US2407013A

US2407013A - Fuel pump governor

Info

Publication number: US2407013A
Application number: US563587A
Authority: US
Inventors: Ifield Richard Joseph
Original assignee: Joseph Lucas Ltd
Current assignee: ZF International UK Ltd
Priority date: 1942-10-15
Filing date: 1944-11-15
Publication date: 1946-09-03
Anticipated expiration: 1963-09-03

Description

` Sept. 3, 1946. V uR, J, lFlELD 2,AQ7,013

FUEL APUMP GOVERNOR Filed Nov. 15, 1944 Patented Sept. 3, 1946 Richard Joseph rItielda Ealing, London, England, assigner .to Joseph Lucas Liitjd, Birmingham',

England Application November,

, 1944,` serial Np. r563.5287

In Grcatritain October 15, 1,942

2 claims. (C1. 121-38) `This invention relates to the governing means employed for automatically controlling the` output of a variable-delivery fuel pump used in conjunction with prime movers, the governing means being responsive to variable fluid pressure conditions.V In particular the invention relates to a governing means consisting of a spring loaded piston or diaphragm adapted to actuate the output controlling means of the pump, the piston or diaphragm being contained in a chamber. The piston (which term will hereafter be used as including also a diaphragm) is subject on both sides to the action of fluid pressure. Means are provided for effecting an unrestricted pressurefluid supply to one side of the piston, and Lthis fluid can also gain access to the other side through a restricted passage s o thatpressure differences can occur temporarily for actuating the piston, the pressures at the two sides being equal during a steady pressure condition in the system. At the side of the chamber opposite to that which receives the unrestricted fluid supply there is provided a release Valve which is responsive to any predetermined condition associated with the system, such as the speed of the pump. Govern-Y ing means as above described are hereinafter referred to as of the kind specified.

The above described governing means possesses the disadvantages that undesired pressure or volume fluctuations may be set 11p in the liquid delivered by the pump, and the object of the present invention is to enable this condition to be minimised in a simple and satisfactory manner.

The invention comprises the combination with a governing means as above described, of a variableevolume chamber arranged in communication with the valve-controlled side of the piston chamber, the Variable-volume chamber being such that it permits movement of the piston in response to a pressure change independently of the valve.

In the accompanying sheet of explanatory drawings:

Figure 1 is a diagrammatic sectional elevation of a liquid fuel pump embodying the invention.

Figure 2 is a fragmentary sectional side View illustrating a modified form of the invention.

The liquid fuel pump shown in the drawing comprises a rotary body part a arranged in a casing b and having formed around its axis a plurality of bores as c in each of which is arranged a reciprocatory plungerv d. The body part a is adapted to be driven in any convenient manner by the prime mover to be supplied with liquid fuel from the pump. During rotation of the body par-t a the plungers d are moved in one direction by an angularly movable swash plate e and thopposite direction by springs as f, the latter being situated in the bores c, and serving to hold an end falce of the body part in contact with aflat seating g` in the casing b. The swash plate e is of annularform and is pivoted at diametrical- 1y opposite positions to the casing b. The seating d isiorme'dwith a port h communicating With a liquid inlet i inthe casing b and with another y port y' communicating with a liquid outlet k: in

the @eine The body part a is adapted to serve also as a centriiugal'pump, and for this purpose is formed with an axial bore m which at one end communi- Cates with the inlet i through another port n in the Seating y, and at the other end communicates with a 'plurality of radial passages as o in the body part."`Liqi1id from the inlet i llows through thebore mand is expelled by centrifugal action through the radial passages o into the interior of the pump casing b around the body part a.

In one end of the casing b is formed a cylindrical chamber phaving closed ends. Within the chamber p is arranged a piston q loaded by a spring r, and extending from one side of this piston and through a bore in the casing b. at the inner end of the chamber is a rod s connected to the swash plate e. Instead of the piston a diaphragm may be employed, and as already stated I desire this alternative to be included in the terni piston. The inner portion ofy the chamber p, that is the portion at the piston rod side of the piston q, is 'n in'free communication with the outlet lc through a passage l in the casing b, and this portion 0f the chamber also communicates with the other or outer portion of the chamber (which contains the spring 1) through a restricted passage t. The cluter end of the chamber p is provided With a ventru which at its outer end forms a seating for a Valve u, this latter being responsive to any predetermined condition associated with the system.

`In the `example shown the valve 1f is formed or secured on one end'of a lever w, the latterbeing pivoted` at a positiontbetween its ends on the outer end of the chamber p, and being loaded by a spring :v which tends to hold the valve on its seating. The lever w is contained in a chamber y formed on or securedto the adjacent end of the casing'b, fand'this chamber communicates with the pump inlet i. The outer side of the chamber y is bounded by a controlling diaphragm z having `-at its centre an abutment 2 which is adapted to bear on the end of the lever w remote from the valve o. At the outer side of and bounded in part by the diaphragm z is another chamber 3, this latter being in communication with the above mentioned centrifugal pump through a passage l in the casing b. Also the diaphragm z is loaded by a spring 5 connected to an adjusting member 6, the latter being operable in any convenient manner by an attendant to vary the effect of the Sprlng.

Assuming the swash plate e to be in a position of maximum obliquity, that isto say the position in which the pump gives its maximum output, the swash plate will remain'in this position s0 long as the pressure in the chamber 3 (and thus acting on the controlling diaphragm a) is below some predetermined amount. In this condition the valve v is in its closed position and the liquid Likewise, if a pressure fall occurs at a sufficient rate liquid flows from the chamber 9 to the chamber p under the action of the spring loaded piston l0, and subsequently returns either in response to a pressure rise or to pressure liquid supplied to the end of the chamber p communicating with the chamber 9.

In the example shown in Figure 2, the passage l interconnecting the chambers p and 9 is controlled by a spring loaded Valve I2 which permits freeV flow of liquid from the chamber p to the chamber 9 but restricts the return ow. In other respects this example is similar to that shown in IFigure 1 with the exception that the restriction in the passage t interconnecting the ends of the chamber p is effected by a plug I3, suihcient v. clearance being provided between the plug and pressures at the two sides of the piston q are equal. But when the pressure acting on the diaphragm e exceeds the predetermined amount the diaphragm will move the valve v 01T its seating. The-liquid pressure in the outer portion of the piston chamber p will now fall and the piston q will be moved by the fluid pressure in the inner portion of the cylinder against the action of the spring r, so moving the swash plate e in the direction for reducing the pump output until a new condition of equilibrium is reached. If the valve o subsequently moves on to its seating as a result of the pressure on the diaphragm z falling below the predetermined amount, the liquid pressures at the two sides of the piston q again become equal, and the spring then serves to move the piston in the direction for increasing the pump output.

From the foregoing it Will be seen that as the position of the swash plate e is dependent on the pressure of the liquid in the chamber 3 and as this pressure is dependent on the speed of the pump, the latter is governed by the speed of the prime mover which drives the pump.

In carrying the invention into effect as shown in Figure 1, I connect the valve-controlled outer end of the chamber p by means of a passage 'l to One end of a small variable-volume chamber 9 containing a spring loaded piston I0 which controls the volume of the latter chamber, the other end of this chamber being in communication with the outer atmosphere through a vent Il. Under a steady condition in the system the piston q of the governing means remains at rest. But when a variation (rise or fall) of iiuid pressure occurs at a sucient rate the piston q can move in the appropriate direction in immediate response to the change and independently of consequential movement of the valve v, as liquid can now iiow between the chamber p of the governing means and the additional chamber 9 of variable volume. This liquid flow permits movement of the piston q of the governing means in response to pressure uctuations which are too brief to permit movement of this piston under the control of the valve o. It will be understood that when a pressure rise occurs at a suicient rate liquid flows from the chamber p to the chamber 9, this being permitted by movement of the piston l0 against the action of its spring loading, and if this pressure rise persists the valve v will be moved away from its seating, allowing return flow of liquid from the chamber 9 to the chamber p.

passage to allow a restricted flow of liquid through the passage.

By this invention the above mentioned disadvantage of the earlier form of governing means is effectively avoided.

This invention is not, however, limited to the particular examples described as constructional details may be varied to suit different requirements. Thus instead of the piston-controlled variable-volume chamber above described I may employ a chamber provided with a diaphragm and this may be loaded either by a spring or by gas under pressure; or I may employ an extensible closed chamber constructed from flexible material, for example, corrugated sheet metal.

Having thus described my invention what I claim as new and desire to secure by Letters Patent is: Y

1. Governing means of the kind specified, having in combination a fluid pressure responsive member, a main chamber containing said member, a passage for admitting an unrestricted supply of pressure fluid to said main chamber at one side of said member, a restricted passage for admitting pressure fluid to said main chamber at theother side of said member, a pressure-duid release valve situated at the side of said main chamber to vwhich pressure iiuid is admitted through said restricted passage, and a variablevolume chamber arranged in communication with the release valve side of said main chamber to permit movement of said member in response to a pressure change independently of said valve.

2. Governing means of the kind specified, having in combination a fluid pressure responsive member, a main chamber containing said member, a passage for admitting an unrestricted supply of pressure Huid to said main chamber at one side of said member, a restricted passage for admitting pressure fluid to said main chamber at the other side of said member, a pressure-fluid release valve situated at the side of said chamber to which pressure fluid is admitted through said restricted passage, a variable-volume chamber arranged in communication with the release valve side of said main chamber to permit movement of said member in response to a pressure change independently of said valve, and a second valve arranged between said main chamber and said variable-volume chamber, said second valve serving to permit free iloW of liquid from said main chamber to said variable-volume chamber, but to restrict iiow in the opposite direction.

RICHARD JOSEPH IFIELD.