Safety system of working machine

Abstract

Described is a self-propelled working machine (1) provided with a mechanism (10) for moving a load and equipped with a safety system designed to prevent the risk of instability and comprising means (3) for detecting the position and weight of the load and further comprising a processing unit (2), the processing unit is connected to the detection means (3) and in turn comprises: a checking module (21) configured to compare the weight of the load with a reference value selected based on the position of the load; and a limiting module (22) configured to generate a limiting signal adapted to limit the movement of the moving mechanism (10) after the comparison by the checking module. The reference value is independent of the angular position of the movement mechanism (10).

Description

Technical Field

[0001] The present invention relates to an improved safety system for a self-propelled working machine.

[0002] In more detail, the present invention particularly (but not exclusively) relates to a telehandler. Background Art

[0003] There are prior art telehandlers which consist of a vehicle provided with a chassis movable by wheels, a cab accommodating the operator, and a maneuvering boom which can be extended for lifting and lowering a load.

[0004] In some models the maneuvering boom is articulated directly to the chassis, while other models provide a platform or "turret" rotatably mounted on the chassis, with the cab provided on it and the maneuvering boom articulated to it.

[0005] Attached to the distal end of the arm is a device for lifting or moving the load, such as a fork, platform, winch, etc.

[0006] Telehandlers are known to be equipped with a system for limiting the longitudinal moment, which monitors the variable geometrical parameters of the machine (sliding length of the arm, lifting angle of the arm relative to the horizontal, etc.), instantly calculates the maximum permissible load and determines whether there is a risk of instability.

[0007] In fact, under certain stability conditions, depending on the position of the load carried by the arm and its weight, it can be determined whether the machine is at risk of tipping over. If the working conditions are close to those where there would be a risk of instability, maneuvering the boom towards a deteriorating position of the load is automatically prevented to prevent the above risk.

[0008] There are various types of systems on the market for limiting longitudinal moments, some use load sensors on the rear axle of the machine, others use different sensors and may impose different rules on the movements allowed or prevented for maneuvering the boom. Summary of the invention

[0009] The technical purpose forming the basis of the present invention is to propose a self-propelled working machine equipped with a safety system against instabilities which is different from and an alternative to the systems currently on the market for limiting longitudinal moments. The technical purpose also relates to a method of operating a self-propelled working machine.

[0010] This specific technical object is achieved by the present invention made according to the appended claims. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Other characteristics and advantages of the invention become more apparent in the non-limiting description of a preferred embodiment of the proposed machine as shown in the accompanying drawings, in which:

[0012] - Figure 1 is a side view of a working machine according to the present invention;

[0013] - Figure 2 is a diagram showing a safety system according to the present invention;

[0014] - Figure 3 is the load diagram of the proposed machine. DETAILED DESCRIPTION

[0015] With reference to the accompanying drawings, reference numeral 1 denotes as a whole a self-propelled working machine made in accordance with the present invention.

[0016] The machine 1 shown in the figures is a telehandler of the so-called "fixed" type, equipped with a telescopic lifting boom 10 directly articulated to a chassis 11, movable by wheels, housing a cab 12. Furthermore, the boom 10 is equipped with an attachment 13 at its distal end.

[0017] Optionally, the frame 11 may also be equipped with an outrigger comprising a plurality of stabilizing arms; for example, the machine 1 may be equipped with a so-called “scissor-like” outrigger.

[0018] According to some embodiments, tracks or other motion devices may be used in place of wheels.

[0019] The machine 1 may be provided with any propulsion system, in particular an internal combustion engine, an electric power system or a hybrid power system.

[0020] The term attachment 13 refers both to devices for engaging the load, such as forks, arms equipped with hooks, winches, clamps, etc., and to devices for lifting persons and, if necessary, the load, such as loading platforms.

[0021] In still more detail, the boom 10 may have, at its distal end, coupling means, also of the type commonly used in telehandlers manufactured by the Applicant, which allow the attachment 13 to be replaced and connected to the hydraulic and electronic equipment of the machine 1 .

[0022] The boom 10 is articulated to swing vertically between a lower position (substantially horizontal) and an upper position (in which the boom 10 is close to vertical) under the action of a hydraulic cylinder 14 or similar actuator. Optionally, the machine 1 may include two lifting cylinders 14 or similar actuators. Figure 1 Also shown is a compensation cylinder 15 which is hydraulically connected to an actuator for adjusting the alignment of the attachment 13 .

[0023] The boom 10 is extendable and retractable and more precisely comprises a plurality of sectors coaxial with one another and inserted one inside the other and designed to translate in the axial direction.

[0024] The extension and retraction of the boom 10 is also performed by one or more hydraulic cylinders 16 (see Figure 2 ) or other actuators, or also by telescopic cylinders (or other actuators with multiple stages).

[0025] The machine 1 also comprises an electro-hydraulic distributor 17 to which the hydraulic actuators used in the machine 1 are individually connected according to known methods. The distributors are supplied by pumps actuated by an electric motor situated on the machine 1. However, embodiments of the invention are not excluded in which one or more of the above-mentioned actuators are of the electric type instead of the hydraulic type.

[0026] However, it should be noted that the present invention can be used with different types of working machines, which are generally provided with a mechanism 10 for moving a load.

[0027] In particular, the proposed machine 1 can also be a "rotating" telehandler, ie a forklift equipped with a rotating turret, which has been mentioned during the discussion of the prior art. To simplify the description, reference will be made hereinafter mainly to the example where the proposed machine 1 is a telehandler of the fixed type.

[0028] The machine 1 comprises a processing unit 2 designed to transmit control signals to a distributor according to instructions issued by an operator sitting in the cab, which distributor thus controls actuators so that the actuators operate the boom 10, the frame, the drive engine and the attachment 13, as well as other devices included in the machine 1.

[0029] In practice, the machine 1 comprises control means available to the operator in the associated cab 12, such as joysticks, pedals, buttons, etc.; when the operator acts on these control means, the processing unit generates control signals received by the distributor which then regulates the operation of each actuator of the boom 10, the bracket, the attachment 13, etc. accordingly.

[0030] Furthermore, if necessary, the invention may include the use of a remote control comprising control means corresponding in functionality to those present in cab 12 and designed to transmit control signals to a receiver connected to the processing unit.

[0031] In practice, the processing unit 2 transmits control signals to the distributor which then commands the actuators according to certain conditions.

[0032] The machine 1 according to the invention is equipped with a safety system capable of preventing risks of instability; moreover, optionally, the safety system may also be capable of preventing risks of structural yielding of the maneuvering boom 10. The safety system according to the invention is designed to avoid, based on the working conditions, aggravating movements of the maneuvering boom 10 which could generate structural risks and, if necessary, risks of instability.

[0033] The safety system comprises a device 3 for detecting the position and weight of the load and also comprises an electronic processing unit 2 (in Figure 2 ), the electronic processing unit is connected to the detection device 3 and further comprises: a checking module 21, configured to compare the weight of the load with a predetermined reference value selected based on the position of the load; and a limiting module 22, configured to generate at least one limiting signal suitable for limiting the movement of the moving mechanism 10 of the machine 1 after comparison by the checking module.

[0034] According to an important aspect of the invention, the above-mentioned reference value is variable according to the position of the load, but is independent of the angular position of the moving mechanism.

[0035] Generally speaking, it should be noted that in this specification, the processing unit 2 is presented as being subdivided into a plurality of independent functional modules, which is only for the purpose of describing the functions clearly and completely.

[0036] In practice, the processing unit 2 may comprise a single electronic device, also of the type commonly present on machines of this type, such as a control unit, suitably programmed to carry out the functions described; the various modules being able to correspond to hardware units and / or software forming part of the programmed device.

[0037] Alternatively or additionally, these functions can be performed by multiple electronic devices, and the above-mentioned functional modules can be distributed on these electronic devices.

[0038] Generally speaking, the processing unit 2 may have one or more microprocessors or microcontrollers for executing instructions contained in the memory module, and the above functional modules may also be distributed on multiple local or remote computers based on the network architecture that accommodates them.

[0039] As already explained, in particular according to an embodiment of the invention in which the machine is a telehandler 1, for example, the above-mentioned moving mechanism comprises a manipulating boom 10 which can be raised and lowered under the actuation of a first actuator 14; the above-mentioned lifting cylinder can be extended and retracted under the actuation of a second actuator 16 (for example a lifting cylinder). In this case, the operation of the first actuator 14 and the second actuator 16 is affected by a limit signal generated by the processing unit 2.

[0040] In more detail, if the first actuator 14 and the second actuator 16 are of the hydraulic type, the machine comprises a hydraulic distributor 17 which may be designed to regulate the operation of the two hydraulic actuators 14 , 16 after receiving a limiting signal from the processing unit 2 .

[0041] Preferably, the aforementioned predetermined reference value is a threshold value and the limiting module 22 is configured to limit the movement of the boom 10 towards a position of deterioration of the longitudinal moment of the machine 1 if the measured weight corresponds to the threshold value, in order to avoid a situation where a risk of overturning may occur.

[0042] The term "deteriorated position" means that in this position the tipping moment, in particular the longitudinal moment of the machine 1, is increased compared to the previous position adopted by the load. A greater extension of the boom 10 or a lowering of the boom 10 may increase the moment in the indicated direction.

[0043] As is known, the longitudinal moment of the machine can be defined relative to an ideal axis of rotation which passes through the front wheels or, if present, through the front carrier.

[0044] Preferably, the limiting module 22 is configured to generate a limiting signal and is designed to prevent the boom 10 from moving the load to a deteriorating position after verifying that the weight has reached a threshold value, it being noted that this threshold value varies according to the position of the load, but not relative to the angular position of the boom 10.

[0045] In other words, the threshold value varies as a function of the linear distance of the load relative to a predetermined reference, for example along a horizontal plane or in any case a plane parallel to the ground. To this end, as described in more detail below, the stop of the movement of the boom 10 generated by the processing unit 2 is "vertical", ie it is defined on a vertical plane in space so that the load cannot exceed this vertical plane. In more detail, the above-mentioned distance may be the projection along a horizontal plane of the distance between the position of the load and the position of the hinge 18 joining the boom 10 to the frame 11.

[0046] In practice, different or equal thresholds are defined for a plurality of different positions that the load can adopt in space when being moved by the boom 10. In this way, a vector or matrix of thresholds to be compared with the weight is defined. For this purpose, the thresholds are preferably weight values.

[0047] When the weight corresponding to the threshold reaches the position associated with the threshold, the load remains stationary even if the operator acts on the control device to lower or move the load away by rotating or extending the boom 10 downward. The operator can only raise the boom 10 or reduce its extension. On the other hand, if the weight of the load is less than the threshold, the limiting module does not issue a limiting signal and therefore does not automatically prevent the movement of the boom 10.

[0048] Stopping the movement of the boom 10 towards the deteriorated position is one type of limiting the movement of the preferred boom 10, but other types of movement limitations may also be applied. In other words, the term "limitation of movement" of the operating boom 10 (more generally the movement mechanism), preferably but not exclusively refers to preventing its movement in a given direction.

[0049] In practice, the processing unit 2 may include a storage module 23 in which reference values ​​of the weight of the load are recorded, to define the above-mentioned matrix (or vector), which reference values ​​are the same or different for the different positions that the load can adopt in space. The detection device 3 allows the weight of the load being lifted to be measured and its position to be detected instantaneously. Based on the detected instantaneous position, the checking module 21 compares the weight of the load with the reference weight and, if they are equal, the limiting module 22 emits a limiting signal which affects the movement of the boom 10 in a limiting manner.

[0050] The prevention of movement of the boom 10 actuated by the safety system is referred to as a movement "cut-off" or "stop." In addition to stops, other types of movement restrictions are possible.

[0051] The detection device may include one or more of the following components: a pressure sensor 31 of the hydraulic lifting cylinder 14 of the boom 10, a length sensor 32 for determining the instantaneous length of the boom 10, and an angle sensor 33 for detecting the angular position of the boom 10 (see Figure 2 ). In more detail, the lifting cylinder 14 can be equipped with two sensors 31 detecting the pressure, one sensor being located at the base and the other being located at the piston. If there are two lifting cylinders 14, each lifting cylinder can have two sensors 31 positioned in the manner described. The length sensor 31 can be a cable winding sensor, which can also be combined with an angle sensor 33.

[0052] Additionally or alternatively, there can also be sensors applied to the rear axle of the machine which directly or indirectly detect the reduction in load, such as load cells or strain gauges.

[0053] Furthermore, if the machine 1 is equipped with a stand, the processing unit 2 can also be configured to limit the movement of the mobile mechanism 10 also based on the information that the stand is placed on the ground and, if necessary, also based on, for example, the position of the stand (if it is retractable) relative to the extension degree. In this case, sensors will be provided to detect these situations.

[0054] The processing unit 2 may include a calculation module 24 configured to calculate the weight and position of the load based on the parameters obtained from the detection device. In more detail, the memory module 23 may contain information related to the weight and position of the center of gravity of the boom 10 and the attachment mounted at the end of the boom. In this case, based on the parameters related to the boom 10 and the attachment 13 included in the memory module, the calculation module 24 is configured to determine the reaction force vector of the lifting cylinder 14 based on the measurement of the pressure sensor 31 and thus calculate the weight of the load.

[0055] The computing module 24 may be configured to determine the position of the load (relative to a predetermined reference, such as a hinge between the boom 10 and the frame 11 ) based on the signals generated by the length sensor 32 and the angle sensor 33 .

[0056] Safety systems can also be designed to ensure the structural safety of the machine.

[0057] In this case, the machine 1 is configured such that the force applied by at least one of the actuators 14, 16 for actuating the maneuvering boom 10 is limited by a predetermined maximum threshold.

[0058] Thus, the machine 1 is designed so that the load-moving force applied by manipulating the boom 10 (or other load-moving mechanism) is limited by a maximum threshold, at least for some movements.

[0059] More specifically, in order to maintain the structural safety of the boom 10, only the actuator 16 used for the extension of the boom 10 may be limited by the above-mentioned forces. In fact, in this case, the boom 10 can exert a predetermined maximum thrust on the load, and therefore, the maximum extension of the boom will be constrained by this limit and will depend on the weight of the load carried; in other words, under conditions of equal load, it will be possible to make the maximum operating length of the boom 10 less than the maximum geometric length, that is, the maximum geometric length is the length obtained after each section constituting the boom 10 is fully extended. In other words, the maximum threshold is selected in a way that allows or prevents the boom 10 from reaching a certain length depending on the weight of the load.

[0060] This function can be achieved by limiting the operating pressure of the cylinder to a predetermined maximum threshold.

[0061] In particular, this can be achieved by configuring the hydraulic circuit including the sliding cylinder 16 of the boom 10 such that the hydraulic circuit is supplied with working fluid and the pressure of the working fluid is limited by a maximum value corresponding to the above-mentioned predetermined maximum threshold value.

[0062] In more detail, the circuit also includes the above-mentioned distributor 17, which can be designed to supply working fluid to the cylinder, and the pressure of the working fluid is limited by a maximum pressure value, which is lower than the maximum value of the pressure that enables the cylinder 16 to work.

[0063] For example, a maximum internal pressure valve of the circuit, located inside the distributor, may be calibrated to define the maximum pressure value of the fluid supplied to the extension cylinder 16 .

[0064] It should also be noted that if two or more hydraulic cylinders 16 (or, in general, two extension actuators) are provided, then regardless of how they are manufactured, the pressure (or, in any case, thrust) limit of one of them may be equal to or even different from the pressure limit of the other. Similarly, in the case of a telescopic cylinder with multiple stages, or in any case of an actuator with multiple stages, each stage may have a different thrust threshold, for example a different maximum pressure.

[0065] Embodiments are also possible in which the pressure limitation is achieved by calibrating or configuring other parts of the hydraulic circuit, such as the extension cylinder 16 or a suitable valve, to obtain the above-mentioned maximum threshold.

[0066] Thanks to this advantageous feature, the risk of structural yielding of the boom 10 can be avoided, since the stresses on the boom 10 depend on the weight of the load and on the extension of the arm, i.e. on the length of the boom 10 itself, which in practice corresponds to the distance between the load and the hinge connecting the boom 10 to the frame 11 (or other reference).

[0067] Thus, since the thrust of the extension cylinder 16 is limited in the manner explained above, the maximum permissible extension of the boom 10 can be reduced proportionally with increasing load weight. This prevents the mechanical stresses on the boom 10 from becoming a hazard to its structural resistance.

[0068] Indeed, after reaching the predetermined pressure limit, even if the operator acts on the control device to continue extending the boom 10, the boom cannot be extended further and the load remains stationary; in this case, the operator can retract the boom 10 but cannot extend it further.

[0069] If the load being moved is limited, the maximum force that can be applied by the boom 10 in push mode may also allow the boom to be extended to its maximum possible or "geometric" length, i.e. the designed length. In the case of greater weights, the limitation on the pushing force may reduce the achievable length to a maximum operating length that is less than the maximum possible length.

[0070] It should be noted that the maximum threshold value of the load-moving force is predetermined and defined at the design level of the machine 1 .

[0071] It should be noted that this result can be obtained automatically even without the use of sensors and electronic control means; however, sensors connected to the processing unit can also be used for finer adjustments or for checking actual operating conditions or as feedback.

[0072] Thanks to this feature, the invention allows to offer on the market a telehandler that strikes a good balance between performance and cost, without risking structural safety. In fact, as will be shown below, while explaining the possible operation of the invention, when using a machine 1 of this type, operating conditions may arise in which there is no risk of tipping over, but the stresses on the boom 10 may be excessive. In these cases, the system for limiting the longitudinal moments does not automatically prevent aggravated movements of the boom 10; however, this type of machine 1 is also safe from a structural point of view, thanks to the above-mentioned force constraints applied to the maneuvering boom 10.

[0073] The following text uses Figure 3 Describe the possible operation of the present invention, Figure 3 An example of a load diagram defined by the safety system of the machine 1 is shown.

[0074] As is known, the load diagram of a telehandler defines defined areas of space around the machine 1 within which movement of the load by maneuvering the boom 10 is safe without risk of instability. The definition of these areas is determined based on the weight of the load.

[0075] exist Figure 3 In the example of , the diagram comprises a first zone Z1 delimited by the perimeters P, Q, R, T1, in which the processing unit 2 ensures that the anti-instability limitation function of the safety system does not intervene. In fact, the first zone Z1 comprises the positions adopted by the load when the boom 10 moves towards the vertical direction, that is, the positions adopted under conditions of low risk to longitudinal stability.

[0076] However, in the first zone Z1 , the “hydraulic stop” of the safety system, ie the function for limiting the thrust of the boom 10 described above, intervenes.

[0077] In fact, since the limitation of the longitudinal moment does not intervene in the first zone Z1 (except, as will be seen, at line T1), even in the case of significant loads, the extension of the boom 10 is not automatically limited by the processing unit 2. However, thanks to the advantageous feature of limiting the thrust of the boom 10 in the manner described above, an excessive extension of the boom 10 is completely prevented, which could cause stresses in it that could be dangerous for its integrity.

[0078] The second zone Z2 is defined by a first "vertical stop". The movement of the boom 10 is prevented when a load of a certain weight (1200 kg in this example) reaches the first stop line T1, which corresponds to a reference value associated with the linear distance of the above-mentioned load, which reference value is recorded in the above-mentioned memory module 23. For example, the distance considered can be the distance between the hinge 18 of the boom 10 and the first stop line T1, but it is also possible to adopt a reference point for calculating the position of the stop lines T1, T2, T3, ... In practice, the operator is not allowed to move a load with a weight in the second zone Z2.

[0079] The same logic also applies to the other zones Z2, Z3, Z4, ... which can only be reached by crossing further stop lines T2, T3, T4 with progressively lighter loads.

[0080] The invention also relates to a method of operating a working machine 1 , which may be configured as described above, including one or more optional aspects thereof.

[0081] The method comprises the following steps:

[0082] -Detect the position and weight of the load;

[0083] - comparing the weight of the load with a preset reference value selected based on the position of the load, independent of the angular position of the moving mechanism;

[0084] - limiting the movement of the mechanism 10 based on the comparison performed.

[0085] The method may include limiting movement of the moving mechanism 10 toward a position where the longitudinal moment of the loaded machine increases.

[0086] Furthermore, the method may also comprise constraining the force applied by the moving mechanism 10 for moving the load to a predetermined maximum threshold value. In this way, the "hydraulic stop" described above is obtained. In the case of a telehandler, if the machine 1 is equipped with an extendable and retractable maneuvering boom 10, the force for the extension of the boom 10 may then be limited by a predetermined maximum threshold value. Preferably, a hydraulic cylinder 16 may be provided for the extension and retraction of the boom 10; in this case, a predetermined maximum threshold value is set at the working pressure of the cylinder 16 to define the maximum longitudinal operating extension allowed for the boom 10 as a function of the load.

[0087] The proposed method may comprise further steps corresponding to respective functions performed by the machine 1 according to the invention shown in this description and comprising providing means or components of the machine 1 .

Claims

1. A self-propelled working machine (1) provided with a mechanism (10) for moving a load and equipped with a safety system designed to prevent the risk of instability, and comprising means (3) for detecting the position and weight of the load, and further comprising a processing unit (2) connected to the detection means (3) and further comprising: a checking module (21) configured to compare the weight of the load with a reference value selected based on the position of the load; and a limiting module (22) configured to generate at least one limiting signal suitable for limiting the movement of the moving mechanism (10) after the comparison by the checking module; the reference value being independent of the angular position of the moving mechanism (10).

2. A machine according to the preceding claim, wherein: The signal generated by the limiting module (22) is configured to limit movement of the moving mechanism (10) toward a position of the load that increases a longitudinal moment of the machine.

3. Machine according to the preceding claim, wherein: The moving mechanism (10) includes a manipulating boom which can be raised and lowered under the actuation of a first actuator (14) and can be extended and retracted under the actuation of a second actuator (16), the operations of the first actuator and the second actuator being affected by the limit signal.

4. Machine (1) according to the preceding claim, wherein: The first and second actuators (14, 16) are of hydraulic type, the machine (1) comprising a hydraulic distributor (17) designed to regulate the operation of the two hydraulic actuators and also designed to limit the actuation of the actuators after receiving the limiting signal from the processing unit (2).

5. A machine according to any one of the preceding claims, wherein: The processing unit (2) comprises a storage module (23) in which reference values ​​of the weight of the load corresponding to various positions that the load can adopt in space are recorded.

6. The machine (1) according to any one of the preceding claims, comprising at least one activation actuator (14, 16), wherein: The force applied by the actuator (14, 16) is constrained by a predetermined maximum threshold.

7. The machine (1) according to claim 2 and the preceding claims, wherein: The manipulator boom (10) is extendable and retractable, and the actuator (16) is adapted to actuate extension and retraction of the arm (10).

8. Machine (1) according to the preceding claim, wherein: The actuator is a hydraulic cylinder (16) whose thrust is constrained by a predetermined maximum pressure threshold to define the maximum longitudinal operational extension allowed for the arm (10) according to the load.

9. Machine (1) according to the preceding claim, comprising a hydraulic circuit including the cylinder (16), the circuit being configured to supply the cylinder (16) with a working fluid, the pressure of which is constrained to a maximum value corresponding to the predetermined maximum threshold.

10. Machine (1) according to the preceding claim, wherein: The hydraulic circuit comprises a hydraulic distributor (17) which is designed to supply a working fluid to the cylinder (16), the pressure of the working fluid being limited by the maximum value.

11. A method for operating a working machine (1), the working machine being provided with a mechanism (10) for moving a load, the method comprising the following steps: detecting the position and weight of the load; comparing the weight of the load with a reference value selected based on the position of the load, the reference value being independent of the angular position of the moving mechanism (10); as well as Movement of the mechanism (10) is restricted or freely allowed based on the comparison made.

12. The method according to the preceding claim, wherein: The movement of the moving mechanism (10) is restricted towards a position of the load that increases the longitudinal moment of the machine.

13. The method according to claim 11 or 12, wherein: The force applied by the mechanism for moving the load is constrained by a predetermined maximum threshold.

14. A method according to the preceding claim, wherein: The mechanism comprises an extendable and retractable manipulator boom (10), the extension force of the manipulator boom being limited by the predetermined maximum threshold.

15. The method according to the preceding claim, wherein: A hydraulic cylinder (16) is provided for extending and retracting the arm (10), and wherein a predetermined maximum threshold is set for the operating pressure of the cylinder (16), thereby defining the maximum longitudinal operating extension allowed for the arm (10) depending on the load.

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