US2222919A - Speed-sensitive governing means - Google Patents

Description

NOV. 26, 1940. G, J, TRAPP 2,222,919

'SPEED-SENSITIVE GOVERNING MEANS Filed Aug. 13, 1956 www@ Jgd f Patented Nov. 26, 1940 UNITED- sTATEs SPEED-.SENSITIVE GOVERNING MEANS George Joseph 4jlrapp, London, England, assignor to Automotive Products Company Limited, London, England Application August 13, 1936, 'Serial No. 95,947

In Great Britain August 13, 1935 claims. (ci. fzs-14o) 'This invention'relates to governing means operating by fluid pressure, and particularly to speed-sensitive governing means for injection pumps, and it has for its object to provide an 5 improved method of operation which .not only simplifies the general construction of governing means operated by uid pressure, but also provides advantages in practice, the foremost of which is the ready capability of altering the char- 1`0 acteristics of the governor to suit the injection pump or other mechanism which is being governed.

The invention broadly consists in the incorporation in a fluid-pressure operated governor,

of a movable plunger or equivalent which is acted upon by the pressure in question and which serves to controlor modify the passage of said iiuidthrough a constriction. Thus alterations in the pressure intensity of the fluid mayautomatically adjust the resistance-afforded by the Y constriction according to the actual position of the plunger or equivalent, this alteration being Y under the control of the designer to a very large extent, owing to the great number of modifications which can be made in theformation of the orice and the manner in which the characteristics thereof change in sympathy with alterations in the pressure .of the fluid. For this purpose the constriction is preferably provided between the plunger and a suitable housing accommodating said plunger,` the shape and proportions of the plunger being arranged in conjunction lwith the shape and proportions of the housing,

and the normal position of the plunger in respect to the housing being so designed, that changes in the fluid pressure bring about the desired movements ofthe plunger for actuating the usual controlling means, such for example as the rack bar or bars of a fuel injection pump. l l 4o The invention accordingly provides a govrnor device actuated by fluid pressure and comprising a passageway through whichV iiuid is caused to pass, and a movable plunger member disposed therein so as to produce a constriction, thus 5 creating a pressure difference on the two ends of the plunger and causing the latter to move along the passageway to an extent determined by the pressure of the fluid in advance of the plunger.

As a further feature the invention provides an improved arrangement and construction of fuel injection pump unit having a rotary feed pump driven by the usual cam shaft of the injection pump, a hydraulic governor fed from the delivery 55 of the feed pump and mechanism connecting said hydraulic governor with the usual controlling means, such as the rack bars of the fuel injection pump. Preferably the governor device comprises a plunger member which partially closes a passage fed with liquid from a pump driven 5 with the injection pump, movement of said plunger being arranged to control the delivery of the injection pump, and a relief valve, adapted to limit the pressure of the liquid acting on the back of the plunger member. This relief .valve 10 may serve also to increase the pressure of the liquid fed to the injection cylinders or equivalent as the speed of the pump increases.

Examples of the invention are shown in the accompanying diagrammatic drawing in which l5 Figure 1 is a side elevation partly in section showing a fuel injection pump fitted with the improved governor arrangement and pressure l relief valve;

Figures 2, 3, 4 and 5 show modified shapes of 20 passageway and plunger member;

Figure 6 is a fragmentary sectional elevation showing a further modification in the -design of the passageway and plunger member; and

Figure 7 shows in side elevation an alternative 25 form of packing for theplunger member.

In the arrangement shown in Figure 1 a twocylinder injection pump is indicated at I Il, and is provided upon the undriven end of its cam shaft Il with a feed pump I2 which is supplied 3o Y from a suitable reservoir (not shown) by means of a pipe I3, a filter I4 being included in the pipe I3, if desired. The delivery from the feed pump I2 is taken through a pipe I5 to a governor housing I6 secured at one end of the usual inlet 35 duct I1 of the pump, the inlet branches leading to the respective cylinders being indicated at I8 and I9 respectively. v

At the other end of the inlet duct I'I a relief or pressure-controlling mushroom valve 20 is fit- 40 ted in a guide 2|, and is normally held on its seating by a coiled compression spring 22 bearing upon an adjusting screw. The valve 2B serves to maintain a substantially constant pressure within the duct I1, as the feed pump I2 is pref- 45 erably arranged to have at any particular speed an output which is many times in excess of the quantity of fuel that could possibly be taken by the cylinders of the injection pump Il) with a view to providing powerful and eilicient governing; The excess fuel, therefore, passes through a pipe 24 and is returned to the feed pump inlet passage, which is indicated at 25. The valve 20 may if desired be formed with a comparatively restricted passageway along its At vits interior the governor housing I6 is formed with a cylindrical surface 26 Within which a plunger member 21 isdisposed, said plunger member being supported by means of a stem 28 which is slidably mounted in a well-fitting bush 29. Towards its outer end the stem 28 is-tted with an abutment washer 30 against which bears a comparatively light coiled compression spring 3|, the other end of the latter being carried by a cup-shaped intermediate member 32, the rim of which in turn engages with a stronger coiled compression spring 33 bearing at its other end upon the governor housing I6. Thus the plunger member 21 is normally drawn towards the left, although the position shown in Figure 1 is that which would normally be occupied while the pump is running at a speed corresponding to the idling speed of the engine. It will be seen that the plunger member 21 has its back part 34 substantially cylindrical in form, a slight clearance only being provided between this part and the interior surface 26 of the governor housing. At its front part, however, indicated at 35, the plunger member istapered so that as said member moves to the right the length of the constriction formed by the slight clearance between the part 34 and the bore 26 progressively diminishes, after which the tapered part 35 comes opposite the mouth 36 of the governor housing I6, thus causing the constriction to get larger in cross-sectional area as the plunger member 21 moves further to the iight. It will be appreciated that this movement is occasioned by the pressure developed as a result of fuel being forced through the restriction by the pump I2 and the actual movement will be a measure of this pressure. `Moreover, as this pressure is again dependent upon the speed at which the pump is driven it will be evident that the position occupied by the plunger member 21 will be that in which the pressure difference between the interior 31 of the governor housing I6 and the inlet conduit I1 produces a. force upon the plunger member 21 equal to that developed by the two compression springs 3| and 33, neglecting of course all frictional and other losses. It will be seen, therefore, that the plunger member 21 produces an eiect similarto that of a centrifugal governor, and it can be used for controlling the delivery of the injection pump for the purpose of providing steady running of an engine. In the example shown the stem 28 is iitted at its outer end with a transverse pin 38 which is engaged by the upper notched end of a lever 39, which is located by means of a slot 4I) which slides upon a spindle 4I, the lower end of the said lever 39 being in engagement with a pin 42 serving as the fulcrum of the lever. A further slot 43 engages a pin 44 carried upon the usual quantity control rod 45 of the injection pump, so that when the speed of the latter increases the upper part of the lever 39 is moved to the right about the pin 42, thus also moving the control rod 45 to the right and reducing the quantity of fuel injected. With a view to adjusting the speed of the engine the pivot pin 42 is itself mounted for angular movement about the spindle 4I, as indicated by the arrows.

The nature and the extent of movement of the plunger member 21 will, of course, to a large degree depend upon the shape of this member in relation to the interior surface of the governor housing I6, and various modifications are, therefore, shown in Figures 2 to 5 of the drawing. In Figure 2 the interior surface 26 of the governor housing I6 is again cylindrical but the plunger member 21 is formed at its front with a cylindrical portion 4,6, thus in effect slightly increasing the sensitivity of the governor at full load when the part 46 will, of course, be approximately opposite the mouth 36 of the housing I6.

yIn Figure 3 the plunger member 21 is tapered throughout its'entire length, and is arranged to engage with a correspondingly tapered surface 41 within the interior of the governor housing I6. In this example the clearance 48 between the overlapping parts of the governor housing I6 and the plunger member 21, progressively increases as the latter moves away from its inoperative position. A somewhat similar construction is shown in Figure 4, where the taper of the plunger 24 and the housing surface 41 is reversed with a view to providing increased sensitivity as the pressure increases, thus compensating for any falling off in the rate of increase of the feed pump delivery `as the speed increases.

A further modication is shown in Figure 5 where the major part of the plunger member 21 is cylindrical in form, but said member is provided upon its back portion with a flange 49 affording the desired small clearance, which is indicated at 50. As the speed of the injection pump increases the plunger member 21 is progressively moved against the action of its return spring until such time as the flange 45 projects beyond the mouth 36 of the governor housing, as indicated in broken lines, thus considerably reducing the sensitivity of the governor beyond this point.

Figure 6 shows a further constructional form of governor assembly, and in this case the plunger annular anges, indicated at 5U and 5I respectively, the desired small clearance being between the outer extremities of these anges and the interor surface of thegovernor housing I6. The stem 28 is formed with a pair of shallow grooves 52 serving to prevent leakage, while a fluid connection between the pipe I5 and the housing I6 is effected by means of a banjo connection 53 which is tightened axially on to the governor housing I6 by means of a nut 54. It will be seen in Figure 6 that the plunger member 21 is formed at its front end with a frusto-conical valve seating 56, which, when the governor is in its off position completely closes the inlet passage 51. Thus, should the plunger member 21 tend to stick after a period of disuse, the pressure generated by the feed pump will be ample to dislodge said member.

'I'he shape of the plunger member 21 and of the housing surface 26 may of course be varied in order to provide any particular form of characteristic for the governor, so that the injection pump unit as a whole may conform to the characteristics of the engine for which it is intended. Particularly is this the case where the improved fluid-actuated governor is used in conjunction with a governor according to our co-pending application No. 36,413, filed Aug. l5, 1935, issued May 24, 1938 as Patent No. 2,118,578 arranged to modify the timing of the injection in sympathy with the speed and load of the engine, in addisistant rubber or other appropriate material and having a relatively small diameter in order that the preponderance of pressure may act upon the member 21, is used for providing a liquid-tight joint which permits free sliding movement of the stem 28. It will, of course, be obvious that any other sliding packing such as those fof 'the cup leather type or the gland type may be used.

-The means used for controlling the governor, for example the two springs 3i and 33 shown in Figure 1, may be modified as desired, in accordance with the Work vto be carried out by the governor.

In Figure 1 the spring 3i is a light one to control the engine speed when idling, whilst the spring 33 is of much greater strength, and does not yield until the engine reaches the maximum speed at which' it is designed to run, so that the governor controls the idling speed and the maximum speed of the engine but is ineffective within the useful Working speed range of the engine. This form of governing is a normal requirement for transport engines.

As soon as the engine speed rises above'the idling speed the spring 3l yields, and the plunger member 21 moves inwardly until the abutment washer 30 contacts with the cup-shaped member 32, further movement being then prevented by the stronger spring 33 until the engine reaches its maximum speed.

For constant speed governing, such as is required for a marine engine, a single spring or its equivalent, which might be initially loaded, could be used as is common in governor practice.

Further, the present invention is not necessarily hunted to fuel injection pumps as it may be satisfactorily employed wherever there isa source of liquid, the pressure of which varies' according to the speed of the mechanism to be controlled.

What I claim is:

1. A fuel injection pump unit including, in

combination with a fuel injection pump having.

an inlet passage, a feed pump driven in cdmmon with the fuel injection -pump and a source of fuel, a governor including a housing having a bore provided with a cylindrical surface, said .bore communicating with the inlet passage, means connecting the bore with the feed pump,

a governor plunger axially shiftable within the bore. said plunger having a stem extending exteriorly ofthe housing and having a substantially cylindrical back portion and a tapered portion, said back and tapered portions being spaced from the cylindrical surface. and spring means on the plunger stem for normally urging said plunger stem in the boreaway fromv the inlet passage, said tapered portion and said Vback portion defining a constriction and receiving thereagainst fuel under pressure from the first mentioned means, said fuel under pressure shifting the plunger toward the inlet passage and against the tension of the means on the stem for maintaininga position of equilibrium for the plunger with respect to pressure dierences between the two sides of the plunger.

2. In a fuel injection pump unit, in combination with a fuel injection pump having an inlet passage, a feed pump driven in common with the fuel injection pump and a source of fuel, a governor including a housing having a bore provided with a cylindrical surface, said bore cornmunicating with the inlet passage, means for leading fuel from the feed pump to the housing, a governor plunger in the bore and having a back portion and a tapered portion dening a constriction in the housing, and means normally urging the plunger away from the inlet passage, fuel under pressure in the housing impinging on the tapered portion of the plunger and passing the constriction into said inlet passage causing shifting said plunger toward the inlet passage whereby a position of equilibrium for the plunger with respect to pressures at opposite sides of said plunger will be maintained.

3. In a fuel injection pump unit asrecited in claim 2, a relief valve in the inlet passage, and a v return pipe leading from the relief valve to the feed pump, said' relief valve maintaining fuel pressure in the inlet passage substantially constant.

4. In a. fuel injection pump unit, in combination with a fuel injection pump having an inlet passage, a feed pump driven in common with the fuel injection pump and a source of fuel, a governor including a. housing having a bore provided with acylindrical surface, said bore communicating with the inlet passage. means for leading fuel from the feed pump to the housing, a governor plunger in the bore and having a back portion Iand a tapered portion defining a constriction in the housing, means normally urging the plunger away from the inlet passage, fuel under pressure in the housing impinging on the tapered portion of the plunger and passing the constriction into said inlet passage causing shifting said plunger toward the inlet passage whereby a position of equilibrium for the plunger with respect to pressures at opposite sides of said plunger will be maintained. and means connected :with the plunger and operable by movement quantity control rod being carried by the fuel,

injection pump, a spindle, and a lever operatively connected with the fulcrum, the quantity control rod, the spindle, and the free end of the plunger stem.

GEORGE JOSEPH TRAPP.

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