US 2235797 A
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Description (OCR text may contain errors)
March 18, 1941. H. A. CARLSON 2,235,797
ACCELERATING PUMP Filed May 6, 1938 FIG.3. 7
INVENTOR. H AROLD A, CARLSO N M J uEQ ATTORNEY.
Patented Mar. 18. 1941 PATENT OFFICE ACCEIERATING PUMP Application May 6, 1939. Serial No. 272,124
' 40mins. (01.261-34) invention relates to internal combustion engine carburetors and more particularly to accelerating devices to be used in connection therewith.
Auxiliary fuel is injected into the air stream in present day carburetors during engine acceleration when sufliclent fuel from aspirating nozzles cannot be obtained due to low air velocities through the carburetor or to low fuel levels in the aspirating nozzles due to pull back by interconnected idling fuel passages.
This auxiliary fuel is usually referredto as accelerating discharge and is most commonly provided by areciprocating plunger type accelcrating device interconnected by link mechanism to the carburetor throttle and adapted to discharge into the main air passage through the carburetor upon opening movements of the throttle. I V l it is obvious that in an automotive-type engine driving a vehicle, the air velocity through the carburetor which immediately ensues upon an opening movement of the throttle from a near closed or idling position with a. conunensurate engine speed, will. be low as compared to the immediate resulting velocity following a throttle opening movement from say, a. half open position with the normal corresponding engine speed.
Also it is evident in'the latter instance'that fuel will he flowing from the aspirating nozzle and that it possesses some momentum, whereas in the former instance an interval will be required to lift the fuel from some point below the point of discharge of the aspirating nozzle.
it has been found that in the operation of modern automotive internal combustion engines, this auxiliary fuel as supplied by an accelerating device is not required for throttle opening movements beyond a certain throttle open position. For economical reasons it is, therefore, advantageous to provide a. means of conserving the fuel during those throttle opening movements in which it is not required.
lit is an.- object of this inventionv to providean accelerating device of the above character in movements in which such auxiliary fuel is not required.
Other objects and advantages will appear upon referring to the following description and accompanying drawing in which Fig. 2 is a fragmentary view of the carburetor shown in Fig. 1 embodying a modification pf my invention.
Fig. 3 is also a fragmentary view of the carburetor shown in Fig. 1 embodying still another modification of my invention.
Referring to Fig. l, the referencenumeral i indicates a main carburetor body member having a mixing conduit 2 formed therein. A constant level fuel chamber 3 also formed in the main body member is provided and a constant level of fuel as indicated by thedot-da sh line the float 4 and throttle valve i l suitably attached for rotation with throttle shaft it as with screws l3.
Fuel for acceleration is supplied by an accelerating device comprising a cylindrical chamber l3 having a plunger it arranged for reciprocation therein. Motion is imparted to the plunger it upon movement of the throttle valve by means of the plunger shaft it, link, lever I'll which is pivoted at it, link l9 and lever 20 which is rigidly attached to the'throttle shaft l2.
Upon the intake or upward stroke of th plunger it, fuel flows into the chamber it from the constant level chamber 3 through the valve controlled passage it around the spring retained combination intake and by-pass valve it, fuel passages 23 and M and opening iii.
0n the downward or discharge stroke of the plunger it fuel is forced through opening it, passage 2% around gravity discharge valve ii through passages 2t and 2t and is discharged into the mixing conduit and the air stream through discharge nozzle 30 and orifice 51!.
In order to divert the fuel from the mixing conduit at a predetermined throttle position, I have provided the valve pin 3! which is guided in the casting t and held normally in the position shown by the spring 32. a
A lug 33 on lever l'l engages the pin St at some predetermined throttle position and any further opening movement of the throttle will cause pin 3| to be moved downwardly thereby forcing valve 22v downward and off its seat. The spring 3 which normally holds valve 22 on its seat is calibrated to permit the proper functioning of,valve 22 as an intake check valve...
Passages 35 and 36 in the plunger shaft H: are provided to relieve pressure in the chamber l3 which may result from vaporization of the fuel therein due to absorption of heat from surrounding engine parts and which would, if not relieved, cause untimely discharge of fuel into the mixing conduit. It will be understood that passage 36 in plunger shaft i5 is relatively small and the amount of fuel escaping therethrough during a discharge stroke is negligible.
A slot 31 in the wall I3 extending to a point below the level of fuel is provided to supply fuel to chamber l3 above the plunger l4 at all times thereby insuring a liquid seal for the plunger.
In the modification disclosed in Fig. 2 separate valves are provided for intake and by-pass control. Other associated elements similar to those shown in the device of Fig. l are indicated by similar numerals. The by-pass valve 38 in this arrangement is provided with a vertically extending stem 39 which is engaged by the plunger l4 at some predetermined throttle position after which any further throttle opening movement will force valve 33 downward causing the fuel to be by-passed back into the chamber 3, through openings 40 around valve 38 through passages 4|, 42 and 43.
It will be understood that the spring 44 which normally urges valve 38 upward in engagement engines and carburetors.
Referring to Fig. 2 on the upward or intake stroke fuel enters chamber I3 from the constant level bowl 3 through passages 43 and 42 around the gravity intake check 45 and through opening 46.
On the downward or discharge stroke fuel is discharged through opening 41, into the mixing conduit in a manner as previously described.
In the modification shown in Fig. 3 a by-pass valve 48 is provided and normally held in engagement with its seat in passage 49 through plunger 50 by the spring 5|.
A standard or pin 52 rigidly positioned at the bottom of chamber 13 forces valves 48 from its seat at a predetermined throttle position, permitting the fuel to be by-passed back into chamber 3 through passages 49 in plunger 50, passages 53 and 54 in plunger rod 55 and slot 31 in the wall of chamber l3.
Fuel enters chamber l3 on the intake stroke through opening 55 around gravity intake check 45 and passage 46 and is discharged into the mixing conduit through similar passages as shown in Figs. 1 and 2.
It will be understood that the orifice 51 in the discharge nozzle 30 is relatively small when compared with the net opening of the by-pass so that a relatively small amount of fuel is discharged therethrough after the by-pass valve is opened.
In operation fuel is supplied to the carburetor through inlet passages 53 and 53 and a substantially constant level of fuel is maintained in the chamber 3 by the float 4 and the needle 5,
Fuel for normal and high speed operation is supplied through orifice 50, passages BI, 62 and 83 and discharges into the mixing conduit at 64.
Fuel for idling or substantially closed throttle operation is supplied through orifice 65, passages 66, 61, restricting passage 63, passages 69, 10, ll, 12, I3, 14 and discharges near the edge of throttle plate l3 through port I5.
Upon throttle opening movements the accelerating device plunger is caused to move down in a manner described thereby discharging fuel for acceleration into the mixing conduit. As the throttle reaches a predetermined point the bypass valve is positively opened and any further discharge from the accelerating chamber is diverted.
On closing movements of the throttle, fuel is drawninto the accelerating chamber from the constant level chamber by the upward movement of the plunger. The detailed drawings and description are intended to be illustrative and not limiting, and the exclusive use of all modi; fications which come within the scope of the appended claims is contemplated.
I. In a carburetor, a mixture conduit, a constant level fuel bowl, a throttle in said conduit, aspirating fuel passage means connecting said fuel bowl with said conduit, an accelerating pump including a movable part and a working chamber, a passage connecting said working chamber with said fuel chamber and a more restricted discharge passage opening into said mixture conduit, a resiliently seated valve in said first-mentioned passage and an outwardly opening check valve in said discharge passage, a positively operating connection between said throttle and the movable part of said pump, and means actuated by movement of said movable part to positively unseat the valve in said connecting passage in coordination with discharging movement of said pump beyond a predetermined point whereby substantially the remainder of the pumped fuel is by-pas'sed through said connecting passage.
2. A carburetor as specified in claim 1 in which said connecting passage constitutes the sole inlet connection between the pump and said fuel chamber, the valve therein being responsive to charging movement of said pump for admitting fuel to the pump.
,3. A carburetor as specified in claim 1 including at least two passages connecting said working chamber with said fuel chamber, there being a pressure responsive valve in one of said passages operable upon charging movement of said pump movable part to admit fuel to said working chamber, said resiliently seated valve being located in a second one of said connecting passages.
4. A carburetor as specified in claim 1 in which said connecting passage extends through said pump movable part, there being additionally provided a fixed abutment projecting from a wall of said working chamber positioned to be engaged by said resiliently seated valve for unseating the same.
HAROLD A. CARLSON.