Patent Application
20050133773
The invention relates to a drawworks of the type corresponding to the preamble of claim 1.
Such drawworks serve to lower and withdraw a load, in particular a drilling device or a borehole plugging device, for example from a floating platform onto the sea bottom or into or onto a borehole. They have a rotatably mounted winding drum, to which a flexible draw means is fastened, which is usually designed as steel cable and can be wound up or unwound by rotary drive of the winding drum.
At least one rotary drive device is provided for the rotary drive of the drum. This rotary drive device regularly comprises an electric motor. However, it is likewise possible to use a hydraulic or pneumatic drive instead of a direct-current motor.
To brake the winding drum during the lowering of the load and to hold the load above the bottom, such drawworks have a brake device which comprises a mechanically acting brake arrangement. To relieve this mechanically acting brake arrangement, further brake arrangements which do not act mechanically, for example eddy-current brake arrangements, may also be provided.
In practice, the drawworks are adapted in their construction to the maximum hoisting capacity to be expected, which is determined by the intended use of the drawworks. Said hoisting capacity, by definition, is specified for the first cable layer on the winding drum. For further winding layers, i.e. during further winding-up of the cable onto the winding drum, the maximum hoisting capacity decreases due to the larger lever associated therewith, under which the load acts on the winding drum.
For safety, the cable is dimensioned in such a way that its breaking load corresponds to at least twice the hoisting load of the drawworks. The superstructures via which the cable is deflected—for example a mast—are designed for 1.8 times the hoisting load. In order to avoid a situation, caused by actuation of the brake device, in which forces can be exerted on the superstructures or the cable which are greater than the breaking load of these components, the brake device is conceived in such a way that the maximum load to be held corresponds to 1.5 to 1.6 times the hoisting load.
In the past, incidents have repeatedly occurred in which an unwinding operation could not be stopped or could not be stopped in good time by means of the brake device. A possible cause for a series of such incidents could have been that loads were held above the bottom close to the maximum hoisting load with multiple cable layer on the winding drum, which has finally led to overloading of the brake device.
The object of the invention is therefore to improve the operational safety of such drawworks.
This object is achieved by the invention reproduced in claim 1.
Owing to the fact that, according to the invention, an emergency brake device is provided for producing an additional braking force, the brake devices used hitherto, which—as described above—offer protection against overloading of other components and ensure trouble-free operation in the vast majority of applications, can continue to be used. The additional emergency brake device now enables an additional braking force to be applied if required, i.e. if the braking power is momentarily inadequate. Since the emergency brake devices are devices which are provided in addition to the brake device, and the latter is not simply dimensioned to be larger, the emergency brake devices are only activated when they are actually required. Braking of the winding drum is therefore even possible in the event of a total failure of the brake device.
In a first preferred embodiment of the drawworks according to the invention, the brake arrangement has at least one brake shoe acting on a rotary part and a device for applying a braking force to the at least one brake shoe, the emergency brake arrangement being designed in such a way that an additional device for optionally exerting an additional braking force on the rotary part is provided. If the braking power which can be achieved with the brake arrangement in normal operation is no longer sufficient, additional braking power can be actively produced by actuating the additional device.
The device for applying a braking force to the at least one brake shoe preferably comprises a spring arrangement applying the braking force to the at least one brake shoe. To control the braking force exerted on the brake shoe, the device comprises an arrangement which acts in the opposite direction to the spring arrangement and is intended for controlling the braking force exerted on the brake shoe. This measure ensures that, if the hydraulic device fails, the brake shoes are pressed against the brake disk with the maximum force, so that the maximum braking power is produced.
The additional device is then preferably designed in such a way that it comprises an arrangement for displacing the seat absorbing the reaction forces of the spring arrangement. When the additional device is actuated, the preloading of the spring arrangement is therefore increased, which leads to an increase in the braking force acting on the at least one brake shoe and thus to an increase in the braking power.
The additional device is preferably designed as a device which can be actuated hydraulically.
In a further preferred embodiment of the drawworks according to the invention, the emergency brake arrangement comprises an additional brake device which can be engaged alternatively to the brake arrangement.
If the brake arrangement and emergency brake arrangement are designed in such a way that in each case at least one hundred percent of the maximum braking power required can be achieved with them, the emergency brake arrangement can completely replace the brake arrangement, so that emergency operation of the drawworks is possible even in the event of complete failure of the brake arrangement.
The construction of the emergency brake arrangement can at least essentially correspond to that of the main brake arrangement.
If the drawworks comprises at least one gearbox coupled on the input side to a drive motor and interacting on the output side with a summation gear, it is possible to arrange the emergency brake arrangement on the input side and/or on the output side of the gearbox.
The emergency brake arrangement can be engaged manually.
Especially preferred, however, is an embodiment in which a control device is provided which compares the respective braking-power setpoint with a parameter characteristic of the braking-power actual value achieved by the main brake arrangement and, in the event of a differential value of braking setpoint—braking actual value >0, activates the emergency brake device so that the differential value corresponds approximately to 0, the maximum total braking power preferably being ≦130% of the braking-power setpoint. In this especially preferred embodiment, if the braking power achieved with the main brake arrangement decreases below the setpoint, the emergency brake arrangement is activated via the control device for producing the additional braking power required. Limiting the total braking power to a maximum of 130% of the setpoint avoids a situation in which forces exerted on the components of the drawworks or on other components by initiating the braking power reach values above the breaking loads of these components, thereby avoiding the risk of damage due to the initiation of excessive braking power.
In a further embodiment of the drawworks according to the invention, the emergency braking arrangement is formed by a feeding device for the controlled or regulated lowering, holding or withdrawal of the load, to be precise by virtue of the fact that the lowering device has a capacity suitable for braking and holding the maximum hoisting capacity of the drawworks.
The feeding device preferably comprises an electrically, hydraulically or pneumatically driven motor, which also serves to apply the emergency braking power. Furthermore, if the feeding device comprises a gearbox, to which the motor is coupled, the motor can be coupled to the gearbox via an additional gear shaft. However, it is likewise possible to couple the motor to the input shaft of the gearbox for a main drive motor for the drawworks.
Exemplary embodiments of the invention are shown in the drawing, in which:
The drawworks designated overall by 100 in
A brake disk 9 is arranged in a rotationally fixed manner on that region of the drum shaft 3 which is located on the right of the drum 2 in
To assist the brake arrangement 10 during the braking of an unwinding operation, an eddy-current brake 13 connected to the drum shaft 3 is provided on the other side of the brake arrangement 10 as viewed from the drum 2.
The drive unit 14 of the drawworks 100 for driving the drum 2 is arranged on the left-hand side of the drum 2 according to
On the output side, the drive motors 15, 16 on the one hand and 17 on the other hand are operatively connected to gearboxes 19, 20 which are coupled on the output side to a summation gear 21 which transmits the drive moment provided by the drive motors 15, 16, 17 to the drum shaft 3.
In the drawworks 100, the brake caliper arrangements 11, 12 are configured in the manner which can be seen schematically from
Furthermore, each spring arrangement comprises a further device 26, 27 which can be actuated hydraulically and with which the spring preloading can be increased, which, during actuation, leads to the increase in the braking force with which the respective brake shoe is pressed against the brake disk and thus leads to an increase in the braking power. To this end, in the exemplary embodiment shown in
The emergency brake device formed by the measures described above is actuated by an emergency switch 30 which can be actuated manually and via which electromagnetically actuated hydraulic valves 31, 32 are activated, which upon actuation direct hydraulic fluid from a pressure reservoir 33 via lines 34 to the devices 26, 27.
The configuration described with reference to
The further exemplary embodiment, shown in
In the drawworks 200, the shafts of the drive motors 116, 117 are connected to disk brake arrangements 35, 36, with which the respectively associated shaft can be braked. The disk brake arrangements 35, 36 together form an emergency brake device for producing an additional braking force.
The disk brake arrangements 35, 36 are actuated in the manner which can be seen from
In the further exemplary embodiment shown in a cutaway view in
The exemplary embodiment of a drawworks shown in
List of Designations
| Number | Date | Country | Kind |
|---|---|---|---|
| 102 08 370.3 | Feb 2002 | DE | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP03/01665 | 2/19/2003 | WO |
