GB2236149A - Generating fluid pressure from a head of liquid - Google Patents

Abstract

A method and apparatus for generating fluid pressure capable of doing useful work from the varying depth of liquid in, for example, a canal or river lock. The apparatus comprises a fluid pressure generating device having a compressible housing (20) in which the weight of liquid above the housing is resisted over a relatively small area by one or more rams or bellows devices. Accumulator means stores the fluid pressure generated by the rams or bellows until it is required to do work. The compressible housing recuperates when the liquid level in the lock is lowered. <IMAGE>

Description

ENERGY TRANSMISSION This invention relates to a method and apparatus for energy storage and/or transmission. A principal application of the method and apparatus is to the operation of locks on canals and rivers. Other applications are foreseen. Generally speaking, the invention may find application to many other situations in which the potential energy arising from a difference in height or depth of water (or other liquid) can be utilised for operating mechanisms or analogous purposes.

In the case of the operation of lock gates for canals and rivers, power-operated mechanisms have been provided to turn the lock gates themselves and indeed to operate the valves or sluices therein. Such arrangements are needed where, for commercial purposes, it is necessary that the gates are operated rapidly and with the minimum of effort on the part of the canal or river user. The mechanisms concerned use conventional power supplies, such as electric motors.

However, in remote areas there may not be a readily available power supply for the operation of such gates and equipment. Moreover, conventionally-designed mechanisms for performing tasks of the kind in question require maintenance, may be noisy in use, and (where an internal combustion engine is employed) may very well generate unacceptable pollution.

Accordingly, an object of the present invention is to provide a method and apparatus for energy/power transmission, applicable to the operation of canal/river lock gates and associated mechanisms, or to like apparatus, in which the potential energy arising from a change in water or other liquid depth is employed for actuation purposes, and/or offering other advantages in relation to matters discussed herein or generally.

According to the invention there is provided a method and apparatus as defined in the accompanying claims.

In a preferred embodiment, the difference in water height in a canal or river lock, commonly of the order of between 2 and 4 metres, is employed to generate a corresponding transmissible hydraulic pressure for actuation of one or more hydraulic rams. In the embodiment, the hydraulic pressure is generated by means of a pressure generation unit which is located at the base of the lock itself. The unit is a compressible structure and adopts an extended configuration when not immersed in water. On filling the lock, the device remains at the base of the lock and is compressed by the hydraulic pressure arising from the depth of water.This hydraulic effect is amplified by arranging that the hydraulic pressure is applied over a relatively large surface area of the compressible device, while it is resisted by a series of hydraulic rams, or pressure generators, which have a combined piston area greatly less than the area over which the water pressure acts. The hydraulic pressure thusgenerated is caused to energise an hydraulic accumulator, which thus stores the hydraulic pressure. A non-return valve prevents feed-back of the pressure. The thus-stored pressure and energy can be released, at will, by an operator, so as to actuate one or more corresponding cylinders connected to the canal or lock gates and/or the valves or sluices therein.

In the embodiment, the construction of the hydraulic pressure generating device comprises a series of stiffening ribs supporting the outer shell or skin of the device.

These ribs are connected by pins to the hydraulic pressuregenerating rams. These latter are, effectively, the master-cylinders. The slave cylinders can be double or single acting. In the case of the lock gates, the slave cylinders need to be double acting. In the case of the valves or sluices therein, they can be single-acting since a gravity-close arrangement can be adopted.

After the energy stored in the system, as thus described, has been employed for actuating the slave cylinders, the low pressure remaining within the hydraulic system can be used to re-expand the actuation unit, after the depth of water in the lock has been lowered, whereby the cycle can then be repeated by re-filling the lock, using the energy remaining stored in the actuator.

In the embodiments, the apparatus can be retro-fitted to existing canal and river locks, relatively easily. The hydraulic pressure-generating device can be placed in the lock by means of a barge with suitable block and tackle.

No significant modifications to the gates are required, and no significant appearance changes around the lock are needed.

Amongst other modifications to the embodiments which are contemplated are the use of the pressure-generating device to respond to water depth changes due to wave movements in a marine situation. In this way, it may well be possible to generate energy, for example in the form of electricity. In place of the hydraulic rams of the pressure generating device, a bag-type master cylinder arrangement might be employed. Alternatively, the rams could be arranged otherwise than vertically, by use of bell cranks connecting the stiffening ribs to the rams.

An embodiment of the invention will now be described by way of example with reference to the accompanying drawings in which Fig 1 shows a section through a canal lock showing a fluid pressure generating device in position on the base of the lock, with the lock relatively full of water; Fig 2 shows the situation in which the level of fluid in the lock has been lowered; Fig 3 shows, on a larger scale, a section through the fluid pressure generating device; Fig 4 shows a detail of the device of Fig 3; Fig 5 shows a plan view of the pressure generating device indicating the disposition of the fluid generating cylinders therein; Fig 6 shows a circuit diagram of the entire apparatus.

As shown in Figs 1 and 2, a canal lock 10 comprises side walls 12, 14 and a base 16 within which a body of water 18 is stored between gates, not shown.

At the base of the lock is located a fluid pressure generating device 20, to be more fully described below.

Referring now to Figs 3, 4 and 5, fluid pressure generating device 20 comprises a fixed base plate 22, a vertically movable upper plate 24, longitudinal H-section stiffeners 26, 28, transverse stiffening ribs 30, an upper shell or skin 32, and six master cylinders or hydraulic rams 34 disposed at the locations indicated in Fig 5.

Base plate 22 and upper plate 24 are interconnected in fluid-tight relationship by a peripheral bellows seal 36 which excludes the external water from the interior of device 20.

Rams 34 comprise clyinders 38 and pistons 40, these latter being pinned at 42 to the ribs 30.

It can now be seen that device 20 is, effectively, a compressible hollow fluid-tight chamber. Rams 34 can expand the chamber to the condition shown in Fig 2 under light internal hydraulic pressure. The weight of water is transmitted from the large area of shell 32, through ribs 30 to pistons 40, and thus to the hydraulic fluid within cylinders 38. It will be seen that the area, in sum, of the cylinders is very substantially less than the total area of shell 32, whereby the step-up in hydraulic pressure thus generated~ is very considerable.

Turning now to the hydraulic circuit of Fig 6, it will be seen that two such devices 20 are provided per canal lock. The rams 34 are connected in parallel to a common hydraulic line 44 connected through non return valves 46, 47 to accumulators 49, and thence to four valve blocks 50, 52, 54 and 56 controlling respective pairs of slave cylinders 58, 60, 62 and 64. Of these, cylinders 62 and 64 may be arranged to actuate the canal lock gates with cylinders 58 and 60 controlling the paddles or sluices thereof.

In use, the sequence begins in the Fig 2 position.

The residual hydraulic pressure within the rams 34 holds device 20 in its expanded or recuperated condition. On filling the lock to the Fig 1 condition, the device is compressed, as shown in Fig 1, and the weight of water resting on shell 32 causes rams 34 to generate a substantial hydraulic pressure which is communicated via non-return valve 47 to accumulator 49 where the hydraulic pressure compresses the inert gas in the device, and thereby stores the fluid at a relatively high pressure, for example at 1000 pounds per square inch. Valve block 56 and non-return valve 47 seal-off the pressure within accumulator 49. When desired, the pressure can be released by suitable actuation of the valves 50 to 56 to cause cylinders 58 to 64 to be actuated by the fluid pressure.

The reduced fluid pressure remaining in the system after such use is available to cause the rams 34 to recuperate from the Fig 1 to the Fig 2 condition, as mentioned above.

Interestingly, the above embodiment provides a simple means for utilising the potential energy available from a relatively small change in liquid height, such as the change in canal lock depth between the Fig 2 and Fig 1 positions, for the purpose of doing useful work. While in the embodiment, this work is directly related to the operation of canal lock equipment, other applications are contemplated. Indeed, it may well be convenient in certain circumstances to use this energy to pump water, for example to assist replacement of water lost in a canal system by repeated use of the canal lock gates.

In the above embodiment it is noteworthy that the fluid pressure generating device 20 is totally sealed and the system requires an absolute minimum of alteration to existing canal and river locks for retro-fitting purposes.

The hydraulic accumulator is of the gas filled diaphragm type which produces a constant pressure with change of volume. The high pressure accumulator 49 provides a source of pressure for actuating the slave rams. The downstream fluid from these is fed to the low pressure side of the system and stored in the low pressure accumulator 48. This provides a convenient means for extending the hydraulic rams and the platform when the depth in the lock has been reduced.

In the above embodiment the dimensions of the device 20 may, for example, be 25 feet by 6 feet 6 inches (plan view area as seen in Fig 5), with an estimated weight of steel structure loading the six rams of about 2 tons. The weight of water on this area at a depth of 5 feet is approximately 22 tons, whereby the laden weight on each of the centre two rams is about tons, and on each of the end rams about 3 tons. The ram stroke diameter for the centre rams is up to a maximum of about 4 inches and for the end rams up to a maximum of about 3 inches. For such an arrangement, a total displacement of fluid with two such fluid pressure generating devices might be approximately 427 cubic inches, with hydraulic pressures generated, in the unladen condition of 80 and 89 pounds per square inch for the end and centre rams respectively.

On the basis of a conservative figure of 1000 pounds per square inch available pressure from the device 20 in its laden condition, calculation shows that actuation of lock gates and their associated sluices is well within the capacity of the system. For example, on the basis of the above quantities, it can be expected that four operations of the gates and sluices can be effected from a single energy-storage stroke of the device 20.

Claims (11)

CLAIMS :

1 A method of energy storage and/or transmission comprising a) providing a fluid pressure generating device; and b) causing said device to be immersed in a liquid; characterised by c) causing the weight of liquid above the device, acting over a given area, t be resisted within the device by fluid pressure acting over a smaller area whereby a greater fluid pressure is generated inside the device than exists outside it; d) connecting said fluid pressure generated to a system for doing work; and e) reducing the depth of liquid above the device and allowing same to recuperate at a lower pressure before repeating the pressure generation step.

2 A method of energy storage and/or transmission characterised in that a fluid pressure generator immersed in a liquid generates a higher fluid pressure than exists within the liquid by differential area step-up means.

3 A method according to claim 1 or claim 2 characterised by the step of storing said fluid pressure generated, in accumulator means.

4 A method of energy storage and/or transmission substantially as described herein with reference to the accompanying drawings.

5 Apparatus for energy storage and/or transmission comprising a) a fluid pressure generator device; and b) said device being adapted to be immersed in a liquid; characterised by c) said device having means whereby the weight of liquid above the device, acting over a given area, is resisted within the device by fluid pressure acting over a smaller area whereby a greater fluid pressure is generated inside the device than exists outside it; d) said fluid pressure generator being connected to a system for doing work; and e) said device, on reducing the depth of liquid above it, being adapted to recuperate at the lower pressure thus generated, before repeating the pressure generation step.

6 Apparatus for energy storage and/or transmission comprising a fluid pressure generator adapted to be immersed in a liquid, said generator being adapted to generate a higher fluid pressure than exists within the liquid by differential area step-up means.

7 Apparatus according to claim 5 or claim 6 characterised by accumulator means connected to said fluid pressure generator to store fluid pressure generated thereby.

8 Apparatus according to any one of claims 5 to 7 characterised by said device comprising a compressible housing and one or more cylinder of bellows devices within the housing to resist the weight of said liquid.

9 Apparatus according to any one of claims 5 to 8 connected to a slave device for operating a mechanism of a canal of river lock gate.

10 Apparatus for energy storage and/or transmission substantially as described herein with reference to the accompanying drawings.

11 A device for generating fluid pressure characterised in that the device is adapted to be immersed in a liquid aWd to generate a higher fluid pressure than exists within the liquid by differential area step-up means.