Safety limiter for engine speed

Claim 3

A method as set forth in claim 1 including the subsequent step of maintaining engine speed within a range below that necessary to engage the centrifugal clutch and above engine idle speed.

Claim 8

A method as set forth in claim 4 including the step of delaying limiting the engine speed for a time sufficient to allow normal engine deceleration to occur upon release of a throttle control by an operator.

Claim 9

A method as set forth in claim 5 including the step of reducing the length of the delay if the engine speed is accelerating when the speed is greater than the predetermined speed.

Claim 10

Apparatus for controlling the operating of a fuel powered engine comprising: means to indicate the engine speed during its operation, means to produce a control signal when the engine speed is indicated to be greater than a predetermined speed and only if the engine speed is not decreasing, and means to limit the engine speed to a predetermined speed in response to said control signal without stopping the engine operation.

Claim 11

Apparatus for controlling the operating of a fuel powered engine comprising: means to indicate the engine speed during its operation, means to produce a control signal when the engine speed is indicated to be greater than a predetermined speed and only if the engine speed is not decreasing, and means to limit the engine speed to a predetermined speed in response to said control signal without stopping the engine operation.

Claim 12

Apparatus as set forth in claim 7 including means to delay limiting the engine speed following production of said control signal.

Claim 13

Apparatus as set forth in claim 8 wherein the means to delay includes means to vary the length of the delay with engine acceleration.

Claim 14

A circuit for controlling the operating speed of an internal combustion engine having an electrical ignition, an operator-actuated throttle control, and that drives a load through a centrifugal clutch, the circuit comprising: a switch for sensing operator force upon the throttle control, first means to sense during engine operation whether or not the engine decelerates upon removal of actuating force from the throttle control, and second means operative only if the engine has not decelerated to interrupt the ignition until the engine speed is below that necessary to engage the centrifugal clutch.

Claim 15

A circuit for controlling the operating speed of an internal combustion engine having an electrical ignition, an operator-actuated throttle control, and that drives a load through a centrifugal clutch, the circuit comprising: a switch for sensing operator force upon the throttle control, first means to sense during engine operation whether or not the engine decelerates upon removal of actuating force from the throttle control, and second means operative only if the engine has not decelerated to interrupt the ignition until the engine speed is below that necessary to engage the centrifugal clutch.

Claim 16

A circuit for controlling the operating speed of an internal combustion engine having an electrical ignition system, the circuit comprising: first means to sense the engine speed, and second means responsive to the first means to interrupt the ignition if (a) the engine speed is above a predetermined speed, (b) operator force on an actuator for a fuel throttle of the engine has been removed, and (c) the engine speed has not decreased within a predetermined time after removal of operator force from the actuator.

Claim 17

A circuit for controlling the operating speed of an internal combustion engine having an electrical ignition system, the circuit comprising: first means to sense the engine speed, and second means responsive to the first means to interrupt the ignition if (a) the engine speed is above a predetermined speed, (b) operator force on an actuator for a fuel throttle of the engine has been removed, and (c) the engine speed has not decreased within a predetermined time after removal of operator force from the actuator.

Claim 22

A method as set forth in claim 13 wherein said predetermined value is changed between an upper and lower value and including the step of maintaining the ignition interrupted until either said switch is operated to raise said predetermined value or the signal reaches the lower predetermined value.

Claim 23

An electrical circuit for controlling the operating speed of an internal combustion engine having an electrical ignition system, said circuit comprising: first means to sense the engine speed, second means responsive to the first means to interrupt the ignition when the engine speed is greater than a predetermined speed and to end the ignition interruption when the engine speed reduces, whereby the engine remains running, and third means to delay operation of the second means for a time duration that is varied with engine speed increase.

Claim 24

An electrical circuit for controlling the operating speed of an internal combustion engine having an electrical ignition system, said circuit comprising: first means to sense the engine speed, second means responsive to the first means to interrupt the ignition when the engine speed is greater than a predetermined speed and to end the ignition interruption when the engine speed reduces, whereby the engine remains running, and third means to delay operation of the second means for a time duration that is varied with engine speed increase.

Claim 25

A circuit as set forth in claim 10 wherein said second means is inoperative to interrupt the ignition at an engine speed as low as engine idle speed.

Claim 26

A circuit for controlling the operating speed of an internal combustion engine having an electrical ignition system, the circuit comprising: means to produce an electrical signal indicative of engine speed, means to detect when said signal reaches a predetermined value, means to interrupt said ignition in response to said signal reaching said value and until the signal value reduces to below said predetermined value, means including a switch associated with a throttle control for said engine to change said predetermined value, means to prevent interruption of the ignition when said signal is at or above a said predetermined value if said value decreases within a predetermined time, means to produce second electrical signals in the form of pulses proportional in frequency to engine speed and of a duration that varies in proportion to engine acceleration, and means to change said predetermined time in response to a change in said duration.

Claim 27

A circuit for controlling the operating speed of an internal combustion engine having an electrical ignition system, the circuit comprising: means to produce an electrical signal indicative of engine speed, means to detect when said signal reaches a predetermined value, means to interrupt said ignition in response to said signal reaching said value and until the signal value reduces to below said predetermined value, means including a switch associated with a throttle control for said engine to change said predetermined value, means to prevent interruption of the ignition when said signal is at or above a said predetermined value if said value decreases within a predetermined time, means to produce second electrical signals in the form of pulses proportional in frequency to engine speed and of a duration that varies in proportion to engine acceleration, and means to change said predetermined time in response to a change in said duration.

Claim 28

A circuit as set forth in claim 17 including means to maintain the ignition interrupted until either said switch is operated to raise said predetermined value or the signal reaches the predetermined value.

Claim 29

In a system for controlling the speed of an engine, a control circuit for connection among an alternator driven by the engine, an engine ignition circuit, and a switch sensitive to the position of a throttle actuator for the engine, said circuit comprising: a power supply with an input and an output, the input coupled to the alternator and the output forming a power source, pulse conditioning means including first means to compare two inputs, one from the power supply output and the other from the alternator, and to produce output pulses of a frequency proportional to engine speed, means to convert an input pulse frequency to a voltage the level of which is proportional to the frequency and including second means to compare two inputs, one from said pulse conditioning means and the other from its own output through a feedback circuit to produce a sawtooth voltage waveform, means to monitor the voltage from said second means, including third means to compare two inputs, one from said second means and the other from both said second means and a time delay circuit, to produce output pulses when said engine is running at a constant speed or accelerating, but not when decelerating, means for detecting the voltage level of the output from the frequency-to-voltage converting means, said means including fourth means to compare two inputs, one from the power supply and the other from the frequency-to-voltage converting means to produce an output when the voltage output of the frequency-to-voltage converting means reaches a predetermined level, and including means to change the level of the said other input through operation of said switch, thereby changing the output required from said frequency-to-voltage converter to produce an output from the voltage level detecting means, circuit means connecting the output of the monitor means to the said other input to the frequency-to-voltage converter to short the said other input to ground when no output is produced by said third means, to prevent any output from said fourth means from being produced, means for interrupting said ignition in response to an output from said fourth means, said time delay circuit including means to delay transmission of the output from said fourth means to the ignition interrupting means and means to produce an output that is coupled to said one input of said third means, and feedback means to couple said output from the time delay circuit to the said one input of said third means.

Claim 30

In a system for controlling the speed of an engine, a control circuit for connection among an alternator driven by the engine, an engine ignition circuit, and a switch sensitive to the position of a throttle actuator for the engine, said circuit comprising: a power supply with an input and an output, the input coupled to the alternator and the output forming a power source, pulse conditioning means including first means to compare two inputs, one from the power supply output and the other from the alternator, and to produce output pulses of a frequency proportional to engine speed, means to convert an input pulse frequency to a voltage the level of which is proportional to the frequency and including second means to compare two inputs, one from said pulse conditioning means and the other from its own output through a feedback circuit to produce a sawtooth voltage waveform, means to monitor the voltage from said second means, including third means to compare two inputs, one from said second means and the other from both said second means and a time delay circuit, to produce output pulses when said engine is running at a constant speed or accelerating, but not when decelerating, means for detecting the voltage level of the output from the frequency-to-voltage converting means, said means including fourth means to compare two inputs, one from the power supply and the other from the frequency-to-voltage converting means to produce an output when the voltage output of the frequency-to-voltage converting means reaches a predetermined level, and including means to change the level of the said other input through operation of said switch, thereby changing the output required from said frequency-to-voltage converter to produce an output from the voltage level detecting means, circuit means connecting the output of the monitor means to the said other input to the frequency-to-voltage converter to short the said other input to ground when no output is produced by said third means, to prevent any output from said fourth means from being produced, means for interrupting said ignition in response to an output from said fourth means, said time delay circuit including means to delay transmission of the output from said fourth means to the ignition interrupting means and means to produce an output that is coupled to said one input of said third means, and feedback means to couple said output from the time delay circuit to the said one input of said third means.

Claim 33

A control circuit for controlling the speed of an engine, adapted for connection among an alternator driven by the engine, an engine ignition circuit, and a switch sensitive to the position of a throttle actuator for the engine, said circuit comprising: means to produce pulses of a frequency proportional to engine speed, means to convert the pulse frequency to a voltage the level of which is proportional to the frequency, means to monitor the voltage to produce output pulses when said engine is running at a constant speed or accelerating, but not when decelerating, means for detecting the voltage level of the output from the frequency-to-voltage converting means and to produce an output when the voltage reaches a predetermined level, means to change said level through operation of said switch, circuit means connecting the output of the monitor means to the frequency-to-voltage converting means to prevent any output from said converting means when there is no output from the monitor means, means for interrupting said ignition in response to an output from said frequency-to-voltage converting means, a time delay circuit including means to delay transmission of the output from said frequency-to-voltage converting means to the ignition interrupting means and means to produce an output that is coupled to said monitor means, and feedback means to couple said output from the time delay circuit to the said monitor means.

Claim 34

A control circuit for controlling the speed of an engine, adapted for connection among an alternator driven by the engine, an engine ignition circuit, and a switch sensitive to the position of a throttle actuator for the engine, said circuit comprising: means to produce pulses of a frequency proportional to engine speed, means to convert the pulse frequency to a voltage the level of which is proportional to the frequency, means to monitor the voltage to produce output pulses when said engine is running at a constant speed or accelerating, but not when decelerating, means for detecting the voltage level of the output from the frequency-to-voltage converting means and to produce an output when the voltage reaches a predetermined level, means to change said level through operation of said switch, circuit means connecting the output of the monitor means to the frequency-to-voltage converting means to prevent any output from said converting means when there is no output from the monitor means, means for interrupting said ignition in response to an output from said frequency-to-voltage converting means, a time delay circuit including means to delay transmission of the output from said frequency-to-voltage converting means to the ignition interrupting means and means to produce an output that is coupled to said monitor means, and feedback means to couple said output from the time delay circuit to the said monitor means.

Claim 35

A circuit for controlling the operating speed of an internal combustion engine having a throttle, an electrical ignition and an operator-actuated control for the engine throttle, and that drives a load through a centrifugal clutch that engages at a predetermined engine speed, said circuit comprising: a normally open switch that is closed in response to operator force applied to the throttle control, and means to limit engine speed to below that necessary to engage the centrifugal clutch in response to said switch being open and regardless of the condition of the throttle.

Claim 36

A circuit for controlling the operating speed of an internal combustion engine having a throttle, an electrical ignition and an operator-actuated control for the engine throttle, and that drives a load through a centrifugal clutch that engages at a predetermined engine speed, said circuit comprising: a normally open switch that is closed in response to operator force applied to the throttle control, and means to limit engine speed to below that necessary to engage the centrifugal clutch in response to said switch being open and regardless of the condition of the throttle.