FR2701801A1 - Hydraulic device for adjustable relief of the weight of a working implement bearing on a flat surface and application to mobile assemblies with mounted tools - Google Patents

Abstract

- Relief of the bearing load of a mounted tool. - The device comprises: - a hydraulic system feeding the converter, composed of at least: . a source (16) for providing hydraulic fluid under a pressure, . a main circuit (15) for supplying the converter, . a secondary circuit (30) for supplying the converter connected up in parallel from the main circuit, - and a supply unit (33) under an adjusted pressure which is less than the pressure controlling the secondary circuit. - Application to tools carried by mobile structures for carrying out work relative to the ground.

Description

1 osrnF Im: ADJUSTABLE DIFFERENCE WEIGHT OF ONE (xJnLIz WORK IN
SUPPORT WR A PLAN AND APPLICATION TO MOBILE ASSEMBLIES WITH PORTABLE TOOLS
The present invention relates to work tools of the carried type intended to be placed in abutment with respect to a set or unset plane, of continuous or discontinuous nature, horizontal, vertical or inclined and with respect to which a work must be executed.

 As a preferred, non-limiting application, the invention relates, more specifically, to tools of any type and of any kind used for the execution of work related to the ground, such as those for snow removal, grooving, scraping, cutting. road surfaces or those that can be qualified by the generic term of agricultural and including brushcutting, mowing, tedding, etc ...

 In the above field, the working tools, whether they are blades, teeth or hammers, are arranged or mounted on a load-bearing framework which is adapted at the end of work equipment carried by a movable motor structure. .

 Such an assembly involves at least one hydraulic energy transformer which can be interposed between the support structure and the work equipment or between some of the articulated segments constituting such equipment, or even between this equipment and directly the work tool.

 This or these hydraulic energy transformers have, among other things, the function of making it possible to move the working tool away from or closer to the support plane at the level of which the intervention must occur.

 As a general rule, the adjustment is carried out manually from the driving position by the attendant, who visually assesses how high, relative to the support surface, the working tool should be kept.

 Such a method is certainly not advisable because of at least two negative aspects which are attached to it.

 The first is that in such a situation, the working tool is brought without contact with the support surface, so that the tremors caused by the movement of the carrier structure must be supported by the energy transformer (s) hydraulics which are thus unnecessarily stressed at their joints, but also, and more damagingly, their seals.

 The second is that the operator is required to manually control, permanently, the gap between the work tool and the plan, when the latter varies locally, which is generally the case permanently in the field of work in relation to the ground.

 This procedure constitutes a constraint for the operator and does not lead to obtaining a satisfactory work result, given the fluctuating level of intervention which is conferred on the tool.

 This is the reason why, it has been recommended to provide the working tool with support means, of the skid or gauge wheel type, intended to rest on the support plane thus delimiting, with respect to the latter, a constant level difference allowing a more suitable work of the tool.

 If this way of proceeding has an advantage compared to the previous solution, it nevertheless suffers from certain disadvantages that should be eliminated.

 In the presence of support pads carried by the tool, the operator controls the supply of the hydraulic power transformer (s), so that all the weight load of the tool, or even of the equipment, rests on the plane by means of skids or other support means.

 The application of such a load, permanently, quickly leads to wear of the pads or other means which should be changed periodically.

 By acting in this way, the operator is still, nevertheless, forced to exercise manual control of the supply of the hydraulic power transformer (s), since for each modification of the level of the support plane, it is advisable to be able to rest the tool against the intervention plan.

 Furthermore, by establishing a load support directly on the tool, the operator relieves all that of the corresponding train of the vehicle which no longer has a maximum ground load and can thus lose functionality.

 The object of the invention is to remedy the above drawbacks by proposing a solution allowing the introduction of a correction factor and lightening of load in the support of the tool on the work surface, such so that, automatically, such a light load factor is maintained, whatever the level variations of the support plane.

 Thus, by the subject of the invention, three fundamental advantages are provided.

 The first lies in the slightest wear of the pads or other support members, due to the lightening of the load which constrains them relative to the plane.

 The second is to obtain an automatic level adjustment, without the servant having to intervene manually.

 The third is that the lightening of the support load of the tool makes it possible to transfer the main part of this load to the train or the corresponding axle of the machine and thus to give the machine better grip characteristics on difficult soils.

 Another object of the invention is to offer a possibility of obtaining the above advantages without detracting from the main function of lifting-lowering-orientation which should be reserved in a privileged manner, when the working tool is adapted at the end of mobile equipment.

 Another object of the invention is to offer a possibility of bringing the above advantages into play, in a selective and multiple way on different energy transformers interposed between a work equipment on which several tools are adapted.

 Thus, by such a means, it becomes possible to control, automatically, the adjustable lightening of each tool by bringing into play, if necessary, equally different lightening factors.

To achieve the above objectives, the hydraulic device according to the invention is characterized in that it comprises:
- a hydraulic supply network for the transformer, composed
at least:
a source of hydraulic fluid supply under a
pressure P,
a main transformer supply circuit
controlled by a distributor,
a secondary transformer supply circuit
connected in parallel from the main circuit,
on the other side of the distributor,
- and a power supply unit under a pressure set at p less than
the pressure P controlling the secondary circuit.

 The invention also relates to the preferred application of the above device to mobile assemblies with carried tools and, more specifically, also to assemblies whose tools are reserved for carrying out work of the type mentioned above.

 Various other characteristics will emerge from the description given below with reference to the appended drawings which show, by way of nonlimiting examples, embodiments and implementation of the subject of the invention.

 Fig. 1 is a schematic view illustrating the application of the device.

 Fig. 2 is a diagram corresponding to the device of the invention.

 Fig. 3 is a diagram similar to FIG. 2, but showing an alternative application.

 The hydraulic device according to the invention is intended to allow the adjustable lightening of the weight of a working tool 1 intended to rest, by support pads 2, on a plane 3 at which an intervention must be carried out. I1 must be considered that the support pads 2 could be replaced by any other equivalent member and, for example, by a gauge wheel.

 Fig. I shows an example of a preferred but non-limiting application in which the tool t is constituted by an agricultural working device, in the general sense of the term, such as a brush-cutting, mowing, tedding, etc. device.

 The hydraulic device is designed to be adapted to an assembly, of the type in which the tool I is carried relative to the plane 3. By carried, it is meant any structural arrangement in which the tool 1 can be moved away from or closer to the plane 3 with respect to a support structure S which may or may not be located on plane 3 also.

 In the intended application, the carrying structure S is constituted by a mobile machine, such as an agricultural tractor or the like, the chassis of which is provided with working equipment 4, generally of the articulated type, at the end of which the tool 1 is suitable.

 Such structures involve various assemblies and that illustrated in FIG. 1 is given only by way of illustration.

 In a known manner, the mobile equipment 4 can involve a first articulated segment 5, generally called an arrow, and a second articulated segment 6, generally called an arm or a pendulum. The equipment 4 comprises a first series 7 of hydraulic energy transformers, generally based on cylinders with rectilinear stroke making it possible to control the movement of the boom in one or the other direction of the arrow f1.

 Such equipment most often also includes a second series of hydraulic power transformers 8, also based on rectilinear jacks, making it possible to control the movement in one or the other direction of the arrow f2 of the arm 6 relative to arrow 5. Generally, such equipment can also involve a third series of hydraulic power transformers 9 which are interposed between the tool 1 and the arm 6. Such transformers, also based on jacks with rectilinear stroke, can allow relatively to move the working tool in the direction of arrow f3.

 li must be considered, within the meaning of the invention, on the basis of the schematic representation provided by FIG. 1, that the operator can act on any one of the series of transformers 7, 8 or 9 to adjust the relative position of the tool 1 relative to the plane 3. The hydraulic device of the invention described here -after must therefore be considered as being able to be implemented or in service to control the hydraulic supply of the energy transformers of any one of the series 7, 8 or 9.

 The diagram according to fig. 2 shows the hydraulic device according to the invention for supplying a hydraulic energy transformer 7, 8 or 9 from a main circuit 15 comprising a pressure line 16 coming from a source 17 of fluid supply hydraulic under pressure P, from a tank 18. The main circuit 15 also includes a return line 19.

 Lines 16 and 19 lead to a distributor 20, the structure of which is chosen according to the type of energy transformer which can be double-acting or single-acting with or without elastic return. In the example illustrated, the distributor 20 has three positions, while the transformer is of the single-acting type without elastic return, but with positive feed control reversal by an inverting slide 21. For the following, it is retained that the main circuit comprises, beyond the distributor 20, a supply line 22 leading to the large chamber 23 of the transformer 7, 8 or 9.

 The hydraulic device for adjustable lightening of the weight of the working tool 1 involves a secondary circuit 30 comprising a pressure line 31 connected to be followed on line 16 upstream of the distributor 20 and a return line 32 connected to be followed on line 19. The secondary circuit also includes a controlled power supply 33 to which the lines 31 and 32 terminate and a power supply line 34 connecting the block 33 bypass to the power supply line 22.

 The power supply 33 includes a pressure circuit breaker 35 arranged between lines 31 and 32. The block 33 includes, from line 31 and downstream of the pressure circuit breaker 35, a non-return valve 36 mounted on a pressure line 37 on which is located a connection 38 leading to a hydropneumatic accumulator 39. Line 37 comprises, between the accumulator 39 and the non-return valve 36, a control line 40 connected to the contactor-circuit breaker pressure 35.

 Line 37 also comprises, downstream of the valve 36, a pressure reducer 41 which is adjusted so as to cause a pressure p lower than that P of the main circuit to prevail in the secondary circuit 30, and more particularly the line 34 15. The pressure reducer 41 may consist of a preset cartridge or alternatively of equipment that can be adjusted by direct action or by remote intervention. In the latter case, the pressure reducer 41 can be coupled to a pressure relief valve 42 which is mounted on a branch 43 leading to a return line 44 leading to the cover 18. The branch 43 can be used for mounting a display 45 upstream of which is placed a valve or an isolation valve 46.

 The outlet 47 of the pressure reducer 41 is connected to the secondary supply line 34 leading to the supply line 22.

 The block 33 also comprises a bypass line 48 established on either side of the pressure reducer 41 with the installation of a non-return valve 49 preventing the circulation of the hydraulic fluid in the direction of line 37, outlet 47.

 The hydraulic device for adjustable lightening of the weight of a working tool, such as tool 1 and described above, operates as follows.

 The hydraulic power transformer 7, 8 or 9 can be controlled by the main supply via the distributor 20 from the source 17 which provides a permanent pressure P. This pressure P is also transmitted by the line 31 to the secondary circuit 30 which self-adjusts up to the pressure p set by the reducer 41 due to the presence of the accumulator 39 and the contactor-circuit breaker 35. In fact, the pressure P, reduced to the value p, is established inside the block 33 and charges the accumulator 39 until the value p is reached, which then causes, by the control line 40, the switching of the contactor-pressure breaker 35 which short-circuits the block 33 for returning the hydraulic fluid from line 31 to the cover 18 via the return line 32.

 The hydraulic device is thus in a state to enter into function, as soon as the tool 1 has been brought to bear on the plane 3. To this end, the distributor 20 is actuated to connect the jack 7 to the return circuit 19. The general weight of the equipment 4 and the tool 1 causes the application of the latter on the plane 3.

 In such a case and since the block 33 is in functional state, it is considered that a fluid under pressure p is supplied to the line 34 which maintains in the chamber 23 a supply of a fluid under pressure p.

 In this way, the application load of the tool 1 on the plane 3 is limited to the difference between the bearing weight of the mobile assembly and the opposing supply at limited pressure which opposes it. Thus, by adjusting the reducer 41, it becomes possible to reduce the application load to a predetermined value without involving manipulation by the operator.

 Assuming that during the movement of the mobile machine S the level of the plane 3 relatively lowers, the tool 1 will be biased in the same direction while maintaining contact by the support means 2. This will have the effect to increase the volume of the chamber 23 and to admit into the latter an influx of hydraulic fluid under pressure p, from the block 33 to maintain the factor of lightening of the weight of the tool as a function of the setting of the reduction gear 41 .

 Assuming that the path of the mobile machine S involves raising the level of the plane 3, the tool 1 will be raised by the contact of the parts 2. The volume of the chamber 23 will be reduced accordingly by putting the fluid contained under an intermediate pressure between pressure P and pressure p. In such a case, this intermediate pressure causes the non-return valve 49 to open to be absorbed by the accumulator 39 and allow the preset pressure p corresponding to the desired weight reduction factor to remain in the chamber 23.

 li can be considered a hypothetical scenario in which the reflux of the chamber 23 cannot be absorbed by the accumulator 39. In such a case, the pressure in the block 33 can then increase up to the triggering threshold of the valve 42 diverting the fluid towards the return to the tank, to maintain in the block a functional pressure p.

 Thus, as has just been demonstrated, the hydraulic device according to the invention makes it possible to support a working tool on an intervention plan with a load factor reduced relative to the weight of this tool, possibly supplemented by that of the equipment carrying it. In this way, a significant reduction in wear of the support means can occur, as well as a reduction in the general load which is imposed on the joints and the energy transformers.

 In addition, this reduction makes it possible to transfer the residual load to the train or the corresponding axle of the machine, which in this way benefits from better progress conditions on difficult terrain.

 The hydraulic device according to the invention also makes it possible to maintain the tool 1 at a constant determined level of the plane 3 without operator intervention, whatever the level variations which may occur.

 The operator may be faced with a need to adjust this light load factor according to certain operating conditions. In this regard, it suffices to act on the pressure relief valve 42 to remotely adjust the regulator 41, in order to show by the display 45 the pressure value p which is sought.

 According to the invention, it is advantageously provided to have, between the outlet 47 and the line 34, an isolation valve 50 making it possible to interrupt the connection between the block 33 and the jack 27. The control of this isolation valve 50 may be manual or, more advantageously still, coupled with that of the distributor 20, being, however, inversely conjugated in opening-closing.

 Thus, as soon as the distributor 20 is ordered to open, the isolation valve 50 is closed, which makes it possible to favor the supply of the transformer 7, 8 or 9 via the main circuit 15.

 The isolation valve 50 also makes it possible, in the open position, to allow the lightening factor to remain by the chamber 23, when the tool 1 is carried away from the plane 3, as is, for example, the case. road configuration.

This arrangement makes it possible to absorb and protect the working members by reducing and authorizing the load fluctuations which inevitably occur during the road progression of the mobile assembly 3.

 Fig. 3 shows an additional arrangement consisting in providing a block 51 on the block 33 on the line 37 between the valve 36 and the reduction gear 41. Such a branch connection makes it possible to connect, by a connection 52, the block 33 to a parallel block 33a comprising a own pressure reducer 41a, a possible pressure relief valve 42a, a possible display 45a and a possible isolation valve 50a. Such a parallel block 33a makes it possible, via a supply line 34a, to supply a transformer 7a, 8a, 9a different from the transformer 7, 8, 9 and which is also supplied by a distributor 20a from the main circuit 15.

 Such an arrangement allows selective connection for several energy transformers, by making use of a possible different pressure p for each of them.

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

Claims (13)

CLAIMS:  lower than the pressure (P) controlling the secondary circuit.  - And a supply block (33) under a regulated pressure (p)  on the other side of the distributor,  connected in parallel from the main circuit and  a secondary circuit (30) for supplying the transformer  controlled by a distributor (20),  a main circuit (15) for supplying the transformer  a pressure (P),  a source (16) for supplying hydraulic fluid under  at least::  - a hydraulic supply network for the transformer, composed  characterized in that it comprises:  I - Hydraulic device for adjustable lightening of the weight of a working tool (1) resting on a plane (3), tool carried by support equipment (4) and comprising support means (2) brought to rest on the plane by means of at least one hydraulic power transformer (7, 8 or 9) capable of moving the tool away or closer to the plane,  2 - Hydraulic device according to claim 1, characterized in that the block comprises:  - a pressure contactor (35) interposed between a  pressure line (31) and a return line (32) of the circuit  main,  - downstream of the contactor-circuit breaker and on the pressure line, a  non-return valve (36),  - a pressure reducer (41) placed downstream of the non-return valve,  - a connection of a hydropneumatic accumulator (39) provided  bypass between the non-return valve and the reduction gear  pressure,  - And a control line (40) established between, on the one hand, the valve  check valve and reducer and, on the other hand, the contactor  circuit breaker.  3 - Hydraulic device according to claim 1 or 2, characterized in that the block (33) comprises an isolation valve (50) disposed downstream of the reducer.  4 - Hydraulic device according to claim 3, characterized in that the isolation valve (50) is placed downstream of a bypass line (48) established between the bypass (38) of the accumulator and the outlet (47 ) of the pressure reducer, such a line being provided with a non-return valve (49) in the direction of accumulator-valve circulation.  5 - Hydraulic device according to claim 3 or 4, characterized in that the isolation valve (50) is coupled to and inversely synchronized in opening-closing with the distributor of the main circuit (20).  6 - Hydraulic device according to one of claims 1 to 3, characterized in that the block (33) comprises, between the non-return valve (36) and the pressure reducer (41), a branched branch (51) of connection to at least one parallel block (33a), provided with a pressure reducing valve (41a) and a bypass check valve (49a), connected to the main circuit of a second transformer (7a, 8a, 9a ) by a secondary circuit.  7 - Hydraulic device according to claim 6, characterized in that the parallel block (33a) is provided with an isolation valve (42a) placed downstream of the pressure reducer (41a) and inversely combined with the distributor (20a) controlling the main circuit of the second transformer.  8 - Hydraulic device according to one of claims 1 to 3 and 6 or 7, characterized in that the block (33, 33a) comprises an adjustable pressure reducer (41, 41a).  9 - Hydraulic device according to claim 8, characterized in that the adjustable pressure reducer (41, 41a) is coupled to an adjustable pressure relief valve (42, 42a) placed on a return line (44, 44a).  10 - Hydraulic device according to claim 9, characterized in that the pressure relief valve (42, 42a) is mounted on a bypass connected to the pressure reducer leading to a display (45, 45a) through a valve isolation (46, 46a) and connected to the return line.  11 - Application of the hydraulic device according to one of claims 1 to 10 to mobile assemblies with carried tools.  12 - Application according to claim 11, characterized in that the hydraulic device acts on at least one energy transformer (9) interposed between the tool (1) and work equipment (4) mounted on a support structure (S ).  13 - Application according to claim 11, characterized in that the hydraulic device acts on at least one energy transformer (7 or 8) interposed between a support structure (S) and a work equipment (4) carrying the tool ( 1).