JPS58133441A - Fuel injection timing controller of internal-combustion engine - Google Patents

Abstract

PURPOSE:To prevent hunting of injection timing control, by providing a means which changes the integration time constant of a circuit integrating a deviation between a target value and actual value of injection timing in accordance with oil pressure of a hydraulic pressure source. CONSTITUTION:A differential amplifier 108 outputs a deviation DELTAIT between a target value signal ITs and actual value signal ITm of injection timing. A variable time constant integrator 109 outputs an integrated signal S6 of the deviation DELTAIT and changes the integration time constant in accordance with speed of an engine relating to fuel pressure of a pump chamber. In consequence, a unit pulse IS3 of a crank angle sensor 21 is converted into a rotary speed signal through a speed signal generator circuit 118 and then input to the integrator 109. Then a comparator 111 compares a signal from a dither transmitter 110 with the signal S6 to output a pulse signal in proportion to a value of the signal S6. This signal is output as an injection timing control signal OS5, if a driver circuit consisting of a tansistor Q1 or the like is opened and closed, a solenoid valve 54 controlling the injection timing can be duty controlled.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a fuel injection timing control device for an internal combustion engine. The present invention relates to a fuel injection timing control device that controls fuel injection timing.

The fuel injection timing of diesel engines and gasoline engines must be changed depending on the engine rotation speed and load.

In order to precisely control the injection timing, a feedback method as shown in FIG. 3, for example, is used.

(Refer to Japanese Patent Publication No. 5G-5769) In FIG. 3, a deviation detection circuit 101 detects a deviation between a target value signal S2 and an actual value signal 85 of the injection timing, and outputs a deviation signal 84. The control circuit 102 is an integrating circuit, and outputs a control signal S5 that adds integral characteristics to the deviation signal S11. With this control signal S5, the injection timing control mechanism 103
to control the injection timing. The fuel injection valve 104 detects the actual injection timing and outputs an actual value signal S5.

In the feedback type control device as described above, by giving the control signal an integral characteristic, it is possible to maintain control stability and eliminate foot deviation (offset), thereby achieving good control.

However, in such conventional control devices,
6. The injection timing control mechanism is a hydraulic (fuel pressure) type, that is, the injection timing is controlled by controlling the oil pressure. (9) Hydraulic pressure is controlled by adjusting the degree of oil leakage from the pressure oil source to the low pressure side, so the responsiveness is determined by the oil inflow and outflow speeds. Orifices (second
Since the speed of oil flowing through the pipes (corresponding to 56m, 49a, and 53m in the figure) varies depending on the differential pressure before and after the oil pressure, there is another problem in that the responsiveness of injection timing control is affected by the oil pressure of the pressure oil source. Specifically, for example, a diesel engine's distribution fuel injection pump uses the fuel in the pump chamber, whose pressure changes in direct proportion to the engine rotation speed, as the pressure oil source. When the oil pressure of the pressure oil source increases, there are problems in that the response speed of injection timing control becomes high, the injection timing becomes hunting, the exhaust purification performance and driving performance suddenly increase, and the noise increases.

The present invention has been made with the aim of solving these conventional problems.The present invention has been made in order to solve the problems of the prior art. Hunting can be prevented by providing a means for changing.

The present invention will be described in detail below based on the drawings.

FIG. 1 is a diagram showing an example of a diesel engine control device to which the present invention is applied.

In Fig. 1, an IFi air cleaner, 2 an intake pipe, 3
4 is the main combustion chamber, 4 is the swirl chamber, 5. is the glow plug, 6 is the injection nozzle, 7 is the injection pump (details will be explained later), and the exhaust pipe is
9 is a throttle valve that adjusts the amount of intake air; 10 is a diaphragm valve that controls the throttle valve iU; 11#'i is an EGR that controls the amount of bEGR flowing from the exhaust pipe 8 to the intake pipe 2 (exhaust gas recirculation amount).
Valves 12 and 13 are solenoid valves. The trench 14 is a vacuum pump that serves as a negative pressure source, and can be used in common with a brake servo pump, for example. 15 is a constant pressure valve that creates a constant negative pressure from the negative pressure given from the vacuum pump 14; 16 is a battery; 11 is a glow relay that controls energization to the glow plug 5; and 18 is a control unit that controls the fuel injection amount of the injection pump 1. A servo circuit 19 is a glow lamp that indicates the energization state of the glow plug 5. 20 is an accelerator position signal I8. corresponding to the accelerator pedal position (it! angle) K. Accelerator position sensor that outputs 21t;j
: Crank angle sensor that outputs a reference pulse ■S2 for each reference crank angle (for example, 120°) and a unit pulse I85 for every unit angle f (for example, 1°); 22 indicates that the transmission is in the neutral position. A neutral switch that detects the current state and outputs a neutral signal IS4.
23 is a vehicle speed sensor that outputs a vehicle speed signal l85 (detected from the rotational speed of the output shaft of f continuous shooting) corresponding to the vehicle speed; 24t1;
A temperature sensor that outputs a temperature station signal ISg corresponding to the engine cooling water temperature; 25 is a lift sensor that outputs an injection start signal IS7 every time the injection nozzle 6 starts fuel injection; pl, for example, a switch activated by fuel pressure Or it is a piezoelectric element. Also, 26 is the atmosphere W which corresponds to the temperature and pressure of the atmosphere! This is an atmosphere Wj degree sensor that outputs a degree signal Sg. In addition, signals such as a sleeve position signal I89 (details will be described later) and a battery voltage signal l8LO are used, which correspond to the position of the sleeve that controls the fuel injection amount of the injection pump 7.

Further, 21 is an arithmetic unit, for example, a central processing unit (CP
U) 2B, a read-only memory (ROM) 29, a readable/writable memory IJ (RAM) 30, an input/output interface 31, and the like.

The arithmetic unit 21 receives each signal 1B1 to 1810 given from the various sensors mentioned above and a starter switch (not shown).
It inputs signals such as the starter signal ISu given from the starter motor (on when the starter motor is activated) and the glow signals I81, 2 given from the glow switch, and outputs various control signals osl to O87 for optimally controlling the diesel engine.

First, the crest valve opening control signal 081 and the WGR control signal 082
are pulse signals, and by controlling the duty of the electromagnetic valves 12 and 13 by changing the duty of these pulse signals, the opening of the throttle valve 9 and the opening degree of the EGB valve 110 are controlled.

Further, the fuel cutoff control signal 085 controls opening and closing of the fuel cutoff valve 11 (for stopping the engine) in the injection pump T.

Further, the fuel injection amount control signal 0811 and the sleeve position signal IS9 are given to the servo circuit 18, and the servo circuit 18 outputs the servo signal S1 so that both signals match, and the sleeve position is controlled by this servo signal S1. By doing so, the fuel injection amount is controlled.

Further, the fuel injection timing is controlled by controlling the injection timing control mechanism in the injection pump T using the injection timing control signal 085. Note that the injection timing is feedback-controlled using the injection start signal IS7 from the lift sensor 5.

By controlling the glow relay 11 using the glow control signal O86, the energization to the glow plug 5 is controlled.

Further, by controlling blinking of the glow lamp 19 using the glow lamp control signal 087, the energization state of the glow plug 50 is displayed. For example, the claw lamp 19 is turned on when the power is on, and turned off when the power is on.

Next, FIG. 2 is a sectional view of an example of the injection pump T.

In FIG. 2, fuel is first sucked from an inlet 32 of the pump body by a feed pump 34 driven by a drive shaft 33 connected to an engine output shaft.

The fuel discharged from the feed pump 34 is transferred to a pressure regulating valve 35.
The supply pressure is controlled and supplied to the pump chamber 36 inside the pump housing.

The fuel in the pump chamber 36 is sent to the high pressure plunger pump 38 through the suction boat 37 while lubricating the working parts.

This pump 3aO plunger 39 is connected to the drive shaft 33 and fixed to a nine eccentric disk 40, and is connected to the drive shaft 3 through a p1 joint 41.
3, it is driven in four phases according to the rotation of the engine.

It also has an eccentric disk 40II'i and the same number of face cams 42 as the number of engine cylinders, and is arranged on a roller ring 43 while rotating, and reciprocates by a predetermined cam lift each time the face cam 42 passes over nine rollers 44.

Therefore, the plunger 39 reciprocates while rotating,
Due to this reciprocating movement, the fuel sucked from the suction boat 37 is forced into the distribution boat 45 through the υ delivery valve 46 and into the injection nozzle 6 shown in FIG.

At this time, the fuel injection timing is freely adjusted by changing the relative position between the face cam 42 and the roller 44 using the low cylinder 43.

The roller ring 43 is connected to a plunger 48 via a driving pin 47.

In FIG. 2, plunger 4 is shown for convenience of explanation.
8 is rotated by 90 degrees, and the feed pump 34 is
At the same time, the axis is also shown rotated by 90 degrees.

The cylinder 49 containing the plunger 48 is connected to the casing 5
The oil chamber 51 is slidably housed inside the cylinder 49, and an oil chamber 51 is defined at the right end of the cylinder 49, and an oil chamber 52 is formed at the left end. A round orifice 49m and a passage 50a are provided which communicate the oil chamber 51 and the end face high pressure chamber 55 when the cylinder 49 moves to the right.

The oil chamber 51 communicates with the other oil chamber 52 and the suction side of the feed pump 34 through a fuel passage 53, and an orifice 53a and a solenoid valve 54 are provided at the connection between the oil chamber 51 and the fuel passage 53. ing.

The fuel pressure of the pump chamber 36 is introduced to the high pressure chamber 55 of the end face of the plunger 48 sliding in the cylinder 49 which has been opened through the orifice 56a and the passage 56, and the opposite low pressure chamber 5T is connected to the high pressure chamber 55 of the feed pump 34. Although it communicates with the suction side and is in a state close to negative pressure, the plunger 48 is pushed back by the elastic force of the spring 58.

Since the fuel pressure in the pump chamber 36 increases in proportion to the rotational speed of the feed pump 340, the orifice 4
When the plunger 48t is closed, the plunger 48t is pushed to the left in the drawing as the engine speed increases, and this causes the roller ring 43 to rotate in the opposite direction to the rotational direction of the eccentric disk 400, so that the injection The timing becomes earlier depending on the rotation speed.

In addition, the cylinder 49 moves fully to the right in the drawing due to the rotational force of the eccentric disk 400 (at this time, the solenoid valve 5
4 is opened), the oil chamber 51 and the end face high pressure chamber 55 communicate with each other via the orifice 49m and the passage Set, so by opening and closing the solenoid valve 54, the end face high pressure 3i! S
The pressure of S can be controlled. Furthermore, if the opening and closing of the solenoid valve 54 is duty-controlled using the injection timing control signal 085, the injection timing can be electrically controlled.

Next, how the plunger 48 responds when the solenoid valve 54 is turned on or off will be explained in detail.

We will explain the response to the advance angle node.

When the solenoid valve 54 is open, oil flows through the orifice 56.
a. When the solenoid valve 54 is closed in this state, the oil N51 enters the end face high pressure chamber 55 and the oil ms1 via the orifice 49m and the passage 50m, and moves to the low pressure side via the orifice 53m and the fuel passage 53. It becomes impossible to escape to the low pressure side through the orifice 5s feeling. At this time, the end face high pressure N55
And oil! ! 51 through the orifice 48m and the passage Sea, the hydraulic pressure in the compartment becomes strong.

Since the oil pressure applied to the rounding cylinder 411 is in a well-balanced state, the cylinder 49 moves to the left (advance angle @) in the drawing by the force of the spring 51a.

Oil flows into the end face high pressure N55 through the oriice 56m until the plunger 48 is in a balanced state against the force of the tf-spring 580, and the granger 48 moves to the left in the drawing to advance.

Next, the response to the retard side will be explained.

When the solenoid valve 54 opens, oil! 151 oil is orifice 53
The cylinder 49 moves to the right in the drawing because it escapes to the low pressure side through the field. The end face high pressure chamber 55 and the oil chamber 51 communicate with each other through the 70 rounded orifice 49a, passage 50a and K, and the end face high pressure 1 isso oil escapes to the low pressure side, so the plunger 48 moves to the right in the drawing and retards the angle.

As described above, the response of the plunger 48 when the electromagnetic valve 54 opens and closes is rate-limited by the orifice 56m when the angle is advanced, and is rate-limited by the orifices 49a and 53m when the angle is retarded. In other words, the response speed is determined by the oil inflow and outflow speeds.

On the other hand, the amount of fuel to be injected is determined by the position of the sleeve 60 that covers the spill boat 59 formed on the plunger 39. For example, when the opening of the spill boat 59 passes over the right end of the sleeve 60 due to the rightward movement of the plunger 39, the fuel that had been pumped from the plunger pump chamber 61 to the distribution boat 45 is transferred to the spill boat 59.
11 and is released into the pump chamber 36, thus ending the pumping.

That is, when the sleeve 60 is displaced rightward relative to the plunger 39, the fuel injection end time is delayed and the fuel injection amount is increased, and when the sleeve 60 is displaced leftward, the fuel injection end time is advanced. This results in a decrease in the amount of fuel injected.

The position control of the sleeve 60 described above is performed by a servo motor 62. That is, the shaft s3 of the servo motor 620 is threaded, and a slider 64 having a threaded hole in the center is screwed therein.

A link lever 65 is coupled to this slider 64 so as to be rotatable about a bin 66 as a fulcrum.

The link lever 65 is rotatably attached around a fulcrum 67, and locks the sleeve 60 via a pivot pin T2 at the tip of the link lever (-65).

Therefore, when the servo motor 62 rotates forward and backward, the slider 64 moves left and right, so that the link lever 65 rotates about the fulcrum 67, causing the sleeve 60 to move left and right.

The servo motor 620 is controlled by the fuel injection amount control signal osi
, by the servo signal S1 outputted by the servo circuit 18 in response to .

Therefore, there is no direct correspondence between the accelerator pedal and the fuel injection amount. In other words, the accelerator pedal is
It is only a means of conveying the driver's intention of "wanting to accelerate" or "wanting to decelerate" to the computing device 2T, and the computing device 2T
However, the optimal fuel injection amount is calculated according to the operating state at that time, and optimal control is performed using the fuel injection amount control signal 0811.

Further, the shaft of a potentiometer 68 provided near the servo motor 62 is coupled to the shaft 63 of a servo motor 620 by gears 69 and 70, so that the signal from the potentiometer 68 indicates the position of the sleeve 60.

This signal becomes the sleeve position signal I89.

On the other hand, the electromagnetic dust fuel cut-off valve 71#'i is controlled to open and close by the fuel cut-off control signal os5, and when cut off, the suction valve 71#'i is closed and the fuel is cut off, thereby stopping the engine. It has become.

The present invention relates to the control of injection timing, and when applied to a diesel engine, it relates to the control of the solenoid valve 54 shown in FIG. 2. Note that the present invention is applicable not only to diesel engines but also to gasoline engines.

This will be explained in detail below.

FIG. 4 is a block diagram of one embodiment of the present invention.

In FIG. 4, the counter 105 receives the reference pulse IS2. from the crank angle sensor 21. A unit pulse IS5 that is set at a given point in time and input from that point onwards.
is counted, and the injection start signal IS7 is sent from the lift sensor 25.
It is reset when given.

Therefore, the output of the counter 105 corresponds to the crank angle from the reference position to the position where fuel injection is actually performed, and is a round value, that is, a value relative to the actual value of the injection timing.

This value is converted into an analog signal by the DA converter 106, and sent to the differential amplifier 108 as an actual value signal T indicating the actual value of the injection timing.

On the other hand, the target value calculation circuit 101 is, for example, a function generation circuit, and calculates the engine rotational speed calculated from the unit pulse IS5 and the potentiometer 68 (corresponding to the same reference numerals in FIG. 2).
The sleeve (
The optimum target value of the injection timing is calculated from the actual position (value corresponding to the injection amount) of 60) in FIG. 2, and a corresponding target value signal ITB is output.

The relationship between the rotational speed, sleeve position, and target value is as follows:
For example, as shown in FIG. The curve in FIG. 5 is a target value curve, and the value increases in the direction of the arrow.

Next, the differential amplifier 108 calculates the deviation ΔIT between the target value signal IT and the actual value signal IT (ΔIT=IT, −IT
-) is output.

Next, the variable time constant integrator 109 outputs an integral signal S6 that integrates the deviation ΔIT, but at this time, the pump m in FIG.
The rotational speed f of the engine is related to the fuel pressure in the ali (hereinafter referred to as pump internal pressure) (rotational speed and pump internal pressure are
The integration time constant is automatically changed according to the characteristics shown in the figure. Therefore, the unit pulse IS5 of the crank angle cent t21 is converted into a rotational speed signal via the (b) plate speed signal generation circuit 118, and after rounding, the variable time constant integrator 1
It is input in 09. Note that details of the variable time constant integrator 109 will be described later.

Next, the comparator 111 generates a pulse signal having a duty ratio proportional to the value of the integral signal S6 by comparing the dither signal (triangular wave) given from the dither generator 110 and the above-mentioned integral signal S6. Output. This pulse signal is output as the injection timing control signal O85, and the transistor Q1
By opening and closing the drive circuit, which consists of Feedback control can be performed to match the

Next, variable time constant integrator 101B will be explained in detail.

FIG. 7 is a diagram showing an embodiment of the variable time constant integrator 108.

In FIG. 7, the rotational speed signal generation circuit 118 receives the unit pulse IS5 of the crank angle sensor 21, increases the rotational speed, and outputs a nine voltage N (rotational speed signal).

Comparators 113 and 114 each have a reference voltage V11V.
2 (Vl<V2) and N are compared, and when N is larger, a signal 88.89 that goes high level is output.

The switching circuits 115 and 118 are turned off when the signal S8 or S9 respectively becomes high level.

On the other hand, the operational amplifier 111, the capacitor C1, and the resistor R1
~R5 constitutes an integration circuit, and its integration time constant RC
1 (however, the combined resistance of RFiR and ~R5).

Therefore, the integration time constant changes as follows according to the change in R.

First, if ■1<v2≦N, the switching circuit 11
Since both 5 and 116 are off, R=R.

The integral time constant is RIC.

Next, in the case of v1≦N<V2, a switching cycle occurs.

becomes.

That is, the larger N becomes, the larger the integral time constant becomes.

Since the N(D voltage becomes higher as the rotational speed increases, the integral time constant becomes larger as the rotational speed increases, and accordingly, as the pump internal pressure increases.

This rounding makes it possible to prevent hunting in injection timing control when oil pressure increases.

In the above embodiment, the integration time constant is changed in three stages, but it is also easy to subdivide the integration time constant into three stages.

FIG. 8 shows another embodiment.

In this embodiment, a pressure jump-up 121 for detecting the fuel pressure inside the pump W136 is attached to the bomb nose housing of the injection pump 1.
By inputting the pressure start-up signal to the divider 109, the integral time constant is changed based on the pump internal pressure. That is, the integral time constant is directly changed by the pump internal pressure signal P instead of the rotational speed signal N of the above-described embodiment.

FIG. 9 shows yet another embodiment.

In this embodiment, instead of directly detecting the pump internal pressure, the pressure regulating valve 350 stroke (position) related to the pump internal pressure is detected.
is detected and the integral time constant is changed based on this. That is, a non-contact displacement meter (gap sensor) 131 is provided near the pressure regulating valve 35, and its gap signal xs111 is inputted to the pressure regulating valve stroke signal generation circuit 132 to obtain the pressure regulating valve stroke signal.
This is inputted to the variable time constant integrator 109 via the subtracter 133. Here, the relationship between the pump internal pressure and the stroke L of the pressure regulating valve 350 is as shown in FIG.

By subtracting L and L, the value of LQ-L becomes a value proportional to the pump internal pressure, so it can be used in place of the above-mentioned N or P.

As explained above, according to the present invention, when the oil pressure of the pressure oil source of the injection timing control mechanism is large, the control signal is changed gradually, so hunting in the 5th stage control during injection can be prevented.
Smooth control is possible.

Therefore, it is possible to improve exhaust gas purification performance and driving performance, and there are effects such as being able to reduce noise.

[Brief explanation of drawings]

Fig. 1 is a diagram of an example of a control device for a diesel engine to which the present invention is applied, Fig. 2 is a sectional view of an example of an injection pump, and Fig. 3 is a sectional view of an example of an injection pump.
Figure 4 is a block diagram of an example of an injection timing control system, Figure 4 is a block diagram of an embodiment of the present invention, Figure 5 is a characteristic side diagram of the injection timing target value, and Figure 6 is a diagram showing the relationship between rotational speed and pump internal pressure. Characteristic side diagram, Fig. 7 is an embodiment diagram of the variable time constant integrator of the present invention, Fig. 8
9 and 9 are sectional views of injection pumps showing other embodiments, respectively, and FIG. 10 is a characteristic side view of the internal pressure of the pump and the stroke of the pressure regulating valve. T...Injection pump 21...Crank angle sensor 2
5... Lift sensor 2T... Arithmetic device 34
...Feed pump 35...Pressure regulating valve 3
6...Pump chamber 38...High pressure plunger pump 39...Plunger 42...Face cam
43...Roller ring 44...Roller 41
1...Plunger 49...Cylinder 49m
... Orifice 50 ... Casing 51,
52...Oil chamber 51m...Spring 53...
Fuel passage 53m... Orifice 54... Solenoid valve 55... End face high pressure m S&... Passage
51...Low pressure iti sa...Spring
101... Deviation detection circuit 102... Control circuit (integrator circuit) 103... Injection timing control mechanism 1
04...Sensor 105...Counter 106...
・DA converter 107...Target value calculation circuit 108・
・Differential width increase! ! 109... Variable time constant integrator 110... Dither oscillator 111. '113L
114... Comparator 115, 116... Switching circuit 111... Arithmetic layer intermediate unit 116...
Rotational speed note generation circuit 121... Pressure big up 122... Pressure signal generation circuit 131... Non-contact displacement needle (gap sensor) 132... Pressure regulating valve stroke signal generation circuit 133... Subtractor IS
2...Reference pulse IS5...Unit pulse I
S7...Injection start signal l515...Pressure big up signal 18114...Gap signal
IT,...Target value signal IT,...li! Actual value signal ΔIT... Deviation S6... Integral signal
N...Rotation speed signal P...Pressure signal L...
・Pressure regulating valve stroke signal O85...Injection timing control signal Patent applicant Nissan Motor Co., Ltd.

Claims (1)

[Claims] In a fuel injection timing control device for an internal combustion engine that controls a fuel injection timing control mechanism using hydraulic pressure using a signal that integrates a deviation between a target value and an actual value of fuel injection timing, an integral time constant of a circuit that integrates the deviation 9%, comprising means for changing the oil pressure in accordance with the oil pressure of the pressure oil source of the fuel injection control mechanism;
Internal combustion engine O fuel injection timing control device.