Coupler

Abstract

A coupler pivot. A coupler (10) comprises at least a first gimbal (31; 32) defining a pivot that is secured to a mounting (41) for securing to a frame member of a vehicle, the pivot also being secured to a buffer column (39) part of which protrudes on an opposite side of the pivot to the mounting (41) such that the buffer column (39) is moveable relative to the mounting (41) with at least two degrees of freedom. The buffer column (39) defines a free (42) end that is remote from the mounting (41) and that is securable to a further member. The buffer column (39) also includes both a reversible buffer that attenuates buff and draft forces acting between the free end (42) and the mounting (41) and also a non-reversible buffer that attenuates buff forces acting between the free end (42) and the mounting (41) and attaining or exceeding a predetermined energy threshold, the reversible and non-reversible buffers overlapping over at least part of their lengths in the buffer column (39) which in turn overlaps at least one of the pivots.

Claims

1. A coupler comprising at least a first gimbal defining a pivot that is secured to a mounting for securing to a frame member of a vehicle, wherein the pivot additionally includes a second gimbal and wherein the axes of the gimbals are mutually orthogonal, the pivot also being secured to a buffer column that protrudes on an opposite side of the pivot to the mounting such that the buffer column is moveable relative to the mounting with at least two degrees of freedom, the buffer column defining a free end that is remote from the mounting and that is securable to a further member and the buffer column including both a reversible buffer that attenuates buff and draft forces acting between the free end and the mounting and also a non-reversible buffer that attenuates buff forces acting between the free end and the mounting and attaining or exceeding a predetermined energy threshold, the reversible and non-reversible buffers overlapping over at least part of their lengths in the buffer column that also overlaps at least one of the pivots.

2. A coupler according to claim 1 wherein the non-reversible buffer encircles the reversible buffer.

3. A coupler according to any preceding claim wherein the non-reversible buffer includes a plastically deformable, hollow tube defined by at least one tube wall having formed therein a tube taper that tapers in a direction towards the mounting; and an impact member defining a deforming taper of generally complementary shape to the tube taper, the deforming taper engaging the tube taper and the impact member being secured to the remainder of the buffer column such that on a high-energy buff force acting between the free end and the mounting that attains or exceeds the energy threshold the deforming taper plastically deforms the tube by causing the tube taper to travel towards the mounting and thereby attenuate the energy of the high-energy buff force.

4. A coupler according to claim 3 wherein the tube taper and the deforming taper are annular and encircle the reversible buffer.

5. A coupler according to claim 3 or claim 4 wherein the reversible buffer includes two or more relatively moveable buff attenuation members such that the reversible buffer is moveable between an intermediate and a compressed configuration; and wherein in the compressed configuration the reversible buffer is capable of contacting the impact member to cause plastic deformation of the hollow tube.

6. A coupler according to any of claims 3 to 5 wherein the mounting includes formed therein a recess or aperture; and wherein a part of the hollow tube protrudes via the recess or aperture.

7. A coupler according to claim 6 wherein the dimensions of the recess or aperture are such as to accommodate the tube taper with clearance on plastic deformation of the hollow tube.

8. A coupler according to any one of the claims 5, 6 and 7 wherein the buff attenuation members include a compressible fluid spring having a piston lying within a buffer tube that is sealingly moveable on the interior of the piston so as to define a chamber that contains a compressible fluid, the arrangement being such that on movement of the reversible buffer from the intermediate to the compressed configuration the compressible fluid becomes compressed in the chamber.

9. A coupler according to any one of the claims 5-8 wherein the buff attenuation members include a reversible buffer having buffer capsule or assembly in which a piston is sealingly slideably received inside the hollow interior of an elongate tube and on compression forces a fluid such as an oil through a series of valves and orifices in order to dissipate energy tending to compress the buffer.

10. A coupler according to any preceding claim wherein the non-reversible buffer includes or is operatively connected to a tell-tale that provides a visible indication of whether the non-reversible buffer has been activated.

11. A coupler according to any preceding claim wherein the reversible buffer includes two or more relatively moveable draft attenuation members such that the reversible buffer is moveable between an intermediate and an extended configuration, the reversible buffer including between the draft attenuation members one or more resiliently deformable members that attenuate draft forces.

12. A coupler according to any preceding claim the free end of which includes one or more coupler formations for securing the coupler pivot to a said further member.

13. A vehicle including secured thereto the mounting of a coupler pivot according to any preceding claim.

14. A vehicle according to claim 13 or claim 6 including formed therein a recess for accommodating with clearance the part of the hollow tube that protrudes via the recess or aperture of the mounting.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) There now follows a description of preferred embodiments of the invention, with reference being made to the accompanying drawings in which:

(2) FIG. 1 is a cross-sectional view of a prior art EFG coupler pivot, shown in the condition resisting a draft force tending to pull a coupler element out of the interior of a gimbal;

(3) FIG. 2 shows the FIG. 1 EFG when absorbing the energy of a draft force and a vertical relative movement between coupled vehicles;

(4) FIG. 3 is a perspective view of a coupler pivot according to the invention;

(5) FIG. 4 is a vertically cross-sectioned view of the FIG. 3 coupler pivot; and

(6) FIG. 5 is a horizontally cross-sectioned view of the free end of the coupler pivot of FIGS. 3 and 4.

DETAILED DESCRIPTION

(7) Referring to FIGS. 3 to 5 a coupler 30 comprises a pair of gimbals 31, 32 that define a corresponding pair of pivots the pivot axes of which intersect at ninety degrees to one another. The coupler is intended for coupling together in the manner described in general herein an adjacent pair of vehicles that normally would be rail-mounted.

(8) The pivot axis defined by gimbal 31 is in the embodiment shown vertical and that of gimbal 32 horizontal in normal use of the coupler pivot 30. However in other embodiments of the invention it need not necessarily be the case that the axes of the gimbals are so orientated, or indeed intersect orthogonally as stated.

(9) Furthermore in simple versions of the invention only a single gimbal needs to be provided, that accommodates relative movements between adjacent vehicles in a horizontal plane and therefore provides for a single degree of freedom coupler pivot. In most practical embodiments of the invention however the two degree of freedom version, having mutually orthogonally acting gimbals as shown, is preferred.

(10) Each gimbal 31, 32 comprises a respective cuboidal frame 33, 34 that preferably is e.g. a steel casting or is fabricated. The cuboidal frame of horizontal axis gimbal 32 is smaller than that of vertical axis gimbal 31 whereby as illustrated frame 34 fits inside frame 33.

(11) On each of two parallel walls 33a, 33b frame 33 supports a respective journal bearing 36a, 36b of which only one, 36a, is visible in FIG. 3.

(12) Each journal bearing 36a, 36b includes a cylindrical member 37 secured to and extending through it such that the cylindrical member is rotatably supported relative to the frame 33.

(13) Each cylindrical member 37 is secured to the exterior of cuboidal frame 34 with the result that the latter is rotatably supported relative to frame 33, such that the axis of rotation is vertical.

(14) Similar journal bearing 38 arrangements are provided in cuboidal frame 34, including cylindrical members that extend horizontally to connect to a curved bracket 46 that extends forwardly to secure rigidly to a buffer column 39 part of the length of which is received inside cuboidal frame 34. In the embodiment shown the curved bracket 46 is perforated by the buffer column that is of circular cross-section. The buffer column 39 therefore may be made as a tight (e.g. press) fit inside the perforation in the curved bracket 46, which as shown in FIG. 3 extends to attach to the cylindrical members on each side of gimbal 32.

(15) As a result buffer column 39 is pivotably mounted relative to frame 34 by way of a horizontal pivot axis. This together with the pivoting mounting of the frame 34 relative to frame 33 means that the buffer column 39 is pivotably secured relative to cuboidal frame 34 with two degrees of freedom, and with the axes of pivoting intersecting orthogonally as described.

(16) The frames 33, 34, journal bearings 36, 38 and related parts amount to a pair of gimbals defining a pivot.

(17) Cuboidal frame 33 is secured to a mounting in the form of a bracket plate 41. This is a rigid, typically metal, plate that is perforated for rigid securing to the aforementioned beam forming part of the frame of a vehicle. It follows that the buffer column 39 is pivotably supported with two degrees of freedom relative to the mounting constituted by bracket plate 41, and hence with two degrees of freedom relative to any vehicle to which the coupler is in use secured.

(18) At its end remote from bracket plate 41 buffer column 39 defines an end 42 that is referred to herein as the free end of the buffer column (this end being free when the column is not connected to any further component).

(19) In the illustrated embodiment, the free end 42 includes a groove 43 that allows its securing, for example by way of a per se known muff connector, to a further component such as an element of the coupler of an adjacent vehicle. Groove 43 therefore preferably is constituted as a muff groove the design of which would be familiar to the person of skill in the art. Other connector arrangements, as would be known to the person skilled in the art, however may be provided at free end 42.

(20) As described in more detail below the buffer column 39 includes inside its interior both a reversible buffer that attenuates buff and draft forces acting between the free end and the mounting and also a non-reversible buffer that attenuates buff forces acting between the free end and the mounting and attaining or exceeding a predetermined energy threshold.

(21) The reversible buffer and the non-reversible buffer overlap over part of the length of the buffer column 39 which in turn overlaps one or more of the pivots 31, 32. The means by which this is achieved are explained below. As noted a significant advantage of this aspect of the embodiment is that it permits a multi-function buffer to be accommodated without excessively increasing the length of the coupler as in prior art arrangements.

(22) As best illustrated in FIG. 4, the non-reversible buffer is constituted by a plastically deformable (typically but not necessarily steel) elongate, hollow essentially cylindrical tube 44 that lies principally within cuboidal frame 34.

(23) Hollow tube 44 is of constant diameter over most of its length and encircles further parts of the buffer column 39, described below, lying within cuboidal frame 34. A portion of the hollow tube 44 however protrudes outwardly form the cuboidal frame 34 on the same side of the frame as the free end 42 of the buffer column.

(24) In the vicinity of this part the hollow tube 44 enlarges in diameter to define an annular taper 47 in the material of its cylindrical wall 48. As shown in FIG. 4 this taper 47 tapers in a direction towards the bracket plate 41.

(25) An impact member in the form of an annular wedge 49 tapering in the same direction and with approximately the same shape as the inside of taper 47 is received in the hollow interior of tube 44. Wedge 49 extends towards bracket plate 41 to define a plunger 51 terminating in a closed end 52. Closed end 52 acts as a reaction surface for reversible buffer parts described below.

(26) The reversible buffer parts are constituted by a cylindrical piston member 53 that at one end 53a is sealingly secured to the interior of closed end 52 of hollow tube 44 and at the opposite end terminates in a piston end member 54.

(27) A separator 54a is sealingly slideably provided on the inner surface of piston member 53 such that a fluid chamber 57a is defined between the piston member 53, separator member 54a and closed end 53a. A compressible gas is captured in the fluid chamber 57a such that the piston member 53, separator member 54a and closed-ended tube 53a define a resiliently deformable gas spring that on compression longitudinally resiles by reason of the energy thus imparted to the compressible fluid in chamber 57a.

(28) Sealingly slideably received on the external surface of piston member 53 is a closed-ended, hollow tube 56 that is open at an end opposite its closed end and that partially overlaps along the length of the piston member 53.

(29) Closed-ended tube 56 is closed at its end remote from piston member 53 with the result that a fluid chamber 57 is defined between the piston end 54 and the interior walls of closed-ended tube 56.

(30) A fluid such as oil is captured in the fluid chamber 57 such that on compression of the buffer the fluid becomes forced through a series of valves and orifices (not shown) in piston end 54.

(31) Fluid flowing through the orifice and valves in piston end 54 at such a time enters the space between piston end 54 and the separator 54a. To accommodate the oil the separator 54a moves in the direction of closed end 53a resulting in a reduction of the volume of chamber 57a and compression of the gas in chamber 57a.

(32) The gas spring tends to cause the coupler pivot to adopt the configuration shown in FIGS. 3 and 4, which position is referred to herein as an intermediate position.

(33) The axis of the resulting reversible energy absorber coincides with the operative axis of a non-reversible buffer defined by the taper 47 and impact member (annular wedge) 49.

(34) As is apparent from the lengths of the piston member 53 and closed-ended tube 56 the reversible buffer overlaps over a significant part of its length with the non-reversible buffer, thereby leading to a compact arrangement. The non-reversible buffer moreover encircles the reversible one.

(35) Closed-ended tube 56 lies within a hollow, cylindrical shroud 58 that extends parallel to the buffer column and terminates at its end nearest bracket plate 41 in a flange 59 that engages the end of hollow tube 44. A clamp ring 61 encircles the flange 59 and binds the shroud and the hollow tube together.

(36) By reason of their respective diameters an annular space 62 exists between the exterior of closed-ended tube 56 and the interior of shroud 58. A circular cross-section column member 63 is hollow over the major part of its length and encircles the closed-ended tube in the annular space 62. Column member 63 is slideable in the space 62.

(37) Part-way along the length of its interior column member 63 is divided in two by a mounting disc 64. The remainder of the length of column member 63 is again hollow until it terminates at an open end 66.

(38) Open end is plugged by a draft attenuator cup 67 that is inserted into the interior of column member 63 on the opposite side of the mounting disc 64 to that of the reversible buffer and the taper 47 and related components. The muff groove 43 is formed in an external part of this component that as shown protrudes outwardly from the open end of the column member 63.

(39) A spring retainer rod 68 extends inside draft attenuator cup 67 and is secured at one end to it. At its opposite end retainer rod 68 pierces a transverse member 69 that extends through transversely formed perforations 71 in the wall of column member 63 to either side of the retainer rod 68.

(40) Trapped between the transverse member 69 and the mounting disc 64, and perforated by the retainer rod 68 is a stack of essentially abutting annular spring elements 76 that are elastomeric and are spaced from one another by washers 72 the functions of which are known in the spring art.

(41) The reversible buffer operates when forces exerted between the ends of the coupler pivot are relatively small. Buff forces cause compression of the coupler pivot between its ends with the result that forces experienced at the muff ring 43 are transmitted via the draft attenuator cup to the mounting disc 64 and thence to the closed end of closed ended tube 56.

(42) This causes the closed-ended tube 56 to move in the general direction of the bracket plate, with the wall of the closed ended tube 56 sliding in a further annular space 23 existing between the interior of the plunger 51 and the exterior of the piston member 53.

(43) During this process the oil in chamber 57 flows through the orifices and valves in piston end 54 and the gas in the chamber 57a becomes compressed and thereby energised. When the buff force is released the resulting stored energy causes expansion of the gas and thereby drives the closed-ended tube back to the intermediate position shown in FIGS. 3 and 4.

(44) If a relatively low energy draft force is experienced this induces tension in the coupler pivot 10. This tends to draw the column member 63 off the end of the closed-ended tube 56, but this tendency is resisted because the column member 63 is retained inside the shroud 58 by an annular collar 74 that is retained in the open end of the shroud 58. The collar 74 is engaged on outward stroking of the column member 63 by an annular ridge 81 formed on the external surface of column member 63.

(45) A key 78 engages with a groove in the annular ridge 81 of column member 63 which together with the transversely formed perforations 71 engaging in the wall of column member 63 and attenuator cup 67 prevent the muff ring 43 rotating around the axis of the buffer element relative to the mounting 41.

(46) Following such engagement between the collar 74 and the ridge 81 any further tensile force acts via the muff ring 43 and attenuator cup 67 and is transferred to the transverse member 69 and thence to the column member 63. This causes compression of the spring elements between the end of attenuator cup 67 and the transverse member 69. Since the spring elements are resiliently deformable this action attenuates the energy of the draft event until the stroke is exhausted by the extent of the transversely formed perforations 71 in the wall of column member 63.

(47) Once the event has terminated the stored energy in the spring elements causes them to expand, in turn causing the cup to be returned to the position shown in FIG. 4.

(48) In the event of a significant impact, as may arise in an accident situation, high-frequency compression energy is imparted to the coupler pivot with the result that the reversible buffer becomes fully stroked. As a consequence the open end of column member 63 nearest to bracket plate 41 engages the rear face of annular wedge 49 and drives its taper further into engagement with the taper 47 in the wall of the hollow tube 44.

(49) Assuming the impact is sufficiently energetic this causes the taper 47 to travel along the wall towards the bracket plate 41, permanently deforming the hollow tube 44 in an energy attenuating manner. The high impact force experienced in an accident therefore is safely and predictably absorbed.

(50) The dimensions of the cuboidal frame 34 are such that even following such deformation of the hollow tube 44 (which results in the enlarged diameter part of it moving closer to the bracket plate 41) there remains sufficient clearance between the hollow tube and the cuboidal frame 34 as to allow the gimbals 31, 32 to continue to function. Thus the risk of a derailment that would be caused by locking up of the coupler pivot in an accident is likely to be avoided.

(51) As is signified schematically the embodiment visible in FIG. 4 part of the length of the hollow tube protrudes through an aperture in the bracket plate 41. This also allows for overall compactness of the coupler, with the pivot axes overlapping the coupler element. This reduces the turning moments that might arise in a very long device (such as those of the prior art) in which a compressive force acts off-centre. Therefore the chances of the reversible buffer part of the coupler pivot locking up in use are reduced.

(52) As is apparent from FIG. 3 a tell-tale 77 is provided on the column member 63. This is a visual indicator of whether the non-reversible buffer has been stroked. The tell-tale 77 may take a range of forms that are known to the person of skill in the art.

(53) Following use of the buffer 30 it is therefore immediately apparent whether the hollow tube has been plastically deformed as described above. The safety of the coupler therefore can be readily assessed.

(54) Yet a further benefit of the arrangement of the invention is that the presence of the deformable hollow tube in partial overlap with the parts of the reversible buffer described above means that the latter are likely to be protected against damage in the event of a high-energy impact occurring. Thus following even a severe impact it is likely that only the hollow tube 44 would require replacing before the coupler pivot became useable again.

(55) Various details of the coupler pivot may be changed within the scope of the invention. In particular the relative dimensions of the parts illustrated may be varied, for example to provide couplers of varying sizes and operational duties. Also the type of reversible buffer may be altered, it being necessary only that this part of the coupler fits inside the space available between the plunger 51 and the column member 63.

(56) Yet a further variation within the scope of the invention relates to the number and size of the spring elements 76.

(57) Overall as indicated the invention represents a considerable improvement, at reasonable cost, over the coupler of the prior art.

(58) The listing or discussion of an apparently prior-published document in this specification should not necessarily be taken as an acknowledgement that the document is part of the state of the art or is common general knowledge.