US2080079A - Supercharger - Google Patents

Description

May 11, 1937.

SUPERCHARGER Filed Nov. 4, 1953 f9 4 57 1 3 6 6 55 i s 54 f2 5 Z 36 58 o A INVENTOR. H 24 45 48 GLENN 0. JOHNSUN .12 1 2 46 ATTORNEY.

G. D. JOHNSON 2,080,079 1 Cal til

Patented May 11, 1937' UNITED STATES PATENT OFFICE SUPERCHARGEB Calif.

Application November 4, 1933, Serial No. 696,685

6 Claims.

This invention relates to superchargers for internal combustion engines, and has forits object to adjust the speed of a supercharger while an engine is in operation and thus vary the pressure at whlch'the combustible charge is supplied to the engine.

The invention is particularly applicable to aviation engines where supercharging is resorted to for maintaining engine efficiency in the rarefied air encountered at high altitudes, and the present invention provides for adjusting the speedof the supercharger impeller while the aircraft is in flight and in accordance with change in altitude, so that at low altitudes the impeller may be driven at a relatively slow speed whereby the combustible charge is compressed to no appreciable degree before it is supplied to the engine and the impeller functions merely as a mixer for the combustible charge, while at high altitudes the speed of the impeller is increased so as to force the combustible charge into the engine under pressure and thus compensate for the lesser density of the air which is drawn into the carburetor at these higher elevations.

More particularly it is an object of the invention to couple the impeller of a supercharger to an internal combustion engine by a selectivespeed driving connection having a manual control, whereby the impeller may be rotated at idling speed at low altitudes, with the power of the engine maintained constant as altitude increases by gradually opening the throttle valve of the engine, and at the will of the operator and when higher altitudes are reached the impeller may be rotated at high speed forcompressing the combustible charge and forcing'it into the engine cylinders at a pressure in excess of the surrounding atmospheric pressure, in order to maintain constant power up to a still higher altitude.

It is a further object of the invention to'provide a yieldable coupling in the driving connection for the impeller, whereby some slippage may occur so as to avoid breakage when the engine' speed is changed suddenly, and to preferably employ a friction clutch as the yieldablecoupling, with the friction clutch providing means for selecting a desired speed ratio for the driving connection.

It is a still further object of the invention to adjust the tension of the friction clutch so as to permit only such slippage as will avoid breakage, and to make the adjustment from a point which is readily accessible from the exterior of the housing for the driving connection.

It is a still further object of the invention to adapt the selective-speed supercharger for incorporation'in a usual engine assembly wherein the, supercharger comprises animpeller rotatable in a casing mounted on the main housing of the engine broken away to show the driving connection.

Fig. 2 is an enlarged axial-section through the countershaft of the driving connection.

:The supercharger is illustrated in connection with an aviation internal combustion engine comprising an annular housing I having radial cylinders, one of which is shown at 2, with a crank shaft 3 projecting rearwardly through a partition 4 which forms the rear wall of a crank case 5, and a propeller shaft 6 projecting forwardly from a front section I of the annular housing.

, In accordance with usual practice 'a supercharger of the centrifugal compressor type may be mounted on the annular housing I, and is shown as comprising a diaphragm 8 closing the rear of the annular housing, with a casing 9 overlying the diaphragm and cooperating therewith to define an impeller chamber I l surrounded by a diffuser chamber l2 which is in turn surrounded by a distribution chamber I3. An inlet It to the impeller chamber is connected to a carburetor (not shown) by a supply pipe I5, and intake pipes i5 lead from the distribution chamber I3 to the respective intake ports of the engine cylinders. An impeller I1 is adapted for rotation in chamber H, and may be splined on a shaft IB which is journaled in an anti-friction bearing I9 mounted in a bearing collar 20 on the diaphragm 8, and a driving connection between crank shaft 3 and impeller shaft I8 is mounted .in the restricted space forming a drive chamber 2| between the diaphragm 8 and the partition 4. In the present invention this driving connection is a selective-speed driving connection which preferably includes a yieldable coupling, with the selective-speed driving connection adapted for manual control and the yieldable coupling having tensioning means adjustable from an accessible point at the exterior of housing 1.

tion for reception in the restricted space which is formed by drive chamber 2|, the shaft |8 preferably has its end which projects into the drive chamber journaled in anti-friction bearings 22,

which are mounted in a bearing recess 23. formed in the end of the crank shaft 3; and a countershaft 24 is joumaled in chamber 2| alongside the shaft l8, with the countershaft journaled in axially spaced anti-friction-bearings 25-26. The bearing 25 may be mounted in a bearing collar 21 which is suspended from housing and the bearing 26 is preferably mounted in a bearing collar 28 projecting from the diaphragm 8.

The selective-speed driving connection comprises gear trains of difierent speed ratio connecting the crank shaft 3, countershaft 24 and impeller shaft IS, with means for selectively engaging the respective gear trains. For this purpose a drive gear 36 is splined on the end of crank shaft 3 which projects into chamber 2|, with the periphery of the gear axially ofiset so that it is closely adjacent the partition 5, and this gear may be held in place by a threaded collar 3|, and meshes with a driven gear 32 which is splined on countershaft 24 and which has a hub 33 journaled in the bearing 25 and engaged by a threaded locking collar 34.

Between the bearings 25-26 a pair of selective drive gears 35-36 of different diameter are jour-.

' speed drive for impeller l1, and when gear 36 is rotated by the countershaft the gears 36-38 form a'high speed drive.

The gears 35-36 are selectively driven by the countershaft 24, and the driving connection is preferably adapted to yield to permit some slight slippage and thus avoid stripping the gears when the driving connection is suddenly speeded up, as for example when the engine throttle is suddenly opened. For this purpose the proximate faces of gears 3546 form frictional clutch faces ii-42, and a cooperating frictional clutch flange 53 projects radially from countershaft 24 between the proximate clutch faces 41-42. The flange 43 has frictional clutch elements 44 at its respective faces, and the countershaft 24 is adapted for axial movement. to selectively frictionally engage the clutch elements of flange 43 with the clutch face of one or the other of gears 35-36. A manual control is provided for axially shifting the countershaft to selectively frictionally engage the gears 35-36, and means are provided for ten-.

sioning the countershaft when shifted to either of its operative positions, with the tensioning means readily adjustable so as to normally maintain frictional engagement at the clutch, but adapted for some slight slippage in the event of a sudden strain on the driving connection.

As an instance of this arrangement the countershaft 24 projects outwardly beyond casing 9, being 'slidable in a guide bearing "45 which bridges the diffuser chamber l2, and axial shifting of the countershaft is preferably limited by a collar 46 integral with the countershaft and slidable in a the opposite end of the lever.

I space in back of bearing 26 so that the collar abuts the bearing 26 or the base of bearing recess 28 as shown at Figs. 2 and 1 respectively. A lever 41 is connected to the outwardly projecting end of the shaft 24, with the shaft end preferably journaled in a bearing 48 which is mounted in a housing 49 to which the lever is pivoted as shown at 50, and the lever may be fulcrumed at an intermediate point on a bracket projecting from casing 9, the fulcrum being indicated at 5|, with a manually controlled operating rod 52 pivoted to A spring 53 is adapted for movement beyond dead center when lever 61 is manually swung so as to project or retract the shaft 24 for engaging one or the other of the clutch connections at flange 43, and the spring thus maintains the lever in its shifted position and tensions the clutch engagement, but is adapted to yield to permit some slippage at the clutch in the event of sudden strain.

The spring may be adjusted to regulate the tension of the frictional clutch engagement, and for this purpose is shown as a coil spring guided on telescopic pins 55-55 which project from end plates 56-51 between which the spring is mounted. The end plate 56 is swiveled to the end of lever 41 as shown at 58, and the end plate 51 is swiveled at 59 to a bolt 60 which is adapted for threaded adjustment through a plate 6| supported by the casing 9. The tension of spring 53 may thus be regulated by threaded adjustment of bolt 66, with the bolt preferably held in adjusted position by a lock nut 62.

Tendency to. slip will be greater at the high speed clutch connection 43-42 than at the low speed clutch connection 43-4l, and therefore the spring 53, after being adjusted by its bolt 66, is preferably adapted to maintain a greater tension at the clutch connection 43-42 than at the 'clutch connection 43-4l; but on the other hand stripping of the gears is more liable to occur at high speed, and therefore the greater tension at the high speed clutch connection is preferably such as to only partly overcome the greater tendency of this clutch connection'to slip, so that it will yield responsive to an increase in resistance which is slightly less than that which will cause slippage at the low speed clutch connection. For

this purpose the plate 6| is preferably adjustable on a bracket 63 which projects from casing 9, the adjusting means being shown as a bolt and slot connection 64; and the plate 6| is adjusted for laterally offsetting the swivel connection 59 with relation to fulcrum 5|, so that when lever 41 is shifted for engaging the high speed clutch connection 43-42 as shown at Fig. 1, the spring 53 is swung a greater distance beyond dead center than when the lever is shifted to engage the low speed clutch connection as shown at Fig. 2. The spring 53 thus exerts greater tension when in the position shown at Fig. 1 than when in the position shown at Fig. 2, but the offset of swivel 59 is such that this greater tension whenjthe high speed engagement is made, only partly o] rcomes the greater resistance of the high speed drive and still permits the clutch connection for this high speed drive to yield responsive to a sudden increase in resistance less than that which will cause yielding of the low speed clutch connection.

At relatively low altitudes the cont 1 rod 52 is actuated so as to shift the countershaft 24 for driving the shaft l8 through the low speed gear train 35-31 as shown at Fig. 2, whereby the impeller 1 is rotated at a relatively slow speed such as will preferably simply mix the combustible charge without forcing it into the cylinders at a pressure appreciably greater than that of the atmosphere. Consequently there is no appreciable supercharging, the engine being sufficiently oversize to maintain the power of the engine constant as altitude increases, by gradually opening the engine throttle. But when an altitude is reached where the density of the air is so reduced that opening the throttle will no longer maintain constant engine power, the rod 52 is actuated so as to shift the shaft 24 for driving the shaft l8 through the high speed gear train 36-418 as shown at Fig. 1. The impeller I1 is thus rotated at relatively high speed, whereby the combustible charge drawn in from the carburetor is forced into the engine cylinders at a pressure higher than that of the surrounding atmosphere, thereby compensating for the lesser density of the air so that with the engine throttle again only partly open the desired engine power may be maintained at the high altitude, with the power then maintained constant as still higher altitudes are reached, by gradually opening the throttle while the supercharger continues to operate.

The invention thus provides for operating the engine without appreciable supercharging at low altitudes where simply the oversize of the engine is sufficient to maintain constant power as the density of the air decreases, but with the supercharger adapted to be brought into operation While the aircraft is in flight and when a higher altitude is reached, whereby the combustible charge is adapted to be forced into the cylinders at a pressure compensating for the lesser density of the air at the higher altitude, so that still higher altitudes may be reached while still maintaining constant engine power. The invention also provides for conveniently manually selecting either the high or the low speed drive for the supercharger, with the driving connection including a yieldable coupling which permits slipp e in the event of sudden strain, and with. the tension of the yieldable coupling readily adjustablewhile the engine is in operation. The improved construction also permits a greater tension to be exerted at the clutch engagement when the high speed drive is operating than when the low speed drive is engaged, but with this greater tension preferably only partly compensating for the greater resistance to high speed drive, so that the high speed clutch engagement will still yield more readily than the low speed engagement, in order to avoid the greater liability of stripping the gears which is inherent to high speed drive.

I claim:

1. In combination, a pair of shafts, a driving connection for one shaft, gear trains of different speed ratio between the-shafts, a gear of each of said gear trains being journaled on one of the shafts, a friction clutch for selectively operatively engaging said gear of the respective gear trains operatively engagin with the last mentioned shaft, means for yieldably tensioning operative engagement of the friction clutch, and means foradiusting the tension- .the clutch comprising cooperating frictional engagement surfaces for each of its operative engagements, means for yieldably tensioning operative engagement of each of the cooperating frictional engagement surfaces, and means for adjusting the tensioning means while the friction clutch is operatively engaged.

3. In combination, a pair of shafts, a. driving connection forv one shaft, gear trains of different speed ratio between the shafts, a gear of each of said gear trains being journaled on one of the shafts, a friction clutch for selectively operatively engaging said gear of the respective gear trains with the last mentioned shaft, means for yieldably tensioning operative engagement of the friction clutch, and a mounting for the tensioning means automatically movable in accordance with selective engagement of the clutch so as to provide different tensioning for the selective operative engagements.

4. In combination, driving connections of different speed ratio, a friction clutch for selectively operatively engaging the respective driving connections, means for yieldably tensioning operative engagement of the friction clutch, and a mounting for the tensioning means automatically movable in accordance with selective engagement of the clutch so as to provide different tensioning for the selective operative engagements.

5. In combination, driving connections of different speed ratio, a friction clutch for selectively operatively engagingthe respective driving connections, means for yieldably tensioning operative engagement of the friction clutch, a mounting for the tensioning means automatically movable in accordance with selective engagement of the clutch so as to provide different tensioning for the selective operative engagements, and means for adjusting the tensioning means while the friction clutch is operatively engaged.

6. In combination, driving connections of different speed ratio, a fri tion clutch for selectively Ogre respective driving connections, means for y eldably tensioning operative engagement of the friction clutch, a mounting for the tensioning means automatically movable in accordance with selective engagement of the clutch so as to provide diiferent tensioning for theselective operative engagements, and means for adjusting said mounting so as to vary the difference in tensioning for the selective operative engagements.

- GLENN D. JOHNSON.

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