GAS SPRING

Abstract

The present invention relates to a gas spring comprising a first element, a second element, and a limit, wherein the second element comprises a first chamber and a first opening for accessing the first chamber, the first element is fixable to a reference plane and comprises a second chamber), a second opening for accessing the second chamber, and external walls, and is inserted into the first chamber through the first opening, wherein said first and second elements are movable and reciprocally slide along an axis, wherein the limit comprises a stem and a head adapted to slide through the second opening into the second chamber parallel to the axis so as to limit the maximum travel of the second element to the extension of the external walls of the first element, wherein said first and second chambers communicate through an existing play between said stem and said second opening, and the second element slides through the first opening along the external walls of the first element.

Claims

1. Gas spring comprising: a first element, a second element, and a limit, wherein the second element comprises: a first chamber, a first opening for accessing the first chamber, and a first internal surface, the first element is fixable to a reference plane and comprises: a second chamber, a second opening for accessing the second chamber, and external walls, and is inserted into the first chamber of the first element through the first opening, wherein said first and second elements are movable and reciprocally slide along an axis, wherein the limit comprises: a stem and a head adapted to slide through the second opening into the second chamber parallel to the axis so as to limit the maximum travel of the second element to the extension of the external walls of the first element, and wherein said first and second chambers communicate through an existing play between said stem and said second opening, and the second element slides through the first opening along the external walls of the first element.

2. (canceled)

3. Gas spring according to claim 1, further comprising a first loading valve for loading a gas into the spring, placed in a second internal surface of the first element.

4. Gas spring according to claim 1, wherein the limit is integral with the second element.

5. Gas spring according to claim 1, further comprising a first guide configured to guide the limit, placed between the stem of the limit and the second opening of the first element, and a second guide configured to guide the second element, placed at the first opening.

6. Gas spring according to claim 1, wherein the second element comprises a second loading valve.

7. Gas spring according to claim 6, wherein the second element comprises channels for connecting the second loading valve with the first chamber.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0046] The present invention is now described, by way of example and without limiting the scope of the invention, with reference to the accompanying drawings which illustrate preferred embodiments of it, wherein:

[0047] FIG. 1 is a sectional view of a first embodiment of the gas spring according to the invention;

[0048] FIG. 2 is a schematic cross-section view of the gas spring in FIG. 1;

[0049] FIG. 3 shows a sectional view of a second embodiment of the gas spring according to the invention;

[0050] FIG. 4 shows a sectional view of a third embodiment of the gas spring according to the invention;

[0051] FIGS. 5A and 5B included in FIG. 5 show gas springs belonging to the known technique.

DETAILED DESCRIPTION

[0052] With reference to FIGS. 1 and 2, the gas spring according to the invention, generically indicated with 100, comprises a hollow sliding element 1, provided with a first opening 14 that faces a first chamber 11, inside which a guide 2 is positioned, it also hollow; the first seals or sealing means 5 are placed on the internal surface 12 of the sliding element 1, facing the external surface 22 of the guide 2.

[0053] A piston 3 is placed in the first chamber 11 of the sliding element 1, acting as limit, in order to prevent the sliding element 1-guide 2 system from slipping out; this piston 3 is provided with a head 31 and a stem 32; the latter is integral with a first wall 13 of the first chamber 11 in the position opposite to the first opening 14.

[0054] The guide 2 serves as a constraint for the sliding of the stem 32 through a second opening 23, oriented towards the chamber 11, obtained at the top of the guide 2.

[0055] The head 31 is instead constrained to slide in a second chamber 21 of the guide 2, and its diameter is greater than that of the stem 32; operatively, therefore, once the guide 2 is inserted into the sliding element 1, piston 3 is inserted into and fixed to the first wall 13.

[0056] In any case, the first opening 14 has dimensions substantially corresponding to the first wall 13 so that the sliding element 1 is without a base and the seals 5 between the external walls 22 of the guide and the slider 1 itself are directly on the internal wall 12 of the latter.

[0057] In other words, the first opening 14 is made in such a way that the slider 1 is completely bottomless; bottomless here means that the vertical walls 12 do not have any element projecting therefrom (apart from any seals or guiding means).

[0058] This advantageously results in a spring with a highly space-saving configuration that is smooth in operation and eliminates many of the drawbacks of the known technique.

[0059] First of all, the fact that one element is placed above the other and slides on its external surface at the same time allows simplifying the design of the spring and increasing its durability and safety.

[0060] In fact, a spring thus designed is easy to build and assemble as it eliminates the complicated sealing interactions between the seals usually fixed to the external wall of the piston and the internal wall of the chamber.

[0061] In addition, the position and sliding mode of the upper element (in this case slider 1) on the external surface of the other element (the guide 2) creates protection against contaminants entering the chamber which is integrated with the spring, and is much more efficient and easier to implement than other solutions adopted in the known technique.

[0062] In further embodiments, the function of the head 31 can be performed by different elements, such as profiles and/or edges obtained on the surface of the stem 32 and/or chamber 21, which can in any case prevent the stem 32 from completely coming out of chamber 21 during the expansion of the gas spring.

[0063] In this way, the sliding element 1 is constrained to move along the axis X of the guide 2 in relation to the latter.

[0064] In the case of the embodiments shown in the drawings, which provide the presence of the piston 3, the travel is determined by the distance between the first abutments 210 of the chamber 21, in particular provided in the upper surface of the guide 2, and the head 31 of the piston 3, or between a second wall 211, opposite to such first abutments 210 and the head 31 itself.

[0065] In other words, the excursion of the head 31 in the chamber 21 between the wall 211 and the abutments 210 can determine the travel of the sliding element 1 along the external surface 22 of the guide 2.

[0066] In alternative embodiments, wherein the piston 3 is absent, or in which its extension is in any case less than that of the guide 2 along the axis X (FIG. 4), the wall 13 of the sliding element can act as the lower limit, stopping its travel at the abutments 210 of the upper surface of the guide 2.

[0067] Moreover, there is inserted, on wall 211, a loading valve 6 for injecting the gas into the chambers 21 and 11, held in position by a locking ring 51.

[0068] There may be second seals or sealing means 53 on the sealing surfaces of valve 6 inside the chamber 21.

[0069] The total volume available to the gas therefore, is formed by both chambers 11 and 21, which are placed in communication by the existing play between the stem 32 of the piston 3 and the second opening 23.

[0070] The operation of the gas spring 100 is based on the reciprocal sliding between the sliding element 1 and the guide 2, and between the stem 32 and the second opening 23; FIG. 2 shows, in a schematic way to increase its intelligibility, the surfaces on which the gas pressure contained in chambers 11 and 21 exerts its force.

[0071] Specifically, these surfaces are: [0072] a first surface 10, belonging to the sliding element 1, on which the gas exerts a positive force (indicated by the + references); the area on which the gas pressure exerts a force is equal to the internal area of sliding element 1 itself minus the area of the stem 32; [0073] a second surface 20, belonging to the head 31 of piston 3, facing in the same direction as the first surface 10, on which the gas exerts an equally positive force; the area available to the gas is equal to the area of the top of the piston 3; [0074] a third surface 30, it also belonging to the head 31 but facing in the opposite direction to the surfaces 10 and 20; consequently, the contribution given by the force exerted on it by the gas (indicated by the references −) will have the opposite direction to the first two contributions, and will be calculated on the area of the top of the piston 3 minus the area of the stem 32.

[0075] The sum of the contributions of the three surfaces 10, 20 and 30 therefore, will be equivalent to a force exerted by the gas on an area equal to the internal area of the sliding element 1; this advantageously allows obtaining load values comparable to those bearable by a gas spring of the jacket seal type.

[0076] In addition, a solution designed in this way also makes it possible to take advantage of the advantages of the stem seal configuration; in fact, since the internal wall 12 of the sliding element 1 and the external wall 22 of the guide 2 are the only sliding surfaces, it is possible to couple them in the same convenient way used in the stem seal variant, which provides, as mentioned above, the use of seals 5 at the interface between the two.

[0077] In the “jacket seal” springs of the known technique, the sealing means are housed on the side surface of a piston, which looks like a relatively small element that slides on the internal walls of a chamber.

[0078] Moreover, once compressed, the piston always has one face facing the inside of the chamber and one facing the intermediate vacuum environment. In the spring according to this invention, the reduced surface area of the piston is replaced by the larger surface area of the guide 2, facilitating reciprocal sliding and minimizing the probability of breakdowns or malfunction.

[0079] In addition, in the gas spring according to the invention, the interface at the sealing means is exposed at all times to the pressure of the chamber on the one hand and the pressure of the external environment on the other.

[0080] The total pressure difference at the interface therefore, is smaller, and this ensures a better seal, greater safety and also allows reducing the size of the seals to be installed.

[0081] The sliding element 1, sliding outside the guide 2, protects the sliding surface, which is represented by the external surface 22 of the guide 2 in the embodiment described.

[0082] In this way, the depression phenomenon typical of jacket springs is eliminated and the possibility of particles and/or undesired substances creeping into chambers 11 and 21 is minimized.

[0083] Moreover, this solution makes it possible to carry out mechanical surface finish machining on the external surface 22 of the guide 2 in a simpler way than the machining of the internal walls, and with the possibility of obtaining higher degrees of finish.

[0084] A gas spring of the type described has the additional advantage of also exploiting the external surface of the cylinder to increase the seal of the chamber; consequently, the average working pressure and the relative developed temperature are lower with respect to known springs, developed force being equal.

[0085] This, on the one hand, increases safety during spring operation and, on the other hand, allows for more compact springs.

[0086] In addition, the guide 2 may have a larger base 25 than the external surface 22 to act as the second limit of the slider 1 in order to further protect the gap between the external surface 22 of the guide 2 and the internal surface 12 of slider 1 itself. In fact, in this way the sliding of the slider is interrupted at a certain distance from the support surface (equal to the height of the base of the guide) and, even in the presence of any oil or other elements on the surface, their entry into the gap is made less immediate.

[0087] Operationally, the gas is loaded into the chamber 11 via a first loading valve 6 and/or a second loading valve 61.

[0088] The second valve 61 is placed along a wall of the chamber 11 adjacent to the external environment.

[0089] In the variant shown, the second loading valve 61 is placed in the wall 13; in order to allow the gas to reach the chamber 11, channels 62 are obtained inside the wall 13 itself so as to bypass the overall volume of the stem 32, which is also fixed to the wall 13.

[0090] In addition, the second opening 23 may have guiding means 24 to improve the sliding of the stem 32 through it, (FIG. 3); similarly, the first opening 14 may also have guiding means 205 for the sliding of the sliding element 1 on the guide 2; in this case, it is possible to obtain two distinct sliding control positions of the sliding element 1 along the axis of the guide 2, avoiding the dangerous jamming phenomenon between the sliding element 1 and the guide 2 itself due to an offset between the two elements. Contrarily indeed, the spring would get jammed, subsequently causing a dangerous uncontrolled release of the sliding element due to the increase in gas pressure inside the chamber.

[0091] The fact that this variant of the spring has two communicating chambers 11 and 21 contributes to the aforementioned objective of achieving greater efficiency and durability, spring size being equal. In fact, also thanks to this contrivance it is possible to decrease the internal pressure since it is distributed on the walls of both chambers, unlike the known technique that provides for the various compartments to remain watertight, and therefore they must withstand greater stress.

[0092] Likewise, with reference to FIG. 1, it is also possible to add guiding means 105, in particular a stem guide, to the seals 5 on the internal wall 12 of the slider 1.

[0093] In addition, it is possible to drill holes in the abutments 210 so as to ensure communication between the chamber 21 of the guide 2 and the chamber 11 of the slider.

[0094] These measures, together with the distribution of the force over a larger area, which consequently significantly reduces the pressure inside the spring, are particularly advantageous from a safety point of view, minimizing the risk of accidents.

[0095] FIG. 4 shows a second variant of the invention. In general, the gas spring 300 has substantially the same elements mentioned so far for the previous embodiments, which are in fact indicated by the same numerical references.

[0096] In detail, however, the seal 5 and the stem guide 305 are further protected against oil or dust infiltration by being completely recessed in the internal walls 12 of the chamber 11 of the slider 1.

[0097] This allows the cylinder surface to be exploited to the maximum, while having a lower protection 301 for the seals 5 and stem guide 305 comprising the thickness of the wall 12 itself.

[0098] The sliding element 1 is constrained to slide along the axis X between a first end, comprising the wall 13 of slider 1 itself, and a second end comprising the head 31 of the piston 3, both constrained by the abutments 210 of the upper wall of the guide 2.

[0099] The base 25 in this case is wider than the external walls 22 of the guide, but narrower than the overall dimensions of the sliding element 1 so that the lower protection 301, consisting essentially of the lower end of the wall 12, overhangs slightly from the base 25 itself.

[0100] The base 25 is also completely open at the bottom so as to accommodate a closing element 326 adapted to fit into the base 25 itself once the piston 3 has been inserted into the chamber 21.

[0101] In detail, in fact in this case the piston 3 is made in a single piece; moreover, the piston 3 has a cavity 33 that develops along the axis X.

[0102] The same technical solution just described that concerns the closing element 326 can be implemented on the wall 13 of the first chamber 11, for example in the embodiment in FIG. 3.

[0103] In this way, the gas spring becomes almost completely symmetrical in the arrangement of its parts, to the advantage of the construction simplicity and assembly of the parts.

[0104] The invention is described by way of example only, without limiting the scope of application, according to its preferred embodiments, but it shall be understood that the invention may be modified and/or adapted by experts in the field without thereby departing from the scope of the inventive concept.