| JP2000088265 | BATHROOM HEATING DEVICE |
| JPS52139250 | APPARATUS FOR CIRCULATING WARM WATER |
| JPH09101062 | THERMAL ENERGY SUPPLY SYSTEM FOR CONSUMER |
HENDERSON ALAN RODNEY (GB)
| WO1991018246A1 | 1991-11-28 |
| GB1402471A | 1975-08-06 |
CLAIMS
1. A pump assembly comprising a first pumping device having a manifold with an impeller drivable therein to pump fluid from a first supply source to an outlet of the manifold, the manifold further comprising an inlet for receiving fluid from a second supply source for combining with the fluid from the first supply source, the action of the impeller serving to enhance mixing together of the fluids in the manifold.
2. A pump assembly as claimed in claim 1 wherein the inlet for feeding fluid from the second supply source into the manifold is arranged generally tangentially with respect to the impeller.
3. A pump assembly as claimed in claim 1 or claim 2 wherein the outlet from the manifold is arranged generally tangentially with respect to the impeller.
4. A pump assembly as claimed in claim 3 wherein said inlet and said outlet are arranged generally in alignment with each other.
5. A pump assembly as claimed in any preceding claim wherein said outlet from the manifold has a larger bore than said inlet into the manifold.
6. A pump assembly as claimed in any preceding claim wherein fluid from the second supply source is delivered to said inlet by means of a second pump.
7. A pump assembly as claimed in claim 6 wherein said first and second pumps are arranged side by side with their respective manifolds being formed as part of a single unit.
8. A pump assembly as claimed in claim 7 wherein said second pump is an impeller-driven pump.
9. A pump assembly as claimed in any preceding claim and further comprising means for adjusting the presume and/or flow rate of the fluid from at least one of the first and second supply sources whereby to vary the resulting fluid mixture.
10. A pump assembly as claimed in claim 9 wherein said adjusting means comprises means for controlling the speed of the or one of the or both pumps.
11. A pump assembly as claimed in any preceding claim and further comprising a sensor in the outlet from the manifold of the first pump for detecting the temperature of the mixed fluid.
12. A pump assembly as claimed in claim 11 and further comprising means for controlling the fluid mixture in response to signals from the sensor.
13. A pump assembly substantially as herein described with reference to the accompanying drawings.
14. A fluid supply system comprising a pump assembly as claimed in any preceding claim. |
Improvements in fluid pumping systems
This invention relates to fluid pumping systems and in particular, though not exclusively, to systems for the supply of water for domestic use.
In domestic water supply systems, for example for supplying water to appliances such as showers or underfloor heating systems, there is a need to be able to control the water temperature. There are various ways of achieving this, typically comprising mixing together separately pumped hot and cold water streams. Such conventional arrangements can tend not to provide very accurate control and/or can suffer from loss of pressure and/or flow rate.
The present invention provides a pump assembly comprising a first pumping device having a manifold with an impeller drivable therein to pump fluid from a first supply source to an outlet of the manifold, the manifold further comprising an inlet for receiving fluid from a second supply source for combining with the fluid from the first supply source, the action of the impeller serving to enhance mixing together of the fluids in the manifold.
By way of example, embodiments of the present invention will now be described with reference to the accompanying drawing, in which:
Figure 1 is a schematic illustration of a pump assembly according to the invention.
The pump assembly seen in Figure 1 comprises two pumps 10 and 11, one of which is connected to a cold water supply and the other of which is connected to a hot water supply via respective inlets 12 and 13. It is not important which way round the hot and cold supplies are connected.
It will be seen that pump 11 has an outlet 15 which is connected to the manifold 16 of pump 10. Pump 11 thus acts as a feed to pump 10 and pump 10 acts to combine and mix together the two water supplies, as will be described.
The mixer pump 10 is of an impeller-driven type, such as the centrifugal pump shown in Figure 1, ie it has a rotary impeller 14. Other kinds of impeller-driven pump could be used instead, for example a regenerative (turbine) pump, albeit with a somewhat differently configured feeder stream to that seen in Figure 1.
In this embodiment, the feeder pump 11 is also of the impeller-driven variety. It would be possible, however, for the feeder pump to be of a different variety, or even for the feed water to the mixer pump not to be supplied by a pump at all, but from a header tank or from the mains, for example.
By arranging to combine the flows of hot and cold water in the manifold 16 of the mixer pump 11, it has been found that a relatively thorough mixing of the hot and cold water streams can be achieved. It is understood that the impeller 14 contributes to the mixing process in that it helps to break up what might otherwise be discrete laminar streams of unmixed hot and cold water. Control of the mixing process is enhanced if the two flows are arranged to be at substantially equal pressure when they are combined.
It will be seen that the outlet 15 from the feeder pump 11 is arranged here to enter the manifold 16 of the mixer pump 10 tangentially with respect to the impeller 14. It will also be seen that the outlet 12 from the feeder pump 11 here is arranged to be in line with the outlet 18 from the mixer pump 10 (which is also arranged tangentially with respect to the impeller 14). These configurations are not essential, although they have been found to produce a satisfactory mixing process. Also, the arrangement is convenient in terms of
design, because it enables the manifolds of both pumps to be produced as part of a single unit, indicated in Figure 1 by the dotted outline 17.
The outlet 18 from the manifold 16 of the mixer pump 10 is of a larger bore than the outlet 15 from the feeder pump 11. This is to allow for the greater flow which results from the combination of the flows from the two sources.
A sensor 19 situated in the outlet 18 of the mixer pump 10 measures the temperature of the mixed water downstream of the manifold 16. The sensor 19 is connected to a control device 20, which can be set to adjust the temperature of the mixed water. Adjustment of the water temperature is achieved by varying the speeds of one or other or both of the two pumps 10 and 11 (shown diagrammatically by control lines 21 and 22). If a pump is not used for the supply feed to the mixer pump 10, then some other means of adjusting this feed may be used.
It has been found with the arrangement shown that mixing of the hot and cold water occurs effectively in the manifold 16 of the mixer pump 10. The sensor 18 can therefore be positioned only a relatively short distance downstream of the manifold 16 and yet still give a relatively accurate indication of the temperature of the mixed water. In conventional systems, where mixing of the water is not so effective, temperature sensing at such an early stage is not so accurate, because the flow tends to consist more of discrete streams of hot and cold water.
Mixing in conventional systems can of course be improved by using baffles or other such means to help break up the flow. However, this tends to have the disadvantage of reducing the pressure of the resulting stream, and possibly also its flow rate. By using a special mixing pump and combining the flows in the manner described above, the system shown in Figure 1 can achieve a satisfactory mixing of the two water supplies within a relatively short
distance. It can also provide an effective means of controlling the temperature of the mixed flow without significantly disrupting either its pressure or its flow rate. The system is particularly effective if two pumps are used, as shown.
In an alternative embodiment, the pump assembly could be used to provide a controlled supply of water to an underfioor heating system. The pump assembly would be arranged to mix a supply of hot water from a boiler with cooler water extracted conveniently from the return flow from the heating system. In this case, there may be a need for only one pump in the assembly, namely the mixer pump 10. The supply of hot water from the boiler could be controlled by a modulating valve, ie an infinitely variable valve, such as a motorised valve, a proportional solenoid valve or a thermostatically controlled valve. The modulating valve would be controlled by the control device 20 to regulate the flow of hot water to the mixer pump 10. The control device 20 would at the same time control the speed of the mixer pump 10, in response to the temperature detected downstream by sensor 19 in outlet 18, whereby to regulate the temperature of the mixed water that is supplied to the heating system. It will be appreciated that the systems described may be used to mix other fluids apart from hot and cold water and be used in applications other than for domestic use.