JP3986592B2 - Multi-stage telescopic boom simultaneous telescopic device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a simultaneous telescopic device in a multistage telescopic boom used for a mobile crane or an aerial work vehicle.
[0002]
[Prior art]
As shown in FIG. 2, this type of multi-stage telescopic boom A is constructed by inserting the boom sections 2, 3, 4 on the distal end side into the boom sections 1, 2, 3 on the base end side so as to be extendable and retractable. The boom A is provided with a simultaneous telescopic device B for simultaneously extending and contracting between the boom sections.
[0003]
The simultaneous telescopic device B includes a plurality of hydraulic cylinders 5 and 6 interposed between different boom sections of the multistage telescopic boom A (in the example of FIG. 2, the hydraulic cylinder 5 interposed between the boom section 1 and the boom section 2). A hydraulic cylinder 6) interposed between the boom section 2 and the boom section 3, a direction switching valve 7 having a pair of control ports 7a and 7b, one control port 7a of the direction switching valve 7, and the plurality of hydraulic pressures. The extension operation side pressure oil circuit 9 that connects the extension operation side pressure oil chambers 5a and 6a of the cylinders 5 and 6 through the branch flow valve 8, the other control port 7b of the direction switching valve 7, and the plurality of expansion cylinders 5 and 5 respectively. 6 between the reducing operation side pressure oil chambers 5b and 6b, and between the oil collecting passages 8 and the oil passages 11 and 12 connecting the extension operation side pressure oil chambers 5a and 6a. A communication oil passage 14 connected via a valve 13, and by switching the direction switching valve 7 in a state where the communication oil passage 14 is blocked by the on-off valve 13, the plurality of hydraulic cylinders 5, 6 are simultaneously operated. The boom sections 1, 2, 3, and 4 of the multistage telescopic boom A are telescopically driven to extend and contract, and the communication oil passage 14 is opened by the on-off valve 13 so that the hydraulic cylinders 5 and 6 can extend and contract. The stroke position of the boom section to be adjusted is adjusted.
[0004]
In this example, there is a known wire rope type simultaneous expansion / contraction means between the boom sections 2, 3, 4 so that the expansion / contraction drive of the boom section 3 with respect to the boom section 2 drives the expansion / contraction of the boom section 4 with respect to the boom section 3. It is attached. Accordingly, the telescopic cylinder 5 drives the boom section 2 to extend and contract, and the telescopic cylinder 6 drives the boom sections 3 and 4 to extend and contract.
[0005]
This type of simultaneous expansion and contraction device extends the hydraulic cylinders 5 and 6 simultaneously by extending the direction switching valve 7 (switching the direction switching valve 7 to the A position) to simultaneously extend each boom section 2 of the expansion boom A. 4 to 4 at the same time are driven to extend, and the direction switching valve 7 is contracted (the direction switching valve 7 is switched to the low position), whereby the hydraulic cylinders 5 and 6 are simultaneously contracted to reduce each boom section of the telescopic boom A. 2 to 4 can be simultaneously reduced. In this case, the flow dividing valve 8 interposed in the extension operation side pressure oil circuit 9 diverts the amount of oil flowing from the one control port 7a of the direction switching valve 7 to each extension operation side pressure oil chamber 5a, 6a in a predetermined ratio, In addition, the amount of oil flowing from each of the extension operation side pressure oil chambers 5a, 6a to one control port 7a of the direction switching valve 7 is collected at a predetermined ratio. The ratio between the diversion flow and the current collection is designed so that the boom sections 3 and 4 expand and contract the entire effective stroke while the boom section 2 of the expansion boom A expands and contracts the entire effective stroke. .
[0006]
The on-off valve 13 is a solenoid-operated normally-closed on-off valve. The on-off valve 13 includes a boom section 2 that is extended and retracted by a hydraulic cylinder 5 when the multistage extendable boom A is extended or reduced. When the boom sections 3 and 4 driven to extend and contract by the hydraulic cylinder 6 do not fully extend or contract at the same time (caused by the divided flow error of the divided flow valve 8) (hereinafter referred to as "stroke end mismatch"), a manual operation switch By operating a and releasing it, both are fully expanded or contracted to effectively utilize the boom length of the multistage telescopic boom A.
[0007]
[Problems to be solved by the invention]
By the way, in the conventional simultaneous expansion and contraction device of the multistage telescopic boom, the on-off valve 13 is operated to open and close at the operator's discretion, but it is difficult for the operator to grasp the stroke end inconsistency. Even so, there is a problem that the opening / closing operation of the opening / closing valve 13 is troublesome.
[0008]
The present invention provides a simultaneous expansion / contraction device for a multistage expansion / contraction boom in which the on-off valve 13 is automatically opened when the stroke ends are mismatched, and an object of the present invention is to solve the above-mentioned problems of the prior art.
[0009]
[Means for Solving the Problems]
That is, the simultaneous expansion and contraction device for the multistage telescopic boom according to the first aspect of the present invention is a multistage expansion and contraction system in which the boom sections 2, 3 and 4 on the distal end side are sequentially inserted into the boom sections 1, 2 and 3 on the base end side so as to be extendable and contractible. A simultaneous expansion and contraction device B of boom A,
A directional control valve 7 having a pair of control ports 7a and 7b, one control port 7a of the directional control valve 7 and the extension operation side pressure oil chambers 5a and 6a of the plurality of hydraulic cylinders 5 and 6 are divided into flow collecting valves 8. Expansion operation side pressure oil circuit 9 connected via the other, the other control port 7b of the direction switching valve 7 and the reduction operation side pressure oil circuit 5b, 6b connecting the respective reduction operation side pressure oil chambers 5b, 6b of the plurality of expansion cylinders 5, 6. 10 and a communication oil passage 14 for connecting the oil collecting passage 11 and the oil passages 11 and 12 for connecting the extension operation side pressure oil chambers 5a and 6a via the on-off valve 13, respectively. By switching the direction switching valve 7 in a state where the communication oil passage 14 is shut off, the hydraulic cylinders 5 and 6 are simultaneously expanded and contracted to move between the boom sections 1, 2, 3 and 4 of the multistage telescopic boom A. Simultaneously opening and closing the valve In 3 which was configured to adjust the stroke position of the boom sections are telescopic driven by the respective hydraulic cylinders 5 and 6 by opening the communicating oil passage 14 by,
Boom length detection means for detecting that the length of the multi-stage telescopic boom A driven to extend and retract by the hydraulic cylinders 5 and 6 is in the vicinity of the extension end position or the reduction end position in the effective stroke is provided, and the direction switching is performed. An operation detecting means for detecting the operation of the valve 7 to the extension side or the operation to the reduction side is provided, the boom length detection means detects the position near the end of the extension stroke of the multistage extension boom A, and the operation detection means detects the extension operation. Or when the boom length detection means detects the position near the end of the reduction stroke of the multi-stage telescopic boom A and the operation detection means detects the reduction operation, the boom length detection means is opened so that the on-off valve 13 is opened. The operation detecting means and the on-off valve 13 are connected to each other.
[0010]
DETAILED DESCRIPTION OF THE INVENTION
An embodiment of a simultaneous expansion and contraction device for a multistage telescopic boom according to the present invention will be described with reference to FIG. The simultaneous expansion / contraction device for the multi-stage telescopic boom of the present invention is different from the simultaneous expansion / contraction device shown in FIG. The prior art described above is used.
[0011]
In FIG. 1, reference numeral 15 denotes a boom length detecting means for detecting that the length of the multistage telescopic boom A that is extended and retracted by the hydraulic cylinders 5 and 6 is close to the extension end position in the effective stroke of the multistage telescopic boom A. It is. The boom length detecting means 15 includes a cord winder 15a attached at an appropriate position of the boom section 1, and a cord 15b wound and energized by the cord winder 15a and having its tip connected to the tip of the boom section 4. The potentiometer 15c for detecting the rotation of the cord winder 15a, and detecting that the electrical signal from the potentiometer 15c has a value corresponding to the vicinity of the extension end position in the effective stroke of the multistage telescopic boom A is output. And an electric circuit 15d.
[0012]
Reference numeral 16 denotes operation detection means for detecting an operation of the direction switching valve 7 toward the extension side (operation of the direction switching valve to the position B) (in this example, the direction switching valve 7 is turned on when the corresponding state is reached. It is composed of limit switches linked to the control lever.
[0013]
The boom length detection means 15, the operation detection means 16 and the on-off valve 13 are detected when the boom length detection means 15 detects the vicinity of the extension end position in the effective stroke of the multistage telescopic boom A and the operation detection means 16 detects the extension operation. Are connected so that the on-off valve 13 is opened. That is, a switch 17 and an operation detection unit 16 that are connected and operated by a detection signal from the boom length detection unit 15 are interposed in series in an electrical path connecting the power source and the solenoid of the on-off valve 13.
[0014]
Next, the operation will be described. The directional switching valve 7 is operated to the extension side (operated to the A position), and the hydraulic cylinders 5 and 6 are simultaneously extended to drive the boom sections 2 to 4 of the telescopic boom A at the same time. When the driven multi-stage telescopic boom A reaches the vicinity of the extension end position in its effective stroke, the operation detecting means 16 detects the operation of the direction switching valve 7 toward the extension side, and the boom length detecting means 15 detects the multi-stage telescopic boom. Since the vicinity of the extension end position of A is detected, the on-off valve 13 is opened. Therefore, even if the stroke ends are mismatched, the multistage telescopic boom A that is driven to extend by the hydraulic cylinders 5 and 6 can be driven to extend to the full effective stroke.
[0015]
In the above embodiment, an example of dealing with the stroke end mismatch at the time of extension driving of the multistage telescopic boom A has been shown. It is detected that the position is close to the position, and the operation detection means 16 detects the operation of the direction switching valve 7 toward the reduction side, so that the stroke end mismatch at the time of reduction driving of the multistage telescopic boom A is detected. Of course, it can cope with. Further, by combining them, it is a matter of course that both the stroke end mismatch at the time of extension driving of the multistage telescopic boom A and the stroke end mismatch at the time of reduction driving can be dealt with.
[0016]
In addition to the above embodiment, the communication oil passage 14 may be provided with a throttle. Even when the on-off valve 13 is opened, the function of the flow collecting valve 8 remains, so that in the open state of the on-off valve 13, almost no flow occurs due to the difference in normal operating pressure, and the hydraulic cylinder on one side strokes. Only when the end is reached, the flow rate increases in the communication oil passage 14, and the other hydraulic cylinder is driven to extend. As a result, when the on-off valve 13 is opened when the stroke ends do not match, the operation is continued without any sense of incongruity as if the stroke end of one hydraulic cylinder is detected and automatically corrected.
[0017]
【The invention's effect】
The simultaneous expansion and contraction device of the multistage telescopic boom of the present invention constructed and operated as described above can automatically open the on-off valve 13 when the stroke end is not aligned, simply by adding a simple configuration to the conventional one. The telescopic boom A can be effectively used over the entire effective stroke.
[Brief description of the drawings]
FIG. 1 is an explanatory diagram of a simultaneous expansion and contraction device for a multistage expansion boom according to the present invention.
FIG. 2 is an explanatory view of a conventional simultaneous expansion and contraction device for a multistage expansion boom.
[Explanation of symbols]
A: Multistage telescopic boom, 1-4; Boom section, B: Simultaneous telescopic device,
5; telescopic cylinder, 5a; extension operation side pressure oil chamber, 5b; reduction operation side pressure oil chamber,
6; telescopic cylinder; 6a; extension operation side pressure oil chamber; 6b; reduction operation side pressure oil chamber;
7; Directional switching valve, 7a, 7b; Control port, 8;
9: Extension operation side pressure oil circuit, 10: Reduction operation side pressure oil circuit,
11, 12; oil passage, 13: on-off valve, 14: communication oil passage,
15; boom length detecting means, 15a; cord winder, 15b; cord;
15c; Potentiometer, 16; Operation detecting means, 17; Switch,
a: manual operation switch, a; expansion operation position, b; reduction operation position,

Claims (1)

A simultaneous telescopic device B for a multi-stage telescopic boom A, in which the boom sections 2, 3, and 4 on the distal end side are sequentially inserted into the boom section 1, 2, 3 on the proximal end side so as to be telescopically extendable,
A directional control valve 7 having a pair of control ports 7a and 7b, one control port 7a of the directional control valve 7 and the extension operation side pressure oil chambers 5a and 6a of the plurality of hydraulic cylinders 5 and 6 are divided into flow collecting valves 8. Expansion operation side pressure oil circuit 9 connected via the other, the other control port 7b of the direction switching valve 7 and the reduction operation side pressure oil circuit 5b, 6b connecting the respective reduction operation side pressure oil chambers 5b, 6b of the plurality of expansion cylinders 5, 6. 10 and a communication oil passage 14 for connecting the oil collecting passage 11 and the oil passages 11 and 12 for connecting the extension operation side pressure oil chambers 5a and 6a via the on-off valve 13, respectively. By switching the direction switching valve 7 in a state where the communication oil passage 14 is shut off, the hydraulic cylinders 5 and 6 are simultaneously expanded and contracted to move between the boom sections 1, 2, 3 and 4 of the multistage telescopic boom A. Simultaneously opening and closing the valve In 3 which was configured to adjust the stroke position of the boom sections are telescopic driven by the respective hydraulic cylinders 5 and 6 by opening the communicating oil passage 14 by,
Boom length detection means for detecting that the length of the multi-stage telescopic boom A driven to extend and retract by the hydraulic cylinders 5 and 6 is in the vicinity of the extension end position or the reduction end position in the effective stroke is provided, and the direction switching is performed. An operation detecting means for detecting the operation of the valve 7 to the extension side or the operation to the reduction side is provided, the boom length detection means detects the position near the end of the extension stroke of the multistage extension boom A, and the operation detection means detects the extension operation. Or when the boom length detection means detects the position near the end of the reduction stroke of the multi-stage telescopic boom A and the operation detection means detects the reduction operation, the boom length detection means is opened so that the on-off valve 13 is opened. A simultaneous expansion and contraction device for a multistage telescopic boom, characterized in that the operation detecting means and the on-off valve 13 are connected together.

Images