WO2006042124A1 - Multi-cylinder reciprocating uniflow engine - Google Patents

Abstract

In a multi-cylinder, single crankshaft, reciprocating piston engine with at least three cylinders distributed along a common crankshaft to provide a rotational output upon provision thereto of a supply of an expandable working fluid at a predetermined initial condition, a movable inlet valve is provided at each cylinder. An inlet valve closing mechanism includes a pressure responsive element coupled to a stem of the inlet valve and responsive at least to a pressure of the cylinder near or at TDC for driving the inlet valve to a closed position thereof under action of the pressure, and a control element for adjusting at least one of a closing timing and a closing speed of the inlet valve being imparted by the pressure responsive element.

Description

MULTI-CYLINDER RECIPROCATING UNIFLOW ENGINE

[0001] The present Application for Patent claims priority to Provisional Application No. 60/616,839 filed October 8, 2004 the entirety of which is expressly incorporated by reference herein.

[0002] The entireties of related U.S. Patents No. 4,698,973, 4,938,117, 4,947,731, 5,806,403, 6,505,538 and Provisional Application No. 60/506,141 are also incorporated herein by reference.

BACKGROUND

[0003] The described embodiments relate to a multi-cylinder reciprocating uniflow engine.

[0004] There are many circumstances where rotary mechanical power from a totally self- contained unit is highly desirable, e.g., to power an artesian pump in a remote desert location where the only source of energy is the sun. Other applications include, but are not limited to, recouping waste heat from factory chimneys, from auto engines, from exhaust of many kinds etc. The engine should operate over a long period of time without the need for any external source of electricity or manual inputs to restart it after a stop or to control its operation between stops. U.S. Patent No. 6,505,538 discloses such an engine.

[0005] FIGs. 1A-1B correspond to FIGs. 21-20 of U.S. Patent No. 6,505,538, respectively. As discussed in U.S. Patent No. 6,505,538, the closing rate of the inlet valve 88' is a function of the combined force being applied by the two small pneumatic pistons 62, 620 on the closing mechanism. These forces are linearly or directly proportional to the varying TDC (top dead center) pressure and BDC pressure of the working chamber, i.e., the change in the acting force (affecting the closing speed of the inlet valve 88') is directly proportional to the change in pressure occurring in the working chamber 58. The BDC pressure is the residual pressure collected in the storage chamber 218 which, in turn, is respectively acting on the small pistons 62 within this chamber to fine tune the closing rate during normal operation. According to the disclosure of patent U.S. Patent No. 6,505,538, if the residual pressure at the end of the working piston stroke is higher or lower than a desired value, the mechanism will adjust so as to close the inlet valve 88' faster or slower, respectively, thus optimizing the engine efficiency.

[0006] The force F caused by the TDC and BDC pressures acting on the two small pneumatic pistons 62, 620 of the mechanism is equal to the area A of the piston surface times the pressure P acting on that surface, or F = A*P. Since the surface area A of the pistons acting on the closing mechanism must be a fixed size, the force F is always directly proportional to the varying pressures at TDC and BDC and is linearly predictable.

[0007] However, the force required to close the inlet valve mechanism is not linear or directly proportional to the forces actually available in the working chamber 58 and residual pressure chamber 218. Force F of the mechanism is equal to the mass m times the acceleration a (where m is the effective mass of the closing mechanism and a is the acceleration required to close the mechanism at a predetermined rate to achieve the desired expansion ration for optimum efficiency). Since acceleration a is determined by the following formula: x = l/2at² (where x is the distance traveled by the mechanism and t is the time it takes for the mechanism to travel the distance x to close the valve and since the distance x is fixed, the acceleration a, according to the above formula, will be inversely proportional to the square of the time required to close the mechanism, i.e., a =2x/t². In other words, to close the mechanism, with F = ma, the force F required must be 2 times mass m times the distance traveled x divided by the square of the time t², or F = 2mx/t². The force F is inversely proportional to the square of the time t required to close the mechanism. In other words, the more time available to close the mechanism, the less force is required, but this relationship is a parabolic curve and not a straight line proportional relationship. The force F must increase proportional to the square of the decrease in available time t, i.e., to 1/t² or the square root of t. Let 2mx = constant K, therefore, F = K* Vt (equal to K times square root of t).

[0008] Since the force F required to close the mechanism is proportional to the square root of the time t that is allowed for that closing and because the actual available force is the pressure P_TDC and in the residual pressure P_BD_C in the chamber are in a straight line relationship rather than parabolic, the parabolic relationship is desirably established in designing the mechanism. SUMMARY

[0009] In a multi-cylinder, single crankshaft, reciprocating piston engine with at least three cylinders distributed along a common crankshaft to provide a rotational output upon provision thereto of a supply of an expandable working fluid at a predetermined initial condition, an inlet valve closing mechanism is provided for closing a movable inlet valve at each cylinder, the inlet valve having an open position to start the inflow of working fluid into the cylinder and a closed position to stop the inflow of the working fluid into the cylinder, said inlet valve closing mechanism comprising a pressure responsive element coupled to a stem of said inlet valve and responsive at least to a pressure of the cylinder near or at TDC for driving the inlet valve to a closed position thereof under action of said pressure; and a control element for adjusting at least one of a closing timing and a closing speed of said inlet valve being imparted by said pressure responsive element.

[0010] A multi-cylinder, single crankshaft, reciprocating piston engine has at least three cylinders distributed along a common crankshaft to provide a rotational output upon provision thereto of a supply of an expandable working fluid at a predetermined initial condition, said engine further comprising an inlet valve closing mechanism for closing a movable inlet valve at each cylinder, the inlet valve having an open position to start the inflow of working fluid into the cylinder and a closed position to stop the inflow of the working fluid into the cylinder; said inlet valve closing mechanism comprising: a pressure responsive element coupled to a stem of said inlet valve and responsive at least to a pressure of the cylinder near or at TDC for driving the inlet valve to a closed position thereof under action of said pressure; and a control element for adjusting at least one of a closing timing and a closing speed of said inlet valve being imparted by said pressure responsive element.

[0011] A multi-cylinder, single crankshaft, reciprocating piston engine having multiple cylinders distributed along a common crankshaft, to provide a rotational output upon provision thereto of a supply of an expandable working fluid at a predetermined initial condition, said engine further comprising pressure detecting elements arranged to collect data related to pressures at or near TDC and BDC in each cylinder; a mechanism for closing an inlet valve at each cylinder, the inlet valve having an open position to start the inflow of working fluid into the cylinder and a closed position to stop the inflow of the working fluid into the cylinder; and an electronic control element coupled to said pressure detecting elements to receive said data, said electronic control element being further coupled to said mechanism and configured to cause said mechanism to close the inlet valve, at a closing rate or timing determined by said controller based on the received data, using at least one of the pressures at or near TDC and BDC of the cylinder.

[0012] Additional aspects and advantages of the disclosed embodiments are set forth in part in the description which follows, and in part are obvious from the description, or may be learned by practice of the disclosed embodiments. The aspects and advantages of the disclosed embodiments may also be realized and attained by the means of the instrumentalities and combinations particularly pointed out in the appended claims.

BRIEF DESCRIPTION OF THE DRAWINGS

[0013] The described embodiments are illustrated by way of example, and not by limitation, in the figures of the accompanying drawings, wherein elements having the same reference numeral designations represent like elements throughout, and wherein elements having the same reference numeral designations used in U.S. Patent No. 6,505,538 represent like elements unless otherwise stated.

[0014] FIGs. IA and IB are views corresponding to FIGs. 21-20 of U.S. Patent No. 6,505,538.

[0015] Figs. 2-3 are respectively partial cross sectional and partial perspective views of an engine in accordance with an embodiment.

[0016] FIG. 4 is an enlarged cross sectional view showing partially a governor for use with an engine in accordance with a further embodiment.

[0017] FIG. 5 is a partial cross sectional view of an engine in accordance with a further embodiment.

[0018] FIG. 6 is a partial perspective view of the engine of FIG. 5.

[0019] FIGs. 7-9 are enlarged perspective views of engine the engine of FIG. 5 showing various positions of a moveable pivot point.

[0020] FIGs. 10-12 are further enlarged views corresponding to FIGs. 7-9, respectively.

[0021] FIGs. 13-22 are cross sectional views showing the engine of FIG. 5 in operation. [0022] FIGs. 23-62 are cross sectional views showing engines in accordance with various embodiments in operation.

[0023] FIG. 63 is a schematic cross sectional view showing an engine in accordance with a further embodiment.

DETAILED DESCRIPTION

[0024] In the following detailed description, for purposes of explanation, numerous specific details are set forth in order to provide a thorough understanding of the embodiments. It will be apparent, however, that the embodiments may be practiced without these specific details. In other instances, well-known structures and devices are schematically shown in order to simplify the drawing.

[0025] FIGs. 2-3 are respectively a partial cross sectional view and a partial perspective view of an engine 300 in accordance with an embodiment. FIG. 4 is an enlarged view similar to FIG. 20 of U.S. Patent No. 6,505,538 and showing a mode-changing governor which can be used with the engine 300.

[0026] This embodiment addresses the varying closing timing rate of the inlet valve mechanism of multi-cylinder self-starting uniflow engine 300 so as to meet optimum efficiency conditions. The desired closing rate will allow for an optimum expansion ratio in the working chamber 58 at the varying temperature/pressure conditions to achieve optimum engine efficiency. This embodiment also addresses replacing sliding pin 116 (FIG. IA) with a counter pressure spring 391 (FIGs. 2-3) that will overwhelm and thus effectively lock the action of the small pneumatic piston 620 while in the start up mode and release piston 620 in the running mode.

[0027] Specifically, this embodiment adjusts the force acting on the inlet valve mechanism so as to balance pressures P_TDC and P_BDC SO that combined all will conform to the F = K*Vt requirement that will act on the inlet valve mechanism, m other words, this embodiment transfers the linear action of pressures PT_DC and P_BD_C to a parabolic action required to operate the inlet valve mechanism to achieve the optimum expansion conditions in the working chamber 58. [0028] This balance is achieved by designing into the valve closing mechanism a counter spring action which will insure that the action conforms to the F = K* Vt requirement. In operation, when the temperature/pressure is at its lowest usable level, the counter spring 391 will counter the excessive forces PTD_C and P_BDC acting on the small pneumatic pistons 62, 620. This spring action will be gradually neutralized as the temperature/pressure in the working chamber 58 rises to the higher level adjusting the expansion ratio of the working fluid so as to achieve the optimum expansion conditions and thus optimum efficiency of the engine 300. At the highest temperature/pressure condition, the counter spring 391 will be rendered completely or mostly inactive, i.e., in this condition the two small pistons 62, 620 of the closing mechanism will be in full use. hi other words, in the maximum temperature/pressure condition, the forces P_TDC and P_BDC will be essentially the only forces acting on the inlet valve mechanism to close the inlet valve 88', i.e., in this condition, there is substantially no resistant force caused by the counter spring 391.

[0029] Of course, the operating fluid used to drive the engine 300 will determine the temperature/pressure range allowed to start up and run the engine. In a specific embodiment, R-123 is the working fluid, the critical temperature is about 363⁰F, the maximum working temperature is about 35O⁰F, and the minimum working temperature for practical purposes is about 275⁰F. This means that the engine 300 will not start up until the boiler temperature reaches the minimum 275⁰F. When the boiler does reach this 275⁰F parameter, the engine 300 will, of course, be at a high enough temperature/pressure to run in the expansion mode. The engine 300 will turn over in the startup mode as disclosed in the earlier disclosures, such as U.S. Patent No. 6,505,538. However, this embodiment is different from the previous disclosures in that pin 116 (FIG. IA), which is disclosed in U.S. Patent No. 6,505,538 to hold down and lock the operation of small pneumatic piston 620 in the start up mode until the crank shaft developed sufficient rotational inertia or momentum to carry forward the motion between strokes in the running mode, is replaced by the force of the counter spring 391. The counter spring force is greater than the working fluid pressure acting on the small pneumatic piston 620 in the working chamber 58. As disclosed in patent U.S. Patent No. 6,505,538, when sufficient rotational momentum is achieved, piston 620 and seesaw level 625 are unlocked, allowing the tandem action between pistons 620 and 62 (in the running mode) to begin. However, in this embodiment, in the start up mode, the force of the counter spring 391 (instead of pin 116) overwhelms the pressure on piston 620. [0030] In the running mode, at a given temperature/pressure, the counter spring 391 will maintain a predetermined force against the seesaw lever 625 and piston 620. In the running mode, this counter spring force will be less than the force of pressure P_TDC acting on the face of piston 620, so that the differential pressure ΔP plus the pressure acting on piston 62 will equal the force F required to close the inlet valve 88' at the predetermined speed so that the injected working fluid can achieve its optimum expansion ratio. It is estimated that, in the embodiment using R- 123 as the working fluid, the expansion ratio at the optimum condition at 35O⁰F will be about 1:7; at 325⁰F about 1:6, at 300⁰F about 1:5.5; and at 275⁰F about 1:5. Li an embodiment, Helium with the working temperature of about 212⁰F is used as the working fluid. Other, suitable expandable fluids and/or working temperatures are not excluded.

[0031] Regarding the operation of the governor and mode changing means of the engine, the configurations disclosed in patent U.S. Patent No. 6,505,538 can be used in this embodiment. As disclosed in U.S. Patent No. 6,505,538, the governor/mode means will shift the engine 300 from the "start up" mode, which will be in a non-expanding working fluid condition to the "running" mode, which is the more efficient expanding condition in the working chamber 58. The operation is substantially similar to that disclosed in U.S. Patent No. 6,505,538. However, to shift modes, instead of using sliding pin 116 (FIG. IA) to actuate the mode change, this embodiment uses the force of the counter spring 391 to overwhelm the force acting on small pneumatic piston 620 actuated by P_TD_C- Instead of a force being transferred through the sliding pin 116, the force of the counter spring 391 acting on piston 620 maintains the mechanism in the start up mode. The pulling action of the governor, via elongated element 393 which can be a cable or a rod, releases the tension of the counter spring 391, thus freeing the seesaw lever 625 and small piston 620 to work in tandem with small piston 62 to close the main inlet valve 88' in the running mode. Once the governor has shifted from the "start up" to the "running" mode, the mechanism permits the gradual release of the force of the counter spring 391 acting against the tandem action of the two small pistons 62, 620 and accompanying seesaw lever 625 as the temperature/pressure rise and approach the optimum efficiency condition.

[0032] In a further embodiment, the mechanism further includes a second spring 392 which is stronger than counter spring 391 and is used to vary the position, and thus tension of the counter spring 391, as it shifts from the locked position on piston 620 in the start up mode and to the lessening force as the engine 300 approaches the optimum 35O⁰F condition in the running mode. The larger spring 392 is compressed by the pulling action of the governor at the varying RPMs of the engine 300. As this stronger spring 392 compresses, the lighter spring 391 acting on piston 620 and the seesaw lever 625) is pulled away from the piston 620 and seesaw lever 625, releasing its force so that the effect of its counter pressure will be less and less. When the engine 300 reaches the highest desired RPMs, i.e., when the engine 300 reaches its optimum running condition at 35O⁰F, the tension of counter spring 391, acting against the piston 620 and seesaw lever 625, will be substantially zero. The accompanying counter force of this counter spring 391 will create the parabolic relationship necessary to conform to the F = K*Vt requirement so that the closing mechanism will achieve maximum engine efficiency, i.e., the closing of the inlet valve 88' will be timed so as to cause the maximum expansion of the working fluid at the varying temperature/pressure levels.

[0033] The larger internal spring 392 will replace the governor counter spring (604, FIG. IB) of U.S. Patent No. 6,505,538. In this embodiment, built into the governor device is a mechanical blocking device 495 (FIG. 4) which will release of the blocked rotational momentum of the governor once sufficient RPMs have been built up. This insures that the mode change from "start up" to "running" is instantaneous and decisive. For example, the support 218 (FIG. IB) used in the governor mechanism and sliding on frame 210 (FIG. IB) can be blocked by a ball bearing 495 that is loaded with spring 496 and releases with sufficient start up RPMs.

[0034] A further embodiment concerns the configuration of the residual P_TDC chamber 394 which is the start up and fine tuning device. The residual chamber 394 is where the residual BDC pressure PB_DC at the end of the piston stroke is stored and used to fine tune the closing rate of the inlet valve 88' to maximize the expansion ratio efficiency and hence the engine efficiency. If P_BDC is too high, the higher residual pressure will act on small pneumatic piston 62 to close the inlet valve 88' more rapidly. If P_BDC is too low, the lower residual pressure will act with less force in the closing of the inlet valve 88'. This fine tuning means of the engine acts apart from the parabolic relationship discussed in the above embodiments.

[0035] This embodiment improves the residual chamber 394 by moving its access 112 closer to the P_BDC pressure in the working chamber 58 of the engine. The residual chamber 394 is configured so that the vapor pressure from the working chamber 58 can more easily be built up in the residual chamber 394. The check valve 395 between the working chamber 58 and the residual chamber 394 is located very near to the working chamber 58. Compare with the position of check valve 638 in FIG. IA. The check valve 395 works as disclosed in U.S. Patent No. 6,505,538 except that the check valve 395 is connected to a rigid ring plate 396 between the small counter spring 391 and the large spring 392 which replaces sliding pin 116 of U.S. Patent No. 6,505,538.

[0036] FIG. 5 is a partial cross sectional view of an engine 500 in accordance with a further embodiment. FIG. 6 is a partial perspective view of engine 500. FIGs. 7-9 are enlarged perspective views of engine 500 showing various positions of pivot point 800 of rocker lever arm 625. FIGs. 10-12 are further enlarged views corresponding to FIGs. 7-9, respectively.

[0037] In the embodiments disclosed with respect to FIGs. 2-4, co-aligning the straight line relationship of the pneumatic force changes (of the thermodynamic changes in force occurring in the working chamber) counteracted by the parabolic changes in kinetic force of the inlet valve closing mechanism (88', 62, 625 and 620 in FIGs. IA, 2 and 3) is solved by using a counter-spring 391 which balances the excessive force acting on small pistons 620 and 62 at lower pressure levels. As the pressure in the working chamber 58 rises, the counter-spring pressure 391 is alleviated by the pulling action of the centrifical governor (partially shown in FIG. 4) attached to the main drive shaft, i.e., hence the force caused by the counter-spring 391 is eliminated as the engine gains speed.

[0038] The following embodiments utilize another mechanism to regulate, additionally or alternatively, the balance of forces between the linear pneumatic force acting on the small piston 620 and 62 which act against the parabolic kinetic counter-force caused by the inertia of the mechanism. This mechanism utilizes a more effective means of balancing the parabolic/linear relationships by regulating the closing rate as a direct function of the available pressure acting on the engine downstroke. This is done by incorporating a regulator right in the middle of the valve train mechanism. In particular, the fulcrum length of the two lever sides of the rocker seesaw lever arm 625 is changed to adjust for with the changes in the pressure in the working chamber 58, hence, adjusting the closing speed of inlet valve 88' to accommodate the changes occurring in the engine speed. The fulcrum axis is shifted up and down to balance the relationship between the pneumatic forces and the kinetic counter forces of the inertia of the mechanism. [0039] As disclosed in U.S. Patent No. 6,505,538, the inlet valve closing mechanism has a duel function (1) to provide a mode changing means as the engine shifts from the startup to the running mode, and (2) to fine-tune the closing rate of the inlet valve, hi the embodiments disclosed above with respect to FIGs. 2-4, a counter-spring 391 is added to balance the forces between the straight-line relationship of the pneumatic forces and the parabolic relationship of the kinetic force of the inlet valve train mechanism to accommodate for the changing pressure conditions and hence the changing speed of the engine. The action of the small piston 620 is blocked by the rod action that is connected to a mode changing governor (partially shown in FIG. 4).

[0040] In engine 500, the mode changing means remains the same as disclosed in U.S. Patent No. 6,505,538. The rod 116 that is connected to the mode changing governor continues to block the action of the small piston 620 until the engine gains sufficient inertia to insure an overlapping of the down stroke actions of the main pistons of the engine.

[0041] At startup, the engine 500 in this embodiment will begin to rotate in the startup mode and, when sufficient rotational inertia of the engine is gained, the action of the governor will shift the mechanism into its running mode, hi the running mode, two means will take effect that will adjust the closing rate of the inlet valve 88' to the main working chamber 58: (1) the accumulated residual BDC pressure PB_DC that is stored in the storage chamber (e.g., 218 in FIG. IA) of the mechanism acting on small piston 62 and (2) the varying position of the fulcrum 800 (FIG. 5) of the rocker seesaw lever arm 625 with respect to the rods of small pistons 620 and 62. Whereas the first means accounts for any excessive residual waste at the end of the main piston stroke at BDC, the second means addresses the balancing of the pneumatic and kinetic inertia forces of the valve train mechanism action.

[0042] More specifically, in the startup mode, it is essential to maintain the inlet valve 88' (FIG. IA) remain open throughout the down stroke of the drive piston 30a' (FIG. IA) until journal of the sequential driving cylinder piston overlaps into the rotational action. To maintain the inlet valve 88' open throughout the downstroke, the small piston 620 which is at TDC is locked into position. As disclosed in U.S. Patent No. 6,505,538, in the startup mode, the inlet valve 88' is closed by the action of the small piston 62 located in the residual chamber 218. This happens as the main piston 30a', approaching near bottom dead center (BDC), passes the overlap point of the sequential downstroke. When the access point 112 (FIG. IA) is exposed, pressure P_BDC from the working chamber 58 causes the small piston 62 to force the inlet valve plate to slide laterally, closing the main inlet valve 88' to the working chamber 58.

[0043] When the rotational momentum is sufficient to insure that rotation will continue from cylinder to sequential cylinder in the expanded working fluid mode (the running mode), the engine shifts to the "running mode." Once the engine has shifted into the running mode, the small piston 62 accessed to the residual chamber 218 will act to fine-tune the closing rate of the main inlet valve 88'. Small piston 620 and small piston 62 will act in tandem through the exchange action of the rocker lever 625 to create this tandem action.

[0044] It should be noted that the mass weight of the inlet valve 88' and its accompanying small piston 62 is considerably greater than the mass weight of the small piston apparatus 620 which is accessed to the main working chamber 58. The regulator in the middle of the valve train mechanism of engine 500 features a slidable pivot point 800 which is the axis for the rocker lever arm 625. An up and down movement of the axis of the rocker lever 625 determines the two relative fulcrum lengths that are acting on the contact points of the two flanking sliding rods of the two small pistons 620 and 62 of the inlet valve closing mechanism. When the engine 500 is operating at a lower pneumatic pressure, the axis point 800 moves downward to a lower position (FIGs. 7 and 10) which shortens the fulcrum length of the lever of small piston 620 while lengthening the upper leverage to the contact point of the sliding rod of the small piston 62 which acts directly on inlet valve 88'. In this lower axis position (i.e., when the pivot axis point 800 is down as shown in FIGs. 7 and 10), the torque action against the inlet valve 88' is greatly accentuated, slowing down the shutter speed of the inlet valve, accommodating for the excessive pneumatic pressure that is available in the working chamber 58 to act on valve 620. When higher pressures are in the working chamber 58, the pivot axis point 800 is lifted to the high position (FIGs. 9 and 12) and the opposite occurs, i.e., the leverage favors a rapid closing of the inlet valve 88', accommodated for the need for a rapid shutter speed of the inlet valve 88'.

[0045] In engine 500, the pivot point 800 of the lever 625 is a direct function of the pressure levels of the working fluid in the working chamber 58, and hence, incorporates a pressure regulator which is accessed to the pressure of the boiler (upper) side of the inlet valve 88'. The pressure acting on the pressure regulator adjusts the location of the pivot point 800 of the rocker lever 625 to the appropriate position thus insuring that the shutter speed of the inlet valve 88' will meet optimum conditions to achieve optimum engine efficiency. [0046] A further embodiment utilizes the action of the blocking rod 116 (FIG. IA) to regulate the position of the pivot point 800 (the axis of the lever 625). Rod 116 which is attached to the centrifical governor which is responsive to the RPMs of the engine is attached to a laterally sliding wedging means which wedges up and down the bracket housing that houses the pivot point 800 (the axis of the lever 625). This means uses the continued outward action of rod 116 to adjust the position of the pivot point 800. It is attached to the governor and therefore responsive to the RPMs of the engine. However, this same means can be used in tandem with a pressure regulator located in a more remote position or to a temperature regulator or other means of measuring the engines level of performance.

[0047] FIGs. 13-22 are cross sectional views showing engine 500 in operation.

[0048] In engine 500, a pressure regulator 900 is constantly accessed to the pressure available from the boiler. The position of the diaphragm 910 (FIG. 13) in the pressure regulator is attached to the up/down slidable action of bracket 810 of rocker arm 625. Bracket 810 has, in an embodiment, the shape of a horseshoe as best seen in FIGs. 10-12. The up/down action of the pressure regulator diaphragm 910 adjusts the location of the pivot point (the axis point) 800 of the rocker lever arm 625. In other words, this pivot point 800 is attached to slidable bracket 810 which moves with the movement of diaphragm 910 during operation of the pressure regulator 900. The pivot point 800 moves up as the boiler pressure increases and down when the boiler pressure decreases.

[0049] Step 1 (FIG. 13)

[0050] The uniflow engine 500 is in its startup mode with blocker mechanism (or rod) 116 locked into position. Because the engine 500 is without rotational movement, the centrifical governor is in its closed position. In the start up position, at least one of the inlet valves 88' of the three working chambers 58 in the three corresponding cylinders of the engine 500 is open to the boiler pressure once that pressure is released to the engine 500. FIG. 13 shows inlet valve 88' in the open position. As stated, small piston 620 is locked out of operation while check valve 108 is held open, accessing the small piston 62 of the residual chamber 218 to the pressure in the working chamber 58 of the working cylinder in the "Startup Mode." In FIG. 13, the boiler pressure is acting on diaphragm 910 from one side and biasing spring 595 is acting on diaphragm 910 from the other side. The position of diaphragm 910 in FIG. 13 indicates the acting pressure is at a lower working level. As a result, the slidable rocker arm bracket 810 is at the lower position best seen in FIGs. 7 and 10.

[0051] Step 2 (FIG. 14)

[0052] In FIG. 14, the major change, compared to FIG. 13, is that the main piston 30a' of the working chamber 58 in the working cylinder has moved down, uncovering access port 112. This accessing allows the pressure in the working chamber 58 to enter the residual chamber 218 so as to act on small piston 62. Inlet valve 88' is still open until the very end of Step 2.

[0053] Step 3 (FIG. 15)

[0054] Between Step 2 and Step 3, inlet valve 88' is closed by the accessed pressure of the working chamber 58 acting on small piston 62. In an embodiment, the residual chamber 218 is as small as allowable to insure rapid pneumatic action from the pressure in the residual chamber 218 to small piston 62. Because the residual chamber 218 also serves to store the residual pressure at the end of the downstroke, i.e., P_BDC, the residual chamber 218 must have some volume sufficient for expansion action on small piston 62 in the "Running Mode." FIG. 15 shows the closed inlet valve 88' and the exposure, through the complete downstroke of the working piston 30a', of the exhaust ports 512 of the uniflow engine 500. It should be noted that the RPMs of the engine 500 during startup will be very low, and requires only sufficient rotational inertia to insure the continued running when the engine 500 shifts into the more efficient "Running Mode."

[0055] Step 4 (FIG. 16)

[0056] The engine is still in the "Startup Mode." The inlet valve 88' is still closed. The only change in FIG. 16 compared to FIG. 15 is the working piston 30a' has come up to contact with the slidable wedges 593 of the inlet valve 88' in the opening mechanism. In an embodiment, there is no abrasive contact between the working piston 30a' and the wedges 593 of inlet valve 88'; the action is smooth.

[0057] Step 5 (FIG. 17)

[0058] FIG. 17 shows the opening action of the inlet valve 88' with the continued upward movement of the working piston 30a' to the top dead center (TDC). All other components remain substantially the same as shown in FIG. 16. When the inlet valve 88' is open, the boiler pressure rapidly enters the working chamber 58 as shown by arrows Z. The efficiency of the engine 500 is a function of the amount of working fluid allowed into the working chamber 58 before the inlet valve 88' closes, hi an embodiment, it is estimated that at the higher pressure levels, the most efficient expansion ratio would be 1 :7. At the lower working levels, so that the engine 500 can continue to operate, it is expected that the expansion ratio will be closer to 1:5. The disclosed embodiment is arranged to regulate the quantity of expandable working fluid in the working chamber 58 to maximize the overall engine efficiency. The engine 500 automatically uses the conditions of the working fluid, at the near boiler pressure as the working fluid enters the working chamber 58 and at the near end of the down stroke, to determine if the engine 500 has maximized its expansion during the down stroke of the working piston 30a'. In the "Running Mode," the vapor pressure at the near end of the down stroke is stored in the residual chamber 218 to boost or retard the closing speed of the inlet valve 88'.

[0059] Step 6 (FIG. 18)

[0060] FIG. 18 features the mode change from the "Startup Mode" to the "Running Mode" through the releasing slidable action of blocker arm 116 which is acted on by the centrifical governor attached to the main drive shaft. With this action of blocker arm 116, bracket 630 moves out allowing the check valve ball 108 to lower so the check valve can retain the residual pressure collected through port 112 from the expanded pressure of the working chamber 58 at near bottom dead center (BDC). In FIG. 18, the only changes, compared to FIG. 17, are the sliding action of the blocker arm 116, the closing of the check valve 108, and the continued down stroke of the working piston 30a'. At this point the engine 500 has shifted into the "Running mode." The slidable rocker arm bracket 810 is still at the lowest position as shown in FIGs. 7 and 10.

[0061] Step 7 (FIG. 19)

[0062] FIG. 19 shows the engine 500 in the "Running Mode." The upward movement of diaphragm 910 against biasing spring 595 indicates that the near boiler pressure has risen somewhat from its level during the startup. With this rise of pressure, the upward action of diaphragm 910 lifts the slidable rocker arm bracket 810, relocating the pivot point 800 of the rocker lever 625 to the elevated position best seen in FIGs. 8 and 11. The small piston 620 is now acting to close the inlet valve 88', allowing the engine 500 to operate in the expanding condition of the "Running Mode." The residual pressure at the near BDC is stored in the residual chamber 218 and helps boost the closing action of small piston 62. The closing actually occurs at the near TDC position allowing for this expansion and the working piston 30a' is nearing the BDC position and the exhaust ports.

[0063] Step 8 (FIG. 20)

[0064] FIG. 20 shows the opening action of the wedges 592, 593 of the main piston 30a' and the inlet valve 88', respectively, while in the "Running Mode." FIG. 20 also shows the engine 500 operating at its maximum near boiler pressure condition with the pressure regulator diaphragm 910 at its maximum upward position, moving the pivot point 800 to its maximum upward position, as shown in FIGs. 9 and 12.

[0065] Step 9 (FIG. 21)

[0066] FIG. 21 shows the continued operation of the engine 500 in the "Running Mode" at its maximum boiler pressure condition. The tandem action of the two small pistons 620 and 62 with rocker arm 625 is now in its full swing action. The operational states of engine 500 as shown in FIGs. 20-21 repeat when the engine 500 is in the "Running Mode."

[0067] Step 10 (FIG. 22)

[0068] FIG. 22 shows the closing down of the engine 500 back into its "Startup Mode" position. FIG. 22 shows the engine 500 settling back into the original position. However, in reality, the final position of the working piston 30a' and open/close position of the inlet valve 88' can be in any position. The sequential action of all three cylinders of the engine 500 will settle into a position such that at least one of the three cylinders will be left open to insure the startup of the engine when sufficient boiler pressure is made available. As can be seen in FIG. 22, the slidable rocker arm bracket 810 returns, under action of biasing spring 595, to its initial lower position shown in FIGs. 7 and 10.

[0069] FIGs. 23-32 are cross sectional views showing engine 2300 in accordance with a further embodiment. This embodiment

[0070] (1) replaces the sliding plate 88' of the previously disclosed embodiments with a poppet valve 2388 and [0071] (2) puts a curve 2391 on the contact face of the wedge 2392 on the piston 30a' to address the shock of the contact in rapid action. It is within the scope of the present invention to separately implement any or both of these features in other embodiments.

[0072] Although the poppet valve action can be up and down, the action in engine 2300 is kept sideway as shown in FIGs. 23-32 for the following reasons:

[0073] (1) The storage chamber 218 and the mechanism should be physically located between the high and low pressure areas of the working chamber 58 to minimize heat and pressure loss while allowing bleeding of condensation.

[0074] (2) The mechanism has multi-functions which need to be tightly consolidated, i.e., it self-starts the engine, it fine-tunes the mechanism addressing the varying residual pressure conditions, it addresses the varying high pressure conditions and the parabolic nature of the relative closing shutter speed rates of the inlet valve 2388, it allows for the opening means of the inlet valve 2388, i.e., the wedge action of the piston 30a' on the inlet valve 2388 would be smooth and deliberate.

[0075] (3) Maintaining the uniflow configuration retains the high and low temperature conditions in the working chamber 58, keeps the exhaust means simple, allows for directional flow through the working chamber 58 thus minimizing turbulence.

[0076] Although it is within the scope of the present invention to allow for the exhaustion of the residual working fluid during the up stroke as disclosed in the previous patents listed at the beginning of this specification, engine 2300 eliminates this device for the following reasons:

[0077] (1) It adds complexity that does not necessarily reap increased efficiency.

[0078] (2) For a heat engine, recompressing the working fluid has the positive advantage of retaining the residual heat in recompression so that the pressure jump with the new injection of working boiler fluid is not as great.

[0079] Finally, fluidics means can replace some of the mechanical means, such as lever 2390, in the inlet valve opening mechanism. [0080] The operation of engine 2300 is substantially similar to the operation of engine 500, except for the closing/opening of the inlet valve 2388, and will be briefly disclosed herein below.

[0081] Step 1 (FIG. 23)

[0082] The uniflow engine 2300 is in its startup mode. At least one of the inlet valves 2388 (shown in FIG. 23) of the three working chambers 58 in the three corresponding cylinders of the engine 2300 is open to the boiler pressure once that pressure is released to the engine 500. The position of diaphragm 910 in FIG. 13 indicates the acting pressure is at a lower working level.

[0083] Step 2 (FIG. 24)

[0084] In FIG. 24, the major change, compared to FIG. 23, is that the main piston 30a' of the working chamber 58 in the working cylinder has moved down, uncovering access port 112. This accessing allows the pressure in the working chamber 58 to enter the residual chamber 218 so as to act on small piston 62. Inlet valve 2388 is still open until the very end of Step 2.

[0085] Step 3 (FIG. 25)

[0086] Between Step 2 and Step 3, inlet valve 2388 is closed by the accessed pressure of the working chamber 58 acting on small piston 62.

[0087] Step 4 (FIG. 26)

[0088] The engine 2300 is still in the "Startup Mode." The inlet valve 2388 is still closed. The only change in FIG. 26 compared to FIG. 25 is the working piston 30a' has come up to contact with the lever 2390 pivotable about axis 2396. Due to the curve 2391 of wedge 2392, there is no abrasive contact between the contacting parts, the action is smooth.

[0089] Step 5 (FIG. 27)

[0090] FIG. 27 shows the opening action of the inlet valve 2388 with the continued upward movement of the working piston 30a' to the top dead center (TDC). hi particular, lever 2390 is moved by wedge 2392 to act on the valve rod 64 of inlet valve 2388, thereby opening the inlet valve 2388. When the inlet valve 2388 is open, the boiler pressure rapidly enters the working chamber 58 as shown by arrow Z.

[0091] Step 6 (FIG. 28)

[0092] FIG. 28 features the mode change from the "Startup Mode" to the "Running Mode" In FIG. 28, the only changes, compared to FIG. 27, are the sliding action of the blocker arm 116, the closing of the check valve 108, and the continued down stroke of the working piston 30a'. At this point the engine 2300 has shifted into the "Running mode." The slidable rocker arm bracket 810 is still at the lowest position.

[0093] Step 7 (FIG. 29)

[0094] FIG. 29 shows the engine 2300 in the "Running Mode." Diaphragm 910 moves upward against biasing spring 595 due to the rising boiler pressure. The upward action of diaphragm 910 lifts the slidable rocker arm bracket 810, relocating the pivot point 800 of the rocker lever 625 to the elevated position.

[0095] Step 8 (FIG. 30)

[0096] FIG. 30 shows the opening action of the wedge 592 of the main piston 30a' and the lever 2390 of the inlet valve opening mechanism while in the "Running Mode." FIG. 20 also shows the engine 2300 operating at its maximum near boiler pressure condition with the pressure regulator diaphragm 910 at its maximum upward position, moving the pivot point 800 to its maximum upward position.

[0097] Step 9 (FIG. 31)

[0098] FIG. 31 shows the continued operation of the engine 2300 in the "Running Mode" at its maximum boiler pressure condition. The tandem action of the two small pistons 620 and 62 with rocker arm 625 is now in its full swing action. The operational states of engine 2300 as shown in FIGs. 30-31 repeat when the engine 2300 is in the "Running Mode."

[0099] Step 10 (FIG. 32)

[00100] FIG. 32 shows the closing down of the engine 500 back into its "Startup Mode" position. The slidable rocker arm bracket 810 returns, under action of biasing spring 595, to its initial lower position. [00101] FIGs. 33-42 are cross sectional views of engine 3300 in accordance with a further embodiment. FIGs. 43-52 are cross sectional views of engine 4300 in accordance with a further embodiment. FIGs. 53-62 are cross sectional views of engine 5300 in accordance with a further embodiment. These embodiments use magnetic resistance means for controlling the closing rate of the inlet valve 2388. The magnetic resistance means can be controlled by the above disclosed diaphragm 910 (engine 3300) or any other suitable means such as microprocessors (engines 4300 and 5300).

[00102] These improvements, in addition to

[00103] (1) replacing the sliding plate 88' of the previously disclosed embodiments with a poppet valve 2388, and

[00104] (2) putting a curve 2391 on the contact face of the wedge 2392 on the piston 30a' to address the shock of the contact in rapid action,

[00105] further

[00106] (3) eliminate the rocker arm 625 by placing pistons 62 and 620 on the same axis or rod 64/640,

[00107] (4) replace the blocking means 116 for piston 620 of the previously disclosed embodiments with a valve 3800 that operates with the same action of blocking arm 116 connected to the centrifical mode changing governor,

[00108] (5) replace the mechanism 630 (described in U.S. Patent No. 6,505,538) with the improved lever means 3630 which has the same function of maintaining the check valve 108 open during startup, and

[00109] (6) replace the variable pivot point 800 of the now eliminated rocker arm 625 with a magnetic resistance means 8103/8104/81 to address the parabolic curve resistance required to align the closing rate of the inlet valve 2388 with the straight line relational pressure changes disclosed above.

[00110] As can be seen in FIGs. 33-42, the magnetic resistance means 8103/81 is mechanically controlled by diaphragm 910 in a manner similar to pivot point 800 of the rocker arm 625 in the previous embodiments. The magnetic resistance means 8104/81 can also be electrically controlled as shown in FIGs. 43-62, using one or more electronic controllers, e.g., computer chips, 9004. In particular, the controller 9004 is equipped with or connected to a pressure/temperature sensitive means, such as a temperature or pressure sensor, 9104, and is programmed, either by software or hardwiring, to address the high and low pressure/temperature conditions at Top Dead Center (TDC) and Bottom Dead Center (BDC) positions within the working chamber 58 of each cylinder. The cylinders of the engine in these embodiments can be commonly controlled by a single controller 9004. hi the embodiments of FIGs. 43-62, the controller 9004 regulates an electric magnetic coil 8104 or the like to control the closing rate of the inlet valve 2388. It is within the scope of the present invention to use any other suitable controllable retarding devices, e.g., electrostatic, hydraulic or mechanical devices etc., in place of the magnetic resistance means. Similar to the previously disclosed embodiments, the pressure regulator 900 or the pressure sensor 9104 of controller 9004 is constantly accessed to the pressure available from the boiler.

[00111] Since the small pistons 62 and 620 as well as inlet valve 2388 of engines 3300, 430, 5300 are all disposed on the same axis 64/640, the inlet valve closing mechanisms in the engines are referred to as single-axis valve mechanism. Other arrangements are, however, not excluded.

[00112] The operation of engines 3300, 4300, 5300 is relatively similar to the operation of the previously disclosed engines and will now be briefly described

[00113] Step 1 (FIGs. 33, 43, 53)

[00114] The uniflow engine (3300, 4300, 5300) is in its startup mode with the valve means 3116 locked in a closed position. At least one of the inlet valves 2388 of the three working chambers 58 of the engine (3300, 4300, 5300) is open to the boiler pressure once that pressure is released to the engine. Met valve 2388 is in the open position.

[00115] Step 2 (FIGs. 34, 44, 54)

[00116] The major change, compared to Step 1, is that the main piston 30a' of the chamber 58 of the working cylinder has moved down uncovering access port 112. This accessing allows the pressure in the working chamber 58 to enter the residual chamber 218 so as to act on small piston 62 which in turn closes the inlet valve 2388. Inlet valve 2388 is closed by the accessed pressure of the working chamber 58 acting on small piston 62. [00117] Step 3 (FIGs. 35, 45, 55)

[00118] Inlet valve 2388 is closed and the exhaust ports 512 of the engine (3300, 4300, 5300) are uncovered through the complete downstroke of the working piston 30a'. The RPMs of the engine during startup will be very low, and requires only sufficient rotational inertia to insure the continued running when the engine shifts into the more efficient "Running Mode." The check valve 108 must be held open allowing the pressure acting on small valve 62 to exhaust (arrow Y in FIG. 35) when the working cylinder exhaust.

[00119] Step 4 (FIGs. 36, 46, 56)

[00120] The engine is still in the "Startup Mode." The inlet valve 2388 is still closed. The only change is the working piston 30a' has come up to contact with the lever 2390 of the opening mechanism. The action is relatively smooth due to the curve 2391 on wedge 2392 of piston 30a'.

[00121] Step 5 (FIGs. 37, 47, 57)

[00122] These figures show the opening action of the inlet valve 2388 with the continued upward movement of the working piston 30a' to the top dead center (TDC). All other components remain substantially the same compared to Step 4. When the inlet valve 2388 is open, the boiler pressure rapidly enters the working chamber.

[00123] Step 6 (FIGs. 38, 48, 58)

[00124] This step features the mode change from the "Startup Mode" to the "Running Mode" through the action of arm 3116 which is acted on by the centrifical governor attached to the main drive shaft in the manner similar to blocking arm 116 in the previous embodiments. Other speed and/or inertia sensitive devices, such as RPM reading elements/sensors, can be used in place of the centrifical governor. The downward action of arm 3116 opens the valve 3800 which allows access of the working pressure at TDC to act on small valve 620 to close the inlet valve 2388. With this action, the slack in line 3117 connecting arm 3116 and bracket 3630 allows the bracket 3630 to rotate and check valve 108 connected thereto to close. When check valve 108 closes, it retains the residual pressure P_BDC collected through port 112 from the expanded pressure of the working chamber 58 in residual chamber 218. [00125] Step 7 (FIGs. 39, 49, 59)

[00126] In this step, the major changes, compared to Step 6, are the rotational action of the bracket 116 and the closure of check valve 108. At this point the engine (3300, 4300, 5300) has shifted into the "Running mode." The down stroke of the working piston 30a' uncovers port 112 allowing for the pressure at BDC to be stored in the residual chamber 218 and act on small piston 62. In these embodiments, the small piston 620 is now acting in tandem with the small valve 62 to close the inlet valve 2388, allowing the engine to operate in the expanding condition of the "Running Mode." As mentioned, the residual pressure P_BDC at the near BDC is stored in the residual chamber 218 and helps boost the closing action of small piston 62. Note that the closing actually occurred at the near TDC position allowing for this expansion and that the working piston 30a' is nearing the BDC position and the exhaust. In addition, since the boiler pressure has risen from its initial level, diaphragm 910 in engine 3300 (FIG. 39) moves slightly upward against biasing spring 595 due to the rising boiler pressure. The upward action of diaphragm 910 moves the magnet 8103 slightly away from its counterpart 81 in the magnetic resistance mean. As a result, the magnetic resistance caused by attraction between magnets 8103 and 81 is reduced, allowing the inlet valve 2388 to be closed at a faster speed. It should be noted that the strength of the magnetic resistance is a parabolic function of the square of the distance (d²) between elements 81 and 8103. Since the closing rate is also a parabolic function as explained above, the straight-line variation of the action of P_TDC pressure on the diaphragm 910 will produce the desired parabolic resistance function so that the closing rate of inlet valve 2388 is at its optimum.

[00127] In a similar fashion, the controller 9004 in engines 4300 and 5300 converts the increased boiler pressure/temperature into a corresponding current fed to the electro magnetic coil 8104. The higher the boiler pressure/temperature sensed by sensor 9104, the lower the converted current, although other arrangements are not excluded. As a result, the magnetic resistance caused by attraction between magnet 81 and coil 8104 is progressively reduced in accordance with the progressively increasing pressure/temperature, allowing the inlet valve 2388 to be closed at a progressively faster speed. The current is controlled by controller 9004, in an embodiment, to vary to match the straight line pressure/temperature relationship with the parabolic relationship of the closing rate so that the closing rate of inlet valve 2388 is at its optimum. However, due to the programming capability/flexibility of controller 9004, any other suitable pressure/temperature-to-current conversion characteristics can be used depending on particular application.

[00128] In alternative embodiments, element 81 need not be a magnet; it is sufficient to be a magnetically attractable element. Likewise, in engine 3300, element 8103 need not be a magnet; it is sufficient to be a magnetically attractable by magnet 81.

[00129] Step 8 (FIGs. 40, 50, 60)

[00130] This step features the opening action of the inlet valve 2388 while in the "Running JVfode.'^, FIG. 40 shows the engine 3300 operating at its maximum near optimum boiler pressure condition with the pressure regulator diaphragm 910 at its maximum upward position, moving the magnet 8103 further away from magnet or magnetically attractable element 81. Likewise, the controller 9004 in FIGs. 50, 60 is programmed, in accordance with an embodiment, so as to eliminate or at least minimize the current running in coil 8104. The resistance provided by the magnetic resistance means of engines 3300, 4300, 5300 is close to zero in this step. As a result, inlet valve 2388 is closed at its maximum speed.

[00131] Step 9 (FIGs. 41, 51, 61)

[00132] This step features the continued operation of the engine (3300, 4300, 5300) in the "Running Mode" at its maximum boiler pressure condition. The operational states of the engine (3300, 4300, 5300) in Steps 8 and 9 repeat when the engine is in the "Running Mode."

[00133] Step 10 (FIGs. 42, 52, 62)

[00134] This step features the closing down of the engine (3300, 4300, 5300) back into its "Startup Mode" position. The upper magnet/magnetically attractable element 8103 returns, under action of biasing spring 595, to its initial lower position. Likewise, in engines 4300, 5300, the current in coil 8104 is at its maximum corresponding to the minimum pressure/temperature in the boiler. In a further embodiment, the current can be completely shut down and will be turned back on, at the maximum level, upon startup.

[00135] Engine 5300 is different from engine 4300 in that it further includes a second temperature and/or pressure sensor 9105 which senses the conditions at the BDC. Controller 9004, based on the conditions at both TDC and BDC collected by sensors 9104 and 9105, respectively, can accurately vary the current in coil 8104 to assure the optimum closing rate of the inlet valve 2388 at all time.

[00136] FIG. 63 is a schematic view of an engine 6300 in accordance with a further embodiment. Although in some embodiments of the present invention, a mechanical or non¬ electric/electronic solution will be more cost/efficient for a small engine and/or in remote areas and/or when substantially maintenance-free working conditions are desirable, the embodiments disclosed below are provided taking into account today's bias toward using electronics in the market.

[00137] In particular, engine 6300 includes a poppet valve 6388 which, unlike the previous embodiments, moves up and down rather than sideways. The poppet valve 6388 performs the function of the inlet valve 88', 2388 in the previous embodiments. Engine 6300 further includes two chambers A and B on each side of a small driving piston A/B of the poppet valve 6388. The driving piston A/B performs the combined functions of the small pistons 62, 620 in the previous embodiments.

[00138] In this embodiment, controller 9004 of the embodiments disclosed with respect to FIGs. 43-62 is retained and is programmed and/or hardwired to function in substantially the same manner. However, instead of converting the conditions detected by sensors 9104, 9105, respectively, into a current to be fed to an electromagnetic coil, controller 9004 issues an electronic, e.g., digital, signal, via wiring 6372, to a swivel switch valve 6371 causing a switching of the pressure from the boiler pressure and the negative or vacuum pressure near the BDC back and forth between the two chambers A and B on either side of the small piston A/B operating the inlet poppet valve 6388. The actual closing rate of poppet valve 6388 depends on may factors, such as its nominal closing rate, the reaction time of swivel switch valve 6371 etc. The factors are programmed and/or hardwired into controller 9004 to ensure optimum actual closing rate of inlet valve 6388.

[00139] Alternatively or additionally, controller 9004 in engine 6300 is programmed and/or hardwired to adjust the closing timing of poppet valve 6388 depending on one or more of the conditions sensed by the sensors 9104, 9105 and the speed/inertia of engine 6300. As discussed above, in the Running mode of the previously disclosed engines, the inlet valve 88', 2388 is closed as soon as the piston 30a', after leaving the TDC, uncovers a port allowing PTD_C to act on small piston 620 to close the inlet valve. The function of such port is now performed in engine 6300 by controller 9004 which determines the timing for closing poppet valve 6388 shortly after piston 30a' leaves the TDC. Controller 9004 controls the timing based on, e.g., a position sensor detecting the position of the piston 30a', or a timer which counts time lapsed after disconnection between electric contact switch 6374 (described herein after) and a probe 6375 (described herein after) mounted on the head of piston 30a'. Other devices that can report the position of piston 30a' to controller 9004 can be used.

[00140] Likewise, in the Startup mode, the inlet valve 88', 2388 of the previous embodiments is kept open, e.g., by rod 116 or 3116, until piston 30a' uncovers port 112 near BDC. The function of rod 116/3116 is now performed in engine 6300 by controller 9004 which delays the closing of the poppet valve 6388 until a position sensor, a timer counting time lapsed after disconnection between electric contact switch 6374 and a probe 6375, or any suitable device reports that piston 30a' has reached the position near BDC. The delay in closing poppet valve 6388 is also adjustable by controller 9004 in the Startup mode based on the speed or inertia of the engine 6300 which is detected either by the governor used in the previously disclosed embodiments, or a tempo reading device (described herein after), or any other suitable means.

[00141] Finally, in engine 6300, the mode switching from the Startup mode to the Running mode is done internally, i.e., programmably or by way of hardwiring, in controller 9004 when a tempo reading device (described herein after) or any suitable speed/inertia sensitive device reports to controller 9004 that the speed or inertia of engine 6300 has reached a predetermined level allowing optimum expansion of the working fluid. Controller 9004 will then remove the delay, which was imposed on the closing timing of the poppet valve 6388 during the Startup phase, and allow poppet valve 6388 to close shortly after piston 30a' leaves TDC. In the Running mode, the fine tuning of the closing speed of the inlet valve based on at least one of the pressures or temperatures near or at TDC and BDC, as discussed with respect to the previous embodiments, is performed in controller 9004.

[00142] In the embodiment of engine 6300, like in the previous embodiments, the boiler pressure outside the chamber 58 is greater than the pressure in the working chamber 58 after the poppet valve 6388 closes. However, unlike the previously disclosed embodiments where the boiler pressure outside the chamber 58 tends to keep the inlet valve 2388 in the closed position, the boiler pressure outside the chamber 58 in this embodiment tends to push the poppet valve 6388 into the open state, as the poppet valve 6388 opens into the working chamber 58. To maintain the poppet valve 6388 closed during the downstroke of the working piston 30a', (a) the boiler pressure (rather than the pressure in the working chamber 58) and the vacuum or negative pressure near BDC are acting on the small piston A/B, and (b) the surface area of the driving piston A/B is larger than that of the poppet valve 6388. Not only does this insure that the poppet valve 6388 remains closed during the down stroke, but the poppet action will also be much smoother. Other arrangements with various valve types, such as inlet valves 88 and 2388, being used instead of poppet valve 6388 are not excluded from the scope of the present invention.

[00143] The small piston A/B will move between the two small chambers A and B. On the far side away from the poppet valve 6388 is small chamber A which uses the boiler pressure to act on small piston A/B to drive the poppet valve 6388 open. On the near side toward the poppet valve 6388 is small chamber B which also uses the boiler pressure to act on small piston A/B to close the poppet valve 6388. More particularly, the boiler pressure acts on the A side of piston A/B and the negative vacuum pressure acts on the B side of piston A/B to open the poppet valve 6388. And the boiler pressure acts on the B side of piston A/B and the negative vacuum pressure acts on the A side of piston A/B to close the poppet valve 6388. Swivel valve 6371 switches the boiler pressure and the vacuum pressure between these two small chambers A and B. This back and forth access between the boiler pressure and the exhaust pressure to the small piston A/B is controlled by the swivel switch valve 6371.

[00144] When the pneumatic valve or piston A/B is closing the inlet poppet valve 6388, the swivel switch valve 6371 is controlled by the controller 9004 based on the conditions, such temperature and/or pressure detected by sensors 9004, 9005. When the pneumatic valve or piston A/B is opening the inlet poppet valve 6388, the swivel switch valve 6371 is controlled, in accordance with an embodiment, directly, via wiring 6376, by an electric contact switch 6374. A probe 6375 for actuating the electric contact switch 6374 is mounted on the head of the main piston 30a' and inserts into the electric contact switch 6374 to make contact while at the Top Dead Center position. In this embodiment, switch 6374 and probe 6375 function as the wedge/lever and wedge/wedge arrangements disclosed above. In a further embodiment, the wiring 6376 runs not directly to swivel valve 6371, but to controller 9004 which will issue appropriate switching signal upon contact between switch 6374 and probe 6375, thereby implementing centralized control, hi a further embodiment, a position sensor which is magnetically and/or optically and/or mechanically actuable and located near TDC can be used as an alternative to the switch/probe arrangement.

[00145] The following description addresses the closing means for pneumatic valve or piston A/B in the Startup and Running Modes.

[00146] During the Startup Mode, controller 9004 gives an electronic signal to the swivel switch valve 6371 causing the boiler pressure to enter the small chamber A and causing the vacuum sink to be accessed to small chamber B. This action opens the inlet poppet valve 6388. The inlet poppet valve 6388 will remain open throughout the downstroke until the working piston 30a' reaches near Bottom Dead Center.

[00147] As disclosed in the prior patents listed at the beginning of this specification, each cylinder stroke carries the drive shaft 180° from Top Dead Center to Bottom Dead Center. Because the engine has three cylinders, each driving piston is given a one third segment or 120° before the sequential driving piston will fall into action. This provides a 60° overlap between the first and second pistons which can be used to insure a transfer of force from the first to the sequential piston before exhausting the driving fluid of the uniflow engine to the condenser sink at BDC.

[00148] Returning now to engine 6300, in the start up mode, the poppet valve 6388 must close before the main piston 30a' uncovers the exhaust (not shown in FIG. 63) of the uniflow engine 6300. There are several ways that the engine 6300 can register the closing action of the inlet poppet valve 6388 before the main piston 30a' uncovers the exhaust ports.

[00149] In an embodiment, there is provided a sequential tempo device comprising a number, e.g., three, of points on a member, e.g., a disc (that is rotating with the drive shaft), that make electric contact or are otherwise activated at the exact positions needed to send an electric signal to the controller 9004 which will determine whether the engine 6300 has enough rotational inertia to switch the engine 6300 from the start up to the running modes, or just close the inlet poppet valve 6388. After the determination by controller 9004 as to whether the RPMs or rotational inertia is/are sufficient to enter the Running mode, an electric signal is sent by controller 9004 to the swivel switch valve 6371 which in turn switches the pneumatic access to A and B chambers thus closing the inlet poppet valve 6388. The contact activating points are located so as to electrically and/or magnetically and/or mechanically and/or optically actuate a signal to the controller 9004 and then the swivel switch valve 6371 to close the inlet poppet valve 6388 after the rotational movement passes the 120° point and before the driving piston 30a' reaches the engine exhaust.

[00150] hi a further embodiment, a position sensor located near or adjacent sensor 9105 can be used to report the actual position of piston 30a' to controller 9004 which will determine upon receiving a signal from said position sensor that it sis time to close poppet valve 6388. The time interval between successive appearances of piston 30a' at or near BDC can be used by controller 9004 to judge the engine speed, i.e., RPMs, and the moment of switching the engine 6300 into the Running mode.

[00151] When closing the inlet poppet valve 6388, the swivel switch valve 6371 will reverse the access of the small chamber A from the boiler pressure to the vacuum pressure and the access of small chamber B from the vacuum pressure to the boiler pressure. This action will close the inlet poppet valve 6388.

[00152] In the Running Mode, when sufficient rotational momentum or RPMs is/are developed, the engine 6300 will shift from the state up mode to the running mode. The level of momentum could be measured by a centrifical governor or by a sequential tempo device or by the BDC position sensor disclosed above. Other arrangements are, however, not excluded.

[00153] When the engine 6300 shifts to the running mode, the fluid in the working chamber 58 of the engine 6300 will expand to maximize the work output of each stroke. This requires that the inlet poppet valve 6388 be open only momentarily to allow the proper amount of working fluid to enter the working chamber 58 before expansion, as disclosed above.

[00154] As explain in the description of the start up mode, the closing of the inlet poppet valve 6388 in the running mode is caused by reversing the access of small chamber A from the boiler pressure to the vacuum pressure and accessing of small chamber B from the vacuum pressure to the boiler pressure in the same way described earlier. However, the closing in the running mode would occur at the TDC position to maximize the efficiency of the expanded fluid in the working chamber. The timing of this closing rate would be determined by reading the high boiler pressure at TDC and the low condenser sink vacuum pressure at BDC and by running this pressure data through the controller 9004 to signal to the swivel switch valve 6371 to pneumatically reverse its action to close the inlet poppet valve 6388 at or near TDC. [00155] The inlet poppet valve 6388 is actuated by probe 6375 which is mounted on the head of the driving piston 30a'. The inlet poppet valve 6388 opens in the same way whether the engine is in the Start up or Running Modes, i.e., the opening occurs when probe 6375 makes contact with electronic switch 6374 which is either directly connected to the swivel switch valve 6371. However, since the opening action is the same with all up strokes whether in the Start up or Running Modes, electronic contact switch 6374 does not need to run through the controller 9004 for actuating the swivel switch valve 6371. Nevertheless, it is within the scope of the present invention to connect switch 6374 and swivel switch valve 6371 indirectly, e.g., via controller 9004, for various purposes, such as centralized control, testing, control overriding etc.

[00156] hi a further embodiment, swivel switch valve 6371 can be replaced by a number, e.g., four, valves each individually connecting one of the Pχoc and P_BDC to one of chambers A and B. The valves (not shown) will be controlled by controller 9004 to open/close poppet valve 6388 by switching the pressures in chambers A and B as described above.

[00157] As disclosed above, where the pressure difference ΔP between P_TDC and P_BDC is used to close the inlet valve 88, 2388, 6388, it is desirable that the parabolic characteristic of the inlet valve closing rate and the linear characteristic of ΔP are matched by additional closing assisting means, such as counter springs, variable lever arms, controllable magnetic and/or electric and/or hydraulic and/or mechanical retarding devices, hi engine 6300, the relationship matching is performed by controller 9004 with switch valve 6371.

[00158] Inlet valve 6388 can be open/closed electrically and/or magnetically and/or mechanically and/or hydraulically, rather than pneumatically as disclosed above, hi that case, the pressures at TDC and BDC may not be used to directly open/close the inlet valve, but are used to , provide information to controller 9004 to assist it in determining the open/close timings of the inlet valve.

[00159] While the foregoing disclosure shows illustrative embodiments, it should be noted that various changes and modifications could be made herein without departing from the scope of the described embodiments as defined by the appended claims. Furthermore, although elements of the described embodiments may be described or claimed in the singular, the plural is contemplated unless limitation to the singular is explicitly stated.

Claims

1. In a multi-cylinder, single crankshaft, reciprocating piston engine with at least three cylinders distributed along a common crankshaft to provide a rotational output upon provision thereto of a supply of an expandable working fluid at a predetermined initial condition, an inlet valve closing mechanism for closing a movable inlet valve at each cylinder, the inlet valve having an open position to start the inflow of working fluid into the cylinder and a closed position to stop the inflow of the working fluid into the cylinder, said inlet valve closing mechanism comprising: a pressure responsive element coupled to a stem of said inlet valve and responsive at least to a pressure of the cylinder near or at TDC for driving the inlet valve to a closed position thereof; and a control element for adjusting at least one of a closing timing and a closing speed of said inlet valve being imparted by said pressure responsive element.

2. The inlet valve closing mechanism of claim 1, wherein said control element is operable to correlate (a) a linear relationship between a force made available by the pressure responsive element for closing the inlet valve and the pressure acting upon said pressure responsive element, with (b) a parabolic relationship between a force required for closing the inlet valve at a predetermined speed and the time available for said closing.

3. The inlet valve closing mechanism of claim 1, further comprising a speed responsive mechanism responsive to a rotational speed of said engine and coupled to said control element for providing said control element with a setting indicative of the engine speed; wherein said control element is operable to adjust said at least one of the closing timing and the closing speed of said inlet valve in accordance with said setting.

4. The inlet valve closing mechanism of claim 1, wherein said control element is operable to non-linearly increase the closing speed of said inlet valve when a parameter of said working fluid supplied to said cylinder increases.

5. The inlet valve closing mechanism of claim 4, wherein control element comprises a rocker lever having a fulcrum moveable depending on a value of said parameter of said working fluid supplied to said cylinder.

6. The inlet valve closing mechanism of claim 5, further comprising a diaphragm displaceable under action of a pressure of said working fluid supplied to said cylinder, said diaphragm being coupled to said fulcrum of the rocker lever for moving the fulcrum toward the stem of said inlet valve when the pressure of said working fluid supplied to said cylinder increases.

7. The inlet valve closing mechanism of claim 1, wherein said control element is operable to retard the closing speed of said inlet valve depending on a parameter of said working fluid supplied to said cylinder.

8. The inlet valve closing mechanism of claim 7, further comprising a magnetic coupling between the stem of said inlet valve and said control element for controllably resisting movement of said stem.

9. The inlet valve closing mechanism of claim 8, wherein a resistance provided by said magnetic coupling varies depending on a parameter of said working fluid supplied to said cylinder.

10. The inlet valve closing mechanism of claim 9, wherein said magnetic coupling comprises a first magnetically attractable element moveable relative to a second magnetically attractable element on said stem and in accordance with the parameter of said working fluid supplied to said cylinder.

11. The inlet valve closing mechanism of claim 10, further comprising a diaphragm displaceable under action of a pressure of said working fluid supplied to said cylinder, said diaphragm being coupled to said first magnetically attractable element for moving the first magnetically attractable element away from the second magnetically attractable element, thereby reducing the resistance provided by the magnetic coupling when the pressure of said working fluid supplied to said cylinder increases.

12. The inlet valve closing mechanism of claim 9, wherein said magnetic coupling comprises a magnetizable element and a magnetically attractable element one of which is on said stem, a magnetic field of said magnetizable element being variable in accordance with the parameter of said working fluid supplied to said cylinder.

13. The inlet valve closing mechanism of claim 12, wherein said magnetizable element comprises a coil adjacent said magnetically attractable element on the stem; said inlet valve closing mechanism further comprising a controller electrically coupled to said coil for varying a current running in said coil depending on the parameter of said working fluid supplied to said cylinder.

14. The inlet valve closing mechanism of claim 13, further comprising a first sensor for sensing the parameter of said working fluid supplied to said cylinder, said sensor being coupled to said controller which is a microcomputer programmed and/or hardwired to convert the sensed parameter to the current running in the coil.

15. The inlet valve closing mechanism of claim 14, further comprising a second sensor for sensing a pressure of said cylinder near or at BDC, wherein the first sensor is a pressure sensor and both sensors are coupled to said controller to supply the sensed pressure thereto, said controller being arranged to vary the current running in said coil depending on both said sensed pressures.

16. The inlet valve closing mechanism of claim 1, wherein said control element is operable to delay the closing timing of said inlet valve when a speed of said engine is below a predetermined level.

17. The inlet valve closing mechanism of claim 16, wherein said control element comprises an electronic controller operable to selectively couple pressures of said cylinder near or at TDC and BDC to two chambers on opposite sides of a piston positioned on the stem of said inlet valve, thereby closing or opening said inlet valve with the pressure near or at TDC and BDC.

18. The inlet valve closing mechanism of claim 17, further comprising a swivel switch valve coupled between TDC and BDC of said cylinder and said chambers, said swivel switch valve being controlled by said controller to open and close said inlet valve.

19. The inlet valve closing mechanism of claim 17, further comprising a sensor for sensing a parameter of the working fluid; said sensor being positioned either (i) in a pipe disposed upstream of the inlet valve for supplying the working fluid to the cylinder, or (ii) in the cylinder near or at TDC.

20. The inlet valve closing mechanism of claim 1, wherein said control element is operable to retard the closing speed of said inlet valve when a speed of said engine is below a predetermined level.

21. The inlet valve closing mechanism of claim 20, wherein said control element comprises a counter spring acting against a closing direction of said inlet valve.

22. A multi-cylinder, single crankshaft, reciprocating piston engine having at least three cylinders distributed along a common crankshaft to provide a rotational output upon provision thereto of a supply of an expandable working fluid at a predetermined initial condition; said engine further comprising an inlet valve closing mechanism for closing a movable inlet valve at each cylinder, the inlet valve having an open position to start the inflow of working fluid into the cylinder and a closed position to stop the inflow of the working fluid into the cylinder; said inlet valve closing mechanism comprising: a pressure responsive element coupled to a stem of said inlet valve and responsive at least to a pressure of the cylinder near or at TDC for driving the inlet valve to a closed position thereof under action of said pressure; and a control element for adjusting at least one of a closing timing and a closing speed of said inlet valve being imparted by said pressure responsive element.

23. A multi-cylinder, single crankshaft, reciprocating piston engine having multiple cylinders distributed along a common crankshaft, to provide a rotational output upon provision thereto of a supply of an expandable working fluid at a predetermined initial condition, said engine further comprising pressure detecting elements arranged to collect data related to pressures at or near TDC and BDC in each cylinder; a mechanism for closing an inlet valve at each cylinder, the inlet valve having an open position to start the inflow of working fluid into the cylinder and a closed position to stop the inflow of the working fluid into the cylinder; and an electronic control element coupled to said pressure detecting elements to receive said data, said electronic control element being further coupled to said mechanism and configured to cause said mechanism to close the inlet valve, at a closing rate or timing determined by said controller based on the received data, using at least one of the pressures at or near TDC and BDC of the cylinder.