EP1683754A1 - Loader with device for dampening boom bouncing - Google Patents

Abstract

The engine has an arm displaceable between a top position and lower position by a jack (3). The jack has a chamber (5) connected permanently with an active dampening device (11) and a chamber (4) connected with a distributor (6) through a safety valve (7) for supplying pressurized fluid to the chamber. The chamber (4) is connected with an accumulator (8) through a pipe (9) closable by a valve (10). The valve (10) is movable between two positions in which the valve stops and authorizes the passage of fluid towards the accumulator, respectively, in corresponding changing of the engine from a standard functioning mode towards an anti-pitching functioning mode.

Description

The present invention relates to a type of rolling machine equipped with an arm, such as a tool arm, movable between a high position and a low position by means of a cylinder whose chambers are each connected to a distributor adapted to supplying the first chamber of the cylinder with fluid under pressure and receiving from the second chamber, said shaft chamber, fluid under low pressure, to cause the output of the cylinder rod and consequently a displacement, such as lifting, of the arm of the machine, or to supply the chamber on the rod side, in pressurized fluid and to receive from the first fluid chamber under a variable pressure according to the load transported, to cause the retraction of the cylinder rod and consequently a displacement such as the lowering of the arm of the machine.

It relates more particularly to a rolling machine equipped with a jack whose first chamber, connected to the distributor with the interposition of a normally closed safety or balancing valve, is further connected to an accumulator via a pipe closable with a valve movable between a first position in which the valve prevents the passage of fluid to the accumulator and a second position in which the valve allows the passage of fluid to the accumulator, the displacement of the valve from the first to the second position occurring during the switching of the machine from a standard operating mode to an anti-pitching operating mode in which the shocks resulting from shaking or encounters of the machine with an obstacle are damped at the arm.

Many machines, in particular telescopic carriages, have a lift arm pivotally mounted on the rear part of the chassis of the machine, this arm extending with its tool in the lower position beyond the front part of the vehicle. machine. This arrangement of the arm, with respect to the chassis of the machine, requires, in particular in the transport position, that is to say when the arm is raised and supports a load, to dampen the movements of the arm to facilitate the driving of the machine by eliminating bounces and pitching in the arm, especially in case of encounter with an obstacle to limit the risk of accidents.

Telescopic carriages equipped with such an arm damping device, also called an anti-pitching device, are well known to those skilled in the art. Generally, such trolleys further comprise a safety valve which prevents an inadvertent descent of the arm in case of rupture of the hose between the arm lift control cylinder chamber and the cylinder feed distributor.

An example of such a machine is described in particular in EP-A-1,157,963. This document describes a telescopic loader-type machine whose lifting arm is controlled in displacement by a jack which, in anti-pitching mode, has one of its chambers connected by means of a valve to an accumulator and its another chamber connected by another valve to a zone of lower pressure to allow oscillation movement of the cylinder rod and consequently a damping of the arm. The disadvantage of this charger is that it is necessary, in the active state of anti-pitching mode, when controlling the descent of the lifting arm, to detect this descent to close the solenoid valve between the one of the cylinder's chambers and the lower pressure zone. These detection means generate a complexity of the assembly.

Other examples of machines equipped with a hydraulic damping device are in particular provided in patents FR-2,851,592, WO 98/17873, DE-10227966, WO 2004/104427 and DE-9208942 cited as examples. technological background of the invention.

An object of the present invention is therefore to provide a rolling machine of the aforementioned type whose anti-pitching design makes it possible to overcome the means detection of the descent of the lift arm in the activated state of the anti-pitching mode.

For this purpose, the subject of the invention is a rolling machine of the type equipped with an arm, such as a tool-carrying arm, movable between a high position and a low position by means of a jack whose chambers are connected to each other. each to a distributor adapted to supply the first chamber of the cylinder with fluid under pressure and to receive from the second chamber, said shaft chamber, fluid under low pressure, to cause the output of the cylinder rod and consequently a displacement, such as lifting, from the arm of the machine, or supplying the chamber on the rod side, with fluid under pressure and receiving from the first chamber of the fluid under a variable pressure depending on the load transported, to cause the retraction of the rod of a cylinder and consequently a movement, such as the lowering of the arm of the machine, the first chamber, connected to the distributor with the interposition of a normally closed safety or balancing valve, being further connected to an accumulate ur via a pipe closable with a valve movable between a first position in which the valve prohibits the passage of fluid to the accumulator and a second position in which the valve allows the passage of fluid to the accumulator, moving the valve from the first to the second position occurring during the switching of the machine from a standard operating mode to an anti-pitching operating mode in which the shocks resulting from shaking or encounters of the machine with an obstacle are damped at the arm, characterized in that the second chamber, or rod side chamber, the cylinder is permanently connected to an active damping device.

Thanks to the fact that the second chamber, or chamber rod side of the jack, is permanently connected to an active damping device, it is no longer necessary to detect the control of the descent of the lift arm, including in the operating mode. anti-pitching operation of the machine. The result is a simplicity of construction.

According to a preferred embodiment of the invention, the second chamber is connected to a tank by a calibrated passage allowing a permanent leakage rate of said second chamber.

• la figure 1 représente une vue schématique du circuit hydraulique du vérin dans un mode de fonctionnement standard de l'engin, la sortie de tige du vérin étant commandée ;
• la figure 2 représente une vue schématique d'un circuit hydraulique du vérin de l'engin en mode de fonctionnement standard de ce dernier, la rentrée de tige du vérin, correspondant à une descente du bras de levage, ayant été commandée ;
• la figure 3 représente une vue schématique du circuit hydraulique du vérin du bras de levage de l'engin en mode de fonctionnement anti-tangage ;
• la figure 4 représente une vue schématique du circuit hydraulique du vérin équipant le bras de levage de l'engin en mode de fonctionnement anti-tangage de l'engin lors de l'absorption d'un choc provoquant une rentrée de la tige du vérin ;
• la figure 5 représente une vue schématique du circuit hydraulique du vérin du bras de levage de l'engin en mode de fonctionnement anti-tangage de l'engin lors d'une sortie de la tige du vérin correspondant à une restitution d'énergie suite à un choc ;
• la figure 6 représente, sous forme schématique, un circuit hydraulique du vérin du bras de levage de l'engin en mode de fonctionnement anti-tangage de l'engin lors de la commande de la sortie de tige du vérin correspondant au levage du bras et
• la figure 7 représente une vue schématique du circuit hydraulique du vérin du bras de levage de l'engin en mode de fonctionnement anti-tangage de l'engin lors de la commande de la rentrée de tige du vérin correspondant à une descente du bras de levage.
• la figure 8 représente une vue schématique d'un engin roulant muni d'un bras de levage, selon l'invention.

The invention will be better understood on reading the following description of exemplary embodiments, with reference to the appended drawings in which:

• FIG. 1 represents a schematic view of the hydraulic circuit of the jack in a standard operating mode of the machine, the rod output of the jack being controlled;
• Figure 2 shows a schematic view of a hydraulic system of the cylinder of the machine in the standard operating mode of the latter, the retraction of the rod of the cylinder, corresponding to a descent of the lifting arm, having been controlled;
• Figure 3 shows a schematic view of the hydraulic circuit of the jack of the lifting arm of the machine in anti-pitching operation mode;
• FIG. 4 represents a schematic view of the hydraulic circuit of the jack equipping the lifting arm of the machine in anti-pitching operation mode of the machine during the absorption of an impact causing a retraction of the rod of the jack;
• FIG. 5 represents a schematic view of the hydraulic circuit of the jack of the lifting arm of the machine in anti-pitching operation mode of the machine during an output of the rod of the jack corresponding to a restitution of energy following a shock ;
• FIG. 6 represents, in schematic form, a hydraulic circuit of the cylinder of the lifting arm of the machine in anti-pitching operation mode. of the machine when controlling the rod output of the cylinder corresponding to the lifting of the arm and
• FIG. 7 represents a schematic view of the hydraulic circuit of the jack of the lifting arm of the machine in anti-pitching operation mode of the machine when controlling the retraction of the rod of the jack corresponding to a descent of the lifting arm. .
• Figure 8 shows a schematic view of a rolling machine provided with a lifting arm, according to the invention.

As mentioned above, the rolling machine 1, object of the invention consists of a rolling frame equipped with a 2-tool holder arm. The chassis is thus provided with wheels generally front and rear for its movement. This frame has, at its rear part, a pivot axis for receiving a 2-arm tool holder. This arm is thus pivotally mounted on the frame to be able to move from a low position to a high position and vice versa. This passage from one position to another is obtained by means of a jack 3 which extends between the arm 2 and the chassis of the machine. Thus, in the low position, the arm, which may optionally be telescopic and which is provided at its free end with a tool, such as a handling tool, extends beyond the front portion of the frame. As it moves from a low position to a high position, it pivots about its hinge axis to the chassis to move from the front to the rear of the chassis. The double-acting jack 3 allowing the movement of the tool-holder arm 2 between a high position and a low position consists of a generally cylindrical body housing a piston 3B equipped with a rod 3A. The rod 3A of the piston is generally connected at its free end by a pivot connection to the lifting arm 2 while the cylinder body is likewise connected by a pivot connection to the frame of the machine. The piston 3B allows the delimitation inside the cylinder 3 of two chambers shown at 4 and 5 in the figures. Each of the chambers is connected to a distributor 6 whose hydraulic source is represented by a circle / point assembly while the reservoir is represented by an open U. The distributor 6 allows, by via a connecting pipe 20, supplying the first chamber 4 of the cylinder 3 with fluid under pressure and receiving, via a connecting pipe 17, the second chamber 5, said chamber side 3A rod, fluid under low pressure to cause the output of the rod 3A of the cylinder 3 and therefore a displacement such as the lever arm 2 of the machine. Similarly, when the chamber 5, shaft side 3A, is supplied with pressurized fluid by the distributor 6, and that it receives from the first chamber 4 of the fluid a variable pressure depending on the load transported, it is then caused to return the the rod 3A of the cylinder and consequently a displacement, such as the lowering, of the arm 2 of the machine 1.

The first chamber 4 is connected to the distributor 6 with the interposition of a normally closed safety or balancing valve 7. This first chamber 4 is furthermore connected to an accumulator 8 via a pipe 9 which can be closed by means of a valve 10. This valve 10, such as a solenoid valve, is movable between a first position in which the valve 10 prevents the passage of fluid to the accumulator 8 and a second position in which the valve 10 allows the passage of the fluid to the accumulator 8. The displacement of the valve 10 from the first to the second position occurs during switching the machine from a standard operating mode to an anti-pitching operating mode in which shocks resulting from shaking or encounters of the machine with an obstacle are damped at the arm 2.

The second chamber 5, or rod side chamber 3A, of the cylinder 3 is in turn permanently connected to an active damping device 11. In the examples shown, this damping device 11 of the second chamber 5 consists of an oleopneumatic accumulator positioned on a bypass 12 of the connecting pipe 17 between second chamber 5 and distributor 6. This branch 12 is connected to a reservoir 16 by a calibrated passage 13, such as a nozzle, allowing a permanent leakage flow of said second chamber. This calibrated passage 13 is sized to allow the maintenance on the connecting line of the second chamber 5 to the distributor 6 a sufficiently high pressure capable of constituting the piloting pressure of the safety valve 7 or balancing during the descent control of the arm 2.

It is also planned, parallel to the calibrated passage 13, a pipe 14 provided with a non-return valve 15 allowing fluid circulation from the reservoir 16 to the second chamber 5 in order to avoid cavitation phenomena in said chamber 5 Finally, there is provided, on the bypass 12 of the connection duct between the second chamber 5 and the distributor 6, before the damping device 11, a calibrated passage 18, such as a nozzle, mounted in parallel with a flap 19 anti-return allowing the flow of fluid from the second chamber 5 to the damping device 11.

Other embodiments of the connection of the second chamber 5 to a tank 16 by a calibrated passage 13 allowing a permanent leakage rate of said chamber 5 can be envisaged without departing from the scope of the invention.

It must firstly be noted that the calibrated passage 13 and the associated reservoir 16 may be arranged either on a branch of a branch 12 of the line 17 connecting second chamber 5 and distributor 6, or on line 17 of FIG. link, or again at the distributor 6. The passage 13 calibrated can therefore, in view of these different configurations, be constituted indifferently of a nozzle, a fixed or adjustable flow regulator or an increase in clearance between bore and drawer of the distributor 6.

Equivalently, the non-return valve 15 acting as a pressure valve by allowing the fluid flow from the reservoir 16 to the second chamber 5 to prevent cavitation phenomena in the second chamber 5 can be mounted directly at the distributor level 6.

The machine is still equipped with switching means from the standard operating mode to the anti-pitching operating mode. These switching means of the machine are constituted for example by a contactor (not shown) which detects the low position of the arm or by a pressure switch, housed in the first chamber 4 of the jack and which detects a position in support of the arm 2. The detection of this position in support of the arm avoids a arm and load drop due to inflation of the accumulator 8 when going into anti-pitching mode.

The operation of such a machine is as follows. In idle anti-pitching mode, to allow lifting of the arm corresponding to the rod outlet of the cylinder, it is sufficient, in conventional manner, to supply, with the aid of the distributor 6, the first chamber 4 of the fluid cylinder under pressure while the second chamber 5 of the cylinder or rod side chamber 3A of the jack is connected to the distributor tank 6. In this operating mode, the valve 10 positioned on the circuit between the first chamber 4 of the jack and accumulator 8 is closed to prohibit any passage of the fluid to the accumulator 8. The safety or equalizing valve 7, positioned on the circuit between the first chamber 4 of the cylinder and distributor, is itself also closed. It should be remembered that this safety or equalizing valve 7 is intended to prevent any unintentional descent of the lifting arm, in particular when the hose is broken between the valve side 7B and the distributor 6. 7A side of the valve which connects the valve to the first chamber 4 of the cylinder is made by means of a rigid pipe preventing any risk of damage to this pipe. As mentioned above, this safety or equalizing valve 7 passes from a closed position to an open position when the pressure that prevails on the connecting line of the second chamber 5 of the jack to the distributor 6 reaches a value sufficient to open said valve. During the supply of the chamber 4 bottom side of the cylinder, the oil passes through the valve 7C mounted in parallel with the safety valve 7 or balancing and the safety valve 7 or balancing is closed. During the emptying of the chamber 5 rod side of the cylinder, a small portion of the oil volume is discharged through the nozzle 13 to the tank 16. A surplus of oil can also come to inflate the oleopneumatic accumulator shown in 11 on the derivation 12.

When controlling the descent of the arm 2 corresponding to the retraction of the rod 3A of the cylinder 3 in inactive anti-pitching mode, as illustrated in FIG. 2, the chamber 5 is supplied via the distributor 6. 3A rod side of the cylinder while the chamber 4 or first chamber of the cylinder is connected to the distributor tank 6. The pilot pressure on the connecting line between the distributor 6 and chamber 5 rod side of the cylinder leads to the opening of the 7 safety valve or balancing to allow the emptying of the chamber 4. The connection between chamber 4 and damping device 8 is kept closed. Part of the oil used to feed the cylinder-side chamber 5 of the cylinder is discharged through the bypass 12. Part of this surplus is discharged through the nozzle 13 while another part of the surplus oil inflates the oleopneumatic accumulator 11.

When the anti-pitching mode is activated, this anti-pitching mode being mainly used in transport with an average load of 1.5 tonnes and a lifting arm height to facilitate the driving of the machine, it results in the opening the solenoid valve shown in 10 to the figures so as to allow the direct connection of the first chamber 4 of the cylinder with the damping device consisting of the oleopneumatic accumulator 8. This opening of the connection between the first chamber 4 of the cylinder and the accumulator 8 allows a re-entry rod and a rod outlet when the encounter of the machine with any obstacle. Indeed, in order for the anti-pitching system to be effective, it is necessary, in a first step, for the shock to be received by the accumulator 8 so as to allow the rod to then return from approximately 20 to 25 mm, then in a second step, the energy recovery takes place, the stem emerging beyond its original position of about 15 to 20 mm. The cylinder rod oscillates several times until it returns to its original position. The re-entry of the rod is thus obtained by pressurizing the accumulator 8. In contrast, during this rod retraction movement, the cylinder-side chamber 5 of the cylinder is filled by depression via the reservoir 16 on the cylinder. which are positioned on the one hand the nozzle 13, on the other hand a non-return valve 15. This supply of the chamber 5 rod side 3A of the cylinder prevents any cavitation phenomenon. Indeed, as soon as the depression the second chamber 5 of the cylinder is greater than 0.05 bar, the contents of the tank 16 is sucked through the non-return valve 15 called pressure valve. This aspiration is done systematically without any electrical control.

In the energy recovery phase following the shock, the rod of the cylinder comes out. The energy return is obtained by the accumulator 8, the piston out to allow a supply of the first chamber 4 of the cylinder. The chamber 5 side rod 3A of the cylinder is drained as for it and comes, during this emptying, feed on the one hand the tank 16 through the calibrated passage 13, on the other hand the secondary accumulator 11 which cashes the excess flow due to the output of the rod 3A of the cylinder. The accumulators 8, 11 are chosen to withstand very high pressure ratios between the oil and the nitrogen. The accumulator 8 will preferably be piston to avoid the risk of bursting membrane or bladder that may exist for other types of oleopneumatic accumulators. The pressure rises under the effect of the oil circuit that inflates the oleopneumatic accumulator 11 and this pressure rises much more slowly until the movement reverses. The damping is slightly degraded because the more the rod comes out, the more the chamber side pressure 5 of the jack increases. In parallel, the higher the pressure, the more the nozzle 13 discharges oil.

When this anti-pitch mode is active and an arm lift corresponding to a cylinder rod output as shown in FIG. 6 is controlled, the same fluid displacements are observed as those obtained when the anti-pitching mode is inactive except that the connection between the first chamber 4 of the cylinder and the accumulator 8 is kept open. The accumulator 8 is therefore at the same pressure as the first chamber 4 of the jack. In this active anti-pitching mode, when a lowering of arms corresponding to a re-entry of a rod is controlled, the movements of oil are in conformity with those observed when the anti-pitching mode is inactive. It is observed again an inflation of the secondary accumulator shown at 11 to the figures and placed on a branch of the connection between the second chamber 5 of the cylinder and distributor 6. Again, the safety valve 7 or balancing is controlled in opening by the pressure on the connecting line between distributor 6 and second chamber 5 of the cylinder. Note that for the control of this downward movement of the arm, it is useless to detect the movements of distributor 6 or to cut the power supply of a solenoid valve. When the operator controls a descent movement via the distributor 6, only a small portion of the flow intended to supply the chamber on the rod side of the cylinder is discharged through the nozzle 13. The remainder of the flow feeds the second chamber 5 of the cylinder. It can thus be seen in the embodiments described that the chamber 5, on the rod side of the jack, is subjected to a permanent leak due to the presence of the nozzle 13 and the tank 16. This results in the suppression of the means necessary for the detection of the descent control of the arm.

Claims (9)

Machine (1) of the type equipped with an arm (2), such as a tool arm, movable between a high position and a low position by means of a jack (3) whose chambers (4, 5 ) are each connected to a distributor (6) able to supply the first chamber (4) of the cylinder (3) with fluid under pressure and to receive from the second chamber (5), called the rod-side chamber (3A), the fluid under low pressure, to cause the output of the rod (3A) cylinder (3) and consequently a displacement, such as lifting, the arm (2) of the machine, or to supply the chamber (5) rod side ( 3A), in fluid under pressure and to receive from the first chamber (4) of the fluid under a variable pressure according to the load transported, to cause the retraction of the rod (3A) of cylinder (3) and consequently a displacement, such as that the lowering of the arm (2) of the machine (1), the first chamber (4), connected to the distributor (6) with the interposition of a valve (7) safety or balancing normally fe rmée, being further connected to an accumulator (8) via a pipe (9) closable with a valve (10) movable between a first position in which the valve (10) prohibits the passage fluid to the accumulator (8) and a second position in which the valve (10) allows the passage of fluid to the accumulator (8), the displacement of the valve (10) from the first to the second position s' operating during the switching of the machine from a standard operating mode to an anti-pitching operating mode in which shocks resulting from shaking or encounters of the machine with an obstacle are damped at the arm (2) ,
characterized in that the second chamber (5), or rod-side chamber (3A), of the cylinder (3) is permanently connected to an active damping device (11). Rolling machine according to claim 1,
characterized in that the damping device (11) of the second chamber (5) consists of an oleopneumatic accumulator positioned on a branch (12) of the pipe (17) connecting the second chamber (5) and the distributor ( 6). Rolling machine according to claim 2,
characterized in that a calibrated passage (18) is provided on the branch (12) of the connection duct between the second chamber (5) and the distributor (6) before the damping device (11). a nozzle, mounted in parallel with a non-return valve (19) allowing the flow of fluid from the second chamber (5) to the damping device (11). Rolling machine according to one of claims 1 and 2,
characterized in that the second chamber (5) is connected to a tank (16) by a calibrated passage (13) allowing a permanent leakage flow of said second chamber (5). Rolling machine according to claim 4,
characterized in that the reservoir (16) is positioned on a branch of a branch (12) of the connecting duct (17) between the second chamber (5) and the distributor (6). Rolling machine according to one of claims 4 and 5,
characterized in that the passage (13) is calibrated indifferently by a nozzle, a fixed or adjustable flow regulator or an increase in clearance between bore and drawer of the distributor (6). Rolling machine according to one of Claims 4 to 6,
characterized in that the calibrated passage (13) is dimensioned to allow the maintenance, on the connecting line of the second chamber (5) to the distributor (6), of a sufficiently high pressure capable of constituting the driving pressure of the safety or balancing valve (7) when controlling the descent of the arm (2). Rolling machine according to one of Claims 4 to 7,
characterized in that a pipe (14) provided with a non-return valve (15) allowing fluid circulation is provided in parallel with the calibrated passage (13). from the reservoir (16) to the second chamber (5) in order to avoid cavitation phenomena in said chamber (5). Rolling machine according to claim 1,
characterized in that the switching means of the machine from the standard operating mode to the anti-pitching operating mode are constituted by a switch which detects the low position of the arm or a pressure switch which detects a position in support of the arm (2 ) of the machine.

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