Patent Application
20140161644
The invention relates to a diaphragm pump, especially for example to a diaphragm pump having a removable or disposable pump unit cooperating with a drive unit.
A diaphragm pump is a type of pump in which a driven diaphragm, sometimes known as a membrane, is moved to increase and decrease the volume of a chamber. The chamber is connected to an inlet one-way valve and an outlet one-way valve.
US 2009/0035152 describes a fluid pump with a disposable element, the disposable element including the chamber. In one embodiment, the disposable element includes a flexible membrane that forms not just the membrane adjacent to the chamber but forms the valves on the inlet and outlet. The valves are not automatic one-way valves but are driven by solenoids to be open and closed.
Where disposable pumps are used, the cost of the disposable element is critical. There is therefore a need for a pump element that is simple and easy to manufacture.
According to a first aspect of the invention, there is provided a disposable pump unit with detent extensions for engaging in a snap fit with a drive unit to form a snap fit unit and a gripping part integrally formed on the flexible wall arranged to mate with the piston (18) when the disposable pump unit is engaged in a snap fit with the drive unit.
By arranging for a separate disposable unit which can simply snap fit on a drive part embodiments of the invention can automatically align and mate the piston with the gripping part mounting of the disposable unit is made easy and quick.
In one arrangement, the disposable pump unit is formed of an outer unit, an inner unit and a diaphragm unit between the outer unit and the inner unit. The internal chamber may be defined in the outer unit and the flexible wall and gripping part may be integral parts of the diaphragm unit. By making the disposable pump unit out of only three components manufacture is simplified.
Each of the inlet and outlet one-way valves may have a tongue integrally formed in the diaphragm unit. This integrally forms the moving part of the valves without requiring an additional component.
The detent extensions may be legs extending from the outer unit past the inner unit for engagement with the drive unit. Such extended legs provide a convenient attachment mechanism.
In another aspect, the invention relates to a two-part pump with a disposable pump unit and a drive unit with a motor for driving the disposable pump unit.
The drive unit may include holes for engagement with the detent extensions of the disposable pump unit.
In embodiments, the drive unit may include a recess and the disposable pump unit may include a boss having an opening, the boss being in engagement with the recess when the detent extensions grip the disposable pump unit to locate the disposable pump unit on the drive unit. In this position, the piston unit may pass through the opening. The accuracy of mating can be addressed.
In a further aspect, the invention relates to a disposable pump unit for engagement with a drive unit.
For a better understanding of the invention, embodiments of the invention will be described, purely by way of example, with reference to the accompanying drawings, in which:
The drawings are schematic and the exact sizes and shapes of various components may vary. The description of the components is not necessarily repeated for different figures.
Referring to
In use, the motor is driven to rotate which rotates drive shaft 30 and which causes reciprocating motion of the drive piston 18 by virtue of cam 32.
The disposable pump unit 4 is manufactured from only three plastics mouldings, namely a outer unit 50, a inner unit 70, and a diaphragm sheet 60 which is sandwiched between the outer unit 50 and inner unit 70 in the disposable pump unit. These units are illustrated separately in
Legs 10 depend from the disposable pump unit 4 and have a detent lug 12 on the ends. The legs 10 are flexible and are formed in the outer unit 50 and extend part the inner unit 70 towards the drive unit 6. Holes 16 are provided through fixing plate 14 on the drive unit 6 for engagement with the legs 10. In use, when the disposable pump unit 4 is fitted onto the drive unit 6, the detent lug 12 passes through the hole 16 in the fixing plate 14 and the detent lug 12 engages with the fixing plate 14. This forms a secure fit. To remove the disposable pump unit 4, the user compresses the legs 10 to disengage the detent lug 12 from plate 14 and removes the disposable pump unit 4.
The drive unit 6 also contains a drive piston 18 which engages with a gripping part 20 in the disposable pump unit as will be described later.
Referring to
Referring to
The outer unit 50 and inner unit 70 are made of less-flexible resilient plastics so as to retain their shape when mated with the inner unit.
The pump inlet 24 is connected to inlet opening 78 in the inner unit 70 which faces the inlet valve chamber 52 and inlet tongue 64.
The outlet valve 36 operates as follows. Fluid in the pump can flow outwards along outlet channel 54 to end 58 where it forces the outlet tongue 66 to bend away from the end 58 of the outlet channel 56 into extended recess 74 to open the outlet valve 36. The fluid can then pass to pump outlet 26. This allows fluid to exit the pump chamber 22. However, fluid cannot return since in the event of flow in the other direction the outlet tongue 66 is urged against the end 58 of the outlet channel to seal the outlet channel 56.
The inlet valve 34 operates in a similar way but in the reverse direction. Fluid flows in from inlet 24 through inlet opening 78. The inlet tongue 64 is urged away from the inlet opening into inlet valve chamber 52 and from there the fluid flows along inlet channel 54 into chamber 22. In reverse, however, fluid cannot flow out along inlet channel 54 since the fluid urges the inlet tongue 64 against inlet opening 78.
Thus, in use, the motor 28 causes reciprocating motion of piston 18 which urges the diaphragm 62 to reduce the size of the chamber and then increase it. As the chamber size increases, fluid is drawn in through the pump inlet 24 and inlet valve 34 and then as the chamber size decreased the fluid is expelled through outlet valve 36 and pump outlet 36.
Some further design features improve operation of the unit and render it easier to manufacture.
The shape of the end of the piston unit 18 contains a chamfered edge lip 38 around its circumference. This makes it easy for the gripping part 20 to be mated with the end of the piston unit.
The formation of the disposable pump unit 4 using only three pieces, each of which can be separately moulded, allows for the disposable pump unit to be manufactured relatively cheaply.
Moreover, the location of the channels and their design has been designed to allow the pieces to be moulded as simply as possible. Only the pump inlet 24 and pump outlet 26 require internal channels, i.e. channels not open at outer or bottom—the rest of the unit simply is a single shape with recesses. This minimises the need for side arms in the injection moulding apparatus which greatly increases the density of mouldings that can be moulded in a single moulding operation.
Further aspects of the design allow the two parts to be joined together with minimal rattles in the assembled pump. In particular, a recess 80 surrounds the piston unit 18 at the outer of the drive unit 6 and a boss 82 is provided on the underside of the inner unit 70 to engage with this recess. The boss 82 is on rim 84 which defines an internal mounting chamber 86 which holds the gripping part 20. The boss 82 accordingly has opening 88 through which the piston unit 18 can pass to reach the gripping part 20. The recess 80 is slightly less deep than the height of the boss 82, for example 0.1 mm to 1 mm. This means that the boss 82 is urged slightly inwards when the two parts are mated, since the plastics used in the inner unit are slightly flexible as well as resilient which allows rim 84 to bend slightly. This resilience urges the boss 82 and recess 80 together which reduces rattling when the pump is operated in use.
Further, the design allows the piston unit 18 to automatically engage the gripping part 20 when the legs 10 are passed through holes 16 in the plate 14 without requiring additional alignment. Full mating of piston unit 18 and gripping part 20 may occur after the motor has been switched on to fully insert piston unit 18 inside gripping part 20.
Thus, the complete design uses only three plastics mouldings for the disposable pump unit and yet fully implements the chamber 22, and the inlet and outlet valves 34, 36 of a diaphragm pump. The disposable pump unit of the pump is therefore relatively inexpensive.
The pump is suitable for any application where a disposable pump may be used. In particular, the pump may be used for medical applications.
Referring to
In an alternative embodiment, not shown, a steel shim disc is bonded to the bottom of the pump diaphragm as the gripping part, and a magnet provided on the end of piston unit 18 for magnetic coupling to the gripping part.
Those skilled in the art will realise that the exact design as described above may be varied as required. For example, the pump inlet 24 and pump outlet 26 are both provided on the inner part 70 of the disposable pump unit 4, which requires the inlet and outlet valves 34,36 to operate in different directions. Alternative embodiments can provide one of the pump inlet 24 and pump outlet 26 on the outer part 50 and the other on the bottom part 70, or indeed both on the outer part 50, with different arrangements of channels and valves.
| Number | Date | Country | Kind |
|---|---|---|---|
| 1209238.3 | May 2012 | GB | national |
