JP3295271B2 - Moment compensator - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a device for compensating for free moments due to inertial forces in a marine piston propulsion engine, in particular a large two-stroke crosshead engine, the device being adapted to extend from the engine in the longitudinal direction of the marine vessel. An unbalanced mass that is adapted to be mounted at a predetermined distance and that can rotate about a horizontal axis; and, after starting the device, the rotational speed and phase angle of the unbalanced mass are determined by the speed and phase angle of the engine. Drive means for rotating the unbalanced mass together with a control device which can be controlled as a function.

[0002]

2. Description of the Prior Art Such devices and their operation are known, for example from EP 0 0010.
No. 73 is disclosed. This patent specification discloses a single unbalanced mass for compensating the first class free moment of the engine, and two unbalanced masses for compensating the first and second class external moments, respectively. A device comprising: Class 2 moment compensation mechanisms are known and compensate for the variable vertical compensation forces generated by two rotating masses rotating in opposite directions about a horizontal axis. The moment compensating mechanism used in connection with the main engine of the ship usually has to produce a large compensating force,
The individual rotating masses must have a fairly large mass so that a sufficiently large compensating force can be produced.
A common feature of known marine compensating mechanisms having an unbalanced mass rotating about a horizontal axis is that starting is difficult. The reason for this is that in order to initiate the rotational movement, the unbalanced mass must be rotated to overcome the large gravity due to the large mass.

[0003] A number of different methods have been developed for rotating the unbalanced mass of known devices. According to one method, the drive means for rotating the unbalanced mass is switched several times until the unbalanced mass is able to make a complete revolution and its speed is slowly increased and synchronized with the engine. Is driven in one direction and the other in a large amplitude pendulum motion. The control device must adjust the time for continuously switching the drive means according to the steadily increasing amplitude of the oscillating motion. Doing this requires complex and expensive controllers that can produce large torques at very low rotational speeds. The above-mentioned European patents use a hydraulic motor which is supplied with hydraulic fluid from a pump mounted on the engine in order to generate a very high starting torque. However, in order to generate a large output, it is necessary to increase the size of the hydraulic motor and the pump, and furthermore, a long fluid piping between the pump and the hydraulic motor is required. It turned out to be difficult to control.

[0004] European Patent Application No. 0 409 462 discloses a device for compensating vibrations generated by an engine. This device has four pairs of concentrically arranged rotors rotating in opposite directions. During operation of the device, the relative angular position of the two rotors in each pair is adjusted between 0 ° and 180 ° to adjust the amount of inertial force generated by the device in response to the magnitude of the undesired vibration. Can be adjusted. The positions of the four rotors are detected by stationary sensors that transmit position signals to a control unit that controls the electric motor for each rotor, and adjusts the magnitude and phase of the compensating force as a function of the operating conditions of the engine. The rotor has a small unbalanced mass and the four electric motors
Rotational movement can occur without the need for special start-up control. In a moment compensator for a ship, the unbalanced mass has a mass that is so large that it is difficult to start the device with an electric motor directly connected to each mass and coordinates the movement of the unbalanced mass. In such a case, it takes some time from when the motor receives the different signal to when the mass body rotates at the new speed.

US Pat. No. 4,289,042 discloses a vibrator having two rotors mounted coaxially about a common axis of rotation, the relative angular position of the rotors being determined by the vibrator. Can be adjusted in order to adjust the stroke, ie, to adjust the magnitude of the vibration generating force.

[0006] Patent FR 1,115,555 discloses a vibrator having two rotors rotatably mounted on a common shaft. One rotor carries a spring-loaded hook, which is
The other rotors can be captured and retained, maintaining the rotors in relative positions to offset any imbalance between the rotors. When the rotor rotates at a sufficiently high speed after starting the vibrator, the hooks are released and the rotor rotates to a second relative position such that the unbalanced mass is at maximum unbalance.

[0007]

SUMMARY OF THE INVENTION It is an object of the present invention to provide a reliable free moment compensator which can be started with a simple control and with a small starting torque, even for very large unbalanced masses. It is.

[0008]

In order to achieve the above object, the device according to the invention is characterized in that an unbalanced mass which can be rotated as a unit is divided into two unbalanced weights in a manner known per se. And each of these weights is mounted eccentrically on a corresponding shaft portion which extends coaxially with the common horizontal axis of rotation and extends within the housing; the shaft portion is hollow and one shaft portion is right-handed. A left-handed inner helical portion on the other shaft portion; a central shaft coaxial with the axis of rotation mounted for longitudinal displacement within the housing; an inner helical portion of the shaft portion. Are engaged with corresponding outer helical teeth on the central shaft; the adjusting device is configured to have a first position where the common center of the mass of the unbalanced weight is located near the axis of rotation; A central shaft can be displaced longitudinally to move the relative position of the unbalanced weight with respect to the axis of rotation during rotational movement between a second position where the center of communication is further away from the axis of rotation. It is becoming.

As the central shaft is displaced longitudinally, the helical teeth rotate the unbalanced weight in the opposite direction about the axis of rotation, thereby displacing the common center of mass radially with respect to the axis of rotation. If the central shaft is not displaced in the direction of the axis of rotation, the central shaft prevents the unbalanced weights from rotating relatively, and these unbalanced weights rotate as a unitary movement. The device according to the invention is compact, the central shaft being able to transmit a very large adjusting force to the two unbalanced weights in a very precise and fast manner of operation. An essential feature of the invention is that the adjustment can be effected by a longitudinal displacement of the central shaft, since a large axially acting adjusting force is obtained in a simple manner, for example by a hydraulic piston / cylinder unit. .

When the device is started, the unbalanced mass can be adjusted so that the center of mass is closer to or coincident with the axis of rotation, and the unbalanced mass is large in the initial rotational movement. The degree of unbalance of the unbalanced mass can be appropriately reduced or zero so that it does not lift against gravity (ie, the moment of inertia is not reduced). In this way, the unbalanced mass can be rotated with a relatively small torque without the need for an initial pendulum movement. Therefore, a small and easily controllable driver, such as an electric motor with an on / off circuit breaker, can be used.

When the unbalanced mass rotates, the center of mass moves away from the axis of rotation. Once the unbalanced mass rotates, the effect of gravity on the eccentric mass is not disturbed. The reason is that gravity produces kinetic energy during the downward swinging movement of the mass corresponding to the energy absorbed during the upward swinging movement of the mass.

Most drive motors generate a larger torque when they are rotated than when they are stationary. However, in the present invention, when the drive motor is started, the center of mass of the unbalanced mass body is centered on the rotation axis. Substantially the effect of bringing it closer or matching the rotation axis can be achieved. Moving the center of mass of the unbalanced mass away from the axis of rotation is
It can start after a relatively small angular rotation, for example 50 ° or 100 °, but preferably the center of mass of the unbalanced mass is at least so as to eliminate as much as possible the effect of gravity on the required torque. During the first half rotation of the unbalanced mass, it is kept on the axis of rotation. Before the center of mass moves away from the axis of rotation, it may be practical to accelerate the unbalanced mass to a speed at which the drive motor produces maximum torque.

The external moment of the propulsion engine, ie, the second-order free moment, is generated by the inertial force on the reciprocating mass of the engine, the magnitude of which depends on the engine speed. The second-order free moment of the engine imparts significant energy to the hull's vibration modes, whose natural frequency is equal to twice the current speed of the engine. For a large two-stroke diesel engine,
For example, at a speed of 90 rpm, the second-order free moments may cause resonance vibrations in the four- or five-node vertical vibration molding of the hull. Relevant hull vibration modes and node locations depend on the loading conditions of the vessel. The vertical compensating force of the compensator generates a compensating moment, the magnitude of which is a function of the horizontal distance from the compensator to the nearest node of hull vibration.

[0014] Under the same load conditions, the distance to the nearest node may change. The reason is that when the speed of the engine changes, the vibration mode of the associated hull changes to a vibration mode with more or fewer nodes. For example, at full load, the engine may generate a five-bar vibration mode, and at partial load (i.e., a lower engine speed), the engine may generate a four-bar vibration mode. Further, as described above, even in the same vibration mode, the position of the node may change according to the distribution and amount of the load on the ship.

The vibration generated by the free moment from the engine (preferably a second-class free moment) can be detected by a vibration sensor associated with the hull of the ship, and based on the detected vibration signal, the computer unit The control signal used for continuous vibration damping adjustment of the distance between the center of mass of the unbalanced mass and the axis of rotation can be determined. Based on the measured current vibration level, when the computer unit determines that a reduction in vibration is desired, the center of mass of the unbalanced mass body depends on whether the compensation force needs to be increased or reduced. Is adjusted further away or closer to the axis of rotation.
In addition to adjusting the rotational speed and phase angle of the compensator as a function of the operation of the engine, the device according to the invention is based on the actually measured vibrations of the hull of the ship, the compensation force being dependent on the current operation of the engine. The size and load condition of the ship can be adjusted. It is not necessary to continuously measure the vibrations and adjust the imbalance of the equipment, but these measurements and adjustments should be made after the load condition of the ship changes and / or when the engine load changes substantially. For a suitable period of time.

Of course, based on empirically obtained numerical data, the center of mass of the unbalanced mass can be automatically adjusted as a function of the load conditions of the ship and the operating conditions of the engine, but in this case the vibration Sensors can be omitted.

The drive means for rotating the unbalanced mass can suitably act on a central shaft, which directly engages each of the two shaft sections.

Adjustable end stops allow for limiting the displacement of the central shaft in view of the adjustment of the magnitude of the unbalance in continuous operation. This adjustment may be performed manually or automatically.

[0019]

1 shows an apparatus for compensating for the free moment generated by the main engine of a ship. The engine may be a large two-stroke crosshead engine that rotates at a maximum continuous rating of 80-120 rpm (revolutions per minute). At low speeds, the free moment generated by the engine becomes a low-frequency moment, and there is a danger of generating resonance vibration with vertical vibration in the hull of the ship,
The need to use a moment compensator arises.

The moment compensator is in place on the hull (eg, the steering gear room, which typically provides an effective long distance to the nearest node in the hull's vibration mode).
Housing 1 bolted or welded to seat located at
02. The first unbalanced weight 104 and the second unbalanced weight 110 are corresponding shaft portions 210, 20 coaxially supported by bearings 203 in the housing 102.
2, the first unbalanced weight is rotatable about an axis of rotation substantially perpendicular to the longitudinal vertical centerline of the vessel.

The first and second unbalanced weights cooperate to form an unbalanced mass which is connected via a chain or synchronous transmission belt 114 to a gear 115 on one pivot.
, Which can be rotated in a common motion about a rotation axis. As the unbalanced mass rotates in synchronization with the engine, the common center of the mass is such that at the current speed of the unbalanced mass, the centrifugal force acting on the center of the mass produces the desired compensating moment. It is separated from the rotation axis by a distance that is large. If the device is used to compensate for a first class free moment from the engine, the unbalanced mass will rotate at the same speed as the engine and use the device to compensate for the second class free moment, etc. In that case, the unbalanced mass rotates at twice the speed of the main engine.

A control device, such as an electronic computer unit, controls the speed and phase angle of the unbalanced mass in synchronization with the speed and phase angle of the main engine. The control device is a motor controller for the drive motor via a wire (eg, a control circuit if the drive motor is an electric motor)
Connected to. The controller receives at least information about the rotational movement of the unbalanced mass from the zero-pulse transmitter 119, which transmits a signal via wire 120 to the controller each time a small actuation means 121 passes the transmitter. What to send.

The signal from the zero-pulse transmitter 119 is calculated by taking into account the phase correction of the center of mass of the unbalanced mass in relation to the operating means 121 and the zero-pulse transmitter mounted on the engine. Is used to determine the phase angle of The phase correction can be adjusted manually using an adjustment member of the control device. By counting the number of signals from the zero pulse transmitter 119 during a given time period, the controller can determine the current rotational speed of the unbalanced mass.

If a more sensitive measurement of the velocity of the unbalanced mass is desired, the controller can be connected to an impulse generator. The impulse generator generates a signal when the unbalanced mass swings a part of one rotation.
Various impulse generators used for this purpose are known, for example, the so-called Optical Incremental Encoder (Optical Incremental Encoder).
It may be a mental encoder or a magnetic sensor that detects the passage of each tooth of the gear 115 and generates a number of signals corresponding to the number of teeth of the gear for one rotation of the gear. Based on the measured signals, the controller can determine the current angular position, angular velocity and respective accelerations of the unbalanced mass.

Information about the current values for the phase angle and speed of the main engine is transmitted to the controller. By comparing this information with the corresponding current value for the movement of the unbalanced mass, the controller controls the signal to the drive motor 113 to synchronize the two movements.

The two shaft sections are hollow and have right-hand and left-hand inner spiral teeth 204, 205, respectively. The central shaft 206 is mounted so that it can be displaced longitudinally in the direction of the axis of rotation inside the two shaft sections and has two sections 207 with opposing helical teeth engaging corresponding helical teeth on the shaft sections. , 208. The helical portion converts the longitudinal displacement of the shaft 206 into opposing rotational movements of the two unbalanced weights.

The gear 115 is supported by bearings (not shown) in the housing 102 and mounted on the shaft 206 in a non-rotatable manner, but is displaced longitudinally by an associated spline 209 parallel to the gear and shaft axis. it can. Via gear 115 and transmission belt 114, drive motor 113 exerts a torque on the central shaft, which is transmitted to the unbalanced weights via the helical teeth and rotates these unbalanced weights as a unitary movement. Can be.

If it is desired to start the device, the unbalanced weight is rotated relatively so that the common center of mass of the unbalanced mass is closer to the axis of rotation. This is done by means of a regulating device, which consists of a carrier part 210 mounted at the end of the central shaft and located inside the piston means 211, the piston 212 of the piston means comprising a pressure chamber connected to the fluid channels 138, 139. Located within 213, fluid channels 138, 139 communicate with chamber ports on opposite sides of the piston, respectively, and connect to pressure source 141 and drain 142 via control valve 140, respectively. In the position of the valve 140 shown, the chamber port on the left side of the piston is pressurized to hold the piston in the position shown, which is regulated by an adjustable stop 215 against the outer surface of the pressure chamber housing. Is done.
In this position, the unbalanced weight is at the second active angular position. If the device is to be started from a standstill, the valve 14
Switching 0 causes fluid pressure to act on the right side of the piston 212, moving the piston to the left to the second extreme position. As a result, the carrier portion 210 displaces the central shaft longitudinally and carries the unbalanced weights to the first position, with the centers of mass of these weights diametrically opposed on either side of the axis of rotation. Rotational movement of the shaft with respect to the fixed carrier portion is enabled by bearings 214.

The first relative angular position of the unbalanced weight is shown in FIG. 2, in which the masses M ₁ , M _{2 of the} unbalanced weight are shown.
Are diametrically opposed on either side of the axis of rotation, the common center of mass M _{1 + 2} is as close as possible to the axis of rotation, and the unbalance of the unbalanced mass is minimized. In the illustrated example, the common center of the masses of the two unbalanced weights coincides with the rotation axis, and the degree of unbalance is zero.

When the unbalanced mass rotates, the control valve 140 is switched at an appropriate time, and the unbalanced weight is changed to the second value.
Rocking to a position to give the unbalanced mass the desired degree of unbalance. Fluid drain 142 may have an orifice that controls the spilled oil such that a shift occurs, for example, in 20 seconds. This second position can be adjusted by adjusting the stopper 215. FIG. 4 shows a state in which, for example, the unbalanced weight can reach the other extreme position only by relatively rotating by a small angle α. The common center M _{1 + 2} of the unbalanced masses in this state (position) is only slightly away from the axis of rotation, and the unbalanced masses have a small degree of unbalance.

As can be seen from FIGS. 2-4, the common center M _{1 + 2} of the unbalanced mass changes its angular position with respect to the rotation axis 7 when the unbalanced weight rotates relatively. This changes the phase correction value for the motion of the unbalanced mass with respect to the main engine. The controller may include a correction table for the correlation between the phase correction and the relative angular position of the unbalanced weight.

The vibration sensor can be mounted on the hull of the ship at a location known from experience to be an anti-node of vertical hull vibration or one end of the ship, or on the main deck. This sensor is connected to the controller and based on the measured current hull vibrations, the controller fine-tunes the relative angular position of the unbalanced weight so that the compensation moment is continuously adjusted to the optimal vibration damping value. Can be adjusted.

The present invention can provide a vibration compensator having a substantially greater degree of imbalance than conventional compensators. 300
Compensators that can provide imbalance up to kg x m are known. According to the invention, 55 having a center of mass M _{1 + 2} located at a distance r of 53.7 cm from the rotation axis 7.
For example, 300 corresponding to an unbalanced mass weighing 90 kg
Unbalances of up to 0 kg × m can be used.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of an apparatus according to a first embodiment of the present invention.

FIG. 2 is an end view showing a first angular position of two unbalanced weights of the device of FIG. 1;

3 is an end view of the device of FIG. 1 showing a second angular position of two unbalanced weights.

FIG. 4 is an end view showing a third angular position of two unbalanced weights of the device of FIG. 1;

[Explanation of symbols]

 7 Rotating shaft 102 Housing 104, 110 Unbalanced weight 113 Drive motor 114 Transmission belt 201, 202 Shaft part 204, 205 Helical tooth part 206 Central shaft 207, 208 Helical tooth part 215 Stopper

──────────────────────────────────────────────────続 き Continued on front page (73) Patent holder 594140904 Center Sid, 161 Stam holmen, DK-2650 HVIDO VRE, Denmark (58) Fields investigated (Int. Cl. ⁷ , DB name) F02B 77/00 F16F 15 / 22 F16H 33/04

Claims (3)

(57) [Claims] An apparatus for compensating for free moments due to inertial forces in a piston propulsion engine of a ship, such as a large two-stroke crosshead engine,
An unbalanced mass mounted at a predetermined distance from the engine in the longitudinal direction of the ship and rotatable about a horizontal axis, a driving means for rotating the unbalanced mass, and the rotation speed and phase of the unbalanced mass A control device for controlling the angle as a function of engine speed and phase angle, wherein said unbalanced mass rotatable as a unit comprises two unbalanced weights, a first unbalanced weight (104) and a second unbalanced weight. The weights are divided into counterweights (110), each of which is mounted coaxially with a common horizontal axis of rotation and housing (102).
Eccentrically mounted to a corresponding shaft portion (201, 202) extending therein; said shaft portion being hollow;
One shaft portion is right-handed and the other shaft portion is left-handed inside spiral teeth (205,
205); a central shaft (206) coaxial with the axis of rotation mounted so as to be longitudinally displaceable within the housing; and wherein the inner helical teeth of the shaft portion are mounted on the central shaft. The corresponding outer helical teeth (207, 208) of the first and second positions; the adjusting device is adapted to have a first position in which a common center of the mass (M _{1 + 2} ) of the unbalanced weight is located near the rotation axis. The central shaft (206) for moving the relative position of the unbalanced weight with respect to the rotational axis during rotational movement between the second position where the common center of mass is further away from the rotational axis. Characterized in that it can be displaced in the longitudinal direction. 2. The compensator according to claim 1, wherein said drive means (113, 114) for rotating said unbalanced mass acts on said central shaft. 3. The compensating device according to claim 1, wherein the displacement of the central shaft is limited by an adjustable end stop.