JPS599055Y2 - Internal combustion engine intake inertia pipe - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement of an intake inertia pipe that improves the intake inertia effect in an internal combustion engine.

Conventionally, in an internal combustion engine, an intake inertial pipe connected to an intake port provided in a cylinder head to introduce intake air is used, for example, in a multi-cylinder engine, each intake pipe is an independent intake system, and each intake pipe is It is known that it is effective to improve the intake inertia effect and increase the volumetric efficiency by setting the lengths to be equal and to the optimal length within the constraint range around the setting position. .

As a means for obtaining the optimal intake pipe length according to the rotational speed, for example, as shown in Japanese Patent Application Laid-Open No. 47-35614, a pipe length that can freely go in and out of the suction side of the intake pipe is used. Some engines are equipped with an adjustment pipe, and the pipe length adjustment pipe is moved in and out in conjunction with changes in engine speed, so that the optimal intake pipe length according to the engine speed can be automatically obtained.

With this type of structure, high output can be automatically obtained over a wide range of rotations from low to high speeds, and the maximum torque can be maintained at all times in response to constant torque changes during fishing and work. However,
If it is attempted to perform adjustment from high speed rotation to low speed rotation range using this tube length adjustment tube, the range in which the tube length adjustment tube moves in and out, that is, the sliding range will naturally become longer.

On the other hand, in a structure provided with such an intake inertia pipe,
It has the disadvantage of increasing noise due to air column vibration in the intake pipe,
For this purpose, it is necessary to provide an expansion chamber with an intake silencer at the inlet end of the intake inertial pipe.

In this case, if a pipe length adjustment pipe is provided, the pipe length adjustment pipe will be placed inside this intake silencer, but as mentioned above, the entire range from low speed to high speed can be controlled by moving in and out of the pipe length adjustment pipe. In a device in which the output is adjusted to the maximum, there is a drawback that sufficient space cannot be taken for the entrance and exit of the pipe length adjustment pipe unless the intake silencer is made larger than necessary.

The present invention solves these drawbacks by limiting the range of automatic adjustment of the intake pipe length by the pipe length adjustment pipe to the medium speed rotation range that is most often used when working on fishing boat engines, etc., thereby improving the pipe length. On the other hand, in order to shorten the inlet and exit range of the adjustment pipe as much as possible, and on the other hand, for high-speed rotations that are widely used, it is possible to form another short intake passage by branching the intake pipe, and to install a shirt tab at the branch part. Accordingly, the intake passage can be switched between high speed and medium speed, thereby making it possible to have a compact structure as a whole without increasing the size of the intake silencer.

The structure of the present invention will be explained as follows based on a drawing showing an embodiment implemented in a three-cylinder internal combustion engine.

First, in FIGS. 1 and 2, each intake pipe 1, 1, 1, which is designed to be independent and have the same length, has one end in each cylinder 2a, 2 provided in the cylinder head.
A fixed pipe is connected to an intake port (not shown) of b, 2C, its tip is allowed to hang down while avoiding the fuel pump 3 and generator 4, and is inserted into an intake silencer 6 having an intake hole 5. In this way, the fixed pipe 7 constitutes a part of the intake pipe 1.

Thus, the fixed pipe 7 is provided with a branch pipe 8 in the middle thereof, and is branched in two directions.
As shown in the figure, a switching shirt 10 fixed to the switching shaft 9 is installed inside, and the switching shirt 10 allows a long main suction passage 11a on the fixed pipe 7 side and a short sub suction passage on the branch pipe 8 side. 11b can be selectively opened.

Furthermore, in FIG. 3, a switching shaft rotation lever 12 is fixedly attached to the shaft end of the switching shaft 9 that protrudes from the intake silencer 6, and the switching shaft rotation lever 12 is rotated to rotate the switching shutter 10.
This can be done automatically by linking the rotary lever 12 to the rod 14 of a solenoid valve 13 and operating the solenoid valve 13 according to the engine speed. can.

Next, as shown in FIG. 2, a tube length adjusting tube 15 is slidably fitted onto the open end of the fixed tube 7, and the tip of the tube length adjusting tube 15 protrudes outward from the fixed tube 7. It has a trumpet-shaped opening.

Reference numeral 16 denotes a connecting piece protruding from the outer peripheral surface of the pipe length adjusting pipe 15. One end of a link rod 17 that penetrates inside and outside of the intake silencer 6 is connected to this connecting piece 16. The end is connected to the valve body 18H of another solenoid valve 18, and by energizing the solenoid of the solenoid valve 18, the link rod 17 moves in and out, thereby moving the pipe length adjusting pipe 15 in and out of the fixed pipe 7. However, the pipe length will be changed.

The embodiment shown in FIG. 4 is another embodiment of such a pipe length adjustment pipe 15, in which the pipe length adjustment pipe 15 has two large and small extension pipes 15a.
, 15b, a small-diameter extension tube 15b is slidably fitted onto the fixed tube 7, and a large-diameter extension tube 15a is slidably fitted onto the tip of the small-diameter extension tube 15b, It is constructed so that the pipe length can be changed twice by sliding operation of both extension pipes 15a and 15b that can come in and out, and the large diameter extension pipe 1
The tip of 5a is open in a trumpet shape.

A screw shaft 19 penetrating through the intake silencer 6 and pivotally supported is screwed into the connecting pieces 16a, 16b protruding from the outer periphery of both extension pipes 15a, 15b. A screw shaft drive gear 20 is fixed to the outer end of the screw shaft drive gear 19, and this screw shaft drive gear 20 is provided outside the intake silencer 6, and is driven by a DC motor that rotates forward and backward by a certain amount of rotation according to an external signal. The extension tubes 15a and 15b are rotated by the gear 21, and the length of the main suction passage 11a is changed by moving the extension tubes 15a and 15b in and out.

Further, the screw formed on the screw shaft 19 is connected to the small diameter extension tube 15b.
The part 19b that is screwed into the connecting piece 16b is screwed into the screw pitch A.
A portion 19a shaped like this and screwed into the large diameter extension tube 15a
is formed into a screw pitch 2A that is twice as large as that, and therefore, when the screw shaft 19 is rotated, the large diameter extension tube 15 a
will move in and out twice as fast.

Most of all, this pitch ratio does not necessarily have to be twice.

Therefore, in the embodiment shown in FIG. 4, the extension tubes 15a,
The actuating device for automatically sliding operation of 15b in accordance with the engine speed will be explained based on FIGS. 5 to 7.
In FIG. 5, a rod 23 is slidably inserted through an appropriate fixed wall 22 attached to the engine, and one end of the rod 23 is in contact with a centrifugal weight 27 that rotates as the engine rotates. The balance between the centrifugal force of the centrifugal weight 27 and the spring force of the spring 24 provided between the fixed wall 22 and the tip of the rod 23 causes it to slide in and out, thereby causing one end of the rod 23 to slide inward and outward. A lever 26, which is pivotally connected to the outer end of the rod 23 and pivotally supported by a fixing pin 25, swings in the direction of the arrow AA'.

Therefore, within the swing range indicated by A-A' of the lever 26, as shown in FIG. and limit switches L2, L3, etc. are arranged corresponding to the lever 26 position at the suction path switching rotation speed position of the medium-speed rotation N2 to N5, respectively, as shown in FIGS. 6 and 8. When the lever 26 comes to the position, the lever 2
6 contacts these limit switches L1, L2, . . . to activate them.

The limit switch L1 for high-speed rotation is connected to the solenoid valve 13 that operates the switching shutter 10, and when the engine speed exceeds a certain level, the switching shutter 10 is operated to open the sub-intake passage 11b on the side of the branch pipe 8. When the speed is lower than that, the fixed pipe 7 side for medium speed is opened.

On the other hand, limit switches L2, L3 for medium speed rotation...
, the signals from the limit switches L2, L3... are applied to the DC motor! Wire it to send to M.

Then, in response to these signals, the DC motor M determines the best length H2 to match the respective rotational speeds N2 to N5.
The screw shaft 19 is set so that the main suction passage 11a is set in H5.
By driving the extension tubes 15a and 15b to move them in and out and holding them at a constant position, each rotation speed N
The intake pipe lengths H2 to H5 corresponding to the lengths H2 to N5 are obtained.

The above example shows the case of the embodiment shown in FIG. 4, but this can be similarly constructed in the embodiment shown in FIG. 2. For example, in the medium speed solenoid valve 18, the In order to set the pipe length adjustment pipe 15 at the optimum length position corresponding to the rotation speed, solenoids corresponding to each rotation speed N2 to N5 are provided around the rotation speed, and each limit shown in FIGS. 5 to 7 is set. This is achieved by energizing each solenoid with signals from switches L2, L3, . . . in accordance with the rotational speed.

Further, the operation of the switching shirt shirt 10 may be exactly the same as that of the embodiment shown in FIG.

Now, in the above structure, the volumetric efficiency ηV is shown on the joint axis, the engine speed N is shown on the horizontal axis, and each engine speed N1 to N5 is
Figure 8 shows a diagram showing the change in volumetric efficiency ηV at each intake pipe length H1 to H5 by matching each volumetric efficiency ηV to be maximum.
By using the intake pipe length H1 when the engine is at high speed, and by selecting the intake pipe lengths H2 to H5 according to each rotation speed when the engine is at medium speed, the maximum volumetric efficiency ηV at each rotation speed can be obtained. Particularly at medium speeds, high volumetric efficiency can be obtained over a wide range of N2 to N5, as shown by the dotted line H.

Note that Nc is the main suction passage 11a and the sub suction passage 1lb.
It shows the switching rotation speed.

Therefore, according to the present invention, by using the intake pipe length H during normal sailing, etc., and using the intake pipe length H2 to H5 during fishing or work using medium speed rotation N2 to N5, It is possible to obtain the maximum intake inertia effect corresponding to each high speed, and even if the medium speed range used differs depending on the type of fishing or work, the pipe length adjustment pipe allows the optimum pipe length to be determined according to each fishing method. It is possible to set high output and high torque through various fishing methods.

In particular, in the present invention, such a pipe length adjustment pipe is automatically moved according to the engine speed, so even when torque changes constantly occur during fishing or work, the intake air can be adjusted according to the change in engine speed. The pipe length can be automatically obtained, and high output and high torque can always be obtained in response to such torque changes.

In this invention, in a device that adjusts the intake pipe length in conjunction with the engine speed, the adjustment range by the pipe length adjustment pipe is limited to the medium-speed rotation range, and the shorter branch is adjusted for high-speed rotation. By opening the intake passage, we are trying to obtain the optimal intake pipe length in the high-speed rotation range, so the range of entry and exit of the pipe length adjustment pipe is limited to a small range in the medium-speed rotation range, so the space in the sliding range is reduced. It's small,
Therefore, there is an effect that the intake silencer can be constructed compactly.

Of course, in this case, the branch part of the high-speed side intake passage must be provided closer to the intake port than the manual range of this pipe length adjustment pipe, and the intake silencer will be larger accordingly than if the branch part is not provided. However, the structure can be made more compact than adjusting the length corresponding to this high-speed rotation range using only the length adjusting tube.

Furthermore, the length of the intake pipe was changed by providing an opening in the middle of the intake pipe and switching the intake passage on the inlet side and the opening side of the intake pipe as appropriate using a switching shutter. There is one described in the -14020 publication.

However, if the idea described in this publication is applied to a device equipped with a pipe length adjustment pipe as described above, the intake passage on the high speed side becomes too short, and there is a drawback that it is not necessarily possible to obtain the most suitable intake pipe length for high speed rotation. be.

That is, as mentioned above, the branch part for shaping the suction passage in two directions needs to be formed closer to the intake port than the sliding range of the pipe length adjustment pipe, and as described in the above-mentioned Utility Model Publication No. 50-14020. The same is true for the opening in the publication, but in that case, the invention described in this publication simply forms an opening on the outer periphery of the intake pipe, and in the end, the length of the intake passage on the high-speed rotation side The length is limited to the opening position of this opening, and since it must be provided closer to the intake port than the sliding range of the pipe length adjustment pipe, there is a drawback that it is generally too short.

On the other hand, in the present invention, as a branch pipe, not just an opening, the end of the intake pipe on the high-speed side protrudes beyond the other intake pipe, so there is no such drawback. By adjusting the pipe length, it is possible to easily obtain the intake pipe length that is most suitable for the high-speed rotation range.

Furthermore, if an opening is provided in the outer circumferential wall of the intake pipe as described above, the machining for the opening shape is troublesome, and furthermore, this opening part has the disadvantage of increasing suction resistance at high speeds. On the other hand, in the present invention, since it is a branch pipe, it can be easily formed into one piece by casting or the like, and it can flow smoothly from either branch pipe side, so there is no such drawback.

Furthermore, in the present invention, by arranging the suction side of the intake pipe inside the intake silencer, it is possible to reduce the noise caused by air column vibration, and especially in the case of a multi-cylinder engine, each intake pipe can be connected to one By arranging it inside the intake silencer, the structure for attaching it to the engine body becomes simple and compact.

[Brief explanation of the drawing]

Fig. 1 is a side view of a three-cylinder internal combustion engine showing an embodiment of the present invention, Figs. 2 and 4 are enlarged horizontal and vertical cross-sectional views of the tip of the intake pipe, and Fig. 3 is the installation of the switching shirt. FIGS. 5 to 7 are enlarged longitudinal cross-sectional views of the tip of the intake pipe showing the state; FIGS. FIG. 3 is a diagram showing the relationship between volumetric efficiency and engine rotation speed in the invented embodiment. 1... Intake pipe, 6... Intake silencer, 8
...Branch pipe, 10...Switching shaft,
11 a, 11 b... Suction passage, 15...
...Pipe length adjustment pipe.

Claims (1)

[Scope of utility model registration request] In an intake pipe of an internal combustion engine, one end of which is connected to an intake port of the engine, the suction side of the intake pipe is placed in an intake silencer, and the intake pipe is branched into a long length within the intake silencer. A medium-speed suction passage and a short high-speed suction passage are formed, and this branch section is equipped with a switching shutter that can selectively open and close each passage according to the rotational speed of the internal combustion engine. In addition, a length adjustment pipe is provided at the suction open end of the medium-speed suction passage, the pipe length adjusting pipe moving in and out of the pipe end in conjunction with changes in engine speed in order to change and adjust the length of the suction passage. A characteristic feature of the intake inertia pipe of an internal combustion engine.