GB2170558A - Liquid fuel injection pump - Google Patents

Abstract

A liquid fuel injection pump includes a housing 10 having a fuel outlet 19 and a fuel inlet 24. A reciprocable plunger 21 is angularly adjustable to determine the quantity of fuel pumped by an adjustable means including a lever 31. A pin is engageable with the lever 31 to fix the plunger at a predetermined angular position. The pin is provided with a tail portion 37 which prevents a fuel pipe being connected to the outlet or the inlet while the pin is engaged with the lever. The pin may engage in a slot formed in the upper surface of the lever. <IMAGE>

Description

SPECIFICATION Liquid fuel injection pump This invention relates to a liquid fuel injection pump for supplying fuel to a combustion space of an internal combustion engine, the pump comprising a housing defining a bore, a plunger reciprocable within the bore, an outlet from the bore and adjustable means carried by the housing whereby the angular setting of the plunger within the bore can be adjusted to enable the quantity of fuel delivered through said outlet to be varied, the pump including a fuel inlet connection through which fuel can be supplied to said bore.

The pump as described above is supplied to an engine manufacturer with the plunger and adjusting means set in a predetermined angular position for example the maximum fuel position, and all the engine manufacturer has to do is to mount the pump on the engine, connect governor linkage to the adjusting means, the governor linkage also having been preset in a predetermined position, clamp the pump to the engine and then release whatever has been used to set the predetermined position of the plunger and the governor linkage. The engine can then be started and the pump will supply fuel to the engine under the control of the governor.

It is known to use a pin which is in screw thread engagement with the housing to hold the plunger ana adjusting means in the aforesaid predetermined position ana once the governor linkage has been connected and the pump clamped it is necessary to unscrew the pin at least until it is in a position so that it will no longer interfere with the angular movement of the plunger. If the step of freeing the plunger is omitted and an attempt made to start the engine, damage can result to the engine if it starts, since it will be supplied with the maximum quantity of fuel and the governor will be inoperative to reduce the amount of fuel.

The Qbject of the invention is to provide a pump of the kind specified in a simple and convenient form.

According to the invention a pump of the kind specified includes a pin extending to the exterior of the housing, said pin when in an operative position serving to retain said adjustable means at a predetermined position corresponding to a predetermined angular position of the plunger, said pin having a tail portion which in the operative position of the pin prevents the connection to the inlet or outlet of the pump of a fuel conveying pipe, the pin being movable to an inoperative position to release said adjustable means and to allow the connection of said fuel conveying pipe.

In the accompanying drawings: Figure 1 is a sectional side elevation of a pump in accordance with the invention, Figure 2 is a plan view of the pump seen in Figure 1, and Figure 3 is a view similar to Figure 1 showing a modification.

With reference to Figures 1 and 2 the pump comprises a housing 10 having a flange portion 11 in which is formed a pair of apertures 12 for the reception of screws whereby the housing can be secured to an engine. Extending through the housing is a stepped bore 13 against a step in which is located a flanged pump barrel 14. The barrel is held in position against the step by a hollow cylindrical delivery valve body 15 which in turn is engaged by a hollow outlet housing 16 which is in screw thread engagement with the housing 10.

Slidable within the body 15 is a delivery valve member 1 7 of conventional form and which is biased into engagement with a seating by means of a coiled compression spring 18 housed within a chamber defined in the outlet housing 16 and communicating with an outlet 19. The portion of the housing 16 which defines the outlet is screw-threaded whereby a pipe can be secured thereto, the pipe in use leading to a fuel injection nozzle of the engine.

The pump barrel defines a bore 20 in which is mounted a reciprocable pumping plunger 21 and formed in the wall of the bore is a pair of fuel inlet ports 22 which communicate with a fuel supply gallery 23 which is defined in the housing 10 and surrounds the barrel. The gallery communicates with a fuel inlet 24 opening onto an inclined surface 25 on the exterior of the housing.

The plunger 21 is provided with the conventional form of fuel control helix (not shown) which communicates with one of the ports 22 in order to terminate the delivery of fuel, at some point during the inward movement of the plunger. In order to vary the quantity of fuel delivered by the pump the plunger is movable angularly and this is effected by an adjustable means which includes a sleeve 26 mounted about the barrel and having a slotted portion extending beyond the barrel. The plunger has a pair of dogs 27 engaged in the slots respectively of the sleeve whereby angular movement of the sleeve will effect angular adjustment of the plunger while at the same time allowing the plunger to move axially. The plunger- projects beyond the slotted end of the sleeve and defines a foot which is engaged by a spring abutment 28.Interposed between the abutment 28 and a further abutment 29 is a coiled compression spring 30 the duty of which is to bias the plunger outwardly after it has been moved inwardly by an engine driven cam not shown.

The abutment 29 bears against a step defined by a counter bore in the housing. Moreover, it locates against a lever 3 1 which is secured to the sleeve 26. The abutment 29 is preferably retained in position by a suitable peg not shown so that the lever and- sleeve 26 are also retained against axial movement.

The lever is provided with a depending pin 32 which in use, is connected to a governor link age extending from a governor which is mounted on the engine.

In operation, when the plunger 21 is moved inwardly fuel will be expelled from the portion of the bore lying between the plunger and the delivery valve, through the ports 22 and this fiow of fuel will continue until the plunger covers these ports. When this takes place the fuel inthe bore is pressurised and acts-to lift the delivery valve member 17 so that fuel is supplied to the injection nozzle associated with the pump. The delivery of fuel ceases when the aforesaid helix uncovers one of the ports 22 whereupon the delivery valve closes and the delivery of fuel ceases. The remaining quantity of fuel in the bore flows through the uncovered port 22 into the fuel supply gallery.

The axial position of the plunger at which the helix uncovers the aforesaid port depends upon the angular setting of the plunger and this can of course be adjusted by moving the lever 31 angularly about the axis of the plun ger. When the plunger is permitted to move outwardly, the spring effects such movement and a fresh quantity of fuel is drawn into the bore as soon as the prunger uncovers the ports 22.

When the pump is assembled to the engine it is convenient that the plunger be set in a predetermined angular position and that the governor linkage should also be set in a pre determined angular position. This enables the housing of the pump to be located in a bore in the engine, the linkage to be connected to the pin 32 and finally the clamping nuts or bolts of the housing of the pump secured.

The engine manufacturer is therefore relieved of the task of adjusting the setting of the plunger in relation to the governor.

Returning to Figure 1 the housing 10 is pro vided with a drilling 33 which extends parallel to the axis of the plunger but is to one side of a plane normal to said surface and passing through the inlet. Located within the drilling is a pin 34 the lower end of which can engage in a slot formed in the upper surface of the lever 31 and when this engagement is effected, the lever 31 is prevented from moving angularly so that the plunger also is prevented from angular movement. In the assembly of the pump the pin is engaged in the slot and the pump barrel is rotated by an eccentric adjustment device 35 so that the pump delivers a predetermined quantity of fuel which may be the maximum quantity of fuel. Once this adjustment has been effected the barrel is clamped. The pump can then be said to have been calibrated and it is ready for supply to the engine manufacturer.As previously explained it is essential to ensure that the pin is removed from the slot in the lever 31 before an attempt is made to start the engine. The pin is axially movaole in the drilling 33 but is restrained against such axial movement by the provision of a resilient insert 36 located in the housing and through which the pin extends, the insert imparting sufficient friction to prevent movement of the pin during transport. In the example of Figure 1 the pin is provided with a tail 37 which, in the inoperative position of the pints shown, overlies the inlet 24 thus preventing the connection to the pump of a fuel supply pipe. The action of moving the pin angularly in the clockwise direction as seen in Figure 2, will cause the tail of the pin to climb up the inclined surface 25 to rest on the end surface 38 of the housing.Such movement, will cause the pin to move axially within the drilling, to its inoperative position. Thus the practical effect is that a fuel supply pipe cannot be connected to the inlet 24 unless the pin is in its inoperative position or even removed completely from the drilling. There is no harm in allowing the tail 37 of the pin two remain in contact with the surface 38. However, with the configuration shown in Figure 1 there is a slight danger that the pin will- be moved in the anticlockwise direction and leave the surface making it possible for the pin to move axially in the drilling towards its operative position. This can be prevented by providing another tail portion to the pin which will interfere with the outlet housing 16 if an attempt is made to move the pin in the anticlockwise direction.

Figure 3 illustrates an alternative arrangement in which the pin 39 has a tail 40 which extends at right angles to the main portion of the pin so that-in the operative position of the pin the tail 40 prevents the connection of a fuel line to- the outlet 19. In this example the pin is biased by a spring 41 which is contained within an enlargement 42 of the-drilling which contains the pin. The spring at one end engages a hollow abutment 43 in the enlargement 42 and at its other end it engages against an abutment secured to the pin 39.

The pin 39 also carries an eccentric washer 44 which in the operative position of the pin lies within a complementarily shaped portion 45 of the enlargement of the-drilling. When the pin is moved outwardly against the action of its spring, and rotated through 180"the washer 44 lies on the surface 36 of the housing to maintain the pin in its inoperative position. With the pin in this position it is possible to connect a pipe to the outlet 19.

It will be understood thåt the spring41 can be used in the arrangement shown in Figure 1.

By the arrangements described the pump is unable to deliver fuel to the associated engine whilst the pin is in the operative position.

The pin as described can be applied to a pump in which the adjusting means takes the form of a toothed segment which is secured to or forms part of the sleeve 26 and which is engaged by a rack bar slidable in the housing. In this case the pin is engaged within a drilling in the rack bar to secure the rack bar, the sleeve and the plunger in a predetermined position.

Claims (13)

1. A liquid fuel injection pump for supplying fuel to a combustion space of an internal combustion engine, the pump comprising a housing defining a bore, a plunger reciprocable within the bore, an outlet from the bore and adjustable means carried by the housing whereby the angular setting of the plunger within the bore can be adjusted to enable the quantity. of fuel delivered through said outlet to be varied, the pump including a fuel inlet connection through which fuel can be supplied to said bore, and a pin extending to the exterior of the housing, the pin when in an operative position serving to retain said adjustable means at a predetermined position corresponding to a predetermined angular position of the plunger, characterised in that said pin has a tail portion which in the operative position of the pin prevents the connection to the outlet or to a fuel inlet of the pump, of a fuel conveying pipe, the pin being niovable to an inoperative position to release -said adjustable means and to allow the connection of said fuel conveying pipe.

2. A pump according to Claim 1 in which said pin is displaceable axially from its operative position to its inoperative position.

3. A pump according to Claim 2 including means for resisting movement of the. pin axially from its operative to its inoperative position.

4. A pump according to Claim 3 in which said means comprises an insert formed from resilient material and through which the pin extends, the insert being located in the housing.

5. A pump according to Claim 3 in which said means comprises a coiled spring one end of which engages an abutment in the housing and the other end of which engages an abutment secured to the pin.

6. A pump according to Claim 4 or Claim 5 in which said pin is located in a drilling extending substantially parallel to the axis of movement of the plunger, the end of the pin remote from said tail engaging with a part of said adjustable means.

7. A pump according to Claim 6 in which said tail is formed at an acute angle relative to the remaining portion of the pin, the tail in its operative position overlying a surface of the housing in which said inlet is formed and in the operative position preventing connection of the fuel conveying pipe to said inlet, said tail when it is displaced in a lateral direction to permit connection of said pipe, engaging with said surface to cause axial movement of the tail.

8. A pump according to Claim 7 in which said tail lies substantially parallel to said surface in the operative position of the pin, said axis being disposed to one side of a plane normal to said surface through said inlet.

9. A pump according to Claim 8 including a further tail on said pin, said further tail being operative to prevent the first mentioned tail ieaving said surface.

10. A pumping according to Claim 6 in which said tail extends substantially normal to the remaining portion of the kin and in its operative position lies over said outlet, the pin being movable axially and then angularly to its inoperative position.

11. A pump according to Claim 10 including an eccentric washer secured to said pin, said washer in the operative position of the pin locating in a complementary shaped portion of the drilling, axial movement of the pin to the inoperative position withdrawing the washer from said shaped portion of the drilling to allow angular movement of the pin to permit the washer to rest on the housing of the pump and retain the pin in its inoperative position.

12. A liquid fuel injection pump for supply ing fuel to a combustion space of an internal combustion engine comprising the combination and arrangement of parts substantially as hereinbefore described with reference to Figures 1 and 2 of the accompanying drawings.

13. A liquid fuel injection pump for supplying fuel to a combustion space of an internal combustion engine comprising the combination and arrangement of parts substantially as hereinbefore described with reference to Figure 3 of the accompanying drawings.