Power tilt apparatus for monting an outboard engine on a boat

Abstract: A power tilt apparatus for mounting an outboard engine (1) on a boat comprises a clamp bracket (10) affixed to the boat, a swivel bracket (9) that supports the outboard engine (1), and an electric motor (14) that drives an oil pump (16) to extend and retract a hydraulic cylinder (13) whereby the extension and contraction of said hydraulic cylinder (13) is linked to ends of the swivel bracket (9) and clamp bracket (10) to enable the tilting of the outboard engine (1) up and down. The electric motor (14) and oil pump (16) are placed near the bottom and to the side of the hydraulic cylinder (13) to allow the width of the brackets (9,10) to be narrowed to only accommodate the width of the hydraulic cylinder (13) and to prevent interference between the cylinder (13) and the electric motor (14) or oil pump (16). In order to allow the outboard engine (3) to be manually tilted up or down a manual valve (30) is located in the hydraulic circuit connecting the oil pump (16) to the hydraulic cylinder (13) to return oil to the oil reservoir tank (15) in the event of a breakdown by the electric motor (14). The manual valve (30) is positioned in the oil conduit that connects to the lower oil chamber of the hydraulic cylinder (13), and the manual valve structure is opened and closed by pressing a push button.

Description: The present invention relates to a power tilt apparatus for mounting an outboard engine on a boat according to the preamble of independent claim 1. Power tilt apparatus of these types are preferably installed on small outboard engines. So-called power tilt apparatus have been used in outboard engines mounted on small boats to tilt the engine up out of the water or down into the water using mechanical force, e.g. provided by a motor, instead of manual force. Such apparatus are composed of a hydraulic cylinder, which is operated by an electric motor and an oil pump, and which is axially attached to span the clamp bracket affixed to the stern wall of the boat and the swivel bracket that allows turning the outboard engine in the horizontal direction, wherein the expansion and retraction of said hydraulic cylinder causes the top ends of the swivel bracket and clamp bracket to rotate with respect to each other around a horizontally disposed tilt shaft, in order to raise and lower the outboard engine with respect to the boat. In some power tilt apparatus for outboard engines, the drive means, such as the electric motor, and the oil pump are positioned at some distance from the hydraulic cylinder, and the pump is connected by a long line, but in most such power tilt apparatus, the constituent parts are not separated from each other, the drive means for the hydraulic cylinder, including the electric motor and oil pump being attached integrally. However, with regard to such power tilt apparatus used in the prior art which integrally attaches the drive motor, etc. in a single a unit, as shown in Figure 8, the electric motor 14 connected in series with the oil pump 16 and the reservoir 15 (or the reservoir containing the oil pump) are positioned parallel to the hydraulic cylinder. Overall, this type of power tilt apparatus must be incorporated between the brackets (the swivel bracket 9 and the clamp bracket 10) that affix the outboard engine to the boat. This power tilt apparatus of the prior art requires that these brackets be widened in order to avoid interference with the drive motor and reservoir (oil pump). Further, it is necessary to reinforce the brackets due to the hydraulic cylinder being attached to the brackets in an offset position, which is disadvantageous from a strength perspective. These requirements increase the size and weight of the brackets and increase costs. Further, such an apparatus is difficult to adapt for use on small outboard engines. An example of such a power tilt apparatus for mounting an outboard engine on a boat can be taken from US 5,358,436. Said apparatus comprises a clamp bracket which can be fixed to the boat and a swivel bracket for supporting the outboard engine. A hydraulic cylinder, which is linked to the swivel bracket and the clamp bracket, is provided such that the outboard engine can be tilted up and down with respect to the boat. An electric motor and an oil pump are provided for driving said hydraulic cylinder, wherein said electric motor and said oil pump are positioned towards the bottom and the sides of said hydraulic cylinder. In said arrangement the cylinder as well as the electric motor and the oil pump are accommodated within the arms of the clamp bracket. Furthermore, in the prior art, power tilt apparatus are equipped with a manual valve 40, such as shown in Figure 16 that is connected into both the oil conduits 28, 29 that connect to the main valve 32 from the upper and lower oil chambers of the cylinder unit 20 of the hydraulic cylinder 13 in a manner such that the manual valve can be operated manually to return oil to the oil reservoir 15 through the respective connecting conduits 41, 42 and oil conduits 28, 29 in the event of equipment failure. A comparable hydraulic wiring arrangement of the power tilt apparatus can be taken from US 5,049,099. However, in order to ease the manually tilting of the outboard engine up and down using the manual valve device in conventional power tilt apparatus, as shown in Figure 16, the manual valve 40 must be connected in the connecting conduits 41, 42 from the oil conduits 28, 29. The manual valve 40 as shown in Figure 17 is rotated using a tool to make it possible to return the oil in both the oil conduits 28, 29 for the upper and lower cylinders to the reservoir tank 15. However, when considering the use of the manual valve for actually manually tilting the outboard engine, in the event of a breakdown of the electric motor, oil pump, etc., it is absolutely necessary that it be possible for the engine to be tilted down into the water by means of a manual valve if the boat is to be operated, but it was very seldom the case that the manual valve had to be operated to tilt the engine up out of the water. Thus, the prior art required a more complex hydraulic circuit of interconnecting oil conduits to provide both the manual tilt up and the manual tilt down capability without considering the frequency with which the respective operations would be performed. Further, in order to provide both the up and down tilt capability, the manual valve itself, as shown in Figure 17, had an internal oil conduit and a complicated structure and required a tool to operate, and the valve itself mitigated against making the apparatus more compact, drove up costs, and moreover, was bothersome to operate. It is an objective of the present invention to provide a power tilt apparatus for mounting an outboard engine on a boat having a simple and compact structure. According the present invention, said objective is solved by a power tilt apparatus for mounting an outboard engine on a boat having the features of independent claim 1. Accordingly, such a power tilt apparatus for outboard engines according to this invention does not require larger or heavier structures for the brackets that attach the outboard engine to the boat, and since the power tilt apparatus can be incorporated in the space between the respective brackets, it is possible to make the brackets more compact, thereby avoiding unnecessary cost increases. Furthermore, the power tilt apparatus may also be adapted to small outboard engines. The invention will be explained in greater detail hereinafter with respect to the appended drawings showing preferred embodiments thereof. Figure 1 shows a sketch of the power tilt apparatus used for outboard engines. Figure 2 shows a side view of an embodiment of the power tilt apparatus of this invention. Figure 3 shows a front view of the power tilt apparatus from the direction of arrow A of Figure 2. Figure 4 shows the position relationships between the hydraulic cylinder and the brackets in a transverse section taken along line B-B of Figure 3. Figure 5 shows a sectional view of the hydraulic cylinder used in the power tilt apparatus of Figures 2 and 3 Figure 6 shows a sectional view of the oil pump used in the power tilt apparatus of Figures 2 and 3. Figure 7 shows the hydraulic circuit used in the power tilt apparatus of Figures 2 and 3. Figure 8 shows a front sectional view of a conventional power tilt apparatus. Figure 9 is a sectional view of the hydraulic cylinders used in conventional power tilt apparatus: (A) shows an example of the junction by a seal between the outer cylinder and inner cylinder, and (B) shows an example of a mechanical junction between the outer cylinder and the inner cylinder. Figure 10 shows a sectional view of one example of an oil pump used in conventional power tilt apparatus. Figure 11 is a circuit diagram of one example of a hydraulic circuit used in conventional power tilt apparatus. Figure 12 shows an embodiment of the power tilt apparatus which does not show specific features of the brackets according to the subject matter of independent claim 1. Said power tilt apparatus of Figure 12 is equipped with the manual valve structure assembled between the swivel bracket and clamp bracket from the direction of arrow A in Figure 1. Figure 13 shows a partial sectional view inside the lower part of the hydraulic cylinder and the reservoir tank of the power tilt apparatus shown in Figure 12. Figure 14 shows a circuit diagram of the hydraulic circuit for the power tilt apparatus shown in Figure 13. Figure 15 shows a sectional view of the manual valve of the power tilt apparatus shown in Figure 13: (A) with the valve closed, and (B) with the valve open. Figure 16 shows a circuit diagram of a power tilt apparatus having a conventional manual valve structure. Figure 17 shows a sectional view of the structure of a conventional manual valve positioned in the hydraulic circuit of a power tilt apparatus. Figure 18 shows another embodiment of the manual valve structure in a power tilt apparatus according to this invention in a front view from the direction of arrow A in Figure 1 of the assembly between the swivel bracket and clamp bracket. A first implementation embodiment of a power tilt apparatus will be described below with reference to the figures. Figure 1 shows a simple diagram of an outboard engine employing a power tilt apparatus. The outboard engine 1 is attached to the rear stern plate 2 of the boat, and the drive source, the engine, is housed inside the top cowling 3 in the space formed by the top cowling 3 and the housing composed of the upper case 4 and lower case 5. The propeller 6 is attached at the bottom rear of the lower case, and when the boat is running, turning the steering handle 7 allows the engine to rotate in the horizontal plane around the steering shaft (not shown) as the axis of rotation. With regard to the attachment of the outboard engine 1 to the boat, a swivel bracket 9 supports the outboard engine 1 rotatably in the horizontal direction around the steering shaft, and the clamp bracket 10 makes it possible to removably attach the engine to the stern plate 2 of the boat. The two brackets 9, 10 are rotatably joined at their respective top ends by a tilt shaft 11 that serves as the rotational axis for tilting the engine up and down. Thus, the engine can be attached to or removed from the boat by means of the swivel bracket 9 and the clamp bracket 10. In order to use mechanical force rather than manual force to tilt the outboard engine 1 up out of the water or lower it into the water by the brackets 9, 10 that attach it to the boat's stem plate, the engine is equipped with a power tilt apparatus 12, which is composed of an oil pump driven by an electric motor and of an extending and retracting hydraulic cylinder that is attached between the swivel bracket 9 and the clamp bracket 10 that allows the outboard engine 1 to be tilted around tilt shaft 11 in the up-down direction with respect to the boat. Figures 2 and 3 show an embodiment of the power tilt apparatus 12 of this invention assembled between the swivel bracket 9 and the clamp bracket 10. Figure 2 shows an overall view from the right side and Figure 3 shows an overall view from the front (in the direction of arrow A in Figure 2). Figure 4 shows the positioning relationships between the hydraulic cylinder and the brackets from the direction along the B-B line in Figure 3. The power tilt apparatus 12 is assembled between the swivel bracket 9 and the clamp bracket 10, which are rotatably linked at their upper ends by a horizontally disposed tilt shaft 10, and the oil pump 16 contained in the reservoir 15 and the electric motor 14 are attached as an integral unit to the hydraulic cylinder 13 that spans the swivel bracket 9 and the clamp bracket 10. An upper attachment member 13a is formed at the upper end of the hydraulic cylinder 13 (the upper end of the piston rod) which is rotatably affixed axially to the horizontally disposed cylinder attachment shaft 9a at top of the swivel bracket 9, and the lower end, (the bottom of the cylinder unit) has an attachment member 13b rotatably affixed axially to the horizontally disposed cylinder attachment member 10a that is affixed to the bottom of the clamp bracket and spanning the top of the swivel bracket 9 to the bottom of the clamp bracket 10. The electric motor 14 is positioned sideways at right angles to the axial direction of the hydraulic cylinder 13 and the motor 14 is integrally attached to the bottom of the hydraulic cylinder 13 with the reservoir 15 housing the oil pump 16 being disposed between the motor and the hydraulic cylinder. As shown in Figure 4, since the swivel bracket 9 and the clamp bracket 10 only need to be wide enough to accommodate the width of the hydraulic cylinder 13, the widths of these brackets can be reduced without interfering with the electric motor 14 or the reservoir 15. Figure 5 shows a part of the hydraulic cylinder 13 used in the power tilt apparatus 12 of this embodiment. The hydraulic cylinder unit 20 is of the double cylinder type and is composed of an outer cylinder 21, inner cylinder 22 and cap member 23. The lower end of the piston rod 24 that moves in and out of the cylinder body and passes through the cap member 23 is affixed to the piston 25 that slides along the inside wall of the inner cylinder 22. The piston rod moves in and out of the cylinder body 20 in accordance with the up-down motion of the piston that is generated by the oil pressure difference between the upper oil chamber and the lower oil chamber inside the inner cylinder, thereby causing the hydraulic cylinder to extend and contract. The cap member 23 of the cylinder body 20 of the hydraulic cylinder 13 is screwed into threads on the inside circumference of the outer cylinder 21. A resilient gasket 126 fitting into a the stop area formed on the inside surface of the inner cylinder contacts the perimeter surface of the bottom of the cap member 23, and near the bottom edge of this resilient member (resilient gasket) 126, there is a step area 20a where the outer cylinder 21 and inner cylinder 22 make contact. The force exerted by the resilient member 126 causes the inner cylinder to make pressure contact at the step area 20a between the outer cylinder 21 and the inner cylinder 22, thereby holding the inner cylinder 22 in place with respect to the outer cylinder 21. Figure 6 shows the area of the oil pump 16, which is housed inside the reservoir 15, and which, in this embodiment of the power tilt apparatus 12, is mounted at the bottom of the hydraulic cylinder 13. The oil pump 16, which is formed by the structure of the gear pump, is composed of the two gears 131 and 132 that are disposed in parallel and that engage the gear which is directly machined on the output shaft 130 of the electric motor. The output shaft directly engages the gear 131 on the drive side. The gear area 133 for the various gears 131, 132 comprises the gear pump oil inlet. Figure 7 shows the hydraulic circuit for the power tilt apparatus 12 of this embodiment and is equipped with an oil pump 16 of the above described structure. As is shown in Figure 5, the cylinder 20 of the hydraulic cylinder 12 has a lower oil chamber and an oil inlet/outlet hole 127 which is open near the bottom end of the outer cylinder 21. Also, above that, an oil inlet/outlet hole 128 opens into the top of the inner cylinder 22, and, in the gap between the outer cylinder 21 and inner cylinder 22 an oil inlet/out hole 129 connects to the upper oil chamber. As shown in Figure 7, the oil inlet/outlet holes 127, 129 formed in the cylinder unit 21 are connected to oil lines 35, 36, respectively. A main valve 37 located between the oil pump 16 and the oil lines 35, 36 can automatically redirect the oil output from the oil pump 16. The oil lines 35, 36 are connected on respective sides of the main valve 37, and both sides of the main valve 37 are connected to both sides of the oil pump 16 by oil lines 38, 39. The direction of the oil output from the pump is changed by the forward or reverse operation of the oil pump 16, and the main valve 37 allows the direction of the oil flow through the hydraulic circuit to be changed. The oil lines 35, 36 run from the cylinder unit 20 to the main valve 37 and comprise an in-line manual valve 40, which, in the event of a breakdown of the electric motor or oil pump, can be operated manually to allow the oil to return to the reservoir 15. Also, a relief valve 41 is installed in the oil line 35 to handle the oil volume fluctuations in the cylinder unit that result from increasing temperature, and a relief valve 42 is installed in the oil line 39 that runs between the main valve 37 and the oil pump 16 to compensate for the down thrust force setting and the oil displacement of the piston rod. In the present embodiment, each of the valves 37, 40, 41 and 42 are incorporated inside the reservoir 15, and all the oil that leaks from the valves 40, 41 and 42 returns to the reservoir 15. The power tilt device 12 of this embodiment with the above described structure places the electric motor 14 and the reservoir 15 containing the oil pump 16 at the bottom of the hydraulic cylinder, making it possible to prevent interference between the brackets 9, 10 and the motor 14 or reservoir 15 (oil pump 16). Moreover, the brackets 9 and 10 need only be wide enough to accommodate the width of the hydraulic cylinder 13, thereby making it possible to minimize their size and to avoid massive, heavy bracket 9, 10 structures. Further, since the hydraulic cylinder 13 is attached at the centers of the respective brackets 9, 10, it is possible to eliminate the strength imbalance that results from the hydraulic cylinder being attached in an off-center position. This feature eliminates the need to reinforce the brackets 9, 10, thereby enabling the brackets 9, 10 to be lighter in weight and even more compact. Further, the transverse mounting of the electric motor 14 at the bottom of the hydraulic cylinder 13, with the reservoir 15 containing the oil pump 16 between them, facilitates affixing the bottom of the hydraulic cylinder to the various brackets 9, 10 without interference by the electric motor 14 or oil pump 16, thereby avoiding concerns over interference in assembly. Further, since the principal valves 37, 40, 41 and 42 located in the oil lines between the oil chambers inside the hydraulic cylinder and the oil pump can all be located inside the reservoir, it is possible to make the overall power tilt apparatus 12 very compact. However, with regard to the conventional power tilt apparatus as shown in Figure 9 (A), an O-ring or the like is generally used to form a seal 50 at the contact surface between the inner cylinder and outer cylinder at the base of the twin-cylinder type hydraulic cylinder in order to prevent oil leakage between the gap (oil passage) formed between the inner cylinder 21 and outer cylinder 22 and the lower oil chamber. Generally a groove is formed on the mating surfaces of either the outer cylinder 21 and the inner cylinder 21 to accommodate the seal 50, thereby facilitating the installation of the seal material in the grooves. This design, which entails the machining of a groove in either the outer cylinder 21 or the inner cylinder 22, reduces the wall thickness and diminish strength in these areas. As a result, it is necessary to increase the wall thickness of the outer cylinder 21 or the inner cylinder 22 to maintain adequate strength. As a result the hydraulic cylinder is heavier overall and cannot be made as compact as possible. On the other hand, as shown in Figure 9(B), it is possible to tightly affix the outer cylinder 21 to the inner cylinder using mechanical means without a seal. In cases where the outer cylinder 21 and the inner cylinder 22 are attached tightly together at the mating surface by mechanical means, the outer cylinder 21 and the inner cylinder 22 in particular must be made of special, more costly materials. In addition, expansion and contraction due to temperature changes can make the seal unreliable or loose. As opposed to such a design, the structure of the cylinder unit 20 of this embodiment shown in Figure 5 does not require a groove for the seal, and nor does it require the strong surface contact between the outer cylinder and inner cylinder that mechanical connection requires. The force generated by the resilient member 126 between the outer cylinder 21 and the inner cylinder 22 exerts pressure against the step 20a and holds it in place. This structure makes is possible to use thin walled inner and outer cylinders, thereby allowing the hydraulic cylinder to be more compact. Furthermore the resilient member 26 absorbs the dimensional changes from expansion and contraction without causing the seal to become unreliable or loose. Further, with respect to the gear pump structure used as the oil pump in conventional power tilt apparatus, and, as shown in Figure 10, the gears 131, 132 of the gear pump are composed of gears attached to shafts, and gear 131 on the drive side is located coaxially with the output shaft 130 of the electric motor 14, wherein the output shaft 130 from the electric motor 14 drives the gear 131 by means of a coupling 134. Since this type of gear pump design requires linking the gear pump gears 131, 132 by a coupling 134 to the output shaft 130 of the electric motor 14, the height of the oil pump 16 necessarily increases. Further the use of the coupling 134 requires higher precision gears such as the shafted gears, which increases costs. However, the oil pump 16 of this embodiment as shown in Figure 6 does not require a couplings, and accordingly, it may be made more compact in height. Further, costs can be held down because it needs fewer parts. Also, because it is not necessary to use special gears attached to shafts, the gears can be produced at lower cost using grinding, etc. Further, with regard to the oil inlet to the oil pump 16 from the reservoir in the hydraulic circuit in conventional designs, as shown in Figure 11, it is necessary to use respective inlet passages 43, 44 fitted with one-way valves 45, 46. It takes a bulky structure to accommodate the inlets for the oil intake structure, and the resulting higher number of parts increases costs for both materials and labor. Further, the operation of the oil pump can be diminished by oil leaks from the one-way valves 45, 46 that are caused by clogging, etc. By contrast, the oil inlet area of the embodiment shown in Figure 6, is located in the gear area 133 where the gears 131, 132 reside. As shown in Figure 7 because the oil inlet is located between the gears 131, 132 of the gear pump, and inside the reservoir 15, there is no need to equip the inlet with a one-way valve; thus, the structure has been simplified to make the apparatus more compact and less costly. The structure of the further embodiment according to figure 12 shows a power tilt apparatus which does not teach the specific features of the brackets according to the subject-matter of independent claim 1. Figure 12 shows the power tilt apparatus assembled between the swivel bracket 9 and the clamp bracket 10 from the front (in the direction shown by arrow A of Figure 1). The power tilt apparatus 12 is composed of a hydraulic cylinder 13, electric motor 14, and a reservoir tank 15 which houses an oil pump. The top end (top of the piston rod) of the hydraulic cylinder 13 has an attachment member 13a formed thereon that is rotatably supported axially on a horizontally disposed cylinder attachment shaft 9a affixed to the top of the swivel bracket 9. The bottom (the bottom of the cylinder unit) is rotatably supported axially on a horizontally disposed cylinder attachment shaft 10a that is affixed to the bottom of the clamp bracket 10. Thus, the cylinder spans from the attachment at the top of the swivel bracket 9 to the attachment at the bottom of the clamp bracket 10. The oil reservoir tank 15 which contains the oil pump is integrally attached to the lower side of the hydraulic cylinder 13 that spans the brackets 9 and 10, and the electric motor 14 is attached in series to the top of the reservoir tank 15. The overall power tilt apparatus is assembled between the brackets used to attach the outboard engine to the boat (between swivel bracket 9 and clamp bracket 10), the electric motor 14 and reservoir tank 15 extending parallel to the hydraulic cylinder. Figure 13 shows the internal parts of the lower portions of the hydraulic cylinder 13 and the reservoir tank 15 of the power tilt apparatus 12. An oil pump 16 is inside the reservoir tank 15 which is attached to the bottom of the hydraulic cylinder 13. Though not shown in the figure, the oil pump 16 is a gear pump, whereby the output shaft 17 of the electric motor 14 is linked by a coupling 18 to the drive side of the gear pump, and the rotation of the electric motor 14 thereby causes the oil pump 16 to be driven. The hydraulic cylinder 13 of the cylinder body 20 is of the double cylinder type, composed of an outer cylinder 21 and inner cylinder 22 with their ends covered by a cap member 23. The upper end of a piston rod 24, inserted through the cap member 23, slides inward and outward, while the lower end of the piston rod 24 is attached to a piston 25 that is in sliding contact with the inner wall of the inner cylinder 22 of the cylinder body and that divides the inside of the cylinder body into the upper oil chamber and lower oil chamber. An oil inlet/outlet opening 26 is located at the bottom and an oil inlet/outlet opening 27 is located above it, both in the outside cylinder 21. The lower oil inlet/outlet 26 passes into the lower chamber of the inside of the cylinder unit, and by means of an oil inlet/outlet (not shown) formed at the top of the inner cylinder, the upper oil inlet/outlet 27 that passes into the space between the outside cylinder 21 and the inside cylinder 22 connects with the upper oil chamber in the cylinder unit 20. The lower oil inlet/outlet 26 in the cylinder unit 20 is connected to the reservoir tank 15 by an oil conduit 28 formed therein, and the upper oil inlet/outlet 27 is connected by an oil conduit 29 formed in the reserve tank in a manner such that oil pressure differentials between the upper oil chamber and the lower oil chamber created by pumping oil through one or the other of the oil conduits 28, 29 cause the extension and retraction of the piston rod 24 from the cylinder unit 20 based upon the upward or downward motion of the piston 25, to thereby extend or retract the hydraulic cylinder 13. At the bottom end of the reserve tank on the side of the hydraulic cylinder 13 having the foregoing structure, there is a manual valve 30 that is operated by a push button 30a installed in the oil conduit 28 that is formed in the reservoir tank 15 and an oil return conduit 31 thereby links the oil conduit 28 back to the reservoir tank 15 through the manual valve 30. Figure 14 shows the hydraulic circuit for the above described power tilt apparatus 12 that is equipped with an oil pump 16 and a manual valve 30. The oil conduit 28 that connects with the lower oil chamber and the oil conduit 29 that connects with the upper oil chamber of the hydraulic cylinder are each connected through the main valve 32 and the oil conduits 33, 34 to the output of the oil pump 16, which can be operated in forward or reverse. The direction of the oil flow through the hydraulic circuit can be changed by means of the main valve 32, which automatically redirects the oil output of the oil pump 16. The structure of this power tilt apparatus 12 is shown in Figure 13 and is composed of an oil conduit 28 which connects to the lower oil chamber of the cylinder unit 20 and to the main valve 32, and a manual valve 30 is installed between that oil conduit 28 and the oil return conduit 31 to the reservoir tank 15 so that, when a push button 30a is pressed, the manual valve 30 returns oil from the oil conduit 28 into the reservoir tank 15. As is shown in Figure 15(A), this manual valve 30 includes a ball valve member that is located in the oil conduit continuing from the oil conduit 28 to the oil return conduit 3 land that ball member is maintained in the closed position due to the oil pressure on the side of the oil conduit 28. When the button is pushed, as shown in Figure 15 (B), the ball valve overcomes the resistance from the oil pressure in the oil conduit 28 and opens, allowing the oil in oil conduit 28 to flow through the return conduit 31. Further a relief valve 35 installed in the hydraulic circuit of the power tilt apparatus between the lower oil chamber of the cylinder and the main valve takes care of any oil volume fluctuations that result form rising oil temperatures inside the cylinder unit 20. Another relief valve 36 installed in the oil conduit 34 between the main valve 32 and the oil pump 16 compensates the down thrust force setting and the displacement of the piston rod. Oil depleted from the hydraulic circuit and that has been returned to the reservoir tank 15 from the valves 30, 35 or 36 is once again introduced into the inlets of the oil pump 16 which are equipped with one-way valve 37, 38 to replenish the oil in the hydraulic circuit from the reservoir tank 15. Thus, compared to the conventional manual valve structure that is shown in Figure 16, the manual valve structure in this embodiment of the power tilt apparatus 12, as described above, does not require the connecting conduits 41, 42 from the oil conduits 28 and 29, thus making it possible to simplify the hydraulic circuit for the power tilt apparatus, and to make it more compact. Further, the manual valve 30 itself uses a push button 30a to open and close a ball valve, which, compared to the structure of the conventional manual valve shown in Figure 17, is of simpler structure. In addition, bothersome operations using tools are not required to operate the valve, it is operated merely by depressing of the push button 30a with the finger (and releasing the push button 30a), thereby easing the operation of the manual valve 30. Further, because this embodiment locates the manual valve at the lower end area of the hydraulic cylinder (at the bottom of the reservoir tank), it is possible to minimize the length of the conduit that runs from the lower chamber of the hydraulic cylinder 13 through the oil inlet/outlet 26, through the oil conduit 28, and through the return conduit 31. The foregoing explanation relates only to an embodiment of a power tilt apparatus according to the subject-matter of independent claim 1. For example, as shown in Figure 18, it is possible to adapt the related teaching to a different type of power tilt apparatus (The actual structure of the manual valve shown in the embodiment of Figure 18 does not differ substantially from the above described manual valve 30, and further explanation of it will be omitted.) The power tilt apparatus shown in Figure 18 is one in which the rotating shaft of the electric motor 14 is transversely placed at right angles to the axial conduit of the hydraulic cylinder. It is attached integrally at the bottom of the hydraulic cylinder to the reserve tank 15 that contains the oil pump 16, positioned between them. In this power tilt apparatus, it is possible to minimize the width of the brackets 9 and 10 since they need only accommodate the width of the hydraulic cylinder, and because the electric motor 14 and reserve tank 15 do not interfere with the brackets 9, 10, it is possible to avoid having to make the brackets 9, 10 larger to accommodate the power tilt apparatus. Also, since the hydraulic cylinder is centered within the brackets 9 and 10, it is possible to avoid making the brackets larger and heavier because of the required reinforcement when the hydraulic cylinder 13 is offset with respect to the brackets 9, 10.

Claims: Power tilt apparatus for mounting an outboard engine (1) on a boat, said apparatus comprising: a clamp bracket (10) adapted to be fixed to the boat, a swivel bracket (9) for supporting the outboard engine (1), and a hydraulic cylinder (13) which is linked to a top end of the swivel bracket (9) and a bottom end of the clamp bracket (10) to enable the tilting of the outboard engine up and down with respect to the boat, an electric motor (14) and an oil pump (16) for driving said hydraulic cylinder (13), wherein said electric motor (14) and said oil pump (16) are positioned toward the bottom and to the side of the hydraulic cylinder (13), characterized in that the width of the brackets (9,10) is narrowed in view of the width of the hydraulic cylinder (13) to allow only said hydraulic cylinder (13) to be accommodated between the brackets (9,10). Power tilt apparatus according to claim 1, characterized in that the swivel bracket (9) comprises a substantially V-shaped portion for accommodating at least an upper portion of said hydraulic cylinder (13) when the hydraulic cylinder (13) assumes a retracted state, whereat side flanges of said swivel bracket (9) extend between side flanges of the clamp bracket (10). Power tilt apparatus according to claim 1 or 2, characterized in that the electric motor (14) is mounted near the lower end of the hydraulic cylinder (13) where said hydraulic cylinder (13) is connected with the clamp bracket (10) in a manner such that its rotating shaft lies at a right angle to the axial line of the hydraulic cylinder (13), and wherein a reservoir (15) that contains the oil pump (16) is located between the hydraulic cylinder (13) and the electric motor (14). Power tilt apparatus according to claim 3, characterized in that an oil line that connects an oil chamber of the hydraulic cylinder (13) and the oil pump (16) includes a main valve which is installed inside the reservoir (15). Power tilt apparatus according to one of claims 1 to 4, characterized in that an output shaft of the electric motor (14) comprises a gear (130) directly machined thereon and is positioned parallel to gears (131,132) of the oil pump (16). Power tilt apparatus according to one of claims 1 to 5, characterized in that the carrier areas of the gears (131,132) of the oil pump (16) form an oil inlet member of the oil pump.

Inventors: UEMATSU YOSHIKATSU, UEMATSU, YOSHIKATSU, Uematsu, Yoshikatsu c/o SOQI Kabushiki Kaisha
Applicants: SOQI KK, SOQI KABUSHIKI KAISHA
Application year: 1999
Main classification: B63H20
IPC codes: F15B20, B63H20, F15B13, F02B61