SU431735A1 - Contactless device for limiting crane hoisting capacity - Google Patents

Description

The invention relates to devices that ensure the safety of the cranes, and is intended to protect the latter from overload.

Known contactless load limiters cranes, containing load sensors and boom, made in the form of a screen located in the gap between unrelated common magnetic core armored cores, in which are mounted the primary coils included in the sinusoidal oscillator circuit, and the secondary coils included in the differential scheme and associated with a phase-sensitive detector, the signals from which, independently of one another, enter the comparison circuit associated with the actuators .

However, the known limiters are complex in design and do not provide the required accuracy.

In order to simplify the limiter and increase its reliability, the load and departure sensors are made combined with common armored cores that give out the output signal, straight

2

proportional to the moment applied to the crane arm.

FIG. 1 shows the proposed 5 load limiter, FIG. 2 - electrical circuit.

The contactless crane load limiter contains a combined load and departure sensor with common armored cores and a comparison circuit.

The sensor consists of an elastic element 1, the movement of parts 2 and 3 of which serves as a measure of the applied load, from Ki. On the part 2 of the elastic element by means of the bracket 4, a screen is fixed, consisting of two parts 5, entering into the gap between the cores 6 and 7, carrying the primary coils 2θ У 4 and V and the secondary coils У ^ and У4. The windings of the primary coils U ₁ and U ^ are connected in series to the collector circuit of the transistor T <, on which an autogenerator is assembled according to a three-point-capacitance circuit.

The secondary windings of the coils V and V4 are also connected in series, but loaded with a phase-sensitive circuit (diodes D ₄ and D ?, capacitors C <and C ^, resistors and K2) so that

3

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four

its output appears straightened and smoothed voltage, equal to the difference of the signal sv ^ yv on the secondary windings. Differential switching scheme allows to increase the accuracy and double the sensitivity. Cores 6 and 7 are mounted on ⁵

bracket 8, mounted on the part \ 3 of the elastic element 1. Each of the parts 5 of the screen mounted on curved guides 9 so that the center of rotation of the screens lies n ^ the intersection of their working edges with a line connecting the centers of the cores.

Under this condition, rectilinear movement of the screens relative to the cores due to the deformation of the elastic element and rotation of the screens do not cause mutual influence. The synchronous rotation of parts of the screen takes place by means of a gear 10, driven by a roller 11, which is connected with a boom reach meter.

The relative displacement of the screen and the cores, and hence the output signal, is determined by the combination of the influence of the load and the outflow. To match the output signal with the signal of the comparison circuit, a simple T2 emitter follower circuit is used.

The load limiter works as follows. ¹³

The output signal from the common transducer for both sensors is fed to the input of the reference element, where it is compared with a constant signal set by the divider formed by variable resistors

- Kb.

In the absence of a load on a hook or when a crane is operating with a load that is valid for a given departure, comparison element ¹ generates a signal arriving at the output relay, which is then in a closed state.

When a crane operates with a cargo that is unacceptable for a given departure, an emergency signal is sent to the output relay at which the latter is triggered, including an audible signal and breaking the electric circuit of the crane actuators.

Claims (1)

Claim A contactless lifting capacity limiter for cranes containing load and boom overload sensors, made in the form of a screen located in the gap between unrelated common magnetic conductor armor cores in which the primary coils included in the sinusoidal oscillator circuit, and the secondary coils mounted differential circuit and associated with a phase-sensitive detector, the signals from which, independently of one another, enter the comparison circuit associated with the actuators, Due to the fact that, in order to simplify the limiter and increase its reliability, the load and departure sensors are made combined with common armored cores, producing an output signal directly proportional to the moment applied to the crane boom. 431735