Many sailboats are provided with auxiliary power, to power the sailboat when it is not feasible for the boat to be under sail or when additional power is needed, e. g., under low wind or heavy sea conditions. Generally, the sailboat is provided with a low horsepower (typically less than 100 hp) inboard engine for this purpose, associated with a propeller which turns in the water to drive the boat.

The propeller may (1) have a relatively large diameter so that the water resistance it encounters causes it to have to rotate at a lower speed than the speed of the engine at full throttle, or (2) have a relatively small diameter so that at full throttle the propeller encounters sufficiently low water resistance that it is capable of transmitting the full horsepower of the engine.

In the first instance, full power can be obtained when required, but a relatively high engine speed is necessary in order to maintain an acceptable propeller horsepower for cruising, generating vibration that results in engine wear and noise.

In the second instance, the engine can be run at relatively slow speed and still produce sufficient propeller horsepower for cruising conditions. At these slow engine speeds, the vibration of the engine and thus the noise and wear generated are relatively minimal.

However, this propeller/engine combination will not be capable of providing full power during an emergency situation, e. g., a severe storm, potentially resulting in

damage to the boat and/or injury to the operator should the boat be unable to reach a safe harbor.

To address these problems, some sailboat engines are provided with variable pitch propellers which allow the position of the propeller relative to the water to be varied to vary the water resistance against the propeller. By varying the water resistance against the propeller, this has the same effect as would varying the diameter of the propeller, as described above. These variable pitch propellers are generally relatively expensive and may tend to be unreliable.

Summary of the Invention The invention features an auxiliary power supply system to provide power to a boat having a primary power supply, e. g., a sailboat. The system includes (a) an inboard marine engine having less than 100 hp, (b) a propeller dimensioned and positioned to turn in the water and propel the boat, (c) a propeller shaft on which the propeller is mounted, and (d) a transmission having an input shaft in torque transmitting engagement with the engine and having an output shaft in torque transmitting engagement with the propeller shaft. The transmission has a plurality of discrete forward gears, or, alternatively, is a continuously variable transmission.

Each forward gear provides a different reduction ratio, i. e., ratio of engine speed to propeller speed.

By providing a plurality of forward gears, the operator of the boat can shift between gears having different reduction ratios, changing the relationship of propeller horsepower to engine speed (described above in the context of propeller diameter or pitch) while the boat is in motion. Advantageously, this can be accomplished without changing the size or pitch of the

propeller; the reduction ratio is changed mechanically by the transmission.

The diameter of the propeller is preferably selected to allow the propeller to receive the full horsepower of the engine shaft when the propeller is in its normal position in the water, the reduction ratio is 1: 1, and the engine is at full throttle. In this case, the transmission may include a first,"economy"gear in which the reduction ratio is 1: 1, so that the full engine power can be transmitted to the propeller when cruising in calm seas, and a second,"power"gear in which the reduction ratio is reduced so that the engine can turn more slowly while still maintaining sufficient propeller speed to make forward progress (e. g., for use in emergency conditions or rough seas). Thus, the engine can be operated in"economy"gear under most conditions, for fuel economy and reduced engine wear, but will have sufficient power in"power"gear to operate under more severe conditions.

In preferred embodiments in which the transmission includes a plurality of discrete gears, the transmission includes a manual shift lever to allow the operator of the boat to shift between gears. In other embodiments, the transmission is continuously variable so that the reduction ratio is substantially optimal at all times.

In another aspect, the invention features a power supply system to provide power to a boat including: (a) an inboard marine engine; (b) a propeller dimensioned and positioned to turn in the water and propel the boat; (c) a propeller shaft on which the propeller is mounted; and (d) a transmission having an input shaft in torque transmitting engagement with the engine and an output shaft in torque transmitting engagement with the propeller shaft. The transmission includes: (i) a plurality of sets of planetary gears in torque

transmitting relation with the output shaft; (ii) a plurality of selectively engageable forward gears, each forward gear being disposed in torque transmitting engagement with a corresponding one of the sets of planetary gears to be capable of driving the corresponding set of the planetary gears when engaged; (iii) a forward shifting mechanism for selectively engaging the forward gears; (iv) a reverse gear selectively engageable with the output shaft in torque transmitting relation; and (v) a reverse shifting mechanism for selectively engaging the reverse gear.

Preferred embodiments include one or more of the following features. The power supply system includes a pair of shift levers constructed to be moveable by a user to operate the forward shifting mechanism (the mechanism that shifts between the economy and power gears) and the reverse shifting mechanism (the mechanism that shifts between the forward, neutral, and reverse), respectively.

The power supply system includes a locking mechanism constructed to prevent a user from operating both shift levers simultaneously. The locking mechanism includes a camming mechanism associated with each shift lever and a lock member positioned between the two levers so that movement of one of the shifting levers causes movement of the lock member by the camming mechanism associated with that shift lever into interference with a portion of the other shift lever preventing movement of the other shift lever. The transmission includes two forward gears and the forward shifting mechanism includes a forward shifting fork that is moveable between a first position in which it engages one of the forward gears and a second position in which it engages the other of the forward gears, and a camming mechanism constructed to cause movement of the forward shifting fork between its first

and second positions in response to movement of the first shift lever.

The invention further features boats that include the auxiliary power system of the invention. The auxiliary power system of the invention is particularly suitable for use in displacement vessels, i. e., vessels that move through the water rather than planing over the surface of the water, more particularly sailboats.

Other features and advantages of the invention will be apparent from the Description of the Preferred Embodiments thereof, and from the claims.

Brief Description of the Drawings Fig. 1 is a schematic side view, in partial cross- section, of a sailboat including an auxiliary power supply system according to one embodiment of the invention. Figs. la and lb are schematic side views, in partial cross-section, of sailboats including an auxiliary power supply of the invention, illustrating different possible relative configurations of the engine, transmission, and propeller shaft.

Figs. 2 and 2a are perspective views of a transmission according to one embodiment of the invention with and without its housing, respectively. Fig. 2b is a side view of the transmission with its housing, showing the shift levers used to operate the transmission (not shown in Figs. 2 and 2a) in detail. Fig. 2c is a partial side view of the transmission without its housing, showing a portion of the shifting mechanism in detail.

Fig. 2d is a partial top view, in partial cross-section, of the transmission without its housing.

Figs. 3 and 3a are exploded perspective views of the transmission of Fig. 2, without its housing, taken from the same direction as Fig. 2 and the opposite direction, respectively.

Fig. 4 is a cross-sectional view of the transmission of Fig. 2 taken along line 4-4.

Figs. 5 and 5a are detail views of the shift mechanism for the forward and reverse forks, respectively.

Figs. 6 and 6a are detail side and rear views, respectively, of the range trunion used in the transmission of Figs. 2-4.

Figs. 7 and 7a are detail views of a camming shift collar used in the transmission of Figs. 2-4.

Description of the Preferred Embodiments Applications Referring to Fig. 1, a sailboat 10 includes a preferred auxiliary power system 12. Auxiliary power system 12 includes an inboard engine 14 adapted to drive a propeller shaft 16 having a propeller 18 mounted at its end. Propeller 18 is positioned in the water at a suitable angle to drive the boat forward when it is rotated at sufficient speed, as is well known in the art.

Interposed between engine 14 and propeller shaft 16 is transmission 20. Transmission 20 can be any type of transmission desired, so long as it provides more than one reduction ratio.

In Fig. 1, the drive shaft of engine 14 and propeller shaft 16 are substantially coaxial. Figs. la and lb illustrate two alternative engine/propeller shaft configurations,"down angle drive"and"v-drive", respectively. In the"down angle drive"configuration, the propeller shaft is disposed at an angle with respect to the engine drive shaft, typically about 5-15°. In the "v-drive"configuration, the engine drive shaft and propeller shaft form a"v", i. e., the engine faces in the opposite direction to the direction shown in Fig. 1. The same transmission mechanism can be used with each of

these configurations, with minor modifications, as would be understood by one skilled in the art. The transmission described hereinbelow with reference to Figs. 2-4 is suitable for use in the configuration shown in Fig. 1.

While any desired type of transmission may be used, and in some applications a transmission having more than two gears, or a continuously variable transmission may be preferred, a two-speed transmission is illustrated in Figs. 2-4 and described below to provide a simple example of a suitable transmission.

Torque Transmission Paths The manner by which torque is transmitted from the input shaft of the engine to the output shaft of the transmission when the transmission is in the forward (high or low) and reverse gears, respectively, will first be described below.

Forward Torque Transmission Path Figs. 2 and 2a show the assembled transmission 30, with and without its housing 32. Transmission 30 includes an input shaft 34 for receiving torque from a engine, and an output shaft 52 that is connected to a flange 36 for connection in torque-transmitting relation to a propeller shaft (not shown).

As shown in Fig. 3, input shaft 34 drives an input gear 36 which rotates in the direction of the engine shaft ("direction A", see arrow in Fig. 3). Input gear 36 in turn drives a main gear 38 which causes forward shaft 40 to rotate in the opposite direction ("direction B"). On shaft 40 are mounted first and second forward gears 42,44. Until they are operably engaged, first and second forward gears 42 and 44 are not driven by shaft 40, because these gears have no teeth on their inner surface, and they are positioned on portions of the shaft

that have no teeth. First and second forward gears are selectively operably engaged by translational movement of forward shifting fork 56 (arrows S), as will be explained further below. Forward shifting fork 56 has an annular portion 57 that includes a toothed inner cylindrical surface 58. When the transmission is assembled, toothed surface 58 engages spline surface 60 (Fig. 3a) of shaft 40, causing shaft 40 to drive annular portion 57 of shifting fork 56 in direction B. Annular portion 57 includes raised portions 59 on each of its faces, dimensioned and positioned for torque transmitting engagement with corresponding raised portions 61 on the facing portions of the first and second forward gears 42, 44. When the raised portions 59 on the shifting fork engage the corresponding raised portions 61 on one of gears 42 or 44, the thus-engaged gear is then turned in direction B by the annular portion.

When the transmission is assembled, first forward gear 42 fits between and engages a set of planetary gears 48 (see Fig. 3a) and second forward gear 44 fits between and engages a second set of planetary gears 49. The first and second sets of planetary gears are mounted on common shafts, such that when one of the sets is engaged and turned the other set will turn as well. If either the first or the second forward gear is operably engaged, the forward gear that is engaged will turn the planetary gears in direction A. Planetary gears 49 in turn fit within and engage the inner toothed surface 50a of output gear 50, driving the output flange 36, and thus the propeller shaft (not shown) in the same direction that the planetary gears are turned, i. e., direction A.

If, on the other hand, neither of forward gears 42 and 44 are engaged, the transmission may either be in neutral (no gears are engaged and the output shaft does

not rotate) or in reverse (the output shaft rotates in direction B).

Reverse Torque Transmission Path The transmission is in reverse when reverse gear 54 is operably engaged. Like the forward shifting fork, reverse shifting fork 62 includes a toothed inner cylindrical surface 64 that engages spline surface 66 of shaft 55, and annular portion 68 of the reverse shifting fork includes raised portions 70 (Fig. 3a) dimensioned and positioned to engage corresponding raised portions 72 (Fig. 3) on reverse gear 54. When the corresponding raised portions are engaged, reverse gear 54 will be turned by the annular portion 68 in the same direction as shaft 55. In this case, reverse gear 54 is driven by reverse shaft 55 (extending from, and coaxial with, input shaft 34), in direction A. The teeth of reverse gear 54 in turn engage the outer toothed surface 50b of output gear 50, causing output gear 50 to turn in direction B.

Shifting Mechanisms The mechanisms which allow the transmission to be shifted between the forward, neutral and reverse gears, and, in forward, between high and low gear, will be explained below.

Locking Mechanism As shown in Fig. 2b, the transmission is shifted by an operator by rotating range lever 83, which causes rotation of range trunion 82, and/or shift lever 85, which causes rotation of shift trunion 84. The range of motion of the range and shift levers is indicated by the heavy, dark lines in Fig. 2b. As shown, the levers are positioned close together, so that they interfere with each other, preventing a user from shifting the range

lever into"hi"when the shift lever is in the"reverse" position.

The transmission also includes a"locking" mechanism which prevents the operator of the transmission from rotating both levers at once (an action which could damage the transmission). This locking mechanism is shown in Fig. 2d. Each of the range and shift trunions includes spaced depressions 86 (the range trunion includes two such depressions, as shown in Fig. 6a, positioned to correspond to the position of the trunion when the range lever is shifted to"hi"and"low", while the shift trunion includes three depressions, positioned to correspond to the position of the trunion when the shift lever is shifted to"forward","neutral"and "reverse"). Two balls 88 are disposed between the two trunions in a bore 90 that has a diameter slightly greater than the diameter of the balls. When the transmission is engaged in any gear, the two balls are forced apart into the depressions 86 that correspond to that gear by a spring 92 disposed in the bore 90 between the two balls, as shown in Fig. 2d. When either of the trunions is rotated between gears, the ball on that side of the bore 90 is forced out of the depression 86 and displaced toward the other ball. The displaced ball then contacts a pin 94 that is interposed between the two balls in the bore. Pin 94 is dimensioned so that, when either of the balls is displaced toward the other in this manner, the ball will be forced against the pin 94 and will force the pin against the other ball, creating an interference fit. This interference fit prevents the other ball from being displaced from its depression, thus preventing the other trunion from being rotated, until the first trunion is engaged in a gear and its ball is biased by the spring into the depression corresponding to that gear.

Forward-Neutral-Reverse Shifting Mechanism The transmission can be shifted between forward, neutral and reverse by rotation of shift lever 85.

Rotation of shift lever 85 causes rotation of shift trunion 84, during which the angled toothed portion 100 of shift trunion 84 engages angled pinion gear 102 of actuation rail 95, resulting in rotation of actuation rail 95 (see Figs. 2d and 3).

Rotation of actuation rail 95 in turn rotates camming shift cam 104 (shown in detail in Figs. 7 and 7a), which is splined onto actuation rail 95. This rotation of camming shift cam 104 has several effects.

First, rotation of the camming shift cam 104 results in translational movement of reverse shifting fork 62 which is mounted in the housing for reciprocal movement, as shown in Fig. 2c. Translation of reverse shifting fork 62 also causes translation of forward- reverse shift rail 96 on which the shifting fork is rigidly mounted (e. g., by a bolt 98). The translational movement of the reverse shifting fork and its shift rail is the result of sliding movement of cam follower 108 of reverse shifting fork 62 within a J-shaped camming groove 106 in shift cam 104 (shown in Fig. 7a) in which cam follower 108 is slidably engaged. (When the reverse shifting fork reaches the bottom of the camming groove, it is caused to move in the direction of the curve in the camming groove.) The reverse shifting fork is thus translated between a position in which the reverse shifting fork is operably engaged, as discussed above, and a position (corresponding to neutral) in which the reverse shifting fork is not operably engaged.

Second, rotation of the camming shift cam 104 causes wedge 110 of the shift cam 104 to rotate in and out of engagement with groove 112 of forward shift lock 114 (see Fig. 2c, in which the wedge and groove are

engaged). When the wedge and groove are not engaged, the transmission is in whichever forward gear is selected, as discussed below. This locking device is provided to hold the reverse shifting fork and its associated components in a fixed position when not in use. Because forward shift lock 114 is rigidly mounted on forward shift rail 116, when the wedge and groove are engaged, as shown in Fig. 2c, reciprocal movement of forward shift rail 116 is prevented, holding the forward-neutral-reverse shifting mechanism in neutral.

Hiqh-Low Shifting Mechanism When the forward shift rail 116 is operably engaged, as discussed above, the transmission can be shifted by the operator into either forward-economy or forward-power gear by rotation of range lever 83.

Rotation of range lever 83 causes corresponding rotation of range trunion 82. Range trunion 82 includes an eccentric wedge 118, the preferred shape of which is shown in Fig. 6. Eccentric wedge 118 fits within a groove 120 on range shift collar 122 (see, e. g., Figs. 2c and 2d) so that rotation of the eccentric wedge causes translational movement of range shift collar 122, which results in corresponding translational movement of forward shifting fork 56 from its two positions in which it engages gears 42 or 44, as discussed above.

Other embodiments are within the claims.

For example, although a two-speed transmission has been described, as discussed above any type of transmission may be used. If it is desired to vary the reduction ratio over a continuum, rather than step-wise, a continuously variable transmission may be used. Such transmissions are described in, e. g., U. S. Patent Nos.

4,768,996 and 4,810,234, the disclosures of which are incorporated herein by reference.