US2274315A - Fuel injection system or device for internal-combustion engines - Google Patents

Description

Feb. 24, 1942. G. AMERY 2,274,315

FUEL INJECTION SYSTEM OR DEVICE FOR INTERNAL-COMBUSTION ENGINES Filed Nov. 24, 1939 5 i2 1. 57 E; 26' I 5 55 28 I r 58 I Z9 59 ig fi 36 r 51 31 ZZ 2? 21 25 F 415. j .55 1 j7-\ 5.9 1 H a I 6% 1.9 4; Z8 F 57 17 56 .57

y 7 6'6 59 27 2.9 5 AN 2] 6759 6% 50 51 -J7 a; A I 16 gzgfim Patented Feb. 24, 1 94:2

FUEL INJECTION SYSTEM OR. DEVICE FOR INTERNAL-COLIBUSTION ENGINES George Amery, ol bury, England Application November 24, 1939, SerialNo. 305,971 In Great Britain November 24, 1938 6 Claims. (chess-1cm) This invention comprises improvements in or relating to fuel injection systems or devices for internal-combustion engines.

vIt is an object of the invention to provide an alternative form of fuel-injector to that described In the aforesaid United States patent there is described an injection system in which a fuelinjector is provided with a needle-valve to control the flow of fuel through the nozzle and the needle-valve is opened by fuel pressure acting upon an opening-piston, which fuel pressure is continuously maintained and is closed by the application of fluid pressure, at the desired time of closing, to a closing-piston capable of overcoming the action of the opening-piston. In this construction the opening-piston and the passage to the fuel-jet opening are subject to the same fluid pressure. The inverse arrangement has also been proposed, namely to maintain the pressure in United States Patents No. 2,150,574 and No.

on .the closing-piston continuously and to vary a the pressure periodically on the opening-piston, which was to have an eilective area larger than the closing-piston.

According to the present invention, in a fuel injection system in which a fuel-injector is provided having a fuel-jet opening and valve therefor controlled by an opening-piston and a closins-piston and wherein pressure on the openingpiston is varied periodically to determine the opening and closing of the valve, there is provided an opening-spring to assist the opening action of the opening-piston. v

The opening-piston may be of an effective area equal to, or smaller than, that of the closingpiston. Closing pressure may be applied by the continuous supply of fuel to the closing-piston and the closing-piston may be in communication this when the needle-valve is opened fuel can with a passage leading to thevalve seating of the fuel-jet opening. The opening-piston is not then in direct communication with the passage leading to'the valve seating and the fuel-jet opening.

As in the case of the said prior patent the valve is shut by the fuel pressure while pressure is still fully maintained at the valve seating.

The invention further comprises in a fuel injection system in which an injector is provided having a fuel-jet opening and a valve therefor provided with, an opening-piston and a connection from a distributor thereto so that the valve is opened by the periodic application of pressure under the control of. the distributor to the opening-piston, the provision or an auxiliary cut-oil? valve in a fuel passagel leading "tothe fuel-jet,

cylinder.

which cut-off valve is subject to the action of said pressure from the distributor so that the shuttle. valve opens the said passage when the, distributor applies pressure to the opening-piston and closes it when the distributor pressure is'released or diminished from said piston. Thus pressure is cut ofi from the valve seating and jet opening immediately after the valve is closed and is not reapplied until the application of pressure to the opening-piston moves the cut-off valve over when the valve at the jet opening is to be opened again, and any undesired leakage of the fuel into the engine cylinder at periods when the injection is supposed to be cut off is thus prevented.

The following is a description, by Way of example, of constructions in accordance with the invention, reference being made panying drawing in which-' Figure 1 is a longitudinal section through an injector nothaving an auxiliary cut-off valve, and

Figure 2 is a similar view of another injector working on the same principle as Figure 1 but provided with an auxiliary cut-01f valve.

Referring to Figure 1 the fuel injector comprises a body portion ll having a central axial bore l2. To the body I I there is secured by a union nut l3 a nozzle M having in the tip fueljet openings l5 and a seating l6 behind the inner ends of said openings 15 on which seating a needle-valve H is adapted to close. The needleto the accomvalve I! fits closely within the nozzle l4 and is provided with grooves l8 to diminish leakage. Around the end of the needle-valve'between the cylindrical portion which fits the bore in the nozzle and the seating I 6 there is an enlargement I 9 of the internal bore of the nozzle H which constitutes a pressure chamber, and from flow through the jet openings 15 into the engine Within the body II is a reaction-nut 20 seated against whichis a spring 2| and the spring 2| bears on a shouldered pressure member 22 which in turn bears through a ball 23 on the stem 24 of the needle-valve, I1. Thus the spring tends to keep the needle-valve closed. 7

Secured on the body H by means of a union nut 25 is a control section Ziwhich contains a control chamber 21. The control chamber 21 has a cylindrical bore, coaxial with the other parts of the injection nozzle, inwhlch works a control piston 28. The piston 28 has a piston rod 28 (sealing the chamber 21) which passes spring 2|.

riods when injection is the rod 30 on the back of the shouldered pressure member 22. The parts 28, 29 and 30 may be separate parts, if desired, to avoid difliculties due to the problem of securing exact concentricity of all the various bores. Between the control extension 26 and the reaction member 20 there is inserted a spring washer 3| to prevent the reaction member from unscrewing under vibration, while permitting it to remain in any desired position of adjustment, so that the effective pressure of the spring 2| can be varied. I

Coaxial with the end of the control extension 26 is a nipple 32 for connection to a supply pipe for fuel under injection pressure. It will be observed that this pressure acts on the piston 28 in a direction to close the needle-valve |1 through the intermediary of the piston rods 28 and 30 and the pressure member 22. By means of passages 33, 34 and 35 drilled respectively in the control section 26, the injector body II and the nozzle ll the fuel oil is conveyed to the pressure chamber l8 behind the needle-valve seating l6.

Within the control chamber 21 there is a strong spring 36 which acts upon the piston 28 in a direction to oppose and partly balance the closing pressure of the injection fuel. In the side of the control extension 26 there is a passage 31 which is connected by a connector 38 to a distributor pipe. It will be observed that the connector 38 surrounds the cylindrical exterior of the control extension 26 closely and has ascrewed boss 39 on one side seated in which is a double-cone nipple 40, so that a suitable screwed end on the distributor pipe can be easily coupled up to it in a pressure-tight manner. The passage. 31 leads into the control chamber 21.

The face of the piston 28 which abuts upon the spring 36 constitutes an openingpiston which is,-

however, of smaller effective area than the other face, which constitutes a closing-piston. However, by the aid of the spring 35, should pressure be applied by the distributor through the passage 31 to the opening-piston this will be sufliclent to cause the needle-valve H to open, the injection pressure acting on the needle-valve |1 being sufflcient to overcome the resistance offered by the The needle-valve |1 itself has a certain area, as will be seen from the drawing, which acts as an assistance to the opening-piston in opening the needle-valve but the combined effective areas taken together do not reach the area of the closing face of the piston 28, and the spring 35 therefore fulfils an essential function in ensuring the opening of the needle-valve against the continuous pressure of the fuel in the closing direction.

No closing spring is. provided acting on the piston 28 as the fuel under pressure acting continuously on the piston 28 in the closing direction tends at all times to press the piston towards the needle-valve l1.

An outlet. for seepage is provided at 4| and this may be provided with a nipple and a connection to a drain pipe if desired.

' The distributor and the fuel supply connec-. tions may be operated as described .in my prior United States Patent No. 2,150,574 with the exception that the valves and operating mechanism of the distributor are modified so that pressure is applied through the passage 31 from the distributor whenever the injection is to take place instead of applying pressure during the peto be prevented. It will therefore be appreciated that (provided the proper fuel pressure is available) whenever injection is to take place the needle-valve H is caused to open by the application of pressure through the passage 31 and when injection is to terminate this pressure is released or diminished, thus permitting the needle-valve H to be closed under the influence of the fuel pressure applied through the nipple 32 and of the spring 2|. In all other respects the control may be as described in my aforesaid United States patent and in United States specification Serial No. 225,025 and the present invention therefore provides an alternative form of injector to that described in the said prior specification.

In the injector asillustrated in Figure 1 of the drawing the fuel pressure is maintained continuously in the pressure chamber Hi and the seating i6 is therefore the sole means of preventing leakage of the fuel into the engine cylinder at other times than that at which injection is to take place, but in my aforesaid United States Patent No. 2,150,574 I have described an auxiliary cut-off valve which is'operated by the distributor pressure so as to prevent the pressure at the needle-valve seating from being applied nut 20 as already described. Moreover, the nozzle body 50 is provided with a fuel passage 34 communicating with a passage 35 in the nozzle also as already described.

. In the construction illustrated in Figure 2 the injector body 50 is enlarged eccentrically at the head end as indicated in the figure at 5| and the control section of the injector instead of being held on the end of it like the section 26 of Figure l is constituted. by a cylindrical control section 52 which is enclosed within the enlargement 5| and held there by a screwed plug 53 on which a nipple 54 is formed for connection to the source of fuel under pressure.

The control section 52 contains a control chamber 21 as already described and a piston 28 which is acted upon by an opening spring 36. There is,

55 moreover, a lateral connection 38 for a nipple of moved against this pressure by means of a return spring 51. Instead of the spring 51 there might be provided a connection from passage so that the valve is returned by fuel-pressure. The auxiliary cut-oil valve has a circumferential groove 58 about the middle of its length which is arranged, when the pressure in the chamber 21 forces the valve back against the spring 51, to be brought into register with a fuel passage 53 which isdrilled in the control section 52 and serves to connect the high pressure supply through the plug 53 with the fuel passages 34 and 35 before referred to. Thus when the distributor applies pressure through'the connection 9 to cause the needle-valve to open the auxiliary cut-off valve is forced back and permits fuel pressure from nipple 54 to reach the seating of the needle-valve I'I. At other times the spring 51 presses the valve 56 toward the control chamber 21 and shuts off the pressure from the lower part of the passage 59. L. the same time a flat 60 in the underside of the valve 56 serves to connect the passage 59 below the valve 56 with a drain passage 6| in the control section 52, which drain passage leads to the central space around the piston rod 29. It will be appreciated that the pistonrod 29 passes through the reaction nut 20 with 'a clearance so that the seepage past the needle-valve I! can also find its way past the piston rod 29 into the-same space as that to which the seepage passage 6| delivers any fuel from the shuttle valve 56. It is necessary to provide for this seepage being carried away from the nozzle and this is done in the following manner: v I

A packing washer 62 is provided between the control extension 52 and the bottom of the recess in the body 50 within which the extension 52 is located. Against this packing washer the extension 52 is forced by means of the screwed plug 53 before referred to. The packing washer is, however, slightly smaller in diameter than the flat face on which it rests, so that an annular fuel passage is provided around it. A radial channel 63 in the body 58 below the packing washer 62 connects the central space around the piston rod 29 with the annular passage and a channel 64 in the periphery of the extension 52 connects the annular passage around the packing washer' 62 with the bore of the shuttle valve beyond the passage 59. A further channel 65 in one side of the bore of the shuttle valve ensures communication with the space in which the spring 51 is located and from here there is a seepage passage 56 which may, if desired, be connected by a suitable nipple to'a drainage pipe. If the valve56 is returned by fuel pressure instead of by spring 51 the drain must be located elsewhere for example as outlet 4! in Figure 1.

In order to prevent the valve 56 from rotating in the construction illustrated, so that the flat 60 ceases to register with the passages 58 and SI, it has a stem 61 which is provided with a flat on one side and a grub screw, not shown in the drawing, bears on this flat and thus prevents its rotation. v

In the operation of this device it will be seen that the application of pressure in the pressure chamber 21 will serve not only to open the needle-valve H but also to push open the shuttle valve 56, thus admitting pressure to the pressure chamber l9. As 'soon as this pressure is cut off that which is required to sustain the needle-valve I! open.

When the valves are opened, owing to the lightness of the shuttle valve and to the fact that it has a large pressure face compared with its weight and the strength of its spring, it will openeven more rapidly than the needle-valve I! so that there will be no lag between the opening of the needlevalve and the commencement of spraying- This is further assisted by the factnozzle I4 or the necessity of taking apart the intermediate elements. Furthermore the quantity of fuel necessary to operate the parts through the distributor connection 38 is very small and thus a minute quantity of fluid entering from the distributor connection will cause the needlevalve to open and the release of this minute quantity will cause it to shut, thus ensuring prompt operation and avoiding wide fluctuations of fluid in the pressure pipe lines and parts connected thereto.

Although in the system as hereinabove described the openingand closing-pistons are actuated by fuel under injection pressure it is to be understood that these pistons might be operated in accordance with the invention by the shuttle valve 56 is pushed over and connects the pressure chamber IE to the leakage outlet so ,that fuel pressure is prevented from acting on "the seating of the needle-valve l1 except at such .,move over to alter the connection until the presinthewontrol chamber 2'! has fallen below another fluid than the fuel, operating if desired under another pressure, and in this case the size of the pistons and/or the strength of the spring will be modified so as to secure the necessary force for operating thev parts In another alternative construction instead of connecting the passage 33 to the space behind the closing piston face of the piston 28 (Figure 1) may be connected to the control chamber 21. In this case if the passage opens into the wall just above the opening piston face of piston 28 when the valve I! is closed, the piston 28 will cut off the fuel from the passage 34 and act as a kind of auxiliary cut-01f valve.

I claim:

LA fuel-injector comprising in combination an injector-body, a fuel-jet opening therein, a

valve chamber, a valve for closing said fuel-jet opening, a spring for holding said valve on its seating, a piston face upon said valve for opening same against said spring under fuel pressure in said valve chamber, a cylindrical chamber providing a control cylinder in said body in line with said'valve, a piston in said control cylinder, a compression member extending in sealed relation with said cylindrical chamber from said piston into engagement with said valve, means for admitting fuel under pressure to the piston face on said piston which is remote from said valve and to said valve-seating, a spring hearing on the other piston face of said piston to assist the movement of the piston away from said valve. and means for admitting fluid under pressure to said other piston face.

2. A fuel-injector as claimed in claim 1, wherein the control cylinder is located in a separate control section of the injector-body detachably secured thereto.

" said opening, a cylindrical chamber providing a control cylinder in said body in line with said valve, a control piston in said cylinder, means connecting the control piston with said valve, a fuel passage leading to the valve seatingand fuel-jet opening, an auxiliary cut-off valve in said passage, which valve is provided with a piston face in communication with the portion of said control cylinder which is nearer the valve, so that pressure in said portion control cylinder serves to move the auxiliary cut-off valve to open said fuel passage at the same time that the control piston is operated to move away from the first said valve, and means to return said auxiliary cut-off valve when pressure in said portion of control cylinder is diminished to close saidv fuel passage.

4. A fuel-injector for a system asclaimed in claim 3, wherein the auxiliary cut-01f valve is located within a control section containing the control piston, and wherein the control section is detachably secured to the body of the injector.

5. A fuel-injector as claimed in claim 3, wherein the auxiliary cut-ofi valve is removable from the injector-body through a removable nipple in the wall thereof.

6. In a fuel injection system the combination of a fuel-injector body, a fuel-jet opening therein, a valve for said fuel-jet opening, a cylindrical control-chamber, a piston in said control chamber, means operatively connecting said piston to said valve, an opening spring operatively connected to said piston to assist opening of the valve and means to supply fuel under pressure to said control chamber on the face of said piston such as to close said valve against the spring said fuel supply means having also a conduit open to the seating of said valve, and separate means to supply fuel under pressure to the other face of said p ston to assist in opening the valve.

GEORGE AIVIERY.

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