Engine RPM control system

Claim 2

In an internal combustion engine of the type including an ignition system comprising an ignition coil having primary and secondary windings, the primary winding being connected in circuit with a battery and a set of points and the secondary winding being connected in circuit with one or more spark plugs, the improvement comprising means for limiting the revolutions per minute of said engine, said means comprising: means operatively coupled to said ignition system for generating a gating pulse which starts a fixed time interval after opening of said points and has a time duration which is a function of the desired speed of said engine; gating means having a gating terminal and first and second main terminals, said gating terminal being operatively coupled to receive said gating pulse, said gating means permitting conduction between said main terminals during said gating pulse; and threshold switching means connected between one of said main terminals of said gating means and one side of said primary winding of said coil for preventing conduction between said main terminals unless the voltage across said threshold switching means and said main terminals exceeds a predetermined threshold voltage whereby said gating means shorts said primary winding during said gating pulse when the voltage thereacross exceeds said predetermined threshold voltage.

Claim 3

In an internal combustion engine according to claim 1, the improvement wherein the value of said predetermined threshold voltage exceeds the voltage of said battery.

Claim 4

In an internal combustion engine according to claim 1, the improvement wherein said threshold switching means comprises: a zener diode connected in series between said one of said main terminals of said gating means and the junction between said primary winding and one side of said points.

Claim 5

In an internal combustioN engine according to claim 3, the improvement wherein the other of said main terminals of said gating means is connected to the other side of said points.

Claim 6

In an internal combustion engine according to claim 3, the improvement wherein the breakdown voltage of said zener diode is greater than the voltage of said battery whereby no current flows through said gating means unless the voltage across said points exceeds said breakdown voltage.

Claim 7

In an internal combustion engine according to claim 1, the improvement wherein said gating pulse generating means is responsive to the opening of said points.

Claim 8

In an internal combustion engine according to claim 1, the improvement wherein said gating pulse generating means comprises: first means responsive to the opening of said points for generating a timing pulse having a duration equal to said fixed time interval; and second means operatively coupled to the output of said first means and operative upon the termination of said timing pulse for generating said gating pulse.

Claim 9

In an internal combustion engine according to claim 7, the improvement further comprising: means operatively coupled to the junction between said primary winding and said set of points for clipping and filtering the voltage thereat to produce a signal which starts upon opening of said points and terminates upon closing of said points, said signal being applied to said first means, said first means generating said timing pulse upon said start of said signal.

Claim 10

In an internal combustion engine according to claim 7, the improvement wherein said first means comprises a first monostable multivibrator and wherein said second means comprises a second monostable multivibrator.

Claim 11

In an internal combustion engine according to claim 7, the improvement wherein the time duration of said gating pulse is variable to adjust the desired speed of said engine.

Claim 12

In an internal combustion engine according to claim 1, the improvement wherein said gating means comprises: a triac.

Claim 13

In an internal combustion engine according to claim 1, the improvement wherein said gating means comprises: an SCR.

Claim 14

In an internal combustion engine of the type including an ignition system comprising an ignition coil having primary and secondary windings, the primary winding being connected in circuit with a battery and a set of points and the secondary winding being connected in circuit with one or more spark plugs, the improvement comprising means for limiting the revolutions per minute of said engine, said means comprising: means operatively coupled to the junction between said primary winding and one of the points of said set of points for generating a first pulse which starts when said points open and terminates when said points close; means operatively coupled to said first pulse generating means for generating a second pulse starting concurrently with said first pulse and having a fixed time duration; means operatively coupled to said second pulse generating means and operative upon termination of said second pulse for generating a third pulse having a time duration which is a function of the desired speed of said engine; gating means having a gating terminal and first and second main terminals, said gating terminal being operatively coupled to the output of said third pulse generating means, said gating means permitting conduction between said main terminals during said third pulse; means connected between one of said main terminals of said gating means and said junction for establishing a threshold voltage level between said primary winding and said one main terminal; and means for connecting the other of said main terminals to the other of said points of said set of points whereby conduction occurs between said main terminals during said third pulse when said voltage at said junction exceeds said threshold voltage level.

Claim 15

In an internal combustion engine of the type including an ignition system comprising an ignition coil having primary and secondary windings, the primary winding being connected in circuit with a battery and a set of points and the secondary winding being connected in circuit with one or more spark plugs, the improvement comprising means for limiting the revolutions per minute of said engine, said means comprising: means operatively coupled to the junction between said primary winding and one of the points of said set of points for generating a first pulse which starts when said points open and terminates when said points close; means operatively coupled to said first pulse generating means for generating a second pulse starting concurrently with said first pulse and having a fixed time duration; means operatively coupled to said second pulse generating means and operative upon termination of said second pulse for generating a third pulse having a time duration which is a function of the desired speed of said engine; gating means having a gating terminal and first and second main terminals, said gating terminal being operatively coupled to the output of said third pulse generating means, said gating means permitting conduction between said main terminals during said third pulse; means connected between one of said main terminals of said gating means and said junction for establishing a threshold voltage level between said primary winding and said one main terminal; and means for connecting the other of said main terminals to the other of said points of said set of points whereby conduction occurs between said main terminals during said third pulse when said voltage at said junction exceeds said threshold voltage level.

Claim 16

In an internal combustion engine according to claim 13, the improvemEnt wherein the value of said threshold voltage level exceeds the voltage of said battery and biases said gating means to prevent conduction between said main terminals until the voltage across said set of points exceeds said threshold voltage level.

Claim 17

In an internal combustion engine according to claim 13, the improvement wherein said means for establishing a threshold voltage level comprises: a zener diode connected in series between said one of said main terminals of said gating means and said junction.

Claim 18

In an internal combustion engine according to claim 15, the improvement wherein the breakdown voltage of said zener diode is greater than the voltage of said battery whereby no current flows through said gating means unless the voltage across said points exceeds said breakdown voltage.

Claim 19

In an internal combustion engine according to claim 13, the improvement wherein said first pulse generating means comprises a first monostable multivibrator and wherein said second pulse generating means comprises a second monostable multivibrator.

Claim 20

In an internal combustion engine according to claim 17, the improvement wherein the time duration of said third pulse is variable to adjust the desired speed of said engine.

Claim 21

In an internal combustion engine according to claim 13, the improvement wherein said gating means comprises: a triac.