JP7112905B2 - Multi-link piston crank mechanism - Google Patents

Description

The present invention relates to a piston crank mechanism for an internal combustion engine, and more particularly to a multi-link piston crank mechanism.

An example of the multi-link type piston crank mechanism is disclosed in Patent Document 1. This multi-link type piston crank mechanism includes an upper link, one end of which is connected to a piston via a piston pin, and a lower link, which is connected to the other end of the upper link via an upper pin and is connected to a crankpin of a crankshaft. It has a link and a control link that regulates the degree of freedom of this lower link. The lower link has a parallelogram shape that is similar to a rhombus, and an upper pin fitting hole and a control pin fitting hole are formed on both sides of a crank pin bearing provided in the center of the lower link. Such a lower link has a structure in which the center of gravity of the lower link is positioned at the center of the crankpin bearing portion.

In the multi-link piston crank mechanism, the force from the upper link that moves up and down due to the combustion pressure from the piston is input to the lower link, and the lower link swings about the control pin.

JP 2017-53416 A

In the multi-link type piston crank mechanism of Patent Document 1, a vertical vibration component is generated due to the vertical movement of the piston and the upper link. In an odd-numbered cylinder internal combustion engine, such as a three-cylinder internal combustion engine, this vibration component is not canceled and still remains. The vibration component causes yaw vibration and pitch vibration in the internal combustion engine, which may deteriorate the sound vibration performance of the internal combustion engine.

Furthermore, there is a risk that the noise and vibration performance of the internal combustion engine will further deteriorate due to the extension of the stroke of the multi-link type piston crank mechanism for the purpose of improving fuel efficiency.

In the present invention, the light weight portion made of a material having a relatively small specific gravity is provided in the hole provided in the bottom portion of the groove on the upper pin fitting hole side of the lower link.

Therefore, the center of gravity of the lower link including the light weight portion is located near the control pin fitting hole. This suppresses the generation of vibration components associated with the vertical motion of the upper link.

According to the present invention, yaw vibration and pitch vibration occurring in the internal combustion engine are reduced, thereby improving the noise and vibration performance of the internal combustion engine.

FIG. 2 is a configuration explanatory diagram of the multi-link type piston crank mechanism of the first embodiment; FIG. 4 is a perspective view of the lower link of the first embodiment; FIG. 4 is a plan view of the lower link of the first embodiment; 7A and 7B are graphs showing changes in the amplitude of yaw vibration when a lower link having a basic shape is used and when the lower link of the first embodiment is used; Shows the magnitude of yaw vibration and pitch vibration when using a lower link having a basic shape, when using the lower link of the first embodiment, and when using the lower link of the second embodiment. It is an explanatory diagram. FIG. 11 is a plan view of the lower link of the second embodiment; FIG. 11 is a plan view of a lower link of the third embodiment; It is a perspective view of the lower link upper of a 3rd Example. FIG. 11 is a plan view of a lower link of a fourth embodiment;

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 shows a multi-link piston crank mechanism of a first embodiment applied to each cylinder of an odd-numbered cylinder internal combustion engine, for example, an in-line three-cylinder internal combustion engine. This multi-link type piston crank mechanism includes an upper link 3, one end of which is connected to a piston 1 via a piston pin 2, and the other end of the upper link 3, which is connected to the other end of the upper link 3 via an upper pin (connection pin) 4. A lower link 6 connected to a crankpin 5 of a shaft and a control link 7 for restricting the degree of freedom of the lower link 6 are provided. One end of the control link 7 is swingably supported by a support pin 8 on the engine body side, and the other end is connected to the lower link 6 via a control pin (connection pin) 9 . The multi-link piston crank mechanism can also be configured as a variable compression ratio mechanism by making the position of the support pin 8 variable.

The lower link 6 has a basic shape configured to ensure the required rigidity as a single piece of the lower link 6 and to minimize the weight of the lower link 6. It is formed in a shape in which a weight portion 10 projecting from the top is added. The lower link 6 is made of a metal material such as SCR420H. Here, the specific gravity of SCR420H is 7.8.

The basic shape of the lower link 6 is, as shown in FIGS. 2 and 3, a parallelogram that is close to a rhombus surrounded by solid and broken lines. As shown in FIGS. 2 and 3, this basic shape includes a pair of first linear portions 14 and 15 extending in parallel from two vertices 12 and 13 facing each other with a central crankpin bearing portion 11 interposed therebetween; A pair of second straight portions 16, 17 extending in parallel from the vertices 12, 13 so as to form a predetermined inclination angle α with the first straight portions 14, 15 and opposite to the vertices 12, 13 On the side, two arc portions 18 and 19 connecting the first straight portion 14 and the second straight portion 16 and the first straight portion 15 and the second straight portion 17 are formed. A portion of the first linear portion 14, a portion of the circular arc portion 18, and a portion of the second linear portion 16 form a pair of upper pin pin boss portions 20a, 20a facing each other on both axial end sides of the crankpin 5. Configure. On the other hand, a portion of the first linear portion 15, a portion of the circular arc portion 19 and a portion of the second linear portion 17 are arranged on both axial end sides of the crankpin 5 so as to form a pair of control pin pin boss portions 21a, 21a facing each other. (only one is shown in FIG. 2). The upper pin pin boss portions 20a, 20a and the control pin pin boss portions 21a, 21a are located on opposite sides of each other with the crank pin bearing portion 11 located in the center of the lower link 6 therebetween.

A circular upper pin fitting hole 22 having a diameter smaller than that of the crank pin bearing portion 11 and into which the upper pin 4 is fitted is formed in the upper pin pin boss portion 20a. Here, the arc portion 18 is concentric with the upper pin fitting hole 22 .

On the other hand, the control pin pin boss portion 21a is formed with a circular control pin fitting hole 23 having a diameter smaller than that of the crankpin bearing portion 11 and into which the control pin 9 is fitted. Here, the arc portion 19 is concentric with the control pin fitting hole 23 .

The center of gravity G<b>1 of the basic shape of the lower link 6 configured in this way is positioned near the center C<b>1 of the crankpin bearing portion 11 .

2 and 3, the lower link 6 includes a lower link upper 6A including upper pin pin boss portions 20a, 20a and a control pin pin boss portion 20a on a dividing plane 24 passing through the center C1 of the crankpin bearing portion 11. A lower link lower 6B including pin boss portions 21a, 21a is formed by being divided into two parts.

The lower link upper 6A and the lower link lower 6B are fastened together by two bolts 25 (see FIG. 3) after the crankpin bearing portion 11 is fitted onto the crankpin 5. As shown in FIG. When the lower link upper 6A and the lower link lower 6B are fastened to each other in this manner, the lower link 6 has two end faces 27, 27 (see FIGS. 2 and 3) along a plane orthogonal to the upper pin 4 and the control pin 9. (only one shown).

A groove portion 28 recessed in the axial direction of the crankpin 5 is formed at a portion of the lower link upper 6A between the first straight portion 14 and the crankpin bearing portion 11 of each end surface 27 for weight reduction. ing. The groove portion 28 has a substantially rectangular shape when viewed from the axial direction of the crankpin 5 and is continuous from the vicinity of the upper pin fitting hole 22 to the vicinity of the vertex 12 .

Similarly, a groove portion 29 recessed in the axial direction of the crankpin 5 is formed at a portion of the lower link lower portion 6B on the opposite side of the groove portion 28 with respect to the crankpin bearing portion 11 in each end face 27 for weight reduction. there is The groove portion 29 has a substantially rectangular shape when viewed from the axial direction of the crankpin 5 and continues from the vicinity of the control pin fitting hole 23 to the vicinity of the vertex 13 .

A groove portion 30 recessed in the axial direction of the crankpin 5 is formed in the portion of the lower link upper 6A between the second straight portion 16 and the crankpin bearing portion 11 of each end surface 27 for weight reduction. formed. The groove 30 has a substantially square shape when viewed from the axial direction of the crankpin 5 .

Similarly, a groove portion 31 recessed in the axial direction of the crankpin 5 is formed at a portion of the lower link lower portion 6B on the opposite side of the groove portion 30 with respect to the crankpin bearing portion 11 in each end face 27 for weight reduction. there is The groove 31 has a substantially square shape when viewed from the axial direction of the crankpin 5 .

The weight portion 10 is formed integrally with the lower link lower 6B on the side of the control pin fitting hole 23 of the lower link lower 6B, and is positioned near the center C1 of the crankpin bearing portion 11 of the lower link 6 with respect to the center of gravity G1 of the basic shape. By shifting the center of gravity toward the control pin fitting hole 23, vibration components associated with the vertical motion of the upper link 3 and yaw and pitch vibrations of the internal combustion engine caused by these vibration components are suppressed. The weight portions 10 extend radially outward of the crank pin bearing portion 11 from the control pin pin boss portions 21a, 21a in the lower link lower portion 6B in a generally fan shape. In other words, the weight portion 10 extends radially outward of the crankpin bearing portion 11 from a substantially V-shape formed by a portion of the first straight portion 15, a portion of the arc portion 19, and a portion of the second straight portion 17. , extending along the end surface 27 of the lower link 6, on both sides of a line E passing through the center C1 of the crankpin bearing portion 11, the center C2 of the control pin fitting hole 23, and the center C3 of the upper pin fitting hole 22. It is roughly evenly distributed. The shape of the weight portion 10 configured in this manner prevents the weight portion 10 from interfering with the cylinder block (not shown) when the lower link 6 rotates.

The center of gravity G2 of the lower link 6 including the weight portion 10 is located at a position shifted from the center C1 of the crankpin bearing portion 11 toward the control pin fitting hole 23 side. Furthermore, the center of gravity G2 is located on the line segment C1-C2 at a position shifted toward the control pin fitting hole 23 from the center of gravity G1 of the basic shape of the lower link 6. As shown in FIG.

In such a multi-link type piston crank mechanism, the lower link 6 receives the combustion pressure received by the piston 1 via the upper link 3 by means of the upper pin 4, and exerts force on the crank pin 5 by swinging with the control pin 9 as a fulcrum. introduce.

FIG. 4 shows the results of a straight three-cylinder internal combustion engine when a lower link having a substantially parallelogram basic shape, ie, a lower link without a weight, is used and when the lower link 6 of the first embodiment is used. Each shows a change in the amplitude of the yaw oscillation. In FIG. 4, the horizontal axis indicates time, while the vertical axis indicates the magnitude of yaw oscillation. The dashed line shows the change in yaw vibration amplitude when the lower link without weight is used, while the solid line shows the change in yaw vibration amplitude when the lower link 6 of the first embodiment is used. is shown.

As shown in FIG. 4, the amplitude of yaw vibration when using the lower link 6 of the first embodiment is smaller than the amplitude of yaw vibration when using a lower link without a weight. Therefore, it can be seen that adding the weight portion 10 to the lower link lower 6B reduces the yaw vibration generated in the in-line three-cylinder internal combustion engine.

As described above, in the first embodiment, the weight portion 10 is configured from a substantially V-shaped portion composed of a portion of the first straight portion 15, a portion of the arc portion 19 and a portion of the second straight portion 17 to a crank angle. It protrudes radially outward of the pin bearing portion 11 . Therefore, the center of gravity G2 of the lower link 6 including the weight portion 10 is set to the center of gravity G1 of the substantially parallelogram basic shape set to ensure the minimum rigidity of the lower link 6. It is in a position shifted to the 23 side. As a result, the generation of vibration components associated with the vertical motion of the upper link 3 is suppressed, and yaw vibration and pitch vibration generated in the in-line three-cylinder internal combustion engine accompanying these vibration components are reduced. That is, as shown in FIG. 5, when the lower link 6 (point B) of the first embodiment is used, the magnitudes of yaw vibration and pitch vibration are similar to those of the lower link having a substantially parallelogram basic shape, that is, The magnitude of the yaw vibration and the pitch vibration is smaller than when a lower link without a weight (point A) is used. Therefore, the noise and vibration performance of the in-line three-cylinder internal combustion engine due to yaw vibration and pitch vibration is improved.

In FIG. 5, the magnitude of pitch vibration on the horizontal axis indicates that pitch vibration increases toward the right side of FIG. 5, while the magnitude of yaw vibration on the vertical axis indicates the magnitude of It shows that the yaw oscillation increases toward

Further, when the multi-link type piston crank mechanism has a long stroke for the purpose of improving fuel efficiency, the noise and vibration performance of the in-line three-cylinder internal combustion engine may be further deteriorated. 6 can improve the noise and vibration performance even for the long-stroke multi-link piston crank mechanism as described above.

FIG. 6 shows the lower link 6 of the second embodiment.

In the second embodiment, as shown in FIG. 5, the weight portions 26 of the lower link lower 6B are distributed above the line E passing through the centers C1, C2, and C3.

Accordingly, the center of gravity G3 of the lower link 6 including the weight portion 26 is positioned above the line E.

The lower link 6 having the center of gravity G3 deviated above the line E as in the second embodiment further suppresses the generation of the vibration component associated with the vertical motion of the upper link 3, which occurs in the in-line three-cylinder internal combustion engine. Yaw vibration is further reduced. That is, as shown in FIG. 5, the magnitude of the yaw vibration when the lower link 6 (point C) of the second embodiment is used is is smaller than the magnitude of the yaw oscillation in the case. This further improves the noise and vibration performance of the in-line three-cylinder internal combustion engine.

FIG. 7 shows the lower link 6 of the third embodiment.

In the third embodiment, the lower link 6 is formed in the above-described basic shape of the parallelogram so as to secure the required rigidity as a single piece of the lower link 6 and to minimize the weight of the lower link 6. It is In the lower link 6, the upper pin fitting hole 22 side of the line F perpendicular to the line E passing through the centers C1, C2 and C3, and the control pin fitting hole 23 side of the SCR420H having a specific gravity of 7.8. A light weight portion 32 made of a material having a low specific gravity is provided. The lightweight portion 32 has first to third small and lightweight portions 32a, 32b, and 32c indicated by dots in FIGS. 7 and 8, and is made of a synthetic resin material such as Kobelite KM-9000. Here, the specific gravity of Koberite KM-9000 is 1.32.

A portion of the bottom portion 28a of the groove portion 28 that is close to the upper pin fitting hole 22 and the crankpin bearing portion 11 is a portion that is smaller in thickness than the upper pin pin boss portion 20a as shown in FIG. A substantially circular first hole portion 33 is formed through the pin 5 in the axial direction thereof. As shown in FIGS. 7 and 8, the first hole portion 33 is filled with a first small and light portion 32a made of Koberite KM-9000.

Further, the central portion of the bottom portion 28a of the groove portion 28 in the direction along the first straight portion 14 is continuous from the bottom portion 28a of the groove portion 28 on the front side in FIG. A substantially circular second hole portion 34 is formed through this portion so as to extend therethrough in the axial direction of the crankpin 5 . The second hole 34 is filled with a second light weight portion 32b made of Kobelite KM-9000.

Approximately half of the bottom portion 30a of the groove portion 30 on the side of the second straight portion 16 is smaller than the thickness of the upper pin pin boss portion 20a as shown in FIG. A third hole portion 35 is formed through the pin 5 in the axial direction thereof, and the third hole portion 35 is filled with a third light weight portion 32c made of Kobelite KM-9000.

The connection between the outer peripheral surface of the first small and light portion 32a and the inner peripheral surface of the first hole 33, the connection between the outer peripheral surface of the second small and light portion 32b and the inner peripheral surface of the second hole 34, In addition, the bonding between the outer peripheral surface of the third small and light portion 32c and the inner peripheral surface of the third hole portion 35 is performed by a known dissimilar material bonding method.

In order to prevent the first to third small and light portions 32a, 32b, 32c from falling out of the first to third holes 33, 34, 35, the first to third holes 33, 34, 35 are You may make it provide unevenness|corrugation in an internal peripheral surface.

Further, in the third embodiment, the substantially V-shaped portion of the lower link upper 6A, which is composed of a portion of the first straight portion 14, a portion of the arc portion 18, and a portion of the second straight portion 16, A small and lightweight portion is provided in an arcuate portion (a portion between the upper pin fitting hole 22 and the first and third small and light portions 32a, 32c) surrounding the upper pin fitting hole 22 which is continuous with the portion. Instead, the metal portion made of SCR420H is continuous. The V-shaped portion and the arc-shaped portion are likely to be subjected to loads caused by the vertical movement of the piston and upper link. There is.

The center of gravity G4 of the lower link 6 including the first to third small and light portions 32a, 32b, 32c is located at a position shifted from the center C1 of the crankpin bearing portion 11 toward the control pin fitting hole 23 side. Further, the center of gravity G4 is located on the line segment C1-C2 at a position shifted toward the control pin fitting hole 23 from the center of gravity G1 of the basic shape of the lower link 6. As shown in FIG.

As described above, in the third embodiment, on the upper pin fitting hole 22 side of the line F of the lower link 6, the first to third small and lightweight materials made of a material having a smaller specific gravity than the control pin fitting hole 23 side are provided. Portions 32a, 32b and 32c are provided. Therefore, the center of gravity G4 of the lower link 6 including the first to third small and light weight portions 32a, 32b, 32c is the center of gravity of the basic shape of a substantially parallelogram set to ensure the minimum rigidity of the lower link 6. It is at a position shifted toward the control pin fitting hole 23 with respect to G1. As a result, the generation of vibration components associated with the vertical motion of the upper link 3 is suppressed, and yaw vibration and pitch vibration generated in the in-line three-cylinder internal combustion engine accompanying these vibration components are reduced.

FIG. 9 shows the lower link 6 of the fourth embodiment.

The lower link 6 of the fourth embodiment has a weight portion 36 having a smaller outer shape than the weight portion 10 of the first embodiment on the control pin fitting hole 23 side of the lower link lower 6B of the lower link 6 of the third embodiment. is added. Therefore, the center of gravity G5 of the lower link 6, including the first to third light weight portions 32a, 32b, 32c and the weight portion 36, is greater than the center of gravity G4 of the third embodiment on the line segment C1-C2. It is in a position shifted to the joint hole 23 side.

As in the fourth embodiment, the lower link 6 including the first to third light weight portions 32a, 32b, 32c and the small weight portion 36 also shifts the center of gravity G5 toward the control pin fitting hole 23 side. is obtained. Therefore, the small weight portion 36 can effectively suppress interference between the weight portion 36 and the cylinder block, and reduce yaw vibration and pitch vibration occurring in the in-line three-cylinder internal combustion engine.

Reference Signs List 1 Piston 3 Upper link 6 Lower link 6A Lower link upper 6B Lower link lower 7 Control link 10 Weight portion 11 Crankpin bearing portion 14 , 15... First straight parts 16, 17... Second straight parts 18, 19... Arc part 23... Control pin fitting hole 26... Weight parts C1, C2, C3. Center G1, G2, G3, G4, G5 Center of gravity 32 Lightweight portions 32a, 32b, 32c First to third small and light portions 33, 34, 35 First to third 3 holes 36: weight

Claims (5)

An upper link having one end connected to a piston via a piston pin, a lower link connected to the other end of the upper link via an upper pin and to a crankpin of a crankshaft, and one end connected to an internal combustion engine body. a control link pivotably connected and the other end connected to the lower link via a control pin,
The lower link is provided with an upper pin fitting hole into which the upper pin is fitted and a control pin fitting hole into which the control pin is fitted on both sides of the crank pin bearing portion into which the crank pin is fitted. and
The lower link has a pair of first linear portions facing each other with the crankpin bearing portion interposed therebetween, and a pair of second straight portions having a predetermined angle with respect to the pair of first linear portions and facing each other. and two arcuate portions connecting the first straight portions and the second straight portions on the upper pin fitting hole side and the control pin fitting hole side to form a substantially rectangular basic shape. is formed and has an end face along a plane orthogonal to the upper pin;
A groove recessed in the axial direction of the crankpin is provided between the crankpin bearing portion and a first straight portion or a second straight portion on the upper pin fitting hole side of the end face,
A multi-link piston crank mechanism, wherein a light-weight portion made of a material having a relatively small specific gravity is provided in a hole provided in the bottom of the groove . 2. The multi-link type piston crank mechanism according to claim 1 , wherein the light weight portion is made of a synthetic resin material, and the portion of the lower link other than the light weight portion is made of a metal material. . 3. The multi-link piston according to claim 1 , wherein the center of gravity of the lower link including the light weight portion is positioned closer to the control pin fitting hole than the center of the crankpin bearing portion. crank mechanism. a substantially V-shaped portion and the V-shaped portion of the lower link, which are composed of a portion of the first straight portion, an arc portion, and a portion of the second straight portion on the upper pin fitting hole side; A multi-link piston crank mechanism according to any one of claims 1 to 3 , wherein the arcuate portion surrounding said continuous upper pin fitting hole is made of metal. The multi-link piston crank mechanism according to any one of claims 1 to 4 , wherein the lower link is used in an odd-numbered cylinder internal combustion engine.

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