Patent Application
20240271611
This application claims priority to German Patent Application No. 10 2023 103 599.1, filed in Germany on Feb. 15, 2023, the entire contents of which are hereby incorporated herein by this reference.
The invention relates to a pump unit for transporting liquid and above all viscous materials such as adhesives and resins, and to a storage device which comprises a storage container for such materials which is continuously refilled, usually automatically, even during operation, and from which these materials have to be pumped to a downstream consumer by means of such a pump.
In the industry, pasty materials in particular—e.g. potting compounds for moisture-proof encapsulation of electronic circuits, or adhesives for tightly bonding components together—are often applied to the corresponding components by means of automated dispensing processes via automatic dispensing machines as consumers, and must therefore be constantly supplied with the pasty material.
For this purpose, such a consumer is connected, via lines, to the storage device, in the usually pot-shaped storage container of which the corresponding material is located. A pump unit which effects the transportation of this viscous material is arranged in the line that leads from a usually low-lying removal opening of this storage container to the consumer.
One problem is that these materials often contain abrasive solids in finely dispersed form, for which reason certain pump designs in which one surface of a pump element slides tightly along a stationary surface, such as continuously operating worm pumps, are not suitable for this purpose, since the abrasive solids can get between these surfaces and cause rapid wear there.
Instead, pumps are frequently used in which the pump element comprises an elastic element which, although coming into connection with the abrasive material on one side, does not have to be moved tightly along another surface. The most common design is a diaphragm pump, which also has the advantage that it can be manufactured at low cost.
This is because transporting material to the consumer does not necessarily require a very precise volume to be maintained with each pump stroke, but simply a sufficient, preferably constant, pressure must always be present in the supply line to the consumer and thus in the outlet opening of the feed pump so that the consumer is sufficiently supplied with material at all times.
Since a diaphragm pump does not provide a continuous delivery stream, two diaphragm pumps are often operated alternatingly, are usually connected to the same storage container via separate connections and are controlled in such a way that one diaphragm pump is performing a working stroke, i.e. discharging material towards the consumer, while the other diaphragm pump is performing a return stroke, i.e. its pump chamber is being filled with new material from the storage container.
The necessary drive of the feed diaphragm transverse to its main plane can be realized by differently designed feed pump drives. It is known to use a further, pneumatically operated diaphragm unit or a likewise pneumatically operated working cylinder unit for this purpose, since in the event of leaks such pneumatic units do not result in contamination of the material.
However, in order to apply the high drive force necessary, especially in the case of very pasty materials, a pneumatically operated feed pump drive has to be dimensioned relatively large, which is disadvantageous due to the space available for such a pump unit often being very limited in practice.
The compressibility of the pressure medium in a pneumatically operated drive unit is also disadvantageous.
It is therefore the object of the invention to provide a pump unit—especially for the storage device described—which is compact and inexpensive to manufacture.
In addition, it is the object of the invention to provide a method for operating such a pump unit and in particular its feed pump drive, which method makes a compact design possible.
This object is achieved by the features of claims 1, 14, and 17. Advantageous embodiments result from the subclaims.
A generic pump unit for pasty material comprises a feed pump which has a pump element which can move relative to the feed pump housing, as well as a feed pump drive in the form of a drive working cylinder for this pump element.
According to the invention, the drive working cylinder is a hydraulic cylinder, for which reason at least the working chamber on the rear side, facing away from the pump element, of the drive piston of the drive working cylinder has a hydraulic connection.
This is understood to be the working chamber that moves the pump element in the ejection direction when pressure is applied and the drive piston is correspondingly displaced, also referred to in the present application as the rear-side or rear working chamber of the drive working cylinder, even if, due to a reversal of direction in the operative connection between the drive working cylinder and pump element, this working chamber is not located on the rear side of the drive piston facing away from the pump element from a geometric point of view.
On the one hand, this allows the effective surface of the hydraulic piston in the hydraulic cylinder to be kept small, since high pressures can be applied more easily by means of a hydraulic medium than by means of a gas, so that even the movement of the feed diaphragm is thus faster.
Furthermore, due to the incompressibility of the hydraulic medium, the movement path of the hydraulic piston of the pump drive and thus of the pump element, in particular its movement path in relation to the elapsed movement time, can be controlled more precisely than in the case of a pneumatic cylinder.
Preferably, the other working chamber, i.e. the front-side or front working chamber, of the drive working cylinder also has a connection for a pressure medium, be it a hydraulic medium or compressed air, so that the pump element can also be pressurized in the direction of the drawing of material in the feed pump, which accelerates the operation of the pump unit.
In particular, the drive working cylinder, preferably its piston rod, is mechanically fixedly coupled to the elastic element, in particular to the feed diaphragm, via a drive plunger.
Furthermore, the drive chamber of the feed pump facing away from the feed chamber in relation to the pump element can also have a hydraulic connection, so that in particular the same pressure can be applied there as in one of the two working chambers of the hydraulic pump itself, which additionally increases the acceleration and speed of the pump element.
This can be realized in a simple manner by a connecting line, which can be closed in particular by a valve, between the drive chamber of the feed pump and the at least one working chamber of the hydraulic cylinder.
A pressure sensor is preferably present at least in the working chamber of the working cylinder unit that can be charged with hydraulic medium, in order to be able to monitor the correct application of pressure medium to the working piston.
The pump element preferably comprises at least one elastic element, the elastic element preferably itself being the pump element, which during pumping operation is only in contact on one side with the material to be conveyed.
This elastic element should be a substantially flat diaphragm, which means that the extension of the diaphragm transverse, in particular perpendicular, to its main plane, in which it has its greatest extension, is at most 50%, better at most 40%, better at most 30%, better at most 20% of the maximum extension along its main plane.
Such a pump unit preferably also comprises a controller, usually an electronic controller, which controls at least all moving parts of the pump unit.
There are different forms of pump that comprise an elastic element as part of the pump element:
On the one hand, a bellows pump in which a pump piston is axially movable in a pump housing but the pump piston does not lie tightly against the cylinder wall with its outer circumference—whether via seals or piston rings—and move along this wall, but rather ends radially at a distance from the inner circumferential wall of the cylinder, wherein a sleeve-shaped, elastic bag, usually a bellows, is tightly attached with its one annular end edge to the outer circumference of the pump piston and with its other annular end edge to the pump housing.
Another design is a so-called diaphragm pump, in which an elastic, approximately plate-shaped diaphragm divides the interior of the pump housing—usually formed by two bell-shaped or cup-shaped housing parts with the open sides tightly fastened against each other—into a feed chamber and a working chamber, and is tightly fastened around its outer edge against the pump housing, for example between the two housing halves which are pressed against each other, usually screwed together.
By moving the diaphragm transversely to its main plane the feed chamber is alternately enlarged and made smaller, so that, by means of corresponding inlet and outlet valves, when the volume of the feed chamber, which at its maximum volume is filled with the material, is reduced by means of the diaphragm the material contained therein is pressed out through an outlet opening and is conveyed to the consumer, and when its volume is increased it is filled with material through the inlet opening.
The diaphragm pump design in particular, which is at the foreground of the present invention, is very simple and inexpensive to manufacture, since the individual components for this purpose are inexpensive to manufacture due to having only a few and, moreover, flat fitting surfaces.
In addition to the continuous main part of the diaphragm that separates the interior of the pump housing, the diaphragm preferably has a concentric, annular diaphragm extension on the drive side of the diaphragm, which extension is in particular made in one piece with the main part of the diaphragm. The radially outer edge of the annular diaphragm extension merges into the continuous part of the diaphragm, and its free, radially inner edge projects therefrom and is resilient in the direction of movement in relation to the continuous main part of the diaphragm.
The diaphragm extension is preferably arranged in a circumferentially annular fashion between the outer edge and the central region of the main part of the diaphragm.
A mushroom-shaped diaphragm support is located as a tension plate with the outer circumferential edge region of its head in the intermediate space between the continuous and the annular part of the diaphragm, and the stem of the mushroom shape extends away from the diaphragm through the central opening of the annular extension and is detachably connected, for example screwed, to the piston rod or directly to the piston of the hydraulic cylinder.
As a result, the diaphragm can be not only pushed but also pulled. The head of the diaphragm support is either seated only with a positive fit between the two parts of the diaphragm or is firmly connected to one or both of these parts, for example glued.
The effective surface that can be acted on of the drive piston of the working cylinder is preferably hardly larger, at most 20%, better at most only 10% larger, preferably equal to or at least 10% smaller, better at least 20% smaller, than the effective surface of the diaphragm of the diaphragm feed pump.
As a result, low pressures of the drive medium already suffice for operating the hydraulic drive working cylinder.
The drive chamber of the feed pump can also have a pressure connection and negative pressure can therefore, for example, be applied, preferably the same negative pressure that usually prevails in the storage container to be emptied.
This ensures that during the return stroke the diaphragm can be actively moved into the fully retracted filling position and that the diaphragm is not sucked in the direction of the inlet opening in the region of the inlet opening by a pressure difference prevailing there.
In order to be able to further increase the force with which the ejection takes place, it can also be provided that the drive chamber of the diaphragm pump, i.e. the feed pump, can also be acted upon by hydraulic medium and therefore has a hydraulic connection, in particular with the same pressure, or a pressure adjustable in relation thereto, as the working chamber of the hydraulic cylinder facing away from the feed pump, for which purpose there is then preferably a connecting line in between, in particular with a proportional valve in its course.
A position sensor is preferably provided to monitor the position of the feed pump drive or of the diaphragm in the axial direction, at least with regard to reaching the two end positions, preferably over their entire movement path.
A heating device, in particular in the form of electrical heating coils for a heated liquid heating medium or electrical lines, can also be provided upstream of the feed pump housing or within the feed pump housing in order to heat the material to be pumped and thus to thin it and make it more pumpable. Conversely, in individual applications, a cooling device may also be necessary which can comprise pipes for a cooled liquid coolant.
A leakage sensor, in particular a liquid sensor, is preferably arranged in the drive chamber of the feed pump, which detects material entering the drive chamber in the event of a leak, such as a tear in the diaphragm, and reports this to the controller, which thereupon emits at least one alarm signal. The use of a liquid sensor only makes sense when no hydraulic medium is provided in the drive chamber.
With regard to the storage device, which comprises at least one pump unit in addition to the storage container for the material to be conveyed, this object is achieved in that the pump unit is designed according to one of the preceding claims.
Here the storage device preferably comprises two such pump units, which can be driven, for example, counter-synchronously in order to ensure a quasi-continuous feed of the material into the common outlet line to the consumer.
However, the two pump units can preferably be controlled independently of each other, so that temporal overlaps between the return stroke of the one pump unit and the working stroke of the other pump unit, or a time interval between them, can also be achieved.
The tightly sealed storage container is preferably pressurized with a negative pressure to prevent air from mixing into the material in the storage container, especially if this container is equipped with a mixer.
The air chamber of the storage container is preferably then connected to the drive chamber of the feed pump—of course, only if the drive chamber is not connected to the hydraulic circuit—and this connection can be selectively opened and closed via a valve.
As a result, the same pressure prevails on both sides of the diaphragm in the feed pump, so that when the feed pump is being filled, the diaphragm is brought into the optimally close end position to the housing on the drive side and a maximum pump volume is achieved, even without having hydraulic medium on the drive side of the diaphragm or of the bellows, which, in the event of a tear in the elastic element, such as the diaphragm, results in a long downtime and high resulting costs due to the mixing of hydraulic medium and the material to be pumped.
With regard to the method for operating such a pump unit, in particular in such a storage device, the existing object is achieved by the feed pump drive in the form of a working cylinder unit being operated at least partially hydraulically.
The working piston is hydraulically acted upon at least in the direction in which the working cylinder unit moves the pump element in the ejection direction.
In the opposite direction, it can be acted on hydraulically or pneumatically, in each case alternating with being acted on in the ejection direction.
The application of a pressure medium even in the opposite direction increases the speed of movement of the pump element.
The axial position of a moving, to be monitored element of the pump unit, in particular
In most cases, the drive chamber of the diaphragm feed pump is also pressurized with negative pressure, in particular with the same negative pressure as the air chamber of the storage container, in particular as soon as the ejection movement of the drive plunger has ended, or permanently, in order to avoid deformations of the diaphragm in the direction of the material inlet opening caused by negative pressure on one side.
The inlet valve is preferably closed as soon as the position sensor signals that the end position of the diaphragm of the feed pump has been reached in the filling position, in order to ensure that no material can be pushed back into the storage container during the subsequent ejection.
If a leakage sensor, in particular a liquid sensor, is present, the controller can report the entry of liquid into the drive chamber when a corresponding signal is received and can emit an alarm signal so that the diaphragm pump is repaired, in particular the diaphragm is replaced, or the entire pump unit is replaced by a new one.
This minimizes the duration of an interruption in operation of the storage device, especially as only the actively controllable inlet valve of the corresponding pump unit needs to be closed for this, and the pump unit can be disconnected from its connections and removed after a final feed stroke has been completed.
Embodiments in accordance with the invention are described in more detail below by way of example. In the figures:
The structure of a pump unit 1 according to the invention can best be seen in the sectional view in
The pump unit 1 consists of a feed pump 1.1 in the form of a diaphragm pump, and a diaphragm 4 serving as the pump element 3 in the direction of movement 10, a feed pump drive 8 coaxially upstream of this diaphragm pump and connected to it in the form of a hydraulically operated working cylinder unit 1.2, i.e. a hydraulic cylinder 8.
Both the diaphragm 4 and the drive piston 1.2a coaxial thereto of the working cylinder unit 1.2 are rotationally symmetrical, viewed in the direction of the longitudinal central axis 1′, which is perpendicular to the main plane 3′, which here runs approximately horizontally, of the diaphragm 4 and of the drive piston 1.2a and at the same time is the direction of movement of the drive piston 1.2a, and in the installed state is often identical to the vertical 11.
The feed chamber 1.1a has an inlet opening 5a in the upper region, via which the material M can flow into the feed chamber 1.1a when the inlet valve 5 arranged in or at the inlet opening 5a is open, the outlet valve 6 then generally being closed.
In the upper region, the feed chamber 1.1a also has an outlet opening 6a, in or at which an outlet valve 6 is arranged, so that material M can flow out of this outlet opening 6a when this outlet valve 6 is open, the inlet valve 5 then generally being closed.
In this way, the feed chamber 1.1a is filled with material M when the diaphragm 4 moves away from the inlet opening 5a (filling stroke) and the material M in the feed chamber 1.1a is ejected into the outlet opening 6a when the diaphragm 4 moves towards the outlet opening 6a (feed stroke), generally being controlled by a controller 1*.
The feed pump 1.1 is driven, i.e. its diaphragm 4 is moved alternately back and forth transversely to its main plane 4′, by means of a drive plunger 9 engaging in the center of the diaphragm 4 on its rear side, i.e. from the drive chamber 1.1b.
The feed pump drive 8 in the form of a hydraulic cylinder 8 comprises a drive piston 1.2a, which can move back and forth in a drive cylinder 1.2b between two end positions, in particular two stops, preferably in the same direction of movement in which the diaphragm 4 of the diaphragm feed pump 1.1 coupled to the feed pump drive 8 can also move.
However, the effective surface of the drive piston 1.2a is selected to be barely, at most 20%, better at most only 10% larger, preferably the same or at least 10%, better at least 20%, smaller than that of the diaphragm 4, in order to make possible a compact design of the drive cylinder and thus of the entire pump unit.
The hydraulic cylinder 8 has a hydraulic connection 13 at least as shown on the pressure side of the drive piston 1.2a facing away from the diaphragm 4 and the feed pump 1.1 in the working chamber of the drive cylinder 1.2b. However, it will generally also have such a hydraulic connection on the other side of the drive piston 1.2a, the pull side, in order to be able to actively and thus more quickly pull the diaphragm 4 back from the inlet opening 5a and accelerate the filling of the feed pump 1.1. For this purpose, the two hydraulic connections 13 can be supplied from the same pressure medium source and selectively fed to one of the two working chambers of the hydraulic cylinder via a directional control valve 20.
The working chamber 1.1b of the feed pump 1.1 can also have a hydraulic connection in that it is preferably connected to the working chamber of the hydraulic pump remote from the diaphragm pump via a connecting line 19 and optionally a proportional valve 18.
A proportional valve 16 is preferably connected upstream of the, in particular each, hydraulic connection 13, which valve can be connected to the controller 1* of the pump unit 1 and can be controlled by it, as described above.
For this purpose, constant knowledge of the position of the drive piston 1.2a is essential, for which reason a position sensor 17 is arranged in the base of the drive cylinder 1.2b, preferably in the form of a distance sensor, which measures the distance of the drive piston 1.2a from the base of the cylinder 1.2b and reports it to the controller 1*. This sensor on the sensor cover (in the center at the bottom). This sensor measures the position of the piston via the conical surface in the piston.
The pump unit 1 preferably has a pressure connection 12 (pressure connection 12 in
A leakage sensor 15 is preferably arranged in the side of the diaphragm 3 facing away from the feed chamber 1.1a, the drive chamber 1.1b, which sensor detects material M that has penetrated there, which occurs at most in the event of a leak in the diaphragm 3 itself or in its circumferential clamping. As a rule, such a leakage sensor 15 is a liquid sensor, which however is also only useful when this drive chamber 1.1b of the feed pumps 1.1 does not have a hydraulic connection.
The drive piston 1.2a is connected to the diaphragm 3 via a drive plunger 9, which is arranged centrally, i.e. running along the axial direction 10, the direction of movement, and is attached to the diaphragm 3 on its rear side, i.e. the side of the drive chamber 1.1b.
There can preferably also be a pressure sensor 16 in this drive chamber 1.1b, which sensor can be in particular designed to be functionally combined with the leakage sensor.
The drive plunger 9 can be designed in multiple parts:
On the one hand, it comprises the shaft 9.1, which substantially bridges the distance from the drive piston 1.2a to the diaphragm 4, as well as a pressure plate 9.2, which is located at the end of the shaft 9.1 at the diaphragm side and abuts the diaphragm 4 with a large contact surface 9a (9.a is not shown in the drawing).
Viewed in cross-section, the diaphragm 4 has, in addition to the central region 4.2 which is continuous within the circumferential clamping of the in particular covered edge 4.1, an annular extension 4.4 to or in the drive chamber 1.1b, wherein the inner circumference of the extension 4.3 ends freely and its outer circumference is integrally connected to the rear side of the continuous main part 4.3 of the diaphragm, in particular to the central region 4.2.
In the intermediate space between the main part 4.3, continuous from one edge to the other, and the extension 4.4, there is a tension plate 9.3 which, on its rear side, has a centrally situated stem which protrudes through the opening of the extension 4.4 in the direction of the shaft 9.1 and is connected thereto, preferably screwed into it.
The tension plate 9.3 is used to be able to pull back the diaphragm 4 with a large engagement surface in the form of the extension 4.1 in the event of a rapid backward movement of the drive piston 1.2a caused by compressed air (the compressed air option for the backward movement needs to be described in more detail).
As can be seen, in the central position of the drive piston 1.2a according to
When the drive piston 1.2a is at the end of the feed stroke, in particular abutting an axial stop of the feed pump housing 2 formed on the drive cylinder 1.2b as shown in
In the other end position according to
The inlet valve 5 and the outlet valve 6 in
Instead of having an identical design to the inlet valve 5, the outlet valve 6 can also be designed as a simple non-return valve 7, as shown in
For this reason, the outlet valve 6 should preferably be arranged with the valve seat 7.2 pointing upwards within the storage device 100 and preferably lying lower than the storage container 101 (a lower situation is not absolutely necessary).
This pump unit is used for the A2xx and not for the LP804.
This pot is filled or can be refilled with material M via an inlet opening 103 and has one or two outlet openings 102 in the base 108, to each of which a pump unit 1 is connected with its inlet nozzle.
The at least one inlet opening 103 is here positioned in such a way that the material M falling downwards from it meets a truncated-conical drainage surface 110a of a drainage body 110 and flows downwards and radially outwards along it to its lower drip edge 109 in a thin layer, thereby degassing it.
Since the wall 107 of the pot 101.1 is not vertical, but is inclined radially upwards and outwards, and the drip edge 109 is located in the upper region of the storage container 101 near the inner surface 107a of the wall 107, the material M flows downwards from the drip edge 109 and meets the inner surface 107a of the wall 107, where it continues to run downwards as a thin layer and continues to degas.
The one or two pump units 1 are arranged so as to be situated horizontally with the diaphragm planes 3′ of the feed pumps 1.1.
The storage container 101 is usually under negative pressure, in that in the lid 101.2, in addition to the inlet opening 103 there is also a negative pressure connection 104 which is coupled to a negative pressure pump 105. The interior of the storage container 101 is connected to the housing cavity of the feed pump 1.1 via a connecting line 113.
The storage container 101 often comprises a stirrer 106, which prevents sedimentation of heavy components of the material M by rotating around the longitudinal central axis 101′.
The motor 111 which drives the stirrer 106 is mounted on the upper side of the lid 101.2 and its motor-driven shaft 111a extends through this lid 101.2 in a sealed manner into the interior of the pot 101.1 and is connected to the upper ends of the stirrer blades 112a,b which rotate in the pot 101.1.
A rod-shaped fill-level sensor 114 extends upward from the base 108.
The drainage body 110 can be mounted in a stationary manner on the lid 101.2 or can be fastened to it so as to co-rotate with the stirrer 106, preferably at the upper region of the stirrer blades 112a-c.
Furthermore, a heating device 107 in the form of, for example, heating wires may be provided in the storage container 101, in particular in its wall, in order to heat the material M and thereby to thin it.
The controller 100* of the storage device 100 can also contain the controller 1* of the at least one pump unit 1.
| Number | Date | Country | Kind |
|---|---|---|---|
| 10 2023 103 599.1 | Feb 2023 | DE | national |
