Self-steering system for boats

A steering system for a boat includes an auxiliary rudder which is rotatable to effect changes in course of the boat. A servo-pendulum rudder is rotatable by a positioning device. When the servo-pendulum rudder is rotated, it is pivotal transversely to a keel line of the boat by water flowing past the boat. A drive connection is provided between the servo-pendulum rudder and the auxiliary rudder. The drive connection includes a drive member and a driven member. One of the driving and driven members is pivotal between an engaged condition in which the drive connection is effective to transmit force between the pendulum rudder and the auxiliary rudder and disengaged condition in which the drive connection is ineffective to transmit force. The drive and driven members may be provided with teeth which are disposed in meshing engagement when the one of the driving and driven members is in the engaged condition.

BACKGROUND OF THE INVENTION 
The present invention relates to a self-steering system for boats, in 
particular sailing boats. 
Known, generic self-steering systems comprise four main elements, namely a 
positioning device (transducer), a servopendulum rudder, an auxiliary 
rudder and a disengageable drive connection between servo-pendulum rudder 
and auxiliary rudder. Course corrections are effected through said 
disengageable drive connection by the auxiliary rudder as a result of a 
pivoting motion of the servo-pendulum rudder, which is caused to perform a 
pendulum swing by the positioning device. The drive connection can be 
released using the clutch device. Specifically, such a self-steering 
system consists of a servo-pendulum rudder, which can be rotated by means 
of a positioning device such as a windvane or a compass-controlled 
servomotor when the boat deviates from a desired course and which as a 
result of the rotation can be pivoted out transversely to the keel line of 
the boat by water flowing past, an auxiliary rudder, which an be forcibly 
rotated about an approximately vertical axis of rotation as a result of a 
pivoting motion of the servo-pendulum rudder, can be flowed against by 
water flowing past and is used to generate course corrections, and also a 
clutch device for engaging and disengaging the drive connection between 
the servo-pendulum rudder and the auxiliary rudder. 
Problems may be experienced with the drive connection due to possible 
extreme swings of the servo-pendulum rudder and/or possible high forces in 
a seaway. The clutch device itself, which is combined with the drive 
connection, also gives cause for concern for the same reasons. Prior 
solutions have thus failed to provide complete satisfaction. 
In the self-steering system with servo-pendulum and auxiliary rudder known 
from EP-A2-243 942, the releasable drive connection comprises two levers 
carrying joint balls at their free ends and an intermediate Cardan-like 
lever, which accommodates the balls together and has a removable bearing 
surface for releasing one of the two balls, i.e. for disengaging the drive 
connection. This drive connection thus consists of two knuckle joints, 
active in the working position along two or three axes, which, although 
providing a relatively low-play drive connection, demand a certain agility 
during engaging and disengaging and also require a hand to be placed 
directly on the double-jointed connection during engaging and disengaging. 
This proximity of the hand to the moving parts entails a risk of injury. 
Furthermore, the joint sockets of the intermediate lever are subject to a 
not inconsiderable risk of breakage in the case of impulsive movements of 
the servo-pendulum rudder or of the auxiliary rudder. 
In another known self-steering system with servo-pendulum rudder and 
additional auxiliary rudder based on G-U1-88 10 313.3, the releasable 
drive connection between servo-pendulum rudder and auxiliary rudder 
consists of a tiller for operating the auxiliary rudder, which tiller 
encloses a windvane mounting shaft in the manner of a frame, can pivot 
vertically and rests with a U shaped recess on a horizontally oriented 
finger, said finger protruding laterally from the upper end of the 
servo-pendulum rudder above the pendulum axle of the latter and thus 
transmitting the pendulum motion of the servo-pendulum rudder to the 
frame-like tiller of the auxiliary rudder. The force transmission finger 
moves along a circular path in the vertical plane, so the joint for 
vertically pivoting the auxiliary rudder tiller has to be very smooth 
running to follow every pendulum swing of the servo-pendulum rudder 
horizontally and vertically. Only thus can it be ensured that the 
frame-like tiller, also referred to as the driving yoke, always remains in 
positive-locking contact with the force transmission finger of the 
servo-pendulum rudder. Although such a drive connection offers a degree of 
remote operation and thus limits the risk of injury during engaging and 
disengaging, it also allows a not inconsiderable amount of mechanical 
play, which has a detrimental effect on responsiveness. Furthermore, the 
rudder travel is severely restricted by the frame construction of the 
tiller and the functional reliability when transmitting relatively high 
forces and/or relatively frequent pendulum movements gives cause for 
concern. 
SUMMARY OF THE INVENTION 
Against the background of this prior art the object of the present 
invention is to improve the handling and operational reliability of the 
clutch device. Moreover it is desired to accommodate the possible extreme 
loads on the drive connection in a more satisfactory manner. 
The invention proposes a self-steering system with the features of claim 1 
in solution of this object. Accordingly in a generic self-steering system 
(i) the drive connection between the servo-pendulum rudder and the 
auxiliary rudder comprises a toothed bevel gear or a similar joint-free 
angular drive connection and (ii) the drive member or, preferably, the 
driven member, of the clutch device is or becomes secured in place in both 
positions. The drive member or the driven member is preferably in the form 
of a rocker that can be pivoted about its rocker axis between the working 
position, that is to say the engaged state, and the resting position, that 
is to say the disengaged state. 
The invention, in particular with a toothed bevel gear element (drive 
member or driven member) realized as a rocker, allows even large and 
impulsive forces to be transmitted operationally reliably almost without 
wear and with a precisely pre--definable margin for play, and at the same 
time also allows the operator to engage and disengage the self-steering 
system, even when the latter is fully loaded, without serious risk of 
injury. It thus even allows safe operation when, for example, the boat 
equipped with the self-steering system is making little way through a 
sloppy sea and the servo-pendulum rudder is subject to sudden lateral 
impulses which load the drive connection and generally also set it in 
motion. The self-steering system can likewise also be safely engaged and 
disengaged when the boat is making good way despite the high dynamic loads 
that occur at speed. This is of particular benefit when, for example, it 
becomes necessary to disengage in order to make a sudden avoiding 
maneuver. 
A rocker according to the invention represents a particularly advantageous 
way of allowing the operator to keep the operating hand sufficiently far 
away from the actual drive connection when carrying out the engaging 
operation. A handle, such as an auxiliary steering tiller or the like, may 
for example by provided for carrying out the rocker movement. Moreover the 
rocker, i.e. the movable drive or driven member, can be secured in place 
particularly effectively, that is to say to quickly and with strength for 
force transmission, with simple means and without compromising the 
necessary margin for play. 
Executing the joint-free drive connection as a bevel gear, as is 
particularly preferred, allows said drive connection to be free of slip, 
capable of withstanding high mechanical loads and also particularly free 
of wear. Since the lateral swings, i.e. pendulum swings, of the 
servo-pendulum rudder do not exceed approximately +/-30.degree. in normal 
operation, or at least only exceed this range in exceptional cases, the 
toothed bevel gear can, as is particularly preferred, be in the form of 
toothed segments of a circle. This advantageously allows the drive 
connection to separate in the event of extreme servo-pendulum rudder 
pendulum swings in order to avoid the auxiliary rudder being overloaded, 
damaged or forced to make undesirable extreme swings. Moreover, this 
removes the need for maximum travel limiters, so the considerable forces 
that can occur at such stops are avoided and the self-steering system 
components affected can consequently be of lightweight design. 
The arrangement of the rocker at the head of the auxiliary rudder shaft, 
especially on center, is particularly advantageous, as it makes the rocker 
particularly easily accessible for the engaging operation and considerably 
simplifies the design of the drive connection. 
Expedient configurations of the subject matter of the invention, which in 
particular ensure high operating convenience, in particular also one-hand 
operation, and high mechanical strength, low-play connection, few 
components, high operating reliability and a particularly low risk of 
injury, may be found in the remaining claims. 
The components mentioned above, claimed and described in the exemplary 
embodiment that are to be used according to the invention are not subject 
to any particular special requirements with respect to their dimensions, 
shape, choice of materials and technical design, so the selection criteria 
known in the respective area of application may be applied without 
restriction.

DESCRIPTION OF SPECIFIC PREFERRED EMBODIMENT 
FIG. 1 shows a self-steering system 100 having a servo-pendulum rudder 10, 
an auxiliary rudder 20, a positioning device 30 (transducer) with a 
windvane 31 and an engageable and disengageable drive connection 40 
between the servo-pendulum rudder and the auxiliary rudder. 
In the event of a deviation from the desired course, that is to say, in the 
case of the embodiment shown and to this extent preferred, a deviation of 
the actual angle of incidence from the prescribed angle of incidence SK 
between apparent wind direction and heading K of the boat B, the air flow 
streaming past flows against the windvane with a lateral component, thus 
causing the windvane to move out of its vertical neutral position shown in 
FIG. 1. This movement W of the windvane 31 is transmitted in a motion of 
rotation R of the servo-pendulum rudder shaft 11 about the latter's axis 
of rotation 12 to the servo-pendulum rudder blade 13, which is in the 
water, by means of a connecting rod 32 and a linkage protected by a 
housing 33. The servo-pendulum rudder blade is thus turned out of its 
neutral position, shown in FIG. 1, essentially parallel to the keel line K 
of the boat B and experiences a transverse force to the starboard or port 
side of the boat. The servo-pendulum rudder blade gives in response to 
this transverse force component because the servo-pendulum rudder arm 14 
is mounted in a pendulum arm holder 19 such that it can pivot (P) about a 
horizontal or slightly inclined stationary pendulum axle in one bearing 
region 16 or in two bearing regions 16 spaced apart from each other. The 
pendulum axle is provided on a cantilever bolt 17 that is (indirectly) 
fastened rigidly to the boat. 
The pendulum arm 14 extends in two directions, the lower lever arm 14A 
taking the form of a quadrant segment in order to accommodate the 
servo-pendulum shaft bearing and the bearing on the cantilever bolt 17 at 
right angles to each other, and the second, upwardly angled lever arm 14B 
bearing the drive member of the drive connection 40 to the auxiliary 
rudder 20 at its upper free end (FIG. 8A/B). In the exemplary embodiment 
shown and to this extent preferred, this free end of the lever arm 14B has 
a 90.degree. segment of a circular toothed bevel gear. This drive member 
41 is advantageously fastened at the upper free end of the pendulum arm 14 
in such a way that the summit of the toothed bevel gear 42 represents the 
uppermost end of the respective lever arm 14B. The teeth will mesh through 
pendulum swings covering an angular range of +/-30.degree.. 
Along the line of the imaginary extension of the cantilever bolt 17 to the 
stern S of the boat B can be found a supporting structure 21, which bears 
both the auxiliary rudder 20 and the cantilever bolt 17 and thus the 
servo-pendulum rudder 10 together with the positioning device 30, which is 
fastened to the cantilever bolt 17 in a rotationally-fixed manner. On its 
side remote from the cantilever bolt 17 the supporting structure 21 can be 
fastened by means of a mounting element 22 to the stern S of the 
respective boat B. 
The supporting structure 21, directly or indirectly, allows the shaft 23 of 
the auxiliary rudder 20 to be mounted, free to rotate, in an approximately 
vertical position. The auxiliary rudder shaft 23 protruding at its upper 
end above the supporting structure 21 or ending at the latter has a 
rotatory force transmission component 25 in order to transmit the motion 
of rotation of a driven member 43 borne by said component 25 to the 
auxiliary rudder shaft 23 with axis of rotation 24. The self-steering 
system described thus far, with the exception of the toothed bevel gear 
42, is known from the Applicant's EP-A1-0 243 942. There is thus no need 
to provide any further detail on the function of the individual elements, 
reference being made in this respect to EP-A1-0 243 942. As can be seen in 
detail in FIGS. 2 to 8A/B, the driven member 43 comprises a rocker 
pivotable through an angle of approximately 15 to 20.degree. about a 
horizontal rocker axis 44 aligned approximately perpendicular to the keel 
line K of the boat B in the zero position. The rocker leg 43A facing aft 
with respect to the boat B bears at its extreme end a 90.degree. segment 
of a toothed bevel gear 45 that meshes with the toothed bevel gear 42 of 
the drive member 41 in the working position of the rocker FIG. 8A. As can 
be seen in FIG. 8A, the toothed bevel gears 42 and 45 are perfectly 
engaged when the approximately horizontal underside (stop 46B) of the 
rocker leg 43A is resting with a stop face 46A on the head 23A of the 
auxiliary rudder shaft 23 such that the angle between them is minimal. 
This precisely defines the mechanical play of the toothed bevel gear 42, 
45. 
The rocker 43 is transferred to the resting position shown in FIG. 8B by 
pivoting it through approximately 15.sub.-- about the rocker axis 44 by 
means of an auxiliary steering tiller 47 that may optionally be capable of 
being fastened in different positions. The underside of the front rocker 
leg 43B rises to the left, i.e. forwards, in the working position and has 
a nose-like conical blocking element 48 formed, for example integrally, on 
its free end. Pivoting the rocker from the working position shown in FIGS. 
1 and 8A into the resting position shown in FIG. 8B inserts the blocking 
element 48 into a conical recess 49, provided on the supporting structure 
21, that serves as the blocking counter. This combination of blocking 
element and blocking counter is provided in case, as is preferred, the 
auxiliary rudder is simultaneously to be held blocked against rotation in 
its neutral position when the rocker is in the resting position, i.e. in 
the disengaged state. In this embodiment the rocker 43 must assume either 
the working position or the blocking position; no other states are 
possible. In the interests of compactness, transmission strength and 
minimum play, the rocker 43 is configured on its underside for a 
positive-locking connection with the head of the auxiliary rudder shaft 23 
in such a way that two recesses 51 (FIGS. 3, 4 and 6) provided parallel to 
the keel line are incorporated in the underside of the rocker so as to 
give the longest possible double lever for transmitting the rotatory 
force. The recesses 51, which can be seen most clearly in FIGS. 3, 4 and 
6, are shaped to conform to hump-like elements 26 (FIGS. 8A/B) provided at 
the head of the auxiliary rudder shaft 23 such that these humps are able 
to engage in the recess 51 with minimum play, but also such that the 
rocker 43 can be pivoted about these humps between the working position 
and the resting position. 
To provide the best possible pivoting mounting the rocker 43 has a bore 
right through its width along the rocker axis 44 (FIGS. 3 and 4) such that 
swivel pins 53, which can be inserted and screwed fast into the bores 52 
from both sides, pass through the recesses 51 such that they coincide with 
the humps on the head of the auxiliary rudder shaft (FIGS. 8A/B). For this 
purpose these humps are drilled through flush with the bores 52 so that 
the swivel pins 53 are accommodated to minimize play. The rocker 43 is 
thus fastened such that it cannot be lost, is free to pivot and can rotate 
together with the auxiliary rudder shaft 23 about the auxiliary rudder 
shaft axis. 
One single retaining element is sufficient to ensure that the rocker 43 is 
effectively secured in its working position and in its resting position. 
This retaining element consists of a one-sided lever arm 54, which is 
fastened in a central position in the head of the auxiliary rudder shaft 
23 and can pivot about an approximately horizontal lateral axis 59 (FIGS. 
1 and 8A/B). This lever arm 54 passes through the central region of the 
rocker 43. Accordingly the rocker 43 has an elongated hole 55 extending 
approximately parallel to the keel line K with the auxiliary rudder 20 in 
the neutral position and being arranged such that the rocker axis 44 
passes approximately through the center of the elongated hole 55. The 
swivel pins 53 thus end close to the wall of the elongated hole so that 
there is space in this region of the elongated hole for the lever arm 54 
to pass through. 
Stop surfaces 56 and 57, arranged inclined towards each other, are provided 
at the upper opening end of the elongated hole 55 to support a clamping 
piece 54B, which is mounted on the lever arm 54 such that it can be 
adjusted along the lever arm 54 using an actuator 58 (FIG. 1). As can be 
seen from FIG. 8A, the lever arm 54, which is limited in its pivoting 
movement by the elongated hole 55, is pivoted about its pivoting axis 59 
into the rearmost position, to the right in the drawing, in the working 
position so that the clamping piece rests against the stop surface 57 and 
holds the rocker 43 in its working position. Releasing the clamping piece 
54B by rotating the actuator 58 about the longitudinal axis of the lever 
arm 54 releases the rocker 43, allowing the lever arm 54 to be pivoted 
forwards (to the left in the drawing) about its pivot axis 59. In this 
position (FIG. 8b) the clamping piece 54B is moved back towards the 
rocker, using the actuator, so that the clamping piece comes to rest 
against the stop surface 56. Once the rocker has been pivoted into the 
resting position, the clamping piece is tightened fast against the stop 
surface 56 using the actuator, thus fixing the rocker arrangement in the 
resting position. 
As the pivoting axis 59 of the lever arm 54 is positioned with some spacing 
below the rocker axis 44, the lever arm 54 is always held in a defined 
position and thus cannot accidentally pivot out of the respective pivoting 
position if, for example, vibration causes the clamping element to release 
unintentionally (FIG. 7). The lever arm can also serve as a remote control 
for pivoting the rocker when the clamping element is released. 
______________________________________ 
Reference numbers 
______________________________________ 
10 servo-pendulum rudder 
11 servo-pendulum rudder shaft 
12 axis of rotation 
13 servo-pendulum rudder blade 
14 pendulum arm 
15 pendulum axle 
16 bearing region 
17 cantilever bolt 
19 pendulum arm holder 
20 auxiliary rudder 
21 supporting structure 
22 mounting element 
23 auxiliary rudder shaft 
23A head 
24 axis of rotation 
25 rotatory force transmission component 
26 hump 
30 positioning device (transducer) 
31 windvane 
32 connecting rod 
33 housing 
40 drive connection 
41 drive member 
42 toothed bevel gear 
43 driven member 
43A rocker leg 
43B rocker leg 
44 rocker axis 
45 toothed bevel gear 
46A stop surface 
46B stop surface 
47 auxiliary steering tiller 
48 blocking element 
49 blocking counter 
51 recesses 
52 bores 
53 swivel bolts 
54 lever arm 
54A lateral axis 
54B clamping piece 
54C screw clamp sleeve 
55 elongated hole 
56 stop surfaces 
57 stop surfaces 
58 actuator 
59 pivoting axis 
100 self-steering system 
A view 
B view 
C view 
D view 
K keel line 
B boat 
w windvane pivot 
R rotatory movement 
S stern 
H auxiliary rudder movement 
P pendulum movement 
SK desired course setting 
______________________________________