GB2431701A

GB2431701A - Lubrication of a one way clutch in a transmission mechanism

Info

Publication number: GB2431701A
Application number: GB0618066A
Authority: GB
Inventors: Masaki Yoneyama; Hisao Otsuka
Original assignee: Honda Motor Co Ltd
Current assignee: Honda Motor Co Ltd
Priority date: 2005-10-25
Filing date: 2006-09-13
Publication date: 2007-05-02
Anticipated expiration: 2026-09-13
Also published as: JP4236656B2; GB2431701B; DE102006044876A1; GB0618066D0; JP2007120307A; DE102006044876B4

Abstract

A transmission mechanism for a starter motor in an internal combustion engine, comprises a thrust pad 51 disposed closer to a main bearing 6 of a crankshaft 4 than a one-way clutch C, and includes oil holes 52, located in the same position in the radial direction as the bearing 51, for allowing lubricating oil that has flowed out of the main bearing 6 and scattered to flow in the oil holes 52 and then to flow out thereof toward the bearing 51. The one-way clutch C includes a radial direction oil passage 62 for deflecting the lubricating oil which has flowed in from the oil holes 52 and passed through while lubricating a roller bearing 41, outward in the radial direction and thereby guiding the lubricating oil to a housing space 34 in which sprags 33 are housed. A discharge oil passage 39 located in the same position in the radial direction as outer portions 33a of the sprags 33, for discharging the lubricating oil in the housing space 34. Thus lubrication of a bearing 51 and a one-way clutch C is improved by facilitating oil supply to the bearing 51.

Description

Transmission Mechanism Including One-Way Clutch The present invention

relates to a transmission mechanism including a one-way clutch, and more specifically to a lubrication structure in the transmission mechanism. Moreover, the transmission mechanism is used as a transmission mechanism for rotationally driving a crankshaft when starting an internal combustion engine, for example.

A known lubrication structure in a transmission mechanism of this type is disclosed, for example, in Japanese Unexamined Patent Publication No. 2000 -161037 (Fig. 13). In this conventional technique, a feed hole for feeding lubricating oil supplied to a bearing for supporting a crankshaft into an overrunning clutch is provided on an output member that rotates integrally with an outer ring of the clutch.

In the above-described conventional technique, sihce the feed hole is located in the same position in the radial direction as an inner ring of the clutch, the lubricating oil is not supplied directly from the feed hole to the bearing (a roller bearing), which is disposed between the crankshaft and the inner ring of the clutch and is located more inward than the feed whole in the radial direction, and the lubricating oil that flows therein from the feed hole and is attached to the inner ring of the clutch flows outward in the radial direction due to a centrifugal force. Accordingly, in the above structure, it is difficult to supply the lubricating oil to the bearing. For this reason, in order to ensure required durability of the bearing even in the case of using a relatively small amount of the lubricating oil, it has been necessary to use an expensive substance for the material of the bearing.

The present invention has been made in view of the foregoing circumstance. An object of at least the preferred embodiments of the present invention is to improve lubrication of a bearing and a one-way clutch respectively by facilitating oil supply to the bearings.

According to a first aspect of the invention, there is provided a transmission mechanism including a one-way clutch having a clutch element, which is disposed between an inner race and an outer race in a radial direction, and which is configured to perform transmission of rotation only from one of the inner race and the outer race to the other; a bearing, which is disposed between the inner race and a rotating shaft in the radial direction, and which is configured to * rotatably support the inner race on the rotating shaft; and a regulating member for regulating movement of the one-way clutch in the axial direction. Here, the regulating member, on which the one-way clutch abuts in the axial direction, is provided with oil holes in the same position in the radial direction as the bearing, and allows lubricating oil scattering in an atmosphere surrounding the regulating member to flow in and then to flow out toward the bearing The one-way clutch is provided with a radial direction oil passage for deflecting the lubricating oil, which has flowed therein from the oil holes, and which then has passed through the bearing while lubricating the bearing, outward in the radial direction and for thus guiding the lubricating oil to a housing space where the clutch element is housed; and a discharge oil passage for discharging the lubricating oil in the housing space, the discharge oil passage being located in the same position in the radial direction as an outer portion of the clutch element in the radial direction or a position more outward in the radial direction than the clutch element.

According to this aspect, since the oil holes are located in the same position in the radial direction as the bearing, the lubricating oil that has flowed into the oil holes is easily guided to the bearing and the oil supply to the bearing is thus facilitated. The lubricating oil that has lubricated the bearing is pressurized by a centrifugal force in the radial direction oil passage in the one-way clutch, and then lubricates the clutch element in the housing space. The lubricating oil in the housing space sufficiently lubricates the clutch element from the inner race side toward the outer race side in the housing space before being discharged out of the one-way clutch from the outer portion of the clutch element or from the portion more outward in the radial direction than the clutch element.

Specifically, by the series of oil passages * extending from the oil holes to the housing space through the bearing and the radial direction oil passage, the bearing is lubricated with a sufficient oil amount of the lubricating oil from the oil holes located in the same position in the radial direction as the bearing. Accordingly, lubrication thereof is improved and durability of the bearing is ensured at low costs without using an expensive material. Moreover, since the clutch element is sufficiently lubricated by the lubricating oil pressurized by the centrifugal force before being discharged from the outer portion of the clutch element or the portion more outward in the radial direction than the clutch element to an outer space of the one-way clutch, the lubrication of the one-way clutch is improved.

According to a second aspect of the present invention, there is provided a transmission mechanism for an internal combustion engine including a one-way clutch having a clutch element, which is disposed between an inner race and an outer race of the one-way clutch in the radial direction, and which is configured to perform only transmission of rotation from a starter motor to a crankshaft from one of the inner race and the outer race to the other, a bearing, which is disposed between the inner race and the crankshaft in the radial direction, and which is configured to rotatably support the inner race on the crankshaft, and a regulating member, which regulates movement of the one-way clutch in an axial direction. Here, the regulating member which is disposed closer to a main bearing of the crankshaft in the axial direction than the one-way clutch, is provided with oil holes located in the same position in the radial direction as the bearing, and the regulating member allows lubricating oil that has flowed out of the main bearing and has scattered in an atmosphere surrounding the regulating member to flow in and then to flow out toward the bearing, and the one-way clutch is provided with a radial direction oil passage for deflecting the lubricating oil, which has flowed in from the oil holes and passes through the bearing while lubricating the bearing, outward in the radial direction, and thereby to guide the lubricating oil to a housing space where the clutch element is housed, and a discharge oil passage, which is located in the same position in the radial direction as an outer portion of the clutch element in the radial direction or a position more outward in the radial direction than the clutch element, for discharging the lubricating oil in the housing space.

According to this aspect, in the internal combustion engine, operation similar to the first aspect of the invention is achieved in the transmission inechanisni including the one-way clutch for transmitting the rotation from the starter motor to the crankshaft, and an effect similar to that described above in the context of the first aspect is achieved in the * transmission mechanism including the one-way clutch for transmitting rotation from the starter motor to the * 20 crankshaft.

* preferably, the transmission mechanism is provided with a sprocket, on which an endless chain is wound, between the main bearing and the regulating member in the axial direction, and any of a chain tensioner and a chain guide to which the chain slideably contacts is disposed on an opposing surface facing the chain in an overlapping position with the regulating member in the direction along the opposing surface when viewed in the axial direction.

Thus, the scatter of the lubricating oil flowed out of the main bearing and the lubricating oil scattered from the chain outward in the radial direction are p. suppressed by the chain tensioner or the chain guide in the vicinity of the regulating member, and accordingly, the amount of flow of the scattered lubricating oil into the oil holes is increased.

Further, since the amount of the lubricating oil flowing in from the oil holes is increased, the lubrication of the bearing and the one- way clutch are further improved.

Preferred embodiments of the invention will now be described by way of example only with reference to Figs. 1 to 4, in which: Fig. 1 is a side view of a transmission mechanism in an internal combustion engine, to which the present invention is applied, and which is a view taken along the I-I arrow in Fig. 2; Fig. 2 is a cross-sectional view taken along the 11-11 line in Fig. 1; Fig. 3 is a cross-sectional view taken along the 111-111 line in Fig. 1; and Fig. 4 is a cross-sectional view taken along the IVa-IVa line in Fig. 1 concerning a chain tensioner and a chain guide, and a cross-sectional view taken along IVb-IVb line in Fig. 1 concerning a shaft end of a crankshaft, a one-way clutch, and a driving sprocket.

Referring to Figs. 1 and 2, a preferred embodiment of the transmission mechanism T of the present invention includes a one-way clutch C for performing transmission * of rotation only from a starter motor M to a crankshaft 4 in order to rotationally drive the crankshaft 4 by the starter motor M when starting an internal combustion engine E. The internal combustion engine E to be mounted on a motorcycle as a vehicle is a multicylinder four-stroke internal combustion engine including a cylinder block 1, in which multiple cylinders la (one of which is shown in Fig. 2) are arranged in series, a lower crank case 2b to be joined to a lower end of an upper crank case 2a composed of a lower part of the cylinder block 1, and a cylinder head (not shown) to be joined to an upper end of the cylinder block 1.

The crankshaft 4, which is connected to pistons (not shown) reciprocably fitted in the respective cylinders la via connecting rods 3, is housed in a crank chamber 5 formed of a crank case 2 constructed by joining the upper crank case 2a to the lower crank case 2b, and is rotatably supported by bearing portions 7 of the crank case 2 via main bearings 6 which are bearings made of metal bearings to be sandwiched by the upper crank case 2a and the lower crank case 2b. Lubricating oil ejected from an oil pump driven by power of the crankshaft 4 is suppliedto the respective main bearings 6 severally retained by the multiple bearing portions 7, which are provided in arrangement on the crank case 2 with intervals in the axial direction, through oil passages (not shown) formed on the bearing portions 7.

It is to be noted that the "axial direction", the "radial direction", and a "circumferential direction" as used herein mean a direction parallel to a rotation centre line L of a rotating shaft or the crankshaft 4, a radial direction centring on the rotation centre line L, and a circumferential direction centring on the rotation centre line 1,, respectively.

The cylinder head is provided with an intake valve and an exhaust valve configured to open and close an intake port and an exhaust port that are open to a combustion chamber. The intake valve and the exhaust valve are to be opened and closed synchronously with rotation of the crankshaft 4 by use of a valve train including a cam shaft which is rotatably supported by the cylinder head. The cam shaft is rotationally driven at half the rotating speed of the crankshaft 4 by use of a drive mechanism, which is constituted of a driving sprocket 8 provided on a shaft end 4a of the crankshaft 4, a cam sprocket provided on the cain shaft, an endless chain 9 made of a silent chain wound on those sprockets, a chain tensioner 10 for imparting tension to the chain 9 at a loose side of the chain 9, and a chain guide 11 on which the chain 9 slideably contacts at a strained side of the chain 9.

Referring to Fig. 4 in addition, the chain tensioner 10 pivotally supported by a fitting portion 12 provided on the upper crank case 2a includes a long tensioner iDa which includes an opposing surface lOb facing the chain 9 and allows the chain 9 to slideably contact part of the opposing surface lOb, and a tensioner lifter (not shown) which pressures a rear surface of the tensioner shoe lOa to be pressed against the chain 9. In addition, the chain guide 11 fixed to a fitting portion 13 provided on the upper crank case 2a includes an opposing surface lib facing the chain 9 as well as guides the chain 9 slideably contacting part of the opposing surface lib. Here, the term "to face" means positional relations concerning the respective opposing surfaces lOb and lib, in which normal lines of the opposing surfaces lOb and lib intersect the chain 9 on planes intersecting with the rotation centre line L, and which intersects the opposing surfaces lOb and lib.

* In addition, air-fuel mixture, which has passed through the intake port, and which then has flowed into the combustion chamber, is ignited by a spark plug and is cornbusted, and the pistons driven and reciprocated by pressure of combustion gas rotatably drive the * crankshaft 4. The combustion gas is discharged as exhaust gas to outside from the exhaust port through an exhaust system. The power of the crankshaft 4 is transmitted to a shift clutch 15 and a gear transmission sequentially through a primary deceleration mechanism 15.

Referring to Figs. 1 to 3, on the shaft end 4a penetrating an end bearing portion 7a, which also functions as an end wall of the crank case 2 in the axial direction (see Fig. 2), and protruding from the crank chamber 5 in the axial direction, the driving sprocket 8, an annular thrust pad 51 consisting of thrust washers, and the one-way clutch C for * transmitting rotation of the starter motor M to the crankshaft 4, are provided in this order from the main bearing 6. Movement of the driving sprocket 8, the * 25 thrust pad 51, and the one-way clutch C in one direction along the axial direction (a main bearing direction equivalent to a direction to approach the main bearing 6) is blocked by a boss portion 8a of the driving sprocket 8, the boss portion 8a abutting on a step portion of the crankshaft 4, and movement thereof in the * other direction along the axial direction (a counter main bearing direction equivalent to a direction to recede from the main bearing 6) is blocked by a an outer race 32 of the one-way clutch C, the outer race 32 abutting on a washer 19 which is clamped by a bolt 18 screwed into the crankshaft 4 in the axial direction.

Moreover, the driving sprocket 8, the thrust pad 51, and the one-way clutch C are housed together with the shift clutch 5 in a housing chamber 21 formed of the crank case 2 and a case cover 20 connected to the crank case 2 together with the shift clutch 5.

The transmission mechanism T to be provided on the internal combustion engine E and housed in the housing chaxrther 21 includes the one-way clutch C configured to accept transmission of rotation of the starter motor M, which functions as starting means for rotationally driving the crankshaft 4 as the rotating shaft at start of the internal combustion engine E, via a deceleration mechanism 22, and to then transmit rotation of the starter motor M to the crankshaft 4, a roller bearing 41 * functioning as a bearing and configured to rotatably support an inner race 31 on the crankshaft 4, the roller bearing being disposed between the inner race 31 of the one-way clutch C and the crankshaft 4 in the radial direction, and the thrust pad 51 functioning as a regulating member configured to regulate movement of the one-way clutch C in the axial direction by being disposed closer to the main bearing 6 than the one-way clutch C in the axial direction and by abutting on the one-way clutch C. The one-way clutch C includes a starting driven gear 30 functioning as an input rotor to which rotation of the starter motor M fitted to the upper crank case 2a is inputted via the deceleration mechanism 22, the -11 -cylindrical inner race 31 integrated with the driven gear 30 to be integrally rotatable together with the driven gear 30, a cylindrical outer race 32 disposed outward in the radial direction relative to the inner race 31, multiple sprags 33 housed in a housing space 34 formed between the inner race 31 and the outer race in the radial direction to function as a clutch element for performing only transmission of rotation from the inner race 31 which is one of the inner race 31 and the outer race 32 to the outer race 32 which is the other of the inner race 31 and the outer race 32, and an output rotor integrated with the outer race 32 to be integrally rotatable together with the outer race 32 so as to transmit rotation of the outer race 32 to the crankshaft 4. The housing space 34 is an annular space in the axial direction, which is formed between the driven gear and a flange portion 35a to be described later.

Rotation of a pinion 23 provided on a rotating shaft of the starter motor M is transmitted to the driven gear 30 to be rotatably driven by the starter motor M via the deceleration mechanism 22 that consists of a gear row including a large gear 22a to be engaged with the pinion 23, a small gear 22b provided coaxially and rotated integrally with the large gear 22a, and a large gear 22c to be engaged with the small gear 22b.

Moreover, the driven gear 30 is fixed to an inner peripheral portion of the inner race 31 by welding.

Meanwhile, a portion of the housing space 34 closer to the driven gear 30 in the axial direction is open to the housing chamber 21 through an outflow oil passage 37, which is composed of an aperture of an annular washer 36 functioning as a holding member for holding the sprags * 33 in the axial direction and a clearance between the driven gear 30 and the outer race 32. The lubricating oil in the housing space 34 partially passes through the outflow oil passage and flows out to the housing chamber * 5 21.

The output rotor 35 integrally formed with and provided on the outer race 32 includes the flange * portion 35a which is located on the opposite side to the driven gear 30 and the thrust pad 51 in the axial direction while interposing the sprags 33, and which is formed in a plate shape extending in the radial direction, and an annular shaft portion 35b connected to an inner peripheral portion of the flange portion 35a.

The output rotor 35 is integrally rotatably joined to the crankshaft 4 by spline fitting of an inner periphery of the shaft portion 35b to an outer periphery of the shaft end 4a.

The flange portion 35a is provided with multiple pieces of discharge oil passages 39 located at even * 20 intervals in the circumferential direction, which are formed of penetrating holes, that are open to the * housing chamber 21 in the same positions in the radial direction as outer portions 33a of the sprags 33 in the radial direction, and that thereby communicate the housing space 34 being an internal space of the one-way clutch C and the housing chamber 21 being an external space of the one-way clutch C. In this embodiment, three discharge oil passages are provided. Although each of the discharge oil passages 39 is parallel to the axial direction, the discharge oil passage 39 may be inclined such that an outlet 39b of the discharge oil * passage 39 is located more inward in the radial -13 -direction or more outward in the radial direction than a position of an inlet 39a of the discharge oil passage in the radial direction.

The shaft portion 35b is located in a position SO as to overlap the inner race 31, the outer race 32, and the sprags 33 in the axial direction. Moreover, an end surface at one end portion 35b1 in the axial direction is located on the same plane perpendicular to the rotation centre line L as an end surface at one end 31a in the axial direction of the inner race 31, and abuts on the thrust pad 51 in the axial direction.

The roller bearing 41, which is a rolling bearing, is disposed between an outer periphery of the shaft portion 35b and an inner periphery of the inner race 31 in the radial direction, and consists of numerous needle-shaped rollers 42 functioning as rolling bodies and a holder 43 for holding the rollers 42 in the respective predetermined positions thereof. By the * holder 43, between the rollers 42 which are adjacent to one another in the circumferential direction, an oil passage 44 inside the bearing is formed on the roller * bearing 41. The oil passage 44 inside the bearing extends in the axial direction and is formed of a clearance which is open at both ends 44a and 44b. For this reason, the roller bearing 41 is open in the axial direction at both of the annular ends 44a and 44b which are defined by the inner race 31 and the shaft portion * 35b in a region in which the rollers 42 are disposed.

The thrust pad 51 is disposed between the driving sprocket 8 and both of the inner race 31 of the one-way clutch C and the shaft portion 35b of the output rotor in the axial direction. One end of the thrust pad 51

S

in the axial direction abuts on the boss portion 8a of the driving sprocket 8 which is spline-fitted to the shaft end portion 4a, and the other end thereof in the axial direction abuts on the end portion 35b1, thus regulating movement of the thrust pad 51 in the axial direction.

The thrust pad 51 axially adjacent to one end portion 41a of the roller bearing 41 is provided with multiple oil holes 52, composed of four round holes herein, which are open in the same position in the radial direction as that of the end portion 44a of the oil passage 44 inside the bearing, are provided at intervals even in the circumferential direction so as to also face 44a in the axial direction. The diameter of each of the oil holes 52 penetrating the thrust pad 51 in the axial direction is greater than the width of the end portion 44a in the radial direction, and the end portion 44a is located inward of each of the holes 52.

Moreover, in this embodiment, each of the oil holes 52 constituting an oil feeding passage to the one-way clutch C is parallel to the axial direction.

Accordingly, an inlet 52a and an outlet 52b thereof are located in the same position in the radial direction as the end portion 44a.

Additionally, referring to Fig. 4, the driving sprocket 8 and the chain 9 are located adjacent to the thrust pad 51 and the oil holes 52 in the axial direction. To be more specific, intervals Wi between a gear teeth 8b and both the thrust pad 51 and the oil holes 52 and W2 between the driving sprocket 8 and both the thrust pad 51 and the oil holes 52 in the axial direction are smaller than a width W3 in the axial

I

direction of the chain 9. Moreover, the oil holes 52 are located in the same position in the radial direction as an addendum circle of the driving sprocket 8 and is also located in the same position in the radial direction as a winding portion 9a of the chain 9 engaged with the driving sprocket 8. For this reason, when the driving sprocket 8 is engaged with the chain 9, the lubricating oil pooled in a concave portion 9c of a ring plate 9b constituting the chain 9 is ejected to a periphery of the chain 9 by the gear teeth 8b of the driving sprocket 8, and part of the ejected lubricating oil flows into the oil holes 52.

Moreover, at least any one of the inner race 31 and the thrust pad 51, which are slideably contacting each other, is provided with oil passages 61 formed in the vicinity of the outlets 52b of the oil holes 52 for guiding part of the lubricating oil flowed into the oil holes 52 to a sliding portion between the thrust pad 51 and the inner race 31, thus the sliding portion is lubricated by the lubricating oil in the oil passage 61.

In this embodiment, the oil passages 61 extending in the radial direction consist of grooves formed on the end surface of the one end 31a in the axial direction of the inner race 31, and multiple passages, namely, four passages are provided at even intervals in the circumferential direction.

Ref erring to Figs. 1 and 2, a radial direction oil * passage 62 for guiding the lubricating oil in the oil passage 44 inside the bearing formed on the roller bearing 41 to the housing space 34 is formed on at least any one of the one-way clutch C and the output rotor 35.

In this embodiment, the radial direction oil passages 62 communicating with the end 44b of the oil passage 44 inside the bearing consist of grooves formed on the end surface of the other end 31b in the axial direction of the inner race 31, and multiple radial direction oil passages, namely, four radial direction oil passages are heie provided at even intervals in the circumferential direction. Each of the radial direction oil passages 62 is open to an inner peripheral portion 34a which is a region located inside the housing space 34 in the radial direction.

Moreover, inside the housing chamber 21, part of the lubricating oil flows in the axial direction out of the main bearing 6, to which the lubricating oil ejected from the oil pump is supplied as described above, and scatters in an atmosphere surrounding the thrust pad 51.

The part of the lubricating oil moves toward each of the oil holes 52 together with an air flow moving in the axial direction, and flows out toward the roller bearing 41 after flowing into each of the oil holes 52. The lubricating oil flowed out of the oil holes 52 flows into the oil passage 44 inside the bearing, then passes through the oil passage 44 inside the bearing while lubricating the sliding portion of the roller bearing 41, such as the rollers 42, then the lubricating oil flows Out through the end 44b at the other end in the axial direction of the roller bearing 41 and is deflected outward in the radial direction by the flange portion 35a, then passes through the radial direction oil passages 62 and flows into the housing space 34 inside the one-way clutch C, and lubricates the respective sprags 33. At the radial direction passages 62, the lubricating oil is pressurized by the -17-centrifugal force and thus the flow is enhanced. Then, the lubricating oil flowed in the housing space 34 in from the radial direction passes through the discharge oil passage 39 and is deflected in the axial direction, and is discharged to the housing chamber 21.

Meanwhile, as shown in Fig. 1, between the main bearing 6 and the thrust pad 51 in the axial direction, the tensioner shoe lOa and the chain guide 11 are respectively disposed in the positions to overlap the oil holes 52 of the thrust pad 51 in the directions along the respective opposing surfaces lOb and lib when viewed in the axial direction. To be more precise, the thrust pad 51 overlaps almost half of the tensioner shoe lOa and the chain guide 11 respectively in the direction along both of the items. Therefore, the thrust pad 51 is located in the position sandwiched by the tensioner shoe lOa and the chain guide 11 in the radial direction thereof.

For this reason, concerning the lubricating oil adhered to the chain 9 and then scattered by the centrifugal force or the lubricating oil flowed out of the main bearing 6 in the axial direction and then scattered by rotation of the crankshaft 4, since the opposing surface lOb of the tensioner shoe lOa and the opposing surface lib of the chain guide 11, which are located close to the thrust pad 51 in the axial direction and also located slightly more outward in the radial direction than the thrust pad 51 function as wall surfaces for preventing the lubricating oil from scattering outward in the radial direction, both of the opposing surfaces lOb and lib suppress the scattering of the lubricating oil outward in the radial direction.

Accordingly, the scattered lubricating oil moves toward the thrust pad51 together with the air flow heading to the thrust pad 51 in the axial direction, and thus an amount of the lubricating oil flowing in from the oil holes 52 is increased.

Next, operations and effects of the embodiment configured as described above will be explained.

In the transmission mechanism T of the internal combustion engine E, the thrust pad 51 is provided with the oil holes 52 located in the same position in the radial direction as the roller bearing 41 for allowing the lubricating oil, which has flowed in the transmission mechanism T after flowing out of the main bearing 6 and scattering, to flow out toward the roller bearing 41. The one-way clutch C is provided with the * radial direction oil passage 62 and the discharge oil passage 39. The lubricating oil flows in from the oil holes 52, passes through the oil passage 44 inside the * bearing while lubricating the roller bearing 41, and then passes over the roller bearing 41. The lubricating oil is deflected outward in the radial direction, and is then guided to the housing space 34 housing the sprags 33 by the radial direction oil passage 62. The discharge oil passage 39 discharges the lubricating oil in the housing space 34. Accordingly, since the oil holes 52 are located in the same position in the radial direction as the bearing, the lubricating oil flowed * into the oil hole 52 is easily guided to the roller bearing 41, thus the oil supply to the roller bearing 41 is facilitated. Moreover, the lubricating oil, which has lubricated the roller bearing 41, is pressurized by the centrifugal force in the radial direction oil passage 62 in the one-way clutch C and the lubricating oil lubricates the sprags 33 in the housing space 34.

The lubricating oil in the housing space 34 sufficiently lubricates the sprags 33 in the housing space 34 from the end of the inner race 31 toward the end of the outer race 32 before being discharged out of the one-way clutch C through the discharge oil passage 39. As a result, by providing the series of oil passages extending from the oil holes 52 to the housing space 34 through the roller bearing 41 and the radial direction oil passage 62, the roller bearing 41 is lubricated with a sufficient amount of the lubricating oil ejected from the oil holes 52 located in the same position in the radial direction as the roller bearing 41. Accordingly, a lubrication is improved and durability of the bearing is ensured at low costs without using an expensive material. Moreover, since the sprags 33 are * sufficiently lubricated by the lubricating oil pressurized by the centrifugal force before the lubricating oil is discharged to the housing chaiber 21 from positions same in the radial direction as the respective outer portions 33a of the sprags 33.

Accordingly, the lubrication of the one-way clutch C is improved.

Since the driving sprocket 8, around which is wound the chain, is provided between the main bearing 6 and the thrust pad 51 in the axial direction and the opposing surface lOb of the chain tensioner 10 and the opposing surface lib of the chain guide.11, which are facing each other, are disposed in positions by overlapping the thrust pad 51 and the oil holes 52 in the directions along the opposing surfaces lOb and llb -20 -when viewed in the axial direction, the scatter of the lubricating oil flowed out of the main bearing 6 and the lubricating oil scattered from the chain 9 outward in the radial direction is suppressed in the vicinity of the thrust pad 51 by the chain tensioner 10 or the chain guide 11. Accordingly, the amount of the lubricating oil flowing in the oil holes 52 after scattering in the one-way clutch is increased. Therefore, the lubrication of the roller bearing 41 and the one-way clutch C are further increased. Moreover, both of the opposing surfaces lOb and lib in the positions where the thrust pad 51 is sandwiched by the surfaces lOb and 10 are disposed in the positions overlapping the oil holes 52 when viewed in the axial direction, the scattered lubricating oil is more apt to flow into the oil holes 52.

The oil holes 52 are located in the same position * in the radial direction as the winding portion 9a of the chain 9 engaged with the driving sprocket 8.

Accordingly, when the driving sprocket 8 is intermeshed with the chain 9, the lubricating oil pooled in the concave portion 9c of the ring plate 9b is emitted to an area surrounding the chain 9 by the gear teeth 8b of the driving sprocket 8 and part of the emitted lubricating oil flows into the oil holes 52. Therefore, the amount of oil supply to the roller bearing 41 is increased.

Regarding other embodiments in which part of the configuration of the above-described embodiment is modified, the modified configurations will be explained below.

The discharge oil passage 39 may be located more outward in the radial direction than the sprags 33 in the flange portion 35a. Furthermore, the discharge oil passage 39 may be provided on the outer race 32.

Moreover, the discharge oil passage 39 may be open to the housing chamber 21 at the out side thereof in the radial direction, instead in the axial direction.

The radial direction oil passages 62 may be grooves formed on the flange portion 35a facing the inner race 31 or may be grooves formed by both of the inner race 31 and the flange portion 35a.

Either the tensioner shoe lOa or the chain guide 11 may be disposed in a position overlapping the oil holes 52 of the thrust pad 51 in a direction respectively along the opposing surface lOb of the tensioner shoe lOa * or the opposing surface lib of the chain guide 11 when viewed in the axial direction.

Although the oil holes 52 have been set parallel to * the axial direction in the above enibothments, it is also * possible to locate the inlets 52a of the oil holes 52 more inward in the radial direction as the outlets 52b so as to form the oil holes 52 obliquely outward in the radial direction from the inlet 52a to the outlet 52b.

In this case, the lubricating oil inside the oil holes 52 flows into the bearing in the state where the oil is pressurized by the centrifugal force. Accordingly, the lubrication of the bearing is further improved.

The transmission mechanism T is also applicable to a machine other than an internal combustion engine.

Claims

-22 -Claims 1. A transmission mechanism comprising: a one-way clutch

including a clutch element for only performing transmission of rotation from one of an inner race and an outer race to the other, the clutch element being disposed between the inner race and the outer race in a radial direction; a bearing for rotatably supporting the inner race on a rotating shaft, the bearing being disposed between the inner race and the rotating shaft in the radial direction; and a regulating member for regulating positional change of the one-way clutch in a direction of a shaft axis, wherein the regulating member, on which the one-way clutch abuts in the axial direction, includes oil holes * located in the same position in the radial direction as the bearing, the oil holes allowing lubricating oil, which has scattered in an atmosphere surrounding the regulating member, to flow therein and then to flow out thereof toward the bearing, and wherein the one-way clutch includes: a radial * direction oil passage for deflecting the lubricating oil, which has flowed therein from the oil holes, and * which has passed through while lubricating the bearing, outward in the radial direction, and thus guiding the lubricating oil to a housing space where the clutch element is housed; and a discharge oil passage for discharging the lubricating oil in the housing space, the discharge oil passage being located in the same position in the radial direction as an outer portion of -23 -the clutch element or a position more outward in the radial direction than the clutch element.

2. A transmission mechanism for an internal combustion engine comprising: a one-way clutch including a clutch element for performing transmission of rotation, which is to be transmitted from a starter motor to a crankshaft, only from one of an inner race and an outer race to the other, the clutch element being disposed between the inner race and the outer race in a radial direction; a bearing for rotatably supporting the inner race on the crankshaft, the bearing being disposed between the inner race and the crankshaft in the radial direction; and a regulating member for regulating positional change of the one-way clutch in a direction of a shaft axis, wherein the regulating member, which is disposed closer to a main bearing of the crankshaft in the direction of the shaft axis than the one-way clutch, includes: oil holes located in the same position in the radial direction as the bearing, the oil holes allowing lubricating oil, which has flowed in an atmosphere surrounding the regulating member from a main bearing, and which has scattered therein, to flow out of the oil holes toward the bearing, after flowing therein, and and wherein the one-way clutch includes: a radial direction oil passage for deflecting the lubricating oil, which has flowed therein from the oil holes, and which has passed through while lubricating the bearing, outward in the radial direction, and thus guiding the

S -24-

lubricating oil to a housing space where the clutch element is housed; and a discharge oil passage for discharging the lubricating oil in the housing space, the discharge oil passage being located in the same position in the radial direction as an outer portion of the clutch element or a position more outward in the radial direction than the clutch element.

3. The transmission mechanism for the internal combustion engine according to claim 2, further comprising a sprocket, on which an endless chain is wound, disposed between the main bearing and the regulating member in the direction of the shaft axis, wherein any of a chain tensioner and a chain guide, each to which the chain slideably contacts, is disposed around an opposing surface thereof facing the chain in a position overlapping with the regulating member in the direction along the opposing surface when viewed in the direction of the shaft axis.

4. A transmission mechanism substantially as described herein with reference to the accompanying drawings.

5. An internal combustion engine having a transmission mechanism as claimed in claim 4.

6. A vehicle having an internal combustion engine as claimed in claim 5.