US2569148A - Transmission control switch - Google Patents

Description

Sept. 25, 1951 L. D. BoYcE TRANSMISSION CONTROL SWITCH Filed June 21, 1945 FIG.3.

INVENTOR LEONARD D. BOYCE FIG.2.

Patented Sept. 25, 1951 TRANSMISSION CONTROL swITcn Leonard D. Boyce, Maplewood, Mo., assignor to Carter Carburetor Corporation, St. Louis, Mo., a corporation of Delaware Application June 21, 1945, Serial No. 600,722

1 Claim. l

This invention relates in general to control mechanism for automotive engine transmission systems of the character embodying over-drive gearing and over-drive throw-out provisions enabling vehicle drive transfer from over-drive to the manually controlled or more powerful transmission gearing. The invention is concerned more particularly with improved means for preventing operation of the over-drive throwout during vehicle travel at or in excess of a predetermined relatively high rate of speed, when over-drive throw-out, if permitted, would more or less seriously endanger the transmission gearing because of the resultant increased engine speed. This application is a continuation in part of my co-pending application Serial No. 378,651,

filed February 12, 1941, now Patent No. 2,396,551.

In automotive engine transmission systems of the character above indicated, the over-drive is engaged automatically when the vehicle exceeds a. predetermined rate of travel. It is desirable to include in the system, over-drive control provisions enabling ready transfer from over-drive to a more powerful gearing when power and fast acceleration are required, as for example, in passing another vehicle on the road. In one type of such control, a solenoid is energized in response to substantially full-opening of the engine throttle, to cause over-drive throwout. However, it has been found in practice that the vehicle drive cannot be safely returned from over-drive to the third or high gear when the vehicle is traveling at or in excess of a predetermined rate of speed, as at or' above 45 miles per hour.

According, it is a general object of the present invention to provide an improved and highly effective means for preventing over-drive throwout when the automotive vehicle is traveling at or above a predetermined speed, say 45 miles per hour. More specifically, the object of this invention is to afford in the control circuit of an over-drive throw-out solenoid, a switch of the general character appearing in my before mentioned Patent No. 2,396,551, but embodying certainv improvements thereover such as will increase the effectiveness of the switch to prevent 'solenoid energization and hence over-drive throw-out. when because of the vehicle speed, it is not safe to transfer from over-drive.

'A more detailed object is to provide a switch of the character indicated, which is jointly controlled by the carburetor throttle valve and a device responsive to engine developed suction in the; carburetor mixture conduit anterior to the throttle, the suction device being sensitive to the (not.v shown) degree of suction developed in consequence of engine operation at approximately the speed corresponding to vehicle travel at 45 miles per hour when it is undesirable to throw-out the over-drive, such as to render the throttle control ineilective to close the switch, and wherein the switch mechanism according to the present improvements, includes novel and effective provisions for causing a delayed or retarded response of the switch to the throttle control when tne latter is actuated, whereby to permit complete operation or full response of the suction control under certain hereinafter defined conditions.

Other objects and advantages of the present invention will appear readily from the following description of a presently preferred embodiment of the invention as illustrated in the accompanying drawing, in which:

Fig. 1 is a diagrammatic view showing portions of an automotive engine including the carburetor and transmission with the invention applied thereto Fig. 2 is an enlarged sectional view of a part of the carburetor and the switch device according to the present invention, as taken on line 2-2 in Fig. l;

Fig. 3 is a sectional view of the switch as in Fig. 2, but showing the switch contacts engaged; and

Fig. 4 is a sectional view similar to Fig. 3, but showing the switch contacts rendered ineffective to complete the over-drive throw-out circuit.

With reference now to the drawing and first to Fig. 1 thereof, there is shown at I0 a portion of an internal combustion engine of automotive type, including an intake manifold Il and carburetor indicated generally at I2. A clutch and selectively controllable or change speed transmission gearing of any suitable form, are located, respectively, in housings I3 and I4 secured to the rear end of the engine I0. The transmission system includes an over-drive mechanlsm or gearing located within a housing Il attached to or forming a rearward extension of housing I4 and connected to a propeller shaft I6 of usual form, extending to a driving connection with the rear axle of the automotive vehicle A solenoid device I1 mounted on theover-drive housing l5, functions in a known manner upon energization of the solenoid thereof. to throw-out the over-drive, and hence to Shift vehicle drive from the over-drive gearing to the third or next higher and more powerful gear ratio provided by the transmission gearing in housing |4. Control of the solenoid |1 is presently effected by an electrical circuit which includes a battery |3 having one terminal grounded, as at |3, and a switch device indicated generally at 23, mounted upon the carburetor l2. The battery and switch are connected to solenoid I1 by leads 2| and 22 respectively, the latter being connected to an insulated terminal 23 adapted to constitute the stationary contact of the switch 23 (Figs. 2, 3 and 4).

The detailed construction of the solenoid device and that of the over-drive gearing and other parts of the transmission, are not here illustrated, since such per se, form no part of the present invention. Although for present convenience, a manual shift lever 24 is shown for shifting the transmission gearing through the usual reverse, and first, second and third forward gears, it will be appreciated that such shifting may be effected in any other suitable manner. Moreover and as is well known, the over-drive portion of the transmission system is automatically engaged in response to a predetermined output speed of the transmission, or in other words, when for example, the vehicle attains a rate of travel of the order of 35 miles per hour.

The switch 20 as shown in detail by Figs. 2, 3 and 4, is of a character to afford joint control thereof by the engine throttle and a suction control operative to render the switch ineffective to energize the solenoid under predetermined suction conditions, as for the purpose hereinbefore indicated. The structure of the switch includes an angular body 33, the angularly related portions or legs of which are hollowed or longitudinally bored as indicated at 3| and 32. Hollow leg 3| forms a cylinder within which is slidably received a cup-shaped piston 33 normally urged downwardly in the cylinder by a coiled spring 34, the latter being engaged between the inner head surface of the piston and a shoulder 35 formed in the upper portion of the cylinder. A passage 33 connects the cylinder above the piston, to the interior of the carburetor mixture conduit preferably in the throat region of venturi 31 (Fig. 2). Venting the cylinder space below piston 33, is a port 33 which may open to atmosphere or lead to the air inlet horn of the carburetor, as desired. Secured to the lower head surface of the piston 33 is an angular spring member or clip 33, the downwardly projecting leg of which carries a metallic ball or contact element 43 which comprises in effect, the movable contact element of the switch. Through clip 33, the contact element 4|! normally or in its inactive position, is slightly spaced from the exposed inner end of the switch contact terminal 23 (Fig. 2). It is to be here noted that the body 33 of the switch is grounded through the carburetor,

intake manifold and engine block, and consequently in order to prevent a direct shunt of the switch contact elements 23 and 43, the piston 33 La formed of a suitable insulating material, while contact-terminal 23 is spaced from the switch body 33 by a suitable insulating bushing 4|. Also, in order to prevent rotation of the piston 33 and so as to maintain the ball contact 43 in proper alignment for engagement under certain conditions, with the switch contact 23, piston 33 is provided with an extension 42 suitably received in a guideway 43 in cylinder 3 I, the extension and guideway cooperating to determine non-rotative, linear movement of the piston, as well as to limit the downward movement of piston 33 to that lum- 4 cient to align the ball contact 43 with contact 23 (Fig. 2)

The hollow portion 32 of switch body 33, forms a second cylinder which is separated from the cylinder formed by the hollow body portion 3|, by a wall 45. Slidably received in the second cylinder is a piston member 43 provided with a forward projection 41 longitudinally bored as at 43. Piston projection 41 has its forward end received in an opening 43 in wall 4|, and is displaceable therethrough upon piston actuation in a manner presently to appear, for engagement with the ball contact 43 of the switch to move the contact to the left as viewed in Fig. 3. Such movement of the ball contact by projection 41, serves to determine engagement thereof with switch contact 23 or the adjacent exposed end of insulator bushing 4|, depending upon the positionment of the ball contact by the suction responsive piston 33 in response to certain conditions of engine operation as will be presently described.

A pin 53 has one end thereof slidably received in the bore 43 of piston projection 41 and its opposite end portion extending longitudinally through a closure member 5| secured to the body portion 32 and closing the end of the cylinder thereof. The pin 53 is urged outwardly or to the right as viewed in Fig. 2, by a coiled spring 52, while the piston 43 and its projection 41 are urged in the same direction by a weaker spring 53, so that a yieldable one-way connection thus results between the projection or switch actuator 41 (and piston 43) and the pin 50.

A principal feature of the present invention is found in the present provision for causing a predetermined delayed or retarded response of piston 46 to actuation of the pin 53 in the direction to telescope its inner end portion into the bore 43 of piston projection 41. Such pin actuation in the structure as thus far described, would serve to effect through the resulting compression of spring 52, inward displacement of the piston 43 and its projection 41, at a rate consequent only upon the compression differential of springs 52 and 53. Under certain conditions of engine operation to be related hereinafter, the almost immediate response of piston 43 may engage its projection 41 with ball contact 43 to displace the latter against the contact 23 before the suction control afforded by piston 33, can properly act to prevent such switch contact. Accordingly, the piston 43 rather tightly fits in chamber 54 to form a dash pot connected to atmosphere by the restricted orifice 55. The arrangement thus provides retarded movement of piston element 43 and hence a correspondingly retarded inward movement of switch actuating projection 41, to a degree determined in great part, by the calibrated port 55.

Pivotally mounted in the carburetor mixture conduit posterior to the venturi 31, is a butterfly throttle valve 33 which may be manually operated in the usual manner, by means of a suitable arm 3| (shown in part only) rigidly attached to throttle shaft 32. Formed on arm 3| is an extension 33 positioned to engage a stop 34 for determining the wide open position of the throttle valve, while a second extension 35 of arm 3| carries an adjustable screw 33 which through contact of its end 31 with stop 34, determines the closed position of the throttle valve. A third extension 33 of arm 3|, is provided for engagement with the exposed end of pin 50 when the throttle valve le substantially fully opened (me.

3 and 4), to displace the pin and thereby piston 46 and extension 41, inwardly so as to engage the latter with ball contact 40 and urge the contact in the direction of contact 23.

With further reference to the suction control, spring 34 is adjusted so as to maintain the piston 33 in its lowermost position, as in Fig. 3, when the suction at the throat of venturi 31 is less than approximately 1.8 inches of mercury, which corresponds with a vehicle speed of approximately 45 miles per h-our. When this degree of suction is exceeded at the Venturi throat, attendant upon a rate of vehicle travel in excess of 45 miles per hour, piston 33 will respond upwardly against spring 34, to a position of engagement with a shoulder 1l) formed in a wall of cylinder 3i, whereby to raise the ball contact 40 to a position (Fig. 4) wherein it cannot engage the contact 23.

In operation, when the transmission is in overdrive and the vehicle speed is less than 45 miles per hour, the elements of the switch device will assume the relative positions shown in Fig. 2, so long as the throttle is not operated to its fullopen position. Assuming now a demand for transmission shift from over-drive to a more powerful gear ratio, whereby to afford increased power and fast acceleration, the throttle is operated to approximately full open position so as to engage extension 68 with the pin 50 to displace the latter against its spring 52. In consequence thereof and as hereinbefore described, the extension or actuator element 41 will respond by inward movement retarded however, by the action of the pneumatic device constituted as herein described, but nevertheless ultimately effecting through the extension 41, engagement of the ball contact 40 with contact 23, whereby the circuit to the solenoid i1 will be completed to cause operation thereof to throw-out the over-drive. In the presence of such demand when the vehicle speed is substantially in excess of 45 miles an hour, throttle operation of the switch device in an attempt to throw-out the over-drive, will be ineffective to produce this result, because under this condition the suction control normally will have fully responded in a manner to lift the ball contact 40 out of registry with contact 23, so that displacement thereof by the piston extension 41 will engage the ball contact only with the exposed end of the insulator bushing 4I (Fig. 4). However, upon throttle operation of the switch as the vehicle speed becomes approximately equal to or tends to exceed only slightly the predetermined rate of 45 miles an hour, the present novel provision for delaying or retarding switch closing movement of the piston extension or actuator element 41, serves effectively to prevent entrapment of the ball contact 40 in a position of contact with switch element 23 before the suction device can operate fully, to lift or retract the ball contact. Such delay as before indicated, is afforded by the pneumatic device comprising piston 43 in chamber 54 and the associated calibrated vent port 55,v which determines the displacement rate of the piston 46 in the switch-operating direction, according to the rate of air discharge from the chamber through port 55 as predetermined by the port area. Thus through the port 55, the rate of movement of the switch actuator element 41 may be selected so as to assure a suiliciently delayed operation of the switch such as to afford under the foregoing conditions, a full response of the suction device to position the ball contact out of registry with the contact 23. Moreover, if while the vehicle is traveling at the critical speed, as miles an hour according to the presently selected example, there is a tendency for the vehicle speed to fall slightly below the critical at the moment the throttle is fully opened to produce switch operation, the present retardation of final switch actuation is equally effective to allow sufficient time for the spring 34 to move the suction piston 33 to its lower limit, whereby to align the ball contact 40 with the contact 23, for permitting ultimate switch closure and consequent solenoid energization to effect over-drive throw-out. It is to be noted also that the delayed or retarded actuation of the switch is of particular advantage in the event the suction piston 33 should become momentarily stuck when conditions demand its movement in response either to suction above the critical value of 1.8 inches of mercury, or to the return spring 34 when the suction is below the critical value, since if the throttle is fully opened at such time, engagement of the ball contact 40 by piston projection 41 will be sufliciently delayed to permit final positioning of the contact, providing of course, that the sticking of the piston 33 is only relatively momentary.

From the foregoing it now will appear that the present improvements provide a highly effective over-drive throw-out control switch mechanism which functions to cause transmission shift from over-drive upon demand therefor when the vehicle speed is below the indicated critical speed; to prevent such shift when the vehicle speed is in excess of the critical, andv to enable a full response of the suction control thereof either to prevent over-drive throw-out when the vehicle speed is approximately equal to or tends to exceed only slightly the critical speed, or to permit throw-out when the vehicle speed tends to drop slightly below the critical speed.

The invention may be modified in various respects as will occur to those skilled in the art, and the exclusive use of all such modifications as come within the scope of the appended claim is contemplated.

I claim:

In combination with an internal combustion engine intake conduit, a control switch including a body having a pair of chambers, one of said chambers having a pressure connection to said conduit, a pressure responsive device in said chamber operatively associated with said switch for effecting the operation thereof, a switch actuating plunger extending into the other chamber, an element on said plunger closely fitting said chamber for trapping a. body of fiuid therein, said second chamber and said element forming a dashpot contributing to coordinated action of said pressure responsive device and said plunger, and yielding means to move said plunger for operating said switch.

LEONARD D. BOYCE.

REFERENCES CITED The following references are of record in the file of this patent:

. `UNITED STATES PATENTS

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