JPH04256688A - Safety device for preventing drop of hanging object - Google Patents

Abstract

PURPOSE:To provide a drop preventive safety device for versatile application, with which falling of a suspending object can be sensed automatically and checked, using a simple and compact configuration requiring no power motive. CONSTITUTION:An elevating/sinking element is coupled with a support through a hydraulic cylinder 11, and a hydraulic closed loop circuit 12 is formed including the cylinder, and in this circuit an orifice 12a and a pilot-operated opening/ closing valve 12b are inserted. Pilot pressure of this valve is extracted from a pipeline on the side where the working oil flows into the orifice when the elevating/sinking element falls, and the valve is turned to the close side by the use of pressure rise on the inflowing side of the orifice at the time of dropping. Thereby the piston of the hydraulic cylinder is locked, and the elevating/ sinking element mis hindered from displacing relative to the support.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a safety device for preventing a lifting object including a suspended object from falling in lifting equipment for suspending heavy objects.

0002

[Prior Art] Conventionally, various types of safety devices have been adopted in lifting equipment for suspending heavy objects in transportation systems, etc., in order to prevent accidents of lifting objects including suspended objects from falling. Most of these are unique to individual lifting equipment, that is, appropriate configurations are adopted based on the mechanism of the lifting equipment. For example, in a mechanism in which an elevating object is guided by a support body by a guide rod, etc., the falling of the elevating object is detected by some kind of sensor using the guide rod, etc., and in that case, the surrounding area relative to the guide rod is detected. Mechanisms such as adding a clamp or driving a notch into the guide rod are used.

0003

[Problems to be Solved by the Invention] By the way, in all conventional safety devices of this type, there are problems in the method of detecting the fall of the elevating object and the mechanism for emergency stopping the elevating object when a fall is detected.
In addition to requiring some kind of power such as electricity or hydraulics, the device configuration is large-scale and expensive.Furthermore, there is no one that can be used universally for lifting equipment of various mechanisms, so it is difficult to use existing lifting equipment. There is a problem in that it is difficult to wear.

The present invention has been made in view of the above points, and an object of the present invention is to provide a suspended load fall safety device that does not require power, has a simple and inexpensive configuration, and can be easily attached to existing lifting and lowering maintenance equipment. The purpose is

[0005]

[Means for Solving the Problems] In order to achieve the above object, the present invention provides, as shown in FIGS. 1 and 2 corresponding to the embodiments, the main body is attached to either the support body or the elevating body. It also consists of a hydraulic cylinder to which the piston is fixed, and a hydraulic circuit attached to the hydraulic oil input/output port of the hydraulic cylinder. In addition to forming a closed circuit, an orifice and a pilot pressure-operated on-off valve are inserted into the hydraulic circuit, and the pilot pressure of the on-off valve is applied to the hydraulic fluid in the orifice in the hydraulic circuit when the elevator is lowered. It is characterized by being taken out from the pipe on the side that flows into the pipe.

[0006]

[Function] When the elevating body is raised and lowered relative to the support, a relative displacement occurs between the main body and the piston in the hydraulic cylinder.
Hydraulic oil flows in a closed hydraulic circuit. The flow rate of hydraulic oil during normal lifting and lowering operations is relatively slow, and pressure increases on the inlet side of the orifice due to hydraulic oil passing through the orifice during both ascending and descending operations are small. On the other hand, when the elevating body falls, the relative speed between the main body of the hydraulic cylinder and the piston increases due to this fall, and therefore the hydraulic fluid rapidly flows within the hydraulic closed circuit and attempts to pass through the orifice. This increase in flow to the orifice causes a sudden increase in the pressure in the pipeline on the inflow side of the orifice, which operates the on-off valve from which pilot pressure is taken out, shutting off the oil passage in the hydraulic closed circuit and causing the piston to move. lock.

[0007]

Embodiment FIG. 1 is a front view showing an embodiment of the present invention attached to lifting equipment. This example shows a case where the present invention is applied to a lifting equipment in which a support body supporting a lifting body is driven to travel along a running rail. Suspended object W
Hook 21 for attaching and detaching (hereinafter referred to as hanging load W)
The carriage 20, which includes a drive mechanism 22, is supported by a frame 31 of a traveling truck 30 so as to be vertically displaceable along a guide rod 23.

Wheels 32 are attached to both ends of a frame 31 of the traveling truck 30, and the vehicle can travel along a traveling rail 50 on a traveling rail mounting beam 51. The traveling truck 30 includes a ball screw jack 41 and a motor 42 with a brake for driving the ball screw jack 41.
An elevating drive mechanism 40 consisting of the like is provided, and is configured such that the elevating mechanism 40 can move the carriage 20 up and down with respect to the traveling carriage 30. That is, the frame 41b of the ball screw jack 41 is attached to the frame 31 of the traveling truck 30, and the ram 4
The tip of 1a is fixed to the carriage 20, and the carriage 2 is moved by driving a motor 42 with a brake.
0 goes up and down.

[0009] In the above-mentioned lifting equipment, with the hanging load W hooked by the hook 21, the lifting drive mechanism 40 is driven to raise the carriage 20, and the traveling carriage 30 is given a traveling motion to lift the hanging load W. is transported in the direction in which the running rail 50 extends while being lifted to a predetermined height. Now, the suspended load fall prevention safety device 10 based on the present invention includes a hydraulic cylinder 11 and a hydraulic closed circuit 1, as described later.
In this example, a double-rod type hydraulic cylinder 11 is used, and its cylinder frame portion 11a is connected to the traveling carriage 3 via a fixture 11b.
0 frame 31, and the piston rod 1
The distal end (lower end) of 1c is fixed to the carriage 20 and installed in the equipment. In addition, in this FIG. 1, 10a is a hydraulic circuit unit which accommodates the hydraulic circuit member mentioned later.

FIG. 2 is a circuit diagram showing the configuration of a hydraulic circuit according to an embodiment of the present invention. An orifice 12a is connected to the lower hydraulic oil input/output port 11d of the double rod type cylinder 11 via a pipe line 121.
communicates with one port A of a pilot-operated two-port two-position switching valve 12b through a conduit 122. The other port B of this switching valve 12b is connected to the hydraulic oil input/output port 11e on the upper side of the hydraulic cylinder 11 through a conduit 123, forming a hydraulic closed circuit 12 as a whole.

The 2-port 2-position switching valve 12b is set so that its normal position is in the open state as shown in the figure, and when a pilot pressure higher than a predetermined pressure is supplied, the spool is driven and the valve is closed. state. This switching valve 12b
The pilot pressure is taken out from line 121. The hydraulic cylinder 11 is selected to have a bore and pressure resistance that can sufficiently withstand the sum of the maximum load suspended by the carriage 20 and the weight of the carriage 20, and the diameter of the orifice 12a is determined by the diameter of the orifice 12a. 20 and the pilot pressure PP for driving the spool of the 2-port 2-position switching valve 12b.
In relation to this, it is determined as described below.

Now, in the embodiment of the present invention described above, when the carriage 20 moves up and down, the hydraulic oil flows within the hydraulic closed circuit 12. This flow creates a pressure difference between the inflow side and the outflow side of the hydraulic oil to the orifice 12a, and the pressure on the inflow side increases. This pressure difference, and therefore roughly the inflow side pressure value, is
If the diameter of the orifice 12a and the specific weight of the hydraulic oil used are constant, it depends on the flow rate of the hydraulic oil to the orifice 12a, that is, the flow rate of the hydraulic oil within the hydraulic closed circuit 12.

Since the flow speed of the hydraulic oil is proportional to the displacement speed of the piston in the hydraulic cylinder 11 and therefore to the vertical movement speed of the carriage 20, the pressure on the hydraulic oil inflow side of the orifice 12a is approximately equal to that of the carriage 20. It depends on the lifting speed. Therefore, the diameter of the orifice 12a is
Pressure P generated on the inflow side of the orifice 12a when the carriage 20 moves up and down at maximum speed in the normal driving state
N is lower than the pilot pressure PP of the switching valve 12b, and when the carriage 20 reaches the speed expected to fall, the inlet side of the orifice 12a (pipe line 121
) is selected so that the pressure PC generated is higher than the pilot pressure PP.

As a result, when the carriage 20 is normally raised and lowered, the 2-port 2-position switching valve 12b maintains the normal state, that is, the open state, and if the carriage 20 is damaged due to some reason such as damage to the ball screw jack 41 or damage to the motor with brake 42, When 20 tries to fall, 2 port 2
The position switching valve 12b is brought into a closed state by the pilot pressure, and the pipeline of the hydraulic closed circuit 12 is cut off. By blocking this line, the piston of the hydraulic cylinder 11 is locked, preventing the carriage 20 from descending.

The present invention also includes the use of a hydraulic circuit member having an equivalent function, such as a choke, in place of the orifice 12a in the above-described embodiments of the present invention. However, the choke is not very preferable because the inlet and outlet pressure difference depends on the viscosity of the hydraulic oil, and the operating speed of the device changes depending on the ambient temperature. Also, in the example above,
The main body frame side of the hydraulic cylinder was attached to the support body (traveling body) side, and the piston side was attached to the elevating body (carriage) side.
You can also replace these.

Furthermore, in the embodiment of the present invention described above, by using a double rod type hydraulic cylinder, the carriage 2
0, the movement of the piston was made possible by matching the flow rate of hydraulic oil flowing in and out of both hydraulic oil input and output ports of the hydraulic cylinder 11. However, by adopting the configuration shown in FIG. Even if a hydraulic cylinder is used, exactly the same effect can be achieved.

That is, in this example, two single-rod hydraulic cylinders 71 and 81 of the same type are used, and the main body frame side and piston side of each hydraulic cylinder 71 and 81 are opposite to each other, for example, the main body frame side and the piston side of each hydraulic cylinder 71 and 81 are opposite to each other. The frame side is fixed to the support body (traveling body 30), the piston side is fixed to the elevating body (carriage 20), and the cylinder 81
For this, fix the main body frame side to the elevating body and the piston side to the elevating body. Then, the hydraulic oil input and output ports of the cylinders 71 and 81 are connected to each other by a pipe line as shown in the figure, and an orifice 12 similar to the above example is installed on this pipe line.
a and the 2-port 2-position switching valve 12b. With this configuration, the difference in the flow of hydraulic oil in and out due to the presence of the piston rod of each cylinder is mutually canceled out between the two cylinders, and no malfunction occurs in the cylinders 71 and 81 when the elevating body is raised or lowered. According to this example, although two cylinders are required, there is an advantage that the height of the device can be kept low.

The present invention is of course applicable to all kinds of lifting equipment in addition to the lifting equipment with the structure shown in FIG. 1, and can be applied to any existing lifting equipment. Can be installed.

[0019]

As explained above, according to the present invention, a hydraulic cylinder is interposed between the elevating body and the support body, and this hydraulic cylinder is connected to the orifice and the pilot-operated two-port two-position switching valve. It is inserted into a hydraulic closed circuit equipped with an on-off valve (on-off valve), and when the lifting object falls, the pilot pressure that utilizes the pressure increase on the hydraulic oil inflow side of the orifice drives the switching valve to open the pipeline of the hydraulic closed circuit. cut off,
Since the hydraulic cylinder is configured to lock, no power source is required, and the compact configuration with an extremely simple mechanism and hydraulic circuit automatically detects and prevents the fall of the lifting object. It can be easily added to not only newly installed lifting equipment but also existing lifting equipment.

[Brief explanation of the drawing]

[Fig. 1] A front view showing the embodiment of the present invention installed in lifting equipment.

[Fig. 2] A circuit diagram showing the configuration of a hydraulic circuit according to an embodiment of the present invention.

[Figure 3] Explanatory diagram of the configuration of another embodiment of the present invention

[Explanation of symbols]

10...Safety device for preventing suspended loads from falling 11...Double rod type hydraulic cylinder 12...Hydraulic closed circuit 12a...Orifice 12b...Pilot operated 2-port 2-position switching valve 121 , 122, 123...Pipe line 20...Carriage 21...Hook 23...Guide rod 30...Traveling trolley 31...Frame 32...Wheel 40... ... Lifting drive mechanism 41 ... Ball screw jack 42 ... Motor with brake 50 ... Traveling rail W ... Suspended object

Claims (1)

[Claims] Claim 1: A device for preventing falls in a device comprising a support body and an elevating body supported by the support body and driven vertically relative to the support body while grasping a suspended object. The safety device comprises a hydraulic cylinder whose body frame side is fixed to either one of the support body and the elevating body and whose piston side is fixed to the other, and a hydraulic circuit attached to the hydraulic oil input/output port of the hydraulic cylinder. This hydraulic circuit forms a closed circuit including the hydraulic cylinder via the hydraulic oil input/output port, and an orifice and a pilot pressure-operated on-off valve are inserted into the circuit. A safety device for preventing a suspended load from falling, characterized in that the pilot pressure of the opening/closing valve is taken out from a pipe on the side of the hydraulic circuit in which hydraulic oil flows into the orifice when the elevating body is lowered.