US3200581A

US3200581A - Method, system and apparatus for starting a fluid engine

Info

Publication number: US3200581A
Application number: US222729A
Authority: US
Inventors: Stanley A Weiland
Original assignee: Cleveland Pneumatic Industries Inc
Current assignee: Cleveland Pneumatic Industries Inc
Priority date: 1962-09-10
Filing date: 1962-09-10
Publication date: 1965-08-17
Anticipated expiration: 1982-08-17

Description

7, 1965 s. A. WEILAND 3,200,581

METHOD, SYSTEM AND APPARATUS FOR STARTING A FLUID ENGINE Filed Sept. 10, 1962 INVENTOR.

STANLEY A. WEILAND VNWW ATTORNEY United States Patent 3,2tltl,581 METHQD, SYSTEM AND APFARA'IUS FGR STARTENG A FLUID ENGENE Stanley A. Weiland, Akron, Ohio, assignor to Cleveland Pneumatic Industries Inc., 'Cieveiand, Ohio, at corporation of Ohio Filed Sept. 10, 1962, Ser. No. 222,729 Claims. (Cl. 60-44) This invention relates to fluid type engines wherein a working fluid, such as carbon dioxide, traverses a thermodynamic cycle of high compression, heat, expansion and cooling stages for converting the energy thereof into mechanical work and more particularly to a method, system, arrangement and apparatus for storing a part of the highly compressed working fluid within the system and utilizing the energy of the stored working fluid for re-starting the engine after shut down.

In fluid thermodynamic engines, of the type under consideration, in which the working fluid is under exceedingly high pressures, the problem and task of re-starting the engine, after shut down, heretofore has involved and required the use of heavy and bulky auxiliary equipment, normally in the form of starting motors, or the like, which are required to expend a large amount of external power in eflecting the starting of the engine. Moreover, a source of energy has had to be connected to such auxiliary starting equipment which together with the equipment involves troublesome maintenance problems, increased operating expense, and the like. However, with the use of the method, system, arrangement and apparatus as herein disclosed, described, illustrated, shown and claimed, a fluid type engine, once it has been started, no longer requires the use of auxiliary starting equipment and thus the inconveniences and expense that such equipment imposes on the use of the fluid type engine and system may be eliminated.

It is an object of this invention to provide a system having a fluid type engine containing a working fluid that is alternately highly compressed and expanded together with an arrangement or apparatus for re-starting the fluid type engine after shut down.

It is a further object of the invention to provide a system having a fluid type engine operating under extremely high fluid pressures and containing a working fluid, such as carbon dioxide, together with fluid heating and cooling means or structure, with an arrangement or apparatus interposed between the fluid type engine and the fluid heating means or structure for storing a portion of the working fluid which has been highly compressed while the fluid type engine is operating or running for restarting purposes after shut down of the engine.

It is also an object of the invention to provide, in combination with a system having a fluid type engine for highly compressing a working fluid and separate means or structure for heating and cooling the working fluid, with a controlled accumulator arrangement or apparatus interposed between the fluid type engine and the heating means or structure for re-starting the engine after shut down.

Another object of the invention is the provision, in combination with a closed system having a fluid type engine for highly compressing a working fluid, compensator means or structure for compensating temperature variations of the working fluid and means or structure for heating and cooling the working fluid, of a valved accumulator arrangement or apparatus for storing a quantity of the working fluid after being compressed for subsequent use to re-start the engine.

Still another object of this invention is the provision, in combination with a closed system having a fluid type engine for highly compressing a working fluid, throttlelike control valving for varying the operating speed of the engine, and means or structure for heating and cooling the compressed working fluid, of a valved accumulator arrangement or apparatus for storing a quantity of the working fiuid after being compressed to be utilized as means for re-starting the engine.

It is also another object of this invention to provide an arrangement or apparatus for re-starting a fluid type engine after shut down.

Yet still another object of the invention is the provision of a pressurized fluid storing accumulator arrangement or apparatus connected with a high pressure outlet side of a fluid pressurizing engine for storing a portion of the pressurized fluid for re-starting the engine after it has been stopped.

An additional object of the invention comprises a method of re-starting a high pressure fluid compressing engine by employing the normal fluid compressing function of the engine itself.

Still another additional object of the invention is to provide an improved method of operating a fluid type engine having a working fluid which traverses a thermodynamic cycle of compression, heating, expansion and cooling stages wherein a portion of the working fluid which is compressed by the engine is utilized to start the engine after it has been stopped.

These and other objects and important features of the invention will be apparent from a study of the specification following taken with the drawing, which together show, illustrate, describe and disclose the preferred embodiment or modification of the invention and what is now considered to be the best mode of practicing the principles thereof. Still other embodiments or modifications of the invention may be suggested to those having the benefit of the teaching herein, and all such other embodiments or modifications are intended to be reserved as they fall within the spirit and scope of the subjoined claims.

In the drawing:

The figure is a side elevational view, partly in section, of a schematic showing of a system having a working fluid passing through a thermodynamic cycle and a fluid type engine together with various component structures as well as the improved arrangement or apparatus of this invention associated therewith.

Attention is now directed to the drawing wherein there is illustrated a system 10 comprising a gaseous fluid compressor-type engine 12 which is provided with a block 14 having a counterbored cylinder 16, 16a in which there is mounted reciprocating piston means 18. Attached by bolts or other suitable means to the base of the engine block 14 is a crankcase housing 26 which defines a chamber 24 in which a work output crankshaft 22 is located and connected to the piston means 13 by means of a connecting rod 25. The two sections or" the counterbored cylinder 16, 16a, are each of approximately the same length and are disposed in axial alignment relative to each other, with the smaller diametercd bore 16 being positioned above the larger bore 16a.

The piston means 19 correspondingly shaped to fit the counter'oores 16, 16a of the engine block 14, has an enlarged diametered lower piston portion 23 with an integraily formed smaller diametered piston portion 3t extending generally upwardly therefrom into the cylinder bore 16. Both of the piston portions 23, 3h have suitable piston rings or the like provided for sealingly engag ing the respective cylinder bores 16, 16a. The lower piston portion 28 has an upper annular pressure face 32 disposed in the cylinder bore 36a to form a lower wall of a fluid compression chamber 36 while the upper piston States Letters Patent, Serial Number 2l3,40l filed July 30, 1962, in the name of the instant inventor and assigned 7 to the assignee of the present invention.

The compression chamber 36 has an inlet port or passageway 42 and an outlet port or passageway 44 diametrically positioned in opposedrelationship relative to each other in an upper wall portion of the lower bore 16a of the'engine block 14, with the inlet and the outlet ports or passageways 42; 44 each having suitable control valving 68 and 46 respectively, positioned therein. Suitable conduit means 43 connects the outlet port valving 45 ofthe compression chamber 36 to one end portion of heatingmeans in the form of heat exchanger structure 50 whereat a compressed working fluid P which flows from the compression chamber 36 of the engine 12 is heated to the extent necessary or desired. Disposedintermediate the outlet valving 46 for the compression chamber 36 of the engined and the heat exchanger structure 50there is means in the form of an accumulator arrangement or apparatus which is connected to the conduit means 48 through suitablemanually controlled valving 52. exchanger structure 50 is conduit means 56 which conmeets the heat exchanger structureSft to'the expansion chamber of the engine 12;. Suitable inlet valving 58 is located in an inlet'port or passageway in the upper portion of the expansion chamber 40 to control fluid flow of the heated working fluid F thereto from the heat exchanger structure Sil.

Suitable outlet valving 60, positioned in a manner corresponding to the inlet valving 53, but in an outlet port or passageway, controls the outflow of the workingfluid F from the expansion chamber 40 of the engine 12' into conduit means 62 that is connected to an upper portion of means such as oil separator structure '73. Fluid delivery conduit means 63 also connects the upper portion of the oil separator structure 73 to an inlet end portion of cooling means in the form of heat exchanger structure 64 that functions to cool the working fluid F. Conduit means 66 connects the outlet end of the heat exchanger structure 64 with the inlet port 42 of the compression chamber 36 of the engine 12 through the inlet valving 68. Means such as oil filter structure 74- is connected Connected to the other end portion of the heat able adjustable plunger 84 is slidably mounted in the chamber or bore 82 of the compensator means '75 and plication Scrial'Nurnber 202,285 filed June 13, 1962,

by suitable conduit means 77 between the lower end portion of the oil separator structure 73 and the engine crankcase chamber The specific details of the oil separator structure 73 and the filter structure 7 in combination with the system 10 is more full described, disclosed, illustrated, shown .and claimed in applicants copending application Serial Number 191,075 filed April 30, 1962, now Patent Number 3,138,918, and assigned to the assignee of the present application. 7

To compensate for certain factors, such as temperature variations in the working fluid P which may be caused by variances in the heating eflect created by the heat exchanger structure 50 and the cooling effect of the hen exchanger structure 64, or the substitution of different working fluids in the system 10, there is provided compens'atcr means '75 fixedly mounted on the engine block 14 at a location adjacent the inlet valving 68 and the compression chamber 36. A passageway 10% is provided in the engine block 14 which provides communication between the compression chamber 36 and a chamber or bore 82 within the compensator means 75. A freely movis positionable therein by means of an adjustment to vary the effective volumetric capacity. of the engine com pression chamber 36. For a more detailed and complete disclosure of the compensator means 75 and the function thereof, attentionis directed to applicants copending apassigned to the assignee of the present application.

In using the method, system, arrangement and apparatus as disclosed herein, the working fluid P, such as carbon dioxide, for example, is admitted into the system hrough suitable means, not shown. While not being limited to the valving herein referred to, such yalvingas given being exemplary only and not limiting, a mass of the working fluid F is compressed to a pressure of approximately 6000 psi. and a developed temperature of approximately 300 F. inthe engine compression chamber 36, by the pressurefacellZ of the piston portion 23 on the upstroke of the piston means its by the kinetic energy previously imparted thereto andstored in a conventional flywheel, not shown, secured on the crankshaft 22. As the piston means l8approaches the limit of upward movement the thus highly compressed working fluid F exhausts through the outlet port l l. controlled by the outlet valving 46 and into the conduit means .8. Since manually operable valving'SZ, while the engine 12 is operating, maintains the accumulator 54 in communication with the conduit means 48, as previously described, a portion'or quantity of the highly compressed working fluid F is forced into the accumulator 54, with the remaining compressed portion of the working fluid F passing into the heat exchanger'structure 50 where it is heated to approximately 500 F, with the pressure thereof remaining at substantially 6000 psi.

i As the compressed and heated working fluid F leaves the heat exchanger structure 50 it is conducted by way of the conduit means 56 to the inlet valving 5? of the engine expansion chamber 40, the inlet valving 58 being suitably synchronized in its opening movement with the movement of the piston means 18.with the outlet valving 60 of the expansion chamber 4-50 concurrently remaining closed. As, the compressed and heated working fluidF enters the expansion chamber 40 it immediately expands into a greater volumethereby acting against the face 38 of the piston portion 30, which at this time is in its uppermost position. The pressure of the Working fluid F acting against the upper pressure face 38 of the upper piston portion 30 forces the piston means 18 downwardly to rotate and thereby drive the crankshaft 22 and the flywheel, notshown, associated therewith. As the expansion chamber 49 of the engine 12 enlarges, the Working fluid F therein likewiseexpands whereby the temperature thereof isreduced adiabatically. Upon continned rotation of the crankshaft 22, due to the energy stored in theflywheel attached thereto, the piston means 18 is accordingly forced to move upwardly, the expanded working fluid F in theexpansion chamber 40 escaping the lowered temperature and pressure conditions which exist in the conduit means 62, passes from the oil separater structure 73 into the conduit means 63 and thence into the heat exchanger structure 64 where his further reduced to temperature and pressure'conditions of ap- I proximately 70 F. and 800 "psi. respectively. On leavmg the heat exchanger structure 64 the further cooled working fluid F is conducted to the inlet port or passage- Way 42 of the compression chamber 36 of the engine 12 by the conduit means 66 and the inlet valving 68.

In order to control the speed at which the fluid type engine 12 and the system it operates, throttle-like control means in the form of valving 70 is mounted in the conduit means 62 and connects shunt or by-pass conduit means 72 to the conduit means 66 between the heat exchanger structure 64 and the inlet valving 63 to the compression chamber 36 of the engine 12. For a more detailed and complete disclosure and description of the throttle-like control means '70 for the fluid type engine 12, reference is made to my copending application Serial Number 212,831 filed July 27, 1962, which is also assigned to the assignee of the present application.

Simultaneous with the beginning of the downward expansion stroke of the piston means 18 due to the heated and compressed working fluid F flowing into the expansion chamber 40 of the engine 12 from the heat exchanger structure 50, and the conduit means 56, the inlet valving 68 to the compression chamber 36 of the engine 12 opens to admit the cooled working fluid F to flow from the conduit means 66 whereupon the working cycle of the engine 12 and the system is then repeated.

Prior to stopping or shut down of the engine 12 or the system 10, the manually operable valving 52 which is normally in an open position during the operation of the engine 12 and the system It), is closed or operated to cut off the further admission of the highly pressurized Working fluid F to the accumulator arrangement or apparatus 54 thereby entrapping a quantity or portion of the working fluid F at approximately 6000- p.s.i. within the accumulator 54. Accordingly, when the valving 52 is thereafter moved to an open position the quantity or portion of the high pressurized fluid which has been entrapped within the accumulator 54 will be instantly available for restarting the engine 12.

To re-start the engine 12 after shut down, assuming the heat exchanger structures St and 64 have been conditioned to normally function as previously described, the throttle-type control means 76 is actuated to open the conduit means 62 for fluid flow of the working fluid F and the accumulator cut-off valving 52 is then actuated to open the accumulator 54 to the conduit means 455. Instantly, the quantity or portion of the highly pressurized working fluid F at approximately 6000 p.s.i. confined within the accumulator arrangement or apparatus 54 then flows through the heat exchanger structure 59, the conduit means 56 and the inlet valving 58 to the engine expansion chamber 40 to drive the piston means 18 downwardly and thereby cause the engine 12 and the system 10 to again function in the manner above described.

While the invention has been described, disclosed, illustrated and shown in terms of the preferred embodiment or modification which it has assumed in practice, the scope of the invention should not be deemed to be limited by the precise preferred embodiment or modification as herein described, disclosed, illust-rated and shown, since other embodiments and modifications are intended to be reserved where they fall within the scope of the claims herein appended.

I claim as my invention:

1. In a system having a Working fluid traversing a thermodynamic cycle of compression, heating, expansion and cooling stages,

a fluid engine provided with a working fluid compres sion chamber and a Working fluid expansion chamber,

valved inlet and outlet passageways opening to each of said chambers,

conduit means connecting the inlet passageways of said chambers to the outlet passageways thereof,

piston means operable in said chambers and connected for rotating a working output shaft,

heating means associated with the conduit means that extends from said compression chamber outlet passageway,

cooling means associated with the conduit means which extends to the compression chamber inlet passagethrottle-like means for controlling the operation and speed of the engine by variably bypassing the working fluid by the cooling means,

compensator means for varying the volume of the compression chamber of the engine to compensate for variations in temperature and different working fluids,

an accumulator connected to the conduit means which extends from the compression chamber outlet passageway, said accumulator being disposed at a location which is intermediate the compression chamber of the engine and the heating means for receiving and storing a quantity of compressed working fluid therein, and

valving for controlling the flow of high pressure working fluid to and from the accumulator, said valving normally being in an open position during the operation of the engine and closed prior to the shut down thereof to entrap the quantity of high pressure working fluid in the accumulator and operable to the open position to enable such entrapped high pressure working fluid to be utilized to restart the engine.

2. In a system having a working fluid traversing a thermodynamic cycle of compression, heating, expansion and cooling stages,

a fluid engine provided with a working fluid compression chamber and a working fluid expansion chamber,

conduit means for connecting the compression and the expansion chambers of the engine together,

heating means associated with the conduit means and disposed therealong at a location which is intermediate the chambers,

throttle-like means for controlling the operation and speed of the engine by variably bypassing the working fluid by the cooling stage of the system,

an accumulator connected to the conduit means and disposed at a location therealong which is intermediate the compression chamber of the engine and the the heatin means for receiving and storing a quantity of compressed working fluid therein, and

valving for controlling the flow of high pressure working fluid to and from the accumulator, said valving normally being in an open position during the operation of the engine and closed prior to the shutdown thereof to entrap the quantity of high pressure work ing fluid in the accumulator and operable to the open position to enable such entrapped high pressure working fluid to be utilized to restart the engine.

3:. In a system having a working fluid traversing a thermodynamic cycle of compression, heating, expansion and cooling stages,

conduit means for connecting the chambers of the engine together,

heating means associated with the conduit means for heating such working fluid,

means for controlling the operation and speed of the engine by variably bypassing the working fluid by the cooling stage of the system,

means for varying the volume of the compression cham ber of the engine to compensate for temperature variations and different working fluids, and

apparatus for re-starting the engine after shut down,

said apparatus comprising,

an arrangement connected to the conduit means at a location therealong which is between the compresthermodynamic cycle of compression, heating, expansion and cooling stages, said engine comprising a compression chamber and an expansion chamber,

valved inlet and outlet conduit means connecting the compression and expansion chambers together,

piston means operable in said chambers,

heating means connected to the outlet conduit means of the compression chamber,

cooling means connected to the inlet conduit means of the compression chamber,

throttle means for controlling the operational speed of the engine by variably by-passing the working fluid by the cooling means,

compensator means for varying the volume of the compression chamber to compensate for variations in temperature and different working fluids,

an accumulator connected to the outlet conduit means of the compression chamber, said accumulator being disposed at a location which is intermediate the compression chamber of the engine and the heating means for receiving and storing a quantity of compressed working fluid therein, and

valving for controlling the flow of high pressure Working fluid to and from the accumulator, said valving normally being in an open position during the operation of the engine and closed prior to the shut down thereof to entrap the quantity of high pressure working flu-id in the accumulator and operable to the open position to enable such entrapped high pressure fluid to be utilized to restart the engine.

5. A fluid engine having a working fluid traversing a thermodynamic cycle of compression, heating, expansion and cooling stages, said engine comprising a compression chamber and an expansion chamber,

piston means operable in said chambers,

heating means connected to the outletconduit means of the compression chamber,

cooling means connected to the inlet conduit means of the compression chamber,

compensator means for varying the volume of the compression chamber to compensate for variations in temperature and different working fluids, and

an arrangement connected to the outlet conduit means of the compression chamber at a location therealong which is intermediate the compression chamber and the heating means for receiving and storing a quantity of compressed working fluid therein during the operation of the engine and for releasing the quantity of high pressure Working fluid after shut down of the engine to enable the quantity of high pressure Working fluid to be utilized to re-start theiengine.

6. A fluid engine having a working fluid traversing a thermodynamic cycle of compression, heating, expansion and cooling stages, said engine comprising a compression chamber and an expansion chamber,

inlet and outlet conduit means connecting the com pression and expansion chambers together,

piston means operable in said chambers,

heating means connected to the outlet conduit means of the compression chamber,

cooling means connected to the inlet conduit means of the compression chamber,

7 throttle means for controlling the operational speed of r 8 a the engine by variably by-passing the working fluid by the cooling means, and w an arrangement connected to the outlet conduit means of the compression chamber at a location therealong which is intermediate the compression chamber and the heating means for receiving and storing a quantity of compressed working fluid therein during the operation of the engine and for releasing the quantity of high pressure working fluid after shut down of the engine to enable the quantity of high pressure working fluid to be utilized to re-start the engine.

7. A fluid engine having a working fluid traversing a thermodynamic cycle of compression, heating, expansion and cooling stages, said engine comprising a compression chamber and an expansion chamber,

inlet and outlet conduit means connecting the compression and expansion chambers together,

piston means operable in said chambers, I g

heating means connected'to the outlet conduit means of the compression chamber,

compensator means for varying the volume of the compression chamber to compensate for variations in 7 temperature and iditferent Working fluids, and

an arrangement connected to the outlet conduit means of the compression chamber, at a location therealong which is intermediate the compression chamber and the heating means for receiving and storing a quantity of compressed working fluid therein during the operation of the engine'and for releasing the quantity of high pressure Working fluid afterrshut down of the engine to enable the quantity of high pressure Working fluid to be utilized to re-start the engine. 8. A method of operating a fluid engine having a working fluid which traverses a thermodynamic cycle of compression, heating, expansion and cooling stages wherein the engine is provided with fluid compression and expansion chambers having piston means operable therein to rotate a Work output shaft,

said method comprising the steps of highly compressing such working fluid in the compression chamber of the engine, heating the highly compressed Working fluid, expanding the highly compressed and heated working fluid in the expansion chamber'of the engine, cooling the working fluid after the expansion thereof, selectively variably by-passing the cooling stage of the working fluid to vary-the operational speed of the engine, again highly compressing the working fluid in the compression chamber of the engine after theexpansion thereof, varying the volume of the fluid compression chamber of the engine during the compression of the working fluid to compensate for any variations in the temperature and diflerent properties of working fluids, confining and storing a quantity of the highly compressed Working fluid While theengine is operating, and thereafter on shut down of the'engine releasing the stored quantity of the highly compressed working fluid and utilizing same to re-start the engine, 9. A method of operating a fluid engine charged with a working fluid which traverses a thermodynamic cycle of compression, heating, expansion and cooling stages wherein the engine is provided with fluid compression and expansion chambers having piston means operable therein to rotate a Work output shaft, said method comprising the steps of highly compressing such working fluid in the corn- I pression chamber of the engine, heating the highly compressed working fluid, expanding the highly compressed and heated working fluid in the expansion chamber of the engine, cooling the working fluid after the expansion thereof, selectively variably by-passing the cooling'stage of the 9 working fluid to vary the operational speed of the engine, again highly compressing the working fluid in the compression chamber of the engine after the expansion thereof, confining and storing a quantity of the compressed working fluid while the engine is operating, and thereafter on shut down of the engine releasing the stored quantity of compressed working fluid and utilizing same to re-start the engine. 10. A method of operating a fluid engine charged with a working fluid which traverses a thermodynamic cycle of compression, heating, expansion and cooling stages, wherein the engine is provided with fluid compression and expansion chambers having piston means operable therein to rotate a work output shaft,

said method comprising the steps of highly compressing such working fluid in the compression chamber of the engine, heating the highly compressed working fluid, expanding the highly compressed and heated working fluid in the expansion chamber of the engine, cooling the working fluid after the expansion thereof, again highly compressing the working fluid in the compression chamber of the engine after the expansion thereof,

varying the volume of the fluid compression chamber of the engine during the compression of the working fluid to compensate for any variations in the temperature and diflerent properties of working fluids,

confining and storing a quantity of the compressed Working fluid while the engine is operating, and

thereafter on shut down of the engine releasing the stored quantity of compressed working fluid and utilizing same to re-start the engine.

References Cited by the Examiner UNITED STATES PATENTS 324,060 8/85 Woodbury et a1 24 459,501 9/91 Ventzki 6024 1,879,563 9/32 Smith 6024 1,895,082 1/33 Montero 6024 2,067,453 1/37 Lee 6024 X 2,602,288 7/52 Rinia et al. 6024 2,643,508 6/53 Clay et al. 6024 2,746,241 5/56 Dros et a1. 6024 3,009,315 11/61 Drumm 6024 JULIUS E. WEST, Primary Examiner.

ROBERT R. BUNEVICH, Examiner.

Claims

3. IN A SYSTEM HAVING A WORKING FLUID TRAVERSING A THERMODYNAMIC OF COMPRESSION, HEATING, EXPANSION AND COOLING STAGES, A FLUID ENGINE PROVIDED WITH A WORKING FLUID COMPRESSION CHAMBER AND A WORKING FLUID EXPANSION CHAMBER, CONDUIT MEANS FOR CONNECTING THE CHAMBERS OF THE ENGINE TOGETHER, HEATING MEANS ASSOCIATED WITH THE CONDUIT MEANS FOR HEATING SUCH WORKING FLUID, MEANS FOR CONTROLLING THE OPERATION AND SPEED OF THE ENGINE BY VARIABLY BYPASSING THE WORKING FLUID BY THE COOLING STAGE OF THE SYSTEM, MEANS FOR VARYING THE VOLUME OF THE COMPRESSIN CHAMBER OF THEENGINE TO COMPENSATE FOR TEMPERATURE VARIATIONS AND DIFFERENT WORKING FLUIDS, AND APPARATUS FOR RE-STARTING THE ENGINE AFTER SHUT DOWN, SAID APPARATUS COMPRISING, AN ARRANGEMENT CONNECTED TO THE CIRCUIT MEANS AT A LOCATION THEREALONG WHICH IS BETWEEN THE COMPRESSION CHAMBER OF THE ENGINE AND THE HEATING MEANS FOR RECEIVING AND STORING A QUANTITY OF COMPRESSED WORKING FLUID WHILE THE ENGINE IS RUNNING AND FOR RELEASING THE QUANTITY OF STORED COMPRESSED WORKING FLUID AFTER THE ENGINE HAS BEEN STOPPED TO RE-START THE ENGINE.