JPS5834400B2 - Boom Moment Seigen Sochi - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a self-propelled crane having a boom consisting of a telescoping boom and an add-on boom that can take two positions: an extended position at the tip of the telescoping boom and a retracted position where it is not extended. This invention relates to a boom moment limiting device.

In a self-propelled crane configured in this way, there are two values: an actual value corresponding to the moment in the direction of overturning the boom that is generated around the boom hoisting fulcrum, and a limit value that is suddenly switched in response to the extension and contraction state of the telescoping boom. In contrast, a boom moment limiting device is installed that generates a signal to limit the movement of the self-propelled crane when the measured value reaches a limit value to ensure crane work safety.

In this type of boom moment limiting device, the more frequently the limit value is suddenly switched in response to the extension/retraction state of the telescoping boom, the more approximate the performance limit of the self-propelled crane will be. However, frequent switching of limit values in this way requires storing a large number of limit values, which makes the boom moment limiter itself complicated and expensive, and it is difficult to change the limit value. To explain a self-propelled crane that has a telescopic boom that is complicated to operate, and a retractable boom that can take two positions at the tip of the telescopic boom, an extended position and a retracted position that does not extend, In Figure 1, a self-propelled crane A has a distal end boom section 2 telescopically inserted into a proximal boom section 1, and both boom sections 1,
A telescoping boom 4 that is telescopically operated by a hydraulic telescoping cylinder 3 interposed between the telescoping boom 4, an overhanging position at the distal end of the boom section 2 on the distal end side of the telescoping boom 4 (solid line position in Figure 1), and a side surface of the telescoping boom 4. It has a boom 6 consisting of an additional boom 5 that can take two positions: a retracted position along the line, that is, a retracted position in which it does not extend (dash line position in FIG. 1).

The boom 6 connects the base end of the base end boom section 1 to a swivel base 8 mounted on a vehicle 7 so as to be rotatable in a horizontal plane. By the action of a hydraulic cylinder 10 disposed between appropriate positions in the section 1, the vertical movement is performed using the pivot 9 as a fulcrum.

At the tip of the boom section 2 on the tip side of the telescoping boom 4, a hanging tool 11 is provided which is operated to be hoisted up and lowered by a winch (not shown) provided on the swivel base 8.

The hoist 11 is used when hoisting up and lowering a load with the replenishment boom 5 in the retracted position (hereinafter referred to as crane work at the tip of the telescopic boom 4).

Further, at the tip of the replenishment boom 5 in the extended position, a hanging tool 12 is provided which is operated to be hoisted up and lowered by a winch (not shown) provided on the swivel base 8.

The hoist 12 is used when the replenishment boom 5 is in an extended position (hereinafter referred to as crane work at the tip of the replenishment boom 5).

In the self-propelled crane A configured in this way, looking at the relationship between the moment generated around the boom hoisting fulcrum 9 during each crane operation and the maximum allowable lifting load, first, during crane operations at the tip of the telescopic boom 4. The actual maximum allowable lifting load of the self-propelled crane increases as the telescopic boom 4 is reduced (the maximum allowable lifting load is determined based on the stability of the self-propelled crane or the strength of the telescopic boom 4). Since both stability and strength increase as the telescopic boom 4 is reduced, the maximum lifting load naturally increases.

). On the other hand, as the telescopic boom 4 contracts, the moment around the boom hoisting fulcrum is affected by the arm that affects the moment, that is, the length of the telescopic boom 4 decreases.If you try to obtain the same moment value, the suspended load will gradually decrease. It has to be bigger.

In this way, the increase in the actual maximum allowable lifting load due to the contraction of the telescopic boom is the same as the increase in the lifting load when the moment generated around the boom's fulcrum in the direction of lodging the boom is kept constant. It matches well.

In fact, the relationship between the boom moment limit value during crane work at the tip of the telescoping boom 4 and the extension state of the telescoping boom (telescopic boom length l) is as shown by the solid line in Fig. 5(a). There is.

Therefore, the boom moment limiting device
During crane work at the tip, it is possible to cover a wide range of telescopic boom telescopic range with a certain limit value.

For this reason, when working with the crane at the tip of the telescopic boom 4,
The extended state of the tip side boom section 2, that is, the range from the start of extension of the tip side boom section 2 to the fully extended state, is covered within the practical range with a constant boom moment limit value as shown by the dotted line in Fig. 5 (a). It is possible.

Next, considering the case of crane work at the tip of the refill boom 5, since the refill boom 5 is used to compensate for the lack of length of the telescopic boom 4, its most frequent use is when the retractable boom 5 is at its maximum extension. It is clear that they are used together.

Furthermore, since the refill boom 5 is located at the tip of the telescopic boom 4 when in use, the greater the weight of the refill boom 5, the more the crane performance is reduced.

For this reason, it is preferable to reduce the weight of the refill boom 5 as much as possible, and in that sense, the weight of the refill boom 5 is
In order to reduce the weight, the structure is manufactured so as to meet the minimum strength required in the mode in which it is most frequently used, that is, in the mode in which it is used with the telescopic boom 4 in its most extended state.

In other words, when the additional boom 5 is added to the tip of the telescoping boom 4 and the telescoping boom 4 is brought to its maximum extension, the self-propelled crane A does not have enough strength to lift the maximum allowable lifting load. , it doesn't have any more strength.

When suspending cargo from the tip of the boom 5 with the extension boom 5 extended to the tip of the telescopic boom 4, the actual maximum lifting distance is different from when working with a crane at the tip of the boom 4. It is clear that the permissible load does not increase by reducing the telescopic boom 4.

That is, the relationship between the boom moment limit value during crane work at the tip of the supplementary boom 5 and the extended state of the telescoping boom (telescopic boom length l) is as shown by the solid line in FIG. 5(b).

If a boom moment limiter is used to cover the extended state range of the tip side boom section 2 during crane work using the additional boom 5 with a certain boom moment limit value, there is a risk that the additional boom 5 will be destroyed. comes out.

This is because the limit value of the boom lodging direction moment allowed in the state where the replenishment boom 5 is used together with the telescopic boom 4 at its maximum extension, that is, the most frequent usage mode of the replenishment boom 5, is set as the limit value of the boom moment limiter.
When trying to cover the entire extended state range of the distal boom section 2, the actual measured value of the moment in the lodging direction generated around the hoisting fulcrum of the telescopic boom 4 decreases as the distal boom section 2 contracts (moment arm decreases with the contraction of the telescopic boom 4), and as a result, it becomes possible to lift a large load.

This results in the boom moment limiter not being able to monitor the safety of a supplementary boom that only has the required strength when used with the telescopic boom 4 in its fully extended state.

The present invention provides a telescopic boom in which a distal end boom section is telescopically inserted into a proximal boom section in order and a hydraulic telescopic cylinder is interposed between adjacent boom sections, and a distal end of a distal end boom section of the telescopic boom. Used in self-propelled cranes that have a boom consisting of a removable boom that can take an extended position and a retracted position that is not extended. This relates to a boom moment limiting device that compares a limit value that is suddenly switched in response to the boom's extension/retraction condition, and generates a signal to limit the movement of a self-propelled crane when the actual measured value reaches the limit value. In particular, by reducing as much as possible the sudden switching of the limit value in the extended state range of the most advanced boom section of the telescopic boom, taking into account the characteristics of the self-propelled crane described above, the memory limit The present invention aims to provide a boom moment limiting device with a simple structure and switching operation by reducing the number of values.

Embodiments of the present invention will be described below with reference to FIGS. 1 and 2.

13 is a boom moment limiting device, and this boom moment limiting device 13 responds to the moment around the boom hoisting fulcrum 9, which is actually measured by a detector 15 that electrically detects the stress in the axial direction of the piston rod 14 of the hydraulic cylinder 10. The actual measured value is compared with a limit value that is suddenly switched depending on the extension/contraction state of the telescopic boom 4, and when the actual measured value reaches the limit value, a signal is generated to limit the movement of the self-propelled crane A. However, sudden switching of the limit value according to the telescoping state of the telescoping boom 4 is possible through the common contact 18 and the input terminal 19 of the boom moment limiter 13.
. A manual switch 28 selectively connected to common contacts 18 and 22 at 21.degree. 25 is used to suddenly switch the limit value.

And the boom moment limiter 13 has its input terminal 1
By supplying power to input terminal 9, the limit value corresponding to the maximum contraction of the tip side boom 2 during crane work at the tip of the telescopic boom 4 is set, and by supplying power to its input terminal 20, the limit value corresponding to the maximum contraction of the tip side boom 2 is set during crane work at the tip of the telescopic boom 4. The limit value corresponding to the extension of the tip side boom section is input to its input terminal 2.
By supplying power to the input terminal 24, the limit value corresponding to the maximum extension of the tip side boom section 2 during crane work at the tip of the supplementary boom 5 is set by applying power to the input terminal 24. It is switched so as to produce a limit value corresponding to when the distal end boom section 2 is contracted (when the distal boom section 2 is in a state other than the maximum extension state).

The relay switch 21 is operated by a limit switch 29 which is provided at the tip of the proximal boom section 1 and detects the most contracted state of the tip boom section 2, and the limit switch 29 detects the most contracted state of the tip boom section 2. When the limit switch 29 detects the extended state of the tip side boom section 2, the common contact 18 and the input terminal 19 of the boom moment limiter 13 are connected. The terminal 20 is configured to be connected thereto.

Further, the relay switch 25 is operated by a limit switch 30 which is provided at the tip of the proximal boom section 1 and detects the maximum extension state of the distal boom section 2,
When the limit switch 30 detects the maximum extension state of the tip side boom section 2, the common terminal 22 and the input terminal 23 of the boom moment limiter 13 are connected, and the limit switch 30 detects the contracted state of the tip side boom section 2. The common terminal 22 is sometimes connected to the input terminal 24 of the boom moment limiting device 13.

Next, to explain the operation, when performing crane work at the tip of the telescopic boom 4, the common contact 27 of the manual switch 28
is used by connecting it to the common contact 18 of the relay switch 21. However, as mentioned above, the relay switch 21 switches depending on whether or not the tip end boom section 2 is in the most contracted state. The limit value is switched depending on whether or not the tip end boom section 2 is in the most contracted state.

Also, when performing crane work at the tip of the refill boom 5, the common contact 27 of the manual switch 28 is connected to the common contact 22 of the relay switch 25.
As mentioned above, the relay switch 25 is switched depending on whether the tip side boom section 2 is in the fully extended state or not.
The limit value of the boom moment limiting device 13 is switched depending on whether or not the tip side boom section 2 is in the maximum extension state.

The boom moment limiter 13 constructed and operated in this manner is well suited to the characteristics of the above-mentioned self-propelled crane and satisfactorily achieves its intended purpose.

The above embodiment was implemented on a self-propelled crane having a two-stage telescoping boom, and the limit value was switched according to the extension/contraction state of the tip side boom section 2. However, the present invention allows switching of the limit value. This can be applied to telescoping booms with three or more stages by adjusting the extension and contraction state of the most distal boom section.

When applied to a three-stage telescoping boom (FIG. 3) consisting of a proximal boom section 101, an intermediate boom section 102, and a most distal boom section 103, limit switches 29 and 30 in the above embodiment are used. That is, a limit switch 10 provided at the tip of the intermediate boom section 102 to detect the most contracted state of the tip boom section 103.
4. In order to detect the maximum extension state of the distal end boom section 103, it is necessary to transmit the detection signal of the limit switch 105 provided at the distal end of the intermediate boom section 102 to the proximal boom section 101. It may be transmitted by a two-wire electric coil that is freely wound up and unwound on a cord winder, or by grounding one end of the limit switch 104 directly to the intermediate boom 102 as shown in FIG. Connect one end of the limit switch 105 to a resistor R
The intermediate boom 102 is connected to the base end boom section 101 through a cord winder 106, and the other end of each limit switch 104, 105 is wound up by a cord winder 106. lead it to the side and connect it to relay 1
07 to the power supply 26 and this relay 10
It is also possible to transmit the signal before and after the relay 108 and the relay switch 107', which is disconnected when the relay 107 is activated, by a signal transmission circuit interposed in series.

That is, in the signal transmission circuit configured as described above, the relay 107 is set to operate when the limit switch 104 is connected, and the relay 108 is set to be activated when the limit switch 105 is connected. , the relay 107 is activated when the most advanced boom section 103 is contracted, and the relay 108 is activated when the most advanced boom section 103 is contracted.
03, respectively, so the limit value of the boom moment limiter can be switched by the relay switch operated by the relays 107 and 108.

When configured in this way, two detection signals can be sent to the proximal boom section 101 side with a simple design.

In any case, the present invention provides a telescopic boom in which a distal end boom section is telescopically inserted into a proximal boom section in order and a hydraulic cylinder is interposed between adjacent boom sections, and a distal end boom section of the telescopic boom. This is the actual measured value in response to the moment generated around the fulcrum of the boom used in a self-propelled crane that has a boom consisting of an additional boom that can take two positions: an extended position at the tip of the boom and a retracted position where it is not extended. and a limit value that is suddenly switched in response to the extension and contraction state of the telescoping boom, and when the actual measured value reaches the limit value, a boom moment limiter generates a signal to limit the movement of the self-propelled crane. , when suspending a load at the tip of the boom by adding a sudden change of the above limit value in the extended state range of the boom section on the farthest side of the telescopic boom and suspending the load at the tip of the boom, the boom section on the farthest side is the most When suspending cargo at the tip of the telescopic boom with the additional boom in the retracted position, the boom section is configured to do so depending on whether it is in the extended state or not. The sudden switching of the limit value in the extension state range of the most advanced boom section is reduced as much as possible,
This has the excellent effect of simplifying the structure of the boom moment limiting device and the switching operation of its limit value.

[Brief explanation of drawings]

Fig. 1 is an explanatory diagram of a self-propelled crane using the boom moment limiting device of the present invention, Fig. 2 is an explanatory diagram of the boom moment limiting device of the present invention, and Fig. 3 is an explanatory diagram of a three-stage telescoping boom. Figure 4 is an explanatory diagram of a signal transmission circuit used when implementing the present invention in a self-propelled crane having a three-stage telescopic boom, and Figure 5 shows the boom moment limit value and the extension state of the telescopic boom. 5(a) corresponds to crane work at the tip of the retractable boom, and FIG. 5(a) corresponds to crane work at the tip of the retractable boom. 4; Telescopic boom, 2; 103; Top end boom section, 3; Hydraulic telescopic cylinder, 5; Additional boom, 1
3; Boom moment limiter.

Claims (1)

[Claims] 1. A telescopic boom in which the distal end boom section is telescopically inserted into the proximal boom section one after another, with a hydraulic telescopic cylinder interposed between the adjacent boom sections, and an overhang extending from the tip of the distal end boom section of the telescopic boom. This is used for self-propelled cranes that have a boom consisting of a removable boom that can take two positions: a fixed position and a retracted position without overhanging. A boom moment limiting device that compares a limit value that is suddenly switched in response to the extension/retraction state of the boom, and generates a signal to limit the movement of a self-propelled crane when the actual measured value reaches the limit value. When a load is suspended from the tip of the boom by adding a sudden change of the above limit value in the extension state range of the boom section on the farthest side of the boom and suspending the load at the tip of the boom, the boom section on the farthest side is the most It is configured so that the operation is performed depending on whether the boom section is in the extended state or not, and when the additional boom is placed in the retracted position and the load is suspended from the tip of the telescopic boom, the operation is performed depending on whether the boom section on the most advanced side is in the extended state or not. A boom moment limiter featuring: