Hand-operated pump

Abstract

Manually operated pump (1), having a cup-shaped main body (2) in which a piston (3) is sealed, which is connected for its movement to a hollow shaft (4) against a spring (20) in the cup-shaped main body (2), the pump having a base (5) which encloses the cup-shaped main body (2) and is provided with a bore (11) for the shaft (4), at least part of the cup-shaped main body (2) and the piston (3) defining a compression chamber (6) which is connected to at least one suction valve element (8) and a discharge valve element (9), the discharge valve element (9) being in communication with a cavity of the piston shaft (4), characterized in that the spring (20) is made in one piece from polyetherimide, a section of the spring winding being dimensioned such that a circle (C) with a diameter between 0.5 mm and 1.5 mm, preferably 0.8 mm, is inscribed therein.

Description

Technical field

[0001] The present invention relates to a hand-operated pump.

[0002] In particular, it is a hand-operated pump for cosmetic or medical products such as creams, sprays, perfumes, etc. STATE OF THE ART

[0003] The familiar hand-operated pumps consist of a multitude of interconnected parts. Most of these parts are made of plastic.

[0004] An important component of hand-operated pumps is the spring, which is made of metal.

[0005] Attempts have been made to manufacture springs from plastics. However, none of the known springs offer comparable performance to metal springs and are stable over the long term. SUMMARY OF THE INVENTION

[0006] The aim of the present invention is to provide a hand-operated pump which represents an improvement on the known technology.

[0007] Another object of the invention is to provide a pump that consists entirely of plastic parts and thus does not require any metal parts.

[0008] Another object of the present invention is to provide a pump that is more environmentally friendly and / or recyclable than the known pumps.

[0009] These and other purposes are achieved by a hand-operated pump made in accordance with the technical teachings of the appended claims. BRIEF DESCRIPTION OF THE CHARACTERS

[0010] Further features and advantages of the invention will become apparent from the description of a preferred but not exclusive form of the hand-operated pump, shown in the accompanying figures by way of example and therefore not limitingly, in which Fig. Figure 1 is a sectional view, in which some parts are shown schematically in dashed lines, of a hand-operated pump according to the invention in an upper end-run position; Fig. 2 is the same cut as in Fig. 1, but shown in a simplified manner, with the pump in a lower end-run position; Fig. 3 is a detailed view of part of the pump from Fig. 1; and Fig. 4 is an axial section through the part in Fig. 3. DETAILED DESCRIPTION OF THE INVENTION

[0011] In the above figures, a hand-operated pump is shown under the reference number 1.

[0012] The hand-operated pump 1 consists of a cup-shaped main body 2 in which a piston 3, connected to a hollow shaft 4 for its movement, slides tightly into the cup-shaped main body 2, as opposed to a spring 20.

[0013] Advantageously, the cup-shaped main body and the piston shaft can be made of PP. The piston 3 is preferably made of PE, LDPE, or PP.

[0014] The pump has a base 5 which encloses the cup-shaped main body 2 and is provided with a bore 11 for the shaft 4.

[0015] At least a part of the cup-shaped main body 2 and the piston 3 define a compression chamber 6 which is connected to at least one inlet valve element 8 and one outlet valve element 9, the outlet valve element 9 being in communication with a cavity 4A of the piston shaft 4.

[0016] According to the invention, the spring 20 is made of polyetherimide (PEI) in one piece.

[0017] The density of the plastic (PEI) from which the spring is made can be between 1.2 g / cm 3 and 1.35 g / cm 3 preferably 1.27 g / cm 3 .

[0018] Advantageously, the polyetherimide from which the spring 20 is made has a tensile modulus between 3000 and 3500 MPa, preferably 3200 MPa (ISO 527 test, 1 mm / min) and / or a flexural modulus between 3000 and 3500 MPa, preferably 3300 MPa (ISO 178 test, 2 mm / min).

[0019] Advantageously, the spring 20 and the base 5 are made in one piece from the same plastic material defined above, preferably by injection molding.

[0020] A free end 20B of the spring can meet a flange 4C, which preferably consists of a piece of the shaft 4.

[0021] The spring 20 may have a free end 20B in the form of a flange.

[0022] The shaft 4 may have, at least over part of its length, an outer diameter D1 which is only slightly smaller than the inner diameter D2 of the spring 20, so that it serves as a deformation guide for the spring 20.

[0023] In addition, the cup-shaped main body may form a chamber 2A that restrains the lateral movement of the spring

[0024] The base 5 can meet the piston 3 when the latter is in an upper end-stroke position, the base extending by a calibrated height H1 into the interior of the cup-shaped main body so as to define a volume of the compression chamber 6, the spring stiffness preferably being related to the height H1.

[0025] The spring-base system, in which the base protrudes a calibrated height into the cup-shaped main body, determines the volume delivered by the pump with each actuation.

[0026] As already mentioned, the spring 20 and the base can be manufactured in two separate parts.

[0027] For this purpose, the spring 20 may have a flange (not shown) opposite the 20B, which rests on a surface of the base 5 suitable for receiving it.

[0028] If you want to change the dosing volume, simply use a socket 5 (or a spring-socket system) with a different H1 height (in particular, a higher H1 height for a smaller volume and a lower H1 height for a larger volume).

[0029] The spring 20, especially its stiffness, can be precisely tuned to the pump's displacement. Thus, the spring stiffness can be related to the height H1, on which the pump's displacement depends.

[0030] If the spring and base are made from one piece, no assembly errors can be made, for example by using a spring with the wrong stiffness for a pump that delivers a certain volume.

[0031] The shaft 4 may have a final stroke configured to impact the base 5 before the spring 20 is fully compressed.

[0032] The final stroke (and the corresponding diameter) is particularly useful for guiding the spring during spring work.

[0033] This is especially true for a spring made of plastic, polyetherimide, so as not to stretch it and impair its function.

[0034] The pump may comprise a sleeve 21 connecting the cup-shaped main body 2 and a container to which the pump 1 is associated, the sleeve preferably being snapped onto the cup-shaped main body 2.

[0035] Advantageously, when connecting to the container, which has, for example, a threaded neck, a seal G can be inserted between the main body in cup form and the container itself.

[0036] Advantageously, this seal G can be made of PP or PE or LDPE, as can the sensor connected to the spring (not shown).

[0037] The shaft 4 may be substantially fixedly connected to a dispensing button 22; the dispensing button 22 preferably has a projection 22A that is fixedly inserted into an enlarged cavity 4D of the shaft 4. Of course, the button 22 may also be mounted and sealed outside the shaft.

[0038] For efficient assembly of the pump motor (motor), the shaft 4 can consist of a first 4B and a second 4E part, which are clicked into each other and are both advantageously made of PP.

[0039] The stem is then assembled by placing the spring 20-socket 5 system on the first piece 4B of the stem and snapping this assembly onto the second piece 4E of the stem, on which the piston 3 was previously mounted.

[0040] The spring-socket system can also snap together with the cup-shaped main body 2, e.g. via an undercut 40.

[0041] In this way, after assembly, the motor can be handled as a self-contained, “finished” unit, i.e. for subsequent connection with sleeve 21 and knob 22, which are also preferably made of polypropylene (PP).

[0042] At the end of the description, it is pointed out that the piston 3 can be pushed onto the shaft 4 and, in cooperation with the shaft itself, can form the outlet valve element 9.

[0043] The piston, rising due to the pressure in the compression chamber 6, releases a passage 30 connecting the cavity 4A of the piston rod to the compression chamber, precisely for the delivery

[0044] With particular reference to Fig. 4 the structure of the spring 20 is explained in more detail.

[0045] The spring 20 can advantageously consist of three coils, but the number of coils can also be between 2.5 and 5.

[0046] The pitch P of the spring can advantageously be between 4 mm and 8 mm, preferably 5.4 mm.

[0047] The effective height E of the spring 20, i.e., the height between the two flanges or between the flange and the base, can be between 13 and 25 mm, preferably 16.2 mm. Of course, the effective height is strongly influenced by the number of coils.

[0048] Advantageously, the ratio of the effective height E to the number of turns is between 5 and 6, advantageously 5.4.

[0049] The total height A of the spring 20, i.e. the total height between the two flanges, excluding the base 5 - if integrated into the spring - can be between 15 mm and 28 mm, preferably 19 mm.

[0050] The maximum thickness B of each turn can be between 1.8 and 4 mm, preferably 2.64 mm.

[0051] This maximum thickness B naturally depends on the shape of the winding section.

[0052] It is advantageous that the maximum thickness B is related to the spring pitch P (and consequently the effective height E) of the spring 20.

[0053] In order to prevent the coils of the spring from becoming flat at the end-run position, it is advantageous that the ratio between the spring pitch P and the maximum coil thickness B is between 1.8 and 2.5, preferably greater than 2, even better 2.045.

[0054] The winding section is dimensioned so that a circle C with a radius of 0.5 to 1.5 mm, preferably 0.8 mm, can be inscribed (in this section).

[0055] The radius of the circle C can correspond to the outer radius R of the individual turns.

[0056] The angle Ω useful for releasing the spring 20 from the mold may be between 20° and 55°, preferably 40°.

[0057] The dimensioning of the spring section 20 results from the definition of a circular section (specifically with radius R) to which material is "added" to facilitate molding and removal from the injection mold, thus creating the angle Ω described above and defining the final shape of the spiral section.

[0058] As in Fig. As can be seen in Figure 4, the coil section is essentially trapezoidal in shape with a small, circularly curved base.

[0059] Other shapes that can be used for the same purpose are a pure trapezoidal cross-section (with connected edges), a rhomboidal cross-section (also with connected edges), or an elliptical cross-section.

[0060] In any case, the radius of the circle inscribed in the winding section is between 0.5 and 1.5 mm, preferably 0.8 mm.

[0061] The weight of the spring 20 (alone or with the base 5) is advantageously less than 3.9 percent of the total weight of the finished pump, including a dipstick (not shown) and a cap (or end cap, also not shown) which can be removably attached to the sleeve 21.

[0062] Even more advantageous is that the weight of the spring 20 is less than 3.5% of the total weight of the finished pump and the associated PP container.

[0063] This ensures that the pump of the present invention can be recycled within the recycling class of polypropylene (PP).

[0064] Various forms of implementation of the invention have been described, but others can also be designed using the same innovative concept.

Claims

[1] A hand-operated pump (1) comprising a cup-shaped main body (2) in which a piston (3) is sealed and connected to a hollow stem (4) for its movement by a spring (20) in the cup-shaped main body (2), the pump comprising a base (5) enclosing the cup-shaped main body (2) and provided with a bore (11) for the stem (4), at least a portion of the cup-shaped main body (2) and the piston (3) defining a compression chamber (6) connected to at least one suction valve element (8) and one discharge valve element (9), the discharge valve element (9) communicating with a cavity of the piston stem (4), characterized by that the spring (20) is made in one piece from polyetherimide, wherein a section of the spring coil is dimensioned such that a circle (C) with a diameter between 0.5 mm and 1.5 mm, preferably 0.8 mm, is inscribed therein. [2] Pump (1) according to claim 1, wherein the density of the polyetherimide from which the spring (20) is made is between 1.2 g / cm 3 and 1.35 g / cm 3 , preferably 1.27 g / cm 3 , lies. [3] Pump (1) according to claim 1, wherein the tensile modulus of the polyetherimide from which the spring (20) is made is between 3000 and 3500 MPa, preferably 3200 MPa, and / or wherein the flexural modulus is between 3000 and 3500 MPa, preferably 3300 MPa. [4] Pump (1) according to claim 1, wherein the base (5) is configured integrally with the spring (20). [5] Pump (1) according to claim 1, wherein the shaft (4) has, at least over part of its length, an outer diameter (D1) which is slightly smaller than an inner diameter (D2) of the spring (20), so that it acts as a deformation guide of the spring (20). [6] Pump (1) according to claim 1, wherein the base (5) meets the piston (3) when the latter is in an upper end-stroke position, the base extending a calibrated height (H1) into the interior of the cup-shaped main body so as to define a volume of the compression chamber (6), the spring stiffness being related to the height (H1). [7] Pump (1) according to claim 1, wherein the shaft (4) has an end stroke (23) configured to impact the base (5) before the spring (20) is fully compressed. [8] Pump (1) according to claim 1, wherein the shaft consists of a first (4B) and a second part (4E) which are connected to one another by a snap connection. [9] Pump (1) according to claim 1, wherein the piston (3) sits smoothly on the piston shaft (4) and, in cooperation with the piston shaft itself, forms the outlet valve element (9). [10] Pump according to claim 1, wherein the ratio between the pitch (P) of the spring and the maximum thickness (B) of the coil is between 1.8 and 2.5, preferably greater than 2, more preferably 2.

045. [11] A pump according to claim 1, wherein the pump (1) comprises a sleeve (21), a dispensing button (22), a seal (G), a receiving tube and a cap removably attached to the sleeve, all made of polypropylene, the weight of the spring (20) being less than 3.9% of the total weight of the pump.

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