DESCRIPTION

This invention relates to a device to translate rotary motion into reciprocating motion. More par¬ ticularly the invention relates to a gear shift mechanism for an automobile wherein the gear shift 5. lever on a steering column is connected by a flexible core to an automatic transmission and wherein rotary or arcuate movement of the gear shift lever will cause the core to move in a straight line movement to actuate the automatic transmission.

10. Conventional steering column gear shift levers are mechanically linked to a lever arm at the bottom of the steering column of an automobile. Because it is necessary for safety purposes to design the steering column to collapse in the event it is impacted in an

15. accident, it is necessary that relatively expensive telescopic shear means be utilized in the gear shift linkage to accommodate a collapse of the steering column. Further the use of such linkages requires use of rods, lever arms and bell cranks resulting in con-

20. siderable weight and in considerable expense involved in forming the various parts and in assembling the parts.

According to the invention there is provided a device to translate rotary motion into reciprocating motion comprising a rigid tubular guide conduit having a first arcuate portion including a keyhole slot 5. extending through a side wall of the conduit, a second straight portion extending substantially perpendicular to the plane of the arcuate portion and a third curved portion connecting the first and second portions, a flexible conduit connected at one end of said second

10. portion opposite the curved portion, a flexible core member capable of transmitting tension and compression loads movable in said rigid guide and flexible con¬ duits, and a tab extension extending through said key¬ hole slot connected to an end of said core member

15. whereby arcuate movement of said tab extension in said keyhole slot transforms a rotary motion of the end of the core member connected to said tab extension into a linear motion of the core member in the straight por¬ tion and in said flexible conduit.

20. Preferably the core member has a flexible sheath engaging its outer periphery adjacent the tab extension and which also engages the inner periphery of the rigid guide conduit. This construction provides a tight fit between the outer periphery of the core member and the

25. inner periphery of the rigid conduit and so prevents any lost motion occurring between the two upon movement of the core member relative to the rigid guide con¬ duit. The length of the flexible sheath is substan¬ tially equal to the length of the first arcuate portion

30. and the third curved joining portion.

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The tab extension is adapted to have a gear shift lever connected thereto and the flexible conduit is adapted to be secured to and to extend in parallel to a steering column. The end of the flexible core member 5. opposite the tab extension may be connected to an automatic transmission.

Such construction eliminates the use of com¬ plicated linkage systems while at the same time provides flexibility in the event the steering column 10. collapses under impact loads since the core and conduit are both flexible.

An embodiment of the invention will now be des¬ cribed by way of example and with reference to the accompanying drawings in which:-

15. Figure 1 is a side sectional view of a steering column of an automobile to which a device constructed according to the invention is applied;

Figure 2 is an enlarged partial sectional plan view of a device constructed according to the invention 20. as applied to an automatic gear shift control of an automobile;

Figure 3 is a partial sectional view of the device of Figure 2;

Figure 4 is an enlarged sectional view of 25. Figure 2 taken along lines 4-4; and

Figure 5 is an enlarged sectional view of Figure 2 taken along lines 5-5.

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Referring to Figures 1 and 2, there is illus¬ trated a steering column 1 of an automobile including a steering wheel 2 and a steering shaft 3. A device for translating rotary motion into a reciprocating motion 5. is mounted on the steering column and forms a part of the automatic transmission control of the automobile.

As shown the device comprises a rigid tubular guide conduit 5 having a first arcuate portion 6, a straight portion 7 which extends substantially perpen-

10. dicular to the plane of the arcuate portion 6 and a third curved portion 8 which joins or connects the por¬ tions 6 and 7. With reference to Figure 2, the plane of the arcuate portion 6 is coplanar with that of the drawing while the second straight portion 7 extends

15. perpendicular to the plane of the drawing. The third curved portion 8 bends approximately 90° from the plane of the drawing downwardly to connect with the straight portion.

A keyhole slot 10 extends through a side wall of 20. the arcuate portion 6 and circumscribes an arc of approximately 110°.

The rigid guide conduit 5 is connected at its end opposite the keyhole slot to a flexible conduit 15 which has a straight portion 16 extending parallel to 25. and within the steering column 1.

A core member 17 extends through flexible conduit 15 as well as the rigid guide conduit 5 and has a tab 18 connected, at one end by crimping or other means. The tab 18 includes an extension 18' which 30-. extends through the keyhole slot 10. As seen in Figures 1 and 2 movement of the tab in the rigid

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arcuate portion 6 will cause the core member 17 to move in the arcuate portion 6 as well as in the curved por¬ tion 8 and straight portion 7 such that the arcuate or rotary motion of the tab 18 about the centre of cur- 5. vature of the arcuate portion i.e. about a central axis of the steering shaft 3, will result in linear motion of the core 17 within the straight portion 7 of the rigid guide conduit as well as within the flexible conduit 15.

10. Preferably the core member 17 has a flexible sheath 20 engaging the inner periphery of the curved portion 8 of the guide conduit, as shown in Figure 5, of the arcuate portion 6 when the tab extension is at the end of its rotational travel in the clockwise

15. direction with reference to Figure 2. Thus the sheath should extend a length equal to that of the combined lengths of the arcuate and curved portions 6 and 8. The sheath may comprise a plurality of individual tubular elements 21 as shown in Figure 3 to impart

20. flexibility to the sheath or could comprise a single member ribbed or slotted in a radial direction to give flexibility. By this construction any looseness bet¬ ween the core member 17 and the inner periphery of the curved and arcuate portion of the guide conduit caused

25. by spacing between the core and the inner peripheries is prevented thus eliminating any lost motion that might result from such spacing.

The core member 17 is preferably of the armored 30. strand type and is capable of transmitting compression and tension loads.

Referring to Figure 2 a gear shift lever 30 is shown connected with the tab extension 18' in order to provide the force necessary to move the tab extension within the slot 10. An indicia plate 31 is fixed with 5. respect to the steering column 1 shown in Figure 1 to provide an indication of the positioning of the gear shift lever to achieve the desired operating mode of an automatic transmission with which the core member 17 connects. An indicator, not shown, is operably con- 10. nected to the lever 30 to point to one of the selected indicia determined by positioning of the lever.

The device is designed such that movement of the operating lever out of "park" exerts a tension force on the core member 17. A tension force is desired rather

15. than a compression force since the heaviest load that is encountered in operation of an automatic trans¬ mission is movement of the gear lever from the "park" position. This feature is purposely designed into automatic transmissions as a safety measure to reduce

20. chance of inadvertent movement of the gear shift lever from the "park" position to an operating position.

It is seen that a device constructed according to the invention eliminates use of complicated linkages and because flexible conduits and cores are used, the 25. parts are light-weight and may easily collapse upon collapse of the steering column.

While the device is illustrated in the drawings as applied to a gear shift mechanism for an automatic transmission, the device could be used in other appli- 30. cations where it is necessary or desirable to translate a rotary motion to a linear motion.