US3791225A

US3791225A - Positive control engine starter

Info

Publication number: US3791225A
Application number: US00206706A
Authority: US
Inventors: J Molliet
Original assignee: Individual
Current assignee: Individual
Priority date: 1970-12-15
Filing date: 1971-12-10
Publication date: 1974-02-12
Anticipated expiration: 1991-02-12
Also published as: FR2118380A5; GB1325515A; DE2162218A1

Abstract

A positive control engine starter with a novel coupling between the drive pinion and a helical-spline drive shaft, the coupling including male and female coupling elements cooperating with one another over an axial clearance and an angular clearance. The coupling parts are axially and angularly spring-biased against closing of the clearance gaps, thereby allowing the pinion to yield axially and angularly when tooth collision occurs during engagement. The same spring bias facilitates the pinion retraction after engine firing, by temporarily eliminating the tooth pressure on the gears and by initiating the retracting motion of the male coupling part on the drive shaft.

Description

United States Patent [191 Molliet Feb. 12, 1974 POSITIVE CONTROL ENGINE STARTER [76] Inventor: Jules Henri Molliet, 2, rue

Traversiere, 21 Amay-le-Duc, France [22] Filed: Dec. 10, 1971 [21] Appl. No.: 206,706

[30] Foreign Application Priority Data Dec. 15, 1970 France 7045926 [52] US. Cl. 74/7 R, 64/14 [51] Int. Cl. F02n 15/06 [58] Field of Search 74/7 A, 7 R; 64/14, 15 C [56] References Cited UNITED STATES PATENTS 2,569,267 9/1951 Tobias 74/7 3,410,111 11/1968 Ireland 64/14 1,022,999 .4/1912 Bashaw 64/14 2,944,428 7/1960 Antonidis et a1. 74/7 Digby 74/ 7 X FOREIGN PATENTS OR APPLICATIONS 68,387 3/1914 Switzerland 64/14 Primary ExaminerBenjamin W. Wyche Attorney, Agent, or Firm-Otto John Munz [57] ABSTRACT A positive control engine starter with a novel coupling between the drive pinion and a helical-spline drive shaft, the coupling including male and female coupling elements cooperating with one another over an axial clearance and an angular clearance. The coupling parts are axially and angularly spring-biased against closing of the clearance gaps, thereby allowing the pinion to yield axially and angularly when tooth collision occurs during engagement. The same spring bias facilitates the pinion retraction after engine firing, by temporarily eliminating the tooth pressure on the gears and by initiating the retracting motion of the male coupling part on the drive shaft.

7 Claims, 6 Drawing Figures PATENTED FEB 12 I974 I nvenlor JULES HENRI MOLLI ET y A Home 1 POSITIVE CONTROL ENGINE STARTER BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to starter devices,of the so-called positive control type, for internal combustion engines. Y

2. Description of the Prior Art It is known that starter devices are essentially of two types, i.e. the inertia type and the positive control type. In inertia type devices a pinion is internally threaded and is supported on a threaded drive shaft of the starter motor. When the starter begins to rotate, the internal combustion engine being at standstill, the rotational inertia of the pinion causes it to advance on the threaded drive shaft until the pinion engages a ring gear, usually integral with the flywheel of the engine, after which the starter cranks the internal combustion engine for startup. As soon as; when the latter fires, the starter pinion becomes a driven member instead of a driving member and the pinion moves back on its threaded driving shaft to its rest position, in which it is held by a spring.

Inertiatype starter devices suffer from certain drawbacks and are being replaced to an ever-increasing extent by starters of the so-called positive control type. The main disadvantages of inertia type starter devices is the fact that during the operation of the starter a tooth of the starter pinion may come to abut against a tooth of the ring gear wheel when the longitudinal movement of the starter device takes place, causing the pinion to be blocked against engagement.

' A starter device of the positive control type is moved towards the ring gear by means of fork, which causes the teeth of the pinion to engage those of the ring gear at the moment when the starting action takes place, just before-the motor of the starter is set in operation. After the internal combustion engine is started up, the fork moves the starter device back again, assisted bythe fact that it is the ring gear wheel that drives while the pinion is driven.

To cause a starter device to advance onthe shaft of the starter by means of a fork exerting a longitudinal force, the screw pitch of the pinion and'of its driving shaft must be greater than that of inertia type starter device the driving shaft therefore being helically splinedrather than threaded. In this case, however, the fork action is required to retract the starter device when the engine is started up, just as it was necessary to cause the pinion to engage the ring gear at the beginning of the starting-up operation. Furthermore, in the event of excessive speed of rotation of the engine just after being started up there is a risk of the starter motor likewise being driven at an excessive speed, resulting in its possible damage. In fact, if the excessive speed is considerable the starter device is subjected to a high torque which locks it against axial movement on the driving shaft and thereby maintains the pinion in engagement the ring gear, the fork being thereby prevented from retracting it to its position of rest.

For these reasons starter devices of the positive control type have been'fitted with a free wheel device which separates the pinion angularly and at least partially from the body of the starter'device so that the motor of the starter cannot be driven at excessive speed and the starter-device cannot be locked on the spline shaft.

Various free wheel systems have been suggested, and although some of them function satisfactorily they are comparativaly complex and expensive devices.

SUMMARY OF THE INVENTION An object of this invention is to replace the previously required free wheel systems of positive control type started devices by a simpler and thus less expensive coupling which despite its simplicity will prove equally reliable.

According to the present invention a starter device of the positive control type includes a drive pinion, an internally splined socket mounted on a helically splined drive shaft and a novel coupling between the pinion and the socket, said coupling comprising two parts fitting into one another with clearances between the two parts which allow limited longitudinal and rotational movements between them and damping means biasing the two coupling parts against closing of clearances.

The principle on which the invention is based is as follows to enable the starter device to be retracted to its rest position by means of a fork after the internal combustion engine has been started up and to overcome the friction even if the driving torque exerted by the said engine is extremely high, the socket of the device must be rotationally separated at least momentarily, from the pinion. The free wheel coupling, one part of which separates from the other angularly, but not longitudinally, is a means of doing this. If the pinion can rotate freely over a certain angle only, and if this limited angular clearance is combined with a longitudinal clearance, suitable damping means being provided for each of the clearances, this may suffice to relieve the tooth pressure by which the ring gear retains the pinion and to enable the fork to move back the starter device, as in the case of a free wheel coupling. In other words, the limited angular clearance combines with the longitudinal clearance to momentarily free the gear teeth.

The unexpected fact is that it is not necessary for these clearances to be particularly large to enable a coupling according to the invention to function correctly; experience has shown that even with fairly limited clearances, of the order of a millimeter in the longitudinal direction, and of a few degrees in the direction of rotation (e.g. 3), the return movement of the pinion is effected under satisfactory conditions, without any risk of the started engine driving the starter at excessive speed. This has been demonstrated by numerous starting-up tests carried out by the inventor. This unexpected result, constitutes a major advantage of the invention because these limited clearances make possible a very compact arrangement, a far less complex and therefore less expensive machining and finishing process than in the case with the free wheel connection hitherto used in connection with positive control starter devices. These clearances must nevertheless be appropriately spring-biased.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 shows a coupling for a starter device of the positive control type in accordance with the invention and comprising a male and a female part,

FIG. 2 is a partial section through the male and female parts of FIG. 1' with the male and female parts in a slightly different position,

FIG. 3 is an end view of the female part, FIG. 4 is a plan view of the female part, FIG. 5 is an end view of the male part, and FIG. 6 is a plan view of the male part.

DESCRIPTION OF THE PREFERRED EMBODIMENT These figures as a whole show a coupling according to the invention, intended to connect a pinion 2 of a starter device of the positive control type with an internally fluted socket 3, normally mounted on the helical spline shaft 4 of a sTarter motor (not shown). This coupling comprises a pinion 2, integral with a female part whose general form is that of a cylinder notched at the end opposite the pinion to provide a rectangular recess 21, thus forming a pair of jaws 27 and 28, and bored out to form a cylindrical opening 22 (FIG.3). The said female part also includes a circular recess 29 (FIG.2), of the same diameter as the socket 3, and two blind bores 23 and 24, located symmetrical with resepect of the axis of the pinion 2 and of the female part 20. Finally, the jaws 27 and 28 of the female part are provided on their outer periphery with circular grooves and 26, which can be seen more clearly in FIGS. 3 and 4 lntegrally with the socket 3, there is provided a male part 30 taking the general form of a letter T and of such dimensions as to enable it to be introduced, with a certain clearance, into the rectangular recess 21 of the female. The branches 31 and 32 of the T terminate in a part rounded portion 33 of the same diameter radius as the female part 20 and are provided on the outer surface with circular grooves 34 and 35, somewhat larger in the axial direction than the grooves 25 and 26 of the female part. Finally, each of the branches 31 and 32 has a cylindrical blind bore 36 and 37 respectively, symmetrical with respect to the axis of the socket 3 but asymmetrical in respect of the general planes of symmetry of the male part 30 Spring-mounted pushers 41, 42, 43, 44 are adapted to be accomodated in the bores 23, 24, 36, 37 and a retaining ring 126 of spring steel, of the same diameter as the circular grooves 25 and 26 snaps into the latter.

When a coupling of this type is assembled (FIGS. 1 and 2), the female and male parts 20 and 30 respectively fit into each other, the spring-mounted pushers 41 44 occupy their respective bores, and the spring ring 126 fits into the grooves 25, 26 34, to connect the two parts together. The end 38 of the socket 3 (FIG. 6) is accomodated in the recess 29 (FIG. 2) of the female part, resulting in highly satisfactory centering. It does not, however, abut the base of the recess (FIG. 1), but is biased back by the spring-mounted pushers 41 and 42, acting on the branches 31 and 32 of the male part. A longitudinal clearance 51 thus exists between the branches 31 and 32 and the base of the jaws 27 and 28, as well as a clearance 52 to the right of the spring ring 126 in the grooves 34 and 35 of the branches 31 and 32, these grooves being, as already stated, larger than the corresponding grooves 25 and 26 of the female part 20.

Furthermore, the pushers 43 and 44, acting in the same direction of rotation of the branches with respect to the jaws, result in a rotational clearance 53 between the branches and the jaws, on the side visible in FIG. 1.

The starter device thus assembled forms an articulated assembly, having both a-longitudinal and a rotational clearance, compensated by the two longitudinal dampers and the two transversal dampers which constitute the pushers 41, 42, 43 and 44. The thrust of the longitudinal dampers is limited by the spring ring 126. The centering of the two parts is satisfactorily ensured by the bearing engagement between the extremity 38 of the socket 3 in the recess 29.

A starter device fitted with a coupling according to the invention operates as follows 1 At the moment of starting, a fork (not shown), controlled by a solenoid or by a manual pull device, acts on a collar shown in broken lines at 54, shifting the device as a whole towards the left, in the manner already known per se. The pinion 2 approaches the ring gear (not shown) and engages it. At the end of the travel the pinion 2 comes to abut against a stop 40 at the end of the spline shaft 4 the pushers 41 and 42 undergo compression and the clearance 51 is taken up (position shown in FIG. 2). If, at the moment when the pinion is about to mesh with the ring gear a tooth of the former comes to abut against a tooth of the latter, the socket 3 is able to continue its axial movement, compressing the still extended pushers 41 and 42 (position shown in FIG. 2) the socket thereby rotates to a small angle against the bias of radial (pushers 43 and 44 sufficiently to overcome the abutment between the aforementioned teeth. The pinion then meshes with the ring gear and at the end of its travel, abutting against the stop 40, the clearance 51 is taken up as already described. The motor of the starter is now set in operation, cranking the internal combustion engine, the pushers 43 and 44 being compressed, and the clearance 53 taken up.

At the completion of when the engine rotates of its own power, the starting operation, the ring gear tends to move more rapidly than the pinion, and the four pushers expand simultaneously, nullifying the tooth pressure exerted by the ring gear (which has become a driving gear) on the pinion during a period which, although extremely short, is sufficient to enable the fork to retract the starter device to the right toward its position of rest. After this retraction has commenced there is no reason why this movement should not continue, since, due to the helix of the spline shaft, the greater the speed gathered by the device in its movement towards the right, the greater the extent to which the stress tooth pressure exerted by the ring gear on the pinion will be relieved: the retracting movement of the starter device thus continues.

I claim:

1. In a positive control engine starter where the drive pinion is advanced and retracted on the starter drive shaft by means of an independent control element such as a solenoid-operated shifting fork or the like, a coupling assembly between the pinion and the drive shaft comprising in combination:

a first coupling member connected to the rear of the drive pinion, the pinion and first coupling member being guided on the drive shaft for rotation and axial displacement relative thereto between a forward engagement position and a retracted rest position;

a second coupling member arranged axially behind the first coupling member and including a rotational connection with the drve shaft allowing of axial displacement thereon along a helix whose axial reaction force under cranking torque is directed toward the drive pinion;

means for angularly connecting the first and second coupling members in such a way that the two members engage one another rotationally in both directions, with an angular clearance permitting a limited angular displacement between the coupling members;

means for angularly biasing the coupling members against each other in the direction in which the pinion and first coupling member are angularly retarded relative to the second coupling member in the rotational sense of cranking; and

means for axially biasing the drive pinion away from the second coupling member independently from the angular biasing means so as to allow a relative approaching motion therebetween, when the pinion encounters an obstacle during its forwardmo tion into gear engagement;

the drive pinion and the first coupling member are solidary with one another, and the axial biasing means are arranged between the first and second coupling members;

the coupling assembly further comprising:

means for axially connecting the first and second coupling members in such a way that the two members engage one another axially in both directions, with an axial clearance permitting a limited axial displacement between the coupling members.

2. A coupling assembly as defined in'claim 1, wherein the axial biasing means and the angular biasing means include compression springs betweeen the first and second coupling members.

3. A coupling assembly as defined in claim 1, wherein the male and female coupling members form a substantially cylindrical common periphery in the area of axial engagement, the circumference of said cy-' lindrical periphery being formed in part by nonrecessed portions of the female coupling member and in part by the axial protrusions of the male coupling member; and

the axial connecting means between the coupling members includes a circumferential groove traversing both the male and female portions within the common cylindrical periphery, and a retainer ring received within said circumferential groove which engages the groove portions of both coupling members with the indicated axial clearance.

5. A coupling assembly as defined in claim 4, wherein the circumferential groove of the axial connecting means has a groove width in the circumferential portions of the female coupling substantially of the same dimension as the retainer ring, and a groove width in the circumferential portions of the male coupling which is axially larger by at least the amount of the indicated axial clearance.

6. A coupling assembly as defined in Claim 4,

wherein the first coupling member is the female member, having a substantially cylindrical outer periphery, an enlarged recessed center bore in its rear portion, and a transverse slot therethrough forming two oppositely located rectangular axial recesses in the rear portion of the coupling member; and

the second coupling member is the male member,

having a cylindrical trunnion adapted to be received and centered in the center bore of the female member, and a pair of parallel-faced lobes adapted to be received in the two axial recesses of the female member with the indicated angular clearance, the radial ends of the lobes having a radius corresponding to that of the cylindrical periphery of the female coupling member.

7. A coupling assembly as defined in claim 6, wherein the axial biasing means includes axially oriented compression springs arranged in the bottom of the axial recesses of the female coupling members so I as to bias the cooperating axial protrusions of the male coupling member out of these recesses; and the rotational biasing means includes circumferentially oriented compression springs arranged between opposing radially oriented surface portions of the axial recesses in the female coupling member on the one hand and the cooperating axial protrusions of the male coupling member on the other hand.

Claims

1. In a positive control engine starter where the drive pinion is advanced and retracted on the starter drive shaft by means of an independent control element such as a solenoid-operated shifting fork or the like, a coupling assembly between the pinion and the drive shaft comprising in combination: a first coupling member connected to the rear of the drive pinion, the pinion and first coupling member being guided on the drive shaft for rotation and axial displacement relative thereto between a forward engagement position and a retracted rest position; a second coupling member arranged axially behind the first coupling member and including a rotational connection with the drve shaft allowing of axial displacement thereon along a helix whose axial reaction force under cranking torque is directed toward the drive pinion; means for angularly connecting the first and second coupling members in such a way that the two members engage one another rotationally in both directions, with an angular clearance permitting a limited angular displacement between the coupling members; means for angularly biasing the coupling members against each other in the direction in which the pinion and first coupling member are angularly retarded relative to the second coupling member in the rotational sense of cranking; and means for axially biasing the drive pinion away from the second coupling member independently from the angular biasing means so as to allow a relative approaching motion therebetween, when the pinion encounters an obstacle during its forward motion into gear engagement; the drive pinion and the first coupling member are solidary with one another, and the axial biasing means are arranged between the first and second coupling members; the coupling assembly further comprising: means for axially connecting the first and second coupling members in such a way that the two members engage one another axially in both directions, with an axial clearance permitting a limited axial displacement between the coupling members.

2. A coupling assembly as defined in claim 1, wherein the axial biasing means and the angular biasing means include compression springs betweeen the first and second coupling members.

3. A coupling assembly as defined in claim 1, wherein the first and second coupling members are in the form of male and female cooperating parts; the angular connecting means between the coupling members including one or several off-center axial recesses in the female coupling member and matching axial protrusions in the male coupling member engaging the female recesses with the indicated angular clearance.

4. A coupling assembly as defined in claim 3, wherein the male and female coupling members form a substantially cylindrical common periphery in the area of axial engagement, the circumference of said cylindrical periphery being formed in part by non-recessed portions of the female coupling member and in part by the axial protrusions of the male coupling member; and the axial connecting means between the coupling members includes a circumferential groove traversing both the male and female portions within the common cylindrical periphery, and a retainer ring received within said circumferential groove which engages the groove portions of both coupling members with the indicated axial clearance.

6. A coupling assembly as defined in Claim 4, wherein the first coupling member is the female member, having a substantially cylindrical outer periphery, an enlarged recessed center bore in its rear portion, and a transverse slot therethrough forming two oppositely located rectangular axial recesses in the rear portion of the coupling member; and the second coupling member is the male member, having a cylindrical trunnion adapted to be received and centered in the center bore of the female member, and a pair of parallel-faced lobes adapted to be received in the two axial recesses of the female member with the indicated angular clearance, the radial ends of the lobes having a radius corresponding to that of the cylindrical periphery of the female coupling member.

7. A coupling assembly as defined in claim 6, wherein the axial biasing means includes axially oriented compression springs arranged in the bottom of the axial recesses of the female coupling members so as to bias the cooperating axial protrusions of the male coupling member out of these recesses; and the rotational biasing means includes circumferentially oriented compression springs arranged between opposing radially oriented surface portions of the axial recesses in the female coupling member on the one hand and the cooperating axial protrusions of the male coupling member on the other hand.