JPH0229859B2 - DEIIZERUENJINNONENRYOFUNSHASEIGYOHOHO - Google Patents

Description

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

The present invention relates to a fuel injection control method for a diesel engine, and particularly to a method for controlling fuel injection in synchronization with a plunger lift of a fuel injection pump, which is suitable for use in an electronically controlled automobile diesel engine using a solenoid valve spill type fuel injection pump. , and based on the spill timing determined by converting the angle into time from the signal input at each predetermined pump angle and the engine rotation speed, the fuel injection amount is controlled by on/off control with the electromagnetic spill valve, and the timer is also activated. 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 control valve.

[Conventional technology]

In recent years, with the development of electronic control technology, especially 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 for electronically controlling a fuel injection pump, and one of them is a so-called electromagnetic spill type fuel injection pump in which fuel spill in the fuel injection pump is controlled by an electromagnetic valve. In this electromagnetic spill type fuel injection pump, when the fuel injection amount reaches the target value, the electromagnetic spill valve opens the spill port and controls the end of fuel pumping, thereby controlling the fuel injection amount. That's what I do. In such an electromagnetic spill type fuel injection pump, normally, as shown in FIG. ) and the average engine speed, the target spill angle is converted into time to determine the target spill timing, and the electromagnetic spill valve is controlled on/off based on the target spill timing. 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, usually the NE pulse is the eighth
As shown in FIG. 9 and FIG. 9, an engine rotating pulsar (hereinafter referred to as NE pulsar) 42E, which is press-fitted into a pump drive shaft 42A and has a gear and its teeth missing on its outer periphery, and a roller 42I are rotatably mounted. Engine rotation speed sensor (hereinafter referred to as NE sensor) 4 provided on the supporting roller ring 42H
6, the plunger 4
When 2G lifts, due to the reaction force from the face cam 42F transmitted via the roller 42I,
The roller ring 42H is slightly rotated in the driving direction, and the time conversion amount and the plunger lift are out of synchronization, and as shown in FIG. 10, the spill occurs at a time _t2 slightly earlier than the time t1 when it should _originally spill. This results in the phenomenon that the person is left behind. 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 controls the high fuel pressure applied to the piston end surface (the left end surface in the figure) by a timer control valve (hereinafter referred to as TCV). ) 48 is changed by on/off duty control, and the roller ring 42H is rotated to obtain the target injection timing. However, if the frequency that drives this TCV48 is small,
Each time the on time, that is, the voltage release time becomes longer, and as shown in Fig. 11, when the on time coincides with the plunger lift time, that is, when the face cam reaction force and the on time coincide, the spill timing as described above occurs. The problem is that as the deviation becomes larger and the injection amount fluctuates unsteadily and becomes irregular, vibration may worsen, especially in areas where the influence of the injection amount is easily reflected in the rotation speed, such as during idling. It had a point. In order to solve these problems, TCV48
It is conceivable to uniformly increase the driving frequency of the TCV48, but in this case, the number of operations of the TCV48 increases dramatically, shortening the lifespan of the TCV48, which is unfavorable in terms of reliability. Ta.

[Purpose of the invention]

The present invention has been made to solve the above-mentioned conventional problems, and is a diesel engine that can suppress irregularities in injection amount to a level that does not worsen idle vibration without significantly shortening the life of the timer control valve. The purpose of the present invention is to provide a fuel injection control method.

[Means to solve the problem]

The present invention synchronizes with the plunger lift of a fuel injection pump and generates an electromagnetic spill based on a target spill timing determined by converting a target spill angle into time from a signal input at every predetermined pump angle and the engine rotation speed. Figure 1 shows the outline of a diesel engine fuel injection control method in which the fuel injection amount is controlled by on/off control of a valve, and the fuel injection timing is controlled by on/off duty control of a TCV. As shown, the procedure for detecting idle and near-idle operating states, and the normal operating state other than idle or near-idling, are as follows:
By including a procedure for driving the TCV, and a procedure for driving the TCV at a higher drive frequency than normal in idle and near-idle operating conditions,
The above objective has been achieved. Further, in an embodiment of the present invention, the operating state near the idle is in the neutral range and the accelerator opening is below a predetermined value. 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.

[Effect]

In the present invention, electromagnetic control is performed based on a target spill timing determined by converting a target spill angle into time from a signal input at every predetermined pump angle and the engine rotation speed in synchronization with the plunger lift of the fuel injection pump. When controlling the fuel injection amount by on/off control of the spill valve and the fuel injection timing by on/off duty control of the TCV, in idle and near-idle operating conditions, the drive frequency is higher than normal.
It is designed to drive TCV. Therefore, at idle and in the vicinity of idle, where vibrations may worsen, the spill timing shift is not exacerbated, and it is possible to prevent idle vibrations from worsening. In addition, in normal operating conditions other than idle or near idle, the TCV is driven at the normal drive frequency, so the number of TCV operations can be minimized, and the number of operations increases significantly. Its lifespan will not be shortened. Furthermore, when the operating state near the idle is in the 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. , which is advantageous in terms of reliability. Furthermore, when hysteresis is provided in the accelerator opening 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 frequency, the control logic is simple.

【Example】

DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of an electronically controlled diesel engine for automobiles, in which a fuel injection control method according to the present invention is adopted, will be described in detail below 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. Downstream of the intake air temperature sensor 12 is a turbine 14 that is rotated by the thermal energy of the exhaust gas.
A, and a compressor 14B that rotates in conjunction with the turbine 14A.
is provided. The upstream side of the turbine 14A of the turbocharger 14 and the downstream side of the compressor 14B are communicated via a wastegate valve 15 for preventing an excessive rise in intake pressure. Bench lily 1 on the downstream side of the compressor 14B
6 is an accelerator pedal 1 located at the driver's seat to limit the flow rate of intake air during idling, etc.
A main intake throttle valve 18 is provided which is configured to rotate non-linearly in conjunction with the main intake throttle valve 7. Opening degree of the accelerator pedal 17 (referred to as accelerator opening degree) Accp
is detected by the accelerator position sensor 20. A sub-intake throttle valve 2 is installed in parallel with the main intake throttle valve 18.
2, and the opening degree of the sub-intake throttle valve 22 is controlled by a diaphragm device 24. The diaphragm device 24 includes a negative pressure pump 2
The negative pressure generated in step 6 is transferred to the negative pressure switching valve (hereinafter referred to as VSV).
) 28 or 30. An intake pressure sensor 32 is provided downstream of the intake throttle valves 18 and 22 to detect the pressure of intake air. Cylinder head 10 of diesel engine 10
A is equipped with an injection nozzle 34 whose tip faces the engine combustion chamber 10B, a glow plug 36, and an ignition timing sensor 38. 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 is connected to the diesel engine 1.
A pump drive shaft 42A that rotates in conjunction with the rotation of the crankshaft 0, and a feed pump 4 fixed to the pump drive shaft 42A for pressurizing fuel.
2B (Fig. 2 shows the 90° unfolded state), a fuel pressure adjustment valve 42C for adjusting the fuel supply pressure, and a crank angle reference based on the rotational displacement of the pump drive pulley 42D fixed to the pump drive shaft 42A. position,
A reference position sensor 44 consisting of, for example, an electromagnetic pickup for detecting, for example, top dead center (TDC)
and NE, which is also fixed to the pump drive shaft 42A.
An NE sensor 46 consisting of, for example, an electromagnetic pickup fixed to a roller ring 42H, a face cam 42F, and a plunger 42 for detecting the rotational state of the engine from the rotational displacement of the pulser 42E.
A roller ring 42H for reciprocating G and changing its timing, and a timer piston 42J for changing the rotational position of the roller ring 42H (Figure 2 shows the state unfolded at 90 degrees).
and a TCV 48 for controlling the injection timing by controlling the position of the timer piston 42J.
and plunger 4 via spill port 42K.
Electromagnetic spill valve 50 for controlling the fuel injection amount by changing the fuel release timing from 2G
and a fuel cut valve 52 for cutting off fuel.
and a delivery valve 42L for preventing backflow or dripping of fuel. The glow plug 36 includes a glow relay 37.
A glow current is supplied through the The intake temperature sensor 12 and the accelerator position sensor 2
0, intake pressure sensor 32, ignition timing sensor 38, water temperature sensor 40, reference position sensor 44, NE sensor 46, glow current sensor 54 that detects the glow current flowing to the glow plug 36, key switch, air conditioner switch, neutral safety The switch output, vehicle speed signal, etc. are input to an electronic control unit (hereinafter referred to as ECU) 56 and processed.
30, glow relay 37, TCV 48, electromagnetic spill valve 50, fuel cut valve 52, etc. are controlled. The ECU 56, as shown in detail in FIG.
A central processing unit (hereinafter referred to as CPU) 56A for performing various calculation processes, a read-only memory (hereinafter referred to as ROM) 56B for storing control programs and various data, etc.
Random access memory (hereinafter referred to as
(referred to as RAM) 56C, a clock 56D that generates a clock signal, the output of the water temperature sensor 40 inputted via a buffer 56E, and a buffer 56C.
6F, the output of the intake pressure sensor 32, which is input via the buffer 56G, the output of the accelerator position sensor 20, which is input via the buffer 56H, etc. A multiplexer (hereinafter referred to as MPX) 56K and an analog converter for converting the analog signal of the MPX 56K output into a digital signal.
Digital converter (hereinafter referred to as A/D converter)
56L and the A/D converter 56L output to the CPU 5.
6A, a starter signal inputted via a buffer 56N, an air conditioner signal inputted via a buffer 56P,
An input/output port 56S for inputting the torque converter signal input via the buffer 56Q, the output of the ignition timing sensor 38 input via the waveform shaping circuit 56R, etc. to the CPU 56A, and waveform shaping of the output of the ignition timing sensor 38. the waveform shaping circuit 56R for directly inputting the signal to the input interrupt terminal ICAP2 of the CPU 56A; and the reference position sensor 44.
a waveform shaping circuit 56T for shaping the output and directly inputting it to the same input interrupt terminal ICAP2 of the CPU 56A; a waveform shaping circuit 56U for shaping the output of the NE sensor 46 and inputting it directly to the CPU 56A; A drive circuit 56V for driving the electromagnetic spill valve 50 according to the calculation result of the CPU 56A, a drive circuit 56W for driving the TCV 48 according to the calculation result of the CPU 56A, and a drive circuit 56W for driving the TCV 48 according to the calculation result of the CPU 56A. The fuel cut-off valve 52 is driven by a drive circuit 56X, and a common bus 56Y connects each of the component devices to transfer data and commands. Here, the ignition signal outputted from the waveform shaping circuit 56R is inputted not only to the input interrupt terminal ICAP2 of the CPU 56A but also to the input/output port 56S because the waveform shaping circuit 56T is inputted to the same input interrupt terminal ICAP2. This is to distinguish it from the output reference position signal. 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. Then proceed to step 112,
According to the calculation result in step 110, the time for which the TCV 48 should be turned on is calculated. Then step 114
Then, for example, based on the output of the accelerator position sensor 20, it is determined whether or not the accelerator pedal 17 is in an idle state in which it is fully closed. If the determination result is negative, the process proceeds to step 116, where it is determined, for example, from the torque converter signal whether a neutral range (hereinafter referred to as N range) has been selected. If the determination result is positive, the process advances to step 118, and from the output of the accelerator position sensor 20,
It is determined whether the accelerator opening degree Accp is, for example, a set value within a range of 4 to 10%, for example, 7% or less. The determination result in step 114 above is negative, and
If the judgment result in step 116 or 118 is negative, that is, if it is judged that the vehicle is not in the idle state and is not in the N range, or if the accelerator opening degree Accp exceeds 7%, the process proceeds to step 120. ,
Set the driving frequency of TCV48 to the normal value, e.g. 20Hz.
, this routine ends. 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 vehicle is in an idling state or is in the N range and the accelerator opening degree Accp is 7. % or less, the process proceeds to step 122, where the on-time of the TCV 48 calculated in step 112 is halved. Then proceed to step 124,
The driving frequency of the TCV 48 is set to 40Hz, which is twice the normal value of 20Hz, and this routine ends. In this example, accelerator opening in no-load condition
FIG. 5 shows an example of the relationship between the engine speed and TCV drive frequency during no-load racing when Accp changes from 0% to 40%. In this way, only when the accelerator opening Accp is below a predetermined value in the idle state and N range,
By setting the driving frequency of the TCV 48 to twice the normal frequency, irregularities in the injection amount can be suppressed in areas where adverse effects are likely to occur, and idling vibration can be effectively suppressed. In addition, in normal operating states other than the idle state and the N range where the accelerator opening degree Accp is below a predetermined value, by keeping the driving frequency of the TCV 48 as before, the number of operations of the TCV 48 is reduced by 2 to 2 compared to the conventional one. It is possible to keep the increase to about 30%, prevent the life of the TCV48 from being significantly shortened, and bring it to a level where there is no problem in terms of reliability. In this embodiment, the operating state near idle is set to the neutral range and the accelerator opening
Since the operating state is such that Accp is below the predetermined value of 7%, as shown in Figure 5 above, during no-load racing where the effects of irregular injection are unlikely to occur, the drive frequency can be switched faster than the change in engine speed. This is advantageous in terms of reliability. Note that the operating state near idle is not limited to this. Furthermore, in this embodiment, the higher-than-normal drive frequency is twice the normal drive frequency, so 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. In addition, when switching the driving frequency according to the accelerator opening degree Accp, for example, as in the second embodiment shown in FIG. Accelerator opening when switching to 40Hz
It is also possible to switch at Accp=6%. When hysteresis is provided in the accelerator opening as in the second embodiment, hunting can be prevented when switching the drive frequency.

【Effect of the invention】

As explained above, according to the present invention, it is possible to effectively suppress idling vibration caused by unsteady irregular injection, and to minimize the increase in the number of TCV operations, thereby avoiding reliability problems. It has the excellent effect of being able to reduce the level to zero.

[Brief explanation of 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 partial diagram showing the overall configuration of an embodiment of an electronically controlled automobile diesel engine to which the present invention is adopted. FIG. 3 is a cross-sectional view including a block diagram. FIG. 3 is a block diagram showing the configuration of the electronic control unit used in the above embodiment. Similarly, FIG. A flowchart showing the routine, FIG. 5 is a diagram showing an example of the relationship among the accelerator opening degree, engine rotation speed, and timer control valve driving frequency during no-load racing in the above embodiment,
FIG. 6 is a diagram showing an example of the relationship between the accelerator opening and the timer control valve drive frequency in the second embodiment of the present invention, and FIG. 7 is a diagram showing the plunger lift and engine in a solenoid valve spill type fuel injection pump. A diagram showing an example of the relationship between rotational pulses, FIG. 8 is a cross-sectional view showing how the engine rotating pulser is attached to the fuel injection pump, FIG. 9 is a vertical cross-sectional view taken along the - line in FIG. 8, 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.
FIG. 3 is a diagram showing an example of the relationship between the amount of rotation of a roller ring and the on/off state of a timer control valve. 10... Diesel engine, 20... Accelerator position sensor, Accp... Accelerator opening, 42...
...Fuel injection pump, 42E...Engine rotation (NE) pulser, 42G...Plunger, 42H
...Roller ring, 42J...Timer piston,
46...Engine rotation (NE) sensor, 48...
Timer control valve (TCV), 56...Electronic control unit (ECU).

Claims (1)

[Claims] 1. Based on the target spill timing determined by converting the target spill angle into time from the engine rotational speed and the signal input periodically to the plunger lift of the fuel injection pump and at every predetermined pump angle. In a diesel engine fuel injection control method, the fuel injection amount is controlled by on/off control of an electromagnetic spill valve, and the fuel injection timing is controlled by on/off duty control of a timer control valve. A procedure for detecting an operating state near idle; A procedure for driving the timer control valve at a normal driving frequency during idle or normal operating states other than near idle; and A fuel injection control method for a diesel engine, comprising: driving the timer control valve at a higher driving frequency. 2. The diesel engine fuel injection control method 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 diesel engine fuel injection control method according to claim 1, wherein the drive frequency higher than normal is an integral multiple of the normal drive frequency.