Engine control system

Claim 2

A control system (10) for an engine system which includes an engine (11) having a crankshaft (211), an operator-controlled throttle (22), a fuel pump (16) for supplying fuel to the engine, the fuel pump having a fuel control means (21) for controlling the amount of fuel delivered to the engine, a first engine control means (13) comprising a timing means for setting the engine timing advance, and a second engine control means (23) comprising settable fuel control limit means for limiting the maximum amount of fuel deliverable from the fuel pump to the engine, characterized in that the control system (10) comprises a first condition signal means (38, 32, 43) for monitoring a first condition of the engine in operation and for generating a first condition signal having a value dependent upon the magnitude of the first condition; a second condition signal means (37, 32, 43 or 26, 27, 28) for monitoring a second condition of the engine in operation and for generating a second condition signal having a value dependent upon the magnitude of the second condition; control means (30) for storing a plurality of engine control signal values, each corresponding to a desired setting of the first or second engine control means (13 or 23)for engine operation at a particular combi- , nation of the first and second engine conditions, and for issuing an engine control signal in accordance with the particular values of the first and second engine - condition signals generated by the first and second condition signal means; and means (18 or 24) for setting one of the engine control means in accordance with the value of the generated engine control signal.

Claim 3

A control system according to claim 1 wherein the first condition signal means (38, 32, 43) is arranged to sense the speed of the engine (11), the second condition signal means (37, 32, 43) is arranged to sense the setting of the fuel control means (21), and the engine control means which is set is the timing means (13).

Claim 4

A control system according to claim 1, wherein the first condition signal means (38, 32, 43) is arranged to sense the speed of the engine (ll), the second condition signal means (26, 27, 28) is arranged to sense the setting of the timing means (13), and the engine control means which is set is the fuel control limit means (23).

Claim 5

A control system (10) according to any of claims 1 to 3, further including a third condition signal means (37, 32, 43 or 26, 27, 28) for monitoring a third condition of the engine in operation and for generating a third condition signal having a value dependent upon the magnitude of the third condition, the control signal means (30) also storing a plurality of engine control signal values, each corresponding to a desired setting of the first or second engine control means (13 or 23) for engine operation at a particular combination of the first and third engine conditions, and for issuing a second-engine control signal in accordance with-the particular values of the first and third engine condition signals generated by the first and third condition signal means; and means (24 or 18) for setting the other of the engine control means in accordance with the value of the second engine control signal.

Claim 6

A control system (10) according to claim 4, when dependent on claim 2, wherein the third condition signal means (26, 27, 28) is arranged to sense the setting of the timing means (13), and the engine control means which is set in the fuel control limit means (23).

Claim 7

A control system (10) according to claim 4, when dependent on claim 3, wherein the third condition signal means (37, 82, 43) is arranged to sense the setting of the fuel control means (21), and the engine control means which is set is the timing means (13).

Claim 8

A control system (10) according to claim 2, wherein the timing means (13) comprises means for varying the timing of fuel injection to the engine relative to crankshaft rotation.

Claim 9

A control system according to claim 3 or claim 6, wherein the control signal means (30) includes fuel/air signal means (71) for storing a plurality of fuel/air signal values each corresponding to a desired fuel-air ratio for engine operation at a particular combination of engine speed and engine timing and for generating a fuel-air signal having the predetermined value corresponding to the particular values of the first and second or first and third condition signals generated by the first and second or first and third condition signal means, the control system further including means (40, 32, 45) for generating a manifold pressure condition signal having a value proportional to the manifold pressure of the engine; means (76, 77) for generating a fuel-delivery signal having a value proporational to the value of the generated fuel/air , signal divided by the value of the generated manifold pressure condition signal; and means (72) for setting the fuel control limit means (23) the means (72) having stored therein a plurality of fuel control limit position control signal values, each corresponding to a desired . setting of the fuel control limit (23) for engine operation at a particular combination of fuel delivery and engine speed and for generating a fuel control limit position signal having a predetermined value corresponding to the particular values of the first condition signal generated by the first condition signal means and the fuel-delivery signal generated by the setting means (72).

Claim 10

A control system according to any of claims 1 to 8, wherein the first and second condition signals are each in binary coded form with a plurality of most significant bits and a plurality of least significant bits, and wherein the control signal means (-30) includes a read-only memory having a plurality of control signal values in binary form memory mapped in a series of rows and columns, each control signal value having of the Z values; stepping means for increasing by a binary one the binary values of the most significant bits of each of one of the condition signals; means for selecting a first row of the memory map in accordance with the binary value of the most significant bits of the one condition signal and for selecting a second row of the memory map in accordance with the increased value of the most significant bits of the one condition signal; means for selecting a first column of the memory map in accordance with the binary value of the most significant bits of another condition signal and for selecting a second column of the memory map in accordance with the increased value of the most significant bits of that other condition signal; means for storing outside of the' memory the value (Z 1 ) of the control signal from the first row and first column of the memory map, the value (Z 2 ) of the control signal from the second row and first column of the memory map, the value (2 3 ) of the control signal from the first row and second column of the memory map, and the value (Z 4 ) of the control signal from the second row and second colymn of the memory map; means for obtaining an interpolated binary binary value Z a equal to Z 1 plus the difference between Z 2 and Z 1 which is proportional to the binary value of the least significant bits of the one condition signal; means for obtaining an interpolated binary value Z b equal to Z 3 plus the difference between 2 4 and Z 3 which is proportional to the binary value of the least significant bits of the one condition signal; and means for obtaining a final interpolated control signal having a binary value Z 0 equal to Z a plus the difference between Z b and Z a which is proportional to the binary value of the least significant bits of the other condition signal.

Claim 11

A control system according to any of claims 1 to 9, wherein the first condition signal means (38, 32, 43) includes clock means (265) for generating a series of fixed frequency clock pulses; rotation responsive means (246) for generating a signal each successive time that the engine has rotated through 360/N degrees, N being an integer; counting means (269) for obtaining a count of the number of clock pulses occurring during a time interval beginning and ending with successive signals of the rotation responsive means (246), the counting means (269) having the function of obtaining a new such count each successive time that the engine has rotated through 360 M/N degrees, M being an integer; means (271) for generating a speed-indicating signal inversely proportional to each count of the counting means (269) each time that the engine has-rotated through 360 M/N degrees; and averaging means (272, 273) for generating the first condition signal each time that the engine has rotated through 360 M/N degrees, the first condition signal being equal to the sum of the number of successive speed-indicating signals obtained during two complete revolutions of the engine divided by the number of successive speed-indicating signals.

Claim 12

A control system according to claim 10, wherein the first condition signal means (38, 32, 43) further includes a second rotation responsive means (256) for generating a signal each successive time that the engine has rotated through 360/N degrees, and wherein the counting means (269) obtains the count of the number of clock pulses occuring during a time interval beginning and ending with successive pulses of the first mentioned rotation responsive means (246) in response to separately counting the number of clock pulses occurring in the interval beginning with a signal from the first mentioned rotation responsive means (246) and ending with the next occurring signal and counting the number of clock pulses occuring in the time interval beginning with the last mentioned signal from the second rotation responsive means (256) and ending with the next occurring signal of the first mentioned rotation responsive means (246).

Claim 13

A control system according to any of claims 1 to 9, wherein one of the condition signal means includes at least one first sensible member (212) rotatable at a speed proportional to the speed of the engine crankshaft (211); a first signal generating means (248) for generating a plurality of first signals on rotation of the first sensible member; at least one second sensible member (252) rotatable at a speed proportional to the speed of the fuel pump drive shaft; a second signal generating means (254) for generating a plurality of second signals on rotation of the second sensible member; clock means (265) for generating a series of fixed frequency clock pulses; counting means (269, 277) for:- a) obtaining a first count of the number of clock pulses occuring during the time interval (T l ) beginning and ending with consecutive signals from one of the first and second signal generators (248,254), b) Obtaining a second count of the number of clock pulses occurring in the time interval (T 2 ) beginning with a signal from one of the first and second signal generators and ending with a successive-signal from the other of the first and second signal enerators (248,254);and angle-indicating means for generating the condition signal of one of the condition signal means, the condition signal being proportional to the ratio of the first and second counts of the counting means.

Claim 14

A control system according to claim 12, wherein the one condition signal means is arranged such that N number of each of the first and second signals are generated by the first and second generator means (248, 254) during one full revolution of the crankshaft (211), N being an integer, wherein the counting means (269, 277) obtains N/M number of successive first and second counts during one full revolution, M being an integer, wherein the angle-indicating means generates N/M number of successive angle-indicating signals during one full revolution; and further including averaging means (272, 273) for generating the one condition signal each time that the engine has rotated through 360 M/N degrees, the one condition signal being equal to the sum of the number of successive angle-indicating signals obtained during two complete engine revolutions divided by the number of successive signals.

Claim 15

A control system according to claim 13, wherein in which TIM = the angle indicating signal, T l = the first count of the counting means T 2 = the second count of the counting means K T = a constant, and the angle-indicating means a) generating an initial reference angle-indicating signal TIM (o); b) generating a subsequent angle-indicating signal TIM (t), c) generating a corrected angle-indicating signal TIM (T) wherein when TIM (t) ≥ TIM (o), and , when TIM (t) < TIM (o).

Claim 16

A control system according to claim 12, wherein the other condition signal means includes means for generating the condition signal of the other condition signal means with the condition signal being inversely proportional to the first count of the counting means.

Claim 17

A control system according to any of claims 1 to 15, wherein the control signal means (30) includes first means for generating a first set of timing control signals each having a predetermined value corresponding to a desired engine timing for a first mode of engine operation and for a particular combination of engine speed and fuel control means positions, and second means for generating a second set of timing control signals each having a predetermined value corresponding to a desired engine timing for a second mode of engine operation and for a particular combination of actual engine speed and fuel control means position; and selector means (65) for selecting the first set of timing control signals to be used in controlling the timing means (13) when the engine is in said first mode of operation and for selecting the second set of timing control signals to be used in controlling the timing means (13) when said engine is in the second mode of operation.

Claim 18

A control system according to claim 16, wherein the first mode of engine operation is steady state urban operation and the second mode of engine operation is steady state highway operation and wherein the control system includes means (143) for generating an engine-speed-change signal in response to a change in engine speed; means (36) for generating a throttle-position signal in response to a depression or release of-the throttle; and wherein the selector means (65) includes means for obtaining a count of the number of times in a predetermined length of time that an engine-speed-change signal and a throttle-position signal are concurrently generated, and means for selecting the first set of timing control signals of the first means when the count is above a predetermined number and for selecting the second set of timing control signals of the second means when the count is below the predetermined number.

Claim 19

A control system according to claim 17, wherein the control system includes means (31) for sensing the temperature of the engine; and wherein the selector means (65) includes means for selecting the first set of timing control signals of the first means when the temperature of the engine is below a predetermined value and for selecting the second set of timing control signals of the second means when the temperature is above the predetermined value.

Claim 20

A control system according to claim 16 or claim 17, wherein the,control signal means (30) includes third means for generating a third set of timing control signals corresponding to a desired engine timing for a third mode of engine operation and for a particular combination of actual engine speed and fuel control means position; means (31) for sensing the temperature of the engine; and selector means for selecting the third set of timing control signals to be used in controlling'the timing means where the temperature of the engine is below a predetermined value and for selecting the first set or the second set of timing control signals to be used in controlling the timing means in accordance with whether the engine is in its first or second mode of operation and the temperature of the engine is above the predetermined value.

Claim 21

A control system according to claim 16, wherein the control signal means (30) includes first means for generating a first set of timing control signals each having a predetermined valm corresponding to a desired engine timing for a first mode of engine operation and for a predetermined combination of actual engine speed and fuel control means position, and second means .for generating a second set of timing control signals each having a predetermined value corresponding to a desired engine timing for a second mode of engine operation and for a particular combination of actual engine speed and fuel control means position; the control means also generating a third set of-timing control signals each having a predetermined value corresponding to a desired engine timing for a particular engine speed during acceleration and deceleration; means (36) for generating a throttle-position signal in response to depression or release of the throttle; and the selector means (65) selecting the third set of timing advance control signals for controlling the timing means when the throttle-position signal is present and for selecting one of the first and second sets of timing advance control signals of the first and second means for controlling the timing means when the throttle position signal is not present.