US3800758A

US3800758A - Temperature actuated engine spark vacuum control system

Info

Publication number: US3800758A
Application number: US00312770A
Authority: US
Inventors: G Sutherland
Original assignee: Ford Motor Co
Current assignee: Ford Motor Co
Priority date: 1972-12-06
Filing date: 1972-12-06
Publication date: 1974-04-02
Anticipated expiration: 1991-04-02
Also published as: JPS5641824B2; CA985105A; AU458411B2; AU5937473A; GB1419160A; JPS49101742A; DE2359808A1; DE2359808C2

Abstract

A two position selector valve alternately connects EGR (exhaust gas recirculation) port vacuum or carburetor spark port vacuum to the engine distributor spark advance control as a function of outside ambient air temperature, to improve vehicle drivability while maintaining a constant emission level.

Description

United States Patent 1191 Sutherland Apr. 2, 1974 TEMPERATURE ACTUATED ENGINE 3,141,447 7/1964 .lernigan .1 123/119 A SPARK VACUUM CONTROL SYSTEM 3,738,108 6/]973 Goto l23/l 17 A Gilbert J. Sutherland, Trenton, Mich.

Assignee: Ford Motor Company, Dearbom,

Mich.

Filed: Dec. 6, 1972 Appl. No.: 312,770

Inventor:

us. 01. 123/117 A, 123/119 A 1m. (:1. F02p 5/04 Field of Search 123/119 A, 117 A References Cited UNITED STATES PATENTS 8/1972 Nakajima 123/119 A Primary Examiner-Laurence M. Goodridge Assistant ExaminerRonald B. Cox

[57] ABSTRACT A two position selector valve alternately connects EGR (exhaust gas recirculation) port vacuum or carburetor spark port vacuum to the engine distributor spark advance control as a function of outside ambient air temperature, to improve vehicle drivability while maintaining a constant emission level.

5 Claims, 2 Drawing Figures TEMPERATURE ACTUATED ENGINE SPARK VACUUM CONTROL SYSTEM This invention relates in general, to an internal combustion engine in which engine spark timing is controlled as a function of outside air temperature to control emissions while improving vehicle drivability.

The introduction of engine EGR (exhaust gas recirculation) to reduce NO, levels in most cases also results in a decrease in vehicle drive quality. The greater the proportion of EGR, the greater bleed of the manifold vacuum signal and a lesser induction of fuel/air mixture into the engine. This reduces fuel economy and results in poorer fuel distribution into the manifold runners; i.e., exhaust gases enter into the manifold to one side of the spacer and thus tend to create a difference in flow between the front and rear cylinders.

It is an object of this invention to improve the vehicle drive quality while holding a constant emission level.

In many cases, the vacuum signal for controlling the opening and closing of the EGR valve originates at a port in the carburetor induction passage located above the conventional spark port. The EGR port, therefore, sees the vacuum signal later and less often thanthe spark port, and the signal then is generally smaller.

It is another object of this invention to improve vehicle drivability without increasing emission levels by using both the EGR and spark ports as alternate vacuum sources for controlling engine distributor advance, the switching between the sources being controlled as a function of outside ambient air temperature 'to'provide more advance at lower temperatures for the same degree of carburetor throttle blade opening.

lt is also an object of the invention to provide an engine control device in which a vacuum operated servo controlling the movement of a force movable member is actuated at times by carburetor spark port vacuum so that the force movable member moves as a function of the degree of opening of the carburetor throttle valve, switching of the vacuum source from the carburetor spark port to a port higher in the induction passage effecting a change in the movement of the force movable member for the same degree of throttle valve opening, to thereby vary the movement of the force movable member in a desired manner.

Other objects, features and advantages of the invention will become more apparent upon reference to the succeeding detailed description thereof, and to the drawings illustrating the preferred embodiments thereof; wherein,

FIG. 1 is a schematic illustration of an internal combustion engine emission and spark timing control embodying the invention; and,

FIG. 2 is a cross-sectional view taken on a plane indicated by and viewed in the direction of the arrows 22 of FIG. 1.

FIG. 1 illustrates a portion of one-half of a fourbarrel carburetor of a known downdraft type. It has an air horn section 12, a main body portion 14, and a throttle body 16, joined by suitable means not shown. The carburetor has the usual air/fuel induction passages 18 open at their upper ends 20 to fresh air from the conventional which cleaner, not shown. The passages 18 have the usual fixed area venturies 22 cooperating with booster venturies 24 through whieh the main supply of fuel is induced, by means not shown.

Flow of air and fuel through induction passages l 8' is controlled by a pair of throttle valve plates 26. each fixed on a shaft 28 rotatably mounted in the side walls of the carburetor body.

The throttle body 16 is flanged as indicated for bolting to the top of the engine intake manifold 30, with a spacer element 32 located between. Manifold 30 has a number of vertical risers or bores 34 that are aligned for cooperation with the discharge end of the carburetor induction passages 18. The risers 34 extend at right angles at their lower ends 36 for passage of the mixture out of the plane of the figure to the intake valves of the engine.

The exhaust manifolding part of the engine cylinder head is indicated partially at 38, and includes an exhaust gas crossover passage 40. The gases pass from the exhaust manifold, not shown, on one side of the engine to the opposite side beneath the manifold trunks 36 to provide the usual hot spot beneath the carburetor to better vaporize the air/fuel mixture.

As best seen in FIG. 2, the spacer 32 is provided with a worm-like recess 42 that is connected directly to crossover passage 40 in FIG. 1 by a bore 44. Also connected to recess 42 is a passage 46 alternately blocked or connected to a central bore or passage 48 communicating with the risers 34 through a pair of ports 50. Mounted to one side of the spacer is a cup shaped boss 52 forming a chamber 54 through which passages 46 and 48 are interconnected.

As described above, it is necessary and desirable to provide some sort of control to prevent the recirculation of exhaust gases at undesirable times. For this purpose, passage 46 normally is closed by a valve 56 that is moved to an open position by a servo 58. The servo includes a hollow outer shell 64 containing an annular flexible diaphragm 66. The latter divides the interior into an air chamber '68 and a signal vacuum chamber 70. Chamber 68 is connected to atmospheric pressure through a vent 72, while chamber 70 is connected to a vacuum signal force through a line 74. Line 74 is connected to the carburetor induction passage, in a manner to be described later. The stem 75 of valve 56 is fixed to a pair of retainers 76 that are secured to diaphragm 66 and serve as a seat for a compression spring 77 normally biasing the valve to its closed position. The stem slidably and sealingly projects through a plate 78 closing chamber 54.

Returning to FIG. 1, a spark port 80 is tapped into the induction passage at a point just above or aligned with the idle position of throttle valve 26, to be traversed by the edge of the throttle valve during its opening part throttle movements. This will change the vacuum level in spark port 28 as a function of the rotative position of the throttle valve, the spark port reflecting essentially atmospheric pressure in the air inlet upon closure of the throttle valve. A second EGR port 82 is located above the spark port so that the latter port sees vacuum later than the spark port because it is uncovered later, for a purpose that will become clear later.

FIG. 1 also shows schematically an engine distributor 84 that includes a breaker plate 86 pivotably mounted at 88 on a stationary portion of the distributor and movable with respect to a cam 90. The latter has a number of peaks corresponding to the number of engine cylinders. Each peak cooperates with the follower 92 of a breaker point set 94 to make and break the spark connection in a known manner for each onesixth, in this case, rotation of cam 90. Pivotal movement of breaker plate 86 in a counterclockwise spark retard setting direction, or in a clockwise spark advance setting, is provided by an actuator 96 slidably extending from a vacuum servo 98.

Servo 98 may be of a conventional construction. It has a hollow housing 100 whose interior is divided into an atmospheric pressure chamber 102 and a vacuum chamber 104 by an annular flexible diaphragm 106. The diaphragm is fixedly secured to actuator 96, and is biased in a rightward retard direction by a compression spring 108. Chamber 102 has an atmospheric or ambient pressure vent, not shown, while chamber 104 is connected to a vacuum signal line 110. Line 110, in turn, is also connected to the carburetor induction passage in a manner that will become clear later.

During engine-off and other operating conditions to be described, atmospheric pressure exists on both sides of the diaphragm 106, permitting spring 108 to force the actuator 96 to the lowest spark timing advance or a retard setting position. Application of vacuum to chamber 104 moves diaphragm 106 and actuator 96 toward the left to an engine spark timing advance position, by degree, as a function of a change in vacuum level.

Turning now to the invention, the flow of spark port and EGR port vacuum to the EGR servo 58 and to the spark timing control servo 98 is controlled in FIG. 1 by a three port electrically controlled selector valve 114. Selector valve 114 includes a valve body having first and second inlet ports 1 l8 and 120 and one outlet port 122, connected respectively by

lines

124, 126 and 128 to spark port 80, EGR line 74, and distributor line 1 10. Valve 114 includes a two position slide valve 130 biased by a spring 132 to a lower position shown. In this position, it connects spark port vacuum in line 124 through an angled passage 134 to distributor line 128, while blocking EGR inlet 120. A solenoid 136, when energized, pushes the valve 130 upwardly to its second position. In this position, a U-shaped passage 138 connects the EGR port vacuum line 126 through

ports

120 and 122 and line 128 to distributor line 110, while blocking port 118.

Solenoid 136 is connected electrically to ground through a connection 140, and through a line 142 to a battery or other suitable power source 144. A switch 146 located in the line controls the energization of solenoid 136,

Switch 146 in this case is an ambient temperature sensitive thermostatic switch that is closed above, say 58F to complete the circuit, and opens when the temperature drops below that level. When closed, solenoid 136 is energized, and moves valve 130 upwardly. This will switch distributor advance signal in line 110 from spark port vacuum to EGR port vacuum, and condition the distributor for less advance for the same throttle blade setting. When the temperature drops below 58F., the circuit to solenoid 136 is broken, and the selector valve is in the position shown. Thus, spark timing advance occurs as a function of throttle valve movement and spark port vacuum level, which provides better performance and starting during cold weather operation.

It will be clear of course that other controls can be provided to control the switching function, within the scope of the invention. For example, an engine water temperature sensitive switch could be substituted for the switch 146.

I claim:

1. An engine spark timing and exhaust gas recirculation control comprising in combination, a carburetor induction passage having a throttle valve rotatably mounted therein and movable between positions opening and closing the induction passage, a spark port in the induction passage located above the closed position of the throttle valve, an exhaust gas recirculation (EGR) port located in the induction passage above and axially spaced from the spark port, an (EGR) servo having an (EGR) valve connected thereto and movable by vacuum applied to the servo to control flow of exhaust gases into the engine induction system, first conduit means connecting the (EGR) port to the (EGR) servo, a second engine spark timing control servo connected to a spark adjusting member of an engine distributor movable in opposite directions to advance or retard the spark, second conduit means connecting the spark port to the second servo, other conduit means connecting the first and second conduit means, and selector valve means in the other conduit means movable between positions alternately connecting spark port or (EGR) port vacuum to the second distributor servo to vary spark timing advance and retard for the same degree of throttle valve opening as a function of the position of the selector valve means, and means to move the selector valve means.

2. A control as in claim 1, including temperature sensitive means controlling the operation of the selector valve means to response to the attainment of a predetermined temperature level.

3. A control as in claim 1, including spring means biasing the (EGR) valve to a closed position, and spring means biasing the spark adjusting member towards a retard position.

4. A control as in claim 3, including solenoid means connected to the selector valve means and to a source of electrical energy, and other means to interrupt or break the circuit between the source and solenoid to control the switching of the second servo vacuum source from the spark port to the (EGR) port and vice versa.

5. A control as in claim 4, the other means comprising a temperature responsive on-off switch, and spring means biasing the selector valve means to a position connecting spark port vacuum to the second servo.