JPH03281923A - Air intake device of engine - Google Patents

Abstract

PURPOSE:To improve fuel consumption by providing communicating passages which connect the throttle downstream of respective cylinders, installing a means to open the communicating passages at the time of partial loading, and ensuring throttle control with good responsiveness to increase inside EGR at the time of partial loading. CONSTITUTION:In respective independent air intake passages 17R, 17L which are constituted from branch pipes 15R, 15L of a manifold upper 7 and air intake pipes 8R, 8L of a manifold lower 6, throttle valves 18 of butterfly type are installed near the position where the manifold lower 6 is connected to cylinder heads 1R, 1L. With this constitution, two holes 24, 25 with large diameter extending in the row direction of cylinders are provided in a connecting part 9 to connect air intake pipes 8R, 8L of the manifold lower 6. Passages 27R, 27L which lead to air intake ports 3R, 3L of the respective cylinders in right and left banks open to the hole 24 on the right side. Besides, a plunger valve which opens and closes the passages 27R, 27L is inserted into the large diameter hole 24 on the right side, and is made to open at the time of partial loading.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to an intake system for an engine in which a throttle valve is provided in each independent intake passage of each cylinder branching from an intake collecting section.

(Prior Art) A butterfly-type flow control valve is usually used as a throttle valve for controlling the intake air amount of an engine. and,
A throttle valve is provided on one side upstream of the surge tank where the independent intake passages of each cylinder converge, and the intake air amount determined by the opening degree of this one throttle valve is uniformly distributed to each cylinder. (For example, see Japanese Utility Model Application No. 615330). However, high-output engines and the like have been known to employ so-called multiple throttles in order to improve responsiveness. A multiple throttle is a system in which a throttle valve is provided in the independent intake passage of each cylinder downstream of the surge tank, and these throttle valves are linked to adjust the intake air amount for each cylinder. The volume is significantly reduced, improving the responsiveness of intake air volume control.

(Problems to be Solved by the Invention) By the way, in order to improve the fuel efficiency of the engine, the overlap of the intake and exhaust valves is increased to increase the so-called internal EGR (Exhaust Gas Recirc) during partial load.
It is known that it is effective to increase the However, in the case of an engine that employs multiple slot lengths as described above, the throttle downstream volume of each cylinder is small, so the pressure at the intake port during overlap is high (negative pressure or weak), which causes the overlap to become large. However, a problem has arisen in that internal EGR is prevented from increasing and does not lead to improved fuel efficiency.

The present invention has been made in view of these problems, and aims to improve fuel efficiency by increasing internal EGR during partial load while ensuring responsive throttle control by employing multiple throttles. With the goal.

(Means for Solving the Problems) An engine intake system according to the present invention is capable of freely switching the independent intake passages of each cylinder of an engine with multiple throttles into communication and non-communication downstream of the throttle. This system achieves both improved responsiveness and improved fuel efficiency by switching the state, and its configuration consists of an engine intake system in which a throttle valve is provided in each cylinder's independent intake passage branching from an intake collecting section. The present invention is characterized in that a communication passage connecting downstream throttles of each cylinder is provided, and means is provided to open the communication passage during partial load to allow the downstream throttles of each cylinder to communicate with each other.

(Function) The intake air amount of the engine is adjusted by the throttle valve provided in the independent intake passage of each cylinder, and especially when the communication passage is closed and the independent intake passage of each cylinder is disconnected,
By reducing the volume downstream of the throttle of each cylinder, the responsiveness of throttle control is improved. In addition, at partial load, the communication passage is opened and the throttle downstream of each cylinder communicates with each other, so that the throttle downstream pressure of each cylinder is averaged, so that the intake port is in a strong negative pressure state during intake and exhaust overlap. This increases internal EGR and improves fuel efficiency.

(Example) Examples will be described below based on the drawings.

FIG. 1 is a partially cutaway front view showing an intake system for a V-type six-cylinder engine together with a cylinder head according to an embodiment of the present invention, and FIG. 2 is a plan view of the intake manifold lower.

In FIG. 1, IR is a cylinder head of one right bank of a V-type 6-cylinder engine, and IL is a cylinder head of the other bank. Cylinder head IR, IL of each bank
is provided with combustion chamber recesses 2R, 2L for the cylinders of each bank on the lower surface, and intake ports 3R, 3L of each cylinder extend from the opposing inner surface of each cylinder head lR1+- to the four combustion chamber parts 2R12L. Open and exhaust port 4R, 4
,, are intake ports 1311,3. , and is formed to open on the outer surface facing the .

The intake manifold 5 is divided into a manifold lower 6 and a manifold upper 7 and has a suspended structure. Manifold lower 〇 corresponds to the intake ports 3R and 3L of each cylinder of the left and right banks, which are arranged offset, and is inverted V at a position offset in the longitudinal direction of the engine.
It has intake pipes 8R, 81, which form a letter shape and extend from side to side,
These are integrally connected via a connecting part 9 extending in the longitudinal direction of the engine between the connecting positions with the left and right cylinder heads lR, IL, and the upstream end side is connected to the intake pipes 8R, 8L of the opposite cylinders of the left and right banks. are integrally connected by a flange portion 10 to form three pairs of intake pipes 11, 12, and 13.

Moreover, the manifold upper 7 includes surge tanks 14R and 14L, each located above the left and right hangs, and the surge tanks 14R.

The branch pipes 15R and +5L are branched from 14L and connected to the intake pipes 8R and 8L of the manifold lower 6. are integrally connected. The manifold lower 6 and the manifold upper 7 are connected to each other at these flange portions 10.16.
or connected and bolted up.

Branch pipe 15 of the manifold upper 7. l.

15L and the intake pipes 8R and 8L of the manifold lower 6 constitute an independent intake passage 17R1+7L for each cylinder.

A butterfly-type throttle valve 18 is provided in each of the independent intake passages 17R, 17L near the connection position of the manifold lower 6 to the cylinder head IRIL, and furthermore, a butterfly-type throttle valve 18 is provided in the vicinity of the connection position of the manifold lower 6 to the cylinder head IRIL.
A fuel injection valve 19 is arranged adjacent to the side.

Each throttle valve 18 is independently connected to its respective pivot shaft 2OR.
,20,. And intake pipe pair 11,1
2. Every 13, the left and right bank throttle valves 18 are connected to link 2.
1, they are interlockably connected. Further, the pivot shafts 2OR, 2OL of each intake pipe pair 11, 12, 13 are operably connected via an adjustment mechanism (not shown) for each bank, and the left throttle valve of the center intake pipe pair 12 is The 18 pivot shafts 2OR, 20L are connected via a throttle link 23 to a throttle lever 22 rotatably supported on the right side surge tank 14R, whereby the throttle lever 22 is connected via an accelerator wire (not shown). All the throttle valves 18 are configured to be opened and closed in conjunction with each other when rotated.

Inside the connecting portion 9 that connects the intake pipes 8R98L of the manifold lower 6, two large diameter holes 24 and 25 extending in the direction of the cylinder row are provided, and two small diameter holes 26Il and 26L are provided on the left and right sides thereof. is provided. Of these, the hole 24 with the larger diameter is located on the right side in Figure 1.
, passages 27R and 27L that connect to the intake ports 3R and 3 of each cylinder of the left and right banks are open. In addition, another hole 25 with a large diameter is I, S, C, (Id
The small diameter holes 26R and 26L on the left and right constitute a passage for P, C, and V
, (Po5itive Crankcase Ve
ntilation).

In the large diameter hole 24 on the right side, there is a plunger valve 2 that opens and closes the passages 27R and 27L that open to the hole 24.
8 is inserted. This plunger valve 28 is connected to a negative pressure actuator 29 as schematically shown in FIG. A negative pressure tank 31 that introduces intake negative pressure is connected to the working chamber 29a of the negative pressure actuator 29 via a check valve 30. Furthermore, a three-way solenoid valve 32 is provided between the negative pressure actuator 29 and the negative pressure tank 3I. The working chamber of the negative pressure actuator 29 is communicated with the negative pressure tank 31 side by this three-way solenoid valve 32, or is opened to the atmosphere.

The control unit 33 controls the energization of the three-way solenoid valve 32 in an ON/OFF manner based on a map shown in FIG. 4 based on the engine speed and intake air amount.

Then, at extremely light loads including idling or near full load, the power to the three-way solenoid valve 32 is turned off.
As a result, the working chamber 29a of the negative pressure actuator 29 is opened to the atmosphere, and the plunger valve 28 closes the passages 27R and 27L to each cylinder, thereby opening the intake port 3R of each cylinder.

3L becomes disconnected. As a result, dilution gas is suppressed to a small level under extremely light loads such as during idling, thereby stabilizing combustion, and near full load there is no interference between cylinders, ensuring responsiveness of throttle control. Furthermore, during partial load, the three-way solenoid valve 32 is energized, negative pressure is supplied to the working chamber 292L of the negative pressure actuator 29, and the plunger valve 28 is pulled. Then, each passage 27R127L is opened, and the intake ports 3R and 3L of each cylinder communicate with each other via the hole 24. Here, the overlap of intake and exhaust is set to be large by advancing the opening timing of the intake valve, and therefore, at partial load, the intake ports 3R and 3L of each cylinder communicate with each other as described above, and the throttle downstream pressure is averaged. When this happens, the negative pressure becomes stronger and internal EGR increases. As a result, pumping loss is reduced, fuel efficiency is improved, and NOx emissions are reduced.

(Effects of the Invention) Since the present invention is configured as described above, while ensuring good response characteristics by multiple throttles, internal EGR
can be increased to improve fuel efficiency under partial load.

[Brief explanation of the drawing]

Fig. 1 is a partially cutaway front view of an embodiment of the present invention, Fig. 2 is a plan view of the intake manifold lower in the embodiment, Fig. 3 is a schematic diagram of the control system of the embodiment, and Fig. 4 is the same. FIG. 3 is a diagram of the operating range of the three-way solenoid valve in the embodiment. 3R, 3L: Intake port, 5: Intake manifold, 6:
Manifold lower 7 Manifold upper 14
R, 141-: surge tank, 17R, 170, independent intake passage, 18: throttle valve, 24 holes, 27. ．． 27
L: passage, 28 nib lunge valve, 29: negative pressure actuator, 32. King solenoid valve.

Claims (1)

[Claims] (1) In an engine intake system in which a throttle valve is provided in each independent intake passage of each cylinder branching from an intake collecting section, a communication passage is provided to connect downstream of the throttle of each cylinder, and the communication passage is closed during partial load. An intake system for an engine, characterized in that it is provided with means that opens to allow the downstream of the throttle of each cylinder to communicate with each other.