JP3018819B2 - Output control device for internal combustion engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an output control device for an internal combustion engine which electrically controls a throttle opening and variably controls at least one timing of intake and exhaust valves.

[0002]

2. Description of the Related Art A conventional output control device for an internal combustion engine is disclosed in, for example, Japanese Patent Application Laid-Open No. 1-80733, in which a driver's accelerator is operated in accordance with switching of intake and exhaust valves of the internal combustion engine. The ratio of the throttle opening to the input is varied using an electronically controlled throttle device, and the internal combustion engine is operated utilizing the characteristics of the respective intake and exhaust valve timings.

[0003]

In the above-mentioned conventional output control device for an internal combustion engine, an electrically controlled throttle device fails for some reason, and an accelerator opening-throttle opening characteristic according to each valve timing. If the throttle opening cannot be obtained, the accelerator opening-throttle opening characteristic becomes a single characteristic, so that different output torques are generated at the same throttle opening, especially at both valve timings to be switched at the time of switching the valve timing. In such a case, there is a problem that a shock occurs when switching the valve timing.

[0004] The present invention has been made in view of the above,
An object of the present invention is to provide an output control device for an internal combustion engine that does not cause a valve timing switching shock even when a throttle control device fails.

[0005]

In order to achieve the above object, an output control device for an internal combustion engine according to the present invention comprises a throttle electronic control device for controlling a throttle opening to an arbitrary value based on an accelerator depression amount, and an intake and exhaust valve. in an internal combustion engine having a variable valve mechanism for switching the operating conditions of the timing or lift, a failure detecting means for detecting a failure of the electronic throttle control device, to the fault detection means
When a failure of the throttle electronic control unit is detected,
Slot for accelerator opening corresponding to valve timing
Among the characteristics of the throttle opening, the accelerator opening that can be realized-
Feasible accelerator-slot to determine the characteristics of the rottle opening
Means for determining the characteristic of the throttle opening degree, and the accelerator-slot
Accelerator-throttle opening by means of the throttle opening characteristic judgment means
When it is determined that the degree characteristics cannot be realized, the accelerator opening
Accelerator opening that fixes the ratio of the throttle opening to the throttle
A throttle opening ratio fixing means, and a valve timing switching operating point changing means for changing a switching operating point of the intake / exhaust valve timing when a failure of the throttle electronic control unit is detected by the failure detecting means; The gist of the invention is to have valve timing switching means for switching the valve timing at the switching operation point.

[0006]

In the output control device for an internal combustion engine according to the present invention, when a failure of the electronic throttle control device is detected, each valve
Throttle opening for accelerator opening corresponding to imming
Accelerator opening-throttle that can be achieved
Judging the characteristics of the opening, the accelerator-throttle opening characteristics
When it is determined that it cannot be realized,
While fixing the throttle opening ratio,
For example, when the operating point for
Degree-change to the equal output point, and this changed switching operating point
Use to switch the valve timing. This allows the slot
Some cam profiles due to a partial failure of the electronic control unit
Accelerator-throttle opening characteristics for
If the failure mode is
Cam profile corresponding to cell opening-throttle opening characteristics
In addition to being able to perform degenerate operation making full use of files,
・ Improves drivability by preventing torque fluctuation during profile switching
Can be improved.

[0007]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing a configuration of an output control device for an internal combustion engine according to an embodiment of the present invention. The output control device of the internal combustion engine shown in FIG. 1 includes a throttle control device failure detecting means 1 for detecting a failure of the throttle electronic control device, and a failure of the throttle electronic control device detected by the throttle control device failure detecting device 1. An accelerator opening-throttle opening ratio fixing means 3 for fixing the ratio of the throttle opening to the accelerator opening, and an intake / exhaust valve when the throttle control failure detection means 1 detects a failure of the throttle electronic control unit. Valve timing switching operating point changing means 5 for changing a timing switching operating point; and valve timing switching operating point changing means 5
Valve timing switching means 7 for switching the valve timing at the switching operation point changed by the above.

FIG. 2 is a diagram showing a configuration of a system to which the output control device of the internal combustion engine shown in FIG. 1 is applied. In FIG. 2, reference numeral 58 denotes a cam position sensor which detects a current intake / exhaust valve timing CPn of the engine. 5
Reference numeral 4 denotes a throttle opening sensor which detects an opening TH of a throttle 57 driven by a servomotor 56.
An accelerator operation amount sensor 53 detects the accelerator operation amount α of the driver. 52 is a crank angle sensor,
The engine crank angle CA is detected.

Each signal detected by the crank angle sensor 52, the accelerator operation amount sensor 53, the throttle opening sensor 54 and the cam position sensor 58 is input to the CPU 51. The CPU 51 calculates a target cam profile for optimizing the operating state of the engine based on these signals, and controls a valve timing switching hydraulic pressure to realize the target cam profile. Timing switching solenoid valves 45, 46
To the desired cam and
Realize the profile.

Further, the CPU 51 determines the characteristics of the throttle opening degree with respect to the accelerator operation by the driver by setting the characteristic of the set cam / torque.
Calculate to be appropriate for the profile,
A signal is sent to a servo drive circuit 55 for controlling the throttle opening, and the servo motor 56 is controlled to realize a desired throttle opening THm.

Next, the operation will be described with reference to the flowchart shown in FIG.

The flowchart shown in FIG.
1 shows the control operation, but this control operation is, for example, 4 control operations.
It is executed every predetermined cycle such as msec.

In FIG. 3, first, a target throttle opening THm calculated by the CPU 51 and supplied to the servo drive circuit 55 is read (step P1). Next, the actual throttle opening TH controlled by the servo motor 56 driven by a signal from the servo drive circuit 55 is read (step P2).

The target throttle opening THm read in steps P1 and P2 is compared with the actual throttle opening TH actually driven and controlled, and the absolute value | THm−TH | of the difference between the two is set to a predetermined value e _TH. It is checked whether it is greater than (step P3). Absolute value of difference | THm−
If TH | is larger than the predetermined value e _TH , it is determined that the throttle opening control device has failed due to some abnormality, and the process proceeds to step P4 and the subsequent steps. Is determined not to exist, and the process exits to continue the current control.

In step P4, when it is determined in step P3 that a malfunction has occurred in the throttle opening control device, the ratio of the accelerator pedal depression amount α of the driver to the target throttle opening THm is determined. _RTA is fixed to a predetermined value _Rem at all valve timings. The predetermined value R _em, for example the structure as an accelerator depression amount of the driver α is mechanically transmitted to the throttle with the transmission ratio R _em by operating a clutch provided in the control drive section of the throttle It is realized by doing.

In the next step P5, the valve timing switching operating point map _Mcp , which has been used so far, is switched to a map _Mem in which switching is performed at an equal throttle opening-equal output point. Thereafter, the valve timing switching control is performed based on the switching operating point map M _em, and appropriate signals are supplied to the respective solenoid valves 45 and 46 for switching valve timing.

In one embodiment of the present invention described above, in order to obtain an optimum combustion state at various operating points, an internal combustion engine having a cam profile configuration capable of realizing several valve timings and a switching device therefor is provided. In the engine, for example, when one cam profile is used to the extent that its characteristics can be fully utilized and when switching to the next cam profile, switching with the same throttle opening is realized with both cam profiles There is a large difference in engine output, and if switching is performed as it is, a switching shock due to this engine output difference occurs, impairing drivability, and the engine output generated by both cam profiles at the same switching is the same. Control the throttle opening so that
It is conceivable to prevent this switching shock from occurring and to make full use of the characteristics of each cam profile.

However, if a failure occurs in the throttle opening control system and a desired throttle opening cannot be obtained, the characteristics of each cam profile cannot be utilized, and a switching shock occurs when the cam profile is switched. However, it is inevitable that driving performance deteriorates.

Therefore, in the event of such a failure in the throttle opening control system, the characteristics of the throttle opening with respect to the accelerator opening are constant at all operating points and can cover the entire region as much as possible. By switching the cam profile at an operating point that generates equal output at the same throttle opening instead of the conventional switching operating point, the occurrence of a shock accompanying the switching of the cam profile can be prevented, Also, multiple cam profiles can be used.

For example, as shown in FIG.
In an internal combustion engine in which two cam profiles can be realized, the first cam profile is such that fuel efficiency is emphasized. In normal use, the first cam profile is used until almost full open, and switching is performed. If it is used to switch to the next second cam profile when it comes to the point A, when the throttle control system breaks down,
Since the throttle opening is almost fully opened, the operating point shifts to B at the moment when the cam profile is switched, and a considerable output difference occurs. However, when the use area of the fuel efficiency-oriented cam profile is slightly narrowed, there is an operating point at which the equal throttle opening-equal output can be realized at a location indicated by a dotted line. Therefore, if the cam profile is switched at this point, even when the accelerator opening-throttle opening characteristic cannot be switched due to a single characteristic, the shock at the time of switching the cam profile is eliminated and the drivability is improved. And
Almost the characteristics of each cam profile can be used.

FIG. 4 is a block diagram showing a configuration of an output control device for an internal combustion engine according to another embodiment of the present invention.

In the embodiment shown in FIG. 4, a throttle control device failure detecting means 1 for detecting a failure of the throttle electronic control device, and when a failure of the throttle electronic control device is detected by the throttle control device failure detecting device 1, Among the characteristics of the throttle opening with respect to the accelerator opening corresponding to each valve timing, a feasible accelerator-throttle opening characteristic determining means 9 for determining a realizable accelerator opening-throttle opening characteristic; when failure of the electronic throttle control device is detected by the detection means 1, the valve timing changeover operation point changing means 5 for changing the switching operation point of the intake and exhaust valve timing was changed by the valve timing changeover operation point changing means 5 the valve timing switching for switching the valve timing by switching the operating point Means 7 and an accelerator opening-throttle opening ratio fixing means 3 for fixing the ratio of the throttle opening to the accelerator opening when the accelerator-throttle opening characteristic cannot be realized, and are realized in the embodiment of FIG. The difference is that a possible accelerator-throttle opening characteristic determining means 9 is added.

The system configuration to which the output control device for an internal combustion engine of the embodiment shown in FIG. 4 is applied is the same as that shown in FIG.

Next, the operation will be described with reference to the flowchart shown in FIG. The flowchart shown in FIG.
Although the control operation of U51 is shown, this control operation is executed at predetermined intervals, for example, 4 msec.

In the processing shown in FIG. 5, steps P1 to P3 are the same as the processing shown in FIG. 3, and the target throttle opening T calculated by the CPU 51 and supplied to the servo drive circuit 55.
Hm is read, and the actual throttle opening TH controlled by the servomotor 56 actually driven by a signal from the servo drive circuit 55 is read. Then, the read target throttle opening THm and the actually driven and controlled actual throttle opening TH are compared, and whether or not the absolute value | THm−TH | of the difference between them is greater than a predetermined value e _TH Is checked.

If the absolute value of the difference | THm−TH | is larger than the predetermined value e _TH , it is determined that some abnormality has occurred in the throttle opening control device and the throttle opening control device has failed. The driver's accelerator depression amount α is read. It is determined whether or not the read accelerator depression amount α is larger than the maximum accelerator depression amount α1 in the accelerator-throttle opening degree characteristic for the first cam profile (step P7).
It is determined that the accelerator-throttle opening characteristic for at least the first cam profile can be realized, and the process proceeds to Step P9. If the accelerator-throttle opening characteristic for the first cam profile is not sufficient, the accelerator-throttle opening characteristic cannot be sufficiently realized. And the process proceeds to Step P8.

In step P8, a discrimination flag F1 for controlling the throttle opening is set to 1. Then, the accelerator depression amount α of the driver and the target throttle opening TH
also fixed to a predetermined value R _em in all valve timing ratio R _TA of m (step P4). The predetermined value R _em, for example the structure as an accelerator depression amount of the driver α is mechanically transmitted to the throttle with the transmission ratio R _em by operating a clutch provided in the control drive section of the throttle It is realized by doing.

In the next step P5, the valve timing switching operating point map _Mcp , which has been used so far, is switched to a map _Mem in which switching is performed at an equal throttle opening-equal output point. Thereafter, the valve timing switching control is performed based on the switching operating point map M _em, and appropriate signals are supplied to the respective solenoid valves 45 and 56 for switching valve timing.

In step P9, when it is determined in step P7 that the accelerator-throttle opening degree characteristic for the first cam profile can be realized, the accelerator depression amount α is set to the maximum accelerator depression amount for the second cam profile. It is determined whether it is larger than α2, and if it is larger, it is determined that the accelerator-throttle opening degree characteristic can be realized even for the second cam profile, and the process proceeds to Step P12. It is determined that the accelerator-throttle opening degree characteristic for the second cam profile cannot be realized, and the program proceeds to Step P10.

In step P10, the discrimination flag F2 for controlling the throttle opening is set to 1, and the map of the valve timing switching operation point is set to the second cam / point.
Only at the time of switching between the profile and the third cam profile, the map is switched to the map _Mem1 which becomes the equal throttle opening-equal output point (step P11).

In step P12, when it is determined in step P9 that at least the accelerator-throttle opening characteristic for the second cam profile can be realized, the determination flag F3 for throttle opening control is set to 1. .

Next, the control operation of the CPU 51 during the throttle opening control will be described with reference to the flowchart shown in FIG. The processing shown in FIG.
It is executed at every predetermined cycle such as c.

In FIG. 6, in step Q1, it is determined whether or not the present time is the switching timing of the valve timing based on the output signal from the valve timing switching determining process. If it is not the switching timing, the present process is terminated. If there is, it is determined whether or not the current throttle opening control flag F1 is 1 (step Q).
2). If the flag is not 1, the process is terminated. If the flag is 1, it is determined whether or not this switching is to switch from which cam profile to which cam profile. In the case of switching from the profile to the second cam profile, step Q
4 to move from the second cam profile to the first cam profile.
In the case of switching to the profile, the process proceeds to step Q8, and in the case of the second cam profile to the third cam profile, the process proceeds to step Q10, where the third cam profile is switched to the second cam profile. In the case of switching to, the process proceeds to step Q13.

In step Q4, the target throttle opening TH _m1 after the switching is calculated, and it is determined whether or not the actual throttle opening TH matches the target throttle opening TH _m1 (step Q5). Step Q until they match
When the throttle opening is obtained for the second cam profile, it is determined whether or not the throttle opening control flag F2 is 1 (step Q6). If not 1, but the process is terminated, in the case of 1, the following accelerator - to secure the throttle opening degree characteristic R _TA to a predetermined value R _em1 (step Q7), and the process ends.

In step Q8, the target throttle opening THm2 after the change is calculated, and the subsequent throttle opening _THm2 is calculated.
The throttle opening characteristic _{RTA is changed} to the normal characteristic R _N1 for the first cam profile (step Q9), and the process ends.

Furthermore, in step Q10, it calculates a target throttle opening degree TH _m3 after switched, it is determined whether the target throttle opening degree TH _m3 matches the actual throttle opening TH (step Q11). Wait at step Q11 until they match, and when they match,
Secure the throttle opening degree characteristic R _TA to a predetermined value R _em (step Q12), the process ends.

[0038] In step Q13, calculates a target throttle opening degree TH _m4 after switched, since the accelerator - to change the fixed throttle opening degree characteristic R _TA to the characteristic R _N2 for normal second cam profile ( Step Q14), this process ends.

In the other embodiment of the present invention described above, if the value of the accelerator depression amount α of the driver used for controlling the accelerator-throttle opening degree does not indicate, for some reason, for example, a value equal to or greater than a certain depression amount. Therefore, the throttle opening means cannot perform control beyond a certain throttle opening, and the operating range of the engine becomes very small.In such a case, conventionally, for example, the entire region of the accelerator and the throttle opening are mechanically linked. However, when the cam profile is changed, as described in the first embodiment, the cam profile is changed.
Because an output difference occurs when switching profiles,
The cam profile is switched at the equal throttle opening-equal output point. However, if the throttle opening can be controlled up to a certain amount of accelerator depression,
For example, if the output value of the accelerator sensor does not show a certain value or more due to a change in the ground level or the like, but the output value is such that the accelerator-throttle opening degree characteristic with respect to the first cam profile can be realized, the characteristics of this cam profile For example, it is possible to perform driving with an emphasis on fuel efficiency.
When the first and second cam profile operation regions can be realized, it is possible to realize various operation patterns such as the above-mentioned operation such as emphasis on fuel efficiency and the emphasis on acceleration performance by early switching.

Therefore, when the accelerator-throttle opening degree characteristic in the operation region of at least one cam profile can be realized, it is necessary to operate the cam profile sufficiently.

[0041]

As described above, according to the present invention,
When only a single accelerator opening-throttle opening characteristic is obtained due to a failure of the throttle electronic control device, an operating point for switching a plurality of valve timings becomes an equal output at an equal throttle opening before and after the valve timing before and after the switching. By adopting such a point, even when the throttle electronic control device fails, no switching shock of the switching timing of the valve timing occurs, and the entire operation range can be used.

[Brief description of the drawings]

FIG. 1 is a block diagram showing a configuration of an output control device for an internal combustion engine according to one embodiment of the present invention.

FIG. 2 is a diagram showing a configuration of a system to which the output control device of the internal combustion engine shown in FIG. 1 is applied.

FIG. 3 is a flowchart showing the operation of the embodiment shown in FIG. 1;

FIG. 4 is a block diagram showing a configuration of an output control device for an internal combustion engine according to another embodiment of the present invention.

FIG. 5 is a flowchart showing the operation of the embodiment shown in FIG.

FIG. 6 is a flowchart showing a control operation of a CPU at the time of throttle opening control in the embodiment shown in FIG. 4;

FIG. 7 is a diagram showing output characteristics of the internal combustion engine.

FIG. 8 is a diagram showing accelerator opening-throttle opening characteristics.

[Explanation of symbols]

 1 Throttle control device failure detecting means 3 Accelerator opening-throttle opening ratio fixing means 5 Valve timing switching operating point changing means 7 Valve timing switching means 9 Feasible accelerator-throttle opening degree characteristic judging means

──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Hideo Nakamura 2 Takaracho, Kanagawa-ku, Yokohama-shi, Kanagawa Nissan Motor Co., Ltd. (56) References JP-A-4-91331 (JP, A) JP-A-2- 91432 (JP, A) JP-A-64-80733 (JP, A) JP-A-4-292551 (JP, A) JP-A-4-134160 (JP, A) JP-A-4-103840 (JP, A) JP-A-4-365949 (JP, A) JP-A-4-269353 (JP, A) JP-A-5-79363 (JP, A) JP-A-4-269313 (JP, A) JP-A-5-59998 (JP, A) JP-A-5-125966 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) F02D 41/22 310 F02D 41/22 320 F01L 13/00 301 F02D 9 / 02 341 F02D 13/02

Claims (1)

(57) [Claims] 1. An internal combustion engine comprising: a throttle electronic control device for controlling a throttle opening to an arbitrary value from an accelerator depression amount; and a variable valve mechanism for switching a timing or a lift amount of an intake / exhaust valve according to operating conditions. Failure detection means for detecting a failure of the control device; and a failure of the throttle electronic control device by the failure detection means.
When detected, the access corresponding to each valve timing
Of the throttle opening characteristics with respect to the throttle opening
To determine the characteristics of accelerator opening-throttle opening
A possible accelerator-throttle opening degree characteristic determining means and a feasible accelerator-throttle opening degree characteristic determining means
Accelerator-throttle opening characteristics cannot be realized
Of throttle opening to accelerator opening
Accelerator opening-throttle opening ratio fixing means for fixing the combination
If, when a failure of the electronic throttle control device is detected by said fault detecting means, and the valve timing switching operating point changing means for changing the switching operation point of the intake and exhaust valve timing, a valve timing switching operating point which is the change An output control device for an internal combustion engine, comprising: valve timing switching means for switching.