WO2017030815A1

WO2017030815A1 - Starter with disconnecting clutch

Info

Publication number: WO2017030815A1
Application number: PCT/US2016/045952
Authority: WO
Inventors: Michael W. CAMPBELL
Original assignee: BorgWarner Inc
Current assignee: BorgWarner Inc
Priority date: 2015-08-18
Filing date: 2016-08-08
Publication date: 2017-02-23
Anticipated expiration: 2018-02-18

Abstract

An apparatus for starting an internal combustion engine having a flywheel (102), includes a s a starter motor (112) having an output shaft (114) that rotates when the starter motor (112) is energized; an actuator (120) having a moving part (126) that moves from a first position to a second position when the actuator (120) is energized; a clutch (140) having a first clutch portion (142) and a second clutch portion (144), wherein the first clutch portion (142) rotates in unison with the output shaft (114) of the starter motor (112) and the moving part (126) of the actuator (120) is engaged with the first clutch portion (142) to engage and disengage the clutch (140); and a pinion gear (160) that is connected to the second clutch portion (144) and is engaged with the flywheel (102) for transferring rotation to the flywheel (102).

Description

STARTER WITH DISCONNECTING CLUTCH

BACKGROUND

[0001] In the field of internal combustion engines, it is well known to start the internal combustion engine using an electrically powered starter motor. In one common design, the electrically powered started motor is connected to a pinion gear that slides axially to engage with and disengage from a flywheel of the internal combustion engine. When the electrically powered starter motor is energized to start the internal combustion engine, an actuator moves the pinion gear into engagement with the flywheel and the electric motor rotates the pinion gear. The electric motor then cranks the engine by rotating the flywheel until the engine is operating under its own power. After the engine is operating under its own power, the electrically powered starter motor is energized and the actuator moves the pinion gear out of engagement with the flywheel.

[0002] Traditionally, the operator of a vehicle would start the engine of the vehicle at the beginning of a trip, drive to a destination, and then stop the engine of the vehicle at the end of the trip. In this example, the internal combustion engine remains running for the duration of the trip.

[0003] Vehicle shutoff systems have been implemented to increase fuel economy. A vehicle shutoff system is intended to reduce fuel consumption by stopping the internal combustion engine while the vehicle is stopped, such as when the vehicle is stopped at a traffic signal or is stopped in traffic. When the operator of the vehicle

subsequently tries to move the vehicle, the vehicle is restarted. Operation of vehicle shutoff systems is typically automatic, and can be controlled by a computing device, which is commonly referred to as a controller.

[0004] To promote use of vehicle shutoff systems by vehicle operators, some designs have attempted to make operation of the system unnoticeable by the operator. This can include, as examples, reducing the amount of noise and vibration when the engine shuts down and starts up, and reducing the amount of time that it takes to restart the engine.

[0005] The time needed to engage and disengage the pinion gear of an electrically powered starter motor increases the amount of time required to start the engine. Also, if the vehicle shutoff system needs to restart the engine shortly after stopping it, the flywheel may still be rotating, which prevents engagement of the pinion gear. For these and other reasons, electrically powered started motors have been developed that keep the pinion gear engaged with the flywheel at all times and thus do not include an actuator for moving the pinion gear into and out of engagement with the flywheel. However, continuously engaged flywheel designs are often associated with increased vibration levels, such as when the engine stops.

SUMMARY

[0006] One aspect of the disclosed embodiments is an apparatus for starting an internal combustion engine having a flywheel. The apparatus includes a flywheel, a starter motor having an output shaft that rotates when the starter motor is energized; an actuator having a moving part that moves from a first position to a second position when the actuator is energized; a clutch having a first clutch portion and a second clutch portion, wherein the first clutch portion rotates in unison with the output shaft of the starter motor and the moving part of the actuator is engaged with the first clutch portion to engage and disengage the clutch; and a pinion gear that is connected to the second clutch portion and is engaged with the flywheel for transferring rotation to the flywheel.

[0007] Another aspect of the disclosed embodiments is an apparatus for starting an internal combustion engine having a flywheel. The apparatus includes a starter motor having an output shaft that rotates when the starter motor is energized; an actuator having a solenoid that is operable to move a fork from a first position to a second position when the actuator is energized; a shaft assembly that is connected to the output shaft of the starter motor; a jaw clutch that is arranged on the shaft assembly, the jaw clutch having a first clutch portion and a second clutch portion, wherein the first clutch portion rotates in unison with the output shaft of the starter motor, the fork of the actuator is engaged with the first clutch portion to engage and disengage the jaw clutch, the first clutch portion is operable to transfer rotation to the second clutch portion when the clutch is engaged, and the first clutch portion is not operable to transfer rotation to the second clutch portion when the clutch is disengaged; and a pinion gear that is connected to the second clutch portion and is engaged with the flywheel for transferring rotation to the flywheel.

BRIEF DESCRIPTION OF THE DRAWINGS

[0008] The description herein makes reference to the accompanying drawings, wherein like referenced numerals refer to like parts throughout several views, and wherein:

[0009] FIG. 1 is a side view showing a starter and a flywheel of an internal combustion engine in which a starter disconnect clutch is in a disengaged position;

[0010] FIG. 2 is a side view showing the starter and the flywheel of the internal combustion engine in which the starter disconnect clutch is in the engaged position;

[0011] FIG. 3 is a cross-section view showing the starter disconnecting clutch; and

[0012] FIG. 4 is a cross-section view showing an alternative embodiment of the starter disconnecting clutch.

DETAILED DESCRIPTION

[0013] The disclosure herein is directed to a starter for an internal combustion engine in which a pinion gear of the starter is constantly engaged with the flywheel. The starter includes a disconnecting clutch that reduces vibrations that would otherwise be caused by a constantly engaged pinion gear, such as vibrations from torque reversals that can occur when the internal combustion engine stops.

[0014] FIG. 1 shows a starter assembly 100 for an internal combustion engine (not shown) including a starter 1 10 that is operably engaged with a flywheel 102 of the internal combustion engine.

[0015] The starter 1 10 includes a starter motor 1 12 that has an output shaft 1 14. The starter motor 1 12 is an electrical motor, as is well-known in the art. The output shaft 1 14 can be directly coupled to the starter motor 1 12, as shown in the illustrated example, or can be indirectly connected to the starter motor 1 12, such as by a gear train. The starter motor 1 12 has an energized state and a de-energized state. In the energized state of the starter motor, electrical power is supplied to the starter motor

1 12, which causes rotation of the output shaft 1 14. In the de-energized state of the starter motor 1 12, electrical power is not supplied to the starter motor 1 12, and therefore, the starter motor 1 12 does not cause rotation of the output shaft 1 14.

[0016] The starter 1 10 also includes an actuator 120. The actuator 120 is operable to connect and disconnect a torque transfer path between the starter motor 1 12 and the flywheel 102.

[0017] In the illustrated example, the actuator 120 includes a solenoid 122 having a plunger 124. The solenoid 122 can be conventional and causes movement of the plunger 124 in response to energization and de-energization of a coil (not shown) of the solenoid 122. In one implementation, the solenoid 122 can cause retraction of the plunger 124 in response to supply of electrical power to the coil of the solenoid 122 and can cause extension of the plunger 124 of the solenoid 122 in response to de- energization of the coil of the solenoid 122.

[0018] The actuator 120 also includes a moving part 126 that is used to connect and disconnect the torque transfer path between the starter motor 1 12 and the flywheel 102. In the illustrated example, the moving part 126 of the actuator 120 is a pivotal shift fork. It should be understood, however, that other types of structures could be used as the moving part 126 of the actuator 120. As an example, a translating shift fork could be used as the moving part 126 of the actuator 120. In addition, the moving part 126 could be a structure other than a shift fork.

[0019] In the illustrated example, the moving part 126 of the actuator 120 is connected to the plunger 124 of the solenoid 122 by a first pivot joint 128. The moving part 126 of the actuator 120 is also connected to a structure that does not move with respect to the starter motor 1 12 by a second pivot joint 130. For example, a backing plate 132 can be connected to the starter motor 1 12, and the moving part 126 can be connected to the backing plate 132 by the second pivot joint 130.

[0020] In order to connected and disconnect the torque transfer path between the starter motor 1 12 and the flywheel 102, the starter assembly 100 includes a clutch 140. The clutch 140 includes a first clutch portion 142 and a second clutch portion 144. The first clutch portion 142 is connected to the output shaft 1 14 of the starter motor 1 12 such that the first clutch portion 142 rotates in unison with the output shaft

1 14 of the starter motor 1 12. The second clutch portion 144 is connected to a pinion gear 160. The second clutch portion 144 can be connected to the pinion gear 160 such that it rotates in unison with the pinion gear 160. The pinion gear 160 is engaged with the flywheel 102. Engagement of the pinion gear 160 with the flywheel 102 is through gear teeth that are formed on each of the pinion gear 160 and the flywheel 102. The gear teeth can be, as examples, spur gear teeth or helical gear teeth.

[0021] The first clutch portion 142 and the second clutch portion 144 are disposed on a shaft assembly 200 that extends along a shaft axis. The shaft axis is the axis around which the pinion gear 160 rotates. The pinion gear 160 has a fixed axial position along the shaft assembly 200. The second clutch portion 144 can also have a fixed axial position along the shaft assembly 200. As will be explained further herein, the first clutch portion 142 can slide axially along the shaft assembly 200 between a first position (FIG. 1) in which the first clutch portion 142 is retracted from the second clutch portion 144 to define a space between the first clutch portion 142 and the second clutch portion 144 such that torque is not transferred between the first clutch portion 142 and the second clutch portion 144, and a second position in which the first clutch portion 142 is extended axially along the shaft assembly 200 into engagement with the second clutch portion 144 such that the first clutch portion 142 and the second clutch portion 144 are able to rotate in unison in response to rotation of the output shaft 114 by the starter motor 112.

[0022] Movement of the clutch 140 between the engaged position and the disengaged position is accomplished by engagement of the moving part 126 of the actuator 120 with the first clutch portion 142. In particular, the first clutch portion 142 can include an annular groove 146 that extends around the axis of the shaft assembly 200. An end portion 131 of the moving part 126 is disposed within the annular groove 146 of the first clutch portion 142. Thus, when the moving part 126 moves, such as by pivoting, in response to extension and retraction of the plunger 124 of the solenoid

122, movement of the moving part 126 causes axial motion of the first clutch portion 142 along the axis of the shaft assembly 200 between engagement and disengagement of the first clutch portion 142 with the second clutch portion 144. In some

implementations, the end portion 131 of the moving part 126 is a fork that extends around the first clutch portion 142 within the annular groove 146 to opposed sides of the first clutch portion 142. [0023] In some implementations, the clutch 140 is a jaw clutch. Other types of clutches can be utilized to establish and eliminate the torque transfer path between the starter motor 1 12 and the pinion gear 160.

[0024] In some implementations, the clutch 140 can have an overrunning configuration. In these implementations, such as in the illustrated example, the mating surfaces 148, 150 of the first clutch portion 142 and the second clutch portion 144, respectively, are configured to transfer torque in a first direction, but to not transfer torque in a second direction opposite the first direction. The first direction is the direction in which the starter motor 1 12 rotates in order to start the internal combustion engine. After the internal combustion engine starts, the clutch 140 may remain engaged momentarily. When this occurs, the rotational speed of the second clutch portion 144 will exceed the speed at which the first clutch portion 142 is rotated by the starter motor 1 12. In order to prevent the increased rotational speed from being transferred to the starter motor 1 12, the mating surfaces 148, 150 are configured to allow the second clutch portion 144 to slip with respect to the first clutch portion 142.

[0025] FIG. 3 shows the shaft assembly 200 according to one implementation. The shaft assembly 200 includes a one-piece shaft 210 that is coupled to the output shaft 1 14 of the starter motor 1 12 for rotation in unison with the output shaft 1 14. The first clutch portion 142 is coupled to the shaft 210 such that it rotates in unison with the shaft 210 but is able to slide axially with respect to the shaft 210. In the illustrated example, this connection is made using splines 212. The second clutch portion 144 and the pinion gear 160 are shown as parts of an integral unit but could be formed separately. In the illustrated example, the second clutch portion 144 and the pinion gear 160 are restrained from moving axially with respect to the shaft 210 by retainers

214, 216. The second clutch portion 144 and the pinion gear 160 are mounted to the shaft 210 for rotation relative to the shaft 210 and around the shaft axis, by structures such as bearings 218.

[0026] FIG. 4 shows a shaft assembly 300 according to an alternative

implementation, which can be utilized instead of the shaft assembly 200 in the starter assembly 100 of FIGS. 1-2. The shaft assembly 300 includes a first shaft portion 310 and a second shaft portion 320. The first shaft portion 310 is fixed to the output shaft 1 14 of the starter motor 1 12 for rotation in unison with the output shaft 1 14. The second shaft portion 320 is rotatable with respect to the first shaft portion 310 through a connection by elements such as bearings 302.

[0027] The first clutch portion 142 is connected to the first shaft portion 310 for rotation in unison with the first shaft portion 310 and for axial movement with respect to the first shaft portion 310. In the illustrated example, this connection is made using splines 312, which prevent rotation of the first clutch portion 142 relatively to the first shaft portion 310 while allowing sliding.

[0028] The connection between the first shaft portion 310 and the second shaft portion 320 is made in the area where the first clutch portion 142 engages the second clutch portion 144. Although this connection is shown in the illustrated example by a part of the second shaft portion 320 extending into a cavity in the first shaft portion 310, it should be understood that other configurations could be utilized.

[0029] The second clutch portion 144 and the pinion gear 160 are shown as being formed integrally with one another but could be formed separately. The second clutch portion 144 and pinion gear 160 are fixed to the second shaft portion 320 for rotation in unison with it and are fixed such that they are not able to slide axially with respect to the second shaft portion 320. The second clutch portion 144 and the pinion gear 160 can be formed separately from the second shaft portion 320 and fixed to it by any suitable method or structure or method. Alternatively, the second clutch portion 144 and the pinion gear 160 could be formed integrally with the second shaft portion 320.

[0030] In operation, the starter assembly 100 can be utilized to start the internal combustion engine by rotating the flywheel 102 of the internal combustion engine. Initially, the clutch 140 is disengaged. For example, the first clutch part 142 can be disposed in a first position in which it is axially spaced from and disengaged from the second clutch part 144. The actuator 120 is energized to move the moving part 126. The moving part 126 moves from a first position to a second position while engaging the first clutch portion 142. This causes movement of the first clutch part 142 axially along the shaft assembly 200 to its second position, in which the first clutch part 142 is in contact with the second clutch part 144, which places the clutch 140 in its engaged position. Upon energization of the starter motor 1 12, the starter motor 1 12 rotates the first clutch part 142, which in turn rotates the second clutch part 144. Rotational force delivered to the pinion gear 160 from the clutch 140, which causes rotation of the flywheel. If the speed of the flywheel surpasses the speed of the output shaft 114 of the starter motor 112 while the clutch 140 remains engaged, the second clutch part 144 is able to slip relative to the first clutch part 142. After the internal combustion engine has started, the actuator 120 and the starter motor 112 are de- energized.

[0031] While the disclosure has been made in connection with what is presently considered to be the most practical and preferred implementation, it should be understood that the disclosure is intended to cover various modifications and equivalent arrangements.

Claims

1. An apparatus for starting an internal combustion engine having a flywheel (102), comprising:

a starter motor (1 12) having an output shaft (1 14) that rotates when the starter motor (1 12) is energized;

an actuator (120) having a moving part (126) that moves from a first position to a second position when the actuator (120) is energized;

a clutch (140) having a first clutch portion (142) and a second clutch portion (144), wherein the first clutch portion (142) rotates in unison with the output shaft (1 14) of the starter motor (1 12) and the moving part (126) of the actuator (120) is engaged with the first clutch portion (142) to engage and disengage the clutch (140); and

a pinion gear (160) that is connected to the second clutch portion (144) and is engaged with the flywheel (102) for transferring rotation to the flywheel (102).

2. The apparatus of claim 1, wherein the first clutch portion (142) is operable to transfer rotation to the second clutch portion (144) when the clutch (140) is engaged, and the first clutch portion (142) is not operable to transfer rotation to the second clutch portion (144) when the clutch (140) is disengaged.

3. The apparatus of claim 2, further comprising:

a shaft assembly (200) that is connected to the output shaft (1 14) of the starter motor (1 12).

4. The apparatus of claim 3, wherein the first clutch portion (142) is fixed for rotation in unison with at least a portion of the shaft assembly (200).

5. The apparatus of claim 3, wherein the first clutch portion (142) is slidably mounted on at least a portion of the shaft assembly (200) for movement axially with respect to the shaft assembly (200).

6. The apparatus of claim 3, wherein the second clutch portion (144) is restrained from axially movement with respect to the shaft assembly (200).

7. The apparatus of claim 3, wherein the second clutch portion (144) is rotatable with respect to at least a portion of the shaft assembly (200).

8. The apparatus of claim 3, wherein the shaft assembly (200) has a first shaft portion (310) that is fixed to the output shaft (114) of the starter motor (112) for rotation in unison with the output shaft (114) of the starter motor (112) and a second shaft portion (320) that is rotatable with respect to the first shaft portion (310).

9. The apparatus of claim 8, wherein the first shaft portion (310) is connected to the second shaft portion (320) by a rotary joint.

10. The apparatus of claim 8, wherein the output shaft (114), the first shaft portion (310), and the second shaft portion (320) are aligned along a shaft axis.

11. The apparatus of claim 8, wherein the pinion gear (160) is connected to the second shaft portion (320) such that it is restrained from moving axially with respect to the second shaft portion (320).

12. The apparatus of claim 1, wherein a torque transfer path from the starter motor (112) to the pinion gear (160) is defined when the clutch (140) is engaged and disengagement of the clutch (140) eliminates the torque transfer path.

13. The apparatus of claim 1, wherein the clutch (140) is a jaw clutch.

14. The apparatus of claim 1, wherein the actuator (120) includes a solenoid (122) and the moving part (126) of the actuator (120) includes a fork that is engaged with the first clutch portion (142).

15. An apparatus for starting an internal combustion engine having a flywheel (102), comprising:

a starter motor (112) having an output shaft (114) that rotates when the starter motor (112) is energized;

an actuator (120) having a solenoid (122) that is operable to move a fork from a first position to a second position when the actuator (120) is energized;

a shaft assembly (200) that is connected to the output shaft (114) of the starter motor (112);

a jaw clutch (140) that is arranged on the shaft assembly (200), the jaw clutch (140) having a first clutch portion (142) and a second clutch portion (144), wherein the first clutch portion (142) rotates in unison with the output shaft (114) of the starter motor (112), the fork (131) of the actuator (120) is engaged with the first clutch portion (142) to engage and disengage the jaw clutch (140), the first clutch portion (142) is operable to transfer rotation to the second clutch portion (144) when the jaw clutch (140) is engaged, and the first clutch portion (142) is not operable to transfer rotation to the second clutch portion (144) when the jaw clutch (140) is disengaged; and