JP2004346848A - Variable compression ratio mechanism for internal combustion engine - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve the certainty and durability in switching a compression ratio in a variable compression ratio mechanism of an internal combustion engine. <P>SOLUTION: This variable compression ratio mechanism has a bush part wherein an outer diameter part and an inner diameter part are decentered from each other, a rotatable control plate as a flange part of the bush part, a first lock part mounted on the control plate to fix the same to a first peripheral position for a first compression ratio of the internal combustion engine, and a second lock part mounted on the control plate to fix the same on a second peripheral position for a second compression ratio different from the first compression ratio. Further a first projecting part is formed on a surface opposite to the control plate, of a crank shaft in a state of being engaged with the first lock part to forcibly rotate an eccentric bearing with a crank shaft through the control plate, and a second projecting part is formed on a surface opposite to the control plate, of a connecting rod large end part in a state of being engaged with the second lock part to fix the eccentric bearing to the connecting rod large end part though the control plate. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention belongs to the technical field of a variable compression ratio mechanism of an internal combustion engine mounted on an automobile or the like, and more specifically, to the technical field of a variable compression ratio mechanism capable of changing a compression ratio by changing a piston stroke.
[0002]
[Prior art]
In this type of variable compression mechanism, by increasing the piston stroke, the volume of the combustion chamber at the compression top dead center is reduced to increase the compression ratio (hereinafter, appropriately referred to as “high compression ratio state”). By shortening the piston stroke, the volume of the combustion chamber at the compression top dead center is increased to reduce the compression ratio (hereinafter, appropriately referred to as “low compression ratio state”). By setting the high compression ratio state, it is possible to increase the thermal efficiency and increase the output of the internal combustion engine in the middle load range or below and at the low and medium rotation range. Can be suppressed. As a variable compression ratio mechanism for switching the compression ratio in this way, there is a variable compression ratio mechanism provided with an eccentric bearing at a large end of a connecting rod and a lock means for fixing rotation of the eccentric bearing.
[0003]
For example, in Patent Literature 1, an eccentric bearing is inserted between a large end of a connecting rod (a connecting rod or a connecting rod) and a crankpin of a crankshaft. Relatively rotate by dragging. Here, "relative rotation" means that when the rotation of the eccentric bearing is not fixed by the locking means, it is basically dragged by the rotational inertia moment of the crankshaft and rotates in the same direction as the rotation of the crankshaft. It is to be. However, the eccentric bearing rotates while being dragged by the crankshaft, but does not rotate with the crankshaft. Here, when the state is switched to the high compression ratio state, the rotation of the eccentric bearing having the flange portion with the engaging hole, which is an example of the locking means, is rotated by another example of the locking means provided on the crank journal of the crankshaft. Is engaged with the above-mentioned engagement hole and fixed at a predetermined position in the circumferential direction. As a result, the piston stroke is maximized, and the compression ratio is switched to a high compression ratio.
[0004]
[Patent Document 1]
Japanese Utility Model Publication No. Hei 3-13440
[Patent Document 2]
JP-A-6-241058
[Patent Document 3]
JP-A-6-241057
[Patent Document 4]
JP-A-5-302530
[Patent Document 5]
JP-A-11-62647
[0005]
[Problems to be solved by the invention]
However, the conventional locking means including, for example, a lock pin and an engagement hole disclosed in Patent Document 1 described above has a technical problem that the reliability and durability of switching the compression ratio are low. .
[0006]
Specifically, when the internal combustion engine is rotating at high speed, the rotational speed of the crankshaft increases and the rotational speed of the relative rotation of the eccentric bearing also increases. In the conventional configuration in which the lock pin is engaged with the lock pin in a short period of time, the lock pin cannot pass through the engagement hole to engage with the lock pin, and switching of the compression ratio is likely to fail. Therefore, there is a technical problem that the reliability of switching the compression ratio is low. Further, if this is to be solved by increasing the hydraulic pressure applied to the lock pin, the contact surface between the lock pin and the portion other than the engagement hole and the contact surface between the eccentric bearing and the crank pin are severely worn. Therefore, there is also a technical problem that is almost or completely impossible in practice.
[0007]
Alternatively, in the conventional configuration, at the moment when the lock pin is engaged with the engagement hole, there is no mechanism for completely matching the position of the lock pin and the engagement hole, and the lock pin is displaced obliquely with respect to the engagement hole. There is a high possibility of being inserted. Therefore, the lock pin wears the vicinity of the entrance of the engagement hole. Even if the lock pin is engaged with the engagement hole, the lock pin has a small area with respect to the shear force generated in the tangential direction of the relative rotation of the eccentric bearing. There is a technical problem that it is easy to perform and has low durability.
[0008]
Therefore, the present invention has been made in view of the above-described problems, and for example, in a variable compression ratio mechanism of an internal combustion engine, a variable compression ratio of an internal combustion engine capable of increasing the reliability and durability of switching the compression ratio It is an object to provide a mechanism.
[0009]
[Means for Solving the Problems]
The gist of the present invention is that, in a variable compression ratio mechanism of an internal combustion engine, a first or second lock portion of a control plate provided as a flange portion of a bush portion constituting an eccentric bearing and a first protrusion or a connecting rod of a crankshaft. The compression ratio is switched by bringing the end portion into contact with the second protrusion, and hooking the first or second protrusion to the first or second lock portion.
[0010]
In order to solve the above-mentioned problems, the variable compression ratio mechanism for an internal combustion engine according to the present invention is configured such that (i) an outer diameter portion internally fitted to a large end of a connecting rod and an inner diameter portion externally fitted to a crankpin are eccentric to each other. (Ii) a control plate capable of reciprocating along the rotation center line direction of the bush portion and being rotatable integrally with the bush portion as a flange portion of the bush portion; A control plate for fixing the control plate, together with the bush portion, to the connecting rod large end portion and the crankshaft at a first circumferential position for a first compression ratio of the internal combustion engine. A lock portion, and (iv) a second circumferential position for the second compression ratio different from the first compression ratio together with the bush portion, the control plate being provided on the control plate. An eccentric bearing having a second lock portion for fixing the control plate and a surface facing the control plate of the crankshaft, wherein when the control plate moves to a side away from the bush portion, A first projection that is hooked on the first lock portion so as to forcibly rotate the eccentric bearing together with the crankshaft via a control plate, and a surface facing the control plate at a large end of the connecting rod; When the control plate moves to the side approaching the bush portion, a second protrusion that is hooked on the second lock portion so as to fix the eccentric bearing to the large end of the connecting rod via the control plate. Is provided.
[0011]
According to the variable compression ratio mechanism of the internal combustion engine of the present invention, during its normal operation, the linear motion of the connecting rod reciprocating in the cylinder is converted into the rotational motion of the crankshaft by the link mechanism, as is well known. The eccentric bearing is inserted between the large end of the connecting rod and the crankpin of the crankshaft, and basically rotates relatively with the rotation of the crankshaft.
[0012]
Here, when the switching to the first compression ratio is performed, the first circumferential position, for example, the thickest portion of the bush portion of the eccentric bearing (hereinafter, appropriately referred to as “the thickest portion of the eccentric bearing”), The first eccentric bearing and the control plate are configured such that the first lock portion of the control plate located at the first position is abutted against the first protrusion of the crankshaft so that the first lock portion is hooked on the first protrusion. Forced rotation with the shaft. Here, the "forced rotation" according to the present invention is different from the "relative rotation", in which the eccentric bearing has the first lock portion of the control plate in the eccentric bearing butted against the first projection of the crankshaft. Thus, the first lock portion receives the force from the crankshaft and is forcibly rotated together with the crankshaft while being hooked on the first protrusion. Therefore, when the first projection of the crankshaft comes to the position of the top dead center together with the crankshaft, the first projection of the crankshaft abuts on the first projection of the control plate and the first circumferential direction. The connecting rod enters the compression stroke while the position, for example, the thickest portion of the eccentric bearing is positioned on the cylinder side, that is, in the upward direction of the crankshaft (hereinafter, this state is appropriately referred to as “long stroke setting state”). Thereby, the piston stroke becomes the longest, and the first compression ratio state, for example, the high compression ratio state is realized.
[0013]
On the other hand, when the switching to the second compression ratio is performed, it is located at the second circumferential position, for example, the thinnest portion of the bush portion of the eccentric bearing (hereinafter, appropriately referred to as “the thinnest portion of the eccentric bearing”). The relative rotation of the eccentric bearing is stopped by the second lock portion of the control plate being abutted against and hooked on the second protrusion of the large end of the connecting rod. Therefore, when the second projection of the large end of the connecting rod comes to the position of the top dead center together with the crankshaft, the second projection of the large end of the connecting rod is abutted against the second locking part of the control plate and is hooked. With the second circumferential position, for example, a state in which the thinnest portion of the eccentric bearing is located on the cylinder side, that is, in the upward direction of the crankshaft (hereinafter, this state is appropriately referred to as a “short stroke setting state”), the connecting rod performs the compression stroke. By entering, the piston stroke becomes the shortest, and the second compression ratio state, for example, the low compression ratio state is realized.
[0014]
As described above, the switching to the first compression ratio or the second compression ratio, for example, the high compression ratio or the low compression ratio is performed.
[0015]
Therefore, according to the variable compression ratio mechanism of the internal combustion engine of the present invention, it is possible to increase the reliability and durability of switching the compression ratio as compared with the conventional locking means including a lock pin and an engagement hole. is there.
[0016]
Specifically, when the internal combustion engine is operating at a high speed, the rotation speed of the crankshaft increases and the rotation speed of the relative rotation of the eccentric bearing also increases. In the conventional configuration in which the lock pin is engaged with the mating hole, the lock pin cannot pass through the engagement hole and be engaged in a short time in a moment, and there is a high possibility that switching of the compression ratio fails. Further, for example, if this is to be solved by increasing the hydraulic pressure applied to the lock pin, if the contact surface between the lock pin and the portion other than the engagement hole and the contact surface between the eccentric bearing and the crank pin are worn, etc. Is so intense that practically almost or completely impossible. On the other hand, according to the variable compression ratio mechanism of the internal combustion engine of the present invention, regardless of the rotational speed of the relative rotation of the eccentric bearing, for example, the hydraulic pressure of the lubricating oil is adjusted under the control of the electronic control unit, so that the control is performed. Since the second lock portion of the plate is caused to abut against the second protrusion of the large end of the connecting rod and hooked, problems such as meshing and a problem in which the conventional lock pin is obliquely displaced and inserted into the engagement hole, and the like. Since there is little or no possibility of occurrence, the failure of switching the compression ratio can be almost or completely eliminated. Therefore, it is possible to increase the certainty of switching the compression ratio.
[0017]
Further, for example, in the case of the operating state of the internal combustion engine in which the relative rotation of the eccentric bearing is almost or completely stopped, according to the conventional locking means including the lock pin and the engaging hole, the inertia of the relative rotation is left. If the relative rotation is stopped, the compression ratio cannot be almost or completely changed. On the other hand, according to the variable compression ratio mechanism of the internal combustion engine of the present invention, even if the relative rotation of the eccentric bearing is stopped, for example, the hydraulic pressure of the lubricating oil is adjusted under the control of the electronic control unit, so that the crankshaft is controlled. During the rotation of at least one rotation, the first locking portion of the control plate is abutted against the second protrusion of the crankshaft, and the eccentric bearing is forcibly rotated together with the crankshaft in a hooked state, so that the compression ratio is switched. Can be almost or completely eliminated. Therefore, it is possible to increase the certainty of switching the compression ratio.
[0018]
Alternatively, in the conventional configuration, at the moment when the lock pin is engaged with the engagement hole, there is no mechanism for completely matching the position of the lock pin and the engagement hole, and the lock pin is displaced obliquely with respect to the engagement hole. There is a high possibility of being inserted. Therefore, the lock pin wears the vicinity of the entrance of the engagement hole. Even if the lock pin is engaged with the engagement hole, the lock pin has a small area with respect to the shear force generated in the tangential direction of the relative rotation of the eccentric bearing. Easy to do and low durability. On the other hand, according to the variable compression ratio mechanism of the internal combustion engine of the present invention, the first or second lock portion of the control plate and the first protrusion of the crankshaft or the second protrusion of the large end of the connecting rod are hooked by abutment. Therefore, little or no abrasion occurs due to the problem of the engagement and the problem that the conventional lock pin is inserted obliquely in the engagement hole. Therefore, the durability of switching the compression ratio can be improved.
[0019]
In particular, the operation state of the internal combustion engine in which the relative rotation of the eccentric bearing stops almost or completely will be described in more detail. As described above, the eccentric bearing basically rotates relative to the rotation of the crankshaft. Further, as is well known, the connecting rod makes a linear motion reciprocating in a cylinder (not shown) while the crankshaft makes a rotary motion. For this reason, depending on the direction of the external force that the eccentric bearing receives from the connecting rod, there is a case where a moment for rotating the eccentric bearing in the forward or reverse direction is momentarily or continuously applied to the eccentric bearing. Here, "forward rotation" means that the relative rotation of the eccentric bearing is further rotated in the same direction as the rotation direction of the crankshaft. Such a moment is inevitable for a reciprocating engine. Here, when the eccentric bearing is switched from the long stroke setting state to the short stroke setting state or vice versa, depending on the timing of this switching, the eccentric bearing may be rotating during its relative rotation. However, there is a risk that the motor will rotate backward even for a moment. Therefore, when a moment is applied to reversely rotate the eccentric bearing from the connecting rod, the moment of relative rotation is canceled by the rotational inertia moment of the crankshaft, and the relative rotation of the eccentric bearing and the control plate is almost or completely stopped. An operating state of the internal combustion engine that occurs is generated. Here, depending on the switching timing described above, the eccentric bearing may further rotate forward while it is rotating forward. Therefore, in addition to the rotational moment of inertia of the crankshaft, an operating state of the internal combustion engine occurs in which the eccentric bearing and the control plate rotate faster than the crankshaft due to the moment of rotating the eccentric bearing forward from the connecting rod. I do.
[0020]
As described above, according to the variable compression ratio mechanism of the internal combustion engine of the present invention, for example, the relative rotation of the eccentric bearing is almost or completely stopped, or the relative rotation of the eccentric bearing is faster than the engine rotation. Even in a specific operating state of the internal combustion engine, it is possible to increase the reliability and durability of switching the compression ratio.
[0021]
In one aspect of the variable compression ratio mechanism of the internal combustion engine of the present invention, the first lock portion is in a position or shape where the second protrusion is not caught when the control plate moves to the side approaching the bush portion. The second lock portion is provided at a position or shape where the first protrusion does not catch when the control plate moves away from the bush portion.
[0022]
According to this aspect, for example, only the first protrusion of the crankshaft corresponding to the first lock can contact the first lock, and the second protrusion of the large end of the connecting rod that does not correspond to the first lock. A dent or the like is provided so as not to hit. Similarly, only the second protrusion of the large end of the connecting rod corresponding to the second lock can abut on the second lock, but not the first protrusion of the crankshaft that does not correspond. , Dents and the like are provided.
[0023]
As a result, it is possible to further increase the certainty of switching the compression ratio due to the physical structure.
[0024]
In another aspect of the variable compression ratio mechanism for an internal combustion engine of the present invention, the variable compression ratio mechanism is provided on at least one of the connecting rod large end portion and the crankshaft. Drive means is further provided for moving the control plate to a side away from the bush portion and, when the oil pressure is lower than a set value, moving the control plate to a side closer to the bush portion.
[0025]
According to this aspect, switching of the compression ratio is performed, for example, by adjusting the opening of the solenoid valve under the control of an electronic control unit (ECU) which constitutes an example of a driving unit. Is adjusted, and the oil pressure of the lubricating oil is adjusted. Under the control of the ECU, the oil pressure of the lubricating oil is increased, so that the control plate is moved away from the bush portion. On the other hand, under the control of the ECU, the oil pressure of the lubricating oil is reduced, so that the control plate is moved. It is moved to the side approaching the bush portion. The timing of increasing or decreasing the oil pressure of the lubricating oil and the adjustment amount of the oil pressure are uniquely determined from acquisition from a map table created in advance or calculation by a predetermined function.
As a result, for example, the compression ratio can be switched at an appropriate time under the control of the ECU, and the compression ratio can be smoothly switched due to the hydraulic control.
[0026]
In another aspect of the variable compression ratio mechanism of the internal combustion engine of the present invention, the first lock portion is provided on the opposite side of the rotation center line of the inner diameter portion with respect to the rotation center line of the outer diameter portion, The second lock portion is provided at a position facing the first lock portion across the rotation center line, the first circumferential position is for a high compression ratio, and the second circumferential position is For low compression ratio.
[0027]
According to this aspect, in order to realize a high compression ratio, the first lock portion hooked on the first protrusion of the crankshaft is provided with the thickest portion of the bush portion of the eccentric bearing, that is, the thickest eccentric bearing. The control plate is assembled to position the part. On the other hand, in order to realize a low compression ratio, the second lock portion hooked on the second protrusion at the large end of the connecting rod is positioned opposite to the first lock portion across the rotation center line of the outer diameter portion, that is, The eccentric bearing is provided at the thinnest portion of the bush portion, that is, at the thinnest portion of the eccentric bearing.
[0028]
As a result, the compression ratio can be reliably switched between high and low.
[0029]
Note that, in accordance with the characteristics required for the internal combustion engine, a configuration reverse to this embodiment may be adopted. Further, in this aspect, it is possible to switch to a compression ratio in two stages of height using the thickness of the bush portion of the eccentric bearing, but to switch to a compression ratio of three or more stages using the thickness of the bush portion. You may comprise.
[0030]
In another aspect of the variable compression ratio mechanism for an internal combustion engine of the present invention, a protruding portion that can protrude radially of the outer diameter portion is further provided on an inner peripheral surface of the large end portion of the connecting rod that is fitted to the outer diameter portion. And the outer diameter portion includes a wall portion defining an engagement hole with which the protrusion can be engaged.
[0031]
According to this aspect, in order to more reliably switch the compression ratio, the engagement hole and the outer diameter portion of the eccentric bearing are formed on the outer peripheral surface of the outer diameter portion of the eccentric bearing fitted inside the large end of the connecting rod. A protruding portion is newly added as a component on the inner peripheral surface of the large end of the connecting rod to be externally fitted.
[0032]
In these components, specifically, the projections engage with the engagement holes and maintain the engagement state. Therefore, the rotation direction and the rotation range of the rotation of the eccentric bearing are likely to be constrained within the specified range maintaining this engaged state. Here, the "specified range" is a range of relative rotation of the eccentric bearing determined by the shape of the engagement hole, as described later in detail.
[0033]
It is also possible to provide such a protruding portion on the outer diameter portion side and to provide an engagement hole on the inner peripheral surface side of the large end of the connecting rod. Further, only one or a plurality of such a pair of protrusions and engagement holes may be provided for one eccentric bearing.
[0034]
According to this aspect, for example, even when the eccentric bearing and the control plate continue to rotate at a higher speed than the rotation of the crankshaft, the rotation direction and the rotation range of the eccentric bearing are likely to be constrained within a prescribed range, so that at least one crankshaft is provided. During rotation, the first locking portion of the control plate can be abutted against the first projection of the crankshaft and hooked.
[0035]
Further, for example, even when the rotation of the eccentric bearing and the control plate is almost or completely stopped, the rotation direction and the rotation range of the eccentric bearing are likely to be restricted within a specified range. By being constrained at the position on the side or the other end, it is easy to cause the second lock portion of the control plate to abut against the second protrusion of the large end of the connecting rod and to be hooked.
[0036]
As described above, according to this aspect, even in a specific internal combustion engine operating state, for example, the relative rotation of the eccentric bearing almost or completely stops or the relative rotation of the eccentric bearing is faster than the engine rotation. In addition, it is possible to more reliably switch the compression ratio.
[0037]
In the aspect according to the projecting portion, the projecting portion is disposed inside another hole formed in the inner peripheral surface of the connecting rod large end, and the spring is capable of expanding and contracting in the radial direction. The ball may be configured to include a ball disposed on the distal end side and urged to the outside of the other hole by the spring.
[0038]
With such a configuration, the rotation direction and the rotation range of the rotation of the eccentric bearing are likely to be restricted within the specified range. However, the protruding portion may be constituted by another elastic body and a hydraulic or electric valve.
[0039]
The operation and other advantages of the present invention will become more apparent from the embodiments explained below.
[0040]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, a specific embodiment of a variable compression ratio mechanism for an internal combustion engine according to the present invention will be described with reference to the drawings.
[0041]
(1st Embodiment)
The configuration and operation of the variable compression ratio mechanism of the internal combustion engine according to the first embodiment will be described in detail with reference to FIGS.
[0042]
First, the configuration of the first embodiment will be described in detail with reference to FIGS. Here, FIG. 1 is a schematic front view showing the operation of the eccentric bearing, the large end of the connecting rod, and the crankshaft according to the present embodiment. FIG. 2 is an enlarged schematic cross-sectional view of the configuration of the crankshaft, crankpin, connecting rod large end, eccentric bearing, and hydraulic piston according to the first embodiment. FIG. 3A is a schematic exploded perspective view of the eccentric bearing according to the present embodiment. FIGS. 3B and 3C are schematic perspective views in which the control plate lock portion of the eccentric bearing is enlarged.
[0043]
The variable compression ratio mechanism of the internal combustion engine according to the first embodiment shown in FIGS. 1 to 3 is roughly provided with an eccentric bearing 1, a crankshaft 2, and a connecting rod (connecting rod) 4.
[0044]
The eccentric bearing 1 includes an eccentric bearing groove 1a, an eccentric bearing hydraulic chamber 1b, a bush portion 1d, an eccentric bearing thickest portion 1e, an eccentric bearing thinnest portion 1f, a control plate 6, a control plate protrusion 6a, and the present invention. A control plate lock portion 6b forming an example of a “second lock portion”, a control plate lock portion 6c forming a control example of a “first lock portion” according to the present invention, a control plate recess 6d, and a control plate recess 6e. Have been.
[0045]
The crankshaft 2 includes a crankshaft hydraulic passage 2a, a crankshaft hydraulic passage 2b, a crankshaft protrusion 2c that constitutes an example of the “first protrusion” according to the present invention, a crankshaft hydraulic chamber 2d, a crankpin portion 3, and a crankshaft. It is provided with a pin portion hydraulic passage 3a, a hydraulic piston 7 and a spring 8.
[0046]
The connecting rod 4 is configured to include a connecting rod large end 5, a connecting rod large end base hole 5a, and a connecting rod large end protrusion 5b that constitutes an example of the "second protrusion" according to the present invention.
[0047]
Next, a schematic operation of switching the compression ratio of the variable compression ratio mechanism of the internal combustion engine according to the present embodiment will be described with reference to FIGS.
[0048]
As is well known, a linear motion of the connecting rod 4 reciprocating in a cylinder (not shown) is converted into a rotary motion of the crankshaft 2 by the link mechanism. The eccentric bearing 1 is inserted between the large connecting rod end 5 and the crankpin 3. The eccentric bearing 1 basically rotates relative to the rotation of the crankshaft 2. The arrow in the counterclockwise direction indicates the rotation direction of the crankshaft, “ΔD” indicates the rotation diameter of the crankshaft 2, and “Sn” indicates the center of the circumference of the outer diameter portion of the eccentric bearing 1 and the inner diameter. Indicates the distance from the center of the circumference of the part. FIG. 1 shows a state in which a piston (not shown) and a connecting rod 4 are at a bottom dead center.
[0049]
Here, in the present embodiment, when the switching to the high compression ratio is performed, that is, when the control plate protrusion 6a is mainly pressed by the hydraulic pressure of the eccentric bearing hydraulic chamber 1b, the control plate 6 is separated from the bush 1d. When it moves to the crankshaft 2 side, the control plate lock portion 6c located at the thickest portion 1e of the eccentric bearing is abutted against the crankshaft protrusion 2c. Thus, the eccentric bearing 1 and the control plate 6 are forcibly rotated together with the crankshaft 2 in a form in which the control plate lock portion 6c is hooked on the crankshaft protrusion 2c that rotates as a part of the crankshaft 2. Therefore, when the crankshaft protrusion 2c comes to the position of the top dead center together with the crankshaft 2, the control plate lock portion 6c and the thickest portion 1e of the eccentric bearing, which are abutted and caught by the crankshaft protrusion 2c, are illustrated. When the connecting rod 4 enters the compression stroke while the cylinder is not positioned, that is, in the upper position in FIG. 1, that is, while the long stroke is set, the piston stroke becomes the longest, that is, “ΔD + Sn + Sn”, and the high compression ratio state Is realized.
[0050]
On the other hand, when switching to a low compression ratio is performed, that is, when the control plate 6 is mainly pushed by the spring 8 and moves to the bush portion 1d side, the crankshaft protrusion 2c first comes off from the control plate lock portion 6c. Further, the control plate lock portion 6b located at the thinnest portion 1f of the eccentric bearing is abutted against the connecting rod large end projection 5b. Accordingly, the relative rotation of the eccentric bearing 1 is stopped in a state where the control plate lock portion 6b is hooked on the connecting rod large end protruding portion 5b. Therefore, when the connecting rod large end protrusion 5b comes to the position of the top dead center together with the crankshaft 2, the control plate lock portion 6b and the thinnest portion of the eccentric bearing which are abutted against and hooked by the connecting rod large end protrusion 5b. When the connecting rod 4 enters the compression stroke in a state where 1f is located on the cylinder side (not shown), that is, in the upward direction in FIG. 1, that is, with the short stroke set, the piston stroke becomes the shortest, that is, “ФD”, A compression ratio state is achieved.
[0051]
As described above, switching to the high compression ratio or the low compression ratio is performed.
[0052]
Next, the detailed configuration and operation of switching the compression ratio of the variable compression ratio mechanism of the internal combustion engine according to the first embodiment will be described with reference to FIG. 2 and FIG. 3 in addition to FIG. Here, FIGS. 4A and 4B are schematic sectional views in which the configurations of the crankshaft, the crankpin, the large end of the connecting rod, the eccentric bearing and the hydraulic piston according to the present embodiment are further enlarged.
[0053]
An inner diameter portion of the eccentric bearing 1 is externally fitted to a crankpin 3 of a crankshaft 2. On the other hand, the outer diameter portion of the eccentric bearing 1 is fitted inside the connecting rod large end base hole 5a. In addition, several eccentric bearing grooves 1a are provided on the side surface of the bush portion 1d constituting the eccentric bearing 1. An eccentric bearing hydraulic chamber 1b is provided in the eccentric bearing groove 1a on the center side, not the side surface side of the bush portion 1d.
[0054]
The control plate 6 is provided as a flange portion of the bush portion 1d, and switches the compression ratio as a component of the eccentric bearing 1. Specifically, since the control plate projection 6a provided on the control plate 6 is fitted into the eccentric bearing groove 1a, the control plate 6 can rotate integrally with the eccentric bearing 1. In addition, the control plate 6 is sandwiched between the opposing surface on the connecting rod large end portion 5 side and the opposing surface on the crankshaft 2 side. 2 and the horizontal direction in FIG. 4). The control plate 6 is provided with control plate lock portions 6b and 6c that can fix the position of the eccentric bearing 1. As will be described later, only the crankshaft protrusion 2c corresponding to the control plate lock 6c can abut on the control plate lock 6c, and the control rod lock end 6c does not hit the unsupported connecting rod large end protrusion 5b. And a recess 6e (see FIG. 3B). Similarly, only the connecting rod large end protrusion 5b corresponding to the control plate lock 6b can abut against the control plate lock 6b, and the control rod lock 6b is recessed so as not to hit the uncorresponding crankshaft protrusion 2c. 6d is provided (see FIG. 3C).
[0055]
In particular, as shown in FIG. 3A, the eccentric bearing 1 and the control plate 6 are vertically divided into two parts in the structure. As a result, the eccentric bearing 1 and the control plate 6 can be externally fitted to the crankpin portion 3. However, these may not be divided as long as they can be inserted from the tip of the crankpin portion 3. The control plate 6 abuts on the crankshaft projection 2c and hooks the control plate lock 6c to the thickest portion of the bush portion 1d of the eccentric bearing 1, that is, the thickest portion 1e of the eccentric bearing 1e described above. Assembled to position.
[0056]
As described above, the bush portion 1d of the eccentric bearing 1 is not uniform in thickness, and the thinnest portion of the bush portion 1d, that is, the eccentric bearing thinnest portion 1f is the thickest eccentric bearing portion. It is located at a position rotated by 180 degrees in the circumferential direction from the portion 1e. Therefore, from the thinnest portion 1f of the eccentric bearing to the thickest portion 1e of the eccentric bearing, the thickness gradually increases as the circumferential direction advances, but from the thickest portion 1e of the eccentric bearing to the thinnest portion 1f of the eccentric bearing. At, it becomes gradually thinner as it moves in the circumferential direction.
[0057]
Inside the crankshaft 2, a crankshaft hydraulic passage 2a and a crankshaft hydraulic passage 2b communicating with the crankshaft hydraulic passage 2a are provided. A crankshaft hydraulic chamber 2d is provided at the end of the crankshaft hydraulic passage 2b, and a hydraulic piston 7 and a spring 8 are provided inside the crankshaft hydraulic chamber 2d. The spring 8 has a sufficient spring force to push the hydraulic piston 7 to the right side in FIGS.
[0058]
Outside the crankshaft 2, a crankshaft protrusion 2 c is provided at a position abutting the control plate lock portion 6 c at a position outside the crankpin portion 3 on a surface facing the control plate 6 on the side of the crankshaft 2. ing.
[0059]
Outside the connecting rod large end 5, a connecting rod large end projection 5 b is provided at a position abutting on the control plate lock portion 6 b on a surface facing the control rod 6 on the side of the connecting rod large end 5.
[0060]
In particular, the switching of the compression ratio is performed by adjusting the opening of a solenoid valve (not shown) under the control of an electronic control unit (ECU) (not shown). The pumping pressure is adjusted, and the oil pressure of the lubricating oil is adjusted. A high compression ratio state is realized by increasing the oil pressure of the lubricating oil under the control of the ECU. On the other hand, a low compression ratio state is realized by a decrease in the oil pressure of the lubricating oil under the control of the ECU. The timing of increasing or decreasing the oil pressure of the lubricating oil and the adjustment amount of the oil pressure are uniquely determined from acquisition from a map table created in advance or calculation by a predetermined function.
[0061]
More specifically, when the oil pressure of the lubricating oil is increased at an appropriate time near the bottom dead center under the control of the ECU, the lubricating oil is provided in the crankshaft hydraulic passage 2 a provided in the crankshaft 2 and the crankpin portion 3. The hydraulic pressure inside the eccentric bearing groove 1a communicated with the crank pin portion hydraulic passage 3a and the eccentric bearing hydraulic chamber 1b is increased. When the oil pressure inside the eccentric bearing groove 1a is increased, the oil pressure for pushing the control plate protrusion 6a inserted into the eccentric bearing groove 1a to the left in FIGS. 6 can move to the left.
[0062]
At the same time, the hydraulic pressure inside the crankshaft hydraulic chamber 2d communicated with the crankshaft hydraulic passages 2a and 2b is increased. When the hydraulic pressure inside the crankshaft hydraulic chamber 2d is increased, the hydraulic pressure that pushes the hydraulic piston 7 inserted into the crankshaft hydraulic chamber 2d to the left in FIG. 2 is increased, and this hydraulic pressure is increased by a spring. When the spring force exceeds 8, the hydraulic piston 7 can move smoothly to the left. Therefore, the urging force received from the hydraulic piston 7 by the control plate 6 is reduced, and the control plate 6 can move smoothly to the left in FIGS. 2 and 4.
[0063]
As described above, the control plate 6 receives the hydraulic pressure generated from the inside of the eccentric bearing groove 1a from the right side in FIGS. 2 and 4, and has the hydraulic piston 7 fitted into the crankshaft hydraulic chamber 2d from the left side. Receive power. Since the hydraulic pressure and the urging force act on the control plate 6 while maintaining a balance, the control plate 6 can move smoothly to the left.
[0064]
Finally, the control plate 6 is pressed against the facing surface on the crankshaft 2 side as shown in FIGS. 2 and 4A. Therefore, only the control plate lock portion 6c located at the thickest portion 1e of the eccentric bearing can be caused to abut against the crankshaft protrusion 2c and hooked. Rotated. Therefore, when the crankshaft protrusion 2c comes to the position of the top dead center together with the crankshaft 2, the control plate lock portion 6c and the thickest portion 1e of the eccentric bearing, which are abutted against the crankshaft protrusion 2c and caught, are long. When the connecting rod 4 enters the compression stroke in the stroke setting state, the piston stroke becomes the longest, and a high compression ratio state is realized.
[0065]
On the other hand, under the control of the ECU, when the oil pressure of the lubricating oil is reduced at an appropriate time near the bottom dead center, the crankshaft hydraulic passage 2a provided in the crankshaft 2 and the crankshaft provided in the crankpin portion 3 are provided. The hydraulic pressure inside the eccentric bearing groove 1a communicated with the pin portion hydraulic passage 3a and the eccentric bearing hydraulic chamber 1b decreases. When the oil pressure inside the eccentric bearing groove 1a decreases, the oil pressure for pushing the control plate projection 6a inserted into the eccentric bearing groove 1a to the left in FIGS. Can move to the right.
[0066]
At the same time, the hydraulic pressure inside the crankshaft hydraulic chamber 2d connected to the crankshaft hydraulic passages 2a and 2b decreases. When the oil pressure inside the crankshaft oil pressure chamber 2d decreases, the oil pressure that pushes the hydraulic piston 7 inserted into the crankshaft oil pressure chamber 2d leftward in FIGS. When the spring force becomes larger than this hydraulic pressure, the hydraulic piston 7 can move to the right smoothly. Therefore, the rightward biasing force received by the control plate 6 from the hydraulic piston 7 increases, and the control plate 6 can smoothly move to the right in FIGS. 2 and 4.
[0067]
As described above, since the hydraulic pressure and the urging force act on the control plate 6 while maintaining a balance, the control plate 6 can move smoothly to the right in FIGS. 2 and 4.
[0068]
Eventually, the control plate 6 is pressed against the opposing surface on the connecting rod large end 5 side as shown in FIG. 4B. Therefore, only the control plate lock portion 6b located at the thinnest portion 1f of the eccentric bearing can be abutted against the connecting rod large end projection 5b and hooked, and the relative rotation of the eccentric bearing 1 is stopped. Therefore, when the connecting rod large end protrusion 5b comes to the position of the top dead center together with the crankshaft 2, the control plate lock portion 6b and the thinnest portion of the eccentric bearing which are abutted against and hooked by the connecting rod large end protrusion 5b. When the connecting rod 4 enters the compression stroke while 1f is in the short stroke setting state, the piston stroke becomes the shortest, and the low compression ratio state is realized.
[0069]
As described above, according to the first embodiment, regardless of the rotational speed of the relative rotation of the eccentric bearing, for example, by adjusting the oil pressure of the lubricating oil under the control of the electronic control unit, the control plate lock portion 6b is Since the connecting rod large end protruding portion 5b is abutted and hooked, there is little or no possibility of occurrence of a problem of engagement and a problem of a conventional lock pin being obliquely displaced and inserted into the engagement hole. Therefore, the failure of switching the compression ratio can be almost or completely eliminated. Therefore, it is possible to increase the certainty of switching the compression ratio.
[0070]
Further, according to the first embodiment, even if the relative rotation of the eccentric bearing is stopped, the oil pressure of the lubricating oil is adjusted as described above, so that the control plate lock unit is rotated during at least one rotation of the crankshaft. The eccentric bearing 1 is forced to rotate together with the crankshaft 2 by causing the crankshaft 6c to abut on the crankshaft protrusion 2c and to be hooked, thereby making it possible to almost or completely eliminate the failure in switching the compression ratio. Therefore, it is possible to increase the certainty of switching the compression ratio.
[0071]
Further, according to the first embodiment, since the control plate lock portion 6c or 6b and the crankshaft protrusion 2c or the connecting rod large end protrusion 5b are hooked by abutment, problems of meshing and a conventional lock pin are reduced. There is little or no wear resulting from the problem of being inserted obliquely into the mating hole. Therefore, the durability of switching the compression ratio can be improved.
[0072]
As described above, according to the first embodiment, for example, the operation of a specific internal combustion engine such that the relative rotation of the eccentric bearing almost or completely stops or the relative rotation of the eccentric bearing is faster than the engine rotation Even in the state, it is possible to enhance the reliability and durability of switching the compression ratio.
[0073]
(2nd Embodiment)
Next, a detailed configuration and operation of switching the compression ratio of the variable compression ratio mechanism of the internal combustion engine according to the second embodiment will be described with reference to FIGS. FIG. 5 is a schematic cross-sectional view in which the configurations of the crankshaft, the crankpin, the large end of the connecting rod, the eccentric bearing, and the hydraulic piston according to the second embodiment are enlarged. In the description of the second embodiment with reference to FIG. 5, the same components as those in the first embodiment are denoted by the same reference numerals, and the description thereof will be omitted as appropriate.
[0074]
In FIG. 5, the second embodiment is based on the first embodiment, and in order to more reliably switch the compression ratio, the rotation direction and the rotation range of the eccentric bearing 1 are easily restricted to a specified range. The outer peripheral surface of the outer diameter portion of the eccentric bearing 1 internally fitted in the connecting rod large end portion 5 and the connecting rod large end base hole 5a of the connecting rod large end portion 5 in which the outer diameter portion of the eccentric bearing 1 is internally fitted. On the peripheral surface, a component is newly added. The definition of the “specified range” will be described later in detail. Other configurations and operations according to the second embodiment are the same as those of the first embodiment.
[0075]
The variable compression ratio mechanism of the internal combustion engine according to the second embodiment shown in FIG. 5 includes, in addition to the components of the first embodiment, an eccentric bearing half-moon hole 1c provided on the eccentric bearing 1, a connecting rod large end. It is provided with a connecting rod large end hole 5c provided in the inner peripheral surface of the base hole 5a, and a ball 9 and a spring 10 provided in the connecting rod large end hole 5c.
[0076]
Next, the detailed configuration and operation of switching the compression ratio of the variable compression ratio mechanism of the internal combustion engine according to the second embodiment will be described with reference to FIGS. 3 and 4 appropriately in addition to FIGS. 5 and 6. I do. FIG. 6 is a schematic cross-sectional view in which the configurations of the eccentric bearing half-moon hole, the connecting rod large-end hole, the ball, and the spring according to the second embodiment are enlarged. Note that this cross-sectional view is a cross-sectional view in a direction perpendicular to the rotation center line of the eccentric bearing 1.
[0077]
5 and 6, an eccentric bearing half-moon hole 1c is provided on the outer peripheral surface of the outer diameter portion of the eccentric bearing 1 fitted inside the connecting rod large end base hole 5a of the connecting rod large end portion 5. The length of the inner diameter of the eccentric bearing half-moon hole 1c is larger than the length of the outer diameter of the ball 9 described later. Further, the shape of the eccentric bearing half-moon hole 1c may be a hole of a shape close to an ellipse having a long diameter in the relative rotation direction of the eccentric bearing 1, and preferably the ball 9 is formed by a circumferential force applied from the eccentric bearing half-moon hole 1c. Is provided with a taper at a predetermined angle.
[0078]
The connecting rod large end hole 5c is provided on the inner peripheral surface of the connecting rod large end base hole 5a of the connecting rod large end 5 into which the outer diameter portion of the eccentric bearing 1 is fitted. A spring 10 and a ball 9 are provided inside the connecting rod large end hole 5c.
[0079]
As described above, in the present embodiment, an example of the “engaging hole” according to the present invention includes the eccentric bearing half-moon hole 1c, and an example of the “projecting portion” according to the present invention includes the connecting rod large end hole 5c and the spring. 10 and a ball 9. However, the “projecting portion” may be constituted by another elastic body and a hydraulic or electric valve.
[0080]
Specifically, these components are urged toward the eccentric bearing half-moon hole 1c by the spring force of a spring 10 provided inside the connecting rod large end hole 5c, and as a result, the ball 9 is The eccentric bearing fits in the half moon hole 1c and maintains that state. Therefore, the rotation direction and the rotation range of the rotation of the eccentric bearing 1 are easily restricted within the specified range. Here, the "specified range" is a rotation range of relative rotation of the eccentric bearing 1 determined by the shape of the eccentric bearing half-moon hole 1c. More specifically, the eccentric bearing 1 has a long diameter in the relative rotation direction. The state in which the ball 9 is fitted is maintained from one end side to the other end side inside the shaped eccentric bearing half-moon hole 1c, so that the rotation of the eccentric bearing 1 is easily restricted. The restraining force for restraining the rotation direction and the rotation range of the eccentric bearing 1 within the specified range is determined by using the spring force of the spring 10, the diameter of the ball 9, and the depth of the eccentric bearing half-moon hole 1c as parameters. The basic operations of the eccentric bearing half-moon hole 1c, the connecting rod large end hole 5c, the ball 9 and the spring 10 that generate this restraining force are interlocked with the rotating operation "AR1" of the eccentric bearing 1 shown in FIG. Thus, the ball 9 performs an operation “AR2” of sinking while urging the spring 10. However, this restraining force is set to a level that cannot be released by the rotational force generated by the relative rotation of the crankshaft 2 acting on the eccentric bearing 1 due to the rotational moment of inertia. In addition, the restraining force is set to a level that is released by the rotational force caused by the forced rotation of the crankshaft 2 when the crankshaft protrusion 2c is hooked on the control plate lock 6c. Such a binding force can be individually and specifically set by experiment, empirical, theoretical, simulation, or the like according to the actual device specifications. Therefore, the restriction of the eccentric bearing 1 in the rotation direction and the rotation range within the specified range can be released only by switching to the high compression ratio, that is, by forcibly rotating the eccentric bearing 1 together with the crankshaft projection 2c of the crankshaft 2. .
[0081]
The connecting rod large end protruding portion 5b is connected to the control plate lock portion 6b at one end side or the other end side within a specified range for restricting the rotation direction and the rotation range of the eccentric bearing 1 at the connecting rod large end portion 5. It is provided at a position where it is abutted and hooked.
[0082]
Since the second embodiment is configured as described above, the rotation direction and the rotation range of the eccentric bearing 1 are likely to be constrained within the specified range, so that the compression ratio can be switched more reliably.
[0083]
Specifically, in the first embodiment, when the compression ratio is switched from the low compression ratio to the high compression ratio, the control plate lock portion 6b is abutted against the connecting rod large end projection 5b, and is separated from the hooked state to control. Since the rotation direction and the rotation range of the eccentric bearing 1 are not restricted until the plate lock portion 6c is abutted against and hooked on the crankshaft protrusion 2c, for example, the eccentric bearing 1 and the control plate 6 are rotated more than the crankshaft 2 rotates. There is a possibility that it will continue to rotate earlier. Therefore, it takes time before the control plate lock portion 6c is abutted against the crankshaft protrusion 2c and is caught or caught, and is not caught. Therefore, it takes time to switch to the high compression ratio or the switch is performed. There is a possibility that it will not be possible. On the other hand, in the second embodiment, since the rotation direction and the rotation range of the eccentric bearing 1 are likely to be constrained within the specified range, the control plate lock portion 6c is moved while the crankshaft 2 makes at least one rotation. It is possible to make it abut against the part 2c and hook it. Therefore, since the eccentric bearing is forcibly rotated together with the crankshaft and the long stroke setting state is realized, the failure of switching the high compression ratio can be almost or completely eliminated.
[0084]
On the other hand, in the first embodiment, when the compression ratio is switched from the high compression ratio to the low compression ratio, the control plate lock portion 6c is abutted from the crankshaft protrusion 2c, separates from the hooked state, and the control plate lock portion 6b Since the rotation direction and the rotation range of the eccentric bearing 1 are not restricted until the eccentric bearing 1 is abutted against and hooked on the connecting rod large end projection 5b, for example, the rotation of the eccentric bearing 1 and the control plate 6 is almost or completely stopped. There are some possibilities. Therefore, since the control plate lock portion 6b is abutted against the connecting rod large end protruding portion 5b and takes a long time to be hooked or is not abutted and is not caught, it takes time to switch to a low compression ratio or a switch. There is a possibility that will not be done. On the other hand, in the second embodiment, since the rotation direction and the rotation range of the eccentric bearing 1 are easily constrained within the specified range, the eccentric bearing 1 is positioned at one end side or the other end side within the specified range. , It is easy to cause the control plate lock portion 6b to abut against the connecting rod large end projection 5b and hook it. Therefore, the relative rotation of the eccentric bearing 1 is stopped, and the short stroke setting state is realized, so that the failure of switching the low compression ratio can be almost or completely eliminated.
[0085]
As described above, in the second embodiment, it is possible to more reliably switch the compression ratio.
[0086]
In the present embodiment, the control plate 6 is moved using the oil pressure of the lubricating oil in order to switch the compression ratio, but the pressure of another fluid (liquid or gas) may be used. In the present embodiment, the control plate 6 is pressed against the opposing surface on the side of the crankshaft 2 to realize switching to a high compression ratio, while the control plate 6 is pressed against the opposing surface on the connecting rod large end 5 side. Thus, the switching to a low compression ratio is realized, but this may adopt a reverse configuration and operation in accordance with the characteristics required for the internal combustion engine. Further, in the present embodiment, the compression ratio can be switched between high and low by using the thickness of the bush portion 1d of the eccentric bearing 1. However, the compression ratio can be changed to three or more stages by using the thickness of the bush portion 1d. It may be configured to switch to.
[0087]
The present invention is not limited to the above-described embodiment, but can be appropriately changed within a scope not contrary to the gist or idea of the invention which can be read from the claims and the entire specification, and the variable of the internal combustion engine accompanying such changes The compression ratio mechanism is also included in the technical scope of the present invention.
[0088]
【The invention's effect】
As described above in detail, according to the present invention, for example, in a variable compression ratio mechanism of an internal combustion engine, it is possible to increase the reliability and durability of switching the compression ratio.
[Brief description of the drawings]
FIG. 1 is a schematic front view showing the operation of an eccentric bearing, a connecting rod large end, and a crankshaft according to the present embodiment.
FIG. 2 is an enlarged schematic cross-sectional view of a configuration of a crankshaft, a crankpin, a large end of a connecting rod, an eccentric bearing, and a hydraulic piston according to the first embodiment.
3 is a schematic exploded perspective view of the eccentric bearing according to the embodiment (FIG. 3A) and a schematic perspective view in which a control plate lock portion of the eccentric bearing is enlarged (FIGS. 3B and 3C). It is.
FIG. 4 is a schematic cross-sectional view in which the configurations of a crankshaft, a crankpin, a large end of a connecting rod, an eccentric bearing, and a hydraulic piston according to the present embodiment are further enlarged. However, FIG. 4A shows a case where the hydraulic pressure is increased, and FIG. 4B shows a case where the hydraulic pressure is reduced.
FIG. 5 is a schematic cross-sectional view enlarging a configuration of a crankshaft, a crankpin, a large end of a connecting rod, an eccentric bearing, and a hydraulic piston according to a second embodiment.
FIG. 6 is a schematic cross-sectional view enlarging a configuration of an eccentric bearing half-moon hole, a connecting rod large end hole, a ball, and a spring according to a second embodiment.
[Explanation of symbols]
1 Eccentric bearing
1a Eccentric bearing groove
1b Eccentric bearing hydraulic chamber
1c Eccentric bearing half moon hole
1d bush part
1e Thickest part of eccentric bearing
1f Thinnest part of eccentric bearing
2 Crankshaft
2a Crankshaft hydraulic passage
2b Crankshaft hydraulic passage
2c Crankshaft protrusion
2d crankshaft hydraulic chamber
3 Crank pin part
3a Crank pin section hydraulic passage
4 Connecting rod (connecting rod)
5 Connecting rod large end
5a Connecting rod large end base hole
5b Connecting rod large end projection
5c Connecting rod large end hole
6 Control plate
6a Control plate protrusion
6b Control plate lock
6c Control plate lock
6d control plate recess
6e Control plate recess
7 Hydraulic piston
8 Spring
9 ball
10 Spring

Claims (6)

(I) a bush portion in which an outer diameter portion fitted inside the large end of the connecting rod and an inner diameter portion fitted outside the crankpin are eccentric to each other; (ii) reciprocation along the rotation center line direction of the bush portion A control plate which is movable and is rotatable integrally with the bush portion as a flange portion of the bush portion, (iii) provided on the control plate, wherein the control plate is provided together with the bush portion together with the connecting rod. A first lock portion for fixing the internal combustion engine at a first circumferential position for a first compression ratio with respect to the large end portion and the crankshaft; and (iv) the control plate is provided on the control plate. An eccentric bearing having, together with the bush portion, a second lock portion for fixing the plate at a second circumferential position for a second compression ratio different from the first compression ratio;
The eccentric bearing is provided on a surface of the crankshaft facing the control plate, and when the control plate moves to a side away from the bush portion, the eccentric bearing is forcibly rotated together with the crankshaft via the control plate. A first protrusion that is caught on the first lock portion,
The eccentric bearing is provided on a surface facing the control plate at the large end of the connecting rod, and when the control plate moves to a side approaching the bush portion, the eccentric bearing is connected to the large end of the connecting rod via the control plate. A second protruding portion hooked to the second lock portion so as to be fixed to the second lock portion. The first lock portion is provided at a position or shape where the second protrusion is not caught when the control plate moves to a side approaching the bush portion,
The said 2nd lock part is provided in the position or shape which the said 1st protrusion part does not catch, when the said control plate moves to the side away from the said bush part, The said 2nd lock part is characterized by the above-mentioned. Variable compression ratio mechanism for internal combustion engines. The control plate is provided on at least one of the connecting rod large end and the crankshaft, and when the oil pressure of the lubricating oil is higher than a set value, the control plate is moved to a side away from the bush portion by the oil pressure. 3. The variable compression ratio mechanism for an internal combustion engine according to claim 1, further comprising a drive unit that moves the control plate to a side closer to the bush when the pressure is lower than a set value. The first lock portion is provided on the opposite side of the rotation center line of the inner diameter portion with respect to the rotation center line of the outer diameter portion, and the second lock portion is provided on the first lock portion with the rotation center line. The first circumferential position is provided for a high compression ratio, and the second circumferential position is provided for a low compression ratio. A variable compression mechanism for an internal combustion engine according to any one of the preceding claims. The connecting rod further includes a protruding portion that can protrude in a radial direction of the outer diameter portion on an inner peripheral surface of the large end portion that is fitted to the outer diameter portion,
The variable compression ratio mechanism for an internal combustion engine according to any one of claims 1 to 4, wherein the outer diameter portion includes a wall portion that defines an engagement hole with which the protrusion can be engaged. The protrusion is
A spring that is disposed inside another hole formed in the inner peripheral surface of the connecting rod large end and is expandable and contractable in the radial direction.
6. The variable compression ratio mechanism for an internal combustion engine according to claim 5, further comprising a ball disposed at a tip end side of the spring and urged to the outside of the other hole by the spring.

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