JPH02301621A - Port timing adjuster of internal combustion engine - Google Patents

Abstract

PURPOSE:To enable assembling of a rotation body which is an integral molding to a cylinder by cutting off a part of a section which is other than a movable wall of an end part of the revolution body and overlaps with a convex part of the cylinder viewed from the axial direction. CONSTITUTION:In a rotation body 8, a section which is other than a movable wall 8c of one end of a valve body 8a and overlaps with a convex part 1b of a cylinder viewed from the axial direction of the rotation body 8 is cut off. By this, when a cut off part 8f is pushed into a storage chamber 7 from the cut off part 8f so that it faces the convex part 1b of the cylinder 1, as the cut off part 8f can pass the convex part 1b without interfering with it, the rotation body 8 can be easily integrated into the storage chamber 7. And after the rotation body 8 is integrated, the rotation body 8 is rotated by half about 180 deg. in the storage chamber 7. As the integrated molded rotation body 8 can be assembled to the cylinder 1 in this way, reduction in the number of working processes, cost reduction, improvement in assembly performance and reduction in the number of parts can be achieved.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention changes the opening/closing timing of the port (port timing) by rotating a rotating body provided near the port opening on the inner surface of the cylinder. The present invention relates to a variable port timing device for an internal combustion engine.

(Prior Art) As a conventional example of this type of port timing variable device, an exhaust port timing variable device is shown in FIG.
417 is a plan sectional view of the exhaust port timing variable device, in which 10B is the exhaust port 1 of the cylinder 101.
A rotating body (rotary valve) is rotatably supported at the upper part near the cylinder 101, and is housed in an elliptical housing chamber 107 formed in the cylinder 101. still,
A movable wall 108C is formed on the rotating body 108 and functions as an upper edge of the exhaust port 104a.

The exhaust port 104a is opened and closed by a piston (not shown) that moves up and down on the inner surface of the cylinder 101a, and the exhaust port timing device 3 rotates the rotating body 108 according to the output, rotational speed, etc. of the engine. By moving the rotary body 108, the movable wall 108c of the rotating body 108 moves up and down the exhaust port 104a, thereby causing the exhaust port 104a to move up and down.
The opening/closing timing (port timing) can be changed.

By the way, in order to effectively and appropriately change the port timing by rotating the rotating body 108, it is necessary to bring the rotating body 108 as close as possible to the cylinder inner surface 1.01a.
Therefore, the movable wall 108c of the rotating body 108 inevitably becomes a drum-shaped concave curved surface along the curvature of the cylinder inner surface 101a. A convex portion 101b is formed.

If the rotating body 108 is integrally molded due to the above-mentioned circumstances, even if the rotating body 108 is to be passed from one direction of the accommodation chamber 107 when it is assembled to the cylinder 101, the rotating body 108
The large diameter portion 108f (or to, sg) of 08 cannot pass through the convex portion 101b of the cylinder 101, and the rotating body 108 cannot be assembled to the cylinder 101 after all.

Therefore, as shown in FIG. 1, the rotating body 108 is
It is divided into two parts 108-1 and 108-2 at the minimum diameter part of c, and when assembling each part 108-1, 10
8-2 is installed separately in the accommodation chamber 107, the one-car split piece 108-1°IQ8-2 is positioned using a pin 115, and then integrated by tightening with a bolt 116 (Jikkosho). 58-5063).

(Problems to be Solved by the Invention) However, when the rotating body 10B is divided into two parts as described above, processing of the rotating body 108 is troublesome and increases the number of processing steps, and the assemblability of the rotating body 108 becomes difficult and the number of parts increases. The problem arises that it increases. or.

A step inevitably occurs on the base surfaces of the divided pieces 108-1 and 108-2, and this step causes a shift in port timing, which also causes a problem that engine performance is impaired.

The present invention has been made in view of the above problems, and its purpose is to reduce the number of man-hours for machining the rotating body and reduce costs by making it possible to assemble the rotating body, which is an integrally molded product, to the cylinder. It is an object of the present invention to provide a port timing variable device for an internal combustion engine that can improve assemblability and reduce the number of parts, as well as eliminate deviations in port timing and prevent deterioration of engine performance.

(Means for Solving the Problems) In order to achieve the above object, the present invention forms a storage chamber in the vicinity and upper part of a gas passage formed in a cylinder or a port that opens on the inner surface of the cylinder, and in the storage chamber, a gas passage formed in a cylinder or a port opening into the inner surface of the cylinder is provided with a storage chamber. A device rotatably houses a rotary body having a movable wall functioning as an upper edge, and changes port timing by raising and lowering the movable wall by rotation of the rotary body, the rotary body The movable wall is composed of a drum-shaped curved surface, and
A variable port timing device for an internal combustion engine, wherein a portion of the cylinder has a convex portion to which a movable wall of the rotary body is fitted, wherein the cylinder has a portion other than the movable wall of at least one end of the rotary body. , and is characterized in that at least a portion of a portion that overlaps with the convex portion of the cylinder when viewed from inside the rotary body in the axial direction is removed.

Further, in the variable port timing device for an internal combustion engine, the present invention provides a method in which a convex portion of the cylinder is removed leaving only a part, and a hole is formed that includes a curved surface of the remaining convex portion, and Its feature is that it has a through hole that can be penetrated.

(Function) According to the first invention, even if the rotating body is integrally molded, the rotating body can be inserted in the axial direction from one side of the storage chamber when assembling the rotating body into the cylinder. That is, if the rotating body is inserted into the storage chamber with the cutout formed at at least one end of the rotating body first, the cutout can pass through the protrusion of the cylinder without interfering with it, so it is an integral molding amount. The rotating body can be easily assembled into a cylinder.

In this case, the movable wall portion of the rotating body is not subjected to any special processing for assembly, so that the sealing performance at the fitting portion between the movable wall and the convex portion of the cylinder is not impaired.

Further, according to the second aspect of the invention, the rotating body, which is integrally molded, can be easily assembled into the cylinder.

That is, since the cylinder has a through hole through which the rotating body can pass, the rotating body can be passed through the through hole first, and then the rotating body can be set in the correct position relative to the storage chamber. In this case, the rotating body is not specially processed for assembly, and a part of the convex part of the cylinder is left uncut, so it is difficult to fit the remaining convex part with the movable wall of the rotating body. The sealing performance at the mating part is not impaired.

As described above, according to the present invention, it is possible to easily assemble the rotary body, which is an integrally molded amount, into the cylinder, so that the assemblability of the rotary body is improved, and its processing is facilitated, reducing the number of man-hours required for machining it. In addition, it is possible to reduce the number of parts and reduce costs, and it is also possible to eliminate port timing deviations and prevent deterioration in engine performance.

(Example) An example of the first invention will be described below based on the accompanying drawings.

Figure 1 is a plan view of the rotating body, Figure 2 is a view in the direction of arrow A in Figure 1, Figure -3 is a view in the direction of arrow B in Figure 1, and Figure 4 is a view in the direction of arrow B in Figure 1.
Figure 5 is a vertical cross-sectional view of the cylinder, Figure 6 is a cross-sectional view taken along the VT-Vl line in Figure 5, and Figures 7 to 11 show how to assemble the rotating body. FIG. 12 is a longitudinal sectional view of the upper part of the engine cylinder in a state where the rotating body is assembled, and FIG. 13 is a sectional view taken along a single layer line in FIG. 12.

The configuration of the variable port timing device according to the present invention will be explained based on FIG. 12. In the figure, l is a cylinder of a two-stroke engine, and a cylinder head 2 is attached to the upper part of the cylinder. . A piston 3 is fitted into the cylinder l so as to be able to slide up and down.
A main exhaust passage 4, a sub-exhaust passage 5.5 (see Fig. 6), and a scavenging passage 6 are formed in the cylinder, and these are connected to a main exhaust port 4a and a sub-exhaust bow, respectively, on the inner surface of the cylinder 1a.
-5a, 5a, scavenging ports 6a, . . . are opened. The two sub-exhaust passages 5, 5 merge into the main exhaust passage 4, and the main exhaust passage 4 is connected to an exhaust pipe (not shown). The scavenging bows 6a open into a crank chamber (not shown) formed below the cylinder l.

By the way, in the upper part of the main exhaust passage 4 of the cylinder l near the main exhaust port 4a, there is a circular hole-shaped housing whose lower half opens into the main exhaust passage 4, as shown in detail in FIGS. 5 and 6. A chamber 7 extends perpendicularly to the plane of the paper in FIG. 5, and a rotating body (rotary valve) 8, the details of which are shown in FIGS. has been done.

The rotating body 8 is an integrally molded product obtained by aluminum casting, and as shown in FIGS. 1 and 4, the center portion thereof constitutes a valve body 8a.
In the center of the valve body 8a, a concave groove-shaped exhaust passage 8b, which constitutes a part of the main exhaust passage 4, is formed over an angle range of approximately 1800 degrees, and in the remaining part of the valve body 8a, a drum-shaped concave groove is formed. A movable wall 8C having a curved surface is formed. The bottom surface 8b-1 of the exhaust passage 8b is formed flat, and the movable wall 8c is formed into a concave curved surface that follows the curvature of the cylinder inner surface 1a. teeth,
This is to bring the rotating body 8 as close to the cylinder inner surface la as possible. Further, journal portions 8d and 8e are formed on both sides of the valve body 8a of the rotating body 8.

On the other hand, the angle θ shown in FIG. 5 is formed at the center of the portion of the upper half wall of the storage chamber 7 of the cylinder 1.

A convex portion 1b having a convex curved surface protrudes into the storage chamber 7 over a range of , and the movable wall 8C of the rotating body 8 is tightly fitted into the convex portion 1b. Therefore, the central portion of the upper half of the storage chamber 7 is constricted into a drum shape as shown in FIG.

Therefore, in this embodiment, FIG. 1, FIG. 2, and FIG.
As shown in the figure, a portion of the rotating body 8 excluding the movable wall 8c at one end of the valve body 8a, and a portion overlapping with the convex portion 1b of the cylinder 1 when viewed in the axial direction of the rotating body 8 (see FIG. 2). The left side portion (cutout portion) 8f of the exhaust passage 8b of the valve body 8a in FIG. It is also formed to have a small diameter. In addition, the chain line in FIG. 2 shows the shape before cutting.

When the cutout 8f is formed at one end of the rotating body 8 as described above, the rotating body 8, which is integrally molded, can be easily assembled into the housing chamber 7 of the cylinder 1 in the following manner.

That is, as shown in FIGS. 7 and 8, the rotating body 8 is inserted into the storage chamber 7 from the cutout 8f side with its cutout 8f facing the convex portion 1b of the cylinder 1, as shown by the arrow in FIG. If pushed in the direction, the cutout portion 8f can pass through the convex portion 1b of the cylinder 1 without interfering with the convex portion 1b.
can be easily incorporated into the housing chamber 7 of the cylinder l. After the rotating body 8 is assembled, the rotating body 8 is placed in the housing chamber 7 by approximately 18 mm as shown in FIGS. 10 and 11.
When rotated by 0° and a half, the cutout 8f of the rotating body 8 faces into the main exhaust passage 4 as shown in the figure, and the movable wall 8C tightly fits into the protrusion 1b of the cylinder 1, and the movable wall 8c and the movable wall 8c fit tightly together. The fitting portion with the convex portion 1b is completely sealed.

Note that the cutout portion 8f is located at the convex portion 1 of the cylinder 1 of the rotating body 8.
The resection portion 8f may be obtained by resecting all of the region that overlaps b in the axial direction, or may be formed by partially resecting a part of the overlapping region. In this case, as shown in FIG. 9, the rotating body 8 is
If the rotating body 8 is pushed into the housing chamber 7 while being tilted relative to the housing chamber 7, the cutout part 8f can pass through the convex part ib of the cylinder l without interfering with it.
It can be easily incorporated into the system.

As described above, in this embodiment, since the rotary body 8, which is an integrally molded amount, can be easily assembled into the cylinder XC, the assemblability of the rotary body 8 is improved, and its processing is facilitated. It is possible to reduce the number of processing steps and the number of parts, and reduce costs.

After the rotary body 8 is assembled into the accommodation chamber 7 of the cylinder 1 in the manner described above, the rotary body 8 is fitted into its journal portions 8d, 8e or both ends of the accommodation chamber 7, as shown in FIG. It is rotatably supported by a bearing 9°10. A pulley 11 is connected to one end of this rotating body 8 by a bolt 12, and a boot 11 is connected to a wire 1.
3 to a servo monitor (not shown).

Note that the servo motor operates according to the rotational speed and output of the engine, and connects the rotating body 8 via the wire 13 and pulley 11.
is rotated by a predetermined angle in a predetermined direction.

The one-rotating body 8 is rotated by the servo motor between an upper position shown by a solid line and a lower position shown by a chain line in FIG. The opening timing of the main exhaust bow 4a is advanced, and as the movable wall 8C protrudes downward, the opening timing of the main exhaust bow 4a is substantially delayed. In this case, the rotating body 8 is an integrally molded product, and unlike the conventional two-part type, there is no step on the movable wall 8c, so the main exhaust port 4a
There is no deviation in the opening/closing timing (port timing) of the engine, and deterioration in engine performance due to port timing deviation is prevented.

Next, an embodiment of the second invention will be described based on FIGS. 14 to 16. Note that Fig. 14 is a plan view of the rotating body, and Fig. 15 is a plan view of the rotating body.
The figure is a vertical cross-sectional view of the cylinder, and Figure 16 is E-E in Figure 15.
These are line sectional views, and in these figures, the same elements as shown in the embodiment according to the first invention are denoted by the same reference numerals, and the description thereof will be omitted hereinafter.

In this embodiment, the rotary body 8, which is integrally molded, is not subjected to any special processing for assembly, and a through hole 14 through which the rotary body 8 can pass is formed on the cylinder l side. It is provided through the housing chamber 7 at a position offset by a predetermined amount. This through hole 14 is a circular hole whose center is at a position 02 eccentric by ε with respect to the center 01 of the storage chamber 7, and a portion 14a (portion with an arc length S) of the through hole 14 is located at the convex portion 1b of the cylinder 1. It is made up of some parts. Therefore, this through hole 14 is formed by leaving a part of the convex part 1b of the cylinder l (hatched part C in FIG. 15) and cutting out the other part (hatched part d in FIG. 15).

The rotating body 8 is assembled into the cylinder 1 in the following manner.

That is, first, the rotating body 8 is passed through the through hole 14 of the cylinder 1 as shown by the chain line in FIG. The rotating body 8 is moved so that its axial center 02 coincides with the center 01 of the housing chamber 7, and the rotating body 8 is housed in the housing chamber 7.
is rotatably supported by a bearing (not shown). At this time, since the convex part ib of the cylinder l remains as it is within the length S, the convex part ib and the movable wall 8 of the rotating body 8
The fit with C is tight, and high sealing performance is ensured between the two. Incidentally, a spacer may be fitted later into the cut out portion d of the convex portion ib of the cylinder 1 (see FIG. 15).

In this way, also in this embodiment, since the rotating body 8, which is an integrally molded product, can be easily incorporated into the cylinder l,
Effects similar to those obtained in the embodiment according to the first invention can be obtained.

In the above description, the present invention is particularly applied to a variable exhaust port timing device for a two-stroke engine, but the present invention can be applied to any other variable port timing device.

(Effects of the Invention) In a variable port timing device for an internal combustion engine, a portion excluding a movable wall at at least one end of a rotating body,
In addition, at least a part of the part that overlaps with the convex part of the cylinder when viewed in the axial direction of the rotating body is removed, or the convex part of the cylinder is removed with only a part of it remaining, including the curved surface of the remaining convex part. Since the through-hole is drilled through which the rotating body can pass through, the integrally molded rotating body can be assembled into the cylinder, reducing the number of man-hours required for machining the rotating body, reducing costs, and improving ease of assembly. It is possible to improve the performance and reduce the number of parts, and also to eliminate port timing deviations and prevent deterioration of engine performance.

[Brief explanation of the drawing]

FIG. 1 is a plan view of the rotating body according to the first invention, and FIG. 2 is a plan view of the rotating body according to the first invention.
3 is a view in the direction of arrow A in the figure, FIG. 3 is a view in the direction of arrow B in FIG. Figure 6 is a sectional view taken along the line ■-■ in Figure 5, and Figure 7.
Figures 1 to 11 are explanatory diagrams showing how to assemble the rotating body.
Figure 2 is a vertical sectional view of the upper part of the engine cylinder with the rotating body assembled, and Figure 13 is the I-XOI of Figure 12.
A line sectional view, FIG. 14 is a plan view of the rotating body according to the second invention,
FIG. 15 is a vertical sectional view of a cylinder showing the second invention, and FIG.
The figure is a sectional view taken along the line E--E in FIG. 15, and FIG. 17 is a plan sectional view showing a conventional variable port timing device. 1... Cylinder, la... Cylinder inner surface, lb...
・Protrusion, 4... Main exhaust passage (gas passage), 4a...
Main exhaust port (port), 7... Accommodation chamber, 8... Rotating body. 8C...Movable wall, 14...Through hole. Patent Applicant: Yamaha Motor Co., Ltd. Agent Patent Attorney Ryo Yamashita - Figure 1 R - 7 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 Figure 14 Figure 15 Figure 16

Claims (2)

[Claims] (1) A storage chamber is formed in the upper part near the port where the gas passage formed in the cylinder opens to the inner surface of the cylinder, and a rotating body provided with a movable wall that functions as the upper edge of the port is rotatable in the storage chamber. The apparatus is configured to change the port timing by raising and lowering the movable wall according to the rotation of the rotating body, the movable wall of the rotating body being configured with a drum-shaped curved surface, and one part of the cylinder In a variable port timing device for an internal combustion engine, the port timing variable device for an internal combustion engine is formed with a convex portion into which a movable wall of the rotating body is fitted, the portion excluding the movable wall at at least one end of the rotating body,
A variable port timing device for an internal combustion engine, characterized in that at least a portion of a portion that overlaps the convex portion of the cylinder when viewed in the axial direction of the rotary body is removed. (2) A storage chamber is formed in the vicinity and upper part of the port where the gas passage formed in the cylinder opens to the inner surface of the cylinder, and a rotating body provided with a movable wall that functions as the upper edge of the port is rotatable in the storage chamber. The apparatus is configured to change the port timing by raising and lowering the movable wall according to the rotation of the rotating body, the movable wall of the rotating body being configured with a drum-shaped curved surface, and one part of the cylinder In a variable port timing device for an internal combustion engine, the port timing variable device for an internal combustion engine is formed with a convex portion into which a movable wall of the rotating body is to be fitted, in which the convex portion of the cylinder is removed leaving only a part of the convex portion, and the remaining convex portion is removed. 1. A variable port timing device for an internal combustion engine, comprising a through hole having a curved surface and through which the rotating body can pass.