METHOD FOR ASSEMBLING A VEHICLE GEAR LEVER, AND A GEAR LEVER OBTAINED BY SAID METHOD

Abstract: The method enables a rod (2) to be fixed to a dog (4) of a gear lever (1), and consists essentially of performing the following operations in succession: - forming in the rod (2) a recess (6) having a flat surface (7); - forming in the dog (4) a comb-shaped end portion (8) with two parallel teeth (9, 10); - resting said end portion (8) on the surface (7) of the recess (6); and - welding each tooth (9, 10) to the rod (2) along the edges of the tooth so as to form respective weld seams (11, 12; 13, 14) perpendicular to the longitudinal axis of said rod (2).

Description: This invention relates to a method for assembling a vehicle gear lever, and a gear lever obtained by said method. More particularly, the invention relates to a method for fixing together two of the components of said lever, namely the support rod for the gear positioning fork and the rod control dog. A product of the aforesaid type consists essentially of a metal rod and a metal dog, and is usually produced by inserting the rod through a suitable seat provided in the dog, and then connecting the two parts rigidly together by means of a screw. Generally, the dog is produced by casting, so that the resultant product has a heavy and bulky structure, although it has good operating characteristics. In order to give the aforesaid product a structure which can be produced using less material and a less costly manufacturing procedure, systems have been proposed for fixing said parts together by longitudinally welding the dog to the rod. Such welding however results in rotational deformation of the dog about the rod, because of the shrinkage which occurs on welding. A welding system has also been proposed in which the connection between the rod and dog is obtained by making two longitudinal welds simultaneously along the adjacent peripheral regions of the rod and dog by means of two laser beams. However, this latter system is difficult and costly to implement, in that the particular geometry of the parts to be fixed together makes it very complicated to coordinate the two said laser beams. The object of the present invention is to provide a method for assembling a gear lever such as to produce a gear lever which obviates the drawbacks (bulk, weight, cost etc.) connected with the aforesaid known methods and current levers. Said object is attained according to the present invention by a method for fixing together a rod and a dog of a vehicle gear lever, characterised by comprising the following operations in succession: forming in said road a recess having a flat surface parallel to the longitudinal axis of said rod to define a seat for housing said dog; forming in said dog a comb-shaped end portion comprising at least two parallel teeth; resting said end portion of said dog on said flat surface of the recess in said rod, with said parallel teeth positioned perpendicular to the longitudinal axis of said rod; and welding each tooth to said rod along peripheral regions of contact between the tooth and rod which lie in a plane perpendicular to the longitudinal axis of said rod. The present invention also relates to a vehicle gear lever of the type provided with a rod and a dog fixed to the rod, characterised in that said rod is provided with a recess having a flat surface parallel to the longitudinal axis of said rod, and said dog is provided with a comb-shaped end portion with at least two parallel teeth; said end portion of said dog resting on said flat surface of the recess in said rod and being fixed to this latter by a plurality of welds, each of which extends along a respective peripheral region of contact between the tooth and rod and lies in a plane perpendicular to the longitudinal axis of said rod. The present invention will be more apparent from the description of a preferred embodiment thereof given hereinafter with reference to the accompanying drawing, in which: Figure 1 is an exploded view of a portion of a gear lever before assembly; Figure 2 is a plan view to an enlarged scale of a detail of the lever of Figure 1 after assembly; and Figure 3 is a section on the line III-III of Figure 2. In Figure 1, the reference numeral 1 indicates overall a portion of a vehicle gear lever of the type comprising essentially a cylindrical rod 2 supporting a fork 3 which when in use engages a respective gear selection sleeve (not shown), and a dog 4 the purpose of which is to control the movements (both longitudinal and rotational) of the rod 2 when in use. According to the present invention, the rod 2 is provided with a recess 6 having a flat surface 7 parallel to the longitudinal axis of the rod, and the dog 4 is provided with an end portion 8 shaped as a comb with at least two parallelepiped teeth 9, 10 extending parallel to each other. When in use (see Figures 2 and 3), the end portion 8 of the dog 4 rests on the flat surface 7 of the recess 6 in the rod 2, and is fixed to this latter by a plurality of welds 11, 12 and 13, 14 each of which extends along a respective peripheral region of contact between the teeth 9 and 10 and the rod 2 and lies in a plane perpendicular to the longitudinal axis of the rod 2. The method for assembling the portion 1 of said gear lever comprises essentially the following operations in succession: forming in the rod 2 the recess 6 provided with the flat surface 7 parallel to the longitudinal axis of the rod 2, so as to define a seat for housing the end portion 8 of the dog 4; forming in said dog 4 the said comb-shaped end portion 8 with the two parallel teeth 9, 10; resting the end portion 8 of the dog 4 on the flat surface 7 of the recess 6 in the rod 2, taking care to position the parallel teeth 9, 10 perpendicular to the longitudinal axis of the rod 2; and welding each tooth 9, 10 to the rod 2 along peripheral regions of contact between the tooth and rod which are perpendicular to the longitudinal axis of the rod, so as to form the transverse welds 11, 12 and 13, 14 as shown in Figure 2. Conveniently, the aforesaid welds can be formed under high-density energy conditions by using for example laser, electron beam or miniplasma technology. The advantages of the aforesaid method and of the gear lever obtained by said method are apparent from an examination of their characteristics. In this respect, by welding along the lines 11, 12 and 13, 14 indicated in Figure 2, the shrinkages caused by welding result essentially in a transverse approach of the dog 4 towards the rod 2 (in the direction indicated by the arrow A in Figure 3), without inducing any rotation of one part relative to the other (for example in the direction indicated by the arrow B in Figure 3). The "double toothed" geometry of the end portion 8 of the dog 4 enables the total length of the welds and thus the mechanical strength of the final product to be increased. It is apparent that as there is no restriction on making welds successively, the aforesaid difficulties resulting from the need to make two welds simultaneously do not arise. Finally, it is apparent that modifications be be made. For example, the relative shapes of the two described parts could be different from that shown (in particular the teeth of the end portion 8 of the dog 4 could be more than two in number), provided the concept of making the welds transversely to the longitudinal axis of the said rod 2 is not modified.

Claims: A method for fixing together a rod (2) and a dog (4) of a vehicle gear lever (1), characterised by comprising the following operations in succession: forming in said rod (2) a recess (6) having a flat surface (7) parallel to the longitudinal axis of said rod (2) to define a seat for housing said dog (4); forming in said dog (4) a comb-shaped end portion (8) comprising at least two parallel teeth (9, 10); resting said end portion (8) of said dog (4) on said flat surface (7) of the recess (6) in said rod (2), with said parallel teeth (9, 10) positioned perpendicular to the longitudinal axis of said rod (2); and welding each said tooth (9, 10) to said rod (2) along peripheral regions of contact (11, 12, 13, 14) between the tooth (9, 10) and rod (2) which lie in a plane perpendicular to the longitudinal axis of said rod (2). A method as claimed in claim 1, characterised in that said welding is carried out using a high-density energy source. A method as claimed in claim 2, characterised in that said high-density energy source is chosen from one of the following: laser, electron beam, miniplasma. A vehicle gear lever (1) of the type provided with a rod (2) and a (4) dog fixed to the rod, characterised in that said rod (2) is provided with a recess (6) having a flat surface (7) parallel to the longitudinal axis of said rod (2), and said dog (4) is provided with a comb-shaped end portion (8) with at least two parallel teeth (9, 10); said end portion (8) of said dog (4) resting on said flat surface (7) of the recess (6) in said rod (2) and being fixed to this latter by a plurality of welds (11, 12, 13, 14), each of which extends along a respective peripheral region of contact between the tooth (9, 10) and rod (2) and lies in a plane perpendicular to the longitudinal axis of said rod (2). A lever as claimed in claim 4, characterised in that each said tooth (9, 10) has an essentially parallelepiped structure. A lever as claimed in claim 5, characterised in that said welds (11, 12, 13, 14) extend along opposing edges of said teeth (9, 10) of parallelepiped structure.

Inventors: BRUNO, ALFONSO, RABINO, EDOARDO, RAVIZZA, RENATO
Applicants: FIAT AUTO S.P.A.
Application year: 1988
Main classification: G05G3
IPC codes: F16H63