US2306372A - Gasoline knock recorder - Google Patents

Description

Dec. 29, 1942. G. B. BANKS GASOLINE KNocK RECORDER Filed March 26, 1940 2 Sheets-Sheet 1 NN \w bh R u R www mm W s.

2 um Nb *w mw uf N\| .QG W MMR hw m SISH u* n l mm Dec. 29, 1942. G. B. BANKS GASOLINE KNOCK RECORDER Filed March 26, 1940 2 Sheets-Sheet 2 Patented Dee. Z9, 1942 puma UNITED STATES PATENT GFFICE GASOLINE KNOCK RECORDER George B. Banks, New Rochelle, N. Y.

Application March 26, 1940, Serial No. 326,091

4 Claims.

This invention relates to recording devices and is an improvement over the recording device forming the subject matter of my copending application, Serial No. 270,419 iiled April 27, 1939.

An object of this invention is to provide an improved recording device for recording the compression values of combustible fuels and recording the compression formed in the cylinder of an internal combustion engine before and after the combustion of the fuel.

Another object of this invention is to provide a recording device of this character which is adapted to be connected to the cylinder of an internal combustion engine and which is o! such a character that the different pressures generated in the combustion chamber of the engine may be accurately and very finely recorded so that the different compressions developed by different combustible fuels may be used as a basis for determining the octane rating of the fuel under test as compared to a fuel having a known octane rating. u n A further object of this invention is to pro-y which fall within the scope of the invention as claimed.

In the drawings:

Figure 1 is a fragmentary ver-tical section of an internal combustion cylinder and a longitudinal section partly broken away and in detail ofvla portion of the device embodying this inventionl- Figure 2 is a diagrammatic view of the electric eircuits'and elements embodying this invention.

lFigure 3 is a detail end elevation of the attachment for the engine shown in Figure 1.

vide a recording device of this character which--" includes the use of electro-magnetic means for# generating electric impulses which are communicated to a stylus operator for actuating the operator in accordance with the amount of elec trie current communicated t0 the operator.

A still further object of this invention is to provide an improved method of recording compression values in an internal combustion engine cylinder, the method embodying the use o! electro-magnetic means actuated by the compression generated in the cylinder of the engine.

Another object of this invention is to provide an indicating and recording device whereby the sudden rise in pressure due to detonation or knock may be clearly indicated and recorded. The method embodies the use of a water cooled by-pass so that the pressure developed during normal explosion will be nearly equally eifective into the secondary coil and by the increase in Figure 4 is a sectional view taken on the line `Eigure 5 asectional view taken on the line 51?-5 ofFigin'e 1.

` Figure fi is a plan view of the recording sheet usedl with this invention.

Referring to the drawings, numeral I0 designates generally an internal combustion engine provided with a cylinder II, having a combustion chamber I2 and a piston I3 which is slidable in the cylinder II. A water jacket Il engages about the cylinder II in the conventional manner and it will be understood that the engine structure I0 is a conventional internal combustion engine and is here shown as one example of an engine with which the hereinafter described invention may be incorporated.

A cylindrical plug I5 is extended through the walls of the water jacket Il and the cylinder Il and is provided with a flange I6 which is adapted to engage the exterior of the jacket Il so as to limit the insertion of the plug I5 within the jacket I4 and the cylinder II. The plug I5 provided with an axial bore I1 within which a tube I8 is fixedly secured. 'I'he plug I5 is adapted to be secured in any suitable manner in the openings I9 and 20 which are formed in the cylinder I I and the jacket I4, respectively, and the tube I8 is adapted to be iixedly mounted in the bore I 'I in any suitable manner. The tube I8 at its outer end projects beyond the outer end of the plug I5 and forms a supporting member for supporting a casing generally designated as 2l. The casing 2| comprises a cylindrical jacket 22, an inner head 23 and an outer head 24. The inner head 23 is provided with a bushing or boss 25 which engages about the projecting end of the tube |8 and is adapted to be secured in any suitable manner such as by threads or the like to the projecting end of the tube I8.

A tubular member 28 extends axially through the head 24 and through the head 23, terminating within the bushing or boss 25. The tube 28 is provided with a lateral passage 21 and th-e head 23 is provided with a radial duct or passage 28 which communicates at one end with the lateral passage 21. The duct 28 is formed by drilling a hole radially of the head 23 and the outer end of the hole is closed by means of a threaded plug 28. The head 24 is provided with a radial duct 38 which communicates with the interior of the tube 28 through a lateral passage 3| formed in the tube 28. A plug 32 is threaded through the jacket or casing 22 into the outer end of the opening or duct 38 so as to close the outer end of this duct.

A connecting tube 34 extends between the two heads 23 and 28 outwardly of the axial tube 28 and is secured at one end in the head 23 and at the opposite end is secured in the head 24 and provides a means establishing communication from the duct 28 to the duct 38.

'I'he Jacket or casing 22 provides a water chamber 35, and an intake pipe 36 is connected at one end to the jacket 35 and at the other end to a source of water supply (not shown).

An outlet or discharge pipe 31 is connected at one end to the jacket or casing 22 diametrically opposite the inlet 38 and as shown in the drawing the outlet 31 may be disposed closely adjacent the head 23 whereas the inlet 38 may be disposed closely adjacent the head 24. A plug 38 is adapted to be threaded into the outer end of the axial tube 28 as shown in Figure 1 so that if desired, the interior ofthe duct 28 may be cleaned by removing the plug 34 and in like manner, the ducts 28 and.

38 may be cleaned by removing the plugs 28 and 33, respectively.

A removable plug 38 is threaded into the wall or head 23 in alignment with one end of the connecting pipe 34 and a second plug 48 is threaded into the head or wall 24 in alignment with the opposite end of the connecting pipe 34. It will, therefore, be seen that the various ducts or passages may be readily cleaned by removing the several plugs so that the operation of the device will not be impaired by accumulation of carbon or other foreign matter in the several ducts.

A primary coil 4| of a transformer generally designated as T in Figure is disposed about the axial pipe 28 and a secondary coil 42 is disposed about the pipe 28 and is spaced from the primary coil 4| by means of an insulated spacing member 43. The coils 4| and 42 are mounted within a cylindrical housing 44 which is provided with heads 45 and 45 so as to seal the two coils 4| and 42 within the water chamber 35. In this manner the water in the chamber 35 will act as a cooling means not only for the coils 4| and 42 but also for the several ducts hereinbefore described.

An insulated plate 41 is disposed in outwardly spaced relation to the outer head 24, being supported in spaced relation to the head 24 by means of a pair of supporting studs 48 which are threaded into the head 24. The insulated plate 41 is fixed to the two studs 48 by fastening devices 48. 'I'he plate 41 is provided with terminals 58 and 5| which are adapted to be connected to the primary spectively. The plate 41 is also provided with a second pair of terminals 84 and 88 which are connected to the secondary coil 42 by conductors 88 and 81, respectively.

The conductors 82, 83, 88 and 81 are extended through the head 24 and preferably the conductors 82, 83, 88 and 81 are extended through a conduit 88 which at one end is mounted in the head 24 and terminates at the outer end of the head 24. 'I'he other end of the conduit 88 is provided with an elbow 88 which is connected to the cylindrical casing 44.

A voltage reducing transformer 88 is provided with a transformer coil 8| which is adapted to be connected by conductors 82 and 88 to a source of alternating current supply of conventional voltage such as -120 volts and the primary 88 also includes a secondary coil 84 which has one side thereof connected as by a conductor 88 to the terminal 88. The other side of the secondary coil 84 is connected by means of a conductor 88 to a rheostat 81. The rheostat 81 is connected by means of a conductor 88 to an ammeter 88 and the ammeter 88 is connected by a conductor 18 to the terminal 8|.

'I'he rheostat 81 is provided for the purpose of transmit-ting the desired amount of electric curlient from the secondary 84 to the primary coil A movable core 1| is slidable within the tube 28, the core 1| being an iron core and preferably the tube 28 is of nom-magnetic material and the core 1| is of a substantially greater length than the length of the coil 4| so that the opposite ends of the core 1| will project beyond the ends oi' the coil 4| as shown in Figure l. In the initial position of the core 1|, theinner end thereof will be in substantial alignment with the outer edge of the lateral passage 21 so that the compression passing through the interior of the tube I8 and the inner portion of the tube 28 will strike the inner end of the core 1| and a portion of the compressed fluid will flow through the lateral passage 21, the duct 28, the pipe 34, the duct 38 and back into the pipe 28 at the opposite end of the core 1|. The force of the compressed uid which may be burned fuel or compressed air, will initially move the core 1| in the direction of the secondary coil 42 so that the electric current in the coil 4| will be transferred to the secondary coil 42, the amount of current transferred from the primary 4| to the secondary 42 being in proportion to the endwise movrznent of the' coil 4| relative to the secondary coil The electric current transferred from the primary coil 4| to the secondary coil 42 by movement of the core 1| will be transmitted to a recording device through conductors 12 and 13 which are connected at one end thereof to the terminals 84 and 55.l The conductor 12 at the opposite end is connected to an electric current amplifying device 14 which is of conventional construction and the conductor 13 at its opposite end is connected to a rectifying device 15 in the form of a copper oxide rectler which is adapted to change the alternating current to direct current. The rectier 18 is connected by means of a conductor 18 to a vacuum tube ammeter 11 which will indicate the amount of electric current passing through the rectifier 15 from the secondary 42.

The ammeter 11 is connected by means of a conductor 18 to the amplifier member 14. 'The amplier 14 is connected by means of a conductor 18 to one side of a source of electric current supply which may be in the form of a battery or other` source of direct current supply and the other side of the current supply source 80 is connected by a conductor 8| to the amplifier 14. The output side of the amplifier 14 is connected by means of a conductor 82 to one end of a solenoid coil 83. The opposite end of the solenoid coil 83 is connected by a conductor 84 to the amplifier 14.

A solenoid core 85 is slidable within the coil 83 and the outer end of the core 85 is provided with a non-magnetic head 86 through which a stylus holder 81 extends. A spring 88 is disposed about the core 85 and at one end bears against the outer end of the coil 83 and at the opposite end bears against the non-magnetic head 86 so as to constantly urge the core 85 outwardly with respect to the coil 83. A stylus 89 is mounted in the holder 81 and is adapted to engage the adjacent surface of a recording sheet 9|) which is provided with a plurality of transversely extended parallel lines 9|. The recording sheet 90 is mounted in a sheet holder or support 92 which is adapted to be moved relative to the stylus 89. The operating means for moving the support 92 may be any conventional operating means and as an example of an operating means therefor reference is had to my copending application, Serial No. 270,419.

In the use and operation of this recording device, a fuel of known octane rating is used as a combustible fuel in the engine I and the pressures generated in the combustion chamber I2 will effect movement of the magnetic core 1|. When the explosion or combustion of the fuel initially occurs, this high pressure will first effect movement of the core 1| and at the same time a portion of the burned gases will' flow from the duct 28 through the connecting tube 34 and the duct 30 to the tube 28 at the outer end of the core 1|. In this manner the gases which engage the Aouter end of the core 1| will act to prevent excessive movement of the core 1| and will serve as a balancing means for the core. However, the pipe 34 is extended through the water chamber 35 so that this pipe is cooled by the water in the chamber 35 and the hot gases passing through the pipe 35 and also through the duct 38 and in the outer portion of the pipe 26 will be cooled by the water in the chamber 34.

In this manner the pressure of the gases on the outer end of the core 1| will be reduced from the pressure of the gases which initially engage the inner end of the core. At the time the engine I0 is started, the rheostat 61 is adjusted so as to provide for the desired amount of current passing to i the primary 4|. The amount of current passing to the primary 4| is adjusted to such a degree that there will be an effective transfer of electric current from the primary 4| to the secondary 42 as the core 1| is shifted endwise in the direction of the secondary 42. The impulses transferred from the primary 4| to the secondary 42 are then communicated through the conductors 12 and 13 to the amplifier 14.

The current transferred from the secondary 42 to the amplifier 14 is increased to a degree sulcient to energize the solenoid coil 83 in order to eiect movement of the core 85. Where fuel of a known octane rating is used, the movement of the core 88 will cause the stylus 89 to form an indication 93 on the record sheet 90. After the known octane rating fuel has operated the engine I8 for a predetermined period, an unknown octane rating fuel is used to operate the engine I0 a higher rating than the known octane rating fuel, the stylus 89 will make an indication 94 on the record sheet 90 which is of a greater length than the indication 93. The rating of the unknown octane rating fuel can then be readily computed by the difference between the indication 93 and the indication 94.

In an auto engine whose top speed is 3600 R. P. M., and of the four cycle type, we have a cylinder firing once every other revolution so even at top speed we would never have more than thirty detonations per second. Detonation is not induced by engine speed, but by the volume charge of fuel ignited. Assume that 3600 R. P. M. of the engine produces maximum car speed of miles per hour. But a motor does not knock at top speed, detonation occurs when we have a large charge of fuel ignited in the cylinder when the car is going about 20 miles per hour, that is, when the car is laboring up a hill or knock occurs only when the motor is delivering full horse power. per hour, then 20 miles per hour represents equals 720 R. P. M. and the maximum detonation frequency would be 72o 360o X30 equals 6 cycles per second. The 60 cycle commercial frequency corresponds to alternations per second. The solenoids of the Ruddell oscillograph respond to frequencies of about 1000 cycles per second. Hence, there is no question as to the magnetic field of my solenoid system responding to a frequency of 6 cycles per second.

The commercial frequency produces a magnetic force in the coil which holds the core in place until detonation occurs in suiicient magnitude to cause the core to break away from the magnetic and Where the unknown octane rating fuel has 75 stop. This magnetic stop principle holds the core in place until detonation pressure occurs, exclusive of any pressure oscillations ahead of detonation wave. I am not concerned with the frequency of the variations of the pressure wave, excepting only the pressure wave due to detonation.

In the actual operation of this knock recorder, the point at which plnking" or knock occurred was clearly shown in relation to the dynarnometer load on the test engine. Under test conditions. I iind that the best engine speed to be 600 R. P. M. Therefore, the frequency set up by detonation is considerably slower than the commercial frequency supply of 60 cycles per second. When operating this meter, the action I have observed is as follows:

The plunger core 1| is forced more or less out of the primary coil 4| into the secondary coil 42, but because of the by-pass 34 pressure the plunger core 1| is balanced by normal explosion pressure and assumes a more or less stationary position and while in this position the plunger core 1|, being magnetized by the current in the primary coil 4|, does set up by transformer action a current in the secondary coil 42. This has been shown by the milliammeter in that circuit. While the by-pass 34 provides a counter pressure against the thrust of normal explosion pressures and prevents violent and rapid movement of the plunger core 1|, causing it to float with a very little movement, when detonation occurs however, the much greater and rapid pressure thrusts the If 3600 R. P. M. corresponds to 100 miles plunger core 1| outward and further into the secondary coil 42 thereby increasing the transformer action and consequent increase of current in the secondary coil 42, as has been shown by the milliammeter in that circuit. The movement of the plunger core H is much greater when subject to detonation pressures, because of the action of the by-pass 34 which prevents more or less any balancing effect on the plunger 1| by reason of the longer travel and cooling of this very short high pressure Wave. This pulsating currentpassed through a conventional type of rectifier and thence through a conventional type of amplifier energizes the stylus coil 83. There is very little movement of the stylus 86 under normal explosion pressure with a decided increase -of movement at the instant detonation occurs. The point at which detonation occurs is determined by reading the dynamometer load when detonation is indicated.

The normal explosion pressure obeys Pascals law" in that this pressure is transmitted so as to act uniformly on all surfaces inside the engine cylinder, hence it acts on the meter core or piston as weil. When detonation occurs the force acting on the cylinder end of the core is increased because of the direct impact of the detonation wave. This higher pressure of detonation does not follow Pascals law but is due to the detonation wave moving in a path which depends upon the mechanics of the combustion process. The detonation phenomena then occurs as a wave of pressure which impacts upon the core and is superimposed upon and adds to the otherwise normal pressure due to normal combustion.

Detonation occurs when the combustion wave is so fast that the unburned remainder of the fuel charge is heated and rapidly compressed to reach a temperature high enough to cause autoignition before the normal combustion process or flame front can reach this unburned portion of the fuel charge.

Under normal .combustion pressure, the gas pressure is conveyed through the by-pass so that it can act upon the back end of the core. Hence under normal combustion conditions there is a differential force acting at the back or outer end of the core to keep the core tight against the magnetic stop. A slight time lag occurs from the time the direct pressure is applied at the front or engine end and the restoring force is effective at the` outer end of the core, due to the length of the by-pass. However, all the time the fuel charge is being compressed, the force differential is increasing so that the back force at the outer end plus the holding force of the magnet is more than enough to offset any increase in force at the front end due to compression of the fuel. Then when normal combustion begins and the pressure rises faster, but still at a definite rate, the differential force also increases at the same rate but at a phase angle that slightly lags the increase in combustion lpressure increase. Thus, at all time during compression or normal combustion due to the fact that Pascals law holds and the time lag through the by-pass is very small, the force opposing any movement of the core holds it in contact with the magnetic stop. This differential force is very important. It is increasing all the time that the engine piston moves up through the compression stroke so that when the sudden pressure increase comes at the beginning of combustion, the differential force can still hold the core against the magnetic stop. This differential force continues to increase as combustion progresses so that even when the maximum pressure of normal combustion is reached, the core is still held tightly against the magnetic stop.

However, as long as only normal combustion obtains, the variable differential force combined with the solenoid force and the magnetic stop is sufficient to prevent any motion of the core so that the core is held against the magnetic stop.

When the high pressure wave oi' detonation occurs, the pressure of the detonation wave impacts upon the front end of the core with such force that the differential force is exceeded and the core snaps away from the magnetic stop. This is because the time lag is greater than the life of the detonation pressure wave. It is important to note that once the core has left the magnetic stop, the magnetic holding force is reduced and continues to decrease as long as the core moves away from the stop.

The fundamental principle of this meter depends upon the fact that the detonation pressure is short-lived, that it is a wave pressure, that it acts on the front surface of the core but is not transmitted through the by-pass to act on the back of the core.

The sudden high detonation pressure exists but for a short time and the core is moved back to contact with the magnetic stop when the detonation force at the front of the core drops to a value less than the differential force due to normal combustion pressure plus the magnetic force due to the solenoid.

This meter then differentiates between normal explosion pressures and detonation wave pressures, in that the core does not move until detonation occurs.

With a recording device of this character, the fuel to be tested is run through the engine i0 and its knock point is registered on the recording sheet 90. The knock point of the fuel under test can be readily varied by blending the desired grade of fuel therewith so that the blended fuel will have the same octane rating as a known octane rating fuel. This recording device has been placed under actual test and has proved that the causes of detonation occur considerably before the detonation or knock becomes audible. This recording device also indicates the knock intensity so that various fuels may be compared as to the time in the movement of the piston i3 at which the knock occurs and the degree of such knock.

Furthermore, by providing a device of this kind wherein the generator for the stylus operator is connected to the stylus operator by means of wires which are properly insulated, the vibrations of the generator caused through its direct connection with the engine cylinder will not be communicated to the stylus operator as is the case where the stylus operator is supported from the actuator therefor.

Through use of the water chamber 35, the heat of the burned gases passing through the duct 28, tube 34, duct 30 and the outer portion of the tube 26 may be finely regulated and the water in the chamber 35 may be maintained at any desired temperature in order to effect the desired dissipation of the pressures of the burned gases on the outer end of the plunger or movable core 1|.

What I claim is:

1. A pressure recording apparatus comprising a tubular member connected at one end to a source of variable iluid pressure supply` primary and secondary transformer coils about a portion of said member, a core slidable in said member and normally held substantially entirely within the magnetic eld of said primary coil, movement of said core in the direction of said secondary coil transferring electric energy from said primary coil to said secondary coil, and a reduced diameter by-pass duct connected to said tubular member at opposite ends oi said core for bypassing a quantity of fluid pressure to the end of the core adjacent said secondary coil whereby to :ushion the movement of said core in one direcion.

2. A pressure recording apparatus comprising a tubular member connected at one end to a source of variable fluid pressure supply, primary and secondary transformer coils about a portion of said member, a core slidable in said member and normally held substantially entirely within the magnetic eld of said primary coil, movement of said core in the direction of said secondary coil transferring electric energy from said primary coil to said secondary coil, ducts connected to said tubular member communicating the fluid pressure to opposite ends of said core, and means for reducing the temperature of the fluid in said ducts to thereby reduce the fluid pressure on said core at the end thereof adjacent said secondary coil whereby to provide a cushioning means for movement of said core in one direction.

3. A pressure recording apparatus comprising a tubular member connected at one end to a source vof variable uid pressure supply, primary and secondary transformer coils about a portion of said member, a core slidable in said member and normally held substantially entirely within the magnetic eld of said primary coil, movement of said core in the direction of said secondary coil transferring electric energy from said primary coil to said secondary coil, a casing about said tubular member and said coils, ducts carried -by said casing communicating with said tubular member on opposite ends of said core, means circulating a cooling medium through said casing to'thereby cool the iiuid in said ducts and reduce the pressure of said fluid on one end of said core.

4. A detonation recording apparatus for an internal combustion engine comprising a pressure actuated movable member, tubular means connected to the engine cylinder and communicating with opposite ends of said member equalizing the pressure on opposite sides thereof under normal compression pressures, electro-magnetic means operatively associated with said member, a second electro-magnetic means operatively associated with said member and said first electromagnetic means, unbalancing of the pressure on one end of said member under detonation pressure effecting movement of said member in one direction to thereby effect a transfer of electric energy from said rst to said second electromagnetic means.

GEORGE B. BANKS.

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