System and method for preventing start pinion/gear ring engagement during selected engine start conditions

• US 6,354,257 B1
• Filed: 08/09/2000
• Issued: 03/12/2002
• Est. Priority Date: 08/09/2000
• Status: Expired due to Fees

• Current Assignee: International Truck Intellectual Property Co. LLC (Volkswagen AG)
• Original Assignee: International Truck and Engine Corporation
• Inventors: Barnhart, Brent A., Marshall, Brian P.
• Primary Examiner(s): Dolinar, Andrew M.
• Application Number:
  US09/635,813
• Time in Patent Office: 580 Days
• Field of Search: 123/179.3, 123/179.4, 123/179.25, 290/38.R, 290/37.A
• US Class Current: 123/179.3
• CPC Class Codes: F02N 11/0851 characterised by means for controlling the engagement or disengagement between engine and starter, e.g. meshing of pinion and engine gear
• CPC Class Codes: F02N 11/105 when the engine is already running F02N11/0848 takes precedence
• CPC Class Codes: F02N 15/06 the toothed gears being moved by axial displacement
• CPC Class Codes: F02N 2250/04 Reverse rotation of the engine

Abstract

The invention provides a cranking inhibition control system for an electric starter to an internal combustion engine. Engine rotational speed is developed from the signal produced by a cam shaft position sensor, which drives the logic of the system. Responsive to changes in engine rotation speed which result in engine speed falling below idle speed, the control logic generates a temporary cranking inhibit signal. Once engine speed falls low enough to clearly indicate cranking has ceased, a timer is triggered which resets the inhibit signal to permit cranking after a suitable delay.

Claims

1. A control system for an electric starter to an internal combustion engine, the control system comprising:

a starter switch;

an engine crank shaft ring gear;

a cranking motor;

a pinion rotatably driven by the cranking motor;

a pinion positioner for selectively engaging and disengaging the pinion and engine crank shaft ring gear;

a tachometer for generating an engine rotational speed signal; and

control logic responsive to the engine rotational speed signal for determining deceleration of the engine indicative of resetting the start switch to off and further responsive to deceleration of the engine for generating an engine crank inhibit signal of one of two states.

2. A control system as claimed in claim 1, wherein the control logic further comprises:

a delay line connected to the tachometer to receive the engine rotational speed signal and responsive thereto for producing a delayed engine rotational signal;

a summing element connected to receive the engine rotational speed signal and the delayed engine rotational speed signal to produce a difference signal;

a source of a difference threshold reference signal; and

a comparator taking the difference signal and the difference threshold reference signal as inputs and responsive thereto for generating a minimum speed change indication signal of one of two states, where a first state indicates a change in engine rotational velocity consistent with cessation of engine cranking and a second state indicating otherwise.

3. A control system as claimed in claim 2, wherein the control logic further comprises:

a source of an engine speed reference signal;

a comparator taking the engine speed reference signal and the engine speed signal as inputs to produce a minimum engine speed signal of one of two states, where a first state indicates that engine speed falls below a minimum threshold and a second state which indicates that engine speed exceeds a minimum threshold;

a logical AND gate taking the minimum speed signal and the minimum speed change indication signal as inputs to provide a cranking inhibit set signal.

4. A control system as claimed in claim 3, wherein the control logic further comprises time delay reset element.

5. A control system as claimed in claim 4, wherein the time delay reset element further comprises:

a source of an engine off reference signal;

a resettable clock;

a comparator taking the engine off reference signal and the engine rotational speed signal as inputs to apply a clock reset signal to the resettable clock in response to the engine rotational speed failing below the engine off reference signal;

a source of a time threshold level; and

a clock comparator taking the output of the resettable clock and the time threshold level as inputs and generating a reset signal in response to the output of the resettable clock exceeding the time threshold level.

6. A control system as claimed in claim 5, further comprising a flip flop element connected to the AND gate to take the cranking inhibit set signal as a set input and to the output of the clock comparator as a reset input and generating a cranking inhibit signal of one of two states, a first state indicating that cranking is inhibited and a second state indicating otherwise.

7. A control system as claimed in claim 6, further comprising:

a crank inhibit relay connected to the starter switch and to the control logic to receive the engine crank inhibit signal and generating an activation signal in one of two states; and

a solenoid start relay connected to the crank inhibit relay to receive the activation signal.

8. A control system as claimed in claim 7, wherein a first state of the engine crank inhibit signal prevents cranking of the internal combustion engine.

9. A control system as claimed in claim 7, wherein a second state of the engine crank inhibit signal allows cranking of the internal combustion engine.

10. An engine controller for generating a command signal for application to an engine cranking system, comprising:

a source of an engine rotational velocity signal;

a delay line connected to the source of the engine rotational velocity signal for generating a delayed engine rotational velocity signal;

a subtracting circuit connected to the source of the engine rotational velocity signal and the delay line to produce a rotational velocity change signal;

a source of an engine rotational velocity change threshold level;

a comparator taking the engine rotational velocity change threshold level and the rotational velocity change signal as inputs and generating a first indication signal;

a source of an engine rotational velocity threshold level;

a comparator taking the engine rotational velocity threshold level and the engine rotational velocity signal as inputs and producing a second indication signal; and

an AND gate taking the first and second indication signals as inputs for setting an engine rate change status signal to inhibit engine cranking when both the first and second indication signals assume a first of two states.

11. An engine controller as set forth in claim 10, further comprising:

a source of engine off rotational velocity level;

an engine velocity comparator connected to receive the engine rotational velocity signal and the engine off rotational velocity level and producing an engine off signal at a set level if the engine rotational velocity signal indicates a minimum engine speed;

a reset clock initialized in response to the output signal of the engine velocity comparator assuming the set level;

a source of time delay value;

a reset comparator connected to receive the reset clock output and the time delay value for generating a reset signal for resetting the engine rate change crank signal.

12. An engine controller as claimed in claim 11 further comprising:

a source of a drive line status signal;

a source of an engine mode signal;

a source of a run latch flag;

a programmed engine mode level;

a programmed time threshold;

a comparator taking the programmed engine mode level and the engine mode signal as inputs to generate a clock initiation signal in response the engine mode signal matching the programmed engine mode level;

a source of time threshold;

a clock connected to receive the clock initiation signal;

a comparator taking the output of the clock and the source of the time threshold for generating a command signal of one of two values; and

and AND gate taking the run latch flag, the drive line status, the command signal and the delta crank inhibit signal all as inputs to generate and engine crank enable status signal.

13. An engine controller as claimed in claim 11, further comprising a programmable enable element.