JP2000145880A - Vibration compensator for internal-combustion engine and method for starting the compensator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a vibration compensator for an internal-combustion engine capable of phase lock and offer a starting method for the compensator. SOLUTION: A vibration compensator for an internal-combustion engine has at least one unbalance mass 6 mounted on a shaft 7 eccentrically. The mass 6 is driven by a motor 11. The drive motor 11 works as a synchronous motor when the engine is in continuous operation. The revolutionary speed of the motor 11 is synchronized with the AC voltage whose frequency forms a specified ratio to the revolutionary speed of the engine.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a vibration compensator for an internal combustion engine, in particular a two-stroke crosshead engine, the compensator comprising at least one unbalanced mass (un).
This unbalanced mass is mounted eccentrically on a shaft which can be rotated by a drive motor at a predetermined frequency adapted to the speed of the internal combustion engine.

[0002]

2. Description of the Related Art Vibration compensators of this kind are well known in marine engine plants and are described, for example, in EP 001097.
No. 3. The compensator reduces or perfectly balances selected forces or moments generated by operation of the internal combustion engine. Without compensation, the selected forces or moments cause the internal combustion engine to vibrate inappropriately with associated elements, such as a shaft system.

[0003] In order to provide the desired vibration damping, the vibration compensator must follow the engine speed at a specific phase angle with respect to the internal combustion engine, ie, during continuous operation, the compensator must be phase locked to the engine. phase l
ock). This is, for example,
This is accomplished by adjusting the amount of hydraulic drive fluid supplied under pressure to the hydraulically actuated drive motor, thereby effectively and continuously adjusting the drive motor.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to provide another solution for achieving a phase lock between a vibration compensator and an internal combustion engine.

[0005]

SUMMARY OF THE INVENTION In view of this object, a vibration compensator according to the present invention is characterized in that, when a drive motor is continuously operated, an alternating current whose frequency has a predetermined fixed ratio with respect to the rotation speed of the internal combustion engine is provided. It is characterized in that it operates as a synchronous motor whose phase angle and rotation speed are synchronized according to the voltage.

[0006] The synchronous motor can be controlled without any control.
It has the characteristic that it operates in a phase-locked state with respect to the AC voltage that supplies power to the synchronous motor. By using a drive motor that acts as a synchronous motor during continuous operation, and by supplying an AC voltage to the drive motor as electrical power at a frequency that makes a predetermined fixed ratio to the speed of the internal combustion engine, The required phase lock has been provided between the internal combustion engine and the simple means and in a purely electrical manner.

Preferably, the drive motor acts as an asynchronous motor when starting the vibration compensator and acts as a synchronous motor during the continuous operation mode. Thus, the drive motor itself can accelerate the vibration compensator from a stopped state to a synchronous speed in continuous operation mode without using auxiliary drive transport. This provides a very simple and reliable compensator design.

In another design, the drive motor is a synchronous motor started by a separate start drive. This is done to alleviate the disadvantage of synchronous motors that there is no starting torque when stopped. The starting drive is, for example,
It may be an asynchronous motor or a hydraulic motor connected to the shaft of the unbalanced mass by a drive connection.

Of course, an electric drive motor can be used to rotate an unbalanced mass having a horizontal shaft, but the shaft with the unbalanced mass is driven by a drive motor having a substantially vertically extending axis of rotation. Is preferred. The magnitude of the required drive torque is thus suitably small, so that a standard manufactured electric motor can advantageously be used. When an internal combustion engine is used on a ship, movement occurs when the weight of the ship changes and during navigation, making the axis of rotation acute with respect to the vertical. When using the term vertical in connection with the present invention, it should not be understood that it is physically vertical, but simply a direction that extends more or less upwards and downwards.

In an embodiment which is particularly suitable for stationary or marine engines with a constant speed, the AC voltage is taken from a power supply network in which a generator driven by an internal combustion engine generates power. Since the generator operates synchronously with the supply network, the supply network can thus be used directly as an efficient means for phase locking the vibration compensator to the internal combustion engine.

In an embodiment particularly suitable for variable speed marine engines, the AC voltage is derived from a frequency converter whose frequency is controlled by a rotary pickup device which samples the angular movement of the engine's rotating shaft, such as a crankshaft. . Although this embodiment can be applied to an engine having a constant rotation speed, it is not preferable for such an engine because both a rotation speed pickup device and a frequency generator are required.

If the vibration compensator has a vertically extending axis of rotation, advantageously two unbalanced masses associated with the drive motor can be mounted on the internal combustion engine. Depending on the relative direction of rotation and the relative phase difference, the unbalanced mass is generated such that the forces from the two compensators generate pulsating external forces acting only in a few specific directions to balance each other in orthogonal directions. , Can be formed.

[0013] The torsional effect about the horizontal longitudinal axis exerts on the engine frame, causing annoying lateral vibrations of the engine top when the two ends of the engine vibrate in opposite phases. In order to compensate for the so-called X-type induced moment, two unbalanced masses may be mounted at the front end and the rear end of the internal combustion engine, these unbalanced masses being 180 ° by the drive motor. It is driven with a relative phase difference and the same rotational direction. With respect to phase, the operation of the unbalanced mass is adjusted with respect to the internal combustion engine such that the two changing lateral forces generated by the unbalanced mass directly affect the lateral movement of the engine top. This reduces lateral movement of the top of the engine.

Furthermore, the two unbalanced masses are mounted at one end of the engine, for example at the base of the thrust bearing of the shaft, and are driven by a drive motor with a relative phase difference of 0 ° and in opposite rotational directions. . This produces a variable axially directed force to dampen axial vibrations from the propeller shaft and the intermediate shaft.

Furthermore, it is possible to dispose two unbalanced masses at the top of the engine and drive these masses with a relative phase difference of 0 ° and in the opposite rotational direction, so that pulsation is generated. The pulsating force acts in the longitudinal direction of the engine in accordance with the phase angle with respect to the engine to compensate for the L-shaped vibration of the engine top, or acts laterally to cause the engine top to vibrate laterally. Compensating for the induced moment of the mold, the two ends of the engine oscillate in phase, i.e. simultaneously towards the same side.

The invention further relates to a vibration compensator comprising two unbalanced masses mounted eccentrically on a shaft driven by an associated drive motor and a method for starting an internal combustion engine. The method starts the drive motor, rotates the unbalanced mass to approximately a synchronous speed with respect to the effective supply network, synchronizes the phase angle and speed of the two unbalanced masses according to the supply network, and synchronizes each other accordingly. Let it. The drive motor then operates as a synchronous motor and subsequently starts the internal combustion engine and synchronizes according to the compensator.

Starting the unbalanced mass before the internal combustion engine provides a good time to perform the synchronization and allows the synchronization to be performed individually. That is, one unbalanced mass can be synchronized first at a predetermined time, and then the internal combustion engine can be synchronized.

Another possibility is to start the internal combustion engine, drive the generator operating the supply network, start the drive motor, rotate the unbalanced mass to approximately synchronous speed with respect to the supply network, The phase angle and rotation of the balancing masses are synchronized with the supply network and with each other and with the internal combustion engine. At that time, the drive motor operates as a synchronous motor. This solution is particularly suitable in the case of ships where most of the power to the supply network is supplied by the generator of the internal combustion engine.

The present invention will now be described in detail with reference to the accompanying schematic drawings.

[0020]

DESCRIPTION OF THE PREFERRED EMBODIMENTS An internal combustion engine 1 is drivingly connected to a generator 3 via a shaft 2. The generator 3 generates an alternating current with respect to a power supply network denoted by reference numeral 4. The engine may be, for example, a two-stroke crosshead engine with an output of 4 MW to 60 MW, depending on the size of the engine, or another large diameter internal combustion engine such as a four-stroke engine. The large bore engine has a cylinder bore of at least 200 mm and the engine is the prime mover of a stationary power plant,
Alternatively, it is a marine engine that drives a propeller shaft. In the case of a marine engine, the generator is driven directly by the engine shaft and is mounted on the front or intermediate shaft of the engine or driven via gears.

The engine 1 has a vibration compensator 5 with an unbalanced mass 6. This unbalanced mass is provided at the front and rear ends of the engine at the top of the cylinder section, respectively, which provides the maximum possible distance down to the neutral axis of the engine frame lateral vibration.

FIG. 2 shows that the unbalanced mass 6 is mounted eccentrically on a vertically extending shaft 7. The shaft is rotatably supported by bearings (not shown) provided on the horizontal upper and lower walls of the compensator housing 8 mounted, for example, by welding or bolting to the cylinder section 9 of the engine. The shaft 7 projecting upward through the upper wall supports a drive pulley 10 driven by an electric drive motor 11 via a belt or chain drive. The transmission between the drive motor and the shaft can of course also be done by other methods, such as a conventional gearing using gears.
If the drive motor operates at the same speed as the unbalanced mass 6, the drive motor can also be mounted directly on the shaft 7.

The drive motor 11 is preferably a reluctance motor exhibiting special characteristics that acts as an asynchronous motor during startup and acts as a synchronous motor during synchronous rotation. The drive motor is, for example, an ABB three-phase induction motor in which the rotor has protruding magnetic poles and the stator has three-phase windings.
MTL type motors are preferred. The motors are connected in a star connection.

The rotational speed and transmission of the drive motor are determined so that the unbalanced mass obtains a specific frequency corresponding to the vibration frequency to be damped. As an example, compensation for lateral vibrations of the engine frame in which a sixth-order inductive moment occurs can be considered. Internal combustion engines are typically
103.4 rpm or 10 depending on whether the frequency of the supply network is between 50 Hz and 60 Hz.
Operates at 2.9 rpm. Thus, the internal combustion engine
It provides a fundamental frequency of 1.723 Hz or 1.715 Hz, and a frequency of sixth order vibration, and thus it can be seen that the rotational frequency of the unbalanced mass is either 10.24 Hz or 10.29 Hz. In the case of the drive motor 11 in which eight magnetic poles are arranged in four magnetic pole pairs, 750 rp
m, which corresponds to 12.5 Hz at a network frequency of 50 Hz. Thus, the transmission ratio between the drive motor and the shaft 7 is 1:
0.827. For a drive motor with four magnetic poles arranged in two magnetic pole pairs, the frequency must be 25 Hz and the transmission ratio must be 1: 0.414.

The drive motor may be connected to an active supply network and driven by an AC voltage drawn from the network. When the drive motor starts, it gets most of the starting torque as an asynchronous motor, which starts the unbalanced mass. As the drive motor approaches the synchronous speed, the torque drops and enters an oscillation region where the rotor poles are phase locked to the network frequency, after which the drive motor operates as a synchronous motor.

When the two drive motors are started individually and both motors are phase locked to the network frequency, the two unbalanced masses often do not operate at the desired mutual phase angle. This is because these unbalanced masses must typically have a relative phase difference of either 0 ° or 180 °. Thus, by briefly interrupting the supply of AC voltage to one drive motor, rotating the rotor itself with respect to the network by one or more pole pairs, and changing the phase angle,
The two drive motors are synchronized with each other. Starting the internal combustion engine when the two unbalanced masses are perfectly synchronized,
The synchronized generator 3 is synchronized at a predetermined phase angle according to the network to provide the desired synchronization with respect to the unbalanced mass. For synchronization purposes, each of the unbalanced masses and the internal combustion engine are provided with a zero indicator. The zero indicator generates a position signal each time a predetermined portion of the movable part passes a stationary sensor.

Only when the internal combustion engine is running,
If the supply network is active, it is necessary to start the internal combustion engine first and then the vibration compensator.
When the speed of the internal combustion engine is variable, as in the case of a main engine of a ship with a fixed pitch propeller (FPP), the vibration compensator is driven by an AC voltage taken from a frequency converter (not shown). The phase can be locked with respect to the internal combustion engine by the drive motor 11 that is operated.
The frequency converter may be, for example, a device having a VLT display made by Danfoss. The frequency converter
An angular encoder that samples the movement of the shaft of the internal combustion engine generates a frequency that is controlled to correspond to the associated speed of the internal combustion engine. Angle encoders and frequency converters are both standard components used in connection with internal combustion engines.

In FIG. 3, the vector F shows the force from two unbalanced masses 6 located at each end of the top of the engine. The unbalanced mass has a relative phase of 0 ° and rotates in the opposite direction. These forces F can be decomposed into two axially acting forces Fa that balance one another and two lateral forces Ft, external forces affecting the respective ends of the engine. These forces compensate for oscillations from the H-type induced pressure moment.

In FIG. 4, the vector F represents the force from two unbalanced masses 6 located at each end of the top of the engine. The unbalanced mass has a relative phase of 180 ° and rotates in the same direction. These forces F are two mutually balanced forces Fa acting in the axial direction and two lateral forces Ft, external forces affecting the respective ends of the engine.
Can be decomposed into These forces compensate for oscillations from the X-type induced pressure moment.

[Brief description of the drawings]

FIG. 1 is a schematic view of the profile of an internal combustion engine having a vibration compensator according to the present invention.

FIG. 2 is an enlarged schematic view of one of unbalanced masses provided in the engine shown in FIG. 1;

FIG. 3 is a schematic diagram showing an external lateral force generated by a vibration compensator for compensating for an H-shaped vibration.

FIG. 4 is a schematic diagram showing an external lateral force generated by a vibration compensator to compensate for X-type vibration.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Internal combustion engine 2 Shaft 3 Generator 4 Power supply network 5 Vibration compensator 6 Unbalanced mass 7 Shaft 8 Compensator housing 9 Cylinder section 10 Drive pulley 11 Electric drive motor

 ────────────────────────────────────────────────── ─── Continuation of the front page (71) Applicant 594140904 Center Syd, 161 Stamholmen, DK-2650 HVIDOVR E, Denmark (72) Inventor Lars Waldemar Winnsens Bründum Daeco-2920 Charlotte Rütten, Denmark, Denmark Vai 9

Claims (11)

[Claims] 1. An eccentrically mounted shaft (7) for an internal combustion engine (1), in particular a two-stroke crosshead engine, which can be rotated by a drive motor (11) at a frequency adapted to the rotational speed of the internal combustion engine. A vibration compensator (5) having at least one unbalanced mass (6), wherein the drive motor (11) has a frequency with respect to the rotation speed of the internal combustion engine (1) during continuous operation of the internal combustion engine. Wherein the phase angle and the rotation speed act as a synchronous motor in accordance with an AC voltage having a predetermined ratio. 2. The vibration compensator according to claim 1, wherein the drive motor acts as an asynchronous motor when starting the vibration compensator, and acts as a synchronous motor when in a continuous operation mode. . 3. The vibration compensator according to claim 1, wherein the drive motor is a synchronous motor started by a separate start drive. 4. The shaft (7) with the unbalanced mass is driven by the drive motor (11) having a substantially vertically extending axis of rotation. 4. The vibration compensator according to 2 or 3. 5. The method according to claim 1, wherein the AC voltage is taken from a power supply network (4) that generates power by a generator (3) driven by the internal combustion engine. A vibration compensator according to any one of the preceding claims. 6. The apparatus according to claim 1, wherein the AC voltage is taken from a frequency converter whose frequency is controlled by a rotary pickup device that samples an angular movement of a rotary shaft of an engine such as a crankshaft. The vibration compensator according to any one of the above. 7. Vibration according to claim 1, wherein two unbalanced masses (6) associated with the drive motor (11) are mounted on the engine. Compensator. 8. The two unbalanced masses (6) are mounted on a front end and a rear end of the internal combustion engine (1), and these unbalanced masses are shifted by 180 ° by the drive motor (11). The vibration compensator according to claim 7, wherein the vibration compensator is driven with the relative phase difference and in the same rotation direction. 9. The two unbalanced masses (6) are mounted on at least one end of the engine (1) and are driven by the drive motor (11) with a relative phase difference of 0 ° and opposite. The vibration compensator according to claim 7, wherein the vibration compensator is driven in the rotation direction. 10. A vibration compensator (5) comprising two unbalanced masses (6) eccentrically mounted on a shaft (7) driven by an associated drive motor and a method for starting an internal combustion engine (1). , The drive motor (11)
Rotating the unbalanced mass (6) with respect to the effective supply network (4) to approximately a synchronous speed, synchronizing the phase angle and the rotational speed of the unbalanced mass according to the supply network and each other, When the drive motor operates as a synchronous motor, subsequently starting the internal combustion engine (1) and synchronizing according to the compensator. 11. A vibration compensator (5) comprising two unbalanced masses (6) eccentrically mounted on a shaft (7) driven by an associated drive motor and a method for starting an internal combustion engine (1). , The internal combustion engine (1)
Starting the generator (3) operating the supply network (4), starting the drive motor (11), rotating the unbalanced mass (6) to approximately a synchronous speed with respect to the supply network, Synchronizing the phase angle and rotation of the unbalanced mass according to a supply network and each other, wherein the drive motor (11) operates as a synchronous motor.