DE69827552T2 - Fuel pressure control device for a fuel injection system of an internal combustion engine - Google Patents

Description

BACKGROUND THE INVENTION

The The present invention relates to fuel injection systems for machines, which temporarily store fuel under high pressure in an accumulator and inject the fuel into combustion chambers. special The present invention relates to a fuel pressure control apparatus for optimization the fuel pressure in the accumulator.

The unaudited Japanese Patent Publication No. 7-103095 discloses a fuel injection system. The system contains a common pipe or pipe or an accumulator with a high-pressure pump is connected. The common pipe or pipe is called "Common Rail "on the present Area known. The common rail is with injectors from the connected electromagnetic valve type. The pressure in the common Rail is detected by means of a pressure sensor. The high pressure pump and the injectors are controlled by an electronic control unit ECU controlled. When the machine is started, the High-pressure pump fuel to the common rail to, which in turn temporarily stores the fuel under high pressure. When the ECU opens the injectors, it will Fuel with the same pressure as the fuel in the common Rail injected into the combustion chambers of the machine.

The ECU optimizes the fuel pressure in the common rail or the injection pressure the injection device based on the running state of the machine and the fuel injection amount. Specifically, the ECU calculates a Setpoint of the fuel pressure in the common rail based on the machine running condition. The ECU generally increases the setpoint, if a bigger load acts on the machine. When the fuel pressure in the common rail, which is detected by means of the pressure sensor, is lower as the target value, the ECU controls the high-pressure pump to adjust the fuel injection amount to increase, which fed to the common rail becomes. When the fuel pressure in the common rail is greater than the setpoint, the ECU regulates the high pressure pump to the amount of To reduce fuel that is supplied to the common rail.

If the key switch is turned off, the high pressure pump simultaneously stops feeding the Fuel to the common rail. Even if therefore the injectors open remain (due to a malfunction), the fuel pressure falls in the common rail decreases rapidly when the key switch is turned off and fuel injection from injectors is stopped off. It thus becomes an undesirable fuel injection prevented after the key switch was turned off.

If the key switch has been turned off, the fuel pressure in the common rail during the subsequent non-operating state of the machine up so long received when no malfunction of the injectors occurs. If the machine is restarted, fuel will be below the same Injected pressure that was present when the key switch was turned off. Therefore, the injection pressure that varies for disposal is very pronounced when the machine is started, depending on Running state of the machine, if the key switch earlier was turned off. This causes the following disadvantages.

If for example, the key switch immediately, after the fuel pressure in the common rail has been lowered, is turned off, the fuel pressure is insufficient when the Machine is restarted. As a result, the fuel injection becomes not started until the fuel pressure in the common rail up a sufficiently high value has risen to start the machine can. Even if the fuel injection is started, the Fuel pressure should not be high enough to get enough fuel into the combustion chambers. In this case, the atomization fuel insufficient. This delays the starting process of the machine.

On the other side there are cases where the fuel pressure in the common rail kept relatively high becomes. For example, the fuel pressure in the common rail held high when the machine is spinning or immediately after the Machine stops, to spin. The "racing" of the machine called a high engine speed when on the machine substantially no load is acting.

If a machine is spinning, the fuel pressure in the common takes Rail to and the amount of fuel injection is increased. If hence the key switch is turned off while the machine is spinning or immediately after the machine has gone through has, the fuel pressure in the common rail is kept too high. Therefore, the fuel pressure in the common rail is also higher than the value that is suitable for starting the machine.

When the fuel injection is started at a pressure higher than the proper pressure when the engine is started, the fuel for starting the engine is excessively atomized. This causes the ignition pressure in the combustion chambers to be suddenly changed, thereby Noises arise.

SUMMARY THE INVENTION

It It is therefore an object of the present invention to provide a fuel pressure control apparatus for fuel injection systems to create, which improves the starting of a machine.

Around to solve the above problem the present invention, an apparatus for controlling the fuel pressure in a machine. The device comprises an accumulator for storage of high-pressure fuel coming from a pump supplied from is an injection device for injecting the fuel, which is stored in the accumulator, in a combustion chamber the machine, and an adjusting device for adjusting the fuel pressure in the accumulator in accordance with the running state of the machine. When the running state of the machine reaches a certain state, the adjuster makes the fuel pressure in the accumulator so to get a desired value to approach, the for a subsequent restart of the machine is suitable, regardless the fuel pressure corresponding to the particular state.

Other Aspects and advantages of the invention will become apparent from the following Description in conjunction with the attached drawings, which are based on an example illustrating the principles of the invention.

SHORT DESCRIPTION THE DRAWINGS

The Invention, together with objects and advantages thereof, may be Best referring to the following description of the moment preferred embodiments in conjunction with the attached Drawings are understood.

1 FIG. 10 is a cross-sectional view illustrating a fuel pressure control apparatus in a fuel injection system according to a first embodiment of the present invention; FIG.

2 FIG. 12 is a graph showing changes in a basic fuel injection amount based on a relationship between the engine speed and the degree of depression of the accelerator pedal; FIG.

3 FIG. 10 is a graph illustrating changes in a target fuel pressure based on the relationship between the engine speed and a basic fuel injection amount; FIG.

4 Fig. 11 is a timing chart showing changes in the state of a pressure control valve (PCV), as well as the amount of fuel discharge from a supply pump and the valve lift of a plunger;

5 FIG. 10 is a flowchart showing a fuel pressure control routine according to the first embodiment; FIG.

6 Fig. 10 is a graph showing the relationship between a coolant temperature and a commanded fuel pressure;

7 Fig. 12 is a graph showing the relationship between the engine speed when the key switch is turned off and a feedback coefficient;

8th shows a timing chart illustrating changes in the fuel pressure when a key switch is turned off;

9 FIG. 12 is a flow chart showing a fuel pressure control routine in accordance with a second embodiment of the present invention; FIG.

10 FIG. 12 is a graph illustrating the relationship between engine speed when the key switch is turned off and fuel injection continuation time associated with a third embodiment; FIG.

11 FIG. 10 is a flowchart showing a fuel pressure control routine according to the third embodiment of the present invention; FIG.

12 FIG. 12 is a timing chart showing changes in engine speed when the key switch is turned off in connection with the third embodiment; FIG.

13 Fig. 12 is a timing chart showing changes in the fuel pressure when the key switch is turned off in the third embodiment;

14 Fig. 10 is a flowchart showing a fuel pressure control routine according to a fourth embodiment of the present invention;

15 FIG. 10 is a flowchart showing a routine for calculating a target fuel pressure according to a fifth embodiment of the present invention; FIG.

16 is a graph showing the relationship between to illustrate the engine speed and a maximum target fuel pressure according to the fifth embodiment;

17 shows a timing chart representing changes in the fuel pressure when the engine is spinning, according to the fifth embodiment;

18 Fig. 10 is a flow chart showing a routine for calculating a target fuel pressure in accordance with a sixth embodiment of the present invention;

19 FIG. 15 is a graph showing the relationship between the engine speed and a maximum basic fuel injection amount according to the sixth embodiment; FIG.

20 FIG. 12 is a timing chart illustrating changes in the fuel pressure when the engine is spinning, in accordance with the sixth embodiment; FIG.

21 Fig. 10 is a flow chart showing a routine for compensating the degree of depression of the accelerator pedal according to a seventh embodiment of the present invention;

22 Fig. 10 is a graph illustrating the relationship between the engine speed and a maximum degree of depression of the accelerator pedal according to the seventh embodiment;

23 FIG. 10 is a cross-sectional view showing a fuel pressure control apparatus in a fuel injection system according to an eighth embodiment of the present invention; FIG.

24 FIG. 10 is a flowchart illustrating a routine for controlling the fuel pressure according to the eighth embodiment; FIG.

25 Fig. 11 is a timing chart showing changes in the fuel pressure during a non-operating state of an engine according to the eighth embodiment;

26 FIG. 10 is a cross-sectional view illustrating a fuel pressure control apparatus in a fuel injection system according to a ninth embodiment of the present invention; FIG.

27 FIG. 10 is a flow chart showing a routine for controlling a relief valve according to the ninth embodiment; FIG.

28 FIG. 14 is a timing chart showing changes in the fuel pressure in relation to the state of a starter signal in the embodiment of FIG 27 reproduces;

29 FIG. 10 is a flowchart showing a routine for controlling the fuel pressure according to a tenth embodiment of the present invention; FIG.

30 FIG. 12 is a graph showing the relationship between the coolant temperature and the withstand time in the embodiment of FIG 29 illustrated; and

31 FIG. 11 is a timing chart showing changes in fuel pressure in relation to the state of a starter signal in the embodiment of FIG 29 reproduces.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

A first embodiment of a fuel pressure control apparatus according to the present invention will be described below with reference to FIGS 1 - 8th described. The device is used in a fuel injection system of a diesel engine 1 used. As in 1 shown is the diesel engine 1 used in a vehicle and contains four # 1 - # 4 cylinders. The diesel engine 1 owns injectors 2 each of which corresponds to a combustion chamber of one of cylinders # 1- # 4. Every injector 2 injects fuel into the associated combustion chamber and contains an electromagnetic valve 3 for injecting the fuel. The amount and timing of the fuel injection from each injector is made by opening and closing the corresponding valve 3 controlled.

Injectors 2 are with an accumulator or a common rail 4 connected. The common rail 4 is with an outlet opening 6a a feed pump 6 via a feed tube 5 connected. A check valve 7 is in the feed tube 5 located. The check valve 7 prevents fuel to the feed pump 6 can flow back from the common rail 4 out. The feed pump 6 has a suction port 6b and a return port 6c , The intake opening 6b is with fuel tank 8th over a filter 9 connected, and the return opening 6c is with the fuel tank 8th via a return pipe 11 connected.

Every injector 2 contains a return opening 3a in the neighborhood of its electromagnetic valve 3 is located. The return opening 3a is with the fuel tank 8th via the return line 11 connected. Part of the Fuel, of each injector 2 from the common rail 4 from being fed into the injectors 2 when the injector 2 opens and closes. The leaking fuel becomes the fuel tank 8th from the return opening 3a via the return pipe 11 returned.

The supply pump 6 has a piston and a pressure generating chamber (both are not shown). The piston runs synchronously with the rotation of a crankshaft (not shown) of the engine 1 back and forth. The fuel becomes the pressure generating chamber of the fuel tank 8th supplied. The pump 6 then pressurize the fuel with the aid of the piston. The pressurized fuel becomes the common rail 4 via an outlet opening 6a Posted. A pressure control valve (PCV) 10 is in the neighborhood of the outlet 6a located. The PCV valve 10 Regulates the fuel pressure coming from the exhaust port 6a is discharged. The supply pump 6 includes a feed pump that supplies fuel to the pressure generating chamber from the fuel tank 8th feeds.

The combustion chamber of each cylinder # 1- # 4 is with an intake port 13 and an outlet channel 14 connected. A throttle valve (not shown) is in the intake or intake passage 13 located. The throttle valve controls the opening process of the intake passage 13 in accordance with the degree of depression of the accelerator pedal 15 , whereby then the amount of air is supplied, which is supplied to the combustion chamber.

A glow plug 16 is arranged in such a manner that its distal end is located in the combustion chamber. The glow plug 16 is heated by electric current passing through a glow plug relay 16a is fed, and immediately before the machine 1 is started. It becomes fuel from the injector 2 out to the heated glow plug 16 sprayed. This promotes the ignition process and the combustion of the fuel.

The machine 1 Also contains a variety of sensors for detecting their running state. An accelerator pedal sensor 20 is near the gas pedal 15 located to the degree of depression (ACCP) of the pedal 15 to detect. A coolant temperature sensor 21 is in the cylinder block of the diesel engine 1 located to detect the temperature THW of the coolant in the cylinder block. A fuel pressure sensor 22 is in the common rail 4 located to the pressure PC of the fuel in the common rail 4 to detect. A fuel temperature sensor 23 is in the return line 11 located to detect the temperature THF of the fuel. Further, an inlet pressure sensor 24 in the intake channel 13 located to the pressure PM of the intake air in the channel 13 to detect.

A cranking sensor 25 is in the neighborhood of the crankshaft of the machine 1 located. A cam sensor 26 is disposed in the vicinity of a camshaft (not shown) that rotates in synchronization with the crankshaft. The crank sensor 25 and the cam sensor 26 detect the number of revolutions of the camshaft per unit time (engine speed NE) and the rotation angle of the crankshaft (crankshaft angle CA). A transmission (not shown) is coupled to the camshaft. A vehicle speed sensor 27 is located in the vicinity of the transmission to detect the vehicle speed (SPD).

Signals from the sensors 20 - 27 be an electronic control unit (ECU) of the machine 1 fed. The ECU 50 includes a central processing unit (CPU), a memory, an input-output circuit and a drive circuit (none of which is shown separately). The ECU 50 is with a battery 53 via a main relay 51 and a key switch 52 connected.

The main relay 51 contains a switch 51a and a winding 51b for opening and closing the switch 51a , The ECU 50 controls the main relay 51 based on the ON / OFF state of the key switch 52 to the supply of electricity to the ECU 50 to start and stop.

The ECU 50 energizes the winding 51b of the main relay 51 when the key switch 52 is turned on. As a result, the switch 51a closed and it becomes electricity of the ECU 50 from the battery 53 supplied from. On the other hand, the ECU is de-energized 50 the winding 51b when a predetermined period of time has elapsed after the key switch 52 was turned off. As a result, the switch 51a opened when the predetermined period of time has elapsed, after the key switch 51 was turned off. This stops the power from the battery 53 to the ECU 50 ,

It will be electricity of the ECU 50 supplied for a predetermined period of time after the key switch 52 turned it to the ECU 50 to allow control programs to be executed to stop the machine 1 , and to write results of malfunction detection in their memory.

The machine 1 has a starter 19 and a starter switch 19a , The starter switch 19a detects that the starter 19 was pressed. The key switch 52 is moved between the OFF position, the ON position and a start position. When the machine 1 is started, the key switch 52 moved from the OFF position to the start position over the ON position. The starter switch 19a gives a starter signal STA to the ECU 50 only when the starter 19 is operated, that is, when the machine is cranked. When cranking the machine 8th has been completed (if the machine 1 starts to run), becomes the key switch 52 moved back to the ON position from the starting position.

The ECU 50 receives information indicating the running state of the diesel engine 1 reproduce based on signals from the sensors 20 - 27 and she controls the electromagnetic valve 3 and PCV 10 , which then controls or regulates fuel injection and fuel pressure.

That is, the ECU 50 receives information regarding the degree of depression of the accelerator pedal ACCP, the coolant temperature THW, the fuel pressure PC, the fuel temperature THF, the intake pressure PM, and the vehicle speed SPD based on the signals from the accelerator pedal sensor 20 , the coolant temperature sensor 21 , the fuel pressure sensor 22 , the fuel temperature sensor 23 , the suction pressure sensor 24 and the vehicle speed sensor 27 , The ECU also calculates 50 the engine speed NE and the crankshaft angle CA based on the signals from the crankshaft sensor 25 and the cam sensor 26 ,

The ECU 50 controls fuel injection based on the values that drive the machine 1 play. More specifically, the ECU calculates 50 the basic injection amount QBASE based on the degree of depression of the accelerator pedal ACCP and based on the engine speed NE. The memory of the ECU 50 stores function data stored in 2 are shown. The function data defines the value of the basic injection amount QBASE based on the engine speed NE and the degree ACCP of depressing the accelerator pedal. The ECU 50 accesses the function data to calculate the basic injection quantity QBASE. As in 2 12, the value of the basic injection amount QBASE increases as the value of the amount ACCP in which the accelerator pedal is depressed increases, and in accordance with a value of the decrease in the engine speed NE.

The ECU 50 Also calculates the maximum injection amount QMAX based on the engine speed NE, the intake pressure PM, the coolant temperature THW, and the fuel temperature THF. The ECU 50 compares the maximum injection amount QMAX with the basic injection amount QBASE, and sets the lower value as the final injection amount QFIN.

If For example, the value of the engine speed NE is NE1 and the degree of ACCP depression of the accelerator pedal is ACCP1, the calculated basic injection amount QBASE is located at QBASE1. If the value of the calculated maximum injection amount QMAX is equal to QMAX1, the value QBASE1 is less than the value QMAX1. Therefore, it becomes the value QBASE1 of the basic injection amount QBASE as the final injection amount QFIN selected.

If the degree ACCP in which the accelerator pedal is depressed increases to the value ACCP2, with the engine speed NE at the value NE remains, the basic injection amount QBASE is QBASE2. In this case, the value of the maximum injection amount becomes QMAX equal to QMAX1. Since the value QMAX1 is smaller than the value QBASE2, is the maximum injection amount QMAX having the value QMAX1, as final Injection amount QFIN selected.

On this way will be the final one Injection amount QFIN always equal to or less than the maximum Fuel injection amount QMAX held. It is thus prevented that the Amount of fuel becomes excessively large, in relation to the amount of air entering the combustion chambers is initiated. This also limits the maximum value of the engine speed NE.

When the key switch 52 is in the ON position, the ECU is leading 50 various compensations for the final injection amount QFIN. The ECU 50 then controls the electromagnetic valve 3 based on the compensated final injection amount QFIN. As a result, the injector injects 2 an amount of fuel into the combustion chamber, which is represented by the compensated final injection amount QFIN. In this way, the amount of fuel injection is controlled so that it is for the running state of the machine 1 suitable is.

When the key switch 52 is moved to the OFF position, the ECU reduces 50 gradually the final injection amount QFIN and controls the fuel injection based on the reduced final injection amount QFIN. Therefore, when the key switch is turned off or turned off, the engine speed NE is gradually lowered, with lowering of the fuel injection amount, and the engine 1 is finally stopped. This process, in which the engine is stopped by gradually reducing the amount of fuel injection, is hereinafter referred to as "engine stop injection control". The engine stop injection control is performed to prevent the engine from vibrating when the engine is stopped. The engine stop injection control it also allows the crankshaft to rotate continuously for a predetermined period of time after the key switch 52 was turned off. Thus, the feed pump becomes 6 capable of discharging fuel.

The ECU also controls 50 the pressure in the common rail 4 , That is, the ECU 50 calculates a setpoint fuel pressure PTRG of the fuel pressure PC in the common rail 4 based on the basic fuel injection amount QBASE and the engine speed NE. The memory of the ECU 50 stores the function data that is in 3 are shown. The functional data of 3 define the value of the target fuel pressure PTRG based on the basic injection amount QBASE and the engine speed NE. The ECU 50 accesses the function data of 3 back to calculate the setpoint fuel pressure PTRG. As in 3 12, the value of the target fuel pressure PTRG increases as the value of the engine speed NE increases and as the value of the basic injection amount QBASE increases. This is because the fuel atomization must be promoted by increasing the fuel pressure PC in the common rail 4 when the on the machine 1 acting load is greater or when the engine speed NE is high.

The ECU 50 controls PCV 10 in such a way that the fuel pressure PC in the common rail 4 by the fuel pressure sensor 22 is detected, in accordance with the setpoint fuel pressure PTRG.

The relationship between the state of PCV 10 and the amount of fuel supplied by the feed pump 6 is discharged, is now with reference to a timing diagram of 4 described. 4 shows changes in the state of PCV 10 and the amount of fuel supplied by the feed pump 6 is discharged, in relation to the crankshaft angle CA. More specifically, the values (a), (c) and (e) represent different operating patterns of PCV 10 , the values (b), (d) and (f) represent fuel discharge patterns from the supply pump 6 corresponding to the PCV patterns (a) and (c) and (e), respectively, and the value (g) represents the raising of the piston in the feed pump 6 , In 4 are plotted on the horizontal axis, the changes in the crankshaft angle CA with time. The raising of the piston increases during a period between a time t2 and a time t6. This period corresponds to a discharge stroke of the feed pump 6 , The lifting of the piston is between the time 6 until that time 7 reduced. This period corresponds to the intake stroke of the pump 6 ,

During a period between a time t0 and a time t1, which are before the discharge stroke, PCV 10 opened, as illustrated in patterns (a), (c) and (e). Therefore, the pressure generating chamber of the feed pump 6 with the return line 11 over the return opening 6c connected and it does not become the fuel of the common rail 4 supplied from the pressure generating chamber.

At the time t1 becomes PCV 10 closed as shown in (a), (c) and (e). If PCV 10 is closed, the pressure generating chamber of the Rückführöff voltage 6c separated. Thus, fuel may be available for discharge in the pressure generating chamber in accordance with the raising of the piston.

At the time t2, the piston starts to pressurize the fuel in the pressure generating chamber, and the fuel in the pressure generating chamber begins to move to the common rail 4 over the discharge opening 6a and the feed tube 5 to move. After time t2, the amount of discharged fuel gradually increases as the increase of the piston increases.

If PCV 10 is opened in this state, the discharge of the fuel is stopped and the fuel in the pressure generating chamber becomes the fuel tank 8th over the return opening 6c and the return line 11 returned. The ECU 50 calculates the time to open PCV 10 for stopping the supply of the fuel to the common rail 4 based on the equation (1). The time to open PCV 10 is hereinafter referred to as "valve opening time TF". TF = TFBASE + K (PTRG - PC) (1)

In the equation (1), the value "K" is a coefficient of feedback control or gain. The value "K" is based on the position of the key switch 52 during a fuel pressure control routine, which will be described later.

The value "TFBASE" in the equation (1) is referred to as a reference value of a valve opening time TF. When the valve opening time TF coincides with the reference time TFBASE, the fuel pressure PC becomes in the common rail 4 held at the current pressure. The reference time TFBASE, which has been determined experimentally, is a function of the final injection amount QFIN and the fuel pressure PC. The memory of ECU 50 stores functional data defining the relationship between the reference time TFBASE and the final injection amount QFIN and the fuel pressure PC.

For example, the reference time TFBASE is set to a time t4 in the schedule of 4 set. When it is judged that the fuel pressure PC is less than the target fuel pressure PTRG (PTRG-PC> 0), the ECU delays 50 the valve opening time TF from the reference time TFBASE (time t4) to a time t5 (see (a) in FIG 4 ), which corresponds to a delayed crankshaft angle CA. This prolongs the period (from time t1-t5) during which PCV 10 closed is. As a result, the amount of fuel which is the common rail 4 is compared with a case where the valve opening time TF is the reference time TFBASE (see (b) in FIG 4 ). As a result, the fuel pressure PC is increased, and the difference between the fuel pressure PC and the target fuel pressure PTRG (PTRG-PC) is reduced.

When it is judged that the fuel pressure PC is greater than the target fuel pressure PTRG (PTRG-PC <0), the ECU stops 50 the valve opening time TF from the reference time FBASE (time t4) to a time t3 (see (e) in FIG 4 ), which corresponds to an advanced crankshaft angle CA. This shortens the period (from time t1 to time t3) during which PCV 10 closed is. It is therefore the amount of fuel, which is the common rail 4 is reduced, as compared with the case where the valve opening time TF is equal to the reference time TFBASE (see (e) in FIG 4 ). As a result, the fuel pressure PC is reduced, and the difference between the fuel pressure PC and the target fuel pressure PTRG (PTRG-PC) is reduced.

As from equation (1), the larger the Value of the difference between the fuel pressure PC and the setpoint pressure (PTRG-PC) is, the bigger the Value of the advance or delaying the valve opening time TF will. Thus, the fuel pressure PC converges to the target fuel pressure PTRG in a stable manner.

As described above, a predetermined amount of fuel becomes the common rail 4 during the pressure generation stroke (the period t2-t6) of the supply pump 6 fed. The pump 6 then moves to the intake stroke (period t6-t7). During the intake stroke, fuel is introduced into the fuel tank 8th into the pressure generating chamber via the suction opening 6b to prepare for the next discharge.

The fuel pressure control or fuel pressure control will now be described below. 5 FIG. 10 is a flowchart showing a routine for controlling the fuel pressure. FIG. The ECU 50 performs the routine in an interrupt manner at predetermined crankshaft angle increments.

When the routine is entered, the ECU assesses 50 whether a key switch flag XIG is on, which is at the step 100 he follows. The key switch flag XIG is used to indicate the position of the key switch 52 to judge. The key switch flag XIG is one when the key switch 52 is on the ON position, and is zero when the key switch 52 is in the OFF position. When the flag XIG is one, the ECU moves 50 to the step 106 and judges whether the engine speed NE is greater than zero, that is, the ECU 50 judges whether the feed pump 6 capable of supplying fuel to the common rail 4 supply.

If the determination at the step 106 Negative, that is, if the feed pump 6 is not in operation, the ECU moves 50 to the step 110 , If the determination at the step 106 positive, the ECU moves 50 on the other side to the step 107 , At the step 107 puts the ECU 50 the feedback coefficient K, which is used to calculate the valve opening time TF, to a predetermined value K1. The ECU 50 emotional. then to the step 108 , At the step 108 calculates the ECU 50 the target fuel pressure PTRG based on the current basic injection amount QBASE and the current engine speed NE.

If the determination at the step 100 is negative, that is, if the key switch 52 is in the OFF position, the ECU is moving 50 to the step 101 , At the step 101 assesses the ECU 50 whether a main relay flag XMR is one. The main relay flag XMR is always one when the key switch flag XIG is one. The flag XMR is changed from one to zero when writing malfunction diagnostic results and various processes to stop the machine 1 have been completed.

If the determination at the step 101 negative, that is, when the main relay flag XMR is zero, the ECU moves 50 to the step 110 , When the main relay flag XMR is set to zero, the winding becomes 51b de-energized and the switch 51a will be opened. As a result, the power becomes the ECU 50 completed.

If the determination at the step 101 positive, the ECU performs 50 the steps 102 - 105 out. The steps 102 - 105 are designed to fuel the PC in the common rail 4 on egg set the value for starting the machine 1 suitable is.

At the step 102 puts the ECU 50 a value NEOFF as the engine speed NE which is recorded when the switch 52 is moved from the ON position to the OFF position. Therefore, the engine speed NEOFF is the engine speed NE at a time when the key switch is turned off. Switching the key switch 52 is detected based on the fact that the key switch flag XIG which was one in the previous cycle of the routine is changed to zero in the current routine.

At the step 103 calculates the ECU 50 the requested pressure value PTRGSTA based on the coolant temperature THW. The requested fuel pressure PTRGSTA is a requested or desired value of the fuel pressure PC when the engine is restarted. The memory of the ECU 50 stores function data stored in 6 are shown. A solid line represents the relationship between the coolant temperature THW and the requested fuel pressure PTRGSTA. The ECU 50 uses this data to calculate the requested fuel pressure PTRGSTA. As in 6 is shown, the lower the coolant temperature THW is, the larger the value of the requested fuel pressure PTRGSTA becomes. A lower coolant temperature THW, which is a lower temperature of the machine 1 reflects, obstructs the atomization of the injected fuel. Therefore, the fuel pressure PC or the pressure of the injected fuel must be increased to promote the atomization of the injected fuel to start the engine 1 to simplify.

At the step 104 calculates the ECU 50 the feedback coefficient K based on the engine speed NEOFF when the switch 52 is moved to the OFF position. The memory of the ECU 50 stores the function data that is in 7 A solid line indicates the relationship between the feedback coefficient K and the engine speed NEOFF when the switch 52 is moved to the OFF position. The ECU 50 uses this data to calculate the feedback coefficient K. As in 7 is shown, the feedback coefficient K is always greater than the value K1, which in the step 107 is set when the key switch flag XIG is one. Also, the smaller the value of the engine speed NEOFF, the larger the value of the coefficient K becomes.

The feedback coefficient K is varied for the following reasons. When the key switch 52 is moved to the OFF position, the engine speed NE is lowered and the rotation of the crankshaft stops after a certain period. The feed pump 6 is capable of common rail oil 4 only to be supplied when the crankshaft is in rotation. Therefore, the fuel pressure PC must be increased to the target fuel pressure PTRG as early as possible by increasing the feedback gain or by adjusting the coefficient K accordingly.

Second, the lower the engine speed NEOFF, the shorter the period becomes, from the time the key switch is turned off 52 until the time when the crankshaft stops. Therefore, the feedback gain or coefficient K must be further increased when the engine speed NEOFF is relatively low.

In a subsequent step 105 substitutes the ECU 50 the requested fuel pressure PTRGSTA by the target fuel pressure PTRG.

After the execution of the step 105 or 108 or, if the determination at the step 101 or at the step 106 negative, the ECU moves 50 to the step 110 , At the step 110 calculates the ECU 50 the reference time TFBASE. The ECU 50 then moves to the step 112 and calculates the valve opening time TF based on the reference time TFBASE, further based on the feedback coefficient K, the target fuel pressure PTRG, and the fuel pressure PC. The ECU 50 Controls the time to close the PCV 10 based on the valve opening time TF in another control routine.

The control of the fuel pressure PC will now be described below. 8th FIG. 12 is a timing chart illustrating changes in the fuel pressure PC when the key switch. FIG 52 is turned off while the accelerator pedal 15 is not depressed at all and the engine speed NE gradually decreases.

The gas pedal 15 is released at a time t0. Thereafter, the target fuel pressure PTRG is lowered because the basic injection amount QBASE and the engine speed NE are lowered. As illustrated by a solid line, the fuel pressure PC is gradually lowered to a value PC1 lower than the requested fuel pressure PTRGSTA to the engine 1 to start.

The key switch 52 is turned off at a time t1 and the setpoint fuel pressure PTRG is replaced by the requested fuel pressure PTRGSTA, allowing for starting the engine 1 suitable is. The valve opening time TF is delayed when the fuel pressure PC is lower than the target fuel pressure PTRG (from the time t1 to the time t2). Therefore, the fuel pressure PC is increased to approach the target fuel pressure PTRG by increasing the fuel amount of the common rail 4 is supplied.

When the fuel pressure PC coincides with the target fuel pressure PTRG at the time t2, the valve opening time TF is changed to the reference valve opening time TFBASE. After time t2, the valve opening time TF is maintained at the reference valve opening time TFBASE. Thus, the fuel pressure PC is maintained at the target fuel pressure PTRG or at the requested fuel pressure PTRGSTA necessary for starting the engine 1 suitable is.

When the fuel injection and the fuel transfer are stopped at the same time when the key switch 52 is turned off, as is the case in the prior art, the fuel pressure PC is maintained at a value (PC1) indicated by a dashed line. The pressure PC1 is lower than the fuel pressure when the key switch 52 is turned off, that is, lower than the requested fuel pressure PTRGSTA, for starting the engine 1 suitable is. To restart the machine 1 For example, the fuel pressure PC must be increased to the requested fuel pressure PTRGSTA before fuel injection is started. This will increase the time it takes to start the machine 1 is required. In other cases, fuel that is not sufficiently atomized is injected into the combustion chambers. This causes the machine 1 can be started more difficult.

However, even if, in this embodiment, the fuel pressure PC is lower than the requested fuel pressure PRTGSTA when the key switch 52 is turned off, the pressure PC is increased to the requested fuel pressure PTRGSTA. Therefore, fuel is injected at a pressure necessary to start the engine 1 is suitable when the machine 1 is restarted. As a result, starting the engine is improved.

When the gas pedal 15 not completely depressed, that is, when the machine 1 When idling, the engine speed NE becomes low. A sudden increase in an external load on the machine 1 acts, in this state, the engine speed NE decreases. The decrease in engine speed NE can lead to stalling of the engine.

Therefore, in a typical diesel engine, the basic injection amount QBASE is then increased (for example, from the point A to the point B in FIG 2 ) when the engine speed NE drops while the engine is idling. Also, the target fuel pressure PTRG (for example, from the point A to the point B in FIG 3 ) increases as the basic injection amount QBASE increases. Increasing the basic injection amount QBASE and the target fuel pressure PTRG increases the engine speed NE, thereby causing the engine to spin 1 is prevented.

It does, however, in the diesel engine 1 Illustrated in this embodiment, the fuel injection amount is gradually reduced to prevent the engine from vibrating when the engine 1 is stopped. In this type of engine, the target fuel pressure PTRG may be set higher than the requested fuel pressure PTRGSTA when the engine speed NE is lowered.

For example, if the feedback control of the fuel pressure PC is simply continued after key switch 52 has been turned off, the fuel pressure PC of a two-point Strichlierungslinie in 8th consequences. That is, the fuel pressure PC is increased as the engine speed NE lowers, and is maintained at a value PC2 higher than the requested fuel pressure PTRGSTA. As a result, fuel is injected at a pressure higher than the requested fuel pressure PTRGSTA when the engine 1 is restarted. This leads to excessive atomization of the injected fuel, whereby the ignition pressure in the combustion chamber suddenly changes. The sudden change of the ignition pressure causes noise.

In the present embodiment, the target fuel pressure PTRG is not calculated based on the engine speed NE and the basic fuel injection amount QBASE after the key switch 52 has been turned off. Instead, the target fuel pressure PTRG is changed to the requested fuel pressure PTRGSTA, which is set based on the coolant temperature THW. Therefore, the fuel pressure PC does not exceed the requested fuel pressure PTRGSTA when the engine 1 is stopped. As a result, the machine arrives 1 not in a vibration state when stopped. Furthermore, noises of the machine 1 suppressed when the machine 1 is started.

Further, in the present embodiment, the lower the coolant temperature THW is, the higher the requested fuel pressure PTRGSTA becomes. Even if therefore the machine 1 is stopped before the machine 1 Warming up, starting the machine immediately afterwards does not prevent the atomization of the fuel. It thus improves the ignition of the machine. If on the other side the machine 1 is stopped, after it has been warmed up and then immediately started, the atomization of the fuel is optimally suppressed. This reduces the noise caused by starting the machine 1 caused.

After the key switch 52 has been turned off, the fuel pressure PC by the feed pump 6 elevated. Therefore, this embodiment does not require an extra pump for increasing the fuel pressure PC. This simplifies the construction of the fuel pressure control apparatus.

The feedback coefficient K (feedback gain) is increased after the key switch 52 has been turned off compared to a case where the switch 52 is in the ON position. This allows the fuel pressure PC to quickly reach the target fuel pressure PTRG. Thus, when the crankshaft is stopped, the fuel pressure PC is brought to the target fuel pressure PTRG before the feed pump 6 unable to increase the fuel pressure PC.

For example, if the key switch 52 is turned off, when the engine speed NE is low, the crankshaft is stopped in a relatively short period. However, the feedback coefficient K has a larger value for a lower engine speed NEOFF when the switch 52 is turned off. Therefore, even if the crankshaft is stopped in a short period after the key switch 52 has been turned off, the fuel pressure PC is positively increased, namely to the setpoint fuel pressure PTRG, before the feed pump 6 stops with their operation.

A second embodiment of the present invention will now be described. The differences between the embodiment according to the 1 - 8th are explained below and it is those components which are similar to or the same as the corresponding components of the embodiment according to the 1 - 8th provided with the same reference numerals.

In this embodiment, the control of the fuel pressure PC differs from that of the embodiment of FIGS 1 - 8th , In the embodiment according to the 1 - 8th the setpoint fuel pressure PTRG is changed to the requested or requested fuel pressure PTRGSTA after the key switch 52 was turned off. The valve opening time TF of PCV 10 is determined based on the difference (PTRG - PC) between the changed setpoint fuel pressure PTRG and the fuel pressure PC. In this embodiment, the feed pump 6 controlled so as to maximize their fuel discharge when the fuel pressure PC is lower than the target fuel pressure PTRG when the key switch 52 is turned off. When the fuel pressure PC is higher than the target fuel pressure PTRG, the supply pump becomes 6 controlled so as to stop the discharge of the fuel.

The control of the fuel pressure PC according to this embodiment will now be described below. 9 shows a flowchart with a routine for controlling the fuel pressure PC. This routine forms an interrupt by the ECU 50 is performed at predetermined Kurbelwellenwinkelinkrementen.

When the routine is entered, the ECU assesses 50 Whether a key switch flag XIG is at one, what at the step 200 he follows. If the determination is positive, the ECU moves 50 to the step 210 and judges whether the engine speed NE is greater than zero, that is, the ECU 50 judges whether the feed pump 6 capable of using common rail fuel 4 supply.

If the determination at the step 210 positive, the ECU is moving 50 to the step 212 , At the step 212 calculates the ECU 50 the valve opening time TF using the equation (1), and temporarily suspends the subsequent processing. The feedback coefficient K is a fixed value and is always equal to the value K1.

If the determination at the step 210 is negative, that is, when the crankshaft is not rotating and the feed pump 6 is not capable of discharging fuel, so the ECU continues 50 the subsequent processing temporarily off.

If the determination at the step 200 is negative, so moves the ECU 50 to the step 202 and judges whether the main relay flag XMR is one. If the determination is positive, the ECU moves 50 to the step 203 and judges whether the fuel pressure PC is lower than the requested fuel pressure PTRGSTA. As in the embodiment according to the 1 - 8th , the requested fuel pressure is PTRGSTA based determined on the coolant temperature THW.

If the determination at the step 203 That is, when the fuel pressure PC is equal to or higher than the requested fuel pressure PTRGSTA, the ECU moves 50 to the step 206 and temporarily stops controlling the PCV 10 , It will therefore be the PCV 10 kept open and communicates with the pressure generating chamber of the feed pump 6 with the return line or the return pipe 11 via the return opening 6c , Furthermore, the pump stops 6 temporarily the supply of fuel to the common rail 4 , In this case, if the fuel injection is continued after the key switch 52 was turned off, the fuel pressure PC suddenly drops. When the fuel injection is stopped, the fuel pressure PC is maintained at the current value.

If the determination at the step 203 positive, the ECU is moving 50 to the step 204 and changes the valve opening time TF to the largest delay time TFMAX. This maximizes the amount of fuel coming from the feed pump 6 is issued.

After the execution of the step 204 or 206 or, if the determination at the step 202 Negative, the ECU continues 50 the current routine temporarily off.

The embodiment according to 9 offers the following advantages.

When the fuel pressure PC is judged to be lower than the requested fuel pressure PTRGSTA after the key switch 52 turned off becomes PCV 10 controlled in such a way that the amount of fuel supplied by the feed pump 6 is spent, is maximized. This maximizes the speed with which the fuel pressure PC is brought to the requested fuel pressure PTRGSTA. Therefore, the fuel pressure PC is positively raised to the requested fuel pressure PTRGSTA after the crankshaft has stopped rotating and before the supply pump 6 unable to increase the fuel pressure PC.

When the fuel pressure PC is judged to be equal to or higher than the requested fuel pressure PTRGSTA after the key switch 52 was turned off, stops the feed pump 6 discharging or dispensing fuel. Therefore, the fuel pressure PC is positively lowered to the requested fuel pressure PTRGSTA after the engine 1 was stopped and before the fuel injection is stopped.

A third embodiment of the present invention will now be described. The differences from the embodiment according to the 1 - 8th are explained below substantially and those components which are similar to or the same as the corresponding components of the embodiment according to the 1 - 8th are provided with the same reference numerals.

As in the embodiment of the 1 - 8th the fuel pressure control routine of FIG 5 executed in this embodiment. Further, a fuel injection control is performed when the engine 1 is stopped.

The engine stop injection control does not start immediately after the key switch is turned off 52 executed. Instead, the normal fuel injection is continued based on the degree of depression of the accelerator pedal ACCP and based on the engine speed NE until a predetermined period of time has elapsed. That is, when the fuel pressure PC is higher than the requested fuel pressure PTRGSTA when the key switch 52 is turned off, the fuel pressure PC is lowered rapidly to the requested fuel pressure PTRGSTA. The time during which the normal fuel injection is continued is significantly short. In other words, the fuel pressure PC is lowered abge to the requested fuel pressure PRTGSTA within a very short time. Therefore, the continued normal fuel injection does not bother the driver who is using the key switch 52 turned off.

Now, the fuel injection will be described when the engine 1 is stopped. 11 FIG. 12 is a flowchart illustrating a fuel injection control routine when the engine is stopped. FIG. This routine forms an interrupt by the ECU 50 is executed at predetermined time intervals.

When the routine is entered, the ECU assesses 50 whether a key switch flag XIG is one, what at the step 300 he follows. If the determination is negative, the key switch is located 52 in the OFF position. The ECU 50 then moves to the step 302 and sets the engine speed NEOFF when the key switch 52 is turned off.

In a subsequent step 304 calculates the ECU 50 a fuel injection continuation time NECT based on the engine speed NEOFF when the key switch 52 is turned off. The continuation time NECT is a period calculated from the moment when the key switch 52 is turned off until because of the moment when the engine stop injection control is started. The memory of the ECU 50 stores the function data that is in 10 are shown. A solid line represents the relationship between the engine speed NEOFF and the fuel injection continuation time NECT. The ECU 50 uses this data to calculate the continuation time NECT.

As in 10 is shown, the larger the engine speed NEOFF, the longer the continuation time becomes NECT. This relationship between NEOFF and NECT will come out of the. following reason. The higher the engine speed NEOFF, the higher the fuel pressure PC, if the key switch 52 turned off or turned off. It therefore takes a long period of time to lower the fuel pressure PC to the requested fuel pressure PTRGSTA.

At the step 306 increments the ECU 50 a time period CIGOFF at a time equal to the length of the routine of 11 equivalent. The time period CIGOFF represents the time elapsed since the key switch 52 was turned off.

At the step 308 assesses the ECU 50 whether the time period CIGOFF has exceeded the continuation time NECT, that is, whether a predetermined time (namely NECT) has elapsed after the key switch 52 turned off or turned off. If the determination is negative, the ECU moves 50 to the step 310 , If the determination at the step 300 positive, the ECU is moving 50 to the step 320 and initializes the CIGOFF time period to zero. The ECU 50 then moves to the step 310 ,

At the step 310 sets the ECU 50 a flag XSTOP to zero. The flag XSTOP is used to judge whether the engine stop injection control has been started. The ECU 50 judges the state of the flag XSTOP in another injection control routine. If the flag XSTOP is zero, the ECU will execute 50 the normal fuel injection control. If the flag XSTOP is one, the ECU shifts 50 the normal fuel injection control to the engine stop injection control, which then the machine 1 is brought to a stop.

If the determination at the step 308 is positive, that is, when the predetermined time has elapsed since the key switch 52 has been turned off, the ECU is moving 50 to the step 312 and sets the flag XSTOP to one.

After performing the step 310 or 312 sets the ECU 50 the current routine temporarily off.

As described above, the engine stop injection control is started after the predetermined period has elapsed since the key switch 52 was turned off. In other words, the normal fuel control is performed for the predetermined period. The diesel engine 1 therefore continues to run normally for a predetermined time after the switch 52 has been turned off. Thereafter, the engine speed NE is gradually lowered until the engine 1 brought to a halt.

Changes in the engine speed NE and the fuel pressure PC are now made with reference to the timing plans of 12 and 13 described.

In 12 A solid line represents a case where the engine speed NEOFF is relatively low (NEOFF1), and a broken line represents a case where the engine speed NEOFF is relatively high (NEOFF2). In both cases, the key switch 52 switched off at a time t1.

In the case of the engine speed NEOFF1, the injection continuation time NECT consists of a period NECT1 lasting from time t1, at which time the key switch 52 is turned off or turned off until a time t2. During the period NECT1, the engine speed NE is maintained. At the time t2, the engine stop injection control is started, and the amount of injected fuel is gradually reduced. This gradually lowers the engine speed NE. At a time t3, the fuel injection is stopped, and consequently the combustion of the fuel is stopped. As a result, the engine speed NE drops off very quickly. The diesel engine 1 Stop running, at a time t4.

In the case of the engine speed NEOFF2, the injection continuation time NECT consists of a relatively long time period NECT2 (NECT2> NECT1). Therefore, the normal fuel injection is continued for a relatively long period of time (from the time t1 to a time t5). Thus, if NECT1 is used, then the total amount of fuel that is between the time the key switch is turned on 52 is turned off, and the time at which the diesel engine 1 is greater than the one injected during NECT1. In other words, the fuel pressure PC drops by a large amount.

The engine speed NEOFF is relatively high when the key switch 52 is turned off while the machine 1 is on the spin, that is, while the gas pedal 15 is pressed, wherein the selector lever is in a neutral position or a neutral range. Also immediately after the machine 3 has screwed through, performs a turning out of the key switch 52 before the engine speed NE lowers, to a relatively high engine speed NEOFF.

In this case, the target fuel pressure PTRG is set to a higher value based on the increased engine speed NE. Under these circumstances, the fuel pressure PC is higher than the requested fuel pressure PTRGSTA used to start the engine 1 suitable is. Therefore, the fuel pressure PC can not be lowered to the requested fuel pressure PTRGSTA by performing the engine stop injection control after the key switch 52 was turned off. As a result, fuel is injected at a pressure higher than the requested fuel pressure PTRGSTA when the engine 1 is restarted. This leads to a sudden change in the ignition pressure and causes noises.

However, in this embodiment, when the key switch 52 is rotated at the time t1, the target fuel pressure PTRG is changed to the requested fuel pressure PTRGSTA as in the first embodiment. This reduces the amount of fuel coming from the feed pump 6 discharged or delivered. Also, the normal injection is continued and the fuel pressure PC is suddenly lowered. At the time t2, the normal injection control is switched to the engine stop injection control. The amount of fuel injected is then gradually reduced. However, the fuel pressure PC is lowered continuously. At the time t3, the fuel pressure PC reaches the requested fuel pressure PTRGSTA. At the time t4 hears the diesel engine 1 with running on. From time t3 to time t4, the fuel pressure PC is maintained at the requested fuel pressure PTRGSTA. That is, the fuel pressure PC is reduced by the fuel injection. However, the feed pump sends 6 Fuel to the common rail 4 , which then causes the pressure in the common rail 4 is increased. As a result, a reduction of the fuel pressure PC is compensated.

The embodiment according to the 12 and 13 offers the following advantages.

Normal fuel injection continues after the key switch 52 was turned off. The fuel pressure PC therefore drops rapidly to the requested or requested fuel pressure PTRGSTA. Therefore, the injection pressure is not excessively high when the engine 1 is restarted. The sounds caused by starting the machine 1 caused are reduced accordingly.

It also applies, the higher the engine speed NEOFF is when the key switch 52 turned off, that is, the higher the fuel pressure PC is when the key switch 52 is turned off, the longer the normal injection control is continued. In other words, the injection continuation time NECT is prolonged. Therefore, even if the pressure PC deviates greatly from the requested or requested fuel pressure PTRGSTA, the fuel pressure PC is positively lowered to the requested fuel pressure PTRGSTA. If the fuel pressure PC deviates only slightly from the requested or requested fuel pressure PTRGSTA, the injection continuation time NECT is set short. It will therefore be the machine 1 immediately after the key switch 52 turned off, stopped.

Injectors 2 are used to reduce the fuel pressure PC after the key switch 52 was turned off. Therefore, this embodiment does not require an extra pressure controller, such as a pressure relief valve. This simplifies the construction of the fuel pressure control apparatus.

A fourth embodiment of the present invention will now be described. The differences from the embodiment according to the 10 - 13 are explained essentially below and those components which are similar to or the same as the corresponding components of the embodiment according to the 1 - 8th are provided with similar or identical reference numbers.

In the embodiment according to the 10 - 13 For example, the injection continuation time NECT is calculated based on the engine speed NEOFF when the key switch 52 is turned off. The normal fuel injection is continued until the time NECT has elapsed from the point when the key switch 52 turned off or turned off. In the fourth embodiment according to 14 However, the normal fuel injection continues until the fuel pressure PC has reached the requested fuel pressure PTRGSTA.

It will now be the fuel injection control when the engine 1 was stopped, pointing to 14 described. The underlying routine is an interrupt generated by the ECU 50 is executed at predetermined time intervals.

When the routine is entered, the ECU assesses 50 whether the key switch flag XIG is on, what at the step 400 he follows. If the determination is negative, the ECU assesses 50 that the key switch 52 is off and the program moves to the step 402 , At the step 402 reads the ECU 50 the instantaneous fuel pressure PC from the fuel pressure sensor 22 ,

In a subsequent step 408 assesses the ECU 50 whether the fuel pressure PC is lower than the requested fuel pressure PTRGSTA, in the routine of 5 is calculated. If the determination at the step 408 negative ver runs or if the determination at the step 400 is positive, the ECU is moving 50 to the step 410 , At the step 410 puts the ECU 50 the flag XSTOP to stop the machine 1 to zero.

If at the step 408 the determination is positive, that is, when the fuel pressure PC is lower than the requested fuel pressure PTRGSTA, the program of the ECU proceeds to the step 412 and this sets the flag XSTOP to one. After one of the steps 412 or 410 sets the ECU 50 the current routine is currently off.

Even if the key switch 52 is turned off, the engine stop injection control is not started until the fuel pressure PC is lower than the requested fuel pressure PTRGSTA. In other words, the normal injection control is continued. This embodiment thus has the same advantages as the embodiment according to FIGS 10 - 13 ,

According to the fourth embodiment 4 the fuel injection is not stopped until the fuel pressure PC has dropped below the requested fuel pressure PTRGSTA. Therefore, the fuel pressure PC is positively lowered to the requested fuel pressure PTRGSTA. When the fuel pressure PC is lower than the requested fuel pressure PTRGSTA when the key switch 52 is turned off, the engine stop injection control is started when the key switch 52 is turned off. The diesel engine 1 is therefore brought to a stop immediately.

A fifth embodiment of the present invention will now be described 15 described. The differences between the embodiment according to the 1 - 8th are explained below and those components that are similar to or the same as the corresponding components of the embodiment according to the 1 - 8th are provided with similar or identical reference numerals.

When in the embodiment of the 1 - 8th the key switch 52 is in the ON position and the engine speed NE is greater than zero (see step 108 in the routine of 5 ), the target fuel pressure PTRG is determined based on the basic injection amount QBASE and the engine speed NE. A value of the target fuel pressure PTRG corresponds to a value of the basic fuel injection amount QBASE and a value of the engine speed NE. According to the fifth embodiment 15 However, there is an upper limit of the target fuel pressure PTRG when the engine 1 is spinning. The target fuel pressure PTRG is controlled or regulated to remain below the upper limit.

The routine for calculating the target fuel pressure PTRG will now be referred to 15 described. This routine consists of an interrupt generated by the ECU 50 is executed at predetermined time intervals.

When the routine is entered, the ECU reads 50 the basic injection amount QBASE, the engine speed NE, the degree or the degree ACCP in which the accelerator pedal is depressed, and the vehicle speed SPD, which are at the step 500 he follows. At one step 502 calculates the ECU 50 the target fuel pressure PTRG based on the basic injection amount QBASE and the engine speed NE.

In a subsequent step 504 assesses the ECU 50 whether the vehicle speed SPD is zero. If the determination at the step 504 is positive, the ECU is moving 50 to the step 506 , At the step 506 assesses the ECU 50 whether the degree ACCP in which the accelerator pedal is depressed is greater than a predetermined value ACCP1. The value ACCP1 is used to judge whether there is a possibility that the target fuel pressure PTRG is set higher than the requested fuel pressure PTRGSTA. When the degree ACCP in which the accelerator pedal is depressed is larger than the predetermined value ACCP1, the ECU judges 50 in that the setpoint fuel pressure PTRG is set higher than the requested fuel pressure PTRGSTA due to an increased engine speed NE.

If the provisions in the steps 504 and 506 both are positive, the ECU assesses 50 that the machine 1 goes crazy and there is a movement to the step 508 ,

At the step 508 calculates the ECU 50 a maximum set point or target fuel pressure PTRGMAX based on the engine speed NE. The maximum target fuel pressure PTRGMAX forms an upper limit of the target fuel pressure PTRG. The memory of the ECU 50 stores function data stored in 16 are shown. A solid line represents the relationship between the maximum target fuel pressure PTRGMAX and the engine speed NE. The ECU 50 accesses the function data to calculate the maximum setpoint fuel pressure PTRGMAX. As in 16 is shown, the higher the engine speed NE, the larger the value of PTRGMAX becomes. The target fuel pressure PTRG is set to a larger value for a higher engine speed NE to assist the atomization of the fuel. Therefore, the value PTRGMAX must be determined accordingly.

At the step 510 assesses the ECU 50 whether the target fuel pressure PTRG is greater than the maximum target fuel pressure PTRGMAX. When the determination is positive, that is, when the target fuel pressure PTRG exceeds the maximum value PTRGMAX, the program of the ECU is executed 50 to the step 512 , At the step 512 substitutes the ECU 50 the maximum value PTRGMAX by the target fuel pressure PTRG.

After the execution of the step 512 or, if the determination in the steps 504 . 506 or 510 Negative, the ECU continues 50 the current routine is currently off.

The value of the target fuel pressure PTRG set in the current routine is in the memory of the ECU 50 temporarily stored. At the step 108 in the routine of 5 reads the ECU 50 the setpoint fuel pressure PTRG and performs the processes of the step 110 through and also the subsequent steps.

If, as described above, the machine 1 the setpoint fuel pressure PTRG is controlled to remain below the maximum setpoint fuel pressure PTRGMAX determined based on the engine speed NE.

17 Fig. 10 is a timing chart illustrating such a fuel pressure control. From a time t0 is the accelerator pedal 15 gradually depressed and the machine 1 starts to spin. Then, the fuel pressure PC starts to increase or increase as the target fuel pressure PTRG increases. If the increase in the target fuel pressure PTRG is not limited, the fuel pressure PC increases as indicated by a two-dot chain line when the degree ACCP in which the accelerator pedal is depressed increases. When the key switch 52 is turned off as the fuel pressure PC increases, the fuel pressure PC is lowered by the subsequent fuel injection (the engine stop injection control). However, if the fuel injection is stopped, the fuel pressure PC may become higher than the requested fuel pressure PTRGSTA, which is for starting the engine 1 suitable or cheap.

In this embodiment, however, the fuel pressure PC changes along the solid line of the graph of FIG 17 , In this graph, the degree ACCP in which the accelerator pedal is depressed is such that it exceeds the predetermined value ACCP1 at a time t1. Then, the target fuel pressure PTRG is controlled or regulated so as to remain below the maximum target fuel pressure PTRGMAX. In other words, the increase of the fuel pressure PC is suppressed after the time t1.

Even if therefore the machine 1 is stopped while spinning, or immediately after spinning, the fuel pressure PC is always lower than its maximum value PTRGMAX. Therefore, the injection pressure does not remain excessively high when the engine 1 is restarted. The sounds caused by starting the machine 1 caused are reduced accordingly.

The setpoint fuel pressure PTRG is not simply set to a lower value when the engine 1 but the maximum setpoint fuel pressure PTRGMAX is used. The setpoint fuel pressure PTRG is lowered to coincide with PTRGMAX only when PTRG exceeds the value PTRGMAX. In other words, the target fuel pressure PTRG is not controlled when it is below its maximum value PTRGMAX. It can therefore be a normal spin of the machine 1 as long as PTRG is lower than PTRGMAX.

A sixth embodiment of the present invention will now be described. The differences from the embodiment according to the 15 - 17 are described below and those components that are similar to or the same as the corresponding components of the embodiment according to the 1 - 8th , are provided with similar or identical reference numerals.

In the fifth embodiment according to the 15 - 17 the setpoint fuel pressure PTRG is limited when the engine 1 is spinning. However, in the sixth embodiment, the basic injection amount QBASE is lowered when the engine 1 is spinning. The target fuel pressure PTRG is calculated based on the reduced basic injection amount QBASE. In this way, the value of the setpoint fuel pressure PTRG is limited.

The routine for controlling the basic injection amount QBASE will now be referred to 18 described. This routine forms an interrupt by the ECU 50 is performed every predetermined period of time.

When the routine is entered, the ECU reads 50 the engine speed NE, the degree ACCP in which the accelerator pedal is depressed, and the vehicle speed SPD, which are at a step 600 he follows. At one step 602 calculates the ECU 50 the basic injection amount QBASE based on the values ACCP and NE.

In a subsequent step 604 assesses the ECU 50 whether the vehicle speed SPD is zero. If the determination is positive, the ECU moves 50 to the step 606 , At the step 606 assesses the ECU 50 whether the degree ACCP in which the accelerator pedal is depressed is greater than the reference value ACCP1, which is at the step 506 from 15 he follows.

If the provisions in the steps 604 . 606 are positive, the ECU assesses 50 that the machine 1 goes crazy and there is a movement to the step 608 ,

At the step 608 calculates the ECU 50 a maximum value QBASEMAX of the basic fuel injection amount QBASE based on the engine speed NE. The value QBASEMAX forms the upper limit of the basic fuel injection amount QBASE. The memory of the ECU 50 stores function data stored in 19 are shown. A solid line represents the relationship between the value QBASEMAX and the engine speed NE. The ECU 50 uses this data to calculate the value QBASEMAX. As in 19 is shown, the larger the engine speed NE, the larger the value QBASEMAX becomes. If the engine speed NE is relatively high, the fuel atomization must be increased. Therefore, the value QBASEMAX is increased to raise the target fuel pressure PTRG when the engine speed NE is high.

At the step 610 assesses the ECU 50 whether the basic injection value QBASE is greater than its maximum value QBASEMAX. If the determination is positive, the ECU moves 50 to the step 612 and substitutes the value of the maximum value QBASEMAX by the basic injection amount QBASE.

After the step 612 or, if the provisions in the step 604 . 606 or 610 Negative, the ECU moves 50 to the step 614 , At the step 614 compares the ECU 50 the basic injection amount QBASE having the maximum injection amount QMAX and substituting the smaller value by the final injection amount QFIN. The ECU 50 then temporarily expires the current routine.

The basic injection amount QBASE calculated in the current cycle of the routine is temporarily stored in the memory of the ECU 50 saved. The ECU 50 calculates the target fuel pressure PTRG based on the basic injection amount QBASE in the step 108 from 5 and then leads the step 110 out.

In this way, the maximum value QBASEMAX of the basic injection amount QBASE is calculated based on the engine speed NE. The basic injection amount QBASE is controlled to be smaller than the value QBASEMAX when the engine 1 is spinning.

20 FIG. 12 is a timing chart illustrating such a fuel injection control or injection control. FIG. From a time t0 on the accelerator pedal 15 gradually depressed and the machine 1 starts to spin. Then, the basic injection amount QBASE starts to increase as the degree ACCP increases, in which the accelerator pedal is depressed. If the increase in the basic injection amount QBASE is not limited, the value of QBASE continues to increase, as indicated by a two-dot chain line, as the degree ACCP in which the accelerator pedal is depressed increases. As the basic fuel injection amount QBASE increases, the target fuel pressure PTR increases. Thus, the fuel pressure PC increases significantly (refer to the two-dot chain line in FIG 17 ).

However, in this embodiment, when the degree ACCP in which the accelerator pedal is depressed exceeds the reference value ACCP1 at the time t1, the basic fuel injection amount QBASE increases along the solid line 20 to. That is, the basic fuel injection amount QBASE is controlled to be smaller than the maximum value QBASEMAX after time t1. As a result, the increase of the basic injection amount QBASE and the fuel pressure PC is suppressed (see the solid line in FIG 17 ).

The present invention embodiment therefore offers the same advantages as the embodiment according to FIGS 15 - 17 , More specifically, the basic fuel injection amount QBASE is controlled so as to be kept smaller than its maximum value QBASEMAX when the engine 1 is spinning. This prevents the engine speed NE from spinning excessively high.

Therefore, the amount of exhaust gas is reduced and the fuel economy is improved when the engine 1 is spinning.

The basic injection amount QBASE is not simply simply set to a lower value when the engine 1 is spinning. That is, the maximum basic fuel injection value QBASEMAX is used. The basic fuel injection amount QBASE is lowered so as to coincide with QBASEMAX only when QBASE exceeds the value QBASEMAX. In other words, the basic fuel injection amount QBASE is not controlled when it is below its maximum value QBASEMAX. It can therefore be a normal spin of the machine 1 as long as QBASE is lower than QBASEMAX.

A seventh embodiment of the present invention will now be described with reference to FIG 21 described. The differences from the embodiment according to the 18 - 20 are mainly explained and components which are similar to or the same as the corresponding components of the embodiment according to the 1 - 8th are provided with similar or identical reference numerals.

In the embodiment according to the 1 - 8th The basic injection amount QBASE is determined based on the degree ACCP in which the accelerator pedal is depressed. The target fuel pressure PTRG and the final injection amount QFIN are calculated based on the basic injection amount PTRG. Therefore, both the target fuel pressure PTRG and the final injection amount QFIN are functions of the degree ACCP in which the accelerator pedal is depressed as a parameter. In other words, the values PTRG and QFIN change in accordance with the value of ACCP.

However, in the seventh embodiment, the degree ACCP in which the accelerator pedal is depressed is set when the engine 1 is spinning. The basic injection amount QBASE is set based on the degree ACCP in which the accelerator pedal is depressed (hereinafter referred to as ACCPCON).

The routine for setting the degree ACCP in which the accelerator pedal is depressed will now be referred to 21 described. The routine forms an interrupt by the ECU 50 is executed at predetermined time intervals.

When the routine is entered, the ECU reads 50 the engine speed NE, the basic injection amount QBASE, the degree ACCP in which the accelerator pedal is depressed, and the vehicle speed SPD.

In a subsequent step 704 assesses the ECU 50 whether the vehicle speed SPD is zero. If the determination is positive, the ECU program will run 50 to the step 706 and it judges whether the degree ACCP in which the accelerator pedal is depressed is greater than the reference value ACCP1, as in the step 606 from 18 ,

If the provisions in the steps 704 . 706 both are positive, the ECU assesses 50 that the machine 1 goes crazy, and there is a movement to the step 708 , At the step 708 calculates the ECU 50 a maximum degree ACCPMAX in which the accelerator pedal is depressed based on the engine speed NE. The value ACCPMAX forms an upper limit of the degree ACCP in which the accelerator pedal is depressed. The memory of the ECU 50 stores function data stored in 20 are shown. A solid line represents the relationship between the value ACCPMAX and the engine speed NE. The ECU 50 uses this data to calculate the value ACCPMAX. The larger the engine speed NE, the larger the value ACCPMAX becomes. The fuel atomization must be increased when the engine speed NE is relatively high. Therefore, the target fuel pressure PTRG is thereby increased by increasing the value ACCPMAX.

At the step 710 assesses the ECU 50 whether the degree ACCP in which the accelerator pedal is depressed is greater than its maximum value ACCPMAX. If the determination is positive, that is, if ACCP is greater than ACCPMAX, the ECU moves 50 to the step 712 and substitutes the value of ACCPMAX by the value of ACCPCON used to set ACCP.

If in the steps 407 . 406 the determination is negative and also at the step 710 Negative, the ECU moves 50 to the step 714 , At the step 714 substitutes the ECU 50 the degree ACCP, in which the accelerator pedal is depressed, which also by the accelerator pedal sensor 20 is detected by the value ACCPCON.

After the step 712 or 714 sets the ECU 50 the running routine temporarily.

The ECU 50 calculates the basic injection amount QBASE based on the value ACCPCON. The ECU 50 then calculates the final injection amount QFIN based on the calculated basic injection amount QBASE, and calculates the target fuel pressure PTRG based on the basic fuel injection amount QBASE, which is the step 108 from 5 he follows.

Therefore, when the value ACCPCON is set to the maximum degree ACCPMAX in which the accelerator pedal is depressed, when the engine 1 the value of the basic injection amount QBASE is relatively small. Therefore, the values of the basic injection amount QBASE and the final injection amount QFIN calculated based on QBASE are relatively small. As a result, the present embodiment has the same advantages as the embodiment according to FIGS 18 - 20 ,

An eighth embodiment of the present invention will now be described with reference to FIGS 23 - 25 described. The differences from the embodiment according to the 1 - 8th are mainly explained and components that are similar to or the same as the components of the embodiment according to the 1 - 8th , are provided with similar or identical reference numerals.

23 shows a cross-sectional view illustrating a fuel pressure control device. The return opening 3a of each injector is with a fuel tank 8th via a return line 11 connected. The return line or the return pipe 11 is through an electromagnetic valve 12 regulated. The valve 12 includes a bobbin (not shown) and a pair of solenoids (not shown). The solenoids are located at the ends of the coil body (spool). The ECU 50 changes the position of the bobbin by energizing and de-energizing the solenoids, causing the return tube 11 opened and closed. When the control by the ECU 50 Once done, the valve remains 12 closed or opened until the next time the ECU 50 a signal to the valve 12 sends.

As described above, a portion of the fuel leaking to each injector leaks 2 is fed into the injector 2 when the injector 2 opens and closes. The leaked fuel becomes the fuel tank 8th from the return opening 3a via the return pipe 11 returned. When the injector 2 In general, fuel will not leak into the injector 2 , However, the injector owns 2 that the electromagnetic valve 3 contains a number of moving parts. Repeated sliding of the movable parts on guide parts creates a narrow space therebetween. Therefore, even if the injection device 2 is closed, a very small amount of fuel from the common rail 4 gradually into the injector 2 lick. The leaked fuel becomes the tank 8th via the return pipe 11 returned. This gradually reduces the fuel pressure PC, as in 25 is shown. According to 25 becomes the machine 1 stopped at a time t1 and the fuel pressure PC becomes equal to the requested fuel pressure PTRGSTA, that for starting the engine 1 is suitable or favorable at the time t1. However, the pressure PC is lowered according to the two-point dash line when fuel is injected into the injector 2 licks. When the machine 1 is restarted at a time t2, fuel is injected at a pressure PC lower than the requested or demanded fuel pressure PTRGSTA.

In this embodiment, the electromagnetic valve 12 controlled to avoid this disadvantage. 24 shows a flowchart of a routine for controlling the electromagnetic valve 12 , This routine forms an interrupt by the ECU 50 is executed at predetermined time intervals.

When this routine is entered, the ECU assesses 50 Whether the key switch flag XIG is one, which is at the step 800 he follows. If the determination is negative, that is, if the key switch 52 is in the OFF position, the program of the ECU is running 50 to the step 801 ,

At the step 801 calculates the ECU 50 the lowest reference value PCLOW and a highest reference value PCHI of the fuel pressure PC. The reference values PCHI and PCLOW are determined in relation to the requested or requested fuel pressure PTRGSTA. The highest reference value PCHI is set higher than the requested or requested pressure value PTRGSTA, and the lowest reference value PCLOW is set lower than the requested pressure value PTRGSTA.

In a subsequent step 802 assesses the ECU 50 whether the main relay flag XMR is one. If the determination is positive, the ECU moves 50 or their program for the step 804 ,

At the step 804 assesses the ECU 50 whether the fuel pressure PC is lower than the lowest reference value PCLOW. If the determination is negative lost, the ECU moves 50 to the step 808 , At the step 808 assesses the ECU 50 whether the fuel pressure PC is higher than the highest reference value PCHI.

If at the step 804 the determination is positive, that is, when the fuel pressure PC is lower than the lowest reference value PCLOW, the ECU moves 50 to the step 806 , At the step 806 controls the ECU 50 the valve 12 to the return pipe 11 close. This stops the flow of fuel from the injector 2 to the fuel tank 8th via the return pipe 11 ,

If at the step 808 the determination is positive, that is, when the fuel pressure PC is higher than the highest reference value PCHI, the ECU moves 50 to the step 812 , At the step 812 controls the ECU 50 the valve 12 to the return line or return pipe 11 to open. This allows a flow of fuel from the injector 2 to the fuel tank 8th via the return pipe 11 ,

If at the step 804 and 808 the determinations are negative, that is, when the fuel pressure PC is between the lowest reference value PCLOW and the highest reference value PCHI, the ECU controls 50 the valve 12 not and suspends the running routine temporarily.

In other words, the zone containing the requested fuel pressure PTRGSTA (PCLOW ≦ PC ≦ PCHI) is called a dead zone. The setting of a dead zone prevents the search in the electromagnetic valve 12 even if the fuel pressure PC fluctuates in the vicinity of the requested fuel pressure PTRGSTA.

If the determination at the step 800 is positive, the ECU is moving 50 on the other hand to the step 810 , At the step 810 assesses the ECU 50 Whether the engine speed NE is greater than the reference value NE1. The reference value NE1 is used to judge whether the machines 1 has entered the complete combustion state, or whether the engine speed NE has been sufficiently raised and the feed pump 6 enough fuel is discharged.

When the machine 1 for example, has not entered the complete combustion state after the key switch 52 has been switched on (NE ≤ NE1), the ECU controls 50 the valve 12 to the return pipe 11 to close, what at the step 806 he follows. It therefore becomes the fuel pressure PC which is at the requested fuel pressure PTRGSTA during non-operation of the engine 1 was held, not suddenly lowered when the key switch 52 is turned on. If on the other side the diesel engine 1 has entered the complete combustion state and the engine speed NE is relatively high (NE> NE1), the program of the ECU moves 50 to the step 812 , At the step 812 controls the ECU 50 the valve 12 to the pipe or pipe 11 to open. This creates the possibility of fuel entering the injector 2 licked into it, back to the fuel tank 8th flows, through the return line or the return pipe 11 , The leaked oil in the injector 2 therefore hinders the operation of the injector 2 Not.

If at the step 802 the determination is negative or even after the execution of the step 806 or 812 , sets the ECU 50 the running routine temporarily.

As described above, the electromagnetic valve becomes 12 closed when the fuel pressure PC is lower than the lowest reference value PCLOW after the key switch 52 was turned off. This prevents the fuel in the injector 2 to the fuel tank 8th via the return pipe 11 flows. Even if therefore fuel in the injector 2 licks while the machine 1 The fuel leak does not lower the fuel pressure PC. As by a solid line in 25 is shown, the fuel pressure PC is maintained substantially equal to the requested fuel pressure PTRGSTA, from the time t1 at which the engine 1 is stopped until the time t2 at which the machine 1 is restarted.

After the key switch 52 has been switched on, the return line 11 through the valve 12 be opened to prevent that from entering the injector 2 Oil leaked in the operation of the injector 2 with special needs. However, if the valve 12 is opened at the same time as the key switch 52 is turned on, is the feed pump 6 not capable of delivering enough fuel. This causes the fuel pressure PC held at the requested or requested fuel pressure PTRGSTA to drop abruptly.

Even if in this embodiment, the key switch 52 is screwed, the valve is 12 kept closed until the amount of fuel coming from the feed pump 6 is discharged, reaches a sufficient value. This prevents the fuel pressure PC from dropping abruptly when the engine 1 is started, causing the boot process of the machine 1 is promoted in a positive way.

A ninth embodiment of the present invention will now be described below Note on the 26 - 28 described. Components that are similar to or the same as corresponding components of the embodiment of FIG 1 - 8th are provided with the same reference numerals.

In the embodiment of the 1 - 8th the fuel pressure PC is in the common rail 4 held equal to the requested fuel pressure PTRGSTA, which is the optimum pressure value for starting the engine 1 is. However, if the electromagnetic valve 12 is used in the eighth embodiment, the fuel pressure PC may decrease as time passes. Further, when the electromagnetic valve 12 is used causes a long period of time between stopping the machine 1 and a subsequent starting operation of the machine, a reduction in the fuel pressure PC. If the machine is not put into operation for a long period of time, the machine will cool down. In such a case, it is difficult to sufficiently atomize the injected fuel when the engine 1 is started. Consequently, a satisfactory start of the machine 1 To ensure that it is preferable that the fuel pressure PC is increased, for a sufficient atomization of the injected fuel.

In this embodiment, the fuel pressure PC in the common rail 4 increased in a sudden manner. As in 28 is shown, then, when the starter 19 is pressed when the machine 1 is started, the ECU 50 setpoint fuel pressure PTRG to a relatively high value A1 and controls the PCV 10 in such a way that the fuel pressure PC in the common rail 4 is raised to the high setpoint A1. This increases the atomization of the injected fuel when the starter 19 is operated, in comparison with a case when the machine 1 normal operation begins. It will therefore be the machine 1 started in a satisfactory manner.

The ignition 19 will be unactivated when the machine 1 has started. In this condition, the fuel pressure PC need not be as high as when starting the engine 1 , Thus, when the starter signal STA changes to a state indicating OFF, the ECU stops 50 Setpoint fuel pressure PTRG to a value D1, which is lower than the value A1, and controls the PCV 10 in such a way that the fuel pressure PC in the common rail 4 becomes lower than the low target value D1.

However, it is difficult to immediately lower the fuel pressure PC from the high target value A1 to the low target value D1. Therefore, the fuel pressure PC actually decreases gradually, as indicated by a broken line in FIG 28 is displayed. The gradual decrease is by means of the check valve 7 causes (see 26 ), which in the supply line 5 between the feed pump 6 and the common rail 4 located to a reverse flow of fuel from the common rail 4 to the pump 6 to prevent. However, the check valve is 7 required for the fuel pressure PC in the common rail 4 at a desired value and thus can not be eliminated.

When the decrease of the fuel pressure PC gradually takes place, the atomization of the injected fuel becomes excessively high after the engine 1 was started. In this case, a sudden change in combustion pressure in the combustion chambers may generate noise.

Therefore, in this embodiment, the fuel pressure control apparatus includes a relief valve 17 in the common rail 4 , The ECU 50 opens the pressure relief valve 17 when certain conditions (which will be described later) are satisfied. If the pressure relief valve 17 opens, the fuel is in the common rail 4 via the return line or the return pipe 11 to the fuel tank 8th returned. This lowers the fuel pressure PC in the common rail 4 from.

27 FIG. 11 is a flow chart illustrating a routine for controlling the relief valve. FIG 17 reproduces. The ECU 50 performs the routine in an interrupt manner at predetermined time intervals.

If the ECU 50 enters the routine, the ECU leads 50 the step 901 to determine whether the starter signal STA, that of the starter switch 19 off, indicating an ON state or not. When the starter signal STA indicates an ON state, the starter becomes 19 actuated. In this case, the ECU is progressing 50 to the step 902 and sets the starter flag XSTA to one.

The ECU 50 then move to the step 903 and closes the pressure relief valve 17 , After that the ECU ends 50 temporarily the subsequent processing. According to 28 when the starter 19 is in an actuated state, the ECU provides 50 setpoint fuel pressure PTRG to a relatively high value A1 and controls the PCV 10 in such a way that the fuel pressure PC in the common rail 4 becomes equal to the higher setpoint A1. That is, the ECU 50 controls the PCV 10 to increase the amount of pressurized fuel supplied by the feed pump 6 is issued. If therefore the starter 19 is actuated, the pressure relief valve 17 closed. This immediately increases the fuel pressure PC in the common rail 4 , The setpoint A1 can be in line with the operating state of the machine 1 be set when the machine 1 starts.

If at the step 901 it is determined that the starter signal STA indicates an OFF state, the ECU determines 50 that the machine 1 has already been started and their program proceeds to the step 904 Ahead. At the step 904 determines the ECU 50 whether the starter flag XSTA is set to one. When it is determined that the starter flag XSTA is set to one, the ECU judges 50 in that the starter signal STA indicates an ON state before the present cycle of the routine is executed. In this case, the ECU is progressing 50 to the step 905 Ahead.

At the step 905 became the machine 1 started and the fuel pressure PC in the common rail 4 must therefore be lowered immediately. The ECU 50 therefore opens the pressure relief valve 17 , If the pressure relief valve 17 opens, fuel is in the common rail 4 via the return line 11 to the fuel tank 8th retumed. When the starter signal STA changes to an OFF state, the ECU stops 50 Setpoint fuel pressure PTRG to a low value D1 and controls the PCV 10 in such a way that the fuel pressure PC in the common rail 4 to the low setpoint D1 varies, as in 28 is shown. In other words, the ECU controls 50 the PCV 10 in such a way that the amount of pressurized fuel passing through the feed pump 6 is discharged, is reduced. Consequently, the pressure relief valve 17 immediately after the start signal STA indicates an OFF state, opened. This reduces the fuel pressure PC in the common rail 4 at a faster rate compared to the prior art. The target value D1 may be in accordance with the operating state of the engine 1 be changed.

At the step 906 determines the ECU 50 whether the fuel pressure PC, by the fuel pressure sensor 22 is detected, has been lowered to the low target value D1 or not. If the ECU 50 determines that the fuel pressure PC has not yet reached the target value D1, terminates the ECU 50 temporarily the subsequent processing and leads the step 901 . 904 . 905 . 906 repeatedly. As a result, the pressure relief valve remains 17 opened until the fuel pressure PC reaches the setpoint D1.

When it is determined that the fuel pressure PC has reached the target value D1, the ECU proceeds 50 to the step 907 and sets the starter flag XSTA to zero. After that the ECU ends 50 the subsequent processing.

By setting the starter flag XSTA to zero, the ECU advances 50 to the step 903 from the step 904 off when the next cycle of this routine is executed. In this case, the ECU closes 50 the pressure relief valve 17 at the step 903 and prevents fuel in the common rail 4 via the return line 11 to the fuel tank 8th can return.

As described above, in this embodiment, the relief valve becomes 17 opened immediately after the starter signal STA has changed from the ON state to an OFF state. This immediately reduces the fuel pressure PC in the common rail 4 to a value that optimally reflects the normal operating condition of the machine 1 equivalent. As a result, the injected fuel is atomized appropriately and noise is not generated immediately after the engine is started 1 ,

In this embodiment, the pressure relief valve 17 in the common rail 4 arranged. The pressure relief valve 17 However, it can also be arranged at other positions as long as the valve 17 downstream of the check valve 7 is located. Furthermore, the pressure relief valve 17 can also be replaced by any type of device that can lower the fuel pressure PC. For example, an apparatus that performs invalid injection control, such as that described in Japanese Unexamined Patent Publication No. 2-191865, may be used instead of the relief valve 17 be used.

It is now referring to the 29 - 31 A tenth embodiment of the present invention is described. The tenth embodiment constitutes a modification of the embodiment shown in FIGS 26 - 28 is illustrated. Components that are similar to or the same as the corresponding components of the embodiment according to the 26 - 28 are provided with the same reference numerals.

In the embodiment of the 26 - 28 becomes the pressure relief valve 17 opened immediately when the starter signal STA changes from a state indicating ON to a state indicating OFF, to the pressure in the common rail 4 lower. In this embodiment, however, the pressure relief valve 17 omitted. Instead of the pressure relief valve 17 becomes PCV 10 controlled in such a manner that the fuel pressure PC decreases by a certain value, during the period of time, starting from the moment when the starter signal STA changes from the ON state, and ending in the moment when the starter signal STA changes to an OFF state.

29 shows a flowchart illustrating a routine for controlling the PCV 10 shows. The ECU 50 performs the routine in an interrupt fashion for each predetermined time interval.

When the routine is entered, the ECU performs 50 first the step 121 and determines whether the starter signal STA, that of the starter switch 19 is emitted, indicating an ON state. When the starter signal STA indicates an ON state, the starter becomes 19 actuated. In this case, the ECU is progressing 50 to the step 122 and adds one in an incremental manner to the previous count SCTAON indicating the elapsed time from the moment the starter is started 19 is pressed, in the previous cycle, and which renews the count SCTAON with the obtained sum. The count SCTAON indicates the elapsed time from the moment the starter is started 19 was pressed.

At the step 123 determines the ECU 50 whether the starter flag XSTA is set to zero or not. When the starter flag XSTA is set to zero, the starter signal STA has indicated an OFF state before entering the current cycle of this routine. In this case, the ECU is progressing 50 to the step 124 and sets the starter flag XSTA to one.

At the step 125 puts the ECU 50 setpoint fuel pressure PTRG to a relatively high value A1 (see 31 ). At the step 126 calculates the ECU 50 a holding time TPT based on the coolant temperature THW. Dwell time TPT refers to the time period during which the target fuel pressure PTRG must be maintained at the high target value A1. The fuel pressure PC in the common rail 14 , for a satisfactory start of the machine 1 is required is guaranteed when the setpoint fuel pressure PTRG is maintained at the high setpoint value A1 over the hold time TPT.

The ECU 50 includes a memory storing function data for defining the relationship between the coolant temperature THW and the withstand time TPT, as shown in FIG 30 is shown. The ECU 50 accesses the function data to calculate the hold time TPT. As in the graph of 90 is shown, the withstand time TPT is set in such a manner that it becomes longer as the coolant temperature THW becomes lower. When the coolant temperature THW is low, the engine temperature is also low. In this case, it is difficult to atomize the injected fuel in a proper manner. It is therefore necessary to extend the hold-up time TPT in order to atomize the injected fuel for a satisfactory starting of the engine 1 to promote or increase.

At the step 127 determines the ECU 50 whether or not the count value SCTAON has reached a value which corresponds to the withstand time TPT or not, which at the step 126 was obtained. When it is determined that the count value SCTAON has not yet reached the withhold time TPT, the ECU ends 50 temporarily the subsequent processing.

Although in the flow chart of 29 not shown, steps similar to those of step 110 and 112 shown in the flow chart of the first embodiment ( 5 ) after determining the target fuel pressure PTRG to calculate the valve opening time TF. As a result, the ECU controls 50 the PCV 10 in accordance with the valve opening time TF in such a manner that the fuel pressure PC in the common rail 4 becomes equal to the setpoint fuel pressure PTRG.

If at the step 123 it is determined that the starter flag XSTA is set to one, the ECU proceeds 50 to the step 131 Ahead. As described above, the starter flag XSTA is set to zero immediately after the starter signal STA changes from a state indicating OFF to a state indicating ON. In such a state, the starter flag XSTA becomes one at the subsequent step 124 set. As a result, the ECU proceeds 50 when the processing of the step 124 - 126 has been executed, from the step 123 to the step 131 until the starter signal STA indicates an OFF state.

At the step 131 determines the ECU 50 Whether the current target fuel pressure PTRG is set to the value C1 or not. The target fuel pressure PTRG is replaced by the value C1 after the sustain time TPT has elapsed and before the starter signal STA changes to an OFF state. Further, the value C1 is lower than the value A1 and higher than the value D1 set as the target fuel pressure PTRG when the starter signal STA changes to an OFF state (see FIG 31 ). If the current target fuel pressure PTRG has not yet reached C1, the ECU proceeds 50 to the step 127 Ahead.

When it is determined that the count value SCTAON has reached a value which is the withhold time TPT at the step 127 corresponds, the ECU moves forward 50 to the step 128 Ahead. At the step 128 puts the ECU 50 Setpoint fuel pressure PTRG to a value B1. The value B1 is variable and varies with the values A1 and C1. In addition, the value B1 is increased by a predetermined amount α is reduced every time the ECU 50 the step 128 performs.

The ECU 50 then move to the step 129 and determines whether the current setpoint fuel pressure PTRG has reached the minimum B1 or value B1LG or the value C1. When it is determined that the target fuel pressure PTRG has not yet reached the value B1LG, the ECU ends 50 temporarily the subsequent processing. Thus, after the count value SCTAON has reached a value corresponding to the hold-out time TPT, the target fuel pressure PTRG gradually decreases until the value B1LG is reached (see FIG 31 ).

When it is determined that the current target fuel pressure PTRG is the value B1LG at the step 129 has reached, the ECU is progressing 50 to the step 130 and set the target fuel pressure PTRG to the value C1, which corresponds to the value D1LG. The ECU 50 subsequently terminates the subsequent processing temporarily.

Accordingly, after the target fuel pressure PTRG has been set to the value C1, the ECU proceeds 50 not from the step 131 to the step 127 if the starter signal STA does not change to an OFF state. In other words, when the target fuel pressure PTRG once to the value C1 in the step 130 has been set, the target fuel pressure PTRG is maintained at C1 until the starter signal STA changes to an OFF state (see FIG 31 ).

When it is determined that the starter signal STA at the step 121 indicates an OFF state, the ECU proceeds 50 to the step 132 Ahead. At the step 132 determines the ECU 50 in that starting the machine 1 has been completed and sets the target fuel pressure PTRG to the low value D1 (see 31 ).

The ECU 50 then move to the step 133 and sets the starter flag XSTA to zero. At the step 134 clears the ECU 50 the count SCTAON and returns this to zero. The ECU 50 then temporarily stops the subsequent processing. In other words, the ECU controls 50 after the machine 1 started and starts with its normal operation, the PCV 10 in accordance with the target value D1, which is lower than the target value A1, which is used when the engine 1 is started.

As in 31 is shown represents the ECU 50 the setpoint fuel pressure PTRG to the high value A1 when the starter 19 is pressed. After maintaining or maintaining the setpoint fuel pressure PTRG at the high value A1 over a period corresponding to the hold time TPT, which is the minimum time necessary for a satisfactory engine start 1 is required, the target fuel pressure PTRG is gradually lowered until it reaches the value C1. If therefore the starter 19 is deactivated or is no longer actuated, the fuel pressure PC in the common rail 4 lowered to the value C1, which is lower than the high setpoint A1. The time required for lowering the fuel pressure PC from the value C1 to the value D1 is shorter than the time required for lowering the fuel pressure PC from the value A1 to the value D1. Therefore, if the starter 19 is deactivated, the fuel pressure PC is reduced immediately to the value D1, which is the optimum value for the normal operation of the machine 1 is. Consequently, the advantages of the embodiment incorporated in the 26 - 28 are also achieved in this embodiment.

When the fuel pressure PC is excessively lowered while the starter 19 is in an actuated state, the starting of the machine runs 1 in an unsatisfactory way. In this embodiment, however, the fuel pressure does not become lower than the value C1 when the starter 19 is pressed. It is therefore prevented that the fuel pressure PC becomes too low when the engine 1 is started. As a result, the machine starts satisfactorily 1 ensured.

In contrast to the embodiment according to the 26 - 28 is the pressure relief valve 17 not provided. This simplifies the design of the fuel control device and also reduces costs.

In this embodiment, the withstand time TPT of the target value A1 is based on the coolant temperature THW. However, the withstand time TPT may also be based on other parameters, which are the temperature of the machine 1 Show. As another option, the hold time TPT may be a fixed or fixed value.

Of the Setpoint fuel pressure PTRG can be at the high value A1 as long are held until the engine speed NE is a predetermined value has reached. When the engine speed NE is a predetermined one Value has been achieved, a satisfactory start-up is guaranteed, regardless of the fuel pressure PC, which is low.

In this embodiment, the target fuel pressure PTRG is lowered in a linear manner as shown by a graph as in FIG 31 is illustrated. However, the setpoint fuel pressure PTRG may also be in one Curve type can be reduced if this is represented by a graph.

For professionals it is obvious that the present Invention can be implemented in many other specific forms can, without, however, the scope of the present invention, such he in the claims is described, leave. Specifically, it should be noted that the Invention in the following embodiments accomplished can be.

In the embodiments according to the 1 - 20 The requested fuel pressure PTRGSTA is calculated based on the coolant temperature THW. However, as indicated by the two-dot line in 6 12, the value of PTRGSTA may be constant at any given coolant temperature THW. Further, PTRGSTA may also increase with the increase of the fuel temperature THF. This then makes the fuel pressure PC more appropriate to the engine 1 to start.

In the embodiments according to the 1 - 20 the feedback coefficient K is changed when the key switch 52 turned off or turned off. However, the value of the feedback coefficient K may be kept constant regardless of the turn-off of the switch 52 , Alternatively, as in 7 is shown, the feedback coefficient K consist of a value K1 before the key switch 52 is turned off, and can be switched to a value K2 which is greater than the value K1, after the key switch 52 was turned off.

In the embodiment according to the 10 - 13 For example, the normal injection control is continued until the injection continuation time NECT calculated based on the engine speed NEOFF has elapsed since the key switch 52 was turned off. However, the engine stop injection control may be started when the key switch 52 is turned off. Further, the ratio of the decrease of the fuel injection amount for a higher value of the engine speed NEOFF may be controlled to be smaller. This construction positively reduces the fuel pressure PC to the requested or requested fuel pressure PTRGSTA when the fuel pressure PC is relatively high when the key switch 52 is turned off.

In the embodiment according to the 10 - 13 For example, the injection continuation time NECT is set longer for a higher value of the engine speed NEOFF. However, the injection continuation time NECT may consist of a constant value NECT3 as indicated by a two-dot line in FIG 10 is displayed. The time NECT3 is preferably set to a value which lowers the fuel pressure PC to the requested fuel pressure PTRGSTA at any engine speed NEOFF, that is, any value of the fuel pressure PC at the time of turning out the key switch 52 ,

In the embodiment according to the 10 - 13 the injection continuation time NECT is calculated based on the engine speed NEOFF. However, the value of the injection continuation time NECT may be changed to a value QCT by making part of the routine of FIG 11 will be changed.

At the step 302 in the routine of 11 becomes the basic injection amount QBASE when the key switch 52 is turned off, as a value denotes QBASEOFF. After that, at the step 304 , calculates the ECU 50 the injection continuation time QCT based on the value QBASEOFF. A higher value of QBASEOFF results in a higher fuel pressure PC when the key switch 52 is turned off. It therefore takes a longer time to lower the fuel pressure PC to the requested or requested fuel pressure PTRGSTA. Therefore, similar to the relationship between the engine speed NEOFF and the injection continuation time NECT in FIG 10 extends the injection continuation time QCT for a larger value of QBASEOFF. This construction has the same advantages as those of the embodiment according to FIGS 10 - 13 ,

In the embodiment according to 14 the flag XSTOP will stop the machine 1 is set to one when the fuel pressure PC is lower than the requested fuel pressure PTRGSTA, that is, when the determination in the step 408 in 14 is positive. This then stops the normal injection control. In other words, the requested fuel pressure PTRGSTA is used as a criterion for determining whether the normal injection control should be stopped. The engine stop injection control is executed immediately after the normal injection control. Thus, the fuel pressure PC can either be increased or reduced during engine stop injection control. Therefore, the values other than PTRGSTA can be used as a criterion.

In the embodiments according to the 15 - 22 will be the maximum setpoint fuel pressure PTRGMAX, the maximum Basic injection amount QBASEMAX and the maximum degree ACCPMAX in which the accelerator pedal is depressed is used, and the target fuel pressure PTRG, the basic injection amount QBASE and the degree ACCP in which the accelerator pedal is depressed are controlled to be lower remain as the value PTRGMAX, QBASEMAX and ACCPMAX. However, the values PTRG, QBASE, and ACCP may be multiplied by a compensation coefficient that is less than one, for example, when the machine 1 is spinning. This also limits the values PTRG, QBASE and ACCP.

In the embodiments according to the 15 - 22 For example, the maximum values PTRGMAX, QBASEMAX and ACCPMAX of the target fuel pressure PTRG, the basic injection amount QBASE and the degree ACCP in which the accelerator pedal is depressed are increased for a higher engine speed NE. However, the values PTRGMAX, QBASEMAX and ACCPMAX may also be kept constant as indicated by the two-dot chain lines in the 16 . 19 and 22 is shown, at any engine speed NE.

In the embodiment according to the 15 - 22 becomes the machine 1 judged as spinning when the vehicle speed SPD is zero, and the degree ACCP in which the accelerator pedal is depressed is equal to or greater than ACCP1. However, the machine can 1 also be judged as spinning when the gear selector lever is in the neutral position or in the parking position and when the degree ACCP in which the accelerator pedal is depressed or the engine speed NE is equal to or greater than a reference value. Alternatively, the values PTRG, QBASE and ACCP can be easily limited when the transmission selector lever is in the neutral position or also in the park position, that is when the engine is running 1 is spinning.

In the embodiments according to the 10 - 14 the fuel pressure PC is in the common rail 4 lowered to the requested fuel pressure PTRGSTA by injectors 2 be caused to inject fuel. Alternatively, a pressure relief valve, as in the embodiment according to the 26 - 28 is illustrated in the common rail 4 be provided. In this case, the ECU controls 50 the pressure relief valve to lower the fuel pressure PC.

In the embodiments according to the 1 - 10 . 15 - 17 and 23 - 25 Normal fuel injection continues until a predetermined period of time since the key switch was turned off 52 has passed. However, the fuel injection may be stopped at the same time as the key switch 52 is turned off. In this case, the crankshaft turns off and stops the feed pump 6 active until the crankshaft has come to a complete stop. During this time is the feed pump 6 capable of carrying fuel.

The present invention can be practiced with a direct injection gasoline engine in which the injectors inject fuel directly into the combustion chambers. A direct injection gasoline engine includes a transfer tube in which fuel under high pressure is stored. The transfer tube corresponds to the common rail 4 at the diesel engine 1 ,

at the illustrated embodiments is pressurized fuel in a common rail or injected in an accumulator from the injectors. However, the device can according to the present invention also in a machine for use arrive where a fluid, such as machine oil, from a pump is sent to an accumulator, and the pressure of the fluid in the accumulator is used to fuel injectors to inject.

It Therefore, the present examples and embodiments are merely as illustrative and not in a limiting sense, and the present invention is obviously not in any detail limited, which are presented here, but may be in the context and in equivalence to the attached claims be modified.

Claims (22)

Device for controlling the fuel pressure in a machine, which device comprises: - an accumulator ( 4 ) for storing high pressure fuel supplied by a pump ( 6 ) is delivered; An injection device ( 2 ) for injecting the in the accumulator ( 4 ) stored fuel in a combustion chamber of the machine; and - an adjustment device ( 50 . 10 ) for adjusting the pressure of the fuel in the accumulator ( 4 ) according to the running state of the machine, - the device being characterized in that the adjusting device ( 50 . 10 ) the fuel pressure in the accumulator ( 4 ) is adjusted to approach a predetermined desired value suitable for subsequent starting of the engine, within a perio de, from the initialization of an operation to stop the machine until the time when the machine is completely stopped. Device according to claim 1, characterized in that the adjusting device ( 50 . 10 ) calculates the desired value based on the temperature of the engine when the engine stop operation is initialized. Device according to claim 2, characterized in that that, ever higher the Machine temperature is, the lower the calculated desired value is. Device according to one of claims 1 to 3, characterized in that during normal machine operation the fuel pressure in the accumulator ( 4 ) based at least on the engine speed. Device according to one of claims 1 to 4 , characterized in that the adjusting device ( 50 . 10 ) regulates the amount of fuel supplied to the accumulator ( 4 ) from the pump ( 6 ) is supplied to the fuel pressure in the accumulator ( 4 ). Device according to Claim 5, characterized in that, when the machine stopping operation is initialized, the adjusting device ( 50 . 10 ) maximizes the amount of fuel coming from the pump ( 6 ) is supplied when the fuel pressure in the accumulator ( 4 ) is lower than the desired value, and the adjustment device ( 50 . 10 ) the pump ( 6 ) continues to supply fuel when the fuel pressure in the accumulator ( 4 ) is equal to or greater than the desired value. Device according to one of claims 1 to 6, characterized in that the adjusting device ( 50 . 10 ) the injection device ( 2 ) to continue the fuel injection to increase the fuel pressure in the accumulator ( 4 ) to the desired value until a predetermined time period has elapsed from the point when the engine stop operation is initialized. Apparatus according to claim 7, characterized in that the adjusting device ( 50 . 10 ) the length of the predetermined period in accordance with the fuel pressure in the accumulator ( 4 ) is determined when the machine stop operation is initialized. Apparatus according to claim 8, characterized in that the higher the fuel pressure in the accumulator ( 4 ), the longer the predetermined period. Apparatus according to claim 8 or 9, characterized in that the adjusting device ( 50 . 10 ) detects the engine speed which determines the fuel pressure in the accumulator ( 4 ). Device according to one of claims 1 to 6, characterized in that the adjusting device ( 50 . 10 ) the injection device ( 2 ) causes the fuel injection to continue until the fuel pressure in the accumulator ( 4 ) has dropped to the desired value from the time when the machine stop operation is initialized. Device according to Claim 1, characterized in that, when the machine is spinning, the adjusting device ( 50 . 10 ) the fuel pressure in the accumulator ( 4 ) limited. Apparatus according to claim 12, characterized in that the adjusting device ( 50 . 10 ) a setpoint of the fuel in the accumulator ( 4 ) is calculated based on at least the engine speed and at which the adjustment device ( 50 . 10 ) limits the setpoint when the machine is spinning. Apparatus according to claim 13, characterized in that the adjusting device ( 50 . 10 ) limits the setpoint such that the setpoint does not exceed an upper limit that is determined or predetermined in accordance with the engine speed. Apparatus according to claim 12, characterized by a computer for calculating the amount of fuel passing through the injector (10). 2 ), based on at least the engine speed, wherein the adjustment device (10) 50 . 10 ) limits the calculated injection quantity when the engine is spinning. Apparatus according to claim 15, characterized in that the adjusting device ( 50 . 10 ) limits the calculated injection amount such that the calculated injection amount does not exceed an upper limit value determined in accordance with the engine speed or determined in advance. Device according to claim 1, characterized by: - a prevention device ( 7 ) to prevent the fuel from flowing back to the pump ( 6 ) from the accumulator ( 4 ) to flow out; A determination device ( 50 ) to determine whether the running state of the engine has changed from a first state to a second state, the first state requiring that the fuel pressure in the accumulator ( 4 ) quite high and wherein the second state is a fuel pressure in the accumulator ( 4 ), which is low compared to the first state, and wherein the adjustment device ( 50 . 10 ), regulates the amount of fuel supplied to the accumulator ( 4 ) from the pump ( 6 ) is supplied to the fuel pressure in the accumulator ( 4 ) to the required value; and - a release device ( 17 ) for releasing the fuel downstream of the prevention device ( 7 ) is present to directly monitor the fuel pressure in the accumulator ( 4 ) when the running state of the engine changes from the first state to the second state. Apparatus according to claim 17, characterized in that the release device consists of a release valve ( 17 ) to recover fuel from the accumulator ( 4 ). Device according to claim 1, characterized by: - a prevention device ( 7 ) to prevent fuel from the accumulator ( 4 ) back to the pump ( 6 ) to flow; and a determination device ( 50 ) to determine whether the running state of the engine has changed from a first state to a second state, the first state requiring that the fuel pressure in the accumulator ( 4 ) has a relatively high value, the second state requires that the fuel pressure in the accumulator ( 4 ) has a relatively low pressure, wherein the adjustment device ( 50 . 10 ) regulates the amount of fuel supplied by the pump ( 6 ) to the accumulator ( 4 ) is transferred to the fuel pressure in the accumulator ( 4 ) to the required value, and wherein the adjusting device ( 50 . 10 ) the fuel pressure in the accumulator ( 4 ) decreases from the high value to an intermediate value that is between the high value and the low value before the running state of the engine changes from the first state to the second state. Device according to Claim 19, characterized in that, when the running state of the machine reaches the first state, the adjusting device ( 50 . 10 ) the fuel pressure in the accumulator ( 4 ) gradually decreases to the intermediate value, after maintaining the fuel pressure in the accumulator ( 4 ) at the high value for a certain period of time. Device according to claim 20, characterized in that that, ever the lower the temperature of the machine, the longer the certain time period is. Device according to one of Claims 17 to 21, characterized in that the determining device ( 50 ) determines that the running state of the machine is in the first state when a starter ( 19 ) works to boost the machine and in which the determining device ( 50 ) determines that the running state of the engine is in the second state when the starter ( 19 ) is stopped.