JPH11270369A - Valve timing control device of internal combustion engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve output of an internal combustion engine in accordance with a demand of a driver and secure a turnout traveling property even at the time of control abnormality of an internal combustion engine. SOLUTION: This control device is made fail safe as control in the direction to lower generating output is fundamentally carried out when control abnormality of an internal combustion engine 1 is detected, but when output improvement by a driver is demanded at this time, it is corrected in the direction to increase generating output in the driving state by a VVT(variable valve timing control mechanism) 10. Consequently, for example, it is possible to improve output in the internal combustion engine 1 even at the time when a throttle valve 14 is fixed in the neighborhood of total closing at the time of failure of an electronic throttle system and to secure a turnout traveling property.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a valve timing control apparatus for an internal combustion engine which can change the opening / closing timing or the lift of at least one of an intake valve and an exhaust valve of the internal combustion engine in accordance with an operation state. .

[0002]

2. Description of the Related Art Conventionally, as a prior art document relating to a valve timing control device for an internal combustion engine, Japanese Patent Laid-Open No. 5-12 / 1993
One disclosed in Japanese Patent No. 5966 is known. This system has at least two cams of low output and high output in order to control the opening / closing timing and lift amount of an intake valve or an exhaust valve of an internal combustion engine, and a control abnormality such as malfunction of the throttle valve has occurred. At times, there is disclosed a technique for reducing the output generated by an internal combustion engine by switching a cam.

[0003]

By the way, in the above-mentioned system, for example, a so-called electronic drive for driving an actuator so that the throttle opening of the throttle valve matches the target throttle opening indicated by the accelerator operation amount or the like. When the throttle system is provided and the throttle valve is broken and fixed near the fully closed position, the output generated by the internal combustion engine is reduced, so that there is a problem that the evacuation traveling performance cannot be satisfied.

Therefore, the present invention has been made to solve such a problem, and even when the control of the internal combustion engine is abnormal, for example, when the electronic throttle system fails, the output of the internal combustion engine can be improved based on the driver's request. It is an object of the present invention to provide a valve timing control device for an internal combustion engine that enables the vehicle to perform evacuation traveling performance.

[0005]

According to the valve timing control apparatus for an internal combustion engine of the present invention, control abnormality of the internal combustion engine is detected by the control abnormality detecting means. At this time, the output of the internal combustion engine is improved by the driver. Is required, the opening / closing timing or the lift amount of the variable valve timing control mechanism controlled in accordance with the operation state of the internal combustion engine by the valve control means is increased by the control amount correction means in the direction in which the output generated in the operation state increases. Is corrected to In other words, when the control of the internal combustion engine is abnormal, basically the control in the direction of decreasing the generated output is executed to be fail-safe, but at this time, if the output improvement by the driver is required, The variable valve timing control mechanism corrects the generated output in the operating state in a direction to increase. As a result, for example, even when the throttle valve is fixed in the vicinity of the fully closed state at the time of failure of the electronic throttle system, the output of the internal combustion engine can be improved, and the limp-home performance can be ensured.

In the valve timing control device for an internal combustion engine according to the second aspect, the variable valve timing control mechanism is controlled by the control amount correction means in a direction in which the output generated by the internal combustion engine increases, and the vehicle speed is increased. Restrictions are added so that the vehicle speed does not exceed the range of evacuation traveling. In this way, for example, in addition to ensuring the limp-home performance even when the electronic throttle system fails, for example, brake control and the like are executed and appropriately restricted so that the vehicle speed at that time does not become too high. An extremely practical and highly safe system can be constructed.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below based on examples.

FIG. 1 is a schematic configuration diagram showing a double overhead cam type internal combustion engine to which an internal combustion engine valve timing control device according to an embodiment of the present invention is applied, and peripheral devices thereof.

In FIG. 1, 1 is an internal combustion engine, 2 is a rotation angle θ of a crankshaft 31 as a drive shaft of the internal combustion engine 1.
1 A crank angle sensor for detecting a signal, 3 a water temperature sensor for detecting a cooling water temperature THW signal of the internal combustion engine 1, and 4 a rotation angle θ2 signal of a camshaft 33 as a driven shaft on the intake valve 32 side of the internal combustion engine 1. A cam angle sensor for calculating a relative rotation angle (displacement angle) from a phase difference from a rotation angle θ1 signal from the crank angle sensor 2; and 5, a throttle opening for detecting a throttle opening TA signal of the throttle valve 14. A sensor 6 is an intake air amount sensor such as an air flow meter that detects a QA signal of an intake air amount (intake air amount) to the internal combustion engine 1, and 7 is provided in the middle of an oil passage and has an oil temperature THO of hydraulic oil.
An oil temperature sensor that detects a signal, 8 is an accelerator opening sensor that detects an accelerator opening AP signal as an accelerator operation amount, and 9 is an oil-flow control valve (Oil-flow Control Valve) that adjusts and controls the oil pressure of hydraulic oil. OCV]),
Reference numeral 10 denotes the camshaft 3 with the hydraulic pressure adjusted by the OCV 9.
3 is a hydraulic variable valve timing control mechanism (Variable Valve Timming C) installed on the intake valve 32 side as an actuator that controls a target relative rotation angle (target displacement angle) which is a target phase difference with the crankshaft 31.
ontrol Mechanism: hereinafter referred to as "VVT"), 11 is an oil strainer for sucking hydraulic oil from the oil pan of the internal combustion engine 1, 12 is an oil pump for pumping hydraulic oil, and 13 is a throttle valve in an electronic throttle system. A DC motor 20 serving as an actuator for driving the internal combustion engine 1 detects an operating state of the internal combustion engine 1 based on input signals from various sensors, calculates an optimal control value, and
ECU (Elec) that outputs drive signals to the DC motor 9 and the DC motor 13
tronic Control Unit).

Next, the electrical configuration of the ECU 20 will be described with reference to FIG.

In FIG. 2, an ECU 20 includes a CPU 21 as a well-known central processing unit, a ROM 22 storing control programs, a RAM 23 storing various data, a cooling water temperature THW signal from the water temperature sensor 3, and a signal from the throttle opening sensor 5. Throttle opening degree TA signal, intake air amount sensor 6
QA signal from the oil temperature, oil temperature THO from the oil temperature sensor 7
Signal and accelerator opening AP from accelerator opening sensor 8
A / A that converts each analog signal into a digital signal
D conversion circuit 24, rotation angle θ1 from crank angle sensor 2
A waveform shaping circuit 25 for waveform shaping the signal and the rotation angle .theta.2 signal from the cam angle sensor 4.
A drive signal IDOCV based on the OCVDuty (duty ratio) control value DOCV, which will be described later, calculated in U21
9. Drive signal ITA based on output throttle opening TAEX
It is configured as a logical operation circuit including an output circuit 26 for outputting EX to the DC motor 13.

Next, a base routine of the CPU 21 in the ECU 20 used in the valve timing control apparatus for an internal combustion engine according to one embodiment of the present invention will be described with reference to a flowchart of FIG. This base routine is repeatedly executed by the CPU 21 at predetermined time intervals.

In FIG. 3, first, at the same time as the power is turned on (when the power is turned on), initialization is executed in step S100. In this initialization, the contents of the memory such as the RAM 23 are set to initial values, and input signals from various sensors are checked. After the initialization in step S100, the full-scale control process in the following loop is repeatedly executed.

In step S200, control abnormality detection processing for the internal combustion engine 1 is executed. Next, the process proceeds to step S300, and VV is set according to the detection result at step S200.
T target relative rotation angle calculation processing is executed. Next, the process proceeds to step S400, where V calculated in step S300 is used.
After the VVT relative rotation angle control processing based on the VT target relative rotation angle is executed, the process returns to step S200, and the same processing is repeatedly executed.

Next, each processing in the above-described base routine will be described in detail for each subroutine.

The details of the control abnormality detection processing routine of the internal combustion engine 1 in step S200 in FIG. 3 will be described with reference to the flowchart in FIG. In the present embodiment, as an example of a control abnormality of the internal combustion engine 1, a case where the electronic throttle system has failed will be described. This subroutine is repeatedly executed by the CPU 21 every 120 ms.

Referring to FIG. 4, first, at step S201, the accelerator opening AP [°] and the throttle opening TA [°] are read. Next, the routine proceeds to step S202, where the deviation between the accelerator opening AP and the throttle opening TA is determined by a predetermined value K1.
It is determined whether it is less than. If the determination condition of step S202 is not satisfied, that is, if the difference between the accelerator opening AP and the throttle opening TA is greater than or equal to a predetermined value K1, the process proceeds to step S203, where the throttle opening TA is set to a predetermined value K2 near full closure. It is determined whether it is less than. Step S2
When the determination condition of 03 is satisfied, that is, when the throttle opening TA is smaller than the predetermined value K2 near the fully closed state, step S2
The process proceeds to 04, where it is determined whether the accelerator opening AP exceeds a predetermined value K3.

If the condition of step S204 is satisfied, that is, if the throttle opening TA is close to fully closed despite the accelerator opening AP being larger than the predetermined value K3, the electronic throttle system is in a failure state. For example, the operation proceeds to step S205 assuming that the DC motor 13 has an operation failure or the like, and determines that the electronic throttle system is in a failure state, but the output improvement request flag FTA is determined that the driver is required to increase the output of the internal combustion engine 1. It is set to "ON (1)" and the routine ends. on the other hand,
When the determination condition of step S202 is satisfied, that is, when the deviation between the accelerator opening AP and the throttle opening TA is smaller than a predetermined value K1, or when the determination condition of step S203 is not satisfied, that is, when the throttle opening TA When the value is greater than or equal to the value K2, or when the determination condition of step S204 is not satisfied, that is, when the accelerator opening AP is less than the predetermined value K3, the output improvement request flag FTA is set to the initially set “OFF (0)”. This routine ends as it is.

In this embodiment, the variable valve timing control by the VVT 10 is performed only on the intake side.
As shown in FIG. 5, the advance / retard angle of the intake valve 32 is such that the opening / closing timing of the exhaust valve 34 is fixed with respect to TDC (Top Dead Center), and the opening / closing of the intake valve 32 is flexibly performed. The overlap amount is controlled by advancing / retarding the timing.

Next, V in step S300 in FIG.
For details of the VT target relative rotation angle calculation processing routine,
This will be described with reference to the flowchart of FIG. This subroutine is repeatedly executed by the CPU 21 every 16 ms.

In FIG. 6, in step S301, the engine speed NE [rpm], the intake air amount QA [g / sec], the accelerator opening AP [°], and the vehicle speed SPD [km / h] are read. Next, the process proceeds to step S302, and it is determined whether the output improvement request flag FTA set in FIG. 4 is “ON”. The determination condition of step S302 is satisfied,
That is, when the output improvement request flag FTA is "ON" and the driver is requesting the output enhancement, step S303.
And the engine speed N read in step S301.
A target relative rotation angle of VVT 10 is calculated from a map based on E, accelerator opening AP, and vehicle speed SPD. here,
From the map, for example, NE = ne1, AP = ap1, SPD =
In the case of spd1, a is calculated as the target relative rotation angle. The target relative rotation angle obtained from this map is an optimum value obtained in advance by calculation, experiment, or the like.

On the other hand, when the determination condition of step S302 is not satisfied, that is, when the output enhancement request flag FTA is "OFF" and the driver does not request the output enhancement, the process proceeds to step S304 and is read in step S301. VVT is obtained from the map based on the engine speed NE and the intake air amount QA.
Ten target relative rotation angles are calculated. Here, for example, when NE = ne1 and QA = qa1, a is calculated from the map as the target relative rotation angle. The target relative rotation angle obtained from this map is an optimum value obtained in advance by calculation, experiment, or the like. After the processing of step S303 or step S304, the process proceeds to step S305, where the calculated target relative rotation angle a is stored in “VTT” in the storage area of the target relative rotation angle in the RAM 23, and this routine ends. Therefore, in the following description, it is described as target relative rotation angle VTT.

Next, V in step S400 in FIG.
For details of the VT relative rotation angle control processing routine, see FIG.
This will be described with reference to the flowchart of FIG. This subroutine is repeatedly executed by the CPU 21 every 16 ms.

In FIG. 7, the target relative rotation angle VTT calculated in FIG. 6 and stored in the RAM 23 is read in step S401. Next, proceeding to step S402, the current relative rotation angle (also referred to as the actual relative rotation angle) VT of the VVT 10 based on the input signals from the crank angle sensor 2 and the cam angle sensor 4 is read. Next, the process proceeds to step S403, where the differential value DLVT is calculated from the difference between the previous relative rotation angle VT (i-1) and the current relative rotation angle VT (i). Next, the process proceeds to step S404, and a relative rotation angle deviation ERVT is calculated from the deviation between the current relative rotation angle VT (i) and the target relative rotation angle VTT.

Next, the routine proceeds to step S405, where a P (proportional) term correction value PVT is calculated from the table based on the relative rotation angle deviation ERVT calculated in step S404. Next, the process proceeds to step S406, and the process proceeds to step S40.
From the table based on the differential value DLVT calculated in step 3
A (differential) term correction value DVT is calculated. Note that the P-term correction value PVT calculated from the table in step S405 and the D-term correction value DVT calculated from the table in step S406 are optimal values obtained in advance through calculations and experiments. Next, the process proceeds to step S407, and step S4
05 and the P-term correction value PVT calculated in step S406
The D-term correction value DVT calculated in (1) and the previous OCVDuty control value DOCV are added to calculate the final OCVDuty control value DOCV, and this routine ends. This OC
VVT relative rotation angle control is performed by the VVT 10 via the OCV 9 from which the VDuty control value DOCV is output.
Here, in the operation of the OCV 9, as shown in the characteristic diagram of FIG. 8, the relative rotation angle control value [° CA] is increased by increasing the oil amount in proportion to the OCVD Uty control value DOCV [%]. .

Next, the operation of the present embodiment when the electronic throttle system fails will be described with reference to the time chart of FIG.

In FIG. 9, before time t 1,
Following the decrease in the accelerator opening AP [°], the throttle opening TA [°] transitions in the closing direction, and the accelerator opening A
The deviation between P and the throttle opening TA is smaller than a predetermined value (predetermined value K1 in FIG. 4), and the electronic throttle system is normal. In addition, the target relative rotation angle VTT [° C
A] changes to the retard side, and the vehicle speed SPD [km / h] changes to the low speed side.

Here, it is assumed that the electronic throttle system has failed at time t1. In this state, despite the fact that the accelerator opening AP has started to increase due to the driver's request to improve the output, the throttle opening TA has a predetermined value near the fully closed state (the predetermined value K2 in FIG. 4) due to the failure of the electronic throttle system. It is assumed that it is fixed to less than. Then, the accelerator opening AP is further increased by the driver's request for increasing the output,
At time t2, the deviation between the accelerator opening AP and the throttle opening TA exceeds a predetermined value (predetermined value K1 in FIG. 4), and the accelerator opening AP at this time exceeds a predetermined value (predetermined value K3 in FIG. 4). The output improvement request flag FTA changes from "OFF" to "ON". After this (time t2)
In the case of, the target relative rotation angle VTT [° CA] is shifted to the advanced side as shown by the solid line in FIG. As a result, the output of the internal combustion engine 1 is improved, the vehicle speed SPD [km / h] is increased, and the evacuation traveling performance can be secured.

Here, even after time t3, the accelerator opening AP is increased by the driver, but the vehicle speed S that achieves the limp-home performance when the electronic throttle system fails.
Since it is not preferable that PD [km / h] becomes too high, the vehicle speed is limited by a preset vehicle speed limit value α. That is, the target relative rotation angle VTT is fixed at time t3 when the vehicle speed SPD reaches the vehicle speed limit value α. But,
In this state, the vehicle speed SPD overshoots as indicated by the dashed line following the solid line in FIG. 9 as no brake control, so that the brake control is executed so that the vehicle speed SPD does not greatly exceed the vehicle speed limit value α. The vehicle speed limit value α is provided with a hysteresis.
As shown in FIG. 0, when the vehicle speed limit value α exceeds 70 [km / h], the brake control is turned “ON” and 60 [km / h].
h] is set to "OFF" when the following conditions are satisfied. As a result, the evacuation traveling performance can be satisfied without the vehicle speed SPD greatly exceeding the vehicle speed limit value α.

As shown by the broken line in FIG. 9 as no control, if the electronic throttle system fails, the control of the VVT 10 according to the present embodiment is not performed, and if the target relative rotation angle VTT remains fixed, the vehicle speed SPD is also fixed. It is impossible to perform evacuation traveling. Here, in order to execute the above-described brake control, it is necessary to provide a dedicated brake actuator (not shown) separately from the brake control by the normal brake operation. FIG.
As shown in FIG. 1, the vehicle speed limit value α [km / h] may be set according to the accelerator pedal opening AP [°].

Next, the brake control when the cause of the control abnormality disappears for some reason during the limp-home running due to the control of the VVT 10 according to the present embodiment when the control of the internal combustion engine 1 is abnormal and the internal combustion engine 1 returns to normal will be described with reference to the time chart of FIG. This will be described using a chart.

In FIG. 12, if it is assumed that the control abnormality of the internal combustion engine 1 has returned to normal at time t11, the throttle opening TA suddenly changes to the opening direction in an attempt to follow the accelerator opening AP at that time, and the internal combustion engine 1 The accelerator opening AP is immediately returned by the driver to blow up. Then, the above-described output improvement request flag that has been “ON” due to the control abnormality of the internal combustion engine 1 becomes “OFF” (time t1).
2). The target relative rotation angle VTT is also returned from the advance side to the retard side along with the output improvement request flag “OFF”. However, the movement of the VVT 10 is not so rapid, and if it is left as it is, the vehicle speed SPD once becomes too high as shown by the dashed line in FIG. 12 without brake control.
To cope with this, after the time t12 when the output improvement request flag changes from "ON" to "OFF", the brake control is executed as shown by the solid line in FIG. Is quickly matched with the vehicle speed SPD corresponding to the vehicle speed SPD.

As described above, the valve timing control device for an internal combustion engine according to the present embodiment transmits the driving force from the crankshaft 31 as the driving shaft of the internal combustion engine 1 to the camshaft 33 as the driven shaft for opening and closing the intake valve 32. The VVT 10 is provided in a driving force transmission system that changes the relative rotation angle VT of the camshaft 33 with respect to the crankshaft 31 for setting the opening / closing timing of the intake valve 32. The VVT 10 performs relative rotation by the VVT 10 according to the operating state of the internal combustion engine 1. Angle V
Valve control means achieved by the CPU 21 in the ECU 20 for controlling T, and E for detecting a control abnormality of the internal combustion engine 1.
A control abnormality detecting means achieved by the CPU 21 in the CU 20, and a control abnormality of the internal combustion engine 1 detected by the control abnormality detecting means. And a control amount correction means achieved by a CPU 21 in the ECU 20 for correcting the relative rotation angle VT controlled by the valve control means in a direction in which the generated output increases.

Accordingly, if a control abnormality of the internal combustion engine 1 is detected by the CPU 21 in the ECU 20 and the driver is requested to improve the output of the internal combustion engine 1 at this time,
The relative rotation angle VT of the VVT 10 controlled according to the operation state of the internal combustion engine 1 is corrected in a direction in which the output generated in the operation state increases. In other words, when the control of the internal combustion engine 1 is abnormal, the control in the direction of decreasing the generated output is basically performed and the fail-safe operation is performed.
The correction is made in a direction to increase the output generated in the operating state by the operation of the motor. As a result, for example, even when the throttle valve 14 is fixed in the vicinity of the fully closed state at the time of failure of the electronic throttle system, the output of the internal combustion engine 1 can be improved, and the limp-home performance can be ensured.

In the valve timing control device for an internal combustion engine according to the present embodiment, the control amount correction means achieved by the CPU 21 in the ECU 20 limits the increase in the vehicle speed SPD due to the increase in the output of the internal combustion engine 1. It includes limiting means. Therefore, the VVT 10 is controlled by the CPU 21 in the ECU 20 in the direction in which the generated output of the internal combustion engine 1 increases, and the vehicle speed SPD is increased. Is added. As a result, for example, in addition to ensuring the limp-home performance even when the electronic throttle system fails, for example, brake control or the like is executed and appropriately limited so that the vehicle speed SPD at that time does not become too high. Thus, a highly practical and highly safe system can be constructed.

In the above embodiment, the variable valve timing control mechanism is a VVT capable of changing the relative rotation angle VT of the camshaft 33 with respect to the crankshaft 31.
10 has been described, but the present invention is not limited to this, and the camshaft 33 may have a plurality of cams and the lift amount of the intake valve 32 may be changed according to the operating state of the internal combustion engine 1. It can also be applied to things that do.

Further, in the above-described embodiment, as an example of the control abnormality of the internal combustion engine 1, the case where the VVT 10 is controlled based on the detection of the failure of the electronic throttle system to improve the engine output has been described. However, the present invention is not limited to this. In addition, idle speed control (ISC: Idle Speed Control) for maintaining and controlling the engine speed during idle operation of the internal combustion engine 1 at a predetermined target speed.
The same control can be performed when a failure of the ISC valve, a failure of the ignition system of a specific cylinder of the internal combustion engine 1, a failure of the fuel system, or the like is detected.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram showing a double overhead cam type internal combustion engine to which a valve timing control device for an internal combustion engine according to one embodiment of the present invention is applied, and peripheral devices thereof.

FIG. 2 is an ECU in the valve timing control device for the internal combustion engine according to one embodiment of the embodiment of the present invention;
FIG. 2 is a block diagram showing an electrical configuration of the inside.

FIG. 3 is a flowchart showing a processing procedure of a base routine in a CPU in an ECU used in a valve timing control device for an internal combustion engine according to one embodiment of the present invention.

FIG. 4 is a flowchart illustrating a processing procedure for detecting a control abnormality of the internal combustion engine in FIG. 3;

FIG. 5 is an explanatory diagram showing advance / retard control of an intake valve in a valve timing control device for an internal combustion engine according to an example of an embodiment of the present invention.

FIG. 6 is a flowchart showing a processing procedure for calculating a VVT target relative rotation angle in FIG. 3;

FIG. 7 is a flowchart showing a processing procedure of VVT relative rotation angle control in FIG. 3;

FIG. 8 is an operation characteristic diagram of an OCV used in a valve timing control device for an internal combustion engine according to an example of the embodiment of the present invention.

FIG. 9 is a time chart showing an operation of the valve timing control device for an internal combustion engine according to one embodiment of the present invention when an electronic throttle system fails.

FIG. 10 is a characteristic diagram showing a relationship between a vehicle speed limit value and brake control in FIG.

FIG. 11 is a characteristic diagram showing a relationship between an accelerator opening and a vehicle speed limit value in FIG. 9;

FIG. 12 is a time chart showing an operation by the brake control when the internal combustion engine returns to normal from a control abnormality in the internal combustion engine valve timing control device according to one example of the embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 1 internal combustion engine 2 crank angle sensor 4 cam angle sensor 5 throttle opening sensor 8 accelerator opening sensor 9 OCV (hydraulic control valve) 10 VVT (variable valve timing control mechanism) 13 DC motor 14 throttle valve 20 ECU (electronic control unit) 31 Crankshaft (drive shaft) 33 Camshaft (driven shaft)

Claims (2)

[Claims] An opening / closing timing of the intake valve or the exhaust valve is provided in a driving force transmission system that transmits a driving force from a driving shaft of an internal combustion engine to a driven shaft that opens and closes at least one of an intake valve and an exhaust valve. Or a variable valve timing control mechanism capable of changing a lift amount, valve control means for controlling the opening / closing timing or the lift amount by the variable valve timing control mechanism in accordance with an operation state of the internal combustion engine, control of the internal combustion engine Control abnormality detection means for detecting abnormality; and when the control abnormality detection means detects a control abnormality of the internal combustion engine, when an output improvement of the internal combustion engine is required, the output generated in the operating state increases. A control amount for correcting the opening / closing timing or the lift amount controlled in the direction by the valve control means. A valve timing control device for an internal combustion engine, comprising: a correction unit. 2. The valve timing control for an internal combustion engine according to claim 1, wherein the control amount correction unit includes a vehicle speed limiting unit that limits an increase in a vehicle speed due to an increase in the output of the internal combustion engine. apparatus.