JPH0431998B2 - - Google Patents

Description

Detailed Description of the Invention [Field of Industrial Application] The present invention relates to a mobile crane in which an upper rotating body equipped with a boom and a mast is rotatably mounted on a lower traveling body. This invention relates to a balance weight actuating device for a counterbalance crane, which is equipped with a balance weight suspended from the tip of the mast in addition to a main body weight attached to the rear of the crane.

[Conventional technology]

In a mobile crane consisting of an upper rotating body equipped with a boom and a mast mounted on the lower traveling body so as to be able to rotate freely, there is a balance suspended from the tip of the mast in addition to the main body weight attached to the rear of the upper rotating body. Counterbalance cranes equipped with weights are known. (For example, JP-A-62-
(See Publication No. 41192) In known counterbalance cranes of this type, the operator is responsible for determining whether or not to operate the counterbalance weight in addition to the main body weight, and for operating the counterbalance weight.

Therefore, the operator reads the load meter while operating the crane, recognizes the size of the load to be lifted, determines whether or not a balance weight is necessary, and if it is determined that it is necessary to use a balance weight, immediately A lifting operation had to be carried out.

On the other hand, in a mobile crane that does not have a main body weight but has a balance weight separate from the crane main body, the tension of the boom elevating rope and the boom inclination angle are detected, and the detected values are sent to a calculation device to stabilize the crane. It is also known that when the moment is calculated and the value exceeds a certain value, a hydraulic cylinder is operated to lift the balance weight from the ground. (Refer to Utility Model Publication No. 51-25177).

However, in order to detect the tension of the boom elevating rope and the inclination angle of the boom, it is necessary to install a measuring or detecting means at a high location on the crane, which not only makes maintenance inspection difficult but also In practice, it is extremely difficult to guide the measured values and detected values to the calculation device on the crane body.

In addition, since the lifting load is always applied to the boom elevation rope, the hydraulic cylinder continues to operate in the lifting direction even after the balance weight is lifted from the ground and the counterbalance is maintained.
Not only may the balance weight be lifted more than necessary, but once the balance weight has been lifted, even if the lifting load is reduced,
Since the balance weight is maintained in a lifted state, the overall balance is lost, making it difficult to perform stable operation, and it is not possible to respond to changes in the lifting load, making it difficult to apply to counterbalance cranes. There is a problem that.

[Problems to be solved by this invention]

In this way, according to the manual method, when operating a counterbalance crane, the operator is responsible for determining whether or not it is necessary to operate the balance weight, and for operating the balance weight. , when working with a crane, hoisting operation,
Raising and lowering the boom, and even the mast,
It is necessary to perform hoisting operations of the balance weights simultaneously or alternately in a well-timed manner, which requires skill and poses problems in terms of operability and safety.

Further, according to the method of hoisting a balance weight by detecting the tension of the boom elevation rope, there is a problem in that it is difficult to maintain a counterbalance in response to changes in the hoisting load.

The purpose of this invention is to solve the above-mentioned problems, to eliminate the problems caused by human judgment and operation, and to control the lifting and lowering of the balance weight in response to changes in the lifting load. This system detects the tension in the mast elevation rope that occurs when lifting a load, and automatically determines whether or not to operate the balance weight based on the detection signal.
This makes it possible to automatically lift, stop, and lower the balance weight in a timely manner in response to changes in the lifting load.

[Means for solving problems]

The present invention aims to provide a means for solving the above-mentioned problems, in which a boom 3 and a mast 4 are pivotably mounted on an upper revolving body 1 mounted on an undercarriage body 2 so as to be able to move up and down, In a counterbalance crane equipped with a main mast 8 connected to the tip of the mast 4 by a mast support pendant 20 and a mast elevation rope 17, and a balance weight 24 connected via a balance weight support pendant 26 and a hydraulic lifting device 25. , A means 30 for detecting the tension of the mast elevation rope 17 is provided between the mast elevation rope 17 and the main mast 18, and when the tension of the mast elevation rope 17 detected by the detection means 30 is below a predetermined lower limit value. The hydraulic lifting device 25 is operated in the extension direction, when the value exceeds a predetermined upper limit, it is operated in the contraction direction, and when the value is between the two, it is stopped, and the lifting and lowering of the balance weight is controlled in immediate response to changes in the lifting load. This made it possible.

〔Example〕

The structure of the present invention will be explained with reference to embodiments shown in the drawings.

FIG. 1 shows an outline of a counterbalance crane to which the present invention is applied.

In the figure, reference numeral 1 denotes an upper revolving body which is rotatably mounted on a lower traveling body 2.

A boom 3 and a mast 4 are pivotally attached to the front part of the upper revolving structure 1 so that they can be raised and raised freely, and a hoisting winch 5, a mast elevation rope 6, and a boom elevation winch 7 are provided. 8 is installed. Further, a main body weight 9 is attached to the rear thereof.

Hoisting rope 1 let out from hoisting winch 5
0 is hooked around the sheave of the hook block 12 via sheaves 11 and 11' attached to the tip of the boom 3, and is connected to the tip of the boom 3.

The mast elevating rope 17 let out from the mast elevating winch 6 is connected to a mast bail 18 pivotally connected to the main mast 8 and a mast bridle attached to the lower end of a mast support pendant 20 whose upper end is attached to the tip of the mast 4. 19 and then connected to an elevation rope tension detection device 30 attached to the main body mast 8.

As shown in FIGS. 3 to 6, this elevating rope tension detection device 30 is composed of an outer cylinder 30a, a spring 30b, a rod 30c, a lug 30d, spring retainers 30e and 30f, limit switches 31a and 31b, etc. There is.

One end of the outer cylinder 30a is pivotally connected to the main mast 8 by a pin 34, and a rod 30c whose one end is connected to the mast elevation rope 17 via a socket 32 and a pin 33 is inserted into the inner side of the outer cylinder 30a. A spring 30b is installed between the rod 30c and the inner wall of the outer cylinder 30a.

Spring retainers 30e and 30f are attached to the other ends of the rod 30c and the outer cylinder 30a, respectively, and a nut 30g and a bolt 30h are respectively attached.
It is fixed by.

A lug 30d is fixed to the spring holder 30e at the tip of the rod 30c, and the spring holder 30e compresses the spring 30b due to the tension of the mast elevation rope 17, and the lug 30d responds to the deflection of the spring 30b to cause the rope tension detection device 30 to
A notch (slit) is provided in the longitudinal direction of the outer cylinder 30a so that the outer cylinder 30a can be moved in the direction of the load.

31a and 31b are limit switches operated by the lug 30d, which are operated by the elevating rope 17.
When the detected value of the rope tension detection device 30, which is a means for detecting the tension of
31a is configured to operate when the value exceeds a predetermined upper limit value.

Then, as shown in the diagram, lower limit switch 3
When the upper limit switch 1b is activated, the hydraulic elevating device 25 for lifting a balance weight, which will be described later, is expanded and contracted in the extension direction, and when the upper limit switch 31a is activated, it is expanded and contracted in the contraction direction.

The boom elevating rope 13 let out from the mast elevating winch 7 is attached to a boom bail 14 pivotally attached to the tip of the mast 4 and a boom bridle attached to the other end of a mast elevating pendant 16 whose one end is attached to the boom tip. 15 and then connected to the boom bail 14.

A balance weight truck 22 equipped with tire-type wheels 23 as shown in FIG. The truck 22 and the rear end of the revolving upper structure 1 are connected by a pin via a connecting stay 21 so that the truck 22 can move up and down.

An upper end of a balance weight support pendant 26 is connected to the tip of the mast 4, and a link 27 is connected to the lower end of the balance weight support pendant 26.
and 28, the tip of the piston rod side of the lifting cylinder constituting the hydraulic lifting device 25 for lifting the balance weight is connected, and the bottom side of the lifting cylinder is connected to the link 29 attached to the balance weight cart 22. There is.

[Effect]

The operation of the present invention will be explained with reference to the above embodiments.

When a load is suspended, the mast support pendant 20 and the mast elevation rope 17 are connected to the mast support pendant 20 via a mast bridle 19.
A tensile force acts on the rope, and the spring 30b of the rope tension detection device 30 is bent in proportion to the magnitude of this tension.
Lug 30d fixed to spring retainer 30e
moves in the load direction, and the limit switches 31a,
31b, and also operates a solenoid valve (not shown) based on its output signal to extend and retract the lifting cylinder of the balance weight hydraulic lifting device 25.

That is, when no load is suspended, no tension is generated in the mast elevation rope 17, so the spring 30b of the rope tension detection device 30 does not bend.
The lug 30d keeps the lower limit switch 31b in an activated state, and the pressure oil from the hydraulic pump (not shown) acts in the direction of extending the lifting cylinder of the hydraulic lifting device 25, and the tire of the balance weight truck 22 The type wheel 23 remains in contact with the ground, and no tension is generated in the balance weight support pendant 26, but rather it becomes loose and the power of the balance weight 24 does not act on the mast 4 at all.

Next, when a load is suspended, tension is generated in the mast elevation rope 17, but when the tension is below a predetermined lower limit, that is, while the lifting load is small, the spring 30b hardly bends and the lower limit switch 31b is activated. Keep it in working condition.

Therefore, in the case of no load or a small load, the gravity of the balance weight 24 is not inadvertently applied to the mast 4, thereby preventing the inconvenience of causing the aircraft to become unbalanced.

When the suspended load exceeds a certain constant load, the spring 30b begins to bend and the lower limit switch 3
1b is deactivated, the supply of pressure oil to the hydraulic lifting device 25 is cut off, and the lifting device 25 is stopped and fixed in that state. However, the wheels 23 of the balance weight truck 22 remain in contact with the ground.

Therefore, in this state, the weight of the balance weight 24 is not acting on the mast 4 yet, but if the load of the suspended load increases and a situation occurs where the weight of the main body weight 9 alone is insufficient, the balance weight 24 is immediately applied. This means that the gravity of

Furthermore, as the lifting load increases, the tension of the mast elevation rope 17 also increases, so the spring 30
When the amount of deflection of b increases and the tension of the rope 17 exceeds a predetermined upper limit value, the upper limit switch 3
1a is activated. Then, the pressure oil moves to the hydraulic lifting device 2.
The balance weight truck 22 is lifted up via the link 29, and the wheels 23 are grounded.

As a result of the ground cutting, when the weight of the balance weight 24 acts on the tip of the mast 4, the weight acts in a direction that balances the weight of the suspended load, and the tension of the mast elevation rope 17 decreases by the corresponding amount, from the upper limit value. Return to intermediate value. Therefore, spring 30
The amount of deflection of the lug 30d also decreases slightly, and the lug 30d moves away from the upper limit switch 31a, taking an intermediate position between the upper and lower limit switches 31a and 31b. Then,
The supply of pressure oil to the hydraulic lifting device 25 is cut off,
Since the lifting device 25 is stopped and fixed at that position, stable operation is possible without lifting the balance weight 24 more than necessary.

In this way, when the lifting load increases and the tension of the mast elevation rope 17 exceeds a predetermined upper limit, the hydraulic lifting device 25 automatically operates in the contraction direction, lifting the balance weight 24 and applying the weight. The stability moment can be increased.

When the load and the weight of the balance weight 24 are balanced and the counterbalance is maintained,
Since the hydraulic lifting device 25 is stopped and fixed at that position, the balance weight 24 is not lifted more than necessary.

In addition, the lifting load is reduced and the mast elevation rope 1
When the tension of the balance weight 7 becomes less than a predetermined lower limit value, the hydraulic lifting device 25 operates in the extension direction, and the balance weight 2
4 can be lowered and the wheels 23 of the truck 22 can be brought into contact with the ground, so stable operation can always be performed under a stable moment in response to changes in load.

〔effect〕

According to the present invention, the means 30 for detecting the tension of the mast elevation rope 17 is provided between the mast elevation rope 17 and the main mast 18, and the tension of the mast elevation rope 17 detected by the detection means 30 is set to a predetermined value. When operating the counterbalance crane, the hydraulic lifting device 25 is operated in the extension direction when the lower limit is below, and in the contraction direction when it is above the predetermined upper limit, and stopped when the value is between the two. , the necessity and operation of the balance weight can be determined without relying on human judgment and operation, by detecting the tension in the elevating rope that occurs when lifting a load, and automatically determining the necessity of the balance weight operation based on the detection signal. It is possible to automatically lift, stop, and lower the balance weight in response to changes in the lifting load, reducing operator fatigue and greatly improving work safety and operability. There are effects that can be improved.

Further, since the means 30 for detecting the tension of the mast elevation rope 17 only needs to detect predetermined upper and lower limit values set in advance, a simple lit switch is sufficient. Since the ground clearance is relatively low, maintenance and inspection are easy.

[Brief explanation of drawings]

Fig. 1 is an overall side view of the counterbalance crane of the present invention, Fig. 2 is a rear view of the balance weight portion, Fig. 3 is a side view showing the tension detection means of the elevating rope, Fig. 4 is a plan view thereof, and Fig. 4 is a plan view thereof. FIG. 5 is an enlarged side sectional view of the tension detection means for the elevating rope, and FIG. 6 is a plan view thereof. 1... Upper revolving body, 4... Mast, 6... Mast elevation winch, 8... Main mast, 17... Mast elevation rope, 24... Balance weight, 25... Balance weight hydraulic lifting device, 26... Balance weight support pendant, 30... Elevation Rope tension detection device, 30a...outer cylinder, 30b...spring, 30c
... Rod, 31... Limit switch, 31a... Upper limit switch, 31b... Lower limit switch.

Claims (1)

[Claims] 1 Upper revolving structure 1 mounted on lower traveling structure 2
A boom 3 and a mast 4 are pivotably mounted on the
The tip of the mast 4 and the mast support pendant 20
And, in a counterbalance crane equipped with a main mast 8 connected by a mast elevating rope 17 and a balance weight 24 connected via a balance weight support pendant 26 and a hydraulic lifting device 25, the mast elevating rope 17 and the main mast 18 are A means 30 for detecting the tension of the mast elevation rope 17 is provided between the two, and the detecting means 30
When the tension of the mast elevation rope 17 detected is below a predetermined lower limit, the hydraulic lifting device 25 is operated in the extension direction, when it is above the predetermined upper limit, it is operated in the contraction direction, and when the tension is between the two, it is stopped. A balance weight actuating device for a counterbalance crane, characterized in that the balance weight actuating device is configured to