Classifications

• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F16—ENGINEERING ELEMENTS AND UNITS; GENERAL MEASURES FOR PRODUCING AND MAINTAINING EFFECTIVE FUNCTIONING OF MACHINES OR INSTALLATIONS; THERMAL INSULATION IN GENERAL
  • F16F—SPRINGS; SHOCK-ABSORBERS; MEANS FOR DAMPING VIBRATION
  • F16F9/00—Springs, vibration-dampers, shock-absorbers, or similarly-constructed movement-dampers using a fluid or the equivalent as damping medium
  • F16F9/32—Details
  • F16F9/48—Arrangements for providing different damping effects at different parts of the stroke

Definitions

• the present invention relates to a hydraulic shock absorber.
• shock absorbers are widely used for arresting bodies in motion, for absorbing energy from impacts and generally controlling the motion of objects and equipment.
• a typical hydraulic shock absorber comprises a rod attached to a piston, w th the piston acting within a cylinder containing fluid. Forces acting upon the hydraulic shock absorber cause the piston to travel along the cylinder. Fluid within the cylinder is thus forced to pass from one side of the piston to the other side, during which process the energy of motion is converted to heat energy.
• a principal feature of shock absorbers is the manner in which fluid passes from one side of the piston to the other side. This may be through passageways in the cylinder walls or the piston.
• shock absorbers have only limited control features, or, if such features do exist, the resulting unit is bulky and expensive. There is, however, scope for incorporating various control features into a shock absorber that, for example, may be arranged to achieve near constant deceleration of a body acting on it whilst resulting in a compact and inexpensive unit.
• a hydraulic shock absorber comprising a cylinder; a piston rod; a fluid or fluids contained within the cylinder; a piston structure attached to the piston rod, the piston structure incorporating fluid conducting passageways; and means to regulate said fluid conducting passageways, said regulating means being controlled by relative displacement between said piston structure and the cylinder.
• Said piston structure may comprise a piston with such passageways,a slidably mounted tube and at least one spring which control(s) the position of said tube relative to the piston and thereby regulate(s) the capacity of said passageways to conduct fluid.
• the slidably mounted tube may be ported.
• the piston structure may incorporate a sleeve fixed relative to the piston and acting as a bearing surface between the tube and the piston, which sleeve may be ported.
• Means may be provided which compensates for variation in the internal volume of the shock absorber- due to relative movement between the piston rod and the cylinder.
• Means may be provided to permit adjustment of the rate of movement of the slidably mounted tube relative to the piston, thereby providing a means of adjusting the energy absorption rate to suit a variety of operating conditions.
• Means may be provided which, for a given position of the piston structure relative to the cylinder, allows the relative positions of the slidably mounted tube and the piston to be adjusted.
• the spring(s) which control(s) the position of the slidably mounted tube relative to the piston may be arranged so that it (they) act(s) tourge the piston structure towards one end of the cylinder.
• the outer surfaces of the shock absorber may be modified to facilitate the dissipation of heat to its surroundings.
• a non-return valve comprising an annular plate and a spring, the plate and the spring co-operating with the piston structure in such a way that some of the passageways in the piston structure are closed off while relative movement between the piston structure and the cylinder in one direction occurs and are opened while such movement in the opposite direction occurs.
• the non-return valve may be arranged so that such movement which results in withdrawal of the rod from the cylinder requires a lesser force than such movement which results in insertion of the rod into the cylinder.
• the piston structure and associated parts are arranged so that the relative movement between the piston structure and the cylinder which results in insertion of the rod into the cylinder requires a lesser force than such movement which results in withdrawal of the rod from the cylinder.
• a twin piston structure suitably arranged, which provides a shock absorber which, in effect, is double acting.
• a hydraulic shock absorber comprises a cylinder 1, a piston rod 2, screwed-in end caps 3 and 4, with end cap seals 5, and a rod seal 6.
• a hollow piston 7, open at one end, is attached to the piston rod 2 by means of a screw thread 8, which mates with a thread cut in the piston 7, and is secured by means of a lock nut 9.
• the piston 7 has in it a number of holes 10, drilled through the length of piston 7 parallel to the centre line axis of the cylinder 1 and disposed concentrically around the axis of piston 7.
• There are other holes 11 in piston 7 drilled radially and disposed of along a helical line around the piston. Each hole 11 intersects with a corresponding hole 10.
• a tube 12 slides within piston 7 and is held in position axially by springs 13 and 14.
• Spring 13 is located axially between piston 7 and tube 12.
• a plate 15 and spring 16 in co-operation with piston 7 and tube 12 act as a non-return valve.
• the plate 15 is able to move axially relative to the piston 7 whilst being spring-loaded towards the piston 7 by the action of spring 16.
• a closed cellular foam structure 17 is contained radially between cylinder 1 and a collar 18 and is held axially between end cap 3 and collar 18.
• piston 7 will move in the same direction, thereby compressing springs 13 and 14 and causing fluid to flow from one side of the piston to the other side along passageways, as indicated by arrow 19.
• the compression of the springs will cause tube 12 to move axially relative to piston 7 and some of the holes will be covered.
• further holes 11 will be covered, thus progressively restricting the flow of fluid through the passageways formed by holes 10 and 11. Whilst piston 7 is moving in direction 21, plate
• Plate 15 will, due to hydrodynamic force, be held away from the piston 7 in position 15a_, thus allowing flow of fluid from one side of piston 7 to the other side along passageways, as indicated by arrows 20. This is a less restricted flow path than that indicated by arrow 19, so the piston 7 and rod 2 will move relatively freely in the direction indicated by arrow 22.
• the springs 13 and 14 will extend as the piston 7 moves in the direction indicated by arrow 22, causing the tube 12 to move relative to piston 7 and to uncover holes 11. Closed cellular foam structure 17 will expand as the rod 2 moves out of the cylinder 1, thus preventing aeration of the fluid.
• a hydraulic shock absorber comprises a cylinder 1, a piston rod 2, screwed-in end caps 3 and 4, with end cap seals 5, and a rod seal 6.
• a hollow piston 7, open at one end is attached to the rod by means of a screw thread 8, which mates with a thread cut in the piston 7, and is secured by means of a lock nut 9.
• the piston 7 has in it a number of holes 10, drilled through the length of piston 7 parallel to the centre line axis of the cylinder 1 and disposed concentrically around the axis of piston 7. There is a groove 11 in the bore of piston 7 which intersects,, with holes 10.
• sleeve 24 within piston 7, the sleeve 24 being fixed in position relative to piston 7.
• the sleeve 24 may be a push fit in piston 7, but other means of fixing are possible.
• a tube 12 slides within sleeve 24 and is held in position axially by springs 13 and 14.
• Spring 13 is located axially between piston 7 and tube 12.
• Spring 14 is located axially between tube 12 and end cap 4, with a number of washers 23 (only one shown) held between spring 14 and end cap 4.
• a plate 15 and spring 16 in co-operation with piston 7 and tube 12 act as a non-return valve.
• the plate 15 is able to move axially relative to the piston 7 whilst being spring-loaded towards the piston 7 by the action of spring 16.
• a closed cellular foam structure 17 is contained radially between cylinder 1 and a collar 18 and is held axially between end cap 3 and collar 18. If a displacement is applied which causes movement of piston rod 2 in the direction indicated by arrow 21, piston 7 will move in the same direction, thereby compressing springs 13 and 14 and causing fluid to flow from one side of the piston to the other side along passageways, as indicated by arrow 19. The compression of the springs will cause tube 12 to move axially relative to sleeve 24 and part of the slot 25 will be covered. As the piston continues to move in the direction of arrow 21, slot 25 will be further- covered, thus progressively restricting the flow of fluid through the passageways formed by holes 10, groove 11 and slot 25.
• plate 15 Whilst piston 7 is moving in direction 21, plate 15 will be held against piston 7 by a hydrostatic force and spring 16, thus closing off the holes 10 on that side of the piston.
• the closed cellular foam structure 17 will be compressed as the rod occupies volume and displaces fluid within the cylinder.
• springs 13 and 14 When the driving force is removed, springs 13 and 14 will act to move the piston and the rod in the direction indicated by arrow 22. Plate 15 will, due to hydrodynamic force, be held away from the piston 7 in position 15a_, thus allowing flow of fluid from one side of piston 7 to the other side along passageways, as indicated by arrows 20. This is a less restricted flow path than that indicated by arrow 19, so the piston 7 and rod 2 will move relatively freely in the direction indicated by arrow 22.
• the springs 13 and 14 will extend as the piston 7 moves in the direction indicated by arrow 22, causing the tube 12 to move relative to sleeve 24 and uncover slot 25. Closed cellular foam structure 17 will expand as the rod 2 movesout of the cylinder 1, thus preventing aeration of the fluid.
• shock absorbers which cater for a range of operating conditions can be constructed from otherwise identical components.
• the initial position of tube 12 relative to sleeve 24 can be adjusted by inserting the required number of washers 23 between the spring 14 and end cap 4.
• a ' hydraulic shock absorber comprises a cylinder 1, a piston rod 2, an end cap 3 retained by a clip 27, a welded-in cap 4, an end cap seal 5, a rod seal 6 and a rod wiper ring 26.
• a hollow piston 7, open at one end, is attached to the rod by means of a screw thread 8, which mates with a thread cut in the piston 7, and is secured by means of a locking pin 9.
• the piston 7 has in it a number of holes 10, drilled through the length of piston 7 parallel to the centre line axis of the cylinder 1 and disposed concentrically around the axis of piston 7.
• There is an annular chamber 11 in piston 7 which communicates with holes 10 and 25.
• the tube 12 slides within piston 7 and is held in position axially by springs 13 and 14.
• Spring 13 is located axially between piston 7 and tube 12.
• Spring 14 is located axially between a spring carrier 24, which co-operates wi h tube 12, and end cap 4, wi h a number of washers 23 (only one shown) held between spring 14 and end cap 4.
• the plate 15 is able to move axially relative to the piston 7 whilst being spring-loaded towards the piston 7 by the action of spring 16.
• a closed cellular foam structure 17 is contained radially between cylinder 1 and a collar 18 and is held axially between end cap 3 and collar 18, the latter being a press fit in end cap 3 in contrast to Figures 1 and 2 where it is a screw fitting.
• piston 7 will move in the same direction, thereby compressing springs 13 and 14 and causing fluid to flow from one side of the piston to the other side along passageways, as indicated by arrow 19.
• the compression of the springs will cause tube 12 to move axially relative to piston 7 and some of the holes 25 will be covered.
• plate 15 will be held against piston 7 by a hydrostatic force and spring 16, thus closing off the chamber 11 on that face of the piston.
• the closed cellular foam 17 structure will be compressed as the rod occupies volume and displaces fluid within the cylinder.
• springs 13 and 14 When the driving force is removed, springs 13 and 14 will act to move the piston and the rod in the direction indicated by arrow 22. Plate 15 will, due to hydrodynamic force, be held away from the piston 7 in position 15a , hus allowing flow of fluid from one side of piston 7 to other side along passageways, as indicated by arrows 20. This is a less restricted flow path than that indicated by arrow 19, so the piston 7 and rod 2 will move relatively freely in the direction indicated by arrow 22.
• the springs 13 and 14 will extend as the piston 7 moves in the direction indicated by arrow 22,causing the tube 12 to move relative to piston 7 and uncover holes 25. Closed cellular foam structure 17 will expand as the rod 2 moves out of the cylinder l.thus preventing aeration of the fluid.
• the initial position of tube 12 relative to piston 7 can be adjusted by inserting the requried number of washers 23 between the spring 14 and end cap 4.
• a slot or slots according to Figure 2 may be used in the Figure 3 embodiment.

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• Engineering & Computer Science (AREA)
• General Engineering & Computer Science (AREA)
• Mechanical Engineering (AREA)
• Fluid-Damping Devices (AREA)

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• 1985
  • 1985-07-04 WO PCT/GB1985/000298 patent/WO1986000675A1/en unknown
  • 1985-07-04 GB GB08630908A patent/GB2185087B/en not_active Expired
  • 1985-07-04 EP EP19850903331 patent/EP0221064A1/de not_active Withdrawn

Non-Patent Citations (1)

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