WO2015199658A1

WO2015199658A1 - Spring assist starter pulley

Info

Publication number: WO2015199658A1
Application number: PCT/US2014/043897
Authority: WO
Inventors: Andrew Johnson
Original assignee: Husqvarna AB; Husqvarna Consumer Outdoor Products NA Inc
Current assignee: Husqvarna AB; Husqvarna Consumer Outdoor Products NA Inc
Priority date: 2014-06-24
Filing date: 2014-06-24
Publication date: 2015-12-30
Anticipated expiration: 2016-12-24

Abstract

A starting device for an internal combustion engine includes a starter pulley including a coil spring to absorb compression shock produced by the engine.

Description

SPRING ASSIST STARTER PULLEY

TECHNICAL FIELD

The present disclosure relates to a starting device for an internal combustion engine. Specifically, the present disclosure relates to a starter pulley including a coil spring to absorb compression shock produced by the engine.

BACKGROUND

Internal combustion engines are often provided with a manual starting mechanism. For example, lawn care devices having engines often include a rope starting mechanism for starting the engine. The rope starter uses the force from the operator to rotate an associated pulley, which in turn is coupled, through one or more components, to the crankshaft of the engine. The starter can include a rope pulley and hub for coupling with a clutch mechanism of the internal combustion engine. When starting an engine, the operator may experience return forces from the engine as the rope is pulled and the components of the engine are subsequently rotated. It is desirable to provide manual starting mechanisms that can absorb, and therefore reduce, such return forces.

The present invention recognizes and addresses certain or all of the foregoing considerations, and others, of prior art constructions and methods.

BRIEF SUMMARY OF SOME EXAMPLES

One embodiment of a spring assist starter pulley in accordance with the present disclosure includes a rope pulley with a substantially cylindrical spring recess that is concentric about a longitudinal center axis of the rope pulley and at least one catch recess that is disposed radially outwardly from the spring recess, the rope pulley being configured to have a starter rope coiled about the rope pulley so that uncoiling the starter rope therefrom causes the rope pulley to rotate in a first direction, a coil spring that is disposed in the spring recess of the rope pulley, the coil spring having a first end and a second end, the first end being non-rotatably fixed to the rope pulley, a hub including a proximal end that is rotatably connected to the rope pulley and a distal end that is operably connected to the internal combustion engine, the second end of the coil spring being non-rotatably fixed to the hub, and a hub retainer including at least one axially extending leg that is slidably received in the at least one catch recess so that a portion of the hub is disposed between the hub retainer and the rope pulley, thereby retaining the hub in a fixed axial position with regard to the rope pulley.

Another embodiment of a spring assist starter pulley in accordance with the present disclosure includes a rope pulley configured to have a starter rope coiled about the rope pulley so that uncoiling the starter rope therefrom causes the rope pulley to rotate in a first direction, a coil spring having a first end and a second end, the first end being non-rotatably fixed to the rope pulley, a hub including a proximal end that is rotatably connected to the rope pulley and a distal end that is operably connected to the internal combustion engine, the second end of the coil spring being non-rotatably fixed to the hub, and a hub retainer including at least one axially extending leg that is non- rotatably fixed to a portion of the rope pulley that is disposed radially outwardly of the coil spring, wherein portion of the hub is disposed between the hub retainer and the rope pulley so that the hub is retained in a fixed axial position with respect to the rope pulley.

The accompanying drawings, which are incorporated in and constitute a part of this specification, illustrate one or more embodiments of the invention and, together with the description, serve to explain the principles of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

A full and enabling disclosure of the present invention, including the best mode thereof, directed to one of ordinary skill in the art, is set forth in the specification, which makes reference to the appended drawings, in which:

Figure 1 is a perspective view of a spring assist starter pulley in accordance with an embodiment of the present disclosure, disposed in a housing of a corresponding lawn care device;

Figure 2 is an exploded front perspective view of the spring assist starter pulley shown in Figure 1 ;

Figure 3 is an exploded rear perspective view of the spring assist starter pulley shown in Figure 1 ; and

Figure 4 is a schematic diagram of a hand-held power driven tool including the spring assist starter pulley as shown in Figure 1.

Repeat use of reference characters in the present specification and drawings is intended to represent same or analogous features or elements of the invention according to the disclosure. DETAILED DESCRIPTION

Reference will now be made in detail to presently preferred embodiments of the disclosure, one or more examples of which are illustrated in the accompanying drawings. Each example is provided by way of explanation, not limitation, of the invention. In fact, it will be apparent to those skilled in the art that modifications and variations can be made in the present invention without departing from the scope and spirit thereof. For instance, features illustrated or described as part of one embodiment may be used on another embodiment to yield a still further embodiment. Thus, it is intended that the present disclosure covers such modifications and variations as come within the scope of the appended claims and their equivalents.

Referring now to the figures, Figure 1 illustrates a spring assist starter pulley assembly including a spring assist starter pulley 100 in accordance with an embodiment of the present disclosure. As shown, spring assist starter pulley 100 is a rope-pull starting device for an internal combustion engine 210 of a hand-held power driven tool 200, as shown in Figure 4. Examples of hand-held power driven tools include, but are not limited to, line trimmers, leaf blowers, chainsaws, snow blowers, and other tools having an internal combustion engine for driving a tool.

Referring additionally to Figures 2 and 3, starter pulley 100 may include a rope pulley 110 (e.g. , for holding a starter rope 120 coiled around rope pulley 110), a hub 130 rotatably secured to rope pulley 110 by a hub retainer 150, and a coil spring 170 received in a spring recess 112 defined by rope pulley 110. Preferably, starter pulley 100 is constructed so that starter rope 120 is coiled on the rope pulley 110 and can be uncoiled therefrom by an operator without starter rope 120 separating from rope pulley 110. This is accomplished by coupling starter rope 120 to rope pulley 110 at an anchored end (not shown). Note, however, in alternate embodiments, starter rope 120 may come free of rope pulley 110 during starting, as is sometimes common with larger engines, such as those found on riding mowers. A pull handle 122 is coupled to a distal end of starter rope 120 that is opposite from the anchored end. Starter rope 120 can be constructed of a natural or synthetic material.

As best seen in Figures 2 and 3, rope pulley 110 includes a first annular sidewall

114 and a second annular sidewall 116 that are substantially parallel to each other and define a first annular recess 118 therebetween. First annular recess 118 of rope pulley 110 is configured and sized such that starter rope 120 may be coiled and uncoiled repeatedly therein during starting operations of the lawn care device. As noted above, a first end of starter rope 120 is preferably affixed to rope pulley 110 so that starter rope 120 remains fixed to rope pulley 110 during starting operations. As best seen in Figure 2, rope pulley 110 further includes a cylindrical first inner wall 124 and a cylindrical second inner wall 126 that is concentric to, and disposed radially outwardly of, first inner wall 124. First inner wall 124 and second inner wall 126 define a cylindrical spring recess 112 therebetween, spring recess 112 being sized and configured to receive coil spring 170 therein, as discussed in greater detail below. As shown in Figure 3, rope pulley 110 defines an axially extending spring aperture 123 that is configured to slidably receive a first end 172 of coil spring 170 when coil spring 170 is disposed within spring recess 112. As such, first end 172 of coil spring 170 is non-rotatably fixed to rope pulley 110.

As well, first inner wall 124 of rope pulley 110 defines a cylindrical mounting aperture 127. Mounting aperture 127 is configured to rotatably receive a correspondingly dimensioned stub shaft 108 (Figure 1) that depends inwardly from an inner surface of housing 102. As such, rope pulley 110 is free to rotate about the stub shaft 108 when mounted thereon. As shown in Figure 1 , rope pulley 110 is axially maintained on the stub shaft 108 by a pair of retention tabs 106 that are secured to the inner surface of housing 102 by a corresponding pair of fasteners 104. A distal end of each retention tab 106 extends radially inward toward the longitudinal center axis of rope pulley 110 such that each retention tab 106 extends inwardly beyond an outer perimeter 128 of the rope pulley's second sidewall 116, thereby maintaining rope pulley 110 on stub shaft 108.

As best seen in Figure 3, a second annular recess 119 is formed in second sidewall 116 of rope pulley 110, second annular recess 119 being concentric about shaft aperture 127. Second annular recess 119 is sized and configured to receive a recoil spring (not shown) that is utilized to recoil starter rope 120 on rope pulley 110 after each pull of the rope by the operator. As is known, a first end of the recoil spring is non- rotatably fixed to rope pulley 110, whereas a second end of the recoil spring is non- rotatably fixed to a portion of housing 102. As such, as starter rope 120 rotates rope pulley 110, the recoil spring stores energy as the recoil spring transitions from a first state to a second state. In the first state, the recoil spring is "at rest" and exerts little to no force upon rope pulley 110. When starter rope 120 is unwound from rope pulley 110, the recoil spring urges rotation of rope pulley 110 in a direction opposite from the direction that starter rope 120 is unwound from rope pulley 110. As such, the recoil spring causes starter rope 120 to retract and coil upon rope pulley 110 when the operator releases pull handle 122 of starter rope 120.

As best seen in Figure 2, rope pulley 110 further includes a plurality of catch recesses 121 that are defined by, and extend through, both first and second sidewalls 114 and 116 of rope pulley 110. The disclosed embodiment of rope pulley 110 preferably includes three (3) catch recesses 121 that are disposed radially outwardly of second inner wall 126 and are both concentric thereto and equally spaced circumferentially thereabout. Each catch recess 121 extends from an outer surface of first sidewall 114 to an outer surface of second sidewall 116, terminating in second annular recess 119. As shown, each catch recess 121 is semi-cylindrical in shape and configured to slidably receive a corresponding axially extending leg 156 of hub retainer 150, as discussed in greater detail below. Note, however, in alternate embodiments, catch recesses 121 may have any number of cross-sectional shapes, dependent upon the cross- sectional shape of the corresponding hub retainer legs that they slidably receive.

As previously noted, coil spring 170 is received in first annular recess 118 of rope pulley 110 and is non-rotatably fixed thereto by first end 172 of coil spring 170 which is received in a corresponding spring aperture 163. Further, coil spring 170 has a second end 174 that is slidably received in an axially extending spring aperture 140 of hub 130. As such, second end 174 of coil spring is non-rotatably fixed to hub 130. As shown, first and second ends 172 and 174, respectively, of coil spring 170 are substantially parallel to a longitudinal center axis of the spring, as are spring apertures 163 and 140 of rope pulley 110 and hub 130, respectively. As shown, hub 130 preferably includes an annular base wall 132, a body portion 134 and a cam portion 138 extending axially therefrom. In the assembled configuration, as shown in Figure 1, a bottom surface of annular base wall 132 is configured to be rotatably received adjacent a portion of the outer surface of the rope pulley's first sidewall 114, that portion of the first sidewall's outer surface being disposed radially inwardly of catch recesses 121. As such, when assembled, hub 130 encloses coil spring 170 within first annular recess 118 of rope pulley 110.

As noted above, hub 130 is rotatably retained adjacent first sidewall 114 of rope pulley 110 by hub retainer 150. Hub retainer 150 includes an annular portion 152 defining a circular hub aperture 154, and a plurality of axially extending legs 156 extending rearwardly from annular portion 152. As previously noted, each axially extending leg 156 of hub retainer 150 is similarly cross-sectionally shaped to the corresponding catch recess 121 of rope pulley 110, so that each axially extending leg 156 may be slidably received therein. Further, each axially extending leg 156 of hub retainer 150 includes a radially outwardly (or inwardly) depending catch 158 disposed on its distal end. Each catch 158 includes a chamfered leading edge 162 to facilitate insertion of each axially extending leg 156 into the corresponding catch recess 121, and a planar trailing edge 160 that is substantially perpendicular to the longitudinal center axis of hub retainer 150.

During assembly of the spring assist starter pulley, as each axially extending leg 156 of hub retainer 150 is inserted into its corresponding catch recess 121 of rope pulley 110, leading edge 162 of each catch 158 contacts the radially outermost sidewall of the corresponding catch recess 121, causing the axially extending legs 156 to be deflected radially inwardly. Upon full insertion of axially extending legs 156 of hub retainer 150 in the corresponding catch recesses 121, each axially extending leg 156 is free to return to its non-deflected position. In the non-deflected position, trailing edge 160 of each catch 158 abuts a correspondingly planar edge of the second sidewall' s outer surface that is disposed adjacent the corresponding catch recess 121, thereby retaining hub retainer 150, and therefore hub 130, in an axially-fixed position with respect to rope pulley 110. Note, in this position, the bottom surface of the hub retainer's annular portion 152 is adjacent a correspondingly shaped ledge 136 of hub 130 that is disposed between an outer perimeter of annular base wall 132 and body portion 134, thereby axially fixing hub 130 to rope pulley 110. However, hub 130 is free to rotate relative to rope pulley 110 in that hub aperture 154 is correspondingly shaped (circular), and has a slightly greater diameter than does cam portion 138, which extends therethrough.

In use, an operator grips pull handle 122 of starter rope 120 and pulls rapidly. As starter rope 120 is unwound from rope pulley 110, rope pulley 110 rotates about its longitudinal center axis. As previously noted, hub 130 is interconnected to rope pulley 110 by coil spring 170 so that hub 130 is both rotatable with and relative to rope pulley 110. As shown, hub 130 includes a one-way rotative mechanism that allows the hub 130 to transfer a starting force to the internal combustion engine. Specifically, cam portion 138 of hub 130 includes cam teeth 142 that are configured to interconnect with a clutch (not shown) or other intermediary mechanism which can transfer the starting force to the internal combustion engine, thereby causing rotation of the crankshaft. Cam teeth 142 are configured so that hub 130 transfers the starting force to the internal combustion engine only in a single direction of rotation, that being the direction of rotation of rope pulley 110 during the uncoiling of starter rope 120 therefrom. As the illustrated hub 130 includes four cam teeth 142, an example clutch mechanism may likewise include four pawls to transfer the starting force therebetween. In yet other embodiments, the number of cam teeth 142 and pawls can differ in number, for example, there can be fewer pawls than cam teeth.

As best seen in Figure 2, hub 130 is configured to drivingly engage the internal combustion engine when hub 130 is rotated in a first direction 180, that being the same direction in which rope pulley 110 is rotated as starter rope 120 is uncoiled therefrom. As shown, when viewing starter pulley 100 from the front, as in Figure 2, first direction 180 is the clockwise direction. As starter rope 120 is initially pulled, rope pulley 110 is instantly rotated in first direction 180, whereas the rotation of hub 130 in first direction 180 is delayed slightly since it is engaged with, and transferring rotational force to, the stationary crankshaft of the internal combustion engine. As noted above, first end 172 of coil spring is fixed to rope pulley 110, whereas second end 174 of coil spring 170 is fixed to hub 130. As such, the initial rotation of rope pulley 110 in first direction 180 with respect to hub 130 causes coil spring 170 to uncoil slightly in a second direction 182, that being the counter-clockwise direction, that is opposite to first direction 180. However, as the operator continues to pull starter rope 120, coil spring 170 eventually urges hub 130 to rotate in first direction 180 and drivingly engage the internal combustion engine. When coil spring 170 is uncoiled slightly as described above, or in the "loaded state, " the coils of coil spring 170 contracts from a first diameter to a slightly smaller second diameter as the rotative force is transferred from rope pulley 110 to hub 130. However, it should be appreciated that the coil spring 170 could also expand if wound in the opposing direction.

Preferably, first annular recess 118 that receives coil spring 170 therein can have an outer diameter that is substantially similar to the increased second diameter of coil spring 170 that occurs during starting operation, as discussed above. For example, when coil spring 170 is in the expanded diameter state, or loaded state, the individual coils of coil spring 170 may abut the inner cylindrical surface of first annular recess 118. As such, first annular recess 118 can prevent the diameter of coil spring 170 from exceeding a predetermined amount, thereby avoiding possible deformation of coil spring 170.

While one or more preferred embodiments of the invention are described above, it should be appreciated by those skilled in the art that various modifications and variations can be made in the present invention without departing from the scope and spirit thereof. It is intended that the present invention cover such modifications and variations as come within the scope and spirit of the appended claims and their equivalents.

Claims

CLAIMS What is claimed is:

1. A spring assist starter pulley assembly for an internal combustion engine (210), comprising:

a rope pulley (110) including a substantially cylindrical spring recess (112) that is concentric about a longitudinal center axis of the rope pulley (110) and at least one catch recess (121) that is disposed radially outwardly from the spring recess (112), the rope pulley (110) being adapted to have a starter rope (120) coiled thereon such that uncoiling of the starter rope (120) causes the rope pulley (110) to rotate in a first direction (180); a coil spring (170) that is disposed in the spring recess of the rope pulley (112), the coil spring (170) having a first end (172) and a second end (174), the first end (172) being non-rotatably fixed to the rope pulley (110);

a hub (130) including a proximal end (132) that is rotatably connected to the rope pulley (130) and a distal end (138) that is operably connected to the internal combustion engine (210), the second end (174) of the coil spring (170) being non-rotatably fixed to the hub (130); and

a hub retainer (150) including at least one axially extending leg (156) that is slidably received in the at least one catch recess (121) so that a portion of the hub (130) is disposed between the hub retainer (150) and the rope pulley (110), thereby retaining the hub (130) in a fixed axial position with regard to the rope pulley (110).

2. The spring assist starter pulley assembly of claim 1 , wherein the rope pulley (110) further comprises a cylindrical first inner wall (124) and a cylindrical second inner wall (126) that is concentric to the first inner wall (124) and disposed radially outwardly therefrom, the first inner wall (124) and the second inner wall (126) defining the spring recess.

3. The spring assist starter pulley assembly of claim 2, wherein the rope pulley (110) further comprises an annular first sidewall (114) and an annular second sidewall (116), the first sidewall (114) and the second sidewall (116) extending radially outwardly from the second inner wall (126) so that a first annular recess (118) is formed therebetween, the starter rope (120) being disposed in the first annular recess.

4. The spring assist starter pulley assembly of any of claims 1-3, wherein the first end (172) and the second end (174) of the coil spring (170) extend axially from opposite ends of the coil spring (170) and are substantially parallel to a longitudinal center axis of the coil spring (170).

5. The spring assist starter pulley assembly of any of claims 1-4, wherein the hub retainer (150) further includes an annular portion (152) defining a hub aperture (154), the at least one axially extending leg (156) extends from an outer perimeter of the annular portion (152), and the distal end (138) of the hub (130) extends outwardly through the hub aperture (154).

6. The spring assist starter pulley assembly of any of claims 1-5, wherein the distal portion (138) of the hub (138) further comprises a cam including a plurality of cam teeth (142) that are configured to selectively engage a portion of the internal combustion engine (210).

7. The spring assist starter pulley assembly of any of claims 1-6, wherein the portion of the hub (130) that is disposed between the hub retainer (150) and the rope pulley (110) is an annular base wall (132), the annular base wall (132) abutting a bottom surface of the annular portion (152) of the hub retainer (150).

8. The spring assist starter pulley assembly of any of claims 5-7, wherein: the at least one axially extending leg (156) of the hub retainer (150) further comprises three axially extending legs (156) spaced evenly about the outer perimeter of the annular portion (152); and

the at least one catch recess (121) of the rope pulley (110) further comprises three catch recesses (121) spaced evenly about the spring recess (112) of the rope pulley (110),

wherein each axially extending leg (156) is slidably received in a corresponding catch recess (121).

9. The spring assist starter pulley assembly of any of claims 1-8, wherein the hub retainer (150) is non-rotatably fixed to the rope pulley (110).

10. The spring assist starter pulley assembly of any of claims 1-9, wherein the at least one axially extending leg (156) of the hub retainer (150) further includes a radially outwardly or inwardly depending catch (158) disposed at its distal end, the radially extending catch (158) engaging a surface (125) of rope pulley (110) that is adjacent the at least one catch recess (121), thereby axially retaining the hub retainer

(150) to the rope pulley (110).

11. A tool (200) comprising the spring assist starter pulley assembly of any of claims 1-10.

12. A spring assist starter pulley assembly for an internal combustion engine (210), comprising:

a rope pulley (110) adapted to have a starter rope coiled thereon such that uncoiling of the starter rope (120) causes the rope pulley (110) to rotate in a first direction (180);

a coil spring (170) having a first end (172) and a second end (174), the first end (172) being non-rotatably fixed to the rope pulley (110);

a hub (130) including a proximal end (132) that is rotatably connected to the rope pulley (110) and a distal end (138) that is operably connected to the internal combustion engine (210), the second end (174) of the coil spring (170) being non-rotatably fixed to the hub (130); and

a hub retainer (150) including at least one axially extending leg (156) that is non- rotatably fixed to a portion of the rope pulley (110) that is disposed radially outwardly of the coil spring (170),

wherein the proximal end (132) of the hub (132) is disposed between the hub retainer (150) and the rope pulley (110) so that the hub (130) is retained in a fixed axial position with respect to the rope pulley (110).

13. The spring assist starter pulley assembly of claim 12, wherein the rope pulley (110) further comprises a substantially cylindrical spring recess (112) that is concentric about a longitudinal center axis of the rope pulley (110), and the coil spring

(170) is disposed in the spring recess (112).

14. The spring assist starter pulley assembly of claim 13, wherein the roper pulley (110) further comprises at least one catch recess (121) that is disposed radially outwardly or inwardly from the spring recess (112), and that at least one axially extending leg (156) of the hub retainer (150) is slidably received in the at least one catch recess (121).

15. The spring assist starter pulley assembly of claim 14, wherein:

the at least one axially extending leg (156) of the hub retainer (150) further comprises three axially extending legs (156) spaced evenly about an outer perimeter of the hub retainer (150); and the at least one catch recess (121) of the rope pulley (110) further comprises three catch recesses (121) spaced evenly about the spring recess (112) of the rope pulley (110),

16. The spring assist starter pulley assembly of any of claims 13-15, wherein the rope pulley (110) further comprises a cylindrical first inner wall (124) and a cylindrical second inner wall (126) that is concentric to the first inner wall (124) and disposed radially outwardly therefrom, the first inner wall (124) and the second inner wall (126) defining the spring recess (112).

17. The spring assist starter pulley assembly of claim 16, wherein the rope pulley (110) further comprises an annular first sidewall (114) and an annular second sidewall (116), the first sidewall (114) and the second sidewall (116) extending radially outwardly from the second inner wall (126) so that a first annular recess (118) is formed therebetween, the starter rope (120) being disposed in the first annular recess (118).

18. The spring assist starter pulley assembly of any of claims 12-17, wherein the first end (172) and the second end (174) of the coil spring (170) extend axially from opposite ends of the coil spring (170) and are substantially parallel to a longitudinal center axis of the coil spring (170).

19. The spring assist starter pulley assembly of any of claims 12-18, wherein the hub retainer (150) further includes an annular portion (152) defining a hub aperture (154), the at least one axially extending leg (156) extends from an outer perimeter of the annular portion (152), and the distal end (138) of the hub (130) extends outwardly through the hub aperture (154).

20. The spring assist starter pulley assembly of claim 19, wherein the portion of the hub (130) that is disposed between the hub retainer (150) and the rope pulley (110) is an annular base wall (132), the annular base wall (132) abutting a bottom surface of the annular portion (152) of the hub retainer (150).

21. The spring assist starter pulley assembly of any of claims 12-20, wherein the at least one axially extending leg (156) of the hub retainer (150) further includes a radially outwardly depending catch (158) disposed at its distal end, the radially extending catch (158) engaging a surface (125) of the rope pulley (110) that is substantially perpendicular to the longitudinal center axis of the rope pulley (110), thereby axially retaining the hub retainer (150) to the rope pulley (110).

22. A tool (200) comprising the spring assist starter pulley assembly of any of claims 12-21.