Dispenser for dispensing a fluid

Abstract

Described is a dispenser (1) for dispensing a fluid, made of recyclable plastic material, comprising a containment body (2), a suction pipe (3), a ring nut (9), a piston (6), a hollow stem (5), a dosing chamber (10), a tip (7), a dispensing head (13), a retaining ring (14) and a no-load pneumatic spring. The no-load pneumatic empty being positioned in an annular chamber with a variable volume defined by the piston (6), by the retaining ring (14), by the hollow stem (5) and by an upper stretch (16) of the containment body (2). The no-load pneumatic spring being configured to move axially upwards the slidable parts connected to the dispensing head (13), to return them to a rest condition, after the dispenser (1) has been actuated by a user by means of it.

Description

DescriptionTitle of Invention: DISPENSER FOR DISPENSING A FLUID

[0001] This invention relates to a dispenser for dispensing a fluid, that is to say, a dispensing device applicable to the neck of a bottle in order to dispense the fluid contained in the bottle.

[0002] As is known, a dispenser is commonly used for dispensing liquid, such as, for example soap (or other products not explicitly mentioned below).

[0003] The liquid is contained in a bottle with which the dispenser is associated by means of suitable connecting means.

[0004] These dispensers for dispensing fluid are located in the market for single-use products, where the attention for these products is increasingly oriented towards sustainable solutions with a low environmental impact.

[0005] In particular, a requirement for products in the so-called packaging sector, to which the dispensers for dispensing fluid form part, is to limit the variety of raw materials used, possibly with a view to solutions consisting of a single type of material or, alternatively, materials belonging to the same family.

[0006] In order to meet this market need, there are dispensers made entirely of plastic, in such a way as to allow an easy disposal and possible subsequent recycling of the entire packaging, that is to say, of the bottle-dispenser assembly.

[0007] Currently, in order to achieve said aim, in these dispensers made entirely of plastic it has been necessary to replace the metal spring commonly used, with a return element provided with the same functional and dimensional features.

[0008] The dispenser according to this invention falls into a field already rich in solutions which, however, in the majority of cases, see the use of elastic components made of plastic.

[0009] Disadvantageously, these components made of plastic material do not guarantee the same performance levels as the corresponding metal elements.

[0010] The components made of plastic material, currently used, are quite slow to return to the rest position, due to hysteresis phenomena, and are also sensitive to relaxation under tension. Disadvantageously, they therefore require an over-sizing of the workloads, which makes the dispenser more inconvenient for the end user, due to the greater force necessary for the actuation.

[0011] Amongst the solutions identified in the prior art, although not yet on the market, there are also dispensers which comprise an elastic return system based on a “vacuum chamber”. These systems have the advantage of providing a good capacity for suction of the product, at the same time being very comfortable to use, with a limited actuation force, which does not increase in the final part of the actuation stroke.

[0012] Disadvantageously, these solutions require a high constructional complexity and / or very precise and expensive components, in order to guarantee a good efficiency of the vacuum system and especially to maintain the relative efficiency over time and / or after numerous actuations of the dispenser.

[0013] The technical purpose of the invention is therefore to provide a dispenser for dispensing a fluid which is able to overcome the drawbacks of the prior art.

[0014] The aim of the invention is therefore to provide a dispenser for dispensing a fluid made entirely with materials which are easy to dispose of and then recyclable with the entire packaging.

[0015] A further aim of this solution is to provide a dispenser for dispensing a fluid which guarantees a good suction capacity with a limited actuation force.

[0016] A further aim of the invention is to provide a dispenser for dispensing a fluid which retains full efficiency during the entire life of the product, maintaining unaltered the performance levels of the dispenser.

[0017] A further aim of the invention is to provide a dispenser for dispensing a fluid which is able to maintain low production costs, adopting technical solutions which allow simple and fast assembly processes with obvious advantages in terms of hourly productivity and the energy needed for producing the dispenser.

[0018] Lastly, a further aim of the invention is to provide a dispenser for dispensing a fluid which retains all the functional and performance features of traditional dispensers with a metal spring, both in relation to the protection and the safeguarding of the integrity of the package and the relative contents, and with regard to the effectiveness and comfort of use.

[0019] The technical purpose indicated and the aims specified are substantially achieved by a dispenser for dispensing a fluid comprising the technical features described in one or more of the appended claims. The dependent claims can correspond to possible embodiments of the invention.

[0020] The invention describes a dispenser for dispensing a fluid comprising a containment body, a suction pipe, a ring nut, a piston, a hollow stem, a dosing chamber, a tip, a dispensing head, a retaining ring and a no-load pneumatic spring.

[0021] The dispenser is made of recyclable plastic material.

[0022] The hollow containment body can be inserted in a bottle and comprises at the bottom an orifice for sucking fluid from the bottle and a ball inlet valve.

[0023] The suction pipe is connected to the bottom of the containment body.

[0024] The ring nut is connected or connectable to the neck of the bottle associated with the containment body.

[0025] The piston is slidable inside the containment body between a raised position and a lowered position.

[0026] The hollow stem, which is axially slidable inside the containment body, has a flange defining an upper portion associated with the dispensing head and at the bottom a shoulder provided with grooves.

[0027] The dosing chamber is defined in a central portion of the containment body.

[0028] The tip is coupled to the lower end of the hollow stem by means of a system of undercuts, for locking a sliding movement of the piston connected to them, and is also provided with a conical surface from which a base flange extends.

[0029] The slidable movement of the piston determines the opening of a passage opening, allowing the transfer of the product to be dispensed present inside the dosing chamber towards the inner cavity of the hollow stem.

[0030] The dispensing head comprises a central portion connected to an upper portion of the hollow stem for controlling the actuation of the piston and a spout designed to dispense the fluid contained in the bottle.

[0031] The dispensing head can be pressed by a user between a raised position and a lowered position.

[0032] The retaining ring is integral with the containment body and inserted in it for housing and guiding the hollow stem in the relative stroke inside the containment body.

[0033] The no-load pneumatic spring is positioned in an annular chamber with a variable volume defined by the piston, by the retaining ring, by the hollow stem and by an upper stretch of the containment body.

[0034] The no-load pneumatic spring is configured to move axially upwards, the mobile unit consisting of hollow stem, tip, piston and dispensing head, returning it to a nonoperating rest condition.

[0035] Further features and advantages of the invention are more apparent in the nonlimiting description which follows of a preferred non-exclusive embodiment of a dispenser for dispensing a fluid.

[0036] The description is set out below with reference to the accompanying drawings which are provided solely for purposes of illustration without restricting the scope of the invention and in which:

[0037] - Figure 1 is a view of a longitudinal cross section of a possible embodiment of the dispenser according to this invention;

[0038] - Figures 2 to 5 are schematic views of some components which may be present in the dispenser according to the invention;

[0039] - Figures 4A and 5A are cross section views of the respective components shown inFigures 4 and 5.

[0040] With reference to the accompanying drawings, the numeral 1 denotes in its entirety a dispenser for dispensing a fluid which, for simplicity of description, will be referred to hereafter as the dispenser 1.

[0041] The dispenser 1 is made of recyclable plastic material.

[0042] The dispenser 1 according to the invention is an alternative volumetric pump consisting of a hollow cylindrical containment body 2 which can be inserted in a bottle comprising at the bottom an orifice for sucking fluid from the bottle and a ball inlet valve 4, a ring nut 9 associated with the containment body 2 and provided with a thread or undercut for coupling or any type of solution for connecting to a bottle, and a suction pipe 3, coupled in the lower part of the containment body 2, for sucking the product from the bottle.

[0043] The containment body 2 has at the bottom a tubular protrusion for coupling the suction pipe 3 and a housing for the ball, which acts as an inlet valve 4, with retention protrusions 15 which have the function of retaining the ball inlet valve 4 in its area of operation. The ball inlet valve 4 raises allowing the inlet of the liquid and returns to the sealing position preventing the opposite flow.

[0044] The dispenser 1 comprises, above the ball inlet valve 4, a dosing chamber 10 defined in a central portion 2c of the containment body 2 and limited by an upper stretch 16 of the containment body 2.

[0045] According to a possible embodiment, the containment body 2 has a compensation hole 34 configured to define an air compensation path.

[0046] The dispenser 1 also comprises a sliding piston 6 which limits at the top the dosing chamber 10.

[0047] The piston 6 is slidable inside the containment body 2 between a raised position and a lowered position.

[0048] The piston 6 is coupled to a hollow stem 5, on which it can slide only to a limited extent, locked at the bottom by a tip 7, which is in turn attached at the bottom to the hollow stem 5 by means of a system of undercuts.

[0049] More specifically, the dispenser 1 comprises a hollow stem 5 axially slidable inside the containment body 2 and having a flange 21 which delimits an upper portion of it, and at the bottom a shoulder 22 provided with grooves 37.

[0050] The tip 7 is located below the hollow stem 5, and is provided with a system of undercuts and also a conical surface 24 and a base flange 25 which is sufficiently large to ensure a stable positioning during the assembly.

[0051] The tip 7 is configured for transferring through a relative cavity 23 the product to be dispensed present inside the dosing chamber 10.

[0052] The sliding of the piston 6 on the hollow stem 5 allows the cavity 23 of the tip 7 to be opened, thus creating a delivery valve which opens when the piston 6 and the hollow stem 5 slide downwards (reducing the volume of the dosing chamber 10 and compressing the liquid) and closes during the upstroke (expanding the volume of the dosing chamber 10).

[0053] More in detail, during the dosing stroke, the hollow stem 5 moves downwards relative to the piston 6 opening the cavity 23 of the tip 7 and putting in fluid communication the dosing chamber 10 and the inner channel of the hollow stem 5, whilst during the suction stroke, upwards, the piston 6 moves down closing the cavity 23 of the tip 7 and preventing the liquid from flowing backwards.

[0054] The piston 6 is substantially annular in shape with an inner cylindrical portion which is positioned around the hollow stem 5 and the tip 7, an outer circumferential lip which seals against the inner walls of the containment body 2, and a flange which connects the inner cylindrical portion with the outer circumferential lip.

[0055] Lastly, the piston 6 comprises a shoulder which performs the dual function of sealing the top of the tip 7 during the suction and limiting the stroke of the piston 6 relative to the hollow stem 5, during the actuation.

[0056] The hollow stem 5 is connected at the top to a dispensing head 13 by means of a system of undercuts 20 provided with anti-rotation ribs.

[0057] The dispensing head 13 of the dispenser 1 comprises a central portion connected to an upper portion of the hollow stem 5 for controlling the actuation of the piston 6.

[0058] The dispensing head 13 also comprises a spout designed to dispense the fluid contained in the bottle.

[0059] The dispensing head 13 can be pressed by a user between a raised position and a lowered position.

[0060] The dispenser 1 also comprises a retaining ring 14 integral with the containment body 2 and inserted therein for housing and guiding the hollow stem 5 in the relative stroke inside the containment body 2.

[0061] The retaining ring 14, coupled inside the containment body 2 through a system of undercuts 31 and suitable anti-rotation ribs 18 present on the containment body 2, closes the top of the containment body 2, leaving a passage hole through which the hollow stem 5 slides.

[0062] Above the seat in which the retaining ring 14 engages, the containment body 2 has a flange 19 which rests on the neck of the bottle by means of a sealing gasket 8, and to which the ring nut 9 is coupled.

[0063] According to a possible embodiment, the retaining ring 14 defines a non-operating closed or stop position, wherein the dispensing head 13 of the dispenser cannot be actuated, and an operating position wherein the dispensing head 13, and with it all the slidable elements, can move from a raised position to a lowered end of stroke position.

[0064] The raised position is defined at a height lower than the closed or stop position.

[0065] The retaining ring 14 is provided with extensions in the shape of an arc 32 which, together with ribs positioned on the dispensing head 13, form the stop system.

[0066] More specifically, the arc-shaped extensions 32 of the retaining ring 14 comprise an upper surface 33 defined by an inlet slide, a stop tooth and a groove limited by a final shoulder.

[0067] During the stopping, that is to say, after the 90° rotation of the dispensing head 13, the rib of the dispensing head 13 is drawn upwards by the inlet slide, passes beyond the tooth and is positioned in the groove.

[0068] The presence of the inlet slide allows the closed position, or stop position, to be at a height greater than the raised position, for reasons which are described below.

[0069] The tooth, on the other hand, to be exceeded, allows the opening torque to be increased and prevents accidental openings of the dispenser 1.

[0070] The dispenser 1 also comprises an no-load pneumatic spring, positioned in an annular chamber with a variable volume defined by the piston 6, by the retaining ring 14, by the hollow stem 5 and by an upper stretch 16 of the containment body 2.

[0071] The no-load pneumatic spring is configured to move axially upwards the mobile unit, that is to say, the hollow stem 5, and integrally with it, the tip 7, the piston 6 and the dispensing head 13, until reaching the raised position.

[0072] In other words, the slidable components of the dispenser 1, which during the lowering stroke dispense the liquid, are returned to the “high” rest position thanks to a no-load pneumatic spring, made using a system of components located inside the containment body 2, in the annular space delimited by the piston 6, by the retaining ring 14, by the hollow stem 5 and by the upper stretch 16 of the wall of the containment body 2.

[0073] According to a possible embodiment, the no-load pneumatic spring comprises a fixed upper seal 11 and a lower seal 12 slidable inside the annular chamber.

[0074] The upper seal 11 comprises, preferably, a cylindrical central portion 26.

[0075] The cylindrical central portion 26 of the upper seal 11 has at the bottom a circumferential widening 27 from which extends in height an outer cylindrical wall 39, and at the top an outer lip 28 and an inner lip 29.

[0076] The outer lip 28, in sealing contact against an inner circumferential skirt 38 of the retaining ring 14, acts as a one-way valve to allow the entry into the bottle of outside air (so-called compensation air), coming from the passage opening present between the hollow stem 5 and the retaining ring 14, to compensate for the reduction in the volume of liquid gradually discharged from the bottle.

[0077] The inner lip 29 is, on the other hand, configured for sealing the no-load pneumatic spring, making contact against the cylindrical surface of the hollow stem 5, with a larger diameter such as to guarantee interference with the inner lip 29.

[0078] According to a possible embodiment, the containment body 2 comprises a conical stretch 17 defined for compressing the circumferential widening 27 of the upper seal 11, guaranteeing the sealing of the upper part of the no-load pneumatic spring.

[0079] The upper seal 11 is located, preferably, under the retaining ring 14, and is substantially fixed between the latter and the containment body 2.

[0080] The upper seal 11 can comprise a plurality of axial slots 30, made in the outer cylindrical wall 39, configured to complete the path of the compensation air, penetrated through the outer lip 28, allowing the passage towards a circumferential gap delimited between the upper seal 11 and the containment body 2, and connected to the hole 34 of the containment body 2.

[0081] More in detail, the compensation air, which restores the volume of product dispensed, passes through a gap present between the hollow stem 5 and the retaining ring 14, reaching the outer upper lip 28 of the upper seal 11 in sealing contact with the circumferential inner skirt 38 of the retaining ring 14.

[0082] During the return stroke, the compensation air passes through the sealing contact made by the outer upper lip 28 of the upper seal 11 against the circumferential inner skirt 38 of the retaining ring 14, thanks to the negative pressure generated inside the bottle and the thrust towards the outside transmitted on the upper seal 11 from the zone of the hollow stem 5 with a larger diameter, which favour the detachment of the sealing contact surfaces.

[0083] The compensation path is then completed through the axial slots 30 of the upper seal 11, the circumferential gap made between the upper seal 11 and the containment body 2, and lastly through the compensation hole 34 of the containment body 2.

[0084] The lower seal 12, on the other hand, may be made in the form of an annular element provided with an outer protrusion 35 having two undercuts, designed for forming a seal with the containment body 2.

[0085] The lower seal 12 may also be made in the form of an annular element provided with an inner protrusion 36 having two undercuts.

[0086] The inner protrusion 36 is configured for making a seal with the hollow stem 5.

[0087] Preferably, the lower seal 12 comprises both the outer protrusion 35 and the inner protrusion 36.

[0088] The lower seal 12 defines a rest configuration resting on the upper seal 11, coinciding with the raised position of the sliding elements of the dispenser 1.

[0089] Moreover, in a use configuration, the inner protrusion of the lower seal 12 rests at the top on the shoulder 22 of the hollow stem 5 to allow the movement downwards of the lower seal 12 under the pushing action of the hollow stem 5 during the step of actuating the dispenser 1, and the opposite movement, upwards, of the hollow stem 5,pushed by the lower seal 12, during the raising step which returns the dispenser 1 to the rest position.

[0090] According to a possible embodiment, the annular chamber with a variable volume, or vacuum chamber, which forms the pneumatic spring, is delimited by the hollow stem 5, the containment body 2 and by the lower 12 and upper 11 seals just described.

[0091] As mentioned, the closed position, or stop position, is higher than the raised position.

[0092] The difference in height between the raising position and the stop position, defined by the retaining ring 14, determines the opening / closing of a passage of fluid communication between the vacuum chamber and the outside environment to allow the restoring of an optimum pressure condition of the no-load pneumatic spring.

[0093] The difference in height between the raised position and the stop position determines the opening of a path for discharging air for the no-load pneumatic spring.

[0094] The shoulder 22 of the hollow stem 5 is configured for making contact, in the stop position, with the inner lip 29 of the upper seal 11 defining a path for discharging air for the no-load pneumatic spring through the grooves 37 of the shoulder 22.

[0095] More in detail, in the highest stop position, the shoulder 22 of the hollow stem 5 is in contact with the inner lip 29 of the upper seal 11 defining a passage path thanks to the grooves 37 present on it, whilst in the raised or rest position, the inner lip 29 of the upper seal 11 is in contact with the full cylindrical portion of the hollow stem 5.

[0096] Still more in detail, the operational dynamics of the pneumatic spring are described below during the three positions of the dispenser 1.

[0097] In the stop position, that is to say, the highest position of the hollow stem 5 relative to the fixed components (retaining ring 14 and upper seal 11), the lower seal 12 is in contact with the upper seal 11 and the volume of the vacuum chamber which forms the pneumatic spring is at its minimum.

[0098] In this condition, the vacuum chamber is in contact with the outside environment by means of the grooves 37 present on the shoulder 22 of the hollow stem 5, whilst the dosing chamber 10 is closed.

[0099] In the first stretch of the actuating stroke, the hollow stem 5, moved by the user through the dispensing head 13, can slide inside the fixed components, and also relative to the lower seal 12 and to the piston 6, which are retained thanks to the friction of their outer lips against the inner walls of the containment body 2.

[0100] The initial sliding of the hollow stem 5 is such that the upper cylindrical part of the hollow stem 5, with the larger diameter, makes contact with the inner lip 29 of the upper seal 11, forming a complete seal.

[0101] The shoulder 22 of the hollow stem 5 comes into contact with the upper part of the inner protrusion of the lower seal 12, to allow the subsequent pulling of it.

[0102] The delivery valve, formed by the sliding system hollow stem 5 and the piston 6, is opened and the lower edge of the hollow stem 5 comes into contact with the lower flange, facing the inside, of the piston 6, to allow the subsequent pulling which determines the dispensing of the product.

[0103] In those conditions the dosing chamber 10 is open, allowing the dispensing of the liquid, whilst the variable- volume vacuum chamber, which forms the pneumatic spring, is sealed.

[0104] In the subsequent part of the downwards stroke, the vacuum chamber, now sealed by the sliding seal formed between the hollow stem 5 and the inner lip 29 of the upper seal 11, expands due to the sliding downwards of the lower seal 12, generating an internal negative pressure which tends to zero and a consequent recalling force which opposes the motion.

[0105] During this step, the dosing chamber 10 is compressed, dispensing the product.

[0106] At the end of stroke the volume of the vacuum chamber is at its maximum and its internal pressure is kept close to zero.

[0107] When the pressing action of the user is removed, when the user stops applying the force on the dispensing head 13, the force generated by the pressure difference draws the lower seal 12 upwards.

[0108] Simultaneously, due to the friction of the piston 6 with the containment body 2, the piston 6 lowers closing the outlet valve and allowing the suction of the liquid.

[0109] The lower seal 12 returns upwards pushing up the hollow stem 5 by the shoulder 22.

[0110] The mobile unit continues the raising motion to the high position, until the lower seal 12 returns into contact with the upper seal 11 ending its raising stroke.

[0111] In these conditions the volume of the vacuum chamber returns to the minimum and the raising motion stops.

[0112] During this step, the annular chamber is still closed by the sliding contact between the inner lip 29 of the upper seal 11 and the smooth surface with a greater diameter of the hollow stem 5.

[0113] When the dispenser 1 is returned to the stop position the slide on the upper surface 33 of the retaining ring 14 further lifts the hollow stem 5.

[0114] Simultaneously, the shoulder 22 of the hollow stem 5 detaches from the lower seal 12 which cannot continue its motion since it is in contact with the upper seal 11.

[0115] The hollow stem 5 also slides relative to the upper seal 11 until the inner lip 29 of the latter is on the grooved stretch of the hollow stem 5.

[0116] Consequently, advantageously, the volume of the vacuum chamber is placed in communication with the outside environment allowing any air to be discharged which may have entered during operation through imperfections of the sliding seals.

[0117] The piston 6 is also pulled upwards by the tip 7, integral with the hollow stem 5, and comes into contact with the lower seal 12, thus guaranteeing the sealing of the dosing chamber 10.

[0118] The discharge of the air allows the no-load pneumatic spring to be returned to the initial and optimum operating conditions in such a way as to be fully efficient in the subsequent actuations.

[0119] Advantageously, the dispenser 1 is able to overcome the drawbacks of the prior art.

[0120] Advantageously, the invention provides a dispenser 1 made entirely from materials which are easy to dispose of and then recyclable with the entire packaging.

[0121] Advantageously, this invention guarantees a good suction capacity with a limited actuation force, avoiding the drawbacks of the plastic springs.

[0122] Advantageously, the invention maintains full efficiency during the entire life of the product, keeping unchanged the performance levels of the dispenser 1.

[0123] Advantageously, this invention is able to keep production costs low, adopting technical solutions which allow simple and fast assembly processes with obvious advantages in terms of hourly productivity and the energy needed for producing the dispenser 1.

[0124] Advantageously, the dispenser 1 for dispensing a fluid retains all the functional and performance features of the traditional dispensers with a metal spring, both in relation to the protection and the safeguarding of the integrity of the package and the relative contents, and as regards the effectiveness and comfort of use.

Claims

Claims

1. A dispenser (1) for dispensing a fluid, made of recyclable plastic material, comprising:- a hollow containment body (2) which can be inserted in a bottle and comprising at the bottom an orifice for sucking fluid from said bottle and a ball inlet valve (4);- a suction pipe (3) connected at the bottom to said containment body (2);- a ring nut (9) connected or connectable to the neck of said bottle associated with said containment body (2);- a piston (6) slidable inside said containment body (2) between a raised position and a lowered position;- a hollow stem (5) axially slidable inside said containment body (2) and having a flange (21) delimiting an upper portion of said hollow stem (5), and at the bottom a shoulder (22) provided with grooves (37);- a dosing chamber (10) defined in a central portion (2c) of said containment body (2);- a tip (7) connected at the bottom to said hollow stem(5) by means of a system of undercuts and defining a conical surface (24) and a base flange (25), configured for transferring through a relative cavity (23) the product to be dispensed present inside said dosing chamber (10);- a dispensing head (13) comprising a central portion connected to an upper portion of said hollow stem (5) to actuate said piston (6) and a spout designed to dispense said fluid contained in said bottle, when said dispensing head (13) is pressed by a user between a raised position and a lowered position;- a retaining ring (14) integral with said containment body (2) and inserted therein for housing and guiding said hollow stem (5) in the relative stroke inside the containment body (2); characterised in thatit comprises a no-load pneumatic spring, positioned in an annular chamber with a variable volume defined by said piston (6), said retaining ring (14), said hollow stem(5) and by an upper section (16) of said containment body (2), configured for axially moving upwards, said hollow stem (5) and, integral with it, said tip (7), said piston (6) and said dispensing head (13), until reaching said raised position.

2. The dispenser (1) according to claim 1, wherein said no-load pneumatic spring comprises a fixed upper seal (11) and a lower seal (12) slidable in said annular chamber.

3. The dispenser (1) according to claim 2, wherein said upper seal(11) comprises a cylindrical wall (26) having at the bottom a circumferential widening (27) and at the top:- an outer lip (28), resting against the wall of a circumferential inner skirt (38) of said retaining ring (14), for making a one-way valve for the compensation air;- an inner lip (29) configured to seal said no-load pneumatic spring, sliding in contact with the wall of said hollow stem (5).

4. The dispenser (1) according to claim 3, wherein said containment body (2) comprises a conical stretch (17) defined for compressing said circumferential widening (27) of the upper seal (11), guaranteeing the sealing of said no-load pneumatic spring.

5. The dispenser (1) according to any one of claims 2 to 4, wherein said upper seal (11) comprises a circumferential outer wall (39) provided with a plurality of axial slots (30), configured to define an air compensation path which passes through a circumferential gap delimited between said circumferential outer wall (39) of said upper seal (11) and said containment body (2).

6. The dispenser (1) according to any one of the preceding claims, wherein said containment body (2) has a compensation hole (34) configured to define an air compensation path.

7. The dispenser (1) according to any one of claims 2 to 6, wherein said lower seal (12) is made in the form of an annular element provided with an outer protrusion (35) having two undercuts; said outer protrusion (35) being configured for making a seal with said containment body (2).

8. The dispenser (1) according to any one of claims 2 to 7, wherein said lower seal (12) is made in the form of an annular element provided with an inner protrusion (36) having two undercuts; saidinner protrusion (36) being configured for making a seal with said hollow stem (5).

9. The dispenser (1) according to any one of claims 2 to 8, wherein said inner protrusion (36) of said lower seal (12) is, in a condition of use, resting on the top with said shoulder (22) of said hollow stem (5) to allow the movement downwards of the lower seal (12) under the pushing action of the hollow stem (5) during a step of actuating the dispenser (1) and, vice versa, the opposite movement, upwards, of the hollow stem (5) pushed by the lower seal (12), during a raising step which returns the slidable parts of the dispenser (1) to a raised rest position.

10. The dispenser (1) according to any one of the preceding claims, wherein the retaining ring (14) defines:- a non-operating closed or stop position, wherein said dispensing head (13) of the dispenser (1) cannot be actuated, and- an operating position wherein the dispensing head (13) can move from a raised or rest position to a lowered end of stroke position; said raised position being defined at a height lower than the height at which said stop position is defined.

11. The dispenser (1) according to claim 10, wherein the difference in height between said raised position and said stop position determines the opening of a path for discharging air for said no- load pneumatic spring.

12. The dispenser (1) according to claim 10 or 11 when dependent on claim 2, wherein said shoulder (22) of the hollow stem (5) is configured for making contact, in said stop position, with said inner lip (29) of the upper seal (11) defining a path for discharging air for said no-load pneumatic spring through said grooves (37) of said shoulder (22).

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