JPH0324841Y2 - - Google Patents

Description

[Detailed Description of the Invention] (Field of Industrial Application) The present invention relates to an engine intake flow rate control device.

(Prior art) An example of an engine intake flow rate control device was published in Japanese Patent Application Laid-open No. 55
-Described in Publication No. 148932. This intake flow rate control device includes a rotary valve in the intake passage upstream of the intake valve, and controls the intake flow rate by shifting the opening timing of the rotary valve depending on the operating state of the engine. In other words, in this conventional technology, as the engine load and supercharging pressure increase in a supercharged engine, the valve opening period of the rotary valve is shortened, and the overlapping opening period between the rotary valve and the intake valve is reduced. Therefore, the amount of intake air in the combustion chamber can be reduced and the maximum pressure in the combustion chamber can be controlled to be substantially constant.

However, in the intake control system using a rotary valve, even when the rotary valve is closed, the intake air flows into the combustion chamber through the small gap between the rotary valve and the wall of the intake passage due to the influence of the intake negative pressure and, in a supercharged engine, the supercharging pressure. There is a concern that the amount of intake air will increase by an amount corresponding to the amount of leakage, and the maximum pressure in the combustion chamber will increase.

(Purpose of the invention) In view of the fact that the amount of intake air leakage increases as the engine speed decreases, this invention prevents the maximum pressure in the combustion chamber from increasing by correcting the intake air amount according to the engine speed. The aim is to improve engine reliability.

(Structure of the invention) The present invention has a communication hole that is arranged in the intake passage upstream of the intake valve and communicates between the upstream side and the downstream side of the arrangement position, and that is synchronized with the rotation of the engine and is arranged on the inner wall of the intake passage. a timing valve that rotates with a minute gap between the timing valve and the communication hole to communicate the upstream side and the downstream side at a predetermined rotational position; a transition means that transitions the opening period of the timing valve; The means is operated so that as the intake pressure upstream of the timing valve increases, the overlapping opening period between the timing valve and the intake valve decreases, thereby reducing the amount of intake air in the combustion chamber and suppressing the maximum pressure in the combustion chamber to a substantially constant value. The engine is equipped with a pressure adjusting means for detecting an engine rotational speed, a means for correcting an amount of reduction in intake air amount in a combustion chamber, and a control means for operating the correcting means based on the output of the detecting means. Therefore, the lower the engine speed, the greater the reduction rate of the intake air amount to prevent the maximum pressure in the combustion chamber from increasing.

(Example) Hereinafter, an example of the present invention will be described based on the drawings.

In the engine shown in FIG. 1, 1 is a four-cylinder engine body, 2 is a turbocharger in which a compressor wheel 5 and a turbine wheel 6 are interposed in an intake passage 3 and an exhaust passage 4, and 7 is an intake manifold 8. This is a timing valve (rotary valve) provided in the intake branch passage 9 that opens and closes this passage.

In each cylinder of the engine body 1, as shown in FIG. 2, a combustion chamber 13 is constituted by a piston 11 in the cylinder 10 and a cylinder head 12, and an intake port 14 and an exhaust port 15 opening into this combustion chamber 13 are They are opened and closed by an intake valve 16 and an exhaust valve 17, respectively. The timing valve 7 is
It is rotatably supported on the wall of the intake branch passage 9 on the upstream side of the intake valve 16 .

A drive shaft 18 connected to a crankshaft extends laterally from the engine body 1 as shown in FIG.
A valve shaft 19 connecting the timing valves 7 coaxially extends in the same direction. A valve drive shaft 21 is connected to this valve shaft 19 via a transition means 20 that shifts the opening period of the timing valve 7, and the drive shaft 18 on the engine body 1 side and the valve drive shaft 21 are connected to each other. 1/2 rotation of 18
It is linked via a first gear 22 and a second gear 23 that reduce the speed and transmit the speed to the valve drive shaft 21. Further, a timing gear 23 used for operating a distributor, a camshaft, an injection pump, etc. is meshed with the first gear 22.

The transition means 20 engages protrusions (not shown) provided at both ends of the adjustment piece 26 with helical splines 25, 25 formed at the ends of the valve shaft 19 and the valve drive shaft 21 with twists in opposite directions. By moving the adjusting piece 26 to the left, the valve shaft 19 is angularly displaced relative to the valve drive shaft 21 in the direction in which the timing valve 7 closes the intake branch passage 9 earlier, and the timing valve 7 is angularly displaced to the right. Conversely, during movement, the valve shaft 9 is angularly displaced so that the timing valve 7 closes the intake branch passage 9 late.

A pressure adjusting means 29 is connected to the adjusting piece 26 via an adjusting lever 28 that is swingably supported by a pin 27 to suppress the maximum pressure in the combustion chamber 13 to a substantially constant value. That is, the adjustment lever 28 is connected to a rod 33 of a piston 32 in a cylinder 31 via a link 30, and an intake pressure introduction pipe 34 for introducing intake pressure from the supercharger 2 is connected to the cylinder 31. , a pressure regulating spring 35 is provided that urges the piston 32 in a direction against the intake pressure. In other words, the higher the intake pressure, the more the pressure adjustment means 29 moves the piston 32 to the left, moves the adjustment piece 26 to the right, and angularly displaces the timing valve 7 in the earlier closing direction. The valve opening period that overlaps with the valve 16 is shortened to reduce the amount of air taken into the combustion chamber 13, thereby suppressing the maximum pressure in the combustion chamber 13 to a substantially constant value.

Then, the engine includes a rotation speed detection means 36 that detects the engine rotation speed, an intake pressure detection means 37 that detects the intake pressure downstream of the supercharger 2, that is, upstream of the timing valve 7, and the pressure adjustment a correction means 38 for correcting the amount of reduction in intake air amount by the means 29; a rotation speed detection means 36; and an intake pressure detection means 3.
The control means 39 receives the output of 7 and operates the correction means 38.

The correction means 38 includes a diaphragm device 41 connected to the adjustment lever 28 via a link 40.
, a vacuum pump 43 that applies operating pressure (negative pressure) to this diaphragm device 41 through an air passage 42 , and an electromagnetic three-way valve 45 that is interposed in the air passage 42 and has an atmosphere communication port 44 . We are prepared. In other words, this correction means 38 is the three-way valve 4
When the operating pressure acts on the diaphragm device 41 through the link 40 and the adjustment lever 28, the adjustment piece 26 is moved to the right through the timing valve 7.
This is to reduce the overlapping opening period of the intake valve 16 and the intake valve 16 to reduce the intake air amount.

Since the amount of intake air leakage when the timing valve is closed increases as the intake pressure increases and as the engine speed decreases, the control means 39 controls the control means 39 in the angular operation condition determined by the intake pressure and the engine speed. The intake pressure detection means 37 is equipped with a map in which a correction amount corresponding to the amount of intake air leakage is written.
In response to the output from the rotation speed detection means 36, a correction amount is calculated from the map, and a pulse signal corresponding to the correction amount is output to the correction means 38 to reduce the intake air amount.

In the above embodiment, intake air flows into the combustion chamber 13 of the engine from the supercharger 2 during a period in which the opening periods of the timing valve 7 and the intake valve 16 overlap, as shown in FIG. When the intake pressure downstream of the supercharger 2 and upstream of the timing valve 7 increases as the engine speed increases, the timing valve 7 is opened by the operation of the transition means 20 by the pressure adjustment means 29. The valve period is angularly displaced in the direction of becoming faster as shown by the chain line in Fig. 3, and the overlapping valve opening period described above is reduced, and the amount of intake air is reduced compared to the case without this angular displacement, thereby increasing the amount of intake air. is suppressed, and the maximum pressure in the combustion chamber 13 is suppressed to a substantially constant value.

As the intake pressure increases and the engine speed decreases, the amount of intake air leaking from the timing valve 7 increases. At this time, the control means 39
is the rotation speed detection means 36 and the intake pressure detection means 37
In response to the output from the correction means 38, a correction signal corresponding to the amount of intake air leakage is generated according to the operating state at that time.
By operating the transition means 20 and reducing the overlapping opening period of the timing valve 7 and the intake valve 16, the amount of intake air is reduced and the maximum pressure in the combustion chamber 13 is prevented from increasing.

In addition, in the above embodiment, in order to reduce the overlapping opening period of the timing valve and the intake valve, a method is adopted in which the opening period of the timing valve is advanced, but conversely, this valve opening period is delayed. You may also adopt the following method.

In addition, in the case of a diesel engine, the intake air amount reduction correction is achieved by providing an air bleed passage in the intake passage upstream or downstream of the timing valve, interposing a flow control valve in the passage, and receiving the output of the control means. Alternatively, a part of the intake air may be released.

Further, when a vacuum pump is used as the drive source of the correction means as in the above embodiment, the correction amount for reducing the intake air amount can be linearly performed by changing the rotational speed of the vacuum pump.

(Effects of the invention) According to the invention, in an engine that reduces the intake air amount according to the intake pressure, the reduction in the intake air amount is corrected so that the lower the engine speed becomes, the more the amount of reduction in the intake air amount increases. The increase in maximum pressure is more reliably prevented, and the maximum pressure is kept constant, improving engine reliability.

[Brief explanation of the drawing]

The drawings illustrate embodiments of the present invention, with Fig. 1 showing the overall configuration of the engine, Fig. 2 a vertical cross-sectional view of one cylinder of the engine, and Fig. 3 showing the opening period of the timing valve and intake valve. It is a graph diagram. 1...Engine body, 3...Intake passage, 13...
...combustion chamber, 16...intake valve, 20...transition means,
29...Pressure adjustment means, 36...Rotational speed detection means, 37...Intake pressure detection means, 38...Correction means, 39...Control means.

Claims (1)

[Scope of utility model registration request] It is arranged in the intake passage upstream of the intake valve, has a communication hole for communicating the upstream side and the downstream side of the arrangement position, synchronizes with engine rotation, and has a minute gap between it and the inner wall of the intake passage. a timing valve that rotates to connect the upstream side and the downstream side at a predetermined rotational position through the communication hole; a transition means that shifts the opening period of the timing valve; An engine equipped with a pressure regulating means that operates in such a way that the overlapping opening period of the timing valve and the intake valve decreases as the temperature rises, thereby reducing the amount of intake air in the combustion chamber and suppressing the maximum pressure in the combustion chamber to a substantially constant value. , a rotation speed detection means for detecting the engine rotation speed, a correction means for correcting the reduction amount of intake air amount by the pressure adjustment means, and a correction means for adjusting the correction means based on the output of the rotation intake detection means as the engine rotation speed is lower. 1. An intake air flow rate control device for an engine, comprising: control means for suppressing a rise in maximum pressure in a combustion chamber by operating in a direction that increases the amount of reduction in intake air amount.