JP2021042015A - crane - Google Patents

Abstract

To provide a crane capable of preventing the deterioration of power transmission efficiency when supplying electric power to a hook part via a wire rope.SOLUTION: A power supply system 90 comprises a power transmission circuit 92 to convert a DC power to an AC power, a power transmission unit 93 to transmit the AC power to a wire rope 32, a power receiving unit 95 to receive the AC power from the wire rope 32, and a power receiving circuit 96 to convert the received AC power to the DC power. The reactance component of the power supply system 90 is reduced by providing a capacitor 100 in at least one of the power transmission circuit 92 and the power receiving circuit 96. Or, the reactance component of the power supply system 90 is reduced by providing the capacitor 100 in at least one of the power transmission circuit 92, the power receiving circuit 96, and compensation circuits 104, 105 which are adjacent to the power transmission unit 93 or power receiving unit 95 and through which induced current flows.SELECTED DRAWING: Figure 7

Description

The present invention relates to a crane. More specifically, the present invention relates to a crane capable of preventing deterioration of power transmission efficiency when supplying electric power to a hook portion via a wire rope.

Conventionally, cranes such as mobile cranes, overhead cranes, and gantry cranes have been known. The crane is equipped with a wire rope and a hook portion so that the crane can carry the load in a suspended state.

By the way, Patent Document 1 discloses a crane that supplies electric power to a hook portion via a wire rope. Such a crane transmits AC power via a wire rope from a power transmitting unit provided near the tip of the boom to a power receiving unit provided near the hook portion. However, in such cranes, the inductive reactance in the wire rope caused the transmission efficiency to deteriorate. In particular, in a large crane, the length of the wire rope from the tip of the boom to the hook may increase, resulting in a greater deterioration in power transmission efficiency. Therefore, there has been a demand for a crane capable of preventing deterioration of power transmission efficiency when supplying electric power to the hook portion via a wire rope.

JP-A-2018-193235

Provided is a crane capable of preventing deterioration of power transmission efficiency when supplying electric power to a hook portion via a wire rope.

The first invention is
A crane equipped with a power supply system that supplies power to the hook via a wire rope.
The power supply system
A power transmission circuit that converts DC power to AC power,
A power transmission unit that transmits AC power to the wire rope,
A power receiving unit that receives AC power from the wire rope and
It is equipped with a power receiving circuit that converts the received AC power into DC power.
A capacitor is provided in at least one of the power transmission circuit and the power reception circuit to reduce the reactance component in the power supply system, or
A capacitor is provided in at least one of the power transmission circuit, the power reception circuit, and the power transmission unit or a correction circuit in which an induced current flows adjacent to the power reception unit to reduce the reactance component in the power supply system. is there.

The second invention is the crane according to the first invention.
Calculate the length of the wire rope in the power supply system
The capacitance of the capacitor is changed so as to cancel the inductive reactance in the wire rope that increases with the length of the wire rope.

The third invention is the crane according to the second invention.
With multiple capacitors
By selecting one or more of the capacitors and energizing them, the capacitance of the capacitors is changed.

The fourth invention is the crane according to any one of the first to third inventions.
When the correction circuit provided with the capacitor is provided,
A transformer including the power transmission unit or the power reception unit is provided.
An induced current flows through the correction circuit through the transformer.

In the crane according to the first invention, a capacitor is provided in at least one of the power transmission circuit and the power reception circuit to reduce the reactance component in the power supply system, or in the power transmission circuit and the power reception circuit and the power transmission unit or the power reception unit. A capacitor is provided in at least one of the correction circuits in which the induced current flows adjacently to reduce the reactance component in the power supply system. According to such a crane, it is possible to prevent deterioration of power transmission efficiency when power is supplied to the hook portion via a wire rope.

The crane according to the second invention calculates the length of the wire rope in the power supply system and changes the capacitance of the capacitor so as to cancel the inductive reactance in the wire rope that increases with the length of the wire rope. .. According to such a crane, even if the length of the wire rope is changed due to the winding or unwinding of the wire rope, it is possible to prevent deterioration of the power transmission efficiency when supplying power to the hook portion via the wire rope.

The crane according to the third invention is provided with a plurality of capacitors, and one or a plurality of capacitors are selected to be energized to change the capacitance of the capacitors. According to such a crane, the capacitance can be finely and widely changed by the combination of capacitors. Therefore, even if the length of the wire rope changes due to the winding or unwinding of the wire rope, it is possible to prevent the transmission efficiency from deteriorating when the electric power is supplied to the hook portion via the wire rope.

When the crane according to the fourth invention is provided with a correction circuit provided with a capacitor, the crane includes a transformer including a power transmission unit or a power reception unit, and an induced current flows through the correction circuit through the transformer. According to such a crane, the transformer converts the impedance in the correction circuit. Therefore, since the choice of capacitance is increased, it becomes easy to provide a capacitor having an optimum capacitance.

The figure which shows the crane. The figure which shows the tip of the boom. The figure which shows the control composition of a crane. The figure which shows the power supply system in a crane. The figure which shows the closed circuit in the power supply system. The figure which shows the arrangement of the power transmission part and the power receiving part in a closed circuit. The figure which shows each circuit which constitutes a power supply system. The figure which shows the relationship between the electric circuit length which is a closed circuit length, reactance component, inductive reactance, and capacitive reactance. The figure which shows each circuit which constitutes a power supply system.

The technical idea disclosed in the present application can be applied to other embodiments in addition to the embodiments described below.

First, the crane 1 will be described with reference to FIGS. 1 and 2. In the present embodiment, the crane 1 will be described as a mobile crane, but it can also be applied to other types of cranes provided with a wire rope to which a hook portion is attached. For example, other types of cranes are overhead cranes and gantry cranes.

The crane 1 is mainly composed of a traveling body 2 and a swivel body 3.

The traveling body 2 includes a pair of left and right front wheels 21 and rear wheels 22. Further, the traveling body 2 is provided with an outrigger 23 that is grounded for stability when the load W is transported. The traveling body 2 has an actuator that allows the swivel body 3 supported on the upper portion to be swiveled.

The swivel body 3 is provided with a boom 31 so as to project forward from the rear portion. Therefore, the boom 31 can be swiveled by an actuator (see arrow A). Further, the boom 31 is expandable and contractible by an actuator (see arrow B). Further, the boom 31 is undulated by an actuator (see arrow C).

In addition, a wire rope 32 is bridged over the boom 31. A hook portion 34 is attached to the wire rope 32 hanging from the boom head 33. A winch 35 is provided in the vicinity of the base end side of the boom 31. The winch 35 is integrally configured with the actuator, and enables the wire rope 32 to be taken in and out. Therefore, the hook portion 34 can be raised and lowered (see arrow D).

The boom head 33 is provided with a top sheave 37. Further, the hook portion 34 is provided with a hook sheave 38. A wire rope 32 is wound around the top sheave 37 and the hook sheave 38 (see FIG. 2).

In addition, an overwinding prevention device 39 is attached to the boom head 33. The overwinding prevention device 39 has an overwinding weight 40 suspended from the boom head 33. The overwinding weight 40 has a hollow cylindrical shape, and a wire rope 32 is passed through the hollow portion. When the hook portion 34 comes into contact with the overwinding weight 40 due to the winding of the wire rope 32, the wire 41 is loosened and the overwinding switch 42 is turned on. When the overwinding switch 42 is turned on, the winding of the wire rope 32 is automatically stopped.

Next, the control configuration of the crane 1 will be described with reference to FIG.

The crane 1 includes a controller 4. Various operating tools 51 to 54 are connected to the controller 4. Further, various valves 61 to 64 are connected to the controller 4. Further, various sensors 81 to 84 are connected to the controller 4.

As described above, the boom 31 is rotatable by an actuator (see arrow A in FIG. 1). In the present application, such an actuator is defined as a swivel hydraulic motor 71 (see FIG. 1). The swivel hydraulic motor 71 is appropriately operated by the swivel valve 61, which is a directional control valve. That is, the swivel hydraulic motor 71 is appropriately operated by switching the flow direction of the hydraulic oil by the swivel valve 61. The swivel valve 61 is operated based on the operation of the swivel operating tool 51 by the operator. Further, the turning angle of the boom 31 is detected by the turning sensor 81. Therefore, the controller 4 can recognize the turning angle of the boom 31.

Further, as described above, the boom 31 is expandable and contractible by an actuator (see arrow B in FIG. 1). In the present application, such an actuator is defined as a telescopic hydraulic cylinder 72 (see FIG. 1). The expansion / contraction hydraulic cylinder 72 is appropriately operated by the expansion / contraction valve 62 which is a directional control valve. That is, the expansion / contraction hydraulic cylinder 72 is appropriately operated by the expansion / contraction valve 62 switching the flow direction of the hydraulic oil. The expansion / contraction valve 62 is operated based on the operation of the expansion / contraction operation tool 52 by the operator. Further, the expansion / contraction length of the boom 31 is detected by the expansion / contraction sensor 82. Therefore, the controller 4 can recognize the expansion / contraction length of the boom 31 (hereinafter referred to as “boom length L” (see FIG. 1)).

Further, as described above, the boom 31 is undulated by the actuator (see arrow C in FIG. 1). In the present application, such an actuator is defined as an undulating hydraulic cylinder 73 (see FIG. 1). The undulating hydraulic cylinder 73 is appropriately operated by the undulating valve 63, which is a directional control valve. That is, the undulating hydraulic cylinder 73 is appropriately operated by the undulating valve 63 switching the flow direction of the hydraulic oil. The undulation valve 63 is operated based on the operation of the undulation operation tool 53 by the operator. Further, the undulation angle of the boom 31 is detected by the undulation sensor 83. Therefore, the controller 4 can recognize the undulation angle of the boom 31.

In addition, as described above, the hook portion 34 is movable up and down by an actuator (see arrow D in FIG. 1). In the present application, such an actuator is defined as a winding hydraulic motor 74 (see FIG. 1). The winding hydraulic motor 74 is appropriately operated by the winding valve 64, which is a directional control valve. That is, the winding hydraulic motor 74 is appropriately operated by the winding valve 64 switching the flow direction of the hydraulic oil. The winding valve 64 is operated based on the operation of the winding operation tool 54 by the operator. Further, the unwinding length of the wire rope 32 is detected by the winding sensor 84. Therefore, the controller 4 can recognize the unwinding length of the wire rope 32 (hereinafter, referred to as “wire length” (not shown)).

Next, the power supply system 90 included in the crane 1 will be described with reference to FIGS. 4 to 6. The power supply system 90 supplies power to the hook portion 34 via the wire rope 32. Here, it is assumed that the hook portion 34 is provided with the electric device 97. The electric device 97 is, for example, a camera, sensors, an IMU, or the like.

In addition to the wire rope 32, the power supply system 90 includes a battery 91, a power transmission circuit 92, a power transmission unit 93, a power reception unit 95, and a power reception circuit 96.

As described above, the wire rope 32, which is a conductor, is wound around the top sheave 37 and the hook sheave 38, and electrically constitutes one closed circuit. In the present application, such a closed circuit is referred to as an electric circuit 94.

Specifically, the electric wire 94 is wound around the plurality of top sheaves 37 inserted through the sheave pins 44 and the plurality of hook sheaves 38 inserted through the sheave pins 45 multiple times (six hooks in FIG. 6). .. In such a configuration, the wire rope 32 constitutes a closed circuit via the rope end 102, the boom 31, and the winch 35.

The battery 91 serves as a power source for the power supply system 90. The battery 91 is a power supply device provided in the swivel body 3 (see FIG. 1). The battery 91 is connected to the power transmission circuit 92 and transmits DC power to the power transmission circuit 92.

The power transmission circuit 92 converts DC power into AC power. The power transmission circuit 92 is provided in the boom head 33. The power transmission circuit 92 is connected to the power transmission unit 93 and transmits AC power to the power transmission unit 93.

The power transmission unit 93 transmits AC power to the wire rope 32. The power transmission unit 93 is provided in the vicinity of the boom head 33. The power transmission unit 93 refers to a coil portion wound around the core of the transformer 98 through which the wire rope 32 is passed. The overwinding weight 40 (see FIG. 2) can be used as the core of the transformer 98.

The power receiving unit 95 receives AC power from the wire rope 32. The power receiving unit 95 is provided in the vicinity of the hook unit 34. The power receiving unit 95 refers to a coil portion wound around the core of the transformer 99 through which the wire rope 32 is passed. The power receiving unit 95 is connected to the power receiving circuit 96, and transmits the received AC power to the power receiving circuit 96.

The power receiving circuit 96 converts AC power into DC power. The power receiving circuit 96 is provided in the hook portion 34. The power receiving circuit 96 is connected to the electric device 97 provided in the hook portion 34, and transmits DC power to the electric device 97.

The power transmission unit 93 and the power reception unit 95 are provided on the wire rope 32 having the same number of turns (see FIG. 6). In other words, the power transmitting unit 93 and the power receiving unit 95 are provided on the wire rope 32 extending from the top sheave 37 to the hook sheave 38. In this way, by providing the top sheave 37 or the hook sheave 38 so as not to intervene between the power transmission unit 93 and the power reception unit 95, it is possible to reduce the power transmission loss and improve the power transmission efficiency.

Next, the power supply system 90 will be described in detail with reference to FIGS. 7 and 8. In FIG. 7, the conversion from DC power to AC power and the conversion from AC power to DC power are omitted.

The power supply system 90 is provided with a capacitor 100. The capacitor 100 reduces the reactance component in the power supply system 90. The capacitor 100 is provided in at least one of the power transmission circuit 92 and the power reception circuit 96. Alternatively, the capacitor 100 is provided in at least one of the power transmission circuit 92, the power reception circuit 96, and the correction circuits 104 and 105 (see FIG. 9) described later.

The capacitor 100 is electrically equivalent when it is provided in the power transmission circuit 92 and when it is provided in the power reception circuit 96. Therefore, in the following, the case where the capacitor 100 is mainly provided in the power transmission circuit 92 will be described.

The power transmission circuit 92 is provided with one capacitor 100 (see (A) in FIG. 7). However, a plurality of capacitors 100 may be provided in parallel (see (B) in FIG. 7). When a plurality of capacitors 100 are provided in parallel, an energization switch 101 is connected in series with each of the capacitors 100. The controller 4 can select one or a plurality of capacitors 100 to be energized by switching the energization switch 101 on and off. Thereby, the total capacitance of the capacitor 100 can be changed. It should be noted that the capacitance is not changed by selecting one or a plurality of capacitors 100 and energizing them, but the capacitance may be changed by using a variable capacitor such as a variable capacitor.

Next, control of the energized state of the capacitor 100 according to the length of the electric circuit 94 (hereinafter, referred to as “electric circuit length L _{loop”) will be described.} In the following, the wire rope 32 will be described as an electric path 94, but strictly speaking, the top sheave 37 (see FIG. 6), the hook sheave 38 (see FIG. 6), the transformer 98/99, the winch 35, and the cord end 102 (see FIG. 6). The electric line 94 is composed of elements such as (see).

The electric circuit length L _loop is calculated based on the following equation 1 using the wire length x, the boom length L, and the multiplication number N of the wire rope 32 (hereinafter, referred to as “multiplication number N”). The wire length x is detected by the winding sensor 84 (see FIG. 3). The boom length L is detected by the expansion / contraction sensor 82 (see FIG. 3). The number of hooks N is the number of wire ropes 32 between the tip of the boom 31 and the hook portion 34 (N = 6 in FIG. 6).

In Equation 1, the length of the wire rope 32 that reciprocates between the tip of the boom 31 and the hook portion 34 is set by subtracting the boom length L from the wire length x. Further, the length of the wire rope 32 is divided by the number N to obtain the distance between the tip portion of the boom 31 and the hook portion 34. Then, by doubling the distance between the tip portion of the boom 31 and the hook portion 34, the electric path length L _loop, which is the length of the electric path 94, is calculated.

When the frequency ω of AC power (hereinafter referred to as “frequency ω”) is low, the parallel resistance can be ignored. _{Therefore, the impedance Z ch} of the wire rope 32 when the energization switch 103 is turned off can be approximated by the following equation 2 using the series resistance R _w , the frequency ω, the inductance L _w , and the capacitance C _w.

If the inductance of the transformer 98/99 can be ignored as the electric circuit length L _{loop becomes longer, the inductance L w} can be simplified by the following equation 3 using the _{electric circuit length L loop.}

By the way, when power is supplied to the hook portion 34 via the wire rope 32, the power transmission efficiency is deteriorated due to the imaginary portion _{of the impedance Z ch.} Therefore, in order to prevent the deterioration of the power transmission efficiency by the capacitor 100, the relationship of the following number 4 using the _{frequency ω, the inductance L w , the capacitance C w} in the wire rope 32, and the capacitance C _{s0 of the capacitor 100 is established.} It should be established. In addition, the equation 4 represents that the inductive reactance in the wire rope 32 is canceled by the capacitive reactance of the capacitor 100.

Since it can be approximated to _{C w} << 1 in the band where the frequency ω is low, the _{capacitance C s0} of the capacitor 100 is calculated based on the following equation 5 using the frequency ω and the inductance L _w.

The controller 4 calculates the electric circuit length L _loop based on the equation 1, the inductance L _w is calculated based on the equation 3, and the capacitance C _s0 of the capacitor 100 is calculated based on the equation 5. After that, the controller 4 switches the energization switch 101 on and off with the _{capacitance C s0 of the capacitor 100 as a target value.} As a result, the controller 4 can keep the reactance component in the power supply system 90 within a certain range, and can suppress the attenuation of the AC power.

For example, a case where capacitors 100 having _{capacitances C s0} of C1, C2, and C3 and capacitance reactances of X _c1 , X _c2 , and X _{c3 are provided will be described.}

As shown in FIG. 8, the inductive reactance in the wire rope 32 increases as shown in the straight line La according to the _{electric circuit length L loop.} The controller 4 selects the capacitor 100 so as to keep the reactance component in the power supply system 90 within a certain range, and energizes the capacitor 100.

Specifically, the controller 4 selects a capacitor 100 having _{an electric circuit length L loop} between L1 and L2 and a capacitance C _{s0 of C1 to energize the controller 4.} As a result, the reactance component in the power supply system 90 is suppressed as shown by the straight line Lb1. Further, the controller 4 selects a capacitor 100 having a _{capacitance C s0 of C2 while the electric circuit length L loop} is between L2 and L3, and energizes the controller 4. As a result, the reactance component in the power supply system 90 is suppressed as shown by the straight line Lb2. Further, the controller 4 selects a capacitor 100 having a _{capacitance C s0 of C3 while the electric circuit length L loop} is between L3 and L4, and energizes the controller 4. As a result, the reactance component in the power supply system 90 is suppressed as shown in the straight line Lb3.

As described above, the crane 1 is provided with a capacitor 100 in at least one of the power transmission circuit 92 and the power reception circuit 96 to reduce the reactance component in the power supply system 90, or the power transmission circuit 92 and the power reception circuit 96. A capacitor 100 is provided in at least one of the correction circuits 104 and 105 in which the induced current flows adjacent to the power transmitting unit 93 or the power receiving unit 95 to reduce the reactance component in the power supply system 90. According to the crane 1, it is possible to prevent deterioration of the power transmission efficiency when supplying electric power to the hook portion 34 via the wire rope 32.

Further, according to the present crane 1, the length of the wire rope 32 (electric circuit length L _loop ) in the power supply system 90 is calculated, and the wire rope 32 increases according to the length of the wire rope 32 (electric circuit length L _{loop). The capacitance C s0} of the capacitor 100 is changed so as to cancel the inductive reactance in. According to the crane 1, even if the length of the wire rope 32 is changed due to the winding or unwinding of the wire rope 32, the transmission efficiency when supplying power to the hook portion 34 via the wire rope 32 is deteriorated. Can be prevented.

Further, according to the present crane 1, a plurality of capacitors 100 are provided, and one or a plurality of capacitors 100 are selected to be energized to change the _{capacitance C s0 of the capacitor 100.} According to such a crane 1, the capacitance C _s0 of the capacitor 100 can be finely and widely changed by the combination of the capacitors 100. Therefore, even if the length of the wire rope 32 changes due to the winding or unwinding of the wire rope 32, it is possible to prevent deterioration of the power transmission efficiency when supplying electric power to the hook portion 34 via the wire rope 32. _{In addition, the capacitance C s0} of the capacitor 100 can be changed without using a variable capacitor such as a variable capacitor. Therefore, since the movable member of the variable capacitor is not required, it is possible to prevent the capacitor 100 from becoming large.

When the electric circuit 94 includes the winch 35 bridged to the boom 31 to form a closed circuit, the electric circuit length L _loop is not the number 1 but the following number 6 using the wire length x and the boom length L. Calculated based on.

Finally, when transmitting a control signal to the electric device 97 (see FIG. 4), DC power is supplied by the power transmission circuit 92, and the control signal is modulated and superimposed on the AC power to superimpose the control signal on the tip of the boom 31. It is also possible to perform data communication from the unit to the hook unit 34.

Further, when the detection signal is transmitted from the electric device 97 (see FIG. 4), DC power is supplied by the power receiving circuit 96, and the detection signal is modulated and superimposed on the AC power, so that the hook portion 34 to the boom 31 It is also possible to perform data communication to the tip.

By superimposing the signal on the AC power in this way, it is possible to apply it to data communication between the tip portion of the boom 31 and the hook portion 34.

Next, the crane 1 according to another embodiment will be described with reference to FIG. Here, the explanation will be focused on different parts.

The power supply system 90 includes a correction circuit 104 or a correction circuit 105 provided with a capacitor 100. When the power supply system 90 includes the correction circuit 104, the power supply system 90 includes a transformer 98 including a power transmission unit 93. When the power supply system 90 includes the correction circuit 105, the power supply system 90 includes a transformer 99 including a power receiving unit 95.

In the correction circuit 104, an induced current flows through the transformer 98. The correction circuit 104 is provided adjacent to the power transmission unit 93 (see (A) in FIG. 9).

In the correction circuit 105, an induced current flows through the transformer 99. The correction circuit 105 is provided adjacent to the power receiving unit 95 (see (B) in FIG. 9).

The transformer 98 has a core 98a such as ferrite, a primary coil 98b (transmission unit 93) on the power transmission circuit 92 side wound around the core 98a, and a secondary coil 98c on the correction circuit 104 side wound around the core 98a. The turns ratio of the transformer 98 can be set arbitrarily.

The transformer 99 has a core 99a such as ferrite, a primary coil 99b (power receiving unit 95) on the power receiving circuit 96 side wound around the core 99a, and a secondary coil 99c on the correction circuit 105 side wound around the core 99a. The turns ratio of the transformer 99 can be set arbitrarily.

Next, the relationship between the turns ratio of the transformers 98 and 99 and the capacitance of the capacitor 100 will be described.

When the capacitor 100 is provided in the correction circuit 104 and when the capacitor 100 is provided in the correction circuit 105, the relationship between the turns ratio of the transformers 98 and 99 and the capacitance of the capacitor 100 is the same. Therefore, in the following, the case where the capacitor 100 is mainly provided in the correction circuit 104 will be described.

_{When the energization switch 106 is turned on, the capacitive reactance X c} of the capacitor 100 for canceling the inductive reactance in the wire rope 32 is indicated by the number 7 using the frequency ω and the capacitance C _{s0 of the capacitor 100.} Here, the capacitance C _s0 of the capacitor 100 is the capacitance when the capacitor 100 is provided in the power transmission circuit 92.

Since impedance transformation ratio of the transformer 98 is proportional to the square of the turns ratio, the capacitive reactance _{X c} of the capacitor 100, the number of turns _{N 1} of the primary coil 98b, the number of turns _{N 2} of the secondary coil 98c, the frequency omega, electrostatic capacitors 100 the number 8 below holds with capacitance C _S1.

The capacitance _{C S1} of the capacitor 100, by organizing number 8, the frequency omega, the capacitive reactance _{X c,} the number of turns _{N 1} of the primary coil 98b, the number of turns _{N 2} of the secondary coil 98c, the electrostatic capacitance of the capacitor 100 It is indicated by the following equation 9 using _{C s0} and an inductance L _w.

For example, the number of turns N ₂ of the secondary coil 98c by setting larger than the number of turns N ₁ of the primary coil 98b, it is possible to use a capacitor 100 having a small capacity than if the capacitor 100 is provided in the power transmission circuit 92. That is, by setting the turns ratio of the transformer 98, it is possible to provide a capacitor 100 having a smaller capacity or a larger capacity than when the capacitor 100 is provided in the power transmission unit 93.

As described above, when the crane 1 includes a correction circuit 104 provided with a capacitor 100, the crane 1 includes a transformer 98 including a power transmission unit 93, and an induced current flows through the correction circuit 104 via the transformer 98. .. Further, when the correction circuit 105 provided with the capacitor 100 is provided, the transformer 99 including the power receiving unit 95 is provided, and the induced current flows through the correction circuit 105 via the transformer 99. According to such a crane 1, the impedance in the correction circuit 104 is converted by the transformer 98. Further, the impedance in the correction circuit 105 is converted by the transformer 99. Therefore, since the choice of the capacitance C _S1 increases, it becomes easy to provide a capacitor 100 optimal capacitance C _S1.

Specifically, by setting the turns ratio of the transformers 98 and 99, a capacitor 100 having a smaller capacity than when the capacitor 100 is provided in the power transmission unit 93 or the power reception unit 95 can be used. The small-capacity capacitor 100 is lower in cost than the large-capacity capacitor 100, and various capacitances are provided. Therefore, since the choice of the capacitance C _S1 increases, it becomes easy to provide a capacitor 100 optimal capacitance C _S1.

Although the configuration for supplying electric power to the hook portion 34 via the wire rope 32 has been described above, the technical idea of the present application can be applied to the configuration for supplying electric power to the jack portion of the out trigger 23 via the steel wire. Specifically, when the cord reel for detecting the length of the outrigger 23 is made of steel wire (when there is a problem in environmental performance or durability to crawl the electric wire), a capacitor is used to prevent deterioration of power transmission efficiency. Therefore, electric power can be supplied to the jack portion of the out trigger 23 via the steel wire.

1 Crane 2 Traveling body 3 Swing body 32 Wire rope 34 Hook part 90 Power supply system 92 Power transmission circuit 93 Power transmission part 95 Power receiving part 96 Power receiving circuit 98 Transformer 99 Transformer 100 Condenser 104 Correction circuit 105 Correction circuit

Claims (4)

A crane equipped with a power supply system that supplies power to the hook via a wire rope.
The power supply system
A power transmission circuit that converts DC power to AC power,
A power transmission unit that transmits AC power to the wire rope,
A power receiving unit that receives AC power from the wire rope and
It is equipped with a power receiving circuit that converts the received AC power into DC power.
A capacitor is provided in at least one of the power transmission circuit and the power reception circuit to reduce the reactance component in the power supply system, or
A capacitor is provided in at least one of the power transmission circuit, the power reception circuit, and the power transmission unit or a correction circuit in which an induced current flows adjacent to the power reception unit to reduce the reactance component in the power supply system. Characterized crane. Calculate the length of the wire rope in the power supply system
The crane according to claim 1, wherein the capacitance of the capacitor is changed so as to cancel the inductive reactance in the wire rope that increases with the length of the wire rope. With multiple capacitors
The crane according to claim 2, wherein the capacitance of the capacitor is changed by selecting one or a plurality of the capacitors and energizing them. When the correction circuit provided with the capacitor is provided,
A transformer including the power transmission unit or the power reception unit is provided.
The crane according to any one of claims 1 to 3, wherein an induced current flows through the correction circuit through the transformer.

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