EP0926300B1 - Control apparatus for the vibratory amplitude of a vibrator with variable imbalance - Google Patents

Abstract

The vibrator has an accelerometric detector (A) experiencing vibrations created by vibrator and a processor (CA) deducing from the measured data a value representing the safe threshold of vibration. This value and a set value (S) are applied to a processor (PC) that controls the displacement of the dephasing mechanism and the speed of the drive.

Description

The present invention relates to a device for the controlled control of the frequency and / or amplitude of the vibrations of a variable moment vibrator usable for sinking or sinking objects in the ground.

We know that the very principle of sinking by vibration is to put the ground vibrating through the object to be pushed in. In particular, in weakly coherent soils, there is a fluidization of the soil which allows the insertion of the profile under its own weight and that of the vibrator which cap.

Usually, the vibrators used for driving involve at least two eccentric flyweight trains each comprising at least two eccentric weights rotatably mounted around shafts joined to two respective gears which mesh with each other so as to rotate in direction reverse one with respect to the other, under the effect of a motorization which can understand one or more engines.

The variation of the vibratory moment generated by the two flyweight trains is obtained by means of a phase shifter capable of generating an angular phase shift variable between the rotational movements of the two flyweight trains.

It turns out that from the sinking place propagate vibrations which the intensity can be harmful for neighboring constructions, in particular for loosely bonded masonry or premises housing vibration sensitive equipment such as measuring devices and / or computers.

The invention therefore more particularly aims to permanently master the amplitude of the vibrations so as to remain below a threshold of harmfulness of vibrations, this threshold being variable depending on the nature of the soil, that of the objects to be charged and, possibly, that of the installations to protect. It starts from the observation that according to the laws of physics, the harmfulness of the vibrator, with regard to vibration emissions, depends of the vibrational energy emitted, and consequently of the product of the amplitude by frequency.

It therefore proposes a slave control device involving the minus an accelerometric detector positioned so as to be directly or indirectly subject to the vibrations generated by the vibrator, means to deduce a value representative of the harmfulness of vibrations from accelerometric data delivered by the accelerometric detector, means for entering a set value, and processing means electronics associated with actuation means acting on the control of motor speed variation and therefore on the frequency of vibrations and / or phase shift of the phase shifter so as to maintain the value representative of the harmfulness of vibrations at a level less than or equal to the setpoint.

Thanks to these provisions, following some preliminary tests carried out on the site, the operator can determine a setpoint which, once entered guarantees the establishment of a vibration whose amplitude is sufficient for the sinking but remains below the harmfulness threshold vis-à-vis neighboring sensitive installations. Likewise, these tests will make it possible to determine and memorize a noxiousness / amplitude of vibrations and / or frequency law vibrations, this law then being used by the control device slave to adjust the amplitude and / or frequency of the vibrations so as to keep the harmfulness of vibrations at a level less than or equal to the value of setpoint.

Advantageously, the accelerometric detector is placed on the carcass vibrating of the vibrator. In this case, this detector can be connected to the means electronic processing by a wired link.

However, the invention is not limited to this solution. Indeed, the device according to the invention can involve an accelerometric power station equipped with electronic processing means, intended to be installed at the level of the structure to be protected. In this case, the transmission between the central accelerometric and electronic processing circuits can be ensured by any known remote transmission means such as wired link, radio, etc ..

Les figures 1 et 2 sont deux coupes schématiques, respectivement axiales et transversales d'un vibrateur à moment variable ;

La figure 3 est une coupe axiale schématique illustrant le principe général d'un déphaseur ;

La figure 4 est un schéma de principe du circuit de commande asservi du déphaseur.

Embodiments of the invention will be described below, by way of nonlimiting examples, with reference to the appended drawings in which:

Figures 1 and 2 are two schematic sections, respectively axial and transverse of a variable moment vibrator;

Figure 3 is a schematic axial section illustrating the general principle of a phase shifter;

Figure 4 is a block diagram of the phase shift control circuit.

In the example shown in Figures 1 and 2, the vibrator comprises two trains 1, 2, of eccentric weights rotatably mounted by means of shafts A ₁ , A ₂ , A _n , A ' ₁ , A' ₂ , A ' _n , parallel to a transverse axis XX 'and the ends of which engage in bearings carried by two parallel flanges 3, 4 constituting the two lateral sides of a housing 5.

Each of the weights M, M 'is associated with a pinion P arranged and dimensioned so that the pinions P associated with the same train 1, 2 weights M, M 'mesh with each other, in successive pairs.

In Figure 1, there are shown two trains 1, 2 of weights M, M ' each comprising a pair of counterweight assemblies M, M '/ pinion P shown in solid lines, the assembly partially represented in lines interrupted indicating the mode of implantation of another couple.

The rotational drive of the two trains 1, 2 of weights M, M 'is ensured by means of a variable speed motorization comprising two hydraulic motors H ₁ , H ₂ mounted on the flange 3 at one of the ends of the housing 5.

These two motors H ₁ , H ₂ drive two respective parallel output shafts passing through bearings integral with the flanges 3, 4 and which each carry two coaxial pinions P ₁ , P ₂ - P ₅ , P ₆ .

The pinion P ₁ meshes with the pinion P integral with the flyweight M 'to perform the rotational drive of the train 2.

The pinion P ₆ meshes with the pinion P secured to a flyweight M to perform the rotational drive of the train 1.

• un arbre menant portant un pignon P₃ engrenant avec un pignon P₅ solidaire de l'arbre de sortie du moteur H₂, et
• un arbre mené portant un pignon P₄ engrenant avec un pignon P₂ solidaire de l'arbre de sortie du moteur H₁.

To generate a variation in amplitude of the vibratory moment, the vibrator further comprises a hydraulic phase shifter 7 comprising:

• a driving shaft carrying a pinion P ₃ meshing with a pinion P ₅ secured to the output shaft of the motor H ₂ , and
• a driven shaft carrying a pinion P ₄ meshing with a pinion P ₂ secured to the output shaft of the motor H ₁ .

Of course, the invention is not limited to this arrangement: The pinion P ₃ could for example mesh with any one of the pinions P associated with the flyweight M of the train 1, while the pinion P ₄ could mesh with one any of the pinions P associated with the flyweights M 'of train 2.

As shown in Figure 3, the phase shifter 7 consists of a structure fixed 9, partly cylindrical, integral with the flanges 3, 4.

• un arbre central épaulé (arbre menant 6) qui porte, au niveau de son extrémité adjacente au flasque 4, le pignon P₃,
• un arbre tubulaire (arbre mené 8), monté rotatif autour de l'arbre épaulé 6 et qui porte, axialement décalé par rapport au pignon P₃, le pignon P₄.

Inside this structure 9 are rotatably mounted two coaxial shafts, namely:

• a shouldered central shaft (driving shaft 6) which carries, at its end adjacent to the flange 4, the pinion P ₃ ,
• a tubular shaft (driven shaft 8), rotatably mounted around the shouldered shaft 6 and which carries, axially offset with respect to the pinion P ₃ , the pinion P ₄ .

At the cylindrical part 10 of the structure 9, the tubular shaft 8 comprises a cylindrical inner surface successively having a smooth part 11 and a threaded part with helical teeth 12.

This cylindrical interior surface delimits, with a cylindrical surface of the shouldered shaft 6, an annular space 13 closed, on one side, by a bearing 14 ensuring the rotary and sealed mounting of one of the two shafts 6, 8 relative to the other and, on the other side, by a bottom 15 integral with the shaft 8 through which passes the shaft 6 with seal.

The cylindrical surface of the shaft 6 successively comprises a smooth part 16 and a threaded part 17 with helical teeth.

• une surface extérieure cylindrique comportant une partie lisse 21 qui coulisse avec étanchéité sur la partie lisse 11 et une partie filetée 22 qui engrène sur la partie taraudée 12 ;
• une surface intérieure cylindrique comprenant une partie lisse 23 qui coulisse avec étanchéité sur la partie lisse de l'arbre 6 et une partie taraudée 24 dont les dentures hélicoïdales sont en prise sur les dentures de la partie filetée 17.

Inside the annular space 13 is disposed an annular piston 20 comprising:

• a cylindrical outer surface comprising a smooth part 21 which slides with sealing on the smooth part 11 and a threaded part 22 which meshes on the threaded part 12;
• a cylindrical inner surface comprising a smooth part 23 which slides with sealing on the smooth part of the shaft 6 and a threaded part 24 whose helical teeth are engaged on the teeth of the threaded part 17.

The space E ₁ between the piston 20, the bottom 15 and the two shafts 6, 8, constitutes a first working chamber (main working chamber) into which a hydraulic fluid can be admitted thanks to an axial channel 25 produced in tree 6.

This axial channel 25 opens into a rotary joint 26 provided at the end of the shaft 6 and the fixed part of which is integral with the structure 9. This fixed part comprises a coupling sleeve 27 to which the conduit of a hydraulic phase shift control circuit.

Similarly, the space E ₂ between the piston 20, the bearing 14 and the two shafts 6, 8, constitutes a second working chamber into which hydraulic fluid can be admitted by virtue of an axial channel 28 produced in the shaft 6.

This channel opens into a rotating joint 29 provided at the end of the shaft 6 and of which the fixed part which is integral with the structure 9 constitutes a sleeve fitting 30.

The operation of this phase shifter is then as follows:

In the absence of pressure inside the working chambers E ₁ and E ₂ , the rotational driving torque of the train 1 of flyweights M causes a double phenomenon of screwing between the piston 20 and the shafts 6, 8. This screwing then causes an axial displacement of the piston 20 until it comes into end-of-travel abutment against the bottom 15.

In this position, the weights M of the two weights trains 1, 2 rotate in phase opposition and their resulting moment is zero.

When pressurized fluid is injected into the working chamber E ₁ , this piston 20 is subjected to an axial force which tends to move it away from the bottom 15 and therefore to generate a relative double rotation between the two shafts 6, 8 and this, thanks to the combined action of the threads 17, 22 on the threads 12, 24. Of course, the latter are designed so as to cause a relative double rotation of the shafts 6, 8 which can reach 180 ° (reshaping weights M).

It is clear that this relative rotation only occurs insofar as the increment of engine torque resulting from the admission of the pressurized fluid into the chamber E ₁ becomes greater than the resistive torque that the object subjected to vibrations opposes to the vibrator (resistance to driving).

• un distributeur hydraulique D dont les deux sorties D₁, D₂ sont respectivement reliées, par l'intermédiaire de deux circuits hydrauliques respectifs C₁, C₂, aux entrées des deux joints tournants 27, 30 du déphaseur 7,
• un détecteur accélérométrique A associé à un conditionneur CA destiné à effectuer un traitement et une numérisation des informations accélérométriques délivrées par le détecteur A,
• un afficheur S apte à effectuer la saisie et l'affichage d'une valeur de consigne,
• un processeur PC pouvant consister en un automate programmable qui détermine l'écart entre les informations délivrées par le conditionneur et la valeur de consigne saisie dans l'afficheur S, et qui commande le distributeur D et donc le déphasage assuré par le déphaseur 7, de manière à annuler ledit écart.

According to the invention, the admission of the hydraulic fluid inside the chambers E ₁ , E ₂ is ensured by a servo control involving:

• a hydraulic distributor D, the two outputs D ₁ , D _{2 of which} are respectively connected, by means of two respective hydraulic circuits C ₁ , C ₂ , to the inputs of the two rotary joints 27, 30 of the phase shifter 7,
• an accelerometric detector A associated with a conditioner CA intended to carry out a processing and a digitization of the accelerometric information delivered by the detector A,
• a display S capable of entering and displaying a set value,
• a PC processor which may consist of a programmable automaton which determines the difference between the information delivered by the conditioner and the set value entered in the display S, and which controls the distributor D and therefore the phase shift provided by the phase shifter 7, so as to cancel said deviation.

Of course, the PC processor can be equipped with various peripherals common such as a CE keyboard / screen console, an I printer, etc.

As previously mentioned, the accelerometric detector A can be placed on the housing of the vibrator, its sensitive axis being parallel to the axis of propagation of vibrator vibrations. In this case, the AC conditioner performs a double integration of the sinusoidal signal emitted by the sensor accelerometer A, as well as an analog / digital conversion of this signal. The signal transmitted to the processor PC is then a signal representative of the amplitude of the vibrations generated by the vibrator.

The setpoint that the operator will have to display on the display S will therefore be a value representative of an amplitude of these driving vibrations. This value can be determined after an exploratory phase so that that it corresponds to a sufficient amplitude to ensure sinking but below a harmfulness threshold for neighboring sensitive installations.

Depending on the setpoint chosen, the PC processor controls the distributor D, generally a hydraulic slide, so as to adjust the rotation in one direction or the other of the phase shifter (which rotates at the speed of eccentric weights of the vibrator).

This device stands out from the possibility of manual controls currently available on variable time vibrators, generally imprecise and which, for the same result, would require manipulation constant by the operator as well as a passive reading of the amplitude for continuously adjust the amplitude to the desired value.

In addition, this solution makes it possible to alleviate the defects of rotary joints. used for the supply of hydraulic fluid to the phase shifter 7: these seals do not are not waterproof and are therefore fitted with drains. They only allow therefore not to keep, without regular and frequent corrections, a value of given phase shift.

Automation of the phase shift control eliminates all of these defaults. It also makes it possible to compensate for the variation in amplitude associated with variation in the types of soil crossed.

According to another variant of the invention, the accelerometric detector A can include one or more accelerometric sensors (for example a set of three sensors oriented along three orthogonal axes) placed on the structure which one wishes to protect against vibrations, so as to allow the measurement, in one or more directions, of the amplitude of the vibration at which is subject to this structure.

In an analogous manner, the accelerometric signal delivered by each of the detector accelerometers undergo a transformation in the AC conditioner and dual integration as well as analog / digital conversion. The signal present at the output of the AC conditioner, which is representative of the particle velocity of the soil is applied to an input of the PC processor. This one may process accelerometric information to deduce a value indicative of the harmfulness of the particulate velocity detected. This value could for example correspond at any time to the signal greatest accelerometer among the signals delivered by all the sensors accelerometer. Likewise, this processor can determine, depending on the parameters received, a harmfulness law as a function of the speed of the motors and / or the amplitude of the vibrations.

This value indicative of the harmfulness of the particle speed is compared by the processor PC to a value representative of a harmfulness threshold, determined and entered by the operator. The processor can then act, as a function of the above law, on the hydraulic distributor D with a view to increasing or reducing the amplitude of the vibrations emitted by the vibrator and / or on the speed variation control CV of the motors H ₁ and H ₂ to reduce the indicative value of the harmfulness to a value at most equal to the threshold harm value.

Given the distance, possibly large, between the vibrator and the location of the accelerometric detector A, the connection between, on the one hand, this detector possibly associated with the conditioner and secondly, the processor, may be effected by means of a transmission device distance such as cable or radio link.

In fact, we display here in the PC processor the acceleration value or the maximum particle speed allowed for the structure to be protected and programs the processor so that it controls the vibrator, no longer by compared to a setpoint value of the same kind but compared to the impact of the vibration measured on the installation itself which constitutes the target, by compared to the maximum value allowed for this target.

Of course, the device according to the invention can comprise several accelerometric detectors respectively installed at several facilities or targets. In this case, the processor will adjust the amplitude of the vibrator compared to the most restrictive of the targets to be protected.

Claims (9)

1. Device for retroactive control of the amplitude of the vibrations of a variable-moment vibrator can that be used to drive objects into the ground, this vibrator comprising at least two trains (1, 2) of eccentric feeders (M, M') each comprising at least two eccentric feeders (M, M') mounted rotatably about shafts integral with two respective pinions (P) meshing with one another so as to rotate in opposite directions to one another, under the effect of a motorization which can comprise one or more motors (H₁, H₂) a variation of the vibratory moment generated by the two trains (1, 2) of feeders (M, M') being obtained by means of a phase shifter (7) capable of generating a variable angular phase shift between the rotary motions of the two trains (1, 2) of feeders (M, M'),
      characterised in that it uses at least one accelerometric detector (A) positioned so as to be subjected to the vibrations generated by the vibrator, a means for deducing a value representing the harmfulness of the vibrations on the basis of the accelerometric data provided by the accelerometric detector (A), a means (S) for entering a set value, and an electronic processing means (P) associated with an actuating means (D) acting on the phase-shift control of the phase shifter (7) and/or the motorization speed variation control in order to maintain the value representing the harmfulness of the vibrations at a level equal to or lower than the set value.
2. Device as claimed in claim 1,
   characterised in that the set value results from on-site trials conducted beforehand.
3. Device as claimed as one of the claims 1 and 2,
   characterised in that the aforesaid electronic processing means are conceived in order to determinate on-site trials conducted beforehand, a harmfulness/amplitude law of the vibrations - vibrations frequency, said law being used by the device for the automatic control to set the vibrations amplitude and/or frequency in order to maintain the harmfulness of the vibrations at a level equal to or lower than the set value.
4. Device as claimed as one of the claims 1 and 2,
   characterised in that the accelerometric detector (A) comprises an accelerometer positioned on the vibrating housing of the vibrator.
5. Device as claimed as one of the claims claims 1 to 3,
   characterised in that the accelerometric detector (A) is installed on a structure to be protected.
6. Device as claimed in claim 5,
   characterised in that the transmission between the accelerometric detector (A) and the electronic processing means (P) is performed by any known remote transmission means such as a wire connection or radio link.
7. Device as claimed in claim 6,
   characterised in that the accelerometric detector (A) comprises three accelerometric sensors angles according to three orthogonal axes.
8. Device as claimed in claim 7,
   characterised in that, at all times, the electronic processing means takes into consideration the most important accelerometric signal of all the signals put out by the accelerometric sensors.
9. Device as claimed any one of claims 5 to 8,
   characterised in that which comprises plural accelerometric detectors (A) respectively installed on several installations or targets, with the electronic processing means then setting the amplitude and/or the frequency of the vibrator in relation to the most demanding of the targets to be protected.

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