US1650415A - Method of and mechanism for controlling variable-speed engines - Google Patents

Description

Nov. 22, 1927.

v E. J. ARMSTRONG METHOD OF AND MECHANISM FOR CONTROLLING VARIABLE SPEED ENGINES Filed March 1'7, 1922 4 Sheets-Sheet l 9 Fur?! Nov. 22, 1927. 1,650,413

E- J. ARMSTRONG METHOD OF AND KEGHANISM FOR CQNTROLLING VARIABLE SPEED ENGINES Filed March I7. 1922 4.She ets-Sheet 2 F/G 2a 2 7a o o f v 27 7 2 I I I:

awwmbo'a E. 1.. ARMSTRONG METHOD OF- ARD MECHANISM FOR CONTROLLING VARIABLE SPEED ENGINES Filed March '7. 1922 4 Sheets-Sheet 3 Nov. 22, 1927. 1,650,415

. E. J. ARMSTRONG METHOD OF AND MECHANISM FOR CONTROLLING VARIABLE swan ENGINES Filed March I7. 1922 4 Sheets-Sheet 4 Patents Nov. 22, 1927.

NITEJD STA EDWIN J. ARMSTRONG, OF ERIE, IPEN N SYLVANIA,WAS$IGNOR, BY DIRECT AND MESNE ASSIGNMENTS, TO ERIE STEAM SHOVEL COTKPANY, F ERIE, PENNSYLVANIA, A.

CORPORATION OF PENNSYLVANIA.

METHOD OF AND MECHANISM FOR CONTROLLING .VARIABLE-SPEED ENGTNES.

Application filed March 17, 1922. Serial in. 544,570.,

This invention is designed to improve the performance and efiiclency of flu1d-actuated engines, such as steam engines, and particularly high speed engines subjected to great I variations of load and speed'in their normal use, such for example. as holsting englnes with which the invention s particularly advantageous. In carrying out my invention I provide a speed sensitive ITXGChELDlSIIl which controls the point of cut-oii of the engine valve so that this point of cut-off is auto matically so adjusted as to get the greatest efliciency, or approximately so, for the speed at which the engine is running and also to give to the engine the greatestspeed for a narily so proportioned that with a late cut; off and an open throttle a lower speed is attained than with an early cut-oil 'under such conditions because the loss incident to expelling an over-supply of steam more than off-sets the added power of the power stroke.

The invention also results in a great saving.

of steam and gives tothe engine under ordinary conditions of operation higher speeds where desired. The invention also involves an improved speed, sensitive mechanism which is of peculiaradvantage for this pur pose. Other features and details of the i11 vention will appear from the specification and claims.

The invention is illustrated in the accompanying drawings as follows Fig. 1 shows arear elevation of a hoisting engine. 7

Fig. 1 a section through the valve chest showing the valve construction.

Fig. 2 aside elevation of the engine. Fig. 2 a section through the throttle valve. Fig. 3 av side elevation of the speed sensitive mechanism, a part being broken away to better show construction. i

Fig. 4 a central vertical "section of the speed sensitive mechanism.

Fig. 5 a section on the line 5-5 in Fig. 1.

Fig. 6 is a face View of the reversing slot.

Fig. is a diagramshowing the valve motiOIl.

1 marks the frame of theengine, 2the cylinders, 3 the crank shaft which is mounted 1n lWQEUHI gS 3? on the frame, tcr'anks mounted on the shaft 5 connectlng rods, 6 a

cross head to which the connecting rods ex- I tend. 7 guides and 8 the piston rod extendmg from the cross head to the usual piston 8. The engines are provided with the usual steam chests 9 in, which are arranged the usualvalves 9 operating on the ports 9 and the exhaust outlets 9 Steam is delivered to the steam chest through a pipe 10 and iscontrolled by a throttle valve 11 which has the sliding valve head 11 operating over the port 1O which in turn leads to the pipe 10. The valve is operated by a rock arm .12 mounted on a shaft- 12. The shaft is journaled in bearings 13. A rock arm l l'is fixed on the shaft 12. A link 15 extends fromthe rock arm 14 to a lever 16.

The lever 16 is mounted-on a pin 17 carried by theframe. A rod 18 leads from the lever 16 to a convenient point of control.

Tl'irough this-linkage it will readily be seen that the throttle may be. operated as de? sired. The exhaust is carried from the steam chest by way of the pipes 19 which unite in the exhaust pipe 20.

A gear 21 is fixed on the shaft 3 and drives a drum gear 22 of the usual construction which operates a drum 22 with the usual drum controls (not shown). The valves S are reciprocated by valve rods 23 which are secured to valve slides 24, the slides being mounted in guides 25 on the engine bed. A rod 26 extends from one of the slides and an eccentric rod 27 from the other of the slides. The rod 27 has an eccentric strap 28. 'The rod 26 extends to a rock arm 29 which is fixedon a shaft 30. The

shaft-.30 is carried in bearings 31 on the frame. A rock arm 32 is also fixed on the shaft BOand is connected by a link 33 with.

the eccentric strap 28. vThe purpose of this rock lever29 is to operate the valve so as to permit the cranks to be placed at an angle toeasch other in the ordinary manner.

.Thespeed sensitive, mechanism isshown in detail in Figs. 3. 4iand 5. It has a carriage S L which is fixed on the crank shaft by means ofa key 35. The carrier is made up ofthe two side arms 36 which are connected by yokes 37.

The eccentric 38 on which the strap 28 operatesis mountedon a pin 39. The pm 39 extends through bearings '40 in the arms 36.

' The weight rolls on the eccentric surfaces 50, these eccentric surfaces being opposed to each other made up of an arc of a circle on the center 50 and struck with a radius 50"50, the weight rolling on one of these surfaces with the engine running in one direction and operating on the other surface as indicated in dash lines Fig. 3 when running in the opposite-direction. The meeting points of the eccentric surfaces 50 at 50",

it will be observed, are farther from the -axis of the crank shaft than other points of said surfaces so that as the weight is retated with the shaft it tends to roll by reason of centrifugal force toward the point 50.

The eccentric surface is carried by a frame ;51 which is secured by screws 52 to the yokes 37 of the carrier. Spring yokes 53 are provided with the slots 54 which form a sliding fit with the cylindrically shaped lugs 49 on the arms 44. The yokes 53 are con- -.nected at their ends by the spring pins 55.

Springs 56 are provided with the eyes 57 which are arranged on the pins 55. The springs are mounted on a spring block 58,

this block being provided with arms 59 on which the springs rest and the springs be- 4 ferential slot 61.

ing secured to the block by means of bolts 60.

The spring block is 'journaled on the crank shaft and is provided with a circum- The outer face of this slot ,has a cylindrical surface 62 in which is arranged a spiral slot 63. A pin 64 operates in'this spiral slot and is carried by a reversing bar 65 which is slidingly mounted so as to move axially in the slot 65 in the car- Ilel arms 36. The bar65 is secured to a collar 66 slidingly mounted on the shaft 3. The collar has a groove 67 in which a ring 68 is mounted. Lever arms 69 are pivoted on trunnions 70 which extend from the ring 68. The arms 69 are fixed on a shaft 71; The shaft 71 is journaled in bearings 72. An operating lever 73 is fixed on the shaft 71 and operates over a segment 74 with the catch 74 by means of whichthe lever 73 .v maybe locked in opposite positions.

It will readily be seen that if the lever 73 is thrown it, operating through-the linkage which has just been described, moves the reversing bar 65 and the pin carried with this reversing bar operating in the spiral slot 63 throws the spring block 58 so as to carry the roller over one or the other of the surfaces 50 and as the roller is thrown from one of these surfaces to the other the arm 44 and with it the arm 41 is swung swinging the eccentric 38 so as to reverse the engine. Incidental with this'reversal of the engine it will be noted that the weight 45 will be operating on a reversed eccentric surface so that not only is the engine reversed but the speed sensitive mechanism is also reversed so as to operate perfectly with the reverse conditions. In Fig. 7 I show the diagram of the eccentric motion. In this A represents the center of the shaft, B the pivot upon which the eccentric swings across the shaft, and C the center of the eccentric when in the position shown in Fig. 3. The crank is in the line A-B. As the engine speeds up the centrifugal force of the weight 46 evercomes the resiliency of the spring 56 and moves the center C of the eccentric toward the line AB, the arc D-E representing its movement between the lowest and highest speed. The direction of rotation under these conditions is anticlockwise. The distance FG represents the lap of the valve so that the valve is open from the time the center of the eccentric at C crosses the line G until it again crosses it near C-something like three-fourths of the piston stroke. As the center of the eccentric C moves in toward the line A-B by reason of increasing speed, the arcduring which it is outside of the line G; becomes less and when it reaches the line E which is about its limit the valve barely crosses the line G and immediately recrosses it thus admitting a small quantity of steam and during a small portion of the piston stroke. \Vhen the device is reversed. the center of the eccentric goes to C, the direction being clockwise and the same effect by increasing the speed takes place, the maximum movement being indicatcd between D and E.

In the general operation of the engine, either going forward or back, the operator simply operates the throttle, opening it farther for a higher speed or heavier load and closing it for a slower speed or less load. In each instance the speed sensitive mechanism responding to this throttle opening and the load with the speed which follows such condition gives to the engine valve a cut-off for this particular speed and this cut-off will give the maximum economy for the speed and if a greater speed is required will give a cut-off which will accomplish the maximum speed which, as I have before stated, will be attained under ordinary conditions with a comparatively early cut-off. These conditions are ordinarily attained by a skilled locomotive engineer but in this in stance these conditions are attained by an loo of great frequency not only is there a greater certainty of the adjustment of the valve cutoff to accomplish the greatest economy, or' speed, but the operator is relieved entirely of this added attention.

It will be noted that the springs act as the centripetal element tending to move the weight along that part of the surface nearer the axis and that the weight operates as a centrifugal element tending to move to a position'away from the axis. It will also be noted that the springs '56 have such a variation of tension, or force that they do not operate to maintain the engine at a constant speed in the manner of an ordinary speed governor. Instead of giving a port opening to the cut-off valve which will bring the engine to a comparatively constant speed this device adjusts the port opening to the speed, the speed being controlled by the throttle. the spring being so adjusted relatively to the weight that the forces balance or there is an equilibrium at speeds throughout the range of speed to which the engine is designed to run. However, the invention may be measurably achieved if the range of control is through the most important parts of the working range.

What I claim as new is 1. In a controlling mechanism for fluid actuated reciprocating engines, the combination of an engine valve; devices actuating the engine valve; a c-entrifugally actuated speed sensitive mechanism responsive to the speed of the engine actuating said devices to vary the point of cut-0E of the valve as the speed varies; manually actuatedmeans independent of said devices for controlling the speed of the engine in the no 'mal working range of the engine; and means reversing the devices while leaving them subject to the influence of the mechanism. g

2. In a controlling mechanism for variable speed fluid actuated engines, the combination of a manually actuated controlling throttle valve controlling the admission of fluid to the engine to control the speed of the engine; an engine valve; a valve actuating device comprising a centrifugally actuated speed scntitive mechanism responsive to the speed of the engine actuating the engine valve to vary the cut-off as the speed varies;

and means for reversing said device while leaving it subject to the influence of said mechanism. j

3. In a controlling mechanism for fluid actuated engines the combination of a manually actuated throttle controlling the speed of the engine; an engine valve; a valve actuating device; a centrifugally actuated speed sensitive mechanism controlling the action of the device as the speed varies to vary the point of cut-off of the valve; and means for reversing-said device while "leaving it sub ject to the influenceof the mechanism.

4. In a controlling mechanism for fluid actuated engines, the combination of a manually actuated throttle controlling the speed of the engine; an engine valve: a valve actuating device; a centrifugally actuated speed sensitive mechanism controlling the action ofthe device as the speed varies to vary the point of cut-off of tlievalve throughout a major portion of the major part of the range of speed of the engine; and means for reversing said device while leaving it subject to the influence of the mechanism.

5. In a speed sensitive controlling mechanism, the combination of a carrier having an eccentric weight carrying surface; a valve actuating device mounted on the'carrier; a weight rolling on the carrier surface; a spring resisting the movement of the weight; means conveying the movement of the weight to the device comprising a swinging arm mounted on the carrier; and a trunnion on the weight engaging the arm.

6. In a speed sensitive controlling mechanisn'nthe combination of a carrier having an eccentric weight carrying surface; a valve,

7. In a speed sensitive controlling mecha nism, the combination of a carrier having an eccentric weight carrying surface; a valve actuating device mounted on the carrier; a weight rolling on the carrier surface; a spring resisting the movement of the weight; means conveying the movement of the weight to the device comprising a forked arm swingingly mounted on the carrier; inwardly extending slotted lugs on the forks; a pin inthe weight operating in the slots: and a, connection between the arm and said device.

8. In a speed sensitive controlling mechanism, the combination of a carrier having an eccentric weight carrying surface; a valve actuating devicemounted on, the carrier; a weight rolling on the carrier surface; springs resisting the movement of the weight; means conveying the movement of the weight to the device comprising a forked arm swingingly mounted on the carrier; inwardly extending slotted lugs on the forks; a pin in the weight operating in the slots; a connection between the arm and said device; and spring yokes engaging the lugs to which said springs are connected. I

9. In a speed sensitive controlling mechanism, the combination of a carrier having an eccentric weight carrying surface; a valve device comprising a actuating device mounted on the carrier; a weight rolling on the carrier surface; springs resisting the movement of the weight; means conveying the movement of the weight to the forked arm swingingly mounted on the carrier; inwardly extending slotted lugs on the forks; a pin in the weight operating in the slots; a connection between the arm and said device; and spring yokes engaging the lugs, said yokes being 7onnected by spring pins to which the springs are connected.

10. In a speed sensitive controlling mechanism. the combination of a carrier having an eccentric weight carrying surface; a valve actuating device mounted on the carrier; a roller weight rolling on the carrying surface; means for conveying the movement of the weight to the device comprising a forked arm having inwardly extending slotted lugs; a pin in the roller extending into the lugs; spring yokes engaging said lugs. said yokes having spring pins at each end; and springs resisting the movement of the weight secured to said pins.

11. In a speed sensitive controlling mechanism, the combination of a carrier having an eccentric weight carrying surface; a valve actuating device pivotally mounted on the carrier; a forked arm mounted concentric with the valve actuating device and connected therewith, said forked arm having inwardly extending slotted lugs; a weight between the forked arms rolling on said eccentric surface; a pin on the weight extending into said slots; spring yokes engaging the lugs; and springs connected with the yokes and resisting the movement of the weight.

12. In a speed sensitive controlling mechanism the combination of a carrier having opposed eccentric weight carrying surfaces thereon; a weight engaging said surfaces;

a spring resisting the movement of the.

weight; a valve actuating device controlled by the weight; and means for moving the weight on the surfaces to reverse the action of the weight on the device.

13. In a speed sensitive controlling mechanism the combination of a carrier having opposed eccentric weight carrying surfaces thereon; a weight engaging said surfaces; a spring resisting the movement of the weight; a valve actuating device controlled by the weight; and means for moving the weight on the surfaces to reverse the action of-the weight on the device and for reversing the action of the spring on the weight.

it. In a speed sensitive controlling mechanism, the combination of a carrier having opposed eccentric weight :arrying surfaces thereon; a weight engaging said surfaces; a spring resisting the movement of the weight; a valve actuating device controlled by the weight: and means acting through the spring for moving the weight on the surfaces to reverse the action of the weight and the spring to reverse the speed sensitive controllingmechanism.

15. In a speed sensit e controlling mechanism, the combination of a carrier having opposed eccentric weight carrying surfaces thereon; a weight engaging said surfaces; a spring arm secured to the weight; a movable mounting for the spring arm; and means for shifting the mounting to reverse the spring and the weight on the surface to reverse the speed sensitive controlling mechanism.

16. In a speed sensitive controlling mechanism the combination of a carrier having opposed eccentric weight carrying surfaces thereon; a weight engaging said surfaces; a spring arm secured to the weight; a movable mounting for the spring arm; means for shifting the mounting to reverse the spring and the weight on the surface to reverse the speed sensitive controlling mechanism comprising an axiallyanoving reversing device; and a spiral connection between the spring mounting and said reversing dev1ce.

- 17. In a speed sensitive controlling mechanism, the combination of a carrier formed with two sides and a frame carrying aneccentric weight engaging surface; a weight arrangement on said surface; a forked arm iournaled between the sides of the carrier in whichthe weight is mounted; a valve actuating device connected with the forked arm; a spring block concentric with the carrier; springs mounted on the block and resisting the movement of the weight; an axially moving reversing device mounted in the carrier; and a spiral connection between said device and spring block for reversing the same.

18. In a speed sensitive controlling mechanism, the combination of a centrifugal weight; a spring opposing said weight; a valve actuating device controlled by the weight; and means for reversing the spring and action of the weight on the valve aetuating device.

In testimony whereof I have hereunto set my hand.

EDWIN J. ARMSTRONG.

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