US2865623A - Hydraulic governor systems - Google Patents

Description

Dec. 23, 1958 c. wYNNE Y 2,865,623

HYDRAULIC GOVERNOR SYSTEMS 2 Sheets-Sheet 1 Filed April 19, 1955 Dec. 23, 1958 c. H. L. WYNNE HYDRAULIC GOVERNOR SYSTEMS Filed April 19, 1955 2 Sheets-Sheet 2 QQ EQ peed.

Qy/he United Patent HYDRAULIC GOVERNOR SYSTEMS Charles Horace Lionei Wynne, London, England, assignor to D. Napier & Son Limited, London, England, a

British company Application April 19, N55, Serial No. 502,268

Claims priority, application Great Britain April 26, 1954 5 Claims. (Cl. 264-14) This invention relates to improvements and modifications of the invention described and claimed in United States of America Patent No. 2,692,132, hereinafter referred to as the main invention.

The main invention relates to hydraulic governor systems of the kind comprising a positive displacement pump driven at a speed proportional to the speed of the engine, a leak valve-controlling the effective cross-section of the path by which fluid delivered by the pump can escape, aspeed control member associated with the engine, for example with the fuel supply to the engine, to control the speed thereof, and hydraulic apparatus responsive to pressure changes due to changes in the rate of delivery of the pump arranged to actuate the speed control member.

A hydraulic governor system according to the main invention comprises a positive displacement pump driven at a speed proportional to that of the engine, a working piston acting directly or indirectly on the speed control member of the engine, and acted upon by hydraulic fluid pressure derived from the pump, a leak valve arranged in the hydraulic circuit of the piston to control escapeof fluid therefrom and connected directly or indirectly with the working piston so as to be moved automatically in response to movements of the piston, means'for adjusting the datum setting of the leak valve to control the speed at which the engine'is to operate, and apparatus for preventing the supply of excess fuel to the engine at any settingof the governor apparatus, comprising a stop piston or the equivalent subject to a pressure dependent upon the engine speed, and means whereby such stop piston acts to resist or prevent movement of the speed control member in a direction to increase the fuel supply to the engine beyond a point which varies with and is determined by the engine speed.

In certain types of power plants when used for particular purposes it is desirable to be able to control the maximum output torque of the engine at dilferent engine speeds, and it is an object of the present invention to control-the movement of the stop piston such that at relatively low engine speeds a limitation is applied to the movement of the speed control member of the engine, and thus to the torque output of the engine, which varies as one function of the engine speed, while at engine speeds above a predetermined value the movement of the speed control member is limited to a value which is approximately constant, or varies as a different function of engine speed. It is a further object of the invention to control the movement of the stop piston such that at higher engine speeds above this predetermined value the movement of the speed control member is limited toa value which varies as yet another function of engine speed.

In the main invention the stop piston is double-sided and the sides of the piston are subject to the pressures respectively on either side of a pressure reduc ng valve between the displacement pump and the chamber on the first side of the working piston. The pressure reducing valve is so constructed that the pressure drop across the valve is proportional to the rate of flow through the valve, and thus to engine speed, while the stop piston itself is acted upon by a double-spring assembly so arranged that over the first part of the range of movement of the stop piston (corresponding to lower engine speeds) only one of such springs is operative, while over the remaining range both springs are operative. Such a double-spring arrangement provides some variation in the relationship between engine speed and the limiting position of the speed control member.

It has been found however that such a double-spring assembly is incapable of anything more than approximatev control of the position of the stop piston at different engine speeds, and is moreover diflicult or impossible to manufacture in compact form.

Now according to the present invention in a governor of the kind described and claimed in the main patent, including a pressure reducing valve between the delivery side of the pumpand the chamber on the first side of the working piston, the stop piston is double-sided and its two sides are subject to the pressures respectively on the two sides of the pressure reducing valve, the'pressure reducing valve being so'constructed that at low rates of flow through the valve (corresponding to low engine speeds) the valve presents a relatively restricted passage of fixed cross sectional area to the hydraulic fluid while at higher rates of flow the valve provides a progressively tional area of the Valve opening is limited to provide a relatively large fixed cross-sectional area opening at all rates of flow above an upper predetermined high rate.

At all engine speeds above this point the position of the stop piston therefore varies again relatively rapidly in relation to engine speed.

Preferably the valve includes a spring pressed movable valve element provided with at least one port constituting .a restricted aperture at low rates of flow, and a piston member subject to the hydraulic pressure from the delivery side of the pump and arranged to open a subsidiary port against the pressure of a valve spring as the pump delivery increases above a predetermined value.

According to another preferred feature of the invention the valve comprises a piston element formed with a radial flange portion seating on a fixed seating surface,

The invention maybe performed in variousditferent ways but one specific embodiment will now be described by way of example as applied to the particular governor.

system described in the specification of the main patent, for use with a marine propulsion power plant.

In the accompanying-drawings Figure 1 corresponds to Figure 2 of the main patent and illustrates only the pressure reducing valve, the stop piston, the main working piston and the leak valve, the remaining parts of the governor being unchanged,

Figures 2 and 3 are respectively a sectional side eleva tion and a plan view from underneath, both on an ou Patented Dec. 23, 1958 fromthe engine varies with variations in engine speed In' this'eXaIri-ple'the governor system is identical with the constr'uc tiondescribed in connection-with the maininve'n'tionwvith the exception of the stop piston'and ltS associated spring assembly, and of .lthe pressure reducing:

valve?" Themrodified pressure redu'cingvalve in accordance with the ipre'seut invention-comprisesa cylindrical valve sleeve 10 communicatingat its lower endwith the inlet an'nularl gallery 1 1 from the pump (not'shown) and atits upper end with an..outlet annular gallery 12 connected to the first (lower) side-.oflthe: working piston 13. A movable v'alve element 14 is arrangediat the upper end of valve-sleeve 10,- and is formediwith a radial circular flange 15 which seats on the upper lip of the sleeve. The radial flange 15 is formed with six orifice holes 16 spaced within its periphery which provide a restricted aperture for the passage of hydraulic fluid past the movable valve element when the element is seating on the lip of the valve sleeve 10. The valve flange 15 is subject on its underside to thepressure on the high pressure side of the valve and thus acts as a piston.

The'movable valve element 14 is mounted for axial sliding movement on a guide rod 17 extending through the valve sleeve 1 0 and located in an end piece 18 below theinlet gallery 11. The upper end of the movable valve element 14 bears on a compression spring 19which abuts against an abutment plate 20 located at the upper end of the rod 17. A pair of lock nuts 21 are provided on a threaded portion of the rod 17, above the valve elementv 14, to limit the upward movement or lift of the valve, and to enable this limit to be adjusted. When the now through the valve and hence the differential pressure across the valve rises above a predetermined value the valve element thus lifts against the spring pressure, and'provides an additional annular opening around the flange 15 lwhich constitutes a subsidiary valve port.

Thestop'piston 25 is provided, as in the main patent, with acentral well formation 26 in which slides the lowerend of a control rod 27 connected to a member 28 which is'arranged to control the fuel injection pumps of the engine. The lower end of the rod 27 is provided with an enlarged head or lock nut 29, so as to provide a lost-motion connection between the rod 27 and the piston 25; The upper side of the stop piston 25 is subject to the pressure in the outlet gallery 12 of the pressure reducingvalve 14. The lower side of the stop piston 25 communicates with the inlet gallery 11 through passages 30, 31, and is thus subject to the pressure on the inlet side-of the pressure reducing valve.

As in the main invention the working piston 13twhich isalso'connected to the control rod 27, is subject on its upper sideto fluid at working pressure which has passedinto a gallery 40'through a'pressure relief valve (not shown) arranged to maintain the balance pressure which acts on the lower side of this piston, at a constant value. The gallery 40 is'connected to relief or to a space atrelatively low pressure through a port 41 controlled by the leak valve 42 which is controlled by. a lever 43 pivo-- tally connected to the control rod 27, and bearing on the upperend of the valve 42, and pivoting at an intermediate point on anzadjustable fulcrum point 44. Adjustmentofi'thefulcrum 44 determines the datum setting of the's'leakvalve, and hence controls the selected power output of the-engine.

The'working piston 13 is mounted on the control rod 21am such amanner that'the piston is capable of movement upwards even when the rod 27 is halted by reason ofthe nut 29 engagingthe stop piston 25. For this purpose a collar 45 is secured to the rod 27 above the piston 13;aiid :a'scompressioh spring 46- abutting'against this collar tends to hold the piston against an abutment member 47 on the rod, while the piston itself-isfree to slide on the rod.

Whereas in the main invention a double-spring assembly acts on the upper side of the stop piston 25, in this present invention the assembly is replaced by a single compression spring 32 hearing on the upper side of the stop piston and abutting against a fixed flange 33 in the working cylinder. The position of the stop piston 25, and the limit of movement of the control rod 27, is thus controlled by the differential pressure between the two sides of the pressure reducing valve '14 acting against the compression spring 32.

At lower rates of flow through the valve 14, that is to sayat lower engine speeds, the movable valve element 14 remains seated on the lip ofthe valve sleeve 10, and the effective valve opening remains constant at the area of the orifice holes 16 in the valve flange. The difierential pressure across the-valve thus varies'approximately 'asthe square of the rate'of the 'flow'through the valve. The exact relationship between the limit'applied to thetorque output of the engine, and engine-speed, under these conditions, will however depend upon the exact shape'and dimensions of the parts of thevalve in relationship to the other parts ofthe apparatus. At engine speeds above a; predetermined value, which is determined by the spring" 19, the differential pressure on the flange 15 not the movable valveelement 14 progressively lifts this element 011 thevalve sleeve 1t? and provides a'progressively increasing additional. annular aperture aroundthe flange 15" through which fluid may flow. It will: be understood that thetlift of thevalve element increases progressively with creases in engine speed. At engine speeds above an upper:

predetermined value the movable valve element. 14 contacts the limiting abutment 21 on the guide rod 17 and the effective valve opening then remains constant for all? engine speeds above this upper predetermined-value. The: pressure drop across the valve thusrises again approxi mately as the square of the flow through the valve.

It will be understood therefore that a graphical repre.- sentation of the relationship between engine speed and,

the position of the stop piston 25 will be of stepped" appearance as shown in Figure 4. At low engine speeds,. the curve will be constituted by an approximately straight line A-B of steep gradient which is part ofa square law curve; at intermediate engine speeds the,

curve. will be constituted by an approximately straightline B-Cof relatively flat gradient, while over the upper range of engine speeds the curve will be constitutedby a third approximatelystraight line:CD of steep gradient, which also is part of a further square law curve. The. initial steep part A-B of the curve is designed to reduce.

the maximum permitted fuel. supply to the engine pro gressively as the speed decreases primarily in order to avoid excessive temperatures being created in the combustion zone of the engine, while the final steep part C -D is designed to increase the permitted setting of the engine fuel'supply apparatus at highspeeds in order to-compensate for mechanical and fuel losses which occur at high speeds. At all. engine. speeds below the value A themaximum permitted. fuel supply. is constant, this value being determined by the. setting of an. adjusting screw 48 which adjusts the lowest position of the stop piston.

The position of the stop piston 25 at difierent engine,

speeds thus corresponds very closely'to the ideal curve shown in chain lines in Eigure 4.

What I claim as my invention and desire to securebyfl Letters Patent is:

the working piston to control the escape of fiuid from the said circuit, the said leak valve being connected with the working piston so as to be moved automatically in response to movements of the piston to dampen the movements of the piston, means for adjusting the datum setting of the leak valve to control the speed at which the engine is to operate, and apparatus to limit the supply of fuel to the engine at any particular engine speed, comprising a double-sided stop piston lying in a cylinder with pressure chambers at opposite'sides of the piston, a pressure reducing valve in the hydraulic circuit of the working piston and between the delivery side of the pump and the Working piston, hydraulic connections to the chambers at opposite ends of the stop piston connected respectively to the hydraulic circuit on opposite sides of the pressure reducing valve, the pressure reducing valve having a relatively restricted passage of fixed cross sectional area which is open at all times to the hydraulic fluid, and an adjustable orifice controlled by pressure drop across the valve so that at higher rates of flow the valve provides a progressively larger opening, the said stop piston being arranged to resist movement of the speed control member, in a direction to increase the engine speed, beyond a point which thus varies with and is determined by the engine speed.

2. Hydraulic governor apparatus as claimed in claim 1 in which the maximum cross sectional area of the pressure reducing valve opening is limited to provide a relatively 6 largefixed cross-sectional area opening at all rates of flow above an upper predetermined high rate.

3. Hydraulic governor apparatus as claimed in claim 2 in which the pressure reducing valve includes a spring pressed movable valve element provided With at least. one port constituting a restricted aperture at low rates of flow, and a piston member subject to the hydraulic pressure from the delivery side of the pump and arranged to open a subsidiary port against the pressure of a valve. spring as the pump delivery increases above a predetermined value.

4. Hydraulic governor apparatus as claimed in claim 3 in which the piston member constitutes the movable valve element and is formed with a radial flange portion seating on a fixed seating surface, the flange portion being provided with at least one aperture constituting a restricted passage of relatively large cross section around the periphery of the flange. p

5. Hydraulic governor apparatus as claimed in claim 1 in which thestop piston is acted on by a single spring whose rate remains approximately constant over the whole travel of the stop piston.

References Cited in the file of this patent Tuscher July 31, 1956

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