DE2164628A1 - OVERLOAD SHUT-OFF DEVICE FOR HYDRAULIC LIFTING AND LIFTING SYSTEMS ADJUSTMENT MECHANISMS, ESPECIALLY FOR HYDRAULIC LOADING CRANES - Google Patents

Description

Dipl.-Ing. Br.-Ing. HEINZ PATE V T AIT W AIiT

WESTF.

Wiederwall 8 (mm Jahnolatz)

Detmolderstrasse Il / sk. 12/22/1971

Dipl.-Ing. Dr. S, Gross, 4935 Detmold-Hiddesen, Rotdarnuieg 7

"Overload disconnection device for one behind the other hydraulic lifting bzui. l / creation mechanisms, in particular for hydraulic loading cranes "

The subject matter of the invention relates to an overload disconnection device for one behind the other hydraulic lift bzu. Setting mechanisms, especially bsi hydraulic loading cranes.

As is well known, a hydraulic loading crane can work with a short crane arm. A smaller radius can lift a larger load than is the case with a longer crane arm _{or a} larger radius. A loading crane can

309827 / 0U1

thus the maximum load can be lifted by the crane arm is fully retracted, however, after the lift, the outreach can be increased with the load hanging, for example, by hydraulically extending the arm or pivoting it outward, there is a risk of overloading the crane and its actuating elements.

Systems that have been used up to now, in which one has a hydraulic path achieved by a pressure reducing valve built into the hydraulic system Limited type of discharge or pressure adjustment valve, do not prevent the occurrence of such overloads and also have the disadvantage that the load can start at the overloads mentioned, to sink to uncontrollable means with a corresponding risk of damage to goods and accidents.

Even if the crane arm is sufficiently strong In order to withstand the aforementioned overload, the arm is also extended to the largest extent is, this does not change the fact that one is one

309827 / OUl. - 3 -

Can lift a significantly larger load if the lift is carried out with a small radius, and that at a subsequent enlargement of the arm extension, the risk of such overloads inevitably occurs. Under unfavorable conditions can overturn the whole arrangement · Such an enlargement of the projection can be different Way to be achieved, e.g. by extending the extendable part of the crane arm after lifting the Load, or for example in the case of a crane arm with Kapflenker a tilting arm, and the tilting arm follows When the load is raised, or when the crane arm is tilted up or down and with The hanging lathe is brought into a more horizontal position.

According to the accident prevention regulation, power-operated hoists and power-operated outrigger pull-in devices must have the Switch off if the permissible load torque is exceeded. This switch-off means that all movements if the permissible load torque is exceeded

3098 27 / 0U1

be brought to a standstill automatically, the one Cause an increase in the load torque. All movements for Laatmomentverrichterung must be carried out can uerden. The overload protection

^ is intended to prevent a certain off

Load exceeded the permissible limit for stability due to excessive load acceptance and there is a risk of tipping over. Safety devices are used on heavy automotive cranes on a mechanical basis with lever ratios, springs, gearshift crucibles etc. that operate electrical relays and switches. On the other hand, there are electronic load torque limiters known, consisting of pressure transducer

P (hydraulic pressure cylinder, strain gauge), Win

kel transducers (potentiometers) and electronic calculators. The measured values (actual values) from the angle encoder and Pressure transducers are compared with the setpoints in the computer. With a certain difference between the two linked switches a relay, the crane is shut down e.g. via an electropneumatic valve. the the aforementioned devices for overload protection

309827 / 0U1

- b -

are relatively high in production and acquisition and are therefore not suitable for hydraulic truck-loading cranes, as the acquisition of a overload protection, uie shown, with regard to the price in etuia in the same order of magnitude ranked like the price of a crane itself.

In the case of hydraulic loading cranes, every function, e.g. lifting arm actuation, lip arm actuation and telescopic retraction and extension, has so far been provided with overcurrent or overload valves. This type of load torque limitation does not fully meet the requirements of the UUU, uieil for one Actuation of the telescopic boom e.g. extend, e.g. the overload valve of the lifting cylinder responds to a certain delivery and weight, but the system is not shut down, but the boom slowly lowers overflow through the safety valve.

Furthermore, a shut-off valve has become known that when a certain pressure is exceeded the oil circuit in the crane's lifting cylinder

309827/0141

the pump short-circuits in front of the control valves so that no oil can flow to the control valves With this device, however, bending that reduces the load torque is not always possible, E.g. the telescope can no longer be retracted P and the lifting arm can no longer be raised. This

but is necessary when the lift arm and luffing arm stands above the horizontal through the boom pivot point.

Furthermore bind shut-off valve became known, which are controlled by the pressure of the lifting cylinder and behind the control valve in the supply line to the Each hydraulic cylinder is arranged · These

k valves block e.g. the function of Ausiuippens soie the '

Extension of the telescope when activated by a certain lifting cylinder pressure

Based on the prior art shown It is now the object of the invention to provide an improved device for automatically limiting the load on drive elements actuated by pressure medium to disclose, through which the disadvantages mentioned at the outset are avoided and bBi the insecurity

309827 / 0U1

at maximum load on one of the working elements a supply of pressure medium to another work element in the sense of a load increase prevented.

According to the invention, the object set is thereby achieved solved that to block the control slide in the main control valve black var the same baking valves are arranged, which of one od. Several 3-2 Uegeventile (s) can be acted upon, whereby the 3-2 way valves are controlled magnetically, so that the magnets over one by arm switch and a closed circuit pressure switch, whereby the flow of flow to the Hose lines for the cantilever arms can be influenced in such a way that the supply of the pressure medium (oil) to the drive elements for the lift arm, rocker arm and telescopic arm is prevented if the permissible Resilience is reached or blocks for such work processes, the implementation of a further Loading of the cantilever arms, which are already subjected to the highest permissible loads.

309827 / 0U1

Another feature of the invention can be seen in that the blocking valve has assistance! such as known hydraulic hose lines with is connected to the lift cylinders for the lift arm. The blocking valves are connected to the leveling valve (s) Pressure lines or the like positively connected

Finally it should be mentioned that the blocking valves if several 3-2 directional control valves are veneered, each have two pistons, which diB respective Block the push rod of the main control valve. If only a 3-2 way valve is used, only one of these pistons is required, as the blockage only takes place in one direction in this head.

The following description serves to explain the subject matter according to the invention, of which an exemplary embodiment is shown in the drawings, it shows:

Fig. 1 is a schematic representation of the

Overload shutdown device according to the invention in conjunction with a hydraulic loading crane and

309827 / 0U1

-

2 shows a circuit diagram of the subject matter according to the invention.

Assuming that the pressure in the lift cylinders 22 is characteristic of the load torque and a certain value must not exceed souiieso, so you can take advantage of the pressure, the electric pressure switch 29 to operate · The DC circuit of eg 2k UOIT is now at the Primary position B closed, the arm switches 12, 13, 14 and 15 have a certain closed position depending on the display and angular position of the cantilever arms 19, 20 and 21, so that some parallel circuits are created, each actuating a magnet 36. The 3-2 way valves 6 to 11, which are magnetically actuated on this flex, let the pressure medium, be it pressure oil (e.g. from the lifting cylinders 22 or the main oil circuit) or air (e.g. from the brake air reservoir of the LKbI ¹ s) on one side or on both Sides of the blocking valves 3, k bzui. 5 stream. As a result, the control slide 1 of a specific control function is blocked in one or in both directions of actuation. The Armschalter 12, 13, "\ _t k 15 are disposed in the pivot points between the arms 19, 20 and 21 and to turn at a particular bJinkelstellung.

309827 / 0U1 ~ ¹⁰ ~

- ίο -

The device according to the invention works according to the figure follows:

On a loading crane known per se, arm switches 12, 13, 1 ** and 15 are arranged in the articulation points between the jib arms 19, 20 and 21, which can be switched over when the jib arms 19, 20 and one another are in a certain position or the other circuit closed · The primary switch is in dB «Druckachalter 29 · The characteristic pressure of the lifting cylinder 22 actuates this pressure switch 29, so that current, depending on which circuit is closed by the arm switches 12 to 15, to the Solenoid 36 of the directional control valves 6 to 11, can flow. The directional control valves 6 to 11 are designed according to the invention as 3-2 directional control valves with magnetic actuation. In the non-actuated state, the connection to the blocking valve 3 or k or 5 serves as a leakage oil line. When one of the directional control valves is actuated, the pressure medium flows; in the exemplary embodiment, this is the one under pressure

309827 / 0U1 " ^ "

216462E

Oil from the HubzyHinder 22, via the directional control valves 6 to 11 into one or the other side of one of the blocking valves 3 to 5. According to the invention, the blocking valves 3 to 5 are designed in such a way that they prevent the control of a specific function. This is done in that a mechanical connection between the control rod of the control valve 2 and the blocking valve 3 bzuu h bzui. 5 exists. The mechanical connection can be the control slide 1 itself or a control rod with a lever transmission. The electrical leads, if necessary, are shown in the figure by thin dashed lines.

In FIG. 2, a schematic circuit diagram provides information about the functional sequence of the entire device according to the invention. The characteristic pressure of the Hubzyländers 22 acts on the pressure switch 29. By means of a spring and adjusting screw 30 the same can be set so that it switches the switch 29 from position A to position B at a certain pressure. At this moment the current of a direct current battery of e.g. 2h \ falt is closed. The circuit is further switched in the arm switch 12 to the position Cbder D. 309827 / 0U1

- 12 -

2164028

Circuit C means: The column 31 and the lifting arm 19 form an acute angle. The position D means that the lifting arm 19 ueitergeschbiernkt above the horizontal uird. The critical switching point is thus at the right angle between column 31 and Lift arm 19. Another arm switch 13 between the lift arm 19 and the üJipparm 20 causes in position E, that the current can flow once to the directional control valve 6 or to the directional control valve 7. In position F both Control valves S, 7 connected in parallel. The arm switch 13 is attached for the reason that by the possibility of luffing the Uipparms 20 the l / receives for the blocking of the lifting arm 19 9n one or the other direction are not so easy to survey. The arm switch 13 switches the Circuits in parallel if the rocker arm 20 more than 20 lies under the extended position of both arms 19, 20. As a starting point one would have without further ado can choose another angle than mentioned above. The angle depends on the construction and should if possible be chosen so that there are no major differences between the load torque when the

309827 / 0U1

- 13 -

Display and the display inclined at 20 °, for example. If the LJipparm 2Q now comes below 20 °, the entire lifting arm actuation, as already mentioned, is blocked. To reduce the overload torque, only the ttiipparmbetetrieb or telescopic actuation is available.If one of the magnets 36 or both magnets 36 of the directional control valve is attracted, the directional valve is in position g.In this position, oil flows from port 32 to port 33 via the known Pressure line into connection 3k of blocking valve 3. There the calf 26 is shifted to the right so that the piston disc 35, which is positively connected to the control slide 1 (control rod) of the control valve 2, cannot be pulled to the left, i.e. lifting of the lifting arm 19 is blocked. In the zero position of the directional control valve 6, oil can flow back from the connection point 3k via the connection point 33 to the connection point 37 into the tank 38. What is stated for the directional control valve 6 also applies to the directional control valve 7 when the arm switch 12 is in the D position. In this position, the lift arm function

- 11 »309827 / 0U1

Lowering blocked. Simultaneously with the one-time-old of the pressure switch 29 is the circuit for the directional control valves β bztj. 9 released, depending on whether the arm switch 14 is in the H or I position. The arm switch 14 is located in the arm system at the crane tip at the pivot point of the load handling device, see 1. The position H is given when the load direction forms an angle of 90 to 270 ° with the bJipparmrichtung, t / on 270 to + 90 ° results position I. The switching on of the directional control valves 8 and 9 corresponds to the directional control valves 6 and 7. What has been said also applies to the blocking of the telescopic slide-out piece and the actuation of the Blocking valve 5. The decision whether the directional control valve 10 or 11 is operated depends on the Arm switch 15, which is in the same place as the arm switch 14 can be arranged, which then switches to position J when the load direction with the rocker arm 20 is at an angle of 1BQ to 360 ° forms. The position K is switched when the rocker arm 20 and the load direction have a position point from 0 to 180 ° to each other. According to the circuit diagram shown in Fig. 2, can

- 15 -309827 / 0U1

2164828

further directional control valves, blocking valves and arm switches can be arranged and switched. The decisive factor here is that ωχe the cantilever arm system is multi-part. If the arm system has more than two outriggers, additional arm switches, which can be operated at the same time, have to be switched on according to the lifting arm function. These arm switches correspond to the arm switch 13, which simultaneously causes the corresponding directional control valve 6 to 11 to be blocked in both directions.

There is also the possibility of using the overload cut-off device on only one of the 3-2 directional control valves (6 to 11) if, for example, arm switches (12, 13, 14 and 15) are not required Arm switch can be omitted if work is only carried out in certain areas of the arm positions, ωο a monitoring of the load disconnection of subordinate Nature is. When using a single 3-2 way valve, the blocking valves 3, 4 and 5 bon applied to this single directional valve Since in this case a blockage only takes place in one direction, can do without the piston 27 in the blocking valve 3, 4 and 5 uiBrden

- 16 309827 / OUT-

Claims (1)

Claims j 1st overload cut-off device for consecutive ^ -Coupled hydraulic lifting mechanisms, especially in hydraulic loading cranes, characterized in that for w Blocking of the control spool (1) in the main control valve block (2) in front of the same (2) blocking valves (3, k, 5) are arranged, which can be acted upon by one or more iilegeventile (s) (6 or 6 to 11), the directional control valves (6 to 11) being magnetic be controlled in such a way that the magnets (36) are actuated by an arm switch (12, 13, 14 or 15) and a pressure switch (29) closed circuit, whereby the flow of flow to the hose lines (16, 17, 18) for the extension arms (19, 20, 21) can be influenced in such a way that the supply of the pressure medium (Ul) to the drive elements for the Lift arm (19), lilipparm (2) and telescopic arm (21) are interrupted is when the permissible load capacity is reached or the inflow for such work processes blocks, the implementation of which a further load capacity of the already highest permissible burdened Extension arms (19, 20, 21) result in .. 309827 / 0U1 " ¹⁷ " 2. Overload shutdown device according to claim 1, characterized in that the Blocking valve (3) via auxiliary services, such as known hydraulic hose lines with the lifting cylinders (22) for the lifting arm (19) is connected. 3. Overload shutdown device according to claims 1 and 2, characterized in that the Blackier valves (3, k and 5) with the directional control valves (6 to 11) via pressure lines (23, 2h and 25) ad. the like are connected. k. Overload cut-off device according to Claims 1 to 3, characterized in that the blocking valves (3, k and 5) each have pistons (26 and 27), some of which block the respective push rod (26) of the main control block valve (2). 5. Overload shutdown device according to claims 1 to 3, characterized in that when a single 3-2 way valve (6 to 11) is arranged, the blocking valves (3, k, 5) have a piston (26). 309 8 27 / 0U 1