volume in the common lane 4 based on fuel temperature and P_ {pre} rail pressure from a previous cycle (S53).

By the respective parameters calculated in the above mentioned stages, how much fuel is calculated has been supplied to, and downloaded from, a volume default of common lane 4 after a previous measurement of the fuel pressure As a result, it is possible to calculate a amount of change in the amount of fuel from a measurement previous fuel pressure. Fuel quantity which has changed causes a change in fuel pressure in the common lane 4. In this case, taking into account the influence of the volume elasticity of rail fuel common, a final fuel pressure P_ {exp} is forecast at the common lane (P_ {exp} = P_ {pre} + (P_ {p} - P_ {r}) x K_ {p} / V_ {r}) (S54).

As described so far, according to the present embodiment, part 21 that calculates the amount of fuel injection calculates an injection amount of fuel using a real pressure measurement value of fuel injection when the first time T1 is longer than the second time T2, and calculates an injection amount of fuel using a predictive value of injection pressure of fuel when the first time T1 is equal to, or shorter that, the second time T2. Consequently, even though not change the moment for measuring an injection pressure of fuel, the amount of fuel injection can be calculated using a real pressure measurement value of fuel injection, as far as possible. Thus, it is reduced the frequency with which the control is performed using a value indefinite predictive in the transition time. In consecuense, the accuracy of the fuel injection control is improved, and it is possible to make use of a predictive value corresponding to instant fuel injection.

In addition, since the instant of injection of fuel is compared directly to the instant of completion of the control, it increases the frequency with which it can be used the actual measurement value of the injection pressure of fuel.

In the present embodiment, based on the rotational speed of the motor can determine which of the value of actual measurement and predictive value will be used to calculate a quantity of fuel injection.

The time for the crankshaft angle during the high speed motor rotation, is shorter than time for that crankshaft angle during low speed rotation the motor. While the instant (t1) for the actual measurement of the fuel injection pressure and instant (T2) for the Fuel injection are considered as crankshaft angles, the time (T2) for calculating the amount of fuel injection It is determined as a time instead of as a crankshaft angle. Therefore, even if the moment (t1) of actual measurement of the fuel injection pressure and instant (t2) injection of fuel correspond to the same crankshaft angle, the time (T1) from the moment (t1) for pressure detection of fuel up to the moment (t2) for the injection of fuel, may differ depending on rotational speed the motor. Thus, sometimes, the duration relationship between T1 and T2 changes.

When an injection amount of fuel based on the rotational speed of an engine, can be carried out the stage of determining if the speed Rotational motor is or not less than a predetermined N1 value, instead of S43 of the flow chart shown in Figure 4.

If it is determined that the rotational speed of the engine is less than N1 [rpm], the process advances to S45 where the indicator goes out. If it is determined that the rotation speed of the motor is equal to, or greater than, N1 [rpm], the process advances to S45 where the part 21 that calculates the amount of injection of Fuel sets the indicator on.

The rotational speed N1, as mentioned Here, it can be selected arbitrarily. It is preferable select a rotational speed through which the frequency, with which you set the injection moment of fuel when the value obtained by the time conversion of a difference in crankshaft angle between the instant of measurement of fuel pressure (t1 in Figures 2 and 3) and the instant of fuel injection for a rotational speed at that time exceeds the time required to calculate the amount of fuel injection, change.

If the fuel injection amount is calculate in this way, the actual measurement value and the value predictive distinguish each other only by determining if a detection signal from speed sensor 12 Rotational motor is or is not at a level below a speed default rotational. Therefore, the arithmetic charge applied to the ECU can be reduced.

As described so far, it is possible calculate a fuel injection amount using a actual measurement value of the fuel injection pressure in A certain measure. In addition, it is also possible to reduce the load arithmetic applied to the ECU.

In addition, it is possible to distinguish between a value of actual measurement of fuel injection pressure and a value predictive of fuel injection pressure doing reference, not only at a rotational speed but also at a two-dimensional plane of rotational speed and instant of fuel injection, and the like.

As described so far, this embodiment makes it possible to provide a control apparatus fuel injection tank, which has a good precision of fuel injection control at the instant of transition.

Second Realization

Figure 6 schematically shows an engine 110 and a high pressure fuel injection system for the same.

This high fuel injection system pressure is equipped with injectors 112 provided so that correspond to respective cylinders # 1 to # 4 of engine 110, a common rail 120 to which respective injectors 112 have been connected, a fuel pump 130 for the pressure feed of the fuel from fuel tank 114 to lane 120 common, and an ECU 160.

A safety valve 122 has been fixed to the common lane 120 Safety valve 122 has been connected to the Fuel tank 114 through a discharge passage 121. Yes the fuel pressure (rail pressure) inside the common lane exceeds a predetermined upper limit value, the safety valve 122 opens in order to reduce the Pressure.

112 injectors, which consist of electromagnetic valves that open and close by means of ECU 160, inject the fuel fed from lane 120 common towards combustion chambers (not shown) of respective # 1 to # 4 cylinders. The respective injectors 112 are have also connected to the fuel tank 114 through the 21 download passage. Even when all 112 injectors are closed, part of the fuel fed from lane 120 common until the respective injectors 112 constantly escapes on injectors 112. The fuel that has escaped in this way, it is returned to the fuel tank 114 through passage 121 of download.

ECU 160 performs control in relation to the fuel pressure supply via pump 130 fuel, and fuel injection by means of 112 injectors. The ECU 160 is composed of a memory 164 for store various programs, functional data and the like, a CPU 162 to perform various arithmetic processes, and Similar.

Also, several sensors for the detection of operating state of the engine 110 and the fuel status in the Common rail 120, and the like, have been connected to ECU 160. Detection signals from these sensors are introduced in ECU 160.

For example, a speed sensor 165 Rotational has been provided in the vicinity of a crankshaft (no represented) of the motor 110, and a discrimination sensor 66 of cylinder has been provided in the vicinity of the camshaft (no represented). Based on the detection signals introduced from the respective sensors 165, 166, the ECU 160 calculates the Crankshaft rotational speed (a rotational NE speed of the engine), and the rotational angle of the crankshaft (an AC angle of the crankshaft).

In addition, a sensor 167 of the accelerator near the accelerator pedal (no represented), and detects a detection signal corresponding to an amount of accelerator pedal depression (an ACCP degree of throttle opening). The common lane 120 has been endowed with a fuel pressure sensor 168, which outputs a detection signal corresponding to a fuel pressure (a real fuel PCR pressure). A temperature sensor 169 of fuel has been provided in the vicinity of a hole 38 of discharge of the fuel pump 130. The 169 sensor of fuel temperature outputs a detection signal corresponding to a fuel temperature (a temperature Fuel THF). ECU 160 detects the ACCP degree of opening of accelerator, a real PCR fuel pressure, and a temperature THF fuel based on detection signals from the respective sensors 167 to 169.

The fuel pump 130 has been equipped with a drive shaft 140 rotatably driven by the crankshaft of the 110 engine, a feed pump 131 that operates based on the impeller shaft rotation 140, a pair of feed pumps driven by an annular cam 142 formed in the drive shaft 140 (a first feed pump 150a and a second pump 150b of feeding), and the like.

Feed pump 131 sucks fuel in the fuel tank 114 from an intake port 134, through an admission passage 124, and supplies the fuel to the first feed pump 150a and to the second pump 150b of  feed at a predetermined feed pressure. further of the fuel that has been sucked from the hole 134 of admission, excess fuel that is not fed to any of said first feed pump 150a and second pump 150b of feed, is returned to the fuel tank 114 from a discharge hole 136, through discharge passage 121.

Both first feed pump 150a and second feed pump 150b, are cam type pumps inside. These pumps pressurize the fuel fed from the feed pump 131 to a higher pressure (for example, from 25 to 180 MPa), based on alternative movements of a plunger (not shown), and pressure feed the pressurized fuel to common rail 120 from a hole 138 download, through the passage 123 download. The bombs 150a, 150b of feeding perform such feeding operation at fuel pressure alternately and intermittently.

The fuel pump 130 has been provided with a first and second valves 170a, 170b adjustment, to adjust the amounts of fuel fed under pressure from the pumps 150a, 150b feed, respectively. Both valves 170a, 170b adjustment are designed as solenoid valves that they are operated by ECU 160, so that they open and close.

Figure 7 is a time diagram showing the moments for the suction of fuel through, and the fuel pressure feed from the respective pumps 150a, 150b power, resulting in a pattern of change in the fuel injection pressure of the leakage of fuel, and the like.

The respective power pumps 150a, 150b alternatively suck fuel towards the pump 30 of fuel with phases of the crank angle CA (C: Angle Crank, Crankshaft Angle) that are offset from each other in 180º AC. Similarly, the 150a, 150b power pumps Respectively feed the fuel alternately from the fuel pump 130 in phases that are deflected each one the other in CA 180º.

As indicated with (c) in Figure 7, the first adjustment valve 70a opens during the stroke of admission of the first feed pump 150a, in order to start the suction of fuel, and it closes in an instant default (crank angle CA) in order to stop the fuel suction All the fuel that has been sucked in this way it is pressurized with the pressure feed stroke which follows the admission race, and is fed under pressure from the first feed pump 150a to common rail 120. The amount of fuel fed under pressure from the first pump 150th fuel supply, can be adjusted by changing the closing moment of the first adjustment valve 170a.

For example, as indicated by the alternate long and short dotted lines in (c) and (d), if delayed the instant (crankshaft angle CA) for closing the first adjustment valve 70a to thereby increase the period of valve opening of that, the suction period of fuel through the first feed pump 150a is prolongs Thus, as a result of the increase in the amount of fuel intake, the amount of fuel fed to Pressure increases. In addition, if the time to close the first adjustment valve 170a is delayed in this way, the instant (AC angle of the crankshaft) for the start of the feed to fuel pressure from the first feed pump 150a goes ahead at a crankshaft angle that is equal to the amount of time delay. As a result, the pressure feeding period of Fuel is prolonged.

On the other hand, as indicated by two alternate long and short dotted lines in (c) and (d), if the instant for the closing of the first valve 170a of adjustment is move forward to reduce the opening period of the valve for that, the period of fuel suction through the First feed pump 150a shortens. So as a result of the decrease in the amount of fuel intake, the amount of fuel fed under pressure is reduced. Furthermore, if the instant for the closing of the first adjustment valve 170a is that way, the moment for the beginning of the fuel pressure feed from the first pump 150a power is delayed at an AC angle of the crankshaft that is equal  to the amount of progress. As a result, the feeding period Fuel pressure shortens.

Similarly, with the delay or advancement of instant (AC angle of the crankshaft) for closing the second adjustment valve 70b, the amount of fuel fed to pressure from the second pump 150b feed can be changed In addition, the instant for the start of feeding to fuel pressure from the second feed pump 50b is advanced or delayed at a crankshaft angle that is equal to the amount of delay or advance of the closing period of the valve of the same.

The moments for the start of the suction of fuel through, and for just feeding to fuel pressure from, pumps 150a and 150b from respective feeding, are established in constant instants (AC angles of the crankshaft). The moments for the start of the fuel pressure supply from the respective pumps 150a, 150b power, can be calculated based on periods of opening of the valve of the respective valves 170a, 170b adjustment. The amounts of fuel fed to pressure from the respective pumps 150a, 150b feed by crankshaft unitary CA angle (cited below as "KQPUMP fuel pressure feed ratio"), they are equal to each other, and always constant regardless of the instants of pressure feed start of fuel. Consequently, the total amounts of fuel pressure fed from the respective pumps 150a, 150b of feeding during periods of pressure feeding, can be calculated by multiplying the periods of pressure feeding by the pressure feed KQPUMP ratio of fuel.

ECU 60 sets an objective pressure of the fuel injection pressure based on an operational state the motor. Based on the difference between the target pressure and the actual fuel PCR pressure detected by a sensor 68 of fuel pressure, ECU 60 controls valves 170a, 170b adjustment mentioned above, so that the fuel injection pressure becomes equal to the pressure objective.

For example, if the actual PCR pressure of fuel is less than the target pressure, the pressure of fuel injection rises delaying the instants of opening for the respective valves 170a, 170b adjustment, and increasing a quantity of fuel fed under pressure. By On the other hand, if the actual PCR fuel pressure is greater than the target pressure, the injection pressure of fuel rises ahead of the closing moments of the respective valves 170a, 170b adjustment, and reducing the amount of fuel fed pressure, and the injection pressure of Fuel is reduced by fuel injection.

Performing such control over the fuel pressure, the injection pressure of fuel at a pressure suitable for the operating state of the motor.

In addition, ECU 160 calculates the amount of required injection based on the operating state of the engine, and Calculate the fuel injection period (valve period open) based on the amount of injection required and the pressure Fuel injection (the actual PCR fuel pressure). Based on the fuel injection period so calculated, the injectors 12 are powered by ECU 60 to be opened and closed.

Here, the value of the injection pressure of fuel when an injection period of fuel, especially the actual fuel pressure PCR detected by the fuel pressure sensor 168, not always matches the value of the fuel injection pressure in the start time of the fuel injection.

For example, as described in what before, fuel from common rail 120 escapes constantly towards the fuel tank 114 through the injectors 112. Thus, as shown in Figure 7, the pressure of PCR1NJ fuel injection at the start time of the fuel injection can become less than the pressure Actual fuel PCR due to fuel leakage. Alternatively, as shown in Figure 8, if the period of Pressure supply of the fuel pump 130 is prolonged and the fuel pressure feed starts before at the beginning of the fuel injection, the injection pressure of PCR1NJ fuel at the instant of injection start fuel can become greater than the actual PCR pressure of fuel due to fuel pressure feed.

In the present embodiment, a change is estimated in fuel injection pressure from detection of the actual PCR fuel pressure until the beginning of the fuel injection, and the injection pressure change of fuel is reflected in the calculation of an injection period of fuel.

The control processes in relation to said fuel injection, will be described in what follows with reference figures 9 to 12.

Figures 9 and 10 are flow charts that show calculation processes of an injection period of fuel. The ECU 160 carries out a series of processes shown in those respective flowcharts as handling of interruption at intervals of a predetermined crankshaft angle (180º AC).

First, in stage 100, ECU 160 detects a real PCR fuel pressure. As shown in Figures 7 and 8, the moment at which the PCR pressure is detected actual fuel, particularly, the instant it interrupts the current sequence, it is set at the moment when the respective supply pumps 150a, 150b are switched from an admission race to a feeding race to pressure (the instant the crankshaft angle CA reaches the angles CA0, CA1, CA2 and CA3 shown in the drawings respective).

In step 200, the amount of injection QFIN required is calculated based on the ACCP degree of opening of accelerator, at the NE rotational speed of the engine, and the like. TO then, in step 300, a TQFINB period of basic injection, based on the amount of injection QFIN required and at the actual PCR fuel pressure. The QFIN amount of required injection and the actual PCR fuel pressure in relation with the basic injection period TQFINB, they are calculated in a way prior by experiments and the like, and stored in the Memory 164 of ECU 160 as functional data for the calculation of TQFINB period of basic injection.

Figure 11 shows the functional data in Functional map form. The TQFINB basic injection period is calculates as a period that turns out to be longer in proportion to the increase in the amount of QFINB injection required and with the decrease in the actual PCR fuel pressure.

Then, in step 400, ECU 60 Calculates a DPCR amount of pressure change. The DPCR amount of pressure change is the amount of pressure change of fuel resulting from the fuel pressure feed, or fuel leakage, during a period from Detection of the actual PCR fuel pressure (CA0 to CA3 in the Figures 7 and 8), until the beginning of the fuel injection by  medium of injectors 112 (crankshaft angle range: see (a) in figure 7 and (a) in figure 8) (the period will be referred to in the following as "APCR period for estimating pressure change ").

Figure 10 is a flow chart showing in detail a process of calculating a DPCR amount of change of Pressure. In step 402, ECU 160 calculates an APUMP period of pressure feed. The APUMP period of pressure feed (see (a) in Figure 8), is a period (angle range of crankshaft) into which fuel is fed under pressure during APCR period of pressure change estimate.

First, when the period is calculated Pressure feed APUMP, ECU 160 calculates a period of start of pressurized feeding of the fuel pump 130 in instant basis for closing the respective valves 170a, 170b adjustment, as set during a run of admission prior to the current start of feeding to fuel pressure For example, if the present instant of interrupt coincides with an instant CA1 shown in figure 8, The pressure feed start period is calculated based on the valve closure periods that are established during a period from CA0 to CA1. Similarly, if the instant of interrupt coincides with an instant CA2, the start period of Pressure feed is calculated based on closing periods Valves established during a period from CA1 up to CA2.

Next, ECU 160 compares the instant of pressure feed start with the start instant of fuel injection that has been calculated separately. If he Pressure feed start time is delayed with respect instantly start fuel injection, especially to unless the fuel pressure feed is carried out prior to the start of the fuel injection, the APUMP period of pressure feed is calculated as zero. By other part, if the feed start time is advanced under pressure with respect to the injection start period of fuel mainly if the pressure feed of fuel is started before the start of the injection of fuel, the period between the instant of injection start of fuel and the instant of pressure feed start Calculates as the APUMP period of pressure feed.

Once the APUMP feeding period to pressure has been calculated that way, ECU 160 calculates, in the step 404, a QPUMP amount of pressure feed of fuel during the APCR change estimate period of pressure according to the calculation formula (1) shown at continuation.

QPUMP = APUMP x KQPUMP ... (1)

APUMP: pressure feeding period

KQPUMP: pressure feed ratio of fuel

Next, ECU 160 calculates a period TLEAK fuel leak. The leakage TLEAK period of fuel is obtained by conversion of the APCR period of pressure change estimate, which is expressed as a unit of angle of the crankshaft, in a time. ECU 160 calculates the period TLEAK fuel leak according to the calculation formula (2) that show below.

TLEAK = K x APCR / NE ... (2)

APCR: change estimate period of Pressure

NE: motor rotational speed

K: conversion constant

In step 408, the QLEAK amount of fuel leak during the APCR change estimate period pressure, based on the TLEAK period of fuel leakage, to the actual PCR fuel pressure and at the THF temperature of fuel. The QLEAK amount of fuel leakage tends to increase in proportion to the increase in the leakage TLEAK period of fuel, to the increase in the actual fuel pressure PCR, and the increase in the THF temperature of the fuel. The term TLEAK fuel leakage, the actual fuel PCR pressure and THF fuel temperature in relation to QLEAK quantity Fuel leakage are previously calculated by experiments and the like, and are stored in memory 164 of ECU 160 as functional data for the calculation of the QLEAK amount of leakage of fuel.

Next, in step 410, a volume elasticity coefficient E based on PCR pressure actual fuel and fuel THF temperature. The volume elasticity coefficient E tends to increase by proportion to the increase in the actual fuel PCR pressure and to the decrease in the THF temperature of the fuel. The pressure Actual fuel PCR and fuel THF temperature in relationship with the volume elasticity coefficient E, it they are previously calculated by experiments and the like, and stored in memory 164 of ECU 160, as data functional.

After having calculated the QPUMP quantity Fuel pressure feed, QLEAK amount of leakage fuel and volume elasticity coefficient E, the ECU 60 calculates, in step 412, a DPCR amount of change of pressure according to the calculation formula (3) shown at continuation.

DPCR = E x (QPUMP - QLEAK) / VCR ... (3)

E: volume elasticity coefficient

QPUMP: amount of pressure feed of fuel

QLEAK: amount of fuel leakage

VCR: common lane volume

As evident from the calculation formula (3), if the QPUMP quantity of fuel pressure feed is more than the QLEAK amount of fuel leakage, the amount DPCR pressure change is calculated as positive value. For him Otherwise, if the QLEAK amount of fuel leakage is greater than the quantity of fuel pressure feed QPUMP, the DPCR amount of pressure change is calculated as a value negative.

After having calculated the DPCR amount of pressure change, the ECU 160 moves the process to the stage 500 shown in Figure 9, and calculates a TQPCR coefficient of sensitivity based on the amount of injection QFIN required and a the actual PCR fuel pressure.

In case the injection pressure of fuel has been changed to a different value of the PCR pressure actual fuel during the APCR change estimate period pressure, if the respective injectors 112 are actuated on the basis to the TQFINB period of basic injection, the amount of injection actual fuel deviates from the injection QFIN amount required The TQPCR sensitivity coefficient is obtained by conversion of the amount of fuel injection that is diverted of a unit change amount at the time of said change of the fuel injection pressure (for example, 1 MPa) towards an amount of deviation from the injection period of fuel.

The TQPCR coefficient of sensitivity and the QFIN amount of injection required in relation to PCR pressure actual fuel are previously calculated by experiments and similar, and stored in memory 164 of ECU 160 as data  functional for the calculation of the TQPCR sensitivity coefficient. Figure 12 shows the functional data in map form functional. The TQPCR sensitivity coefficient is calculated as a value that becomes greater in proportion to the increase in QFIN amount of injection required and the decrease in Real PCR fuel pressure.

Then, in step 600, ECU 160 calculates the TQFINH correction value of the injection period according to the calculation formula (4) shown below.

TQFINH = TQPCR x DPCR ... (4)

TQPCR: sensitivity coefficient

DPCR: amount of pressure change

The TQFINH correction value for the period of injection is a value for the correction of the TQFINB period of basic injection, in order to compensate for the discrepancy between the actual fuel injection amount and the QFIN amount of required injection resulting from the change in pressure of Fuel injection mentioned above.

Then, in step 700, ECU 60 calculates a final injection TQFIN period according to the formula of calculation (5) shown below.

TQFIN = TQFINB x TQFINH ... (5)

TQFINBT: basic injection period

TQFINH: correction value for the period of injection

Having calculated the period in this way TQFIN final injection, ECU 160 temporarily terminates the current sequence

The ECU 160 then produces a signal of performance for injectors 112 based on the TQFIN period of final injection, and outputs the signal for injectors 112 in the moment when the angle c of the crankshaft coincides with the instant Start fuel injection. As a result, the 112 injectors inject fuel in an amount equal to the QFIN amount of injection required.

As described so far, according to the fuel injection control of the present embodiment, the DPCR amount of pressure change during the APCR period of Pressure change estimate, estimated based on quantity QPUMP fuel pressure feed and quantity QLEAK fuel leak. The basic injection period TQFINB, which is corrected by the TQFINH correction value of the injection period based on the DPCR amount of change of pressure, is established as TQFIN period of final injection.

Consequently, if the injection pressure of fuel changes during the APCR change estimate period pressure due to fuel pressure feed or fuel leakage, even during stationary operation of the engine in which the detected value of the injection pressure of fuel (the actual PCR fuel pressure) just changes, the amount of change (the DPCR amount of pressure change) can be  accurately estimated based on the QPUMP amount of fuel pressure feed and QLEAK amount of leakage made out of fuel. In addition, the final injection TQFIN period may be set with extremely high precision as a value suitable to prevent the actual injection amount of fuel deviates from the amount of injection QFIN required in based on the DPCR amount of pressure change.

As a result, according to the present embodiment, it is possible to safely reflect the change in injection pressure of fuel with the fuel injection control if it has change occurred after real PCR pressure detection made out of fuel. Consequently, the injection control of fuel can be carried out with extremely precision high.

Especially because the QPUMP amount of fuel pressure feed as the QLEAK amount of Fuel leakage refer to the estimate of the DPCR amount pressure change, both the injection pressure rise of fuel resulting from the pressure feed of fuel as the fuel injection pressure drop resulting from fuel leakage, they can be reflected on the DPCR amount of pressure change. In Consequently, it is possible to prevent the actual injection amount of fuel becomes larger or smaller than the QFIN amount injection required due to such a rise or fall in pressure Fuel injection

As a result, it is possible to avoid production of any inconvenience such as the deterioration of the properties exhaust, resulting from the engine 110 that is powered by a excessive amount of fuel that is not suitable for that state Engine operation It is also possible to avoid the production of any inconvenience such as a decrease in the output of the engine, resulting from engine 110 that is not powered by a sufficient amount of fuel that is adequate for that state Engine operation

Third Realization

Now a third embodiment will be described of the present invention focused on the difference between the second and the third embodiment. Whatever construction similar to that of the second embodiment, it will not be described.

In the present embodiment, the calculation process TQFIN period of final injection is different from the second realization.

The process of calculating the TQFIN period of final injection is going to be described now with reference to the diagram of flow shown in Figure 13. Outside the respective stages 100 to 710, those indicated with the same reference numbers as in Figure 11 refer to the same processes that have been described in the foregoing. Therefore, the description of these stages will be omitted

Having carried out the processes of the stages 100, 200, the ECU 160 calculates, in the stage 400, a DPCR amount of pressure change. Then in the step 610, ECU 160 performs a correction by adding the amount DPCR pressure change to the actual fuel PCR pressure, and set a value thus corrected as the new real PCR pressure of fuel.

Then in step 710, as in the process of step 300 shown in Figure 9, ECU 160 calculates a final injection TQFIN period based on pressure Actual PCR of renewed fuel and QFIN injection quantity required, by reference to the functional data shown in Figure 11. After having calculated the TQFIN period of final injection, ECU 160 temporarily terminates the processes of this sequence

As described so far, according to the present embodiment, in order to prevent the amount of actual fuel injection deviate from the QFIN amount of required injection due to a change in the pressure of the fuel, the actual fuel pressure should only be corrected based on the DPCR amount of pressure change with prior to the calculation of the TQFIN period of final injection.

Consequently, there is no need to run risks to calculate the basic injection TQFINB period and the TQFINH value of the injection period correction. Neither there is a need to prepare functional data in advance to the calculation of the injection period correction TQFINH value as shown in figure 11, and the like. Thus, the structure of Global control can be simplified.

In the second embodiment and in the present embodiment, the DPCR amount of pressure change is estimated at base both the QPUMP amount of pressure feed of fuel as to the QLEAK amount of fuel leakage. Without However, the DPCR amount of pressure change can be estimated also based only on the QPUMP amount of feed to fuel pressure or only the QLEAK amount of leakage from fuel.

Quarter Realization

Now a fourth embodiment of the present invention focused on the difference between the second and The fourth embodiment.

In the present embodiment, a control apparatus fuel injection according to the present invention, is applied to the 110 engine, capable of carrying out the pilot injection. As is known, this pilot injection is intended to prevent a sharp increase in combustion pressure through preliminary injection of a small amount of fuel with prior to the main injection, and to reduce the combustion noise level. According to the injection control of fuel of the present embodiment, if the injection pressure of fuel drops due to pilot injection, the period of injection at the time of the main injection (the period TQMAIN main injection) is corrected up to a period appropriate based on the amount of pressure decrease.

In the present embodiment, the instants of opening of the respective valves 170a, 170b of adjustment is set in advance, so that the power to fuel pressure by means of the fuel pump 130 is always start after the end of the main injection (see figure 16). Therefore, there is no possibility that the fuel pressure feeding could be carried out during the period between the actual PCR pressure of fuel and completion of the main injection, or that the  fuel injection pressure could change due to the fuel pressure feed.

Now it will be described in what follows the Calculation process of a TQMAIN period of main injection.

Figures 14 and 15 are flow charts that show calculation processes of a TQMAIN injection period Main and one-period TQPLT pilot injection. Figure 16 it is a time diagram that shows the suction moments of fuel to, and fuel pressure feed from, the respective pumps 150a, 150b supply, and a change pattern of fuel injection pressure caused by pilot injection, main injection, and the like.

The ECU 60 carries out a series of processes in the respective flow charts of figures 14 and 15, as interruption handling, at crankshaft angle intervals default (180º AC). As is the case with the sequences of processing shown in figures 9 and 13, the instant for interruption of the present sequence is set instantly in which the respective feed pumps 50a, 50b are commutated from an admission race to a career pressure feed (the instant the AC angle of the crankshaft reaches angles CA0, CA1, CA2 and CA3 shown in the figure 16).

The ECU 60 detects a real PCR pressure of fuel in stages 100, 200 of figure 14, and calculates In addition a QFIN amount of injection required based on grade ACCP throttle opening, at engine rotational speed, and similar.

In step 320, ECU 60 calculates an amount QPLT pilot injection based on the rotational NE speed of the engine and QFIN amount of injection required. The QPLT amount of pilot injection in relation to the rotational NE speed of the engine and the amount of injection QFIN required, is calculated from preliminary form through experiments and the like, in order to better adapt it to the operating state of the engine in consideration of combustion noise, at the concentration of exhaust gas and similar, and is stored in memory 64 as functional data for the calculation of the quantity of pilot injection QPLT.

Next, in step 330, a QMAIN amount of main injection according to the calculation formula (6) shown below.

QMAIN = QFIN - QPLT ... (6)

QFIN: amount of injection required

QPLT: amount of pilot injection.

After having calculated in this way the QPLT amount of pilot injection and QMAIN amount of injection principal, the ECU 60 calculates, in step 450, the amount of change of fuel injection pressure (an amount DPCRPLT pressure change) during the period from real fuel PCR pressure detection until the start of pilot injection (an APCRPLT period of change estimate of pressure: see Figure 16), and the amount of change in pressure fuel injection (a DPCMAINR amount of change of pressure) during the period from the pressure detection Actual fuel PCR until the start of the main injection (an APCRMAIN period of pressure change estimate: see figure 16).

Figure 15 is a flow chart showing in detail the process of calculating the respective amounts of pressure change DPCRPLT, DPCRMAIN.

In step 452, ECU 160 converts the respective periods of APCRPLT pressure change estimate, APCRMAIN in times based on the rotational NE speed of the engine, and set the converted values as a TLEAKPLT period of fuel leakage from the actual PCR pressure detection of fuel until the start of the pilot injection, and period of TLEAKMAIN fuel leakage from PCR pressure detection actual fuel until the start of the main injection, respectively.

As in the processing stage 408 of Figure 10, ECU 160 calculates, in step 454, the amount of fuel leakage (a QLEAKPLT amount of fuel leakage) from the detection of the actual PCR fuel pressure to the start of pilot injection, and the amount of fuel leakage (a QLEAKMAIN amount of fuel leakage) since detection of the actual PCR fuel pressure until the start of the main injection, based on the respective TLEAKPLT periods, TLEAKMAIN fuel leakage, the actual PCR pressure of fuel, and the fuel THF temperature. In addition, like that in processing step 410 shown in Figure 10, the ECU 160 calculates, in step 456, an elasticity coefficient E of volume based on the actual fuel PCR pressure and the THF fuel temperature.

Then, in step 458, ECU 60 calculates the respective amounts DPCRPLT, DPCRMAIN change pressure, according to calculation formulas (7) and (8) shown at continuation.

DPCRPLT = QLEAKPLT / VCR ... (7)

\hbox{QLEAKMAIN)/}

VCR ... (8)DPCRMAIN = E x (QPLT +

 \ hbox {QLEAKMAIN) /} 

VCR ... (8)

E: volume elasticity coefficient

QLEAKPLT, QLEAKMAIN: leakage amounts of fuel

VCR: common rail volume 20

As is evident from the formula of calculation (8), in addition to the QLEAKMAIN amount of leakage of fuel, the amount of pilot injection QPLT is reflected also in the calculation of the DPCRMAIN amount of pressure change from the detection of the actual PCR fuel pressure to the start of the main injection. This is because with the realization of the pilot injection, the main injection is carried conducted at a fuel injection pressure that is less than that of the pilot injection.

After having calculated the respective Pressure change amounts DPCRPL, DPCRMAIN, ECU 60 move the process to step 620 shown in figure 14. In the step 620, the ECU 60 calculates a fuel injection pressure at the start of the pilot PCRPLT injection (cited in What follows as "injection fuel pressure pilot ") and a fuel injection pressure at the time of initiation of the main PCRMAIN injection (cited below as "main injection fuel pressure"), according to the calculation formulas (9) and (10) shown in what follow, respectively.

PCRPLT = PCR - DPCRPLT ... (9)

PCRMAIN = PCR - DPCRMAIN ... (10)

PCR: actual fuel pressure

DPCRPLT, DPCRMAIN: exchange amounts of Pressure.

As evident from these formulas Calculation (9) and (10), both injection fuel pressure PCRPLT pilot as the injection fuel pressure PCRMAIN Main are obtained by correcting the actual fuel PCR pressure based on the respective amounts of DPCRPLT pressure change and DPCRMAIN, respectively.

Then in step 720, as in the process of step 710 shown in figure 13, ECU 60 calculates a pilot TQPLT injection period and a period of main TQMAIN injection based on the respective pressures of PCRPLT fuel, PCRMAIN, the amount of pilot injection QPLT and QMAIN amount of main injection, with reference to the data function shown in Figure 11. As a result, the periods of respective injection TQPLT, TQMAIN are substantially corrected based on the respective fuel pressures PCRPLT, PCRMAIN mentioned above.

After having calculated the respective injection periods TQPLT, TQMAIN, the ECU 60 ends Temporarily processes the current sequence.

As described so far, according to the present embodiment, the TQPLT period of pilot injection and the TQMAIN period of main injection are corrected based on the fuel pressure changes since the detection of actual PCR fuel pressure until the start of the injection pilot or the main injection (the amounts of change of DPCRPLT pressure, DPCRMAIN).

Consequently, the respective periods of TQPLT injection, TQMAIN can be set accurately extremely high as adequate values to prevent actual amounts of fuel injection during injection pilot and the main injection deviate from the QPLT amount of pilot injection and the amount of QMAIN main injection, respectively. Even if the injection is done pilot, fuel injection control can be carried out with extremely high accuracy.

In addition, the pressure reduction amounts of fuel injection resulting from fuel leakage (the Pressure change amounts DPCRPLT, DPCRMAIN) are estimated to be safely, and the respective injection periods TQPLT, TQMAIN are corrected based on the amounts of pressure reduction Fuel injection With this, it is possible to prevent the actual fuel injection amounts during the pilot injection and main injection, become smaller than the QPLT amount of pilot injection and the QMAIN amount of main injection as required injection amounts. How result, it is possible to avoid the production of such an inconvenience as a reduction in engine output, resulting from the engine, in its internal concentration, is not being fed with a sufficient amount of fuel that fits the state Engine operation

Especially, when the quantity is estimated DPCRMAIN pressure change from PCR pressure detection actual fuel until the start of the main injection, the amount of fuel injection pressure reduction resulting from the injection of the pilot injection, as well as of the fuel leak, it is taken into consideration. So, it turns out possible to prevent fuel injection pressure from falling due to the implementation of the pilot injection, and prevent the actual fuel injection amount during injection Main become smaller than the QMAIN injection quantity principal. Consequently, in this sense, it is possible to avoid more reliably producing some inconvenience such as the motor output reduction.

In the present embodiment, the amount DPCRMAIN of pressure change from the actual PCR pressure detection of fuel until the start of the main injection is estimated at based on the QLEAKMAIN amount of fuel leakage and the amount QPLT pilot injection. However, the DPCRMAIN amount of pressure change can be estimated based only on the QLEAKMAIN amount of fuel leakage or the QPLT amount of pilot injection However, the DPCRMAIN amount of change of pressure can also be estimated based on quantity only QLEAKMAIN fuel leakage or QPLT injection quantity pilot.

In addition, in case of a construction in which the Fuel pressure feeding can be started with prior to the start of the main injection, you can calculate a fuel pressure feed amount from the actual PCR fuel pressure detection until the start of the main injection. The DPCRMAIN amount of change of pressure can be estimated based on the amount of feed to fuel pressure or the amount of QPLT pilot injection, as well as the QLEAKMAIN amount of fuel leakage.

In addition, in the present embodiment, the pressure Actual fuel PCR is previously corrected based on the respective amounts of pressure change DPCRPLT, DPCRMAIN, and fuel injection periods during pilot injection and the main injection (the TQPLT period of pilot injection, the PCRMAIN period of main injection) are calculated based on the values after said correction (the PCRPLT pressure of Pilot injection fuel, PCRMAIN fuel pressure main injection). However, as in the second realization, correction values in relation to the period TQPLT pilot injection and with the injection TQMAIN period Main can be calculated based on the respective pressure change amounts DPCRPLT, DPCRMAIN, and the respective  Fuel injection periods TQPLT, TQMAIN can be corrected based on these correction values.

In addition, in the embodiment mentioned in what above, an example is shown in which the pilot injection is perform only once before injection principal. However, pilot injection can be carried out. a plurality of times before the main injection. In that case, after the pilot injection has been performed more than once, the next pilot injection is done in such a way that the fuel injection period during that injection pilot is corrected based on a change in the injection pressure of fuel that is estimated based on the total amount of injection of fuel during the pilot injection performed previously.

Fifth Realization

A fifth embodiment of the present invention is going to be described now, focusing on the difference between the Second and fifth embodiment.

In the present embodiment, in addition to the change of the fuel injection pressure during the APCR period of pressure change estimate, pressure change is estimated fuel injection resulting from the pressure feed of fuel or fuel leakage. The TQFIN period of final injection is also corrected based on the change in pressure fuel injection, which further increases the precision of fuel injection control.

The process of estimating a change in the fuel injection pressure during such period of fuel injection and period correction process TQFIN final injection based on a change in the pressure of fuel injection, will now be described in what follow.

Figure 17 is a flow chart showing a process of estimating a change in the injection pressure of fuel during the fuel injection period (cited in what follows as "DPCINJ amount of pressure change"). The respective processes shown in this flowchart, are carried out following the processing in step 412, as part of a series of prosecutions shown in the diagram of flow of figure 10.

First, in step 420, ECU 160 add the actual PCR fuel pressure to the DPCR amount of pressure change calculated by the process of step 412. In based on the sum (PCR + DPCR) and the fuel THF temperature, ECU 160 calculates again an elasticity coefficient E of volume such that the volume elasticity coefficient E corresponds to a value at the start of the injection of fuel.

Then, in step 422, the amount QLEAKINJ fuel leak during the injection period of fuel, is calculated based on the TQFINB injection period Basic and THF fuel temperature. Then in the step 424, it is determined whether the instant for the start of the fuel pressure supply from pump 30 of fuel, has advanced ahead of time for the start of fuel injection, in particular, if the Fuel pressure feeding is carried out or not with prior to the start of fuel injection. Whether determines that the fuel pressure feed is brought to carried out before the start of the fuel injection, the fuel is always fed under pressure during the period of fuel injection Therefore, in step 426, ECU 60 converts the basic injection period TQFINB into an AC angle of the crankshaft based on engine rotational NE speed, and sets the value converted as APUMPINJ period of pressure feed during the period of fuel injection.

Next, in step 428, a QPUMPINJ amount of fuel pressure feed during the fuel injection period, according to a formula of calculation (11) shown below.

QPUMPINJ = APUMPINJ x KQPUMP ... (11)

APUMPINJ: pressure feeding period

KQPUMP: pressure feed ratio of fuel.

On the other hand, if it is determined in step 424 that fuel pressure feeding is not carried out with prior to the start of fuel injection, ECU 60 change processes to stage 430. In stage 430, ECU 60 calculates a period of completion of fuel injection based on the start time of the fuel injection, at TQFINB instant of basic injection, and at rotational NE speed of the engine, using the crank angle CA as a Unit.

In the next step 432, comparing the period end of fuel injection with the instant of Start of fuel pressure feeding from the pump 30 fuel, it is determined whether the pressure feed of fuel is started or not during the injection period of fuel. If it is determined here that the pressure feed of fuel is started during the injection period of fuel, a period is calculated in step 434 (AC angle of crankshaft) from the moment of fuel pressure feeding until the fuel injection termination period, such as APUMPINJ period of pressure feeding, during the period of fuel injection Then, in step 436, you calculates a QPUMPINJ amount of pressure feed of fuel during the fuel injection period, according to the calculation formula (11) mentioned above.

On the other hand, if it is determined in step 432 that the fuel pressure feed has not started during the period of fuel injection, the period of Pressure feed does not overlap with the injection period of fuel. Thus, in step 435, ECU 60 establishes the QPUMPINJ amount of fuel pressure feed during the fuel injection period as zero.

Once you have carried out any of the stages 428, 435 and 486 mentioned above, ECU 60 calculates, in step 440, a DPCRINJ amount of pressure change during the fuel injection period according to the calculation formula (12) shown below.

DPCERINJ = E x (QPUMPINJ - QLEAKINJ) / VCR ... (12)

E: volume elasticity coefficient

QPUMPINJ: amount of pressure feed of fuel during the fuel injection period

QLEAKINJ: amount of fuel leakage during the fuel injection period

VCR: volume of common lane 20.

Then, in step 442, ECU 60 calculates an average DPCRAVE amount of pressure change based on the DPCR amount of pressure change already calculated during the pressure change estimation period, and the DPCRINJ amount of pressure change during the fuel injection period mentioned above, according to the calculation formula (13) that show below.

DPCRAVE = DPCR + DPCRINJ / 2 ... (13)

The average DPCRAVE amount of pressure change is the average value of the DPCR amount of pressure change from the real fuel PCR pressure detection until the start of fuel injection (that is, during the APCR period of pressure change estimate), and the amount of change of pressure change (DPCR + DPCRINJ) from pressure detection Actual fuel PCR until the end of the injection of fuel.

Once the average DPCRAVE amount of change pressure has been calculated in this way, the processes that follow in step 500 shown in figure 9. In this case, with the processing in step 600, a value is calculated TQFINH correction of injection period based on quantity DPCRAVE average pressure change mentioned above, in place of the DPCR amount of pressure change during the period APCR pressure change estimate. With it, in the following step 700, the TQFINB period of basic injection in base is corrected at the change in fuel injection pressure (the amount DPCRINJ pressure change) during the injection period of fuel, as well as the change in injection pressure of fuel (DPCR amount of pressure change) during APCR period of pressure change estimate.

Thus, according to the present embodiment, it turns out possible not only prevent the actual injection amount of fuel deviates from the amount of injection QFIN required due to a change in fuel injection pressure from the actual PCR fuel pressure detection until the start of fuel injection, but also to prevent the deviation of the resulting fuel injection amount from a change in fuel injection pressure during the fuel injection period. As a result, the control Fuel injection can be carried out with a much higher accuracy.

In particular, when the amount of change in fuel injection pressure during the period fuel injection (the DPCRINJ amount of change of pressure), the amount of pressure feed QPUMP is mentioned of fuel and the QLEAK amount of fuel leakage. So, both the amount of increase in the injection pressure of fuel resulting from the fuel pressure feed as the amount of a drop in the injection pressure of fuel resulting from fuel leakage, can be reflected in the DPRCINJ amount of pressure change. In Consequently, it is possible to prevent the actual injection amount of fuel becomes greater than the QFIN amount of injection required, due to an elevation of the injection pressure of fuel, or conversely, prevent the amount of actual fuel injection becomes less than the amount Injection QFIN required due to a drop in pressure of fuel injection As a result, it is possible to avoid production of any inconvenience such as the deterioration of exhaust properties, which would result from the fact that the engine 110 be fed with an excessive amount of fuel other than suitable for the operating state of the engine. It is also possible avoid the production of any inconvenience such as a decrease  engine output, which would result from the fact that the engine 110 is not fed with a sufficient amount that fits the engine operating status

In the present embodiment, the amount DPRCINJ pressure change during the fuel injection period It is estimated based on the QPUMPINJ amount of pressure feed of fuel and the QLEAKINJ amount of fuel leakage. Without However, the DPCRINJ amount of pressure change can be estimated based only on the QPUMPINJ amount of feed to fuel pressure or only the QLEAKINJ amount of leakage made out of fuel.

In the second to fourth embodiments, like that in the present embodiment, the amount of change in fuel injection pressure resulting from the fuel pressure or fuel leakage during the pilot injection period or the injection period main, and the TQPLT period of pilot injection and the period TQMAIN main injection can also be corrected based to the amount of change thus estimated in the injection pressure of fuel.

In addition, in the second, third and fifth mentioned above, the amount of feed to Fuel pressure of the fuel pump 30 is calculated in function of the assumption that the feed rate to Fuel pressure (KQPUMP) be constant. However, by example, even in the case that the feed rate to fuel pressure change depending on the start instant of the fuel pressure feed, the amount of Fuel pressure feed can be calculated with reference to a map or similar that shows the proportion of fuel pressure supply in relation to the instant of Start of fuel pressure feed.

In the second to fifth embodiments mentioned In the above, an example is shown in which the amount of Fuel injection is controlled based on a period of fuel injection, particularly, at an opening period valve nozzles 112. However, for example, the fuel injection amount can be controlled based not only to the valve opening period but also to the degree of opening of the injectors 112. In this case, it may be possible correct a command value for the degree of opening of the 112 injectors based on a change in the injection pressure of fuel.

In the second to fifth embodiments discussed In the above, a diesel engine has been represented as an example internal combustion engine to which the appliance is applied fuel injection control of the present invention. Without However, for example, the present invention can be applied also to a direct injection gasoline engine, in which the fuel is injected directly into the chambers of combustion.

Claims (22)

1. Accumulator fuel injection control apparatus, characterized in that it comprises: detection means (14) for detecting a fuel pressure in an accumulator line (4); means (22) of estimation to estimate a fuel pressure injected into an engine (1); means (21) for calculating the amount of control fuel injection, to calculate a control amount fuel injection based on fuel pressure detected or at estimated fuel pressure; Y fuel injection means to inject fuel in the engine based on the amount of control of calculated fuel injection, in which: the means (21) for calculating the amount of fuel injection control determine which of the fuel pressure detected and fuel pressure estimated to be used, based on the instant injection of fuel injection media. 2. Accumulator fuel injection control apparatus according to claim 1, characterized in that: the detection means (14) detect a pressure of fuel at first (t1); means (2) of fuel injection they inject fuel in a second instant (t2) that is later at the first moment; Y The means (21) for calculating the amount of injection control calculate the amount of fuel injection control based on the detected fuel pressure, if the arithmetic processing of the fuel pressure detected in the first instant is completed previously to the second

 \ hbox {instant.} 

3. Accumulator fuel injection control apparatus according to claim 2, characterized in that: the means (21) for calculating the amount of fuel injection control determine which of the fuel pressure detected and fuel pressure estimated to be used, based on a first time (T1) that goes from the first instant (t1) until the second instant (t2), and at a second time (T2) required for arithmetic processing. 4. Accumulator fuel injection control apparatus according to claim 3, characterized in that: the means (21) for calculating the amount of fuel injection control calculate the amount of control fuel injection using fuel pressure detected, if the first time (T1) is longer than the second time (T2). 5. Accumulator fuel injection control apparatus according to claim 1, characterized in that: the means (21) for calculating the amount of fuel injection control determine which of the fuel pressure detected and fuel pressure estimated must be used to calculate the amount of control of fuel injection, based on the rotational speed of the engine (1). 6. Accumulator fuel injection control apparatus according to claim 5, characterized in that: the means (21) for calculating the amount of fuel injection control calculate the amount of control fuel injection using fuel pressure detected, if the rotational speed of the motor (1) is less than a default value. 7. Accumulator fuel injection control apparatus according to claim 1, characterized in that: the estimation means (22) calculate the pressure of fuel based on the operational state of a pump (7) for the supply of fuel to the accumulator duct (14), and to a coefficient of elasticity of fuel volume. 8. Accumulator fuel injection control apparatus according to claims 1 to 7, characterized in that: the amount of injection control of Fuel is an amount of fuel injection. 9. Accumulator fuel injection control apparatus according to claim 1, characterized in that: estimation means (22) estimate the pressure of fuel based on the amount of pressure feed of fuel by means of the pump (7) for the supply of fuel to the accumulator duct (14) for a period that goes from the detection of the fuel pressure to the beginning of fuel injection 10. Accumulator fuel injection control apparatus according to claim 1, characterized in that: estimation means (22) estimate the pressure of fuel based on an amount of fuel leakage from the duct (14) of the accumulator. 11. Accumulator fuel injection control apparatus according to claims 1 to 10, characterized in that: estimation means (22) estimate the pressure of fuel based on a change in fuel pressure during a period of fuel injection. 12. Method for controlling a fuel injection, characterized by the steps of: detect a fuel pressure in a accumulator duct (4); estimate a fuel injected pressure in a motor (1); calculate an injection control amount of fuel based on the fuel pressure detected or the estimated fuel pressure; and inject fuel into the engine based on the amount of fuel injection control calculated, with the additional stage of: determine which of the pressure of fuel detected and the estimated fuel pressure must be used, based on the instant fuel injection of the means of injection. 13. Method according to claim 12, characterized by: detect a fuel pressure in a first instant (t1); inject fuel in a second instant (t2) which is after the first instant; Y calculate the amount of injection control of fuel based on the fuel pressure detected, if completed an arithmetic fuel pressure processing detected in the first instant before the second instant. 14. Method according to claim 13, characterized by: determine which of the pressure of fuel detected and the estimated fuel pressure must be used, based on a first time (T1) that goes from the first instant (t1) until the second instant (t2), and a second time (T2) required for arithmetic processing. 15. Method according to claim 14, characterized by: calculate the amount of injection control of fuel using the fuel pressure detected, if the First half (T1) is longer than the second half (T2). 16. Method according to claim 12, characterized by: determine which of the pressure of fuel detected and the estimated fuel pressure must be used to calculate the amount of injection control of fuel, based on the rotational speed of the engine (1). 17. Method according to claim 16, characterized by: calculate the amount of injection control of fuel using the fuel pressure detected, if the motor rotational speed (1) is less than a value predetermined. 18. Method according to claim 12, characterized by: calculate the fuel pressure based on a operational status of a pump (7) for fuel supply to an accumulator duct (14), and at an elasticity coefficient of fuel volume. 19. Method according to claims 12 to 18, characterized in that: the amount of injection control of Fuel is an amount of fuel injection. 20. Method according to claim 12, characterized by: estimate the fuel pressure based on a amount of fuel pressure feed by means of a pump (7) for fuel supply to the duct (14) of accumulator for a period ranging from the detection of the fuel pressure until the start of the injection of fuel. 21. Method according to claim 12, characterized by: estimate the fuel pressure based on a amount of fuel leakage from the duct (14) of accumulator. 22. Method according to claims 12 to 21, characterized by: estimate a fuel pressure based on a change in fuel pressure over a period of fuel injection