Plastic spring

Abstract

The invention relates to a plastic spring (11) for use in a pump dispenser (13), comprising a first spring element (15) and a second spring element (17), which can be pushed into one another in the axial direction, the spring force is generated in such a way that the first spring element and / or the second spring element (15, 17) elastically extends in the radial direction when the two spring elements (15, 17) are pushed into each other in the axial direction. The first spring element and the second spring element respectively have a first cone and a second cone (15, 17) with a first tip and a second tip (15, 17), the first tip and the second tip (19, 21) face each other, and the first cone (15) can be axially pushed into the second cone (17), or the second cone (17) can be axially pushed into the first cone (15).

Description

TECHNICAL FIELD

[0001] The invention relates to a plastic spring for use in a pump dispenser according to the preamble of claim 1 and to a pump dispenser according to the preamble of claim 12. PRIOR ART

[0002] Pump dispensers are used to take up liquid, which can also have an increased viscosity (cream or gel), from a storage container by pressing on the dispenser head. A dispenser extension is formed on the dispenser head and thus moves together with the dispenser head. A metal spring is integrated into the dispenser for returning the dispenser head to its previous position. A valve function, which is necessary for delivering the liquid into the dispenser extension when the head is pressed and for sucking the liquid back into the pump dispenser when the head is returned, is realized by a metal or glass ball.

[0003] A processing by type of such pump dispensers known from the prior art is not possible or can only be realized with a very great effort, since the metal spring and the valve ball have to be taken out of the pump dispenser.

[0004] Pump dispensers with plastic balls with valve function and a plastic spring adapted in design already exist. In order for the plastic spring to work reliably and to have good durability, the pump dispenser has to be adapted to the plastic spring. This requires a considerable effort, since a pump dispenser has to be developed and produced specifically for the plastic spring. Furthermore, conventional plastic springs, which are usually constructed as a coil spring element, prove to be very complex to manufacture. Complex injection molds and manufacturing techniques have to be available to produce such coil spring structures.

[0005] OBJECT OF THE INVENTION In view of the disadvantages of the prior art, it is the object of the present invention to provide a plastic spring which has a simple structure and can be produced and manufactured as easily as possible, which does not require complex and correspondingly expensive modifications of the pump dispenser, and which can be compressed and decompressed without disruptive jolting movements. DETAILED DESCRIPTION

[0006] The object is achieved in the case of a plastic spring for use in a pump dispenser by the features listed in the characterizing part of claim 1. The dependent claims relate to developments and / or advantageous alternative embodiments.

[0007] The invention is preferably characterized in that the first spring element and the second spring element each have a first cone and a second cone with a first tip and a second tip, wherein the first tip and the second tip face each other and the second cone can be pushed axially into the second cone or the second cone can be pushed axially into the first cone. By providing these two cones, the plastic spring has a particularly simple structure and can be manufactured economically and efficiently. Since the spring consists of only two components, it works particularly reliably and ensures a large number of pump cycles.

[0008] In a preferred embodiment of the invention, the first cone is a truncated cone with a first end or first tip with a smaller diameter and a second end with a larger diameter, the first cone is formed by at least a first side surface and is open at its first end, wherein at least one groove extending from the first end to the second end is provided on the first side surface. The conical shape makes it possible to achieve a maximum spring force of the spring when the penetration depth is maximum in a simple manner. Thus, when the product begins to be sucked into the metering chamber, the restoring force is maximum and the highest suction force is required.

[0009] Of course, it is also conceivable that the second cone is a truncated cone with a third end or second tip with a smaller diameter and a fourth end with a larger diameter, the second cone is formed by at least a second side surface and is open at its third end, wherein at least one groove extending from the third end to the fourth end is provided on the second side surface. It makes no difference for the function of the plastic spring which of the two cones the at least one groove is provided on.

[0010] It proves advantageous if the at least one groove is closed at the first or third end and open at the second or fourth end. Thus, at least one spring arm is formed on the conical side surface, which can open at the second or fourth end. An engagement is formed at the first or third end, around which the spring arm can pivot in the radial direction. Since the engagement is curved in the circumferential direction of the cone, it has a restoring force and the spring arm is pressed back into its initial position. The spring arm can exert a pressure on the other cone at its open end, thereby pushing the inner cone out of the outer cone. This generates an axial force that pushes the inner cone out of the outer cone.

[0011] In a further particularly preferred embodiment of the application, four slots are provided on the first or second cone, wherein in each case a spring arm is formed between the slots. This number of slots or spring arms generates an optimal spring force. It is also conceivable to use a different number of slots or spring arms in order to generate a suitable spring force for a particular application. In particular, by way of a targeted modification of the design of the two cone structures, the spring force can be set in accordance with defined target values. The wall thickness of the slotted cone, the number of slots, the cone angle, the diameter of the cone and the plastic used itself influence the bending stiffness of the cone arm element and thus have a significant influence on the resulting spring force.

[0012] It has proven advantageous for a shoulder to be provided at the second or fourth end, which limits the axial movement of the two cones relative to one another. Thereby, the minimum height of the plastic spring at its maximum compression can be specified in a simple manner.

[0013] Advantageously, the first and second cones have substantially the same height. Thus, only the minimum amount of plastic required is used to manufacture the cones, since neither of the two cones has an unnecessarily large height.

[0014] In a further particularly preferred embodiment of the application, the first and second cones are implemented as sleeves. At least the cone that is penetrated by the other cone must be formed as a sleeve. In order to transport the product between the inlet of the metering chamber and the outlet of the metering chamber, the two cones must be hollow and have the shape of a sleeve.

[0015] It has proven advantageous for the first or second holding element to adjoin the first or third end, respectively. Thus, the plastic spring can be integrated into a standard pump dispenser. The holding elements can be designed such that they are held firmly to the pump dispenser, thereby axially stabilizing the plastic spring and preventing it from buckling in the radial direction when compressed.

[0016] Advantageously, the first and second holding elements are first and second cylindrical side surfaces, which can be connected to components of the pump dispenser in a form-fitting manner. For example, the first cylindrical side surface can fit onto the piston and the second cylindrical side surface is connected to the bottom of the metering chamber.

[0017] It is preferred that the plastic spring is made of polypropylene or polyethylene. If the plastic spring according to the invention is used in a pump dispenser made of the same material as the plastic spring, this constitutes, as is known, an ideal prerequisite for the plastic spring and / or the pump dispenser to be recycled. Alternative materials can also be engineering plastics, such as polyester, polyoxymethylene or polyamide. In particular, polyoxymethylene or polyamide are resistant to friction, thus preventing damage to the two cones caused by the friction of the spring arms with the corresponding conical side surface. The spring can be subjected to up to 5,000 operating cycles without being destroyed.

[0018] A further aspect of the invention relates to a pump dispenser according to the preamble of claim 12. The invention is further characterized in that the spring is a plastic spring according to the above description, and the first and second balls are made of plastic. The spring has the advantage that it can be inserted into a metering chamber of a previously known and thus commercially available pump dispenser. In such a pump dispenser, all components are made of plastic. Thus, a type-specific treatment of the pump dispenser is possible, and it can be fed into a recycling circuit without effort.

[0019] Further advantages and features will become apparent from the following description of embodiments of the invention with reference to the schematic drawings. In the drawings, in schematic views not drawn to scale: Figure 1 : an isometric view of the plastic spring is shown; Figure 2 : a bottom view of the plastic spring of Figure 1 is shown; Figure 3 : a top view of the plastic spring of Figure 1 is shown; Figure 4 : a side view of the plastic spring of Figure 1 is shown; Figure 5 : a sectional view of the spring of Figure 1 along the line IV-IV is shown; Figure 6 : a sectional view of an embodiment of a pump dispenser is shown, in which the plastic spring is installed.

[0020] Figures 1 to 6 A plastic spring is shown, which is generally designated by the reference numeral 11. The plastic spring is intended to be installed in a pump dispenser 13, as shown in Figure 6 . The plastic spring 11 is here in contact with the product to be pumped.

[0021] The plastic spring 11 has a first cone 15 and a second cone 17. Both cones preferably have the shape of a truncated cone in each case, which has a first end 19 and a third end 21, the diameter of which is smaller than the diameter of a second end 23 and a fourth end 25. The first and third ends can also be referred to as tips.

[0022] The first end 19 and the third end 21 face each other, and the second cone 17 can be pushed axially into the first cone 15. The first and second cones are preferably implemented as first and second sleeves 13, 15, i.e. the two cones are hollow.

[0023] The first cone 15 has a plurality of slots 26, preferably four slots 26. Between two adjacent slots 26 in each case a spring arm 27 is formed, which can be pivoted in a hinged manner in the radial direction at the second end 23. At the first end 19, the slots 26 are open, and at the second end 23, the slots 26 are closed. Thus, when the second cone 17 is pushed into the first cone 15, the spring arms 27 can fold outwards.

[0024] At the fourth end 25, a shoulder 28 is provided, which limits the penetration depth of the second cone 17 into the first cone 15 in the axial direction. At the end of the penetration path, the first end 19 rests against the shoulder 28. It is preferred that a first height 29 of the first cone 15 and a second height 30 of the second cone 17 are equal.

[0025] In each case, a first and a second retaining element are adjoined to the second end 23 and the fourth end 25, respectively, in the form of a first and a second cylindrical side surface 31a, 31b. The cylindrical side surfaces can be fitted to components of the pump dispenser 13, thereby stabilizing the spring 11 in the axial direction when sliding in and out.

[0026] In Fig. 8, the spring 11 is integrated into a pump dispenser 13. The pump dispenser has a housing 35 which is held on the container by a cap 37. Preferably, the cap is a screw cap 37 which can be screwed onto the neck of the container. A dosing chamber 39 is formed in the housing 35. The dispenser 13 further comprises a pump head 41 which can be moved up and down relative to the housing 35 along a longitudinal axis 43 of the dispenser 11 between a first position and a second position in order to perform a pump stroke. A plunger 45 which is fixed to the pump head 41 is movable in the dosing chamber 39 in order to deliver liquid. A dispenser opening 47 is connected to the dosing chamber 39. Dosed liquid can exit the pump dispenser 13 through the dispenser opening 47. The plastic spring 11 resets the pump head 41 relative to the housing 35. The valve is realized by a first plastic ball 49a and a second plastic ball 49b. The balls 49a, 49b define the direction of delivery of liquid from the container into the dispenser opening 47 and prevent delivery in the opposite direction. Liquid is sucked from the container into the dosing chamber via a suction tube 51.

[0027] When the pump head 41 is pressed downwards, the second cone 17 penetrates into the first cone 15. Due to the pressure, the spring arms 27 are pushed outwards and, due to their hinged connection with the second end 23, the spring arms are under pre-load. The second cone 17 can be moved axially into the first cone 15 until the first end 19 abuts the shoulder 28. If no axial pressure is applied to the pump head 41, the spring arms 27 under pre-load return to their basic position. Due to the conical configuration of the second sleeve 17, the spring arms can push the second sleeve upwards. Polypropylene or polyethylene are suitable as polymers for manufacturing the spring 11. Since the open ends of the spring arms 27 rub against the side surface of the second cone 17, it is advantageous that the plastic spring 11 is made of a friction-resistant plastic, such as polyoxymethylene or polyamide.

[0028] In the dosing chamber 39, the plastic spring 11 is in contact with the liquid.

[0029] The pump dispenser 13 is completely composed of plastic parts, since the spring 11 and the balls 49a, 49b are also made of plastic. Thereby, the type-specific disposal of the pump dispenser can be achieved with little effort. There is no longer a need to laboriously separate metal parts.

[0030] The plastic spring 11 has the further advantage that it can be designed in such a way that it can be integrated into commercially available pump dispensers 13. Thus, the pump dispenser 13 can be received from mass production.

[0031] List of reference signs : 11 plastic spring 13 pump dispenser 15 first cone, first frustum, first sleeve, first spring element 17 second cone, second frustum, second sleeve, second spring element 19 first end, first tip of the first cone 21 third end, second tip of the second cone 23 second end of the first cone 25 fourth end of the second cone 26 slot 27 spring arm 28 shoulder 29 first height 30 second height 31a, 31b first and second cylindrical side surface, first and second retaining element 35 housing 37 cap 39 dosing chamber 41 pump head 43 longitudinal axis 45 piston 47 dispenser opening 49a, 49b first and second plastic ball 51 suction tube

Claims

1. A plastic spring (11) for use in a pump dispenser (13), the plastic spring having - a first spring element (15) and a second spring element (17), which can be pushed into each other in the axial direction, wherein a spring force is generated by the first spring element and / or the second spring element (15, 17) elastically expanding in a radial direction when the two spring elements (15, 17) are pushed into one another in an axial direction, characterized in that the first spring element and the second spring element each have a first cone and a second cone (15, 17) with a first tip and a second tip (15, 17), wherein the first tip and the second tip (19, 21) face one another and the first cone (15) can be pushed axially into the second cone (17) or the second cone (17) can be pushed axially into the first cone (15).

2. The plastic spring of claim 1, wherein the first cone is a truncated cone (15) with a first end (19) or the first tip with a smaller diameter and a second end (23) with a larger diameter, the first cone is formed by at least a first side surface and is open at its first end (19), wherein at least one slot (26) extending from the first end (19) to the second end (23) is provided on the first side surface.

3. The plastic spring of claim 1, wherein the second cone is a truncated cone (17) with a third end (21) or the second tip with a smaller diameter and a fourth end (25) with a larger diameter, the second cone is formed by at least a second side surface and is open at its third end (21), wherein at least one slot (26) extending from the third end (21) to the fourth end (25) is provided on the second side surface.

4. The plastic spring according to claim 2 or 3, characterized in that the at least one slot (26) is closed at the first or third end and open at the second or fourth end (23, 25).

5. The plastic spring according to any one of claims 2 to 4, characterized in that, four slots (26) are provided on the first or second cone (15, 17), wherein in each case a spring arm (27) is formed between the slots (26).

6. Plastic spring according to one of the preceding claims, characterized in that a shoulder (28) is provided at the second or fourth end (23, 25), which limits the axial movement of the two cones (15, 17) relative to one another.

7. Plastic spring according to one of the preceding claims, characterized in that the first cone and the second cone (15, 17) have essentially the same height (29, 30).

8. Plastic spring according to one of the preceding claims, characterized in that the first cone and the second cone are realized as a first sleeve and a second sleeve (15, 17).

9. The plastic spring according to any one of claims 2 to 8, characterized in that, a first holding element or a second holding element (31a, 31b) is connected to the first or third end (19, 21).

10. The plastic spring of claim 9, wherein, the first holding element and the second holding element are a first cylindrical side surface and a second cylindrical side surface (31a, 31b) which can be connected to a component of the pump dispenser (13) in a form-fit manner.

11. Plastic spring according to one of the preceding claims, characterized in that the plastic spring (11) is made of polypropylene, polyethylene, polyoxymethylene or polyamide.

12. A pump dispenser (13) for metered withdrawal of a liquid from a container, which pump dispenser (13) can be placed on the container, which pump dispenser has - a housing (35), which can be placed on the container (37) and in which a metering chamber (39) is formed, - a pump head (41), which can be moved up and down relative to the housing (35) along a longitudinal axis (43) of the dispenser (13) between a first position and a second position in order to perform a pump stroke, - a piston (45), which is fixed to the pump head (41) and which can be moved in the metering chamber (39) in order to deliver the liquid, - a dispenser opening (47), which is connected to the metering chamber (39) and through which metered liquid can leave the pump dispenser (13), - a spring (11), which resets the pump head (41) relative to the housing (35), and - a suction tube (51), with which liquid is drawn from the container into the metering chamber (39), and - a valve in the form of a first and a second ball (49a, 49b), which balls (49a, 49b) define a delivery direction of the liquid from the container to the dispenser opening (37) and prevent delivery in the opposite direction, characterized in that the spring is a plastic spring (11) according to one of the preceding claims, and the first and the second ball (49a, 49b) are made of plastic.

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