US3683874A

US3683874A - Valve actuating means

Info

Publication number: US3683874A
Application number: US70075A
Authority: US
Inventors: Martin John Berlyn
Original assignee: Individual
Current assignee: Individual
Priority date: 1970-09-08
Filing date: 1970-09-08
Publication date: 1972-08-15
Anticipated expiration: 1989-08-15
Also published as: GB1290628A

Abstract

Hydraulic actuating means for the spring-returned admission valve of a reciprocating expansion motor comprises a plunger pump delivering oil under pressure to a slave cylinder the piston of which is connected to said admission valve, an automatic nonreturn filling valve for said pump and controllable means for spilling oil displaced by the pump at any desired point in the delivery stroke of the pump plunger thereby determining the period of opening of said admission valve.

Description

United States Patent n51 3,683,874 Berlyn [4 Aug. 15, 1972 A [54] VALVE ACTUATING MEANS 2,602,434 7/1952 Barnaby ..l23/90.l2 I [721 Invent 9 ifi z 't gg gi FOREIGN PATENTS OR APPLICATIONS I I gland 1,172,416 10/1958 France ..l23/90.l2 [221 Filed= Sept 8, 1970 Primary Examiner-Al Lawrence Smith 21 APP] 70 075 Attorney--Norris and Bateman [57] ABSTRACT [52] US. Cl ..IZ 3/90.l2, l23/90.l6 [51] Int. Cl ..FOII 9/02 Y F actuating means f" the spnflg'retumed Search. 1 1 2 l 3 mlSSlOn valve ofa reclprocatmg expanslon mOtOl coma prises a plunger pump delivering; oil under pressure to [56] References Cited a slave cylinder the piston of which is connected to said admission valve, an automatic non-return filling UNITED STATES PATENTS vallve forl peudmtp agld controllabled means for spi ing oi isp ac y t e pump at any esired point 53: 2 In the dellvery strolte of the pump plunger thereby 1864 8/1935 z' dzltemunmg the period of opening of said admIssIon- 1,876,735 9/1932 Noble ..l23/90.l2 2,002,196 5/1935 Ucko ..123/90. 12 X 6 Claim, 2 Drawing Figures 4 l l- I 20 w v 1 I I 2% I i 29 .87 I l 37 T L3 u 1' ,a/jlml I {38 41/42 7 3g 1 F A 40 T 7- 3O 31 PATENTEDAUG 15 I972 3.683. 874 sum 1 or 2 FIG. 7.

INVESTOR MARTIN JOHN B! NORRTS 8| BATEI'HN PATENTEDMI: 15 m2 SHEET 2 0F 2 FIG. 2.

57 5a 56 s0 s1. 52

N (A) m INVENTOR MARTIN JOHN BLRLYN 74% w flaw NORRIS & BATmq q This invention relates to actuating means for the spring-returned admission valve of a reciprocating expansion motor of the type in which modulation of power output is effected by varying the period of time in each cycle of operation during which the admission valve is held open.

In the operation of reciprocating expansion motors it is known that the most efficient method of modulating the power output is to open the admission valve at a constant angle of the expansion motor crank and to vary or modify the crank angle at which the said valve closes, but heretofore no efficient mechanism has been devised for achieving this desired mode of control.

More particularly the invention provides an improved hydraulic valve actuating mechanism for use in these circumstances and which effects opening of the admission valve at a substantially constant angle of the expansion motor crank, whilst being controlled to close the valve at any crank angle up to about 120 from the angle at valve opening.

Another feature of the improved valve actuating mechanism is that through the greater part of the controlled range of crank angles at which valve closing can be caused to occur valve travel from closed position is substantially constant, whilst a further feature of this mechanism is that regardless of crankshaft speed a rapid valve closure is obtained over the normal range of valve open duration.

In the valve actuating means according to the invention a plunger pump, adapted to deliver oil under high pressure to a slave cylinder fitted with a piston having operable connection with the spring-returned admission valve, is provided with an automatic non-return filling valve and controllable spill means whereby oil displaced by the plunger may be spilled at any desired point in the delivery stroke of the plunger to a zone of relatively low pressure thereby determining the length of the period during which the admission valve is held open.

In the preferred embodiment the slave piston abuts a positive stop when at that end of its stroke corresponding to the closed position of the admission valve,the slave cylinder being provided with a spill port in its wall communicating with a sump and said spill port being so located as to be uncovered by the slave piston when the latter has moved from the positive stop by an amount corresponding to the travel of said admission valve from closed to full open" position.

Reference will now be made to the accompanying drawings which illustrate a preferred embodiment of the invention and wherein:

FIG. 1 is a sectional view of an expansion motor embodying the improved valve actuating means, and

FIG. 2 is an enlarged sectional view of said valve actuating means.

As shown in FIG. 1, the expansion motor comprises basically crankcase fitted with sump l 1 and supporting cylinder 12 which is closed by cylinder head 13.'

Piston 14 in cylinder 12 drives crank 15 through connecting rod 16, cylinder 12 being provided with a ring of exhaust ports 17 opening into exhaust manifold 18 having outlet 19. Cylinder head 13 is fitted with admission valve 20 for controlling flow of hot vapour under pressure from inlet 21 to admission port 22, admission valve 20 being urged towards its closed position by spring 23 and being opened by the valve actuator indicated generally at 26 and which will now be described with reference to FIG. 2.

The valve actuator includes pump plunger 27 having a fluid-sealing sliding fit in two

co-axial bores

28 and 29 in actuator housing 30, plunger 27 being driven on its pressure stroke by earn on camshaft 24 which is journalled in crankcase 10 (FIG. 1) and driven from crank 15 (FIG. 1), plunger 27 being returned on its suction stroke by spring 31. Plunger 27 is provided with peripheral groove 32, axial duct 33 and radial duct 34 which completes a fluid path from axial duct 33 to peripheral groove 32. Control sleeve 35 is a fluid-sealing sliding fit on pump plunger 27 and is provided with flanges 36 for engaging eccentric pin 37 formed on one end of control shaft 38 which may be rocked about its axis by control lever 39 fixed to the end of control shaft 38 remote from eccentric pin 37. Control shaft 38 is journalled in cover plate 40 of housing and inlet duct 41 in boss 42 of housing 30 conveys oil at a relatively low pressure, conveniently from the oil in the lubricating system of the expansion motor, into space 43 in housing 30. Annular valve 44 is urged towards concentric outer and

inner lands

45 and 46 respectively by spring 47 and between

lands

45 and 46 is annular groove 48 into which oil from space 43 can flow by way of ducts 49.

On the upper end of housing 30 is slave cylinder 50 connected byduct 51 and bore 52 to pump chamber 53 in which is located spring-loaded valve 44, said bore 52 being provided with annular groove 54 loading to duct 55 which conveys oil from said annular groove to a point from which it falls into sump 11 (FIG. 1). Slave piston 56 is a fluid-sealing sliding fit in bore 52 and is flanged at 57 to abut face 58 on slave cylinder 50 when slave piston 56 is fully retracted into bore 52.

The operation of the valve actuator is as follows: Plunger 27 moving upwards applies pressure to oil in pump chamber 53 and this pressure acting on slave piston 56 by way of duct 51 and bore 52 causes slave piston 56 to move valve 20 to the full open position shown in FIG. 1. Slave piston 56 having now uncovered the edge of annular groove 54, further upward movement of plunger 27 does not result in continued movement of valve 20 in the opening direction but causes oil to be rejected from bore 52 by way of annular groove 54 and duct 55 to sump 11 (FIG. 1). As plunger 27 continues to move upwards due to continued counterclockwise rotation of cam 25, peripheral groove 32 emerges from control sleeve 35. However, the oil pressure acting on slave piston 56 is sufficient to balance the force due to spring 23 and is much higher than the relatively low oil pressure in space 43. Thus the uncovering of peripheral groove 32 by control sleeve 35 results in slave piston 56 being forced back in bore 52 by spring 23, driving oil down axial duct 33 and, by way of radial duct 34 and peripheral groove 32, into space 43. Thus valve 20 (FIG. 1) is returned rapidly to closed position by spring 23 even though cam 25 is still moving plunger 27 in the valveppening direction, there being now insuflicient oil pressure acting on the slave piston to resist the valve closing action of spring 23.

It will be apparent that angular displacement of control level 39 will change the location of control sleeve 25 along the axis of plunger 27 and, if control sleeve 35 is raised to a higher location than that shown in FIG. 2, cam 25 will have to rotate further in a counterclockwise direction before peripheral groove 32 emerges from control sleeve 35 and allows valve 20 (FIG. 1) to close. Conversely, lowering control sleeve 35 causes valve 20 (FIG. 1) to close at an earlier point in the rotation of cam 25 than that shown. When the crest of cam 25 has passed through the centre line of plunger 27 the latter begins to descend. When flange 57 abuts face 28 further downward movement of plunger 27 causes a pressure drop in pump chamber 53 and this pressure drop over annular valve 44, and the pressure of oil in space 43, combine to create an upward force on valve 44 which, overcoming the downward force of spring 47, lifts valve 44 off

concentric lands

45 and 46 so that oil flows from space 43 into pump chamber 53 by way of ducts 49 and annular groove 48.

When cam 25 has rotated so far that plunger 27 is in contact with the base circle of cam 25, plunger 27 remains static in its lowest position for approximately a half a revolution of the camshaft and this gives spring 47 time to accelerate valve 44 back into seating contact with

lands

45 and 46 ready for the next cycle of valve actuation.

The volumetric displacement of plunger 27 over its full stroke is substantially in excess of, and preferably about two-and-a-half times, the volumetric displacement of slave piston 56 over its travel between abutment of flange 57 against face 58 of slave cylinder 50 and the uncovering of annular groove 54 of slave cylinder 50 by slave piston 56.

With control sleeve 35 in its highest position peripheral groove 32 does not emerge fron control sleeve 35 in any position of cam 25 and valve 20 (FIG. 1) does not begin to move towards closed position until the crest of cam 25 has passed through the centre line of plunger 27. This condition provides maximum duration of valve opening and would normally only be used for starting the expansion motor from standstill.

It will be noted that vertical adjustment of the position of control sleeve 35 affects only the closing point, that is the duration of opening, of valve 20 (FIG. 1). Regardless of the position of control sleeve 35 slave piston 56 will not move beyond the point at which spill into annular groove 54 takes place and therefore the distance by which valve 20 (FIG. 1) is lifted from closed position is dissociated from the duration of its opening. a

If it is a requirement that the expanion motor should be reversible, means may be provided for re-phasing camshaft 24 in relation to crank (FIG. 1).

I claim:

1. Hydraulic actuating means for a spring-returned admission valve of a reciprocating expansion motor comprising a slave cylinder, a slave piston in said cylinder operatively connected to said admission valve, a spill port in said slave cylinder uncovered by said slave piston at a point in its travel corresponding to the fully open position of said admission valve to thereby determine the stroke of said slave piston, pump means including a reciprocable plunger and a pump chamber connected to said slave cylinder, rotary cam means operable to initiate displacement of said plunger at a constant angular position of said cam means to deliver oil under pressure from said pump chamber to said slave cylinder, oil supply means, means connecting said oil supply means to said pump chamber and including an automatic non-retum filling valve for said pump chamber, said filling valve including an annular plate valve member spring-biased towards a closed position and movable to an open-position during the suction stroke of said plunger to deliver oil from said supply means to said pump chamber, and controllable spill means for spilling oil from said pump chamber, said spill means including adjustable means movable axially along said pump plunger and operable to spill oil from said pump chamber at any desired point in the delivery stroke of said plunger to thereby determine the duration of opening of said admission valve.

2. Hydraulic actuating means as defined in claim 1, wherein said controllable spill means comprises a transverse duct formed in said pump plunger and a passageway extending between said transverse duct and the delivery end of said plunger, and said adjustable means comprises a normally stationary control sleeve adjustable axially along said plunger and operable to uncover said transverse duct at a desired point in the delivery stroke of said plunger.

3. Hydraulic actuating means as claimed in claim 2 including a control shaft having eccentric means engageable with said control sleeve and means to turn said shaft and thereby displace said sleeve axially of said plunger.

4. Hydraulic actuating means as defined in claim 2, wherein said oil supply means comprises a low pressure oil chamber separated from said pump chamber by said annular plate valve member.

5. Hydraulic actuating means as defined in claim 4, wherein said annular plate valve member surrounds the delivery end of said pump plunger and controls the flow of oil through a passageway connecting said low pressure chamber to said pump chamber.

6. A reciprocating expansion motor comprising a crankcase, a cylinder mounted on said crankcase, a piston reciprocable in said cylinder, a crank drive connected to said piston, a spring returned admission valve for controlling the flow of fluid to said cylinder, hydraulic actuating means for said admission valve including a slave cylinder, a slave piston in said cylinder operatively connected to said admission valve, a spill port in said slave cylinder connected to said crankcase and uncovered by said slave piston at a point in its travel corresponding to the fully open position of said admission valve to thereby determine the stroke of said slave piston, pump means including a reciprocable plunger and a pump chamber connected to said slave cylinder, rotary cam means driven from said crank and operable to initiate displacement of said plunger at a constant angular position of said cam means to deliver oil under pressure from said pump chamber to said slave cylinder, oil supply means connected to said crankcase, means connecting said oil supply means to said pump chamber and including an automatic nonretum filling valve for said pump chamber, said filling valve including an annular plate valve member springbiased towards a closed position during the delivery stroke of said plunger and movable to an open position during the return stroke of said plunger to deliver oil from said supply means to said pump chamber, and controllable spill means for spilling oil from said pump chamber back to said oil supply means, said spill means including adjustable means movable axially along said pump plunger and operable to spill oil from said pump 5 chamber at any desired point in the delivery stroke of said plunger to thereby determine the duration of opening of said admission valve.

Claims

1. Hydraulic actuating means for a spring-returned admission valve of a reciprocating expansion motor comprising a slave cylinder, a slave piston in said cylinder operatively connected to said admission valve, a spill port in said slave cylinder uncovered by said slave piston at a point in its travel corresponding to the fully open position of said admission valve to thereby determine the stroke of said slave piston, pump means including a reciprocable plunger and a pump chamber connected to said slave cylinder, rotary cam means operable to initiate displacement of said plunger at a constant angular position of said cam means to deliver oil under pressure from said pump chamber to said slave cylinder, oil supply means, means connecting said oil supply means to said pump chamber and including an automatic non-return filling valve for said pump chamber, said filling valve including an annular plate valve member spring-biased towards a closed position and movable to an open position during the suction stroke of said plunger to deliver oil from said supply means to said pump chamber, and controllable spill means for spilling oil from said pump chamber, said spill means including adjustable means movable axially along said pump plunger and operable to spill oil from said pump chamber at any desired point in the delivery stroke of said plunger to thereby determine the duration of opening of said admission valve.

6. A reciprocating expansion motor comprising a crankcase, a cylinder mounted on said crankcase, a piston reciprocable in said cylinder, a crank drive connected to said piston, a spring returned admission valve for controlling the flow of fluid to said cylinder, hydraulic actuating means for said admission valve including a slave cylinder, a slave piston in said cylinder operatively connected to said admission valve, a spill port in said slave cylinder connected to said crankcase and uncovered by said slave piston at a point in its travel corresponding to the fully open position of said admission valve to thereby determine the stroke of said slave piston, pump means including a reciprocable plunger and a pump chamber connected to said slave cylinder, rotary cam means driven from said crank and operable to initiate displacement of said plunger at a constant angular position of said cam means to deliver oil under pressure from said pump chamber to said slave cylinder, oil supply means connected to said crankcase, means connecting said oil supply means to said pump chamber and including an automatic non-return filling valve for said pump chamber, said filling valve including an annular plate valve member spring-biased towards a closed position during the delivery stroke of said plunger and movable to an open position during the return stroke of said plunger to deliver oil from said supply means to said pump chamber, and controllable spill means for spilling oil from said pump chamber back to said oil supply means, said spill means including adjustable means movable axially along said pump plunger and operable to spill oil from said pump chamber at any desired point in the delivery stroke of said plunger to thereby determine the duration of opening of said admission valve.