Abstract:
A method for fitting a cylinder assembly into an internal combustion cylinder housing includes the steps of gripping the connected rod-pin-piston assembly with a gripper or clamp and lowering the connected rod-pin-piston assembly, gripped by the gripper or clamp, onto the head surface of the engine cylinder. The connected rod-pin-piston assembly is then inserted into the engine cylinder being thrust by an actuator passing through the gripper or clamp.

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is related to and claims priority, under 35 U.S.C. §119, from French patent application no. 98/12350 filed in the French Patent Office on Oct. 2, 1998, the entire contents of which are hereby incorporated by reference herein. 
     BACKGROUND OF THE INVENTION 
     1. Field of the Invention 
     The present invention generally relates to the mounting of a connected rod-pin-piston assembly in an internal combustion engine cylinder housing. 
     2. Discussion of Background 
     The mounting of connected rod-pin-piston assemblies in engine cylinders is carried out with a press on the engine assembly line. That operation, which simultaneously ensures placement of the pistons in the cylinders and tightening of the piston rings on the pistons, requires precise positioning of those different parts at the entrance to the cylinders before lowering the mounting press. 
     According to a known method, positioning and guiding elements called “necking cones” are placed at the entrance to the cylinders, which ensure tightening of the pistons on mounting. The arrangement of the necking cones on the cylinder housing, as well as that of the connected rod-pin-piston assemblies in the cylinder housing, cylinder by cylinder, before lowering of the press, are tedious manual operations, which affect the efficiency of the assembly lines. 
     The diversification of engines assembled on the same manufacturing site has led to a search for greater “flexibility” of production lines, for example, by simplifying the means of assembly or developing tools compatible with different families of engines, with a view to reducing the number of those tools and facilitating their use. 
     SUMMARY OF THE INVENTION 
     The present invention is aimed at making possible the use of the same equipment for mounting different types of connected rod-pin-piston assemblies, while simplifying the operations necessary. 
     The present invention proposes for that purpose that each connected rod-pin-piston assembly be gripped by a clamp and lowered by the clamp onto the head surface of the engine and then inserted into a cylinder under the thrust of a jack passing through the central hole of the clamp. 
     In accordance with the present invention, each clamp ensures tightening of the piston rings. 
     The clamp preferably has fingers movable radially inwardly in order to grip the connected rod-pin-piston assembly. 
     The present invention also concerns a device for mounting a connected rod-pin-piston assembly in an internal combustion engine cylinder housing. This device has at least one clamp with several fingers movable radially inwardly in order to grip the piston and simultaneously ensure tightening of the piston rings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWING FIGURES 
     Other characteristics and advantages of the present invention will clearly appear on reading the following description of an embodiment of the present invention, in relation to the attached drawings, in which: 
     FIG. 1 illustrates the known state of the art; 
     FIG. 2 schematically represents the device of the present invention; 
     FIG. 3 relates to a particular embodiment of a tightening clamp; and 
     FIG. 4 is a vertical cross-section taken along line IV—IV of FIG.  3 . 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring to FIG. 1, an engine housing  1  is schematically represented with a head surface  21  and four cylinders  2 , each intended to be fitted with a connected rod-pin-piston assembly A, the connected rod-pin-piston assembly A being comprised a rod  3 , a pin  4 , and a piston  6 , under the action of a mounting press  7   a  equipped with actuators  8 . As previously indicated, tightening of the piston rings  9  on the pistons  6  and mounting of the connected rod-pin-piston assemblies A, each connected rod-pin-piston assembly A being comprised of a rod  3 , a pin  4 , and a piston  6 , using a mounting press and actuator system, as shown in FIG. 1, require the operator to position a necking cone  11  on the opening O of each cylinder  2 , as well as the connected rod-pin-piston assemblies A, each connected rod-pin-piston assembly A being comprised of a rod  3 , a pin  4 , and a piston  6 , in the cones  11  before lowering of the actuators  8 . 
     When the same mounting press  7   a  is used for the assembly of different engines, it is necessary to arrange specific necking cones  11  for each engine. The diversification of engines on the same site therefore results in multiplying the number of parts references handled on the latter. 
     In accordance with the present invention, the mounting of connected rod-pin-piston assemblies A in the cylinder housing I is carried out mechanically, without necking cones  11 . Referring to FIG. 2, it is seen that the clamp  12  is capable of: supporting a connected rod-pin-piston assembly A being comprised of a rod  3 , a pin  4 , and a piston  6 ; guiding that connected rod-pin-piston assembly A opposite the opening O of a cylinder  2 ; and contracting the piston rings  9  on lowering of the jack  16 . The clamps  12 , suspended from the frame  13  of the mounting press  7  or fastened to the end of a robot (not represented), are provided with a center hole  14  allowing passage of a jack  16  and fingers  17 , which grip the pistons  6 . 
     FIGS. 3 and 4 show that the body  18  of the clamp  12  is supports a plurality of jaws  19  in a radially direction of the body  18  of the clamp  12 , and a finger  17  is fastened on each of the jaws  19 , bringing the piston rings  9  in contact, so as to tighten the piston rings  9  on the pistons  6 , on closing the clamp  12 . 
     Mounting of the connected rod-pin-piston assemblies A, each connected rod-pin-piston assembly A being comprised of a rod  3 , a pin  4 , and a piston  6 , in the cylinders  2  is carried out as follows. When the clamp  12  is in a high position, each connected rod-pin-piston assembly A is gripped by a clamp  12 , provided by a robot, or on a machine frame. The clamp  12  is then lowered on the piston  6 , which enters a center hole  14  in the body  18  of the clamp  12 . Closing of the clamp  12  on the piston  6  is carried out by the inward radial displacement of the jaws  19  and therefore, of the fingers  17 , which tighten the piston rings  9 . The clamp  12  holding the piston  6  is then lowered until the fingers  17 , still tightened around the piston  6 , come to rest on the top or head surface  21  of the housing  1 . Finally, actual mounting is carried out by lowering of the jacks  16 , which drive the pistons  6  inside each cylinder  2 . 
     The advantages of the present invention are numerous. In the first place, it makes it possible to mount connected rod-pin-piston assemblies of different types with the same equipment, for the clamps adapt themselves to the diameter of the pistons they grip, without having to handle accessories, such as specific necking cones, for each engine. Furthermore, those clamps have a triple function, since they are capable of gripping the pistons, tightening the piston rings and positioning the connected rod-pin-piston assemblies at the cylinder entrance, before the actual mounting operation. 
     The elimination of manual positioning of the necking cone and piston makes it possible to reduce mounting cycle times considerably. 
     Finally, it is to be noted that the number and shape of the fingers of the clamp or shape of the jaws can be very variable without thereby departing from the scope of the present invention, the working example illustrated by the figures not being limitative in that regard.