US1950561A - Reversing gear for internal combustion engines - Google Patents

Description

MCRH 193% J. c. MATTHEW REVERSING GEAR FOR INTERNAL COMBUSTION ENGINES Filed April 30, 1952 wa enfoz- Patented Mar. 13, 1934 PATENT OFFEUE BEVERSING GEAR. FOR INTERNAL COMBUS- TION ENGINES John Caesar Matthew, Mosigkau in Anhalt, Germany, assignor to Germany Application April 30,

Hugo Junkers, Dessau,

1932, Serial No. 608,496

In Germany May 4, 1931 7 Claims.

My invention relates to internal combustion engines and more especially to such engines which are reversed by means of compressed air.

In order to prevent damage from reversible internal combustion engines when started or reversed by compressed air, the following main principles should be observed:

(a) Compressed air for starting and fuel never should be supplied at the same time into the 10 working chamber of the engine, since otherwise inadmissible high pressures may occur.

(b) At all events the control of fuel supply must correspond to the direction of rotation in which the engine is running, since otherwise inadmissible vehement preignitions may occur.

(0) It should be possible to supply the compressed air for starting and reversing to the engine running in a given direction in a manner of control corresponding to the other direction of rotation in order to make possible a braking action on the engine, still running in the old direction, by means of the starting air.

Devices are known in which two different operating members (e. g. handlevers) are provided for, the one member for shifting the fuel supply control gear, the other for shifting the starting air control gear. In this case certain barring devices are necessary in order to prevent wrong manipulation, but these devices will complicate the apparatus and render its manipulation more difficult.

It is further known to shift both control gears (for starting supply and for fuel supply) by a single operating member. In this case the central position of the operating member corresponds to stoppage of the engine, the next two positions on either side (each side corresponding to one direction of rotation) corresponding to starting position and to normal running position or vice versa. However this arrangement also requires special provisions adapted to prevent undesirable shifting through starting positions and further barring devices against premature reversing of the fuel control gear before the engine has stopped.

According to my invention also a single operating member (e. g. shifting handle), is provided to which the control gears, for fuel and starting air, are connected in such a manner that its central position is the normal running position whilst the next two positions on either side are stop positions and the two outer positions are starting positions, one for forward and the other for reverse running. Further the fuel supply control gear is performed in a manner as to automatically work properly for either direction of rotation, said gear either being so designed as to be used unchanged in either direction of rotation or so as to adjust itself automatically according to the occasional direction of rotation.

This device is simple in design, easy to manipulate and fool-proof.

The simple design is founded on the fact, that only a single shifting member without barring devices and the like is required and that for the reversing of the fuel supply control members (e. g. fuel pump or fuel admission valves) no mechanical coupling of said members with the shifting member is necessary. It is not difficult to perform a fuel supply control gear working properly without ado in either direction of rotation (e. g. by driving cams for the fuel supply control gear shaped symmetrically to the dead centre position), especially for engines, the pump controlled fuel supply of which is finished before or at the inner dead centre, or for engines, the valve controlled fuel admission of which extends over a part of the crank circle lying symmetrically to the inner dead center.

In engines where the fuel admission is distributed otherwise over the crank circle, an automatic adjustment of the members (cams or the like) driving the fuel supply control members may be attained in a simple way by connecting these driving members to a driving shaft, positively coupled to the crank shaft of the engine, by means of a special coupling device allowing these members a certain angular movement with respect to the driving shaft. In multi-oylinder engines these cams or the like may be fixed to a cam shaft and the latter be coupled by one single coupling device with a driving shaft positively connected to the crank shaft. Moreover these cams may be shaped in such a way that the resulting turning moment which the fuel supply control members will exert upon this cam shaft comprises only resisting but not driving moments, and thus rattling of the mutual coupling device will be avoided.

The manipulation is simple, as a single operating member (lever or the like) makes it possible to go over from any working condition of the engine to any other working condition without leaving hold of it and without additional manipulation of any barring devices.

Finally the utmost security is obtained against trouble in starting and reversing as the object of this invention performs the conditions (a) to (c) mentioned in the beginning without any reservation.

- versing gear, illustrated by Figs. 2 to 4 the op- In the drawing aflixed to this specification and forming part thereof, embodiments of my invention are illustrated diagrammatically by way of example. In the drawing Fig. 1 is a diagram illustrating the shifting positions of the operating member.

Fig. 2 is a front view of the reversing gear in normal running position.

Fig. 3 is a front view in a stop position,

Fig. 4 is a plan view of that gear.

Figs. 5 and 6 are showing a cross-section, on the line V--V of Fig. 6 and a side elevation of a cam shaft and of its driving device for actuating the fuel supply gear of a multi-cylinder.

engine.

Fig. 7 is a front view of a specially shaped cam.

Referring to Fig. 1 I indicates the central position of the operating member whichin thatv case corresponds to the normal running position (fuel is admitted). This normal running position is common to both directions of rotation.

The next two positions II and II", on either side of the normal running position I, are stoppage positions (starting air and fuel are shut off).

The positions III and III, beyond the stoppage positions, are starting positions (starting air is admitted).

In the example of embodiment of the new reerating member is represented by a lever 1 fixed to a disc 2 which is pivotally mounted on a shaft 4 carried by the fixed support 3. The fuel supply to the engine is controlled by a pump 5 9 which is driven by a cam 6 placed on the shaft 7.

This cam is shaped symmetrically and connected to the shaft '7 by means of a coupling device consisting on the one hand of a bow shaped groove 8 in the cam with the end faces 9, 10 and on the other hand of a stud 11 on the shaft '7, projecting into said groove, so as to allow the cam a certain angular movement with respect to the shaft. If the shaft '7 rotates in the direction of the arrow a the left side of the projection 11 will lean against the left endface 9 of the groove 8 and then the cam 6 is taken around with the shaft 7. If the shaft '7 is reversed the .cam 6 at first is held back by the resistance of the pump until the other side of the stud 11 reaches the end face 10 of the groove 8, then the cam.

is taken around in the reversed direction. Thus,

at'reversing the engine, the cam performsautomatically a certain angular movement with re-, spect to the shaft 7 and consequently the control gear of the fuel pump will work properly for both directions of rotation.

The disc 2 has two peripheral cams 12, 13 and between them a groove 14 into which, at the normal running position I, the nose end 15 of a bell-crank lever 16 projects, whilst its other end 17 lies below a projection 18 of the pump. tappet stem, however without preventing the action of the pump, (Fig. 2). The earns 12, 13 are so shaped that, the lever 1 being shifted from position I to any other position, the nose 15will.

be moved to the right, to such an extent that the end 1'7 of the lever will lift the pump tappet stem 19 as much as toget free from the cam 6.

The gear for the starting air supply control comprises a sliding sleeve 26 mounted on.v the shaft 7 unturnable with respect to it but shiftable in its axial direction. This sleeve 20 bears the cams 21 and 21", one of them operating the starting valve 25 at starting in the forward direction, the other at starting in the reverse direction. The cams have inclined surfaces at their sides facing each other which will lift the starting valve stem when the sleeve 20 is shifted and supposed that the valve stem is just in the shifting way of the respective cam. The starting air enters the starting valve case 24 at 23 and flows through the pipe 26 to the working chamber as soon as the starting valve 25, which is permanent lyflloaded by a spring 27 in the sense of closing, is opened by-oneof the two cams 21' or 21. The shifting of the sleeve 20 is effected by means of a front cam 30 which is attached to the disc 2 andhas three steps 31-, 32, 33 interconnected with one another by inclined passages, and by means of a double armed lever revolvable about the fixed pivot 35 one end 34 of said lever being permanently pressed against the cam 30 by a spring 38, the other end 36 catching in a groove 37 of the sleeve 20. The middle step 32 is as long as to allow the lever end 34 to slide up to the higher step 31 or down to the lower step 33, only if the handle 1 is shifted beyond one of the two stoppage positions II II".

The mechanism works as follows:

When the engine is at rest the. operating member (lever 1) will be in one of the two stoppage positions II or 11", for example in II (Fig. 3). The fuel pump 5 is shut off, the sleeve 20 is in its middle position, the starting valve 25 is closed. For starting the. lever 1 is shifted into the starting position for. the wanted direction of rotation, that is into the adjacent startingj position III or, passing the. normal running position I and the other stoppage position II", into the other starting position III. Thereby either step31 or. 33 of the front cam 30 comes to lieagainst the lever end'34, and consequently the lever is-turned roundits pivot 35 and the other end 36 of it shifts the sleeve 20 so that one of thestartingcams 21' and 21" comes in line with the stem-of the starting valve 25 which consequently is opened and thus admits starting air to the working chamber. As soon as the engine hasstarted the handle 1 is shifted backwards through, the, adjacent. stoppage positioninto the normal running position I (Fig. 2). Thereby the lever end 34 returns to the step 32 of the cam30; thus the starting air is shut off again, the nose 15 of the lever 16 enters the groove 14 between the cams 12 and 13, thereby the fuel pump is set to work, the cam 6 of. which, in consequence of the arrangement of the coupling device, automatically is put into that position, which correspondstothe chosen direction ofrotation.

For stopping, the handle 1 is shifted from the normal running position I at will into one of the two adjacent stoppage positions II or II.".

In order to reverse the running engine the handle 1 at once is shifted from the normal running position I into, ,thefstarting position of the. reversed direction of rotation (for instance III), thereby passing the stopping position IIf' between them When the starting position III) is reached the breaking action of position) theoperating member only can pass the harmless stoppage positions or, the normal running position in which for every direction of rotation the fuel supply control members will automatically adjust itself properly, but avoids passing through undesirable starting positions or through normal running positions with admission of fuel not corresponding to the actual direction of rotation. No manipulation of the operating member, however it may be, ill cause risk for the engine. On this account barring devices against wrong manipulation are not necessary.

If the cams for driving the fuel pump members are connected individually to the control shaft by means of the above mentioned couplings the disadvantage arises, that in pushing these members a resisting torque acts upon the cams whilst in the backwards movement of these members in consequence of their pressure upon the cams (for instance effected by th spring which pulls out the piston) a driving torque acts upon the cams and this torque arising alternatively in opposite directions will cause a hammering action between the cam-groove faces 9, 10 and the studs 11 in consequence of which undue rattling and excessive wear of the coupling parts will occur. In multi-cylinder engines in which the fuel supply takes place on different parts of the crank circle, an improvement of this disadvantage will be attained by fixing the cams, driving the respective fuel pumps, to a common shaft, the latter being connected to the crank shaft by means of only one above described coupling device. Consequently resisting and driving torques will act more or less synchronically on the different but rigidly interconnected cams and therefore the driving torques will be neutralized at least to a certain amount.

Such a fuel supply control gear is illustrated in Figs. 5 and 6. Several cams 40, displaced against each other in angular direction, are fixed to the cormnon shaft 41 which is connected by means of the aforesaid coupling to the driving shaft 42. The coupling consists of a disc 43 with a sectorlike groove, fixed to the driving shaft 42, and of a crank pin 46 fixed to the disc 47 of the cam shaft 41. This pin 46 projecting into the groove of the disc 43 has a certain angular play between the end faces 44, 45 of the groove. Thus the shaft 41 is enabled to perform the angular movement with respect to the shaft 42 necessary for reversing.

The disturbances, caused by the driving torques may be completely overcome in devices where the fuel supply is controlled by pumps. This possibility is based on the fact, that it is admissible to place the suction stroke of the pump piston at a convenient part of the crank circle, not needed by the pressure stroke. Regarding this the top of every cam is elongated between the rising surface m and the descending surface n, as shown in Fig. '7, and this elongated top 2" extends over an angle 6 of such an amount, that the driving forces exerted upon the descending surface of one cam will be effective quite synchronically with the greater resisting forces acting on the rising surface of another cam; thus the first named forces will be compensated in every position of the cam shaft. In consequence thereof a constant touch between the driving and driven members of the coupling is guaranteed.

Various changes may be made in the details disclosed in the foregoing specification without departing from the invention or sacrificing the advantages thereof.

In the claims affixed to this specification no selection of any particular modification of the invention is intended to the exclusion of other modifications thereof and the right to subsequently make claim to any modification not covered by these claims is expressly reserved.

I claim:

1. In a reversing gear for internal combustion engines, in combination, means for supplying fuel to the engine, mechanism for operating said fuelsupplying means, means for automatically moving said mechanism into the position corresponding to the direction of rotation imparted to the engine, a valve for admitting starting air, valve gear for operating said valve, means for placing said valve gear in two active positions and one inactive position with respect to said valve, means for throwing out said fuel-supplying means when said valve gear is in its active position, and a controlling lever for operating said valve gear and said throwing-out means.

2. In a reversing gear for internal combustion engines in combination, means for supplying fuel to the engine, a cam for operating said fuel-supplying means, means for automatically moving said cam into the position corresponding to the direction of rotation imparted to the engine, a valve for admitting starting air, valve gear for operating said valve, means for placing said valve gear in two active positions and one inactive position with respect to said valve,.means for throwing out said fuelsupplying means when said.

valve gear is in its active position, and a con trolling lever for operating said valve gear and said throwing-out means.

3. In a reversing gear for internal combustion engines in combination, means for supplying fuel to the engine, a shaft operatively connected to the engine so as to rotate in opposite directions as the engine is reversed, a cam on said shaft adapted to operate said fuel-supplying means, clutching means intermediate said cam and said shaft which means permit rotation of the shaft through a given angle with respect to the cam, a valve for admitting starting air, valve gear for operating said valve, means for placing said valve gear in two active positions and one inactive position with respect to said valve, means for throwing out said fuel-supplying means when said valve gear is in its active position, and a controlling lever for operating said valve gear and said throwing-out means.

4. In a reversing gear for multi-cylinder internal combustion engines in combination, means for supplying fuel to the engine, a shaft operatively connected to the engine so as to rotate in opposite directions as the engine is reversed, a cam shaft having a cam per combustion chamber' in the cylinders of said engine for operating said fuel-supplying means, clutching means intermediate said shafts which clutching means 1 permit rotation of the first-mentioned shaft through a given angle with respect to said cam shaft, a valve for admitting starting air, valve gear for operating said valve, means for placing said valve gear in two active positions and one inactive position with respect to said valve, means for throwing out said fuel-supplying means when said valve gear is in its active position, and a controlling lever for operating said valve gear and said throwing-out means.

5. In a reversing gear for multi-cylinder internal combustion engines in combination, means for supplying fuel to the engine, a shaft operatively connected to the engine so as to rotate in opposite directions as the engine is reversed, a

cam shaft having a camper cylinderof theie'ngine for operating said fuel-supplying eansthe' cams on said shaft being so designe'd that the" action which the forces resulting mm the operation of said fuel' supplying means exert on one of said cams, is balanced by the action of said forces on another cam, clutching means inand's'aid throwing-out means. g

6. In a reversing gear for internal combustion engines in combination, means for supplyingfu el to the'engin'e, mechanism for operating said-fuel supplying means, means for automatically moving said mechanism'into the position correspond ing to'the direction of rotation imparted to the engine, a valve for admitting starting air, valve gear for operating said valve comprising a pair of cams for alternately operating'said valve, a

controlling lever, means operatively connected to said lever for selectively presenting one of said" cams at a time'to, and for placing both cams in inactive position with respect to, said valve, andi siel g,Qi 'a v y q'n' ed' t said lever forthrpwihg-out s'aid fuel-supplying means in the positionof; saidleve'r which corresponds to the active position of-said cams.

7 lust-reversing gear for'int'ernal' combustion enginesinfcombinaticnfmeans for supplying fuel to thfefleng ine;mechanismfor operating said fuels upplying-means, means for automatically movirig" said'rnechanism into the position correspondm t9 the ,di ec qn of rretai im t to the engine; valvelfqr admitting starting air, valve gear for operatin gsaid valve, comprising a'pair of Canasfor aiterriately' operating said valve, a controlling lever, a cam plate operatively connected to said lever, a set of; camr ning members on said c'arii plate, meansj operatively connected to said (jamming membersfo selectively presenting one of saidcams ata timeto, and for placing both cams i ri inactive" position vvith respect to, said valve, another set 0 f cainming members' on said' valve plate', and mean or throwing outsaid fuelsupply-ing meansop e'ratively connected to said last m'entioned; camming" members; Which lastmeiition'ed camming members are so positioned with respect to" the first-mentioned camming members that said fuel supplying means are thrown out when oneof said camsis presented to-s'a'id-valv'e; and throvvn inwhen said'ca'ms are in-their inactive position.

JOHN CAESAR MATTHEW.

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