Arrangement for connecting a rod end to a headed pin and method of manufacture

Abstract

An arrangement and method of manufacture for providing a connection between one end of a control rod and a headed pin includes a hard plastic housing having a pin receiving cavity defined therein, the housing overmolded over the rod end and a soft elastomeric vibration isolator to hold the same together without assembly clearances or subjecting the vibration isolator to direct pressure from the pin to avoid excessive lash in the connection. Retention prongs are integrally molded and configured to engage the head of the pin when inserted in the cavity to be deflected to allow assembly and thereafter resist extraction, with the insertion forces much lower than the extraction force.

Description

BACKGROUND OF THE INVENTION

This invention concerns rod end terminal connections commonly used to connect control rods to pins mounted to automobile transmission levers and the like to enable shifting of the transmission by the driver of the automobile. The pin is retained in a housing by a ball feature head on the pin snap fit to retention features on the housing. It has become standard practice to interpose a vibration isolator between the connected rod and pin to prevent vibrations from being felt by the driver when grasping a shifter or other member. See U.S. Pat. No. 4,581,953 for an example of such a connection.

The vibration isolator is usually constructed of a soft compressible material and excessive lash can result if the isolator material is directly contacted by the pin.

Such connections have been provided by assembling several parts together, and the necessary clearances for assembly also contribute to excessive lash at the connection.

The cost of manufacturing such linkages typically is high due to the need to assemble several components, and the need to insure that proper assembly of the components has been accomplished.

Another difficulty is encountered in designing the usually snap fit assembled pin and rod connection so that the force to assemble the connection must be low while the force resisting disconnection of the components must be much higher.

It is the object of the present invention to provide an arrangement for providing a connection between a pin and control rod including a vibration isolator which minimizes lash between the connected components.

It is a further object to provide such an arrangement which can be manufactured at low cost.

It is yet another object to provide a snap fit pin-rod connection in which a desired greater separation force and lesser assembly force can be easily designed for.

SUMMARY OF THE INVENTION

These and other objects which will become apparent upon a reading of the following specification and claims are achieved by an arrangement for establishing a rod end terminal connection having a vibration isolator of minimal thickness interposed between the rod and an overmolded minimally compressible hard plastic housing capturing the rod end and a vibration isolator interposed between the rod end and a pin receiving cavity defined by a hard plastic structure enclosed within the housing. Preferably the vibration isolator is itself overmolded onto the rod end, received in grooves in the rod and to be securely locked thereto. The hard plastic defined cavity is configured to receive the pin and a plurality of integral arcuate prongs are arranged about the inside of the cavity. The prongs are readily deflectable outwardly engagement of the head of the pin with sloping prong surfaces to accommodate insertion of the pin, but pin movement out is resisted by flat prong ends which requires application of a desired high extraction force to deflect the prongs and allow removal of the pin.

The overmolding of the hard plastic housing eliminates assembly of separate parts as well as eliminating clearances and lash resulting from having separate parts. The housing opening has an overlying web blocking entrance of the pin into the cavity from the wrong side to insure insertion of the pin into the housing from the prior side.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of an arrangement for establishing rod end head pin connection according to the invention.

FIG. 2 is a plan view of the arrangement shown in FIG. 1 with a fragmentary view of a rod end.

FIG. 3 is a vertical sectional view taken through the rod end terminal connection shown in FIG. 1.

FIG. 4 is a horizontal sectional view taken through the rod end terminal connection shown in FIG. 1.

FIG. 5 is a fragmentary partially sectional perspective view from one side of the connection and mated pin shown in FIGS. 1-4.

FIG. 6 is a fragmentary partially sectional endwise perspective view of the connection shown in FIGS. 1-5.

FIG. 7 is a fragmentary plan view of a connection with a mating pin according to a second embodiment of the invention.

FIG. 8 is a view of a vertical section through the connection shown in FIG. 1.

FIG. 9 is a plan view of an assembled inner core piece and vibration isolator components included in the connection shown in FIGS. 7 and 8.

FIG. 10 is a side elevational view of the assembled inner piece core and vibration isolator components shown in FIG. 9.

FIG. 11 is a perspective view of the inner core and assembled isolator components shown in FIGS. 9 and 10.

FIG. 12 is a perspective fragmentary view of the rod and terminal connection and mating pin shown in FIGS. 7 and 8.

DETAILED DESCRIPTION

In the following detailed description, certain specific terminology will be employed for the sake of clarity and a particular embodiment described in accordance with the requirements of 35 USC 112, but it is to be understood that the same is not intended to be limiting and should not be so construed inasmuch as the invention is capable of taking many forms and variations within the scope of the appended claims.

Referring to the drawings, and particularly FIGS. 1-6, the present invention provides an arrangement for establishing a connection between a headed pin 10 and one end of a steel control rod 12. Such connections are commonly used to couple a transmission control rod to an automotive transmission lever by a pin allowing relative rotation. Other control linkage systems for automotive and other applications widely use such connections which allow a changing angle of the control rod on the pin as it is advanced retracted.

This connection includes a thin walled (approximately 1 mm thick) soft elastomeric vibration isolator 14 preferably molded in place onto the one end of the control rod 12, with a recess 16 on the one end of the rod 12 keying the vibration isolator 14 to insure retention thereon. The recess 16 also forms an annular feature 17 in the vibration isolator. The vibration isolator 14 could also be separate molded and assembled onto the one end of the control rod 12 (a suitable material is Bayer Desmopan 453 polyester polyethylene based grade) Shore hardness scale 53D (ASTM D2240).

A pin receiver housing 18 is molded over the vibration isolator 14 and projects in a lengthwise direction away from the one end of the rod 12 to offset a hard plastic structure defining a pin receiving cavity 20 extending in a normal direction from the longitudinal axis of the control rod 12.

A portion of the housing 18 is received into the annular recess 17 formed in the vibration isolator 14 to be positively keyed thereto for secure retention.

The housing 18 is molded from a hard plastic such as Dow Vydyne R533 (Nylon 66% graphite filled (33%), Rockwell harness scale M95 (ASTM D785).

A pair of pin retention features comprising arcuate prongs 22 are integrally formed on opposite sides of the cavity 20. Each prong 22 includes an axially extending base wall 24 spaced inwardly from the inside of the housing 18 to create a space allowing a radially outward deflection thereof.

A radially inward projecting lip portion 26 extends from the free end of the base wall 24, having a sloping undersurface 28 and a flat end surface 30 at the top as viewed in the drawings.

The lower end of the cavity 20 is open while a web 32 extends there across at the top to provide an orientation feature insuring correct assembly with the pin 10 able to be inserted only from below as seen in the drawings.

The pin 10 has a spherical head 34 which when inserted into the cavity 20 deflects the prongs 22 radially outward facilitated by the sloping undersurface 28 of the prongs being cammed outwardly by the spherically curving head 34. Integral ribs 23 limit outward deflection of the prongs 22.

After the head 34 is inserted sufficiently, the head 34 passes lips 26 of the prongs 22 allowing the prongs 22 to snap back to present the flat end face to the undersurface of the head 34.

A flange 38 on the pin 10 limits further insertion travel of the pin 34 by engaging the bottom 40 of the housing 18.

The insertion force required to install the pin 10 is much less than the force necessary to remove the pin 10 as a result of the sloping undersurface 28 and the flat end face 30. By varying the thickness of the wall 24, any particular insertion force maximum and extraction force minimum can be designed for to meet the application requirements. The wall 24 is placed in bending by the camming out of the prongs 22 as the ball head 34 is inserted.

The manufacturing process involves molding the vibration isolator 14 to the one end of the rod 12.

The manufacturing steps are as follows:

This subassembly is then placed in a mold and housing 18 is overmolded around the isolator-rod subassembly, the housing 18 having a portion located at one end of the rod 12 and formed with a socket opening with radially inwardly projecting engagement prongs for securing the pin. The housing 18 in being molded from a hard plastic material, a low installation force for installing the pin can be achieved compared with much higher extraction forces required to separate the housing 18 from the pin 10.

The specific manufacturing process steps are as follows:

The vibration isolator 14 is installed around the end of the steel rod 12. The groove 16 in the end of the rod 12 will match up to an inner ridge on the isolator. The vibration isolator 14 is molded around the end of the steel rod 12 with the groove and ridge matching.

Once the vibration isolator 14 rod 12 subassembly is made, molding of the final terminal assembly takes place. The vibration isolator 14 rod 12 subassembly is placed in the mold into a predetermined position. No special position for orientation is needed. The prongs 22 and load feature of the housing 18 is then molded to create the final assembly. This molding process interlocks the vibration isolator 14 rod 12 subassembly with the newly molded housing 18.

This connection and method provides several advantages. The first is that the hard plastic housing 18 with engagement prongs 22 comprise a socket contacting the pin 10, allowing the design of the prongs 22 to set the amount of installation and extraction force desired. By changing the prong design, i.e., the thickness of the wall, the amount of installation load required to secure the pin 10 can be reduced to meet any requirements and still maintain the required minimum extraction force.

The second advantage is that by molding the housing 18 around the vibration isolator 14 and steel rod end, this will provide increased strength to the rod end assembly and ensure that the housing 18, vibration isolator 14, and steel rod 12 are securely assembled. This design will also interlock these components to eliminate any tolerance gaps between individual parts. Prior designs had the possibility for tolerance gaps between parts, which will cause free play in the system known as “lash”.

The third advantage is that the vibration isolator 14 is wrapped around the steel rod 12 to avoid direct contact with the pin 10. The vibration isolator 14 is molded with a small cross section wall to lower the thickness of material subject to compression. This will lower system lash and while still maintaining adequate vibration dampening capabilities.

The fourth advantage is a reduction in manufacturing cost. By molding the housing 18 over the vibration isolator/steel rod subassembly there is a reduction in cost for manufacturing the connection.

The fifth advantage is obtained by the addition of the orientation feature 36 to the housing 18. By adding this feature integrally the housing 18 can only go onto the pin 10 in one direction. Previously this was done by installing a separate component, increasing the cost of manufacture.

This design will make it easier to install on the vehicle, reduces cost, and reduces the number of parts in the assembly.

The second embodiment is shown in FIGS. 7-12, in which a hard plastic housing 38 is directly molded to one end of the control rod 12.

The ring shaped vibration isolator 40 is assembled onto a generally cylindrical hard plastic core piece 42 separately molded. The housing 38 is molded over the vibration isolator 40. Thus, the vibration isolator 40 does not directly contact the pin 10.

The core piece 42 has a central pin receiving cavity 46 formed with inwardly facing deflectable prongs 44 and orientation feature 48 as in the first described embodiment.

A ridge 43 on the core piece 42 forms grooves 45 matching grooves 47 on the vibration isolator 40 on the core piece 42 and, together with a ridge 41 on the vibration isolator 40, these ensure mutual retention to the overmolded housing 38.

The vibration isolator 40 is installed around the inner core piece 42. The grooves 45 match up on both parts. The vibration isolator 42 is fully assembled around the inner core piece 42 and the grooves matched. Direction does not matter since the vibration isolator 42 is symmetrical and will go on either direction.

The inner core piece subassembly is placed in the mold along with the groove end of the steel rod 12. The inner core piece subassembly is installed on a special pin in the mold. This special pin correctly positions the inner core piece subassembly so that the load path feature of the inner core piece 42 is in an axial line with the steel rod 12. This will insure that the contact prongs 44 will be positioned 90 degrees to the steel rod 12.

Once the inner core piece subassembly is in place, the steel rod 12 is placed in the mold. The rod 12 is positioned so that the rod end contacts the ridge 43 vibration isolator 40. This will serve as a position stop for the steel rod 12. This stop feature will make it easier for the operator to properly place the steel rod 12 for the final molding.

Once the steel rod 12 and the inner core piece subassembly are correctly in place, the outer housing 38 is molded over these two other components. This molding process interlocks the inner core piece subassembly and the steel rod to form the final terminal rod assembly.

Claims

1. An arrangement for connecting a one end of a control rod to a headed pin to enable driving of said pin by motion of said control rod, in combination with said control rod and said headed pin, comprising: a housing made of a hard plastic and defining a pin receiving cavity, with one or more retention features projecting into said cavity and engaging said headed pin when inserted therein so as to be retained therein; a vibration isolator made of an elastic material softer than said housing, said vibration isolator fit over said one end of said control rod; and said housing overmolded onto said vibration isolator join together said housing, said one end of said rod, and said vibration isolator.

2. (canceled)

3. (canceled)

4. (canceled)

5. The arrangement according to claim 1 wherein said one end of said rod has a groove formed therein, and said vibration isolator is fit into said groove, and said housing overmolded onto an annular feature formed on the exterior of said vibration isolator.

6. The arrangement according to claim 5 wherein said vibration isolator has a wall thickness on the order of one millimeter.

7. (canceled)

8. (canceled)

9. (canceled)

10. The arrangement according to claim 1 wherein said one or more retention features comprise one or more prongs projecting into said cavity and having radially deflectable portions able to be deflected by a headed portion on said pin and allow passage into said cavity, said head of said pin after passage into said cavity.

11. The arrangement according to claim 10 wherein said prongs are each formed with an axially extending base wall radially spaced from a core structure portion and also having a lip, projecting inwardly from said wall, and having a sloping under surface to be engaged by said head on said pin to cause said radial deflection of said associated prong, and a flat surface engaging said head after said pin head has been inserted past said prongs to retain said pin in said cavity.

12. The arrangement according to claim 1 further including a web integrally molded into said housing extending over said cavity on one side to prevent insertion of said pin from said one side.

13. A method of constructing a driving connection between one end of a control rod and a headed pin, comprising the steps of: molding a hard plastic housing to extend over said one end of said control rod; forming a cavity in our within said housing offset from said one end of said rod and configured to receive said headed pin; forming at least one feature within said cavity engaging said headed pin upon insertion therein to retain the same; interposing an elastomeric vibration isolator softer than said hard plastic housing between said hard plastic housing defining said cavity and said one end of said rod and overmolding said housing onto said vibration isolator when molding said housing to thereby join together said housing, said one end of said rod and said vibration isolator.

14. The method according to claim 13 wherein said step of forming said cavity is included in the step of molding said housing.

15. The method according to claim 14 further including the steps of locating said vibration isolator on said one end of said rod and overmolding said housing over said vibration isolator on said rod.

16. The method according to claim 15 further including the step of molding said vibration isolator as a tubular structure disposed over said one end of said rod prior to overmolding said housing onto said vibration isolator.

17. (canceled)

18. The method according to claim 16 wherein in said step of molding said vibration isolator to said one end of said rod, said vibration isolator is formed with a thin wall on the order of one millimeter in thickness.

19. The method according to claim 13 wherein said step of forming at least one retention feature comprises the step of molding a plurality of integral prongs in said hard plastic housing extending radially inward into said cavity configured to engage a head portion of said pin and be deflected radially outward thereby to allow passage of said head portion and to thereafter engage said head portion to retain the same in said cavity.

20. The method according to claim 19 wherein said prong molding step includes forming a sloping under surface on said prongs to aid in producing radial outward deflection by passage of said pin head portion, and a flat surface on the end thereof engaging said pin head portion to resist extraction whereby a much greater force is required for extraction than for insertion of said pin.