Patent Grant
9175732
The subject matter disclosed herein relates generally to components of a variable speed transmission. More particularly, the subject matter disclosed herein relates to clutch arm designs and linkages for variable speed transmissions.
In one typical kind of clutch engagement/disengagement system, a clutch disengaging unit operates by a sleeve mounted on a guide (e.g., on the output shaft of the transmission). This sleeve can be moved to cause a clutch element to shift between an engaged and disengaged position. For instance, where the clutch element is a friction plate of a plate or disk clutch, movement of the sleeve on the guide can deform a diaphragm spring of the clutch such that pressure plates are disengaged from corresponding friction linings on the clutch disk.
A simple mechanical linkage can serve as the mechanism by which the sleeve is moved to shift the clutch element between the engaged and disengaged positions. Specifically, in one common configuration shown in
Although this simple linkage arrangement can be used for transmitting the motion of control shaft 102 to clutch element 150, the effectiveness of such a component can be compromised by certain aspects of the design. For instance, because arms 104 are independently mounted on control shaft 102, small differences in the positions of arms 104 relative to control shaft 102 can exist because of machining tolerances and the precision of assembly and installation of the components. As a result, it is difficult to ensure that both of arms 104 engage their respective protrusions 106 with groove 110 of sleeve 108 at the same instant and to the same extent. This uneven application of force can lead to uneven wear upon clutch linkage 100 and sleeve 108, sleeve 108 can tend to jam or at least offer a very pronounced resistance to axial movement along guide 112, and pressure can be applied unevenly to clutch element 150, which can reduce the operating life of any bearings connected therewith.
These drawbacks can impede the smooth operation of the clutch and reduce the useful life of sleeve 108 and/or guide 112, especially if sleeve 108 is made of a synthetic material (e.g., plastic). Additional drawbacks of such declutching device designs include the initial cost of manufacture of multiple component parts that make up clutch linkage 100, and installation of all of the parts individually can be time consuming. As a result, it would be desirable for a new declutching device that can operate more consistently than current designs without increasing the cost of manufacture or installation.
In accordance with this disclosure, clutch arm or release devices are provided. In one aspect, a clutch linkage for a variable speed transmission is provided. The clutch linkage can include a control shaft pivotable about an axis, a substantially U-shaped arm connected at two points to the shaft, and a plurality of projections positioned on the arm. The arm can be movable between a first position and a second position in response to pivoting of the control shaft, and the projections can exert a force on a movable sleeve when the substantially U-shaped arm is moved between the first position and the second position.
In another aspect, a clutch arm or release device for a variable speed transmission is provided. The clutch release device can include a sleeve movable between a disengaged position away from a clutch element and an engaged position against the clutch element, a control shaft pivotable about an axis, a substantially U-shaped arm positioned about the sleeve and connected at two points to the shaft, and a plurality of projections positioned on the arm. The projections can link the arm to the sleeve. In this configuration, rotation of the control shaft about the axis moves the arm between a first position and a second position, which in turn moves the sleeve between the disengaged position and the engaged position. In addition, when the arm is moved between the first position and the second position, it can exert a force on the clutch element to move it to an engaged position.
Although some of the aspects of the subject matter disclosed herein have been stated hereinabove, and which are achieved in whole or in part by the presently disclosed subject matter, other aspects will become evident as the description proceeds when taken in connection with the accompanying drawings as best described hereinbelow.
The features and advantages of the present subject matter will be more readily understood from the following detailed description which should be read in conjunction with the accompanying drawings that are given merely by way of explanatory and non-limiting example, and in which:
The present subject matter provides clutch release devices and methods such as for variable speed transmission systems, such as lawnmowers or any other suitable machine for example. In one aspect, the present subject matter provides a clutch linkage in which a single, substantially U-shaped clutch arm is attached to a rotatable control shaft. The single clutch arm can operate in a similar manner to the system having two separate arms to engage a clutch bearing, but because only a single component is needed to make the multiple points of connection, the improved design can provide efficiency and reduce cost in both part manufacturing and assembly.
Specifically, referring to
In this arrangement, sleeve 208 is not fixedly fastened to arms 204, but the interconnection of protrusions 206 in groove 210 allows the movement of arms 204 to cause the axial movement of sleeve 208. As a result, when control shaft 202 is rotated, the movement of arms 204 can cause sleeve 208 to move to engage or disengage a clutch element 150. In particular, referring to
As a result, and as illustrated in
In addition, each of arms 204 can further include a shoulder 214 that can protrude toward clutch element 150 when clutch linkage 200 is installed. When control shaft 202 is rotated, shoulders 214 can exert a force against clutch element 150 to engage clutch element 150 (See., e.g.,
Further, in contrast to typical clutch arrangements, clutch linkage 200 can also include a cross-bar element 220 that connects arms 204 together in an integral manner. As a result, arms 204 are movable together as a unit. Cross-bar 220 can extend between distal ends of arms 204 (i.e., ends opposite the ends connected to control shaft 202), or cross-bar 220 can be connected between arms 204 at any point along their lengths. As shown for example in
Cross-bar 220 can provide a second common line of connection for arms 204 (the first being the axis of control shaft 202 about which arms 204 can be pivoted) so that protrusions 206 on arms 204 are aligned and maintained in the same plane parallel with the axis about which arms 204 can be pivoted. In this way, rather than arms 204 being independently mounted on control shaft 202, the positions of arms 204 are tied together. As a result, problems with manufacturing tolerances and the precision of assembly and installation of the components are less likely to cause the operation problems noted above.
Further, arms 204 and cross-bar 220 can be formed as a single component. Therefore, rather than clutch linkage 200 being composed of three separate components (e.g., control shaft 102 and two arms 104 of the prior art clutch linkage 100 shown in
The present subject matter can be embodied in other forms without departure from the spirit and essential characteristics thereof. The embodiments described therefore are to be considered in all respects as illustrative and not restrictive. Although the present subject matter has been described in terms of certain preferred embodiments, other embodiments that are apparent to those of ordinary skill in the art are also within the scope of the present subject matter.
| Number | Name | Date | Kind |
|---|---|---|---|
| 115792 | Waldo | Jun 1871 | A |
| 1431053 | Smith | Oct 1922 | A |
| 1467681 | Peters | Sep 1923 | A |
| 1545050 | Hansen | Jul 1925 | A |
| 1552368 | Whitacre | Sep 1925 | A |
| 1609741 | Taylor | Dec 1926 | A |
| 1966100 | McAdams et al. | Jul 1934 | A |
| 3372782 | Nieland | Mar 1968 | A |
| 4560052 | Renaud | Dec 1985 | A |
| 4655335 | Maruyamano et al. | Apr 1987 | A |
| 4708230 | Maucher | Nov 1987 | A |
| 4850467 | Parzefall | Jul 1989 | A |
| 5353902 | Flowtow et al. | Oct 1994 | A |
| 7353929 | Brunner et al. | Apr 2008 | B2 |
| 7438170 | Maier et al. | Oct 2008 | B2 |
| 7487696 | Tagami | Feb 2009 | B2 |
| Number | Date | Country | |
|---|---|---|---|
| 20110290613 A1 | Dec 2011 | US |
