Patent Application
20150144583
This application claims the benefit of Japanese Patent Application No. 2013-243984, filed Nov. 26, 2013, which is incorporated herein by reference.
1. Technical Field
The present invention relates to a boom extending and retracting apparatus that extends and retracts a telescopic boom of a crane.
2. Related Art
A crane is equipped with a telescopic boom to lift goods. There has been known a telescopic boom in which a plurality of boom members are provided as to be slid with respect to each other and one telescopic cylinder is provided to slide the plurality of boom members one by one to extend. However, when the plurality of boom members are slid one by one with one telescopic cylinder, it may take time to extend or retract the telescopic boom. Therefore, in a crane disclosed in Patent Literature 1, a differential fluid circuit as well as a normal fluid circuit is provided for a fluid circuit to inject fluid such as hydraulic oil into the telescopic cylinder. By extending the telescopic cylinder with the action of the differential fluid circuit, it is possible to increase the extension speed of the telescopic cylinder. Therefore, it is possible to shorten the extension time of the telescopic boom, and possible to improve the convenience.
However, in Patent literature 1, an additional switch is used to change and select an activated one between the differential fluid circuit and the normal fluid circuit. In this case, in the course of the work, the operator of the crane always has to know and identify the selected and using circuit from the differential fluid circuit and the normal fluid circuit, while executing a complex crane operation of the telescopic boom. And, the operator has to flip the additional switch during the work repeatedly, in accordance with and based on the emphasizing usage state. Therefore, management items during the work are increased, and consequently the burden on the operator increases.
Thus, in a crane, both to reduce the burden on the operator and to improve the convenience of the telescopic boom are required to be realized.
The boom extending and retracting apparatus according to the present invention includes: a telescopic boom including a plurality of boom members that can slide with respect to each other; a telescopic cylinder configured to extend and retract the telescopic boom by sliding the plurality of boom members, the telescopic cylinder including: a cylinder tube having an internal space filled with fluid; and a piston rod having piston dividing the internal space of the cylinder tube into an extension-side oil chamber and a retraction-side oil chamber, the piston rod moving along an inner surface of the cylinder tube to extend and retract the telescopic cylinder; a fluid circuit including a normal fluid circuit and a differential fluid circuit, the normal fluid circuit injecting fluid only into the extension-side oil chamber of the telescopic cylinder, and the differential fluid circuit injecting the fluid into the extension-side oil chamber while the fluid in the retraction-side oil chamber can be moved to the extension-side oil chamber; a controller configured to choose one of the normal fluid circuit and the differential fluid circuit, in order to extend and retract the telescopic boom; and an operating lever turned from a neutral position in order to extend the telescopic boom, wherein after the operating lever is turned to an extension side and the controller starts extending the telescopic boom using the differential fluid circuit, when the operating lever is turned to the extension side again via the neutral position, the controller chooses the normal fluid circuit to extend the telescopic boom using the normal fluid circuit.
Preferably, the boom extending and retracting apparatus of the crane further including a detection member configured to detect an extension amount of the telescopic cylinder, wherein, in a case where the controller determined an interruption of the extension of the telescopic boom based on the detected extension amount by the detection member before the operating lever is turned back to the neutral position, the controller chooses the normal fluid circuit to extend the telescopic boom using the normal fluid circuit.
Preferably, the boom extending and retracting apparatus of the crane further including a timer configured to measure a repeated operation time that has counted from a turned back timing of the operating lever to the neutral position until the repeated operation of the operating lever to the extension side, wherein: when the repeated operation time is shorter than a predetermined period of time, the controller chooses the normal fluid circuit based on the repeated operation of the operating lever to the extension side, and changes the extension of the telescopic boom with using the normal fluid circuit; and when the repeated operation time is equal to or longer than the predetermined period of time, the controller chooses the differential fluid circuit based on the repeated operation of the operating lever to the extension side, and continues the extension of the telescopic boom with using the differential fluid circuit.
Preferably, the boom extending and retracting apparatus of the crane further including a switch configured to set an availability or unavailability of the differential fluid circuit, wherein, when the operating lever is repeatedly operated to the extension side, the controller chooses the normal fluid circuit regardless of the setting of the switch, and changes the extension of the telescopic boom with using the normal fluid circuit.
Preferably, the boom extending and retracting apparatus of the crane further including a display member configured to display the activated function of the fluid circuit between the normal fluid circuit and the differential fluid circuit.
With the present invention, when the operating lever was operated from the neutral position in the extension side as for the telescopic boom to be started to be extended with using the differential fluid circuit and then the operating lever is again operated in the extension side, the control part selects the normal fluid circuit mode. That is, the activating mode of the fluid circuit is switched from the differential fluid circuit to the normal fluid circuit. The operator can switch the activating mode of the fluid circuit just by turning the operating lever repeatedly in the extension side. Therefore, with the present invention, it is possible to achieve an improved convenience in which the normal fluid circuit and the differential fluid circuit can be used switchably to extend the telescopic boom. In addition, it is possible to realize the intuitively knowable handleability in which the operating lever is only and repeatedly operated in the extension side, and therefore to reduce the burden of the operator. Moreover, there is no need to provide any additional switch to flip the fluid circuit during the work, and therefore it is possible to reduce the cost for the switch and also to save the space for installing the switch.
Hereinafter, embodiments of the present invention will be described with reference to the drawings.
The crane apparatus 3 includes a swivel base 11, a telescopic boom 13 incorporating a telescopic cylinder 12 in
The swivel base 11 is provided on the frame of the vehicle 2. The swivel base 11 horizontally rotates upon the frame which is held in an approximately horizontal level.
The telescopic boom 13 employs a mechanism to extend and retract multiple boom members with one telescopic cylinder 12. The telescopic boom 13 includes a plurality of boom members 21. Each of the plurality of boom members 21 has a polygonal and cylindrical shape which is similar to each other therebetween, and is inserted into the outer accommodating boom members 21 as to form a nested configuration. In this nested state, each of the inside boom member 21 slides out from each of the outside boom member 21, and therefore the telescopic boom 13 extends. When the number of the nested boom members 21 is six, they are referred to as, in the order from the outside, a base boom member 21A, a second boom member 21B, a third boom member 21C, a fourth boom member 21D, a fifth boom member 21E, and a top boom member 21F. The base end of the base boom member 21A, which is the outmost boom member of the telescopic boom 13, is provided on the swivel base 11 and can be raised and lowered. By this means, the telescopic boom 13 can horizontally rotate together with the swivel base 11 on the frame of the vehicle 2, and can be raised and lowered by a boom cylinder with respect to the swivel base 11. In addition, the telescopic boom 13 can be extended and retracted. The operator gets in the cabin 16 of the mobile crane 1 and operates an operating part 91 in
The telescopic cylinder 12 is provided into the telescopic boom 13. The telescopic cylinder 12 is provided at the inside of the top boom member 21F. The telescopic cylinder 12 includes a long cylinder tube 31 and a piston rod 32. As described later in
In the base end side of the cylinder tube 31, an interlock mechanism 35 and a connecting pin 36 are provided. As the telescopic cylinder 12 extends and retracts and the cylinder tube 31 moves in the longitudinal direction of the telescopic cylinder 12, the connecting pin 36 moves to the respective positions corresponding to the second connecting hole 23B, the third connecting hole 23C, the fourth connecting hole 23D, the fifth connecting hole 23E, and the top connecting hole 23F. The connecting pin 36 is connected to the corresponding connecting hole 23 of the boom member 21, by the action of the hydraulic circuit 14. In addition, in a state when the connecting pin 36 is positioned and connected to one of the connecting holes 23 of the boom members 21, the interlock mechanism 35 is placed at the corresponding position of the slender lock mechanism that is corresponding to the connecting holes 23 in the same boom member 21. In a case when the interlock mechanism 35 is placed in the corresponding position and the cylinder lock mechanism is locked, the boom side lock mechanism 22 can be detached from the outside next boom member 21. In other case, the boom side lock mechanism 22 is connected to the outside next boom member 21. In addition, the connecting pin 36 is removed from the connecting hole 23 by the action of the hydraulic circuit 14. Prior to that, the boom side lock mechanism 22 is connected to the outside next boom member 21 at the position in which the interlock mechanism 35 is detached. The boom member 21 is usually connected to the outside next boom member 21, and is disconnected from the outside next boom member 21 only when the connecting pin 36 is inserted into the connecting hole 23 as to be connected to the base end of the cylinder tube 31.
Then, for example in a state where the connecting pin 36 is connected to the top connecting hole 23F and the top lock mechanism 22F is released, when hydraulic pressure is applied to the extension-side oil chamber 33 by the action of the hydraulic circuit 14, the top boom member 21F slides from the position shown in
Here, in the boom side lock mechanism 22, when the interlock mechanism 35 is separated as to be able to move, by the action of the hydraulic circuit 14, a fixing pin 24 in
On the base end of the base boom member 21A of the telescopic boom 13, a detection member 96 is provided to detect an extension amount of the telescopic cylinder 12. The detection member 96 includes a detection reel 96A and a detection wire 96B. The detection reel 96A is rotatably provided on the base end of the base boom member 21A. The detection wire 96B is wound around the detection reel 96A. The front end of the detection wire 96B is fixed to the interlock mechanism 35 of the telescopic cylinder 12. When the interlock mechanism 35 moves to the front end side together with the cylinder tube 31, the detection wire 96B is drawn from the detection reel 96A. Meanwhile, when the interlock mechanism 35 moves to the base end side together with the cylinder tube 31, the detection wire 96B is wound around the detection reel 96A. The rotation amount of the detection reel 96A corresponds with the extension amount of the telescopic cylinder 12. The detection member 96 detects the rotation amount of the detection reel 96A, and outputs the detection result to a control part 93 of the hydraulic control system 15 described later. The control part 93 can calculate the extension length of the telescopic boom 13, based both on information of the boom side lock mechanism 22 which is connected with the interlock mechanism 35 and the detected value of the detection member 96.
The cylinder hydraulic circuit 43 extends and retracts the telescopic cylinder 12. The cylinder hydraulic circuit 43 includes a first supply path 51, a flow control valve 52, a pilot switching valve 53, a second supply path 54, a counter balance valve 55, a first circulation path 56, a hydro switching valve 57, a second circulation path 58, a bypass path 59, and a third circulation path 60. The first supply path 51 connects between the hydraulic pump 41 and the pilot switching valve 53. The flow control valve 52 is provided in the middle of the first supply path 51. The second supply path 54 connects the pilot switching valve 53 to the extension-side oil chamber 33 of the telescopic cylinder 12. The counter balance valve 55 is provided in the middle of the second supply path 54. The first circulation path 56 connects between the retraction-side oil chamber 34 of the telescopic cylinder 12 and the hydro switching valve 57. The second circulation path 58 connects between the hydro switching valve 57 and the pilot switching valve 53. The third circulation path 60 connects between the pilot switching valve 53 and the tank 42. The bypass path 59 connects between the hydro switching valve 57 and the second supply path 54. The flow control valve 52 adjusts the flow rate or the pressure of the hydraulic oil which is supplied from the hydraulic pump 41 to the pilot switching valve 53.
The pilot switching valve 53 switches the state of the telescopic cylinder 12, among extension, stop, and retraction. The pilot switching valve 53 has three switched states corresponding to three blocks shown in
The hydro switching valve 57 has two switched states in which the cylinder hydraulic circuit 43 is switched between a normal hydraulic circuit mode and a differential hydraulic circuit mode. In the switching state corresponding to the left block in
In order to function the cylinder hydraulic circuit 43 as the normal hydraulic circuit to extend the telescopic cylinder 12, the pilot switching valve 53 is switched to the extension state corresponding to the top block shown in
In order to function the cylinder hydraulic circuit 43 as the differential hydraulic circuit to extend the telescopic cylinder 12, the pilot switching valve 53 is switched to the extension state corresponding to the top block shown in
In the differential hydraulic circuit mode, the hydraulic oil in the retraction-side oil chamber 34 of the telescopic cylinder 12 is supplied to the extension-side oil chamber 33. Differently from the normal hydraulic circuit mode, there is no need to inject the hydraulic oil in the retraction-side oil chamber 34 to the tank 42. Almost all of the applied pressure to the extension-side oil chamber 33 by the hydraulic pump 41 is used to extend the telescopic cylinder 12. Thus, the piston rod 32 can move at a higher speed than in the normal hydraulic circuit mode within the internal space of the cylinder tube. Therefore, the telescopic boom 13 is extended at a high speed.
In order to function the cylinder hydraulic circuit 43 as the hydraulic circuit 14 to retract the telescopic cylinder 12, the pilot switching valve 53 is switched to the retraction state described as the bottom side block in
The connecting hydraulic circuit 44 drives the connecting pin 36, and controls the connection and disconnection between the connecting pin 36 and the connecting hole 23. The connecting hydraulic circuit 44 includes a third supply path 71, a second solenoid switching valve 72, a fourth supply path 73, a first drive cylinder 74 of the connecting pin 36, a fourth circulation path 75 and a fifth circulation path 76.
The third supply path 71 connects between the hydraulic pump 41 and the second solenoid switching valve 72. The fourth supply path 73 connects between the second solenoid switching valve 72 and the extension-side oil chamber of the first drive cylinder 74 for the connecting pin 36. The fourth circulation path 75 connects between the retraction-side oil chamber of the first drive cylinder 74 for the connecting pin 36 and the second solenoid switching valve 72. The fifth circulation path 76 connects between the second solenoid switching valve 72 and the tank 42. The second solenoid switching valve 72 switches the connecting state between the connecting pin 36 and the connecting hole 23, among connection, stop and disconnection. The second solenoid switching valve 72 has three switching states. In the connection state in the right side block of
For the connecting pin 36 provided in the cylinder tube 31 being engaged with and connected to the connecting hole 23 provided in the boom member 21, the second solenoid switching valve 72 is switched to the connection state described in the right side block of
The fixing hydraulic circuit 45 fixes the boom members 21 to each other, and releases the fixed state. The fixing hydraulic circuit 45 includes the third supply path 71, a third solenoid switching valve 77, a fifth supply path 78, a second drive cylinder 79 of the fixing pin 24, a sixth circulation path 80 and a fifth circulation path 76.
The third supply path 71 connects between the hydraulic pump 41 and the third solenoid 77. The fifth supply path 78 connects between the third solenoid switching valve 77 and the extension-side oil chamber 33 of the second drive cylinder 79 for the fixing pin 24. The sixth circulation circuit 80 connects between the retraction-side oil chamber 34 of the second drive cylinder 79 for the fixing pin 24 and the third solenoid switching valve 77. The fifth circulation path 76 connects between the second solenoid switching valve 72 and the tank 42. The third solenoid switching valve 77 switches the state of the fixing pin 24, among connection, stop and disconnection. The third solenoid switching valve 77 has three switching state. In the connection state described in the right side block of
For the fixing pin 24 of the boom member 21 being engaged with the fixing hole 25 of the outside next boom member 21, the third solenoid switching valve 77 is switched to the connected state described in the right side block of
The hydraulic control system 15 in
The operating part 91 outputs a signal to operate the mobile crane 1 to the control part 93, based on the operation of the operator.
The detection part 92 detects the operating state of the mobile crane 1, and outputs a detection signal to the control part 93. The detection part 92 has various detection sensors that detect the length and the boom angle of the telescopic boom 13, and the swivel angle of the swivel base 11. The detection part 92 in
The display part 94 displays the operating state and the action state of the mobile crane 1, based on a display signal from the control part 93. The display part 94 includes a liquid crystal monitor, a lamp and so forth. The liquid crystal monitor provided in the cabin 16 shown in
The control part 93 is a controller, and may be a microcomputer including a CPU, a memory and so forth. The operating part 91, the detection part 92 and the display part 94 are connected to the control part 93. The control part 93 is connected to the hydraulic circuit 14. The control part 93 switches a plurality of switching valves in the hydraulic circuit 14. With the present embodiment, default data 97 and an interruption flag 98 are stored in the memory of the control part 93. In the default data 97, setting data is included for the differential hydraulic circuit to be used in the extension operation of the telescopic boom 13. The interruption flag 98 is placed when the extension of the telescopic boom 13 is interrupted during the extension control of the telescopic boom 13. The interruption flag 98 is used in the extension control of the telescopic boom 13. Here, the control part 93 may be provided in the AML of the cabin 16. Alternatively, the control part 93 may be provided in the other location within the vehicle 2.
Next, the extension control of the telescopic boom 13 in the mobile crane 1 of
For the telescopic boom 13 to be extended with using the differential hydraulic circuit, the operator operates the telescopic operating lever 95 by tilting it forward from the neutral position P1. The operating part 91 outputs a command signal for extending the telescopic boom 13 to the control part 93, based on the operation of the telescopic operating lever 95. Upon receiving the command signal for extending the telescopic boom 13 (step ST1), the control part 93 determines the presence or absence of the interruption flag 98 (step ST 2), and reads the default data 97 (step ST3). The control part 93 starts the extension control with using the differential hydraulic circuit, based on the default data 97 (step ST4).
In the extension control with using the differential hydraulic circuit, the control part 93 firstly controls and sets the connecting hydraulic circuit 44 as to connect the connecting pin 36 provided in the cylinder tube 31 to the top connecting hole 23F, and to disconnect the top boom member 21F from the outside next fifth boom member 21E. Next, the control part 93 switches the pilot switching valve 53 of the cylinder hydraulic circuit 43 from the stop state described as the middle block of
After extending the top boom member 21F, the control part 93 continuously performs the extend control of the fifth boom member 21E. The control part 93 retracts the telescopic cylinder 12, which has been separated from the top connecting hole 23F. The control part 93 switches the state of the pilot switching valve 53 of the cylinder hydraulic circuit 43 to the retraction state described in the bottom side block of
The control part 93 sequentially performs the extension control of the forth boom member 21D, the third boom member 21C, and the second boom member 21B in the order, in the same way as that of the top boom member 21F.
When the telescopic boom 13 is extended in a desired length, the operator turns the telescopic operating lever 95 from the extension side back to the neutral position P1. The operating part 91 outputs a stop signal of the extension of the telescopic boom 13 to the control part 93, based on the operation of the telescopic operating lever 95. Upon receiving the stop signal of the extension of the telescopic boom 13, the control part 93 performs the flow shown in
As described above, the control part 93 performs the above steps for the extension control, during the period after the telescopic operating lever 95 is turned from the neutral position P1 until being turned back to the neutral position P1. By this extension control, the telescopic boom 13 is extended to the length at the time the telescopic operating lever 95 is turned back to the neutral position P1.
Meanwhile, when the cylinder hydraulic circuit 43 functions as the differential hydraulic circuit to extend the telescopic cylinder 12, it is possible to increase the extension speed of the telescopic cylinder 12 as described above. However, in this case, the power to extend the telescopic cylinder 12 is not enough depending on the extension condition of the extension of the telescopic boom 13, for example, and therefore the telescopic cylinder 12 is likely to stop during the differential hydraulic circuit mode. If so, the extension of the telescopic boom 13 is interrupted, and therefore it is not possible to extend the telescopic boom any longer.
When this interruption is occurred during the extension control of the telescopic boom 13 using the differential hydraulic circuit, the operator turns the extension side telescopic operating lever 95 in the back to the neutral position P1, and turns again the telescopic operating lever 95 to the extension side. Hereinafter, the control based on the repeating operation will be described.
When the interruption of the extension of the telescopic boom 13 occurs during the control of the extension of the telescopic boom 13 using the differential hydraulic circuit, and then the telescopic operating lever 95 is turned from the extension side back to the neutral position 21, the control part 93 performs the control flow of
After the interruption of the extension occurred during the extension control of the telescopic boom 13 using the differential hydraulic circuit, when the telescopic operating lever 95 is operated again, the control part 93 determines whether or not a command signal is received for extension, which was generated based on the operation of the telescopic operating lever 95, according to the control flow of
As described above, in a state after the interruption of the extension occurred during the control of the extension of the telescopic boom 13 using the differential hydraulic circuit and where the telescopic operating lever 95 is turned again to the extension side, the control part 93 allows the cylinder hydraulic circuit 43 to function as the normal hydraulic circuit, regardless of the default setting. Therefore, even in a case where the cylinder hydraulic circuit 43 functions as the differential hydraulic circuit and where the extension power of the telescopic cylinder 12 is not enough, and therefore the extension of the telescopic cylinder 12 is interrupted, it is possible to extend the telescopic cylinder 12 with the cylinder hydraulic circuit 43 in the normal hydraulic circuit mode. In this way, the extension of the telescopic cylinder 12 is restarted, and therefore it is possible to extend the telescopic boom 13 to a desired length.
As described above, with the present embodiment, in the case in which the telescopic operating lever 95 is turned back to the neutral position P1 during the extension of the telescopic boom 13 using the differential hydraulic circuit and then is turned again to the extension side, the control part determines that interruption of the extension of the telescopic boom 13, based on the detected extension amount by the detection member 96 before the telescopic operating lever 95 is tuned to the neutral position 91, and selects the normal hydraulic circuit mode. By this means, the extension control of the telescopic boom 13 is switched from the control using the differential hydraulic circuit to the control using the normal hydraulic circuit. Therefore, for example, in a case where the extension of the telescopic boom 13 was interrupted during the extension control with using the differential hydraulic circuit and then the telescopic operating lever 95 is turned again to the extension side via the neutral position P1, the control part 93 automatically switches the mode of the cylinder hydraulic circuit 43 for extending the telescopic boom 13 from the differential hydraulic circuit mode to the normal hydraulic circuit mode, and therefore to restart the extension of the telescopic boom 13. By this means, even in a case where the action as the differential hydraulic circuit cannot provide enough power to extend the telescopic boom 13, it is possible to extend the telescopic boom 13 by the strong power with the normal hydraulic circuit. Therefore, it is possible to realize both of the high speed extension of the telescopic boom 13 and the reliable extension in which the telescopic boom 13 can extend in any extending state.
Moreover, the operator can switch the mode of the hydraulic circuit 14 only by turning again the telescopic operating lever 95 to the extension side. The operator is not required to recognize and to distinguish in the every aspect of the operation, between the acting state as the differential hydraulic circuit and the acting state as the normal hydraulic circuit. For example, when the operator has confirmed the interruption of the extension and turns the telescopic operating lever 95 again intuitively to the extension side, the mode of the hydraulic circuit 14 is automatically switched, and the extension of the telescopic boom 13 is restarted therewith. When the cylinder hydraulic circuit 43 can function as the differential hydraulic circuit and the normal hydraulic circuit, operator intrinsically always required to know which of the modes is used as the cylinder hydraulic circuit 43. However, it is not required to concern it with the present embodiment. Therefore, the controlling items during the operation of the crane 1 are not increased. Then, the operator does not required to emphasis the mode of the cylinder hydraulic circuit 14 in use, and can select unconsciously the proper mode of the cylinder hydraulic circuit 14 to extend the telescopic boom 13 with the intuitive and simply operation of the telescopic operating lever. Moreover, an additional switch is not required for changing the mode of the hydraulic circuit 14 during the work. By this means, the burden on the operator of the crane apparatus 3 is not increased. The operator can concentrate on the essential operations of the crane.
As a result, with the present embodiment, it is possible to improve the convenience of the telescopic boom 13 while reducing the burden on the operator. In addition, an additional switch does not need to change the mode of the cylinder hydraulic circuit 43 in the hydraulic circuit 14, and therefore it is possible to eliminate the cost for the switch and save the space in which the switch is installed.
With the present embodiment, the detection member 96 is provided for detecting the extension amount of the telescopic cylinder 12, and the control part 93 determines the interruption of the extension of the telescopic boom 13 during the extension of the telescopic boom 13 using the differential hydraulic circuit. Therefore, the control part 93 can determines the situation where the extension power is not enough to extend the telescopic boom 13 during the extension of the telescopic boom 13 using the differential hydraulic circuit, based on the detection result of the detection member 96 for detecting the extension amount of the telescopic cylinder 12. Here, the control part 93 may determine the interruption of the extension of the telescopic boom 13, based on a detection signal from a component other than the detection member 96. For example, the control part 93 may determine the interruption of the extension of the telescopic boom 13, based on a detection signal from a detection member for detecting the stop of the extension of the telescopic boom 13.
Next, the boom extending and retracting apparatus according to Embodiment 2 will be described. The basic configurations and the actions of the mobile crane 1 and the boom extending and retracting apparatus are the same as in Embodiment 1, and therefore the same reference numerals are assigned and overlapping description will be omitted. Hereinafter, the difference from Embodiment 1 will be mainly described.
The operating part 91 of the hydraulic control system 15 has a differential changeover switch 111 to select and to set the usage of the differential hydraulic circuit mode. The differential changeover switch 111 can selects between the using mode of the differential hydraulic circuit and the un-using mode of the differential hydraulic circuit. The differential changeover switch 111 outputs a mode signal according to the selected mode to the control part 93. Here, the differential changeover switch 111 may be disposed in the cabin 16. The differential changeover switch 111 may be provided as one of the switches 103 (see
The control part 93 includes a timer 112. The timer 112 may be incorporated into the microcomputer as a control part. The timer 112 measures the elapsed time after the telescopic operating lever 95 being turned back to the neutral position P1.
Here, the controlling flowcharts in
When the extension of the telescopic boom 13 was interrupted during the extension control of the telescopic boom 13 using the differential hydraulic circuit and then the telescopic operating lever 95 is turned from the extension side back to the neutral position P1, the control part 93 determines that the extension of the telescopic cylinder 13 is interrupted, based on the control flow of
After that, when the telescopic operating lever 95 set in the neutral position P1 is tuned to the extension side again, the control part 93 determines that an extension command signal is received based on the operation of the telescopic operating lever 95 (step ST1), according to the control flow of
Next, the control part 93 acquires the setting of the differential changeover switch (step ST22). Then, the control part 93 performs and determines the operation mode whether the differential hydraulic circuit mode is adopted or not, based on the acquired setting of the differential changeover switch 111 (step ST23). Here, the differential change over switch 111 is set in the differential side to adopt the differential hydraulic circuit mode, for example. In this mode, the differential hydraulic circuit is activated and used. In this case, the control part 93 determines whether or not the acquired repeated operation time T1 is shorter than a predetermined period of time (step ST24). The predetermined period of time is 10 seconds, for example. The predetermined period of time may be some seconds other than 10 seconds, or be in a time by minutes.
When the repeated operation time T1 is shorter than the predetermined period of time, the control part 93 operates the cylinder hydraulic circuit 43 in the normal hydraulic circuit mode (step ST5). Here, the telescopic operating lever 95 is immediately turned again to the extension side, the cylinder hydraulic circuit 43 is operated in the normal hydraulic circuit mode. By the action of the normal hydraulic circuit, the telescopic cylinder 12 is extended. Therefore, in the case in which the telescopic operating lever 95 is tuned to the extension side again in shortly after the interruption of the extension of the telescopic boom 13, the control part 93 operates the cylinder hydraulic circuit 43 in the normal hydraulic circuit mode. The control part 93 operates the cylinder hydraulic circuit 43 in the normal hydraulic circuit, regardless of the setting of the differential changeover switch 111. Therefore, even in the case where the cylinder hydraulic circuit 43 is operated in the differential hydraulic circuit mode, the extension power for the telescopic cylinder 12 is not enough, and therefore the extension of the telescopic cylinder 13 is interrupted, it is possible to extend the telescopic cylinder 12 by using the normal hydraulic circuit. It is possible to restart the extension of the telescopic boom 13 that has been interrupted, and therefore to extend the telescopic boom 13 from the interrupted length to a desired length.
Next, the other differences between Embodiment 1 and Embodiment 2 will be further described, regarding the normal extension control of the telescopic boom 13 according to Embodiment 2. In order to extend the telescopic boom 13, the operator operates the telescopic operating lever 95 to be tilted forward, that is, tilted from the neutral position 91 to the extension side. According to the control flow of
When the setting of the differential changeover switch 111 is in the differential hydraulic circuit mode, the control part 93 performs the extension control with using the differential hydraulic circuit in the same way as in Embodiment 1 (step ST4). The control part 93 extends the telescopic boom 13, as switching the mode of the cylinder hydraulic circuit 43 between the normal hydraulic circuit and the differential hydraulic circuit. As a result, the telescopic boom 13 is extended at a high speed. Meanwhile, the setting of the differential changeover switch 111 is not in the differential hydraulic circuit mode, the control part 93 performs the extension control with using only the normal hydraulic circuit mode (step ST5). The control part 93 extends the telescopic boom 13 with the activated normal hydraulic circuit mode. The telescopic boom 13 extends at a normal speed.
In a case where the differential changeover switch 111 is set in “differential mode” which means that the differential hydraulic circuit mode is adopted, the cylinder hydraulic circuit 43 can function as the differential hydraulic circuit as described as “differential output ON” in the first row of
In the case in which the differential changeover switch 111 is not set as the differential hydraulic circuit mode, the cylinder hydraulic circuit 43 cannot function as the differential hydraulic circuit and functions as the normal hydraulic circuit as shown as “normal mode” in the second row of
As described above, with the present embodiment, when the extension of the telescopic boom 13 using the differential hydraulic circuit was interrupted, and then the telescopic operating lever 95 is turned again to the extension side, the control part 93 adopts the normal hydraulic circuit mode, based on the repeated operation time T1 after the telescopic operating lever 95 is turned back to the neutral position P1 until the telescopic operating lever 95 is turned to the extension side again. Therefore, it is possible to restart the interrupted extension of the telescopic boom 13 during the extension of the telescopic boom 13 using the differential hydraulic circuit mode, and therefore to extend the telescopic boom 13 to a desired length. Moreover, in a case where the telescopic boom 13 is started to be extend, the repeated operation time T1 is usually longer than the predetermined period of time, and thus the control part 93 can adopts the differential hydraulic circuit mode based on the operation of the telescopic operating lever 95. By this means, it is possible to extend the telescopic boom 13 at a high speed. As described above, with the present embodiment, the timer 112 measures the elapsed time as the repeated operation time T1 from the telescopic operating lever 95 being turned back to the neutral position P1 until the telescopic operating lever 95 being turned again to the extension side, and therefore it is possible to adopt an appropriate mode of the cylinder hydraulic circuit 43 depending on the working situation.
In addition, with the present embodiment, the operating part 91 has the differential changeover switch 111 that sets the availability or unavailability of the differential hydraulic circuit mode. Therefore, the operator can set the availability or unavailability of the differential hydraulic circuit mode by using the differential changeover switch 111. By this means, it is possible to choose whether or not the differential hydraulic circuit mode is used. Moreover, when the telescopic operating lever 95 is turned to the extension side again after the extension of the telescopic boom 13 using the differential hydraulic circuit mode was interrupted, the control part 93 adopts the normal hydraulic circuit mode, regardless of the setting of the differential changeover switch 111, based on the repeated operation of the telescopic operating lever 95 in the extension side. As a result, it is possible to restart the extension of the telescopic boom 13 which was interrupted. Therefore, with the present embodiment, the operator can choose and set the usage of the differential hydraulic circuit mode with the differential changeover switch 111, without reducing the convenience for the operator to be able to switch the mode of the cylinder hydraulic circuit 43 by turning the telescopic operating lever 95 to the extension side again during the extension of the telescopic boom 13. In this way, it is possible to set the availability or unavailability of the differential hydraulic circuit mode by using the differential changeover switch 111. Therefore, in a case when a delicate work is required where the telescopic boom 13 has to be extended at a low speed from the beginning, for example, it is possible to prevent the telescopic boom 13 from extending at a high speed with the differential hydraulic circuit. Therefore, it is possible to execute each of crane works at appropriate speeds depending on the working situations.
Although the preferred embodiments have been explained, it is by no means limiting, but it will be appreciated that various modifications and alternations are possible within the scope of the invention.
For example, with the above-described embodiments, in the step ST13 of
With the above-described embodiments, in the hydraulic circuit 14, the cylinder hydraulic circuit 43 functions as the normal hydraulic circuit and the differential hydraulic circuit. In addition to this, the hydraulic circuit 14 may include the normal hydraulic circuit and the differential hydraulic circuit as separate hydraulic circuits.
With the above-described embodiments, the telescopic cylinder 12 is driven by the hydraulic circuit 14 using hydraulic oil. In addition to this, the telescopic cylinder 12 may be driven by fluid other than hydraulic oil, for example.
In this case, the cylinder fluid circuit that applies the fluid force to the telescopic cylinder 12 may function as a normal fluid circuit and a differential fluid circuit.
With the above-described embodiments, the plurality of boom members 12 in the telescopic boom 13 have similar polygonal and cylindrical shapes, and are nested one another in which each of the boom members 21 is inserted and accommodated in the respective outside next boom members 21. In addition to this, the plurality of boom members 21 may have similar U-shaped cross sections, and may be overlaid and nested one another. Moreover, although with the above-described embodiments, all of the boom members 21 are driven by a single telescopic cylinder 12. A plurality of telescopic cylinder 12 may be selectively used to drive the plurality of boom members 21.
The above-described embodiments are examples in which the boom extending and retracting apparatus according to the present invention is applied to the mobile crane 1. In addition to this, the boom extending and retracting apparatus may be applied to a tower crane and a fixed crane apparatus.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2013-243984 | Nov 2013 | JP | national |
