Filling method a gas spring and machine implementing such method

Abstract

Filling method a gas spring (1) comprising: an outer casing (2) made up of a cup-shaped body (5), a plug body (6) that is at least partially fitted into the cup-shaped body (5) in so as to delimit a closed cavity (3), and at least one annular sealing gasket (7) interposed between the plug body (6) and the cup-shaped body (5) to prevent the leakage / passage of the pressurized gas between the two elements; a rod-piston (4), which is fitted into the outer casing (2) in axially-slidable manner, and is structured so as to form / delimit, together with the inner cavity (3) of the casing, a variable volume closed chamber capable of containing a pressurized gas; the filling method comprising the steps of: arranging the annular sealing gasket (7) of the outer casing (2) inside the cup-shaped body (5) in a non-sealing position wherein the annular sealing gasket (7) allows the passage of gas from and to said closed cavity (3); introducing the pressurized gas into the closed cavity (3) by passing it through the interstitial space between said cup-shaped body (5) and said plug body (6); and finally arranging / moving the annular sealing gasket (7) in a sealing position wherein the annular sealing gasket (7) of the outer casing (2) fluid tight isolates / seals said closed cavity (3).

Description

[0001] "FILLING METHOD A GAS SPRING AND MACHINE IMPLEMENTING SUCH METHOD"

[0002] Cross-Reference to Related Applications

[0003] This Patent Appl ication claims priority from Italian Patent Application No . 102023000005445 filed on March 22 , 2023 , the entire disclosure of which is incorporated herein by reference .

[0004] Technical Field

[0005] The present invention relates to a filling method of a gas spring and to a machine implementing that method .

[0006] More speci fically, the present invention relates to a filling method a gas spring suitable for use in the sheet metal forming filed . Use to which the following di sclosure will make explicit reference without losing in generality .

[0007] Background Art

[0008] As is known, the gas springs that are used in moulds for sheet metal forming generally comprise : a cup-shaped body substantially cylindrical in shape ; a guide bushing, separate and distinct from the cup-shaped body, which fluid- tight closes the mouth of the cup-shaped body by the interposition of a series of annular sealing gaskets ; and a piston-rod substantially cylindrical in shape , which is fitted in pass-through and axially slidable manner in the hole at centre of the guide bushing, so as to move axially with respect to the cup-shaped body between a retracted position and an extracted or extended position .

[0009] More speci fical ly, the piston-rod is fluid-tight inserted in the guide bushing via the interposition of a series of annular sealing gaskets , so as to for / delimit , together with the cup-shaped body and the guide bushing, a variable-volume closed chamber that is filled with a high- pressure gas .

[0010] The high-pressure gas keeps the piston-rod in the extracted or extended position, i . e . with the inner flanged end of the piston-rod in abutment against the guide bushing, until the piston-rod undergoes an axial force that can overcome the gas thrust .

[0011] Generally, the bottom of cup-shaped body is moreover provided with two straight ducts , which connect the variablevolume closed chamber with the outside and are fluid-tight closed, respectively, by a one-way valve ( also called nonreturn valve ) and a safety plug .

[0012] The one-way valve is oriented so as to allow the pressuri zed gas to enter into the variable-volume closed chamber, and is passed through by the pressuri zed gas during the filling of the gas spring .

[0013] The safety plug, on the other hand, is structured so as to automatically discharges the pressuri zed gas outside the gas spring when the piston-rod makes an "over-travel" , i . e . when the piston-rod retracts into the cup-shaped body exceeding the maximum stroke allowed by the gas spring ' s dimensions .

[0014] Unfortunately, the one-way valve has relatively high production costs . In addition, the reali zation of the housing seat of the one-way valve and the assembly of the same one-way valve have relatively high costs that signi ficantly contribute to the overall production costs of the gas spring .

[0015] Summary of the Invention

[0016] Aim of the present invention is to reduce the gas-springs production costs .

[0017] In accordance with these aims , according to the present invention there i s provided a filling method of a gas spring as defined in claim 1 and preferably, though not necessarily, in any one of the claims depending thereon .

[0018] According to the present invention, there is moreover provided a gas spring filling machine as defined in claim 10 and preferably, though not necessarily, in any one of the claims depending thereon .

[0019] According to the present invention, it is finally reali zed a gas spring as defined in claim 18 .

[0020] Brief Description of the Drawings

[0021] The present invention will now be described with reference to the accompanying drawings , which show a nonlimiting embodiment thereof , wherein :

[0022] - Figure 1 is a perspective view o f a gas spring reali zed according to the dictates of the present invention, with parts removed for clarity' s sake ;

[0023] - Figure 2 is a side view of the gas spring shown in Figure 1 , sectioned along the midplane and with parts removed for clarity' s sake ;

[0024] - Figure 3 is a perspective view of the gas spring shown in Figures 1 and 2 suitably coupled to a corresponding filling machine made according to the dictates of the present invention;

[0025] - Figure 4 is a partially-exploded side view of the filling machine shown in Figure 3 , with parts in section and parts removed for clarity' s sake ;

[0026] - Figures 5 to 10 schematically show some steps of the filling of the gas spring shown in Figures 1 and 2 ; whereas

[0027] - Figure 11 is a side view, with parts in section and parts removed for clarity' s sake , of a variation embodiment of the gas spring shown in Figures 1 and 2 and of the related filling machine .

[0028] Detailed Description of the Embodiments

[0029] With reference to Figures 1 and 2 , number 1 denotes , as a whole , a gas spring that can be advantageously used in presses or moulds for cold forming of metal sheets and the like .

[0030] The gas spring 1 comprises : an outer casing 2 with a rigid and sel f-supporting structure , which is internally provided with a large , advantageously complementary shaped, closed cavity 3 which is insulated from the outside ; and an oblong-shaped piston-rod 4 , which is fitted in the outer casing 2 in axially slidable and fluid-tight manner , normally protrudes cantilevered outside the casing 2 , and is shaped / structured so as to form / delimit , together with the cavity

[0031] 3 of casing 2 , a variable-volume closed chamber that contains or is adapted to contain nitrogen or other pressuri zed gas .

[0032] More in detail , the piston-rod 4 is inserted in axially slidable and fluid-tight manner into a substantially complementary shaped, rectilinear hole which is reali zed in the outer casing 2 in such a way to connect the cavity 3 directly with the outside . Preferably, the piston-rod 4 is moreover shaped / structured so as to also protrude cantilevered into the closed cavity 3 .

[0033] In addition, the part of piston-rod 4 that remains permanently inside the casing 2 , or rather protrudes cantilevered into the closed cavity 3 , is preferably provided with an anti-extraction structure adapted to prevent the piston-rod 4 from completely coming out from the casing 2 due to the thrust exerted by the pressuri zed gas .

[0034] The pressuri zed gas present inside the closed cavity 3 , or rather inside the variable-volume closed chamber, in turn has a higher pressure than the external one so as to maximise the volume of the closed chamber .

[0035] In other words , the pressuri zed gas present within the closed cavity 3 , or rather within the variable-volume closed chamber, is capable of bringing and maintaining the piston- rod 4 in an extended or extracted position ( see Figures 1 and 2 ) , wherein the anti-extraction structure of piston-rod

[0036] 4 is arranged in abutment against the inner surface of cavity 3 .

[0037] In the example shown, in particular, the nominal pressure of the gas contained in cavity 3 ( i . e . the gas pressure with the piston-rod 4 in the extracted or extended position) , or rather in the variable-volume closed chamber, preferably ranges between 20 and 350 bar . With reference to Figures 1 and 2 , in particular, the outer casing 2 is preferably substantially cylindrical in shape and is preferably made of metal material . The closed cavity 3 , similarly, is preferably substantially cylindrical in shape and preferably extends within the casing 2 substantially coaxial to the longitudinal / central axis A of the same casing 2 .

[0038] The piston-rod 4 , in turn, is preferably substantially cylindrical in shape , is preferably made of metal material , and preferably extends substantially coaxial to the longitudinal / central axis A of casing 2 .

[0039] More in detail , the outer casing 2 comprises : a cupshaped body 5 advantageously substantially cylindrical in shape , which preferably has a monolithic structure and is preferably also made of metal material ; a plug body 6 , separate and distinct from the cup-shaped body 5 , which has a shape substantially complementary to that of the mouth of the cup-shaped body 5 , and is at least partially fitted into the mouth of cup-shaped body 5 so as to delimit the closed cavity 3 ; and at least one annular sealing gasket 7 advantageously made of polymeric material , which is interposed between the plug body 6 and the cup-shaped body 5 , and is adapted to prevent the pressurised-gas leakage between the cup-shaped body 5 and the plug body 6 .

[0040] Even more speci fically, the cup-shaped body 5 is preferably provided with a one and only access opening to the inner cavity, and the plug body 6 is adapted to substantially fluid-tight close said access opening together with the annular sealing gasket 7 .

[0041] In addition, similarly to cup-shaped body 5 , also the plug body 6 preferably has a monolithic structure and is preferably made of metal material .

[0042] Preferably, the outer casing 2 is moreover provided with a locking member 8 , which is advantageously located at the mouth of cup-shaped body 5 , and is adapted to stably lock / hold the plug body 6 within the cup-shaped body 5 .

[0043] With reference to Figures 1 and 2 , in turn, the piston- rod 4 is preferably fitted in pass-through and axially slidable manner into the plug body 6 . In addition, the piston-rod 4 is preferably also substantially fluid-tight fitted into the plug body 6 .

[0044] In other words , the plug body 6 is preferably provided with a straight through hole advantageously circular in shape , which preferably has a cross-section substantially complementary to that of piston-rod 4 , and is engaged in pass-through and axially slidable manner by the piston-rod 4 .

[0045] Preferably, the piston-rod 4 is moreover fluid-tight coupled to the plug body 6 by means of an annular seal ing gasket 9 advantageously made of polymeric material , which is interposed between the piston-rod 4 and the plug body 6 and is adapted to prevent the leakage / passage of pressuri zed gas into the interstitial space between the piston-rod 4 and the plug body 6 .

[0046] More in detail , with reference to Figures 1 and 2 , in the example shown the plug body 6 preferably consists of a guide bushing advantageously substantially cylindrical in shape , which preferably has a monolithic structure and is preferably made of metal material . Said guide bushing, moreover, has a shape substantially complementary to the mouth of cup-shaped body 5 , and is provided with a central through-hole substantially circular in shape , which has a diameter substantially complementary to that of piston-rod 4 .

[0047] The annular sealing gasket 7 moreover is preferably accommodated within an annular groove made on the outer surface of the guide bushing .

[0048] The annular seal 9 , on the other hand, is preferentially accommodated within an annular groove made in the central through-hole of the guide bushing . The locking member 8 , on the other hand, preferably includes a Seeger spring ring or the like , advantageously made of metal material , which is preferably adapted to engage , in a removable manner , a corresponding annular groove reali zed in the cavity of cup-shaped body 5 , close to the mouth of the latter .

[0049] With reference to Figures 1 and 2 , the piston-rod 4 , in turn, preferably has a monolithic structure and is preferably made of metal material .

[0050] More in detail , the piston-rod 4 preferably consists of a substantially cylindrical-shaped cup-shaped body, which is fitted in axially slidable manner into the plug body 6 , or rather into the guide bushing, with the concavity turned towards the inside of cup-shaped body 5 , and advantageously also has , at the mouth, a protruding annular flange that is adapted to prevent the cup-shaped body from being completely extracted from the plug body 6 , or rather from the guide bushing .

[0051] With reference to Figures 2 and 4 , in addition, the annular sealing gasket 7 is axially movable inside the substantially rectilinear cavity of cup-shaped body 5 between a sealing position ( see Figure 2 ) wherein the annular sealing gasket 7 prevents the leakage / passage of pressuri zed gas into the interstitial space between the cup-shaped body 5 and the plug body 6 , and a non-sealing position ( see figure 4 ) wherein the annular sealing gasket 7 allows the gas to pass / pass through the interstitial space between the cupshaped body 5 and the plug body 6 .

[0052] In other words , when in the non-sealing position, the annular sealing gasket 7 allows the passage of the gas to and from the closed cavity 3 .

[0053] Preferably, the distance d of the annular sealing gasket 7 from the bottom of cup-shaped body 5 moreover assumes the maximum value when the annular sealing gasket 7 is in the sealing position, and assumes the minimum value when the annular sealing gasket 7 is in the non-sealing position .

[0054] More in detail , the cup-shaped body 5 is preferably provided, on the lateral surface of its inner cavity, with a small bypass notch or indentation 10 which is suitably spaced from both the bottom and the mouth of cup-shaped body 5 .

[0055] When the annular sealing gasket 7 is aligned with the indentation 10 ( see figure 4 ) , the gas can bypass the annular sealing gasket 7 and freely flow to and from the closed cavity 3 of casing 2 . When, instead, the annular sealing gasket 7 is staggered / misaligned with respect to the indentation 10 ( see figure 2 ) , the body of annular sealing gasket 7 prevents any gas passage / leakage in the interstitial space between the cup-shaped body 5 and the plug body 6 .

[0056] Preferably, the annular sealing gasket 7 is therefore axially movable within the cavity of cup-shaped body 5 between a sealing position ( see figure 2 ) wherein the annular sealing gasket 7 is staggered / misaligned with respect to the indentation 10 , and a non-sealing position ( see figure 4 ) wherein the annular sealing gasket 7 is aligned with the indentation 10 .

[0057] With reference to Figures 2 and 4 , in the example shown, in particular, the annular sealing gasket 7 is preferably f itted / mounted on the outer periphery of plug body 6 , or rather of the guide bushing, so as to moves axially substantially only together with the plug body 6 .

[0058] More in detail , the annular groove of plug body 6 , or rather of the guide bushing, accommodating the annular sealing gasket 7 preferably has a height that approximates by excess the height h of the same gasket , so as to prevent any axial displacement of the annular sealing gasket 7 with respect to the plug body 6 .

[0059] The plug body 6 , in addition, is preferably capable of moving axially within the cup-shaped body 5 between a final operating position and a temporary position . In the final operating position, the plug body 6 arranges the annular sealing gasket 7 in the sealing position, or rather keeps / retains the annular sealing gasket 7 staggered / misaligned with respect to the indentation 10 , so as to fluid-tight seal the closed cavity 3 . In the temporary position, on the other hand, the plug body 6 arranges the annular sealing gasket 7 in the non-sealing position, or rather aligns the annular sealing gasket 7 to the indentation 10 , so as to allow the passage o f gas in the interstitial space between the cup-shaped body 5 and the plug body 6 .

[0060] In other words , when the plug body 6 , or rather the guide bushing, is in the temporary position, the annular sealing gasket 7 allows the gas to flow to and from the closed cavity 3 .

[0061] Preferably, the distance of plug body 6 from the bottom of cup-shaped body 5 moreover assumes the maximum value when the plug body 6 , or rather the guide bushing, is in the final operating position and assumes the minimum value when the plug body 6 , or rather the guide bushing, is in the temporary position .

[0062] In addition, in the final operating position, the plug body 6 , or rather the guide bushing, is preferably located substantially at the mouth of cup-shaped body 5, and arranges the annular sealing gasket 7 between the indentation 10 and the mouth of cup-shaped body 5 .

[0063] More in detail , with reference to Figures 2 and 4 , in the final operating position, the plug body 6, or rather the guide bushing, preferably protrudes outside the cup-shaped body 5 by a few millimetres .

[0064] In the temporary position, instead, the plug body 6 , or rather the guide bushing, is preferably substantially entirely retracted within the cup-shaped body 5 , and arranges the annular sealing gasket 7 at the indentation 10 .

[0065] The filling method of gas spring 1 with the pressuri zed gas basically entails the steps of : arranging the annular sealing gasket 7 in the non-sealing position, so as to allow the gas to freely flow from and to the closed cavity 3 of casing 2 ; introducing the pressuri zed gas into the closed cavity 3 causing it to pass through the interstitial space between the cup- shaped body 5 and the plug body 6 ; and finally arranging / moving the annular sealing gasket 7 in the sealing position, so as to fluid-tight isolate / seal the closed cavity 3 of casing 2 .

[0066] More in detail , the filling method of gas spring 1 with the pressuri zed gas comprises the steps of : creating / forming, at the mouth of cup-shaped body 5 , a closed space / volume which is preferably capable of containing part of the plug body 6 , or rather of the guide bushing, and / or of the piston-rod 4 advantageously in the fully extracted or extended position, and which communicates with the closed cavity 3 when the annular sealing gasket 7 is in said nonsealing position; arranging the annular sealing gasket 7 in the non-sealing position, so as to put the closed cavity 3 in direct communication with said closed volume / space present at the mouth of cup-shaped body 5 ; feeding the pressuri zed gas into said closed volume / space so as to also pressurise said closed cavity 3 ; and then moving said annular sealing gasket 7 into said sealing position so as to fully isolate said closed cavity 3 from said closed volume / space present at the mouth of cup-shaped body 5 .

[0067] In addition, after having moved the annular sealing gasket 7 to the sealing position, the filling method of gas spring 1 with the pressuri zed gas also comprises the step of bringing back to ambient pressure the closed space / volume present at the mouth of cup-shaped body 5 , and next the step of removing / eliminating the closed volume / space from the mouth of cup-shaped body 5 .

[0068] More in detail , the step of arranging the annular sealing gasket 7 in the non-sealing position preferably entails arranging the plug body 6 within the cup-shaped body 5 in the temporary position, so as to align the annular sealing gasket 7 to the indentation 10 present inside the cup-shaped body 5 .

[0069] The step of moving the annular sealing gasket 7 into the sealing position, instead, preferably entails moving the plug body 6 within the cup-shaped body 5 to the final operating position, so as to misalign the annular sealing gasket 7 with respect to the indentation 10 present inside the cup-shaped body 5 .

[0070] In addition, the step of moving the plug body 6 inside the cup-shaped body 5 to the final operating position entails moving the plug body 6 away from the bottom of the cup-shaped body 5 , increasing the volume of the closed cavity 3 .

[0071] With reference to Figures 3 to 10 , in particular, the filling of gas spring 1 , or rather of the internal cavity 3 of casing 2 , with the pressuri zed gas is preferably carried out with the aid of a gas-springs filling machine 100 , which firstly comprises a rigid and advantageously made of metal material , machine body 101 which is provided with an oblongshaped blind cavity 102 that communicates with the outside through an opening 102a having a shape substantially complementary to the opening of cup-shaped body 5 .

[0072] In addition, the blind cavity 102 is preferably shaped / dimensioned so as to form an extension of the straight cavity of the cup-shaped body 5 that closes the mouth 102a of the same cavity .

[0073] More in detail , the blind cavity 102 is preferably substantially straight and advantageously also with a constant cross-section for substantially its entire length .

[0074] Preferably, the mouth 102a of blind cavity 102 of the machine body 101 is moreover adapted to substantially fluid- tight couple with the mouth of the cup-shaped body 5 of gas spring 1 .

[0075] In addition, the blind cavity 102 is shaped / dimensioned so as to form, together with the cup-shaped body 5 of the gas spring 1 that closes mouth 102a, a closed space / volume which is capable of accommodating / containing the plug body 6 and / or the pi ston-rod 4 of gas spring 1 , the latter advantageously in a fully extended or extracted position .

[0076] In other words , said closed space / volume preferably has such dimensions to be able to house / accommodate within itsel f at least the part of plug body 6 , or rather of the guide bushing, that protrudes from cup-shaped body 5 and / or the piston-rod 4 of gas spring 1 , the latter advantageously in the fully extended or extracted position .

[0077] In the example shown, in particular, the blind cavity 102 is preferably substantially cylindrical in shape , and its nominal diameter is substantially equal to the inner diameter of the cup-shaped body 5 .

[0078] In addition, the filling machine 100 preferably has at least one annular sealing gasket 103 , which is advantageously made of polymeric material , and is located on the machine body 101 so as to surround the mouth 102a of the blind cavity 102 and to interpose between the machine body 101 and the rim of the mouth of cup-shaped body 5 , in order to prevent the leakage of pressuri zed gas between the two elements .

[0079] More speci fically, the annular seal ing gasket 103 is preferably accommodated in an annular groove surrounding the mouth 102a of blind cavity 102 .

[0080] With reference to Figures 3 to 10 , the filling machine 100 furthermore comprises : a movable piston 104 advantageously made of metal material , which is housed / inserted in axially slidable manner within the blind cavity 102 , and is shaped so as to be able to rest its front part against the plug body 6 , or rather onto the guide bushing, that is inserted in the cavity of the cup-shaped body 5 arranged to close the mouth 102a of blind cavity 102 , advantageously without substantially touching the cup- shaped body 5 and optionally also the piston-rod 4 ; a preferably electrically- or hydraulically- operated, moving device 105 which is capable of axially moving the piston 104 inside the blind cavity 102 , to and from the mouth 102a ; and a pressuri zing system 106 , which communicates with the blind cavity 102 of machine body 101 and is adapted to feed, on command, nitrogen or other pressuri zed gas into the blind cavity 102 .

[0081] More in detail , the moving device 105 is preferably structured so as to be able to move the piston 104 within the blind cavity 102 , between a first and a second operating position . In the first operating position ( see Figure 5 ) , the piston 104 i s located more or less near the bottom of the blind cavity 102 , and the front part of piston 104 is located entirely inside the blind cavity 102 , at a given maximum distance from the mouth 102a . In the second operating position ( see Figures 4 , 7 and 8 ) , on the other hand, the piston 104 is located substantially at the mouth 102a of blind cavity 102 , and the front part of piston 104 j uts out cantilevered beyond the mouth 102a of blind cavity 102 , so as to penetrate into the cavity of the cup-shaped body 5 that closes the mouth 102a of blind cavity 102 .

[0082] In the second operative position, in addition, the front part of piston 104 protrudes cantilevered beyond the mouth 102a of blind cavity 102 , so as to arrange the plug body 6 , or rather the guide bushing, inside the cup-shaped body 5 , in said temporary position .

[0083] The pressuri zing system 106 , on the other hand, is preferably structured so as to be able , on choice and alternatively : feed nitrogen or other pressuri zed gas into the blind cavity 102 , in order to bring and maintain at a predetermined pressure the closed space / volume delimited by the blind cavity 102 and the cup-shaped body 5 of gas spring 1 ; or put the the blind cavity 102 in communication with the outside , in order to bring and maintain at ambient / external pressure the closed space / volume delimited by the blind cavity 102 and the cup-shaped body 5 of gas spring 1 .

[0084] Preferably, the front part of movable piston 104 is moreover provided with a receiving seat 104a, which is shaped so as to accommodate within itsel f the piston-rod 4 , advantageously in the fully extended or extracted position, of the gas spring 1 that closes the mouth 102a of blind cavity 102 .

[0085] In other words , the front part of movable piston 104 has a substantially rectilinear tubular structure that is adapted to rest on the plug body 6 , or rather on the guide bushing, of the gas spring 1 closing the mouth 102a of blind cavity 102 , while the piston-rod 4 of the same gas spring 1 freely penetrates inside said tubular structure .

[0086] More speci fically, the receiving seat 104a present on the front part of movable piston 104 preferably has a shape substantially complementary to that of the part of piston- rod 4 that protrudes cantilevered from the outer casing 2 of the gas spring 1 , advantageously when the piston-rod 4 is in the fully extended or extended position .

[0087] The filling machine 100 , in addition, is preferably also provided with a mechanical connecting member 107 , which is capable of coupling / securing the plug body 6 to the movable piston 104 , so that the plug body 6 moves axially within the cup-shaped body 5 together with the piston 104 in both directions .

[0088] More speci fically, the mechanical connecting member 107 is preferably adapted to rigidly fix / anchor the movable piston 104 to the piston-rod 4 of gas spring 1 in the fully extended or extended position .

[0089] Preferably, the filling machine 100 moreover comprises mechanical locking means 108 that are adapted to hold the cup-shaped body 5 of the gas spring 1 firmly in place on the machine body 101 , at closure of the mouth 102a of blind cavity 102 .

[0090] With reference to Figure 4 , in the example shown, in particular, the movable piston 104 is preferably structured to fluid-tight engage the blind cavity 102 , advantageously via the interposition of at least one annular sealing gasket preferably made of polymeric material .

[0091] The pressuri zing system 106 , in addition, is preferably structured as to feed the pressuri zed gas into the blind cavity 102 near the mouth 102a of the same cavity, i . e . between the piston 104 and the mouth 102a of blind cavity 102 .

[0092] More in detail , the pressuri zing system 106 preferably comprises : a pres suri zed-gas source 112 such as , for example , a high-pressure nitrogen cylinder or the like ; and a three- way valve 113 , which is adapted to put the blind cavity 102 of machine body 101 in communication, on choice and alternatively, with the a pressuri zed-gas source or with the external environment .

[0093] Even more speci fically, the three-way valve 113 has one inlet and two outlets , and is structured so as to put , on command, the valve inlet in direct communication alternately with each of the two outlets of the same valve .

[0094] The inlet of the three-way valve 113 communicates with the blind cavity 102 by means o f at least one connecting conduit 114 which is made reali zed in the machine body 101 , and ends in the blind cavity 102 preferably near the mouth 102a of the same cavity . The two outlets of the three-way valve 113 , on the other hand, communicate one with the pressuri zed-gas source 112 and the other with the external environment .

[0095] Preferably, the pressuri zing system 106 additionally comprises a pressure regulator 115 and / or a flow reducer 116 .

[0096] The pressure regulator 115 is preferably interposed between the pres suri zed-gas source 112 and the three-way valve 113 , and is advantageously adapted to bring / reduce the pressure of the gas flowing towards the three-way valve 113 to a predetermined value .

[0097] The flow reducer 115 , on the other hand, is preferably interposed between the three-way valve 113 and the external environment , and is advantageously adapted to limit the flowrate of the gas directed towards the outside .

[0098] With reference to Figures 3 and 4 , in turn, the moving device 105 preferably comprises : a straight shaft or rod 118 advantageously made of metal material , which extends within the blind cavity 102 coaxial or in any case parallel to the longitudinal axis L of the same cavity, and has its distal end firmly coupled / fixed to the rear part of movable piston 104 ; and a actuating member ( not visible in the figures ) which is capable of axially moving the straight rod 118 with respect to the machine body 101 .

[0099] Clearly, being the straight shaft or rod 118 integral with the movable piston 104 , the actuating member is also capable of moving the movable piston 104 back and forth within the blind cavity 102 .

[0100] In the example shown, in particular, the straight shaft or rod 118 is preferably fitted into the machine body 101 in pass-through manner, and is advantageously also connected to the machine body 101 by means of a screw-nut coupling . The actuating member, on the other hand, is preferably located outside the machine body 101 and preferably includes an electric- or hydraulic- actuator ( not visible in the figures ) that is mechanically connected / connectable to the straight shaft or rod 118 so as to rotate , on command, the straight shaft or rod 118 around its longitudinal axis , on choice clockwise or counterclockwise .

[0101] With reference to Figure 4 , the mechanical connecting member 107 , in turn, preferably comprises an anchoring screw advantageously made of metal material , which extends in pass- through manner in the body of movable piston 104 preferably while remaining coaxial or in any case parallel to the longitudinal axis L of blind cavity 102 and / or to the straight shaft or rod 118 , so that its threaded shank can j ut out from the front part of piston 104 and screw into the piston-rod body 4 , preferably within the receiving seat 104a . The mechanical locking means 108 , finally, are preferably adapted to press the cup-shaped body 5 o f the gas spring 1 in abutment against the machine body 101 .

[0102] More speci fically, mechanical locking means 108 preferably comprise a stationary j aw and a movable j aw .

[0103] The stationary j aw advantageously consists in the machine body 101 . The movable j aw, on the other hand, is arranged spaced in front of the mouth 102a of bl ind cavity 102 and is movable to and from the machine body 101 so as to clamp on the cup-shaped body 5 of the gas spring 1 .

[0104] In the example shown, in particular, the mechanical clamping means 108 preferably comprise : a platelike j aw 120 , which is arranged spaced in front of the mouth 102a of the blind cavity 102 , and is adapted to be arranged in abutment against the back of the cup-shaped body 5 of the gas spring 1 closing the mouth 102a of blind cavity 102 ; and a series of anchoring tie rods 121 , which are preferably arranged parallel to the longitudinal axis L of the blind cavity 102 , around the mouth 102a of blind cavity 102 , and are adapted to pull and secure the platelike j aw 120 rigidly to the machine body 101 .

[0105] With reference to Figures 5 to 10 , assuming that the plug body 6 , or rather the guide bushing, of the gas spring 1 is initially arranged in the final operating position, the filling method o f the cavity 3 o f gas spring 1 preferably comprises the steps of :

[0106] - arranging the gas spring 1 in abutment against the machine body 101 , so that the mouth of its cup-shaped body 5 matches and closes the mouth 102a of the blind cavity 102 , thus forming a closed space / volume that accommodates the plug body 6 and the piston-rod 4 of the same gas spring 1 ;

[0107] - bring the movable piston 104 in abutment against the plug body 6 , or rather the guide bushing, of the gas spring 1 ; - pushing the movable piston 104 towards the bottom of the cup-shaped body 5 , so as to move the plug body 6 , or rather the guide bushing, into the temporary position and, thus , arrange the annular sealing gasket 7 in the non-sealing position; feeding nitrogen or other pres suri zed gas into the blind cavity 102 , so as to bring the closed space / volume accommodating the plug body 6 and piston-rod 4 , and the adj acent closed cavity 3 of the gas spring 1 to a predetermined pressure ;

[0108] - moving the movable piston 104 towards the bottom of blind cavity 102 , so as to return the plug body 6 , or rather the guide bushing, to its final operating position and, as a consequence , the annular sealing gasket 7 in the sealing position;

[0109] - depressuri zing the blind cavity 102 of the fil ling machine 100 , so as to bring back to ambient pres sure the closed space / volume delimited by the machine body 101 and the outer casing 2 of the gas spring 1 ; and

[0110] - removing the gas spring 1 from filling machine 100 .

[0111] The displacement / return of the plug body 6 to its final operating position, in addition, may be performed or facilitated by a possible pressure di f ference between the front and rear of the movable piston 104 .

[0112] Preferably, before removing the gas spring 1 from the filling machine 100 , the filling method of the gas spring 1 preferably also comprises the step of moving the movable piston 104 away from the plug body 6 of the gas spring 1 closing the mouth 102a of the blind cavity 102 .

[0113] More in detail , with reference to Figures 5 and 6 , before moving the movable piston 104 towards the mouth 102 a of the blind cavity 102 , the filling method the gas spring 1 preferably compri ses the step of retaining, by means of the mechanical locking means 108 , the cup-shaped body 5 of the gas spring 1 firmly in abutment against the machine body 101 , at closure of the mouth 102a of the blind cavity 102 of machine body 101 .

[0114] In addition, with reference to Figure 6 , after bringing the movable piston 104 in abutment on the plug body 6 , the filling method of the gas spring 1 preferably also comprises the step of f ixing / securing, by means of the mechanical connecting member 107 , the piston-rod 4 and / or the plug body 6 , or rather the guide bushing, rigidly to the movable piston 104 .

[0115] With reference to Figures 7 , after having brought the movable piston 104 in abutment on the plug body 6 , the filling method of the gas spring 1 preferably comprises the step of further bringing the movable piston 104 closer to the mouth 102 of blind cavity 102 , so that the front part of piston 104 protrudes cantilevered from the mouth 102 of blind cavity 102 and penetrates into the cup-shaped body 5 , moving the plug body 6 , or rather the guide bushing, to said temporary position .

[0116] With reference to Figure 8 , after having moved the plug body 6 , or rather the guide bushing, to the temporary position, the fil ling method of the gas spring 1 preferably comprises the step of operating the pressuri zing system 106 , or rather the three-way valve 113 , so as to introduce nitrogen or other pressuri zed gas within the closed volume / space delimited by the machine body 101 and the gas spring 1 .

[0117] Since the annular sealing gasket 7 is in the non-sealing position, the pressuri zed gas fed into the blind cavity 102 can also reach and fill the closed cavity 3 of gas spring 1 .

[0118] With reference to Figure 9 , after having filled the cavity 3 of casing 2 with the pressuri zed gas , the filling method of the gas spring 1 preferably comprises the step of moving the movable piston 104 away from the cup-shaped body 5 , so as to bring the plug body 6 , or rather the guide bushing, back into its final operating position, i . e . in abutment against the Seeger ring, in order to fluid-tight seal the cavity 3 of gas spring 1 .

[0119] With reference to Figure 10 , after having isolated / separated the closed cavity 3 of gas spring 1 from the blind cavity 102 of machine body 101 , the filling method of gas spring 1 preferably comprises the step of operating the pressuri zing system 106 , or rather the three-way valve 113 , so as to bring the blind cavity 102 back to ambient pressure ; and then the step of detaching / removing the gas spring 1 from the machine body 101 .

[0120] Before detaching the gas spring 1 from the filling machine 100 , the filling method of gas spring 1 preferably moreover comprises the step of disengaging / uncoupling the piston-rod 4 and / or the plug body 6 from the movable piston 104 ; and / or the step of disengaging / releasing the gas spring 1 from the machine body 101 .

[0121] The advantages connected to the above-described filling method of gas spring 1 are remarkable .

[0122] The new filling method described above , in fact , allows to eliminate the one-way valve thus reducing the production costs of the gas spring . The one-way valve of the gas spring, indeed, is one of the most expensive and di f ficult components to assemble .

[0123] In the gas spring 1 , thus , the cup-shaped body 5 advantageously lacks any additional through duct that connects the closed cavity 3 , or rather the variable-volume closed chamber, with the outside and, moreover, accommodates inside itsel f a one-way valve oriented so as to al low the pressuri zed gas to exclusively flow towards said closed cavity 3 .

[0124] Preferably, the bottom wall and the lateral wall of the cup-shaped body 5 extend without interruptions .

[0125] Finally, it is clear that modi fications and variations may be made to the gas spring 1 , the filling method of gas spring 1 , and the filling machine 100 without departing from the scope of the present invention .

[0126] For example , in place of the bypass notch or indentation 10 , the cup-shaped body 5 may have an annular groove with a width advantageously greater than the nominal height h of the annular sealing gasket 7 .

[0127] In addition, the positions of the annular sealing gasket 7 and the bypass notch or indentation 10 may be reversed .

[0128] In other words , the annular sealing gasket 7 may be integral with the cup-shaped body 5 , or rather may be accommodated within an annular groove made on the inner lateral surface o f the closed cavity 3 of cup-shaped body 5 , while the bypass notch or indentation 10 may be reali zed on the outer periphery of plug body 6 , or rather of the guide bushing .

[0129] In addition, the piston-rod 4 may consist of a straight rod with substantially constant cross- section, which is preferably substantially cylindrical in shape and has , at the axial end permanently located within the closed cavity 3 , a protruding annular flange that is adapted to prevent the straight rod from being completely extracted from the casing 2 .

[0130] Furthermore , with reference to Figure 11 , in a di f ferent embodiment of the spring 1 , instead of engaging the plug body 6 , the piston-rod 4 is inserted in pass-through and axially slidable manner in the bottom wall of the cup-shaped body 5 . In addition, the piston-rod 4 is preferably moreover fitted into the bottom wall of cup-shaped body 5 substantially fluid-tight .

[0131] More in detail , in this embodiment , the piston-rod 4 is preferably fluid-tight coupled to the cup-shaped body 5 via an annular sealing gasket 9 ' advantageously made of polymeric material , which is interposed between the piston-rod 4 and the cup-shaped body 5 and is adapted to prevent the leakage / passage of pressuri zed gas in the interstitial space between the piston-rod 4 and the cup-shaped body 5 . In other words , the bottom wall of cup-shaped body 5 is preferably provided with a straight through hole advantageously circular in shape , which preferably has a cross-section substantially complementary to that of the piston-rod 4 , and is engaged in pass-through and axially slidable manner by the piston-rod 4 .

[0132] The plug body 6 , on the other hand, preferably consists of a breech advantageously substantially cylindrical in shape , which preferably has a monolithic structure and is preferably made of metal material .

[0133] The annular seal ing gasket 7 , in turn, is preferably accommodated within an annular groove made on the outer surface of the breech .

[0134] In other words , in this embodiment the cup-shaped body 5 is provided with two access apertures to the inner cavity, preferably arranged on opposite sides of the same cup-shaped body 5 and advantageously also aligned with each other . The first access opening of cup-shaped body 5 is substantially fluid-tight closed by the plug body 6 together with the annular sealing gasket 7 . The second access opening of cupshaped body 5 , on the other hand, is substantially fluid- tight closed by the piston-rod 4 advantageously in combination with the annular sealing gasket 9 ' .

[0135] In this case , the platelike j aw 120 of the filling machine 100 is preferably provided with a blind or through seat 120a that is adapted to be engaged by the piston-rod 4 of the gas spring 1 .

[0136] Assuming that the plug body 6 , or rather the breech, of the gas spring 1 is initially in the final operating position wherein it closes the mouth of cup-shaped body 5 , the filling method of the cavity 3 of gas spring 1 preferably comprises the steps of :

[0137] - placing the gas spring 1 in abutment against the machine body 101 , so that the mouth of its cup-shaped body 5 matches and closes the mouth 102a of the blind cavity 102 , forming a closed space / volume that optionally may accommodate at least part of plug body 6 ;

[0138] - bringing the movable piston 104 in abutment against the plug body 6 , or rather the rear part of the breech, of the gas spring 1 ;

[0139] - pushing the movable piston 104 towards the bottom of the cup-shaped body 5 , so as to move the plug body 6 , or rather the breech, into the temporary position and, thus , arrange the the annular seal ing gasket 7 in the non-sealing position; feeding nitrogen or other pres suri zed gas into the blind cavity 102 , so as to bring the closed space / volume accommodating the plug body 6 and the adj acent closed cavity 3 of gas spring 1 to a predetermined pressure ;

[0140] - moving the mobile piston 104 towards the bottom of the blind cavity 102 , so as to bring the plug body 6 , or rather the breech, back to its final operating position and, thus , arranging the annular sealing gasket 7 in the sealing position;

[0141] - depressuri zing the blind cavity 102 of the filling machine 100 , so as to bring back to ambient pres sure the closed space / volume delimited by the machine body 101 and the outer casing 2 of gas spring 1 ; and finally

[0142] - removing the gas spring 1 from the filling machine 100 .

[0143] Preferably, after having brought the movable piston 104 in abutment against the plug body 6 , or rather the rear part of the breech, the filling method of gas spring 1 preferably also comprises the step of fixing / securing, by means of the mechanical connecting member 107 , the plug body 6 , or rather the breech, rigidly to the movable piston 104 .

Claims

CLAIMS1. Filling method of a gas spring (1) that comprises: an outer casing (2) which is internally provided with a closed cavity (3) ; and a piston-rod (4) , which is inserted in an axially slidable manner in the outer casing (2) , and is structured so as to form / delimit , together with said closed cavity (3) , a variable-volume closed chamber adapted to contain a pressurized gas; said casing (2) comprising: a cup-shape body (5) ; a plug body (6) , separate and distinct from the cup-shape body (5) , which is at least partially inserted in the cup-shape body (5) so as to delimit said closed cavity (3) ; and at least one annular sealing gasket (7) , which is interposed between the plug body (6) and the cup-shape body (5) and is adapted to prevent the leakage / passage of the pressurized gas between the cup-shape body (5) and the plug body (6) ; said filling method being characterized by comprising the steps of: arranging the annular sealing gasket (7) inside the cup-shape body (5) in a non-sealing position, in which the annular sealing gasket (7) allows the passage of gas from and towards said closed cavity (3) ; introducing the pressurized gas into the closed cavity (3) causing it to pass into the interstitial space between said cup-shape body (5) and said plug body (6) ; and finally arranging / moving the annular sealing gasket (7) into a sealing position in which the annular sealing gasket (7) isolates / seals said closed cavity (3) in a fluid-tight manner.

2. Filling method of a gas spring according to Claim 1, wherein the step of introducing the pressurized gas into the closed cavity (3) entails: creating / forming, at the inlet of the cup-shape body (5) , a closed space / volume that communicates with the closed cavity (3) when the annular sealing gasket (7) is in said non-sealing position; placing the annular sealing gasket (7) in the non-sealing position, so as to put the closed cavity (3) in direct communicationwith said closed volume / space present at the inlet of the cup-shape body (5) ; feeding the pressurized gas into said closed volume / space so as to also pressurize said closed cavity (3) ; and moving the annular sealing gasket (7) into the sealing position so as to completely isolate the closed cavity (3) from said closed volume / space present at the inlet of the cup-shape body (5) .

3. Filling method of a gas spring according to Claim 2, wherein the step of introducing the pressurized gas into the closed cavity (3) additionally entails, after having moved the annular sealing gasket (7) into said sealing position, the step of returning said closed volume / space to ambient pressure, and then the step of removing / eliminating said closed volume / space from the inlet of the cup-shape body (5) .

4. Filling method of a gas spring according to Claim 2 or 3, wherein the annular sealing gasket (7) moves together with the plug body (6) , and wherein the step of placing the annular sealing gasket (7) in the non-sealing position entails arranging the plug body (6) inside the cup-shape body (5) in a temporary position in which said plug body (6) aligns said annular sealing gasket (7) to a bypass recess (10) , which is present on the inner surface of the cup-shape body (5) at a predetermined distance both from the bottom and from the mouth of said cup-shape body (5) .

5. Filling method of a gas spring according to Claim 2, 3 or 4, wherein the annular sealing gasket (7) moves together with the plug body (6) , and wherein the step of placing the annular sealing gasket (7) in the sealing position entails arranging the plug body (6) inside the cup-shape body (5) , in a final operating position in which said plug body (6) misaligns said annular sealing gasket (7) from a bypass recess (10) that is present on the inner surface of the cupshape body (5) at a predetermined distance both from the bottom and from the mouth of said cup-shape body (5) .

6. Filling method of a gas spring according to claim 5, wherein the plug body (6) is in the final operating position when it is located substantially at the mouth of the cupshape body (5) .

7. Filling method of a gas spring according to Claim 5 or 6, wherein the plug body (6) , when placed in the final operating position, arranges the annular sealing gasket (7) between said bypass recess (10) and the mouth of the cupshape body (5) .

8. Filling method of a gas spring according to Claim 5, 6 or 7, wherein the step of moving the plug body (6) within the cup-shape body (5) , into the final operating position, enatils moving the plug body (6) away from the bottom of the cup-shape body (5) .

9. Filling method of a gas spring according to any one of the preceding claims, wherein the piston-rod (4) is inserted in axially slidable manner into the plug body (6) .

10. Filling machine (100) for gas springs that comprise: a cup-shape body (5) ; a plug body (6) , separate and distinct from said cup-shape body (5) , which is at least partially inserted in the cup-shape body (5) so as to form a closed cavity (3) ; and a piston-rod (4) , which engages said plug body (6) or said cup-shape body (5) in an axially slidable manner, and is structured so as to form / delimit , together with said closed cavity (3) , a variable-volume closed chamber adapted to contain a pressurized gas; said filling machine (100) being characterized by comprising: a machine body (101) which is provided with an oblong-shaped blind cavity (102) that communicates with the outside through a mouth (102a) having a shape substantially complementary to the mouth of the cup-shape body (5) , and is adapted to form, at the mouth of said cup-shape body (5) , a closed space / volume ; a movable piston (104) , which is housed / inserted in axially slidable manner within said blind cavity (102) , and is shaped so as to be able to rest itsfront part onto the plug body (6) present in the cavity of the cup-shape body (5) ; a moving device (105) , which is capable of axially moving the piston (104) inside the blind cavity (102) , away from and towards the mouth (102a) of said blind cavity (102) ; and a pressurizing system (106) that communicates with said blind cavity (102) of the machine body (101) and is adapted to feed a pressurized gas into said blind cavity (102) .

11. Filling machine according to Claim 10, characterized by additionally comprising a mechanical connection member (107) that is adapted to connect the plug body (6) present in the cavity of the cup-shape body (5) to said movable piston (104) , so that the plug body (6) moves axially inside the cup-shape body (5) together with the movable piston (104) in both directions.

12. Filling machine according to Claim 10 or 11, characterized by additionally comprising mechanical locking means (108) which are adapted to retain the cup-shape body (5) of the gas spring (1) firmly in abutment on the machine body (101) , at closure of the mouth (102a) of said blind cavity (102) .

13. Filling machine according to Claim 10, 11 or 12, wherein said pressurizing system (106) is structured so as to be able to, selectively and alternatively, feed the pressurized gas into the blind cavity (102) of the machine body (101) , or put said blind cavity (102) in communication with the outside .

14. Filling machine according to Claim 10, 11, 12 or 13, wherein the front part of the movable piston (104) is provided with a receiving seat (104a) , which is shaped so as to accommodate inside itself the piston-rod (4) of the gas spring (1) that closes the mouth (102a) of the blind cavity (102) .

15. Filling machine according to any one of Claims from 10 to 14, wherein the mouth (102a) of said blind cavity (102)is adapted to couple in a substantially fluid-tight manner to the mouth of the cup-shape body (5) of the gas spring (1) that closes the same blind cavity (102) .

16. Filling machine according to any one of Claims from 10 to 15, wherein said blind cavity (102) is shaped / dimensioned so as to form an extension of the cavity of the cup-shape body (5) .

17. Filling machine according to any one of Claims from 10 to 16, wherein said blind cavity (102) is shaped / dimensioned so as to form, together with the cup-shape body (5) of the gas spring (1) that closes the mouth (102a) of the same blind cavity (102) , a closed space / volume that is capable of accommodating / containing the plug body (6) and / or the piston-rod (4) of the gas spring (1) .

18. Gas spring (1) comprising: an outer casing (2) which is internally provided with a closed cavity (3) ; and a piston- rod (4) , which is fitted in axially slidable manner in the outer casing (2) , and is structured so as to form / delimit , together with said closed cavity (3) , a variable-volume closed chamber adapted to contain a pressurized gas; said casing (2) comprising: a cup-shape body (5) ; a plug body (6) , separate and distinct from the cup-shape body (5) , which is at least partially inserted in the cup-shape body (5) so as to delimit said closed cavity (3) ; and at least one annular sealing gasket (7) , which is interposed between the plug body (6) and the cup-shape body (5) , and is adapted to prevent the leakage / passage of the pressurized gas between the cup-shape body (5) and the plug body (6) ; said gas spring (1) being characterized in that the cupshape body (5) has, on its inner lateral surface, a bypass recess (10) which is spaced both from the bottom and from the mouth of the cup-shape body (5) , and in that the annular sealing gasket (7) is axially movable inside the cavity of the cup-shape body (5) between a sealing position in which the annular sealing gasket (7) is staggered / misaligned withrespect to said bypass recess (10) , and a non-sealing position in which the annular sealing gasket (7) is aligned with said bypass recess (10) .

19. Gas spring according to Claim 18, wherein the annular sealing gasket (7) is f itted / mounted on the plug body (6) so as to move axially only together with said plug body (6) , and wherein the plug body (6) is axially movable inside the cup-shape body (5) between a final operating position in which the plug body (6) arranges and keeps said annular sealing gasket (7) staggered / misaligned with respect to said bypass recess (10) so as to seal the closed cavity (3) in a fluid-tight manner, and a temporary position in which the plug body (6) aligns said annular sealing gasket (7) with the recess (10) so as to allow the passage of gas in the interstitial space between the cup-shape body (5) and the plug body ( 6 ) .

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