JPH0291419A - Suction system for internal combustion engine - Google Patents

Abstract

PURPOSE:To make it possible to keep high volumetric efficiency in a whole engine operation range by opening and closing a plurality of passages connecting the main air flowing section of a suction pipe to a resonant box or pipe by use of solenoid valves depending upon the variety of running conditions. CONSTITUTION:A controller 24 controls the opening of solenoid valves 11 through 13 based on the running conditions such as engine speed detected by a engine speed detector and input therein. The solenoid valve 11 opens while an engine is running at a speed of around N in a low speed range, and the other valves 12 and 13 are closed. This makes a resonant box 7 start to resonate when engine speed reaches around N to increase the pressure vibration in the resonant box 7 resulting in the enhancement of volumetric efficiency due to the resonant effect of the whole of a suction system. In order to more enhance the resonant effect, a resonant pipe junction section I is provided at the position where the characteristic frequency of the down stream side lower than the junction section I is approximately synchronized with an engine speed of N. In the same way, when engine speed is increased so as to reach N or around N, the solenoid valve 12 or 13 is opened, and the other valve is closed. Therefore, suction vibration can be utilized in the whole running range.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an intake system for an internal combustion engine, particularly for a four-stroke internal combustion engine.

[Conventional technology]

An example of a conventional intake system for a four-stroke internal combustion engine is shown in FIG.

In the figure, 1 is an intake manifold, 2 is a surge tank, 3 is a throttle valve, 4 is a throttle valve, 5 is an air intake valve, and 6 is an air cleaner. The suction end (A end in the figure) of the intake system is open to the atmosphere, and the outlet end (A end in the figure) is open to the atmosphere.
The B end) is communicated with the cylinder through a passage in the cylinder head, and is opened and closed by an intake valve (not shown).

The operation of the conventional device will be explained. During the intake stroke, air is sucked in from the A end due to the negative pressure generated by the downward movement of the piston. The sucked air passes through the air cleaner 6, the air intake valve 5, the throttle valve 4, the throttle valve 3, the surge tank 2, and the intake manifold 1, enters the cylinder head passage from the B end, passes through the intake valve section, and enters the cylinder. is filled with. At this time, the amount of air inflow is adjusted by changing the opening degree of the throttle valve 4 depending on the operating conditions of the engine.

However, air is not inhaled as a steady flow, but pulsates in the intake pipe because the negative pressure generated in the cylinder is repeatedly reflected at the volume part, the open end to the atmosphere, and the valve part, resulting in an unsteady flow. Inhaled. If the intake amount of air increases, that is, the volumetric efficiency increases, more fuel can be supplied and the output can be increased. For this reason, the length, diameter, and volume of the intake system are determined to make the most effective use of pulsation so as to inhale air most efficiently.

[Problem to be solved by the invention]

In the conventional example, the length and diameter of the entire intake system from the intake valve to the air cleaner are determined so that the volumetric efficiency can be maximized due to pulsations within the intake pipe. However, due to engine installation constraints, it may not be possible to make full use of the pulsation. Furthermore, even if the pulsation can be exploited, the natural frequency of the entire system is fixed, and the pulsation can only be exploited at a certain rotation speed and load. It may also cause a decline.

The present invention solves the above problems, and its purpose is to:
An object of the present invention is to provide an internal combustion engine that can maintain high volumetric efficiency over the entire operating range of the engine.

[Means to solve the problem]

In order to solve the above problems, the present invention provides a resonance box or a resonance pipe in the middle of the main flow part of the intake pipe, separate from the main flow part, and connects this and the main flow part with a plurality of solenoid valves. The two solenoid valves are connected through a passageway, and one of the solenoid valves is opened depending on changes in engine operating conditions such as engine speed, thereby forming a variable resonance system that matches the operating conditions.

[Effect]

By configuring as described above, a variable resonance system is formed that matches the operating conditions of the engine, and resonance (pulsation) is effectively utilized throughout the entire rotational speed range, thereby improving volumetric efficiency throughout the operating range. can.

〔Example〕

One embodiment of the present invention will be described below with reference to FIG. 1. 1 is an intake manifold, 2 is an intake manifold, and 2 is an intake manifold. -Zipunk,
3 is a throttle valve, 4 is a throttle valve, 5 is an air intake/maintenance valve, and 6 is an air cleaner. Reference numeral 20 indicates cylinders of the engine 100, and each cylinder 20 is connected to the intake manifold 1. 21 is the output shaft of the engine.

The above configuration is similar to the conventional one. 23 is engine 10
A rotation detector detects the rotation speed of 0, 22 is a throttle opening detector that detects the opening of the throttle valve 4, and 24 is a controller. Reference numeral 7 denotes a resonance box, and the resonance box 7 is connected to the air intake pipe 5 through a plurality of (three in this case) communication pipes 8, 9, and 10 branched from the air intake mother f5. ing. 11, 12.13 are electromagnetic valves provided in the communication pipes 8, 9.10, and the opening degrees of the electromagnetic valves 11, 12.13 are controlled by a controller 24.

Operating conditions such as the engine speed detected by the rotation detector 23 and the opening of the throttle valve 4 (that is, the load of the engine 100) detected by the throttle opening detector 22 are input to the controller 24. .

Next, the operation of the present invention will be explained with reference to FIGS. 1 and 2.

Near a certain low rotational speed NE, the solenoid valve 11 is open and the other solenoid valves 12, 13 are closed. When the rotational speed approaches N□, the resonance box 7 begins to resonate and the pressure vibration within the resonance box 7 becomes large, and the resonance effect of the entire intake system can further increase the volumetric efficiency. In order to increase the resonance effect, the resonance pipe branch part I in the main intake part, that is, the part from the air cleaner 6 to the intake manifold 1, is designed so that the natural frequency downstream of this part is almost synchronized at the rotation speed Ng. It is located in a suitable position. Next, when the rotational speed increases and approaches Ngll, the solenoid valve 11 closes, and the solenoid valve 12 opens instead, so that the resonance box 7 is connected to the main flow of intake air through the communication pipe 9.

The branch part (2) from the main intake part is provided at a position where the natural frequency downstream of this part is almost in tune with N, and exhibits a large resonance effect to improve the volumetric efficiency. Furthermore, when the speed increases, the solenoid valve 13 opens (the other solenoid valves 11 and 12 are closed), and the volumetric efficiency is greatly improved at the rotation speed N, as described above.

The above effect will be explained with reference to FIG. The solid line in the figure shows the conventional relationship between the volumetric efficiency η7 and the rotational speed N0. Communication pipe 8
When only the solenoid valve 11 is open (that is, the solenoid valve 11 is open), resonance occurs near the rotational speed Ngl, so the volumetric efficiency improves as shown by the broken line. Similarly, when only the communication pipe 9 is open, resonance occurs near the rotational speeds N)i and II, resulting in a volumetric efficiency as shown by the dashed line. When only the communication pipe 10 is open, the volumetric efficiency improves near the rotational speed N as shown by the two-dot chain line. The controller 24 controls the solenoid valve 11,
By opening and closing 12 and 13 as described above according to the rotational speed and varying the branching position of the resonance V (communicating pipes 8 to 10), the volumetric efficiency as shown by the dotted envelope in Figure 2 can be achieved. . This makes it possible to improve volumetric efficiency by making use of resonance throughout the rotational speed range.

〔Effect of the invention〕

The present invention is configured as described above, and according to the present invention, the intake pulsation can be effectively utilized over the entire operating range of the engine, which has the following effects, and the volumetric efficiency is increased. This increases the amount of air charged into the cylinder, making it possible to improve engine output over the entire operating range.

[Brief explanation of the drawing]

FIG. 1 is a system diagram of the intake system of an internal combustion engine according to the present invention, and FIG.
The figure is a diagram showing the effects of the present invention. FIG. 3 is a diagram corresponding to FIG. 1 showing an example of an intake system of a conventional internal combustion engine. 1... Inch-bearing hold, 2... Surge tank, 3... Throttle body, 4... Throttle valve, 5... Air intake nozzle, 6... Air cleaner, 7... Resonance box, 8,9.10...Communication pipe, 1
1,12゜13...Solenoid valve, 20...Cylinder, 2
2... Throttle opening degree detector, 23... Rotation detector, 24... Controller, 100... Engine. 20 Cylinder NEI NEI [NEI[ Rotation speed Figure 2

Claims (1)

[Claims] A resonance box provided separately from the main intake part that communicates with the cylinders of the engine, a plurality of communication pipes branched from the main intake part and connected to the resonance box, and a plurality of communication pipes that are opened and closed. an internal combustion engine, comprising: a solenoid valve; and a controller to which detection signals of engine operating conditions such as engine speed and throttle opening are input, and which controls opening and closing of the solenoid valve based on the input signals. Device.