GB2101226A

GB2101226A - High pressure vapour driven engines, and power plants including such engines

Info

Publication number: GB2101226A
Application number: GB08119268A
Authority: GB
Inventors: Edward W Crane
Original assignee: STAR MOTORS Co
Current assignee: STAR MOTORS Co
Priority date: 1981-06-23
Filing date: 1981-06-23
Publication date: 1983-01-12

Abstract

A swash-plate engine is disclosed having a plurality of cylinders (15) arranged around a rotatable shaft (20). A swash-plate (22) is rotatably mounted on the shaft and is connected to pistons (16) in the cylinders (15) by connecting rods (36), each end of each connecting rod being connected to the piston or swash- plate (22), as appropriate, by a ball joint (38) and the swash-plate being prevented from rotating around the shaft axis by a pin (56) engageable in an arcuate groove 58. Spring-biased slide valves (74) are provided for controlling intake to and exhaust from the cylinders of a high-pressure vapour, the valves being operated by a cam (66) on the shaft (20). The engine may be used in a closed cycle power plant including a pair of heat exchangers and a pump. <IMAGE>

Description

SPECIFICATION High pressure vapour driven engines and power plants including such engines This invention relates to high pressure vapour driven engines, of the swash plate type, and also to apparatus, employing such engines, for converting heat into work.

A number of arrangements are known in swash plate engines for connecting the pistons to a swash plate ring. In some instances a rod is pinned at one end either to the piston or to the swash plate ring but not both and in other instances the rod is allowed merely to strike against the swash plate ring. In each of these instances certain disadvantages result such as increased wear on the cylinder walls due to the movement of the rod end attached to the swash plate through an arcuate path as the swash plate ring reciprocates and the like. Further many of the gas injection and recovery systems used in the known engines are bulky and complex and result in a valving arrangement of substantial size for use in conjunction with the engine.

According to a first of the present group of inventions, there is provided a high pressure vapour driven engine including an engine casing, a cylinder block positioned within said engine casing, a power output shaft rotatably positioned through said cylinder block, a plurality of cylinders provided in said cylinder block with their longitudinal axes substantially parallel to and equally spaced about a longitudinal axis of said power output shaft, a plurality of pistons reciprocally mounted in said cylinders, swash plate means, including a swash plate ring, positioned on said power output shaft, a rod operatively associating each of said pistons with said swash plate ring, injection means for injecting high pressure vapour into each of said cylinders, exhaust means for permitting the escape of vapour from each of said cylinders and control means for controlling the injection and exhaust of said vapour from said cylinders so that said pistons are reciprocated in said cylinders thereby transmitting power to said swash plate via said rods and causing said power output shaft to rotate, wherein there is provided connecting means on each end of each of said rods for rotatably connecting said rods to said pistons and said swash plate ring and stabilising means positioned on said swash plate ring for preventing rotation of said swash plate ring relative to said cylinders.

According to a second of the present group of inventions, there is provided a high pressure vapour driven engine including an engine casing, a cylinder block positioned within said engine casing, a power output shaft rotatably positioned through said cylinder block, a plurality of cylinders provided in said cylinder block with their longitudinal axes substantially parallel to and equally spaced about a longitudinal axis of said power output shaft, a plurality of pistons reciprocally mounted in said cylinders, swash plate means, including a swash plate ring, positioned on said power output shaft, a rod operatively associating each of said pistons with said swash plate ring, injection means for injecting high pressure vapour into each of said cylinders, exhaust means for permitting the escape of said vapour from each of said cylinders and control means for controlling the injection and exhaust of said vapour from said cylinders so that said pistons are reciprocated in said cylinders thereby transmitting power to said swash plate via said rods and causing said power output shaft to rotate, wherein there is provided a compact valve assembly, said valve assembly including a valve over each of said cylinders, said valves being positioned in a plane generally perpendicular to said longitudinal axis of said power output shaft with their inner ends being directed toward said longitudinal axis of said power output shaft, said valve assembly being adapted to receive a central high pressure vapour feed for distribution to each valve and an exhaust discharge receiving means for the recovery of a vapour discharge from each cylinder, said exhaust discharge receiver being positioned generally circumferentially about the outer ends of said valves for collecting said exhaust discharge for recovery through a discharge port.

In view of the weil-publicized worldwide shortage of petroleum products in recent years and the resulting increasingly higher prices for such products there has been an increasing interest in the production of energy from other sources. Considerably interest has been shown in the use of geothermal energy, solar energy and the like. In many such instances especially when solar energy is used, heat is recovered in a stream which while is contains considerable thermal energy is at a relatively low temperature. For instance, water heated to temperatures from about 1 400F (about 600C) up to the boiling point of water may be recovered from solar energy recovery systems. Similar water streams may also be recovered from geothermal sources, although energy may be recovered from such formations as steam at much higher temperatures.In many instances it is desirable to produce mechanical energy or work from such streams.

In accordance with a third one of the present inventions, there is provided a power plant for coverting heat into work comprising an engine according to said first or second invention, a first heat exchanger fluidly communicating said injection means and adapted to heat evaporable fluid at high pressure, a second heat exchanger fluidly communicating said exhaust means to cool said vapour; and a recycle means fluidly communicating said second heat exchanger and said first heat exchanger for recycling said cooled vapour from said second heat exchanger to said first heat exchanger to pressurise the vapour.

A specific embodiment of the present group of inventions will now be described by way of example, reference being made to the accompanying drawings, in which FIGURE 1 is a longitudinal-sectional view of an embodiment of a swash plate engine, according to the present group of inventions, taken at line A-A of FIGURE 2; FIGURE 2 is a sectional view of the swash plate engine shown in Figure 1 taken at the longitudinal axis of the valves which control the inlet and exhaust to the cylinders; FIGURE 3 is a sectional view of a section of FIGURE 2 showing a valve in an exhaust position; and FIGURE 4 is a schematic diagram of an apparatus for converting heat into work according to the present group of inventions.

In the description of the Figures the same numbers will be used to refer to the same components throughout.

In Figure 1, an embodiment of a swash plate engine 10 suitable for use in the present invention is shown. Engine 10 comprises a housing 12 which contains a cylinder block 14 which contains cylinders 1 5. A piston 1 6 is positioned in each cylinder 1 5 with a power output shaft 20 being rotatably positioned through cylinder block 1 4.

Cylinders 1 5 have their longitudinal axes 96 positioned substantially parallel to and are evenly spaced about a longitudinal axis 78 of output shaft 20 which also bears a swash plate 22 which comprises a drive hub 24 keyed to output shaft 20 by a key 26 to prevent rotation of drive hub 24 relative to shaft 20 with keepers 28 being positioned to prevent sliding of drive hub 24 on shaft 20. A swash plate ring 30 is rotatably positioned on drive hub 24 outside bearing means 32 to complete swash plate 22. Piston rods 36 connect pistons 16 and swash plate ring 30 with ball and socket joints 38 being used to connect rods 36 to both pistons 1 6 and swash plate ring 30.As known to those skilled in the art, pistons 1 6 include rings 1 8 to result in a seal between the outer diameter of pistons 16 and the inner diameter of cylinders 1 5. A thrust bearing 40 is positioned between cylinder block 1 4 and drive hub 24 to maintain shaft 20 in position. A shaft bearing 42 is positioned at the entry of shaft 20 into housing 12. Needle bearings 44 are positioned to support shaft 20 in cylinder block 14. An end plate 46 is positioned about shaft 20 to sealingly close housing 12 via a seal 48. An oil pump 50 is included for withdrawing oil via an oil line 52 from a sump and dispersing a fine spray of oil into the interior of engine 10, as known to those skilled in the art.Oil pump 50 is not shown in detail since no novelty is considered to reside in the oil pump per se. A swash plate stabilizer 54 comprising a member 56 extending generally outwardly from the outer edge of swash plate ring 30 and slideably engaging a slot 58 is shown. As swash plate ring 30 reciprocates stabilizer member 56 moves slideably in slot 58 and prevents rotation of swash plate ring 30 relative to cylinders 1 5. While stabilizer 54 is shown connected to cylinder block 1 4 it is recognized that slot 58 could be formed in housing 12 or other members so long as rotation of swash plate ring 30 relative to cylinders 1 5 is eliminated.

An end cap 68 is positioned over the other end of engine 10 and joined to housing 12 by a plurality of bolts 94. An eccentric 66 is positioned on an end of shaft 20 as shown between the cylinder heads 86 and end cap 68. A gas inlet 70 is positioned through end cap 68 to provide a gas flow to gas distribution passages 72. Passages 72 serve to direct a gas flow to valves 74 which comprise valve cylinders 80 containing valve pistons 82 which are generally co-axially positioned with the axis 76 of valves 74 being oriented in a plane generally perpendicular to axis 78 of shaft 20. Valve pistons 82 are biased toward axis 78 of shaft 20 by springs 84 positioned on each piston (shown in FIGURE 2). A port 88 is provided in each cylinder head for charging gas to each cylinder and exhausting gas from each cylinder.A gas outlet 90 is circumferentially positioned about the outer ends of valves 74 so that as gas is exhausted from port 88 it is discharged into gas outlet 90 for ultimate discharge to an exhaust 92. Valves 74 are generally positioned so that the axis 76 of each valve generally intersects cylinder axis 96 of the cylinder over which the valve is positioned and axis 78 of shaft 20.

FIGURE 2 shows the positioning of valves 74 when five cylinders are used. As indicated each valve is positioned over a cylinder generally shown in FIGURE 2 by circles 1 5 denoting the cylinders which are generally evenly spaced about the axis 78 of shaft 20. As will be noted one valve has opened to expose a port 88, so that gas is flowing into one cylinder in the view shown with two of the valves being open te exhaust gas from two cylinders. As discussed previously, each valve is positioned over a cylinder and is generally positioned so that its longitudinal axis intersects longitudinal axis 78 of shaft 20 and longitudinal axis 96 of its cylinder generally perpendicularly.

Gas outlet 90 is circumferentially positioned about the outer ends of valves 74 with a discharge exhaust 92 being shown in FIGURE 1.

In FIGURE 3, a valve 74 is shown in an exhaust position so that gas can flow from a cylinder through port 88 into gas outlet 90 and out through exhaust 92. A valve in a gas inlet position is shown in FIGURE 1, so that gas can flow through inlet 70, passage 72 and port 88 to cause piston 1 6 to move in cylinder 1 5.

In the operation of the swash plate engine gas flows into engine 10 through a suitable opening in valve piston 82 (shown as a reduced diameter section of piston 82) and port 99 into cylinder 1 5 thereby moving piston 16 away from cylinder head 86 to cause rod 36 to exert force on swash plate ring 30 which imparts rotary motion to drive hub 24 as it moves longitudinally with respect to shaft 20. The operation of such swash plate drive systems is well known to the art and need not be discussed further it being clear that as a first piston is moving outwardly with respect to cylinder head 86, at least one other piston will be moving toward its cylinder head 86 thus exhausting vapour from the other cylinder.

Eccentric 66 is formed to result in the alternate charging and discharging of vapor from cylinders 1 5 as the valves move from an open position as shown in FIGURE 1 with respect to the incoming gas to an exhaust position as shown in FIGURE 3 so that vapour can be exhausted from each cylinder.

In the operation of such engines, when the rods are rigidly fixed at either end i.e., to the pistons or to the swash plate ring, the movement of the swash plate ring which moves through an arcuate path imposes stress on the cylinders and pistons since the cylinder and piston arrangement is not adapted to accommodate the arcuate motion of the rod end attached to the swash plate ring. Such results in certain operating inefficiencies and accelerated wear. Similar disadvantages are incurred to a lesser extent when the end of the connecting rod contacting the swash plate ring is left free to merely strike the swash plate ring. Even in such instances there is a tendency to transmit the arcuate motion of the rod ends to the pistons and cylinders.Surprisingly beneficial results are accomplished in improving the efficiency and improving the wear life of the engine when both rod ends are rotatably connected to the piston and to the swash plate ring respectively. Such results in a considerable reduction of the stress on the pistons and cylinders. It is desirable in such an arrangement that a stabilizer be used to prevent rotation of swash plate ring 30 relative to cylinders 1 5 so that rods 36 remain generally oriented about longitudinal axis 96 of each cylinder. The combination of features thus described has been found to result in a surprisingly efficient and smooth operation of the improved swash plate engine of the present invention.

The valving arrangement described hereinbefore for injecting and exhausting vapour has been found to be surprisingly efficient and compact. As will be noted, the vapour inlet is positioned generally axially with respect to valves 74 so that passages for the high pressure vapour which can be relatively small are positioned centrally in plate 68. By contrast, gas outlet 90 which is receiving vapour under lower pressure as it is discharged is of necessity larger since the same quantity of gas occupies a larger volume at lower pressure. Gas outlet 90 is accordingly positioned circumferentially about the outer ends of valves 74 where a greater volume is available for gas collection. The gas is thereafter exhausted through a port 92 or the like which can be of substantially any suitable size.It will be observed that the arrangement discussed above results in the use of smaller passages in the central area of the engine where less space is available with the passages which require a larger volume being positioned about the perimeter of housing 1 2 so that the larger spaces occupy an area outside the area occupied by valves 74 thus resulting in a very compact and efficient arrangement.

The combination of features discussed above has been found to result in a compact efficient swash plate engine which operates readily on vapour of widely varying pressures efficiently. As is obvious to those skilled in the art, the pressure drop across the pump can be varied substantially and desirably passages 72 are somewhat smaller in cross-sectional area than ports 88 which are desirably smaller in area than passage 90. Such sizing faciltates the flow of vapour into and out of engine 10.

Such swash plate engines are well adapted to the generation of mechanical energy from a variety of heat sources, especially relatively low temperature heat sources such as low temperature water streams etc. and may be readily used to generate mechanical energy at remote locations using solar energy etc. An embodiment of the apparatus of the present invention is shown in FIGURE 4. A swash plate engine 10 is shown. Mechanical energy is produced by engine 10 and transmitted via a shaft 20 to a load 100 which could be a pump, generator etc. as known to the art. High pressure vapour flows to engine 10 through a conduit 102 with the exhaust vapour being recovered through a conduit 104.The high pressure vapour is produced in a first heat exchanger 106 where a low-boiling liquid is heated by heat exchange with a heat bearing fluid charged to heat exchanger 106 via a conduit 108 which includes a valve 112 to regulate the flow of fluid into heat exchanger 106 and recovered from heat exchanger 106 via a conduit 110. The high pressure vapour flows through line 102 through a valve 118 to regulate the flow rate and a valve 128 to prevent excessive pressure in the system. Valve 128 is operative to divert high pressure vapour to a storage vessel 130 via a line 122 or to a line 124 via a valve 126 in the event of excessive pressure. Any vapour vented may be recovered by any suitable means such as by condensing the vapour etc.The discharge vapour recovered from engine 10 through line 104 is passed to a second heat exchanger 132 where it is cooled and desirably at least partially condensed by heat exchange with a cooling stream charged to heat exchanger 132 via a line 134 and recovered via a line 136. The resulting low boiling liquid is passed through a line 138 and a pump 140 to storage in storage vessel 130. Liquid is pumped from vessel 1 30 to first heat exchanger 106 through a line 114 which includes a pump 11 6.

In the operation of the apparatus of the present invention high pressure vapour is produced in heat exchanger 106 and passed through line 102 to operate engine 10. A throttle valve 142 is positioned in line 102. A pressure gauge 120 is provided to facilitate the operation of heat exchanger 106 at a rate nearly equal to the vapour requirements of engine 10 with regulation of the vapour flow to engine 10 being regulated by valve 142. Engine 10 operates as described above to drive load 100 with the exhaust gas being collected, condensed and recycled to heat exchanger 106 for use in producing additional high pressure vapour.

A variety of low boiling liquids are suitable for use in the apparatus of the present invention.

Light hydrocarbons such as methane, ethane and propane are considered suitable as are light alcohols and ethers. The low boiling liquids considered most desirable however, are fluorocarbon products such as Freon1.

The particular low boiling liquid used is not considered to constitute a part of the present invention. The selection of a suitable low boiling liquid is within the skill of those in the art in view of the temperature available in the heat bearing stream available for the generation of the high pressure vapour. For instance FREON R-22 has a vapour pressure of about 337 psi at l4O0Fwhich is sufficient pressure to operate engine 1 0. The selection of the low boiling fluid is clearly a function of the heat source available and does not warrant further discussion.

Further a plurality of heat exchange vessels may be used both for the production of the high pressure vapour and the cooling of the exhaust vapour if desired. The use of one or more vessels for such purposes is considered to be known to the art and need not be discussed further except to note that desirably the cooling in heat exchanger 1 32 is sufficient to maintain a desired pressure drop across engine 10.

Having thus described an embodiment of the present group of inventions, it is pointed out that the embodiment shown is illustrative rather than limiting in nature and that many variations and modifications are possible within the scope of the present inventions. It is contemplated that many such variations and modifications may be considered obvious and desirable by those skilled in the art upon a review of the foregoing.

description.

Claims

1. A high pressure vapour driven engine including an engine casing, a cylinder block positioned within said engine casing, a power output shaft rotatably positioned through said cylinder block, a plurality of cylinders provided in said cylinder block with their longitudinal axes substantially parallel to and equally spaced about a longitudinal axis of said power output shaft, a plurality of pistons reciprocally mounted in said cylinders, swash plate means, including a swash plate ring, positioned on said power output shaft, a rod operatively associating each of said pistons with said swash plate ring, injection means for injecting high pressure vapour into each of said cylinders, exhaust means for permitting the escape of vapour from each of said cylinders and control means for controlling the injection and exhaust of said vapour from said cylinders so that said pistons are reciprocated in said cylinders thereby transmitting power to said swash plate via said rods and causing said power output shaft to rotate, wherein there is provided connecting means on each end of each of said rods for rotatably connecting said rods to said pistons and said swash plate ring and stabilising means positioned on said swash plate ring for preventing rotation of said swash plate ring relative to said cylinders.

2. An engine as claimed in claim 1, wherein said injection means, said exhaust means and said control means consist of a compact valve assembly, said valve assembly including a valve over each of said cylinders, said valves being positioned in a plane generally perpendicular to said longitudinal axis of said power output shaft with their inner ends being directed toward said longitudinal axis of said power output shaft, said valve assembly being adapted to receive a central high pressure vapour feed for distribution to each valve and an exhaust discharge receiving means for the recovery of a vapour discharge from each cylinder, said exhaust discharge receiver being positioned generally circumferentially about the outer ends of said valves for collecting said exhaust discharge for recovery through a discharge port.

3. A high pressure vapour driven engine including an engine casing, a cylinder block positioned within said engine casing, a power output shaft rotatably positioned through said cylinder block, a plurality of cylinders provided in said cylinder block with their longitudinal axes substantially parallel to and equally spaced about a longitudinal axis of said power output shaft, a plurality of pistons .ciprncally mounted in said cylinders, swash plate mesns, including a swash plate ring, positioned on said power output shaft.

a rod operatively associating each of said pistons with said swash plate ring, injection means for injecting high pressure vapour into each of said cylinders, exhaust means for permitting the escape of said vapour from each of said cylinders and control means for controlling the injection and exhaust of said vapour from said cylinders so that said pistons are reciprocated in said cylinders thereby transmitting power to said swash plate via said rods and causing said power output shaft to rotate, wherein there is provided a compact valve assembly, said valve assembly including a valve over each of said cylinders, said valves being positioned in a plane generally perpendicular to said longitudinal axis of said power output shaft with their inner ends being directed toward said longitudinal axis of said power output shaft, said valve assembly being adapted to receive a central high pressure vapour feed for distribution to each valve and an exhaust discharge receiving means for the recovery of a vapour discharge from each cylinder, said exhaust discharge receiver being positioned generally circumferentially about the outer ends of said valves for collecting said exhaust discharge for recovery through a discharge port.

4. An engine as claimed in claim 2 or claim 3, wherein each valve consists of a valve bore having its longitudinal axis positioned to intersect said longitudinal axis of said power output shaft and a longitudinal axis of the respective cylinder, said valve bore having a vapour inlet, a vapour outlet and a vapour port fluidly communicating said valve bore and said cylinder, a valve piston, having a suitable opening positioned therethrough slideably positioned in said valve bore and means for reciprocating said valve piston in said valve bore, said valve being adapted alternately to admit high pressure vapour into said cylinder and exhaust vapour from said cylinder to cause said piston to reciprocate and rotate said power output shaft via said swash plate.

5. An engine as claimed in claim 4, wherein said means for reciprocating said valve pistons consists of a cam positioned on said power output shaft and in operative contact with said valve pistons and a biasing means associated with each valve piston for urging said valve pistons toward said cam.

6. An engine as claimed in claim 5, wherein said biasing means are springs.

7. An engine as claimed in claim 1 or 2, or any one of claims 4 to 6 as dependent on claim 2, wherein said stabilising means comprises a substantially rigid member extending generally outwardly from an outer edge of said swash plate ring so that its outer end slideably engages a mating slot adapted to prevent rotation of said swash plate ring relative to said cylinder block.

8. A power plant for converting heat into work comprising an engine as claimed in any one of the preceding claims, a first heat exchanger fluidly communicating said injection means and adapted to heat evaporable fluid at high pressure, a second heat exchanger fluidly communicating said exhaust means to cool said vapour; and a recycle means fluidly communicating said second heat exchanger and said first heat exchanger for recycling said cooled vapour from said second heat exchanger to said first heat exchanger to pressurise the vapour.

9. A high pressure vapour driven engine substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.

1 0. A power plant for converting thermal energy into mechanical energy substantially as hereinbefore described with reference to and as illustrated in the accompanying drawings.