JP2595798B2 - Intake control device for internal combustion engine - Google Patents

Description

The present invention relates to an intake control device for an internal combustion engine.

[Conventional technology]

2. Description of the Related Art An internal combustion engine that controls the amount of engine intake air by controlling the opening of a throttle valve disposed in an intake passage in accordance with the engine operating state to adjust the throttle of intake air is widely used. However, in this case, since the intake air is throttled by the throttle valve during the engine partial load operation, the engine combustion chamber becomes negative pressure during the engine intake stroke, and as a result, a force is required to lower the piston, and thus the pumping loss is reduced. There is a problem that occurs. In order to solve this problem, instead of controlling the intake air amount by changing the opening of the throttle valve as described above, the intake air amount is controlled before the intake bottom dead center according to the engine operating state without reducing the intake air. 2. Description of the Related Art A Miller cycle internal combustion engine that controls the amount of intake air by closing an intake passage to change the period during which intake air flows into an engine combustion chamber (see Japanese Patent Application Laid-Open No. 62-174531). In the Miller cycle internal combustion engine disclosed in Japanese Patent Application Laid-Open No. 62-174531, a cylindrical through-hole is formed substantially perpendicular to the axis of the intake passage and penetrates the intake passage, and the intake passage communicates with the through-hole. A sleeve having a possible opening is inserted, and a valve body that rotates around the axis of the through hole in synchronization with the engine is inserted into the sleeve, and the opening and closing of the sleeve is controlled by the valve body. Here, the sleeve is rotationally displaced around the axis of the through hole according to the engine operating state,
As a result, the opening / closing timing of the intake passage by the valve body is changed with respect to the opening / closing valve timing of the intake valve, and thus the period of inflow of intake air into the engine combustion chamber is changed, and the engine intake air amount is controlled. It has become.

[Problems to be solved by the invention]

Incidentally, in order to accurately obtain a predetermined intake air amount according to the engine operating state in such a Miller cycle internal combustion engine, it is necessary that the intake passage be properly closed when the valve element is closed. For this purpose, it is desirable to minimize the clearance between the outer peripheral edge of the valve body and the inner wall surface of the sleeve. However, in the above-described Miller cycle internal combustion engine, the outer peripheral edge of the valve body must be formed to have an outer diameter smaller than the inner diameter of the sleeve by an amount corresponding to the amount of deviation due to a processing error between the axis of the through hole and the rotation axis of the valve body. As a result, there is a problem that the clearance between the outer peripheral edge of the valve body and the inner wall surface of the sleeve becomes large. In particular, in a multi-cylinder, a plurality of intake passages arranged in parallel with each other are provided, and a cylindrical through-hole extending in a direction substantially perpendicular to the intake passages across the intake passages is formed. When the valve body is rotated in such a manner, the cylindrical through hole becomes long, so that it is difficult to secure good straightness and cylindricity of the through hole. There is a problem that it is more difficult to reduce the clearance between the wall surfaces than in the case of a single cylinder internal combustion engine.

[Means for solving the problem]

In order to solve the above-mentioned problems, according to the present invention, a valve body is provided which forms a cylindrical through-hole passing through the intake passage at a substantially right angle with the intake passage axis, and rotates around the through-hole axis in synchronization with the engine. In the intake control device in which the valve is inserted into the through hole to control the opening and closing of the intake passage by the valve element, the entire outer surface of the valve element is covered with the machinable resin, Almost the entire outer peripheral edge of the valve body farthest from the valve body is formed at the time of assembling the valve body and has an outer diameter larger than the inner diameter of the through hole when the temperature of the intake passage wall surface and the temperature of the valve body are substantially equal. Almost the whole of the machinable resin covering the outer peripheral edge of the body contacts the inner wall surface of the through hole.

[Action]

When assembling the valve element, the valve element is contracted by a method such as cooling, and the contracted valve element is inserted into the through hole.
Next, when the temperature of the intake passage wall surface and the temperature of the valve body become substantially equal,
Almost the entire machinable resin covering the outer peripheral edge of the valve body comes into contact with the inner wall surface of the through hole. As a result, as the valve element rotates about the axis of the through hole, the machinable resin covering the outer peripheral edge of the valve element is worn by the inner wall surface of the through hole. Can be

〔Example〕

1 and 2 show an overall view of a four-cylinder four-cycle internal combustion engine. Referring to FIGS. 1 and 2, 1 is a cylinder block, 2 is a piston, 3 is a cylinder head,
Reference numeral 4 denotes a combustion chamber, 5 denotes an intake valve, 6 denotes an intake port, 7 denotes an exhaust valve, 8 denotes an exhaust port, 9 denotes a fuel injection valve, and 10 denotes a spark plug. The intake valve 5 and the exhaust valve 7 are pressed against the cam 14 and the cam 15 by a compression spring 12 and a compression spring 13 for urging the intake valve 5 and the exhaust valve 7 in the valve closing direction. As the cams 14 and 15 rotate, the intake valve 5 and the exhaust valve 7 are opened and closed.

A housing 17 is fixed to the cylinder head 3, and four intake passages 18 are arranged in the housing 17 in parallel with each other, and the intake ports 6 of each cylinder are connected to the corresponding intake passages 18, respectively. A cylindrical through hole 20 extending in a direction substantially perpendicular to the intake passage 18 is formed across the four intake passages 18, and a rotary valve 22 that rotates around the axis of the through hole 20 in synchronization with the engine is provided with a through hole 20. Is inserted into. Both ends of the rotary valve 22 are rotatably supported by bearings 25, 26, 27 mounted in the housing 17. The rotary valve 22 includes four valve bodies 30 that open and close each intake passage 18.
Seal portions 31 are provided in the middle of the adjacent valve bodies 30 and outside the valve bodies 30 at both ends. The detailed structures of the valve body 30 and the seal portion 31 will be described later.

Next, the drive mechanism of the rotary valve 22 in the present embodiment will be described with reference to FIGS. Rotary valve 22
Is fixed to the drive pulley 33 via the adjustment piece 32.
The drive pulley 33 is connected to a camshaft pulley 35 via a timing belt 34, so that the rotary valve 22 rotates around the axis of the through hole 20 in synchronization with the camshaft. The rotary valve 22 is driven at half the rotational speed of the camshaft, that is, at one-fourth the rotational speed of the engine crankshaft in the case of a four-cycle internal combustion engine. That is, the rotary valve 22 is connected to the engine 1
Each cycle is rotated around the axis of the through hole 20 by 180 °.

In FIG. 2, the phase of the crank angle of each cylinder is delayed by 180 ° in the order of # 1, # 3, # 4, and # 2 cylinders, so that the intake stroke of each cylinder is also 180 ° in this order.
The phase is lagging each time. Therefore, the valve bodies 30 for controlling the opening and closing of the intake passages 18 of the respective cylinders are arranged on the rotary valves 22 with the phase shifted by 45 ° in the rotation angle of the rotary valve 22 in the above-described order, that is, each valve body 30 has a crank angle. Converted to 18
They are arranged with a phase shift of 0 °. The opening period of the intake valve 5 is a crank angle period of about 200 ° to about 240 °,
On the other hand, the valve opening period of the valve body 30 is slightly longer than the valve opening period of the intake valve 5. Therefore, when the valve body 30 opens before the intake valve 5 and closes after that, the intake timing and the intake period into the combustion chamber 4 are affected by the opening / closing control of the intake passage 18 by the valve body 30. Instead, it is controlled by the opening / closing timing of the intake valve 5.

Next, the configuration of the opening / closing valve timing adjusting means of the rotary valve 22 will be described with reference to FIGS. Rotary valve
Helical splines 22a and 33a are formed at opposite ends of the drive pulley 33 and the drive pulley 33, respectively, with twists in opposite directions. The helical splines 22a and 33a mesh with projections 32a and 32b formed on the inner peripheral surface of the adjustment piece 32, respectively, and by moving the adjustment piece 32 in the left and right direction in FIG. 3, the rotary valve 22 is driven. It is rotationally displaced with respect to the pulley 33, and thus the opening / closing timing of each intake passage 18 by each valve element 30 of the rotary valve 22 can be simultaneously changed for all cylinders by the same crank angle. The movement of the adjustment piece 32 in the axial direction is performed by swinging an adjustment lever 35 having one end fitted into an annular locking groove 32c formed on the outer peripheral surface of the adjustment piece 32. The adjusting lever 35 is configured such that an intermediate portion thereof can swing by a shaft 36, and the adjusting lever 35 is operated by an actuator 38. Actuator 38
Is controlled based on the output signal of the electronic control unit 40. The electronic control unit 40 is connected to an air flow meter 41 for generating an output signal indicating the engine intake air amount Q and a rotation speed sensor 42 for generating an output signal indicating the engine speed N.

In the electronic control unit 40, the engine load Q / N is calculated based on the output signals of the air flow meter 41 and the speed sensor 42, and the operation of the actuator 38 is controlled based on the engine load Q / N and the engine speed N, As a result, the opening / closing timing of each intake passage 18 by each valve element 30 of the rotary valve 22 is controlled. The optimum values of the operation amount of the actuator 38 for the engine load Q / N and the engine speed N are obtained in advance by experiments in the form of a map. If the opening period of the valve element 30 is shifted before the opening period of the intake valve 5 so that the rotary valve 22 opens and closes earlier than the intake valve 5, the engine intake stroke The intake passage 18 is closed by the valve body 30 in the middle of the process. As a result, adiabatic expansion of the intake air occurs in the combustion chamber 4 in the subsequent intake stroke, thus realizing a mirror cycle. By controlling the opening / closing timing of the valve element 30 of the rotary valve 22 in accordance with the engine operating state, the period during which the intake air flows into the combustion chamber 4 during one cycle of the engine is controlled. An appropriate intake air amount according to the operating state can be obtained. In this case,
Since the intake air is not restricted, substantially atmospheric pressure air is sucked into the combustion chamber 4 by lowering the piston, so that pumping loss is reduced.

Next, the structures of the valve element 30 and the seal portion 31 of the rotary valve 22 will be described with reference to FIGS. The rotary valve 22 includes a metal rotary valve base 45 and a machinable resin layer 46 covering almost the entire outer surface of the rotary valve base 45. In the present specification, the “resin that is easily worn” is referred to as “cuttable resin”. In the present embodiment, the machinable resin layer 46
Is a machinable resin composed of nylon and magnesium silicate, or a machinable resin composed of ionized ethylene fluoride, ethylene and carbon fiber (for example, Aflon COP
(Registered trademark)). The valve element 30 covered with such a machinable resin and farthest from the axis of the through hole 20
Almost the entire outer peripheral edge is formed so as to have an outer diameter larger than the inner diameter of the cylindrical through hole 20 when the rotary valve 22 is assembled and the temperature of the wall of the intake passage 18 and the temperature of the valve body 30 are substantially equal. You. Further, as described above, the rotary valve 22 has the seal portions 31 in the middle of the adjacent valve bodies 30 and outside the valve bodies 30 at both ends. In this seal portion 31, the rotary valve base portion
45 has a cylindrical shape, and is provided with an annular seal member 49 on the outer peripheral surface of the rotary valve base 45. The sealing member 49 is made of nitrile rubber, fluorine rubber, silicon rubber or the like. The seal member 49 is fixed to the above-described predetermined position of the rotary valve 22 by the machinable resin layer 46, and the seal member 49 leaks air between the adjacent intake passages 18,
Alternatively, leakage of air between the intake passage 18 and the outside of the housing 17 is prevented. Almost the entire outer peripheral surface of the seal portion 31 covered by the machinable resin layer 46 is attached to the rotary valve 22 when the temperature of the wall of the intake passage 18 and the temperature of the rotary valve 22 are substantially equal. It is formed so as to have a larger outer diameter. Usually, a seal member such as an O-ring is mounted in a groove formed on the outer peripheral surface of the shaft or the inner peripheral surface of the hole. On the other hand, in the present embodiment, air is formed by a simple structure in which the seal member 49 is fixed on the outer peripheral surface of the rotary valve base 45 by the machinable resin layer 46 without forming a groove on the outer peripheral surface of the rotary valve base 45. The feature is that the leakage of can be surely prevented.

When assembling the rotary valve 22 into the through-hole 20, the rotary valve 22 is contracted by a method such as cooling, and then the contracted rotary valve 22 is inserted into the through-hole 20.
Next, when the temperature of the wall surface of the intake passage 18 and the temperature of the rotary valve 22 become substantially equal, almost the entire outer peripheral edge of the machinable resin layer 46 covering the outer surface of the valve body 30 and the machinable resin layer 46 covering the outer surface of the seal portion 31 are formed. Almost the entire outer peripheral surface comes into contact with the inner wall surface of the through hole 20. Therefore, as the rotary valve 22 rotates around the axis of the through hole 20, the machinable resin layer 46 covering the outer peripheral edge of the valve body 30,
And the machinable resin 46 covering the outer peripheral surface of the seal portion 48
It is worn by the inner wall. Thus, the outer peripheral edge of the valve body 30 is rubbed against the inner wall surface of the through hole 20. As a result, the clearance between the outer peripheral edge of the valve body 30 and the inner wall surface of the through hole 20 can be made extremely small, and therefore, when the valve body 30 is closed, the intake passage 18 can be properly closed.
The engine intake air amount can be accurately controlled. Similarly, the outer peripheral surface of the machinable resin layer 46 of the seal portion 31 is
It is rubbed against the inner wall. As a result, the clearance between the outer peripheral surface of the machinable resin layer 46 of the seal portion 31 and the inner wall surface of the through-hole 20 can be made very small, whereby the airtightness secured by the seal member 49 can be more reliably ensured. Can be something.

Cylindrical through holes for multi-cylinder internal combustion engines with long engine lengths
In order to form the through hole 20, it is necessary to form the through holes 20 from both sides of the housing 17. In this case, it is difficult to ensure good cylindricity of the through hole 20 as shown in FIG. 6A, and a step is formed in the through hole 20 as shown in FIGS. 6B and 6C. Often, the straightness of the through-hole 20 is deteriorated. However, in this embodiment, the rotary valve 22
The outer peripheral surface of the valve body 30 and the outer peripheral surface of the seal portion 31 are made of a machinable resin layer.
As shown in FIGS. 6 (b) and 6 (c), even when the cylindricity of the through hole 20 is not good, the machinable resin layer 46 is covered with the through hole 20 as described above. The rotary valve 22 can be assembled because it is worn by the wall surface, and the clearance between the outer peripheral edge of the valve body 30 and the through hole 20 and the clearance between the outer peripheral surface of the machinable resin layer 46 and the through hole 20 in the seal portion 31 are provided. Can be reduced as much as possible.

Next, a method of manufacturing the rotary valve 22 will be described with reference to FIG. First, as shown in FIG. 7A, the rotary valve base 45 is formed by casting or forging. Next, as shown in FIG. 7B, the seal member 49 is mounted on the rotary valve base 45. Next, as shown in FIG. 7 (c), the rotary valve base 45 on which the seal member 49 is mounted is placed in a mold, and the outer surface of the rotary valve base 45 is coated with a machinable resin layer 46 by injection molding. Let me know. As a result, the seal member 49 is fixed to the rotary valve base 45. Next, as shown in FIG. 7 (d), the shafts supported in the bearings 25, 26, 27, the helical splines 22a, and the outer peripheral edge of the machinable resin layer 46 are machined. It is to be noted that substantially the entire outer peripheral edge of the valve element 30 covered with the machinable resin layer 46 and farthest from the rotation axis of the rotary valve 22 and almost the entire outer peripheral surface of the machinable resin layer 46 of the seal portion 31 are rotary. At the time of assembling the valve 22, when the temperature of the wall of the intake passage 18 and the temperature of the rotary valve 22 are substantially equal, the outer peripheral edge of the machinable resin layer 46 is mechanically adjusted so that it has an outer diameter larger than the inner diameter of the through hole 20. Processed.

Next, another embodiment shown in FIG. 8 will be described. 8th
The figure shows a rotary valve 22 in a six-cylinder four-cycle internal combustion engine.
In this embodiment, a central portion of the lens is held by a bearing 52. The portion of the rotary valve 22 held by the bearing 52 is not covered with the machinable resin, and this portion is formed by machining the rotary valve base 45. In the case of such a multi-cylinder internal combustion engine having a long engine length, the rotary valve 22
By holding the center of the rotary valve 22 with the bearing 52, the bending of the rotary valve 22 is reduced, so that it is not necessary to provide a joint in the middle of the rotary valve 22 or to divide the rotary valve 22. In the embodiment shown in FIG.
Although only one bearing 52 is provided at the center of the 22, the bearing 52 may be provided at a plurality of locations between any adjacent intake passages 18. The bearing 52 can be provided at an intermediate portion of the rotary valve 22 not only in the six-cylinder internal combustion engine but also in a four-cylinder internal combustion engine or the like.

〔The invention's effect〕

As the valve body rotates around the axis of the through hole, almost the entire outer surface of the machinable resin layer covering the outer peripheral edge of the valve body farthest from the axis of the through hole is worn by the inner wall surface of the through hole, that is, the outer peripheral edge of the valve body penetrates. Since it is rubbed against the inner wall surface of the hole, the clearance between the outer peripheral edge of the valve body and the inner wall surface of the through hole can be made very small. Therefore, the intake passage can be satisfactorily closed when the valve body is closed, so that the engine intake air amount can be accurately controlled.

[Brief description of the drawings]

1 is a sectional view taken along line II of FIG. 2, FIG. 2 is an overall view of a four-cylinder four-cycle internal combustion engine, FIG. FIG. 4 shows the second
FIG. 5 is an enlarged cross-sectional view taken along the line IV-IV in FIG. 5, FIG. 5 is an enlarged cross-sectional view of a portion indicated by an arrow V in FIG. 4, FIG. FIG. 8 is a view for explaining a manufacturing process of a rotary valve, and FIG. 8 is an overall view of a six-cylinder four-cycle internal combustion engine showing another embodiment. 18 ... intake passage, 20 ... through hole, 30 ... valve body, 46 ... cutable resin layer.

Claims (1)

(57) [Claims] A cylindrical through-hole is formed substantially perpendicularly to the axis of the intake passage and penetrates the intake passage, and a valve element which rotates around the axis of the through-hole in synchronization with the engine is inserted into the through-hole. In the intake control apparatus wherein the intake passage is controlled to be opened and closed by the valve body, the entire outer surface of the valve body is covered with the machinable resin, and the valve covered with the machinable resin and farthest from the through-hole axis. Almost the entire outer peripheral edge of the valve body is formed at the time of assembling the valve element and has an outer diameter larger than the inner diameter of the through hole when the temperature of the intake passage wall surface and the temperature of the valve element are substantially equal to cover the outer peripheral edge of the valve element. An intake control device for an internal combustion engine in which substantially the whole of the machinable resin contacts the inner wall surface of the through hole.