High rotational speed optimized engine starter having clutch connection to engine

• US 6,768,215 B2
• Filed: 08/02/2002
• Issued: 07/27/2004
• Est. Priority Date: 09/13/2001
• Status: Active Grant

• Current Assignee: DENSO Corporation
• Original Assignee: DENSO Corporation
• Inventors: Kato, Akira, Tani, Keisuke, Masaki, Kazuo, Kamiya, Masaru, Souki, Takahiro
• Primary Examiner(s): Tamai, Karl
• Assistant Examiner(s): Cuevas, Pedro J.
• Application Number:
  US10/209,909
• Publication Number:
  US 20030048014A1
• Time in Patent Office: 725 Days
• Field of Search: 290/7-10, 290/38.R, 290/40.C, 290/40.R, 290/46, 290/51, 310/78, 310/114
• US Class Current: 290/10
• CPC Class Codes: F02N 11/0844 with means for restarting the engine directly after an engine stop request, e.g. caused by change of driver mind
• CPC Class Codes: F02N 15/006 Assembling or mounting of starting devices
• CPC Class Codes: F02N 15/023 of the overrunning type
• CPC Class Codes: F02N 15/026 of the centrifugal type
• CPC Class Codes: Y02T 10/40 Engine management systems

Abstract

In an engine starter of the present invention, a driving shaft to output a rotating force and a crankshaft of an engine are linked continuously. The engine starter comprises a one-way clutch to prevent an overrun of an armature after the engine starts. In the one-way clutch, a connecting rotation number in which an inner ring and an outer ring change from a disconnected state to a connected state in a decreasing process of engine revolutions is set above a lower limit of the engine revolutions above which the engine under suspension of the fuel supply is able to get restarted by itself by resuming of fuel supply. Therefore, the engine is always able to get restarted quickly even in a low-rotation range.

Claims

1. An engine starter for starting an engine, the engine starter being mounted on a vehicle that has a system to suspend fuel supply to the engine automatically when predetermined conditions to turn off the engine are met, the engine starter comprising:

an electric motor to generate a rotating force to start the engine; and

a power transmission structure to transmit rotation of the motor to a crankshaft of the engine through a clutch that comprises at least a driving member connected to an output shaft of the motor and a driven member linked with the crankshaft, wherein

the clutch is able to transmit torque from the driving member to the driven member by forming a connected state between the driving member and the driven member and is able to cut off transmission of torque from the driving member to the driven member by forming a disconnected state between the driving member

the clutch defines a connecting rotation number as an upper limit of a rotation number of the driven member below which the driving member and the driven member are able to change from the disconnected state to the connected state in a decreasing process of engine revolutions, and

the connecting rotation number is set above a value corresponding to a limit of the engine revolutions above which the engine under suspension of the fuel supply is able to get restarted by itself by resuming supply of fuel without being driven by the electric motor.

2. The engine starter as in claim 1, wherein:

the clutch is a one-way clutch that forms the connected state only when the clutch transmits torque from the driving member to the driven member, and forms the disconnected state between the driving member and the driven member to prevent torque transmission from the driven member to the driving member when the rotation number of the driven member surpasses that of the driving member.

3. The engine starter as in claim 2, wherein:

the one-way clutch comprises a torque transmission member that is disposed between a torque output surface of the driving member and a torque input surface of the driven member and transmits torque from the driving member to the driven member through frictional connection with the torque output surface and the torque input surface, and a biasing member that presses the torque transmission member to contact the torque output surface and biases the torque transmission member in a direction to achieve transmission of torque; and

the torque transmission member is brought to a non-contacting state with the torque output surface when the rotation number of the driven member surpasses the connecting rotation number set as a rotation number in which a centrifugal force that is caused by rotation of the driven member and acts on the torque transmission member is balanced with a biasing force of the biasing member that biases the torque transmission member.

4. The engine starter as in claim 2, wherein:

the one-way clutch has a hysteresis set between the connecting rotation number and a disconnecting rotation number in an increasing process of the engine revolutions, wherein the disconnecting rotation number is defined as a rotation number of the driven member at which the driving member and the driven member change from the connected state to the disconnected state.

5. The engine starter as in claim 2, wherein:

the one-way clutch has a plurality of torque transmission members; and

the one-way clutch is formed so that a state in which a certain number of the torque transmission members more than a predetermined number are contacting a torque output surface of the driving member when the driving member and the driven member change from the disconnected state to the connected state in the decreasing process of the engine revolutions is regarded as the connected state.

6. The engine starter as in claim 1, wherein:

the motor is supplied with electric current when the rotation number of the driven member falls below the connecting rotation number, in case the engine is to be restarted after predetermined conditions to turn off the engine are met in the decreasing process of the engine revolutions.

7. The engine starter as in claim 1, wherein:

the power transmission structure comprises a planetary gear type reduction device.

8. The engine starter as in claim 1, wherein:

the power transmission structure comprises a driving pulley connected to a driving shaft of the motor, a crank pulley connected to the crankshaft and a belt linking the driving pulley and the crank pulley.

9. The engine starter as in claim 1, wherein:

the power transmission structure comprises a chain linking the driving shaft and the crankshaft.

10. The engine starter as in claim 1, wherein:

the power transmission structure comprises a timing belt linking the driving shaft and the crankshaft.

11. The engine starter as in claim 1, wherein:

the power transmission structure comprises a gear connected to the driving shaft.

12. The engine starter as in claim 2, wherein:

the one-way clutch comprises an inner ring, an outer ring facing the inner ring radially, sprags disposed between the inner ring and the outer ring, a retainer that holds the sprags so that the sprags are able to move in predetermined areas, and a garter spring that presses the sprags to contact a torque output surface of the inner ring and biases sprags in directions to achieve transmission of torque.

13. The engine starter as in claim 2, wherein:

the one-way clutch is a roller-type clutch.

14. The engine starter as in claim 2, wherein:

the one-way clutch has a plurality of torque transmission members; and

the one-way clutch is formed so that a state in which all of the torque transmission members are contacting a torque output surface of the driving member when the driving member and the driven member change from the disconnected state to the connected state in the decreasing process of the engine revolutions is regarded as the connected state.

15. The engine starter as in claim 8, wherein:

the driving pulley connected to the driving shaft is further linked with a pulley of accessories of the engine through the belt so that the motor is used to drive the accessories while the engine is not operated.

16. The engine starter as in claim 1, wherein:

the decreasing process of the engine revolutions is a process for stopping the engine by suspending the fuel supply to the engine.

17. A restarting method for restarting an engine with an engine starter during an engine stopping process, the engine starter having a clutch for transmitting rotating force of an electric motor to the engine in order to start the engine when the electric motor is connected to the engine through the clutch, the restarting method comprising the steps of:

disconnecting the electric motor from the engine by the clutch when the engine revolutions exceed a value corresponding to a disconnecting rotation number of the clutch during an engine starting process;

suspending fuel supply to start the engine stopping process under a condition that the engine is disconnected from the electric motor; and

connecting the electric motor to the engine by the clutch when the engine revolutions become equal to or lower than a value corresponding to a connecting rotation number of the clutch, which is higher than a rotation number of the clutch corresponding to a limit of the engine revolutions above which the engine under the suspension of the fuel supply is able to get restarted by itself by resuming of the fuel supply without being driven by the electric motor, so that the engine is restarted by the transmission of the rotating force of the electric motor and the resuming of the fuel supply to the engine.