Engine starting device

Abstract

An engine starting device which makes fuel injected in preparation for ignition performed in a cylinder of an engine after starting drive of a starter motor in a forward rotational direction so as to start the engine, and makes ignition performed in a suitable ignition position at the time of engine start while the starter motor is driven in a forward rotational direction, the engine starting device being comprised so as to continue driving the starter motor in a direction for starting the engine, even when a crankshaft stops before a piston in a cylinder of the engine reaches a top dead center of a compression stroke.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other objects and features of the present invention will be apparent from the detailed description of the preferred embodiments of the invention, which is described and illustrated with reference to the accompanying drawings, in which;

FIG. 1 is a structural diagram illustrating construction of hardware of an engine system to which a starting device according to the present invention is applied;

FIG. 2 is a block diagram illustrating electric construction of the system illustrated in FIG. 1;

FIG. 3 is a block diagram illustrating construction of an engine starting device according to the present invention;

FIG. 4 is a sectional view illustrating a principal part of the engine illustrated in FIG. 1;

FIGS. 5A to 5C are explanatory diagrams for describing a relationship between strokes of two cylinders of a parallel two-cylinder four-cycle engine, the change of a load torque following the change of a crank angle, and initial fuel injection performed when reverse drive is completed in the starting device according to the present invention;

FIGS. 6A to 6C are explanatory diagrams for describing the change of strokes of a single-cylinder four-cycle engine, the change of a load torque following the change of a crank angle, and initial fuel injection performed when reverse drive is completed in the starting device according to the present invention;

FIG. 7 is a graph illustrating an example of a relationship between the engine load torque and the crank angle;

FIG. 8 is a graph illustrating an example of a relationship between the output torque and the rotational speed of a starter motor;

FIG. 9 is a graph illustrating an aspect that the rotational speed of a crankshaft changes with the change of a crank angle at the time of starting an engine in an embodiment of the present invention;

FIGS. 10A to 10E are waveform charts illustrating schematically a waveform of an output pulse of a signal generator and waveforms of output signals of Hall sensors which are used in the embodiment of the present invention;

FIG. 11 is a flowchart illustrating algorithm of control mode switching processing which a microprocessor executes in the embodiment of the present invention;

FIG. 12 is a flowchart illustrating algorithm of starting time ignition control processing which the microprocessor executes in the embodiment of the present invention;

FIG. 13 is a time chart for describing an ignition operation in the case of making multiple ignition performed at the time of starting an engine in the embodiment of the present invention;

FIG. 14 is a drawing illustrating a relationship between strokes of two cylinders of a parallel two-cylinder four-cycle engine;

FIG. 15 is a graph illustrating change of a rotational speed at the time of starting the parallel two-cylinder four-cycle engine by using a starter motor, whose output torques are different, in relation to a crank angle;

FIG. 16 is a graph illustrating an example of a relationship between a friction torque and an engine temperature of the two-cycle engine; and

FIG. 17 is a graph illustrating an example of a relationship between an output torque and a rotational speed of the starter motor.

Claims

1. An engine starting device which starts an engine including at least one cylinder in which a piston is provided, a crankshaft connected to the piston in the cylinder, a fuel injection device which injects fuel in order to generate an air-fuel mixture supplied into the cylinder, an ignition device which ignites the air-fuel mixture compressed in the cylinder, and a starter motor which rotationally drives the crankshaft, comprising: starter forward rotational drive means for driving the starter motor in a forward rotational direction in order to start the engine;starting time fuel injection control means for causing the fuel injection device to inject fuel for generating an air-fuel mixture supplied into a cylinder of the engine in preparation for ignition performed in the cylinder of the engine after the starter forward rotational drive means starts drive of the starter motor; andstarting time ignition control means for causing ignition in a cylinder of the engine to be ignited during a crank angle position of the engine being in a section suitable for performing ignition at the time of start-up in the cylinder, while the starter forward rotational drive means drives the starter motor in the forward rotational direction,wherein the starter forward rotational drive means is comprised so as to continue driving the starter motor in the forward rotational direction until a start of the engine is verified even when the crankshaft stops before the piston in the cylinder of the engine reaches a top dead center of a compression stroke.

2. The engine starting device according to claim 1, wherein the starter motor is comprised so as to be able to drive the crankshaft in both of a forward rotational direction and a reverse rotational direction, and further comprises starter reverse rotational drive means for driving the starter motor in the reverse rotational direction in order to once reversely rotate the crankshaft when a start command for the engine is given; and wherein the starter forward rotational drive means is comprised so as to drive the starter motor in the forward rotational direction in order to forwardly rotate the crankshaft after driving of the starter motor by the starter reverse rotational drive means is completed.

3. The engine starting device according to claim 2, wherein the starter reverse rotational drive means is comprised so as to drive the starter motor in the reverse rotational direction when the start command for the engine is given, and to reversely rotate the crankshaft of the engine until the piston in a specific cylinder, which has been stopped near a bottom dead center of a compression stroke at a time of forward rotation since the engine has stopped, is positioned in a section corresponding to an intake stroke at the time of forward rotation of the engine, or is in a position passed through the section.

4. The engine starting device according to claim 2, wherein the fuel injection control means is comprised so as to perform initial fuel injection when driving of the starter motor by the starter reverse rotational drive means is ended.

5. An engine starting device which starts an engine including at least one cylinder in which a piston is provided, a crankshaft connected to the piston in the cylinder, a fuel injection device which injects fuel in order to generate an air-fuel mixture supplied into the cylinder, an ignition device which ignites the air-fuel mixture compressed in the cylinder, and a starter motor which can rotationally drive the crankshaft in a forward rotational direction and a reverse rotational direction, comprising: start reverse rotational drive mode switching means for switching a control mode to a start reverse rotational drive mode when a start command for the engine is given;starter reverse rotational drive means for driving the starter motor in the reverse rotational direction in order to reverse the crankshaft when the control mode is switched to the start reverse rotational drive mode by the start reverse rotational drive mode switching means;reverse rotational drive time determination means for determining whether an elapsed time after starting drive of the starter motor in the reverse rotational direction reaches a set time set at sufficient length of time when the piston in a specific cylinder, which has been stopped near a bottom dead center of a compression stroke at a time of forward rotation of the engine since the engine has stopped, arrives in a set position set within a section corresponding to an intake stroke at the time of forward rotation of the engine, or set in a position passed through the section;reverse rotating time crank angle position determination means for determining whether the piston in the specific cylinder arrives in the set position while the starter motor is driven in the reverse rotational direction;start forward rotational drive mode switching means for switching the control mode to a start forward rotational drive mode when the reverse rotational drive time determination means determines that the elapsed time reaches the set time, or when the reverse rotating time crank angle position determination means determines that the crank angle position arrives in the set position;starter forward rotational drive means for starting drive of the starter motor in the forward rotational direction when the control mode is switched to the start forward rotational drive mode;starting time ignition control means for causing ignition in a cylinder of the engine to be ignited during a crank angle position of the engine being in a section suitable for performing ignition at the time of start-up in the cylinder, while the starter forward rotational drive means drives the starter motor in the forward rotational direction;fuel injection control means for causing the fuel injection device to perform initial fuel injection for said specific cylinder when the reverse rotational drive time determination means determines that the elapsed time reaches the set time, or when the reverse rotating time crank angle position determination means determines that the crank angle position arrives in the set position, and causing the fuel injection device to perform fuel injection in a crank angle position which is suitable as a position for injecting fuel for generating an air-fuel mixture supplied in a cylinder in which ignition is performed thereafter;start completion determination means for determining whether a start of the engine is completed;starter drive stopping means for stopping drive of the starter motor when the start completion determination means determines that the start of the engine is completed; andnormal operation mode switching means for switching the control mode to a normal operation mode when the start completion determination means determines that the start of the engine is completed,wherein the starter forward rotational drive means is comprised so as to continue driving the starter motor in the forward rotational direction even when the crankshaft stops before the piston in the specific cylinder reaches a top dead center of a compression stroke.

6. The engine starting device according to claim 1, wherein the starting time ignition control means is comprised so as to make multiple ignition performed in a cylinder to be ignited, whenever it is detected that a crank angle position of the engine enters into the section suitable for performing ignition at the time of start-up in each cylinder of the engine.

7. The engine starting device according to claim 2, wherein the starting time ignition control means is comprised so as to make multiple ignition performed in a cylinder to be ignited, whenever it is detected that a crank angle position of the engine enters into the section suitable for performing ignition at the time of start-up in each cylinder of the engine.

8. The engine starting device according to claim 5, wherein the starting time ignition control means is comprised so as to make multiple ignition performed in a cylinder to be ignited, whenever it is detected that a crank angle position of the engine enters into the section suitable for performing ignition at the time of start-up in each cylinder of the engine.

9. The engine starting device according to claim 1, wherein the section suitable for performing ignition at the time of a start in each cylinder of the engine is a section in a fixed angular range which is behind a crank angle position corresponding to a top dead center position of a piston of each cylinder.

10. The engine starting device according to claim 2, wherein the section suitable for performing ignition at the time of a start in each cylinder of the engine is a section in a fixed angular range which is behind a crank angle position corresponding to a top dead center position of a piston of each cylinder.

11. The engine starting device according to claim 5, wherein the section suitable for performing ignition at the time of a start in each cylinder of the engine is a section in a fixed angular range which is behind a crank angle position corresponding to a top dead center position of a piston of each cylinder.

12. The engine starting device according to claim 1, wherein the starter motor comprises a magnet rotor, a stator having a multiphase armature coil, a Hall sensor for each phase which detects a pole of the magnet rotor in a detection position set to the armature coil for each phase of the stator, and outputs a rectangular wave detection signal, and is comprised so as to be driven as a brushless motor in starting the engine; and wherein the starting time ignition control means and the fuel injection control means are comprised so as to acquire crank angle information on the engine necessary for control from an output of the Hall sensor for each phase.

13. The engine starting device according to claim 2, wherein the starter motor comprises a magnet rotor, a stator having a multiphase armature coil, a Hall sensor for each phase which detects a pole of the magnet rotor in a detection position set to the armature coil for each phase of the stator, and outputs a rectangular wave detection signal, and is comprised so as to be driven as a brushless motor in starting the engine; and wherein the starting time ignition control means and the fuel injection control means are comprised so as to acquire crank angle information on the engine necessary for control from an output of the Hall sensor for each phase.

14. The engine starting device according to claim 5, wherein the starter motor comprises a magnet rotor, a stator having a multiphase armature coil, a Hall sensor for each phase which detects a pole of the magnet rotor in a detection position set to the armature coil for each phase of the stator, and outputs a rectangular wave detection signal, and is comprised so as to be driven as a brushless motor in starting the engine; and wherein the starting time ignition control means and the fuel injection control means are comprised so as to acquire crank angle information on the engine necessary for control from output of the Hall sensors for each phase.

15. The engine starting device according to claim 1, wherein the engine comprises a decompression hole, which makes the interior of each cylinder communicate the outside, in a cylinder head.

16. The engine starting device according to claim 2, wherein the engine comprises a decompression hole, which makes the interior of each cylinder communicate the outside, in a cylinder head.

17. The engine starting device according to claim 5, wherein the engine comprises a decompression hole, which makes the interior of each cylinder communicate the outside, in a cylinder head.

18. The engine starting device according to claim 15, wherein a decompression valve which opens and closes the decompression hole and is controllable is provided, and decompression valve control means is further provided, the decompression valve control means controlling the decompression valve so as to open the decompression valve in starting the engine, and to close the decompression valve after the start of the engine.

19. The engine starting device according to claim 16, wherein a decompression valve which opens and closes the decompression hole and is controllable is provided, and decompression valve control means is further provided, the decompression valve control means controlling the decompression valve so as to open the decompression valve in starting the engine, and to close the decompression valve after the start of the engine.

20. The engine starting device according to claim 17, wherein a decompression valve which opens and closes the decompression hole and is controllable is provided, and decompression valve control means is further provided, the decompression valve control means controlling the decompression valve so as to open the decompression valve in starting the engine, and to close the decompression valve after the start of the engine.