High Power Marine Gearbox with PTO and PTI Functions

This technical article focuses on a high – power marine gearbox with PTO (Power Take – Off) and PTI (Power Take – In) functions. Traditional marine gearboxes have limitations, such as a lack of PTO and PTI functions, which can’t meet the diverse needs of ships. The new gearbox is composed of a hydraulically controlled clutch and gear transmission, working in conjunction with an adjustable pitch propeller. In PTO mode, the main engine drives the integrated motor for power generation, making use of residual power and enabling battery charging. In PTI mode, the shaft – driven generator gets power from the ship’s power grid for propulsion, enhancing ship maneuverability and achieving “zero” emissions. The gearbox is designed to overcome the drawbacks of traditional ones, offering advanced functions, low cost, high reliability, and high precision. It can reach six working states. The PTO and PTI clutches are arranged in series to realize different functions. With a reduction ratio range of 2:1 to 6:1 and a rated input transmission capacity of 3.448kw/rpm, it can withstand a propeller push – pull force of 450KN. This gearbox is suitable for multi – purpose work boats and ocean fishing vessels, leading the way in marine transmission with its high – efficiency, intelligent, and reliable mechatronic hybrid features.

Background Technology

High-power marine gearboxes belong to the transmission device of the ship’s propulsion system, which is generally controlled by gas-electric operation and has functions such as reverse, clutch, deceleration and can withstand propeller thrust. The design of marine gearboxes has high reliability requirements, especially for high-power gearboxes used on ocean-going ships. Ocean-going transport ships run and propel continuously at sea day and night for several months, or even more than half a year. Once the power system fails, it will cause unimaginable consequences. Traditional gearboxes generally only have three working states: reverse, forward, and stop. They do not have the functions of auxiliary power input (PTI) and auxiliary power output (PTO). When the main propulsion diesel engine fails, the ship cannot sail normally; when the ship encounters wind and waves, it will appear to be underpowered. It cannot meet the user’s requirements for the multi-function of the ship.

Working Mode

PTO mode is the basic working mode,in this working mode, the ship’s main engine drives the integrated motor through the mechatronic gearbox, and the motor works in the power generation mode. When the ship is “launched and sailing”, the residual power of the main engine is large, and this torque-controlled shaft-driven generator can be used to enable the main engine to generate power from idle to rated speed. At this time, the battery pack can also be charged. When the system works in hybrid power mode, the battery can be discharged to provide energy to achieve the purpose of energy saving.

In PTI mode, the shaft-driven generator obtains power from the ship’s power grid for ship propulsion. This mode can effectively improve the maneuverability of the ship by reasonably selecting the power distribution of the main engine and the shaft generator according to the ship’s demand for speed. The electric drive solution can provide an additional 10% to 15% (configurable according to user requirements) of the ship’s engine power, which is suitable for the operation conditions of the ship’s peak load value. Through this additional PTI interface, the ship’s “zero” emissions can be achieved.

Technical Purpose and Implementation Method 

The purpose of this technology is to overcome the shortcomings of existing designs and provide a multifunctional high-power gearbox with more advanced functions, low cost, good reliability and high precision than traditional gearboxes. In addition to the main output, the gearbox also has the functions of auxiliary power input (PTI) and auxiliary power output (PTO). The auxiliary power input can drive the ship to return to port in an emergency when the main engine fails; it can also play a role in assisting the ship when it encounters wind and waves. The auxiliary power output can generate electricity when the ship needs it.

The purpose of this technology is achieved through the following technical solution, which includes at least a box body, and the input shaft and input cylinder of the gearbox are made into one body, hereinafter referred to as the input shaft cylinder . The input shaft oil cylinder is installed in the housing through the bearing. One end of the input shaft oil cylinder is connected to the power through the input flange and the high elastic coupling. The other end of the input shaft oil cylinder is connected to the main clutch. The main clutch is supported by the bearing. The main clutch is connected to the transmission shaft gear through the interference fit key. The transmission shaft gear meshes with the output gear on the output shaft. The gear sleeved on the clutch meshes with the gear sleeved on the auxiliary transmission shaft. The auxiliary transmission shaft is provided with an auxiliary output clutch and an auxiliary input clutch, and is fixed with an output flange. An auxiliary input gear is also sleeved on the auxiliary shaft, which meshes with the transmission gear fixed on the transmission shaft.

The main clutch is supplied with oil by a large belt pump, while the PTO and PTI clutches are supplied with oil by a small belt pump. The gearbox is equipped with a spare pump, which is connected to the main clutch and the PTO and PTI clutches respectively through a directional valve and can realize the oil circuit switching between them, and can ensure the interlocking logical relationship.The box body is composed of four parts: upper, upper middle, lower middle, and lower. The input and main output are arranged vertically and eccentrically, and the input and auxiliary input and auxiliary output are also arranged vertically and eccentrically. The oil distributor of the adjustable pitch propeller is installed on the gearbox, and its oil distribution shaft passes through the middle of the output shaft of the gearbox.

This technology arranges the PTO and PTI clutches in series. When the PTO clutch is engaged, the shaft generator can be used to generate electricity; when the PTI clutch is engaged, the shaft generator is used as an engine. When the main engine fails, the function of emergency return of the ship can be realized, and the function of power assistance can be realized when the ship encounters wind and waves.

This technology can enable the ship to achieve the following six working states: stop, sail, sail + PTO power generation, PTO power generation, PTI emergency return, sail + PTI power assistance. The gearbox not only has high reliability, but also can keep the ship in the best working state through the adjustable pitch propeller.

This technology is specially used with adjustable pitch propellers, with a reduction ratio range of 2:1 to 6:1. The rated input transmission capacity of the gearbox is 3.448kw/rpm, and it can withstand the push and pull force of the propeller of 450KN. It is used for multi-purpose work boats and ocean fishing vessels. Compared with products with the same function, this gearbox has a large transmission capacity, a large speed ratio range, and the functions of auxiliary power output and auxiliary power input. It has advanced indicators, low cost and high reliability, and can achieve multiple working states.

Implementation Methods

The following is an introduction to the present technology in conjunction with the accompanying drawings: As shown in the accompanying drawings I and II, the present technology mainly includes a housing, and an input shaft oil cylinder is installed in the housing through a bearing. One end of the input shaft oil cylinder (2) is connected to the power through an input flange (1) and a high elastic coupling, and the other end of the input shaft oil cylinder is connected to the main clutch (5). The main clutch (5) is supported by a bearing (3) and a bearing (6). The main clutch is connected to the transmission shaft gear (7) through an interference fit key, and the transmission shaft gear (7) is meshed with the output gear (15) on the output shaft; the gear (4) sleeved on the clutch is meshed with the gear (19) sleeved on the auxiliary transmission shaft, and an auxiliary output clutch and an auxiliary input clutch are arranged on the auxiliary transmission shaft, and are fixedly connected to the output flange; an auxiliary input gear is also sleeved on the auxiliary shaft, which is meshed with the transmission gear (9) fixedly connected to the transmission shaft.