Conveying and dosing pump for conveying a freezable liquid

Abstract

The invention relates to a conveying and dosing pump (1) for conveying a freezable liquid, comprising a pump chamber (2) having a chamber housing (3) with a first chamber housing element (4) and a second chamber housing element (5), wherein the first chamber housing element (4) and the second chamber housing element (5) are braced against one another by at least one expandable tensioning element (6), wherein the at least one expandable tensioning element (6) is designed to allow a relative movement between the first chamber housing element (4) and the second chamber housing element (5) when ice pressure occurs in the pump chamber (2).

Description

[0001] Feed and dosing pump for conveying a freezable liquid

[0002] The invention relates to a feed and metering pump for conveying a freezable liquid. A freezable liquid is, for example, water, which freezes at 0° Celsius and undergoes volume expansion.

[0003] For pumps for freezable liquids, it is generally very advantageous if such pumps are not damaged by the liquid freezing inside the pump. The volume expansion during freezing or when ice forms inside the pump must then be accommodated. It is known to provide elastic elements within a pump that can release additional volume when ice occurs. However, such elastic elements require additional space within the pump. Furthermore, the elastic properties of such elements can also have a negative impact on pumping performance because, during pumping processes, part of the applied power may be deformed by such elastic elements and not transferred to the liquid.

[0004] Based on this, the object of the present invention is to at least partially solve the problems described with reference to the prior art. In particular, it is intended to present a particularly advantageous feed and metering pump for conveying freezable media.

[0005] This object is achieved by the invention according to the features of the independent patent claims. Further advantageous embodiments are specified in the dependent claims as well as in the description and, in particular, in the description of the figures. It should be noted that the person skilled in the art can combine the individual features in a technologically expedient manner and thus arrive at further embodiments of the invention.What is to be described here is a feed and metering pump for feed a freezable liquid, comprising a pump chamber with a chamber housing having a first chamber housing element and a second chamber housing element, wherein the first chamber housing element and the second chamber housing element are clamped against one another by at least one expandable clamping element, wherein the at least one expandable clamping element is designed to enable a relative movement between the first chamber housing element and the second chamber housing element when ice pressure occurs in the pump chamber.

[0006] The described feed and metering pump is therefore particularly preferably designed in such a way that a freezable liquid can remain in the pump and freeze there without the pump being destroyed and / or damaged.

[0007] Instead of providing elastic elements within the pump to absorb an increase in volume when ice forms, it is proposed here to construct the chamber housing of the pump as a whole in several parts and to use expandable clamping elements to clamp individual chamber housing elements against each other in such a way that when ice occurs in the pump, relative movements of the chamber housing elements to each other are possible.

[0008] The chamber housing is a structure that defines the outside of the pump chamber. The chamber housing separates the pump chamber from its surroundings. By “surroundings” or “outside” is meant a space around the chamber housing. A chamber housing in this sense is in particular not a movable wall section that is located inside the pump chamber or inside the chamber housing. A chamber housing element is a component that forms at least a substantial part of the chamber housing. The following describes, for example, chamber housing elements that each form approximately half the chamber housing, with a first chamber housing element and a second chamber housing element together forming the entire chamber housing. Chamber housing elements each define the shape of the pump chamber at least in part. The term “chamber housing element” does not include, for example:Plugs or similar elements that are inserted into openings and / or recesses of the chamber housing. Preferably, at least one of the two chamber housing elements has a convex shape that forms a portion of a pump chamber inner surface. Preferably, each of the individual chamber housing elements individually forms at least 30 percent of a pump chamber inner surface oriented toward the pump chamber.

[0009] It is particularly preferred if the at least one expandable clamping element comprises an expansion screw and / or an elastically deformable support sleeve.

[0010] An expansion screw preferably has an expandable shaft that is thinner than a threaded section with which the expansion screw is screwed into a thread. The expandable shaft can deform as a result of occurring forces and thus offers a defined degree of flexibility. A deformable support sleeve is preferably made of an elastic material, which is particularly preferably more elastic (has a lower modulus of elasticity) than the material of a screw. The elastic support sleeve is preferably compressed and prestressed by a screw connection. As a result of occurring ice pressure, forces in the expandable tensioning element (in the expansion screw or in elastically deformable support sleeves) preferably increase further.

[0011] It is particularly preferred if the first chamber housing element and the second chamber housing element abut one another at an interface, wherein a deformable sealing element is arranged at the interface, which deforms upon a relative movement of the first chamber housing element and the second chamber housing element to one another, and ensures a sealing of the pump chamber at the interface.

[0012] The deformable sealing element is, for example, a ring seal that lies in a groove at the interface in the first chamber housing element and / or in the second chamber housing element. The deformable sealing element is clamped between the chamber housing elements by the clamping force exerted on the chamber housing elements by the clamping elements. Preferably, the deformable sealing element and the clamping elements are designed such that the occurrence of ice or ice pressure in the pump chamber does not completely relieve the deformable sealing element, but rather the deformable sealing element expands and further seals the first chamber housing element and the second chamber housing element against one another. In the feed and metering pump described here, a functional separation is therefore preferably implemented. The deformable sealing element ensures the tightness of the pump chamber.The clamping elements enable the chamber housing elements to move relative to each other to compensate for ice pressure.

[0013] It is particularly preferred if the first chamber housing element and the second chamber housing element abut one another at an interface, wherein the interface forms a flat surface.

[0014] It is also preferred if a pump chamber inlet and a pump chamber outlet of the pump chamber are formed in the first chamber housing element and the second chamber housing element is closed.

[0015] In this design variant, the second chamber housing element is a kind of (passive) cover of the chamber housing, while the first chamber housing element forms the liquid-carrying line connections of the pump chamber.

[0016] Other design variants are also included, in which the pump chamber inlet is designed, for example, in a first chamber housing element and the pump chamber outlet is designed in the (other) second chamber housing element.

[0017] It is also advantageous if at least one movable conveying element (for conveying the liquid) is arranged in the pump chamber, wherein the pump chamber and the conveying element are designed in such a way that the pump operates in the manner of a positive displacement pump and has at least one movable sealing point which is opened when ice forms in the pump.

[0018] For the pump to function, it is not necessary for the movable seal to open due to ice formation. However, it has been shown that opening of the movable seal can be permitted by a relative movement of the chamber housing elements. Opening the movable seal causes the pump to lose its internal seal. Fluid could then theoretically flow undesirably from the pump chamber inlet to the pump chamber outlet and vice versa. However, this lack of internal seal can be deliberately permitted if ice forms in the pump.

[0019] However, the pump or its components (in particular the deformable sealing element and the expandable clamping elements) are preferably designed so that the pump maintains external tightness when ice forms. In particular, when ice forms in the pump chamber, no leakage occurs that could allow fluid to escape from the pump. Most preferably, no leakage occurs at an interface between the chamber housing elements.

[0020] The feed pump is further advantageous if a movable feed element together with the pump chamber forms a displaceable sealing point which is moved over a sealing surface formed by the chamber housing when the feed and metering pump carries out a feed, wherein the sealing surface is formed at least partially by the first chamber housing element and at least partially by the second chamber housing element.

[0021] In this embodiment, a movable sealing point of the movable conveying element also passes over an interface between the first chamber housing element and the second chamber housing element during a conveying movement. A sealing surface seam preferably exists at the interface, forming the boundary between the chamber housing elements. The sealing surface seam is often critical because there is a (small) irregularity in the sealing surface that can impede conveying movement of the movable sealing point or the movable conveying element. However, it has been found that the sealing surface seam in the sealing surface is acceptable. The sealing surface seam preferably opens slightly when relative movement occurs between the chamber housing elements as a result of ice formation.However, this opening of the sealing surface seam only occurs in operating situations in which the pump is not delivering and no movement of the movable sealing point across the sealing surface seam is to be expected.

[0022] It is also preferred if a movable conveying element of the pump carries out at least one rotational movement as a conveying movement, wherein a rotational axis of the movable conveying element is aligned parallel to an interface between the first chamber housing element and the second chamber housing element.

[0023] In some designs, the pump can also have two movable pumping elements, both of which rotate (possibly in opposite directions) to pump the fluid. In other designs, it is also possible for the rotation axis to be arranged perpendicular to an interface.

[0024] It is especially preferred if the liquid is water. Water freezes at 0° Celsius and experiences significant volume expansion upon freezing. Such temperatures can occur frequently, especially in winter.

[0025] Also described here is a system for pumping an operating fluid for the operation of a motor vehicle, comprising a described feed and metering pump. Such a system can be used in particular in a motor vehicle, for example, to pump water as an operating fluid into an exhaust gas purification system and / or into an internal combustion engine.

[0026] The invention and the technical context of the invention are explained in more detail below with reference to the figures. The figures show preferred embodiments to which the invention is not limited. It should be noted in particular that the figures, and in particular the proportions depicted in the figures, are only schematic. They show:

[0027] Fig. 1: a first embodiment of a described feed and metering pump;

[0028] Fig. 2: a second embodiment of a described feed and metering pump; and

[0029] Fig. 3: a third embodiment of a described feed and dosing pump.

[0030] Figs. 1, 2 and 3 each show a feed and metering pump 1 with a pump chamber 2 formed by a chamber housing 3. The chamber housing 3 is designed in two parts, with a first chamber housing element 4 and a second chamber housing element 5. The two chamber housing elements 4, 5 are clamped against one another with expandable clamping elements 6, which generate a preload that clamps the two chamber housing elements 4, 5 against one another. The expandable clamping elements 6 are provided here, for example, on (circumferential) flanges 9 of the chamber housing elements 4, 5.

[0031] The expandable clamping elements 6 are each designed here with expansion screws 7 and deformable support sleeves 8. Expansion screws 7 and deformable support sleeves 8 or the expandable clamping elements 6 formed thereby are suitable for generating a prestress which clamps the two chamber housing elements 4, 5 against each other and which, when ice occurs in the pump chamber 2, also allows a reversible relative movement of the chamber housing elements 4, 5 relative to each other.

[0032] Between the chamber housing elements 4, 5 there is an interface 10, at which the chamber housing elements 4, 5 abut one another and at which a compressive force of the chamber housing elements 4, 5, generated by the expandable tensioning elements 6, acts on one another. At the interface 10, a deformable sealing element 11 also exists between the chamber housing elements 4, 5. Preferably, the deformable sealing element 11 is designed such that even in the event of a relative movement of the chamber housing elements 4, 5 to one another as a result of ice pressure, the deformable sealing element 11 maintains the tightness of the pump chamber 2.

[0033] The pump chamber 2 has a pump chamber inlet 12 and a pump chamber outlet 13. In the embodiments according to Figs. 1 and 3, the pump chamber inlet 12 and the pump chamber inlet 13 are each provided in a chamber housing element 4, namely the first pump chamber housing element 4. In the embodiment according to Fig. 2, a pump chamber inlet 12 is provided in the first chamber housing element 4 and a pump chamber outlet 13 is provided in the other, second chamber housing element 5.

[0034] The pump 1 has at least one movable conveying element 15 in each case. In the embodiment according to Fig. 2, two movable conveying elements 15 are even provided. The movable conveying elements 15 are preferably each movable about a rotation axis 18 in order to carry out a conveying movement. In the embodiments according to Figs. 1 and 2, these rotation axes 18 are aligned parallel to the interface 10 or, if appropriate, they may even lie in the interface 10. In the embodiment according to Fig. 3, the rotation axis 18 is arranged perpendicular to the interface 10. The movable conveying elements 15 preferably each move a displaceable sealing point 14, with which at least one defined conveying volume is displaced within the pump chamber 2. Particularly preferably, the displaceable sealing point 14 is displaced via a sealing surface 16 within the pump chamber 2.

[0035] In the embodiments according to Figs. 1 and 2, this sealing surface 16 is interrupted by a sealing surface seam 17 formed at the interface 10.

[0036] List of reference symbols

[0037] 1 feed and dosing pump

[0038] 2 pump chamber

[0039] 3 chamber housing

[0040] 4 first chamber housing element

[0041] 5 second chamber housing element

[0042] 6 stretchable tensioning element

[0043] 7 Expansion screw

[0044] 8 deformable support sleeves

[0045] 9 Flange

[0046] 10 Interface

[0047] 11 deformable sealing element

[0048] 12 Pump chamber inlet

[0049] 13 Pump chamber outlet

[0050] 14 movable sealing point

[0051] 15 Conveyor element

[0052] 16 Sealing surface

[0053] 17 Sealing surface seam

[0054] 18 Rotation axis

Claims

Claims 1. A feed and metering pump (1) for feeding a freezable liquid, comprising a pump chamber (2) with a chamber housing (3) with a first chamber housing element (4) and a second chamber housing element (5), wherein the first chamber housing element (4) and the second chamber housing element (5) are clamped against one another with at least one expandable clamping element (6), wherein the at least one expandable clamping element (6) is designed to enable a relative movement between the first chamber housing element (4) and the second chamber housing element (5) when ice pressure occurs in the pump chamber (2).

2. Feed and metering pump (1) according to claim 1, wherein the at least one expandable clamping element (6) comprises an expansion screw (7) and / or an elastically deformable support sleeve (8).

3. Feed and metering pump (1) according to one of the preceding claims, wherein the first chamber housing element (4) and the second chamber housing element (5) abut one another at an interface (10), wherein a deformable sealing element (11) is arranged at the interface (10), which deforms upon a relative movement of the first chamber housing element (4) and the second chamber housing element (5) to one another, and ensures a seal of the pump chamber (2) at the interface (10).

4. Feed and metering pump (1) according to one of the preceding claims, wherein the first chamber housing element (4) and the second chamber housing element (5) abut one another at an interface (10), the interface (10) forming a flat surface.

5. Feed and metering pump (1) according to one of the preceding claims, wherein a pump chamber inlet (12) and a pump chamber outlet (13) of the pump chamber (2) in the first chamber housing element (4) are formed and the second chamber housing element (5) is closed.

6. Feed and metering pump (1) according to one of the preceding claims, wherein at least one movable conveying element (15) for conveying the liquid is arranged in the pump chamber (2), wherein the pump chamber (2) and the conveying element (15) are designed such that the pump (1) operates in the manner of a positive displacement pump and has at least one displaceable sealing point (14) which is opened when ice forms in the pump (1).

7. Feed and metering pump (1) according to one of the preceding claims, wherein a movable feed element (15) together with the pump chamber (2) forms a displaceable sealing point (14) which is moved over a sealing surface (16) formed by the chamber housing (3) when the feed and metering pump (1) carries out a feed, wherein the sealing surface (16) is formed at least partially by the first chamber housing element (4) and at least partially by the second chamber housing element (5).

8. Feed and metering pump (1) according to one of the preceding claims, wherein a movable feed element (15) of the pump (1) carries out at least one rotational movement as a feed movement, wherein a rotation axis (18) of the movable feed element is aligned parallel to an interface (10) between the first chamber housing element (4) and the second chamber housing element (5).

9. Feed and metering pump (1) according to one of the preceding claims, wherein the liquid is water.

10. System for conveying an operating fluid for the operation of a motor vehicle, comprising a conveying and metering pump (1) according to one of the preceding claims.

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