Patent Description:
In a crane including a front member such as a boom and jib which are capable of derricking, a backstop which limits a standing operation of the front member is disposed on a rear surface side of the front member, and the backstop prevents the front member from excessively falling rearward. For example, the backstop disclosed in <CIT> internally has a buffer spring, and the standing operation of the boom is limited by an operation of the buffer spring. <CIT> discloses a crane according to the preamble of claims <NUM>, <NUM>, <NUM>, <NUM> and <NUM>, wherein a backstop has a second jib over-winding detection device (<NUM>) and is provided between the back surface of the jib and a swing body.

According to <CIT>, the standing operation of the boom can be performed even in a case where the backstop malfunctions. Accordingly, there is room for improvement in safely driving the crane.

The present invention is made in view of the above-described circumstances, and an object thereof is to provide a crane which can be safely operated in a case where a backstop malfunctions.

According to an embodiment of the present invention, there is provided a crane including a front member capable of derricking and a backstop disposed on a rear surface side of the front member so as to limit a standing operation of the front member. The crane has an angle sensor that detects an angle of the front member, an operation detection unit that detects whether or not the backstop is in contact with a contact portion that is a target, and a controller that controls a derricking operation of the front member. The controller stops the standing operation of the front member in a case where the controller determines that the angle of the front member is equal to or larger than a predetermined angle, based on a detection signal output from the angle sensor, and in a case where the controller determines that the backstop is in contact with the contact portion, based on a detection signal output from the operation detection unit.

The crane according to the embodiment of the present invention can be safely operated when the backstop malfunctions. Objects, configurations, and advantageous effects other than those described above will be clarified by description of the following embodiments.

Hereinafter, each embodiment of a crane according to the present invention will be described with reference to the drawings. Here, for the sake of convenience of description, forward, rearward, rightward, leftward, upward, and downward directions are defined when viewed from an operator who gets on an operation seat. In addition, in the following description, in a case where the description needs to distinguish a right side and a left side from each other with regard to the same configuration, "L" meaning the left side and "R" meaning the right side will be respectively given to reference numerals corresponding to the configurations so as to distinguish both of these from each other. In the respective embodiments, the same reference numerals will be given to the same configurations, and repeated description will be omitted.

In the following disclosure, the first and second embodiments refer to the crane of claims <NUM> to <NUM>, the third embodiment refers to crane of claim <NUM>, forth embodiment refers to crane of claim <NUM> and the fifth embodiment refers to the crane of claim <NUM>.

<FIG> is a side view illustrating an external configuration of a tower crane 100A according to a first embodiment of the present invention. The tower crane 100A (hereinafter, abbreviated as the crane 100A) includes a lower traveling body <NUM>, an upper turning body <NUM> pivotally disposed on the lower traveling body <NUM> via a turning wheel, a tower boom <NUM> (hereinafter, abbreviated as the tower <NUM>) serving as a front member whose proximal end portion is pivotally supported by the upper turning body <NUM>, and a jib boom <NUM> (hereinafter, abbreviated as the jib <NUM>) serving as a front member pivotally supported by a distal end portion of the tower <NUM>. A front part of the upper turning body <NUM> has an operation room <NUM>, and a counterweight <NUM> is attached to a rear part of the upper turning body <NUM>. The operation room <NUM> has an operation lever (not illustrated) for performing various operations and a display device <NUM> (refer to <FIG>).

The upper turning body <NUM> is equipped with a hook winding drum <NUM> serving as a winch drum for hook winding, a tower derricking drum <NUM> serving as a winch drum for tower derricking, and a jib derricking drum <NUM> serving as a winch drum for jib derricking. The hook winding drum <NUM>, the tower derricking drum <NUM>, and the jib derricking drum <NUM> are respectively driven by hydraulic motors (not illustrated). In addition, in an emergency, a controller 200A transmits a stop signal so as to stop the respective drums <NUM>, <NUM>, and <NUM> by respectively operating a hook winding stop electromagnetic valve 105a, a tower derricking stop electromagnetic valve 106a, and a jib derricking stop electromagnetic valve 102a (refer to <FIG>).

A winding rope <NUM> is wound around the hook winding drum <NUM>, and the winding rope <NUM> is connected to a hook <NUM> via a top portion of the tower <NUM> and a distal end portion of the jib <NUM>. If the hook winding drum <NUM> is driven, the winding rope <NUM> is wound or unwound, thereby causing the hook <NUM> to ascend and descend.

One end of a tower pendant rope <NUM> is connected to a distal end of the tower <NUM>, and the other end of the tower pendant rope <NUM> is connected to a tower upper spreader <NUM>. A tower derricking rope <NUM> is wound around the tower derricking drum <NUM> by being wrapped multiple times between the tower upper spreader <NUM> and a tower lower spreader <NUM> via a top portion of a mast <NUM>. If the tower derricking drum <NUM> is driven, the tower derricking rope <NUM> is wound or unwound, thereby changing an interval between the tower lower spreader <NUM> and the tower upper spreader <NUM>. Accordingly, the tower <NUM> performs a derricking operation.

A tower strut <NUM> is pivotally supported by a distal end portion of the tower <NUM>. The tower strut <NUM> is formed in a triangular shape by using a front strut 140a, a rear strut 140b, and a connection rod 140c which connects the front strut 140a and the rear strut 140b to each other.

One apex corner portion of the tower strut <NUM>, that is, a distal end portion of the front strut 140a is connected to a distal end portion of the jib <NUM> by using a jib pendant rope <NUM>. The other apex corner portion of the tower strut <NUM>, that is, a distal end portion of the rear strut 140b is connected to a jib derricking rope <NUM> via a tower strut pendant rope <NUM> and a jib upper spreader <NUM>. The jib derricking rope <NUM> is wound around the jib derricking drum <NUM> by being wrapped multiple times between the jib upper spreader <NUM> and a jib lower spreader <NUM>. If the jib derricking drum <NUM> is driven, the jib derricking rope <NUM> is wound or unwound, thereby causing the tower strut <NUM> to pivot in a forward-rearward direction. Accordingly, the jib <NUM> performs the derricking operation. A pivot angle of the jib <NUM> is detected by a jib angle sensor (angle sensor) <NUM>, and a detection signal is output from the jib angle sensor <NUM> to the controller 200A (refer to <FIG>).

A pair of right and left tower backstops <NUM> (<NUM> and 50R) is disposed between a main frame 103a of the upper turning body <NUM> and the tower <NUM>. <FIG> is a side view of the tower backstop <NUM>.

The tower backstop <NUM> limits a pivot range of the tower <NUM> so that the tower <NUM> does not pivot at a maximum angle or more. The tower backstop <NUM> has an outer cylinder <NUM>, an inner cylinder <NUM>, and a compression spring <NUM>. One end of the outer cylinder <NUM> has an attachment member <NUM> which is pivotably attached to the tower <NUM>. The attachment member <NUM> is pivotally supported by a pin 54a in a supporting portion (not illustrated) disposed in the tower <NUM>. The inner cylinder <NUM> is slidably attached to an inner side of the outer cylinder <NUM>. One end of the inner cylinder <NUM> has a holding member <NUM> which is pivotably attached to the main frame 103a. The holding member <NUM> is pivotally supported by a pin 55a in the main frame 103a. The compression spring <NUM> is inserted into an outer periphery of the inner cylinder <NUM>, and is disposed between the other end portion 51b of the outer cylinder <NUM> and the holding member <NUM>. The compression spring <NUM> biases the outer cylinder <NUM> to the tower <NUM> side (upward in <FIG>). Although not illustrated in <FIG>, the main frame 103a has a tower backstop limit switch <NUM> (hereinafter, abbreviated as a limit switch <NUM>) operated in conjunction with a displacement of the outer cylinder <NUM>.

The tower <NUM> performs a standing operation, and the outer cylinder <NUM> moves downward while the compression spring <NUM> is compressed. If the tower <NUM> stands up at a predetermined angle, a signal is output to the controller 200A via the limit switch <NUM>. The tower derricking stop electromagnetic valve 106a is operated, thereby stopping the tower derricking drum <NUM> (refer to <FIG>). Therefore, the tower <NUM> is held at a maximum standing angle. Normally, the maximum standing angle of the tower <NUM> is approximately <NUM> degrees.

A rear surface side of the jib (front member) <NUM> has a pair of right and left jib backstops (backstop) <NUM>. <FIG> is an enlarged view of a part A in <FIG>, and is a side view of a jib backstop <NUM>. <FIG> is a side view of the jib backstop <NUM> illustrating a state where the other end 70b of the jib backstop <NUM> is in contact with a target <NUM>. <FIG> is a side view of the jib backstop <NUM> illustrating a state where the jib <NUM> stands up to the maximum standing angle.

The jib backstop <NUM> limits a pivot range of the jib <NUM> so that the jib <NUM> does not pivot at a maximum angle or more. One end 70a of the jib backstop <NUM> is pivotably attached to a support portion <NUM> of the jib <NUM>. The other end 70b of the jib backstop <NUM> is a free end. A connection member <NUM> for connecting the jib backstop <NUM> and the jib <NUM> to each other is disposed at a position on the other end 70b side from the center of the jib backstop <NUM>.

If the jib <NUM> pivots upward (rearward) around a connection pin <NUM> from a horizontal position and stands up at a predetermined angle (for example, <NUM>°), the other end 70b of the jib backstop <NUM> is brought into contact with the target (contact portion) <NUM> as illustrated in <FIG>. If the jib <NUM> further pivots rearward around the connection pin <NUM>, the jib backstop <NUM> allows the jib <NUM> to pivot rearward while being displaced so that the jib backstop <NUM> itself shrinks. Then, as illustrated in <FIG>, if the jib <NUM> finally stands up to the maximum standing angle (for example, <NUM>°), the pivoting of the jib <NUM> is limited the jib <NUM> so that the jib <NUM> does not pivot further rearward (counterclockwise direction). In this way, the jib backstop <NUM> performs a stretching operation in an axial direction in accordance with the standing operation of the jib <NUM>.

A structure of the jib backstop <NUM> will be described with reference to <FIG>, <FIG> in addition to <FIG>. <FIG> is an enlarged plan view of a main part of the jib backstop <NUM> when the jib <NUM> is in a state illustrated <FIG>. <FIG> is an enlarged side view of a main part of the jib backstop <NUM> when the jib <NUM> is in the state illustrated <FIG>. <FIG> is an enlarged plan view of a main part of the jib backstop <NUM> when the jib <NUM> is in a state illustrated in <FIG>. <FIG> an enlarged side view of a main part of the jib backstop <NUM> when the jib <NUM> is in the state illustrated in <FIG>.

As illustrated in <FIG>, <FIG>, the jib backstop <NUM> has an outer cylinder <NUM>, an inner cylinder <NUM> slidably disposed inside the outer cylinder <NUM>, and a compression spring <NUM>. The distal end portion of the outer cylinder <NUM> configures the other end 70b of the jib backstop <NUM>, and comes into contact with the target <NUM>. A flange <NUM> having a rectangular shape is disposed in a proximal end portion of the outer cylinder <NUM>. A connection plate <NUM> of a jib backstop operation detection device <NUM> (to be described later) is attached to the flange <NUM>. Thee proximal end portion of the inner cylinder <NUM> has a holding member <NUM>, and the holding member <NUM> has a pair of attachment members <NUM>. A support portion <NUM> of the jib <NUM> is interposed between the pair of attachment members <NUM>, and a pin <NUM> is inserted so that the inner cylinder <NUM> is pivotally supported by the support portion <NUM>.

The compression spring <NUM> is inserted into an outer periphery of the inner cylinder <NUM>, and is interposed between the connection plate <NUM> and the holding member <NUM>. A biasing force of the compression spring <NUM> acts in a pressing direction of the connection plate <NUM>. In this manner, the outer cylinder <NUM> is pressed against and held by a distal end side (left side in <FIG>). If the jib <NUM> pivots rearward in a state where the distal end portion of the outer cylinder <NUM> is in contact with the target <NUM>, the outer cylinder <NUM> is moved to the proximal end side (right side in <FIG>) of the inner cylinder <NUM> against the biasing force of the compression spring <NUM>. That is, the jib backstop <NUM> shrinks. In this way, the outer cylinder <NUM> is displaced as the jib <NUM> pivots, thereby causing jib backstop <NUM> to perform the stretching operation.

The jib backstop operation detection device (operation detection unit) <NUM> which detects an operation of the jib backstop <NUM> is disposed on a side of one end 70a of the jib backstop <NUM>. The jib backstop operation detection device <NUM> will be described in detail with reference to <FIG> and <FIG> in addition to <FIG>, <FIG>. <FIG> is a side view of the jib backstop <NUM> illustrating a part B in <FIG> in detail, and <FIG> is a view of the jib backstop <NUM> illustrated in <FIG>, which is taken along an arrow C.

As illustrated in <FIG> and <FIG>, the jib backstop operation detecting device (operation detection unit) <NUM> which detects the operation of the jib backstop <NUM> is disposed on the side of one end 70a of the jib backstop <NUM>. As illustrated in <FIG>, the jib backstop operation detection device <NUM> mainly includes the connection plate <NUM> connected to the flange <NUM> of the outer cylinder <NUM>, a base plate <NUM> to which a jib backstop limit switch (first limit switch) <NUM> and a jib excessive winding limit switch <NUM> (second limit switch) <NUM> are attached, and an elongated slide bar (moving member) <NUM> laid between the connection plate <NUM> and the base plate <NUM>.

The connection plate <NUM> has substantially the same outer shape as that of the flange <NUM>, and is fixed to the flange <NUM> by using a bolt. An L-shaped bracket <NUM> is attached to an upper portion of the connection plate <NUM>, and a columnar fixing portion <NUM> is attached to the bracket <NUM>. A screw hole is disposed on an upper surface of the fixing portion <NUM>, and one end of the slide bar <NUM> is fixed thereto by using a bolt <NUM>. In this manner, the slide bar <NUM> slides in conjunction with the movement of the outer cylinder <NUM> in the axial direction (forward-rearward direction of the jib <NUM>, rightward-leftward direction in <FIG>).

The base plate <NUM> is fixed to a base fixing portion (not illustrated) attached to the holding member <NUM> of the inner cylinder <NUM>, and is held in a horizontal state. The base plate <NUM> has a guide <NUM> for slidably supporting the other end of the slide bar <NUM>. The guide <NUM> guides the movement of the slide bar <NUM> in a longitudinal direction (axial direction of the jib backstop <NUM>). A pair of right and left round bars <NUM> is disposed so as to penetrate the flange <NUM>, the connection plate <NUM>, and the holding member <NUM>, and each of the round bars <NUM> is fixed by using a nut <NUM>. A crank-shaped intermediate support <NUM> is fixed to a substantially center position of the round bars <NUM>. A penetrating hole through which the slide bar <NUM> penetrates is disposed in an upper portion of the intermediate support <NUM>, and the slide bar <NUM> is slidably supported by the intermediate support <NUM>.

A striker <NUM> is disposed in the other end of the slide bar <NUM>. If the slidebar <NUM> slides, in accordance with a slide position, the striker <NUM> presses down a roller <NUM> of a jib backstop limit switch <NUM> (hereinafter, abbreviated as a limit switch <NUM>) and/or a roller <NUM> of a jib excessive winding limit switch <NUM> (hereinafter, abbreviated as a limit switch <NUM>) rollers <NUM>, thereby turning on a contact. If the respective limit switches <NUM> and <NUM> are operated, an ON-signal (operation signal) is output to the controller 200A. In the present embodiment, the limit switches <NUM> and <NUM> are roller lever type. However, the other types of the limit switch, for example, a V-lever type may be used.

As illustrated in <FIG>, a jib backstop operation detection device <NUM> on the left side and a jib backstop operation detection device 80R on the right side are arranged in parallel with each other in the rightward-leftward direction of the jib <NUM>, and are arranged at the same position in the forward-rearward direction of the jib <NUM>. A limit switch <NUM> and a limit switch 91R are arranged at the same position S1 in the forward-rearward direction of the jib <NUM>. Therefore, the limit switches <NUM> and 91R are operated at the same timing. On the other hand, a limit switch <NUM> is located at a position S3 forward of the limit switch <NUM> as much as a distance L3 (corresponding to a displacement difference L3 in <FIG>), and a limit switch 93R is located at a position S2 forward of the limit switch 91R as much as a distance L4 (corresponding to a displacement amount L4 in <FIG>) (L3>L4). That is, the limit switch <NUM> is located slightly forward of the limit switch 93R. Therefore, the limit switch 93R is operated earlier than the limit switch <NUM>. As a matter of course, a positional relationship between the limit switch <NUM> and the limit switch 93R may be reversed.

A relationship between a position of the limit switches <NUM> and <NUM> and a pivot position of the jib <NUM> will be described in detail with reference to <FIG> is a schematic view illustrating a positional relationship between the pivot position of the jib <NUM> and the limit switches <NUM> and <NUM>. <FIG> is a schematic view illustrating a positional relationship between a slide position of the slide bar <NUM> and the limit switches <NUM> and <NUM>. As illustrated in <FIG>, if the jib <NUM> starts the standing operation from a horizontal position and the jib <NUM> pivots to a position P1' , the jib backstop <NUM> starts to come into contact with the target <NUM>. That is, the position P' is a "contact position" where the jib <NUM> or the backstop <NUM> starts to come into contact with the target <NUM>. In this case, as illustrated in <FIG>, in conjunction with the standing operation of the jib <NUM>, the slide bar <NUM> also slides in a forward direction, and is displaced to a position S' corresponding to the position P'.

If the jib <NUM> pivots from the position P1' to the position P1 where the jib <NUM> pivots in a counterclockwise direction (rearward) around the connection pin <NUM> as much as a first pivot angle (<NUM>° to <NUM>°), the jib backstop <NUM> shrinks as much as a displacement amount L1 (first displacement amount) corresponding to a first pivot angle. Accordingly, the slide bar <NUM> is displaced to a position S1 (first position) corresponding to the position P1. If the slide bar <NUM> moves to the position S1, the striker <NUM> presses down the roller <NUM> of the limit switch <NUM>, thereby turning on the limit switch <NUM> (states illustrated in <FIG>). The limit switches <NUM> and 91R are disposed at the same position S1. Accordingly, the limit switches <NUM> and 91R are turned on at the same time.

Here, in the present embodiment, a reason that the first pivot angle is set in a range of <NUM>° to <NUM>° is as follows. Due to variations in manufacturing the jib backstops <NUM> and 70R or an error of an attachment position of the limit switches <NUM> and 91R, there is a possibility that of variations in a position (contact position) where the jib backstops <NUM> and 70R respectively start to come into contact with targets <NUM> and 135R. That is, according to the present embodiment, in order to reliably detect that the jib backstop <NUM> is in contact with the target <NUM>, the limit switch <NUM> is operated at the position P1 where the jib <NUM> stands up at approximately <NUM>° to <NUM>° from the position P1' where the jib backstop <NUM> starts to come into contact with the target <NUM>. In this manner, in a case where the limit switch <NUM> is operated, it can be determined that the jib backstop <NUM> is reliably in contact with the target <NUM>.

In a state where the jib backstop 70R is in contact with the target 135R, if the jib <NUM> pivots from the position P1 to the position P2, the jib backstop 70R shrinks as much as a displacement amount L4, and the slide bar 88R moves to a position S2 corresponding to the position P2. If the slide bar 88R moves to the position S2, the striker 89R presses down the roller 94R of the limit switch 93R, thereby turning on the limit switch 93R. In this case, the limit switch <NUM> is disposed at a position S3. Accordingly, the limit switch <NUM> is not operated. Although details will be described later, if the limit switch 93R is operated, the standing operation of the jib <NUM> is stopped. The winding operation of the hook <NUM> is not stopped in a state where the jib <NUM> is located the position P2.

If the jib <NUM> reaches a position P3 where the jib <NUM> pivots (stands up) as much as a second pivot angle (<NUM>° to <NUM>°) in the counterclockwise direction around the connection pin <NUM> from the position P1, the jib backstop <NUM> shrinks as much as a displacement amount L2 (second displacement amount) corresponding to a second pivot angle. Accordingly, the slide bar <NUM> moves to a position S3 (second position) corresponding to the position P3. If the slide bar <NUM> moves to the position S3, the striker <NUM> presses down the roller <NUM> of the limit switch <NUM>, thereby turning on the limit switch <NUM> (states in <FIG>). If the limit switch <NUM> is operated, in addition to the stop of the standing operation of the jib <NUM>, the winding operation of the hook <NUM> is also stopped.

Next, a configuration of the controller 200A mounted on the crane 100A will be described. <FIG> is a block diagram illustrating an input to and an output from to the controller 200A. The controller 200A is a control device for controlling each part of the crane 100A. Although not illustrated, the controller 200A includes a CPU for performing various calculations, a memory serving as a storage device, a communication interface, and other peripheral devices.

Each detection signal is input to the controller 200A from the jib angle sensor <NUM> for detecting an angle of the jib <NUM>, the limit switch <NUM> for detecting an operation of the tower backstop <NUM>, the limit switches <NUM>, 91R, <NUM>, and 93Rfor detecting an operation of the jib backstop <NUM>, and other sensors (not illustrated). The controller 200A performs a predetermined computation process, based on each input detection signal, and outputs a control signal to the hook winding stop electromagnetic valve 105a, the tower derricking stop electromagnetic valve 106a, the jib derricking stop electromagnetic valve 102a, the display device <NUM>, and other devices (not illustrated).

Next, controlling of the derricking operation of the jib <NUM> controlled by the controller 200A will be described. <FIG> is a flowchart illustrating a control procedure of the derricking operation of the jib <NUM> controlled by the controller 200A. As illustrated in <FIG>, if the derricking operation of the jib <NUM> starts, the controller 200A acquires operation information of the jib backstop <NUM>, based on an operation signal output from the limit switch <NUM> (Step S1). Based on a detection signal output from the jib angle sensor <NUM>, the controller 200A acquires angle data of the jib <NUM> (Step S2). Next, the controller 200A determines whether or not a relationship between the operation of the jib backstop <NUM> and an angle of the jib <NUM> is normal (Step S3). An operation determination table 205A for determining whether or not the operation of the jib backstop <NUM> is normal is stored in a memory of the controller 200A.

<FIG> is a view illustrating the operation determination table 205A which stipulates whether or not the operation of the jib backstop <NUM> is normal. The operation determination table 205A illustrated in <FIG> stipulates whether or not the operation of the jib backstop <NUM> is normal, based on an angle (jib angle) θ and the limit switches <NUM> and 91R. Specifically, in a case where the angle (the jib angle) θ of the jib <NUM> is smaller than <NUM>°, and in a case where both the limit switches <NUM> and 91R are turned off, it is stipulated that the operation of the jib backstop <NUM> is "normal". In a case where the jib angle θ is <NUM> degrees or larger, it is stipulated that the operation of the jib backstop <NUM> is defined as "normal" only in a case where both the limit switches <NUM> and 91R are turned on. In a case where at least one of the limit switches <NUM> and 91R are turned off, it is stipulated that the operation of the jib backstop <NUM> is "abnormal".

Here, the jib angle θ=<NUM>° means a state where the jib <NUM> is located at the position P1 (refer to <FIG>). If the operation is normal, the other end 70b of the jib backstop <NUM> is reliably in contact with the target <NUM>, and both the limit switches <NUM> and 91R are supposed to output the ON-signal. Therefore, according to the present embodiment, in a case where the jib angle θ is <NUM>° or larger, and in a case where at least one of the limit switches <NUM> and 91R is turned off, it is determined that the jib backstop <NUM> is not in contact with the target <NUM> due to a failure (the slide bar <NUM> is not moved to the position S1), and it is stipulated that the operation of the jib backstop <NUM> is abnormal.

In a case where the controller 200A determines that the operation in Step S3 is normal (S3 / Yes), the controller 200A performs the derricking operation of the jib <NUM> (Step S4). In a case where the jib <NUM> performs the standing operation up to the position P2 and the limit switch 93R is operated (Step S5 / Yes), the controller 200A operates the jib derricking stop electromagnetic valve 102a (refer to <FIG>), and stops the derricking operation of the jib <NUM> (Step S6). In a case where the controller 200A determines that the operation in Step S3 is abnormal (S3 / No), the controller 200A proceeds to Step S6, and stops the derricking operation of the jib <NUM>. In this manner, the jib <NUM> is prevented from performing the standing operation in a state where the jib backstop <NUM> is not in contact with the target <NUM>. In a case where it is determined that the operation in Step S3 is abnormal, the controller 200A outputs an abnormality signal to the display device <NUM>, and notifies the display device <NUM> of a fact that the jib backstop <NUM> is not in contact with the target <NUM>.

In a case where the jib <NUM> performs the derricking operation up to the position P3 and the limit switch <NUM> is turned on (S7 / Yes), the controller 200A operates the hook winding stop electromagnetic valve 105a (refer to <FIG>), and stops the winding operation of the hook <NUM> (Step S8) so as to complete the process.

As described above, according to the first embodiment, the controller 200A determines that the angle θ of the jib <NUM> is <NUM>°or larger. In a case where it is determined that the other end 70b of the backstop <NUM> is not in contact with the target <NUM>, based on a detection signal of the limit switches <NUM> and 91R, the controller 200A is configured to stop the standing operation of the jib <NUM>. Accordingly, when the jib backstop <NUM> malfunctions, the crane 100A can be safely operated. The malfunction of the jib backstop <NUM> can be detected by the limit switch <NUM> which is turned on or off. Therefore, the jib backstop operation detection device <NUM> can adopt an inexpensive and simple configuration.

Here, in some cases, the limit switch <NUM> is disposed in the crane in the related art in order to prevent the jib from being excessively wound. In this case, the limit switch <NUM> is located at a position between the position S1 and the position S3. If the design is changed so that the limit switch <NUM> is turned on when the jib <NUM> pivots to a position between the position P1 and the position P3, whether or not the jib backstop <NUM> is in contact with the target <NUM> can be detected without increasing the number the limit switches. However, if the limit switch <NUM> is moved to the position between the position S1 and the position S3, the jib <NUM> stops the standing operation at the position between the position P1 and the position P3. Accordingly, a pivot range of the jib <NUM> is narrowed compared to that in the related art. Therefore, this configuration is not preferable since original lifting work of the crane is adversely affected.

On the other hand, according to the first embodiment, the limit switch <NUM> is additionally located at the position S1 in order to detect the malfunction of the jib backstop <NUM>. In this manner, an exceptional operation effect is achieved in that safety can be improved without impairing workability of the crane 100A. Even if the jib angle θ is <NUM>° or larger, in a case where at least one of the limit switches <NUM> and 91R is turned off, it is determined that the jib backstop <NUM> is not in contact with the target <NUM> (abnormal), and the standing operation of the jib <NUM> is stopped. Therefore, the crane 100A can be more safely operated.

In a crane 100B according to a second embodiment, a configuration of a jib backstop operation detection device is partially different from that according to the first embodiment. Hereinafter, points different from those according to the first embodiment will be mainly described. <FIG> is a plan view illustrating a configuration of a jib backstop operation detection device <NUM> according to the second embodiment, and <FIG> is a side view illustrating the configuration of the jib backstop operation detection device <NUM> according to the second embodiment.

As illustrated in <FIG>, according to the second embodiment, moving members for operating the limit switch <NUM> and the limit switch <NUM> are configured to be respectively separate members. Specifically, whereas a slide bar <NUM> serving as a second moving member operates only the limit switch <NUM>, a side bar <NUM> serving as first moving member operates only the limit switch <NUM>. According to the first embodiment, the slide bar <NUM> and the side bar <NUM> are integrated with each other so as to configure one moving member.

The side bar <NUM> is formed of an elongated plate-shaped body. One end thereof is fixed to a bracket <NUM> attached to a side portion of the connection plate <NUM> by using a bolt <NUM> and the other end is slidably supported by a guide pin <NUM>. The guide pin <NUM> engages with an elongated hole <NUM> disposed in the side bar <NUM>, and guides the sidebar <NUM> to move in the forward-rearward direction. The guide pin <NUM> is fixed to a side bracket <NUM> fixed to the base plate <NUM>.

According to this configuration, the other end 70b of the jib backstop <NUM> comes into contact with the target <NUM>. In conjunction with the movement of the outer cylinder <NUM> in the forward-rearward direction, the side bar <NUM> is also moved in the forward-rearward direction. Then, if the jib <NUM> pivots to the position P1 (refer to <FIG>), a striker <NUM> disposed in the other end of the side bar <NUM> pressed down the roller <NUM> of the limit switch <NUM>, thereby turning on the contact of the limit switch <NUM>.

In this way, the second embodiment can also achieve the same operation effect as that according to the first embodiment. In particular, according to the second embodiment, the side bar <NUM> and the limit switch <NUM> can be externally attached to the existing crane. Therefore, there is an advantage in that the existing crane can be safely operated through simple remodeling.

A configuration of a crane 100C according to a third embodiment is different from the configuration according to the first and second embodiments in that a wire-type displacement meter <NUM> is used instead of the limit switch <NUM> in order to detect the operation of the jib backstop <NUM>. That is, a jib backstop operation detection device <NUM> according to the third embodiment includes the wire-type displacement meter <NUM>. Hereinafter, points different from those according to the first and second embodiments will be mainly described. <FIG> is a plan view illustrating a configuration of the jib backstop operation detection device <NUM> according to the third embodiment, and <FIG> is a side view illustrating the configuration of the jib backstop operation detection device <NUM> according to the third embodiment.

As illustrated in <FIG>, the wire-type displacement meter <NUM> (hereinafter, abbreviated as the displacement meter <NUM>) for detecting a displacement amount generated by the stretching operation of the jib backstop <NUM> is disposed in the base plate <NUM>. A distal end portion of a wire <NUM> of the displacement meter <NUM> is fixed to a fixing portion <NUM>. If the outer cylinder <NUM> moves in the forward-rearward direction, the wire <NUM> is pulled out or wound up. The displacement amount of the wire <NUM> is detected by a potentiometer incorporated in the displacement meter <NUM>. In this manner, the operation of the jib backstop <NUM> can be detected. A detection signal of the displacement meter <NUM> is input to a controller 200C. Based on the detection signal of the displacement meter <NUM> and the detection signal of the jib angle sensor <NUM>, the controller 200C performs permission control of the derricking operation of the jib <NUM>.

<FIG> is a block diagram illustrating an input to and an output from the controller 200C. The controller 200C according to the third embodiment is a control device for controlling each part of the crane 100C. Although not illustrated, the controller 200C includes a CPU for performing various calculations, a memory serving as a storage device, a communication interface, and other peripheral devices.

As illustrated in <FIG>, each detection signal is input to the controller 200C from the jib angle sensor <NUM> for detecting an angle of the jib <NUM>, the limit switch <NUM> for detecting an operation of the tower backstop <NUM>, the displacement meter <NUM> for detecting an operation of the jib backstop <NUM>, and other sensors (not illustrated). The output side of the controller 200C is the same as that according to the first embodiment.

<FIG> is a flowchart illustrating a control procedure of the derricking operation of the jib <NUM> according to the third embodiment. As illustrated in <FIG>, the controller 200C acquires displacement data of the jib backstop <NUM> from the displacement meter <NUM> (Step S1-<NUM>), and acquires angle data of the jib <NUM>, based on the detection signal from the jib angle sensor <NUM> (Step S2). Next, the controller 200C determines whether or not a displacement amount D of the jib backstop <NUM> is a threshold D1 or greater (Step S3-<NUM>). In a case where the displacement amount D is the threshold D1 or greater (Step S3-<NUM> / Yes), the controller 200C performs the derricking operation of the jib <NUM> (Step S4). Here, the threshold D1 is used in order to determine whether or not the other end 70b of the jib backstop <NUM> is reliably in contact with the target <NUM>. For example, the threshold D1 is set in advance to a displacement amount L1 (refer to <FIG>).

Next, if the controller 200C determines that the displacement amount D is a threshold D2 or greater (Step S5-<NUM> / Yes), the controller 200C operates the jib derricking stop electromagnetic valve 102a, and stops the derricking operation of the jib <NUM> (Step S6). Here, for example, the threshold D2 is set in advance to a displacement amount L1+L4 (refer to <FIG>).

In a case where the controller 200C determines that the displacement amount D is smaller than the threshold D1 (S3-<NUM> / No) in the determination process in Step S3-<NUM>, the controller 200C proceeds to Step S6 so as to stop the derricking operation of the jib <NUM>, and notifies the display device <NUM> of a fact that the operation is abnormal. In this manner, the jib <NUM> is prevented from performing the standing operation in a state where the jib backstop <NUM> is not in contact with the target <NUM>.

In a case where the controller 200C determines that the displacement amount D is a threshold D3 or greater (S7-<NUM> / Yes), the controller 200C operates the hook winding stop electromagnetic valve 105a so as to stop the winding operation of the hook <NUM> (Step S8), and completes the process. Here, for example, the threshold D3 is set in advance to a displacement amount L2 (refer to <FIG>).

In this way, similarly to the first and second embodiments, according to the third embodiment, even if the jib backstop <NUM> malfunctions, the crane 100C can also be safely operated. Moreover, the displacement meter <NUM> is used instead of the limit switches <NUM> and <NUM>. Accordingly, the configuration of the jib backstop operation detection device <NUM> can be simplified, and can be inexpensively manufactured.

A configuration of a crane 100D according to a fourth embodiment is different from the configuration of the third embodiment in that a pin-type load cell (load sensor) <NUM> is used instead of the wire-type displacement meter <NUM> in order to detect the operation of the jib backstop <NUM>. That is, the jib backstop operation detection device <NUM> according to the fourth embodiment is configured to include the pin-type load cell <NUM>. Hereinafter, points different from those according to the third embodiment will be mainly described. <FIG> is a side view illustrating the configuration of the jib backstop operation detection device <NUM> according to the fourth.

As illustrated in <FIG>, the pin-type load cell <NUM> (load sensor / hereinafter, abbreviated as the load cell <NUM>) for detecting a load acting on the pin <NUM> is incorporated in the pin <NUM>. The load cell <NUM> detects a change in the load acting on the pin <NUM> as the other end 70b of the jib backstop <NUM> comes into contact with the target <NUM>. According to the fourth embodiment, based on the change in the load, it is determined whether the jib backstop <NUM> is in contact with the target <NUM> or whether the jib <NUM> pivots at a maximum standing angle (upper limit angle).

The configuration will be described in detail with reference to <FIG> and <FIG>. <FIG> is a block diagram illustrating an input to and an output from a controller 200D. The controller 200D according to the fourth embodiment is a control device for controlling each part of the crane 100D. Although not illustrated, the controller 200D includes a CPU for performing various calculations, a memory serving as a storage device, a communication interface, and other peripheral devices.

As illustrated in <FIG>, each detection signal is input to the controller 200D from the jib angle sensor <NUM> for detecting an angle of the jib <NUM>, the limit switch <NUM> for detecting an operation of the tower backstop <NUM>, the load cell <NUM> for detecting an operation of the jib backstop <NUM>, and other sensors (not illustrated). The output side of the controller 200D is the same as that according to the third embodiment.

<FIG> is a flowchart illustrating a control procedure of the derricking operation of the jib <NUM> according to the fourth embodiment. As illustrated in <FIG>, the controller 200D acquires load data of the jib backstop <NUM> from the load cell <NUM> (Step S1-<NUM>), and acquires angle data of the jib <NUM>, based on the detection signal from the jib angle sensor <NUM> (Step S2). Next, the controller 200D determines whether or not a load W of the jib backstop <NUM> is a threshold Wl or greater (Step S3-<NUM>). In a case where the load W is the threshold Wl or greater (Step S3-<NUM> / Yes), the controller 200D performs the derricking operation of the jib <NUM> (Step S4). Here, the threshold Wl is used in order to determine whether or not the other end 70b of the jib backstop <NUM> is reliably in contact with the target <NUM>. For example, the threshold Wl is set in advance to a load value acting on the pin <NUM> in a case where the jib backstop <NUM> shrinks as much as a displacement amount L1 (refer to <FIG>).

Next, if the controller 200D determines that the load W is a threshold W2 or greater (Step S5-<NUM> / Yes), the controller 200D operates the jib derricking stop electromagnetic valve 102a so as to stop the derricking operation of the jib <NUM> (Step S6). Here, for example, the threshold W2 is set in advance to a load value acting on the pin <NUM> in a case where the jib backstop <NUM> shrinks as much as a displacement amount L1+L4 (refer to <FIG>).

In a case where the controller 200D determines that the load W is smaller than the threshold Wl (S3-<NUM> / No) in the determination process in Step S3-<NUM>, the controller 200D proceeds to Step S6 so as to stop the derricking operation of the jib <NUM>, and notifies the display device <NUM> of a fact that the operation is abnormal. In this manner, the jib <NUM> is prevented from performing the standing operation in a state where the jib backstop <NUM> is not in contact with the target <NUM>.

In a case where the controller 200D determines that the load W is a threshold W3 or greater (S7-<NUM> / Yes), the controller 200D operates the hook winding stop electromagnetic valve 105a so as to stop the winding operation of the hook <NUM> (Step S8), and completes the process. Here, for example, the threshold W3 is set in advance to a load value acting on the pin <NUM> in a case where the jib backstop <NUM> shrinks as much as a displacement amount L2 (refer to <FIG>).

In this way, similarly to the third embodiment, according to the fourth embodiment, the crane 100D can also be safely operated even if the jib <NUM> or the backstop <NUM> malfunctions. Moreover, the load cell <NUM> is used instead of the displacement meter <NUM>. Therefore, the configuration of the jib backstop operation detection device <NUM> can be simplified, and can be inexpensively manufactured.

A configuration of a crane 100E according to a fifth embodiment is different from the configuration according to the first to fourth embodiments in that a jib backstop operation detection device <NUM> for detecting whether or not the jib backstop <NUM> is in contact with a target (contact plate) <NUM> is disposed in the target <NUM> instead of the jib backstop <NUM>. Specifically, according to the fifth embodiment, instead of detecting the stretching operation of the jib backstop <NUM>, an upward-downward operation of the target <NUM> is detected so as to determine whether or not the jib backstop <NUM> is reliably in contact with the target <NUM>.

Referring to <FIG>, <FIG>, a configuration of the jib backstop operation detection device <NUM> according to the fifth embodiment will be described. <FIG> is a side view illustrating a main part near the target <NUM> of the crane 100E according to the fifth embodiment. <FIG> is an enlarged view of a part D in <FIG>, and <FIG> is a view taken along an arrow E in <FIG>.

As illustrated in <FIG>, <FIG>, according to the fifth embodiment, the jib backstop operation detection device <NUM> is disposed in the target <NUM>. According to the fifth embodiment, the jib backstop operation detection device <NUM> includes a base plate <NUM> to which a target limit switch <NUM> (third limit switch / hereinafter, abbreviated as a limit switch <NUM>) is attached, four coned disk springs (biasing members) <NUM> disposed at four corners between the base plate <NUM> and the target <NUM>, and four guide pins <NUM> to be inserted into the respective coned disk springs <NUM>.

The target <NUM> is formed of a square plate, is biased upward by the coned disk spring <NUM>, and is held at a predetermined interval from the limit switch <NUM> disposed in the base plate <NUM>. In other words, the limit switch <NUM> is disposed at a position separated downward from the target <NUM> as the predetermined interval. Here, the predetermined interval is preferably set to such a distance which enables the limit switch <NUM> to detect that the jib backstop <NUM> is reliably in contact with the target <NUM>, and can be set to a displacement difference L1, for example (refer to <FIG>). The target <NUM> is configured to be movable in the upward-downward direction with respect to the base plate <NUM> while being guided by the guide pin <NUM>.

If the jib <NUM> performs the standing operation to the position P1 from the position P1 where the other end 70b of the jib backstop <NUM> starts to come into contact with the target <NUM> (refer to <FIG>), in accordance with the standing operation of the jib <NUM>, the other end 70b of jib backstop <NUM> presses the target <NUM> downward. In this case, the target <NUM> is moved downward as much as a displacement amount L1 (third displacement amount) against the biasing force of the coned disk spring <NUM>, and presses down the roller <NUM> of the limit switch <NUM> so that the limit the contact of the limit switch <NUM> is closed and an ON-signal is output to the controller 200E. The ON-signal (operation signal) is input from the limit switch <NUM>, thereby enabling the controller 200E to detect that the jib backstop <NUM> is reliably in contact with the target <NUM>.

In this way, according to the fifth embodiment, the target <NUM> is pressed by the jib backstop <NUM> from an initial position where the jib backstop <NUM> is not in contact with the target <NUM>. When the jib backstop <NUM> reaches the third position where the jib backstop <NUM> is moved as much as the displacement amount L1 (third displacement amount), the limit switch <NUM> is configured to be turned on.

Next, a configuration of the controller 200E mounted on the crane 100E will be described. <FIG> is a block diagram illustrating an input to and an output from the controller 200E. The controller 200E according to the fifth embodiment is different from that according to the first embodiment in that limit switches <NUM> and 591R are connected to the input side instead of the limit switches <NUM> and 91R. The output side is the same as that according to the first embodiment. As will be described later, a configuration of an operation determination table 205E stored in a memory is different from that according to the first embodiment.

Next, the control of the derricking operation of the jib <NUM> which is performed by the controller 200E will be described. <FIG> is a flowchart illustrating a control procedure of the derricking operation of the jib <NUM> which is performed by the controller 200E. As illustrated in <FIG>, if the derricking operation of the jib <NUM> starts, the controller 200E acquires operation information of the jib backstop <NUM>, based on an operation signal output from the limit switch <NUM> (Step S1-<NUM>), and acquires angle data of the jib <NUM>, based on the detection signal from the jib angle sensor <NUM> (Step S2). Next, the controller 200E determines whether a relationship is normal between the operation of the jib backstop <NUM> and the angle of the jib <NUM> (Step S3-<NUM>). The operation determination table 205E for determining whether or not the operation of the jib backstop <NUM> is normal is stored in a memory of the controller 200E.

<FIG> is a view illustrating the operation determination table 205E which stipulates whether or not the operation of the jib backstop <NUM> is normal. The operation determination table 205E illustrated in <FIG> stipulates whether or not the operation of the jib backstop <NUM> is normal based on the jib angle θ and the limit switches <NUM> and 591R. Specifically, in a case where the angle (jib angle) θ of the jib <NUM> is smaller than <NUM>°, and in a case where both the limit switches <NUM> and 591R are turned off, it is stipulated that the operation of the jib backstop <NUM> is "normal". In a case where the jib angle is <NUM>° or larger, and only in a case where both the limit switches <NUM> and 591R are turned on, it is stipulated that the operation of the jib backstop <NUM> is "normal. In a case where at least any one of the limit switches <NUM> and 591R is turned off, it is stipulated that the operation of the jib backstop <NUM> is "abnormal".

In a case where the controller 200E determines that the operation is normal in the operation determination process in StepS3-<NUM> (S3-<NUM>/ Yes), the controller 200E performs the derricking operation of the jib <NUM> (Step S4). In a case where the controller 200E determines that the operation is abnormal (S3-<NUM> / N0) in the operation determination process in Step S3-<NUM>, the controller 200E proceeds to Step S6 so as to stop the derricking operation of the jib <NUM>. In this manner, the jib <NUM> is prevented from performing the standing operation in a state where the jib backstop <NUM> is not in contact with the target <NUM>. The subsequent process is the same as that according to in the first embodiment. Accordingly, the description will be omitted here.

In this way, similarly to the first to fourth embodiments, according to the fifth embodiment, the derricking operation of the jib <NUM> can also be performed by detecting that the jib backstop <NUM> surely is reliably in contact with the target <NUM>. Accordingly, the crane 100E can be safely operated. According to the fifth embodiment, a configuration is adopted in which the jib backstop operation detection device <NUM> is disposed in the target <NUM>. Accordingly, it is not necessary to improve the jib backstop <NUM> in the related art. That is, the crane in the related art can be more safely operated merely by installing the jib backstop operation detection device <NUM> according to the fifth embodiment in the target of the existing crane.

The present invention is not limited to the above-described embodiments, and can be modified in various ways within the scope not departing from the gist of the present invention. All of the technical matters included in the technical concept described in the appended claims are objects of the present invention. Although the above-described embodiments are preferred examples, those skilled in the art can realize various substitutes, corrections, modifications, or improvements, based on the contents disclosed in the specification, and these are included in the technical scope described in the appended claims.

For example, although not illustrated, a configuration may be adopted as follows. The jib backstop operation detection device includes a strain gauge for detecting distortion of the target <NUM>, and the controller determines that the angle of the jib <NUM> is a predetermined angle (for example, <NUM>°) or larger, based on the detection signal from the jib angle sensor <NUM>. In a case where the distortion of the target <NUM> is smaller than a predetermined threshold, based on a detection signal output from the strain gauge, the controller stops the standing operation of the jib <NUM>.

In the respective embodiments described above, a configuration may be adopted. One end 70a of the jib backstop <NUM> is the free end, and the other end 70b is pivotally supported by the tower <NUM>. In this case, the target <NUM> is disposed in the jib <NUM>. In the first embodiment and the second embodiment, the positions of the limit switch <NUM> and the limit switch 91R in the forward-rearward direction of may not necessarily be the same as each other. In this case, it may be determined that the jib backstop <NUM> is normal in a case where both the limit switches <NUM> and 91R are turned on. The operation of the jib backstop <NUM> may be determined by monitoring only the limit switch disposed forward between the limit switches <NUM> and 91R. In a case where the limit switch disposed forward is turned on, it can be considered that the limit switch disposed rearward is also turned on.

In the third embodiment and the fourth embodiment, the jib backstop operation detection devices <NUM> and <NUM> may include the limit switch <NUM> in order to prevent the jib from being excessively wound.

In the respective embodiments described above, a configuration has been described in which the derricking operation of the jib <NUM> is controlled, based on the operation signal which switches the contacts of the limit switches <NUM> and <NUM> from OFF to ON. However, the derricking operation of the jib <NUM> maybe controlled, based on the operation signal which switches the contacts of the limit switches <NUM> and <NUM> from ON to OFF.

Claim 1:
A crane (100A, 100B, 100C, 100D, 100E) comprising:
a front member (<NUM>) capable of derricking;
a backstop (<NUM>) disposed on a rear surface side of the front member (<NUM>) so as to limit a standing operation of the front member (<NUM>) as the front member (<NUM>) pivots upward from a horizontal position;
an angle sensor (<NUM>) configured to detect an angle of the front member (<NUM>);
an operation detection unit (<NUM>) configured to detect whether or not the backstop (<NUM>) is operated; and
a controller (200A, 200B, 200C, 200D, 200E) configured to control a derricking operation of the front member (<NUM>), characterized in that
in a case where the controller (200A, 200B, 200C, 200D, 200E) determines that the angle of the front member (<NUM>) is equal to or larger than a predetermined angle, based on a detection signal output from the angle sensor (<NUM>), and determines that the backstop (<NUM>) is not operated, based on a detection signal output from the operation detection unit (<NUM>), the controller (200A, 200B, 200C, 200D, 200E) is configured to stop the standing operation of the front member (<NUM>),
wherein one end (70a) of the backstop (<NUM>) is supported such that the one end (70a) of the backstop (<NUM>) is attached to the front member (<NUM>), and the other end (70b) of the backstop (<NUM>) is a free end such that the other end (70b) of the backstop (<NUM>) is not in contact with a contact portion (<NUM>) of the backstop (<NUM>) before performing the standing operation of the front member (<NUM>) and comes into contact with the contact portion (<NUM>) in accordance with the standing operation of the front member (<NUM>),
wherein the operation detection unit (<NUM>) is configured to detect whether or not the other end (70b) of the backstop (<NUM>) is in contact with the contact portion (<NUM>),
wherein the controller (200A, 200B, 200C, 200D, 200E) is configured to determine that the angle of the front member (<NUM>) is equal to or larger than the predetermined angle, based on the detection signal output from the angle sensor (<NUM>), and
wherein the controller (200A, 200B, 200C, 200D, 200E) is configured to stop the standing operation of the front member (<NUM>) in a case where it is determined that the other end (70b) of the backstop (<NUM>) is not in contact with the contact portion (<NUM>), based on the detection signal output from the operation detection unit (<NUM>).