Gas spring and associated safety system

Abstract

A gas spring (200) is described, comprising a guide (2) having an outer surface (212), a slider (1) defining, with the guide (2), at least one chamber (11) containing pressurized gas, the slider (1) being slidably connected to the guide (2) so as to have an extended maximum stroke, wherein the guide (2) is partially extracted from the slider (1), and a compressed maximum stroke, characterized in that it comprises a bushing (3) located between the slider (1) and the guide (2), the bushing comprising sealing means for sealing the chamber (11) and being removably coupled so as to move integrally with the slider (1) up to the maximum stroke, in such a way that, when the slider (1) slides with respect to the guide (2) beyond the maximum stroke, the bushing (3) is disengaged from the slider (1), thus eliminating the seal of the chamber (11).

Description

Technical Field

[0001] This invention relates to gas springs and related safety systems. Background Technology

[0002] This invention is part of a broader field of production of gas springs (also known as nitrogen cylinders).

[0003] Gas springs typically include:

[0004] - A fixed external body, such as a cylinder or casing;

[0005] - Moving parts, also known as levers;

[0006] - Possible guiding devices for the rod;

[0007] - One or more sealing elements;

[0008] - The component that introduces gas into the cylinder is also called the filling valve.

[0009] Currently, one of the most important aspects in this field is the safety of these mechanical devices.

[0010] As is well known, the increased efficiency of thrust components over time typically leads to an increase in the maximum load that a gas spring can support. This is almost always achieved through an increase in the gas pressure within the gas spring's components themselves.

[0011] Modern gas springs can withstand initial pressures of up to 150-180 bar, and this must be properly considered by designers, manufacturers and / or maintenance personnel, and users as part of their activities.

[0012] However, it is necessary to avoid damage or injury caused by the gas spring itself, and special attention must be paid to defects that frequently affect components but do not immediately lead to failure.

[0013] For example, minor defects and / or defects that cannot be detected by visual inspection do not allow users to identify defective gas springs, or at least not to take preventive measures such as replacing damaged parts or even sending the workpiece for repair.

[0014] Another problem arises from the fact that when a known gas spring is currently in a compressed state, the piston creates additional volume on the opposite side of the chamber between the piston itself and the upper guide band. This creates a negative pressure in the space, which can absorb oil or other substances that reduce the efficiency of the gas spring by decreasing the useful volume, and may even damage the gas spring over time.

[0015] The reduction in oil volume also increases the gas pressure inside the chamber, which can be very dangerous during operation.

[0016] Furthermore, considering that gas springs are typically subjected to cyclic loads, the formation of undesirable cracks makes them particularly susceptible to fatigue failure.

[0017] All these problems often lead to accidents and sudden incidents, posing a considerable danger to personnel and operators near a broken gas spring. The consequences of such accidents can be very serious, causing varying degrees of injury, or even death.

[0018] Because the evolution of these phenomena is difficult to assess, operators in the industry strongly believe that it is necessary for the industry to ensure adequate safety conditions, regardless of the technology they use for various inspections.

[0019] Therefore, it is crucial to use investigative techniques employed before putting gas springs into operation to prevent accidents caused by sudden and unpredictable damage.

[0020] However, this method is not always easy to implement, and it is not without errors or oversights.

[0021] Once a gas spring is put into continuous operation, it is not uncommon for it to suffer damage and degradation due to normal wear or use under inappropriate or unforeseen conditions, or due to completely accidental events.

[0022] Such dangerous injuries can occur, for example, due to an unwanted impact, and if not identified in time, can even lead to serious accidents.

[0023] As a first particularly relevant example, one can consider the case of a gas spring at the end of its compression phase.

[0024] In this case, when the gas spring is configured near the bottom dead center, that is, in a configuration where the sliding element inside the hollow housing containing the gas is close to the inner wall of the housing itself, it is desirable to avoid contact between the two main parts of the gas spring.

[0025] Alternatively, the opposite scenario can be considered, with the gas spring positioned towards the end of the expansion phase and close to the top dead center.

[0026] Typically, some mechanisms are incorporated into gas springs to prevent the two sliding elements from slipping off each other, such as pistons equipped with locking heads, thus preventing the gas spring's stroke from continuing beyond its maximum extension limit.

[0027] However, in the event of damage and / or malfunction of these components, the risk of the sliding element detaching and all associated consequences will increase significantly.

[0028] Another drawback of the existing solution is that once the gas spring is assembled, it is not easy to check for cracks in the components designed to ensure safety located in the gas-containing chamber, except after the internal pressure of the gas spring reaches atmospheric pressure and it is disassembled.

[0029] This operation involves extended operating time, and sometimes the gas spring may become unusable after inspection. Therefore, it is generally preferable to directly replace the suspected faulty gas spring, even if there is no definitive evidence of a fault. This dangerous situation may be more likely to occur if the gas spring is designed to prevent disengagement between the sliding element and / or the sealing element.

[0030] Gas springs may break or crack after collisions and / or unwanted contact between their sliding or sealing parts. Even minor breaks or cracks may not be detected by routine visual inspection.

[0031] However, if a gas spring appears intact and continues to bear pressure, it will cause the fracture to propagate, making it extremely dangerous to use.

[0032] The technical device described herein causes the sealing of the sliding element to be immediately and completely lost, and the sliding element to be disengaged, thereby preventing the continued use of the potentially damaged gas spring and the therefore dangerous gas spring.

[0033] Examples of known gas springs suffering from the above-mentioned drawbacks can be found in patent documents EP3051 173A2, EP2778465A1 and EP3236102A1.

[0034] The gas springs described in these patent documents are manufactured in a way that prevents the sliding element from detaching itself, thus they cannot guarantee that the gas will completely escape from the chamber.

[0035] All existing locking rings are designed to remain elastically expanded within their respective initial seats, and the bushings located in the middle position between the two main sliding elements prevent the locking rings from shifting and thus disengaging the elements themselves.

[0036] It is also conceivable that when the overstroke of the compression phase is reached, one or more components will certainly break, exposing the surrounding environment and personnel, as well as the gas spring itself, to dangers caused by the ejection of debris or by possible interference between the debris and moving parts located near the gas spring.

[0037] Therefore, it is crucial to equip the gas springs currently in use with a second safety mechanism that can function in the event of a failure of the first safety mechanism and can prevent component failure. Summary of the Invention

[0038] The main objective of this invention is to overcome the aforementioned shortcomings of the prior art.

[0039] Specifically, the object of the present invention is to provide a gas spring equipped with a safety system that intervenes if a safety value is exceeded regarding one or more operating parameters.

[0040] These parameters can be, for example, the maximum and / or minimum permissible extension of the gas spring stroke.

[0041] Furthermore, another objective of the present invention is to overcome the problems of increased pressure and oil suction, which are caused by low pressure formed in the cavity inside the gas spring during compression.

[0042] Finally, the object of this invention is to provide a gas spring that is easy to manufacture and install.

[0043] Therefore, the object of the present invention is to provide a gas spring equipped with a safety system, the gas spring comprising: a guide member having an outer surface; a slider member defining, together with the guide member, at least one chamber for containing pressurized gas, the slider member being slidably connected to the guide member to have a minimum stroke of expansion, wherein the guide member is partially withdrawn from the slider member, and a maximum stroke of compression; the gas spring further comprising a bushing disposed between the slider member and the guide member, the bushing comprising a sealing device for sealing the chamber and being detachably coupled to move integrally with the slider member up to the maximum stroke, such that when the slider member slides relative to the guide member beyond the maximum stroke, the bushing disengages from the slider member, thereby eliminating the sealing of the chamber.

[0044] According to a preferred embodiment, the slider has a groove formed on its inner surface, and the bushing has a slot facing the groove, thereby providing a seat for receiving a locking element; when the slider slides relative to the guide beyond the maximum stroke of compression, the reciprocating position of the slot relative to the groove changes, causing the locking element to leave the seat, thereby disengaging the bushing from the slider and eliminating the airtightness of the chamber.

[0045] Furthermore, the groove may have a first edge near the first opening of the first chamber of the slider, and a second edge that tapers in a direction opposite to the first edge, so that the locking element moves out of its seat when the bushing slides relative to the slider.

[0046] In this configuration, the bushing has a lower surface that extends from the first opening of the first chamber by at least half the width of the cross-section of the locking element, thereby ensuring that the locking element is displaced from the recess, thereby disengaging the bushing and eliminating the airtightness of the chamber.

[0047] According to a further preferred embodiment, the gas spring may include a safety element to prevent the slider from disengaging from the guide when the slider slides beyond the minimum stroke of expansion.

[0048] Alternatively, the safety element can be arranged to protrude from the outer surface of the guide.

[0049] In addition, the guide may have a circular seat corresponding to the outer surface, and the safety element may be a Seeger ring or a stop ring housed in the circular seat so as to extend relative to the outer surface of the guide.

[0050] The guide may also have a second opening, and a safety element may be arranged on the outer surface of the guide and at the second opening.

[0051] According to a further embodiment, the bushing includes a lip on the relevant inner surface, which is designed to interfere with the safety element when the slider reaches its minimum stroke.

[0052] In addition, the gas spring may include an end stop having a rod integral with the slider and restricted from sliding through a second opening in the guide; and a head inserted into the guide and configured to abut against an abutment defined by the second opening, thereby preventing separation between the slider and the guide.

[0053] Finally, the gas spring may include devices for sealing the chamber and / or guiding devices for the reciprocating sliding of the guide and the bushing, located between the bushing itself and the guide and / or between the bushing and the slide. Attached Figure Description

[0054] The invention has been described by way of example and without limiting the scope thereof, with reference to the accompanying drawings, wherein:

[0055] Figure 1 This is a front view of a first embodiment of the gas spring according to the present invention;

[0056] Figure 2 yes Figure 1 A plan view of the gas spring;

[0057] Figure 3 It shows Figure 1 and Figure 2 A cross-sectional view of the gas spring along line AA;

[0058] Figure 4 It shows Figure 3 Details of the sectional view;

[0059] Figure 5 This is a front view of a second embodiment of the gas spring according to the present invention;

[0060] Figure 6 yes Figure 5 A plan view of the gas spring;

[0061] Figure 7 It shows Figure 5 and Figure 6 A cross-sectional view of the gas spring along line AA;

[0062] Figure 8 It shows Figure 7 A cross-sectional view of the gas spring during its overstroke phase;

[0063] Figure 9 It shows Figure 7 A cross-sectional view of a gas spring during the compression phase;

[0064] Figure 10 shows Figure 7 A cross-sectional view of a gas spring at the end of its compression phase.

[0065] Figure 11 shows Figure 7 A cross-sectional view of the gas spring during its overstroke phase in the compression stage;

[0066] Figure 12 shows a detailed cross-sectional view of the gas spring of Figure 11;

[0067] Figure 13 The cross-sectional view of the gas spring in Figure 11 after an overstroke occurs during the compression phase, resulting in bushing separation.

[0068] Figures 14A-14C are cross-sectional views of a third embodiment of a safety system according to the present invention applied to a conventional gas spring.

[0069] Similar parts will be indicated by the same reference numerals in the various figures. Detailed Implementation

[0070] refer to Figure 1-3 The gas spring according to the invention is generally designated as 100 and includes a first hollow element or slider 1 in which a first chamber 11 is formed, the first chamber being defined by a first bottom wall 110, an inner side surface 111 and a first opening 10.

[0071] The first bottom wall 110 is part of the closure element 400, which is necessary in this embodiment to allow the assembly of the components forming the gas spring 100, as will be described in more detail below.

[0072] The sealing between the sealing element 400 and the body of the sliding element 1 is ensured by a gasket 401 located at their contact point.

[0073] The gas spring 100 also includes a second element or guide 2, which is also hollow and has a second chamber 21, which is defined by a second bottom wall 210, a second inner side surface 211 and a second opening 20.

[0074] The bottom wall 210 is part of the reversible coupling disc 300, which is then assembled to the guide 2 to keep the second chamber 21 accessible until the gas spring 100 is fully formed.

[0075] According to the first embodiment, the inner side surface 111 of the slider 1 is at least partially in contact with the outer surface 212 of the guide 2, and this contact is almost always made by means of a washer or other auxiliary element (not shown), such as a so-called guide bar or scraper bar.

[0076] At its end opposite to the opening 20, the guide member 2 has a safety stop 22 provided on the outer surface 212 of the defining chamber 21. Figure 3 In this case, the safety stop 22 is a support base for the gas spring, which has an upper surface 220.

[0077] The slider 1 and guide 2 are manufactured such that the guide 2 can be inserted into the slider 1 and can slide within the chamber 11, for both maximum and minimum extension configurations only.

[0078] Now for reference Figure 3 , Figure 4 and Figure 8 A first housing 130 for accommodating, for example, a gasket is formed along the circumference of the inner side surface 111 of the chamber 11 and is located near the first opening 10; however, according to other variant embodiments of the gas spring, a greater number of housings may be provided for other accessories.

[0079] The chamber 130 is defined in its portion facing the opening 10 of the cavity 11 by a lower projection profile or lower lip 132 that protrudes relative to the inner side surface 111 (in Figure 4 (See in the middle).

[0080] A circular seat 23 is formed on the outer surface 212 of the guide member 2 near the opening 20.

[0081] The circular seat 23 is used to accommodate the first safety element 230, such as a conventional stop ring.

[0082] The gas spring 100 further includes an end stop 12, such as a piston, which is located in the first chamber 11 and integral with the slider 1.

[0083] The end stop 12 is provided with a rod 120 fixed to the bottom wall 110 of the chamber 11, and a head 121 having a larger diameter than the rod 120 and inserted into the second chamber 21 of the guide 2.

[0084] Rod 120 is confined within the second opening 20.

[0085] The head 121 has an upper surface 122 and a lower surface 123.

[0086] In this way, in the slider 1-guide 2 system, the two sliding elements are constrained to translate along the direction of the axis of symmetry X of the gas spring 100.

[0087] The head 121 (especially its lower surface 123) is used to prevent the two elements from sliding relative to each other until they are released.

[0088] For this purpose, the inner wall 211 of the chamber 21 has a small hole (or inner diameter) section at the opening 20, which has a first abutment surface or step 124 extending along the entire circumference of the opening 20.

[0089] During operation of the gas spring, the abutment surface 124 serves as the upper limit of the relative sliding of elements 1 and 2; the lower surface of the abutment step 124 of the head 121 of the end stop 12 prevents the gas spring from expanding and thus prevents its movement in the axial direction.

[0090] Observing the circular seat 23, its position on the outer surface 212 is such that when the gas spring is in normal operation, the safety element 230 housed in the circular seat 23 will not interfere with the sliding of the slider 1.

[0091] The head 121 of the end stop 120 effectively prevents the slider 1 from rising freely to avoid contact between the protruding profile 132 and the safety element 230 located in the circular seat 23.

[0092] When this is not the case, for example, due to the breakage of an internal spring component, the stroke range exceeds the maximum permissible limit.

[0093] The safety element 230 located in the circular seat 23 contacts the lip 132 after the slider 1 exceeds the minimum stroke, thereby bringing the sealing device to a position where the seal between the guide 2 and the slider 1 is no longer guaranteed.

[0094] In this way, the drawbacks of the prior art are avoided, according to which damage to the hidden parts of the gas spring may not be immediately apparent and remains dangerously hidden for a longer or more prolonged period before failure is achieved.

[0095] refer to Figure 5-13A second embodiment of the gas spring according to the present invention will now be described.

[0096] Equivalent parts and components in the different embodiments shown and / or described are indicated by the same reference numerals.

[0097] Figure 5-8 The gas spring 200 shown includes a cylinder or slider 1 and a piston or guide 2, which are constructed identically to those in the first embodiment.

[0098] Embodiments of the gas spring 200 also include an end stop 12, which is similar to the end stop in the above-described variant.

[0099] On the inner side surface 111 of the slider 1, a groove 32 is formed near the opening 10. The groove is defined by a first edge or lower edge 320 and a second edge or upper edge 321, and their outlines are asymmetrical.

[0100] In fact, the lower edge 320 is the traditional shoulder.

[0101] On the other hand, the upper edge 321 has a profile that tapers slightly toward the interior of the chamber 11; in other words, the diameter of the inner sidewall 111 gradually increases as the surface of the groove 32 moves away from the bottom wall 110 and toward the opening 10.

[0102] Thus, an initial open profile is obtained, but the profile ends at a shoulder indicated by the lower edge 320.

[0103] Furthermore, according to this embodiment of the gas spring, the diameter of the first opening 10 is larger than that in the first embodiment described, so as to allow the bushing 3 to be introduced into the gap, which is thus created between the inner side surface 111 of the slider 1 and the outer surface 212 of the guide 2.

[0104] In the first case, chambers 11 and 21 are connected, which advantageously allows for an increase in the internal sealing surface of the gas spring and a significant reduction in pressure during operation, thereby improving the safety of the gas spring itself.

[0105] The inner surface or wall 311 of the bushing 3 contacts the outer surface 212 of the guide 2 and is provided with multiple chambers:

[0106] - A first chamber 130, which is defined by a first protruding profile or lip 131 in its portion facing the bottom wall 110 and by a second protruding profile or lip 132 in its portion facing the opening 10.

[0107] - The second chamber 140 and the third chamber 150 are arranged side by side with the first chamber 130 and are set at a variable distance according to design requirements.

[0108] These chambers are also used to house auxiliary components (not shown), such as sealing devices for gases, guides to facilitate and guide sliding between elements, and scraping devices for cleaning exposed surfaces and / or protecting them from dust or external substances.

[0109] The profiles 131 and 132 of bushing 3 have the same function as the upper limit of the stroke between sliding elements 1 and 2, which is in Figure 8 This is shown more clearly in the text.

[0110] On the other hand, the outer surface or wall 312 of the bushing 3 contacts the inner side surface 111 of the slider 1.

[0111] The following is formed on the outer surface 312:

[0112] - A fourth chamber 40 is designed to house a suitable sealing device (not shown) to seal against the inner side surface 111 of the slider 2, which prevents gas from escaping from the chamber 11;

[0113] - The fifth chamber 31 is defined at the bottom by the lower surface 35 of the bushing 3 itself and at the top by a joint or chamfer, and its outline ends with a slot 310. The bushing 3 is connected to the slider 1 itself near the opening 14, and it is manufactured such that the slot 310 of the bushing and the groove 32 of the slider 1 are adjacent to each other and face each other.

[0114] In this way, the slot 310 and the groove 32 together define a seat for receiving the locking element 30, which makes the bushing 3 integral with the slider 1; such locking device may be, for example, a harmonic or elastic steel ring.

[0115] In fact, during normal operation of the gas spring 200, the pressure of the gas contained in the chamber 11 can push the bushing 3 in the direction of the opening 10, and may cause the bushing to separate from the slider 1.

[0116] In fact, the presence of the lower edge 320 of the groove 32 and the locking element 30 clamped by the slot 310 locks the bushing 3 and the slider 1 together.

[0117] Advantageously, the locking element 30 can have a reduced size relative to the prior art because it does not bear dynamic loads during the operation of the gas spring and is only used to keep the two elements connected together.

[0118] Existing solutions utilize larger ring or threaded elements to withstand potentially high-pressure stresses.

[0119] Therefore, this variant of the gas spring operates in a conventional manner during use.

[0120] In the event of overstroke during the expansion phase, the safety mechanism described above in the first embodiment intervenes, and its operation is as follows: Figure 8 As shown.

[0121] If necessary, gas springs without this first safety mechanism can also be manufactured.

[0122] refer to Figures 9 to 13 The operation of a second embodiment of the safety device according to the invention is now shown, in the case of overstroke during the compression phase of the gas spring, and corresponding to the so-called bottom dead center configuration.

[0123] As mentioned above, during the normal use of the gas spring, it is preferable that the two main sliding elements do not come into contact with each other.

[0124] For example, this is achieved by carefully adjusting the movement of the elements that interact with the gas spring itself, so as not to generate excessive stress that would lead to over-compression, and therefore not to cause undesirable contact between the components of the gas spring itself.

[0125] like Figures 7 to 13 As shown, the bushing 3 is manufactured such that its lower surface 35 extends slightly in the axial direction relative to the opening 10 of the slider 1.

[0126] In other words, the lower surface 35 extends slightly beyond the opening 10 toward the stop 22 of the guide member 2, in which case the stop also serves as a support base on the reference surface (not shown).

[0127] The extension is minimal, and in the case of overstroke, it is sufficient to make the lower surface 35 of the bushing 3 contact the guide 2, especially the upper surface 220 of the stop 22 (as shown in Figures 10 and 11).

[0128] This contact, in turn, results in a relative translation between the slider 1 and the bushing 3; in particular, it produces a movement along the X-axis direction of the bushing 3 toward the bottom wall 110 of the slider 1.

[0129] In this way, the upper edge 321 of the groove 32 moves and, due to its gradual tapering, forces the locking element 30 away from its initial seat, represented by the slot 310 (as shown in detail in Figure 12).

[0130] Therefore, due to the elasticity of the material used to manufacture the locking element 30, the locking element 30 is pushed in the same direction as the movement of the slider 1 and occupies the fifth chamber 31 in an irreversible manner.

[0131] According to a preferred embodiment, the lower surface 35 of the bushing 3 extends from the first opening 10 of the first chamber 11 to a extent at least equal to half the cross-sectional width of the locking element 30, to ensure that the locking element moves from the groove 32.

[0132] The shift is shown more clearly in the details of Figure 12, where the retraction of the locking element 30 is schematically shown by arrow F.

[0133] At this point, due to the gap established between the sliding member 1 and the bushing 3, the gasket located in the housing 40 no longer forms a complete seal with the wall 111, causing gas to escape from the chamber 11.

[0134] Therefore, the pressure loss inside one or two chambers is obtained, and the contact between the surfaces of the slider 1 and the guide 2 can be detected.

[0135] Figure 13 The image shows the gas spring 200 after the locking element 30 has changed position, releasing the bushing 3 from the slider 1.

[0136] The special shape of the housing 31 of the bushing 3, together with the elastic material used to make the locking element 30, prevents the locking element from spontaneously returning to its initial position in the slot 310.

[0137] The locking element 30 moves away from the seat 310 through the upper edge 321 of the groove 32; at the same time, the locking element 30 retracts elastically, thereby reducing its diameter.

[0138] The movement of the locking element 30 continues until it permanently occupies the housing 31.

[0139] The slider 1 is released from the bushing 3, causing the gasket to lose its seal completely, thereby releasing the gas contained in the chamber.

[0140] Therefore, gas springs can no longer be used under conditions where their integrity is at risk, and thus can be easily identified and replaced.

[0141] This avoids unintentionally prolonging the use of a damaged gas spring and / or in any near-breakage situation, preventing accidents and potentially harmful consequences that could result from such improper practice.

[0142] Figures 14A-14C illustrate another embodiment of the safety system according to the invention, which is applied to a type of gas spring that is already available on the market.

[0143] This embodiment provides a structure that is substantially the same as the one already described, but it is used in an inverted configuration.

[0144] Therefore, for ease of reading, the components of the latter embodiment are identified using the same reference numerals as previously used and have substantially the same function.

[0145] In fact, the slider 1 and the guide 2 are always restricted to reciprocating sliding, while the bushing 3 is restricted to the slider 1 and is located in the middle position between the slider and the guide 2.

[0146] The gas-containing chamber 11 is defined by a slider 1, a bushing 3, and a guide 2, which consists only of a piston equipped with a rod 120 and a head 121.

[0147] Therefore, in this simplified embodiment, the guide 2 lacks the external protection and containment wall present in other embodiments.

[0148] The airtight seal of chamber 11 is ensured by a seal (not shown) that can be inserted into chambers 40 and 130.

[0149] In addition, it may be necessary to provide an additional housing for the device used for guiding and / or cleaning rod 120.

[0150] When the compression phase exceeds the length of the gas spring's stroke, the structure and operation of the safety system based on this variant of the gas spring are essentially the same as those described so far.

[0151] As occurred in the above embodiments, in the event of undesirable contact between the external element and the guide 1 (e.g., pressure surface, etc.), the surface 35 of the bushing 3 protruding relative to the first opening 10 is pushed toward the interior of the chamber 11.

[0152] The shape of the groove 32 means that the locking element 30 (which normally prevents the bushing 3 itself from detaching from the guide 1) moves away from its seat as the bushing 3 moves on its own and can no longer maintain the locking of the two elements 1 and 2.

[0153] Therefore, as the bushing 3 shifts, the airtightness of the chamber 11 is lost, and the complete escape of gas causes the gas spring to fail.

[0154] According to preferred embodiments of the present invention, the invention is described by way of example only and without limiting the scope of application. However, it should be understood that those skilled in the art can modify and / or adjust the invention without departing from the scope of the invention.

Claims

1. A gas spring (200), comprising: Guide (2) has an outer surface (212). A slider (1), together with the guide (2), defines at least one chamber (11) containing pressurized gas. The slider (1) is slidably constrained to the guide (2) to have a minimum expansion stroke and a maximum compression stroke, during which the guide (2) is partially withdrawn from the slider (1). A bushing (3) is disposed between the slider (1) and the guide (2) and includes a sealing device for sealing the chamber (11). The bushing is detachably coupled to move integrally with the slider (1) until the maximum compression stroke, such that when the slider (1) slides relative to the guide (2) beyond the maximum compression stroke, the bushing (3) disengages from the slider (1), thereby eliminating the airtightness of the chamber (11). A safety element (230) is included to prevent the slider (1) from disengaging from the guide (2) when the slider (1) slides beyond the minimum stroke of the expansion. Its features are, The guide member (2) has a circular seat (23) corresponding to the outer surface (212), and The safety element (230) is a sig ring or stop ring, which is housed in the circular seat (23) so as to extend relative to the outer surface (212) of the guide (2).

2. The gas spring (200) according to claim 1, characterized in that, The slider (1) has a groove (32) formed on its inner side surface (111). The bushing (3) has a slot (310) arranged facing the groove (32) to form a seat, and The gas spring includes a locking element (30) housed in the seat. When the slider (1) slides relative to the guide (2) beyond the maximum stroke of the compression, the reciprocating position of the slot (310) relative to the groove (32) changes, causing the locking element (30) to leave the seat, thereby separating the bushing (3) from the slider (1) and eliminating the airtightness of the chamber (11).

3. The gas spring (200) according to claim 2, characterized in that, The groove (32) has: The first edge (320), which is close to the first opening (10) of the chamber (11) of the slider (1), and The second edge (321), which tapers gradually in the opposite direction to the first edge (320), causes the locking element (30) to move out of the seat when the bushing (3) slides relative to the slider (1), and The bushing (3) has a lower surface (35) that extends from the first opening (10) of the chamber (11) by at least half the cross-sectional width of the locking element (30) to ensure that the locking element is displaced from the groove (32), thereby disengaging the bushing and eliminating the seal of the chamber (11).

4. The gas spring (200) according to claim 1, characterized in that, The safety element (230) is configured to extend from the outer surface (212) of the guide (2).

5. The gas spring (200) according to claim 1, characterized in that, The guide (2) has a second opening (20), and The safety element (230) is arranged on the outer surface (212) of the guide (2) and corresponds to the second opening (20).

6. The gas spring (200) according to claim 1, characterized in that, The bushing (3) includes a lip (132) on its inner surface (311) that is designed to interfere with the safety element (230) when the slider (1) reaches the minimum stroke.

7. The gas spring (200) according to claim 5, characterized in that, The gas spring includes: End stop (12), comprising: Rod (120), which is integral with the slider (1) and constrained to slide through the second opening (20) of the guide (2), and The head (121) is inserted into the guide (2) and configured to abut against the step (124) defined by the second opening (20), thereby preventing separation between the slider (1) and the guide (2).

8. The gas spring (200) according to any one of the preceding claims, characterized in that, The gas spring includes: Device for sealing the chamber (11), located between the bushing (3) and the slider (1); and guide device for reciprocating sliding of the guide (2) and the bushing (3), located between the bushing (3) and the guide (2).

Images