JPH0318646A - Fuel injection control device for diesel engine - Google Patents

Abstract

PURPOSE:To prevent the injection quantity from becoming excessively large or small by performing spark advance/delay correction to the force-feed terminating time according to the actual can oil feed rate following the relative response delay between a fuel return passage switching mechanism and a cam phase changing mechanism. CONSTITUTION:An enumerting means 29 enumerates the target force-feed terminating time from the engine speed and accelerator opening detected at sensors 23, 24 through a target force-feed starting time setting means 26 and a target injection quantity setting means 25. In order to obtain the target injection quantity according to the actual oil feed rate by a face cam detected at a sensor 30, the target force-feed terminating time is subjected to spark advance/delay correction at a means 31, and the driving of a return passage switching mechanism 21 is controlled through a driving pulse output means 32. The target oil feed rate is also set at a setting means 27 on the basis of the engine speed, and the driving of a cam phase control mechanism 22 is controlled through a driving signal output means 28. The injection quantity is thus prevented from becoming excessively large or small even at the transient time, and the increase of noise and the generation of smoke at the time of sudden acceleration can suppressed.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) This invention relates to improvements in fuel injection control devices for diesel engines. (Japanese technology) Some fuel injection devices for diesel engines are equipped with a unit injector and control the injection rate by controlling the timing of stopping energization to the electromagnetic L//id mechanism of this injector. (Vf Leap 59-16
(See Publication No. 2357).

To explain this, in Figure 14, if the electromagnetic solenoid mechanism is closed early when the cam speed is low as shown by the solid line, the injection pressure will not increase due to the low cam speed and the injection rate will decrease. This increases the injection period. On the other hand, if the electromagnetic solenoid/idome structure is closed late, as shown by the broken line, when the cam speed is high, the high cam speed region will be used, which will increase the injection pressure and the injection rate. The injection period can be shortened. In this example, the injection pressure under full load is high at low speeds, and low at high speeds, as shown in Figure el415. However, if the electromagnetic solenoid mechanism is only controlled with respect to the cam speed, the optimal injection timing will change depending on the cam speed (if the 74 magnetic solenoid mechanism is closed late, the injection timing will also be delayed). ). Therefore, a separate timer mechanism is installed to adjust the injection timing according to the leap period of the electromagnetic solenoid/idle mechanism. For example, in the example shown in FIG. 14, the delayed injection timing as shown by the broken line is advanced by the timer mechanism to the point W shown by the point #I line.

(Problem to be Solved by the Invention) In such a device, first, the timing for starting pressure feeding of the cam is determined so that a target oil feeding rate (injection rate) is achieved;
Next, by correcting the phase of this cam, the cam's pumping start timing is configured to not deviate from the predetermined target pumping dark start timing, and the electromagnetic solenoid In contrast, the cam phase, or injection timing, is adjusted by a timer mechanism.
However, the responsiveness of both mechanisms is not necessarily the same. Therefore, if the timer mechanism has a slower response than the electromagnetic solenoid mechanism, this response delay during transients such as acceleration or deceleration may cause the actual pumping of the cam to be delayed. The start timing deviates from the target value, and during sudden acceleration, combustion noise becomes louder and smoke increases. This invention is a! ! It was developed in 1999, and the start timing of fuel pumping can be controlled by a solenoid valve as an open rFI Iso-elli installed in the fuel return passage, and the oil feeding rate can be controlled by
Variable cam phase consisting of timer piston and control well 8! Each structure is controlled independently, and the cam phase is variable (1fi?). Target injection 1t caused by relative response delay of 4.
It is an object of the present invention to provide a device that can eliminate the deviation from the amount by correcting the advance/delay of the pumping end timing.

(Means for Solving the Problems) As shown in FIG. 1, the second invention provides a 7-eed pump and a plunger pump that rotate in synchronization with one rotation of the Ennon, and is formed on the discharge side of the 7-eed pump. P/9. A fuel return passage that communicates between a low-pressure pump chamber and a high-pressure chamber of the Planoya pump receives a drive pulse to open and close this passage during the pressurization stroke of the plunger pump.
The fuel injection pump is equipped with a mechanism 21 and a locking mechanism 22 that can change the phase of a face cam fixed to the plunger of the plunger pump, and a sensor (for example, an engine rotation Number Ne
a sensor 23 for detecting the engine load, a sensor 24 for detecting the accelerator jump as the engine load, means 25 and 26 for respectively setting the target injection amount and the target pumping start time XAT+ according to the detected values, and the fuel return A target oil feed rate Qo by the face cam during the pumping period from closing to opening of the opening/closing mechanism 21 installed in the passage is set according to the detected value of the operating condition (for example, the engine non-rotation speed Ne). means 27; and means 28 for generating a drive signal according to the target oil feed rate Qo and outputting it to the cam phase variable mechanism 22;
a means 29 for calculating a target pressure-feeding end time T2 from the target injection 1 ton amount and the target pressure-feeding start time T1; a sensor 30 for detecting the critical oil feed rate by the face cam; , a means 31 for advancing or retarding the target pressure-feeding end time T2 so as to obtain the target injection amount, and the corrected target pressure-feeding end time and target pressure-feeding start time T.
, and are interposed in the rod return passage to generate a driving pulse from ll? ! Closed 8! A means 32 for outputting to the structure 21 is provided.

(Function) Even in this invention, although the oil feeding rate by the face cam is changed according to the operating conditions, the timing to start pumping fuel is determined in accordance with the closing timing of the opening/closing mechanism 21 installed in the fuel return passage. Therefore, it is not affected by changes in the oil delivery rate, and the timing at which pressure pumping starts (i.e., injection timing) does not shift even during transient situations such as sudden acceleration. Furthermore, due to the relative response delay of the variable cam phase mechanism 22 during sudden acceleration, the actual oil supply rate may become higher than the target value, and more fuel may be supplied by the increased rate. On the other hand, according to the present invention, the amount that deviates to the higher side is detected by detecting the actual oil feeding rate using the sensor 30, and in this case, the end timing of the pumping is brought forward, so that the fuel It is ensured that there is no excess.

(Example) Figure 2 is a sectional view of a distribution type fuel injection pump according to an example. 4 is a drive sleeve connected to the output shaft of the engine (not shown);
Reference numeral 2 denotes a pane-type 7-eed pump driven by this driving glaze 4. Fuel sucked by the 7-eed pump 2 from a fuel inlet (not shown) is supplied to a pump chamber 5 in the housing 1, and a suction passage opens into the pump chamber 5. 6 to the high pressure chamber 12 of the Plannoya pump 3. A claw 9a of a face cam 9 fixed to the left end of the bran head 7 is connected to one M1 (the right end in the figure) of the driving pongee 4 so as to be slidable in the axial direction. The plunger 7 is located on the same line as the driving pongee 4, and the plunger 7 is configured to be displaceable in the axial direction.

On the outer periphery of the connection portion between the drive sleeve 4 and the face cam 9, a roller hog 10 carrying a plurality of rollers 11 is attached to the drive sleeve 4.
The face cam 9 has a cam surface 9b which is arranged concentrically with the roller 11, and the face cam 9 is formed with a cam surface 9b for controlling a number of non-uniform speed cams corresponding to the number of cylinders. ing. 15 is a fuel cut pulp that closes when the engine is stopped. The planoya 7 has the same number of suction grooves 8 as the cylinders of the Ennon at its tip, and the cam surface 9b rotates together with the driving pongee 4 while the roller 1 is disposed on the roller hole 1o.
When the cam 1J7 moves back and forth by a predetermined amount, the fuel sucked into the high pressure chamber 12 through the suction groove 8 passes through the delivery valve of each 11 distribution boat (not shown) communicating with the high pressure chamber 12 to the injection nozzle. It is pumped. Reference numeral 13 denotes a fuel return passage that communicates the high pressure chamber 12 and the low pressure pump chamber 5, and this fuel return passage 13 has a high-speed response valve that is driven according to the operating conditions of the ENON by a signal (drive pulse) from the drive circuit. Type solenoid valve (open 1!Hj!vt) 1 4
is interposed. This solenoid valve 14 is provided for fuel control, and during the pressurizing stroke of the plunger 7, the solenoid valve 14
When the solenoid valve 14 is closed, the pumping of fuel starts, and when the solenoid valve 14 is opened, the pumping ends. In other words, the timing at which the solenoid valve 14 is closed controls the timing to start pumping the fuel, and the timing at which the solenoid valve 14 opens controls the timing at which the pumping ends. Note that the fuel injection amount is determined depending on the period from the time when the pressure feeding starts to the time when the pressure feeding ends. This injection pump further includes a mechanism capable of changing the phase of the 7-is cam 9 fixed to the plunger 7, mainly consisting of a timer piston 42 and a control valve 51. Specifically, in FIG. 2, the roller hog 10 is arranged concentrically with the driving pongee 4 so as to be rotatable within a limited fixed angle range, and the roller hog 10 and the timer piston 42 are connected by a connecting lever 41. It will be done. Figure 3 is a sectional view taken along the line X-X in Figure 12, showing the timer piston 4.
Hyperbaric chamber 4 shaped like 2 Ichiyasu full (top full in the figure)
3 is communicated with the pump chamber 5 through an oil passage 44 bored in the timer piston 42 and a connecting hole 45 between the connecting lever 41 and the piston 42, and this high pressure chamber 43 has a high pressure chamber 43 with a pressure corresponding to the engine rotation speed. Fuel pressure is supplied. On the other hand, a low pressure chamber 46 formed on the other end side of the timer piston 42
is communicated with the suction side of the 7-ide pump 2 via an oil passage (not shown), and a timer spring 47 that urges the timer piston 42 toward the high pressure chamber side 43 is compressed in the low pressure chamber 46 .

A fuel oil passage 48 communicating between the high pressure chamber 43 and the low pressure chamber 46 is provided in the pump housing 1, and a valve 51 capable of controlling the duty ratio is provided in this fuel oil passage 48. In this pressure control valve 51, when the solenoid/id 52 is energized, the spool 53 resists the elastic force of the return spring 54, moves to the right in the figure, and opens the valve. When the energization is stopped, the subur 53 moves to the left by the elastic force of the return spring 54, and the valve closes. Here, the pressure difference between the fuel pressure in the high pressure chamber 43 and the sum of the fuel pressure in the low pressure chamber 4G and the elastic force of the return spring 47 is determined by the duty ratio given by the control valve 51 (during the valve opening period per certain period of time). g is adjusted according to the ratio), and the vertical displacement of the timer piston 42 changes. When the timer piston 42 is displaced in this manner, the roller hog 10 is rotated in the circumferential direction via the connecting lever 41, and the contact position between the roller 11 and the cam surface 9b of the cam disc 9 is moved. This movement advances or retards the phase of the reciprocating motion of the plano gear 7 relative to the rotation of the drive shaft 4, that is, the starting point of the cam lift. Here, the data ratio signal (
The phase of the face cam 9 is freely controlled by the drive signal). The structures of the injection pump shown in FIG. 12 and the cam phase variable fi structure shown in FIG. 3 are well known.

Figure 4 is a block diagram of the @Il system. 62 is a sensor that detects the accelerator jump as the engine load, and 63 is a sensor that detects the cooling water temperature.These sensors 62t63
constitutes a sensor that detects operating conditions together with a rotation speed sensor, which will be described later. Reference numeral 64 denotes a sensor that outputs an output according to the displacement of the timer piston 42, and is installed, for example, in the high pressure chamber 43 in FIG.
is detected. This sensor 64 functions as the oil feed rate sensor 30 shown in Fig. 1. The signals from Senna 62 to 64 are
It is input to the control unit 6G along with the re-7T lens pulse and scale pulse from the injection pump. ″
:! The trawl unit 66 is constituted by the micro combinator and includes the solenoid valve 14 for controlling the start timing and end timing of fuel pumping according to the operation shown in FIG.
At the same time, it outputs a drive signal according to the duty ratio to the control valve 51 for changing the phase of the 7-is cam 9. In comparison with FIG. 1, the control unit 66 includes the functions of means 25 to 29, 31, and 32. FIG. 7 shows a routine for driving and controlling the solenoid valve 14 and the control valve 51.
First, let me explain using Figure 6.

In FIG. 6, the solid line indicates the cam speed characteristic at a steady state of 1 l. Once the target pressure feed start time T1 and the target injection fiQ are determined, the I target pressure feed end time T2 can be determined from these values TQ. This is the diagonal #1 surrounded by the downward-sloping straight line of the cam speed shown and the vertical line of TI+72.
The area of the portion corresponds to the injection amount, and since the linear position of the downward slope of the cam speed to the right is known in advance, once T1 is determined, T2 is determined. In addition, each period T+t
The value of T2 (also for T 3t and T 3', which will be described later) is the crank angle from compression top dead center TDC. Now, during a transient period, for example, during sudden acceleration, the cam speed diagram may deviate by a predetermined amount from the solid line to the broken line in FIG. 6 due to the relative response delay of the timer piston 42 to the solenoid valve 14. Here, if it is assumed that there is no relative response delay, the deviation of the cam speed diagram is not taken into account, and therefore, in this case as well, the pumping ends at the same time T2. However, in this case, injection is performed corresponding to the area rs* between the downward-sloping straight line of the cam speed shown by the broken line and the vertical line of TlIT2, so the injection is performed according to the area difference with the diagonal #1 part. Therefore, more fuel than the target injection amount Q is injected. To avoid this, advance the timing of T2 (advance the end of pumping). Then, how much to advance should be determined according to the deviation in the cam speed diagram.In other words, in the diagram, the target force excess 7F start timing is T3, and the actually detected camry 7F start timing is T3'. For example, these deviations ΔT3 (=T3−
73'). At this moment, the start time of Camry 7 corresponds to the timer piston position, so
It is possible to replace T3 with the target timer piston position and T3' with the actual timer piston position. Note that instead of giving T2 as a function of T1 and ΔT3, T1
and 73' may be given as a function.

Entering FIG. 7, in S1, the operating condition signals of the engine speed Ne, accelerator opening, and cooling water temperature are read. In addition,
As shown in FIG.
Input the following to calculate the mechanical non-rotation speed (N e). In other words, the sensor that generates both pulses corresponds to the rotation speed sensor 23 in the younger brother 1.

In S2, the target pumping start time T1 is determined according to the engine rotational speed Ne using a method such as referring to a map. The contents of TI are shown in Figure 8. The higher the engine speed, the earlier the pumping starts to prevent injection delays. In S3, the target basic injection amount QO is determined according to the engine speed Ne and the accelerator opening. Qo contents PIS9
As shown in the figure. % in the figure means the ratio of the accelerator opening to the fully open position. The above-mentioned cooling water temperature is a signal for increasing and correcting this Qo, and the injection amount corrected to increase based on the cooling water temperature is determined as the target injection IQ. In S4, depending on the accelerator pedal stroke, as shown in the face cam 0 diagram, the larger the accelerator pedal opening, the larger the fuel feed rate is to prevent fuel supply delays. In addition, T + * Q O+ shown in FIGS. 8 to 10
Q o is obtained in advance through experiments or the like in accordance with various engine conditions such as the engine speed and the degree of acceleration, and the value is stored in a storage element such as a ROM in the control unit 66. In S5, the target oil feed rate Qo is set to the target timer piston position T3.
Convert to . This is because the oil feed rate corresponds to the cam speed (the higher the cam speed, the higher the oil feed rate), and the cam speed changes depending on the start time of Camry 7F (timer piston position ffi), so after all, the oil feed rate corresponds to the cam speed. This is because the oil rate and timer piston position correspond to IN1. In other words, S4 and S5 are the parts that perform the function of the target oil feed rate setting means 27 shown in FIG. In S6, the actual timer piston position T3' detected by the sensor 64 is read. Needless to say, this 73' corresponds to the actual oil delivery rate. In S7, the target pressure-feeding end time T2 is calculated from the target pressure-feeding start time T1 and the actual timer piston position T3' so as not to deviate from the target basic injection fftQo (or target injection IQ) determined in step 83. For example, if T3' is later than the target value T3, more fuel than Qo will be injected, so by advancing the target pumping end time, the injection amount is returned to the target value, and this i! ! If T3' is earlier than the target value T3, the injection amount is returned to the target value by retarding the target pumping end timing. S7 functions as both the target pumping end time calculation means 29 and the advance/retardation correction means 31 in the fjS1 diagram.

In S8, the target pressure-feeding start time T1 and the target pressure-feeding end time T2
And the target timer piston position T3 is transferred to the output interface 7ace (not shown). The output interface 7 ace generates a pulse that rises at time T1 and falls at time T2 and outputs it to the solenoid valve 14. The solenoid valve 14 closes in an interleaved manner in response to this driving pulse, and pumps fuel during the interleave period. Cru. Furthermore, the inter 7 ace generates a drive signal with a duty ratio corresponding to T3 and outputs it to the control valve 51. In other words, the inter 7 ace is the drive pulse output means 32 in FIG.
and 8 as the drive signal output means 28! function.

Here, to explain the operation of this example, in this example as well,
Although the oil delivery rate by the face cam is changed according to the operating conditions, the oil delivery start time is determined in accordance with the closing timing of the solenoid valve 14 installed in the fuel return passage 13, so the oil delivery rate is changed depending on the operating conditions. Since the solenoid valve 14 itself is not affected by changes in the rate, and the solenoid valve 14 itself usually has good responsiveness, the pumping start timing, that is, the injection timing, will not shift even during transient situations such as sudden acceleration. do not have.

On the other hand, due to the relative response delay of the timer piston 42 during sudden acceleration, the timer piston position may become later than the target value, and more fuel may be supplied by the amount of the deviation. On the other hand, according to this example, such a deviation is detected by detecting the actual timer piston position using the sensor 64, and in this case, by advancing the end timing of pressure feeding, it is possible to detect excess fuel. This avoids an increase in noise and smoke. FIG. 11 shows another embodiment in which the pumping start timing is brought forward in order to suppress the occurrence of smoke when the engine is throttled from idle to 7 rev.

This is because, as shown in Fig. 10, the cam speed diagram is moved to the position of the broken line in Fig. 6 so that the oil delivery rate is high at the 7-speed throttle (the high cam speed region is used). In other words, it is necessary to retard the timer piston position, but if the timer piston 42 can only move to the solid line position due to the response delay when the timer piston 42 is throttled from idle, the oil delivery rate will decrease. This is because the space utilization rate deteriorates and smoke may occur. Therefore, at 7 times from idle, the pumping start timing is advanced according to the degree of response delay of the timer piston 42. Specifically, in Sll~15, 7? The configuration is such that the lag A is set when it is determined that the time is idle (A = 1), and the 7 lag B is set when it is determined that the time is idling and the time is 7 throttle (B = 1). To avoid this, in S19, the value of B is used to determine whether or not the throttle is 7 degrees from idle. and,
If this is determined, proceed to 820.21, where the timer piston position response delay 11T3'-T31 is a
(predetermined tolerance value of 173'-731) or more, the target pumping start timing T1 is advanced by IT3'-T31/α. However, the target basic injection IQo is not changed.

Finally, a closed-loop control system can be constructed for the two embodiments described above. For example, in order to actually detect when to start pumping fuel and when to end pumping, it is necessary to
) and (B) are installed on the solenoid valve 14. Here, the opening/closing timing sensor is Haunong 14.
Insulating coating 1 on the outer periphery of needle valve 14B that slides inside A
4C, the nail 14B and the housing 14A (both are conductors) are insulated with the needle 14B open as shown in Figure 12 (A), and the needle valve 14B is opened as shown in Figure 12 (A). As shown in B), when the 'Xi position occurs, both of them shift. When a detection resistor (R) is connected in parallel to both of them and a current is passed through it, the sensor output shown in the f513 diagram is generated at both ends of R. is obtained. Therefore, based on the signals from the second sensor, the control unit 6G is configured so that the actual pumping start time coincides with the @standard pressure feeding interval start time T1 and the actual pumping end time coincides with the target pumping end time T2. When 7 feedback control is performed, control accuracy is improved compared to oven loop control. (Effects of the Invention) According to the present invention, the opening W1 mechanism and the cam phase are variable, which are installed in the fuel return passage so that the fuel pressure-feeding start timing and the oil-feeding rate each reach target values determined according to the operating conditions. While controlling the cam mechanism independently, it also prevents the supply of fuel that deviates from the predetermined target injection amount due to the relative response delay of both mechanisms. As a result, even during transient periods, the pumping start timing (injection timing) may be excessively advanced or retarded, or the injection amount may be excessively large or small. This suppresses the increase in noise and the occurrence of smoke, especially during sudden acceleration.

[Brief explanation of drawings]

Fig. 1 is a diagram corresponding to the claims of the present invention, Fig. 2 is a cross-sectional view of a fuel injection pump according to an embodiment of the present invention, Fig. 3 is a cross-sectional view taken along the line A block diagram of the example control system, Fig. 5 is a waveform diagram showing reference pulses and scale pulses, Fig. 6 is a cam speed diagram for explaining the control concept of the above embodiment, and Fig. 7 is this embodiment. Flowcharts for explaining the control operation of the pine tree used in this control operation, Figs. FIG. Fig. 11 is a flowchart of another embodiment, Fig. 12 (A), younger brother 1
Figure 2 (B) is a structural diagram of the opening/closing timing sensor in the open and closed states of the solenoid 14, respectively, and Figure 13 is a diagram of the output characteristics of the sensor. Fig. 14 is a waveform diagram for explaining the effect of the example of the 1st wave.
Figure 5 shows the injection pressure characteristics at full load for the conventional model. DESCRIPTION OF SYMBOLS 1... Pump housing, 3... Plannoya pump, 5... Pump chamber, 7... Plannoya, 9... Face cam, 12... High pressure chamber, 13... Fuel return passage, 14... ... Solenoid valve (opening/closing mechanism), 21... Fuel return passage opening/closing mechanism, 22... Cam phase variable 8! structure, 23
・・・Rotation loss seven children, 24...Accelerator opening sensor,
25...Target injection tvk fixing means, 26...Target pumping start timing setting means, 27...Target oil feeding rate setting means, 2
8... Drive signal output means, 29... Target pumping end time calculation means, 30... Oil feed rate sensor, 31... Advance/retard angle correction means, 32... Drive pulse output means, 41.・
・Connection lever 42...timer piston, 48...
Fuel passage, 51... Pressure control valve, 62... Accelerator opening sensor, 63... Water temperature sensor, 64... Timer piston position sensor, 66... Fuel control unit,

Claims (1)

[Claims] A feed pump and a plunger pump are provided that rotate in synchronization with engine rotation, and a fuel return passage that communicates a low-pressure pump chamber formed on the discharge side of the feed pump with a high-pressure chamber of the plunger pump receives driving pulses. The fuel injection pump is provided with a mechanism that opens and closes this passage during a pressurizing stroke of the plunger pump, and a mechanism that can change the phase of a face cam fixed to the plunger of the plunger pump. , a sensor for detecting engine operating conditions, a means for setting a target basic injection amount and a target pumping start timing according to the detected values, and a means for opening and closing an opening/closing mechanism installed in the fuel return passage. Means for setting a target oil feed rate by the face cam during the pumping period according to the detected value of the operating conditions, and a drive signal corresponding to the target oil feed rate, which is output to the cam phase variable mechanism. means for calculating the target pumping end time from the target basic injection amount and the target pumping start timing; a sensor for detecting the actual oil feeding rate by the face cam; Means for advancing or retarding the target pumping end time so as to obtain the injection amount, and generating a drive pulse from the corrected target pumping end timing and the target pumping start time, and interposed in the fuel return passage. 1. A fuel injection control device for a diesel engine, comprising means for outputting to an opening/closing mechanism.