JPH0986878A - Weight detection device of counter weight in truck crane - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable to clearly detect whether a weight is loaded newly or not when an additional weight is light. SOLUTION: When the weights 35 with the number exceeded a prescribed number are supported on a support device 4, the gravity center G of entire counter weight 3 is displaced to the more rear side of a turning stand 2 than the support fulcrum P of the support device 4 and the front side of the counter weight 3 supported by the support device 4 can be turned upward by some amount around the support fulcrum P by the off-centered weight of the counter weight 3. In the more front side of the turning stand 2 than the support fulcrum P of the support device 4, one part of the counter weight 3 is collided with the proper place of the turning stand 2 from a lower side and the detection value detected by a weight detector 5 is made larger than the amount of an actual exceeded weight by the reaction force generated on the collided part.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a counterweight weight detecting device for a mobile crane.

[0002]

2. Description of the Related Art When a crane vehicle is used for crane work, particularly when a heavy load is to be hung, the weight of the suspended load is adjusted at the rear end of the swivel base to prevent the crane vehicle from falling. Attach the counterweight with the appropriate weight. Figure 6
In the prior art example, a total of five weights 31 to 35, that is, the first to fifth weights, are used as the counter weights 3. The weight of each weight shown in FIG. 6 is, for example, 10 tons for each of the first, second and fourth weights 31, 32 and 34,
The third weight 33 is 14 tons and the fifth weight 35 is 6 tons. Then, in this type of mobile crane 1, before performing the crane work, the weights 31 to 35 are appropriately combined and a counterweight 3 having a weight corresponding to the suspension load amount is attached to the rear end portion 21 of the swivel base 2. deep.

Further, in the conventional weight detecting device for counterweight shown in FIG. 6, the counterweight 3 is supported by a supporting device 4 using a hydraulic cylinder 41.
A pair of hydraulic cylinders 41 is provided on each of the left and right side surfaces of the swivel rear end portion 21. A weight detector (load cell) 5 is built in the hydraulic cylinder 41, and the weight detector 5 can detect the total weight of the counterweight 3. The weight detector 5 is usually provided only on the hydraulic cylinder 41 on one side, and therefore the weight of the counterweight 3 detected by the weight detector 5 is half the actual weight. Counterweight 3 detected by the weight detector 5
Is displayed on the display screen 12 in the cab 11,
The operator can see it and recognize how much weight the counterweight 3 is currently mounted on.

[0004]

By the way, the weight detector (load cell) 5 used in the weight detecting device of this type of counterweight is not very accurate, and the temperature detector and the counterweight are shocked. When is added, the output value (resistance value) changes. In particular, when the total weight of the current counterweight is large and the weight to be added to it is light, the ratio of the increased weight to the total weight is small, and even if the weight is added, it is used as a weight detector. In some cases, it could not be clearly detected in 5. For example, in the conventional example of FIG. 6, when the support device 4 supports the first to fourth weights 31 to 34, the total weight thereof is 44 tons, and the weight is relatively light (for example, 6 tons). The weight increase rate when the fifth weight 35 of) is added is relatively small at about 13.6%. Therefore, in the conventional counterweight weight detecting device, when the additional weight is lightweight, it may not be possible to clearly detect (display on the display screen 12) whether or not a new weight is placed, and the operator may make a mistake. There was a risk of making a decision. In addition, in this type of crane vehicle 1, the allowable overturning moment amount changes depending on the total weight of the counterweight 3 attached to the rear end portion 21 of the swivel base, but the weight of the counterweight is adjusted without adding the additional weight. When it is set (when the performance switching operation is not performed), the overturn prevention device operates before there is actually a surplus in the allowable overturning moment amount, and work with a higher load (overturning moment increasing side work) Cannot be done.

In view of the above-mentioned circumstances, the present invention is a weight detecting device for a counter weight, which is capable of clearly detecting whether or not the weight is newly mounted even if the weight newly added is lightweight. It is intended to provide.

[0006]

The present invention has the following structure as means for solving the above-mentioned problems.

That is, according to the present invention, a counter device composed of an appropriate number of weights is supported by a support device attached to the rear end of a swivel base of a crane vehicle, and each weight is provided by a weight detector provided on the support device. In a weight detecting device for a counterweight in a mobile crane that is capable of detecting the total weight of the weights, when the supporting device supports a number of weights exceeding a predetermined number, the center of gravity of the total weight of the weights is the supporting device. Of the counterweight, and the front side of the counterweight supported by the supporting device can rotate upward by a slight amount about the support fulcrum due to the eccentric weight of the counterweight. At the same time, on the front side of the swivel base with respect to the support fulcrum of the supporting device, a part of the counterweight collides with a proper position of the swivel base from below. It is characterized in that there was Unishi.

A hydraulic cylinder can be adopted as the supporting device, and a pair of hydraulic cylinders may be provided on both left and right side surfaces of the rear end of the swivel base. As the weight detector, for example, a load cell incorporated in a hydraulic cylinder can be adopted.

The counterweight supported by the supporting device is configured so that it can be rotated by a slight amount within a vertical plane that faces the front-rear direction of the swivel about the supporting fulcrum of the supporting device. Further, when a total of five weights are used as counterweights corresponding to the suspended load amount, the weights (four) of the first to fourth weights are supported by the support device. The center of gravity of the total weight should be located on the vertical line (or front side) of the supporting fulcrum of the supporting device in a side view. At that time, a part of the four weights is abutted (or close to the swivel base from below) at an appropriate position on the swivel base in front of the support fulcrum. Then, a fifth weight to be added to these weights is placed at a position eccentric to the rear side of the support fulcrum, whereby the center of gravity of the entire counterweight is displaced to the rear side of the support fulcrum. . When the center of gravity of the entire counterweight is displaced rearward from the support fulcrum in this manner, the eccentric weight causes an action of rotating the entire counterweight about the support fulcrum, and the pivoting action causes the impact to occur. At the joint, a part of the weight is pressed into contact with the swivel base from below. If a part of the weight is pressed against the swivel base from below under the support fulcrum, a reaction force equivalent to the pressure contact force is applied downward to the weight side of the pressure contact portion, but the magnitude of the reaction force is as described above. It becomes smaller as the horizontal distance from the support fulcrum to the abutting portion becomes longer. Therefore, in order to increase the reaction force, it is preferable to bring the abutting portion in the horizontal direction as close as possible to the support fulcrum.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION An embodiment of the present invention will be described with reference to FIGS. 1 to 5, and a counterweight weight detecting device of this embodiment is, for example, a crane truck 1 as shown in a conventional example of FIG. Can be adopted to. In the mobile crane 1 shown in FIG. 6, a swivel base 2 is installed on a carrier frame 8, and a telescopic boom 9 and each winch device 1 are mounted on the swivel base 2.
0, 10 and cab 11 are installed. The rear end 21 of the swivel base 2 projects a considerable distance in the radial direction from the swivel center. Further, there is a considerable gap between the lower surface of the swivel rear end portion 21 and the upper surface of the carrier frame 8.

As shown in FIGS. 1 and 2, the counterweight weight detecting device of the present embodiment has a support device 4 for supporting the counterweight 3 and a total weight of the counterweight 3 supported by the support device 4. It has a weight detector 5 for detecting.

In this embodiment, as the counter weight 3, a total of five weights 31 to 35, that is, first to fifth weights, can be appropriately combined and used. The weights of the weights used in this embodiment are as follows: from the bottom, the first weight 31 is 10 tons, the second weight 32 is 10 tons, the third weight 33 is 14 tons, and the fourth weight 34 is 10 tons. The fifth weight 35 is 6 tons.

The first weight 31 is provided with two vertically long connecting rods 31a, 31a extending upward on each of the left and right surfaces.

The second weight 32 has the same area as that of the first weight 31, and each connecting rod 31a, 31 of the first weight 31.
It is placed on the first weight 31 in a state of being housed between a. In addition, each connecting rod 3 in the second weight simple substance 32
A vertical groove into which the connecting rod is fitted is formed at a position corresponding to 1a, 31a.

The third weight 33 has a lower half portion 33a having the same area as that of the second weight 32 and an upper half portion 33b formed by partially projecting rearward from a rear end portion of the lower half portion. There is. A lower half portion 33a and an upper half portion 33b of the third weight 33 have a step, and an arc groove 33c for guiding a float 47 of the support device 4 described later is formed on the upper surface of the lower half portion 33a. There is. Locking grooves 33d and 33d (two positions) for locking the float 47 are provided in the circular arc groove 33c.
Are formed. In addition, the third weight 33 is the first
The tip ends of the connecting rods 31a of the weight 31 are pin-connected (total of 4 points) to be connected.

The fourth weight 34 is formed in a slightly smaller area than the upper half portion 33b of the third weight 33. The fourth weight 34 is pin-joined to the third weight 33 at a total of two locations, one on the left and one on the right, while being placed on the upper half portion 33b of the third weight 33.

The fifth weight 35 has the same area as the fourth weight 34, and is pinned to the fourth weight 34 at a total of two positions, one on the left and one on the right, in a state of being placed on the fourth weight 34.

Incidentally, the first weight 31 and the second weight 32.
And the lower half portion 33a of the third weight 33 is the rear end portion 2 of the swivel base.
1 is located on the lower surface side, and the upper half 3 of the third weight 33 is
The 3b, the fourth weight 34, and the fifth weight 35 are located behind the swivel base rear end portion 21.

As the supporting device 4, a hydraulic cylinder 41 is used. The hydraulic cylinders 41 are provided one on each of the left and right side surfaces of the rear end portion 21 of the swivel base 2, and support the counterweight 3 at two points. still,
Each of the hydraulic cylinders 41, 41 has a mounting base 40.
Is attached to each side of the swivel base 2.

The cylinder rod 42 of each of the hydraulic cylinders 41, 41 penetrates the cylinder tube vertically.
At the upper end of the cylinder rod 42, a swing link 4 that swings in a horizontal plane via a bend / extend link 44 that can bend and extend vertically.
5 are attached. The swing link 45 can be swung by the swing cylinder 43 within an angle range of 90 °. When the hydraulic cylinder 41 is expanded / contracted, the bending / expanding link 44 flexes / expands to allow the vertical movement of the cylinder rod 42. On the other hand, when the rotating cylinder 43 is expanded / contracted, the cylinder rod 42 is angled via the swinging link 45. It can be rotated in the range of 90 °. A float 47 that locks the third weight 33 is attached to the lower end of the cylinder rod 42 by a connecting pin 48. The float 47 has a long side portion that can be locked in the locking groove 33d of the third weight 33 from below, and a short side portion that can be inserted into the circular arc groove 33c of the third weight 33. Further, the float 47 can swing up and down by a slight amount about the connecting pin 48. In addition, a lock pin 46 that prohibits the rotation of the cylinder rod 42 and bears the weight of the counterweight 3 is inserted into the upper exposed portion of the cylinder rod 42 so as to be freely inserted and removed. The lock pin 46 is a float 47.
Is inserted into the hole of the cylinder rod 42 with the long side of the float 47 being fitted in the locking groove 33d and the float 47 being lifted to a predetermined height. Further, the lock pin 46, while being inserted into the cylinder rod 42, is fitted into the U-shaped groove of the support provided on the upper part of the mounting base 40 to inhibit the horizontal rotation of the cylinder rod 42 and to counterweight the counterweight. When a sudden shock is applied to 3, the U of the support
The weight of the counterweight 3 can be supported by abutting against the bottom of the groove (the hydraulic cylinder 41 is not unduly loaded).

The weight detector 5 uses a hydraulic cylinder 41 of the supporting device 4 in which a load cell is incorporated. It should be noted that the weight detector 5 is provided with one hydraulic cylinder 41.
Used only for. Then, the weight detector 5 detects the load applied to the hydraulic cylinder 41 and sends the detection signal (electrical signal) to the controller in the operator's cab 11, where it is processed and displayed on the display screen 12. The weight detector (load cell) 5 of this type does not detect the load applied to the hydraulic cylinder 41 very accurately because its resistance value changes due to temperature and shock during work.

The counterweight 3 is attached to the supporting device 4 as follows. First, an appropriate number of weights including at least the third weight 33 are assembled on the carrier frame 8 on the front side of the turning center at a position separated by the distance from the turning center of the turning table 2 to the float 47. . At this time, the circular arc groove 33c of the third weight 33
However, it should be positioned just below the float 47 that is being turned. Next, the hydraulic cylinders 41, 41 are expanded and contracted so that the floats 47, 47 are located at a height where they can be inserted into the circular arc groove 33c of the third weight 33, and the rotary cylinders 43, 43 are operated. The float 47 has a posture in which the long side portions of the floats 47 and 47 can be parallel to the circular arc groove 33c. Then, the rear end portion 21 of the swivel base 2 is swung to the position above the third weight 33 to insert the floats 47, 47 into the circular arc groove 33c, and the floats 47, 47 with the locking grooves 33d, 33.
Corresponds to d. Subsequently, the rotary cylinders 43, 43 are operated to fit the long side portions of the floats 47, 47 into the locking grooves 33d, and then the hydraulic cylinders 41, 41 are inserted.
When the floats 47, 47 are moved upward by operating, the weights connected to the third weight 33 can be simultaneously lifted. Further, in this manner, with the float 47 being lifted to the predetermined height, the lock pin 46 is inserted into the hole provided in the cylinder rod 42 and locked. In this state, the lock pin 46 causes the cylinder rod 42 to
Rotation is prohibited. Further, the lock pin 46 abuts on the support above the mount 40 when the counterweight 3 is suddenly shocked,
The weight of the counterweight 3 can be carried. In this state, the swivel base 2 can freely swivel.

Incidentally, the fourth weight 34 and the fifth weight 35.
May be assembled in advance on the third weight 33 on the carrier frame 8. In that case, the stacking work of the respective weights can be carried out by lifting with a own crane. Further, the fourth weight 34 and the fifth weight 35 may be stacked on the third weight 33 by another crane if necessary.

First to fourth weights 31 to 31 in total
When the weights of the weights 31 to 34 are supported by the support device 4 in the assembled state, the center of gravity G ₁ of the total weight of the weights 31 to 34 is a support fulcrum P of the support device 4 in a side view as shown in FIG. Vertical line Q (position of connecting pin 48)
It is located on the top (or front side). Then, as shown by the chain line in FIG.
When placed on the weight 34, the center of gravity G of the total weight of the first to fifth weights 31 to 35 is displaced rearward from the vertical line Q of the support fulcrum P of the support device 4 in a side view. It has become.

By the way, in this weight detecting device for the counterweight, when the first to fourth weights 31 to 34 are lifted up to a predetermined height by the supporting device 4, the swivel base 2 is moved from the supporting fulcrum P of the supporting device 4. On the front side, a part of the upper surface of the lower half portion 33a of the third weight 33 is set to approach (or abut) a part of the lower surface of the swivel base 2 in a substantially contact state. In this embodiment, the support fulcrum P of the support device 4 is
At a position relatively closer to the front side of the swivel base, the swivel base 2
While the receiving members 61 are attached to the lower end portions of the left and right side surfaces, respectively, an abutment pin 62 having an appropriately small height that can abut the respective receiving members 61 on the upper surface of the lower half portion 33a of the third weight 33.
Projected (in two places on the left and right). Each receiving member 6
1 uses a bolt whose height can be finely adjusted. Then, when the third weight 33 is lifted to a predetermined height, the two left and right abutment pins 62 on the third weight 33 side are in close contact (or abutment) with the respective receiving members 61 on the swivel base 2 side. I am trying to do it. As described above, when the receiving member 61 and the abutting pin 62 are provided, the third weight 3
A gap can be formed between the upper surface of the lower half portion 33a of the No. 3 and the lower surface of the swivel base 2, and the third weight 33 does not directly abut the swivel base 2.

The abutting portion formed by the abutting pin 62 and the receiving member 61 is a reaction force downward toward the abutting pin 62 due to the counterweight rotating action when the fifth weight 35 is added as described later. F (FIG. 3) is generated, and the magnitude of the reaction force F increases as the horizontal distance L ₂ from the support fulcrum P to the abutting portion (receiving member 61, abutting pin 62) increases. Get smaller. Therefore, in order to secure the reaction force F of a predetermined magnitude or more, the abutting portion (61,
It is preferable that (62) be as close to the supporting fulcrum P as possible in the horizontal direction (distance L ₂ ).

In the weight detecting device for the counter weight, when the weights 31 to 34 of the first to fourth weights are supported by the supporting device 4, as shown in FIG. 3, the total weight W ₁ of the weights is calculated. The center of gravity G ₁ is on the vertical line Q of the supporting fulcrum P of the supporting device 4 in the side view (the same height in the example of FIG. 3).
Therefore, the abutting pin 62 on the third weight 33 side does not come into pressure contact with the receiving member 61 on the swivel base 2 side. However,
When the fifth weight 35 is placed on the fourth weight 34,
The center of gravity G of the total weight W of the counterweight 3 is deviated to the rear side by a horizontal distance L ₁ from the vertical line Q of the support fulcrum P in a side view, and the eccentric weight W ₂ centers the entire support weight P on the support fulcrum P. Then, the action of rotating in the clockwise direction occurs. Then, the abutment pin 62 on the third weight 33 side
Is strongly abutted against the receiving member 61 on the swivel base 2 side, and a downward reaction force F acts on the abutting pin 62 at that time.
The magnitude of the reaction force F at this time is determined by the eccentric weight W _{2 of the} counterweight 3 × the center G of the counterweight 3 in FIG.
The horizontal distance L ₂ to the abutment portion from the horizontal distance L ₁ ÷ supporting fulcrum P to the supporting fulcrum P from. Therefore, if the weight of the added fifth weight 35 is constant, the eccentric weight W ₂
And the horizontal distance L ₁ (rotational moment) is determined, and in order to increase the reaction force F, the horizontal distance L ₂ from the support fulcrum P to the abutting portion may be shortened. In this embodiment,
The horizontal distance L ₂ is about 300 to 400 mm.

Then, the reaction force F acts to push down the support fulcrum P of the support device 4, and as a result, a load larger than the actual weight of the fifth weight 35 is applied to the hydraulic cylinder 41. . As a result, the weight detector 5 built in the hydraulic cylinder 41 detects a load larger than the actual increased weight. For example, as shown in FIG. 5, the total weight W of the first to fourth weights 31 to 34 is W.
_In the state where ₁ is supported, the weight detector 5 outputs the detection resistance value M ₀ as it is. Next, when the fifth weight 35 is added, in the normal case (when there is no reaction force F), the detection resistance value M ₁ including the additional weight is output, but if a temperature change or a shock occurs, the weight detector is detected. When the detection accuracy of No. 5 is deteriorated, a detection resistance value considerably lower than M ₁ may be output despite the addition of the fifth weight 35. By the way, in this embodiment, when the fifth weight 35 is added, the reaction force F is generated, and the weight detector 5 receives the first to fifth weights.
The total load of the total weight W of the weights 31 to 35 and the reaction force F is applied, and the weight detector 5 outputs the detection resistance value of M ₂ . In this case, than the normal by M ₂ -M ₁ outputs a large detection resistance value.

Therefore, even if the weight of the added fifth weight 35 is relatively light (for example, about 6 tons), a load significantly larger than the weight is applied to the hydraulic cylinder 41 (the resistance value of the weight detector 5 is large. Therefore, it is possible to clearly know whether or not the fifth weight 35 is newly added. In this case, the resistance value output from the weight detector 5 does not correspond exactly to the actual weight of the counter weight 3, but the fifth weight 35 to be added is added.
The weight of is known to the operator in advance, and the operator only needs to be able to confirm whether or not the weight to be added is newly placed. If it can be confirmed that the added fifth weight 35 is placed, the performance is switched to a value corresponding to the weight of the counterweight 3 (the moment limit is increased),
Perform crane work.

In the counterweight 3 of the present embodiment,
In addition to the above respective configurations, the following configurations are provided.

As shown in FIG. 1, a small upward protruding piece 32a is attached to the rear end of the upper surface of the second weight 32. This small protruding piece 32a is used for each weight 3 of the third weight or higher.
It is located rearward of the center of gravity of the total weight of 3, 34 and 35. The small protruding piece 32a has the following function. That is, the third
In the weight 33, the upper half portion 33b is largely projected rearward, and moreover, the fourth weight 34 and the fifth weight 35 are placed on the upper half portion 33b of the third weight 33,
The center of gravity of the total weight of the third weight 33 or more is closer to the rear side than the position of the arc groove 33c of the third weight 33.
If the connection rod 31a on the front side of the first weight 31 and the third weight 33 are forgotten to be connected, the third weight 33
The eccentric weight of the weight 33 or more causes the weights 33, 34, 35 of the third weight or more to fall to the rear side. At that time, the small projecting piece 32a collides with the lower surface of the third weight 33. And acts to prevent the fall.

Further, in this embodiment, the fourth weight 34
And the fifth weight 35 are configured as shown in FIG. Cutout step portions 34a, 34a, ... Are formed at the left and right ends of the fourth weight 34 on the upper surface side and the lower surface side, respectively, and one bracket 34b, 34b is provided at each cutout step portion on the upper surface side. In addition, a pair of two brackets 34c, 3 are provided on each notch step portion on the lower surface side.
4c is provided. Each of these brackets 34b,
34c is a position which does not protrude from each of the left and right side surfaces of the fourth weight 34, and the upper and lower surfaces. The brackets 34c, 34c on the lower surface side are pin-connected to the brackets on the third weight 33 side.

On the other hand, cutout steps 35a, 35a are formed at the left and right ends of the fifth weight 35 on the upper surface side and the lower surface side, respectively.
Is formed, and one bracket 35b, 35b is provided on each notch step portion on the upper surface side, and
A pair of brackets 3 for each notch on the lower surface
5c and 35c are provided. Upper bracket 3
5b and 35b are at positions that do not protrude from the left and right side surfaces and the upper surface of the fifth weight 35. Lower bracket 3
5c and 35c are located at positions that do not protrude from the left and right side surfaces of the fifth weight 35, but are made to project downward by a certain length. That is, when the fifth weight 35 is placed on the fourth weight 34, each of the lower brackets 35c, 35c has a respective upper surface side notch step portion 34 of the fourth weight 34.
It can be fitted in the a and 34a and can be connected to the upper brackets 34b and 34b of the fourth weight 34.

As described above, in the fourth weight 34 or the fifth weight 35, the upper brackets 34b, 35 of the upper side
If b is provided so as not to project upward from the upper surface of each weight, the weight positioned at the uppermost stage is used regardless of whether the weight is used up to the fourth weight 34 or the fifth weight 35 is used. The upper bracket (34b or 35b) does not project upward from the upper surface of the weight, and the height of the entire counterweight 3 can be reduced accordingly.

A grounding base 35d is provided at the central portion of the lower surface of the fifth weight 35 in the left-right direction so as to project downward by the same length as the downward projecting length of each of the lower brackets 35c, 35c. The grounding base 35d has a rectangular plane portion having a considerable area in the central portion, and further has front and rear end portions of the plane portion having small front and rear plate members 35e, 35e, respectively.
Are attached together. The front-rear length of the grounding base 35d (the length including the plate members 35e, 35e) is formed to be slightly shorter than the front-rear width of the fifth weight 35. Then, when the fifth weight 35 is placed on the ground or on the truck bed, the fifth weight 35 is placed on the planar grounding platform 3
5d and two left and right lower brackets 35c and 35c
I am able to support points. At that time, since the grounding base 35d has a considerable length in the front-rear direction, even if the three points serving as the supporting legs are arranged in a straight line position,
The weight 35 does not grind in the front-back direction, and the installation posture is stable. Further, when the fifth weight 35 is placed on, for example, a truck carrier, the planar portion of the grounding base 35d comes into contact with the fifth carrier 35 so that the truck carrier is not damaged.

Further, a notch recess 34d for fitting the above-mentioned grounding base 35d when the fifth weight 35 is placed on the fourth weight 34 is formed in the center of the upper surface of the fourth weight 34 in the left-right direction. There is. The width of the cutout recess 34d is about 300 mm. Then, when the fifth weight 35 is overlaid on the fourth weight 34, the grounding base 35d is fitted into the cutout recess 34d as indicated by reference numeral 35d '. In this state, the grounding base 35d is provided at each of the front and rear ends of the cutout recess 34d. There is still space for foot rests. That is, in the state where the grounding base 35d is fitted into the cutout recess 34d, spaces for inserting feet are secured on the left and right sides of the plate members 35e, 35e projecting forward and backward. In FIG. 4, reference numerals 34f and 35f denote counterweights 3.
The grip bars 34g and 35g for climbing up are also recesses for hanging feet when climbing over the counterweight 3.

[0037]

The counterweight weight detecting apparatus of the present invention has the following effects. That is, when the support device 4 is caused to support a number of weights (for example, the fifth weight 35) exceeding a predetermined number (for example, the first to fourth weights 31 to 34), the center of gravity G of the entire counterweight 3 is viewed from the side. In the above, the support fulcrum P is deviated to the rear side from the vertical line Q, and the eccentric weight causes an action of rotating the entire counterweight 3 in the clockwise direction about the support fulcrum P. At that time, a part of the counterweight 3 (abutting pin 62) strongly abuts on the lower surface (receiving member 61) of the swivel base 2 in front of the support fulcrum P, and the abutting portion (abutting pin 62). A downward reaction force F acts on 62). The reaction force F acts to push down the support fulcrum P of the support device 4 downward, and as a result, a load larger than the actual weight of the excess weight (fifth weight 35) is applied to the support device 4 (hydraulic cylinder 41). As a result, the weight detector 5 detects a load larger than the actual excess weight. Therefore, even if the weight of the excess weight (fifth weight 35) is relatively light (for example, about 6 tons), the operator can clearly confirm in the cab 11 whether or not the excess weight is loaded. The effect is that you can do it.

[Brief description of drawings]

FIG. 1 is a partial side view of a mobile crane using a counterweight weight detection device according to an embodiment of the present application.

FIG. 2 is a plan view of FIG.

FIG. 3 is an operation explanatory view of the weight detection device for the counterweight shown in FIG.

FIG. 4 is a perspective view of a fourth weight and a fifth weight used in the weight detecting device for the counterweight shown in FIG.

5 is a graph showing the operation of the counterweight weight detection device of FIG. 1. FIG.

FIG. 6 is a partial side view of a crane vehicle that employs a conventional counterweight weight detection device.

[Explanation of Codes] 1 is a mobile crane, 2 is a swivel base, 3 is a counterweight,
4 is a support device, 5 is a weight detector, 21 is a rear end of the swivel base,
31 to 35 are weights, 41 is a hydraulic cylinder,
G is the center of gravity of the counterweight, and P is the support fulcrum of the support device.

Claims (1)

[Claims] 1. A rear end portion (2) of a swivel base (2) of a mobile crane.
The supporting device (4) attached to (1) supports a counterweight (3) consisting of an appropriate number of weights (31 to 35), and each of the weight detectors (5) provided on the supporting device (4) supports the counterweight (3). A counterweight weight detection device for a mobile crane, configured to detect the total weight of the weights (31 to 35), wherein a predetermined number of weights (31 to 3) are attached to the support device (4).
4) When the number of weights (35) exceeding the number of 4) is supported, the center of gravity (G) of the entire counterweight (3) is behind the swivel base (2) from the support fulcrum (P) of the support device (4). And the front side of the counterweight (3) supported by the support device (4) pivots upward by a slight amount about the support fulcrum (P) due to the eccentric weight of the counterweight (3). And the swivel base (2) from the support fulcrum (P) of the support device (4).
A counterweight weight detecting device for a mobile crane, wherein a part of the counterweight (3) abuts at an appropriate position of the swivel base (2) on the front side of the.