JPS63277815A - Mirror cycle engine - Google Patents

Abstract

PURPOSE:To attempt improvement of sealing ability when a suction passage is closed by providing the way of the suction passage with a mushroom shaped mirror valve opening/closing the suction passage. CONSTITUTION:A suction valve 6 and an exhaust valve 7 are provided to the opening of a suction passage 4 and an exhaust passage 5 both of which are connected to a cylinder 1 respectively. A mushroom shaped mirror valve 15 opening/closing the suction passage is provided on the way to the suction passage 4 so as to allow the mirror valve 15 to close the suction passage 4 before the closing of the suction valve 6. This constitution thereby enables the suction passage to be sealed sufficiently with smaller driving force for improving sealing ability when the suction passage is closed.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a Miller cycle engine that improves engine thermal efficiency by lowering the substantial compression ratio by cutting off the flow of intake air during the intake stroke. Can be used in motorcycles, four-wheeled vehicles, and other internal combustion engines.

[Conventional technology]

Conventionally, a Miller cycle engine that can obtain a low compression ratio and a high expansion ratio has been proposed as a means of improving engine thermal efficiency (4th Internal Combustion Engine Symposium Proceedings P13
9 to P143, and Proceedings of the 6th Joint Symposium on Internal Combustion Engines, P2O1 to P2O6), this Miller cycle engine has a substantial This lowers the compression ratio. A rotary valve is placed in the intake passage as a means for blocking the flow of intake air, and this rotary valve is provided with an intake inlet and an intake outlet to allow the intake passage to communicate with each other. There is a structure in which the intake passage is blocked by a side wall between the inlet and the intake outlet. In this case, in order to sufficiently block the intake passage with the rotary pulp, a roughly semi-cylindrical slide plate is attached to the circumferential surface of the rotary valve, and the slide plate is brought into close contact with the opening of the intake passage by its centrifugal force. It has been proposed (Utility Model Application Publication No. 62-739).

[Problem that the invention seeks to solve]

By the way, it is important to sufficiently close or seal the opening of the intake passage, and to reduce the sliding resistance during rotation of the rotary valve to allow the rotary valve to operate smoothly, reduce driving force, and reduce wear. Since these are originally contradictory, there is a problem in that although the above structure can provide a sufficient seal, it cannot necessarily reduce the sliding resistance sufficiently.

SUMMARY OF THE INVENTION An object of the present invention is to provide a Miller cycle engine having a valve of a new configuration that can achieve sufficient sealing with less driving force when blocking an intake passage.

[Means for solving problems]

The present invention provides an engine in which a mushroom-shaped intake valve and an exhaust valve are provided at the openings of an intake passage and an exhaust passage communicating with the inside of the cylinder into the cylinder. This mirror cycle engine is provided with a mirror valve and a valve drive mechanism that causes the mirror valve to close the intake passage prior to the intake passage being closed by the intake valve.

[Effect]

The mirror cycle operation in such a configuration is performed by closing the mirror valve for intake timing control during the air-fuel mixture intake operation performed when the intake valve is opened. Unlike a rotary valve, this mirror valve has a mushroom (poppet valve) shape, so its operating resistance is extremely low and the seal is sufficient.

〔Example〕

Embodiments of the present invention will be described below based on the drawings. Here, the same or equivalent components in each embodiment are denoted by the same reference numerals, and the description thereof will be omitted or simplified.

A first embodiment of the invention is shown in FIGS. 1-4.

In the overall schematic diagram of FIG.
and the exhaust passage 5 is opened. The opening 4A of the intake passage 4 is provided with a mushroom-shaped intake valve 6, and the opening 5A of the exhaust passage 5 is provided with a mushroom-shaped exhaust valve 7, and the openings 4A and 5A are opened and closed. It is made possible. Separate cams 8.9 are brought into contact with the stem tips 6A and 7A of both the intake and exhaust bubbles 6.7, and these cams 8 and 9 are rotated by receiving power from a crankshaft (not shown). The camshafts 10 and 11 are provided integrally with each other. In addition, the tip 6 of the stem portion of the intake valve 6 and the exhaust valve 7
Compression coil springs 12 and 13 similar to those in a normal engine are interposed between the vicinity of A and 7A and the cylinder head 3, and the mushroom-shaped heads of both pulps 6 and 7 are compressed by the urging force of these springs 12 and 13. 6B and 7B normally close the openings 4A and 5A, and the stem ends 6A and 7A are brought into contact with the cam 8.9 as described above.

In the middle of the intake passage 4 and upstream of the position where the intake valve 6 is provided, there is a mushroom-shaped mirror valve 15 for controlling the intake timing which allows the intake passage 4 to be shut off and communicated. are placed in parallel. A cam 16 for mirror cycle operation is in contact with the stem end 15A of the mirror valve 15, and the stem end 15A is in contact with the cam 16 for mirror cycle operation.
A compression coil spring 17 is interposed between the vicinity of 5A and the cylinder head 3, and the biasing force of this spring 17 causes the valve 1 to
The mushroom-shaped head 15B of No. 5 normally closes the midway opening 4B of the intake passage 4, and the stem end 15A abuts against the cam 16.

The cam 16 for mirror cycle operation is connected to the camshaft 1.
As shown in FIG. 2, this camshaft 18 is connected to the intake valve driving camshaft 10 via a phase shift device 20. At this time, the phase shift device 20 and the drive system of the camshaft 10 constitute a valve drive mechanism for the mirror valve 15.

The phase change device 20 has first and second large gears 21° 22 of the same shape fixed to both the camshafts 10.18 on the intake valve side and the mirror valve side, respectively, and is interposed and meshed with the large gear 2.
1.22, two first and second intermediate gears 23 and 24 of the same shape and a first large gear 21.
and the first intermediate wheel gear 23, and allows the first intermediate wheel gear 23 to revolve and rotate with respect to the first large gear 21; A second link 26 rotatably supports the second intermediate gear 23, 24 and connects the two-handed gears 23, 24, and connects the second intermediate gear 24 and the second large gear 22. and a third bell crank-shaped third intermediate wheel gear 24ψ which allows revolution and rotation with respect to the second large gear 22 and has an operating portion 27A extending from the connecting portion side with the second intermediate wheel gear 24. A tension spring 28 that is stretched between the link 27, the operating part 27A of the third link 27, and an engine fixing part such as the cylinder head 3, and always biases the third link 27 in the counterclockwise direction in the figure. , a first stopper 29 that restricts the counterclockwise rotation of the third link 27 by the tension spring 28, and an operating portion 27A of the third link 27.
one end is connected to the spring 28, and the third
The operating wire 3 rotates the link 27 clockwise in the figure.
0, a second stopper 31 that restricts clockwise rotation of the third link 27 by the operating wire 30, and a throttle grip 3 to which the other end of the operating wire 30 is connected.
It is composed of 2.

When the throttle grip 32 is thereby rotated, the third link 27 is displaced to the two-dot chain line position via the operating wire 30, and the first and second intermediate gears 23.
24 are similarly displaced to the two-dot chain line position while maintaining meshing with each other and with the first and second large gears 21.22, and the twelfth and second intermediate gears 23.24 Due to the rotation and revolution of each of the small gears 23 and 24 accompanying the displacement, the phase of meshing of the second large gear 22 with respect to the first large gear 21 changes. At this time, the state before the third link 27 is not displaced, that is, the state before the throttle grip 32 is not rotated (reference position)
corresponds to the low speed range of the engine, and the throttle grip 32
The rotated state corresponds to the high speed range of the engine.

Further, as the throttle grip 32 rotates, the second large gear 22 is rotated in the opposite direction (see the broken line arrow) to the rotational direction (see the solid line arrow) of the first large gear 21 when it is driven. The second large gear 22 is retarded by a predetermined angle with respect to the reference position, so that the opening/closing timing of the mirror valve 15 almost coincides with the opening/closing timing of the intake valve 6, and sufficient intake air commensurate with high speed rotation can be performed. It has become so.

An intake pipe length variable device 40 is connected to the intake passage 4 of the cylinder head 3 . This intake pipe length variable device 40
is a proximal intake pipe 41 fixed to the cylinder rod 3;
A fixed intake pipe 4 flange-connected to this proximal intake pipe 41
2, a movable intake pipe 43 inserted movably in the axial direction into the fixed intake pipe 42, a rack 44 fixed to the outer periphery of the movable intake pipe 43, and a fixed intake pipe meshed with the rack 44. 43, a servo motor 46 for rotationally driving the pinion 45, a control means 47 for outputting a drive signal to the servo motor 46, and a control means 47 for controlling the servo motor drive. and an engine rotation speed detection means 48 which inputs an engine rotation speed signal, and this detection means 48 includes:
It is comprised of appropriate means such as a sensor that detects the number of revolutions of the crankshaft (not shown) and an ignition pulse sensor that detects the number of times the ignition plug is fired. Thereby, when the servo motor 46 is driven according to the engine speed, the movable intake pipe 43 moves back and forth in the left-right direction via the pinion 45 and the rack 44, so that the length of the intake pipe changes.

At this time, in order to increase the intake inertia when the engine is running at a low speed, the pinion 45 is rotated counterclockwise in the figure, and the movable intake pipe 43 is advanced to the right, increasing the length of the intake pipe. On the other hand, when the engine is running at a high speed, the pinion 45 is rotated clockwise to reduce intake resistance, and the movable intake pipe 43 is moved back to the left to shorten the length of the intake pipe. ing.

An exhaust pipe length variable device 60 is connected to the exhaust passage 5 of the cylinder head 3. This exhaust pipe length variable device 60
For example, a proximal exhaust pipe 61 fixed to the cylinder rod 3,
A fixed exhaust pipe 62 is fixed to the proximal exhaust pipe 61 and constitutes a muffler outer pipe, and a plurality of stays 63 are housed in the fixed exhaust pipe 62 and are attached to the fixed exhaust pipe 62.
A movable exhaust pipe 65 that constitutes a muffler inner pipe is supported so as to be slidable in the axial direction on the guide vibro 4 fixed via the guide vibro 4, a tapered valve body 65A formed at one end of this movable exhaust pipe 65, and a fixed A valve 66 consisting of a valve seat portion 62A formed on the inner surface of the enlarged diameter portion of the exhaust pipe 62; a sliding plate 68 rotatably supported by the fixed exhaust pipe 62 via a support shaft 67;
This sliding Fi 68 is fixed at an eccentric position (see FIG. 3) and is engaged with a long groove 65B formed on the side surface of one end of the movable exhaust pipe 65, causing the movable exhaust pipe 65 to move as the rocking plate 68 swings. An eccentric pin 69 that opens and closes the valve 66 by moving forward and backward a predetermined amount in the axial direction, a lever 70 fixed to the outer end of the support shaft 67, and a support interposed between the fixed exhaust pipe 62 and the support shaft 67. An eccentric pin 69 biases the shaft 67 clockwise when viewed from below in FIG. 1 and is fixed to the support shaft 67 via a swing plate 68.
The movable exhaust pipe 65 is always biased to the right position shown by the solid line in the figure.
a torsion coil spring 71 that presses the valve body portion 65A against the valve seat portion 62A of the fixed exhaust pipe 62 to normally close the valve 66; An operating cable 74 that is guided by a cable guide 72 provided on the vehicle body fixing part and whose other end is fixed to a cable winding pulley 73 and a cable winding pulley 7
3 and a servo motor 75 which is controlled by a signal from a control means 47 which is actuated by a signal from the engine rotation speed detection means 48.

As a result, the servo motor 75
When driven, the support shaft 67 is rotated counterclockwise via the pulley 73, operating cable 74, and lever 70 against the screw recoil spring 71, and the rotation of the support shaft 67 causes the sliding plate 68 to rotate. The eccentric pin 69 is positioned to the left as shown by the chain line in the figure, and the movable exhaust pipe 65 is also moved to the left to close the valve 6.
6 is released. When the valve 66 is opened or closed, engine exhaust gas is discharged through the outside or inside of the movable exhaust pipe 65, so that the actual length of the exhaust pipe changes. At this time, the valve 66 is closed when the engine is rotating at a low speed to increase exhaust inertia, while the operating wire 74 is closed by the servo motor 75 when the engine is rotating at a high speed to reduce exhaust resistance. The valve 66 is opened by being pulled against the spring 71.

Note that the engine speed when the variable intake pipe length device 40 is activated and the engine speed when the variable exhaust pipe length device 60 is activated do not necessarily have to be the same, and may be determined as appropriate for implementation. .

Next, the operation of this embodiment will be explained with reference to MrgJ (PV diagram) showing the relationship between cylinder pressure and cylinder volume in FIG. 4.

When the engine is started, the crankshaft (not shown) is driven to move the piston 2 up and down, and the camshaft 10.11 is also driven, and the intake valve 6 and the exhaust valve 7 are moved to a predetermined position by the action of the cams 8 and 9. The valve is opened and closed at the appropriate timing to intake the air-fuel mixture and exhaust the combustion gas, and at the same time, a spark is ignited from an ignition plug (not shown) to continue operating the engine. During this operation, when the engine is in a low speed rotation range, the mirror valve 15 is opened at the same time or prior to the opening operation of the intake valve 6, and the air-fuel mixture is sucked into the cylinder 1 at the same time as the intake valve 6 is opened. In addition, the mirror valve 15 is closed prior to the closing operation of the intake valve 6, and further intake of the air-fuel mixture into the cylinder l is prevented, resulting in a substantially low compression ratio and a maximum The average effective thickness ('Psi) in the figure can be increased without increasing the combustion pressure (Pmax).

In addition, due to the mirror valve 15 being blocked, the mirror valve l5
Negative pressure is forcibly created in the intake passage 4 on the downstream side of the engine, and a supercharging effect occurs due to the inertia effect of the intake air, thereby improving the volumetric efficiency particularly in the low and medium speed ranges. Therefore, thermal efficiency in the compression stroke is improved.

Furthermore, the timing at which the mirror valve 15 shuts off intake air during the intake stroke is changed by the phase shift device 20 depending on the operating state of the engine. That is, when the throttle grip 32 is turned to achieve an acceleration state, the third link 27 is displaced from the solid line position to the chain line position via the operating wire 30 against the spring 28. Accordingly, the second intermediate small gear 24 rotates while revolving around the second large gear 22, and the first intermediate small gear 23 connects to the first large gear 21 via the second link 26. The second large gear 2 rotates while revolving around the first large gear 21.
2 is retarded by a predetermined angle, and the intake start and closing timings of the mirror pulp 15 are also delayed relative to the intake start and closing timings of the intake valve 6, so that the intake air into the cylinder 1 is shut off later, and the intake valve 6 is delayed by a predetermined angle. Sufficient air-fuel mixture is supplied almost at the same time as the opening/closing timing, resulting in an intake operation suitable for the high-speed range.

The improvement of thermal efficiency by the so-called Miller cycle, which shuts off the intake air in the middle of the intake stroke, is shown in Figure 4.
This will be explained using a -V diagram.

In FIG. 4, the cycle A-F shown by the solid line is the normal P
−■It is a characteristic. In other words, intake begins at point A, completes at point B, then adiabatic compression occurs along the solid line toward point C in the upper left, and isobaric combustion occurs from point C to point C. After isobaric combustion is carried out from to point E, adiabatic expansion is carried out along the solid line toward point F at the lower right, then point B is reached, and exhaust is completed. At this time, the area surrounded by points B, C, D, E, F, and B becomes the work of the engine.

In addition, as mentioned above, the mirror pulp 15 during the intake stroke
When the closing operation is illustrated in FIG. 4, it is shown by a dashed line in the figure. That is, when intake air is cut off at point B1 in the middle of the intake stroke starting from point A, compression is performed along the dashed line toward point CI, and the diagonally shaded area from the upper right to the lower left in the figure , that is, points B,,C
,,C.

B, B, ′? ! The amount of work will increase by the area surrounded.

By the way, while the engine is running, when the engine speed is low, the engine speed detecting means 4 detects the engine speed as described above.
In response to the signal from 8, the control means 47 causes the variable intake pipe length device 40 and the variable exhaust pipe length device 60 to be set to a long state in order to increase intake inertia and exhaust inertia. The movable intake pipe 43 is advanced to the right, and the valve 66 of the variable exhaust pipe length device 60 is closed so that exhaust gas is discharged through the movable exhaust pipe 65. These increases in intake inertia and exhaust inertia supercharge the air-fuel mixture and improve output characteristics in the low and medium speed ranges.

On the other hand, when the engine rotation speed detection means 48 detects that the engine rotation speed is a high rotation speed, the control means 4
The servo motors 46 and 75 of the variable intake pipe length device 40 and variable exhaust pipe length device 60 are driven by the signal from 7, and the movable intake pipe 43 is moved to the left to shorten the length of the intake pipe, and the movable exhaust pipe 65 is also moved. Moved to the left and valve 6
6 is opened, and the exhaust gas is directly discharged from the opened portion of the valve 66 to the fixed exhaust pipe 62, thereby substantially shortening the length of the exhaust pipe. This reduces the intake resistance in the high speed range and improves the output characteristics in the high speed range.

Next, the supercharging operation associated with an increase in intake and exhaust pipe length in the low and medium speed range will be explained based on Fig. 4, in comparison with the supercharging operation by a so-called supercharger that uses engine rotation for supercharging. .

In Fig. 4, the characteristics during supercharging are as shown by the broken line, inhalation starts from point A, points B, B*
, Cm, D! , El, Ft, Bt, B, A. Draw a cycle of points B, Ct, Dz, Sn,, Fyo, Bt.
The area surrounded by is the amount of work. When using this supercharger, there is not only a power loss due to driving the supercharger (but also because the intake boost is changed, the combination of this supercharger and the Miller cycle mentioned above does not necessarily have the characteristics of both). cannot be made to work.

On the other hand, when supercharging the Miller cycle by increasing the length of the intake and exhaust pipes as in this embodiment, there is no such problem. That is, in FIG. 4, the maximum combustion pressure (Pn
+ax) changes from point D1 in the mirror cycle to , and accordingly, point E3 . F3. Draw the process of B. Therefore, in the combination of the Miller cycle and the variable intake/exhaust pipe length system of this embodiment, the intake boost during intake is not changed, so the Miller cycle can work effectively, and supercharging can also be performed. The amount of work is points BI and C.
This is the area surrounded by I, Ds, Es, Fs, B, B+, and in addition to the increase in work due to the mirror cycle mentioned above, the area shaded from the upper left to the lower right, that is, the point Dr '+ Ds, E3,F,,F,,E',,
The amount of work in the range D is further increased.

As described above, this embodiment has the following effects.

That is, the mushroom-shaped mirror valve 15 is used as an intake flow blocking means in the middle of the intake stroke in the mirror cycle.
Since the valve is used, the valve structure can be simplified and the driving power can be extremely reduced. In addition, since the mirror valve 15 has a mushroom shape, it is possible to ensure sealing when the valve is closed, and the valve structure technology that has been widely used in intake and exhaust valves can be applied as is, reducing development costs. . Furthermore, the intake valve 6 and the mirror valve 15
Since it is provided substantially parallel to the valve insertion hole, manufacturing such as forming the valve insertion hole becomes easy, and costs can be reduced. Also,
In addition to the characteristic improvement by the Miller cycle, the characteristics can be further improved by the supercharging effect by the variable intake pipe length device 40 and the variable exhaust pipe length device 60, and high output can be obtained over the entire range from low speed range to high speed range. At this time, the mirror cycle and variable intake and exhaust pipe lengths do not interfere with each other's characteristics, and compared to combinations with superchargers etc.
Sufficient characteristic improvements can be made.

In implementing the first embodiment, the camshaft lO of the intake valve 6 and the camshaft 1 of the mirror valve 15 are
The phase changing device 20 that operates in conjunction with Not limited to the operation of the grip 32,
It may be operated by a servo motor or the like that is operated according to the engine speed, or it may be operated manually. Furthermore, the movable intake pipe 43 and the movable exhaust pipe 65 in the variable intake pipe length device 40 and the variable exhaust pipe length device 1f60 are driven as follows.
The system is not limited to the servo motors 46 and 75, and may be manually operated. Even if a drive source is used, a fluid pressure cylinder, a solenoid, or other drive source may be used. The exhaust pipe 65 is provided inside the fixed exhaust pipe 62 and the length of the exhaust pipe can be changed by opening and closing the valve 66. A structure in which the exhaust pipe length is simply changed by sliding may also be used.In this case, it goes without saying that the exhaust pipe length may be increased in the low to medium speed range. Furthermore, intake and exhaust pipe length variable device 40.60
The operation control is not limited to the one performed according to the engine speed as in the present embodiment, but may be performed according to the throttle opening degree and other engine operating conditions.

FIG. 5 shows a second embodiment of the present invention, in which the opening and closing operations of the intake valve and the mirror valve are performed by a single camshaft, and the phase change is performed by the rocker arm of the mirror bubble. This is how it is done.

That is, at the tips 6A and 7A of the stem portions of the intake pulp 6 and the exhaust pulp 7, rocker arms 81.8 each have one end supported by the rad 3 to the cylinder so that the position thereof can be adjusted.
The other ends of the two rocker arms 81, 82 are brought into contact with each other.
Cams 8 and 9 fixed to camshafts 10 and 11, respectively, are in contact with the middle of the cams. A mirror pulp cam 16 is fixed to the intake valve side camshaft 10 at a predetermined angular phase shift with respect to the cam 8, and this cam 16 has one end of a rocker arm 86 that is swingably supported on a shaft 85. is in contact with this rocker arm 8
The other end of the mirror pulp 6 is in contact with the stem end 15A of the mirror pulp 15. At this time, the shaft 85 is fixed to the cylinder head 3.

A phase conversion device 90 is provided at the shaft 85 of the rocker arm 86 . This phase shifter 90 is integrally formed with an eccentric disk 9I that is rotatably supported by a shaft 85 and is eccentric to the shaft 85 and engaged in a recess 86A provided in a rocker arm 86. and a pinion 92 concentric with the shaft 85;
A rack 93 meshed with the pinion 92 and slidable on the cylinder rod 3; an operating wire 9'4 connected at one end to the rack 93 and connected at the other end to the throttle grip 32; It is composed of a compression coil spring 95 that biases the rack 93 to the left in the figure, and a stopper 96 that restricts the movement of the rack 93 due to the spring 95.

In such a configuration, when the throttle grip 32 is rotated to the high speed side, the rack 9 is connected via the wire 94.
3 is moved to the right in the figure against the spring 95, and the pinion 9
2, the eccentric disk 91 is rotated, and the rocker arm 86 is moved to the upper left in the figure. Therefore, the rocker arm 8 is relative to the camshaft 10 which is being rotated counterclockwise as shown by the arrow in the figure, and in turn, the mirror cycle cam 16.
6 is retarded by a predetermined angle, and the opening/closing timing of the mirror valve 15 is also delayed to substantially match the opening/closing timing of the intake pulp 6,
Sufficient intake is performed in the high speed range. The operations other than the operation of this phase conversion device 90 are the same as those in the previous embodiment.

In addition to achieving the same effects as in the first embodiment, this embodiment also has the advantage of reducing the number of camshafts 2 by one, making the engine more compact, and reducing manufacturing costs. Can be added.

In this second embodiment, the intake pulp cam 8 and the mirror valve cam 16 are provided separately, but the rocker arms 81 and 86 are arranged appropriately, that is, the abutting positions with the cams are set close to each other. By providing a single cam, it is also possible to operate with one cam. Further, in this embodiment, a locking mechanism may be provided at each position of phase conversion of the eccentric disk 91.

A third embodiment of the present invention is shown in FIG. 6, and this embodiment is a modification of the phase shift device 90 in the second embodiment, and is an example of a structure in which the fulcrum position of the rocker arm itself is moved.

That is, the phase conversion device 100 in this embodiment includes a rocker arm 101 whose one end is brought into contact with the mirror valve cam 16 and whose other end is brought into contact with the stem end 15A of the mirror valve 15.
A shaft 102 protruding from the center of the shaft 102 is swingably supported by a sliding bearing 103. This sliding bearing 103 is connected to the elongated hole 104 of the bracket 104 fixed to the cylinder rod 3.
A is slidably provided, and a rack portion 103B is integrally formed at the upper end. This rack section 103
A pinion 105 rotatably supported by the cylinder head 3 is engaged with B, and a rack 106 that is slidable on the cylinder rod 3 is engaged with the opposite side of the pinion 105. Connected operating wire 1
The other end of 07 is connected to a throttle grip 32.

Also, between the rack 106 and the cylinder rod 3, there is a compression coil spring 108 that biases the rack 106 toward the upper left in the figure.
is interposed, and the rack 1 due to this spring 108
A stopper 109 that regulates the amount of movement of the rack 106
It is set in.

In such a configuration, when the throttle grip 32 is operated to the high speed side, the rack 106 is moved against the spring 10B via the operation wire 107, and the pinion 105
The sliding wheel bearing 103 is then moved to the upper left in the figure via the rack portion 103B of the sliding bearing 103. As a result, the rocker arm 101 is also moved upward and to the left via the shaft 102, and the swinging fulcrum of the rocker arm 101 changes, causing the rocker arm 101 to move upward and left.
The abutment position between the cam 101 and the cam 16 changes, and the operating timing of the mirror valve 15 changes, that is, the phase shift with respect to the operating timing of the intake valve 6 is performed. At this time, the phase change caused by the operation of the throttle grip 32 is delayed by a predetermined angle with respect to when the throttle grip 32 is not operated, that is, when the throttle grip 32 is rotating at a low speed, as in each of the above embodiments.

Even in such a third embodiment, the same effects as in the second embodiment can be achieved.

Note that in the third embodiment, locking means for locking the left and right stopping positions of the sliding bearing 103 may be provided, as in the second embodiment.

Further, in carrying out the present invention, the present invention is not limited to the above-mentioned embodiments, and the present invention includes modifications within a range that can achieve the object of the present invention. That is, the number of camshafts for driving each valve is not limited to two or three as in the above embodiments, but may be one.
The drive type of these camshafts is also not limited. Furthermore, although it is not necessarily necessary to provide a variable intake pipe length device and a variable exhaust pipe length device, if both or either one is provided, the characteristics can be further improved. In short, the present invention:
It is sufficient that the mirror valve has a mushroom (poppet valve) shape and has a structure that can shut off intake air in the middle of the intake stroke.

〔Effect of the invention〕

As described above, according to the present invention, there is an effect that the blockage of the intake passage during the intake stroke can be sufficiently sealed with a small driving force.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing a first embodiment of the present invention, FIG. 2 is a schematic configuration diagram showing a phase conversion device used in the first embodiment,
3 is an enlarged view taken along the line ■-■ in FIG. 1, FIG. 4 is a P-V diagram explaining the present invention in detail, and FIG. 5 is a sectional view showing a second embodiment of the present invention. FIG. 6 is a sectional view of essential parts showing a third embodiment of the present invention. 1... Cylinder, 2... Piston, 3... Cylinder head, 4... Intake passage, 4A, 5A... Opening,
4B... Midway opening, 5... Exhaust passage, 6... Intake valve, 7... Exhaust valve, 20... Phase change device forming part of valve drive mechanism, 40... Intake Pipe length variable device, 42... Fixed intake pipe, 43... Movable intake pipe, 46... Servo motor, 47... Control means, 4
8... Engine rotating object detection means, 60... Exhaust pipe length variable device, 62... Fixed exhaust pipe, 65... Movable exhaust pipe, 66... Valve, 75... Servo motor, 90, 1
00: Phase conversion device forming part of the valve drive mechanism.

Claims (1)

[Claims] (1) In an engine that has an intake passage and an exhaust passage that communicate with the cylinder, and mushroom-shaped intake valves and exhaust valves that open and close the openings of these intake passages and exhaust passages to the cylinder, A mushroom-shaped mirror valve for intake timing control that opens and closes the intake passage is provided in the middle of the intake passage, and a valve drive mechanism is provided that causes the mirror valve to close the intake passage before the intake passage is closed by the intake valve. The Miller cycle engine is characterized by: