Site News  |   Monitor Keywords  |   Monitor Archive  |   Organizer  |   Account Info  |

Marine propulsion shift control

Marine propulsion shift control description/claims

This application claims the benefit of the priority of U.S. Provisional Application Ser. No. 60/480,429, filed Jun. 20, 2003, the entire contents of which are hereby incorporated by reference.

The present invention relates to a method and apparatus for controlling transmission shifts in a marine propulsion system.

Marine vessels in use today use marine propulsion systems that typically include the following sub-systems: an engine to provide power, a transmission to transfer drive power to a propeller, and a control system to provide control of engine speed and transmission engagement. An operator or pilot of the vessel nominally has control of the engine speed and transmission shifting through one or more operator controls. Using these operator controls, the transmission can be shifted between forward and reverse, usually through a neutral (transmission disengaged) position, and the engine speed can be set as desired by the operator.

Engine stalling is a problem sometimes encountered when operating a marine vessel, and often this occurs when the vessel is moving in one direction at high speed and the operator suddenly shifts the transmission into the opposite gear. The stall is the result of the linear momentum of the vessel moving through the water which imparts a drag load on the propeller that tends to keep the propeller, transmission, and engine rotating in the same direction. Reversing the transmission under these circumstances, however, places a sudden increased load on the engine because of the drag load on the propeller. As a result, the engine is often unable to overcome the sudden increased load and, therefore, the engine stalls.

Another problem can arise when a pilot attempts to avoid the engine stalling problem. Faced with a potential engine stall, a pilot will often “race” the engine prior to shifting it into the reverse gear. Racing the engine, however, can lead to transmission clutch damage caused by excessive engine speed prior to full engagement of the transmission clutch to the engine. To avoid damage to the transmission, marine transmission manufacturers recommend maximum acceptable engine speeds (typically 1,000 RPM) for all transmission shifts including neutral to forward or reverse, and forward or reverse through neutral to the opposite gear. Exceeding the maximum acceptable engine speed during a shift tends to result in excessive clutch temperatures and possibly clutch failure.

Attempts to alleviate the above problems usually involve using electronic controls, or “blind timers”, to delay the time between shifting the transmission and increasing of the speed of the engine to allow the transmission clutch to fully engage the engine and propeller driveshaft. This method is only effective under specific conditions, such as where the drag load on the propeller decreases by a sufficient amount during the time delay such that the engine can overcome the sudden increased load without stalling. In some instances, however, this method may be ineffective because the shift is not delayed long enough and the engine stalls, or because the delay is too long resulting in an unnecessarily long shift delay.

In accordance with one aspect of the present invention, there is provided a method of controlling a marine vessel transmission to shift the transmission from an initial gear position to an opposite gear position. A request to shift the transmission from the initial gear position into the opposite gear position is received, engine speed and transmission fluid pressure is measured, and a transmission shift sequence is carried out using the measured engine speed and transmission fluid pressure.

In accordance with another aspect of the invention, there is provided a control system for controlling a marine engine and marine transmission. The control system includes a control module having a controller, a transmission fluid pressure sensor coupled to the controller to provide a transmission fluid pressure signal, and an engine speed sensor coupled to the controller to provide an engine speed signal. The controller is operable to control shifting of the transmission between forward and reverse gears using the engine speed signal and transmission fluid pressure signal.

In accordance with a further aspect of the invention, there is provided a marine propulsion system including an engine, a transmission coupled to the engine by a clutch to permit selective engagement and disengagement with the engine, and a propulsion unit coupled to the transmission. A controller is provided in communication with the engine and the transmission. An operator input device includes a position sensor that is coupled to the controller to permit an operator to input a transmission shift request. The transmission further includes a transmission shift actuator coupled to the controller to receive shift commands from the controller, and also includes a transmission fluid pressure sensor coupled to the controller. The engine includes an engine speed actuator coupled to the controller to receive speed commands from the controller, and further includes an engine speed sensor coupled to the controller. In response to receiving a transmission shift request from the operator input device, the controller determines one or more shift commands using signals from the sensors and sends the shift command(s) to the transmission shift actuator to thereby provide a controlled shifting of the transmission in a manner that reduces wear to the clutch and avoids engine stalls.

Preferred exemplary embodiments of the invention will hereinafter be described in conjunction with the appended drawings, wherein like designations denote like elements, and wherein:

FIG. 1 is a block diagram of a marine propulsion system;

FIG. 2 is a flow and state diagram showing an algorithm for a marine transmission shift from forward to reverse, or vice-versa; and

FIG. 3 is a graphical representation of a transmission shift including time vs. commanded engine speed, actual engine speed, and transmission fluid pressure.

• Provisional Patent
• Utility Patent

• What Is a Patent?
• What Is a Trademark or Servicemark?
• What Is a Copyright?
• Patent Laws