JP2006177459A - Lubricating structure of crankshaft sliding bearing - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To prevent a crankshaft from being worn or seized by securely holding a lubricating oil on sliding bearings supporting the crankshaft to increase the lubricity of the sliding bearings when an engine is started. <P>SOLUTION: An oil seal 34 for preventing the lubricating oil from leaking is fitted to the case body 10a of a crankcase 11 supporting the crankshaft 10, and the sliding bearings 31 having fitting holes 32 for fitting them to the crankshaft 10 are fitted to the case body of the crankcase. Supply grooves 35 for supplying the lubricating oil between the journal part and the fitting hole 32 of the crankshaft 10 is formed in the sliding bearings 31, and return grooves 38 communicating with the fitting holes 32 at a higher position than the bottom area 37 of the fitting hole 32 are formed therein. An oil sump 39 is formed between the inner end face of the oil seal 34 and the sliding bearings 31. The lubricating oil is retained in the oil sump 39 and the bottom area 37. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a lubrication structure for a crankshaft slide bearing that rotatably supports a crankshaft incorporated in an engine crankcase.

  The engine has a crankshaft that is rotated by a reciprocating motion of a piston, and the crankshaft is rotatably mounted in a crankcase. Lubricating oil is contained in the crankcase of a four-cycle engine, and the lubricating oil slides between the bearing of the crankshaft incorporated in the crankcase, the connecting portion between the crankshaft and the connecting rod, and between the piston and the cylinder bore. To be supplied to the department. The crankshaft of a general-purpose engine used to drive a generator, a sprayer, etc., scrapes up the lubricating oil in the crankcase and supplies the lubricating oil to the sliding part, that is, the lubricating oil demanding part. Etc. are attached.

Conventionally, a crankcase of a general-purpose engine is mounted with a rolling bearing such as a ball bearing or a needle bearing to support the crankshaft, and the lubricant that has passed through the ball bearing or the like is outside the ball bearing. An oil seal is attached to prevent leakage to the outside. Patent Document 1 describes a technique in which lubricating oil that has passed through a rolling bearing is returned to an oil pan of a crankcase.
JP-A-10-299447

  If the crankshaft is supported by a metal bearing, that is, a sliding bearing, without attaching the rolling bearing to support the crankshaft to the crankcase, the assembly process of the rolling bearing to the crankcase is not required, and the engine manufacturing cost Therefore, an attempt was made to attach the crankshaft directly to the crankcase. However, if a sliding bearing is provided in the crankcase so as to directly support the crankshaft, an oil film of the lubricating oil is surely formed on these sliding portions unless sufficient lubricating oil is supplied between the crankshaft and the sliding bearing. Can not be formed. Therefore, a groove is formed in the upper part of the sliding bearing to supply lubricating oil to the sliding surface of the sliding bearing, and an oil return hole is formed in the crankcase so that the lubricating oil is returned from the oil seal side into the crankcase. However, with this structure, it was not possible to ensure sufficient retention of the lubricating oil between the sliding surfaces. For example, when the engine has been stored for a long time, the oil film is not held between the sliding surfaces, and the crankshaft and the slide bearing are in a state close to dry contact, so the stored engine was started. Sometimes, the crankshaft and the sliding bearing may be in direct contact with each other, and the sliding portion may be worn, and in some cases, the crankshaft may be damaged or seized.

  An object of the present invention is to ensure that lubricating oil can be reliably held in a sliding bearing that supports a crankshaft.

  Another object of the present invention is to improve the lubricity of the sliding bearing when the engine is started to prevent the crankshaft from being worn or seized.

  The lubrication structure for a crankshaft slide bearing according to the present invention is provided in a crankcase that supports a crankshaft so as to be positioned inside an oil seal that prevents leakage of lubricant contained in the crankcase. A lubrication structure of a crankshaft slide bearing that lubricates a slide bearing having a fitting hole that fits into the oil seal, wherein an oil sump is formed between the inner end surface of the oil seal and the slide bearing, and the inner end portion is a crank chamber. And a supply flow path for supplying lubricating oil between the journal portion of the crankshaft and the fitting hole into which the journal portion is fitted. Is formed in the sliding bearing, communicates with the fitting hole at a position higher than the bottom region of the fitting hole, and forms a return passage in the sliding bearing for returning the lubricating oil into the crankcase. And it features.

  In the lubricating structure of the crankshaft slide bearing of the present invention, the supply flow path is formed by a supply groove extending in the axial direction of the fitting hole and opening in the inner peripheral surface of the fitting hole, and the axial direction of the fitting hole The return flow path is formed by a return groove that extends in the opening and opens in the inner peripheral surface of the fitting hole.

  The lubrication structure for a crankshaft slide bearing according to the present invention is characterized in that the return flow path is formed by a through-hole extending in parallel with the axial direction of the fitting hole and opening in an end face of the oil seal and in the crankcase. And

  The lubrication structure for a crankshaft slide bearing according to the present invention is characterized in that an oil retaining material made of a porous material is provided in the return channel.

  According to the present invention, the lubricating oil stored in the crankcase is supplied from the supply flow path between the journal portion of the crankshaft and the inner peripheral surface of the fitting hole into which the crankshaft is fitted to lubricate the slide bearing. Is called. Since the lubricating oil supplied between them and the lubricating oil supplied to the oil sump between the oil seal and the slide bearing are returned to the crankcase from the return passage located higher than the bottom region of the fitting hole, The lubricating oil is retained in the bottom region. As a result, even if the engine is stored for a long period of time, the lubricating oil is securely held in the sliding bearing, so that the crankshaft and the sliding bearing are prevented from being worn when the engine is started, and the crankshaft Occurrence of galling and image sticking is prevented.

  If the supply flow path and the return flow path are each formed by a groove, the groove can be formed at the time of casting the crankcase, and there is no need to form the flow path by post-processing. By providing an oil retaining material that is impregnated with lubricating oil in the return channel, it is possible to prevent oil shortage in the sliding bearing for a longer period of time.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic view showing a general-purpose engine having a lubricating structure of the present invention, FIG. 2 is a partially cutaway front view showing the inner surface of the crankcase shown in FIG. 1, and FIG. 3 is shown in FIG. FIG. 4A is a cross-sectional view of FIG. 3 and FIG. 4B is a front view in the direction of arrow B in FIG. 4A.

  As shown in FIG. 1, this general-purpose engine has a crankcase 11 on which a crankshaft 10 is rotatably mounted. The crankcase 11 is composed of a case body 11a and a case cover 11b attached to the case body 11a. The crankcase 11 is provided with a cylinder 12. A piston 14 is incorporated in a cylinder bore 13 of the cylinder 12 so as to be reciprocally movable. The piston 14 is connected to the crankshaft 10 via a connecting rod 15. As shown in FIG. 2, the piston 14 reciprocates at an inclination angle of an angle θ with respect to the case horizontal line H in a state where the crankcase 11 is disposed on a horizontal plane. This angle θ is about 25 degrees in the illustrated case. This engine is a single-cylinder four-cycle gasoline engine, and an engine body 17 is formed by a cylinder head 16, a crankcase 11, and a cylinder 12 attached to the cylinder 12.

  As shown in FIG. 1, a recoil pulley 18 is rotatably mounted on the crankshaft 10 as shown in FIG. 1, and a recoil rope 19 having a recoil knob 19 a at its tip is wound around the recoil pulley 18. It has been. Therefore, when the recoil rope 19 is pulled out and the recoil pulley 18 is rotated, the crankshaft 10 is driven manually and the engine can be started.

  When the generator is driven using this general-purpose engine, the generator is incorporated in the crankshaft 10, and when the power sprayer is driven, the shaft of the sprayer is connected to the crankshaft 10. Become. A cooling fan 20 for generating cooling air toward the engine body 17 is attached to the crankshaft 10.

  The cylinder head 16 is driven by an intake valve for opening and closing an intake port for supplying an air-fuel mixture to the combustion chamber 21 in the cylinder 12 and an exhaust port for discharging combustion exhaust gas in the combustion chamber 21 to the outside. Exhaust valves are provided. In order to drive these intake and exhaust valves, a sprocket 23 is fixed to a camshaft 22 rotatably mounted on the engine body 17 as shown in FIG. A chain 25 is stretched between the sprocket 24 and the sprocket 23 that are fixed to each other. Therefore, when the engine is driven and the crankshaft 10 rotates, the camshaft 22 is rotationally driven in synchronization with the rotation of the crankshaft 10. The bottom part of the crank chamber 26 formed inside the crankcase 11 is an oil pan, in which the lubricating oil 27 is accommodated, and the lubricating oil 27 splashes on a sliding part as a lubrication required part. In addition, as shown in FIGS. 1 and 2, a scraper 28 is provided on the cap 15 a of the connecting rod 15. The lubricating oil 27 scraped up by the scraper 28 is supplied by being splashed against a sliding portion of a member incorporated in the crankcase, and the sliding portion comes into contact via an oil film of the lubricating oil. .

  As shown in FIG. 1, one end of the crankshaft 10 is supported by the case body 11a, and the other end is supported by the case cover 11b. Both ends of the crankshaft 10 are connected to the case body 11a and the case cover 11b. Each of the through holes is formed so as to protrude outside. As shown in FIGS. 2 to 4, the case body 11 a is provided with a slide bearing 31, and the slide bearing 31 has a fitting hole 32 that fits into a journal portion on one end side of the crankshaft 10. ing. The case body 11a is positioned outside the fitting hole 32 and has a mounting hole 33 having a diameter larger than that of the fitting hole 32, and an oil seal 34 is attached to the mounting hole 33. . The oil seal 34 prevents the lubricating oil 27 in the crankcase 11 from leaking outside.

  In the illustrated case, the sliding bearing 31 is integrally formed of the same metal material as the case main body 11a. However, the bearing sleeve is press-fitted or cast into the case main body 11a, and the bearing sleeve is inserted into the case main body 11a. It is also possible to integrate them.

  A supply groove 35 extending in the axial direction of the fitting hole 32 is formed in the upper part of the sliding bearing 31 so as to communicate with the inner peripheral surface of the fitting hole 32 over the entire length of the fitting hole 32. The inner end portion of the crankshaft 26 opens to the crank chamber 26, and the outer end portion faces the oil seal 34, and the lubricating oil 27 is supplied between the journal portion of the crankshaft 10 and the fitting hole 32 by the supply groove 35. A supply flow path is configured. In order to guide the lubricating oil 27 in the crank chamber 26 to the supply groove 35, a guide groove 36 communicating with the supply groove 35 is formed on the inner surface of the case body 11a. Accordingly, the lubricating oil 27 supplied into the supply groove 35 enters between the fitting hole 32 and the journal portion and reaches a part of the inner end face of the oil seal 34 as indicated by an arrow.

  A lower portion of the fitting hole 32 is a bottom region 37, and a return groove 38 communicating with the fitting hole 32 at a position higher than the bottom region 37 extends in the axial direction of the fitting hole 32. It is formed over the entire length. The inner end of the return groove 38 opens into the crank chamber 26, and the outer end faces the oil seal 34, and the lubricating oil 27 reaching the oil seal 34 is returned to the crank chamber 26 by the return groove 38. A flow path is configured. Since the return groove 38 constituting the return flow path is offset above the bottom region 37, an oil reservoir 39 is formed between the inner end face of the oil seal 34 and the slide bearing 31. A predetermined amount of lubricating oil 27 is stored in the bottom region 37. The lubricating oil 27 is sufficiently retained in the bottom region 37, and the lubricating oil 27 is retained in the bottom region 37 even when the engine is stopped. The journal part is immersed in the lubricating oil 27. The oil reservoir 39 is indicated by a dot in FIG.

  Thus, since the lubricating oil 27 is stored in the oil reservoir 39 and the bottom region 37, the oil reservoir 39 and the bottom region 37 are maintained even if the engine is started after being held for a long time without being used. The lubricating oil 27 held in the gap enters between the journal portion and the fitting hole 32, and the sliding bearing 31 is lubricated. In addition, when the crankcase 11 is formed by casting, a supply flow path is formed by the supply groove 35 and a return flow path is formed by the return groove 38, so that the grooves 35 and 38 are simultaneously formed at the time of casting. And post-processing using a drill becomes unnecessary.

  When the engine is rotating, the combustion pressure of the piston 14 is applied to the slide bearing 31 from the journal portion, and the range of an angle α of about 180 degrees facing the piston 14 on the inner peripheral surface of the fitting hole 32. However, since the supply groove 35 and the return groove 38 are not formed in the region to be the pressure receiving surface, the bearing surface pressure and strength of the sliding bearing 31 are ensured.

  2 to 4 show the sliding bearing 31 provided on the case main body 11a, the sliding bearing 31 having the same structure is also provided on the case cover 11b, and an oil seal 34 is mounted.

  FIG. 5 (A) is a cross-sectional view showing a lubricating structure according to another embodiment of the present invention, and FIG. 5 (B) is a front view in the direction of arrow B in FIG. 5 (A). ) Shows a portion corresponding to FIG. 4A of the crankcase 11, and FIG. 5B shows a portion corresponding to FIG. 4B.

  In the case shown in FIG. 5, in the above-described case, the return channel is formed by the return groove 38, whereas the return channel is formed by the through hole 41. The through hole 41 is formed in the sliding bearing 31 so as to extend in parallel with the fitting hole 32, and has an inner end opening into the crank chamber 26 and an outer end facing the oil seal 34. As shown in FIG. 5B, an oil retaining material 42 made of a porous material is incorporated in the through hole 41, and the lubricating oil 27 is retained in the through hole 41. As the porous material constituting the oil retaining material 42, sponge, felt, or sintered body is used. When the oil retaining material 42 is incorporated into the return channel in this way, the function of supplying the lubricating oil into the fitting hole 32 is enhanced. Furthermore, a similar oil retaining material 42 may be incorporated in the oil sump 39.

  However, the oil retaining material 42 may not be incorporated in the through hole 41, and the oil retaining material 42 may be incorporated in the return groove 38 shown in FIGS. Further, in each of the above-described embodiments, a through hole is formed in the slide bearing 31 in the same manner as the through hole 41 instead of the supply groove 35, and the lubricating oil 27 is supplied from the end surface side of the oil seal 34 to the inner periphery of the fitting hole 32. You may make it supply between a surface and a journal part. Moreover, you may make it apply the sliding bearing 31 of the structure shown in FIG. 5 to the case cover 11b.

  The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the scope of the invention.

It is the schematic which shows the general purpose engine which has the lubrication structure of this invention. It is a partially cutaway front view which shows the inner surface of the crankcase shown by FIG. It is a perspective view which expands and shows the sliding bearing shown by FIG. (A) is sectional drawing of FIG. 3, (B) is a front view of the arrow B direction in (A). (A) is sectional drawing which shows the lubricating structure which is other embodiment of this invention, (B) is a front view of the arrow B direction in (A).

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Crankshaft 11 Crankcase 31 Sliding bearing 32 Fitting hole 34 Oil seal 35 Supply groove (supply flow path)
37 bottom region 38 return groove (return channel)
39 Oil sump 41 Through hole (return channel)
42 Oil retaining material

Claims (4)

A sliding bearing having a fitting hole that is provided in a crankcase that supports the crankshaft and is positioned inside an oil seal that prevents leakage of lubricating oil contained in the crankcase and that fits into the crankshaft. A lubricating structure of a crankshaft sliding bearing to be lubricated,
Forming an oil sump between the inner end face of the oil seal and the sliding bearing;
Lubricating oil is provided between the journal portion of the crankshaft and the fitting hole into which the journal portion is fitted, the inner end portion being open to the crank chamber and the outer end portion being opposed to the oil seal and communicating with the oil reservoir. Forming a supply flow path in the sliding bearing,
A crankshaft slide bearing comprising: a slide passage formed in the slide bearing that communicates with the fit hole at a position higher than a bottom region of the fit hole and returns the lubricating oil into the crankcase. Lubrication structure.   2. The lubrication structure for a crankshaft slide bearing according to claim 1, wherein the supply flow path is formed by a supply groove extending in an axial direction of the fitting hole and opening on an inner peripheral surface of the fitting hole, A lubrication structure for a crankshaft slide bearing, wherein the return flow path is formed by a return groove extending in an axial direction and opening on an inner peripheral surface of the fitting hole.   2. The lubrication structure for a crankshaft sliding bearing according to claim 1, wherein the return flow path is formed by a through-hole extending in parallel with the axial direction of the fitting hole and opening in an end face of the oil seal and in the crankcase. Crankshaft sliding bearing lubrication structure characterized by   4. The lubrication structure for a crankshaft slide bearing according to any one of claims 1 to 3, wherein an oil retaining material made of a porous material is provided in the return channel.

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