GB2061463A - Pressure Fluid Medium Power Supply - Google Patents

Abstract

A pressure fluid medium power supply module comprises a main flow port P, a main return port T, and a combination of a pressure- compensated flow control means 3 and a pressure reducing means 4 connected to receive pressure fluid from the main flow port P. The pressure-compensated flow control means 3 is arranged to deliver fluid up to a predetermined flow rate, and the pressure reducing means 4 is arranged to deliver fluid up to a predetermined pressure. An auxiliary flow port REG 1 delivers fluid from the said combination to an appliance, and an auxiliary return port T1 receives fluid returned from such an appliance, and delivers the fluid to the main return port T. <IMAGE>

Description

SPECIFICATION Pressure Fluid Medium Power Supply This invention relates to pressure fluid medium power supply, and is particularly although not exclusively concerned with hydraulic power supply in underground mines.

In a mining environment, there are usually many large hydraulic machines, working at high pressures and flow rates. Miners are also supplied with various hand-held tools, for use with lower power supplies. Although miners may be instructed to use the hand tools with specific supplies, it is often the case that a supply of correct relatively low rating is not conveniently to hand. Then, either the tool has to be adapted to work at the pressure of a conveniently located high powered machine, or an individual power pack has to be provided for the tool. In practice, miners frequently connect hand-tools to supply lines of machines working at pressures and flow rates far in excess of those specified for the tool.

Thus, the tool is highly overpowered, and accidents, such as broken wrists, can occur.

The present invention aims to alleviate this disadvantage.

According to one aspect of the present invention, there is provided a pressure fluid medium power supply module comprising a main flow port, a main return port, a combination of a pressure-compensated flow control means and a pressure reducing means connected to receive pressure fluid from the main flow port, the pressure-compensated flow-control means being arranged to deliver fluid up to a predetermined flow rate and the pressure reducing means being arranged to deliver fluid up to a predetermined pressure, an auxiliary flow port for delivering fluid from said combination to an appliance when connected to the auxiliary flow port, and an auxiliary return port for receiving fluid returned from such an appliance and delivering the fluid to the main return port.

Preferably, a non-return valve is fitted in series with the main return port, the main flow port or the auxiliary return port, to guard against incorrect connection of the module.

The pressure-compensated flow control means and the pressure reducing means may be combined in a single integral unit, or may be arranged as a series combination of distinct units.

In an advantageous arrangement, the flow control and pressure reducing means are in the form of cartridges concealed within a positively secured housing, such that they are generally inaccessible on site, and adjustment of the cartridges necessitates dis-assembly of the housing in a workshop.

The module may be attached to high-power apparatus, to provide lower power supply for hand-held tools and the like. Alternatively, a plurality of modules may be disposed at strategic points around a mine, such that tools may be connected at these points as desired.

To assist in understanding the invention and to show how it may be carried out, two embodiments thereof will now be described, by way of example, with reference to the accompanying diagrammatic drawings, in which: Figure 1 is a circuit diagram of a hydraulic power supply module providing a bank of three regulated supply sections; Figure 2 is a plan view of one physical example of the module; Figure 4 is a side elevation onto the side A of Figure 2; Figure 5 is an end elevation onto the end C of Figure 2; Figure 6 is a sectional view of part of a modified hydraulic power supply module; and Figure 7 is a circuit diagram thereof, The hydraulic power supply module 1 shown in Figure 1 is arranged to provide three regulated outputs. A main flow port P and a main return port T are for connection to the hydraulic circuit of a relatively high power machine.A non-return or check valve 2 in the main return circuit protects against incorrect connection at the main ports P and T.

Each of three similar sections of the module 1 comprises a pressure-compensated flow control cartridge 3, connected to receive hydraulic fluid from the main flow port P, and a pressure reducing cartridge 4 connected to receive fluid delivered from the flow control cartridge 3. As is well known, each pressure-compensated flow control cartridge 3 comprises a variable diameter orifice, which can be adjusted to give a predetermined flow rate. The pressure at the inlet to the orifice is compensated to be a predetermined value, whereby the flow rate to the orifice is fixed for a given diameter. Thus, the cartridge 3 may receive hydraulic fluid at widely differing pressures and flow rates over a large range, and output the fluid at a predetermined flow rate.The pressure reducing cartridge 4 receives fluid from the flow control cartridge 3, and delivers the fluid at a predetermined pressure to an auxiliary flow port REG 1, etc. Thus, at this port there may be provided a hydraulic power supply which is at a predetermined pressure and flow rate. A hand-held tool, for example, may be connected to the auxiliary flow port REG 1, etc., and an auxiliary return port T1, etc., from which the fluid is returned to the main return port T.

Excess fluid at the pressure reducing cartridge 4 is led away to the port T, as indicated by dashed lines, to depressurise the cartridge.

Gauging ports G1, etc., are provided for monitoring purposes only. Thus, for example, port G1 monitors pressure in the simple feedback path indicated in dashed lines, which feedback path is used to regulate pressure in the respective cartridge 4.

By appropriate choice of ratings of the cartridges 3 and 4, regulated hydraulic power supplies at desired rated values may be provided on the three flow ports REG 1, REG2, and REG3.

Pressure-compensated flow control cartridges and pressure reducing cartridges are well known in the art, and may readily be obtained at various ratings. An advantage of placing the flow control cartridge 3 upstream of the pressure reducing cartridge 4 is that the latter need only be capable of handling a predetermined flow rate. Only the flow control cartridge needs to be able to handle a full range of flow rates and pressures.

One example of the physical construction of the module 1 is shown in Figures 2 to 5. The three pairs of cartridges 3 and 4 are mounted in a housing 5, together with the various ports P, T, REG 1 to REG3, T1 to T3, and G1 to G3. A cover (not shown) is positively secured about the projecting cartridges 4, to complete the housing.

The housing is clearly labelled with the rated values of the various regulated outputs. The housing is arranged to be generally tamper proof, such that it is generally impracticable for an operator to change any one of the regulated pressures and flow rates of the module 1. Such adjustments are carried out in a workshop, by disassembly of the housing 5 and adjustment or replacement of the required cartridge(s).

The module 1 may be secured to a high power machine, where the ports T and P are connected to the hydraulic circuit of the machine. It will be appreciated that the module may readily be varied to provide any desired number of regulated supplies. In an advantageous arrangement, a plurality of modules such as 1 are arranged at strategic points around a mine, so that power for hand tools may be provided wherever required. In such a case, check valves such as 2 are then placed in the branch return lines leading from the auxiliary return ports T1 etc., rather than in the main return line.

By way of numerical Examples, the flow control cartridges 3 may be arranged to deliver fluid at about 2000 psi, the pressure reducing cartridges 4 being regulated to provide pressures at between 1000 and 1500 psi. The auxiliary ports REG 1, 2 and 3 may provide fluid at flow rates of, for example, 27, 45 and 56 litres per minute, respectively.

In the embodiment illustrated in Figures 1 to 5, each section comprises two separate cartridges 3 and 4, which is convenient because such cartridges are obtainable as stock items.

However, if desired, two cartridges 3 and 4 may be combined into a single cartridge, requiring special manufacture. Instead of providing the items 3 and 4 as cartridges, the components thereof may be built integrally into the module 1, if it is not desired to provide interchangeability.

Although the embodiments have been described above with reference to hydraulic circuits, it will be appreciated that the invention is equally applicable to any pressure fluid medium, such as a pneumatic supply.

It may be appreciated that, particularly in a mining environment, the illustrated module 1 may provide extremely important safety features.

Because the supply is properly regulated, there is little risk of accident due to overpowering of tools.

The housing is clearly marked with regulated flow rates and pressures. Because the housing is substantially tamper proof, there is little risk of an operator being able to increase the rating of a given section, thereby overpowering a tool.

An example of an embodiment in which the cartridges 3 and 4 are combined into a single integral unit is illustrated in Figures 6 and 7.

The single cartridge 8 shown in Figure 6 is intended to replace the series combination of two cartridges 3 and 4, as illustrated in the Figure 1 embodiment. The cartridge 8 has a body 9 formes with a hydraulic fluid inlet port P8, an auxiliary regulated outlet port REG8, and with a central bore 10. A spool A is slidably mounted in the bore 10, and is resiliently biased into an end position by means of a spring D. The spool A is itself formed with a bore in which a spool C is slidably mounted, being resiliently biased into a respective end position by means of a spring B.

A duct 11 leads from the inlet port P8 to a first aperture 12 in the side of the spool A. A branch duct 18 communicates between the duct 11 and the top (as seen in Figure 6) of the bore 10, above the top of the spool A. The first aperture 12 in the side of the spool A communicates with a chamber 1 3 defined therein, by the inside walls of the spool A and opposite end portions of the spool C.

A second aperture 14 in the wall of the spool A also communicates with the chamber 13 and with a duct 1 5 which leads to the auxiliary regulated outlet port REG8 via an orifice E. A duct 1 6 communicates between the outlet orifice REG8 and a chamber 17 defined at the lower end of the bore 10, below the spools A and C, as seen in Figure 6.

A chamber 19 defined above the spool C communicates via an aperture in the wall of the spool A with an annular chamber 20 provided therein. A duct 21 communicates with the chamber 20 and with a leakage orifice 22.

Operation of the cartridge 8 is as follows.

Hydraulic fluid enters the inlet port P8 and is fed via the duct 11 to the chamber 13, and thence via the duct 1 5 to the orifice E. Hydraulic fluid is also fed by the duct 1 8 to the upper portion of the bore 10, above the spool A. As fluid from the duct 1 5 passes through the orifice E, it suffers a loss in energy which is reflected as a drop in pressure.

Thus, a slightly reduced pressure obtains at the regulated output port REG8, and, via the duct 16, in the chamber 17. Thus, the full inlet pressure is sensed at the top of spool A, and the slightly reduced pressure is-sensed below the spool A.

Under normal conditions, the slightly reduced pressure in the chamber 17, together with the spring force of the spring D, keeps the spool A in balance, in the illustrated position, against the pressure at the top of the spool A.

If the flow through the orifice E increases above a desired level, then the pressure drop therethrough will become greater, and the reduced pressure obtaining in the chamber 17, together with the force of the spring D, will no longer be able to balance the spool A. Therefore, the spool A will move downwardly to compress spring D, and thereby restrict the flow path of fluid through the aperture 12, chamber 13 and aperture 14, at the illustrated points X and Y.

When the flow rate through the orifice E falls back to the predetermined desired value, then the pressure drop across the orifice E will decrease, and the spool A will move up again into the illustrated position, under the influence of the higher pressure in the chamber 1 7 and the force of the spring D.

If the absolute pressure at the auxiliary port REG8 should rise above a predetermined level (determined by preloading of the spring B), then the spool C will be forced upwardly as seen in Figure 6 (because of the corresponding pressure obtaining in the chamber 17), thus compressing spring B. Flow through the aperture 12 is thereby restricted at the illustrated point Q, until the pressure reverts to the predetermined desired level, when the spool C will be returned by the force of the spring B.

Thus, it may be appreciated that the cartridge 8, as illustrated in Figure 6 and as represented schematically in Figure 7, serves both as a pressure-compensated flow control means and as a pressure regulating means.

Claims (11)

Claims

1. A pressure fluid medium power supply module comprising a main flow port, a main return port, a combination of a pressure compensated flow control means and a pressure reducing means connected to receive pressure fluid from the main flow port, the pressure compensated flow-control means being arranged to deliver fluid up to a predetermined flow rate and the pressure reducing means being arranged to deliver fluid up to a predetermined pressure, an auxiliary flow port for delivering fluid from said combination to an appliance when connected to the auxiliary flow port, and an auxiliary return port for receiving fluid returned from such an appliance and delivering the fluid to the main return port.

2. A module according to claim 1, wherein said flow control means and said pressure regulating means comprise respective discrete units.

3. A module according to claim 1, wherein said flow control means and said pressure regulating means are combined as a single integral unit

4. A module according to claim 2 or 3, wherein the or each said unit is in the form of a cartridge.

5. A module according to any preceding claim, comprising a plurality of parallel sections each comprising a flow control means, a pressure regulating means, and auxiliary flow and return ports as aforesaid.

6. A power supply module substantially as hereinbefore described with reference to Figure 1, Figures 1 to 5, or Figures 6 and 7 of the accompanying drawings.

7. Hydraulically operated apparatus provided with a module according to any preceding claim, arranged as a power take-off module.

8. A mining installation provided with at least one module according to any one of claims 1 to 6 or with apparatus according to claim 7.

9. A mining installation provided with a power circuit comprising a plurality of modules according to any one of claims 1 to 6.

10. A method of providing power for a hydraulic tool, the method comprising the steps of connected the tool to a hydraulic power supply via a module according to any one of claims 1 to 6.

11. Any novel method, feature or combination of features disclosed herein.