This application claims priority to German Patent Application No. 10 2019 202 647.8 filed Feb. 27, 2019, the disclosure of which is hereby incorporated by reference in its entirety.
The invention relates to a loading arm device which is in particular suited for loading fluids.
Such devices, as described e.g. in EP 2 757 967, comprise a main arm and an articulated external arm which is connected with the main arm. The main arm is pivotally supported by a base element such as a vertical column. The external arm is pivotally connected with a front end of the main arm, and a counter-weight arm is provided e.g. at the opposite rear part of the main arm (rear arm). The outer arm is coupled with the counter-weight arm via a coupling element such that the two arms are always parallel to each other when the arms are moved. A corresponding coupling may be realized using coupling rods, coupling cables or the like, as known e.g. from EP 2 757 067.
Using such loading arms, e.g. fluids are filled into transport tanks provided on ships. Since these may possibly be toxic or flammable fluids, fluid leakage must be prevented. There is a serious risk that a ship drifts off during the filling operation, causing the loading arm or the ship-side pipe to be damaged or torn off. It is mandatory to secure that fluid leakage due to damage is avoided. This is achieved by closing one valve or two valves within short time, as soon as there is a risk of the loading arm being damaged or even torn off, the valves typically being located at the free end of the external arm. At the same time or immediately after the closing of the valves a separating coupling is separated. This is realized by providing a switching means. A corresponding switching means comprises two switching elements such as e.g. a switching plate and a proximity switch. Typically, one of the two switching elements (e.g. the switching plate) is arranged on the main arm in that region in which the main arm is connected with the counter-weight arm. The second switching element (e.g. the proximity switch) is connected with the counter-weight arm. A deflection of the arm causes the two switching elements to move towards each other, when reaching a predetermined maximum scissors angle between the external arm and the main arm, the switching plate is switched by the proximity switch. This causes the valves to close and the coupling to be opened.
At the maximum scissors angle, great forces and moments occur in the external arm and in the main arm, in particular in an upper position of the arms. Thus, the entire loading arm device has to be of an extremely solid design resulting in great weight both of the individual arms and the counter-weight provided at the counter-weight arm. In a lower position of the external arm which occurs e.g. at low water level, the forces and moments occurring are significantly smaller so that the above problem does not exist in this case.
However, it is not readily possible to define different maximum scissors angles for different positions of the external arm, using electronic components such as a rotary encoder. For reasons of safety, the relevant regulations (e.g. DIN EN ISO 16904, OCIMF) or customer specifications stipulate or at least recommend that such safety-relevant switching means have to be proximity switches, possibly with SIL rating or 2oo3 voting.
It is an object of the invention to provide a loading arm device in which the maximum forces and moments occurring are reduced.
The object is achieved according to the invention with a loading arm device with the features of claim 1.
The loading arm device of the invention is suited in particular for loading fluids into tanks provided on ships. The loading arm device has a main arm pivotally supported by a base element. The base element may in particular be a stationary element e.g. a support frame, a vertical column or the like. An external arm is pivotally connected with a front end of the main arm. At its free end, the main arm preferably has a coupling for connection with a fluid pipe e.g. provided by a ship.
A counter-weight arm is connected with e.g. the rear part of the main arm (rear arm). The former carries a counter-weight or is configured such that it serves as a counter-weight. Further, the loading arm device comprises a coupling element coupling the counter-weight arm with the external arm such that the counter-weight arm and the external arm are parallel to each other in different swiveled positions. The coupling element specifically guarantees that the counter-weight arm is parallel to the external arm in any optional position of the external arm. Moreover, the loading arm device has a switching means with at least two switching elements. The two switching elements may be rotated relative to each other to trigger a switching operation at a maximum scissors angle, i.e. a maximum angle between the main arm and the external arm.
According to the invention one of the switching elements is rigidly connected with the counter-weight arm or the external arm. The other or second switching element is rotatably connected with the main arm. Due to this rotatable connection of one of the two switching elements with the main arm, it is possible that the switching means triggers at different maximum scissors angles which depend on the position of the main arm. For example, by means of the switching means of the invention, it is possible to allow a larger scissors angle for triggering a switching operation at a low position than at an upper of high position of the main arm. As a consequence, the switching operation is triggered earlier at an upper position or at higher positions that at a lower position. This has the advantage that the forces and moments occurring are smaller at higher positions and in particular at the upper position that in prior art, since a smaller maximum scissors angle exists.
In a particularly preferred embodiment of the invention the rotatable switching element is connected with the base element or a stationary support element via an actuation means. Thus, due to the actuation means, swiveling the main arm causes a rotation of the rotatable switching element relative to the main arm. By swiveling the main arm, the position of the main arm and the pivotable switching element changes with respect to each other. It is further preferred that the actuation means is an actuation linkage.
The main arm is preferably connected with the base element via a hinge. It is further preferred that the main arm has a rear arm arranged between the hinge and the counter-weight arm, as well as an internal arm arranged between the hinge and the external arm. The rear arm and the internal arm are preferably integral or at least rigidly connected with each other.
It is further possible that the internal arm and the rear arm are not one part with a common fulcrum, but each has a fulcrum of its own, wherein these are arranged one above the other. With such a design of a loading arm, a parallel linkage causes the internal arm and the rear arm to rotate simultaneously and in the same direction. Thus, it is possible to quasi reposition the rear arm upward so as to be able to realize an extremely short vertical column in this manner.
Preferably, the rotatable switching element is connected with the rear arm and the fixed switching element is connected with the counter-weight arm. As an alternative, the rotatable switching element may also be connected with the internal arm, in case of which the fixed switching element is connected with the external arm.
Preferably, one of the switching elements is a switching plate and the other switching element is a proximity switch.
It is further preferred that the coupling element is a coupling linkage and/or coupling cables.
Further, it is preferred and possible with the loading arm device of the invention to define an initial position of two switching elements relative to each other. In particular this is the maximum distance between the two switching elements. Thereby, a maximum scissors angle is set, wherein the maximum scissors angle is the largest at the lowest position and decreases upwards to the uppermost position. Setting the initial position may be effected e.g. by setting the position of the rotatable switching elements by means of the actuation means.
The loading arm device of the invention further has the advantage that, due to the smaller forces and moments occurring, the external arm and the main arm may be designed to be lighter. As a result, a lighter counter weight may be provided. This significantly reduces the costs of the loading arm device.
The invention will be described in more detail below with reference to a preferred embodiment and to the accompanying drawings.
In the Figures:
The loading arm device of both the prior art (
A hinge 22 is connected with a front end 20 of the main arm or the internal arm. An external arm 24 is connected with the hinge 22. Closing valves (not illustrated) with a separating coupling and a connecting coupling for connecting the external arm with a pipe system provided e.g. on a ship can be provided at a free end of the external arm 24, respectively.
A counter-weight arm 30 is connected with a rear part of the main arm 18, the counter-weight arm carrying a counter-weight 32 in the embodiment illustrated. In the Figures a rectangular line defines a working range 34 within which the free end 26 of the external arm 24 is moved during conventional use. A curved line 36 illustrates the maximum position of the outer end 26 at a maximum scissors angle a (
In loading arm devices according to prior art (
According to the preferred embodiment of the invention as illustrated in
At a lower inner position of the external arm 24 (
At an intermediate inner position of the external arm, as illustrated in
As illustrated in
Number | Date | Country | Kind |
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10 2019 202 647.8 | Feb 2019 | DE | national |