Background Art Conventionally, an overhead power line is manually installed or replaced by a worker.

When the overhead power line is installed or replaced in a predetermined line area, a plurality of workers are required. The workers are located on the ground and a pole. The ground worker suspends the power line with rope and then gives the pole worker the power line suspended with the rope. The pole worker pulls up the power line suspended with the rope and then fixes the power line to an insulator of a pole arm. As described above, the ground and pole workers install and replace the overhead power line by moving it from the ground to the pole.

Where the overhead power line is installed or replaced by the ground and pole workers, the efficiency of the work may be deteriorated and the installation and replacement work may endanger the safety of the ground and pole workers. Further, where the overhead power line is installed or replaced by the ground and pole workers, many workers are required. In order to address these problems described above, several techniques have been proposed.

Among the proposed techniques, there are Korean Patent Application Ser. No. 1999-18716 entitled"APPARATUS FOR INSTALLING POWER LINE", filed in the Korean Industrial Property Office on May 24,1999 by the applicant of the present invention and issued to the applicant; and Korean Patent Application Ser. No. 1999-16932 entitled"APPARATUS FOR INSTALLING OVERHEAD POWER LINE", filed in the Korean Industrial Property Office on June 14,2000 by the applicant of the present invention and issued to the applicant.

The apparatus disclosed in Korean Patent Application Ser. No. 1999-18716 or 1999-16932 can effectively improve the work of the power line installation by preventing the power line from being damaged because a power line is not in contact with the ground when the power line is transferred for the power line installation. The safety of a worker can be secured and the installation work can

rapidly progress. Further, costs required to install the power line can be reduced.

An inventor of the present invention has developed an apparatus for installing an overhead power line, which can constantly maintain a linear velocity between power line bobbins by synchronizing a linear velocity of one power line bobbin with that of the other power line bobbin.

Disclosure of the Invention Therefore, the present invention has been made in view of the above problems, and it is an object of the present invention to provide an apparatus for installing an overhead power line, which can constantly maintain a linear velocity between line bobbins by synchronizing a linear velocity of one power line bobbin with that of the other power line bobbin.

It is another object of the present invention to provide an apparatus for installing an overhead power line, which can maintain a predetermined linear velocity when the power line of a power line bobbin is wound or unwound by detecting a physical quantity relating to the linear velocity and processing a predetermined operation based on a detected signal.

In accordance with an aspect of the present invention, the above and other objects can be accomplished by the provision of an apparatus for installing an overhead power line, the apparatus including a hydraulic pump driven by an engine, an oil control valve coupled to a central oil passage for controlling the driving of a hydraulic motor, the hydraulic motor for rotating driving rollers corresponding to a bobbin driver in a normal direction and the driving rollers for rotating and driving a power line bobbin unit on which the power line is wound, the apparatus being mounted on a vehicle, comprising: a hydraulic motor control unit including: a detector for detecting a physical quantity relating to a linear velocity when the power line is wound or unwound on the power line bobbin unit and outputting an electrical signal corresponding to the physical quantity; a controller for receiving the electrical signal from the detector, processing a predetermined operation based on the received signal, outputting an oil amount control signal to the oil control valve so that a predetermined linear velocity can be constantly maintained when the power line is wound or unwound on the power line bobbin unit, and controlling a rotation

velocity of the hydraulic motor ; and a transceiver for receiving and transmitting a set value of the linear velocity from and to another overhead power line installation apparatus on which another power line bobbin unit is mounted, another power line bobbin unit taking an end of the power line being wound.

Preferably, the hydraulic motor control unit may further include an A/D (Analog/Digital) converter for converting an analog signal detected by the detector into a digital signal; and a D/A (Digital/Analog) converter for converting a digital oil amount control signal outputted from the controller into an analog signal.

Preferably, the hydraulic motor control unit may further include a memory for storing a data table for an oil amount control signal corresponding to the signal detected by the detector, and the controller may read the oil amount control signal corresponding to the signal detected by the detector from the data table of the memory and output the oil amount control signal toward the oil control valve.

Preferably, the hydraulic motor control unit may further include a key input module for receiving a key input so that the linear velocity can be set and constantly maintained by the controller; and a key encoder for receiving a key input signal inputted from

the key input module, converting the key input signal and outputting the converted signal to the controller, and the memory may further store the set value of the linear velocity set by the key input module.

Preferably the hydraulic motor control unit may further include an LED (Light Emitting Diode) display module for displaying predetermined characters in response to an output of the controller; and a display driver for driving an output of the LED display module.

Brief Description of the Drawings The above and other objects, features and other advantages of the present invention will be more clearly understood from the following detailed description taken in conjunction with the accompanying drawings, in which: Fig. 1 is an exemplary view illustrating apparatuses for installing an overhead power line in accordance with the present invention; and Fig. 2 is an exemplary block diagram illustrating a hydraulic motor controller included in each apparatus of Fig. 1 in accordance with the present invention.

Best Mode for Carrying Out the Invention

Preferred embodiments of the present invention will be described in detail with reference to the annexed drawings so that the present invention can be readily understood and reproduced.

The present invention incorporates Korean Patent Application Ser. No. 1999-18716 filed in the Korean Industrial Property Office on May 24,1999 by the applicant of the present invention and issued to the applicant ; and Korean Patent Application Ser. No. 1999- 16932 filed in the Korean Industrial Property Office on June 14, 2000 by the applicant of the present invention and issued to the applicant. Because a mechanical structure included in an apparatus for installing an overhead power line in accordance with the present invention is disclosed in Korean Patent Application Ser.

Nos. 1999-18716 and 1999-16932, a detailed description of the mechanical structure will be omitted in this specification.

Fig. 1 is an exemplary view illustrating apparatuses for installing an overhead power line in accordance with the present invention.

Each overhead power line installation apparatus includes an engine 10, a decelerator 20, a hydraulic pump 30, an oil control valve 40, a hydraulic motor 50, driving rollers 60 and a hydraulic motor control unit 70.

The engine 10 outputs a driving power to drive the hydraulic motor 50.

The decelerator 20 decelerates the output of the engine 10.

The hydraulic pump 30 is driven by the decelerated output from the decelerator 20.

The oil control valve 40 is coupled to a central oil passage and controls the driving of the hydraulic motor 50.

The hydraulic motor 50 rotates the driving rollers 60 corresponding to a power-line bobbin driver in a normal direction.

The driving rollers 60 rotate and drive a power line bobbin 100 on which the power line 200 is wound.

The hydraulic motor control unit 70 outputs an oil amount control signal to the oil control valve 40 so that the apparatus is synchronized with another overhead power line installation apparatus and therefore the linear velocity of power line bobbin units between two apparatuses can be constantly maintained.

When the power line 200 is installed between two poles (not shown) spaced by a predetermined distance, two vehicles are disposed at locations of the two poles.

Each overhead power line installation apparatus is mounted on one vehicle. Where a pre-existing power line

coupled to the two poles is replaced with a new power line being the power line 200, an end of the pre-existing power line is coupled to an end of the power line 200 of the power line bobbin 100 mounted on one vehicle and the other end of the pre-existing power line is coupled to the other end of the power line 200 of another power line bobbin 100 mounted on the other vehicle. Thereafter, the pre-existing power line is replaced with the power line 200 along pulleys 300 arranged on pole arms (not shown) of the two poles.

On the other hand, where the power line 200 is installed between two poles by a power line installation work in a state where no power line is installed between the two poles, the power line 200 is unwound from the power line bobbin 100 mounted. on one vehicle located at one pole. The power line 200 is inserted into a pulley 300 installed on a pole arm of the one pole and then inserted into another pulley 300 installed on another pole arm of the other pole. Thereafter, the power line 200 inserted into another pulley 300 is coupled to another power line bobbin 100 mounted on the other vehicle located at the other pole. As described above, the power line 200 is installed between the two poles.

When the power line 200 is installed between the poles by the above-described method, the power line 200

may be wound in one direction or the power line 200 installed between the poles may droop by gravity. To correct this situation, the power line bobbins 100 are rotated in different directions. At this time, the linear velocity at which the power line 200 is wound or unwound on the power line bobbins 100 should be constantly maintained. However, the linear velocity between the power line bobbins 100 may not be constantly maintained and therefore an error may occur.

So, the overhead power line installation apparatuses mounted on the two vehicles should be synchronized so that the linear velocity between the power line bobbins 100 of the two apparatuses can be constantly maintained according to a radius of rotation varying with the winding or unwinding of the power line 200 of the power line bobbins 100. If so, the power line 200 can be smoothly installed between the poles.

In the overhead power line installation apparatus in accordance with present invention, the hydraulic pump 30 is driven by a decelerated output from the decelerator 20 after it decelerates an output of the engine 10. The driving rollers 60 are rotated in the normal direction by the oil control valve 40 coupled to the central oil passage and therefore the power line bobbin 100 is rotated and driven in the normal direction. The

hydraulic motor control unit 70 outputs the oil amount control signal to the oil control valve 40 so that the overhead power line installation apparatuses are synchronized and therefore the linear velocity of the power line 200 being wound or unwound on the power line bobbin units supported by the two apparatuses located at the spaced poles is constantly maintained. The hydraulic motor control unit 70 controls the rotation of the driving rollers 60 being rotated and driven by the oil control valve 40.

In more detail, one of the two overhead power line installation apparatuses winding or unwinding the power line 200 sets a value of an appropriate linear velocity.

The one overhead power line installation apparatus transmits the set linear velocity value to the other overhead power line installation apparatus so that the other overhead power line installation apparatus employs the set linear velocity value to be synchronized with the one overhead power line installation apparatus.

Thereafter, each overhead power line installation apparatus controls the linear velocity by detecting the physical quantity relating to the linear velocity of the power line 200 being wound or unwound and processing the predetermined operation based on a result of the detection.

Fig. 2 is an exemplary block diagram illustrating the hydraulic motor control unit 70 included in each apparatus of Fig. 1 in accordance with the present invention.

The hydraulic motor control unit 70 in accordance with the present invention includes a detector 71, a controller 72, a transceiver 73, an A/D (Analog/Digital) converter 74, a D/A (Digital/Analog) converter 75, a memory 76, a key input module 77, a key encoder 78, an LED (Light Emitting Diode) display module 79 and a display driver 80.

The detector 71 detects a physical quantity relating to a linear velocity when the power line 200 is wound or unwound on a power line bobbin unit and then outputs an electrical signal corresponding to the physical quantity.

The following Equation 1 and Equation 2 show the linear velocity and an angular velocity in a principle of rotation dynamics, respectively.

Equation 1 In Equation 1, "v", "T" and "r" denote the linear velocity, a periodic time (seconds) and a radius,

respectively.

Equation 2 # 2# #= t = T In Equation 2,"w","t"and"@"denote the angular velocity, a time (seconds) and a rotation angle, respectively.

The following Equation 3 shows a relationship between the linear velocity of Equation 1 and the angular velocity of Equation 2.

Equation 3 v=r (o As apparent from the above-described Equation 1, Equation 2 and Equation 3, a rotation velocity of the power line bobbin 100 should be controlled according to a radius of rotation varying with the winding or unwinding of the power line 200 on the power line bobbin 100 so that the linear velocity of the power line 200 can be constantly maintained.

However, the linear velocity between the power line bobbins 100 may not be constantly maintained in the power line installation work and therefore an error may occur.

The hydraulic motor control unit 70 controls the rotation

velocity of the power line bobbin 100 so that the error can be removed.

Thus, the overhead power line installation in accordance with the present invention detects the physical quantity relating to the linear velocity of the power line bobbin 100 and then outputs the electrical signal corresponding to the physical quantity in order to control the physical quantity relating to the linear velocity of the power line bobbin 100 through the detector 71.

In more detail, the detector 71 can be implemented as a torque sensor, which detects a rotation torque of the power line bobbin unit representing the physical quantity relating to the linear velocity of the power line 200 and outputs a result of the detection.

The rotation torque represents the physical quantity reflecting the linear velocity irrespective of a remaining amount of the power line 200 wound on the power line bobbin 100, that is, a radius"r".

The torque sensor preferably detects the rotation torque around a rotation axis of the power line bobbin 100.

Further, the detector 71 can be implemented as a torque sensor, which detects a tension of a chain 61 coupled between two driving rollers 60 rotating and

driving the power line bobbin unit, and outputs a result of the detection.

The tension is proportional to the rotation torque and reflects the linear velocity when the power line 200 is wound and unwound.

The tension sensor is arranged between the hydraulic motor 50 and a driving roller 60 so that the tension between them can be detected.

Furthermore, the detector 71 can be implemented as an oil pressure sensor, which detects the pressure of oil from the oil control valve 40 and then outputs a result of detection.

The pressure of oil from the oil control valve 40 represents the physical quantity, which can be employed to control the rotation velocity of the hydraulic motor 50, and is associated with the linear velocity when the power line 200 is wound and unwound.

The detector 71 is a generic sensor, which can detect any physical quantity capable of mathematically deriving the linear velocity.

The controller 72 controls the entire hydraulic motor control unit 70 and receives an output signal from the detector 71. The controller 72 processes a predetermined operation based on the received signal, outputs an oil amount control signal to the oil control

valve 40 so that a predetermined linear velocity can be constantly maintained when the power line is wound or unwound on the power line bobbin unit, and controls a rotation velocity of the hydraulic motor 50.

In other words, the controller 72 controlling the entire hydraulic motor control unit 70 receives an . electrical signal from the detector 71 and processes the predetermined operation based on the received signal.

The controller 72 can process a different operation according to a type of the physical quantity. The operation can be processed in software or hardware, which can derive the linear velocity from the detected physical quantity.

The controller 72 compares the linear velocity produced by the operation with a reference linear velocity, outputs the oil amount control signal corresponding to a result of the comparison to the oil control valve 40, and then controls the rotation velocity of the hydraulic motor 50, wherein the result of the comparison includes a difference between the linear velocity produced by the operation and the reference linear velocity. Accordingly, the linear velocity can be constantly maintained when the power line is wound or unwound on the power line bobbin unit.

The transceiver 73 receives and transmits a set

value of the linear velocity from and to another overhead power line installation apparatus on which another power line bobbin unit taking an end of the power line 200 being wound is mounted.

The transceiver 73 preferably performs local-area radio communication of an RF' (Radio Frequency) signal type between the two overhead power line installation apparatuses spaced each other.

If the overhead power line installation apparatus sets a value of a proper linear velocity, the transceiver 73 transmits the value of the proper linear velocity to another overhead power line installation apparatus in order to synchronize the overhead power line installation apparatus with another overhead power line installation apparatus, that is, in order to constantly maintain the linear velocity between the two overhead power line installation apparatuses. Thereafter, the controller 72 processes the predetermined operation so that the set linear velocity can be maintained according to a result of the detection of the physical quantity, outputs the oil amount control signal to the oil control valve 40, and controls the rotation velocity of the hydraulic motor 50.

The A/D converter 74 converts an analog signal detected by the detector 71 into a digital signal and

then outputs the digital signal.

In other words, where a sensor detecting the analog signal is adopted as the detector 71 detecting the physical quantity relating to the linear velocity of the power line bobbin 100, the A/D converter 74 converts the analog signal into the digital signal so that the controller 72 can appropriately process the analog signal.

The D/A converter 75 converts a digital oil amount control signal outputted from the controller 72 into an analog signal.

In other words, where the controller 72 processes the operation corresponding to the detected physical quantity relating to the linear velocity of the power line bobbin 100 and outputs the oil amount control signal based on the digital signal, the D/A converter 75 outputs the analog signal to control the oil control valve 40.

The memory 76 stores a data table for the oil amount control signal corresponding to the signal detected by the detector 71.

At this time, the controller 72 reads the oil amount control signal corresponding to the signal detected by the detector 71 from the data table of the memory 76 and outputs the oil amount control signal toward the oil control valve 40.

The memory 76 stores oil amount control signals corresponding to reference linear velocities set from a result of the operation by the controller 72 in the data table. The controller 72 reads a corresponding oil amount control signal based on the result of the operation, outputs the oil amount control signal to the oil control valve 40, and controls the rotation velocity of the hydraulic motor 50 so that a predetermined linear velocity can be constantly maintained when the power line 200 is wound or unwound on the power line bobbin unit.

The memory 76 can further store a set value of the linear velocity.

In other words, the memory 76 further stores the set value of the linear velocity as the reference linear velocity so that the linear velocity produced by the controller 72 can be compared the reference linear velocity.

The key input module 77 receives a key input so that the linear velocity can be set and constantly maintained by the controller 72.

In other words, the key input module 77 receives a control command input so that the linear velocity can be set and constantly maintained by the controller 72.

The key encoder 78 receives a key input signal inputted from the key input module 77, converts the key

input signal into an electrical signal and outputs the converted signal to the controller 72.

In other words, the key encoder 78 receives the control command inputted from the key input module 77, converts the control command into an electrical signal and outputs the converted signal to the controller 72.

The LED display module 79 displays predetermined characters in response to an output of the controller 72.

In. other words, the LED display module 79 displays the predetermined characters representing the set value of the linear velocity in response to the control of the controller 72.

The display driver 80 drives an output of the LED display module 79.

The overhead power line installation apparatus in accordance with the present invention allows the detector 71 to detect a physical quantity relating to the linear velocity when the power line 200 is wound or unwound on a power line bobbin unit and output an electrical signal corresponding to the physical quantity. The overhead power line installation apparatus allows the controller 72 to receive the electrical signal from the detector71, process the predetermined operation based on the received signal, output an oil amount control signal to the oil control valve 40 so that a predetermined linear velocity

can be constantly maintained when the power line is wound or unwound on the power line bobbin unit, and control a rotation velocity of the hydraulic motor 50.

The overhead power line installation apparatus in accordance with the present invention allows the transceiver 73 to receive and transmit a set value of the linear velocity from and to another overhead power line installation apparatus on which another power line bobbin unit taking an end of the power line being wound is mounted. The overhead power line installation apparatus allows the controller 72 to process the predetermined operation so that a set linear velocity can be maintained according to a result of the detection of the physical quantity, output the oil amount control signal to the oil control valve 40, and control the rotation velocity of the hydraulic motor 50.

The overhead power line installation apparatus in accordance with the present invention allows the A/D converter 74 to convert an analog signal detected by the detector 71 into a digital signal, and allows the D/A converter 75 to convert a digital oil amount control signal outputted from the controller 72 into an analog signal.

The overhead power line installation apparatus in

accordance with the present invention allows the memory 76 to store a data table for an oil amount control signal corresponding to the signal detected by the detector 71, and allows the controller 72 to read the oil amount control signal corresponding to the signal detected by the detector 71 from the data table of the memory 76 and output the oil amount control signal toward the oil control valve 40.

The overhead power line installation apparatus in accordance with the present invention allows the key input module 77 to receive a control command, allows the key encoder 78 to receive a key input signal inputted from the key input module 77, convert the key input signal and output the converted signal to the controller 72, and allows the LED display module 79 driven by the display driver 80 to display predetermined characters in response to an output of the controller 72.

Accordingly, the object of an overhead power line installation apparatus in accordance with the present invention can be accomplished.

Industrial Applicability As apparent from the above description, the present invention provides the overhead power line installation

apparatus, which can constantly maintain a predetermined linear velocity by detecting a physical quantity relating to a linear velocity when a power line is wound or unwound on a power line bobbin unit and processing a predetermined operation based on a detection signal. The overhead power line installation apparatus can receive a set value of the linear velocity from another overhead power line installation apparatus. As a result, the overhead power line installation apparatus can be synchronized with another overhead power line installation apparatus and therefore the linear velocity between the two apparatuses can be constantly maintained Although the present invention has been described in connection with specific preferred embodiments, those skilled in the art will appreciate that various modifications, additions, and substitutions to the specific elements are possible, without departing from the scope and spirit of the present invention as disclosed in the accompanying claims.