GB2353262A

GB2353262A - Vessel autopilot system

Info

Publication number: GB2353262A
Application number: GB0019098A
Authority: GB
Inventors: Garnett Brad
Original assignee: Raytheon Marine Ltd
Current assignee: Raymarine 2002 Ltd
Priority date: 1999-08-17
Filing date: 2000-08-03
Publication date: 2001-02-21
Anticipated expiration: 2020-08-03
Also published as: GB9919478D0; GB0019098D0; GB2353262B

Abstract

A vessel steering system comprises steering means 5 connected through a powered ram 10 to a tiller arm 11 for steering the vessel and an autopilot having a drive unit 1 connected in parallel to the steering means for driving the tiller arm under the control of a control unit of the autopilot. The drive unit of the autopilot is connected to the tiller arm by a flexible push-pull cable 3 the outer sleeve 4 of which is connected to the powered ram while the inner rod 9 of said cable is connected to the tiller arm. The outer sleeve of the cable may be connected to the control valve 8 of the ram which may be hydraulic by means of a coupling bracket 7. The steering system may be provided as a kit for retro-fitting to preexisting steering mechanisms.

Description

2353262 AUTOPILOT SYSTEM The present invention is concerned with autopilot

systems anc in particular relates to autopilot systems which can be used to move the tiller of a marine vessel.

It is now becoming more common for boats to have an autopilot system which permits automated steering of the vessel in order that a preset heading (orientation) may be maintained. The preset heading is compared with the heading of the boat as determined by a heading sensor (which outputs a signal called the compass heading).

Sometimes, autopilot drive units are fitted to an hydraulic power assist ram which forms part of the steering mechanism of the vessel. The autopilot operates by moving a control.valve which is an integral part of the hydraulic power assist ram., Movement of the valve to either side of a central position allows hydraulic fluid under pressure to extend or retract an hydraulic cylinder. Extension or retraction of the hydraulic ram results in movement of the vessels tiller, the movement of which is transmitted-to movement of the rudder of the vessel.

Autopilot systems such as these are well known, and can be fitted to engines in which there is a sufficient amount of space in.which to position the autopilot drive unit which may be relatively bulky. However, in vessels with restricted engine space, the fitting of autopilots 2 can be difficult, often requiring an autopilot to be custom-built to fit in the available space in a particular engine. In some vessels, particularly small. vessels, conventional autopilot systems may not be able 5 to be fitted at all.

Even if an autopilot system is fitted to the power assist ram mechanism in a restricted engine space, there will arise the danger of damage to the existing engine components by incorrect fitting of the autopilot drive unit. There is also a danger of damage to the autopilot device itself caused by inappropriate positioning of vulnerable plastic components of the autopilot device close to hot engine parts (such as' turbo charger casings etc).

According to the present invention there is provided a steering system. connected through a powered ram to a tiller arm for driving under control of the steering, and an autopilot having a drive unit connected in parallel to this steering system for driving the tiller arm under control of the control unit of the autopilot. In the invention, 'the autopilot drive unit is connected to the tiller arm via a flexible push-pull cable with the sleeve of that cable being connected to the powered ram and the inner rod of the cable being fixed to the tiller arm.

Preferably the powered ram is a hydraulic ram, and the sleeve of the cable is then fixed to the control 3 valve of the hydraulic ram.

As the autopilot unit uses a flexible pushpull cable, it can be positioned at almost any position within the vessel in which there is sufficient space. This enables easy fitting of the autopilot to a pre-existing steering mechanism.

Therefore, it is envisaged that as well as being provided as part of a complete steering system, the autopilot components may be provided in the form of a kit for retro-fitting of an autopilot to a pre-existing steering mechanism.

In order that movement of the components of the drive unit of the autopilot is transmitted to cause. movement of the tiller arm, the outer sleeve must be attached to the. powered ram, and preferably to the control valve of the powered ram, at an easily accessible position and preferably without the need for modification of the steering control valve. Ideally, it should be affixed to a pre-existing part of the drive unit.

- Although conventional steering drive units vary widely in both shape and size, they generally share the feature that connection of the steering cable to the powered ram of the drive unit. is effected via a cable coupling nut. Such nuts are generally easily accessible and so, in the present invention, the outer sleeve of the push-pull cable is fixed to the cable coupling nut of the 4 cable steering system via a coupling bracket. Such a coupling bracket may have two clamping portions, the first of which is adapted to fit an hexagonal -shaped cable coupling nut and the second of which is adapted to clamp the outer sleeve of the push-pull cable.

As the cable coupling nuts of different steering drive units are generally uniform in shape and size, such coupling brackets may be used to affix the push-pull cable of an autopilot drive unit to almost any pre- existing cable/hydraulic steering drive system. Such coupling brackets may therefore be used as part of an autopilot kit for retro-fitting to pre-existing steering mechanisms.

As the bulky autopilot drive unit.may be positioned remotely from the steering mechanisms either inside or outside of the engine compartment, the autopilot may be installed in an engine with very limited available space and without modification of the existing engine or of the autopilot drive unit to allow the autopilot to fit.

Furthermore, this arrangement ensures that the forces generated by the autopilot drive unit are transmitted through the push-pull cable and not through brackets and screws used to attach the autopilot drive unit. This arrangement protects against damage to components due to positioning of the autopilot drive unit in too close proximity to other engine components.

An embodiment of the present invention will now be described, by way of example, with reference to the accompanyir.g drawings in which:

Fig. 1 is a perspective view of a steering apparatus 5 and autopilot incorporating the invention.

Fig. 2 is a perspective view of another steeringapparatus incorporating the present invention, showing, in greater detail the attachments of the autopilot drive unit to the steering apparatus.

Fig. 1 shows a perspective view of an autopilot drive unit 1 attached to a hydraulic steering apparatus 3, the control valve 8 and hydraulic power-assist ram 10 being parts of the hydraulic steering system. A steering cable 5 (a portion of which is shown) is attached with a cable coupling nut 6 to a control valve 8. Movement of the steering cable is transmitted to the tiller aided by the hydraulic power-assist ram 10.

The autopilot comprises a drive unit 1, having a motor, a gearbox and a lead screw, a housing 2 and a pushpull cable 3. The push-pull cable 3 comprises an outer sleeve 4 and an inner rod 9. The outer sleeve.4 is connected at one end to an aluminium housing 2. The other end of the outer sleeve 4 of the push-pull cable 3 is attached to the control valve 8 via an "'hexagonal'' bracket 7, which clamps the outer sleeve 4 to the coupling nut 6. One end of the inner rod 9 of the push- 6 pull cable 3 is attached to the motor/gearbox/lead screw of the drive unit 1. The other end of the inner rod 9 is attached via a pivoting rod attachment 12 to the tiller pin 13 of the tiller 11.

Movement of the rudder of a vessel operating in the absence and presence of control by an autopilot drive unit of the invention will now be described with reference to Fig. 2. Fig. 2 shows a partial view of a steering mechanism 3 to which is attached push-pull cable 3. As in Fig. 1, the outer sleeve 4 of the cable 3 is attached to the cable coupling nut 6 via an hexagonal bracket 7 with the inner rod 9 connected to the tiller pin 13 via a pivotable rod attachment 12.

During normal steering in the absence of control by the autopilot, the movement of the rudder of the marine ves. sel is effected via the steering cable 5. Movement of a steering means such as a steering wheel is transmitted through the steering cable 5 to a control valve 8. The steering cable 5 is attached to the control valve 8 via the coupling nut 6. Movement of the steering cable 5 is transmitted to the control valve 8 which allows hydraulic fluid under pressure to extend or retract an hydraulic ram 10. Movement of the ram 10 is transmitted to the tiller 11.

The autopilot can be used to permit automated steering of the vessel's rudder. During autopilot 7 controlled steering, an autopilot processing unit controls the movement of the components of the autopilot drive unit,,. which moves the control valve 8, extending or retracting the hydraulic power assisted ram 10, movement of which is transmitted to the tiller 11. As bracket 7 securely fixes the outer sleeve 4 of the push-pull cable 3 to the control valve 8, movement of the inner rod 9 reacts against the fixed tiller pin 13, causing movement of the control valve 8 relative to the tiller pin 13.

Movement of the control valve 8 allows hydraulic fluid under pressure to extend or retract the hydraulic ram 10, with movement of the ram 10 transmitted to the tiller 11.

As can be seen from the figures, fixing of the autopilot to a vessel steering mechanism is easily achieved by attachment to existing components of the steering mechanism (cable coupling nut 6 and tiller pin 13). Furthermore, as the drive unit 1 may be positioned remotely from the steering mechanisms, the installation of the autopilot of the invention is simple even in vessels where the engine space is much restricted.

Claims

8 CLAIMS

1. A vessel drive system comprising a steering system connected through a powered ram to a tiller arm for driving a vessel under control of the steering, and an autopilot having a drive unit connected in parallel to the steering system for driving the tiller arm under the control of the control unit of the autopilot, the drive unit of the autopilot being connected to the tiller arm by a flexible push-pull cable, the outer sleeve of that cable being connected to the powered ram, and the inner rod of the cable being connected to the tiller arm.

2. A vessel drive system according to claim 1 wherein the outer sleeve is connected to the control valve of the powered ram.

3. A vessel drive system according to claim 1 or claiin 2 wherein the outer sleeve is connected to the powered ram via a coupling bracket.

4. A vessel drive system according to claim 3 wherein the coupling bracket has first and second clamping portions, the first clamping portion being adapted to receive a coupling nut, the second clamping portion being adapted to receive the outer sleeve of the push-pull cable.

9

5. A vessel drive system according to claim 4 wherein the coupling nut is hexagonal.

6. A vessel drive system according to any one of the preceding claims wherein the powered ram is a hydraulic ram.

7. A kit for forming a vessel drive system according to any one of the preceding claims, the kit including a steering system connectable through a powered ram to a tiller arm, and an autopilot having a drive unit connectable in parallel to the steering system, and a flexible push-pull cable for connecting the drive unit of the autopilot to the tiller arm.

8. A kit for forming a vessel drive system according to any one of the preceding claims including an autopilot having a drive unit connectable through a powered ram to a tiller arm of a steering system of a vessel, and a flexible push-pull cable for connecting the drive unit of the autopilot to the tiller arm.

9. A vessel steering drive system substantially as herein 7 described with reference to and as illustrated in Figs. 1 and 2 of the accompanying drawings.

9. A vessel drive system substantially as herein described with reference to and as illustrated in Figs. 1 and 2 of the accompanying drawings.

i,g Amenchnents to the claims have been filed as follows 1. A vessel steering drive system comprising a steering system connected through a powered ram to a tiller arm for steering the vessel under control of the drive steering system, and an autopilot having a control unit and a drive unit connected in parallel to the steering system for driving the tiller arm under the control of the control unit of the autopilot, the drive unit of the autopilot being connected to the tiller arm by a flexible push-pull cable, the outer sleeve of that cable being connected to the powered ram, and the inner rod of the cable being connected to the tiller arm.

2. A vessel steering drive system according to claim 1 wherein the outer sleeve is connected to the control valve of the powered ram.

3. A vessel steering drive system according to claim 1 or claim 2 wherein the outer sleeve is connected to the powered ram via a coupling bracket.

4. A vessel steering drive system according to claim 3 wherein the coupling bracket has first and second clamping portions, the first clamping portion being adapted to receive a coupling nut, the second clamping portion being adapted to receive the outer sleeve of the push-pull cable.

5. A vessel steering drive system according to claim 4 wherein the coupling nut is hexagonal.

6. A vessel steering drive system according to any one of the preceding claims wherein the powered ram is a hydraulic ram.

7. A kit for forming a vessel steering drive system according to any one of the preceding claims, the kit including a steering system connectable through a powered ram to a tiller arm, and an autopilot having a drive unit connectable in parallel to the steering system, and a flexible push-pull cable for connecting the drive unit of the autopilot to the tiller arm.

8. A kit for forming a vessel steering drive system according to any one of the preceding claims including an autopilot having a drive unit connectable through a powered ram to a tiller arm of a steering system of a vessel, and a flexible pushpull cable for connecting the drive unit of the autopilot to the tiller arm.