EP0165927A1

EP0165927A1 - Compression relief

Info

Publication number: EP0165927A1
Application number: EP19840901167
Authority: EP
Inventors: Randall B. Blum
Original assignee: Caterpillar Tractor Co
Current assignee: Caterpillar Inc
Priority date: 1983-12-27
Filing date: 1984-02-21
Publication date: 1986-01-02
Also published as: WO1985002893A1

Abstract

Des soupapes de décompression sont connectées aux chambres de compression de moteur et de compresseur. L'addition d'une caractéristique de décharge manuelle aux soupapes de décompression automatiques connues en augmente la complexité et requiert de grands efforts manuels pour combattre la force de ressort automatique élevée. La présente soupape de décompression comporte une soupape de sûreté automatique (74) activée par un excédent de pression à l'intérieur de la chambre de compression (12) et une soupape de sûreté manuelle (90) actionnée indépendamment de la soupape de sûreté automatique (74). La soupape automatique (74) décharge l'excédent de pression régnant dans la chambre (12) lorsque la pression de la chambre (12) dépasse la force élevée du ressort (88), déplaçant l'élément de soupape (76, 134) de son siège (42) et permettant à l'excédent de pression de pénétrer dans un trou (44) pratiqué dans le corps et de s'échapper dans un passage radial (46), une chambre annulaire (40) et un passage (24) jusqu'à l'atmosphère. La soupape manuelle (90) est actionnée par le déplacement manuel d'une poignée (112) en réponse à un ressort à force faible (122) jusqu'à une position ouverte. En position ouverte, la chambre (12) est ventilée par des passages (50, 94, 96) ou par un passage (132, 138) pénétrant dans une chambre annulaire (40) et sortant par un passage (24) allant vers l'atmosphère. La poignée (112) peut également être tournée et verrouillée en position ouverte. La chambre (12) est ainsi déchargée de l'excédent de pression dépassant un niveau prédéterminé par la soupape automatique (74) et est ventilée de manière sélective au moyen de la soupape manuelle (90). La présente soupape de décompression offre une soupape de sûreté manuelle (90) dont l'actionnement nécessite peu d'effort et une soupape de sûreté automatique (74) pour décharger l'excédent de pression d'une chambre (12). La soupape manuelle (90) et la soupape automatique (74) sont coaxiales afin de diminuer la complexité de la soupape de décompression.Pressure relief valves are connected to the engine and compressor compression chambers. The addition of a manual discharge characteristic to known automatic pressure relief valves increases its complexity and requires great manual effort to combat the high automatic spring force. The present pressure relief valve comprises an automatic safety valve (74) activated by an excess of pressure inside the compression chamber (12) and a manual safety valve (90) actuated independently of the automatic safety valve ( 74). The automatic valve (74) discharges the excess pressure prevailing in the chamber (12) when the pressure in the chamber (12) exceeds the high force of the spring (88), moving the valve element (76, 134) by its seat (42) and allowing the excess pressure to enter a hole (44) made in the body and to escape in a radial passage (46), an annular chamber (40) and a passage (24) up to the atmosphere. The manual valve (90) is actuated by manually moving a handle (112) in response to a weak force spring (122) to an open position. In the open position, the chamber (12) is ventilated by passages (50, 94, 96) or by a passage (132, 138) penetrating into an annular chamber (40) and leaving by a passage (24) going towards the atmosphere. The handle (112) can also be turned and locked in the open position. The chamber (12) is thus relieved of excess pressure exceeding a predetermined level by the automatic valve (74) and is selectively ventilated by means of the manual valve (90). The present pressure relief valve provides a manual safety valve (90) which requires little effort to operate and an automatic safety valve (74) for discharging excess pressure from a chamber (12). The manual valve (90) and the automatic valve (74) are coaxial to decrease the complexity of the pressure relief valve.

Description

Compression Relief

Technical Field

This invention relates generally to relief valves and more particularly to relief valves adapted to be connected to a compression chamber.

Background Art

The pressure within a chamber/ such as the combustion chamber of an engine or the compression chamber of an air compressor/ can exceed the structural limit of the component parts causing malfunction or failure of the engine or compressor. For example/ in a two or four cycle engine as the piston moves during its intake stroke/ the intake valve or valves open and air enters the combustion chamber. If a carburetor is•used with the engine/ the air entering the combustion chamber is rich with fuel. Near the top of the compression stroke a spark is discharged and the mixture is exploded. If the engine is fuel injected/ the air as drawn into the cylinder does not contain fuel. However/ near the top of the compression stroke fuel is injected into the combustion chamber and the mixture of fuel and air explodes. The heat created by compressing the air to such a high ratio enables the explosion to occur in a diesel engine. Similar conditions occur within the chamber of an air compressor. The primary difference between the engine and the compressor is that the compressor uses no fuel nor does an explosion occur. Variable condition of speed, air and fuel can cause the pressure resulting within the chamber to exceed the structural integrity of the materials used in constructing the engine or compressor components.

OMPI Relief valves are used to vent excess pressures from such chambers. The Marine Society requires that compression relief valves be provided on Marine engines having a bore of 230 mm 19.06 inches) or larger. Several types of relief valves well known in the art have been employed to vent pressure from a compression chamber. Examples of such relief valves are disclosed in the following U.S. Patent Nos. 2,911,999 issued November 10, 1959 to John Lamb; 1,959,278 issued May 15, 1934 to Stearns? and 2,517,562 issued August 8, 1950 to Hanson.

While the relief valves of each of the foregoing patents provide for a discharge of an accumulative pressure each pose operational problems limiting their prospective uses.

Typically, the prior art utilizes either a manual or automatic relief mechanism. Such mechanisms are normally not incorporated to serve both functions. Of those which have been incorporated to serve both functions the manual mechanism must overcome the activation force of the automatic mechanism before the manual relief can be actuated. When adapting these relief valves for use with a compression chamber, the force required to overcome the automatic relief mechanism is quite high and difficult to obtain manually. For example, the pressure within a compression chamber of an engine can be between 13,000 and 20,700 kPa (1/885 and 3,002 psi). To overcome this pressure manually, some type of mechanical advantage must be provided. The mechanical mechanism to produce this advantage adds to the complexity, size and cost of the valve. The mechanism also provides additional components which can fail or malfunction.

Usually, but not always, the manually activated compression relief valve is operated in conjunction with several cylinders or several co pression chambers. The mechanism cannot be used if the relief valve is to be utilized as an assist for starting the engine a single cylinder at a time.

Although some of these relief valves have capabilities for varying the pressure at which relief occurs, many times, the adjusting mechanism will not remain fixed to the desired setting or fixed position during the assembly of the valve within the engine or compressor because the locking mechanism malfunctions. The present invention is directed to overcoming one or more of the problems as set forth above.

Disclosure of the Invention In one aspect of the present invention, a relief valve is adapted to be connected to a compression chamber of an engine or air compressor. The relief valve is comprised of a cylindrical body, a means for automatically releasing a pressure from the compression chamber and a manual means for releasing a pressure from the compression chamber. The means for automatically releasing a pressure from the chamber is positioned partially within the cylindrical body. The means for manually releasing a pressure from the compression chamber independently of the automatic actuated means is also positioned partially within the cylindrical body.

Furthermore, the invention incorporates both a manually and automatically activated relief valve, of which the manual actuated means of the valve is not required to overcome the force of the automatically actuated means of the valve to relieve pressure. Additionally, the manual actuated means of the valve can be utilized to aid in the starting of an engine since it is adapted for independent use with each

OMFI individual chamber. In addition to these improvements, the compression relief valve has also been constructed to hold the relief valve to a fixed setting during the assembly of the valve to the chamber.

Brief Description of the Drawing

Figure 1 is a longitudinal sectional view of the compression relief valve connected to a compression chamber. Figure 2 is a longitudinal sectional view of a second embodiment of the compression relief valve connected to a compression chamber.

Figure 3 is a top diagrammatic view of an engine showing the compression relief valve connected to the engine.

For illustrative convenience, the figures are shown with the compression relief valve rotated out of the normal plane as functionally connected to the compression chamber. By rotating the valve and eliminating other components associated with the compression chamber, the drawings were simplifed enabling the invention to be more easily viewed. Other components associated with the compression chamber - intake valves, exhaust valves, springs, injection nozzles, etc. - will determine the location and rotation of the compression relief valve relative to the compression chamber when used in conjunction with an engine or compressor.

Best Mode for Carrying Out the Invention

As shown in Figure 3, a compression relief valve 10 is connected to a compression chamber 12 partially defined by a cylinder head 14 of an engine or compressor. Figures 1 and 2 further disclosure that the cylinder head 14 has a bore 16 connected to the compression chamber 12. The bore 16 has an annular shoulder 18 adjacent the compression chamber 12 and a threaded portion 20 at its open end 22. A passage 24 is connected to the bore 16 and is open to the atmosphere.

A cylindrical body 26 is partially disposed in the bore 16 of the cylinder head 14. The cylindrical body 26 has a first end 28, a second end 30, a " peripheral surface 32 intermediate the first and second ends 28,30 and an externally threaded portion 34 located on the peripheral surface 32 intermediate the first and second ends 28,30. The externally threaded portion 34 engages with the threaded portion 20 of the bore 16 in the cylinder head 14 and a sealing surface 36 at the first end 28 of the body 26 contacts the annular shoulder 18. An annular groove 38 is located in the peripheral surface 32 intermediate the first and second ends 28,30 forming an annular chamber 40 between the body 26 and the bore 16 in the cylinder head 14. A conical seat 42 is disposed intermediate the first and second ends 28,30 of the body 26. A bore 44 extends from the seat 42 to the second end 30 and a radial passage 46 leads from the bore 44 to the annular groove 38. An internally threaded portion 48 of the bore 44 is located near the second end 30 of the body 26. A passage 50 extends from the seat 42 to the first end 28. A threaded hole 52 near the second end 30 of the body 26 extends from the peripheral surface 32 to the bore 44. An adjusting nut 54 is partially positioned within the bore 44 of the cylindrical body 26. The nut 54 has a first end 56, a second end 58 and a bore 60 extending from the first to the second ends 56,58. An externally threaded portion 62 of the nut 54 is located near the second end 58 and engages with the internally threaded portion 48 of the cylindrical body 26. A plurality of flat surfaces, one shown at 64, are located near the second end 58 of the adjusting nut 54. A first notch 66 and a second notch 68 are located at the first end 56 of the nut 54. The second notch 68 is indexed 90° from the first notch 66.

A means 70 is provided for securing the adjusting nut 54 to the cylindrical body 26 in a fixed position. The securing means 70 includes the threaded hole 52 of the body 26, one of the flat surfaces 64 of the nut 54, and a lock screw 72 in the threaded hole 52. The lock screw 72 is adapted to engage one of the flat surfaces 64 providing the fixed position of the adjusting nut 54 relative to the cylindrical body 26. A means 74 is provided for automatically releasing a pressure from the compression chamber 12. The automatic means 74 is positioned partially within the bore 44 of the cylindrical body 26. The automatic means 74 includes the annular groove 38, the radial passage 46 leading from the bore 44 to the annular groove 38 and a sealing valve element 76 positioned in the bore 44. The valve element 76 has a sealing end 78 and an end 80 opposite the sealing end. A means 82 for biasing the valve element 76 contacts the opposite end 80 and forces the sealing end 78 into contact with the seat 42 establishing a closed position which blocks the communication of flow through the passage 50. The valve element 76 is movable to an open position at which communication is established through the passage 50 to the bore 44 and pressure is released from the compression chamber 12.

The biasing means 82 includes the adjusting nut 54, and a compression coiled spring 88 positioned between the valve element 76 and the first end 56 of the nut 54. Alternatively other types of springs such as a series of Belleville washers could be substituted for the compression spring. The adjusting nut 54 is adapted to selectively adjust a load applied to the compression spring 88. A means 90 is provided for manually releasing a pressure from the compression chamber 12 independently of the automatic releasing means 74. The manual means is partially positioned within the bore 44 of the cylindrical body 26 and the bore 60 of the adjusting nut 54. The manual means 90 includes the sealing valve element 76. The valve element 76 is hollow and has a seat 92 intermediate the sealing end 78 and the opposite end 80/ a passage 94 connecting the seat 92 with the sealing end, a passage 96 connecting the seat 92 with the opposite end 80, and a valve 98 having a sealing surface 100 adapted to contact the seat 92. The valve 98 is movable between a closed position at which communication through the passage 96 is blocked, and an open position at which communication is established through the passage 96 to the bore 44.

A means 106 for manually actuating the manual releasing means 90 between the closed and open positions is also part of the manual releasing means 90.

The automatic releasing means 74 and the manual releasing means 90 are coaxially positioned partially within the bore 44 of the cylindrical body 26. The actuating means 106 includes a stem 108 extending from the sealing surface 100 of the valve 98 and extending through the passage 96, the bore 44 of the cylindrical body 26 and the bore 60 of the nut 54. The stem 108 has a threaded end 110 located at the end opposite the sealing surface. A handle 112 is threadably connected to the threaded end of the stem 108. A lock nut 110 prevents the handle 112 from turning on the stem 108. Alternatively the handle 112

OMFI could be attached to the stem 108 by a set screw or any other method which would prevent the handle 112 from rotating on the stem 108.

A means 118 for biasing the valve 98 to its closed position and a means 120 for retaining the manual releasing means 90 in the open position are included as part of the manual releasing means 106.

The biasing means 118 includes a compression coiled spring 122 positioned around the stem 108 between the second end 58 of the adjusting nut 54 and the lock nut 116. Alternatively a series of Belleville washers could be substituted for the compression spring. The retaining means 120 includes the first and second notches 66,68 of the adjusting nut 54 and a protrusion 124 extending radially from the stem 108 intermediate the sealing surface 100 and the threaded end 110. The protrusion 124 is seated within the first notch 66 in the open position and freely positioned within the second notch 68 in the closed position 102. The depth of the first notch 66 is selected to hold the protrusion 124 therein thereby retaining the valve 98 in the open position 104.

The second notch 68 is of a selected depth to allow the sealing surface 100 to contact the seat 92 placing the valve 98 in the closed position.

An alternate embodiment of a compression relief valve of the present invention is disclosed in Figure 2. It is noted that the same reference numerals of the first embodiment are used to designate similarly constructed counterpart elements of this embodiment. In this embodiment, however, the seat 42 is a flat annular surface and a plurality of passages 128 extend from the seat 42 to the first end 28 of the cylindrical body 26, conical seat 130 is located at the first end 28 of the body 26 and a passage 132 extends from the seat 128 to the bore 44. An annular shaped sealing valve element 134 is positioned in the bore 44. The element 134 has a sealing surface 136 and a passage 138 therein. The spring 88 of the biasing means 82 biases the element 134 to sealing contact with the seat 42 blocking communication through the plurality of passages 128 in the closed position. The element 134 is movable to the open position wherein communication is established through the passages 128. The manual means 90 now includes the passage

138, the seat 130 and the passage 132 in addition to those elements described earlier. The valve 98 extends through the passage 132 and the sealing surface 100 is adapted to contact the seat 130 blocking communication through the passage 132 in the closed position and is movable to the open position wherein the communiction is established through passage 132 and passage 138. The biasing means 118 now biases the sealing surface 100 into contact with the seat 130.

Industrial Applicability

The compression relief valve 10 is attached to the compression chamber 12 as illustrated in the drawings. The valve 10 is used to relieve pressure from the compression chamber 12 by either the automatic releasing valve means 74 or the manual releasing valve means 90.

The automatic releasing valve means 74 is activated when the pressure within the compression chamber 12 exceeds the predetermined load set on the valve element 76 by the spring 88. When the pressure within the compression chamber 12 exceeds the predetermined force, the valve element 76 is moved to the open position, and the excess pressure is relieved from the compression chamber 12 through the passage 50

r _O PI in the body 26, the bore 44, the radial passage 46, the annular chamber 40 and the passage 24 to the atmosphere. After the excessive pressure has been relieved_/ the compression spring 88 will force the valve element 76 into sealing contact with the seat 42 thereby establishing the closed position.

The automatic releasing valve means 74 is adjustable to determine the pressure at which relief from the compression chamber 12 occurs. By rotating the adjusting nut 54 into the body 26 further compression of the spring 88 places a greater force on the valve element 76. By rotating the adjusting nut 54 so as to remove the nut 54 from the body 26/ the force is reduced. When the desired force has been applied to the valve element 76 the lock screw 116 is threaded into the threaded hole 52 and contacts the flat surface 64 in a forced relationship preventing the nut 54 from rotating within the body 26. The automatic releasing valve means 74 can be used with a variety of engine and compressor configurations. For example in an engine having a low compression ratio/ the maximum allowable pressure within the compression chamber 12 would be approximately 13,000 kPa. The automatic releasing valve means 74 is adjusted to open at a pressure slightly above 13/000 kPa. Should the pressure within the compression chamber 12 exceed the adjusted load, the valve means 74 will vent the excessive pressure as described above to the atmosphere. The same valve means 74 can be used for an engine or compressor having a high compression ratio by following the steps as described above to increase the force required to unseat the valve element 76 from the seat 42.

The manual releasing valve means 90 can be used to manually relieve the pressure in the compression chamber 12. In use, the handle 112 of the anual releasing valve 90 is depressed against the spring 122 moving the valve 98 from the closed position to the open position. The handle 112 is rotated approximately 90° and released causing the protrusion 124 to be retained in the first notch 66 thereby holding the valve 98 in the open position. Any pressure within the compression chamber 12 is relieved through passage 50 in the body 26, passage 94,96 in the valve element 76, bore 44 in the body 26, radial passage 46 in the body 26, annular chamber 40 and passage 24 to the atmosphere.

The valve 10 is adapted to be used with each of the compression chambers 12 of a multi-cylinder engine. The manual releasing valve means 90 is operative independently of the automatic releasing valve means 74. The valve means 90 is also biased into sealing contact by the compression pressure within the compression chamber 12.

The manual releasing valve means can be used to aid the starting of an engine. For example, the valve means 90 are moved to and retained in the open position and the engine crankshaft rotated. The valves 90 are rotated into the closed position in a sequential order to start the engine. The manual releasing valve 90 can also be beneficial as a service tool. For example, should an engine or compressor become "locked-up" due to a noncompressible fluid filling the compression chamber 12 such as caused by a leaking head gasket. The manual releasing valve 90 is moved to and retained in the open position and the crankshaft is rotated. The noncompressible fluid follows the path to the atmosphere as described earlier and allows the engine to be rotated. The compression chamber 12 requiring service can be pinpointed because the fluid exits

r Q Pi passage 24 of the respective chamber. After the fluid has been removed from the compression chamber 12, the engine can be repaired or started if so desired.

The manual releasing valve 90 is not required to overcome the force of the automatic releasing valve means 74 to relieve pressure from the compression chamber 12. The valve means 90 uses a small spring force to hold the sealing surface 100 against the seat 92 thereby resulting in a minimum effort to move the valve means 90 between the open and closed positions. In the operation of the embodiment of the invention as shown in Figure 2 the automatic releasing valve means 74 is activated substantially as described earlier, however? the pressure within the chamber 12 exerts the excess pressure through passages 128 on valve element 134 to overcome the force of the spring 88 and move the element 134 into its open position. In the open position, the excess pressure is relieved from the compression chamber 12 through the passages 128 in the body 26, the passage 138 in the valve element 134 and into the bore 44. The manual releasing valve means 90 is operated substantially as described earlier, however? the flow path is somewhat different. For example, after the valve 98 is opened the pressure within the chamber 12 flows through passages 132,138 in the body 26 and element 134 respectively into the bore 44.

Other aspects, objects and advantages of this invention can be obtained from a study of the drawing_/ the disclosure and the appended claims.

' C ^*TI

Claims

1. A compression relief valve (10) adapted to be connected to a compression chamber (12) comprising: a cylindrical body (26) having a first end

(28), a second end (30), a seat (42) intermediate the first and second ends (28,30), a passage (50,128) extending from the seat (42) to the first end (28) and a bore (44) extending from the seat (42) to the second 0 end (30) ; means (74) for automatically releasing a pressure from the compression chamber (12) , said automatic releasing means (74) being partially positioned within the bore (44) of the cylindrical body 5 (26) ? and means (90) for manually releasing a pressure from the .compression chamber (12) independently of the automatic releasing means (74) , said manual means (90) being partially positioned within the bore (44) of the o cylindrical body (26) .

2. The valve as claimed in claim 1, wherein said cylindrical body (26) has a peripheral surface (32) intermediate the first and second ends (28/30) 5 thereof, an annular groove (38) in the peripheral surface (32) , and a radial passage (46) leading from the bore (44) to the annular groove.

3. The valve as claimed in claim 2, further including an adjusting nut (54) having a first end

(56), a second end (58) and a bore (60) extending from the first to the second ends (56,58).

5

OMPI 4. The valve as claimed in claim 3, wherein said automatic releasing means (78) includes a passage (50,128) extending from the seat (42) to the first end (28) of the cylindrical body (26), a valve element (76,134) positioned in the bore (44) and adapted to contact the seat (42) , and means (82) for biasing the valve element (76,134) into contact with the seat (42).

5. The valve as claimed in claim 4, wherein said valve element biasing means (82) includes a compression spring (88) positioned between the valve element (76,134) and the first end (56) of the adjusting nut (54) .

6. The valve as claimed in claim 3 wherein said manual releasing means (90) includes a hollow sealing valve element (76) positioned in the bore (44) near the first end (28) of the cylindrical body (26) said sealing valve element (76) having a sealing end (78), an opposite end (80), a seat (92) intermediate the sealing end (78) and the opposite end 80) , a passage (96) connecting the seat (92) with the opposite end (80) and a passage (94) connecting the seat (92) with the sealing end (78) ? a valve (98) having a sealing surface (100) adapted to contact the seat (92) and being movable between a closed position at which communication through the passage (96) is blocked and an open position at which communication is established through the passage (96) ? and means (106) for manually actuating the valve (98) between the closed and open positions. 7. The valve as claimed in claim 6, wherein said manual actuating means (106) includes a stem (108) extending from the sealing surface (100) through the passage (96) and the bore (44) of the cylindrical body (26), a handle (112) connected to the stem (108) at an end opposite the sealing surface (100) , means 1118) for biasing the sealing surface (100) into contact with the seat (92) , and means (120) for selectively retaining the manual releasing means (90) in the open position.

8. The valve as claimed in claim 7, wherein said retaining means (120) includes a first notch (66) at the first end (56) of the adjusting nut (54) , a second notch (68) at the first end (56) of the adjusting nut (54) , and a protrusion (124) extending radially from the stem (108) intermediate the sealing surface (100) and the handle (112) , said protrusion (124) being seated within the first notch (66) of the adjusting nut (54) in the open position and being freely positioned within the second notch (68) in the closed position.

9. The valve as claimed in claim 7, wherein said sealing surface biasing means (118) of the manual actuating means (106) includes a compression spring (122) positioned between the second end (58) of the adjusting nut (54) and the handle (112).

10. The valve as claimed in claim 3, wherein said manual releasing means (90) includes a seat (130) at the first end (28) of the cylindrical body (26), a passage (132) extending from the seat (130) to the bore (44) of the cylindrical body (26), a valve (98) having a sealing surface (100) adapted to contact the seat (130) and being movable between a closed position at which communication through the passage (132) is blocked and an open position at which communication is established through the passage (132), and means (106) for manually actuating the valve (98) between the closed and open positions.

11. The valve as claimed in claim 10, wherein said manual actuating means (106) includes a stem (108) extending from the sealing surface (100) through the passage (132) and the bore (44) of the cylindrical body (26) , a handle (112) connected to the stem (108) at an end opposite the sealing surface (100) , means (118) for biasing the sealing surface (100) into contact with the seat (92) , and means (120) for selectively retaining the manual releasing means (90) in the open position.

12. The valve as claimed in claim 11, wherein said retaining means (120) includes a first notch (66) at the first end (56) of the adjusting nut (54) , a second notch (68) at the first end (56) of the adjusting nut (54) , and a protrustion (124) extending radially from the stem (108) intermediate the sealing surface (100) and the handle (112) , said protrusion

(124) being seated within the first notch (66) of the adjusting nut (54) in the open position and being freely positioned within the second notch (68) in the closed position.

GMPI 13. The valve as claimed in claim 3, including a means (70) for securing the adjusting nut to the cylindrical body (26) in a fixed position.

14. A valve as claimed in claim 13, wherein said securing means (70) includes a threaded hole (52) in the cylindrical body (26) , a flat surface (64) on the adjusting nut (54), and a lock screw (72) in the threaded hole (52) , said lock screw (72) being adapted to engage the flat surface (64) providing the fixed position of the cylindrical body (26) relative to the adjusting nut (54) .

15. The valve as claimed in claim 1, wherein said automatic releasing means (74) and said manual releasing means (90) are coaxially positioned partially within the bore (44) of the cylindrical body (26).

16. The valve as claimed in claim 3, wherein said automatic releasing means (74) includes a valve element (134) positioned in the bore (44) of the cylindrical body (26) and having a passage (138) therein, and means (82) for biasing the valve element (134) into contact with the seat (42)? and said manual releasing (90) means includes a seat (130) at the first end (28) of the cylindrical body (26), a passage (132) extending from the seat (130) to the bore (44) , a valve (98) having a sealing surface (100) and a stem (108) extending from the sealing surface (100) through the passage (132), the passage (138) in the valve element (134), and the bore (44) of the cylindrical body (26), a handle (112) connected to the stem (108) at an end opposite the sealing surface (100) , means (118) for biasing the sealing surface (100) into contact with the seat (130) , and means (120) for selectively retaining the manual releasing means (90) in the open position (104) .

17. The valve as claimed in claim 16, wherein said biasing means includes a compression spring (122) .

18. An engine having a plurality of compression chambers (12) the improvement comprising: a plurality of compression relief valves (10) each being connected to one of the plurality of compression chambers (12) , each of said valves having a cylindrical body (26) having a bore (44) , means (74) for automatically releasing a pressure from the compression chamber (12) and being partially positioned within the bore (44) of the cylindrical body (26), means (90) for manually releasing a pressure from the compression chamber (12) independently of the automatic releasing means (74) , said manual means (90) being partially positioned within the bore (44) of the cylindrical body (26) and having a means (20) for selectively retaining the manual means (90) in an open position/ each of the compression relief valves (10) being operative separate of each other so that the manual means (90) can be retained in the open position prior to starting and sequentially moved into the closed position one valve at a time to start the engine.

19. The valve as claimed in claim 18/ wherein said cylindrical body (26) has a peripheral surface (32) intermediate the first and second ends (28,30) thereof, an annular groove (38) in the peripheral surface (32), and a radial passage (46) leading from the bore (44) to the annular groove.

OMPI 20. The valve as claimed in claim 19, further including an adjusting nut (54) having a first end (56), a second end (58) and a bore (60) extending from the first to the second ends (56,58).

21. The valve as claimed in claim 20, wherein said automatic releasing means (78) includes a passage (50,128) extending from the seat (42) to the first end (28) of the cylindrical body (26) , a valve element (76,134) positioned in the bore (44) and adapted to contact the seat (42) , and means (82) for biasing the valve element (76,134) into contact with the seat (42) .

22. The valve as claimed in claim 20 wherein said manual releasing means (90) includes a hollow sealing valve element (76) positioned in the bore (44) near the first end (28) of the cylindrical body (26) said sealing valve element (76) having a sealing end (78), an opposite end (80), a seat (92) intermediate the sealing end (78) and the opposite end (80) , a passage (96) connecting the seat (92) with the opposite end (80) and a passage (94) connecting the seat (92) with the sealing end (78) ? a valve (98) having a sealing surface (100) adapted to contact the seat (92) and being movable between a closed position at which communication through the passage (96) is blocked and an open position at which communication is established through the passage (96)? and means (106) for manually actuating the valve (98) between the closed and open positions.

23. The valve as claimed in claim 18, wherein said automatic releasing means (74) and said manual releasing means (90) are coaxially positioned partially within the bore (44) of the cylindrical body (26) .