GB2544756A

GB2544756A - Pump assembly incorporating a sump

Info

Publication number: GB2544756A
Application number: GB1520775.6A
Authority: GB
Inventors: Lilly Stephen
Original assignee: Ebac Ind Products Ltd
Current assignee: Ebac Ind Products Ltd
Priority date: 2015-11-24
Filing date: 2015-11-24
Publication date: 2017-05-31
Also published as: GB2544842B; GB201612263D0; GB2544842A; GB201520775D0

Abstract

A condensate pump assembly comprising a sump 1 with an inlet port, an outlet port 9, and a bottom wall 2. A float 22 is arranged to operate a control sensor to turn off the motor 6 when liquid within the sump falls to a predetermined lower level. The bottom wall includes an impeller well 20 which snugly receives an impeller 15 of the pump and a float well 21 to receive the float. The impeller for pumping liquid from the sump through the outlet port 9 may be contained within an impeller housing 10 which may be secured to a removable cover 5 along with a pump motor 6. The impeller housing 10 may have liquid inlets 19 at the same level as an adjacent region of the bottom wall. The float may be carried by an L-shaped float arm with a first cam arranged to operate the control sensor and a second cam arranged to operate a high-level sensor when the liquid rises to a predetermined upper level. The residual water level is reduced and the pump is more compact and reliable.

Description

Ebac Industrial Products Limited

PUMP ASSEMBLY INCORPORATING A SUMP

TECHNICAL FIELD OF THE INVENTION

This invention relates to pump assemblies of the kind which incorporate a sump for collecting liquid.

BACKGROUND

Vapour compression circuits used in dehumidifiers, refrigerators, air conditioning units, heat pumps and the like, have a compressor, a condenser and an evaporator. They may also be provided with a condensate pump to remove water which condenses on the evaporator. Known condensate pumps take the form of a pump assembly which includes a tank, or sump, for collecting the condensate and a centrifugal pump driven by a motor. The liquid level in the sump controls the motor to feed the collected condensate to a suitable waste outlet or drain. Such pump assemblies generally include two float-operated switches. One turns off the motor when the fluid level in the sump falls to a predetermined low level, and a second switch with its own float acts as a safety cutout to turn off the compressor in the event that the liquid level reaches a predetermined upper limit.

In such pumps a certain amount of water always remains in the sump when the appliance is switched off. This can lead to corrosion, produce unpleasant smells, and may even pose health risks. In portable appliances significant volumes of residual water are particularly undesirable since the pump tanks are not sealed, and this can result in spillages when the unit is moved.

SUMMARY OF THE INVENTION

The present invention provides a pump assembly incorporating a sump with inlet and outlet ports and a bottom wall, an impeller for pumping liquid from an interior of the sump through the outlet port, a motor for driving the impeller, and a float arranged to operate a control sensor when liquid within the sump falls to a predetermined lower level, in which the bottom wall of the sump includes an impeller well which contains the impeller and a float well to receive the float when the liquid falls to said lower level.

The invention also provides a pump assembly in which an impeller is contained within an impeller housing which is snugly received in an impeller well.

The invention also provides a pump assembly incorporating a sump with a bottom wall and an impeller well, in which an impeller housing has liquid inlets at the same level as a region of said bottom wall which is adjacent to the impeller well.

The invention also provides a pump assembly in which an impeller housing is fixed with a removable cover.

The invention also provides a pump assembly in which a float is carried by a float arm.

The invention also provides a pump assembly in which a float is carried by a float arm which is substantially L-shaped with a pair of orthogonal limbs.

The invention also provides a pump assembly in which a float moves angularly.

The invention also provides a pump assembly in which a float is carried by a float arm which is arranged to operate a control sensor.

The invention also provides a pump assembly in which a float is arranged to operate a high-level sensor when liquid rises to a predetermined upper level.

BRIEF DESCRIPTION OF THE DRAWINGS

The following description and the accompanying drawings referred to therein are included by way of non-limiting example in order to illustrate how the invention may be put into practice. In the drawings:

Figure 1 is a plan view of a condensate pump assembly;

Figure 2 is section A-A through the pump assembly as indicated in Fig. 1, the pump assembly being shown in an off condition;

Figure 3 is a side view of the pump assembly in an empty condition, partly cut away, including an inset detail;

Figure 4 is a similar side view but showing the pump assembly in a partially full condition; and

Figure 5 is another similar side view showing the pump assembly in a full condition.

DETAILED DESCRIPTION OF THE DRAWINGS

Referring firstly to Fig.s 1 and 2, the condensate pump assembly includes a generally rectangular tank or sump 1 with a bottom wall 2 surrounded by an upstanding side wall 3. The sump 1 has an top opening 4 provided with a cover 5, both of which are preferably moulded of thermoplastic material. As is often the case, the cover 5 does not form a water-tight seal with the sump 1, which may be desirable for various reasons, e.g. to allow the sump to dry out when not in use. A pump motor 6 is mounted on the cover 5 together with a switch block 7. The cover also incorporates an inlet opening 8, through which condensate water is received from the evaporator of an associated dehumidifier or similar equipment, and an outlet connector 9 to which a discharge conduit can be connected to feed the condensate to a suitable waste outlet or drain. The conduit may discharge at a higher or lower level than the equipment but the condensate pump provides sufficient pressure to ensure that the condensate water is always removed.

The underside of the moulded cover 5 is provided with an impeller housing 10 which is divided by a horizontal dividing wall 11 into an upper inflow chamber 12 and a lower impeller chamber 13 of substantially circular shape. A discharge passage 14 leads from one side of the impeller chamber 13 and rises vertically along one side of the impeller housing 10 to join the aforementioned outlet connector 9.

The impeller chamber 13 contains a disc-shaped impeller 15 of known construction, including a number of impelling vanes 16 extending outwardly from a central hub 17 which extends through the dividing wall 11. A drive shaft 18 leads from the pump motor 6 and through the inflow chamber 12 to drivably connect with the hub 17. At the bottom of the inflow chamber 12 the wall of the impeller housing 10 contains an array of circumferentially spaced axially extending condensate inlet slots 19 which allow condensate to flow from the sump 1 into the inflow chamber 12 before passing onward into the impeller chamber 13. The water level within the sump 1 must at least partially cover the inlet slots 19 for the impeller 15 to centrifugally drive water from the impeller chamber 13 out through the discharge passage 14 to be delivered through the outlet connector 9.

The bottom wall 2 of the moulded sump 1 includes an impeller well 20 which is shaped to snugly receive the bottom end of the impeller housing 10 such that the condensate inlet slots 19 are substantially level with the adjacent area of the bottom wall 2. Furthermore, the bottom wall of the sump contains a float well 21, spaced from the impeller well 20, to receive a single float 22 which rises and falls with the water level within the sump 1. At its lowest position, as shown, approximately half of the float 22 is snugly received within the float well 21 with a substantially planar bottom face of the float seated against the flat bottom of the float well.

Referring now to the cut-away side view of Fig. 3, the float 22 is carried by a generally L-shaped arm 23 at one end of generally horizontal limb 23a. The upper end of generally vertical limb 23b passes through the cover 5, above which the arm is suspended from a horizontal pivot 24 (see inset enlarged detail) for angular movement. The upper end of limb 23b has a nose 25, extending towards the same side as limb 23a, which carries a pair of switch-operating cams 26 which are spaced axially of the pivot 24 on opposite sides of the nose 25. The cams 26 operate respective sensors included in the switch block 7, namely a control sensor microswitch 27 and a high-level sensor microswitch 28 (Fig. 1). The cams 26 operate the microswitches 27 and 28 via respective spring levers 29.

When the sump 1 is substantially empty the float is in its lowermost position shown in Fig.s 2 and 3 and both microswitches 27 and 28 are open. As the water level rises due to condensate from the evaporator flowing under gravity into the sump 1 the float 22 is carried upwards by the increasing water level causing the arm 23 to rotate in a clockwise direction (as viewed in the drawings) to the position shown in Fig. 4. In so doing the float moves angularly so that its bottom face is now at an angle to the bottom wall of the float well (approximately 10 degrees in the drawing). This causes the first of the two cams 26 to operate the control sensor microswitch 27 causing the motor 6 to drive the impeller 15 to pump water from the sump 1.

Should the rate at which condensate is delivered to the sump 1 exceed the pumping capacity of the centrifugal impeller the float 22 will rise still further causing the arm 23 to move to the position shown in Fig. 5 The angle of the float continues to increase until its bottom face reaches an angle of about 23 degrees to the bottom wall of the float well. This further angular movement results in the second of the two cams 26 operating the high-level sensor microswitch 28 so that both switches are now 'on'. Operation of the high-level sensor may cause various actions such as activating an alarm , shutting down the compressor so that the evaporator temperature rises, etc. Since the control sensor microswitch 27 is still closed the pump will continue to run and remove water from the sump 1.

When the water level in the sump 1 eventually falls back towards the condition shown in Fig. 4 the high-level sensor 28 will cease to operate and pumping will continue. Should the water level drop sufficiently to return to the condition shown in Fig. 3 the control sensor microswitch 27 will open and the motor will cease to run. Under such conditions the amount of residual water remaining in the sump, indicated by the solid black area in Fig. 2, is considerably less than conventional condensate pumps with two separate float-operated switches.

The form of condensate pump described has many advantages including the fact that the low residual water volume minimises spillages and allows the sump to dry out quickly when not in use reducing the risk of unpleasant smells and bacterial contamination. The simplified construction of the pump also reduces the size of the condensate pump for a given capacity, increases reliability, and reduces manufacturing cost.

Whilst the above description places emphasis on the areas which are believed to be new and addresses specific problems which have been identified, it is intended that the features disclosed herein may be used in any combination which is capable of providing a new and useful advance in the art.

Claims

1. A pump assembly incorporating a sump with inlet and outlet ports and a bottom wall, an impeller for pumping liquid from an interior of the sump through the outlet port, a motor for driving the impeller, and a float arranged to operate a control sensor when liquid within the sump falls to a predetermined lower level, in which the bottom wall of the sump includes an impeller well which contains the impeller and a float well to receive the float when the liquid falls to said lower level.

2. A pump assembly according to Claim 1 in which the impeller is contained within an impeller housing which is snugly received in the impeller well.

3. A pump assembly according to Claim 2 in which the impeller housing has liquid inlets at the same level as a region of said bottom wall which is adjacent to the impeller well.

4. A pump assembly according to Claim 2 or 3 in which the impeller housing is fixed with a removable cover for the sump.

5. A pump assembly according to any preceding claim in which the float is arranged to operate a high-level sensor when liquid within the sump rises to a predetermined upper level.

6. A pump assembly according to any preceding claim in which the float is carried by a float arm.

7. A pump assembly according to Claim 6 in which the float arm is substantially L-shaped with a pair of orthogonal limbs.

8. A pump assembly according to Claim 6 or 7 in which the float moves angularly.

9. A pump assembly according to Claim 6, 7 or 8 in which a first cam moves with the float arm and is arranged to operate the control sensor.

10. A pump assembly according to Claim 9 in which a second cam moves with the float arm and is arranged to operate a high-level sensor when the liquid rises to a predetermined upper level.

11. A pump assembly substantially as described with reference to the drawings.