GB2266601A

GB2266601A - Governor mechanism

Info

Publication number: GB2266601A
Application number: GB9209560A
Authority: GB
Inventors: Peter Alban George Collingborn
Original assignee: Lucas Industries Ltd
Current assignee: ZF International UK Ltd
Priority date: 1992-05-02
Filing date: 1992-05-02
Publication date: 1993-11-03
Also published as: GB9209560D0

Abstract

A fuel injection pumping apparatus for supplying fuel to an engine includes a governor mechanism incorporating a pivotal lever (10) which is coupled to a fuel control member (17) and also to a centrifugal weight mechanism (12, 15) and a governor spring (16) so that as the speed of the associated engine increases the amount of fuel supplied to the engine will decrease. In order to adjust the droop of the governor a leaf spring (20) is provided. One end of the leaf spring is anchored to the housing of the mechanism and the other end engages the lever to assist the governor spring. The leaf spring is engaged by an abutment (25) which is adjustable generally along the length of the spring thereby to vary the spring rate of the two springs. <IMAGE>

Description

GOVERNOR MECHANISM This invention relates to a governor mechanism for a fuel pumping apparatus which is intended to supply fuel to an internal combustion engine, the mechanism comprising a lever pivotally mounted in a housing, a governor spring coupled to the lever, a centrifugal weight mechanism which is driven in use in synchronism with the associated engine and which is coupled to the lever to move the lever in opposition to the governor spring, and means operatively connecting the lever to a fuel control member of the pumping apparatus whereby with increasing engine speed the weight mechanism will move the lever in the direction to reduce the amount of fuel supplied to the engine and vice versa.

The governor mechanism can tssry the amount of fuel which is supplied to the associated engine between a minimum of value which may be zero, and a maximum value as determined by a maximum fuel stop and the variation in engine speed which has to take place to accomplish the aforesaid variation in the fuel supply is known in the art as the "droop".

The droop of the governor mechanism is determined by the effective rate of the governor spring and this is determined during manufacture of the spring. Although every effort is made to produce springs of the same rate there will nevertheless be differences which will result in variations in the droop between governor mechanisms incorporating the springs. When the engine is driving a vehicle it is desirable that there should be appreciable droop and slight variations in the droop although undesirable, will not matter too much. However, when the engine is employed in a "constant speed" application such for example when the engine drives an electric generator, the variation of engine speed with variation in engine load has to be very closely controlled.

It is desirable that adjustment of the droop should be possible whether or not the engine is in use and this is particularly so where two engines are driving respective generators which are connected in parallel, each engine having its own governor mechanism. Moreover, although the governor mechanism may be carefully set it can be expected that variation in the droop will occur as wear of the mechanism takes place.

The object of the present invention is to provide a governor mechanism of the kind specified in a form in which the droop can be readily adjusted.

According to the invention a governor mechanism of the kind specified comprises a leaf spring having one end anchored in the housing and its other end bearing against said lever at a position to assist the action of the governor spring, an adjustable abutment engaged with the leaf spring intermediate the ends thereof and means operable from the exterior of the housing for moving the abutment along the length of the leaf spring thereby to alter the combined spring rate of the two springs.

An example of a governor mechanism in accordance with the invention will now be described with reference to the accompanying diagrammatic drawing.

Referring to the drawing the governor mechanism comprises a lever 10 which is pivotally mounted intermediate its ends on a pivot diagrammatically illustrated at 11. At one end the lever engages a sleeve 12 which is axially moveable upon a drive shaft driven by the engine and which drives a high pressure fuel pump 13 having a plurality of outlets 14 which in use, are connected to the injection nozzles of the associated engine.

The sleeve 12 is acted upon by a plurality of centrifugal weights 15 which are mounted in a cage secured to the drive shaft and with increasing speed the weights urge the sleeve 12 towards the right as seen in the drawing, thereby imparting anti-clockwise movement to the lever 10 The end of the lever remote from the sleeve 12 is coupled to one end of a governor spring 16 shown in the drawing as a tension spring. The opposite end of the spring is connected to an adjustable lever whereby the force exerted by the spring can be varied. Although the drawing illustrates a tension spring, it could be replaced by a compression spring positioned on the opposite side of the lever.

The lever is coupled to a fuel control member 17 and this controls the amount of fuel which is supplied to the high pressure pump from a low pressure fuel pump 18.

Conveniently the fuel control member is in the form of an adjustable throttle. However, other forms of fuel control may be utilised if so required.

The mechanism is illustrated in its rest position and in this position the lever will be in engagement with a maximum fuel stop diagrammatically illustrated by the arrow 19. When the engine is started the engine speed will increase until a point is reached at which the force exerted by the governor weights overcomes the force exerted by the governor spring and this will cause movement of the lever in the anti-clockwise direction reducing the amount of fuel which is supplied to the engine until the engine operates at its governed speed as determined by the setting of the adjustable lever associated with the governor spring.If the load applied to the engine increases its speed will fall and the lever will then move in the clockwise direction to increase the amount of fuel which is supplied to the engine to restore the engine speed to close to its original value as determined by the setting of the adjustable lever.

As previously described the droop of the governor mechanism is determined by the effective rate of the governor spring and this is determined during manufacture of the spring.

In order to provide for an adjustment of the effective rate of the spring there is additionally provided and as shown in the drawing, a leaf spring 20 This is formed at one end with a foot 21 which is trapped between a location plate 22 and a surface defined by a part 23 of the governor housing. Conveniently the governor housing is an integral part of the housing which accommodates the low pressure pump and the high pressure pump. At its other end the leaf spring has a portion which is directed towards the lever 10 said portion terminating in a curl 24 which engages with the lever near to the point of connection of the lever with the governor spring. The curl may be replaced for example by a wear resistant button.

Also provided is an adjustable abutment in the form of a plate 25 and this engages the leaf spring 20 intermediate its ends. The plate 25 is carried upon a shaft 26 which is mounted in screw-thread engagement within a boss integrally formed with a cover 27 which is secured to the housing. The shaft 26 extends to the exterior of the housing and by virtue of the screw-thread engagement with the boss, angular movement of the shaft will adjust its axial setting. The plate 25 is loosely carried by the shaft but is restrained against angular movement with the shaft by means of a locating peg 28 which is carried on the locating plate 22.Although as shown, the intermediate section of the leaf spring 20 extends substantially parallel to the axis of the shaft 26, when the governor mechanism is in use and is controlling the speed of the engine the leaf spring will be stressed since the lever will have moved to an anti-clockwise position as compared with the position shown in the drawing. By moving the plate 25 the effective length of the leaf spring acting upon the lever can be varied and since the position of the plate can be adjusted from exterior of the housing, it is possible to adjust the effective rate of the combined springs while the engine is in operation and such adjustment can initially compensate for the manufacturing tolerances of the governor spring 16 and can also be used to compensate for wear which takes place during the use of the mechanism.

Although not shown in the drawing the leaf spring is tapered inwardly from the foot 21 to the curl 24 in order to maximise the allowable deflection of the spring.

Moveover, it is convenient for the taper to be applied to one side of the spring in order to provide clearance for various components of the governor mechanism.

Claims

1 A governor mechanism for a fuel pumping apparatus which is intended to supply fuel to an internal combustion engine, the mechanism comprising a lever pivotally mounted in a housing, a governor spring coupled to the lever, a centrifugal weight mechanism which is driven in use in synchronism with the associated engine and which is coupled to the lever to move the lever in opposition to the governor spring, means operatively connecting the lever to a fuel control member of the pumping apparatus whereby with increasing engine speed the weight mechanism will move the lever in the direction to reduce the amount of fuel supplied to the engine and vice versa, a leaf spring having one end anchored to a housing part and its other end bearing against said lever at a position to assist the action of the governor spring, an adjustable abutment engaged with the leaf spring intermediate the ends thereof and means operable from the exterior of the housing for moving the abutment along the length of the leaf spring thereby to alter the combined spring rate of the two springs.

2. A governor mechanism according to Claim 1 in which said abutment is in the form of a plate having an edge which engages the leaf spring, the plate being rotatably coupled to a shaft which is in screw thread engagement with a part of the housing and means operable to prevent rotation of the plate as the shaft is rotated to adjust the position of the plate relative to the leaf spring.

3. A governor mechanism according to Claim 1 or Claim 2 in which the leaf spring tapers from its one end to its other end