|Publication number||US7073648 B2|
|Application number||US 10/949,954|
|Publication date||Jul 11, 2006|
|Filing date||Sep 24, 2004|
|Priority date||Oct 24, 2003|
|Also published as||CA2482218A1, CA2482218C, CN1325815C, CN1609469A, CN2766107Y, DE602004014873D1, EP1526300A2, EP1526300A3, EP1526300B1, US20050087418|
|Publication number||10949954, 949954, US 7073648 B2, US 7073648B2, US-B2-7073648, US7073648 B2, US7073648B2|
|Inventors||Tomoaki Ishikawa, Kazuyoshi Miyahara|
|Original Assignee||Honda Motor Co., Ltd.|
|Export Citation||BiBTeX, EndNote, RefMan|
|Patent Citations (5), Referenced by (2), Classifications (11), Legal Events (5)|
|External Links: USPTO, USPTO Assignment, Espacenet|
The present invention relates to power transmission mechanisms employing a one-way clutch in a drivetrain.
One-way clutches, which transmit power in a fixed direction, are, for example, provided at right and left ends of a drive shaft of a self-propelled walk-behind lawn mower in order to facilitate turning of the lawn mower and allow the lawn mower, when moved with an engine stopped, to be easily pushed and moved by hand (see, e.g., U.S. Pat. No. 4,909,365 and Japanese Patent Laid-Open Publication No. 2001-59531).
First, a freewheel clutch disclosed in U.S. Pat. No. 4,909,365 will be described with reference to
When the drive shaft 101 is rotated, the key 103 is simultaneously rotated, causing the projecting portion 103 b of the key 103 to abut on the hollowed portion 104 a of the friction disc 104. Since the friction disc 104 is in frictional engagement with a housing 106, the projecting portion 103 b of the key 103 is not moved further. Thus, the wedge portion 103 a of the key 103 is cocked, projecting from within the first keyway 105. The engaging portion 103 c of the wedge portion 103 a engages one of a plurality of second keyways 102 a formed in the inner peripheral surface of the pinion 102, thereby ensuring transmission of a driving force of the drive shaft 101 to the pinion 102.
When the drive shaft 101 is not rotated, the wedge portion 103 a of the key 103 is received within the first keyway 105 without being cocked, and the pinion 102 can rotate bidirectionally relative to the drive shaft 101.
The above clutch mechanism 100, however, has a problem that, for producing rotation resistance at the friction disc 104 by a thrust spring 107, it is necessary to reduce variations in friction coefficient between the surface of the housing 106, the opposite surfaces of the friction disc 104 and the surface of the pinion 102, resulting in time-consuming surface treatment of these components.
Second, a power transmission mechanism disclosed in Japanese Patent Laid-Open Publication No. 2001-59531 will be described with reference to
A power transmission mechanism 200 shown in
The above power transmission mechanism 200, however, requires highly accurate formation of the surfaces constituting the cam grooves 202, the outer peripheral surfaces of the pins 203 and the inner peripheral surface of the gear hole 207. Specifically, as shown in
Thus, it is desired to ensure transmission of power without impacts by a simple configuration having no need to set the accuracy of fabricating each component at a high degree.
According to the present invention, there is provided a power transmission mechanism, which comprises: a drive shaft rotatably supported by housings, at least one end portion of the drive shaft projecting from the corresponding housing; and a driven member mounted on the projecting one end portion of the drive shaft with a one-way clutch interposed therebetween; the one-way clutch comprising: a swinging clutch portion in a keyhole-section shape, including a cylindrical portion extending axially of the drive shaft and a projecting portion extending from the cylindrical portion; a clutch portion housing groove formed in the drive shaft, for housing the cylindrical portion, holding the swinging clutch portion swingably about the cylindrical portion; a collar rotatably fitted onto the drive shaft, having a slit formed in such a manner that a distal end portion of the projecting portion can project therefrom and retract thereinto; at least one engaging groove formed in an inner peripheral surface of the driven member to engage the distal end portion of the projecting portion; and a sealing member interposed between the housing and the collar for preventing the collar from rotating together with rotation of the drive shaft; wherein, when the swinging clutch portion is raised by the collar rotating more slowly than the drive shaft rotates, the distal end portion of the projecting portion projects from a periphery of the slit, thereby engaging the engaging groove; and when the swinging clutch portion is laid down, the distal end portion of the projecting portion retracts into the slit, thereby disengaging from the engaging groove.
The one-way clutch is thus simply configured only by making the clutch portion housing groove in a circular groove corresponding to the cylindrical portion, making the swinging clutch portion in a combined shape of a cylinder and a prism, forming the collar in a steel pipe shape, and forming the slit correspondingly to the projecting portion, thereby favorably eliminating the need for setting the accuracy of fabricating each component at a high degree.
Further, the projecting portion can be swung with the cylindrical portion of the swinging clutch portion fitted in the clutch portion housing groove of the drive shaft as the pivot in close contact with the clutch portion housing groove, providing an advantage of securely transmitting power without impacts.
The clutch portion housing groove formed in the drive shaft is preferably formed at a position radially offset from a shaft center of the drive shaft.
A preferred embodiment of the present invention will be described in detail below, by way of example only, with reference to the accompanying drawings, in which:
For the description of the present embodiment, a lawn mower will be exemplarily illustrated as an embodiment employing power transmission mechanisms according to the present invention.
A lawn mower 10 shown in
The lawn mower 10 includes a body frame 12, right and left front wheels 13 mounted to the body frame 12 (the right front wheel 13 is not shown because
An operating handle 14 extends obliquely from the rear of the body frame 12 in a rearward and upward direction.
The cutting blade 18 is housed in a cutter housing 16 mounted to a lower middle portion of the body frame 12.
The drive unit 21 includes a driving pulley 24 mounted on the output shaft 17, a driven pulley 26, a belt 25 running between the driving pulley 24 and the driven pulley 26, a drive reduction gear 27 mounted to the body frame 12 and connected to the driven pulley 26, right and left wheel support means 28 (see
As shown in
Right and left driven members 36 are mounted on the first end portion 34 and the second end portion 37 of the drive shaft 33, respectively, with right and left one-way clutches 35 interposed therebetween.
The right and left power transmission mechanisms 32 transmit power from the drive shaft 33, through the driven members 36, 36, to the right and left drive wheels 22, 22 provided on the wheel support means 28, 28. Reference numeral 38 denotes a wheel of the drive wheels 22.
Each wheel support means 28 includes a bracket 42 fixed at its first end to the housing 31 and fitted at its second end to the body frame 12, an axle 43 fixed to the bracket 42, a cover 44 mounted to the axle 43 and the housing 31, and a gear 45 mounted on a boss of the wheel 38, meshing with the driven member 36 provided with the one-way clutch 35.
Now, one of the one-way clutches 35 will be described with reference to
The one-way clutch 35 includes a swinging dutch portion 53, a clutch portion housing groove 54, a collar 55, a slit 56, engaging grooves 57, and a sealing member 61.
The swinging clutch portion 53 has a keyhole-section shape, consisting of a cylindrical portion 51 extending in an axially longitudinal direction (directions of arrows “a”) of the drive shaft 33 and a projecting portion 52 extending from the periphery of the cylindrical portion 51.
The clutch portion housing groove 54 is formed in the drive shaft 33 for housing the cylindrical portion 51 of the swinging clutch portion 53, holding the swinging clutch portion 53 swingably.
The collar 55 is fitted onto the drive shaft 33 rotatably (in directions of arrows “b”). The collar 55 has the slit 56 formed in an axially longitudinal direction so that the projecting portion 52 of the swinging clutch portion 53 can project therefrom and retract thereinto.
The engaging grooves 57 are formed in the driven member 36 for engagement with the projecting portion 52.
The sealing member 61 is interposed between the housing 31 and the collar 55 for preventing the collar 55 from rotating together with the rotation of the drive shaft 33. The sealing member 61 is an oil seal, and is desirably provided with a spring 63.
The drive shaft 33 is rotatably supported by the housing 31 via a bearing 64. Reference numerals 65, 65 denote snap rings, and 66, 66, flat rings.
As shown in
As shown in
For the drive shaft 33, a steel material defined by S48C in JIS is used, for example.
The collar 55 has a tubular body 72 of a steel pipe with a given thickness “t,” having at its first end portion the slit 56 formed in an axially longitudinal direction of the tubular body 72. Slitting facilitates fabrication, and also facilitates the assembly of the swinging clutch portion 53.
For the driven member 36, a spur gear is used, and the facewidth of the spur gear is set at Wt. The driven member 36 may be other than a spur gear, and, for example, a pulley may alternatively be used. For the material of the driven member 36, a sintered material is used, for example.
Each engaging groove 57 is formed in an inner peripheral surface 75 of the driven member 36 with a length approximately half the facewidth Wt. In the embodiment shown in the figure, the three engaging grooves 57 are formed in the inner peripheral surface 75 at equal intervals, but the number thereof can be any.
As shown in
As shown in
Now, the operation of the one-way clutch 35 will be described with reference to
When the engine 15 (see
As described above, the one-way clutch 35 has an advantage that, as shown in
The one-way clutch 35 has the sealing member 61 interposed between the housing 31 and the collar 55 as shown in
As a result, without receiving a rotational driving force of the drive shaft 33, the driven member 36 can be rotated in a direction (direction of arrow “j”), here, a forward direction, by a small force.
When the drive shaft 33 is not rotated, the driven member 36 rotates in a direction in the same manner. That is, the drive wheel 22 (see
The lawn mower 11 shown in
In this embodiment, the power transmission mechanisms of the present invention are exemplarily applied to a lawn mower for description, but are also applicable to one-wheel to four-wheel carriers, cultivators and snow plows.
Obviously, various minor changes and modifications of the present invention are possible in the light of the above teaching. It is therefore to be understood that within the scope of the appended claims the invention may be practiced otherwise than as specifically described.
|Cited Patent||Filing date||Publication date||Applicant||Title|
|US4909365||Jun 16, 1988||Mar 20, 1990||The Toro Company||Freewheeling clutch and implement employing same|
|US4928905 *||May 1, 1989||May 29, 1990||Arena Recreations (Toronto) Limited||One-way clutch assembly|
|US6354414 *||Jun 15, 2000||Mar 12, 2002||Honda Giken Kogyo Kabushiki Kaisha||Clutch mechanism|
|US6575280 *||Jun 11, 2001||Jun 10, 2003||White Consolidated Industries, Inc.||Freewheeling bi-directional clutch|
|JP2001059531A||Title not available|
|Citing Patent||Filing date||Publication date||Applicant||Title|
|US7777444 *||Aug 17, 2010||Honda Motor Co., Ltd.||Travel-driving mechanism for self-propelled working machine|
|US20070272510 *||May 22, 2007||Nov 29, 2007||Honda Motor Co., Ltd.||Travel-driving mechanism for self-propelled working machine|
|U.S. Classification||192/43.1, 192/39, 192/50, 192/46|
|International Classification||F16D41/12, F16D41/06, F16D41/16|
|Cooperative Classification||F16D41/12, F16D41/16|
|European Classification||F16D41/12, F16D41/16|
|Sep 24, 2004||AS||Assignment|
Owner name: HONDA MOTOR CO., LTD., JAPAN
Free format text: ASSIGNMENT OF ASSIGNORS INTEREST;ASSIGNORS:ISHIKAWA, TOMOAKI;MIYAHARA, KAZUYOSHI;REEL/FRAME:015838/0401
Effective date: 20040827
|Dec 9, 2009||FPAY||Fee payment|
Year of fee payment: 4
|Feb 21, 2014||REMI||Maintenance fee reminder mailed|
|Jul 11, 2014||LAPS||Lapse for failure to pay maintenance fees|
|Sep 2, 2014||FP||Expired due to failure to pay maintenance fee|
Effective date: 20140711