DK174548B1 - Moment compensator for the reduction of hull swinging in a ship, along with a procedure and an internal combustion engine for this - Google Patents

Abstract

An internal combustion engine (2) is mounted in an extended ship's hull (1), which has a vertical longitudinal centre plane. The rotating and back and forth action of the moving masses in the engine can produce a 1. type exterior moment (M1H), which can effect swings in the hull. A moment compensator (3) for this 1. type exterior moment is mounted within the hull on its vertical longitudinal centre plane, and at a considerable distance from the engine. The compensator (3) has a mainly vertical swivel-feature axle (7), which carries an eccentrically fixed swing mass (6), which, from a pinion influencing the axle (22), rotates in synchrony, and in a predetermined phase, in relation to the engine's 1. type exterior moment so that this is resisted by the centrifugal force (F1C), which works at a distance (R) from the nearest juncture (4) for the actual form of swinging in the hull.<IMAGE>

Description

in DK 174548 B1

BACKGROUND OF THE INVENTION 1. Field of the Invention This invention relates to torque compensator for reducing hull oscillations in a ship with an elongated hull with a vertical longitudinal center plane and with a large two-stroke slow propulsion engine, the rotary and reciprocating masses being able to produce a first-order external torque which affects the hull and can set this in oscillations where the torque compensator for reducing the first-order external torque is mounted on the hull at its longitudinal vertical center plane at a substantial distance from the engine, and where the compensator has a pivot mass which can be rotated synchronously by a drive. and in a predetermined phase relative to the outer order of the engine.

The hull of the ship with the engine mounted therein forms a mass-elastic system in which the hull has various oscillatory shapes with associated eigenfrequencies. The rotating and reciprocating masses in the engine produce internal forces in the engine as well as external forces and torques that affect the hull. The external forces and 20 moments can be described by means of Fourier analysis as a sum of sine functions with different amplitudes, phase angles and periods. As the masses of the motor rotate and move back and forth at a frequency corresponding to the engine rpm, the frequencies of the 25 Fourier divided sine functions correspond to the full multiples of the engine's current rpm. The sine function, also called the harmonic component, with a frequency corresponding to the engine's rotational frequency is called the 1st order component, while the component with a frequency 30 twice the motor frequency is called the 2nd order component, etc. The external moments can thus be divided into components called 1st order momentum, 2nd order momentum etc.

The hull shape of the lowest eigenfrequency 35 has two nodes, the second lowest eigenfrequency three 2 nodes, etc. These oscillation shapes are often referred to as the 2-node oscillation shape, the 3-node oscillation shape, etc. structure around the vertical, longitudinal center plane of the hull, usually only significant global hull swings occur in the horizontal and vertical directions, ie. oscillations which extend the hull in the horizontal plane and in the vertical plane. The external torque of the motor rotates at 10 rpm, but since it produces only horizontal and vertical hull oscillations, it is usual to dissolve the external forces and torque of the motor into horizontal and vertical components and investigate how these affect the horizontal and vertical 15 hull vibrations.

If the frequency of one of the external forces or the components of the coincides with the frequency of one of the modes of oscillation of the hull, a so-called resonance oscillation occurs, where the external forces or 20 moments can supply a great deal of energy to the hull oscillation in question, which can thereby be more powerful than acceptable.

The article "Interaction between hull and motor" from the Norwegian journal "Skipsteknikk", no. 1, 1963 25 describes how free forces and torques from the motor can induce hull vibrations and that the hull vibrations can be removed by changing the frequency conditions for either engine or ship or by mounting a compensator with a rotating swing weight on the hull of 30 at a place where the hull swings have high amplitude.

As mentioned above, the invention relates to the oscillations caused by the outer torque of the first order motor. For 4-cylinder engines, it is known that the first-order external torque can resonate with the hull's 2- or 3-35-node pivotal shape. In this case, the vertical outer torque can normally cause vertical oscillations in the hull, and it is known to remedy this problem by mounting two sets of additional counterweights such that on the engine crankshaft, the size of the 5 vertical The first order's external torque decreases while the '1st order's outer torque increases. In the rare cases where the first-order outer torque produces both vertical and horizontal oscillations in the hull, in the prior art a separate torque compensator in the form of two counter-rotating masses is applied, respectively, to a sprocket fixed to the crankshaft, which through a chain drives the engine's steering shaft, and on a chain tensioner serving wheel mounted on the end of the engine. These two masses are arranged in relation to each other such that the centrifugal force produced by the sprockets in the masses produces a resultant horizontal compensating force which varies in size and direction during a motor rotation.

The known counterweights and the separate compensator 20 mounted on the sprockets are described in more detail in Danish Patent Application No. 223/83.

The use of the separate compensator in the form of weights mounted on the sprockets involves several disadvantages.

First, with these weights, only a relatively limited reduction of the first-order external torque can be achieved, partly because the masses must be relatively small, and partly because they are located at the end of the motor, which limits the distance between the compensating horizontal force and the the closest junction for the horizontal pivot of the hull 30, and secondly, engines which do not have a sprocket-guided steering shaft can be conceived.

In the latter case, it will be very costly to place separate sprockets on the engine solely for the purpose of reducing the 1st order external torque.

4 DK 174548 B1

A number of different compensators are known for reducing the second-order external torque of the engine. Some of these compensators are separate units for mounting in, for example, the ship's steering gear compartment, which in relation to 5 of the weights mounted on the engine increases the distance between the compensator and the node in the current oscillation form. The greater distance allows a greater compensating torque to be produced for a particular compensating force. These known second-order torque compensators all produce a varying vertical force and are made up of two pivot weights which are counter-rotating about a horizontal axis. The known second-order torque compensators are relatively complicated in design and suffer from the disadvantage of being difficult to start and synchronize with the engine speed. In order to produce a sufficiently large compensating force, the counter-rotating swing weights must have a considerable mass, and therefore great moments must be used to lift the weights during start-up. To solve this problem, several methods have been developed to put the masses into oscillations with ever-greater fluctuations until the masses can be rotated a full lap and slowly set up at speed and synchronized with the engine. This requires complicated and costly control systems, and a total of 25 in the known second-order torque compensators are so expensive that they are used only when absolutely necessary.

Since the centrifugal force of a rotating mass depends on the square of the rotational speed, the 30 rotating mass of a 1st order torque compensator must be four times the mass of a 2nd order compensator to produce the same compensating force.

A torque compensator of the kind mentioned above is known from Danish patent 149 479, in which a combined 1st and 2nd order torque compensator is driven by a hydraulic fluid supplied to a hydraulic fluid from a pump mounted on the internal combustion engine. The position of the torque compensator at a considerable distance from the motor gives the advantage that a desired compensating torque can be produced by a relatively small pivot mass because it is? compensating force acts at a greater distance from the nearest node of the current hull vibration shape. The pivot masses in this compensator are rotated about horizontal shafts and the hydraulic motor takes out a large 10 power from the internal combustion engine during commissioning. Due to the long hydraulic connections between the pump and the motor, it has proved difficult to obtain sufficiently precise control of the torque compensator, and the drive system is also very expensive, since both pump 15 and motor must be dimensioned for the high starting torque.

The invention has for its object to provide a single designed and effective actuator for reducing the horizontal first-order external torque of a slow-moving internal combustion engine.

To this end, the torque compensator according to the invention is characterized in that the compensator has a substantially vertical, pivotally mounted shaft which carries an eccentrically fixed pivot mass rotating in a substantially horizontal plane.

Since the pivot mass is mounted on a shaft which is rotatable about a substantially vertical axis, the prior art problems of starting the torque compensator are completely avoided since the gravity of the pivot mass acts substantially perpendicular to the rotation plane of the pivot mass 30. The start-up can thus be carried out largely without regard to the influence of gravity, so that the pivot mass can be simply accelerated up to synchronization with the engine speed without any initial reciprocating pivotal movement. This 35 substantially simplifies the control system of the torque compensator 6 DK 174548 B1 and furthermore makes it possible to use an advantageously small drive motor, for example an electric motor.

The torque compensator is also considerably simpler because it is only necessary to use a single 5 pivot mass instead of the two counter-rotating masses known from the second-order torque compensators. The use of only one pivot mass does mean that, in addition to the desired varying horizontal force in the transverse direction of the ship, a varying horizontal force 10 in the longitudinal direction of the ship also arises, but since the torque compensator is mounted on the hull at its longitudinal, vertical center plane it provokes it in the ship's longitudinal pulsating compensatory force does not have any significant moments which can induce oscillations in the hull. The compensating torque phase 15 can be adjusted as needed by adjusting the compensator motion phase relative to the first-order external torque phase. This has the advantage that the compensating torque can be fine-tuned after the commissioning of the ship, thereby compensating for the practically unavoidable inaccuracies in the theoretically performed oscillation calculations.

If, for practical reasons, the compensator must be mounted with substantial vertical separation from the bend neutral axis of the hull, the pulsating force produced by the compensator in the longitudinal direction of the ship may be prevented from providing vertical bending moments by the distance of the first order torque compensator in a preferred embodiment. L in the vertical direction from the bend neutral axis of the hull and in the distance R in the horizontal direction 30 from the junction of the actual oscillation shape of the vertical oscillations of the hull, and that the substantially vertical axis of the compensator forms an angle of tg a - L / R with vertical. Thus, the longitudinal force will pass through or at a short distance past the node so that bending moments do not occur. The vertical axis may conveniently be housed in an upper and a lower rolling bearing where the upper bearing can absorb greater loads than the lower bearing. The dimensioning bearing loads are essentially determined by the centrifugal force's drag in the pivot mass as it rotates, but: since the pivot mass is eccentrically fixed to the shaft, the gravitational force on the pivot mass will impose a bending moment which reduces the bearing load on the lower bearing.

In a preferred embodiment, the first-order torque compensator is combined with a second-order torque compensator comprising two pivot masses, which are eccentrically fixed to at least one horizontally extending shaft, so connected in power ratio in the 2: 1 ratio to the vertical shaft that they two compensators can be driven by a common motor. This embodiment is advantageous when, in addition to a 1st order torque compensator, a 2nd order torque compensator must be used to prevent unwanted vertical 20 oscillations in hull oscillation shapes having, for example, 3, 4 or 5 nodes. The combination of the two compensators into one unit saves space and allows to operate both compensators with a single motor. Since the compensators are operated in a fixed 25 ratio, only a single control system is needed. Thus, if a second-order torque compensator is to be used, it is possible, without much extra cost, to reduce or remove the horizontal 1st-order external torques, 30 It is preferred that the common drive motor is an AC servo motor connected to the horizontal shaft via a two-speed interchangeable planetary gear, and that the rotational speed of the AC servomotor is controlled by a position and rotation speed signal from the internal combustion engine. The AC-35 servomotor is suitable for precise control of the rpm and phase of the compensators 8 phase 17 174848 B1 depending on the rate signals received from the internal combustion engine. The two-stage planetary gear allows a first gear ratio to be used between the motor and the compensator shaft 5 during start-up, so that the servomotor here provides such torque as to avoid a commuting start-up movement. When the oscillating masses of the second-order torque compensator are pulled up to their upper position, the planetary gear can be switched to the second 10 ratio, which is used in acceleration and normal operation of the compensators. The control system for this compensator is thus very simple, since only the planetary gear unit must be switched at startup.

The shafts of the 1st and 2nd order torque compensators may conveniently be interconnected via a bending elastic, torsional rigid coupling which prevents shaft deflections of the 1st order torque compensator from being transmitted to the 2nd order torque compensator shaft.

The clutch also allows you to adjust the phase position of the 1st order torque compensator independently of the 2nd order torque compensator.

The known first-order torque compensators have only been applied to 4-cylinder row motors. An internal combustion engine with a first order torque compensator according to the invention can be designed more freely with respect to the permissible horizontal first order torques, which is a particular advantage of engines with the cylinders arranged in two rows in V-shape. Here, the compensator can be used for engines with larger cylinder numbers, such as 6.8 or 10-cylinder engines. When such a V-motor according to the invention is connected to a torque compensator, it is constructively simple to compensate for the larger first-order external torques which occur in a V-motor.

9 DK 174548 B1

The invention also relates to a method for reducing the first-order external torque from a large slow-moving internal combustion engine to propel a ship with an elongated hull with a vertical longitudinal 5 center plane, where the hull can be inserted into oscillations of the first-order external torque which is caused by rotating and reciprocating masses in the engine, where the maximum vertical component of the 1st order outer torque is reduced to appropriate size by means of pivot masses on engine parts rotating at the same frequency as the crankshaft, thereby increasing the size of the maximum horizontal component at the same time increases. According to the invention, the method is characterized in that by means of a torque compensator, a force is produced which is rotated in a horizontal plane at the same frequency as the crankshaft rotational movement and which is so spaced from the motor that the rotational torque produced by the force decreases or removes the horizontal component of the first-order external torque of the engine.

Although the torque compensator separated from the motor mainly only reduces the horizontal component of the first-order external torque, the vertical component of the external torque is also reduced, so that the entire first-order torque is prevented from causing annoying oscillations 15 in the hull.

An example of an embodiment of the invention will now be described in more detail with reference to the schematic drawing, in which fig. 1 and 2 illustrate a ship hull with a 20 internal combustion engine and a torque compensator according to the invention, seen respectively. FIG. 3 is a vertical section through the torque compensator of FIG. First

In FIG. 1 shows a ship hull 1 with a combustion engine 2 and a torque compensator 3 for reducing the external order of the 1st order. The engine's 1st order outer torque is designated M1H. This torque can produce resonant oscillations for certain 2 or 3-node oscillation shapes at certain rpm. The two 5 nodes of the hull oscillation are marked at 4, and the curve 5 shows on an enlarged scale the deflection shape of the hull in the horizontal plane when a 1st order torque compensator is not used.

The torque compensator 3 produces a rotary force rotating in the horizontal plane whose transverse force component is designated F1C. When the resonance oscillation occurs at engine rpm at or below the motor's Maximum Continuous Rating (MCR) point, the 1st order external torque may be required, especially if the resonance occurs near a continuous operating point of the motor.

The compensator 3 is located at a considerable distance from the motor, preferably in the control room compartment, so that between the compensator and the nearest node 4 there is such a large distance R that a relatively limited force F1C can produce a torque of the same magnitude as M1H, but in the opposite direction. . Since the floor in the control room compartment is often at a small vertical distance from the bending neutral axis of the hull, the longitudinal pulsating forces of the compensator 3 cannot produce significant vertical oscillations in the hull 1. As an alternative to placing the compensator in the control room compartment, the compensator can be placed in a cargo space approximately midway between the two nodes 4, but this will usually require the construction of a supporting platform near the center plane of the hull and near the bend neutral axis, which will distort the installation of the compensator.

If the compensator as shown in FIG. 2 is located at the distance L above the bend neutral axis A of the hull, 35 the compensator can be set at such an angle α in relation to the vertical that the longitudinal force F1C forms a corresponding angle a with the bend neutral axis, whereby the force passes through the node 4. without giving rise to a vertical bending moment.

5 The angle α can be determined from the equation tg a «L / R.

In FIG. 3, the compensator 3 is seen, which both compensates for the first and second order moments. The first-order torque compensator has a pivot mass 6 which may be one-piece or as shown in two pieces 6a, 6b. The pivot mass 6 is eccentrically fixed to a vertical shaft 7 which through an upper and a lower rolling bearing respectively. 8 and 9 are mounted in the upper and lower end cover of the compensator housing, respectively.

10 and 11. The two end covers are held apart by a cylindrical outer wall 12 and the lower end cover 11 15 is fixed by means of bolts not shown to a foundation (not shown) in the ship hull 1.

In order to limit the bending of the shaft 7, it has a large diameter in the shaft section which lies between the bearings 8 and 9. Above the bearing 8, the shaft continues in a reduced diameter section 20 up to a bending elastic and torsional rigid coupling 14 with two end portions 15, 16 which are interconnected through two resilient washers 17, 18 and a tubular spacer 19.

The end portions 15 and 16 can be fixed to the associated 25 resilient washers 17 and 18 in various pivot positions, allowing the shaft position 7TS to be adjusted relative to a shaft pin 20, which is connected to the upper end portion 16, which carries a pointed wheel 21. driven by a motor 22. By adjusting the pivot position of the end portion 15 relative to the shaft 20, the phase of the pivot mass 67 can be adjusted relative to the phase of the outer order of the motor.

A second-order torque compensator 23 is mounted on top of the end cover 10. This compensator has two pivot masses 24a, 24b which are eccentrically fixed on each of the horizontal shafts 25a, 25b, which are mounted in their respective known axes. an associated house respectively. 26a and 26b.

A bracket 27 carries a gear housing 28 which engages the sprocket 21 in engagement with two sprocket wheels 29a, 29b 5 mounted on each shaft 25a, 25b.

The motor 22 stands through a planetary gear 30 in driving communication with the shaft 25b and via the three sprockets in connection with the shafts 7 and 25a. The sprocket 21 has twice as many teeth as the sprocket 29a, 29b, so that the shafts 25 and shaft 7 are connected in the ratio 2: 1. It is seen that the sprocket connection causes the motor 22 to drive the shafts 25a and 25b in opposite directions of rotation.

The drive motor 22 is a so-called standard 15 AC type servo motor, for example manufactured by Siemens and with the type designation 1 FT 5AC servo motor or of the type 1PH 5 / 1PH6 AC servo motor. These motors are suitable for operation of the torque compensator in that they can provide full torque at 0 rpm and because they can be controlled 20 by a simple clock signal. The clock signal can be supplied from the combustion engine regulator or from a crankshaft speed sensor, for example a so-called "optical incremental encoder" with zero encoder.

The planetary gear 30 may be of two-stage design, for example having the ratio of 1: 5 to 1:20 between the driven and the driving shaft. Such a planetary gear is a standard component that can be supplied, for example, by the company alpha-Getriebebau GmbH, Igersheim, Germany.

When the torque compensator is to be started, the planetary gear is first set to give a high gear ratio, for example 1:20, so that the drive motor 22 can exert large torque on the shafts 25a, b during their first half rotation, with the pivot masses 24a, 24b being pulled up against the weight of 35. During the continued rotation 13 of the pivot masses about the shafts 25a, b the planetary gear changes to the lower gear ratio, for example 1: 5, after which the motor 22 accelerates the two torque compensators up to the desired speed of rotation in synchronization with the clock signal from combustion engine.

The pivot masses 24a, b of the second-order torque compensator are affected in their centers of gravity 31 by a centrifugal force F2C / 2, and the masses are so counter-rotating that the horizontal components of the two forces counteract each other to produce a pulsating vertical force with the maximum value F2C. This force produces a vertical torque which counteracts the internal torque of the 2nd order of the internal combustion engine.

The swing mass 6 il. the torque compensator 15 is affected by rotation about the shaft 7 by a horizontal centrifugal force F1C which engages in the center of gravity of gravity 32. In addition, the pivot mass is affected by a gravity F which reduces the load on the lower rolling bearing 9.

20 If only a first-order torque compensator is to be used, the drive motor 22 with an associated single-stage planetary gear can be mounted directly on top of the shaft section 13.

The second-order torque compensator can also be designed with a single pivot mass disposed on one side of the shaft pin 20. This simplifies the compensator, but at the same time gives rise to a pulsating horizontal force.

This solution is only applicable if the horizontal force does not give rise to annoying hull oscillations.

From the above-mentioned Danish patent application it is known to reduce the size of the vertical component of the first order outer torque by appropriately applying pivot masses to motor parts rotating at the same frequency 35 as the crankshaft. In the prior art, this has only been used in cases where the horizontal component of the 1st order outer torque could not induce bothersome hull oscillations. With the first-order torque compensator described above, the increased horizontal component can be reduced or removed completely by the force F1C, and the method according to the invention can therefore also be used in cases where the horizontal component of the first-order external torque can set the hull in oscillations.

Claims (8)

A torque compensator (3) for reducing hull oscillations in a ship with an elongated hull (1) with a vertical longitudinal center plane and with a large two-stroke 5 slow-moving propulsion engine (2) whose rotating and reciprocating masses can produce a 1. the outer torque of the order, which affects the hull and can cause this to fluctuate, where the torque compensator (3) for reducing the first order external torque is mounted on the hull (1) at its longitudinal vertical center plane at a considerable distance from the motor (2), and wherein the compensator has a pivot mass which can be rotated synchronously with and in a predetermined phase relative to the outer torque of the motor by a drive (22), characterized in that the compensator has a substantially vertical, pivotally mounted shaft (7). , which carries an eccentric fixed mass (6) rotating in a substantially horizontal plane. Torque compensator according to claim 1, characterized in that the first-order torque compensator (3) is located in the distance L in the vertical direction from the bend neutral axis of the hull and in the distance R in the horizontal direction from the node (4) for the current oscillation form of the hull vertical. oscillations, and that the substantially vertical shaft of the compensator forms an angle of tg a - L / R with vertical. 3. A torque compensator according to claim 1 or 2, characterized in that the vertical shaft (7) is mounted in an upper and a lower rolling bearing (8,9) and that the upper bearing (8) can withstand greater loads than the lower bearing (9). 30 15 DK 174548 B1 Torque compensator according to one of claims 1-3, characterized in that the first-order torque compensator is combined with a second-order torque compensator (23) comprising two pivot masses (24a, 24b) that are eccentrically fixed to at least one horizontal extending shaft (25a, 25b), which is so transmitted in power ratio in the 2: 1 ratio with the vertical shaft (7) that the two compensators can be driven by a common motor (22). 5. A torque compensator according to claim 4, characterized in that the drive motor is an AC servomotor (22) which is connected to the horizontal shaft (25b) via a two-stage interchangeable planetary gear (30) and that the speed of the AC servomotor is controlled by a position-15 and rotation speed signal from the internal combustion engine (2). 6. A torque compensator according to claim 4 or 5, characterized in that the shafts (7, 25a, 25b) of the first and second order torque compensators are interconnected via a bending elastic torsional rigid coupling. Large two-stroke slow-combustion engine with a torque compensator according to one of the preceding claims, characterized in that the cylinders of the engine (2) are arranged in two rows in V-shape. A method for reducing the first order external torque (M1H) from a large slow-moving internal combustion engine (2) to propel a ship with an elongated hull (1) with a vertical longitudinal center plane where the hull can be swung by the engine 30 1st order outer torque caused by rotating and reciprocating masses in the engine, where the maximum vertical component of the 1st order outer torque is reduced to appropriate size by means of pivot masses on engine parts rotating at the same frequency 33 as the crankshaft, thereby increasing the size of the maximum horizontal component simultaneously, characterized in that a torque compensator (3) produces a force (F1C) rotating in a horizontal plane at the same frequency as the crankshaft rotation, 5 and which is so spaced from the motor (2) that the rotational torque produced by the force decreases or removes the horizontal component of the outer order of the motor torque.