JP6477372B2 - Link connection method - Google Patents

Description

  The present invention relates to a link connection method.

  Patent Document 1 discloses an internal combustion engine having a multi-link piston crank mechanism. The multi-link type piston crank mechanism includes an upper link having one end connected to a piston via a piston pin, and a lower link connected to the other end of the upper link via an upper pin and connected to a crank pin of the crankshaft. A link and a control link that regulates the degree of freedom of the lower link. The upper link and the lower link are rotatably connected to each other via an upper pin, and the control link and the lower link are rotatably connected to each other via a control pin.

  The lower link receives the combustion pressure received by the piston by the upper pin via the upper link, and transmits the force to the crank pin by a swinging operation starting from the control pin.

  Patent Document 2 discloses a rocker arm assembly applied to a valve operating mechanism that drives intake and exhaust valves of an internal combustion engine. In this assembly, the end region of the shaft of the bearing is fixed in the insertion holes of the pair of side walls of the assembly. Further, a diamond-like carbon (DLC) coating is applied to the central region of the shaft in order to reduce friction with the rolling elements. The central region is formed by applying a DLC coating to the central region in a state where the end region of the shaft is masked.

JP 2001-227367 A JP 2010-112343 A

  When the end region where DLC coating is not required is masked as in Patent Document 2 to form the DLC coating in the central region, the coating operation takes time and additional costs are generated.

  Also, it is difficult to mask the end region while clarifying the boundary between the end region and the center region of the shaft, and when the DLC coating remains in the end region because the boundary is unclear There is a possibility that the force for fixing the shaft in the insertion hole is reduced and the shaft is rotated.

In the present invention, both end portions of the connecting pin are press-fitted and fixed to the first pin fitting holes in the two pin boss portions facing each other provided in the first link, and the second portion is connected to the center portion of the connecting pin. A link coupling method in which the second pin fitting hole in the link is rotatably fitted, wherein the second pin fitting hole is fitted to the first pin fitting hole, and the second region is fitted to the second pin fitting hole. in the pin fitting hole and the fitting to the central region, as near the top Kitan area is easily peeled off a diamond-like carbon coating upon stuffing than the central region, the end region of the connecting pin annularly to form a plurality of grooves, subjecting the diamond-like carbon coating on the entire outer peripheral surface of the connecting pin, the connecting pin that is press-fitted to the first pin fitting hole, in the upper Symbol end region diamond The microphone carbon coating are so as to peel.

  That is, the diamond-like carbon coating in at least one end region is peeled off by press-fitting the connecting pin into the first pin fitting hole.

  According to the present invention, since the end region without the DLC coating is formed by press-fitting the connecting pin without masking the end region of the connecting pin, the additional cost associated with masking during the coating operation is eliminated. be able to.

It is composition explanatory drawing of the multiple link type piston crank mechanism of one Example. It is a perspective view of the lower link of one Example. It is explanatory drawing which shows the surface treatment method of an upper pin. It is explanatory drawing which shows the 1st Example of the link coupling | bonding method which concerns on this invention. It is sectional drawing which shows the coupling | bonding state of a lower link upper and an upper link. It is explanatory drawing which shows the 2nd Example of the link coupling | bonding method which concerns on this invention. It is explanatory drawing which shows the 3rd Example of the link coupling | bonding method which concerns on this invention. It is explanatory drawing which shows the 4th Example of the link coupling | bonding method which concerns on this invention.

  Hereinafter, an embodiment of the present invention will be described in detail with reference to the drawings.

  FIG. 1 shows components of a multi-link type piston crank mechanism to which the present invention is applied. This multi-link type piston crank mechanism itself is known from the above-mentioned Patent Document 1 and the like, and an upper link 3 having one end connected to the piston 1 via a piston pin 2 and an upper pin connected to the other end of the upper link 3. A lower link 6 connected via a (connecting pin) 4 and connected to a crankpin 5 of the crankshaft, and a control link 7 that regulates 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 be configured as a variable compression ratio mechanism by making the position of the support pin 8 variable.

  As shown in FIG. 2, the lower link 6 has a cylindrical crankpin bearing portion 10 fitted in the crankpin 5 in the center, and is opposite to each other by about 180 ° across the crankpin bearing portion 10. Two upper pin bosses 11a, 11a facing each other and two control pin pin bosses 12a, 12a facing each other (only one is shown in FIG. 2) are respectively provided at the side positions. ing. The lower link 6 has a parallelogram shape close to a rhombus as a whole, and a lower link upper 6A including upper pin pin bosses 11a and 11a on a split surface 13 passing through the center of the crankpin bearing portion 10, and a control. It is divided into two parts, a lower link lower 6B including pin boss portions 12a, 12a for pins. The lower link upper 6A and the lower link lower 6B are fastened to each other by a plurality of bolts (not shown) after the crank pin bearing portion 10 is fitted into the crank pin 5.

  The upper pin pin boss portions 11a and 11a and the control pin pin boss portions 12a and 12a are configured so as to sandwich the upper link 3 and the control link 7 in the central portion in the axial direction, and extend along the axial end surface of the lower link 6. ing. That is, the pin boss portions 11a, 11a, 12a, and 12a are respectively connected to both end portions in the axial direction of the crank pin bearing portion 10 formed in a cylindrical shape.

  The lower link 6 receives the combustion pressure received by the piston 1 by the upper pin 4 via the upper link 3, and transmits the force to the crank pin 5 by a swinging operation starting from the control pin 9.

  Hereinafter, the link coupling method of the present invention will be described using the upper pin 4 as an example of the connecting pin.

  The end regions 14 and 14 (see FIG. 3) of the upper pin 4 are fixed in the lower side pin fitting holes 17 and 17 of the upper pin pin boss portions 11a and 11a by press-fitting and fixing. A DLC coating 16 is applied to the central region 15 of the upper pin 4 to which the upper link 3 is fitted in order to make the friction coefficient relatively low.

  Next, a surface treatment method for the end regions 14 and 14 and the center region 15 of the upper pin 4 in this embodiment will be described with reference to FIG. In this embodiment, the upper pin 4 has a cylindrical shape with a uniform sectional shape over the entire length. The upper pin 4 may have a cylindrical shape with a uniform cross-sectional shape over the entire length.

  In order to form the end regions 14 and 14 that do not have the DLC coating 16 and the central region 15 that has the DLC coating 16, in this embodiment, first, the lower side pin fitting holes 17 and 17 are respectively fitted. The adhesion strength of the DLC coating 16 is relatively different between the end regions 14 and 14 at both ends to be joined and the central region 15 to be fitted to the upper pin fitting hole 18 (see FIG. 4). Then, the surface of the upper pin 4 is treated. That is, the surfaces of the end regions 14 and 14 and the center region 15 are treated so that the adhesion strength of the DLC coating 16 in the end regions 14 and 14 becomes relatively weak. Here, the end regions 14 and 14 with relatively weak adhesion strength are shown by dots in FIG. When the surface treatment of the upper pin 4 is performed, for example, the entire outer peripheral surface of the upper pin 4 is first polished and then fine grooves are formed in the end regions 14 and 14 in the same direction by machining, for example, cutting. To do. Thereby, while the outer peripheral surface of the center region 15 is generally smooth, a plurality of regular grooves 19 are formed in an annular shape on the outer peripheral surfaces of the end regions 14, 14.

  In addition, you may make it process the outer peripheral surface of the edge part areas 14 and 14 by shot blasting. In this case, a plurality of recesses are formed on the outer peripheral surfaces of the end regions 14 and 14. In the case of processing by shot blasting, shot blasting may be performed in a state where the central region 15 is partially masked in order to obtain a boundary between the end regions 14 and 14 and the central region 15.

  Moreover, you may make it process the outer peripheral surface of the edge part areas 14 and 14 into a rough surface by chemical etching.

  Next, as a coating process, the surface of the upper pin 4 configured as shown in FIG. 3 is cleaned, and the DLC coating 16 (see FIG. 4) is applied to the entire outer peripheral surface of the upper pin 4. The DLC coating 16 is formed by chemical vapor deposition such as physical vapor deposition or plasma CVD. Masking of the end regions 14, 14 is not necessary.

Thus, the adhesion strength of the DLC coating 16 applied to the surface of the upper pin 4 is in accordance with the surface roughness of the upper pin 4, for example, the arithmetic average roughness Ra. The arithmetic average roughness Ra of the upper pins 4 after the surface treatment is, for example, 0.05 to 0.10 μm in the end regions 14 and 14 and 0.02 to 0.03 μm in the central region 15. Therefore, in this embodiment, the adhesion strength of the DLC coating 16 in the end regions 14 and 14 is relatively weak, and the adhesion strength of the DLC coating 16 in the central region 15 is relatively strong. Here, the “adhesion strength” indicates the difficulty of peeling off the DLC coating 16 with respect to the press fitting of the upper pin 4 into the lower side pin fitting holes 17 and 17.

  The arithmetic average roughness Ra is obtained by dividing the sum of a plurality of areas surrounded by the roughness curve and the reference line at a predetermined length by the predetermined length, and as shown in FIG. The arithmetic average roughness obtained for the roughness curve having a plurality of regular grooves 19 in the regions 14, 14 and the arithmetic average roughness obtained for the roughness curve including extreme irregularities in the central region 15. May be the same. However, in this embodiment, the ease of peeling of the DLC coating 16 from the upper pin 4 is important, and even in the special case where the two arithmetic average roughnesses are the same as described above, the end region 14 , 14 can be relatively weakened.

  Next, FIG. 4 shows a press-fitting process for press-fitting the upper pin 4 into the lower side pin fitting holes 17 of the lower link upper 6A. In this embodiment, the inner diameters of the lower side pin fitting holes 17, 17 in the lower link upper 6 </ b> A are set slightly smaller than the outer diameter of the upper pin 4. The inner diameter of the upper side pin fitting hole 18 of the upper link 3 is set slightly larger than the outer diameter of the upper pin 4.

  In this press-fitting step, as shown in the drawing, the upper link 3 is disposed between the upper pin pin boss portions 11a, 11a of the lower link upper 6A, and the lower side pin fitting holes 17, 17 of the pin boss portions 11a, 11a, The upper side pin fitting hole 18 of the upper link 3 is aligned.

  Then, the upper pin 4 is press-fitted along the arrow A direction. Accordingly, first, the lower end region 14 is press-fitted into the upper lower pin fitting hole 17. At this time, the DLC coating 16 in the lower end region 14 with relatively weak adhesion strength peels off. That is, the DLC coating 16 in the lower end region 14 is peeled off by the annular edge portion 20 of the upper lower pin fitting hole 17.

  Then, by further moving the upper pin 4 in the direction of arrow A, the lower end region 14 from which the DLC coating 16 has been peeled is inserted into the upper side pin fitting hole 18 while the central region 15 is moved to the upper lower side. It passes through the pin fitting hole 17. At this time, the DLC coating 16 in the central region 15 having relatively high adhesion strength remains in the central region 15 without being peeled off by the edge portion 20 even after passing through the upper lower pin fitting hole 17.

  The lower end region 14 not having the DLC coating 16 is press-fitted into the lower lower pin fitting hole 17, and at the same time, the upper end region 14 having the DLC coating 16 is fitted to the upper lower pin fitting hole. It is press-fitted into the hole 17. At this time, the DLC coating 16 in the upper end region 14 having relatively weak adhesion strength is peeled off by the edge portion 20 of the upper lower pin fitting hole 17. Note that the diameter of the upper lower pin fitting hole 17 is slightly enlarged when the lower end region 14 is press-fitted, so that the upper end region 14 becomes the upper lower pin fitting hole 17. When pressed into the lower end region 14, the action of peeling the DLC coating 16 is slightly weaker than when pressed into the lower end region 14. However, at least a part of the DLC coating 16 is peeled off by press-fitting into the upper lower pin fitting hole 17.

  FIG. 5 shows a link coupling structure coupled by the link coupling method of the first embodiment. The lower end region 14 is firmly press-fitted and fixed in the lower lower pin fitting hole 17 without using the DLC coating 16. Although the fixing force may be lower than the lower end region 14, the upper end region 14 is press-fitted and fixed in the upper lower pin fitting hole 17.

  In a state where the lower link upper 6A and the upper link 3 are coupled, the central region 15 having the DLC coating 16 is fitted in the upper side pin fitting hole 18 so as to be rotatable.

  As described above, in the first embodiment, the DLC coating 16 in the at least one end region 14 whose adhesion strength is relatively weakened by the press-fitting of the upper pin 4 is peeled off. The DLC coating 16 can be applied to the central region 15 without masking. This eliminates the additional cost associated with masking.

  In the first embodiment, the adhesion strength of the DLC coating 16 in the end regions 14 and 14 is relatively weakened by cutting the surfaces of the end regions 14 and 14 of the upper pin 4. Therefore, the boundary between the end regions 14 and 14 and the central region 15 can be clarified.

  Since the peeled DLC coating 16 falls outside the upper pin pin boss portion 11a, it does not enter the sliding surface between the end region 14 and the end region 14.

  Next, a second embodiment of the link coupling method according to the present invention will be described with reference to FIG. In this embodiment, a DLC coating removal jig 21 is provided above the upper upper pin boss portion 11a of FIG. The jig 21 includes a jig hole 22 having a diameter equal to or smaller than the diameter of the lower-side pin fitting hole 17 and is divided into two parts so that the jig hole 22 is equally divided. . The diameter of the jig hole 22 is determined by the annular edge 23 of the jig hole 22 when the upper end region 14 is passed through the jig hole 22 with the two-piece jig 21 closed. The size is set such that the DLC coating 16 is peeled off.

  In this embodiment, first, the lower end region 14 is passed through the jig hole 22 with the two-part jig 21 opened, and then the lower end region 14 is passed through the upper lower pin. Press-fit into the fitting hole 17 in the direction of arrow A. As a result, the DLC coating 16 in the lower end region 14 with relatively weak adhesion strength is peeled off by the annular edge portion 20 of the upper lower pin fitting hole 17.

  After the lower end region 14 passes through the upper lower pin fitting hole 17, the split jig 21 is closed, the upper pin 4 is moved along the arrow A direction, and the upper pin 4 The upper end region 14 is passed through the jig hole 22. As a result, the DLC coating 16 in the upper end region 14 with relatively weak adhesion strength is peeled off by the annular edge 23 of the jig 21. Therefore, at the stage of passing through the jig hole 22, both the DLC coatings 16 in the end regions 14 and 14 of the upper pin 4 are peeled off.

  Then, by further moving the upper pin 4 in the direction of arrow A, the lower end region 14 not provided with the DLC coating 16 is press-fitted into the lower lower pin fitting hole 17 and the DLC coating 16 is provided. The upper end region 14 not to be pressed is press-fitted into the upper lower pin fitting hole 17.

  Therefore, according to the second embodiment, the DLC coating 16 in both the end regions 14 and 14 of the upper pin 4 can be reliably removed.

  Next, a third embodiment of the link coupling method according to the present invention will be described with reference to FIG. In this embodiment, the inner diameter of the large-diameter pin fitting hole 24 formed in the upper upper pin boss portion 11a of the lower link upper 6A is the same as the small-diameter pin fitting hole 25 formed in the lower upper pin boss portion 11a. Is set to be larger than the inner diameter. Accordingly, the upper pin 4 is press-fitted into the large-diameter pin fitting hole 25 and the large-diameter pin fitting hole 24 while being rotatably fitted in the upper-side pin fitting hole 18. A small-diameter pin portion 27. Further, a step surface 28 that connects the large-diameter pin portion 26 and the small-diameter pin portion 27 is provided. Furthermore, in this embodiment, by cutting the one end region 29 of the large-diameter pin portion 26 and the surface of the small-diameter pin portion 27, the adhesion strength of the DLC coating 16 on both 29 and 27 is relatively weakened. It is. The DLC coating 16 is coated on the entire upper pin 4.

  In this embodiment, by moving the upper pin 4 in the direction of arrow A, the small-diameter pin portion 27 having the DLC coating 16 is press-fitted into the small-diameter pin fitting hole 25, and at the same time, the large-diameter pin portion 26 having the DLC coating 16. This end region 29 is press-fitted into the large-diameter pin fitting hole 24. At this time, the DLC coating 16 of the small-diameter pin portion 27 having relatively weak adhesion strength is peeled off by the annular edge portion 30 of the small-diameter pin fitting hole 25 and dropped between the upper pin pin boss portions 11a and 11a. The dropped DLC coating 16 is removed from the lower link upper 6A by air blowing. Further, the DLC coating 16 in the end region 29 having relatively weak adhesion strength is peeled off by the annular edge portion 31 of the large-diameter pin fitting hole 24.

  In the link connection state, the large-diameter pin portion 26 and the small-diameter pin portion 27 of the upper pin 4 are firmly press-fitted in the large-diameter pin fitting hole 24 and the small-diameter pin fitting hole 25 without using the DLC coating 16. Yes.

  Therefore, according to the third embodiment, it is possible to reliably peel off the DLC coating 16 on both the end region 29 and the small diameter pin portion 27.

  Next, a fourth embodiment of the link coupling method according to the present invention will be described with reference to FIG. In this embodiment, the adhesion strength of the DLC coating 16 in this end region 14 is relatively weakened by cutting the surface of one end region 14 of the upper pin 4 having a uniform cross-sectional shape over the entire length. .

  The DLC coating 16 in the end region 14 is peeled off by the annular edge portion 20 when it is press-fitted in the upper lower pin fitting hole 17 in FIG.

  In the fourth embodiment, only one end region 14 is firmly pressed into the lower lower pin fitting hole 17 with the DLC coating 16 removed, and the other end region 14 is DLC coated 16. However, depending on the mode of use, sufficient removal strength can be obtained only by removing one of the DLC coatings 16.

  In each of the above embodiments, the example in which the present invention is applied to the upper pin 4 of the lower link 6 has been disclosed, but the present invention may be applied to the control pin 9 side.

  Moreover, although the example of the multi-link type piston crank mechanism in the internal combustion engine has been disclosed in the above embodiment, the present invention can be applied as a link coupling method in various other link mechanisms.

DESCRIPTION OF SYMBOLS 1 ... Piston 3 ... Upper link 4 ... Upper pin 6 ... Lower link 11a ... Upper pin pin boss part 12a ... Control pin pin boss part 14 ... End part region 15 ... Central region 16 ... Diamond like carbon coating 17 ... Lower side pin fitting hole 18 ... Upper side pin fitting hole 21 ... Jig 22 ... Jig hole 24 ... Large diameter Pin fitting hole 25 ... Small diameter pin fitting hole 26 ... Large diameter pin part 27 ... Small diameter pin part

Claims (3)

Both end portions of the connecting pin are press-fitted and fixed to the first pin fitting holes in the two pin boss portions facing each other provided in the first link, and the second link in the second link is fixed to the center portion of the connecting pin. A link coupling method in which two pin fitting holes are rotatably fitted,
And at least one end region for mating with the first pin fitting hole, the at the second pin fitting hole and the fitting to the central region, is the central region towards the upper Kitan region To form a plurality of grooves in an annular shape in the end region of the connecting pin so that the diamond-like carbon coating is more easily peeled off during press fitting ,
Diamond-like carbon coating is applied to the entire outer peripheral surface of this connecting pin,
The connecting pin that is press-fitted to the first pin fitting hole, and so as to peel the diamond-like carbon coating in the upper Symbol end region, the link coupling wherein the.   After the one end region of the connecting pin is press-fitted into the first pin fitting hole, the other end portion is passed through the third hole of the jig by passing the other end region of the connecting pin through the third hole of the jig. The method of claim 1, wherein the diamond-like carbon coating in the region is peeled off. In the multi-link type piston crank mechanism, the first link is a lower link connected to a crank pin of a crankshaft, and the second link is an upper link connected to a piston. The link coupling method according to claim 1 or 2 .

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