US2130915A - Carburetor control mechanism - Google Patents

Description

Sept. 20, 1938. ,R. H. WHlSLER CARBURETOR CONTROL MECHANISM Filed Oct. 15, 1954 5 Sheets-Sheet 2 145 iarraeys.

Sept. 20, 1938.

R. H.-WHIS LER CARBURETOR CONTROL MECHANISM Filed Oct. 13, 1934 5 SheetsSheet 3 a .r. a 8 w a n hwfin m uhw W o; n -w J H g 3 h wwm R M wk 9 2 mm Kn r fin NM- Sept. 20, 1938. R. H. WHISLER 2,130,915

CARBURETOR CONTROL MECHANI SM Fil ed Oct. 15, 1934 5 Sheets-Sheet 4 y .zM cm-m Sept. 20, 1938. R. H. WHISLER CARBURETOR CONTROL MECHANISM Filed Oct. 13, 1954 5 Sheets-Sheet 5 In yen Zon- Zeal 9i? H Whig/e)" tiorzzeys.

Patented Sept. 20, 1938 GARBURETOR IMEGHANISM Ralph E. Whisler, Halfway, Mich, assignor, by

mesne assignments, to Carter Carburetor Corporation, St. Louis, Mo., a corporation of Delaware Application October 13, 1934, Serial No. 748,197

3 Claims,

This invention relates generally to carburetor control mechanism and has two principal objects of the type having a relatively high power-to-v weight ratio. Such vehicles have a desirably high rate of acceleration when the throttle valve is opened, but, on the other hand, when the throttle valve is completely closed, are often decelerated ata rate which, under many driving conditions, is undesirably rapid. In order to secure smooth operation the final shutting oil. of the power of the engine by the closing of its throttle valve should conform as nearly as possible to the natural loss of momentum of the vehicle; otherwise the progress of the car is likely to be characterized by sudden decelerations which are very disagreeable'to the passengers, particularly if the operator suddenly removes his foot from the accelerator pedal. Moreover, in cars equipped with vacuum operated automaticclutches, it is desirable to prevent a too sudden final closing of the throttle and consequent rapid engine deceleration, since under such conditions an undesirable delay in the disengagement of the clutch often occurs.

One of the objects of the present invention is to provide improved and relatively simple means, readily adaptable to conventional automotive power plants, for effectively retarding, without preventing, the final part only of the closing movement of the throttle valve.

A further object of the invention is to provide a delayed action throttle closing mechanism effective to accommodate the time lag in the disengagement of the vacuum controlled clutch when the accelerator pedal is entirely released thereby effectively synchronizing the disengagement of the clutch and the deceleration of the engine and effecting a uniformly smooth operation of the vehicle.

A further object of the invention is to provide an improved carburetor throttle valve closing means which preferably comprises what may be conveniently termed a primary mechanism for imparting to the valve only an initial range of closing movement and a secondary mechanism, operative independently of the primary mechanism, for imparting to the throttle valve a final range of closing movement, the secondary mechanism alone being controlled by a dash pot device whereby a delayed deceleration of the throttle valve is produced only during a predetermined range in its closing movement.

Other objects of this invention will appear in the following description and appended claims, reference being bad to the accompanying drawings forming a part of this specification wherein like reference characters designate corresponding parts in the several views.

Fig. 1 is a fragmentary view, partly diagrammatic and in section, illustrating portions of the carburetor, control mechanism and power plant.

Fig. 2 is a side elevation of the carburetor and associated parts.

Fig. 3 is a front elevation thereof.

Fig. 4 is a view similar to Fig. 2, looking from the opposite side.

Fig. 5 is a view similar to Fig. 3 with the float chamber partly in section and certain parts omitted.

Figs. 6 and 7 are views similar to Fig. 5 showing the parts in different positions.

Fig. 8 is a detail section taken substantially on the line 8-4, Fig. 3.

Fig. 9 is a detail section taken substantially on the line 99, Fig. 5.

Fig. 10 is a perspective view, in part diagrammatic, illustrating the carburetor and vacuum clutch assembly together with operating mechanism therefor.

Before explaining in detail the present invention it is to be understood that the invention is not limited in its application to the details of construction and arrangement of parts illustrated in the accompanying drawings, since the invention is capable of other embodiments and of being practiced or carried out in various ways. Also it is to be understood that the phraseology or terminology employed herein is for the purpose of description and not of limitation, and it is not intended to limit the invention claimed herein beyond the requirements of the prior art.

In Fig. 1 there is shown at A a portion of an automobile engine having a suitable number of cylinders l5, pistons l8, valves l1 and spark plugs l8, and an intake manifold 19 supplied with fuel mixture from a carburetor 20 under the control of a throttle valve II. The throttle valve 2! is carried by a rock shaft 22 having fast thereon an arm 23, pivotally connected through a link 26 to one end of a bell crank lever 25 pivoted at 24a to the manifold casing. The opposite end of this lever has an enlarged portion provided with an arcuate slot H of calculated length within which is slidingly connected for predetermined lost motion a pin it carried at the forward end of a link or push and pull rod 21. The opposite end Zla. (see Figs. 1 and 10) of this rod is pivoted to the outer end of an arm 25 fixed at its inner end to a rock shaft l3. Ihis shaft may be rocked through the medium of a conventional accelerator pedal 23 pivoted at 2311 to a bracket secured to the toe-board, the pedal being connected by means of a link 23 to a second arm I! fixed to the shaft. Suitable return springs 30 and 38 are employed to close the throttle and elevate the accelerator pedal when:

the latter is released by the driver.

The carburetor 20 herein shown (see also Figs. 2 to '7) for purposes of illustration'is, generallyspeaking, of a well known down draft type having a, float chamber 32 and a metering pin 33 for controlling the admission of liquid fuel from the float chamber 32 to the mixing chamber. The-metering pin 33 is carried by a lever 35 pivoted at 340 to a bracket 34l on the top of the float chamber and connected by a link 35 to an arm 36 fast on the throttle valve rock shaft 22, whereby the metering pin is retracted to open the fuel supply or advanced to close it simultaneously with the opening and closing of the throttle valve, respectively. The lever 34 is also connected with the plunger 31 of a fuel pump for injecting a priming jet of fuel into the mixing chamber when the throttle is opened. The carburetor shown is further provided with a choke valve 38 controlled by a thermostat 39'and also controlled from the throttle valve by engagement of a finger 40 on the lever 34 with an arm 4i on the choke valve stem, the arm 4|, in turn, acting through a lever 42, to control a movable stop 43 which cooperates with the lever 23 to limit the closing of the throttle valve 2|.

Except as hereinafter pointed out, or as they enter into combination with the parts hereinafter described, the parts above referred to specifically constitute no portion of the present invention and may be of any approved construction and arrangement.

In accordance with the present invention, the float chamber 32 has formed in the bottom thereof a dash pot cylinder 44. This cylinder may, if desired, be constructed separately and threaded into the bottom of the float chamber, but when in place constitutes a unitary part of the float chamber and is constantly supplied with liquid from the latter. Working in the cylinder 44 is a dash pot plunger 45 in the form of a piston comprising, in the present instance, an invcrted cup-shaped washer 46 carried by a rod 41 drilled to provide suitably restricted ports 48 communicating with the interior of the cylinder at opposite sides of the piston. Upward movement of the piston 45 is limited by shoulders 49 provided by a rib formed on the interior of the float chamber. At its upper end, the rod 41 is connected by a link 50 with the longer arm of a lever 5| pivoted at 52 to a. bracket 53 on the top of the float chamber. The shorter arm of the lever 5| is connected by a link 54 with a bell crank arm 55 pivotally mounted to turn freely on the throttle valve shaft 22 adjacent the arm 36, the arm 55 having a downward extension tle valve is nearly closed, is engaged by the top I of the stirrup portion 57 of the arm 35.

The position of the parts whenthe throttle valve is fully closed is shown in Figs. 3 and 5. To open the throttle valve and retract the metering pin 33, the throttle valve stem 22 is turned ina clockwise direction as viewed in the latter figures, thereby, through the arm 36, link 35, and lever 35 retracting or elevating the metering pin 33. During the initial portion of this opening movement the arm 55, under the influence of the spring 55, follows the movement of the arm 35, thereby, through the link 55 and lever 5i, raising the dash pot plunger until movement of the piston 45 is arrested by engagement with the shoulders 43. During this operation, the dash pot plunger offers no material resistance to the movement of the parts, since the top of the cylinder id is open to the float chamber 32. When the movement of the dash pot plunger is arrested by engagement of the piston 45 with the shoulders 59, as shown in Fig. 6, the movement of the arm 55 is likewise arrested, and during the further opening of the throttle valve the stirrup portion 5i of the arm 36 moves away from the lug 59 until the throttle valve has been fully opened as shown in Fig. 7. Thereafter the throttle valve may be opened and closed, and the metering pin advanced and retracted, between the positions shown in Figs. 6 and 7, without interference or modification of its action by the dash pot.

When the accelerator pedal 29 is released, the primary spring 35 and the secondary spring 3i, acting through the links and levers above described and the throttle arm 23 turn the throttle valve shaft in a counter-clockwise direction as viewed in Figs. 5, 6 and 7, thereby moving the throttle valve towards closed position and advancing the metering pin 33 downwardly toward the position for maximum restriction of the feed of the fuel to the carburetor mixing chamber.

During this closing movement, when the parts reach substantially the position shown in Fig. 6, the part 51 of the arm 36 engages the lug 59 on the arm 55. Movement of the latter in a counter-clockwise direction is resisted and retarded by the dash pot whose plunger is forced downwardly in the cylinder 44 by such counterclockwise movement of the arm 55. The final closing of the throttle valve, as well as the movement of the metering pin 33 into its fully advanced position, is thereby checked and retarded, so that the fuel mixture will continue to be admitted to the engine for a limited time in decreasing amounts substantially proportionate to the natural deceleration of the car, thus preventing the speed of the latter from being abruptly checked.

Referring to Fig. 1, when the accelerator pedal is fully raised as shown in said figure the rod 21 will have been moved forwardly (to the right in said figure) to the limit of its throw, this action being accomplished principally through the relatively heavy main or primary closing spring 3|. At this point the connection l4 of the rod will lie at the forward end of the slot, the throttle valve will be in its nearly closed position shown in Fig. 6, and the actuator part 51 will have reached a position substantially or nearly in engagement with the lug 58. Final closing movement of the throttle from this point is accomplished by the secondary closing spring 88, and it will be seen that when the rod 21 has thus reached the limit of its forward travel in closing direction, the bell crank lever will be free to turn further in a closing direction independently of rod 21 and spring 3|. This final range of closing movement of bell crank 24 (when the accelerator pedal 28 has been entirely released by the driver) is produced by tension spring 88 and is opposed by the dash pot. During this final movement the part 51 engages lug 58, swings the bell crank lever 55 about its pivot, raises link 54 and through lever 5| and piston rod 41 forces the dash pot piston downwardly within the cylinder against the resistance of the liquid therein, thus effectively retarding the final range of closing of the throttle between its positions shown.in Figs. 6 and 5. During this time the spring 58 is preferably free of tension. When the throttle valve has reached its final closed position, see Figs. 1 and 5, the pin M at the forward end of rod 2'! will occupy a position intermediate the ends of the slot ll, substantially as indicated in Fig. 1. Hence, the forward portion a: of this slot represents the allowable travel of bell crank 24 independently of the accelerator pedal connections, and consequently the corresponding independent travel of the throttle valve and dash pot piston. And only during this independent travel of the throttle valve does the dash pot function to resist the closing of the throttle and hence retard deceleration of the engine.

Referring to Fig. 10 it will be seen that the accelerator pedal 28 is connected through the medium of the rock shaft II with a vacuum operated unit connected to mechanism for actuating the clutch. This mechanism comprises a suitable cylinder 18 having mounted therein a reciprocating vacuum operated piston. A rod 1| is connected to the piston and is adapted to be reciprocated thereby. This rod is pivoted to a bell crank lever 12 which in turn is pivoted at 13 to a supporting bracket 14. A link 15 connects the bell crank 12 with a crank arm 18 attached to a. clutch operating rock shaft I! having the usual clutch throw-out fingers 18. The clutch unit proper is not shown herein since it may be of any conventional type. The connections between the accelerator pedal 28 and the vacuum unit comprise a crank arm 18 secured to the rock shaft l3, a link 88 connecting this arm with one arm of a bell crank lever 8| pivoted to a fixed bracket 82, and a link or rod 83 connecting the other arm of the bell crank 8| with a reciprocable plunger valve 84 operable within a cylinder .85 having an inlet port communicating through a pipe 86 with the intake manifold IS. The cylinder 85 has a port in communication with the cylinder "at one side of its piston and controlled by the plunger valve 84. Movement of the rod 83 in the direction of the arrow will shift the valve 84 into position to shut off the vacuum communication trol solely through the clutch pedal 88 and connections 8! between the clutch pedal and a crank' arm 82 secured to the rock shaft 11.

As abovestated, when the engine is idling with the throttle valve in its fully closed position the pin i4 will occupy an intermediate position within the slot I I, see Figs. 1 and 10. When, therefore, the accelerator pedal 29 is depressed the pin M will have a certain idle movement within the slot portion 11 before the bell crank lever 24 is moved, by the continued depression of the accelerator pedal, to open the throttle valve. idle movement, however, of the pin l4 within the slot ii, the connecting rod 83 and vacuum control valve 84 will be retracted so as to close or partially close communication between the intake manifold and the cylinder I0. Thus, the initial opening of the throttle valve by depressing the accelerator pedal is delayed during a predetermined interval of time to permit independent closing movement of the vacuum control valve 84. It has been found that a certain time lag occurs in the engagement of the clutch by the clutch return spring, and this time lag is accommodated by providing the delayed opening of the throttle valve when the accelerator pedal is depressed. This delayed action, however, is not sufficient to prevent the throttle valve opening in time to cause the engine to accelerate and its speed to equal or exceed the car speed to the desired degree when the clutch becomes engaged. From the foregoing it will, therefore, be seen that a lost motion of the actuating rod 21 occurs when the accelerator pedal is initially depressed, permitting an initial independent movement of the vacuum control valve 84 before the throttle valve opens, thereby offsetting the time lag in the vacuum cutting-out within the cylinder 18 preparatory to engagement of the clutch by the clutch return springs.

It will also be seen that the dash pot retarding device as well as the lost motion connection I4, I l performs an important function in cooperation with the automatic vacuum "controlled clutch mechanism for producing a properly timed disengagement of the clutch during deceleration of the engine when the accelerator pedal is released. It has been found that when the control valve 85 is shifted, upon release of the pedal 28, to open vacuum communication between the cylinder I8 and intake manifold a certain time lag or delay occurs in the vacuum becoming effective to retract the piston within the cylinder -18 and thereby to disengage the clutch ,(against the resistance of its return springs) through the mechanism ll-I8. This time lag has resulted frequently in undesirably delaying the clutch disengagement upon rapid engine deceleration resuiting often in noticeable jerks and backlash which are objectionable to the passengers. In order to overcome these disadvantages I have provided means whereby the vacuum control valve will be opened and the clutch disengaged before the throttle valve has finally closed and before there has occurred during deceleration such a change in torque conditions as to produce the above mentioned objectionable effects. These improvements in operation have preferably been accomplished, by virtue'of the present invention, first, by imparting to the throttle valve a final range of closing movement after the vacuum control valve has completed its opening movement, and, second, by retarding this final closing movement of the throttle, thus offsetting the time lag in the vacuum mechanism becoming During this eifective to disengage the clutch. As a result, the clutch will disengage before an approximate point has been reached during the deceleration of the engine where the car tends to drive the engine. From the foregoing, therefore, it will be seen that no undesirable delay in the clutch disengagement occurs when the accelerator pedal is suddenly released and the engine decelerated.

I claim:

1. In a motor vehicle having an engine, in combination, a carburetor for supplying fuel mixture to the engine, said carburetor having a float chamber, a throttle valve for controlling the admission of fuel mixture from the carburetor to the engine, a dash pot comprising a cylinder communicating with said float chamber and a plunger in said cylinder, means for moving the throttle valve toward closed position without moving said plunger, and means for simultaneously closing the throttle valve and moving said plunger independently of said first named means.

ma am 2. The combination of a carburetor having a throttle valve, means for actuating said throttle valve, a retarding device, means for actuating the retarding device independent of said throttle valve actuating mechanism, means for moving said retarding device to operative position, and means for connecting the retarding device to the throttle valve during the final portion of its closing movement for retarding the latter.

3. The combination of a carburetor having a throttle valve, means for actuating said throttle valve, a retarding device, means for actuating the retarding device independent 01' the throttle valve actuating mechanism, means for moving said retarding device to operative position controlled by the throttle valve actuating mechanism, and means for connecting the retarding device to the throttle valve during the final portion of its closlng movement for retarding the latter.

a H. LER.

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