EP1108139A1

EP1108139A1 - Method for gradually driving a motor vehicle starter switch

Info

Publication number: EP1108139A1
Application number: EP00946032A
Authority: EP
Inventors: Gérard Vilou; Régis MAILLET
Original assignee: Valeo Equipements Electriques Moteur SAS
Current assignee: Valeo Equipements Electriques Moteur SAS
Priority date: 1999-06-30
Filing date: 2000-06-28
Publication date: 2001-06-20
Anticipated expiration: 2020-06-28
Also published as: KR20010072887A; BR0006834A; JP4854894B2; WO2001002722A1; FR2795883B1; KR100687975B1; BR0006834B1; DE60010416T2; JP2003503638A; US6516767B1; DE60010416D1; FR2795883A1; EP1108139B1

Abstract

The invention concerns a method for powering a driving coil of a mobile core of a motor vehicle electrical starter switch, which consists in varying the efficient current in the coil while the core is moving towards its contacting position, and in adopting during said displacement: a first driving phase with sufficiently high efficient current to move the core; then a second driving phase with lower efficient current, whereby after a specific or predetermined time the efficient intensity is continuously increased.

Description

Method for gradually driving a motor starter switch

The present invention relates to methods and devices for controlling motor vehicle starters, and more specifically to methods and devices for driving the contactor core of these starters.

As illustrated in FIG. 1, a motor vehicle starter conventionally comprises a contactor 2 as well as an electric motor M, the output shaft of which carries a pinion 1. The pinion 1 is intended to cooperate with the gear of the starter ring C of the heat engine. It is sliding on the shaft of the motor M between a position where it is disengaged relative to said starter ring and a position where it meshes with the latter. The contactor 2 extends parallel to the electric motor M above the latter and comprises a coil 2a and a plunger core 2b.

It ensures the supply of the electric motor M by displacement of a movable contact 3 between an open position and a closed position, said contact 3 being pushed by said plunger core 2b movable axially relative to the electric motor M when the winding 2a is activated.

The contactor 2 also controls the movement of the pinion 1. Its plunger core 2b is therefore connected to the pinion 1 by mechanical means referenced by 4 as a whole. These mechanical means comprise a fork coupled at its upper end to the plunger core 2b and at its lower end with a launcher to which the pinion 1 belongs.

This launcher comprises a freewheel interposed axially between a hub and the pinion 1. The hub is internally provided with helical splines engaged in complementary manner with external helical teeth carried locally by the output shaft of the electric motor M. The fork is pivotally mounted between its two ends on a casing internally containing the mechanical means 4 and carrying the motor M and the contactor 2. The starter with its pinion 1 is driven in a helical movement when it is moved by the fork to engage the starter ring.

This is achieved by supplying the winding 2a following an actuation of the ignition key which makes it possible to set in motion the plunger core 2b then drawn towards a fixed core mounted at the end of a support for the coil 2a. This support has a U-shaped section for housing the winding 2a and therefore has a bottom constituting a pad 2C. The core 2b is therefore intended to move between a rest position and a contact position in which it rests on the fixed core, this closed position of the magnetic circuit taking place after closing of the movable contact 3 and therefore of the electrical circuit. . The mechanical means also include a return spring mounted around the core 2b to return the latter to the rest position, a cut-off spring associated with the movable contact 3 to return the latter to the open position and a spring 5, called a spring. teeth against teeth, housed inside the core 2b and engaged with a first rod connected by an axis to the upper end of the fork for coupling it to the core 2b. This spring 5 has a greater stiffness than the return spring.

The fork is therefore inserted at its upper end between the core 2b and the axis. The first rod, mounted inside a blind hole in the core 2b, is intended after a determined stroke to come into engagement with a second rod secured to the movable contact 3 and slidably mounted inside the fixed core. In the closed position, the contact 3 cooperates with a fixed contact, in the form of studs connected respectively to the positive terminal of the battery and to the electric motor M, thus enabling the electric motor to be supplied. The studs are integral with the closure cover of the contactor made of insulating material.

All of these elements are shown in Figure 1 and have not been referenced for simplicity. The pinion 1 can therefore come into engagement with the crown C, that is to say come into engagement position with the crown C, before the movable contact is closed.

Most often the pinion 1 comes axially into abutment contact with teeth of the crown C before penetrating therein.

Thus the mechanical means 4 include in particular a spring 5 which is mechanically interposed between the plunger core 2b and the pinion 1 and which allows the plunger core 2b to continue its travel to ensure, before contact with the fixed core, the positioning of closing of the movable contact, even if the pinion 1 is blocked in abutment against the teeth of the crown of the heat engine, in a position where it does not mesh with this crown.

However, given the speed of movement of the movable core 2b and the elasticity of the mechanical connecting means 4, due in particular to the presence of the spring 5, there may be significant phase shifts between the closing of the contact 3 and the translation of the pinion 1. Particularly at low temperature, one can observe a rotation of the electric motor M and therefore of the pinion 1 before the latter has had time to penetrate the crown. The electric motor M being supplied at full voltage, the speed of the pinion 1 increases very quickly, thus preventing the pinion from engaging with the crown. It follows a rapid destruction of the crown and the pinion.

In document FR-A-2 679 717, it has been proposed to overcome this drawback of supplying the contactor with a variable pulsed current. Referring to Figure 2, in this type of arrangement, a coil B controls both a contactor K and the advancement of a pinion not shown. The coil B is supplied via a transistor T in pulse mode, of the pulse width modulation (PWM) type, in French, the transistor being controlled by a microcontroller 10 .

A cyclic ratio of the pulses is gradually increased to obtain an effective current in the coil which increases progressively. We wish, in this way, that the mobile core begins to move with a minimum magnetic attraction force and therefore a minimum acceleration, so as to avoid a phase shift between the movement of the core and that of the pinion previously described.

This process also aims to reduce the speed of impact of the pinion against the crown to reduce the frontal wear of the latter.

However, it does not prevent sudden displacement of the core from its rest position to its activation position.

To further reduce this impact speed, in document US-A-4 418 289, in accordance with the preamble of claim 1, a method has been proposed for supplying a drive coil with a moving contactor core. electric starter of a motor vehicle, in which the effective current in the coil is varied during the displacement of the core towards its contacting position, and in which one adopts during this displacement: - a first phase of effective current drive high enough to set the nucleus in motion, then,

- a second phase of lower effective current drive. This document also proposes a device for controlling the supply of a drive coil of a movable core of a motor starter contactor, provided for varying the effective current in the coil during the displacement of the core towards its contact position, in which it is intended to implement during this displacement:

- a first drive phase with an effective current sufficient to set the nucleus in motion, then,

- a second phase of lower effective current drive. In practice, it is planned in the second phase to power the electric motor to make it rotate at reduced speed thanks to an additional disc, additional contacts and an additional resistor integrated into the contactor. This second phase ends when the movable contact closes, which then cooperates with the fixed contact to supply the electric motor at full power. This solution is not entirely satisfactory because it complicates the production of the contactor.

In addition it is not entirely reliable because for example the launcher, and therefore the pinion can be blocked. The object of the present invention is to overcome these drawbacks in a simple and economical manner.

According to the invention a method of the above-mentioned type is characterized in that during the second phase, when the movable core is not in the contacting position, a continuous increase is implemented after a determined or predetermined time effective intensity.

According to the invention a device of the above-mentioned type is characterized in that during the second phase, provision is made to implement, after a determined or predetermined time, a continuous increase in the effective intensity. Thanks to the invention the contactor has a simple shape and a sudden displacement of the core, from its rest position to its activation position, is avoided.

Indeed, the effective intensity in the first interval of the second phase is lower than that of the start of the solution of document FR-A-2 679 717 since the core has already taken off. This reduces noise and the solution is safe.

Indeed, after a predetermined or predetermined time, the progressive increase in the effective intensity makes it possible, on the one hand, to gradually compress the spring, teeth against teeth 5, and, on the other hand, the closing of the contactor to supply the electric motor in the accidental case where the contactor could not have been closed before.

Thus in the accidental case where abnormally high friction forces take place in the contactor, in the mechanical means or at the level of the shaft of the electric motor, the contactor is closed beyond a predetermined or determined time.

Such cases can occur following particular climatic conditions, seizures, especially when the vehicle has been immobilized for a long time. Dust, dirt can settle on the level of the fork and the shaft of the electric motor and thus hinder the movement of the pinion.

Thanks to the invention, it is nevertheless possible to move the launcher and its pinion. In addition, the pinion comes into abutment contact with the starter ring, either before increasing the intensity, or after increasing the intensity and before closing the movable contact, so that one sets in motion the electric motor from a zero speed in this stop contact position, which facilitates the penetration of the pinion into the crown while therefore reducing wear.

The solution according to the invention is therefore reliable and makes it possible to increase the life of the starter thanks in particular to a reduction in wear.

In addition, energy consumption and noise are reduced. The solution is economical because the contactor can have only one winding.

Thanks to the invention, measurements can be made during the first phase. This first phase can be broken down into two intervals, namely a first interval with high effective current followed by a second interval with lower current than that of the second phase. Preferably this second interval is carried out at zero current for better accuracy of the measurement.

So we can measure the battery voltage during the first phase. During this first phase the core can take off with a shorter stroke, the intensity during the first interval of this first phase being close to the intensity necessary to make the core take off and being carried out with a shorter time.

If problems arise subsequently, non-separation of the core, non-closing of the contactor for example, thanks to the continuous increase in the effective intensity according to the invention, these problems will be solved. The limited separation of the core makes it possible to further reduce the impacts of sudden displacements, and to reduce energy consumption.

Thanks to the invention the winding has a double function because, after a third interval of the second phase, during which it increases the intensity of the effective current, after rotation of the electric motor, it allows the mobile contact to be closed during a third phase.

It will be appreciated that the electric motor only turns after the pinion comes into abutment with the crown, so that the pinion can penetrate more easily into the crown and that wear is reduced.

Thanks to the invention in the first phase, one can be on the verge of detachment of the core so that the movement of the latter is even less brutal.

The time is determined as a function of abnormal values which occur in the event of the mobile contact not being closed.

The time is determined as a function, for example, of the battery voltage or the winding temperature.

The time is easily predetermined so that the continuous increase in intensity occurs only when necessary, that is to say so that this time is as short as possible and includes the majority of normal cases of operation .

Other characteristics, objects and advantages of the invention will appear on reading the detailed description which follows, given with reference to the appended figures, in which: - Figure 1 shows a motor vehicle starter in accordance with the state of the technique ;

- Figure 2 shows a supply arrangement of a starter switch according to the state of the art;

- Figure 3 is a plot showing the evolution of a duty cycle of the supply voltage of a contactor coil, according to the invention;

- Figure 4 is a partial view similar to Figure 3 for another embodiment.

As illustrated in FIG. 1, the plunger core 2b is placed in the bearing 2C in a sliding relationship which is modulated by the presence of a lubricant ensuring a sealing and braking role. The core 2b is therefore a mobile core.

The core has, in its rest position, a force of adhesion to the pad Fa which opposes its setting in motion. When the nucleus is set in motion, this force Fa disappears in favor of a friction force Ff, which is much lower than Fa (of the order of 20 to 40% lower).

The presence of the lubricant does not eliminate these forces. On the contrary, by a gumming effect of the lubricant, it further accentuates the fact that the adhesion force Fa exceeds the friction force Ff. The movable core 2b remains at rest as long as the coil 2a does not exert a motive force of attraction Fm which is greater than Fa.

During the setting in motion of the core 2b, the effective intensity in the coil 2a is gradually increased. The retaining forces of the core suddenly decrease (from Fa to Ff) when the core is set in motion, while the attractive force Fm already reaches a high value at the start of the core. This difference between Fm and Ff therefore induces at the time of unlocking of the core an abrupt acceleration of the mobile core so that progressive feeding therefore does not produce the desired effects.

Here, a device for supplying the coil 2a is used, the mounting of which remains similar to that shown in FIG. 1, and in which a supply of the coil 2a is again adopted according to a niche voltage of the PWM type.

However, the duty cycle is varied during the displacement of the core according to the evolution represented in FIG. 3 and this after a predetermined or determined time.

On this plot, we have indicated on the abscissa successive instants during the displacement of the nucleus, from its initial rest position (instant T ₀ ) to a final position ("nucleus calling period") where it is in abutment against the fixed core and where it provides contact, the movable contact 3 then being closed.

The call period of the kernel is broken down into two main phases, the second of which is broken down into three sub-phases. We will now describe these two main phases.

During the first phase going from instant t ₀ to instant ti, we adopt a duty cycle R1, close to or equal to 100% (the duty cycle is the ratio between the conduction time of transistor Ti and the total time of a cycle). During this phase, a high effective intensity crosses the coil 2a and the core 2b is subjected to an attractive force Fm sufficient to detach it from its rest position and set it in motion. This phase is brief, here of the order of 2 to 10 ms, in order to produce a high attraction force on the nucleus only for the purpose of detaching the latter.

The second phase takes place between time ti and time t ₃ . In a first interval of this second phase, the transistor Ti controls the contactor according to a duty cycle having an R2 value substantially equal to 50%, so that the effective current in the coil 2a is significantly reduced compared to that obtained during the first phase, just sufficient to overcome the residual friction forces Ff after takeoff from the core 2b. During this interval which lasts approximately 30 to 60 ms, the core 2b therefore continues its movement until the contactor closes, without brutality and without excessive speed. During this first interval of the second phase, in the general case, an abutment contact is obtained between the pinion 1 and the starting ring gear between the times t1 and t2.

More specifically, the microcontroller 10 is connected by one of its inputs to a temperature sensor placed inside the contactor 2a in the vicinity of the winding 2b and is also connected by a second input to the supply terminals of the starter.

The microcontroller 10 takes from these two inputs signals representative of the temperature T of the contactor therefore of the coil 2a and of the supply voltage U at the input of the starter.

The starter supply voltage is variable depending on the state of charge of the vehicle battery and the temperature. Indeed, the temperature of the coil 2a directly conditions its resistance. However, the average current obtained for a given duty cycle, depends directly on the voltage available at the terminals of the starter - therefore at the terminals of the battery - and on the resistance of the coil 2a.

Thus, the microcontroller 10 includes a memory in which a digital table is recorded, corresponding for an intensity effective efficiency desired, the duty cycle R2 to be adopted as a function of the starter supply voltage and the temperature of the coil. In practice, R2 is of the order of 0.4 to 0.6 at a temperature of 20 °.

The effective intensity is substantially constant in this first interval.

Thus, the microcontroller 10 automatically adopts a duty cycle R2 as a function of the supply voltage at the terminals of the starter and of the resistance of the winding (itself dependent on the temperature). The measurements of the voltage U and of the temperature T are advantageously carried out before the implementation of the first phase described above, when the starter is activated.

In a second interval of the second phase, which elapses between the instant t ₂ and the instant t ₃ , and according to the invention after a predetermined time or in a determined variant, the microcontroller 10 implements an increase continuous and progressive of the cyclic ratio, going from the R2 ratio to find the R1 ratio or alternatively a ratio greater than R1. This interval has a duration of approximately 20 to 50 ms and makes it possible to ensure, by the gradual increase in the effective intensity, the closing of the contactor, in an accidental case where the contactor could not have been closed between t1 and t2. Such an accidental case can occur in particular if abnormally high friction forces take place in the contactor, in the mechanical means 4 and at the level of the motor shaft M. These abnormal forces are due for example to climatic phenomena, expansion, seizure, the presence of dirt impurities and all other stains, in particular at the splines of the shaft of the electric motor and the joints of the fork.

During this second interval, the teeth against teeth spring 5 is compressed to allow the plunger core 2b to actuate the movable contact 3 to supply the electric motor and rotate its shaft in order to ensure penetration of the pinion in the crown and therefore a meshing of the pinion with the crown.

Of course in the case where the movable contact is closed between times t1 and t2, pinion meshing with the crown 3, there is no need to carry out the continuous increase in intensity because the meshing is carried out before a predetermined time depending on the applications. In 90% of cases, the mobile contact is closed before this predetermined time as short as possible to include normal operations. As a variant, this time is determined for example as a function of the battery voltage or of the temperature of the coil 2a, these quantities being influenced by the non-closing of the movable contact generating abnormal values.

In all cases in an additional interval elapsing in FIG. 3 between the instant t3 and an instant t4, the duty cycle is maintained at R1 or at a value greater than R1 for approximately 5 to 30 ms. This phase with a high duty cycle begins when the movable contact 3 closes and keeps the core 2b in its contacting position (movable contact 3 closed) with a high attraction force which prevents rebounds of the movable core 2b against a stop usually formed by another nucleus, fix that one. This third interval t3, t4 lasts long enough to be able to absorb the current peaks due to the starting of the heat engine by the electric motor M, which according to a characteristic of the invention is not controlled. According to one characteristic, it is therefore only after abutment of the crown with the pinion that the increase in the duty cycle is carried out.

After the third interval, a cyclic ratio R3 is adopted in a third phase at the terminals of the winding resistance 2a to maintain the movable contact in the closed position.

The rms current is lower in this third phase than in the other two phases.

As will be understood and it emerges from the description, a single coil 2a is necessary and the microcontroller can be mounted on a support, such as a card, in the starter, more precisely be mounted at vicinity of the winding 2a in the space between the movable contact 3 and the cover (not referenced in FIG. 1) carrying the fixed contacts. Thanks to the invention and to the pulse width modulation during the first phase, more precisely at the start of this phase, it is possible to measure the current and therefore the voltage of the battery, knowing that, as mentioned above, the average current obtained for a given duty cycle depends directly on the voltage available across the battery.

Using the digital table stored in the microcomputer 10, after the start of the first interval of the first phase, the desired duty cycle is adopted.

Thus in Figure 4 the first phase is broken down into two intervals tO-t 'and f-t'1.

In the first interval the duty cycle R'1 is 100%. In the second interval the duty cycle is lower than the duty cycle R2.

Advantageously in FIG. 4, the duty cycle in the second interval of the first phase is zero for better accuracy of the measurement. In practice, the effective current during the first interval of the first phase is lower than that of FIG. 3 by being close to it. This effective current is therefore higher than that of the second phase with cyclic ratio R2.

The duration t 'of the first interval is less than the duration t1. The duration t'-t'1 of the second interval is greater than the duration t 'of the first interval. This duration is here more than double that of the first interval and allows a good measurement to be made before the start of the second phase.

For example, for a time of t1 of 4 ms, the time t 'is 3 ms and the time of the second interval t'1-t' of 7 ms.

The current at the end of phase 1 is approximately 3A lower than that in Figure 3.

In FIG. 4, the displacement of the core in phase 1 is less than half that of FIG. 1. With the ratio R ', we are in the vicinity of the separation limit of the core. Of course in FIG. 4 for simplicity, the other intervals of the second and third phase have not been shown. The device and the method proposed here therefore make it possible to optimize the progressiveness of the movement of the movable core 2b and of the pinion 1. This thus gives an increase in the life of the pinion 1 and of the drive crown as well as a reduction notable noise created by the impact of the pinion against the crown.

Even if the nucleus does not take off during the first two phases, it can be taken off. The electric motor is not running in current.

The solution is simple, reliable and economical. Of course in FIG. 3, the intensity of the effective current can be reduced in the first phase. It all depends on the displacement of the plunger core that one wishes to have. Compared to the prior art, it is possible to get as close as possible to the separation limit of the core and to better control the displacement of the latter by playing in particular over the duration of the first phase. In the prior art, it is necessary to provide a higher safety factor to be sure that the core takes off.

Thanks to the invention, the separation of the nucleus is less brutal and is better controlled, the first interval of the second phase occurring at substantially constant effective intensity. As will be understood by placing the microcontroller 10 on a card in the aforementioned manner in the vicinity of the coil 2a, it is possible to measure the temperature thereof by mounting on the card a resistor connected to the microcontroller and variable in temperature function for example with positive or negative temperature coefficient.

Claims

1. Method for supplying a coil (B) for driving a movable core (2b) of a motor vehicle electric starter contactor (2) provided with an electric motor (M), in which one varies the effective current in the coil (B) during the displacement of the core (2b) towards its contacting position, to close a movable contact (3) and feed the electric motor (M), in which one adopts during this displacement :

a first phase (t ₀ , ti) of effective current drive high enough to set the core (2b) in motion, then,

- a second phase (ti, t ₂ , t ₃ ) of lower effective current drive, characterized in that one implements, during the second phase (ti, t ₂ , t ₃ ), after a time predetermined or determined, a continuous increase in effective intensity.

2. Method according to claim 1, characterized in that the effective current during the second phase (ti, t ₂ , t ₃ ) is of the order of 0.4 to 0.6 times that applied during the first phase (t ₀ , ti).

3. Method according to claim 1 or 2, characterized in that the first phase comprises a first effective current interval sufficiently high to set the core (2b) in motion and a second effective current interval lower than that of the second phase see zero.

4. Method according to one of the preceding claims, characterized in that one implements a phase (t3, t4) at high intensity after closing the movable contact (3).

5. Device for controlling the supply of a coil (B) for driving a movable core (2b) of a motor vehicle starter switch (2), designed to vary the effective current in the coil ( B) during the displacement of the core (2b) towards its contacting position, to close a movable contact (3) of the contactor (3) and power the electric motor, in which it is intended to implement during this movement:

- a first phase (t ₀ , ti) of drive with an effective current sufficient to set the core in motion, then; - a second phase (ti, t ₂ , t ₃ ) of lower effective current drive, characterized in that it is planned during this second phase to implement after a predetermined or determined time, a continuous increase in the effective intensity.

6. Device according to claim 5, characterized in that it comprises means for measuring a supply voltage of the starter and means for adapting as a function of this voltage the effective current level during the second phase (ti, t ₂ , t ₃ ).

7. Device according to claim 5 or claim 6, characterized in that it comprises means for measuring a resistance of the coil (B) and for adapting as a function of this resistance the effective current during the second phase (ti, t ₂ , t ₃ ).

8. Device according to any one of claims 5 to 7, characterized in that it comprises means for measuring the temperature and means for adapting as a function of this temperature the effective current during the second phase (ti, t ₂ , t ₃ ).

9. Device according to one of claims 5 to 8, characterized in that it is designed to supply the coil (B) with a voltage in slots whose cyclic ratio (Ri, R ₂ ) is different in the first (t ₀ , ti) and the second phase (t !, t ₂ , t ₃ ).

10. Device according to claim 9 in combination with one of claims 6 and 8, characterized in that it comprises means (10) for deducing the duty cycle (R2) of the coil supply (B) depending of the result (s) provided by the measuring means (s).