Diaphragm-piston shock absorber

Abstract

FIELD: mechanical engineering.SUBSTANCE: diaphragm-piston shock absorber contains a ring-shaped hydraulic cylinder and a piston in the hydraulic cylinder, combined with an adjustable diaphragm, providing oscillations of the rod with the piston with an adjustable resistance force of the working fluid from free oscillations to complete fixation of the position of the piston in the hydraulic cylinder.EFFECT: adjustability of the elasticity coefficient of the shock absorber and damping and the ability to fix two movable devices relative to the longitudinal axis of rotation.1 cl, 3 dwg

Description

[0001] The proposed invention relates to the field of mechanical engineering, in particular to the automotive industry, and can be used in two- and multi-link machines to improve the controllability of trailer links, as well as in pumping devices in the oil producing industry and in microelectromechanical systems (MEMS).

[0002] The closest to the proposed invention is a piston shock absorber containing a hydraulic cylinder, a hydraulic cylinder base, a hydraulic cylinder piston, a piston rod, seals on the ends of the hydraulic cylinder, working fluid in the hydraulic cylinder, a hydraulic cylinder base, and elements of detachable mechanical connections on the outer ends of the piston rod for power control [Vasilchenkov V.F. Military vehicles and tracked vehicles. Fundamentals of chassis design. - Rybinsk: Publishing House of JSC "RDP" - ARP, 1996. - 496 p. P. 383].

[0003] The well-known shock absorber operates as follows. When a longitudinal load from the movable drive mechanism is applied to the piston rod, the fluid in the first chamber of the hydraulic cylinder is compressed and flows through the spool into the second chamber. The increasing volume of the working fluid in the second chamber moves the piston in the second chamber, behind which is a gas chamber. The elastic compression of the gas dampens (softens) the force of the piston rod in the first chamber of the hydraulic cylinder. When the piston rod position needs to be fixed, the spool closes, and the piston rod is fixed in the position at the moment the spool closes. The incompressible working fluid maintains the position of the piston rod in the first chamber and, accordingly, the movable drive mechanism connected to the piston rod.

[0004] The disadvantage of the known technical solution is the non-adjustability of the elasticity coefficient of the shock absorber, the impossibility of damping and fixing the position of two devices with relative rotational movement, for example, damping and fixing relative to the longitudinal axis of the links of two-link tracked vehicles in any steady position at any time.

[0005] The technical solution is aimed at providing adjustability of the elasticity coefficient of the shock absorber and damping and the ability to fix two moving devices relative to the longitudinal axis of rotation, in particular the links of two-link tracked vehicles in any steady position at any time, as well as for damping the pumping units of pumping systems in the mining industry and damping vibrations in precision microelectromechanical systems.

[0006] The technical solution is achieved in that the diaphragm-piston shock absorber contains a hydraulic cylinder, a hydraulic cylinder base, a hydraulic cylinder piston, a piston rod, seals along the ends of the hydraulic cylinder, working fluid in the hydraulic cylinder, a hydraulic cylinder base, and elements of detachable mechanical connections on the outer ends of the piston rod for power control, while the hydraulic cylinder is made in the form of a sector of a cylindrical hollow ring with a sector angle of more than 90 °, the rod is made of two equal annular sectors with a sector angle of less than 90 ° and with a through hole along the length, the piston is made in the form of an annular sector of two detachable parts fastened to each other, with an internal cavity, with a non-circular through hole along the axis, with recesses along the outer ends for connection with the halves of the rod, and with radially extended through holes with a total width on a circle of any radius from the center the piston is less than half the circumference,and additionally comprises a screw-nut pair with a thread pitch greater than its diameter, with non-circular rods along the screw axis in both directions, two bearings mounted on the ends of the nut, a disk with a hole in the center and with radially extended holes with a total width on a circumference of any radius from the center of the disk less than half the length of the circumference, mounted axially symmetrically on the nut, wherein the screw-nut pair with the disk are placed in the internal cavity of the piston with rods in the central holes of the piston, and also additionally comprises two cables connected to the ends of the screw rods passed outward through the holes of the rod halves, cable seals on the outer ends of the piston rod halves, a fitting with a detachable sealed cover mounted on the hydraulic cylinder.

[0007] The operating principle of the diaphragm-piston shock absorber is based on the use of a ring-shaped hydraulic cylinder and a piston in the hydraulic cylinder, combined with an adjustable diaphragm, providing oscillations of the rod with the piston with an adjustable resistance force of the working fluid from free oscillations to complete fixation of the piston position in the hydraulic cylinder.

[0008] Fig. 1 shows the functional diagram of the diaphragm-piston shock absorber.

[0009] Fig. 2 shows the functional diagram of the piston of the diaphragm-piston shock absorber.

[0010] Fig. 3 shows a diagram of the relative position of the disk and piston forming the diaphragm in the open and closed state.

[0011] The numbering of positions in Fig. 1-3 is continuous.

[0012] The diaphragm-piston shock absorber (hereinafter referred to as the shock absorber) comprises (Fig. 1) a hydraulic cylinder 4, a piston 6, 8 of the hydraulic cylinder 4, a rod 1, 11 of the piston 6, 8, seals 3, 10 at the ends of the hydraulic cylinder 4, working fluid 5, 9 in the hydraulic cylinder 4, a base 18 of the hydraulic cylinder 4 and elements 20, 12 of detachable mechanical connections on the outer ends of the rod 1, 11 of the piston 6, 8 for power control. The parts of the detachable rod 1, 11 and piston 6, 8 are shown in the figures as separate positions. The hydraulic cylinder 4 is made in the form of a sector of a cylindrical hollow ring with a sector angle of more than 90°, the rod 1,11 is made of two equal annular sectors 1, 11 with a sector angle of less than 90° and with a through hole along the length, the piston 6, 8 is made in the form of an annular sector of two detachable parts 6, 8, fastened to each other with screws along axes O-O and O1-O1 (Fig. 2), with an internal cavity, with a non-circular through hole along the axis, with recesses along the outer ends for connection with the halves of the rod 1, 11 (Fig.1) and with radially extended through holes with a total width on a circle of any radius from the center of the piston 6, 8 (Fig. 2; Fig. 3) less than half the length of the circle. The piston 6, 8 (Fig. 2) in assembly, also being a diaphragm, contains a pair of "screw 27 - nut 24" with a thread pitch greater than its diameter, with non-circular rods 26, 29 along the axis of the screw 27 in both directions, two support bearings 28, 25 installed on the ends of the nut 24, a disk 7 (Fig. 1; Fig. 2; Fig. 3) with a hole in the center and with radially extended holes with a total width on a circle of any radius from the center of the disk 7 (Fig. 3) less than half the length of the circle, installed axially symmetrically on the nut 24 (Fig. 2), wherein the disk 7 (Fig. 1) and the pair of "screw 27 - nut 24" with support bearings 28, 25 in assembly are placed in the internal cavity of the piston 6, 8 non-circular rods 26, 29 (Fig. 2) in the central holes of the piston 6, 8. The shock absorber also contains two cables 2, 13 (Fig. 1, Fig. 2), connected to the ends of the rods 26, 29 (Fig.2) screw 27, respectively. Cables 2, 13 (Fig. 1) are passed outward through the axial holes of the rod halves 1, 12. The shock absorber contains seals 21, 14 for cables 2, 13 on the outer ends of the rod halves 1, 11 of the piston 6, 8, a nipple with a detachable sealed cover (not shown in Fig. 1) for introducing working fluid 5, 9, mounted on the hydraulic cylinder 4, elements 20, 12 of detachable mechanical connections on the outer ends of the rod 1, 11 of the piston 6, 8 for power control (elements for connecting the rod halves 1, 11 to the piston parts 6, 8 and the piston parts 6, 8 to each other are not shown in Fig. 1). The shock absorber assembly is mounted on the base 18 of the hydraulic cylinder 4. For the power control of the rod 1, 11 of the piston 6, 8, the shock absorber is equipped with radial rods 19, 15 with bent ends, inserted into the elements 20, 12 of the detachable mechanical connections at the ends of the halves of the piston 6, 8 of the rod 1, 11.

[0013] The pair "screw 27 - nut 24" is designed to rotate the disk 7 inside the piston 6, 8 (Fig. 2) with the help of cables 2, 13 (Fig. 1; Fig. 2). In one position of the disk 7 (Fig. 2), its radial holes coincide with the through radial holes of the piston 6, 8 (Fig. 2, the upper half of the disk 7; Fig. 3, the piston is open), and in the other position, the body of the disk 7 completely closes the holes of the piston 6, 8 (Fig. 2, the lower half of the disk 7; Fig. 3, the piston is closed). The piston 6, 8 with the disk 7 form an adjustable diaphragm. In Fig. 3 shows that with eight holes in the disk 7 and in the piston 6, 8, the angle of rotation between the above-mentioned positions is π / 8 (22.5°). For the disk to completely cover the piston holes, the sector angle of the holes in the disk 7 and piston 6, 8 must be less than 22.5°. Taking into account all the errors, the sector angle of the holes can be selected equal to 18°. To rotate the disk 7, it is necessary to turn the nut 24 by reciprocating the screw 27. This is accomplished with the help of cables 2, 13 (Fig.1; Fig. 2) under the following conditions. Screw 27 moves progressively, but does not rotate. For this purpose, rods 26, 29 of rectangular cross-section (non-circular) with a correspondingly shaped hole along the axis of the piston parts 6, 8 are made at the ends of the screw. The nut 24 does not move progressively along the axis of the piston 6, 8, but rotates freely around the axis of the screw 27 and the piston 6, 8. For this purpose, the nut 24 is mounted inside the piston 6, 8 on support bearings 28, 25. In this case, the screw 27 must be shorter than the nut 24 by more than the length of the progressive stroke of rotation of the disk 7 by the screw 27. For free rotation of the nut 24 and the disk 7 by the progressive movement of the screw 27, it is necessary that the thread pitch angle of the screw 27 - nut 24 relative to the direction of the force action of the screw 27 on the thread of the nut 24 be greater than 45° (relative to the axis of the thread). This condition is satisfied when the thread pitch is greater than its diameter.

[0014] The geometric dimensions of the proposed invention depend on the nature of the application. According to the principle of similarity, the shock absorber can be used both in micromachines and in powerful power devices, in particular in two-link tracked vehicles. For a conditional estimate, we will take the thread diameter of screw 27 to be equal to D = 10 mm, the thread pitch equal to two diameters h = 20 mm. Then the projection of the thread line onto the plane of the force direction, that is, onto the axial plane of screw 27, will be greater than 60°, which ensures sufficient sliding of the thread of screw 27 along the thread of nut 24. The magnitude of the translational movement of screw 27 to rotate disk 7 by an angle of 22.5° = 2 π / 16 is s = h / 16 = 2D / 16 = 20 / 16 = 1.25 mm. With such dimensions, smoothly changing the width of the open holes proves difficult. For smooth adjustment, it is necessary to select a thread pitch, for example, h = (10 - 50) D. Under this condition, the screw stroke will increase by 5-25 times.This step is well implemented by a multi-thread trapezoidal shape with a thread line projection angle of less than 15°, which ensures smooth regulation of the width of open holes by a moment of force acting distributedly on the thread of nut 24, equal to M = 2F. τ / D, where the tangential force acting on the thread of nut 24 is equal to F τ = F трос sinα cosα = 1 / 2F трос sin2α, where α = arctan(D / h). Then the tangential rotational force of nut 24 is equal to F τ = 1 / 2F трос sin(2arctg(D / h)), where F трос - cable tension force; D - thread diameter; h - thread pitch. Analysis of the resulting function shows that the ratio F τ / F трос- has a maximum at α = 45°, which is useful to take into account in micromachines with a low coefficient of friction of the working fluid. For a smooth change in the width of the piston-disk holes, small angles a are preferable. The smoothness of regulation can be improved by reducing the number of holes in the piston 6, 8 and disk 7. In this case, in the screw-nut design, the main characteristics are the diameter and pitch of the thread, as well as the length of movement of the screw 27 by cables 2, 13 for adjusting the width of the holes from the closed to the fully open position. Provided that the thread pitch h = 10 D, the length of movement of the screw 27 will be s = h / 16 = 100 / 16 = 6 mm. For smooth regulation of the width of the hole, it is possible to increase the thread pitch and decrease the number of holes in the piston 6, 8 and disk 7. A universal regulator of the smoothness of the motion transmission is an additional worm gear, which can be installed on the ends of the cables 2, 13.

[0015] The shock absorber assembly is carried out in the following sequence. Cables are connected to non-circular rods 26, 29 (Fig. 2) of screw 27. Disk 7 is secured on nut 24, nut 24 is screwed onto screw 27. Detachable parts of piston 6, 8 are installed with recesses 22, 23 on rod halves 1, 11 (Fig. 1). Parts of piston 6, 8 with rod halves 1, 11 are placed side by side. Cables 2, 13 are passed through the holes of rod halves 1, 11. The "screw 27 - nut 24" pair with disk 7 is installed inside piston 6, 8 with screw rods in the axial holes of the piston (Fig. 2). The piston assembly is connected and secured (tightened) loosely with screws along axes O-O and O1-O1. The piston assembly 6, 8 with rod 1, 11 is installed in hydraulic cylinder 4 and centered using process mandrels. The piston assembly with its rods is then extended toward the end of hydraulic cylinder 4, finally secured with screws (screw axes O-O and O1-O1 are shown in the figure), and moved toward the center of hydraulic cylinder 4.Then, seals 3,10 are installed on the ends of the hydraulic cylinder 4 and seals 21, 14 on the ends of the rod 1,11. Then, with all the technological procedures, the working fluid 5, 9 is poured into the hydraulic cylinder 4 of the shock absorber through the nipple (not shown in Fig. 1), and the shock absorber is sealed.

[0016] The shock absorber is designed to cushion an axisymmetric "housing-shaft" pair, specifically housing 16 and shaft 17 in the figure. For this purpose, base 18 of the hydraulic cylinder is secured to housing 16, and radial rods 19, 15 are connected to shaft 17, forming a symmetrical fork 19, 15 along the diameter of shaft 17 and creating a symmetrical torque at the ends of the fork, acting on elements 20, 12 of detachable mechanical connections at the outer ends of rod 1, 11 and, accordingly, on piston 6, 8 of the shock absorber. Note that the drive of the piston rod and the shock absorber as a whole is individual in each case of application.

[0017] The shock absorber operates in three modes: free oscillation, damping and fixing the angular position.

[0018] Free oscillation mode. Let's assume that piston 6, 8 of the shock absorber is located in the center of hydraulic cylinder 4, when the initial (horizontal) states, the working planes of the "housing-shaft" devices have no relative angular deviation. Let's assume that housing 16 is stationary and shaft 17 is angularly oscillating.

[0019] Let the disk 7 be installed on the nut 24 so that in the extreme left position of the screw 27 in the nut 24 inside the piston 6, 8, the holes of the disk 7 completely coincide with the holes of the piston 6, 8 (the diaphragm is open), and in the extreme right position of the screw 27, the disk 7 completely covers the holes of the piston (the diaphragm is open).

[0020] Set the shock absorber to free angular oscillation of the shaft within the housing. To do this, set the position of disc 7 so that piston holes 6 and 8 are fully open. By tightening cable 2, move screw 27 inside nut 24 to the extreme left position.

[0021] Let shaft 17 rotate clockwise (in the plane of the figure) relative to housing 16. Then, the fork of rods 19, 15 creates a symmetrical torque on elements 20, 12 of the detachable joints at the ends of halves of rod 1, 11 of piston 6, 8. In this case, rod 1, 11 and piston 6, 8 also rotate freely clockwise, and the working fluid flows freely through the open holes of piston 6, 8 with minimal resistance to pumping working fluid 5 from the left half of hydraulic cylinder 4 to the right half 9 through the piston holes. Therefore, shaft oscillations relative to the axis are ensured freely at an angle of ϕ / 2 = 45° in both directions. Angles greater than 45° are of an emergency nature.

[0022] Cushioning mode. By pulling right cable 13, we partially move screw 27 progressively to the right. This progressive movement is provided by rods 26 and 29 of rectangular (non-circular) cross-section in corresponding holes in piston sections 6 and 8. Screw 27 rotates nut 24 on support bearings 28 and 25 by an angle less than 22.5°. In this position of the disk 7, turning the shaft 17 and moving the piston 6, 8, for example, to the right, clockwise, leads to an increase in pressure in the right part 9 of the hydraulic cylinder 4 and to a decrease in pressure in the left part 5. Under the action of the pressure difference, the liquid 9 from the right part of the hydraulic cylinder 4 flows into the left part 5, experiencing local hydraulic resistance on the piston openings (diaphragms), narrowed by the disk 7. The coefficient of suppression of free oscillations of the shaft 17 increases with a decrease in the area of ​​the open part of the piston openings 6. 8. The more the right cable 13 is pulled, the more the piston openings 6, 8 are closed.The greater the resistance with which piston 6, 8 moves, the greater the resistance experienced by the shaft from the rods 19, 15 of the fork, connected to the elements 20, 12 of the detachable joints. The turning force of disk 7 is insignificant, since disk 7 moves across the fluid flow through the openings of disk 7 and piston 6, 8, and nut 24 rotates on support bearings 28, 25. As a result of friction of the layers of working fluid against each other in the piston area, the vibration energy is converted into heat, and fluid 5, 9 heats up. In powerful machines, it is advisable to equip the shock absorber hydraulic cylinder with a forced cooling system.

[0023] In the mode of fixing the position of shaft 17 relative to housing 16, cable 13 right is pulled to the limit, screw 27 moves to the right, nut 24 with disk 7 rotate until the holes of piston 6, 8 are completely closed. Due to the incompressibility of working fluid 5, 9, the position of piston 6, 8 in hydraulic cylinder 4 is fixed at the angle at which the piston holes were closed by disk 7. In this state, the turning moment of shaft 17 is completely transmitted to housing 16. In this mode, the highest pressure values ​​​​are created in the working fluid. Seals 3, 10 of hydraulic cylinder 4, and seals 21, 14 of cables 2, 13 must meet the requirements for the maximum pressure in hydraulic cylinder 4.

[0024] In a two-link tracked vehicle, the shock absorber, when locked in position, creates a rigid connection between the vehicle's links, doubling the weight of the link and weapon and improving the vehicle's stability during firing. By varying the azimuth angle between the links (in the horizontal plane), the proposed invention, by locking the links into a single rigid structure, creates a rigid support triangle within the link lengths, significantly reducing firing errors caused by vehicle hull vibrations.

[0025] A comparative analysis with the prototype showed that the proposed invention allows for free vibrations, damping of angular movements in the “housing-shaft” system with regulation of the damping force and ensures the fixation of two movable devices relative to the longitudinal axis, in particular two links of two-link tracked vehicles in any steady position at any time.

Claims

A diaphragm-piston shock absorber comprising a hydraulic cylinder, a hydraulic cylinder base, a hydraulic cylinder piston, a piston rod, seals along the ends of the hydraulic cylinder, working fluid in the hydraulic cylinder, a hydraulic cylinder base, and elements of detachable mechanical connections on the outer ends of the piston rod for power control, characterized in that the hydraulic cylinder is made in the form of a sector of a cylindrical hollow ring with a sector angle of more than 90°, the rod is made of two equal annular sectors with a sector angle of less than 90° and with a through hole along the length, the piston is made in the form of an annular sector of two detachable parts fastened to each other, with an internal cavity, with a non-circular through hole along the axis, with recesses along the outer ends for connection with the halves of the rod, and with radially extended through holes with a total width on a circumference of any radius from the center of the piston less than half the length of the circumference, and additionally contains a pair "screw-nut" with a thread pitch greater than its diameter,with non-circular rods along the screw axis in both directions, two bearings mounted on the ends of the nut, a disk with a hole in the center and with radially extended holes with a total width on the circumference of any radius from the center of the disk less than half the length of the circumference, mounted axially symmetrically on the nut, wherein the screw-nut pair with the disk are placed in the internal cavity of the piston with rods in the central holes of the piston, and also additionally contains two cables connected to the ends of the screw rods, passed outward through the holes of the rod halves, cable seals on the outer ends of the piston rod halves, a nipple with a detachable sealed cover mounted on the hydraulic cylinder.

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