JP2867005B2 - Fuel injection device for internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel injection device for an internal combustion engine having a fuel injection pump and a fuel injection nozzle for injecting fuel into the internal combustion engine.

[0002]

2. Description of the Related Art Conventionally, in a fuel injection device for an internal combustion engine provided with a fuel injection pump and a fuel injection nozzle, various methods have been employed in order to match the fuel injection amount and the fuel injection timing from the fuel injection nozzle to the target values. Is performed.

For example, in an electronically controlled diesel engine, the fuel in a high-pressure chamber is pumped to a fuel injection nozzle and injected into each cylinder of the engine by a lift of a plunger in a fuel injection pump. Then, the spill ring, the spill valve, and the like provided in the fuel injection pump are driven and controlled by the actuator such that the fuel injection amount at that time becomes the target injection amount determined according to the operation state of the engine. By this control, the high-pressure chamber of the plunger is opened to the fuel chamber, and a part of the fuel in the high-pressure chamber overflows (spills) to the fuel chamber. Thus, the end of the pressure feeding of the fuel from the fuel injection pump to the fuel injection nozzle, that is, the end timing (fuel injection amount) of the fuel injection from the fuel injection nozzle to each cylinder is controlled. Alternatively, a timer device provided in the fuel injection pump is drive-controlled so that the fuel injection timing becomes a target injection timing determined according to the operation state of the engine. By this control, the reciprocating timing of the plunger is adjusted, and the timing of fuel pumping from the fuel injection pump to the fuel injection nozzle, that is, the fuel injection start timing (fuel injection timing) at the fuel injection nozzle is retarded or advanced. Controlled to the side.

[0004] However, even in the electronically controlled diesel engine as described above, the fuel system from the fuel injection pump to the fuel injection nozzle has a change with time, a change in fuel properties, and the like. In particular, the fuel injection pump is provided with a cam plate and a cam roller that come into contact with each other to operate the plunger. Therefore, unless a change over time such as wear due to contact between the cam plate and the cam roller, a change in fuel properties, and the like are taken into account, the fuel injection amount and the fuel injection timing deviate from the desired target values. As a result, there is a possibility that the amount of smoke and the emission of nitrogen oxides (NOx) from the engine may increase.

In view of the above-mentioned problems, Japanese Patent Laid-Open Publication No. Sho 61-283 discloses a technique for prolonging the life of the fuel injection pump by coping with wear of the cam plate and the cam roller.
No. 759. That is, in this conventional technique, parts such as a cam roller that comes into contact with a cam plate (cam disk) of the fuel injection pump are made of sialon ceramics having excellent wear resistance.

[0006]

However, in the above prior art, although the wear between the cam plate and the cam roller is improved, it is difficult to completely eliminate the wear between the cam plate and the cam roller as long as they come into contact with each other. there were. Therefore, after the fuel injection pump is used for a long period of time, unavoidable wear occurs between the cam plate and the cam roller, the lift amount of the plunger changes, and the fuel is pumped from the fuel injection pump to the fuel injection nozzle. The state changes. as a result,
There is a possibility that the fuel injection control is deteriorated and various inconveniences are caused. Further, the properties of the fuel including the fuel viscosity and the like change with the lapse of time after the start of the engine. However, the above-mentioned prior art has not considered this. Therefore, also in that sense, there is a possibility that the state of pumping the fuel from the fuel injection pump to the fuel injection nozzle changes, thereby deteriorating the accuracy of the fuel injection control.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and has as its object to always provide fuel pumping in order to optimize fuel injection in response to aging or fuel property changes in a fuel system. Accurately grasp the condition and send fuel pressure command
It is an object of the present invention to provide a fuel injection device for an internal combustion engine that can determine a value .

[0008]

In order to achieve the above object, in the present invention, as shown in FIG. 1, a fuel injection nozzle M2 which is opened by fuel pressure and injects fuel into an internal combustion engine M1. If, fuel injection pump M3 pumped fuel to the fuel injection nozzle M2 based on the pumping command value
A fuel pressure detecting means M5 for detecting a fuel pressure in the fuel system M4 from the fuel injection pump M3 to the fuel injection nozzle M2; and a start of the fuel pumping from the fuel injection pump M3 to the fuel injection nozzle M2. From the time till the start of injection, a fuel pressure change rate calculating means M6 for calculating a change rate of the fuel pressure based on a detection result of the fuel pressure detecting means M5, and a fuel state detecting means for detecting a state of the fuel M7, a fuel bulk modulus calculating means M8 for calculating the bulk modulus of the fuel based on the detection result of the fuel state detecting means M7, a calculation result of the fuel pressure change rate calculating means M6, and a fuel bulk modulus calculating A fuel leak for calculating a fuel leak rate of the fuel pumped from the fuel injection pump M3 to the fuel injection nozzle M2 based on the calculation result of the means M8.
Rate calculating means M9, based on the calculated fuel leak rate
Command to correct the command value of the fuel injection pump
It is intended to include the correction means M10 .

[0009]

Therefore, according to the above configuration, as shown in FIG. 1, every time fuel is injected from the fuel injection nozzle M2, the fuel pressure in the fuel system M4 is detected by the fuel pressure detecting means M5, The state of the fuel is detected by the state detecting means M7. In the fuel pressure change rate calculating means M6,
The change rate of the fuel pressure is calculated based on the fuel pressure detected as described above. Further, the fuel bulk modulus calculating means M
At 8, the bulk modulus of the fuel is calculated based on the fuel state detected as described above. And the fuel leak rate calculator
In stage M9, fuel leakage definitive fuel system M 4 based on the calculated fuel pressure change rate and the fuel bulk modulus as above
The rate is calculated. Therefore, the fuel leak rate always appropriately reflects the aging change and the fuel property change in the fuel system M4.
Desired. Then, in the pressure feed command correcting means M10,
Based on the determined fuel leakage rate, the fuel injection pump M3
Command value of fuel to be pumped from the pump to the fuel injection nozzle M2
The final fuel injection amount is determined by correcting
You. Therefore, while always grasping the appropriate fuel pumping state,
Appropriate fuel injection can be performed.

[0010]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment in which a fuel injection device for an internal combustion engine according to the present invention is embodied in an electronically controlled diesel engine of an automobile will be described in detail with reference to FIGS.

FIG. 2 shows a schematic configuration of a diesel engine system with a supercharger in this embodiment, and FIG. 3 shows the distribution type fuel injection pump 1. Fuel injection pump 1
Has a drive pulley 2 which is drivingly connected via a belt or the like to a crankshaft 40 of a diesel engine 3 as an internal combustion engine.
Then, the drive pulley 2 is driven by the crankshaft 40.
Is rotated to drive the fuel injection pump 1, whereby fuel is pumped through the fuel pipe 4 a to the fuel injection nozzle 4 provided for each cylinder (four cylinders in this embodiment) of the diesel engine 3.

In this embodiment, the fuel injection nozzle 4 is an automatic valve including a needle valve and a spring for adjusting the valve opening pressure of the needle valve. The valve is opened. Therefore, the fuel injected from the fuel injection pump 1 applies a fuel pressure P equal to or higher than a predetermined level to the fuel injection nozzle 4, whereby fuel is injected from the nozzle 4 to the diesel engine 3.

The fuel injection pump 1 has a drive shaft 5
The drive pulley 2 is attached to the tip of the drive shaft 5. In the middle of the drive shaft 5 is provided a fuel feed pump 6 (developed by 90 degrees in this figure) composed of a vane type pump. A disk-shaped pulsar 7 is attached to the base end side of the drive shaft 5. On the outer peripheral surface of the pulsar 7, missing teeth of the same number as the number of cylinders of the diesel engine 3, that is, four (in total, “eight”) missing teeth are formed at equal angular intervals in this embodiment. Also, between each missing tooth,
Fourteen projections (a total of "56") are formed at equal angular intervals. The base end of the drive shaft 5 is connected to the cam plate 8 via a coupling (not shown).

A roller ring 9 is provided between the pulsar 7 and the cam plate 8. A plurality of cam rollers 10 facing the cam face 8a of the cam plate 8 are mounted in the circumferential direction of the roller ring 9. The cam faces 8 a are provided in the same number as the number of cylinders of the diesel engine 3. The cam plate 8 is a spring 1
1 is urged to engage with the cam roller 10.

A base end of a plunger 12 for pressurizing fuel is attached to the cam plate 8 so as to be integrally rotatable. Then, the cam plate 8 and the plunger 12 are integrally driven to rotate as the drive shaft 5 rotates.
That is, the rotational force of the drive shaft 5 is transmitted to the cam plate 8 via the coupling, so that the cam plate 8 rotates while engaging with the cam roller 10. As a result, the cam plate 8 is reciprocated in the horizontal direction in the drawing by the same number of times as the number of cylinders while being rotated, and the plunger 12 is reciprocated in the same direction while being rotated. That is, the cam face 8a is the cam roller 1 of the roller ring 9.
Plunger 12 moves forward (lift) in the process of climbing to zero
Is done. On the contrary, the cam face 8a is
Plunger 12 moves back in the process of getting over 0 (down)
Is done.

A cylinder 14 is formed in the pump housing 13, and the plunger 12 is fitted into the cylinder 14. A high-pressure chamber 15 is provided between the tip surface of the plunger 12 and the bottom surface of the cylinder 14. In addition, suction grooves 16 and distribution ports 17 are formed on the outer periphery of the distal end side of the plunger 12 by the same number as the number of cylinders. Further, corresponding to the suction groove 16 and the distribution port 17,
A distribution passage 18 and a suction port 19 are formed in the pump housing 13.

In the pump housing 13 of this embodiment, a delivery valve 3 comprising a constant pressure valve (CPV) is provided at the outlet side of each distribution passage 18.
6 are provided. The delivery valve 36 is for preventing a backflow of the fuel pressure-fed from the distribution passage 18 to the fuel pipe 4a, and is opened when a fuel pressure P of a certain level or more is obtained.

When the drive shaft 5 is rotated and the fuel feed pump 6 is driven, fuel is introduced from a fuel tank (not shown) into the fuel chamber 21 through the fuel supply port 20. In the suction stroke in which the plunger 12 is moved back and the high-pressure chamber 15 is depressurized, the suction groove 1
The fuel is introduced from the fuel chamber 21 to the high-pressure chamber 15 when one of the ports 6 communicates with the suction port 19. On the other hand, in the compression stroke in which the plunger 12 is moved forward and the high-pressure chamber 15 is pressurized, fuel is pressure-fed from the distribution passage 18 to the fuel injection nozzle 4 of each cylinder through the fuel pipe 4a and injected.

In the pump housing 13, the high pressure chamber 1
A spill passage 22 for causing fuel to overflow (spill) is formed between the fuel chamber 5 and the fuel chamber 21. An electromagnetic spill valve 23 is provided in the middle of the spill passage 22. The electromagnetic spill valve 23 is opened and closed to adjust the fuel spill from the high-pressure chamber 15. Electromagnetic spill valve 23
Is a normally open valve. When the coil 24 is not energized (off), the spill passage 22 is opened by the valve body 25, that is, the valve is opened, and the fuel in the high-pressure chamber 15 is spilled to the fuel chamber 21. You. On the other hand, when the coil 24 is energized (turned on), the spill passage 22 is closed by the valve body 25, that is, the valve is closed, and the spill of fuel from the high-pressure chamber 15 to the fuel chamber 21 is shut off.

Therefore, when the electromagnetic spill valve 23 is turned on and off by energization, the valve 23 is controlled to close and open, and the spill of fuel from the high-pressure chamber 15 to the fuel chamber 21 is adjusted. When the electromagnetic spill valve 23 is opened during the compression stroke of the plunger 12, the high-pressure chamber 1 is opened.
The fuel in the fuel injection nozzle 4 is depressurized and the fuel injection from the fuel injection nozzle 4 is stopped. That is, even when the plunger 12 moves forward, while the electromagnetic spill valve 23 is opened,
The fuel pressure in the high-pressure chamber 15 does not increase and the fuel injection nozzle 4
Is not injected. Also, during the forward movement of the plunger 12, by controlling the valve opening timing of the electromagnetic spill valve 23, the end timing of the fuel injection from the fuel injection nozzle 4 is adjusted, and the fuel injection amount to the cylinder is controlled. .

Below the pump housing 13, there is provided a timer device (expanded by "90 degrees" in this figure) 26 for controlling the fuel injection timing to the advance side or the retard side. . This timer device 26 changes the rotation position of the roller ring 9 with respect to the rotation direction of the drive shaft 5 to change the timing at which the cam face 8a engages with the cam roller 10, that is, the timing at which the plunger 12 reciprocates. belongs to.

The timer device 26 is driven by control hydraulic pressure, and includes a timer housing 27 and a timer piston 28 fitted in the housing 27. Further, both sides of the timer piston 28 in the timer housing 27 are a low-pressure chamber 29 and a pressurizing chamber 30, respectively. The low-pressure chamber 29 has a timer piston 28
Spring 3 for urging the pressure toward the pressure chamber 30
1 is provided. Further, the timer piston 28 is connected to the roller ring 9 via a slide pin 32.

The fuel pressurized by the fuel feed pump 6 is introduced into the pressurizing chamber 30. The position of the timer piston 28 is determined by the balance between the fuel pressure and the urging force of the timer spring 31. Further, by determining the position of the timer piston 28, the position of the roller ring 9 is determined, and the reciprocating timing of the plunger 12 via the cam plate 8 is determined.

As the control oil pressure of the timer device 26, the fuel pressure inside the fuel injection pump 1 is used. To adjust the fuel pressure, the timer device 26 is provided with a timer control valve (TCV) 33. That is, a communication path 34 is provided between the pressurizing chamber 30 and the low-pressure chamber 29 of the timer housing 27, and the communication path 34
The TCV 33 is provided in the middle of. The TCV 33 is an electromagnetic valve whose opening is controlled by a duty-controlled energization signal. The opening of the TCV 33 is controlled, so that the fuel pressure in the pressurizing chamber 30 is adjusted. Then, by adjusting the fuel pressure, the reciprocating timing of the plunger 12 is controlled.
Is controlled to be advanced or retarded.

On the upper part of the roller ring 9, a rotation speed sensor 35 composed of an electromagnetic pickup coil is mounted so as to face the outer peripheral surface of the pulser 7. This rotation speed sensor 35
Detects the passage of the pulsar when it is crossed by a projection or the like of the pulsar 7 and outputs the signal as a pulse signal. That is, the rotation speed sensor 35 outputs an engine rotation pulse signal for each constant crank angle. At the same time, the rotation speed sensor 35 outputs an engine rotation pulse signal corresponding to a fixed crank angle due to a missing tooth of the pulser 7 as a reference position signal. The rotation speed sensor 35 outputs a series of engine rotation pulse signals as signals for obtaining the engine rotation speed NE.
Since the rotation speed sensor 35 is integrated with the roller ring 9, it can output a reference engine rotation pulse signal at a fixed timing with respect to the reciprocation of the plunger 12 regardless of the control operation of the timer device 26. .

In addition, the pump housing 13 has a fuel temperature sensor 37 as fuel state detecting means for detecting the temperature of the fuel contained in the fuel chamber 21, that is, the fuel temperature THF for detecting the fuel temperature THF. Is provided.

Next, the diesel engine 3 will be described. 2, in the diesel engine 3, a main combustion chamber 44 corresponding to each cylinder is formed by a cylinder bore 41, a piston 42, and a cylinder head 43. In the cylinder head 43, sub combustion chambers 45 communicating with the main combustion chambers 44 are formed. Then, fuel is injected into each sub-combustion chamber 45 from each fuel injection nozzle 4. Each sub-combustion chamber 45 is provided with a well-known glow plug 46 as a start-up assist device.

As shown in FIGS. 2 and 4, each fuel injection nozzle 4 of this embodiment is provided with a pressure sensor 47 as fuel pressure detecting means. The pressure sensor 47 detects the fuel pressure in the fuel system from the fuel injection pump 1 to each fuel injection nozzle 4, that is, the fuel pressure P, and outputs a signal corresponding to the detected value.

On the other hand, the diesel engine 3 is provided with an intake passage 49 and an exhaust passage 50 communicating with each cylinder. Further, a compressor 52 of a turbocharger 51 constituting a supercharger is provided in the intake passage 49,
A turbine 53 of a turbocharger 51 is provided in the exhaust passage 50.
Is provided. Further, a waste gate valve 54 is provided in the exhaust passage 50. As is well known, the turbocharger 51 uses the energy of the exhaust gas to rotate the turbine 53, and rotates the compressor 52 coaxially therewith to increase the pressure of the intake air. Then, by increasing the pressure of the intake air, high-density air is sent into the main combustion chamber 44 and a large amount of fuel injected through the sub-combustion chamber 45 is burned, so that the output of the diesel engine 3 is increased. The opening and closing of the waste gate valve 54 causes the turbocharger 5 to open and close.
The boost pressure level of the intake air by 1 is adjusted.

Between the intake passage 49 and the exhaust passage 50,
Exhaust gas recirculation valve passage (EG
An R path 56 is provided. Then, a part of the exhaust gas in the exhaust passage 50 is recirculated by the EGR passage 56 near the intake port 55 in the intake passage 49.
An EGR valve 57 is provided in the middle of the EGR passage 56, and the EGR valve 57 controls the exhaust gas recirculation amount (E
GR amount) is adjusted. Further, in order to open and close the EGR valve 57, an electric vacuum regulating valve (EVRV) 58 whose opening is adjusted is controlled.
Is provided. Then, EGRV58 is used for EGR
When the valve 57 is driven to open and close, the EGR passage 5
E guided from the exhaust passage 50 to the intake passage 49 through
The GR amount is adjusted.

A throttle valve 59 is provided in the middle of the intake passage 49. The throttle valve 59 is opened and closed in conjunction with depression of an accelerator pedal 60. In the intake passage 49,
A bypass passage 61 is provided alongside the throttle valve 55, and a bypass throttle valve 62 is provided in the passage 61. In order to open and close the bypass throttle valve 62, a two-stage diaphragm chamber type actuator 63 is provided. Also, two vacuum switching valves (VS) for driving the actuator 63 are provided.
V) 64, 65 are provided. And each VSV6
The bypass throttle valve 62 is controlled to open and close by driving the actuator 63 with the on / off control of the valves 4 and 65. For example, the bypass throttle valve 62 is controlled to be in a half-open state in order to reduce noise and vibration during idling operation, is controlled to be in a fully open state in normal operation, and is controlled to be in a fully closed state in order to smoothly stop the operation. Is done.

In the vehicle of this embodiment, the driver's seat is provided with a warning lamp 66 which is turned on to notify the driver of a deterioration abnormality of the fuel injection device including the fuel injection pump 1 and the fuel injection nozzle 4. ing. The warning lamp 66 is turned on as a result of an abnormality diagnosis described later.

The above-described electromagnetic spill valve 23, TCV3
3, glow plug 46, EVRV58, each VSV64,
The electronic control unit (hereinafter simply referred to as “E”)
CU ”) 71. And each of these members 23, 33, 46, 58, 6
The drive timings of 4, 65, 66 are controlled by the ECU 71.

As sensors for detecting the operating state of the diesel engine 3, in addition to the rotation speed sensor 35 described above, the following various sensors are provided. That is, near the air cleaner 67 provided at the entrance of the intake passage 49, the temperature of the air taken into the intake passage 49, that is, the intake air temperature THA is detected, and a signal corresponding to the detected value is output. An intake air temperature sensor 72 is provided. In the vicinity of the throttle valve 59, there is provided an accelerator sensor 73 which detects an accelerator opening ACCP corresponding to the engine load from the open / close position of the valve 59 and outputs a signal corresponding to the magnitude of the detected value. I have. In the vicinity of the intake port 55, an intake pressure sensor 74 that detects the pressure of the intake air after being supercharged by the turbocharger 51, that is, the supercharging pressure PiM, and outputs a signal corresponding to the magnitude of the detected value. Is provided. Further, the diesel engine 3 is provided with a water temperature sensor 75 which detects the temperature of the cooling water, that is, the cooling water temperature THW, and outputs a signal corresponding to the magnitude of the detected value. Further, the diesel engine 3 is provided with a crank angle sensor 76 that detects a rotation reference position of the crankshaft 40, for example, a rotation position of the crankshaft 40 with respect to a top dead center of a specific cylinder, and outputs a signal corresponding to the rotation position. Have been. Further, a transmission (not shown) is provided with a vehicle speed sensor 77 for detecting a vehicle speed (vehicle speed) SPD. This vehicle speed sensor 7
Reference numeral 7 includes a magnet 77a rotated by an output shaft of the transmission, and a reed switch 77b is periodically turned on by the magnet 77a to output a pulse signal corresponding to the vehicle speed SPD.

In this embodiment, the ECU 71 constitutes a fuel pressure change rate calculating means, a fuel bulk elasticity calculating means and a fuel pumping state value calculating means. And
The above-described sensors 72 to 77, the rotation speed sensor 35, the fuel temperature sensor 37, and the pressure sensor 47 are connected to the ECU 71, respectively. In addition, the ECU 71 controls the sensors 35, 3
7, 47, based on each signal output from 72 to 77,
Electromagnetic spill valve 23, TCV 33, glow plug 46, E
The VRV 58, the VSVs 64 and 65, the warning lamp 66, and the like are suitably controlled.

Next, the configuration of the ECU 71 will be described with reference to the block diagram of FIG. The ECU 71 includes a central processing unit (CPU) 81, a read-only memory (ROM) 82 in which a predetermined control program, a map, and the like are stored in advance,
A random access memory (RAM) 83 for temporarily storing the calculation results of the PU 81, a backup RAM 84 for storing the stored data, and the like are provided. And ECU
Reference numeral 71 denotes a logical operation circuit in which these units 81 to 84 are connected to an input port 85, an output port 86, and the like via a bus 87.

The input port 85 is provided with the above-described intake air temperature sensor 72, accelerator sensor 73, intake air pressure sensor 74, water temperature sensor 75, pressure sensor 47, and fuel temperature sensor 37 in the buffers 88, 89, 90, 91, 92. , 93, a multiplexer 94 and an A / D converter 95. Similarly, the input port 85 includes the above-described rotation speed sensor 35, crank angle sensor 76, and vehicle speed sensor 77.
Are connected via a waveform shaping circuit 96. Then, the CPU 81 reads, as input values, signals from the sensors 35, 37, 47, 72 to 77, etc., which are input via the input port 85. The output ports 86 are connected to the respective drive circuits 97, 98, 99, 100, 101, 10
The electromagnetic spill valve 23, the TCV 33, the glow plug 46, the EVRV 58, the VSVs 64 and 65, the warning lamp 66, and the like are connected through the components 2 and 103, respectively. Then, the CPU 81 controls each of the sensors 35, 37, 47, 72-7.
Spill valve 2 based on the input value read from
3, the TCV 33, the glow plug 46, the EVRV 58, the VSVs 64 and 65, the warning lamp 66, and the like are suitably controlled.

In this embodiment, the CPU 81 has a timer function. Also, in this embodiment,
The glow plug 46 and the pressure sensor 47 are provided for each cylinder of the diesel engine 3.
Only one of them is shown in the block diagram of FIG.

Next, the contents of processing for fuel injection control and the like executed by the ECU 71 will be described.
FIG. 6 shows a “fuel pressure processing routine” that is periodically executed at predetermined time intervals among the processing executed by the ECU 71.
It is a flowchart which shows.

When the process proceeds to this routine, first, at step 110, a control flag F for detecting pressure is set.
Reset L to "0". Subsequently, in step 111, the value of the fuel pressure P is sampled based on the signal from the pressure sensor 47.

Next, at step 112, it is determined whether or not the control flag FL is "0". Here, if the control flag FL is not “0”, the process proceeds to step 120. If the control flag FL is “0”, the process proceeds to step 113.

Then, in step 113, it is determined whether or not the value of the fuel pressure P sampled this time is equal to or more than the reference value P1 immediately after the start of the fuel pumping from the fuel injection pump 1. Here, if the value of the fuel pressure P is not equal to or more than the reference value P1, the process jumps to step 111 and repeats the processing of steps 111 to 113. If the value of the fuel pressure P is equal to or higher than the reference value P1, step 1
Move to 14. Then, in step 114, the control flag FL is set to "1". Step 11
In step 5, after resetting the pointer data i to "0", the routine jumps to step 111 and proceeds to the processing after step 111.

On the other hand, after step 112, in step 120, it is determined whether or not the control flag FL is "1". Here, if the control flag FL is not “1”, the process proceeds to step 160. Control flag F
When L is “1”, the process proceeds to step 121.

In step 121, it is determined whether or not the value of the fuel pressure P sampled this time is smaller than a reference value P2 immediately before the fuel pumped from the fuel injection pump 1 is injected from the fuel injection nozzle 4. . Here, if the value of the fuel pressure P is not smaller than the reference value P2, the process proceeds to step 130. When the value of the fuel pressure P is smaller than the reference value P2, the process proceeds to step 122.

In step 122, the pointer data i is incremented by "1". In step 123, the value of the fuel pressure P sampled this time is stored in the RAM 83 as the value of the fuel pressure P (i) corresponding to the current pointer data i.
The process jumps to step 11 and proceeds to the processing after step 111.

On the other hand, the process proceeds from step 121 to step 130, where the increment of the pointer data i ends. That is, the current pointer data i is set to the maximum value n.

In step 140, the average fuel pressure change rate AdP is calculated. That is, as shown in the flowchart of the "average fuel pressure change rate calculation routine" in FIG. 7, first, in step 141, the accumulated value TdP of the value of the fuel pressure change rate dP described later is reset to "0". In step 142, the pointer data i is set to "1".

Subsequently, in step 143, the RAM
The fuel pressure change rate dP is calculated based on the values of the plurality of fuel pressures P (i) to P (n) stored in 83.
That is, the fuel pressure change rate dP is obtained according to the following equation (1).

DP = {P (i + 1) −P (i−1)} / 2 (1) Next, at step 144, the accumulated value T up to the previous time is
The fuel pressure change rate dP obtained this time is added to dP to obtain a new accumulated value TdP.

In step 145, the pointer data i is incremented by "1". Further, in step 146, the value of the pointer data i becomes the maximum value n
Determine if it is greater than. Here, when the value of the pointer data i is not larger than the maximum value n, the fuel pressure P
It is assumed that the fuel pressure change rate dP has not been obtained for all the values of (i) to fuel pressure P (n),
Then, the processing jumps to step 143 to step 146 and is repeated. If the value of the pointer data i is larger than the maximum value n, it is determined that the fuel pressure change rate dP has been obtained for all the fuel pressures P (i) to P (n), and the process proceeds to step 147. .

In step 147, the average fuel pressure change rate AdP is calculated based on the accumulated value TdP.
That is, the average fuel pressure change rate AdP is obtained according to the following equation (2).

AdP = TdP / n (2) After calculating the average fuel pressure change rate AdP, the process is performed as shown in FIG.
To step 150.

Then, in step 150, after setting the control flag FL to "2", the routine jumps to step 111 and proceeds to the processing after step 111. on the other hand,
In step 160 after shifting from step 120, it is determined whether the value of the fuel pressure P sampled this time is smaller than a reference value P3 immediately after fuel injection from the fuel injection nozzle 4. Here, the value of the fuel pressure P is equal to the reference value P.
If the value is not smaller than 3, the process jumps to step 111 and proceeds to the process after step 111. If the value of the fuel pressure P is smaller than the reference value P3, step 1
At 61, after resetting the control flag FL to "0", the routine jumps to step 111 and proceeds to the processing after step 111.

Here, the execution of the above "fuel pressure processing routine" will be described with reference to the time chart of FIG. This time chart shows the behavior of the fuel pressure P during one fuel injection. As can be seen from this time chart, the average fuel pressure change rate AdP is obtained while the fuel pressure P changes from the reference value P1 to the reference value P2 in a section from the start of fuel pumping to the start of fuel injection. The average fuel pressure change rate AdP obtained in this manner is obtained as an actual measurement value reflecting a temporal change, a fuel property, and the like in the fuel system including the fuel injection pump 1 and the fuel injection nozzle 4 at the time of fuel injection.

In this embodiment, the following control regarding fuel injection is executed using the average fuel pressure change rate AdP obtained as described above. That is, FIG.
Is a flowchart showing the processing content of a "fuel injection control routine" executed by the ECU 71, and is periodically executed at predetermined time intervals.

When the processing shifts to this routine, first, in step 201, various sensors 35, 37, 73-
Engine speed N based on various signals from
E, fuel temperature THF, accelerator opening ACCP, boost pressure P
Each value such as iM and cooling water temperature THW is read.
Further, the average fuel pressure change rate AdP obtained by the "average fuel pressure change rate calculation routine" is read.

Subsequently, at step 202, the currently read engine speed NE and accelerator opening ACC are read.
P, supercharging pressure PiM and cooling water temperature THW
The target injection amount Q corresponding to the current operation state is calculated according to a predetermined calculation formula.

In step 203, the engine speed NE, the accelerator opening ACCP, and the supercharging pressure Pi are similarly determined.
Based on the values of M and the coolant temperature THW, a target injection timing Ti corresponding to the current operation state is calculated according to a predetermined calculation formula.

Further, in step 204, based on the value of the target injection amount Q obtained this time and the value of the engine speed NE, the engine speed N
A period during which the fuel injection nozzle 4 should be opened, that is, an injection period Tau, is calculated according to the magnitude of E.

Next, at step 205, the fuel bulk elasticity AE is calculated based on the fuel temperature THF read this time. The fuel bulk modulus AE is obtained by referring to a predetermined map as shown in FIG. In this map, the fuel bulk modulus AE is set to decrease as the fuel temperature THF increases.

Subsequently, in step 206, the fuel leakage rate QL as the fuel pumping state value in the fuel system is calculated based on the average fuel pressure change rate AdP and the fuel bulk modulus AE obtained as described above. I do. Here, in general, when there is a fuel leak in the fuel system, the fuel pressure change rate from the start of fuel pumping to the start of injection is defined by the following principle.

DP = AE * (QP−QL) / V (3) In this principle formula (3), “QP” is an oil feed rate when fuel is pumped from the fuel injection pump 1, and “V "Is a volume in the fuel system between the fuel injection pump 1 and the fuel injection nozzle 4, and is a design value which can be obtained in advance.

Accordingly, by applying the average fuel pressure change rate AdP to the fuel pressure change rate dP from the above-mentioned principle equation (3), the fuel leakage rate QL can be obtained according to the following formula (4).

QL = QP−AdP * V / AE (4) Here, when the average fuel pressure change rate AdP is small or the fuel bulk modulus AE is small, the fuel leakage rate Q
It turns out that L becomes large.

In step 207, the injection timing correction value ΔTi is determined based on the fuel leakage rate QL and the like obtained this time.
Is calculated. The injection timing correction value ΔTi is obtained according to the following equation (5). In this equation (5), “KT”
Is a constant determined in advance.

ΔTi = −KT * QL (5) That is, as can be seen from the equation (5), the injection timing correction value ΔTi is calculated when fuel leakage occurs in the fuel system.
This is a value required to compensate the injection timing Ti by the fuel leakage rate QL.

Further, in step 208, an injection period correction value ΔTau is calculated based on the target injection amount Q, injection period Tau, fuel leakage rate QL, etc. obtained as described above.
The injection period correction value ΔTau is obtained according to the following equation (6).

ΔTau = Tau * QL / {(Q / Tau) −QL} (6) That is, as can be seen from the calculation formula (6), the injection period correction value ΔTau indicates that the fuel leakage in the fuel system occurs. If there is, this is a value obtained for compensating the injection period Tau by the fuel leakage rate QL.

In step 209, a final injection timing command value TiF is calculated according to the following equation (7) based on the target injection timing Ti and the injection timing correction value ΔTi obtained as described above.

TiF = Ti + ΔTi (7) In step 210, based on the injection period Tau, the injection period correction value ΔTau, and the injection timing command value TiF obtained as described above, the following formula (8) is used. ,
A final spill timing command value Tsp corresponding to the fuel injection end timing is calculated.

Tsp = TiF + Tau + ΔTau (8) In step 211, injection timing control is executed based on the injection timing command value TiF obtained this time.
That is, by controlling the TCV 33 based on the injection timing command value TiF and controlling the timer device 26, the timing of pumping the fuel from the fuel injection pump 1 to the fuel injection nozzle 4 is adjusted. It controls the injection timing.

In step 212, the fuel injection amount control is executed based on the spill timing command value Tsp obtained this time, and the subsequent processing is temporarily terminated. That is, by controlling the electromagnetic spill valve 23 based on the spill timing command value Tsp, the pressure of fuel from the fuel injection pump 1 to the fuel injection nozzle 4 is controlled, thereby controlling the fuel injection amount from the fuel injection nozzle 4. . The fuel injection control is executed as described above.

On the other hand, in this embodiment, the following fuel system abnormality diagnosis processing is executed using the fuel leakage rate QL obtained as described above. That is, FIG.
2 is a flowchart showing the processing content of a “fuel system diagnosis routine” executed by Step 1 and is executed periodically at predetermined time intervals.

When the process proceeds to this routine, first, at step 310, the value of the fuel leakage rate QL obtained in the above-mentioned "fuel injection control routine" is read. Subsequently, in step 320, it is determined whether or not the value of the fuel leakage rate QL read this time is larger than a predetermined reference value α. Here, when the value of the fuel leakage rate QL is not larger than the reference value α, it is determined that the change with time or the fuel property of the fuel system is not unnecessarily large, and the subsequent processing is temporarily terminated. On the other hand, the fuel leakage rate QL
Is larger than the reference value α, it is determined that the fuel system has changed over time or the fuel property is excessive and the fuel system is abnormal, and the process proceeds to step 330.

At step 330, the warning lamp 66 is turned on to notify the driver of the abnormality of the fuel system. Also, in step 340, a fuel system abnormality diagnostic code for indicating that there is an abnormality in the fuel system is stored in the backup RAM 84, and the subsequent processing is temporarily terminated. Thus, the abnormality diagnosis of the fuel system is performed.

As described above, according to the fuel injection control of this embodiment, every time one fuel injection is executed, the change over time in the fuel system from the fuel injection pump 1 to the fuel injection nozzle 4 and The fuel leakage rate QL reflecting the change in the fuel properties and the like is obtained as an actually measured value. Also, the fuel leakage rate QL
The spill timing command value Tsp and the injection timing command value TiF corrected on the basis of are obtained. Then, based on the spill timing command value Tsp and the injection timing command value TiF,
The drive of the fuel injection pump 1 is controlled to execute the fuel injection amount control and the fuel injection timing control.

Therefore, in each fuel injection, the amount of fuel pumped from the fuel injection pump 1 to the fuel injection nozzle 4 includes a fuel pumping state caused by a temporal change in the fuel system and a change in fuel properties such as fuel viscosity. That is, the change in the fuel leakage rate QL is corrected, and the influence of the fuel leakage rate QL is eliminated. For this reason, the desired amount of fuel can be fed under pressure to the fuel injection nozzle 4 and injected without being affected by changes over time or changes in fuel properties in the fuel system. Similarly, fuel can be injected from the fuel injection nozzle 4 at a desired injection start timing.

As a result, high-precision fuel injection amount control and fuel injection timing control can always be stably performed in response to temporal changes and fuel property changes in the fuel system. For example, even if abrasion occurs between the cam plate 8 and the cam roller 10 in the fuel injection pump 1 to change the stroke absolute amount of the plunger 12 or change the fuel viscosity, the change in the fuel is taken into account. Injection control can be performed with high accuracy. As a result, the emission of smoke and nitrogen oxides (NOx) from the diesel engine 3 can be suppressed. Further, in this embodiment, in the fuel system from the fuel injection pump 1 to the fuel injection nozzle 4, the fuel pressure P in the pressure increasing process immediately before the fuel injection nozzle 4 is opened, that is, immediately before the start of fuel injection, is detected. The average fuel pressure change rate AdP is obtained based on the value of the fuel pressure P. Further, the fuel bulk modulus AE is obtained based on the fuel temperature THF at that time. Then, based on the average fuel pressure change rate AdP and the fuel bulk modulus AE, a fuel leakage rate QL reflecting the fuel pumping state in the fuel system is obtained.

Therefore, in each fuel injection, an appropriate fuel leakage rate QL reflecting a temporal change and a change in fuel properties is measured from the fuel pressure P and the fuel temperature THF actually detected in the fuel system. Can be obtained as a value. That is, the state of fuel pumping can always be accurately grasped. Moreover, the average fuel pressure change rate AdP can reflect various conditions of the entire fuel system.

As a result, the environmental condition in the fuel system is more accurately grasped from the average fuel pressure change rate Adp, and the injection timing correction value ΔTi and the injection period correction value Δ
Tau can be determined. Also, their respective correction values Δ
Based on Ti, ΔTau, more accurate injection timing command value T
iF and the spill timing command value Tsp can be obtained. In this sense, the fuel injection amount control and the fuel injection timing control can be performed with higher accuracy.

In addition, in this embodiment, the fuel leakage rate QL
When it is determined that the fuel system is abnormal based on the above, the warning lamp 66 is turned on, so that the driver can be notified of the abnormality of the fuel system in real time. or,
Since the diagnostic code relating to the abnormality of the fuel system is stored in the backup RAM 84, it is possible to confirm the presence or absence of the abnormality of the fuel system by reading the data of the backup RAM 84 at the time of periodic inspection of the engine or the like. .

It should be noted that the present invention is not limited to the above-described embodiment, and may be implemented as follows, with a part of the configuration being appropriately changed without departing from the spirit of the invention. (1) In the above embodiment, the fuel leakage rate QL reflecting the fuel pumping state is obtained based on the average fuel pressure change rate AdP obtained from the fuel pressure P and the fuel bulk modulus AE obtained from the fuel temperature THF. The injection timing command value TiF and the spill timing command value Tsp are corrected based on the fuel leakage rate QL. On the other hand, based on the average fuel pressure change rate AdP and the fuel bulk modulus AE, the fuel leakage rate Q
Instead of L, an oil feed rate reflecting the fuel pumping state may be obtained, and the injection timing command value TiF and the spill timing command value Tsp may be corrected based on the oil feed rate.

(2) In the above embodiment, the fuel leakage rate QL is determined based on the average fuel pressure change rate AdP and the fuel bulk modulus AE, and the injection timing correction value ΔTi and the injection period are determined based on the fuel leakage rate QL. The correction value ΔTau was determined. On the other hand, in order to prevent the effects of noise and errors in the correction values ΔTi and ΔTau, the correction values ΔTi and ΔTau may be obtained from a weighted average of a plurality of past calculation data.

(3) In the above embodiment, the average fuel pressure change rate AdP is obtained by averaging the accumulated values TdP of the plurality of fuel pressure change rates dP obtained from the start of fuel pumping to the start of injection. Was. On the other hand, the fuel pressure change rate dP at a certain pressure point between the start of fuel pumping and the start of injection is calculated every time, and the average of the values of the fuel pressure change rate dP in the past multiple times at that pressure point is averaged. The fuel pressure change rate AdP may be obtained. Alternatively, the average fuel pressure change rate AdP may be determined by learning control.

(4) In the above embodiment, the injection timing command value TiF and the spill timing command value Tsp are corrected based on the fuel leakage rate QL obtained based on the average fuel pressure change rate AdP and the fuel bulk modulus AE. I did it. On the other hand, based on the fuel leakage rate QL obtained based on the average fuel pressure change rate AdP and the fuel bulk modulus AE, the EGR
And the like may be corrected.

(5) In the above-described embodiment, the fuel leakage rate QL obtained every time in the entire operation range of the diesel engine 3
The fuel injection timing command value TiF and the spill timing command value Tsp were corrected based on the above, and the diagnosis of the fuel system abnormality was performed. On the other hand, the injection timing command value TiF and the spill timing command value Tsp in the entire operation range are corrected based on the fuel leakage rate QL obtained only when the diesel engine 3 is running at a low speed, and a diagnosis of a fuel system abnormality is performed. Or you may. In this case, the fuel leakage rate QL increases as the diesel engine 3 rotates at a lower speed, and can be obtained as an accurate value. As a result, it becomes possible to correct the injection timing command value TiF and the spill timing command value Tsp and to diagnose the fuel system abnormality more accurately.

(6) In the above embodiment, the pressure sensor 47 for detecting the fuel pressure P is provided in the fuel injection nozzle 4, but the pressure sensor is provided corresponding to the high pressure chamber of the fuel injection pump, It may be provided in the middle of the fuel pipe leading to the nozzle.

(7) In the above embodiment, the diesel engine 3 is used as the internal combustion engine. However, any internal combustion engine having a fuel injection device having a fuel injection pump and a fuel injection nozzle is limited to the diesel engine. Not something.

[0089]

As described above in detail, according to the present invention, in the fuel system from the fuel injection pump to the fuel injection nozzle, based on the fuel pressure detected from the start of the fuel pumping to the start of the fuel injection. Find the fuel pressure change rate. Also, the fuel bulk modulus is determined based on the fuel state. Then, a fuel leakage rate is determined based on the fuel pressure change rate and the fuel bulk modulus. Therefore, always accurate fuel leakage
It is possible to grasp the rate, and it is possible to obtain an excellent effect that the fuel injection can be appropriately performed by coping with the temporal change and the change of the fuel property in the fuel system.

[Brief description of the drawings]

FIG. 1 is a conceptual configuration diagram illustrating a basic conceptual configuration of the present invention.

FIG. 2 is a schematic diagram showing a supercharged diesel engine system according to an embodiment of the present invention.

FIG. 3 is a sectional view showing a distribution type fuel injection pump in one embodiment.

FIG. 4 is a side view showing a fuel injection nozzle in one embodiment.

FIG. 5 is a block diagram showing a configuration of an ECU in one embodiment.

FIG. 6 is a flowchart illustrating a “fuel pressure processing routine” executed by an ECU in one embodiment.

FIG. 7 is a flowchart showing an “average fuel pressure change rate calculation routine” executed by the ECU in one embodiment.

FIG. 8 is a time chart showing a behavior of a fuel pressure in one fuel injection and a calculation section of an average fuel pressure change rate at that time in one embodiment.

FIG. 9 is a flowchart showing a “fuel injection control routine” executed by the ECU in one embodiment.

FIG. 10 is a map showing a relationship between fuel temperature and fuel bulk modulus in one embodiment.

FIG. 11 is a flowchart showing a “fuel system diagnosis routine” executed by the ECU in one embodiment.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Fuel injection pump, 3 ... Diesel engine as an internal combustion engine, 4 ... Fuel injection nozzle, 37 ... Fuel temperature sensor (3
7 constitutes a fuel state detecting means), 47 ... pressure sensor (47 constitutes a fuel pressure detecting means), 71 ...
The ECU 71 constitutes a fuel pressure change rate calculating means, a fuel bulk modulus calculating means, and a fuel pumping state value calculating means.

──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Takehiko Hirose 1 Toyota Town, Toyota City, Aichi Prefecture Inside Toyota Motor Corporation (72) Inventor Akira Shibata 1-1 1-1 Showa Town, Kariya City, Aichi Prefecture Nihon Denso Co., Ltd. (72) Inventor Teiji Inakuma 1-1-1, Showa-cho, Kariya-shi, Aichi, Japan Denso Co., Ltd. (72) Inventor Kenzo Yano 1-1-1, Showa-cho, Kariya-shi, Aichi Nihon Denso Co., Ltd. Tatsuya Ichikawa 1-1-1, Showa-cho, Kariya-shi, Aichi Japan Nippon Denso Co., Ltd. (56) References JP-A-64-63650 (JP, A) JP-A-4-50460 (JP, A) (58) Fields investigated (Int.Cl. ⁶ , DB name) F02D 41/00-45/00

Claims (1)

(57) [Claims] 1. A fuel injection nozzle for injecting fuel is opened by the fuel pressure to the internal combustion engine, fuel injection pump you pumped <br/> fuel to the fuel injection nozzle based on the pumping command value A fuel pressure detecting means for detecting a fuel pressure in a fuel system from the fuel injection pump to the fuel injection nozzle; and a fuel injection from the fuel injection pump to the fuel injection nozzle. A fuel pressure change rate calculating means for calculating a change rate of the fuel pressure based on a detection result of the fuel pressure detecting means; a fuel state detecting means for detecting a state of fuel; A fuel bulk modulus calculating unit for calculating a bulk modulus of the fuel based on a detection result of the fuel state detecting unit; a calculation result of the fuel pressure change rate calculating unit and the fuel bulk modulus calculating Based on the calculation results of the step, leakage fuel in the fuel pumped to the fuel injection nozzle from the fuel injection pump
Fuel leak rate calculating means for calculating the fuel leak rate, and the fuel injection pump based on the calculated fuel leak rate.
A fuel injection command value correcting means for correcting the pressure command value of the pump .