EP1953387A2 - Positive displacement pump for transporting a fluid with automatic adaptation to the compressibility of the fluid - Google Patents
Positive displacement pump for transporting a fluid with automatic adaptation to the compressibility of the fluid Download PDFInfo
- Publication number
- EP1953387A2 EP1953387A2 EP08000832A EP08000832A EP1953387A2 EP 1953387 A2 EP1953387 A2 EP 1953387A2 EP 08000832 A EP08000832 A EP 08000832A EP 08000832 A EP08000832 A EP 08000832A EP 1953387 A2 EP1953387 A2 EP 1953387A2
- Authority
- EP
- European Patent Office
- Prior art keywords
- pumping chamber
- fluid
- positive displacement
- displacement pump
- rod
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
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Classifications
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
- F04B43/00—Machines, pumps, or pumping installations having flexible working members
- F04B43/02—Machines, pumps, or pumping installations having flexible working members having plate-like flexible members, e.g. diaphragms
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- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F04—POSITIVE - DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS FOR LIQUIDS OR ELASTIC FLUIDS
- F04B—POSITIVE-DISPLACEMENT MACHINES FOR LIQUIDS; PUMPS
- F04B45/00—Pumps or pumping installations having flexible working members and specially adapted for elastic fluids
- F04B45/04—Pumps or pumping installations having flexible working members and specially adapted for elastic fluids having plate-like flexible members, e.g. diaphragms
Definitions
- the invention relates to a positive displacement pump.
- Positive displacement pumps for transporting a fluid have been known for a long time.
- the dimensions and operating properties of such pumps are usually adapted to a particular type of fluid. They may in particular be adapted to the transport of a compressible fluid, such as a gas, or to the transport of an incompressible fluid, such as a liquid.
- a change in the composition, and thus the compressibility, of the fluid to be transported may, on the one hand, result in an unwanted reduction of the flow rate and, on the other hand, in an increased stress on the pump, in the worst case the pump may even be damaged.
- the goal of the invention is to create a positive displacement pump in which a suction or displacement element, respectively, comprising a diaphragm is connected to a drive device in an elastically sprung manner. Depending on the compressibility of the fluid to be transported, this spring element is more or less stressed during each pumping cycle. This leads to an increased suction capacity at a constant flow rate of the fluid while the stress, in particular on the moving parts of the pump, is reduced.
- a positive displacement pump 1 has a substantially cuboid-shaped housing 2 with a housing base 3 aligned perpendicularly to a longitudinal direction, a first and a second side wall 4 and 5, a housing back wall 6 and a housing cover 7. Additionally, the housing 2 may have a cover, not shown in the drawings, at the housing front side opposite the housing back wall 6.
- the housing cover 7 has a square cross-section in the direction perpendicular to the longitudinal axis and has a circular opening 8.
- the side walls 4 and 5 have the shape of an L, the width of the side walls 4 and 5 in the area of the housing cover 7 thus exceeding that in the area of the housing base 3.
- the housing is substantially mirror-symmetric to a central-longitudinal plane 51.
- the housing 2 consists of a solid material, such as plastics or metal.
- a suction or displacement element, respectively, comprising a flexible diaphragm 9 is located adjacent to the housing cover 7 opposite the housing base 3. In a plane perpendicular to the longitudinal direction, the diaphragm 9 has the same external dimensions as the housing cover 7 and completely covers the opening 8.
- Alternative embodiments of the displacement element, such as pistons, are also conceivable.
- a chamber cover plate 10 and a cap 11 are located adjacent thereto, both of which having, in a direction perpendicular to the longitudinal direction, the same external dimensions as the housing cover 7.
- the diaphragm 9 of a fluid-tight material, the chamber cover plate 10 and the cap 11 all have a cross-section in a direction perpendicular to the longitudinal direction which is identical to that of the housing cover 7.
- the chamber cover plate 10 On its side facing towards the diaphragm 9, the chamber cover plate 10 has a recess in the shape of a spherical segment which is substantially rotation-symmetric to the longitudinal axis and is thus plane-concave.
- the diaphragm 9, the chamber cover plate 10 and the cap 11 have one bore each 13 in each corner for receiving a cap screw 12.
- Each of the cap screws 12 engages with a corresponding threaded bore 14 in the housing 2.
- the housing 2, the diaphragm 9, the chamber cover plate 10 and the cap 11 are safely held in place.
- the diaphragm 9 is clamped in an immovable and/or gas- or fluid-tight manner along its edge between the housing cover 7 and the chamber cover plate 10.
- the diaphragm 9 In its central area covering the opening 8, the diaphragm 9 is displaceable along the longitudinal axis in a way as to pass through the opening 8 on the one hand and into the spherical-segment shaped recess of the chamber cover plate 10 on the other hand until it bears against the chamber cover plate 10.
- the chamber cover plate 10 on the one hand and the diaphragm 9 on the other hand define, or delimit, a pumping chamber 15 with a variable volume V.
- the chamber cover plate 10 has at least one inlet opening 16 disposed, or arranged, slightly off-centre and at least one outlet opening 17. Via the inlet opening 16, the pumping chamber 15 is connected to a suction channel 20 in the cap 11.
- a suction valve 19 is disposed between the suction channel 20 and the inlet opening 16.
- the suction valve 19 comprises a flexible non-return flap.
- the non-return flap is pivotally disposed in a suction passage 18 between the chamber cover plate 10 and the cap 11. A part of the cap 11 forms a stop for the non-return flap.
- the suction valve 19 is configured in a way as to allow fluid to enter the pumping chamber 15 in an inlet direction 21 through a suction channel 20, the suction passage 18 and the inlet opening 16 but prevents a fluid flow in the opposite direction, i.e. from the pumping chamber 15 through the inlet opening 16 and the suction passage 18 into the suction channel 20.
- the outlet opening 17, is connected to an outlet channel 24 in the cap 11 by means of an outlet valve 22 also comprising a flexible non-return flap in a discharge passage 23.
- the outlet valve 22 enables fluid to be discharged from the pumping chamber 15 through the outlet opening 17 into the outlet channel 24 but prevents a backflow of the fluid opposite to the discharge direction 25 into the pumping chamber 15.
- a part of the chamber cover plate 10 forms a stop for the non-return flap of the outlet valve 22.
- the suction channel 20 and the outlet channel 24 may for example be configured as bores or independent pipes in the cap 11.
- Alternative designs of the suction or outlet valve 19, 22, respectively, are conceivable.
- a motor 26 is attached to the outside of the housing back wall 6 in a non-rotational manner by means of fixing screws 27.
- the motor 26 has a shaft 28 which projects into the inside of the housing 2 through a recess, not shown in the figures, in the housing back wall 6.
- a drive device 29 is attached to the shaft 28.
- the drive device 29 may be driven by means of alternative drives such as a linear or piezoelectric drive.
- the drive device 29 comprises an eccentric disk 30, a rod 32 connected to the eccentric disk 30 in a virtually frictionless manner by means of a bearing 31, and a diaphragm connecting element 34 which is displaceable along the rod 32 and spring-mounted by means of a spring element in the shape of a leaf spring 33.
- the spring element is replaceable.
- the eccentric disk 30 has a circular cross-section with a symmetry axis and is eccentrically secured to the shaft 28, which is mounted rotatably about an axis of rotation 35, by means of a force-fit and/or a form-fit and/or bonding.
- the symmetry axis of the circular eccentric disk 30 is located at a distance d from the axis of rotation 35.
- the bearing 31 may be a slide bearing or, advantageously, a rolling-element bearing. The distance d delimits the maximum travel, or displacement, of the diaphragm 9 and, therefore, the maximum displacement volume of the positive displacement pump 1.
- the rod 32 has a longitudinal rod axis 50 and is substantially symmetric to the central longitudinal plane 51 when in the top or bottom dead-centre position, respectively, i.e. when the symmetry axis of the eccentric disk 30 and the longitudinal rod axis 50 coincide with the central longitudinal plane 51.
- the diaphragm connecting element 34 is spring-mounted in the rod 32 and is displaceable along the longitudinal rod axis 50.
- the diaphragm connecting element 34 is secured to the leaf spring 33 by means of a force-fit and/or a form-fit and/or bonding.
- the leaf spring 33 is force-fitted and/or form-fitted to the rod 32.
- the leaf spring 33 is mounted in a rod recess 36 in the rod 32 in an elastically deformable manner.
- the rod recess 36 substantially has the shape of a D.
- a through-opening 38 passes through the upper stop 37.
- the lower stop 39 substantially has the shape of a circular arc. Passing through the through opening 38, the diaphragm connecting element 34 is disposed between the leaf spring 33 in the rod recess 36 and the diaphragm 9. In this position, the diaphragm connecting element 34 is at least force-fitted to both the leaf spring 33 and the diaphragm 9.
- the diaphragm connecting element 34 may be integral with the leaf spring 33.
- the diaphragm connecting element 34 has a cylindrical projection 42.
- the diaphragm 9 On the side facing towards the diaphragm connecting element 34, the diaphragm 9 has a hollow cylindrical recess 40 into which the cylindrical projection 42 is inserted in a form-fit engagement.
- the spring element is a helical compression spring 33a.
- the helical compression spring 33a is replaceable.
- the rod recess 36a has a substantially cuboid shape.
- the helical compression spring 33a is disposed on the rod 32a on a cylindrical spring mandrel 41 disposed in the centre of the rod recess 36a.
- the length of the spring mandrel 41 at least equals the length of the helical compression spring 33a in a fully compressed state.
- the diaphragm connecting element 34a comprises a hollow cylinder which is substantially closed on one side and surrounds the helical compression spring 33a.
- the cylinder barrel may be interrupted, thus ensuring that the diaphragm connecting element 34a does not protrude beyond the rod 32a in the direction of the axis of rotation 35.
- the diaphragm connecting element 34a is form-fitted to the receiving element 40 of the diaphragm 9 by means of the cylindrical projection 42.
- a stop collar 43a is attached to the outside of the cylinder barrel.
- the diaphragm connecting element 34a is thus mounted in the rod recess 36a for displacement in the longitudinal direction, with the stop collar 43a bearing against the upper stops 37a in a first end position and against the lower stop 39a in a second end position.
- the lower stops 39a are plane and extend parallel to the upper stops 37a.
- the front wall closing one end of the hollow cylinder is advantageously flush with the spring mandrel 41. In that case, it is not absolutely necessary for the stop collar 43 to bear against the lower stops 39a in the second end position.
- the length and compressibility of the helical compression spring 33a are adapted to the dimensions of the spring mandrel 41, or in particular to the distance between the upper stops 37a and the lower stops 39a, in a way that said helical compression spring 33a is pre-stressed both in the first end position of the diaphragm connecting element 34a as well as in the second end position of the diaphragm connecting element 34a.
- the spring element comprises an elastomer spring 33b.
- the elastomer spring 33b is replaceable. It is advantageously made of an elastically deformable plastic material, such as EPDM or NBR.
- the elastomer spring 33b has a substantially cuboid shape, with a length 1 along the longitudinal rod axis 50, a depth t in the direction of the axis of rotation 35 and a width b perpendicular to the two other directions.
- the rod recess 36b has a substantially cuboid shape. It may be delimited by a support plate 44 on the side facing towards the housing back wall 6. Moreover, the recess 36b may be at least partially delimited by another support plate on the side facing away from the housing back wall 6. In the direction of the longitudinal rod axis 50, the recess has upper and lower stops 37b and 39b.
- the diaphragm connecting element 34b has an angled U-profile. Stop collars 43b are disposed on the outside of the two free ends of the U-profile.
- the cylindrical projection 42 is disposed on the side of the U-profile facing towards the diaphragm 9.
- the pumping cycle may substantially be subdivided into two phases, i.e. a suction phase on the one hand during which the suction valve 19 is open and fluid enters the pumping chamber 15 through the suction channel 20 and the inlet opening 16 while the outlet valve 22 is closed, thus preventing a backflow of fluid opposite to the discharge direction from the outlet channel 24 into the pumping chamber 15, and a discharge phase on the other hand during which the suction valve 19 is closed and the outlet valve 22 is open, thus preventing a backflow of fluid opposite to the inlet direction 21 from the pumping chamber 15 through the suction channel 20, and enabling fluid to flow through the outlet channel 24 and out of the pumping chamber 15 in the discharge direction 25.
- a suction phase on the one hand during which the suction valve 19 is open and fluid enters the pumping chamber 15 through the suction channel 20 and the inlet opening 16 while the outlet valve 22 is closed
- one of the two valves 19, 22 is open at a particular time substantially during the normal operation of the positive displacement pump 1, while the other of the two valves 19, 22 is closed, and vice versa.
- the pressure difference applied to the valve 19 or 22, respectively i.e. the difference between the fluid pressure pK(t) in the pumping chamber 15 and the pressure pI in the suction channel 20 or the pressure pO in the outlet channel 24, respectively, determines whether the valve 19 or 22, respectively, is open or closed.
- pO ⁇ pI with both pO as well as pI being substantially constant at least for the duration of a cycle.
- the fluid pressure pK(t) in the pumping chamber 15 varies cyclically due to the movement of the drive device 29, in particular the corresponding movement of the diaphragm 9, thereby causing a cyclic variation of the volume V(t) of the pumping chamber 15.
- the pressure pK(t) in the pumping chamber 15 may be increased by reducing the volume V(t) while the pressure pK(t) in the pumping chamber 15 may be reduced by increasing the volume V(t).
- the goal of the positive displacement pump 1 according to the invention is to connect the diaphragm 9 to the rod 32 in a spring-mounted manner by means of a spring element 33; 33a; 33b, thereby damping in particular the pressure increase or pressure reduction, respectively, in the pumping chamber 15, the amount of damping being a function of the stiffness of the spring element 33; 33a; 33b and said pressure increase or pressure reduction, respectively, depending on the compressibility of the fluid to be transported.
- the shaft 28 is driven by a motor 26 about the axis of rotation 35 in a direction of rotation 45.
- the following is a description of a complete pumping cycle starting from a top dead centre position of the drive device 29.
- a pumping cycle is described during which the spring element 33; 33a; 33b is rigid, therefore not changing its shape. This may be the case during the transport of a compressible fluid and/or at a low speed of rotation of the shaft 28 and/or if the spring element 33; 33a; 33b is very stiff.
- the diaphragm 9 is substantially pressed against the concave side of the chamber cover plate 10 ( Fig. 2 ; Fig.
- the pumping chamber 15 has a minimum volume.
- a rotation of the shaft 28 in the direction of rotation 45 causes the diaphragm 9 to be pulled away from the chamber cover plate 10 ( Fig. 3 ; Fig. 10 ; Fig. 17 ).
- the volume of the pumping chamber 15 increases.
- pK(t) is reduced.
- a relative low pressure is generated in the pumping chamber 15, with pK(t) ⁇ pI.
- This causes the outlet valve 22 to close the outlet opening 17 while the suction valve 19 opens, thus enabling fluid to flow into the pumping chamber 15 through the suction channel 20, the suction passage 18 and the inlet opening 16.
- the rotation of the eccentric disk 30 causes the volume of the pumping chamber 15 to increase until the drive device 29 has reached the bottom dead centre ( Fig. 4 ; Fig. 11 , Fig. 18 ).
- a further rotation of the eccentric disk 30 in the direction of rotation 45 causes the diaphragm 9 to be pressed in the direction towards the chamber cover plate 10, thereby reducing the volume of the pumping chamber 15. Consequently, the pressure pK(t) in the pumping chamber increases.
- a relative overpressure is generated in the pumping chamber 15, with pK(t) > pO.
- the overpressure in the pumping chamber 15 causes the suction valve 19 to close, thus preventing a backflow of the fluid from the pumping chamber 15 through the inlet opening 16 and into the suction channel 20. Moreover, the overpressure in the pressure chamber 15 causes the outlet valve 22 to open, thus enabling the fluid to flow out of the pumping chamber 15 through the outlet opening 17 and into the outlet channel 24. A further rotation of the eccentric disk 30 in the direction of rotation 45 reduces the volume of the pumping chamber 15 until the drive device 29 has reached the top dead centre (cf. Fig. 2 ; Fig. 9 ; Fig. 16 ) again.
- the volume of the pump chamber 15 increases, this in turn causing the pumping chamber pressure pK(t) to be reduced to a low pressure in the pumping chamber 15, pK(t) ⁇ pI.
- the low pressure if pK(t) > pI, causes the suction valve 19 to open, thus enabling fluid to flow from the suction channel 20 through the inlet opening 16 and into the pumping chamber 15.
- the volume of the pumping chamber 15 increases until the drive device 29 has reached the bottom dead centre ( Fig. 4 ; Fig. 11 ; Fig. 18 ).
- a further rotation of the eccentric disk 30 about the axis of rotation 35 then reduces the distance along the longitudinal rod axis 50 between the drive device 29 and the diaphragm 9.
- the force acting on the spring element 33; 33a; 33b increases, thus causing the diaphragm connecting element 34; 34a; 34b to be displaced in the rod recess 36; 36a; 36b until the force of the spring element 33; 33a; 33b acting on the diaphragm connecting element 34; 34a; 34b prevents any further displacement, at the most until the diaphragm connecting element 34; 34a; 34b comes to bear against the lower stops 39; 39a; 39b or the spring mandrel 41, respectively ( Fig. 7 ; Fig. 14 ; Fig. 21 ).
- the rod 32; 32a; 32b presses the diaphragm 9 in the direction towards the chamber cover plate 10 by means of the diaphragm connecting element 34; 34a; 34b, thus causing the volume of the pumping chamber 15 to be reduced.
- the outlet valve 22 opens ifpK(t) > pO, thus enabling the fluid to flow out of the pumping chamber 15 in the discharge direction 25, i.e. through the outlet opening 17 and into the outlet channel 24.
- the volume of the pumping chamber 15 reduces until the drive device 29 has reached its top dead centre ( Fig. 6 ; Fig. 13 ; Fig. 20 ).
- Both the extent of deformation of the spring element 33; 33a; 33b during a particular cycle and the particular phase of the cycle during which the diaphragm connecting element 34; 34a; 34b comes to bear against the upper stop 37; 37a; 37b and, as the case may be, against the lower stop 39; 39a; 39 are individually determined by, amongst other things, the compressibility of the fluid to be transported, the speed of rotation of the shaft 28 and the stiffness of the spring element 33; 33a; 33b.
- Force peaks on the drive device 29, the diaphragm 9, the pumping chamber 15 and the valves 19, 22 occurring in particular in the top or bottom dead centre position, respectively, are damped due to the diaphragm 9 being spring-mounted to the drive device 29.
- a systematic selection of a spring element 33; 33a; 33b having corresponding damping properties enables the positive displacement pump 1 to be specifically adapted to the expected operating conditions. Thereby, the suction capacity of the positive displacement pump 1 may be optimized, depending on the fluid to be transported, while reducing the stress on the positive displacement pump 1, in particular on the moving parts thereof.
- the displacement volume of the positive displacement pump 1 is automatically adapted to the compressibility of the fluid to be transported and to the drive speed of the drive device 29.
- the less the displacement of the diaphragm connecting element 34; 34a; 34b in the rod recess 36; 36a; 36b during a pumping cycle i.e. the higher the compressibility of the fluid to be transported while using the same spring element 33; 33a; 33b, or the stiffer the spring element 33; 33a; 33b while retaining the compressibility of the fluid to be transported, respectively, the larger the compression ratio of the fluid to be transported in the pumping chamber 15.
- a softer spring element 33; 33a; 33b causes the compression ratio, and thus me displacement volume of the positive displacement pump 1, to be reduced.
- the rod 32c comprises a rod drive area 46 which is concentric with the eccentric disk 30, two rod recess side walls 47 extending parallel to the longitudinal rod axis 50 and tangentially adjoining said rod drive area 46 in an integral manner as well as rod stop walls 48 which are integral with said rod-recess side walls 47.
- the upper rod stop walls 48 are deformable with respect to the rod-recess side walls 47.
- Each of the upper rod stop walls 48 has a free end 56 facing towards the through-opening 38c. When the rod 32c is unstressed, the upper rod stop walls 48 are substantially perpendicular to the rod-recess side walls 47.
- the rod-recess side walls 47 and the rod stop walls 48 form the spring element 32c.
- the side of the upper rod stop wall 48 facing towards the rod recess 36c forms the upper stop 37c for the diaphragm connecting element 34c.
- the lower stop 39c is formed by the side of the rod stop area 46 facing towards the rod recess 36c.
- the through-opening 38c disposed between the upper rod stop walls 48 is advantageously configured as a longitudinal recess extending in the direction parallel to the axis of rotation 35 along the entire depth of the rod 32c. This results in an improved deformability of the upper rod stop walls 48 with respect to the rod-recess side walls 47. Moreover, this provides for a simpler arrangement of the diaphragm connecting element 34c in the rod 32 during the assembly.
- the diaphragm connecting element 34c is slidable in particular over the rod 32c.
- the diaphragm connecting element 34c is symmetric, in particular rotation-symmetric, with respect to the longitudinal rod axis 50. It has a rod connecting portion 49 which is integral with the cylindrical projection 42.
- the rod connecting portion 49 comprises an upper transverse wall 52, a lower transverse wall 53 and a connecting piece 54 disposed therebetween.
- the upper transverse wall 52 and the lower transverse wall 53 define a bead-like groove 55.
- the diaphragm connecting element 34c is relatively stiff. In particular, the modulus of elasticity thereof exceeds that of the material the rod 32c is made of. This results in a particularly effective transmission of force from the rod 32c to the diaphragm 9.
- the diaphragm connecting element 34c may also be elastic, thus contributing to the resilience of the diaphragm 9.
- the diaphragm connecting element 34c is replaceable. It may be chosen in particular in accordance with the respective requirements.
- the side of the upper transverse wall 52 facing towards the groove 55 is positioned at an angle w 1 with respect to a horizontal plane which is perpendicular to the longitudinal rod axis 50.
- the angle w 1 is in the range of 1° to 10°.
- the side of the lower transverse wall 53 facing towards the groove 55 is positioned at an angle w 2 .
- the angle w 2 is in the range of 0.5° to 5°.
- the angle w 2 is in particular small enough to ensure a maximum deflection of the diaphragm 9 in the bottom dead centre position of the drive device 29c.
- the groove 55 thus widens outward. At its inner end, i.e. in the area of the connecting piece 54, the configuration of the groove 55 substantially corresponds to that of the free ends 56 of the upper rod stop walls 48. Each of the upper rod stop walls 48.is in engagement with the groove 55.
- the lower transverse wall 53 of the diaphragm connecting element 34c is thus disposed in the rod recess 36c. In the direction perpendicular to the longitudinal rod axis 50, the dimensions thereof are thus smaller than those of the rod recess 36c in this direction. Thus, a clearance is formed between the lower transverse wall 53 of the diaphragm connecting element 34c and the rod-recess side walls 47.
- the lower transverse wall 53 On its side facing towards the lower stop 39c, the lower transverse wall 53 has a central recess in the shape of a cylindrical portion the curvature of which just corresponds to that of the lower stop 39c in the area of the longitudinal rod axis 50.
- the rod 32c In the top dead centre position, shown in Fig. 22 , of the drive device 29c, the rod 32c is substantially mirror-symmetric to the central longitudinal plane 51. In this position, the dimension of the through-opening 38c in the direction perpendicular to the central longitudinal plane exceeds the dimension of the connecting piece 34 of the diaphragm connecting element 34c in the same direction.
- the diaphragm connecting element 34c is thus displaceable in the directions perpendicular to the longitudinal rod axis 50 and perpendicular to the axis of rotation 35.
- the functioning of the positive displacement pump 1 substantially corresponds to that of the previous embodiments to which reference is made.
- the function of the spring element 33c is performed by the elastic rod 32c, in particular by the upper rod stop walls 48.
- the rod 32c exerts a tensile force on the diaphragm connecting element 34c.
- the upper rod stop walls 48 increasingly come to bear against the lower transverse wall 53 of the diaphragm connecting element 34.
- the angle, measured inside the rod recess 36c, between the upper rod stop walls 48 and each of the rod-recess side walls 47 adjacent thereto increases more and more until it has reached the value of 90° + w 2 . In this position shown in Fig.
- the eccentric disk 30 performs a rotation in the direction of rotation 45 during the discharge phase, thus reducing the volume of the pumping chamber 15, the rod 32c exerts a thrust force on the diaphragm connecting element 34c.
- the upper rod stop wall 48 is increasingly pressed against the side of the upper transverse wall 52 of the diaphragm connecting element 34c facing towards the groove 55. The upper rod stop wall 48 is thus more and more pressed into the rod recess 36c.
- the angle between the upper rod stop wall 48 and each of the adjacent rod-recess side walls 47 is reduced to an angle of 90°-w 1 at which at least part of the surface of the upper rod stop wall 48 bears against the upper transverse wall 52.
- the respective sides of the upper transverse wall 52 and the lower transverse wall 53 of the diaphragm connecting element 34c facing towards the groove 55 are inclined by the angles w 1 or w 2 , respectively, thus ensuring that the diaphragm connecting element 34a gradually comes to bear against the upper rod stop wall 48.
- the elastic rod 32c is thus a spring element 33c providing a progressive damping effect.
- the damping behavior may be influenced by means of the exact configuration of the upper transverse wall 52 or the lower transverse wall, respectively.
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- Reciprocating Pumps (AREA)
Abstract
A positive displacement pump (1) for transporting a thud with automatic adaptation to the compressibility of that fluid has a pumping chamber (15) with a variable volume (V) which is on the one hand delimited by a rigid chamber cover plate (10) and on the other hand by an elastic diaphragm (9), a suction channel (29) which is in flow connection with the pumping chamber (15) for sucking the fluid to be transported into the pumping chamber (15), an outlet channel (24) which is in flow connection with the pumping chamber (15) for discharging the fluid to be transported from the pumping chamber (15), and a drive device (29) for cyclically increasing and reducing the current volume (V) of the pumping chamber (15), with the drive device (29) being connected to the diaphragm (9) by means of a diaphragm connecting element (34; 34a; 34b) which is spring-mounted in the drive device (29) by means of a spring element (33; 33a; 33b).
Description
- The invention relates to a positive displacement pump.
- Positive displacement pumps for transporting a fluid have been known for a long time. The dimensions and operating properties of such pumps are usually adapted to a particular type of fluid. They may in particular be adapted to the transport of a compressible fluid, such as a gas, or to the transport of an incompressible fluid, such as a liquid. A change in the composition, and thus the compressibility, of the fluid to be transported may, on the one hand, result in an unwanted reduction of the flow rate and, on the other hand, in an increased stress on the pump, in the worst case the pump may even be damaged.
- Thus it is the object of the invention to create a positive displacement pump whose mechanical properties, such as the suction capacity of the pump, automatically adapt to the compressibility of that fluid.
- This object is attained by the features of
claim 1. The goal of the invention is to create a positive displacement pump in which a suction or displacement element, respectively, comprising a diaphragm is connected to a drive device in an elastically sprung manner. Depending on the compressibility of the fluid to be transported, this spring element is more or less stressed during each pumping cycle. This leads to an increased suction capacity at a constant flow rate of the fluid while the stress, in particular on the moving parts of the pump, is reduced. - Further advantageous embodiments of the invention are stated in the subclaims.
- Further features and details of the invention will become apparent from the ensuing description of several embodiments, taken in conjunction with the drawings, in which
- Fig. 1
- shows an exploded view of a positive displacement pump according to a first embodiment;
- Fig. 2
- shows a central longitudinal section of the positive displacement pump according to
Fig. 1 with the spring element unstressed, such as during the transport of a compressible fluid at the beginning of a suction-discharge cycle; - Fig. 3
- shows a central longitudinal section of the positive displacement pump according to
Fig. 1 differing by a quarter cycle from the position shown inFig. 2 ; - Fig. 4
- shows a central longitudinal section of the positive displacement pump according to
Fig. 1 differing by a half cycle from the position shown inFig. 2 ; - Fig. 5
- shows a central longitudinal section of the positive displacement pump according to
Fig.1 differing by a three-quarter cycle from the position shown inFig. 2 ; - Fig. 6
- shows a central longitudinal section of the positive displacement pump according to
Fig. 1 corresponding to the position shown inFig. 2 but with the spring element stressed, such as during the transport of an incompressible fluid; - Fig. 7
- shows a central longitudinal section of the positive displacement pump according to
Fig. 1 corresponding to the position shown inFig. 5 but with the spring element stressed, such as during the transport of an incompressible fluid; - Fig. 8 to Fig. 14
- show a positive displacement pump according to a second embodiment corresponding to
Figs. 1 to 7 ; - Fig. 15 to Fig. 21
- show a positive displacement pump according to a third embodiment corresponding to
Figs. 1 to 7 ; and - Fig. 22 and Fig. 23
- show a positive displacement pump according to a fourth embodiment.
- The following is a description of a first embodiment, taken in conjunction with
Figs. 1 to 7 . - A
positive displacement pump 1 has a substantially cuboid-shaped housing 2 with ahousing base 3 aligned perpendicularly to a longitudinal direction, a first and asecond side wall housing back wall 6 and ahousing cover 7. Additionally, thehousing 2 may have a cover, not shown in the drawings, at the housing front side opposite thehousing back wall 6. Thehousing cover 7 has a square cross-section in the direction perpendicular to the longitudinal axis and has acircular opening 8. According to the embodiment shown in the drawings, theside walls side walls housing cover 7 thus exceeding that in the area of thehousing base 3. The housing is substantially mirror-symmetric to a central-longitudinal plane 51. Alternative geometric configurations of thehousing 2 are conceivable. Thehousing 2 consists of a solid material, such as plastics or metal. A suction or displacement element, respectively, comprising aflexible diaphragm 9 is located adjacent to thehousing cover 7 opposite thehousing base 3. In a plane perpendicular to the longitudinal direction, thediaphragm 9 has the same external dimensions as thehousing cover 7 and completely covers theopening 8. Alternative embodiments of the displacement element, such as pistons, are also conceivable. Achamber cover plate 10 and acap 11 are located adjacent thereto, both of which having, in a direction perpendicular to the longitudinal direction, the same external dimensions as thehousing cover 7. Thus, thediaphragm 9 of a fluid-tight material, thechamber cover plate 10 and thecap 11 all have a cross-section in a direction perpendicular to the longitudinal direction which is identical to that of thehousing cover 7. On its side facing towards thediaphragm 9, thechamber cover plate 10 has a recess in the shape of a spherical segment which is substantially rotation-symmetric to the longitudinal axis and is thus plane-concave. - The
diaphragm 9, thechamber cover plate 10 and thecap 11 have one bore each 13 in each corner for receiving acap screw 12. Each of thecap screws 12 engages with a corresponding threadedbore 14 in thehousing 2. By means of thecap screws 12, thehousing 2, thediaphragm 9, thechamber cover plate 10 and thecap 11 are safely held in place. In particular, thediaphragm 9 is clamped in an immovable and/or gas- or fluid-tight manner along its edge between thehousing cover 7 and thechamber cover plate 10. In its central area covering theopening 8, thediaphragm 9 is displaceable along the longitudinal axis in a way as to pass through theopening 8 on the one hand and into the spherical-segment shaped recess of thechamber cover plate 10 on the other hand until it bears against thechamber cover plate 10. - The
chamber cover plate 10 on the one hand and thediaphragm 9 on the other hand define, or delimit, apumping chamber 15 with a variable volume V. Thechamber cover plate 10 has at least one inlet opening 16 disposed, or arranged, slightly off-centre and at least one outlet opening 17. Via the inlet opening 16, thepumping chamber 15 is connected to asuction channel 20 in thecap 11. Asuction valve 19 is disposed between thesuction channel 20 and the inlet opening 16. Thesuction valve 19 comprises a flexible non-return flap. The non-return flap is pivotally disposed in asuction passage 18 between thechamber cover plate 10 and thecap 11. A part of thecap 11 forms a stop for the non-return flap. Thesuction valve 19 is configured in a way as to allow fluid to enter thepumping chamber 15 in aninlet direction 21 through asuction channel 20, thesuction passage 18 and the inlet opening 16 but prevents a fluid flow in the opposite direction, i.e. from thepumping chamber 15 through the inlet opening 16 and thesuction passage 18 into thesuction channel 20. The outlet opening 17, on the other hand, is connected to anoutlet channel 24 in thecap 11 by means of anoutlet valve 22 also comprising a flexible non-return flap in adischarge passage 23. Theoutlet valve 22 enables fluid to be discharged from thepumping chamber 15 through the outlet opening 17 into theoutlet channel 24 but prevents a backflow of the fluid opposite to thedischarge direction 25 into thepumping chamber 15. A part of thechamber cover plate 10 forms a stop for the non-return flap of theoutlet valve 22. Thesuction channel 20 and theoutlet channel 24 may for example be configured as bores or independent pipes in thecap 11. Alternative designs of the suction oroutlet valve - A
motor 26 is attached to the outside of thehousing back wall 6 in a non-rotational manner by means of fixingscrews 27. Themotor 26 has ashaft 28 which projects into the inside of thehousing 2 through a recess, not shown in the figures, in the housing backwall 6. Adrive device 29 is attached to theshaft 28. Thedrive device 29 may be driven by means of alternative drives such as a linear or piezoelectric drive. Thedrive device 29 comprises aneccentric disk 30, arod 32 connected to theeccentric disk 30 in a virtually frictionless manner by means of abearing 31, and adiaphragm connecting element 34 which is displaceable along therod 32 and spring-mounted by means of a spring element in the shape of aleaf spring 33. Advantageously, the spring element is replaceable. The spring elements illustrated in the description of the embodiments are only used as examples. Alternative embodiments of any type of the spring elements, such as gas springs, are conceivable. Theeccentric disk 30 has a circular cross-section with a symmetry axis and is eccentrically secured to theshaft 28, which is mounted rotatably about an axis ofrotation 35, by means of a force-fit and/or a form-fit and/or bonding. The symmetry axis of the circulareccentric disk 30 is located at a distance d from the axis ofrotation 35. Thebearing 31 may be a slide bearing or, advantageously, a rolling-element bearing. The distance d delimits the maximum travel, or displacement, of thediaphragm 9 and, therefore, the maximum displacement volume of thepositive displacement pump 1. - The
rod 32 has alongitudinal rod axis 50 and is substantially symmetric to the centrallongitudinal plane 51 when in the top or bottom dead-centre position, respectively, i.e. when the symmetry axis of theeccentric disk 30 and thelongitudinal rod axis 50 coincide with the centrallongitudinal plane 51. Thediaphragm connecting element 34 is spring-mounted in therod 32 and is displaceable along thelongitudinal rod axis 50. Moreover, thediaphragm connecting element 34 is secured to theleaf spring 33 by means of a force-fit and/or a form-fit and/or bonding. Additionally, theleaf spring 33 is force-fitted and/or form-fitted to therod 32. - The
leaf spring 33 is mounted in arod recess 36 in therod 32 in an elastically deformable manner. Therod recess 36 substantially has the shape of a D. On the side facing towards thediaphragm 9, it is delimited by a substantially flatupper stop 37. In the area of the central longitudinal plane of therod 32, a through-opening 38 passes through theupper stop 37. On the side of therod recess 36 opposite theupper stop 37, therod recess 36 is delimited by alower stop 39. Thelower stop 39 substantially has the shape of a circular arc. Passing through the throughopening 38, thediaphragm connecting element 34 is disposed between theleaf spring 33 in therod recess 36 and thediaphragm 9. In this position, thediaphragm connecting element 34 is at least force-fitted to both theleaf spring 33 and thediaphragm 9. Thediaphragm connecting element 34 may be integral with theleaf spring 33. - The
diaphragm connecting element 34 has acylindrical projection 42. On the side facing towards thediaphragm connecting element 34, thediaphragm 9 has a hollowcylindrical recess 40 into which thecylindrical projection 42 is inserted in a form-fit engagement. - The function of the pump is described further below.
- The following is a description of a second embodiment, taken in conjunction with
Figs. 8 to 14 . Identical parts are referred to with the same reference numerals as used for the first embodiment to the description of which reference is made. Parts that differ in design but have the same function are referred to with the same reference numerals with a subsequent a. The essential difference with respect to the first embodiment is that the spring element is ahelical compression spring 33a. Thehelical compression spring 33a is replaceable. Therod recess 36a has a substantially cuboid shape. Thehelical compression spring 33a is disposed on therod 32a on acylindrical spring mandrel 41 disposed in the centre of therod recess 36a. The length of thespring mandrel 41 at least equals the length of thehelical compression spring 33a in a fully compressed state. In this embodiment, thediaphragm connecting element 34a comprises a hollow cylinder which is substantially closed on one side and surrounds thehelical compression spring 33a. The cylinder barrel may be interrupted, thus ensuring that thediaphragm connecting element 34a does not protrude beyond therod 32a in the direction of the axis ofrotation 35. On the side facing towards thediaphragm 9, thediaphragm connecting element 34a is form-fitted to the receivingelement 40 of thediaphragm 9 by means of thecylindrical projection 42. At the open end of the cylindricaldiaphragm connecting element 34a, astop collar 43a is attached to the outside of the cylinder barrel. Thediaphragm connecting element 34a is thus mounted in therod recess 36a for displacement in the longitudinal direction, with thestop collar 43a bearing against theupper stops 37a in a first end position and against thelower stop 39a in a second end position. In this embodiment, thelower stops 39a are plane and extend parallel to theupper stops 37a. In the second end position, the front wall closing one end of the hollow cylinder is advantageously flush with thespring mandrel 41. In that case, it is not absolutely necessary for the stop collar 43 to bear against thelower stops 39a in the second end position. The length and compressibility of thehelical compression spring 33a are adapted to the dimensions of thespring mandrel 41, or in particular to the distance between theupper stops 37a and thelower stops 39a, in a way that saidhelical compression spring 33a is pre-stressed both in the first end position of thediaphragm connecting element 34a as well as in the second end position of thediaphragm connecting element 34a. - The function of this
positive displacement pump 1 is described further below. - The following is a description, taken in conjunction with
Figs. 15 to 21 , of another embodiment of the invention. Identical parts are referred to with the same reference numerals as used for the second embodiment to the description of which reference is made. Parts that differ in design but have the same function are referred to with the same reference numerals with a subsequent b. The essential difference with respect to the second embodiment is that the spring element comprises anelastomer spring 33b. Theelastomer spring 33b is replaceable. It is advantageously made of an elastically deformable plastic material, such as EPDM or NBR. Theelastomer spring 33b has a substantially cuboid shape, with alength 1 along thelongitudinal rod axis 50, a depth t in the direction of the axis ofrotation 35 and a width b perpendicular to the two other directions. Therod recess 36b has a substantially cuboid shape. It may be delimited by asupport plate 44 on the side facing towards the housing backwall 6. Moreover, therecess 36b may be at least partially delimited by another support plate on the side facing away from the housing backwall 6. In the direction of thelongitudinal rod axis 50, the recess has upper andlower stops diaphragm connecting element 34b has an angled U-profile. Stopcollars 43b are disposed on the outside of the two free ends of the U-profile. Thecylindrical projection 42 is disposed on the side of the U-profile facing towards thediaphragm 9. - The following is a description of the functioning of the
positive displacement pump 1 according to the previous embodiments. During the operation of thepositive displacement pump 1, the pumping cycle may substantially be subdivided into two phases, i.e. a suction phase on the one hand during which thesuction valve 19 is open and fluid enters the pumpingchamber 15 through thesuction channel 20 and the inlet opening 16 while theoutlet valve 22 is closed, thus preventing a backflow of fluid opposite to the discharge direction from theoutlet channel 24 into the pumpingchamber 15, and a discharge phase on the other hand during which thesuction valve 19 is closed and theoutlet valve 22 is open, thus preventing a backflow of fluid opposite to theinlet direction 21 from the pumpingchamber 15 through thesuction channel 20, and enabling fluid to flow through theoutlet channel 24 and out of the pumpingchamber 15 in thedischarge direction 25. - Therefore, one of the two
valves positive displacement pump 1, while the other of the twovalves valve pumping chamber 15 and the pressure pI in thesuction channel 20 or the pressure pO in theoutlet channel 24, respectively, determines whether thevalve pumping chamber 15, however, varies cyclically due to the movement of thedrive device 29, in particular the corresponding movement of thediaphragm 9, thereby causing a cyclic variation of the volume V(t) of the pumpingchamber 15. Generally, the pressure pK(t) in thepumping chamber 15 may be increased by reducing the volume V(t) while the pressure pK(t) in thepumping chamber 15 may be reduced by increasing the volume V(t). The exact details of the pressure increase or pressure reduction, respectively, depend amongst other things on the speed of rotation of theshaft 28 about the axis ofrotation 35, the geometric shape of theinlet opening 16 and the outlet opening 17 or theinlet channel 20 and theoutlet channel 24, respectively, the mechanical properties of thesuction valve 19 and theoutlet valve 22, the viscosity and compressibility of the fluid to be transported as well as the properties of thespring element 33; 33a; 33b. The goal of thepositive displacement pump 1 according to the invention is to connect thediaphragm 9 to therod 32 in a spring-mounted manner by means of aspring element 33; 33a; 33b, thereby damping in particular the pressure increase or pressure reduction, respectively, in thepumping chamber 15, the amount of damping being a function of the stiffness of thespring element 33; 33a; 33b and said pressure increase or pressure reduction, respectively, depending on the compressibility of the fluid to be transported. - During the normal operation of the
positive displacement pump 1, theshaft 28 is driven by amotor 26 about the axis ofrotation 35 in a direction of rotation 45.The following is a description of a complete pumping cycle starting from a top dead centre position of thedrive device 29. First of all, a pumping cycle is described during which thespring element 33; 33a; 33b is rigid, therefore not changing its shape. This may be the case during the transport of a compressible fluid and/or at a low speed of rotation of theshaft 28 and/or if thespring element 33; 33a; 33b is very stiff. In the top dead centre position of thedrive device 29, thediaphragm 9 is substantially pressed against the concave side of the chamber cover plate 10 (Fig. 2 ;Fig. 9 ;Fig. 16 ). In this position, the pumpingchamber 15 has a minimum volume. A rotation of theshaft 28 in the direction ofrotation 45 causes thediaphragm 9 to be pulled away from the chamber cover plate 10 (Fig. 3 ;Fig. 10 ;Fig. 17 ). Thereby, the volume of the pumpingchamber 15 increases. When the volume of the pumpingchamber 15 increases, pK(t) is reduced. Thus, a relative low pressure is generated in thepumping chamber 15, with pK(t) < pI. This causes theoutlet valve 22 to close theoutlet opening 17 while thesuction valve 19 opens, thus enabling fluid to flow into the pumpingchamber 15 through thesuction channel 20, thesuction passage 18 and theinlet opening 16. The rotation of theeccentric disk 30 causes the volume of the pumpingchamber 15 to increase until thedrive device 29 has reached the bottom dead centre (Fig. 4 ;Fig. 11 ,Fig. 18 ).A further rotation of theeccentric disk 30 in the direction of rotation 45 (Fig. 5 ,Fig. 12 ,Fig. 19 ) causes thediaphragm 9 to be pressed in the direction towards thechamber cover plate 10, thereby reducing the volume of the pumpingchamber 15. Consequently, the pressure pK(t) in the pumping chamber increases. A relative overpressure is generated in thepumping chamber 15, with pK(t) > pO. The overpressure in thepumping chamber 15 causes thesuction valve 19 to close, thus preventing a backflow of the fluid from the pumpingchamber 15 through theinlet opening 16 and into thesuction channel 20. Moreover, the overpressure in thepressure chamber 15 causes theoutlet valve 22 to open, thus enabling the fluid to flow out of the pumpingchamber 15 through theoutlet opening 17 and into theoutlet channel 24.
A further rotation of theeccentric disk 30 in the direction ofrotation 45 reduces the volume of the pumpingchamber 15 until thedrive device 29 has reached the top dead centre (cf.Fig. 2 ;Fig. 9 ;Fig. 16 ) again. - When the
eccentric disk 30 continues to rotate, the cycle repeats. - The following is a description of a pumping cycle during which the
spring element 33; 33a; 33b is flexible, thus being compressed to a maximum extent. This may be the case during the transport of an incompressible fluid and/or at a high speed of rotation of theshaft 28 and/or if thespring element 33; 33a; 33b is very soft. In the top dead centre position of thedrive device 29, thespring element 33; 33a; 33b is compressed to a maximum extent (Fig. 6 ;Fig. 13 ;Fig. 20 ). At this point of time, the pumpingchamber 15 has a minimum volume. A rotation of theeccentric disk 30 in the direction ofrotation 45 causes the force acting on thespring element 33; 33a; 33b to be reduced. This allows thespring element 33; 33a; 33b to relax, thus resulting in a relative displacement of thediaphragm connecting element 34; 34a; 34b in therod recess 36; 36a; 36b along thelongitudinal rod axis 50 until thespring element 33 or thestop collar 43a; 43b, respectively, comes to bear against the upper stops 37; 37a; 37b (Fig. 3 ;Fig. 10 ;Fig. 17 ). A further rotation of theeccentric disk 30 in the direction ofrotation 45 increases the distance between thediaphragm connecting element 34; 34a; 34b and thechamber cover plate 10. Due to thediaphragm connecting element 34; 34a; 34b being at least force-fitted to thediaphragm 9, the volume of thepump chamber 15 increases, this in turn causing the pumping chamber pressure pK(t) to be reduced to a low pressure in thepumping chamber 15, pK(t) < pI. The low pressure, if pK(t) > pI, causes thesuction valve 19 to open, thus enabling fluid to flow from thesuction channel 20 through theinlet opening 16 and into the pumpingchamber 15. The volume of the pumpingchamber 15 increases until thedrive device 29 has reached the bottom dead centre (Fig. 4 ;Fig. 11 ;Fig. 18 ). A further rotation of theeccentric disk 30 about the axis ofrotation 35 then reduces the distance along thelongitudinal rod axis 50 between thedrive device 29 and thediaphragm 9. Thereby, the force acting on thespring element 33; 33a; 33b increases, thus causing thediaphragm connecting element 34; 34a; 34b to be displaced in therod recess 36; 36a; 36b until the force of thespring element 33; 33a; 33b acting on thediaphragm connecting element 34; 34a; 34b prevents any further displacement, at the most until thediaphragm connecting element 34; 34a; 34b comes to bear against the lower stops 39; 39a; 39b or thespring mandrel 41, respectively (Fig. 7 ;Fig. 14 ;Fig. 21 ). - During a further rotation of the
eccentric disk 30 about the axis ofrotation 35, therod 32; 32a; 32b presses thediaphragm 9 in the direction towards thechamber cover plate 10 by means of thediaphragm connecting element 34; 34a; 34b, thus causing the volume of the pumpingchamber 15 to be reduced. This results in an increase of the pressure pK(t) in thepumping chamber 15, thus in turn, if pK(t) < pI, causing thesuction valve 19 to close, thus preventing a backflow of the fluid in a direction opposite to theinlet direction 21, i.e. from the pumpingchamber 15 through theinlet opening 16 and into thesuction channel 20. On the other hand, theoutlet valve 22 opens ifpK(t) > pO, thus enabling the fluid to flow out of the pumpingchamber 15 in thedischarge direction 25, i.e. through theoutlet opening 17 and into theoutlet channel 24. The volume of the pumpingchamber 15 reduces until thedrive device 29 has reached its top dead centre (Fig. 6 ;Fig. 13 ;Fig. 20 ). - When the
eccentric disk 30 continues to rotate, the cycle repeats. - Both the extent of deformation of the
spring element 33; 33a; 33b during a particular cycle and the particular phase of the cycle during which thediaphragm connecting element 34; 34a; 34b comes to bear against theupper stop 37; 37a; 37b and, as the case may be, against thelower stop 39; 39a; 39 are individually determined by, amongst other things, the compressibility of the fluid to be transported, the speed of rotation of theshaft 28 and the stiffness of thespring element 33; 33a; 33b. Force peaks on thedrive device 29, thediaphragm 9, the pumpingchamber 15 and thevalves diaphragm 9 being spring-mounted to thedrive device 29. A systematic selection of aspring element 33; 33a; 33b having corresponding damping properties enables thepositive displacement pump 1 to be specifically adapted to the expected operating conditions. Thereby, the suction capacity of thepositive displacement pump 1 may be optimized, depending on the fluid to be transported, while reducing the stress on thepositive displacement pump 1, in particular on the moving parts thereof. - Moreover, due to the displacement unit, i.e. the
diaphragm 9, being spring-mounted to thedrive device 29, the displacement volume of thepositive displacement pump 1 is automatically adapted to the compressibility of the fluid to be transported and to the drive speed of thedrive device 29. Generally, it can be determined that the less the displacement of thediaphragm connecting element 34; 34a; 34b in therod recess 36; 36a; 36b during a pumping cycle, i.e. the higher the compressibility of the fluid to be transported while using thesame spring element 33; 33a; 33b, or the stiffer thespring element 33; 33a; 33b while retaining the compressibility of the fluid to be transported, respectively, the larger the compression ratio of the fluid to be transported in thepumping chamber 15. On the other hand, a lower compressibility of the fluid to be transported leads to a higher stress on thespring element 33; 33a; 33b, thus generally resulting in an increased displacement of thediaphragm connecting element 34; 34a; 34b in therod recess 36; 36a; 36b and, consequently, in a reduced displacement volume. - Generally, it can be determined that a
softer spring element 33; 33a; 33b causes the compression ratio, and thus me displacement volume of thepositive displacement pump 1, to be reduced. - The following is a description, taken in conjunction with
Figs. 22 and23 , of another embodiment of the invention. Identical parts are referred to with the same reference numerals as used for the first embodiment to the description thereof reference is made. Parts that differ in design but have the same function are referred to with the same reference numerals with a subsequent c. The essential difference with respect to the previous embodiments is that therod 32c is elastic, thus comprising thespring element 33c. Therod 32c of thedrive device 29c is in particular made of plastics. Therefore, it is configured in a flexibly resilient manner. Therod 32c comprises arod drive area 46 which is concentric with theeccentric disk 30, two rodrecess side walls 47 extending parallel to thelongitudinal rod axis 50 and tangentially adjoining saidrod drive area 46 in an integral manner as well as rod stopwalls 48 which are integral with said rod-recess side walls 47. The upper rod stopwalls 48 are deformable with respect to the rod-recess side walls 47. Each of the upper rod stopwalls 48 has afree end 56 facing towards the through-opening 38c. When therod 32c is unstressed, the upper rod stopwalls 48 are substantially perpendicular to the rod-recess side walls 47. The rod-recess side walls 47 and the rod stopwalls 48 form thespring element 32c. The side of the upper rod stopwall 48 facing towards therod recess 36c forms theupper stop 37c for thediaphragm connecting element 34c. Thelower stop 39c is formed by the side of therod stop area 46 facing towards therod recess 36c. In this embodiment, the through-opening 38c disposed between the upper rod stopwalls 48 is advantageously configured as a longitudinal recess extending in the direction parallel to the axis ofrotation 35 along the entire depth of therod 32c. This results in an improved deformability of the upper rod stopwalls 48 with respect to the rod-recess side walls 47. Moreover, this provides for a simpler arrangement of thediaphragm connecting element 34c in therod 32 during the assembly. Thediaphragm connecting element 34c is slidable in particular over therod 32c. - The
diaphragm connecting element 34c is symmetric, in particular rotation-symmetric, with respect to thelongitudinal rod axis 50. It has arod connecting portion 49 which is integral with thecylindrical projection 42. Therod connecting portion 49 comprises an uppertransverse wall 52, a lowertransverse wall 53 and a connectingpiece 54 disposed therebetween. The uppertransverse wall 52 and the lowertransverse wall 53 define a bead-like groove 55. There may also be twogrooves 52 facing towards the rod-recess side walls 47. Thediaphragm connecting element 34c is relatively stiff. In particular, the modulus of elasticity thereof exceeds that of the material therod 32c is made of. This results in a particularly effective transmission of force from therod 32c to thediaphragm 9. Alternatively, thediaphragm connecting element 34c may also be elastic, thus contributing to the resilience of thediaphragm 9. Thediaphragm connecting element 34c is replaceable. It may be chosen in particular in accordance with the respective requirements. - In the unstressed state, for example when the
drive device 29c is situated at the bottom dead centre, as shown inFig. 23 , the side of the uppertransverse wall 52 facing towards thegroove 55 is positioned at an angle w1 with respect to a horizontal plane which is perpendicular to thelongitudinal rod axis 50. The angle w1 is in the range of 1° to 10°. Accordingly, in the unstressed state, for example in the top dead centre position of thedrive device 29c, as shown inFig. 22 , the side of the lowertransverse wall 53 facing towards thegroove 55 is positioned at an angle w2. The angle w2 is in the range of 0.5° to 5°. The angle w2 is in particular small enough to ensure a maximum deflection of thediaphragm 9 in the bottom dead centre position of thedrive device 29c. The following applies: w2 ≤ w1. Thegroove 55 thus widens outward. At its inner end, i.e. in the area of the connectingpiece 54, the configuration of thegroove 55 substantially corresponds to that of the free ends 56 of the upper rod stopwalls 48. Each of the upper rod stop walls 48.is in engagement with thegroove 55. The lowertransverse wall 53 of thediaphragm connecting element 34c is thus disposed in therod recess 36c. In the direction perpendicular to thelongitudinal rod axis 50, the dimensions thereof are thus smaller than those of therod recess 36c in this direction. Thus, a clearance is formed between the lowertransverse wall 53 of thediaphragm connecting element 34c and the rod-recess side walls 47. - On its side facing towards the
lower stop 39c, the lowertransverse wall 53 has a central recess in the shape of a cylindrical portion the curvature of which just corresponds to that of thelower stop 39c in the area of thelongitudinal rod axis 50. - In the top dead centre position, shown in
Fig. 22 , of thedrive device 29c, therod 32c is substantially mirror-symmetric to the centrallongitudinal plane 51. In this position, the dimension of the through-opening 38c in the direction perpendicular to the central longitudinal plane exceeds the dimension of the connectingpiece 34 of thediaphragm connecting element 34c in the same direction. Thediaphragm connecting element 34c is thus displaceable in the directions perpendicular to thelongitudinal rod axis 50 and perpendicular to the axis ofrotation 35. - The functioning of the
positive displacement pump 1 substantially corresponds to that of the previous embodiments to which reference is made. In this embodiment, however, the function of thespring element 33c is performed by theelastic rod 32c, in particular by the upper rod stopwalls 48. During the suction phase, therod 32c exerts a tensile force on thediaphragm connecting element 34c. Thereby, the upper rod stopwalls 48 increasingly come to bear against the lowertransverse wall 53 of thediaphragm connecting element 34. During this deformation, the angle, measured inside therod recess 36c, between the upper rod stopwalls 48 and each of the rod-recess side walls 47 adjacent thereto increases more and more until it has reached the value of 90° + w2. In this position shown inFig. 23 , at least part of the surface of the upper rod stopwall 48 bears against the side of the lowertransverse wall 53 facing towards thegroove 55. When theeccentric disk 30 performs a rotation in the direction ofrotation 45 during the discharge phase, thus reducing the volume of the pumpingchamber 15, therod 32c exerts a thrust force on thediaphragm connecting element 34c. Thereby, the upper rod stopwall 48 is increasingly pressed against the side of the uppertransverse wall 52 of thediaphragm connecting element 34c facing towards thegroove 55. The upper rod stopwall 48 is thus more and more pressed into therod recess 36c. Thereby, the angle between the upper rod stopwall 48 and each of the adjacent rod-recess side walls 47 is reduced to an angle of 90°-w1 at which at least part of the surface of the upper rod stopwall 48 bears against the uppertransverse wall 52. The respective sides of the uppertransverse wall 52 and the lowertransverse wall 53 of thediaphragm connecting element 34c facing towards thegroove 55 are inclined by the angles w1 or w2, respectively, thus ensuring that thediaphragm connecting element 34a gradually comes to bear against the upper rod stopwall 48. Due to the increasing contact surface between the upper rod stopwall 48 and the uppertransverse wall 52 or lowertransverse wall 53, respectively, the effective length of the spring arm of the upper rod stopwall 48, measured between the passage area and the rod-recess side wall 47, is more and more reduced, thus causing the spring action to increase steadily. Theelastic rod 32c is thus aspring element 33c providing a progressive damping effect. The damping behavior may be influenced by means of the exact configuration of the uppertransverse wall 52 or the lower transverse wall, respectively.
Claims (10)
- Positive displacement pump (1) for transporting a fluid comprisinga. a pumping chamber (15) with a variable volume (V), said pumping chamber (15) being at least partially delimited by a suction and displacement element;b. at least one suction channel (20) which is in flow connection with the pumping chamber (15) for sucking the fluid to be transported into the pumping chamber (15);c. at least one outlet channel (24) which is in flow connection with the pumping chamber (15) for discharging the fluid to be transported from the pumping chamber (15); andd. a drive device (29) for cyclically increasing and reducing the current volume (V) of the pumping chamber (15);e. with the drive device (29) being spring-mounted to the suction and displacement element by means of a spring element (33; 33a; 33b) so as to transmit force.
- Positive displacement pump (1) according to claim 1, characterized in that the spring element (33) is a leaf spring.
- Positive displacement pump (1) according to claim 1, characterized in that the spring element (33a) is a helical spring.
- Positive displacement pump (1) according to claim 1, characterized in that the spring element (33b) comprises an elastomer.
- Positive displacement pump (1) according to one of the preceding claims, characterized in that the spring element (33; 33a; 33b) is replaceable.
- Positive displacement pump (1) according to one of the preceding claims, characterized in that the suction and discharge element comprises a diaphragm (9).
- Positive displacement pump (1) according to one of the preceding claims, characterized in that the drive device (29) has a rod (32) which is supported on an eccentric disk (30) force-fitted to a drive shaft (28).
- Positive displacement pump (1) according to one of the preceding claims, characterized in that a suction valve (19) is provided in the direction of flow between the suction channel (20) and the pumping chamber (15).
- Positive displacement pump (1) according to one of the preceding claims, characterized in that an outlet valve (22) is provided in the direction of flow between the pumping chamber (15) and the outlet channel (24).
- Positive displacement pump (1) according to one of the preceding claims, characterized in that at least one of the valves (19, 22) comprises a valve flap.
Applications Claiming Priority (1)
Application Number | Priority Date | Filing Date | Title |
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DE102007005736A DE102007005736A1 (en) | 2007-01-31 | 2007-01-31 | Displacement pump for delivering a fluid with automatic adjustment to the compressibility of this fluid |
Publications (1)
Publication Number | Publication Date |
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EP1953387A2 true EP1953387A2 (en) | 2008-08-06 |
Family
ID=39327293
Family Applications (1)
Application Number | Title | Priority Date | Filing Date |
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EP08000832A Withdrawn EP1953387A2 (en) | 2007-01-31 | 2008-01-17 | Positive displacement pump for transporting a fluid with automatic adaptation to the compressibility of the fluid |
Country Status (4)
Country | Link |
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US (1) | US20080181800A1 (en) |
EP (1) | EP1953387A2 (en) |
CN (1) | CN101235813A (en) |
DE (1) | DE102007005736A1 (en) |
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WO2012016959A3 (en) * | 2010-08-04 | 2012-05-24 | Gardner Denver Thomas Gmbh | Pump |
WO2012016962A3 (en) * | 2010-08-04 | 2012-06-07 | Gardner Denver Thomas Gmbh | Pump |
WO2014174072A1 (en) * | 2013-04-26 | 2014-10-30 | Continental Teves Ag & Co. Ohg | Pump assembly |
KR101616964B1 (en) | 2014-06-16 | 2016-05-11 | 강소대 | Air Compressor using Crankshaft |
WO2016080058A1 (en) * | 2014-11-20 | 2016-05-26 | 株式会社Ibs | Diaphragm pump |
WO2023118581A1 (en) * | 2021-12-23 | 2023-06-29 | KNF Micro AG | Pump head for a diaphragm pump |
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CN101666308B (en) * | 2009-09-07 | 2011-01-12 | 无锡威孚力达催化净化器有限责任公司 | Reciprocating rubber diaphragm hydraulic pump |
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Family Cites Families (8)
Publication number | Priority date | Publication date | Assignee | Title |
---|---|---|---|---|
US2811929A (en) * | 1953-07-17 | 1957-11-05 | Gorman Rupp Co | Diaphragm pump |
US2895424A (en) * | 1955-09-13 | 1959-07-21 | Stewart Warner Corp | Constant pressure liquid pump |
US3947156A (en) * | 1972-03-08 | 1976-03-30 | Erich Becker | Diaphragm pump, particularly for the generation of vacuum |
JPS5172710A (en) * | 1974-12-20 | 1976-06-23 | Mitsubishi Motors Corp | |
DE4200838C2 (en) * | 1992-01-15 | 1994-12-22 | Knf Neuberger Gmbh | Pump with valves controlled by the medium |
DE4412668C2 (en) * | 1994-04-13 | 1998-12-03 | Knf Flodos Ag | pump |
DE19955688A1 (en) * | 1999-11-19 | 2001-05-23 | Leybold Vakuum Gmbh | Piston vacuum pump comprises a piston and a connecting rod which are joined to one another by means of an elastic unit |
DE10332642A1 (en) * | 2003-07-18 | 2005-02-03 | Leybold Vakuum Gmbh | Oscillating vacuum-displacement pump has spring-supported con-rod link to displacement body |
-
2007
- 2007-01-31 DE DE102007005736A patent/DE102007005736A1/en not_active Withdrawn
-
2008
- 2008-01-15 US US12/014,660 patent/US20080181800A1/en not_active Abandoned
- 2008-01-17 EP EP08000832A patent/EP1953387A2/en not_active Withdrawn
- 2008-01-31 CN CNA2008100071092A patent/CN101235813A/en active Pending
Cited By (7)
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WO2012016959A3 (en) * | 2010-08-04 | 2012-05-24 | Gardner Denver Thomas Gmbh | Pump |
WO2012016962A3 (en) * | 2010-08-04 | 2012-06-07 | Gardner Denver Thomas Gmbh | Pump |
WO2014174072A1 (en) * | 2013-04-26 | 2014-10-30 | Continental Teves Ag & Co. Ohg | Pump assembly |
US9784264B2 (en) | 2013-04-26 | 2017-10-10 | Continental Teves Ag & Co. Ohg | Pump assembly |
KR101616964B1 (en) | 2014-06-16 | 2016-05-11 | 강소대 | Air Compressor using Crankshaft |
WO2016080058A1 (en) * | 2014-11-20 | 2016-05-26 | 株式会社Ibs | Diaphragm pump |
WO2023118581A1 (en) * | 2021-12-23 | 2023-06-29 | KNF Micro AG | Pump head for a diaphragm pump |
Also Published As
Publication number | Publication date |
---|---|
US20080181800A1 (en) | 2008-07-31 |
DE102007005736A1 (en) | 2008-08-14 |
CN101235813A (en) | 2008-08-06 |
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