GB2193543A - Unidirectional clutch - Google Patents

Description

1 GB2193543A 1 SPECIFICATION gear; a rotatably mounted clutch inner

concentric Unidirectional clutch for engine starter with said clutch outer and drivingly connected to the other of said rotor and said pinion., The field of the present invention is starters 70 gear; for automotive engines and, more particularly, said clutch outer and said clutch inner con- an engine starter of the type wherein a unidi- taining oppositely facing, generally parallel, rectional clutch, which is operative to transmit concentrically spaced conical surfaces; and torque in only one direction from the rotor roller means disposed in the space between shaft of a starting motor to a pinion gear 75 said conical surfaces and operative to move meshing with, and driving, a ring gear of an toward the minor diameter end of said sur engine, cooperates with a transmission device faces upon relative rotation between said for operatively connecting the rotor shaft to clutch outer and said clutch inner; the pinion gear -so that when the ring gear said roller means being configured to bindindrives the pinion gear at the start of the en- 80 gly connect said clutch outer and said clutch gine, that is, when a reverse load acts, the inner for movement in unison when said roller overrun of the starting motor due to the re- means is disposed at the minor diameter end verse load is prevented by the cut-off function of said conical surfaces.

of the unidirectional clutch. Due to the relative rotation occurring beEngine starters employing unidirectional 85 tween the clutch outer and the clutch inner clutches are known in the prior art, one such upon actuation of the starter motor and the starter being shown and described, for movement of the roller means toward the example, in United States Patent No. smaller diameter ends of the respective coni 4,440,033. The unidirectional clutch in such cal surfaces, a predetermined time delay oc prior art arrangement comprises wedge- 90 curs before the unidirectional clutch enters its shaped grooves having varying depth formed connected state when the roller means ba in a circumferential direction between the op- come tightly bound between the respective posed peripheral surfaces of a clutch outer conical surfaces. Consequently, the starting connected to the rotor shaft and a clutch in- torque of the starter motor rotor being ner connected to a pinion shaft, and storing 95 transmitted to the pinion gear is damped be rollers biased by springs to the shallower side fore being transmitted to the pinion gear.

of the grooves so that when the clutch outer The described damping can be freely set by drives the clutch inner, the rollers become varying the angle of the taper of the conical bound into the respective recesses to place surfaces of the clutch outer and clutch inner the clutch in its connected state. 100 and by the angle of inclination of the roller Engine starters of the described type are axes.

characterized by various operation noises. One An embodiment of the invention will now of the operation noises generated by a con- be described by way of example and with ventional starter is an impact noise occurring reference to the accompanying drawings, in at the engagement of the pinion gear and the 105 which:

ring gear when the pinion gear suddenly im- Figure 1 is a side elevational view, partly in pacts the ring gear upon actuation of the star- section, of a starter motor and unidirectional ter motor. This noise is generated because clutch apparatus according to the present in the unidirectional cILItch instantaneously enters vention; its connected state -as represented by line b in 110 Figure 2 is a view taken along line 11-11 of Figure 7 and transmits, by impact, the starting Figure 1; torque of the starter motor to the pinion gear Figure 3 is a view taken along line 111-111 of with little or no mitigation or tempering of the Figure 1; applied torque. Figure 4 is an exploded perspective view of To eliminate this problem, the present in- 115 the pinion moving device of the apparatus of vention contemplates provision of an engine Figure 1; starter which damps the starting torque of the Figure 5 is an enlarged view of part of the starting motor in the unidirectional clutch prior unidirectional clutch arrangement illustrated in to its transmission to the pinion gear in order Figure 1; to reduce the force of the impact between the 120 Figure 6 is a view illustrating a portion of pinion gear and the driven gear and, thereby the roller assembly of Figure 51 the operation noise resulting therefrom. Figure 7 is a diagram illustrating the torque According to the present invention there is transmission characteristics of the present em- provided, an engine starter apparatus in which bodiment as compared with an apparatus of a unidirectional clutch transmits torque from 125 the prior art; the rotor of a starter motor to a pinion gear Figure 8 is a diagram illustrating the relation- meshing with the driven gear of an engine, a ship between the relative rotational angle of unidirectional clutch comprising: the members of the unidirectional clutch of the a rotatably mounted clutch outer drivingly present embodiment, on the one hand, and connected to one of said rotor and said pinion 130 noise level, on the other hand; and 2 GB2193543A 2 Figure 9 is a diagrammatic illustration com- the output shaft 23. The transmission device paring operation noise level of the present T includes a driving gear 26 of relatively small embodiment with that of apparatus of the diameter that is formed at the output end por prior art. tion of the rotor shaft 6. A driven gear 27 of

In Figure 1, a transmission housing indicated 70 relatively large diameter is disposed on the generally by symbol H comprises a front hous- same axis as the output shaft 23 and is ing 1 and a rear housing 2 adapted for sepaadapted to mesh with the driving gear 36. A rable assembly. A starter motor M and an unidirectional clutch, indicated generally as C, electromagnetic switch S for actuating the mo- is sandwiched between the driven gear 27 tor M are mounted in mutual parallel relation 75 and the output shaft 23.

in the rear housing 2. The starter motor M As shown best in Figures 5 and 6, the uni- includes a stator 3 consisting of stacked directional clutch C includes the above driven plates and a rear bearing bracket 4 closing the gear 27 integrally formed about the outer peri end of the stator 3. The stator 3, rear bearing phery of the clutch outer 30 that is rotatably bracket 4, and rear housing 2, are fixed to the 80 supported by the output shaft 23. Clutch front housing 1 by means of bolts 5. A rotor outer 30 can undergo limited slidable move shaft 6 of the starter motor M is rotatably ment in the axial direction through a pair of supported by the rear housing 2 and the bear- bearing bushes 8 and 29. A clutch inner 31 ing bracket 4 through a ball bearing 7 and a is formed integrally around the outer periphery bearing bush 8, respectively, and the front, or 85 of the output shaft 23 and is disposed con output end portion, of the rotor shaft 6 pro- centrically with, and inside, the clutch outer jects into the transmission housing H. 30. The clutch outer 30 and clutch inner 31 The electromagnetic switch S includes a possess opposed surfaces formed as conical switch cylinder 10 for supporting a solenoid 9 surfaces 30a and 31a that are spaced from fixed by screw 11 to the rear housing 2. A 90 one another and inclined by a predetermined fixed core 13 is connected to the switch cyl- angle a with respect to their generator axis. A inder 10 through a yoke 12. A movable core plurality of rollers 32 are positioned in circum 14 adapted to move forwardly and ferentially spaced relation about the space be backwardly with respect to the front surface tween these conical surfaces 30a and 31a.

of the fixed core 13 is concentrically disposed 95 In the described embodiment, the rollers 32 within the solenoid 9. A return spring 15 inare held in an inclined attitude by a retainer terposed between the cores 13 and 14 oper- 51 with their axes being angularly offset with ates to normally bias the movable core 14 respect to the axis of the conical surfaces away from the front surface of the fixed core 30a, 31a by a predetermined angle fl. In order 13. The movable core 14 has integrally 100 to ensure that continuous contact between formed thereon a switch operation rod 16 that rollers 32 and both conical surfaces 30a, 31a extends through the fixed core 13, A movable is maintained the clutch outer 30 is biased contact 17 slidably mounted on the tip of the toward the large diameter end of the conical switch operation rod 16 is held at the tip surfaces 30a, 3 1 a by a flat spring 52. The thereof by the force of a compression spring 105 degree of taper of the conical surfaces 30a 18. A terminal cap 19 formed of an insulating and 31a and the direction of inclination of the material is fixed at the rear end of the switch rollers 32 are set in such a fashion that each cylinder 10 by means of a pair of terminal roller 32 rolls towards the smaller diameter bolts 20 that extend through the cylinder end end of the conical surfaces 30a, 31a when wall. A pair of fixed contacts 21 in facing 110 the clutch outer 30 drives the clutch inner 31.

relation to the movable contact 17 are formed The outer axial end portion of the output at the inner end portions of the bolts 20. shaft 23 projects forwardly to the front sur Appropriate conductors (not shown) attached face of the front housing 1. A cylindrical boss to the terminal bolts 20 electrically connect 33a on the pinion gear 33 is connected by a the starter motor M to a power source. 115 spline 34 to the outer periphery of the outer An operation rod 22 with an upturned hook axial end portion of the output shaft 23 so 22a, that projects into the transmission hous- that the former is slidably movable back and ing H, is integrally formed on the movable forth on the latter. A ring gear 35 forming core 14 at the forward end thereof. An output part of the engine drive is disposed to receive shaft 23 is disposed inside the transmission 120 the pinion gear 33 at a predetermined ad housing H at an intermediate position be- vance position of the latter.

tween, and parallel to, the rotor shaft 6 and As shown in Figure 1, the outer end of the the operation rod 22. The output shaft 23 is output shaft 23 extends forwardly beyond the rotatably supported by the front and rear center line L of the ring gear 35 in the axial housings 1, 2 through ball bearings 24 and 125 direction so that when the pinion gear 33 25, respectively, but cannot move in the axial drives the ring gear 35, the inclination of the direction. A transmission device, indicated pinion gear 35 due to th driving reaction is generally as T, is also housed inside the hous- prevented and both gears 33 and 35 can be ing H and is operative to transmit unidirection- thus held in the proper engagement state.

ally the driving force from the rotor shaft 6 to 130 The open end of the cylindrical boss 33a of 3 GB2193543A 3 the pinion gear 33 is closed by a closure plate construction described above, the effective 37 that is caulked or otherwise sealingly con- length of the second anchor arm 48b of the nected to the open end of the boss in order spring 48 is smaller than the first arm 48a.

to prevent intrusion of any dust into the in- The movement of the operation rod 22, how terior of the boss 33a. 70 ever, can be amplified or reduced in being When the electromagnetic switch S is actu- transmitted to the connecting rod 38 by se- ated the pinion gear 33 is caused to be lecting the appropriate ratio of the length of shifted to the engagement position with the these arms.

ring gear 35 by means of a pinion moving The retracted positions of the pinion gear device D disposed on the housing H. The pi- 75 33, connecting rod 38 and shift [ever 47 due nion moving device D has an axially moving to the action of the return spring 43 are re connecting rod 38 that slidably penetrates the stricted by the abutment of the rear surface of axial core portion of the output shaft 23. A the first arm 47a of the shift lever 47 against push flange 38a formed at the front end of the stopper portion 2a formed on the inner the connecting rod 38 is moved by the con- 80 wall of the rear housing 2.

necting rod either backwardly or forwardly be- A pinion housing 49 for storing the rear- tween the closure plate 37 of the cylindrical ward portion of the pinion gear 33 when it is boss 33a and an anchor ring 36 fixed to the retracted from the ring gear 35, is formed at inner wall of the boss 33a. A barrel-shaped the front end of the transmission housing H buffer coil spring 39 is disposed between the 85 and its interior surface 49a diverges- outwardly flange 38a and the closure plate 37. to guide the movement of the pinion gear 33 The rear end of a hollow interior portion of into the pinion housing 49. By means of this the output shaft 23 is of a diameter sufficient arrangement, any moisture, such as rain to form a guide hole 40. A spring-receiving water, washing liquid, or the like, that enters cylinder 41 having an end flange 41a that en- 90 the housing 49 is guided by the tapered sur gages the surface of the hole 40 for slidable face of the interior surface 49a and immedi movement is fixed to the exterior of the con- ately discharged from the housing. As shown, necting rod 38 by an anchor ring 42. A coil the pinion housing 49 is equipped below its spring 43 is disposed in the guide hole 40 interior surface 49a with a drain port 50 for between the bottom thereof and the annular 95 communicating the interior of the housing with shoulder formed by flange 41a so as to bias the outside thereof. To assist moisture dis the connecting rod 38 in the rearward direc- charge, the drain port 50 has a downward tion. gradient toward its outlet. Therefore, even if- As shown in Figure 2, a pair of opposed water enters the pinion housing 49, it can.-,be flats 44 are formed on the outer periphery of 100 discharged immediately by this drain port.50.

the flange 41a of the spring-receiving cylinder On the other hand, an annular closing wall 41 and serve as vent holes for communicating 33b formed integrally across each gear tooth the guide hole 40 with the interior of the at the rear end of the pinion gear 33, pre transmission housing H. Thus, the spring re- vents entrance of the water into the pinion ceiving cylinder 41 in the guide hole 40 can 105 housing 49 through the spaces between the slide without any internal air resistance. respective gear teeth of the pinion gear 33.

As shown specifically in Figure 4, the pinion The wall 33b is also effective to reinforce the moving device D includes a lever holder 45 respective gear teeth.

fixed to the transmission housing H, a shift The operation of the disclosed apparatus is lever pivotally supported by the lever holder 110 as follows. When the starting switch of the through a pivot pin 46, and an overload engine is operated to supply a current to the spring 48, comprising a helical spring wound solenoid 9 of the electromagnetic switch S, about the outer periphery of the pivot pin 46. the movable core 14 is attracted to the fixed The shift lever 47 has a first arm 47a on one core 13 and the operation rod 22 pivots the side of pivot pin 46 that engages the rear end 115 shift lever 47 counterclockwise in Figure 1 of the connecting rod 38 and a second, bifur- around the pivot pin 46 through the overload cate arm 47b on the other side of pin 46 that spring 48. Thus, the first arm 47a pushes extends in the opposite direction from the first forward (to the left as viewed in Figure 1) the arm 47a. Oppositely extending first and sec- connecting rod 38. As the connecting rod 38 ond anchor arms 48a and 48b of the overload 120 advances against the buffer spring 39, the spring 48 engage the rear surfaces of the push flange 38a moves the pinion gear 33 arms 47a and 47b, respectively, of shift lever axially outwardly to mesh with the ring gear 47 and a predetermined torque is imparted as 35. Substantially simultaneously with the actu a set load to the coil portion of the spring 48. ation of the movable core 14 by the fixed The second anchor arm 48b of spring 48 ex- 125 core 13, the movable contact 17 moves into tends transversely between the bifurcate arms contact with the pair of fixed contacts 21 and 47b of the shift lever 47 and the hook 22a of supplies current to, and actuates, the starting the operation rod 22 extends intermediate the motor M to rotate rotor shaft 6.

arms 47b and engages the transversely_ ex- When the rotor shaft 6 rotates, the driving tending portion of the spring arm 48b. In the 130 gear 26 on the end thereof drives the driven 4 GB2193543A 4 gear 27 at a reduced speed so that the clutch range of noise is from 4 to 40', and accord outer 30 which is integral with the driven gear ing to experiments, it has been confirmed that 27 attempts to drive the clutch inner 31, such a 0 value can be obtained by setting the thereby causing relative rotation between the taper angle a of the conical surfaces 30a and surfaces 30a and 31a. This relative rotation, 70 31 a and the angle of inclination j8 of the rol in turn, causes the rollers 32 to roll towards lers 31 to between 1' and 150, respectively.

the smaller diameter end of the conical sur- The following table illustrates the experimen- faces 30a and 31a until the rollers finally betal values:

come tightly engaged or bound between the conical surfaces to interconnect the clutch 75 Experiment a(') 6(') 00) outer 30 and the clutch inner 3 1. Conse- Q 1 15 15 4 quently, the unidirectional clutch C enters its 2 5 6 13.2 connected state. 3 6 8 8.8 As a result of the arrangement, therefore, 4 4 4 23.5 there is a time lag between initiation of rota- 80 5 3.5 3.5 30 tion of the clutch outer 30 and rotation of the 6 1 1 40 clutch inner 31 during which time the starting torque of the starter motor M is damped. Ac- Contrasted with the above, in conventional cordingly, during this period the transmission unidirectional clutches, a 0 value of 3' is the torque of the unidirectional clutch C rises gra- 85 most that can be obtained.

dually as represented by line a in Figure 7 and When the apparatus of the present embodi- sequentially drives the output shaft 23, the ment (A) is compared with a conventional pinion gear 33 and the ring gear 35 so that apparatus (B) as to operation noise, the result the engine operation can be initiated without ing noise levels as shown in Figure 9 are ob the creation of a large impact force as mesh- 90 tained. As is obvious from the diagram, the ing occurs beween the pinion gear 33 and the peak value of the noise is significantly reduced ring gear 35. in the apparatus (A) of the present embodi- When the ring gear 35 rotates at a high ment.

speed upon start of the engine and thereby Accordingly, inpractice of the above de- drives the pinion gear 33 at a greater velocity 95 scribed embodiment, the clutch outer con than the driven gear 27, the unidirectional nected to one of the rotor shaft and pinion clutch C enters its cut-off,state as the rollers gear and the clutch inner connected to the 32 reverse their rotation and roll towards the other are concentrically disposed with respect larger diameter ends of the surfaces 30a, 31a to each other, and a plurality of rollers having on the clutch members 30 and 31. The clutch 100 their axes inclined in the circumferential direc members 30 and 31 are thereby released tion with respect to the generator axis of the from their engaged state and the reverse load opposed conical surfaces on the respective of the ring gear 35 is not transmitted to the clutch outer and the clutch inner are inter starter motor M. Thus, overrun of the starter posed therebetween to define the unidirec motor M is prevented. 105 tional clutch. Thus, when the rotor shaft oper- When the starting switch is deactuated after ates to rotatably drive the pinion gear, the the engine start, the movable core 14 of the relative rotation between the clutch outer and electromagnetic switch S is returned to its ini- the clutch inner causes the rollers to first roll r tial position by the force of the return spring toward the smaller diameter ends of the re 15. At the same time, the movable contact 110 spective conical surfaces, Consequently, the 17 is moved away from the fixed contact 21 starting torque of the starter motor is to deactuate the starter motor M. Retrograde transmitted to the pinion gear after first having;P movement of the movable core 14 also been damped by the unidirectional clutch so causes connecting rod 38 to be simultane- that the impact occurring upon meshing of the ously retracted to its original position by the 115 pinion gear with the ring gear is reduced and force of the return spring 43 whereby the pi- the resultant noise is significantly reduced.

nion gear 33 is disengaged from the ring gear It is to be clearly understood that there are and retracted therefrom to be stored in the no particular features of the foregoing specifi pinion housing 49. cation, or of any claims appended hereto, Figure 8 illustrates the relation existing be- 120 which are at present regarded as being essen- tween the relative rotation angle 0 of the tial to the performance of the present inven clutch outer 30 and the clutch inner 31 before tion, and that any one or more of such fea the unidirectional clutch C reaches the con- tures or combinations thereof may therefore nected state, and the noise occurring upon be included in, added to, omitted from or de meshing of the pinion gear 33 and the ring 125 leted from any of such claims if and when gear 35. The noise can be limited to a low amended during the prosecution of this appli level by increasing 8, but when 8 exceeds cation or in. the filing or prosecution of any 30', the noise reducing effect reaches a subdivisional application based thereon.

stantially constant level.

Claims (1)

1. The value 8 which satisfies an allowable 130 CLAIMS

   GB2193543A 5 1 said rotor and said pinion; 1 1. In an engine starter apparatus in which a unidirectional clutch transmits torque from the said clutch outer and said clutch inner con- rotor of a starter motor to a pinion gear taining oppositely facing, generally parallel, meshing with the driven gear of an engine, a concentrically spaced conical surfaces; and unidirectional clutch comprising: 70 roller means disposed in the space between a rotatably mounted clutch outer drivingly said conical surfaces and operative to move connected to one of said rotor and said pinion toward the minor diameter end of said sur gear; faces upon relative rotation between said a rotatably mounted clutch inner concentric clutch outer and said clutch inner; with said clutch outer and drivingly connected 75 said roller means being configured to bindin- to the other of said rotor and said pinion gly connect said clutch outer and said clutch gear; inner for unitary movement when said roller said clutch outer and said clutch inner con- means is disposed at the minor diameter end taining oppositely facing, generally parallel, of said conical surfaces.

   concentrically spaced conical surfaces; and 80 7. A starter apparatus according to claim 6 roller means disposed in the space between in which said roller means comprises a plural- said conical surfaces and operative to move ity of circumferentially spaced rollers mounted toward the minor diameter end of said sur- for rotation about axes inclined with respect faces upon relative rotation between said to the generator of said conical surfaces.

   clutch outer and said clutch inner; 85 8. A starter apparatus according to claim 7 said roller means being configured to bindin- in which said rollers are cylindrical bodies.

   gly connect said clutch outer and said clutch 9. A starter apparatus according to any of inner for movement in unison when said roller claims 6 to 8 in which the angle of taper of means is disposed at the minor diameter end said'conical surfaces is between about one of said conical surfaces. 90 degree and about 15 degrees.

   2. A unidirectional clutch according to claim 10. A starter apparatus according to claims 1 in which said roller means comprises a plu- 7 and 9 in which the angle of inclination of rality of circumferentially spaced rollers the rotation axes of said rollers is between mounted for rotation about axes inclined with about one degree and about 15 degrees with respect to the generator of said conical sur- 95 respect to the axis of said conical surface faces. generator.

   3. A unidirectional clutch according to claim 11. A starter apparatus according to any of 2 in which said rollers are cylindrical bodies. claims 6 to 10 in which. said clutch outer is 4. A unidirectional clutch according to any drivingly connected to said rotor and said preceding claim in which the angle of taper of 100 clutch inner is drivingly connected to said pi said conical surfaces is between about one nion.

   degree and about 15 degrees. 12. A starter apparatus according to claim 5. A unidirectional clutch according to 11 in which said pinion is axially movably con- claims 2 and 4 in which the angle of inclina- nected to said clutch inner for movement to tion of the rotation axes of said rollers is be- 105 and from connection with said driven gear; tween about one degree and about 15 de- and means for moving said pinion including:

   grees with respect to the axis of said conical shoulder means on said pinion; surface generator. an axially movable connecting rod telescopi- 6. A starter apparatus for an engine having cally received in said clutch inner having a for- a driven gear adapted for connection to a pi- 110 ward end engageable with said shoulder nion, comprising: means; and an electrically operated starter motor includ- means for moving said connecting rod axi- ing a rotor adapted for rotation upon energiza- ally upon actuation of said starter switch.

   tion of said starter motor; 13. A starter apparatus according to claim a starter switch electrically connected to 115 12 in which said connecting rod moving said starter motor to energize said starter mo- means includes:

   tor upon actuation of said switch; a movable core in said starter switch; transmission means for transmitting rota- a pivotally mounted lever interposed be- tional movement of said starter motor rotor to tween said movable core and'said connecting said pinion; 120 rod; and unidirectional clutch means associated with electrically operated solenoid means opersaid transmission means and operative to able to move said core upon actuation of said damp the torque generated by said transmis- starter switch.

   sion means prior to transmission to said pi- 14. A starter apparatus according to claim nion, said unidirectional clutch means includ- 125 13 including return spring means operable to ing: impose retrograde movement on said movable a clutch outer drivingly connected to one of core and said connecting rod upon deactuation said rotor and said pinion; of said solenoid.

   a clutch inner concentric with said clutch 15. A starter apparatus according to claim outer and drivingly connected to the other of 130 14 including contact means on said movable 6 GB 2 193 543A 6 core for simultaneously actuating said starter motor upon actuation of said solenoid means.

   16. A starter apparatus according to claim 14 or 15 including:

   a transmission housing; and recess means on said transmission housing forming a pinion housing concentrically dis posed with respect to said pinion and adapted to receive said pinion in its retracted position.

   17. A starter apparatus according to claim 16 in which said recess means includes an inwardly convergent conical wall; and liquid conductor means communicating with said re cess means for conducting liquid therefrom.

   18. A starter apparatus according to claim 17 in which said pinion comprises an axially elongated annular body having circurnferentially spaced gear teeth disposed about the exterior thereof; and means forming a wall receivable in said pinion- housing and closing the ends of the spaces between said gear teeth.

   Published 1988 at The Patent Office, State House, 66/71 HighHolborn, London WC 1 R 4TP. Further copies may be obtained from The Patent Office, Sales Branch, St Mary Cray, Orpington, Kent BR5 3RD.

   Printed by Burgess & Son (Abingdon) Ltd. Con. 1/87.