US2693717A - Control mechanism - Google Patents

Description

Nov. 9, 1954 l F. A. scHlcK 2,693,717

CONTROL MECHANISM Filed 001'.. l2, 1950 .Nfl

United States Patent() CONTROL MECHANISM Frederick A. Schick, Springfield, Ill., assignor to Allis- Chalmers Manufacturing Company, Milwaukee, Wis.

Application October 12, 1950, Serial No. 189,834

3 Claims. (Cl. 74-531) This invention relates generally to control mechanism and is more particularly directed to means for releasably securing a control lever in any selected position.

In the use of hand control levers, particularly throttle levers on vehicles adapted for travel over rough terrain, it has been diicult to design a lever assembly which can remain fixed in any selected position despite the jarring movement of the vehicle and yet be automatically released for movement to a different selected position upon actuation by the operator of the vehicle. Generally, levers which are designed to withstand the rough movement of the vehicle require a positive locking means to hold them in a selected position and, accordingly, the locking means must be released before the lever can be moved to a new position.

It is the primary object of the present invention to provide an improved control lever mechanism comprising parts combined in a novel manner and including a rotatable drum, a lever fixed thereto, and a spring biased friction element coactable with the drum to xedly secure same against rotation yet permitting rotary movement of the lever and drum in response to actuation thereof by the operator.

A further object of this invention is to provide an improved control mechanism, as stated above, wherein the amount of force exerted by the spring biasing means is readily adjustable to provide a predetermined constant tension on the friction means.

Another object of the present invention is to provide an improved control lever mechanism having parts combined in a novel manner and including a rotatable drum, a lever xed thereto, a spring biased link operably connecting the lever to a device to be controlled thereby, a friction band coactable with the drum to iixedly secure same against rotation, and a spring means for adjustably securing one end of the friction band to a xed support with the spring means acting in opposition to the movement of the spring biased link.

And, accordingly, the present invention may be considered as comprising the various constructions and cornbinations hereinafter more particularly pointed out in the descriptive matter and claims, reference being had to the accompanying drawings, in which:

Fig. l is a diagrammatic view in side elevation of an internal combustion engine throttle control mechanism embodying the present invention;

Fig. 2 is an enlarged side view of a control lever assembly embodying the present invention with portions of the housing broken away to show the arrangement of parts within; and

Pig. 3 is a left side elevation of Fig. 2 with parts broken away and in section for sake of clarity.

Referring to Fig. 1, a schematic illustration of apparatus embodying the present invention shows the relationship of elements of a speed responsive governor and throttle control device for an internal combustion engine comprising generally a governor 1, throttle mechanism 2, and manual control means 3. More particularly, a pipe 6 represents the neck of an intake manifold for an internal combustion engine (not shown) which is provided with a throttle valve 7 controlled by variable speed governor 1. The governor mechanism comprises a rotatable shaft 8, a pair of flyweights 9, and a thrust sleeve 11 `slidably mounted on shaft 8 in coaxial relation thereto. A gear 12 is iixedly supported on shaft 8 for application vof power thereto from a rotary part (not shown) ,of the engine, and ilyweights 9 are pivotally 2,693,717 Patented Nov. 9, 1954 carried by shaft 8 for outward movement relative thereto upon rotation of the shaft. A supporting part 13, keyed to shaft 8, comprises a pair of oppositely extending arms 14 affording means for pivotally connecting an intermediate portion of yweights 9 thereto in outwardly spaced relation to the shaft. Moreover, llyweights 9 each include a portion 15 which is disposed for engagement with sleeve 11 in order that outward movement of the yweights may effect a shifting of sleeve 11 to the right (as viewed in Fig. l) and thereby rotate arm 16 in a clockwise direction about the axis of rotatable shaft 17 which xedly supports arm 16. The opposite end of shaft 17 has rigidly secured thereto a bell crank 18 comprising a irst arm 19 operably connected to throttle valve 7 through link 21 and lever 22, and a second arm 23 with the free end portion thereof carrying an adjustable screw 24 for engagement with an adjustable spring biased stop means 26.

Stop means 26 comprises a stud or pin 27 supported by suitable bearing means 28 for axial movement relative thereto, a washer 29 xedly positioned on the stud to limit movement to the right relative to bearing means 28, a coil spring 31 coaxially aligned with stud 27 with one end of the spring seated on washer 29, a cup shaped part 32 affording a seat for the free end of spring 31, and an adjusting lever 33 engaging part 32 for regulating movement thereof to selectively vary the compression of spring 31. An intermediate portion of adjusting lever 33 is pivotally secured to a suitable support 34 and the end of the lever remote from part 32 is connected by a link 36 to a manual control lever 37 for actuation thereby. It will be noted that link 36 is biased by a tension spring 38 to thereby exert a compressive force on spring 31 through lever 33.

Fig. 1 shows throttle valve 7 in closed position with governor llyweights 9 in their innermost position relative to shaft 8, t governor spring 31 compressed to exert a relatively large force on pin 27 thus preventing movement of arm 23 in a clockwise direction, and hand lever 37 in its throttle closed position. Assuming that gear 12 is being driven to rotate shaft 8, a movement of lever 37 to the left effects a corresponding movement of lever 33 to relax spring 31 and, consequently, pin 27 will be free to move to the left in response to force exerted by arm 23 of bell crank 18. And with pin 27 thus conditioned for movement, rotation of shaft 8 will cause an outward movement of yweights 9 thereby shifting sleeve 11 to the right and rotating arm 16 and shaft 17 in a clockwise direction. This rotation of shaft 17 causes bell crank 18 to also rotate with arm 23 and screw 2'4 moving stop pin 27 to the left and arm 19 moving to effect an opening of throttle valve 7.

It will be seen from the foregoing that the position of throttle valve 7 is dependent upon the condition of spring 31, as determined by the position of adjusting lever 33, and that, when Washer 29 is spaced from lixed bearing structure 28, any movement of lever 33 will result in an opening or closing movement of the throttle valve. And in order to prevent any shifting of lever 33, other than a deliberate movement through actuation of hand lever 37, a means now to be described has been devised for holding lever 37 xedly in position yet permitting movement thereof in response to pressure on lever 37 by the operator.

Looking now to Figs. 2 and 3 it will be seen that manual control means 3 comprises a housing 41 securable to a fixed support (not shown) by means of suitable fasteners insertable through openings 42 in ange 43 of the housing, a transverse shaft 44 rotatably mounted in bearing portions 46 which are centrally located in opposite side walls of housing 41, a drum 47 xedly mounted on shaft 44 within the housing, and hand lever 37 nonrotatably fixed to an outwardly extending portion of shaft 44, A friction means 48 is disposed within housing 41 for constant engagement with drum 47 and comprises a llexible band 49 having one end anchored to a pin 50 xed to the housing and the other end yieldably supported by an adjustable spring means 51, and a friction element 52 secured in any suitable manner (not shown) to flexible band 49 for frictional engagement with the peripheral surface of drum 47. And in this respect it will be noted that although drum 47 is shown as being made up of two circular channel-like members 53 with the web portions thereof secured together as by welling, any suitable type of drum construction may be use Adjustable spring means 51 comprises a cap screw 54, disposed through a bolt-receiving opening 56 in the upper portion of a continuation of flange 43 forming one end wall of housing 4l, with the threaded end portion 57 of cap screw 54 extending into the housing, a washer 59, coil spring 61, nut 62, and a guide element 63. The adjacent free end of band 49 has a generally rectangular shaped loop 64 formed therein with a circular opening through the band to slidably receive the shank portion of cap screw 54, and band 49 is then yieldably held in position along cap screw 54 by spring 61 which is positioned in coaxial relation to cap screw 54 and adjustably held thereon by nut 62. Washer 59 is provided to afford a seat for spring 61. Guide element 63, which includes a bolt-receiving opening therethrough, is preferably fixed to the inner end of loop 64, as by welding, and positioned on cap screw 54 to assure equal distribution of the force exerted by spring 61 on loop 64. And in this connection it will be noted (Fig. 2) that the longitudinal axis of cap screw 54 is substantially along a line tangent to the circumferential outer surface of band 49 and. consequently, the resultant force of spring 61 is also along this line. It has been found that such disposition of adjustable spring means 51 affords a uniform tension on band 49 and prevents any binding between drum 47 and friction element 52 which might otherwise prevent normal rotation of the drum upon actuation of lever 37 by the operator.

The head portion 66 of capscrew 54 contains a transverse opening (not shown) for receiving a fastening means therethrough, such as cotter pin 67, which may be secured at its free ends to lugs 68 projecting from the forward side of fiange 43 to prevent rotation of capscrew 54. It may be seen, therefore, that the compression of spring 61 may be selectively varied by removing pin 67 and turning the capscrew to shift same relative to nut 62. Replacement of pin 67 to its position shown in Figs. 2 and 3 will hold capscrew 54 and nut 62 in relatively fixed relation and provide a constant compressive force on spring 61.

Referring again to Fig. l it is seen that the illustrated embodiment of the present invention includes spring 38 which is acting in opposition to spring 61 of control means 3. That is, spring 61 is exerting a force to the left to wrap band 49 around drum 47 and provide frictional resistance therebetween, and spring 38 is constantly urging lever 37 and, consequently, drum 47 to rotate in a clockwise direction. Depending on the relative tension of the springs 31 and 38, more or less force will be required to move lever 37 to the right (closed position) than to the left (open position). If the throttle spring 31 is weaker than spring 38 it produces no change in the general effect of springs 38 and 61 just described. Preferably, spring 38 merely serves to bias the control means toward a closed position, but it may well be mounted in an obvious manner so as to urge lever 37 toward its open position or omitted entirely without materially affecting the real value of control means 3. If the spring 38 is made stronger than the throttle spring 31 it does afford an advantage, however, in that any tendency of drum 47 to creep due to vibration and shock is such as to close the engine throttle which is more desirable than having the engine speed up. It should also be noted with respect to the apparatus shown that the band may be reversed with respect to the drum and still afford a constant friction means for holding lever 37 in fixed position subject to automatic release upon movement by the operator.

The dash-dotted line 70 in Fig. l indicates the throttle opened position to which the hand lever 37 may be moved from its throttle closed position in which it is shown in Fig. l. The throttle spring 31 is subject to compression and expansion by back and forth movement of the lever 37 between its throttle closed and throttle opened positions, the compression of the spring 31 being relatively high, as pointed out hereinbefore, when the lever 37 is in the throttle closed position in which it is shown in Fig. 1. As a result of the compression of the throttle spring 31, the lever 37 is subject to a relatively strong torque which tends to move it in'counterclockwise direction from the throttle closed position in which the lever is shown in Fig. l, and it will be noted that the brake band 49 is also wrapped in counterclockwise direction around the brake drum 47.

The direction in which thebrake band 49 is wrapped around the brake drum 47 is significant for proper functioning of the mechanism. As shown in Fig. l, the brake drum 47 and brake band 49 cooperate to subject the control lever 37 to a first torsional drag of predetermined magnitude which opposes counterclockwise rotation of the lever, and to a second torsional drag of reduced magnitude which opposes clockwise rotation of the lever 37. The first mentioned torsional drag is normally effective to prevent the turning force produced by the governor control spring from rotating the control lever 37 in counterclockwise direction but is low enough to permit adjustment of the control lever from one position to another by application of a first manual adjusting torque thereto in throttle opening, counterclockwise direction. l

The mentioned second torsional drag, on the other hand, which opposes clockwise rotation of lever 37 and is of lesser magnitude than said first drag, permits adjustment of the control lever 37 from any rotatively adjusted position in throttle closing direction by application of a manual adjusting torque thereto in clockwise direction. The spring 38 is preferably arranged as shown so as to assist adjustment of control lever 37 in throttle closing direction and thereby reduce the manual torque required to compress the governor control spring 31 during throttle closing adjustment of the lever 37.

And although shown and described with respect to a throttle control mechanism, it is not intended to so limit the invention as other applications within the scope of the appended claims will become readily apparent to those skilled in the art. Other devices requiring constant retardation of movement between relatively movable parts may well employ the present teachings.

It is claimed and desired to secure by Letters Patent:

l. A control mechanism comprising in combination, a housing structure, a control element including a shaft extending into and rotatably mounted on said housing structure, a brake drum nonrotatably secured to said shaft within said housing structure, a brake band having an anchor point at one of its ends on and within said housing structure and extending from said anchor point around said brake drum within said housing structure, a bolt element mounted for rotation on a wall member of said housing structure and having a head portion outside of said housing structure and a threaded shank portion within said housing structure, a nut in cooperative engagement with said threaded shank portion, a coil spring positioned within said housing structure in surrounding relation to said bolt element between said nut and said wall member, and a loop member abutting said coil spring at the end of the latter remote from said nut and connected in load transmitting relation with said brake band at said other end of the latter.

2. A control mechanism as set forth in claim'l and further comprising releasable locking means cooperable with said head portion of said bolt element and with said housing structure for securing said bolt element against rotation relative to said housing structure.

3. The combination of a pivoted control element which is spring biased toward a limit position of adjustment, and an adjusting mechanism forsaid control element comprising a housing mounting said control element for rotation in one direction toward and for rotation in the opposite direction away from said limit position, a brake drum nonrotatably secured to said control element and disposed within said housing, a brake band Within said housing having an anchor point at one-of its ends on said housing and extending from said anchor point around said brake drum in said one direction, and resilient means within said housing operatively connected with said housing and with said brake band at the other end of the latter for maintaining said brake band in permanent frictional engagement with said brake drum, said resilient means including a bolt element mounted for rotation on a wall member of said housing and having a head portion outside of said housing and a threaded shank portion inside said housing, a nut in cooperative engagement with said threaded shank portion, a coil spring positioned within said housing in surrounding relation to said bolt element between said nut and said wall member, and a loop member abutting said coil spring at the end of the latter remote from said nut and connected in load transmitting relation with said brake band at said other end of the latter.

5 References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 320,419 Walters June 16, 1885 10 Number 6 Name Date Tampier Feb. 7, 1922 Wright Oct. 23, 1923 Barling Aug. 18, 1925 Olch Apr. 2, 1929 Le Tourneau Aug. 30, 1932 Johnson June 20, 1933 Scott May 27, 1941 Arens July 20, 1943 Heisel Dec. 23, 1947v

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