EP1370731B1 - Loader-type heavy-construction machine - Google Patents

Abstract

A loader-type heavy construction machine has a chassis and work equipment. The work equipment includes two parallel arms articulated relative to the frame, a bucket articulated relative to the arms, a set of link rods forming, with a portion of the bucket and of the arms, a deformable parallelogram, and a bucket actuator capable of being controlled to cause deformation of the deformable parallelogram so as to orient the bucket with respect to the arms. A cam is moved by a connecting bar connected at one end to the deformable parallelogram so that the position of the cam is dependent on the orientation of the bucket with respect to the chassis. The cam interfaces with an hydraulic circuit to ensure that the bucket is maintained in a position preventing it from accidentally tipping over backwards, regardless of commands exerted on an hydraulic manipulator by a driver of the machine.

Description

Technical area

The invention relates to the field of public works machinery, and more particularly with loaders. More specifically, it targets device ensuring automatic correction of the bucket orientation during different loading operations.

Previous techniques

Generally speaking, a "loader" is a public works machine which allows materials taken up from the ground to be taken up and dumped into a grab or in a truck, or vice versa. A loader therefore understands so. known a chassis and special work equipment. This equipment work typically includes two parallel arms that are hinged relative to the frame. These arms can be lifted under the action of jacks generally called "arm cylinders".

The ends of the arms receive a bucket, which is itself articulated by compared to the arms. To ensure the movement of the bucket relative to the arms, the work equipment also includes a set of rods which form with a portion of the bucket and the arms, a deformable parallelogram. In a way general, one of these links is articulated relative to the bucket, while the other is articulated relative to the arms, these two links being articulated to each other by their ends. Work equipment also includes a bucket cylinder which is controlled to cause the deformation of the deformable parallelogram, which ensures the orientation of the bucket relative to the arms.

Driver can control arm cylinder and cylinder separately of bucket. Thus, by acting on the arm jack, it raises the arms by raising the bucket level

By acting on the bucket cylinder, it changes the orientation of the bucket relative arms, and therefore relative to the chassis. So after the bucket has been filled with materials, it is pivoted backwards so that its opening is facing up. Conversely, when the bucket has reached the desired height, it is pivoted forwards, so as to be emptied inside the grab destination.

As the bucket is placed at the end of the main arms, when these the latter are raised, the orientation of the bucket varies relative to the ground. To avoid so that the bucket does not pour backwards, it is necessary that the orientation of the bucket relative to the arms is modified by the deformation of the parallelogram deformable. During the raising movement of the arms, the bucket cylinder is therefore actuated to maintain the opening of the bucket in a constant inclination, to prevent it from spilling backwards unexpectedly.

This bucket tilt correction can be performed by the operator which acts appropriately on the bucket cylinder through the manipulator.

This bucket tilt correction can also take place automatic by a correction device. Such a device includes so known a connecting rod which is articulated at one of these ends on one of the deformable parallelogram links. At its other end, the connecting rod acts on a hydraulic distributor drawer supplying the bucket cylinder. This rod linkage actuates the distributor drawer which acts on the bucket cylinder depending on the position of the connecting rod, i.e. depending on the orientation of the bucket relative to the arms.

It is understood that this solution has certain drawbacks and in particular the it acts directly on the dispenser drawer, which results in a reaction of the control manipulator on which the driver acts.

In other words, this automatic correction generates resistance in the movement of the manipulator which is felt by the driver and which can be unpleasant.

In addition, such a correction by mechanical action on the dispenser hydraulic is incompatible with the use of a hydraulic manipulator, which acts on the distributor by applying a pressure depending on the position of the manipulator.

Solutions have already been proposed consisting in equipping the arms and the deformable parallelogram with additional sets of connecting rods connected to the both on the chassis and on the rods, so as to cause the deformation of the deformable parallelogram, and therefore correcting the orientation of the bucket function of arm movement. Such a solution is mechanically complex, and its adjustment is particularly difficult.

A public works machine according to the preamble of claim 1 is disclosed in US-A-5,501,570.

A first problem which the invention proposes to solve is that of allow a correction of the inclination of the bucket, without the latter being felt at the level of the manipulator. Another problem that seeks to solve the invention is that of allowing an automatic correction of the inclination of the bucket compatible with the use of a more ergonomic hydraulic manipulator than a mechanical manipulator.

Statement of the invention

• deux bras parallèles articulés par rapport au châssis ;
• un godet articulé par rapport aux bras ;
• un ensemble de biellettes formant, avec une portion du godet et des bras, un parallélogramme déformable ;
• un vérin de godet apte à être commandé pour provoquer la déformation du parallélogramme déformable afin d'assurer l'orientation du godet par rapport aux bras;
• un mécanisme de came déplacé par une barre de liaison reliée par une extrémité au parallélogramme déformable, de sorte que la position de la came est fonction de l'orientation du godet par rapport au châssis.

The invention therefore relates to a public works machine of the "loader" type. Such a machine comprises a chassis and work equipment. Work equipment includes:

• two parallel arms articulated relative to the chassis;
• a bucket articulated relative to the arms;
• a set of links forming, with a portion of the bucket and the arms, a deformable parallelogram;
• a bucket cylinder capable of being controlled to cause the deformation of the deformable parallelogram to ensure the orientation of the bucket relative to the arms;
• a cam mechanism moved by a connecting bar connected at one end to the deformable parallelogram, so that the position of the cam depends on the orientation of the bucket relative to the chassis.

• un circuit de commande hydraulique permettant l'alimentation du vérin de godet par l'intermédiaire d'un distributeur commandé par un manipulateur hydraulique délivrant une pression de commande ;
• un dispositif hydraulique permettant de générer une pression de commande supplémentaire en fonction de la position de la came ;
• un sélecteur de circuit apte à transmettre au distributeur la pression la plus élevée entre la pression de commande délivrée par le manipulateur, et la pression de commande supplémentaire,

de sorte que l'orientation du godet est maintenue dans une position évitant son renversement inopiné vers l'arrière, quelles que soit les commandes exercées par le conducteur sur le manipulateur.According to the invention, this machine is characterized in that it also comprises:

• a hydraulic control circuit allowing the feeding of the bucket cylinder via a distributor controlled by a hydraulic manipulator delivering a control pressure;
• a hydraulic device making it possible to generate an additional control pressure as a function of the position of the cam;
• a circuit selector capable of transmitting to the distributor the highest pressure between the control pressure delivered by the manipulator, and the additional control pressure,

so that the orientation of the bucket is maintained in a position preventing its unexpected overturning to the rear, whatever the commands exerted by the driver on the manipulator.

In other words, the link bar ensures the mechanical return of information the angle between the arm and the link of the deformable parallelogram. This bar link causes the rotation of a cam which acts on a hydraulic valve. This valve delivers a pressure which, if it is higher than that delivered by the manipulator, takes precedence over the latter so that the distributor corrected the bucket cylinder.

It is therefore a correction which produces no mechanical effect in the user manipulator, which improves operating comfort. In practice, the circuit selector is placed on the portion of the hydraulic circuit which ensures the dumping of the bucket Indeed, it is of paramount importance that the bucket does not tip over backwards when it is lifted during the loading. Thus, the correction device generates a control pressure which is compared with the pressure from the manipulator hydraulic when the latter is controlled for raising the arms.

Brief description of the drawings

La figure 1 est une vue générale de côté d'un engin du type chargeuse/pelleteuse.

La figure 2 est une vue de côté de l'équipement de travail de la chargeuse de la figure 1 montrée dans deux positions différentes des bras.

La figure 3 est une vue en perspective sommaire du mécanisme de came conforme à l'invention.

La figure 4 est un schéma du circuit hydraulique de commande du vérin de godet.

La figure 5 est un diagramme montrant les variations de la pression de commande issue du manipulateur et la pression de commande complémentaire, en fonction du déplacement de la barre de liaison.

The manner of carrying out the invention as well as the advantages which result therefrom will emerge clearly from the description of the embodiment which follows, supported by the appended figures in which:

Figure 1 is a general side view of a loader / backhoe type machine.

Figure 2 is a side view of the work equipment of the loader of Figure 1 shown in two different positions of the arms.

Figure 3 is a summary perspective view of the cam mechanism according to the invention.

FIG. 4 is a diagram of the hydraulic circuit for controlling the bucket cylinder.

FIG. 5 is a diagram showing the variations of the control pressure from the manipulator and the additional control pressure, as a function of the displacement of the connecting bar.

How to realize the invention

As already mentioned, the invention relates to a public works machine having a "loader" function, for example a "backhoe loader" as illustrated in FIG. 1. In its front part, this machine (1) comprises a work equipment (2) enabling it to perform the function of loader. This work equipment (2) mainly comprises two arms (3) located on the side and other of the machine. By their rear ends (4), these arms (3) are articulated on the chassis (5). These arms (3) have a slightly curved shape so that their front ends (6) are located substantially at ground level in the lowest position of the arms (3). These arms (3) can be moved under faction two arm cylinders (7) also located on either side of the chassis (5). These cylinders (7) are articulated by one end (8) on the chassis, and by their end opposite (9) to the main arms (3), substantially at the median level (10) of these last.

At their front ends (6), the main arms (3) receive a bucket (15). This bucket (15) is articulated relative to the arms (3), so that it can be tilted at different angles. In this way, the opening (16) of the bucket can be oriented either forwards when it comes to penetrating materials (17), or backwards when the cup (15) is filled and it is moved.

In the illustrated form, the work equipment (2) also comprises two rods (20, 21) which form, with the extremal part of the arm (3) and part of the cup (15), a deformable parallelogram. More specifically, the equipment work (2) comprises a first rear link (20) which is articulated by its lower end (22) on the main arm (3). Equipment also includes a front link (21) articulated by its lower end (23) on the bucket, in a point located at a level higher than the articulation point (13) of the bucket (15) by relative to the arms (3). The two links (21) front and rear (20) are articulated with each other at their upper ends (25). So when the orientation of the bucket (15) varies relative to the arms (3), the parallelogram deformable including the links (20, 21) deforms. This deformation of the deformable parallelogram is caused by the action of a bucket cylinder (27). This bucket cylinder (27) has its rod (28) which is articulated on the bucket (15), substantially between the articulation point (23) of the front link (21) and the point hinge (13) of the bucket relative to the arms. The chamber (29) of the cylinder bucket (27) is connected in turn to the common point of articulation (25) of the two front (21) and rear (20) links. Thus, when an effort is exerted by the actuator bucket (27), the latter causing the point to approach or move away joint articulation (25) of the rods relative to the bucket (15), and therefore the deformation of the deformable parallelogram, and therefore, the variation of the inclination of the bucket (15) relative to the arms (3).

As already mentioned, the invention makes it possible to control this cylinder. bucket (27) so as to automatically correct the inclination of the bucket (15) whatever the position of the arms (3). So, to perform this function, the work equipment comprises a connecting bar (30) which extends along the main arm (3), substantially from the area where the rear link is articulated (20), and up to the point of articulation (8) of the arm (3) relative to the chassis (5). The front end (31) of this connecting bar (30) is articulated on the link rear (20), at the point of articulation (32).

The other end (33) of the connecting bar (30) is itself articulated substantially at the point of articulation (8) of the arm (3) relative to the chassis (5). More precisely, this end of this connecting bar is articulated on a cam as illustrated in FIG. 3. Thus, the end (33) of the connecting bar is articulated with respect to the cam (35) at the level of the branch (36) comprising a through opening (37). This cam (35) is mounted with a capacity of pivoting around a yoke (40) itself secured to the frame (5). The rotation of the cam (35) relative to the yoke (40) takes place around the through axis (41) the opening (41) provided for this purpose in the cam (35).

The cam (35) has a curved surface (43) each point of which is at a different distance from the axis of rotation (41) of the cam. This curved surface (35) comes into contact with a lever (45) itself articulated relative to the yoke (40) about an axis of rotation (46). This lever has a groove (47) whose walls (48, 49) come from either side of the cam (35), to prevent the latter does not deviate. This groove (47) is crossed by a rod (50) connecting the two walls (48, 49). The curved surface (43) of the cam (35) comes into contact with this rod (50).

During its movement, the lever (45) comes into contact with the crew mobile (51) of a hydraulic remote control (52). So, during its movement, the cam (35) pushes the lever (45), while return means not shown located inside the hydraulic remote control press this lever (45) against the cam (35). This hydraulic remote control (52) is therefore controlled as a function of the position of the lever (45), that is to say of the cam (35), and therefore the movement of the link bar (30), itself reflecting the inclination of the bucket (15).

This hydraulic remote control (52) is inserted in the circuit of hydraulic control illustrated in Figure 4. More specifically, this remote control hydraulic (52) is connected upstream to the main pressure source which is the pump (53). Downstream, this hydraulic remote control (52) is connected to a selector circuit (54), which ensures the selective connection between on the one hand, the distributor (55) of the bucket cylinder (27), and secondly, the outlet (56) of the hydraulic remote control (52), i.e. the output (57) of the control manipulator (58). More specifically, this control manipulator (58) has a pressure supply (59) from the main pump (53), and two outlet (57, 60) each corresponding to a direction of orientation of the bucket. The first one outlet (60) corresponds to the bucket lifting control, while the second outlet (57) corresponds to the bucket spill command.

Thus, the circuit selector (54) transmits to the distributor (55) the pressure which is the most important between the control pressure of the manipulator (58) and the pressure delivered by the hydraulic remote control (52). It is this pressure that then acts on the distributor slide (61) which causes the cylinder to move bucket (27).

Thus, when the pressure delivered by the manipulator (58) is greater than that from the hydraulic remote control (52) is the pressure value from the manipulator (58) which acts on the distributor (55). Conversely when the inclination of the bucket induces a displacement of the cam (35) such that the pressure delivered by the hydraulic remote control (52) is greater than that from the manipulator (58), this correction pressure from the remote control hydraulic (52) acts on the distributor (55). In practice, the control law of the hydraulic remote control is illustrated in Figure 5 in which we observe that the dotted curve (65) illustrating the value of the pressure as a function of the cam stroke is located above the curve in solid lines (66) corresponding to the value of the pressure from the hydraulic manipulator (58) in depending on the stroke of the latter.

In practice, during the loading operation, the driver places his bucket (15) in such a way that it has its opening (16) directed towards the front, in order to fill the cup. It then acts on the manipulator (58) to cause the backward pivoting of the bucket (15). The pressure from the manipulator (58) is greater than the pressure from the hydraulic remote control (52), which is null since the hydraulic remote control is not activated. Subsequently, when the main arms (3) are raised, as illustrated in Figure 2, the bar link (30) moves, therefore causing the movement of the cam (35). From from a certain height, the pressure from the T2 hydraulic remote control therefore exceeds that delivered by the manipulator (58), and it is this pressure which, via the circuit selector (54), acts on the distributor (55), to cause feeding the bucket cylinder (27) in the direction of an orientation of the latter forward, as shown in the upper part of Figure 2.

In other words, the system automatically compensates for the inclination of the bucket to prevent the latter from spilling backwards, if it remains in the incline initial, corresponding to that of the lower part of Figure 2.

It appears from the above that the machine according to the invention has the essential advantage of allowing automatic correction of the inclination of the bucket, which is insensitive to the level of the control manipulator. This correction driver safety increases because the risk of falling backward material is eliminated.

Claims (2)

1. A construction engineering machine (1) of the loader type, comprising a chassis (5) and work equipment (2) which includes :

   two parallel arms (3) articulated with respect to the chassis (5);

   a bucket (15) articulated with respect to the arms (3) ;

   a set of link rods (20, 21) forming, with a portion of the bucket (15) and of the arms (3), a deformable parallelogram ;

   a bucket actuator (27) designed to be controlled in order to cause deformation of the deformable parallelogram so as to orientate the bucket (15) with respect to the arms (3) ;

   a cam mechanism (35) moved by a connecting bar (30) connected by one end (31) to the deformable parallelogram so that the position of the cam (35) is dependent on the orientation of the bucket (15) with respect to the chassis (5),

   characterized in that it also comprises :

   a hydraulic control circuit allowing the bucket actuator (27) to be supplied via a directional control valve (55) controlled by a hydraulic manipulator (58) delivering a control pressure ;

   a hydraulic device (52) allowing the generation of an additional control pressure according to the position of the cam (35);

   a circuit selector (54) able to transmit to the directional control valve (55) the higher of the control pressure delivered by the manipulator (58) and the additional control pressure,

   so that the orientation of the bucket (15) is kept in a position that prevents its unwanted tipping backward, regardless of the commands exerted on the manipulator (58) by the driver.
2. The machine as claimed in claim 1, characterized in that the circuit selector (54) is arranged on the fraction of the hydraulic control circuit concerned with the tipping-out of the bucket (15).

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