JPH0134665Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Field of Industrial Application) This invention relates to an intake air amount control device for a Miller cycle engine equipped with a supercharger.

(Prior Art) There is a so-called Miller cycle as a means for improving the output of a gasoline engine or a diesel engine. This is to close the intake passage at a point before the bottom dead center of the piston, thereby causing adiabatic expansion from this point to the bottom dead center. Therefore, when this Miller cycle is applied to an existing normal cycle engine, the compression pressure at top dead center decreases while the expansion ratio remains the same, reducing the mechanical load (maximum pressure in the thermal combustion chamber). ) and heat load (combustion temperature) are reduced while the power output remains the same.

By attaching a supercharger to a mirror cycle like this,
If the compression pressure at top dead center is made comparable to the normal cycle (Otto cycle), the mechanical load and thermal load will be the same, but the output will increase. Especially for diesel engines, it is effective to use a Miller cycle with a supercharger to improve output.

Therefore, the normal cycle is used when the engine's mechanical load and thermal load are lower than the specified mid-speed engine speed, while the mirror cycle is used at high speeds above the above specified engine speed where the mechanical load and thermal load are large. It closes just before the dead center, and
It is known that an adjustment device is installed to make the point at which this intake passage closes earlier as the rotational speed increases, thereby reducing the air supply amount and fuel supply amount (Japanese Patent Laid-Open No. 55-148932). (see publication).

In this way, the mechanical load and thermal load due to supercharging can be suppressed to a predetermined level, and a decrease in reliability can be suppressed, but even when accelerating, the charging efficiency decreases, making it impossible to obtain large torque, and accelerating. There is a drawback that performance cannot be improved.

(Purpose of the invention) This invention was made to eliminate the above-mentioned conventional drawbacks, and as a Miller cycle, it increases output while suppressing the decline in engine reliability.
It is an object of the present invention to provide an intake air amount control device for a supercharged engine that can also improve acceleration performance.

(Structure of the invention) In order to achieve the above object, this invention has an adjustment device that advances the closing timing of the opening/closing valve of the intake passage as the engine speed increases. By adding an opening/closing timing delay device to slow down the speed, a large torque can be obtained during acceleration.

(Example) Hereinafter, an example of this invention will be described with reference to the drawings.

FIG. 1 shows the first embodiment, where 11 is a multi-cylinder four-stroke diesel engine body;
An intake passage 12 and an exhaust passage 13 are connected to this engine body 11. 14 is a supercharger, which is driven by the exhaust gas 15 in the exhaust passage 13 and is driven by the exhaust gas 15 in the exhaust passage 13;
The pressure of the intake air 16 of No. 2 is increased.

In the intake passage 12, in addition to the intake valve (not shown), an on-off valve 17 consisting of a cylindrical rotary valve is rotatably provided via a bearing 18. 19 faces the intake passage 12, the intake passage 12 is opened. The on-off valve 17 is controlled by the adjustment device 21
and a timing pulley 23 via a valve closing timing delay device 22, and this timing pulley 23 is connected to the crankshaft 2 by a blade-shaped belt 24.
5 is connected to the output pulley 26 of the crankshaft 2.
It rotates at 1/2 the rotation speed of 5.

The adjustment device 21 includes a valve shaft 29 and an intermediate shaft 30 that are integrally formed with the on-off valve 17 at one end (right end).
30a, an arm 34 that is rotatably supported around a support shaft 32 and moves the connecting tube 31 in the axial direction by rotation, and an actuation rod 35 that is connected to this arm 34. It has a cylinder device 36 that rotates the arm 34, and an introduction pipe 37 that introduces intake pressure from the downstream side of the supercharger 14 in the intake passage 12 to the cylinder device 36. The above valve shaft 29 and intermediate shaft 30
A helical spline H twisted in opposite directions is formed at one end 30a, and protrusions 38 and 39 protruding from the inner surface of the connecting pipe 31 are engaged with these helical splines H, so that the intermediate The rotational force of the shaft 30 is transmitted to the valve shaft 29 via the connecting pipe 31.
At the same time, the connection pipe 31 is transmitted to the right direction 33.
When moving to position a, the valve shaft 29 is angularly displaced in a certain direction relative to the intermediate shaft 30 to advance the closing timing of the on-off valve 17, and when the connecting pipe 31 is moved to the left 33b, the valve shaft 29 is moved in the opposite direction. The valve is angularly displaced to delay the closing timing of the on-off valve 17.

The tip of the operating rod 35 of the cylinder device 36 is connected to the control lever 4 of the fuel injection pump 41.
2, and the left direction 4 of the actuating rod 35
By moving to 3, the amount of fuel injected from the fuel injection pump 41 is reduced.

The valve closing timing delay device 22 includes a rotating shaft 44 fixed to the timing pulley 23, and a rotating shaft 44 fixed to the timing pulley 23.
A spring member 4 is inserted into the hollow part of 4 and presses the other end (left end) 30b of the intermediate shaft 30 in the right direction 33a.
5, and a protrusion 46 protruding from the inner surface of the rotating shaft 44 is connected to the other end 30b of the intermediate shaft 30.
By engaging the spiral groove S formed in the
The rotational force of the rotating shaft 44 is transmitted to the intermediate shaft 30, and as will be described later, the adjustment device 2
1 is slowed down to suppress the advance of the closing timing of the on-off valve 17.

In the above configuration, when the engine speed increases, the flow rate of the exhaust gas 15 increases and the rotation speed of the supercharger 14 also increases, which increases the supercharging pressure, that is, the intake passage 1
The pressure downstream of the supercharger 14 at 2 increases. This increase in pressure causes the actuating rod 35 of the cylinder device 36 to move to the left 43, causing the arm 3
4 clockwise to move the connecting pipe 31 to the right.
3a, thereby angularly displacing the valve shaft 29, that is, the on-off valve 17, to advance the opening and closing timings of the on-off valve 17. At this time, by appropriately setting the magnitude of the spring force of the adjustment spring 50 that presses the piston 49 in the cylinder device 36, the on-off valve 17 The closing timing of the intake valve does not advance, and the opening/closing timing of the intake valve and the opening/closing timing of the opening/closing valve 17 are set to be almost the same, resulting in a normal cycle that is not a Miller cycle. As shown in the figure, a mirror cycle can be achieved by advancing the closing timing of the on-off valve 17 relative to the intake valve and closing the on-off valve 17 earlier than near the bottom dead center when the intake valve closes.

When the opening/closing timing of the on-off valve 17 is advanced as shown in FIG. 3, the time during which both the on-off valve 17 and the intake valve are open becomes shorter, and the amount of intake air per cycle is accordingly reduced. Here, since the opening timing _T1 of the on-off valve 17 is within the closing period of the intake valve, the earlier or later opening timing is unrelated to the intake air amount, and the closing timing T1 of the on-off valve 17 is within the closing period of the intake valve. Only ₂ affects the amount of intake air.

While the amount of intake air decreases, the actuating rod 35 of the cylinder device 36 rotates the control lever 42 of the fuel injection pump 41 counterclockwise, reducing the amount of fuel injected per cycle.
In this way, above a certain number of revolutions, the intake air amount and fuel injection amount per cycle decrease as the number of revolutions increases, so the maximum pressure (combustion pressure) in the combustion chamber remains almost constant above a certain number of revolutions. The following pressure characteristics are obtained. Therefore, the mechanical load and thermal load on the engine are prevented from becoming excessive at a predetermined rotation speed or higher.

Next, when the engine speed suddenly increases during acceleration, the rotation speed of the timing pulley 23 shown in FIG. Therefore, the intermediate shaft 30 cannot follow the above speed increase,
It rotates counterclockwise 53 with respect to the rotation axis 44 . In other words, an angular delay occurs in the intermediate shaft 30. At this time, the spiral groove S of the intermediate shaft 30 is connected to the protrusion 4 of the rotating shaft 44.
6, the intermediate shaft 30 is engaged with the spring member 4.
It moves to the left direction 33b against the spring force of 5. On the other hand, since the intake pressure increased due to sudden acceleration is acting on the cylinder device 36 of the adjusting device 21 via the introduction pipe 37, the arm 34 moves the connecting pipe 31 to the right 33a and closes the valve shaft 29. The operating speed of the adjusting device 21 is slowed by the angular delay of the intermediate shaft 30 of the valve closing timing delay device 22. It is. In this way, the operating speed of the adjustment device 21 is slowed only during sudden acceleration, and the suppression of the intake air amount and fuel injection amount is delayed. As a result, charging efficiency is increased, combustion pressure is increased, and torque is increased, thereby improving acceleration performance. . The temporarily delayed operation of the regulator 21 is restored after the rapid acceleration ends, and the combustion pressure decreases. Here, since the increase in combustion pressure is within a short period of time, the mechanical load and thermal load on the engine are only temporarily increased, so overall reliability of the engine is not reduced.

The valve closing timing delay device 22 in FIG.
How much to slow down the operating speed of the spring member 4
It is determined by the selection of the spring constant of 5. If this spring constant is increased, the amount of movement of the intermediate shaft 30 in the left direction 33b will be reduced, the angular delay of the intermediate shaft 30 will be correspondingly reduced, and the effect of delaying the operation speed will be reduced. Conversely, if the spring constant is made smaller, the effect of delaying the actuation speed becomes greater.

FIG. 4 shows a second embodiment of this invention, in which the valve closing timing delay device 22 includes first and second diaphragms 56, 57 in a case 55 and a partition wall 58 located between them. attached to form first and second oil chambers 59, 60 filled with oil, and connect the actuating rod 35 of the cylinder device 36 of the adjusting device 21 to the actuating rod 64 of the first diaphragm 56; The second diaphragm 57 is pressed toward the first diaphragm 56 side (right side) by the spring member 61, and the partition wall 5
8, a throttle 6 that communicates between both oil chambers 59 and 60.
2 and the second oil chamber 60 to the first oil chamber 5
A reed valve 63 is provided that allows oil to flow in only one direction toward the oil pump 9.

According to this embodiment, during normal operation, not during acceleration, the actuating rod 35 of the cylinder device 36 moves to the left 43 as the engine speed increases, and the opening/closing valve 1 is moved by the action of the arm 34 and the connecting pipe 31.
The closing timing of the valve 7 is advanced to reduce the amount of intake air, and the amount of fuel injected from the fuel injection pump 41 is also reduced. On the other hand, during acceleration, the actuating rod 35 of the cylinder device 36 suddenly moves to the left 43.
However, since the oil in the first oil chamber 59 only flows into the second oil chamber 60 from the throttle 62, the first diaphragm 56 connected to the actuating rod 35 moves in the left direction 43. The actuating rod 35 becomes difficult to bend, and movement of the actuating rod 35 in the left direction 43 is therefore braked. In other words, the operating speed of the adjustment device 21 becomes slower. Note that when the actuating rod 35 retreats to the right 65, the oil in the second oil chamber 60 is pushed back to the right 65 via the second diaphragm 57 by the spring force of the spring member 61, and the reed valve 63
It returns to the first oil chamber 59 through.

In each of the above embodiments, a rotary valve is used as the on-off valve 17, but unlike this, a new camshaft and a mushroom valve may be used, or the intake valve or intake passage throttle valve itself may be used as an on-off valve. The timing of closing the valve may be controlled by using the same.

Further, as another example of the valve closing timing delay device 22,
The acceleration state is detected by calculating the fluctuation in engine speed detected by the rotation sensor, and the detection signal is used to
In some cases, a pin 66 shown by a two-dot chain line protrudes near the arm 34 in FIG. 4 to prevent the arm 34 from rotating, or in the actuating rod 35 or arm 34, a dead zone is provided that does not operate only during acceleration. be.

(Effects of the invention) As explained above, according to this invention, a mirror cycle is realized, which makes it possible to improve engine output while suppressing increases in the mechanical load and thermal load of the engine, and at the same time, during acceleration. Large torque is obtained and acceleration performance is improved.

[Brief explanation of the drawing]

Fig. 1 is a schematic configuration diagram showing the first embodiment of this invention, Figs. 2 and 3 are timing diagrams showing the opening/closing timing of the on-off valve and intake valve in the same embodiment, and Fig. 4 is the second embodiment. FIG. 1 is a schematic configuration diagram showing an example. 12...Intake passage, 14...Supercharger, 17...
Opening/closing valve, 21...Adjusting device, 22...Valve closing timing delay device.

Claims (1)

[Scope of utility model registration request] Intake air for a supercharged engine that is equipped with an on-off valve in the intake passage and an adjustment device that adjusts the closing timing of the on-off valve so that the closing timing of the on-off valve is advanced as the engine speed increases. An intake air amount control device for a supercharged engine, characterized in that the amount control device is provided with a valve closing timing delay device that slows down the operating speed of an adjustment device that advances the closing timing of the on-off valve during acceleration.