Valve with one flow direction

Abstract

The invention relates to a valve (1) with one flow direction. The valve comprises a first part (3), a second part (2), and a valve ball (4). Each of the two parts (2, 3) has a valve port (210, 310), a connection area (290, 390), and a flow-through connection (211, 311) located between the valve port (210, 310) and the connection area (290, 390). The valve port (210, 310) is configured to allow the valve (1) to be connected to other components. The first part (3) and the second part (2) can be connected to each other in the connection area. Both parts (2, 3) are configured to form a valve chamber (5) located between the two flow-through connections (211, 311).The valve port (210), which is arranged downstream of the valve chamber (5) in the flow direction, forms a valve outlet (21), and the valve port (310), which is arranged upstream of the valve chamber (5) in the flow direction, forms a valve inlet (31). The valve ball (4) is arranged in the valve chamber (5) and blocks the flow through the valve chamber (5) when flow is against the flow direction. The invention is characterized in that the valve chamber (5) and the valve ball (4) are designed such that the valve ball (4) is freely movable in all three spatial planes within the valve chamber (5) and is not guided by a wall bounding the valve chamber (5).

Description

The invention relates to a valve having a flow direction, in particular for the field of liquid chromatography.Chromatography is a separation method in which a substance mixture to be investigated is separated with the aid of a stationary and a mobile phase. In liquid chromatography, the mobile phase is a liquid with which the substance mixture is moved through the stationary stationary phase. The substance mixture is separated into individual constituents and subsequently analyzed. In order to pass the mixture of substances through the stationary phase, pressures in the range of up to 3000 bar are achieved in liquid chromatography. Accordingly, the load on fluidic components is high, so that valves in particular are particularly prone to failure during operation.It is an object of the invention to provide an improved and reliable valve for liquid chromatography which is particularly suitable for use at very high pressures.This object is achieved by a valve having the features of claim 1. Embodiments of the invention are set forth in the dependent claims.The invention then contemplates a valve having a flow direction. The valve includes a first part, a second part, and a valve ball. The two parts each have a valve connection, a connecting region and a fluidic connection, which is respectively arranged between the connection and the connecting region. The valve connection of the two parts is in each case designed such that the valve can be connected to further components. In the respective connection region, the first part and the second part can be connected to one another. Both parts are designed together to form a valve chamber which is formed between the two fluidic connections.The valve connection of one of the two parts, which is arranged behind the valve chamber in the flow direction, thereby forms a valve outlet and the other valve connection, which is arranged in front of the valve chamber in the flow direction, forms a valve inlet. The valve ball is arranged in the valve chamber and, in the case of a flow counter to the flow direction, blocks the flow through the valve chamber by closing one of the fluidic connections.The invention is distinguished in that the valve ball can move freely in all three spatial planes in the valve chamber and is not guided through a wall delimiting the valve chamber.The invention is distinguished by a simplified construction in which the susceptibility of the valve to errors is simultaneously reduced. The invention is thus based on the idea of not restricting the valve ball in its movement as much as possible and of omitting a guidance of the ball, in particular a guidance in the axial direction. An axial direction is to be understood as a direction along the flow direction. The valve ball thus has a clearance in all three spatial directions which prevents the ball from being caught or stuck on an inner wall of the valve chamber. Thus, in the presence of a guidance of the valve ball by the wall of the valve chamber, it is possible for the valve ball to hook onto an inner wall of the valve chamber, for example if manufacturing parameters have not been exactly observed or a particle is located in the region of the guidance in an unfavorable manner.The interlocking can clamp the ball, so that the valve mechanism is prevented. It is also possible here for the ball to deform parts of the inner wall, for example when releasing from a hooked position, with the result that the ball can move less easily through the guide and the valve mechanism is hindered. Deformations can also occur as a result of particular forces, for example during improper assembly or installation of the valve in an assembly.The valve can furthermore be preassembled in a simple manner by inserting the ball into the intermediate space and subsequently connecting the first and the second, for example by means of a screw connection, to one another in a simple manner. Due to the small number of components and the clearance of the valve ball, the possibility of damage to the valve already in the preassembly is minimized. The uncomplicated construction can also allow the valve to be designed such that it is disassembled and reassembled, for example, for maintenance.As a result, the valve is viewed in each assembled state in which the first part and the second part are connected to each other and the valve ball is disposed in the valve chamber. Accordingly, the terms valve ball and ball, valve outlet and outlet and valve chamber and chamber are each used interchangeably.In one embodiment variant, the first and the second part can be sealed against one another via an acute seal. One of the two parts comprises a flat base surface and the other part a pointed sealing edge, wherein the seal is configured such that the pointed sealing edge is pressed against the flat base surface.The tip seal ensures tightness even at high pressures of up to 3000 bar typical for liquid chromatography. The tip seal is based on the principle that instead of a flat seal with a relatively large sealing surface, the sealing surface is kept as low as possible. For this purpose, the sealing surface is formed only by the contact of the tip of the pointed sealing edge on the flat base surface. According to the physical principle according to which the following applies: Pressure= Force / surface area, the surface area can thus be minimized, so that the required force for the sealing effect is also reduced. As a result, the first and the second part can even be connected to one another manually, for example by means of a hand-proof screw connection, and nevertheless be sufficiently tight.It can be provided here that the tip seal has exclusively metallic elements, i.e. explicitly does not comprise any plastic parts, so that the component is particularly little susceptible to wear.The pointed sealing edge comprises two limbs which are pointed in cross section and have an angle in the range from 20° to 45°, in particular an angle of 29° to 31°. The angle is selected depending on the material used and the pressures present in the valve.In this case, it can be provided that an outer leg of the sealing edge facing away from the fluid is formed parallel to the flow direction of the fluid. When the sealing edge is pressed against the base surface, it can be provided that the sealing edge deforms in a controlled manner. Such a configuration of the outer leg ensures that when the sealing edge is pressed against the base surface, the tip of the sealing edge is minimally deformed outwards. The controlled deformation allows the sealing pair to adapt optimally with respect to one another, so that a particularly high sealing effect is achieved.In a further embodiment of the invention, at least one of the two valve connections comprises a further outer sealing edge for sealing with respect to a connected component, wherein the outer sealing edge comprises two legs which taper in cross section. The pointed sealing edge can form together with a flat sealing surface of a connected component a pointed seal corresponding to the principle explained above.The angle between the legs of the outer sealing edge can be in a range of 40° to 50°, in particular in a range of 44° to 46°.In a variant of the invention, it is provided that the fluidic connection between the valve chamber and the valve outlet has a plurality of outlet channels. By means of a plurality of outlet ducts, an improved flow can be achieved in connection with the Reynolds number present in the flow. In particular, the flow resistance can be reduced by the plurality of flow channels. During valve operation, this has the consequence that the valve ball releases more quickly from a blocking position and / or moves into it with changing flow conditions. This has the overall consequence that the valve can react more quickly and sensitively to changed flow and / or pressure conditions.In particular, it can be provided that the fluidic connection between the valve chamber and the valve outlet has four parallel outlet channels.In principle, it can also be provided in this sense to provide a plurality of inlet channels.In a further embodiment variant, the material of the valve ball is harder in terms of a greater penetration hardness (measured according to common methods such as, for example, according to Vickers) compared to the material of the first and second parts.It can be provided, for example, that the first part and the second part consist of metal, in particular of a stainless steel alloy or titanium alloy. A stainless steel titanium alloy can be provided, for example.For the valve ball, it can be provided, for example, that it consists of sapphire, in particular rubin. Sapphire is characterized by a particularly high hardness with a simultaneously comparatively low density. It can be provided that the valve ball is highly polished in order to provide a particularly smooth surface.It can be provided that at the transition between the fluidic connection, which comes from the inlet and is formed between the inlet and the valve chamber, and the valve chamber, a curved sealing surface corresponding to the valve ball is formed. To block a flow counter to the flow direction, the ball is seated on the sealing surface and thus prevents the opposite flow in the direction of the valve inlet. For a particularly good sealing, a curved sealing surface corresponding to the ball is formed at the transition.The curved sealing surface can be formed by building up a pressure in the valve chamber directed counter to the flow direction, so that the valve ball is pressed in the direction of the inlet and not only closes the inlet, but deforms material at an edge between the valve chamber and the inlet. In this sense, the valve ball pushes material aside and forms the curved sealing surface. The curved sealing surface enables an improved, tight closing of the valve to be achieved.In one exemplary embodiment, it is provided that the valve does not contain elements which consist of polymers.In a further exemplary embodiment, the first part and the second part are formed integrally. Accordingly, no extra components for forming the valve chamber, such as a ceramic ball cage or special sealing elements for the valve, are provided.In this case, it can be provided in particular that the valve comprises exclusively the first part, the second part and the valve ball. The overall small number of components facilitates the assembly and production of the valve and reduces the probability of a faulty component.In a further embodiment of the invention, the first and the second part are screwed to one another. For this purpose, the connecting region of the first part and the connecting region of the second part have a thread, with which both parts are screwed to one another. It can be provided that the valve is disassembled, for example, for maintenance or fault finding, by loosening the screw connection. In this case, it can additionally be provided that the valve is screwed together again subsequently and used further.In one exemplary embodiment, it is provided that the valve ball has a diameter in the range from 1.5 mm to 2.0 mm, in particular in the range from 1.745 mm to 1.755 mm.In a further exemplary embodiment of the invention, the valve ball has at least one movement clearance of 0.1 mm in a direction which is transverse to the throughflow direction. Accordingly, the valve ball can move in the valve chamber in a direction that is transverse to the flow direction at least in a range of 0.1 mm in each case without touching a wall of the valve chamber in the process. Said range of movement can also be at least 0.2 mm.It is noted that in the case where the ball blocks against reverse flow, it seats firmly in a blocking position on the inlet to block flow. However, in this case, the ball is held in the position by the pressure conditions present in the valve chamber and the configuration of the inlet, and not by a laterally delimiting wall of the valve chamber.The invention is explained in more detail below with reference to the figures of the drawing on the basis of an exemplary embodiment. The following are shown: FIG. 1 shows a valve with only one flow direction for liquid chromatography in a lateral sectional view, which comprises a first part, a second part and a valve ball; FIGS. 2, 3 show a valve corresponding to FIG. 1, which is shown in FIG. 2 in a side view and in FIG. 3 in a plan view; FIGS. 4, 5 are perspective views of the valve of FIGS. 1 to 3, the outlet being shown in FIG. 4 and the inlet being shown in FIG. 5 ; and FIG. 6 is a diagram of an assembly in a pump head having a piston and two valves corresponding to the valve of the previous figures.FIG. 1 shows a sectional view of a valve 1 for liquid chromatography, in which a liquid can flow through the valve 1 only in a predetermined flow direction.The valve comprises a first part 3, a second part 2 and a valve ball 4. The flow defines an axial direction corresponding to the arrows.Both parts 2, 3 have a connecting region 290, 390 each with a thread 29, 39, via which the two parts 2, 3 are screwed to one another. Between the two parts 2, 3 a valve chamber 5 for the valve ball 4 is formed. The first part 3 has a blind bore 30 with the thread 39 on one side. The bottom of the bore at the end of the blind bore 30 is formed by a flat base surface 36 which defines the valve chamber 5.The first part 3 has a valve inlet 31 and an inlet duct 311, through which the fluid flows into the valve chamber 5. The inlet channel 311 terminates in the flat base surface 36; accordingly, the second part 2 has a valve outlet 21 and a plurality of outlet channels 211, through which the fluid flows out of the valve chamber 5. The inlet 31 and the outlet 21 form valve connections 201, 310, at which the valve 1 can be connected to further components.The valve mechanism is based on the principle that, in the case of a flow in the flow direction, the fluid can flow around the ball 4 in the valve chamber 5 and then flows out of the valve 1 through the outlet ducts 211. In the case of an opposite flow, on the other hand, the ball 4 is pushed against the inlet duct 311 and blocks or closes the transition from the valve chamber 5 into the inlet duct 311, with the result that the throughflow is prevented. FIG. 1 shows the valve ball 4 in such a blocking position.In the example shown, the valve 1 comprises four parallel outlet ducts 211. The four parallel outlet channels 211 have the advantage that they have an improved flow with a changed Reynolds number compared to an outlet with only one outlet channel. In this case, the four parallel outlet channels 311 overall form an improved flow cross section. The flow resistance is reduced by the improved flow cross section. In addition to a better flow behavior, this has the consequence that the ball 4 releases from the blocking position more quickly and the valve mechanism reacts more sensitively to a changed flow.In embodiments which are not shown, it can nevertheless be provided to provide only one outlet channel or another number of outlet channels, for example two, three, five or more outlet channels.The design and sealing of the valve chamber 5 will be discussed in more detail below. The second part 2 has, in the connecting region 290, a projection 20 with an external thread 29, via which the second part 2 is screwed into the first part 3. The end of the projection 20 is formed by a pointed sealing edge 27. A second blind bore 28 is let into the projection 20 on the end face, so that an intermediate space is formed when the first part 3 is screwed into the second part 2. This space forms the valve chamber 5.Accordingly, the inner wall of the valve chamber 5 is formed by the second blind bore 28, the pointed sealing edge 27 and the base surface 36.The pointed sealing edge 27 has an inner leg 25 and an outer leg 26 in cross section and is pressed with the tip against the base surface 36 of the first part 3. The pointed sealing edge 27 and the base 36 form a pointed seal. The tip seal is based on the principle that instead of a flat seal with a relatively large sealing surface, the sealing surface is kept as low as possible. For this purpose, the sealing surface is formed only by the contact of the tip of the pointed sealing edge 27 on the flat base surface 36. According to the physical principle according to which the following applies: pressure= force / surface, the surface to be sealed is thus minimized, so that the force required for the sealing effect is also reduced. As a result, it is sufficient that the first part 3 and the second part 2 are screwed manually for sufficient tightness.The sharp sealing edge 27 comprises the inner leg 25 and the outer leg 26. The outer leg 26 extends in the axial direction so that it is perpendicular to the base surface 36. The outer leg 26 does not lie against a side wall of the blind hole 30, but is spaced apart from it by a gap 51.When the sealing edge 27 is pressed against the base surface 36, the material at the tip of the sealing edge 27 is minimally deformed. The formation of the legs 25, 26 and the gap 51 ensures that the material of the tip of the sealing edge 27 deforms outwards into the gap 51 in a controlled manner. As a result of the controlled deformation, the valve chamber 5 is reliably sealed even at high pressures. In this case, there is no structural deformation which would result in a changed geometry of the valve chamber 5. Due to the pointed seal, polymeric components as sealing elements can be dispensed with.The valve chamber 5 is formed so that the valve ball 4 can freely move therein. The valve ball 5 has a clearance in all three spatial directions and is not guided through a wall of the valve chamber 5. The ball has a diameter of 1.75 mm, for example, and has at least a clearance in the radial direction of 0.2 mm with respect to the wall of the valve chamber. In this case, the valve chamber 5 is formed wider in a lower region of the seal than in an upper region of the second blind bore 28 by the tapered inner leg 25 of the sealing edge 27, with the result that the lateral clearance is greater here.In a similar manner to the sealing of the valve chamber 5, the two valve connections, namely the inlet 31 and the outlet 21, also have a pointed outer sealing edge 22, 32. The outer sealing edge 22, 32 serves to form an acute seal with a flat surface of a connected component, not shown. The outer sealing edge 22, 32 has two legs 23, 24 and 33, 34, respectively, which are at an angle of, for example, 45° to each other. The outer leg 24, 34 extends in the axial direction and the inner leg leads obliquely from the inlet duct 311 or the outlet ducts 211 to the tip of the outer sealing edge 22, 32.In order that the valve ball 4 effectively prevents the undesired flow in the blocking position, the transition between the valve chamber 5 and the inlet duct 311 is formed in a special manner. For this purpose, a curved surface 35 is formed between the base surface 36 and the inlet channel 311. The curved surface 35 corresponds in its shape to the shape of the valve ball 4, so that an optimum seal is provided in the blocked position.In an exemplary embodiment, the curved surface 35 is not formed in the first part 3 from the outset, but is formed by pressing in the ball 4 in the direction of the inlet 31. The first part has an edge between the base 36 and the inlet channel 311 in the original state. When the valve 1 is assembled, i.e. when the first part 3 is screwed to the second part 2 and the ball 4 is arranged in the valve chamber 5, the ball 4 is pressed in the direction of the inlet 31. For pressing in the ball 4, a high pressure is built up which is directed opposite to the direction of flow and presses the ball 4 into the blocking position. In this case, material at the edge of the first part 3 is deformed in a controlled manner by the ball 4, with the result that instead of the edge an outwardly curved surface 35 corresponding to the shape of the ball is formed.The ball has a harder material compared to the first part 3 and the second part 2. Thus, the two parts 2, 3 are manufactured, for example, from a titanium stainless steel alloy or another material and the valve ball from rubin.FIGS. 2-5 show external views of the valve 1, respectively. the first part 3 and the second part 2 can be seen. The first part 3 comprises the outer sealing edge 32 at the inlet 31, and the second part 2 is screwed into the first part 3 via the thread 29 and has the outer sealing edge at the outlet 21. In this case, the four outlet ducts 211 arranged in parallel can be seen in FIGS. 3 and 4, whereas it can be seen in FIG. 5 that the inlet 31 comprises only one inlet duct 311.Figure 6 illustrates a typical use of the valve 1 with a first part 3, a second part 2 and a valve ball 4 in a pump head 100 for liquid chromatography.The two valves 1 shown define the flow direction in the pump head 100. The valves 1 are connected to one another by a valve shaft 102. A valve piston 101 is arranged in the valve shaft 102, which moves back and forth between the valves 1 and builds up a pressure in the fluid.The pump head 100 has two threaded bores 103 each with a stop 1031, against which the valves 1 are inserted. For fixing, valve connectors 105, 108 are screwed into the threaded bore 103. The valve stubs 105, 108 press the valve 1 against the stop 1031. A cutting ring 107, 109 (Farrow) is screwed into each of the valve stubs 105, 108, which connects the valve stub 105, 108 to a line in each case. Since significantly higher pressures are present at the outlet of the pump head 100 than at the inlet, there are greater requirements here on the strength of the components. Accordingly, the conduit that leads the fluid to the pump head 100 is a plastic hose 111, whereas the conduit that leads pressurized fluid out of the pump head 100 is a metal tube 107.It is noted that any of the described features may be used separately or in combination with any other features, unless they are mutually exclusive. The disclosure extends to and encompasses all combinations and sub-combinations of one or more features described herein. If ranges are defined, these include all values within these ranges and all sub-ranges that fall within a range.

Claims

Valve (1) having a flow direction, which has: - a first part (3) and a second part (2), - a valve ball (4), - wherein the two parts (2, 3) each have a valve connection (210, 310), a connecting region (290, 390) and a fluidic connection (211, 311) which is respectively arranged between the valve connection (210, 310) and the connecting region (290, 390), - wherein the valve connection (210, 310) is respectively designed such that the valve (1) can be connected to further components, - wherein the first part (3) and the second part (2) can be respectively connected to one another in the connecting region and both parts (2, 3) are designed together to form a valve chamber (5) which is formed between the two fluidic connections (211, 311), - wherein the valve connection (210), which is arranged downstream of the valve chamber (5) in the flow direction, forms a valve outlet (21) and the valve connection (310) which is arranged upstream of the valve chamber (5) in the flow direction forms a valve inlet (31), - wherein the valve ball (4) is arranged in the valve chamber (5) and blocks the flow through the valve chamber (5) in the event of a flow counter to the flow direction, characterized in that - the valve chamber (5) and the valve ball (4) are designed such that the valve ball (4) is freely movable in all three spatial planes in the valve chamber (5) and is not guided through a wall delimiting the valve chamber (5).Valve according to one of the preceding claims, characterized in that the first part (3) and the second part (2) can be sealed against one another via a tip seal, in which one of the two parts (2, 3) comprises a flat base surface (36) and the other part (2, 3) comprises a pointed sealing edge (27), wherein the tip seal is designed such that the pointed sealing edge (27) is pressed against the flat base surface (36).Valve according to Claim 2, characterized in that the tip seal has exclusively metallic elements.Valve according to Claim 2 or 3, characterized in that the tapered sealing edge (27) comprises, in cross section, two tapered limbs (25, 26) which have an angle in the range from 20° to 45°, in particular an angle of 29° to 31°.Valve according to Claim 4, characterized in that one of the limbs is an outer limb (26) of the sealing edge (27) which is remote from the fluid and runs parallel to the throughflow direction of the fluid.Valve according to one of the preceding claims, characterized in that at least one of the two valve connections comprises a further outer sealing edge (22, 32) for sealing with respect to a connected component, wherein the outer sealing edge (22, 32) comprises two tapered limbs (23, 24, 33, 34) in cross section.Valve according to Claim 6, characterized in that the angle between the limbs (23, 24, 33, 34) of the outer sealing edge (22, 32) is in a range from 40° to 50°, in particular in a range from 44° to 46°.Valve according to one of the preceding claims, characterized in that the fluidic connection between the valve chamber (5) and the valve outlet (21) has a plurality of outlet ducts (211).Valve according to Claim 8, characterized in that the fluidic connection (211) between the valve chamber (5) and the valve outlet (21) has four parallel outlet ducts (211).Valve according to one of the preceding claims, characterized in that the material of the valve ball (4) is harder in the sense of a greater penetration hardness compared to the material of the first part (3) and of the second part (3).Valve according to one of the preceding claims, characterized in that a sealing surface (35) is formed at the transition between the fluidic connection (311) coming from the inlet (31) and the valve chamber (5).Valve according to Claim 11, characterized in that the sealing surface (35) is of arched configuration corresponding to the valve ball (4).Valve according to Claim 12, characterized in that the curved sealing surface (35) is formed by deformation of material by pressing in the valve ball (4) in the direction of the inlet (31).Valve according to one of the preceding claims, characterized in that the first part (3) and the second part (2) consist of metal, in particular of a stainless steel alloy or a titanium alloy.Valve according to claim 14, characterised in that the first part (3) and the second part (2) consist of a stainless steel titanium alloy.Valve according to one of the preceding claims, characterized in that the valve (1) does not contain elements which consist of polymers.Valve according to one of the preceding claims, characterized in that the first part (3) and the second part (2) are each formed in one piece.Valve according to one of the preceding claims, characterized in that the valve comprises only the first part (3), the second part (2) and the valve ball (4).Valve according to one of the preceding claims, characterized in that the connecting region (290) of the first part (3) and the connecting region (390) of the second part (2) are screwed to one another via a thread (29, 39).Valve according to one of the preceding claims, characterized in that the valve ball (4) has a diameter in the range from 1.5 mm to 2.0 mm, in particular in the range from 1.745 mm to 1.755 mm.Valve according to one of the preceding claims, characterized in that the valve ball (4) has a movement clearance of at least 0.1 mm in a direction which runs transversely with respect to the throughflow direction.A pump for liquid chromatography comprising a pump head having a valve according to any preceding claim.

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