阅读说明：本技术 用于发动机起动器适配器的超越离合器 (Overrunning clutch for engine starter adapter ) 是由 R.F.夸夫 于 2018-09-10 设计创作，主要内容包括：本文描述了一种用于将发动机起动器可操作地连接至发动机的装置,其中发动机包括发动机曲轴,并且发动机起动器具有带有一定长度的起动器轴、以及与起动器适配器轴径向间隔开并在轴的长度内的蜗杆驱动器的蜗杆或蜗杆螺钉。该装置包括可操作地附接至起动器适配器轴上的蜗轮组件。蜗轮组件包括：蜗轮齿轮或蜗轮,其被定位成与蜗杆接合；以及超越离合器,该超越离合器沿径向位于蜗轮和起动器适配器轴之间并且可操作地接合起动器适配器轴。(An apparatus for operatively connecting an engine starter to an engine is described herein, wherein the engine includes an engine crankshaft and the engine starter has a starter shaft with a length and a worm or worm screw with a worm drive radially spaced from and within the length of the starter adapter shaft. The device includes a worm gear assembly operatively attached to a starter adapter shaft. The worm wheel assembly includes: a worm gear or worm wheel positioned to engage the worm; and an overrunning clutch located radially between the worm gear and the starter adapter shaft and operatively engaging the starter adapter shaft.)

1. A device for operatively connecting an engine starter to an engine, the engine having an engine crankshaft, the engine starter having a starter shaft with a starter shaft length and a worm radially spaced from and within the starter adapter shaft, the device comprising:

a worm gear assembly operatively attached to the starter adapter shaft and comprising:

a worm gear positioned to engage the worm; and

an overrunning clutch radially positioned between the worm gear and the starter adapter shaft and operably engaged with the starter adapter shaft.

2. The device of claim 1, wherein the worm gear assembly further comprises a housing positioned along a length of the starter adapter shaft and substantially radially aligned with the worm, the housing having an outer housing surface and an inner housing surface, the inner housing surface forming a central cavity that houses the overrunning clutch.

3. The device of any one of claims 1-2, wherein the housing comprises:

first and second housing ends;

a first bearing positioned proximate the first housing end and a second bearing positioned proximate the second housing end, the first and second bearings positioned within the housing, and the housing supported on the starter adapter shaft by the first and second bearings.

4. The device of any one of claims 1-3, wherein the housing includes a race having an outer race surface and an inner race surface, the outer race surface engaging the inner housing surface and the inner race surface engaging the overrunning clutch.

5. The device of any of claims 1-4, further comprising at least one liner disk and at least one friction disk, the at least one liner disk and the at least one friction disk being operably positioned between the worm gear and the housing and having a spatial relationship along a length of the starter adapter shaft.

6. The apparatus of any of claims 1 to 5, further comprising:

a biasing member operatively engaging the worm gear and the outer housing surface;

wherein the outer housing surface of the housing comprises a fastening area; and

a fastening member operatively engaging the fastening region and the biasing member, the fastening member positioned to selectively position the biasing member relative to the housing and the worm gear, the selective positioning adjusting a spatial relationship of the at least one liner disk and the at least one friction disk.

7. The device of any one of claims 1 to 6, wherein the housing comprises a first retaining member positioned proximate the first housing end and a second retaining member positioned proximate the second housing end.

8. The device of any one of claims 1 to 7, wherein the worm gear assembly is positioned to transfer torque from the engine starter to the starter adapter shaft for further transfer to the engine crankshaft.

9. The device of any one of claims 1 to 8, wherein the overrunning clutch is selected from the group consisting of a sprag clutch, a roller clutch, a ratchet clutch, a ramp clutch, a slipper clutch, and a wedge ramp clutch.

10. A device for operatively connecting an engine starter to an engine, the engine having an engine crankshaft, the engine starter having a starter shaft with a starter shaft length and a worm radially spaced from and within the starter adapter shaft, the device comprising:

a worm gear assembly operatively attached to the starter adapter shaft and the worm, the worm gear assembly comprising:

a housing positioned along a length of the starter adapter shaft and generally radially aligned with the worm, the housing having an outer housing surface and an inner housing surface, the inner housing surface forming a central cavity that houses the overrunning clutch;

a worm gear located outside the housing to engage the worm; and

an overrunning clutch radially positioned between the worm gear and the starter adapter shaft and operably engaged with the starter adapter shaft.

11. The apparatus of claim 10, wherein the worm gear assembly is positioned to transfer torque from the engine starter to the starter adapter shaft for further transfer of the torque to the engine crankshaft.

12. The apparatus of any one of claims 10 to 11, wherein the housing comprises:

first and second housing ends;

a first bearing positioned proximate the first housing end and a second bearing positioned proximate the second housing end, the first and second bearings positioned within the housing, and the housing supported on the starter adapter shaft by the plurality of bearings; and

a first retaining member positioned proximate the first housing end opposite the overrunning clutch from the first bearing, and a second retaining member positioned proximate the second housing end opposite the overrunning clutch from the second bearing.

13. The device of any one of claims 10 to 12, wherein the housing includes a race having an outer race surface and an inner race surface, the outer race surface engaging the inner housing surface and the inner race surface engaging the overrunning clutch.

14. The device of any of claims 10 to 13, further comprising at least one liner disk and at least one friction disk, the at least one liner disk and the at least one friction disk being operably positioned between the worm gear and the housing and having a spatial relationship along a length of the starter adapter shaft.

15. The apparatus of any of claims 10 to 14, further comprising:

a biasing member operatively engaging the worm gear and the outer housing surface;

wherein the outer housing surface of the housing comprises a fastening area; and

a fastening member operatively engaging the fastening region and the biasing member, the fastening member positioned to selectively position the biasing member relative to the housing and the worm gear, the selective positioning adjusting a spatial relationship of the at least one liner disk and the at least one friction disk.

16. The apparatus of any one of claims 10 to 15, wherein the overrunning clutch is selected from the group consisting of a sprag clutch, a roller clutch, a ratchet clutch, a ramp clutch, a slipper clutch, and a wedge ramp clutch.

17. A device for operatively connecting an engine starter to an engine, the engine having an engine crankshaft, the engine starter having a starter shaft with a starter shaft length and a worm radially spaced from and within the starter adapter shaft, the device comprising:

a worm gear assembly operatively attached to the starter adapter shaft and the worm, the worm gear assembly comprising:

a housing positioned along a length of the starter adapter shaft and generally radially aligned with the worm, the housing having an outer housing surface and an inner housing surface, the inner housing surface forming a central cavity that houses the overrunning clutch;

a worm gear located outside the housing to engage the worm;

an overrunning clutch radially between the worm gear and the starter adapter shaft and operably engaged with the starter adapter shaft; and

wherein the worm gear assembly is positioned to transfer torque from the engine starter to the starter adapter shaft for further transfer of the torque to the engine crankshaft.

18. The apparatus of claim 17, wherein the housing comprises:

first and second housing ends;

a first bearing positioned proximate the first housing end and a second bearing positioned proximate the second housing end, the first and second bearings positioned within the housing, and the housing supported on the starter adapter shaft by the plurality of bearings;

a first retaining member positioned proximate the first housing end opposite the overrunning clutch from the first bearing and a second retaining member positioned proximate the second housing end opposite the overrunning clutch from the second bearing; and

a race having an outer race surface and an inner race surface, the outer race surface engaging the inner housing surface and the inner race surface engaging the overrunning clutch.

19. The apparatus of any of claims 17 to 18, further comprising: a plurality of liner plates and a plurality of friction plates operatively positioned between the worm gear and the housing and having a spatial relationship along a length of the starter adapter shaft.

20. The apparatus of any of claims 17 to 19, further comprising:

a biasing member operatively engaging the worm gear and the outer housing surface;

wherein the outer housing surface of the housing comprises a fastening area; and

a fastening member operatively engaging the fastening region and the biasing member, the fastening member positioned to selectively position the biasing member relative to the housing and the worm gear, the selective positioning adjusting a spatial relationship of the plurality of liner disks and the plurality of friction disks.

21. The apparatus of any one of claims 17 to 20, wherein the overrunning clutch is selected from the group consisting of a sprag clutch, a roller clutch, a ratchet clutch, a ramp clutch, a slipper clutch, and a wedge ramp clutch.

Technical Field

The present disclosure relates to an apparatus, system, and method for transferring torque within a mechanical system, and more particularly to an apparatus, system, and method for transferring cranking torque from an engine starter to an engine.

Background

Combustion engines always require starting power to start the combustion process in the engine. Conventional internal combustion engines are typically started by a dedicated starter motor mounted to the engine. The starter motor is typically electric in nature and is typically connected to the crankshaft of the engine. When the starter receives the signal, it will start cranking while ignition starts in the internal combustion engine. This concept is essentially the same on the engine, whether used on land, sea or in the air.

The starter motor, typically an electric motor, is mounted on the engine and couples the starting torque to the engine in various ways. One method includes a starter adaptor that both mounts the starter to the engine and couples a starter motor torque to the engine crankshaft to facilitate starting of the engine. Typically, the starter adapter provides three functions: (1) mounting/attaching the starter to the engine or to the vicinity thereof; (2) transmitting a starter motor torque to an engine crankshaft during an engine start; and (3) decoupling the starter motor from the starter adaptor drive shaft during normal engine operation, such as during operation of the engine. Alternative starter versions may provide auxiliary functions, such as providing auxiliary functions for a Power Take Off (PTO) or providing a drive location for other accessories (e.g., scavenging pumps, vacuum pumps, etc.).

During engine starting and operation, the starter motor and additionally the starter adapter drive may be subject to normal wear and tear. Typically, the speed of the engine and its crankshaft and gears is much higher than the speed capability of the actual starter motor. Thus, during normal operation of the engine, if the starter is not effectively decoupled from the crankshaft, the starter motor itself will be damaged. This separation typically occurs in the starter adapter driver. Additionally, there is a combustion engine phenomenon known as "kickback" in which the fuel and charge air mixture within the engine is combusted before the piston reaches top dead center of the piston stroke. When this occurs, the crankshaft is strongly forced to rotate in the reverse direction, resulting in extremely high loads on engine components. These loads are transferred to other parts attached or coupled to the crankshaft, such as the starter adapter shaft and possibly the engine starter itself.

Currently, in the field of conventional engines, in particular in aircraft engines, the starter is coupled to a starter adapter driveshaft which is then coupled to the engine crankshaft. As generally depicted in fig. 1 and 2, conventional starting systems use a wrap spring type clutch in an attempt to avoid damage caused by both kickback and engine speeds that may exceed the starter speed. Fig. 1 shows a conventional starter 1 connected to a crankshaft 3 using an adapter 2. The adapter comprises a worm 4 and is connected with a worm gear 5, which worm gear 5 is used for transferring torque from the starter 1 to a starter adapter shaft 6. The conventional adaptor 2 uses a coil spring 7 and a drum 8 on a starter adaptor shaft 6.

In this conventional system, when the starter 1 is energized, torque is transferred through the starter adaptor worm 4 to the starter adaptor worm gear 5. As the worm wheel 5 rotates, the wrap spring 7 gradually comes to bear against the cylindrical drum 8 on the starter adaptor shaft 6. When the wrap spring 7 is sufficiently tight, it engages or "bites" the drum 8, allowing torque to be coupled or transferred to the engine crank gear 9 and ultimately to the crankshaft 3, thereby effecting engine starting. The wrap spring 7 attempts to separate the starter adaptor shaft 6 during engine operation by "wrap spring relaxation". Theoretically, this allows sliding between the drum 8 and the inner diameter of the coil spring 7.

This relaxed state should remain constant throughout normal engine operation or engine operation. However, due to the nature of such conventional starter systems, the failure tendency of conventional starter systems is higher than it should be, and there is a poor containment of the aforementioned kickback phenomenon. For example, the primary failure mode is corrosion of the outer surface of the drum 8 and the inner surface of the coil spring 7. As these features wear, the torque transfer capability of the starter adaptor 2 is reduced, eventually reaching a point where the combination of the wrap spring 7 and drum 8 is no longer able to transfer sufficient torque for engine starting. For example, the normal expected service life of a starter adaptor having this wrap spring design is dependent on the Time Between Overhaul (TBO) rating for the engine. The TBO rating is about 2,000 hours. However, these recoil starter adapter designs often fail at service times below the TBO rating.

In addition, these wrap spring type clutches are also susceptible to damage from the kickback phenomenon. The coil spring 7 increases its connection and the force on the drum 8 during the recoil phenomenon. This forces the starter motor to effectively act as a brake for the recoil force. This transmits a large amount of torque back to the starter 1, which can cause damage. Recoil is reported to damage this type of starter and, in some cases, also introduces debris into the actual engine, resulting in extensive engine damage as well as starter damage.

For many years, attempts have been made to upgrade the starter adapter design to address its life and backlash issues. Neither of these attempts has been successful due to the nature of the wrap spring type clutch and due to the required close contact between the wrap spring 7 and the drum 8 which cannot be properly disengaged in the constant over speed mode of operation.

Accordingly, there is a need for a new engine starting system and method that allows for over-speed operation and reduces the risk of damage due to kickback effects. Preferably, the new system includes a starter adaptor that provides proper decoupling during operation of the engine to protect the starter from the speed of the engine and to protect the starter and the starter adaptor from kickback phenomena. Starters and adapters of this type are lacking in the art.

Disclosure of Invention

The present disclosure relates generally to internal combustion engines, and more particularly to starters and starter motor interfaces to internal combustion engines. For example, an apparatus for operatively connecting an engine starter to an engine is disclosed, wherein the engine includes an engine crankshaft and the engine starter has a starter shaft having a length and a worm or worm screw of a worm drive radially spaced from and within the length of the starter adapter shaft. The device includes a worm gear assembly operatively attached to a starter adapter shaft. The worm wheel assembly includes: a worm gear or worm wheel positioned to engage the worm; and an overrunning clutch positioned radially between the worm gear and the starter adapter shaft and operably engaging the starter adapter shaft.

In some embodiments, the worm gear assembly of the device may further include a housing positioned along the length of the starter adapter shaft. Additionally, the housing may be positioned in general radial alignment with the worm. The housing may include an outer housing surface and an inner housing surface, wherein the inner housing surface forms a central cavity containing the overrunning clutch. The housing may also include first and second housing ends having a first bearing positioned proximate the first housing end and a second bearing positioned proximate the second housing end. The first bearing and the second bearing may be positioned within a housing, wherein the housing is supported on the starter adapter shaft by the bearings. The housing may also include a race having an outer race surface and an inner race surface. The outer race surface may engage the inner housing surface and the inner race surface may engage the overrunning clutch.

The apparatus may also include at least one liner disk and at least one friction disk. At least one liner disk and at least one friction disk are operably positioned between the worm gear and the housing and have a spatial relationship along a length of the starter adapter shaft.

The device may also include a biasing member operatively engaging the worm gear and the outer housing surface. The outer housing surface of the housing may also include a fastening area. The fastening member may be operably engaged to the fastening region and the biasing member. The fastening member may be positioned to selectively position the biasing member relative to the housing and the worm gear. Selective positioning of the biasing member may adjust the spatial relationship of the at least one liner disk and the at least one friction disk. The housing may also include a first retaining member positioned proximate the first housing end and a second retaining member positioned proximate the second housing end.

The worm gear assembly may be positioned to transfer torque from the engine starter to the starter adapter shaft to further transfer the torque to the engine crankshaft. Additionally, the overrunning clutch may be selected from the group consisting of a sprag clutch, a roller clutch, a ratchet clutch, a ramp clutch, a slip clutch, and a wedge ramp clutch.

Accordingly, it is a general object of the present disclosure to provide an apparatus, system, and method for transferring torque from an engine starter to an engine.

It is another object of the present disclosure to provide an apparatus that operatively connects an engine starter to a crankshaft of an engine.

It is a further object of the present disclosure to provide an apparatus that can selectively decouple an engine starter from a crankshaft of an engine.

It is another object of the present disclosure to provide an apparatus for protecting an engine starter during engine operation.

It is a further object of the present disclosure to provide a device that protects an engine starter from forces that may be received from the engine.

It is yet another object of the present disclosure to provide a device that protects the engine starter and engine components from "kickback" from the engine.

It is a further object of the present disclosure to provide a starter adaptor apparatus that connects an engine starter to an engine starter adaptor shaft and can selectively disconnect the engine starter from the engine starter adaptor shaft.

Other and further objects, features and advantages of the present disclosure will be readily apparent to those skilled in the art when the following disclosure is read in conjunction with the accompanying drawings.

Drawings

FIG. 1 is an example of a prior art gear train assembly from an engine starter to an engine crankshaft.

FIG. 2 is an exploded view of the starter and starter adaptor shown in FIG. 1 and includes a housing and an assembly.

Fig. 3 is an exploded view of a device including a worm gear assembly made in accordance with the present disclosure.

Fig. 4 is a cross-sectional view of the assembled device of fig. 3.

FIG. 5 is an assembly view of a device made in accordance with the present disclosure, showing a starter shaft adapter.

Fig. 6 is a cross-sectional view of the assembly shown in fig. 5.

Fig. 7 is a perspective view of a device made in accordance with the present disclosure.

Detailed Description

Referring now to fig. 1-6, devices and systems made in accordance with the present disclosure are shown. In the present disclosure, positional terms, such as "upper," "lower," "side," "top," "bottom," "vertical," "horizontal," and the like, refer to the device in the orientation shown in the drawings. One skilled in the art will recognize that objects according to the present disclosure may assume different orientations when in use.

Referring now to FIG. 3 in general, a device for operatively connecting the engine starter 1 to an engine is shown and generally designated by the numeral 10. The device 10 may also be described as an engine starter adapter 10. As shown in FIG. 1, an engine (not shown in FIG. 3) has a crankshaft 3, and the engine starter may be similar to the engine starter 1 shown in FIGS. 1 and 2. The engine starter 1 may have a starter adapter shaft 12, the starter adapter shaft 12 having a starter shaft length 14 in a worm similar to the worm 4 shown in fig. 1 and 2. The worm 4 is preferably spaced radially outwardly from the starter shaft adapter 12 and within the length of the starter adapter shaft length 14.

The device 10 includes a worm gear assembly 16 operatively attached to the starter adapter shaft 12. The worm gear assembly 16 includes a worm gear 18 positioned to engage the worm 4. An overrunning clutch 20 is also included, the overrunning clutch 20 being located radially between the worm gear 18 and the starter adapter shaft 12 and positioned to operatively engage the starter adapter shaft 12. The overrunning clutch 20 may be described as being positioned within the worm gear assembly 16, or alternatively may be described as being positioned within the worm gear 18. The overrunning clutch 20 may be described as an internally located overrunning clutch 20, with the overrunning clutch 20 being internally located within the worm gear 18.

In a preferred embodiment, the overrunning clutch 20 may be selected from the group consisting of a sprag clutch, a roller clutch, a ratchet clutch, a ramp clutch, a slipper clutch, and a wedge ramp clutch.

The worm gear assembly 16 may also include a housing 22 positioned along the length of the starter adapter shaft 12. This positioning can also be described as being substantially radially aligned with the worm 4. The housing 22 may include an outer housing surface 24 and an inner housing surface 26. The inner housing surface may form a central cavity 28 that houses the overrunning clutch 20.

The housing 22 may also include a first housing end 30 and a second housing end 32, wherein a first bearing 34 is positioned proximate the first housing end 30 and a second bearing 36 is positioned proximate the second housing end 32. The first bearing 34 and the second bearing 36 are located within the housing 22, and the housing 22 is supported on the starter adapter shaft 12 by the first bearing 34 and the second bearing 36.

The housing 22 may also include a race 40, which may also be described as a race ring. The race 40 includes an outer race surface 42 and an inner race surface 44. The outer race surface 42 may engage the inner housing surface 26 and the inner race surface 44 may engage the overrunning clutch 20. Alternatively described, the race 40 may be interference fit into the housing 22 such that there is frictional engagement between the outer surface 42 of the race 40 and the inner surface 26 of the housing 22. Likewise, the inner race surface 44 may have an interference fit with the overrunning clutch 20 such that there is frictional engagement between the inner race surface 44 of the race 40 and the overrunning clutch 20.

The housing 22 may also include a first retaining member 46 and a second retaining member 48. The first retaining member 46 can be positioned proximate the first housing end 30 and the second retaining member 48 can be positioned proximate the second housing end 32. The first and second retaining members 46 and 48 may engage retaining areas 50 and 52 in the housing 22. The retaining members and retaining regions may secure elements such as the overrunning clutch 20, the first bearing 34 and the second bearing 36 within the housing 22.

The apparatus may also include at least one liner disc 54 and at least one friction disc 56. The liner disc 54 may be mechanically coupled to the worm gear 18, while the friction disc 56 may be mechanically coupled to the housing 22. In one embodiment, there are a plurality of liner disks 54 and a plurality of friction disks 56. In another embodiment, there are two friction disks 56 and three liner disks 54. The liner disc 54 and friction disc 56 are operatively positioned between the worm gear 18 and the housing 22 and assist in positioning the worm gear 18 relative to the housing 22. The liner disc 54 and friction disc 56 further facilitate torque transfer between the starter 1 and the starter adapter shaft 12 and ultimately to the crankshaft 3. The liner disc 54 and friction disc 56, wherever present, may be described as having a spatial relationship along the length 14 of the starter adapter shaft 12. Alternatively described, the proximity of the friction disc 56 and the liner disc 54, and the materials from which they are constructed, further facilitate torque transfer between the starter 1 and the starter adapter shaft 12. The tighter the spatial relationship between the liner disc 54 and the friction disc 56, the greater the torque that will be transmitted between the starter 1 and the starter shaft 12 before slippage of the liner disc 54 relative to the friction disc 56 occurs. When there is slip of the liner disc 54 relative to the friction disc 56, torque will not be transferred, which may be described as a slip torque threshold.

A biasing member 58 is also included, the biasing member 58 operatively engaging the worm gear 18 and the outer housing surface 24 of the housing 22. In this embodiment, the outer housing surface 24 includes a fastening region 25 and a fastening member 60 that operatively engages the fastening region 25 and the biasing member 58. The biasing member 58 may be those known in the art, such as a spring. The fastening member 60 and the fastening region 25 may be those mating and fastening means known in the art, such as threads and nuts. In operation, the securing member 60 is positioned to selectively position the biasing member 58. This positioning may be described as selectively positioning the biasing member 58 relative to the housing 22 and the worm gear 18. This selective positioning of the biasing member 58 by the fastening member 60 may also adjust the spatial relationship of the liner disc 54 and the friction disc 56 to further control the slip torque threshold and the amount of torque transferred between the starter 1 to the starter adapter shaft 12. A spacer 59 may be included to further facilitate this interaction.

The device 10 of the present invention having the worm assembly 16 has advantages over conventional techniques in that the positioning of the overrunning clutch 20 allows for over running, e.g., natural running of the engine and at a rotational speed greater than the rotational speed capability of the starter 1. In this way, the overrunning clutch 20 may protect the device 10, and any attached starter 1, from major causes of failure in conventional starter 1 and adapter 2 designs. Additionally, the use of the liner disc 54, friction disc 56, and biasing member 58 incorporates a torque limiting mechanism or torque limiting feature that may further protect the starter adapter apparatus 10, and any engine that may be connected thereto, from damage caused by a "kickback" event. The present device 10, and more particularly the worm gear assembly 16, is preferably designed to be integrated with a conventional starter 1 and crankshaft 3 as known in the art.

In operation, the inventive device 10 has its components positioned to transfer torque from the engine starter 1 to the starter adaptor shaft 12 for further transfer of the torque to the engine crankshaft 3 to start the engine. Torque from the starter motor 1 is transferred through the conventional worm 4 to the worm wheel 18 of the worm gear assembly 16. The worm gear 18 is frictionally coupled to the housing 22, which may also be described as a hub 22, by a liner plate 54 and a friction plate 56, the combination of the liner plate 54 and the friction plate 56 may be described as a friction plate stack. As shown in fig. 3-6, the friction disc stack is preferably comprised of alternating liner discs 54 and friction discs 58.

A tightening member 60, such as a nut, operates with a tightening region 25, such as external threads, on the outer housing surface 24 to apply a compressive force to the biasing member 58, such as a spring. The biasing member 58 compresses the liner disc 54 and the friction disc 56 to apply a preload force to the biasing member 58 to allow for presetting of the slip torque threshold.

The race 40 may be fitted into the central cavity 28 of the housing 22, while the race 40 itself may house the overrunning clutch 20. The clutch 20 may engage the starter adapter shaft 12, and the starter adapter shaft 12 may be coupled to the crankshaft 3 by conventional means such as a pinion gear mesh.

The bearings 34 and 36 support the worm gear assembly 16 on the starter adapter shaft 12, while the retaining members 46 and 48 retain the bearings 34 and 36 and the overrunning clutch 20 within the central cavity 28. The overrunning clutch 20, which may be described as including a clutch insert, and the bearings 34 and 36 may be lubricated by pressurized oil provided by the engine, which may be transferred through the center of the starter adapter shaft 12 through a conductive path 62.

The overrunning clutch 20 also facilitates disengagement of the starter 1 from the starter adaptor shaft 12 during normal engine operation. During this over-run or operation of the engine, the starter adapter shaft 12 will be operatively engaged to the crankshaft 3 and will rotate at the speed of the crankshaft 3. However, the overrunning clutch 20 allows the starter adapter shaft 12 to disengage and rotate independently of the worm gear assembly 16. The bearings 34 and 36 allow the starter adapter shaft 12 to rotate while the remaining worm gear assembly 16 remains free floating and in a non-rotating state relative to the adapter shaft 12.

The device 10 of the present invention may also provide a torque limiting function. This is in turn achieved by friction disc 56 and liner disc 54. The fastening members 60 and the biasing members 58 allow a preload force to be set between the liner plate 54 and the friction plate 56, and ultimately between the worm gear 18 and the housing 22. This preload force, along with the surface characteristics of the surfaces of the liner plate 54 and friction plate 56, creates an amount of torque that can be coupled between the liner plate 54 and friction plate 56 without slipping. The magnitude of this force is also ultimately approximately the same force that can be coupled between the worm gear 18 and the housing 22. This slip torque level may be set to allow sufficient torque to be transferred from starter 1, through device 10, to starter adapter shaft 12 and ultimately to crankshaft 3 for engine starting. This preset level will have the opposite effect when the torque level exceeds the slip torque level and no force is transmitted between the worm gear 18 and the housing 22. In this way, any force from crankshaft 3 that exceeds the slip torque level is not transmitted from crankshaft 3 to starter 1. Finally, during the slip phase, the surface of the friction disc 56 slides on the surface of the lining disc 54 or rotates relative to the surface of the lining disc 54. Since the friction disc 56 is mechanically coupled to the housing 22 and the liner disc 54 is mechanically coupled to the worm gear 18, the housing 22 and the worm gear 18 are allowed to move rotationally independently of one another. In this mode of operation, both surfaces may be described as acting as a bearing system.

Exemplary embodiments

In addition to any that is described above or presently claimed, it is specifically contemplated that any of the following embodiments may be claimed: