JPH0559999A - Engine output control device - Google Patents

Abstract

(57) [Summary] [Purpose] Actually measure the response delay time until switching of the cam, and according to the deviation between this value and the preset value, the output correction is synchronized with the actual switching of the cam. By changing the output correction timing, the adverse effects of defective operation due to deterioration of hydraulic oil are eliminated. [Structure] The setting means 79 presets a basic response delay time from the output of the cam switching signal to the cam switching according to the sensor detection value. If the actual response delay time is longer than the basic response delay time according to the difference between the actual response delay time measured by the measuring means 80 and the basic response delay time, the timing advancing / retarding means 81 causes the engine for absorbing the torque step when switching the cam. If the output correction timing is delayed, and conversely, if it is shorter than the basic response delay time, the engine output correction timing is advanced.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an engine output control device having a variable valve mechanism for switching cams depending on operating conditions.

[0002]

2. Description of the Related Art A valve operating system for driving intake and exhaust valves of an engine is set so as to obtain optimum valve timing in accordance with output characteristics required by the engine.

However, the required valve timing differs depending on the operating conditions of the engine. For example, the valve lift and the valve opening period are both small in the low load region, whereas the large valve lift and the valve opening period are required in the high load region. To be done. For an engine having a wide range of operating conditions, such as an automobile engine, it is difficult to determine which operating region the valve timing is intended for, and in any case, optimum matching cannot be achieved under all operating conditions.

Therefore, as disclosed in Japanese Unexamined Patent Publication No. 63-167016, a plurality of cams having different cam characteristics (cam profiles) are provided, and the cams are switched according to the operating conditions, so that the optimum valve for each of them is obtained. A variable valve operating device that can be operated at a timing has been proposed.

This is to switch between a low speed type cam having a high torque in a low speed range and a high speed type cam having a high torque characteristic in a high speed range depending on the operating conditions, and to achieve a high output from a low speed range to a high speed range. It is the one that tries to make it. In addition to this, it has also been proposed to provide a fuel consumption cam having excellent fuel consumption characteristics in the partial load range to improve the fuel consumption in the partial load range.

[0006]

By the way, in the above-mentioned cam switching, the number of revolutions at which the outputs match at the same throttle opening is selected so that the engine output does not change discontinuously before and after the switching. However, as the selected cams, two cams having characteristics that emphasize output (torque) in a low rotation range and a high rotation range and a fuel consumption cam that emphasizes fuel economy in the partial load range are selected. When equipped with two cams, when switching from the fuel economy cam to the output cam (or vice versa), since the torque generated by the fuel economy cam is relatively low, the same throttle opening is used before and after the switch. If you try to maintain it, the torque step will become very large.

That is, the transition from the low speed type output cam to the high speed type output cam may be made by switching the rotational speeds at which the same output is obtained as described above, but in the case of the fuel consumption cam, the throttle opening is changed. Since the output torques are the same and the output torques do not match, a large torque step occurs at the time of switching.

Then, switching from the fuel consumption cam to the output cam is
In the low speed range, the low speed type output cam is used, and in the high speed range, the high speed type output cam is used.However, of course, in the low speed range, the low speed type output cam produces a larger torque than the high speed type output cam. The same is true in the range, so that a large torque step is generated regardless of which rotation range is changed.

The switching of the cams is performed according to the driver's intention, that is, the opening degree of the accelerator pedal. For example, the accelerator pedal is further depressed during the operation with the fuel consumption cam to exceed the range of the fuel consumption cam. When a high output torque is required, either the low speed type or the high speed type output cam is selected and switched from the rotation range at that time.

Therefore, in order to absorb a large torque step generated before and after such switching, the throttle valve is separated from the accelerator pedal so that the opening degree can be controlled independently. The outputs are matched by automatically correcting the throttle opening degree, the ignition timing, etc. as much as necessary to absorb the torque difference determined from the rotation speed and the like. For example, when shifting from the fuel consumption cam to the output cam, the output torque rapidly increases with the throttle opening unchanged, so the opening of the throttle valve is decreased and the ignition timing is temporarily retarded.

By the way, since the switching of the cams is performed by selectively connecting the rocker arms that respond to the respective cams using hydraulic pressure, the actual switching of the cams to the solenoid valve for hydraulic pressure switching, etc. There is a response delay before the cam is switched to.

This response delay is greatly influenced by the oil temperature and hydraulic pressure of the hydraulic oil. Therefore, if the response delay time is set in accordance with these, the above output correction can be performed in accordance with the switching of the cam. You can

However, if the hydraulic oil deteriorates due to long-term use and the hydraulic system malfunctions, the output correction timing will not match the actual cam switching, and the torque step during cam switching must be absorbed. Can not be.
For example, when switching from a fuel economy-oriented cam with a large torque step to an output cam, if the cam is switched with a great delay from the planned cam switching timing, the throttle opening up to that point is necessary. Since the throttle opening is rapidly reduced and the ignition timing is significantly retarded, combustion becomes unstable and misfire may occur.

Therefore, according to the present invention, the response delay time until the switching of the cam is actually measured, and the output correction is synchronized with the actual switching of the cam according to the deviation between this value and the preset value. By changing the timing of output correction, the purpose is to eliminate the adverse effects of defective operation due to deterioration of hydraulic oil.

[0015]

As shown in FIG. 1, a first aspect of the present invention is directed to a plurality of cams 71 having cam profiles having different output characteristics, and selectively operating these cams 71 by operating a hydraulic switching valve. A cam switching mechanism 72 for switching and transmitting the motion of the cam 71 to at least one of the intake and exhaust valves.
A sensor 73 for detecting an operating condition, and means 74 for determining whether to switch the cam according to the operating condition,
When the cam switching is determined from the determination result, the means 75 for outputting a cam switching signal to the hydraulic pressure switching valve of the cam switching mechanism 72 and the engine output so that the torque generated before and after the switching when the cam is switched are the same. In the engine including the means 76 for correcting the above, the sensors 77, 78 for detecting the temperature T and the pressure P of the hydraulic oil supplied to the hydraulic pressure switching valve.
And a means 79 for presetting a basic response delay time from the output of the cam switching signal to the cam switching according to these detected values, and an actual response delay time t from the output of the cam switching signal to the cam switching. When the actual response delay time is longer than the basic response delay time according to the difference between the actual response delay time and the basic response delay time, the output correction timing is delayed, and vice versa. And means 81 for accelerating the timing of the output correction.

The second invention, as shown in FIG. 2, includes a plurality of cams 71 having cam profiles having different output characteristics,
A cam switching mechanism 72 for selectively switching these cams 71 by the operation of the hydraulic pressure switching valve and transmitting the motion of the cam 71 to at least one of the intake and exhaust valves, a sensor 73 for detecting the operating condition, and the operating condition Accordingly, a means 74 for determining whether to switch the cam, a means 75 for outputting a cam switching signal to the hydraulic pressure switching valve of the cam switching mechanism 72 when the cam switching is determined from the result of the determination, and the switching of the cam In an engine equipped with a means 76 for correcting the engine output so that the torques generated before and after the switching are sometimes the same, the temperature T of the hydraulic oil supplied to the hydraulic switching valve is increased.
And sensors 77 and 78 for detecting the pressure P, means 79 for presetting a basic response delay time from the output of the cam switching signal to the cam switching according to the detected values, and the cam from the output of the cam switching signal. Means 80 for measuring the actual response delay time t until switching, and a response correction amount which becomes larger when the actual response delay time is longer than the basic response delay time in accordance with the difference between the actual response delay time and the basic response delay time. , A means 92 for generating a determination index δ associated with the index, a means 93 for comparing the determination index δ with the response correction amount, and a value larger than the previous index m by 1 from the comparison result. If the response correction amount is larger than the judgment index δm + 1 accompanying the index m + 1, the previous control waiting cycle number C and the previous index m are increased by one, and the response correction is made from the judgment index δm accompanying the previous index m. One small control wait cycle number C and the previous index m and the previous small, the response correction amount determination index δm above, accompanied the previous index m and the 1
If it is smaller than the determination index δm + 1 accompanied by the index m + 1 that is larger than the index m + 1, a means 94 for maintaining the previous control waiting cycle number C and the previous index m, and the updated control waiting cycle number C and index m are stored. Means 95 and means 96 for determining the timing of the output correction according to the updated control waiting cycle number C are provided.

[0017]

In order to absorb the torque difference during the cam switching, it is necessary to correct the output in accordance with the actual cam switching.

When the cam is switched by the operation of the hydraulic switching valve, the response delay time from the output of the switching signal to the switching valve until the actual switching of the cam is the oil temperature of the hydraulic oil supplied to the hydraulic switching valve. Since it is determined according to the hydraulic pressure, this makes it possible to execute the output correction according to the actual cam switching.

However, due to deterioration of hydraulic oil due to long-term use, malfunction of the switching valve etc. occurs,
The actual response delay time may deviate from the set value.

At this time, in the first aspect of the invention, the actual response delay time t is measured, and if the actual response delay time is longer than the set value, the output correction timing is delayed. On the contrary, if it is shorter than the set value, the timing of output correction is advanced. That is, the output correction timing is changed in accordance with the actual cam switching, and the actual cam switching and the output correction timing are synchronized again.

Also in the second invention, the control waiting cycle number C is determined in accordance with the actual cam switching, and this cycle number C
Since the timing of output correction is changed according to
Actual cam switching and output correction timing are synchronized.

On the other hand, the response correction amount and the judgment index δ are compared in order to check the difference between the actual response delay time and the set value. At this time, the judgment index m accompanying the judgment index is the comparison result. When it is updated in accordance with the above, the determination index used for the comparison with the response correction amount this time is 1 from the determination index δm accompanying the determination index m in the previous processing and the determination index m in the previous processing.
Only the judgment index δm + 1 accompanied by the judgment index m + 1 which is as large as two.

[0023]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS First, FIGS. 3 and 4 show a concrete structure of a variable valve operating device of an embodiment, which has already been proposed by the present applicant as Japanese Patent Application No. 2-117261. ..

Numeral 21 is set to a fuel consumption-oriented cam profile, and the first cam lift and the lift section are both small.
A cam (fuel consumption cam), 22 is set to a cam profile that generates a high torque in a low rotation range, a second cam (low speed type output cam) having a relatively larger cam lift than the first cam 21, and 23 is a high rotation. It is a third cam (high speed type output cam) which is set to a cam profile which generates a high torque in a range and has a cam lift and a lift section larger than the second cam 22, and these are provided in parallel on the same cam shaft.

Reference numeral 24 is an intake / exhaust valve (intake valve or exhaust valve), and 25 is a main rocker arm which is in constant contact with the first cam 21 via a roller 26. The main rocker arm swings around a rocker shaft 27 to serve as an intake. -Open and close the exhaust valve 24.

The main rocker arm 25 has a shaft 3
Two sub-rocker arms that swing about 0 as a fulcrum
8, 29 are supported in parallel with the roller 26, one sub rocker arm 28 contacts the second cam 22, and the other sub rocker arm 29 contacts the third cam 23.

When the sub rocker arms 28 and 29 are not engaged with the main rocker arm 25, they are constantly urged by the lost motion spring 31 so as to come into contact with the second and third cams 22 and 23, and the main rocker arms 28 and 29 are in contact with each other. It moves (swings) independently of the arm 25.

In order to selectively engage the sub rocker arms 28 and 29 with the main rocker arm 25, first, a columnar pin 32 is provided at the swinging portion of one of the sub rocker arms 28, and then the main rocker arm. Pins 34 are also provided on the shaft 25 so as to be coaxial with the pins 32 so as to be slidable in the camshaft direction.
2, 34 are normally urged by the return spring 36 to be held in the state of FIG. 3 and disengaged from the main rocker arm 25, but the hydraulic chamber 3 in which the pin 34 is housed
When the pressure oil is introduced into the passage 8 through the passage 40, the pins 32 and 3
4 is pushed out by a predetermined amount, and the sub rocker arm 28
Engages with the main rocker arm 25.

The sub rocker arm 28 and the main rocker arm 25 are integrated with each other by the first cam 21 and the second rocker arm 25.
When the cam 22 is in the base circle, the
The valve timing is switched according to the second cam 22 having a larger lift than the cam 21.

That is, the characteristic of the first cam 21 that emphasizes fuel consumption is switched to the characteristic of the second cam 22 that emphasizes output in the low rotation range.

The other sub-rocker arm 29 is also constructed in the same manner, and when pressure oil is introduced into the hydraulic chamber 39 through the passage 41, the pins 35 and 33 are pushed out against the return spring 37, Sub rocker arm 2
By engaging 9 with the main rocker arm 25,
The valve timing is switched so as to depend on the third cam 23, which has a larger lift and a larger lift section than the first cam 21 as described above, and output-oriented characteristics in a high rotation range can be obtained.

In FIG. 5, the first cam 21 to the third cam 2
The valve lift characteristics up to 3 are shown. The full-open output characteristics when each cam is used are as shown in FIG. 6. According to the first cam, the generated torque is low but the fuel consumption is good, and the second
The cam has the highest maximum torque in the low rotation range, and the third cam 23 has a smaller generated torque in the low rotation range than the second cam 22, but has the highest maximum torque in the high rotation range.

By the way, switching from the first cam 21 to the second and third cams 22 and 23, and vice versa, the second and third cams 2
A control unit 51 as shown in FIG. 7 is provided for controlling the switching from the second cam 23 to the first cam 21.
The optimum cam is selected according to the driving condition.

The selection of this cam in the control unit 51 is based on the characteristics shown in FIG. 6, and when the required torque and rotational speed are within the range of the first cam 21, which is a fuel consumption cam, for example, this fuel consumption cam is used and this state is selected. When the accelerator opening increases and the required torque deviates from the fuel consumption cam region to the region of the second cam 22 which is, for example, a low speed type output cam, the fuel consumption cam is switched to the low speed type output cam and the rotation speed is changed. Is rising from low rpm to high rpm,
It is switched to the third cam 23 which is a high speed type output cam.

Therefore, in the control unit 51, the engine speed N, the crank angle sensor 52 for detecting the crank angle position, the accelerator operation amount sensor 53 for detecting the operation amount (depression amount) of the accelerator pedal, and actually selected. When the signal from the cam position sensor 58 for detecting the cam position is input and the switching of the cam is determined based on these signals, the solenoid valve 45 for switching the hydraulic pressure to the two hydraulic chambers 38, 39 is described. And control the operation of 46.

That is, when one solenoid valve 45 is opened, the pressure oil from the oil pump is introduced into the hydraulic chamber 38 in order to operate the second cam 22, and the other solenoid valve 46 is opened. The pressure oil is introduced into the hydraulic chamber 39 in order to activate the hydraulic oil 23.

By the way, the control unit 51 is
In order to avoid such a phenomenon that a large torque step is generated during the switching of the cam and the driving performance is deteriorated due to the discontinuous output fluctuation or the vehicle body vibration is induced, the intake passage is provided corresponding to the switching. The opening of the throttle valve 57 and the ignition timing of the ignition device 59 are corrected.

The throttle valve 57 is a servo drive circuit 55 that receives a command signal from the control unit 51,
And a servo motor 5 that operates based on this drive signal
The opening degree is increased / decreased via 6 independently of an accelerator pedal (not shown), and at the same time, the actual opening degree of the throttle valve 57 is fed back to the control unit 51 via the throttle opening sensor 54.

The control unit 51 basically determines the required torque from the signal of the accelerator operation amount sensor 53, and is required to generate the required torque at the cam position at that time obtained from the output of the cam position sensor 58. The throttle opening position is calculated and the opening of the throttle valve 57 is determined via the servo motor 56. When it is determined to switch the cam, when the first cam is switched to the second or third cam, the opening degree of the throttle valve 57 is changed via the servo drive circuit 55 and the servo motor 56, and the torque at the time of the switching is set. It is corrected so as to decrease according to the step, and the increased torque is absorbed. Also, from the second or third cam to the first
When switching to the cam, conversely, the opening of the throttle valve 57 is increased to correct the output in the direction of absorbing the torque step.

At the same time, the control unit 51 retards the ignition timing signal for the ignition device 59 for a fixed time when the cam is switched, thereby correcting the output in the direction of absorbing the torque step.

FIGS. 8 (a) and 8 (b) specifically show how these output corrections are performed. In the former case, when the fuel consumption cam is switched to the output (low speed type) cam, in the latter case, the output cam is operated. This is the case when switching to the fuel economy cam.

As shown in FIG. 8 (a), when the fuel consumption cam is switched to the output cam, the throttle opening (TVO) must be changed before and after the switching as shown by the solid line, the torque is greatly increased, and the boost is increased. (Suction negative pressure) also increases with switching.

On the other hand, when the throttle opening is reduced by a predetermined amount at the time of switching and the ignition timing is temporarily retarded at the time of switching, the torque is the same as before switching, as shown by the chain double-dashed line. It takes a value and the torque fluctuation is absorbed.

Even if the throttle opening is decreased, the torque immediately after the switching transiently increases as compared with the steady state.
This is because the fuel consumption cam is switched to the output cam when the boost is small, and the intake air amount (fuel amount) stored in the cylinder temporarily increases immediately after the switching, and this amount is retarded to reduce the output. It is corrected by this.

When the low speed type output cam is switched to the fuel consumption cam, as shown in FIG. 8 (b), the torque greatly decreases when the throttle opening remains the same, but the throttle opening is indicated by the dotted line. By opening (increasing) by a predetermined amount, it is possible to prevent the torque from dropping, and moreover, by switching from the output cam to the fuel consumption cam with a strong boost immediately before switching, the torque is further reduced immediately before switching. If the throttle is opened in advance and the torque is too large if it is left as it is, the torque fluctuation before and after the switching can be prevented by retarding the ignition timing at the same time.

Thus, the torque fluctuation can be absorbed by performing the output correction in synchronism with the cam switching, but this output correction must be correctly synchronized with the cam switching. At the time of switching from the output cam to the fuel consumption cam, it is necessary to slightly precede the actual output correction with the output correction.

By the way, as described above, since the switching of the cam is performed by utilizing the hydraulic pressure, there is a response delay of the hydraulic system from the output of the switching signal of the cam to the switching of the cam.

Since this response delay time depends on the oil temperature and hydraulic pressure of the hydraulic oil, as shown in FIG. 7, the sensor 61 for detecting the oil temperature T and the upstream hydraulic pressure P of the solenoid valves 45, 46 are set. If a sensor 62 for detection is provided and the response delay time is set in advance according to the oil temperature T and the oil pressure P, the output correction can be performed at the timing according to the switching of the cam.

However, if the hydraulic oil deteriorates due to long-term use, the solenoid valves 45 and 46 and the pins 32 and 3 will be used.
When the operations such as 3 become inactive and the actual response delay time deviates from the preset response delay time, it becomes impossible to absorb the torque step when switching the cam.
For example, if the output correction is actually executed while the cam has not been switched yet, or if the output correction is not executed when the cam has already been switched, a very large torque shock will occur.

Therefore, in the output correction, it is necessary to adjust the timing by looking at the actual response delay time. By doing so, the output correction can be performed in accordance with the actual cam switching, and the torque fluctuation can be reliably absorbed. You can

Therefore, in order to perform the output correction in accordance with the actual cam switching, the control unit 51 actually measures the response delay time from the output of the cam switching signal to the switching of the cam, and this and the predetermined response delay. The timing of the output correction is determined according to the result of comparison with the time, which will be specifically described with reference to the flowchart shown in FIG. It should be noted that this flowchart is executed every time it is judged that the cam is switched.

First, the control waiting cycle number C, the judgment index m, and the n-1 response correction coefficients K1 to Kn-1 up to the previous processing are stored in the memory (step 1).

Again, read the oil temperature T and the oil pressure P,
Based on these, the basic response delay times t _T and t _P are obtained (steps 2-5).

The basic response delay times t _T and t _P are, as shown in FIG. 10, the time t ₁ from the output of the cam switching signal to the actuation of the solenoid valves (hydraulic switching valves) 45 and 46, The time t ₂ from the time when the hydraulic pressure starts to rise (or the time when the hydraulic pressure starts to decrease), and
Etc. are set based on the time t ₃ until the connection (or separation) ends.

Since the response delay time also becomes longer as the oil temperature T becomes lower and the oil pressure P becomes lower, a map having the contents of FIGS. 11 and 12 is prepared and t _T is referred to by referring to this map. Find t _p .

On the other hand, while outputting the cam switching signal, the actual response delay time t from the output timing to the switching of the cam is measured (steps 6 and 7).

This actual response delay time t is determined by the solenoid valves 45, 4
If a sensor 63 for detecting the hydraulic pressure on the downstream side of 6 is provided, it can be easily obtained from the change in the hydraulic pressure. The hydraulic pressure on the downstream side of the solenoid valve rises to a predetermined value after the solenoid valve is switched to switch the cam, but after that the hydraulic pressure temporarily drops due to the movement of the pin and then stabilizes at the predetermined value. Therefore, this temporary decrease is determined from the differential waveform of the hydraulic pressure generated on the downstream side of the solenoid valve.

When the actual response delay time t thus measured is deviated from the basic response delay times t _T and t _P , the solenoid valves 45 and 46 and the pin 3 are caused by deterioration of the hydraulic oil.
It means that the actual operating state of 2, 33, etc. is different from that at the time of initial setting.

At this time, if t> t _T or t> t _P , the cam is switched later than the scheduled timing. Therefore, the output correction timing is also adjusted in accordance with the delayed cam switching timing. I have to delay it.

Therefore, the response correction coefficient K _T related to the oil temperature is calculated from t-t _T, and the response correction coefficient K _P related to the hydraulic pressure is _calculated from t-t.
Obtained from t _P (steps 8 and 9). The characteristics of K _T and K _P are shown in FIGS. 13 and 14, and as the value of t-t _T and t-t _P increases, a larger value of the response correction coefficient is given, and the maps having these characteristics are referred to. Of.

The correction coefficients K _T and K _P thus obtained are calculated by averaging the values of the correction coefficients K _T and K _P.
Then, the weighted average value M for the response correction coefficient is calculated from Kn which is the value of this processing and K1 to Kn-1 which is the values up to the previous processing (steps 10 and 11).
The weighted average value is adopted for the stability of control.

This weighted average value M is compared with the delay judgment index δ read from the memory, and the control waiting cycle number C is updated according to the comparison result.

Here, the "cycle" of the control wait cycle
Is the intake, compression, combustion, and exhaust strokes, and the number of control wait cycles being "1" means that the output is corrected by waiting one stroke from the output of the cam switching signal, that is, the output of the cam switching signal. The output correction start timing is immediately after one stroke from the timing. In the case of a 4-cylinder engine, as shown in FIG. 17, the cam is actually switched in the combustion stroke of the # 1 cylinder, and the value of C at this time is 1.

If the oil temperature T and the oil pressure P are the same, the response delay time of the hydraulic system is almost constant unless the working oil is deteriorated, but when the engine speed N changes, the As shown in, C depends on the engine speed N
The value of changes.

A judgment index is attached to the above-mentioned judgment index δ, and the judgment index (ie, δ) which is accompanied by the judgment index m read from the memory and the exponent m + 1 which is one larger than this.
Between m and δm + 1), compare as follows.

(1) When .delta.m + 1.ltoreq.M It is judged that the actual cam switching timing is behind the set value by the time required for the above-mentioned one stroke or more, and the output correction timing is also delayed. The number C is increased by 1 (steps 12 and 14). The judgment index m is also 1
(Step 15).

(2) When δm ≦ M <δm + 1 Although the actual cam switching is delayed from the set value, it does not exceed the time required for the above one stroke, that is, the current state may be maintained. And the control waiting cycle number C is set to the same value as the previous processing (steps 12, 13, 1).
6). The judgment index m is also made the same as the value of the previous processing (step 17).

(3) When M <δm It is opposite to the case of (1), and it is determined that the actual cam switching is performed more than the time required for one stroke described above, and the number of control waiting cycles is determined. Decrease C by 1 (step 1
2, 13, 18). The judgment index m is also decreased by 1 (step 19).

However, in (3), C after reduction
If the value of is less than or equal to the minimum number of control waiting cycles C ₀ , C
= C _0, and the determination index m is also set to “0” which is the minimum value accordingly (steps 20, 21, 22).

The values of the control waiting cycle number C, the judgment index m, and the response correction coefficients K2 to Kn thus obtained are saved in the memory (step 23).

FIG. 16 shows the relationship between the weighted average value M, the delay judgment index δ, and the control waiting cycle number C.

Although the weighted average value M of the response correction coefficient is not limited to an integer, the control waiting cycle number C must be an integer. That is, in order to determine the control waiting cycle number C according to the weighted average value M which is not limited to an integer, there is a value of M using the delay determination indexes δ0, δ1, δ2, ... It is necessary to give the number of waiting cycles C to the range.

Also, for comparison with the judgment index δ, M
First lies between δ0 and δ1, otherwise δ1 and δ2
, And if it is further between δ2 and δ3 ..., we have to set up almost the same number of judgment steps as the total number of judgment indexes in the program, The capacity will increase accordingly.

On the other hand, when the index m accompanying the judgment index δ is updated according to the result of comparison between M and the judgment index δ, the judgment index δm with the judgment index m at the time of the previous processing is added. And a judgment index δm + 1 having a judgment index m + 1 larger by 1 than that, that is, a step of comparing only the two judgment indexes.

Specifically, δ0 = 0, δ1 = 1.5, δ2
= 3.0, δ3 = 4.5 ... And M = 2.1, δ1 <M <δ2. At this time, the index m = 1 attached to the determination index δ1 is stored in the memory, and when the next cam switching determination is made, it is determined whether M ≧ δ2, δ1 ≦ M <δ2, or M <δ1.

On the other hand, the saved value of C is read by another program (not shown), and the control waiting time from there to the output correction timing is calculated with reference to the output timing T ₁ of the cam control signal. In the case of a 4-cylinder engine, the control waiting time T ₂ until the throttle opening correction is T ₂ = (C × 180) / (360N / 60) sec, and the control waiting time T ₃ until the ignition timing correction is T ₃ = It is calculated by (C × 180 + 360) / (360N / 60) sec.

The numerator of both formulas, C × 180, is a value obtained by converting the control waiting cycle number C into a crank angle, and the cam switching signal is output not in the top dead center or the bottom dead center but in the middle of one stroke. At this time, as shown in FIG. 17, the crank angle up to the intake bottom dead center is not considered. However, the crank angle of 180 ° or less can be easily obtained from the output of the crank angle sensor.

Further description will be given with reference to FIG. The engine speed N is constant.

For the # 1 cylinder, when the cam is actually switched in the combustion stroke, the memory storing the control waiting cycle number C contains 1 as shown in the figure, and T ₂ calculated from the value of C throttle opening is small at the timing after the, also is controlled by the ignition timing relative to the cam after switching after the time after the T _3.

From this state, operation failure occurs in the hydraulic system due to long-term use of hydraulic oil, and even under the same operating conditions, the cam does not switch in the combustion cycle in which the cam switching signal is output, as indicated by the broken line in the figure. It is assumed that the switching is finally performed in the exhaust stroke of the next combustion cycle delayed by 720 °, and the actual response delay time is increased by 720 °, that is, the number of four cycles.

Also at this time, if the output correction is executed at the same timing as before the hydraulic system malfunctions, the cam has not actually been switched yet, so that a very large torque shock may occur. It will be.

On the other hand, in this example, due to the deviation of the actual response delay time from the set value, the value of C is increased by 1 each time the switching of the cam is judged, and eventually the value of C becomes 5. It is rewritten and calms down. As a result, the correction timing of the throttle opening is also delayed by four cycles as shown by the broken line in the figure, and corresponds to the cam switching timing when the malfunction occurs.

That is, if a basic response delay time is set according to the oil temperature T and the oil pressure P, and if there is a deviation between this time and the actual response delay time, the actual cam switching timing at which the deviation has occurred is set. At the same time, the output correction timing is changed.

As a result, even if the hydraulic system deteriorates due to deterioration of the hydraulic oil and the actual response delay time deviates from the basic response delay time set by the initial setting, the torque step at the time of switching the cam is accurately determined. Can be absorbed into.

Further, in this example, the value of the determination index is moved by rewriting the index accompanying the determination index each time while checking the current state, so is it possible to use the current value of C? If it is possible to determine whether the value of C should be larger or smaller than the current value, it is not necessary to compare with a further judgment index. That is, since the determination index is always two, δm and δm + 1, the program is simplified and the memory capacity can be reduced accordingly.

When the cam switching timing overlaps the intake stroke of the # 1 cylinder due to the output timing of the cam switching signal even when the engine speed is constant, or when the engine speed increases even when the output timing of the cam switching signal is constant, Since the cam switching for the # 1 cylinder is delayed until the subsequent compression stroke, the output correction for the # 1 cylinder may be for the cam after switching, even though the cam is the cam before switching at this time.

However, as disclosed in Japanese Patent Application No. 2-305685, such a point can be dealt with by determining the output timing of the cam switching signal so that the cam switching timing does not overlap the intake stroke. it can.

The relationship between the flowchart and FIGS. 1 and 2 is as follows. 9, steps 2 to 5 are basic response delay time setting means 79, step 7 is actual response delay time measuring means 80, steps 8 to 23 and 1 are output correction timing advancing and retarding means 81, and steps 8 to 11 are response correction amounts. The calculating means 91, steps 12 and 13 function as comparing means 93, steps 14 to 19 function as cycle number / index updating means 94, and step 23 functions as cycle number / index storing means 95.

[0089]

According to the first aspect of the present invention, the actual response delay time from the output of the cam switching signal to the cam switching is measured, and the actual response delay time is more than the set value depending on the difference between the actual response delay time and the set value. If it is long, the output correction timing will be delayed, and conversely, if it is shorter than the set value, the output correction timing will be advanced.
Even if the hydraulic switching valve malfunctions due to deterioration of hydraulic oil due to long-term use, it is possible to correct the output according to the actual cam switching and absorb the torque step during cam switching. it can.

The second aspect of the present invention is that when the response correction amount corresponding to the deviation between the actual response delay time and the set value is compared with the determination index associated with the index, the index associated with the index that is larger than the index by one last time is used. If the response correction amount is greater than the determined index, the previous control waiting cycle number and index are increased by one, and if the response correction amount is smaller than the determination index associated with the previous index, the previous control waiting cycle number and index are calculated. If it is smaller by 1 and the response correction amount is greater than or equal to the determination index associated with the previous index and smaller than the determination index associated with the index greater by 1, the previous control waiting cycle number and index are maintained and updated. The number of control wait cycles and the index are stored while the output correction timing is determined according to the updated number of control wait cycles. Even when caused the malfunction such as a valve, it is possible to output corrected to match the actual cam switching,
It is possible to absorb the torque step at the time of switching the cam, and since there are two judgment indexes used for comparison with the response correction amount this time, the program becomes simple and the memory capacity is reduced accordingly. be able to.

[Brief description of drawings]

FIG. 1 is a diagram corresponding to claims of the first invention.

FIG. 2 is a diagram corresponding to a claim of the second invention.

FIG. 3 is a plan view of a variable valve operating device according to an embodiment.

4 is a sectional view taken along line XX of FIG.

FIG. 5 is a characteristic diagram of a valve lift of the device.

FIG. 6 is a characteristic diagram of full-open torque of the device.

FIG. 7 is a configuration diagram of a control system of the embodiment.

FIG. 8 is a waveform diagram showing how the torque changes when the cam is switched.

FIG. 9 is a flow chart for explaining a control operation of the embodiment.

FIG. 10 is an explanatory diagram showing setting of a response delay time.

FIG. 11 is a characteristic diagram showing the contents of a map of basic response delay time t _T.

FIG. 12 is a characteristic diagram showing the contents of a map of basic response delay time t _P.

FIG. 13 is a characteristic diagram showing the contents of a map of response correction coefficient K _T.

FIG. 14 is a characteristic diagram showing the contents of a map of a response correction coefficient K _P.

FIG. 15 is a characteristic diagram showing the contents of a map of the control waiting cycle number C.

FIG. 16 is a characteristic diagram showing a relationship between the determination index δ and the number C of cycles waiting for control.

FIG. 17 is a waveform diagram for explaining the operation of the embodiment.

[Explanation of symbols]

 21 1st cam (fuel consumption cam) 22 2nd cam (low speed type output cam) 23 3rd cam (high speed type output cam) 24 intake / exhaust valve 25 main rocker arm 28,29 sub rocker arm 32-35 pin 38,39 Hydraulic chamber 45,46 Solenoid valve (hydraulic switching valve) 51 Control unit 52 Crank angle sensor (engine speed sensor) 53 Accelerator operation amount sensor 54 Throttle opening sensor 56 Servo motor 57 Throttle valve 58 Cam position sensor 61 Oil temperature sensor 62 Upstream oil pressure sensor 63 Downstream oil pressure sensor 71 Cam 72 Cam switching mechanism 73 Operating condition sensor 74 Cam switching determination means 75 Switching signal output means 76 Output correction means 77 Oil temperature sensor 78 Oil pressure sensor 79 Basic response delay time setting means 80 Actual response Delay time measuring means 81 Output correction Timing advance / retard means 91 Response correction amount calculation means 92 Judgment index generation means 93 Comparison means 94 Cycle number / index update means 95 Cycle number / index storage means 96 Output correction timing determination means

Claims (2)

[Claims] 1. A plurality of cams having cam profiles having different output characteristics, and a cam switching mechanism for selectively switching these cams by operating a hydraulic switching valve and transmitting the motion of the cams to at least one of intake and exhaust valves. A sensor for detecting an operating condition, a means for judging whether or not the cam is switched according to the operating condition, and a cam switching signal when the cam switching is judged from the judgment result. In the engine having means for outputting to the valve and means for correcting the engine output so that the generated torque before and after switching when the cam is switched are the same, the temperature and pressure of the hydraulic oil supplied to the hydraulic switching valve A sensor for detecting the above, a means for presetting a basic response delay time from the output of the cam switching signal to the cam switching according to the detected values, Means for measuring the actual response delay time from the output of the system switching signal to the cam switching, and the output if the actual response delay time is longer than the basic response delay time according to the difference between the actual response delay time and the basic response delay time. An output control apparatus for an engine, characterized in that means for delaying the correction timing and, conversely, advancing the output correction timing when the time is shorter than the basic response delay time. 2. A plurality of cams having cam profiles having different output characteristics, and a cam switching mechanism for selectively switching these cams by operating a hydraulic switching valve and transmitting the motion of the cams to at least one of intake and exhaust valves. A sensor for detecting an operating condition, a means for judging whether or not the cam is switched according to the operating condition, and a cam switching signal when the cam switching is judged from the judgment result. In the engine having means for outputting to the valve and means for correcting the engine output so that the generated torque before and after switching when the cam is switched are the same, the temperature and pressure of the hydraulic oil supplied to the hydraulic switching valve A sensor for detecting the above, a means for presetting a basic response delay time from the output of the cam switching signal to the cam switching according to the detected values, Means for measuring the actual response delay time from the output of the system switching signal to the cam switching, and the actual response delay time is longer than the basic response delay time according to the difference between this actual response delay time and the basic response delay time. A means for calculating a larger response correction amount, a means for generating a determination index associated with an index, a means for comparing the determination index with the response correction amount, and an index larger than the previous index by one from the comparison result. If the response correction amount is larger than the judgment index associated with, the previous control wait cycle number and the previous index are increased by one,
If the response correction amount is smaller than the determination index associated with the previous index, the previous control wait cycle number and the previous index are reduced by one, and the response correction amount is greater than or equal to the determination index associated with the previous index and only 1 above. If it is smaller than the judgment index accompanied by a large index, the means for maintaining the previous control waiting cycle number and the previous index, the means for storing the updated control waiting cycle number and the index, and the updated control waiting cycle An output control device for an engine, comprising: a means for determining the timing of the output correction in accordance with the number.