US2871708A

US2871708A - Starting apparatus for internal combustion engines

Info

Publication number: US2871708A
Application number: US548349A
Authority: US
Inventors: Louis J Raver
Original assignee: Motors Liquidation Co
Current assignee: Motors Liquidation Co
Priority date: 1955-11-22
Filing date: 1955-11-22
Publication date: 1959-02-03
Anticipated expiration: 1976-02-03

Description

Feb. 3, 1959 J. RAVER' 2,371,708

STARTING APPARATUS FOR INTERNAL COMBUSTION ENGINES Filed Nov. 22, 1955 INV TOR. law: aver HIS ATTORNEY that theentire starting current nit STARTING APPARATUS FOR INTERNAL COMBUSTION ENGINES Louis J. Raver, Anderson, Ind., assignor to General Motors Corporation, Detroit, Mich., a corporation of Delaware Application November 22, 1955, Serial No. 548,349

3 Claims. (Cl. 74--6) engagement with the flywheel gear of the engine to be started and an over-running clutch is provided to connect the motor with the pinion to crank the engine and to permit the pinion to over-run the motor, when the engine becomes self-operative. The type of over-running clutch contemplated in the present invention is the one-way type which will provide a driving connection when the parts are rotated in one direction and will not transmit torque when certain of the parts are rotated in the opposite direction. A clutch of this type, which is frequently used, is one which comprises a driven member which is operatively connected with the pinion and which has an external cylindrical surface and a driving member connected with the electric motor which is located without the driven member which has a plurality of roller camming surfaces in recesses, each of which cooperates with the cylindrical surface of the driven member and a roller to transmit the movement of the driving member to the driven member in one direction of rotation only.

When the engine becomes self-operative, the'driven member is rotated faster by the engine than the driving member is rotated by the electric motor. When this occurs, the driven member tends to over-run the driving member and each roller tends to move toward the widest portion of its recess against a force of a Spring which normally tends to urge the roller into the narrowest portion of the recess. A clutch of the type herein contemplated is more particularly set forth in the patent to Critchfield 2,211,053, which has been assigned to the assignee of the present invention.

It has been found that over-running clutches of the type referred to do not always release, particularly in the event of backfire of the internal combustion engine. It has been further found that on the occasion of backfire, severe stresses are imposed upon the starting apparatus and frequently the clutch member, the starter and the starter shaft are severely damaged. Further, it has been noted that damage has occurred to the entire starting apparatus which includes the electric windings of the starter, the starter shaft and the clutch parts, when the apparatus is used, for some reason with an engine that requires an exceptionally high starting torque. For example, under extremely low temperatures, the engine may be almost immovable, and, after the starting apparatus is actuated so the pinion gear engages the ring gear, the starter will cease to rotate in spite of the fact is imposed over the wind- States are ice ings of a starter. This may cause the windings to quickly burn out or cause the rollers of the clutch to Brinell the roller recesses.

The present invention is directed to remedy the above difficulties and it is an object of the present invention to limit the transmission of torque between the cranking motor and the internal combustion engine which is to be started. This object is accomplished by providing a oneway clutch mechanism of a starter drive with a means that will break the driving connection between the pinion and cranking motor whenever the torque forces applied on the clutch exceed a predetermined value.

Another object of the present invention is to reduce the probability of damage to the pinion gear, the oneway clutch drive, and the parts of the starting motor in a starting motor apparatus for an internal combustion engine by providing a device which will limit the torque which can be applied on the clutch mechanism of the starting apparatus.

A further object of the present invention is to provide the driving member of a roller-type one-way clutch with ratchet teeth and to drive said member with a spring biased driving member which has teeth which mate with the teeth on the clutch member as long as the torque between the members is less than a predetermined value.

It is a still further object of the present invention to utilize a plurality of Belleville type spring members to maintain the driving connection between two driving members which have ratchet teeth arranged so that the driving connection between the members will be broken whenever the torque transmitted through the teeth causes the teeth to ride upon one another and compress the Belleville springs.

Further objects and advantages of the present inven tion will be apparent from the following description, reference being had to the accompanying drawings wherein preferred embodiments of the present invention are clearly shown.

In the drawings:

Figure l is a longitudinal sectional view of the starter drive according to the present invention with the parts in the normal position.

Figure 2 is a longitudinal sectional view of the starter drive in Figure 1 showing the arrangement of the parts when the members are subjected to excess torque.

Figure 3 starter drive showing particularly the shape and arrangement of the torque limiting teeth.

In the drawings, and in Figure 1 particularly, the oneway clutch drive of the starting apparatus according to the present invention, includes a sleeve 20 rotatable on a smooth surface of a starter shaft, not shown, through longitudinally spaced bearings 22. This sleeve has longitudinally extending splines 24 on its outer surface whereon a pinion 26 may longitudinally move and be rotated. A shift collar 28 has internal longitudinally extending splines 30 which are received by a splined surface portion 30a of the starter shaft 3%, which is connected to be driven by the usual electric motor 31. The shift collar 28 is arranged to be longitudinally moved along the splines of the starter shaft by a lever which is not shown and which has a bifurcated end with pins which are received in the annular groove 32 of the collar as set forth in the patent to Critchfield supra. The collar 28 also has external splines 34 on its external surface, the purpose of which will be hereinafter set forth. v

A ring or a driven member 36 is suitably secured, as by welding or brazing, to the sleeve 20. This ring 36 is provided with an external cylindrical surface 38. Interposed between the ring 36 and pinion 26 is a helical spring 40. This spring 40 has one end seated and held in position relative to the pinion 26 by a spring retainer is a sectional view of one of the parts of the 42; and has the other end maintained in position relative to the sleeve 20 and ring 36 by a spring retainer 44. The retainer 44 is provided with a longitudinally extending portion 46, the purpose of which will be hereinafter set forth. A stop. 48. is provided and suitably secured to the end of sleeve 20 to limit the travel of pinion 26 on sleeve 20.

The clutch member of the present invention also has a ring or driving member 50. This ring 59 is provided with a plurality of circumferentially located recesses, not shown, and which are described more fully in the Critchfield reference. These recesses are shaped to receive rollers 5.2 which will transmit torque between ring 50 and ring 36 when the

rings

50 and 36 are rotated in one direction and will not transmit torque when either of the members are rotated in the opposite direction. Interposed between collar 28 and rings 36 and t) and rollers 52 is an annular member 54 which is held in position by a snap ring 56 and which helps maintain the rollers 52 in proper position relative to rings 36 and 5t).

Surrounding the splined portion 34 of collar 28 is an annular member 58 which is also a driving member. This member 58 is provided with an internally splined surface 60 so it may longitudinally move relative to collar 28 and be rotatable therewith. The member 53 is provided with a serrated surface which is preferably formed as shown in Figure 3 to have teeth 62 shaped so the member may ratchet in either direction of rotation. These teeth are adapted to mate with correspondingly shaped teeth 64 which are suitably located on ring, or driving, member 50 to provide a driving connection between the annular member 28 and ring 59. In connection with teeth 62 and 64, it is to be noted that in the event a high torque is to be transmitted, the particular shape of the inclined surfaces thereof will cause the surfaces to ride upon each other, as in Figure 2, and tend to cause a separation of the two members 50' and 53 which is utilized in the present invention to limit the torque between the driving members 51 and 58. Surrounding the parts of the torque transmitting device as shown and annular member 58 and ring 50 is an outer shell 66. The shell has one end crimped over member 53 and constantly urges the annular member 58 to the right as in Figure 1 so that teeth 62 and 64 are normally maintained in engagement with each other. The shell 66 itself is urged to the right through the action of a plurality of Belleville type springs 63 which are held in position by a washer 70, a washer 72 and a snap ring 74. The washer 7t), spring 68, and washer '72 are annular in shape and are further maintained in position by the longitudinally extending portion of spring seat 46.

With the above parts in mind, the operation of the torque transmitting device as shown in the drawings will now be described. When the engine is to be started, the shift lever, not shown, will cause collar 28 to move to the right. The movement to the right of the collar will cause the pinion 26 and sleeve 26 to also be moved to the right so that the pinion is moved into engagement with the ring gear or" the engine, not shown. in the event that the pinion 26 passes directly into engagement with the teeth of the ring gear, the spring 46 will not be compressed. When, however, interference occurs between the gear teeth of the pinion 26 and the ring gear, spring 40 will be compressed until the parts of the clutch are rotated a sufiicient amount so that the compression of spring 40 will cause the pinion 26 to snap forward into its engaging position with the ring gear. The rotation of collar 28 through splines 39 is transmitted through splines 60, annular member 58, teeth 62 and to ring member 50. When ring member St? is rotated, in the proper direction, the rollers 52 will wedge in the recesses and transmit rotation to ring 36 which is secured to sleeve 29 so that the rotation will be further transmitted through .the splines24 to pinion 26 to cause the engine to be ro- 4 tated. In the event of backfire of the engine, the pinion 26 will be caused to rotate faster than the collar 28. When this occurs, normally the rollers 5'2 Will cease to transmit rotation between rings 36 and 59. In the event that the torque imposed by the backfire stresses is severe, the teeth 62 and 64, because of their particular shape, will cause annular member 58 to move on splines 66 to the left, as in Figure 2, against the compression forces asserted by the Belleville springs 68 and shell 66 and the driving connection between ring 5t and the collar 28 will be completely broken. In the event the engine requires a high torque to achieve starting rotation, as when the engine is subjected to extreme cold or has its parts frozen for some other reason, the excess torque applied on collar to the annular member 58 will cause the gear teeth to separate against the force exerted by the Belleville springs 68 so that the starter will rotate independently of the pinion 26 without damage to the starter.

From the above, it is manifest that the driving connection, according to the present invention, will protect the starter apparatus in both the conditions of extreme backfire or under conditions which require extreme torque for starting. Obviously, the amount of torque which will be transmitted between the parts is limited by the strength of the Belleville springs and that these springs may be selected for the particular application involved. Further, the present invention might be used with other types of one-way clutch mechanisms as, for example, a sprag type clutch and will limit the torque which will be applied to the sprag members and the other parts of the starting mechanisms.

While the embodiments of the present invention as herein disclosed constitute preferred forms, it is to be understood that other forms might be adopted.

What is claimed is as follows:

1. In a starting apparatus for an internal combustion engine, the combination comprising; an electric motor, a pinion movable into mesh with a gear of the engine to be started, a sleeve having internal and external splines for moving the pinion, a one-way over-running clutch for transmitting cranking torque between the motor and pinion to crank the engine and permit the pinion to over-run the motor when the engine becomes selfoperative, said clutch having an inside cylindrical member connected with the pinion, an outside clutch cam member, intermediate rollers adapted to become wedged between cam surfaces of the outside clutch cam mem her and the cylindrical surface of the inside clutch memher to drive the pinion when cranking the engine and adapted in conjunction with the outside cam member to be released when the engine becomes self-operative, an annular member having splines on its inner opening adapted to slide on the external splines of the sleeve means, mating teeth on the annular member and outside clutch member, and a means for maintaining the teeth in mating engagement with each other when torque between the motor and engine is less than a predetermined value.

2. In a starting apparatus for an internal combustion engine, the combination comprising; an electric motor, a pinion movable into mesh with a gear of the engine to be started, a sleeve having internal and external splines for moving the pinion, a one-way over-running clutch for transmitting cranking torque between the motor and pinion to crank the engine and permit the pinion to over-run the motor when the engine becomes self-operative, said clutch having an inside cylindrical member connected with the pinion, an outside clutch cam member, intermediate rollers adapted to become wedged between cam surfaces of the outside clutch cam member and the cylindrical surface of the inside clutch member to drive thepinion when cranking the engine and adapted in con unction with the outside cam member to be released when the engine becomes self-operative, an an. nular member having splines on its inner opening adapted to slide on the external splines of the sleeve means, mating teeth on the annular member and outside clutch member, and a means for maintaining the teeth in mating engagement with each other when torque between the motor and engine is less than a predetermined value, said means including an outer sleeve forming an enclosure for said clutch having one end in engagement with said annular member and resilient means between said clutch member and sleeve.

3. In a starting apparatus for an internal combustion engine, the combination comprising; an electric motor, a pinion movable into mesh with a gear of the engine to be started, a sleeve having internal and external splines for moving the pinion, a one-way over-running clutch for transmitting cranking torque between the motor and pinion to crank the engine and permit the pinion to over-run the motor when the engine becomes self-operative, said clutch having an inside cylindrical member connected with the pinion, an outside clutch cam member, intermediate rollers adapted to become wedged between cam surfaces of the outside clutch cam member and the cylindrical surface of the inside clutch member to drive the pinion when cranking the engine and adapted in conjunction with the outside cam member to be released when the engine becomes self-operative, an annular member having splines on its inner opening adapted to slide on the external splines of the sleeve means, mating two-way ratchet teeth on the annular member and outside clutch member, and a means for maintaining the teeth in mating engagement with each other when torque between the motor and engine is less than a predetermined value.

Richards May 13, 1930 Miller May 22, 1951