JP3786147B2 - Engine exhaust passage switching device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
In the present invention, an engine, an exhaust pipe for a low rotation range, and an exhaust pipe for a high rotation range are connected via a switching valve, and exhaust gas from the engine is exhausted for a low rotation range or a high rotation range by this switching valve. The present invention relates to an engine exhaust passage switching device that can be switched to.
[0002]
[Prior art]
2. Description of the Related Art Conventionally, as an exhaust device that can obtain a high output by using exhaust pressure waves over a wide range of engine rotation ranges, there is one described in, for example, Japanese Utility Model Laid-Open No. 60-143125. This is provided for a low-revolution range that is provided with a switching valve for switching the flow direction of exhaust gas to one of two directions in the exhaust passage of a single-cylinder engine and one of the two outlets of this switching valve is in a low-revolution range. The exhaust pipe is connected, and the other is connected to an exhaust pipe for a high rotation range suitable for a high rotation range.
[0003]
In this switching valve, an exhaust passage formed by bifurcating two branch passages having a common inlet is formed in the valve body, and a rotating body having a curved communication passage is formed at a central axis at a branch portion of the exhaust passage. It is fitted so that it can rotate freely. The low exhaust region exhaust pipe is connected to the one exhaust passage, and the high rotational region exhaust pipe is connected to the other exhaust passage.
[0004]
Then, by rotating the rotating body about the central axis, the curved communication passage is moved to select one exhaust passage.
[0005]
[Problems to be solved by the invention]
However, in such a conventional system, the temperature of the exhaust pipe after switching may be significantly different from the temperature of the exhaust pipe before switching, and the output is temporarily sufficient until the temperature reaches a predetermined temperature. There may be a time zone that cannot be taken out.
[0006]
Accordingly, an object of the present invention is to provide an engine exhaust passage switching device that can prevent a temporary decrease in output during switching.
[0007]
[Means for Solving the Problems]
In order to achieve this object, the invention according to claim 1 is configured such that an engine and an exhaust pipe for a low rotation range and an exhaust pipe for a high rotation range are connected via a switching valve, and the switching valve is connected to the engine. When the acceleration is greater than a predetermined value, the exhaust pipe temperature at the switching destination is detected when the exhaust gas is switched to the low speed range or high speed range exhaust pipe. The engine exhaust passage switching device is provided with a control device for setting the ignition timing or the exhaust timing.
[0008]
According to a second aspect of the present invention, an engine, an exhaust pipe for a low engine speed range, and an exhaust pipe for a high engine speed range are connected via a switching valve, and exhaust gas from the engine is used for a low engine speed range by the switching valve. In the exhaust passage switching device that can be switched to the exhaust pipe for the high rotation region, when the acceleration is larger than a predetermined value, the temperature of the exhaust pipe at the switching destination is detected, and at the ignition timing or the exhaust timing according to the temperature, The engine exhaust passage switching device is provided with a control device that is preset in advance of switching of the switching valve.
[0009]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be described below.
[0010]
1 to 6 show an embodiment of the present invention.
[0011]
First, the configuration will be described. Reference numeral 1 in FIGS. 1 and 2 denotes a water-cooled two-cycle single-cylinder engine of a motorcycle. The single-cylinder engine 1 includes a cylinder body 2 and a cylinder head 3 fixed to the cylinder body 2. A connecting rod 5 having a lower end connected to the crankshaft 4 is disposed, a piston 6 is attached to the upper end of the connecting rod 5, and a spark plug 30 is disposed on the cylinder head 3.
[0012]
The single-cylinder engine 1 is connected via a switching valve 8 to a low-revolution range exhaust pipe 9 suitable for a low revolution range and a high-revolution range exhaust pipe 10 suitable for a high revolution range. Yes.
[0013]
Specifically, the switching valve 8 has a valve main body 12 fixed to the cylinder body 2 and a rotating body 13 rotatably disposed on the valve main body 12.
[0014]
The valve body 12 has a bifurcated exhaust passage 12d formed by communicating two outlets 12b and 12c with one inlet 12a, and the inlet 12a is connected to an exhaust port 2a formed in the cylinder body 2. As shown, the bolt 14 fixes the cylinder body 2. Further, the exhaust pipes 9 and 10 are fixed to the valve body 12 with bolts (not shown), and the low-rotation region exhaust pipe 9 is connected to one outlet 12b of the valve body 12 and the other outlet 12c. The exhaust pipe 10 for high rotation regions is connected to each other (see FIG. 3).
[0015]
As shown in FIGS. 2 and 3, the rotating body 13 has a cylindrical shape with a curved communication path 13a and is fitted to a branch portion of the valve body 12 so as to be rotatable about the central axis O. Has been. The inlet 13b of the communication passage 13a is connected to the exhaust port 2a of the cylinder body 2, and the outlet 13c of the communication passage 13a is connected to both outlets 12b and 12c of the valve body 12 by rotating the rotating body 13. Connected.
[0016]
Further, in the exhaust passage 12d of the valve body 12, the axis P direction of the branch passages 12e and 12f having both outlets 12b and 12c is lower than the central axis O of the rotating body 13 by an angle θ as shown in FIG. Inclined. As shown in FIG. 4, both outlets 12b and 12c of both branch passages 12e of the valve body 12 are located below the central axis O of the rotating body 13, and the two outlets 12b and 12c An angle α formed by a line connecting the centers of 12b and 12c and the central axis O is smaller than 180 °, and is set to 120 ° here.
[0017]
The rotating body 13 is set so as to be rotationally driven by the driving device 17. Specifically, as shown in FIG. 3, the driving device 17 has a rotating shaft 18 protruding from the rotating body 13, and a first gear 19 having a small diameter is fixed to the rotating shaft 18 as shown in FIG. The first gear 19 is meshed with a second gear 20 having a large diameter. The second gear 20 is rotated by a motor 21 as shown in FIG. 1, whereby the rotating body 13 is rotated about the central axis O. The driving device 17 is connected to the control device 23.
[0018]
Further, as shown in FIG. 2, a displacement member 25 is disposed on the upper side of the exhaust port 2a of the cylinder body 2 to displace the upper edge of the exhaust port 2a up and down. The displacement member 25 is disposed so as to be rotatable about a shaft 25a, and is displaced by the motor 26 shown in FIG. 1, thereby displacing the position of the upper edge of the exhaust port 2a. The motor 26 is connected to the control device 23 to be driven and controlled.
[0019]
As shown in FIG. 1, the control device 23 is connected to a rotation speed sensor 27 provided in the portion where the crankshaft 4 is disposed, and the rotation speed sensor 27 detects the rotation speed of the single cylinder engine 1. A signal from the rotational speed sensor 27 is input, and temperature sensors 28 and 29 for detecting the temperatures of the exhaust pipes 9 and 10 are connected, and signals from the temperature sensors 28 and 29 are input. ing. The control device 23 to which signals from the sensors 27, 28, 29 are input controls the ignition timing by the spark plug 30, the switching timing by the switching valve 8, and the exhaust timing by the displacement member 25. Yes.
[0020]
That is, the control device 23 sets the switching timing (switching engine speed) of both the exhaust pipes 9 and 10 by detecting the temperature of both the exhaust pipes 9 and 10, and also by the signal from the rotational speed sensor 27, When the switching engine speed is reached, the motor 21 of the switching valve 8 is driven and controlled so that the exhaust pipes 9 and 10 are switched.
[0021]
Moreover, when the acceleration is larger than a predetermined value, the temperature of the switching exhaust pipe 9 or 10 is detected by the temperature sensors 28 and 29, and the switching valve 8 is switched at the ignition timing and the exhaust timing based on the temperature. Is controlled in advance (details will be described in the following section of action).
[0022]
Next, the operation of the exhaust passage switching device having such a configuration will be described.
[0023]
The rotational speed of the single cylinder engine 1 is detected by the rotational speed sensor 27, and a signal from the rotational speed sensor 27 is input to the control device 23. When the rotational speed at this time is smaller than a predetermined value, the switching valve 8 The rotating body 13 is set at the position shown by the solid line in FIG. 3, and the exhaust gas passes through the communication passage 13a of the rotating body 13 via the exhaust port 2a of the cylinder body 2 and is used for the low rotation region from the outlet 12b of the valve body 12. It flows into the exhaust pipe 9 and is exhausted.
[0024]
When the engine speed becomes larger than a predetermined value, the control device 23 drives the motor 21 so that the rotating body 13 is centered on the central axis O via the first and second gears 19 and 20. 4 is rotated clockwise by 120 °, switched to the exhaust pipe 10 for high rotation range, and exhausted.
[0025]
In this case, switching can be performed by rotating the rotating body 13 by 120 ° in the direction of the arrow in FIG. 4, so that the switching time can be shortened compared to the conventional 180 ° rotation, and switching can be performed. A temporary decrease in output at the time can be suppressed as compared with the conventional case, and drivability can be improved.
[0026]
Further, the engine speed at the time of switching is set as follows. That is, FIG. 5 shows the relationship between the engine speed and the output when the low-revolution range exhaust pipe 9 or the high-revolution range exhaust pipe 10 is used, and the characteristic curve A1 is shown at a certain temperature. The characteristic curve B1 is obtained when the low-rotation region exhaust pipe 10 is used at a certain temperature. In this case, it is preferable that the engine speed when switching both the exhaust pipes 9 and 10 is set near the intersection P where the two characteristic curves A1 and B1 intersect with each other because the output fluctuation is small.
[0027]
However, when the temperature of the exhaust pipes 9 and 10 changes, when the exhaust pipe 9 for the low rotation range is used, the characteristic curve changes to the characteristic curve A2 or A3, and the exhaust pipe 10 for the high rotation range is used. If it is, it changes like a characteristic curve B2 or B3. Therefore, since the position of the intersection P also changes due to the change of the characteristic curves A1... Due to the temperature change of both the exhaust pipes 9 and 10, it is necessary to change the engine speed at the switching point according to this change.
[0028]
Therefore, first, the characteristic curves A and the like at the respective temperatures of the exhaust pipes 9 and 10 are obtained in advance through experiments or the like, and these are input to the control device 23 as data. Then, the temperatures of both the exhaust pipes 9 and 10 are detected by the temperature sensors 28 and 29, and characteristic curves A1... B1. Thereafter, the optimum engine speed for switching the exhaust pipes 9 and 10 is obtained by obtaining the engine speed at the intersection between the selected low-rotation region characteristic curve A1 and high-rotation region characteristic curve B1. A value of the engine speed is calculated.
[0029]
When this value is reached, the drive device 17 is controlled by a signal from the control device 23 to switch both the exhaust pipes 9 and 10 as described above.
[0030]
In this way, the fluctuation of the output at the time of switching between the exhaust pipes 9 and 10 is reduced, and smooth switching can be performed.
[0031]
On the other hand, when the temperature of the exhaust pipe 9 or 10 being used is detected by the temperature sensors 28 and 29 and this signal is input to the control device 23, the spark plug 30 and the displacement member are generated by the signal from the control device 23. 25 is operated, and the ignition timing and the exhaust timing of the spark plug 30 are controlled based on the temperature.
[0032]
In addition, when the acceleration is larger than the predetermined value, the temperature sensor 28 or 29 is used to set the temperature of the switching destination exhaust pipe 9 or 10 before the predetermined time (X / 10 seconds) to reach the switching engine speed obtained above. The ignition timing and the exhaust timing of the spark plug 30 based on the detected temperature are controlled in advance in advance of the switching of the switching valve 8. Such control is performed in the same way during both acceleration and deceleration.
[0033]
As described above, when the acceleration is larger than a predetermined value, the temperature of the switching destination exhaust pipe 9 or 10 is detected before switching between the two exhaust pipes 9 and 10, and the switching valve 8 is switched in advance in advance. By controlling the ignition timing and the exhaust timing corresponding to the temperature, the time lag can be suppressed to a minimum, and a temporary decrease in output at the time of switching the exhaust pipe can be prevented.
[0034]
Accordingly, it is desirable that the predetermined time (X / 10 seconds) is set to be the ignition timing and the exhaust timing based on the temperature of the exhaust pipe 9 or 10 after the switching at the time when the switching is completed. Further, as shown in FIG. 6, the acceleration is obtained within a certain period of time until the inclination (θ) is obtained from the relationship between the time and the engine speed, or until the next detected speed is reached from a certain engine speed. It is detected by determining whether or not there is.
[0035]
In the above embodiment, when the acceleration at the time of switching is larger than a predetermined value, the ignition timing or the exhaust timing is controlled in advance in advance of the switching of the switching valve. Even when the acceleration at the time of switching is not so large, the temperature of the exhaust pipe at the switching destination can be detected and set to the ignition timing or the exhaust timing according to this temperature. Even in such a case, it is possible to prevent a temporary decrease in output during switching.
[0036]
Further, in the above embodiment, the ignition timing and the exhaust timing are controlled, but it goes without saying that either the ignition timing or the exhaust timing may be controlled.
[0037]
【The invention's effect】
As described above, according to the first aspect of the present invention, before switching between the two exhaust pipes, the temperature of the switching destination exhaust pipe is detected, and the ignition timing or the exhaust timing is set according to this temperature. Thus, it is possible to prevent a temporary decrease in output at the time of switching.
[0038]
According to the second aspect of the present invention, when the acceleration is larger than a predetermined value, the temperature of the switching exhaust pipe is detected before switching between the two exhaust pipes, and the ignition timing or the exhaust timing is determined according to this temperature. The time lag can be suppressed to a minimum by setting in advance prior to the switching of the switching valve, and a temporary decrease in output at the time of switching can be prevented. .
[Brief description of the drawings]
FIG. 1 is a front view showing an engine and an exhaust pipe according to an embodiment of the present invention.
FIG. 2 is a cross-sectional view along the vertical direction of the engine or the like according to the embodiment.
3 is a cross-sectional view taken along line AA of FIG. 2 according to the same embodiment.
4 is a diagram of FIG. 2 according to the same embodiment viewed from the direction of arrow B. FIG.
FIG. 5 is a graph showing the relationship between engine speed and output according to the embodiment.
FIG. 6 is a graph showing the relationship between engine speed and time according to the embodiment.
[Explanation of symbols]
1 Single cylinder engine
2a Exhaust port 8 Switching valve 9 Low speed exhaust pipe
10 Exhaust pipe for high speed range
12 Valve body
12a entrance
12b, 12c exit
12d exhaust passage
12e, 12f Branch passage
13 Rotating body
13a Communication passage
13b entrance
13c exit
17 Drive unit
23 Control unit

Claims (2)

The engine is connected to an exhaust pipe for a low speed range and an exhaust pipe for a high speed range via a switching valve, and the exhaust from the engine can be switched to an exhaust pipe for a low speed range or a high speed range with the switch valve. In the exhaust passage switching device,
An exhaust passage switching device for an engine, comprising a control device for detecting a temperature of an exhaust pipe as a switching destination and setting an ignition timing or an exhaust timing according to the temperature. The engine is connected to an exhaust pipe for a low speed range and an exhaust pipe for a high speed range via a switching valve, and the exhaust from the engine can be switched to an exhaust pipe for a low speed range or a high speed range with the switch valve In the exhaust passage switching device,
A control device is provided that detects the temperature of the exhaust pipe at the switching destination when the acceleration is greater than a predetermined value, and presets the ignition timing or exhaust timing according to the temperature prior to the switching of the switching valve. An exhaust passage switching device for an engine.

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