GB2069146A

GB2069146A - Monitoring and controlling the operation of impulse mechanisms

Info

Publication number: GB2069146A
Application number: GB8103797A
Authority: GB
Original assignee: BSP International Foundations Ltd
Current assignee: BSP International Foundations Ltd
Priority date: 1980-02-08
Filing date: 1981-02-06
Publication date: 1981-08-19

Abstract

A hydraulic driver can be remotely controlled using monitoring means that comprises a series of switches 20 along the path of its hammer weight 8. The switches are connected to an array of light-emitting elements giving a remote display of the reciprocation of the weight. The switches also selectively operate a control valve solenoid of the pile driver so as to vary the stroke of the weight and provide an adjustable cushioning effect at the bottom of its stroke. <IMAGE>

Description

SPECIFICATION Monitoring and controlling the operation of impulse mechanisms This invention relates to pile drivers and other mechanisms in which-a weight is reciprocated to generate a series of impulses and it is concerned with the monitoring and control of the movements of the weight in such mechanisms.

It is known to provide remote control means for a fluid-pressure operated pile driver, in which a control valve is switched by sensing means adjacent the weight to give a predetermined stroke of the weight in a guide frame of the mechanism. It has also been proposed to employ alternative sensing means at different positions to be able to change the stroke of the weight by selection of one or other of said sensing means, but the effective use of such arrangement, like other systems in which the operator switches an external control valve to regulate the stroke, requires the operator to be able to observe continuously the operation of the mechanism.

According to one aspect of the present invention, there is provided for use with a pile driver or other impulse mechanism in which a weight is reciprocated on guides to produce a series of impulses, monitoring means for the movement of the weight on its guides, said means comprising a series of electrical sensing elements disposed along the path of reciprocation of the weight or a member displaced together with the weight to be actuated by the movement of said weight or member past them, and indicating means responsive to the actuation by the weight of said sensing elements for indicating the movement of the weight at a location remote from said path.

In such an arrangement, the sensing means may conveniently take the form of a series of proximity switches or trip switches at intervals along the path of the weight, and the switches can be used both to indicate the movement of the weight and to control an adjustment mechanism so as to regulate the stroke of the weight. For example, in a fluid-pressure operated driver an inlet valve controlling the flow of the pressure fluid can be changed over as a result of the operation of said switches so that by selection of suitably positioned switches to effect the changeover, the stroke of the weight and its impact force can be altered. At the same time, the actual movement of the weight on its guides, including overrun beyond a selected switching position, will be revealed by the sequential operation of the switches of the series in response to the continued movement of the weight.If the switches are suitably closely spaced it is possible to both observe and control the reciprocation of the weight relatively precisely without it being necessary to be in a position to see the weight itself.

The invention may be further utilised to measure the cumulative reciprocating movement of the weight over a series of strokes and to monitor the operation of the mechanism generally.

For example, from information about the acceleration pattern derived from a series of switches that occupy known positions on the guides it is possible to obtain a measure of the resistance experienced to each impulse generated by the weight, According to another aspect of the invention, there is provided a pile driver comprising drive means for reciprocating a weight on guides to produce a series of impulses, monitoring means for the movement of the weight on its guides comprising a series of electrical sensing elements disposed along the path of reciprocation of the weight or a member displaced together with the weight, to be actuated by the movement of said weight or member past them, and indicating means responsive to the actuation by the weight of said sensing elements for indicating the movement of the weight, control means for the drive means being operable to adjust the stroke of the weight and being arranged to be selectively actuated by said electrical sensing elements.

The invention will be described by way of example with reference to the accompanying drawings, in which: Fig. 1 illustrates a hydraulically operated pile driver to which the invention is applied in this example, and Fig. 2 is a block diagram of the control arrangement according to the invention for said pile driver.

The pile driver shown in Fig. 1 comprises a guide frame 2 suspended from a cable sling 4 and having its lower end surrounding the head of a pile 6 to be driven. A hammer weight 8 is reciprocable in the guides 10 by hydraulic cylinders 12 to produce a series of driving impulses on a drive cap 14 mounted on the top of the pile and also slidable on the guides. The operation of the weight is controlled by a hydraulic pilot valve 1 6 that acts on pressure inlet valves (not shown) in the cylinders and that is itself operated by a solenoidoperated valve 1 8. Both the pilot valve and the solenoid valve are mounted on the driver frame 2, which may be remote from an operating station from which power is supplied to the driver and the operation of the driver is controlled and monitored.

Mounted on the frame, adjacent the path of the weight, is a series of switches, in this specific example eighteen vertically spaced proximity switches 20 spaced some 7.5 cm apart. Electrical connections extend from these switches to the operating station, at which there is located the control and monitoring circuitry indicated in Fig. 2.

The main upper group of the switches are connected to an upper stroke select unit 22 of the control circuit, while the smaller remaining group of switches, consisting of the bottom three switches, are connected to a lower stroke select unit 24. Both select units are connected through a T.T.L. unit 26 and an output interface 28 to the solenoid of the pile driver solenoid valve 1 8. The upper stroke select can actuate changeover of the pilot valve 16 so that the supply of pressure fluid to the cylinders is stopped and the weight is allowed to fall, while the lower stroke select determines the changeover of the pilot valve to allow pressure fluid into the cylinders again to raise the weight.

The individual switches are also connected to respective elements of an 1 8 element l.e.d.

columnar array 30 at the operation station, and to a voltage adding circuit 32. Both the voltage adding circuit and the T.T.L. unit 26 are driven by a stabilised voltage supply 34.

In operation, as the weight 8 moves along its guides it will close successive proximity switches 20 so that at the operating station there is a simultaneous display of its movement of the l.e.d.

array 30 and the corresponding inputs in the upper and lower stroke select units 22, 24 are successively put in circuit. The operator can choose the required changeover points for switching the pilot valve by selecting the operative input lines of the upper and lower stroke select units, so that changeover is actuated when the proximity switch connected to the selected input line is closed.

The choice of upper stroke select input will determine the height to which the weight rises on its guides, while the choice of the lower stroke select will allow the optimum moment for reversing the cylinder control valves to be chosen, so as to minimise the swell time of the weight after impact, in accordance with the driving conditions being experienced.

It will be understood that the reversal of movement of the weight does not occur simultaneously with the switching of the pilot valve, due principally to the inertia effects. The l.e.d. array 30 operates independently of the stroke select units, however, and allows the operator to see the actual movement of the weight.

A more detailed monitoring of the movement of the weight and its effect can be obtained by use of the voltage adding circuit 32 which like the l.e.d.

array has a series of individual inputs from the, or at least some of the, proximity switches to produce an output dependent upon the cumulative operation of the switches, or at least some of the switches, during a reciprocatory cycle. The adding circuit 32 may have connections 34 to any of a variety of conventional display and/or recording instruments such as oscilloscopes, data recorders and u.v. recorders.

Various forms of information may be obtained.

For example there may be a trace provided of the movement of the weight against a time base. By analysis in particular of the movement of the weight near the bottom of its stroke it is possible to get a better measure of driving weight velocities and impulse energies than can be obtained by direct visual observation. Such data is of use not only in monitoring the operation of the driver and the resistance to penetration of the pile, but also in checking the load-bearing capacity of the pile which is affected by the nature of the material into which it is driven.

There is also a counter 36 in parallel with the solenoid of the solenoid valve 1 8 to give a cumulative count of the impulses during the operation.

The invention can be applied to impulse generating mechanisms of many different forms, including mechanisms powered by other means than pressurised fluid and intended for purposes other than pile driving. Although it has uses in other situations, it has particular application to installations in which an operator is unable to observe easily the movement of the weight producing the impulses. This may occur in pile driving installations when the pile driver is required to operate under the surface or in a position that is inconvenient or even dangerous for the operator. The invention then allows the operator to be placed sorne considerable distance from the pile driver without hindering his ability to operate the driver. As a specific example, the invention is particularly suited to monitoring and controlling the operation of a pile driver at considerable depths underwater: such a driver is described in our patent application filed simultaneously herewith and to which reference can be made for a more detailed disclosure of the construction of the driver illustrated herein.

The use of a number of spaced switches to adjust the operation of an impact mechanism is able to offer more consistent control than known time-responsive control means which are susceptible to various operating factors. An added benefit of the provision of a multiplicity of monitoring elements that can also be used for the control of the mechanism is that if one switch fails it may be possible to use an adjacent switch without affecting the operation of the mechanism too seriously, and costly down-time can then be avoided.

Claims

1. Monitoring means for measuring the movement of the weight in a pile driver or other impulse mechanism in which said weight is reciprocated on guides to produce a series of impulses, said monitoring means comprising a series of electrical sensing elements disposed along the path of reciprocation of the weight or a member displaced together with the weight, to be actuated by the movement of said weight or member past them, and indicating means responsive to said actuation of the sensing elements for indicating the movement of the weight at a location remote from said path.

2. Monitoring means according to claim 1 wherein the sensing means comprise a series of proximity switches or trip switches at intervals along the path of the weight.

3. Monitoring means according to claim 1 or claim 2 wherein means are provided to produce an output indicative of the cumulative operation of at least some of said switches during a reciprocatory cycle of the weight.

4. Monitoring means according to any one of claims 1 to 3 comprising means for measuring the cumulative movement of the weight over a series of impulses.

5. Monitoring means according to any one of the preceding claims comprising means for counting the reciprocating cycles of the weight.

6. Monitoring means according to any one of the preceding claims comprising means for producing a time-based trace of at least a part of the movement of the weight.

7. A pile driver comprising monitoring means according to any one of the preceding claims and wherein an inlet control valve for a pressure fluid actuating medium of the driver is arranged to be changed over selectively by the operation of different ones of said electrical sensing elements.

8. A pile driver according to claim 7 wherein said electrical sensing elements are operable to changeover said control valve adjustably to respectively determine the rise of the weight and provide an adjustable cushioning effect for the fall of the weight.

9. A pile driver according to claim 8 wherein respective groups of said switches are arranged to control said respective adjustments for the reciprocation of the weight.

10. A pile driver comprising drive means for reciprocating a weight on guides to produce a series of impulses, monitoring means for the movement of the weight on its guides comprising a series of electrical sensing elements disposed along the path of reciprocation of the weight or a member displaced together with the weight, to be actuated by the movement of said weight or member past them, and indicating means responsive to the actuation by the weight of said sensing elements for indicating the movement of the weight, control means for the drive means being operable to adjust the stroke of the weight and being arranged to be selectively actuated by said electrical sensing elements.

1 A pile driver according to claim 10 wherein said control means is operable to provide an adjustable cushioning effect for the fall of the weight.

12. A pile driver provided with monitoring means constructed and arranged for use and operation substantially as described herein with reference to the accompanying drawings.

12. Monitoring means for use with a pile driver or other impulse mechanism, constructed and arranged for use and operation substantially as described herein with reference to the accompanying drawings.

13. A pile driver provided with monitoring means constructed and arranged for use and operation substantially as described herein with reference to the accompanying drawings.

New claims or amendments to claims filed on date of issue of search report.

Superseded claims 1-13.

New or amended claims:

1. Means for monitoring the movement of a weight in a pile driver or other impulse mechanism in which said weight is reciprocated on guides to produce a series of impulses, said monitoring means comprising a series of electrical sensing elements disposed along the path of reciprocation of the weight or a member displaced together with the weight, to be actuated by the movement of said weight or member past them, and indicating means responsive to said actuation of the sensing elements for indicating the movement of the weight at a location remote from said path.

2. Monitoring means according to claim 1 wherein the sensing elements comprise a series of proximity switches or trip switches at intervals along the path of the weight.

3. Monitoring means according to claim 1 or claim 2 wherein means are provided to produce an output indicative of the cumulative operation of at least some of said sensing elements during a reciprocatory cycle of the weight.

8. A pile driver according to claim 7 wherein said electrical sensing elements are operable to changeover said control valve adjustably to determine the rise of the weight.

9. A pile driver according to claim 8 wherein respective groups of said sensing elements are arranged to control respective adjustments for the start of a rising movement of the weight and the termination of said rising movement.

11. Monitoring means for use with a pile driver or other impulse mechanism, constructed and arranged for use and operation substantially as described herein with reference to the accompanying drawings.