EP4470676A1 - Pump unit and liquid dispenser comprising such a pump unit - Google Patents

Abstract

Pump unit (10) which has a pump cylinder (30) and a pump piston (50) which is movable relative to the pump cylinder (30) between an unactuated end position and an actuated end position. The pump unit (10) also has an inlet valve (16) on a liquid inlet (14) and an outlet valve (20) on a liquid outlet (18) as well as a return spring (70) by means of which the pump piston (50) is subjected to force in the direction of the unactuated end position. It is proposed that the return spring (70) be designed as 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) is reduced in size, and in the process a stress state is generated or increased in the return spring (70). The return spring (70) is designed at least in sections as a cage spring, which has a wall (77) with a cylindrical or conical basic shape. The wall (77) of the cage spring has a structure formed by openings (78) with node pieces (82) and spring webs (79) connecting the node pieces (82).

Description

FIELD OF APPLICATION AND STATE OF THE ART

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

A generic pump unit is part of a liquid dispenser, for example a liquid dispenser for pharmaceutical liquids or possibly also cosmetic liquids. The pump unit is designed to suck liquid from a liquid reservoir and to apply pressure to it for the purpose of dispensing it through a dispensing opening. The dispensing takes place in particular in the form of a spray jet, but can also take the form of an unatomized jet or in the form of individual drops.

Pump units of this type are usually intended for manual actuation, in particular for actuation in the form of pressing down an actuating button, on which in particular the discharge opening can also be provided.

Pump units of this type are usually provided with a return spring which, after actuation and a usually associated reduction in the volume of a pump chamber, combined with a discharge of the liquid, pushes the pump unit back into its starting position and in doing so moves a pump piston back to its starting position.

In the past, the return spring was usually designed as a metal spring. However, many liquid dispensers now use a plastic spring. This makes recycling easier, as there is no need to separate the metal components from the plastic.

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

The known systems have return springs with parallel single strands or circumferentially closed sleeve bodies that are stretched when the pumping device is activated. It has been shown that this design is problematic because it is difficult to find a material that regarding the required actuation force and the desired return force allows for comfortable use. From the US 2002/043540 A1 It is known to align a sleeve body in such a way that the extension of the return spring is less than the movement path of the pump piston. However, the design described here is quite large and difficult to implement in practice with compact dispensers.

TASK AND SOLUTION

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 which simultaneously ensures the desired functioning of the pump unit and enables easy recycling.

According to the invention, a pump unit for a liquid dispenser and a liquid dispenser with such a pump unit are proposed. The pump unit is described below in particular. However, the embodiments equally relate to a liquid reservoir with such a pump unit.

The pump unit according to the invention has 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 one section, a cylindrical sealing surface in the region of which the pump piston rests against this sealing surface in a circumferentially sealing manner.

A pump chamber surrounded by the pump cylinder and the pump piston has its maximum volume in the non-actuated end position and its minimum volume in the actuated end position. During the actuation-related reduction of the pump chamber volume, liquid is pumped out of the pump chamber in the direction of a discharge opening. During the subsequent return stroke and the associated increase in the pump chamber volume, liquid is sucked into the pump chamber from a liquid reservoir.

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 closed and the inlet valve is open at least in phases, so that liquid is sucked into the pump chamber through the liquid inlet. As will be 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 negative pressure in the pump chamber or depending on the distance.

The pump unit has a return spring, by means of which the pump piston is subjected to force in the direction of the non-actuated end position. This spring acts between the housing or in particular the pump cylinder of the pump unit on the one hand and the pump piston on the other, whereby the return spring can also be mounted on components attached to the pump cylinder and the pump piston instead of on the pump cylinder and the pump piston. In particular, the pump piston itself can also be an integral part of the return spring, as will be explained below.

According to the invention, this return spring is designed in a special way. According to the invention, the return spring is designed as a tension spring and is arranged in such a way that a cylinder-side end and a piston-side end of the return spring are spaced apart from one another in a longitudinal direction when the pump chamber is reduced in size, thereby creating or increasing a state of tension in the return spring. When the pump unit is actuated, the piston is thus spaced apart 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.

The return spring is designed as a cage spring at least in sections. This means that the area of the return spring designed as a cage spring or, if applicable, the return spring designed as a cage spring as a whole has a circumferential wall with a cylindrical or conical basic shape. Openings are provided in this wall which has a structure with node pieces and spring bars connecting the node pieces.

It has been shown that the design of a tension return spring as a cage spring offers considerable advantages. In particular, there is a weaker tendency to relax. In addition, in a cage spring, the elastic elongation is not only caused by material stretching, but to a large extent by bending deformation. This leads to greater flexibility in the selection of the spring material, because materials that would cause too high an actuation force in the case of pure tensile stress, even if they were of appropriate strength, can be considered if the return spring is instead also or predominantly elongated by bending deformation.

The design of the return spring as a tension spring has the advantage that the shape of the spring is defined when tensioned by actuation. With compression springs, however, there is the problem that that they can deviate in a way that is not always easy to predict and can therefore impair the function of the dispenser. The cage spring has proven to be particularly well suited to ensuring a defined positional behavior of the return spring when actuated. The deformation of the return spring can be controlled very precisely by specifically strengthening or weakening node pieces and/or spring bars.

A cage spring usually has node pieces in its wall which, due to the arrangement of the openings, are integrally connected to spring bars with adjacent node pieces or with areas of the return spring adjacent to the cage spring.

The cage spring preferably has at least four node pieces, from which at least three spring bars extend to other node pieces or to areas of the return spring adjacent to the cage spring. In particular, at least eight such node pieces are preferably provided, or even twelve or more such node pieces.

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

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

It has been shown, particularly with such a spring based on bending deformation, that with such node pieces and spring bars there is only a low 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.

The energy applied during actuation does not have to be stored exclusively by the bending deformation in the nodes or spring bars. In addition, 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, Arrangement of the pump piston in the actuated end position a proportion of at least 50% of the spring energy of the return spring is stored in the bending deformation of the node pieces and the spring bars, preferably a proportion of at least 80%.

The wall of the cage spring has spring bars cut free on both sides through openings, with preferably between 8 and 200 openings and particularly preferably between 12 and 100 openings being provided. Preferably, at least three such spring bars are formed by the openings, but particularly between 12 and 72 spring bars.

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 can also be provided that the return spring is made as a 2K part. In such a case, preferably at least the cage spring is made of polyolefin.

The cage spring has a structure of openings and intermediate node pieces and spring bars. When the cage spring is elongated during dispenser operation, an elastic deformation by bending takes place in the node pieces, whereby the bending deformation of the node pieces also includes the bending deformation in the transition sections of the spring bars that immediately adjoin the node pieces. In particular, two spring bars that are connected in one piece to a node piece are connected by a rounded transition on the node piece, preferably with a minimum rounding radius of more than 0.5 mm, in particular more than 1.0 mm. This transition radius is considered to be part of the node piece in the sense of the invention.

The cage spring preferably has openings which are each delimited by four spring bars, namely two upper and two lower spring bars. A lower and an upper spring bar each form two spring bars which are connected to the side of the opening by a node piece. The upper and lower spring bars form spring bars which are each connected to one another in a central position relative to the opening by further node pieces.

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.

The cage spring preferably has a circumferential structure of node pieces and connecting spring bars, in which the spring bars are connected to node pieces at both ends and In particular, preferably at least some node pieces each carry at least two pairs of spring bars. The node pieces are preferably arranged one behind the other in the longitudinal direction in the form of rows, with preferably 4, 6 or 8 rows of node pieces being provided and distributed over the circumference of the cage spring.

At least one of the node pieces, which carry two pairs of spring bars, preferably has a cross-section in a plane orthogonal to the longitudinal direction with a shape that tapers in the direction of a central axis of the return spring. Two lateral flanks of the node piece are therefore not aligned parallel, but are angled radially with respect to the central axis of the cage spring or even beyond the radial alignment. In particular, the cross-section of the node piece can have a triangular cross-sectional area. The opposite alignment with a shape that tapers in the direction away from a central axis or the parallel alignment of the flanks can also be advantageous depending on the specific shape of the cage spring and the conditions in production.

It has been shown that the taper in the direction of the central axis reduces stress peaks and thus reduces the risk of damage to the return spring during operation of the pump unit.

Another special design provides that a plurality of peripherally distributed node pieces are provided, which are connected to one another via a stabilizing ring. In particular, the circumferential stabilizing ring is preferably formed in one piece with the node pieces. The stabilizing ring is preferably connected to the node pieces of the cage spring in such a way that no bending deformation or other relevant deformation takes place in it when the return spring is stretched.

Such a stabilizing ring can be useful in a cage spring to connect node pieces that are arranged on a common geometric plane orthogonal to the longitudinal axis, thus reducing the tendency of the node pieces to deviate outwards or inwards during actuation. Instead, the position of the node pieces relative to one another remains largely unchanged and the energy stored in the return spring is stored primarily via the deformation of the spring bars.

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

A preferred design provides that the cage spring has openings which form a clear distance in the longitudinal direction in lateral areas that is greater than a central clear distance in the longitudinal direction. The clear distance in the longitudinal direction is preferably zero centrally in the non-actuated state of the return spring, which means that the opposing surfaces of the return spring do not rest against one another only in two lateral areas of the opening in the non-actuated state.

The design described is particularly suitable for achieving a high degree of deformation without damaging the return spring. In the lateral areas mentioned, the return spring component is preferably provided with rounded sections in order to prevent the return spring from tearing when actuated.

When the pump cylinder and the pump piston are arranged in the actuated end position, the spring bars on a common node preferably enclose an angle that is between 5° and 50° larger than an angle that the spring bars enclose when the pump cylinder and the pump piston are arranged in the non-actuated end position. Preferably, a straight line that runs through nodes connected by means of a spring bar encloses an angle of less than 10° with a plane orthogonal to the longitudinal direction when the pump unit is in the non-actuated state and an angle of more than 10° when the pump unit is in the actuated state.

The return spring can be connected to the pump piston in various ways. For example, a mechanical coupling is possible, which can be made possible by form-fitting contours on the return spring and a pump piston part.

However, a one-piece design is particularly advantageous, in which the return spring has a piston geometry with a circumferential piston lip that is integrally formed on the return spring at its lower end. This piston lip forms the pump piston and, at least in phases, rests on the inside of the cylindrical pump cylinder during operation. The one-piece design means that there is no need for a positive or non-positive coupling of the pump piston with the return spring, which is sufficiently stable under tensile load.

A component made of just one plastic can be provided as a one-piece component, which includes the piston lip and the spring area with node pieces and spring bars. In addition, a component manufactured using multi-component injection molding is also conceivable in order to provide the component with special material properties in sections. In this case, the cage spring and the piston lip in particular can be made of different materials.

The return spring can also have other functional components, particularly in the one-piece design with a one-piece molded piston lip. 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. In particular, this valve section is preferably designed to expand under the effect of a liquid overpressure and to be lifted off a valve counter surface in order to thereby enable the liquid to be discharged.

Preferably, a design is provided in which the pump unit has an outlet pipe which projects from a discharge side into an inner region of the return spring. The outlet pipe is preferably provided in a fixed position relative to an actuating handle by means of which the pump unit is manually actuated. The coupling between the return spring and the outlet pipe takes place in the inner region of the return spring. For this purpose, the outlet pipe and the return spring preferably have interacting stop surfaces so that the return spring can be stretched by means of the outlet pipe when it is pressed down. The stop surfaces can be aligned orthogonally to a direction of displacement of the outlet pipe. It is particularly advantageous if at least one and preferably both stop surfaces have a conical or otherwise widening shape. The stop surfaces can thus engage with one another. In such a case, the outlet pipe is, as it were, hooked into the stop surface of the return spring.

The formation of an outlet valve can be carried out in particular 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 can in particular be designed as a separate component which can be attached to the outlet pipe and in particular inserted here.

The valve component preferably forms a valve surface of the outlet valve, which, when the outlet valve is closed, rests in the region of a lower end of the return spring and/or on an inner side of the pump piston. If the pressure in the pump chamber is sufficiently high, the return spring or the pump piston is elastically expanded so that the contact is lost and the outlet valve is thereby opened.

The valve component can alternatively or additionally also be part of the inlet valve. For this purpose, it is preferably provided that the liquid inlet is provided in a base of the pump cylinder and that a section of the valve component moves into the liquid inlet when the outlet pipe is pressed down or moves within the liquid inlet and thereby closes the inlet valve. This is particularly useful if a discharge delayed compared to the actuation of the pump unit is desired, as will be explained below.

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 can 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 to form a stepped structure or are provided with a chamfer to prevent the bearing element from sliding off the pump cylinder.

In a preferred embodiment, the design of the pump unit provides that the pump unit has 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, namely a return spring section with a larger diameter to accommodate the cage spring of the return spring and a pump chamber section with a smaller diameter, the diameter of the pump chamber section being adapted to the outer diameter of the pump piston at least in sections to limit the pump chamber. The housing cover is intended to close the pump unit and in particular its return spring section at the top. It can be provided with an opening through which an actuating tappet protrudes, preferably in the form of the outlet pipe already mentioned.

The return spring can be clamped between the cylinder housing and the housing cover. In particular, the housing cover and the cylinder housing each preferably have an outwardly projecting installation flange, with the two installation flanges directly abutting one another. The abutting installation flanges allow the two housing elements of the pump unit, i.e. the The cylinder housing and the housing cover are pressed together and fixed in position so that the cylinder-side spring bearing of the return spring is sufficiently secured.

The outlet valve of the pump unit is preferably a pressure-dependent opening outlet valve, i.e. a valve which opens when a design-specified limit pressure in the pump chamber has been reached.

The inlet valve can also be designed as a pressure-dependent opening valve, which opens when the pressure in the pump chamber has fallen sufficiently compared to the pressure in the liquid reservoir so that a negative pressure prevails in the pump chamber. In a special design, however, the inlet valve is designed as a path-dependent closing inlet valve, which closes in a structurally defined intermediate position after covering an idle stroke when the pump piston is transferred from the non-actuated end position towards the actuated end position. In addition, it can be provided that a closing extension provided for this purpose, which enters a dosing channel to close the inlet valve and seals it, opens this dosing channel again at the opposite end towards the end of the actuation so that the discharge ends abruptly and in a well-defined manner. This also makes it easier to start up the dispenser, since this allows air in the pump chamber or compressed there to escape into the liquid reservoir during start-up.

As an alternative to such a path-dependent closing inlet valve, it can be provided that the pump unit has a closable outflow channel through which liquid can flow from the pump chamber back into the liquid reservoir and which is only closed after an idle stroke has been covered when the pump piston is transferred from the unactuated end position towards the actuated end position.

Both designs, that of the inlet valve that closes after an idle stroke and that of the outlet channel that closes after an idle stroke for the purpose of backflow from the pump chamber into the liquid reservoir, mean that when the pump unit is activated, no discharge takes place initially, since the liquid in the pump chamber is not yet isolated from the liquid reservoir at the start of activation and therefore no pressure can be built up here to open the outlet valve. Only when the idle stroke has been covered is the pump chamber isolated from the liquid reservoir, the pressure in the liquid increases and discharge begins. The idle stroke is at least 5%, preferably at least 10%, of the distance between the activated and the unactivated end position of the pump piston.

The delayed discharge of liquid by the idle stroke is advantageous because it ensures that a uniform amount of liquid can be achieved per actuation, even if the return spring has a length that deviates from the nominal length when not actuated due to relaxation or other aging processes.

One way of implementing an outflow channel of the type described is for the pump cylinder and the pump piston to be coordinated in such a way that they do not form a circumferential seal against each other in the non-actuated end position and that they only come into circumferential sealing contact with each other after an idle stroke has been covered during the displacement of the pump piston in the direction of the actuated end position. Only when the circumferential sealing contact is established can no more liquid escape from the pump chamber into the liquid reservoir and continued actuation causes the liquid to be discharged.

The fact that the pump cylinder and the pump piston are coordinated with one another in such a way that they do not form a circumferential seal against one another in the non-actuated end position can be achieved by the pump piston not being in contact with the pump cylinder in the non-actuated end position, so that an annular gap remains between an inner wall of the pump cylinder and the pump piston. Alternatively, a design is possible in which the pump piston in the non-actuated end position rests against the inner wall of the pump cylinder over a partial section of the circumference and is spaced from the inner wall of the pump cylinder in another partial section of the circumference, forming an outflow channel.

In both cases, the liquid can escape from the pump chamber at the pump piston at the beginning of an actuation and then flow back into the liquid reservoir through an outflow opening in the pump cylinder.

Another possible design provides that the pump cylinder has an outflow opening in a cylinder wall of the pump cylinder, whereby this outflow opening is arranged in such a way that it is passed over by the pump piston when the pump piston is transferred from the non-actuated end position to the actuated end position. Up to this point, liquid can flow from the pump chamber back into the liquid reservoir. As soon as the pump piston has passed over the outflow opening, the liquid in the pump chamber is pressurized and thus discharged.

Although liquid can be pressed back from the pump chamber into the liquid reservoir at a defined intermediate position via a path-dependent inlet valve as well as via the aforementioned outflow channel, the outflow channel is preferred because it makes it possible to avoid a negative pressure in the pump chamber during the return stroke. Such a negative pressure is worth avoiding because it makes it necessary to design the return spring to be sufficiently strong to overcome the negative pressure. The use of an additional outflow channel eliminates this need. Particularly in the case of a pump unit with an outflow channel, it is therefore considered advantageous if the inlet valve is designed as a pressure-dependent closing inlet valve which opens opposite the liquid reservoir when there is excess pressure in the pump chamber. Such a pressure-dependent closing and opening inlet valve allows liquid to be sucked into the pump chamber almost immediately at the start of the return stroke. Preferred designs of the inlet valve are above all plate valves or valves with a valve ball.

The pump units described preferably consist entirely of plastic, in particular exclusively of plastics that can be processed in a common recycling stream. However, the pump unit can also have 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%.

A liquid dispenser according to the invention has a pump unit according to the invention. In particular, such a liquid dispenser preferably has a liquid reservoir made of plastic. This 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.

The liquid reservoir preferably has a total volume of less than 100 ml, in particular less than 50 ml. In the ready-to-sell state, the liquid reservoir is preferably filled with a pharmaceutical or cosmetic liquid.

BRIEF DESCRIPTION OF THE DRAWINGS

• Fig. 1A und 1B zeigen einen erfindungsgemäßen Flüssigkeitsspender sowie eine Pumpeneinheit hierfür in ungeschnittener Darstellung.
• Fig. 2 zeigt eine erste Variante einer erfindungsgemäßen Pumpeneinheit in einer geschnittenen Darstellung.
• Fig. 3A und 3B zeigen verschiedene Varianten von Rückstellfedern für die Pumpeneinheit der Fig. 2, 5 und 6.
• Fig. 4A bis 4C verdeutlicht die Verformung einer Rückstellfeder der erfindungsgemäßen Pumpeneinheit bei Betätigung.
• Fig. 5, 6 und 7 zeigen eine zweite, dritte und vierte Variante einer erfindungsgemäßen Pumpeneinheit in geschnittener Darstellung.

Further advantages and aspects of the invention emerge 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 and 1B show a liquid dispenser according to the invention and a pump unit therefor in an uncut representation.
• Fig. 2 shows a first variant of a pump unit according to the invention in a sectional view.
• Fig. 3A and 3B show different variants of return springs for the pump unit of the Fig. 2 , 5 and 6 .
• Fig. 4A to 4C illustrates the deformation of a return spring of the pump unit according to the invention during actuation.
• Fig. 5 , 6 and 7 show a second, third and fourth variant of a pump unit according to the invention in a sectional view.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Fig. 1A and 1B show 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 discharge head 90, which has an applicator tip 96 with a discharge opening 92. In the state of Fig. 1A and 1B A protective cap is placed on the pump unit 10.

Fig. 2 shows the liquid dispenser 100 in a sectional view. It can be seen that the pump unit 10 is inserted through an opening in the bottle body of the liquid reservoir 110 and is secured by means of a closure 94. In the design of the Fig. 2 It is provided that the bottle body has a tapered neck region 114 such that a direct radial seal to the outside of the pump unit 10 is formed.

The pump unit 10 has a pump cylinder 30, which forms a housing and is divided into a cylinder housing 32 and a housing cover 40. The cylinder housing 32 and the housing cover 40 each have an outward-facing installation flange 36, 42, which are pressed against each other and against the neck of the bottle body by means of the closure 94.

An outlet pipe 60 projects into the cylinder housing 32 through an opening in the housing cover 40. A discharge head 90 is connected to this outlet pipe 60 on the outside of the cylinder housing 32 and forms a liquid path up to a discharge opening 92.

As intended, the discharge head 90 is depressed to effect discharge. Depressing the discharge head 90 also causes the outlet pipe 60 to be depressed.

A return spring 70 is provided within the pump cylinder 30, whereby the corresponding component in this embodiment takes on additional functions in addition to the return spring function, as described below. The return spring 70 has an outwardly projecting bearing element 73 at its upper end 72, which in this case is designed in the form of a circumferential bearing ring, but could also be designed differently and in particular with interruptions. The circumferential design of the bearing element 73 means that it represents an effective seal between the housing cover 40 and the cylinder housing 32. The closure 94 also puts the bearing element 73 under tension, so that there is no risk of it slipping out.

Below the bearing element 73 is the spring area 80, which is designed in the manner of a cage spring. This means that a plurality of node pieces 82 are provided in the spring area 80, which are connected to one another in a network-like manner by spring bars 79. The cage spring, which is described in more detail below with regard to its possible structure, is designed to provide a restoring force by means of which the pump unit 10 returns to its initial state after the end of the manual actuation of the pump unit 10.

For this purpose, a lower end 74 of the return spring 70 is connected to the outlet pipe 60. The connection is created by the lower end of the outlet pipe 60 being provided with a circumferential stop surface 61 which has a slightly conical shape. Correspondingly, an external and also slightly conical stop surface 71 is provided on an inner side of the return spring 70. The stop surfaces 61, 71 lie against one another and are hooked together as it were by the aforementioned inclination.

If the outlet pipe 60 is pressed down via the discharge head 90, the return spring 70, in particular its spring area 80, is stretched as a whole and a return force is generated that becomes stronger with increasing displacement. The return spring 70 is already under tensile stress in its non-actuated end position, so that when actuated, a return force is present from the start, which enables the return to the end position. The return spring 70 has a structure explained in more detail below, which is designed to achieve a low relaxation through the permanently existing tensile stress state.

The stretching of the return spring 70 as a whole does not involve partial sections of the return spring being stretched by the amount of displacement of the outlet pipe. Rather, the stretching of the entire return spring 70 in the spring region 80 of the cage spring takes place with bending deformation of parts of the return spring 70, in particular of node pieces 82 of the return spring, to which at least two, preferably four, spring webs 79 are attached, which are spread apart in pairs. This will be explained further below.

The pump piston 50 is provided at the lower end of the return spring 70 or at the outlet pipe 60 and has a piston lip 52 which, during operation, rests at least in phases against a cylindrical wall of the cylinder housing 32. In the case of the exemplary embodiments, the pump piston 50 is designed as the distal end of the return spring 70, but could also be designed as a separate part and be mechanically connected to the return spring. If the lower end 74 of the return spring 70 is pressed down by means of the outlet pipe 60, the pump piston 50 is also pressed down and the pump chamber 12 delimited thereby is isolated and subsequently reduced in size.

In addition to a spring region 32B with a larger diameter, the cylinder housing 32 has a pump chamber region 32A that is adapted to the diameter of the pump piston 50. In the exemplary embodiment, this delimits the pump chamber 12 together with the pump piston 50.

In the case of the design of the Fig. 2 In the pump chamber area 32A, an inner 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. Thus, starting from the non-actuated end position of the Fig. 2 the pump piston 50 is depressed, this only leads to an isolation of the pump chamber 12 when the lower end of the groove 32C is passed over by the pump piston. Until then, the reduction in the size of the pump chamber 12 leads to the liquid contained therein being pressed through the groove 32C into the spring area 32B of the cylinder housing 32, from where it can pass back into the liquid reservoir 110 through an outflow opening 32D.

As the movement continues, the pressure in the pump chamber 12 is increased, which on the one hand keeps an inlet valve 16 on 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 plate valve, which has a limitedly movable valve plate, which is pressed downwards by excess pressure in the pump chamber and thereby closes 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 and 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 and liquid can 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 may be the case 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 is opened in a path-dependent manner towards the end of the actuation.

Towards the end of the actuation, the piston lip 52 hits the lower end of the pump chamber 12, causing the piston lip 52 to deform and thus forcing the outlet valve to open. This is advantageous because it also causes the outlet valve 20 to open automatically when the dispenser is started up, when there is still compressible air in the pump chamber and the outlet valve 20 does not open depending on the pressure, and the air can therefore escape from the pump chamber 12.

If the force applied to the discharge head 90 is removed at the end of the actuation, the liquid dispenser 100 returns to its starting position. The return spring 70 or its spring area 80, which is under tension as a whole, shortens again and pulls the pump piston 50 upwards. Due to the outlet valve 20 now being closed, this causes a negative pressure in the pump chamber 12, the inlet valve 16 opens and liquid is sucked in from the liquid reservoir 110. At the same time, the outlet pipe 60 and thus the discharge head 90 are also pushed back upwards.

The Fig. 3A and 3B show 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 an integrally formed pump piston 50 is provided at the lower end 74 of the return springs. The various return springs differ in terms of their respective spring area 80. Deviating from these designs, cage springs can also be used that are not formed integrally with the pump piston.

What all spring areas have in common is that they are designed in the form of a cage spring and have a large number of openings that allow spring bars 79 to be cut free. These spring bars 79 are connected in several, usually two or four at a time, to node pieces 82 of the cage springs. The spring bars 79 extend at least in the circumferential direction. If 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 node pieces 82, but also partly in the area of the spring bars 79 themselves.

When designing the dispenser according to Fig. 2 , but also in the following designs, it is provided that liquid removed from the liquid reservoir 110 is replaced by incoming air. This air flows as intended on the outside of the outlet pipe 60 through the opening 44. In the unactuated position of the Fig. 2 However, the path is blocked by an internal sealing lip 84 of the return spring 70. The ventilation is only opened when actuated and then only with a delay. This is done by a step 62 of the outlet pipe 60 moving past the sealing lip 84 as actuation progresses, so that a ventilation path is opened in the pump cylinder 30, through which the compensating air can reach the liquid reservoir by means of the outlet opening 32D.

The first design of the Fig. 3A has a total of 16 openings 78 and 28 spring bars 79 as well as 16 node pieces 82. The openings 78 each have an oval shape, so that the spring bars 79 already have an inclined orientation in relation to the longitudinal direction 2 in the unstretched state of the entire spring.

The second design of the Fig. 3A has a total of 16 openings 78, 28 spring bars 79 and 16 node pieces 82. The openings 78 are not oval in shape, but are larger in the side areas than in the middle. This creates strongly rounded side areas that do not cause any notch effect when the return spring 70 is deformed and can therefore maintain the tension already present in the non-actuated end position.

The third design of the Fig. 3A A total of 16 openings 78, 28 spring bars 79 and 16 nodes 82 are provided. Here, however, the openings 78 are again shaped differently. In the relaxed state, they each consist of two circular partial openings that are connected by a slot, in the area of which the spring bars 79 above and below the opening 78 lie directly against each other. The aforementioned circular partial openings also mean that no notch effect occurs.

In the fourth design of the Fig. 3A 16 openings 78, 28 spring bars 79 and 16 node pieces 82 are provided. Here, however, the openings are designed in the form of narrow slots, the opposite edges of which do not lie against one another in the relaxed state shown.

When first designing the Fig. 3B 32 openings 78, 56 spring bars 79 and 32 node pieces 82 are provided. A special feature here is a total of three circumferential ring segments, each of which forms eight node pieces 82 and eight spring bars 79. The ring segments are connected to each other and to the return spring areas below and above the spring area 80 via eight further spring bars 79 each. Four further node pieces 82 are provided on the return spring areas below and above the spring area.

The second design of the Fig. 3B 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. The ring segments are in the case of the design of the Fig. 3B However, they are nevertheless advantageous since they represent stabilizing rings 86, by means of which the spring region 80 is otherwise stabilized and a circumferentially non-uniform deformation of the return spring 70 is avoided.

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.

The fourth design of the Fig. 3B is similar to the second design, a modification of the previous variant, but in this case the ring segments are not subject to any bending deformation that occurs when the spring is stretched due to the connection at the top and bottom. The ring segments therefore also serve as stabilization rings 86 here.

Based on the Fig. 4A and 4B the deformation of the spring is explained. The illustrations illustrate the principle of deformation, but do not directly represent the real situation in the installed state, since in the installed state, Fig. 4A there is always already a deformation.

Nevertheless, the Fig. 4A and 4B that the elongation of the return spring 70 and thus of its spring area 80 designed as a cage spring is accompanied by the fact that in the normal orientation of the Fig. 4A and 4B essentially horizontal spring bars are deformed by the extension of the return spring 70, wherein this deformation occurs primarily in the transition region between connecting node pieces 82 and the respective spring bars 79. Fig. 4B shows the deformed state, with the hatching indicating the main deformation region in which over 80% of the energy applied by stretching is stored. This main deformation region is present at the node pieces 82, with the deformation being mainly a bending deformation, i.e. comprising tensile stress and compressive stress.

The tendency to relax under this stress has proven to be low. Even during long delivery and storage periods in which the return spring 70 is permanently under tension, a large part of the original tendency to return is retained and the non-actuated end position is reliably reached after the first manual actuation.

The openings 78 in the return spring 70 of the Fig. 4A to 4C have a bone shape in their initial state. The relatively large roundings at the respective ends prevent a notch effect and provide an ideal structure for absorbing the tensile stress.

Fig. 4C shows a cross section of the spring section at the level of Fig. 4B marked cutting plane. It can be seen that the wall cross-section tapers inwards, with the inclined surfaces being inclined beyond the radial relative position. It has been proven that such a shape is beneficial to the stability of the cage spring.

Fig. 5 , 6 and 7 show alternatives concerning the dispenser or its pump unit 10. Unless otherwise stated, the other features of the respective pump units 10 are identical to the features of the pump unit 10 of the Fig. 2 .

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 spherical body which, in a closed position, isolates the liquid inlet 14 from the pump chamber 12.

A second difference is that in this design the piston lip 52 has no contact with the wall of the pump cylinder 30 in the non-actuated end position. Only when actuated does the piston lip 52 run into the pump chamber 12 guided by an insertion bevel and This closes all the way around the pump cylinder 30. The liquid that previously escaped through the gap between the piston lip 52 and the pump cylinder 30 returns to the liquid reservoir 110 through the outflow opening 32D.

As soon as the pump chamber 12 is isolated and the ball valve is closed, the pressure in the pump chamber increases and the outlet valve 20 opens. After the discharge has ended, the return takes place under the action of the return spring 70 and its cage spring. The ball valve can open immediately so that no high negative pressure is created in the pump chamber 12, which the return spring 70 has to overcome.

When designing the Fig. 6 an outflow 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 outflow opening 32E is the pump chamber 12 isolated and the pressure increase begins and results in the discharge of liquid.

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

When designing the Fig. 7 a closing extension 13 is provided on the valve component 64. The closing extension 13 moves into a metering channel of the inlet valve 16 after covering an idle stroke and thus isolates the pump chamber 12 so that the continued movement puts the liquid in it under pressure and causes the liquid to be discharged. During the return stroke, a negative pressure initially builds up in the pump chamber 12. Only when the closing extension 13 has left the metering channel of the inlet valve 16 again can liquid be sucked in under the effect of the previously built-up negative pressure.

Claims (17)

Pump unit (10) for a liquid dispenser (100) made of plastic with the following features: a. the pump unit (10) has a pump cylinder (30) and a pump piston (50) which is movable 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 liquid inlet (14) and an outlet valve (20) at a liquid outlet (18), and c. the pump unit (10) has a return spring (70) by means of which the pump piston (50) is actuated in the direction of the unactuated end position, characterized by the following additional features: d. the return spring (70) is designed as a tension spring and arranged such 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) is reduced in size and a tension state is generated or increased in the return spring (70), and e. the return spring (70) is designed at least in sections as a cage spring having a wall (77) with a cylindrical or conical basic shape, and f. the wall (77) of the cage spring has a structure formed by openings (78) with node pieces (82) and spring bars (79) connecting the node pieces (82). Pump unit (10) according to claim 1 with the following further feature: a. the cage spring has at least four node pieces (82), from which at least three spring webs (79) extend to other node pieces or to areas (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 which at least three spring webs (79) extend to other node pieces or to areas (72, 74) of the return spring (70) adjacent to the cage spring. Pump unit (10) according to claim 1 or 2 with the following further feature: a. the cage spring has spring bars (79) which are integrally attached to a common node piece (82) and which are spread apart as the ends (72, 74) of the return spring (70) are spaced apart, thereby causing a bending deformation in the node piece (82). 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 webs (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). 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 polyethylene. 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 delimited by four spring bars (79), namely 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 opening (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 relative to the opening via further node pieces (82). 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) which is 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 that tapers or widens in the direction of a central axis of the return spring. Pump unit (10) according to one of the preceding claims with at least one of the following further features: a. the cage spring has openings (78) which form a clear distance in the longitudinal direction (2) in side areas 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 on 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. the spring bars (79) on a common node piece (82) enclose an angle when the pump cylinder (30) and the pump piston (50) are arranged in the actuated end position 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. 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 area with a circumferential piston lip (52), and b. the piston lip (52) rests on the inside of the cylindrical pump cylinder (30), preferably with one of the following additional 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 rests when the outlet valve (20) is closed, and/or d. the cylindrical pump cylinder (30) has two sections of different diameters, with the piston lip resting on the inside in a section with a smaller diameter. 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. 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) together with the return spring (70) forms the outlet valve (20), and/or d. the inserted valve component (64) together with a bottom of the pump cylinder forms the inlet valve (16). 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), preferably in the form of a bearing ring, at one end (72) to form a cylinder-side spring bearing, and b. the return spring (70) is secured to the pump cylinder (30) in relation to a longitudinal direction (2) by means of the bearing element (73), whereby 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 contact surface (73A) on the bearing element (73) and/or the contact surface (33) on the pump cylinder (30) are aligned orthogonally to an actuating direction to form 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 slipping. 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 additional features: b. the housing cover (40) and the cylinder housing (32) each have an outwardly projecting mounting flange (42, 36), the two mounting flanges (42, 36) being in direct contact with one another, and/or c. the housing cover (40) is provided with an opening (44) through which an actuating plunger (60) projects, preferably in the form of an outlet pipe (60). Pump unit (10) according to one of the preceding claims with the following further features: a. the inlet valve (16) is designed as a path-dependent closing inlet valve (16) which is closed only after an idle stroke has been covered when the pump piston (50) is transferred from the unactuated end position towards the actuated end position, or b. the pump unit has an outflow opening (32D) through which liquid can flow from the pump chamber (12) back into the liquid reservoir (110) and which is closed only after an idle stroke has been covered when the pump piston (50) is transferred from the unactuated end position towards the actuated end position, preferably with the additional feature: b. the idle stroke is at least 5%, preferably at least 10%, of the distance between the actuated and the unactuated end position of the pump piston (50). 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 coordinated with one another in such a way that they do not make circumferential sealing contact with one another in the non-actuated end position and, during the displacement of the pump piston (50) in the direction of the actuated end position, they only come into circumferential sealing contact with one another after covering an idle stroke, preferably with at least one of the following additional features: b. an outflow opening (32D) is provided in a wall of the pump cylinder (30), through which liquid which flows out of the pump chamber (12) before reaching the circumferential sealing contact returns to the liquid reservoir (110), and/or c. the idle stroke is at least 5%, preferably at least 10%, of the distance between the actuated and the non-actuated 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 in the event of a negative pressure in the pump chamber (12) relative to the liquid reservoir (110), wherein the inlet valve (16) is preferably implemented 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 non-actuated end position, or f. the pump piston (50) rests against 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 to form an outflow channel (32C). Pump unit (10) according to one of the preceding claims with the following further feature: a. the pump cylinder (30) has an outflow opening (32E) in a cylinder wall, wherein this outflow opening (32E) is arranged such that it is passed over by the pump piston when the pump piston is transferred from the unactuated end position to the actuated end position. Liquid dispenser (100) for dispensing pharmaceutical or cosmetic liquids having the following features: a. the liquid dispenser (100) has a liquid reservoir (110), and a. the liquid dispenser (100) has at least one discharge opening (92), and a. the liquid dispenser (100) has a pump unit (10) by means of which liquid can be pumped from the liquid 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 liquid reservoir (110) has a volume of less than 100 ml, preferably less than 50 ml, and/or f. the liquid reservoir (110) is filled with a pharmaceutical or cosmetic liquid, and/or g. the liquid dispenser (100) is designed as a spray dispenser or as a dispenser for dispensing an unatomized liquid jet or as a drop dispenser.

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