Apparatus for controlling rotational speed of internal combustion engine

Claim 5

Apparatus for reducing increases in engine power by limiting a speed control signal for an internal combustion engine during braking conditions of a vehicle mounting the engine, comprising: (a) means for producing an engine speed control signal including: a measuring device for measuring the rotational speed of the engine; comparing means for producing a deviation signal representative of a deviation between the measured rotational speed and a predetermined desired value; controlling means for producing a control signal having a value determined as a function of the deviation signal produced by said comparing means; and feedback control means for controlling the rotational speed of the engine, having a regulating means for controlling an amount of intake air entering the engine, said regulating means connected to and responsive to said control signal generated by said controlling means; (b) means for detecting the existence of a braking condition, said means for detecting producing a braking condition detection signal; and (c) limiting means for limiting the value of the control signal to values less than a predetermined upper limit, said limiting means being connected to and responsive to said braking condition detection signal, thereby to restrain an increase in the amount of intake air during a braking condition, whereby increases in stopping distance for a running vehicle are reduced; (d) said means for detecting comprising: first means for detecting engagement of a driving gear in a transmission for the internal combustion engine, and producing a first signal indicative of such engagement; second means for detecting a substantially closed position of a throttle valve of said internal combustion engine and producing a second signal indicative of such a closed position; third means for detecting a rotational speed of the internal combustion engine within a predetermined range and producing a third signal indicative of such a condition of the rotational speed; fourth means for detecting a vehicle speed below a predetermined speed and producing a fourth signal indicative of such a condition of the vehicle speed; and fifth means for producing said braking condition detection signal responsive to a simultaneous presence of each of said first, second, third and fourth signals.

Claim 6

Apparatus for reducing increases in engine power by limiting a speed control signal for an internal combustion engine during braking conditions of a vehicle mounting the engine, comprising: (a) means for producing an engine speed control signal including: a measuring device for measuring the rotational speed of the engine; comparing means for producing a deviation signal representative of a deviation between the measured rotational speed and a predetermined desired value; controlling means for producing a control signal having a value determined as a function of the deviation signal produced by said comparing means; and feedback control means for controlling the rotational speed of the engine, having a regulating means for controlling an amount of intake air entering the engine, said regulating means connected to and responsive to said control signal generated by said controlling means; (b) means for detecting the existence of a braking condition, said means for detecting producing a braking condition detection signal; and (c) limiting means for limiting the value of the control signal to values less than a predetermined upper limit, said limiting means being connected to and responsive to said braking condition detection signal, thereby to restrain an increase in the amount of intake air during a braking condition, whereby increases in stopping distance for a running vehicle are reduced; (d) said means for detecting comprising: first means for detecting engagement of a driving gear in a transmission for the internal combustion engine, and producing a first signal indicative of such engagement; second means for detecting a substantially closed position of a throttle valve of said internal combustion engine and producing a second signal indicative of such a closed position; third means for detecting a rotational speed of the internal combustion engine within a predetermined range and producing a third signal indicative of such a condition of the rotational speed; fourth means for detecting a vehicle speed below a predetermined speed and producing a fourth signal indicative of such a condition of the vehicle speed; and fifth means for producing said braking condition detection signal responsive to a simultaneous presence of each of said first, second, third and fourth signals.

Claim 11

An apparatus as claimed in claim 1, wherein said limiting means comprises decreasing means for decreasing the value of the control signal exponentially when the value of the control signal is larger than the upper limit.

Claim 12

An apparatus as claimed in claim 1 or 6, wherein the control signal comprises a proportional portion due to a proportional control action and an integral portion due to an integral control action.

Claim 13

An apparatus as claimed in claim 7, wherein said limiting means comprises subtracting means for subtracting the integral portion from the control signal.

Claim 14

An apparatus as claimed in claim 1, wherein said detecting means comprises a neutral portion switch to detect the neutral position of the transmission, a throttle valve switch to detect the closed position of the throttle valve and a vehicle speed switch to detect a condition in which the vehicle speed is under the predetermined speed.

Claim 15

An apparatus as claimed in claim 1, wherein said limiting means is a microcomputer so programmed as to perform the operation of said limiting means.

Claim 16

An apparatus as claimed in claim 1, wherein the predetermined range of the rotational speed of the engine is 600-350 rpm.

Claim 17

An apparatus as claimed in claim 1, wherein the predetermined speed of the vehicle is 12 km/h.

Claim 18

An apparatus as claimed in claim 1, wherein the predetermined upper limit is a value of the control signal which affords the intake air amount corresponding to the rotational speed of 800-900 rpm.

Claim 19

An apparatus as recited in claim 3 wherein said limiting means comprise decreasing means for decreasing the value of the control signal exponentially when the value of the control signal is larger than the upper limit.

Claim 20

The method recited in claim 5 wherein the reducing step comprises the further steps of: (a) determining a difference between the value of the control signal and the upper limit therefor; (b) dividing the determined deviation by a predetermined quantity; (c) determining whether the resulting quotient is below a particular value; (i) setting the resulting quotient equal to the particular value if the result of the determining step is positive; and (ii) retaining the quotient otherwise; (d) subtracting the quotient obtained in the setting step from the value of the control signal; (e) providing the difference obtained in the subtracting step as a new value for the control signal; and (f) storing the new value for the control signal in the storage therefor.

Claim 21

The method recited in claim 15 wherein said providing step comprises the further steps of: (a) determining whether the difference obtained in said subtracting step exceeds the upper limit; (i) continuing with the providing step if the result of the foregoing determining step is positive; (ii) setting the difference equal to the upper limit if the result of the foregoing determining step is negative; (b) setting a portion of the difference obtained in the subtracting step due to an integral control action equal to zero; and (c) continuing with the providing step.