Remote control unit

In the construction of a remote control unit advantageously usable for an automatic steering system of small-sized boats and cruisers, a rotatable main-dial, which is adapted for adjusting the resistance of a main variable resistor for manual steering, is always elastically registered at the zero-point for automatic zero-point resetting purpose. In addition to the automatic zero-point resetting function without requirement for any highly skilled technique, unexpected and dangerous accidental turning of the main-dial can be successfully obviated.

BACKGROUND OF THE INVENTION 
The present invention relates to an improved remote control unit, and more 
particularly relates to improvement in the zero-point resetting function 
of a remote control unit advantageously usable for automatic steering 
system of small-sized boats and cruisers. 
In general, a remote control unit is provided with a variable resistor 
whose resistance is freely adjustable by manually turning a dial 
mechanically coupled to the variable resistor. In use, the remote control 
unit is operationally coupled to a rudder mechanism via a main control 
unit. Change in the resistance of the above-described variable resistor 
causes corresponding change in the electric signal, e.g. voltage signal, 
to be passed to the main control unit from the remote control unit in 
order to activate the rudder mechanism. 
The conventional remote control unit of the above-described type is a 
simple combination of a manually operable dial with a potentiometer and is 
provided with the no automatic zero-point resetting function. Therefore, 
when the dial is turned over a prescribed angle and, as a result, the boat 
starts to change the sailing course to the selected one, the dial needs to 
be gradually and carefully returned to the zero-point in accordance with 
development of the change in the sailing course. This manual resetting 
operation required highly skilled technique based upon long experience in 
practice. In addition, such gradual zero-point resetting adjustment is 
quite troublesome and inconvenient for the operator who is busy with 
various work necessary for safe navigation of the boat. Further, when any 
shock is applied to the remote control unit and the dial is made to turn 
unexpectedly, the rudder is turned over an angle corresponding to the 
unexpected turning angle of the dial and kept at the turned angular 
position until the operator finds the unexpected turning of the dial and 
resets the dial to the zero-point. This naturally causes corresponding 
unexpected change in the sailing course of the boat which is seriously 
dangerous when the boat sails, for example, through a narrow strait. 
SUMMARY OF THE INVENTION 
It is an object of the present invention to provide a compact and light 
remote control unit easily operable by simple finger action. 
It is another object of the present invention to provide a remote control 
unit which can be reset to the zero-point by simply detaching the user's 
finger from the dial for adjusting the variable resistor without requiring 
any highly skilled technique. 
It is the other object of the present invention to provide a remote control 
unit in which the dial for adjusting the variable resistor never rotates 
accidentally even when a shock is accidentally applied to the unit. 
It is a further object of the present invention to provide a remote control 
unit advantageously usable for the automatic steering system of a 
small-sized boat or cruiser which has an enhanced operational reliability 
in quickly responding to the sailing mode of the boat. 
In accordance with the basic aspect of the present invention, an A-M switch 
for shifting the steering mode from automatic to manual and vice versa is 
contained within a cylindrical main casing, a main-dial operationally 
coupled within the main casing to a main variable resistor for manual 
steering is axially turnably mounted to one end of the main casing, the 
main-dial is always elastically registered at the zero-point while being 
allowed to turn over prescribed angular ambit on both sides of the 
zero-point and a sub-dial operationally coupled within the main casing to 
a subordinate variable trimming resistor is axially rotatably mounted to 
the other end of the main casing. 
Although the following description is focussed upon application of the 
present invention to the automatic steering system of small-sized boats 
and cruisers, a wide variety of applications is employable with minor 
modifications popular to the skilled in the art.

DESCRIPTION OF THE PREFERRED EMBODIMENT 
The construction of one example of an automatic steering system in which 
the remote control unit of the present invention may be used is roughly 
illustrated in FIG. 1. As shown therein, the automatic steering system 
comprises a sensor circuit 1, a main control unit 2 which receives signals 
from the sensor circuit 1, a rudder mechanism 3 operationally coupled to 
the main control unit 2 and a remote control unit 4 coupled to the main 
control unit 2 via suitable wires 41. 
The sensor circuit 1 senses variations in factors which influence the 
navigation of the boat such as navigation course, wind heading and 
tideway, and inputs deviation signals representative of these variations 
to the main control unit 2. 
The remote control unit 4, which is used as a remote steering unit in the 
present application, includes an A-M switch 42 for shifting the steering 
mode from automatic to manual and vice versa. The remote control unit 4 
further includes a main variable resistor 43 for manual steering and a 
subordinate variable resistor 44 for trimming which are coupled in series 
to each other. 
The resistance of the main variable resistor 43 is adjusted by manually 
turning a main-dial (not shown in FIG. 1 but described below) provided on 
the remote control unit 4. In accordance with the change in the resistance 
of the main variable resistor 43, the electric signal, e.g. a voltage 
signal, to be passed to the main control unit 2 from the remote control 
unit 4 changes in order to drive the rudder mechanism 3, accordingly with 
the result that the rudder is turned and sailing course of the boat is 
changed. 
The resistance of the subordinate variable resistor 44 is adjusted by 
manually turning a sub-dial (not shown in FIG. 1 but described below) 
provided on the remote control unit 4. Subordinate variable resistor 44 is 
provided for fine compensation of the main variable resistor 43. As 
described above, remote steering is effected by manually turning the 
maindial to either side of a predetermined zero-point. When the main-dial 
is registered at the zero-point, the rudder is placed on the neutral axis. 
In practice, however, the sailing course of the boat is greatly influenced 
by tideway and wind and the boat does not sail straight on the selected 
course even when the main-dial is registered at the zero-point and the 
rudder is on the neutral axis. In addition, every rudder mechanism 3 has 
its own operational habit and, due to this operational habit, the boat 
does not always sail straight on the selected course even when the rudder 
is registered at the neutral axis. 
For these reasons, the boat does not always sail straight on the selected 
course even when the main dial is registered at the zero-point. In order 
to obviate this problem, the subordinate variable resistor 44 is coupled 
in series to the main variable resistor 43 and resistance of the 
subordinate variable resistor 44 is adjusted by turning the subdial so 
that the boat sails straight on the selected course when the main-dial is 
registered at the zero-point. 
One embodiment of the remote control unit in accordance with the present 
invention is shown in FIGS. 2, 3A and 3B. The remote control unit 4 
includes a cylindrical main casing 51 closed at one end by an end cap 52 
through which a locally threaded shaft 53 extends in an axially rotatable 
arrangement. Outside the main casing 51, a main-dial 54 is secured to 
shaft 53 via a fastening screw 58 in a coaxial fashion. Inside the main 
casing 51, the shaft 53 carries the movable parts such as the slide-arm of 
the above-described main variable resistor 43 (see FIG. 1). The slide 
brush rotates with the arm shaft 53. A wing shaped knob 56 projects from 
main-dial 54 and extends over the periphery of the main casing 51. A pin 
57 projects from the casing of the main variable resistor 43 and is 
received in a hole 60 formed in the inner face of the end cap 52. By 
operation of a fastening nut 65 screwed over the shaft 53 on the outer 
face of the end cap 52 the casing of, the main variable resistor 43 is 
pulled towards the end cap 52 and pin 57 is strongly pressed against the 
end cap 52 in order to interlock the casing of the main variable resistor 
43 against turning with respect to the main casing 51. 
As already described, provision of an elastic mechanism for effecting 
auto-resetting of the main-dial 54 to the zero-point is the gist of the 
present invention. 
As shown in FIGS. 2 and 3A, a movable driver disc 59 is coaxially secured 
to the inner face of the main-dial 54 and has a pair of hooks 59a 
projecting towards the end cap 52 at symmetric positions on the periphery 
of the driver disc 59. In combination with this, a stationary stopper disc 
62 is coaxially secured to the outer face of the end cap 52 via an 
intervening seal plate 61 and has a pair of hooks 62a projecting towards 
the main-dial 54 at symmetric positions on the periphery of the stopper 
disc 62. Both discs 59 and 62 are arranged so that, when the main-dial 54 
is registered at the zero-point as shown in FIG. 3A, the hooks 62a of the 
stopper disc 62 are located on outer sides of the hooks 59a of the driver 
disc 59. The seal plate 61 and the stopper disc 62 are both provided with 
center apertures for allowing free turning of the shaft 53. An overriding 
spring 63 is provided at a position between the driver disc 59 and the 
stopper disc 62 with its center helical portion loosely winding around the 
shaft 53 and ends of its branches being in abutting engagement with the 
hooks 59a and 62a as shown in FIG. 3A. 
When the knob 56 is turned manually, the main-dial 54, the shaft 53, the 
drive disc 59 and the slide-arm of main variable resistor 43 turn about 
the axis of the shaft 53 in a common direction over a common turning 
angle. 
Assuming that the knob 56, i.e. the shaft 53, is turned clockwisely from 
the angular position shown in FIG. 3A, the left side hook 59a of the 
driver disc 59 pushes the left side branch of the override spring 63 
clockwise and the left side hook 59a is disengaged from the left side hook 
62a of the stopper disc 62. The right side branch of the override spring 
63 is interlocked against movement by engagement with the right side hook 
62a of the stopper disc 62. Thus, the override spring 63 is forced to 
undergo elastic deformation. Concurrently with this process, turning of 
the shaft 53 causes corresponding turning of the slide arm of the main 
variable resistor 43 and the latter deviates from the zero-point in order 
to change its resistance. This change in the resistance of the main 
variable resistor 43 causes corresponding change in the electric signal, 
e.g. voltage signal, to be passed to the main control unit 2 from the 
remote control unit 4 and the rudder mechanism 3 is driven for operation, 
thereby the navigation course of the boat being accordingly changed. 
As the force applied to the knob 56 is withdrawn, the tension in the 
above-described override spring 63 makes the left side branch return 
counterclockwise and, accordingly, push the left side hook 59a in a 
direction which causes driver disc 59 to turn counterclockwise about the 
axis of the shaft 53. This rotation of the driver disc 59 naturally 
accompanies similar and common turning of the main-dial 54, the knob 56, 
the shaft 53 and the slide brush of the main variable resistor 43. The 
returning movement of the left side branch of the override spring 63 is 
stopped upon abutment against the left side hook 62a of the stopper disc 
62. Thus, the override spring 63 resumes the original nondeformed 
disposition with both branches resuming the initial angular positions. 
Accordingly, the main-dial 54, the knob 56 and the shaft 53 also resume 
the initial angular position and the main variable resistor 43 is again 
registered at the zero-point. 
It will be well understood that substantially similar process is traced by 
the above-described mechanical parts when the knob 56, i.e. the shaft 53, 
is turned counterclockwisely from the angular position shown in FIG. 3A. 
The end of the main casing 51 opposite to the main variable resistor 
mounting is closed by an end cap 64 which has a center aperture for 
allowing idle passage of a locally threaded shaft 66 for the subordinate 
variable resistor 44. A pin 69 projects from the casing of variable 
resistor 44 and is received in a hole 71 formed in the inner face of the 
end cap 64. By operation of a fastening nut 70 screwed over the shaft 66 
on the outer face of the end cap 64, variable resistor 44 is pulled 
towards the end cap 64 and pin 69 is strongly pressed against the end cap 
64 in order to interlock the casing of the subordinate variable resistor 
44 against turning with respect to the main casing 51. Outside the end cap 
64, the shaft 66 coaxially and securedly carries the sub-dial 67 which is 
partly inserted into the main casing via an O-ring 68. 
By turning sub-dial 67, the slide brush of subordinate variable resistor 44 
is displaced via the shaft 66 so that the resistance of variable resistor 
44 is adjusted as desired. This contributes to the hereinbefore explained 
compensation of the main variable resistor 43. 
The A-M switch 42 is provided on the periphery of the main casing 51. 
Although a push button type switch is used for this purpose in the 
illustrated embodiment, different types of switches such as a snap type 
switch is employable also. The A-M switch 42 is advantageously provided 
with an water-tight construction. 
In accordance with the present invention, the remote control unit is of a 
very light construction and easily operable by simple finger action 
without requiring any highly skilled technique for effecting zero-point 
resetting. Since the main-dial is always urged by the elastic mechanism 
into keeping the zero-point, accidental shock applied to the remote 
control does never accompany unexpected turning of the main-dial which, 
under some situations, may cause serious accidents. Especially when the 
present invention is applied to the automatic steering system of a boat or 
the like, it assures high safety in navigation and optimum navigation mode 
under variable environmental conditions. In addition, it frees the busy 
operator on the boat or crusers from the troublesome zero-point resetting 
work which otherwise requires highly skilled technique.