JPH0230230Y2 - - Google Patents

Description

[Detailed explanation of the idea]

[Industrial Application Field] The present invention relates to a device for automatically assembling a piston ring into a ring groove of a piston of an internal combustion engine, a compressor, or the like. [Prior Art] Conventionally, there is a device shown in FIG. 4 that automatically inserts a piston ring into a ring groove of a piston. In this device, a large number of piston rings 2 are fitted into an expansion shaft 16 whose tip has an outer diameter larger than that of the piston 4, and the piston 4 is inserted into a piston head insertion hole 8 formed at the tip of the expansion shaft 16. Insert the piston ring 2 into the ring groove 13 of the piston 4 by pushing out the piston ring 2 from the tip of the expansion shaft 16 with the extrusion sleeve 11 that fits into the expansion shaft 16. It is something to do. Then, the distal end surface 1 of the expansion shaft 16
8 and the distal end surface 20 of the extruded sleeve 11 form a plane perpendicular to the axial direction. [Problems to be Solved by the Invention] In such a conventional device, the posture of the piston ring 2 on the expansion shaft 16 is changed as shown in FIGS. Buckling occurs due to expansion, and the abutment portion 9 protrudes more axially than other portions. As a result, the moment the piston ring 2 comes off the expansion shaft 16, it often comes off the abutment portion 9. Furthermore, at the moment of detachment, it is rare for both of the abutments 9 to come off at the same time, and one of the abutments 9 will come off first. The self-restoring force of the piston ring 2 returning from the expanded state to the free state varies depending on the material and shape of the piston ring 2, but if this restoring force is high, the piston ring 2 may break. This breakage is due to the impact force etc. when the piston ring 2 is momentarily released from the expansion shaft 16, but we investigated the ring part that first comes off at the moment the piston ring 2 comes off the expansion shaft 16 and the actual frequency of breakage. The results are shown in Table 1.

[Means for solving problems]

The configuration of the present invention to achieve the above object includes an expansion shaft that has an outer diameter larger than the outside diameter of the piston at its tip and a piston head insertion hole formed in the tip, and that fits into the expansion shaft. A piston ring assembling device comprising a sleeve for pushing out a piston ring fitted on an expansion shaft, characterized in that at least one of the front end surface of the expansion shaft and the front end surface of the extrusion sleeve is an inclined surface. [Operation] When the distal end surface of the expansion shaft is an inclined surface, if the abutment part of the piston ring is positioned on the protruding distal end side of the expansion shaft, the piston pushed out by the extrusion sleeve can be The ring comes off the expansion axis from a part 180° away from the abutment. In addition, when the tip end surface of the extrusion sleeve is an inclined surface, if the abutment part of the piston ring is located on the opposite side of the extrusion sleeve's protruding tip, it is possible to Similarly to the above, the piston ring comes off the expansion axis from a part 180 degrees away from the abutment. [Embodiment] Figure 1 shows an embodiment of the present invention, in which the expansion shaft 1
is a small-diameter shaft portion 3 that is slightly larger than the inner diameter of the piston ring 2, a large-diameter shaft portion 5 that is slightly larger than the outer diameter of the piston 4 disposed at the tip, and a combination of the large-diameter shaft portion 5 and the small-diameter shaft portion 3. It consists of a tapered shaft portion 6 in between.
The distal end surface 7 of the large diameter shaft portion 5 forms an inclined surface, and the step h (see FIG. 2) is preferably 0.1 to 0.5 mm. If it is less than 0.1 mm, the piston ring 2 will come off unstable, and if it exceeds 0.5 mm, the piston ring 2 will come off naturally when left unattended, which is not preferable. Further, the large diameter shaft portion 5 is provided with a piston head insertion hole 8 into which the head of the piston 4 is inserted in the axial direction from the distal end surface 7. A piston ring 2 is attached to the small diameter shaft portion 3 of this expansion shaft 1.
Many can be fitted. At this time, piston ring 2
is arranged so that the abutment portion 9 is located toward the protruding tip portion 10 of the expansion shaft 1. Expansion axis 1
An extrusion sleeve 11 is fitted into the small diameter shaft portion 3 of the extrusion sleeve 11, and the distal end surface 12 of the extrusion sleeve 11 does not form an inclined surface like the distal end surface 7 of the expansion shaft 1.
Forms a plane perpendicular to the axial direction. The piston ring 2 is pushed and moved on the expansion shaft 1 by the extrusion sleeve 11 fitted to the expansion shaft 1. As a result, the piston ring 2 is gradually expanded at the tapered shaft portion 6, and expanded to a larger extent than the outer diameter of the piston 4 at the large diameter shaft portion 5. Then, the piston ring 2 pushed out from the distal end surface 7 of the expansion shaft 1 by the extrusion sleeve 11 is such that the wall surface 14 of the ring groove 13 of the piston 4 is flush with the distal end surface of the distal end portion 10 from which the expansion shaft 1 protrudes. The piston ring 2 is inserted into the ring groove 13 of the piston 4 inserted into the piston head insertion hole 8 of the expansion shaft 1 so that the piston ring 2 has a self-restoring force. At this time, the piston ring 2
As shown in the figure, since the distal end surface 7 of the expansion shaft 1 forms an inclined surface, it comes off the expansion shaft 1 from a portion 15 that is 180 degrees away from the abutment portion 9. For this reason, the piston ring 2 at the moment it comes off the expansion shaft 1
No more breakage. FIG. 3 shows another embodiment of the present invention, which differs from the one in FIG. This point is a vertical surface, and the tip end surface 20 of the extruded sleeve 19 is an inclined surface. The step h of the slope is preferably 0.1 to 0.5 mm, similar to the slope of the expansion shaft 1 shown in FIG. 1 above. Therefore, if the piston ring 2 is fitted onto the expansion shaft 16 so that the abutment part 9 of the piston ring 2 is located at a part 22 that is 180 degrees away from the protruding tip part 21 of the extrusion sleeve 19, the extrusion can be performed. When the piston ring 2 is being pushed out by the sleeve 19, the piston ring 2 is moved from the ring section 15 located toward the protruding tip section 21 of the extrusion sleeve 19, that is, the section 15 that is 180° away from the mating opening 9. They are pushed out in advance. Therefore, like the one in FIG. 1 above, the piston ring 2 comes off on the expansion shaft 16 from the part 15 that is 180 degrees away from the abutment 9, so the piston ring 2 at the moment it comes off from the expansion shaft 16. This eliminates the possibility of breakage. In the above example, either the distal end surface of the expansion shaft or the distal end surface of the extrusion sleeve is an inclined surface, but both distal end surfaces may be formed as an inclined surface. [Effects of the invention] As explained above, according to the invention, at least one of the distal end surface of the expansion shaft and the distal end surface of the extruded sleeve is made into an inclined surface, so that the piston ring is not disposed at the abutment when the piston ring is assembled. Since the piston ring can be disengaged from the expansion axis from a part 180 degrees away from the piston ring, breakage of the piston ring when assembling the piston ring is eliminated.

[Brief explanation of the drawing]

Fig. 1 is a sectional view showing one embodiment of the present invention;
3 is a sectional view showing another embodiment of the present invention, FIG. 4 is a sectional view showing a conventional example,
FIG. 5 is a sectional view of the main part, and FIG. 6 is a plan view of the main part. 1 and 16 are expansion shafts, 2 is a piston ring, 4 is a piston, 5 and 17 are large diameter shaft parts, 7, 12, 1
8, 20 are the tip surfaces, 8 is the piston head insertion hole, 9
11 and 19 are extruded sleeves, and 13 is a ring groove.

Claims (1)

[Scope of utility model registration request] The expansion shaft has an outer diameter larger than the outer diameter of the piston at its tip and has a piston head insertion hole formed in the tip, and a sleeve that fits on the expansion shaft and pushes out the piston ring fitted on the expansion shaft. A piston ring assembling device comprising: at least one of the distal end surface of the expansion shaft and the distal end surface of the extrusion sleeve is an inclined surface.