US2019103A - Pump - Google Patents

Description

Oat. 29,- 1935. E. o. P. THEGE PUMP Filed Jan. 9, 1933 2 Sheets-Sheet 1 iA/VdA/TOR Oct. 29, 1935. E. o. P. THEGE PUMP Filed Jan. 9, 1933 2 Sheets-sheaf 2 Patented Oct. 29, 1635 PUMP . Edvin Ossian Parcival Thege, Stockholm, Sweden, assignor to Aktiebolaget Atlas Diesel, Stock-, hohn, Sweden, a corporation of Sweden Application January 9, 1933, Serial No.- 650,943

In Sweden July 11, 1932 6 Claims. (01. 103-41) The present invention relates to pumps and has particular reference to adjustable fuelpumps for internal combustion engines of the solid injection type. The invention is particularly applicable to engines of the type in which governing is effected by varying the length of the effective discharge stroke of the'pump and discharging superfluous fuel from the pump chamber through a pump release valve.

Broadly speakingthe general object of the invention may be said to be to improve upon prior forms of pump construction of the kind employing plunger actuated release valve structure.

The manner in which this general object, and

other and more detailed objects and advantages of the invention which will hereafter be pointed out, are attained may best be understood by reference to the ensuing description of suitable forms of pump construction for carrying'the invention .0 into efiect. In the accompanying drawings forming'a part of this specification, Fig. 1 is a vertical transverse section through a fuel pump embodying the invention;

' 2 Fig. 2 is a transverse section taken on the line a 22 of Fig.1; and Fig. '3 is a section similar to Fig. 1 showing another form of pump embodying the invention. Referring now to the pump shown in Figs. 1 and 2, reference numeral I indicates a main frame or body of the pump. The pump shaft 2 is pro-; vided with a cam 3 acting on a lever 6 pivoted about a pin or shaft 4 and provided with a roller 5 for transmitting motion to the plunger element of the pump. Roller 5 acts upon a tappet I, re-

ciprocably mounted in a guide 8 and restrained against rotational movement by a key 9 engaging asuitable key-.way in the guide 8. The 'tappet 'l is forced downwardly by a spring l0 inserted between a portion of the pump body and. a flange II on the tappet. Spring Ill acts to cause the roller 5 and tappetl to follow the contour of the cam 3.

' The upper, portion of the tappet I is provided with a recess having internal threads l2 engaged by external threads |3 on a plunger I reciprocable in a pump cylinder l5 inserted in the body of the;pump and providing the working bore of the pump.",

A gear I6 is mounted around-thetcylinder 15,

the gearbeing rotatable with respect to the cylinder and fixed axially with respect to the. cylinder. Two arms I I! attached to the gear project downwardly therefrom and pass respectively be-' Q tween two lateral projections It! on the plunger- 14. The arms l'I have relative axial movement with respect to the projections l8 and act to cause plunger H to rotate with gear l6 when the latter is turned. A rack I9 is reciprocably mounted in a transverse guide provided in the 5 pump body and meshes with gear l6. Rack i9 is adapted to be shifted by an engine gov-' ernor or other control means through suitable motion transmitting mechanism so that if the load on the engine is increased the governor rotates the gear l6, and with it the plunger M, in a direction such thatthe compound plunger, formed by members 1 and I4, is shortened. Conversely, if the load on the engine is reduced, the length of the compound plunger-is increased.

An annular member 50 is mounted in the pump body I above the pump cylinder l5 and the lower end of this member cooperates with the upper end of the pump cylinder to form the pump 'chamber 20 of the pump. The pump 20; chamber 20 is placed in communication with an upper chamber 22 by means of channels including a series of passages 2| formed in and extending longitudinally through the member 50.- Member v 50 isrtained in position by a part 51, recessed 25 to provide the upper chamber 22 and forming the seat for the spring loaded delivery valve 23. Fuel delivered to the chamber. 22 on the working stroke of the pump flows past the delivery, valve 23 to the outlet 24 adapted tobe connected to a device for injecting fuel to an engine eylinder.

The upper end of the bore of the annular member 50 provides a seat for the pump suction valve.

- 25 which is urged toward closed position by the valve spring 26. Fuel is supplied to the pump through the inlet conduit 21 in the pump body and passes therefromthrough a series of 'trans-. verse passages 28 extending laterally through the wall of the annular member 50. As will be cb- 0 served from the. drawings, these laterally ex--v tending passages provide communication between the fuel supply for the'pump and the inlet side of the inlet valve.

In the embodiment illustrated, valve 25 is annu- 45 lar," having a central longitudinal bore in which is mounted the plunger portion ofa release valve 29. The lower part of this plunger portion of the valve is tapered and engages a seat 30 formed in .the lower portion of the annularmember mm A part of the release valve 29, in the form. of i a pin, projects downwardly into the pump chamber 20 in a positionto be contacted by the inner end" of the plunger during its working stroke. The releasevalve is urged toward its seat by spring 3| 55 PIA-TENT OFFICE transverse passages 32' through the side wall valve seat provide communication between the outlet side of the release valve and a channel 33 in the pump body which is in open communication with the fuel supply.

The operation ofthe pump is as follows. During the suction stroke of the plunger under, the influence of spring l0, fuel is drawn into the pump chamber through the transverse passages 28, valve 25 and the longitudinally extending passages 2| in the member 50. On the return or working. stroke, effected by the action of the cam 3, the plunger forces fuel from the chamber 20 through the passages fl, past the closed suction valve 25, and

into the upper chamber 22. The fuel further flows through the delivery valve 23 and the outlet 24 to the fuel injection device 01' the engine. Before reaching the end of its working or discharge stroke, the plunger I4 strikes the pin projecting into the pump chamber to open the release valve W 29. After the release valve is opened, the superfluous fuel displaced by further movement of the pump plunger during the latter part of its discharge stroke, ,is returned to the fuel supply by way of the transverse passages in the mem-' ber 59.

The opening of the release valve may be said to determine the end of the effective discharge stroke of the pump and the time at which liquid is released from the pump chamber to terminate the effective discharge stroke is varied by altering the length of the compound pump plunger formed by the parts I and it. Alterationof the length of the pump plunger is accomplished by movement'of rack IS and consequent rotation of the gear l6. Movement of the gear turns the plunger part It to a higher or lower position in the tappett'i and consequentlt causes the inner end oi the plunger I4 to open the release valve at an earlier-or later time, as the case may be, in the cycle of operation of the pump. Earlier opening of the releasevalve results in less fuel being supplied per working stroke of the pump and later opening of the release valve results in a greater quantity of fuel being supplied per working stroke.

In order to reduce the shock of contact between the plunger and the release valve pin, the upper end of the plunger may advantageously be provided with a cavity 39 which is 'fllled with liquid whichmust be displaced as'the two parts come into contact.

The high l iquid pressure existing in the chamber during the discharge stroke of the pump and reacting against the inner end of the plunger H, tends to cause the plunger to turn with respect to the tappet I in a direction shortening the length of the compound plunger. This tendency of the plunger to turn under the mfluencepr the closed suctionyalve to the chamber 22 from pressure from the pump chamber would, if not counteracted, place an undesirable load on the 20 from the supply conduit 21,

acted to screw the plunger ll downwardly to shorten the length of the pump plunger.

In order to substantially eliminate the influence of pump chamber pressure on the governing means, the lower portion of the plunger I l is advantageously made hollow and a closely fitting plug orpiston '35 is mounted therein with its. lower end resting on the bottom of the recess in the tappet I. A spring 36 above the plug 35 serves to hold the latter in contact withthe tappet 1. A channel 31, passing through the plunger I4, provides communication between the chamber in the lower' end of the plunger l4 and the pump chamber 20. As will be observed from the drawing s; the cross sectional area of this lower chamber is substantially equalto the cross sectional area of the end of the plunger ll which is exposed to pump chamber pressure and it will be evident from this that during the working stroke of the pump, the plunger I 4 will be substantially balanced against end pressure imposed by the pressure of liquid in the pump chamber. Consequently, the position of plunger I4 relative to the tappet I may be shifted by the applicationof very-* little force to the rack- I The balancing feature of' the pump plunger construction hereinabove described is not per se a part of the present invention and forms the claimed subject matter of U. S. Patent 1,989,720, granted February '5, 1935, on an application filed by me January 9, 1933.

Referring now to Fig. 3, the bonstruction of the form of pump shown therein is in general the same as that previously described in connection with Fig. 1. In the present form of construction however, a combined suction and release valve is provided comprising a. valve head 38 having a plunger like extension fitting in the bore of the annular member 500. and projecting into the pump chamber to be contacted by the end of the pump plunger it. As in the embodiment shown in'Fig. l, the pump member 5011. is provided with a series of longitudinally extending passages 2| providing communication between the pump chamber 20 and the upper chamber 22;. the latter being in communication with the delivery valve 23 and outlet passage 28. The fuel supply chanhe] 21 is placed in communication with the inlet side of the suction valve 38 by means of a series of transverse passages 28 extending through the side wall of the annular member 5011 and passages 32a are also formed in member a, the

latter passages providing communication with the which it passes through .the delivery valve to the outlet channel 24.. The efiective discharge stroke plunger I 4 with the which now acts; as a release valve to permit excess liquid-displaced by the pump plunger to flow back to the liquid supply through the passages 28 and 32a. I a

By constructing the pump in .the manner hereinbeforedescribed, numerous practical advantages of considerable importance are ,obtained; By arranging the suction and release valve strucis terminated by contact of the inner end of the j part 39 of the suction valve 1 Y ao'iaios ture and the necessary suction, discharge and release valve passages in a separate pump member, and further, by providing a separate pump cylinder, it is possible to make the pump body of cast material of relatively low strength and to relieve the body of the extremely high pressures developed in a fuel injection pump. The construction lends itself to accurate and relatively inexpensive manufacture of those parts of the pump structure which require accuracy of dlmensions and since such parts may be made separately of material suitable for withstanding the high pressures encountered, it will be evident that the cost of manufacture of the pump may be very.

of example and it is to be understood that the invention embraces all forms of apparatus falling within the scope of the appended claims.-

I claim:

1. In a reciprocating pump having a working bore, a pump body, means providing a pump chamber at one end of said bore including a member mounted in said body, a pump plunger working in said bore, valve means mounted in said member for admitting liquid to said chamber and for releasing liquid therefrom including a part arranged to be contacted by one end of the plunger on its discharge stroke to effect release of liquid from said chamber, and a pump delivery valve, said member having passages formed therein for placing said valve means in communication with the pump chamber and with the liquid supply for the pump and for placing the pump chamber in communication with the pump delivery valve.

2. In a reciprocating pump having a working bore: a pump body, means providing a pump chamber at one end of ,said bore including a member mounted in said body,.a pump plunger working in said bore, a combined suction and release valve mounted in said member, said valve including a part arranged to be contacted by 50 one end of the pump plunger on its discharge stroke to effect release of fuel from said chamber;

and a pump delivery valve, said member having passages formed therein for placing the pump chamber in communication with the outlet side of said suction and release valve and with the inlet side of said delivery valve and for placing the inlet side of said suction and release valve in communication with the liquid supply for the pump. v

from the pump chamber, and a pumpdelivery valve, said member having passages formed therein for placing the pump chamber in com-.

munication with the outlet side of the suction valve and with the inlet sidesof the delivery 6 valve and of the release valve and for placing the inlet side of-the suction valve and the outlet side of the release valve in communication with the liquid supply for the pump.

4. In a reciprocating pump, a pump body, a 10 cylinder mounted in said body providing a working bore, a member mounted in said body in alignment with said cylinder at-one end thereof and cooperating therewith to form a pump chamber, a pump plunger working in said bore, 15

valve means mounted in said member for admitting liquid to said chamber and for releasing liquid therefrom including a part arranged to be contacted byone end of the plunger on its discharge stroke to eflect release of liquid from said chamber, and a pump delivery valve, said member having passages formed therein for placing v said valve means in communication with the pump chamber and with the liquid supply for the pump and .for placing the pump chamber in communication with the pump delivery valve.

5. In a reciprocating pump, a pump body, a cylinder mounted'in said body providing a working bore, an annular member mounted in saidbody in alignment with saidcylinder at one end there- 30 of and cooperating therewith to provide a pump chamber, suction and releasevalve means mounted insaid member including a part extendin centrally therethrough 'to be contacted by one end of the pump plunger,on its discharge stroke' for effecting release of liquid from the pump chamber, a pump delivery valve, passages extending longitudinally. through said member for flow of liquid'from said valve means to the pump chamber of: the suction stroke of the pump and 40 for flow of liquid from the pump chamber to the delivery valve on the working stroke of the pump, and transverse passages extending laterally through the wall of said member between the longitudinally extending passages for flow of liq.- uid from the liquid supply to the inlet side of said valve means and for return flow of excess liquid from the pump chamber to said supply.

6. In a reciprocating pump having a working bore, a pump body, means providing a pump chamber at one end of said bore including a member mounted in. said body, a compound pump plunger working in said bore, valve means mounted in said member for admitting liquid to said chamber and for releasing liquid therefrom ineluding a part arranged to be contacted by one end of the plunger on its discharge stroke to effect release of liquid from said chamber, a pump delivery valve, said member having passages formed therein for placing said valve means in communication with the pump chamber and with EDVIN OSSIAN PARCIVAL Tarzan-

Images