US3741188A

US3741188A - Carburetor idle system air bleed

Info

Publication number: US3741188A
Application number: US00204616A
Authority: US
Inventors: R Rickey
Original assignee: Ford Motor Co
Current assignee: Ford Motor Co
Priority date: 1971-12-03
Filing date: 1971-12-03
Publication date: 1973-06-26
Anticipated expiration: 1990-06-26
Also published as: GB1384655A; DE2258550A1; JPS4867627A; CA965668A

Abstract

The carburetor idle system air/fuel channel has an additional air bleed that is opened and closed by an electrically controlled valve that is initially opened upon engine shutdown to bleed the idle channel fuel signal, to terminate fuel flow, and subsequently closed in response to engine vacuum decay, to recondition the idle channel for normal operation.

Description

c I United States Patent 1191 1111 3,741,188 Rickey June 26, 1973 [54] CARBURETOR IDLE SYSTEM AIR BLEED I 2,817,325 12/1957 Meissner 123/198 DC 3,482,562 12/1969 Ranft 123/198 DC [751 Invent R118" Rickey, Dearbmn Mlch- 3,682,148 8/1972 Harrison et al 123/198 DB x 73 A I F d 2,943,615 7/1960 Kainz 123/198 DC x Sslgnee Motor Company Dearbom 3,354,877 11/1967 Zub et a1. 123/1310. 11 3,158,144 1l/1964 Wacker 123/198 DC [22] Filed: Dec. 3, 1971 21 A L N 204 616 Primary Examiner Al Lawrence Smith 1 pp 0 Attorney- Keith L. Zerschling and Robert E. Mc-

Collum [52] US. Cl. 123/198 DB, 123/D1G. 11, 123/119,

123/179 G [51] Int. Cl. F02m 19/12, F02m 1/14, FOZd 33/00 [57] ABSTRACT [58] Field of Search 123/010. 11,97 B, The carburetor idle system air/fuel channel has an 123 93 1 193 DB, 193 DC, 79 B6, 179 G, ditional air bleed that is opened and closed by an elec- 130 E trically controlled valve that is initially opened upon engine shutdown to bleed the idle channel fuel signal, [56] Refe n Ci d to terminate fuel flow, and subsequently closed in re- UNITED STATES PATENTS sponse to engine vacuum decay, to recondition the idle 3,577,966 5/1971 Collingwood 123/198 DC x channel for normal operat'on' 3 Claims, 1 Drawing Figure CARBURETOR IDLE SYSTEM AIR BLEED This invention relates, in general, to a carburetor for an internal combustion engine. More particularly, it relates to a carburetor constructed with apparatus to terminate the idle system fuel flow in response to engine shutdown conditions to prevent afterrunning or dieseling of the engine.

Carburetor constructions are known in which valving is inserted in the engine idle system air/fuel mixture channel in response to engine shutdown to block off the flow of an air/fuel mixture to the engine cylinders to thereby prevent engine dieseling or afterrun. Such devices, however, generally are not satisfactory because of the extremely close tolerances required to assure that no fuel will leak past the valve when it is closed, or that air will not leak into the idle channel around the valve when the valve is withdrawn and normal operation of the idle system is desired.

It is an object of the invention, therefore, to provide an engine anti-dieseling device that automatically bleeds air into the engine idle system in response to engine shutdown to destroy the idle system fuel vacuum signal and thereby terminate fuel flow.

It is another object of the invention to provide a carburetor constructed with an atmospheric air bleed that will admit air into a portion of the idle system channel upon engine shutdown to decay the idle system fuel vacuum signal so that flow of idle system fuel will be terminated, while subsequently automatically closing the air bleed port after a predetermined time delay to recondition the idle system channel for normal operation and conventional engine starting.

It is a still further object of the invention to provide a carburetor constructed with an idle air/fuel channel having an air port that is normally blocked by an electrically controlled valve operable in response to engine ignition shut off to open the air port and bleed the vacuum signal acting on the idle system fuel jet to thereby terminate idle system fuel flow; the valve control being de-energized after a time delay corresponding to the time required for decay of manifold vacuum after engine shutdown, to move the valve to close the air bleed port and permit operation of the idle system in a conventional manner for engine starting and running.

Other objects, features and advntages of the invention will become more apparent upon reference to the succeeding detailed description thereof, and to the drawings illustrating a preferred embodiment thereof, wherein the FIGURE illustrates schematically a cross sectional view of a portion of a carburetor embodying the invention.

The carburetor in this case is for the most part a conventional one of the downdraft type. It includes a valve body having a central bore constituting the usual induction passage 14. The upper end of passage 14 generally would be connected to an air cleaner assembly lel relationship to induction passage 14 to supply an idle speed air/fuel mixture to the engine when throttle valve 18 is in its closed position shown. The upper end of the idle channel has a branch 24 connected to the air horn or essentially atmospheric pressure section of the carburetor through an orifice or anti-siphon bleed 26. The adjacent portion of passage 22 contains an idle system fuel jet 28, the upstream end of which would be connected to the conventional fuel float bowl, not shown. The top of the fuel in the float bowl normally is at the pressure of the top or air horn section of the carburetor.

The lower portion of idle channel 22 contains the usual transfer port 34 adapted to be straddled by the edge of throttle plate 18 when in its closed position shown. Also provided is an air/fuel mixture discharge port 36, the area of which is controlled by an adjustable needle valve 38.

Other details of construction and operation of the carburetor per se are not given since they are known and believed to be unnecessary for an understanding of the invention. Suffice it to say, however, that in normal operation, when the engine is running, the vacuum sigso as to be opened to air essentially at atmospheric nal below the throttle valve will act on discharge port 36 and that area of transfer port 34 located below the edge of the closed throttle valve. This will create a pressure differential across the two

idle channel orifices

26 and 28, causing a flow of both fuel and air through the idle channel out into the induction passage to the engine cylinders. This same vacuum signal, however, is present for a short-lived but determinate period upon engine shutdown prior to the engine crankshaft ceasing rotation, to continue drawing an idle channel air/fuel mixture into the engine cylinders. So long as this occurs, the engine may diesel or afterrun.

Turning now to the invention, therefore, the idle channel 22 is provided with a branch passage 40 that is open to air at atmospheric pressure. The passage is adapted to be closed by a solenoid controlled valve that is responsive both to engine ignition shutoff and a change in manifold vacuum pressure.

More specifically, a hollow casing 42 is threadedly mounted in the carburetor valve body as shown. It is open at opposite ends to communicate with air at atmospheric pressure at end 44 and with the passage 40 at the opposite end 46. A valve member 48 is slidably mounted in shell 42 and aligned with passage 40 for movement to block or open the passage. In this case, the valve is formed as an integral part of the armature 50 of a solenoid 51 having a coil illustrated at 52. A spring 54 normally biases the valve to close passage port 40 when the solenoid is de-energized.

The solenoid 51 is part of an electrical circuit that includes a conventional vehicle battery 56, an engine onoff ignition switch 58, an engine intake manifold vacuum controlled switch 60, and a relay controlled switch 62.

The vacuum switch may be of a known type having a spring 64 biasing the valve to normally open the switch contacts 65 and break the circuit, and closed to complete the circuit by intake manifold vacuum. The vacuum is connected to switch 60 from a carburetor port 66 through a line 67.

The relay control switch 62 is closed by a spring 68 to complete the circuit, when the relay is de-energized, the switch being opened to break the circuit upon energization of the relay coil 70.

It will be noted that the ignition on-off switch 58 and the manifold vacuum control switch 60 are arranged in a parallel flow circuit relationship between the battery and the relay control switch 62, and that the latter switch is in a series arrangement with the solenoid 51.

In operation, with the engine off, no manifold vacuum will exist. Accordingly, vacuum switch 60 will be moved by spring 64 to unbridge the contacts 65 and break the circuit between battery 56 and relay switch 62. The latter switch will have been spring closed since coil 70 is de-energized by the open ignition switch 58. Therefore, solenoid 51 will be ole-energized and spring 54 will maintain air bleed valve 48 seated in the passage 40 to block the admission of additional air.

After the engine has been started, by closing of ignition switch 58, manifold vacuum will cause vacuum switch 60 to close and complete the circuit from the battery 56 to the relay control switch 62. However, this latter switch will be in an open position due to the energization of relay 60 by the completion of the circuit from battery 56'through closed ignition switch 58. Accordingly, no current flows to solenoid 51 and the air bleed valve 48 remains seated. The engine idle system air/fuel mixture flow, therefore, operates in a conventional manner, as previously described. The vacuum switch 60 and relay switch 62 will remain in the positions described for all operating conditions of the engine until such time as it is desired to shut down the engine.

Upon engine shutdown, the ignition switch 58 is opened to the position shown, which breaks the circuit between the battery and the relay control switch 62. This allows the latter switch to close and bridge thecircuit between the closed vacuum'switch 60 and solenoid At the moment of ignition shut off, the continuing rotation of the engine crankshaft as it is slowing down continues to maintain a manifold vacuum on switch 60 to maintain it closed. Accordingly, for a predetermined time interval after engine ignition shut off, solenoid 51 will remain energizedto open the air bleed valve 48 and admit atmospheric air pressure into idle channel 22. This will immediately decay the pressure differential across the fuel jet 28 to immediately terminate idle channel fuel flow and thereby positively terminate con tinued running of the engine due to lack of a combustible mixture.

After a few seconds, the engine manifold vacuum will have decayed to a point permitting the vacuum switch spring 64 to again open switch 60 and break the circuit between the battery 56 and solenoid 51. The air bleed valve 48 then is closed by spring 54 and the idle channel again is conditioned for a-conventional operation for restarting and running the engine.

From the above, it will be seen that the invention provides an engine anti-dieseling device that is simple inconstruction and operation and yet positively terminates idle channel fuel flow after engine ignition shut off to prevent continued running of the engine, while subsequently reconditioning the idle system for a normal operation. for engine starting and running.

While the invention has been shown and described in its preferred embodiment, it will be clear to those skilled in the arts to which it pertains that many changes and modifications may be made thereto without departing from the scope of the invention.

-l claim:

1. An engine anti-dieseling control comprising, in combination, an engine carburetor having an induction passage open to atmospheric pressure at one end and adapted to be connected to an engine intake manifold at the opposite end so as to be subject to engine vacuum varying in level from ambient atmospheric pressure at engine shutdown to a maximum subatmospheric pressure level during engine deceleration operating conditions, a throttle valve rotatably mounted across the passage and movable from a closed position to an engine idle speed position and beyond to a wide open throttle position, and return, for controlling flow through the passage, an idle fuel/air mixture channel connected to the induction passage below the closed position of the throttle valve so that the idle channel is subjected to manifold vacuum at all times to provide normal idle and off idle speed vacuum signals with corresponding mixture flow, an air bleed port in the idle channel, an electrically controlled valve movable to open and close the port, an electrical circuit including an electrical source and electrically actuated means connected to the valve, first means responsive to engine shutdown completing the circuit and energizing the electrically actuated means to move the valve to open the port and decay the idle system fuel vacuum signal to terminate idle system fuel flow to prevent engine dieseling, and second means responsive to engine shutdown subsequent to operation of the first means to break the circuit and de-energize the electrically actuated means to effect movement of the valve to close the port, the first means including a spring closed first switch in the circuit and a relay associated therewith energizable to open the switch and break the circuit, and an engine ignition on-off second switch in'a series circuit arrangement with the first switch between the source and switch and in a parallel circuit arrangement with the second means.

2. An engine anti-dieseling control comprising, in combination, an engine carburetor having an induction passage open to atmospheric pressure at one'end and adapted to be connected to an engine intake manifold at the opposite end so as to be subject to engine vacuum varying in level from ambient atmospheric pressure at engine shutdown to a maximum subatmospheric pressure level during engine deceleration operating conditions, a throttle valve rotatably mounted across the passage and movable from a closed position to an engine idle speed position and beyond to a wide open throttle position, and return, for controlling flow through the passage, an idle fuel/air mixture channel connected to the induction passage below the closed position of the throttle valve so that the idle channel is subjected to manifold vacuum at all times to provide normal idle and off idle speed vacuum signals with corresponding mixture flow, an air bleed port in the idle channel, an electrically controlled valve movable to open and close the port, an electrical circuit including an electrical source and electrically actuated means connected to the valve, first means responsive to engine shutdown completing the circuit and energizing the electrically actuated means to move the valve to open the port and decay the idle system fuel vacuum signal to terminate idle system fuel flow to prevent engine dieseling, and second means responsive to engine shutdown subsequent to operation of the first means to break the circuit and de-energize the electrically actuated means to effect movement of the valve to close the port, the second means comprising a spring opened, engine manifold vacuum closed switch in the circuit between the source and first switch.

3. An engine anti-dieseling control comprising, in combination, an engine carburetor having an induction passage open to atmospheric pressure at one end and adapted to be connected to an engine intake manifold at the opposite end so as to be subject to engine vacuum varying in level from ambient atmospheric pressure at engine shutdown to a maximum subatmospheric pressure level during engine deceleration operating conditions, a throttle valve rotatably mounted across the passage and movable from a closed position to an engine idle speed position and beyond to a wide open throttle position, and return, for controlling flow through the passage, an idle fuel/air mixture channel connected to the induction passage below the closed position of the throttle valve so that the idle channel is subjected to manifold vacuum at all times to provide normal idle and off idle speed vacuum signals with corresponding mixture flow, an air bleed port in the idle channel, an electrically controlled valve movable to open and close the port, an electrical circuit including an electrical source and electrically actuated means connected to the valve, first means responsive to engine shutdown completing the circuit and energizing the electrically actuated means to move the valve to open the port and decay the idle system fuel vacuum signal to terminate idle system fuel flow to prevent engine dieseling, and second means responsive to engine shutdown subsequent to operation of the first means to break the circuit and de-engergize the electrically actuated means to effect movement of the valve to close the port, the electrically actuated means comprising a solenoid having an armature movable in one direction when energized and connected to the valve, and spring means biasing the armature in a return direction, the first means comprising a relay controlled first switch in the circuit that is spring closed to complete the circuit and opened to interrupt the circuit by energization of the relay, an engine ignition on-off switch in the circuit between the source and relay interrupting the circuit to the relay upon engine shutdown, the second means comprising a second switch that is in a series circuit arrangement with the relay between the source and relay and in a parallel circuit arrangement with the ignition switch, the second switch being spring opened and moved to a closed position by engine intake manifold vacuum applied thereto during running operation of the engine, opening of the ignition switch upon shutdown of the engine effecting closing of the relay to complete the circuit and energizethe solenoid to open the air port, the subsequent decay in manifold vacuum effecting opening of the second switch to break the circuit and de-energize the solenoid and effect closing of the air port.

Claims

1. An engine anti-dieseling control comprising, in combination, an engine carburetor having an induction passage open to atmospheric pressure at one end and adapted to be connected to an engine intake manifold at the opposite end so as to be subject to engine vacuum varying in level from ambient atmospheric pressure at engine shutdown to a maximum subatmospheric pressure level during engine deceleration operating conditions, a throttle valve rotatably mounted across the passage and movable from a closed position to an engine idle speed position and beyond to a wide open throttle position, and return, for controlling flow through the passage, an idle fuel/air mixture channel connected to the inDuction passage below the closed position of the throttle valve so that the idle channel is subjected to manifold vacuum at all times to provide normal idle and off idle speed vacuum signals with corresponding mixture flow, an air bleed port in the idle channel, an electrically controlled valve movable to open and close the port, an electrical circuit including an electrical source and electrically actuated means connected to the valve, first means responsive to engine shutdown completing the circuit and energizing the electrically actuated means to move the valve to open the port and decay the idle system fuel vacuum signal to terminate idle system fuel flow to prevent engine dieseling, and second means responsive to engine shutdown subsequent to operation of the first means to break the circuit and de-energize the electrically actuated means to effect movement of the valve to close the port, the first means including a spring closed first switch in the circuit and a relay associated therewith energizable to open the switch and break the circuit, and an engine ignition on-off second switch in a series circuit arrangement with the first switch between the source and switch and in a parallel circuit arrangement with the second means.

2. An engine anti-dieseling control comprising, in combination, an engine carburetor having an induction passage open to atmospheric pressure at one end and adapted to be connected to an engine intake manifold at the opposite end so as to be subject to engine vacuum varying in level from ambient atmospheric pressure at engine shutdown to a maximum subatmospheric pressure level during engine deceleration operating conditions, a throttle valve rotatably mounted across the passage and movable from a closed position to an engine idle speed position and beyond to a wide open throttle position, and return, for controlling flow through the passage, an idle fuel/air mixture channel connected to the induction passage below the closed position of the throttle valve so that the idle channel is subjected to manifold vacuum at all times to provide normal idle and off idle speed vacuum signals with corresponding mixture flow, an air bleed port in the idle channel, an electrically controlled valve movable to open and close the port, an electrical circuit including an electrical source and electrically actuated means connected to the valve, first means responsive to engine shutdown completing the circuit and energizing the electrically actuated means to move the valve to open the port and decay the idle system fuel vacuum signal to terminate idle system fuel flow to prevent engine dieseling, and second means responsive to engine shutdown subsequent to operation of the first means to break the circuit and de-energize the electrically actuated means to effect movement of the valve to close the port, the second means comprising a spring opened, engine manifold vacuum closed switch in the circuit between the source and first switch.

3. An engine anti-dieseling control comprising, in combination, an engine carburetor having an induction passage open to atmospheric pressure at one end and adapted to be connected to an engine intake manifold at the opposite end so as to be subject to engine vacuum varying in level from ambient atmospheric pressure at engine shutdown to a maximum subatmospheric pressure level during engine deceleration operating conditions, a throttle valve rotatably mounted across the passage and movable from a closed position to an engine idle speed position and beyond to a wide open throttle position, and return, for controlling flow through the passage, an idle fuel/air mixture channel connected to the induction passage below the closed position of the throttle valve so that the idle channel is subjected to manifold vacuum at all times to provide normal idle and off idle speed vacuum signals with corresponding mixture flow, an air bleed port in the idle channel, an electrically controlled valve movable to open and close the port, an electrical circuit including an electrical source and electrically actuated means connected to the valve, first means responsive to engine shutdown completing the circuit and energizing the electrically actuated means to move the valve to open the port and decay the idle system fuel vacuum signal to terminate idle system fuel flow to prevent engine dieseling, and second means responsive to engine shutdown subsequent to operation of the first means to break the circuit and de-engergize the electrically actuated means to effect movement of the valve to close the port, the electrically actuated means comprising a solenoid having an armature movable in one direction when energized and connected to the valve, and spring means biasing the armature in a return direction, the first means comprising a relay controlled first switch in the circuit that is spring closed to complete the circuit and opened to interrupt the circuit by energization of the relay, an engine ignition on-off switch in the circuit between the source and relay interrupting the circuit to the relay upon engine shutdown, the second means comprising a second switch that is in a series circuit arrangement with the relay between the source and relay and in a parallel circuit arrangement with the ignition switch, the second switch being spring opened and moved to a closed position by engine intake manifold vacuum applied thereto during running operation of the engine, opening of the ignition switch upon shutdown of the engine effecting closing of the relay to complete the circuit and energize the solenoid to open the air port, the subsequent decay in manifold vacuum effecting opening of the second switch to break the circuit and de-energize the solenoid and effect closing of the air port.