US2908263A

US2908263A - Engine control

Info

Publication number: US2908263A
Application number: US762198A
Authority: US
Inventors: Hugh S Brown
Original assignee: Briggs and Stratton Corp
Current assignee: Briggs and Stratton Corp
Priority date: 1958-09-17
Filing date: 1958-09-17
Publication date: 1959-10-13
Anticipated expiration: 1976-10-13

Description

Oct. 13, 1959 H. s. BROWN 2,908,263

7 ENGINE CONTROL Filed Sept. 17', 1958 4 Sheets-Sheet 1 5 .H'u Z1 5. Brawn Oct. 13, 1959 H. 5. BROWN 2,908,263

ENGINE. CONTROL I Filed Sept. 17. 1958 4 Sheets-Sheet 2 FROM UNGROUNDED BREAKER POINT Oct. 13, 1959 H. 5. BROWN 2,908,263

I ENGINE CONTROL Filed Sept. 17, 1958 4'Sheets-Sheet s him-$47 Hugh 5'. Brawn H. 5. BROWN ENGINE CONTROL Oct. 13, 1959 4 Sheets-Sheet 4 Filed Sept. 17, 1958' ainuwfw ugh 5. Eva-awn United States Patent ENGINE CONTROL Hugh S. Brown, Wauwatosa, Wis., assignor to Briggs & Stratton Corporation, Milwaukee, Wis., a corporation of Delaware Application September 17, 1958, Serial No. 762,198

Claims. (Cl. 123-98) This invention relates to small, single-cylinder internal combustion engines of the type widely used to power lawn mowers and the like. Such engines are, of course, equipped with a carburetor having a throttle valve to control the flow of fuel-air mixture to the engine, and a choke valve to control the admission of air to the carburetor. In addition, they are usually equipped with an ignition grounding switch, by which the engine is normally stopped.

The purpose and object of this invention is to provide a simple, convenient control by which the throttle valve, the choke valve and the ignition grounding switch are all manually operable by a single lever or handle. The desirability of such a common control has been recognized in the past, but, heretofore, the attempts to meet this objective were rather involved and complex mechanisms, which not only seriously increased the cost of the engine, but, in addition, were unreliable. Accordingly, it is particularly an object of this invention to provide a control for the purpose described, which is characterized by extreme simplicity and reliable ruggedness as well as low cost.

Since pleasing appearance is an essential of engines of the type to which this invention pertains, it is now common practice to, at least partially, enclose the engine with a neat well-shaped covering, one wall of which forms substantially the top of the engine when it is used to power a lawnmower of the rotary type. With a view toward achieving utmost convenience to the user of such equipment, and further contributing to the appearance of the machine, it is another object of this invention to provide a good looking combination indicator and actuating lever or handle unit mounted upon this wall of the covering, whereby adjustment of the carburetor valves and the ignition grounding switch are readily actuated and the positions thereof visually indicated.

Still another object of this invention is to provide a control of the character described, wherein the operating speed range of the throttle valve is defined by detents cooperable with the combined handle and indicator.

Since the choke valves of carburetors in the past were usually spring biased to open position, they would sometimes stick and not open properly. To overcome this source of possible trouble, the invention has as a further object to provide a control of the character described which positively actuates the choke valve to its open position as well as to its closed position.

With the above and other objects in view, which will appear as the description proceeds, this invention resides in the novel construction, combination and arrangement of parts substantially as hereinafter described and more particularly defined by the appended claims, it being unde rstood that such changes in the precise embodiment of the hereindisclosed invention may be made as come within the scope of the claims.

The accompanying drawings illustrate two complete examples of the physical embodiment of the invention constructed according to the best modes so far devised for the practical application of the principles thereof, and in which:

Figure 1 is a perspective view of a single cylinder, aircooled, internal combustion engine equipped with the control device of this invention;

Figure 2 is a perspective view of the control device shown disconnected from the engine, but illustrating the same connected to the throttle and choke valves of the carburetor, to show the complete operative organization;

Figure 3 is a top plan view of that portion of the control which' is mounted upon the carburetor of the engine, with portions thereof broken away and in section;

Figure 4 is a perspective view of the combined indicator and actuating lever or handle for the control;

Figure 5 is a detail cross-sectional view taken through Figure 2 on the plane of the line 55;

Figure 6 is a side view of the complete control, illustrating a modified embodiment of the invention;

Figure 7 is a top view of the indicator portion of the control shown in Figure 6;

Figure 8 is a perspective view similar to Figure 2 to illustrate an alternate embodiment of the invention;

Figure 9 is a side view of that portion of the control shown in Figure 8 which is mounted upon the carburetor, with portions thereof broken away and in section, and showing the parts of the control in the positions they occupy to stop the engine;

Figure 10 is a side view similar to Figure 9 but show ing the parts in the full choke positions; and

Figure 11 is a detail cross sectional View through Figure 10 on the plane of line 11-11.

Referring now more particularly to the accompanying drawings, in which like numerals indicate like parts throughout the several views, the numeral 5 designates generally a single cylinder air-cooled, internal combustion engine of the type commonly used to power rotary lawn mowers. For this purpose, the engine operates with its crankshaft vertical and extending downwardly. It should be understood, however, that the invention is not limited to this specific engine type, though it is especially well adapted to such engines.

In keeping with the present trend towards improving the appearance of engines and the appliance and equipment powered thereby, it is now common practice to at least partially enclose the engine with a neat well shaped covering, as for instance, the cover 7 which forms, in effect, a continuation of the blower housing or shroud with which most air cooled engines are provided. Where the engine is of the vertical shaft type, one wall 8 of the cover 7 forms substantially the uppermost part of the engine. As such, the wall 8 is conveniently located to a user of the'lawnmower upon which the engine is mounted; the significance of which will be shown hereinafter.

The engine, of course, has a carburetor, indicated generally by the numeral 9, the tubular body of which is bolted to the engine cylinder over its intake port in the customary manner. An air inlet 10, usually equipped with an air cleaner 11 indicated indotted lines so as not to obstruct the more essential parts of the disclosure, provides for the admission of air into the carburetor,'and fuel is conducted thereto by a fuel line 12 which leads from the fuel tank.

Within the body of the carburetor is a choke valve 13 to control the admission of air, and a throttle valve 14 to control the flow of the fuel-air mixture into the engine. These valves are of the butterfly type, and each is mounted upon a shaft or stem which extends diametrically across the tubular body and is journalled in bearings in the opposite walls thereof. The stem or shaft of the choke valve has a lever 15 fixed thereto at its end facing the engine, and acting upon this lever is a torsion spring 16 which yieldingly holds the choke valve open.

The adjacent end of the shaft or stem of the throttle valve has a lever- 17 fixed thereto, and a tension spring 18 having one end thereof attached to the lever 17 draws the throttle valve toward its open position as long as the spring is under tension, but, as will be hereinafter shown, the spring 18 can also push the throttle valve to its substantially closed idling position. The usual air vane governor (not shown) is hooked to the lever 17, as at 19.

The choke valve, of course, is normally open and is closed only during initial starting of the engine, or more accurately, only when the engine is cold. The throttle valve, on the other hand, is very frequently adjusted since it is used to set the speed at which the engine is to run. Thereafter, the governor, coacting with the governor spring 18, adjusts the position of the throttle valve as needed to maintain that speed, despite variation in the load upon the engine. Accordingly, it has been customary to provide a conveniently located manual control by which the throttle valve could be adjusted, but no special provision has ever been made for adjusting the position of the choke valve, other than a tab or lug directly at or on the valve. This was an inconvenience and, to many persons unskilled in the operation of internal combustion engines, such a separate and rather inadequate control for the choke valve led to confusion and often resulted in total non-use of the choke and consequent difficult starting or operation of the engine with the choke valve partially closed.

Added to this source of confusion, was the fact that, heretofore, the ignition grounding switch by which the engine was intentionally stopped, usually consisted of nothing more than a flexible blade mounted adjacent to the spark plug, to be manually flexed and pressed against the center terminal of the spark plug.

The present invention completely eliminates this source of inconvenience and confusion, through the provision of a simple, reliable, inexpensive composite control, indicated generally by the letter A, by which the throttle valve, the choke valve, and also the ignition grounding switch are controlled from a single, manually operable lever or handle.

The main parts of the control A are assembled upon a mounting bracket 20 preferably formed as a stamping and channel-shaped in cross-section. The bracket is secured to the side of the carburetor body by screws passed through mounting lugs 20" so that the bracket is rigidly fixed with respect to the carburetor and, of course, is located directly adjacent thereto. Slidably mounted on the bracket is a carrier 21, also stamped from sheet metal and comprising a flat bar 22 disposed lengthwise between the opposite flanges of the bracket, and slidably received in slots formed in the legs of a U-shaped clip 23 fixed to one flange of the bracket. A small coiled spring 24 confined between the bottom of the mounting clip 23 and the adjacent side of the bar 22 frictionally holds the carrier against creeping from an adjusted position.

Extending upwardly from the bar 22 of the carrier and passing through an elongated slot 25 in the top of the mounting bracket, is an arm 26. The arm 26 provides the movable contact of the ignition grounding switch. The stationary contact is provided by a resilient blade 27 mounted upon, but insulated from the bracket 20 by a block of insulation 28. A conductor 27 connects the stationary contact with the ungrounded breaker point (not shown) so that, upon engagement of the arm 26 which is, of course, grounded, with the blade 27, the ignition circuit is disabled and the engine stops. Such engagement takes place when the carrier is moved to the end of its range of motion nearest the throttle valve, as shown in Figure 6.

The governor spring 18 is hooked to the arm 26 and, hence, the spring is under tension as long as the carrier 21 occupies a position in its range of motion along the bracket other than the position at which the ignition grounding switch is closed. In this latter position, the edge of the arm 26 facing the spring bears against the end of the spring 18 and actually pushes thereon to bring the throttle valve to its substantially closed idling position.

Near the outer end of the mounting bracket, that is, the end thereof remote from the switch blade 27, the side flanges of the mounting bracket have short slots 29 therein, and slidably received in these slots so as to extend across the bracket is one end 30 of a choke valve actuator link 31. The opposite end 32 of this link is connected to the lever 15. Accordingly, the torsion spring 16, which yieldingly holds the choke valve in its open position, holds the end 30 of the link in a position from which it may be moved by the arm 26 as the carrier is moved toward the outer end of the bracket, to draw the choke valve to its closed position. Hence, in the extreme outermost position of the carrier, the choke valve is closed. Preferably the actuator link 31 is formed of stiff wire.

Actuation of the carrier 21 to effect opening and closing of the throttle valve, the choke valve, and the ignition grounding switch, of course, can be made directly by grasping the carrier and shifting it endwise. However, from the standpoint of convenience, this manipulation is best achieved by means of an actuator lever or handle unit 35 mounted 011 the wall 8 of the cover 7.

The actuator lever or handle unit 35 consists essentially of a lever 36 medially pivoted, as at 37, to the lower end of an arm 38 projecting down from a quadrant-like mount 39, preferably formed as a die casting, and which, in turn, is fixed to the wall 8 of the cover over an opening therein with its arm 38 projecting downwardly through the opening. The upper end of the lever 36 projects through a slot in the arcuate top wall 40 of the casting 39 and has a handle 41 thereon; and a protrusion 42 on the lever 36 coacts with a pair of notches 43 in the lower portion of the mounting arm 38 to firmly and positively define the two positions of the lever 36, which correspond to the extremes of the operating speed range of the engine.

The lower or inner end of the lever 36 is connected to the carrier 21 by a link 45 so that, as thelever is swung about its pivot, the carrier is slid along the mounting bracket to effect adjustment ofthe throttle valve, the choke valve, and the ignition grounding switch. Preferably the link 45 is formed of wire, stiff enough, however, to transmit motion in both directions.

The different positions of the control are visually indicated by the position of the handle 41 at the outer end of the lever 36 with respect to a scale on the top wall 40 of the quadrant-like mounting casting, which scale is delineated with the designations Stop, Slow, Run, Fast, Start and Full Choke. The Slow and Fast positions are those defined by the detents 4243 and, hence, indicate the extremes of the normal running range. At each of these positions and, of course, all positions therebetween, the throttle valve, the choke valve, and the ignition grounding switch are open. In the Stop position, the ignition grounding switch is closed and the throttle valve is in its substantially closed idling position.

The Start position is substantially the same as the Fast run position, with no change in the disposition of the valves. The only change effected is an increase in the tension of the governor valve spring 18. This position is used in starting the engine when Full Choke is not needed, i.e. when the engine is not cold; and in moving from the Start position to Full Choke, the only change made is that the choke valve is closed.

Despite the ready accessibility of the actuating lever 36 and its handle 41, there may be instances in which it is preferable to have the actuator for the control located at some point remote from the engine. The present invention lends itself well to such installations, as shown in Figures 6 and 7, since, for such uses, it is only necessary to provide a Bowden wire type motion transmitting connection 50 between the carrier 21 and a conventional actuating lever unit 51. The sheath 52. of the Bowden wire is anchored, as at 53, to the bracket 20 and the adjacent end of its flexible wire 54 is hooked to the arm 26. The actuating lever unit 51, of course, may be mounted upon any suitable support as, for instance, the handle bars of a lawnmower.

If desired, the actuating lever unit 51 may be equipped with means to indicate the position of the throttle valve, but a more reliable indication is obtained by using the scale on the quadrant 39 and, to this end, the lever 36 is preferably replaced by a lever 36 which has no handle, but instead has a small indicator finger 55 on its outer end to coact with the scale. In this case, it is also desirable that the running range indicator detents 42-43 be omitted.

The advantage of using the lever 36' as an indicator in preference to an indicator on the actuating lever unit 51, resides in the fact that the lever 36 is directly and positively connected to the carrier 21 to always move in unison therewith, whereas any indicator carried by the actuating lever unit 51 would have to be set and the setting could very well be accidentally disturbed.

In the structure described, the choke valve is biased to its open position, and the carrier bar, which may be considered a control member, has a unidirectional driving connection with it. Although this arrangement is perfectly feasible, and normally satisfactory, it provides no assurance that the choke valve will open when the control is adjusted from Full Choke to Start. An accumulation of dirt might prevent the choke valve spring from fully opening the valve, or the spring itself might break. To overcome this possible source of trouble, the alternative form of the invention, illustrated in Figures 8 to 11, inclusive, provides means for positively opening the choke valve as well as positively closing it.

For this purpose the choke valve actuating link 31' is pivotally connected to the arm 26 of the control member or carrier bar 21, as at 64 The end portion of the link 31' thus connected to the control member, projects perpendicularly from the arm 26 through slots 29' in the upper edges of the side flanges of the mounting bracket as in the previous construction. However, it should be noted that the slots 29 are much longer than the slots 29 of the other construction, this being necessitated by the fact that the link 31 moves with the control member or carrier bar throughout its entire range of motion.

The extremity of the other end portion of the link 31' which is disposed at right angles to its portion that passes through the slots 29, is shaped to provide a hook 61, and this hook is received in an elongated slot 62 in a lever 63 fixed to the shaft of the choke valve 13. These parts are so proportioned that during adjustment of the control through its range extending from Start to Stop, the

- choke valve is in its open position, but during adjustment from Start to Full Choke, the lever 63 is swung to an upright position shown in Figure 10, to positively close the choke valve. In this respect, the alternate construction is no different from that previously described. The

difference resides in the fact that the choke valve is not.

biased to its open position, but is positively moved to that position during adjustment of the control from Full Choke to Start. This desirable result follows from the fact that the link 31 positively swings the lever 63 from its upright position shown in Figure to its substantially horizontal position shown in Figure 9. It should, of course, be appreciated that the slot 62 in the lever 63 is long enough to accommodate all back and forth adjustment of the control member between its Start and Stop positionswithout affecting the full open position of the choke valve.

The rest of the structure of the alternative embodiment of the invention illustrated in Figures 8 to 11, inclusive, is the same as that previously described.

From the foregoing description, taken in connection with the accompanying drawings, it will be readily apparent to those skilled in this art, that this invention provides a simple, reliable inexpensive control for internal combustion engines of the type widely used to power lawnmowers, and that, since it provides for the control of the throttle valve, the choke valve and the ignition grounding switch from a single, easily manipulated and conveniently located handle or lever, the invention is a great convenience to the ordinary lay person not familiar with the operation of engines, but who, through the widespread motorization of lawnmowers and garden equipment, finds himself in a position of having to operate such devices.

This application is a continuationin-part of application Serial No. 661,914, filed May 27, 1957, now abandoned.

What is claimed as my invention is:

1. In a single cylinder air-cooled internal combustion engine having a carburetor provided with a throttle valve to control the flow of fuel air mixture to the engine, and a choke valve to control the admission of air to the carburetor, said engine also having an ignition ground-ing switch, closure of which stops the engine, said switch comprising a stationary contact and a movable contact; a common control for said throttle valve, choke valve and ignition grounding switch comprising: a metal bar; means mounting the bar on the carburetor for lengthwise sliding motion between defined limits, said means electrically grounding the bar to the body of the engine; the stationary contact of the ignition grounding switch being live and comprising a spring finger and an insulated mounting therefor by which it is held in a position engageable by the bar as the bar is slid to one of its limits of motion, so that by sliding the bar to said position the ignition grounding switch is closed; an operative connection between said bar and each of said valves whereby lengthwise sliding of the bar between its defined limits efiec-ts opening and closing of said valves; a lever pivotally mounted upon a fixed part of the engine; handle means connected to the lever to enable manual manipulation thereof; and a motion transmitting connection between the lever and said bar so that by manual actuation of the lever, starting, running and stopping of the engine may be controlled.

2. In a single cylinder air-cooled internal combustion engine having an outer cover over a portion of the engine to enhance its appearance, said engine also having a carburetor provided with a throttle valve to control the flow of fuel-air mixture to the engine, and a choke valve to control the admission of air to the carburetor, and further having an ignition grounding switch, closure of which stops the engine, said switch comprising cooperating stationary and movable contacts; a common control for the throttle valve, the choke valve and the ignition grounding switch, comprising: a combined indicator scale and lever mounting member secured to the top of the engine cover, over an opening therein, said member having an upwardly facing surface with engine-condition indicating indicia thereon and having an arm projecting downwardly through the opening in the cover; a lever pivotally mounted on the lower end portion of said arm, and extending upwardly through the opening in the cover in juxtaposition to said upwardly facing surface to coact with the indicia thereon as the lever is swung about its connection with said arm; handle means outside of the engine cover operatively connected to said lever to swing the same on its pivot; and operative connections between said lever and the movable contact of the ignition grounding switch and each of the valves, so that by manipulation of said handle means to swing the lever from one posi tion to another as indicated by said indicia, the starting, running and stopping of the engine may be controlled.

3. In a single cylinder air-cooled internal combustion engine having an outer cover member over part of the engine to enhance the appearance of the engine, said engine also having a carburetor provided with a throttle valve to control the flow of fuel-air mixture to the engine, and a choke valve to control the admission of air to the carburetor, and the engine further having an ignition grounding switch, closure of which stops the engine, said switch comprising cooperating stationary and movable contacts; a common control for said throttle valve, choke valve and ignition grounding switch, comprising: a carrier for the slidable switch contact; means movably mounting the carrier adjacent to the carburetor and the stationary switch contact and constraining the carrier to linear motion along a path which carries the movable contact into engagement with the stationary contact; operative connections between the carrier and said valves so that said valves are controllable by movement of the carrier; means to show the positions of the valves and the movable switch contact comprising a scale on the exterior of said outer cover member over an opening therein, an indicator lever, and means pivotally mounting the lever medially of its ends for swinging movement about an axis at the underside of said cover member with the lever passing through said opening in the cover member to sweep across the scale as the lever is swung on its pivot; a motion transmitting connection between said lever and the carrier so that the lever swings about its pivot as the carrier is slid back and forth; and handle means drivingly connected with the carrier whereby the carrier may be shifted to control the starting, stopping and running of the engine.

4. The structure of claim 3 further characterized by the provision of cooperating detent means on the cover member and said lever, to define the running range of the engine.

5. In a carburetor for an internal combustion engine having an ignition system including a means for shorting the same to stop the engine, said carburetor having a body defining an air passage, a choke valve and a throttle valve in said passage, a common control for said choke and throttle valves and for said ignition shorting means comprising: a manually operable control member mounted on said body for movement back and forth between limits along a defined path, said control member engaging the ignition shorting means to stop the engine when the control member is moved to one of its limits; means providing a motion transmitting connection between said control member and the throttle valve through which movement of the control member effects opening or closing of the throttle valve depending upon the direction in which the control member is moved and by which connectionthe throttle valve is held closed when the control member is at its limit of movement at which it engages the ignition shorting means; and means providing a lost motion driving connection between the control member and the choke valve to positively close the choke valve during movement of the control member towards its other limit of motion and just before it reaches said other limit, and positively open the choke valve as the control member leaves said other limit.

6. The structure of claim 5 wherein said lost motion driving connection between the control member and the choke valve comprises a lever fixed to the shaft of the choke valve, said lever having an elongated slot extending lengthwise thereof; and a link having one end thereof pivoted to the control member and its other end hooked into said slot.

7. In a carburetor for an internal combustion engine having a body defining an air passage, a choke valve and a throttle valve in said air passage, said valves being of the butterfly type and being mounted to turn about parallel axes, the choke valve being biased open, a control for the choke and throttle valves comprising: a member mounted for linear motion along a path adjacent to the body of the carburetor and normal to the parallel axes about which the throttle and choke valves turn; a shoulder movable in unison with said member; a tension spring having one end connected with said member and its other end connected with the throttle valve, to yieldingly urge the throttle valve toward its open position with a force depending upon the position of said member with respect to the carburetor body; an abutment connected with the choke valve to move in unison therewith and positioned to be engaged by said shoulder upon linear motion of said member beyond a predetermined distance in the direction to increase the tension on the throttle valve spring, whereby a full choke setting of the carburetor valves is effected by such motion of the member; and means connected with said member and through which linear motion may be imparted thereto.

8. The structure set forth in claim 7 further characterized by the provision of an ignition grounding switch comprising a stationary contact mounted in fixed relation to the carburetor body and adjacent to said linearly movable member but electrically insulated from any grounded part so that said contact may be connected with the hot side of the engine ignition system, and a movable grounded contact normally disengaged from but engageable with the ungrounded stationary contact by movement of said member to a position remote from that at which it efiects closure of the choke valve.

9. In a carburetor for an internal combustion engine having a body defining an air passage, a choke valve and a throttle valve in said air passage, said valves being of the butterfly type and being mounted to turn about parallel axes, the choke valve being biased open, a control for the choke and throttle valves comprising: a mounting bracket fixed to the body of the carburetor; a bar endwise slidably carried by the bracket for movement along a path normal to the parallel axes about which the throttle and choke valves turn; a shoulder movable in unison with the bar; a tension spring having one end connected with the bar and its other end end connected with the throttle valve to yieldingly urge the throttle valve toward its open position with a force depending upon the position of the bar; an abutment connected with the choke valve to move in unison therewith, said abutment being positionedto be engaged by said shoulder upon endwise motion of the bar beyond a predetermined distance in the direction to increase the tension on the throttle valve spring, whereby a full choke setting of the carburetor valve is efiected by said motion of the bar; and means for moving the bar endwise back and forth.

10. The structure set forth in claim 9, further characterized by the fact that the mounting bracket has spaced apart apertured legs projecting from the bracket toward the carburetor body; by the fact that the bar is mounted by being slidably received in the apertures in said legs; and by the provision of a compression spring confined between the bar and a portion of the mounting bracket between said legs, said compression spring serving to frictionally hold the bar in a selected position of endwise movement.

References Cited in the file of this patent UNITED STATES PATENTS Eagon et al July 6, 1954 Richardson Feb. 17, 1959 OTHER REFERENCES