Hydro-tilt for an outboard engine

Abstract: A hydro-tilt apparatus for an outboard engine (1) comprises a manual valve (20) to open and close an oil passage between an upper oil chamber and a lower oil chamber of a hydraulic cylinder (13) and a gas chamber (19) that compensates for the oil displaced by the piston rod (18) as it retracts into and extends out of the cylinder (13). The manual valve (20) and the gas chamber (19) are positioned in series with each other, parallel to and alongside the cylinder (13). Thus, the hydro-tilt apparatus secures adequate capacity for the gas chamber (19) and has a compact structure in length and width which is well suited for use on small outboard engines (1). The manual valve (20) comprises two one-way valves (31,32) coupled via a spring (33). A means for operating said one-way valves (31,32) is capable of operating said valves in three modes: both valves closed, one valve open and one closed, and both valves open.

Description: The present invention relates to a hydro-tilt apparatus for an outboard engine according to the preamble part of the independent claim 1. In the past, outboard engines for small boats have been attached to the stem plate of the boat by a clamp bracket, and were rotatably supported by a swivel bracket that allowed turning the outboard engine in the horizontal plane. A hydraulic cylinder that can extend and retract freely by means of the operation of a manual valve was positioned between the brackets to constitute the hydro-tilt apparatus. The top ends of the swivel bracket and clamp bracket are rotatably linked by a horizontally disposed tilt shaft around which they can rotate to allow manually tilting up and down the outboard engine. To wit, when the manual valve of the hydro-tilt apparatus is opened, the hydraulic cylinder of said apparatus operates in a free state wherein the outboard engine may be manually tilted up or down. In addition, when the outboard engine reaches the desired tilted up or down position, the manual valve of the hydro-tilt apparatus can be closed to retain the engine in that position by means of said hydraulic cylinder case holding the outboard engine in place. Figures 7 and 8 show this type of conventional hydro-tilt apparatus used on outboard engines. One end of the piston rod 18 is connected to a piston 15 which separates the inside the cylinder case 14 into an upper oil chamber and lower oil chamber, and a gas chamber 19 has been installed to compensate for the amount of oil displaced by the extension and retraction of the piston rod 18 with respect to the cylinder case 14. In addition, a manual valve 20 is installed to open and close the oil passage 21 that connects the upper oil chamber with the lower oil chamber in the cylinder. However, the above described hydro-tilt apparatus for outboard engines, as shown in Figure 7, places the gas chamber 19 on the side of the cylinder case 14, and a manual valve 20 to open an close the oil passage 21 that connects the upper oil chamber to the lower oil chamber is located on the other side of the cylinder 1, opposite the side where the gas chamber is mounted. This structure makes the apparatus wider overall. On the other hand, as shown in Figure 8, the hydro-tilt apparatus for outboard engines places the gas chamber 19 above the oil chamber inside the cylinder case 14 wherein the gas chamber 19 unit is configured atop the oil chamber. While this structure is not too wide, the capacity of the gas chamber 19 is low and the overall apparatus is longer. Accordingly, in either case, there is a disadvantage of mounting such hydro-tilt apparatus to small outboard engines for small boats because of the need to either lengthen or widen the overall apparatus to obtain adequate gas chamber capacity. US-A-5,368,509 discloses a hydraulic-tilt lock mechanism for a marine outboard motor. The tilt lock mechanism comprises a main cylinder part defining a cylinder bore in which a piston rod is slidably supported. The piston defines an upper oil chamber and a lower oil chamber which are connected to each other by a control valve assembly. Furthermore, an accumulator assembly comprising a chamber filled with hydraulic fluid and gas is formed integrally with the cylinder housing of the hydraulic-tilt lock mechanism. Here, the control assembly is arranged between the cylinder housing of the tilt lock mechanism and the accumulator assembly. Moreover, US-A-5,389,019 relates to a control assembly for controlling the position of an outboard drive which is similar to the hydraulic tilt-lock mechanism disclosed in US-A-5,368,509, wherein a control valve assembly is arranged at the bottom of an accumulator chamber. Furthermore, oil passages for connecting the accumulator chamber and the oil chambers of the cylinder have been arranged between the cylinder and the accumulator chamber and under the accumulator chamber, so that the size of the entire assembly has been increased. It is an objective of the present invention to improve a hydro-tilt apparatus for an outboard engine as indicated above so as to be compact in length and width, and to be easy to use on small outboarb engines. The objective is solved according to the present invention by a hydro-tilt apparatus for an outboard engine comprising the features of claim 1. Accordingly, there is provided a hydro-tilt apparatus allowing a sufficient volume for the gas chamber but avoids increasing the overall length or width of the apparatus thereby making the hydro-tilt apparatus particularly well suited for use on small outboard engines. With regard to either of the examples of conventional hydro-tilt apparatus for outboard engines shown in Figure 7 or 8, the manual valve 20 has only two operational positions which set the hydraulic cylinder either in a free mode when the valve is open, or in a fixed mode when the valve is closed. To tilt up the outboard engine, the manual valve must be open. As a result, if the up-tilt operation is halted midway, because the hydraulic cylinder remains in the completely free mode (free to extend or retract), the engine will fall back of its own weight. Thus it is necessary to switch the manual valve to "closed" in order to hold the outboard engine in place when one requires a pause during the up-tilt operation and when the engine has been tilted to its desired position. To avoid the bothersome nature of this tilting up the engine, it would be desirable for the manual valve to have a design allowing to set the hydraulic cylinder in a fixed mode to affix the outboard engine, to put the hydraulic cylinder in a free mode (free to extend or retract) to allow the outboard engine to be tilted down (or up), and to have a third mode that only allows extension of the hydraulic cylinder so the outboard engine may be tilted up without it being able to drop back. According to a preferred embodiment, the control valve, preferably a manual valve, comprises two one-way valves facing in the opposite direction which are positioned so as to be able to close the oil passage, each one-way valve having a closure member wherein a common spring is compressed between said closure member and exerts forces in opposite directions and a means for operating the two one-way valves which is capable of operating them in stages to displace just one closure member or both closure members thereby allowing the control valve to be switched in three stages: both valves closed, one valve open and one closed, and both valves open. The new control valve structure is very compact in size and inexpensive. Further, it allows three way switching including a free mode, a fixed mode and a mode wherein passage of a pressure medium is possible only in one direction. It is evident that this control valve which preferably is a manually operated valve can be used not only in hydro-tilt apparatus. Moreover, it is also applicable in hydro-tilt apparatus which do not show a gas chamber but only an oil passage connecting a first and second oil chamber of the cylinder. Further advantageous embodiments of the invention are laid down in the further subclaims. In the following, the present invention is explained in greater detail by means of several embodiments thereof in conjunction with the accompanying drawings, wherein: Figure 1 is a diagram of an outboard engine equipped with the hydro-tilt apparatus of this invention. Figure 2 is a front view from the direction of arrow A of Figure 1 showing an embodiment of a hydro-tilt apparatus according to this invention assembled between the swivel bracket and clamp bracket. Figure 3 is a sectional view from the reverse direction of arrow A of Figure 1 showing the internal structure of the hydro-tilt apparatus shown in Figure 2. Figure 4 is an explanatory figure showing the operational states of the manual valve while in the closed state in the hydro-tilt apparatus shown in Figure 3: (A) the operational state of the first cam member, (B) the operational state of the second cam member, and (C) the operational state of me ball valves with respect to the oil passage. Figure 5 is an explanatory figure showing the operational states of the manual valve while in the one-way valve state in the hydro-tilt apparatus shown in Figure 3: (A) is the operational state of the first cam member, (B) is the operational state of the second cam member, and (C) is the operational state of the ball valves with respect to the oil passage. Figure 6 is an explanatory figure showing the operational states of the manual valve while in the open state in the hydro-tilt apparatus shown in Figure 3: (A) is the operational state of the first cam member, (B) is the operational state of the second cam member, and (C) is the operational state of the ball valves with respect to the oil passage. Figure 7 is a sectional view of a prior art embodiment of a hydro-tilt apparatus. Figure 8 is a sectional view of another prior art embodiment of a hydro-tilt apparatus. An embodiment of the hydro-tilt apparatus of this invention will be described below with reference to the figures. Figure 1 is a diagram that shows an embodiment of an outboard engine that employs a hydro-tilt apparatus according to this invention. The outboard engine 1 is attached to the stem plate 2 of the boat, with the engine drive means being housed inside the top cowling 3 in a housing formed by the top cowling 3, the upper case 4 and the lower case 5. The propeller 6, which constitutes the propulsion device, is attached at the rear of the upper case, in a manner such that when the boat is cruising, the steering handle 7 can be used to steer it in the horizontal direction around the steering shaft (not shown). The outboard engine 1 is attached to the boat by a swivel bracket 9, which allows turning the engine in the horizontal direction around the steering shaft, and a clamp bracket 10 which removably attaches it to the stern plate 2 of the boat. The top ends of the brackets 9, 10 are rotatably joined by a horizontally disposed tilt shaft 11. Thus, the outboard engine 1 can be turned in the horizontal direction by the swivel bracket 9 and be tilted up and down around the tilt shaft. Further, the outboard engine may be attached and removed from the boat by means of these brackets 9, 10. Using the hydro-tilt apparatus 12 makes it possible for an operator to manually tilt to the desired up or down position the outboard engine 1 that is attached to the stem plate 2 of the boat by the brackets 9, 10 and to affix it in place, a manual valve operated by a lever 12a can be switched open and closed to cause the hydraulic cylinder that is disposed between the swivel bracket 9 and the clamp bracket 10 to switch between the free state (where it can freely extend or contract) and the stationary state. Figure 2 shows the hydro-tilt apparatus 12 assembled between the swivel bracket 9 and the clamp bracket 10. The figure shows a view of the hydro-tilt apparatus taken from the direction of arrow A of Figure 1 wherein an upper attachment member 13 a formed on the top end of the hydraulic cylinder case (the top of the cylinder case) is rotatably supported at the top of the swivel bracket 9. An attachment member 13b formed on the bottom end of the hydraulic cylinder case (the bottom end of the piston rod) is rotatably supported at the bottom of the clamp bracket 10, thereby attaching the hydraulic cylinder case to extend from the top of the swivel bracket 9 to the bottom of the clamp bracket 10. Figure 3 is a view from the opposite direction of arrow A in Figure 1 which shows the internal structure of the hydro-tilt apparatus 12 that is installed as described above between the brackets 9 and 10. The hydro-tilt apparatus 12 has an integral structure and is composed of a hydraulic cylinder 13 comprising a cylinder case 14 and piston 15 (stationary piston 16 and free piston 17) and a piston rod 18, further of a gas chamber 19 which compensates for the oil displaced by the piston rod as it extends and retracts with respect to the cylinder, and of a manual valve 20 that opens and closes an oil passage that connects the upper oil chamber with the lower oil chamber inside the cylinder 13. To wit, the hydro-tilt apparatus 12 of this invention places the gas chamber 19 alongside of the cylinder case 14, and the manual valve 20 is located atop the gas chamber 19 and alongside the top part of the cylinder case 14. Thus the cylinder case 14, the gas chamber 19 and the manual valve 20 are all integrated inside one housing into one compact integral unit. Thus, compared to the conventional example shown in Figure 7 wherein the gas chamber 19 and the manual valve 20 are both located on the ends of the cylinder 14, the apparatus 12 can be more compact in width and still offer adequate capacity of the gas chamber 19, and compared to the conventional example shown in Figure 8, where the gas chamber is placed above the cylinder 14, the device is more compact in length. The lower end of the cylinder case 14 that is used as the hydraulic cylinder 13 of the hydro-tilt apparatus 12 is closed by a cap 14a through which the piston rod has been slidably inserted. The top of the piston rod 18 connects to the piston 15 (fixed piston 16 and free piston 17) which separates the upper oil chamber from the lower oil chamber inside the cylinder case 14. An oil inlet/outlet hole 22 formed in the top area of the side wall of the cylinder case 14 connects the upper oil chamber with the manual valve 20, and, beneath that hole, an oil inlet/outlet hole 23 connects the lower oil chamber with the gas chamber 19. In this embodiment of the hydro-tilt apparatus 12, there is a resilient member (disk spring) 24 that can extend and contract in the axial direction of the cylinder case 14 installed on the top surface side of the lid member 14a inside the cylinder case 14 that serves to prevent the cylinder case 14 from breaking due to oil pressure generated by the thermal expansion of the oil when the hydraulic cylinder 13 is in the fully extended position. Thus, when the hydraulic cylinder 13 is extended to its maximum length, the bottom surface of the piston 15 (fixed piston 16) rests in contact with the resilient member 24. In addition, should the oil expand due to elevated temperatures at this point, the resilient member 24 will be pressed downward by the piston 15 to accommodate that expansion. In addition, accompanying the downward motion of the piston 15, the oil in the lower oil chamber escapes into the gas chamber 19 to also prevent the destruction of the cylinder from the thermal expansion of the oil. With regard to such temperature compensation means for the hydraulic cylinder 13 that employ the resilient member 24, an oil escape passage is formed in the housing which connects to the oil chamber inside the cylinder 14 and to the gas chamber 19, however, with this structure, there is no need to install a separate relieve valve. The compensation for the temperature in the hydraulic cylinder is thereby made to be simpler and more compact. With regard to the oil passage that connects the upper oil chamber to the lower oil chamber inside the cylinder 14 of the hydro-tilt apparatus 12, the oil passage is formed on the side of the cylinder 14 and connects from the oil inlet/outlet on the side of the upper oil chamber to the manual valve 20, and then, through a pipe-like passage 25 in the gas chamber 19, from the bottom of the gas chamber 19 to the oil inlet/outlet in the side of the lower oil chamber. Because the pipe-like passage 25 is formed inside the gas chamber 19 as a part of the oil passage that connects the upper oil chamber to the lower oil chamber in the cylinder, there is no need to form an oil passage in the housing of the apparatus 12. The simple operation of inserting a pipe passage inside the gas chamber 19 allows easy formation of the oil passage and contributes to the simplicity and compactness of the apparatus. In this embodiment, a pipe-like passage 25 runs from the oil inlet/outlet hole 22 at the side of the top oil chamber through the manual valve 20 and to the inside of the gas chamber 19. An oil passage formed along the outside of the cylinder case 14 runs from the inside of the gas chamber 19 at its bottom to the oil inlet/outlet hole 23 on the side of the lower oil chamber. With regard to the manual valve 20 used to open and close the oil passage of the present embodiment of the hydro-tilt apparatus 12, as shown in Figures 1 and 2, this manual valve 20 is rotatably supported by a lid-shaped base plate affixed to the housing of the apparatus 12; the operating shaft 28 can be operated manually by lever 12a. A first cam member 29 is integrally affixed to the operating shaft 28, and a second cam member 30 is rotatably supported coaxially on the operating shaft 28, at some distance from the first cam member 29. Then, with regard to the one side and other side of the oil passage that is divided by the cam member 29, 30, when the two one-way valves facing in opposite directions completely close the oil passage, a common spring 33 compressed between two ball valves 31, 32 applies force in opposite directions against the first ball valve 31 and the second ball valve 32 to close the oil passage. Then, when the ball valves 31, 32 are displaced by the movements of the respective cam members 29, 30, one or the other side is retained in place by the cam member. Thus, with the above described structure for the manual valve, the rotation of the operating shaft 28 will cause one of the following conditions: both ball valves close their respective oil-passage sides so that no oil can flow through either side; both ball valves 31, 32 open to allow oil flow in both directions; and one or the other of the ball valves 31, 32 open one side of the oil passage to allow oil to flow in one direction or the other. When the second ball valve 32 closes the oil passage, the second ball valve 32 functions as a one-way valve, thereby making it possible to switch among three positions. Thus, three-way switching allows the first ball valve 31 to open the oil passage and the second ball valve 32 to close the oil passage to cause the second ball valve 32 to function as a one-way valve. With regard to the switching of this manual valve 20, Figure 4 shows the manual valve 20 in the closed condition. Figure 5 shows the manual valve 20 open in the one-way direction, and Figure 6 shows the manual valve 20 in the open condition. As is shown in Figure 4 (A) and (B), the rotational excursions of the first cam member 29 and of the second cam member 30 of the manual valve are restricted by stop 34. An engagement projection 29a formed to project from the surface of the first cam member 29 loosely enters an engagement hole 30a formed in the second cam member 30, and a spring 35 disposed between the engagement projection 29a and the engagement hole 30a exerts a counter-clockwise force upon the second cam member 30 with respect to the first cam member 29. Then, as shown in Figure 4 (A), when the operating shaft 28 is turned counterclockwise (with respect to the plane of the paper, hereinafter the same) until the first cam member 29 affixed to the operating shaft 28 is stopped by the stop 34, as shown in Figure 4 (B), the second cam member 30 is also pushed in the counterclockwise direction by the spring 35 by the engagement projection 29a of the first cam member until the rotation in conjunction with the first cam member 29 is prevented by the stop 34. The result, as shown in Figure 4 (C), is that the ball valves 31, 32, held in the respective cam members 29, 30, close the respective oil passages by closing the manual valve 20. Then, from that closed valve state, if the operating shaft is rotated through the prescribed angle in the clockwise direction, as shown in Figure 5 (A), while the first cam member 29 that is affixed to the operating shaft 28 rotates clockwise through the prescribed angle, then, as shown in Figure 5 (B), the second cam member 30 does not rotate, but is held against the stop 34 by the force of the spring 35. As a result, as shown in Figure 5 (C), the first ball valve 31 retained in the first cam member 29 moves to open the oil passage, but the second ball valve 32 retained in the second cam member 30 does not move and it continues to hold the oil passage closed. Accordingly, the second ball valve 32 functions as a one-way valve that in turn makes it possible for the manual valve 20 to function as a one way valve to allow the oil to flow in one direction. Further, if from this one-way valve state, the operating shaft 28 is rotated further in the clockwise direction, as shown in Figure 6 (A), the operating shaft is rotated clockwise until the stop 34 prevents further rotation of the first cam member 29 attached to the operating shaft, then, as shown in Figure 6 (B), the engagement projection 29a of the first cam member 29 causes the second cam member 30 to be pushed in the clockwise direction and to rotate in conjunction with the clockwise rotation of the first cam member 29. As a result, as shown in Figure 6 (C), the first ball valve 31 that is retained in the first cam member 29 is open over the oil passage, and additionally, the second ball valve 32 that is retained in the second cam member 30 is open over the oil passage, thereby keeping the manual valve 20 in the open state wherein oil can flow in either direction. When the manual valve 20 is switched in the manner described above to open it to render the hydraulic cylinder 13 completely free (free to extend or retract), the outboard engine can be freely tilted up or down. Also, when the manual valve 20 is in the closed state, the hydraulic cylinder 13 remains fixed. This feature securely fixes the position of the outboard engine. By putting the manual valve 20 in the one-way valve state, it is possible to tilt the outboard engine 1 upward, and even if the operator stops tilting it midway, the outboard engine 1 is held in place and will not tilt down from its own weight. Further, the oil passage that connects the upper oil chamber to the lower oil chamber inside the cylinder case 14 is formed as a pipe-like passage inside the gas chamber 19. This structure eliminates the need to form a special oil passage in the housing of the apparatus 12 and facilitates the formation of the oil passage inside the pipe by merely requiring the insertion of the pipe, thereby simplifying the apparatus and allowing it to be more compact. Further, because the present embodiment places a resilient member 24 inside the cylinder case 14 and because the gas chamber 19 and the oil chamber inside the cylinder case 14 are connected by a relief valve consisting of an oil escape passage formed in the housing, there is no need to install a separate relief valve to compensate for me temperature of the hydraulic cylinder, and this feature too makes the apparatus simpler and more compact. The foregoing explanation has been for a single embodiment of the hydro-tilt apparatus according to this invention, but the invention is not confined to this embodiment. For example, the manual valve 20 is not limited to the embodiment having this specialized structure, it is possible also to use a conventional opening and closing valve as the manual valve or make other appropriate design changes. As was explained above, the hydro-tilt apparatus for outboard engines of this invention allows a sufficient volume for the gas chamber and avoids increasing the overall length or width of the apparatus, thereby making the hydro-tilt apparatus well suited for use on small outboard engines. Further, since the three-way switchable manual valve is composed of two one-way valves (ball valves 31, 32 and spring 33) which can be switched to a one-way valve configuration by the rotation of the operating shaft and the operation of respective cams 29, 30, the manual valve is easy to operate, compact, and lowcost. The foregoing explanation was for only one embodiment of the manual valve structure in a hydro-tilt apparatus according to this invention, which is not confined to the above described embodiment. For example, the hydro-tilt apparatus using the manual valve is not confined to having the structure shown in the above embodiment, It is possible to adapt the valve to other types of hydro-tilt apparatus, or make other appropriate design changes.

Claims: Hydro-tilt apparatus for an outboard engine, comprising: a cylinder case (14) having a cylinder (13), a piston (15) accommodated in said cylinder (13) and separating a first oil chamber and a second oil chamber in said cylinder (13), a control valve (20) arranged in an oil passage connecting said first and second oil chamber, wherein a gas chamber (19) is provided for compensating for the oil displaced by a piston rod (18) of said piston (15), wherein said control valve (20) and said gas chamber (19) are positioned in series with each other and parallel to and alongside said cylinder (13), characterized in that said control valve (20) is located atop said gas chamber (19), and said oil passage is formed alongside said gas chamber (19), both being integrated inside one housing into one compact integral unit. Hydro-tilt apparatus according to claim 1, characterized in that said gas chamber (19) is integrally formed in said cylinder case (14). Hydro-tilt apparatus according to claim 1 or 2, characterized in that said control valve (20) is a manually operated valve. Hydro-tilt apparatus according to one of claims 1 to 3, characterized in that said oil passage to said upper and lower chambers inside said cylinder (13) is formed as a pipe-like passage (25) inside said gas chamber (19). Hydro-tilt apparatus according to one of claims 1 to 4, characterized in that said structure of said hydraulic cylinder case (14), when extended to its maximum length, is such that the end of said cylinder case (14) and said piston (15) are in indirect contact by a resilient member (24) that can expand and compress in the axial direction of said cylinder case (14). Hydro-tilt apparatus according to one of claims 1 to 5, characterized in that said control valve (20) comprises two one-way valves (31,32) facing in the opposite direction which are positioned so as to be able to close said oil passage, each having a closure member, wherein a common spring (33) is compressed between said closure members and exerts forces in opposite directions, and a means for operating the two one-way valves (31,32) which is capable of operating them in stages to displace just one closure member or both closure members, thereby allowing said control valve (20) to be switched in three stages: both valves closed, one valve open and one closed, and both valves open. Hydro-tilt apparatus according to claim 6, characterized in that said means for operating said valves comprises a first cam (29) affixed to a rotatable shaft (20), a second cam (30) located coaxially which can rotate through a prescribed range with respect to the first cam (29), a spring (35) which exerts force upon said second cam (30) to rotate it in a single direction with respect to said first cam (29), wherein said cams (29,30) and said spring (35) are arranged in such a manner with respect to said closure members of said valves (31,32) that said first cam (29) holds one closure member over a part of its rotational range, and that the rotational movement of said second cam (30), which holds the other closure member, is linked to that of said first cam (29). Hydro-tilt apparatus according to claim 7, characterized in that said means for operating said valves comprises a common stop member (34) for limiting the range of rotation of both cams (29,30). Hydro-tilt apparatus according to one of claims 6 to 8, characterized in that said one-way valves (31,32) are ball valves, each having a ball as its closure member. Hydro-tilt apparatus according to one of claims 6 to 9, characterized in that said first cam (29) has an engagement projection (29a), which enters an opening (30a) in said second cam (30) in a manner such that said projection (29a) may slide in the rotational direction over a prescribed angle of rotation.

Inventors: SAITO HIDEKI, SAITO, HIDEKI, Saito, Hideki c/o SOQI K.K.
Applicants: SOQI K K, YAMAHA MARINE KK, SOQI K.K., YAMAHA MARINE KABUSHIKI KAISHA
Application year: 1999
Main classification: B63H20
IPC codes: F15B1, F15B15, F02B61, B63H20