Plastic spring

Abstract

The invention relates to a plastic spring (11) for use in a pump dispenser (13), comprising at least one first and one second helical spring strip (17, 19) which are twisted into each other and accordingly form a first double helix; a plurality of first connecting pieces (21a), which connect the first and the second spring strip (17, 19) to each other in the axial direction; and a first and a second ring (24, 25), wherein the upper and lower ends (23a, 23b, 23c, 23d) of the spring strips (17, 19) are connected to the first and the second ring (24, 25), respectively. At least one third and one fourth helical spring strip (26, 27) are connected by their upper ends (23e, 23f) to the free side of the second ring (25). The winding directions of the third and fourth spring strips (26, 27) are counter to the winding directions of the first and second spring strips (17, 19), and the third and fourth spring strips (26, 27) form a second double helix. The lower ends (23g, 23h) of the third and fourth spring strips (26, 27) are connected to a third ring (28).

Description

[0001] plastic spring

[0002] Field of the invention

[0003] The invention relates to a plastic spring for use in a pump dispenser according to the preamble of claim 1 and a pump dispenser according to the preamble of claim 13.

[0004] State of the art

[0005] Pump dispensers are used to dispense a liquid, which may have a higher viscosity (creams or gels), from a storage container by pressing down on a dispenser head. The dispenser extension is formed on the dispenser head and therefore moves with it. A metal spring is integrated into the dispenser to reset the dispenser head. The valve function, which is necessary to ensure that the liquid is pumped into the dispenser extension when the head is pressed and that liquid is drawn back into the pump dispenser when the head is returned, is implemented using metal or glass beads.

[0006] A separate disposal of such pump dispensers known from the state of the art is not possible or only possible with great effort, since the metal spring and the valve balls would have to be removed from the pump dispenser.

[0007] Pump dispensers with plastic balls that function as valves and plastic springs with an adapted design already exist. For example, a pump dispenser with a plastic spring consisting of two or more intertwined threaded spring bands is available on the market. The two spring bands are connected by a plurality of stabilizing bars. Due to the threaded design of the bands, this spring undergoes a torsional twist when compressed, which negatively impacts the function of the pump dispenser. This negative influence must be suppressed or compensated for in a complex manner through geometric adjustments to the other parts of the pump dispenser.

[0008] Object of the invention

[0009] The disadvantages of the described prior art give rise to the task of improving a generic plastic spring in such a way that torsional distortion does not occur. Description

[0010] The stated problem is solved in a plastic spring for use in a pump dispenser by the features stated in the characterizing portion of patent claim 1. Further developments and / or advantageous embodiments are the subject of the dependent patent claims.

[0011] The invention is characterized in that at least a third and a fourth helical spring band are connected by their upper ends to the free side of the second ring, that the winding directions of the third and fourth spring bands are opposite to the winding directions of the first and second spring bands, wherein the third and fourth spring bands form a second double helix, and that the lower ends of the third and fourth spring bands are connected to a third ring.

[0012] Since the winding direction of the third and fourth spring bands is set in exactly the opposite direction to that of the first and second spring bands, when the spring is compressed they generate a torsion that counteracts the torsion of the first and second spring bands. Due to the design of the plastic spring, the two torsional twists are equal in magnitude and cancel each other out because they are opposite. The plastic spring is therefore torsion-neutral. This eliminates the torsional twist that occurs with state-of-the-art plastic springs. This undesirable torsional twist negatively impacts the function of the pump dispenser and, with conventional springs, must be compensated for by complex adjustments to the pump dispenser's components.

[0013] It proves advantageous if the upper ends of the third and fourth spring bands are arranged at an angle relative to the lower ends of the first and second spring bands on the second ring. This angle distributes the plastic material at the ends of the spring bands around the second ring, preventing any spring hardening in the area of ​​the second ring. The plastic spring therefore has a uniform spring stiffness across its entire length.

[0014] For reasons of symmetry, it is preferred if the rotation of the upper ends of the third and fourth spring bands relative to the lower ends of the first and second spring bands is between 70 and 110 degrees, and preferably between 85 and 95 degrees. This ensures that the four spring band ends are evenly distributed over the circumference of the second ring. If more than two spring bands are provided, it is expedient to distribute the ends evenly over the circumference of the second ring. For example, with three spring bands, the upper and lower ends are preferably rotated by between 55 and 65 degrees.

[0015] Conveniently, the winding direction of the third and fourth spring bands is right-handed if the winding direction of the first and second spring bands is left-handed, or the winding direction of the third and fourth spring bands is left-handed if the winding direction of the first and second spring bands is right-handed. This ensures torsion compensation, regardless of the winding direction of the first double helix.

[0016] In a preferred embodiment of the invention, the third and fourth spring bands are connected to each other in the axial direction by a plurality of second connecting webs. It is preferred if the number of first and second connecting webs is the same. As a result, the third and fourth spring bands are held together to the same extent when compressed as the first and second spring bands, and the spring strength of the third and fourth spring bands is the same as that of the first and second spring bands.

[0017] It proves advantageous if the first and second spring bands, together with the first and second rings, form a first partial spring, and the third and fourth spring bands, together with the second and third rings, form a second partial spring. The provision of the two partial springs creates a plastic spring that has the same properties as a one-piece spring according to the state of the art, but has the significant advantage of being torsion-free during loading and unloading.

[0018] In a particularly preferred embodiment of the invention, the second partial spring is created by mirroring the first partial spring on the second ring. As a result, the two partial springs are identical except for their coil direction.

[0019] Because the first, second, and third rings have identical outer diameters and are arranged concentrically one above the other, the spring has the outer dimensions of a rotating cylinder with a circumferential surface. This facilitates the integration of the spring into a standard pump dispenser.

[0020] It is advantageous if the spring bands extend along the outer surface of the plastic spring. This prevents the spring bands from protruding from the outer surface. Preferably, the spring bands remain attached to the outer surface even in the compressed position, and the outer diameter of the spring remains essentially unchanged.

[0021] In a further preferred embodiment of the invention, the spring strips have a pitch angle of between 20 and 60 degrees, and preferably between 30 and 50 degrees, in the relaxed position of the spring. This gives the spring a compression ratio (the ratio of the lengths of the spring in the unloaded position and in the compressed position) that corresponds to a conventional steel spring.

[0022] It is advisable for the first, second, third and fourth spring bands to be of equal length in order to obtain a plastic spring which has a uniform spring force over its entire length.

[0023] The invention is also preferably characterized in that the plastic spring (11) is made of polypropylene. Polypropylene is cost-effective and has sufficient mechanical strength for a large number of operating cycles of the spring without causing it to be destroyed. The plastic spring can also be made of recycled polypropylene or polyoxymethylene (POM).

[0024] A further aspect of the invention relates to a pump dispenser according to the preamble of claim 14. The invention is also characterized in that the spring is a plastic spring according to the above description. The spring has the advantage that it can be inserted into the dispensing chamber of a previously known and accordingly commercially available pump dispenser. In such a pump dispenser, all components are made of plastic. Accordingly, the pump dispenser can be disposed of separately and recycled without effort.

[0025] Further advantages and features will become apparent from the following description of an embodiment of the invention with reference to the schematic representations. These are not to scale:

[0026] Figure 1 : a plastic spring in a side view;

[0027] Figure 2: a first isometric view of the plastic spring from Figure 1

[0028] Figure 3: a second isometric view of the plastic spring from Figure 1 and Figure 4: a sectional view of a pump dispenser in which the plastic spring is installed.

[0029] Figures 1, 2, 3, and 4 show a plastic spring, designated collectively by reference numeral 11. The plastic spring 11 is intended to be installed in a pump dispenser 13, as shown in Figure 4. The plastic spring 11 comes into contact with the product to be pumped.

[0030] The plastic spring 11 is constructed from a first partial spring 14 and a second partial spring 15. The structure of the first partial spring 14 is generally known from the prior art: The first partial spring 14 has a first and a second helical spring band 17, 19, which are twisted within each other. The first and second spring bands 17, 19 form a first double helix. A plurality of first connecting webs 21a are provided to hold the two spring bands 17, 19 together. These connect the two spring bands 17, 19 multiple times in the axial direction.

[0031] The upper ends 23a, 23b of the spring bands 17, 19 are connected to a first ring 24. The lower ends 23c, 23d are connected to a second ring 25. When the first partial spring 14 is compressed, the first and second spring bands 17, 19 are held together by the first connecting webs 21a. This allows the spring bands 17, 19 to expand radially only slightly during compression. Due to the helical shape, a torsional twist occurs.

[0032] The second partial spring 15 is provided to compensate for this torsional twist. The second partial spring has a third and fourth helical spring band 26, 27, which are also twisted within each other and accordingly form a second double helix. The winding directions of the third and fourth spring band 26, 27 are opposite to the winding directions of the first and second spring bands 17, 19. Therefore, the torsional twist of the second partial spring 15 is also opposite to the torsional twist of the first partial spring, whereby the two torsional twists of the two partial springs 14, 15 cancel each other out. The upper ends 23e, 23f of the third and fourth spring bands 26, 27 are connected to the second ring 25. The lower ends 23g, 23h of the third and fourth spring bands 26, 27 are connected to a third ring 28. The third and fourth spring bands 26, 27 are connected in the axial direction by a plurality of second connecting webs 21 b.The first, second, and third rings 24, 25, 28 have identical outer diameters and are arranged concentrically one above the other in the axial direction. The winding direction of the third and fourth spring bands 26, 27 must be right-handed if the winding direction of the first and second spring bands 17, 19 is left-handed. The winding direction of the third and fourth spring bands 26, 27 must be left-handed if the winding direction of the first and second spring bands 17, 19 is right-handed. The second partial spring 15 is therefore the first partial spring 14, which is mirrored by the second ring 25. Therefore, the two partial springs 14, 15, or the spring bands 17, 19, 26, 27, are preferably of equal length. The sum of the lengths of the first and second partial springs 14, 15 corresponds to the length L of the plastic spring with a double helix according to the prior art and is, for example, between 4 and 100 mm. The choice of length depends on the size of the spring diameter.The spring diameter D can be between 5 and 20 mm. Accordingly, a ratio of L / D between 1 and 5 is preferred. The ratio L / D also depends on the required spring travel of the spring 11. The spring bands 17, 19, 26, 27 extend on the outer surface 31 of the plastic spring 11, the diameter of which is determined by the diameters of the rings 24, 25, 28.

[0033] The upper ends 23e, 23f are arranged at the second circle 25, twisted relative to the lower ends 23c, 23d. This ensures that the spring 11 remains highly compressible even in the area of ​​the second ring 25 and exhibits no undesirable stiffening. For reasons of symmetry, it is preferable for the twist angle to be 90 degrees when two spring bands 17, 19 are present.

[0034] The pitch angle of the spring bands 17, 19, 26, and 27 can be adjusted to suit their length and is also determined by the required restoring force. The pitch angle is preferably between 30 and 50 degrees.

[0035] According to Figure 4, the spring 11 is integrated into a pump dispenser 13. The pump dispenser has a housing 35, which is held to a container by a cap 37. This is preferably a screw cap 37 that can be screwed onto the container neck. A dosing chamber 39 is formed in the housing 35. The dispenser 13 further comprises a pump head 41, which is movable up and down relative to the housing 35 along the longitudinal axis 43 of the dispenser 11 between a first and second position to execute a pump stroke. A piston 45, which is fixed to the pump head 41, is movable in the dosing chamber 39 to convey the liquid. A dispensing opening 47 is connected to the dosing chamber 39. The dosed liquid can leave the pump dispenser 13 through the dispensing opening 47. The plastic spring 11 resets the pump head 41 relative to the housing 35. A valve is realized by a first and second plastic ball 49a, 49b.The balls 49a, 49b define the direction of flow of the liquid from the container into the dispensing opening 47 and block flow in the opposite direction. The liquid is drawn from the container into the dispensing chamber via a suction tube 51.

[0036] In the dispensing chamber 39, the plastic spring 11 comes into contact with the liquid. The pump dispenser 13 is constructed entirely of plastic parts, as the spring 11 and the balls 49a, 49b are also made of plastic. This allows for easy, separate disposal of the pump dispenser. The laborious separation of metal parts is eliminated.

[0037] The plastic spring 11 has the further advantage of being designed to be integrated into a commercially available pump dispenser 13. The pump dispenser 13 can therefore be adopted from mass production. Only the height and diameter of the dosing chamber 39 may need to be slightly adapted to the dimensions of the plastic spring 11.

[0038] Legend:

[0039] 11 plastic spring

[0040] 13 pump dispensers

[0041] 14 First partial spring

[0042] 15 Second partial spring

[0043] 17 First spring band

[0044] 19 Second spring band

[0045] 21a First connecting bridges

[0046] 21b Second connecting bridges

[0047] 23a, 23b Upper ends of the first and second spring band

[0048] 23c, 23d Lower ends of the first and second spring band

[0049] 23e,23f Upper ends of the third and fourth spring bands

[0050] 23g, 23h Lower ends of the third and fourth spring band

[0051] 24 First Ring

[0052] 25 Second Ring

[0053] 26 Third spring band

[0054] 27 Fourth spring band

[0055] 28 Third Ring

[0056] 31 lateral surface

[0057] 35 housings

[0058] 37 cap

[0059] 39 Dosing chamber

[0060] 41 Pump head

[0061] 43 Longitudinal axis

[0062] 45 pistons

[0063] 47 Donor opening

[0064] 49a, 49b First and second plastic ball

[0065] 51 intake manifold

Claims

1. Plastic spring (11) for use in a pump dispenser (13) comprising - at least one first and one second helical spring band (17, 19) which are twisted into each other and accordingly form a first double helix, - a plurality of first connecting webs (21a) which connect the first and the second spring band (17, 19) to each other in the axial direction and - a first and a second ring (24, 25), wherein the upper and lower ends (23a, 23b, 23c, 23d) of the spring bands (17, 19) are connected to the first and the second ring (24, 25), respectively, characterized in that - that at least a third and a fourth helical spring band (26, 27) are connected by their upper ends (23e, 23f) to the free side of the second ring (25), - that the winding directions of the third and fourth spring bands (26, 27) are opposite to the winding directions of the first and second spring bands (17, 19), the third and fourth spring bands (26, 27) forming a second double helix, and - that the lower ends (23g, 23h) of the third and fourth spring bands (26, 27) are connected to a third ring (28).

2. Plastic spring according to claim 1, characterized in that the upper ends (23e, 23f) of the third and fourth spring bands (26, 27) are arranged rotated relative to the lower ends (23c, 23d) of the first and second spring bands (17, 19) on the second ring (25).

3. Plastic spring according to claim 2, characterized in that the rotation of the upper ends (23e, 23f) of the third and fourth spring bands (26, 27) relative to the lower ends (23c, 23d) of the first and second spring bands (17, 19) is between 70 and 110 degrees and preferably between 85 and 95 degrees.

4. Plastic spring according to one of the preceding claims, characterized in that the winding direction of the third and fourth spring band (26, 27) is right-handed when the winding direction of the first and second spring band- of (17,19) is left-handed or that the winding direction of the third and fourth spring band (26,27) is left-handed if the winding direction of the first and second spring band (17,19) is right-handed.

5. Plastic spring according to one of the preceding claims, characterized in that the third and fourth spring bands (26, 27) are each connected to one another in the axial direction by a plurality of second connecting webs (21b).

6. Plastic spring according to one of the preceding claims, characterized in that the first and second spring bands (17, 19) together with the first and second rings (24, 25) form a first partial spring (14) and the third and fourth spring bands (26, 27) together with the second and third rings (25, 28) form a second partial spring (15).

7. Plastic spring according to claim 6, characterized in that the second partial spring (15) is created by mirroring the first partial spring (14) on the second ring (25).

8. Plastic spring according to one of the preceding claims, characterized in that the first, second and third rings (24, 25, 28) have an identical outer diameter and are arranged concentrically one above the other.

9. Plastic spring according to one of the preceding claims, characterized in that the spring bands (15, 17, 26, 27) extend on the outer surface (31) of the plastic spring (11).

10. Plastic spring according to one of the preceding claims, characterized in that the spring bands (15, 17, 26, 27) in the relaxed position of the spring (11) have a pitch angle between 20 and 60 degrees and preferably between 30 and 50 degrees. 11 . Plastic spring according to one of the preceding claims, characterized in that the first, second, third and fourth spring bands (15, 17, 26, 27) are of equal length.

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

13. Pump dispenser (13) for the metered withdrawal of a liquid from a container onto which the pump dispenser (13) can be placed, comprising a housing (35) which is held to the container by a cap (37) and in which a metering chamber (39) is formed, a pump head (41) which is movable up and down relative to the housing (35) along the longitudinal axis (43) of the dispenser (13) between a first and a second position to carry out a pump stroke, a piston (45) which is fixed to the pump head (41) and is movable in the metering chamber (39) to convey 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), a suction tube (51) with which liquid can be drawn from the container into the metering chamber (39). is sucked and a valve in the form of a first and second ball (49a,49b) made of plastic, which balls (49a, 49b) define the conveying direction of the liquid from the container into the dispensing opening (37) and block conveyance in the opposite direction, characterized in that the spring is a plastic spring (11) according to one of the preceding claims.

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