GB2191251A

GB2191251A - Fuel injection pumps

Info

Publication number: GB2191251A
Application number: GB08712572A
Authority: GB
Inventors: Raymond Edward Abinett
Original assignee: Lucas Industries Ltd
Current assignee: ZF International UK Ltd
Priority date: 1986-06-03
Filing date: 1987-05-28
Publication date: 1987-12-09
Also published as: ES2005608A6; IT1205048B; GB2191251B; US4711618A; IT8720735A0; FR2599430A1; FR2599430B1; GB8712572D0; JP2581921B2; DE3718499C2; JPS6316165A; DE3718499A1; GB8613409D0

Description

G132 191 251A 1 SPECIFICATION be undesirably long since because of the

axial movement of the distributor member it would Fuel injection pumps have to have a length greater than the spacing between the aforesaid planes by at least the This invention relates to rotary distributor fuel 70 allowed axial movement of the distributor injection pumps of the kind comprising a ro- member. The formation of such a groove tary distributor member which is mounted would result in a substantial reduction in the within a cylindrical bore defined in a fixed bearing surface of the distributor member and body part, the distributor member defining a in addition, the loss would be concentrated in plunger bore in which is mounted a reciproca- 75 one area of the distributor member.

ble plunger, the plunger during inward move- The object of the present invention is to ment under the action of cam means displac- provide an injection pump of the kind speci ing fuel from said plunger bore, a passage in fied in a simple and convenient form.

the distributor member which receives fuel According to the invention a rotary distribu from the bore during the inward movement of 80 tor fuel injection pump of the-kind specified the plunger, a plurality of angularly spaced comprises first and second balancing grooves outlet ports formed in the body and opening formed on the periphery of the distributor onto the surface of the cylindrical bore, a de- member for communication with the inlet livery groove on the periphery of the distribu- ports and outlet ports respectively, a passage tor member, said delivery groove registering 85 extending within the distributor member and with said outlet ports in turn during succes- interconnecting the balancing grooves, said sive inward movements of the plunger, a plu- balancing grooves effecting communication as rality of angularly spaced inlet ports formed in the distributor member rotates, between each the body and opening onto the surface of the outlet port and an inlet port to stabilise the cylindrical bore, the inlet ports and outlet 90 fuel pressure in the outlet ports.

ports being disposed in axially spaced planes An example of an injection pump in accor respectively, said inlet ports communicating dance with the invention will now be de with a source of fuel under pressure, at least scribed with reference to the accompanying one inlet groove on the periphery of the distri- drawings in which:

butor member and positioned to register in 95 Figure 1 is sectional side elevation showing turn with said inlet ports to allow fuel to flow a portion of the pump, and into said plunger bore during the time the Figure 2 is diagrammatic view to an en plunger is allowed to move outwardly by said larged scale showing the disposition of various cam means, and stop means for limiting the ports and grooves in the pump.

outward movement of the plunger, said stop 100 Referring to Figure 1 of the drawings the means being constructed so that the extent of pump comprises a multi-part body 10 in outward movement of the plunger depends which is mounted a sleeve 11 which defines a upon the axial position of the distributor mem- cylindrical bore 12 which accommodates an ber within the cylindrical bore. axially movable rotary distributor member 13.

The axial spacing of the inlet ports and the 105 The distributor member projects from the bore delivery ports is necessary when the pump is 12 and has an enlarged portion 14 in which is required to deliver fuel at a very high pressure formed a diametrically disposed plunger bore to a so-called direct injection compression ig- 15 which mounts a pair of pumping plungers nition engine. It is known in the art to stabil- 16. The plungers at their outer ends are en- ise the pressure in the outlet ports following 110 gaged by cam followers each of which in delivery of fuel therethrough, in order to cludes a shoe 17 and a roller 18. The shoes achieve regularity of fuel delivery. Where the and rollers are confined between a pair of delivery ports and the inlet ports lie in the plates 19 secured to the enlarged portion 14 same plane this is achieved using a single ba- of the distributor member and the rollers can lancing groove which is so disposed on the 115 engage with cam lobes formed on the internal surface of the distributor member and which peripheral surface of a cam ring 20 which is has a width sufficient to achieve communi- angularly adjustable within the body of the cation between an outlet port which has re- pump in known manner, to achieve variation ceived fuel and the inlet port which precedes in the timing of fuel delivery.

the outlet port in the direction of rotation of 120 The distributor member is driven by means the distributor member. In such a pump the of a drive shaft which is supported in the roles of the inlet groove and delivery groove body and which has an annular head 21 which are combined and the balancing groove can be surrounds the enlarged portion 14 of the dis positioned on the distributor member so as to tributor member. The head is provided with a ensure that at some time between successive 125 pair of axially extending radial slots 22 in fuel deliveries to each outlet port, that outlet which are located the drive plates 19 and the port is placed in communication with an inlet cam followers and in addition, the internal sur port. face of the head 21 is tapered to provide a Where the inlet ports and grooves are axi- stop surface 23 and for co- operation with the ally spaced, a single balancing groove would 130stop surface 23, each shoe 17 is provided on 2 G132 191251A 2 its opposite sides, with stop surfaces 24 depends upon the axial position of the distri which are shown in dotted outline. butor member and it will be understood that The distributor member is biased by means as the distributor member is moved towards of a coiled compression spring 25 interposed the right as shown in Figure 1, further out between the distributor member and the en- 70 ward movement of the plungers will be al larged portion of the drive shaft and move- lowed so that an increased quantity of fuel ment of the distributor member against the will be supplied through each outlet.

action of this spring is achieved by admitting In order to stabilise the fuel pressure in fuel under pressure to a chamber 26 at the each outlet port following delivery of fuel and opposite end of the distributor member, the 75 before the next delivery of fuel to that port, a control of the pressure in the chamber being pair of balancing grooves 34, 35 are formed conveniently effected by an electrically con- in the periphery of the distributor member as trolled valve. seen in Figure 2 and are interconnected by a Formed in the sleeve 11 is a series of inlet passage 37 conveniently formed in two parts.

ports 27 which communicate with a circumfer- 80 The grooves 34 and 35 are axially spaced by ential groove 28 formed on the periphery of an amount equal to the separation of the the sleeve and which extend inwardly to open aforesaid planes so that the groove 34 can onto the cylindrical surface of the bore 12. communicate only with the outlet ports 29 The groove 28 communicates with a source while the groove 35 can communicate only of fuel under pressure conveniently a low 85 with the inlet ports 27. The arrangement is pressure pump which is driven by the drive such therefore that as the distributor member shaft. The ports 27 are equiangularly spaced rotates each outlet port between successive and as will be seen from Figure 2, four inlet deliveries of fuel thereto, will be connected to ports are provided. Also formed in the sleeve an inlet port so as to permit the pressure in are four outlet ports 29 which are connected 90 the outlet port to stabilise before it next re to outlets 30 respectively formed in the body ceives fuel. The lengths of the grooves 34, and connected in use to the injection nozzles 35 are substantially equal to those of the respectively of the associated engine. Each grooves 32, 33 being such as to take into outlet can incorporate a delivery valve. The account the allowed axial movement of the outlet ports 29 are also equiangularly spaced 95 distributor member. The widths of the and are located in a plane normal to the axis grooves 34, 35 are comparable to the widths of rotation of the distributor member, which is of the grooves 32, 33 and although the axially spaced from a similar plane containing grooves 34 and 35 are not diametrically dis the inlet ports 27. From Figure 2 it will be posed, so that full balance of the forces act seen that the inlet and outlet ports are alter- 100 ing on the distributor member is not obtained, nateiy spaced about the axis of rotation of the the improvement is significant as compared distributor member. 1 with the use of a single groove described in The plunger bore 15 communicates with an the opening of the present specification.

axi ' al passage 31 formed in the distributor

Claims

member. This passage communicates with a 105 CLAIMS longitudinal inlet

groove 32 and a longitudinal 1. A rotary distributor fuel injection pump outlet groove 33, the two grooves being axi- comprising a rotary distributor member which ally spaced in the same manner as the inlet is mounted within a cylindrical bore defined in and outlet ports. It will of course be under- a fixed body part, the distributor member de stood that Figure 2 is diagrammatic and the 110 fining a plunger bore in which is'mounted a groove 32 can register only with the inlet reciprocable plunger, the plunger during inward ports 27 and the groove 33 only with the movement under the action of cam means dis outlet ports 29. As the distributor member placing fuel from said plunger bore, a passage rotates therefore the groove 33 will move into in the distributor member which receives fuel register with an outlet port 29 just before in- 115 from the bore during the inward movement of ward movement of the pumping plungers 16 the plunger, a plurality of angularly spaced can take place and during the inward move- outlet ports formed in the body and opening ment of the plungers fuel will be displaced to onto the surface of the cylindrical bore, a de an outlet. As the distributor member further livery groove on the periphery of the distribu rotates the groove 33 will move out of regis- 120 tor member, said delivery groove registering ter with an outlet 29 and the groove 32 will with said outlet ports in turn during succes move into register with an inlet port 27 to sive inward movements of the plunger, a plu permit the plungers to be moved outwardly by rality of angularly spaced inlet ports formed in the action of fuel under pressure. The outward the body and opening onto the surface of the movement of the plungers causes similar 125 cylindrical bore, the inlet ports and outlet movement of the followers and the outward ports being disposed in axially spaced planes movement of the plungers and followers will respectively, said inlet ports communicating be arrested when the stop surfaces 24 on the with a source of fuel under pressure, at least shoes engage with the stop surface 23. The one inlet groove on the periphery of the distri extent of outward movement of the plungers 130 butor member and positioned to register in 3 GB 2 191251 A 3 turn with said inlet ports to allow fuel to flow into said plunger bore during the time the plunger is allowed to move outwardly by said cam means, stop means for limiting the out- ward movement of the plunger, said stop means being constructed so that the extent of outward movement of the plunger depends upon the axial position of the distributor member within the cylindrical bore, first and sec- ond balancing grooves formed on the periphery of the distributor member for communicatien with the inlet ports and outlet ports respectively, a passage extending within the distributor member and interconnecting the ba- lancing grooves, said balancing grooves effecting communication as the distributor member rotates, between each outlet port and an inlet port to stabilise the fuel pressure in the outlet ports.
2. A rotary distributor fuel injection pump comprising the combination and arrangement of parts substantially as hereinbefore described with reference to the accompanying drawings.

Printed for Her Majesty's Stationery Office by Burgess & Son (Abingdon) Ltd, Dd 8991685, 1987. Published at The Patent Office, 25 Southampton Buildings, London, WC2A lAY, from which copies may be obtained-