JP2926458B2 - Variable compression mechanism in reciprocating engine - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[Object of the invention]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reciprocating engine typified by a four-cycle or two-cycle gasoline engine or a diesel engine, and in particular, its compression ratio can be switched according to the operating condition of the engine. It relates to a variable compression mechanism.

[0002]

BACKGROUND OF THE INVENTION For example, in a four-cycle gasoline engine, a piston reciprocates in a cylinder whose one end is closed by a cylinder head, and this movement is output instead of a rotational movement by a crankshaft. The mixture of fuel and air is sucked in by the motion, compressed, burned by spark ignition, and the rotational energy is extracted and exhausted.

At this time, the output of the engine is influenced by how efficiently the air-fuel mixture, which is direct energy, is sucked into the cylinder. Since it varies depending on the mass, the flow velocity, and the like, it is inevitable that a rotation range in which sufficient efficiency cannot be obtained depending on the number of revolutions of the engine occurs.
That is, the apparent theoretical intake air amount matches the cylinder volume, but the actual intake air amount in consideration of the charging efficiency and the like differs depending on the engine speed and the like. For example, if the engine is designed to be a high-speed, high-power type, the intake hole diameter and valve timing are set so that sufficient intake is achieved at high speeds, and the compression ratio is matched to improve combustion efficiency. Is set. In an engine of such a design, in a low-speed operation range, for example, a sufficient flow rate of the intake air-fuel mixture is not generated, and thus a sufficient charging efficiency of the air-fuel mixture is not always obtained. Under the compression ratio calculated as above, sufficient compression cannot be performed, resulting in a substantially low compression state, and good fuel efficiency cannot be expected. In the description of the present specification, a preferable intake air amount obtained, for example, at the time of high rotation described above is defined as an appropriate actual intake air amount. The rotation range of the engine in which the proper actual intake air amount can be obtained is called a suitable rotation range, and the other rotation ranges are called non-suitable rotation ranges.

In view of the above, various variable compression mechanisms have conventionally been proposed in which the compression ratio can be switched according to the engine speed. However, the variable compression mechanism is mechanically complicated, and the mechanism accompanying the switching of the compression ratio. It is unavoidable that such a situation becomes complicated, and there is hardly any such a bottleneck that can withstand practical use.

[0005]

[Technical Issues Attempted to Be Developed] The present invention has been made in view of such a background, and has been developed to develop a novel mechanism which can be realized with a relatively simple configuration when configuring a variable compression mechanism. I tried.

[0006]

Configuration of the Invention

Means for Achieving the Object A first aspect of the variable compression mechanism in the reciprocating engine according to the present invention is that a piston connected to a crankshaft via a connecting rod reciprocates in a cylinder, and performs suction, compression, combustion (expansion). ), An engine that performs each step of exhausting and outputs rotation from the crankshaft. The piston and the connecting rod are connected via an eccentric piston pin, and the eccentric position is set by rotating the eccentric piston pin. selected according to the condition of rotation, in what comprises an eccentric piston pin mechanism that can change the compression ratio, position of the eccentric position
When holding the device, a positive
By contacting the shock absorber body with the eccentric piston pin,
To maintain the rotation posture of the eccentric piston pin.
The changer body is attached to the piston or connecting rod
And the positioner machine attached to these
The position of the positioner body itself is maintained by the structure.
Positioner body position change is provided on the crankcase side.
A variable compression mechanism in a reciprocating engine, which is performed by a controller .

According to a second aspect of the variable compression mechanism in the reciprocating engine according to the present invention, in addition to the above requirements, the eccentric piston pin mechanism causes the piston to die when the proper actual intake air amount of the engine cannot be obtained. The piston is set to a position deviated to the point side, while the piston is set to a position deviated to the bottom dead center side when an appropriate actual intake air amount of the engine is obtained. is there.

[0008] Furthermore, the third invention of the variable compression mechanism in the reciprocating engine according to the present application, in addition to the above requirements,
The rotation of the eccentric piston pin is caused by the force applied to the piston during the compression and combustion steps and the resistance of the connecting rod to the force, while the pulling force of the connecting rod during the suction step and the piston It is characterized by being rotated by the sliding resistance against the force and the urging force of the set spring. The present invention aims to achieve the above object.

[ 0009 ]

According to the present invention , a pair of eccentric piston pins for connecting the piston and the connecting rod are held.
Providing a positioner body having claws;
Contact the eccentric piston pin
The eccentric piston pin
Carry. And maintaining the position of the positioner body itself
Eccentric position
After replacement, the members for operating the positioner body
It is not necessary to keep the
The member for operating the crankcase does not move
Provided on the side. For this reason, move the piston to the connecting rod.
Position relatively biased toward the top dead center or bottom dead center
Can be selected more accurately, and this position
To maintain the compression ratio according to the engine speed range.
Can be performed more accurately.

[ 0010 ]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be specifically described below with reference to the illustrated embodiments. First, FIG. 1 schematically shows an engine E to which the present invention is applied, and shows an embodiment in which a 4-cycle gasoline engine is applied as an example. Of course, as described above, the present invention can be similarly applied to a two-stroke gasoline engine, a two-stroke or four-stroke diesel engine as long as it is a reciprocating engine. First, reference numeral 1 denotes a cylinder, which has a crankcase 2 provided below, a cylinder head 3 provided above, and an upper end side closed by the cylinder head 3. An intake hole 4 and an exhaust hole 5 are provided in the cylinder head 3, and an intake valve 6 and an exhaust valve
Is provided to open and close the space between the fuel cell and the combustion chamber C. Reference numeral 8 denotes a cam for shifting the intake valve 6 and the exhaust valve 7, respectively.
Further, a spark plug 9 is provided between the intake valve 6 and the exhaust valve 7.
Is provided.

Meanwhile, the member code 10 when described in the crank and around the piston provided in the cylinder 1 and the crankcase 2 a crankshaft, the crankshaft 10 via a connecting rod 11 and crank pin 12 at its eccentric position And the connecting rod 1
1 is connected to the piston 13 at a small connecting rod end 14. In the present invention, an eccentric piston pin mechanism 20, which is a main member of the variable compression mechanism 15, is provided between the small connecting rod end 14 and the piston 13. Reference numeral 13a
Is a piston ring, and 13b is a piston side.

[0012] below the variable compression mechanism 15 will be described. The main component is an eccentric piston pin mechanism 2
0, a positioner mechanism 30 and a controller 40. First, the eccentric piston pin mechanism 20 will be described. This mechanism is provided at a connecting portion between the piston 13 and the small connecting rod end 14. First, the eccentric piston pin 21 for connecting the two is connected to the small connecting rod end 14 and the piston. 13 so as to penetrate the piston side 13b. This eccentric piston pin 21 is
a and the connecting rod fitting portion 21b eccentrically, and the amount of eccentricity is D. That is, the eccentric piston pin 21 is provided on the bearing 22a provided on the piston 13 side.
And a bearing 22b provided on the connecting rod 11 side, and are fitted to the piston 13 and the connecting rod small end portion 14, respectively.
2b uses, for example, a so-called retainer type bearing in which a roller of the bearing is held by a holding member.
One of the pair of left and right bearings 22a is supported by the bearing case 23 on the piston side 13b, and the other end is directly supported by the piston side 13b.

[0013] And the end opposite to the side where the bearing case 23 is provided by providing a set spring case 24, here for example, provided the set spring 25, such as a spiral spring, and set spring one end of the set spring 25 The other end is fixed to the eccentric piston pin 21 in the case 24, and the piston 1 is
No. 3 is given a tendency to rotate so as to always deviate toward the top dead center.
Both the bearing case 23 and the set spring case 24 are positioned by the key 26 at the fitting position with respect to the piston 13. Reference numeral 27 denotes a spacer that closes the space between the small end 14 of the connecting rod and the piston 13 on the set spring case 24 side.

[0014] In addition to the eccentric piston pin 21 be one comprising a restricting protrusion 21c in the bearing case 23 side, this compound protrusion receiving portion 23a formed in the bearing case 23, with respect to 23b, substantially at its bottom Rotate 150 °, and the projection receiving portion 23a itself,
A structure is adopted in which further rotation is prevented at the position where it abuts on 23b. As understood from the above description of the eccentric piston pin 21, the relative position between the piston 13 and the connecting rod 11 is switched by a dimension corresponding to almost twice the eccentric amount according to the direction of the eccentric piston pin 21. Incidentally, the rotation angle of the eccentric piston pin 21 is determined in consideration of, for example, obtaining a rotation moment enough to rotate the piston 13 during reciprocation of the piston 13 and obtaining a space for forming the regulating protrusion 21c. The angle is not limited to 150 °, and an appropriate setting is possible.

[0015] Then the eccentric piston pin 21 in the eccentric piston pin mechanism 20 stores the position eccentric, the positioner mechanism 30 for holding explaining. First, the positioner main body 31, which is a main member, includes a pair of angularly projecting holding claws 31a and 31b, a lever-shaped control receiving portion 31c extending downward, a base of the holding claws 31a and 31b, and a control receiving portion 31c. Notch receiving grooves 31d and 31e provided on the side part between the base part and the base part, and these are configured to swing right and left at the center of rotation 31f. The positioner main body 31 is attached, for example, by fitting the hole-shaped rotation center 31f of the positioner main body 31 into a pin 33 of a positioner support 32 mounted inside the piston 13. The positioner support 32 is provided with hole-shaped notch mounting portions 34 on both sides thereof, from which the pointed notches 35 corresponding to the notch receiving grooves 31d and 31e are slidably fitted, and further set. The spring 36 tends to always project toward the positioner main body 31 side.

[0016] will be described controller 40.
This is the positioner body according to the engine speed.
31 is changed so that the eccentric piston pin 2
1 for switching the position of the positioner body 3
Clan that does not move to more accurately change the posture
It is provided on the work case 2 side. And control
The roller 40 has, as an example, a control cam rod 41 with which the control receiving portion 31c of the positioner main body 31 abuts at the bottom dead center of the piston 13 as a main member. The control cam rod 41 is provided with cam portions 41a and 41b at the receiving position of the control receiving portion 31c, and the control cam rod 41 is shifted by the actuator 42 in a direction substantially perpendicular to the sliding direction of the piston 13 as an example. The actuator 42 uses, for example, an electromagnetic solenoid or the like, and receives driving power from an appropriate driver 43 to shift the slider 42a and shift the control cam rod 41. Note that the driver 43
Is controlled by the engine rotation sensor 44. Of course, the engine rotation sensor 44 may be a sensor provided directly on the crankshaft 10, or may be, for example, a sensor that detects an ignition pulse signal for the ignition plug 9 or a sensor that detects rotation of a camshaft. . Further, the actuator 42 is not limited to the one operated by the drive power supply controlled by receiving the output from the engine rotation sensor 44, and may be a linkage shifted by a centrifugal governor or the like according to the engine rotation. No problem.

[0017] The positioner mechanism 30 as described above, notch
The notch 35 which fits into the receiving grooves 31d and 31e and these.
And the like for storing and maintaining the posture of the positioner main body 31.
This is a generic term, and once the eccentric position is switched,
The posture of the positioner body 31 is
Therefore, the controller 40 is always stored and maintained.
It is not necessary to keep operating the positioner body 31
No. Therefore, the eccentric position can be maintained more reliably.
It is intended to maintain the compression ratio more accurately.

I) Engine operating condition The operating condition of the variable compression mechanism of the reciprocating engine according to the present invention will be described below. 3 and 5 to 7 show the operation state, but it can be said in common that the piston 13 is connected to the connecting rod 11 by the rotation of the eccentric piston pin 21 as is apparent from the description of the structure. Is switched relative to the connecting rod small end 14, thereby switching the compression ratio.
Therefore, the connecting rod fitting part 21b of the eccentric piston pin 21 is always located at the center of the small connecting rod end 14, while the piston fitting part 21b of the eccentric piston pin 21 is
The a side switches the center position of the eccentric piston pin 21 up and down by rotation. However, FIG.
In the description of 5 to 7, since the positioner mechanism 30 and the like are attached to the piston 13, the center of the connecting rod small end portion 14, that is, the eccentric piston This is illustrated as a state in which the position of the connecting rod fitting portion 21b on the pin 21 is switched.

Ii) Operation in a suitable rotation range A suitable rotation range is a basic design concept of an applied engine, for example, when high rotation and high power are aimed at,
It means that it is operated in a high-speed range above a certain rotation to meet its purpose. Therefore, depending on the engine characteristics, the switching between the suitable rotation range and the non-conforming rotation range outside the range can be appropriately switched in the range of about 2000 rotations per minute to several thousand rotations per minute as the engine rotation speed. Usually, the compression ratio is lower during the operation in the compatible rotation range than in the non-conforming rotation range.

In this state, as shown in FIG. 3, the piston fitting portion 21a of the eccentric piston pin 21 is located below and the connecting rod fitting portion 21b is located above. That is, the center of the piston fitting portion 21a is P ₀ ,
When the center of the connecting rod fitting portion 21b and P _1, the center P ₁ is clockwise from the vertical above the connecting rod fitting portion 21b from the center P ₀ of the piston engaging portion 21a of the eccentric piston pin 21 as shown in FIG. 3 It is in a state of being located at a predetermined eccentric amount D at a position inclined upward by about 15 °.

Referring to the positioner mechanism 30 in this state, the positioner main body 31 is tilted counterclockwise as a whole in FIG. 3, and at this time, the holding claws 31b act on the regulating protrusions 21c. That is, in the above-mentioned deflecting state of the eccentric piston pin 21, the regulating projection 21 c integral therewith comes into contact with the projection receiving portion 23 b of the bearing case 23 so that further rotation is hindered. That state is maintained by being blocked by the holding claws 31b of the positioner main body 31. At this time, the notch 35 of the positioner main body 31 has left and right notch receiving grooves 31d, 31d.
This state is maintained by selecting and fitting each. In order to set the position of the positioner main body 31, the control cam rod 41 of the controller 40 is shifted to the right in FIG. 3, and the control receiving portion 31c is set to the right by the left cam portion 41a. I have. In such a state, the piston 13 is connected to the connecting rod small end 1 of the connecting rod 11.
4, the combustion chamber C has a sufficient volume at the compression top dead center and apparently has a low compression state.

Iii) Operation in the non-conforming rotation range On the other hand, in the operation in the non-conforming rotation range, the piston 13 is further moved from the small connecting rod end 14 in reverse to the operation in the above-mentioned conformation rotation range.
Is set in a state of being positioned above. That is, as shown in FIG. 5, the eccentric piston pin 21 is in a state rotated by about 150 ° from the previous steady state. At this time, the regulating protrusion 21c comes into contact with the protrusion receiving portion 23a of the bearing case 23, and this state is changed to the holding claw 31 of the positioner body 31 of the positioner mechanism 30.
As a result, the position of the eccentric piston pin 21 is maintained such that a is pressed from below. The positioner body 31 itself maintains its position by the notches 35 being fitted into the notch receiving grooves 31e. A controller 4 for shifting the positioner body 31
5, the control cam rod 41 deviates leftward as shown by the solid line in FIG. 5, and the right cam portion 41 b moves the control receiving portion 31 c of the positioner body 31 in FIG.
It is in a state of being pushed to the left. The respective switching from these two states will be described below.

Iv) Switching from adaptive speed range operation to non-adaptive speed range operation To switch between the two states as described above, the following is performed. First, when the engine rotation sensor 44 detects the engine rotation to be switched, its output signal is supplied to the driver 43, whereby the operating voltage is supplied from the driver 43 to the actuator 42. In the steady state, in the control cam rod 41 in FIG. 3, because it is state of biasing the rightward performs switching from this state
Then, the slider 42a of the actuator 42 moves in the contracting direction. When this is done, the piston 13
When reaching the bottom dead center, as shown in FIG.
The cam 41b of the door 41 is shifted to the right.
The part 31c is moved left and right. At this time, first, as shown in FIG. 6, when the control receiving portion 31c of the positioner main body 31 is pushed in, the positioner main body 31 is rotated clockwise about the rotation center 31f as a whole, and is firstly eccentric by the holding claw 31b. Piston pin 21
The support state of the regulating projection 21c at the point is released. As a result, the eccentric piston pin 21 is at least shown in FIGS.
In the middle, the clockwise rotation is permitted.

When the eccentric piston pin 21 is allowed to rotate freely as described above, switching of the relative position between the piston 13 and the connecting rod 11, which is one of the characteristic features of the present invention, is performed by reciprocating the piston. It is done automatically by using cleverly. That is, the relative piston 1
The operation of switching the connecting rod 3 so as to move upward from below the connecting rod small end 14 of the connecting rod 11 is combustion (expansion).
This is performed in a step other than the step in which the piston moves downward, that is, actually in a suction step. In the following, a description will be given with reference to a schematic diagram showing the rotation operation of the eccentric piston pin 21 shown in FIG. 8. In the suction process, the piston 13 tends to remain at a certain position due to the sliding resistance between the piston ring 13 a and the cylinder 1 and the suction negative pressure. However, since it is in a state where the connecting rod 11 is pulled downward, the center P ₁ of the connecting rod fitting portion in FIG.
Tries to move downward by the connecting rod 11. However, since the center P ₀ of the piston fitting portion can not be moved up and down by rotating the piston engaging portion 21a to the right, FIG. 8
(B) to position the center P ₁ of the connecting rod fitting portion downward as shown. Note that, at any position in the entire region from the top dead center to the bottom dead center of the intake stroke, a line segment connecting the center P ₀ of the piston fitting portion and the center P ₁ of the connecting rod fitting portion, and the connecting rod 11 The piston fitting portion 21a and the connecting rod fitting portion 2 prevent the angle?
By setting 1b and the diameter of the crank, the eccentric piston pin 21 can be rotated.

The position of the eccentric piston pin 21 is automatically switched as described above. Of course, the piston 13 is deviated upward with respect to the connecting rod 11 only by the suction negative pressure and the sliding resistance between the piston ring 13a. In the present invention, a set spring 25 is provided at the other end of the eccentric piston pin 21 in the eccentric piston pin mechanism 20 so that the piston 13 is constantly connected to the connecting rod 11. Is given a tendency to deviate upward. As can be understood from the operation of the set spring 25, the set spring 25 is, besides such a spring, a torsion bar type in which one end is fixed inside the eccentric piston pin 21 and the other end is fixed to the piston 13 side. It can be applied as appropriate.

When the rotation of the eccentric piston pin 21 is switched, for example, at 2000 revolutions per minute, the intake process is performed 1000 times per minute. Therefore, the intake process is performed about 13 times per second. That is, the turn is made virtually instantaneously. At this momentary moment, the regulating projection 21c of the eccentric piston pin 21 is
When the abutment comes into contact with the side of the protrusion receiving portion 23a, the holding claw 31a of the positioner main body 31 is held from below so as to prevent the subsequent movement. At this time, even if the positioner main body 31 is instantaneously switched, the movement of the regulating protrusion 21c itself smoothly contacts the side edge of the holding claw 31b, and therefore moves to the protrusion receiving portion 23a side of the bearing case 23. It does not hinder between them.

The position of the positioner main body 31 can be set to a range where the notch 35 exceeds the boundary between the notch receiving grooves 31d and 31e, and thereafter, the inclined surface between the notch 35 and the notch receiving groove 31e is used. The positioner main body 31 is set in a state deviated clockwise in the figure. Accordingly, if the control cam rod 41 of the controller 40 guides the control cam rod 41 to at least the position where the notch 35 exceeds the boundary convex portion between the notch receiving grooves 31d and 31e of the positioner main body 31 as shown in FIG. 31 stores and maintains the operating posture. In such a state, the eccentric piston pin 2
Reference numeral 1 denotes a state in which the piston 13 is set in a state in which the piston 13 is located relatively above the small end portion 14 of the connecting rod, whereby the apparent size of the connecting rod 11 is increased, and the position of the piston 13 at the top dead center is further increased. Since it is deviated upward, the volume of the combustion chamber C during the compression step is made smaller, and the apparent compression ratio is increased.

V) Switching from non-conforming rev range operation to compliant rev range operation This operation is also performed in reverse, with the same principle as the operating situation already described. That is, in response to the output of the engine rotation sensor 44, the control cam rod 41 is substantially turned off in FIGS.
Shifted to the right. This allows the positioner body 31
Is released from the holding of the restricting projection 21c on the eccentric piston pin 21 held by the holding claw 31a, the eccentric piston pin 21 is allowed to rotate freely. At this time, when undergoing the compression step or the combustion step, the piston 13 is connected to the connecting rod small end portion 14.
As a result, the eccentric piston pin 21 is automatically rotated.

The turning operation of the eccentric piston pin 21 will be described with reference to the schematic diagram of FIG.
High pressure combustion gas works to push down the piston,
For receiving the drag of the connecting rod 11, by positioning the center P ₁ of the connecting rod fitting portion upward, the center P ₀ of the piston engaging portion is going down. That is, FIG.
The state shown in FIG. 8A is to be shifted from FIG. 8B, and the eccentric piston pin 21 rotates as a whole.
Note that, at any position in the entire range from the top dead center to the bottom dead center of the combustion stroke, the line connecting the center P ₀ of the piston fitting portion and the center P ₁ of the connecting rod fitting portion and the connecting rod 11 If the diameter of the piston fitting portion 21a, the connecting rod fitting portion 21b, and the diameter of the crank are set so that the angle α sandwiched between them does not become 180 degrees, the eccentric piston pin 2
1 can be rotated.

On the other hand, the same operation as described above is performed in the compression step. That is, in the compression step, the piston compresses the air-fuel mixture as it rises and receives the pressure. At this time, a force to move the center P ₀ of the piston fitting portion downward is exerted. However, the piston fitting portion 21 a itself cannot slide up and down in the piston 13, so that the center P ₀ of the connecting rod fitting portion is not moved.
Work to position ₁ upward. Eccentric piston pin 21 as a result rotates leftward, the center P ₁ of the connecting rod fitting portion is positioned above the center P ₀ of the piston fitting portion.

Note that, over the entire compression stroke, the angle α
Is sharper than the angle α at the time of the combustion stroke, and the center P ₁ of the connecting rod fitting portion is easily moved upward from the center P ₀ of the piston fitting portion. The pressure of the air-fuel mixture does not reach the position where the eccentric piston pin 21 is rotated at a position closer to the bottom dead center than the middle of the compression stroke. Therefore, the rotation of the eccentric piston pin 21 is performed between the middle and the top dead center. As a result, the regulating protrusion 21c comes into contact with the protrusion receiving portion 23a of the bearing case 23 from below. And, as described above, the positioner body 31
7 rotates in the counterclockwise direction in FIG. 7, so that the holding claw 31a holds the regulating projection 21c abutting on the projection receiving portion 23a so as to support the regulating projection 21c from below. At this time, the notch 35 is fitted in the notch receiving groove 31d, and its position is stored and maintained .

Vi) Other switching settings In the above-described embodiment, the compression ratio is set to high compression during low-speed operation as a non-conforming rotation range, and the compression ratio is set to low compression during high-speed operation as a suitable rotation range. The embodiment is effective in a naturally aspirated engine, a super-aspirated engine using a turbocharger, a supercharger, or the like. However, other settings may be used in consideration of compatibility with other mechanisms. That is, it is possible to set the compression ratio to be increased in the high-speed rotation range or the middle-speed rotation range. For example, in order to increase the thermal efficiency of the engine, at a certain stage of the engine speed (for example, when the vehicle speed is 60 to 100 km / h), in the case of an engine having a variable valve timing device, the intake valve is intentionally closed earlier to shorten the intake stroke. However, if the exhaust valve is left open, the expansion stroke becomes longer than the intake stroke, so that expansion energy can be more effectively taken out and the thermal efficiency is improved. Therefore, in this case, instead of biasing the piston toward the top dead center at low speed, the actual compression ratio is made the same by the intentional reduction of the intake air amount in the medium speed rotation range (the compression gap is reduced). To do)
The piston is biased toward the top dead center.

Vii) Consideration on Strength In the present invention, the switching state of the relative mounting position between the piston 13 and the connecting rod 11 is determined by the positioner body 3.
The strength is maintained by the eccentric piston pin 21 within a range of approximately 150 °, so that the combustion pressure of the air-fuel mixture that acts vertically in the eccentric piston pin 21 once set is maintained. The eccentric piston pin 21 is rotated, and the holding claw 31 of the positioner main body 31 is further rotated.
a, 31b works in the direction of compressing (buckling direction),
Since it is almost along the load direction of the connecting rod 11,
There is no component force enough to break the holding claws 31a, 31b.

[0034]

[Other Embodiments] The present invention is based on the above-described structure as one basic embodiment. In essence, the eccentric piston pin 21 is held at an eccentric position by a positioner body 31. In addition, the rotation of the eccentric piston pin 21 is automatically switched by utilizing the movement of the reciprocating piston 13 and the connecting rod 11, and as long as the rotation is, for example, the controller 40 or the like can take various embodiments. That is, in the embodiment shown in FIG. 11, the positioner main body 31 is not of a swing type but of a sliding type.
The positioning is achieved. Further, such a positioner main body 31 is not necessarily required to be attached to the piston 13, and may be attached to the connecting rod 11. That is, as shown in FIG. 12A, the positioner main body 31 is attached to the connecting rod 11 so as to be swingable.

[0035] Further, the controller 40 of the pair of pin type in the crankcase 2 side as is also shown in Figure 13 for the controller 40 for shifting the positioner body 31
A and 40B may be used. That is, in this embodiment, hydraulic cylinders which come and go mutually according to the engine speed are used as the controllers 40A and 40B. Note that
In this manner, the controller for changing the attitude of the positioner body 31 is used.
Even if hydraulic pressure is applied to the roller 40, the controller 40 itself
Is fixedly provided on the crankcase 2 side.
Operating the pin type controllers 40A and 40B.
The oil pressure itself is always constant regardless of the rotation of the engine E.
Stable at any time, ensuring the position change of the positioner body 31
Can be done.

[ 0036 ]

According to the present invention, first, a pair of holding claws 31 are provided.
a, the eccentric fixer
Eccentric piston pin
In order to maintain the rotating posture of 21, the piston
13 and impact force applied through the eccentric piston pin 21
This makes it possible to design a device capable of withstanding the above. Switching of compression ratio
The operation of the positioner body 31 for
Driven by controller 40 provided on case 2 side
Without moving the controller 40 all the time.
Positioner body 31
You can switch. Furthermore, the position after switching once
The notch 35 and the notch receiving groove 31
d, 31e, etc. maintained by the positioner mechanism 30.
Therefore, for example, by continuing to operate the controller 40,
There is no need to maintain the position of the positioner body 31. Soshi
Comprehensively, more reliably the compression ratio according to the applicable rotation range
Not only can you choose, but also maintain this compression ratio more accurately.
Things.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional front view schematically showing an engine to which a variable compression mechanism of the present invention is applied.

FIG. 2 is an enlarged longitudinal side view showing a characteristic portion of the above.

FIG. 3 is a vertical sectional front view showing a state in which the piston is biased toward a bottom dead center side.

FIG. 4 is a transverse sectional view showing the internal structure of the piston.

FIG. 5 is a longitudinal sectional front view showing a state where the piston is deviated to the top dead center side.

6 is a vertical sectional front view showing a state where the state of FIG. 3 is shifted to a state in which holding of a holding claw is released by an operation of a controller.

7 is a vertical sectional front view showing a state where the state of FIG. 5 is shifted to a state in which holding of the holding claws is released by the action of the controller.

FIG. 8 is a schematic diagram showing a rotation operation of the eccentric piston pin in comparison with a case where the piston is at the bottom dead center side and a case where the piston is at the top dead center side.

FIG. 9 is an exploded perspective view showing the variable compression mechanism of the present invention.

FIG. 10 is an exploded perspective view showing a set spring and a set spring case that give a rotation tendency to the eccentric piston pin.

FIG. 11 is a longitudinal sectional front view and a longitudinal sectional side view showing an embodiment in which a positioner main body is of a sliding type.

FIG. 12 is a longitudinal sectional side view and a longitudinal sectional front view showing an embodiment in which a positioner main body is attached to a connecting rod.

FIG. 13 is a longitudinal sectional front view showing another embodiment of the controller for shifting the positioner main body.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Cylinder 2 Crankcase 3 Cylinder head 4 Intake hole 5 Exhaust hole 6 Intake valve 7 Exhaust valve 8 Cam 9 Ignition plug 10 Crankshaft 11 Connecting rod 12 Crankpin 13 Piston 13a Piston ring 13b Piston side 14 Small end of connecting rod 15 Variable compression mechanism Reference Signs List 20 eccentric piston pin mechanism 21 eccentric piston pin 21a piston fitting part 21b connecting rod fitting part 21c regulating projection 22a bearing (piston side) 22b bearing (conrod side) 23 bearing case 23a projection receiving part 23b projection receiving part 24 set spring case 25 Set spring 26 Key 27 Spacer 30 Positioner mechanism 31 Positioner main body 31a Holding claw 31b Holding claw 31c Control receiving portion 31d Notch receiving groove 31e Notch receiving groove 3 1f Center of rotation 32 Positioner support 33 Pin 34 Notch mounting part 35 Notch 36 Set spring 40 Controller 40A Controller 40B Controller 41 Control cam rod 41a Cam part 41b Cam part 42 Actuator 42a Slider 43 Driver 44 Engine rotation sensor α Angle C Combustion Chamber D Eccentricity E Engine P ₀ Center of piston fitting part P ₁ Center of connecting rod fitting part

Claims (3)

(57) [Claims] A piston connected to a crankshaft via a connecting rod reciprocates in a cylinder to perform suction, compression, combustion (expansion), and exhaust processes, and output rotation from the crankshaft. The piston and the connecting rod are connected via an eccentric piston pin, and by rotating the eccentric piston pin, an eccentric position can be selected according to the condition of engine rotation, and a compression ratio can be changed. smell which comprises an eccentric piston pin mechanism to
In maintaining the position of the eccentric position,
Eccentric fixation of the positioner body with a pair of holding claws
Contact with the eccentric piston pin.
Maintain the rotation posture and the positioner body
Or connecting rod
Positioner body with positioner mechanism attached to
The posture of the positioner itself is maintained, and the posture of the positioner body changes.
Is changed by the controller provided on the crankcase side.
Variable in the reciprocating engine characterized by
Compression mechanism. 2. The eccentric piston pin mechanism sets a piston at a position deviated to a top dead center side when an appropriate actual intake amount of the engine cannot be obtained, while an appropriate actual intake amount of the engine is 2. A variable compression mechanism in a reciprocating engine according to claim 1, wherein the piston is set at a position deviated to the bottom dead center side when it can be obtained. 3. The rotation of the eccentric piston pin is caused by the force applied to the piston during the compression and combustion steps and the resistance of the connecting rod to the force, while the pulling force of the connecting rod during the suction step. 3. The variable compression mechanism of a reciprocating engine according to claim 1, wherein the piston is rotated by a sliding resistance of the piston against the force and an urging force of a set spring.