Patent Application
20050287884
This invention relates to marine steering systems and, in particular, to marine hydraulic steering systems for steering outboard motors which can tilt relative to the stern of a marine craft.
Marine steering systems have been developed for hydraulically steering outboard motors, but which permit tilting upwards of the outboard motors when the motors are not in use. Such steering systems conventionally included a steering wheel with an associated hydraulic pump and hydraulic lines connecting the pump to a steering assembly adjacent to the outboard motor. Such a system is disclosed, for example, in U.S. Pat. No. 5,997,370 to Fetchko et al. and in earlier U.S. Pat. No. 5,092,801 to McBeth. A system for steering twin outboard motors is disclosed in U.S. Pat. No. 6,406,340 to Fetchko et al.
Typically the systems include a pivot plate or pivot member which is pivotally connected to the tiller of an outboard motor. A pair of support arms or support brackets extend outwardly from the tilt tube of the motor. The piston rod of a hydraulic actuator is mounted on the support arms. The actuator has actuator arms extending outwardly from the cylinder thereof which are pivotally connected to the pivot member for pivoting about an axis parallel to the piston rod. The pivotal connection typically includes cylindrical passageways in the actuator arms and the pivot plate and separate pins extending through the cylindrical passageways which are retained by bolts.
In these earlier systems the actuator arms are typically formed in one piece with the barrel of the hydraulic cylinder. The cylinder has separate end glands connected to the barrel which slidably and sealingly receive the piston rod so that the piston rod reciprocates through the end glands.
This arrangement requires separate bolts or pins for connecting the hydraulic actuator to the pivot plate. Typically this requires two bolts, two washers and two pins. The pins are usually made of a high-strength material with high wear resistance in order to withstand the loads encountered.
According to one aspect of the invention, there is provided a hydraulic steering assembly for applying a force to a tiller of a marine, outboard propulsion unit and for rotating said propulsion unit about a steering axis between a center position and hard over positions to each side of the center position. The propulsion unit is supported for arcuate movement about a tilt axis which is generally perpendicular to the steering axis. The steering assembly comprises a hydraulic steering actuator including a cylinder and an elongated piston rod reciprocatingly mounted within the cylinder and extending through the cylinder for movement along a piston rod axis. The piston rod has opposite ends. A pair of support arms is pivotable about the tilt axis of said propulsion unit and is connected to the piston rod near the opposite ends thereof, the support arms allowing arcuate movement of the rod about the tilt axis, maintaining the rod axis parallel to the tilt axis. A pivot member is pivotally mountable on the tiller of said propulsion unit for pivoting about a link axis which is parallel to the steering axis. There is a pair of actuator arms, each arm being connected to the cylinder and extending radially outwards with respect to the piston rod axis, each of the actuator arms having an integral cylindrical projection aligned with the second link axis and rotatably received within a complementary cylindrical recess of the member, thereby pivotally connecting the actuator arms to the member.
Preferably the cylinder includes a barrel with opposite ends and an end fitting connected to the barrel at each end thereof. The piston rod extends slidably through the end fittings, the actuator arms being integral with the end fittings.
According to another aspect of the invention, there is provided a hydraulic steering assembly for applying a force to a tiller of a marine, outboard propulsion unit and for rotating said propulsion unit about a steering axis between a center position and hard over positions to each side of the center position. The propulsion unit is supported for arcuate movement about a tilt axis which is generally perpendicular to the steering axis. The steering assembly comprises a hydraulic steering actuator including a cylinder and an elongated piston rod reciprocatingly mounted within the cylinder and extending through the cylinder for movement along a piston rod axis. The piston rod has opposite ends. A pair of support arms is pivotable about the tilt axis of the propulsion unit and is connected to the piston rod, allowing arcuate movement of the rod about the tilt axis, maintaining the rod axis parallel to the tilt axis. A member is pivotally mounted on the tiller of the propulsion unit for pivoting about a link axis which is parallel to the steering axis. There is a pair of actuator arms, each actuator arm being connected to the cylinder and extending radially outwards with respect to the piston rod axis. Each of the actuator arms has a cylindrical recess aligned with the second link axis. The member has a pair of integral cylindrical projections rotatably received within the recesses, thereby pivotally connecting the actuator arms to the member.
According to a further aspect of the invention, there is provided an end member for a hydraulic actuator for a marine hydraulic steering system. The actuator has a cylindrical barrel and a longitudinal actuator axis. The end member has a fitting for connecting the end member to one end of the barrel, and an arm configured to extend radially outwards from the actuator axis when the member is connected to the one end of the barrel. A cylindrical projection extends from the arm so as to be parallel to the actuator axis, whereby the hydraulic actuator can be pivotally mounted by inserting the cylindrical projection rotatably in a complementary recess of another component of the steering system.
According to a still further aspect of the invention, there is provided a hydraulic steering assembly for applying a force to a tiller of a marine, outboard propulsion unit and for rotating said propulsion unit about a steering axis between a center position and hard over positions to each side of the center position, the propulsion unit being supported for arcuate movement about a tilt axis which is generally perpendicular to the steering axis. The steering assembly comprises a hydraulic steering actuator including a cylinder and an elongated piston rod reciprocatingly mounted within the cylinder and extending through the cylinder for movement along a piston rod axis. The piston rod has opposite ends. A pair of support arms is pivotable about the tilt axis of said propulsion unit and is connected to the piston rod near the opposite ends thereof. The support arms allow arcuate movement of the rod about the tilt axis, maintaining the rod axis parallel to the tilt axis. A pivot member is pivotally mounted on the tiller of said propulsion unit for pivoting about a link axis which is parallel to the steering axis. There is a pair of actuator arms, each said actuator arm being connected to the cylinder and extending radially outwards with respect to the piston rod axis. There is a pivotal connection between each said actuator arm and said pivot member including a cylindrical projection integral with one of said each arm and said pivot member and a complementary cylindrical recess on another of said each arm and said pivot member rotatably receiving the cylindrical projection. The pivotal connection permits relative pivoting between the actuator arms and the pivot member about a second link axis
According to a still further aspect of the invention, there is provided a pivot member for a hydraulic steering assembly having a linear steering actuator for applying a force to a tiller of a marine, outboard propulsion unit and for rotating said propulsion unit about a steering axis between a center position and hard over positions to each side of the center position. The pivot member includes means for pivotally mounting the pivot member on the tiller of said propulsion unit for pivoting about a link axis which is parallel to the steering axis. The pivot member has integral spaced-apart cylindrical projections rotatably receivable in complementary cylindrical recesses of the actuator, whereby the actuator is pivotally mounted on the pivot member.
The invention offers notable advantages compared to the prior art. It does away with a significant number of parts compared to a typical prior art unit, including two bolts, two washers and two pins and consequently reduces costs and assembly time.
The invention also allows the pivot plate or other pivot member to be removed much more easily. This is beneficial because some applications require the pivot plate to be mounted upside down or even require an alternative plate, thus making the easy removal of the pivot plate very convenient for the end users.
Also the previous designs are more difficult to disassemble and reassemble compared to the invention, making a mistake less likely with the invention. Designs according to the invention are preferred because they are simpler and safer.
In a typical prior art unit the actuator arms are formed as part of the barrel of the hydraulic cylinder. Integrating the pins with such arms would be difficult or impossible to machine and difficult to assemble. Accordingly, in one preferred embodiment of the invention, the pivot pins are replaced by cylindrical projections integral with end fittings of the cylinder which include the end glands. This makes the concept feasible by permitting relatively easy machining of the cylindrical projections and easy assembly of the apparatus.
In the drawings:
Referring to the drawings, and first to
Midsection 34 of the motor has a tilt tube 36 with support rod 37, shown in
A pair of support arms 40 and 42 are mounted on opposite ends of the support rod. Each arm has an aperture 48, shown for arm 40, which connects each arm to one end of a piston rod 50 of hydraulic actuator 25. The piston rod is reciprocatingly mounted within the cylinder 26, and extends through end fittings 59 and 61 of the cylinder, for relative movement along a piston rod axis 54 (also referred to herein as an “actuator axis”). In fact the rod 50 is axially stationary with respect to the boat, while the cylinder 26 reciprocates. The support arms allow arcuate movement of the piston rod 50 and the actuator 25 about the tilt axis 38, while maintaining the rod axis 54 parallel to the tilt axis 38.
There is a member, in this case a pivot plate 76, which is pivotally connected to tiller arm 80 of the motor 32, by a tiller joint formed by bolt 82 as well as washer 83, nut 87 and a bushing extending through the aperture in the pivot plate (not shown) to permit pivoting about a first link axis 77 which is parallel to the steering axis 90.
End member or end fitting 59 is shown in better detail in
As may be seen best in
A variation of the invention is shown in
The end members are generally similar to the end members of the previous embodiment, but have a cylindrical recess 160 in place of the cylindrical projection 102. The construction is generally the opposite, compared with the previous embodiment, insofar as the pivotal connection between the member 76.1 and the end members of the actuator are concerned. In other words, the cylindrical projections are on the member 76.1 instead of on the end members of the actuator. However the cylindrical members 157 of the member 76.1 comprise a single piece with the rest of the member. The member in this embodiment is formed by a forged stainless steel bar with members 157 machined and washer 158 being installed over the member. Alternatively it could be an aluminum plate with the members 157 machined.
It will be understood by someone skilled in the art that many of the details provided above are given by way of example only and can be altered or deleted without departing from the scope of the invention as set out in the following claims.
