JP4748932B2 - Engine equipment - Google Patents

Description

  The present invention transmits a control signal to synchronize the operation of two internal combustion engines by both the two engines for propeller operation and the speed and mutual phase angle settings in the first mode of operation. And a control unit configured so that an external moment from the engine opposes an external moment from the other engine.

  Such an engine device is described in U.S. Pat. No. 4,245,955, and according to this engine device, an aircraft engine consisting of two engines operates in synchronism with the total external moment from the two engines. Is designed to be properly reduced. Therefore, vibrations in the passenger compartment can be reduced when the aircraft carries the passenger. If another vibration pattern in the aircraft is desired, the pilot can adjust the phase difference between the engines by means of an adjustment button.

Furthermore, the prior art describes a marine engine in which two rotating counterweights are attached to the end of the engine and driven by a chain drive connected to the camshaft or a separate chain drive from the crankshaft. Contains. The counterweights rotate in opposite directions at twice the speed of the crankshaft.
U.S. Pat. No. 4,245,955

  The object of the present invention is to reduce the need to use rotating counterweights driven by chain drives or toothed wheel drives in marine engines.

  In view of the above object, the engine device of the present invention is a two-stroke crosshead engine in which each engine has 4 to 7 cylinders and a secondary external moment from each engine is the engine. The control unit has a second operating mode in which only one engine is operating and receives control signals independent of the other engine. It is a feature.

  Uncorrected transmission of the secondary external moment from the engine to the hull of the ship obviates the use of a rotating counterweight driven by the crankshaft. When two engines operate at approximately the same speed and a mutual phase angle that causes the secondary external moment from one engine to oppose the secondary external moment from the other engine, the hull of the ship is Even if not used to balance moments, the normal continuous maximum output (MCR) will not be affected by inappropriately large moments.

  When only one engine is operating, the engine is controlled without tuning to the stopped engine. In this case, the hull of the ship will be affected by the free second moment from the operating engine, which typically produces an output corresponding to the total output of the two engines. Having less than half of the corresponding impact from a large engine. As a result of this substantially reduced effect, the level of hull vibration is below the limit for acceptable hull vibration. The division of the engine power between the two propulsion engines applies to the fact that the secondary external moment is lower than the limit value of the moment effect on the hull when only one engine is operating. When both engines are operating and the total secondary external moment exceeds this limit, the external moment of one engine is used to balance the external moment of the other engine and The resulting moment effect is less than the limit value.

  Compared to an engine device having only one engine, the division of power between the two engines provides the complementary advantage of improving the reliability of operation of the engine device. If one engine fails, the other engine can continue to operate until the failed engine is repaired. This extra safety against global outages is particularly useful in ships such as tankers, bulk carriers and LNG carriers where the overall outage may involve significant danger.

  The two engines preferably operate each propeller by separate shafts. This is because this typically results in the placement of opposing engines on either side of the longitudinal vertical center plane of the ship's hull. In this case, the stern typically has two stern tubes and may be a so-called twin-skeg design or a comparison in which the stern tubes appear on each side of the stern material. It may be a general design. A symmetrical arrangement near the center plane of the ship is also advantageous for the mutual balance of external moments with respect to vibration. This is especially true when there is a large free moment from the H-type guide force moment, since the free moment from one engine can be used to balance the free moment from the other engine. apply. If there are many different types of free moments due to the varying need for cross-phase angle settings, the engine cross-phase angle settings are, for example, ideal for minimizing secondary external moments. It can be chosen as a compromise between the phase angle setting and the ideal mutual phase angle setting to minimize the free moment from the H-type guide force moment. In engine systems where different types of free moments have a common ideal cross-phase angle setting to minimize the resulting external moment, the engine cross-phase angle obtains this ideal cross-phase angle setting. To be controlled. Engines with associated propeller shafts may have the same direction of rotation (co-rotation) or the opposite direction of rotation (reverse rotation). As an alternative to the use of two separate propeller shafts, the two engines extend coaxially within a hollow shaft that drives one propeller and the other, if desired. It may have a common shaft that may be designed by a central shaft. The central shaft and the hollow shaft may be driven by each of the two engines. As yet another alternative, each engine may drive a generator that drives an electric motor associated with the propeller. This makes it possible to place the two engines in succession with each other at a suitable place in the ship.

In a preferred embodiment, the ratio between the sum of the amplitudes shown in Nm for the second order external moment and the engine equipment output shown in kW is in the range of 140 Nm / kW to 350 Nm / kW. . The sum of the amplitudes means that the effect on the external moment due to the amplitude of each of the two engines is simply a summed value regardless of whether they are balanced (equal) to each other. If one engine has an imbalance of 170 Nm / kW and the other engine has an imbalance of 175 Nm / kW, the sum of the unbalanced amplitudes for the two engines is 345 Nm / kW. In practice, a number of factors determine the limit of vibration energy that can be delivered to the hull without causing strong hull vibration that requires intervention in the form of use of a vibration modifier. It is therefore impossible to fix an absolute limit on the magnitude of the engine imbalance without the required vibration modifier. If the total unbalanced amplitude of the device consisting of the two engines is less than 140 Nm / kW, the two engines may possibly operate independently of each other without being synchronized with each other. Of course, synchronization may still provide advantages, but can be omitted. If the sum of the unbalanced amplitudes of the device consisting of two engines is higher than 350 Nm / kW, the operation of only one engine may excite too strong vibrations in the hull without any modification of the external moment. There is a fear that there is no. If the ship is not in any particular risk category due to the result of a stop, the contributions from the two engines are well balanced with each other, so the ship is affected by a relatively large imbalance in normal operating conditions. The need to be able to operate the ship for a long period of time with only one operating engine is not so great, and values higher than 350 Nm / kW are acceptable. At partial engine load, both engines operate at less than maximum power and the balance is still valid. The operation by one engine can be executed as an emergency operation for a fairly short time.

  The ratio between the sum of the imbalance amplitudes indicated by Nm with respect to the second order external moment and the engine equipment output indicated by kW indicates that when the proposed engine equipment is in operation, the vibration damper In order to provide extra certainty that it will not change as needed, it may suitably be between 140 Nm / kW and 275 Nm / kW.

  In a special design, the engine system includes two engines, each with seven cylinders, in this case relative to the ship's hull to balance each other in a manner similar to a second moment. It may be advantageous to transmit the external fourth moment without modification. Thus, no separate corrector is required for these external moments. Such a limit value may be based on shortening the period of the adjustment signal from the control unit. On average, this may result in a smoother operation of the engine over time.

It may be appropriate to design the control unit to allow a phase deviation of less than 10 °. Such a limitation may contribute to shortening the period of the adjustment signal from the control unit. On average, this may result in a smoother operation of the engine over time.

It is also appropriate for the control unit to allow a speed deviation of less than 15% of the desired speed. This relatively large deviation in speed without a correction signal from the control unit, especially when the wake area near the propeller at the rear of the hull surface changes periodically with the movement of the ship and the passage of waves in the sea. It may be appropriate if you are towing in a rough sea that you might do. These changes do not occur simultaneously for both propellers, which means that the propeller load changes with each other, which causes a difference in engine speed. Since this change is periodic, one engine will run slower than the other. This is therefore advantageous when the control unit only works on longer-term changes in the average speed of the engine.

The invention is explained in more detail below with reference to the drawings.
FIG. 1 shows the stern of a ship with a hull 1 in the form of a twin-skeg hull having two sterns 2. The two engines 3 are provided symmetrically around the longitudinal center plane 4 of the ship. Each engine is a two-stroke crosshead engine such as, for example, an MC or ME type MAN B & W Diesel engine. The MC engine has a camshaft that is driven by a chain drive from a crankshaft, and the ME engine is an electronically controlled engine that does not have a camshaft. These engines may have cylinder dimensions with a spacing of 24 cm to 110 cm, typically 40 cm to 90 cm. The total power of the two engines is typically over 2500 kW. The maximum continuous rated speed of the engine is 50 rpm to 300 rpm, preferably 50 rpm to 180 rpm.

  As shown in FIG. 1, each engine may have, for example, five cylinders 18 of the same dimensions. If less than four cylinders, the engine power is too small for the cost of building a separate engine. Engines with 8 cylinders usually have fine vibration characteristics with only a small external moment, so the present invention specifically has multiple cylinders with 4-7 cylinders for each engine. It is related with the engine apparatus. As mentioned above, external moments, which can also be called free moments, are transmitted to the hull of the ship without modification from the individual engines. Obviously, some buffering of external moments, and thus modifications, may occur in the engine floor and other structural members. Thus, the term “unmodified” should not be taken to mean that the external moment is necessarily transmitted 100% to the ship's hull, but rather that the external moment is substantially transmitted from the engine to the hull. And it should be taken to mean that no special positively correcting vibration dampener is used independently of the other engine to damp external moments from one engine from unacceptable to harmless levels. It is.

  The basic structure of a two-stroke crosshead engine is very well known and does not require detailed description. Each of the engines 3 is directly coupled to the propeller 5 via the shaft 6, and the shaft 6 may be constituted by a propeller shaft or may be constituted by one or more intermediate shafts and a propeller shaft. . The propeller is preferably a constant pitch propeller, although variable pitch propellers can also be used.

  In the first mode of operation with the operation of the two engines, the control unit 7 makes sure that the engine speed is synchronized and that the setting of these mutual phase angles is such that the external moments counteract each other. Sure. In one embodiment, the control unit may communicate control signals to both engines, providing the advantage that these engines are of exactly the same design. In another embodiment, one engine operates as a master engine without being controlled by the control unit, and the other engine operates as a secondary engine, which is the secondary engine. A control signal is received from the control unit to keep the engine synchronized with the master engine. In this case, the master engine is provided with a sensor unit that samples data on the angular position of the crankshaft and transmits a signal related to the angular position to the control unit.

  External moments from the engine may cause the hull to vibrate. A number of different factors determine whether a specially sized external moment causes a noisy vibration. One factor is the form of vibration, in which the vertical vibration mode is important when the external moment is secondary. FIG. 2 shows the contour of the hull 1 of the ship, with a vibration mode a for vertical hull vibrations due to three intersections and a vibration mode b for vertical hull vibrations due to four intersections 15.

  Another factor is the frequency of the external moment. The secondary external moment has a number of cycles per minute (cpm) that is twice the speed of the engine. The external moment may provide an undesirably large amount of energy in the vibration mode when the frequency of the external moment matches or is close to the natural frequency of the vibration mode.

  Thus, the third factor is the natural frequency of the various vibration modes. These natural frequencies depend on the main dimensions and the hull structure of the ship and to some extent also on the load conditions. FIG. 3 shows an empirical relationship between the load tonnage (1,000t) for the carrier and the natural frequency of the vibration mode with 2, 3, 4 and 5 intersections in vertical hull vibration. Data are shown. For each vibration mode, the eye area indicates the interval of natural frequency.

  Next, an embodiment of the control unit 7 will be described in more detail with reference to FIG. Each engine is provided with a sensor unit 8 that samples the angular movement of the crankshaft. The sensor unit 8 includes, for example, a sensor that transmits a signal every time a zero indicator on the shaft passes the sensor, and one signal is transmitted for each rotation of the shaft. The sensor unit 8 also has one or more sensors that transmit one signal each time the shaft rotates a predetermined number of times, such as transmitting one signal for every 45 ° shaft rotation. Also good. The signal may be transmitted, for example, when a marker mounted on the shaft passes the sensor. The sensor unit may be of the type known as an optical incremental encoder. This may carry an amplified digital signal about the angular movement of the engine.

  Data relating to the angular movement of the engine is transmitted from the sensor unit 8 to the control unit 7 via the signal line 9 and stored in the data correction unit 10 in the control unit 7, and the comparator 11 receives data from the data correction unit 10. And calculate the current speed difference between the engines and the current cross-phase angle difference between the engines. Any difference in engine speed is stored in the rotational error store and then compared to a predetermined limit value for rotational error. If the limit value is exceeded, the pulse indicator 12 transmits a correction signal via the signal line 13 to the engine control unit 14 for one engine.

  When one engine is the master engine, the correction signal is transmitted to the engine control unit 14 of the auxiliary engine. When the engine is provided, the control unit 7 is integrated with, for example, the engine control unit 14, and the engine control unit 14 determines whether the engine apparatus supplies an output higher or lower than a desired output. It is possible to select an engine that receives a signal based on the data indicating the above. If the engine power is too high, the faster engine will be given a correction signal to move slower, and if the engine power is too low, the signal to move faster to the slower engine. May be given.

  The value of the phase difference between the engines calculated by the comparator 11 is compared with a predetermined value for the desired phase difference, and the difference between these two values is stored as a phase error. The phase error is then compared to a predetermined limit value for the phase error, and if the limit value is exceeded, the pulse indicator 12 sends a correction signal via signal line 12 to the engine control of one of the engines. Transmit to unit 14. This signal may be transmitted to one of the two engines, or may be transmitted to the secondary engine when one engine is the master engine.

  The desired phase difference depends on the position of the engine in the ship with respect to the placement of the intersection. FIG. 5 shows an embodiment in which both engines are arranged after the last intersection 15 in a vibration mode with three intersections. For reasons of illustration, the engines are depicted as being stacked at the same position in the longitudinal direction of the ship, but the engines are side-by-side, i.e., the same length separated from each other in the direction across the ship. It should be understood that the directional positions are arranged. In this case, the desired phase difference is 180 ° so that the vertical force pair 17 is in opposite phase to the extent possible. FIG. 6 shows the engine 3 to be arranged in a state where the intersection 15 is arranged between the engines that drive the generator 16. In this arrangement of the engine with respect to the intersection point, the desired phase difference is 0 ° because the vertical force pair affects the vibration mode by a moment directed in the opposite direction about the intersection point.

Another embodiment of the control unit 7 is a so-called flip-flop unit as described in US Pat. No. 3,367,110.
The advantages of the present invention are illustrated by an example. A carrier engine device with a dwt of 100,000 tons requires a propulsion power of at least 18,900 kW. This output may be supplied by a device consisting of a common single engine in the form of a MAN B & W Diesel 5S80MC-C engine. This engine has an output of 19,400 kW at a speed of 76 rpm. This engine has a secondary freedom of 4,895 kNm at 152 cpm, corresponding to the ratio between the unbalance requiring the use of an unbalanced weight to reduce the imbalance and the engine unit output of 252 Nm / kW. Has an imbalance in moments.

  In the design of the engine device according to the invention as a device consisting of two engines, the propulsive power can be supplied by two 6S50ME-C engines, each with a power of 9,480 kW at a speed of 127 rpm. Each engine has an imbalance in a second free moment of 771 kWNm at 254 cpm, corresponding to a ratio of 81 Nm / kW between the imbalance and the engine power when running alone. It is immediately apparent that the output imbalance is significantly reduced. When both engines are operating, the imbalance is substantially balanced. These low levels of imbalance can be tolerated without further action and a rotating counterweight is not required to dampen the imbalance.

  The above description of embodiments of the invention may be combined with each other to form new embodiments that fall within the scope of the claims.

FIG. 1 is a diagram showing an outline of an engine apparatus according to the present invention. FIG. 2 is a diagram illustrating an example of a vibration mode in a ship body. FIG. 3 is a graph showing an example of resonance that occurs between an external member and vibrations in the ship's hull. It is a schematic block diagram of embodiment of a control unit. It is a block diagram which shows the engine apparatus provided with the two engines attached in the stern after the intersection of the vibration of the present ship body. It is a block diagram which shows the engine apparatus provided with the two engines attached in the stern before and after the intersection of the vibration of the present hull.

Explanation of symbols

2 stern, 3 engine, 5 propeller,
6 shaft, 7 control unit, 8 sensor unit,
9 signal lines, 10 data correction units,
11 Comparator, 12 Pulse indicator,
13 signal lines, 14 engine control units,
15 intersections, 16 generators, 18 cylinders,

Claims (3)

It has two engines (3) for operating each propeller (5) by a separate shaft (6 ) in the ship (1) and a control unit (7), which control unit In operating mode, a control signal is transmitted to synchronize the operation of the two engines (3) by both speed and mutual phase angle setting, so that an external moment from one engine is external to the other engine. An engine device designed to counter a moment,
A secondary external moment of the type where each engine (3) is a two-stroke crosshead engine with seven cylinders (18) and produces vertical vibrations of the hull from the individual engines (3). Engine transmitted to the hull of the
The control unit (7) has a second operating mode in which only one engine is operating and receives a control signal from the control unit (7) and the other engine is stopped ;
An engine device in which a fourth-order external moment is transmitted to the hull of the ship. The engine device according to claim 1 ,
Engine device, wherein the control unit (7) is adapted to allow a phase deviation of less than 10 °. The engine device according to claim 1 or 2 ,
Engine device, wherein the control unit (7) is adapted to allow an engine speed deviation of less than 15% of the desired speed.

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