KR20020086660A - Motor vehicle starter comprising a starter drive pinion with helical toothing - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a starter for an automobile, wherein the starter (10) starts when the starter driver switches from a stop position to an operating position where the pinion (54) of the starter driver (32) engages with the flywheel ring gear of the car heat engine. It is characterized in that the pinion 54 of the starter drive 32 moves in the axial direction at the front part 20 of the drive shaft of the drive shaft.

Description

Automotive starter with drive pinion with spiral teeth {MOTOR VEHICLE STARTER COMPRISING A STARTER DRIVE PINION WITH HELICAL TOOTHING}

At start-up, before the initial explosion stroke, the heat engine exhibits high resistance torque during the starter interlock process, especially when the engine is cold.

The torque generated by the starter is decelerated by the engagement of the pinion which rotates with the starter shaft and the crown connected with the crank shaft of the heat engine.

When the heat engine is started, the pinion is pulled out of the crown, and vice versa, the pinion engages the crown at high rotational speeds causing a lot of noise and excessive wear.

The pinion can slide in the axial direction along the starter axis since the longitudinal grooves ensure the transmission of the engine torque by means of a smashed shaft. The longitudinal grooved shaft is also connected to a case equipped with a "freewheel" system with rollers, which allows the armature of the starter electric motor to rise at an over-rotating speed during an intermediate operation during which the heat engine will rise to normal speed. To avoid.

The pinion assembly formed by the free wheel and the longitudinal groove with the smashed axis constitutes the drive of the starter.

The axial movement of the drive is caused by the axial movement of the electromagnetic starting portion of the starter using the lever. The axial movement of the starter electromagnetic starter also ensures that the starter is under voltage.

The start process is as follows.

-Voltage on the starter by contact key;

-Meshing of crown and pinion and energizing the starter electric motor;

-Rotational linkage of the crown by the starter and start of the heat engine;

-Freewheel operation of the drive due to the crown of the heat engine having a speed much faster than the speed produced by the starter;

-Contact key loosening, return to the starting position of the starting section and departure from the pinion of the crown.

When the pinion moves axially within the crown to engage the crown and pinion with each other, the relative position of the teeth of the pinion and crown may not correspond. In this case it can be said that the tooth is opposite to the tooth, in which the pinion cannot end its axial movement without the teeth being placed in the correct position through the rotational movement.

This rotation can be caused by energizing the starter's electric motor, ie by putting the armature in rotation. This is because the lever causing the axial movement of the drive is connected to the shaft of the starter by a spring. When placed in the "tooth to tooth" state, the spring allows the starter shaft to complete its motion and is compressed with the starter electric motor under voltage.

Thus, in this case, the teeth of the pinion find the correct position with respect to the crown (since the armature starts to rotate), and the pinion engages axially within the crown, transmitting electromagnetic torque before reaching the end of its axial movement.

In the position where the pinion and crown teeth are in contact, the frictional resistance will very quickly be greater than the axial thrust of the lever which blocks the axial movement of the pinion.

In this situation, the propulsion of the teeth is reduced, which can lead to excessive wear conditions that can cause the teeth to be pushed out of the crown, referred to as the "phrase barn" phenomenon.

In the conventional starter, the above-described phenomenon is prevented by using the spiral grooves in which the starter shaft is slid to the driving unit and connected in rotation.

Since the inclined direction of the spiral grooves is limited by the rotational direction, the engine torque generated by the electromagnetic is axially driven on the drive, i.e., the pinion which induces the axial movement of the engine torque and maintains the engine torque in the crown. It will create a driving force.

The axial thrust corresponds to the force F _ac , see FIG. 2, because the forces in the helical groove and pinion are disassembled.

However, this conventional starter has the following disadvantages. In other words, during the intermediate process occurring after putting the starter under voltage, the pinion no longer performs axial movement, nor does the rotational movement produced by the spiral grooves. Inertia rotation of the drive unit increases the resistance to lower the axial motion of the pinion, and increases the gap with the movement of the starter moving shaft. This increases the risk that the electromagnetic will rotate before the pinion and crown are fully engaged.

On the other hand, in order to reduce cost and operating time, the engagement of the pinion with the crown is realized with a straight tooth. In other words, the side surfaces of the tooth are placed parallel to the axis of rotation of the member placed in a bad position. Functional clearances should be provided to avoid machine shutdown and wear. This prevents the engagement from continuing and as a result the starter generates a lot of noise during the course of the start-up, further increasing the wear on the side teeth.

The present invention relates to a starter including a drive unit moving axially from the front of the drive shaft of the starter when the pinion of the starter drive unit is shifted from the stop position to an operating position where the pinion of the starter drive unit is engaged with the flywheel ring gear of the automobile heat engine. It is about.

1 is a partial axial cross-sectional view of a typical starter.

FIG. 2 is an enlarged perspective view of the starter driver of FIG. 1.

3 is a view similar to FIG. 2 and illustrating a driving unit according to an exemplary embodiment of the present invention.

In order to overcome these disadvantages, the present invention proposes a starter characterized in that the pinion of the drive unit has a spiral tooth.

Another feature of the present invention is that the toothed spiral direction of the drive pinion is adopted as the direction for transmitting the axial thrust force forward to the pinion to transmit the torque generated by the electric motor of the starter to the crown.

According to the invention, the axial thrust forces acting on the drive, ie above the pinion of the drive, are all transmitted in the same direction in the same direction.

Looking at other features of the present invention,

The conduction ratio resulting from the engagement of the spiral pinion and the crown is equal to or greater than 1,5.

The drive part comprises one rear axle which is interlocked with the motor shaft via the helical groove, the helical direction of which is opposite to the helical direction of the drive pinion.

The drive part comprises one rear axle which is interlocked with the motor shaft via a straight groove.

In the following, it will be described by adopting the left side in the front direction and the right side in the rear direction according to FIG. 1.

1 illustrates a typical automotive starter 10.

This starter contains a starter chassis. The main part of the chassis is the projection 12 of the starter located in the front, and has a bulging shape to fix the starter to the automobile fixing part and to make each linkage (not shown). The electromagnetic starting portion 14 and the electric motor 16 with a case (not shown) are arranged at the rear of the projection 12.

The electric motor 16 is placed parallel to the electromagnetic starter 14, in particular including one case 18 and one armature shaft. The front part of the armature shaft allows direct or indirect indirect transmission of rotational movement to the outlet shaft 20 via, for example, a reduction gear with an epicycloid train. The free front end 22 of the outlet shaft enters the bearing 24 located in the projection 12 of the starter.

The outlet shaft 20 is a motor shaft.

In FIG. 1, the armature shaft is distinguished from the outlet shaft 20. As is better seen in French patent FR-A-2 795 884, which represents an electromagnetic starting part and an electric motor, the base plate (not shown) carries the tooth crown of the plastic epicycloid train in order to reduce noise. The plate also carries a link support made of plastic for the control lever 34. For a more detailed description of the structure and function of the electromagnetic starting section, reference may be made to the above document.

In some embodiments, the armature shaft and the outlet shaft 20 can be confused. Therefore, epicycloid trains are not necessary.

The electromagnetic starting portion 14 and the electric motor 16 are fixed to the projection 12 of the starter by means of fixed transverse screws 26 and 28.

The drive part 32 is the groove of the outlet motor shaft 20 when the drive part 32 is switched from the rear stop position (reversed position) shown in FIG. It moves axially on this crushed intermediate part 31. The drive part 32 includes a front drive part 30 having a pinion 54 made of abrasive steel or smelted steel.

The axial movement of the front drive section 30 is realized by the control lever 34 which makes axial rotation, and the control of the control lever is realized by the electromagnetic starting section 14.

Since the structure of the electromagnetic starter 14 is already known, the structure thereof will not be described further below. As a function, the electromagnetic starting unit not only transmits the electric energy generated by the electric motor 16 through the system 36 called a starter, but also controls the lever 34 through the outlet device 38 in the form of a rod. Causes axial center rotation of the. The front free extreme end of the outlet device includes a transverse connecting pin 40 which is introduced into the groove formed on the upper end of the control lever 34.

In the case where "toothed teeth are opposite" (crown teeth 58 and pinion teeth 54 abut), the outlet device 38 is connected to the moving shaft of the starting portion by a spring. The action of the spring causes the moving shaft to stop motion, which is a phenomenon occurring for contact generation of the starter system 36 and power transmission to the electric motor 16.

The control lever 34 is preferably made of plastic in order to reduce noise, and in FIG. 1 the control lever is around a vertical axis of wheel alignment which includes the axis of rotation of the armature axis of the electric motor 16 and the axis of the electromagnetic starter 14. It is mounted to rotate.

The wheel alignment shaft is supported by a support connected to the base plate, which is made of plastic material to reduce noise.

The lower part 42 of the control lever 34 is in the form of a bracket which works together with the control bearing 44 of the drive part 32, and is supported by a fixing plate (without reference numeral) connected to the rear extreme part of the drive part 32. It is made to be.

As shown in FIG. 2, the drive part 32 includes an inlet rearward device 46 in the form of a shaft internally grooved by a helical groove 48. These helical grooves interlock the outlet device via a freewheel 50 with a roller 52, the forward extreme of which is also the drive pinion 54 with straight teeth 56. The rear device 46 is an interlock device and is connected to the case of the free wheel. The device 46 bears on this fixing plate while connected to the fixing plate mentioned above. A control bearing is also connected to this device 46. The pinion 54 of the drive is used to work with the complementary teeth of the crown 58 (illustrated in FIG. 1) which interlocks as it rotates to the automotive heat engine crankshaft with starter 12. The roller is operated between the case of the freewheel 50 and the rear extension in the form of a connecting barrel of the pinion 54. Of course, the starter protrusion 12 has an opening for the operation of the crown 58 teeth.

The pinion is in contact with the strut at the forward position, which is the engaged position, and the material of the strut is preferably a rubber material.

As shown in FIG. 3 in accordance with the invention, the teeth 56 of the pinion 54 and the complement teeth of the crown 58 are helical teeth.

By doing so, the noise is reduced, and as a result the starter is quieter.

The present invention relates to the use of a helical tooth for the engagement of pinion 54 and crown 58. The inclination direction of the helical teeth is selected according to the rotation direction of the motor. As a result, the pinion 54 "pulls" the crown 58 in the axial direction by the torque supplied by the starter 12 motor 16.

In other words :

: Motor torque supplied by the starter 12

: Normal module of pinion (54) tooth

: Number of teeth (56) of pinion (54)

: Indentation of the tooth of the pinion

: Pressure angle of pinion tooth

: Initial diameter of pinion

: Coefficient of friction of teeth

: Normal module of groove

: Number of teeth in the groove

: Pressure angle of groove

: Helix angle of groove

: Initial diameter of pinion

: Friction coefficient of groove

As in FIG. 2, in FIG. 3, the force is decomposed at the groove 48 and the pinion 54. Axial force F _ac is present in the pinion portion. The axial force is opposed to the axial force F _fp in FIG. 2 and acts in the same direction as the axial force F _ac of the groove portion.

More precisely, the axial thrust is imposed on the pinion due to the torque of the motor supplied by the starter:

Thrust F of Lever_ㅣAdded to The axial force must be greater than the friction occurring in the grooves and teeth. This condition can be formulated as:

Comparing the structure with the straight tooth (β _p = 0) and the structure with the helical tooth, it is easy to see that the axial propulsion increases much faster than friction.

For example,

grooved axis Z _c = 9; m _c = 1.5; α _c = 30 °; β _c = 25 ° with a force equal to f _p = 0.19; f _c = 0.16

With pinions Z _p = 9; m _p = 2.203; α _p = 20 ° with straight teeth, F _a -F _f = 120 N is obtained for _a motor torque of 10 Nm.

On the other hand, a spiral-pinion Z _p = 9 with a _{tooth; m p = 2; α p} = 18.283 °; With β _p = 24.806 ° is F -F _{f a} = 545N is obtained in the motor torque of 10Nm (in the drawing The teeth perpendicular to the axis of rotation are the same as the straight teeth described above).

In addition, to achieve the same result F _a -F _f = 120N, a groove with a groove of β _c = 6.87 ° would have to have a fine axis, thereby improving the starter's function.

As for the noise of this device, we saw earlier that the noise depends on the persistence of the pinion linkage.

The above concept is measured using the conduction ratio ε _α , and the larger this coefficient, the better the interlocking persistence.

Clearly, helical teeth are more efficient when comparing straight and helical teeth. This is because the conduction ratio of the helical tooth is increased by the interlocking ratio which varies with the tooth width and the spiral angle, unlike the conduction ratio of the straight tooth.

For this reason, the interlocking ratio for the 9 mn tooth width in this embodiment is 0,6. The conduction ratio by a straight pinion with nine teeth is generally between 1,00 and 1,15. On the other hand, the conduction ratio by the helical pinion is comprised between 1,6 and 1,75, which shows the efficiency of the helical tooth.

Therefore, the starter according to the present invention can not only reduce the noise, but also can reduce the size of the magnetic circuit and the electromagnetic starter coil, and can realize the "contrast with the teeth of the tooth", and the outlet device 38 of the starter 38 It is also possible to reduce the force of the spring acting between) and the moving shaft. This results in reduced wear.

The above result is due to the fact that the axial forces acting on the driving part 32, that is, F _ac and F _ap are mutually coupled and act toward the front part.

Of course, the present invention is not limited to the above-described embodiment.

For example, the freewheel can be replaced with a conical clutch to reduce its cost. That is, it includes a first friction surface of a truncated cone connected to the pinion and a second friction surface of a truncated cone connected to the inlet device and complementarily connected to the first surface.

In another embodiment, one of the surfaces of the conical clutch may be composed of a friction reinforcement.

For further details see French patent FR01 08607 filed June 29, 2001.

In all cases, a detachable linkage may be used with the grooved shaft 46 and pinion 54.

The pinion may be supplemented in the form of a tether on its extension which constitutes the track for the roller of the freewheel or for the support element of the first friction surface of the truncated cone of the conical clutch.

For example, the pinion can be connected to its extension by welding or inserting as described in French patent FR00 13981.

As another example, the connection can be realized using a metal reinforcement frame as described in French patent FR01 08607 cited above.

As yet another embodiment, the material of the pinion can be selected as a less noisy melted material or any other material that can match well with the material of crown 58 in particular in terms of noise reduction.

In the embodiment of the present invention, the inlet device 46 constituting the interlock is also composed of molten material.

In addition, a combination of the various embodiments described above is possible.

It is of course also possible to install a shock absorber inside the drive to further reduce noise, as described in French patent FR01 10911 filed on 2001.8.17.

The shock absorber may be placed between the case of the freewheel and the inlet device in the form of a slotted shaft, for example with a cushioning element such as a spring sandwiched between synthetic rubber or a projection.

In the present invention, the rear shaft 46 is in the shape of a connecting cylinder. In another embodiment, the shaft 46 exhibits a cylindrical shape at the bracket 42 portion of the lever 34 and another shape at other portions. In another embodiment, the tooth and the tooth opposite spring act between the bearing 44 and the annular stationary plate. The stationary plate is then moved relative to the cylindrical shaft 46 because it is in contact with the lever portion 42, for example representing a cylindrical pinion supplemented with an annular groove of the stationary plate.

Claims (6)

When the pinion 54 of the drive unit 32 switches from the stop position to the operating position, which is a position to engage with the toothed crown 58 of the automotive heat engine flywheel, at the front 20 of the motor shaft of the starter 10. In the vehicle starter (10) having a drive unit (32) which moves in the axial direction and includes a rear shaft (46) interlocking with the motor shaft (20) via a groove, Starter for a vehicle, characterized in that the pinion (54) of the drive section (32) is provided with a helical tooth (56). The method according to claim 1, wherein when the torque generated by the starter's electric motor is transmitted to the toothed crown (58), the helical direction of the drive pinion (54) is a direction in which the pinion transmits the axial thrust force forward. Automotive starter, characterized in that is adopted. 2. The starter of claim 1, wherein the conduction ratio generated by the meshing of the spiral pinion and the crown is 1,5 or more. The rear shaft 46 is interlocked with the motor shaft 20 via the helical groove 48, the spiral direction of the groove is the drive unit 32, the pinion 54. Automotive starter, characterized in that the reverse to the spiral direction. 4. The starter of claim 1, wherein the rear shaft (46) rotates in coordination with the motor shaft (20) via straight grooves. 2. The starter for automobile according to claim 1, wherein the pinion (54) is made of a molten material.