JPS6226341A - Fuel injection control method for diesel engine - Google Patents

Abstract

PURPOSE:To suppress the idle vibration by driving a timer control valve for controlling the fuel injection timing with the ordinary driving frequency in the ordinary operation state other than in idling and driving said control valve with the driving frequency higher than the ordinary value in the operation state in idling or in the vicinity of idling. CONSTITUTION:In a fuel injection pump 42, the fuel injection quantity is controlled by controlling an electromagnetic spill valve 50 according to an aimed spill timing determined on the basis of the signal which is synchronized with the lift of the plunger 42G and input at each prescribed pump angle and the engine revolution speed. Further, the fuel injection timing is controlled by duty- controlling a timer control valve 48. In this case, when the normal operation state other than in idling or in the vicinity of idling is judged from each output of an accelerator position sensor 20, shift position sensor, or the like, the timer control valve 48 is driven with the ordinary driving frequency, and while, in the operation state of idling or in the vicinity of idling, the timer control valve 48 is driven with the driving frequency higher than the ordinary value.

Description

[Detailed description of the invention] [Industrial application field]

The present invention relates to a fuel injection control method for a diesel engine, and is particularly suitable for use in an automatic heavy-duty electronically controlled diesel engine using a solenoid valve spill type fuel injection pump, and is synchronized with the plunger lift of a fuel injection pump. In addition, based on the spill timing determined by converting the angle into time from the signal input for each predetermined pump color and the engine rotation speed, the fuel injection amount is controlled by on/off control with the electromagnetic spill valve. The present invention relates to an improvement in a fuel injection control method for a diesel engine in which fuel injection timing is controlled by on/off duty control of a timer control valve.

[Conventional technology]

In recent years, with the development of electronic control technology, particularly digital control technology, so-called electronically controlled diesel engines, in which the fuel injection pump of a diesel engine is electronically controlled, have been put into practical use. There are various methods of electronically controlling a fuel injection pump, and one of them is a so-called [41 spill type fuel injection pump] in which the spill of fuel in the fuel injection pump is controlled by a solenoid valve. In this electromagnetic spill type fuel injection pump, when the fuel injection amount reaches the target value, i
f... The fuel injection timing is controlled by opening the spill boat with the spill valve and controlling the end of pressure feeding of the fuel. In such a Ti electromagnetic spill fuel injection pump, normally, as shown in FIG. The target spill timing is determined by converting the target spill angle into time based on the average engine rotation speed, and based on the target spill timing, 1
The f11 spill valve is controlled to be turned on and off. Further, the fuel injection timing is controlled by on/off duty control of a timer control valve that controls a timer piston that engages with a roller ring.

[Problems to be solved by the invention]

However, as shown in FIGS. 8 and 9, the NE pulse is usually generated by an engine rotating pulser (hereinafter referred to as NE pulser) which is press-fitted into the pump drive shaft 42A and has a gear and its missing teeth on the outer periphery. ) 42E and roller 421
The plunger 4
When 2G lifts, the roller ring 42H is slightly rotated in the driving direction due to the reaction force from the face cam 42F transmitted via the roller 421, causing the synchronization between the time conversion amount and the plunger lift to deviate. , as shown in FIG.
This causes the phenomenon that the data is spilled to the second party. Note that if such a phenomenon is a regular occurrence, it can be countered by, for example, changing the target spill time itself in advance, and no actual damage will occur. On the other hand, as shown in FIG. 8, the timer piston 42J that engages with the roller ring 42H has a piston end surface (
The high fuel pressure applied to the roller ring 42H (in the figure, the left end face) is changed by on/off duty control of the timer control valve (hereinafter referred to as TCV) 48.
is rotated to determine the target injection timing. However, if the frequency at which this TCV 48 is driven is small, the on time, that is, the voltage release time each time becomes long, and the 11th
As shown in the above, when the on-time coincides with the plunger lift time, that is, when the face cam reaction force and the on-time coincide, the above-mentioned deviation in the spill timing becomes larger,
Since the injection amount fluctuates unsteadily and becomes irregular, there was a problem in that vibrations could worsen, especially in areas where the influence of the injection amount is easily reflected in the rotation speed, such as during idling. . In order to solve these problems, it is conceivable to uniformly increase the drive frequency of the TCV 48, but in this case, the number of times the TCV 48 operates increases dramatically,
There was a problem in that the lifespan of TCV48 was shortened, which was unfavorable in terms of reliability.

OBJECTIVE OF THE INVENTION 1 The present invention has been made in order to solve the above-mentioned problems of the conventional art, without significantly shortening the life of the timer control valve.
It is an object of the present invention to provide a fuel injection control method for a diesel engine that can suppress irregularities in injection amount to a level that does not worsen idle 1st movement. [Means for Solving the Problems 1] The present invention determines the target spill angle by converting it into time from a signal and engine rotation speed that are synchronized with the plunger lift of the fuel injection pump and are input for each predetermined pump color. Fuel injection of a diesel engine in which the fuel injection amount is controlled by on/off control of an electromagnetic spill valve based on the target spill timing, and the fuel injection timing is controlled by on/off duty control of a TCV. As shown in FIG. 1, the control method includes a procedure for detecting idle and near-idle operating conditions, and a normal operating state other than idle or near-idle.
This objective is achieved by including a procedure for driving the lower CV at a normal drive frequency, and a procedure for driving the TCV at a higher than normal drive frequency during idle and near-idle operating conditions. Further, in an embodiment of the present invention, the operating state near the idle is in the neutral range and the accelerator opening is at a predetermined tI.
The operating state is below tI. Furthermore, in an embodiment of the present invention, hysteresis is provided in the accelerator opening degree when switching the drive frequency. In another embodiment of the present invention, the drive frequency higher than normal is an integral multiple of the normal drive frequency. [Function] In the present invention, synchronization with the plunger lift of the fuel injection pump and based on the signal input for each predetermined pump color and the engine rotation speed, the target spill timing is determined by converting one tank spill angle into time. Based on 1! The fuel injection amount is controlled by on/off control of the spill valve, and
When controlling the fuel injection timing by on/off duty control of the TCV, the TCv is controlled at a higher driving frequency than normal in idle and near-idle operating conditions.
I like to drive. Therefore, the shift in the spill timing is not exacerbated at idle and near idle, where there is a risk of deterioration in one-stroke motion, and it is possible to prevent deterioration in idle photography. In addition, in normal operating conditions other than idle or near idle, TCV
Since the TCV is driven, the number of times the TCV operates can be kept to the minimum necessary, and the number of times the TCV operates does not increase significantly and its lifespan will not be completely exhausted. Furthermore, when the operating state near the idle is set to a neutral range and the accelerator opening is below a predetermined value, it is possible to quickly switch the frequency during no-load racing, where the influence of irregular injection is less likely to occur. This is advantageous in terms of reliability. Further, when the accelerator opening degree is provided with hysteresis when switching the drive frequency, the drive frequency is not switched more frequently than necessary. Furthermore, when the drive frequency higher than normal is an integral multiple of the normal drive same wave number, the control logic is simple.

[Embodiment 1] Hereinafter, an embodiment of an electronically controlled diesel engine for automatic heavy duty, in which the fuel injection control method according to the present invention is adopted, will be described in detail with reference to the drawings. As shown in FIG. 2, this embodiment includes an intake air temperature sensor 12 disposed downstream of an air cleaner (not shown) for detecting the temperature of intake air. A turbocharger 14 is provided downstream of the intake air temperature sensor 12 and includes a turbine 14A rotated by thermal energy of exhaust gas and a compressor 14B rotated in conjunction with the turbine 14A. A waste gate valve 1 is provided on the upstream side of the turbine 14A of the turbocharger 14 and on the downstream side of the compressor 14B to prevent excessive rise in intake pressure.
5. The venturi 16 downstream of the compressor 14B includes:
A main intake control valve 18 is provided, which is configured to rotate non-linearly in conjunction with an accelerator pedal 17 disposed on the driver's seat, in order to limit the flow rate of intake air during idle, etc. . The opening degree (referred to as accelerator opening degree) Accp of the accelerator pedal 17 is detected by an accelerator position sensor 20 . A sub-intake proofing valve 22 is provided in parallel with the main intake proofing valve 18, and the opening degree of the sub-intake proofing valve 22 is controlled by a diaphragm device 24. The diaphragm device 24 receives the negative pressure generated by the negative pressure pump 26.
Negative pressure switching valve (hereinafter referred to as VSV) 28 or 30
Supplied via. An intake pressure sensor 32 for detecting the pressure of intake air is provided downstream of the intake throttle valve 18.22. In the cylinder head 10A of the diesel engine 10,
An injection nozzle 34 whose tip faces the engine combustion chamber 10B, a glow plug 36, and an ignition timing sensor 38 are provided. Further, the cylinder block 10C of the diesel engine 10 is equipped with a water temperature sensor 40 for detecting the engine cooling water temperature. Fuel is fed under pressure to the injection nozzle 34 from an injection pump 42 . The injection pump 42 includes a pump drive shaft 42Δ that rotates in conjunction with the rotation of the crankshaft of the diesel engine 10.
, a feed pump 42B (FIG. 2 shows a state in which it is expanded at 90') for pressurizing fuel, which is fixed to the pump drive shaft 42A, and a fuel pressure adjustment valve 42C for adjusting the fuel supply pressure. For example, 1! is used to detect the crank angle reference position, such as top dead center (TDC), from the rotational displacement of the pump drive pulley 42D fixed to the pump drive shaft 42A. a reference position sensor 44 consisting of a magnetic pickup;
NE balsa 42 also fixed to pump drive shaft 42△
For example, the roller ring 42H is fixed to the roller ring 42H for detecting the rotational state of the engine from the rotational displacement of E. i... NE sensor 46 consisting of a pickup and face cam 42
A roller ring 42H for reciprocating the F and plunger 42G and changing the timing thereof, and a timer piston 42J for changing the rotational position of the roller ring 42H (FIG. 2 shows a 90° expanded state). ) and
A TCV 48 for controlling the injection timing by controlling the position of the timer piston 42J, and an electromagnetic spill for controlling the fuel injection amount by changing the timing for releasing fuel from the plunger 42G via the spill boat 42K. A valve 50, a fuel cut valve 52 for cutting off fuel, and a delivery valve 42L for preventing backflow of fuel and back molding are provided. A glow current is supplied to the glow plug 36 via a glow relay 37. The above-mentioned intake air pressure sensor 12, accelerator position sensor 20, intake pressure sensor 32, ignition timing sensor 38, water temperature sensor 40
．． The W heavy position sensor 44, the NE sensor 46, the glow current sensor 54 that detects the glow current flowing through the glow plug 36, the key switch, the air conditioner switch, the neutral safety switch output, the vehicle speed signal, etc. are controlled by an electronic control unit (hereinafter referred to as ECU). ) 56 and processed by the output of the ECU 36, the VSV 28.
30, glow relay 37, TCV48, electromagnetic spill valve 5
0, the fuel cut valve 52 and the like are controlled. The ECU 36 is configured to operate various FI! Central processing unit (hereinafter referred to as CP) for processing
(referred to as U) 56A, and a read-only memory (hereinafter referred to as ROM) for storing control programs and various data.
56B, a random access memory (hereinafter referred to as RAM) 56C for temporarily storing calculation data etc. in the CPLI 56A, a clock 56D that generates a clock signal, and an input via a buffer 56E. Output of the water temperature sensor 40, buffer 5
The output of the intake temperature sensor 12 is inputted via 6F, and the intake pressure sensor 32 is inputted via a buffer 56G.
A multiplexer (hereinafter referred to as MPX) 56 for sequentially taking in the output of the accelerator position sensor 20, etc. inputted via a buffer 56H, and a multiplexer (hereinafter referred to as MPX) 56 for converting the analog signal output to the MPX 56 into a digital signal. An analog-digital converter (hereinafter referred to as an A/D converter) 56L and the output of the A/D converter 56L are sent to a CPU 56A.
An input/output boat 56M and a buffer 56 for importing
A starter signal inputted through N, an air conditioner signal inputted through a buffer 56P, a torque converter signal inputted through a buffer 56Q, an output of the ignition timing sensor 38 inputted through a waveform shaping circuit 56R, etc. CPU5
6A, the waveform shaping circuit 56R to waveform-shape the ignition timing sensor 38 output and directly input it to the input interrupt terminal ICAP2 of the CPU 56A, and the reference position sensor 44 output. After shaping the waveform, the same input interrupt terminal ICAP of the CPU 56A is used.
2, a waveform shaping circuit 56T for directly capturing the
a waveform shaping circuit 56U for shaping the waveform of the sensor 46 output and directly importing it into the CPU 56A; and the CPU 56A.
a drive circuit 56V for driving the electromagnetic spill valve 5o@ in accordance with the calculation result of the CPLJ 56A; and a drive circuit 56 for driving the TCV 48 in accordance with the calculation result of the CPLJ 56A.
W, a drive circuit 56X for driving the fuel cut valve 52 according to the calculation results of the CPU 56A, and a common bus 56Y for connecting each component to transfer data and instructions. ing. Here, the ignition signal output from the waveform shaping circuit 56R is
In addition to the input interrupt terminal rcAP2 of the CPU56A,
The reason why it is also input to the input/output port 568 is to distinguish it from the reference position signal output from the waveform shaping circuit 56T, which is input to the same input interrupt terminal ICAP2. The effects of the embodiment will be explained below. In this embodiment, the drive frequency of the TCV 48 is determined according to the flowchart shown in FIG. That is, first, in step 110, the control duty ratio of the TCV 48 is calculated using a known method depending on the engine operating state. Next, the process proceeds to step 112, and the time for which the TCV 48 should be turned on is calculated according to the calculation result of step 110. Next, the process proceeds to step 114, in which it is determined based on the output of the accelerator position sensor 20, for example, whether or not the accelerator pedal 17 is in an idle state in which it is fully opened. If the determination result is negative, the process proceeds to step 116, where it is determined, for example, from the torque converter signal whether the neutral range (hereinafter referred to as N range) is universally selected. If the determination result is positive, the process proceeds to step 118, and from the output of the accelerator position sensor 20, the accelerator interval It
It is determined whether or not A ccp is, for example, a set value within a range of 4 to 10%, for example, 7% or less. If the determination result in step 114 is negative, and the determination result in step 116 or 118 is negative,
That is, when it is determined that the vehicle is not in the idle state and is not in the N range, or that the accelerator opening degree ΔCCp exceeds 7%, the process proceeds to step 120, where the driving frequency of the TCV 48 is set to a normal value, for example, 20 Hz. Exit this routine. On the other hand, when the judgment result in step 114 is positive, or both the judgment results in steps 116 and 118 are positive, that is, the idle state is in the N range, and the accelerator opening degree A CC11 is When it is determined that it is 7% or less, the process proceeds to step 122, and the on-time of the TCV 48 calculated in step 112 is halved. Next, the process proceeds to step 124, where the driving frequency of the TCV 48 is determined. This routine ends with a value of 40 Hz, which is twice the normal value of 20 Hz. In this example, the accelerator opening degree A CC in the no-load state
FIG. 5 shows an example of the relationship between the engine speed and the TCV drive frequency during no-load racing when p is changed from 0% to 40%. In this way, in idle state and N range, and between accelerators, r! T C only when lA ccp is less than a predetermined value
By making the drive frequency of V48 twice the normal one,
It is possible to suppress irregularities in the injection amount in the IIA region where adverse effects are likely to occur, and to effectively suppress idling photography. In addition, in the normal operating state other than the idle state and the state in which the accelerator opening Δccp is equal to or less than a predetermined value in the N range, the TCV48
By keeping the @dynamic wavenumber of T CV
It is possible to limit the number of times the TCV48 operates to about 20 to 30% more than in the past, prevent the lifespan of the TCV4B from being significantly shortened, and bring it to a level where there is no problem in terms of reliability. can. In this embodiment, the operating state near the idle is in the neutral range and the accelerator-to-accelerator rlJ A CCp is below the predetermined value of 7%, so the influence of irregular injection is reduced as shown in Fig. 5 above. During no-load racing, which is unlikely to occur, the drive frequency can be changed faster than changes in engine speed, which is advantageous in terms of reliability. Note that the operating state near idle is not limited to this. In addition, in this embodiment, a higher driving frequency than usual is used.
Since the normal driving frequency is 2@, the control logic is very simple. Note that the drive frequency higher than normal can be set to an arbitrary value in consideration of the degree of irregular injection, the reliability of the TCV 48, and the like. Note that when switching the drive frequency using the accelerator opening degree ACC11, for example, as in the second embodiment shown in FIG.
When switching from 1z to 40Hz, accelerator opening ACC
I) It is also possible to switch at -6%. When hysteresis is provided in the accelerator opening as in the second embodiment, hunting can be prevented when switching the drive frequency. [Effects of the Invention] As explained above, according to the present invention, it is possible to effectively suppress idle vibration caused by unsteady irregular injection,
Moreover, by minimizing the increase in the number of TCV operations,
This has an excellent effect in that reliability can be maintained at a level without any problems.

[Brief Description of the Drawings] Fig. 1 is a flow chart showing the gist of the fuel injection control method for a diesel engine according to the present invention, and Fig. 2 is a flowchart showing an example of an electronically controlled diesel engine for automobiles in which the present invention is adopted. A sectional view including a partial block diagram showing the overall configuration, Part 3
The figure is a block diagram showing the configuration of the electronic control unit used in the embodiment, FIG. 4 is a flowchart showing a routine for determining the drive frequency of the timer control valve, and FIG. FIG. 6 is a diagram showing an example of the relationship between the accelerator opening, the engine rotation speed, and the timer control valve drive frequency during no-load racing in the above embodiment, and FIG. FIG. 7 is a diagram showing an example of the relationship between control valve drive frequency; FIG. 7 is a diagram showing an example of the relationship between plunger lift and engine rotation pulse in a solenoid valve spill type fuel injection pump; FIG. A cross-sectional view showing the installation of the engine rotation balsa to the fuel injection pump, FIG. 9 is a cross-sectional view taken along the rX-rX line in FIG. 8.
A cross-sectional view, FIG. 10, is a diagram showing a state in which the actual spill timing deviates from the original spill timing due to the rotation of the roller ring in the conventional example, and FIG. 11 is a diagram showing the plunger lift in the conventional example. , is a diagram showing an example of the relationship between the amount of rotation of the roller ring and the on/off state of the timer control valve. 10... Diesel engine, 20... Accelerator position sensor, A ccp... Accelerator opening, 42... Fuel injection pump, 42E... Engine rotation (NE) balsa, 42G...
・Plunger, 42H...Roller ring, 42J...Timer piston, 46...Engine rotation (NE) sensor, 48...Timer control valve (TCV), 56...Electronic 1IiIJ sin unit (ECU) .

Claims (4)

[Claims] (1) The electromagnetic spill valve operates in synchronization with the plunger lift of the fuel injection pump, and based on the target spill timing determined by converting the target spill angle into time from the signal input at every predetermined pump angle and the engine rotation speed. In a diesel engine fuel injection control method, the fuel injection amount is controlled by on/off control of a timer control valve, and the fuel injection timing is controlled by on/off duty control of a timer control valve. A procedure for detecting that the timer control valve is driven at a normal driving frequency in idle or near-idle normal operating conditions; A method for controlling fuel injection for a diesel engine, comprising: a procedure for driving a timer control valve; and a method for controlling fuel injection for a diesel engine. (2) The fuel injection control method for a diesel engine according to claim 1, wherein the operating state near the idle is in the neutral range and the accelerator opening is below a predetermined value. (3) The fuel injection control method for a diesel engine according to claim 2, wherein hysteresis is provided in the accelerator opening degree when switching the drive frequency. (4) The fuel injection control method for a diesel engine according to claim 1, wherein the drive frequency higher than normal is an integral multiple of the normal drive frequency.