System and method for controlling a multi-speed transmission on a marine engine

1. A method for controlling a multi-speed transmission for an engine powering a marine propulsion device on a marine vessel, the method being carried out by a control module and comprising:

determining a load on the engine;

determining a speed of the engine;

determining a pitch of the marine vessel; and

switching between a first gear ratio and a second gear ratio of the transmission based on the engine load, the engine speed, and the vessel pitch;

wherein the first gear ratio is higher than the second gear ratio, and further comprising switching from the second, lower gear ratio to the first, higher gear ratio in response to determining the following:

the engine load is less than a predetermined engine load threshold;

the engine speed is less than a predetermined engine speed threshold; and

the vessel pitch is less than a predetermined minimum vessel pitch threshold.

2. The method of claim 1 , further comprising:

determining an operator demand on the engine; and

switching between the first gear ratio and the second gear ratio based on the engine load, the engine speed, the vessel pitch, and the operator demand.

3. The method of claim 1 , further comprising:

estimating a slip of a propeller of the marine propulsion device; and

switching between the first gear ratio and the second gear ratio based on the engine load, the engine speed, the vessel pitch, and the propeller slip.

4. The method of claim 3 , further comprising estimating the propeller slip based on a speed of the marine vessel, a pitch of the propeller, and a value of at least one of the first gear ratio and the second gear ratio.

5. The method of claim 1 , further comprising:

determining an operator demand on the engine;

estimating a slip of a propeller of the marine propulsion device; and

switching between the first gear ratio and the second gear ratio based on the engine load, the engine speed, the vessel pitch, the operator demand, and the propeller slip.

6. The method of claim 1 , further comprising switching from the first, higher gear ratio to the second, lower gear ratio in response to determining the following:

the engine load is greater than the predetermined engine load threshold;

the engine speed is greater than the predetermined engine speed threshold; and

the vessel pitch is within a predetermined vessel pitch window.

7. The method of claim 6 , wherein the vessel pitch window encompasses vessel pitch values at which the marine vessel is estimated to be on-plane.

8. The method of claim 1 , wherein the marine vessel is estimated to be off-plane at vessel pitch values less than the predetermined minimum vessel pitch threshold.

9. The method of claim 1 , wherein the marine propulsion device is one of multiple marine propulsion devices on the marine vessel;

wherein the multiple marine propulsion devices are operable in an engine speed sync mode, in which an engine of each marine propulsion device is operated at the same engine speed; and

further comprising disabling the engine speed sync mode while switching between the first gear ratio and the second gear ratio.

10. A marine propulsion system for a marine vessel, the marine propulsion system comprising:

an engine;

a propeller configured to be coupled in torque-transmitting relationship with the engine;

a transmission configured to transmit torque from the engine to the propeller at one of at least a first gear ratio and a second gear ratio;

an engine speed sensor measuring a speed of the engine;

a vessel pitch sensor measuring a pitch of the marine vessel; and

a control module in signal communication with the engine speed sensor and the vessel pitch sensor;

wherein the control module causes the transmission to switch between transmitting torque at the first gear ratio and transmitting torque at the second gear ratio based on a load on the engine, the engine speed, and the vessel pitch; and

wherein the control module causes the transmission to transmit torque at the first gear ratio in response to the vessel pitch indicating that the marine vessel is off-plane, and causes the transmission to transmit torque at the second gear ratio in response to the vessel pitch indicating that the marine vessel is on-plane;

wherein the first gear ratio is higher than the second gear ratio, and wherein the control module causes the transmission to switch from transmitting torque at the second, lower gear ratio to transmitting torque at the first, higher gear ratio in response to determining the following:

the engine load is less than a predetermined engine load threshold;

the engine speed is less than a predetermined engine speed threshold; and

the vessel pitch is less than a predetermined minimum vessel pitch threshold, below which the marine vessel is estimated to be off-plane.

11. The marine propulsion system of claim 10 , wherein the control module causes the transmission to switch from transmitting torque at the first, higher gear ratio to transmitting torque at the second, lower gear ratio in response to determining the following:

the engine load is greater than the predetermined engine load threshold;

the engine speed is greater than the predetermined engine speed threshold; and

the vessel pitch is within a predetermined vessel pitch window encompassing vessel pitch values at which the marine vessel is estimated to be on-plane.

12. The marine propulsion system of claim 11 , wherein the control module causes the transmission to switch from transmitting torque at the first, higher gear ratio to transmitting torque at the second, lower gear ratio in response to determining that the vessel pitch has been within the vessel pitch window for longer than a predetermined period of time.

13. The marine propulsion system of claim 10 , further comprising an operator input device for inputting an operator demand on the engine to the control module;

wherein the control module causes the transmission to switch between transmitting torque at the first gear ratio and transmitting torque at the second gear ratio based on the engine load, the engine speed, the vessel pitch, and the operator demand.

14. The marine propulsion system of claim 13 , wherein the operator input device is a throttle lever.

15. The marine propulsion system of claim 10 , further comprising a vessel speed sensor providing a speed of the marine vessel to the control module;

wherein the control module estimates a slip of the propeller based on the vessel speed, a pitch of the propeller, and a value of at least one of the first gear ratio and the second gear ratio; and

wherein the control module causes the transmission to switch between transmitting torque at the first gear ratio and transmitting torque at the second gear ratio based on the engine load, the engine speed, the vessel pitch, and the propeller slip.

16. The marine propulsion system of claim 10 , further comprising:

an operator input device for inputting an operator demand on the engine to the control module; and

a vessel speed sensor providing a speed of the marine vessel to the control module;

wherein the control module estimates a slip of the propeller based on the vessel speed, a pitch of the propeller, and a value of at least one of the first gear ratio and the second gear ratio; and

wherein the control module causes the transmission to switch between transmitting torque at the first gear ratio and transmitting torque at the second gear ratio based on the engine load, the engine speed, the vessel pitch, the operator demand, and the propeller slip.

17. The marine propulsion system of claim 10 , further comprising an engine load sensor providing the engine load to the control module;

wherein the engine load sensor comprises one of a pressure sensor sensing a pressure of air in an intake manifold of the engine and a throttle valve sensor measuring a position of a throttle valve of the engine.

18. The marine propulsion system of claim 10 , wherein the vessel pitch sensor is an inertial measurement unit.

19. A method for controlling a multi-speed transmission for an engine powering a marine propulsion device on a marine vessel, the method being carried out by a control module and comprising:

determining a load on the engine;

determining a speed of the engine;

determining a pitch of the marine vessel; and

switching between a first gear ratio and a second gear ratio of the transmission based on the engine load, the engine speed, and the vessel pitch;

wherein the marine propulsion device is one of multiple marine propulsion devices on the marine vessel;

wherein the multiple marine propulsion devices are operable in an engine speed sync mode, in which an engine of each marine propulsion device is operated at the same engine speed; and

further comprising disabling the engine speed sync mode while switching between the first gear ratio and the second gear ratio.