JPS5893929A - Suction device for diesel engine - Google Patents

Abstract

PURPOSE:In a device for supercharging the inertia while utilizing the gas pole vibration in a resonant path provided in a suction system, to enable the inertia supercharge in the low speed region by constructing the resonace path with main and sub resonance paths and using each path while switching in accordance with the operating condition. CONSTITUTION:In the high and middle operating region of an engine 1, exchange valves 8a-8c are held at the position shown by the solid line by means of a controller. Consequently the air is supplied from an air cleaner 3 through a suction path 4 and main resonance paths 5a, 5b to each suction manifold 2a, 2b. While in the low speed operating region, said valves 8a-8c are exchanged to the position shown by the dashed line to flow the air into sub resonance paths 7a, 7b. since the resonant frequency of sub-resonance paths 7a, 7b is matched with the suction pulse frequency at the start of the engine in the cranking and idle circuit region, the start performance and the warming performance can be improved while increasing the suction volume efficiency and sesuring the output and torque of the engine.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an intake system for a diesel engine, and more specifically, the present invention relates to an intake system for a diesel engine, and more specifically, it is capable of increasing the intake volumetric efficiency at the time of starting or idling without impairing the intake volumetric efficiency in the high-speed rotation range. The present invention relates to an intake device that can perform inertial supercharging.

In order to reduce smoke emitted from a diesel engine and at the same time increase output and torque, it is effective to improve the intake volumetric efficiency of the engine.

As a supercharging means for improving the intake volume efficiency of an engine, there are a supercharger represented by an exhaust turbo supercharger ring,
Inertial supercharging devices in which a resonance passage is connected to an intake manifold are well known.

However, when supercharging is performed using a supercharger as in the former case, there are disadvantages in that the structure of the intake system becomes complicated, and at the same time, cost and weight increase. In addition, in the latter case where inertial supercharging is performed, although it has the advantage of simplifying the intake system and minimizing increases in cost and weight, the length and cross-sectional area of the resonance passage, etc. Since the matching rotation speed of the inertia effect is determined and changed depending on the There is a risk that the intake volumetric efficiency in the cranking rotation range or idling rotation range at the time of engine startup, which is far away from the above, will be extremely deteriorated, resulting in deterioration of engine startability, idling performance, etc.

The present invention has been made in view of the above, and while maintaining high intake volume efficiency in the high speed rotation range, it also increases the intake volume efficiency in the cranking rotation range or idling rotation range when starting the engine. The purpose is to improve the output performance, startability, etc. of The frequency is made to match the intake pulsation frequency in the engine high speed rotation range, and the resonance frequency of the sub-resonance passage is made to match the intake pulsation frequency in the cranking rotation range or idling rotation range at engine startup, and the engine operating condition is There is provided an intake system for a diesel engine, characterized in that a switching valve is provided for switching and closing only one of the main and sub-resonant passages as an ineffective passage based on the above.

The present invention will be explained in detail below based on an illustrated embodiment.

In the figure, the cylinder head of an in-line six-cylinder diesel engine 1 has first cylinders corresponding to the first to eighth cylinders.
By providing the intake manifold 2a and the second intake manifold 2b corresponding to the fourth to sixth cylinders, at least the cylinder strokes of the cylinders included in the same intake manifold will not overlap. I have to. The fuel injection order for an in-line six-cylinder diesel engine is generally set to 1-4-2-6-1-5, but 1-4-2-6-1-5.
The order may be 5-8-6-2-4.

In addition, an intake passage 4 extending from the secondary side of the air cleaner 3
and each of the intake manifolds 2a.

2b and 1.2b, respectively. Second main resonance passage 5a.

5b, and a branch passage 6 branched from the intake passage 4 and each intake manifold 2a, 2b. Second sub-resonant passage 7a.

7b, and then connect the intake passage 4 and the branch passage 6.
Switching valves 8a, 8b, and 8c are provided at the branch points between the resonant passages and the intake manifolds, respectively. 9 is an exhaust manifold.

Here, the length and cross-sectional area of the main resonance passages 5a, 5b are determined depending on these specifications. , 2b so as to match the frequency of the intake pulsation occurring in the air. And the other resonance passage,
In other words, the length and cross-sectional area of the sub-resonant passages 7a, 7b are determined by these specifications. When the resonance frequency of the air column in b is in the cranking rotation range at the time of starting the engine 1 or in the idling rotation range, the intake marfold 2a, 2
The frequency is set to match the frequency of the intake pulsation that occurs within b. In addition, each of the switching valves 8a, 8b, and 8c is connected to a branch passage 6 in a normal rotation range as shown by a solid line in FIG.
For example, when the engine speed is slightly lower than the idle speed, the controller as shown in the figure In response to this command, switching is performed as shown by the two-dot chain line in FIG. 1 to close the main resonance passages 5a and 5b.

In the above configuration, when the engine 1 is operated, this operating information is supplied to a controller (not shown). and,
When the engine 1 is operated in a medium-high speed range, the controller holds the switching valves 8a, 8b, and 8c in the positions shown by the solid lines, so that the air cleaner 8 and the intake manifold are connected to each other via the main resonance passages 5a, 5)). 2a and 2b are connected. Moreover, the resonance frequency of the main resonance passages 5a and 5b is
Since it matches the intake pulsation frequency in the high-speed rotation range, the intake volume efficiency in the high-speed rotation range is high as before, suppressing the emission of smoke and harmful exhaust components, and
Output power and torque are improved.

Also, when the engine 1 is operating in a region lower than the set rotation speed, each switching valve 8a, 8b,
8c operate as indicated by two-dot chain lines to close the main resonance passages 5a, 5b, and communicate the air cleaner 3 with the intake manifolds 2a, 2b via the cut resonance passages 7a, 7b. At this time, since the resonance frequency of the sub-resonant passages 7a and 7b is made to match the intake pulsation frequency in the cranking rotation range or idling rotation range when starting the engine, the main resonance passage is at least in the low rotation range below the set rotation speed. 5a, 5b
The intake volumetric efficiency can be improved compared to the case where the

Therefore, even in such a low rotation range, the IC in the exhaust gas,
This means that Co and the like can be reduced.

Similarly, the intake air volume efficiency at the time of starting and idling the engine 1 is also improved, so that the startability and warm-up performance of the engine 1 are improved. In particular, if the resonance frequency of the auxiliary resonance passages 7a and 7b is made to match the intake pulsation frequency in the cranking rotation range when starting the engine, the intake volume efficiency during cranking can be greatly improved and the actual compression ratio can be increased. Since it can be made larger, the cold startability of the engine is improved. On the other hand, if the sub-resonant passages 7a and 7b are similarly matched to the idle rotation range, the temperature of the combustion chamber during idle can be increased, so white smoke, HC, Co, etc. that are observed during warm-up can be significantly reduced. . still,
Regardless of whether the matching rotation speed of the sub resonance passages 7a, 7b is set in the cranking rotation range or the idling rotation range, the intake volume efficiency in the other region can also be increased, so the sub resonance passages 7a and 7b can be set in accordance with the characteristics of the engine. The matching rotational speed of the resonant passage may be set to either one or to a midpoint between the two.

That is, when only the main resonance passages 5a and 5b are provided, the second
As shown by the two-dot chain line in the figure, the intake volumetric efficiency takes effect in the low-speed range, but as shown by the one-dot chain line in the figure, cranking (B) is reproduced or the matching rotation speed is set in or near the idle rotation range. Since a switching valve is provided to switch between the main and sub-resonant passages 7a and 7b and the main and sub-resonant passages, the intake volumetric efficiency can normally be improved in any rotational range as shown by the solid line in FIG.

In the embodiment, the switching valve is operated to switch only in response to the engine speed, but other factors such as engine temperature, outside air temperature, and temperature can also be switched. It can also be used as a cumulative control cost for the valves to obtain the optimal intake volume efficiency for the operating conditions of the engine. Further, in the embodiment, a switching valve is provided at the branching part and the merging part of each passage, but either one may be omitted, and the specific structure of the switching valve is arbitrary.

As explained above, according to the present invention, the desired inertial supercharging is performed not only in the high-speed rotation range where output is important, but also in the cranking rotation range and the idling rotation range. It is possible to improve starting performance and warm-up performance while ensuring the maximum output and torque of the tower gate.

[Brief explanation of drawings]

FIG. 1 is a block diagram of an embodiment of the present invention, and FIG. 2-9 is a diagram showing the relationship between the number of engine operations and the intake volumetric efficiency. 1...Diesel engine 2a, 2b...
Intake manifold 3...air cleaner
4...Intake passages 5a, 5b...Main resonance passages
6... Branch passages 7a, 7b... Sub-resonance passage 8a
, 8b, 8c...Switching valve 0 Applicant Hino Motors Co., Ltd. 1n-

Claims (1)

[Claims] In a diesel engine in which a resonant passage is provided in the intake system and inertial supercharging is performed using the vibration of an air column generated within the passage, the resonant passage is connected in parallel to the main resonant passage and the passage. The resonant frequency of the main resonant passage is made to match the intake pulsation frequency in the high-speed engine rotation range, and the resonant frequency of the sub-resonance passage is matched in the cranking rotation range or idling rotation range when starting the engine. An intake system for a diesel engine, characterized in that it is provided with a switching valve that matches the intake pulsation frequency of the engine and switches and closes only one of the main and sub-resonant passages as an invalid passage based on the operating state of the engine.