FR2730750A1 - Drag-line type excavator with hydraulic grab for working on water or ground - Google Patents

Abstract

The excavator has a grab (13) formed by a pair of half-shells (15) suspended at the end of a cable from a pivotable arm (9). The arm is mounted on a platform (1) which also carries a power source. At least one two-way jack (16) is associated with the grab, supplied with e.g. hydraulic power via one or more flexible conduits (17). The flexible conduits are secured to a fixed portion (14) of the grab structure to guide it relative to the axis of its suspension cable. The conduits are wound on a drum (19) mounted on the pivotable arm. A pressure control system regulates the fluid pressure within the conduits during winding and unwinding, and delivers pressurised fluid to operate the jacks.

Description

 The present invention relates to public works equipment and, more particularly, to equipment enabling earthworks to be carried out, by means of a clamshell bucket, suspended from carrier cables.

 The materials of the above type are designed to work in the terrestrial domain or also in the maritime or fluvial domain and can be considered as comprising the same general structural means in both cases.

 These means involve a platform on which are mounted different control structures, energy supply, winching, as well as a boom that can be adjusted in site. In the application to the terrestrial domain, such a platform is generally also mounted orientable on a vertical axis.

 The boom generally carries two pulleys at the head which are reserved for supporting and bending two cables supported by two winching installations. Beyond the boom head pulleys, the cables are connected to a clamshell grab and assume, vis-à-vis the latter, each a common function and a specific function.

 The common function concerns the support and the suspension of the clamshell which, by this means, can be subjected to a vertical displacement between the maximum elevation and the working level.

 The specific function corresponds, for one of the cables, to an open state of the clamshell and for the other, to a closed state. Thus, when the first cable alone supports the bucket, the latter opens or remains open, while it closes or remains closed when it is suspended only by the other cable.

 Such widely used materials can be considered satisfactory. However, putting them into service gives rise to a certain number of drawbacks.

 One of the first, and certainly one of the most important, is that the clamshell bucket is always suspended only at the end of a single cable, the mechanical strength characteristics of which consequently determine the capacities of intake, lifting and emptying.

 In many fields, such characteristics strongly limit the working capacity and lead to a multiplication of the lowering, setting, raising, emptying cycles.

 Another drawback is that, in the setting phase, the penetration force of the shells into the material is reduced, due to the need to tension the cable for closing the bucket, such tensioning correspondingly reducing the bearing force of the shells on the material, because of the relative relief which it induces.

 To reduce this drawback, it is known to multiply by hauling the action of the cable with, in return, an increase in the closing time.

 However, even with this arrangement, the entire weight of the bucket is never used for penetration into the material.

 A third disadvantage is that the small spacing of the two cables side by side does not allow effective control of the rotation of the bucket on the axis that these cables define. In some applications, the random orientation of the bucket poses problems that are difficult to overcome and requires particularly vigilant attention from the operator, who often has to bring together makeshift means, controlled manually by an assistant, to favor the proper orientation, both in the descent phase prior to setting, but also in the emptying phase.

 There are many cable means for opposing random rotation, but these means require one or more additional winders, of the elastic return type, which increase the space and maintenance requirements.

 The general problem which is thus posed lies in the observation that the technical means, generally used to produce such equipment, cannot be used to the full in the majority of intervention conditions, which increases the hourly rate of commissioning.

 The present invention aims to propose improvements to equipment of the above kind, in order to solve the general problem posed by reducing, or even eliminating, the drawbacks mentioned above.

 The improvements according to the present invention relate, more specifically, to the lifting and opening-closing control means of the clamshell and these improvements are designed so as to allow a relatively simple and rapid adaptation of a dredge of traditional design which can , if necessary, be reconstituted in its original structure.

 The improvements according to the present invention are aimed at efficient, robust, reliable technical means which can operate fully automatically without requiring the supervision of an aid or an operator on site independent of that responsible for operating the equipment.

To achieve the above objectives, the invention is characterized in that
- the bucket comprises for the control of the shells, at least one
double-acting cylinder whose energy supply is ensured by
at least one flexible hose unrollable from a retractor
rotation controlled at winding and rotation braked at
unfolding
- and the hose is linked to the structure of the bucket to ensure
orientation guidance function of the latter, with respect to
the axis defined by the cable.

 Various other characteristics will emerge from the description given below with reference to the appended drawings which show, by way of nonlimiting example, an embodiment of the subject of the invention.

 Figure 1 is a schematic elevation of a dredge according to the invention.

 Figure 2 is a partial schematic view, on a larger scale, of the dredge bucket in the closed position.

FIG. 3 is a transverse view taken, on a larger scale, along the line
III-III of figure 2.

 FIG. 4 is a transverse view, part in section, taken, on a larger scale, along the line IV-IV of FIG. 1.

 Figure 5 is a sectional elevation taken on the line V-V in Figure 4.

 Figures 6 and 7 are diagrams illustrating some of the technical means of the invention.

 According to Figure 1, the suspended clamshell dredge is shown in a land version and comprises a platform 1 mounted by a turret or the like 2 on a carrying frame 3 equipped with moving drive members 4. In the representation of FIG. 1, the members 4 are of the track type, but could of course be replaced by other running members, such as drive trains and / or directors.

 The turret 2 is intended to allow the rotation of the platform 1 on a vertical axis xx 'and over a partial or total angular range.

 The platform 1 supports a control cabin 5, a winching installation 6, a group 7 for supplying energy and carries, in the front part by a hinge pin 8, an arrow 9 whose adjustment in elevation can be predetermined or variable, being adjusted, for example, by means of cables 10.

 According to the invention, the arrow 9 carries at the head, preferably, two parallel pulleys 11 mounted on a common horizontal axis of rotation. The pulleys 11 are provided to support and allow the inflection of two cables 12 which are connected to the winching installation 6 advantageously comprising two flights of drum for the winding and the simultaneous unwinding of the two cables 12.

 I1 should be considered that an embodiment involving only a single cable 12 would not depart from the scope of the invention.

 Beyond the jib head pulleys 11, the cables 12 extend naturally vertically and ensure the suspension of a clamshell, of the shell type, generally designated by the reference 13. According to FIGS. 1 and 2, the bucket 13 comprises a carrying structure 14 to which the two cables 12 are linked and on the base of which are articulated two shells 15a and 15b which, in known manner, can occupy an open position, as illustrated by FIG. 1, or a closed position, according to FIG. 2, after a simultaneous rotation in the directions of the arrows f, placing them contiguously so as to delimit the useful volume of the bucket 13.

 According to the invention, the structure 14 preferably involves two means 16a and 16b for controlling the simultaneous opening-closing of the shells 15a and 15b. Such means 16 are constituted by energy transformers, preferably but not exclusively linear, which can be double-acting cylinders, electric or, more preferably, hydraulic. The transformers 16a and 16b are each supplied with energy by two conduits 17l, 172, from two hoses 17a and 171> which have the particularity of being physically positively linked to the structure 14 and, more particularly, to a lifting beam 18 that has this structure above the shells 15a and 15b. The lifter 18 extends orthogonally to the vertical axis yy 'which is defined by the alignment of the carrying cables 12, on either side of this axis and the hoses are linked to the lifter on either side of the axis yy '.

 The above provisions are to be considered, mutatis mutandis, in the case of a single cylinder or of two single-acting cylinders 16.

 The hoses 17a and 17b are, moreover, opposite the bucket 13, supported by a two-track reel 19 which is mounted on the boom 9, below the boom head pulleys 11 and at a distance of the latter such that, in all cases and whatever the level of the clamshell 13, the hoses 17a and 17b extend in a direction which is not parallel to that of the carrying cables 12 along the axis yy ' .

 The reel 19 has the constructive characteristic of being controlled in controlled rotation to the winding, in the direction of arrow 2 and in rotation braked during unwinding, that is to say in the opposite direction.

 The arrangements described above allow the following results to be obtained.

 The suspension of the bucket 13 is ensured by the two cables 12, so that its maximum load can be considered to be close to twice that of a traditional dredge, all other things being equal, and, of course, within the limits of tilting moment of the dredge.

 The connection established between the reel 19 and the lifter 18 makes the hoses 17a and 17b, or even the single hose 17, assume two distinct functions.

 The first is the transport of energy necessary for the operation of the transformer (s) 16a and 16b. The second is that of tie rods which are kept under relative tension by the positive rotation controlled in the raising phase and by the braked rotation in the lowering phase. Thus, the hoses 17a and 17b contribute to keeping the clamshell 13 in vertical movement without swaying, while occupying a predetermined orientation on the axis yy ', due to the attachment between the hoses 17a and 17b and spreader 18.

 The command to close the shells 15a and 15b is ensured positively by means of the transformers 16a, 16b, so that handling of materials which are difficult to remove or of a large mass of materials can be carried out and certainly, with a maximum loading capacity of the bucket 13.

 The implementation of the above means contributes to increasing, all other things being equal, the gripping capacities of the bucket 13 which can, moreover, be controlled in cycles at relatively high frequency, due to the fact that it is required to follow a vertical descent plane in which it can be released by gravity to have the fastest possible descent stroke.

 The above means have, moreover, the advantage of ensuring descending and ascending strokes free of swaying, while maintaining a predetermined orientation of the bucket 13, so as to allow commissioning under optimal conditions under the sole supervision of the operator occupying the cabin 5.

 Although this is not shown, it can be envisaged to make the spreader 18 orientable in its plane relative to the axis yy ', so as to offer a possibility of privileged orientation of the bucket 13. By orientation, it is appropriate to consider the relative displacement relative to the structure 14, given that the lengths of the hoses 17a and 17b remain, a priori, equal to each other, in the part between the lifter 18 and the reel 19, whatever the length unwound from the latter.

 In a preferred embodiment, the energy transformers 16a and 16b are of the double-acting hydraulic type. The hoses 17a and 17b are then of corresponding design and are wound on two parallel tracks 20a and 20b which are delimited by the reel 19, according to FIG. 4. The hoses 17a and 17b are, in such an example, connected to a joint turning 21 which materializes and defines the axis of rotation zz 'of the reel 19, in combination with a motor 22, preferably hydraulic, supported by a frame 23 forming part of or adapted on the arrow 9.

 In such an embodiment, the means for controlling the rotation of the reel 19 from the hydraulic motor 22, involve a circuit of the type of FIG. 6, comprising a pump 24 drawing from a tank 25 and connected to the input of the motor 22 via a supply line 26. The output of the motor 22 is connected to the cover 25 by a return line 27.

 Line 26 is controlled by a two-position distributor 28 which is associated with one or preferably two pressure relief valves 29. For reasons which emerge from the following, the distributor 28 is in the closed rest position in which nevertheless it establishes an intercommunication between line 26 and a connection 30 connecting the outlet ports of the pressure limiters 29 directly to the return line 27. The distributor 28 is in particular controlled by means of an electromagnet 31, for example, supplied upon commissioning to establish the continuity of line 26 and ensure the continuous supply of motor 22.

 The circuit according to FIG. 6 also comprises an intercommunication line 32 between the lines 26 and 27, downstream of the distributor 28. The intercommunication line 32 comprises a branch line 33 which is controlled by a distributor 34 at two states and in closed rest position. The control of the distributor 34 is ensured by an electromagnet 35 which is controlled in dependence relationship with the winching installation 6 ensuring the function of lowering the bucket 13. The bypass line 33 is connected downstream of the distributor 34 on the return line 27 with the interposition of a pressure limiter 36 having the particularity of being adjusted to a maximum pressure threshold lower than the threshold of the limiter (s) 29 which are responsible for discharging the excess fluid towards the line 27 supplied by pump 24.

 The circuit according to Figure 6 operates as follows.

 When the winching installation 6 is ordered to raise the bucket 13, the electromagnet 31 is supplied and pushes the distributor 28 into its open position. The hydraulic fluid supplied by the pump 24 is administered to the motor 22, the rotation of which causes the controlled rotation of the reel 19 responsible for gradually swallowing the unwound length of the hoses 17a and 17b concomitantly with the lifting of the shell bucket 13. In this way , the hoses 17a and 17b remain placed under tension and are capable of ensuring the dual function described above.

 When the winching installation 6 is controlled to authorize the descent by gravity of the bucket 13, the distributor 34 is controlled by the electromagnet 35 to establish the continuity of the bypass line 33. The motor 22, driven in rotation reverse via the reel 19 biased in rotation by the traction exerted on the hoses 17a and 17b by the fall by gravity of the bucket 13, then behaves like a pump sucking fluid through the line 27, to discharge it by line 26. The fluid, thus discharged, added to the fluid supplied by the pump 24, is evacuated to line 27 through the distributor 34 and the limiter 36 which fixes the pressure. The fluid necessary for the suction of the pump 22 is recycled towards the latter, while the excess is evacuated towards the tank by a calibrated valve 37. The pressure in the lines 26 and 32, fixed by the limiter 36, being much higher than the pressure in line 27 fixed by the valve 37, it follows that a couple of forces is necessary to rotate the motor 22 behaving as a pump. By reaction, this couple brakes the rotation of the reel 19.

 In this way, during the descent, the bucket exerts a traction on the hoses 17a and 17b which are tensioned by the braked rotation of the reel 19, so as to always assume their function of orientation tie rods of the bucket 13.

 According to one development, the motor 22 is associated with a brake 38 controlled by the release of the pressure prevailing in the line 27 and whose elastic clamping pressure is less than the setting of the valve 37. The circuit then further comprises a distributor 39 with two states and in the closed rest position, mounted in short-circuit of the valve 37 while being thus connected to line 33 and to connection 30.

According to this development, the following functional states may occur
- Distributor 28 closed - Distributor 39 closed
Lines 26 and 27 are at the setting pressure of the valve 37 and therefore
the motor 22 does not transmit any torque. The calibration pressure of the
valve 37 being greater than that for applying brake 38, the latter is
loose. The reel 19 is then free to rotate, for example to
facilitate any intervention.

- Distributor 28 open - Distributor 39 open
This situation is prohibited by the power supply of the electromagnets 31
and 35, because it would correspond to a rotation of the motor 22 with the brake
38 tight.

- Distributor 28 closed - Distributor 39 open
In this state, the pressure in lines 26 and 27 is zero and the brake
is tight. The reel 19 is then immobilized.

- Distributor 28 open - Distributor 39 closed
Line 26 is then at the setting pressure of the limiter 29 or 36, if
the electromagnet 35 is energized, while the line 27 is at the pressure of
calibration of the valve 37. In this case, the brake 38 is released and the motor
22 transmits a torque proportional to the pressure difference between
lines 26 and 27. The reel 19 then ensures the tension of the one or more
flexible 17a and 17b.

 In the case of application involving hydraulic energy, as described above, it is important to be able to ensure the winding of the hoses 17a and 17b in flexible conditions suitable for the reel 19 and its motorization means.

 FIG. 7 shows that, according to the invention, means are provided for causing the pressure in the hoses 17a and 17b to drop or cancel during the winding-unwinding phases. These means involve, for each energy transformer 16 and for the two chambers 401 and 4 2 that it comprises, in the case of a double-acting transformer, two non-return valves 41, and 412 which are placed at the entry of the chambers on the supply conduits, such as 17, and 172, constituting one or more hoses 17. The non-return valves 41, and 412 are of the type inversely piloted in opening, that is that is to say that the valve 41, is controlled in opening by the pressure prevailing in the conduit 172, while the valve 412 is controlled in opening by the pressure prevailing in the conduit 17,.

 In addition to these means, the conduits 17 and 172 are connected to a supply line 43 and to a return line 44 by means of a distributor with three positions 45 and with a central rest position. The constitution of the distributor 45 is provided so that in this rest position, it interrupts the supply line 43, while ensuring intercommunication between the conduits 17 and 172 and the return line 44.

 In this way, the transformer 16 remains supplied with pressurized hydraulic energy in the chambers 40, and 4 2, due to the presence of the non-return valves 41, and 412, while in the rest position, that is to say say no power in one direction or another, the distributor 45 maintains the conduits 17 and 172 in communication with the return line 44.

 According to another arrangement of the invention, provision is made to associate the reel 19 with an oscillating balance 50 which is mounted by means of two arms 51 on the axis zz ', in rotation braked by means of '' a double-effect oscillation damper 52 (Figure 5). The pendulum 50 delimits, by means of rollers 53, two passages 54a and 54b constituting two guides taking charge of the hoses 17a and 17b. The presence of the pendulum 50 makes it possible to absorb the variations in tension and angular orientation of the hoses 17a and 17b during the winding-unwinding phases corresponding to the lowering and raising cycles of the clamshell bucket 13.

 The invention is not limited to the example described and shown since various modifications can be made thereto without departing from its scope.

Claims (13)

 1 - Hanging clamshell dredge, of the type comprising a carrying structure surmounted by a platform (1) carrying energy supply means, control means, a tiltable boom (9) and a winching installation for at least one cable passing over a pulley (11) of boom head beyond which it carries a grab (13) which is provided with shells (15) controlled in open-close,  characterized in that  - the grab includes, for the control of the shells, at least one  double-acting cylinder (16) whose energy supply is ensured  by at least one flexible hose (17) which can be unwound from a reel  (19) controlled in rotation controlled by the winding and in rotation  slowed down  - And the hose is linked to the structure (14) of the bucket to ensure  orientation guidance function of the latter, with respect to  the axis defined by the cable.  2 - Dredge according to claim 1, characterized in that  - the grab (13) is suspended from two carrying cables (12)  parallel, guided at the head of the jib and wound on a winch (6)  double volley  - and the bucket has two jacks (16) supplied from two  flexible which are linked to the structure of the bucket.  3 - Dredge according to claim 1, characterized in that the reel (19) is carried by the arrow below the head pulley and at a distance as it defines, for the part of the hoses (17) s' extending out of the reel to the bucket, a direction that is not always parallel to that of the carrying cables.  4 - Dredge according to claim 1, 2 or 3, characterized in that the hoses (17) provide a supply of hydraulic energy and in that means are provided for canceling the pressure in the hoses during the winding-unwinding phases .  5 - Dredge according to one of claims 1 to 4, characterized in that the hoses are linked to the end parts of a lifting beam (18) forming part of the carrying structure (14) of the bucket and extending in a direction orthogonal to that of the carrying cables and on either side of the axis defined by the cable (s) (12).  6 - Dredge according to one of claims 1 to 5, characterized in that the hoses are connected to a rotary joint (21) coaxial with a motor (22) for driving in rotation with which it materializes the axis of the reel.  7 - Dredger according to one of claims 1 to 6, characterized in that the hoses (17) are supported at the exit of the tracks and substantially at the periphery of the reel by passing through two guides presented by a pendulum (50) oscillating on the axis of the reel.  8 - Dredger according to claim 7, characterized in that the balance is associated with a vibration damper (51) with double effect.  9 - Dredger according to claim 1, characterized in that the reel is associated with means for controlling the rotation controlled on the winding and in rotation braked during the unwinding, these means comprising a hydraulic circuit composed at least  - a pump (24) connected by a supply line (26) to the  motor (22) of the reel, which is connected by a line (27) of  back to the cover (25),  - a controlled distributor (28) controlling the supply line  (26) in combination with at least one pressure relief valve (29),  - an intercommunication line (32) established, downstream of the  distributor, between the supply line and the return line,  - a bypass line (33) established between the line  intercom and return line  - And a controlled distributor (34) controlling the bypass line  in combination with a pressure relief valve (36) set to a threshold  maximum pressure lower than that of the supply line.  10 - Dredger according to claim 9, characterized in that the distributor (28) of the supply line is controlled to open upon commissioning, while the distributor (39) of the bypass line, is of the type to closed rest position, and is commanded to open only when the clamshell descends.  11 - Dredger according to claim 9, characterized in that the circuit comprises for the motor (22) an elastic brake (38) hydraulically controlled in release, from the pressure of the return line (27) which includes a check valve -return (37) tared to a value greater than that of brake application.  12 - Dredge according to claim 11, characterized in that the circuit further comprises a distributor (39) mounted in derivation of the valve (37) on the return line (27), this distributor (39) being in the closed rest position and controlled by an electromagnet, so as never to occupy an open position when the distributor (28) occupies an open position.  13 - Dredger according to claim 4, characterized in that the means for canceling the pressure in the hoses comprise, at the inlet of the two chambers (4ou, 402) of the jack, two non-return valves (41l, 412) inversely piloted in opening and, at the inlet of the hoses, a distributor (45) with three positions establishing in its rest position, the simultaneous intercommunication of said hoses with the return to the cover (25).