KR20040091078A - Electric starter with a damping stop for the starter drive assembly - Google Patents

Abstract

The present invention relates to an electric starter for an automobile combustion engine. The starter of the present invention comprises a starter drive assembly 18 with pinion 14 and a freewheel transmission device 20 connected to the control lever 16. The pinion is capable of axially sliding on the output shaft 12 between a stationary position that is separate from the ring gear 15 and an operating position that engages the ring gear. One stop element 30 is disposed on the output shaft 12 in order to limit the movement of the starter drive assembly 18 in the operating position, the stop element 30 in which the pinion 14 is ring geared. It consists of an elastic element 40 and a metal ring 31 which are arranged to alleviate the impact when engaged with the and reduce noise.

Description

ELECTRIC STARTER WITH A DAMPING STOP FOR THE STARTER DRIVE ASSEMBLY}

As shown in FIG. 1, a vehicle starter according to the prior art includes an electric motor 100, and the output shaft 12 of the electric motor has a flywheel to ensure starting of an automobile combustion engine (not shown). The moving pinion 14 which is interlocked with the toothed ring gear 15 is mounted. The pinion 14 is mounted to be slidable on the output shaft 12 between a stop position separate from the toothed ring gear and an operating position engaged with the toothed ring gear, the toothed ring gear rotating on the crankshaft of the automobile combustion engine. Connected. The electric motor 100 of the starter is coupled to an electromagnet contactor CT placed thereon, the contactor of the current supply function of the electric motor 100 and the movement of the pinion 14 between the stop position and the operating position. It has a dual function. The voltage supply of the electromagnet of the contactor CT is controlled by the operation of a switch key which opens the electrical circuit towards the battery following the closing of the contact point CT's main contact CP.

The moving shaft 23 of the contactor CT is mechanically connected to the starter drive assembly 18 comprising the pinion 14 and the freewheel transmission device 20 via a control lever 16. The control lever 16 in the form of a bracket is mounted to rotate on the shaft 22, and the freewheel 20 is fitted axially between the pinion 14 and the linkage shaft 24, and the linkage shaft 24 is It is operated by the control lever 16. The output shaft 12 is rotatably mounted in the case 26 via a pair of supports 28, 29.

The drive shaft 24 comprises two spiral grooves of complementary shape, one groove on the output shaft 12 and the other in the inner cylinder of the drive shaft 24.

In this way, the pinion 14 is interlocked with the interlocking shaft 24 by the transmission device 20 with a freewheel. The transmission device engages the pinion 14 in a rotational direction corresponding to the rotational direction of the output shaft 12 during the normal starting process, while the rotational speed of the pinion 14 is faster than the rotational speed of the drive shaft 24. In this case, mechanical coupling through rotational interlocking is blocked. At the end of the combustion engine, the transmission device 20 with the freewheel prevents the pinion 14 connected to the ring gear from damaging the electric motor by rotating the rotor of the electric motor 100 too fast. This situation can occur if the driver does not shut off the contactor immediately after starting.

One stop element 30 is placed on the output shaft 12 on the side of the support 28 to limit the movement of the starter drive assembly 18 within the operating position when the pinion 14 rotates the heat engine. Lose. The stop element 30 is axially fixed on the shaft 12 by a ring 32 placed in an annular groove 34.

When power is supplied to the starter, the pinion 14 is horizontally moved in the arrow direction F through the lever 16. The speed at which the front face 36 of the pinion 14 comes into contact with the support face 38 of the stop element 30 is significantly increased through the starter drive assembly 18. Due to this increased speed, the weight of the starter drive assembly 18, and the mechanical rigidity of the parts in contact, shock and noise are generated. In particular, the impact is caused by mechanical stresses which are momentarily elevated on the pinion 14 and the stationary element 30, and the noise is short but can be perceived by the driver and the people around the vehicle.

In order to solve the problems caused by the above mechanical stress, methods for improving the mechanical resistance of the parts in contact, such as using a high toughness steel, performing an artificial heat treatment method, or adjusting the weight Already proposed. However, these methods may solve the problems related to mechanical aspects, but cannot solve the noise generation problem.

The present invention relates to an electric starter for an automobile combustion engine,

An electric motor with one rotor coupled to the output shaft,

A pinion for interlocking the toothed ring gear of the flywheel of the combustion engine, the pinion being capable of axially sliding on the output shaft between a stationary position which is separated from the ring gear and an operating position which engages the ring gear. Starter drive assembly,

A freewheel transmission device connected to the control lever for horizontal movement of the starter drive assembly,

A stop element disposed on the output shaft to limit movement of the starter drive assembly in the operating position.

1 is a partial cross-sectional view of a starter drive assembly according to the prior art,

2 is a stop element cross-sectional view of the starter drive assembly according to the invention,

3 shows a variant embodiment of the shock absorber coupled to the stop element shown in FIG. 2, FIG.

4 is a graph showing how the compressive force exerted by the pinion on the stationary element changes over time (curve 1 relates to a starter according to the prior art, curve 2 relates to a starter according to the invention),

5 and 7 are cross-sectional views of two alternative embodiments of the stop element shown in FIG. 2, FIGS.

6 is a graph relating to the compressive force performed on the stationary element shown in FIG.

8 shows an embodiment of a starter drive assembly coupled with a contactor according to the invention,

9 and 10 are axial cross-sectional views of two alternative embodiments of the embodiment shown in FIG.

FIG. 11 is a front view of the elastic washer mounted to the starter drive assembly shown in FIGS. 9 and 10.

The present invention aims to reduce the noise produced by the starter at the end of the pinion being engaged with the heat engine ring gear.

The device according to the invention is characterized in that the stationary element consists of an elastic element and a metal ring mounted to absorb the shock that occurs when the pinion is engaged. The material of the elastic element is selected according to the elasticity characteristics, impact absorption characteristics and mechanical characteristics. Through such a shock absorber according to the invention it is possible to limit the compressive force, which is due to the dispersion time of the impact energy occurring on the system according to the invention occurring on a system according to the prior art in which metal-to-metal contact occurs. This is because the dispersion time is longer than the impact energy dispersion time. The result is reduced noise generation during the start up process.

According to one preferred embodiment, the elastic element has an annular shape with a rectangular cross section and constitutes an end of synthetic rubber material fixed to the ring. The end is deformed as a pinion is applied to the pinion and pressurized. The elastic element includes means for obtaining sufficient firmness to withstand the transfer pressure. In order to achieve this effect, the front face is equipped with protrusions which play a role of imparting gradually increasing braking force to the pinion.

Further features according to the invention as follows may be used individually or in complementary combinations:

The ring of the stop element may be placed with a projection towards the pinion to limit the pressure transmitted to the cushioning contact,

-Cushioning contacts made of synthetic rubber may be provided with counter elements, for example washers made of metallic material, where the pinion contacts.

Further advantages and features of the present invention will be described in more detail through one embodiment given as a non-limiting example below in conjunction with the accompanying drawings.

As shown in FIG. 2, the stop element 30 consists of a metal ring 31 and an elastic element 40, which elastic element is subjected to the impact that occurs when it engages with the shear surface 36 of the pinion 14. It abuts against the support surface 38 of the ring 31 for relaxation. The shape of the elastic element 40 is an annular shape having a rectangular cross section, and is made of a material selected according to elasticity, impact absorbability and mechanical properties.

When casting and using synthetic rubber, there is an advantage in that the size of the device can be adjusted so that the shock absorber can have a limited contact surface at the initial contact with the pinion 14. The synthetic rubber deforms as pressure is applied to the elastic element 40 by the driving force of the pinion 14. The contact surface gradually increases, and the degree of deformation of the component gradually decreases.

As shown in FIG. 3, protrusions 42 may be formed on the front end surface 52 of the elastic element 40 to obtain firmness that can withstand the transfer pressure. As the pressure transmitted thereby increases, the pinion 14 is gradually given a strong braking force. This reduces the point of impact and reduces noise.

4 shows a graph of compressive force over time, with the cushioning effect by the elastic element 40 limiting the peak of the instantaneous compressive force generated by dispersing the impact energy over a longer time. The torque transmitted by the starter generates an impingement force F _e on the stop element 30 via the helical groove of the starter drive assembly 18. In the case of a starter according to the prior art, it can be seen that such contact occurs in the form of metal to metal such that the highest impact force F1 _p appears at time t1 in curve 1 of FIG. 4. On the other hand, it can be seen that the highest impact force F2 _p is lower than F1 _p and the duration t2 is longer than t1 in the curve 2 in which the cushioning effect of the elastic element 40 appears. Thus the strength of the impact is reduced and distributed over longer periods of time. These are very useful factors in reducing noise generation.

As shown in FIG. 5, the ring 31 of the stop element 30 may have a cylindrical projection 44 in the direction of the pinion 14, which is around the shaft 12 and the inner wall of the projection 44. An annular housing 46 of rectangular cross section ABED is formed therebetween. The shock absorber 40 is formed such that its volume has an end of a rectangular cross-section DFCG less than or equal to the volume of the ring housing 46.

The protrusion 44 on the ring 31 can limit the pressure delivered to the shock absorber 40. This is especially true if the starter is operating abnormally. As shown in FIG. 6, when exceeding the starter torque corresponding to the compression force F _u , the pinion 14 abuts against the protrusion 44. At this time, even if the impact generated by the pinion 14 generates a compressive force F _M greater than F _u , the compression X _m transmitted to the end of the shock absorber 40 will be limited, and the surplus compressive forces F _M -F _u are exceptional. If this occurs it will be delivered to the protrusion 44 of the stop element 30 provided to resist it. As such, the shock absorber 40 is protected to resist excessive shock that can destroy itself.

For example, the shock absorber 40 made of synthetic rubber is damaged while friction occurs on the surface in contact with the pinion 14, thereby reducing the shock absorbing effect. In order to preserve its original qualities, the front face 52 of the shock absorber 40 may be equipped with an opposing component 48 to which the pinion 14 abuts.

The counter part 48 may be composed of a washer made of a processed metal material or the like. Of course, the opposing component 48 may be placed on the front face 52 of the shock absorber 40 depending on whether the protrusions 42 are formed on the front face.

Assembly of the resilient element 40 may be effected through adhesive fixation, fit fixation, clamp fixation, tightening fixation, or any other known method. The elastic element 40 may be mounted so as to be lightly tightened on the shaft 12 so as to be translating and rotating with inherent elasticity so as to resist movement caused by vibration of the heat engine.

Of course, the elastic element 40 may be composed of a metal washer having elastic deformation characteristics, in particular, a lock washer, a conical washer, a block in which a plurality of stainless steel wires are closely twisted.

As shown in FIG. 1, a device with a freewheel 20 is a type that includes a roller known in the art. As soon as the pinion 14 abuts against the stop element 30, an impact occurs that causes the pinion 14 and the stop element 30 to generate a momentary high mechanical stress. According to the invention, this shock can be reduced due to the shock absorber 40 described above. If the freewheel is of a type comprising a roller, there is also a radial cushioning element by radial deformation of the elastic bell 50 under the radial pressure of the roller as soon as the pinion reaches the stationary element. The result is a gradual torque on the stop element, on the one hand by means of the shock absorber 40 and on the other by the radial deformation of the freewheel with rollers.

As described in French patent FR 2 826 695, a freewheel made in the form of a conical clutch can be fitted to the car starter for improved accuracy. This is shown in the starter shown in Figures 8-11. Starter drive assemblies with this type of conical clutch are advantageous in terms of light weight, less space, and reduced component count.

In these figures a connecting device with a conical clutch 7 for connecting the pinion 14 to the carrier 24 is shown (see FIG. 8). The conical clutch 7 has a first friction surface 8, first surface in the form of a truncated cone associated with the pinion 14 and a second friction surface in the form of a truncated cone corresponding to the carrier 24 and associated with the carrier 24. (8 ', second surface) (see FIGS. 9 and 10). The connecting device comprises on the one hand a hollow connecting part having a bottom extending to an axial annular edge towards either of the pinion 14-the carrier 24, on the other hand the pinion 14-the carrier. Resilient devices 10 for axial movement supported by the first stop element associated with the connecting part for acting on the second stop element 4 'associated with one of the 24 parts. The elastic devices 10 are supported by the sides 1b (see FIG. 9), 12b (see FIG. 10) of the connecting part. The side comprises on the one hand one of the first and second friction surfaces 8, 8 ′, on the other hand the side 8, 8 ′ being more clearly supported by the inner edge. The pinion 14 is coupled to one of the carriers 24 via the bottom of the connecting part. One groove 51 is formed to interlock with the control lever 16 in the form of a bracket.

The contact diameter of the first friction surface 8 and the second friction surface 8 'here is larger than the diameter of the circular part of the tooth head of the pinion.

In the figures, the first or second friction surfaces 8, 8 ′ supported by the sides 1b, 12b are axially longer than the other second or first friction surfaces 8 ′, 8. .

The elastic devices 10 are supported by the free ends of the sides 1b and 12b and extend in an axial direction with respect to the other second or first friction surface 8 ′, 8.

The larger diameter axial ends of the other friction surfaces 8 ', 8 are defined by transverse shoulders. The transverse shoulder comprises a second stop element 4 ′, which is an elastic device having an axial movement between the first stop element and the second stop element 4 ′ supported by the free end of the connecting part side. 10) form an axial compression force.

The transverse shoulder extends toward its inner periphery through an generally axially facing annular support 4 ", which supports at least partly to accommodate the elastic devices 10 in axial motion. Together to limit the movement of the material.

Elastic devices in axial motion here exhibit the form of an elastic ring and are placed in a groove at the inner edge of the free end of the side.

The resilient devices may have the form of hooks which are elastically connected to the inner circumference of the free end of the connecting part side as the variant.

As shown in FIG. 11, the elastic device 10 in axial motion can extend circumferentially, including a flange 10b that can be deformed axially.

The flange 10b is concavely curved in the axial direction and includes a ring washer 10a. In FIG. 11, the axial movement of the elastic devices 10 includes a ring washer 10a surrounding the elastic flange 10b. These elastic flanges preferably have a fixed region 10d connected to the inner edge of the ring washer 10a. The flange 10b protrudes circumferentially on both sides of the fixed region 10b to form an arm in the form of an annular sector extending. The ring washer 10a has a radial slit 10g which causes one fixed region 10d to be separated in symmetrical form. A total of four arms 10b are formed, two arms 10b per fixed region.

As a variant, the first stop element may be formed of a stop ring or an elastic ring, which is preferably arranged in a groove formed at the inner edge of the free end of the side. Thus, the elastic devices 10 are at least a dish spring washer (Belleville). spring washer) or at least a corrugated ring washer. It may also constitute a conical spiral spring supported by an elastic ring or stop ring for movement in the carrier (see FIG. 9) or pinion (see FIG. 10) to control the tightening of the friction surfaces 8, 8 ′.

In another embodiment, the first stop element can be fixedly connected on the free end of the side.

In all of the above embodiments, the axially moving elastic devices include elastic ring washers.

In all the above embodiments, the free end of the side has an annular extension.

As shown in Fig. 9, the connecting part has a conical shape. It is preferable that one of the first and second friction surfaces 8, 8 'has a groove for contact with the other surface for the dust discharge and the separation of the friction surfaces 8, 8'. At least one of the first and second friction surfaces 8, 8 ′ is preferably provided with a friction reinforcing material.

As shown in Fig. 9, the pinion 14 is integral with the connecting piece which is generally in the form of a bell, and the connecting part is fixed on the pinion.

As shown in FIG. 10, the entire structure may have an inverted form in the opposite direction, with the result that the connecting parts are connected to the starter drive assembly. The assembly has a cylindrical outer cover 12b around its outer circumference.

In one embodiment the carrier can be obtained, for example, by casting with a plastic material. As shown in FIG. 8, it can be seen that the force is dissipated when the pinion 14 is in contact with the work stop element 30.

More specifically, the initial pressure of the elastic devices between the stop elements generates friction torque between the carrier and the pinion. The torque value is always greater than the torque value required for screwing or advancing the starter drive assembly on the shaft 12 in its configuration.

This condition automatically starts the starter drive assembly movement between the stop position and the advance position. The forward position refers to the position where the starter drive assembly abuts against the work stop element 30 at the beginning of the process of interlocking the automobile engine via the start ring gear. When the pinion reaches the stop element 30, a stoppage occurs and at the same time a pressure on the relative friction surfaces of the respective friction surfaces 8, 8 'is generated.

The motion arrest between the pinion and the carrier depends in particular on the angle and diameter of the conical friction surfaces.

As shown in FIG. 8, during the interlocking operation of the automobile internal combustion engine by the electric motor of the starter, the carrier 24 and the shaft (after being generated by the starter at the level of the output shaft 12 having the carrier 24). 12) The torque Cd deformed by the device with the helical groove intervening in between creates an axial force Fa.

The force Fa is dispersed at the level of the conical friction surfaces to produce a vertical contact force Fc. The vertical contact force Fc forms a tangential force Ft at the conical friction surface according to the friction coefficient between the friction surfaces. The value of the tangential force Ft, increased through the average contact radius of the conical friction surface, defines the torque Ce transmitted through the conical clutch 7.

Ce> Cd must always be satisfied for the pinion to work normally without slipping.

All of this depends on how it is applied. This is because the proportional coefficient between Cd and Fa not only depends on the inclination angle of the groove 9 and the average radius of the groove, but also on the sliding coefficient between the output shaft 12 and the carrier.

The proportional coefficient between Fa and Fc depends on the angle of the cone between the two conical friction surfaces.

The Ft value is related to the Fc value and the friction coefficient fc appearing between the materials of the two conical friction surfaces of the clutch 7. In order to avoid disturbance, the tangential relationship (a)> fc must be guaranteed. Where a is the value of the half angle of the vertex of the contact cone between the conical friction surfaces, and fc represents the coefficient of friction.

All of the above values are calculated according to previously known structural formulas and are values depending on the application.

To use these formulas, the coefficient of friction between the grooves of the shaft and the carrier, the average radius of these grooves, the angle of the cone of the friction surfaces 8, 8 ', and the friction coefficients of the friction surfaces must be applied. All of these influence the choice of materials used for the carrier, side and pinion.

When the automotive engine is started, the pinion 14 rotates faster than the output shaft 12. This disassembles the starter drive assembly on the shaft 12. The previously transmitted axial drag disappears, leaving only the weak residual torque resulting from the elastic devices 10, which is transmitted to the starter's electric motor. During this short ultrafast process, the clutch acts like a freewheeling device, making the relevant movement between the friction surfaces 8, 8 '. Therefore, the average contact diameter between the two friction surfaces 8, 8 'is equal to the friction diameter in the ultrafast process.

In contrast to freewheels with rollers where radial deformation can occur, freewheels with conical clutches do not include inherent shock absorbers. Thus, when the pinion 14 comes into contact with the stop element 30, it is subjected to a greater axial impact than in a starter drive assembly with a freewheel with a roller. The shock absorber 40 according to the invention described above according to one of the possible variant embodiments has its advantages, as shown in FIG. 10, by being placed in an automobile starter comprising a drive assembly equipped with a conical clutch. Will be able to exercise. This combination reduces mechanical stress, resulting in a more economical, lighter, quieter, and more robust starter.

Claims (15)

An electric motor 10 with one rotor coupled to the output shaft 12, A pinion 14 for interlocking the toothed ring gear 15 of the flywheel of the combustion engine, the pinion having an output shaft 12 between a stationary position that is separated from the ring gear 15 and an operating position that engages the ring gear. A starter drive assembly 18 adapted to axially slide on A freewheel transmission device 20 connected to the control lever 16 for horizontal movement of the starter drive assembly 18, A shearing surface disposed on the output shaft 12 to limit the movement of the starter drive assembly 18 in the operating position and to mitigate the impact that occurs when the pinion 14 engages with the ring gear ( A stop element 30 consisting of an elastic element 40 with a 52 and a metal ring 31, The resilient element (40) is an electric starter for a combustion engine of a vehicle, characterized in that it comprises means for obtaining sufficient rigidity to withstand the transfer pressure. The method of claim 1, An electric starter, characterized in that the front ends (52) of the resilient element (40) are formed with protrusions (42) such that a progressively strong braking force can be applied to the pinion (14). The method according to claim 1 or 2, The resilient element 40 is an electric starter, characterized in that it is formed of a rubber stud material which gradually deforms under the driving force of the pinion (14). The method of claim 1, The shock absorber (40) is provided with a corresponding element (48) against which the pinion (14) abuts on its front face (52). The method of claim 4, wherein The corresponding element (48) consists of a machined steel washer. The method of claim 1, The ring (31) of the stop element (30) is characterized in that it is provided with a projection (44) towards the pinion (14) to limit the compression of the cushioning end. The method of claim 1, wherein The resilient element (40) has an electric starter, characterized in that it has an annular shape having a rectangular cross section fixed to the ring (31). An electric motor 10 with one rotor coupled to the output shaft 12, A pinion 14 for interlocking the toothed ring gear 15 of the flywheel of the combustion engine, the pinion having an output shaft 12 between a stationary position that is separated from the ring gear 15 and an operating position that engages the ring gear. A starter drive assembly 18 adapted to axially slide on A freewheel transmission device 20 connected to the control lever 16 for horizontal movement of the starter drive assembly 18, A stop element 30 disposed on the output shaft 12 to limit the movement of the starter drive assembly 18 in the operating position, The stop element 30 consists of a metal ring 31 and an elastic element 40 having a shear surface 52 for mitigating the impact that occurs when the pinion 14 engages with the ring gear, The electric starter, characterized in that the freewheel transmission device (20) has a conical clutch (7). The method of claim 8, The resilient element (40) comprises means for obtaining sufficient rigidity to withstand the transfer pressure. The method according to claim 8 or 9, An electric starter, characterized in that the front ends (52) of the resilient element (40) are formed with protrusions (42) such that a progressively strong braking force can be applied to the pinion (14). The method of claim 8, The ring (31) of the stop element (30) is characterized in that it is provided with a projection (44) towards the pinion (14) to limit the compression of the cushioning end. The method according to any one of claims 8 to 10, The resilient element 40 is an electric starter, characterized in that it is formed of a rubber stud material which gradually deforms under the driving force of the pinion (14). The method of claim 8, The shock absorber (40) is provided with a corresponding element (48) against which the pinion (14) abuts on its front face (52). The method of claim 13, The corresponding element (48) consists of a machined steel washer. The method of claim 8, The resilient element (40) has an electric starter, characterized in that it has an annular shape having a rectangular cross section fixed to the ring (31).