Patent Application
20110009017
1. Field of the Invention
The present invention relates to a steering system for a marine vessel and, in particular, to a steering system for a marine vessel which has a primary propulsion unit and an auxiliary propulsion unit.
2. Description of the Related Art
Marine vessels are often provided with a primary propulsion unit and an auxiliary propulsion unit. Typically a tie bar couples the primary propulsion unit and the auxiliary propulsion unit. U.S. Pat. No. 6,406,340 to Fetchko et al. and U.S. Pat. No. 7,128,626 to Dudra et al., the full disclosures of which are incorporated herein by reference, both disclose using a tie bar to couple a primary propulsion unit and an auxiliary propulsion unit. This allows the propulsion units to be steered simultaneously.
It is also known to use a cable to couple a primary propulsion unit and an auxiliary propulsion unit. U.S. Pat. No. 4,836,812 to Griffiths, the full disclosure of which is also incorporated herein by reference, discloses using a cable to couple a hydraulic cylinder of a primary propulsion unit to a steering arm of an auxiliary propulsion unit. Coupling the propulsion units with a cable provides the advantage of a flexible and rotatable connecting member. However, connecting the cable to the hydraulic cylinder of the primary propulsion engine may limit rotation of the cable and/or unduly twist the cable when primary propulsion unit is tilted. This may result in jamming and less motion being transmitted to the auxiliary propulsion unit.
There is accordingly a need for an improved steering system for a marine vessel which has a primary propulsion unit and an auxiliary propulsion unit.
It is an object of the present invention to provide an improved steering system for a marine vessel which has a primary propulsion unit and an auxiliary propulsion unit.
In particular, it is an object of the present invention to provide an improved steering system for a marine vessel in which a cable couples a primary propulsion unit to an auxiliary propulsion unit.
There is according provided a steering system which comprises a steering assembly for steering a primary propulsion unit. The steering assembly includes an actuator for imparting steering movement to a steering member of the primary propulsion unit. A push/pull cable operatively connects the actuator to a steering member of an auxiliary propulsion unit. The push/pull cable extends through a tilt tube of the primary propulsion unit and is capable of transmitting steering movement from the actuator to the steering member of the auxiliary propulsion unit.
There is also provided a method for coupling a primary propulsion unit to an auxiliary propulsion unit. One embodiment of the method comprises:
forming an axial passageway in a support rod which extends through a tilt tube of the primary propulsion unit;
operatively connecting a push/pull cable to a steering assembly of the primary propulsion unit;
extending the push/pull cable through the passageway; and
operatively connecting the push/pull cable to a tiller of the auxiliary propulsion unit.
The steering system disclosed herein provides the advantage of allowing independent tilting of the primary propulsion unit and auxiliary propulsion unit. Furthermore, twisting of the push/pull cable is minimized.
The invention will be more readily understood from the following description of following embodiments thereof given, by way of example only, with reference to the accompanying drawings, in which:
Referring to the drawings and first to
The steering system 10 includes a hydraulic steering assembly 20 which steers the primary propulsion unit 14. The steering assembly 20 includes an actuator in the form of hydraulic cylinder 22 with a piston rod 24 reciprocatingly mounted therein allowing for relative movement of the cylinder 22 along a piston rod axis 100. The cylinder 22 has a pair of spaced-apart cylinder arms 26 and 28 which extend radially outward of the cylinder 22. A pivot plate 30 is pivotably connected to each of the cylinder arms 26 and 28 by means of pivot pins 27 and 29, respectively. The plate 30 extends between the cylinder arms 26 and 28 and can pivot about the pins 27 and 29. A steering member or tiller 32 of the primary propulsion unit 14 is pivotably connected to the plate 30. Support arms 34 and 36 connect respective ends of the piston rod 24 to a support rod 38 of a tilt tube 40 of the primary propulsion unit 14. This is better shown in
Referring back to
The relative linear movement of the cylinder 22 is also transmitted by a connecting member, in the form of a push/pull cable 46, to the auxiliary propulsion unit 16, thereby causing the auxiliary propulsion unit 16 to be steered. The push/pull cable 46 is a conventional push/pull cable similar to types available from Teleflex Canada Inc. of 3831 No. 6 Road, Richmond, British Columbia, Canada V6V 1P6. The push/pull cable 46 is provided cable rods 48 and 50 at opposite ends thereof. As shown in
The push/pull cable 46 extends from the connecting arm 56, through both the tilt tube 40 of the primary propulsion unit 14 and a tilt tube 74 of the auxiliary propulsion unit 16, to the steering arm 68. In one embodiment the tilt tubes 40 and 74 are substantially aligned along a common horizontal axis. The push/pull cable 46 accordingly extends substantially linearly in the horizontal direction. However, the cable is also flexible, allowing it to curve if required, for example, if the tilt tubes 40 and 74 are not aligned. The bend shown in
Referring now to
The push/pull cable 46 also has a cable portion 84. The cable portion 84 extends between the cable rods 48 and 50. As seen in
The push/pull cable 46 further includes an outer sleeve or jacket 86 which extends between the propulsion units 14 and 16 and, at least partially, houses the cable portion 84. As shown in
In operation, an operator steers the first propulsion unit 14 by actuating the helm pump to pump hydraulic fluid to the cylinder 22 of the steering system 20. This causes the cylinder 22 to reciprocate linearly with respect to the marine vessel 12 as described above. This relative linear movement of the cylinder 22 causes the tiller 32 of the primary propulsion unit 14 to pivot, thereby causing the primary propulsion unit 14 to be steered. The relative linear movement of the cylinder 22 is also transmitted to the auxiliary propulsion unit 16, thereby causing the auxiliary propulsion unit 16 to be steered. In particular, the relative linear movement of the cylinder 22 is transmitted through the bracket 58 and connecting arm 56 to the first cable rod 48 of the push/pull cable 46. This causes the first cable rod 48 to move linearly. The linear movement of the first cable rod 48 is transmitted through the cable portion 84 of the push/pull cable 46 to the second cable rod 50. This cause the second cable rod 50 to move linearly. Movement of the second cable rod 50, through the steering arm 68, causes the tiller 70 of the auxiliary propulsion unit 14 to pivot thereby causing the auxiliary propulsion unit to be steered.
Extending the push/pull cable 46 through tilt tubes 40 and 74 and, in particular through the support rods of the tilt tubes, allows for independent tilting of the primary propulsion unit 14 and the auxiliary propulsion unit 16. Furthermore, twisting of the push/pull cable 46 is minimized.
The steering system disclosed herein may be retrofitted to existing marine vessels by boring through the tilt tubes of existing propulsion units or by providing support rods for the tilt tubes with central passageways or bores to receive a push/pull cable. For example, the steering system disclosed herein may be retrofitted to the SEA STAR® steering system offered by Teleflex Canada Inc.
It will further be understood by a person skilled in the art that many of the details provided above are by way of example only, and are not intended to limit the scope of the invention which is to be determined with reference to the following claims.
