JPH02245445A - Fuel injection control device for internal combustion engine - Google Patents

Abstract

PURPOSE:To enable the proper control of an air-fuel ratio at the time of the selection of valve timing by correcting a detected load value used for the calculation of a fuel amount when the valve timing is selected for at least one of intake and exhaust valves with a valve timing variable means. CONSTITUTION:In an internal combustion engine equipped with the valve timing variable means A wherein rocker arms for high and low speeds are engaged with a rocker shaft, and a connection condition between the rocker arms is selected with a hydraulically actuated connection selector mechanism for selecting valve timing, a fuel amount calculation means B calculates a fuel amount according to the variable means A and a load detecting means C for detecting an engine load condition. In this case, a selection detecting means D is provided for detecting whether valve timing is selected with the variable means A. When the selection is made, a correction means E is made to correct a load value detected with the load detecting means C.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Application Field) The present invention relates to a fuel injection control device for an internal combustion engine, and particularly to a fuel injection control device for an internal combustion engine having a variable valve timing mechanism that can change the valve timing of an intake valve or an exhaust valve. This invention relates to an injection control device.

(Prior Art and Problems to be Solved by the Invention) A so-called variable valve timing mechanism that can vary the characteristics of the intake valve or exhaust valve system of an internal combustion engine uses low-speed valve timing in the low-to-medium rotation range, and uses low-speed valve timing in the high-speed rotation range. By automatically switching to high-speed valve timing, the valve timing is switched so that high output can be drawn over a wide range from low-speed to high-speed range without causing a decrease in output in the low-speed range, and the applicant has First, the valve timing of at least one of the intake valve and the exhaust valve can be freely switched between low-speed valve timing (low-speed V/T) suitable for a low-speed range and high-speed valve timing (high-speed V/T) suitable for a high-speed range. In an engine with a variable valve timing mechanism, the optimum valve timing is set according to the operating condition, and the amount of fuel corresponding to the valve timing is determined based on load parameters such as intake pipe internal pressure and engine speed. In order to control the engine based on the amount of fuel, the valve timing is switched at the point when the engine output obtained with low-speed valve timing and the engine output obtained with high-speed valve timing approximately match. In this engine, we proposed a valve timing switching control that switches the valve timing when the fuel injection amount set according to the low-speed valve timing and the fuel injection amount set according to the high-speed valve timing almost match. (Patent Application No. 63-102239, etc.).

Such valve timing switching control can reduce switching shock when switching valve timing, but there is still room for improvement in the following points. Therefore, when a change in volumetric efficiency occurs, the amount of fuel is determined as described above based on the detected load parameter value.In general, a detection means (sensor) that detects the load parameter, such as the absolute pressure in the intake pipe, is used to determine the amount of fuel. 1) B^
Sensors often employ a method of smoothing the detected signal to prevent noise, and in this case, the fuel amount is calculated based on the smoothed signal.

However, the absolute pressure P8 in the intake pipe varies due to the change in volumetric efficiency when switching the valve timing.
At this time, there is a delay in the detected value of the PB^ sensor, so due to the characteristics of such Pa^ sensors, it is difficult to accurately measure the fluctuations in the intake pipe absolute pressure PB^ (actual Pa^) as described above. Therefore, it is difficult to detect the change in the air-fuel ratio (A/F) after switching the valve timing, which may have a large effect on characteristics such as emissions. In other words, in operating conditions where the intake pipe absolute pressure PB^ fluctuates rapidly due to valve timing switching, the fluctuation of G air supplied to the cylinder due to the change in volumetric efficiency caused by the valve timing switching during the transition period is suppressed. It is difficult to detect, and optimal A/F control cannot be performed due to the delay in detecting the actual Pa^, which may lead to worsening of emissions or torque shock.

The present invention has been made in view of the above points, and provides a fuel for an internal combustion engine that can appropriately control the amount of fuel supplied even when switching valve timing, improve emissions, and suppress torque fluctuations. The purpose of the present invention is to provide an injection control device.

(Means for Solving the Problems) In order to achieve the above object, the present invention provides a variable valve timing means for variably controlling the valve timing of at least one of the intake and exhaust valves according to the operating state of the internal combustion engine; load detection means for detecting the load state of the
A fuel injection control device for an internal combustion engine, comprising: a fuel amount calculation means for calculating a fuel amount in response to outputs of the valve timing variable means and the load detection means; and a fuel supply means for supplying the fuel amount to the internal combustion engine. , a switching detection means for detecting that the valve timing has been switched by the valve timing variable means; and a correction means for correcting the load detection value 1):j when the switching is detected by the switching detection means. It is designed to provide the following.

(Example) Hereinafter, one embodiment of the present invention will be described in detail based on the accompanying drawings.

FIG. 1 is an overall configuration diagram of a fuel supply control device for an internal combustion engine to which the control device of the present invention is applied. In the figure, 1 is a DOIIC in which each cylinder is provided with a pair of intake valves and an exhaust valve.
:It is an in-line 4-cylinder internal combustion engine.

The engine l has an intake pipe 2 with an air cleaner I7 attached to its open end, and an exhaust pipe 2. +8 is connected.

A throttle body 3 is provided in the middle of an intake pipe 2 of an engine 1, and a throttle valve 3' is arranged inside the throttle body 3. Throttle valve 3' has throttle valve opening (θth)
A sensor 4 is connected to the throttle valve 3', and outputs an electric signal corresponding to the opening degree of the throttle valve 3' and supplies it to an electronic control unit (hereinafter referred to as rEcUJ) 5.

A fuel injection valve 6 is provided between the engine l of the intake pipe 2 and the throttle body 3.

A fuel injection valve 6 is provided for each cylinder slightly upstream of the intake valve, and each injection valve is connected to a fuel pump (not shown) and electrically connected to the ECU 3 to control the ECU.
The valve opening time of fuel injection is controlled by the signal from 3.

Further, an electromagnetic valve 16 for performing lub timing switching control, which will be described later, is connected to the output side of the ECU 3, and the opening/closing operation of the electromagnetic valve 16 is controlled by the ECU 3.

On the other hand, an intake pipe absolute pressure (P8^) sensor 8 is provided immediately downstream of the throttle valve 3 via a pipe 7.
The absolute pressure sensor 8 converts the absolute pressure into an electrical signal.
The signal is supplied to the ECU 3.

Further, an intake temperature (l゛^) sensor 9 is installed downstream of the intake temperature (l゛^) sensor 9, which detects the intake temperature 'I゛^ and outputs the corresponding electric power 1.
No. 6 is output and supplied to ECU3.

Engine water temperature (1' w
) The sensor 10 is composed of a thermistor or the like, detects the engine water temperature (cooling water temperature) Tw, outputs a corresponding temperature signal, and supplies it to the ECU 3. An engine rotation speed (No.) sensor 11 and a cylinder discrimination (CYL) sensor 12 are attached around the camshaft or crankshaft of the engine 1. The engine rotation speed sensor 11 is one of the crankshafts of the engine l.
Pulse (TD) at a predetermined crank angle position every 80 degrees rotation
The cylinder discrimination sensor 12 outputs a signal pulse at a predetermined crank angle position of a specific cylinder, and each of these signal pulses is supplied to the ECLJ 5.

The ECU 3 is further connected to a vehicle speed sensor 13, a gear position sensor 14 that detects the shift position of the transmission, and other sensors and switches 15, and these detection signals are supplied to the ECU 3.

The ECU 3 includes an input circuit 5a having functions such as shaping input signal waveforms from various sensors, correcting voltage levels to predetermined levels, and converting analog signal values into digital signal values.
Central processing circuit (hereinafter referred to as r(:,PUJ>5b,
The storage means 5C stores various calculation programs executed by the CPU 5b, calculation results, etc., and includes an output circuit 5d that supplies drive signals to the fuel injection valve 6 and the electromagnetic valve 16.

The CPU 5b determines various engine operating states based on the various engine parameter signals described above, and adjusts the TD according to the following equation (1) according to the engine operating state.
Fuel injection time T of the fuel injection valve 6 synchronized with the C signal pulse
Calculate OUT.

'rouy="I" i XKI+2 ・-(1)
Here, i" i is the basic fuel amount, specifically the basic fuel injection time determined according to the engine speed Ne and the intake pipe absolute pressure Pa^, and for determining this 1゛i value. As a T i map, for low speed valve timing (1
'it map) and for high speed valve timing ('I'in'
Two maps (map) are stored in the storage means 5C.

K+ and NI2 are respectively a correction coefficient and a correction variable calculated according to various engine parameter signals, and are predetermined values that allow optimization of engine characteristics such as fuel consumption characteristics and engine acceleration characteristics according to engine operating conditions. determined.

C: The PU 5b further controls the opening and closing of the solenoid valve 16 by outputting a valve timing switching instruction signal using a method described later.

Based on the results calculated and determined as described above, the CPU 5b sends a drive signal to open the fuel injection valve 6 corresponding to the cylinder in which the intake stroke of the engine 1 starts and a signal to drive the solenoid valve 16 to the output circuit 5d. Output via.

In this embodiment, the 0; i ECU 3 is the engine l
A part of the valve timing variable means that variably controls the valve timing of the intake valve and exhaust valve according to the operating state of the valve timing variable means, the output of the valve timing variable means, and the Pa sensor 8. Ne
The valve timing is switched by a fuel amount calculation means that calculates the fuel amount in response to the output of the load detection means including the sensor ti, a part of the fuel supply means that supplies the calculated fuel amount to the engine l, and a valve timing variable means. When switching is detected by the switching detection means that detects that the load has been changed, the correction means is configured to correct the load detection value (see Fig. 2).
.

In this embodiment, the switching between high-speed valve timing and low-speed valve timing is performed by selecting a rocker arm and a cam as described below.

That is, FIGS. 3 and 4 show the main parts of a valve train equipped with such a variable valve timing mechanism for an engine 1.

Note that the figure shows the configuration of an intake valve-side valve operating device for opening and closing a pair of intake valves for one of four cylinders arranged in series in the cylinder block of engine l. , the intake valve side valve train in the cylinders a have basically the same configuration, and the exhaust valve side valve train for driving the pair of exhaust valves in each cylinder to open and close is also the same as the intake valve side valve train. It has basically the same configuration as the device.

The intake valve side valve operating device is housed and arranged in an operating chamber defined between the cylinder head and the head cover.
In the figure, the valve train 30 includes a camshaft 31 that is rotationally driven from a crankshaft (not shown) of an engine l at a speed ratio of l/2, and a camshaft 31 that corresponds to each cylinder.
A high speed cam 34 and a low speed cam 32 and 33 provided in
a rocker shaft 35 fixedly arranged parallel to the camshaft 31; a first drive rocker arm 36, a second drive rocker arm 37, and a free rocker arm 38 that are pivotally supported on the rocker shaft 35 in correspondence with each cylinder, respectively;
A connection switching mechanism 39 is provided between each rocker arm 36, 37, 38 corresponding to each cylinder.

In FIG. 4, the connection switching mechanism 39 includes a first switching bin 41 that can connect the first driving rocker arm 36 and the free rocker arm 38, and a 21i1J switching bin that can connect the free rocker arm 38 and the second driving rocker arm 37. 4
2, a regulation bin 43 that regulates the movement of the first and second switching bins 41 and 42, and a return spring 44 that urges each of the bins 41 to 43 toward the disconnection side.

The first drive rocker arm 36 includes a free rocker arm 38.
A first guide hole 45 with a bottom and open to the side is bored parallel to the rocker shaft 35, and the first switching bin 41 is slidably fitted into the first guide hole 45, and the first switching bin 41 is slidably fitted into the first guide hole 45. A hydraulic chamber 46 is defined between one end of the guide hole 41 and the closed end of the first guide hole 45 . Moreover, the first drive rocker arm 36 is provided with a passage 47 that communicates with the hydraulic chamber 46, and the rocker shaft 35 is provided with an oil supply passage 48. It is constantly communicated with the hydraulic chamber 46 via 47.

A guide hole 49 corresponding to the first guide hole 45 is provided in the free rocker arm 38 so as to extend downward from the rocker shaft 35 and extend between both sides, and one end thereof is brought into contact with the other end of the first switching pin 4I. The second switching bin 42 is in the guide hole 49
is slidably fitted to.

The second drive rocker arm 37 has a bottomed second guide hole 50 corresponding to the guide hole 49 in the free rocker arm 3B.
A disc-shaped regulation bin 43, which is open to the side and is bored parallel to the rocker shaft 35 and comes into contact with the other end of the second switching bin 45, is slidably fitted into the second guide hole 50. Moreover, a guide tube 51 is fitted into the closed end of the second guide hole 50, and a shaft portion 52 that is slidably fitted into the guide tube 51 is coaxially and integrally protruded with the regulation bin 42. Ru. Also, the return spring 44 is connected to the guide cylinder 51 and the guide 11il + the bottle 43.
This return spring 44 allows each bottle 4 to
1, 42, and 43 are urged toward the hydraulic chamber 46 side.

In this connection switching mechanism 37, as the hydraulic pressure in the hydraulic chamber 46 increases, the first switching bin 41 fits into the guide hole 49, and the second switching bin 42 fits into the second guide hole 50, so that each Rocker arms 36, 38, 37 are connected. When the oil pressure in the hydraulic chamber 46 becomes low, the spring force of the return spring 44 causes the first switching pin 41 to return to the position where the contact surface with the second switching pin 42 corresponds between the first drive rocker arm 36 and the free rocker arm 38. Second switching pin 42
is returned to the position where the contact surface with the regulation bin 43 corresponds between the free rocker arm 38 and the second drive rocker arm 37, so that the connected state of each rocker arm 36, 38° 37 is released.

The oil supply path 48 in the rocker shuttlecock 5 is connected to an oil pump 28 via a switching valve 27.
By the switching operation 7, the oil pressure in the oil supply passage 48, and thus the oil pressure in the oil pressure chamber 46 of the connection switching mechanism 39, is switched between high and low levels. This switching valve 27 is connected to the electromagnetic valve 16, and the switching operation of the switching valve 27 is controlled by the ECU 3 via the electromagnetic valve 16.

The switching valve 27 also detects oil pressure and turns on when the pressure is low.
A hydraulic switch 60 is provided that turns off when the pressure is high. The oil pressure switch 60 is included in the switches 15 in FIG.

'' The intake side valve operating device 30 of the engine I, which is configured as a double series, operates as follows. Note that the exhaust side valve train operates in the same manner.

When the ECU 3 outputs a valve opening ta signal to the solenoid valve 16, the solenoid valve 16 is opened, the switching valve 27 is opened, and the oil pressure in the oil supply passage 48 is increased. As a result, the connection switching machine tM 39 is operated and each rocker arm 36, 3
8.37 is in the connected state, and the high speed cam 34
Each rocker arm 36゜38.37 operates as a third
In this state (a shown), the pair of intake valves 40 are shown in the figure.
The valve opens and closes at high-speed valve timing with a relatively large opening period and lift amount.

On the other hand, when a valve closing command signal is output from the ECU 3 to the solenoid valve 16, the solenoid valve 16 and the switching valve 27 are operated to close.
The oil pressure in the oil supply path 48 becomes low. As a result, the connection switching mechanism 39 operates in the opposite manner to the above, and each rocker arm 36, 38
．． 37 is released, the corresponding rocker arms 36 and 37 are operated by the low speed cams 32 and 33, and
The pair of intake valves 40 operate at low valve timing with a relatively small valve opening period and lift amount.

Next, valve timing switching control according to the present invention will be explained.

The valve timing (V/"1") switching point can be set as follows.

That is, for example, the switching conditions for switching from low-speed valve timing to high-speed valve timing are as follows.

■'1' i L map value for low speed valve timing and Tin map value for high speed valve timing are the same point ■N u or r ('r when N e < NVTLMT
In vt=/(N e ), 'I'our)'
1" VT ■ When NVTLMT<N e, Nll0F, NVTLlIT is the predetermined engine rotation speed shown in FIGS. 7 and 8, which will be described later.
l'VT is a high load determination value.

Valve timing switching is basically based on the absolute pressure in the intake pipe.
) Ro^, each map ( depending on the engine speed Ne
Search for the TiL map for low-speed valve timing and the "l'in map for high-speed valve timing" and select the larger i'
A method is adopted in which valve timing is selected according to the i value.

To describe this in detail below, first, in FIG. 5, the Ti value of the TiL map for low speed valve timing is shown as a solid line, and the 1'i value of the 'l''in map for high speed valve timing is shown as a dotted line. However, as is clear from the figure, the rate of increase in intake air amount decreases at low valve timings that are slow to increase with engine speed Ne, while the rate of increase in intake air amount decreases as the engine speed Ne increases at high valve timings. Since the intake air amount exceeds that of the low-speed valve timing, the ′!゛i value for the low-speed valve timing and the ′l″1Il value for the high-speed valve timing are changed in the middle.
11 matches.

In this state, the intake air amount is the same and the air-fuel ratio is the same regardless of whether the valve timing is low or high, so the engine output is between the two.

Note that the charging efficiency slightly fluctuates with changes in the engine speed Ne, and this fluctuation becomes noticeable as the throttle opening degree θt,b approaches full opening.

FIG. 6 is an enlarged view of this state, where the Ti value for low-speed valve timing and the i' i value for high-speed valve timing are equal at multiple points, and as will be described later, the Ti value for low-speed valve timing is equal to the i' i value for high-speed valve timing. 'I' for i value and high speed valve timing! If the valve timing is switched at a point where the i value becomes equal, hunting in the valve timing switching is likely to occur in the high throttle opening range, and the durability of the connection switching mechanism 39 is adversely affected.

By the way, in the high load range (OTL - fully open range), the high load increase coefficient KIII included in the coefficient Kl in the above equation (1)
The air-fuel mixture is enriched by OT, and in such a high load range, it is better to switch to high-speed valve timing to increase output, so when the engine is in a high load range (θth fully open range), the timing shown in Figure 7 The high load judgment value '1' v r based on the fuel injection amount is experimentally determined as follows, and T
'r'v according to engine speed Ne from vr table
Calculate the value of y and find 'I' out '! When the value exceeds VT, the valve timing is switched to high-speed valve timing as described later.

In this case, if the region where i'ouτ≧'I''VT includes the region where the Ti values of the low-speed valve timing and the high-speed valve timing in the high throttle opening range described above match, then the above-mentioned valve timing switching hunting can be prevented.

Please note that automatic cars and manual cars are different.
Use VT table.

Also, in order to prevent engine overspeed, fuel is cut when the engine speed Ne exceeds the rev limiter value NIIFC, but considering the load acting on the timing belt, the valve opening time becomes shorter. The acceleration during the opening operation of the valve increases, and the load on the timing belt increases, and the increased acceleration also lowers the engine rotational speed Ne, which causes valve jump. Therefore,
The allowable rotational speed also differs between low-speed valve timing with a short valve-opening period and high-speed valve timing with a long valve-opening period.

Therefore, in this embodiment, the rev limiter value is set to a relatively low value (d1Nupc+ (for example, 7
500 rpm+w), and the high speed valve timing is set to a relatively high value Nopc2 (for example, 8100 rpm+).

Next, the valve timing switching characteristics will be explained with reference to FIG. In the figure, the solid line indicates the switching characteristic from low-speed valve timing to high-speed valve timing, and the dotted line indicates the reverse switching characteristic.

Valve timing switching is based on the lower limit rotation speed Ne+, where the engine output obtained with low-speed valve timing always exceeds the engine output obtained with high-speed valve timing, and the engine output obtained with high-speed valve timing exceeds the engine output obtained with low-speed valve timing. It is carried out in a region between the upper limit rotation speed Ne2 which always exceeds (condition of ■ above),
In this embodiment, hysteresis is added between switching from low-speed valve timing to high-speed valve timing and vice versa, and the Ne+ is adjusted to, for example, 480Orpm/4600r.
pm, Ne2 for example 5000rpm15700rpm
It was set to

The region marked X in the diagram is the engine's high load region (OLh fully open ° region)
The area where the valve timing is switched by comparing 'l' OUT and 'I'vr when it is in the Y area is 1)
; I shows the region in which the valve timing is switched by comparing the l'iL map for low-speed valve timing and the Tin value for high-speed valve timing.

Note that the switching characteristics in the region of FIG. 8, which takes the intake pipe absolute pressure 1)8^, cannot accurately represent the membrane characteristics, and the switching characteristics in the xfl region shown in the figure are for convenience.

Next, referring to FIG. 9, the valve timing switching control by the ECU 3, that is, the signal output to the solenoid valve 16)
The following describes the output control program. This program is executed in synchronization with each 'I' DC signal pulse.

In step 901, it is determined whether signals are being normally inputted to the ECU 3 from various sensors, or whether an abnormality has already occurred in the pond control system, that is, whether fail-safe should be performed.

Specifically, the intake pipe absolute pressure (Pa^) sensor 8, cylinder discrimination (CYL) sensor 12, engine rotation speed ('1'' DC
) Sensor 11, engine water temperature sensor lO1 vehicle speed sensor 1
3, abnormality in the ignition timing control signal output and fuel injection control output, valve timing control solenoid valve 16
An abnormality in the amount of current supplied to the valve timing control solenoid valve 16, a normal oil pressure change in the output Ll boat in response to the opening and closing of the valve timing control solenoid valve 16, which cannot be confirmed even after a predetermined period of time by the oil pressure switch 60 of the oil pressure sensor, etc. are detected. It is determined that the operating state of the engine is such that it should be fail-safe.

Note that if there is an abnormality in either the cylinder discrimination (CYL) sensor or the 1'DC sensor, the output of the other will be used to detect the abnormality.
Substitute the force output.

If the answer to step 901 is affirmative (Yes), that is, fail-safe should be performed, the process proceeds to step 904, which will be described later, and if the answer is negative (No), the process proceeds to step 902.

Step 902 is a step of determining whether or not the engine is being started based on the engine rotation speed Ne, etc., and step 003 is a step of determining whether the remaining time tst of the delay timer has reached O. (Step 9o4) is set to 5 seconds, for example, and the timing operation is started after startup.

In step 905, the engine water temperature T'w is the set temperature Tw+
Step 906 is a step of determining whether the vehicle speed is lower than (for example, 60 degrees Celsius), that is, whether warm-up has been completed. Step 907 is a step of determining whether the engine is low or not.
Step 908 is a step of determining whether the shift lever is in the parking (P) range or neutral (N) range in the case of an automatic vehicle (AT). , step 9
00 is a step to determine whether the engine speed Ne is equal to or higher than the lower limit value Net of 0;j, and during failsafe (
If the answer to step 901 is 11 (Yes), during startup (if the answer to step 902 is yes), and after the start, the delay timer setting time tsr elapses 0:j (step 903
The answer to step 905 is affirmative (Yes)), the engine is warming up (the answer to step 905 is affirmative (Yes)), and the engine is stopped or slowing down (step 00
When the answer to step 908 is affirmative (Yes)), l), N range (the answer to step 908 is affirmative (Yes)), and Ne(
When Ne+ (the answer to step 909 is negative (No))
As will be described later, the solenoid valve 16 is closed to maintain the valve timing at a low speed valve timing.

n: When it is determined in step 909 that Ne≧Net holds true, in step 010, the "l" iL map and the "l'in map are searched, and the current engine speed No. and the absolute pressure in the intake pipe are determined. TiL map according to Pe^ (
7) Ti value (hereinafter referred to as 1'ic) and "I'in'
Tsubu (i') "l" i value (hereinafter referred to as 'rin)
Then, in step 9, 1'VT corresponding to the engine speed Ne is read from the Tvr table set for AT cars and MT cars, and in step 912, this l'v
Compare τ with 1'our of the previous loop, i' o
u r≧” “Determine whether or not vr holds true, that is, whether or not there is a high load state that enriches the air-fuel mixture. If the answer is negative (
NO), i.e. ′! ``0Ut ('l') When VT holds true, the process proceeds to step 913, where it is determined whether the engine speed Ne is equal to or greater than the upper limit value Ne2.

If the answer to step 913 is negative (No), that is, Ne(Ne2
When this holds true, the process proceeds to step 914, where TiL obtained in step 910 and I'in are compared.

As a result, when 'l'1L)l''in is established, it is determined whether or not the timer value 1.VTOFF of the delay timer set in step 915, which will be described later, is zero (step 916), and this answer is affirmative (step 916). If Yes), step 9
At step 17, a command to close the solenoid valve 16, that is, a command to change the valve timing to low speed is issued. Also, 1”0IJT≧i’v
r, Ne≧N (32, When either 'l''iL≦'f''in holds true, 11; 1 solenoid valve opening delay
Timer 111 (for example, VTOFF (for example, 3
seconds) and start (step 915).
In step 918, a command to open the i[Jt valve 16, that is, a command to change to high-speed valve timing (9) is issued.

When the valve closing command is issued in step 917, it is determined in step 019 whether the oil pressure switch 60 has been turned on, that is, whether the oil pressure in the oil supply path has become low pressure. If the answer is affirmative (Yes), that is, the oil pressure switch 60 is turned on, it is determined in step 921 whether or not the remaining time 111J+, tvt of the low speed valve timing switching delay timer has become 0.

If the answer to step 021 is affirmative (Yes), tLVT=
When it becomes O, the remaining time tuvτ of the high-speed valve timing switching delay timer is set to a set time (for example, 0.1 seconds) in step 923, and then used in the fuel injection control routine in step 925. The TiL map and the ignition timing map for low-speed valve timing (θigL map) are selected as the 'ri map and ignition timing map, respectively, and in the following step 927, the rev limiter value NIIFC is changed to the value f' for low-speed valve timing.
J++pct processing is performed.

On the other hand, when the valve opening command is issued in step 918 of O:J, it is determined in step 920 whether the oil pressure switch 60 has been turned off, that is, whether the oil pressure in the oil supply path has become high pressure. If the answer is affirmative (Yes), that is, the oil pressure switch 60
When OFF, it is determined in step 922 whether the remaining time r, 1IVT of the high-speed valve timing switching delay timer has become 0.

If the answer to step 922 is affirmative (Yes), tuvr=
When it becomes 0, the remaining time LLvr of the low-speed valve timing switching delay timer is set to a set time (for example, 0.2 seconds) in step 924, and then in step 926.
In step 928, the i'in map and the ignition timing map for high-speed valve timing (Qigu map) are respectively selected as the l'i map and ignition timing map used in the fuel injection control routine, and in the subsequent step 928, Nupc is selected. Processing is performed to set the value NIIFC2 for high-speed valve timing.

By the way, the above-mentioned double switching delay timer t, IIVT
.

The LVT setting time is adjusted to the response delay time from when the solenoid valve 16 is opened and closed until the switching valve 27 switches, the oil pressure in the oil supply path changes, and the switching operation of the connection switching mechanism 39 for all cylinders is completed. When the solenoid valve 16 is switched from open to idle, the program goes through steps 910 → 922 → 924 → 92 until the oil pressure switch 60 is turned on.
6 → 928, and even after turning on, until the connection switching mechanism 39 of all cylinders is switched to the low speed valve timing side,
Proceed in the order of steps 919 → 921 → 926 → 928,
Furthermore, if the switching valve 27 does not switch to the closing side even if a valve closing command is issued due to a failure of the solenoid valve 16 or the switching valve 27, and the oil pressure switch 60 does not turn on for a long time, the same procedure as described above is performed in step 910→ The process progresses in the order of 922 → 924 → 926 → 928, and until the connection switching mechanism 39 of all cylinders is eventually switched to the low speed valve timing side, the fuel injection control is maintained to be compatible with the high speed valve timing.

When the solenoid valve 16 is switched from closed to open, the fuel injection control is adapted to the low-speed valve timing in the same manner as described above, unless the connection switching mechanism 39 for all cylinders is switched to the high-speed valve timing side. maintained.

On the other hand, the answer to step 902 is affirmative (Yes), or the answer to step 11;
(Yes), that is, when the engine is starting, when the set time has elapsed after starting 1fij, during one fold, when the engine is stopped I, or when the engine is slowing down,
Proceeding to step 929, issue a valve closing command to the solenoid valve 16,
From step 9, the process proceeds in the order of steps 923→925→927.

If the range is N or P in step 908, the process proceeds to step 930 to determine whether or not the 1'in map was selected in the previous loop. 030
Proceed to. When the answer to step 930 is 17 (Yes), that is, when the 1fii loop i'in map is selected, the timer value LVT (IFF of the solenoid valve opening delay timer) is set to 0; Step 931), the process advances to step 917, and if the answer to step 930 is negative (No), that is, if the Tin map was not used last time, in other words, the connection switching mechanism 39 for all cylinders is switched to the high-speed valve timing side. If not, the process proceeds in the same manner as above in the order of steps 929 → 923 → 925 → 927, and fuel injection control is performed in accordance with the low-speed valve timing, regardless of the oil pressure switch 60 in the oil pressure sensor.This is because the oil pressure switch 60 is This is a measure to take when the power is turned off due to a disconnection, etc.

By the way, the above-mentioned NIIPCI is set higher than Nez, and normally the valve timing is switched to high-speed valve timing before the engine speed Ne rises to Nupci, and the value of Nnpc is switched to NIIFC2. There will be no fuel cut.

In contrast, from steps 902 to 908 to step 92
In the operating state proceeding to step 9, even if the engine speed Ne exceeds Nez due to dry cooking or the like, the low valve timing is maintained, so that fuel cut is performed at NIIPCI. Furthermore, even when switching from low-speed valve timing to high-speed valve timing, fuel cut is performed at N II FCI until LIIVT becomes 0, that is, until the coupling mechanism 39 actually switches to the high-speed valve timing side.

Note that the ``I'iL map and Ti in step 910 above are
In the t+ map search processing subroutine, as shown in FIG.
While the TiL used in step 914 is the value retrieved from the Tit map, when the valve opening command is issued,
By performing processing to set TiL to a value obtained by subtracting a predetermined amount of hysteresis Δ゛1゛i from the search value, Y in FIG.
Hysteresis is added to the region switching characteristics.

Also, in the subroutine for calculating I'VT in step 911, as shown in FIG. If not, i used in step 912.
'V T is the value calculated from the 'l' VT table, while when a valve opening command is issued, 1'vt is the value obtained by subtracting the predetermined hysteresis amount Δ'l'V from the calculated value. In this way, hysteresis is added to the switching characteristics in the X region of FIG. 8.

Next, we will explain the
Explanation 1!11 is given with reference to the figure below.

The program subroutine shown in FIG. 12 is a flowchart in the case where the detected load Ps value from the intake pipe absolute pressure Pa sensor 8, which is one of the load parameters, is corrected when changing the valve timing. Specifically, the switching is aimed at correction when switching from low-speed valve timing to high-speed valve timing. This program is executed in synchronization with each generation of the "I" DC signal pulse.

In FIG. 12, step 1201 and the answer are affirmative (
In step 1204, which follows in the case of "Yes", it is checked whether or not the valve timing (V/T) has been switched. That is, first, in step +201, each time this program is executed, it is determined whether or not the current valve timing is high-speed valve timing, and when the answer is negative (NO), that is, when the valve timing at the time is low-speed valve timing. Then, the process proceeds to step 1202, where 1) the output of the sensor 8 is converted to Δ/l), and the converted value 1) is obtained.
Apply as is to the intake pipe absolute pressure 1) as 'I' and execute the i map search (step 1203).
, exit this program.

On the other hand, the answer to step 1201 of 11;1 is affirmative (
If Yes), that is, if the valve timing is high-speed valve timing, then in the subsequent step 204, it is further determined whether or not the previous valve timing was low-speed valve timing. However, the answer is affirmative (Y
In the case of es), that is, if the valve timing in the previous loop was low-speed valve timing, there is a change in valve timing between 0:1 and this time, and it is a change from low-speed valve timing to high-speed valve timing. , and at the time of the switching, step 120
Proceed to step 5 and use, for example, an up counter for setting the P o^ correction period when switching the valve timing, which is used for determination in step 1207, which will be described later. The timers t and v are reset.

In this way, this time the high-speed valve timing was changed to 11
; If low-speed valve timing is detected once (if the answers to steps 1201 and 1204 are affirmative (Yes)), the timer value of the timer evr is set to 0.

In addition, regarding the determination of which side the valve timing is, the ON/OFF information of the oil pressure switch 60 can be used as in the case of FIG. 9.

Next, in step 1206, a value correction is performed. The correction can be performed using a predetermined PB^ correction value ΔPVT for the Δ/D conversion value PB^^0,
In this program example, this is executed by adding ΔPVT, which takes a negative value, to the Pa^^D4ti.

Specifically, when the actual P8^ changes suddenly due to a change in volumetric efficiency due to valve timing switching, the 'I''i map (in this case, the 'I''in map) search is performed for the sudden change in Po^. In order to correct the Pa^ value to be used in accordance with the actual situation, a correction value ΔPVT is applied to the Pa^ sensor value, that is, the P B^^D value.

FIG. 13 shows an example of Pu^ correction in the case of switching from low-speed valve timing to high-speed valve timing.

As shown in the figure, if the horizontal axis is the engine speed Ne and the vertical axis is the intake pipe absolute pressure PH^, the valve timing will now shift from the low-speed valve timing state to the high-speed valve timing side at the ゛1'i coincidence point. If the switching occurs, after 01j of the point, the characteristics on the low-speed valve timing side and the characteristics on the high-speed valve timing side cross, and the vertical relationship in the figure is reversed. In this case, if the valve timing is not switched (therefore, there is no change in volumetric efficiency caused by it), the absolute pressure in the intake pipe will fluctuate rapidly as usual. However, in an engine with a variable valve timing mechanism, when switching as shown in the figure, the slope suddenly changes when shifting to the high-speed valve timing side (in this case, the slope changes from large to small). ).

Therefore, during such a transitional period, the actual intake pipe absolute pressure Pu^ (actual Pa^) has the sign I! As shown by the dashed-dotted line, tl [i shifts and then the characteristic shifts to the high-speed valve timing side.However, the PB^ sensor value shows a behavior in which the characteristics shift to the high-speed valve timing side.

Due to the detection delay as described above, the state will be as shown by the broken line with the symbol [11], and the actual P will remain unchanged for a certain period after switching.
It contains a deviation with respect to a^.

Therefore, in this program, even if the Ps^ sensor 8 has a detection output characteristic as shown by the broken line 11+, in step 1206 the above-mentioned A/
The P-correction value is subtracted from the D-conversion value Po^^0, and in this way, the I)D^ correction process is performed, and the obtained corrected PHA value, that is, P13^^0-ΔP
The vT value is applied to the 'l' i map search process, step 1203 is executed, and the program is ended.

In this way, the accuracy of the A/F control can be improved by searching the ``l''i map using the corrected P8^ value. Then, the timer tv・
This continues for a predetermined period of time measured by ``, and transient A/F fluctuations during that period are suppressed.In other words, from the next loop onwards, the process from step 1201 to step 1 is continued.
When the process proceeds to step 204, a negative (No) answer is obtained as a result of the determination.Thereafter, the process proceeds from step 1204 to step 1207, and the timer value of the Pa^ correction period defining timer evt is lower than the predetermined value evro (for example, 4 TDC period). Determine whether it is large or not. If the answer is negative (No), that is, evr≦evto holds true, and therefore a predetermined period of time has not passed since the switching, 0; step 1206. Execute step +203 and end this program.
On the other hand, if the answer of 1' (Yes) is obtained in step 1207, that is, if a predetermined period of time has elapsed, the above-mentioned I) mouth correction is canceled and O; step i +20.
2. Execute step 1203 and end this program.

From the above, 1) ROM sensor value is supplemented with correction value ΔPvr i
By applying lE, the actual P nA value can be detected with high accuracy even when switching valve timing.
It is possible to supply fuel commensurate with the air sucked into the cylinder. Therefore, in the case where no correction is performed, as mentioned above, after changing the valve timing,
While there was room for improvement in terms of emission changes and torque shock caused by A/F fluctuations, the present invention enables highly accurate A/F control and valve timing switching. This makes it possible to prevent an inappropriate amount of fuel from being supplied due to a delay in the detection of intake pipe internal pressure fluctuations. In this way, it is possible to improve emissions and suppress torque fluctuations due to A/F fluctuations, thereby significantly improving drivability.

As shown by reference numerals 12 and 112 in Fig. 13, when the valve timing limit in the high rotation range NVTLMT is exceeded, a considerably large difference appears and changes rapidly, so 11:1 piping numbers 1+, II+ Since the shock will be higher than that in the case of
The correction value used for the o^ correction may be changed, and it is more desirable to do so.

This program can be executed by being included in the process at step 910 in FIG.

In addition, in this embodiment, regarding the valve timing control of the intake valve and/or the exhaust valve, high-speed valve timing and low-speed valve timing are switched by rocker arm and cam selection, but the present invention is not limited to this. . For example, if the relative positions of the timing belt and the camshaft are shifted, or if each cylinder has a pair of intake valves and a pair of υ-air valves, as described above, one of these two valves! It may also be configured to stop the valve.

Furthermore, changing the valve timing does not only include changing the valve opening/closing timing of the intake and exhaust valves, but also includes changing the amount of lift, etc. in addition to this. In short, it includes all control elements that can change the characteristics of the intake/exhaust system.

(Effects of the Invention) According to the present invention, the intake
Valve timing for variably controlling the valve timing of at least one of the r-air valves (J variable means, 1): Load detection means for detecting the load state of the internal combustion engine, 1):
j) A fuel injection control device for an internal combustion engine, comprising: a valve timing variable means; a fuel amount calculation means for calculating a fuel amount in response to an output of the load detection means; and a fuel supply means for supplying the fuel amount to the internal combustion engine. , a switching detection means for detecting that the valve timing has been switched by the valve timing variable means; and when the switching is detected by the switching detection means, i); Since the device is equipped with a correction means, it is possible to prevent an inappropriate fuel amount from being supplied to 0 (zero) due to a detection delay in the detection means that detects the load parameter caused by switching the valve timing. Even when changing the valve timing, Δ/F can be appropriately controlled, emissions can be improved, and torque fluctuations can be further suppressed.

[Brief explanation of drawings]

1121 is an overall power structure diagram of a fuel injection control device for an internal combustion engine showing an embodiment of the present invention, FIG. 2 is a functional block diagram of the control system, and FIG. Figure 4 shows the inside of the connection switching mechanism including its switching control system. A cross-sectional view of an example of ¥-zukuri,
Fig. 5 is a diagram showing the basic fuel quantity setting characteristics for low-speed valve timing and high-speed valve timing, Fig. 6 is an enlarged view of the circled part in Fig. 5, and Fig. 7 is a diagram showing the "l" VT table. Figure 8 is a diagram showing the switching characteristics of valve timing, Figure 9 is a flowchart of IWJ switching valve control routine of valve timing, and Figure 10 is a flowchart of valve timing control routine.
11 is a program flowchart of a subroutine for searching the i'i++ map and the i'i++ map.
, FIG. 12 is a program flowchart 1 of the subroutine for P11^ correction processing shown as an example of the correction control of the load detection means 1, and FIG. Yes.!... Internal combustion engine, 3'... Throttle valve, 5.
...Electronic control unit (ECU), 6...Fuel injection valve, 6...Intake pipe absolute pressure sensor, 11...
Engine speed sensor, 16... Solenoid valve, 30...
Valve train, 39... Connection switching mechanism, 40... Intake valve.

Claims (1)

[Scope of Claims] 1. Valve timing variable means for variably controlling the valve timing of at least one of the intake and exhaust valves according to the operating state of the internal combustion engine; load detection means for detecting the load state of the internal combustion engine; A fuel injection control device for an internal combustion engine, comprising a valve timing variable means, a fuel amount calculation means for calculating a fuel amount in response to an output of the load detection means, and a fuel supply means for supplying the fuel amount to the internal combustion engine, A switching detection means for detecting that the valve timing has been switched by the valve timing variable means, and a correction means for correcting the load detection value when the switching is detected by the switching detection means. A fuel injection control device for an internal combustion engine, characterized by: 2. The fuel injection control device for an internal combustion engine according to claim 1, wherein the load detection means detects at least one of an intake pipe internal pressure and an engine rotational speed.