GB2205905A - Lubrication system with stand-by capacity - Google Patents

Abstract

A centralised lubrication system includes a pumping station comprising a single pump head chamber (30) fed from a single reservoir (1) containing lubricant, the chamber being defined within a hollow housing located beneath said reservoir, the chamber (30) being fed with lubricant through a bottom aperture of the reservoir and being normally full of lubricant; means e.g. a weighted piston for expelling lubricant from said reservoir into said chamber; two delivery pumps (31, 32) connected to said housing and having their respective pumping heads (10) located in said single pump head chamber (30), immersed in lubricant, and each adapted to draw lubricant from said chamber and to supply lubricant to a manifold from which lead several lines supplying lubricant to remotely located users; and a respective electric motor for each of the two pumps (31, 32) and control means for bringing one or other of the pumps singly and selectively into operation. <IMAGE>

Description

LUBRICATION SYSTEM WITH STAND-BY CAPACITY This invention relates to centralised lubrication systems of the general kind in which lubrication at a plurality of remotely located users (i.e. items of machinery) is supplied from a central pumping station. The latter comprises a reservoir for lubricant, say of 30 litres, feeding a pump and control gear. The pump itself includes a motor driven pumping head, usualy incorporating an impeller, which head is immersed in grease which it takes in and then expells under pressure to a delivery line leading to one or more users. Control gear is provided to govern operations, and this may be operated so that the pump runs continuously on demand. or at regular intervals, to supply lubricant through a plurality of delivery lines each leading to a respective user at a location remote from the pumping station.The reservoir at the pumping station is often in turn fed with lubricant from a larger bulkstore which may contain some tons of grease.

In such centralised lubrication systems there is often a requirement, for stand-by pumping capacity, at the pumping station, which can be brought into operation in order to enable a primary pump to be serviced or repaired, or in order to allow the control means for the primary pump to be serviced or repaired.

Such stand-by pumping capacity is usually achieved by providing at the pumping station two identical pumps. each with their own lubricant reservoir. Each of these pumps may then be arranged, singly and selectively, to supply a manifold, from which lead the several supply lines to the users; there being means to interrupt one or other of the delivery lines connecting the two pumps to the manifold.

An individual pumping station incorporates electrical controls including high level, low level and intermediate level warning switches for detecting and controlling level of lubricant in the pump reservoir, plus on/off switches and warning controls against failure. Consequently, when there is standby pumping capacity at the centralised pumping station the electrical control system may have to be duplicated and become more complex, particularly where the pumping station is connected up to a bulk grease store, which latter often takes the form of a 3 or 6 tonne grease hopper.Conventionally, when the level of lubricant in one or other of the respective reservoirs of the two pumps falls to a low level, an alarm switch operates and opens a preferably solenoid operated ball valve (alternatively, a manually operated ball valve can be activated) which is effective to create a pressure drop in the bulk grease feed line and this in turn may actuate a separate air-operated barrel pump, to draw grease from the bulk grease hopper and then fill the supply reservoir of any pump at the pumping station requiring replenishment. And it will be appreciated that when standby capacity is provided at the pumping station, the bulk grease pipework and solenoid control valves have to be duplicated, thus increasing the degree of sophistication and, of course, multiplying the risk of problems if something should go wrong.

This invention has for its object to provide stand-by capacity in a centralised lubrication system. in a different and viable manner which gives rise to the possibility of saving on initial cost, of reducing complexity, and of easing the burden of maintainance and servicing.

According to this invention, a centralised lubrication system includes a pumping station which comprises in combination a single pump head chamber fed from a single reservoir filled with lubricant, the chamber being defined within a hollow housing located beneath said reservoir, the chamber being fed from the reservoir through a lower aperture of the reservoir and being normally full of lubricant; means for expelling lubricant from said reservoir into said chamber; and including two delivery pumps connected to said housing and having their respective motor driven pumping heads located in said single pump head chamber and immersed in lubricant, each head being adapted to draw lubricant from said pump head chamber and to supply lubricant to a manifold from which lead several lines supplying lubricant to remotely located users; and including a respective electric motor for each of the two pump-s the motors driving the pumping heads. and control means for bringing one or other of the pumps singly and selectively into operation.

The incorporation of standby pumping capacity into a single two pump unit, with two pumping heads immersed in grease in a single pump head chamber fed by a single reservoir considerably simplifies control, in particular the electrical controls for governing operation of the two motors driving the two pumping heads. However, to effectively incorporate two pumps in one single unit necessitates overcoming certain problems.

Firstly, it is necessary to establish a means whereby both pumping heads in the pump head chamber are effectively primed with lubricant at all times, as failure to do so would create pump head cavitation. Therefore, the problem is to prime both the pumping heads effectively, when only one of the two pumping heads is operating at any one time.

This is achieved by ensuring that the pump head chamber is maintained filled with lubricant at all times when the system is in operation. For example, in the reservoir supplying the chamber, there may be incorporated a weighted piston which, relying upon gravity, pushes the grease into the pump head chamber and towards suction ports of the pump heads. Alternatively, a piston in the reservoir may be spring loaded to achieve the same effect.

The second problem is to prevent grease from exuding out of the hollow housing defining the pump head chamber when a pump is being removed and replaced by a new pump, since, when installing a repaired or new pump into the pump head chamber, a temporary blanking plate having been removed, the grease present is liable to prevent the insertion of the pumping head of the new pump.

This problem is addressed firstly by providing. as temporary blanking plate, a plate which has an inner protruberant part which mimics the shape and volume of the space normally occupied by a pumping head in said pump head chamber.

Secondly. there are provided means for temporarily locking the piston and preventing it falling further to drive grease from the pump reservoir into the pump head chamber. For this purpose. the piston will have a rod which extends through a gland seal in a top cover, upwardly out of the pump reservoir. and a clamp sleeve is provided on the external portion of this rod, axially movable there over, and clampable to the rod, temporarily to prevent movement of the rod into the reservoir.

Alternatively or in addition, for solving the second problem identified above, a gate valve may be provided between the pump head chamber and the pump reservoir which is immediately above it, and this valve may be closed when one or other of the pump heads is to be removed from the pump head chamber. This valve may be a butterfly valve and may be manually operable.

One embodiment of the invention is shown by way of example in the accompanying drawings in which Figures 1 to 3 are respectively front plan and side views of a pump installation with dual pumps fitted, the heads of the two pumps taking lubricant from a single common pump head chamber which is fed from an overlying pump reservoir.

Figure 4 is a cross sectional view of the pump reservoir and showing a weighted piston for driving lubricant through a bottom aperture into the common pump head chamber for supplying pumping heads of the two pumps.

Figure 5 is a side view of a blanking plate provided according to one aspect of the invention.

According to the embodiment of this invention as illustrated in the drawings, a centralised lubrication system includes a pumping station which includes in combination a single pump head chamber generally designated 30 fed from a single reservoir 1 filled with lubricant such as grease; the chamber 30 being defined within the interior of a hollow housing 33 located beneath said reservoir 1.

the chamber 30 being fed from the reservoir through an bottom aperture 40 of the reservoir and being normally maintained full of lubricant.

As shown in Figure 4, the reservoir has an upper space defined by a generally cylindrical housing part 5 and a lower space defined by a conically tapered part 6 leading to the bottom aperture 40. A piston 14 is movable within the cylindrical housing part 5. Means (not shown) will be provided for maintaining said reservoir 1 full of lubricant to a predetermined extent, lubricant being supplied by way of an inlet 11. The piston 14 is employed to expel lubricant from said reservoir 1 through the aperture 40 and into the chamber 30.

Two delivery pumps generally designated 31 and 32, each comprising an electric motor 9 and a pumping head 10 driven thereby, are connected to opposite sides of the housing 33 with their respective pumping heads 10 located in said single pump head chamber 30. Each pumping head 10 is adapted, when in operation, to draw lubricant from said chamber 30 and to supply lubricant through a delivery port 12 to a manifold (not shown) from which will lead several lines supplying lubricant to remotely located users.

Electric control means will be provided whereby one or other of the pump motors may be brought singly and selectively into operation.

The provision of standby pumping capacity in a single unit by the incorporation of two pumping heads 10 into a single pump head chamber 30 fed by a single reservoir 1, considerably simplifiers control, in particular electrical control. However, to incorporate two pumps effectively in one single unit necessitates overcoming certain problems.

Firstly, it is necessary to establish a means whereby both pumping heads 10 in the pump head chamber 30 are effectively primed with lubricant at all times, as failure to do so would create pump head cavitation. Therefore, the problem is to prime both the pumping heads effectively, when only one of the two pumps is operating at any one time.

This is achieved by ensuring that the pump head chamber 30 is maintained filled with lubricant at all times when the system is in operation. For example, the piston 14 in the reservoir 1 supplying the chamber 30, may be constituted as a weighted piston which, relying upon gravity, pushes the grease into the pump head chamber 30 and thence to suction ports of the pumping heads 10.

Alternatively or additionally, the piston 14 in the reservoir 1 may be spring loaded to achieve the same effect.

The second problem is to prevent grease from exuding out of the pump head chamber housing 33 when a failed pump is being removed and replaced by a new pump, since, when installing a repaired or new pump into the pump head chamber, a temporary blanking plate having been removed, the grease present is under pressure from the piston in the pump reservoir and is thus liable to move into the space just vacated by the pump head being replaced, this being effective to inhibit the insertion of the new pump head.

This problem is addressed firstly hy providing, for functioning as a temporary blanking plate, and as shown in Figure 5, a plate 35 which has an inner protruberant part 34 which mimics the shape and volume of the space, normally occupied by a pumping head in said pump head chamber. Thus whenever a pump has to be removed it is temporarily replaced by a plate such as the plate 35.

Secondly, there are provided means for temporarily holding the piston 14 and preventing it falling further to drive grease from the pump reservoir into the pump head chamber. For this purpose, the piston has a rod 3 which extends through a gland seal in a top cover 2, upwardly out of the pump reservoir, and a clamp sleeve 8 is provided on the external portion of this rod, axially movable thereover, and clampable to the rod by tightening a grub screw 7, temporarily to prevent movement of the rod 3 into the reservoir 1, thus preventing the piston 14 from expelling grease from the reservoir.

Alternatively or in addition, for solving the second problem identified above, a gate valve may be provided to cut off communication between the pump reservoir 1 and the pump head chamber 30 which is immediately beneath it, and this valve may be closed when one or other of the pump heads is to be removed from the pump head chamber. This valve may be a butterfly valve and may be manually operable. Such a valve will be located in the lower space defined by the tapered wall part 5 of the reservoir 1 at or adjacent the bottom aperture 40 thereof.

Claims (6)

1. A centralised lubrication system which includes a pumping station comprising in combination a single pump head chamber (30) fed from a single reservoir (1) containing lubricant, the chamber being defined within a hollow housing (33) located beneath said reservoir, the chamber (30) being fed with lubricant through a bottom aperture (40) of the reservoir and being normally full of lubricant; means for expelling lubricant from said reservoir into said chamber; and including two delivery pumps (31, 32) connected to said housing (33) and having their respective pumping heads (10) located in said single pump head chamber (30).

immersed in lubricant, and each adapted to draw lubricant from said chamber and to supply lubricant to a manifold from which lead several lines supplying lubricant to remotely located users; and including a respective electric motor for each of the two pumps (31, 32) and control means for bringing one or other of the pumps singly and selectively into operation.

2. A system according to claim 1 wherein said piston (14) is a circular piston moving over a cylindrical wall part (5) of the reservoir, and is weighted sufficiently to expel lubricant through the aperture (40) into chamber (30) by force of gravity.

3. A system according to either of claims 1 or 2 wherein a spring acts on said piston (14).

4. A system according to any preceding claim, and including a rod (3) on the piston (14) which rod extends through a top cover (2) of the reservoir (1). and including a manually operable clamp (8) engagable with the rod (3), said clamp being so engaged to rest on the top cover (2) and maintain the piston (14) at a selected height in the reservoir (1).

5. A system according to any preceding claim, and including a gate valve operative to obturate the aperture (40).

6. A system according to any preceding claim and wherein each pump (31,32) is detachably secured to the housing (33) defining the chamber (30); and wherein on a said pump being detached, there is provided a masking plate (35) having a protuberant portion (34) shaped and configured to mimic the head (10) of the pump (31,32) so removed, said plate (35) being adapted to be clamped in place of a pump so removed.