JP4120511B2 - Variable compression ratio mechanism for internal combustion engine and top dead center position adjusting method thereof - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a variable compression ratio mechanism for an internal combustion engine, and more particularly to a technique that enables fine adjustment of the compression ratio (piston top dead center position) of each cylinder in a multi-cylinder internal combustion engine.
[0002]
[Prior art]
In an internal combustion engine with a supercharger, the supercharger is operated at a high load that requires output. At the time of supercharging, the amount of intake air and the pressure increase, so that knocking is likely to occur. Therefore, knocking is prevented by lowering the compression ratio during high load operation with supercharging intake air, and good fuel efficiency is ensured by increasing the compression ratio during low and medium load operation without supercharging intake air. A technique relating to an internal combustion engine (a multi-link piston stroke mechanism) intended to do this is disclosed (for example, see Patent Document 1).
[0003]
In this multi-link type piston stroke mechanism, a piston pin and a crank pin are connected via a multi-link composed of an upper link and a lower link, and a control link is connected to the lower link. Then, the variable compression ratio mechanism is realized by controlling the top dead center position of the piston by changing the inclination of the lower link by controlling the control link in accordance with the operating state.
[0004]
[Patent Document 1]
JP-A-2001-342859 gazette
[Problems to be solved by the invention]
By the way, since the multi-link type piston stroke mechanism (variable compression ratio mechanism) as described above has a large number of parts and a complicated structure, the engine compression ratio (piston top dead center position) may vary between cylinders. . If there is such variation, the combustion pressure between the cylinders becomes non-uniform and smooth operation cannot be performed. In addition, performance varies from engine to engine and the quality is not stable.
[0006]
The present invention has been made paying attention to such a conventional problem, and in the multi-link type piston stroke mechanism, the compression ratio (piston top dead center position) between the cylinders without incurring a great cost. It is an object of the present invention to provide a variable compression ratio mechanism for an internal combustion engine that can reduce the variation of the internal combustion engine.
[0007]
[Means for Solving the Problems]
The present invention solves the above problems by the following means. In addition, in order to make an understanding easy, although the code | symbol corresponding to embodiment of this invention is attached | subjected, it is not limited to this.
[0008]
In the multi-cylinder internal combustion engine having a piston that reciprocates in a cylinder, the present invention rotates to a first link (11) connected to the piston via a first connection pin and a crank pin (21b) of a crankshaft. A second link (12) that is freely mounted and connected to the first link via a second connecting pin (25), and is connected to the second link via a third connecting pin (26). A third link (13) and an eccentric shaft portion (14a) that is rotatably supported by the cylinder block and eccentric with respect to the rotation shaft, and the third link is detachably connected to the eccentric shaft portion. , a variable compression ratio mechanism for an internal combustion engine and a control shaft (14) for variably controlling the engine compression ratio by rotating in accordance with the engine operating conditions to adjust the position of the third link, Shirindabu Is formed on the click of the bulk wall (33), the Rukoto includes a hole for the removable (34) the third connecting pin (26) from the slide moves in the axial direction the third link (13) Features.
[0009]
[Action / Effect]
According to the present invention, after assembling all the links (that is, after weaving all the component variations), it is possible to remove only the third link and adjust the piston top dead center position. The position can be accurately obtained.
[0010]
If the piston position is adjusted by changing the size of the third link in this way, the piston crown at the piston bottom dead center is approximately the same and in the same direction when the piston crown position at the piston top dead center changes. Since the surface position also changes, the displacement of each cylinder (that is, the difference between the piston crown surface position at the piston top dead center and the piston crown surface position at the piston bottom dead center multiplied by the cylinder cross-sectional area) The compression ratio of each cylinder can be adjusted without greatly changing.
[0011]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be described in more detail with reference to the drawings. (First embodiment)
The internal combustion engine of the variable compression ratio mechanism of the present invention is, for example, an in-line 4-cylinder spark ignition gasoline engine. FIG. 1 is a cross-sectional view showing the link state (top dead center) of the variable compression ratio mechanism during high compression ratio control, and FIG. It is sectional drawing which shows a dead point. First, the structure and operation of the variable compression ratio mechanism will be described with reference to these drawings.
[0012]
The crankshaft 21 includes a plurality of journals 21a and a crankpin 21b. The journal 21a is rotatably supported by a hole 33a (see FIG. 4) formed in a bulk wall 33 that partitions the inside of the cylinder block 31. The crank pin 21b is eccentric by a predetermined amount from the journal 21a, and a lower link (second link) 12 is rotatably connected thereto. The lower link 12 has a crank pin 21b inserted in a substantially central connecting hole and rotates around the crank pin 21b as a central axis. The lower link 12 is configured to be divided into two members on the left and right. The lower link 12 connects an upper link (first link) 11 at one end and a control link (third link) 13 at the other end.
[0013]
The upper link 11 has a lower end side rotatably connected to one end of the lower link 12 by a connecting pin 25, and an upper end side rotatably connected to the piston 22 by a piston pin 24. The piston 22 receives the combustion pressure and reciprocates in the cylinder 31 a of the cylinder block 31.
[0014]
The control link 13 has a two-body structure including a rod portion 13a and a cap portion 13b. A connecting pin 26 is inserted into the boss portion at the tip of the rod portion 13 a and is rotatably connected to the lower link 12. Further, the control shaft 14 is inserted into the contact surface portions of the rod portion 13a and the cap portion 13b, and the control shaft 14 swings as indicated by the arrow in FIG. The control link 13 is prepared with different distances from the center of the hole for inserting the connecting pin 26 to the center of the hole for inserting the control shaft 14 (hereinafter referred to as “the distance between the bearing holes”). In consideration of parts management, cost, etc., it is preferable to prepare a graded bearing hole with different distances in stages.
[0015]
The control shaft 14 has four eccentric shaft portions 14a, and the control links 13 of the four cylinders are connected to the eccentric shaft portions 14a, respectively (see FIG. 3). The control shaft 14 is rotatably supported by a lower portion of a bulk wall 33 that partitions the inside of the cylinder block 31. The control shaft 14 is rotated by, for example, the actuator 5. The compression ratio can be changed by rotating the control shaft 14. Details will be described below.
[0016]
FIG. 3 is a side view showing a configuration in the vicinity of a control shaft, a control link, and a crankshaft.
[0017]
As shown in FIG. 3, the control shaft 14 is disposed in parallel with the crankshaft 21 along the cylinder row direction. The control shaft 14 has four eccentric shaft portions 14a, and the control links 13 of the four cylinders are connected to the eccentric shaft portions 14a, respectively.
[0018]
And the actuator 5 is coaxially attached in the edge part of an engine longitudinal direction. The actuator 5 is controlled by a controller (not shown). The controller determines a target compression ratio based on engine operating conditions such as engine rotation speed, load, intake negative pressure, and exhaust temperature, and controls the actuator 5 so that the compression ratio can be realized. When the actuator 5 rotates the control shaft 14, the eccentric shaft portion 14a moves and the swing center of the control link 13 moves, so that the compression ratio of the variable compression ratio mechanism 1 can be controlled. For example, as shown in FIG. 1, when the compression ratio is controlled to a high compression ratio, the control shaft 13 is rotated and the control link 13 is pulled downward by the eccentric shaft portion 14a. Then, the lower link 12 moves clockwise and the connecting pin 25 is pushed up, so that the position of the piston 22 at the piston top dead center (TDC) is raised. In this way, the compression ratio is controlled to a high compression ratio. As shown in FIG. 2, when the compression ratio is controlled to a low compression ratio, the control shaft 14 is rotated and the control link 13 is pushed upward by the eccentric shaft portion 14a. Then, the lower link 12 moves counterclockwise and the connecting pin 25 is pulled down, so that the position of the piston 22 at the piston top dead center (TDC) is lowered. In this way, the compression ratio is controlled to a low compression ratio.
[0019]
1 and 2 representatively show a high compression ratio state and a low compression ratio state, but the compression ratio can be continuously changed between them.
[0020]
FIG. 4 is a view showing a bulk wall in the cylinder block.
[0021]
The bulk wall 33 is formed in the cylinder block 31 and the ladder frame 32, and divides the crankcase of the internal combustion engine for each cylinder. A hole 33a is formed in the bulk wall 33, and the crank journal 21a of the crankshaft 21 is rotatably supported by the hole 33a.
[0022]
In addition, a hole 34 is formed in the bulk wall 33. The hole 34 is formed on the movement locus (arrow in FIG. 4) of the connecting pin 26 when the control shaft 14 is in the maximum compression ratio state (state in FIG. 1). The size of the hole 34 is a size through which the connecting pin 26 can pass.
[0023]
FIG. 5 is an enlarged cross-sectional view of the periphery of a connecting pin that connects the control link and the lower link.
[0024]
As described above, the hole 34 is formed in the bulk wall 33. The connecting pin 26 is inserted into the lower link 12 and the control link 13 and connects the lower link 12 and the control link 13 so as to be swingable. At both ends of the connecting pin 26, for example, a drop prevention member 27 such as an E-ring is attached.
[0025]
When the drop prevention member 27 is removed, the connecting pin 26 can move in the axial direction (the arrow direction in FIG. 5). Therefore, after removing the drop prevention member 27, the connecting pin 26 can be temporarily inserted into the hole 34 of the bulk wall 33 and removed, and if the connecting pin 26 is removed, the control link 13 is removed from the lower link 12. Can do.
[0026]
(Piston top dead center position adjustment method)
A reference control link 13A having a reference bearing hole distance is assembled to the internal combustion engine body together with the piston 22, the upper link 11, the lower link 12, the control shaft 14, and the crankshaft 21 (reference link assembling step).
[0027]
Next, the control shaft 14 is rotated to the maximum compression ratio (control shaft rotating step).
[0028]
Subsequently, the piston crown surface position at the top dead center of the piston is measured (top dead center position measuring step), an error from the design value is obtained, and a distance between the bearing holes that can eliminate the error is obtained.
[0029]
And it reassembles to the control link 13 for this assembly | attachment which has the distance between the bearing holes (link reorganization process). As a specific replacement operation, first, the connecting pin 26 is slid and pulled out from the reference control link 13A in the axial direction, and the cap portion 13b of the control link 13 is removed. Subsequently, the control link 13 is removed from the control shaft 14. Then, the reference control link 13A is rearranged to the main assembly control link 13. Next, the assembled control link 13 is assembled to the control shaft 14, the through holes of the assembled control link 13 and the lower link 12 are aligned, the connecting pin 26 is inserted, and the drop prevention members are inserted at both ends of the connecting pin 26. 27 is attached.
[0030]
By doing in this way, the control link 13 can be rearranged without removing the piston 22, the upper link 11, the lower link 12, the control shaft 14, and the crankshaft 21.
[0031]
According to this embodiment, the control link 13 is connected to the lower link 12 by the connecting pin 26. And since the hole 34 was provided in the bulk wall 33 so that the connecting pin 26 can move largely in the axial direction, the connecting pin 26 is slid and removed from the control link 13 even after all the links are once assembled. The control link 13 can be removed.
[0032]
Thus, after assembling all the links (that is, after weaving all the component variations), it is possible to remove only the control link 13 and adjust the piston crown position at the top dead center of the piston. Therefore, the position can be accurately obtained.
[0033]
If the piston crown position is adjusted as described above, the displacement of each cylinder (that is, the difference between the piston crown position at the top dead center of the piston and the piston crown position at the bottom dead center of the cylinder) The compression ratio of each cylinder can be adjusted without greatly changing the product of the cross-sectional area. That is, if the distance between the bearing holes of the control link 13 is changed to change the piston crown surface position at the top dead center of the piston, the piston crown surface position at the bottom dead center of the piston also changes in substantially the same direction. This is because the displacement does not change.
[0034]
Further, if the distance between the center of the crank pin 21b and the center of the connection pin 26 is made longer than the distance between the center of the crank pin 21b and the center of the connection pin 25, the piston than the change in the distance between the bearing holes of the control link 13 is achieved. The change in the piston crown position at the top dead center is reduced. Therefore, the piston crown surface position can be adjusted with higher accuracy.
[0035]
Furthermore, if the distance between the bearing holes of the control link 13 is set for each stage, the piston position at the top dead center of the piston in each cylinder and each engine is within a predetermined range with a variation in the allowable compression ratio without increasing the number of parts. Can fit inside.
[0036]
(Second Embodiment)
FIG. 6 is a view showing a second embodiment of the control link of the variable compression ratio mechanism of the internal combustion engine according to the present invention.
[0037]
In the following embodiments, portions that perform the same functions as those of the first embodiment described above are denoted by the same reference numerals, and redundant descriptions are omitted as appropriate.
[0038]
A bearing bush 15 is fitted in the upper bearing hole of the control link 13, and a bearing bush 16 is fitted in the lower bearing hole. By exchanging these bearing bushes, the distance between the bearing holes of the control link 13 can be adjusted. The top dead center position of the piston is adjusted by appropriately adjusting the distance between the bearing holes of the control link 13.
[0039]
For example, first, as the reference control link 13A, a link having a distance between the bearing holes having the same length as that when a bearing bush having no eccentricity (the bearing bush 15b and the bearing bush 16b in this embodiment) is fitted into the control link 13 is used. use.
[0040]
And when this reference | standard control link 13A is assembled | attached, if the position of a piston crown surface is higher than a design position, it will change to the control link with which the eccentric bearing bush 15a and the bearing bush 16a were fitted. In this way, since the distance between the bearing holes is extended, the lower link 12 rotates counterclockwise, the upper link 11 pulls the piston pin 1 downward, and the piston crown surface descends.
[0041]
Further, when the reference control link 13A is assembled, if the position of the piston crown surface is lower than the design position, the reference control link 13A is replaced with a control link in which the eccentric bearing bush 15c or bearing bush 16c is fitted. By doing so, the distance between the bearing holes is shortened, so that the lower link 12 rotates clockwise, and the upper link 11 pushes the piston pin 1 upward, so that the piston crown surface rises.
[0042]
Further, when the reference control link 13A is assembled, if the position of the piston crown surface is as designed, the control link is reassembled with the bearing bush 15b and the bearing bush 16b fitted.
[0043]
The eccentric amount of the eccentric bearing bush may be different from each other. Multiplier of the bearing bush (upper three types 15a, 15b, 15c in the present embodiment) of the control link 13 and the lower bearing bush (three types 16a, 16b, 16c in the present embodiment) This is because in the embodiment, control links of 9 types of 3 × 3 grades) can be prepared.
[0044]
According to this embodiment, since the bearing bushes 15 and 16 are fitted into the control link 13 and the distance between the bearing holes is changed depending on the amount of eccentricity of the bearing bushes 15 and 16, the control links having different distances between the bearing holes are provided. It can be manufactured at low cost.
[0045]
Further, if the eccentric amounts of the eccentric bearing bushes are different from each other, control links corresponding to multipliers between the number of types of the bearing bush 15 and the number of types of the bearing bush 16 can be prepared.
[0046]
(Third embodiment)
FIG. 7 is a view showing a third embodiment of the variable compression ratio mechanism of the internal combustion engine according to the present invention.
[0047]
The bearing boss of the control link 13 into which the connecting pin 26 is inserted has a two-body structure of a rod portion 13a and a cap portion 13c, and the rod portion 13a and the cap portion 13c are fixed with a fastening member 13d such as a bolt. If the fastening member 13d is loosened, the cap portion 13c can be detached from the rod portion 13a and only the control link 13 can be removed.
[0048]
According to the present embodiment, only the control link 13 can be removed by loosening the fastening member 13d and removing the cap portion 13c from the rod portion 13a without forming the hole 34 in the first embodiment. . Therefore, even in the present embodiment, the compression ratio of each cylinder can be adjusted by changing the distance between the bearing holes of the control link 13 as in the above embodiment.
[0049]
The present invention is not limited to the embodiment described above, and various modifications and changes can be made within the scope of the technical idea, and it is obvious that these are equivalent to the present invention.
[0050]
For example, in each of the above embodiments, the case where the crankshaft 21 is supported by the cylinder block 31 by the ladder frame 32 has been described as an example. However, as shown in FIGS. Instead, the same applies to the case where the cylinder block 31 is supported by the main bearing cap 36. Also in this case, the bulk wall 33 has a hole 34 of a size through which the connecting pin 26 can pass on the movement locus (arrow in FIG. 9) of the connecting pin 26 when the control shaft 14 is in the maximum compression ratio state. Form it. Even if it is such a form, the effect similar to the said embodiment can be acquired.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing a link state (top dead center) during high compression ratio control of a variable compression ratio mechanism of an internal combustion engine according to the present invention.
FIG. 2 is a cross-sectional view showing a link state (top dead center) at the time of low compression ratio control of the variable compression ratio mechanism of the internal combustion engine according to the present invention. FIG.
FIG. 4 is a diagram showing a bulk wall in a cylinder block.
FIG. 5 is an enlarged cross-sectional view of the periphery of a connecting pin that connects a control link and a lower link.
FIG. 6 is a view showing a second embodiment of the control link of the variable compression ratio mechanism of the internal combustion engine according to the present invention.
FIG. 7 is a view showing a third embodiment of a variable compression ratio mechanism for an internal combustion engine according to the present invention.
FIG. 8 is a diagram showing a case where a crankshaft is supported on a cylinder block by a main bearing cap.
FIG. 9 is a diagram showing a cylinder block in that case.
[Explanation of symbols]
1 Variable compression ratio mechanism 11 Upper link (first link)
12 Lower link (second link)
13 Control link (3rd link)
13a Rod portion 13b, 13c Cap portion 14 Control shaft 14a Eccentric shaft portion 15, 16 Bearing bush 20 Cylinder block 21 Crank shaft 21a Journal 21b Crank pin 22 Piston 23 Cylinder 24 Piston pin (first connecting pin)
25 connecting pin (second connecting pin)
26 connecting pin (third connecting pin)
31 Cylinder block 32 Ladder frame 33 Bulk wall 33a, 34 Hole 36 Main bearing cap

Claims (8)

In a multi-cylinder internal combustion engine having a piston that reciprocates in a cylinder,
A first link coupled to the piston via a first coupling pin;
A second link that is rotatably mounted on a crankpin of the crankshaft and connected to the first link via a second connecting pin;
A third link coupled to the second link via a third coupling pin;
An eccentric shaft portion that is rotatably supported by the cylinder block and is eccentric with respect to the rotation shaft is detachably connected to the eccentric shaft portion, and is rotated according to the engine operating state to rotate the first link. A control shaft that variably controls the engine compression ratio by adjusting the position of the three links;
A variable compression ratio mechanism for an internal combustion engine comprising:
A hole formed on a bulk wall of the cylinder block, the third connecting pin being slidable in an axial direction to be removable from the third link;
A variable compression ratio mechanism for an internal combustion engine. The hole is formed on the movement locus of the third connecting pin when the control shaft is rotated and the link arrangement is in the engine maximum compression ratio state.
The variable compression ratio mechanism for an internal combustion engine according to claim 1. In a multi-cylinder internal combustion engine having a piston that reciprocates in a cylinder,
A first link coupled to the piston via a first coupling pin;
A second link that is rotatably mounted on a crankpin of the crankshaft and connected to the first link via a second connecting pin;
A third link coupled to the second link via a third coupling pin;
An eccentric shaft portion that is rotatably supported by the cylinder block and is eccentric with respect to the rotation shaft is detachably connected to the eccentric shaft portion, and is rotated according to the engine operating state to rotate the first link. A control shaft that variably controls the engine compression ratio by adjusting the position of the three links;
A variable compression ratio mechanism for an internal combustion engine comprising:
The third link includes a cap part and a rod part formed so as to be separable across the third connecting pin, and is formed so that only the third link can be removed by removing the cap part from the rod part.
Variable compression ratio mechanism of the internal combustion engine you wherein a. Third connecting pin before Symbol comprises desorption free抜落preventing means,
The variable compression ratio mechanism for an internal combustion engine according to any one of claims 1 to 3 , wherein the variable compression ratio mechanism is provided. The distance between the crank pin and the third connecting pin is longer than the distance between the crank pin and the second connecting pin.
The variable compression ratio mechanism for an internal combustion engine according to any one of claims 1 to 4, wherein the variable compression ratio mechanism is provided. A reference link assembling step of assembling a third link having a reference length in which the distance between the eccentric shaft portion of the control shaft and the third connecting pin is formed as a reference length;
A control shaft rotation step for rotating the control shaft to bring the link arrangement to the engine maximum compression ratio state;
A top dead center position measuring step for measuring a piston top dead center position;
When the piston top dead center position is deviated from the reference position, by removing the third connecting pin through the hole formed in the bulk wall, without removing the first link and the second link, It has been reclassified the third link, the third link reclassification process you adjust the piston top dead point position as a reference position,
The top dead center position adjusting method for adjusting the top dead center position of the variable compression ratio mechanism of the internal combustion engine according to claim 2 . A reference link assembling step of assembling a third link having a reference length in which the distance between the eccentric shaft portion of the control shaft and the third connecting pin is formed as a reference length;
A top dead center position measuring step for measuring a piston top dead center position;
When the piston top dead center position deviates from the reference position, the cap portion of the third link is separated, and the third link is rearranged without removing the first link and the second link. A third link reassigning step of adjusting the point position to the reference position;
The top dead center position adjusting method for adjusting the top dead center position of the variable compression ratio mechanism of the internal combustion engine according to claim 3 . Adjusting the distance between the eccentric shaft portion of the control shaft of the third link and the third connecting pin by an eccentric bush;
The top dead center position adjusting method according to claim 6 or 7 , wherein the variable compression ratio mechanism of the internal combustion engine is set.

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