EP0787235B1 - Earthmoving machine - Google Patents

Description

Technical area

The invention relates to a public works vehicle in particular of loader-excavator type, including articulated work equipment, more precisely a device allowing the control of an arm complex with a reduced number of manipulators, according to the preamble of claim 1.

Prior art

In a known manner, in particular as taught in the document FR-A-2,532,671 corresponding to American patent US 5,195,863, the excavator loaders have work equipment installed on a chassis. This work equipment consists of four parts hinged together, namely an arrow articulated by relation to the chassis by the boom cylinder, a boom spout articulated by relation to the boom by a boom spout cylinder, an arm articulated by relation to the arrow spout by an arm jack and finally a bucket or tool articulated with respect to the arm thanks to a bucket cylinder. So, such four-cylinder system, has a number of degrees of freedom four. To this is added an additional movement made up by the rotation of the turret relative to the chassis.

Generally, the driving of such devices is carried out by means two manipulators installed in the turret. These manipulators, movable longitudinally and transversely, therefore allow the control of four degrees of freedom. It therefore follows that with this mode of conventional driving, the use of work equipment improved as described above, requires adjustments.

To control the five degrees of freedom using the four directions manipulators, it was considered to install on one of the manipulators a contactor allowing, depending on the request of said contactor, to assign to the manipulator the control of two cylinders separate. This solution allows access to all the degrees of freedom of the machine, but is not satisfactory because it is notoriously distinguished from conventional driving modes, which can disturb operators using various types of gear.

It was also envisaged to ensure the control of one of the cylinders by a pedal, but this solution has the same disadvantages than the previous one.

The problem which the invention proposes to solve is to allow driving a public works machine including work equipment has more degrees of freedom than control manipulators to available to the driver, in the same way as a machine simple conventional, while retaining the possibility of achieving with the tool, the multiplicity of positions that an equipment can reach complex work.

JP A 61 028632 describes a mechanical shovel, the work equipment has two arms at the end of which is mounted a bucket. To allow horizontal erasure, it is planned to provide this machine with means for simultaneously controlling with a single manipulator, the two cylinders determining the orientation of the arms. Unfortunately, this solution does not resolve the problem posed, because on the one hand, the number of manipulators available is equal to the number of cylinders, and on the other hand, it absolutely impossible thanks to the system described to bring the bucket to a level different from that of the ground.

The invention aims to overcome these drawbacks.

Description of the invention

The invention aims to make compatible with an order conventional, piloting complex work equipment, with more degrees of freedom than manipulator positions accessible.

• un équipement de travail composé de quatre éléments articulés et angulairement déployables les uns par rapport aux autres, le premier étant articulé par rapport au châssis, le dernier étant constitué par un outil,
• des moyens permettant de commander le déplacement angulaire desdits éléments les uns par rapport aux autres, lesdits moyens comprenant:
• a) des vérins hydrauliques, aptes à modifier le positionnement angulaire entre deux éléments consécutifs, l'alimentation en fluide de chaque vérin étant assurée par un distributeur,
• b)des manipulateurs délivrant un ordre de commande actionnant les distributeurs,

caractérisé par les caractéristiques de la partie caractérisante de la revendication 1. The invention relates to a public works machine comprising:

• work equipment composed of four articulated and angularly deployable elements relative to each other, the first being articulated with respect to the chassis, the last being constituted by a tool,
• means making it possible to control the angular displacement of said elements with respect to each other, said means comprising:
• a) hydraulic cylinders, capable of modifying the angular positioning between two consecutive elements, the supply of fluid to each cylinder being ensured by a distributor,
• b) manipulators issuing a control order actuating the distributors,

characterized by the features of the characterizing part of claim 1.

In other words, for a machine comprising a number of cylinders to order greater than the number of positions accessible by control station manipulators, the invention consists in supplying two cylinders simultaneously, so that the operator actuates these two cylinders in a single operation with a single manipulator. In others terms, we couple two of the cylinders to reduce the number of degrees of freedom of work equipment and make it equal to the number of positions accessible by the manipulators.

Advantageously, in practice, the simultaneous actuation of the two coupled cylinders is ensured by a circuit comprising valves putting in relation to the distributor control circuit of one of the cylinders with the distributor control circuit of the other cylinder.

In the following description, the order of order is a pressure but the invention also covers control systems electric.

In a particular embodiment, more particularly adapted to the excavator function, the flow rates of the distributors corresponding to the coupled cylinders, are adjusted so that the full stroke times of the two coupled cylinders are equal.

In other words, in this embodiment, the cylinders coupled at the same time, from the maximum folded position to the maximum deployment position, and vice versa.

In another embodiment, more particularly advantageous for shippers, the flow rates of the corresponding distributors coupled cylinders are adjusted to maintain the horizontality of the tool.

In a more sophisticated embodiment, one of the two coupled cylinders is supplied by its distributor which is controlled directly by the manipulator, and the control pressure of the distributor of the other cylinder is developed by a device control according to the angles corresponding to the two cylinders.

• deux capteurs de position angulaire déterminant les valeurs d'angle correspondant aux vérins couplés ;
• un boitier calculateur élaborant un courant en fonction de la différence pondérée des valeurs issues des capteurs ;
• deux électrovannes modérables commandées par ledit courant, et délivrant une pression de commande au distributeur d'alimentation du vérin, chaque électrovanne commandant le déplacement du vérin dans un sens.

In this embodiment, the servo device advantageously comprises:

• two angular position sensors determining the angle values corresponding to the coupled cylinders;
• a computer box developing a current as a function of the weighted difference of the values from the sensors;
• two moderated solenoid valves controlled by said current, and delivering a control pressure to the actuator supply distributor, each solenoid valve controlling the displacement of the actuator in one direction.

This form of control by a regulating device allows get rid of leaks and drifts by adjusting the flow rates of the distributors.

In the case of a machine comprising a work equipment in four elements, namely an arrow, a spout boom, arm and bucket, this machine being used as an excavator, we observe that the best results are obtained for a coupling of cylinders respectively connecting the boom with the boom spout and the spout arrow with arm. Likewise, the same machine used in a loader gives more particularly satisfaction when the coupling associates the jacks connecting the boom spout with the arm and the arm with the bucket, respectively.

Brief description of the figures

The manner in which the invention can be realized and the advantages which will result, will emerge better from the example of embodiment which follows to using the attached figures.

Figure 1 is an overview of a machine highlighting the different elements of work equipment.

Figure 2 is a hydraulic control diagram of the equipment according to the invention.

Figure 3 is a hydraulic control diagram incorporating a servo device.

Figure 4 is a diagram showing the envelope of positions accessible by the tool, with and without coupling of the cylinders.

Figure 5 is an overview of a machine used as charger.

Way of realizing the invention

The invention described is applied to a loader / excavator machine classic (Figure 1) or as a charger (Figure 5).

Such a machine as shown in Figure 1, carried a work (1) in four elements: an arrow (2), an arrow spout (3), an arm (4) and a bucket (5).

The boom (2) is articulated relative to the turret (6) and its position is adjusted by the boom cylinder (7) by means of two arms (8,9). The beak of arrow (3) is connected to the other end (10) of the arrow (2) and the position angular α of these two elements (2,3) is adjusted by means of the jack (11) of arrowhead. Similarly, the arm (4) is connected to the other end (12) of the arrow spout (3) and the corresponding angle β is a function of the position of the arm cylinder (13). Finally, the bucket (5) is hooked to the end (14) of the arm (4) and its position is adjusted by the bucket cylinder (15).

The diagram in Figure 2 illustrates the most preferred embodiment. simple that makes it easy to understand how are ordered the different cylinders (11,13), to ensure a operating in a conventional manner, each cylinder being controlled by a manipulator, i.e. operation in accordance to the invention where a single manipulator makes it possible to control two cylinders simultaneously.

In this embodiment, each cylinder (11,13) is associated with a distributor (30,31). This distributor (30,31) is used to supply the room elongation (32,33) and the withdrawal chamber (34,35) of the jack (11,13). All the distributors (30,31) are supplied by a variable flow pump (36) driven by the engine of the machine. This pump (36) supplies also a pressure reduction block (40) which delivers pressure (41) to the manipulators 42,43). These manipulators (42,43), depending on their position, deliver this pressure (41) to the different distributors (30,31) with which they are associated. The opposite positions of each manipulator (42,43) generates opposite movements of the cylinders (11,13) to which they relate.

In FIG. 2, it can be seen that the control circuit of the second distributor (31) can be supplied either by the associated manipulator (43), either by the first manipulator (42).

This alternative depends on the position of the valves (45,46).

In the "uncoupled" position, as shown, the manipulator (42) controls the distributor (30) which supplies the jack (11) and the manipulator (43) controls the distributor (31) which supplies the cylinder (13).

In the "coupled" position, the valves (45,46) set communication, thanks to branches (47,48), ks control circuits (37) of the distributor (30) of the first cylinder (11) with the circuit of control (38) of the distributor (31) of the second cylinder (13). The manipulator (42) feeds the distributor (30) as well as the distributor (31). The manipulator (43) is therefore available for controlling a other organ. In this coupled position, the two distributors (30) and (31) being controlled by the same pressure, the adjustment of the flow rates is obtained by the proportional effect of the dispenser drawers.

Advantageously, we choose to adjust the flow rates of the distributors (30,31) so that the cylinders (11,13) have the same times of full stroke. This implies that when the two cylinders (11,13) depart from an extreme position, they reach the opposite extreme position at the same time.

This fully hydraulic control principle allows for drift from one cylinder to the other over time, which can be corrected by operator action by bringing the two cylinders back to the bottom of racing, these reaching their mechanical stop. This operation happens naturally when using the shovel on large deflections.

In the alternative embodiment illustrated in FIG. 3, in the position coupled, the control of the second cylinder (13) is done by a device regulation to correct any drifts observed in a purely hydraulic device. In this particular form, the the most loaded cylinder, that is to say providing the most effort, is conventionally controlled by a manipulator (42) and a distributor (30). However, the second cylinder (13) is controlled by a servo device consisting of two potentiometers (50,51) determining the angles (α, β) corresponding to the jacks (11), a housing computer (52) supplying two moderatable solenoid valves (53,54), which solenoid valves (53,54) control the distributor (31) of the second cylinder (13), the actions of the two solenoid valves being opposite. The stroke time of the two cylinders (11,13) being equal, this translates geometrically by a relation between the angles α and β. That relation is saved in the computer unit (52). It is therefore suitable for compare the angle β observed with the theoretical value recorded. In function of this difference and its sign, the computer unit determines a current (56) to be applied to one or the other solenoid valve (53,54) which delivers a pressure (55,57) for controlling the distributor (31).

So we are dealing with a real slave system in which the two cylinders (11,13) scrupulously follow the control law optimal determined to give maximum excursion to the tool.

This excursion is represented in figure 4, and materializes one of the key points of the invention. This diagram shows in solid lines (70) the envelope of all the points accessible by the tool (5) when the four cylinders (7,11,13,15) are actuated independently. In other words, the interior of this outline represents the useful workspace. We observe at inside this curve a second curve (71) in dotted lines which also represents the envelope of accessible points, but in the case where two of the cylinders are coupled. The cylinders chosen in this coupling specific are the boom cylinder (11) and the arm cylinder (13), and the comparative observation of the two curves (70,71) shows that the decrease in a degree of freedom only results in a decrease limited workspace. Obviously, one of the objects essential of the invention is to determine which of the four cylinders (7,11,13,15) must be coupled to obtain a working space acceptable.

As we saw earlier, in the case of a shovel or excavator, optimal coupling is obtained by coupling the spout cylinders boom (11) and arm (13).

However, in the case of a loader illustrated in FIG. 5, the use of the cylinders is different. In this case, the arrow (2) takes a fixed position all the time of the operation, i.e. inclined as far back as possible, folded over the turret (6). The operations of loading takes place by the movement of the boom spout (3) of the arm (4) and of the bucket (5). The best results have been obtained by coupling the cylinder arm (13) and the bucket cylinder (15), this to maintain the horizontality of the bucket. In this specific case, the jacks (13,15) respect a law of movement different from that already observed, that is to say that their course does not operate at the same time, but follows a law that keeps constant the angle of the bucket with the horizontal. The same way as previously, the flow rates of the corresponding distributors are adapted and calculated to obtain this result. In this way, the order by a single manipulator, allows to maintain the horizontality of the bucket without having to make manual corrections such as current systems oblige him.

It appears from the above description that the excavator loaders according to the invention have certain advantages.

On the one hand, they allow the use of work equipment complex with a multitude of degrees of freedom, while being compatible with traditional operator stations for two dual control manipulators. On the other hand, they simplify clearly driving advanced machinery while ensuring automatically relative positioning of cylinders, thereby eliminating delicate manual operations, while retaining the possibility of individual control of each cylinder.

Claims (6)

1. A civil engineering works machine including :

   working equipment (1) composed of at least four elements (2, 3, 4, 5) which are articulated and can be deployed angularly with respect to each other, the first (2) being articulated with respect to the chassis (6), the last (5) consisting of a tool,

   means making it possible to control the angular displacement of said elements (2, 3, 4, 5) with respect to each other, said means comprising :

   a) hydraulic rams (7, 11, 13, 15) capable of altering the angular position between two consecutive elements, the fluid supply to each ram (7, 11, 13, 15) being provided by a distributor (30, 31),

   b) manipulators (42, 43) delivering a command actuating the distributors (30, 31),

   wherein it includes means (45, 46) for coupling the commands of the distributors :

   either for the two of the rams (11, 13) respectively linking the boom (2) with the boom tip (3), and the boom tip (3) with the stick (4) ;

   either for the two of the rams (13, 15) respectively linking the boom tip (3) with the stick (4) and the stick (4) with the tool (5),

   said coupling means making it possible to actuate these two rams simultaneously using the command from just one manipulator, so as to position the tool at any point lying inside a contour of a given work space.
2. The civil engineering works machine as claimed in claim 1, wherein the coupling means consist of a circuit (47, 48) comprising valves (45, 46) placing the control circuit of the distributor (30) of one of the rams (11) in communication with the control circuit of the distributor (31) of the other ram (13).
3. The civil engineering works machine as claimed in claim 1, wherein the throughputs of the distributors (30, 31) corresponding to the coupled rams (11, 13) are set so that the full stroke times of the two coupled rams (11, 13) are equal.
4. The civil engineering works machine as claimed in one of claims 1 and 2, wherein the throughputs of the distributors (30, 31) are set to keep the tool (5) horizontal.
5. The civil engineering works machine as claimed in claim 1, wherein the coupling means consist of an automatic-control assembly (59) formulating the command (55) for the distributor (31) of one of the rams (13) as a function of the angles (α, β) corresponding to the two rams (11,13).
6. The civil engineering works machine as claimed in claim 5, wherein the automatic-control assembly comprises :

   two angular-position sensors (50, 51) determining the magnitudes of the angle (α, β) corresponding to the coupled rams (11, 13) ;

   a computation unit (52) formulating a current (56) as a function of the weighted difference in the values from the sensors (50, 51) ;

   two adjustable solenoid valves (53, 54) controlled by said current (56) and delivering a control pressure (55) to the distributor (31) feeding the ram (13), each solenoid valve (53, 54) controlling the displacement of the ram in one direction.

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