Hydraulic unit for shaking groups of harvesting machines

Abstract

The present invention is related to an improved hydraulic unit for agricultural machines that is particularly, but not exclusively, used in controlling the movement of shaking units in grape harvesting machines. This unit is characterized by a hydraulic circuit including a flow divider which, in combination with other inventive devices, overcomes the problems of known hydraulic units i.e. the pressure drop of the servo valves that occurs during the transition between the opened and closed states of the valves or when flow saturation occurs in certain grape harvesting conditions.

Description

[0001] TITLE: HYDRAULIC UNIT FOR SHAKING GROUPS OF HARVESTING MACHINES

[0002] TECHNICAL FIELD

[0003] The invention concerns components for agricultural machinery and in particular an improved hydraulic unit for controlling the movement of the shaking units.

[0004] BACKGROUND ART

[0005] The present invention is related to components for agricultural machines and particularly an improved hydraulic unit that is particularly, but not exclusively, used in controlling the movement of shaking units in grape harvesting machines.

[0006] Grape harvesting machines, also named “grape harvesters”, are agricultural machines dedicated to mechanized grape harvesting operations.

[0007] In short, a grape harvesting machine is made up of the following units: a harvesting unit to detach grapes from the plant. The unit consist of a plurality of shaking arms fixed to four shafts and organized in two opposing shaking groups; a capturing system to collect the grapes detached from the plant by the shaking groups. The system may consist of conveyor belts; a cleaning system composed of a crusher and an aspirator to cut and remove leaves and remains that have fallen during shaking; a hopper for storing the harvested grapes; a group for moving the mechanical parts of the previous units, connected to the tractor's crankshaft or engine.

[0008] Further details of this type of machine are described, for example, in patent specification US8511051 B2 in the name of Pellenc SA.

[0009] The two rear shafts of the opposing shaking groups are set in reciprocating motion by appropriate kinematic mechanisms connected to a hydraulic unit controlled by a control unit.

[0010] A known type of hydraulic unit is described in the French patent FR2768016B1 in the name of Pellenc. This unit, which for ease of presentation is illustrated in the attached Figure 1, is in summary made up of a hydraulic block (9) fed by pressurized oil via a single supply pipe. The unit includes a pressure regulation system, two hydro-pneumatic accumulators (10a, 10b) and two servo valves (12a, 12b) or proportional electro-distributors. The hydro-pneumatic accumulators (10a, 10b) provide an energy supply and compensate the pressure peaks of the system. Generally, the unit is also equipped with an inlet filter and a safety valve.

[0011] The hydraulic unit operates the hydraulic cylinders (5a, 5b) so that when one is in an open state the other is in a closed state, and these in turn impart an alternating movement to the two shaking units.

[0012] Although this hydraulic unit is a widely used solution in the field, it presents a remarkable limitation that has become more evident in recent years due to the increase in performance required to the grape harvesting machines.

[0013] In short, this limitation originates from the pressure drop that in some conditions affects the hydraulic circuit.

[0014] A first condition arises when the energy accumulated in the storage tanks (10a, 10b) is not sufficient to compensate for the physiological pressure drop in the hydraulic cylinder actuation circuit that occurs during the transition between the two states of the servo valves.

[0015] Other unfavorable conditions occur in heavy-duty flow / pressure regimes (typically 45 liters / minute at the inlet), or with large shaking arms, when an increase in the operating temperature and fluidity of the oil occurs. This leads the servo valves to a condition technically called “flow saturation”. In practice, the pressure drop across a servo valve is too high and hence the fluid flows towards the exhaust circuit and not towards the hydraulic cylinder chambers. This condition causes a drop in operating pressure that is not be compensated by the pressure accumulated in the storage tanks (10a, 10b). The main effect of the pressure drop is the incorrect and asynchronous movement of the shaking group shafts, which causes a phase shift in the movement of the arms defined in jargon as the “applause effect”.

[0016] In this condition, the efficiency of grape harvesting decreases and at the same time damages to the leaf walls of the row of vines are significantly increased. When the operator realizes that the grapes have not been harvested, is forced to lower the harvest parameters so that the machine operates in conditions that avoid saturation of the servo valves in the hydraulic unit.

[0017] These harvesting conditions are not acceptable in some wine-growing areas because they lead to a reduction in performance and therefore an increase in costs. For example, in Veneto, a well-known Italian region for wine production, the optimal speed in terms of costs / benefits is 4.5 km / h and must be lowered to 2.5 km / h.

[0018] The problem of pressure losses is due to the intrinsic characteristics of the servo valves, typically “Moog valves”, and to the fact that the hydraulic circuit of the known type of block is not of the “closed loop” type but rather “open loop” type.

[0019] It is well-known that a “closed loop” circuit includes a feedback mechanism that allows the operation of the hydraulic unit to be stabilized. Therefore, in theory, the problem stated above could be solved by transforming the circuit of the known type of hydraulic block into a closed loop circuit. For instance, the insertion of a PLC is useful to first verify which of the two valves enters saturation mode and then to adjust the hydraulic unit by anticipating or postponing the activation of the actuating valve. However, the circuit would become excessively expensive, complicated and not sufficiently robust to withstand the severe operating conditions of a typical mechanized grape harvest.

[0020] Following a careful state of the art search, at present the technical problem herein described does not appear to have been adequately addressed.

[0021] Therefore, there is a need for improving hydraulic units for shaking groups which represents a crucial component not only in grapes harvesting machines, but more generally in all those agricultural machines that include actuators with similar movements. DISCLOSURE OF INVENTION

[0022] Object of the invention

[0023] The present invention intends to overcome the limitations and drawbacks of the solutions known in the art, by providing an improved a hydraulic unit suitable for shaking groups of harvesting machines.

[0024] In particular, the main object of the present invention is to disclose a hydraulic unit for shaking groups which is configured to operate in any harvesting condition, preventing the servo valves from entering a saturated regime or any other condition that could compromise the correct movement of the shaking groups.

[0025] A second purpose of the present invention is to provide a hydraulic unit which is able to impart the correct movement of the shaking groups in any harvesting condition, avoiding the so-called "applause effect" and to ensure the maximum possible yield according to pre-set harvesting parameters.

[0026] A further important purpose of the present invention is to provide a hydraulic unit for shaking groups based on an "open loop" hydraulic circuit which has a simpler structure compared to a "closed loop" hydraulic circuit, but it is equally capable of ensuring robustness and reliability in any harvesting condition, even the most severe.

[0027] A fourth purpose of the present invention is to provide a hydraulic unit for shaking groups suitable for application on “smart” grape harvesting machines, i.e. grape harvesting machines in which suitable actuators independently manage the frequency, amplitude and distance between the groups of shaking elements.

[0028] Finally, within the scope of the present invention, a final object is to provide a hydraulic unit for shaking groups that can be made using known technologies and at low costs to facilitate its adoption on a large scale. Technical solution

[0029] These and still other purposes, which will appear more clearly hereinafter, are achieved by a hydraulic unit for shaking units whose general characteristics are defined by the enclosed claim 1 , while the features of advantageous embodiments are set forth in the corresponding dependent claims.

[0030] The object of the present invention is also achieved by a grape harvesting machine comprising said group whose general and detailed characteristics are set forth, respectively, in the enclosed claim 15 and in the corresponding dependent claims.

[0031] The aforementioned claims, to which reference is made for the sake of brevity of exposition, are specifically and concretely defined below and are intended to be an integral part of this description.

[0032] Accordingly, it is within the scope of the present invention to provide an improved hydraulic unit for use on an agricultural machine. Said group includes a main circuit comprising: a first actuator interlocked to a first servo valve supplied by a delivery pipe and having a first drain pipe; a second actuator interlocked to a second servo valve supplied by a delivery pipe and having a second drain pipe.

[0033] The hydraulic unit (1) is characterized by the fact of including a flow divider fluidly connected to the main circuit so as to receive a pressurized fluid at the inlet via a delivery pipe and split said fluid at the outlet to feed said servo valves through suitably designed pipes.

[0034] The main circuit, and hence the hydraulic unit, is fed by a hydraulic fluid circulated by a pump, of a known type, which can be fluidically connected to the main circuit or to a secondary circuit which feeds said primary circuit.

[0035] The pump makes the hydraulic fluid to flow in the circuit at a pressure and a flow rate corresponding to parameters set by means of a control unit. Furthermore, it is also within the scope of the present invention to provide a grape harvesting machine comprising one or more hydraulic units as defined above for imparting a motion to the shaking units.

[0036] In other words, the issues described in the technical field section are addressed by a hydraulic unit having a circuit comprising a flow divider which equally split the fluid on each of the two servo valves. In this way, the "sub-circuits" serving the actuators, which impart movement to the shaking units of the grape harvester, are made independent of each other and the servo valve does not absorb the pressure from the other servo valve. The result is that the flow rate and pressure of the fluid entering the actuators is the same and the movements of the two groups of shakers are perfectly synchronized i.e. with one cylinder is in an opened state and the other in a closed state (and vice versa).

[0037] Preferably the actuators of the hydraulic unit that move the shaking groups are double-rod hydraulic cylinders. Furthermore, each servo valve, of the Moog type, can be protected by means of a suitable alarm circuit and is fluidically connected to a hydraulic accumulator with pre-charge, preferably of the gas-charged accumulator.

[0038] Despite its simplicity, the hydraulic unit according to the invention does not seems to have ever been exploited in the field of grape harvesting machines.

[0039] In alternative embodiments, the hydraulic unit includes sensors in data connection with the control unit in order to monitor the operation of the hydraulic unit and to catch anomalies promptly. In particular, a first type of sensors, e.g. pressure switches, detect in real time the pressure values in the branches of the circuit and transmit such values to the control unit. The control unit, acting on the pump and on the discharge valve, varies the pressure or the flow rate of fluid in the circuit if a pressure drop occurs on the servo valves or on the actuators.

[0040] In such alternative embodiments, a second type of sensors detects the position of the stems so that the control unit can promptly catch a condition of asymmetry in the movement of the shaking units.

[0041] However, sensors in the hydraulic unit, although useful, are not essential for the present invention, since one of the main purposes is actually providing an open-loop hydraulic circuit unlike those of the known type which have a closed-loop configuration.

[0042] The features and advantages of the present invention will be more fully understood by reference to the following drawings:

[0043] Figure 1 shows the hydraulic diagram of a known-type group for shaking groups of harvesting machines;

[0044] Figure 2 is the hydraulic diagram of the group according to the preferred embodiment of the present invention;

[0045] Figure 3 is the hydraulic diagram of the group according to the second preferred embodiment of the present invention;

[0046] Figure 4 is the hydraulic diagram of the group according to the third preferred embodiment of the present invention.

[0047] These drawings illustrate and demonstrate various features and embodiments of the present invention but are not to be construed as limiting the invention.

[0048] DETAILED DESCRIPTION OF THE INVENTION

[0049] The reduction to practice of the inventive concept is provided by the following four preferred, but not exclusive embodiments, the detailed explanation of which is reported below.

[0050] First preferred embodiment

[0051] In the first preferred embodiment, herein described by way of example and not limitation with reference to the enclosed Figure 2, the hydraulic unit according to the present invention is generally designated by the reference number (1).

[0052] In such embodiment, the unit (1) has a hydraulic circuit that can be divided into two parts: a main circuit (10) and a secondary circuit (20).

[0053] The main circuit (10) includes a flow divider (11) that splits the incoming fluid into two equal parts so as to feed two identical servo valves (12a, 12b), each being served by an actuator (13a, 13b).

[0054] In the first embodiment, the flow divider (11) is preferably a flow divider with a single-valve flow divider i.e. a flow divider with a single phase-correction valve. However, equivalent components can be usefully used e.g. a multiple-valve flow divider, a flow divider with anticavitation valves, an auto-compensating flow divider, or a combination thereof.

[0055] In this embodiment, the servo valves (12a, 12b) are Moog valves with a 4 / 3-way design and are actuated by angular sensors in data connection with said control unit. The sensors are positioned on the rear uprights of the grape harvester. Furthermore, the servo valves (12a, 12b) are fed by delivery ducts (P1 ,P2), respectively, and share the same discharge duct which is indicated with (T1) in the enclosed Figure 2.

[0056] Preferably the two actuators (13a, 13b) are identical double-rod hydraulic cylinders. However, provided they are compatible with the intended use, other types of actuators can be used e.g.: double-acting hydraulic cylinders without through rod, hydraulic linear motors, hydraulic linear servomotors.

[0057] Each of the cylinder stems is mechanically connected to a shaking group of the grape harvesting machine, preferably a mechatronic or “smart” grape harvesting machine.

[0058] In the first preferred embodiment, the hydraulic unit (1) comprises two identical hydraulic accumulators (14a, 14b) with pre-charge, each being served by the corresponding actuator (13a, 13b) and fluidically connected to the delivery duct of the corresponding servo valve (12a, 12b).

[0059] As in known hydraulic assemblies, the hydraulic accumulators (14a, 14b) absorb fluid hammer during the circuit start-up phase and manage the pressure drop that intrinsically occurs during transients in servo valves (12a, 12b) i.e. when the valves open or close. Typically, each accumulator (14a, 14b) has a volume of 0.75 cm3and a gas pre-charge which can manage pressure fluctuations up to 95 bar.

[0060] As schematically illustrated in Figure 2, the components described above are hydraulically connected to each other via hydraulic connections (16) which include: two delivery ducts (P1 ,P2) to the two servo valves (12a, 12b); an exhaust duct (T1) common to the two servo valves (12a, 12b); connection ducts (B11 , A11) of the first servo valve (12a) to the two chambers of the first actuator (13a); connection ducts (B21 , A21) of the second servo valve (12b) to the two chambers of the second actuator (13b). Clearly the two hydraulic accumulators (14a, 14b) are hydraulically connected to the respective delivery ducts (P1 ,P2) to the two servo valves (12a, 12b).

[0061] In practice, the main circuit (10) is divided into two identical subcircuits, each being served by one of the actuators (13a, 13b). The two subcircuits are hydraulically connected so that the rods of the cylinders (13a, 13b) move synchronously and out of phase with each other from right to left (and vice versa). Therefore, when the rod of the first cylinder (13a) comes out to the right, the rod of the second cylinder (13b) comes back in to the right, i.e. with a ri ght- 1 eft / l eft- right movement.

[0062] Thanks to the flow divider (11), the two subcircuits are independent of each other even if they are hydraulically connected.

[0063] From the description provided, it shall be apparent to those skilled in the art that the main circuit (10) is of the open loop type. In this way, a main purpose of the present invention has been achieved.

[0064] In the first embodiment of the present invention, herein provided by way of example and not limitation, the hydraulic circuit of the unit (1) includes a secondary circuit (20) having a safety valve (21) and a filter (22) equipped with a pressure control system. With reference to the unit Figure 2, the components (21 ,22) are hydraulically connected to each other via hydraulic connections (24) which include: a delivery duct (P0) to the flow divider (11); a discharge duct of the flow divider (11); a delivery duct (P) to the secondary circuit (20) and a discharge duct (T) of the secondary circuit (20).

[0065] In the first embodiment, the discharge ducts (T0,T1) are two and are hydraulically connected by, for example, a rigid pipe.

[0066] Optionally, the pressure inside the secondary circuit (20) is controlled by a suitable sensor, preferably a pressure switch (23) in connection with the control unit (not shown) which blocks the hydraulic unit (1) in the event of an alarm condition.

[0067] In this embodiment, by calibrating the safety valve (21) to 130 bar, it is possible to manage overpressures in all operating conditions of the grape harvester.

[0068] From the description provided it will be evident to those skilled in the art that the secondary circuit (20) is fluidically connected to the primary circuit (10) so that the ducts (P,T) are the delivery duct and the discharge duct of the entire circuit (10,20) of the hydraulic unit (1) according to the first embodiment of the invention. In turn these ducts (P,T) are hydraulically connected to a pump (not shown) of a known type which is driven by the tractor shaft, in the case of a towed grape harvester, or alternatively by an autonomous motor, for example an electric motor of suitable power according to the needs of the pump.

[0069] The pump makes the hydraulic fluid to flow into the circuit (after proper filtration) at the pressure and flow rate defined according to the harvest parameters set by means of the control unit.

[0070] The delivery duct (P0) exiting the secondary circuit (20) feeds the flow divider (11), and hence the circuit (10), while the discharge duct (TO) of the flow divider valve (11) is hydraulically connected to the discharge ducts (T0,T1) common to the two servo valves (12a, 12b) and to the discharge (T).

[0071] From the description provided it shall be apparent that the development of the hydraulic unit according to the invention, despite its apparent simplicity, involved to overcome challenging technical problems for those skilled in the art, particularly with reference to the design of the pipe sections and therefore of the operating pressures and calibrations of the system.

[0072] In fact, the identification of the optimal operating pressures is the result of a balance between conflicting technical requirements. Particularly, the maximum pressure of the system is directly related to the shaking force imparted to the plant. A pressure value excessively low does not allow an efficient harvest of fruit, but on the contrary a pressure too high causes damage to the plant. Therefore, the definition of the pressure is the result of both on-field testing and inventive activity.

[0073] Second preferred embodiment

[0074] The second preferred embodiment, described here by way of example and not limitation, refers to a hydraulic unit having substantially the same circuit as the first embodiment, and being characterized by the fact of further including two pressure switches (15a, 15b). Each of the pressure switches (15a, 15b) is inserted in the sub-circuits comprising the servo valves (12a, 12b) and are connected to a control unit (not shown) that manages the different conditions of use and anomalies according to the pressure values detected within each sub-circuit.

[0075] Third preferred embodiment

[0076] The third preferred embodiment, described here by way of example and not limitation, refers to the hydraulic unit shown in the enclosed Figure 4. Said unit has a circuit similar to those of the first or second embodiment, with the exception of the two hydraulic accumulators with precharge (14a, 14b) which are not present in this embodiment. In this way, a further constructive simplification of the hydraulic unit according to the invention is obtained.

[0077] Other technical details for implementing this embodiment may be derived from the previous one or from common general knowledge of the skilled in the art. Fourth preferred embodiment

[0078] The fourth preferred embodiment, herein provided by way of example and not limitation, refers to a hydraulic unit having the same circuit as the two previous embodiments and which further comprises a compensation device which is intended to restore synchronization of the actuators movement if an asymmetry is determined in the amplitude or frequency of the movement of the first actuator (13a) with respect to the second actuator (13b).

[0079] As previously stated, in the first embodiment the two control sub-circuits of the actuators (13a, 13b) are identical in order to ensure an alternating synchronous movement, in phase or out of phase, of said actuators. However, conditions leading over time to asymmetries in the movement of one shaking units may occur e.g. due to tolerances in the manufacturing of the actuators, asymmetries in the actuators, or unpredictable conditions of use.

[0080] Other technical details for implementing this embodiment may be derived from the previous one or from common general knowledge of the skilled in the art.

[0081] CONCLUSIONS

[0082] To conclude, it has been shown that the invention described hereinabove fully achieves the intended aim and objects. In particular, it will be evident to those skilled in the art that the hydraulic unit for shaking groups is novel and has been achieved through a non-trivial inventive effort in particular to define the correct operating pressures and calibrations of the group.

[0083] The invention is not limited to the exemplary embodiments shown and described herein and although the description and examples provided contain many details, these should not be construed as limiting the scope of the invention but simply as illustrations of some embodiments of the present invention.

[0084] For example, the flow divider can split the incoming fluid into different parts, and not necessarily into two equal parts, in those applications in which the actuators are not required to move in the same way. Furthermore, the cylinder rods could move following an out of phase synchronous motion i.e. with right-left / left-right movement (or vice versa).

[0085] Hence, any modification of the present invention which falls within the scope of the following claims is considered to be part of the present invention.

[0086] Where the characteristics and techniques mentioned in any claim are followed by reference signs, these reference marks have been applied solely for the purpose of increasing the intelligibility of the claims and consequently these reference marks have no limiting effect on the interpretation of each element identified by way of example from these reference signs.

Claims

CLAIMSWhat is claimed:1) Hydraulic unit (1) for use on an agricultural machine, said unit having a main circuit (10) comprising: a first actuator (13a) interlocked to a first servo valve (12a) supplied by a delivery pipe (P1) and having a first drain pipe (T1), said first actuator (13a) having two chambers fluidly connected to the first servo valve (12a) via connection pipes (B11.A11); a second actuator (13b) interlocked to a second servo valve (12b) supplied by a delivery pipe (P2) and having a second drain pipe (T2), said second actuator (13b) having two chambers fluidly connected to the second servo valve (12b) via connection pipes (B21.A21); optionally, a pump fluidly connected to the main circuit (10), to cause the flow of a hydraulic fluid inside the pipes (P1 ,P2,T1 ,T2,B11 ,A11 ,B21 ,A21), said hydraulic unit (1) being characterized by the fact of including a flow divider (11) fluidly connected to the main circuit (10) so as to receive a pressurized fluid at the inlet via a delivery pipe (P0) and split said fluid at the outlet to feed said servo valves (12a, 12b) through said pipes (P1 ,P2).2) Hydraulic unit (1) according to claim 1 wherein the primary circuit (10) is interlocked to a control unit and in association with said control unit constitutes an open loop control system.3) Hydraulic unit (1) according to claim 1 or 2 wherein the flow divider (11) is of the type selected from: a flow divider without valves, a single-valve flow divider, a multiple-valve flow divider, a flow divider with anti-cavitation valves, an auto-compensating flow divider, or a combination thereof.4) Hydraulic unit (1) according to one or more of the previous claims wherein: the flow divider (11) splits the incoming fluid into two equal flows; the two servo valves (12a, 12b) are identical to each other; the two actuators (13a, 13b) are identical to each other; the first drain pipe (T 1) and the second drain pipe (T2) are the same.5) Hydraulic unit (1) according to claim 1 or 2 or 3 wherein the two actuators (13a, 13b) are: double-rod hydraulic cylinders, double-acting hydraulic cylinders, linear hydraulic motors, or a combination thereof.6) Hydraulic unit (1) according to one or more of the previous claims wherein the first and second servo valves (12a, 12b) are fluidly connected in such a way that: the first actuator (13a) and the second actuator (13b) exhibit in-phase synchronous motion, i.e. right-right / left-left; or the first actuator (13a) and the second actuator (13b) exhibit anti-phase synchronous motion, i.e. right-left / left-right.7) Hydraulic unit (1) according to one or more of the previous claims wherein the primary circuit (10) includes hydraulic accumulators (14a, 14b) each being interlocked to the corresponding actuator (13a, 13b) and is fluidly connected to the delivery pipe delivery of the corresponding servo valve (12a, 12b).8) Hydraulic unit (1) according to one or more of the previous claims wherein the primary circuit (10) includes one or more sensors for detecting the pressure in the main circuit (10), preferably two pressure switches (15a, 15b) for pressure detection, respectively, in the connection pipes (B11 ,A11) and in the connection pipes (B21.A21).9) Hydraulic unit (1 ) according to one or more of the previous claims which further includes a secondary circuit (20) fluidly connected to said primary circuit (10) through a delivery pipe (P0) and an drain pipe (TO), said secondary circuit (20) comprising:a filter (22) fluidly connected to the secondary circuit (20); one or more sensors for detecting the pressure in the secondary circuit (20), preferably a pressure switch (23) connected to said control unit; a pump fluidly connected to a delivery pipe (P) and to an drain pipe (T) to cause a flow of a hydraulic fluid through said primary circuit (10) and in said secondary circuit (20); optionally, an alarm circuit fluidly connected to the secondary circuit (20) and having at least one safety valve (21), said alarm circuit which in association with the control unit is configured to stop the hydraulic unit (1) in the event that an alarm condition occurs, said secondary circuit (20) wherein the delivery pipe (P0) supplies the flow divider (11) and the drain pipe (TO) of the flow divider (11) is hydraulically connected to the drain pipe (T1) which is shared by the two servo valves (12a, 12b) and by the drain pipe (T).10) Hydraulic unit (1 ) according to one or more of the previous claims which further includes a compensation device configured to ensure, in association with said control unit, that the motion of the first actuator (13a) has the same amplitude and frequency of the movement of the second actuator (13b).11) Hydraulic unit (1) according to one or more of the previous claims wherein said one or more sensors, said pump, said alarm circuit and said compensation device are managed by said control unit.12) Hydraulic unit (1) according to one or more of the previous claims wherein each of the actuators (13a, 13b) is mechanically connected to a shaking unit of a grape harvesting machine.13) Hydraulic unit (1) according to claim 12 wherein said machine is a mechatronic grape harvesting machine or a "smart' grape harvesting machine.14) Hydraulic unit (1) according to one or more of the previous claims wherein the first and the second servo valve (12a, 12b) are of the 4 / 3 type and are actuated by angular sensors connected to said control unit.15) Harvesting machine comprising at least one hydraulic unit (1) according to one or more of claims 1 to 14 for use in actuation means of shaking units.16) Grape harvesting machine comprising at least one hydraulic unit (1) according to claim 14 characterized in that said angular sensors are placed on the rear uprights of the grape harvester.

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