Motor-driven hydrostatic transmission for agricultural work vehicle

Abstract

An agricultural work vehicle equipped with a hydrostatic transmission (HST) is provided. The agricultural work vehicle may comprise: a hydraulic pump including a pump swash plate and supplying a working fluid according to the angle of the pump swash plate; a swash plate control motor for generating power for adjusting the angle of the pump swash plate; an actuator for operating the swash plate shaft of the pump swash plate by using the power generated by the swash plate control motor; a link unit for transmitting the power generated by the swash plate control motor to the actuator; and a control unit for controlling the rotation of the swash plate control motor on the basis of the manipulation state of an HST manipulation unit.

Description

Motor-driven hydrostatic transmission for agricultural work vehicles

[0001] The present disclosure relates to a motor-driven hydrostatic transmission for an agricultural work vehicle.

[0002] Agricultural work vehicles are vehicles used for agricultural work, such as rice transplanters, combines, and tractors. For example, a tractor can be equipped with various implements necessary for agricultural work and perform the required agricultural tasks.

[0003] A Hydro-Static Transmission (HST) is a transmission that uses a hydraulic pump to convert power generated from a power source (e.g., engine, electric motor) into hydraulic pressure, and transmits driving force by rotating a hydraulic motor using this hydraulic pressure. Since HSTs perform stepless shifting, they enable precise speed control for various operating conditions and smooth operation without shifting shock. Because HSTs transmit power via hydraulics, they are also well-suited to maintaining high torque output for extended periods.

[0004] Electronic control means (e.g., TCU (Transmission Control Unit), etc.) may be used to adjust the angle of the pump swash plate of a hydraulic pump. For example, an agricultural work vehicle may be equipped with a servo piston connected to the pump swash plate and a proportional control valve that regulates the flow rate to advance or retract the servo piston, and the electronic control means can adjust the angle of the pump swash plate by controlling the proportional control valve.

[0005] However, while this control method requires a significant level of precision in controlling the proportional control valve, there is a risk of errors in sequential control due to factors such as the temperature or viscosity of the hydraulic oil when the hydrostatic transmission is used for extended periods, and developing and implementing such a system also incurs substantial costs.

[0006] The present disclosure is intended to provide a motor-driven hydrostatic transmission for an agricultural work vehicle that uses a motor to adjust the angle of a pump swash plate.

[0007] According to one aspect of the present disclosure, an agricultural work vehicle equipped with a hydro-static transmission (HST) may include a pump swash plate, a hydraulic pump that supplies working fluid according to the angle of the pump swash plate, a swash plate control motor that generates power to adjust the angle of the pump swash plate, an actuator that operates a swash plate shaft of the pump swash plate using the power generated by the swash plate control motor, a link portion that transmits the power generated by the swash plate control motor to the actuator, and a control portion that controls the rotation of the swash plate control motor based on the operating state of the HST operating portion.

[0008] In one embodiment, the actuator may include a spool that moves linearly by rotational power transmitted through the link portion, a servo piston that moves forward or backward by a change in hydraulic pressure due to the linear movement of the spool, and a cylinder that provides a space for the servo piston to move forward or backward.

[0009] In one embodiment, the actuator may further include a connecting member installed on the servo piston and rotating the swash plate shaft according to the forward or backward movement of the servo piston.

[0010] In one embodiment, when the HST operating unit is operated in a direction to advance the servo piston, the control unit rotates the swash plate control motor in a first direction, the spool moves linearly in a second direction according to the rotation of the swash plate control motor, the hydraulic pressure in one side space of the servo piston within the cylinder rises, the hydraulic pressure in the other side space of the servo piston within the cylinder falls, and the servo piston can advance according to the rise in hydraulic pressure in the one side space and the fall in hydraulic pressure in the other side space.

[0011] In one embodiment, when the HST operating unit is operated in a direction to retract the servo piston, the control unit rotates the swash plate control motor in a third direction, and the spool moves linearly in a fourth direction according to the rotation of the swash plate control motor, and the hydraulic pressure in the one-sided space of the servo piston within the cylinder decreases, and the hydraulic pressure in the other-sided space of the servo piston within the cylinder increases, and the servo piston can retract according to the decrease in hydraulic pressure in the one-sided space and the increase in hydraulic pressure in the other-sided space, and the third direction is different from the first direction, and the fourth direction is different from the second direction.

[0012] In one embodiment, the link portion may include a rotating member coupled to the rotation axis of the swash plate control motor, and the rotating member may include one or more eccentric pins that transmit rotational power of the swash plate control motor to the spool so that the spool moves in a straight line.

[0013] In one embodiment, the rotating member may further include a neutral return shaft, and the link portion may further include a neutral spring, one end of which is connected to the housing of the hydrostatic transmission and the other end of which is connected to the neutral return shaft to return the rotating member to a neutral position by means of an elastic force.

[0014] In one embodiment, the link portion may include a first gear coupled to the rotation axis of the swash plate control motor and a second gear formed by meshing with the first gear, and the second gear may include one or more eccentric pins that transmit rotational power of the swash plate control motor to the spool so that the spool moves in a straight line.

[0015] In one embodiment, the second gear may have a larger diameter than the first gear.

[0016] In one embodiment, the second gear may further include a neutral return shaft, and the link portion may further include a neutral spring, one end of which is connected to the housing of the hydrostatic transmission and the other end of which is connected to the neutral return shaft to return the second gear to a neutral position by means of elastic force.

[0017] A motor-driven hydrostatic transmission according to one embodiment is robust to various working environments, can simplify control variables, can be implemented at a lower cost, and has enhanced durability.

[0018] FIG. 1 is a block diagram illustrating the components of an agricultural work vehicle according to one embodiment.

[0019] FIG. 2 is a reference diagram schematically illustrating the structure of a hydrostatic transmission according to one embodiment.

[0020] FIG. 3 is intended to explain the operation of an actuator according to one embodiment.

[0021] FIGS. 4a, 4b, and 4c are intended to illustrate the operation of a neutral spring according to one embodiment.

[0022] FIG. 5 is a reference diagram schematically illustrating the structure of a hydrostatic transmission including a reduction gear according to one embodiment.

[0023] The terms used in this disclosure have been selected to be as widely used and general as possible, taking into account their functions within this disclosure; however, these terms may vary depending on the intent of those skilled in the art, case law, the emergence of new technologies, etc. In specific cases, terms have been selected at the applicant's discretion, and in such cases, their meanings will be described in detail in the relevant explanatory sections. Therefore, terms used in this disclosure should be defined not merely by their names, but based on their meanings and the overall content of this disclosure.

[0024] Singular expressions may include plural expressions unless the context clearly indicates otherwise. Terms used herein, including technical or scientific terms, may have the same meaning as generally understood by those skilled in the art as described in this specification.

[0025] In this disclosure, the term “and / or” includes a combination of a plurality of related described components or any of a plurality of related described components.

[0026] Terms including ordinal numbers, such as "first" or "second," used in this disclosure may be used to describe various components, but said components should not be limited by said terms. Such terms are used solely for the purpose of distinguishing one component from another.

[0027] In the present disclosure, the expression “at least one of a, b, or c” may refer to “a,” “b,” “c,” “a and b,” “a and c,” “b and c,” “all of a, b, and c,” or variations thereof.

[0028] When a part of a specification is described as "comprising" a certain component, this means that, unless specifically stated otherwise, it does not exclude other components but may include additional components. Furthermore, terms such as "part" or "module" as used in the specification refer to a unit that processes at least one function or operation, and this may be implemented in hardware or software, or as a combination of hardware and software.

[0029] Hereinafter, embodiments of the present disclosure are described in detail with reference to the attached drawings so that those skilled in the art can easily implement the present invention. However, the present disclosure may be embodied in various different forms and is not limited to the embodiments described herein. Furthermore, in order to clearly explain the present disclosure in the drawings, parts unrelated to the explanation have been omitted, and similar parts throughout the specification have been given similar reference numerals. In addition, the reference numerals used in each drawing are for the purpose of explaining each drawing, and different reference numerals used in different drawings are not intended to represent different elements.

[0030] FIG. 1 is a block diagram for explaining the components of an agricultural work vehicle according to one embodiment, and FIG. 2 is a reference diagram schematically illustrating the structure of a hydrostatic transmission according to one embodiment.

[0031] Referring to FIGS. 1 and 2, an agricultural work vehicle (100) may include a hydro-static transmission (HST) (110), an actuator (120), a linkage unit (130), a motor for controlling a swash plate (140), a control unit (150), and an HST operating unit (160). However, not all of the illustrated components are essential components. The agricultural work vehicle (100) may be implemented with more components than those illustrated in FIG. 1, or with fewer components.

[0032] The hydrostatic transmission (110) can transmit power generated from a power source (e.g., engine, electric motor, etc.) to the wheels.

[0033] The hydrostatic transmission (110) may include a hydraulic pump (112) and a hydraulic motor (114).

[0034] The hydraulic pump (112) and the hydraulic motor (114) can be connected via a hydraulic line.

[0035] The hydraulic pump (112) can supply hydraulic fluid to the hydraulic line. The hydraulic pump (112) can convert power generated from a power source into hydraulic energy and supply it to the hydraulic line. The hydraulic fluid can flow along the hydraulic line to rotate the hydraulic motor (114).

[0036] The hydraulic pump (112) may include a swash plate (210). The hydraulic pump (112) may vary the supply flow rate according to the angle of the swash plate (210). For example, if the angle of the swash plate (210) is within a predetermined neutral range, the hydraulic pump (112) does not discharge hydraulic fluid, so that power generated from the power source is not transmitted to the wheels. The hydraulic pump (112) may supply hydraulic fluid in the direction in which the agricultural work vehicle (100) moves forward if the angle of the swash plate (210) is greater than the upper limit of the neutral range, and may supply hydraulic fluid in the direction in which the agricultural work vehicle (100) moves backward if the angle of the swash plate (210) is less than the lower limit of the neutral range. In the present disclosure, the swash plate (210) included in the hydraulic pump (112) may be referred to as a 'pump swash plate (210)'.

[0037] The hydraulic motor (114) can be rotated by hydraulic fluid supplied from the hydraulic pump (112). The hydraulic motor (114) can rotate the wheel directly or transmit power to the wheel through a drive system (e.g., gearbox, differential gear, etc.). The speed of the hydraulic motor (114) can be proportional to the flow rate, and the output torque can be proportional to the hydraulic pressure.

[0038] The hydraulic motor (114) may include a swash plate (220). The hydraulic motor (114) may change the output torque and rotational speed according to the angle of the swash plate (220). For example, as the angle of the swash plate (220) increases, the output torque of the hydraulic motor (114) may increase and the rotational speed may decrease, and as the angle of the swash plate (220) decreases, the output torque of the hydraulic motor (114) may decrease and the rotational speed may increase. In the present disclosure, the swash plate (220) included in the hydraulic motor (114) may be referred to as the 'motor swash plate (220)'.

[0039] The angle of the motor swash plate (220) may be a fixed value or adjustable. The hydrostatic transmission (110) may be referred to as a 'general hydrostatic transmission' or a 'single swash plate hydrostatic transmission' when the angle of the motor swash plate (220) is a fixed value, and may be referred to as a 'two-speed hydrostatic transmission' or a 'double swash plate hydrostatic transmission' when the angle of the motor swash plate (220) is adjustable.

[0040] The angle of the pump swash plate (210) can be adjusted by an actuator (120), a link part (130), and a motor (140) for controlling the swash plate.

[0041] The swash plate control motor (140) can generate power to adjust the angle of the pump swash plate (210). The swash plate control motor (140) may be a BLDC (Brushless DC) motor, but is not limited thereto. The swash plate control motor (140) may be implemented to rotate up to 21 degrees, but is not limited thereto.

[0042] The link section (130) can transmit power generated from the swashplate control motor (140) to the actuator (120).

[0043] The actuator (120) can operate the swash plate shaft (230) of the pump swash plate (210) using power received through the link portion (130). The swash plate shaft (230) is a drive shaft coupled to the pump swash plate (210), and when the swash plate shaft (230) operates, the pump swash plate (210) can be tilted.

[0044] As shown in FIG. 2, the actuator (120) may be composed of a cylinder (121), a servo piston (122), a spool (123), and a connecting member (124).

[0045] The cylinder (121) can provide a space for the servo piston (122) to advance or retract. As described below, a space on one side and a space on the other side of the servo piston (122) may be formed inside the cylinder (121). The servo piston (122) can advance or retract due to changes in hydraulic pressure in the space on one side and the space on the other side of the servo piston (122).

[0046] The servo piston (122) can advance or retract due to changes in hydraulic pressure resulting from the linear movement of the spool (123).

[0047] The spool (123) can move in a straight line by the rotational power received through the link portion (130).

[0048] Changes in hydraulic pressure inside the cylinder (121) due to the linear movement of the spool (123), and the forward and backward movement of the servo piston (122) will be described later with reference to FIG. 3.

[0049] The connecting member (124) is installed on the servo piston (122) and can rotate the swash plate shaft (230) according to the forward or backward movement of the servo piston (122). For example, the connecting member (124) may be a dog, but is not limited thereto.

[0050] As shown in FIG. 2, the link portion (130) may be composed of a linkage (131), a rotating member (132), a neutral return axis (133), and a neutral spring (134).

[0051] The rotation axis (141) of the swash plate control motor (140) can be connected to the spool (123) through the rotation member (132) and the linkage (131). The rotation member (132) and the linkage (131) can convert the rotational motion of the swash plate control motor (140) into the linear motion of the linkage (131).

[0052] The rotating member (132) may be provided with one or more eccentric pins. When the swash plate control motor (140) rotates, the rotating member (132) rotates together, and the linkage (131) can move in a straight line (in the up-and-down direction in the example of FIG. 2) by means of one or more eccentric pins. In the example of FIG. 2, when the swash plate control motor (140) rotates counterclockwise, the linkage (131) may rise, and when it rotates clockwise, the linkage (131) may descend, but is not limited thereto.

[0053] One side of the linkage (131) is connected to the rotating member (132) and the other side is connected to the spool (123), so that the spool (123) can be advanced or retracted.

[0054] The rotating member (132) may include a neutral return axis (133).

[0055] The neutral spring (134) can return the rotating member (132) to a neutral position by means of elastic force. One end of the neutral spring (134) may be connected to the housing (240) of the hydrostatic transmission (110), and the other end may be connected to the neutral return shaft (133). The neutral spring (134) may be implemented as a torsion spring, but is not limited thereto. The operation of the neutral spring (134) will be described later with reference to FIGS. 4a, 4b, and 4c.

[0056] Meanwhile, the link portion (130) may be implemented in the form of a reduction gear, and such an example will be described later with reference to FIG. 5.

[0057] The control unit (150) can control the rotation of the swash plate control motor (140) based on the operation state of the HST operation unit (160). For example, the control unit (150) can determine the target angle of the pump swash plate (210) based on the operation state of the HST operation unit (160), and determine the rotation angle of the swash plate control motor (140) based on the determined target angle. The control unit (150) can control the swash plate control motor (140) to rotate by the determined rotation angle.

[0058] To this end, the control unit (150) may include a memory for storing one or more instructions or programs, and a processor for executing one or more instructions or programs stored in the memory.

[0059] The memory may include at least one of flash memory, hard disk, RAM (Random Access Memory), SRAM (Static Random Access Memory), ROM (Read-Only Memory), EEPROM (Electrically Erasable Programmable Read-Only Memory), or PROM (Programmable Read-Only Memory), but is not limited thereto.

[0060] The processor may be composed of at least one of, for example, a CPU (Central Processing Unit), an MCU (Micro Controller Unit), a microprocessor, an AP (Application Processor), a GPU (Graphic Processing Unit), an ASIC (Application Specific Integrated Circuit), or a DSP (Digital Signal Processor), but is not limited thereto.

[0061] For example, the control unit (150) may be at least one of an ECU (Electronic Control Unit), HCU (Hybrid Control Unit), VCU (Vehicle Control Unit), EVCU (Electric Vehicle Control Unit), or TCU (Transmission Control Unit), but is not limited thereto.

[0062] The HST control unit (160) can be operated by a user to control the direction and speed of movement of the agricultural work vehicle. For example, the HST control unit (160) may be a pedal, a lever, or a joystick, but is not limited thereto.

[0063] When the HST operating unit (160) is operated in the forward direction, the control unit (150) can rotate the swash plate control motor (140) in a direction to adjust the angle of the pump swash plate (210) in the forward direction. When the HST operating unit (160) is operated in the backward direction, the control unit (150) can rotate the swash plate control motor (140) in a direction to adjust the angle of the pump swash plate (210) in the backward direction.

[0064] When the HST operating unit (160) is operated to the neutral position, the control unit (150) can rotate the swash plate control motor (140) to the neutral position in a direction to adjust the angle of the pump swash plate (210) to the neutral area. However, in an example where a neutral spring (134) is applied, when the HST operating unit (160) is operated to the neutral position, the control unit (150) does not control the rotation of the swash plate control motor (140), and the swash plate control motor (140) can be in a free state (i.e., a no-load state). The disc (132) can return to the neutral position by the elastic force of the neutral spring (134).

[0065] FIG. 3 is intended to explain the operation of an actuator according to one embodiment.

[0066] Although not illustrated in FIG. 3, the actuator (120) may include a forward path and a backward path. The forward path may be connected to one side space of the servo piston (122) within the cylinder (121) (e.g., the lower space in the example of FIG. 3), and the backward path may be connected to the other side space of the servo piston (122) within the cylinder (121) (e.g., the upper space in the example of FIG. 3).

[0067] When the spool (123) moves in the forward direction, hydraulic fluid is supplied to one side space through the forward flow path, so that the hydraulic pressure can increase, and when the spool (123) moves in the backward direction, hydraulic fluid is supplied to the other side space through the backward flow path, so that the hydraulic pressure can increase. Additionally, when the spool (123) moves in the forward direction, hydraulic fluid from the other side space is discharged through the backward flow path, so that the hydraulic pressure can decrease, and when the spool (123) moves in the backward direction, hydraulic fluid from one side space is discharged through the forward flow path, so that the hydraulic pressure can decrease.

[0068] Figure 310 illustrates the state of the actuator (120) in a neutral state.

[0069] In the neutral state, the linkage (131) and the spool (123) can be positioned in the neutral position, and both the forward and backward passages can be closed so that the hydraulic pressure in one side space and the other side space can be maintained at a constant level. Accordingly, the servo piston (122) and the connecting member (124) can stop in the neutral position. At this time, the hydraulic pressure in one side space and the other side space can be the same.

[0070] Figure 320 illustrates the state of the actuator (120) at the moment when the HST operating part (160) is operated in the forward direction while in a neutral state.

[0071] When the HST operating unit (160) is operated in the forward direction while in the neutral state, the linkage (131) and the spool (123) can move in the forward direction (e.g., upward), and the hydraulic pressure in one side space can rise through the forward path and the hydraulic pressure in the other side space can fall through the backward path. Accordingly, the servo piston (122) and the connecting member (124) can move in the forward direction.

[0072] 330 in FIG. 3 illustrates the state of the actuator (120) in the forward state. The forward state may refer to a state in which the HST operating unit (160) is operated in the forward direction and the operation state is maintained.

[0073] In the forward state, the linkage (131) and spool (123) can stop at a forward position corresponding to the operating state of the HST operating unit (160), and both the forward flow path and the backward flow path can be closed so that the hydraulic pressure in one side space and the other side space can be maintained at a constant level. Accordingly, the servo piston (122) and the connecting member (124) can stop at a forward position corresponding to the operating state of the HST operating unit (160). At this time, the hydraulic pressure in one side space may be greater than the hydraulic pressure in the other side space.

[0074] Figure 340 illustrates the state of the actuator (120) at the moment when the HST operating unit (160) is operated to the neutral position while in the forward state.

[0075] When the HST operating unit (160) is operated to the neutral position while in the forward state, the linkage (131) and spool (123) can move in the neutral direction (e.g., downward), and the hydraulic pressure in one side space can be lowered through the forward path and the hydraulic pressure in the other side space can be raised through the backward path. Accordingly, the servo piston (122) and the connecting member (124) can move in the neutral direction.

[0076] Figure 350 illustrates the state of the actuator (120) in a neutral state.

[0077] In the same manner as 310 in FIG. 3, the linkage (131) and the spool (123) can be positioned in the neutral position, and both the forward and backward passages can be closed so that the hydraulic pressure in one side space and the other side space can be maintained constant. Accordingly, the servo piston (122) and the connecting member (124) can stop in the neutral position. At this time, the hydraulic pressure in one side space and the other side space can be the same.

[0078] Meanwhile, in the case where the HST control unit (160) is operated in the reverse direction while in the neutral state to become reversed and then the HST control unit (160) is operated back to the neutral state, it can operate similarly.

[0079] For example, when the HST operating unit (160) is operated in the reverse direction while in the neutral state, the linkage (131) and spool (123) can move in the retractable direction (e.g., downward), and the hydraulic pressure in one side space can be lowered through the forward path and the hydraulic pressure in the other side space can be raised through the retractable path. Accordingly, the servo piston (122) and the connecting member (124) can move in the retractable direction.

[0080] When the HST operating unit (160) is operated to the neutral position in the reverse state, the linkage (131) and spool (123) can move in the neutral direction (e.g., upward), and the hydraulic pressure in one side space can rise through the forward path and the hydraulic pressure in the other side space can fall through the backward path. Accordingly, the servo piston (122) and the connecting member (124) can move in the neutral direction. The reverse state may refer to a state in which the HST operating unit (160) is operated in the reverse direction and the corresponding operating state is maintained.

[0081] When understood based on the direction of movement of the servo piston (122), the aforementioned operation of the HST operating unit (160) in the forward direction in the neutral state and the operation of the HST operating unit (160) in the neutral state in the reverse state can be understood as the HST operating unit (160) being operated in a direction to advance the servo piston (122).

[0082] When understood based on the direction of movement of the servo piston (122), the aforementioned operation of the HST operating unit (160) to the neutral position in the forward state, and the operation of the HST operating unit (160) to the reverse direction in the neutral state can be understood as the HST operating unit (160) being operated in a direction to retract the servo piston (122).

[0083] FIGS. 4a, 4b, and 4c are intended to illustrate the operation of a neutral spring according to one embodiment.

[0084] FIG. 4a illustrates the relationship between the housing (240), the neutral return axis (133), and the neutral spring (134) in a neutral state.

[0085] FIG. 4b illustrates a state in which the rotating member (132) is rotated clockwise from the neutral position by the control unit (150). When the control unit (150) controls the rotation angle of the swash plate control motor (140) to a specific angle, the torque generated by the swash plate control motor (140) and the elastic force (restoring force) of the neutral spring (134) are in equilibrium, so that the rotating member (132) maintains a state in which it is rotated at a specific angle. In this state, when the user operates the HST operating unit (160) to the neutral position, the control unit (150) leaves the swash plate control motor (140) in a free state, and the rotating member (132) rotates counterclockwise by the elastic force (restoring force) of the neutral spring (134) to return to the neutral position.

[0086] FIG. 4c illustrates a state in which the rotating member (132) is rotated counterclockwise from the neutral position by the control unit (150). When the control unit (150) controls the rotation angle of the swash plate control motor (140) to a specific angle, the torque generated by the swash plate control motor (140) and the elastic force (restoring force) of the neutral spring (134) are in equilibrium, so that the rotating member (132) maintains a state in which it is rotated to a specific angle. In this state, when the user operates the HST control unit (160) to the neutral position, the control unit (150) puts the swash plate control motor (140) in a no-load state, and the rotating member (132) rotates clockwise by the elastic force (restoring force) of the neutral spring (134) to return to the neutral position.

[0087] FIG. 5 is a reference diagram schematically illustrating the structure of a hydrostatic transmission including a reduction gear according to one embodiment.

[0088] In the description regarding Fig. 4, the description of components identical to those in Fig. 2 is omitted.

[0089] As illustrated in FIG. 4, the link portion (130) may be composed of a linkage (131), a first gear (135), and a second gear (136).

[0090] The first gear (135) and the second gear (136) form a reduction gear to reduce the rotational speed of the swash plate control motor (140). The second gear (136) may have a larger diameter than the first gear (135), but is not limited thereto. For example, compared to the embodiment of FIG. 2, a larger rotational angle is allowed for the swash plate control motor (140), so the angle of the pump swash plate (112) can be controlled more precisely.

[0091] The second gear (136) may be equipped with a plurality of eccentric pins. When the swash plate control motor (140) rotates, the first gear (135) and the second gear (136) rotate together, and the linkage (131) can move linearly (in the up-and-down direction in the example of FIG. 4) by means of the plurality of eccentric pins. In the example of FIG. 4, when the swash plate control motor (140) rotates counterclockwise, the linkage (131) may rise, and when it rotates clockwise, the linkage (131) may descend, but is not limited thereto.

[0092] One side of the linkage (131) is connected to the second gear (136) and the other side is connected to the regulator spool (123), so that the regulator spool (123) can be advanced or retracted.

[0093] The embodiments of the present disclosure described above may be implemented in the form of a recording medium comprising computer-executable instructions, such as program modules executed by a computer. A computer-readable medium may include any volatile and non-volatile media, and removable and inseparable media, that can be accessed by a computer. Additionally, a computer-readable medium may include computer storage media and communication media. A computer storage medium may include volatile and non-volatile, removable and inseparable media implemented by any method or technique for storing information, such as computer-readable instructions, data structures, program modules, or other data. A communication medium may include other data of modulated data signals, such as computer-readable instructions, data structures, or program modules.

[0094] The foregoing description of the present disclosure is for illustrative purposes only, and those skilled in the art will understand that other specific forms can be easily modified without altering the technical concept or essential features of the present disclosure. Therefore, all of the above descriptions should be understood as illustrative and not limiting. For example, a component described in a single form may be implemented in a distributed manner, and components described in a distributed manner may likewise be implemented in a combined manner.

[0095] The scope of the present disclosure is defined by the claims set forth below rather than by the detailed description above, and all modifications or variations derived from the meaning and scope of the claims and equivalents thereof should be interpreted as being included within the scope of the present disclosure.

Claims

1. In an agricultural work vehicle (100) equipped with a hydro-static transmission (HST, Hydro-Static Transmission) (110), A hydraulic pump (112) including a pump swash plate (210) and supplying working fluid according to the angle of the pump swash plate (210); A swash plate control motor (140) that generates power to adjust the angle of the pump swash plate (210); An actuator (120) that operates the swash plate shaft (230) of the pump swash plate (210) using power generated from the above swash plate control motor (140); A link portion (130) that transmits power generated from the above-mentioned swashplate control motor (140) to the above-mentioned actuator (120); and A control unit (150) that controls the rotation of the swash plate control motor (140) based on the operation state of the HST control unit (160); An agricultural work vehicle including 2. In Paragraph 1, The above actuator (120) is, A spool (123) that moves in a straight line by rotational power received through the above link part (130), A servo piston (122) that moves forward or backward by a change in hydraulic pressure due to the linear movement of the spool (123), and A cylinder (121) that provides a space for the servo piston (122) to advance or retract, Agricultural work vehicle.

3. In Paragraph 2, The above actuator (120) is, A connecting member (124) further comprising a member installed on the servo piston (122) and rotating the swash plate shaft (230) according to the forward or backward movement of the servo piston (122). Agricultural work vehicle.

4. In Paragraph 3, When the above HST operating unit (160) is operated in a direction to advance the servo piston (122), The above control unit (150) rotates the above swashplate control motor (140) in a first direction, and The above spool (123) moves linearly in a second direction according to the rotation of the above swash plate control motor (140), and The hydraulic pressure in one side space of the servo piston (122) within the cylinder (121) rises, and The hydraulic pressure in the other side space of the servo piston (122) within the cylinder (121) decreases, and The above servo piston (122) advances according to the increase in hydraulic pressure of the one side space and the decrease in hydraulic pressure of the other side space. Agricultural work vehicle.

5. In Paragraph 4, When the above HST operating unit (160) is operated in a direction to retract the servo piston (122), The above control unit (150) rotates the above swashplate control motor (140) in a third direction, and The above spool (123) moves linearly in the fourth direction according to the rotation of the above swash plate control motor (140), and The hydraulic pressure in the one-sided space of the servo piston (122) within the cylinder (121) decreases, and The hydraulic pressure in the other side space of the servo piston (122) within the cylinder (121) rises, and The above servo piston (122) retracts according to the hydraulic pressure decrease in the one-sided space and the hydraulic pressure increase in the other-sided space, and The above third direction is different from the above first direction, and The above fourth direction is different from the above second direction, Agricultural work vehicle.

6. In Paragraph 2, The above link portion (130) is, It includes a rotating member (132) coupled to the rotation axis (141) of the above-mentioned motor (140) for controlling the swash plate, and The above rotating member (132) is, A device comprising one or more eccentric pins that transmit rotational power of the swash plate control motor (140) to the spool (123) so that the spool (123) moves in a straight line. Agricultural work vehicle.

7. In Paragraph 6, The above-mentioned rotating member (132) further includes a neutral return axis (133), and The above link portion (130) is, A neutral spring (134) further comprising one end connected to the housing (240) of the above hydrostatic transmission (110) and the other end connected to the neutral return shaft (133) to return the rotating member (132) to a neutral position by means of elastic force. Agricultural work vehicle.

8. In Paragraph 2, The above link portion (130) is, A first gear (135) coupled to the rotation shaft (141) of the above-mentioned swashplate control motor (140), and It includes a second gear (136) formed by meshing with the first gear (135), and The above second gear (136) is, A device comprising one or more eccentric pins that transmit rotational power of the swash plate control motor (140) to the spool (123) so that the spool (123) moves in a straight line. Agricultural work vehicle.

9. In Paragraph 8, The second gear (136) has a larger diameter than the first gear (135). agricultural work vehicle 10. In Paragraph 8, The above second gear (136) further includes a neutral return shaft (137), and The above link portion (130) is, A neutral spring (134) further comprising one end connected to the housing (240) of the above hydrostatic transmission (110) and the other end connected to the neutral return shaft (137) to return the second gear (136) to a neutral position by means of elastic force. Agricultural work vehicle.

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