Boom floating control system for construction machine

Abstract

One aspect of the present disclosure provides a boom floating control system for a construction machine including a boom, an arm, and an attachment, the boom floating control system comprising: an electromechanical actuator connected to the boom to raise the boom as the electromechanical actuator is extended and lower the boom as the electromechanical actuator is retracted, the electromechanical actuator including an electric motor configured to convert electric energy into a rotational motion and a linear actuator configured to convert the rotational motion of the electric motor into a linear motion; and a controller configured to, when a boom floating function is activated, perform control such that, with respect to a first external force acting in a direction in which the linear actuator extends, a maximum torque of the electric motor generable in a direction resisting the first external force is limited.

Description

Construction machinery boom floating control system

[0001] The present disclosure relates to a boom floating control system for construction machinery. In a particular aspect, the present disclosure relates to a boom floating control system for construction machinery in which an electromechanical actuator is applied instead of a hydraulic cylinder. The present disclosure may be applied to heavy vehicles such as trucks, buses, and construction equipment among other vehicle types. While the present disclosure may be described with respect to specific vehicles, the present disclosure is not limited to any specific vehicle.

[0002] Construction machinery is known to perform work by pressurizing a fluid, sending the pressurized fluid to a hydraulic actuator, and having the hydraulic actuator obtain power from the pressurized fluid to operate a working device. For example, construction machinery such as an excavator is one such example.

[0003] Construction machinery can perform not only the loading, transport, and unloading of soil at construction sites, but also leveling operations by moving the working device back and forth to level the ground. To perform such leveling operations, the operator must finely control the movement of the working device so that the load applied to the ground is properly maintained.

[0004] However, when performing leveling work, if the control of the working device is not precise, the force applied by the working device to the ground is too great, causing the device to dig into the ground; conversely, if the force applied by the working device to the ground is too small, the leveling work is not performed properly. As such, when construction machinery performs leveling work, the operator must operate the working device precisely, but in reality, precise control is difficult, so the work desired by the operator may not be properly performed.

[0005] To solve these problems, construction machinery has a boom floating function, and through this boom floating function, the operator can prevent unintended operation of the work device in advance while performing leveling work, etc.

[0006] In construction machinery equipped with conventional hydraulic actuators, when the boom floating function is activated, the head chamber and rod chamber of the boom cylinder communicate with each other to share pressure between the chambers, and the net flow between the two chambers is altered by the movement of the cylinder rod, which is actuated by an external force (e.g., arm cylinder). Additionally, the boom flow hydraulic circuit allows the cylinder flow to flow freely between the cylinder and the tank. Thus, the boom actuator is controlled by external forces (e.g., other actuators or gravity) rather than by the operator's commands to the boom actuator, and the working device can move along the curvature of the work surface or road surface.

[0007] However, when an electromechanical actuator (EMA) is used instead of a hydraulic actuator as a device to operate the boom, the aforementioned hydraulic boom floating function cannot be used. Therefore, to achieve the same boom floating function with an electromechanical actuator, a new control method is required in terms of electromechanical actuator control.

[0008] The present disclosure is intended to solve the problems of the aforementioned prior art, and the purpose of the present disclosure is to provide a boom floating control system for construction machinery to which an electromechanical actuator is applied.

[0009] A first aspect of the present disclosure provides a boom floating control system for a construction machine comprising a boom, an arm, and an attachment, wherein the system comprises an electromechanical actuator connected to the boom to raise the boom as it extends and lower the boom as it retracts, the electromechanical actuator comprising an electric motor that converts electrical energy into rotational motion and a linear actuator that converts the rotational motion of the electric motor into linear motion, and a controller that controls the system to limit the maximum torque of the electric motor that can be generated in a direction resisting the first external force, with respect to a first external force acting in a direction extending the linear actuator when the boom floating function is activated.

[0010] The boom floating control system of a construction machine may further include, optionally, an operator input device for activating the boom floating function and a boom operating device for inputting an operation signal to raise or lower the boom, wherein the boom floating function is activated as the operator input device is turned ON and the boom operating device is operated in the direction of lowering the boom.

[0011] Optionally, the controller may be a boom floating control system for construction machinery characterized by not limiting the maximum torque of the electric motor that can be generated in a direction resisting the second external force acting in a direction of contracting the linear actuator.

[0012] Optionally, the above controller may be a boom floating control system for a construction machine characterized by controlling the boom floating function not to be activated when it is determined that the construction machine is in a jack-up state.

[0013] Optionally, the controller may be a boom floating control system for a construction machine characterized by determining that the construction machine is in a jack-up state when the feedback torque of the electric motor acts in a direction that resists the first external force.

[0014] A second aspect of the present disclosure provides a boom floating control system for a construction machine comprising a boom, an arm, and an attachment, wherein the system comprises an electromechanical actuator connected to the boom to raise the boom as it retracts and lower the boom as it extends, the electromechanical actuator comprising an electric motor that converts electrical energy into rotational motion and a linear actuator that converts the rotational motion of the electric motor into linear motion, and a controller that controls the system to limit the maximum torque of the electric motor that can be generated in a direction resisting a second external force acting in a direction of retracting the linear actuator when the boom floating function is activated.

[0015] Optionally, the controller may be a boom floating control system for construction machinery characterized by not limiting the maximum torque of the electric motor that can be generated in a direction resisting the first external force with respect to the first external force acting in a direction extending the linear actuator.

[0016] According to the present disclosure, even in construction machinery equipped with an electromechanical actuator, the boom floating function can be used, allowing the operator to easily perform leveling work even if they are not proficient in operation and reducing work fatigue.

[0017] The effects of the present disclosure are not limited to the effects described above, and should be understood to include all effects that can be inferred from the detailed description of the content of the disclosure or the composition of the disclosure described in the claims.

[0018] The disclosed aspects, embodiments (including any preferred embodiments), and / or accompanying claims may be appropriately combined with one another as will be obvious to those skilled in the art.

[0019] Additional features and benefits are disclosed in the following description, claims, and drawings, and in part will be readily apparent to those skilled in the art or recognized by practicing the disclosures as set forth in this specification.

[0020] FIG. 1 is a drawing illustrating a construction machine according to one aspect of the present disclosure.

[0021] FIG. 2 is a configuration diagram of a boom floating control system for construction machinery according to one aspect of the present disclosure.

[0022] FIGS. 3(a) and (b) are drawings for illustrating quadrant motion control of an electric motor according to one aspect of the present disclosure.

[0023] FIG. 4 shows a construction machine in a state where a working device according to one aspect of the present disclosure is in contact with the ground.

[0024] FIG. 5 shows a construction machine with a working device according to one aspect of the present disclosure suspended in the air.

[0025] FIG. 6 shows a construction machine in a jack-up state according to one aspect of the present disclosure.

[0026] FIGS. 7(a) and (b) are drawings for illustrating quadrant motion control of an electric motor with the boom floating function activated according to one aspect of the present disclosure.

[0027] FIG. 8 shows a construction machine according to another aspect of the present disclosure.

[0028] FIGS. 9 (a) and (b) are drawings for illustrating quadrant motion control of an electric motor according to another aspect of the present disclosure.

[0029] FIG. 10 (a) and (b) are drawings for illustrating quadrant motion control of an electric motor with the boom floating function activated according to another aspect of the present disclosure.

[0030] The detailed description below provides information and examples of the disclosed technology with sufficient detail to enable those skilled in the art to practice the present disclosure. However, the present disclosure may be embodied in various different forms and is therefore not limited to the aspects described herein. Furthermore, in order to clearly illustrate the present disclosure in the drawings, parts unrelated to the description have been omitted, and similar parts throughout the specification have been given similar reference numerals.

[0031] The terms used herein are merely for describing specific aspects and are not intended to limit the disclosure. As used herein, the singular form is intended to include the plural form unless the context clearly indicates otherwise. As used herein, the term “and / or” includes any combination of one or more of the related listed items. As used herein, the terms “comprising” and “comprising” specify the presence of the mentioned features, integers, steps, actions, elements, and / or components, but do not exclude the presence or addition of one or more other functions, integers, steps, operations, elements, components, and / or groups thereof.

[0032] While terms such as first, second, etc. may be used in this specification to describe various elements, it will be understood that these elements should not be limited by such terms. These terms are used only to distinguish one element from another. For example, without departing from the scope of the rights of this disclosure, a first component may be named a second component, and similarly, a second component may be named a first component.

[0033] Relative terms such as "below," "above," "up," "down," "horizontal," or "vertical" may be used in this specification to describe the relationship between one element and another as illustrated in the drawings. It will be understood that these terms and the terms discussed above are intended to include different orientations of the device in addition to the orientations illustrated in the drawings. When a component is referred to as being "connected" or "combined" to another component, it will be understood that it may be directly connected to or combined with the other component, or that there may be an intervening component. In contrast, when an element is referred to as being "directly connected" or "directly combined" to another element, no intermediate element exists.

[0034] Unless otherwise defined, all terms used herein (including technical and scientific terms) have the same meaning as generally understood by those skilled in the art to which this disclosure pertains. Terms used herein should be interpreted as having a meaning consistent with their meaning in the context of this specification and related technology, and should be further understood that they should not be interpreted in an idealized or overly formal sense unless explicitly defined herein.

[0035] Hereinafter, one aspect of the present disclosure will be described in detail with reference to the attached drawings.

[0036] FIG. 1 is a drawing illustrating a construction machine according to one aspect of the present disclosure.

[0037] Referring to FIG. 1, a construction machine (1) according to one aspect of the present disclosure may be, for example, an excavator, preferably an electric excavator. The present disclosure may be described with respect to an excavator, but is not limited thereto. An excavator is a device capable of excavating objects, and may include various types of excavators capable of performing excavation work in various ways, such as soil transport work, building demolition work, ground leveling work, etc.

[0038] The construction machine (1) may include a lower body (10) and an upper structure (20) supported to swing on the lower body (10). The upper structure (20) may include an upper slewing body and a working device. The working device may include, for example, a boom (30), an arm (40), and an attachment (50). The attachment (50) may be, for example, a bucket.

[0039] The lower driving body (10) is configured to support the load of a work device including an upper slewing body, a boom (30), an arm (40), and an attachment (50), while simultaneously moving the construction machine (1). The lower driving body (10) includes a pair of left and right driving sections and can travel in a straight line in the forward and backward directions, change direction to the left or right by steering, or change direction in the opposite direction by turning.

[0040] The upper pivot body is configured to be supported on the lower driving body (10) and is designed to swing on the lower driving body (10) by means of a pivoting device including a swing motor, a swing reduction gear, etc.

[0041] A cab for the construction machine (1) may be installed on the upper slewing body, and a driver's seat may be provided in the cab where an operator can sit. In front of the driver's seat, various operating levers or pedals for operating the work or driving of the construction machine (1) may be provided, and a swing lever may also be provided so that the operator can control the swing of the upper slewing body.

[0042] The arm (40) is connected to the attachment (50) and the boom (30), respectively, and in one embodiment, the boom (30), arm (40), and attachment (50) are connected via joints in the order from the upper slewing body, and each joint can be moved by an electromechanical actuator.

[0043] For example, the arm (40) may be connected to a boom (30) connected to an upper slewing body at one end and to an attachment (50) at the other end. Each of the boom (30), arm (40), and attachment (50) may rotate on one or more axes by an electromechanical actuator, and the attachment (50), for example, a bucket, may hold excavation material (e.g., soil) on the ground as it rotates.

[0044] Since these boom (30), arm (40) and attachment (50) are installed while being supported forward on the upper slewing body, when the upper slewing body swings, the boom (30), arm (40) and attachment (50) swing together with the upper slewing body.

[0045] The construction machine (1) can be configured, for example, as an electro-hydraulic system, and its operation can be controlled electronically by a controller.

[0046] FIG. 2 is a configuration diagram of a boom floating control system for construction machinery according to one aspect of the present disclosure.

[0047] Referring to FIGS. 1 and 2, a boom floating control system (1000) of a construction machine including a boom, an arm and an attachment may include an electromechanical actuator (100), a controller (200), an operator input device (300), and a boom operating device (400).

[0048] As illustrated in FIGS. 3 and 4, an electromechanical actuator (100) can be connected to the boom (30) in the lower direction of the boom (30). In other words, the electromechanical actuator (100) can be connected to the boom (30) to raise the boom (30) as it extends and to lower the boom (30) as it retracts.

[0049] The electromechanical actuator (100) may include a linear actuator (110) that converts the rotational motion of the electric motor (120) into linear motion. Any type of actuator capable of converting the rotational motion of the electric motor (120) into linear motion of a moving part may be applied as a linear actuator (110). For example, the linear actuator (110) may be a screw type or a rack and pinion type.

[0050] The electromechanical actuator (100) may include an electric motor (120) that converts electrical energy into rotational motion. The electric motor (120) may preferably be a DC motor, such as a brushless DC motor (BLDC), for example. However, it is not limited thereto, and the electric motor (120) may be an AC motor. The electric motor (120) may receive electrical energy from a rechargeable on-board battery pack, such as a lithium-ion battery pack, for example.

[0051] The electromechanical actuator (100) may include a mechanical brake (130) (also called a “safety brake”) for keeping the linear actuator (110) in place when the electric motor (120) is turned off.

[0052] The operator input device (300) is a device that receives a request from an operator to activate the boom floating function. For example, the operator input device (300) may be provided in the form of a switch or in the form of a display. That is, the operator can activate the boom floating function through the operator input device (300).

[0053] The boom operating device (400) is a device that receives a request from an operator operating an electromechanical actuator (100) connected to the boom (30). That is, when the operator inputs a boom-up request through the boom operating device (400), the electromechanical actuator (100) is operated accordingly to perform a boom-up operation, and when the operator inputs a boom-down request through the boom operating device (400), the electromechanical actuator (100) is operated accordingly to perform a boom-down operation. For example, the boom operating device (400) may be provided in the form of a lever, and when the lever in a neutral state is pushed forward, a boom-down request is input to the boom operating device (400), and when the lever is pulled backward, a boom-up request is input to the boom operating device (400).

[0054] According to one embodiment, the boom floating function can be activated when the operator input device (300) is turned ON and the boom operating device (400) is operated in the direction of lowering the boom. When the boom floating function is activated, the operator can make the work device (boom, arm, and bucket) perform the leveling operation, which is the main purpose of the boom floating function, by controlling only the arm operating device (not shown) while the boom operating device (400) is fully operated in the boom down direction. At this time, the boom (30) can be controlled to move geometrically according to the movement of the arm (40) and the bucket (50).

[0055] FIGS. 3(a) and (b) are drawings for explaining quadrant motion control of an electric motor according to one aspect of the present disclosure, FIG. 4 shows a construction machine in a state where a working device according to one aspect of the present disclosure is in contact with the ground, FIG. 5 shows a construction machine in a state where a working device according to one aspect of the present disclosure is lifted into the air, and FIG. 6 shows a construction machine in a jack-up state according to one aspect of the present disclosure.

[0056] Referring to FIG. 3, in the quadrant motion control graph of the electric motor, the X-axis represents the speed (rotational speed) of the electric motor (120). Here, the positive direction of the X-axis represents the speed of the electric motor (120) in the direction (S1) of extending the linear actuator (110), and the negative direction of the X-axis represents the speed of the electric motor (120) in the direction (S2) of contracting the linear actuator (110).

[0057] Additionally, referring to FIG. 3, in the quadrant motion control graph of the electric motor, the Y-axis represents the torque of the electric motor (120) capable of resisting the external force (F) acting on the linear actuator (110). Here, the positive direction of the Y-axis represents the torque of the electric motor (120) capable of resisting the second external force (compression force, F2) acting in the direction of contracting the linear actuator (110), and the negative direction of the Y-axis represents the torque of the electric motor (120) capable of resisting the first external force (extraction force, F1) acting in the direction of extending the linear actuator (110).

[0058] Referring to FIGS. 3, 4, and 6, when the boom floating function is not activated, if the boom operating device (400) is operated in a direction that retracts the linear actuator (110) while the attachment (50) (e.g., bucket) is brought into contact with the ground and the arm is out, the boom is lowered, and thereby the attachment (50) is supported on the ground and the lower vehicle body (10) can be partially lifted off the ground in a jack-up state. That is, as the attachment (50) is supported on the ground, a first external force (F1) is applied to the electromechanical actuator (100) in a direction that extends the linear actuator (110), and since torque can be exerted by resisting the external force when the boom floating function is not activated, the electric motor (120) can generate torque (negative direction of the Y-axis) in a direction that resists the first external force (F1) (see third quadrant (Q3) in FIG. 3 (b)).

[0059] Additionally, when the boom floating function is not activated, if the boom operating device (400) is operated in a direction that contracts the linear actuator (110) while the arm is in contact with the ground after the attachment (50) (e.g., bucket) is brought into contact with the ground, the boom is lowered, and thereby the attachment (50) is supported on the ground and a part of the lower vehicle body (10) is lifted off the ground, thereby creating a jack-up state. That is, as the attachment (50) is supported on the ground, a first external force (F1) is applied to the electromechanical actuator (100) in a direction that extends the linear actuator (110), and since torque can be exerted by resisting the external force when the boom floating function is not activated, the electric motor (120) can generate torque (negative direction of the Y-axis) in a direction that resists the first external force (F1) (see third quadrant (Q3) in FIG. 3 (b)).

[0060] FIGS. 7(a) and (b) are drawings for illustrating quadrant motion control of an electric motor with the boom floating function activated according to one aspect of the present disclosure.

[0061] Referring to FIGS. 4 and 7, when the boom floating function is activated, the controller (200) can control the electric motor (120) to limit the maximum torque that can be generated in a direction resisting the first external force (F1) with respect to the first external force (F1) acting in a direction extending the linear actuator (110).

[0062] That is, when the boom floating function is activated, the boom operating device (400) is operated in the direction of retracting the linear actuator (110) while the arm is out, after the attachment (50) (e.g., bucket) is brought into contact with the ground. Since the maximum torque of the electric motor (120) (negative direction of the Y-axis) in the direction resisting the first external force (F1) generated as the attachment (50) is supported on the ground is limited to a very low (or nearly zero) value by the controller (200), the jack-up state is not caused. Consequently, the boom (30) moves in the boom-down direction (the direction in which the linear actuator retracts) due to the geometric movement (external force) and self-weight resulting from the arm out (see third quadrant (Q3) in FIG. 7 (b)).

[0063] Additionally, when the boom floating function is activated, the boom operating device (400) is operated in a direction that retracts the linear actuator (110) while the arm is in, after the attachment (50) (e.g., bucket) is brought into contact with the ground. Since the maximum torque of the electric motor (120) (negative direction of the Y-axis) in the direction resisting the first external force (F1) generated as the attachment (50) is supported on the ground is limited to a very low (or nearly zero) value by the controller (200), the jack-up state is not caused. Consequently, the boom (30) moves in the boom-up direction (the direction in which the linear actuator extends) due to the geometric movement (external force) caused by the arm in (see the fourth quadrant (Q4) in FIG. 7 (b)).

[0064] In this way, when the boom floating function is activated, even if the operator is not proficient in operation, the working device (boom, arm, and bucket) can easily perform a leveling operation by controlling only the arm operating device while the boom operating device (400) is fully operated in the boom-down direction. That is, the operator's work fatigue can be reduced through the boom floating function.

[0065] Meanwhile, according to one embodiment, the controller (200) does not limit the maximum torque of the electric motor (120) that can be generated in a direction resisting the second external force (F2) with respect to the second external force (F2) acting in a direction that contracts the linear actuator (110).

[0066] For example, referring to FIGS. 5 and 7, when the work device is suspended in the air, a second external force (F2) acts in a direction that retracts the linear actuator (110) due to the self-weight of the work device, and the maximum torque of the electric motor (120) (positive direction of the Y-axis) in the direction resisting the second external force (F2) is not limited by the controller (200). Therefore, when the boom is lowered from the air while the boom floating function is activated, the movement speed (downward direction) of the boom moves according to the operator's boom control device (400) request, just as in normal operation (see second quadrant (Q2) in FIG. 7 (b)). In addition, when the boom is raised in the air while the boom floating function is activated, the boom floating function is deactivated by the boom raising operation, so the movement speed (upward direction) of the boom moves according to the operator's boom operating device (400) as in normal operation (see first quadrant (Q1) in FIG. 7 (b)).

[0067] According to one embodiment, the controller (200) can control the boom floating function so as not to activate when the construction machine (1) is in a jack-up state. When the boom floating function is activated while the work machine (1) is in a jack-up state, the work machine (1) may suddenly descend due to its own weight, which may cause a safety accident.

[0068] Here, the controller (200) can determine that the construction machine (1) is in a jack-up state when the feedback torque of the electric motor (120) is in a negative direction. The fact that the feedback torque is in a negative direction means that when the attachment (50) is supported on the ground and the front part of the lower vehicle body (10) is lifted into the air, the feedback torque of the electric motor (120) is measured in a direction that resists the first external force (F1) acting in the direction of extending the linear actuator (110).

[0069] FIG. 8 shows a construction machine according to another aspect of the present disclosure, FIG. 9 (a) and (b) are drawings for explaining quadrant motion control of an electric motor according to another aspect of the present disclosure, and FIG. 10 (a) and (b) are drawings for explaining quadrant motion control of an electric motor with a boom floating function activated according to another aspect of the present disclosure.

[0070] Hereinafter, with reference to FIGS. 8 and FIGS. 10, the differences from the first embodiment described above will be explained mainly.

[0071] Referring to FIG. 8, the electromechanical actuator (100) in the construction machine (1') can be connected to the boom (30) in an upward direction of the boom (30), unlike in the first embodiment. In other words, the electromechanical actuator (100) can be connected to the boom (30) to raise the boom (30) as it contracts and to lower the boom (30) as it extends.

[0072] Referring to FIG. 9, in the quadrant motion control graph of the electric motor, the X-axis represents the speed (rotational speed) of the electric motor (120). Here, the positive direction of the X-axis represents the speed of the electric motor (120) in the direction (S1) of extending the linear actuator (110), and the negative direction of the X-axis represents the speed of the electric motor (120) in the direction (S2) of contracting the linear actuator (110).

[0073] Additionally, referring to FIG. 9, in the quadrant motion control graph of the electric motor, the Y-axis represents the torque of the electric motor (120) capable of resisting the external force (F) acting on the linear actuator (110). Here, the positive direction of the Y-axis represents the torque of the electric motor (120) capable of resisting the second external force (compression force, F2) acting in the direction of contracting the linear actuator (110), and the negative direction of the Y-axis represents the torque of the electric motor (120) capable of resisting the second external force (extraction force, F1) acting in the direction of extending the linear actuator (110).

[0074] Referring to FIGS. 8 and 9, when the boom floating function is not activated, if the boom operating device (400) is operated in a direction that extends the linear actuator (110) while the arm is out, after the attachment (50) (e.g., bucket) is brought into contact with the ground, the boom is lowered, and thereby the attachment (50) is supported on the ground and the lower vehicle (10) is partially lifted off the ground, creating a jack-up state. That is, as the attachment (50) is supported on the ground, a second external force (F2) acts on the electromechanical actuator (100) in a direction that contracts the linear actuator (110), and since torque can be exerted by resisting the external force when the boom floating function is not activated, the electric motor (120) can generate torque (positive direction of the Y-axis) in a direction that resists the second external force (F2) (see first quadrant (Q1) in FIG. 9 (b)).

[0075] Additionally, when the boom floating function is not activated, if the boom operating device (400) is operated in a direction that extends the linear actuator (110) while the arm is in contact with the ground after the attachment (50) (e.g., bucket) is brought into contact with the ground, the boom is lowered, and thereby the attachment (50) is supported on the ground and the lower vehicle body (10) is partially lifted off the ground, thereby creating a jack-up state. That is, as the attachment (50) is supported on the ground, a second external force (F2) acts on the electromechanical actuator (100) in a direction that contracts the linear actuator (110), and since torque can be exerted by resisting the external force when the boom floating function is not activated, the electric motor (120) can generate torque (positive direction of the Y-axis) in a direction that resists the second external force (F2) (see first quadrant (Q1) in FIG. 9 (b)).

[0076] FIG. 10 (a) and (b) are drawings for illustrating quadrant motion control of an electric motor with the boom floating function activated according to one aspect of the present disclosure.

[0077] Referring to FIG. 10, when the boom floating function is activated, the controller (200) can control the electric motor (120) to limit the maximum torque that can be generated in a direction resisting the second external force (F2) with respect to the second external force (F2) acting in a direction that contracts the linear actuator (110).

[0078] That is, when the boom floating function is activated, the boom operating device (400) is operated in the direction of extending the linear actuator (110) while the arm is out, after the attachment (50) (e.g., bucket) is brought into contact with the ground. Since the maximum torque of the electric motor (120) (positive direction of the Y-axis) in the direction resisting the second external force (F2) generated as the attachment (50) is supported on the ground is limited to a very low (or nearly zero) by the controller (200), the jack-up state is not caused. As a result, the boom (30) moves in the boom-down direction (the direction in which the linear actuator extends) due to the geometric movement (external force) and self-weight resulting from the arm out (see the first quadrant (Q1) in FIG. 10 (b)).

[0079] Additionally, when the boom floating function is activated, the boom operating device (400) is operated in a direction that extends the linear actuator (110) while the arm is in, after the attachment (50) (e.g., bucket) is brought into contact with the ground. Since the maximum torque of the electric motor (120) (positive direction of the Y-axis) in the direction resisting the second external force (F2) generated as the attachment (50) is supported on the ground is limited to a very low (or nearly zero) value by the controller (200), the jack-up state is not caused. Consequently, the boom (30) moves in the boom-up direction (the direction in which the linear actuator contracts) due to the geometric movement (external force) caused by the arm in (see second quadrant (Q2) in FIG. 10 (b)).

[0080] Meanwhile, according to one embodiment, the controller (200) does not limit the maximum torque of the electric motor (120) that can be generated in a direction resisting the first external force (F1) with respect to the first external force (F1) acting in a direction that extends the linear actuator (110).

[0081] For example, when the work device is suspended in the air, a first external force (F1) is applied in a direction that extends the linear actuator (110) by the self-weight of the work device, and the maximum torque of the electric motor (120) in the direction resisting the first external force (F1) (negative direction of the Y-axis) is not limited by the controller (200). Therefore, when the boom is lowered in the air while the boom floating function is activated, the movement speed (downward direction) of the boom moves according to the operator's boom control device (400) request, just like in normal operation (see the fourth quadrant (Q4) in FIG. 10 (b)). In addition, when the boom is raised in the air while the boom floating function is activated, the boom floating function is deactivated by the boom raising operation, so the movement speed (upward direction) of the boom moves according to the operator's boom operating device (400) as in normal operation (see third quadrant (Q3) in FIG. 10 (b)).

[0082] As such, according to the present disclosure, even in construction machinery equipped with an electromechanical actuator, the boom floating function can be used, allowing the operator to easily perform leveling work even if they are not proficient in operation, and reducing work fatigue.

[0083] It should be understood that the present disclosure is not limited to the embodiments described above and illustrated in the drawings. Rather, those skilled in the art will recognize that many changes and modifications may be made within the scope of the present disclosure and the appended claims. In the drawings and specification, aspects are disclosed merely for illustrative purposes and not for the purpose of limitation, and the scope of the concept of the present disclosure is set forth in the following claims.

[0084]

[0085] Explanation of the symbols

[0086] 1, 1' construction machinery

[0087] 10 Underbody

[0088] 20 Superstructure

[0089] 30 Boom

[0090] 40 aam

[0091] 50 attachments

[0092] 100 electromechanical actuators

[0093] 110 Linear Actuator

[0094] 120 electric motor

[0095] 130 mechanical brakes

[0096] 200 controllers

[0097] 300 Operator Input Device

[0098] 400 Boom Control Device

Claims

1. A boom floating control system for construction machinery including a boom, an arm, and an attachment, An electromechanical actuator connected to a boom to raise the boom as it extends and lower the boom as it retracts, comprising an electric motor that converts electrical energy into rotational motion and a linear actuator that converts the rotational motion of the electric motor into linear motion; and A boom floating control system for a construction machine, comprising a controller that controls to limit the maximum torque of the electric motor that can be generated in a direction resisting the first external force, with respect to a first external force acting in a direction extending the linear actuator when the boom floating function is activated.

2. In Paragraph 1, An operator input device for activating the boom floating function; and It further includes a boom operating device for inputting an operation signal to raise or lower the boom, and A boom floating control system for construction machinery, characterized in that the boom floating function is activated as the operator input device is turned ON and the boom operating device is operated in a direction to lower the boom.

3. In Paragraph 1, The above controller is, A boom floating control system for construction machinery, characterized by not limiting the maximum torque of the electric motor that can be generated in a direction resisting the second external force acting in a direction that contracts the linear actuator.

4. In Paragraph 1, A boom floating control system for a construction machine, characterized in that the controller controls the boom floating function not to be activated when it is determined that the construction machine is in a jack-up state.

5. In Paragraph 4, A boom floating control system for a construction machine, characterized in that the controller determines that the construction machine is in a jack-up state when the feedback torque of the electric motor acts in a direction that resists the first external force.

6. A boom floating control system for construction machinery including a boom, an arm, and an attachment, An electromechanical actuator connected to a boom to raise the boom as it contracts and lower the boom as it extends, comprising an electric motor that converts electrical energy into rotational motion and a linear actuator that converts the rotational motion of the electric motor into linear motion; and A boom floating control system for a construction machine, comprising a controller that controls to limit the maximum torque of the electric motor that can be generated in a direction resisting the second external force acting in a direction of contracting the linear actuator when the boom floating function is activated.

7. In Paragraph 6, The above controller is, A boom floating control system for construction machinery, characterized by not limiting the maximum torque of the electric motor that can be generated in a direction resisting the first external force with respect to a first external force acting in a direction extending the linear actuator.

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