JP7567429B2 - Method for forming link member and link member - Google Patents

Description

The present invention relates to a link member.

Patent Document 1 discloses a variable compression ratio engine. This variable compression ratio engine has an upper link whose lower end is connected to a lower link via a pin and whose upper end is connected to a piston via a pin.

JP 2010-242583 A

The pins slide at the joints that connect the link members. For this reason, it is desirable to efficiently supply lubricating oil to the joints of the link members.

The present invention was made in consideration of these problems, and aims to efficiently supply lubricating oil to the connecting parts of the link members.

A method for forming a link member according to one embodiment of the present invention is a method for forming a link member having a shaft portion, a connecting portion, and a lubricating oil passage extending axially through the shaft portion and opening into the connecting portion, with an oil reservoir gap formed in at least one end region of the lubricating oil passage, the method including: supplying a metal material, melting and solidifying the supplied metal material with laser light to form a metal layer, and stacking the metal layer in multiple layers in the axial direction at a predetermined pitch through three-dimensional modeling to form a stepped inner surface at least on the axial outside of the oil reservoir gap, thereby forming the link member.

According to another aspect of the present invention, there is provided a link member having a shaft portion, a connecting portion, and a lubricating oil passage extending axially through the shaft portion and opening into the connecting portion, with an oil reservoir gap formed at least in one end region of the lubricating oil passage, and with a stepped inner surface at least on the axially outer side of the oil reservoir gap.

According to these aspects, the oil reservoir gap has a stepped inner surface at least on the axially outer side, so that a portion of the lubricating oil supplied to the oil reservoir gap can be collected by the stepped inner surface and dropped into the oil reservoir gap. As a result, the amount of lubricating oil held in the oil reservoir gap and supplied to the connecting portion increases, so that the lubricating oil can be efficiently supplied to the connecting portion of the link member.

FIG. 1 is a schematic configuration diagram of an engine. 1A to 1C are explanatory diagrams of a method for forming a workpiece by three-dimensional modeling. FIG. FIG. FIG. 2 is an explanatory diagram of a first oil collection mode by a first oil pocket. FIG. 13 is a diagram showing how oil is collected on a stepped inner surface. FIG. 11 is an explanatory diagram of a second oil collection mode by a first oil pocket. FIG. 11 is an explanatory diagram of a third oil collection mode by a first oil pocket. FIG. 11 is a first explanatory diagram of a stress acting on an upper link. FIG. 11 is a second explanatory diagram of the stress acting on the upper link. 13A and 13B are diagrams showing a connecting rod which is a modified example of the link member;

The following describes an embodiment of the present invention with reference to the attached drawings.

Figure 1 is a schematic diagram of an engine 1. The engine 1 is an internal combustion engine, and includes a piston 2, an upper link 3, a lower link 4, a crankshaft 5, a control link 6, a control shaft 7, a pinion 8, an actuator 9, an oil jet 10, a piston pin 11, a connecting pin 12, a connecting pin 13, and a connecting pin 14.

Engine 1 is a variable compression ratio engine with a multi-link mechanism that connects piston 2 and crankshaft 5 with two links, upper link 3 and lower link 4, and the mechanical compression ratio of engine 1 is made variable by changing the top dead center position of piston 2. In engine 1, the compression ratio is changed by adjusting the position of lower link 4 with control link 6.

The upper link 3 is connected at its upper end to the piston 2 by a piston pin 11. The lower link 4 is connected at one end to the lower end of the upper link 3 by a connecting pin 12, and at the other end to the upper end of the control link 6 by a connecting pin 13. The lower link 4 has a connecting hole in the center, into which the crank pin 5a of the crankshaft 5 is inserted. The crank pin 5a is provided at a position eccentric to the crank journal 5b of the crankshaft 5, and connects the lower link 4 to the crankshaft 5 so that it can swing freely around the crank pin 5a.

The control link 6 is connected at its upper end to the lower link 4 by a connecting pin 13, and at its lower end to the control shaft 7 by a connecting pin 14. The control shaft 7 is arranged parallel to the crankshaft 5, and the connecting pin 14 is provided at a position eccentric from the center. The control shaft 7 has a gear formed on its outer periphery that engages with the pinion 8. The actuator 9 rotates the pinion 8 to rotate the control shaft 7, and changes the position of the lower link 4 through the movement of the connecting pin 14. The oil jet 10 sprays oil toward the underside of the crown surface of the piston 2 and the upper link 3. Lubricating oil is used as the oil.

The upper link 3 is formed by three-dimensional modeling, as described below.

Figure 2 is an explanatory diagram of a method for forming a workpiece W by three-dimensional modeling. Figure 2 shows a case where the workpiece W is a container. As shown in Figures 1 and 2, a 3D printer 20 is used for three-dimensional modeling. The 3D printer 20 is a three-dimensional modeling device, and has an elevator 21, rollers 22, a scanning device 23, and a laser light source 24.

Base B is placed on the table of elevator 21. Metal material in powder form is supplied to base B by rollers 22, thereby forming material layer L1. The metal material supplied to base B by rollers 22 can be supplied separately. Scanning device 23 irradiates material layer L1 while scanning with laser light 25 from laser light source 24. Scanning device 23 scans laser light 25 based on 3D CAD data of workpiece W. The material layer L1 in the portion irradiated with laser light 25 is melted and solidified as shown in the top view of Figure 1, and is formed into metal layer L2. Figure 1 shows the state in which the formation of the first metal layer L2 is almost completed.

When the first metal layer L2 is formed, the elevator 21 descends a predetermined pitch, and the second metal layer L2 is formed in the same manner. As a result, the metal layers L2 are stacked. The predetermined pitch is a changeable setting value, and is set to 0.05 mm, for example. Figure 2 shows the state in which the metal layers L2 are stacked in multiple layers, and the three-dimensional modeling of the workpiece W by the 3D printer 20 is almost completed. The formed workpiece W is removed from the 3D printer 20 together with the material layer L1 that is not irradiated with the laser light 25, together with the base B, as shown in Figure 3. Thereafter, the material layer L1 is removed as shown in Figure 4, and the workpiece W is further separated from the base B as shown in Figure 5, completing the workpiece W as shown in Figure 6.

In this embodiment, the upper link 3 is formed by stacking multiple metal layers L2 with the axial direction aligned with the ascending and descending direction of the elevator 21 through this type of three-dimensional modeling. As a result, the upper link 3 is layer-modeled in the 3D printer 20 as a vertical wall. Next, the upper link 3 formed in this manner will be further described.

Figure 3 is an external view of the upper link 3. Figure 4 is a cut model view of the upper link 3. Figure 4 shows a cut model of the upper link 3 in a vertical section along the first width direction W1, which is the extension direction of the first pin hole 321 and the second pin hole 331. The second width direction W2 indicates a width direction perpendicular to the first width direction W1. The upper link 3 has a shaft portion 31, a first connecting portion 32, a second connecting portion 33, a first oil hole 34, a second oil hole 35, a lubricating oil passage 36, a first oil pocket 37, a second oil pocket 38, a first recessed portion 39, and a second recessed portion 40.

The shaft portion 31 has a convergent shape that gradually becomes thinner toward the center in the axial direction. A first connecting portion 32 is formed at one end, or upper end, of the shaft portion 31, and a second connecting portion 33 is formed at the other end, or lower end. The first connecting portion 32 is a connecting portion with the piston 2, and has a first pin hole 321. The piston pin 11 is provided in the first pin hole 321 via a bearing metal. The second connecting portion 33 is a connecting portion with the lower link 4, and has a second pin hole 331. The connecting pin 12 is provided in the second pin hole 331 via a bearing metal.

The first oil hole 34 is provided on the upper end side of the upper link 3, and the second oil hole 35 is provided on the lower end side of the upper link 3. The first oil hole 34 communicates with a first oil pocket 37 formed in the upper link 3, and the second oil hole 35 communicates with a second oil pocket 38 formed in the upper link 3. The first oil hole 34 and the second oil hole 35 each penetrate the shaft portion 31 along the second width direction W2. The first oil hole 34 and the second oil hole 35 each have a shape that gradually narrows toward the center in the axial direction. Oil sprayed from the oil jet 10 flows into the first oil hole 34 and the second oil hole 35.

The lubricating oil passage 36 extends in the axial direction of the shaft portion 31 and opens into the second connecting portion 33. A first oil pocket 37 is formed in the upper end region of the lubricating oil passage 36, i.e., the end region on the piston 2 side. A second oil pocket 38 is formed in the lower end region of the lubricating oil passage 36, i.e., the end region on the lower link 4 side. The first oil pocket 37 and the second oil pocket 38 are both oil pool voids and hold oil supplied to the second connecting portion 33. The lubricating oil passage 36 opens into the lower end of the first oil pocket 37 and penetrates the second oil pocket 38 in the axial direction to open into the second pin hole 331 of the second connecting portion 33. The bearing metal provided in the second pin hole 331 has an oil groove formed on the inner surface along the circumferential direction, and an oil hole is formed that communicates the oil groove with the lubricating oil passage 36 that opens into the second pin hole 331.

The first recess 39 is formed at the upper end of the shaft portion 31, and the second recess 40 is formed at the lower end of the shaft portion 31. The first recess 39 and the second recess 40 are formed on both side surfaces of the shaft portion 31 located in the first width direction W1. The first recess 39 and the second recess 40 each have a width in the second width direction W2. The first recess 39 and the second recess 40 each have a shape whose width gradually narrows toward the center in the axial direction.

As shown in FIG. 3, both end faces of the first connecting part 32 where the first pin hole 321 opens have a tapered shape that gradually narrows toward the upper end side of the upper link 3. The tapered shape is formed on the upper part of both end faces of the first connecting part 32, and enables the piston pin 11 to efficiently receive oil supplied to the underside of the crown surface of the piston 2.

As shown in FIG. 4, the lubricating oil passage 36 connects the first oil pocket 37 and the second oil pocket 38. The first oil pocket 37 and the second oil pocket 38 hold oil supplied from the oil jet 10. The second oil pocket 38 further holds oil that flows from the first oil pocket 37 via the lubricating oil passage 36. Each of the first oil pocket 37 and the second oil pocket 38 secures the oil to be supplied to the second connecting portion 33, thereby enabling oil to be efficiently supplied to the second connecting portion 33 so that insufficient lubrication does not occur.

As shown in FIG. 4, the lubricating oil passage 36, the first oil pocket 37, and the second oil pocket 38 each have a converging shape that gradually narrows toward the axial center. Therefore, the first oil pocket 37 is formed in a funnel shape, and the lubricating oil passage 36, which is formed in a funnel shape at the upper end side, is connected to the first oil pocket 37. This allows the oil supplied from the oil jet 10 into the first oil pocket 37 to be efficiently supplied to the second connecting portion 33 via the lubricating oil passage 36. In the first oil pocket 37, the oil sprayed from the oil jet 10 is collected as described below.

Figure 5 is an explanatory diagram of the first oil collection mode by the first oil pocket 37. Figure 6 is a diagram showing the state in which oil is collected on the stepped inner surface 371a. In Figure 5, the peripheral portion of the first oil pocket 37 is shown in a longitudinal section along the second width direction W2. As shown by multiple arrows in Figure 5, the oil spray injected from the oil jet 10 to the first oil pocket 37 includes oil that proceeds without colliding with the upper link 3 and oil that is supplied into the first oil pocket 37. The oil that proceeds without colliding with the upper link 3 is supplied to the back side of the crown surface of the piston 2. The oil supplied into the first oil pocket 37 reaches the axially outer side of the first oil pocket 37, i.e., the upper inner surface 371.

As described above, the upper link 3 is formed by three-dimensional modeling, which involves additive manufacturing at a predetermined pitch. Therefore, the inner surface 371 has a stepped inner surface 371a formed by additive manufacturing. The oil that reaches the stepped inner surface 371a is collected by the step portions of the stepped inner surface 371a as shown in FIG. 6. The stepped portions of the stepped inner surface 371a make it possible to collect oil droplets of various sizes. The oil collected by the stepped inner surface 371a then falls into the first oil pocket 37 as shown in FIG. 5. This increases the amount of oil held in the first oil pocket 37 and supplied to the second connecting portion 33, so that oil is supplied to the second connecting portion 33 efficiently.

The pitch P shown in FIG. 6 indicates the predetermined pitch when the first oil pocket 37 is formed. The predetermined pitch is enlarged when the first oil pocket 37 is formed compared to normal times, that is, when other parts other than the first oil pocket 37 are formed. Therefore, the pitch P is larger than the predetermined pitch in normal times. In this embodiment, the predetermined pitch is set to 0.05 mm in normal times, and 0.08 mm when the first oil pocket 37 is formed. As a result, the surface formed by layered molding is smooth in normal times, and when the first oil pocket 37 is formed, the step of the stepped inner surface 371a is enlarged, making it easier to collect oil. On the other hand, when the first oil pocket 37 is formed, in which the predetermined pitch is enlarged, the irradiation energy of the laser light 25 is larger than in normal times. Therefore, by layered molding at a predetermined pitch of 0.05 mm in normal times, it is possible to form a vertical wall with high density and high strength while suppressing the irradiation energy.

Figure 7 is an explanatory diagram of the second oil collection mode by the first oil pocket 37. Figure 7 shows a cross section of the periphery of the first oil pocket 37. In the first oil pocket 37, a stepped inner surface 372a is also formed on the side surface 372 of the first oil pocket 37. The stepped inner surface 372a is formed by scanning the laser light 25 in each layer. The stepped inner surface 372a makes it easier for oil to be collected on the side surface 372 of the first oil pocket 37, so the amount of oil held in the first oil pocket 37 and supplied to the second connecting portion 33 increases.

Figure 8 is an explanatory diagram of the third oil collection mode by the first oil pocket 37. Figure 1 shows the case where the piston 2 moves from the top dead center to the bottom dead center. Figure 2 shows the case where the piston 2 reaches the bottom dead center. The inner surface 371 further has a flat surface 371b. The flat surface 371b is formed inside the stepped inner surface 371a, that is, in the center of the inner surface 371, and faces the lubricating oil passage 36. When the piston 2 moves from the top dead center to the bottom dead center, the flat surface 371b holds oil as shown in Figure 1, thereby increasing the amount of oil held in the first oil pocket 37 and supplied to the second connecting part 33. When the piston 2 reaches the bottom dead center, the oil held in the flat surface 371b falls from the flat surface 371b due to inertial force and falls into the lubricating oil passage 36 as shown in Figure 2, and is supplied to the second connecting part 33 via the lubricating oil passage 36.

The upper link 3 is designed to be strong against stress σ and lightweight, as explained below.

Figure 9 is a first explanatory diagram of the stress σ acting on the upper link 3. In Figure 9, the upper link 3 is shown in a vertical end surface along the first width direction W1. A load F1 acts on the upper link 3 from the piston pin 11 through the first pin hole 321, and a load F2 acts on the upper link 3 from the connecting pin 12 through the second pin hole 331. In the shaft portion 31, the portions on both sides of the first width direction W1 of the first oil pocket 37 and the portions on both sides of the first width direction W1 of the second oil pocket 38 extend toward the center and inward in the axial direction. Therefore, the load F1 generates axially central and inward stresses σ1 and σ2 in the portions on both sides of the first width direction W1 of the first oil pocket 37. In addition, the load F2 generates axially central and inward stresses σ3 and σ4 in the portions on both sides of the second oil pocket 38 in the first width direction W1.

The stresses σ1 and σ3 on one side (left side in the figure) of the first width direction W1 tend to displace the shaft portion 31 in the displacement direction D1 from one side to the other side (right direction in the figure). The stresses σ2 and σ4 on the other side (right side in the figure) of the first width direction W1 tend to displace the shaft portion 31 in the displacement direction D2 from the other side to one side (left direction in the figure). In other words, in the upper link 3, the stresses σ1 and σ4, which are distributed in a balanced manner in four directions by the shaft portion 31 having a convergent shape, the first oil pocket 37, and the second oil pocket 38, act to suppress the displacement of the shaft portion 31. As a result, the displacement of the shaft portion 31 in the first width direction W1 is suppressed, resulting in a shape that is strong against the stress σ and a reduction in weight.

Figure 10 is a second explanatory diagram of the stress σ acting on the upper link 3. Figure 10 shows the upper link 3 viewed along the axial direction of the first pin hole 321 and the second pin hole 331. As described above, the first recessed portion 39 and the second recessed portion 40 each have a shape in which the width gradually narrows toward the axial center. Therefore, in the shaft portion 31, the portions on both sides of the second width direction W2 of the first recessed portion 39 and the portions on both sides of the second width direction W2 of the second recessed portion 40 extend toward the axial center and inward. As a result, the load F1 generates axially central and inward stresses σ5 and σ6 in the portions on both sides of the second width direction W2 of the first recessed portion 39. In addition, the load F2 generates axially central and inward stresses σ7 and σ8 in the portions on both sides of the second width direction W2 of the second recessed portion 40.

The stresses σ5 and σ7 on one side of the second width direction W2 tend to displace the shaft 31 in the displacement direction D3 from one side to the other side. The stresses σ6 and σ8 on the other side of the second width direction W2 tend to displace the shaft 31 in the displacement direction D4 from the other side to the one side. In other words, in the upper link 3, the stresses σ5 to σ8 distributed in a well-balanced manner in four directions by the first recess 39 and the second recess 40 act to suppress the displacement of the shaft 31. As a result, the displacement of the shaft 31 in the second width direction W2 is also suppressed, resulting in a shape that is even stronger against the stress σ and a lighter weight.

Next, we will explain the main effects of this embodiment.

The method for forming a link member according to this embodiment is used for an upper link 3 as a link member having a shaft portion 31, a second connecting portion 33, and a lubricating oil passage 36 that extends axially through the shaft portion 31 and opens into the second connecting portion 33, with a first oil pocket 37 formed in at least an upper end region that is an area on one end side of the lubricating oil passage 36. The method for forming a link member according to this embodiment includes supplying a metal material, melting and solidifying a material layer L1 made of the supplied metal material with a laser beam 25 to form a metal layer L2, and forming the upper link 3 as a link member by three-dimensional modeling in which a plurality of layers of the metal layer L2 are stacked in the axial direction at a predetermined pitch.

The upper link 3 as a link member in this embodiment has a shaft portion 31, a second connecting portion 33, and a lubricating oil passage 36 that extends axially through the shaft portion 31 and opens into the second connecting portion 33. The link member has a first oil pocket 37 formed in at least the upper end region, which is the region on one end side of the lubricating oil passage 36, and has a stepped inner surface 371a at least on the upper side of the first oil pocket 37, i.e., at least on the axially outer side.

With this method and link member, the first oil pocket 37 has a stepped inner surface 371a at least on the axially outer side. Therefore, a portion of the oil supplied to the first oil pocket 37 can be collected by the stepped inner surface 371a and dropped into the first oil pocket 37. As a result, the amount of oil held in the first oil pocket 37 and supplied to the second connecting portion 33 increases, so that oil can be supplied to the second connecting portion 33 efficiently.

In this embodiment, in engine 1, which is a variable compression ratio engine that changes the mechanical compression ratio, piston 2 and lower link 4 are connected, and upper link 3 having first oil pocket 37 formed at least in the upper end region of lubricating oil passage 36, i.e., the end region on the piston 2 side, constitutes a link member. In this case, in engine 1, which has a structure in which connecting pin 12 connecting upper link 3 and lower link 4 slides, oil can be efficiently supplied to second connecting portion 33, where smooth oil supply is an issue due to the structure.

In this embodiment, the specified pitch is enlarged when forming the first oil pocket 37 compared to when forming other parts other than the first oil pocket 37. This makes it easier to collect oil by enlarging the step of the stepped inner surface 371a when forming the first oil pocket 37.

In this embodiment, the specified pitch is 0.08 mm when forming the first oil pocket 37, and 0.05 mm when forming the other parts other than the first oil pocket 37. This makes it possible to form a vertical wall with high density and strength while suppressing the irradiation energy when forming the other parts other than the first oil pocket 37.

Next, we will explain modified examples of the link member.

Figure 11 is a diagram showing a connecting rod 51, which is a modified example of a link member. The engine 50 connects the piston 52 and the crankshaft 53 with the connecting rod 51, and does not have a multiple link mechanism. The connecting rod 51 has a shaft portion 511, a connecting portion 512 connected to the crank pin 531 of the crankshaft 53, and a lubricating oil passage 513 that extends the shaft portion 511 in the axial direction and opens to the connecting portion 512. The connecting rod 51 is a link member in which an oil pocket 514, which is an oil pool void, is formed in the upper end region, which is the region on one end side of the lubricating oil passage 513, and at least the rod body of the rod body and the cap is formed by three-dimensional modeling. The connecting rod 51 is configured to have a stepped inner surface 514a at least on the upper side of the oil pocket 514, that is, at least on the axial outer side, by forming the rod body by three-dimensional modeling. The lubricating oil passage 513 and the oil pocket 514 have a convergent shape that gradually narrows toward the lower end side, which is the other axial end side. The specified pitch can be set in the same way as when the upper link 3 is three-dimensionally molded.

Even in this case, some of the oil supplied to the oil pocket 514 can be collected by the stepped inner surface 514a and allowed to fall into the oil pocket 514, allowing oil to be efficiently supplied to the connecting portion 512.

Although the embodiments of the present invention have been described above, the above embodiments merely show some of the application examples of the present invention, and are not intended to limit the technical scope of the present invention to the specific configurations of the above embodiments.

1. Engine (variable compression ratio engine)
2 piston 20 3D printer 25 laser light 3 upper link 31 shaft portion 33 second connecting portion (connecting portion)
36 Lubricating oil passage 37 First oil pocket (oil reservoir gap)
371a Stepped inner surface 4 Lower link 50 Engine 51 Connecting rod 511 Shaft portion 512 Connection portion 513 Lubricating oil passage 514 Oil pocket (oil collecting space)
514a Stepped inner surface L1 Material layer L2 Metal layer

Claims (8)

A method for forming a link member having a shaft portion, a connecting portion, and a lubricating oil passage extending in an axial direction of the shaft portion and opening at the connecting portion, the link member having an oil reservoir gap formed at least in one end side region of the lubricating oil passage,
supplying a metal material, melting and solidifying the supplied metal material with a laser beam to form a metal layer, and laminating the metal layer in a plurality of layers at a predetermined pitch in the axial direction to form the link member while forming a stepped inner surface at least on the axial outer side of the oil reservoir gap by three-dimensional modeling;
A method for forming a link member, comprising: A method for forming the link member according to claim 1, comprising the steps of:
The link member is an upper link that connects a piston and a lower link in a variable compression ratio engine that changes the mechanical compression ratio, and the oil sump gap is formed at least in the piston side end region of the lubricating oil passage.
A method for forming a link member comprising the steps of: A method for forming the link member according to claim 1, comprising the steps of:
The link member is a connecting rod of an engine.
A method for forming a link member comprising the steps of: A method for forming the link member according to any one of claims 1 to 3, comprising the steps of:
When forming the oil reservoir gap, the predetermined pitch is made larger than when forming other portions other than the oil reservoir gap.
A method for forming a link member comprising the steps of: A method for forming the link member according to claim 4, comprising the steps of:
When forming the oil reservoir gap, the predetermined pitch is set to 0.08 mm, and when forming the other portion, the predetermined pitch is set to 0.05 mm.
A method for forming a link member comprising the steps of: A link member having a shaft portion, a connecting portion, and a lubricating oil passage extending in an axial direction of the shaft portion and opening at the connecting portion, and an oil reservoir gap is formed at least in one end side region of the lubricating oil passage,
The oil sump cavity has a stepped inner surface at least on an axially outer side thereof.
A link member characterized by: The link member according to claim 6,
In a variable compression ratio engine that changes the mechanical compression ratio, a piston and a lower link are connected to each other, and the oil sump gap is formed at least in the piston side end region of the lubricating oil passage.
A link member characterized by: The link member according to claim 6,
The engine connecting rod,
A link member characterized by:

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