GB2122693A - Improvements relating to pumps - Google Patents

Abstract

A pump, primarily for showers, uses the high pressure cold water supply to drive a double acting piston (4) in a cylinder to which the hot water supply (41) is also directed, thereby boosting the hot water pressure. Mixing of hot and cold is achieved by bleeding off cold water from the supply by a valve into the outlet, reduction in delivered hot water as a result of less drive to the pump being compensated by this diverted cold water. The cold water is admitted to the cylinder via valves (30) operated through a lost motion connection (9, 12, 14, 18, 17, 22, 25, 27, 32) to the piston (4) so that each valve event occurs at the end of a stroke. The hot water is admitted to and discharged from other parts of the cylinder through non-return valves. <IMAGE>

Description

SPECIFICATION Improvements relating to pumps This invention relates to pumps.

A domestic shower may be installed independently with a single cold water supply and its own thermostatically controlled heater. These tend to be very expensive, and are often disruptive to fit, since not only is there the basic plumbing, but also electric cable or gas piping to provide.

Alternatively, the shower may be supplied from the ordinary hot and cold system, and either have its own separate cubicle or be incorporated with the bath tap assembly. There has to be some mixing to attain an acceptable temperature, but this is often difficult to achieve. Also, particularly when the shower head is hand held, alterations to its height disrupt the pressure balance between hot and cold and therefore give rise to substantially different temperatures. The cold water supply is usually from the mains and can be regarded as being of substantially constant pressure, and very much higher than that of the hot water whose head is that of a tank above the cylinder, often in the airing cupboard. If that is in the bathroom, then raising and lowering the shower head can have a proportionately very significant effect on the hot water pressure.

It is the aim of this invention to provide a device which can largely remove this potential fluctuation, and which can easily and rapidly be fitted to hot and cold water taps.

According to the present invention there is provided a hydraulic pump energiseable by fluid from a first, high pressure supply to pump fluid from a second, low pressure supply, wherein there are adjustabie means for mixing said supplies before delivery from a common outlet.

Preferably, the pump is of double acting reciprocating type, with a double headed piston in a cylinder having divider means which co-operate with the piston between its heads to define annular working chambers for one fluid, the working chambers for the other fluid being the cylindrical spaces between the piston heads and the adjacent cylinder ends.

For a shower pump, said one fluid will be the high pressure cold supply from the mains, the other fluid being the hot water. This will be delivered at greater pressure than that normally available and it will also be at substantially constant pressure as determined by the cold water pressure.

Valve means will be provided for admitting and releasing the high pressure fluid to and from the annular chambers in alternation, the operation of the valve means being via a lost motion connection to the piston. This connection may include a member within the piston which is entrained thereby towards the end of each stroke, and which has a sealed link to the valve means through one end of the piston and cylinder. It may also include spring means arranged to be stressed to a given level before transmitting motion causing a valve event, for example a catch may be released when the stress attains said level.

Preferably non-return valves will be arranged to govern the flow of the low pressure fluid into and out of the cylinder end chambers.

The adjustable mixing means conveniently comprises a valve arranged to divert a selected proportion of fluid from said first supply upstream of entry to the pump into the outlet. With this control, as the cold water is bled off from its route to driving the pump, so the latter slows down and reduces the hot water supply. But the amount of cold water which is mixed with the hot water and delivered directly to the outlet is increased. Thus a substantially constant volume is maintained, but with a responsive temperature control.

Turning either the hot or could supply off will hydraulically lock the pump, but a cold only output can be obtained by turning on the cold supply and the diverting valve so that the cold water by-passes the pump altogether.

For a better understanding of the present invention, an embodiment will now be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is a longitudinal section of a shower pump, Figure 2 is a section on the line 11II of Figure 1, Figure 3 is a section on the line lillil of Figure 1, Figure 4 is a section on the line IVIV of Figure 1, Figure 5 is a section on the line VV of Figure 1.

Figure 6 is a plan view of the pump, with a valve chamber cover removed, and Figure 7 shows side views of valve members.

The shower pump has a cylinder 1 constructed in two halves 1 a and 1 b co-axially press or otherwise permanently fitted into opposite sides of a central ring 1 c. The other ends of the cylinder parts 1 a and 1 b are similarly fitted into end plates 2 and 3, and inside the cylinder there is a double acting piston 4. The piston has enlarged diameter ends provided by rings 6 captive in annular grooves in end discs 7, with an intermediate cylindrical body portion 5 whose outer circumference is a close sliding fit with a separator sealing ring 8. This has an outer profile shaped to co-operate with a central inner rib formation of the ring 1 c, and it will generally be fused or otherwise permanently secured in position.Thus there are four working chambers, namely the two cylindrical ones at the ends of the cylinder 1 and the two annular ones either side of the ring 8 and defined by the rings 6.

The hollow piston 4 encloses a cylindrical body 9 which is a loose sliding fit and moves with the piston in either direction after a lost motion interval while the piston performs the first part oi its stroke. The end plate 3 has a tube 10 fixed normally to it to project co-axially through the adjacent end disc 7 via seals 11 on opposite faces and almost to the centre of the cylinder 1. The body 9 is constructed freely to accommodate this end of the tube, which acts as a guide for a flexible line 12, of nylon for example. One end of this line is attached to the left hand end (as seen) of the body 9 and the other end to the right hand side, whence it is rove around a pulley 13 before entering the tube 10.The bight of the line is led smoothly out of the other end of the tube, beyond the plate 3, to turn at right angles and traverse a pulley 14. It will be seen that as the body 9 moves back and forth, so the pulley 14 will be oscillated on its bearing pin 15, which is parailel to the cylinder axis.

The pulley 14 and the adjacent end of the tube 10 are concealed within an end cover 1 6 which fits to the plate 3, and the pin 15 is mounted between this cover and the plate. Beyond the pin 15 from the cylinder 1 a part rotary shaft 17 enters the cover space and its end carries a rocker 18 which freely embraces the pin 15, having an arcuate slot 1 9 as seen in Figure 4, and extends towards the lower end of the pulley as viewed in Figure 1. There it is acted upon in opposite directions transverse to its pivot axis by stiff springs 20 which react against wings 21 of the pulley. Thus as the pulley oscillates, so the rocker is pivoted to and fro, rotating the shaft 17, the springs 20 introducing some delay in the system, as explained below.

Outside the plate 3, the shaft 1 7 is fitted with a block 22 having a spring loaded plunger 23 which can engage in either one of two detents 24 in the plate. These are arranged so that there is a positively held dwell at the end of each stroke, before it is broken by the action reversing. The opposite, lateral ends of the block 22 have studs 25 which engage the ends of valve actuating links 26 and 27 and the other end of the shaft is mounted in a valve block 28 on the sides of which these links extend.

The valve block 28 is mounted on the ring 1 c (it could be made integral with it) and houses two valve members 29 and 30 which are mounted on respective co-axial shafts 31 and 32 actuated by the links 26 and 27. Each valve member is roughly triangular, with its shaft transverse to it and near the apex, while the base is divided into two parts at an obtuse angle such that, at the extremes of the valve rocking motion, one or other of those parts is flat against a portion surface. This base may have seals 33 bonded to it, as shown in one detail of Figure 7 or the port surface may have a seal 34, as shown in the other detail.

The four ports which these valves open and close lead via ducts 35 through the ring 1 C to the annular chamber surrounding the piston 4, one to each side from each valve. The valve motion is such that, while one chamber is open by one port to the first valve, a port associated with the other chamber is opened by the other valve, and vice versa. One valve chamber 36 will receive cold water under pressure from a pipe 37 thus causing the annular chamber to which it is connected to expand, while the other valve chamber 38 connects to a pipe 39 which takes the water from the reducing size chamber to drain. Thus the cold water from pipe 37 will drive the piston 4 back and forth with the valves 29 and 30 being suitably operated at the end of each stroke. In brief, the body 9 is caught up by the piston and rotates the pulley 14 via the line 12.This compresses and tensions the springs 20 which act on the rocker 1 8 until the plunger 23 snaps clear of one of the detents 24, whereupon the shaft 1 7 rapidly turns and actuates the links 26 and 27.

The end plates 2 and 3 incorporate ports and valves for hot water, as best seen in Figures 2 and 3. A hot water supply pipe 41 leads to the plate 2, and extends through it, parallel to the cylinder 1, to the plate 3. Within the plate 2 it communicates by a port 42 with a valve chamber 42 and thence via a further port 44 to the adjacent end of the cylinder 1. The valve member is a U-shaped membrane 45, one of whose flanges is longer than the other and normally covers the entry of the port 42 into the chamber 43, the rest of the valve member 45 seating snugly to the profile of one side of the chamber. At the other end, in plate 3, the pipe communicates via port 46, valve chamber 47, and a further port 48 with the other end of the cylinder 1 when a similar valve member 49 opens the port 46.

Another hot water pipe 50, for the outflow from the pump to a shower head (not shown) in this example, extends between the plates 2 and 3 and beyond, and has simiiar communication with the cylinder 1. Within the plate 3, there is a port 51, a valve chamber 52, and a port 53, with a valve member 54 reversed as compared with the valve member 49, so that its longer flange overlies the port 53.

Within the plate 2, there is a port 55, a valve chamber 56 and a port 57, with a valve member 58 arranged similarly to the member 54 to cooperate with the port 57. In addition, there is a duct 59 leading from a branch 60 taken from the cold water supply pipe 37 as it passes through the plate 2. It can be closed or opened to a selected extent by a needle 61 operated with screw action by a knob 62. Thus, cold water can be bled into the hot water delivery pipe 50.

The pump action of the piston 4 has already been described, and as it moves back and forth so hot water is drawn in through pipe 41 to the expanding chamber at one end of the cylinder 1 while hot water is expelled under greater pressure than its norm from the reducing volume chamber at the other end, the membrane valves within the plate 2 and 3 operating automatically. As the cold water supply is increased, the pump will operate faster. If the cold water supply is turned off, and the hot water is fully on, the pump will not operate and there will be no supply from the pipe 51.

If the supply is too hot for comfort, the knob 62 can be turned to bleed some cold water into the pipe 50. This will cooi the delivered hot water, and at the same time reduce the cold water available for driving the pump. Therefore, the flow will remain substantially constant, the reduction in hot water, as a result of less drive to the pump, being compensated by the make-up cold water through the duct 59.

If a cold shower is required, simply turning the hot water supply off will hydraulically lock the pump, while opening the needle valve 61 will admit cold water directly to the delivery pipe 50.

Although this is a reciprocating pump which would normally be expected to produce a pulsed supply, it has been found that, when used in conjunction with plastics or rubber connection hoses to the pipes 37, 39, 41 and 50, these pipes themselves will act as dampers to smooth out the flow. However, it would be possible to provide a pressure accumulator.

It will be understood that there will be an overall casing to enclose the cylinder, the valve block 27 and the links 26 and 27 so that the device will appear simply as a box with a single control knob.

Claims (9)

1. A hydraulic pump energisable by fluid from a first, high pressure supply to pump fluid from a second, low pressure supply, wherein there are adjustable means for mixing said supplies before delivery from a common outlet.

2. A pump as claimed in claim 1, wherein it is of double acting reciprocating type, with a doubleheaded piston in a cylinder having divider means which co-operates with the piston between its heads to define annular working chambers for one fluid, the working chambers for the other fluid being the cylindrical spaces between the piston heads and the adjacent cylinder ends.

3. A pump as claimed in claim 2, wherein valve means are provided for admitting and releasing the high pressure fluid to and from the annular chambers in alternation, the operation of the valve means being via a lost motion connection to the piston.

4. A pump as claimed in claim 3, wherein the lost motion connection includes a member within the piston which is entrained thereby towards the end of each stroke, and which has a sealed link to the valve means through one end of the piston and cylinder.

5. A pump as claimed in claim 3 or 4, wherein the lost motion connection includes spring means arranged to be stressed to a given level before transmitting motion causing a valve event.

6. A pump as claimed in claim 5, wherein the lost motion connection includes a catch which is released when the stress attains said level.

7. A pump as claimed in any one of claims 2 to 6, wherein non-return valves are arranged to govern the flow of said other fluid into and out of the cylinder end chambers.

8. A pump as claimed in any preceding claim, wherein the adjustable mixing means comprises a valve arranged to divert a selected proportion of fluid from said first supply upstream of entry to the pump into the outlet.

9. A hydraulic pump substantially as hereinbefore described with reference to the accompanying drawings.