Piece of equipment for the control of the displacement of a working tool of an agricultural vehicle

Abstract

The piece of equipment (1) for the control of the displacement of a working tool of an agricultural vehicle, comprises: - a load-bearing element associable with an agricultural vehicle; - at least one driving element (2) connectable to a working tool; - at least one control lever (3, 4) of the driving element (2); - pumping means (5) of a working fluid under pressure; - one discharge tank (6); - one fluid-operated cylinder (7) two chambers (8, 9) separate from each other, of which one is a lifting chamber (8) and one is a descending chamber (9); - at least one movement assembly (10) comprising main valve means (11) adapted to set in communication / isolate the fluid-operated cylinder (7) with the pumping means (5) and with the discharge tank (6), wherein the distributor element (12) is operationally connected to the control lever (3, 4); and wherein the main valve means (11) are movable between at least one lifting position, wherein they set the pumping means (5) in communication with the lifting chamber (8) and the descending chamber (9) with the discharge tank (6), and a descending position, wherein they set the descending chamber (9) in communication with the pumping means (5) and the lifting chamber (8) with the discharge tank (6).

Description

[0001] PIECE OF EQUIPMENT FOR THE CONTROL OF THE DISPLACEMENT OF A WORKING TOOL OF AN AGRICULTURAL VEHICLE

[0002] Technical Field

[0003] The present invention relates to a piece of equipment for the control of the displacement of a working tool of an agricultural vehicle.

[0004] Background Art

[0005] The use of a so-called “three-point hitch”, which is attached to the rear of the vehicle itself to support a working tool, e.g. the type of a plow, has long been known in the agricultural sector.

[0006] In fact, three-point hitching devices are frequently used to connect tools or auxiliary vehicles to the rear of the agricultural vehicle.

[0007] Three-point hitching devices of known type generally comprise two lifting arms, hinged on one side to the towing vehicle and associated on the opposite side to the working tool, where each lifting arm is connected to a relevant lifting rod associated, on the opposite side, with a relevant driving element responsible for the actual movement of the lifting arm.

[0008] More particularly, the driving elements are in turn associated with a load-bearing element, connectable to the towing vehicle, and are connected to a fluid- operated cylinder that controls the lifting or lowering thereof as needed.

[0009] The three-point hitching devices then involve the presence of a strut having one end associated with the above load-bearing element and the opposite end connectable to the working tool.

[0010] As anticipated above, depending on the work requirements, the driving elements are lowered, e.g., to make the working tool penetrate the ground, raised, e.g., in the phases of displacement of the towing vehicle, or held in the position achieved. Equipment known to date for the control of the displacement of the working tool connected to the three-point hitch of an agricultural vehicle involves feeding the chamber of the fluid- operated cylinder that commands the lifting of the driving elements.

[0011] This means that when it is necessary to lift the working tool, pressurized oil is sent to the fluid- operated cylinder so as to command the upward movement of the driving elements while, when it is necessary to perform the downward movement of the working tool, the lifting chamber of the fluid- operated cylinder is connected to a discharge tank so that, due to its weight, the driving elements move downwards. Holding the working tool in position is achieved by breaking the connection of the fluid- operated cylinder to the discharge tank.

[0012] The equipment known to date also allows a predefined intensity of effort to be set on the working tool. Thus, in this case, the displacement of the working tool upwards or downwards is automatically controlled by means of a mechanical linkage that “reads” the effort on the working tool and adjusts its working depth accordingly, so as to vary the degree of penetration into the ground and keep the intensity of the effort thereon almost constant.

[0013] However, the known type of equipment has some drawbacks.

[0014] This, in fact, does not allow effective action of the working tool in the case of particularly hard soils. This is because the force that can be exerted downward is limited and depends solely on the force of gravity due to the weight of the masses involved.

[0015] This also limits the descent speed of the driving elements, particularly in the case of the absence of the working tool or of lightweight working tools.

[0016] Yet another drawback of equipment of known type is that in the operating condition wherein the working tool is held at a predetermined height, it is still free to move upwards.

[0017] Description of the Invention

[0018] The main aim of the present invention is to devise a piece of equipment for the control of the displacement of a working tool of an agricultural vehicle which allows the downward force exerted by the working tool to be varied.

[0019] Within this aim, one object of the present invention is to increase, compared with equipment of known type, the descent speed of the working tool.

[0020] One object of the present invention is to improve, compared with the equipment of known type, the handling of the positioning of the tool’s working depth according to the effort intensity set. Yet another object is to be able to use the working tool for lifting the towing vehicle.

[0021] Still one object of the present invention is to enable the blocking of the working tool, either in the lifting or descending direction, at the desired height above the ground.

[0022] Another object of this invention is to devise a piece of equipment for the control of the displacement of a working tool of an agricultural vehicle which allows the aforementioned drawbacks of the prior art to be overcome within the framework of a simple, rational, easy and effective to use as well as cost-effective solution. The aforementioned objects are achieved by this piece of equipment for the control of the displacement of a working tool of an agricultural vehicle.

[0023] Brief Description of the Drawings

[0024] Other characteristics and advantages of the present invention will become more apparent from the description of a preferred, but not exclusive, embodiment of a piece of equipment for the control of the displacement of a working tool of an agricultural vehicle, illustrated by way of an indicative, yet non-limiting example, in the accompanying tables of drawings in which:

[0025] Figures 1 to 3 are schematic representations of the hydraulic circuit of a piece of equipment according to the invention, under three different operating conditions, in a first embodiment;

[0026] Figures 4 through 6 are schematic representations of the hydraulic circuit of a piece of equipment according to the invention, under three different operating conditions, in a second embodiment.

[0027] Embodiments of the Invention

[0028] With particular reference to these figures, reference number 1 globally denotes a piece of equipment for the control of the displacement of a working tool of an agricultural vehicle.

[0029] The piece of equipment 1 comprises a load-bearing element (not shown in the figures) associable with an agricultural vehicle, at least one driving element 2 associated with the load-bearing element and connectable to a working tool (also not shown in the figures), such as a plow or the like, and at least one control lever

[0030] The piece of equipment 1 then comprises pumping means 5 of a working fluid under pressure (e.g., oil), at least one discharge tank 6 and at least one fluid- operated cylinder 7 kinematically connected to the driving element 2. The fluid- operated cylinder 7 comprises an internally hollow body 7a and a piston 7b housed within it in a sliding manner, wherein the piston 7b and the body 7a bound two mutually separate chambers 8 and 9, of which one is a lifting chamber 8 and one is a descending chamber 9. In particular, the piece of equipment 1 comprises at least two driving elements 2 hinged to the load-bearing element and movable in rotation with respect thereto around a relevant axis.

[0031] The driving elements 2 can be connected to an individual fluid- operated cylinder 7 or each of these driving elements 2 can be kinematically connected to a related fluid- operated cylinder 7. Appropriately, the outflow of the piston 7b from the body 7a due to the feeding of the lifting chamber 8 with the working fluid results in the upward rotation of the relevant driving element, while the movement in the opposite direction of the piston 7b results in the downward rotation of the driving element 2.

[0032] In more detail, the driving elements 2 are connected via relevant tie-rods to the lifting arms of a so-called “three-point hitch” that support the working tool.

[0033] The piece of equipment 1 is provided with at least one movement assembly 10 comprising main valve means 11 provided with at least one distributor element 12 which is movable to set in communication / isolate the fluid- operated cylinder 7 with / from the pumping means 5 and with / from the discharge tank 6, wherein the distributor element 12 is operationally connected to the control lever 3,4.

[0034] As will be described in more detail below, the displacement of the control lever 3,4 carried out manually by an operator causes, either directly or indirectly, a displacement of the distributor element 12 and, consequently, of the driving elements 2.

[0035] According to the invention, the main valve means 11 are movable by the distributor element 12 between at least one lifting position, wherein they set the pumping means 5 in communication with the lifting chamber 8 and the descending chamber 9 with the discharge tank 6, and one descending position, wherein they set the descending chamber 9 in communication with the pumping means 5 and the lifting chamber 8 with the discharge tank 6.

[0036] The connections of the lifting chamber 8 and of the descending chamber 9 with the pumping means 5 and with the discharge tank 6 are therefore reversed to the lifting position and the descending position, thus actively commanding the exit and re-entry of the piston 7b and the lifting and descent of the driving elements 2, respectively.

[0037] Preferably, the main valve means 11 are of the proportional type.

[0038] Appropriately, the main valve means 11 have an intermediate position between the lifting position and the descending position, wherein they interrupt the connection of the lifting chamber 8 and of the descending chamber 9 with both the pumping means 5 and with the discharge tank 6. In the intermediate position, therefore, the position achieved by the driving elements 2 is maintained.

[0039] More particularly, the movement assembly 10 comprises at least one first feeding line 13 of the lifting chamber 8 positioned between the main valve means 11 and the lifting chamber 8, and at least one second feeding line 14 of the descending chamber 9, positioned between the main valve means 11 and the descending chamber 9. The pumping means 5 are therefore set in communication alternately with the first feeding line 13 and with the second feeding line 14 in the lifting position and in the descending position, respectively.

[0040] Advantageously, the movement assembly 10 comprises further valve means 15 operationally connected to the main valve means 11 and movable between at least a first working position, wherein they interrupt the connection between the first feeding line 13 and the discharge tank 6, with the main valve means 11 in the lifting position, and at least a second working position, wherein they set the first feeding line 13 in communication with the discharge tank 6, with the main valve means 11 in the descending position. The further valve means 15 then move between the first working position and the second working position as a result of the displacement of the main valve means 11 between the lifting position and the descending position, respectively. In other words, the further valve means 15 are adapted to allow and prevent the outflow of the working fluid contained in the lifting chamber 8 in the descending position and in the lifting position of the main valve means 11, respectively.

[0041] Appropriately, the further valve means 15 are positionable, as a result of the attainment of the intermediate position by the main valve means 11, in a third working position, wherein they interrupt the connection between the first feeding line 13 and the discharge tank 6.

[0042] Preferably, the piece of equipment 1 comprises manual valve means 16 positioned between the second feeding line 14 and the discharge tank 6 and manually movable between a feeding position, wherein they isolate the second feeding line 14 from the discharge tank 6, and a discharge position, wherein they set the second feeding line 14 in communication with the discharge tank 6. The manual valve means 16 are therefore operable by the operator to set the descending chamber 9 in communication with the discharge tank 6 regardless of the position of the main valve means 11 , thereby preventing the descending chamber itself from being fed with the working fluid under pressure.

[0043] Advantageously, the movement assembly 10 comprises control valve means 17 positioned between the pumping means 5 and the discharge tank 6 and movable between a first position, wherein they open the connection with the discharge tank 6, and a second position, wherein they interrupt the connection with the discharge tank 6. On the control valve means 17 first elastic means 18 operate on one side and a first piloting line 19 operates on the opposite side, wherein the first elastic means 18 are adapted to counteract the displacement of the control valve means 17 from the first position towards the second position.

[0044] In the embodiment shown in Figures 1 to 3, the control valve means 17 are directly connected to the pumping means 5; therefore, in the first position, the control valve means 17 set the pumping means 5 in communication with the discharge tank 6, while in the second position they isolate the pumping means 5 from the discharge tank 6. In this embodiment, the first piloting line 19 is connectable to the first feeding line 13 in the lifting position of the main valve means 11 and to the second feeding line 14 in the descending position of the main valve means 11; in thus way, the first piloting line 19 is pressurized and commands the displacement of the control valve means 17 to the second position so that the working fluid under pressure can reach the fluid- operated cylinder 7. The first piloting line 19 is then connectable to the discharge tank 6 in the intermediate position of the main valve means 11 so as to allow the return of the control valve means 17 to the first position as a result of the action of said first elastic means 18.

[0045] More particularly, the first piloting line 19 communicates with a so-called “shuttle valve”, i.e., a valve communicating with two branches 19a, 19b which are separate from each other, the line allowing the working fluid to flow from the branch having the higher pressure. The connection between the branches 19a, 19b, the feeding lines 13 and 14 and the discharge tank 6 is made through the main valve means 11. In more detail, in the lifting position and in the descending position the main valve means 11 set the branches 19a and 19b in communication with the first feeding line 13 and with the second feeding line 14, one of which is set in communication with the pumping means 5 and the other with the discharge tank 6, so that the first piloting line 19 is pressurized while, in the intermediate position, the main valve means 11 set both branches 19a and 19b in communication with the discharge tank 6, so that the first piloting line 19 is depressurized.

[0046] Thus, in this first embodiment, all the flow rate from the pumping means 5 is sent to the fluid- operated cylinder 7 and to the discharge tank 6 in the second position and in the first position of the control valve means 17, respectively.

[0047] In the second embodiment shown in Figures 4 through 6, the movement assembly 10 comprises auxiliary valve means 20, positioned between the pumping means 5 and the main valve means 11, which are movable between at least one discharge position, wherein they set the pumping means 5 in communication with the discharge tank 6, and a feeding position, wherein they set the pumping means 5 in communication with the main valve means 11.

[0048] On the auxiliary valve means 20 operate second elastic means 21 and a second piloting line 22 communicating with the control valve means 17 on one side and, on the opposite side, a third piloting line 23 communicating with the pumping means 5; the action of the second elastic means 21 and of the pressure of the fluid along the second piloting line 22 are adapted to counteract the displacement of the auxiliary valve means 20 from the feeding position towards the discharge position.

[0049] In this second embodiment, the second piloting line 22 is set in communication with the discharge tank 6 when the control valve means 17 are in the first position and is connectable, when the control valve means 17 are in the second position, to the first feeding line 13 and to the second feeding line 14 in the lifting position and in the descending position of the main valve means 11, respectively. Therefore, when the main valve means 11 are arranged in the lifting position or in the descending position, the auxiliary valve means 20 are brought, as a result of the combined action of the second elastic means 21 and of the second piloting line 22 (which is under pressure) to the feeding position while, when the main valve means 11 are arranged in the intermediate position, the auxiliary valve means 20 are brought to the discharge position, as a result of the lack of pressure along the second piloting line 22 communicating with the discharge tank 6 through the control valve means 17 and of the pressure along the third piloting line 23.

[0050] More particularly, the second piloting line 22 also communicates with a so-called “shuttle valve”, i.e. a valve communicating with two branches 22a, 22b which are separate from each other and which valve allows the working fluid to flow from the branch having the higher pressure. In this case, one branch 22a is set in communication with the first feeding line 13 and the other branch 22b is set in communication with the second feeding line 14.

[0051] In this second embodiment, the branches 19a and 19b communicating with the first piloting line 19 are set in communication, in the lifting position of the main valve means 11, one with the branch 22a communicating with the first feeding line 13 and the other with the discharge tank 6 and, in the descending position, one with the branch 22b communicating with the second feeding line 14 and the other with the discharge tank 6. In the intermediate position of the main valve means 11, the branches 19a and 19b communicating with the first piloting line 19 are set in communication by means of the same main valve means 11 with the branches 22a and 22b communicating with the second piloting line 22; therefore, in this operating condition the first piloting line 19 is set in communication with the discharge tank 6. Preferably, the branches 19a and 19b communicate, in each position of the main valve means 11, with the branch 22a and with the branch 22b, respectively.

[0052] In this second embodiment, when the main valve means 11 move to the lifting position and to the descending position, the control valve means 17 move to the second position, thus isolating the second piloting line 22 from the discharge tank 6. The second piloting line 22 therefore pressurizes by bringing the auxiliary valve means 20 to the feeding position, thus allowing the working fluid to flow within the lifting chamber 8 and the descending chamber 9 respectively, and, consequently, the lifting and lowering of the driving elements 2. On the other hand, when the main valve means 11 are arranged in the intermediate position, the control valve means 17 move to the first position so as to connect the second piloting line 22 with the discharge tank 6 and, consequently, allowing the auxiliary valve means 20 to be displaced to the discharge position.

[0053] In this second embodiment, the whole flow rate of the pumping means 5 is sent to the discharge tank 6 when the auxiliary valve means 20 are placed in the discharge position, while the working fluid flow rate is biased towards the fluid- operated cylinder 7 when the auxiliary valve means 20 are placed in the feeding position.

[0054] Advantageously, the control lever 3,4 comprises at least a first control lever 3, and the piece of equipment 1 comprises first mechanical means 24 for connecting the first control lever 3 to the distributor element 12. More particularly, the first mechanical means 24, schematically shown in the figures, are of the type of a linkage which is operated as a result of the displacement of the first control lever 3 thereby exerting a thrust or pulling action on the distributor element 12 depending on the way of displacement of the first control lever itself. The first mechanical means 24 are then operationally connected to the driving elements 2, i.e., the displacement of the driving elements 2 induced by the distributor element 12 retroacts on the first mechanical means 24, moving them until a balancing position is achieved. In other words, the first mechanical means 24 are mechanically connected to the driving elements 2, so that the displacement of the latter induces the displacement of one of the elements constituting the relevant linkage. The first control lever 3 is, e.g., adapted to determine the height with respect to the ground of the driving elements 2 whereby, as a result of its displacement, the main valve means 11 then move from the intermediate position to the lifting position or to the descending position and return to the intermediate position once the set height is reached.

[0055] Preferably, the piece of equipment 1 comprises at least one abutment element 25 (schematically shown in the figures) operationally connected to the driving element 2 and to the working tool, the control lever 3,4 comprises at least one second control lever 4 and second mechanical means 26 are provided for connecting the second control lever 4 to the abutment element 25, wherein said second mechanical means 26 are operationally connected to the first mechanical means 24. In particular, the abutment element 25 and the driving element 2 are mechanically connected to each other by means of the working tool, so that the displacement of one causes the displacement of the other.

[0056] As a result of the operation of the second control lever 4, e.g. adapted to define the intensity of the effort on the working tool, the second mechanical means 26, e.g., of the type of a linkage, are operated upon causing them to be displaced with respect to the abutment element 25. This displacement in turn results in the movement of the first mechanical means 24 and the consequent operation of the distributor element as described above. The raising or lowering of the driving elements 2 caused by the displacement of the distributor element 12 results in a change in the load on the working tool and, therefore, on the abutment element 25 which consequently changes its position with respect to the second mechanical means 26 which in turn affects the first mechanical means 24 and, consequently, the distributor element itself. In this working condition, the main valve means 11 thus move almost continuously between the lifting / descending positions and the intermediate position depending on the load “sensed” by the abutment element 25.

[0057] It has in practice been ascertained that the described invention achieves the intended objects and in particular the fact is emphasized that the alternating connection of both chambers of the fluid-operated cylinder enables the active command of both lifting and lowering of the working tool.

[0058] This makes it possible to adjust the intensity of the force exerted downward by the working tool and, therefore, more effective penetration into the soil, which is particularly advantageous in the case of hard soils.

[0059] Additionally, in this way the working tool can be used for lifting the agricultural vehicle.

[0060] Sending the working fluid under pressure within the descending chamber also allows the descent phase of the working tool to be speeded up regardless of the weight of the tool and of the temperature of the working fluid.

[0061] In addition, the piece of equipment according to the invention allows the position of the working tool to be blocked in both the lifting and descending directions.

[0062] Again, the presence of the manual valve means allows the descending chamber to be discharged, thus enabling the fluid- operated cylinder to operate as a singleacting cylinder.

Claims

CLAIMS1) Piece of equipment (1) for the control of the displacement of a working tool of an agricultural vehicle, comprising: a load-bearing element associable with an agricultural vehicle; at least one driving element (2) connectable to a working tool; at least one control lever (3, 4) of said driving element (2); pumping means (5) of a working fluid under pressure; at least one discharge tank (6); at least one fluid- operated cylinder (7) comprising an internally hollow body (7a) and a piston (7b) housed within it in a sliding manner, wherein said piston (7b) and said body (7a) bound two chambers (8, 9) separate from each other, of which one is a lifting chamber (8) and one is a descending chamber (9), said fluid- operated cylinder (7) being kinematically connected to said driving element (2); at least one movement assembly (10) comprising main valve means (11) provided with at least one distributor element (12) which is movable to set in communication / isolate said fluid- operated cylinder (7) with / from said pumping means (5) and with / from said discharge tank (6), wherein said distributor element (12) is operationally connected to said control lever (3, 4); characterized by the fact that said main valve means (11) are movable as a result of the displacement of said distributor element (12) between at least one lifting position, wherein they set said pumping means (5) in communication with said lifting chamber (8) and said descending chamber (9) with said discharge tank (6), and a descending position, wherein they set said descending chamber (9) in communication with said pumping means (5) and said lifting chamber (8) with said discharge tank (6).2) Piece of equipment (1) according to claim 1, characterized by the fact that said main valve means (11) are of the proportional type.3) Piece of equipment (1) according to claim 1 or 2, characterized by the fact that said main valve means (11) have an intermediate position between said liftingposition and said descending position and wherein they interrupt the connection of said lifting chamber (8) and of said descending chamber (9) with said pumping means (5) and with said discharge tank (6).4) Piece of equipment (1) according to one or more of the preceding claims, characterized by the fact that said movement assembly (10) comprises at least one first feeding line (13) of said lifting chamber (8) positioned between said main valve means (11) and said lifting chamber (8), and at least one second feeding line (14) of said descending chamber (9), positioned between said main valve means (11) and said descending chamber (9), said pumping means (5) being alternately set in communication with said first feeding line (13) and with said second feeding line (14) in the lifting position and in the descending position, respectively.5) Piece of equipment (1) according to one or more of the preceding claims, characterized by the fact that said movement assembly (10) comprises further valve means (15) operationally connected to said main valve means (11) and movable between at least a first working position wherein they interrupt the connection between said first feeding line (13) and said discharge tank (6) with said main valve means (11) in the lifting position, and at least a second working position, wherein they set said first feeding line (13) in communication with said discharge tank (6) with said main valve means (11) in the descending position.6) Piece of equipment (1) according to claim 5, characterized by the fact that said further valve means (15) are positionable in a third working position, wherein they interrupt the connection between said first feeding line (13) and said discharge tank (6) with said main valve means (11) in the intermediate position.7) Piece of equipment (1) according to one or more of the preceding claims, characterized by the fact that it comprises manual valve means (16) positioned between said second feeding line (14) and said discharge tank (6) and manually movable between a feeding position, wherein they isolate said second feeding line (14) from said discharge tank (6) and a discharge position, wherein they set said second feeding line (14) in communication with said discharge tank (6).8) Piece of equipment (1) according to one or more of the preceding claims,characterized by the fact that it comprises control valve means (17) positioned between said pumping means (5) and said discharge tank (6) and movable between a first position, wherein they open the connection with said discharge tank (6), and a second position, wherein they interrupt the connection with said discharge tank (6), on said control valve means (17) operating first elastic means (18) on one side and a first piloting line (19) on the opposite side, said first elastic means (18) being adapted to counteract the displacement of said control valve means (17) from the first position towards the second position.9) Piece of equipment (1) according to claim 8, characterized by the fact that said control valve means (17) are directly connected to said pumping means (5) and by the fact that said first piloting line (19) is connectable to said first feeding line (13) in the lifting position of said main valve means (11) and to said second feeding line (14) in the descending position of said main valve means (11), so as to control the displacement of said control valve means (17) to the second position, and is connectable to said discharge tank (6) at the intermediate position of said main valve means (11) so as to allow the return of said control valve means (17) to the first position as a result of the action of said first elastic means (18).10) Piece of equipment (1) according to claim 8, characterized by the fact that it comprises auxiliary valve means (20) positioned between said pumping means (5) and said main valve means (11) and movable between at least one discharge position, wherein they set said pumping means (5) in communication with said discharge tank (6), and a feeding position, wherein they set said pumping means (5) in communication with said main valve means (11), on said auxiliary valve means (20) operating second elastic means (21) on one side as well as a second piloting line (22) communicating with said control valve means (17) and, on the opposite side, a third piloting line (23) communicating with said pumping means (5), said second elastic means (21) and the pressure of the fluid along said second piloting line (22) being adapted to counteract the displacement of said auxiliary valve means (20) from the feeding position towards the discharge position.11) Piece of equipment (1) according to claim 10, characterized by the fact that said second piloting line (22) is set in communication with said discharge tank(6) when said control valve means (17) are in the first position and is connectable, when said control valve means (17) are in the second position, to said first feeding line (13) in the lifting position of said main valve means (11) and to said second feeding line (14) in the descending position of said main valve means (11). 12) Piece of equipment (1) according to one or more of the preceding claims, characterized by the fact that said control lever (3, 4) comprises at least a first control lever (3) and by the fact that it comprises first mechanical means (24) for connecting said first control lever (3) to said distributor element (12).13) Piece of equipment (1) according to one or more of the preceding claims, characterized by the fact that it comprises at least one abutment element (25) operationally connected to said driving element (2), by the fact that said control lever (3, 4) comprises at least a second control lever (4), by the fact that it comprises second mechanical means (26) for connecting said second control lever (4) to said abutment element (25), and by the fact that said second mechanical means (26) are operationally connected to said first mechanical means (24).

Images