GB2252364A

GB2252364A - Fluid pressure intensifier

Info

Publication number: GB2252364A
Application number: GB9201438A
Authority: GB
Inventors: Roger Harold Creasey; Dennis Alfred Perry
Original assignee: SENIOR MINING EQUIPMENT LIMITE
Current assignee: SENIOR MINING EQUIPMENT LIMITE
Priority date: 1991-01-31
Filing date: 1992-01-23
Publication date: 1992-08-05
Anticipated expiration: 2012-01-23
Also published as: GB2252364B; GB9102073D0; GB9201438D0

Abstract

A fluid pressure intensifier comprises a reciprocable ram (H) in a high pressure generating chamber with a common low and high pressure port leading to check valves (D, I), the first (D) permitting low pressure fluid inflow to chamber (F) and the second (I) permitting high pressure fluid outflow from chamber (F). A piston (G) is connected to the ram (H) and has a larger diameter. A cylinder in which the piston moves defines a low pressure chamber (E), and low pressure fluid fed thereto acts on piston (G) to displace the piston (G) and ram (H) in a ram delivery stroke. A fluid outlet route from the low pressure chamber (E) to exhaust is also provided. A shuttle valve (A, B) serves, to open the inlet route and simultaneously close the outlet route, and in a second position to close the inlet route and simultaneously open the outlet route, and a lost motion mechanism (M, N, J, K, L) between piston (G) and the shuttle valve (A, B) ensures that, towards each end of the ram stroke, the shuttle valve means is automatically displaced to the other of its two positions. <IMAGE>

Description

FLUID PRESSURF: INTENSIFIER This invention relates to a fluid pressure intensifier, particularly though not exclusively, for intensifying the pressure of a fluid such as pure water from a lower pressure to a higher pressure.

Fluid pressure intensifiers, and hydraulic pumps, are known of the reciprocating ram type, with the chamber swept by the ram having a common supply and delivery port and two associated check valves, the first in a low pressure delivery line which unseats during the ram retraction stroke to permit supply of a charge of lower pressure fluid to the chamber and which becomes seated by the higher pressure generated at the start of the ram delivery stroke, and the other in a high pressure delivery line which 15 unseated only by the higher pressure. Piston reciprocation is normally by a cam or swash plate powered by a prime mover, usually an electric motor.

The object of the present invention is to provide a reciprocable ram intensifier in which no prime mover is required.

According to the present invention there is provided a fluid pressure intensifier comprising: (i) a reciprocable ram; (ii) a high pressure generating chamber adapted to be swept by the ram; (iii) a common low pressure supply and high pressure delivery port connected to the chamber; (iv) first and second pressure responsive check valves associated with the common port, the first unseating to permit low pressure fluid inflow to the high pressure chamber and the second unseating to permit high pressure fluid outflow from the high pressure chamber; (v) a piston of larger diameter than the ram and connected to the ram; (vi) a cylinder in which the piston is reciprocable to define a low pressure chamber;; (vii) a low pressure fluid inlet route to the low pressure chamber to permit low pressure fluid to act on the larger diameter piston to displace the piston and hence the connected ram in a ram delivery stroke; (viii) an fluid outlet route from the low pressure chamber to exhaust; (ix) shuttle valve means to, in a first position, open the inlet route and simultaneously close the outlet route, and in a second position to close the inlet route and simultaneously open the outlet route, and (x) a lost motion mechanism between the larger diameter piston and the shuttle valve means, whereby towards each end of the ram stroke, the shuttle valve means is automatically displaced to the other of its two positions.

It will be appreciated that, at the end of the ram delivery stroke, the pressure in the low pressure chamber falls as that chamber is connected to exhaust and at least initially the high pressure chamber still contains fluid at the intensified pressure resulting in the ram commencing its return stroke and drawing into the high pressure chamber a fresh charge of low pressure fluid, the ram, which is now subject to low pressure fluid, continuing to drive the larger area piston which is still connected to exhaust until, at the end of the charging or "induction" stroke, the lost motion mechanism is again activated to displace, and hence change the state of the shuttle valve, to re-commence the cycle, by closing the exhaust route from the low pressure chamber and opening the low pressure supply route to the low pressure chamber.

Conveniently, the ram and enlarged piston are formed integrally. Preferably, the shuttle valve is reciprocable along a line co-axial with the axes of the ram and enlarged piston. In the latter case, the lost motion mechanism can conveniently consist of a co-axial rod connected to valve members of the shuttle valve means and terminating in an enlarged head so located within a bore of the integral ram and enlarged piston, bore has abutment means at its opposite ends, that at the end of the ram delivery stroke the rod, and hence the shuttle valve members are pulled in the ram delivery direction to achieve change-over, and at the end of the ram retraction stroke, are pushed in the ram retraction direction to achieve change-over.

The check valves associated with the high pressure chamber are preferably spring-loaded ball valves, while the valve members. of the shuttle valve means are preferably poppet valves. It is also preferred to be provided at least one and preferably two core compression springs which recoil upon ram movement halting, to urge the shuttle valves on to, or off, their seats.

The ratio of pressure intensification, i.e. the enlarged piston area compared with the ram area, may be as required by the user but 6:1 is typical.

The invention will now be described in greater detail by way of example, with reference to the accompanying diagrammatic drawings, in which: Figures 1 to 4 show diagramatically four stages in the intensification cycle; Figure 5 shows further details of the device of Figures 1 to 4, being an axial section view; Figure 6 corresponds to Figure 5 but shows a further embodiment; and Figure 7 corresponds to Figure 5 but shows yet a further embodiment.

In Figure 1, low pressure water enters the low pressure chamber E through valve member A of the shuttle valve means, while valve member B simultaneously closes the exhaust route. At the same time, low pressure water unseats check valve D and enters high pressure chamber F.

As shown in Figure 2, low pressure water acting on the larger area piston G begins to displace the piston and hence the ram H to the right, thereby commencing the ram delivery stroke and generating an intensified pressure (coloured black) in the high pressure chamber F which seats check valve D and unseats check valve I.

A bore J in the enlarged piston G and ram H, has opposed abutment ends K nd L. Within the bore J is one end of a rod M of a lost motion mechanism, the rod terminating in an enlarged head N and at its other end being connected to valve member A, which in turn is connected to valve member B.

In Figures 1 and 2, the lost motion mechanism is not activated, as it is not required to change the state of the shuttle valve means until the position illustrated in Figure 3 is reached, when the ram H is just reaching the end of its delivery stroke, in which position abutment end K strikes the head N pulling the lost motion mechanism to the right until valve member A closes on its seat and valve member B opens, to connect the low pressure chamber E to exhaust. With the resulting fall in pressure in the low pressure chamber E, the ram H and enlarged piston G begin their return movement, check valve I closes, check valve D eventually opens when pressure in the high pressure chamber F approximates to the lower supply pressure. Continued movement to the left is eventually completed when abutment L strikes the head N resulting in a change of state of the shuttle valve and a repeat of the cycle.

Whilst Figures 1 to 5 have been concerned with a single-acting device, the same principle can be applied to a double-acting device, i.e. one which both delivers and exhausts on each stroke, and an example is illustrated in Figure 6. Also Figures 5 and 6 have a first compression spring P while Figure 7 has first and second compression springs P and Q. At the end of each stroke, these springs are compressed due to movement and inertia of the ram H, such that when the latter comes to a stop the compressed spring P or Q recoils and urges the shuttle valves A, B on to, or off, their respective seats.

Claims

1. A fluid pressure intensifier comprising: (i) a reciprocable ram; (ii) a high pressure generating chamber adapted to be swept by the ram; (iii) a common low pressure supply and high pressure delivery port connected to the chamber; (iv) first and second pressure responsive check valves associated with the common port, the first unseating to permit low pressure fluid inflow to the high pressure chamber and the second unseating to permit high pressure fluid outflow from the high pressure chamber; (v) a piston of larger diameter than the ram and connected to the ram; (vi) a cylinder in which the piston is reciprocable to define a low pressure chamber; (vii) a low pressure fluid inlet route to the low pressure chamber to permit low pressure fluid to act on the larger diameter piston to displace the piston and hence the connected ram in a ram delivery stroke;; (viii) an fluid outlet route from the low pressure chamber to exhaust; (ix) shuttle valve means to, in a first position, open the inlet route and simultaneously close the outlet route, and in a second position to close the inlet route and simultaneously open the outlet route, and (x) a lost motion mechanism between the larger diameter piston and the shuttle valve means, whereby towards each end of the ram stroke, the shuttle valve means is automatically displaced to the other of its two positions.

2. An intensifier as claimed in Claim 1, wherein the ram and enlarged piston are formed integrally.

3. An intensifier as claimed in Claim 1 or Claim 2, wherein the shuttle valve is reciprocable along a line coaxial with the axes of the ram and enlarged piston.

4. An intensifier as claimed in Claim 3, wherein the lost motion mechanism consists of a co-axial rod connected to valve members of the shuttle valve means and terminating in an enlarged head so located within a bore of the integral ram and enlarged piston, bore has abutment means at its opposite ends, that at the end of the ram delivery stroke the rod, and hence the shuttle valve members are pulled in the ram delivery direction to achieve change-over, and at the end of the ram retraction stroke, are pushed in the ram retraction direction to achieve change-over.

5. An intensifier as claimed in any preceding Claim, wherein the check valves associated with the high pressure chamber are spring-loaded ball valves.

6. An intensifier as claimed in any preceding Claim, wherein the valve members of the shuttle valve are poppet valves.

7. An intensifier as claimed in any preceding Claim, comprising one and preferably two coil compression springs which recoil upon ram movement halting to urge the shuttle valves on to, or off, their seats.

8. A fluid pressure intensifier substantially as hereinbefore described with reference to the accompanying drawings.