As it unexpectedly turned out, the required forming of the characteristics is insured by the new embodiment of the elastomeric shock absorber in which the connecting ports, communicating spaces at the front and at the back of the piston head, are connected with the cylindrical surface of the piston head with the application of a channel in which there is at least one groove in the inner surface of the casing. This groove together with the cylindrical surface of the piston head forms a flow chamber, but shaped as a solid of revolution, and the solid being selected from the group comprising a cone, a ring, a torus and any combination of the mentioned solids. It is an advantage of the present invention to enable the manipulation of the shock absorber performance characteristic over a wide range, which is achieved by the appropriate choice of the cross-section of the aperture and that of the channel connecting it with the cylindrical surface of the piston head, and also by the appropriate choice of the shape of the flow chamber.
FIG. 1 is a longitudinal section of a compressed elastomeric shock absorber equipped with two flow chambers, one of which has a shape of a part of a torus and the other has a shape of a ring;
The elastomeric shock absorber as depicted in FIG. 1 includes a cylindrical casing 1, which is tightly closed from one side by means of a closure member 2 and from the other side by means of a stuffing-box 3 (end cap; end seal, etc. The interior of the casing forms a chamber 4 filled with compressible and precompressed elastomer, in which a piston rod 5 is immersed having a piston head 6 mounted thereon. The piston head 6 is formed of a solid of revolution with a diameter smaller than the inner diameter of the casing. The said piston rod is guided outside through the stuffing-box provided with sliding means 7 and sealing means 8. In the casing the piston rod is slidably mounted inside a guide means 9 provided with flow ports 10, the said guide means 9 being located out of reach of the piston head. Supporting the piston rod in the casing inside the guide bar, located near the bottom section, increases the resistance of the piston rod to buckling and insures the centric guiding of the piston head in the casing with some backlash between the piston head and the casing's wall. On the front surface of the piston head, in a section facing the guide means there is provided a cavity 11, in which a mobile annular member 12 is located, the said mobile member being closed by a ring or stop block 13. Moreover, the head is equipped with connecting ports 14, which communicate the said cavity with the second front surface of the head, the said ports forming an orifice 15 at the section facing the stuffing-box. The connecting ports merge into the cylindrical surface 17 of the piston head through the channel 16. On the inner surface 18 of the casing, in the area of the terminal position of the head, there are provided two grooves 19 and 20, which form two flow chambers: one shaped as a ring, the other shaped as part of a torus.
The elastomeric shock absorber according to the invention operates in the following manner: with no impact forces imposed, the piston rod is located in a casing filled with a precompressed elastomer, the said piston rod being at its initial rest position. The impact force exceeding a predetermined value imposed on the piston rod so as to cause the latter to move inwardly in the casing (1) from the initial position toward the terminal position and the said movement proceeds relative to the increase of said impact force. During the movement of the piston rod 5, directed to the inside of the shock absorber, the movable member 12 is pressed, as an impact of the elastomer's pressure, upon the outlet of the connecting port 14 and thus the flow of elastomer is stopped. This stage of the piston rod's movement is accompanied by elastomer flow only between the cylindrical surface 17 of the piston head and the inner surface 18 of the casing. According to the invention, as the piston rod returns to its normal rest position there proceeds a known flow of the elastomer from one section of the chamber 4 to its other section through the aperture 14, while the said flow is limited by the orifice 15. Simultaneously the elastomer is displaced through the flow chamber 19, 20, 21 or 22 provided as peripheral grooves on the surface 18 of the casing; or through a flow chamber 24 shaped as a slot on the inner surface 18 of the casing. From the flow chamber the elastomer passes to the connecting port 14 directly or, in another variant of the invention, by means of the channel 16. At this stage of the piston rod movement the elastomer emerges from the connecting port 14 into a cavity 11 flowing by a mobile member 12 and therefrom to the other section of the casing's chamber 4.