US2127165A

US2127165A - Diesel engine

Info

Publication number: US2127165A
Application number: US106442A
Authority: US
Inventors: Jean J Ehrat
Original assignee: Nordberg Manufacturing Co
Current assignee: Nordberg Manufacturing Co
Priority date: 1936-10-19
Filing date: 1936-10-19
Publication date: 1938-08-16
Anticipated expiration: 1955-08-16

Description

Aug. 16, 1938.

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Filed Oct. 19. 1936 J. J. EHRAT DIESEL ENGINE FU ELPUMPWITH DELIVERY VALVE'.

REMOVED 2 Sheets-Sheet l VC'OMPEESSELD GAS OR, INJECTION AR. LINE,

FUEL LINE.

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Gttornegs Aug, 16, 1938.v -.J J. l-:HRAT

DIESEL ENGINE Filed oct. 19..19se

2 Sheets-Sheet 2 KM@ dm- Gttomegs Patented Aug. 16, 1938 iiNiTE STATES ATENT OFFICE DIESEL ENGINE and .lean J; Ehrat,

Nordberg Manufactu kee, Wis., a corporation of Wisconsin Application October 19,

7 Claims.

es to Diesel engines and for controlling fuel injechas utility in connection gines of the type in which the lift of the air injecis intended chiefly for use according to the methods d in the patents to Nordberg, 10,

1932, and No. 1,962,282, anical control for such enclaimed in Patent No.

1,949,577, March 6, 1934.

Generally stated i5 an ignition charge of by combustible gas under pressure.

into highly compressed air i the cycle involves injecting n the working space fuel oil, which is sprayed The gas serves as the motive fuel, the oil preferably being insuiicient in gine. Regulation is h of gas for each injecti quantity to operate the enad by varying the lift lof sequently the quantity on.

' Because of the small valve lift even at full load, mechanical means for varying the valve lift though entirely operative, are sometimes erratic in action particularly at light loads. In an effort to improve the control characteristics recourse was had to hydraulic actuation. 'I'he hydraulic actuation and control mechanism hereinafter described has been found to have remarkably precise and uniform operating characteristics, and has the commercial advantage that a standard type of Diesel fuel pump can be used (with minor modification) as a major component.

This embodiment wil l now be described in connection with the accompanying drawings, in

Fig. 1 is an end elevation of a Diesel engine embodying the invention.

showing the fuel oil for a single cylinder be actuated by cams on of a portion of Fig. 1

Fig. 3 is a vertical axial section on an enlarged scale through the cylinder head, the fuel injection valve and the hydraulic means for actuating such valve.

Fig. 4 is a. section'on the line 4 4 of Fg.'3.

Fig. 5 is a section on the line 5 5 of Fig. 3.

Fig. 7 is a vertical impulse pump, showin shaft.

Fig. 8 is a perspective 5 of Fig. 7, showing spill Fig. 6 is a section on the line 6-6 of Fig. 3.

axial section through the g its relation to the cam v iew of the pump .plunger back control.

1936, serial No. 106,442 (c1. 12s-s3) Fig. 9 is a fragmentary View similar to a portion of Fig. 7 and showing the check valve used in the fuel pump and omitted from the impulse pump, the two being otherwise similar.

Generally stated the needle valve of the Diesel 5 engine is actuated bya hydraulic plunger to which impulses are delivered by a pump whose delivery is Varied by an adjustable spill back. 'I'he spill back opens to connect the working space of the pump with its -supplypassage at a variable 10 point in each working stroke. Since the pump as here used has no discharge valve, when the spill back opens back flow occurs from the discharge line, and hence from the hydraulic plunger to the intake of the pump. To prevent heating and l5 to stabilize temperature conditions in the discharge line, the latter is water jacketed. Lubricating oil is used as the hydraulic pressure fluid. To guard against accumulation of air in the discharge line, a small quantity of oil is bled each 2O working stroke from the pump discharge to an elevated sump from which the pump intake is fed. Thus the oil is slowly circulated in a closed path and progressive accumulation of air in the discharge line is precluded. Because of the high 25 pressures used and the high operative speed the presence of even small amounts of air in the oil under pressure would have a seriously disturbing e'ect. Most oils carry some occluded air, but if any is freed in the discharge pipe it is carried 30 away by the circulatory flow, so that an objectionable air volume cannot develop even by slow accretion.

Referring rst to Fig. 1, II represents, the base of the engine. I2 represents one of the cylinders, 35 I3 is a cylinderhead, I4 represents the exhaust manifold and I5 the scavenging air manifold. The invention can be applied to either single or multiple cylinder engines of either two or four stroke cyclefit being understood that there be. 40

a separate fuel pump and impulse pump for each cylinder, the various pumps being driven in proper timed relation by suitably spaced cams on asingle cam shaft. Since this involves mereduplication of features of the invention, it is not deemed 45 necessary to illustrate all the cylinders of a multi ple cylinder engine.

The lobe I6 at the left of the crank case is the cam shaft housing and it will be observed that the fuel pumps and impulse pumps are mounted 50 on top of this housing so as to coact with a series of cams `on the cam shaft.

'Ihe device indicated at I0 is a speed governor, here assumed to be of the well known Woodward type. So far as is essential to the present invention, it suffices to point out that in response to en-V gine speed variation the Woodward governor causes the arm I1 to swing angularly.

Referring now to Figs. 1 and 3, there is mounted in the center of head I3, the bonnet I8 of the fuel injection valve. rIhis bonnet includes a tubular housing I9 which extends through the head and seals on a shoulder 20. It is held down by the flange 2| which is retained by the same studs which hold bonnet I8 as clearly shown in Fig. 3.

Mounted within housing I9 is the tubular shell 22 externally grooved as indicated at 23 to permit downward flow of fuel oil between shell 22 and housing I9. A spring 24 holds the shell 22 downward.

The needle Valve generally indicated by the numeral 25 extends freely through shell 22 and seats at 26 in housing |9. Below the seat 26 and held to housing I9 by a sleeve nut clearly shown in Fig. 3 is the nozzle-forming ame plate 21. Housing I9 has a lateral extension 28 to which the gas and oil connections are made, the gas passage being indicated at 29 and the oil passage at 3|) (see Figs. and 6) Oil supplied through passage 30 iiows through grooves 23 to the space immediately above seat 26. When needle valve 25 lifts, combustible gas entering under high pressure through passage 29 flows through shell 22 around the stem of valve 25 and sprays the oil through flame plate 21 into the -working space of the engine. The gas must be under a pressure higher than the compression in the working space and may be supplied by a compressor (not shown) forming part of the engine (as is usual), or by means independent of the engine. All that is required is a source of gas under su'icient pressure.

The stem of .valve 25 passes through a packing gland 3| and carries at its upper end a cross head 32 which is guided for vertical reciprocatory motion in the housing 33. This last is a part of bonnet I8 and is supported thereon by the spaced members 34. An adjustable coil compression spring 35 urges cross head 32 downward, i. e. in a valve closing direction.

The parts so far described do not differ markedly from valves heretofore used in air injection Diesel engines.

A bifurcated lever 36 is pivoted at 31 on the upstanding members 34 and carries two cylindrical thrust blocks 38 which underlie a hardened steel thrust ring 39 xed on stem of valve 25. To operate the lever 36, and consequently the valve 2,5, a pressure motor, whose cylinder is generally indicated at 4|, is mounted on the cylinder head I3. Slidable in the cylinder 4| is a free plunger 42 which is subject on its lower end to hydraulic pressure communicated through the connection 43. The plunger 42 is circumferentially grooved to minimize leakage and is in thrust engagement at its upper end with a push rod 44 which engages a roller 45 on the lever 36. A coil tension spring 46 draws the lever 36 downward. Mounted near the lower end of the cylinder 4| is a choke or bleed fitting 41 which is held in place by the screw plug 48. This choke fitting permits very slow flow from the upper end of the passage 43 to'a pipe 49 which leads to the elevated sump 5| (see Fig. 1). This sump furnishes the oil to the hydraulic pressure system by way of valve 52 and pipe 53 and serves also as a gas separation chamber. 'I'he elbow 54 is a drain connection for such oil as may leak past the piston 42 and push rod 44. It may be piped to any suitable point, such drain piping not being shown in the drawings.

To develop timed pressure impulses to actuate the piston 42, use is made of a pump essentially identical with the fuel injecting pumps commonly used in Diesel engines. It comprises a spill back measuring pump here shown as of the type manufactured by the United American Bosch Corporation. Its construction is indicated in Figs. k7 and 8.

In Figure 7, 55 represents the engine cam shaft which in a two cycle engine would be driven at crank shaft speed and in a four vcycle engine 4would be driven at half crank shaft speed. Shaft 55 carries a cam 56 in thrust engagement with the roller 51 carried by the cross head 58. The spring 59 forces the cross head downward and the key and spline 6| hold it against rotation. The element 62 acts as a combined spring seat and diverter for any oil which might leak downwardly from the fuel pump. A drain connection (not shown) is provided for such oil. Where the pump is handling lubricating oil such diversion is not particularly important.

The stem 63 of the cross against the cup-shaped cross head 64 of the fuel pump, generally indicated at 60. The stem carries an umbrella-like cap to direct oil to diverter 62. Cross head 64 is urged downward by a spring which is indicated at 65. The spring reacts upon a disk 66 which embraces a head formed on the lower end of the pump plunger 61. The plunger 61 works in a fixed bushing or sleeve 68 which has an inlet port 69, and on the opposite side a spill back port 10. The plunger 61 has a recess 1| provided with one spiral margin 12, so formed that rotation of the plunger on its longitudinal axis will vary the time in the working stroke at which the working space 13 above the plunger 61 is connected through recess 1| withthe spill back port 10. As the plunger 61 moves upward, it first displaces oil from the working space through the pipe connection 14 to the passage 43, heretofore described and then opens the spill back port to the intake.

The pipe 14 is jacketed as indicated at 15, there being inlet anddischarge cooling water connections, one of which appears at 16 in Fig. 3, and the other of which appears at 11 in Fig. '1. The purpose of this is to establish stable temperature conditions in the outlet, and prevent the development of heat therein. The piston displacements are small, the pressures are high, and ow through the connecting passages is rather rapid. While the water jacket may not be necessary in head reacts in thrust .all cases, it is considered a desirable adjunct.

The hydraulic liquid, conveniently lubricating oil, is brought to the supply passage 69 from the elevated sump 52 by way of pipe 53 which is connected to the pump as indicated at 18. To rotate the vplunger 61 and thus change the point in the working stroke at which the spill back commences a rotary sleeve 19 bifurcated at its lower end is provided. The bifurcated lower end straddles the cross plate 8| fast on theplunger stem, permitting reciprocation of the plunger but controlling its angular position. The sleeve 19 is angularly adjusted by the toothed sector 82 which meshes with rack teeth on a bar 83 slidably mounted in the body of the pump.

Referring now to Fig. 1, the bar 83 is connected by bell crank 84 and link 85 with the arm |1 on the governor. In a multi-cylinder engine the bell crank 84 would be part of a rock shaft extending along the engine and connected similarly to the adjusting rods of all the impulse units, of which there would be one for each cylinder.

As the governor responds to increasing speed it moves the arm il and the rod 83 in a direction to hasten the spill back and thus reduce the lift of the needle valve 25. v

It is necessary to supply fuel oil through the connection 30 to the needle valve. To perform this function a second pump, substantially identical with that shown in Fig. '7, is used. 'I'his pump is indicated in Fig. 2 at 86. It may have and conveniently would have an adjusting member 8l, but this adjusting member is not operated by the governor. On the contrary it is manually set and then locked in position. The pump 86 delivers fuel oil through the pipe 88 to the connection 30.

Unlike the impulse device shown in Fig. 7 the fuel pump 86 has above the Working space' of the pump and between it and the pipe 88, a combined check valve and anti-dribbling device 88 characteristic of the Bosch fuel feed pump and for which no novelty is here claimed. The device 89 consists essentially of a check valve attached to a small piston beneath it, the piston being provided With bypass grooves. A compression spring 9i urges the valve toward its seat, preventing'back .-flow of the oil that has been discharged on the working stroke. This valve and v spring are omitted from the impulse unit, as indicated in Fig. 7, because back flow is an important factor in the use of the pump as an impulse device.

The operation of the mechanism can now be traced. The cam which operates the fuel pump 86 is so timed that it will complete delivery of a measured quantity of oil to the space above seat of needle valve 25, shortly before the lift of the valve commences. The cam which operates the plunger in the impulse device 60 is properly timed with reference to the desired time of lift of the needle valve 25. It is given the usual slight lead with reference to the head end dead point of the engine piston and a slight additional lead to compensate for a lag factor in the response of the piston 42. 'Ihe lag is slight and has been found to be so nearly uniform as to introduce no material disturbing factor` It is present, however, and should be compensated for.

When the piston 6l descends it draws in oil fed through the connection 53 and port 68. On its ensuing upward stroke it displaces this oil through the pipe lil, and this oil arriving through the port i3 forces the piston 42 upward and lifts the needle valve 25. 'I'his action continues until the spill back port opens, the point of opening ybeing determined by the angular position of the piston 61 as already described. As soon as the spill back port i opens back flow occurs from the space below the ply connection I8 and pipe 53.

piston 132 through the port 43 and pipe lid Aand thence through the spill back port il to the sup- It follows that the prime purpose of the plunger 6l is to deliver an impulse to the 'piston i2 through oil under pressure and then dissipate this pressure at some chosen point in the Workingstroke of the plunger 67, causing descent of the piston l2 and the related needle valve 25. The governor controls the duration of the lift impulse. serves each stroke to bleed from the upper end of the connection lll, i3 ``a`\minute quantity of oil. Any air occluded in the oil would tend to accumulate near the upper end of this connection, and the function of the bleed port is to dissipate this air as it i's freed and prevent its accumulation. In consequence there is a minute continuous circulation of oil in a closed circuit but the major portion of the oil flow is reversed in each cycle.

The device has been found to give precise tim- The leak port il means for varying the point in ing and a smoothly graduated regulation of lift throughout the entire load vrange of the engine. Some idea of the precision required can be gained from the fact that in tests with a three cylinder 17 by 25" Diesel engine, using this type of fuel control, the valve lift never exceeded 0.044 and the minimum of lift was of the order. of 0.008". 'Ihe improvementin regulation as compared to a strictly mechanical control of the lift was noticeable throughout the load range and particularly noticeable in the low load ranges in which small lifts are encountered.

In certain types of air injection Diesel engines control of the lift of the needle valve enters into the engine regulation. In such engines the hydraulic variable lift needle valve actuating mecha`nism herein disclosed would be useful.

While I have shown one particular commercial type of spill back valve, and prefer it, .other types are known, and might be substituted without departure from the spirit of the invention. In certain cases it may not -be necessary to use the bleed port 4l. Its omission involves no material change in operative principle. The Water jacket 'l5 on the pressure pipe may also be omitted Without change of principle. Various other changes within the spirit of the invention may be made by the exercise of mechanical skill, and the possibility of maln'ng such changes is contemplated.

What is claimed is:-

l. The combination with an lengine of the Diesel type having a working space; of a nozzle for injecting fuel into said space; a normally closed valve controlling iiow through said nozzle; means for supplying charges of liquid fuel to said nozzle in advance of said valve; means for supplying gas under pressure to said nozzle in advance of said valve; a hydraulic pressure motor for opening said valve; and means for delivering timed pressure impulses to said motor and comprising a reciprocating displacement plunger device driven in timed relation by said engine and having a liquid intake and a spill back opened to said intake at a point in the displacement stroke of said plunger.

2. The combination with an engine of the Diesel type having a Working space; of :i nozzle for injecting fuel into said space; a normally closed valve controlling iiow through said nozzle; means for supplying charges of liquid fuel to said nozzle in advance of said valve; means for supplying gas under pressure to said nozzle in advance of said valve; a hydraulic pressure motor for opening said valve; means for delivering timed pressure impulses to said motor vand comprising a reciprocating displacement plunger device driven in timed relation by said engine and having a liquid intake and a spill back open to said intake at a point in the displacement stroke of said plunger; and means for varying the point in the displace'- ment stroke at which said spill back opens.

3. The combination with an engine of the Diesel type having a working space; of a nozzle for injecting fuel into said space; a normally closed valve controlling flow through said nozzle; means for supplying charges of liquid fuel to said nozzle in advance of said valve; means for supplying gas under pressure to said nozzle in advance of said valve; a hydraulic pressure motor for opening said valve; means for delivering timed pressure impulses to said motor and comprising a reciproeating displacement plunger device driven in timed relation by said engine and having a liquid intake and a spill back opened to said intake at a point in the displacement stroke of said plunger;

the displacement stroke at which said spill back opens; and a governor responsive to engine speed connected to control the last named means.

4. The combination with an engine of the Diesel type having a working space; of a nozzle for injecting fuel into said space; a normally closed valve controlling flow through said nozzle; means for supplying charges of liquid fuel to said nozzle in advance of said valve; means for supplying gas under pressure to said nozzle in advance of said valve; a hydraulic pressure motor for opening said Valve; impulse means connected to deliver fluid pressure impulses to said motor and comprising reciprocating plunger and coacting cylinder provided with a liquid intake and interacting spill-backmeans for returning liquid to said intake', the time of opening of said spill-back means in each working stroke being controlled by the relative angular positions of the plunger and cylinder; and means for varying such angular position.

5. The combination with an engine of the Diesel type having a working space; of a nozzle for injecting fuel into said space; a normallyA closed valve controlling ilow through said nozzle; means for supplying charges of liquid fuel to said nozzle in advance of said valve; means for supplying gas under pressure to said nozzle in advance of said valve; a hydraulic pressure motor for opening said valve; impulse means connected to deliver fluid pressure impulses to said motor and comprising reciprocating plunger and coacting cylinder provided with a liquid intake and interacting spillback means for returning liquid to said intake, the time of opening of said spill-back means in each working stroke being controlled by the relative angular positions of the plunger and cylinder; means for varying such angular position; and a governor responsive to engine speed and connected to actuate the last-named means.

6. In a Diesel `engine the combination of fuel injecting valve; a hydraulic pressure motor for actuating said valve; means driven by said engine for developing hydraulic pressure impulses in timed relation to the operation of the engine; means for confining a liquid through which said impulses are transmitted to said motor; and means for regulating the temperature of said liquid.

7. In a Diesel engine the combination of fuel injecting valve; a hydraulic pressure motor for actuating said valve; means driven by said engine for developing hydraulic pressure impulses in timed relation to the operation of the engine; means for confining a liquid through which said impulses are transmitted to said motor; and a cooling jacket for controlling thek temperature of said liquid.

- JEAN J. EHRAT.