Pulsation damper

Abstract

This application relates to a pulsation damper for slowing the flow of liquid from a pulsating pump. The damper includes a housing (1, 2) defining a flow chamber (7) having an inlet (9) and an outlet (10), the inlet for receiving liquid from the pump. An elastic diaphragm (3) is held by the housing to form the wall of the flow chamber (7), such that one side of the diaphragm faces the flow chamber and the opposite side opens to the atmosphere. The diaphragm (3) can be moved by the pressure difference between the liquid flow and the atmosphere to smooth the liquid flow through the flow chamber (7).

Description

Technical Field

[0001] This invention relates to a pulsation damper. More specifically, it relates to a pulsation damper for slowing fluid flow from a pulsating pump. The invention also relates to an assembly of a pulsation damper and a pulsating pump. Background Technology

[0002] A pulse pump is a pump that produces a periodically varying output flow. In some applications, such as beverage dispensing, in vitro diagnostics, and water cooling recirculation, it is desirable to make the flow as smooth as possible, as this can improve pump efficiency and dosage accuracy, as well as reduce noise and vibration in the system.

[0003] Pulsation dampers are known in the art. Typically, these pulsation dampers include a biased pressure-sensitive element positioned in a fluid flow path. A high-pressure pulse causes the pressure-sensitive element to deflect elastically, thereby absorbing some energy from the fluid flow during the high-pressure pulse, which is then returned to the fluid flow when the biased element returns via a biasing force.

[0004] US 2009 / 0101222 discloses a piston element as a pressure-sensitive element, which is biased by a deformable bellows. This is a relatively complex arrangement, and it is designed for relatively high flow rates >100 lpm.

[0005] US2002 / 0139426, US2003 / 0000588, and US2017 / 0350354 disclose dampers having a housing separated by a diaphragm. A chamber on the side of the diaphragm opposite to the fluid flow is pressurized to provide a return force to counteract pressure pulses in the fluid flow. Summary of the Invention

[0006] The object of this invention is to provide a simplified damper that is best suited for use at lower flow rates.

[0007] A recent example of this type of damper is the KNF FP 70, manufactured by KNF. This is a two-stage damper with a first stage located upstream of the pump and a second stage located downstream. The second stage houses a damping element, which appears to be a large, sponge-like element that provides a biasing force to the diaphragm. The damper is attached to the top of the pump and significantly increases the overall footprint of the assembly.

[0008] According to the present invention, a pulsation damper as described in claim 1 is provided.

[0009] This invention provides a damper that receives a pulsating fluid flow from a pump and actuates the diaphragm via a pressure difference between the fluid flow on one side of the diaphragm and the atmospheric pressure on the opposite side. Since the opposite side of the diaphragm is open to the atmosphere, there is no need to create and maintain a pressurized chamber. Instead, the damper operates using its own elasticity to counteract the pressure difference caused by the fluid flow pulses. This simplifies the assembly and operation of the damper.

[0010] This is a very simple structure. In the KNF FP70 damper, the portion from the pump outlet leads to the damper, where the diaphragm moves via a large damping element. In this invention, the diaphragm can move via the pressure difference between the liquid flow and the atmosphere. This simplifies the design because no damping element is required. The damper is designed such that the diaphragm can move only via the pressure difference between the liquid flow and the atmosphere. However, it is possible to implement a concept where some movement of the diaphragm is caused by a smaller-scale damping element, even if this is not necessary for the operation of the diaphragm. Preferably, at least 70%, more preferably at least 80%, and most preferably at least 90% of the peak return force on the diaphragm is provided by the pressure difference.

[0011] Since the diaphragm provides most or all of the peak return force, it is advantageous that it has relatively low stiffness.

[0012] Specifically, the stiffness ΔP / ΔV is preferably less than 7 kPa / cm. 3 (Where ΔP is the pressure change on the liquid in the flow chamber, and ΔV is the volume change in the flow chamber caused by this pressure change), more preferably less than 6 kPa / cm². 3 And the optimal value is less than 5 kPa / cm. 3 .

[0013] This is determined in use by applying a known pressure change ΔP across the diaphragm and measuring the height change ΔX of the liquid column in a tube of known size to calculate the volume change ΔV of the flow chamber caused by the deflection of the flow chamber.

[0014] The housing is preferably formed of two parts fixed together, with a diaphragm held between the two parts to seal the flow chamber. The two parts can be bolted together, but are preferably joined using ultrasonic welding.

[0015] More than one flow chamber can be incorporated into the damper to provide smoother damping operation. However, this is not necessary, and preferably the housing defines a single flow chamber.

[0016] Pulsating dampers can operate without damping elements, meaning that when the damper is subjected to abnormally high fluid pressures, all of that pressure acts on the diaphragm itself. This can overstretch the diaphragm and cause it to rupture. This can be addressed by providing a thicker diaphragm. However, other operational considerations may preclude a relatively thinner diaphragm.

[0017] To protect and support the diaphragm, the housing preferably covers the opposite side of the diaphragm and has at least one opening that allows the opposite side to access the atmosphere.

[0018] Preferably, the maximum gap between the opposite side of the diaphragm in its unstressed state and the facing shell is less than 3 mm, and more preferably less than 2 mm. If subjected to abnormally high pressure, the diaphragm will be pushed against the facing shell. Because of this relatively close proximity, the diaphragm will quickly reach the point where pressure is transmitted to the shell, thereby limiting the pressure differential across the diaphragm and preventing excessive stretching.

[0019] To improve the flexibility of the diaphragm, it is preferably relatively thin. Specifically, the thickness of the diaphragm away from its periphery is less than 1 mm.

[0020] Preferably, a tubular element is present that connects opposite sides of the diaphragm to the atmosphere. In the event of a diaphragm leak, the tubular element provides a port to allow an operator to attach a hose to recover the leaked liquid or to transfer the leaked liquid to a drain.

[0021] The diaphragm can be prefabricated with a non-planar configuration. However, preferably, the diaphragm is flat in the assembled damper where there is no fluid flow.

[0022] The diaphragm can be installed in an unstressed state. However, preferably, in the assembled damper where there is no fluid flow, the diaphragm is under tension. This prestressing of the diaphragm helps it provide the required level of return force.

[0023] The diaphragm can have any suitable shape, but it is preferably circular.

[0024] The invention extends to a component comprising a pulsation damper and a pulsation pump according to a first aspect of the invention, wherein the outlet of the pulsation pump is connected to the inlet of the pulsation damper. Thus, the pulsation damper operates at the outlet of the pulsation pump to smooth its flow.

[0025] The pulsation damper can be connected to the pump via suitable piping. This allows the conventional pump to remain unchanged and allows the user to easily and conveniently position the damper downstream of the pump.

[0026] Alternatively, the damper can be mounted on the pump housing. In this case, the damper is preferably mounted on the side wall of the housing. This is particularly suitable for rotary diaphragm pumps.

[0027] These pumps are often used in relatively constrained locations. Therefore, preferably, at least 70% of the damper's area is contained within the horizontal projection of the pump housing (excluding inlet / outlet piping). This means that the damper has little or no lateral protrusion beyond the pump housing, which will allow pumps with attached dampers to be used in many locations of currently used, unmodified pumps without moving existing components, or at least with minimal required relocation.

[0028] The maximum thickness of the damper is preferably less than 30% of the maximum thickness of the pump housing. This also contributes to the compactness of the assembly, since the thickness of the pump housing with the attached damper is not significantly greater than the thickness of the pump housing itself.

[0029] The pump outlet can be connected to the pulsation damper inlet via an external conduit. This allows existing pumps to be used with relatively minor modifications. However, the outlet of the pulsation pump is preferably connected to the liquid inlet of the pulsation damper via a connecting conduit within the pump and damper housings. This effectively integrates the connection between the two into their respective housings, resulting in a more compact design. Attached Figure Description

[0030] An example of a pulsation damper and an assembly of a pulsation damper and a pump will now be described with reference to the accompanying drawings, in which:

[0031] Figure 1 This is a cross-sectional view through the first pulsating damper;

[0032] Figure 2 This is an exploded perspective view of the first pulsation damper;

[0033] Figure 3 This is a cross-sectional perspective view of the first pulsation damper;

[0034] Figure 4 This is a perspective view of the first pulsation damper;

[0035] Figure 5 It is the second pulsation damper, and Figure 1 Similar views;

[0036] Figure 6 This shows the second pulsation damper, and... Figure 3 Similar views;

[0037] Figure 7 This is a perspective view of the first component of the pulsation damper and pump;

[0038] Figure 8 yes Figure 7 An exploded perspective view;

[0039] Figure 9 From and Figure 8An exploded perspective view of the first component viewed from the opposite side;

[0040] Figure 10 This is a plan view of the first component, in which some parts of the pulsation damper have been removed;

[0041] Figure 11 yes Figure 7 A cross-sectional perspective view of the components shown;

[0042] Figure 12 It is the second example component, and Figure 7 Similar views;

[0043] Figure 13 It is the second example, and Figure 9 Similar exploded perspective view;

[0044] Figure 14 It is a second example component including the connecting tube, and Figure 8 Similar views; and

[0045] Figure 15 The schematic view illustrates how to determine diaphragm stiffness. Detailed Implementation

[0046] Figures 1 to 4 A first example of a pulsation damper is shown. This pulsation damper is designed to be installed on a pipe downstream of a pump that generates pulsating flow. It is specifically designed for rotary diaphragm pumps, but can be used with any pump that generates pulsating flow, as pulsating flow is a typical characteristic of positive displacement pumps.

[0047] Pulsation dampers have a simple structure and are suitable for low-capacity / high-frequency pumps that typically operate at frequencies of 20-70 Hz and produce flow rates of 0.5 lpm to 5.5 lpm. These pumps are commonly used in applications such as beverage dispensing, in vitro diagnostics, and water cooling recirculation.

[0048] The pulsation damper in this example comprises only three components: a lower housing 1, an upper housing 2, and a diaphragm 3. These components have a generally circular construction. The diaphragm 3 has an outer edge 4, which is held in a groove 5 between the lower housing 1 and the upper housing 2. The lower housing 1 and the upper housing 2 have complementary rib / groove constructions 6, allowing the two housing components to be properly positioned. They are then fixed together, for example, by ultrasonic welding, to form... Figure 1 , Figure 3 and Figure 4 The completed assembly is shown. In the completed construction, the diaphragm 3 is held and sealed by its edge 4 located in the groove 5. Any method can be used to secure the lower housing 1 and the upper housing 2 together, such as adhesive or bolted connections.

[0049] The diaphragm 3 divides the housing into a lower chamber 7 and an upper chamber 8. The lower chamber 7 has a disc-shaped structure, an inlet 9 for receiving liquid from the pump outlet, and an outlet 10 located on the opposite side of the lower chamber 7, which connects to downstream equipment. The upper chamber 8 is provided with multiple vent holes 11, allowing the upper chamber 8 to vent to the atmosphere. A vent pipe 12 is arranged around the vent holes 11 to allow connection of auxiliary pipes in case of leakage through / around the diaphragm 3. (Example from...) Figure 1 It is clear that there is a relatively small gap between the upper surface of the diaphragm 3 and the upper shell 2. This limits the upward movement of the diaphragm 3, thereby preventing the diaphragm from overstretching under abnormally high liquid pressure.

[0050] The damper receives pulsating fluid flow from the pump into the lower chamber 7 via inlet 9. High-pressure pulses in this fluid flow create a pressure difference between the pressure in the lower chamber 7 and the atmospheric pressure in the upper chamber 8, causing the diaphragm 3 to deflect upwards. As the peak pressure passes, the elastic combination of the diaphragm and the lower pressure difference caused by the lower pressure in the lower chamber 7 causes the diaphragm 3 to move downwards, thus adding energy to the fluid flow when the inflow is at a relatively low pressure. This has the effect of smoothing the pulsating flow from the pump, making the flow through outlet 10 more constant than the inflow.

[0051] As can be seen from the instruction manual, a very simple damper can be used to achieve smooth flow. This damper does not require external power and does not require additional components such as springs, bellows, or sponges to provide elastic bias force.

[0052] Figure 5 and Figure 6 A second example of a damper is shown. This damper is constructed and operates as previously described, but with a larger housing 1 and larger diameter inlet 9 and outlet 10. It will be connected to a pump with a higher flow rate. The dimensions of inlet 9 and outlet 10 can be matched to the pump's outlet capacity. In all cases, the upper housing 2 can be identical, thus reducing parts inventory. In all cases, the diaphragm 3 can also be identical. However, the thickness of the diaphragm material can be adjusted to optimize it for the desired flow rate.

[0053] although Figures 1 to 6 An example of a pulsation damper that will be connected to the pipe downstream of the pump is shown, but Figures 7 to 14 An example of the components is shown, in which a pulsation damper is mounted on the pump housing.

[0054] Now refer to Figures 7 to 11 Examples describing this type of component.

[0055] This example shows a pump housing 20, which is an improved version of the pump housing currently used on the applicant's rotary diaphragm pump. Such pumps are known, for example, from EP 0819853 or WO 2019 / 016518. It has a pump chamber 23 that incorporates a rotary diaphragm (not shown) driven by a motor (not shown), but it is mounted to... Figure 7 and Figure 8 The rear of the pump housing 20 is shown. The standard pump outlet is blocked as described below. A damper 24 is mounted on the front face of the pump housing 20, replacing the conventional end plate. This will be described in more detail below.

[0056] The pump housing includes an inlet pipe 21 that leads to the pump chamber 23, as in the pump described above. A cap 22 covers the outlet in a conventional pump, effectively blocking it. Instead, an internal outlet pipe 26 is provided to connect the pump chamber 23 to the damper 24.

[0057] Damper 24 is generally similar to the reference Figures 1 to 6 The dampers described are constructed identically. Specifically, they include a lower housing 31, an upper housing 32, and a diaphragm 33. The lower housing 31 and the upper housing 32 are ultrasonically welded together to clamp the diaphragm 33 and hold the diaphragm edge 34, as shown. Figure 11 As shown and as previously described, diaphragm 33 forms a lower chamber 37 and an upper chamber 38 in damper 24, which operate in the manner previously described. Specifically, upper chamber 38 has a vent 41 to maintain the upper chamber at atmospheric pressure. Lower chamber 37 has an inlet 39 communicating with an internal outlet conduit 26, such that the pump's outlet flow communicates with damper 24 at inlet 39. Diaphragm 33 is shown in reference to... Figure 1 and Figure 6 The described method of operation is to smooth the flow at outlet 40 in the lower chamber 39.

[0058] The lower housing 31 is attached to the pump housing 20 by bolts passing through the screw hole 42.

[0059] from Figures 7 to 11 It is clear that the shape of the damper 24 is made to match the side profile of the pump housing 20 as closely as possible. This is not an exact match, as the top of the damper 24 is wider than the corresponding portion of the housing 20 to allow space for the internal outlet pipe 26 to communicate with the inlet 39. The aim is to add the damper 24 to the pump housing 20 without unduly increasing the size of the pump. As can be seen from the accompanying drawings, the height and maximum width of the assembly remain constant, and the pump (with the attached damper 24) could potentially be used in situations where pumps without additional dampers are currently in use. Although the damper 24 is wider than the pump housing 20 at the top, this is also the area where the pump has the inlet 21 and cap 22, so again, the overall width is not unduly increased in this area.

[0060] As mentioned above, the current design is based on an existing pump housing. If a custom pump housing is used, the dimensions of the pump housing and the damper can be matched even more closely. Preferably, at least 70% of the damper's area, excluding pipes 21 and 40, is contained within the horizontal projection of the pump housing 20.

[0061] Furthermore, efforts have been made to minimize the thickness of the damper 24 to maximize the likelihood of replacing the existing pump (without a damper) with a pump that has an attached damper, with little or no modification to surrounding components. For this purpose, the ventilation duct 12 from the previous example has been removed, and the area of ​​the diaphragm 33 has been maximized within a given region to provide optimal damping within the available damper thickness. As a result, the damper thickness will increase the thickness of the pump housing 20 by no more than 30%.

[0062] The second example is in Figures 12 to 14 It is shown in the figure. It is similar to the first component in most respects, and these features will not be described here. Common features are indicated by the same reference numerals.

[0063] The only difference between the examples is the manner in which the liquid flows between the pump housing 20 and the damper 24. The internal outlet pipe 26 is no longer present, and the liquid exits the pump chamber 23 through the conventional outlet pipe 43. In addition to the previously described outlet 40, a second damper pipe 44 leading to the lower chamber 37 is also provided in the damper 24.

[0064] An external conduit 45 connects between the outlet conduit 43 and the second damper conduit 44 to deliver liquid from the pump chamber 23 to the damper 24. The damper operates as previously described, and fluid is discharged at the outlet 40. In practice, the damper can operate in the opposite direction, allowing the outlet conduit 43 to be connected to the conduit 40, which then becomes the damper inlet, and the conduit 44 to operate as the outlet. This arrangement can be used if space does not permit a connection between the outlet conduit 43 and the conduit 44.

Claims

1. A pulsation damper for slowing down the flow of liquid from a pulsating pump, the pulsation damper comprising: A housing defining a flow chamber, wherein the inlet of the flow chamber is for receiving liquid from a pulsating pump, and the outlet of the flow chamber is for discharging liquid from the flow chamber; An elastic diaphragm, held by the housing, forms the wall of the flow chamber such that one side of the diaphragm faces the flow chamber and the opposite side of the diaphragm opens to the atmosphere; The diaphragm is capable of moving due to the pressure difference between the liquid flow and the atmosphere, thereby smoothing the liquid flow through the flow chamber.

2. The pulsation damper according to claim 1, wherein, The diaphragm moves solely by the pressure difference between the liquid flow and the atmosphere.

3. The pulsation damper according to claim 1 or 2, wherein, The stiffness ΔP / ΔV of the diaphragm is less than 7 kPa / cm. 3 (Where, ΔP is the pressure change across the diaphragm, and ΔV is the volume change in the flow chamber caused by the pressure change), preferably less than 6 kPa / cm². 3 More preferably less than 5 kPa / cm 3 .

4. The pulsation damper according to any of the preceding claims, wherein, The housing is formed by two parts connected together, and a diaphragm is held between the two parts to seal the flow chamber.

5. The pulsation damper according to any of the preceding claims, wherein, The housing defines a single flow chamber.

6. The pulsation damper according to any of the preceding claims, wherein, The housing covers the opposite side of the diaphragm and has at least one opening that allows the opposite side to access the atmosphere.

7. The pulsation damper according to claim 6, wherein, The maximum gap between the unstressed side of the diaphragm and the facing shell is less than 3 mm, and preferably less than 2 mm.

8. The pulsation damper according to any of the preceding claims, wherein, The thickness of the diaphragm away from its periphery is less than 1 mm.

9. The pulsation damper according to any of the preceding claims, wherein, It has a tubular element that connects opposite sides of the diaphragm to the atmosphere.

10. The pulsation damper according to any of the preceding claims, wherein, In the absence of liquid flow, the diaphragm is flat in the assembled pulsation damper.

11. The pulsation damper according to any of the preceding claims, wherein, In the absence of liquid flow, the diaphragm is under tension in the assembled pulsation damper.

12. The pulsation damper according to any of the preceding claims, wherein, The diaphragm is circular.

13. A component comprising a pulsating pump and a pulsating damper according to any of the preceding claims, wherein, The outlet of the pulsating pump is connected to the inlet of the pulsating damper.

14. The component of claim 13, wherein, The pulsation damper is mounted on the housing of the pulsation pump.

15. The component according to claim 13 or 14, wherein, The pulsation damper is mounted on the side wall of the housing.

16. The component of claim 15, wherein, Apart from the inlet / outlet pipes, at least 70% of the area of ​​the pulsation damper is contained within the horizontal projection of the housing of the pulsation pump.

17. The component according to claim 15 or 16, wherein, The maximum thickness of the pulsation damper is less than 30% of the maximum thickness of the housing of the pulsation pump.

18. The component according to any one of claims 13 to 17, wherein, The outlet of the pulsating pump is connected to the liquid inlet of the pulsating damper via a connecting pipe in the housing of the pulsating pump and the housing of the pulsating damper.

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