EP1194700A1

EP1194700A1 - Snap fit push/pull cable control assembly

Info

Publication number: EP1194700A1
Application number: EP00941552A
Authority: EP
Inventors: Charles Eakins; Alan Waldhour; Chris Darieng
Original assignee: Capro Ltd
Current assignee: Kongsberg Power Products Systems I LLC
Priority date: 1999-06-18
Filing date: 2000-06-19
Publication date: 2002-04-10
Also published as: WO2000079143A1

Abstract

A snap fit is provided between a control knob (1) and cable housing (13) by a pair of facing protruding lips (3 and 9), one each on the control knob (1) and the end of the cable housing (13). One lip (3 and 9) passes over the other lip (9 or 3) in close abutment when the control knob (1) is fully depressed.

Description

Snap Fit Push/Pull Cable Control Assembly

Field of the Invention The present invention pertains to a snap fit push/pull control assembly of the type typically used for manual control of the choking mechanism on a carburetor. ore particularly, the push/pull control assembly of the present invention both shields the cable sleeve from the entry of dirt and moisture when used to control a choking mechanism on a carburetor and prevents the choke control assembly from being displaced from the position associated with an un-choked carburetor. While the disclosed snap fit push/pull control assembly can be used on a wide array of devices, it will be explained by its use on a piece of equipment employing a fuel system including a choke assembly which is controlled by a Bowden type wire control cable as described in Bowden ' s U.S. Patent No. 609,570. Background

Cable-actuated control assemblies of the push-pull type are sometimes referred to as "Bowden wire controls." Generally speaking, many manually controlled devices are operated remotely via the use of a cable which is moved in a pull -push fashion to either turn off-- or turn on one or more systems on the manually controlled device. The cable is generally contained within a cable sleeve. To enable both a push and a pull movement of the cable, the cable sleeve is typically anchored to the device. A control knob or lever at the proximal or operator end of the cable-actuated control assembly is moved by the operator to adjust the position of cable. Positioning of the cable will turn on, turn off or adjust the position of one or more systems on the device being controlled. A common example is the choke or throttle control of the carburetor on the engine of a tractor, lawnmower, boat, or other machine powered by an internal combustion engine. Choke control assemblies, in particular, irrespective of their design, tend to suffer from the same problem, namely that the choke control assembly is subject to a great deal of vibrational stress. Over time, this vibrational stress may tend to move the choke control assembly out of the off position when the engine is warmed up and running properly. Additionally, travel of the cable within the cable sleeve can be made difficult when debris enters the cable sleeve or when debris, dirt, moisture or ice causes the parts in a choke control assembly to wear prematurely. Various prior art attempts to deal with these two problems have added complexity and expense to the manufacturing process.

Also, pre-setting the position of the choking mechanism at the engine during the manufacturing process can be difficult due to the fact that the connection of the choke control assembly to the engine is done at a location away from the normal operator position. Therefore, the assembly technician cannot always insure that the choke control knob position exactly corresponds with the position of the choking mechanism on the carburetor. This leads to improper control cable assembly settings which are either slow down factory installation or cause the consumer/operator to have to adjust the choke setting mid-range for normal operation. The following references describe exemplary control assemblies .

U.S. Patent No. 3,411,374 to Holly teaches a means of preventing vibrational displacement of the control wire assembly for air vents in an automobile by providing a fixed casing with cantilevered fingers. The cantilevered fingers bear directly against the control wire providing a stress that resists displacement of the control wire.

U.S. Patent No. 3,443,452 by Shontz teaches a means for permanently attaching a control cable assembly to a control panel. A pair of resilient fingers are provided that can flex to move through an opening in a control panel and subsequently re-expand to hold the entire control cable assembly permanently in place.

U.S. Patent No. 4,611,502 by Gregory teaches a means of preventing vibrational displacement of a control cable assembly which uses a spring detent . The spring detent provides the user with a tactile indication of cable placement and prevents unintentional changes from desired settings.

U.S. Patent No. 4,854,185 by Lichtenberg, et al . , teaches a means of locking a control cable assembly into position. The cable housing exterior has a multitude of annular teeth and fits inside a sliding tubular housing with similar teeth. A locking member allows the teeth to engage the appropriate tine, thus, locking the mechanism by the plurality of engaged teeth.

U.S. Patent No. 5,161,428 by Petrucello describes a rotatable mechanism that allows the cable length to be adjusted. The cable length is fixed in place by means of detents. The detents fit into notches adapted therefor.

U.S. Patent No. 5,359,909 by Ito et al . describes a cable control system wherein the movement of the sliding portion of the mechanism is contained between two stopper flanges. Further, the position between the two stopper flanges is controlled by grooves to allow for defined positioning of the cable. Pressure against two outwardly extending arms allows the slider to move away from the grooves and be repositioned. U.S. Patent No. 5,546,827 to Popisil describes a means for keeping dirt from entering the cable sleeve that consists of a flexible boot which expands and contracts as the cable is actuated. The flexible boot is combined with wiper means for cleaning the cable as it is used.

However, all of these prior art mechanisms are costly, both in terms of production costs and in terms of assembly costs . None of the described prior art systems combines a simple cable position locking mechanism with a simple dirt and moisture exclusion mechanism. Thus, there remains a need in the art for a cable position control system that meets the requirements of simplicity, low cost, durability, ease of assembly and precision adjustment combined with failsafe, positively actuated, cable positioning and indicating features. Summary

The snap fit push/pull cable control assembly of the present invention provides a control cable system that is simple, low cost, durable, easy to assemble and provides precision adjustment with failsafe, positively actuated positioning and indicating features.

Included in the snap fit push/pull cable control assembly of the present invention is a snap lock between the knob on the end of the cable and a fitting on the cable housing which may be mounted to a control panel. The positive snap lock between the knob and a fitting on the end of the cable sleeve or housing allows the user to obtain a positive tactile and audible indication that the knob has been properly positioned to the fully depressed or off position by virtue of a "snap" which can be both felt and heard. Further, the snap lock prevents the push/pull cable control system from vibrating from one position to another. When used closed to position a choking mechanism on an internal combustion engine, the snap fit push/pull control assembly of the present invention will prevent the choke control cable from vibrating to a to a closed or fuel rich position while the engine is running, maintaining optimum engine performance while avoiding stalls. Thus, the snap fit push/pull cable control assembly of the present invention aids in pollution control by ensuring correct placement of the choke mechanism during use of the machine.

Further, the snap lock push/pull cable control assembly of the present invention, when made with at least one fully annular ring or "lip," will prevent debris and moisture from entering the cable housing. Thus, the control cable itself is kept clean. This reduces the operating force required to adjust the position of the control cable. The use of a snap fit engagement eliminates the need for a rubber boot as found on prior art push/pull cable control assemblies for the exclusion of debris. Accordingly, the snap fit push/pull cable control assembly of the present invention both reduces manufacturing costs and improves product life.

The present invention has the additional benefit of facilitating the proper assembly of gasoline engine or like powered equipment . One of the problems during assembly of gasoline engine powered equipment is assuring that the choke assembly is in the fully off or fuel lean position before connecting the control cable to the choke assembly on the fuel control system. Oftentimes, the position of the control cable is slightly extended during assembly. Thus, the control cable is in an improper position when connected to the choke assembly on the fuel control system. This improper positioning results in a need to re-adjust the choking mechanism control, either at the factory or by the consumer/operator. If the choking mechanism control remains improperly adjusted, it could result in excessive stress in the inner cable/wire, leading to failure or improper operation of the engine. The snap fit lock of the snap fit choke control of the present invention allows the assembly technician to assure that the control knob is fully depressed or in the fuel lean position by virtue of the "snap" that occurs when the control knob is fully seated. Further, the control knob for the choke control system will not change position during assembly.

"Snap fit" or "snap lock" is defined herein to include any means of providing a reversible locking mechanism that involves only the use of protrusions or protrusion/depression combinations. Coiled spring locks and other sophisticated devices are not included. When one or more parts are slightly flexed (usually by virtue of using a flexible material), a protrusion passes over another protrusion and/or into a depression, allowing the two parts to tightly fit together with the protrusion (s) now preventing accidental displacement of the device through vibration of the machine. The parts can be disconnected or unlocked, however, with the application of manual force sufficient to again flex the part allowing the protrusion (s) to pass by or out of a depression. A common example of a snap lock is generally found on some plastic pen caps.

Brief Description of the Drawing Figures

A better understanding of the snap fit push/pull control assembly of the present invention may be had by reference to the figures wherein: Figure 1 is an elevational view of the preferred embodiment of the snap fit push/pull cable control assembly of the present invention; Figure 2 is a cross-sectional view through line A-A of Figure 1 ;

Figure 3 is a cross-sectional view of a first alternate embodiment of the snap fit push/pull cable control assembly where the control knob fits inside the fitting on the end of the cable housing to provide the snap fit;

Figure 4 is a cross-sectional view of the snap fit push/pull cable control assembly shown in Figure 3 in the fully depressed or off position; Figure 5 is a cross-sectional view of a second alternate embodiment of the snap fit push/pull cable control assembly with a protrusion/depression snap fit mechanism. Description of Embodiments

Figure 1 is a front elevational view of the snap fit push/pull or control assembly 10 of the present invention. Figure 2 shows a cross section through the midline A-A of the same assembly 10. The control knob 1 on the proximal or operator end of the control system has an annular groove 21 which creates a cantilevered wall 25. The cantilevered wall 25 ends with an interior protruding lip 3. The control knob 1 is attached by conventional means to a plunger rod 5 or the control knob 1 may be formed integrally with the plunger rod 5. The plunger rod 5 fits into a cable guide sleeve 13. The cable guide sleeve 13 is a hollow tubular sleeve of sufficient size to contain the plunger rod 5 and allow its free motion therethrough. The distal end 15 of the plunger rod 5 is connected to any type of cable or control wire (not shown) used for controlling the position of a choke on the fuel system of a gasoline engine or a similar push/pull control mechanism. The cable guide sleeve 13 has a proximal end 11, a central portion 12 and a distal end 17. The central portion 12 is adapted by any one of a variety of connecting means to allow the cable guide sleeve 13 to be anchored to a portion of the machine, typically the dashboard. Screw threads 8 are depicted as one of many possible anchoring means in Figure 1. The screw threads 8 allow the cable guide sleeve 13 to be screwed into a receptacle with matching threads (not shown) , such as might be present in a control panel or inside a threaded nut. The proximal end 11 of the cable guide sleeve 13 includes a fitting 6 which has an exterior protruding lip 9. The exterior protruding lip 9 allows the interior protruding lip 3 within the choke control knob 1 to snap fit or mate with the lip 9 on the fitting 6.

In order to facilitate the snap fit of the control knob 1 over the protruding lip 9 on the fitting 6, the knob 1 contains an annular groove 21. The annular groove within the choke control knob 1 creates a cantilevered wall 25 that provides a spring bias for the interior protruding lip 3. This groove/wall structure provides increased flexibility and allows the knob 1 to easily slip over the exterior protruding lip 9 on the fitting 6 without causing the exterior protruding lip 3 of the knob 1 to break off. Further, this groove/wall structure leaves a central portion 23 of the knob 1 into which the plunger rod 5 can be fitted. If desired, the annular groove 21 can be much shallower than is depicted in Figure 2, and still provide sufficient flexibility to enable the desired snap fit connection. The groove 21 need only be deep enough to allow the proximal end of the fitting 6 to snap fit therein to. Additional flexibility can be provided by providing slots (not shown) in the annular ring or wall of the knob 1.

Figures 1 and 2 show that the exterior of the cable sleeve 13 is fitted with screw threads 8. The screw threads 8 allow the cable sleeve 13 to be screwed into an appropriately threaded receptacle on the machine. However, any anchoring means can be used in combination with a separate instrument panel or directly attached to a portion of the machine, such as a lawnmower handle. Anchoring means may include a bracket that can be screwed, bolted, glued, clamped, riveted or otherwise attached to the machine, or the use of resilient fingers that expand after insertion through a hole in a panel. For aesthetics the distal end 19 of the fitting 6 may be flared such that the hole into which the cable guide sleeve 13 is fitted is fully covered by the flare. The flared end also prevents debris from entering the space behind the control panel and may itself provide the anchoring means if fitted with holes for fasteners, resilient fingers, etc. or if glued or otherwise attached to the panel.

In a preferred embodiment, the cable housing with anchoring means is integrally made from, for example, an injection-molded polymer which provides corrosion resistance and ease of manufacturing or a processed metal . The plunger rod 5 can be a polymer or a metal, or it can also be polymer that is plated with a metal on its exterior surface. The embodiment 10 shown in Figure 1 depicts the control knob 1 making a snap fit over the lip 9 on the proximal end of the fitting 6. However, the position of the engaging lips may be reversed such the fitting 6 snap fits over the knob 1. This first alternate embodiment 100 is shown in Figure 3 where the cantilevered wall 250 created by the annular space 210 ends in an interior protruding lip 30 on the proximal end of the fitting 26. The other protruding lip 90 is on the control knob 1. Figure 4 shows the same snap fit push/pull cable assembly 100 in a closed position after engagement of the two lips 30, 90 has provided the snap fit. Means for attaching the fitting 110 are also shown.

In Figure 5, a second alternate embodiment of the snap fit push/pull cable control assembly 200 of the present invention includes protrusions 31 on the control knob, a protrusion 91 on fitting 36. A depression 41 under protrusion 31 is shown. The protrusion 91 can be flexed slightly to fit over the slight protrusion 31 on the end of the knob 1 and then fit into the depression 41 on the control knob 1. As shown in prior embodiments, this arrangement can be reversed. The lips described herein may be completely annular, but need not be. They could also be arranged radially, but broken into multiple detents if desired. However, for simplicity and sealing an annular lip is preferred. Further, where at least one lip is completely annular (e.g., forms a complete circle or ring) , the lip also functions to exclude debris from the cable conduit. Varying the size or the number of the lips and/or depressions, the materials and moisture, and the number of slots in the annular lips, will control the degree of force required to position the snap fit push/pull cable control assembly of the present invention.

A tubular cable housing or sleeve has been described that is circular in cross section, such that the knob and its lip are annular to snap fit or mate with the cable housing. However, the cable housing or sleeve could be any shape in cross section, including square, hexagonal, etc. The control knob and its lip are shaped accordingly. The above description is illustrative only and should not be considered limiting, except as specifically provided in the appended claims:

Claims

What is claimed is: 1. A snap fit push/pull control assembly comprising: a) a hollow tubular cable sleeve having a proximal end, a central portion and a distal end; b) a knob having a plunger rod inserted therein to, said plunger rod passing through said hollow tubular sleeve, c) means for snap locking said knob and said proximal end of said cable sleeve together.

2. The snap fit push/pull control assembly of claim 1, wherein said means for snap locking said knob and said proximal end together further includes : an exterior facing lip and an interior facing lip, and wherein said interior facing lip passes over the exterior facing lip.

3. The snap fit push/pull control assembly as defined in claim 1, further including means for anchoring said central portion of said hollow tubular cable sleeve to a surface.

4. The snap fit push/pull control assembly as defined in claim 3, wherein said means for anchoring is selected from the group consisting of a bracket, at least one resilient finger, or a threaded connection.

5. The snap fit push/pull control assembly as defined in claim 4, wherein said means for anchoring is integrally formed on said hollow tubular cable sleeve.

6. The snap fit push/pull control assembly as defined in claim 2, wherein at least one of said exterior facing lip and said interior facing lip are annular.

7. A snap fit push/pull cable control assembly for use on a machine, said snap fit push/pull cable control assembly comprising: a) a hollow tubular cable sleeve having a proximal end, a central portion and a distal end; b) said central portion having an anchor for anchoring said cable sleeve to a machine; c) said proximal end having a flared fitting with at least one first annular lip; d) a knob and plunger rod assembly, said plunger rod connected at a proximal end to said knob, thence passing through the hollow tubular cable sleeve and being connected at a distal end to a cable; e) said knob having at least one second annular lip, said at least one first annular lip and said at least one second annular lip passing each other when said knob is moved to the fully closed position m order to provide a snap fit lock.

8. The snap fit push/pull cable control assembly as defined in claim 7, wherein said at least one first annular lip is an exterior facing lip and said at least one second annular lip is an interior facing lip and said internally facing lip passes over said exterior facing lip when the knob is moved to the fully closed position.

9. The snap fit push/pull cable control assembly as defined in claim 7, wherein said at least one second annular lip is an exterior facing lip and said at least one first annular lip is an interior facing lip and said internally facing lip first annular lip passes over said exterior facing second annular lip when the knob is moved to the fully closed position.

10. The snap fit push/pull cable control assembly as defined in claim 7, wherein said hollow tubular cable sleeve is integrally formed.

11. The snap fit push/pull cable control assembly as defined in claim 8, wherein said hollow tubular cable sleeve is integrally formed.

12. The snap fit push/pull cable control assembly as defined in claim 9, wherein said hollow tubular cable sleeve is integrally formed.

13. A cable control assembly for use on a machine, said cable control assembly comprising: a) a hollow tubular cable sleeve having a proximal end, a central portion and a distal end; b) said central portion having an anchor for attaching said cable sleeve to a machine; d) said proximal end having a flared fitting with an exterior protruding lip; e) a knob having a central portion and a distal end, an annular groove on said distal end creating a wall ending in an interior protruding lip, f) a plunger rod having a proximal end and a distal end, and being connected at said proximal end to the central portion of said knob, passing through said hollow tubular cable sleeve and being connected at said distal end to a cable; g) said interior protruding lip fitting over said exterior protruding lip in close abutment when the knob is moved adjacent said flared base to provide a snap lock.

14. An improved choke cable control assembly, wherein said improvement comprise means for providing a snap lock fit when said choke cable is in a fuel lean or operating position.

15. The improved choke cable control assembly as defined in claim 14, wherein said means for providing a snap lock fit includes at least one annular lip.

16. The improved choke cable control assembly as defined in claim 14, wherein said means for providing a snap lock fit includes at least one annular lip and a depression into which said at least one annular lip fits when said cable control is the fully depressed position.

17. The improved choke cable control assembly as defined in claim 14, wherein said means for providing a snap lock fit consists essentially of two annular lips.

18. A method of positively positioning a push/pull cable control assembly comprising the steps of : connecting a control cable to a plunger rod; passing said plunger rod through a sleeve and a fitting, said fitting having an exterior lip; connecting said plunger rod to a knob; said know having an interior lip constructed and arranged to snap fit over said exterior lip on said fitting.