US2251976A - Indicator for internal combustion engines - Google Patents

Description

Aug. 12,1941. G. w. BROWN INDICATOR FOR INTERNAL CQMBUSTION ENGINES Filed Dec. 14, 1939 g I I l I ll IND T I I l I l I l ll Patented Aug. 12, 1941 INDICATOR FOR INTERNAL COMBUSTION ENGINES Gilman W. Brown, Danvers, Mass, assigncr of one-half to Charles H. Endee, Milton, Mass.

Application December 14, 1939, Serial No. 309,304

2 Claims.

This invention relates to indicators for internal combustion engines, especially high speed engines. These indicators form diagrams or graphs showing the relation of the varying pressures in an engine cylinder to the position of the piston in the cylinder. The efliciency of the engine may then be readily determined from an analysis of these graphs.

Indicators of this type now known to the art are inefficient and fail to record the pressures accurately, especially when forced to record at very high speeds. This is largely due to excessive friction and errors caused by inertia and momentum.

It is the object of this invention to provide an accurate indicator capable of responding instantly to changes of pressure and to provide greater precision in the diagram.

The invention will be best understood from the following description in conjunction with the accompanying drawing. It is to be understood that the invention is not limited to the details of construction and arrangement of parts illustrated in the drawing, since the invention as defined by the claims hereinafter appended, may be otherwise embodied without departure from the spirit and scope thereof.

It is also to be understood that the terms here used are for the purpose of description and not of limitation, and it is not intended to limit the invention claimed herein beyond the requirements of the prior art.

In the drawing:

Fig. 1 is a view partly in longitudinal section of a device embodying my invention.

Fig. 2 is a cross-sectional view on the line 2-2 of Fig. 1.

Fig. 3 is a view in cross section on the line 3-4 of Fig. 1.

Fig. 4 is a view in longitudinal section on the line 4-4 of Fig. 2.

Fig. 5 is a cross-sectional view on the line 5-5 of Fig. 1.

Fig. 6 is a View in cross section on the line 6-45 of Fig. l.

Fig. 7 is a diagrammatic view showing the relative position of the vents and intake ports and the parts of the rotor and stator.

The device herein described may be considered as having three major parts. There is a pressure responsive mechanism, a recording mechanism, and a coordinated drive mechanism. In the drawing, the pressure responsive mechanism is generally denoted by the letter A, the recording mechanism by the letter B, and the coordinated drive mechanism by the letter C. These various structures are positioned and supported by a frame generally denoted by the letter D. The pressure responsive mechanism A comprises a head portion E and a tube portion F.

The head portion E contains a stationary tube or hollow cylindrical stator I. A rotor or pressure responsive body 2 mounted in the stator I comprises a small tube or hollow shaft 3 journalled in and extending through the head E and the stator I and bearing two diametrically opposite vanes t and 5 which extend radially from the tube 2 to the inner surface of the stator I. The stator I is also provided with diametrically opposed partitions 6 and I extending from the inner surface thereof to the outer surface of the hub of the rotor 2. The partitions 6 and I divide the space within the stator into two substantially equal portions which are again divided, but not necessarily equally, by the vanes of the rotor. Thus, when the rotor is in its normal or usual position before pressure is applied as shown in Figs. 2 and 3, vane 3 of the rotor is preferably quite near partition 6 of the stator and consequently vane 5 of the rotor is quite near partition 'I of the stator. A gas inlet head 8 is secured to the head portion E as by cap screws 9. The head 8 is a disk-like member completely enclosing one end of the hollow cylindrical stator I, the other end of which is enclosed by the head portion E. The outer face of the head 8 is provided with a hollow projection having a substantially semicircular portion communicating with inlet ports I3 and I4 and also having a threaded stem portion which is connected to a conduit II] (Fig. 2). A valve II having a handle I2 is interposed in the conduit E8. The other end of the conduit I0 is connected to the cylinder of an engine (not shown) in such manner that the gases in the cylinder are permitted to enter the conduit. Intake ports I3 and I4 in the inlet head 8 permit the passage of gas in equal portions and under equal pressures from the conduit ID to the spaces between the adjacent vanes and partitions of the rotor and stator. These spaces should be quite small, and need be only large enough to admit pressure to the vanes of the rotor. The rotor is stationary when pressure is first admitted; the movement of the rotor is, therefore, positively and precisely determined by the extent of the pressure. The slightest pressure admitted to the rotor at any time is instantly effective. There are no large spaces which. allow the pressure to lag, accumulate or become dispersed. The rotor is instantly responsive because it is very light and is balanced during rotation. The minimum of moving parts avoids friction and momentum. The spaces between parts 4 and 'l and between 5 and 6 are provided with vents l5 and it which insure the absence of back pressure against the vanes of the rotor during movement under pressure, since these spaces are always subject to atmospheric pressure. An annular channel I? is formed in the head portion E and provided with an inlet 58 and an outlet IS. The head E thus constitutes a water-jacket which permits cold water to be circulated about the rotor and stator to prevent overheating.

The tube portion F is provided with an inner tube 23 which is fixed in relation to the head portion E, and an outer tube or sleeve 2i capale of rotative movement about the tube 29. The

tube 3 of the rotor extends a short distance into the chamber formed by tube 20 and is there firmly secured to a flat spring 22 in such manner that relative rotation is not permitted. The flat spring 22 passes through a narrow slot 23 formed in the mid section of a sliding block 24. Lugs 25 and 25 on the block 24 project into longitudinally extending grooves 21 and 28 formed in the walls of the inner tube 20 thus preventing rotation of the block. Rotation of the tube 2 creates torsion in the spring 22, and the length of the spring subject to torsion is determined by the position of the sliding block 24; the nearer the block approaches the tube 3, the shorter the extent of the spring which may be twisted and the greater the resistance to rotation of the rotor. A longitudinally extending aperture or slot 29 in the inner tube 25 gives access to the block 24 and permits it to be slid longitudinally of the spring. A longitudinally extending aperture or slot 3! is also formed in the outer tube 2! thus permitting access to the slot in the tube 28 when tube 25 is rotated about tube 25 until the aperture in tube 2| is in juxtaposition with the aperture in tube 29. A scale 35 may be formed on the outer tube 2| along the edge of the slot 3! to indicate the resistance of the spring for various positions of the block. Further rotation of tube 2% causes it to seal the opening 29 in tube 29. An extension 32 forms an inlet for admitting cooling air or gas to the chamber formed by the tube 26. Cool air or gas thus admitted tends to keep the spring 22 at an even temperature, and passes through tube 3 of the rotor thus cooling the rotor and adjacent parts and prevents transmission of heat to the recording mechanism. Ports 33 located in the tube 3 immediately beyond the inlet head 3 permit the escape of these cooling gases and serve to insulate the extreme end of the tube 3 which becomes part of the recording mechanism B. A plug 67 in this extreme end of the tube 3 prevents the gases from entering the recording mechanism.

The recording mechanism B is provided with a tube 34 into which extends the rotor tube 3. A concave mirror 68 is located in the opposite end of the tube 34, and a source of light 35 is placed in front of the mirror. Light from this source passes through lenses and 31 which cause the light beams to converge on a concave mirror 38 mounted on the end of the tube 3. The light beams so reflected pass through a hood 39 to a light sensitive film 48 held by a support 4! slidably mounted in a portion of the frame D. A shield 45a protects the film when not in use.

The drive mechanism C is designed to give the film support 4! a limited reciprocating movement in timed relation to the movement of a piston (not shown) of the engine being tested in order to obtain a proper diagram. In this drive mechanism, a disc crank 42 is driven at engine shaft speed by the engine being tested, and transmits a reciprocating motion to support 41 through a telescoping connecting rod which comprises a rod 43 and sleeve 44 capable of relative movement when no recording is being made. An eccentric of the same throw may be used in place of the crank, if preferred. The sleeve 44 is provided with springs 45 and 46 having teeth 47 and 43. The sleeve 44 is also provided with a cam sleeve or ring 49 having cam surfaces and 5! (see Fig. 6). The cam ring 49 also has a projecting arm 52 adapted to engage a cam bar 53 pivotally mounted on a portion of the frame D. The cam bar or throw-out bar 53 is normally held in operative position by a spring 5%. A lateral extension of this bar forms a handle 55. When the cam bar is in operative position as shown in Figs. 1 and 6, the arm 52 is deflected, thereby rotating the cam ring and causing the cam surfaces 50 and 5! to spread the springs 45 and 45, thus preventing teeth 41 and 48 from engaging the rod 43. When the handle 55 is depressed, allowing the arm 52 and cam ring 45 to assume the position shown in dotted lines in Fig. 6 under the impulse of a spring 56, in which the cam surfaces 59 and El no longer engage springs 45 and 4E. Thereupon teeth 41 and 45 drop through apertures 51 and 58 in the sleeve 44 and come to rest in notches 59 and 6D in rod 43, thus locking the rod 43 and sleeve 44 and causing the rotative movement of the disc crank 42 to be transmitted as a reciprocative movement of the film support 4|. A vent 6| in the sleeve 44 prevents back pressure against the rod 43. The rod 43 and sleeve 44 will remain locked together and reciprocation of the support 41 will continue only while the handle 55 is depressed. When the handle 55 is released, the cams 53 and 5! will engage the springs and 45 at the end of the stroke and release the connection between the rod 43 and sleeve 44.

In operation, gas from the engine cylinder under examination is admitted to the conduit Hi. When the valve II is opened, the pressure of the gas in the cylinder is transmitted equally through the two-port inlet head 8 to corresponding surfaces of the opposite rotor vanes, causing a slight rotative movement of the rotor. There is no back pressure or increased resistance to this movement, since the spaces into which the vanes move are subject to atmospheric pressure because of the presence of vents l5 and 16. Since both vanes of the rotor and opposite sides of the rotor body are subjected to equal pressures, the body of the rotor is held in balance, and there is no pressure or weight on the journals to cause friction, so that the rotor is substantially balanced during operation, and inertia and momentum are not allowed to interfere with the accuracy of the diagrams.

When it is said that equal pressures are applied to opposite sides of the rotor, this means that pressures derived from the engine cylinder are introduced equally into the chamber defined by vane 4 and partition 6 and the chamber defined by vane 5 and partition 1.

The movement of the rotor is resisted by the is pressed downwardly the bar 53' fiat steel spring 22 firmly fixed to one end of the tube 3, and the degree of resistance is determined by the position of the sliding block 24. The concave mirror 38 on the other end of the tube 3 reflects concentrated beams of light from the lamp 35 to the light sensitive film 46, and also serves to further concentrate the beams. When the film is reciprocated horizontally at engine shaft speed the variation in cylinder pressure is transmitted as a variation in rot'ative movement of the rotor and as a variation in the position of the light beam in a plane perpendicular to the horizontal plane in which the film moves. Since the film is moved in timed relation to the piston of the engine, a graph is v.

formed on the film which shows the relation of pressure to piston position, from which the ciliciency is determined.

I claim:

1. An apparatus for indicating and recording the gas pressure in an engine during operation having a record sheet, means for moving the record sheet in timed relation to the movement of the engine piston, pressure responsive means, and means for producing a representation on said record sheet of the movement of said pressure responsive means, said apparatus being characterized by pressure responsive means having a casing providing a cylinder, a rotor within said cylinder having its axle rotatably mounted in said casing, a straight flat spring secured at one end to said axle and projecting axially therefrom, and means mounted for adjustment lengthwise of said spring and adapted to hold the latter rigid at a position spaced from said axle.

2. An apparatus for indicating and recording the gas pressure in an engine during operation having a record sheet, means for moving the record sheet in timed relation to the movement of the engine piston, pressure responsive means, and means for producing a representation on said record sheet of the movement of said pressure responsive means, said apparatus being characterized by pressure responsive means having a casing providing a cylinder, a tube mounted for rotation in said casing and extending through said cylinder and easing with its axis aligned with the ads of said cylinder, a rotor within said cylinder carried by said tube, a straight fiat spring secured at one end to said tube and projecting axially thereof, means mounted for adjustment lengthwise of said spring and adapted to hold the latter rigid at a position spaced from said tube.

GILMAN W. BROWN.

Images