JPH0754236Y2 - Crane overload prevention device - Google Patents

Description

[Detailed Description of the Invention] (Industrial field of application) The present invention is provided with a telescopic boom in which a plurality of booms are telescopically connected, and two booms adjacent to each other extend a predetermined length from each other. The present invention relates to an overload prevention device for preventing a load exceeding a limit lifting load value from being loaded and unloaded in a crane equipped with a boom lock device that locks both booms in such a state that the booms cannot slide.

(Prior Art) Conventionally, for example, in a truck crane or the like, in general, when the actual hoisting load value generated during crane work is equal to or higher than a critical value of crane overturning or a limit hoisting load value that is a limit of load supporting capacity, the crane is used. Equipped with an overload prevention device that disables work. The limit hoisting load value of the crane is stored in the controller in advance according to the boom length and boom hoisting angle.In this type of overload prevention device, the actual hoisting load value (generally, boom When the limit hoisting load value stored in advance has been reached by the strain gauge attached to the hoisting cylinder), various driving devices for crane work (for example, lifting winch, boom telescopic cylinder, boom hoisting cylinder, The operation of the turning device etc.) is stopped.

Further, in this type of telescopic boom type crane, in order to prevent a large load from being applied to the boom telescopic cylinder in the contracting direction when performing crane work with the telescopic boom extended, two adjacent booms are installed. There is one equipped with a boom lock device for locking each other in a non-slidable manner (for example, Japanese Utility Model Laid-Open No. 62-179288). This boom lock device is generally of a lock pin type, and by inserting a lock pin provided on the outer boom into a pin receiving hole provided on the inner boom between the two booms, the boom lock device can be freely inserted and removed. It is configured to lock both booms to each other. In the boom locked state with this boom lock device, the load in the boom contraction direction during crane work can be received by the lock pin, and the load lifting capacity can be improved compared to the telescopic boom that does not use the boom lock device. it can.

By the way, in the conventional overload preventing device for a crane with a boom lock device as described above, boom lock state detecting means for detecting the lock state of the boom lock device is provided, and the boom lock state is detected when the telescopic boom is extended. The crane work is controlled only when the boom lock state is detected by the detection unit (in other words, the crane work is disabled when the boom lock state detection unit does not detect the boom lock state). Further, the limit lifting load value stored in the controller is set on the basis of the operating state of the boom lock device. In the extended state of the telescopic boom, when the boom lock device is in the non-operating state, the load lifting capacity is lower than that in the operating state of the boom lock device. Has superior ability.

(Problems to be solved by the invention) However, in the above-described overload prevention device for the crane with the boom lock device, the crane work can be performed only when the boom lock device is in the operating state when the telescopic boom is in the extended state. Crane work is not possible when the lock device is not operating.) For example, even when lifting a low-load suspended load that allows sufficient crane work even when the boom lock device is not operating, Each time the telescopic boom is extended / retracted, the lock pin of the boom lock device has to be engaged / disengaged, which is troublesome. In addition, for example, when the boom lock device breaks down, the boom lock device cannot be released. If it is not possible to use, the telescopic boom itself has a load-lifting capacity, but it does not There was a problem that the operation could not be performed.

SUMMARY OF THE INVENTION The present invention has been made in view of the above problems of the overload prevention device in the crane with the boom lock device as described above, and in the operating state of the boom lock device, the crane work can be performed with a high load hoisting ability, and It is an object of the present invention to propose a crane overload prevention device that has a lower capacity than the boom lock device operating state even in the non-operating state, but can perform crane work without trouble.

(Means for Solving the Problem) The overload prevention device of the present invention forms a telescopic boom by connecting a plurality of stages of booms continuously by a telescopic drive device so that the booms can be extended and retracted one after another. In a crane equipped with a boom lock device that locks both booms in the boom length direction in a displaceable manner in a state where the booms extend a predetermined length relative to each other, a boom lock state detecting means for detecting a lock state of the boom lock device. And boom length detection means for detecting the length of the telescopic boom,
Boom angle detecting means for detecting the up-and-down angle of the telescopic boom, and each data emitted from the boom lock state detecting means, the boom length detecting means, and the boom angle detecting means may be calculated and added to the present telescopic boom. A limit lifting load value calculating means for calculating a limit lifting load value, an actual lifting load value detecting means for detecting an actual lifting load value applied to the telescopic boom during crane work, and the limit lifting load value calculation The limit hoisting load value calculated by the means and the actual hoisting load value detected by the actual hoisting load value are compared, and when the actual hoisting load value is smaller than the limit hoisting load value, the crane. Crane operation control means for enabling the operation and, conversely, disabling the crane operation when the actual hoisting load value is equal to or higher than the limit hoisting load value is provided.

(Operation) According to the overload prevention device of the present invention, the operation of the boom lock device is performed in consideration of the data from the boom lock condition detection device for detecting the lock condition of the boom lock device by the limit lifting load value calculation device. The critical lifting load value for each of the operating condition and the non-operating condition is calculated. In addition, the crane operation control means compares the limit hoisting load value calculated by the limit hoisting load value calculating means with the actual hoisting load value detected by the actual hoisting load value detecting means, and actually hoists Crane operation is possible while the load value is less than the limit hoisting load value, so even if the boom lock device is inactive, crane work is not possible if the actual hoisting load value is less than the limit hoisting load value. It will be possible.

(Effects of the Invention) Therefore, according to the crane overload prevention device of the present invention, the crane work can be performed in a state in which the load lifting capacity is large in the operating state of the boom lock device, and the boom lock device is provided in this manner. Even when the boom lock device is inactive, crane work can be performed, for example, when operating a crane with a load lower than the limit lifting load value when the boom lock device is inactive. Eliminates the troublesome work of engaging and disengaging the boom lock device each time the telescopic boom is extended and retracted.
Even if the boom lock device becomes inoperable due to a failure or the like, there is an effect that the crane work can be performed within the limit lifting load value in that state.

(Embodiment) An embodiment of the present invention will be described with reference to FIGS. 1 to 4. In this embodiment, a rough terrain crane is used as a crane.

The rough terrain crane shown is a swivel on top of the vehicle 1.
11 is provided, and three booms 21, 22,
A telescopic boom 2 of a two-stage telescopic type, in which 23 are sequentially connected in a telescopic manner, is mounted by a hoisting cylinder 12 so as to be hoistable.

Outriggers 19 (total 4
Equipped).

The base end part 21 of the telescopic boom 2 has a base part 11 having a swivel base 11.
The intermediate boom 22 is pivoted upward, and the intermediate boom 22 is made to extend and retract with respect to the base boom 21 by a first telescopic drive device (first telescopic cylinder) 3A, and the tip boom 23 is second telescopic drive with respect to the intermediate boom 22. The device (second telescopic cylinder) 3B is adapted to be telescopic.

The telescopic boom 2 is horizontally rotated together with the swivel base 11, the hoisting cylinder 12 is used to change the hoisting angle, and the telescopic cylinders 3A and 3B are telescopically moved.

Between the base boom 21 and the intermediate boom 22 and between the intermediate boom 22 and the distal boom 23, both booms (21 and 22, 22 and 2) are provided.
3) The booms (21, 22, 2
2 and 23) are provided with boom lock devices 4A and 4B for locking the boom length direction in a displaceable manner. The boom lock devices 4A and 4B have the same structure as each other, and basically, the tips of the base booms (21, 22) of the two booms (21 and 22, 22 and 23) are used. A lock pin 41 provided on the front side of the boom (22, 23) is removably fitted into a pin receiving hole 49 provided near the base end of the boom (22, 23) so that both booms can be locked to each other. Has been done. The boom lock device 4A on the base side provided between the base boom 21 and the intermediate boom 22 (the boom lock device 4B on the front side has the same structure) will be described in detail.
As shown in Fig. 3, 4A has one set of the same structure on each of the left and right sides of the boom. The lock pin 41 in each of the left and right boom lock devices 4A, 4A is installed slidably inward and outward in a boss 42 provided at the tip of the base boom 21. A piston 45 housed in a casing 43 and biased inward by a spring 44 is connected to the outer end of the lock pin 41. By supplying pressure oil into the hydraulic chamber 43a on the side opposite to the spring 44 of the casing 43, the piston 45 can be moved outward against the spring 44. On the other hand, near the base ends of the left and right side walls of the intermediate boom 22, pin receiving holes 49 (on the left and right side walls, respectively) are provided at positions corresponding to the lock pins 41 in a state where the intermediate boom 22 is fully extended with respect to the base end boom 21. There is one). And the boom lock device
The lock pins 41 are slid outward against the spring 44 by supplying pressure oil into the hydraulic chamber 43a (the lock pins are in the unlocked position) with respect to the proximal boom 21. The intermediate boom 22 can be expanded and contracted by the telescopic cylinder 3A, and when the pressure in the hydraulic chamber 43a is released with the intermediate boom 22 fully extended with respect to the proximal boom 21, the lock pin 41 pushes the spring 44. As a result, the tip of the lock pin 41 is fitted into the pin receiving hole 49 on the side of the intermediate boom 22.
In this lock pin inserted state, the base end boom 21 and the intermediate boom 22 are locked by the left and right lock pins 41, 41, and when a load is applied in the direction of contracting the intermediate boom 22 during crane work. Put that load on both lock pins
41, 41 will be able to support. A boom lock device on the front side provided between the intermediate boom 22 and the tip boom 23.
4B has the same structure as the boom lock device 4A on the base side, and the same operation can be obtained. In this way, the boom lock device 4
With the equipment equipped with A and 4B, during crane work, the boom lock device is not used (in the unlocked state) to support the load in the boom contraction direction with the telescopic cylinders 3A and 3B, and when the boom lock device is installed. There are two ways of using the lock pin 41 to support the load in the boom contraction direction in the locked state. In the locked state of the boom lock devices 4A and 4B, the load hoisting capability is improved and the limit hoisting load value is increased as compared with the case where the boom lock devices are not used. For example, when the telescopic boom 2 is in the most extended state as shown by the solid line in FIG. 1, each boom lock device 4A, 4B
When the boom lock devices 4A and 4B are locked, and when the boom lock devices 4A and 4B are unlocked, respectively, as shown in FIG. The upper limit of the limit lifting load value becomes high.
In the most extended state of the telescopic boom 2, one of the two boom lock devices 4A, 4B (for example, the boom lock device 4A on the base side) is always locked, and the other boom lock device (for example, the front side boom lock device 4A). Even when the limit lifting load values of the boom lock device 4B) in the locked state are compared with those in the unlocked state, the limit load in the locked state is higher than that in the unlocked state. Of course, the upper load value becomes high.

The boom lock device 4A on the base side and the boom lock device 4B on the front side are provided with boom lock state detecting means 5A, 5B for detecting the lock states of the boom lock devices 4A, 4B, respectively.
Is provided. This boom lock state detection means 5
In this embodiment, A and 5B are turned ON when the lock pin 41 is retracted inward until it is inserted into the pin receiving hole 49, and OFF when the lock pin 41 is pulled out from the pin receiving hole 49.
The operated switch 51 is adopted. The boom lock state detection means 5A, 5B may be provided on either the left or right boom lock device of the left and right base boom lock devices 4A, 4B and the left and right front boom lock devices 4A, 4B.

Further, in this crane, a boom length detecting means 6 for detecting an extension length of the telescopic boom 2, a boom angle detecting means 7 for detecting an inclination angle of the telescopic boom 2, and a second stage and thereafter. Each boom (2,23) is continuous to its base (2
Boom minimum contraction detecting means (15A, 15B) for detecting the maximum contraction with respect to 1, 22), the boom lock state detecting means (5A, 5B), the boom length detecting means 6, the boom angle detecting means. 7 and boom minimum reduction detection means (15A, 15B)
Limit lifting load value calculation means 8 for calculating the respective lifting data values that can be applied to the current telescopic boom 2 by calculating the respective data emitted from the above, and the actual lifting applied to the telescopic boom 2 when hoisting a suspended load. Actual lifting load value detecting means 9 for detecting the load value, limit lifting load value calculated by the limit lifting load value calculating means 8 and actual lifting load value detected by the actual lifting load value detecting means And a crane operation control means 10 for stopping various driving devices for crane work when the actual hoisting load value is equal to or higher than the limit hoisting load value.

As the boom length detecting means 6, the boom angle detecting means 7 and the actual hoisting load value detecting means 9, a boom length detector, a boom angle detector and a hoisting load value detector which have been generally used from the past are respectively adopted. Has been done. For example, as the boom length detecting means 6, a potentiometer 63 is attached to the rotary shaft of a drum 61 around which a wire 62 is wound, the drum 61 is attached to the side surface of the base boom 21, and the tip of the wire 62 is attached to the tip boom 23. It is fixed to the side and the voltage of the potentiometer 63 generated according to the rotation amount of the drum 61 that is rotated when the telescopic boom 2 is telescopic is output as boom length data. There is. or,
As the boom angle detecting means 7, a pendulum 72 is attached to the rotary shaft of the potentiometer 71, and the potentiometer 71 is fixed to the side surface of the proximal boom 21 so that the rotary shaft thereof is oriented horizontally. The rotary shaft of the potentiometer is rotationally driven by a pendulum 72 that rotates relative to the pendulum 72, and the voltage of the potentiometer 71 can be output as boom hoisting angle data. Further, as the actual hoisting load value detecting means 9, a means in which a strain gauge 91 is attached to the boom hoisting cylinder 12 and the resistance value of the strain gauge 91 can be output as data of the actual hoisting load value is adopted. There is.

Base side boom minimum contraction detection means 15A for detecting the maximum contraction state between the base boom 21 and the intermediate boom 22, and front side boom maximum contraction detection means 15B for detecting the maximum contraction state between the intermediate boom 22 and the tip boom 23. Have the same structure as each other, and the boom minimum contraction detection means 15A (or 15B) is a switch provided at the tip of the base boom 21 (or the intermediate boom 22).
16A (or 16B) and intermediate boom 22 (or tip boom 23) side, abutment member 17A for turning ON switch 16A (or 16B) when the intermediate boom (or tip boom) is reduced to the smallest size.
(Or 17B). In this type of telescopic boom, when the boom is in the most contracted state, the stoppers between the booms collide or the telescopic cylinders 3
Direct contact between the A and 3B cylinder tubes and pistons has the characteristic that the load lifting capacity allowed during crane work increases. If two continuous booms are extended even a little, the load applied in the boom contraction direction during crane work will be supported only by the telescopic cylinder (3A or 3B), and the load lifting capacity will decrease. The limit hoisting load value differs in terms of load bearing force between the boom fully contracted state and the boom extended state.

In FIG. 4, reference numeral A is a central processing unit. In the central processing unit A, a limit hoisting load value computing means 8 and a crane operation control means 10 are incorporated.

In this embodiment, the limit hoisting load value calculating means 8 is, as shown in FIG. 4, a boom length detecting means 6, a boom angle detecting means 7, boom lock state detecting means 5A, 5B and a boom minimum contracting detecting means 15A. 15B, the current limit lifting load value is calculated based on each data, and the limit lifting load values for many combinations of each data are stored in advance. Further, in this embodiment, the telescopic boom 2 is composed of three booms, and two boom lock devices are provided, and either the boom lock device 4A on the base side or the boom lock device 4B on the front side is provided. One of the boom lock devices may be used in a locked state. In that case, when the two boom lock devices 4A and 4B are both in the locked state, the limit lifting load value and both boom lock devices 4A and 4B are In each case, the limit lifting load value between the limit lifting load value in the unlocked state is stored. In this embodiment, the limit lifting load value is calculated by integrating the above four data, but in other embodiments, other factors that change the limit lifting load value (for example, the outrigger 19). The limit lifting load value may be calculated in consideration of the overhang length).

The crane operation control means 10 controls the crane's current limit lifting load value (calculated by the limit lifting load value calculating means 8) and the actual lifting load value (actual lifting load value detecting means 9) during crane operation. It is equipped with a comparison calculation function for comparing Then, the crane operation control means 10 compares and calculates the limit hoisting load value and the actual hoisting load value,
When the actual hoisting load value is less than the limit hoisting load value, crane operation is allowed (specifically, the main control valve of the hydraulic circuit for crane operation is turned on), and conversely the actual hoisting load value is the limit hoisting load value. When the load is equal to or higher than the upper load value, the operation of the crane is prohibited (specifically, the main control valve is turned off).

Then, in the overload prevention device of this embodiment, a part of the data for calculating the limit lifting load value, from the boom lock state detection means 5A, 5B for detecting the lock state of the boom lock device 4A, 4B. By incorporating the data, the limit hoisting load value calculating means 8 calculates the limit hoisting load value even when the boom lock devices 4A and 4B are in the unlocked state, and further, the limit hoisting load value calculating means 8 When the actual hoisting load value is smaller than the limit hoisting load value calculated in, the crane operation is allowed.For example, the actual hoisting load value is the limit when the boom lock device 4A, 4B is in the unlocked state. When operating the crane with a load smaller than the lifting load value,
The crane work can be performed without locking the boom lock devices 4A and 4B, and even if the boom lock device (4A or 4B) fails, the crane work can be performed in the unlocked state. Therefore, even a crane equipped with this type of boom lock device can be used in a wider range.

In addition, in this embodiment, the telescopic boom 2 is composed of three booms, but in other embodiments, the number of booms can be two or four or more. In that case, it goes without saying that the number of boom lock devices is also increased or decreased according to the number of booms.

[Brief description of drawings]

FIG. 1 is a side view of a crane equipped with an overload prevention device according to an embodiment of the present invention, and FIG. 2 is a partially enlarged view of FIG.
3 is a sectional view taken along the line III-III of FIG. 2, FIG. 4 is a block diagram of the overload prevention device of FIG. 1, and FIG. 5 is a state in which the boom lock device is locked in the overload prevention device of FIG. It is a change graph of the limit hoisting load value at the time of making it, and the case where it was made into an unlocking state, respectively. 2 ... Telescopic boom 3A, 3B ... Telescopic cylinder 4A, 4B ... Boom lock device 5A, 5B ... Boom lock state detection means 6 ... Boom length detection means 7 ... Boom angle detection means 8 ... Limit suspension Upper load value calculation means 9 …… Actual lifting load value detection means 10 …… Crane operation control means 21 …… Base boom 22 …… Intermediate boom 23 …… End boom 41 …… Lock pin 49 …… Pin receiving hole

Claims (1)

[Scope of utility model registration request] 1. A telescopic boom (2) is constructed by connecting a plurality of booms (21, 22, 23) continuously by a telescopic drive device (3A, 3B) so as to be mutually telescopic, and further adjacent to each other. A boom lock device that locks both booms (21 and 22, 22 and 23) in the boom length direction in a displaceable manner in a state where the two booms (21 and 22, 22 and 23) extend relative to each other by a predetermined length. 4A, 4B), a boom lock state detecting means (5A, 5B) for detecting the lock state of the boom lock device (4A, 4B), and a boom for detecting the length of the telescopic boom (2). A length detecting means (6), a boom angle detecting means (7) for detecting a hoisting angle of the telescopic boom (2), a boom lock state detecting means (5A, 5B),
Boom length detecting means (6), boom angle detecting means (7)
Limit lifting load value calculation means (8) for calculating each limit data to be added to the current telescopic boom (2) by calculating each data emitted from the telescopic boom (2), and the telescopic boom ( 2) The actual lifting load value detecting means (9) for detecting the actual lifting load value, the limiting lifting load value calculated by the limiting lifting load value calculating means (8), and the actual lifting load. The actual hoisting load value detected by the value detecting means (9) is compared, and when the actual hoisting load value is smaller than the limit hoisting load value, the crane operation is possible and conversely the actual hoisting load value is limited. A crane overload prevention device comprising: a crane operation control means (10) for disabling a crane operation when the load exceeds a hoisting load value.