JPH02115536A - Control device for engine with supercharger - Google Patents

Abstract

PURPOSE:To synchronize always the completion of switching the intake and exhaust overlap period and the start of supercharging by setting the time difference between the time from the start of switching the intake and exhaust overlap period to the start of switching a clutch of a mechanical supercharger, and the engine speed becomes lower, changing this time difference larger. CONSTITUTION:Since the time difference is set by a timer means 64 between the time from the start of switching a timing change device 30 by a timing switching means 62 to the start of switching a clutch 44 by a clutch switching means 63, at the time of switching to the supercharging area, the supercharging is started after the increasing of the intake and exhaust overlap period. In this case, since the engine speed becomes lower, the time difference of the timer means 64 is changed larger, even if the engine speed lowers and the oil pressure lowers in response of it so that the action delay of the timing change device 30 is increased, the completion of switching the intake and exhaust overlap period and the start of supercharging are always synchronized so that the generation of knocking and the generation of the torque shock are prevented.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a control device for a supercharged engine, and particularly to a control device for a supercharged engine.
This invention relates to a system in which the exhaust overlap period is changed and the re-engine is supercharged by a mechanical supercharger.

(Prior Art) Conventionally, as a control device for a supercharged engine, a mechanical supercharger is provided in an intake passage, and the supercharger is connected to a clutch, as disclosed in Japanese Patent Laid-Open No. 61-197720, for example. The clutch is connected to the engine output shaft through the supercharging range, which is centered on high-speed, high-load ranges, and the clutch is connected to supercharge the engine and increase its output, while the clutch is disengaged outside the supercharging range mentioned above. The engine is operated with naturally aspirated air to reduce fuel consumption. In addition, a timing change device that is driven by a step motor and that makes the intake/exhaust timing variable is installed in the engine's valve train system to make the intake/exhaust overlap period variable. Increase the intake/exhaust overlap period,
The occurrence of knocking is suppressed by reducing the effective stroke of the piston to substantially lower the compression ratio. In that case, since the timing change device has an operation delay, for example, when entering the supercharging region, the timing change device increases the intake/exhaust overlap period, and then a delay time corresponding to the above operation delay is set. By performing a delay process in which the clutch of the mechanical supercharger is connected later, supercharging is avoided from starting while the intake/exhaust overlap period is still small, thereby preventing the occurrence of knocking.

(Problem to be Solved by the Invention) By the way, when the timing change device is driven by oil pressure generated by the engine, the oil pressure changes according to fluctuations in the engine speed, so it is not affected by this oil pressure change. Therefore, the delay in the operation of the timing change device is not constant, and the effect of the delay processing described above cannot be obtained satisfactorily. In other words, when the delay in operation increases, the delay time is insufficient, so the suction
There is a problem in that when the exhaust overlap period remains small, supercharging is started and knocking occurs, whereas when the operation delay is reduced, the intake/exhaust overlap period changes suddenly and torque shock occurs.

The present invention has been made with attention to these points,
The purpose of this is to always synchronize the completion of switching of the intake/exhaust overlap period and the start of supercharging by correcting the delay time according to fluctuations in engine speed that are correlated with changes in oil pressure.

(Means for Solving the Problems) In order to achieve the above object, the present invention sets a time difference between the start of switching the intake/exhaust overlap period and the start of switching the clutch of the mechanical supercharger. The purpose is to change the time difference to a greater extent as the engine speed decreases.

Specifically, the solution taken by the present invention, as shown in FIG. a mechanical supercharger 17; an operating state detection means 61 for detecting the operating state of the engine;
Timing switching means 62 receives the output of the operating state detection means 61 and switches the timing change device 30 so that the intake/exhaust overlap period increases when transitioning to a supercharging region and decreases when transitioning to a region other than the supercharging region; , a clutch switching means 63 which receives the output of the operating state detecting means 61 and switches the clutch 44 to be connected when transitioning to supercharging head loading and disconnected when transitioning to a region other than the supercharging region, and timing changing device 30. A timer means 64 is provided for setting a time difference between the start of switching of the device 30 and the start of switching of the clutch 44 by the clutch switching means 63, and the time difference of the timer means 64 is changed more as the engine speed becomes lower. This is what I did.

(Function) With the above configuration, in the present invention, the clutch switching means 63
Under this control, in the supercharging region, the clutch 44 is connected and the engine is supercharged to increase its output, while in other than the supercharging region, the clutch 44 is disengaged and the engine is operated with natural intake, reducing fuel consumption, etc. is planned.

In addition, the timing switching means 62 controls the intake/exhaust overlap period in the supercharging region, thereby preventing the occurrence of knocking, increasing the fuel efficiency improvement effect of internal EGR, and promoting scavenging of residual gas in the cylinder. be done.

Then, by the timer means 64, the timing switching means 6
Since a time difference is set between the start of switching of the timing change device 30 by 2 and the start of switching of the clutch 44 by the clutch switching means 63, at the time of transition to the supercharging region,
Supercharging is started after the intake/exhaust overlap period has increased.

In that case, the time difference of the timer means 64 is changed more as the engine speed decreases, so even if the engine speed decreases and the oil pressure decreases accordingly, the delay in the operation of the timing change device 30 increases. The completion of switching the intake/exhaust overlap period and the start of supercharging are always synchronized, thereby preventing the occurrence of knocking and torque shock.

(Example) Embodiments of the present invention will be described below based on the drawings.

FIG. 2 shows a DOH equipped with a control device according to an embodiment of the present invention.
This shows a C type supercharged engine. In the same figure, 1
2 is an engine, and 2 is a cylinder formed in the engine. A piston 3 is slidably fitted into the cylinder 2, and a combustion chamber 4 is formed by the cylinder 2 and the piston 3. The piston 3 is connected to a crankshaft 6 via a connecting rod 5. Also, 7
One end is connected to the combustion chamber 4 and the other end is connected to the air cleaner 8.
An intake passage 9 is open to the atmosphere through the intake passage 9, and an exhaust passage 9 has one end connected to the combustion chamber 4 and the other end open to the atmosphere.

An intake valve 11 is disposed at the opening of the intake passage 7 to the combustion chamber 4, and an exhaust valve 12 is disposed at the opening of the exhaust passage 9 to the combustion chamber 4. The intake valve 11 and the exhaust valve 12
are driven by the intake camshaft 13 and the exhaust camshaft 14 at predetermined timings, respectively.

The intake passage 7 also includes, in order from the upstream side of the intake air, a throttle valve 16 for adjusting the intake flow rate, a mechanical supercharger 17 for pressurizing the intake air, and a surge tank 18.
An injector 19 is provided for injecting and supplying fuel to the intake air. Furthermore, a supercharger 17 is provided in the intake passage 7.
A bypass passage 21 is provided to bypass the supercharger 1, and a control valve 22 is provided in the bypass passage 21.
When the engine 7 is stopped, the control valve 22 is opened to supply intake air to the combustion chamber 4 via the bypass passage 21.

Further, the exhaust camshaft 14 is provided with a timing change device 30 that makes the exhaust timing variable. That is, as shown in FIG. 1, the camshaft 14 is divided into a drive gear part 31 that receives the driving force from the crankshaft 6 and a driven part 32 other than the drive gear part 31. Helical gears are formed in opposing parts of the driving gear part 31 and the driven part 32, respectively, and a sleeve 33 is provided so as to straddle and mesh with these helical gears.
Actuator 3 driven by engine oil pressure
4 in the camshaft direction, the rotational phase between the driving gear section 31 and the driven section 32 is adjusted to make the exhaust timing variable (see Fig. 3).
. Note that the timing changing device may be provided on the intake camshaft 13.

Further, a driven pulley 41 is attached to the drive shaft 17a of the mechanical supercharger 17, and a crank pulley 42 is attached to the crankshaft 6, and a belt 43 is attached between the driven pulley 41 and the crank pulley 42. is wound around the crankshaft 6, and a mechanical supercharger 17 is driven by the crankshaft 6.

An electromagnetic clutch 44 is provided on the drive shaft 17a of the mechanical supercharger 17, and the mechanical supercharger 17 is activated or stopped by connecting or disconnecting the electromagnetic clutch 44.

The timing change device 30 and the electromagnetic clutch 44 are controlled by a control unit 50. Further, 51 is an air flow meter provided in the intake passage 7 to detect the intake air flow rate, and 52 is a rotation speed sensor provided in the engine 1 to detect the engine rotation speed. Output signals from these sensors 51 and 52 are input to the control unit 50.

Next, the operation control of the control unit 50 will be explained based on the flow shown in FIG. 4. In the figure, after the start, various data are first read in step S1, and in step S2 the engine is in the supercharging region shown in FIG.
If the answer is YES in the supercharging region, it is determined in step S3 whether the intake/exhaust overlap period is actually large. When the result is NO, it is determined that it is time to shift to the supercharging region, and a large overlapping signal is output in step S4. As a result, switching of the timing change device 30 is started to increase the intake/exhaust overlap period, and upon completion of the switching, the occurrence of knocking is prevented, and the fuel efficiency improvement effect of internal EGR is enhanced, and the internal EGR is increased. Scavenging of residual gas is promoted.

Furthermore, in step S5, a time difference according to the engine speed is calculated from the delay time table, and this time difference is counted in the next step S6. When the count up is reached, the electromagnetic clutch 44 is connected in step S7 to supercharge the engine. start and increase its output. Here, the delay time table is set so that the lower the engine speed, the larger the time difference, as shown in FIG. 6. Since there is a time difference between when the timing change device 30 starts switching and when the electromagnetic clutch 44 is connected, supercharging is started after the intake/exhaust overlap period has increased. This prevents knocking from occurring.

In that case, the lower the engine speed is, the larger the time difference is changed, so even if the engine speed is lower and the oil pressure is correspondingly lowered and the delay in the operation of the timing change device 30 increases, the intake/exhaust overlap The completion of period switching and the start of supercharging are always synchronized, thereby preventing the occurrence of knocking and torque shock.

On the other hand, if the result in step S3 is YES, indicating that the intake/exhaust overlap period is actually large, the process immediately proceeds to step S7 to maintain the connection of the electromagnetic clutch 44.

Also, if the engine is not in the supercharging region in step S2 above, the N
If it is determined as o, it is determined in step S8 whether or not the intake/exhaust overlap period is actually small, and if N is large, it is determined in step S8.
When it is O, it is determined that it is time to shift to a region other than the supercharging region, and a small overlap signal is output in step S9. As a result, the timing change device 30 starts switching so that the intake/exhaust overlap period becomes smaller.

Furthermore, in step SIO, a time difference according to the engine speed is calculated from the above-mentioned delay time table, and this time difference is counted in the next step Sl+, and when the count is up, step S! At step 2, the electromagnetic clutch 44 is disengaged to stop engine supercharging, and the engine is operated with natural intake to reduce fuel consumption. In this way, since there is a time lag between the start of switching of the timing change device 30 and the connection of the electromagnetic clutch 44, supercharging is stopped after the intake/exhaust overlap period is reduced.

Even in that case, the lower the engine speed, the greater the time difference is changed, so the lower the engine speed, the lower the oil pressure correspondingly, and the timing change device 3.
Even if the 0 operation delay increases, the completion of switching the intake/exhaust overlap period and the stop of supercharging are always synchronized.

On the other hand, if the result in step S8 is YES, indicating that the intake/exhaust overlap period is actually small, the process immediately proceeds to step S12 to maintain the separation of the electromagnetic clutch 44.

In the above flow, step S1 constitutes the operating state detection means 61 that detects the operating state of the engine. Moreover, by step S4 and step S9,
A timing switching means 62 receives the output of the operating state detection means 61 and switches the timing change device 30 so that the intake/exhaust overlap period increases when transitioning to a supercharging region and decreases when transitioning to a region other than the supercharging region. It consists of Furthermore, in step S7 and step S12, the output of the operating state detection means 61 is received, and the clutch 44
Clutch switching means 63 is configured to connect the clutch at the time of transition to the supercharging region and to disconnect at the time of transition to a region other than the supercharging region. Further, step S6 and step S11 constitute a timer means 64 that sets a time difference between when the timing switching means 62 starts switching the timing changing device 30 and when the clutch switching means 63 starts switching the clutch 44.

(Effects of the Invention) As explained above, according to the control device for a supercharged engine of the present invention, a timing change device that changes intake timing or exhaust timing, and a timing change device that is connected to an engine output shaft via a clutch are provided. In addition, the intake/exhaust overlap period is increased when transitioning to the supercharging region and decreased when transitioning to a region other than the supercharging region, and the clutch is It connects and separates when transitioning to a region other than the supercharging region, and also sets a time difference between the start of switching of the timing change device and the start of switching of the clutch, and this time difference is changed to a larger value as the engine speed decreases. By engaging and disengaging the clutch, we aim to improve engine output and reduce fuel consumption, and by operating the timing change device, we obtain basic effects such as preventing the occurrence of knocking, and also complete the switching of the intake/exhaust overlap period and start supercharging. By always synchronizing the two, it is possible to prevent knocking and torque shock from occurring.

[Brief explanation of drawings]

FIG. 1 is a block diagram showing the configuration of the present invention. 2 to 6 illustrate embodiments of the present invention, FIG. 2 is an overall schematic diagram, FIG. 3 is an explanatory diagram showing the operation of the timing change device, and FIG. 4 is an illustration of the operation control of the control unit. FIG. 5 is an explanatory diagram showing the supercharging region, and FIG. 6 is an explanatory diagram showing the delay time table. 17... Mechanical supercharger, 30... Timing change device, 44... Electromagnetic clutch, 61... Operating state detection means, 62... Timing switching means, 63... Clutch switching means, 64...Timer means.

Claims (1)

[Claims] (1) A timing change device that varies the intake timing or exhaust timing, a mechanical supercharger connected to the engine output shaft via a clutch, an operating state detection means that detects the operating state of the engine, and an operating state Timing switching means receives the output of the detection means and switches a timing change device so that the intake/exhaust overlap period increases when transitioning to a supercharging region and decreases when transitioning to a region other than the supercharging region; and an operating state detecting means. Clutch switching means receives the output of the clutch and switches the clutch to be connected when transitioning to the supercharging region and disengaged when transitioning to a region other than the supercharging region; A control device for a supercharged engine, characterized in that a timer means is provided for setting a time difference until the start of switching, and the time difference of the timer means is changed more greatly as the engine speed becomes lower.