JPH09100720A - Air intake device for engine - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a sufficient output characteristic in a whole engine speed range of an engine by simplifying a structure and changing both of the length of an air intake passage and a passage area according to engine speed. SOLUTION: An engine air intake device is provided with a first air intake tube 1 communicated with the inside of an engine cylinder, a second air intake tube 2 having a passage intersecting area smaller than that of the first air intake tube 1 and freely moved between a first position P1 fitted in the opening part 1b of an upstream side for the first air intake tube 1 and a second position away from the opening part 1b, a chamber 5 having an intaken air introducing port 6 for housing the second air intake tube 2, to which the opening 1a of the upstream side opening part 1b for the first air intake tube 1, and a driving device 20 for moving the second air intake tube 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an intake system for supplying intake air to a multi-cylinder engine.

[0002]

2. Description of the Related Art It is well known that the length and cross-sectional area of an intake passage (hereinafter referred to as "passage area") are important factors in determining the output characteristics of an engine such as an automobile. JP-A-2-81927, 4-116
No. 226, etc.). Generally, when the length of the intake passage is set to be short and the passage area is set to be large, the filling efficiency at low rotation is poor, but the filling efficiency is good at high rotation, and high output is obtained at high rotation. On the other hand, if the length of the intake passage is set to be long and the passage area is set to be small, the intake resistance will increase at high revolutions and the charging efficiency will deteriorate, but at low revolutions the flow velocity will increase and the inertial supercharging of intake air will increase. As a result, the charging efficiency is improved, and high torque can be obtained at low rotation speed. For this reason, conventionally, various intake devices have been proposed in which the length and area of the intake passage are changed according to the engine speed.

For example, as described in Japanese Utility Model Laid-Open No. 60-26233, an on-off valve is provided in a part of a plurality of intake passages,
There has been an intake device in which an opening / closing valve is opened to increase the passage area as the engine speed increases (prior art 1). Alternatively, as described in Japanese Patent Laid-Open No. 4-116226, two intake ports are formed in one cylinder, and intake passages having different lengths and diameters are communicated with each intake port, and a valve provided in the intake passage is provided. There is an intake device that guides intake air from a long intake passage to one intake opening at low rotation speed by opening and closing, and guides intake air from two intake passages and intake opening at high rotation speed (prior art 2).

[0004]

However, according to the prior art 1, since the length of the intake passage cannot be changed, there is a limit in obtaining high filling efficiency in both low and high rotational speed regions. . Further, in the prior art 2, although the substantial passage length and passage area can be changed between low rotation speed and high rotation speed, two intake passages for low rotation and high rotation are separately provided. I had to set it up. Further, since there are two intake systems for each cylinder, there is a drawback that the intake system becomes complicated and also heavy in weight.

The present invention solves the above problems and has a simple structure in which both the length and the passage area of the intake passage are changed in accordance with the engine speed, so that the entire engine speed range is sufficient. It is an object of the present invention to provide an intake system for an engine that can obtain various output characteristics.

[0006]

In order to achieve the above object,
The gist of the present invention according to claim 1 is the first intake pipe communicating with the cylinder of the engine, and the cross-sectional area of the passage is smaller than that of the first intake pipe, and the opening on the upstream side of the first intake pipe. A second intake pipe movable between a first position fitted into the second intake pipe and a second position separated from the opening; An intake system for an engine, comprising: a chamber facing an opening of an upstream side opening of the first intake pipe; and a drive device for moving the second intake pipe. Here, “the cross-sectional area of the passage is smaller than that of the first intake pipe” does not require that the cross-sectional area of the passage is smaller than that of the first intake pipe over the entire region, and it is sufficient if a part of the cross-sectional area is satisfied. According to a second aspect of the present invention, there is provided the engine air intake device, wherein the second air intake pipe of the first aspect is formed of a synthetic resin containing reinforcing fibers. The intake system for an engine according to a third aspect of the present invention,
The upstream opening of the first intake pipe and the upstream opening of the second intake pipe according to claim 1 or 2 are formed in a bell mouth shape whose inner diameter increases as it goes upstream.

According to the first aspect of the present invention, the second intake pipe is fitted into the upstream side opening of the first intake pipe when the engine speed is low. As a result, the intake air flows into the cylinder through the second intake pipe and the first intake pipe after entering from the inlet of the chamber. At this time, the intake passage has a length close to the sum of the lengths of the first intake pipe and the second intake pipe, and the passage area of the second intake pipe is smaller than that of the first intake pipe, so that the intake passage is substantially Since the passage area is also small, the flow velocity is high and the inertia of the intake air is large, and the charging efficiency is improved by the inertia supply. On the other hand, at the time of high rotation, the first intake pipe is moved to a position separated from the opening of the second intake pipe. Thus, after the intake air is introduced from the introduction port of the chamber, it directly enters the first intake pipe without flowing in the second intake pipe and is guided into the cylinder, so that the length of the intake passage is substantially shortened. . Moreover, since the passage area of the first intake pipe is larger than that of the second intake pipe, the intake resistance is reduced and the filling efficiency is improved.

According to the second aspect of the present invention, since the second intake pipe is made of synthetic resin, not only it contributes to weight reduction, but also the operation of moving the second intake pipe is facilitated. According to the third aspect of the present invention, since the opening on the upstream side of the first intake pipe and the opening on the upstream side of the second intake pipe have a bellmouth shape, the suction resistance is reduced.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail. 1 to 3 show one embodiment of an engine intake device according to the present invention (hereinafter referred to as "intake device").
2 is an exploded perspective view of the intake device, FIG. 2 and FIG. 3 are schematic configuration diagrams of the intake device, FIG. 2 shows a state at low rotation, and FIG. 3 shows a state at high rotation of the intake device. Is.

The main component of this intake system is a first intake pipe 1, a second intake pipe 2, an intake box 3, a flange lid 8 and a drive unit 20. The air intake box 3 is a box body whose one side surface is open. A part of the opening edge of the air intake box 3 becomes a projecting edge, and a screw hole is provided around the opening. If the flange lid 8 that can cover this opening is covered and the intake box 3 and the flange lid 8 are fixed by bolts using the screw holes, the chamber 5 serving as a surge tank is formed. The chamber 5 accommodates the second intake pipe 2 and is provided with an inlet 6 for the intake air A that communicates with an air cleaner (not shown). An intake manifold 4 is formed by a plurality of (four in this case) first intake pipes 1 and second intake pipes 2 using the chamber 5 as a collecting pipe.

The first intake pipe 1 is a pipe-shaped branch pipe that communicates with each intake port of the cylinder head. The engine-side mounting flange 7 and the above-mentioned flange lid 8 are integrated at both ends of the first intake pipe 1, respectively, to form a flanged intake port α.
To form If the mounting flange 7 of the intake port α is fixed to the engine side, the first intake pipe 1 communicates with a cylinder (not shown) of the engine E. Further, when the flange lid 8 is fixed to the intake box 3 with the bolt 9, the opening 1a of the first intake pipe 1, which is the upstream side of the intake air A, faces the chamber 5 (FIG. 2). The tip of the opening 1b on the upstream side of the first intake pipe 1 is formed in a bell mouth shape whose inner diameter increases as it goes upstream of the intake air A. This is to reduce the inhalation resistance. The shape of the intake port α and the intake box 3 described above is relatively simple, and can be a die cast product or an injection molded product. Intake port α, intake box 3
The material may be metal, heat resistant resin, or the like.

The second intake pipe 2 is a pipe-shaped branch pipe arranged so that each opening 2b on the base end side faces each opening 1b of the first intake pipe 1. The passage area of the second intake pipe 2 is set smaller than that of the first intake pipe 1, and the outer diameter of the second intake pipe 2 is substantially the same as the inner diameter of the first intake pipe 1 as shown in FIG. Alternatively, it is set to be slightly smaller than the inner diameter of the first intake pipe 1. The passage areas of the first intake pipe 1 and the second intake pipe 2 are represented by average values. The tip of the opening 2a on the upstream side of the second intake pipe 2 also has a bell-mouth shape to reduce intake resistance. The second intake pipe 2
The opening 2b on the downstream side is formed so that only the inner diameter increases as it goes downstream of the intake air A.

The four second intake pipes 2 arranged in parallel are integrally connected by three connecting plate portions 2c to form a composite pipe body β.
It has become. Such a composite pipe body β is an injection molded product,
Blow-molded products will reduce the weight. In particular, a complicated shape having a plurality of hollow pipes is suitable for blow molding, and if it is a blow molded product, cost merit can be accepted and it is more preferable. As a material for the composite tube body β, for example, a thermoplastic resin containing a reinforcing fiber having excellent heat resistance such as glass fiber reinforced nylon or polypropylene is suitable.

By the way, in the present embodiment, the conduits of the second intake pipe 2 of FIG. 1 are independent, but as shown in FIG. 4, the second intake pipe 2 is branched on the downstream side. It can also be shaped. Further, as shown in FIG. 5, the second intake pipe 2 may be one and the first intake pipe 1 may be a manifold pipe. However, in such a case, the passage area of the second intake pipe 2 is set smaller than the passage area of the upstream portion of the first intake pipe 1.

A bracket 11 integral with the shaft 10 is screwed to the connecting plate portion 2c with a bolt or the like. The second intake pipe 2 is fixed to the shaft 10 via the connecting plate portion 2c and the bracket 11. The shaft 10 includes an intake box 3
2 is rotatably supported in the support hole 3a, and the axis O of the shaft 10 in FIG. 2 is located at the center of curvature of the curved pipe forming the second intake pipe 2. In this way, the second intake pipe 2 is rotatably supported by the intake box 3 along the direction in which the curved pipe is bent. Then, the opening 2b on the downstream side has the first intake pipe 1
Position P1 (FIG. 2) fitted in the opening 1b on the upstream side of the second position P2 and second position P2 separated from the opening 1b.
It is attached to the air intake box 3 so as to be movable between (FIG. 3). Specifically, the second intake pipe 2 can be reciprocated between the first position P1 and the second position P2 by the drive device 20 and the control device 30 according to the engine speed.

The drive unit 20 is composed of, for example, a prime mover 21 such as an actuator and a motor, a rod 22 which is expanded and contracted by the prime mover 21, and a link 23 attached to the tip of the rod 22 (FIG. 2). . Link 2
3 is fixed to the shaft 10 and slightly swings as the rod 22 expands and contracts to rotate the shaft 10 so that the second intake pipe 2 is inserted through the bracket 11.
Is reciprocated between the first position P1 and the second position P2. Although the second intake pipe 2 is rotated around the shaft 10, the second intake pipe 2 may be linearly slid and moved.

The control device 30 comprises a rotation speed detector 31 and a microcomputer (microcomputer) 32. The rotation speed detector 31 detects the rotation speed of the engine and outputs a rotation speed signal to the microcomputer 32. For example, a crank angle detector can be adopted. The microcomputer 32 stores a predetermined rotation speed that is a boundary value between low speed rotation and high speed rotation, compares the rotation speed input from the rotation speed detector 31 with the boundary value, and drives the prime mover 21. Through the above, the second intake pipe 2 is moved to the first position P1 during low rotation, while the second intake pipe 2 is moved to the second position P2 during high rotation. Here, the rotational speed is determined by the microcomputer 32 and the second intake pipe 2 is drive-controlled by the dedicated prime mover 21, but the configuration is not necessarily limited to this. For example, the structure may be such that the governor (governor) of the engine is used as a drive source and the second intake pipe 2 is driven by the operation of the governor.

Next, the operation of the intake system will be described. When the engine speed is low and the engine speed is low, the rod 22 is extended and the opening 2b of the second intake pipe 2 is fitted in the opening 1b of the first intake pipe 1 as shown in FIG. Therefore, the intake air A flows into the chamber 5 from the introduction port 6 and then flows into the cylinder of the engine E through the second intake pipe 2 and the first intake pipe 1, and therefore, at the time of low rotation, the intake manifold The intake passage at 4 is a length close to the sum of the lengths of the first intake pipe 1 and the second intake pipe 2. Moreover, since the intake air A passes through the second intake pipe 2 having a smaller passage area than the first intake pipe 1, the substantial passage area of the intake passage is also reduced. Therefore, when the engine speed is low, the flow rate of the intake air A is increased and the inertia of the intake air is increased, so that the charging efficiency is improved by the inertia supercharging. As a result, high torque can be obtained at low speed.

On the other hand, when the engine speed becomes higher than the boundary value, the microcomputer 32 contracts the rod 22 via the prime mover 21. This makes link 2
3, the shaft 10 and the bracket 11 rotate along the direction in which the second intake pipe 2 is bent, and the second intake pipe 2 moves from the first position P1 to the second position P2 in FIG. . Therefore, the intake air A flows into the chamber 5 through the introduction port 6 of the chamber 5 and then flows into the cylinder of the engine E through the first intake pipe 1 without flowing in the second intake pipe 2. . As described above, at high rotation speed, the substantial length of the intake passage in the intake manifold 4 becomes the length of the first intake pipe 1 and becomes short. Moreover, the intake air A does not pass through the second intake pipe 2 having a small passage area, and the passage area is also large. Thus, at the time of high rotation, the intake resistance is reduced and the charging efficiency is improved. As a result, even at high revolutions,
High output is obtained. Although the second intake pipe 2 is set to the first position P1 at the time of low rotation and the second position P2 at the time of high rotation, the torque of the engine is detected to detect the low torque and high rotation (for example, idling). May perform various controls such as setting the second intake pipe 2 to the first position P1.

Unlike the conventional method in which one cylinder is provided with two intake passages for low rotation and high rotation, the intake device configured as described above moves the second intake pipe 2,
Since the intake passages for low rotation and high rotation are formed, the structure of the intake manifold 4 is simplified and the weight is reduced. When the engine is running at low speed, the intake passage is long and the passage area is small, so that the flow velocity is high and the intake air is supercharged, so that the charging efficiency is improved and a large torque is obtained. On the other hand, at the time of high rotation, the intake passage is short and the passage area is large, and the intake resistance is small, so that a high output is obtained. Further, since the second intake pipe 2 is made of synthetic resin containing reinforcing fibers, the second intake pipe 2
Not only is it lighter in weight, but it is also possible to quickly switch between low speed and high speed. There is no risk of obstructing the flow of intake air at the time of switching. Further, since the opening 1b of the first intake pipe 1 is formed in a bell mouth shape, the suction resistance from the chamber to the first intake pipe 1 is small, and the output at the time of high rotation is improved. Since the opening 2a of the second intake pipe 1 is also formed in a bell mouth shape, the flow of intake air from the chamber 5 to the second intake pipe 2 smoothly flows, and the torque can be increased at low rotation speed.

In the present invention, the present invention is not limited to those shown in the above embodiments, but can be variously changed within the scope of the present invention depending on the purpose and application. The shapes and materials of the first intake pipe 1, the second intake pipe 2, the intake box 3, the flange lid 8, the drive device 20, etc. can be selected as appropriate. For example, the opening 1b of the first intake pipe 1 is
It is not necessary to bulge to the chamber 5 side, and the root portion of the first intake pipe 1 that joins with the flange lid 8 may be enlarged in diameter to form an opening into which the second intake pipe 2 is easily fitted. Although the number of the first intake pipe 1 and the number of the second intake pipe 2 are four in the above-mentioned embodiment, various numbers can be adopted according to the intake port of the cylinder head.

[0022]

As described above, the engine intake system of the present invention has a simple structure, but at the same time, not only the intake passage but also the passage area can be changed by fitting or disconnecting the first intake pipe and the second intake pipe. As a result, the filling efficiency can be increased and a large torque can be obtained, and an excellent effect of improving the performance can be exhibited.

[Brief description of the drawings]

FIG. 1 is an exploded perspective view of an intake device for an engine showing an embodiment of the present invention.

FIG. 2 is a schematic configuration diagram of an intake device showing a state of the engine at a low rotation speed.

FIG. 3 is a schematic configuration diagram of an intake device showing a state of the engine at a high rotation speed.

FIG. 4 is a schematic view of first and second intake pipes according to another embodiment.

FIG. 5 is a schematic view of first and second intake pipes according to still another embodiment.

[Explanation of symbols]

 1 first intake pipe 1a opening 1b opening 2 second intake pipe 2a opening 5 chamber 6 inlet 20 drive device A intake P1 first position P2 second position

Claims (3)

[Claims] 1. A first intake pipe (1) communicating with the inside of a cylinder of an engine, and a cross-sectional area of the passage is smaller than that of the first intake pipe, and the first intake pipe (1) is fitted into an upstream opening of the first intake pipe. A second intake pipe (2) movable between a first position and a second position separated from the opening, and an intake port for intake air,
A chamber (5) for accommodating the second intake pipe and facing an opening of an upstream side opening of the first intake pipe; and a drive device (20) for moving the second intake pipe. Characteristic engine intake device. 2. The intake system for an engine according to claim 1, wherein the second intake pipe is made of a synthetic resin containing a reinforcing fiber. 3. The method according to claim 1 or 2, wherein the opening on the upstream side of the first intake pipe and the opening on the upstream side of the second intake pipe are formed in a bell mouth shape whose inner diameter increases as it goes upstream. Engine intake system.