AUTOMATIC VARIABLE LEVERAGE MANUAL HYDRAULIC PUMP

Disclosure

This application is a United States Patent Cooperation Treaty (PCT) application claiming the benefit and priority date of provisional application, filed November 16, 2005, United States Serial No. 60/737,163 of the same title which provisional application is incorporated herein by reference.

Brief Description of the Prior Art: It is known to use hydraulics to control the rigging and other controls of a sailboat. Generally such pumps must be manually operated to comply with various sailing rules, and particularly when racing. Such hydraulics necessitates a source of hydraulic pressure. Various attempts have been made to make a manually operable hydraulic pump which changes the amount of effort needed to be applied by the operator. One prior art approach is to vary operative piston size, as by using a stepped piston and complimentary stepped cylinder and utilizing one or the other or both areas of a stepped piston and cylinder.

Summary of the Invention: A manual or lever operated manually hydraulic pump of the present invention for use on large racing and cruising sailboats for driving various hydraulically operated control functions is disclosed. The hydraulic pump of the present invention automatically adjusts the operator's mechanical advantage through the use of various features, such as a control cylinder driven by the system fluid pressure - the pressure imparted against the payload.

In a first embodiment, referred to as PUMP DESIGN 1, the pumping lever consists of a single-acting push cylinder that is energized by direct system pressure or by reduced pressure through an exchange device (ie a differential cylinder). In either case, the extension of the lever is a function of the system pressure such that the higher the pressure, the greater the extension, resulting in greater mechanical advantage to drive the pump.

In the second embodiment, referred to as PUMP DESIGN 2, the lever ratio is adjusted by moving the lever pivot or fulcrum point (cylinder rod attachment point

remains fixed but moves relatively to the lever axis). As in PUMP DESIGN 1, the movement of the pivot point is a function of system pressure. Alternatively this pivot point could be fixed and the attachment point of the lever to the cylinder relatively move to change mechanical advantage. Alternatively both these invention aspects could be combined in a single pump. That is the pump would have a lever that lengthens at higher output pressure and a fulcrum pivot that also increases the mechanical advantage at higher pressures. Further, the present invention can be provided in rotary input pumps using either a lever to rotate a crank and/or a pair of crank handles or pedals, with either the lever or crank charging length to provide increased mechanical advantage.

Brief Description of the Drawings:

Figure 1 is a schematic plan view of a sailboat with a hydraulic system utilizing the hydraulic pump of the present invention; Figure 2 is an enlarged elevational view of the mast and boom of the sailboat of Figure 1;

Figure 3 is a schematic view of the first embodiment Pump Design 1, of the hydraulic pump of the present invention in a low lever length and mechanical advantage position (illustration A); Figure 3 A is an enlarged, schematic cross-sectional view of a circled portion of the lower end lever of the pump of Figure 3;

Figure 4 is a schematic view of pump shown in Figure 3 at maximum pressure with full lever extension in a high mechanical advantage position

(illustration B); Figure 5 is a cross-sectional view of another embodiment pump of the present invention, Pump Design 2 at low fulcrum and low pressure position

(illustration C);

Figure 6 is a view similar to Figure 5 but showing that pump at high pressure, high fulcrum and high mechanical advantage (illustration D); Figure 7 is a perspective view of the present invention, Pump Design 2, and illustrates the linkage for connecting the manual operating lever to the respective dual pistons of the pump;

Figure 8 is a perspective view of the Pump Design 2 of Figure 7 of the present invention, with its lever displaced to one side;

Figure 9 is another embodiment manual hydraulic pump of the present invention with variable mechanical advantage; Figure 10 is an elevational view of the pump of Figure 9 in a low pressure mode;

Figure 11 is an elevational view of the pump of Figure 9 in a high pressure mode; and

Figure 12 is a cross-sectional view of yet another embodiment of a pump of the present invention that features both the elongating lever and changing fulcrum;

Figure 13 is a schematic view of a further embodiment of the pumps of the present invention which is rotated by pivoting the lever; and

Figure 14 is a schematic elevational view of another embodiment pump of the present invention that is rotary operated.

Description of the Preferred Embodiments:

Referring to Figures 1 and 2 is a sailboat 10 having a mast 12 and boom 14, carrying a sail 15, is shown on which the pump 20 (of any of the embodiments disclosed herein) of the present invention could be used. The pump 20 forms part of a hydraulic system 22 to operate certain devices on the sailboat 10. For example, the pump can be used and circulated though a valve manifold 22 with individual valves for example, 24, 25, 26, 27, 28 and 29 connected via hydraulic lines, for example, 30, 31, 32, and 33 to various devices used to adjust the sails or performance of the boat such as fore or back stay tension cylinder 40, port and starboard athwartship adjust cylinders 42 and 44, outhaul cylinder 46 (Fig. 2), and boom vang cylinder 48 (Fig. 2). It should be understood that the devices shown are illustrative, and not by way a limitation, and other devices could be hydraulically operated or controlled by one or more pumps of the present invention, such as for a centerboard adjustment (not shown). Referring to Figures 3, 3A and 4, the first embodiment 60 shows a schematic version of PUMP DESIGN 1. In Figure 3, line 30, could connect to a manifold and actuators, as represented by the arrowhead 31. In this embodiment there are two pumping chambers 61 and 62, connected by linkage 61 A and 62A to the pumping

lever 63. At the bottom of the lever 63 is a lever cylinder 64 (see Fig. 3A). The pressure side of both pumping cylinders or chambers 61 and 62 and the lever cylinder 64 are plumbed common - all three are exposed to the system pressure providing feedback of the pump pressure. The rods or linkage 66 and 68 of the pumping cylinders 61 and 62 pistons are coupled to the pumping lever 63 by the linkage 61A and 62A such that the lever 63 causes them to move relatively up and down alternately as the lever 63 is moved side to side as indicated by the arrows 61C and 62C. This causes each pumping cylinder to draw in fluid as the lever moves in one direction and pump that fluid out into the system from reservoir 6 IF and 62F as the lever moves in the opposite direction. The flow into and out of each cylinder is controlled by two check valves 6 ID and 6 IE and 62D and 62E serving each cylinder, like those shown in Figures 1 and 2 or others. The above describes the industry standard method of pumping action (varying piston area 3). If there were no other provision to change the mechanical advantage of the lever, as the system pressure increased, the operator would find the effort to move or pump the lever back and forth increasingly difficult.

The pump of the present invention automatically compensates by providing an automatic additional increase or change of mechanical advantage by tapping or feedback of the system pressure and using it (the higher pressure for example) to drive the hydraulic cylinder 64 located in the pumping lever 63 which adjusts and increases the mechanical lever length to compensate for the increased pressure. For example, the lever 63 above the fulcrum or pivot point or 63 A could lengthen from 8 inches to say 20 inches (compare Figure 3 to Figure 4) to greatly increase mechanical advantage, perhaps by 2 or 3 times or higher say up to 5 times. The pump could be designed to have a lever with say 25:1 mechanical advantage and with the extended lever length a further 2.5:1 to 1 or greater mechanical advantage. Thus, the pump's overall mechanical advantage of 25:1 to 30:1 (lever unextended) changes or increases to a much higher mechanical advantage of 60:1 to 80:1 (lever extended). In PUMP DESIGN 1, Figures 3, 3A, and 4, the control cylinder 64 that performs the mechanical advantage ratio change is housed inside the lever 63. As noted in the magnified detail as shown in Figure 3A, and the lever comprises a cylinder 68, that has an interior displacing or stand tube 70 and a piston 72 which is

annular in shape. The combination of the interior stand tube 70 and the annular piston 72 create a very small area on which the fluid acts. This allows for a smaller, less forceful spring 74 needed to oppose the piston 72. The spring 74 is attached to the piston 72 predisposing it toward the retracted position at low pressure (see Figure 3). A hose fitting 80 is attached to the cylinder to allow either direct system fluid or fluid from an optional pressure step-down chamber 82 to flow in and out of the lever cylinder 64. It should be noted that the fitting 80 can be mounted anywhere on the cylinder as it has no "dry" side, and it is advantageous to mount it close to the lever pivot 63 A to reduce motion that could cause hose joint strain and possible breaks or leakage. The pressure step-down device 82, such as a differential cylinder if present, reduces the pressure transferred, feedback to the pump lever 63 which allows for a smaller, less forceful spring 74 to be used.

Figures 3 and 3 A show the pump lever handle unextended in the low pressure mode. The fluid pressure is too low to counteract the force of the spring 74 so the lever 63 remains retracted to its lowest or shorter position. In this retracted mode, the operator's hand, gripping the top 63D of the lever 63, is closer to the lever pivot or fulcrum point 63A. This allows the operator to quickly move larger volumes of fluid in a given time as the length of the lever strokes are short relative to the length of the pumping cylinder stroke so that more strokes can be made. This greater fluid displacement moves the system (pressure driven) elements - cylinders, rotary actuators, say 40, 42, 44, etc. (not show) quicker. As system pressure increases, the force of the spring 74 is overcome by the fluid pressure inside the lever cylinder 64 acting on the small area of the piston. This causes the piston to move vertically and, within limits, in infinitely variable fashion as a function of pressure which moves the lever upward and operator's hand farther from the lever pivot or fulcrum (say from 8 inches away to 20 inches away) which increases the mechanical advantage of the lever. At maximum system pressure say 10,000 psi, the lever is at full extension (see Figure 2), and the operator's hand is farthest from the lever pivot point producing maximum mechanical advantage. This lessens the required force to operate the lever, but the decreased flow slows the speed of the actuators operated by the pump. Unlike a conventional manual hydraulic pump of the prior art, which might require a 50 lbs. operator force to reach the 10,000 psi maximum pressure, in the pumps of the present invention, the operator's force would

be reduced and not exceed, say, 30 lbs., but yet be able to achieve quicker operation at lower pressures. Unlike variable stroke pumps, this design of the present invention doesn't change the stroke or displacement in response to system pressure, and it maintains the operator input effort at a relative constant level, regardless of the system output or operating even at high pressure. With this design the lever mechanical advantage could change from between 1 to 3, with changes of 1 to 5 being preferred.

Referring to Figures 4 to 8, as in PUMP DESIGN 1, PUMP DESIGN 2 (100) comprises upper and lower pump bodies 102 and 102A, connected by fastener 102B and achieves pumping through oscillation of the pump lever 104 partially shown in Figure 4 and Figure 5. The pump lever is attached to a set of opposed pistons 106A and B and cylinders 108A and B shown in Figures 4 and 5. The piston 106A and 108A are connected together by a middle connecting section 103 carrying a slidable on the lever 104, spherical bearing 103 A. Each of these pistons and cylinders features a conventional, multi-diameter, or stepped, design. In this design, each piston is actually two different diameter concentric pistons that are sealed from each other and the result is two independent pumping chambers 106C and D and 108C and D on each piston, the chamber 106C and 108C being annular in cross-section. As in PUMP DESIGN 1, a group of valves controls the flow into and out of each diameter piston chambers 106C and D and 108C and D. However, in the larger diameter pumping chamber 106C and 108C, the valve that controls the flow into the piston is variable as a function of system pressure; it can be held open after a certain pressure is reached to maintain a free path to and from the oil reservoir, like 62D and F. Of course, there could be a single reservoir, instead. In this configuration, the fluid is drawn into the larger diameter piston from the fluid reservoir and then pushed back to the reservoir on compression with virtually no effort. This feature allows the output of the larger diameter piston to be negated after the system pressure exceeds a designated point and reduces the amount of force required by the operator when operating the pump in this mode at the expense of reduced pump volume output. The above in this paragraph describes the industry conventional standard method of reducing the effort to drive a pump at higher pressures by stepped piston-stepped cylinder construction.

Similar to PUMP DESIGN 1, PUMP DESIGN 2 also offers automatic adjustment of mechanical advantage as a function or feedback of system pressure. This takes place through the movement of the pivot point 112 of the pump lever 104 that is attached to the pistons 106A and 108A. The movement of the pivot piston 114 and the cylinder 118, motivated by the output hydraulic pressure of the system the pump is supplying, alters the mechanical advantage the operator has over displacing the pistons 106A and 108A. The change in the positions of the pivot point 112 and piston 114 is shown in the different locations in Figures 5 and 6. A spring 118 biases the pivot point piston into its lower, low mechanical advantage position until a certain pressure is exceeded.

With the two-diameter pumping chambers and the automatic variable mechanical advantage of the present invention, PUMP DESIGN 2 offers a two-stage pump with variability of mechanical ratio within limits within each stage.

Referring to Figure 9, another embodiment pump 200 is shown. This pump has two opposed pumping chambers or cylinders 202 and 204, carried by a frame 206. The pump 200 also carries a lever 208. Moving the lever 208 back and forth as indicated by the arrow 210 causes a pumping action through inlets and outlets 202A (fluid intake from hydraulic tank) and 202B (pumped fluid pressure) and 204A (fluid intake from hydraulic tank) and 204B (pumped fluid pressure), respectively. There are check valves in these input and output paths to provide one way flow from the reservoir through the pump to the actuated device. While not shown, all actuated devices, such as those shown in Figures 1 and 2, provide a return from the respective device back to the reservoir when pressure in the device is lowered or released. If there were no provision to change the mechanical advantage of the lever, as the system pressure increased, the operator would find the effort to pump the lever increasingly more difficult. This pump automatically compensates by tapping the system pressure and using it to drive a hydraulic cylinder which adjusts the mechanical lever ratio such that the pumping effort is relatively constant. hi PUMP DESIGN 3, the control cylinder 214 that performs the mechanical advantage ratio change is housed inside and at the bottom of the lever 208. The clevis 212 of the control cylinder rod 214 is pinned to both yokes 216 on the end of each pumping cylinder rod. Figure 10 shows the pump 200 in the low pressure

mode. The retraction motion of the control cylinder is opposed by a spring (not shown) such that when system pressure is low, the spring forces the control cylinder rod into extension which moves the yokes away from the pumping lever pivot point 220 mounted on the frame 206. This allows for moving more fluid to the system quickly because the greater distance of the pumping cylinder rod ends from the lever pivot cause the pumping pistons to move faster and stroke farther. As the system pressure builds in Figure 11, the control cylinder rod, in variable fashion between limits, is forced to retract against the spring force which draws the pumping cylinder yokes closer to the lever pivot point 220. Compare Figure 10 to Figure 11. This change lessens the required force to operate the lever 208 because the mechanical advantage has been increased, but slows the speed of the pumping cylinders and reduces their stroke and volume output. Unlike variable stroke pumps, this design doesn't just change the stroke or displacement in response to system pressure, it also maintains the operator input effort at a relative constant regardless of the system pressure.

Referring to Figure 12 (combination of two pump concepts - adjusting lever length and adjusting lever pivot), a pump 300 of the present invention is shown which combines the mechanical advantage increasing features of an increasing lever length dependent on (increasing) system pressure and a decreasing fulcrum length (lever pivot adjusts dependent on system pressure). As system pressure goes up lever length would increase, and the pivot point would also shift to provide more mechanical advantage. As is shown, the pump 300 has a lengthening lever 304 which increases in length with higher pressure due to a lever increasing length cylinder 306 inside the lever 304, like that shown in Figures 3-4 and the fulcrum or pivot change feature 308, like that shown in Figures 5 and 6. The lever 304 can move back and forth as shown by the arrow 310 to cause the pumping action.

Figure 13 shows another embodiment pump 400 of the present invention that has a pivoting lever 402 with a pivot point 403 which can increase its length as indicated by the arrow 404. This version has a variable mechapical advantage pump with reciprocating input (indicated by 410) lever 409 converted to rotary motion. The rotary motion (indicated by arrow 409) is of a "cam" 412 which can drive a cam follower 414 causing reciprocation of a pumping piston 416 (indicated by the arrow 419) to pump fluid. The lever length changes with pressure changes, becoming

larger as pressure increases. Appropriate valving would be needed as known to persons skilled in the art and indicated by the input 4161 and output 416O. The lever 402 is connected by a rod 406 to a crank or cam 408 which can be rotatably driven about a center 409 as indicated by the arrow 407 in a circle by pivoting the lever 402 back and forth, as indicated by the arrow 410. The outer or cam surface 412 cause a cam follower 414 to oscillate a piston 416 in a cylinder 418 against, say a spring (not shown) to cause a pumping action and pressure at output 420.

Referring to Figure 14 (variable mechanical advantage pump - changing rotary crank length), a pump rotary form of increasing mechanical advantage pump 500 is shown, this pump has a rotary crank 502 and hand or pedal portions 504 which can be rotated by the operator about a center 506 as shown by the arrow 508. To provide the mechanical advantage changes in the crank length indicated by arrows 501 can be made by providing crank lengthening cylinders 510, similar to the fulcrum or handle lengthening cylinders previously described. As the system pressure in cylinder 518 increases the crank lengths can increase. The outer surface of the crank includes a cam surface 512 which drives a follower 514 to move a piston 516 relatively up and down on the cylinder 518 to increase the pump pressure through an outlet 520. As before, the output pressure is provided or carried to the cylinder 510 to increase the crank length at high pressure. While several embodiments of manual pump with automatically increasing mechanical advantage has been disclosed and described, it should be understood that equivalent elements and equivalent steps of those disclosed would still fall within the scope of the invention in the following claims.