US1734673A

US1734673A - Wilhelm hefti

Info

Publication number: US1734673A
Authority: US
Publication date: 1929-11-05
Anticipated expiration: 1946-11-05

Description

Nov. 5, 1929. w. HEI-'Tl AIR STARTING GEAR Filed oet. 4, 1925 Patented Nov. 5, 1929 llNlTED STAT'ES .PATENT FFECE WILHELM HEFTI, @E TTULFLNGEN, SWTZERLAND, ASSTGNOR TO BUSCH-SULZER BROS. DIESEL-ENGINE C0., OF ST. LG'UIS, MISSOR, A CGRPORATION OF MSSOURI AIR STARTING GEAR Application filed Uetober 4, 1923, Serial No. 666,656, and in Germany April 5, 1918.

My invention is an improvement in the starting gear for internal combustion engines of the lrind which are set in motion 'by the timed admission of compressed air, and the invention consists in the principle of organization and mode of operation herein below described whereby such gear can be compactly made and applied to the engine and whereby certain desirable effects can be produced looking toward the most efficient use of the pressure fluid and other desirable results. The invention is primarily intended for engines of the Diesel or fuel injection type, may be used for re-starting in reversing the engine as well as for starting from stand still, and is applicable to both two and four cycle engines. In addition to providing for the timed admission of compressed .starting air, the invention comprehends a pressure relief valve complementing the engine eX- haust ports and to relieve certain compres sions which otherwise resist the starting action. It also comprehends a shut-olf or supplementary valve to prevent access of the cylinder products and hot gases to the air and relief valves, this shut-olf valve being operated so as to be opened with the initiation of the starting action and held open d uring the subsequent steps of the starting process.

T he accompanying` drawings illustrate the invention applied to a two-cycle ,fuelinjection engine. Fig. 1 is a sectional elevation of a portion of a single cylinder of such an engine and the valves of my starting gear applied thereto. Fig. 2 is an elevation of the lever mechanism controlling` the operation of these valves, portions of which are shown in Fig. l. Fig. 3 is diagram illustrating the cycle of operation of the starting valves. Figs. l and 5 are plan views of details.

In the form of the invention illustrated7 both the air admission valve and the pressure relief valve are arranged in a valve box l. which may be mounted directly on the cylinder 2 as indicated or may be otherwise put in communication with the cylinder combustion space through the pipe or passage 3. An adjunct of this pasasge is the shut-off or supplementary valve 4f which prevents access of the hot gasses and cylinder' products to the air admission and relief valves and hence maintains these valves in a clean and operable condition. ln its preferred form, this shutoff valve is a poppet valve located at the cylin der end of the passage 3 and is so faced as to be held to its seat by the pressure within the cylinder; aspring la closes or assists in closing it. lts stem is accesible for independent action by mechanism later described (including a lever 30) 7 so that rthe shut-off valve is opened and held open only when the engine is to be started by the compressed starting fluid,-in this case airy-as before stated. A fuel injection valve is shown at 20 for the cylinder illustrated and the exhaust port 2l is shown in vlfig. 3 adapted to be uncovered by the piston as usual in two cycle engines. The pressure fluid enters the valve boX inlet chamber 5 through a lateral connection 6, from an air reservoir not shown, and from thence passes to the passage and to the engine under the control of the valve member 7 which I term the starting valve and which incorporates both the air admission valve and the compression relief valve in the present instance. The air admission valve part of the member 7 comprises two portionsa a cylindrical sliding valve portion 7a fitting the passage in the wall separatin the inlet chamber 5 from the pasg-e 3:. and immediately above it a larger poppet-valve portion 7b. which seats against the chamber side of the same wall and is adapted to be urged to its seat by the pressure of the starting air. The valve member 7 also has two cylindrical guiding extensions 7C and 7d, the former being of a diameter nearly equal to or commensurate with the diameter of the poppet valve 7b and having a sliding fit in a bushing in the upper portion of the box l (Fig. l) so that the starting air pressure in the inlet chamber 5 is denied free access to the space .between the end of this extension and the valve box cap 9. The purpose of this ap pears hereafter. The lower guide 7d extends through the lower end of the valve boX for actuation by the valve operator 31. A spring 8 interposed between the valve boX cap 9 and the valve member 7 also urges the valve to its seat; the extension 7C is preferably liollowed ISC out and the spring 8 is housed within it. The segregation of the space between the cap 9 and the valve extension c-comprehended by the chamber 15,-ie for valve balancing purposes. Normally this chamber contains air under reservoir pressure admitted through the small leak port '1G so that reservoir pressure may act over the whole projected area of the propet valve 7b to seal the passage between the .inlet chamber and the cylinder passage 8. A venting valve 14 is adapted to break this pressure by venting thechamber 15 to the atmosphere just prior to the unseating` of the poppet or sealing portion .Ybo'f the air admission valve: this air exhausts by Way of the

passage

18 and 19, 'Inasmuch as the leal; port 16 relatively small, Athis venting of chamber 15 substantially relieves the poppet valve 7b of the pressure of the starting air over an' area corresponding to the diameter of the extension 7C and accordingly .the starting` air valve is readily lifted For operating the two valves 14 and .7b in the order stated., the ,lower end of the vent valve 14 carries a ianged cap 23 against which the lifting` lever 31 bears and .'hich is slightly separated from the lower end of the valve member 7 when .both valves Aare closed. llVhen the lever 3l is operated, it

first lifts the vent valve 1.4 from its seat and then brings the cap into contact with the valve member Z to lift the latter. The port 16 is closed by its bushing, or the passages 18 are closed by the wall between the chamber 3 and the exhaust passage 19, or both, shortly after the valve member 7 begins its lift, so that there .is no substantial escape of starting air by way of the leak port 16 and the vent valve. The vent valve 14 is normally held to .its seat by the air pressure of the chamber 15 as well as by the spring 24 which bears against the same spider 25 as the spring 8.

The relief valve in the present instance is constituted by a part of the guiding extension 7d of the valve member 7, namelythe portion of this extension in the ref-ion of the vent passages 18; this portion ofthe valve member forms a slide valve Aitting the passage in the wall separating the cylinder ypassage 3 from the exhaust passage 19.. As shown. in the drawings, this relief valve isopen when the starting valve member 7 is Ain 4its lowermost position and the air admission valve Ya-ft is closed. The slide valve portion 7a however, provides for .some overlapping of therelief valve and the air admission valve. Th at is to say, the iirst upward movement of the valve member? raisesthe poppet .7b from its seat and breaks the seal between the starting air reservoir and the cylinder, but the parts are so `proportioned that the slide valve 7a does not entirely enter the inlet chamber 5, to open communication .from 5 to 3,`until after the relief valve V'7d haslpassed into the wall be- *ri-.veen` Band 19 and closed the outlet fronrthe passage 3 to the atmosphere. In the reverse movement of the valve member 7, the slide valve 7a closes before the relief valve 7b opens the cylinder to the atmosphere. In short, intermediate the illustrated position of the valves and their uppermost position, there is a lap position in which both the air admission valve and the relief valve are closed.

The cycle of operationsV of the described valves f s used with two-stroke-cycleengines will be understood from Fig. 3, assuming the supplementary shut-oftl valve 4 to be held open: When the engine piston has passed dead center at the beginning of its'outward or power stroke, the valve member 7 is in its uppermost position and thevalves 7a and 7b are both open .and the compression relief valve 7d closed. Accordingly, airppasses from the reservoir through the inlet chamber .5 and ,passage' to the cylinder land drives the piston outwardly. The air and relief valves may be continued in this .position until the piston opens the engine exhaustportQl, but preferably before thepiston reachesthis position, the valve member 7 lis allowed to fall far enough for Athe slide valve .7a `to stop the flow of starting air to theenginefbut not so far as to open the compression'relief valve 7d, so that theadmittell air charge may act ei;-

pansively on `the engine piston Ifor the .rei mainder of the piston stroke. This operation is diagrammatically represented lin Fig, 3 where arc m represents the airadmission period and Iarc a the period of lapped condition in which .no air is admitted or allowed to escape. The rperiod .a continues until the engine :piston opens .the engine exhaust port 21, or shortly thereafter. At the end of period n the relief valve 7d is opened Aand preferably the poppetb is closedV at the same time and this Vposition of the valves is maintained throughout/the period representerlby the arc 0, during which the momentum of the engine or `the action of the starting air onanother or other cylindersconti-nues the engine in motion, During the first part of this period o the. starting air is exhausting through therengine exhaustport .21, that .is while the latter is uncovered by the piston; after lthe exhaust port is closed .the compression relief valve 7d and port 19 continues the exhaust throughout the remainder ofa period 0thereby avoidingjthe recompression of thepart of the air by the Vpiston dn its return stroke and the opposition to the starting action caused by such compression. At or near t-he dead eenterposition at the end of this (normally acompression) stroke, the relief valve 7d is again closed and again the startingair valves are opened, repeating the starting cycle as `above explained.. While the arc 0 may continue up to the very beginning of the period m, it is preferable that the air and 1,. ff valves be .lapped again sufficiently Vin advance ofthe beginning of m to permit llO the building up of such a compression within the cylinder as may be desired for the conservation of the starting air. The arc p ilhistrates the part of the cycle in which the compression relief valve 7d may be held closed (the valves lapped) in advance of the period m. By repetitions of this cycle of air operation, no fuel being furnished to the engine during this time, the engine is brought up to such a speed that the normal operation on fuel may be begun as is well understood. The air operation is then entirely discontinued, the shut-off valve 4 closed, and fuel is furnished to the engine and the latter continues in operation as an internal combustion engine.

rEhe preferred mechanism whereby the various valves of the invention are actuated in accordance with the cycle of operations described, is illustrated somewhat diagram- 'matically in Fig. 2. rI`he parts as shown in full lines are in position for starting ahead, the valves being in the positions indicated in Fig. l. A rock shaft 35, carrying an eccentric fulcrum 40 for the valve lever 41, is employed to put the starting mechanism into and out of action; in the case of a multicylinder engine this fulcrum shaft may be common to a number of cylinders. The shaft is rocked in its bearings (not shown) by a hand lever 36 for example, which in the position illustrated in full lines, causes the engine to be actuated by air as before described; in the dotted line position 36a of this handle, the shaft 35 is so placed that the starting air gearing is entirely out of operation as will later appear. In accordance with my invention a correlation of the shut-off valve 4 with the control members of the starting gear opens the supplemental shut-off valve 4 on the initiation of air starting and holds it open during the subsequent starting process. For this purpose, as herein shown, a cam member 37 is keyed to the control shaft 35 and operates the valve lever to open the valve 4 whenever the handle 36 and its rock shaft 35 are shifted to the air starting position, said valve being thus held open as long as the starting mechanism is in operative condition. A spring 4EL serves to close the valve 4 when the handle is shifted to its position 36a. It will be apparent that any other suitable form of connection between the handle 36 and the valve 4 may be arranged to produce the effect above described. When the shaft is shifted to the air starting position the valve lever 41 is brought to bear against the rock lever 3l which directly actuates the vent valve 14 and valve member 7 as before described, and also into operative relation to the engine driven cam or cams by which it is actuated. rEhe gearing illustrated being for a reversible engine, the cam end of the rock lever 4l has pivoted to it a commonly used form of cam roller bracket 42 carrying two cam rollers of which the roller 43 is in the plane of the astern cam 44 on the cam shaft 45 while the roller 46 is in the plane of the ahead cam 47. The link 48 may be assumed to be fixed to a suitable operating handle which, in the four positions indicated by broken lines in the drawing acts to hold the

rollers

43 and 46 in such positions as to secure the action indicated by the corresponding legends, and as will be understood by those skilled in the art. A spring 53 may be used to hold the left hand end of the lever 4l (Fig. 2) in constant engagement with the rock lever 3l and also to hold the lever 4l out of operative engagement with the cams on the cam shaft when the handle 36 is shifted to its position at 36a in which the eccentric elevates the roclr lever 41" from the cam shaft, and the starting mechanism is out of action. The cam shaft 45, in the present instance, is intended to be engine driven at the same speed as the engine crank shaft, and the

cams

44 and 47 are laid out to secure the cycle of operation illustrated in Fig. 3, although as pointed out with respect to that figure and as will be evident, this cycle of operation is subject to variation according to the particulars of the engine to which the invention is applied and the effectdesired. In these and other ways, the particular form of my invention illustrated in these drawings is subject to change without departing from its principles, and it will also be understood that while I have illustrated and described my invention with respect to only a single cylinder, the invention is adapted for multicylinder engines; each cylinder of such engine may be provided with a set of valves like those shown in Fig. l and a system of operating levers and cams such as illustrated in Fig. 2.

I claim:

1. In an internal combustion engine having a cylinder providing a space within which the piston operates, the combination of air starting and compression relief valves, a shutoff valve between said valves and the piston space, said shut-off valve being normally closed to prevent access of the cylinder contents to said air and relief valves, means for operating the air and compression relief valves. and means for holding the shut-off valve open when the engine is to be operated by compressed air and for bringing the first mentioned means into operation to actuate the air and compression relief valves.

2. Starting gear for internal combustion engines comprising a single engine-driven member, air starting and compression-relief valves so mutually related to each other and to said engine driven member as to he opened and closed by movement imparted by the engine driven member, one being opened when the other closes and vice versa, a supplementary valve between said valves and the interior of the engine cylinder, mechanism to bring said engine-driven member iut) intofand out of 'operating relation with said startingand compression-relief valves, and means co-operating with said mechanism to open said supplementary valve when said engine-driven member is brought into operating relation, and to close said supplementary valve when said engine-driven member is brought out of operating relation, so that the supplementary valve is held open during the whole period that the engine-driven member is in operating relation to said starting and compression relief valves.

3. The combination with an internal combustion engine, of starting` air and compression relief valves, a shut-olf valve, engine driven means for operating` said starting air and compression relief valves in timed sequence, mechanism for connecting said starting air and compression relief valves to said engine driven means for operation thereby, a control member for putting said connecting mechanism into and out of action at will, and another member operated by said control member for opening said shut-olf valve when'the connecting mechanism is brought into action, holding the shut-off valve open, and closing the shut-off valve when ythe connecting` mechanism istalren out of action.

4. The combination with an internal combustion engine, of air starting gearing therefor comprising a starting `air valve, a compression relief valve, a poppet shut-off valve for preventing access of the cylinder contents to the starting` air .and pressure relief valves, said poppet shut-off valve being faced. to be held to its seat by the pressure within the cylinder, an engine-driven clam shaft operating said starting air and compression relief valves, a connector between Ysaid cam shaft and valvesi control means operable at will for bringing said connector into action between said cam shaft and the valves operated thereby, and a member connected to and operated bysaid control means for opening the shut-off valve when said `control means is operated to make the said Iconnection between the cam shaft and valves and to close said shut-oftl valve when said connection is broken, so that the shut-off valve is held open when said connector is in position to cause the operation of the air and compression relief valves by said cam shaft.

5. The combination with an internal combustion engine including `an engine-driven cam-carrying shaft, of anair starting gear comprising an air starting' valve, a compression relief valve, connector means between said valves and said cam-carrying shaft through which the said valves are operated by said shaft, a control shaft for putting said connector means into and out of operation, ashut-oif valve for preventing access of cylinder contents to the air starting and relief valves, and a cam on said control shaft and a connector from the same to the shut-od valve through which the shut-olf valve is held 6. The combination with an internal combustionengina of a poppet type starting air valve held to its seat 4by the starting air pressure, a compression relief valve, -a vent valve which when open breaks the pressure of the starting lair on the starting air valve, an engine driven cam, asingle operating connector between said cam and said valves through which all said three vvalves are operated, said vent valve being operated to relieve the pressure on starting air valve in advance .of the openingof the latter valve, control means for putting said connectorinto and out of operation at will, `-and a shut-off valve.

7 '7. he combination .with an internal combustion engine provided with a single passage to a cylinder for the admission and relief of starting air, of a poppet shut-olf valve at the inner end `of said passage disposed to be urged to its seat by 4pressure within thecylinder, a valve box adapted to be fixed to the cylinder at the outer endof said passage, and

havin a pressure relief port'and a connection toa source of compressed vair, an air valve in said box arranged to admit compressed air Y to said passage, a relief valve in said box controlling the escape of pressure from the 'ffiassage to the relief port, said valvesbeing juxtaposed so that movement of the relief `valve beyond its closing position opens the air valve, a two-stage cam imparting motion to therelief valve to operate both the relief valve and the air valve, the stem of the shutoli: valve passingthrough an individual opening in the cylinder wall for independent actuation, and means for connecting the air and relief valves to said two-stage cam and disconnecting the same .therefrom at will, said means also acting on said stem of the shutolf valve to hold the same .open when said cam is actuating said air and relief valves.

S. ln an internal combustion engine, having a cylinder providing a space within which a piston operates, the .combination of airstarting and compression'reliefvalves, a separate shut-off valve between said valves and the piston space, said shut-olf valve being closed to prevent accessvof thecylinder contents to said air and relief valves while v,the

ing a cylinder providingvaspace within which a piston operates, the combination of airstarting and compression relief valves, a, Separzttely operable @hut-oft1 valve between the same and the cylinder space to prevent ac- Cess of cylinder contents to the air and relief valves during fuel operation, engine-clriven cam means for operating said air and relief valves7 t connector between said cam means and the air and relief valves, a control shaft, said connector being so mounted on the control shaft that turning the Control shaft places the connector in valve operating position or displaoes it therefrom, and means for holding the shut-olf Valve open when the engine is operated by air, the last mentioned means being` operated by said Control shaft.

ln testimony whereof, I have signed this specication.

VILHELM HEFTI.