FIELD OF THE INVENTION This invention relates to the field of hydraulic amplifiers and to the use of a hydraulic amplifier to pro¬ vide higher pressure and force to move objects such as an outboard propulsion assembly in a marine drive.

BACKGROUND OF THE INVENTION Hydraulic trim tilt systems for outboard propul¬ sion units are well-known. Further, such systems' units employing a single cylinder to displace the propulsion system such as rotating them through an arc are well-known. One such example is shown in U. S. patent No. 3,799,104.

U. S. patent No. 3,842,789 also shows a system for using a single cylinder for power trim and tilt. Patent No. 4,064,824 and 4,096,820 both show systems for applying hydraulic forces to separate trim and tilt cylinders. Other patents showing hydraulic systems used with marine propulsion units are 3,885,517; ^' 3,434,450 and 3,434,448.

All of the prior systems, U. S. patent No. 3,842,789 being an example, require a particular valving arrangement to change the amount of hydraulic pressure to the actuator and to rotate the propulsion unit through the trim and tilt range. In that patent, manual adjustment of a valve in the hydraulic supply lines is required. Although the object of this patent and of other patents is to provide a higher pressure to a system when requiring greater force and less rapid movement during trim opera¬ tion and a lower pressure and more rapid movement during

tilt operation, the prior devices either require separat actuator cylinders to rotate the propulsion unit through trim and tilt, or require special hydraulic switching sy tems to change the distribution area or the hydraulic fl in the actuator.

DISCLOSURE OF THE INVENTION This invention is a hydraulic system for movin displacing or rotating a load for example, such as in a marine propulsion unit through its trim range and throug tilt range. In the trim range, when the boat is underwa and the angle of propulsion unit must be adjusted, a con derably greater force is required to displace the propul sion unit then to tilt it out of the water when power is removed. The trim range is limited with respect to the range of movement for the hydraulic propulsion unit. Du ing trim, hydraulic fluid is provided to the hydraulic cylinder actuator unit with greater pressure and force a with a resultant slower movement of the hydraulic cylind and the propulsion unit. _ Accordingly, this invention uses a hydraulic amplifier which is connected in the hydraulic circuit between the hydraulic pump and the hydraulic cylinder ac ator unit. The amplifier increases the pump pressure during the trim operation as necessary to increase the force to the hydraulic actuator connected to the propuls unit. At the end of the trim range and start of the til range, the amplifier is bypassed and further displacemen of the propulsion unit is then in the tilt range where t propulsion unit is then rapidly lifted clear of the wate The hydraulic amplifier includes a displaceabl or movable means which may be a piston and which has a d placement proportional to the displacement of the hydrau actuator cylinder and the propulsion unit in the trim range. Movement of the piston within the amplifier to o end of its displacement path may correspond to movement the propulsion unit to the end of its trim range and to start of its tilt range. ^'

At this point, a switch means such as a valve within the hydraulic amplifier and which may be mounted on the piston, bypasses the amplifier and connects the fluid from the hydraulic pump directly through to the actuator unit. The valve may be made responsive to dif¬ ferential pressure. The differential pressure will be large enough to open the valve when the load placed on the actuator cylinder is reduced or removed. In the system this will occur when the piston reaches the end of its displacement path and the load is removed from the actuator, The flow of the hydraulic fluid into the actuator unit is then at a lower pressure, but at a faster rate. As the propulsion unit at this point is to be tilted out of the water with power to propulsion unit being removed, less force is necessary and the lower hydraulic pressure moving at a higher velocity through to the actuator is sufficient to rapidly move the hydraulic actuator and the propulsion unit through its tilt range out of the water.

When it is desired to move the propulsion unit through its tilt range back into the water and into the trim range, the pump is reversed, displacing the fluid in the hydraulic system in the opposite direction and causing the actuator cylinder to rotate the propulsion unit down¬ wards towards the water and correspondingly displacing the piston within the hydraulic amplifier. As stated above, the displaceable or movable means may be a slidable piston, moving within a cylinder. Movement of the fluid under the force of the pump forces the amplifier piston and actuator piston to be displaced as the actuator forces the propul¬ sion unit in the opposite direction, the movement of the piston within the hydraulic amplifier corresponding -to the movement of the actuator piston and of the propulsion unit.

The hydraulic amplifier includes a limit means which may be removed from an end and placed within the path of movement of the said amplifier piston or may be, but not necessarily at the other extreme end of its dis¬ placement path. When the amplifier piston reaches that limit means, the switch corresponding to the valve is actuated causing the amplifier to be bypassed such th«

fluid from the actuator flows directly through the ampli¬ fier, bypassing the amplifier and through to the pump. The continued operation of the pump then displaces the fluid from the actuator and through the hydraulic amplifi without amplification to further displace the hydraulic cylinder and the propulsion unit down through the balance of its tilt range. Continued operation of the pump force the propulsion unit through the trim range until the extreme of the trim range is reached where further move- ment is prevented.

When during this movement of the propulsion uni in the downward direction, the pump is reversed, the hy¬ draulic pressure in the system will force the amplifier piston to move away from the limit means and in the other direction along its displacement path and towards the one end. At this point, the switch within the amplifier will be actuated connecting the amplifier within the hydraulic circuit, and providing hydraulic fluid with increased pressure but at a slower velocity to the hydraulic cylind actuator.

In the contemplated use of this device, this part of the operation will take place after the system ha been operated in reverse to bring the hydraulic propulsio unit from its full tilt position downward and to a posi- tion where it immersed in the water and where further reversal of the pump and fluid flow will be for the purpo of causing a desired trim.

In a system for providing hydraulic fluid at a first higher pressure to a hydraulic cylinder to move a propulsion unit through a trim range, and at a lower pre¬ ssure but at a faster rate to move the hydraulic cylinder and a propulsion unit through a tilt range, a hydraulic amplifier is provided with means for switching the ampli¬ fier in and out of the hydraulic circuit to produce a change in pressure required for the respective trim and tilt operation.

This invention accomplishes its result by means of a novel arrangement of a switch being a valve mounted the piston within the hydraulic amplifier and dispenses.—

with external switches and control systems to alter the system from a trim to a tilt operation and visa-versa.

Additionally, this system uses a single hydrau¬ lic cylinder for both trim and tilt operations. Use of this single cylinder is made possible by the hydraulic amplifier and its internal valve arrangement. When the propulsion unit and the hydraulic cylinder has moved through a range- corresponding to the trim range, the valve arrangement within the pressure amplifier is switched by differential fluid pressure and fluid at a lower pressure _s provided directly to the actuator but at a faster rate for tilt operation.

The invention is described with reference to its use with a load such as a marine propulsion unit and parti¬ cularly where the propulsion unit is tilted or rotated out of the water and where the unit may also be rotated through a trimming range when immersed in the water.

As is known, a marine propulsion unit, under- drive, exhibits a strong force in one direction, tending to rotate or drive the propulsion unit towards the transom of the boat. Hydraulic systems are most commonly used to displace the propulsion unit forward and backward within a trim range when the propulsion unit is immersed in the water. When underdrive and to displace the propulsion unit away from the transom of the boat, a considerable force must be developed within a hydraulic actuator.

Where the propulsion unit is displaced through its trim range, further rotation or movement of the hydrau¬ lic propulsion unit then tilts the propulsion unit out of the water. For tilt, the drive is removed from the marine propulsion unit and less hydraulic pressure is required for the actuator to rotate or displace the propulsion unit through the balance of its range of movement and particu¬ larly through the tilt range.

With regard to this application and for refer- ence purposes, movement of the propulsion unit from a position where it is closest to the transom of the boat, through its trim range, into and through its tilt range to its other extreme position out of the water, is

movement in a first direction. The first direction then is identified as movement of the propulsion unit through its trim range and its tilt range rotating it in an uppe direction removing the propulsion unit from the water. Accordingly, movement of the propulsion unit i the reverse or second direction would be downward toward the transom of the boat and through its tilt range and i trim position immersing the marine propulsion unit in th water.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS, la through Id show in schematic form, th system in various stages of displacement. FIG..la showi the amplifier system with the piston at its limit means wherein the amplifier is bypassed. FIG. lb showing the piston movable being midway between its limit means and its opposite end position in its displacement path and wherein it provides an amplified pressure to the actuato FIG. lc shows the amplifier piston at its end position a stopped from further movement and wherein the amplifier is bypassed to provide fluid to the actuator at the pump velocity and pump pressure, and FIG. Id shows movement o the piston within the amplifier to its limit means responsive to movement of the actuator from its tilt pos tion with the pump pressure reversed from that shown in FIGS, la through lc.

FIG. 2 shows in cross section, the amplifier assembly with the piston at one end at its stopped posi¬ tion.

FIGS. 2a, 2b and 2c show in cross-section the surfaces of the piston at various positions along its axial length.

FIG. 3 shows in cross-section, a detail of the switch means, being a hydraulic valve within the ampli¬ fier piston.

DESCRIPTION OF THE PREFERRED EMBODIMENT

FIGS, la, lb, lc and Id shows operation of the hydraulic system in a first direction, proceeding throug

the trim range to the tilt, r ^e to, a.full extension of the hydraulic actuator cylinder where the propulsion unit is in its full tilt position.

The hydraulic unit is shown in schematic form and wherein the same numerals indicate the same and simi¬ larly operating parts.

As shown, a hydraulic pump 3 provides fluid to a hydraulic amplifier indicate generally as 5. The hydrau¬ lic amplifier 5 has a first port 7 connected to the pump 3 and a second port 9 connected to the hydraulic actuator cylinder shown as 11. The hydraulic amplifier 5 as is well-known, has a displaceable means piston which may be a piston 13, having a first corss-section area 15 shown in FIG. 2b and a second cross-sectional area 17, shown in FIG. 2c, area 17 being an annular area represented by the difference between the area of face 15 of the piston 13 and the area of face 19 of piston 13, shown in FIG. 2a.

The piston 13 is displaced or moves within the cylinder assembly 21 of the hydraulic amplifier 5 between a first extreme position at the top of the amplifier cylin¬ der 21 shown as position B and a second extreme position shown as position A at the bottom of the amplifier 21.

It being understood that the terms top and bottom are used for reference purposes only and this invention in no way requires that the hydraulic cylinder be aligned as shown in the drawing with respect to top and bottom.

Seals 23 and 28 are provided for allowing move¬ ment of the amplifier piston 13 within the cylinder 21 without loss of fluid and without fluid communication between that volume bound by face 15 of piston 13 and that volume bound by face 17 of piston 13.

The piston 13 is shown as having a switch means 29 which may be a valve assembly as shown having a valve 33 and valve seat 34, a means for closing the valve shown as spring 32 and means for opening the valve shown as plunger 36 positioned to a limit means shown as bottom wall 35 of cylinder 21.

The fluid may be communicated to the actua e. -?-

c under 11 through pert.9 of the cylinder 1 cordu.it 43 and port 45 within the cylinder 11.

Operation in the system is- described assuming that the load 49 is at its fully downwardly extended pos tion with the hydraulic cylinder 11 and the load propuls unit 49, being at ievel C at one end of the trim range.

Assuming now that the pump 3 is operated in a first direction to apply pressure to the system, fluid u pressure is applied to the hydraulic amplifier 5 through port 7 and to that volume adjoining the surface 15 of piston 13.

Although the plunger 31 in* contact with the b tom of the amplifier cylinder 35 as shown in FIG. la, forces the valve 29 to open, communicating the volume of the amplifier cylinder adjoining face 15 of piston 13 to the volume of the cylinder adjoining face 17 of the pist 13 sufficient force is developed due to the differences affected surface area to move the piston 13 up towards position B from the position A shown in FIG la. As shown in FIG. 15, movement of the piston from position A to position A-B between extreme position A ^" and B correspondingly moves the plunger 31 from the bottom 35 of the amplifier allowing the valve 33 to clos under the force of the valve closing means shown as spri 32.

During this time when the amplifier piston 13 moving between end position A and end position B as show in FIG. lb, the valve will be closed under the force of and the area or volume within the amplifier cylinder adjoining face 15 of piston 13 will be isolated from the area adjoining face 17 of piston 13. With the valve 33 closed, movement of the amplifier piston 19 will force fluid from the amplifier cylinder 21 through port 9 to t hydraulic actuator cylinder 11 and displace the hydrauli actuator cylinder from its initial rest position to a ne position D shown as in FIG. lb.

During the time the amplifier piston is movin the pressure within the hydraulic cylinder 5 will be an amplified pressure relative to the pressure of the pump.

As is well-known in ydraulic amplifiers, the pressure at port 9 will be equal to the pump pressure multiplied by the ratio of the surface area of face 15 of piston 13 to the surface area of the annular surface 17 of piston 19. During movement of the piston, the force pro- duced by the differential, pressure between the volume adjoining surface 17 and the volume adjoining surface 15 will be less than the force of the valve closing means 32 within valve assembly 29 and the valve will be maintained closed as shown in FIG. ^" lb. In FIG. lc, the amplifier piston 13 has been moved to one end of its displacement path at position B. When this point is reached, the amplifier is constructed so that further mechanical displacement of the piston 13 is not possible in the direction from A to B. At this point, and assuming power to the propulsion unit is removed the differential pressure between the fluid in the volume bound by face 15 and the volume bound by annular face 17 will force the valve 33 to open against the force of spring 32, permitting communication between that volume bounded by face 15 and the volume bounded by face 17. The further operation of the pump in the first direction, forces fluid from the pump 3 through port 7 of amplifier 5 through the valve assembly 29 and conduit 37, through the volume of the amplifier cylinder 21 adjoining surface 17, through port 9 of amplifier 21, and conduit 43 connecting the amplifier to the hydraulic cylinder 11 at port 45.

When the piston 13 of the hydraulic amplifier is moved to its extreme position B, and the differential pres¬ sure opens valve 33, allowing communication of the fluid through the amplifier 5 without amplification, the fluid is then moved at a lower pressure but at the velocity of the pump further displacing the piston 47 within the hydraulic cylinder 11 from position D to position E as shown in FIG. lc.

As explained above, where the propulsion system shown as load 49 is at its lowest position shown as C in FIG. la, initial displacement, corresponding to the dis¬ placement between A and B of the amplifier piston 12 will

be through the trim range position _e the displacement bei C to D of the piston 47 and the propulsion unit 49.

When the amplifier piston is at position B, an with the valve 33 open as explained above, the pump will connected directly through to the hydraulic, cylinder 41 bypassing the hydraulic amplifier 5. The fluid within t system will be moved at the pump velocity but at the low pump pressure, directly to the hydraulic actuator and wi rapidly move the actuator and the propulsion unit from p ition D to E representing the tilt range. Operation of the device is now shown with refe ence to FIG. Id wherein the propulsion unit 49 shown as position 1 in Phantom at the extreme end of its tilt pos tion, is lowered through its tilt range and its trim ran back to its extreme from position C. As can be seen in FIG. lc, when the pump 3 is stopped or reversed, the differential pressure existing face 15 of the amplifier piston 13 will no longer mainta the valve 33 in valve assembly open, valve 33 will close connecting the hydraulic amplifier 5 in the hydraulic circuit, so the hydraulic amplifier piston 13 is displac downwardly in a second direction from position B towards position A. As the hydraulic amplifier piston 13 moves from position B to A, a corresponding displacement of th actuator piston rod 47 and the propulsion unit 49 from i extreme tilted position E to an intermediate position sh as F will take place corresponding to the movement of th piston within the hydraulic amplifier from B to A.

As explained above at position A, the force of the plunger 36 against the limit means shown as the bott 35 of the cylinder 21 of the amplifier 5 will open the valve 33 allowing communication of the actuator cylinder 11 through port 9, conduit 37, the valve 29 and port 7 o the amplifier 5 through to the pump 3. As the valve wil be open under the force of plunger 36, the amplifier wil be bypassed and switched out of the hydraulic circuit, a the piston 47 of the hydraulic actuator 11 will be moved under the direct force of the pump and with the velocity the pump through to its other extreme bottom and moving

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propulsion unit 49 to position C.

Operation of the pump in the reverse direction with the unit within its tilt range at F for example, and with piston 13 at B will cause displacement of the fluid, moving the piston 47 within the hydraulic actuator cylinder 11 and moving the propulsion unit.

Movement of the pump in the second direction then displaces or rotates the propulsion unit downward towards the water, and continued movement and operation of the pump displaces the propulsion unit 49 to the trim range between positions C and D. When the propulsion unit is located in the trim range, operation of the pump in the first direction will cause movement of the hydraulic ampli¬ fier piston 19 away from the limit means shown as the bot- tom wall 35, removing the force of the opening means shown as plunger 36 from the valve 33 closing the valve under the force of closing means shown as spring 32 and placing the amplifier within the hydraulic circuit. The amplifier then provides an amplified pressure to permit displacement of the load shown as a propulsion unit 49 to effect proper trimming of the propulsion unit.

Operation of the pump in the reverse direction with the unit within its tilt range at F for example, and with piston 13 at B will cause displacement of the fluid, moving the piston 47 within the hydraulic actuator cylinder 11 and the propulsion unit toward position C.

The amplifier piston 13 will also experience cor¬ responding movement until it reaches a limit means where the valve 33 will open allowing direct communication of the hydraulic actuator cylinder 11 with the pump 3 and rapid movement of the piston 47 and the associated propul¬ sion unit 49 at the speed and pressure of the pump 3.

In the described operation of the amplifier 5, valve 33 opens when the piston reaches position A. However, it should be understood that position A is not necessarily at an end or limit of the displacement path of the piston 13 within the amplifier.

. As will be understood by one skilled in the art, a limit means for contacting a means to open valve 33 can

be placed within the hydraulic amplifier 5 to open the valve 33 before the piston 19 reaches position A. For example, a contact means can be placed within the ampli fier 5 which contacts the plunger 36 when the piston as bly is somewhere between position B and A. It should be understood that the limit means shown as bottom wall 35 in this embodiment, may be plac anywhere along the path of the piston 13 between positi A and position B and may be any suitable means which co tacts the actuator means shown as plunger 36 responsive movement of the piston 13 towards the limiting means, a wherein further movement of the piston 13 in the same direction towards the limiting means, forces the actuat means against the valve, opening the valve and allowing communication between the two volumes. Operation of the amplifier is now shown with reference to FIGS. 2 and 3 wherein a detail of the valv assembly 29 is shown.

The valve is mounted in the displaceable pist 13 and includes a means shown as spring 32 forcing valv body 33 against valve seat 34. An actuator means for opening the valve is shown as a plunger 36 having an en 38 protruding below the surface 15 of the piston to eng a limit means such as the bottom wall 35 of cylinder 21

Movement of the amplifier piston 13 towards p tion A places the plunger 36 in contact with the bottom wall 35 of the amplifier cylinder. The plunger 36 then displaces valve body 33 against valve spring 32 opening the valve and permitting fluid to flow from the volume bounded by surface 17 through conduit 37, valve seat 34 valve body 33, through to port 7. A small annular spac may be left between piston 13 and the inner wall of cyl 21 to permit fluid to flow out conduit 37.

It should be noted that it is not necessary f the piston to be displaced to the bottom or to the bott wall 35 of the amplifier cylinder 21 as any suitable me for contacting the plunger 31 and forcing the plunger against the valve body 33 and against the force of the spring 32 opening the valve may be used. For example...

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suitable mechanical structure may be placed close to posi¬ tion A and removed from position B to contact the plunger extension 38 and open the valve before the valve reaches the bottom wall 35 of the cylinder. However, the bottom wall is a convenient place for locating the limit means for the valve and for that reason is shown ^" as such in the preferred embodiment.

Further, it should be known that a plunger is not required as any suitable actuating means may be used, responsive to movement of the piston, to contact the valve, and open the valve. For example, a structure stationarily mounted in the cylinder, and located in the path of the valve so it contacts the valve when -the valve reaches a corresponding limit position, opening the valve and communicating the volume bounded by surface 15 to the volume bounded by surface 17.

As hydraulic fluid is driven in a first direc¬ tion, -the differential force against the surface 15 forces the piston to be displaced towards position B from position A, moving the piston away from bottom wall 35 and allowing the valve to close. The piston is then displaced up until the point where the annular surface 17 contacts the stop 23 located in the cylinder 21. At this point, and assum¬ ing no power is provided to the drive unit, the differen¬ tial pressure on the plunger side of the valve compared to the force of the spring against the valve opens the valve and provides hydraulic fluid under the speed and pressure of the pump to the hydraulic actuating cylinder 11 to dis¬ place the cylinder through its tilt range. When the pump is stopped or reversed, the differential pressure forcing the valve open is removed and spring 32 forces the valve closed.

However, if power is supplied to the propulsion drive unit, the force of the pump by itself will be insuf¬ ficient to displace the hydraulic cylinder against the force of the propulsion unit and the system will go into hydraulic stall or fluid will be ^' directed through a bleed valve.

With the piston of the hydraulic amplifier located

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at position B, operation of the hydraulic pump in the second direction, displaces fluid from the hydraulic cyl der to the amplifier, and to the volume defined by surfa 17 displacing the piston from position B to position A. When the piston reaches the limit means, plunger 36 is forced against the valve body 33, and opens valve and permitting fluid to flow around the valve seat 34, fluid under the speed and pressure of the pump is forced to th hydraulic cylinder allowing the hydraulic cylinder to mo its end position where the hydraulic unit is placed to i fully lowered position in the water corresponding to pos tion C in FIG. 1.

The principles of this invention have been sho with reference to the preferred embodiment, but should n be limited to the description of this embodiment as show For example, the manner of opening the switch means mounted in the movable portion of the amplifier, b driving the movable means to one end of its path may be changed to any other suitable arrangement. One possible arrangement would be to place a limit means in the path the movable means, a limit distance from the end of the path. In this way, the amplifier could have two limit means, neither at the end of the path, or one limit mean which may or may.not be at the end of the path, with the the switch being opened by the third pressure when it is at the respective other end of the path, or the switch m be operated by the fluid under pressure at both ends of path.