JPS61277815A - Intake apparatus of direct injection type diesel engine - Google Patents

Abstract

PURPOSE:To certainly control swirl and the intake quantity by installing throttle valves for controlling the quantity of the intake with passes through the ports, in an engine equipped with two independent ports such as helical port and direct port in each cylinder. CONSTITUTION:A helical port 4 and a direct port 3 are formed onto one cylinder, and throttle valves 17 and 18 are arranged into the independent suction passages 14 and 15 connected to the ports. Each throttle valve is opened and closed according to the engine revolution speed and the engine load. In low load and at low revolution speed, the throttle valve 18 on the direct port 3 side is closed, and a strong swirl is formed, and a direct port side throttle valve 17 is opened according to the increase of the load and revolution speed, and thus arbitrary control is permitted.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an intake system for a direct injection diesel engine.

BACKGROUND OF THE INVENTION Conventionally, some direct-injection diesel engines employ a helical port whose inner peripheral surface is formed in a spiral shape as an intake port. This system swirls the air taken into the cylinder in a helical port, generates a swirling flow inside the cylinder due to its inertia, and injects fuel into the swirling flow that remains until the end of the compression stroke, thereby combining compressed air and fuel. This is to ensure proper mixing of the ingredients.

Furthermore, as described in Japanese Utility Model Application Publication No. 60-58827, there is also a device that uses a helical port 1- and a direct port with a smooth inner circumferential surface. This is because during high-speed operation, the amount of intake air from the helical port decreases due to the increase in passage resistance of the helical port, so the amount of intake air from the direct port is increased in accordance with this decrease.
This is to ensure a sufficient amount of intake air at all times and to increase the proportion of non-swirling flow sucked in from the direct port to reduce the strength of the swirl flow (swirl ratio) and make the swirl ratio suitable for high-speed operation. be.

Problems to be Solved by the Invention The optimal swirling flow strength (swirl ratio) for an engine varies greatly depending on the engine speed and load; it is large at low speeds, small at high speeds, and small at low loads. is small and large under high load. For this reason, when only helical ports are employed, the amount of intake air becomes insufficient due to the increase in passage resistance at high speeds as described above, resulting in high-speed deterioration of engine performance. Furthermore, since swirl cannot be adjusted, the swirl ratio becomes inappropriate outside the preset rotational speed and load ranges, resulting in poor engine performance.

The method described in Japanese Utility Model Application Publication No. 60-58827 has the following points: a sufficient amount of intake air is always ensured, and during high-speed operation, the amount of intake air from the helical port is reduced and the amount of intake air from the direct port is reduced. This is advantageous in that the swirl ratio decreases as a result of the increase, resulting in a swirl ratio suitable for high-speed operation. However, it is not possible to adjust the swirl ratio appropriately according to changes in engine speed, and
It is not possible to adjust swirl according to changes in engine load.

The present invention was made in view of these points.

An object of the present invention is to obtain an intake system for a direct injection diesel engine that can obtain a sufficient amount of intake air and an optimal swirl ratio over the entire range from low speed to high speed and from low load to high load.

Means for Solving the Problem A direct port 3 and a helical port 4 communicating with one cylinder 2 are formed in the cylinder head 1, and an intake manifold 13 communicating with these direct ports 3 and helical port 4 is formed in the cylinder head. Connect to 1. An intake air passage 15 that communicates with the direct port 3 and an intake air passage 14 that communicates with the hemi-cal port 4 are formed in the intake manifold 13. Throttle valves 17 and 18 are provided to control the amount of intake air.

Operation Air is sucked into the cylinder 2 from the direct port 3 and the helical port 4, the air sucked from the helical port 4 is swirled within the helical port 4, and a swirling flow is generated within the cylinder 2 due to inertia. Fuel is injected into the swirling flow that remains until the end of the compression stroke to achieve proper mixing of compressed air and fuel. The optimum swirl ratio in a direct injection diesel engine differs depending on the rotation speed of the engine 21 and the load. Obtain a good swirl ratio. Also.

Even when the amount of intake air from the helical port 4 decreases due to an increase in passage resistance during high-speed operation, the decrease is compensated for by suction from the direct port 3, and a sufficient amount of intake air is always ensured.

Example An embodiment of the present invention will be described based on the drawings.

A direct port 3, a helical port 4, and an exhaust boat 5 are formed in the cylinder head 1 in communication with one cylinder 2. The direct port 3 has a smooth inner peripheral surface, and the helical port 4 has a spiral inner peripheral surface. The helical port 4 and the direct port 3 are arranged in two stages, upper and lower, as shown in FIG. As shown in , they are arranged in the front-rear direction along the peripheral wall of the cylinder head 2 . Further, the cylinder head l includes a fuel injection nozzle mounting portion 8.
, a cooling water passage 9, and a valve guide section 10 that holds a valve (not shown). A boss portion 12 is formed for tightening and fixing the cylinder head 1 to the cylinder block 11.

An intake manifold 13 is connected to the cylinder head 1, and within the intake manifold 13, an intake air passage 14 communicating with the helical port 4 and an intake air passage 15 communicating with the direct port 3 are connected to a partition wall 16. It is partitioned and formed.

The intake air passage 14. ．． Inside 15 is a throttle valve 17.
．． A lever 19.20 is connected to each throttle valve 17, 18 for rotating the throttle valve 17.18.

Next, as shown in FIG. 4, a rotation speed sensor 22. which detects the rotation speed of the engine 21. A load sensor 23 that detects the load of the engine 21 and these rotation speed sensors 22
and a control unit 2 that inputs detection signals from the load sensor 23 and the load sensor 23.
4 is provided.

Furthermore, the throttle valve 17.1 is controlled via the lever 19.20 by a control signal output from the control section 24.
An actuator 25° 26 for rotating the 8 is provided. Note that the exhaust boat 5 is connected to the cylinder head 1.
The exhaust manifold 27 is connected to the exhaust manifold 27 .

In such a configuration, the piston 28 during the suction stroke
falls and the inside of cylinder 2 becomes negative pressure, and the intake valve (
(not shown) opens, and air is sucked into the cylinder 2 from the die reflex 1 to the boat 3 and the helical port 4. At this time, the air taken in from the helical ports 1 to 4 swirls within the helical port 4, and a swirling flow in the direction of arrow a shown in FIGS. 5 and 6 is generated within the cylinder 2 due to inertia. Then, fuel is injected from the fuel injection nozzle 29 into the swirling flow that remains until the end of the compression stroke, and the compressed air and fuel are mixed.

Here, the optimum swirl ratio for achieving proper mixing changes depending on the rotation speed of the engine 21 and the size of the load, and is large at low speeds and small at high speeds, and small and high at low loads. The load is large.

Therefore, the detection signal from the rotation speed sensor 22 that detected the rotation speed of the engine 2°1 and the detection signal from the load sensor 23 that detected the load of the engine 21 are input to the control unit 24, and control is performed based on the input detection signals. Output a signal.

This control signal drives the actuators 25 y 26 and the throttle valve 17.1 via the lever 19.20.
Rotate 8. As a result, the ratio and flow velocity of the swirling flow from the helical port 4 and the non-swirling flow from the direct port 3 are changed, the swirl ratio is controlled, and the engine 2
The optimum swirl ratio according to the rotation speed and load of 1 can be obtained. When the optimum swirl ratio is obtained, the mixture 31 of the fuel injected into the combustion chamber 30 at the top of the piston 28 at the end of the compression stroke becomes uniform, as shown in FIG. Combustion after ignition is performed well, improving fuel consumption and reducing exhaust gas concentration. Furthermore, an easy-to-use engine with constant shaft torque can be obtained. FIG. 6 shows a state in which the rotational speed of the engine 21 is increased without adjusting the opening degrees of the throttle valves 17 and 18 in comparison with FIG. 5.

As the rotational speed increases, the swirling flow velocity increases and the fuel injection time becomes longer, so that a portion of the mixing portion 31 of fuel and compressed air overlaps, resulting in a fuel-excess portion 32. When this fuel-excessive portion 32 is ignited, a large amount of soot is generated, the exhaust gas concentration increases, and the fuel consumption rate decreases.

In addition, when the flow rate of intake air increases, the passage resistance of the helical port 4 increases, and the amount of intake air from the helical port 4 decreases, but this decrease is always compensated for by the direct port 3, which has less passage resistance. A sufficient amount of intake air is ensured, and rapid deterioration due to a decrease in the amount of intake air is prevented.

Effects of the Invention As described above, the present invention forms an intake air passage communicating with the direct port and an intake air passage communicating with the helical port in the intake manifold, and provides airflow in each intake air passage depending on the engine speed and load. By providing a throttle valve to control the amount of intake air according to the engine speed and load, the ratio and flow velocity of the swirling flow taken in from the helical port and the non-swirling flow taken in from the direct port are adjusted. It is possible to obtain the optimum swirl ratio, and if the amount of intake air from the helical port 1 decreases due to an increase in the flow resistance of one passage, the reduced amount is compensated for from the direct port to always maintain a sufficient amount of intake air. Therefore, improvement of intake efficiency and fuel consumption rate can be ensured over a wide range from low speed rotation range to high speed rotation range and from low load range to high load range.

This has effects such as reducing exhaust gas concentration and equalizing shaft torque.

[Brief explanation of the drawing]

The drawings show one embodiment of the present invention, and FIG. 1 is a longitudinal sectional side view, FIG. 2 is a sectional view taken along the line A-A in FIG. 1, and FIG. 3 is a sectional view taken along the line B-B in FIG. 1. , Fig. 4 is a control system diagram for the intake air amount, Fig. 5 is an explanatory diagram showing the state of mixture formation under an optimal swirl ratio, and Fig. 6 is an illustration showing the state of mixture formation under an inappropriate swirl ratio. Figure 7 is an explanatory diagram showing the state of formation, and shows the intake efficiency, fuel consumption rate, shaft torque, and exhaust gas concentration with respect to changes in engine rotational speed for a conventional example with only helical ports (dashed line) and this example (solid line). This is a graph showing a comparison. 1... cylinder head, 2.2 cylinder, 3...
Direct port, 4...Helical port, 13...
・Intake manifold, 14.15... Intake air passage, 1
7゜18...Throttle valve, 21...Engine start request Person Ishikawajima Shibaura Machinery Co., Ltd., %Zkon

Claims (1)

[Claims] A cylinder head is formed with a direct port and a helical port that communicate with one cylinder, an intake manifold that communicates with the direct port and the helical port is connected to the cylinder head, and the intake manifold communicates with the direct port. and an intake air passage communicating with the helical port, and a throttle valve is provided in the intake air passage for controlling the amount of intake air according to engine rotation speed and engine load. Intake system for direct injection diesel engines.