Piston connection structure
The piston connecting structure with angled surfaces on the piston pin prevents circlip detachment by expanding the clip body radially outward and minimizing interference, ensuring secure attachment and easy identification.
Patent Information
- Application Number
- JP2022042046
- Authority / Receiving Office
- JP · JP
- Patent Type
- Patents
- Current Assignee / Owner
- Filing Date
- 2022-03-17
- Publication Date
- 2026-01-07
- Estimated Expiration
- 2042-03-17
AI Technical Summary
The piston pin in an engine may move axially and come into contact with the circlip, potentially causing the circlip to fall off.
A piston connecting structure with a piston pin featuring annular tapered surfaces at both ends, forming obtuse and acute angles with the outer surface, is used to prevent the circlip from falling off by expanding the clip body radially outward and avoiding interference with the bent end portions of the circlip.
The angled surfaces on the piston pin effectively prevent the circlips from falling off, ensuring secure attachment and easy control of the piston pin length, while allowing space for engraving identification information.
Smart Images
Figure 0007795384000001 
Figure 0007795384000002 
Figure 0007795384000003
Abstract
Description
[Technical Field]
[0001] The present invention relates to a piston coupling structure. [Background technology]
[0002] The engine has a crankshaft and a piston connected to it via a connecting rod. A piston pin is inserted into the boss of the piston, connecting the piston and the connecting rod to each other via the piston pin. A circlip is attached to the boss of the piston, and the circlip restricts the axial movement of the piston pin. [Prior art documents] [Patent documents]
[0003] [Patent Document 1] Japanese Utility Model Application Publication No. 2-116009 [Patent Document 2] Japanese Utility Model Application Publication No. 2-102072 [Patent Document 3] Japanese Patent Application Publication No. 7-139629 [Patent Document 4] Japanese Utility Model Application Publication No. 54-147876 Summary of the Invention [Problem to be solved by the invention]
[0004] However, when the engine is running, the piston pin may move axially and come into contact with the circlip. Even if the piston pin comes into contact with the circlip, it is necessary to prevent the circlip from falling off.
[0005] An object of the present invention is to prevent a circlip from falling off. [Means for solving the problem]
[0006] A piston connecting structure according to one embodiment is a piston connecting structure for connecting a piston to a connecting rod, the structure comprising: a piston pin inserted into both a pin boss portion formed on the piston and a small end portion formed on the connecting rod; a first circlip attached to a first clip groove formed on the pin boss portion and adjacent to one end of the piston pin; and a second circlip attached to a second clip groove formed on the pin boss portion and adjacent to the other end of the piston pin, wherein both the one end and the other end of the piston pin are formed with a first annular tapered surface extending radially inward from an outer circumferential surface of the piston pin and inclined with respect to a center line of the piston pin, and a second annular tapered surface positioned radially inward of the first annular tapered surface and inclined with respect to the center line, wherein an angle formed between the first annular tapered surface and the second annular tapered surface is an obtuse angle, and an angle formed between the outer circumferential surface and the second annular tapered surface is an acute angle. [Effects of the Invention]
[0007] According to one aspect of the present invention, the angle between the first annular tapered surface and the second annular tapered surface is an obtuse angle, and the angle between the outer circumferential surface and the second annular tapered surface is an acute angle, thereby preventing the circlip from falling off. [Brief explanation of the drawings]
[0008] [Figure 1] 1 is a diagram illustrating an example of a vehicle equipped with an engine. [Figure 2] 1 is a diagram showing an engine equipped with a piston connection structure according to one embodiment of the present invention; [Figure 3] 2 is a diagram showing a piston housed in a cylinder bore and its vicinity; FIG. [Figure 4] FIG. 4 is a cross-sectional view showing the piston and the connecting rod taken along line AA in FIG. 3. [Figure 5] FIG. 2 is an exploded view showing the piston, connecting rod, piston pin, and circlip. [Figure 6] FIG. 4 is a perspective view showing one end of a piston pin. [Figure 7] FIG. 2 is a cross-sectional view showing one end of the piston pin along the centerline of the piston pin. [Figure 8] 2A and 2B are views showing the front, top, bottom and right side of the circlip. [Figure 9] 5 is a view showing the piston pin and its vicinity as viewed from the direction of arrow B in FIG. 4. [Figure 10] FIG. 10 is a cross-sectional view taken along line CC in FIG. 9. [Figure 11] FIG. 10 is a cross-sectional view taken along line CC in FIG. 9. DETAILED DESCRIPTION OF THE INVENTION
[0009] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the following description, identical or substantially identical configurations and elements will be designated by the same reference numerals and will not be described repeatedly.
[0010] [Vehicle configuration] FIG. 1 is a diagram showing an example of a vehicle 11 equipped with an engine 10. As shown in FIG. 1, the vehicle 11 is equipped with a powertrain 12 including the engine 10. As will be described later, the illustrated engine 10 incorporates a piston coupling structure that is an embodiment of the present invention. Wheels 16 are coupled to an output shaft 13 of the powertrain 12 via a propeller shaft 14 and a differential mechanism 15. The powertrain 12 is a rear-wheel drive powertrain, but is not limited to this and may be a front-wheel drive or all-wheel drive powertrain.
[0011] [Engine configuration] FIG. 2 is a diagram showing an engine 10 equipped with a piston connection structure 20 according to one embodiment of the present invention. The engine 10 shown in the figure is a horizontally opposed engine equipped with a pair of cylinder banks, but is not limited to this. For example, the piston connection structure 20, which will be described later, may be employed in an in-line engine, a V-type engine, a single-cylinder engine, or the like. In other words, the piston connection structure 20, which will be described later, can be employed in any type of engine in which the cylinder arrangement or number of cylinders is changed.
[0012] 2, the engine 10 has a cylinder block 21 that constitutes one cylinder bank, a cylinder block 22 that constitutes the other cylinder bank, and a crankshaft 23 supported by the pair of cylinder blocks 21, 22. A cylinder head 27 that is equipped with a valve train 24, an intake port 25, an exhaust port 26, etc. is attached to each of the cylinder blocks 21, 22. An oil pan 28 that stores oil is attached to the bottom of the cylinder blocks 21, 22.
[0013] Each cylinder block 21, 22 is formed with a cylinder bore 30, and each cylinder bore 30 houses a piston 31. A piston pin 32 is attached to the piston 31, and a small end 34 of a connecting rod 33 is connected to the piston pin 32. A big end 36 of the connecting rod 33 is connected to a crank pin 35 of the crankshaft 23. In this way, the crankshaft 23 and the piston 31 are connected to each other via the connecting rod 33.
[0014] [Piston connection structure] Fig. 3 is a diagram showing the piston 31 and its vicinity housed in the cylinder bore 30, and Fig. 4 is a cross-sectional view showing the piston 31 and connecting rod 33 along line AA in Fig. 3. Fig. 5 is an exploded view showing the piston 31, connecting rod 33, piston pin 32, and circlips 51 and 52.
[0015] 3 to 5, the piston 31 has a first boss portion 41 having a pin hole 41a formed therein for supporting one end 32a of the piston pin 32, and a second boss portion 42 having a pin hole 42a formed therein for supporting the other end 32b of the piston pin 32. A first annular clip groove 41b is formed in the pin hole 41a of the first boss portion 41, and a second annular clip groove 42b is formed in the pin hole 42a of the second boss portion 42. In this manner, the piston 31 has a pin boss portion 43 made up of the first boss portion 41 and the second boss portion 42. That is, the pin boss portion 43 of the piston 31 has the first clip groove 41b and the second clip groove 42b formed therein.
[0016] 3 and 4, the connecting rod 33 has an annular small end portion 34 assembled to the piston pin 32, an annular big end portion 36 assembled to the crank pin 35, and a rod portion 37 connecting the small end portion 34 and the big end portion 36 to each other. A bearing 34a is assembled to the small end portion 34 of the connecting rod 33, and a bearing 36a is assembled to the big end portion 36 of the connecting rod 33. The small end portion 34 of the connecting rod 33 is disposed between a first boss portion 41 and a second boss portion 42 formed on the piston 31, and the piston pin 32 is guided in a through hole 34b of the small end portion 34.
[0017] An example of a procedure for connecting the piston 31 and the connecting rod 33 will be described below. As shown by arrow α1 in FIG. 5 , the first circlip 51 is attached to the first clip groove 41b of the first boss portion 41. Next, as shown by arrow α2, the small end portion 34 of the connecting rod 33 is disposed between the first boss portion 41 and the second boss portion 42. Thereafter, as shown by arrow α3, one end portion 32a of the piston pin 32 is inserted from the pin hole 42a of the second boss portion 42 through the through hole 34b of the small end portion 34 into the pin hole 41a of the first boss portion 41. Then, as shown by arrow α4, the second circlip 52 is attached to the second clip groove 42b of the second boss portion 42.
[0018] 3 and 4, the piston 31 and the connecting rod 33 are connected to each other via the piston pin 32. The first circlip 51 provided on the first boss portion 41 is disposed adjacent to one end 32a of the piston pin 32, and the second circlip 52 provided on the second boss portion 42 is disposed adjacent to the other end 32b of the piston pin 32. In other words, the first circlip 51 and the second circlip 52 restrict the axial movement of the piston pin 32 assembled to the piston 31.
[0019] [Piston pin shape] The shape of the end portion of the piston pin 32 will now be described. Fig. 6 is a perspective view showing one end portion 32a of the piston pin 32, and Fig. 7 is a cross-sectional view showing one end portion 32a of the piston pin 32 along the center line CL of the piston pin 32. In the following description, the shape of one end portion 32a of the piston pin 32 will be described, but since the shape of the other end portion 32b of the piston pin 32 is the same as the shape of one end portion 32a, a description of the shape of the other end portion 32b will be omitted. In the following description, the radially inward direction refers to a direction approaching the center line CL of the piston pin 32, and the radially outward direction refers to a direction away from the center line CL of the piston pin 32.
[0020] As shown in FIGS. 6 and 7 , the piston pin 32 has a cylindrical surface, i.e., an outer peripheral surface 60, that is parallel to the center line CL. Furthermore, one end 32a of the piston pin 32 has a first annular tapered surface 61 extending radially inward from the outer peripheral surface 60, an annular flat surface 63 extending radially inward from the first annular tapered surface 61, and a second annular tapered surface 62 extending radially inward from the annular flat surface 63. Thus, one end 32a of the piston pin 32 has the first annular tapered surface 61 disposed radially outward, the second annular tapered surface 62 disposed radially inward from the first annular tapered surface 61, and the annular flat surface 63 disposed between the first annular tapered surface 61 and the second annular tapered surface 62. Furthermore, as shown in FIG. 6 , a part number (piston pin information) 64 of the piston pin 32 is engraved on the second annular tapered surface 62 using a laser or the like. The piston pin information printed on the second annular tapered surface 62 is not limited to the part number 64 of the piston pin 32, but may be the manufacturing number of the piston pin 32, or a one-dimensional code or two-dimensional code containing information about the piston pin 32.
[0021] 7, the first annular tapered surface 61 of the piston pin 32 is inclined with respect to the center line CL of the piston pin 32, and the second annular tapered surface 62 of the piston pin 32 is inclined with respect to the center line CL of the piston pin 32. The annular flat surface 63 of the piston pin 32 is perpendicular to the center line CL of the piston pin 32. The angle A1 between the first annular tapered surface 61 and the second annular tapered surface 62 is an obtuse angle exceeding 90°, and the angle A2 between the outer circumferential surface 60 and the second annular tapered surface 62 is an acute angle less than 90°. The one end 32a of the piston pin 32 is formed with a tapered surface 65 extending radially inward from the second annular tapered surface 62 and an inner circumferential surface 66 extending from the tapered surface 65 and parallel to the center line CL.
[0022] [Circlip shape] Next, the shapes of the circlips 51, 52 will be described. The first circlip 51 and the second circlip 52 have the same shape. FIG. 8 is a diagram showing the front, top, bottom, and right side of the circlips 51, 52. As shown in FIG. 8, the circlips 51, 52 have a clip body 53 made of a wire rod 53a that curves along a predetermined imaginary circle C1. The circlips 51, 52 also have a pair of bent end portions 54, 55 that are bent inward from the clip body 53, i.e., a pair of bent end portions 54, 55 that are bent inward of the imaginary circle C1. Furthermore, the bent end portions 54, 55 of the circlips 51, 52 are crushed so as to be thinner than the clip body 53. The imaginary circle C1 of the circlips 51, 52 is a circle that passes through the center of the cross section of the wire rod 53a that constitutes the clip body 53. In addition, when attaching or detaching the circlips 51, 52 to or from the clip grooves 41b, 42b, the pair of bent ends 54, 55 are pinched using a tool such as pliers, thereby deforming the circlips 51, 52 so as to reduce the radius of curvature of the clip body 53.
[0023] [Contact between piston pin and circlip] The contact state between the piston pin 32 and the circlips 51, 52 will now be described. Fig. 9 is a view showing the piston pin 32 and its vicinity as viewed from the direction of arrow B in Fig. 4, and Fig. 10 is a cross-sectional view taken along line CC in Fig. 9. Fig. 11 is a cross-sectional view showing the same portion as Fig. 10, and Fig. 11 shows the first circlip 51 with its bent end portion 54 deformed.
[0024] 9 and 10, an inner peripheral edge 70, which is the radially inner edge of the first annular tapered surface 61, is located radially inward of an imaginary circle C1 of the first circlip 51. The inner peripheral edge 70 of the first annular tapered surface 61 is a circle located at the boundary between the first annular tapered surface 61 and the annular flat surface 63. As a result, as shown in the enlarged portion of FIG. 10, even when the piston pin 32 moves in the direction of arrow X1 and comes into contact with the first circlip 51, the inner peripheral edge 70 of the first annular tapered surface 61 can be brought into contact radially inward of the imaginary circle C1, which is the cross-sectional center of the clip body 53.
[0025] In other words, the piston pin 32 contacting the first circlip 51 expands the clip body 53 of the first circlip 51 radially outward as shown by the arrow X2, preventing the first circlip 51 from coming off the first clip groove 41b. In other words, the first circlip 51 is pressed into the first clip groove 41b, preventing the first circlip 51 from coming off the first clip groove 41b. Note that even when the other end 32b of the piston pin 32 contacts the second circlip 52, the clip body 53 of the second circlip 52 can be expanded radially outward in the same way, preventing the second circlip 52 from coming off the second clip groove 42b.
[0026] 9 and 10, the side surfaces 54a, 55a of the bent end portions 54, 55 of the first circlip 51 face the second annular tapered surface 62 of the piston pin 32. Here, as shown in FIG. 7, the angle A2 formed between the outer peripheral surface 60 of the piston pin 32 and the second annular tapered surface 62 is set to an acute angle. As a result, even when the piston pin 32 comes into contact with the first circlip 51, the second annular tapered surface 62 of the piston pin 32 can be separated from the bent end portions 54, 55 of the first circlip 51. In other words, interference between the bent end portions 54, 55 and the second annular tapered surface 62 can be avoided, thereby preventing the first circlip 51 from falling off due to interference with the bent end portions 54, 55. Furthermore, as shown in FIG. 11, even when the bent end portion 54 of the first circlip 51 is deformed and tilted toward the piston pin 32, interference between the bent end portion 54 and the second annular tapered surface 62 can be avoided or reduced. This makes it possible to prevent the first circlip 51 from falling off due to interference with the deformed bent end portion 54. Even when the other end portion 32b of the piston pin 32 comes into contact with the second circlip 52, it is possible to similarly avoid or reduce interference between the bent end portions 54, 55 and the second annular tapered surface 62, and to prevent the second circlip 52 from coming off the second clip groove 42b.
[0027] As described above, by forming the first annular tapered surface 61 and the second annular tapered surface 62 on both the one end 32a and the other end 32b of the piston pin 32, it is possible to prevent the circlips 51, 52 from coming off due to contact with the piston pin 32. Furthermore, even when the first and second annular tapered surfaces 61, 62 are formed on the piston pin 32, an annular flat surface 63 is formed between the first annular tapered surface 61 and the second annular tapered surface 62. In this way, by providing the annular flat surfaces 63 on both the one end 32a and the other end 32b of the piston pin 32, it becomes easy to control the length dimension of the piston pin 32. Note that the annular flat surface 63 is an annular flat surface having a width dimension of, for example, several tens to several hundreds of micrometers. Furthermore, the angle A1 formed between the first annular tapered surface 61 and the second annular tapered surface 62 is an obtuse angle, and the angle A2 formed between the outer circumferential surface 60 and the second annular tapered surface 62 is an acute angle. This allows the second annular tapered surface 62 to be separated from the circlips 51, 52, thereby avoiding excessive interference between the piston pin 32 and the circlips 51, 52. Furthermore, since the second annular tapered surface 62 is not excessively inclined with respect to the center line CL, piston pin information such as the part number 64 can be appropriately engraved on the second annular tapered surface 62.
[0028] The present invention is not limited to the above-described embodiment, and various modifications are possible without departing from the spirit and scope of the present invention. For example, in the example shown in FIG. 8, a pair of bent end portions 54, 55 are formed on the circlips 51, 52. However, this is not limited thereto. The bent end portion 54 may be formed on only one end of the clip body 53. In other words, only one bent end portion 54 may be formed on the circlips 51, 52. Furthermore, in the example shown in FIG. 8, the bent end portions 54, 55 of the circlips 51, 52 are crushed to be thin, but this is not limited thereto. The bent end portions 54, 55 may be formed without being crushed. In other words, the cross-sectional shapes of the clip body 53 and the bent end portions 54, 55 may be made to match each other. Furthermore, in the example shown in FIG. 8, the cross-sectional shape of the clip body 53 is formed to be circular, but this is not limited thereto. The cross-sectional shape of the clip body 53 may be formed to be rectangular. [Explanation of symbols]
[0029] 20 Piston connection structure 31 Piston 32 Piston pin 32a One end 32b Other end 33 Connecting rod 34 Small end 41b First clip groove 42b Second clip groove 43 Pin boss part 51 First circlip 52 Second circlip 53a wire rod 54,55 Bent end 54a,55a Side 60 Outer surface 61 First annular tapered surface 62 Second annular tapered surface 63 Circular flat surface 64 Part number (piston pin information) 70 inner periphery CL center line A1 angle A2 angle C1 Virtual circle
Claims
1. A piston connection structure that connects a piston to a connecting rod, a piston pin inserted into both a pin boss portion formed on the piston and a small end portion formed on the connecting rod; a first circlip attached to a first clip groove formed in the pin boss portion and adjacent to one end of the piston pin; a second circlip attached to a second clip groove formed in the pin boss portion and adjacent to the other end of the piston pin; and At both the one end and the other end of the piston pin, a first annular tapered surface extending radially inward from an outer peripheral surface of the piston pin and inclined relative to a center line of the piston pin; a second annular tapered surface disposed radially inward of the first annular tapered surface and inclined relative to the center line; is formed, an angle formed between the first annular tapered surface and the second annular tapered surface is an obtuse angle; The angle formed between the outer peripheral surface and the second annular tapered surface is an acute angle. Piston linked structure.
2. The piston connecting structure according to claim 1, an annular flat surface perpendicular to the center line is formed between the first annular tapered surface and the second annular tapered surface; Piston linked structure.
3. The piston connecting structure according to claim 1 or 2, an inner peripheral edge of the first annular tapered surface is located radially inward of an imaginary circle passing through centers of wire rods constituting the first and second circlips, the imaginary circle passing through the centers of wire rods constituting the first and second circlips; Piston linked structure.
4. The piston connecting structure according to any one of claims 1 to 3, the first and second circlips have bent ends that are bent inward; a side surface of the bent end portion facing the second annular tapered surface; Piston linked structure.
5. The piston connecting structure according to any one of claims 1 to 4, Piston pin information is marked on the second annular tapered surface. Piston linked structure.
Citation Information
Patent Citations
JP1976094360U
JP1979147876U
JP1981138135U
Ceramic piston pin
JP1988004465U
JP1990102072U