JPS6119556B2 - - Google Patents

Description

[Detailed Description of the Invention] In general, in the case of a telescopic boom of a truck crane, both side wall plates receive sunlight unevenly in most cases, so the difference in thermal expansion between the two side wall plates causes the telescopic boom to bend sideways. However, as truck cranes become larger and the maximum length of the telescopic boom is increased to around 50 meters, this lateral bending becomes impossible to ignore, and the margin given for strength and prevention of crane overturning when setting the rated load curve becomes difficult to ignore. That won't cover it.

The present invention addresses this problem, and is characterized in that: (1) a blower is attached to at least one end of the telescopic boom so as to blow outside air vertically into the telescopic boom, and a control device for the blower is provided. A device to prevent horizontal bending of a telescopic boom.

(2) Attach a blower to at least one end of the telescoping boom so as to blow outside air vertically into the telescoping boom, and attach a detection device to the telescoping boom to detect left and right bending of the boom, and install the detection device. hand,
A device for preventing side bending of a telescopic boom, comprising: an automatic control device that drives the blower while receiving a side bend signal issued by the detection device.

The gist is:

The figure shows one embodiment of the present invention, and FIG. 1 shows a telescopic boom consisting of four boom tubes 1, 2, 3, and 4, which is extended and retracted by a hydraulic cylinder. Direct sunlight S is exposed on one side of the telescopic boom. When the telescopic boom bends horizontally in an arc shape as shown by the chain line, the tip of the boom swings horizontally by an amount L. F is a foot pin that pivots the base end of the telescopic boom to the swivel base so that it can be raised and lowered.

Reference numeral 5 denotes a pressurized propeller blower attached to the upper part of the base end of the base end boom cylinder 1, and the propeller 6 is driven at high speed by a hydraulic motor 8 in the fuselage 7 via a gear speed increasing mechanism 9. The air is then blown towards the tip of the telescopic boom. In the illustrated case, the pressurized propeller blower 5 is attached only to the base end of the telescopic boom, so the base end opening of the base boom tube 1 is sealed with a lid 11 except for the suction port 10 of the propeller blower. .

The detection device is arranged symmetrically within the base end of the proximal boom tube 1, sandwiching a light emitting section 12 such as a laser beam installed in the tip of the boom tube 4 and a light beam R emitted from the light emitting section 12 when the boom is in a straight state. It includes the light receiving sections 13 and 14 on both sides attached with. The light ray R is located in a vertical plane that includes the axis of the telescopic boom, and the light receiving sections 13 and 14 receive the light ray R regardless of the magnitude of bending strain in the vertical plane of the telescopic boom due to the lifting load or direct sunlight. Increase the vertical length to get the desired result.

The automatic control device is arranged between the light receiving sections 13 and 14 and the electromagnetic directional switching valve 15 that controls the hydraulic motor 8, and while the light receiving section is receiving the light beam (signal) R, the directional switching valve is operated as shown in FIG. Electrical circuit 1 switching to the lower position of
6 is provided. Note that 17 is a hydraulic pump, 18 is a tank, and 19 is a diode.

The hydraulic cylinders that extend and contract between adjacent boom tubes are hydraulic cylinders 2 installed between boom tubes 1 and 2.
0, the tip of the piston rod P is pivotally attached 21 within the base end of the proximal boom barrel, and the piston rod insertion side end of the cylinder is pivotally attached 22 within the proximal end of the distal boom barrel. , each of the hydraulic cylinders 20, etc., are arranged so as to be offset to the lower part and side of the telescopic boom as much as possible so as not to interfere with the light beam R.

According to the above configuration, when the extended telescopic boom is in a substantially straight state, the light ray R emitted from the light emitting part 12 is transmitted to the light receiving parts 13 and 14 as shown by the solid line in FIG.
The directional control valve 15 maintains the illustrated cutoff position and the blower 5 is stopped because the air passes through the space between the air and the air.

When this telescopic boom receives direct sunlight S on one side, it bends sideways as shown by the chain line in FIG. 1 or FIG. When the telescopic boom bends in the opposite direction due to direct radiation and the light beam illuminates the light receiving section 14,
In response to this signal, the directional control valve 15 is switched to the lower position and drives the blower 5, so that the outside air becomes a turbulent flow and flows through the telescopic boom, and the boom side opposite to the boom side wall plate that is directly exposed to sunlight. Reduce the temperature difference between the side wall plates and return the telescopic boom to its straight position. For this reason, there is no problem even if the air blowing temperature increases on the boom tip side due to the temperature rise of the blower, boom extension/retraction hydraulic cylinder, etc.

In this way, when the telescopic boom returns to a substantially straight state and the light beam R passes through the portion between the light receiving sections 13 and 14, the light receiving section no longer receives the signal, so the directional control valve 15 is shut off as shown in the figure by its own return spring. It returns to the position and the blower 5 stops.

The reason why the blower 5 is installed at the upper part of the base end of the telescoping boom is to further reduce the temperature difference between the boom tubes 2 and 2 on the boom top side, which is easily exposed to direct sunlight. This is to minimize the decrease in the lengths of 3 and 4.

Although one embodiment has been described above, if there is strong direct sunlight, the blower may be driven constantly during crane operation. It is clear that an automatic control device for the blower by means of a signal is not necessarily required.

Furthermore, even if a detection device is installed to detect horizontal bending of the telescopic boom, the detection device is not limited to the configuration shown in the drawings, and strain gauges are installed on the outer surfaces of both sides of at least one boom tube to directly detect the bending of the boom. Any configuration may be adopted, such as one that detects lateral bending.

According to the present invention, since the temperature difference between the side wall plates of the telescopic boom can be reduced, the boom length when extended is 50 mm.
Even if the temperature is around 1000 yen or more, the horizontal bending of the telescopic boom due to sunlight can be suppressed within a safe range, and damage to the telescopic boom can be prevented.

[Brief explanation of the drawing]

FIG. 1 is a plan view of the extended telescopic boom, FIG. 2 is a plan view schematically showing a detection device and a control device, and FIG. 3 is a longitudinal sectional side view of the base of the telescopic boom. 1, 2, 3, 4... Boom tube, 5... Propeller blower, 8... Hydraulic motor, 12... Light emitting part, 1
3, 14... Light receiving section, 15... Electromagnetic directional control valve,
16...Electric circuit.

Claims (1)

[Claims] 1. A method for preventing horizontal bending of a telescopic boom, characterized in that a blower is attached to at least one end of the telescopic boom so as to blow outside air vertically into the telescopic boom, and a control device for the blower is provided. Device. 2. A device for preventing side bending of a telescopic boom as set forth in claim 1, wherein a propeller blower is attached to the upper part of the base end of the telescopic boom. 3. A blower is attached to at least one end of the telescopic boom so as to blow outside air vertically into the telescopic boom, and a detection device is attached to the telescopic boom to detect left and right lateral bending, and the lateral bending generated by the detection device is installed. A device for preventing sideways bending of a telescopic boom, characterized in that an automatic control device is provided to drive the blower while receiving a signal. 4. A device for preventing side bending of a telescoping boom as set forth in claim 3, wherein a propeller blower is attached to the upper part of the base end of the telescoping boom.