JPH0231542Y2 - - Google Patents

Description

[Detailed description of the invention] The present invention has a subchamber connected to the exhaust passage of an internal combustion engine through a branch passage, and the branch passage is opened in a low speed operating range of the engine and closed in a high speed operating range. The present invention relates to an exhaust subchamber device equipped with an on-off valve.

This type of exhaust subchamber device lowers the natural frequency of the exhaust passage by opening the on-off valve and putting the subchamber into operation, thereby creating an elongated state of the exhaust passage and producing a pulsating effect within the exhaust passage. by adapting it to the engine's low-speed operating range, and by closing the on-off valve and rendering the subchamber inactive.
By increasing the natural frequency of the exhaust passage, the exhaust passage becomes as if it were shortened, and the pulsation effect in the exhaust passage is adapted to the high-speed operating range of the engine, thereby making the pulsation effect of the exhaust passage effective over the entire operating range. This can be used to enhance the engine's suction effect and improve its output performance.

Conventionally, as an exhaust subchamber device for providing such an effect, a so-called Helmhuitz type subchamber device is known, which has a structure in which a subchamber provided in the middle of an exhaust path is connected via a branch path having a certain required length. However, in this type of subchamber device, the entire subchamber inevitably becomes longer by the length of the branching path, which makes it difficult to make it compact. Incidentally, the present applicant has already proposed an exhaust system control device for an internal combustion engine (Japanese Patent Application No. 57-223414) as an invention relating to the close relationship between the exhaust path and the branch path.

The present invention was made in consideration of the above problems, and a partition wall for forming a branch path is provided in the subchamber on the subchamber side of the on-off valve, thereby ensuring the required length of the branch path. By shortening the overall length of the subchamber above, the subchamber can be made more compact, and by placing the subchamber and branch passages close to the water jacket of the internal combustion engine, the influence of exhaust heat can be suppressed and design conditions can be set. An object of the present invention is to provide an exhaust subchamber device that facilitates this.

Hereinafter, the present invention will be explained based on an embodiment shown in the attached FIGS. 1 to 4. The embodiment shown in the figure is
This figure shows an example of application to a water-cooled two-stroke internal combustion engine. In these figures, numeral 1 is a crankcase, 2 is a cylinder attached to this crankcase 1, and 3 is a cylinder head attached to this cylinder 2. . A spark plug 4 is attached to the cylinder head 3, and a piston 5 within the cylinder 2 is connected via a connecting rod 8 to a crankshaft 7 rotatably supported by the crankcase 1. A water jacket 9 is formed around the outer periphery of the cylinder 2, and a head cover 10 attached to the cylinder head 3 is formed with an inlet passage 10a and an outlet passage 10b that communicate with the water jacket 9. Furthermore, a cap 11 is attached to the head cover 10, which communicates with the outlet passage 10b, and one end of a pipe for communicating with a radiator (not shown) is attached to the cap 11. In FIG. 1, 12 indicates a scavenging port, and 13 indicates an exhaust port.

FIG. 2 shows a vertical cross-sectional view of the main part taken in a direction approximately 90 degrees different from that in FIG. Subchambers 14 are formed in close proximity. Furthermore, a branch passage 15 is formed in the cylinder 2 to allow the subchamber 14 and the exhaust port 13 to communicate with each other. This branch path 15 is composed of a horizontal path 15a extending outward in the radial direction of the cylinder 2, and a vertical path 15b extending from the horizontal path 15a into the subchamber 14. and a partition wall 17 protruding into the subchamber 14, so that the vertical passage 15b is substantially located within the subchamber 14 and closest to the water jacket 9. This is taken into consideration. Note that the protrusion length h of the partition wall 17 is the same as that of the subchamber 14.
In order to fully demonstrate the function of the subchamber 14, the required length of the branch passage 15, its cross-sectional area, etc. are taken into account and determined as appropriate.

Horizontal path 15a and vertical path 15b of the branch path 15
An on-off valve A for opening and closing the branch path 15 is provided at the intersection. That is, the cylinder 2 has a valve mounting hole 1 coaxially formed with the horizontal passage 15a, which communicates with the horizontal passage 15a from the outside, and a bearing 19 that also functions as a closing member for the mounting hole. A rod 20 is slidably inserted through the rod 20, and a valve body 22 is provided at the inner end of the rod 20 to open and close a valve seat 21 formed in the horizontal passage 15a. A link mechanism B for reciprocating the rod 20 in its axial direction is connected to the outer end of the rod 20. The link mechanism B includes a fixed shaft 2 positioned at a fixed position via a support member 23 fixed to the crankcase 1 etc.
4, and sleeves 25a and 2 are attached to this fixed shaft 24.
6a, the drive arm 25 and the actuation arm 26 are provided rotatably around the fixed shaft 24, respectively.
5 and 26 are arranged to form an L-shape when viewed from the axial direction of the fixed shaft 24, as shown in FIG. Of these two arms 25 and 26, one operating arm 26 has a pin 27 attached to the outer end of the rod 20.
The other drive arm 25 is connected via a wire 29 to a switching pedal 28 disposed at a position where it can be touched by a foot or the like, as shown in FIG. 4, for example. A coil-shaped connection spring 30 is inserted between the two arms 25 and 26 to connect the two arms by fixing one end to the drive arm 25 and the other end to the actuation arm 26. An operating arm 26 is provided between the supporting member 23 and the supporting member 23.
A coil-shaped torsion spring 31 is inserted which urges the valve body 22 toward the right in FIG. 2, that is, in a direction in which the valve body 22 closes the valve seat 21. In addition, in the figure, 3
2 is a vehicle body, 33 is an engine, and 34 is an exhaust muffler.

In the exhaust subchamber device configured as described above, a partition wall 17 is provided on the subchamber 14 side of the on-off valve B, a part of the branch passage 15 is located inside the subchamber 14, and further below the tip of the partition wall 17. Since the structure is such that the space 14' formed in the subchamber 14 is also used as a part of the subchamber 14, the space required for providing the subchamber 14 can be used efficiently, and therefore, unlike the conventional
The entire subchamber does not become longer or protrude excessively by the length of the branch path, resulting in a compact structure as shown. Further, in the embodiment, the subchamber 14 includes a partition wall 16
Since the vertical path 15b, which is a part of the branch path 15, is also provided in a similar manner close to the water jacket 9, various conditions must be taken into account. This makes it easier to set the design conditions for the subchamber 14 designed as follows. In other words, it is known that the natural frequency of exhaust pulsation changes depending on the temperature, but since the water jacket 9 is thermally stable, the subchamber 14 and vertical The passage 15b is also thermally stabilized by the action of the water jacket 9 and is less susceptible to the effects of exhaust heat, and therefore the temperature change is small, making it easier to set design conditions.

Here, to explain the operation related to the on-off valve A and the link mechanism B, when the engine 33 reaches the high-speed operating range and the driver depresses the switching pedal 28, the drive arm 25 is switched to the second position via the wire 29. In the figure, the actuating arm 26 is also rotated in the direction of arrow A via the connecting spring 30, and as a result, the rod 20 slides and leans against the valve body 22. The valve seat 21 is closed and the subchamber 14 is inactive. Note that when the engine 33 reaches the low speed operating range, if the operation of the switching pedal 28 is stopped, both the drive arm 25 and the operating arm 26 return to their original positions, the valve seat 21 is opened, and the subchamber 14
becomes the active state.

As explained above, in the present invention, a subchamber is connected to the exhaust passage of an internal combustion engine via a branch passage, and the branch passage is opened in a low-speed operating range of the engine and closed in a high-speed operating range. In an exhaust subchamber device provided with an operating on-off valve, the subchamber is provided alongside a water jacket formed in an internal combustion engine via a partition, and the branch passage is connected to a part of the partition and within the subchamber. It is characterized by being formed by a protruding partition wall, and it is possible to make the subchamber more compact by shortening the overall length of the subchamber while ensuring the required length of the branch path. In addition, by placing the subchamber and the branch path close to the water jacket, it has excellent effects such as thermally stabilizing the subchamber and the branch path, making it easier to set these design conditions. play.

[Brief explanation of the drawing]

Figures 1 to 4 show an embodiment of the present invention. Figure 1 is a partially omitted vertical cross-sectional view showing an example in which the present invention is applied to a water-cooled two-stroke internal combustion engine, and Figure 2 is a partially omitted longitudinal cross-sectional view showing an example in which the present invention is applied to a water-cooled two-stroke internal combustion engine. FIG. 3 is a cross-sectional view of the link mechanism, and FIG. 4 is a schematic plan view of the motorcycle. 13...exhaust port, 14...subchamber,
15... Branch road, 17... Partition wall, A... On-off valve.

Claims (1)

[Scope of utility model registration request] In the exhaust subchamber device, a subchamber is connected to the exhaust path of an internal combustion engine via a branch path, and the branch path is provided with an on-off valve that opens in a low speed operating range of the engine and closes in a high speed operating range. A subchamber is attached to a water jacket formed in an internal combustion engine via a partition wall, and the branch passage is formed by a part of the partition wall and a partition wall protruding into the subchamber. An exhaust subchamber device characterized by: