JPS6332123A - Intake device for direct injection type diesel engine - Google Patents

Abstract

PURPOSE:To reduce the formation of smoke by installing an intake timing controller which is opened and closed in synchronization with the revolution of an engine onto each intake port of a helical port and a tangential port and controlling the opening/closing timing according to the operation state. CONSTITUTION:A helical intake port 3 and a tangential intake port 5 are installed into each cylinder of a direct injection type Diesel engine. An intake controller which is revolved by a pulley driven in interlocking with a crankshaft is installed onto the upstream side of each intake port. A hole 9b having an inclined edge is formed onto the helical intake port 3, and a hole 9b having a straightline edge is formed onto the tangential intake port 5. A control gear position control means 21 and a release member position control means 20 are controlled by the signal of an intake timing control device 22, and the whole timing is controlled by a control means 21, and only the timing of the port 3 can be controlled by the control means 20.

Description

DETAILED DESCRIPTION OF THE INVENTION Industrial Application 111F The present invention relates to an intake system for a direct-injection day cell engine in which a helical intake port and a Kunjential intake port are provided for one cylinder. The present invention relates to an intake system for a direct injection diesel engine having means for controlling the intake timing of a helical intake port and a Kunsential intake port depending on the operating state of the engine.

In order to improve performance such as fuel efficiency and output in prior art direct injection diesel engines, it is necessary to promote the dispersion of the fuel injected into the combustion chamber so that it mixes well with the air, and to reduce the amount of air taken into the combustion chamber. It is necessary to increase the filling efficiency. In order to improve the dispersion of fuel in the combustion chamber, it is preferable to create a swirl in the intake air drawn into the combustion chamber, and for this reason, various improvements have been made to the shape of the intake port. Typical examples are helical intake ports and tangential intake ports. The helical intake port has a helical shape at the downstream end of the intake port of the combustion chamber, and when the intake air passes through this part, it creates a swirl in the intake air, and the stool improves the flow of fuel into the combustion chamber. It is an attempt to split the limbs. However, since the helical intake port has a large intake loss of intake air, the amount of air taken into the combustion chamber tends to decrease, and the amount of intake air filled tends to decrease. On the other hand, the tangential intake port has a smaller intake loss of intake air than the helical intake port, but has the disadvantage that it is difficult to generate a sufficiently strong swirl.

Therefore, by providing these two intake ports in one cylinder,
Attempts have been made to draw intake air into the combustion chamber from one or both of them at an appropriate timing depending on the operating condition of the engine, to generate a swirl of desired strength and to ensure a sufficient amount of intake air filling. . For example, Japanese Patent Application Laid-Open No. 58-135323 discloses that a helical intake port and a tangential intake port are provided in communication with each other in the combustion chamber of a diesel engine, and an intake valve provided in the helical intake port and a tangential intake port are provided in communication with each other. We have proposed an intake system for a direct injection diesel engine that controls the opening timing of the intake valve according to the operating state of the engine. In this intake system, air is taken only from the helical intake port in the low rotation range, and the opening timing of the intake valve of the helical intake port is delayed so that the piston is located near the midway between top dead center and bottom dead center. By opening the valve at the appropriate time to generate a strong swirl, a strong swirl is generated in the combustion chamber, promoting fuel dispersion, and on the other hand,
In the high rotation range, the intake valve of the tangential intake port is controlled to open early and close late, allowing more intake air to flow through the tangential intake port with less loss of intake air, increasing the amount of intake air filling. ing.

Problems to be Solved by the Invention However, in this device, the timing of intake air from the helical intake port and the tangential intake port is controlled only by the engine speed, and is not controlled by the engine load at all. Therefore, there are operating regions where it is inappropriate to control with this device, and it cannot be said that the performance of the direct injection diesel engine can be sufficiently improved, especially in the low-speed operating range. I couldn't move up one level.

OBJECTS OF THE INVENTION An object of the present invention is to provide an intake system for a direct injection diesel engine that is capable of producing a swirl of strength suitable for various operating conditions and a sufficient amount of intake air filling with a simple configuration. It is something to do.

With a simple configuration, the present invention makes it possible to improve the ignition performance at low loads, especially in the low rotation operating range, and to increase the intake light 1ffi at high loads, thereby reducing the amount of smoke generated. The object of the present invention is to provide an intake system for a direct injection diesel engine.

Structure of the Invention The object of the present invention is to provide a helical intake port intake means that is provided in a helical intake passage connected to a helical intake port and whose intake timing is controlled according to the engine speed; A tangential intake port intake means is provided in the tangential intake passage and the intake timing is controlled according to the engine load, and the piston in the combustion chamber starts descending from top dead center at the start of the intake stroke. The intake timing of the helical intake board intake means has a large delay at low rotation speeds,
The timing of the intake of the helical intake port intake means and the tangential intake port intake means is controlled so that the delay becomes smaller as the rotation speed increases, and the intake timing of the helical intake port intake means and the tangential intake port intake means are controlled such that, at low rotation speeds and low loads, The timing of intake from the helical intake port is earlier than the timing of intake from the helical intake port, and at low speeds and high loads, the timing of intake from the helical intake port is controlled earlier than the timing of intake from the Kunstial intake port. This is achieved by providing control means.

According to the present invention, by configuring the intake system of the direct injection diesel engine in this way, in the low rotation and low load range,
First, air is taken into the combustion chamber through the tangential intake port, and then through the helical intake port. This makes it possible to reduce intake resistance and ensure a sufficient amount of intake air. , the intake air from the Kunjential intake port flows into the combustion chamber, and after the negative pressure in the combustion chamber becomes small, it is taken in from the helical intake port, which makes it possible to lower the swirl.
It is possible to greatly improve ignition performance, and on the other hand, in low rotation and high load ranges, air is first taken in from the helical intake port, and then from the tangential intake port, which creates a sufficiently strong swirl. In addition, since the intake air is delayed from the start of the intake stroke, the intake inertia effect makes it possible to secure a sufficient amount of intake air, which can significantly reduce the occurrence of smoke. .

In a preferred embodiment of the present invention, on the upstream side of the intake valve in the helical intake passage connected to the helical intake port,
Helical intake control valve means are also provided upstream of the intake valves in the tangential intake passages leading to the tangential intake ports, and tangential intake control valve means are respectively provided. Each intake timing is controlled by controlling the valve opening timing. By adopting such a configuration, the opening timing of the intake valves of the helical intake port and the tangential intake port can be kept constant.
The simple configuration makes it possible to control the timing of intake from each intake port as desired.

EXAMPLES Hereinafter, examples of the present invention will be described in detail based on the accompanying drawings.

FIG. 1 is a schematic plan view of an intake system for a direct injection diesel engine showing one embodiment of the present invention.

In FIG. 1, an intake system according to an embodiment of the present invention has a helical intake port 3 connected to a helical intake passage 2 and a tangential intake passage 4 connected to each combustion chamber 1 of a direct injection enclosed cylinder diesel engine. A tangential intake port 5 is provided, with each helical intake port 3 at the downstream end of each helical intake passage 2 formed in a helical shape, and the tangential intake port 5 at the downstream end of each tangential intake passage 4. Each of them is provided with an intake valve (not shown).

The helical intake passage 2 is connected on its upstream side to a rotary type helical intake control valve means 6 whose opening timing is controlled according to the engine speed, and the tangential intake passage 4 is connected on its upstream side. , is connected to a rotary type tangential intake control valve means 7 whose opening timing is controlled according to the engine load, and controls the opening timing of the helical intake control valve means 6 and the tangential intake control valve means 7. By doing so, the intake timings of the helical intake port 3 and the tangential intake port 5 are respectively controlled.

FIG. 2 shows the details of the structure of the helical intake control valve means 6 and the tangential intake control valve means 7 used in this embodiment. Reference numeral 7 is composed of a rotary valve 10 having a double structure consisting of an outer rotor 8 and an inner rotor 9.

The outer rotor 8 and the inner rotor 9 are rotated by a pulley 11 that rotates in synchronization with a crankshaft (not shown).
It is rotatably engaged with pulley 11. That is, a groove is cut on the outer surface of one end 12 of the outer rotor 8 at a predetermined angle, and on the other hand, a groove is cut on the outer surface of one end 13 of the shaft of the pulley 11 at a different angle. , By engaging the control gear 14 with these grooves, the outer rotor 8 is connected to the pulley 11.
It is configured so that it can be physically rotated.

Moreover, the inner rotor 9 is circumferentially connected to the pulley 11 by engagement between a groove provided in the axial direction on the outer surface of the one end portion 15 and a groove provided in the axial direction on the inner surface of the shaft of the pulley 11. It is configured to be fixed in the direction and rotated integrally with the pulley 11. Inner rotor 9
An intake passage 16 is provided inside, and intake air is fed into the intake passage 16. The circumferential surface of the inner rotor 9 is provided with a plurality of holes 9a, 9b in the axial direction that communicate with the intake passage 16, and the circumferential surface of the outer rotor 8 is also provided with a plurality of holes 8a, 9b in the axial direction. 8b is provided. The holes 9a, 9b provided on the circumferential surface of the inner rotor 9 and the holes 8a, 8b provided on the circumferential surface of the outer rotor 8 are located at positions where at least a portion of their openings overlap each other, and The intake passage 16 is provided at a position where the intake passage 16 and the helical intake passage 2 or the tangential intake passage 4 can communicate with each other when the outer rotor 8 and the inner rotor 9 rotate as the outer rotor 8 and the inner rotor 9 rotate. A hole 3a provided in the outer rotor 8.

The position of 8b is configured so that it can be changed in the circumferential direction with respect to the pulley 11 depending on the engine speed. That is, since the grooves on the outer surface of the one end 12 of the outer rotor 8 and the grooves on the outer surface of the one end 13 of the shaft of the boot Ul 1 are cut at different angles, the control gear 14 By moving the outer rotor 8 in the axial direction, the relative positions of the holes 8a and 8b provided in the circumferential surface of the outer rotor 8 with respect to the pulley 11 in the circumferential direction can be changed. Further, the positions of the holes 9a and 9b provided on the circumferential surface of the inner rotor 9 are configured to be changeable in the axial direction with respect to the pulley 11 depending on the engine load. That is, the inner rotor 9 has one end 15 biased in the axial direction by a spring 17, and a stopper 18 provided on the outer peripheral surface near the other end.
The axial position can be set by a release member 19 that engages with the release member 19 and resists the biasing force of the spring 17, and the release member 19 is moved in the axial direction by a release member position control means 20. This allows the inner rotor 9 to be set at a desired axial position. Among the holes 9a and 9b on the circumferential surface of the inner rotor 9, the hole 9b on the helical intake passage 2 side is provided so that its circumferential end is oblique to the axis of the inner rotor 9. When the release member 19 is moved in the axial direction, the circumference of the portion where the hole 9b on the circumferential surface of the inner rotor 9 and the hole 8b on the circumferential surface of the outer rotor 8 overlap, that is, the portion through which intake air can pass, relative to the pulley 11 The relative position in the direction is configured to be changed.

In addition, in response to detection signals detected by various detection means (not shown) that detect engine speed, intake pipe internal pressure, engine cooling water temperature, atmospheric pressure, etc., the piston in the combustion chamber is detected at the start of the intake stroke. The opening timing of the helical intake control valve means 6 with respect to the point at which descent starts from top dead center is controlled so that the delay is large at low rotations and becomes smaller as the rotation increases, and at low loads. In contrast, when the load is high, the opening timing of the tangential intake control valve means 7 is delayed, and in the low rotation and low load range, the tangential intake control valve means 7 is opened earlier than the helical intake control valve means 6, and when In the load range, the helical intake control valve means 6 and the tangential intake control valve means 7 are opened so that the helical intake control valve means 6 is opened earlier than the tangential intake control valve means 7.
The control signal for controlling the valve opening timing is sent to control gear 1.
a control gear position control means 21 that drives a lever (not shown) that controls the position of the release member 1;
An intake timing control device 22 composed of, for example, a microcomputer is provided, which outputs an output to a release member position control means 20 that controls the position of the release member 9 .

The diesel engine intake system of this embodiment configured as described above operates as follows.

The intake timing control device 22 receives detection signals such as engine rotation speed, intake pipe internal pressure, engine cooling water temperature, and atmospheric pressure from each of the detection means, and calculates a control signal based on the detected value of the engine rotation speed. The control signal is outputted to the control gear position control means 21, and a control signal obtained by calculation based on the detected value of the intake pipe internal pressure is outputted to the release member position control means. The control gear position control means 21, which receives a control signal from the intake timing control device 22, adjusts the opening timing of the helical intake control valve means 6 relative to the start point of the intake stroke according to the input control signal.
The position of the control gear 14 is adjusted by driving the lever so that the delay is large at low rotations and becomes smaller as the rotation becomes higher. Furthermore, the release member position control means 20 that receives a control signal from the intake timing control device 22 delays the opening timing of the tangential intake control valve means 7 at high loads compared to low loads, and in the low rotation and low load range, The tangential intake control valve means 7 opens earlier than the helical intake control valve means 6, and the helical intake control valve means 6 opens earlier than the tangential intake control valve means 7 in a low rotation and high load range.
By moving the release member 19, the relative positional relationship between the holes 3a, 3b provided in the outer rotor 8 and the holes 9a, 9b provided in the inner rotor 9 is controlled.

Since misfires are likely to occur when the engine is cold, the swirl should be weakened at high altitudes at low and medium loads in the low and medium speed ranges, and vice versa at high loads in the low and medium speed ranges. If each correction is made in the direction of increasing the swirl, it will be more effective to improve ignition performance and reduce smoke.

The intake system of the direct injection diesel engine according to this embodiment is as follows:
With the above structure, in the low rotation and low load operating range, first, the tangential intake control valve means 7 opens, air is taken in from the tangential intake port 5, and then the helical intake control valve means 6 opens. Since it is opened and air is taken in from the helical intake port 3, the intake resistance of air is small and a sufficient amount of air can be secured. In addition, after the intake air from the tangential intake port 5 flows into the combustion chamber 1 and the negative pressure inside the combustion chamber 1 becomes small, the intake air flows from the helical intake port 3, so that the swirl can be lowered. . In this way, sufficient intake air filling amount is obtained and swirl is kept low, so ignitability is significantly improved.

In addition, in the low rotation and high load operating range, first, the helical intake control valve means 6 opens after the start of the intake stroke, and air is taken in from the helical intake port 3. After the negative pressure in the helical intake passage 2 and the combustion chamber 1 becomes sufficiently high, the helical intake control valve means 6 opens, and the dynamic pressure accompanying the increase in intake flow rate and the internal helical intake passage 2 are reduced. Due to the generated intake inertia, the pressure inside the helical intake passage 2 changes to the positive side just before the piston reaches the bottom dead center, so that the intake air is forced into the helical intake passage 2 into the combustion chamber 1. A supercharging effect occurs, and a sufficiently large amount of intake air can be obtained. Further, since the intake air is drawn into the combustion chamber 1 at a high flow velocity through the helical intake port 3, a strong swirl can be generated, and the fuel and intake air can be sufficiently mixed. in this way,
Since a sufficient amount of intake air can be secured and fuel and intake air can be sufficiently mixed, it is possible to significantly reduce the occurrence of smoke.

The present invention is not limited to the above-mentioned examples, but various modifications can be made within the scope of the invention described in the claims, and these are also included within the scope of the present invention. , Needless to say.

For example, in the above embodiment, rotary type valves are used as the helical intake control valve means 6 and the tangential intake control valve means 7, but they are not limited to these types, and other types may be used. type valve means may also be used.

Effects of the Invention According to the present invention, it is possible to significantly improve the ignitability in the low-speed, low-load operating range, increase the amount of intake air filling in the low-speed, high-load operating range, and reduce smoke generation. This makes it possible to significantly reduce the

[Brief explanation of the drawing]

FIG. 1 is a schematic plan view of an intake system for a direct injection diesel engine showing one embodiment of the present invention. FIG. 2 is a drawing showing the structure of the intake control valve means used in one embodiment of the present invention. ■...Combustion chamber, 2...Helical intake passage, 3...Helical intake port, 4...Tangential intake passage, 5...Tangential intake port, 6...Helical intake control valve means , 7... Tangential intake control valve means, 8... Arakuro rotor, 8a, 8b... Holes on the circumferential surface of the Arakuro rotor, 9...
Inner rotor, 9a, 9b... Holes on the circumferential surface of the inner rotor, 10...
・Rotary valve, 1 l ・ ・ ・ Pulley, 1411
1 control gear, 16... intake passage, 17... spring, 18... stopper, 19... release member, 20... release member position control means, 21... control gear position control means, 22...Intake timing control device.

Claims (1)

[Claims] In an intake system for a direct injection diesel engine in which a helical intake port and a tangential intake port are provided for one cylinder, the intake port is provided in a helical intake passage connected to the helical intake port, and the intake timing is adjusted according to the engine speed. a helical intake port intake means that is controlled; a tangential intake port intake means that is provided in a tangential intake passage connected to the tangential intake port and whose intake timing is controlled according to the engine load; The intake timing of the helical intake port intake means with respect to the starting point is controlled so that the delay is large at low rotation speeds and becomes smaller as the rotation speeds become higher. The intake timing of the port intake means is set such that at low speeds and low loads, the timing of intake air from the tangential intake port is earlier than the timing of intake air from the helical intake port, and at low speeds and high loads, the timing of intake air from the tangential intake port is earlier than the timing of intake air from the helical intake port at low speeds and high loads. An intake system for a direct injection diesel engine, comprising an intake timing control means for controlling the timing of intake air from a port earlier than the timing of intake air from a tangential intake port.