JPH022001B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a multistage telescopic boom used for cranes and the like.

For example, as a conventional multi-stage telescopic boom,
There is something like -15797. That is, in this multi-stage telescopic boom, a pin device is used as a means for locking the intermediate boom to the base boom when the intermediate boom is extended. is configured to insert and lock. However, in reality, with such a structure, the boom is long and it is extremely difficult to position and manufacture the boom so that the respective engagement holes coincide with each other. In addition, when the pin is removed when the boom is retracted, a force in the direction of retraction is also applied to the intermediate boom, so at the moment the pin is removed, it is subjected to an extremely large shearing force, causing damage to the shape of the pin. Often.

In addition, in this multi-stage telescopic boom, an oil passage switching valve that switches the oil passage to the next cylinder unit is provided between the booms, so the extension end position of the cylinder unit and the switching operation position of this oil passage switching valve are different. This oil passage switching valve had to be mounted on the boom to match, and it was extremely difficult to set the mounting position accurately in actual manufacturing.

Therefore, in the present invention, in order to solve the above problem, the boom is locked by a wedge device that uses frictional force instead of a pin device to solve the former problem, and to solve the latter problem. In this case, an oil passage switching valve that switches the oil passage to the next cylinder unit is installed directly on the cylinder unit, and the oil passage switching valve is configured to be directly switched by this cylinder unit at the extension end position of this cylinder unit. The gist of this is that the proximal boom, at least one intermediate boom, and the distal boom are slidably fitted in sequence in a lens-barrel type, and that the boom is extended and retracted between each adjacent boom. In a multistage telescopic boom each equipped with a cylinder device, the extension side oil chamber of each cylinder device is connected in series from the extension side oil chamber of the cylinder device on the base end side to the extension side oil chamber of the cylinder device on the tip side. In addition, an oil passage switching valve is provided in each oil passage that communicates the contraction side oil chambers of each cylinder device and connects each of the extension side oil chambers, and these oil passage switching valves configured to operate at the end of the extension operation of the cylinder device on the immediate proximal end side on the upstream side of the valve to open the oil passage,
Furthermore, a wedge is provided at the base end of each intermediate boom to lock each intermediate boom and the boom on the base end side adjacent to each intermediate boom, and prevent movement of each intermediate boom in the retraction direction. devices are provided, each wedge device being configured to unlock the distal boom by engaging the distal boom at the end of the retraction operation of the distal boom adjacent to each intermediate boom. It is a multi-stage telescopic boom.

The configuration of the present invention will be explained below.

First, a case of a three-stage boom, which is an embodiment of the present invention, will be described.

In FIG. 1, 1 is a proximal boom, 2 is an intermediate boom that is slidably fitted into the proximal boom 1, and 3
is a tip boom that is slidably fitted into the intermediate boom 2. 4 is a first cylinder device provided between the base end boom 1 and intermediate boom 2; 5 is a second cylinder device provided between intermediate boom 2 and tip boom 3; The intermediate boom 2 and the tip boom 3 are extended and contracted with respect to the intermediate boom 2. Reference numeral 6 denotes a wedge device for locking the proximal boom 1 and the intermediate boom 2 provided at the base of the intermediate boom 2, and is composed of a wedge 8 and a spring 9. 8 is biased toward the boom tip side by a spring 9 to be in a locked state. However, even in this locked state, if the intermediate boom 2 moves in the extension direction from the proximal boom 1, the wedge 8 will slide and move together with the intermediate boom, and no wedge action will be performed.
On the other hand, when the intermediate boom 2 moves in the retraction direction, the wedge 8 enters a so-called wedged state and is configured to be locked. This wedge 8 is provided with an engaging piece 8a, and at the end of the retracting operation of the tip boom 3, the base end 3a of the tip boom 3 engages with the engaging piece 8a, and the wedge 8 is attached to the spring 9.
The locking state is released by moving the locking device against the locking condition.

Next, the hydraulic circuit diagram for this three-stage boom is shown in the fourth section.
As shown in the figure. Extension side oil chamber 4a of first cylinder device 4
and the reduction side oil chamber 4b are connected to pipes 11 and 12, respectively.
It communicates with an oil supply/drainage device (not shown) via. Furthermore, the extension side oil chamber 4a of the first cylinder device 4 and the extension side oil chamber 5a of the second cylinder device 5 are connected to each other by the pipe 13, and the contraction side oil chamber 4b of the first cylinder device 4 and the contraction side oil chamber 4b of the second cylinder device 5 are connected. The side oil chambers 5b are communicated with each other through pipes 14, and an oil passage switching valve 7 is provided in the pipes 13.
As shown in FIGS. 4A and 4B, this oil passage switching valve 7 has a spool 15 in this switching valve that is always connected to a spring 20 in the contraction side oil chamber 4b of the first cylinder device 4.
At the end of the extension operation of the cylinder device, the spool 15 is pushed up against the spring 20 by the slope 18 and step 19 provided on the piston side of the piston rod 16, and the oil chamber is pushed up. 21 and 22 are configured to communicate with each other. 2
3 is a guide hole for pressure balance provided so that the spool 15 is not affected by the pressure oil in the contraction side oil chamber 4b. Note that 24 is a check valve provided in parallel with the oil passage switching valve 7, which prevents the flow from the extension side oil chamber 4a of the first cylinder device 4 to the extension side oil chamber 5a of the second cylinder device 5, and prevents the reverse flow. is configured to allow it.

Next, the operation of the three-stage boom configured as described above will be explained.

First, when pressure oil is supplied from the pipe line 11, the pressure oil is introduced into the extension side oil chamber 4a of the first cylinder device 4, and the cylinder device extends. As a result, the intermediate boom 2 and the distal end boom 3 extend with respect to the proximal boom 1. Immediately before the first cylinder device 4 finishes extending, the spool 15 of the switching valve 7 begins to be pushed by the slope 18 and is pushed up at the terminal end, causing the oil chamber 21 of the valve to be pushed upward.
and 22 are communicated. Therefore, the first cylinder device 4
Near the end of extension, the pressure oil acting on the extension side oil chamber 4a of the first cylinder device 4 further passes through the oil passage switching valve 7 and the pipe line 13 and reaches the extension side oil chamber 5a of the second cylinder device 5. The second cylinder device 5 will be extended. This causes the tip boom 3 to extend further than the intermediate boom 2 (FIG. 3). Note that when the tip boom 3 starts to extend, the base end 3a of the tip boom 3 separates from the engagement piece 8a of the wedge 8, and the wedge 8 moves to the right due to the reaction force of the spring 9, and the inside of the base boom 1 It is in close contact with the side view, creating a so-called wedge-locked state. That is, when the tip boom 3 is extended, the proximal boom 1 and the intermediate boom 2 are always in a wedge-locked state (locked in the retraction direction), and even when a load is applied to the boom, the intermediate boom 2 does not return to its original position ( intermediate boom retraction operation) will not occur.

Next, boom retraction will be explained. In the state shown in FIG. 3, when pressure oil is supplied to the pipe line 12, the pressure oil passes through the contraction side oil chamber 4b of the first cylinder device 4 and the contraction side oil chamber 5b of the second cylinder device 5.
As a result, both the first cylinder device 4 and the second cylinder device 5 can be contracted. However, the first
When a retraction force is applied to the cylinder device 4, the intermediate boom 2 tends to retract, but the direction of the retraction is the locking direction of the wedge device, so the intermediate boom 2 does not retract. Therefore, only the tip boom 3 that is locked to the second cylinder device 5 is preferentially retracted. The tip boom 3 retracts, and at the end of the retraction operation, the base end 3a of the tip boom 3 comes into contact with the engagement piece 8a of the wedge 8, pushing the wedge 8 back and separating the base boom 1 and the intermediate boom 2. is unlocked, and the intermediate boom 2 is therefore retracted (FIG. 2). Note that when the tip boom 3 is retracted, the oil in the oil chamber 5a of the second cylinder device 5 is discharged when the first cylinder device is in the extended state, so the valve position of the oil passage switching valve 7 is as shown in Figure 4B. Therefore, the oil will be discharged through the pipe line 13, the oil line switching valve 7, and the oil chamber 4a, but at the actual design stage, there may be manufacturing errors in the second cylinder device 5 and the switching valve 7. Considering the above, it is expected that the oil passage switching valve 7 will be in the valve position as shown in Fig. 4A before the second cylinder device is completely contracted, and the oil will not be drained. A check valve 4 that only allows flow in the oil drain direction is provided in parallel with the valve 7, and the circuit is configured such that the second cylinder device 5 can be retracted regardless of the valve state of the oil passage switching valve 7.

Next, FIG. 5 shows a configuration example of a boom extension/retraction device when the number of boom stages is five, and FIG. 6 shows a hydraulic circuit diagram in that case. In this case, since the number of intermediate booms is increased by two compared to the one in FIG. 1, the number of wedge devices 6, cylinder devices 4, and oil passage switching valves 7 at the base of the intermediate booms will be increased accordingly. The important point here is that during extension, each cylinder device and each oil passage switching valve 7 extend sequentially from the proximal boom to the intermediate boom and then to the tip boom. The connection from the extension-side oil chamber to the extension-side oil chamber of the next cylinder device on the tip end side must be connected in series via the oil passage switching valves 7, respectively. In addition, when the boom is retracted, it is retracted by the wedge device 6 and the boom on the tip side, and the oil chambers on the retraction side of each cylinder device need to be in a state where all cylinder devices can be compressed. , it is not necessarily necessary to connect them in series like the extension side oil chambers, but it is sufficient to connect them so that they can both be retracted (6th oil chamber).
(see figure).

Regarding the operation of this 5-stage boom, as in the case of the 3-stage boom mentioned above, when it is extended, the cylinder device 4 and oil passage switching valve 7 on the base end sequentially extend from the base end and contract. At a young age,
The cylinder device, the wedge device on the tip side, and the boom on the tip side will gradually reduce the size from the tip side.

As described above, in the present invention, when the number of boom stages is n, each of (n-2) wedge devices 6, cylinder devices 4, and oil passage switching valves 7 is required, and each device is arranged according to the above-mentioned embodiment. If provided, an n-stage telescopic boom according to the present invention will be obtained.

Next, the effects obtained by adopting the wedge device as the boom locking means of the present invention are as follows: (1) From the point at which the intermediate boom finishes extending, the intermediate boom locks at the proximal end at the same time as the distal end boom extends. It is wedge-locked to the side boom, but this locking is a surface locking, and no special dimensional accuracy in the length direction is required to ensure secure locking.

(2) This wedge locking device has a free step in the forward direction (when extended) and a locking structure in the backward direction (when retracted). Even if a pressure oil leak were to occur and the boom on the tip side extended, there would be a free step in the forward direction, and the intermediate boom would fully extend without damaging the wedge device. Furthermore, even if the tip boom is extended due to a leak of pressure oil from the oil passage switching valve while the intermediate boom is being extended, the intermediate boom will still be locked to the base boom when retracting, and the tip boom will be locked. Priority is given to reduction (effect of reversible locking structure). That is, when expanding and contracting, the oil passage switching valve 7 is always expanded and contracted sequentially regardless of the accuracy of the oil passage switching valve 7.

Further, in the present invention, the oil passage switching valve 7 is directly attached to the cylinder device 4, and the oil passage switching valve 7 is directly switched by the cylinder device at the extension end position of the cylinder device 4, so that the extension of the boom can be controlled. Compared to the conventional type that detects and switches, it is easier to install, and since it is not installed between the booms, problems such as the oil passage switching valve not operating due to bending or bending of the boom do not occur.

[Brief explanation of drawings]

1 to 3 are explanatory diagrams of embodiments of the present invention;
The figure is the same hydraulic circuit diagram, Figures 4A and 4B are explanatory diagrams of the main parts, Figure 5 is a configuration diagram in the case of a five-stage boom, which is an example embodiment of the present invention, and Figure 6 is the hydraulic pressure in the case of Figure 5. It is a circuit diagram. 1... Proximal boom, 2... Intermediate boom, 3...
Tip boom, 4... First cylinder device, 5... Second cylinder device, 6... Wedge device, 7... Oil passage switching valve.

Claims (1)

[Claims] 1 A multi-stage telescopic system in which a base end boom, at least one intermediate boom, and a distal end boom are slidably fitted into a lens barrel in sequence, and a cylinder device for extending and retracting the boom is provided between each adjacent boom. In the boom, the extension side oil chamber of each cylinder device is connected in series from the extension side oil chamber of the cylinder device on the base end side to the extension side oil chamber of the cylinder device on the tip side, and the retraction side oil chamber of each cylinder device is connected in series. An oil passage switching valve is provided in each oil passage that communicates the side oil chambers and connects each of the extension side oil chambers, and these oil passage switching valves are directly connected to each other on the upstream side of these oil passage switching valves. configured to operate at the end of the extension operation of the end cylinder device to open the oil passage,
Furthermore, a wedge is provided at the base end of each intermediate boom to lock each intermediate boom and the boom on the base end side adjacent to each intermediate boom, and prevent movement of each intermediate boom in the retraction direction. devices are each provided, and each wedge device is configured to unlock the distal boom by engaging the distal boom at the end of the retraction operation of the distal boom adjacent to each intermediate boom. A multi-stage telescopic boom.