JPH0612199Y2 - Intake manifold structure for engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION <Industrial field of application> The present invention is an intake air for an engine having two intake passages, which can selectively switch the communication depending on the rotation speed range of the engine. Regarding the manifold structure.

<Prior Art> In the case of a vehicle engine, it is preferable that the torque characteristic is flat because the operating speed range is relatively wide.

By the way, in the case of a naturally aspirated engine, the flow passage resistance of the intake passage is made as small as possible in the high speed rotation range to increase the filling efficiency of the air-fuel mixture as much as possible, and the intake passage is made thin in the low speed rotation range. It is desirable to make it longer and to increase the intake flow velocity as much as possible, and at the same time, to make effective use of the inertial effect.

From this point of view, an intake manifold having two intake passages per cylinder provided in parallel in the intake port of the engine, and communication between these passages with respect to the combustion chamber can be selectively switched by a sub-throttle valve. The device is, for example, JP-A-5
It is proposed in Japanese Patent Publication No. 8-135354.

<Problems to be solved by the invention> On the other hand, in order to reduce the flow resistance of intake air, it is most advantageous to have a circular cross section when the intake passages have the same cross-sectional area. When these pipes are provided in parallel, the space efficiency is lowered and the intake manifold structure is inevitably increased in size.

In view of such inconvenience of the conventional technology, the main object of the present invention is to provide an intake manifold structure including a plurality of intake paths,
It is an object of the present invention to provide an improved intake manifold structure for an engine that can be realized with a relatively small external size.

<Means for Solving the Problems> According to the present invention, such an object is to provide a first passage having a valve opened in a high speed rotation range and a second passage communicating in the entire rotation range.
An intake manifold structure for an engine having an intake passage formed of a passage for each cylinder and a surge tank provided at the upstream end of the intake passage in common for each cylinder, wherein the intake passage is connected to an engine body. A horizontal extending portion that extends in a substantially horizontal direction from the above portion, and an upward bending portion that bends upward on the intake upstream side of the horizontal extending portion, and the upward bending portion and the surge tank via a spacer. The first passage and the second passage are separated from each other by a common partition that is continuously formed in the upstream portion of the spacer and the curved portion, and are arranged in parallel, and the first passage has a cross-sectional shape. The second passage is formed in a circular shape on the inner peripheral side of the curved portion, and the second passage is defined on the outer peripheral side of the curved portion with a square cross-sectional shape. On the spacer It is achieved by providing an intake manifold structure for an engine, characterized in that provided on the side corresponding to kicking the first passage.

<Operation> As described above, if the intake passage is extended in the horizontal direction from the engine body and then curved upward, and the surge tank is connected to the upstream end of the upward curved portion, two intake passages are provided. In addition, it is possible to suppress an increase in the horizontal dimension when viewed from the crankshaft direction of the engine. In particular, if a passage that communicates in the entire rotation range is provided as a rectangular cross section on the outer peripheral side of the curved portion, the length of the pipeline can be maximized in a limited space, so low-speed performance can be improved and pipeline resistance can be improved. If the cross-sectional shape of the passage communicating with each other in the high-speed rotation range, which is greatly affected by, is circular, the performance deterioration in the high-speed rotation range can be avoided. Further, by combining the perfect circle contour and the square contour, the outer dimensions can be reduced as compared with the case where the perfect circles are arranged side by side. In addition to this, if a valve is provided on the spacer provided at the connection between the upward curved portion and the surge tank, manufacturability can be improved as compared with the case where the valve is provided on the intake manifold itself.

<Embodiment> A preferred embodiment of the present invention will be described in detail below with reference to the accompanying drawings.

FIG. 1 shows a main part of an engine to which an intake manifold structure constructed according to the present invention is applied. An intake manifold 2 is bolted to a side surface of the engine body 1 to introduce outside air into a combustion chamber provided inside the engine body 1.

The intake manifold 2 extends in a substantially horizontal direction from a connection portion of the engine body 1 with an intake port, and is then curved upward with an appropriate curvature. By being isolated, the inner peripheral side passage 4 as the first passage and the outer peripheral side passage 5 as the second passage.
The two passages are arranged side by side. The upstream ends of both of the passages 4 and 5 are opened in a substantially horizontal plane, and a butterfly valve 6 capable of connecting / disconnecting the communication of only the inner peripheral passage 4 is opened at this opening end.
A surge tank 8 common to all cylinders is connected via a spacer 7 provided with.

The surge tank 8 is in the form of an elongated box extending in the cylinder row direction of the engine, has a volume sufficient to absorb intake pulsation, and has a throttle body (not shown) in which a throttle valve is provided at one end thereof. ) Are connected, and the intake air flow rate can be controlled by operating the accelerator pedal in the same manner as a known engine. The surge tank 8 and the inside of the head cover of the engine body 1 are connected by a tube 9 so that blow-by gas can circulate.

A fuel injection valve 1 for injecting fuel corresponding to each cylinder is provided in the vicinity of a connection portion of the intake manifold 2 with the engine body 1.
0 is provided. The fuel injection valve 10 directly injects fuel toward an intake port (not shown) of the engine.

The horizontal extension portion 21 and the upward bending portion 2 of the intake manifold 2
A stay 11 is attached between the lower surface of the engine body 1 and the lower surface near the connecting portion to support the weight of the intake manifold 2.

As shown well in FIG. 2, the intake manifold 2 is formed with independent pipe lines 2a to 2d for each cylinder, and the upstream ends thereof have the openings 4a and 5a of the two passages 4 and 5 as described above.
Are opened in parallel. Of these openings 4a and 5a, the inner peripheral side opening 4a has a perfect circular cross section and the outer peripheral side opening 5a has a rectangular cross section. In the low speed rotation range of the engine, the butterfly valve 6 is closed to suck intake air only from the outer peripheral side opening 5a, and in the high speed rotation range, the butterfly valve 6 is opened to open both openings 4a. Intake air from 5a.
By doing so, the intake flow velocity is increased in the relatively small diameter portion in the low speed rotation region, and at the same time, the inertial effect of intake air is effectively utilized by passing through the outer peripheral side passage 5 having a longer passage extension. In the high speed rotation range, the intake resistance can be reduced by passing through both passages 4 and 5. Further, as is clear from FIG. 1, the intake manifold 2 is unified from the middle of the curved portion, and its longitudinal sectional shape is a funnel shape in which the sectional area gradually decreases toward the downstream side.
This also further increases the intake charging efficiency in the high speed rotation range.

By the way, the cross-sectional shape of the intake passage is preferably a circular cross-section in order to keep the flow path resistance low, but when a plurality of passages are arranged side by side as described above, in terms of the shape of the above-mentioned embodiment, the curved portion has a curved shape. At the same time as the radius becomes large, the amount of mess in the partition wall 3 becomes large, which contributes to an increase in weight.

Therefore, in the present invention, as shown in the above embodiment, by making the passage in the low speed rotation region side, which is relatively less affected by the flow passage resistance, that is, the outer peripheral side passage 5, the cross-sectional shape is square, the above-mentioned problem is solved. Trying to avoid.

<Effect of device> As described above, according to the present invention, it is possible to avoid the performance deterioration in the high speed rotation region by making the passage on the side corresponding to the high speed rotation region, which is particularly influenced by the pipeline resistance, have a circular cross section. Since the passage corresponding to the low-speed rotation range where the influence of the static pipe resistance is small has a rectangular cross section, compared with the case where pipes with a perfect circular cross section are installed side by side, the intake manifold structure is seen especially from the crankshaft end of the engine. Further, it is possible to reduce the outer dimension in the horizontal direction, and at the same time, it is effective in reducing the wall thickness of the partition wall between both passages and reducing the weight.

In particular, as shown in the above embodiment, if the passage corresponding to the high speed rotation region is circular and the opening / closing valve is provided on the same passage side in the spacer, the valve mechanism can be assembled in advance in the spacer, so the intake manifold itself Compared with the structure in which the on-off valve is provided in the, the closing accuracy of the on-off valve can be easily ensured, and the intake manifold structure by the variable intake pipe length method can be realized without lowering the manufacturability. It is extremely effective in achieving high engine performance at low cost.

[Brief description of drawings]

FIG. 1 is a vertical cross-sectional view of an intake manifold showing a state of assembly to an engine. FIG. 2 is a top view of the intake manifold shown in FIG. DESCRIPTION OF SYMBOLS 1 ... Engine main body, 2 ... Intake manifold 2a-2d ... Pipe line, 3 ... Partition wall 4 ... Inner peripheral side passage, 4a ... Opening 5 ... Outer peripheral side passage, 5a ... Opening 6 ... Butterfly valve, 7 ... Spacer 8 ... Surge Tank, 9 ... Tube 10 ... Fuel injection valve, 11 ... Stay

Claims (1)

[Scope of utility model registration request] 1. An intake passage which is provided for each cylinder and comprises a first passage having a valve opened in a high-speed rotation region and a second passage which communicates in the entire rotation region, and an intake passage upstream of the intake passage, which is common to all the cylinders. An intake manifold structure for an engine having a surge tank provided, wherein the intake passage has a horizontal extension extending substantially horizontally from a connection portion with the engine body, and an intake upstream side of the horizontal extension. And the surge tank is connected to the surge tank via a spacer, and the first passage and the second passage are continuous to the upstream portion of the spacer and the bending portion. Are separated from each other by a commonly formed common partition wall, the first passage has a circular cross-sectional shape and is defined on the inner peripheral side of the curved portion, and the second passage has the cross-sectional shape. Square A valve that is formed on the outer peripheral side of the curved portion and that is opened in the predetermined rotation range is provided on the side of the spacer that corresponds to the first passage. Manifold structure.