PUMP UNIT AND LIQUID DISPENSER WITH SUCH A PUMP UNIT

Description

SCOPE OF APPLICATION AND STATE OF THE ART

[0001] The invention relates to a pump unit for a liquid dispenser and to a liquid dispenser with such a pump unit.

[0002] A pump unit of this type is part of a liquid dispenser, for example, a dispenser for pharmaceutical liquids or possibly also cosmetic liquids. The pump unit is designed to draw liquid from a reservoir and pressurize it for dispensing through a dispensing opening. Dispensing typically occurs in the form of a spray jet, but can also be in the form of an unatomized jet or individual droplets.

[0003] Pump units of this type are usually designed for manual operation, in particular for operation by pressing down an actuating button, on which the discharge opening may also be provided.

[0004] Typical pump units are usually equipped with a return spring which, after actuation and a resulting reduction in the volume of a pump chamber, combined with the discharge of liquid, pushes the pump unit back into its starting position and thereby moves a pump piston back into its starting position.

[0005] The return spring was traditionally made of metal. However, many liquid dispensers now use a plastic spring. This simplifies recycling, as separating the metallic components from the plastic is no longer necessary.

[0006] It is already known from the prior art to provide pump units whose return spring is integrated in the form of a tension spring. This is described, for example, in US 8622254 B2, US 5267673 A, US 5788124 A, CN 103029895 B, US 2002 / 043540 A1 and US 6227414 B1.

[0007] The known systems feature return springs with parallel individual strands or circumferentially closed sleeve bodies that are extended when the pump is actuated. This design has proven problematic, as it is difficult to find a material that allows for comfortable use with regard to the required actuation force and the desired return force. US Patent 2002 / 043540 A1 discloses the orientation of a sleeve body such that the extension of the return spring is less than the stroke of the pump piston. However, the design described here is quite large and difficult to implement in practice with compact dispensers.

[0008] German patent DE 102021122705A1 discloses a pump device with a return spring in the form of a cage-like structure made of plastic, wherein the spring serves to return the pump piston by elastic deformation upon compression. US patent US 2005 / 006412A1 describes a sample or test dispenser with a pump mechanism in which dosing units can be formed and dispensed by means of a movable element and a plastic return element. WO 2022 / 136609A1 discloses a pump dispenser with a plastic-based return spring, which is constructed from several rings and connecting bridges and deforms when the pump head is actuated by compression. All known solutions have in common that they provide plastic return elements, but are based on a mode of operation in which the spring is subjected to compression. TASK AND SOLUTION

[0009] The object of the invention is to provide a pump unit and a dispenser with such a pump unit, wherein the pump unit has a return spring that simultaneously ensures the desired functionality of the pump unit and enables easy recycling.

[0010] According to the invention, a pump unit for a liquid dispenser and a liquid dispenser with such a pump unit are proposed. The following description focuses primarily on the pump unit. However, the descriptions also apply to a liquid reservoir with such a pump unit.

[0011] The pump unit according to the invention comprises a pump cylinder and a pump piston, which is movable relative to the pump cylinder between an unactuated end position and an actuated end position. The pump cylinder has, at least in a partial section, a cylindrical sealing surface in which the pump piston bears against this sealing surface in a circumferential, sealing manner.

[0012] A pump chamber, surrounded by the pump cylinder and piston, has its maximum volume in the unactuated end position and its minimum volume in the actuated end position. During the actuation-induced reduction of the pump chamber volume, fluid is pumped from the pump chamber towards a discharge opening. During the subsequent return stroke and the associated increase in the pump chamber volume, fluid is drawn from a fluid reservoir into the pump chamber.

[0013] For this purpose, the pump unit has an inlet valve at a liquid inlet of the pump chamber and an outlet valve at a liquid outlet of the pump chamber. During discharge, the outlet valve is open and the inlet valve is closed. During the return stroke, the outlet valve is at least intermittently closed and the inlet valve is open, so that liquid is drawn into the pump chamber through the liquid inlet. As described below, the outlet valve is preferably a valve that opens depending on the overpressure in the pump chamber. The inlet valve can be opened depending on the underpressure in the pump chamber or depending on the stroke.

[0014] The pump unit has a return spring that exerts force on the pump piston in the direction of its unactuated end position. This spring acts between the housing, or more specifically the pump cylinder, of the pump unit on the one hand, and the pump piston on the other. The return spring can be mounted not only on the pump cylinder and piston, but also on components attached to them. In particular, the pump piston itself can also be an integral part of the return spring, as will be explained later.

[0015] According to the invention, this return spring is designed in a special way. The return spring is designed as a tension spring and arranged such that, when the pump chamber is reduced in size, a cylinder-side end and a piston-side end of the return spring are spaced apart from each other in a longitudinal direction, thereby creating or increasing a state of tension in the return spring. When the pump unit is actuated, the piston is thus spaced away from the cylinder-side end of the return spring and the bearing area there, so that the return spring as a whole is subjected to tension.

[0016] The return spring is designed, at least in part, as a cage spring. This means that the section of the return spring designed as a cage spring, or possibly the entire return spring designed as a cage spring, has a circumferential wall with a cylindrical or conical shape. This wall contains openings that form a structure with nodes and spring bars connecting these nodes.

[0017] It has been shown that constructing a tension-return spring as a cage spring offers significant advantages. In particular, it exhibits a reduced tendency to relax. Furthermore, in a cage spring, elastic elongation is not solely caused by material strain, but to a considerable extent by bending deformation. This leads to greater flexibility in the selection of the spring material, as materials that, at a suitable thickness, would result in excessive actuation force under pure tensile stress are also suitable if the return spring is elongated also or predominantly by bending deformation.

[0018] Designing the return spring as a tension spring has the advantage that its shape is defined when under tension. Compression springs, on the other hand, have the problem that they can deform in unpredictable ways, potentially impairing the dispenser's function. The cage spring has proven particularly well-suited to ensuring a defined positional behavior of the return spring during actuation. By selectively strengthening or weakening the nodes and / or spring bars, the deformation of the return spring can be controlled very precisely.

[0019] A cage spring typically has nodes in its wall which, due to the arrangement of the openings, are integrally connected to adjacent nodes or to areas of the return spring adjoining the cage spring by spring bars.

[0020] Preferably, the cage spring has at least four nodes, from each of which at least three spring bars extend to other nodes or to areas of the return spring adjacent to the cage spring. Particularly preferably, at least eight such nodes are provided, or even twelve or more.

[0021] Preferably, the cage spring has spring bars that are integrally attached to a common node and which are spread apart as the ends of the return spring are spaced apart, thereby causing a bending deformation in the respective node.

[0022] The return spring with such spring bars that spread out under load is preferably shaped in such a way that it stores a significant portion of the energy introduced by actuation in the form of bending deformation, i.e., by deformation in which spring bars and nodes of the cage spring are deformed in such a way that compression occurs on one side and elongation on the opposite side.

[0023] It has been shown, particularly with such a spring based on bending deformation, that with such nodes and spring bars there is only a slight tendency to relax and a spring characteristic suitable for pump actuation is easier to achieve here than with a spring that stores energy completely or primarily through tensile stress.

[0024] The energy stored during actuation need not be stored solely through the aforementioned bending deformation in the nodes or spring bars. Additional bending deformation and other elastic deformations can occur in other parts of the return spring. It is considered advantageous if, in a tensioned state of the return spring with the pump piston in the actuated end position, at least 50% of the spring energy of the return spring is stored in the bending deformation of the nodes and spring bars, preferably at least 80%.

[0025] The wall of the cage spring has spring bars on both sides, with openings preferably providing between 8 and 200 openings, and particularly preferably between 12 and 100 openings. Preferably, at least three such spring bars are formed by the openings, but particularly preferably between 12 and 72 spring bars.

[0026] Preferably, the return spring is at least partially made of a polyolefin, preferably polyethylene. Preferably, the return spring is made entirely of polyolefin. However, it is also possible for the return spring to be manufactured as a two-component (2K) part. In such a case, preferably at least the cage spring is made of polyolefin.

[0027] The cage spring has a structure consisting of openings and intervening nodes and spring bars. During dispenser actuation, elastic deformation by bending occurs in the nodes as the cage spring elongates. This bending deformation of the nodes also includes the bending deformation in the transition sections of the spring bars immediately adjacent to the nodes. Specifically, two spring bars integrally connected to a node are joined by a rounded transition at the node, preferably with a minimum radius of curvature greater than 0.5 mm, and particularly greater than 1.0 mm. For the purposes of the invention, this transition radius is considered part of the node.

[0028] Preferably, the cage spring has openings, each bordered by four spring bars, namely two upper and two lower spring bars. One lower and one upper spring bar each form two spring bars connected laterally to the opening by a node. The upper and lower spring bars form spring bars that are connected to each other in a central position relative to the opening by further nodes.

[0029] In such a case, at least some of the openings are defined by a total of four node pieces and a total of four spring bars.

[0030] The cage spring preferably has a circumferential structure of nodes and connecting spring bars, in which the spring bars are connected to nodes at both ends and, in particular, preferably at least some nodes each carry at least two pairs of spring bars. The nodes are preferably arranged longitudinally one behind the other in a row-like fashion, with preferably 4, 6, or 8 rows of nodes being provided and distributed around the circumference of the cage spring.

[0031] At least one of the node pieces, which carries two pairs of spring bars, preferably has a cross-section in a plane orthogonal to the longitudinal direction with a shape tapered towards a central axis of the return spring. Two lateral flanks of the node piece are therefore not aligned parallel, but rather angled radially to the central axis of the cage spring or even beyond this radial orientation. In particular, the cross-section of the node piece can have a triangular cross-sectional area. Depending on the specific design of the cage spring and the manufacturing conditions, the opposite orientation with a shape tapering away from a central axis or a parallel orientation of the flanks can also be advantageous.

[0032] It has been shown that by tapering towards the central axis, stress peaks are reduced and thus the risk of damage to the return spring during operation of the pump unit is reduced.

[0033] Another particular design provides for a plurality of circumferentially distributed nodes connected to each other via a stabilizing ring. Preferably, the circumferential stabilizing ring is formed integrally with the nodes. The stabilizing ring is preferably connected to the nodes of the cage spring in such a way that no bending or other relevant deformation occurs in it when the return spring is stretched.

[0034] Such a stabilizing ring can be helpful in a cage spring to connect nodes arranged on a common geometric plane orthogonal to the longitudinal axis, thus reducing the tendency of the nodes to deflect outwards or inwards during actuation. Instead, the position of the nodes relative to each other remains largely unchanged, and the energy stored in the return spring is primarily stored through the deformation of the spring bars.

[0035] The openings, usually surrounded by knot pieces and four spring bars, can be provided in various special shapes.

[0036] A preferred design provides that the cage spring has openings which, in lateral regions, form a clear longitudinal distance that is larger than a central clear longitudinal distance. The central clear longitudinal distance is preferably zero in the unactuated state of the return spring, meaning that only in two lateral regions of the opening do the opposing surfaces of the return spring not touch each other in the unactuated state.

[0037] The described design is particularly suitable for achieving a high degree of deformation without damaging the return spring. In the aforementioned lateral areas, the return spring component is preferably provided with rounded edges to prevent the return spring from tearing during actuation.

[0038] When the pump cylinder and piston are in the actuated end position, the spring bars on a common node preferably enclose an angle that is between 5° and 50° greater than the angle that the spring bars enclose when the pump cylinder and piston are in the unactuated end position. Preferably, a straight line passing through nodes connected by a spring bar forms an angle of less than 10° with a plane orthogonal to the longitudinal direction when the pump unit is unactuated, and an angle of more than 10° when actuated.

[0039] The return spring can be connected to the pump piston in various ways. For example, a mechanical coupling is possible, which can be achieved, for instance, through a positive fit via matching contours on the return spring and a pump piston component.

[0040] A particularly advantageous feature is a one-piece design in which the return spring has a piston geometry with a circumferential piston lip integrally molded onto its lower end. This piston lip forms the pump piston and, during operation, bears contact with the inside of the cylindrical pump cylinder, at least intermittently. The one-piece design eliminates the need for a positive-locking or force-locking connection between the pump piston and the return spring, which is sufficiently stable under tensile load.

[0041] A single-piece component, comprising the piston lip and spring section with its connecting pieces and spring bars, can be provided. Alternatively, a multi-component injection-molded component is also conceivable, allowing for the application of specific material properties to different sections of the component. In this case, the cage spring and piston lip, in particular, can be made of different materials.

[0042] The return spring, particularly in its one-piece design with an integrally molded piston lip, can also include further functional components. For example, the return spring preferably provides a valve surface of the outlet valve against which a valve section of a valve body rests when the outlet valve is closed. This valve section is preferably designed to expand under the influence of fluid overpressure and be lifted from a valve mating surface, thereby enabling fluid discharge.

[0043] Preferably, the pump unit is designed in which it has an outlet pipe that projects from a discharge side into an interior region of the return spring. The outlet pipe is preferably fixed to an operating handle by means of which the pump unit is manually actuated. The coupling between the return spring and the outlet pipe takes place within the interior of the return spring. For this purpose, the outlet pipe and the return spring preferably have cooperating stop surfaces, so that the return spring can be extended by means of the outlet pipe when it is depressed. The stop surfaces can be oriented orthogonally to a displacement direction of the outlet pipe. It is particularly advantageous if at least one, and preferably both, of the stop surfaces have a conical or otherwise expanding shape. This allows the stop surfaces to interlock.In such a case, the outlet pipe is essentially hooked into the stop surface of the return spring.

[0044] The formation of an outlet valve can be achieved, in particular, by using an outlet pipe of the type described or of another type. The pump unit therefore preferably has an outlet pipe which is inserted into the return spring. A valve component is provided on this outlet pipe. This component can, in particular, be designed as a separate component which is attached to the outlet pipe and, in particular, can be inserted into it.

[0045] The valve component preferably forms a valve surface of the outlet valve, which, in the closed state of the outlet valve, rests against the lower end of the return spring and / or against the inner surface of the pump piston. When the pressure in the pump chamber is sufficiently high, the return spring or the pump piston expands elastically, causing the contact to be lost and the outlet valve to open.

[0046] The valve component can alternatively or additionally be part of the inlet valve. For this purpose, it is preferably provided that the fluid inlet is located in the base of the pump cylinder and that, when the outlet pipe is depressed, a section of the valve component moves into the fluid inlet or shifts within the fluid inlet, thereby closing the inlet valve. This is particularly advantageous when a delayed discharge relative to the actuation of the pump unit is desired, as will be explained further below.

[0047] To connect the return spring to the pump cylinder, it is preferably provided that the return spring has at least one outwardly projecting bearing element at one end to form the cylinder-side spring bearing, for example in the form of a circumferential bearing ring. The return spring is secured to the pump cylinder in a longitudinal direction by means of this bearing element, whereby contact surfaces may be provided on the bearing element and on the pump cylinder for this purpose. Preferably, the contact surface on the bearing element and / or the contact surface on the pump cylinder are aligned orthogonally to an actuation direction, forming a stepped structure, or are provided with a chamfer to prevent the bearing element from slipping off the pump cylinder.

[0048] In a preferred design, the pump unit comprises a cylinder housing and a housing cover to form the pump cylinder. The cylinder housing preferably has two cylindrical sections with different inner diameters in the longitudinal direction: a return spring section with a larger diameter to accommodate the return spring's cage spring, and a pump chamber section with a smaller diameter. The diameter of the pump chamber section is adapted, at least partially, to the outer diameter of the pump piston to define the pump chamber's boundaries. The housing cover is designed to close the pump unit, and in particular its return spring section, at the top. It may be provided with an opening through which an actuating plunger projects, preferably in the form of the aforementioned outlet pipe.

[0049] The return spring can be clamped between the cylinder housing and the housing cover. Preferably, the housing cover and the cylinder housing each have an outwardly projecting mounting flange, with the two mounting flanges abutting directly against each other. The abutting mounting flanges allow the two housing elements of the pump unit—the cylinder housing and the housing cover—to be pressed together and fixed in position by means of a closure on the liquid dispenser, which is attached to a container of the liquid storage system, for example, by means of snap-fit ​​elements or a thread, thus sufficiently securing the cylinder-side spring bearing of the return spring.

[0050] The outlet valve of the pump unit is preferably a pressure-dependent opening outlet valve, i.e., a valve that opens when a structurally predetermined limit pressure has been reached in the pump chamber.

[0051] The inlet valve can also be designed as a pressure-dependent opening valve, which opens when the pressure in the pump chamber has dropped sufficiently below the pressure in the fluid reservoir, creating a vacuum in the pump chamber. However, in a specific design, the inlet valve is configured as a displacement-dependent closing inlet valve, which closes at a defined intermediate position after the pump piston has traveled a certain distance from its unactuated end position to its actuated end position. Additionally, a sealing extension, which engages a metering channel to close the inlet valve, can be provided to reopen this metering channel at the opposite end towards the end of the actuation, thus ending the discharge abruptly and precisely.This also facilitates the commissioning of the dispenser, as it allows any air located in or compressed in the pump chamber to escape into the liquid reservoir during commissioning.

[0052] As an alternative to such a position-dependent closing inlet valve, the pump unit may have a closable outlet channel through which fluid can flow from the pump chamber back into the fluid reservoir and which is only closed after the pump piston has traveled an idle stroke distance when moving from the unactuated end position towards the actuated end position.

[0053] Both designs—the inlet valve closing after a period of idle stroke and the outlet channel closing after a period of idle stroke for the purpose of backflow from the pump chamber into the fluid reservoir—result in no discharge occurring initially when the pump unit is actuated. This is because, at the start of actuation, the fluid in the pump chamber is not yet isolated from the fluid reservoir, and therefore the pressure required to open the outlet valve cannot be built up. Only after the period of idle stroke has been completed is the pump chamber isolated from the fluid reservoir, the pressure in the fluid increases, and discharge begins. The period of idle stroke is at least 5%, preferably at least 10%, of the distance between the actuated and unactuated end positions of the pump piston.

[0054] The delayed fluid discharge caused by the idle stroke is advantageous because it ensures that a uniform amount of fluid can be achieved per actuation, even if the return spring has a length that deviates from the target length in the unactuated state due to relaxation or other aging processes.

[0055] One way to implement an outflow channel of the described type is to align the pump cylinder and pump piston in such a way that, in the unactuated end position, they do not make continuous sealing contact. During the movement of the pump piston towards the actuated end position, continuous sealing contact only occurs after a period of free stroke. Only when continuous sealing contact is established can no more fluid escape from the pump chamber into the fluid reservoir, and continued actuation causes the fluid to be discharged.

[0056] The fact that the pump cylinder and pump piston are aligned in such a way that they do not form a continuous sealing contact in the unactuated end position can be achieved by ensuring that the pump piston is not in contact with the pump cylinder in the unactuated end position, leaving an annular gap between the inner wall of the pump cylinder and the pump piston. Alternatively, a design is possible in which the pump piston, in the unactuated end position, rests against the inner wall of the pump cylinder over a portion of its circumference and is spaced apart from the inner wall of the pump cylinder over another portion of its circumference, forming an outlet channel.

[0057] In both cases, at the beginning of an operation, the fluid can escape from the pump chamber at the pump piston and then return to the fluid reservoir through an outlet opening in the pump cylinder.

[0058] Another possible design involves the pump cylinder having an outlet opening in one of its cylinder walls. This outlet opening is positioned so that it is passed over when the pump piston moves from its unactuated end position to its actuated end position. Until this point, fluid can flow from the pump chamber back into the fluid reservoir. Once the pump piston has passed over the outlet opening, the fluid in the pump chamber is pressurized and thus discharged.

[0059] Although fluid can be forced back from the pump chamber into the fluid reservoir via a displacement-dependent inlet valve, as well as via the aforementioned outlet channel, at a defined intermediate position, the outlet channel is preferred because it prevents a vacuum from forming in the pump chamber during the return stroke. Such a vacuum is undesirable because it necessitates a sufficiently strong return spring to overcome it. The use of an additional outlet channel eliminates this requirement. Therefore, particularly in a pump unit with an outlet channel, it is considered advantageous for the inlet valve to be designed as a pressure-dependent inlet valve that opens when there is overpressure in the pump chamber relative to the fluid reservoir.Such a pressure-dependent opening and closing inlet valve allows liquid to be drawn into the pump chamber almost immediately at the beginning of the return stroke. Preferred inlet valve designs are primarily plate valves or valves with a ball valve.

[0060] The described pump units preferably consist entirely of plastic, in particular exclusively of plastics that can be processed in a common recycling stream. However, the pump unit may also contain small proportions of other plastics or metallic components, provided that their total proportion of the mass of the pump unit does not exceed 10% and preferably 5%.

[0061] A liquid dispenser according to the invention comprises a pump unit according to the invention. In particular, such a liquid dispenser preferably has a liquid reservoir made of plastic. This reservoir preferably has an opening into which the pump unit is inserted and in which the pump unit is preferably fixed by means of a housing cover.

[0062] The liquid reservoir preferably has a total volume of less than 100 ml, particularly less than 50 ml. In its ready-to-sell state, the liquid reservoir is preferably filled with a pharmaceutical or cosmetic liquid. BRIEF DESCRIPTION OF THE DRAWINGS

[0063] Further advantages and aspects of the invention will become apparent from the claims and from the following description of preferred embodiments of the invention, which are explained below with reference to the figures. Fig. 1A und 1B show an uncut representation of a liquid dispenser according to the invention and a pump unit for it. Fig. 2 shows a first variant of a pump unit according to the invention in a cutaway view. Fig. 3A und 3B show different variants of return springs for the pump unit of the Fig. 2 , 5 and 6 . Fig. 4A bis 4C illustrates the deformation of a return spring of the pump unit according to the invention when actuated. Fig. 5 , 6 and 7 show a second, third and fourth variant of a pump unit according to the invention in cutaway view. DETAILED DESCRIPTION OF THE EXECUTION EXAMPLES

[0064] Fig. 1A und 1B Figure 1 shows a liquid dispenser 100 and a pump unit 10 of the liquid dispenser, which is coupled to a liquid reservoir 110 to form the liquid dispenser 100. The pump unit 10 has a dispensing head 90, which has an applicator tip 96 with a dispensing opening 92. In the state of Fig. 1A und 1B A protective cap is placed on the pump unit 10.

[0065] Fig. 2 Figure 10 shows the liquid dispenser 100 in a cutaway view. It can be seen that the pump unit 10 is inserted into the liquid reservoir 110 through an opening in the bottle body and secured by a closure 94. The design of the Fig. 2 The bottle body is designed to have a tapered neck area 114 such that an immediate radial seal is formed against the outside of the pump unit 10.

[0066] The pump unit 10 has a pump cylinder 30, which forms a housing and is subdivided into a cylinder housing 32 and a housing cover 40. The cylinder housing 32 and the

[0067] Housing covers 40 each have an outwardly facing mounting flange 36, 42, which are pressed together and against the neck of the bottle body by means of the closure 94.

[0068] Through an opening in the housing cover 40, an outlet pipe 60 projects into the cylinder housing 32. A discharge head 90 is connected to this outlet pipe 60 on the outside of the cylinder housing 32, forming a fluid path to a discharge opening 92.

[0069] As intended, the discharge head 90 is pressed down to effect discharge. Pressing down the discharge head 90 also causes the outlet pipe 60 to be pressed down.

[0070] A return spring 70 is provided within the pump cylinder 30. In this embodiment, the corresponding component performs additional functions besides the return spring function, as described below. The return spring 70 has an outwardly projecting bearing element 73 at its upper end 72. In this example, the bearing element 73 is designed as a circumferential bearing ring, but it could also be designed differently, particularly with interruptions. The circumferential design of the bearing element 73 ensures that it forms an effective seal between the housing cover 40 and the cylinder housing 32. Furthermore, the bearing element 73 is under tension by the closure 94, preventing it from slipping out.

[0071] Below the bearing element 73 is the spring section 80, which is designed in the form of a cage spring. This means that the spring section 80 contains a plurality of nodes 82, which are interconnected in a network-like fashion by spring bars 79. The cage spring, which will be described in more detail below with regard to its possible construction, is designed to provide a restoring force by which the pump unit 10 returns to its initial state after manual actuation has ceased.

[0072] For this purpose, a lower end 74 of the return spring 70 is connected to the outlet pipe 60. This connection is achieved by providing the lower end of the outlet pipe 60 with a circumferential stop surface 61, which has a slightly conical shape. Correspondingly, an outer, also slightly conical, stop surface 71 is provided on an inner side of the return spring 70. The stop surfaces 61 and 72 rest against each other and are interlocked by the aforementioned inclination.

[0073] When the discharge head 90 depresses the outlet pipe 60, the return spring 70, and in particular its spring section 80, is stretched as a whole, generating a restoring force that increases with increasing displacement. The return spring 70 is already under tension in its unactuated end position, so that a restoring force is present from the outset upon actuation, enabling it to return to its end position. The return spring 70 has a structure, which will be explained in more detail below, designed to achieve minimal relaxation through the permanently maintained state of tension.

[0074] The extension of the return spring 70 as a whole does not involve the extension of sections of the return spring by the amount of displacement of the outlet pipe. Rather, the extension of the entire return spring 70 in the spring section 80 of the cage spring occurs through bending deformation of parts of the return spring 70, in particular of nodes 82 of the return spring, to which at least two, preferably four, spring bars 79 are attached, which are spread open in pairs. This will be explained further below.

[0075] The pump piston 50 is provided at the lower end of the return spring 70 or at the outlet pipe 60. It has a piston lip 52 that, during operation, bears against a cylindrical wall of the cylinder housing 32, at least intermittently. In the exemplary embodiments, the pump piston 50 is designed as the distal end of the return spring 70, but it could also be designed as a separate part and mechanically connected to the return spring. When the lower end 74 of the return spring 70 is depressed by means of the outlet pipe 60, the pump piston 50 is also depressed, isolating and subsequently reducing the size of the pump chamber 12.

[0076] The cylinder housing 32 has, in addition to a spring section 32B with a larger diameter, a pump chamber section 32A which is adapted to the diameter of the pump piston 50. In the exemplary embodiment, this, together with the pump piston 50, defines the pump chamber 12.

[0077] In the case of the design of the Fig. 2 In the pump chamber area 32A, an internal groove 32C is provided, which means that the pump piston 50 in this area does not yet isolate the pump chamber 12 below the pump piston 50 from the spring area 32B. Therefore, starting from the unactuated end position of the Fig. 2 When the pump piston 50 is depressed, the pump chamber 12 is only isolated once the lower end of the groove 32C has been passed over by the pump piston. Until then, the reduction in size of the pump chamber 12 causes the liquid contained therein to be forced through the groove 32C into the spring area 32B of the cylinder housing 32, from where it can flow back into the liquid reservoir 110 through an outlet opening 32D. With continued movement, the pressure in the pump chamber 12 increases, which, on the one hand, keeps an inlet valve 16 at a liquid inlet 14 closed and, on the other hand, opens an outlet valve 20. The inlet valve 16 is designed as a pressure-dependent opening plate valve, which has a limited-movement valve plate that is forced downwards by overpressure in the pump chamber, thereby closing the liquid inlet 14.The outlet valve 20 is formed by a valve surface 50A on the inside of the pump piston 50 and by a valve component 64, which is inserted into the outlet pipe 60 from below while maintaining a clear cross-section. The outlet valve 20 opens when the pressure in the pump chamber 12 is sufficient to expand the pump piston 50 to such an extent that contact with the conical valve surface 20A of the valve component 64 is lost, allowing liquid to flow from the pump chamber 12 into the liquid outlet 18. The discharge ends at the latest when the actuated end position of the discharge head 90 is reached. Depending on the design, this can occur when the pump piston 50 strikes the lower end of the cylinder housing 32, when another stop on the side of the discharge head 90 and the outlet pipe 60 strikes a stop surface, or when the inlet valve 16 opens towards the end of the actuation, depending on the stroke.

[0078] Towards the end of the actuation, the piston lip 52 abuts the lower end of the pump chamber 12, causing a deformation of the piston lip 52 and thus a forced opening of the outlet valve. This is advantageous because it ensures that even during initial operation of the dispenser, when compressible air is still present in the pump chamber and the pressure-dependent opening of the outlet valve 20 is therefore not pressure-dependent, the outlet valve 20 opens automatically, allowing the air to escape from the pump chamber 12.

[0079] When the force is released from the discharge head 90 upon completion of the actuation, the liquid dispenser 100 returns to its initial position. The return spring 70, or rather its spring section 80, which is under tension as a whole, shortens again and pulls the pump piston 50 upwards. Due to the now closed outlet valve 20, this causes a vacuum in the pump chamber 12, opening the inlet valve 16 and drawing liquid from the liquid reservoir 110. Simultaneously, the outlet pipe 60, and thus the discharge head 90, is also pushed back upwards.

[0080] The Fig. 3A und 3B Figure 1 shows a variety of possible cage springs that can be used as return springs 70. All return springs 70 have in common that they have a flange-like bearing element 73 at an upper end 72, with which the return springs 70 are attached at their upper end to the pump cylinder 30, and that a pump piston 50 is integrally formed with the lower end 74 of the return springs. The different return springs differ with respect to their respective spring range 80. In contrast to these designs, cage springs that are not integrally formed with the pump piston can also be used.

[0081] All spring sections have in common that they are designed like a cage spring and have numerous openings that allow the spring bars 79 to be exposed. These spring bars 79 are connected in groups of several, usually in pairs or groups of four, to the nodes 82 of the cage springs. The spring bars 79 extend at least circumferentially. When the return spring is stretched as a whole, this does not result in individual sections of the spring being stretched by the same distance or to the same extent. Instead, bending deformations occur, primarily in the area of ​​the nodes 82, but also partly in the area of ​​the spring bars 79 themselves.

[0082] When designing the dispenser according to Fig. 2 , but also in the following designs, it is provided that the liquid removed from the liquid reservoir 110 is replaced by incoming air. This air flows, as intended, outside the outlet pipe 60 through the opening 44. In the unactuated position of the Fig. 2 However, the path is blocked by an inner sealing lip 84 of the return spring 70. The vent is only opened upon actuation, and even then only after a delay. This occurs as a stage 62 of the outlet pipe 60 moves past the sealing lip 84 with progressive actuation, thus opening a vent path into the pump cylinder 30, through which the compensating air can pass via the outlet opening 32D into the fluid reservoir.

[0083] The first design of the Fig. 3A The spring has a total of 16 openings 78, 28 spring bars 79, and 16 node pieces 82. The openings 78 each have an oval shape, so that the spring bars 79 already have an inclined orientation relative to the longitudinal direction 2 when the entire spring is unstretched.

[0084] The second design of the Fig. 3A The device has a total of 16 openings 78, 28 spring bars 79, and 16 node pieces 82. However, the openings 78 are not oval-shaped, but rather larger at the sides than in the center. This creates strongly rounded side areas which, when the return spring 70 is deformed, do not cause any notch effect and thus effectively maintain the tension already present in the unactuated end position.

[0085] Even in the third design of the Fig. 3A A total of 16 openings 78, 28 spring bars 79, and 16 node pieces 82 are provided. However, the openings 78 are shaped differently. In their relaxed state, each opening consists of two circular partial openings connected by a slot, in the area of ​​which the spring bars 79 above and below the opening 78 lie directly against each other. These circular partial openings also prevent any notch effect from occurring.

[0086] In the fourth design of the Fig. 3A The design includes 16 openings 78, 28 spring bars 79, and 16 node pieces 82. However, the openings are designed as narrow slots, the opposite edges of which do not touch each other in the relaxed state shown.

[0087] In the initial design of the Fig. 3B The design includes 32 openings 78, 56 spring bars 79, and 32 node pieces 82. A special feature is the three circumferential ring segments, each forming eight node pieces 82 and eight spring bars 79. The ring segments are connected to each other and to the return spring sections below and above the spring section 80 by eight additional spring bars 79 each. Four additional node pieces 82 are provided at each of the return spring sections below and above the spring section.

[0088] The second design of the Fig. 3B It looks similar to the first design. However, since the ring segments are designed differently than in the first design, they are not or hardly deformed when the return spring 70 is stretched and therefore do not store any relevant amount of energy even in the deformed state. In the case of the design of Fig. 3B However, they are still advantageous because they represent stabilizing rings 86, which stabilize the spring area 80 and prevent a generally uneven deformation of the return spring 70.

[0089] The third design of the Fig 3B is basically the first design of the Fig. 3B very similar. The difference here is that instead of three ring segments, four ring segments are provided, so that a total of 40 openings 78 and 72 spring bars 79 and 40 node pieces 82 are provided.

[0090] The fourth design of the Fig. 3B Similar to the second design, this is a modification of the previous variant, but in this case, the ring segments themselves are not subject to any bending deformation occurring during spring extension due to their connection at the top and bottom. The ring segments therefore also serve as stabilizing rings 86.

[0091] Based on the Fig. 4A und 4B The deformation of the spring is explained. The illustrations clarify the principle of deformation, but do not directly represent the actual situation in the installed state, as the deformation differs from the diagram. Fig. 4A There is always already a deformation present.

[0092] Nevertheless, the Fig. 4A und 4B , that the elongation of the return spring 70 and thus of its spring section 80 designed as a cage spring is accompanied by the fact that in the normal orientation of the Fig. 4A und 4B The spring bars are essentially horizontal and deformed by the stretching of the return spring 70, with this deformation primarily occurring in the transition area between connecting node pieces 82 and the respective spring bars 79. Fig. 4B Figure 1 shows the deformed state, with the hatching indicating the main deformation zone where over 80% of the energy applied by strain is stored. This main deformation zone is present at node 82, where the deformation is primarily bending, thus encompassing tensile and compressive stress.

[0093] The tendency for relaxation under this stress has proven to be low. Even with long delivery and storage times, during which the return spring 70 is constantly under tension, a large part of the original return tendency is retained and the unactuated end position is reliably reached after the first manual actuation.

[0094] The openings 78 in the return spring 70 of the Fig. 4A bis 4C In their initial state, they have a bone-like shape. The relatively large rounded edges at each end simultaneously prevent a notch effect and provide an ideal structure for absorbing tensile stress.

[0095] Fig. 4C shows a cross-section of the spring section at the level of the in Fig. 4B The section plane is marked. It can be seen here that the wall cross-section tapers inwards, with the inclined surfaces being angled beyond the radial relative position. It has been shown that such a shape contributes to the stability of the cage spring.

[0096] Fig. 5 , 6 and 7 show alternatives concerning the dispenser or its pump unit 10. Unless otherwise explained, the remaining characteristics of the respective pump units 10 are identical to the characteristics of the pump unit 10 described above. Fig. 2 .

[0097] In the case of the design of the Fig. 5 Instead of the inlet valve 16 designed as a plate valve, a ball valve is provided, i.e. a valve with a deflectable ball body which, in a closed position, isolates the liquid inlet 14 from the pump chamber 12.

[0098] A second difference is that, in this design, the piston lip 52 has no contact whatsoever with the wall of the pump cylinder 30 in the unactuated end position. Only when actuated does the piston lip 52, guided by an insertion ramp, move into the pump chamber 12 and seal it completely against the pump cylinder 30. The fluid that previously escaped through the gap between the piston lip 52 and the pump cylinder 30 flows back into the fluid reservoir 110 through the outlet opening 32D.

[0099] As soon as the pump chamber 12 is isolated and the ball valve is closed, the pressure in the pump chamber rises and the outlet valve 20 opens. After the discharge is complete, the return spring 70 and its cage spring actuate the valve. The ball valve can then open immediately, so that no high vacuum builds up in the pump chamber 12 that the return spring 70 would have to overcome.

[0100] In the design of the Fig. 6 An outlet opening 32E is provided in the wall of the pump cylinder 30 at the level of the pump chamber 12. Only when the piston lip 52 has passed over this outlet opening 32E is the pump chamber 12 isolated and the pressure increase begins, culminating in the discharge of the liquid.

[0101] In this design, the inlet valve 16 is designed as a slotted valve, which opens when there is negative pressure in the pump chamber 12.

[0102] In the design of the Fig. 7A closing extension 13 is provided on the valve component 64. After traversing an empty stroke, the closing extension 13 moves into a metering channel of the inlet valve 16, thus isolating the pump chamber 12. The continued movement pressurizes the liquid contained therein, causing the liquid to be discharged. During the return stroke, a vacuum initially builds up in the pump chamber 12. Only when the closing extension 13 has left the metering channel of the inlet valve 16 can liquid be drawn in under the influence of the previously established vacuum.

Claims

1. Pump unit (10) for a fluid dispenser (100) made of plastic and with the following features: a. the pump unit (10) has a pump cylinder (30) and a pump piston (50), which can be moved relative to the pump cylinder (30) between an unactuated end position and an actuated end position, wherein a pump chamber (12) surrounded by the pump cylinder (30) and the pump piston (50) has its maximum volume in the unactuated end position and its minimum volume in the actuated end position, and b. the pump unit (10) has an inlet valve (16) at a fluid inlet (14) and an outlet valve (20) at a fluid outlet (18), and c. the pump unit (10) has a return spring (70) with which the pump piston (50) is force-actuated in the direction of the unactuated end position, characterized by the following further features: d. the return spring (70) is in the form of a tension spring and arranged in such a way that a cylinder-side end (72) of the return spring (70) and a piston-side end (74) of the return spring (70) are spaced apart from one another in a longitudinal direction when the pump chamber (12) reduces in size, thereby generating or reinforcing a state of tension in the return spring (70), and e. at least sections of the return spring (70) are in the form of a cage spring, which has a wall (77) with a cylindrical or conical basic shape, and f. the wall (77) of the cage spring has a structure formed by perforations (78), with node pieces (82) and spring bars (79) connecting the node pieces (82).

2. Pump unit (10) according to Claim 1 with the following further feature: a. the cage spring has at least four node pieces (82), from each of which at least three spring bars (79) extend to other node pieces or to regions (72, 74) of the return spring (70) adjacent to the cage spring, preferably with the following additional feature: b. the cage spring has at least eight node pieces (82), from each of which at least three spring bars (79) extend to other node pieces or to regions (72, 74) of the return spring (70) adjacent to the cage spring.

3. Pump unit (10) according to Claim 1 or 2 with the following further feature: a. the cage spring has spring bars (79) which are attached in one piece to a common node piece (82) and which are spread open in the course of the spacing of the ends (72, 74) of the return spring (70) and thereby cause a bending deformation in the node piece (82).

4. Pump unit (10) according to Claim 3 with the following further feature: a. in a tensioned state of the return spring (70) when the pump piston (50) is arranged in the actuated end position, a proportion of at least 50% of the stored spring energy of the return spring (70) is stored in the bending deformation of the node pieces (82) and the spring bars (79), preferably with the following additional feature: b. in the tensioned state of the return spring (70), a proportion of at least 80% of the stored spring energy of the return spring (70) is stored in the bending deformation of the node pieces (82) and the spring bars (79).

5. Pump unit (10) according to one of the preceding claims with one of the following further features: a. the cage spring has between 8 and 200 openings (78), preferably between 12 and 100 openings (78), and / or b. the cage spring is made of a polyolefin, preferably of polyethylene.

6. Pump unit (10) according to one of the preceding claims with the following further features: a. the cage spring has openings (78) which are each bounded by four spring bars (79), namely by two upper and two lower spring bars (79), and b. a lower and an upper spring bar (79) each form two spring bars (79), which are connected laterally to the aperture (78) by a common node piece (82), and c. the upper and lower spring bars (79) form spring bars (79) which are each connected to one another in a central position in relation to the aperture via further node pieces (82).

7. Pump unit (10) according to one of the preceding claims with the following further feature: a. the cage spring has a circumferential structure of node pieces (82) and connecting spring bars (79), in which the spring bars (79) are connected at both ends to node pieces (82) and at least some node pieces (82) each carry at least two pairs of spring bars (79), preferably with at least one of the following additional features: b. a plurality of circumferentially distributed node pieces (82) are connected to one another via a circumferential stabilizing ring (86) preferably integrally connected to the node pieces (82), and / or c. at least one node piece, which carries two pairs of spring bars (79), has a cross-section in a plane orthogonal to the longitudinal direction with a shape which tapers or widens in the direction of a central axis of the return spring.

8. Pump unit (10) according to one of the preceding claims with at least one of the following further features: a. the cage spring has perforations (78) which, in lateral regions, form a clear distance in the longitudinal direction (2) which is greater than a central clear distance in the longitudinal direction, and / or b. two spring bars (79) connected in one piece to a node piece (82) are connected by a rounded transition at the node piece (82), preferably with a minimum rounding radius of more than 0.5 mm, in particular with a rounding radius of more than 1.0 mm, and / or c. when the pump cylinder (30) and the pump piston (50) are arranged in the actuated end position, the spring bars (79) at a common node piece (82) enclose an angle which is between 5° and 50° greater than an angle which the spring bars (79) enclose when the pump cylinder (30) and the pump piston (50) are arranged in the unactuated end position.

9. Pump unit (10) according to one of the preceding claims with the following additional features: a. the return spring (70) has, at its lower end, a piston geometry integrally formed on the spring region with a circumferential piston lip (52), and b. the piston lip (52) lies on the inside of the cylindrical pump cylinder (30), preferably with one of the following further features: c. the return spring (70) has a valve surface (20A) of the outlet valve (20) against which a valve section of a valve body bears when the outlet valve (20) is closed, and / or d. the cylindrical pump cylinder (30) has two sections of different diameters, wherein the piston lip rests on the inside of a section with a smaller diameter.

10. Pump unit (10) according to one of the preceding claims with the following further features: a. the pump unit (10) has an outlet pipe (60) which projects into an inner region of the return spring (70), and b. the outlet pipe (60) and the return spring (70) have cooperating stop surfaces (61, 71) by means of which the return spring (70) can be stretched by means of the outlet pipe (60), preferably with the following additional feature: c. the stop surfaces (61, 71) have a conical shape.

11. Pump unit (10) according to one of the preceding claims with the following further features: a. the pump unit (10) has an outlet pipe (60) which is inserted into the return spring (70), and b. the pump unit (10) has a valve component (64) which is inserted into the outlet pipe (60), preferably with at least one of the following additional features: c. the inserted valve component (64) forms the outlet valve (20) together with the return spring (70), and / or d. the inserted valve component (64) forms the inlet valve (16) together with a base of the pump cylinder.

12. Pump unit (10) according to one of the preceding claims with the following further features: a. the return spring (70) has at least one outwardly projecting bearing element (73) at one end (72) to form a cylinder-side spring bearing, preferably in the form of a bearing ring, and b. the return spring (70) is secured to the pump cylinder (30) with respect to a longitudinal direction (2) by means of the bearing element (73), wherein contact surfaces (73A, 33) are provided on the bearing element (73) and on the pump cylinder (30) for this purpose, preferably with at least one of the following additional features: c. the bearing surface (73A) on the bearing element (73) and / or the bearing surface (33) on the pump cylinder (30) are aligned orthogonally to an actuating direction, forming a stepped structure, and / or d. the contact surface (73A) on the bearing element (73) and / or the contact surface (33) on the pump cylinder (30) are provided with a chamfer which counteracts slippage.

13. Pump unit (10) according to one of the preceding claims with the following further feature: a. the pump unit (10) has a cylinder housing (32) and a housing cover (40) to form the pump cylinder (30), preferably with one of the following further features: b. the housing cover (40) and the cylinder housing (32) each have an outwardly projecting installation flange (42, 36), wherein the two installation flanges (42, 36) bear directly against one another, and / or c. the housing cover (40) is provided with an aperture (44) through which an actuating plunger (60) projects, preferably in the form of an outlet pipe (60).

14. Pump unit (10) according to one of the preceding claims with the following further features: a. the inlet valve (16) is designed as a travel-dependent closing inlet valve (16) which, when the pump piston (50) is moved from the unactuated end position in the direction of the actuated end position, is closed only after an empty stroke distance has been covered, or b. the pump unit has an outlet orifice (32D) through which fluid can flow from the pump chamber (12) back into the fluid reservoir (110) and which, when the pump piston (50) is moved from the unactuated end position in the direction of the actuated end position, is closed only after an empty stroke distance has been covered, preferably with the additional feature: b. the empty stroke distance is at least 5%, preferably at least 10%, of the distance between the actuated and the unactuated end position of the pump piston (50).

15. Pump unit (10) according to one of the preceding claims with the following further feature: a. the pump cylinder (30) and the pump piston (50) are matched to one another in such a way that, in the unactuated end position, they do not bear against one another in a circumferentially sealing manner and, during the displacement of the pump piston (50) in the direction of the actuated end position, only come into circumferentially sealing contact with one another after covering an empty stroke distance, preferably with at least one of the following additional features: b. an outflow aperture (32D) is provided in a wall of the pump cylinder (30), through which fluid which flows out of the pump chamber (12) before reaching the circumferentially sealing contact flows back into the fluid reservoir (110), and / or c. the empty stroke distance is at least 5%, preferably at least 10%, of the distance between the actuated and the unactuated end position of the pump piston (50), and / or d. the inlet valve (16) is designed as a pressure-dependent closing inlet valve (16) which opens with respect to the fluid reservoir (110) in the event of negative pressure in the pump chamber (12), wherein the inlet valve (16) is preferably realized either as a plate valve or as a valve with a valve ball, and / or e. an annular gap remains between an inner wall of the pump cylinder (30) and the pump piston (50) in the unactuated end position, or f. the pump piston (50) is in contact with the inner wall of the pump cylinder (30) over a partial section of the circumference in the unactuated end position and is spaced from the inner wall of the pump cylinder (30) in another partial section of the circumference, forming an outflow channel (32C).

16. Pump unit (10) according to one of the preceding claims with the following further feature: a. the pump cylinder (30) has an outflow aperture (32E) in a cylinder wall, wherein this outflow aperture (32E) is arranged such that it is traversed by pump pistons when the pump piston is transferred from the unactuated end position to the actuated end position.

17. Fluid dispenser (100) for dispensing pharmaceutical or cosmetic fluids, having the following features: a. the fluid dispenser (100) has a fluid reservoir (110), and b. the fluid dispenser (100) has at least one discharge opening (92), and c. the fluid dispenser (100) has a pump unit (10) by means of which fluid can be pumped from the fluid reservoir (110) to the discharge opening (92), characterized by the following additional feature: d. the pump unit (10) is designed according to one of the preceding claims, preferably with at least one of the following additional features: e. the fluid reservoir (110) has a volume of less than 100 ml, preferably less than 50 ml, and / or f. the fluid reservoir (110) is filled with a pharmaceutical or cosmetic fluid, and / or g. the fluid dispenser (100) is designed as a spray dispenser or as a dispenser for dispensing a non-atomized jet of fluid or as a drop dispenser.